阅读说明：本技术 包含预反应过的无机颗粒的批料组合物及由其制造生坯体的方法 (Batch composition comprising pre-reacted inorganic particles and method of making green bodies therefrom ) 是由 M·贝克豪斯-里考特 A·M·迪文斯-道彻尔 E·M·维连诺 于 2018-10-31 设计创作，主要内容包括：含有预反应过的无机球形颗粒,少量的细无机颗粒(“细料”)和极大量的液体载剂的批料组合物。所述批料组合物含有粒度分布为20μm≤D<Sub>50</Sub>≤100μm、D<Sub>90</Sub>≤100μm和D<Sub>5</Sub>≥10μm的预反应过的无机颗粒；小于20重量％的细无机颗粒(细料),其颗粒分布具有小于5μm的中位直径；以及相对于批料组合物中的所有无机颗粒,额外添加的一定重量百分比的液体载剂(LV％≥28％)。提供了具有极高τY/β比值的快速挤出的批料组合物。如其他方面一样,提供了生坯体,例如生坯蜂窝体,以及制造生坯蜂窝体的方法。(A batch composition containing pre-reacted inorganic spherical particles, a small amount of fine inorganic particles ("fines"), and a very large amount of liquid vehicle. The batch composition contains a particle size distribution D of 20 μm ≦ D 50 ≤100μm、D 90 Less than or equal to 100 mu m and D 5 The present invention provides a rapidly extruded batch composition having an extremely high ty/β ratio, comprising ≧ 10 μm pre-reacted inorganic particles, less than 20 wt% fine inorganic particles (fines) having a particle distribution with a median diameter of less than 5 μm, and an additional weight percent of a liquid vehicle (LV% ≧ 28%) relative to all inorganic particles in the batch composition.)

1. A batch composition, comprising:

pre-reacted inorganic spherical particles having the following narrow particle size distribution:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 mu m, and

D₁₀≥5μm；

an additional addition of less than 20 wt% fine inorganic particles, relative to the total weight of pre-reacted inorganic spherical particles in the batch composition, the fine inorganic particles having a median diameter of less than 5 μm; and

additional additions of ≧ 28 weight% LV%,

wherein LV% is the percentage of liquid carrier, 90% of the pre-reacted inorganic particles having a particle size distribution equal to or less than D₉₀10% of the pre-reacted inorganic particles having a diameter equal to or less than D₁₀And D, and₅₀is the median particle diameter of the particle size distribution.

2. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise 20 μm D₅₀≤45μm。

3. The batch composition of claim 2, wherein the pre-reacted inorganic spherical particles comprise 25 μm D₅₀≤45μm。

4. The batch composition of claim 1, comprising D₉₀≤75μm。

5. The batch group of claim 4A compound comprising D₉₀≤65μm。

6. The batch composition of claim 1, comprising D₁₀≥10μm。

7. The batch composition of claim 1, comprising D₁₀≥25μm。

8. The batch composition of claim 1, comprising D₉₀Less than or equal to 75 mu m and D₁₀≥5μm。

9. The batch composition of claim 8 comprising D₉₀Less than or equal to 65 mu m and D₁₀≥5μm。

10. The batch composition of claim 1, comprising D₉₀Less than or equal to 70 mu m and D₁₀≥10μm。

11. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise dB ≦ 2.00, wherein d_B＝(D₉₀-D₁₀)/D₅₀。

12. The batch composition of claim 11, wherein the pre-reacted inorganic spherical particles comprise dB ≦ 1.00.

13. The batch composition of claim 11, wherein the pre-reacted inorganic spherical particles comprise dB ≦ 0.90.

14. The batch composition of claim 11, wherein the pre-reacted inorganic spherical particles comprise dB ≦ 0.80.

15. The batch composition of claim 1, wherein the batch composition comprises less than 15 wt% fine inorganic particles having a fine particle size distribution with a median diameter of less than 5 μ ι η.

16. The batch composition of claim 15, wherein the batch composition comprises less than 10 wt% of fine inorganic particles having a median diameter of less than 5 μ ι η.

17. The batch composition of claim 1, wherein the fine inorganic particles in the batch composition comprise fine alumina and fine silica, wherein each comprises a median diameter of less than 2 μ ι η.

18. The batch composition of claim 1, wherein the fine inorganic particles in the batch composition comprise fine alumina and colloidal silica, each having a particle size distribution with a median diameter of less than 1 μ ι η.

19. The batch composition of claim 1, comprising a ratio of the total weight of fine inorganic particles in the batch composition to the total weight of pre-reacted inorganic spherical particles in the batch composition between 3:97 and 20: 80.

20. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise AR ≦ 1.2, wherein AR is an average aspect ratio measured on the pre-reacted inorganic spherical particles by dividing a first width having a largest dimension by a second width having a smallest dimension.

21. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles are formed by a spray-drying process.

22. The batch composition of claim 1, wherein the weight percentage of the additionally added liquid vehicle is greater than or equal to 30 weight percent, based on the total weight of all inorganic particles in the batch composition.

23. The batch composition of claim 1, wherein the weight percentage of the additionally added liquid vehicle is greater than or equal to 35 weight percent, based on the total weight of all inorganic particles in the batch composition.

24. The batch composition of claim 1, wherein the weight percentage of the additionally added liquid vehicle is greater than or equal to 40 weight percent, based on the total weight of all inorganic particles in the batch composition.

25. The batch composition of claim 1, wherein the weight percentage of the additionally added liquid vehicle is greater than or equal to 45 weight percent, based on the total weight of all inorganic particles in the batch composition.

26. The batch composition of claim 1, wherein the weight percentage of the additionally added liquid vehicle is greater than or equal to 28 weight percent and less than or equal to 50 weight percent based on the total weight of all inorganic particles in the batch composition.

27. The batch composition of claim 1, comprising a combination of starch and graphite as a pore former.

28. The batch composition of claim 1, comprising in combination:

an additional addition of 5 to 20 wt.% of pea starch as pore former, relative to all inorganic particles in the batch composition, and

about 1 to 10 weight percent of graphite as a pore former is additionally added relative to all inorganic particles in the batch composition.

29. The batch composition of claim 1 comprising a spherical polymeric pore former.

30. The batch composition of claim 1, comprising an additional 0.5 to 2.5 wt.% of the lubricant, relative to the weight of all inorganic particles in the batch composition.

31. The batch composition of claim 1, comprising an additional addition of 4.0 wt% to 8.0 wt% of the organic binder, relative to the weight of all inorganic particles in the batch composition.

32. The batch composition of claim 31, wherein the organic binder comprises a combination of a methylcellulose binder and a hydroxymethylcellulose binder, with a methylcellulose binder of about 3.0 to 6.0 wt.% SAT, and a hydroxymethylcellulose binder of about 1.5 to 3.0 wt.% SAT, wherein SAT is defined as an additional addition relative to the weight of all inorganic particles in the batch composition.

33. The batch composition of claim 31, wherein the organic binder comprises only hydroxymethylcellulose binder as the organic binder in an amount from about 4.0 to 8.0 weight percent SAT, wherein SAT is defined as an additional addition relative to the weight of all inorganic particles in the batch composition.

34. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase.

35. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase and a secondary mullite crystalline phase.

36. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase and a secondary feldspar crystalline phase.

37. The batch composition of claim 1, wherein the pre-reacted inorganic particles comprise a first crystalline phase comprising primarily a solid solution of aluminum titanate and magnesium dititanate, and a second crystalline phase comprising cordierite.

38. The batch composition of claim 1, wherein the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase and a secondary glass phase.

39. The batch composition of claim 1, wherein the pre-reacted inorganic particles comprise, in weight percent on an oxide basis, 4% to 10% MgO, 40% to 55% Al₂O₃25% to 44% TiO₂And 5 to 25% SiO₂。

40. The batch composition of claim 1, comprising a liquid vehicle to organic binder ratio of ≧ 6.4%.

41. A green honeycomb body comprising the batch composition of claim 1.

42. A method of manufacturing a honeycomb body, the method comprising:

mixing a batch composition comprising pre-reacted inorganic spherical particles having the following particle size distribution:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 μm, and

D₁₀≥5μm，

an additional addition of less than 20 wt% fine inorganic particles, relative to the total weight of pre-reacted inorganic spherical particles in the batch composition, the fine inorganic particles having a median diameter of less than 5 μm, and

additional additions of ≧ 28 weight% LV%,

wherein 90% of the pre-reacted inorganic spherical particles have a particle size of less than D₉₀10% of the pre-reacted inorganic spherical particles have a diameter of less than D₁₀And D, and₅₀is the median particle diameter; and

shaping a batch composition by extrusion to form a wet green honeycomb body, wherein the batch composition comprises τ Y/β ≧ 2.0, where τ Y is a measure of batch stiffness and β is a coefficient of friction of the batch composition.

43. The method of claim 42, wherein τ Y/β ≧ 3.0.

44. The method of claim 42, wherein τ Y/β ≧ 4.0.

45. The method of claim 42, wherein τ Y/β ≧ 5.0.

46. The method of claim 42, wherein τ Y/β ≧ 6.0.

47. The method of claim 42, wherein τ Y/β ≧ 7.0.

48. The method of claim 42, wherein τ Y/β ≧ 8.0.

49. The method of claim 42, wherein τ Y/β ≧ 10.0.

50. The method of claim 42, wherein the shaping comprises extrusion, and during extrusion, T^{Initiation of}Greater than or equal to 47 ℃.

51. The method of claim 50, comprising a T of greater than or equal to 50 ℃ during extrusion^{Initiation of}。

52. The method of claim 50, further comprising a T of greater than or equal to 55 ℃ during extrusion_{Initiation of}。

53. The method of claim 42, comprising:

drying the wet green honeycomb body to form a dried green honeycomb body; and

the dried green honeycomb body is fired to form a porous ceramic honeycomb body.

54. A method of manufacturing a honeycomb body, the method comprising:

mixing a batch composition comprising pre-reacted inorganic spherical particles and additionally less than 20 wt% fine inorganic particles having a median diameter of less than 5 μm, relative to the total weight of the pre-reacted inorganic spherical particles in the batch composition, and additionally more than or equal to 28 wt% LV relative to all inorganic particles in the batch composition, and

a batch composition is formed by extrusion into a wet green honeycomb body, wherein the batch composition comprises τ Y/β ≧ 2.0, τ Y is a measure of batch stiffness, and β is a coefficient of friction of the batch composition.

55. A batch composition, comprising:

pre-reacted inorganic spherical particles having the following narrow particle size distribution:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 μm, and

D₁₀≥5μm；

an additional addition of less than 20 wt% fine inorganic particles, relative to the total weight of pre-reacted inorganic spherical particles in the batch composition, the fine inorganic particles having a median diameter of less than 5 μm;

additional LV% of > 28 wt% relative to all inorganic particles in the batch composition; and

τY/β≥2.0；

wherein LV% is the percentage of liquid carrier, and 90% of the pre-reacted inorganic particles have a D or less in the particle size distribution₉₀10% of the pre-reacted inorganic particles having a diameter equal to or less than D₁₀Diameter of (D)₅₀Is the median particle diameter of the particle size distribution,. tau.Y is a measure of the rigidity of the batch, and β isCoefficient of friction of the batch composition.

Technical Field

The present disclosure relates to batch compositions comprising pre-reacted inorganic particles and methods of making green body articles therefrom.

Background

Porous ceramic honeycombs based on cordierite and aluminum titanate have been used in catalytic converters and particulate filters for diesel and gasoline engine exhaust aftertreatment.

These ceramic honeycombs can be manufactured by extruding a plasticized batch composition of inorganic and organic materials and a liquid vehicle through an extrusion die of an extruder to produce a wet green honeycomb. The wet green honeycomb body can be dried and fired to produce a porous ceramic honeycomb body.

Disclosure of Invention

Exemplary embodiments of the present disclosure relate to a batch composition. The batch composition comprises pre-reacted inorganic spherical particles having the following narrow particle size distribution:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 μm, and

D₁₀≥5μm；

an additional addition of less than 20 wt% fine inorganic particles, relative to the total weight of pre-reacted inorganic spherical particles in the batch composition, wherein the fine inorganic particles have a median diameter of less than 5 μm; and

additional LV% of > 28 wt% relative to all inorganic particles in the batch composition;

wherein LV% is the percentage of liquid carrier, 90% of the pre-reacted inorganic particles having a particle size distribution equal to or less than D₉₀10% of the pre-reacted inorganic particles having a diameter equal to or less than D₁₀And D, and₅₀is the median particle diameter of the particle size distribution.

In some embodiments, the pre-reacted inorganic spherical particles comprise 20 μm ≦ D₅₀≤45μm。

In some embodiments, the pre-reacted inorganic spherical particles comprise 25 μm ≦ D₅₀≤45μm。

In some embodiments, the batch composition comprises D₉₀≤75μm。

In some embodiments, the batch composition comprises D₉₀≤65μm。

In some embodiments, the batch composition comprises D₁₀≥10μm。

In some embodiments, the batch composition comprises D₁₀≥25μm。

In some embodiments, the batch composition comprises D₉₀Less than or equal to 75 mu m and D₁₀≥5μm。

In some embodiments, the batch composition comprises D₉₀Less than or equal to 65 mu m and D₁₀≥5μm。

In some embodiments, the batch composition comprises D₉₀Less than or equal to 70 mu m and D₁₀≥10μm。

In some embodiments, the pre-reacted inorganic spherical particles comprise dB ≦ 2.00, where d_B＝(D₉₀-D₁₀)/D₅₀。

In some embodiments, the pre-reacted inorganic spherical particles comprise dB ≦ 1.00.

In some embodiments, the pre-reacted inorganic spherical particles comprise dB 0.90.

In some embodiments, the pre-reacted inorganic spherical particles comprise dB 0.80.

In some embodiments, the batch composition comprises less than 15 wt% fine inorganic particles having a fine particle size distribution with a median diameter of less than 5 μm.

In some embodiments, the batch composition comprises less than 10 wt% fine inorganic particles having a median diameter of less than 5 μm.

In some embodiments, the fine inorganic particles in the batch composition comprise fine alumina and fine silica, wherein each comprises a median diameter of less than 2 μm.

In some embodiments, the fine inorganic particles in the batch composition comprise fine alumina and colloidal silica, each having a particle size distribution with a median diameter of less than 1 μm.

In some embodiments, the batch composition comprises a ratio of the total weight of fine inorganic particles in the batch composition to the total weight of pre-reacted inorganic spherical particles in the batch composition between 3:97 and 20: 80.

In some embodiments, the pre-reacted inorganic spherical particles comprise AR ≦ 1.2, where AR is an average aspect ratio measured on the pre-reacted inorganic spherical particles by dividing a first width having a largest dimension by a second width having a smallest dimension.

In some embodiments, the pre-reacted inorganic spherical particles are formed by a spray drying process.

In some embodiments, the weight percent of the additionally added liquid vehicle is greater than or equal to 30 weight percent, based on the total weight of all inorganic particles in the batch composition.

In some embodiments, the weight percent of the additionally added liquid vehicle is greater than or equal to 35 weight percent based on the total weight of all inorganic particles in the batch composition.

In some embodiments, the weight percent of the additionally added liquid vehicle is greater than or equal to 40 weight percent based on the total weight of all inorganic particles in the batch composition.

In some embodiments, the weight percent of the additionally added liquid vehicle is greater than or equal to 45 weight percent based on the total weight of all inorganic particles in the batch composition.

In some embodiments, the weight percent of the additionally added liquid vehicle is greater than or equal to 28 weight percent and less than or equal to 50 weight percent based on the total weight of all inorganic particles in the batch composition.

In some embodiments, the batch composition comprises a combination of starch and graphite as pore formers.

In some embodiments, the batch composition comprises a combination of: an additional addition of 5 to 20 wt% of pea starch as pore former, relative to all inorganic particles in the batch composition; and additionally 1 to 10 weight percent graphite as a pore former, relative to all inorganic particles in the batch composition.

In some embodiments, the batch composition comprises a spherical polymeric pore former.

In some embodiments, the batch composition includes an additional 0.5 to 2.5 wt% of a lubricant, relative to the total weight of all inorganic particles in the batch composition.

In some embodiments, the batch composition includes an additional addition of 4.0 wt% to 8.0 wt% of an organic binder, relative to the total weight of all inorganic particles in the batch composition.

In some embodiments, the organic binder comprises a combination of a methylcellulose binder and a hydroxymethylcellulose binder, wherein the methylcellulose binder has from about 3.0% to 6.0% by weight SAT, and the hydroxymethylcellulose binder has from about 1.5% to 3.0% by weight SAT, wherein SAT is defined as an additional addition relative to the weight of all inorganic particles in the batch composition.

In some embodiments, the organic binder comprises only hydroxymethylcellulose binder as the organic binder in an amount from about 4.0 wt.% SAT to 8.0 wt.% SAT, wherein SAT is defined as an additional addition relative to the weight of all inorganic particles in the batch composition.

In some embodiments, the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase.

In some embodiments, the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase and a secondary mullite crystalline phase.

In some embodiments, the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase and a secondary feldspar crystalline phase.

In some embodiments, the pre-reacted inorganic particles comprise a first crystalline phase comprising primarily a solid solution of aluminum titanate and magnesium dititanate, and a second crystalline phase comprising cordierite.

In some embodiments, the pre-reacted inorganic spherical particles comprise a primary aluminum titanate crystalline phase and a secondary glass phase.

In some embodiments, the pre-reacted inorganic particles comprise 4% to 10% MgO, 40% to 55% Al, based on weight% of oxides₂O₃25% to 44% TiO₂And 5 to 25% SiO₂。

In some embodiments, the batch composition comprises a liquid vehicle to organic binder ratio of ≧ 6.4%.

Exemplary embodiments of the present disclosure also relate to a green honeycomb body comprising the batch composition according to any of the embodiments described above.

Exemplary embodiments of the present disclosure also relate to methods of manufacturing honeycomb bodies. The method comprises the following steps: mixing a batch composition comprising pre-reacted inorganic spherical particles having the following particle size distribution:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 μm, and

D₁₀≥5μm，

an additional addition of less than 20 wt% fine inorganic particles, relative to the total weight of pre-reacted inorganic spherical particles in the batch composition, wherein the fine inorganic particles have a median diameter of less than 5 μm, and

additional additions of ≧ 28 weight% LV%,

wherein 90% of the pre-reacted inorganic spherical particles have a particle size of less than D₉₀10% of the pre-reacted inorganic spherical particles have a diameter of less than D₁₀And D, and₅₀is the median particle diameter.

The method further comprises the following steps: a batch composition is formed by extrusion into a wet green honeycomb body, wherein the batch composition comprises τ Y/β ≧ 2.0(Tau Y/Beta ≧ 2.0), τ Y is a measure of batch stiffness, and β is a coefficient of friction of the batch composition.

In some embodiments, τ Y/β ≧ 3.0.

In some embodiments, τ Y/β ≧ 4.0.

In some embodiments, τ Y/β ≧ 5.0.

In some embodiments, τ Y/β ≧ 6.0.

In some embodiments, τ Y/β ≧ 7.0.

In some embodiments, τ Y/β ≧ 8.0.

In some embodiments, τ Y/β ≧ 10.0.

In some embodiments, the shaping comprises extrusion, and during extrusion, T^{Initiation of}Greater than or equal to 47 ℃.

At one endIn some embodiments, the method comprises a T of greater than or equal to 50 ℃ during extrusion^{Initiation of}。

In some embodiments, the method comprises a T of greater than or equal to 55 ℃ during extrusion^{Initiation of}。

In some embodiments, the method comprises: drying the wet green honeycomb body to form a dried green honeycomb body; and firing the dried green honeycomb body to form a porous ceramic honeycomb body.

Exemplary embodiments of the present disclosure also relate to methods of manufacturing honeycomb bodies. The method comprises the following steps: mixing a batch composition comprising pre-reacted inorganic spherical particles; and additionally less than 20 wt% fine inorganic particles, relative to the total weight of the pre-reacted inorganic spherical particles in the batch composition, wherein the fine inorganic particles have a median diameter of less than 5 μm; and additional LV% of 28 wt.% or more with respect to all inorganic particles in the batch composition. The method further comprises the following steps: the batch composition is formed into a wet green honeycomb body by extrusion, wherein the batch composition comprises τ Y/β ≧ 2.0, τ Y is a measure of batch stiffness, and β is the coefficient of friction of the batch composition.

Exemplary embodiments of the present disclosure are also directed to another batch composition. The batch composition comprises pre-reacted inorganic spherical particles having the following narrow particle size distribution:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 μm, and

D₁₀≥5μm；

an additional addition of less than 20 wt% fine inorganic particles, relative to the total weight of pre-reacted inorganic spherical particles in the batch composition, the fine inorganic particles having a median diameter of less than 5 μm;

additional LV% of > 28 wt% relative to all inorganic particles in the batch composition; and

τY/β≥2.0；

wherein LV% is the percentage of liquid carrier,in the particle size distribution, 90% of the pre-reacted inorganic particles have a D or less₉₀10% of the pre-reacted inorganic particles having a diameter equal to or less than D₁₀Diameter of (D)₅₀Is the median particle diameter of the particle size distribution,. tau.Y is a measure of the rigidity of the batch, and β is the coefficient of friction of the batch composition.

Additional features of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.

Fig. 1 illustrates an isometric view of a porous ceramic honeycomb body produced from the batch composition, and particularly shown as a particulate filter, according to one or more embodiments.

Fig. 2 illustrates a graphical representation of pre-reacted inorganic spherical particles (shown as deformed for illustrative purposes) for a batch composition, according to one or more embodiments.

Fig. 3A and 3B illustrate graphs of particle size distributions of several embodiments of pre-reacted inorganic spherical particles for a batch composition, according to one or more embodiments.

Fig. 4A is a schematic diagram of an extruder for forming a wet green honeycomb body from a batch composition, according to an embodiment.

Fig. 4B illustrates an isometric view of a dried green honeycomb body produced from a batch composition, according to one or more embodiments.

Fig. 5 illustrates a flow diagram of a method for manufacturing a honeycomb body, according to one or more embodiments.

Fig. 6 illustrates a flow diagram of a method for manufacturing a honeycomb body using a batch composition, according to one or more embodiments.

FIG. 7 illustrates a graph comparing LV% (water content, in weight%) of a conventional batch composition as a function of batch stiffness τ Y and LV% of various embodiments of batch compositions including pre-reacted inorganic spherical particles as a function of batch stiffness τ Y, in accordance with one or more embodiments.

Fig. 8 illustrates a graph of LV% (water content, in weight%) versus batch friction β for a conventional batch composition and comparison of LV% versus batch friction β for various embodiments of batch compositions comprising pre-reacted inorganic spherical particles, in accordance with one or more embodiments.

Fig. 9 illustrates a cross-sectional side view of a capillary rheometer configured to test the rheological properties of a batch composition, according to an embodiment.

Fig. 10 illustrates a graph of entry pressure pe (psi) versus velocity (in inches per second) for an exemplary embodiment of a batch composition comprising pre-reacted inorganic spherical particles.

Fig. 11 illustrates plots of ptotal (psi) versus sample number for an exemplary embodiment of a batch composition comprising pre-reacted inorganic spherical particles at various velocities V and for different capillary lengths L.

Fig. 12 illustrates a plot of ptotal (psi) versus V (inches/second) for an exemplary embodiment of a batch composition comprising pre-reacted inorganic spherical particles extruded through different capillary lengths L of a capillary rheometer.

FIG. 13 illustrates a graph comparing LV% (water content, in weight%) versus τ Y/β for reactive batch compositions and LV% versus τ Y/β for various embodiments of batch compositions comprising pre-reacted inorganic spherical particles.

Fig. 14 illustrates a plot of τ Y versus β for various embodiments of reactive batch compositions and batch compositions comprising pre-reacted inorganic spherical particles.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these disclosed embodiments are provided so that this disclosure will be thorough and complete. In the drawings, the sizes and relative sizes may not be drawn to scale. Like reference numerals in the drawings denote like elements throughout the present disclosure.

Much work has been done in the honeycomb extrusion art to increase the feed rate of plasticized batch compositions through an extrusion die, as it is claimed that the feed rate is at least somewhat coupled with the cost of the final honeycomb. Thus, the increase in feed rate equates to lower production costs of the final ceramic honeycomb body. However, it is difficult to master such progress for a number of reasons.

In the manufacture of ceramic honeycomb articles, plasticized batch compositions can be considered to be non-ideal mixtures that are extruded through an extruder that includes an extrusion die having an array of fine intersecting slots. A dry batch composition of inorganic ingredients (e.g., sources of alumina, silica, titania, and/or magnesia) is combined with an organic binder, a Liquid Vehicle (LV), possibly an oil type lubricant, and optionally one or more pore formers, and plasticized by mixing and/or milling to produce a plasticized batch. The plasticized batch is then fed into an extruder, such as a twin screw extruder. As used herein, "plasticized" means the properties of a batch mixture that includes LV (e.g., deionized water) and possibly a lubricant, and that has been mixed and/or milled to have a paste consistency suitable for extrusion. As used herein, "batch composition" means a mixture of materials comprising at least inorganic raw materials, organic binders, optional pore formers, and LV. The plasticized batch composition can be configured as a slurry that is fed intermittently to the extruder or as a continuous or semi-continuous supply of mixed and/or milled plasticized batch composition and in a form and consistency that can be continuously or semi-continuously supplied to the extruder.

The plasticized batch composition can be flowed through the fine slot of the extrusion die of an extruder under pressure from one or more extruder screws (e.g., twin screw extruder) or other suitable device to form a green body, e.g., a wet green body honeycomb. The wet green honeycomb body can be dried by any suitable method, for example, by using microwave drying, Radio Frequency (RF) drying, oven drying, or a combination thereof, to form a dried green honeycomb body. After drying, the dried green body honeycomb is fired in a kiln or furnace at high temperatures to produce a porous ceramic body, such as a porous ceramic honeycomb body.

The goal is to extrude plasticized batches at as fast a feed rate as possible while also providing a wet green honeycomb of good quality that exhibits low distortion, low tear, and conforms to the desired overall geometry, as well as the desired shape of the intersecting walls and channels. Conventional batch compositions form raw inorganic powders that involve mixing and/or milling various compositions, each having a very broad particle size distribution, and having amounts of organic binder (e.g., cellulose-based binder), oil-type lubricant, LV (e.g., water), and optionally pore former. Depending on the ceramic composition sought to be formed, the source of the inorganic powders includes powdered raw materials, including sources of alumina, silica, magnesia, titania, and/or the like, wherein each of these inorganic powders has its own particular particle size distribution. In addition, particles tend to have irregular shapes, either because of processing (e.g., grinding or milling) or because of their natural shape (e.g., the flatness of clay), and also vary significantly in size. The batch composition may include a sintering aid, for example, a powdered source of strontium, calcium, or other components in conventional batches to facilitate sintering at lower temperatures. However, in these prior art conventional batch compositions, the achievable feed rate of the plasticized batch through the extrusion die is limited by the properties of the batch composition.

For example, batch stiffness and friction between irregularly shaped and broad particle size distribution batch material and the metal wall surfaces of the intersecting fine die slots of an extrusion die can limit the achievable feed rates. To some extent, batch stiffness can be adjusted by varying the relative amount of LV (e.g., water) in the plasticized batch, but shape control in these conventional batches can be degraded when the LV% is too high. Water intake (water call) as used herein is expressed as LV% SAT, where SAT means additional additions based on the total weight of all minerals in the batch composition.

For example, conventional prior art reactive batch compositions have adjusted several LV% of water to adjust extrusion while still retaining the excellent shape properties of the extruded wet green body. In conventional reactive batch compositions, the percentage of water of conventional prior art reactive batch compositions has been as high as about 25 LV% (see fig. 7 and 8). The water content in the reactive batch composition varies proportionally with the level of starch added to the batch composition. Low porosity ceramic articles can be made with no or very low starch levels and can use only about 13% water, while the same batch composition with high starch levels can use up to about 25% water to produce high porosity honeycombs. However, having too high a water percentage in such conventional batch compositions can cause certain problems in the wet green honeycomb bodies, such as clumping or collapsing (loss of outer geometry) and in some cases severe structural deformation, wall tearing or breaking, and material flow from the slots cannot weave together completely, especially for thin walls, due to lack of suitable viscosity during and after extrusion. In addition, such dried green honeycombs from these batches can excessively shrink during drying, resulting in loss of the desired overall geometry. These problems can be encountered in conventional batch compositions when additional additions are made such that the LV% in the batch composition is greater than 25% based on the total weight of the inorganic particles in the batch composition.

In addition, as the feed rate increases, the temperature of the plasticized batch composition extruded through the fine slot increases due to shear deformation. At low shear levels, the extrusion pressure remains almost constant. Above the feed rate threshold, however, the batch may no longer be able to cope with the temperature rise and thus stiffen, and may result in a significant increase in extrusion pressure. This stiffening may result in die breakage due to extremely high pressures, or simply not extrudable above a threshold feed rate, i.e., the material will not extrude.

This behavior is due to the thermal phase change of the cellulose-based organic binder included in the plasticized batch composition. At higher temperatures, the cellulose molecules lose water due to their pendant methoxy groups and hydrophobic associations occur between adjacent chains, leading to phase separation and gel formation (gelation). N.Sakar, J.Appl.Polymer Science (J.applied polymers Science) 24,1073 (1979); "Thermal gel properties of methyl-and hydroxypropyl methylcellulose". The stiffness of the plasticized batch composition increased with increasing gelation, and therefore, a dramatic increase in extrusion pressure was observed at the onset of gelation. The onset of gelation is characterized by a rather pronounced knee (change in slope) of the temperature-pressure curve and by a value T^{Initiation of}Is characterized in that. Temperature at which gelation occurs, i.e. T^{Initiation of}Is a measure of how quickly the batch will extrude.

The present inventors have noted that certain conventional batch compositions, such as conventional Aluminum Titanate (AT) batch compositions, exhibit a strong increase in pressure in their pressure-temperature curves, around 35-40 ℃. T of such conventional AT batches^{Initiation of}It is worth noting that it is advantageous to use relatively stiff batches (with a high τ Y) because this may allow better shape control of the wet green honeycomb, i.e., less wall and/or channel deformation, less tearing and less slumping (geometric deformation due to weight). the stiffness coefficient "τ Y" is a measure of the stiffness of a particular plasticized batch composition.β "is a measure of the friction of the plasticized batch composition through a slit of defined size.

Thus, in conventional batch compositions there is a natural tradeoff between the desired high batch stiffness (high τ Y) and low wall friction (low β). Thus, the ratio (τ Y/β) between the batch stiffness coefficient (τ Y) and the friction coefficient (β) can be used to characterize batch behavior during extrusion. A high ty/beta ratio is advantageous and is believed to enable higher extrusion rates. However, at stiffness favorable for extrusion, the τ Y/β ratio of conventional batches is very low, i.e., in the range between about 1.0 and 1.5.

Thus, improvements in batch compositions that allow for higher feed rates while also retaining shape control and quality of wet and dried green honeycombs would be considered a significant advance in the honeycomb extrusion art.

In view of the above limitations of conventional batches, one or more embodiments of the present disclosure provide batch compositions that enable high extrusion rates, and in some cases, extrusion rates significantly greater than optimal conventional feed rates, while also providing excellent shape control of the extrudate. For example, one or more batch compositions can achieve dramatically increased feed rates during extrusion of wet green body honeycombs. Additionally, one or more of the batch compositions can provide a relatively large process window based on the rheology of the batch composition. Such relatively large (broadened) process windows include a broadened range of extrusion pressures, extrusion temperatures, and extrusion rates.

One or more embodiments of the present disclosure include a batch composition comprising a combination of the following components: relatively coarse, pre-reacted inorganic spherical particles with a controlled and narrow particle size distribution, relatively small amounts of fine inorganic particles in the batch inorganic (hereinafter "fines"), plus an extremely high LV% in the batch composition. The fines in the batch composition are expressed as wt% SAP, where "SAP" means additional additions relative to the total amount of pre-reacted inorganic spherical particles in the batch composition. The Liquid Vehicle (LV) in the batch composition is added in weight% SAT, where SAT means additional addition relative to the total weight of the batch inorganics (weight of pre-reacted inorganic spherical particles plus "fines"). The addition of the other components of the batch composition, for example, the organic binder, lubricant, and optional pore former, are all based on weight percent SAT.

Equations 1-5 below show the respective equations for SAP and SAT:

fines in wt% SAP ═ (weight of fines/weight of PISP) x 100 equation 1

LV% SAT ═ x 100 equation 2 [ weight of LV/(weight of PISP + weight of fines) ]

Weight% SAT of organic binder ═ weight of [ OB weight/(weight of PISP + weight of fines ] x 100 equation 3

Weight% SAT of lubricant (weight of lubricant/weight of PISP + weight of fines) x 100 equation 4

Weight% SAT of pore former ═ weight of [ PF weight/(weight of PISP + weight of fines ] x 100 equation 5

Wherein:

PISP ═ pre-reacted inorganic spherical particles,

OB ═ organic binders; and is

PF is a pore-forming agent.

Applications for porous ceramic honeycombs made from the batch compositions described herein may include, for example, integration of porous ceramic honeycombs into diesel catalyst supports, gasoline catalyst supports, and/or diesel and gasoline particulate filters. In particular, the porous ceramic honeycomb may be used in automotive exhaust treatment comprising a catalytic substrate for carbon monoxide (CO) conversion, particulate filters for reducing diesel and gasoline particulate emissions, and catalyst coated particulate filters for selective catalytic reduction of nitrogen oxides (NOx). The resulting porous ceramic bodies may also be used in other filtration and/or catalytic support applications, such as porous filtration membranes, CO₂Capture devices, chemical flow reactors, chemical absorbers, molten metal filters, regenerator wicks, channel filters, candle filters, disk filters, radial flow filters, and the like. A kind ofA particularly useful example is a porous ceramic honeycomb article 100, particularly exemplified in the form of a particulate filter shown in fig. 1.

The porous ceramic honeycomb article 100 includes a porous ceramic honeycomb body 101 including a matrix of intersecting walls 102 forming channels 104, 106 extending from a first end 108 to a second end 110. In the illustrated particulate filter embodiment, some of the channels 104, 106 may be plugged by plugs (e.g., plug 112), as is known in the art. In other embodiments, no plugs are provided and the porous ceramic honeycomb body 101 may be constructed in a flow-through configuration and used, for example, as a catalyst support.

Further details, features, and exemplary embodiments of the batch compositions, their properties, green bodies (e.g., wet and dried green honeycomb bodies) and porous ceramic bodies (e.g., porous ceramic honeycomb bodies) produced from the batch compositions, and methods of making green body honeycomb and porous ceramic articles from the batch compositions, as well as others, will now be described with reference to the tables and fig. 1A-14 provided herein.

D₅₀

In the batch composition, the relatively coarse, pre-reacted inorganic spherical particles may have a particle size distribution wherein 20 μm D₅₀Less than or equal to 50 μm (including 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm and 50 μm), wherein D is₅₀Defined herein as the median particle diameter of the particle size distribution. In some embodiments, the relatively coarse, pre-reacted inorganic spherical particles have D₅₀An even narrower range of particle size distributions, as will be explained further herein. For example, in some embodiments, the median particle diameter of the pre-reacted inorganic spherical particles can be 20 μm ≦ D₅₀D is less than or equal to 45 mu m, or even less than or equal to 25 mu m₅₀Less than or equal to 45 mu m. The median particle diameter of the pre-reacted inorganic spherical particles can be adjusted by varying the solids loading and/or by varying processing parameters, such as the spray-drying pressure of a sprayer nozzle or the rotation rate of an atomizing nozzle of a spray-drying machine, the nozzle size or temperature setting of a spray-drying machine, or the organic substances added when producing green inorganic spherical particlesOr the type and amount of polymeric binder, which is calcined or fired to produce pre-reacted inorganic spherical particles.

D₉₀

In addition, the pre-reacted inorganic spherical particles may comprise a particle size distribution comprising a majority of particles below a certain coarse diameter, e.g., in some embodiments, D₉₀≤100μm，D₉₀Less than or equal to 75 μm, or even D₉₀≤60μm。D₉₀Defined herein as a certain coarse particle diameter of pre-reacted inorganic spherical particles in a particle size distribution, wherein 90% of the pre-reacted inorganic spherical particles in the distribution have a diameter equal to or smaller than the coarse diameter, i.e. the remaining particles (about 9.9999%) have a larger diameter.

D₁₀

Further, the pre-reacted inorganic spherical particles may include a particle size distribution comprising a fine fraction of particles greater than a certain size, e.g., in some embodiments, D₁₀≥5μm，D₁₀≥10μm，D₁₀≥15μm，D₁₀Not less than 20 μm, or even D₁₀≥25μm。D₁₀Defined herein as a certain fine diameter of the particles in a particle size distribution, wherein 10% of the pre-reacted inorganic spherical particles in said particle size distribution have a particle diameter equal to or smaller than the fine diameter, i.e. the remaining particles (about 89.9999%) have a larger diameter.

Additionally, in some embodiments, the pre-reacted inorganic spherical particles may comprise a relatively narrow particle size distribution, defined as having a D₉₀Less than or equal to 75 mu m and D₁₀A combination of not less than 5 μm, D₉₀Less than or equal to 65 mu m and D₁₀A combination of ≧ 5 μm, or even D₉₀Less than or equal to 70 mu m and D₁₀A combination of not less than 10 μm.

dB

In some embodiments, the relatively coarse, pre-reacted inorganic spherical particles may comprise a relatively narrow particle size distribution in terms of their width. The relatively narrow particle size distribution of the pre-reacted inorganic spherical particles can be measured in terms of the width factor dB, where the width factor dB is defined by equation 6 as:

dB＝(D₉₀-D₁₀)/D₅₀equation 6

For example, in some particularly narrow embodiments, the width factor dB of the particle size distribution according to embodiments may be defined as dB ≦ 2.00, or even dB ≦ 1.00, or even dB ≦ 0.90, or even dB ≦ 0.80.

As will be appreciated, the particle size distribution of the pre-reacted inorganic spherical particles may be engineered and/or processed to meet the pore size distribution parameters described above. The particle sizes specified herein were measured by a Microtrac (macbec) S3500 laser diffractometer.

In some embodiments, the degree of narrowness of the relatively coarse pre-reacted inorganic spherical particles may be enhanced by certain processes suitable for removing some fine portion of the pre-reacted particles therein. For example, processing such as sieving, cyclonic separation, air classification, settling or sedimentation separation, or the like may be used to remove some coarse and/or fine fractions from the particle size distribution. For example, a coarse fraction in a particle size distribution having a size greater than about 60 μm, and thus particles having a size less than 53 microns, can be removed by passing the powder through a 270 mesh screen (having a mesh opening of about 53 microns). Other screen sizes may be used to remove other portions from the large particle end of the particle size distribution. The fine fraction may also be removed by including a finer mesh screen and discarding the fraction passing through the mesh.

Fines

Additionally, the batch composition includes a small percentage of fine inorganic particles ("fines"). Specifically, the batch composition includes fine inorganic particles of less than 20% by weight SAP. The fine inorganic particles (fines) are relatively small particles in which the particle distribution of the "fines" added to the batch composition has a median particle diameter of less than 5 μm. As used herein, "SAP" means an additional addition based on the total weight of pre-reacted inorganic spherical particles included in the batch composition. In other embodiments, the batch composition includes less than 15% by weight of fine inorganic particles of SAP, wherein the distribution of fines has a median particle diameter of less than 5 μ ι η; (ii) fine inorganic particles of less than 10 wt% SAP, wherein the distribution of fines has a median diameter of less than 5 μm; or in some embodiments even less than 7.5% by weight SAP, wherein the distribution of fines has a median diameter of less than 5 μm.

In some embodiments, the "fines" in the batch composition consist essentially of a combination of fine alumina and fine silica. In further embodiments, both the fine alumina and fine silica particles added to the batch composition each comprise a distribution having a median particle diameter of less than 2 μm. In some embodiments, the batch composition comprises a combination of fine alumina and colloidal silica, wherein each comprises a distribution of particles having a median particle diameter of less than 1 μm.

In some embodiments, the fine inorganic particles ("fines") in the batch composition may comprise a combination of alumina, talc, silica, and ceria particles, wherein each has a median diameter of less than 5 μm.

In some embodiments, the batch composition may comprise fine titanium dioxide comprising a distribution of particles having a median particle diameter of less than 1 μm. In other embodiments, the fine inorganic particles in the batch composition may comprise a combination of alumina, talc, silica, and titania particles, wherein each has a median diameter of less than 5 μm. The addition of titanium dioxide particles can be used as a modifier to allow the rheological behavior of the batch composition to be adjusted by the addition of various levels of Ti.

The fine inorganic material in the batch composition acts as an inorganic binder and binds together the pre-reacted inorganic spherical particles. The fine inorganic oxide powder has a large surface area/mass and, due to its relatively large surface area, interacts strongly with the batch LV (e.g. water). Most oxides are hydrophilic and therefore they tend to "bind" large amounts of water, thereby reducing the mobility of the water and inorganic particles of the batch. Thus, the result is a thickening of the batch composition and increased friction of the batch. More internal batch friction means more friction through the batch composition passing through the extrusion die. The greater pressure to push the batch composition through the extrusion die promotes a low extrusion rate. Thus, the inventors have found that low amounts of fines, together with the use of pre-reacted particles and high water incorporation, are desirable to achieve high extrusion rates.

In other embodiments, the batch composition comprises less than 15% and greater than 3% by weight fine inorganic particles, wherein the distribution of fine inorganic particles has a median particle diameter of less than 5 μm. In other embodiments, the batch composition comprises less than 10% and greater than 3% by weight fine inorganic particles, wherein the distribution of fine inorganic particles has a median particle diameter of less than 5 μm. In some embodiments, the batch composition comprises less than 7.5 wt% and greater than 3 wt% fine inorganic particles, wherein the distribution of fine inorganic particles has a median particle diameter of less than 5 μm. In other embodiments, the batch composition comprises less than 7% and greater than 5% by weight fine inorganic particles, wherein the distribution of fine inorganic particles has a median particle diameter of less than 5 μm.

In some embodiments, the fines in the batch composition comprise about 1 to 5 wt.% of the alumina particles, 1 to 7 wt.% of the talc particles, and 0.5 to 3 wt.% of the silica particles. In some embodiments, the fine inorganic particles may comprise very fine alumina particles having a particle distribution with a median particle diameter of less than about 1 μm, or even less than 0.7 μm. In some embodiments, the fine inorganic particles may comprise fine talc particles having a particle distribution with a median particle diameter of less than about 5 μm. In some embodiments, the fine inorganic particles may comprise fine silica particles having a particle distribution with a median diameter of less than about 0.5 μm, or even less than 0.1 μm. The fine silica particles may be colloidal silica and may be provided as a suspension in water (e.g., a 40% suspension in water).

When alumina, talc and silica are used in combination as the inorganic binder, the composition is intended to form cordierite and a certain glass phase in the region between pre-reacted inorganic spherical particles after firing. To facilitate glass formation, low levels of glass-forming agents, such as cerium oxide, yttrium oxide, calcium oxide, other alkaline earth, rare earth, or alkali, can be added at levels of 1% SAP or less, including less than 0.5% SAP, less than 0.3% SAP, or even less.

When only alumina and talc are used in combination as the inorganic binder, the composition is intended to form mullite, cordierite and glass phases in the regions between pre-reacted inorganic spherical particles after firing.

When alumina, talc, silica and titania are used in combination as the inorganic binder, the composition is intended to form cordierite, aluminum titanate and a certain glass phase in the regions between pre-reacted inorganic spherical particles after firing. However, as discovered by the inventors herein, even small amounts of titanium dioxide in the batch composition can produce extremely sticky slip layers and dramatically reduce the τ Y/β ratio to near that of conventional batches. Thus, the batch composition may be substantially free of titanium dioxide due to the design for fast extrusion rates. However, as noted above, smaller amounts of titanium dioxide may be used to act as a lever to control the rheology of the batch composition.

In some embodiments, the batch composition comprises a Ratio (RFP) of a total weight of fine inorganic particles in the batch composition to a total weight of pre-reacted inorganic spherical particles in the batch composition, wherein RFT (defined as the ratio of fine to pre-reacted inorganic particles) is defined by equation 7 below:

weight equation 7 for RFT fine/PISP

In an embodiment, the RFP ratio may be between 3:97 and 20: 80.

Aspect ratio

In some embodiments, the pre-reacted inorganic spherical particles in the particle size distribution of the batch composition may have a shape that is, on average, spherical or nearly spherical and may include an Aspect Ratio (AR) and AR ≦ 1.2, as shown in FIG. 2, where AR is the average aspect ratio of all pre-reacted inorganic spherical particles in the batch composition, where AR for each pre-reacted inorganic spherical particle is measured by dividing a first width (W1) having a largest dimension on pre-reacted inorganic spherical particle 203 by a second width (W2) having a smallest dimension. To achieve this AR ≦ 1.2, the pre-reacted inorganic spherical particles 203 may be formed by a spray drying process, for example, as fully described in WO 2016138192. In some embodiments, the pre-reacted inorganic spherical particles 203 are rotary calcined at a suitable temperature to maintain the spherical shape.

Table 1 below shows examples of some pre-reacted inorganic spherical particles 203. Fig. 3A and 3B illustrate examples of representative particle size distributions of spray dried and pre-reacted inorganic spherical particles plotted.

TABLE 1 exemplary Pre-reacted particle size distribution

Fig. 3A shows examples of three representative particle size distributions of relatively coarse pre-reacted inorganic spherical particles. Additional data for relatively coarse pre-reacted inorganic spherical particles for examples of batch compositions are shown in Table 1 above, e.g., D₅₀、D₉₀、D₁₀、D₉₅、D₅And dB. Specifically, fig. 3A illustrates the median particle diameter D₅₀A relatively narrow pre-reacted particle size distribution of about 20 μm to about 30 μm, and FIG. 3B illustrates D₅₀Example of a relatively coarse distribution of pre-reacted particle size distribution of about 42 μm. Other D₅₀The values may be obtained by adjustment during the formation of green inorganic particle spheres by spray drying as described above. Additionally or optionally, sieving or other post-formation processing can be used to determine the desired median particle diameter D₅₀Adjusting to 20 μm or more and D₅₀Is more than or equal to 50 mu m. At the upper partIn the examples described, the phase composition of pre-reacted inorganic spherical particles comprises cordierite, mullite and aluminum titanate (CMAT), and comprises a solid solution of aluminum titanate and magnesium dititanate as the major phases, cordierite, a second phase of certain mullite and possibly also a glass phase. However, it should be apparent that other phase compositions of pre-reacted inorganic spherical particles may also be made.

LV％

According to another aspect, the percentage of liquid vehicle (LV%) in the batch composition is substantially higher than the amount used in conventional batches, but surprisingly retains a suitably high batch stiffness. The liquid vehicle LV provides a medium in which the organic binder is dissolved and thus provides plasticity to the batch composition and wets the inorganic particulates therein. LV may be a water-based liquid, which is typically water or a water-miscible solvent. In one embodiment, the LV is deionized water, but other solvents, such as alcohols, may also be used. In some embodiments, the liquid vehicle percent LV% of the batch composition is LV%. gtoreq.28%, or even LV%. gtoreq.30%, LV%. gtoreq.35%, or even LV%. gtoreq.40%, or even LV%. gtoreq.45%, based on the total weight of inorganic particles present in the batch composition (e.g., pre-reacted inorganic spherical particles plus "fines"), additional (SAT) by weight. In some embodiments, the% LV can comprise 28% ≦ LV% ≦ 50% with additional addition of SAT by weight. Remarkably, as discovered by the present inventors, the wet green honeycomb 446W (fig. 4A) formed from the batch composition disclosed herein [ even though it contains such an extremely high percentage of liquid vehicle (LV% ≧ 28%) ] includes extremely low wall drag, as evidenced by low β, but surprisingly also includes extremely high batch stiffness, as evidenced by relatively high τ Y, thus maintaining excellent shape control. In particular, high τ Y/β ratios are also achieved by the batch composition.

Pore-forming agent

In some embodiments, one or more pore formers may be included in the batch composition. Pore formers are particulate organic materials included in the batch composition that burn off during firing and create open interconnected pores in the fired ceramic article (e.g., in a porous ceramic honeycomb). In particular, the pore former may include a pore former material or a combination of pore former materials.

In some embodiments, the one or more pore formers may include starch, graphite, or a polymer (e.g., polymer beads). In a particularly useful embodiment, the one or more pore formers include starch, such as pea starch. In embodiments that include only starch as the organic pore former, the starch may be provided in an amount of about 5 wt% SAT to 30 wt% SAT. Other suitable starches that may be used in the batch composition as pore formers include potato starch, corn starch, sago starch, and mung bean starch. The starch may be, for example, standard starch, cross-linked starch or highly cross-linked starch.

In other embodiments, the batch composition comprises a combination of pore formers, such as a combination of starch and graphite, as the pore former. For example, in some embodiments, the batch composition includes a combination of pea starch as the pore former in an amount of 5 to 30 wt% relative to the passage of all inorganic particles (pre-reacted inorganic spherical particles and "fines") in the batch composition through the SAT and graphite as the pore former in an amount of 1 to 15 wt% relative to the passage of all inorganic particles in the batch composition through the SAT. As listed in table 3 below, the pea starch used as pore former may be a very highly cross-linked (vhxl) pea starch. For example, the median particle size of vhxl pea starch may be about d₅₀26 um. The graphite listed in table 3 may be plate-like graphite, and may be a plate having a median particle size of about 100 μm in diameter and about 10 μm in height, and includes an extremely broad particle size distribution.

In other exemplary embodiments, the batch composition comprises a spherical polymeric pore former. The spherical polymeric pore former may, for example, comprise a median particle diameter of from 15 μm to 40 μm.

Organic binder

The batch composition may include an organic binder. For example, the organic binder may be a hydrophobically modified cellulose ether binder. In some embodiments, the hydrophobically modified cellulose ether binder can be, but is not limited to, methyl cellulose, ethyl hydroxyethyl cellulose, hydroxybutyl methyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxybutyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethyl cellulose, mixtures thereof, and the like. Methylcellulose and/or methylcellulose derivatives are particularly suitable as organic binders in batch compositions using methylcellulose and hydroxypropylmethylcellulose. The source of the cellulose ether is commercially available from the Dow chemical company: (Chemical Co.)) METHOCEL^TMA cellulosic product.

Some embodiments of the batch composition may include a combination of methylcellulose and hydroxypropyl methylcellulose. Other combinations of cellulose ether binders may include cellulose ethers having different molecular weights. Alternatively, the combination of cellulose ethers may include cellulose ethers having different hydrophobic groups, cellulose ethers having different concentrations of the same hydrophobic groups, or other combinations of cellulose ethers. As a non-limiting example, the different hydrophobic groups may be hydroxyethyl or hydroxypropyl.

The organic binder in the batch composition may be provided in an amount of about 4.0 wt.% SAT to 8.0 wt.% SAT. In some embodiments, the organic binder may be a combination of a methylcellulose binder and a hydroxymethylcellulose binder with about 3.0 to 6.0 weight percent SAT in the methylcellulose binder, and about 1.5 to 3.0 weight percent SAT in the hydroxymethylcellulose binder. Some embodiments may include only hydroxymethylcellulose binder as the organic binder, for example in an amount of about 4.0 to 8.0 wt.% SAT. In some embodiments, the ratio of liquid vehicle to organic binder may be greater than or equal to 6.4%.

Lubricant/surfactant

The batch composition may also include a lubricant, for example, an oil type lubricant. Non-limiting examples of oil-based lubricants include tall oil, light mineral oil, corn oil, high molecular weight polybutenes, polyol esters, blends of light mineral oil and wax emulsions, blends of paraffin wax in corn oil, combinations of these, and the like. The amount of lubricant may be from about 0.5 wt% SAT to about 5 wt% SAT. In an exemplary embodiment, the oil lubricant may be tall oil, which is present in the batch composition from about 0.5 wt.% SAT to about 2.5 wt.% SAT.

Further, the batch composition may optionally include a surfactant. A non-limiting example of a surfactant that can be used in the batch composition is C₈To C₂₂Fatty acids and/or derivatives thereof. An additional surfactant component that may be used with these fatty acids is C₈To C₂₂Fatty acid ester, C₈To C₂₂Fatty alcohols, and combinations thereof. Exemplary surfactants are stearic acid, lauric acid, myristic acid, oleic acid, linoleic acid, palmitoleic acid and derivatives thereof, stearic acid in combination with ammonium lauryl sulfate, and combinations of all of these. The amount of surfactant in the batch composition may generally range from about 0.25 wt% SAT to about 2 wt% SAT.

Pre-reacted particulate compositions

Pre-reacted inorganic spherical particles are defined herein as spherical inorganic particles (e.g., formed by spray drying) that have been at least partially reacted (e.g., fired or calcined) to include a desired ceramic crystalline phase composition prior to being provided to the batch composition. The pre-reacted inorganic spherical particles may be formed from a mixture of component materials that react upon firing to form an oxide or non-oxide ceramic. In some embodiments, multiple crystalline phase compositions may be present in the calcined or fired particle. Pre-reacted organic spherical particles are formed to produce the desired spherical geometry with low aspect ratio AR as described herein.

Suitable processes For spray drying And calcining green inorganic particles are disclosed in WO2016/138192 entitled "Ceramic composite beads And Methods For Making The Same" And WO2014/189817 entitled "Porous Ceramic And Methods For Making The Same". Other suitable spray-drying processes for making pre-reacted organic particles may also be employed, for example, the spray-drying processes described in WO2014/189,740 and WO2014/189,741. As will be apparent, the green spherical particles may be produced by a spray drying process followed by calcination or firing to form pre-reacted inorganic spherical particles.

For example, but not by way of limitation, the pre-reacted inorganic spherical particles may include one or more phase compositions. In many embodiments, a composition of at least two phases, e.g., a major phase and a minor or minor phase, is provided. Optionally, the pre-reacted particles may comprise more than one secondary phase or secondary phase.

In some embodiments, the pre-reacted inorganic spherical particles in the batch composition can include a major phase of aluminum titanate (e.g., >50 vol%). Other minor phases may be present.

In some embodiments, the pre-reacted inorganic spherical particles in the batch composition may be formed to include any particular crystalline phase composition. In particular, in some embodiments, the batch composition may include a multi-phase crystalline phase composition. For example, some embodiments may include pre-reacted inorganic spherical particles having a primary aluminum titanate phase and a secondary glass phase.

For example, in one or more batch compositions, the pre-reacted inorganic spherical particles can comprise aluminum titanate-mullite pre-reacted inorganic spherical particles (hereinafter MAT), wherein the primary crystalline phase is aluminum titanate and the secondary crystalline phase is mullite. Other minor phases may be present.

Batch compositions comprising aluminum titanate-mullite pre-reacted inorganic spherical particles can be used to produce wet green bodies and porous ceramic bodies. For example, a green body honeycomb can be formed from a batch composition comprising pre-reacted inorganic spherical particles of aluminum titanate-mullite, and an aluminum titanate-mullite porous ceramic honeycomb can be produced by firing the green body honeycomb.

In other embodiments, the batch composition may comprise pre-reacted inorganic spherical particles of aluminum titanate-feldspar, and the batch composition may be used to green bodies and porous ceramic bodies. The pre-reacted inorganic spherical particles may comprise an aluminum titanate primary crystalline phase and a feldspar secondary crystalline phase. For example, an aluminum titanate-feldspar porous ceramic body (e.g., an aluminum titanate-feldspar porous ceramic honeycomb) can be produced. Other minor phases may be present.

In other embodiments, the batch composition may comprise pre-reacted inorganic spherical particles of cordierite, mullite, aluminum titanate (hereinafter CMAT), and the batch composition may be used to green bodies and porous ceramic bodies. CMAT is a solid solution in which the first crystalline phase is mainly aluminum titanate and magnesium dititanate, and the second crystalline phase comprises cordierite. The third crystalline phase is mullite. A glassy phase may also be present. According to some embodiments, the pre-reacted inorganic spherical particles in the batch composition comprise, in weight percent on an oxide basis, 4% to 10% MgO; 40 to 55% of Al₂O₃(ii) a 25 to 44% TiO₂And 5 to 25% SiO₂. A CMAT porous ceramic body (e.g., a CMAT porous ceramic honeycomb) can be produced from the batch composition.

In other embodiments, the batch composition comprises cordierite pre-reacted particles, and the batch composition may be used to green bodies and cordierite ceramic bodies. For example, cordierite porous ceramic bodies (e.g., green honeycomb bodies and cordierite ceramic honeycombs) can be produced. By way of non-limiting example, a composition of pre-reacted inorganic spherical particles that ultimately form cordierite upon firing is, in weight percent, about 33-41% alumina, about 46-53% silica, and about 11-17% magnesia.

The pre-reacted inorganic spherical particles described above are exemplary. The composition of pre-reacted inorganic spherical particles may optionally include other ceramic-forming compositions and combinations. For example, pre-reacted inorganic spherical particles mayOptionally having a composition comprising: feldspar, mullite, alumina, aluminosilicate, solid solutions of aluminum titanate and magnesium dititanate (pseudobrookite), spinel, rutile, cristobalite, zircon, alkali metal aluminosilicate, alkaline earth aluminosilicate, perovskite, zirconia, ceria, Silica (SiO)₂) Silicon nitride (Si)₃N₄) Silicon carbide, cerium titanate, silicon-aluminum oxynitride (SiAlON), CaO, SrO, CeO₂、Y₂O₃、La₂O₃Other rare earth oxides and zeolites.

Table 2 below shows various exemplary embodiments comprising various combinations of pre-reacted inorganic spherical particles and fines in the batch composition.

TABLE 2 exemplary batch compositions comprising pre-reacted inorganic spherical particles

Various embodiments illustrating the combination of pore former, organic binder, lubricant, and LV% in the batch composition are shown in table 3 below, wherein the batch-added weight% SAT of the pore former, organic binder, lubricant, and LV% are listed.

TABLE 3 exemplary batch composition additives

Batch rheology

In addition, as will be appreciated, these batch compositions can include extremely high τ Y/β ratios (e.g., τ Y/β ≧ 2.0, τ Y/β ≧ 3.0, τ Y/β ≧ 4.0 or greater), and can also exhibit increased T in some embodiments^{Initiation of}≥47℃、T^{Initiation of}Not less than 50 ℃ orOr even T^{Initiation of}Not less than 55 ℃. The pressure versus temperature curve is characterized by a flat portion at low temperatures before the pressure increases at higher temperatures. Initial temperature T^{Initiation of}Defined as the temperature when the pressure reaches 1.15 times the average pressure of the constant plateau pressure (as defined within a window of 15 degrees).

Thus, significantly higher extrusion feed rates can be achieved when extruding the batch composition from the extrusion die 444 (fig. 4A) as compared to conventional batch compositions. This can help reduce the cost of manufacturing a green body (e.g., a wet green honeycomb body), and thus can also reduce the cost of the final porous ceramic honeycomb body produced therefrom.

Determination of τ Y and β

A homogeneous ceramic batch composition constituting a paste was made from a mixture of batch inorganics (pre-reacted inorganic spherical particles, and "fines"), pore former particles, organic binder, LV (e.g., deionized water), and optional lubricant by high shear mixing the ingredients in a Brabender mixer (commercially available Brabender Plastograph EC 3.8kW,200NM/150 minutes, equipped with model 359 mixer). In some embodiments, the stiffness of the paste is measured with a penetrometer to ensure proper paste consistency. A commercially available penetrometer ESM-301E motorized test stand with a digital dynamometer was used.

The paste flow properties of the batch compositions were measured using a commercially available two-hole capillary rheometer (hereinafter "capillary rheometer") having an instrumented piston and multiple capillary lengths. Batch stiffness and wall drag can be measured simultaneously on a capillary rheometer. Fig. 9 shows an example of a capillary rheometer 900.

The capillary rheometer 900 used comprises a number of cylindrical barrels 902 of diameter D of 16mm and several capillaries 908 of different lengths L with small circular bores and with a capillary diameter D of 1 mm. The capillary length L is in the range of 0mm to 16mm, especially 0mm (in practice 0.25mm for practical reasons), 4mm, 10mm and 16 mm. The disc pistons 904 are mounted so that when a force F is applied to the pistons 904, for example, by applying a force F to eachA cross member 906 interconnected by a piston 904 performs translational movement in the barrel 902. After mixing as described above, the batch composition 910 that makes up the paste is placed and extruded from barrel 902 of capillary rheometer 900 into and through capillary 908 at various force F levels, thereby creating different velocities V. Representative pressure drop P across capillary rheometer 900_{General assembly}By measuring the pressure P supplied to the piston 904_{General assembly}And velocity Vp, the piston 904 contacts and causes the batch composition 910 to be extruded through the capillary 908. The total pressure P for each die (e.g., die showing long and zero lengths) is determined by pressure sensor 912_{General assembly}The pressure sensor 912 measures the pressure P exerted on the batch composition 910 contained in the barrel 902_{General assembly}。

The velocity V of the batch composition 910 in the capillary 908 is related to the piston velocity Vp by a representative area ratio according to equation 8 below, where equation 8 is:

V＝Vp(D²/d²) Equation 8

The piston velocity Vp may be measured by a suitable displacement sensor 914 coupled between (i) the piston 904 or cross member 906 and (ii) either the ground or the extruder body containing the barrel 902. The total pressure P may be provided to a suitable controller 916_{General assembly}And piston velocity Vp, the controller 916 including a suitable processor and memory configured to perform calculations sufficient to yield as output calculated values capable of producing the τ Y and β values of the batch composition.

Table 4 below shows representative raw data from an exemplary capillary velocity scan illustrating four capillaries 908 of different lengths L (L being 16mm, 10mm, 4mm and 0.25mm) and capillary diameters d of 1 mm. For each length L, the push rate of the piston 904 ("plunger") and the extrusion rate out of the capillary ("noodle") are provided, as well as the total pressure P_{General assembly}。

TABLE 4 velocities (V and Vp) and total pressures (P) during extrusion of batch compositions for various capillary lengths (0.25mm to 16mm)_{General assembly}) And (4) relationship.

When the shortest capillary 908 having a length L of 0.25mm (or about 0 mm) is used for extrusion, the batch composition 910 needs to adapt its shape from the relatively larger diameter D (16mm) of the barrel 902 to the relatively smaller diameter D (1mm) of the capillary 908. A pressure drop P across the capillary 908 ("about zero capillary")_{General assembly}Corresponding to the batch stiffness through the pressure required for the batch composition to shrink from a 16mm barrel geometry to a 1mm capillary 908. The use of "about zero capillary" can be indicated and can be used to determine the entrance loss component because its short length (about L-0) minimizes the wall drag component and thus can be effectively ignored. The use of longer capillaries (e.g., 16mm long capillaries) results in a wall drag component due to friction/drag along the length L of the wall of the capillary 908 and a stiffening of the batch composition due to its shape change, i.e., an in-loss component. Thus, the measured pressure drop P as a function of the velocity V_{General assembly}An entrance loss component Pe and a wall drag component Pw may be included, which are separable as will be apparent.

At 10 different speeds V [ effective velocity (V) from 0 mm/sec to 4 inches/sec (101.6 mm/sec) ]]The batch compositions were tested for different lengths of capillary tubing (0mm to 16mm) having a capillary length L using a capillary velocity scan test at a constant temperature of about 25 ℃. The extrusion velocity V (noodles) through the capillary 908 is increased stepwise to successively higher velocities V, and when a steady-state velocity V is reached, a representative total pressure drop (P) per step is recorded via sensor 912_{General assembly}). This original P will be for each length L of the capillary 908_{General assembly}And velocity V data are provided to controller 916, stored in memory and further calculated as described herein to calculate τ Y and β for each measured batch composition table 5 below shows exemplary values for one batch composition.

TABLE 5L/d, noodle speeds V, Tw, Pe-average and Pe intercept

As shown in fig. 10, the graph of entry pressure pe (psi) versus velocity V (in/sec) illustrates the non-linearity of the entry pressure loss as a function of velocity V provided by a zero length (0.25 in) capillary 908.

Representative examples of raw data output from capillary velocity scan testing using four different sized capillaries (0.25mm to 16mm) and 10 speeds are shown in fig. 11, which illustrates the test values for batch compositions comprising pre-reacted inorganic spherical particles (where higher L values indicate higher pressures) in multiple stages and multiple curves, each corresponding to one capillary length. In the example shown, the scan test is repeated twice. The raw data may be converted into a pressure versus velocity map using any suitable software program. Figure 12 shows an exemplary pressure versus velocity plot for spray dried pre-reacted CMAT batch compositions.

As mentioned above, the total measured pressure drop P_{General assembly}Equal to the entry pressure Pe plus the wall drag contribution Pw, and can be represented by the relationship:

P_{general assembly}＝Pe+Pw

A number of models have been developed that relate the geometric shrinkage of batch composition 910 in capillary rheometer 900 from D to D and the pressure drop through capillary 908 to the batch rheology. The capillary characteristics include capillary diameter d, capillary length L, and some constants that contain aspects related to capillary material and capillary surface roughness, but these constants do not change for a given capillary 908 of a given length L and diameter d. The test methods described herein are used to determine batch rheological characteristics, including τ Y (yield stress) and β (wall drag coefficient), which are unique parameters that define the rheological properties of the various batch compositions described herein.

The bo-bridqiwatt (Benbow-Bridgwater) model is used to describe the wall drag force Pw as a function of capillary length L, capillary diameter d, velocity V, wall drag coefficient β (beta) and wall velocity index m [ see literature: benbow, J.Bridgwater, Paste flow and extrusion, Oxley, Oxford university Press, 1993 and J.J.Benbow, E.W.Oxley, J.Bridgwater "The extrusion mechanics of The Paste-The effect of The Paste formulation on The extrusion parameters"; science (Chemical engineering science) 53,2151 (1987). The model characterizes the wall drag force Pw as the following equation 9:

Pw＝{4L/d}[βV^m]equation 9

Wherein:

l is the capillary length

d is the capillary diameter

Beta (beta) is the wall drag coefficient

m is wall velocity index

V is paste velocity at the wall

But the shear stress Tw at the wall is as shown in equation 10 below:

Tw＝βV^mequation 10

Thus, the wall drag pressure component can be expressed as the following equation 11:

pw ═ 4L/d) Tw equation 11

The natural logarithm of shear stress (ln (tw)) is plotted against the natural logarithm of velocity (ln (v)). From this plotted data, the term β can be found as the y-intercept of the ln (tw) and ln (v) plots, and m is the slope of this line. The slope m is determined within the length data of 0 inch/sec to 4 inch/sec. Outliers were ignored and the test was performed multiple times and the results were averaged for each batch composition.

The inlet pressure Pe can be approximated by equation 12 below:

Pe＝2{τY+kVⁿ{ Ln (D/D) } equation 12

Suppose P_{General assembly}The model defines a total pressure P as shown in equation 13 below:

P_{general assembly}＝2{τY+kVⁿ}{Ln(D/d)}+{4L/d}[βV^m]Equation 13

Wherein:

τ Y is the yield stress of the batch composition

k is the consistency index

n is the body velocity index

D is the diameter of the extruder barrel

d is the capillary diameter

L is the capillary length

Beta (beta) is the wall drag coefficient

m is wall velocity index

V is paste velocity at the wall

The values of τ Y, k and n can be found from the measured data by three-parameter curve fitting using a solver, such as the solver provided in MS Excel or any other iterative solver, to minimize the difference between the measured and calculated parameters. The values of τ Y and β (beta) are parameters used herein to characterize the extrusion rheology of the batch compositions described herein, and are calculated as described above. Based on this measured raw data, controller 916 calculates τ Y and β.

More specifically, fig. 7 illustrates a graph showing a comparison of the LV% (liquid vehicle content, wt% SAT) of a conventional batch composition compared to the LV% used in various embodiments of batch compositions comprising pre-reacted inorganic spherical particles. As should be noted, in many cases comparable batch stiffness τ Y can be achieved even with significantly higher LV%. For example, comparable τ Y can be achieved up to two times LV% or more, while also achieving excellent batch stiffness.

Fig. 8 illustrates a graph comparing LV% (water content, in weight percent SAT) of a conventional batch composition versus batch friction β (beta) and LV% of various embodiments of batch compositions comprising pre-reacted inorganic spherical particles versus batch friction β, according to embodiments. As evidenced by the graph of FIG. 8, significantly lower β is achieved when the batch composition used comprises pre-reacted inorganic spherical particles, a small amount of "fines" and LV%. gtoreq.28%. As can be seen in FIG. 8 and Table 6 below, relatively low β (coefficient of friction) values may be achieved with the batch compositions, e.g., β ≦ 10, β ≦ 7, β ≦ 6, β ≦ 5, β ≦ 4, and even β ≦ 3, according to embodiments of the batch compositions described herein.

Fig. 13 illustrates LV% (water content, in weight% SAT) versus τ Y divided by β (beta) for various embodiments of conventional batch compositions and batch compositions comprising pre-reacted inorganic spherical particles, according to embodiments. As demonstrated in the graph of fig. 13 and table 6 below, the batch compositions described herein have significantly higher τ Y/β ratios than conventional batch compositions.

For example, some embodiments shown in FIG. 13 and Table 6 below may include ratios of τ Y/β ≧ 2.0, τ Y/β ≧ 3.0, τ Y/β ≧ 4.0, τ Y/β ≧ 5.0, τ Y/β ≧ 6.0, τ Y/β ≧ 7.0, τ Y/β ≧ 8.0, or even τ Y/β ≧ 10.0. In some embodiments, the ratio of τ Y/β may be 2.0 ≧ τ Y/β ≧ 10.0. As will be appreciated, the value of τ Y/β is related to the extrusion rate, which is significantly higher than conventional batches, which may have τ Y/β values between about 0.85 and 1.50. Thus, batch compositions exhibiting τ Y/β values may achieve relatively high extrusion rates.

Table 6 below illustrates LV% (SAT), liquid to organic binder ratios for various embodiments of the batch compositions, and also illustrates rheological measurements of τ Y, β, and τ Y/β.

TABLE 6 rheology measurements of exemplary CMAT batch compositions

Machining

In another aspect, as shown broadly in fig. 5 and in more detail in fig. 6, the present disclosure provides methods 500, 600 of manufacturing a honeycomb body. The methods 500, 600 may include increased extrusion rates when formed through the extrusion die 444 (fig. 4A) as compared to batch compositions having conventional reactive batch components. The manufacturing method 500, 600 includes: a batch composition is provided in 502, 602 that includes pre-reacted inorganic spherical particles, a small amount of "fines," and a high LV% (e.g., ≧ 28%). In fig. 6, the batch composition comprises in detail at 602: pre-reacted inorganic spherical particles having a narrow particle size distribution, wherein the narrow particle size distribution is defined by:

20μm≤D₅₀≤50μm，

D₉₀less than or equal to 100 μm, and

D₁₀≥5μm，

fine inorganic particles ("fines") in an amount of less than 20% by weight SAP, wherein the "fines" have a median diameter of less than 5 μm and an additional LV% ≧ 28% by weight, relative to all inorganic particles in the batch composition. The batch composition may also include added organic binders, lubricants, surfactants, and/or optional pore formers, as described herein.

The method 500, 600 further comprises: the batch compositions are mixed in 504, 604. The mixing in 604 may include: LV and a lubricant are added to the dry ingredients (pre-reacted inorganic spherical particles, fine inorganic particles, and organic binder) to at least partially plasticize the batch composition, i.e., to provide a paste consistency.

The method 500 further includes: the batch composition is formed into a wet green honeycomb body at 506. At 606, the shaping can be by extrusion, wherein the properties of the batch composition include τ Y/β ≧ 2.0, thereby providing a significantly increased extrusion rate through the extrusion die 444. Shape control is preserved.

According to method 500, LV (e.g., deionized water) may be added at a LV% of LV ≧ 28% SAT, relative to the total amount of pre-reacted inorganic particles and organic particles. In other embodiments, additional addition of SAT by weight based on the total weight of inorganic particles (pre-reacted inorganic spherical particles plus "fines") present in the batch composition may be added with LV ≧ 30%, LV% ≧ 35%, LV% ≧ 40%, or even LV% ≧ 45%. In some embodiments, LV% is 28% ≦ LV% ≦ 50%.

The extrusion method 500 may include: the organic binder is added, for example, in an amount between about 4.0 wt% SAT and 8.0 wt% SAT. In some embodiments, the organic binder may be a combination of a methylcellulose binder and a hydroxymethylcellulose binder with about 3.0 to 6.0 weight percent SAT in the methylcellulose binder, and about 1.5 to 3.0 weight percent SAT in the hydroxymethylcellulose binder. Some embodiments may include only hydroxymethylcellulose binder, for example in an amount between about 4.0 and 8.0 weight percent SAT.

At 504, 604, the inorganic particles, organic binder, optional pore former, LV, and lubricant may be mixed by any suitable mixing device or combination of mixing devices, e.g., a Muller mill, a screw mixer, a double arm mixer, or a plow blade paddle mixer, etc., to begin plasticization. LV may be added to hydrate the organic binder and inorganic particles, and a lubricant and/or surfactant may be added to the batch composition to wet through the organic binder and inorganic particles and form a partially plasticized batch composition. At 506, the batch composition can be suitably formed into a wet green honeycomb body 446W from the plasticized batch composition 404 by any suitable forming process. For example, the wet green honeycomb body 446W may be manufactured by forming techniques such as uniaxial or isostatic pressing, injection molding, extrusion, and the like.

In some embodiments, the batch composition may be formed into a partially plasticized mass 402, which may be provided to an extruder 400, as shown in fig. 4A. In other embodiments, the batch composition may be added to the extruder 400 as a continuous or semi-continuous stream of a relatively small amount of material, such as a small slurry or even a pellet or stream of a partially plasticized batch composition. As shown in fig. 4A and as described with reference to fig. 5, the partially plasticized batch composition 404 can be formed into a wet green honeycomb body 446W at 506, 606.

Referring again to fig. 4A and 5, one or more batch compositions 404 in the form of a pug 402 can be provided to the extruder 400 and extruded from the extruder 400 to form and shape the batch composition into a wet green honeycomb body 446W. Extrusion can be performed using any suitable type of extruder 400 that provides a suitable amount of shear to the batch composition 404. For example, a hydraulic ram extruder, a two-stage degassing single auger, a single screw extruder, a twin screw extruder, or the like may be used. Fig. 4A illustrates one example of forming and shaping a wet green honeycomb body 446W using an extruder 400 comprising one or more screws.

In more detail, the extruder 400 may include a screw section that includes one or more extrusion screws 418 that are rotatable within an extruder barrel 420. The one or more extrusion screws 418 may be driven by a motor 422 at the inlet end of the extruder barrel 420. In a twin screw embodiment, the extruder 400 may include two extrusion screws 418. The extruder barrel 420 can be equipped with an inlet port 424 for introducing the batch composition 404 for further plasticization in the extruder 400. A mixing plate 426 may be positioned downstream of the screw section and may be contained within a barrel 428, the barrel 428 being mounted on the outlet end of the extruder barrel 420. After the screw section, the mixing plate 426 further mixes, homogenizes, and plasticizes the batch composition 404.

Also disposed within barrel 428 are filter screen 410 and filter support 430, each of which is located upstream of mixing plate 426 with respect to the direction of flow (shown as directional arrows) of batch composition 404 pumped by extrusion screw 418. Filter screen 410 is mounted against filter support 430 to form a filter assembly configured to remove large particles, agglomerates, or debris that may clog extrusion die 444. Preferably, the filter support 430 is formed to have a plurality of openings and/or slits. The extruder 400 also includes an extrusion die 444 mounted downstream of the filter assembly and mixing plate 426 at the outlet end of the barrel 428. The die includes a plurality of upstream feedholes and a plurality of downstream intersecting slots. The filter assembly is used to remove large accumulations and debris that may clog the slots of the extrusion die 444. The plasticized batch composition 404 flows through the plurality of intersecting slots of the extrusion die 444, which forms a matrix of intersecting walls 102 and channels 104 in the wet green honeycomb 446W corresponding to the honeycomb 446D.

Thus, during operation of the extruder 400, the plasticized batch composition 404 is pumped from the extruder barrel 420 by the one or more extrusion screws 418, then through the filter screen 410, the filter support 430, the mixing plate 426 and finally exits the extrusion die 444 of the extruder 400 as a wet green honeycomb body 446W. The wet green honeycomb body 446W may be cut by a cutting apparatus 448 that includes a cutting device, such as a wire. Once cut, the wet green honeycomb body 446W may be received on a tray 450.

The wet green honeycomb body 446W may then be dry transported by the tray 450 and conveyor (not shown) to a dryer (not shown) and dried by any suitable drying process at 508, e.g., oven drying, microwave drying, RF drying, combinations thereof, or the like, to form a dried green honeycomb body 446D (fig. 4B). The dried green honeycomb body 446D includes a plurality of intersecting walls 102 extending from one end of the green honeycomb body 446D to the other. The intersecting walls 102 form a channel 104 that also extends from one end to the other.

Firing

Next at 510, the dried green honeycomb body 446D may be fired according to known firing techniques to form the porous ceramic honeycomb body 101, as shown in FIG. 1. For example, the dried green honeycomb body 446D can be fired in a gas or electric kiln under conditions effective to convert the dried green honeycomb body 446D into a ceramic article (e.g., porous ceramic honeycomb body 101). The firing conditions in terms of temperature and time depend on the particular batch composition and dimensions and geometry of the dried green honeycomb body 446D.

For example, firing conditions effective to convert the dried green honeycomb body 446D into the porous ceramic honeycomb body 101 can include: the dried green honeycomb body 446D is heated in a furnace and in an air atmosphere to a maximum soaking temperature at a heating rate of 120 ℃/h, for example, in the range of 1000 ℃ to 1600 ℃, depending on the batch composition. The maximum soaking temperature may be maintained for a holding time of between about 1 and 30 hours sufficient to convert the dried green honeycomb body 446D into a ceramic article. The cooling can then be performed at a rate that is sufficiently slow (e.g., a cooling rate of about 10 to 160 ℃/hour) that the porous ceramic honeycomb body 101 does not thermally shock and crack. The firing time also depends on factors such as the type and amount of particulate material and pore former, and the nature of the firing apparatus, but the total firing time may be, for example, from about 20 hours to about 80 hours.

For batch compositions used primarily to form aluminum titanate compositions, the maximum firing temperature is from about 1300 ℃ to about 1450 ℃, and the hold time at this temperature is from about 1 hour to about 6 hours.

For batch compositions used primarily to form aluminum titanate-mullite phase compositions, the maximum firing temperature is from about 1340 ℃ to about 1500 ℃, and the hold time at that temperature is from about 1 hour to about 6 hours.

For batch compositions used primarily to form cordierite-mullite, aluminum titanate (CMAT) phase compositions, the maximum firing temperature is from about 1300 ℃ to about 1380 ℃, and the hold time at this temperature is from about 1 hour to about 6 hours.

For batch compositions used primarily to form mullite, the maximum firing temperature is from about 1400 ℃ to about 1600 ℃, and the hold time at that temperature is from about 1 hour to about 6 hours.

For cordierite-mullite-forming mixtures that result in the aforementioned cordierite-mullite compositions, the maximum firing temperature is from about 1375 ℃ to about 1425 ℃ and the hold time at that temperature is from about 1 hour to about 6 hours.

For example, in compositions used primarily for cordierite formation, the maximum firing temperature is from about 1300 ℃ to about 1450 ℃, and the hold time at this temperature is from about 1 hour to about 6 hours.

Porous ceramic articles produced from batch compositions

Porous ceramic articles (e.g., porous ceramic honeycombs) made from batch compositions comprising pre-reacted inorganic spherical particles, relatively minor amounts of "fines" (. ltoreq.20 wt% SAP, particle distribution with median particle diameter less than 5 μm), and LV%. gtoreq.28% can exhibit suitable open interconnected pores and microstructures after firing to serve as catalyst supports and/or particulate filters.

For example, in some embodiments, a relatively large Median Pore Size (MPS), high porosity (% P), good strength, and low Coefficient of Thermal Expansion (CTE) may be provided, which when implemented as a particulate filter, can provide both low pressure drop and good impact resistance.

According to an exemplary embodiment of the present disclosure, a porous ceramic honeycomb body 101 (fig. 1) having a reverse pore structure achieves relatively high permeability. For example, in some embodiments, the porosity of the porous ceramic honeycomb body may be greater than 50%, greater than 55%, or even greater than 60%. In some embodiments, the median pore diameter (d50) of the porous ceramic honeycomb body 101 can be greater than 10 μm, or even greater than 15 μm, and between 10 μm and 30 μm.

The porous ceramic honeycomb body 101 may have a coefficient of thermal expansion of less than 20 × 10 at Room Temperature (RT) to 800 ℃^-7K^-1E.g. less than 15 × 10^-7K^-1Or even less than 10 × 10^-7K^-1. Further, the flexural modulus of rupture (MOR) strength of the (300/14) honeycomb of the porous ceramic honeycomb body 101 can be, for example, greater than 170psi, or even greater than 200 psi.

FIG. 1 illustrates an isometric view of a porous ceramic honeycomb article 100 according to an exemplary embodiment of the present disclosure. The porous ceramic honeycomb article 100 is embodied as a particulate filter and includes a first end 108, which may be an inlet end, and a second end 110 opposite the first end 108, and a plurality of inlet channels 104 extending from the first end 108 to the second end 110. Likewise, the plurality of outlet channels 106 may also extend from the first end 108 to the second end 110. The plurality of intersecting walls 102 form inlet channels 104 and outlet channels 106 and form a honeycomb matrix. At the first end 108 of the outlet channel 106, the first end 108 may include a plug 112. Likewise, the second end 110 (outlet end) may also include a plug 112 (not shown in FIG. 1) in the end of the inlet passage 104. Thus, in some embodiments, a checkerboard pattern of plugs 112 may be formed on both the first end 108 and the second end 110. Other plugging configurations may be employed, including partially plugged configurations in which some channels are plugged and some channels are unplugged (i.e., flow-through channels). Porosity, median pore diameter and pore size distribution were determined by tomographic techniques.

The cell density of the porous ceramic honeycomb body 101 may be about 70 to 1200 cells per square inch (cpsi) (about 10 to 190 cells per square centimeter). The cell wall thickness can range from about 0.025mm to about 1.5mm (about 0.001 to 0.060 inches). For example, the geometry of the porous ceramic honeycomb body 101 may be 400cpsi with a wall thickness of about 8 mils (400/8) or a wall thickness of about 6 mils (400/6). Other geometries may include, for example, 100/17, 200/12, 200/19, 270/19, 350/3, 400/3, 400/4, 500/2, 600/2, 600/3, 600/4, 750/2, 900/2, 900/3, 1200/2, and even 750/1 and 900/1. Other suitable combinations may also be produced using the batch composition.

As used herein, a porous ceramic honeycomb is intended to encompass any honeycomb structure, i.e., cell shape, and is not strictly limited to square cell shapes. For example, the cells of the porous ceramic honeycomb body 101 may be square, rectangular, hexagonal, octagonal, triangular, or any other suitable cell shape. Also, although the cross section of the porous ceramic honeycomb body 101 is shown as a circle, the cross sectional shape is not limited thereto. For example, the cross-sectional shape may be oval, racetrack, square, rectangular, or other desired geometry.

An outer peripheral surface is provided at the outer periphery of the matrix of the intersecting walls 102. The peripheral surface may include a skin layer 105 therein, and in some embodiments, may be formed as a co-extruded skin layer that is co-formed with the intersecting walls 102. In other embodiments, the subsequently applied outer skin may form an outer peripheral surface extending axially from the first end face to the second end face of the porous ceramic honeycomb body 101. As used herein, the porous ceramic honeycomb body 101 includes ceramic honeycomb monoliths as well as segmented ceramic honeycomb bodies, i.e., ceramic honeycomb segments that are adhered together.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.