阅读说明：本技术 一种高透明度醋酸纤维素材料及其制备方法 (High-transparency cellulose acetate material and preparation method thereof ) 是由 台启龙 赵铭 何明山 陈丽娟 于 2021-10-14 设计创作，主要内容包括：本发明公开了一种高透明度醋酸纤维素材料及其制备方法,该高透明度醋酸纤维素材料,以重量百分比计,原料组成包括：醋酸纤维素100份；增塑剂17～25份；交联剂0.1～2份；其它助剂0.1～2份；所述交联剂选自异氰酸酯类、二酸酐类或过氧化物类；所述交联剂的熔点不高于120℃。制备工艺包括将所有原料共混均匀后,先经加热处理进行熔融预交联改性,再经挤出、造粒、干燥后得到所述的高透明度醋酸纤维素材料。采用上述原料与工艺制备得到的醋酸纤维素材料不仅显著减少了增塑剂的用量,降低其析出的风险；而且制备得到的醋酸纤维素材料具有高透光率与低雾度,同时工艺流程简便,耗时短,生产效率高,适合大规模工业化生产。(The invention discloses a high-transparency cellulose acetate material and a preparation method thereof, wherein the high-transparency cellulose acetate material comprises the following raw materials in percentage by weight: 100 parts of cellulose acetate; 17-25 parts of a plasticizer; 0.1-2 parts of a crosslinking agent; 0.1-2 parts of other auxiliary agents; the cross-linking agent is selected from isocyanates, anhydrides or peroxides; the cross-linking agent has a melting point of not higher than 120 ℃. The preparation process comprises the steps of uniformly blending all the raw materials, heating to perform melting pre-crosslinking modification, extruding, granulating and drying to obtain the high-transparency cellulose acetate material. The cellulose acetate material prepared by adopting the raw materials and the process not only obviously reduces the dosage of the plasticizer, but also reduces the risk of precipitation; the prepared cellulose acetate material has high light transmittance and low haze, and is simple and convenient in process flow, short in time consumption, high in production efficiency and suitable for large-scale industrial production.)

1. The high-transparency cellulose acetate material is characterized by comprising the following raw materials in parts by weight:

the cross-linking agent is selected from one or more of isocyanates, diacid anhydrides and peroxides;

the cross-linking agent has a melting point of not higher than 120 ℃.

2. The high-transparency cellulose acetate material according to claim 1, wherein the cellulose acetate is cellulose diacetate derived from cellulose acetate from wood pulp or bamboo pulp.

3. The high-transparency cellulose acetate material according to claim 1, wherein the plasticizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, polyethylene glycol, phthalic acid esters, triacetin and citric acid esters.

4. The high transparency cellulose acetate material according to claim 1, characterized in that:

the isocyanate is selected from one or two of triallyl isocyanurate and triglycidyl isocyanurate;

the diacid anhydride is selected from one or more of succinic anhydride, glutaric anhydride, adipic anhydride and maleic anhydride;

the peroxide is one or two selected from dicumyl peroxide and 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane.

5. The high-transparency cellulose acetate material as claimed in claim 1, wherein the other auxiliary agents comprise at least one of an antioxidant, a lubricant and a nucleating agent.

6. The high-transparency cellulose acetate material as claimed in any one of claims 1 to 5, wherein the raw material composition comprises, in parts by weight:

the cross-linking agent is selected from isocyanates and/or anhydrides.

7. The high clarity cellulose acetate material according to claim 6 wherein the crosslinking agent is selected from the group consisting of anhydrides.

8. The preparation method of the high-transparency cellulose acetate material according to any one of claims 1 to 7, comprising:

after all the raw materials are uniformly blended, the raw materials are heated for melting and pre-crosslinking modification, and then the high-transparency cellulose acetate material is obtained after extrusion, granulation and drying.

9. The method for preparing the high-transparency cellulose acetate material according to claim 8, wherein the heating treatment is carried out at a temperature of 80-120 ℃ for 1-5 hours.

10. The method for preparing the high-transparency cellulose acetate material according to claim 8, wherein the extrusion temperature is 160 to 180 ℃ and the screw rotation speed is 50 to 300 rpm.

Technical Field

The invention belongs to the field of cellulose acetate materials, and particularly relates to a high-transparency cellulose acetate material and a preparation method thereof.

Background

Cellulose Acetate (CA) is a cellulose derivative obtained by acetylation of cellulose, and has been commercialized for the first time. The performance of the cellulose acetate depends on the acetylation degree of hydroxyl groups in the production process, and the cellulose acetate has the characteristics of good toughness, good luster, high mechanical strength, high transparency, stability to light, difficult combustion and the like. At present, cellulose acetate is widely used in the fields of cigarette filters, textile fibers, medical materials, separation membranes and the like.

The prior methods for preparing or improving the transparency of the cellulose acetate transparent product mainly comprise the following steps: 1. the solvent method is that after the cellulose acetate is dissolved by using low boiling point organic solvents such as acetone, methyl acetate, dioxane and the like, the cellulose acetate is molded by casting and other processes; and 2, adding a small-molecular plasticizer which can weaken the secondary bond effect among the cellulose acetate molecules, improve the motion capability of molecular chains, reduce thermal decomposition in the melting processing process and improve the transparency of a cellulose acetate product. However, the products obtained by the solvent method are mainly limited to transparent films, the cost is high, and the used organic solvents have potential hazards (such as toxicity or flammability and the like), so that potential safety hazards are brought to manufacturers and users. The method for adding the small-molecule plasticizer is simple to operate, is suitable for various processing modes, and is widely applied.

However, this process often requires the addition of relatively large amounts of plasticizer. Moreover, in order to ensure a good plasticizing effect of the plasticizer, a long aging time is required.

For example, chinese patent publication No. CN 102050964 a discloses a cellulose acetate transparent plastic and a method for producing the same, wherein the cellulose acetate transparent plastic comprises 100 parts of cellulose acetate, 25-54 parts of a plasticizer, and 0.4-0.8 part of an antioxidant. The usage amount of the plasticizer in the technical scheme reaches 25% -54% of the usage amount of the cellulose acetate. A large amount of plasticizer has a risk of precipitation, which not only affects the durability of the product, but also brings hidden troubles to users. In addition, in the technical scheme, after the raw materials are blended, the raw materials are required to be placed at 25 ℃ for 24 hours for curing. This also greatly reduces the production efficiency and is not conducive to the realization of industrial production.

Disclosure of Invention

The invention discloses a high-transparency cellulose acetate material, which utilizes the synergistic effect of a plasticizer and a cross-linking agent, so that the dosage of the plasticizer is obviously reduced, and the risk of precipitation is reduced; the prepared cellulose acetate material has high light transmittance and low haze, and is simple and convenient in process flow, short in time consumption, high in production efficiency and suitable for large-scale industrial production.

The specific technical scheme is as follows:

a high-transparency cellulose acetate material comprises the following raw materials in percentage by weight:

the cross-linking agent is selected from isocyanates, anhydrides or peroxides;

the cross-linking agent has a melting point of not higher than 120 ℃.

The invention discloses a high-transparency cellulose acetate material, wherein a specific cross-linking agent is additionally added into a cellulose acetate substrate, in the process of melt cross-linking pretreatment, the cross-linking agent is melted at a temperature higher than the melting point of the cross-linking agent and permeates into cellulose acetate molecules, the movement capability of a cellulose acetate molecular chain is improved under the synergistic action of a plasticizer, and the invention has the advantages of further improving the transparency of a cellulose acetate product and obviously reducing the dosage of the plasticizer.

Preferably, the cellulose acetate is cellulose diacetate, and the source thereof is selected from cellulose acetate from wood pulp and cellulose acetate from bamboo pulp, in view of raw material price and availability.

Preferably, the plasticizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, polyethylene glycol, phthalate, glyceryl triacetate and citrate.

Preferably:

the isocyanate is selected from one or two of triallyl isocyanurate and triglycidyl isocyanurate;

the diacid anhydride is selected from one or more of succinic anhydride, glutaric anhydride, adipic anhydride and maleic anhydride;

the peroxide is one or two selected from dicumyl peroxide and 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane.

More preferably, the crosslinking agent is selected from isocyanates and/or anhydrides, and even more preferably from anhydrides.

Preferably, the other auxiliary agents comprise at least one of an antioxidant, a lubricant and a nucleating agent. The antioxidant is added to inhibit the degradation of cellulose acetate during processing, the lubricant is added to improve the fluidity of the melt and increase the surface gloss of the product, and the nucleating agent is added to reduce the size of crystal nuclei during crystallization and increase the transparency of the product.

The kind of the antioxidant is not particularly selected, and may be selected from conventional ones in the art, such as pentaerythritol tetrakis (β - (3, 5-di-t-butyl-4-hydroxyphenyl) propionate), n-octadecyl β - (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, tris (2, 4-di-t-butylphenyl) phosphite, and the like.

The type of lubricant is not particularly selected and may be selected from the conventional types in the art, such as from erucamide, oleamide, pentaerythritol stearate, and the like.

The type of nucleating agent is not particularly selected and may be selected from conventional types in the art, such as talc, calcium carbonate, ethylene bis stearamide, dibenzylidene sorbitol, and the like.

In addition to the above-described preferred types of raw materials, it is further preferred that:

the high-transparency cellulose acetate material comprises the following raw materials:

the invention also discloses a preparation method of the high-transparency cellulose acetate material, which comprises the following steps:

after all the raw materials are uniformly blended, the raw materials are heated for melting and pre-crosslinking modification, and then the high-transparency cellulose acetate material is obtained after extrusion, granulation and drying.

The blending may be accomplished in a high mixing machine.

The temperature of the heating treatment is 80-120 ℃, and the time is 1-5 h. And (3) extruding: the extrusion temperature is 160-180 ℃, and the screw rotation speed is 50-300 rpm.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, a specific kind of cross-linking agent is added into the formula to carry out pre-crosslinking modification on the cellulose acetate, and the transparency of a cellulose acetate product is greatly improved by utilizing the synergistic effect between the melting pre-crosslinking and the plasticizer, wherein the light transmittance of the cellulose acetate product is higher than 91.5 percent and can reach 93.7 percent at most; haze less than 5.0%; in addition, the addition of the cross-linking agent also obviously reduces the dosage of the plasticizer and reduces the risk of precipitation of the plasticizer; in addition, the cross-linking agent is added, only a simple heating pre-crosslinking modification process is needed, the time consumption is short, the process can be carried out in a common oven, and a curing process which is as long as 24 hours in the existing process is avoided, so that the production efficiency is greatly improved, and the requirements of large-scale industrial production are met.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1

100 parts of cellulose acetate (Wuhanpeng base biotechnology, Inc.), 20 parts of plasticizer triphenyl phosphate (Adamas, RG), 1 part of cross-linking agent triglycidyl isocyanurate (Guangzhou macro-biotechnology, Inc.), 0.3 part of antioxidant beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) n-octadecyl propionate (Pasf, Irganox1076) and 0.3 part of lubricant erucamide (Adamas, RG) are respectively weighed and added into a high-speed mixer to be uniformly mixed, and then, putting the uniformly mixed raw materials into an oven for processing at 110 ℃ for 2h, then extruding and granulating on a screw extruder, wherein the temperature of a first area is 160 ℃, the temperature of a second area is 170 ℃, the temperature of a third area is 170 ℃, the temperature of a fourth area is 170 ℃, the temperature of a fifth area is 170 ℃, the temperature of a sixth area is 175 ℃, the temperature of a seventh area is 175 ℃, the temperature of an eighth area is 175 ℃, the temperature of a ninth area is 175 ℃, the temperature of a die head is 180 ℃, and the particles are dried to obtain the high-transparency cellulose acetate material.

Example 2

Respectively weighing 100 parts of cellulose acetate (Wuhanpeng base Biotech Co., Ltd.), 18 parts of plasticizer glyceryl triacetate (Shandong Yousio chemical Co., Ltd.), 1 part of cross-linking agent succinic anhydride (Adamas, RG), 0.3 part of antioxidant tetra (beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid) pentaerythritol ester (Pasteur, Irganox1010), 0.3 part of lubricant erucamide (Adamas, RG) and 0.1 part of nucleating agent ethylene bis stearamide (Adamas, RG) into a high-speed mixer, uniformly mixing, placing the uniformly mixed raw materials into an oven for processing at 120 ℃ for 2h, then extruding and granulating on a screw extruder, wherein the first zone temperature is 160 ℃, the second zone temperature is 170 ℃, the fourth zone temperature is 170 ℃, the fifth zone temperature is 170 ℃, the sixth zone temperature is 175 ℃, the seventh zone temperature is 175 ℃, the eighth zone temperature is 175 ℃ and the ninth zone temperature is 175 ℃, the temperature of the die head is 180 ℃, and the high-transparency cellulose acetate material is obtained after the particles are dried.

Example 3

The preparation process was essentially the same as in example 2, except that the crosslinker succinic anhydride was replaced with triallyl isocyanurate (Guangzhou macro-Biotech Co., Ltd.).

Example 4

The procedure was essentially the same as in example 2, except that the crosslinker succinic anhydride was replaced with 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane (aksu, Trigonox 101).

Example 5

100 parts of cellulose acetate, 10 parts of plasticizer triphenyl phosphite (Adamas, RG), 10 parts of plasticizer triethyl citrate (Adamas, RG), 1.2 parts of cross-linking agent maleic anhydride (Adamas, RG), 0.3 part of antioxidant beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) n-octadecyl propionate (Pasf, Irganox1076) and 0.3 part of lubricant oleamide (Adamas, RG) are respectively weighed and added into a high-speed mixer to be uniformly mixed, and then, putting the uniformly mixed raw materials into an oven for processing for 3 hours at 110 ℃, then extruding and granulating on a screw extruder, wherein the temperature of a first area is 160 ℃, the temperature of a second area is 170 ℃, the temperature of a third area is 170 ℃, the temperature of a fourth area is 170 ℃, the temperature of a fifth area is 170 ℃, the temperature of a sixth area is 175 ℃, the temperature of a seventh area is 175 ℃, the temperature of an eighth area is 175 ℃, the temperature of a ninth area is 175 ℃, the temperature of a die head is 180 ℃, and the particles are dried to obtain the high-transparency cellulose acetate material.

Example 6

100 parts of cellulose acetate, 22 parts of plasticizer acetyl tributyl citrate (Shandong Youso chemical technology Co., Ltd.), 0.5 part of cross-linking agent 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane (Acksu, Trigonox 101), 0.3 part of antioxidant tris (2, 4-di-tert-butylphenyl) phosphite (Pasteur, Irganox168) and 0.3 part of lubricant pentaerythritol stearate (TCI, RG) are respectively weighed and added into a high-speed mixer to be uniformly mixed, and then, putting the uniformly mixed raw materials into an oven for processing for 3 hours at 110 ℃, then extruding and granulating on a screw extruder, wherein the temperature of a first area is 160 ℃, the temperature of a second area is 170 ℃, the temperature of a third area is 170 ℃, the temperature of a fourth area is 170 ℃, the temperature of a fifth area is 170 ℃, the temperature of a sixth area is 175 ℃, the temperature of a seventh area is 175 ℃, the temperature of an eighth area is 175 ℃, the temperature of a ninth area is 175 ℃, the temperature of a die head is 180 ℃, and the particles are dried to obtain the high-transparency cellulose acetate material.

Comparative example 1

The preparation process is similar to that of example 1, except that no crosslinker is added to the raw material composition.

And extruding and granulating on a screw extruder to obtain the material which is dark yellow, opaque and high in haze. The cellulose acetate is not subjected to melting pre-crosslinking treatment, the cellulose acetate is insufficient in plasticity due to insufficient addition of the plasticizer under the condition, and the product is yellow and opaque due to severe degradation during extrusion granulation.

Comparative example 2

The preparation process is similar to that of example 1, except that no plasticizer is added to the raw material composition. When the materials are extruded and granulated on a screw extruder, the motor is overloaded due to insufficient melting of the materials, and the materials cannot be extruded smoothly when the temperature is raised to over 240 ℃.

As can be seen by combining comparative example 1 and comparative example 2, the preparation process of the present invention is achieved under the synergistic effect of melt pre-crosslinking and plasticizer.

Comparative example 3

The preparation process is similar to that of example 1, except that phthalic anhydride (Adamas, RG) is used as the crosslinking agent.

And extruding and granulating on a screw extruder to obtain the material which is dark yellow, opaque and high in haze. Phthalic anhydride, because of its high melting point (130.8 ℃), does not melt at 110 ℃ and thus does not undergo a crosslinking reaction during the heat treatment process. Under the test conditions, the plasticizer is not added enough to ensure that the cellulose acetate molecules obtain enough motion capability, and the cellulose acetate molecules are seriously decomposed in the melt processing process, so that the product is yellow and has low transparency.

Comparative example 4

The preparation process is similar to that of example 1, except that ethylene glycol diglycidyl ether (Adamas, RG) is used as crosslinker.

And extruding and granulating on a screw extruder to obtain the material which is dark yellow, opaque and high in haze. Although the melting point of ethylene glycol diglycidyl ether is low, it requires a high temperature (200 ℃ or higher) when it reacts with cellulose acetate, and therefore, it cannot sufficiently undergo a crosslinking reaction with cellulose acetate during heat treatment or in a screw. Under the test conditions, the plasticizer is not added enough to ensure that the cellulose acetate molecules obtain enough motion capability, and the cellulose acetate molecules are seriously decomposed in the melt processing process, so that the product is yellow and has low transparency.

The materials prepared in the above groups of examples and comparative examples were injection molded to obtain 50mm × 50mm sheets, and the yellow index, transmittance and haze of each sample were measured according to the methods specified in HG/T3862-2006 plastic yellow index test method and GB/T2410-2008 determination of transmittance and haze of transparent plastic, and the test results of each group of samples are shown in table 1. The mechanical properties of the samples were tested according to the methods specified in GB/T1040-92 test methods for tensile properties of plastics and GB/T9341-2008 determination of bending properties of plastics, and the test results are shown in Table 2.

TABLE 1

TABLE 2

The above examples are preferred embodiments of the present invention, but the present invention is not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such modifications are intended to be included in the scope of the present invention.