阅读说明：本技术 一种制备介质滤波器陶瓷制品用的注射成型粘结剂及其应用 (Injection molding binder for preparing dielectric filter ceramic product and application thereof ) 是由 刘子峰 陈晓敏 王文利 王娜娜 丛涛 贺琰 于 2020-05-21 设计创作，主要内容包括：本发明公开了一种制备介质滤波器陶瓷制品用的注射成型粘结剂及其应用,包括树脂组分,树脂组分包括投料质量比为5-12∶1∶0.4-2∶1-3的聚甲醛、非极性聚合物、聚丙烯酸树脂和乙烯-醋酸乙烯酯共聚物；以质量百分含量计,聚甲醛占粘结剂的50-60%；及由前述粘结剂与陶瓷粉末混合制成的制备介质滤波器陶瓷制品用的喂料混合物；及采用前述喂料混合物挤出造粒制成的制备介质滤波器陶瓷制品用的颗粒物；及采用前述颗粒物制成的介质滤波器陶瓷制品,尤其是5G介质陶瓷滤波器；本发明能够有效改善喂料的流动性,提升亚微米陶瓷粉末的固含量,脱脂效率高且速度快,尤其适用于大尺寸、复杂陶瓷制品例如5G介质陶瓷滤波器的制备。(The invention discloses an injection molding adhesive for preparing a dielectric filter ceramic product and application thereof, wherein the adhesive comprises resin components, wherein the resin components comprise polyformaldehyde, a nonpolar polymer, polyacrylic resin and an ethylene-vinyl acetate copolymer, wherein the feeding mass ratio of the polyformaldehyde to the nonpolar polymer to the polypropylene resin is 5-12: 1: 0.4-2: 1-3; the polyformaldehyde accounts for 50-60% of the binder by mass percentage; and a feeding mixture for preparing the ceramic product of the dielectric filter, which is prepared by mixing the binder and the ceramic powder; and the particles for preparing the ceramic product of the dielectric filter are prepared by adopting the extrusion granulation of the feeding mixture; and a dielectric filter ceramic product made of the particles, especially a 5G dielectric ceramic filter; the invention can effectively improve the fluidity of the feed, improves the solid content of the submicron ceramic powder, has high degreasing efficiency and high speed, and is particularly suitable for preparing large-size and complex ceramic products such as 5G dielectric ceramic filters.)

1. An injection molding adhesive for preparing a dielectric filter ceramic product, which comprises a resin component, and is characterized in that the resin component comprises polyformaldehyde, a nonpolar polymer, polyacrylic resin and an ethylene-vinyl acetate copolymer, wherein the mass ratio of the polyformaldehyde to the nonpolar polymer to the polyacrylic resin to the ethylene-vinyl acetate copolymer is 5-12: 1: 0.4-2: 1-3; wherein, the polyformaldehyde accounts for 50-60% of the binder in the binder by mass percentage.

2. The injection-molding binder for producing a dielectric filter ceramic article according to claim 1, wherein the decomposition temperature of the polyacrylic acid resin, the decomposition temperature of the ethylene-vinyl acetate copolymer, and the decomposition temperature of the nonpolar polymer are sequentially distributed in a stepwise manner.

3. The injection-molded binder for ceramic dielectric filter products according to claim 1, wherein the total amount of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer is 15% or more of the binder.

4. The injection-molded binder for ceramic dielectric filter products according to claim 3, wherein the total amount of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer is 20% or more of the binder.

5. The injection-molded binder for ceramic dielectric filters according to claim 4, wherein the total amount of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer is greater than 24% of the binder.

6. The injection molding adhesive for preparing the ceramic dielectric filter product as claimed in claim 1, wherein the non-polar polymer accounts for 5-10% of the adhesive, the polyacrylic resin accounts for 4-10% of the adhesive, and the ethylene-vinyl acetate copolymer accounts for 10-15% of the adhesive.

7. The injection molding adhesive for preparing the dielectric filter ceramic product according to claim 1, wherein the polyformaldehyde is homo-polyformaldehyde with a melt index of 70-90 g/10 min; and/or the melt index of the non-polar polymer is 3-15 g/10 min; and/or the content of vinyl acetate in the ethylene-vinyl acetate copolymer is below 20 percent; and/or the molecular weight of the polyacrylic resin is 1.6-4.5W.

8. The injection-molded binder for producing a dielectric filter ceramic article according to claim 1, wherein the nonpolar polymer is one or a combination of two or a combination of three selected from the group consisting of high-density polyethylene, polypropylene and polystyrene.

9. The injection-molded binder for producing a dielectric filter ceramic article according to claim 1, wherein the binder further comprises auxiliaries comprising a lubricant, a surfactant and a plasticizer;

the adhesive comprises the following components in percentage by mass: 50-60% of polyformaldehyde, 5-10% of nonpolar polymer, 4-10% of polyacrylic resin, 10-15% of ethylene-vinyl acetate copolymer, 5-12% of lubricant, 3-8% of surfactant and 2-6% of plasticizer.

10. The injection molding binder for manufacturing a dielectric filter ceramic article according to claim 9, wherein the lubricant comprises paraffin wax and/or microcrystalline wax, the surfactant comprises zinc stearate and/or sodium stearate, and the plasticizer comprises dioctyl phthalate and/or dibutyl phthalate.

11. A feed mixture for manufacturing dielectric filter ceramic ware, wherein the feed mixture is prepared by mixing the injection molding binder for manufacturing dielectric filter ceramic ware according to any one of claims 1 to 10 with dielectric ceramic powder.

12. The feed mixture for the preparation of ceramic dielectric filter products as set forth in claim 11, wherein said dielectric ceramic powder has an average particle size of 0.3 to 2.0 μm.

13. The feed mixture for the preparation of dielectric filter ceramic ware as claimed in claim 11 or 12, wherein the dielectric ceramic powder is 79-85% by mass of the feed mixture.

14. The feed mixture for the preparation of ceramic dielectric filters as set forth in claim 11, wherein the feed mixture is prepared by mixing and melting polyoxymethylene, a non-polar polymer, a polyacrylic resin, and an ethylene-vinyl acetate copolymer contained in the binder, adding the remaining components, mixing and kneading.

15. A pellet for manufacturing a dielectric filter ceramic article, wherein the pellet is prepared by extrusion granulation using the feed mixture for manufacturing a dielectric filter ceramic article according to any one of claims 11 to 14.

16. A dielectric filter ceramic article, which is produced by injection-molding the particulate matter according to claim 15 into a green body, and then subjecting the green body to catalytic degreasing, thermal degreasing, and sintering molding in this order.

17. The dielectric filter ceramic article of claim 16, wherein the catalytic degreasing is performed at a temperature of 120 ℃ and 130 ℃ in an acidic catalytic atmosphere.

18. The dielectric filter ceramic article of claim 17, wherein the acidic catalytic atmosphere is formed using oxalic acid.

19. The dielectric filter ceramic article of claim 16, wherein the thermal degreasing is performed in a stepwise manner from room temperature to 800 ℃, wherein each stage is maintained or not maintained.

20. The dielectric filter ceramic article of claim 19, wherein the phased ramp up comprises the following stages:

stage one: heating to 170 ℃ from room temperature at the speed of 1-2 ℃/min;

and a second stage: heating to 250 deg.C at a rate of 0.3-0.8 deg.C/min from 170 deg.C, and maintaining;

and a third stage: heating from 250 deg.C to 350 deg.C at a rate of 0.3-0.8 deg.C/min, and maintaining;

and a fourth stage: heating from 350 deg.C to 500 deg.C at a rate of 0.5-1.5 deg.C/min, and maintaining;

and a fifth stage: heating to 800 deg.C from 500 deg.C at a rate of 1-2 deg.C/min, and maintaining the temperature.

21. The dielectric filter ceramic article of claim 16, wherein the sintering temperature for the sintering molding is 1300-1400 ℃.

22. A dielectric filter ceramic article according to any one of claims 16 to 21, which is a 5G dielectric ceramic filter.

Technical Field

The invention belongs to the field of functional ceramic materials, in particular to application of functional ceramics in the field of electronic components, mainly adopts an injection molding mode to prepare a near-net-size filter ceramic product, and particularly relates to an injection molding binder for preparing a dielectric filter ceramic product and application thereof.

Background

The functional ceramic product is prepared by dry pressing, wherein the method comprises the steps of putting granulated powder into a die cavity, pressing the powder into a required shape by up-and-down pressing, and is limited by the pressing method. In addition, due to the vertical pressing mode of dry pressing, pressure distribution and density inside the blank are uneven during forming, so that the sintered product shrinks unevenly, deforms and affects the yield, and therefore, the forming process is not suitable for batch production of ceramic products with high precision requirements.

With the development of 5G technology, the application and the demand of functional ceramics in the fields of electronic components and communication are more and more, the structural requirements on products are more and more complex, especially in the product structure of 5G dielectric ceramic filter products, complex structures such as multiple holes, grooves, steps, micropores and the like exist, and the requirements for the dimensional accuracy and performance of ceramic products are getting higher and higher, especially for the dielectric ceramic filter used on the base station, the above traditional dry pressing forming mode can not meet the current product requirements, a near-net-size preparation technology of ceramic products needs to be developed, the ceramic powder injection forming technology is a more ideal process technology for solving the problem, among them, the binder system used in the injection molding of ceramic powder is one of the more critical technologies, which can determine the performance of the ceramic product to some extent.

Currently, most of the binder systems used for ceramic powder injection molding are wax-based binder systems, and generally the systems contain at least 30% or more of low molecular wax components, and further contain a polymer resin skeleton component and a small amount of dispersant components. After mixing with the powder and injection molding, wax components are dissolved and removed by a solvent degreasing mode, and then residual organic components are removed by thermal degreasing. This binder system has good feed flow properties but suffers from the following disadvantages: 1) the bonding of the binder and the powder is poor, and injection molding defects such as welding lines, bubbling and the like are easily generated during injection molding, so that the performance of a sintered product is influenced; especially when manufacturing products with large size and wall thickness, the injection molding defect is more obvious and can not be eliminated; 2) solvent degreasing is adopted, so that the degreasing efficiency is low, most of waxes can be removed within 2-3 days generally, and the adopted organic solvent is not environment-friendly; 3) the green body is soaked in an organic solvent for a long time, and is easy to swell to cause deformation and even cracking of the green body. The binder system is therefore not well suited for the preparation of large-size, complex ceramic articles.

The other adhesive system for preparing ceramic products with less application is a direct thermal degreasing type, a plurality of polar and nonpolar long-chain organic resin components are integrated in an adhesive formula, the content of wax components is low, the melting index of the resins is generally high, the melting point is low, the prepared feeding fluidity is good, the strength of a molded green body is high, the direct thermal degreasing can be carried out, and different organic resins have different decomposition temperatures during the thermal degreasing and can be removed in stages. The process is suitable for small-size products, and because the direct thermal degreasing mode is adopted to remove the adhesive, the thermal degreasing time is generally longer, more than 3 days, for large-size wall-thickness products, the adhesive is difficult to discharge, the process time is long, and the process is not suitable for mass production. For example, chinese patent CN 109748592a discloses a binder degreased by heating, which comprises the following components in parts by weight: 1-50 parts of acrylic acid; 1-10 parts of polyurethane; 1-50 parts of methyl methacrylate; 1-10 parts of butadiene; 1-50 parts of styrene; 1-50 parts of rosin oil; 1-30 parts of paraffin; 1-30 parts of microcrystalline wax; 1-30 parts of stearic acid; 1-30 parts of oleic acid. The patent requires heating for 56-96 hours to discharge organic matters, takes long time and has cracking phenomenon caused by overlong heating time.

The catalytic degreasing type adhesive is applied to metal powder molding more, polyformaldehyde is used as a main component of the adhesive, the proportion is generally more than 70%, POM (polyformaldehyde) resin has lower melt index and poorer fluidity, the adhesive prepared by the system is often poor in fluidity and is applied to metal powder injection molding, the solid content can reach 90% due to the larger granularity of the metal powder, 1-1000 mu m, but the ceramic product has high requirements on the performance relative to metal products, so that uniform submicron functional ceramic powder is required to be used in raw material selection, the granularity of the ceramic powder is generally 0.3-2 mu m, for products with high precision and high performance requirements, the used ceramic powder is even in a nanometer level, the powder granularity is smaller, the particle comparative area is larger, and when the POM system is adopted for mixing, feeding with proper fluidity and solid content is often unavailable, therefore, the catalytic degreasing binder is not widely applied to injection molding of submicron ceramic powder.

For example, chinese patent CN 101353561a discloses a catalytic degreasing binder suitable for injection molding of zirconia ceramic powder, which is composed of the following components (volume percent): 90% of polyoxymethylene homopolymer 500P, 4% of high-density polyethylene, 3% of paraffin wax, 1% of ethylene-vinyl acetate copolymer (EVA) with the Vinyl Acetate (VA) content of 24, 1.5% of dibutyl phthalate and 0.5% of zinc stearate. The preparation method of this example: (1) 90% of homo-polyformaldehyde 500P, 4% of high-density polyethylene, 1% of ethylene-vinyl acetate copolymer (EVA) with the Vinyl Acetate (VA) content of 24 and 53% of zirconia ceramic powder with the powder loading are added into a three-dimensional rotator and are dry-mixed for 1 hour to obtain a uniform mixture of powder and a binder. (2) Adding the uniform mixture into an internal mixer, heating to 190 ℃, and mixing for 25 minutes. (3) The mixing temperature is reduced to 165 ℃, then 3 percent of paraffin, 1.5 percent of dibutyl phthalate and 0.5 percent of stearic acid are added into an internal mixer and mixed for 30 minutes to prepare the catalytic degreasing zirconia ceramic feed. Although the patent can realize better rheological property on the premise of 50-68% of powder loading, in the practical application of injection molding of the dielectric ceramic powder, the powder granularity is small, the viscosity and the strength of POM are high, and the POM is difficult to be uniformly mixed, and the sintered dielectric filter ceramic product is prone to deformation, has many internal porosity and other problems, so that the size and the dielectric property of the sintered dielectric ceramic product are difficult to meet the application requirements of the filter product.

Disclosure of Invention

The invention aims to overcome one or more defects in the prior art, and provides an improved injection molding adhesive for preparing ceramic products of dielectric filters, which can effectively improve the flowability of feeding materials, increase the solid content of submicron ceramic powder, has high degreasing efficiency and high degreasing speed, and is particularly suitable for preparing large-size and complex ceramic products such as 5G dielectric ceramic filters.

The invention also provides a feeding mixture prepared by the binder for preparing the dielectric filter ceramic product.

The invention also provides a particle prepared from the feed mixture and used for preparing the dielectric filter ceramic product.

The invention also provides a dielectric filter ceramic product made of the particles, and the dielectric filter ceramic product comprises a 5G dielectric ceramic filter.

In order to achieve the purpose, the invention adopts a technical scheme that:

an injection molding adhesive for preparing a dielectric filter ceramic product, which comprises a resin component, wherein the resin component comprises polyformaldehyde, a nonpolar polymer, polyacrylic resin and an ethylene-vinyl acetate copolymer, and the mass ratio of the polyformaldehyde to the nonpolar polymer to the polyacrylic resin to the ethylene-vinyl acetate copolymer is 5-12: 1: 0.4-2: 1-3; wherein, the polyformaldehyde accounts for 50-60% of the binder in the binder by mass percentage.

According to the invention, the decomposition temperature of the polyacrylic resin, the decomposition temperature of the ethylene-vinyl acetate copolymer and the decomposition temperature of the nonpolar polymer are sequentially distributed in a gradient manner.

According to some preferred aspects of the invention, the total charge of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer is more than 15% of the binder.

More preferably, the total dosage of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer is more than 20% of the binder.

Further preferably, the total dosage of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer accounts for more than 24% of the binder.

According to some preferred aspects of the present invention, the amount of the non-polar polymer in the adhesive is 5-10% of the amount of the adhesive, the amount of the polyacrylic resin is 4-10% of the amount of the adhesive, and the amount of the ethylene-vinyl acetate copolymer is 10-15% of the amount of the adhesive.

According to some preferred and specific aspects of the invention, the polyoxymethylene is a homopolyformaldehyde having a melt index of 70 to 90g/10min (measured according to ISO1133 standard).

According to some preferred and specific aspects of the present invention, the non-polar polymer may be one or a mixture of HDPE, PP, PS, having a melt index of 3 to 15g/10min (measured according to ISO1133 standard).

According to some preferred aspects of the present invention, the non-polar polymer is one or a combination of two or a combination of three selected from high density polyethylene, polypropylene and polystyrene, including but not limited to high density polyethylene, polypropylene, polystyrene or a combination of high density polyethylene and polypropylene, which can be combined in a feed mass ratio of 1: 0.1-10; or a combination of high density polyethylene and polystyrene, which can be combined in a feed mass ratio of 1: 0.1-10; (ii) a Or a combination of polypropylene and polystyrene, which can be combined in a feed mass ratio of 1: 0.1-10; or the combination of high-density polyethylene, polypropylene and polystyrene, and the three can be combined according to the feeding mass ratio of 1: 0.1-10.

According to some preferred and specific aspects of the present invention, the ethylene-vinyl acetate copolymer has a vinyl acetate content of 20% or less.

According to some preferred and specific aspects of the present invention, the polyacrylic resin has a molecular weight of 1.6 to 4.5W.

According to some specific and preferred aspects of the present invention, the binder further comprises adjuvants including lubricants, surfactants, and plasticizers;

the adhesive comprises the following components in percentage by mass: 50-60% of polyformaldehyde, 5-10% of nonpolar polymer, 4-10% of polyacrylic resin, 10-15% of ethylene-vinyl acetate copolymer, 5-12% of lubricant, 3-8% of surfactant and 2-6% of plasticizer.

According to some specific aspects of the invention, the lubricant comprises paraffin wax and/or microcrystalline wax, the surfactant comprises zinc stearate and/or sodium stearate, and the plasticizer comprises dioctyl phthalate and/or dibutyl phthalate.

The invention provides another technical scheme that: a feed mixture for preparing dielectric filter ceramic products is prepared by mixing the injection molding binder for preparing the dielectric filter ceramic products with dielectric ceramic powder.

According to the invention, the mean particle size of the dielectric ceramic powder is between 0.3 and 2.0. mu.m.

According to some preferred aspects of the invention, the dielectric ceramic powder comprises 79-85% by mass of the feed mixture.

According to some preferred aspects of the present invention, the feed mixture is prepared by mixing, banburying and melting polyoxymethylene, a non-polar polymer, a polyacrylic resin, and an ethylene-vinyl acetate copolymer contained in the binder, adding the remaining components, banburying and kneading.

The invention provides another technical scheme that: the granular material for preparing the dielectric filter ceramic product is prepared by extruding and granulating the feed mixture for preparing the dielectric filter ceramic product.

The invention provides another technical scheme that: a dielectric filter ceramic product is prepared by preparing a green body from the particles through injection molding, and then sequentially carrying out catalytic degreasing, thermal degreasing and sintering molding on the green body to prepare the ceramic product.

According to some preferred aspects of the invention, the catalytic degreasing is carried out under an acidic catalytic atmosphere at a temperature of 120-130 ℃.

According to some specific aspects of the invention, the acidic catalytic atmosphere is formed using oxalic acid.

According to some preferred aspects of the invention, the thermal degreasing is performed by heating from room temperature to 800 ℃ in stages, wherein each stage is maintained or not maintained.

According to some preferred aspects of the invention, the staged temperature increase comprises the following stages:

stage one: heating to 170 ℃ from room temperature at the speed of 1-2 ℃/min;

and a second stage: heating to 250 deg.C at a rate of 0.3-0.8 deg.C/min from 170 deg.C, and maintaining;

and a third stage: heating from 250 deg.C to 350 deg.C at a rate of 0.3-0.8 deg.C/min, and maintaining;

and a fourth stage: heating from 350 deg.C to 500 deg.C at a rate of 0.5-1.5 deg.C/min, and maintaining;

and a fifth stage: heating to 800 deg.C from 500 deg.C at a rate of 1-2 deg.C/min, and maintaining the temperature.

According to some preferred aspects of the invention, the sintering temperature for sintering and forming is 1300-1400 ℃.

According to a preferred application aspect of the present invention, the dielectric ceramic filter is a 5G dielectric ceramic filter.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

the invention innovatively adopts four specific polymers to jointly form the resin component for the binder, and simultaneously limits the content of polyformaldehyde in the binder and the relative content of the resin components, so that the prepared binder can be suitable for molding of special-shaped parts of submicron ceramic powder, and the prepared binder can still obtain excellent fluidity even under the premise of a mixed system with high solid content (more than 85%) in the preparation process after the two are combined, the prepared parts have good size and high precision, secondary processing is not needed, the production cost is reduced, particularly, the mechanical property and the dielectric property of the prepared ceramic product are excellent, and the requirements of large-size and complex ceramic products such as 5G dielectric ceramic filters are met.

Detailed Description

With the vigorous development of the high and new technology industry of society, the 5G technology comes up, and with the development of the 5G technology, the application and the demand of functional ceramics in the fields of electronic components and communication are more and more increased, the structural requirements on products are more and more complex, the product structure can have various complex structures such as a plurality of holes, grooves, steps, micropores and the like, and the dimensional precision and the performance requirements on ceramic products are more and more high, in particular to a dielectric ceramic filter used on a base station, the traditional dry pressing forming mode can not meet the requirements of the current products, a near-net-size preparation technology of the ceramic products needs to be developed, and a ceramic powder injection forming technology is an ideal process technology for solving the problem. However, the high performance requirements of the dielectric ceramic product relative to the metal product make it necessary to use uniform submicron powder for raw material selection, and the combination of the submicron ceramic powder and the injection molding technology does not solve the problems of low fluidity and solid content at present, and thus the ceramic product which is difficult to be made or made exists more or less: the preparation period is long, the product is easy to deform, the injection molding is easy to crack, and the dielectric property, the mechanical property and the like do not meet the requirements, and the like.

Based on the above problems, the present inventors have long practiced and have innovatively proposed an improved injection molding binder for preparing dielectric filter ceramic articles, it can effectively improve the fluidity of a mixing system (the mixing of a binder and dielectric ceramic powder), improve the solid content of submicron ceramic powder, during the preparation process, the polyformaldehyde can be quickly removed firstly in a catalytic degreasing mode, communicated pore channels are formed in the blank body, and then the pore channels are provided for the subsequent thermal degreasing of the residual binder, the invention adopts polyacrylic resin, ethylene-vinyl acetate copolymer and non-polar polymer with gradient distribution of decomposition temperature to compound, so that on one hand, the prepared adhesive and the dielectric ceramic powder have good dispersibility, wettability and adsorbability, the dielectric ceramic powder is not easy to agglomerate, the mixed material has good fluidity and high solid content; on the other hand, through a staged degreasing mode, the green body is not easy to deform, the shape retention is good, the prepared product has high precision, the product can be prevented from cracking, the prepared feed has good fluidity, and the demoulding is easy to realize during injection molding; the prepared dielectric filter ceramic product has better mechanical property and excellent electrical property.

Specifically, the invention provides an injection molding adhesive for preparing a dielectric filter ceramic product, which comprises a resin component, wherein the resin component comprises polyformaldehyde, a nonpolar polymer, polyacrylic resin and an ethylene-vinyl acetate copolymer, and the mass ratio of the polyformaldehyde to the nonpolar polymer to the polyacrylic resin to the ethylene-vinyl acetate copolymer is 5-12: 1: 0.4-2: 1-3; wherein, the polyformaldehyde accounts for 50-60% of the binder in the binder by mass percentage.

According to the invention, the decomposition temperature of the polyacrylic resin, the decomposition temperature of the ethylene-vinyl acetate copolymer and the decomposition temperature of the nonpolar polymer are sequentially distributed in a gradient manner.

In some preferred embodiments of the present invention, the total charge of the polyacrylic resin, the ethylene-vinyl acetate copolymer, and the non-polar polymer is greater than 15% of the binder. More preferably, the total dosage of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer is more than 20% of the binder. Further preferably, the total dosage of the polyacrylic resin, the ethylene-vinyl acetate copolymer and the non-polar polymer accounts for more than 24% of the binder.

In some preferred embodiments of the present invention, the amount of the non-polar polymer in the adhesive is 5-10 wt%, the amount of the polyacrylic resin is 4-10 wt%, and the amount of the ethylene-vinyl acetate copolymer is 10-15 wt%.

In some preferred embodiments of the invention, the polyoxymethylene is a homopolyformaldehyde having a melt index of 70 to 90g/10min (according to ISO1133 standard), the non-polar polymer has a melt index of 3 to 15g/10min (according to ISO1133 standard), and the non-polar polymer is one or a combination of two or a combination of three selected from high density polyethylene, polypropylene and polystyrene, including but not limited to high density polyethylene, polypropylene, polystyrene, or a combination of high density polyethylene and polypropylene, which may be combined in a feed mass ratio of 1: 0.1-10; or a combination of high density polyethylene and polystyrene, which can be combined in a feed mass ratio of 1: 0.1-10; or a combination of polypropylene and polystyrene, which can be combined in a feed mass ratio of 1: 0.1-10; or the combination of high-density polyethylene, polypropylene and polystyrene, and the three can be combined according to the feeding mass ratio of 1: 0.1-10.

In some preferred embodiments of the present invention, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is less than 20%, and the molecular weight of the polyacrylic resin is 1.6-4.5W.

In some preferred embodiments of the present invention, the binder further comprises adjuvants including lubricants, surfactants, and plasticizers; the adhesive comprises the following components in percentage by mass: 50-60% of polyformaldehyde, 5-10% of non-polar polymer, 4-10% of polyacrylic resin, 10-15% of ethylene-vinyl acetate copolymer, 5-12% of lubricant, 3-8% of surfactant and 2-6% of plasticizer, wherein the lubricant comprises paraffin wax and/or microcrystalline wax, the surfactant comprises zinc stearate and/or sodium stearate, and the plasticizer comprises dioctyl phthalate (DOP) and/or dibutyl phthalate (DBP).

A feed mixture for preparing dielectric filter ceramic products is prepared by mixing the injection molding binder for preparing the dielectric filter ceramic products with dielectric ceramic powder.

According to the invention, the mean particle size of the dielectric ceramic powder is between 0.3 and 2.0. mu.m.

In some preferred embodiments of the invention, the dielectric ceramic powder comprises 79-85% by mass of the feed mixture.

The feeding mixture is prepared by mixing, banburying and melting polyformaldehyde, nonpolar polymer, polyacrylic resin and ethylene-vinyl acetate copolymer contained in the binder, adding the rest components, banburying and kneading.

The granular material for preparing the dielectric filter ceramic product is prepared by extruding and granulating the feed mixture for preparing the dielectric filter ceramic product.

A dielectric filter ceramic product is prepared by preparing a green body from the particles through injection molding, and then sequentially carrying out catalytic degreasing, thermal degreasing and sintering molding on the green body to prepare the ceramic product.

In some preferred embodiments of the present invention, the catalytic degreasing is performed at a temperature of 120 ℃. about.130 ℃ in an acidic catalytic atmosphere formed by oxalic acid, the generated formaldehyde gas can be directly ignited to burn and eliminate, and the removal rate of the POM is above 93%.

In some preferred embodiments of the present invention, the thermal degreasing is performed by a staged heating method, wherein the temperature is increased from room temperature to 800 ℃, and each stage is kept or not kept, and the staged heating method comprises the following stages: stage one: heating to 170 ℃ from room temperature at the speed of 1-2 ℃/min; and a second stage: heating to 250 deg.C at a rate of 0.3-0.8 deg.C/min from 170 deg.C, and maintaining; and a third stage: heating from 250 deg.C to 350 deg.C at a rate of 0.3-0.8 deg.C/min, and maintaining; and a fourth stage: heating from 350 deg.C to 500 deg.C at a rate of 0.5-1.5 deg.C/min, and maintaining; and a fifth stage: heating to 800 deg.C from 500 deg.C at a rate of 1-2 deg.C/min, and maintaining the temperature.

In some preferred embodiments of the present invention, the sintering temperature for the sintering and forming is 1300-1400 ℃.

According to a preferred application aspect of the present invention, the dielectric ceramic filter is a 5G dielectric ceramic filter.

The above-described scheme is further illustrated below with reference to specific examples; it is to be understood that these embodiments are provided to illustrate the general principles, essential features and advantages of the present invention, and the present invention is not limited in scope by the following embodiments; the implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not indicated are generally the conditions in routine experiments.

Not specifically illustrated in the following examples, all starting materials are commercially available or prepared by methods conventional in the art. The following polyformaldehyde was a homo-polyoxymethylene, available from Asahi Kasei K.K., No. 9054; polyacrylic resin, available from Mitsubishi, Japan, trade designation BR-116; EVA resin (VA content 18%), available from taiwan plastic of china, designation 7350M; high Density Polyethylene (HDPE) available from exxonmobil, trade name HTA001 HD; polypropylene, available from basf under the designation HP 500N; polystyrene, available from taiwan of china under the designation HD 8250.