CN115850621A - Copolymerized formaldehyde resin composition, metal resin composition taking same as raw material, and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of copolyoxymethylene resin, in particular to a copolyoxymethylene resin composition, a metal resin composition taking the copolyoxymethylene resin composition as a raw material, and a preparation method and application thereof. The raw materials of the polyformaldehyde resin comprise 70 to 100 parts of trioxymethylene, 0.01 to 5 parts of functional monomer, 0.01 to 5 parts of cyclic ether compound, 0.01 to 0.3 part of catalyst, 0.4 to 0.8 part of molecular weight regulator, 0.01 to 1 part of antioxidant, 0.01 to 0.5 part of heat stabilizer and 0.01 to 0.5 part of lubricant; the functional monomer is a cyclic ether compound with a long alkyl side chain. The method solves the technical problems of poor dispersion uniformity and non-ideal acidolysis rate of metal or ceramic components when a metal part is prepared by using the polyformaldehyde resin in the prior art by adding the cyclic ether compound with the long alkyl side chain, a specific heat stabilizer, controlling the melt index and the like, and has ideal application prospect.

Description

Copolymerized formaldehyde resin composition, metal resin composition taking same as raw material, and preparation method and application thereof

Technical Field

The invention relates to the technical field of co-polymer formaldehyde resin, in particular to a co-polymer formaldehyde resin composition, a metal resin composition taking the co-polymer formaldehyde resin composition as a raw material, and a preparation method and application of the metal resin composition.

Background

Polyoxymethylene homo-or copolymers, also known as polyacetals or polyoxymethylenes or POMs, are generally high molecular weight thermoplastic materials with high rigidity, low coefficients of friction and excellent dimensional and thermal stability. They are frequently used for the production of parts for precision engineering, automobiles, electronic equipment, electrical equipment, and the like.

Polyoxymethylene is easily decomposed in an acid environment, particularly, the decomposition speed is higher in the acid environment with higher temperature, and almost no residue is left after decomposition. The binder component for injection molding of metal powder or ceramic powder generally includes a skeleton binder, a filler, a compatibilizer, and the like. The skeletal binder is typically polyethylene, polypropylene, polystyrene, ethylene acrylic acid copolymer, PMMA, and the like. The filler is generally paraffin and polyformaldehyde, and the polyformaldehyde gradually replaces the paraffin to become the mainstream filler due to the advantages of production cost, environmental protection and the like. The compatibilizer is typically maleic anhydride, stearic acid, and the like. In addition, in the injection molding process of metal powder or ceramic powder, an antioxidant, a mold release agent, and the like are generally added. In the actual metal powder injection molding production process, the uniformity of feeding of the polyformaldehyde resin, the acidolysis rate of the polyformaldehyde resin and the dispersion degree of the metal powder in the polyformaldehyde resin are found to have great influence on the quality of metal parts and the production cost. The acidolysis rate of the polyformaldehyde resin is high, certain flow property is maintained, the metal powder can be fully dispersed, the quality of a metal part prepared by a metal powder injection molding process can be obviously improved, and meanwhile, the production cost is reduced.

Chinese patent CN105121488A discloses a polyoxymethylene copolymer and thermoplastic POM composition that improves the flowability of the body binder polyoxymethylene with lower molecular weight polyoxymethylene, thereby improving the flowability of the feed. However, although the fluidity of the polyoxymethylene resin is improved to a certain extent by adopting the above method, which is beneficial to feeding, the method does not show the effect of improving the dispersibility and the uniform dispersion degree of the metal powder in the polyoxymethylene resin, and further fails to realize the improvement of the acid hydrolysis rate of polyoxymethylene. Therefore, it is necessary to develop a polyoxymethylene resin with ideal flowability, sufficient dispersion of metal powder and increased acidolysis rate to meet the production requirements of metal parts.

Disclosure of Invention

The present invention is intended to provide a copolyoxymethylene resin composition for solving the technical problems of poor dispersion uniformity of metal or ceramic components and an unsatisfactory acid hydrolysis rate in the production of metal articles using a polyoxymethylene resin of the prior art.

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

the copolyoxyformaldehyde resin composition comprises the following raw materials in parts by weight: 70-100 parts of trioxymethylene, 0.01-5 parts of functional monomer, 0.01-5 parts of cyclic ether compound, 0.01-0.3 part of catalyst, 0.4-0.8 part of molecular weight regulator, 0.01-1 part of antioxidant, 0.01-0.5 part of heat stabilizer and 0.01-0.5 part of lubricant;

the functional monomer is a cyclic ether compound with a long alkyl side chain.

The invention also provides a preparation method of the copolyoxymethylene resin composition, which comprises the following steps in sequence:

s1: mixing a monomer, a functional monomer, a cyclic ether compound, a catalyst and a molecular weight regulator, and carrying out polymerization reaction to obtain a reaction product; crushing, deactivating, washing and drying the reaction product to obtain polyformaldehyde resin powder;

s2: mixing polyformaldehyde resin powder, an antioxidant, a heat stabilizer and a lubricant, performing extrusion granulation, and performing granulation and drying to obtain polyformaldehyde resin granules; the melt index of the polyformaldehyde resin pellets is 100-220g/min.

The invention also provides a metal/ceramic resin composition prepared from the copolyformaldehyde resin composition, which comprises the following raw materials in parts by weight of 70-95% of main material powder and 5-30% of adhesive system in percentage by weight;

the main material powder comprises metal powder and/or ceramic powder; the raw material of the metal powder comprises at least one of simple metal, metal compound and metal alloy of aluminum, magnesium, barium, calcium, cobalt, zinc, copper, nickel, iron, silicon, titanium, tungsten and zirconium; the raw material of the ceramic powder includes at least one of an oxide, a hydroxide, a carbide, a nitride, a halide, a titanate, a carbonate, a phosphate, and a high-temperature superconductor;

the adhesive system comprises the following components in a mass ratio of 80-90:9-20:0.5-1.5 of polyformaldehyde resin granules, a skeleton binding agent and a compatilizer.

Further, the cyclic ether compound includes at least one of ethylene oxide, propylene oxide, butylene oxide, 3-chloro-1, 2-propylene oxide, 3-bromo-1, 2-propylene oxide, styrene oxide, oxetane, 3-bis (chloromethyl) oxetane, tetrahydrofuran, 1, 3-dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1, 4-butanediol formal, 1, 5-pentanediol formal, and 1, 6-hexanediol formal.

Further, the functional monomers include 1, 2-epoxyhexane, 1, 2-epoxydecane, 1, 2-epoxydodecane, 1, 2-epoxyoctadecane, 1, 2-epoxyeicosane; 4-pentyl-1, 3-dioxolane, 4-hexyl-1, 3-dioxolane, 4-decyl-1, 3-dioxolane, 4-dodecyl-1, 3-dioxolane, 4-octadecyl-1, 3-dioxolane, 4-eicosyl-1, 3-dioxolane. Preferably 1, 2-epoxydodecane, 1, 2-epoxyoctadecane, 1, 2-epoxyeicosane; 4-dodecyl-1, 3-dioxygen pentacyclic, 4-octadecyl-1, 3-dioxygen pentacyclic and 4-eicosyl-1, 3-dioxygen pentacyclic.

Further, the catalyst includes at least one of lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, antimony pentafluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl ether complex, boron trifluoride dioxane complex, boron trifluoride acetic anhydride and boron trifluoride triethylamine complex, perchloric acid, and acetyl perchlorate; the molecular weight regulator comprises at least one of methylal, methoxy methylal, dimethoxy methylal, trimethoxy methylal and formaldehyde di-n-butyl ether; the antioxidant comprises an Irganox catalyst, or comprises an Irganox catalyst and a phosphite auxiliary antioxidant, wherein the Irganox catalyst comprises Irganox1010 and/or Irganox245; the lubricant includes at least one of an amide wax, a PE wax, a PP wax, and an ester wax.

Further, the heat stabilizer includes dicyandiamide and/or melamine.

Further, the copolyoxymethylene resin composition comprises the following raw materials in parts by weight: 90-100 parts of trioxymethylene, 0.1-1.5 parts of functional monomer, 0.5-3.5 parts of cyclic ether compound, 0.03-0.1 part of catalyst, 0.7-0.8 part of molecular weight regulator, 0.01-1 part of antioxidant, 0.05-0.1 part of heat stabilizer, 0.01-0.5 part of lubricant and 0.01-0.5 part of formaldehyde absorbent.

Further, the molecular weight regulator comprises methylal and/or trimethoxy methylal; the catalyst comprises at least one of boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxane complex, boron trifluoride acetic anhydride and boron trifluoride triethylamine complex; the antioxidant is Irganox245; the lubricant is pentaerythritol tetrastearate; the formaldehyde absorbent is adipic dihydrazide; the cyclic ether compound includes ethylene oxide and/or 1, 3-dioxolane.

Further, the raw material of the metal powder comprises at least one of metal simple substances and metal alloys of aluminum, magnesium, barium, calcium, cobalt, zinc, copper, nickel, iron, silicon, titanium, tungsten and zirconium; the ceramic powder is composed of Al as a raw material ₂ O ₃ And/or ZrO ₂ (ii) a The grain size of the main material powder is less than 20 mu m;

the skeleton adhesive comprises at least one of polyethylene, polypropylene, polystyrene, ethylene acrylic acid copolymer and polymethyl methacrylate; the compatibilizing agent comprises maleic anhydride and/or stearic acid.

In conclusion, the invention provides a technical scheme for introducing the hydrocarbon side group into the main chain of the polyformaldehyde, and the melt index of the formaldehyde resin is controlled to be 100-220g/min. The polyformaldehyde resin with the characteristics can obviously improve the compatibility effect with a skeleton adhesive thereof, and improve the feeding uniformity and the acidolysis rate. In addition, in order to maximally not introduce foreign impurities into metal or ceramic products and ensure the performance of the products, inorganic substances, metal oxides, metal hydroxides, metal salts and the like are not selected as additives such as stability and the like for the polyformaldehyde resin. Meanwhile, the polyformaldehyde resin disclosed by the invention adopts dicyandiamide, melamine and the like as heat stabilizers, so that the acidolysis rate of the polyformaldehyde resin can be further obviously improved.

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

(1) According to the technical scheme, the cyclic ether compound with the long alkyl side chain is added to serve as a functional monomer, and then the hydrocarbon side group is introduced to the polyformaldehyde main chain, so that the flowability of polyformaldehyde resin is improved, and the feeding uniformity during preparation of the metal/ceramic resin composition is improved. In addition, the addition of the functional monomer also improves the acidolysis rate of the polyformaldehyde resin to a certain extent, and improves the performance of the metal/ceramic resin composition product. The reason for the analysis by the inventors is that: the hydrocarbon side group is introduced into the polyformaldehyde resin, so that the compatibility with the skeleton binder hydrocarbon resin can be obviously improved, the uniformity of the feeding is further obviously improved, the polyformaldehyde resin and the like are more uniformly distributed in the feeding, and the dispersion uniformity of the metal or inorganic powder is also greatly improved; when the polyformaldehyde resin is subjected to acidolysis, more uniform gap distribution is generated, the contact area of the acid gas and the internal polyformaldehyde resin is increased, and the acidolysis rate is increased; the hydrocarbon side group also provides the effect of an internal lubricant of the polyformaldehyde resin, improves the fluidity of the polyformaldehyde resin, and further improves the fluidity of the metal feed under the same feed preparation process condition.

Therefore, the functional monomer used in the scheme has multiple functions: improve the metal powder dispersion degree of a metal/ceramic resin composition using a polyoxymethylene resin as a binder, improve the flowability of the polyoxymethylene resin, and improve the acid hydrolysis rate of the polyoxymethylene resin.

(2) By adding a proper amount of molecular weight regulator, the polyoxymethylene resin with the melt index of 100-220g/min is obtained, and the feeding uniformity is further improved.

(3) The use of heat stabilizers such as dicyandiamide and melamine improves the acidolysis rate of the polyformaldehyde resin. And inorganic substances, metal oxides, metal hydroxides, metal salts and the like are not selected as additives such as stability and the like, so that impurities are prevented from being introduced into the metal/ceramic resin composition, and the product performance is improved.

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. Unless otherwise specified, the technical means used in the following examples and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents and the like used therein are commercially available.

Examples

1. Polyoxymethylene resin composition

(1) The polyoxymethylene resin composition of the present technical solution comprises the following raw materials:

the raw materials comprise monomers, functional monomers, cyclic ether compounds, catalysts, molecular weight regulators, antioxidants, heat stabilizers and lubricants.

The monomer is trioxymethylene, and the mass portion is 70-100, preferably 90-100.

The cyclic ether compound is 0.01 to 5 parts by mass, preferably 0.5 to 3.5 parts by mass. The following specific cyclic ether compounds may be used: at least one of ethylene oxide, propylene oxide, butylene oxide, 3-chloro-1, 2-propylene oxide, 3-bromo-1, 2-propylene oxide, styrene oxide, oxetane, 3-bis (chloromethyl) oxetane, tetrahydrofuran, 1, 3-dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1, 4-butanediol formal, 1, 5-pentanediol formal, and 1, 6-hexanediol formal. At least one of common ethylene oxide, 1, 3-dioxolane, diethylene glycol formal and 1, 4-cis-butanediol formal is preferable. Most preferred are ethylene oxide and/or 1, 3-dioxolane.

The functional monomer is a cyclic ether compound with a long alkyl side chain, and the mass portion of the cyclic ether compound is 0.01-5 parts, preferably 0.1-1.5 parts. Specific cyclic ether compounds with long hydrocarbyl side chains may be used as follows: 1, 2-epoxyhexane, 1, 2-epoxydecane, 1, 2-epoxydodecane, 1, 2-epoxyoctadecane, 1, 2-epoxyeicosane; 4-pentyl-1, 3-dioxolane, 4-hexyl-1, 3-dioxolane, 4-decyl-1, 3-dioxolane, 4-dodecyl-1, 3-dioxolane, 4-octadecyl-1, 3-dioxolane, 4-eicosyl-1, 3-dioxolane. Preferably 1, 2-epoxydodecane, 1, 2-epoxyoctadecane, 1, 2-epoxyeicosane; 4-dodecyl-1, 3-dioxy pentacyclic, 4-octadecyl-1, 3-dioxy pentacyclic and 4-eicosyl-1, 3-dioxy pentacyclic.

The catalyst can be selected from cationic polymerization catalysts, and the following specific cationic polymerization catalysts can be used: at least one of lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, antimony pentafluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate complex, boron trifluoride dioxane complex, boron trifluoride acetic anhydride and boron trifluoride triethylamine complex, perchloric acid and acetyl perchlorate. Among them, boron trifluoride diethyl ether complex, boron trifluoride dibutyl ether complex, boron trifluoride dioxane complex, boron trifluoride acetic anhydride, and boron trifluoride triethylamine complex are particularly preferable, and the mass part thereof is 0.01 to 0.3 parts, preferably 0.03 to 0.1 parts.

The molecular weight regulator adopts acetal compounds, the mass portion is 0.4-0.8 (obtaining 100-220g/min of polyformaldehyde resin; test condition: temperature 190 ℃ and pressure 2.16 kg), the preference is 0.7-0.8 (obtaining 170-220g/min of polyformaldehyde resin; test condition: temperature 190 ℃ and pressure 2.16 kg). The following specific acetal compounds can be used: at least one alkoxy-containing compound selected from methylal, methoxy methylal, dimethoxy methylal, trimethoxy methylal and formaldehyde di-n-butyl ether. Preferably, methylal and/or trimethoxy methylal.

The mass portion of the antioxidant is 0.01-1. The following specific antioxidants may be used: pentaerythritol tetrakis [3-3',5' -di-tert-butyl-4 ' -hydroxyphenyl ] propionate (Irganox 1010) and/or Irganox245; the above-mentioned antioxidant may be used in combination with a phosphite-based secondary antioxidant (for example, 168). Irganox245 is preferred in the technical scheme.

The mass portion of the heat stabilizer is 0.01-0.5 portion, preferably 0.05-0.1 portion. Specific heat stabilizers may be used as follows: dicyandiamide and/or melamine.

The mass portion of the lubricant is 0.01-0.5. The following specific lubricants may be used: amide wax, PE wax, PP wax, and ester wax. Pentaerythritol tetrastearate (PETS) is preferred.

The mass portion of the formaldehyde absorbent is 0.01-0.5. The following specific formaldehyde absorbers can be used: adipic acid dihydrazide. The formaldehyde absorbent is not an essential component of the polyoxymethylene resin composition, and is mainly used for absorbing formaldehyde generated in the reaction process.

(2) Preparation method

Mixing the above materials uniformly in proportion, adding into a polymerization reactor; the cyclic ether compound, the functional monomer, the catalyst, the molecular weight regulator and the like can be added into a polymerization reactor after pre-mixing 2 or 3 or 4 raw materials and then mixing with trioxymethylene.

The process provided by the present invention is not limited to polymerization equipment, a conventional reaction vessel, twin screw machine, etc. may be used. The polymerization temperature is preferably from 65 to 135 ℃. After the polymerization reaction is finished, crushing reaction products discharged from a polymerization device to obtain polyformaldehyde resin powder (the particle size is 0.05mm-1 mm). Adding alkaline compound or its water solution into the powder for deactivating the polymerization catalyst. The basic compound may be ammonia, amines such as triethylamine, tributylamine, triethanolamine and tributanolamine, or salts of alkali metals and alkali metal hydroxides, and other known catalyst deactivators. According to the requirement, the inactivated polyformaldehyde resin powder can be washed by a method known in the prior art, the unreacted monomer is separated and recovered, the powder is dried, and the like. If necessary, the unstable terminals of the polyoxymethylene resin powder may be decomposed and removed by a known method by adding various stabilizers necessary for stabilization treatment, or the unstable terminals may be capped with a stabilizing substance.

And (3) extruding and granulating the obtained polyformaldehyde resin powder (added with the antioxidant, the heat stabilizer, the lubricant and the formaldehyde absorbent) by using a common double-screw extruder at the granulation temperature of 80-240 ℃. The granulating mode can adopt common post-bracing granulating or water ring granulating or underwater granulating. The obtained pellets were dried at 120 ℃ for 6 hours to obtain polyoxymethylene resin pellets.

2. Metal/ceramic resin composition

The metal/ceramic resin composition comprises 70-95% by mass of metal powder (or ceramic powder) and a binder system, wherein the metal powder may be aluminum, magnesium, barium, calcium, cobalt, zinc, copper, nickel, iron, silicon, titanium, tungsten, zirconium, and metal compounds and metal alloys based on these metals. Not only the alloys that have been produced, but also mixtures of the individual alloy components can be used. The ceramic powder can be oxide such as zinc oxide, aluminum oxide, zirconium oxide, etc.; hydroxides such as hydroxyapatite; carbides such as silicon carbide; nitrides such as silicon nitride and boron nitride; halides such as fluorite; silicates such as steatite; titanates such as barium titanate and lead zirconate titanate; a carbonate salt; a phosphate salt; a ferrite; high temperature superconductors, and the like. Also, cermet resin compositions including ceramic powders, metal powders, and binder systems may be prepared. The ceramic resin composition comprises ceramic powder and binder system, wherein the ceramic powder can be oxides such as zinc oxide, aluminum oxide, zirconium oxide, etc.; hydroxides such as hydroxyapatite; carbides such as silicon carbide; nitrides such as silicon nitride and boron nitride; halides such as fluorite; silicates such as steatite; titanates such as barium titanate and lead zirconate titanate; a carbonate salt; a phosphate salt; a ferrite; high temperature superconductors, and the like. Cermet resin compositions may also be prepared, including ceramic powders, metal powders, and binder systems. These inorganic substances may be used singly or in combination. Various metals, metal alloys, ceramics, and the like.

The metal powder is particularly preferably made of a metal and/or a metal alloy, and the following specific materials can be used: titanium alloy, SUS316L. The ceramic powder may be Al ₂ O ₃ 、ZrO ₂ . The particle size of these powders is preferably 1 to 20 μm.

The adhesive system comprises polyformaldehyde resin (polyformaldehyde resin granules), a skeleton adhesive, a compatilizer and the like. Wherein, the polyformaldehyde resin accounts for 80-90% of the total mass of the adhesive,

the backbone binder may be at least one of polyethylene, polypropylene, polystyrene, ethylene acrylic acid copolymer, and Polymethylmethacrylate (PMMA). In the subsequent examples, polypropylene with a melt index of 30g/10min (the test conditions are that the temperature is 190 ℃ and the pressure is 2.16 kg) is selected as a framework adhesive to carry out the evaluation of the examples, and the framework adhesive accounts for 9-20% of the total mass of the adhesive system.

The compatilizer can be maleic anhydride and/or stearic acid, the evaluation of the embodiment is carried out by selecting the stearic acid, and the compatilizer accounts for 0.5-1.5% of the total mass of the adhesive.

Adding metal powder and/or ceramic powder into an internal mixer, adding polyformaldehyde resin granules, a skeleton binding agent and a compatilizer, and mixing to obtain the metal/ceramic resin composition.

3. Detailed description of the preferred embodiments

(1) Examples 1 to 10 polyoxymethylene resin pellets were prepared by the following method:

adding 100 parts of trioxymethylene (monomer), 1, 3-dioxolane (cyclic ether compound), functional monomer, boron trifluoride diethyl etherate complex catalyst, methylal (molecular weight regulator) and the like according to the adding amount shown in Table 1, adding the materials into a double-screw kneader with the screw diameter of 133mm by adopting a common metering system, and carrying out polymerization reaction by adopting the conventional means in the prior art, wherein the temperature range (polymerization temperature) from a feeding port of the double-screw kneader to each section of a machine head is 65-95 ℃ (optional range of 65-135 ℃), thus obtaining a polymerization product. Grinding the obtained polymerization product into powder using a hammer mill or a pin mill to obtain powder having a particle size of 0.05mm to 1 mm; the prepared powder material and alkaline solution are uniformly mixed (specifically ammonia water) to inactivate the catalyst, and the reaction is carried out in a common horizontal screw conveyor. The obtained deactivated powder was sent to a plate dryer and dried at 120 ℃ for 50min under nitrogen atmosphere.

Uniformly mixing the dried polymerization powder with 0.8 part of antioxidant 245 (Irganox 245), 0.09 part of melamine, 0.2 part of PE wax (pentaerythritol tetrastearate, PETS) and 0.2 part of adipic dihydrazide, extruding and granulating to obtain polyformaldehyde resin granules, specifically extruding and granulating by using a double-screw extruder through the conventional means in the prior art, wherein the range from a feed port of the double-screw extruder to each section of a machine head (the extrusion and granulation temperature is between 150 and 200 ℃ (the optional range is between 80 and 240 ℃).

Table 1: examples 1-10 formulation compositions

(2) Pellets of polyoxymethylene resins of example 11 to example 15 were prepared by the following method:

the polyoxymethylene resin powders obtained in example 10 were weighed and mixed uniformly as shown in table 2, and then subjected to extrusion granulation to obtain polyoxymethylene resin pellets, which were prepared by the same process as in example 10.

Table 2: examples 11-15 formulation compositions

(3) Pellets of polyoxymethylene resins of examples 16 to 20 were prepared by the following method:

polyoxymethylene resin powders obtained in example 1, example 2, example 3, example 4 and example 8 were weighed and mixed in the amounts shown in Table 3, and then subjected to extrusion pelletization, and pellets of polyoxymethylene resins corresponding to examples 16 to 20 were obtained in accordance with the method shown in example 1. In the examples herein, a polypropylene resin (30 g/10min, 190 ℃ C., 2.16kg pressure) was added, which was not a constituent of the polyoxymethylene resin composition of the present embodiment, in order to simulate the composition of the material for preparing the metal resin composition. The use of a polypropylene skeleton binder was required in the preparation of the metal resin composition, and these examples were conducted in order to test the acid hydrolysis performance of the polyoxymethylene resin with the addition of the skeleton binder.

Table 3: examples 16-20 formulation compositions

(4) Preparation of Metal/ceramic resin compositions of examples 21 to 30

The temperature of the Haake internal mixer was raised to 180 ℃ and 128.47g of stainless steel powder, 17-4PH (D90: 15 μm), 12.79g of the polyoxymethylene resin pellets obtained in examples 1 to 10, 1.26g of polypropylene resin melt index of 30g/10min and 0.4g of stearic acid were heated in the Haake internal mixer at 60rpm/min and kneaded for 30min to prepare a dough-like solid matter of examples 21 to 30, that is, a metal/ceramic resin composition.

Experimental example 1: evaluation of Properties of polyoxymethylene resin pellets

(1) Examples 1-10 polyoxymethylene resin pellets were evaluated for odor during compounding using high temperature surface formaldehyde. The high temperature formaldehyde emission test comprises the following steps:

100g of polyoxymethylene particles are placed in an environment at 150 ℃, formaldehyde gas released from the polyoxymethylene resin particles is carried out at a nitrogen flow rate of 170mL/min, and is absorbed by desalted water for 60min, and the amount of formaldehyde absorbed in water is measured in units of μ g/100g by using a spectrophotometer.

(2) The flowability of the polyoxymethylene resin pellets obtained in examples 1 to 10 was evaluated by melt index. The larger the melt index, the better the fluidity. The melt index (MFI) test is roughly as follows:

referring to the national standard GB3682-2000, a melt index instrument is adopted, and the set parameters are as follows: the temperature is 190 ℃, the pressure is 2.16kg, MFI for short, and the unit is g/10min.

(3) To demonstrate that the polyoxymethylene resin pellets prepared in examples 1 to 10 did not introduce impurities into the metal feed process, the smaller the residual amount, expressed as ash residue, the less impurities were introduced into the metal feed. The ash residue test of the polyoxymethylene resin roughly comprises the following steps:

adopting a thermogravimetric analyzer with the model number of TA-Q500; and (3) testing conditions are as follows: under the condition of nitrogen, the temperature rise rate is 5 ℃/min, the temperature is raised to 500 ℃, and the weight retention rate at 495 ℃ is measured.

(4) Tensile breaking strength (MPa), tensile elastic modulus (MPa) and elongation at break, and is tested by a universal tensile testing machine according to national standard GB 1040.2-2006.

The results of the experiments are shown in tables 4 and 5.

Table 4: evaluation results of melt index, weight holding ratio and Formaldehyde Release ratio of polyoxymethylene resin pellets obtained in examples 1 to 10

Table 5: evaluation results of mechanical Properties of polyoxymethylene resin pellets obtained in examples

	MFI(g/10min)	Tensile breaking strength MPa	Tensile modulus of elasticity MPa	Elongation at break%
					Example 1	120	61	2700	15％
Example 2	122	62	2850	16％
					Example 6	161	62	2900	10％
Example 8	175	43	1700	25％
					Example 9	210	63	2950	5％
Example 10	213	63	3000	6％

As can be seen from the data in Table 4, the amount of methylal used was kept in the range of 0.4 to 0.8 parts, and the MFI value was maintained in the range of 100 to 220 g/min; the amount of methylal is kept within the range of 0.7-0.8 parts, and the MFI value can be maintained within the range of 200-220 g/min. The melt index of the polyformaldehyde resin granules is maintained in the range of 100-220g/min, which is beneficial to increasing the fluidity, and the feeding uniformity and the smoothness degree of the process can be increased when the metal/ceramic resin composition is prepared subsequently. Referring to the data in Table 5, the polyoxymethylene resin pellets still maintained desirable and desirable mechanical properties at higher melt indices (examples 1,2, 6, 9, 10).

When methylal is used for regulating and controlling the melt index, a proper amount of functional monomer is added, so that the fluidity (melt index) of the resin can be improved to a certain extent. The addition of the functional monomer can be seen to increase the fluidity of the resin when examples 2 to 4 are compared with example 1, examples 6 to 8 are compared with example 5, and example 10 is compared with example 9. The addition of a proper amount of functional monomer can improve the melt index without having a significant effect on the mechanical properties of the resin, such as example 1 and example 2, example 9 and example 10. However, the addition of the functional monomer excessively improves the flowability of the resin, but greatly reduces the mechanical properties of the resin, as shown in examples 6 and 8 in tables 4 and 5. Therefore, the amount of the functional monomer to be added is preferably controlled within a range of 0.01 to 5 parts, more preferably 0.1 to 1.5 parts.

In addition, all the polyformaldehyde resin granules prepared by the scheme have no ash residue, and the formaldehyde emission is low.

Experimental example 2: evaluation of acid hydrolysis Rate of polyoxymethylene resin pellets

Pellets of example 11 to example 15 and example 16 to example 20 were injection-molded into a bar having a length of 100mm, a width of 10mm and a height of 4mm, and a piece having a length of about 1 to 1.5cm was cut at the end of the bar, and the piece was weighed and used for testing. Putting a test sample section to be tested into a test tube, transferring 5ml of 68% concentrated nitric acid into the test tube, starting timing, quickly taking out the test sample section in the test tube and washing the test sample section clean at 5min, wiping off water on the test sample section, weighing the mass of the residual test sample section, and dividing the mass reduction value by the original mass to obtain the acidolysis mass percentage%. The larger the mass percentage for acid hydrolysis, the faster the acid hydrolysis rate of the polyoxymethylene resin. See tables 6 and 7 for experimental results.

Table 6: example 11 acid hydrolysis Rate of example 15

It can be seen from the experimental data of table 6 that dicyandiamide and melamine can significantly improve the acid hydrolysis of polyoxymethylene (comparative example 11 with examples 12 and 13). Calcium stearate (example 14), although also a common thermal stabilizer, does not significantly increase the rate of acid hydrolysis as does dicyandiamide and melamine. In addition, the addition of calcium stearate can introduce metal oxide impurities. Example 15 the lubricant PE wax (pentaerythritol tetrastearate) was added on the basis of example 13, and the acid hydrolysis rate of polyoxymethylene was not affected.

Table 7: example 16-acid hydrolysis Rate of example 20

From the experimental data in table 7, it is understood that the acid hydrolysis rate of the polyoxymethylene resins (example 17 to example 19 and example 16) to which the cyclic ether compound having a long hydrocarbon-based side chain is added is greatly improved. On the other hand, increasing the amount of cyclic ether compound with a long hydrocarbon side chain and increasing the amount of methylal did not increase the rate of acidolysis of the resin very effectively, so the cyclic ether compound with a long hydrocarbon side chain was maintained within a certain range (compare example 20 with examples 17 to 19). Therefore, the addition of the cyclic ether compound with a long hydrocarbyl side chain can improve the resin fluidity and the resin acidolysis rate, and obtain unexpected technical effects.

Experimental example 3: evaluation of dispersibility of Metal powder

The solid materials obtained in examples 21 to 30 were cut out at 8 places with an arbitrary selection of portions, and 7g of each portion was cut out. Next, the metal/ceramic resin composition was degreased in a muffle furnace set at 550 ℃, and the weight of the remaining metal was measured. Then, the ratio of the maximum weight to the minimum weight is determined. The smaller the ratio, the better the dispersibility. The dispersibility of the metal powder is preferably 1.15 or less, more preferably 1.10 or less, and still more preferably 1.05 or less. See table 8 for experimental results.

Table 8: stainless Steel powder dispersibility stainless Steel powder polyoxymethylene resin Polypropylene stearic acid Metal powder dispersibility of examples 21-30

Example 21 in comparison with examples 22 to 24, no functional monomer was added, the dispersibility of the metal powder was not satisfactory, and the difference between the maximum weight and the minimum weight of the metal in the obtained sample was 16%. While examples 22-24 show a 7-9% difference between the maximum and minimum weight after addition of certain functional monomers. Example 25 compared to examples 26 and 27, no functional monomer was added, the dispersibility of the metal powder was not satisfactory, and the difference between the maximum weight and the minimum weight of the metal in the obtained sample was 12%. While examples 22-24 show a difference of 6-10% between the maximum weight and the minimum weight after addition of a certain functional monomer. Example 29 compared to example 30, the dispersibility of the metal powder was not satisfactory without adding the functional monomer, and the difference between the maximum weight and the minimum weight of the metal in the obtained sample was 5%. In example 30, the difference between the maximum weight and the minimum weight is 1% after a certain amount of functional monomer is added. The above experimental data show that the functional monomer can increase the dispersion property of the metal powder in the metal/ceramic resin composition, and improve the product quality. However, the above effects were not achieved by simply adding the functional monomer, but the dispersibility of the metal powder was inferior to 1.20 in example 28, which is inferior to example 25 in which the functional monomer was not added, because the amount of the functional monomer added was too large. This indicates that the amount of the functional monomer should be maintained within a certain range to ensure the effect of promoting the dispersion of the metal powder. The inventors further analyzed the cause of the above phenomenon, and probably: the side chain of the functional monomer can improve the compatibility between resins, thereby improving the uniformity of material distribution. However, the introduction of an excessive amount of functional monomer may disrupt the original balance of the system, resulting in poor dispersibility of the metal powder.

Therefore, a cyclic ether compound having a long hydrocarbon side chain is added as a functional monomer to a polyoxymethylene resin, and has a triple function: improve the metal powder dispersion degree of a metal/ceramic resin composition using a polyoxymethylene resin as a binder, improve the flowability of the polyoxymethylene resin, and improve the acid hydrolysis rate of the polyoxymethylene resin.

In addition, in examples 21, 25 and 29, as the amount of methylal added increases, the dispersibility of the metal powder becomes better, so that the use of the molecular weight modifier improves the resin fluidity and also improves the product quality.

The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be defined by the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims (10)

1. The copolyformaldehyde resin composition is characterized by comprising the following raw materials in parts by weight: 70-100 parts of trioxymethylene, 0.01-5 parts of functional monomer, 0.01-5 parts of cyclic ether compound, 0.01-0.3 part of catalyst, 0.4-0.8 part of molecular weight regulator, 0.01-1 part of antioxidant, 0.01-0.5 part of heat stabilizer and 0.01-0.5 part of lubricant;

the functional monomer is a cyclic ether compound with a long alkyl side chain.

2. The copolyoxymethylene resin composition as claimed in claim 1, wherein the cyclic ether compound comprises at least one of ethylene oxide, propylene oxide, butylene oxide, 3-chloro-1, 2-propylene oxide, 3-bromo-1, 2-propylene oxide, styrene oxide, oxetane, 3-bis (chloromethyl) oxetane, tetrahydrofuran, 1, 3-dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1, 4-butanediol formal, 1, 5-pentanediol formal, and 1, 6-hexanediol formal.

3. The copolyoxymethylene resin composition as claimed in claim 2, wherein the functional monomer comprises 1, 2-epoxyhexane, 1, 2-epoxydecane, 1, 2-epoxydodecane, 1, 2-epoxyoctadecane, 1, 2-epoxyeicosane; 4-pentyl-1, 3-dioxolane, 4-hexyl-1, 3-dioxolane, 4-decyl-1, 3-dioxolane, 4-dodecyl-1, 3-dioxolane, 4-octadecyl-1, 3-dioxolane, 4-eicosyl-1, 3-dioxolane. Preferably 1, 2-epoxydodecane, 1, 2-epoxyoctadecane, 1, 2-epoxyeicosane; 4-dodecyl-1, 3-dioxy pentacyclic, 4-octadecyl-1, 3-dioxy pentacyclic and 4-eicosyl-1, 3-dioxy pentacyclic.

4. A copolyoxyformaldehyde resin composition comprising the compound according to claim 3, wherein the catalyst comprises at least one of lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, antimony pentafluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxane complex, boron trifluoride acetic anhydride and boron trifluoride triethylamine complex, perchloric acid and acetyl perchlorate; the molecular weight regulator comprises at least one of methylal, methoxy methylal, dimethoxy methylal, trimethoxy methylal and formaldehyde di-n-butyl ether; the antioxidant comprises an Irganox catalyst, or comprises an Irganox catalyst and a phosphite auxiliary antioxidant, wherein the Irganox catalyst comprises Irganox1010 and/or Irganox245; the lubricant includes at least one of an amide wax, a PE wax, a PP wax, and an ester wax.

5. A copolyformaldehyde resin composition as claimed in claim 4, wherein the heat stabilizer comprises dicyandiamide and/or melamine.

6. The copolyformaldehyde resin composition as claimed in claim 5, wherein the raw materials comprise, in parts by weight: 90-100 parts of trioxymethylene, 0.1-1.5 parts of functional monomer, 0.5-3.5 parts of cyclic ether compound, 0.03-0.1 part of catalyst, 0.7-0.8 part of molecular weight regulator, 0.01-1 part of antioxidant, 0.05-0.1 part of heat stabilizer, 0.01-0.5 part of lubricant and 0.01-0.5 part of formaldehyde absorbent.

7. A copolyformaldehyde resin composition as claimed in claim 6, wherein the molecular weight regulator comprises methylal and/or trimethoxy methylal; the catalyst comprises at least one of boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxane complex, boron trifluoride acetic anhydride and boron trifluoride triethylamine complex; the antioxidant is Irganox245; the lubricant is pentaerythritol tetrastearate; the formaldehyde absorbent is adipic dihydrazide; the cyclic ether compounds include ethylene oxide and/or 1, 3-dioxolane.

8. The process for producing a copolyoxyformaldehyde resin composition as claimed in any one of claims 1 to 7, which comprises the steps carried out in the following order:

s1: mixing a monomer, a functional monomer, a cyclic ether compound, a catalyst and a molecular weight regulator, and carrying out polymerization reaction to obtain a reaction product; crushing, deactivating, washing and drying the reaction product to obtain polyformaldehyde resin powder;

s2: mixing polyformaldehyde resin powder, an antioxidant, a heat stabilizer and a lubricant, performing extrusion granulation, and performing granulation and drying to obtain polyformaldehyde resin granules; the melt index of the polyformaldehyde resin pellets is 100-220g/min.

9. The metal/ceramic resin composition prepared by using the copolyformaldehyde resin composition as claimed in any one of claims 1 to 7, wherein the raw materials comprise, in parts by weight, 70 to 95% of a main material powder and 5 to 30% of a binder system;

the main material powder comprises metal powder and/or ceramic powder; the raw material of the metal powder comprises at least one of simple metal, metal compound and metal alloy of aluminum, magnesium, barium, calcium, cobalt, zinc, copper, nickel, iron, silicon, titanium, tungsten and zirconium; the raw material of the ceramic powder includes at least one of an oxide, a hydroxide, a carbide, a nitride, a halide, a titanate, a carbonate, a phosphate, and a high-temperature superconductor;

the adhesive system comprises the following components in a mass ratio of 80-90:9-20:0.5-1.5 of polyformaldehyde resin granules, a skeleton binding agent and a compatilizer.

10. The method for preparing metal/ceramic resin composition according to claim 9, characterized in thatCharacterized in that the raw material of the metal powder comprises at least one of simple metal substances and metal alloys of aluminum, magnesium, barium, calcium, cobalt, zinc, copper, nickel, iron, silicon, titanium, tungsten and zirconium; the ceramic powder is composed of Al as a raw material ₂ O ₃ And/or ZrO ₂ (ii) a The grain size of the main material powder is less than 20 mu m;

the skeleton adhesive comprises at least one of polyethylene, polypropylene, polystyrene, ethylene acrylic acid copolymer and polymethyl methacrylate; the compatibilizing agent comprises maleic anhydride and/or stearic acid.