Epoxy anhydride encapsulating composition and preparation method thereof
阅读说明：本技术 一种环氧酸酐灌封组合物及其制备方法 (Epoxy anhydride encapsulating composition and preparation method thereof ) 是由 郑敏敏 孙岳 杨李懿 刘攀登 甘艳霞 于 2020-07-16 设计创作，主要内容包括：本发明公开了一种环氧酸酐灌封组合物及其制备方法。一种环氧酸酐灌封组合物,20～50份的环氧树脂、15～45份的酸酐类固化剂、5～30份具有支化结构的增韧剂、0.01～0.3份的固化促进剂、0～150份的填料。本发明的产品该组合物可用于环氧浇注绝缘材料,其具有收缩率较低,耐热性较好,耐冷热冲击性能较好优点。(The invention discloses an epoxy anhydride potting composition and a preparation method thereof. An epoxy anhydride potting composition comprises 20-50 parts of epoxy resin, 15-45 parts of anhydride curing agent, 5-30 parts of toughening agent with a branched structure, 0.01-0.3 part of curing accelerator and 0-150 parts of filler. The product of the invention can be used for epoxy casting insulating materials, and has the advantages of low shrinkage, good heat resistance and good cold and heat shock resistance.)
1. An epoxy anhydride potting composition, which is characterized in that: the feed is prepared from the following raw materials in parts by weight: 20-50 parts of epoxy resin, 15-45 parts of anhydride curing agent, 5-30 parts of toughening agent with a branched structure, 0.01-0.3 part of curing accelerator and 0-150 parts of filler; the molecular structural formula of the toughening agent with the branched structure is as follows:
wherein 5. gtoreq.n1≥1，5≥n2≥1，5≥n3≥1，R1Is- (COC)6H4COOCH2CH2O)m1H，R2Is- (COC)6H4COOCH2CH2O)m2H，R3Is- (COC6H4COOCH2CH2O) m3H; wherein m1 is more than or equal to 1, m2 is more than or equal to 1, and m3 is more than or equal to 1.
2. The epoxy anhydride potting composition of claim 1, wherein: the composite material is prepared from the following raw materials in parts by weight: 30-50 parts of epoxy resin, 20-35 parts of anhydride curing agent, 5-30 parts of toughening agent with a branched structure, 0.01-0.15 part of curing accelerator and 20-100 parts of filler.
3. The epoxy anhydride potting composition of claim 1, wherein: the toughening agent with a branched structure is polyester formed by reacting phthalic anhydride and alcohols.
4. The epoxy anhydride potting composition of claim 1, wherein: the alcohols are diols and triols.
5. The epoxy anhydride potting composition of claim 1, wherein: the epoxy value of the epoxy resin is 0.400eq/100 g-0.800 eq/100 g.
6. The epoxy anhydride potting composition of claim 1, wherein: the anhydride curing agent is selected from one or more of aromatic acid anhydride, aliphatic acid anhydride and alicyclic acid anhydride.
7. The epoxy anhydride potting composition of claim 1, wherein: the curing accelerator is selected from one or more of benzyl dimethylamine, 2,4, 6-tri (dimethylaminomethyl) phenol, N-dimethylaniline, diethylaminopropylamine, 2-ethyl-4-methylimidazole, acetylacetone complex, zinc acetylacetonate, benzyl trimethyl ammonium chloride, triethanolamine borate, triethanolamine titanate, triphenylphosphine and salts thereof, 1, 8-diaza-bicyclo (5,4,0) -7-undecene and organic salts thereof and 2-phenylimidazoline.
8. The epoxy anhydride potting composition of claim 1, wherein: the filler is selected from one or more of silicon powder, aluminum oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, boron nitride and aluminum nitride; the filler has an average particle diameter of 1 to 50 μm.
9. The method for preparing an epoxy anhydride potting composition according to any of claims 1 to 8, wherein: the method comprises the following steps:
step 1: preparing a first component, and stirring and mixing 20-50 parts by weight of epoxy resin, 5-30 parts by weight of a toughening agent with a branched structure and 50-150 parts by weight of a filler at the temperature of 20-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100 Pa-101.325 kPa for 2-3 hours;
step 2: preparing a second component, and stirring and mixing 25-50 parts by weight of anhydride curing agent and 0.01-0.30 part by weight of curing accelerator for 2-3 hours at the temperature of 20-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100 Pa-101.325 kPa;
and step 3: preparing an epoxy anhydride encapsulating composition, and stirring and mixing the first component prepared in the step 1 and the second component prepared in the step 2 for 1-2 hours at the temperature of 20-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100 Pa-101.325 kPa.
10. The method of claim 9, wherein the method comprises the steps of: the method comprises the following steps:
step 1: preparing a first component, and stirring and mixing 20-50 parts by weight of epoxy resin, 5-30 parts by weight of a toughening agent with a branched structure and 0-150 parts by weight of a filler for 2-3 hours at the temperature of 70-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100-500 Pa;
step 2: preparing a second component, and stirring and mixing 15-45 parts by weight of anhydride curing agent and 0.01-0.30 part by weight of curing accelerator for 2-3 hours at the temperature of 70-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100-500 Pa;
and step 3: preparing an epoxy anhydride encapsulating composition, and stirring and mixing the first component prepared in the step 1 and the second component prepared in the step 2 for 1-2 hours at the temperature of 60-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100-500 Pa.
Technical Field
The invention relates to the field of epoxy casting insulating materials, in particular to an epoxy-anhydride potting composition and a preparation method thereof.
Background
The epoxy potting compound has the advantages of improving the dielectric property, mechanical strength, thermal conductivity, environmental resistance and the like of electrical and electronic equipment, but still has some problems to be solved and improved. Epoxy molecules contain a large number of epoxy groups, and after the epoxy resin is cured, the epoxy resin has high crosslinking density, molecular chains lack sliding, and the internal stress is large, so that the cured substance is brittle and easy to crack. Cracking will degrade product performance, lead to breakdown, flaking, and compromised product life and reliability.
The stress that causes cracking is mainly from two points. On the other hand, the curing of epoxy resins is an exothermic reaction, and stress concentration is caused by uneven distribution of heat generated during curing. On the other hand, metal inserts such as copper, aluminum, iron core, coil, etc. are often embedded in the casting, and since the resin and these metals have different thermal expansion coefficients, the improper design or operation will result in uneven stress distribution.
The existing modification method comprises the following steps: the introduction of the toughening agent is to improve the cracking resistance, wherein the cold and hot shock resistance is an important index for testing the cracking resistance of the product. The epoxy resin toughening agent mainly comprises: rubber elastomers, thermoplastic resins, thermotropic liquid crystal polymers, flexible tougheners, and the like.
Toughening rubber elastomer
The rubber elastomer toughened epoxy resin can reduce internal stress under certain conditions, increase the impact strength of the material, and improve the water resistance, weather resistance and other properties. But the elastic modulus and the glass transition temperature of the system are easy to be reduced, and the toughening effect on epoxy resin and rubber elastomer with high crosslinking density is very small. In recent years, polysiloxane toughened epoxy has also been developed due to the characteristics of low surface energy, good flexibility, good thermal oxidation resistance and the like. However, due to the large difference in solubility parameters, the compatibility is poor and phase separation occurs in the cured precursor system.
(ii) thermoplastic resin
The thermoplastic resin has the characteristics of high toughness, high strength, high heat resistance and the like. However, the thermoplastic resin is difficult to dissolve in common solvents, the requirements on curing and processing conditions are high, and simultaneously, the toughening effect is inferior to that of elastomers due to poor compatibility of two phases of a cured modified epoxy system and weak interfacial force.
③ thermotropic liquid crystal polymer toughening
Thermotropic Liquid Crystal Polymer (TLCP) is a special high-performance thermoplastic polymer, and the molecular structure of the thermotropic liquid crystal polymer contains a large number of rigid mesogenic units (esters, biphenyls, methyl styrenes and the like) and a certain amount of flexible chain segments, so that the thermotropic liquid crystal polymer has good mechanical properties and heat resistance. However, thermotropic liquid crystals are difficult to be uniformly dispersed in an epoxy resin matrix by a general method due to their high melting points, and further application thereof is limited.
Active flexibilizer
The introduction of an active toughening agent is one of the most common toughening modes in the production of epoxy casting insulating materials at present. Some long aliphatic chains (such as polyether polyol) with hydroxyl (-OH) and ether bond (-O-) can play a better role in flexibility enhancement due to larger molecular weight, such as DY040 and FD-400 in foreign markets, and polypropylene glycol (PPG), polyethylene glycol (PEG), polypropylene glycol glycidyl ether (PPGDEG), polyethylene glycol glycidyl ether (PEGDEG) and the like in domestic markets.
The above prior art has the following disadvantages: the introduction of a large number of flexible structures improves the cold and hot shock resistance of the material, but also causes the Tg of the material to be greatly reduced, so that the heat resistance of a cured product is substantially sacrificed, and the problem that the cold and hot shock resistance and the heat resistance cannot be simultaneously achieved exists.
Disclosure of Invention
Aiming at the defects in the prior art, the first purpose of the invention is to provide the epoxy anhydride potting composition, the toughening agent with a branched structure is adopted, the toughness of the prepared potting cured product is improved, the cold and hot impact performance is better, the curing shrinkage rate is reduced, and the heat resistance of the potting cured product is better.
The second purpose of the invention is to provide a preparation method of the epoxy anhydride potting composition, which is easy to realize and can be produced in a large scale.
In order to achieve the first object, the invention provides the following technical scheme: an epoxy anhydride potting composition is prepared from the following raw materials in parts by weight: 20-50 parts of epoxy resin, 15-45 parts of anhydride curing agent, 5-30 parts of toughening agent with a branched structure, 0.01-0.3 part of curing accelerator and 0-160 parts of filler; the molecular structural formula of the toughening agent with the branched structure is as follows:
wherein 5. gtoreq.n1≥1，5≥n2≥1，5≥n3≥1，R1Is- (COC)6H4COOCH2CH2O)m1H，R2Is- (COC)6H4COOCH2CH2O)m2H，R3Is- (COC6H4COOCH2CH2O) m3H; wherein m1 is more than or equal to 1, m2 is more than or equal to 1, and m3 is more than or equal to 1.
By adopting the technical scheme, as the toughening agent molecules used by the invention have the branched structure, when the epoxy resin is cured and releases heat, the toughening agent molecular chains positioned between the epoxy resins can relatively slide, the internal stress is released, and the stress concentration phenomenon is avoided, so that the stress distribution of the whole cured product is uniform, the cold and heat impact resistance is improved, the curing shrinkage rate can be reduced, the size stability of the cured product is ensured, and the pouring process is convenient; meanwhile, the molecules of the toughening agent contain benzene rings with rigid structures, flexible carbon-carbon and carbon-oxygen single bonds and a plurality of branched chains, so that the heat resistance and the toughening of the encapsulated cured material are improved, and the cured material prepared by the method has better heat resistance and cold and heat shock resistance.
The present invention in a preferred example may be further configured to: the composite material is prepared from the following raw materials in parts by weight: 30-50 parts of epoxy resin, 20-35 parts of anhydride curing agent, 5-30 parts of toughening agent with a branched structure, 0.01-0.15 part of curing accelerator and 20-100 parts of filler.
The using amount of the toughening agent is too low, the number of molecular chains of the toughening agent positioned between the epoxy resins is small, and although relative sliding can be carried out to release internal stress and reduce stress concentration to a certain extent, the toughening effect of the number of the molecular chains of the toughening agent is limited. The use level of the toughening agent is too high, the toughening agent molecules positioned between the toughening agent molecules are too high, the slippage between the toughening agent molecular chains can be hindered, the cold and hot impact resistance and the toughness are reduced, the viscosity of matrix resin can be too high due to the promotion, the addition level of the heat-conducting filler is limited, and the dispersion of the heat-conducting filler is not uniform. The cross-linking density of the cured epoxy resin pouring sealant is determined by the using amount of the anhydride curing agent, and the cured epoxy resin pouring sealant becomes hard and brittle, the mechanical property is obviously reduced, and the heat resistance is poor due to the excessive using amount of the anhydride curing agent; if the amount of the anhydride curing agent is too small, the obtained epoxy resin potting cured product has low mechanical strength, poor mechanical property and poor heat resistance. The curing accelerator is less in dosage, so that the obtained epoxy resin pouring sealant can be cured for a long time, and the mechanical property after curing is poor; too much curing accelerator can cause the epoxy resin to be cured too fast, the crosslinking degree of the epoxy resin is higher, and the obtained cured epoxy resin has poor cold and heat shock resistance.
The present invention in a preferred example may be further configured to: the toughening agent with a branched structure is polyester formed by reacting phthalic anhydride and alcohols.
By adopting the technical scheme, the phthalic anhydride contains benzene rings in the molecular structure, and the condensate has good heat resistance, higher thermal deformation temperature and excellent electrical property; the polyester formed by the reaction of phthalic anhydride and alcohol has good heat resistance, higher thermal deformation temperature and excellent electrical property, solves the processing problem of phthalic anhydride, and is in liquid state by utilizing the reaction of alcohol and the polyester, thereby being convenient for processing and mixing.
The present invention in a preferred example may be further configured to: the alcohols are diols and triols.
By adopting the technical scheme, the number of the branched chains of the toughening agent is ensured, so that the cold and heat shock resistance of the cured epoxy resin is ensured; the polyester generated by the reaction of the dihydric alcohol and the trihydric alcohol with phthalic anhydride is liquid and has moderate viscosity, and is further convenient to process and mix to prepare the encapsulating composition.
The present invention in a preferred example may be further configured to: the epoxy value of the epoxy resin is 0.400eq/100 g-0.800 eq/100 g.
By adopting the technical scheme, the epoxy value of the used epoxy resin is moderate, and the heat resistance of the cured encapsulation material after crosslinking and curing is better and can be prevented from being too hard and brittle.
The present invention in a preferred example may be further configured to: the anhydride curing agent is selected from one or more of aromatic acid anhydride, aliphatic acid anhydride and alicyclic acid anhydride.
By adopting the technical scheme, the epoxy resin can be mixed with a toughening agent for use, and the heat resistance of the encapsulation curing material is improved.
The present invention in a preferred example may be further configured to: the curing accelerator is selected from one or more of benzyl dimethylamine, 2,4, 6-tri (dimethylaminomethyl) phenol, N-dimethylaniline, diethylaminopropylamine, 2-ethyl-4-methylimidazole, acetylacetone complex, zinc acetylacetonate, benzyl trimethyl ammonium chloride, triethanolamine borate, triethanolamine titanate, triphenylphosphine and salts thereof, 1, 8-diaza-bicyclo (5,4,0) -7-undecene and organic salts thereof and 2-phenylimidazoline.
By adopting the technical scheme, the curing of the epoxy resin is accelerated, the gel time of the epoxy resin is controlled, and the potting cured material with better mechanical property is obtained.
The present invention in a preferred example may be further configured to: the filler is selected from one or more of silicon powder, aluminum oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, boron nitride and aluminum nitride; the filler has an average particle diameter of 1 to 50 μm.
By adopting the technical scheme, the heat resistance and the mechanical strength of the encapsulated condensate can be improved; the average particle size of the filler is in a nanometer level, and the filler is difficult to disperse uniformly in matrix resin, so that the heat resistance and the cold and heat shock resistance of an epoxy resin potting cured product are reduced; the excessive average particle size of the filler can cause the bubble defect in the epoxy resin potting condensate, and the heat resistance and the cold and heat shock resistance are reduced; the invention selects the filler with the diameter of 1-50 mu m, ensures the dispersibility, reduces the generation of internal defects, and is beneficial to improving the heat resistance and the cold and heat shock resistance.
In order to achieve the second object, the invention provides the following technical scheme: a preparation method of an epoxy anhydride potting composition comprises the following steps: the method comprises the following steps:
step 1: preparing a first component, and stirring and mixing 20-50 parts by weight of epoxy resin, 5-30 parts by weight of a toughening agent with a branched structure and 50-150 parts by weight of a filler at the temperature of 20-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100 Pa-101.325 kPa for 2-3 hours;
step 2: preparing a second component, and stirring and mixing 25-50 parts by weight of anhydride curing agent and 0.01-0.30 part by weight of curing accelerator for 2-3 hours at the temperature of 20-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100 Pa-101.325 kPa;
and step 3: preparing an epoxy anhydride encapsulating composition, and stirring and mixing the first component prepared in the step 1 and the second component prepared in the step 2 for 1-2 hours at the temperature of 20-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100 Pa-101.325 kPa.
By adopting the technical scheme, the method is easy to realize and can be used for large-scale production.
The present invention in a preferred example may be further configured to: the method comprises the following steps:
step 1: preparing a first component, and stirring and mixing 20-50 parts by weight of epoxy resin, 5-30 parts by weight of a toughening agent with a branched structure and 0-150 parts by weight of a filler for 2-3 hours at the temperature of 70-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100-500 Pa;
step 2: preparing a second component, and stirring and mixing 15-45 parts by weight of anhydride curing agent and 0.01-0.30 part by weight of curing accelerator for 2-3 hours at the temperature of 70-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100-500 Pa;
and step 3: preparing an epoxy anhydride encapsulating composition, and stirring and mixing the first component prepared in the step 1 and the second component prepared in the step 2 for 1-2 hours at the temperature of 60-80 ℃, the stirring speed of 500-1500 r/min and the pressure of 100-500 Pa.
By adopting the technical scheme, the composition with good uniformity and high stability can be prepared.
In summary, the invention has the following beneficial technical effects:
1. the toughening agent with a branched structure is adopted in the epoxy anhydride potting composition, so that the toughness of the prepared potting cured product is improved, the cold and hot impact performance is good, the curing shrinkage rate is reduced, and the heat resistance of the potting cured product is good.
2. By the preparation method of the epoxy anhydride potting composition, the composition with good uniformity and high stability can be prepared, is easy to realize, and can be produced in a large scale.
Detailed Description
The present invention will be described in further detail with reference to examples.
Examples of preparation of raw materials and/or intermediates
Preparation example 1: preparation of toughening agent with branched structure: adding ethylene glycol, glycerol and phthalic anhydride into a three-neck flask provided with a heating jacket, a stirrer, a thermometer and a condenser, heating to 90 ℃, and stirring for 20min to fully mix; and then heating to 200 ℃ at the speed of 2 ℃/min, keeping the temperature at 200 ℃ until no water molecules are distilled off, and stopping the reaction to obtain light yellow transparent liquid, namely the toughening agent A.
Preparation example 2: preparation of toughening agent with branched structure: adding ethylene glycol, 1,2, 4-butanetriol and phthalic anhydride into a three-neck flask provided with a heating jacket, a stirrer, a thermometer and a condenser, heating to 90 ℃, and stirring for 20min to fully mix; and then heating to 200 ℃ at the speed of 2 ℃/min, keeping the temperature at 200 ℃ until no water molecules are distilled off, and stopping the reaction to obtain light yellow transparent liquid, namely the toughening agent B.
Preparation example 3: preparation of toughening agent with branched structure: adding ethylene glycol, 1,2, 5-pentanetriol and phthalic anhydride into a three-neck flask provided with a heating jacket, a stirrer, a thermometer and a condenser, heating to 90 ℃, and stirring for 20min to fully mix the materials; and then heating to 200 ℃ at the speed of 2 ℃/min, keeping the temperature at 200 ℃ until no water molecules are distilled off, and stopping the reaction to obtain light yellow transparent liquid, namely the toughening agent C.