Low-chroma transparent epoxy vinyl ester resin as well as preparation method and application thereof

Abstract

The invention discloses low-chroma transparent epoxy vinyl ester resin as well as a preparation method and application thereof. By optimizing the preparation process and selecting the compound catalyst, the reaction temperature of the synthesis process is reduced, and the temperature in the preparation process is not higher than 90 DEG C all the time, so that the reaction process is easier to control, and the product is low in chroma and good in transparency. The prepared epoxy vinyl ester resin has excellent transparency and chromaticity, the mechanical property of a casting body is outstanding, and the epoxy vinyl ester resin has good toughness and heat resistance and is excellent matrix resin for environment-friendly photocureable coatings.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and particularly relates to a low-haze transparent epoxy vinyl ester resin as well as a preparation method and application thereof. BACKGROUND

[0002] Epoxy vinyl ester resin (also known as vinyl ester resin VE or epoxy acrylic resin) is a kind of thermosetting high polymer material, which is prepared by heating reaction of unsaturated acid and epoxy resin as main raw materials under the action of catalyst and other additives, and the molecular end group or side group thereof contains unsaturated double bond. As one of the resin varieties with larger amount in composite materials, epoxy vinyl ester resin is usually synthesized by reaction of bisphenol type or phenolic type epoxy resin and methacrylic acid, and has excellent mechanical properties and corrosion resistance of epoxy resin, and outstanding curing property and molding processability of unsaturated polyester resin, can be dissolved in styrene and acrylic monomer, and has wide application fields covering anti-corrosion coating, chemical equipment lining, electronic packaging, glass steel products and other industries, and continues to expand.

[0003] However, with the improvement of comprehensive performance requirements of resin in high-end application scenarios (such as LED packaging, transparent composite materials and environmentally friendly photocuring coating), the existing epoxy vinyl ester resin gradually exposes many shortcomings, which are embodied in the following aspects:

[0004] (1) The synthesis process generally depends on high temperature, and the side reactions occur frequently and are difficult to control. The synthesis process of the existing epoxy vinyl ester resin generally adopts a high-temperature reaction system, and the conventional reaction temperature is generally higher than 100℃, which makes it difficult to accurately control the reaction process. For example, the preparation method of the mechanical property enhanced epoxy vinyl ester resin disclosed in Chinese patent CN116143997A needs to carry out chain extension reaction at 100-150℃, and then carry out subsequent heat preservation reaction at 100-120℃, and the whole process at high temperature easily causes local reaction to be violent; the synthesis process of the high-temperature resistant vinyl ester resin disclosed in Chinese patent CN117903415A needs to heat the epoxy resin and acrylic monomer at 100-120℃ for 1-3h, and also has the process risk caused by high temperature. The synthesis process of the low styrene content resin disclosed in Chinese patent CN1935870A has a ring-opening esterification reaction temperature as high as 120-160℃. The high-temperature environment not only accelerates the decomposition of organic peroxide and initiates the side reactions such as double bond self-polymerization, but also causes the oxidation and dehydrogenation of resin molecular chain, which directly causes the problems such as deepening of product color and decline of transparency.

[0005] (2) The optical performance is insufficient, and it is difficult to adapt to the demand of high-end transparent application. The colority of the existing epoxy resin is generally between 20-50Hazen, and the transparency is lower than 90%, which cannot meet the requirements of LED packaging, transparent composite materials, high-end photocuring coating and other scenes with high optical purity requirements, and seriously limits the application expansion of the epoxy resin in high-end fields.

[0006] (3) There is an inherent contradiction in mechanical properties, and it is difficult to balance strength and toughness. There is a difficult balance problem between the strength, toughness and heat resistance of the existing resin: the molecular structure of the traditional unmodified resin lacks flexible groups, the impact strength of the cast body is low, and the brittleness is obvious; Chinese patent CN100358931C introduces carboxyl-terminated liquid nitrile rubber and other flexible components into epoxy vinyl ester resin, which can increase the impact strength to 20-30 KJ / m², but it is easy to cause poor mutual solubility of the resin and crosslinking monomer, phase separation or delamination phenomenon, affecting the stability of the product, and cannot meet the requirements of complex working conditions on comprehensive mechanical properties.

[0007] Therefore, it is urgent to develop a low-color transparent epoxy vinyl ester resin with mild and controllable synthesis process, excellent optical performance and good mechanical balance. SUMMARY

[0008] In order to overcome the deficiencies existing in the prior art, aiming at the problems of high reaction temperature of epoxy vinyl ester resin synthesis, and deep color and poor transparency of the prepared epoxy vinyl ester resin, the purpose of the present application is to provide a low-color transparent epoxy vinyl ester resin and a preparation method and application thereof.

[0009] The purpose of the present application is at least realized by one of the following technical solutions:

[0010] The first aspect of the present application provides a preparation method of a low-color transparent epoxy vinyl ester resin, which specifically comprises the following steps:

[0011] (1) uniformly mixing α, β-unsaturated carboxylic acid and styrene compound to obtain a first mixed system;

[0012] (2) adding organic peroxide to the first mixed system, uniformly mixing in an inert atmosphere, then heating to 50-80℃ and keeping warm until the viscosity reaches 15-20 Pa.s, to obtain a prepolymer system;

[0013] (3) adding unsaturated glycidyl compound, alkaline organic amine compound, substituted imidazole compound and polymerization inhibitor to the prepolymer system in sequence, uniformly mixing to obtain a second mixed system;

[0014] (4) heating the second mixed system to carry out ring-opening esterification reaction until the epoxy equivalent weight of the system is greater than 10000 g / mol, to obtain an epoxy grafting system;

[0015] (5) adding acrylic acid ester diluent to the epoxy grafting system and uniformly mixing, cooling, and filtering to obtain a low-color transparent epoxy vinyl ester resin.

[0016] Further, the raw materials of the low-chromaticity transparent epoxy vinyl ester resin include the following components in parts by weight: α, β-unsaturated carboxylic acid 70-270, styrene compound 60-260, organic peroxide 6-30, unsaturated glycidyl compound 160-300, basic organic amine compound 0.9-11, substituted imidazole compound 1.2-6.5, polymerization inhibitor 0.18-0.24, and acrylic ester diluent 160-240.

[0017] Further, in step (1), the viscosity detection temperature is 60°C.

[0018] Further, in step (1), the α, β-unsaturated carboxylic acid is an unsaturated monobasic acid.

[0019] Further, in step (1), the α, β-unsaturated carboxylic acid includes one or more of acrylic acid, methacrylic acid, and crotonic acid.

[0020] Further, in step (1), the α, β-unsaturated carboxylic acid includes one or more of acrylic acid, methacrylic acid, and crotonic acid.

[0021] Further, in step (1), the mass ratio of the α, β-unsaturated carboxylic acid to the styrene compound is 1:4-5:1.

[0022] Further, in step (1), the styrene compound includes one or more of styrene, methylstyrene, p-chlorostyrene, and tert-butylstyrene.

[0023] Further, in step (1), the styrene compound includes one or more of styrene, methylstyrene, p-chlorostyrene, and tert-butylstyrene.

[0024] Further, in step (2), the organic peroxide includes one or more of acyl peroxide, hydroperoxide, dialkyl peroxide, ester peroxide, ketone peroxide, and dicarbonate peroxide.

[0025] Further, in step (2), the organic peroxide includes one or more of benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl benzoyl peroxide, tert-butyl tert-amyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxide dicarbonate, and dicyclohexyl peroxide dicarbonate.

[0026] Further, in step (2), the organic peroxide includes one or more of benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl benzoyl peroxide, tert-butyl tert-amyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxide dicarbonate, and dicyclohexyl peroxide dicarbonate.

[0027] Further, in step (2), the inert atmosphere is a nitrogen atmosphere.

[0028] Further, in step (2), the holding time of the reaction is 0.5-1.5 h.

[0029] Further, in step (3), the unsaturated glycidyl compound contains a carbon-carbon unsaturated double bond and an epoxy group.

[0030] Further, in step (3), the unsaturated glycidyl compound is an allyl glycidyl ether, a glycidyl acrylate or a glycidyl methacrylate.

[0031] Further, in step (3), the basic organic amine compound is triethanolamine, piperidine, pyridine or benzyl dimethylamine.

[0032] Further, in step (3), the substituted imidazole compound is 2-methylimidazole, 2-phenylimidazole or 2-ethyl-4-methylimidazole.

[0033] Further, in step (3), the mass ratio of the basic organic amine compound to the substituted imidazole compound is 4:1-1:4.

[0034] Further, in step (3), the polymerization inhibitor is t-butyl hydroquinone, t-butyl pyrocatechol, p-benzoquinone, p-hydroquinone or methyl p-hydroquinone.

[0035] Further, in step (4), the temperature of the ring-opening esterification reaction is 70-90°C; and the reaction time of the ring-opening esterification is 1.0-2.0 h.

[0036] Further, in step (5), the acrylic ester diluent includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate and pentaerythritol triacrylate.

[0037] Further, in step (5), the acrylic ester diluent is hydroxyethyl acrylate, hydroxyethyl methacrylate, pentaerythritol triacrylate or tripropylene glycol diacrylate.

[0038] Further, in step (5), the cooling is to room temperature.

[0039] The second aspect of the present application provides a low color transparent epoxy vinyl ester resin, raw materials of the low color transparent epoxy vinyl ester resin include the following components in parts by weight: α, β-unsaturated carboxylic acid 70-270, styrene compound 60-260, organic peroxide 6-30, unsaturated glycidyl compound 160-300, basic organic amine compound 0.9-11, substituted imidazole compound 1.2-6.5, polymerization inhibitor 0.18-0.24, and acrylic ester diluent 160-240.

[0040] Further, the α, β-unsaturated carboxylic acid is an unsaturated monobasic acid.

[0041] Further, the α, β-unsaturated carboxylic acid is an unsaturated monobasic acid.

[0042] Further, the α, β-unsaturated carboxylic acid is an unsaturated monobasic acid.

[0043] Further, the mass ratio of the α, β-unsaturated carboxylic acid to the styrene compound is 1:4-5:1.

[0044] Further, the styrene compound includes one or more of styrene, methylstyrene, p-chlorostyrene, and tert-butylstyrene.

[0045] Further, the styrene compound includes one or more of styrene, methylstyrene, p-chlorostyrene, and tert-butylstyrene.

[0046] Further, the organic peroxide includes one or more of acyl peroxide, hydroperoxide, dialkyl peroxide, ester peroxide, ketone peroxide, and dicarbonate peroxide.

[0047] Further, the organic peroxide includes one or more of benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl benzoyl peroxide, tert-butyl tert-amyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxide dicarbonate, and dicyclohexyl peroxide dicarbonate.

[0048] Further, the organic peroxide includes one or more of benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl benzoyl peroxide, tert-butyl tert-amyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxide dicarbonate, and dicyclohexyl peroxide dicarbonate.

[0049] Further, the unsaturated glycidyl compound contains a carbon-carbon unsaturated double bond and an epoxy group in the structure.

[0050] Further, the unsaturated glycidyl compound is allyl glycidyl ether, glycidyl acrylate or glycidyl methacrylate.

[0051] Further, the basic organic amine compound is triethanolamine, piperidine, pyridine or benzyl dimethylamine.

[0052] Further, the substituted imidazole compound is 2-methylimidazole, 2-phenylimidazole or 2-ethyl-4-methylimidazole.

[0053] Further, the mass ratio of the basic organic amine compound to the substituted imidazole compound is 4:1-1:4.

[0054] Further, the polymerization inhibitor is t-butyl hydroquinone, t-butyl pyrocatechol, p-benzoquinone, hydroquinone or methyl hydroquinone.

[0055] Further, the acrylic diluent comprises one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate and pentaerythritol triacrylate.

[0056] Further, the acrylic diluent is hydroxyethyl acrylate, hydroxyethyl methacrylate, pentaerythritol triacrylate or tripropylene glycol diacrylate.

[0057] Further, the mass ratio of the α,β-unsaturated carboxylic acid, the styrene compound, the organic peroxide, the unsaturated glycidyl compound, the basic organic amine compound, the substituted imidazole compound, the polymerization inhibitor and the acrylic diluent is 200:140:6:200:1.2:1.2:0.2:200, 270:60:20:300:0.9:3.5:0.24:220, 70:240:25:160:3.5:6.5:0.22:160 or 150:260:30:200:11:3:0.18:240.

[0058] The third aspect of the present application provides the use of the low-color transparent epoxy vinyl ester resin of any one of the above or the low-color transparent epoxy vinyl ester resin prepared by the preparation method of any one of the above in preparing photocuring paint.

[0059] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0060] The low-color transparent epoxy vinyl ester resin prepared by the method has excellent optical performance and outstanding comprehensive performance, has low color and high transparency, realizes perfect balance between strength and toughness of the cast body, has excellent heat resistance and low volume shrinkage after curing, and is an excellent base resin of environment-friendly photocuring coating.

[0061] In the pre-polymerization stage of the present application, the bulk polymerization process (instead of solution polymerization) is adopted, the product has higher purity, no subsequent desolventization process is needed, the pollutant emission is effectively reduced, and the process is more in line with environmental protection requirements; at the same time, the molecular structure of the pre-polymer can be flexibly designed, the α, β-unsaturated carboxylic acid provides flexibility, the styrene crosslinking monomer endows the pre-polymer with heat resistance and rigidity, by accurately controlling the ratio of the two, a pre-polymer with excellent flexibility and heat resistance can be obtained, and the carboxyl group contained in the pre-polymer can undergo ring-opening reaction with the epoxy group, thereby preparing epoxy vinyl ester resins with different characteristics to adapt to diversified application requirements.

[0062] In the present application, a step-by-step reaction process of pre-polymerization at 50-80℃ and ring-opening esterification at 70-90℃ is adopted, and a composite catalytic system of alkaline organic amine and substituted imidazole is matched, which not only significantly reduces the synthesis temperature of the epoxy vinyl ester resin (the whole process is below 90℃), accelerates the reaction process, but also avoids the generation of by-products caused by local violent reaction, and a new medium-temperature synthesis process path is constructed. The process not only makes the reaction process more controllable, guarantees the core advantages of low color and high transparency of the product, but also effectively reduces the performance fluctuation between batches of products through quantitative and accurate control of the raw material ratio, fully meets the requirements of industrial large-scale production. DETAILED DESCRIPTION

[0063] The specific implementation of the present application is further described below in conjunction with examples, but the implementation and protection of the present application are not limited thereto. It should be noted that if the following processes are not specifically described in detail, they can be implemented or understood by referring to the prior art. If the reagents or instruments used are not marked with the manufacturer, they are considered to be conventional products that can be purchased on the market.

[0064] In the present application, the term "α, β-unsaturated carboxylic acid" refers to a carboxylic acid having an unsaturated double bond on the α and β carbon atoms adjacent to the carboxyl group.

[0065] In the present application, the term "styrene compound" refers to a class of aromatic olefins and derivatives whose molecular structure has a benzene ring directly connected to a vinyl group (-CH=CH2) as the skeleton (i.e., the basic skeleton is "C6H5-CH=CH2", corresponding to styrene). Different types of functional groups (such as alkyl, halogen, etc.) can be introduced on the vinyl group or the benzene ring through substitution reaction.

[0066] In the present application, the term "organic peroxide" refers to a class of organic compounds containing peroxide bond (-O-O-) in the molecular structure, and the peroxide bond is directly or indirectly connected to organic groups (such as alkyl, acyl, aryl, ester group, etc.).

[0067] In the present application, the term "unsaturated glycidyl compound" refers to an organic compound containing both glycidyl (epoxypropyl) and unsaturated carbon-carbon double bond (C=C) in the molecular structure, and being stably connected through ether bond or ester bond. The glycidyl (epoxypropyl) refers to the structural unit of "-O-CH2-CH(O)-CH2-", the core of which is a three-membered epoxy ring (the three-membered ring formed by the oxygen atom and two carbon atoms in CH(O)-CH2-), which has strong ring-opening activity and can react with amine, carboxylic acid, hydroxyl and other groups; the unsaturated glycidyl compound must contain at least one carbon-carbon double bond in the molecule, and the "unsaturated organic group" (such as allyl, acrylic acid group, methacrylic acid group) containing the double bond must be directly connected to the oxygen atom in the glycidyl group through ether bond or ester bond. In the present application, the unsaturated glycidyl compound includes unsaturated glycidyl ether and unsaturated glycidyl ester.

[0068] In the present application, the term "basic organic amine compound" refers to an organic compound containing a nitrogen atom directly connected to an organic group, which can be connected to aliphatic hydrocarbon group (such as methyl, ethyl), alicyclic group (such as six-membered alicyclic group), aromatic group-substituted aliphatic hydrocarbon group (such as benzyl) or directly embedded in aromatic ring (such as pyridine ring), but excluding the case where the nitrogen atom is conjugated with strong electron-withdrawing groups such as carbonyl and sulfonyl. The outermost nitrogen atom in the basic organic amine compound has 5 electrons, including 1 pair of unshared electrons and 3 single electrons, of which the 3 single electrons form three σ bonds with hydrogen or carbon atoms, and the unshared pair of electrons occupies another sp3 hybrid orbital, showing a pyramid structure, which increases the electron cloud density on the nitrogen atom, enhances the electron-donating ability and the ability to accept protons, and enhances the basicity.

[0069] In the present application, the term "substituted imidazole compound" refers to a class of organic compounds with imidazole ring (1,3-diazole) as the structural mother body, and at least one hydrogen atom on the imidazole ring (including the hydrogen on the ring carbon atom and the hydrogen on the nitrogen atom) is replaced by a non-hydrogen group (i.e. substituent) to form a class of organic compounds. In the present application, the substituted imidazole compound includes 2-position single-substituted non-fused imidazole and 2-position, 4-position double-substituted non-fused imidazole; the 2-position single-substituted non-fused imidazole refers to an imidazole derivative with a single non-fused imidazole ring as the mother body, only 1 substituent selected from C1-C2 linear alkyl (methyl, ethyl) or unsubstituted phenyl is connected to the C2 position of the imidazole ring, and the C4 position, C5 position, N1 position and N3 position are all without substituents; the "2-position, 4-position double-substituted non-fused imidazole" refers to an imidazole derivative with a single non-fused imidazole ring as the mother body, 1 substituent selected from C1-C2 linear alkyl (methyl, ethyl) or unsubstituted phenyl is connected to the C2 position of the imidazole ring, and 1 methyl substituent is connected to the C4 position, and the C5 position, N1 position and N3 position are all without substituents.

[0070] In the present application, the term "polymerization inhibitor" refers to a chemical substance that can capture active free radicals in the polymerization reaction system, inhibit the monomer chain growth process, and thus prevent or delay the unintended polymerization of unsaturated monomers (such as olefin monomers); its specific optional substances include at least one of tert-butyl hydroquinone, tert-butyl pyrocatechol, p-benzoquinone, hydroquinone and methyl hydroquinone, which can realize efficient polymerization inhibition in monomer storage, transportation or polymerization process through the reducing property of its own phenolic hydroxyl group or the free radical capturing ability of the quinone structure.

[0071] In the present application, the term "acrylate diluent" refers to a functional monomer that can reduce the initial viscosity of resin, paint, ink and other systems by its own low viscosity characteristics, improve its leveling property, workability or dispersibility, and can participate in the subsequent curing / reaction process (non-inert filling) of the system; its specific optional substances include at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate and pentaerythritol triacrylate, which can realize the dual role of system viscosity adjustment and final performance optimization according to the system requirements through the high dilution ability of single functional group (such as hydroxyethyl acrylate), the "dilution-crosslinking balance" performance of double functional group (such as tripropylene glycol diacrylate) or the "auxiliary dilution-enhanced crosslinking" characteristics of multi-functional group (such as trimethylolpropane triacrylate).

[0072] In the present application, the test method of epoxy equivalent weight refers to GB / T 4612-2008.

[0073] The first aspect of the present application provides a method for preparing a low-color transparent epoxy vinyl ester resin, specifically comprising the following steps:

[0074] (1) uniformly mixing an α, β-unsaturated carboxylic acid and a styrene compound to obtain a first mixed system;

[0075] (2) adding an organic peroxide to the first mixed system, uniformly mixing in an inert atmosphere, then heating to 50-80°C for reaction, until the viscosity reaches 15-20 Pa.s, to obtain a prepolymer system;

[0076] (3) sequentially adding an unsaturated glycidyl compound, an alkaline organic amine compound, a substituted imidazole compound and a polymerization inhibitor to the prepolymer system, uniformly mixing to obtain a second mixed system;

[0077] (4) heating the second mixed system for ring-opening esterification until the epoxy equivalent weight of the system is greater than 10,000 g / mol, to obtain an epoxy grafting system;

[0078] (5) adding an acrylic ester diluent to the epoxy grafting system and uniformly mixing, cooling, filtering to obtain the low-color transparent epoxy vinyl ester resin.

[0079] Step (2) is carried out at 50-80°C for reaction, which not only ensures the effective decomposition of the organic peroxide and avoids reaction runaway, but also precisely controls the molecular weight and viscosity of the prepolymer, providing intermediates for subsequent ring-opening esterification, and also maximally inhibits oxidation side reactions and monomer residues, ensuring low color and high transparency of the resin. The applicant has verified by experiments that too high a temperature will cause the initiator to decompose rapidly, the reaction to run away, the molecular weight distribution of the prepolymer to become wide, and even crosslinked gels to appear, which cannot be processed subsequently. At the same time, side reactions are intensified, the color is significantly increased, the molecular weight distribution is uneven, gelled particles appear, and the mechanical properties are damaged. Too low a temperature will result in a low molecular weight of the prepolymer and unstable viscosity.

[0080] In step (1), the viscosity is detected at 60°C.

[0081] In some embodiments of the present application, in step (1), the α, β-unsaturated carboxylic acid is an unsaturated monobasic acid. Preferably, in step (1), the α, β-unsaturated carboxylic acid comprises one or more of acrylic acid, methacrylic acid and butenoic acid. In some specific embodiments of the present application, in step (1), the α, β-unsaturated carboxylic acid is acrylic acid, methacrylic acid or butenoic acid.

[0082] In some embodiments of the present application, in step (1), the mass ratio of the α, β-unsaturated carboxylic acid to the styrene compound is 1:4-5:1, which balances the rigidity and flexibility of the molecular chain, and ensures that the carboxyl content is suitable for subsequent epoxy grafting reaction. The molecular structure with good flexibility and heat resistance can be designed according to different requirements, and the pre-polymer contains carboxyl groups, which can react with epoxy groups to obtain epoxy vinyl ester resins with different properties.

[0083] In some embodiments of the present application, in step (1), the styrene compound includes one or more of styrene, methylstyrene, p-chlorostyrene and tert-butylstyrene. In some specific embodiments of the present application, in step (1), the styrene compound is styrene, methylstyrene, p-chlorostyrene or tert-butylstyrene.

[0084] In some embodiments of the present application, in step (2), the organic peroxide includes one or more of acyl peroxide, hydroperoxide, dialkyl peroxide, ester peroxide, ketone peroxide and dicarbonate peroxide. Preferably, in step (2), the organic peroxide includes one or more of benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl benzoyl peroxide, tert-butyl tert-amyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate. In some specific embodiments of the present application, in step (2), the organic peroxide is benzoyl peroxide, tert-butyl benzoyl peroxide, cumene hydroperoxide or cyclohexanone peroxide.

[0085] In some embodiments of the present application, in step (2), the inert atmosphere is a nitrogen atmosphere.

[0086] In some embodiments of the present application, in step (2), the holding time of the reaction is 0.5-1.5 h.

[0087] In some embodiments of the present application, in step (3), the unsaturated glycidyl compound contains carbon-carbon unsaturated double bonds and epoxy groups in its structure. Preferably, in step (3), the unsaturated glycidyl compound is allyl glycidyl ether, glycidyl acrylate or glycidyl methacrylate.

[0088] In some embodiments of the present application, in step (3), the basic organic amine compound is triethanolamine, piperidine, pyridine or benzyl dimethylamine.

[0089] In some embodiments of the present application, in step (3), the substituted imidazole compound is 2-methylimidazole, 2-phenylimidazole or 2-ethyl-4-methylimidazole.

[0090] In some embodiments of the present application, in step (3), the mass ratio of the basic organic amine compound to the substituted imidazole compound is 4:1 to 1:4. The use of the basic organic amine compound in combination with the substituted imidazole compound synergistically accelerates the ring-opening esterification, while inhibiting yellowing. On the basis of shortening the reaction time, the ring-opening esterification reaction can be carried out at 60-90°C, saving production costs, and the reaction conditions are more controllable, without the generation of toxic substances, which is significantly superior to the conventional single catalyst system.

[0091] In some embodiments of the present application, in step (3), the polymerization inhibitor is t-butyl hydroquinone, t-butyl catechol, p-benzoquinone, hydroquinone or methyl hydroquinone.

[0092] In some embodiments of the present application, in step (4), the temperature of the ring-opening esterification reaction is 70-90°C, and the reaction time of the ring-opening esterification is 1.0-2.0h. The temperature of 70-90°C matches the reactivity of the epoxy group and the carboxyl group, ensuring efficient ring-opening esterification. Experimental verification shows that if the temperature is too high, double bond self-polymerization and oxidation side reactions will occur, resulting in resin yellowing and excessive crosslinking. If the temperature is too low, the conversion rate of the epoxy group is insufficient, affecting the mechanical properties of the resin.

[0093] In some embodiments of the present application, in step (5), the acrylic ester diluent includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate and pentaerythritol triacrylate. Preferably, in step (5), the acrylic ester diluent is hydroxyethyl acrylate, hydroxyethyl methacrylate, pentaerythritol triacrylate or tripropylene glycol diacrylate.

[0094] In some embodiments of the present application, in step (5), the cooling is to room temperature.

[0095] The second aspect of the present application provides a low-color transparent epoxy vinyl ester resin, raw materials of the low-color transparent epoxy vinyl ester resin comprising, in parts by weight: 70-270 of α, β-unsaturated carboxylic acid, 60-260 of styrene compound, 6-30 of organic peroxide, 160-300 of unsaturated glycidyl compound, 0.9-11 of basic organic amine compound, 1.2-6.5 of substituted imidazole compound, 0.18-0.24 of polymerization inhibitor, and 160-240 of acrylate diluent.

[0096] In some embodiments of the present application, the α, β-unsaturated carboxylic acid is an unsaturated monobasic acid. Preferably in the present application, the α, β-unsaturated carboxylic acid comprises one or more of acrylic acid, methacrylic acid, and crotonic acid. In some specific embodiments of the present application, the α, β-unsaturated carboxylic acid is acrylic acid, methacrylic acid, or crotonic acid.

[0097] In some embodiments of the present application, the mass ratio of the α, β-unsaturated carboxylic acid to the styrene compound is 1:4-5:1.

[0098] In some embodiments of the present application, the styrene compound comprises one or more of styrene, methylstyrene, p-chlorostyrene, and tert-butylstyrene. In some specific embodiments of the present application, the styrene compound is styrene, methylstyrene, p-chlorostyrene, or tert-butylstyrene.

[0099] In some embodiments of the present application, the organic peroxide comprises one or more of acyl peroxide, hydroperoxide, dialkyl peroxide, ester peroxide, ketone peroxide, and dioxetane peroxide. Preferably in the present application, the organic peroxide comprises one or more of benzoyl peroxide, dilauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl perbenzoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl dioxetane peroxide, and dicyclohexyl dioxetane peroxide. In some specific embodiments of the present application, the organic peroxide is benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, or cyclohexanone peroxide.

[0100] In some embodiments of the present application, the unsaturated glycidyl compound comprises a carbon-carbon unsaturated double bond and an epoxy group in its structure. Preferably in the present application, the unsaturated glycidyl compound is allyl glycidyl ether, glycidyl acrylate, or glycidyl methacrylate.

[0101] In some embodiments of the present application, the basic organic amine compound is triethanolamine, piperidine, pyridine, or benzyl dimethyl amine.

[0102] In some embodiments of the present application, the substituted imidazole compound is 2-methylimidazole, 2-phenylimidazole or 2-ethyl-4-methylimidazole.

[0103] In some embodiments of the present application, the mass ratio of the basic organic amine compound to the substituted imidazole compound is 4:1-1:4.

[0104] In some embodiments of the present application, the polymerization inhibitor is t-butyl hydroquinone, t-butyl catechol, p-benzoquinone, hydroquinone or methyl hydroquinone.

[0105] In some embodiments of the present application, the acrylic diluent includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate and pentaerythritol triacrylate. The use of low odor high flash point high boiling point acrylic monomers as diluents reduces VOC emissions, is environmentally friendly and does not adversely affect product performance. Preferably, in the present application, the acrylic diluent is hydroxyethyl acrylate, hydroxyethyl methacrylate, pentaerythritol triacrylate or tripropylene glycol diacrylate.

[0106] In some embodiments of the present application, the mass ratio of the α,β-unsaturated carboxylic acid, styrene compound, organic peroxide, unsaturated glycidyl compound, basic organic amine compound, substituted imidazole compound, polymerization inhibitor and acrylic diluent is 200:140:6:200:1.2:1.2:0.2:200, 270:60:20:300:0.9:3.5:0.24:220, 70:240:25:160:3.5:6.5:0.22:160 or 150:260:30:200:11:3:0.18:240.

[0107] The third aspect of the present application provides the use of the low color transparent epoxy vinyl ester resin of any one of the above or the low color transparent epoxy vinyl ester resin prepared by the preparation method of any one of the above in the preparation of photocurable coatings.

[0108] Example 1

[0109] Into a flask, add 200 g of methacrylic acid and 140 g of styrene, and stir well; add 6 g of benzoyl peroxide, and stir well under nitrogen protection; gradually increase the temperature to 60°C, and maintain the temperature for 1.0 hour, and detect the viscosity of 15-20 Pa.s (60°C); successively add 200 g of allyl glycidyl ether, 1.2 g of triethanolamine, 1.2 g of 2-methyl imidazole, and 0.2 g of methyl hydroquinone, and stir well; react at 70°C for 2.0 hours, and the epoxy equivalent weight is greater than 10000 g / mol; add 200 g of hydroxyethyl acrylate, and stir well; cool to room temperature, and filter to obtain a low-color transparent epoxy vinyl ester resin.

[0110] Example 2

[0111] Into a flask, add 270 g of acrylic acid and 60 g of methyl styrene, and stir well; add 20 g of tert-butyl peroxybenzoate, and stir well under nitrogen protection; gradually increase the temperature to 80°C, and maintain the temperature for 0.5 hour, and detect the viscosity of 15-20 Pa.s (60°C); successively add 300 g of glycidyl acrylate, 0.9 g of piperidine, 3.5 g of 2-phenyl imidazole, and 0.24 g of tert-butyl hydroquinone, and stir well; react at 80°C for 1.5 hours, and the epoxy equivalent weight is greater than 10000 g / mol; add 220 g of hydroxypropyl methacrylate, and stir well; cool to room temperature, and filter to obtain a low-color transparent epoxy vinyl ester resin.

[0112] Example 3

[0113] Into a flask, add 70 g of butenoic acid and 240 g of p-chlorostyrene, and stir well; add 25 g of cumene hydroperoxide, and stir well under nitrogen protection; gradually increase the temperature to 50°C, and maintain the temperature for 1.5 hour, and detect the viscosity of 15-20 Pa.s (60°C); successively add 160 g of glycidyl methacrylate, 3.5 g of pyridine, 6.5 g of 2-ethyl-4-methyl imidazole, and 0.22 g of p-hydroquinone, and stir well; react at 90°C for 1.0 hour, and the epoxy equivalent weight is greater than 10000 g / mol; add 160 g of pentaerythritol triacrylate, and stir well; cool to room temperature, and filter to obtain a low-color transparent epoxy vinyl ester resin.

[0114] Example 4

[0115] Methyl methacrylate 150 g and tert-butyl styrene 260 g were added to a flask and stirred evenly; cyclohexanone peroxide 30 g was added, nitrogen was introduced for protection, stirring was uniform, the temperature was gradually increased to 70 DEG C, the temperature was maintained, and the reaction was carried out for 1.0 h; the viscosity was 15-20 Pa.s (60 DEG C); allyl glycidyl ether 200 g, benzyl dimethylamine 11 g, 2-methyl imidazole 3 g, and methyl p-benzoquinol 0.18 g were added in sequence, stirring was sufficient, and the reaction was carried out at 80 DEG C for 2.0 h; the epoxy equivalent weight was greater than 10,000 g / mol; tripropylene glycol diacrylate 240 g was added and stirred thoroughly; the temperature was cooled to room temperature, and the low-color transparent epoxy vinyl ester resin was obtained by filtration.

[0116] Test results

[0117] Typical quality indicators of the resins obtained in the above examples are as follows:

[0118] Table 1 Common properties of the resins

[0119]

[0120] Table 2 Mechanical properties of the resin castings

[0121]

[0122] The colority of examples 1-4 is all less than or equal to 20 Hazen, and the transparency is greater than or equal to 90%. The present application can make the prepared epoxy resin have low colority and high transparency by optimizing the raw material ratio, and the mechanical properties and heat resistance of examples 1-4 are also excellent. The 25 DEG C viscosity is controlled to be 4-12 Pa・s, the processing fluidity and the mechanical properties after curing are considered, and the present application has a wide application prospect in the field of optical transparency.

[0123] Example 2 of the present application selects acrylic acid and methyl styrene as comonomers, and realizes the perfect balance of low colority, high transparency, high strength, and high toughness through the synergistic effect of the comprehensive system. The colority of example 2 is only 15 Hazen, and the yellowing risk is extremely low. The transparency of example 2 is 95%, the light transmittance is excellent, and the application requirements of optical grade can be met; the tensile strength of example 2 is 86 MPa, the impact strength is 28 kJ / m², the elongation at break is 9.8%, the bending strength is 120 MPa, and the bending modulus is 3.1 GPa, so that the cured product is not easy to be brittle, has strong anti-deformation ability, and can meet the structural bearing requirements. The solid content of example 2 is 75%, and the volume shrinkage rate after curing is low, so that the molding precision is good, and a large amount of diluent does not need to be added. The 25 DEG C viscosity of example 2 is 12 Pa・s, the fluidity can meet the industrialized processing requirements such as casting and impregnation, and the production efficiency is not affected. The heat deformation temperature of example 2 is 110 DEG C, which can meet the heat resistance requirements of most general scenarios (such as chemical equipment and composite material components).

[0124] The embodiment 3 of the present application has a high heat distortion temperature (155℃) and a low acid value (10.4 mgKOH / g), and is suitable for chemical reaction kettle lining, high-temperature pipeline and other environments which need to be resistant to acid and alkali and high temperature at the same time.

[0125] The above embodiments are only preferred embodiments of the present application, and are used to explain the present application, but not to limit the present application. The changes, replacements, modifications and the like made by those skilled in the art without departing from the spirit and essence of the present application shall all belong to the protection scope of the present application.

Claims

1. A low color transparent epoxy vinyl ester resin characterized in that, The raw material comprises the following components in parts by weight: α, β-unsaturated carboxylic acid 70-270, styrene compound 60-260, organic peroxide 6-30, unsaturated glycidyl compound 160-300, basic organic amine compound 0.9-11, substituted imidazole compound 1.2-6.5, polymerization inhibitor 0.18-0.24, and acrylic ester diluent 160-240.

2. The low color transparent epoxy vinyl ester resin according to claim 1, characterized in that, The α, β-unsaturated carboxylic acid comprises one or more of acrylic acid, methacrylic acid and crotonic acid; and / or, The styrene compound comprises one or more of styrene, methylstyrene, p-chlorostyrene and tert-butylstyrene.

3. The low color transparent epoxy vinyl ester resin according to claim 1, wherein, The organic peroxide comprises one or more of acyl peroxide, hydroperoxide, dialkyl peroxide, ester peroxide, ketone peroxide and dicarbonate peroxide; and / or, The unsaturated glycidyl compound is allyl glycidyl ether, glycidyl acrylate or glycidyl methacrylate; and / or, The basic organic amine compound is triethanolamine, piperidine, pyridine or benzyl dimethylamine; and / or, The substituted imidazole compound is 2-methylimidazole, 2-phenylimidazole or 2-ethyl-4-methylimidazole; and / or, The polymerization inhibitor is tert-butyl hydroquinone, tert-butyl pyrocatechol, p-benzoquinone, hydroquinone or methyl hydroquinone; and / or, The acrylic ester diluent comprises one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate and pentaerythritol triacrylate.

4. The low color transparent epoxy vinyl ester resin according to claim 1, wherein, The mass ratio of the α, β-unsaturated carboxylic acid, styrene compound, organic peroxide, unsaturated glycidyl compound, basic organic amine compound, substituted imidazole compound, polymerization inhibitor and acrylic ester diluent is 200:140:6:200:1.2:1.2:0.2:200, 270:60:20:300:0.9:3.5:0.24:220, 70:240:25:160:3.5:6.5:0.22:160 or 150:260:30:200:11:3:0.18:

240.

5. A process for the preparation of a low color transparent epoxy vinyl ester resin according to any one of claims 1 to 4, characterized in that, Specifically comprising the following steps: (1) uniformly mixing the α, β-unsaturated carboxylic acid and styrene compound to obtain a first mixed system; (2) adding the organic peroxide to the first mixed system, uniformly mixing in an inert atmosphere, then heating to 50-80°C and holding until the viscosity reaches 15-20 Pa.s to obtain a prepolymer system; (3) sequentially adding the unsaturated glycidyl compound, basic organic amine compound, substituted imidazole compound and polymerization inhibitor to the prepolymer system, uniformly mixing to obtain a second mixed system; (4) heating the second mixed system to perform ring-opening esterification until the epoxy equivalent weight of the system is greater than 10000 g / mol to obtain an epoxy grafting system; (5) The acrylic diluent is added to the epoxy grafting system and mixed evenly, cooled, filtered to obtain a low color transparent epoxy vinyl ester resin.

6. The preparation method according to claim 5, characterized in that, In step (1), the mass ratio of the α, β-unsaturated carboxylic acid to the styrene compound is 1:4-5:

1.

7. The preparation method according to claim 5, characterized in that, In step (2), the heat preservation reaction time is 0.5-1.5 h.

8. The preparation method according to claim 5, characterized in that, In step (3), the mass ratio of the basic organic amine compound to the substituted imidazole compound is 4:1-1:

4.

9. The preparation method according to claim 5, characterized in that, In step (4), the ring-opening esterification temperature is 70-90℃; the ring-opening esterification reaction time is 1.0-2.0 h.

10. The use of the low color transparent epoxy vinyl ester resin of any one of claims 1-4 or the low color transparent epoxy vinyl ester resin prepared by the preparation method of any one of claims 5-9 in preparing a photocuring coating.

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