JPS6339008B2 - - Google Patents

Description

Claim 1. A method for producing a vinyl ester resin with reduced viscosity comprising reacting the secondary hydroxyl groups of the vinyl ester resin with 0.05 to 1 equivalent of isocyanatoethyl methacrylate based on the secondary hydroxyl. 2. The method according to claim 1, wherein the vinyl ester resin is a diester of a polyglycidyl ether and an unsaturated monocarboxylic acid. 3. The method according to claim 1, wherein the vinyl ester resin is a diester of diglycidyl ether of bisphenol A and a monocarboxylic acid. 4. The method according to claim 2 or 3, wherein the monocarboxylic acid is methacrylic acid. 5. Process according to claim 1, in which a tin salt is used as a catalyst. Description The present invention relates to a method for producing vinyl ester resins having reduced viscosity. In many resin applications, low viscosity and good physical properties are required after minimal heat curing. However, these objectives are often completely contradictory. Polyglycidyl ether-based polymer systems, such as vinyl ester resins, have hydroxyl groups in their molecular structure. These hydroxyl groups increase the viscosity of the vinyl ester resin to a considerable extent. Generally, when performing resin processing using such a high viscosity vinyl ester resin composition, or when attempting to perform molding using such a resin composition, 50% or less of styrene or other monovinyl Requires dilution with monomer etc. The use of such diluents leads to increased manufacturing costs. It is particularly desirable to reduce the viscosity of vinyl ester resin compositions, or to reduce the amount of diluent needed to obtain a desired viscosity, while at the same time preserving the original properties of the vinyl ester resin. The drawback of high viscosity of such vinyl ester resins can be solved by reacting a vinyl ester resin with secondary hydroxyl groups with 0.05 to 1 equivalent of isocyanatoethyl methacrylate based on the secondary hydroxyl groups. The present invention has discovered that this problem can be solved. The present invention was made based on these discoveries. The reaction product (vinyl ester resin with reduced viscosity) obtained in the present invention has a lower viscosity than the corresponding unmodified resin when uncured, but when cured, the crosslinking density increases and the heat strain temperature increases. and hardness, as well as reduced water and solvent absorption. Vinyl ester resins useful in making reaction products need to have more than one secondary hydroxyl group on the polymer chain. In US Patent No.3066112 and No.3179623,
Bowen describes the production of vinyl ester resins by esterification of acrylic or methacrylic acid with polyepoxides. or,
In that patent, another method is described in which glycidyl acrylate or methacrylate is reacted with the sodium salt of bisphenol. Vinyl ester resins based on epoxy novolacs are disclosed in US Pat. No. 3,301,743. The vinyl ester resin used herein can be made from any glycidyl polyether. Useful glycidyl ethers are those of polyhydric alcohols and phenols. Such glycidyl polyethers are commercially available and may also contain at least 2 moles of epihalohydrin or glycerol dihalohydrin;
It can be easily prepared by reacting 1 mole of polyhydric alcohol or phenol with a sufficient amount of caustic soda to react with the halogen in the halohydrin. This product is characterized by more than one glycidyl ether group per molecule. Useful acids for making vinyl ester resins are ethylenically unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, cinnamic acid and their halogenated isomers. Also, US Patent No.
Also included are half esters of hydroxyalkyl acrylates or methacrylates of dicarboxylic acids such as those described in US Pat. The reaction between glycidyl ether and acid is generally
Trivalent chromium salts, such as chromium trichloride, or trivalent chromium salts, such as trichloride, or trivalent chromium salts, such as tris(N,N
-dimethylaminomethylphenol) by heating in the presence of a catalyst, such as a tertiary amine such as -dimethylaminomethylphenol). Usually, a vinyl polymerization inhibitor is added to prevent rapid polymerization. When using vinyl ester resins, it is common practice to adjust the viscosity of the liquid uncured resin with a reactive solvent, usually a copolymerizable monomer. Suitable monomers used for this purpose are vinyl aromatic monomers, such as styrene and vinyltoluene, and acrylate or methacrylate esters of lower alkanols. The amount of this reactive solvent is 60% of the total amount of resin/monomer.
Weight%. The amount of isocyanate ethyl methacrylate used is 0.05 to 1.00 equivalents per hydroxyl equivalent. When the amount is less than 0.05 equivalent, almost no change is observed in the cured product. If it is more than 1.0 equivalent,
Excess isocyanate does not react and instead reduces the desired properties of the cured product. The reaction between isocyanate and secondary hydroxyl is carried out by known methods. In a typical reaction, a polymer or polymer precursor,
After the reactive solvent and catalyst such as tin octoate are thoroughly mixed, the mixture is slowly warmed to, for example, 50°C. The isocyanate is then added while stirring. Indicates completion of the reaction. That is, heating is continued until the isocyanate band disappears from the infrared spectrum. The degree of crosslinking of the isocyanate product can be adjusted in several ways. That is, the degree of unsaturation of the polymer or precursor can be varied, and the number of hydroxyls in the raw material can also be varied. It is also possible to adjust the amount of unsaturated isocyanate to provide the desired degree of crosslinking. Additionally, some of the hydroxyl groups can be reacted with saturated aliphatic isocyanates. The products have improved properties, in particular heat strain temperature, hardness and low solvent absorption. The products have applications as straight resins and as reinforced plastics. Notable applications include fiberglass reinforced filament bent pipes, electrically conductive laminates, electrically insulating varnishes and coatings, bulk and sheet molding compounds,
and corrosion-resistant containers and container laminates. The concept of the invention is more clearly illustrated by the following examples, in which all parts and percentages are by weight. Example 1 100 parts of trimethacrylate of tris(4-glycidylphenyl)methane, 25 parts of styrene and tin octoate were mixed and heated to 50°C. Then, 47.02 parts of isocyanate ethyl methacrylate (IEM) was slowly added to the mixture while stirring, and the mixture was heated to 60°C. Further heating and stirring continue to detect the isocyanate band in the IR spectrum.
The reaction was terminated when 2280 cm ^-1 disappeared.
The amount of IEM used was 0.7 equivalents per hydroxyl equivalent. To this product was added 11.75 g of styrene. This resin was mixed with 1.5 parts of benzoyl peroxide per 100 parts of resin at 90°C for 2 hours and at 165°C for 4 hours.
Curing was carried out using a temperature schedule of 200°C for 16 hours. For comparison, trimethacrylate and 20% styrene were cured in the same manner. Samples were tested using standard methods. The results are as follows.

[Table] Other samples of the above resins were cured with 1.5 parts of benzoyl peroxide at 90°C for 2 hours and 165°C for 4 hours. The heating strain temperature of unmodified resin is 203
℃, and that of the IEM modified resin was higher than 230℃. The Valcor hardness was 42 for the former and 50 for the latter. Example 2 A resin was prepared by the same method and stoichiometry as in Example 1 using dimethacrylate of the diglycidyl ether of bisphenol A as the polymer and vinyltoluene as the reactive solvent. The resin was cured with 1.5 parts of benzoyl peroxide per 100 parts of resin at 150°C for 30 minutes. The samples were tested using standard methods and the results are shown below.

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