JPS6139325B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a glass fiber reinforced resin with excellent weather resistance, which uses methyl methacrylate and vinyl aromatic hydrocarbon as main raw materials. More specifically, the present invention provides a highly productive method for producing glass fiber reinforced resin by (1) using a partial polymerization liquid that has excellent degassing properties, excellent impregnation properties into glass fibers, and short curing time. The purpose is to provide. Another object of the present invention is to provide a method for producing a glass fiber-reinforced resin that is transparent, has excellent mechanical strength, has excellent heat discoloration resistance, weather resistance, and does not yellow. Conventionally, glass fiber-reinforced resins with excellent weather resistance made from methyl methacrylate as the main raw material have been known, and are mainly formed into plate shapes (flat plates, corrugated plates), and if necessary, the plate-shaped products are heated at 150 to 200°C. They are molded into various shapes by a so-called thermoforming method, in which they are heated and molded, and are mainly used outdoors. Such glass fiber reinforced resins are usually produced by adding a small amount of methyl methacrylate or a monomer capable of copolymerizing therewith in a reaction vessel and heating the mixture in the presence or absence of a polymerization initiator. It is obtained by impregnating glass fibers with a partially polymerized liquid and heating and curing the resulting mixture (hereinafter referred to as impregnated material). More specifically, before impregnating the glass fibers, in order to remove oxygen-containing gases dissolved in the partial polymerization solution that inhibit the polymerization reaction and cause bubbles in the glass fiber reinforced resin, It is common to perform a degassing operation. Therefore, the partial polymerization liquid used in the production of glass fiber-reinforced resins as described above must (1) have a low viscosity, that is, have excellent degassing properties and impregnation properties into glass fibers, and (2) harden in a short time. However, it is required that the amount of heat generated by the reaction during the curing process is small, the polymerization shrinkage rate is low, and (3) the quality of the obtained glass fiber reinforced resin is excellent. It is known that the viscosity of the partial polymerization liquid decreases as the degree of polymerization of the dissolved polymer decreases and as the content of the dissolved polymer decreases. on the other hand,
The higher the curing temperature and the greater the amount of polymerization initiator, the shorter the curing time; It is known that the more it increases, the shorter it becomes. Based on the above experimental facts, for a partial polymerization solution having the above-mentioned required performance, the degree of polymerization of the copolymer should be minimized within a range that does not adversely affect the mechanical strength etc. of the resulting glass fiber reinforced resin. It is judged that those with high content and low viscosity are preferable. As specific methods for obtaining the above-mentioned partial polymerization liquid, for example, a method of adjusting the amount of a polymerization initiator and a polymerization temperature used during production of the partial polymerization liquid, or a method of using a chain transfer agent are known. However, in the former two methods, it is difficult to control the polymerization reaction, and it is inconvenient to obtain a partial polymerization solution having a desired polymer content and viscosity with good reproducibility. On the other hand, the method using a chain transfer agent can produce a partially polymerized liquid having high polymer content and low viscosity with good reproducibility at a relatively low temperature. However, when producing a glass fiber reinforced resin using the partial polymerization liquid, the chain transfer agent remaining in the partial polymerization liquid not only delays the curing time of the impregnated product, but also The resins that can be obtained are inferior in terms of mechanical strength and the like. One known method for solving this problem is to add a small amount of a hydrocarbon having two or more ethylenically unsaturated groups, but this method is not fully satisfactory in terms of curing time. (JP 49-45972) On the other hand, as another method, maleic anhydride and a basic compound are not added to the obtained partial polymerization solution using a thiol compound as a chain transfer agent, and residual thiol is allowed to react with maleic anhydride. Thus, a method is known for obtaining a partially polymerized liquid having a high polymer content, low viscosity, excellent degassing properties and impregnating properties into glass fibers, and without delaying the curing time of the impregnated product as described above. (Unexamined Japanese Patent Publication No. 50-35278) However, in this method, basic compounds such as amine compounds used as catalysts for the reaction of maleic anhydride and thiol compounds remain in the glass fiber reinforced resin, and therefore during PB thermoforming. However, when used outdoors, it yellows due to the action of ultraviolet rays, etc. Therefore, it is important to solve the problem of delaying the curing time of the impregnated material while maintaining the weather resistance, especially the discoloration resistance, of the acrylic resin by using as little amount of the basic compound as possible. It was hot. In view of these problems of the conventional method, the inventors of the present invention have conducted intensive research and have solved all the drawbacks of the conventional method as described above. In other words, the partial polymerization liquid obtained by the present invention has a low viscosity, has excellent degassing properties and impregnation properties into glass fibers, has a sufficiently short curing time for the impregnated material, is transparent, has no air bubbles, and is suitable for thermoforming. They have achieved a method for producing glass fiber reinforced resin that does not yellow due to heat during use or ultraviolet rays during outdoor use. That is, the present invention provides (A) 85 to 60% by weight of methyl methacrylate, (B) 15 to 40% by weight of vinyl aromatic hydrocarbon, and (C) ethylene based on the total amount of (A) and (B). Add at least one type of (D) thioglycolic acid and its ester compounds to a mixture of 5.0% by weight or less of hydrocarbons having two or more unsaturated groups, based on the total amount of (A) and (B).
4.0% by weight was added to cause a copolymerization reaction, and the copolymerization reaction was stopped before the mixture gelled, and then 0.3 to 0.6 times the molar amount of maleic anhydride to (D),
and impregnating an alkali-containing fiber with a partial polymerization solution obtained by adding a basic compound in an amount less than 0.01 times by mole,
This is a method for producing a glass fiber reinforced resin containing methyl methacrylate as a main component, which is characterized by heating and curing the impregnated material obtained. The proportion of methyl methacrylate used in the present invention is 85 to 60% by weight, based on the total amount of methyl methacrylate and vinyl aromatic hydrocarbon, but it is particularly preferably less than 80% by weight to 65% by weight. Typical vinyl aromatic hydrocarbons used in the present invention are styrene, vinyltoluene, vinyl xylene, etc., and the usage ratio is 15% to the total amount of methyl methacrylate and vinyl aromatic hydrocarbon.
~40% by weight, but amounts exceeding 20% by weight ~35% by weight are preferred. Compounds having two or more ethylenically unsaturated groups capable of copolymerization with methyl methacrylate and vinyl aromatic hydrocarbons (hereinafter abbreviated as polyvinyl compounds) used in the present invention include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane. Typical examples include methacrylates such as trimethacrylate, tetramethylolmethanetetramethacrylate, acrylates such as ethylene glycol diacrylate, trimethylolethane triacrylate, and tetramethylolmethanetetraacrylate, and divinylbenzene. It is not more than 5.0% by weight, based on the total amount of hydrocarbons, but 0.2 to 5.0% by weight is particularly preferred. Thioglycolic acid and its ester compounds used in the present invention include thioglycolic acid, ethyl thioglycolate, isopropyl thioglycolate,
Typical examples include octyl thioglycolate, and the proportion used is 0.03 to 4.0% by weight based on the total amount of methyl methacrylate and vinyl aromatic hydrocarbon.
However, 0.06 to 3.0% by weight is particularly preferred. The ratio of maleic anhydride used in the present invention is 0.3 to 6.0 times the molar amount of at least one of the thioglycolic acid and its ester,
Particularly preferred is a 0.5 to 5.0 molar amount. Typical basic compounds used in the present invention include primary amines such as methylamine and ethylamine, secondary amines such as dimethylamine, tertiary amines such as triethylamine and tributylamine, and triazole compounds. The usage ratio is less than 0.01 times the mole of thioglycolic acid and its ester compound, preferably
The amount is 0.001 to 0.009 moles. The glass fiber used in the present invention is known to have a refractive index of 1.51 to 1.53, and its usage ratio is 30% by weight or less based on the total amount of the partially polymerized liquid and the alkali-containing glass fiber. It's normal. The reason why the compounds copolymerizable with methyl methacrylate used in the present invention are limited to vinyl aromatic hydrocarbons in addition to a small amount of polyvinyl compounds is based on the following reason. In other words, if alkyl acrylate, alkyl methacrylate, or acrylonitrile is used as a compound that can be copolymerized with methyl methacrylate, the refractive index of the copolymer obtained by combining these will differ from the refractive index of the alkali-containing glass fiber. In comparison, the difference is large, and the transparency of the resulting glass fiber reinforced resin is poor, resulting in a product that significantly impairs its commercial value.
Also, the usage ratio of methyl methacrylate and vinyl aromatic hydrocarbon is 85%.
~60% by weight, i.e. vinyl aromatic hydrocarbons 15
The reason for limiting the amount to 40% by weight is as follows.
In other words, the proportion of vinyl aromatic hydrocarbons used is 15
less than % by weight, i.e. methyl methacrylate
If the amount exceeds 85% by weight, the resulting glass fiber reinforced resin will have poor transparency. On the other hand, when the proportion of vinyl aromatic hydrocarbon used exceeds 40% by weight, that is, the proportion of methyl methacrylate used is less than 60% by weight, the curing time of the impregnated product is shortened by the addition of maleic anhydride and a basic compound. The degree of oxidation is extremely small, and the resulting glass fiber reinforced resin has poor transparency. Furthermore, among the thiol compounds, thioglycolic acid and its ester compounds were selected as molecular weight regulators for the following reason. That is, compared to other thiol compounds, such as alkyl mercaptans, the thiol compounds have a greater effect on controlling the molecular weight and also have higher reactivity with maleic anhydride, so the proportion of basic compounds used as catalysts should be reduced. It is possible to shorten the curing time of the partial polymerization solution even in a very small amount, and this effect is particularly remarkable for thioglycolic acid. Moreover, the reason why the proportion used is limited to 0.03 to 4.0% by weight is based on the following reason. That is, outside this range, the above-mentioned required performance for the partial polymerization solution cannot be satisfied. Furthermore, the reason why the proportion of maleic anhydride used is limited to 0.3 to 6.0 moles per at least one of thioglycolic acid and its ester compounds is based on the following reason. That is,
If the amount is less than 0.3 times the amount by mole of the thiol compound, it will not be possible to sufficiently eliminate the delay in curing time of the impregnated product due to the thiol compound remaining in the partial polymerization solution;
This is because if the amount exceeds 6.0 moles, yellowing of the obtained glass fiber reinforced resin due to heat, ultraviolet rays, etc. will be significant. Furthermore, the glass fibers used in the present invention are limited to alkali-containing glass fibers (refractive index 1.51 to 1.53) for the following reasons. In other words, when the refractive index exceeds 1.53, the amount of vinyl aromatic hydrocarbon used must exceed 40% by weight based on the total amount of methyl methacrylate and vinyl aromatic hydrocarbon to obtain a transparent glass fiber reinforced resin. Therefore, there is almost no effect of shortening the curing time of the impregnated material by adding maleic anhydride and a basic compound. Also, the refractive index
Alkali-containing glass fibers with a ratio of less than 1.51 are not known in practice. According to the method of the present invention, by limiting the compounds that can copolymerize with methyl methacrylate and their proportions, and by limiting the thiol compounds to thioglycolic acid and its ester compounds, it is possible to By adding the following basic compound, the viscosity is low, that is, the deaeration property and the impregnating property to the alkali-containing glass fiber are excellent, and the curing time of the obtained impregnated product is sufficiently shortened.
In other words, the productivity of glass fiber reinforced resin is high;
Furthermore, the resulting glass fiber reinforced resin has excellent transparency and does not yellow due to the effects of heat during hot molding or ultraviolet rays during outdoor use. In the present invention, methyl methacrylate, vinyl aromatic hydrocarbon and polyvinyl compound are used in thioglycolic acid and thioglycolic acid ester,
In order to carry out the aromatic polymerization reaction in the presence of at least one species, it is usual to use a polymerization initiator or carry out thermal polymerization at 50 to 120°C. Of course, compounds other than polyvinyl compounds that can copolymerize with these compounds, such as butyl acrylate, 2-ethylhexyl acrylate, etc., may be used in combination in small amounts to the extent that the effects of the present invention are not impaired. In the present invention, the polymerization rate of the partial polymerization liquid is 5 to 50% by weight based on the total amount of methyl methacrylate, vinyl aromatic hydrocarbon, and polyvinyl compound. In the present invention, after copolymerizing the mixed solution of methyl methacrylate, vinyl aromatic hydrocarbon, and polyvinyl compound to an extent that does not result in gelation, the reaction is stopped by cooling or by adding a polymerization inhibitor. is normal. In the present invention, the time of addition of maleic anhydride is at the end of the copolymerization reaction or after the end of the copolymerization reaction (just before starting the curing reaction), and the time of addition of the basic compound is before or after the addition of maleic anhydride. Either is fine. The reaction between maleic anhydride and thioglycolic acid and its ester compounds is suitably carried out at room temperature to 90°C, and the time required for the reaction is several minutes to several hours. To impregnate alkali-containing glass fibers with the partial polymerization solution of the present invention and cure the impregnated product to obtain a molded article, a method using a polymerization initiator such as an azo compound or a peroxide, benzoin ethyl ether, and ultraviolet rays are used. This method is common. Further, the curing temperature during curing is preferably 120°C or less. When carrying out the present invention, for example, various polymers such as methyl methacrylate-styrene copolymer may be added to the mixed solution of methyl methacrylate, vinyl aromatic hydrocarbon and polyvinyl compound in advance to the extent that the effects of the present invention are not impaired. There is no problem in adding the aforementioned polymers, polyvinyl compounds, and compounds capable of copolymerization reactions other than polyvinyl compounds to the partial polymerization solution obtained by dissolving or stopping the copolymerization reaction. In the present invention, in addition to alkali-containing glass fibers, ultraviolet absorbers, coloring agents, and the like can be added to the partial polymerization solution within a range that does not impair the effects of the present invention, thereby making it possible to produce molded articles of various shapes. Hereinafter, the usefulness of the present invention will be explained with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is changed. Note that parts used in the following examples mean parts by weight. Example 1 Methyl methacrylate, styrene vinyl toluene methylol propane trimethacrylate (hereinafter abbreviated as TMPT) and thioglycolic acid (hereinafter abbreviated as TGA) consisting of quantitative proportions shown in Table 1.
To the mixture, 0.001 part of azobisisobutyronitrile as a polymerization initiator was charged into a reaction vessel equipped with a reflux condenser and a stirrer, and after purging the inside of the reaction vessel with nitrogen, the mixture was heated to 100°C in a nitrogen atmosphere. The copolymerization reaction was carried out for the time shown in Table 1, and the mixture was rapidly cooled to 70°C to obtain a partial polymerization solution having the polymerization rate and viscosity shown in Table 1 and containing no insoluble gel. Maleic anhydride (hereinafter abbreviated as MLA) and tributylamine (hereinafter abbreviated as TBA) in the amounts shown in Table 1 are added to the partial polymerization solution.
was added and kept under stirring at 70°C for 2 hours, then cooled to room temperature. Next, for partial polymerization liquids with a viscosity (25°C) higher than 600 cp, the corresponding Table 1
A mixed solution of methyl methacrylate styrene and vinyl toluene TMPT having the quantitative ratio shown in the following was added and mixed to obtain a diluted partial polymerization solution having a viscosity of 600 cp. After adding and mixing bis-4-t-butylcyclohexyl peroxydicarbonate (hereinafter abbreviated as BCHP) as a polymerization initiator to this diluted partial polymerization solution, it was degassed under reduced pressure, and this mixed solution was applied on cellophane. On top, alkali-containing glass fibers (refractive index 1.52, 2″ chopped strands) were uniformly dropped and dispersed in the amount shown in Table 1, and after the alkali-containing glass fibers were sufficiently impregnated with the partial polymerization liquid,
This impregnated product was covered with cellophane, making sure that no trapped air bubbles remained. The cellophane-coated impregnation on both sides was fixed in a steel frame. By heating this in a hot air heating furnace at 65°C, a peak was observed in the temperature of the impregnated material due to polymerization heat generation. (Hereinafter, the time from when the temperature of the impregnated material reaches 35°C until the exothermic peak is defined as the curing time) After the exothermic peak is observed,
The temperature was maintained at 115° C. for 3 minutes to obtain a glass fiber reinforced resin plate with a thickness of 1.2 mm. The glass fiber reinforced resin plate thus obtained was evaluated for transparency, resistance to heat discoloration, and weather resistance. (1) Transparency was determined by visual observation. (2) Heat resistance to discoloration was determined by holding the test piece in an air bath at 180°C for 1 hour, and observing the degree of discoloration with the naked eye after the test. (3) Weather resistance was determined by exposing the test piece for 2000 hours using a sunshine weather meter.

[Table] The degree of discoloration was determined visually. The results obtained in the above tests are also listed in Table 1. Example 2 0.001 part of azobisisobutyronitrile was added as a polymerization initiator to a mixture of methyl methacrylate, styrenetetramethylolpropanetetramethacrylate (hereinafter abbreviated as TMMT) and a thiol compound in the quantitative proportions shown in Table 2. was charged into a reaction vessel equipped with a reflux condenser and a stirrer, and after purging the inside of the reaction vessel with nitrogen, it was heated to 100°C in a nitrogen atmosphere, allowed to undergo a copolymerization reaction for the time shown in Table 2, and then rapidly cooled to 65°C. A partially polymerized solution having a polymerization rate and viscosity shown in 2 and containing no insoluble gel was obtained. MLA and TBA in the amounts shown in Table 2 were added to the partial polymerization solution, and the mixture was kept under stirring at 65° C. for 1.5 hours, and then cooled to room temperature. Next, for partial polymerization liquids with a viscosity (25°C) higher than 200 cp, the corresponding Table 2
Methyl methacrylate consisting of the quantitative proportions shown in
Add and mix the styrene TMMT mixture,
A diluted partial polymerization solution with a viscosity of 200 cp was obtained. After adding and mixing BCHP as a polymerization initiator to this diluted partial polymerization solution, it was degassed under reduced pressure, and this mixed solution was applied on cellophane. strand) in Table 2
After the alkali-containing glass fibers were sufficiently impregnated with the partially polymerized liquid, the impregnated product was covered with cellophane so that no trapped air bubbles remained. The impregnated material was cured under the following conditions to obtain a glass fiber reinforced resin plate with a thickness of 1.2 mm.
The heat discoloration resistance and weather resistance were evaluated, and the obtained results are also listed in Table 2.

[Table] Example 3 77 parts of methyl methacrylate, 23 parts of styrene,
To a mixture of 2.5 parts of TMPT and 0.45 parts of thioglycolic acid, 0.001 part of azobisisobutyronitrile as a polymerization initiator was charged into a reaction vessel equipped with a reflux condenser and a stirrer, and the mixture was heated in the same manner as in Example 1 for 5.0 hours. The copolymerization reaction was carried out and the mixture was rapidly cooled to 70° to obtain a partial polymerization solution with a polymerization rate of 25.0% and a viscosity (25°C) of 270 cp. Consisting of the quantitative proportions shown in Table 3 for the partial polymerization solution.
MLA and triethylamine (hereinafter abbreviated as TEA)
After adding and keeping under stirring for 1.5 h at 65 °C,
Cooled to room temperature. Regarding this partial polymerization liquid, a glass fiber reinforced resin with a thickness of 1.2 mm was obtained under the same curing recipe and curing temperature conditions as in Example 1, and the same evaluation as in Example 1 was performed, and the results are also listed.

【table】

Claims (1)

[Claims] 1 (A) 85 to 60% by weight of methyl methacrylate, (B) 15 to 40% by weight of vinyl aromatic hydrocarbon, and (C) ethylenically unsaturated group based on the total amount of (A) and (B). Add at least one of (D) thioglycolic acid and its ester compounds to a mixture containing 2 or more compounds at 5.0% by weight or less, based on the total amount of (A) and (B), from 0.03 to 5.0% by weight.
4.0% by weight was added to cause a copolymerization reaction, and the copolymerization reaction was stopped before the mixed solution gelled. Then, 0.3 to 6.0 molar amount of maleic anhydride and 0.01 molar amount of maleic anhydride to (D) were added. Glass fiber reinforced with methyl methacrylate as the main component, which is characterized by adding less than twice the mole amount, impregnating the obtained partial polymerization liquid into alkali-containing glass fibers, and heating and curing the impregnated product. Method of manufacturing resin.