JPS6214174B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention involves impregnating glass fibers with a polymerizable liquid composition obtained by dissolving cumyl peroxyneodecanoate and/or monoalkyl cumyl peroxyneodecanoate as a polymerization initiator in a syrup mainly composed of methyl methacrylate. Alternatively, the present invention relates to a method for manufacturing a glass fiber reinforced resin plate by mixing and polymerizing and curing the mixture. In recent years, flat plates and corrugated plates made of glass fiber-reinforced resins containing methyl methacrylate as the main component have become increasingly useful as building materials, agricultural lighting boards, and structures such as cooling towers used outdoors due to their excellent weather resistance. is highly regarded and widely used. However, due to its low production efficiency, it has the disadvantage of higher manufacturing costs than commercially available glass fiber reinforced unsaturated polyester resin sheets.Therefore, there is a strong demand for improved productivity, and high production efficiency that polymerizes and cures in a short time is required. Polymerization technology was required. On the other hand, in general, if the polymerization and curing time is shortened, disadvantages such as foaming of the glass fiber reinforced resin plate during polymerization and curing, poor crazing resistance, and significant decrease in strength occur. Therefore, as is known from, for example, Japanese Patent Publication No. 47-7637 and Japanese Patent Application Laid-open No. 49-45972, it has not been possible to reduce the polymerization and curing time to 20 to 40 minutes. The present invention provides a method for manufacturing a glass fiber reinforced resin plate with low manufacturing cost and excellent quality. A polymerizable liquid composition in which cumyl peroxy neodecanoate and/or monoalkyl cumyl peroxy neodecanoate, which is a polymerization initiator for a syrup containing a saturated monomer and having a polymerization rate of 15 to 35% by weight, is dissolved. It is characterized in that glass fibers are impregnated with or mixed into glass fibers and then polymerized and cured to efficiently produce glass fiber-reinforced methacrylic resin plates. Furthermore, the present invention has discovered a method for producing a glass fiber-reinforced methacrylic resin of excellent quality while shortening the polymerization and curing time after impregnating or mixing the composition into glass fibers to within 15 minutes. By the way, in order to make glass fiber-reinforced methacrylic resin boards lower in manufacturing cost than commercially available glass fiber-reinforced unsaturated polyester resin boards and to have excellent marketable quality, the following four conditions must be met. is necessary. (1) Polymerization and curing time is within 15 minutes, preferably within 10 minutes. (2) No air bubbles should be formed in the resin plate during polymerization and curing;
In other words, polymerization and foaming should not occur. (3) The strength of the manufactured resin board is excellent. (4) The manufactured resin board has excellent crazing resistance and weather resistance. That is, when the polymerizable liquid composition is impregnated into or mixed with glass fibers and then polymerized and cured, the polymerization and curing time must be within 15 minutes, preferably within 10 minutes to produce a glass fiber-reinforced unsaturated polyester resin board. This shows that improving production efficiency is an essential condition. Furthermore, the presence of air bubbles in the manufactured resin plate impairs its commercial value, and since these air bubbles are generated during polymerization and curing, it is particularly necessary to appropriately select polymerization conditions. In addition, since the manufactured resin boards are used as building materials for agricultural structures, they are required to have strength, so it is necessary to not only improve the production efficiency of the resin boards but also to take care not to reduce their strength. In addition, since the manufactured resin boards are often used outdoors, they have excellent crazing resistance to prevent crazing on the surface of the resin board, and are also resistant to coloring, discoloration, and whitening. It is also necessary to have excellent weather resistance so that it does not deteriorate. The four conditions mentioned above are essential conditions in order to make the manufacturing cost of glass fiber reinforced methacrylic resin board lower than that of glass fiber reinforced unsaturated polyester resin board, and to make it marketable and of excellent quality. Four conditions must be satisfied simultaneously. The present invention provides a method for manufacturing a glass fiber-reinforced methacrylic resin board that satisfies the above four conditions at the same time. That is, in particular, the present invention uses cumyl peroxyneodecanoate or/and monoalkyl cumyl peroxyneodecanoate as a polymerization initiator in a specific range of amounts used, and under conditions of a specific heat curing temperature range. Below, glass fibers are impregnated with a polymerizable liquid composition consisting of syrup with a polymerization rate of 15 to 35% by weight, which contains methyl methacrylate as a main component and a polyfunctional unsaturated monomer having two or more unsaturated groups. Alternatively, the inventors have discovered a method for manufacturing a glass fiber reinforced methacrylic resin plate that satisfies the above four conditions at the same time by polymerizing and curing the mixture after mixing. Examples of cumyl peroxy neodecanoate and/or monoalkyl cumyl peroxy neodecanoate which are the polymerization initiators of the present invention include cumyl peroxy neodecanoate, isopropyl cumyl peroxy neodecanoate, Normal butyl cumyl peroxyneodecanoate,
Isobutylcumyl peroxyneodecanoate,
sec-Butylcumylperoxyneodecanoate, tert-butylcumylperoxyneodecanoate, 2-ethylhexylcumylperoxyneodecanoate, ethoxycumylperoxyneodecanoate, 3-methoxybutylcumylperoxyneodecanoate One type or a combination of two or more types selected from decanoate and the like can be used. Furthermore, if the weight is 10 times or less of the amount of cumyl peroxyneodecanoate or/and morealkyl cumyl peroxyneodecanoate used in the present invention, for the purpose of handling, work safety, etc. , plasticizers such as dibutyl phthalate and dioctyl phthalate with which cumyl peroxy neodecanoate is difficult to react with monoalkyl cumyl peroxy neodecanoate, and mineral spirits and cumyl peroxy neodecanoate such as toluene. A diluent that does not easily react with the monoalkyl cumyl peroxyneodecanoate can be used with the cumyl peroxyneodecanoate or/and the monoalkyl cumyl peroxyneodecanoate. The amount of cumyl peroxy neodecanoate or/and monoalkyl cumyl peroxy neodecanoate used as a polymerization initiator of the present invention is based on 100 parts by weight of the syrup of the present invention. The relationship between the molar parts of monoalkyl cumyl peroxyneodecanoate and the heat curing temperature (°C) is shown in Figure 1 at points A (1×10 ^-4 , 90), B (1×10 ^-2 , 85), C.
(3×10 ^-2 , 60) and D (1×10 ^-4 , 65) are connected with straight lines to form a closed region. and the amount of monoalkyl cumyl peroxyneodecanoate used.
This is necessary in order to manufacture a resin plate that satisfies the four conditions mentioned above. Furthermore, the syrup used in the present invention, which is mainly composed of methyl methacrylate and contains a polyfunctional unsaturated monomer having two or more unsaturated groups, has a polymerization rate of 15.
-35% by weight, preferably 20-30% by weight, and the viscosity of the syrup is 0.2 at 25°C.
It is preferable that it is more than poise. If the polymerization rate of the syrup is less than 15% by weight, the production efficiency of the resin plate will be poor, and the number of molar parts of the cumyl peroxy neodecanoate and/or monoalkyl cumyl peroxy neodecanoate as a polymerization initiator and the heating The relationship between the curing temperature (°C) and the polymerization curing time is 15% even if polymerization is carried out under the conditions within the closed region shown in Figure 1.
It becomes difficult to produce resin plates of excellent quality within minutes, and even more so, it is impossible to reduce the polymerization and curing time to within 10 minutes. On the other hand, when the polymerization rate of the syrup is more than 35% by weight, the viscosity of the syrup increases, making it difficult to impregnate or mix the polymerizable liquid composition into glass fibers and making it difficult to remove air bubbles, which is not preferable. The viscosity of syrup is at 25℃
It is preferable that it is 0.2 poise or more, and if it is 0.2 poise or less, foaming during polymerization and curing is likely to occur when the polymerization and curing time is shortened, and the quality of the manufactured resin board, especially the strength and craze resistance, is likely to decrease. . On the other hand, if the syrup viscosity becomes high, it becomes difficult to impregnate or mix the polymerizable liquid composition into glass fibers, and it becomes difficult to remove air bubbles, so the upper limit of the syrup viscosity is usually up to 100 poise. That is,
The syrup of the present invention preferably has a polymerization rate of 15 to 35% by weight and a viscosity of 0.2 to 100 poise at 25°C. Furthermore, in the present invention, the number average degree of polymerization of the polymer in the syrup is 500 or more, the weight average degree of polymerization is 2,500 or less, and the polymerization degree is expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization of the polymer. The polydispersity of the distribution is
It is preferable to use a syrup with a hardness of 2.5 or less. Generally, the viscosity of the syrup is determined by the polymerization rate of the syrup and the weight average polymerization degree of the polymer, and the higher the viscosity of the syrup, the higher the viscosity of the syrup. It is preferable to lower the degree. However, even if the syrup has a polymerization rate of 15 to 35% by weight and a viscosity of 0.2 to 100 poise at 25°C, if the number average polymerization degree of the polymer is low, the machinability when cutting the manufactured resin plate, and the resin Defects such as deterioration of the strength of the board itself or crazing resistance occur, and these demerits reduce the number average degree of polymerization of the polymer in the syrup.
The present inventors found that the value changes rapidly after reaching 500. Polymers have a degree of polymerization distribution, and the weight average degree of polymerization is greater than the number average degree of polymerization, and the degree of polymerization is typically expressed as the ratio of the two, polydispersity, as a measure of the breadth of the degree of polymerization distribution. As mentioned above, the viscosity of the syrup increases as the polymerization rate of the syrup increases and as the weight average degree of polymerization of the polymer increases. In order to increase the polymerization rate of the syrup, to make it easier to impregnate or mix the polymerizable liquid composition into glass fibers, and to make it easier to remove air bubbles, it is required to lower the weight average degree of polymerization. In the present invention, the viscosity of the syrup at 25°C is
Increasing the polymerization rate to 15 to 35% by weight in the range of 0.2 to 100 poise improves production efficiency, and improves the quality of the resin plate produced, especially machinability when cutting the resin plate, and the quality of the resin plate itself. In order to have no defects in strength or crazing resistance, the number average degree of polymerization of the polymer in the syrup is 500 or more, the weight average degree of polymerization is 2500 or less, and the weight average degree of polymerization of the polymer is It is preferable to use a syrup whose polydispersity of the degree of polymerization distribution expressed as a ratio to the number average degree of polymerization is 2.5 or less. The syrup used in the present invention is mainly composed of methyl methacrylate and contains a polyfunctional unsaturated monomer having two or more unsaturated groups, and the amount of the polyfunctional unsaturated monomer is determined throughout the syrup. relative to weight
Examples of the polyfunctional unsaturated monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, and decamethylene glycol. Diacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, allyl acrylate, crotyl acrylate, mesaryl acrylate, tetramethylolmethane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol Dimethacrylate, decamethylene glycol dimethacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, crotyl methacrylate, mesaryl methacrylate,
Tetramethylolmethane trimethacrylate, divinylbenzene, triallyl isocyanurate,
diallyl phthalate, diallyl isophthalate,
At least one polyfunctional unsaturated monomer selected from diallyl terephthalate, diallylbenzene, diethylene glycol bisallyl carbonate, diallyl maleate, diallyl fumarate, diallylitaconate, divinyl ether, and dimesalyl ether is used. . If the amount of the polyfunctional unsaturated monomer is less than 0.2% by weight based on the total weight of the syrup, the strength of the produced resin plate will be low and the crazing resistance will also be low, which is not preferable; If the amount is too large, the surface of the resin plate may partially dent when the glass fiber is impregnated or mixed with the polymerizable liquid composition and then polymerized and cured, which impairs the appearance, which is not preferable. The present invention uses methyl methacrylate as the main component and 2
Cumylperoxyneodecanoate or/and monoalkylcumylperoxyneodecanoate is added to the syrup with a polymerization rate of 15 to 35% by weight containing a polyfunctional unsaturated monomer having three or more unsaturated groups as a polymerization initiator. After impregnating or mixing glass fiber with a polymerizable liquid composition in which noate is dissolved, the temperature at which the composition polymerizes is determined by heating and curing temperature (°C) and cumyl peroxyneodecanoate or/and monoalkyl cumyl peroxyneoate. By polymerizing and curing the composition under conditions in which the relationship with the amount of decanoate used falls within the closed region shown in FIG. This makes it possible to manufacture resin plates. The amounts of cumyl peroxy neodecanoate and/or monoalkyl cumyl peroxy neodecanoate in FIG. 1 of the present invention are expressed on a logarithmic scale. In addition to cumyl peroxy neodecanoate and/or monoalkyl cumyl peroxy neodecanoate, which are the polymerization initiators of the present invention, an amount within a range that does not cause polymerization foaming in the resin plate produced by the present invention is added. If necessary, other polymerization initiators may be used in combination, such as lauroyl peroxide or tertiary butyl peroxypivalate. In addition, in the present invention, the syrup may contain heat stabilizers, ultraviolet absorbers, colorants, various fillers, etc., as necessary, as long as the amounts are within the range that achieves the purpose of the present invention. . Furthermore, the syrup of the present invention may contain an unsaturated monomer copolymerizable with methyl methacrylate, for example, for the purpose of improving the adhesion between the glass fibers and methacrylic resin of a glass fiber reinforced methacrylic resin plate. In addition, if necessary, the syrup may contain other unsaturated monomers copolymerizable with methyl methacrylate, such as carboxyl groups such as acrylic acid and methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, etc. An unsaturated monomer having a hydroxyl group, an epoxy group such as glycidyl acrylate, glycidyl methacrylate, or an acrylic acid alkyl ester may also be used. 2 containing the metal methacrylate of the present invention as the main component
In order to prepare a syrup with a polymerization rate of 15 to 35% by weight containing a polyfunctional unsaturated monomer having three or more unsaturated groups, methyl methacrylate is partially polymerized to form a syrup, and then the polyfunctional Either a polyfunctional unsaturated monomer is added to this syrup to achieve a predetermined polymerization rate and composition, or a mixture of methyl methacrylate and the polyfunctional unsaturated monomer is partially polymerized to achieve a predetermined polymerization rate and composition. Alternatively, there is an adjustment method in which a polymer obtained by polymerizing methyl methacrylate is dissolved in a mixture of methyl methacrylate and the polyfunctional unsaturated monomer to obtain a predetermined polymerization rate and composition.
At any stage of these preparation methods, the additives, fillers, and unsaturated monomers copolymerizable with methyl methacrylate may be added and mixed. The manufacturing equipment to which the present invention is applied is not particularly limited as long as it is an equipment that manufactures glass fiber reinforced resin plates generally known as flat plates or corrugated plates, and can manufacture glass fiber reinforced unsaturated polyester resin plates. It goes without saying that the present invention can be applied to devices. When carrying out the manufacturing method of the present invention, a mold of glass, cellophane film, polyester film, polyvinyl alcohol film, polyethylene film, polypropylene film, aluminum, iron, stainless steel, etc., which can be heated and cured into the desired shape, is used. Alternatively, it can be formed into any shape, such as a flat plate or a corrugated plate, between continuously moving belts made of stainless steel or the like or between the films, and post-processing by thermoforming or the like is also possible. The glass fibers used in the present invention are conventionally known and have shapes such as roving, surfacing mat, chopped strand, chopped strand mat, satin weave, lattice weave, plain weave, open plain weave, It is suitable for use in any shape such as twill weave or net, and can be made of any type such as E glass fiber or C glass fiber, and the ratio of use with the polymerizable liquid composition is the same as before.
It is preferably 10 to 40% by weight based on the weight of the normally produced resin plate. In the present invention, glass fibers are impregnated or mixed with the polymerizable liquid composition and then polymerized and strengthened to obtain a resin plate. However, the heating curing temperature may be kept constant throughout, or may be changed stepwise or continuously. Further, heat treatment may be performed subsequent to heat curing for the purpose of reducing residual monomer in the resin plate to be produced. Generally heat treatment temperature is 110~
150°C is preferred. The glass fiber-reinforced methacrylic resin plate obtained by the present invention is inexpensive to manufacture and has excellent quality, and is widely used as a building material or a structure for agricultural use. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. The percentages in the examples are percentages by weight. In addition, polymerization foaming in the examples was determined by visually observing the obtained resin plate to determine the presence or absence of bubbles, and the craze resistance of the obtained resin plate was determined by adding 10% to ethyl acetate.
The presence or absence of crazing was determined by the naked eye after soaking for a minute, and the bending strength was determined by ASTM D-790. Weather resistance was determined by accelerated exposure testing in accordance with ASTM D-1499, and the appearance was determined by the naked eye. It was judged. Example 1 Methyl methacrylate monomer containing 0.09% of azobisdimethylvaleronitrile was preheated to 80°C using a jacketed single tube, and the mixture was placed in a stirred tank reactor equipped with a ribbon-shaped stirring blade. It was fed continuously so that the average residence time was 3.6 minutes. Stirring was carried out at a speed of 800 revolutions per minute, maintaining the reactor temperature at 140° C. and pressure at 3 atmospheres gauge. The syrup leaving the reactor was rapidly cooled to obtain a syrup with a polymerization rate of 30% and a viscosity of 22 poise at 25°C. The number average degree of polymerization of the polymer in the syrup was 600, and the weight average degree of polymerization was 1224. Therefore, the polydispersity of the polymerization degree distribution expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization was 2.04. A polymerizable liquid composition is prepared by mixing and dissolving an appropriate amount of cumyl peroxyneodecanoate as a polymerization initiator and an appropriate amount of ethylene glycol dimethacrylate as a polyfunctional unsaturated monomer in this syrup and degassing it under reduced pressure. Glass fiber (manufactured by Nippon Sheet Glass Fiber Co., Ltd.)
CR-213-LA-7S) is injected into a polymer mold for a flat plate uniformly filled so that the final resin plate contains 25% to impregnate the glass fibers, and then this polymer mold is immersed in a heating bath. It was polymerized and cured. During this time,
The temperature rise due to polymerization exotherm was measured, and the time required to reach the maximum temperature is shown as the polymerization curing time in Table 1. After reaching the maximum temperature, the glass was cooled to room temperature and was molded into a glass with a thickness of about 1 mm from inside the polymerization mold. The fiber-reinforced methacrylic resin board was taken out. As shown in Table 1, no polymerization foaming was observed in any of the resin plates obtained despite the extremely short polymerization time, and the crazing resistance was also good. Furthermore, no change in appearance was observed even in an accelerated exposure test of 1000 hours.

[Table] Example 2 Methyl methacrylate monomer containing 0.055% diisopropyl peroxydicarbonate was heated at 60°C using a jacketed single tube in a stirred tank reactor equipped with the ribbon-shaped stirring blade used in Example 1. The reactor was preheated to 100% and fed continuously so that the average residence time in the tank reactor was 4.6 minutes. Reactor temperature
Stirring was carried out at 130° C. at a speed of 800 revolutions/min and the pressure was maintained at 2.5 atmospheres gauge. The syrup exiting the reactor is rapidly cooled to a polymerization rate of 25% at 25°C.
A syrup with a viscosity of 9.7 poise was obtained. The number average degree of polymerization of the polymer in the syrup is 700, the weight average degree of polymerization is 1435, and the polydispersity of the polymerization degree distribution is therefore 2.05. A polymerizable liquid composition is prepared by mixing and dissolving an appropriate amount of cumyl peroxyneodecanoate as a polymerization initiator and an appropriate amount of tetraethylene glycol dimethacrylate as a polyfunctional unsaturated monomer in this syrup and degassing under reduced pressure. In the same manner as in Example 1, the mixture was injected into a polymerization mold for a flat plate, impregnated into glass fibers, and polymerized and cured to obtain a second result.

[Table] No polymer foaming was observed in any of the obtained resin plates with a thickness of approximately 1 mm, despite the extremely short polymerization time.
Crazing resistance was also good. moreover
No change in appearance was observed even after 1000 hours of accelerated exposure test. Example 3 Methyl methacrylate and methacrylic resin (trade name Sumipex-B MH, Sumitomo Chemical Co., Ltd.)
When dissolved at 20%, the viscosity at 25°C was 1 poise. The number average degree of polymerization of the polymer in the syrup is 680, the weight average degree of polymerization is 1428,
Therefore, the polydispersity of the polymerization degree distribution is 2.1. To this syrup, 0.26% of isopropylcumyl peroxyneodecanoate (0.74 x 10 ^-3 parts by mole per 100 parts by weight of the syrup) was added as a polymerization initiator.
A polymerizable liquid composition prepared by mixing and dissolving 2.5% of trimethylolpropane triacrylate as a polyfunctional unsaturated monomer and degassing under reduced pressure was poured into a polymerization mold for a flat plate in the same manner as in Example 1 to form glass fibers. was impregnated with water and polymerized and cured in a heating bath at 85°C. The polymerization curing time at this time was 7.5 minutes, which was a very short time. The obtained resin plate with a thickness of about 0.7 mm showed no polymerization foaming despite the short polymerization time, and also had good crazing resistance. Furthermore, no change in appearance was observed even in an accelerated exposure test of 1000 hours. Further, the bending strength was 1670 Kg/cm ² , which was sufficient. Example 4 To the syrup obtained in Example 1, 0.15% of a 70% toluene solution of isopropyl cumyl peroxy neodecanoate as a polymerization initiator (0.30 x 10 ^-3 parts by mole of neodecanoate per 100 parts by weight of the syrup) was added. ) and 0.7% of divinylbenzene as a polyfunctional unsaturated monomer were mixed and dissolved and degassed under reduced pressure to form a polymerizable liquid composition, which was poured into a polymerization mold for a flat plate in the same manner as in Example 1 to form a glass fiber. It was impregnated and polymerized and cured in a heating bath at 80°C. The polymerization and curing time at this time was 12.5 minutes, which was a very short time. The resulting resin plate with a thickness of about 1 mm showed no polymerization foaming despite the short polymerization period, and also had good craze resistance. Furthermore, no change in appearance was observed even in an accelerated exposure test of 1000 hours. Reference Example 1 Adding 0.18% of a 70% mineral spirit solution of cumyl peroxyneodecanoate as a polymerization initiator to the syrup of Example 2 (0.41 x 10 ^-3 parts by mole of neodecanoate per 100 parts by weight of the syrup)
Example 1
In the same manner as above, it was poured into a flat plate polymerization mold to impregnate glass fibers, and polymerized and cured in a heating bath at 98°C. The polymerization curing time at this time was 11.5 minutes, which was a very short time. However, polymerization foaming was observed in the obtained resin plate with a thickness of about 1 mm, and even if the amount of polymerization initiator is appropriate, polymerization foaming occurs when the heating curing temperature exceeds the range of the present invention. Undesirable. Reference Example 2 Polymerization was carried out by mixing and dissolving an appropriate amount of cumyl peroxyneodecanoate as a polymerization initiator and 1.2% of ethylene glycol dimethacrylate as a polyfunctional unsaturated monomer in the syrup of Example 2, and degassing under reduced pressure. In the same manner as in Example 1, the liquid composition was injected into a polymerization mold for a flat plate, impregnated into glass fibers, and polymerized and cured to obtain the results shown in Table 3.

[Table] No polymeric foaming was observed in any of the obtained resin plates with a thickness of about 1 mm. However, from Table 3, when the amount of polymerization initiator is less than the range of the present invention, or even when the amount of polymerization initiator is appropriate but the heating curing temperature is lower than the range of the present invention, the polymerization curing time is longer. This is not preferable because productivity decreases over time. Reference example 3 Methyl methacrylate and methacrylic resin (product name Sumipex-B MH, Sumitomo Chemical Co., Ltd.)
A 50% dibutyl phthalate solution of isopropyl cumyl peroxyneodecanoate as a polymerization initiator was added to a syrup containing 10% of 10% dibutyl phthalate (0.56% solution of isopropyl cumyl peroxyneodecanoate per 100 parts by weight of the syrup).
x 10 ^-3 mol parts) and 0.8% ethylene glycol dimethacrylate as a polyfunctional unsaturated monomer were mixed and dissolved and degassed under reduced pressure. It was injected into a mold to impregnate glass fibers, and polymerized and cured in a heating bath at 80°C. The polymerization and curing time at this time was 19.0 minutes. The obtained resin plate with a thickness of about 1 mm is polymerized and foamed, and even if the amount of polymerization initiator is appropriate, if the polymerization rate of the syrup is low, the polymerization curing time becomes long and polymerization and foaming occurs, which is not preferable. Reference Example 4 In Example 3, the polymerizable liquid composition except for trimethylolpropane triacrylate, which is a polyfunctional unsaturated monomer, was polymerized and cured in the same manner as in Example 3. When the obtained resin plate with a thickness of about 0.7 mm was immersed in ethyl acetate for 10 minutes, numerous crazes appeared on its surface. On the other hand, when the bending strength of the obtained resin plate was measured, it was as low as 1280 Kg/cm ² . When an accelerated exposure test was further conducted for 100 hours, the resin plate turned white. Reference Example 5 The same stirred tank reactor as in Example 1 was used, except that methyl methacrylate monomer containing 0.12% azobisdimethylvaleronitrile was continuously fed so that the average residence time was 2.9 minutes. Prepolymerization was carried out in the same manner as in Example 1, and the number average degree of polymerization of the polymer in the syrup having a polymerization rate of 30% and a viscosity of 8 poise at 25°C was 450, and a weight average degree of polymerization of 945. Therefore, the polydispersity of the polymerization degree distribution is 2.1. This syrup contains 0.08% cumyl peroxyneodecanoate as a polymerization initiator (0.26 x 10 ^-3 parts by mole per 100 parts by weight of the syrup) and 0.5% ethylene glycol dimethacrylate as a polyfunctional unsaturated monomer. A polymerizable liquid composition prepared by mixing and dissolving and degassing under reduced pressure was injected into a flat polymerization mold to impregnate glass fibers in the same manner as in Example 1, and polymerized and cured in a heating bath at 70°C. The polymerization and curing time at this time was 14.0 minutes, which was a very short time. Although no polymeric foaming was observed in the obtained resin plate with a thickness of about 1 mm, when the resin plate was immersed in ethyl acetate for 10 minutes, numerous crazes were generated on its surface. On the other hand, when the bending strength of the obtained resin plate was measured, it was as low as 1240 Kg/cm ² .

[Brief explanation of the drawing]

Figure 1 shows cumyl peroxyneodecanoate or/and
and is a graph showing the relationship between the molar parts of monoalkyl cumyl peroxyneodecanoate and heat curing temperature.

Claims (1)

[Scope of Claims] 1. A syrup containing methyl methacrylate as a main component and a polyfunctional unsaturated monomer having two or more unsaturated groups with a polymerization rate of 15 to 35% by weight, and cumylpere as a polymerization initiator. Glass fibers are impregnated with or mixed with a polymerizable liquid composition in which oxyneodecanoate or/and monoalkyl cumyl peroxyneodecanoate is dissolved, and then heated and cured,
In this case, the relationship between the number of mole parts of cumyl peroxyneodecanoate and/or monoalkyl cumyl peroxyneodecanoate based on 100 parts by weight of the syrup and the heat curing temperature (°C) as a polymerization initiator is shown in Figure 1. A (1×10 ^-4 , 90), B (1×
10 ^-2 , 85), C (3 × 10 ^-2 , 60), D (1 × 10 ^-4 ,
65) A method for producing a glass fiber-reinforced resin board, characterized by polymerizing and curing it under conditions within a closed region formed by connecting each point of 65) with a straight line. 2 The number average degree of polymerization in the syrup is 500 or more, the weight average degree of polymerization is 2500 or less, and the polydispersity of the polymerization degree distribution expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization of the polymer is 2.5. A method according to claim 1, characterized in that: 3 The polyfunctional unsaturated monomer having two or more unsaturated groups contained in the syrup is ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate,
decamethylene glycol diacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, allyl acrylate, crotyl acrylate, mesaryl acrylate, tetramethylolmethane triacrylate,
Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, decamethylene glycol dimethacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, crotyl methacrylate, mesaryl methacrylate, Tetramethylolmethane trimethacrylate, divinylbenzene, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallylbenzene, diethylene glycol bisallyl carbonate, diallyl maleate, diallyl fumarate, diallyl itaconate, divinyl ether, dimesalyl ether 2. The method according to claim 1, wherein the amount is 0.2 to 10% by weight based on the total weight of the syrup. 4 Monoalkyl cumyl peroxy neodecanoate, which is a polymerization initiator, is isopropyl cumyl peroxy neodecanoate, n-butyl cumyl peroxy neodecanoate, isobutyl cumyl peroxy neodecanoate, sec-butyl cumyl peroxy selected from neodecanoate, tert-butylcumyl peroxyneodecanoate, 2-ethylhexylcumyl peroxyneodecanoate, ethoxycumyl peroxyneodecanoate, 3-methoxybutylcumyl peroxyneodecanoate 2. The method according to claim 1, wherein the method is at least one type.