JPS60245641A - Highly transparent, flame-retardant fiber-reinforced plastic product - Google Patents

Abstract

PURPOSE:The titled product having excellent stain resistance without deteriorating the transparency, obtained by impregnating a specified fibrous reinforcement with a resin composition comprising a methyl methacrylate precondensate syrup and alumina white, followed by solidifying thereof. CONSTITUTION:At least 10pts.wt. fibrous reinforcement (e.g. B glass), having a refractive index of 1.51 + or -0.03 (15 deg.C) and a length of 10mm. or longer is impregnated with 100pts.wt. resin composition, which is prepared by kneading 100pts.wt. methyl methacrylate precondensate syrup (a), obtained by dissolving polymethyl methacrylate in methyl methacrylate monomer in an amount to give a required viscosity, and at least 30pts.wt. alumina white (b) of the formula, having a refractive index of 1.47-1.56 (at room temperatures), being an amorphous compound by X-ray diffractometry, followed by addion of 0.1-5pts.wt. curing agent (e.g. benzoyl peroxide) thereto. Then, the resin composition is solidified into one piece together with the reinforcement, giving the titled plastic product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fiber-reinforced plastic article based on volume Φ methyl methacrylate, which is flame retardant and highly transparent. An article made by impregnating methyl methacrylate prepolymer syrup into a reinforcing glass fiber product made of B glass, which has a refractive index in the range of 1.51 ± 0.02 at 15°C, and solidifying it as one piece.
It is widely used as corrugated plates and flat plates with excellent translucency, but it is flammable. Various methods have been proposed to make this flame retardant. For example, as a method that does not generate toxic gas,
A method by addition of aluminum hydroxide is also known. However, although some transparency can be expected with the addition of aluminum hydroxide, whitening is significant. ' The present inventors conducted various studies to solve the above problems, and as a result, the general formula [Al 2SO4(OH) a・XHx
O.2Al(OH)3). By using alumina white shown in #1 with a specific fibrous reinforcing material, #1 flame-retardant polymethyl methacrylate fiber reinforcement with almost no loss of translucency and excellent stain resistance is achieved. The present invention was completed by discovering that plastic articles can be obtained.

That is, in the present invention, a resin composition consisting of 30 parts by weight or more of alumina white represented by the general formula % and a curing agent is mixed with 100 parts by weight of a methyl methacrylate prepolymer syrup at 15°C. When the refractive index falls to 1.
The present invention provides a transparent flame-retardant fiber-reinforced plastic article obtained by impregnating a fibrous reinforcing material in the range of 51±0.03 and solidifying it as one piece.

The methyl methacrylate prepolymer syrup that can be used in the present invention can be prepared by dissolving enough polymethyl methacrylate to give the methyl methacrylate monomer the necessary viscosity, or by adding a polymerization initiator and a chain transfer agent to the methyl methacrylate monomer. Polymerization is carried out by heating, and when the desired polymerization rate is reached, the reaction system is rapidly cooled by adding cold methyl methacrylate monomer containing a polymerization terminator to stop the polymerization. It is. Incidentally, in order to improve rather than reduce the physical properties of the methyl methacrylate polymer, partial use of other copolymerization monomers or some use of crosslinking monomers may naturally be applied to the methyl methacrylate-based preliminary used in the present invention. Included in polymer syrup.

Copolymerization monomers include styrene, inbutyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, and crosslinking monomers include trimethylolpronotrimethacrylate, hydrogenated bisphenol A diacrylate, etc. Acid, known monomers, especially acrylates and methacrylates are preferred.

Alumina white is represented by the above general formula and has a refractive index of about 1.47 to 1.56 at room temperature, but is an amorphous compound according to X-ray diffraction.

In the present invention, the refractive index is preferably 1.47 to 1.54 at room temperature. If a substance within this range is used, the resulting article will have particularly excellent translucency. The most preferable refractive index is 1
．． The range is 51±0.02.

The ratio of the methyl methacrylate prepolymer syrup to alumina white is 100 parts by weight for the former and 30 parts by weight or more for the latter. If the amount of alumina white is less than 30 parts by weight, the flame resistance will be insufficient, so it is preferable to use as much as possible for molding workability.

Curing agents include polymerization initiators such as organic peroxides and diazo compounds. A combination system of an organic peroxide and an accelerator is particularly effective when curing at medium to low temperatures. Organic peroxides include penzoyl peroxide, lauroyl peroxide,
Diazo compounds such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, and cyclohexanone peroxide include 2,2'-azopisisobutyroni), 2,2'-azobis(2,4-dimethylpaleonitrile L2, Examples include 2'-azobis(4-methylbaleonitrile L) and 1'-azobis(cyclohexane-1-carbonitrile), and accelerators include tertiary amines, quaternary ammonium salts, cobalt, manganese, copper, calcium, etc. soluble metal soaps,
Can be used alone or in combination.

The fibrous reinforcement material has a refractive index of 1.51± at 15°C.
Any material, organic or inorganic, can be used as long as it is within the range of 0.03, but particularly preferred is 10 parts by weight with a refractive index of 1.51±0.02 parts by weight at 15°C. The above is preferable, and the fiber length is also preferably 10 cu or more. This is to maintain the properties of fiber-reinforced plastics such as impact resistance of the product.

Representative embodiments of the invention are as follows.

30 parts by weight or more of the above-mentioned alumina white is kneaded with 100 parts by weight of the methyl methacrylate prepolymer syrup, and then the above-mentioned curing agent is added in a proportion of 0.1 to 560 parts by weight, and if necessary, the above-mentioned curing agent is added. An accelerator is also added to prepare a resin composition. This resin composition is defoamed if necessary, and impregnated into mats or fabrics of the above-mentioned fibrous reinforcing material, as well as preformed rovings or roving chops, and then processed by the usual fiber-reinforced plastics molding method. The purpose can be achieved by molding and curing. For example, the fibrous reinforcing material in the form of a mat is continuously supplied, sandwiched between release films together with the resin composition, impregnated while defoaming, and guided to a curing furnace to form a corrugated shape and solidify. This makes it possible to continuously produce transparent, flame-retardant fiber-reinforced plastic corrugated sheets with excellent weather resistance. Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples, but these do not include all of the present invention.

Example 1 Methyl methacrylate 14 and 9 were heated and the temperature was raised to 85° C. for 30 minutes, during which time the atmosphere was replaced with N2 gas to remove oxygen. When the temperature reached 85℃, thioglycolic acid 8
02 was added, followed by azobisisobutyronitrile 69 to start polymerization, and the internal temperature was increased to 90°C at a rate of 1°C to 1.5°C/min.
The temperature was raised to ℃, kept as it was, and after 50 minutes had passed after adding the initiator, 5 Kq of methyl methacrylate (methyl methacrylate) was added over 2 minutes, cooled to stop the polymerization, and the non-volatile content was reduced to 24.
A methyl methacrylate prepolymer syrup with a viscosity of 130 centivoids was obtained. Lauryltrimethylammonium chloride (concentration approximately 60 centivoids) dissolved in impropatul was added to this syrup I N9.
%) 107 and stir well, then add cumyl hydroperoxide (concentration approximately 80 parts) 10? was added and dissolved well. Alumina white (
6 oor (manufactured by Ozeki Chemical Industry Co., Ltd.) was added, mixed well, and degassed to obtain a composition (1). The composition (1
) and B glass fibers (manufactured by Nippon Electric Glass Co., Ltd.) cut into 1-inch lengths were sprinkled as uniformly as possible in amounts of 8002 and 2002 per 1 m2 of glass plate, and then defoamed. The above composition (1) and the composition (l1200f
I posted it. Next, the composition (1) and the B glass fiber were pressed down with the other glass plate, being careful not to introduce air bubbles, and the excess composition (1) that was not used for impregnating the B glass fiber was removed.

Thereafter, it was cured at room temperature for 15 hours, and then further cured at 80° C. for 2 hours to obtain a fiber-reinforced glass board (1) with a thickness of 1.9 van. Fiber reinforced plastic board (1
) was flame retardant and transparent enough to make it possible to read a newspaper attached closely to the back.

Comparative Example 1 A comparative fiber-reinforced plastic board (1) was obtained in the same manner as in Example 1 except that aluminum hydroxide 6009 was used instead of alumina white (manufactured by Daibiki Kagaku Kogyo Co., Ltd.) 6ooy in Example 1. . Although the comparative fiber-reinforced plastic board (]) was flame-retardant, it was inferior to the fiber-reinforced plastic board (1>) and was milky white, making it impossible to read a newspaper that was placed closely against the back.

Example 2 The same methyl methacrylate prepolymer syrup obtained in Example 1]0OOfI, benzoyl peroxide 57, alumina white (manufactured by Ozeki Chemical Industry Co., Ltd.) 2oo
Composition (2) was obtained by kneading B glass fibers 300S+ cut into lengths of 1/4 inch and 1/4 inch in a kneader until uniform. Next, the composition (2) was filled and pressed into a mold for a flat plate, heated at 80°C for 90 minutes, and made into a fiber-reinforced plastic plate with a thickness of 2.3 mm.
2) was obtained. The fiber-reinforced plastic board (2) was flame-retardant and transparent enough to read a newspaper that was closely attached to the back.

Example 3 Add 3 liters of azobisisobutyronitrile to 1000 r of the same methyl metasupralylate prepolymer syrup obtained in Example 1.
3 oor of alumina white (manufactured by Ozeki Chemical Industry Co., Ltd.) was thoroughly mixed to obtain a composition (3).

Using composition (3) and B glass roving,
The helmet was molded according to the pre-7 ohm mated metal die method practiced in the unsaturated polyester resin industry. The obtained helmet was flame retardant and had excellent transparency.

Claims (1)

[Claims] 1. Methyl methacrylate prepolymer syrup and general formula [AlzSO4(OH)<・XH2O・2Al
(OH)s]. A resin composition in which the alumina white shown in
A highly transparent flame-retardant fiber-reinforced plastic article obtained by impregnating a fibrous reinforcing material in a range of 0.03 and solidifying it as one piece.