JPH0678381B2 - Method for producing flame-retardant acrylic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a flame-retardant acrylic resin having high flame retardancy and excellent physical properties. This flame-retardant acrylic resin is excellent in weather resistance, transparency and mechanical strength, which are the characteristics of the acrylic resin, and is useful as a building material or the like that requires flame retardancy.

[Conventional technology and problems]

The acrylic resin is a thermoplastic resin whose main component is methyl methacrylate. This resin has high mechanical strength,
It has excellent water and weather resistance, good surface gloss, and is superior in transparency compared to other resins, and is easy to mold and process. It is used for vehicle window glass, electric lamp covers, motorcycle cowling glass fiber reinforced plates, Used for kitchen counters and washbasins. Further, in recent years, the fields of application thereof are expanding to laser disks, optical fibers and the like.

However, the acrylic resin has not been put to practical use as a building material or the like that requires flame retardancy while having the above-mentioned characteristics.

Conventionally, as a method of imparting flame retardancy to acrylic resins and the like, it has been known to add a large amount of organic halogen compounds or organic phosphorus compounds (for example, Konishi, Hirao, “Flame Retardant”, Nos. 89-90). Pp. 106, koushobou (197
2) described).

Generally, adding a large amount of an organic halogen compound or an organic phosphorus compound reduces the weather resistance, which is a characteristic of acrylic resin, and turns the molded product yellow, or plasticizes the acrylic resin, or has a crazing resistance and mechanical properties. However, it has a drawback in that the transparency is deteriorated and the transparency is particularly impaired.

[Means for solving problems]

The inventors of the present invention have earnestly focused on the development of an acrylic resin having flame retardancy while maintaining the weather resistance, transparency and mechanical strength, which are the characteristics of the acrylic resin containing methyl methacrylate as a main component. The present invention has been reached.

That is, the present invention provides (1) a copolymer of methyl methacrylate and a monomer having a hydroxyl group in the molecule and having an ethylenically unsaturated bond,
A method for producing a flame-retardant acrylic resin characterized by reacting a halogenated aromatic acid anhydride, and (2) Methyl methacrylate and a monomer having a hydroxyl group in the molecule and an ethylenically unsaturated bond A method for producing a flame-retardant acrylic resin, which comprises reacting a halogenated aromatic acid anhydride with a partial copolymer with the body and then performing post-polymerization.

Hereinafter, the method of the present invention will be described in detail.

The amount of methyl methacrylate used in the present invention is 20% by weight or more in the flame-retardant acrylic resin. If it is less than 20% by weight, the weather resistance, surface gloss, mechanical strength, etc., which are characteristics of the acrylic resin, are deteriorated.

Further, as the partial copolymer or a monomer having an ethylenically unsaturated bond having a hydroxyl group in the molecule to be copolymerized,
For example, 2-hydroxyethyl methacrylate, methacrylic acid
2-hydroxypropyl, neopentyl glycol methacrylate, trimethylolpropane methacrylate, polyethylene glycol methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, neopentyl glycol acrylate, trimethylolpropane acrylate, acrylic acid Examples thereof include polyethylene glycol. The amount of the monomer having an ethylenically unsaturated bond having a hydroxyl group in the molecule is equal to or more than the equivalent amount of the halogenated aromatic acid anhydride described below, and if it is less than this, unreacted halogenated aromatic acid anhydride is It remains and the weather resistance and water resistance are deteriorated.

If necessary, other monomers may be used in combination. Other monomers include, for example, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, vinyl acetate, styrene, 2-methylstyrene, chlorostyrene, t-butylstyrene, vinyl versatate, ethylene. Glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, divinylbenzene, triallyl isocyanate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, ethylene glycol diacrylate, trimethylol propane triacrylate, Fumaric acid butyl ester, stearyl methacrylate, decyl methacrylate Dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, triethylene glycol dimethacrylate, t- butyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, 1,3-butanediol methacrylate, isodecyl methacrylate, and the like. Furthermore, a monomer containing phosphorus can also be used. Particularly, the flame retardancy can be further improved without impairing the object of the present invention by partially copolymerizing or copolymerizing the phosphorus-containing monomer within the range of 0.1 to 3% by weight. Examples of the phosphorus-containing monomer include methacryloxyethyl phosphate, bis (methacryloxyethyl) phosphate, methacryloxypropyl phosphate, 1-chloromethyl-2-methacryloxyethyl phosphate, diphenyl Examples include 2-methacryloethyl phosphate, dibutyl-2-methacryloxyethyl phosphate, dioctyl-2-methacryloxyethyl phosphate, and bis (2-chloroethyl) vinyl phosphate.

Further, the total amount of methyl methacrylate, a monomer having a hydroxyl group in the molecule and having an ethylenically unsaturated bond, and other monomers used as necessary is 40% by weight in the obtained flame-retardant acrylic resin. It should be at least%.

Regarding the method for partial copolymerization or copolymerization of the methyl methacrylate of the present invention with a monomer having a hydroxyl group in the molecule and having an ethylenically unsaturated bond, and other monomer used as necessary Is not particularly limited, a conventional polymerization method,
That is, bulk polymerization (including cast polymerization), suspension polymerization,
It can be carried out by emulsion polymerization or solution polymerization. In the case of partial copolymerization, the polymerization rate is usually 20% or more. It is preferably 20 to 40%.

Examples of the halogenated aromatic acid anhydride used in the present invention include 4,6-dichlorophthalic anhydride, 4,5,6-trichlorophthalic anhydride, 4,5,7-trichlorophthalic anhydride, 4,5, and 6,7-tetrachlorophthalic anhydride, 4,6-dibromophthalic anhydride,
4,5,6-Tribromophthalic anhydride, 4,5,7-Tribromophthalic anhydride, 4,5,6,7-Tetrabromophthalic anhydride, 4,5,6,
Examples thereof include 7-tetraiodophthalic anhydride, 4,5,6,7-tetrafluorophthalic anhydride, and het anhydride.

In the reaction of the partial copolymer or copolymer obtained by the above-mentioned polymerization method and a halogenated aromatic acid anhydride,
The amount of the halogenated aromatic acid anhydride used in the flame-retardant acrylic resin is preferably 1 to 40% by weight, more preferably 5 to
35% by weight. If it is less than 1% by weight, it is not sufficient to impart flame retardancy, and if it exceeds 40% by weight, the original properties of the acrylic resin are impaired, which is not preferable.

The reaction temperature is 50 to 110 ° C., and the reaction time is 1 to 5 hours. Also, since polymerization may be promoted during the reaction,
It is necessary to prevent the resin from thickening by adding a polymerization inhibitor or air bubbling.

This reaction is an esterification reaction and is easy to operate. When the partial copolymer is used, the product obtained by the reaction is a prepolymer of a non-viscous acrylic resin. Therefore, the desired resin can be obtained by postpolymerization by a known method. When a copolymer is used, the desired resin can be obtained directly.

〔Example〕

The method of the present invention will be described in more detail with reference to the following examples.

Example 1 A flask equipped with a thermometer and a stirrer was charged with 400 g of methyl methacrylate, 100 g of styrene, and 150 g of 2-hydroxyethyl methacrylate, a chain transfer agent of 2 g thioglycolic acid, and a polymerization initiator of azobisisobutyronitrile 0.0065 g. Add 1
After copolymerization at 00 ℃ for 8-10 hours, polymerization inhibitor 2,4-
Add 0.0195 g of dimethyl-6-t-butylphenol,
A partial copolymer having a viscosity of 1 poise and a polymerization rate of 25% was obtained.

Next, 350 g of hetonic anhydride was added to this partial copolymer,
After reacting at 70 ° C. for 2 hours, the mixture was cooled to obtain a prepolymer having a viscosity of 3.5 poise.

Then, 1 g of the polymerization initiator t-butyl peroxyneodecanate was added to 100 g of the obtained prepolymer, and after stirring and mixing,
With a glass mold coated with a commercial release agent, 60 ° C x 1 hour,
Further, cast polymerization was carried out at 120 ° C. for 30 minutes to obtain a refractory acrylic plate. The molded plate was measured for oxygen index according to JIS K-7206 Oxygen index method for flame-retardant test of polymeric materials and subjected to bending test according to JIS K-7203.

The method of evaluating transparency was performed using a spectroscopic color difference meter.

Examples 2 to 4 Table 1 shows a monomer having methyl methacrylate as a main component and a monomer having a hydroxyl group in the molecule and having an ethylenically unsaturated bond, in the same apparatus as in Example 1. The mixture was charged in such a ratio and copolymerized in the same manner as in Example 1. The viscosity was 1 poise, and the polymerization rate was 25% in Example 2 and 2 in Examples 3 and 4.
A 0% partial copolymer was obtained.

Further, a halogenated aromatic acid anhydride was added to this partial copolymer at a ratio as shown in Table 1, reacted at 70 ° C. for about 2 hours, and then cooled to obtain a preliminary viscosity of 3 to 5 poises. A polymer was obtained. The prepolymers were cast-polymerized in the same manner as in Example 1, and the obtained flame-retardant acrylic plate was evaluated in the same manner as in Example 1.

Examples 5 to 8 A device similar to that of Example 1 was used, containing a monomer containing methyl methacrylate as a main component, a monomer having a hydroxyl group in the molecule and an ethylenically unsaturated bond, and phosphorus. As a monomer to be used, bis (2-chloroethyl) vinyl phosphate was charged at a ratio shown in Table 1, and copolymerized in the same manner as in Example 1 to obtain a partial copolymer having a viscosity of 1 poise and a polymerization rate of 25%. I got a thing. The resulting partial copolymer was reacted with a halogenated aromatic acid anhydride to obtain a prepolymer having a viscosity of 3 to 5 poise. The prepolymers were cast-polymerized in the same manner as in Example 1, and the obtained flame-retardant acrylic plate was evaluated in the same manner as in Example 1.

Comparative Example 1 750 g of methyl methacrylate, 100 g of styrene and 150 g of 2-hydroxyethyl methacrylate were placed in the same apparatus as in Example 1.
Were charged and copolymerized in the same manner as in Example 1 to obtain a partial copolymer having a viscosity of 1 poise and a polymerization rate of 25%. This partial copolymer was cast-polymerized in the same manner as in Example 1, and the obtained resin was evaluated in the same manner as in Example 1.

Comparative Example 2 A device similar to that of Example 1 was charged with 550 g of methyl methacrylate and 100 g of styrene and copolymerized in the same manner as in Example 1 to obtain a partial copolymer having a viscosity of 1 poise and a polymerization rate of 25%. It was To the obtained partial copolymer, 350 g of anhydrous head was added to obtain a prepolymer having a viscosity of 3 poise. The prepolymer was cast-polymerized in the same manner as in Example 1, and the obtained molded plate was evaluated in the same manner as in Example 1.

Example 9 The same apparatus as in Example 1 was charged with 3000 g of distilled water, 10 g of polyvinyl alcohol was dissolved as a suspension stabilizer, 600 g of methyl methacrylate and 100 g of 2-hydroxyl ethyl methacrylate were added, and the polymerization initiator peroxide was added. 2 g of benzoyl oxide was added and polymerization was carried out at 80 ° C. for 10 hours. Further, 300 g of het anhydride was added and the reaction was carried out for 3 hours. The obtained resin was washed by a conventional method and dehydrated and dried to obtain a plate-shaped molded product.

The molded plate thus obtained was evaluated in the same manner as in Example 1.

The above results are shown in Table 1.

The symbols in Table 1 are as follows.

(Meth) acrylic acid hydroxy ester A: 2-hydroxyethyl methacrylate B: 〃 2-hydroxypropyl C: 2-hydroxyethyl acrylate D: 〃 2-hydroxypropyl halogenated aromatic acid anhydride I: Het anhydride II : 4,5,6,7-Tetrachlorophthalic anhydride III: 4,5,6,7-Tetrabromophthalic anhydride IV: 4,5,6,7-Tetrafluorophthalic anhydride [Effects of the Invention] The flame-retardant acrylic resin composition of the present invention has good stability,
It is possible to provide a molded product having excellent heat resistance and flame retardancy without impairing the original transparency of the acrylic resin and without lowering the mechanical strength.

Claims (2)

[Claims] 1. A difficulty characterized by reacting a halogenated aromatic acid anhydride with a copolymer of methyl methacrylate and a monomer having a hydroxyl group in the molecule and having an ethylenically unsaturated bond. Method for producing flammable acrylic resin. 2. A halogenated aromatic acid anhydride is reacted with a partial copolymer of methyl methacrylate and a monomer having a hydroxyl group in the molecule and having an ethylenically unsaturated bond, and then post-polymerized. A method for producing a flame-retardant acrylic resin, characterized by: