JPH0689202B2 - Flame-retardant styrene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a novel flame-retardant styrene resin composition. More specifically, the present invention is suitable as a material for OA equipment, home appliances, automobile parts, and the like, has high impact strength, has excellent gloss and rigidity, and has excellent flame retardancy. The present invention relates to a flame-retardant styrene resin composition having an excellent balance of physical properties.

[Prior Art] Rubber-modified styrene resin compositions are widely used for various purposes because they are excellent in impact resistance and rigidity and have good moldability. Further, it is known to add a flame retardant and a flame retardant aid to impart flame retardancy to the rubber-modified styrene resin composition.

Conventionally, this rubber-modified styrenic resin composition has been prepared by blending a styrene-based polymer with a rubber-like polymer, or by polymerizing a styrene-based monomer in the presence of the rubber-like polymer. A part of the styrene-based monomer is graft-polymerized into the coalescence, and the rest of the styrene becomes a styrene-based polymer, so that a substantially rubber-like polymer / styrene-based monomer graft copolymer and styrene-based polymer are obtained. Are manufactured by a method in which a mixed state of.

However, in such a rubber-modified styrenic resin composition, the rubber-like polymer is dispersed only in the rubber component in the form of particles or a salami structure, and there is a drawback that the gloss is poor, and the gloss and impact resistance are low. A flame-retardant styrene-based resin composition having excellent properties and rigidity has not been obtained.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of the conventional flame-retardant styrene resin composition, has high impact strength, and has excellent gloss and rigidity. The purpose of the present invention is to provide a flame-retardant styrene resin composition having an excellent balance of physical properties.

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to develop a flame-retardant resin composition having an excellent balance of physical properties such as impact resistance, gloss, and rigidity, and as a result, have found that the dispersed rubber form is It has been found that an occlusion structure can meet the above purpose, and the present invention has been completed based on this finding.

That is, the present invention relates to (a) 100 parts by weight of a rubber-modified styrenic resin composition comprising a styrene polymer and a rubbery polymer, (b) 3 to 40 parts by weight of a flame retardant, and (c) a flame retardant auxiliary 1 to
A composition containing 15 parts by weight, and (a)
The rubber-like polymer in the component includes styrene-butadiene block copolymer rubber and polybutadiene rubber in the former /
The latter is blended in a ratio of 10/0 to 6/4 (weight ratio), the area average particle diameter (diameter) is 0.4 to 0.6 μm, and the dispersed rubber form is in one rubber particle. 70% or more of the occlusion structure in which the core is a styrenic polymer and the shell contains 5 or less inclusion occlusions made of a rubbery polymer, and at least 50% or more of them include one inclusion occlusion. The present invention provides a flame-retardant styrenic resin composition characterized by having.

Hereinafter, the present invention will be described in detail.

The rubber-modified styrene resin composition of component (a) in the flame-retardant composition of the present invention is required to have an occlusion structure in the dispersed rubber form.

If the dispersed rubber form does not have an occlusion structure, it will be inferior in impact resistance and gloss.

Here, the occlusion structure means that in one rubber particle,
A structure in which the core is a styrenic polymer and the shell contains 5 or less inclusion occlusions made of a rubbery polymer, and at least 50% or more of the inclusion occlusions are 1 inclusion occlusion.

In the present invention, the occlusion structure as described above is used.
% Or more, and particles such as salami structure
If 30% or more is mixed, good gloss may not be obtained.

The rubber-modified styrene-based resin composition as the component (a) comprises a styrene-based polymer and a rubber-like polymer.

The styrene-based polymer may be a styrene homopolymer or a copolymer of styrene and a monomer copolymerizable with styrene. Examples of the copolymerizable monomer include α-methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, pt-butylstyrene and α.
Examples thereof include aromatic monovinyl compounds such as -methyl-p-methylstyrene and vinylnaphthalene, acrylonitrile, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, maleic anhydride, and phenylmaleimide. These monomers may be used alone or in combination of two or more, but usually 50% by weight or less, preferably 40% by weight or less based on all monomers containing styrene. Used in proportion.

On the other hand, as the rubber-like polymer, water lily-butadiene-based block copolymer rubber and polybutadiene rubber are used, the former / latter = 10/0 to 6/4 (weight ratio), preferably 1
A mixture of 0/0 to 6.5 / 3.5 (weight ratio) is used.

As the styrene-butadiene block copolymer rubber, the molecular weight is in the range of 50,000 to 500,000, and the content of the polymer block formed of styrenes is 10 to 60.
Those in the range of wt% are particularly preferable. The molecular weight is 5
If it is less than 0,000, the impact resistance is not sufficient and 500,0
When it exceeds 00, the fluidity at the time of molding is deteriorated, which is not preferable. If the content of the polymer block formed by styrenes is less than 10% by weight, the gloss is inferior.
If the content exceeds 100% by weight, the impact resistance tends to decrease.
In addition, a polybutadiene rubber having a molecular weight of about 50,000 to 1,000,000 may be appropriately mixed and used with the styrene-butadiene block copolymer rubber.

The molecular weight of this rubber-like polymer is the weight average molecular weight in terms of polystyrene by GPC.

The rubber-like polymer has an occlusion structure and has an area average particle diameter (diameter) of 0.4 to 0.6 μm, and a ratio of the area average particle diameter to the number average particle diameter (diameter) is 1.0 to 2.5, preferably 1.0. It is preferable that the particles having a particle size of about 1.8 are dispersed in the styrene polymer as the component (A).

If the area average particle size is less than 0.4 μm, the impact resistance is not sufficient, and if it exceeds 0.6 μm, the gloss tends to decrease. Further, the area average particle diameter is 2.
If it exceeds 5, the gloss tends to decrease.

The styrene-based polymer and the rubber-like polymer are preferably contained in the proportions of 70 to 92% by weight and 30 to 8% by weight, respectively, preferably 72 to 90% by weight and 28 to 10% by weight. is there. If the content of the rubber-like polymer is less than 8% by weight, the impact resistance improving effect tends to be insufficiently exerted, resulting in 30% by weight.
If it exceeds, gloss and fluidity tend to decrease.

The rubber-modified styrenic resin composition as the component (a) can be produced by blending a styrenic polymer and a rubber-like polymer, but is copolymerized with styrene or styrene in the presence of the rubber-like polymer. It is preferably prepared by polymerizing with possible monomers.

Next, one example of a preferred method for producing the resin composition of the present invention by the bulk-suspension two-step polymerization method will be described. First, styrene or a mixture of styrene and a monomer copolymerizable with styrene,
A rubbery polymer is added and heated as necessary to dissolve. It is preferable that this dissolution be performed as uniformly as possible.

Next, to this solution, a molecular weight regulator (chain transfer agent) such as alkyl mercaptan and a polymerization initiator such as an organic peroxide used as necessary are added, while heating to a temperature of about 70 to 150 ° C., Preliminary polymerization by bulk polymerization is carried out with stirring until the degree of polymerization reaches 10 to 60%. In this prepolymerization step, the rubbery polymer is dispersed into particles by stirring.

Then, the prepolymerized solution is suspended in an aqueous phase using tricalcium phosphate or polyvinyl alcohol as a suspending agent,
Usually, suspension polymerization (main polymerization) until the degree of polymerization approaches 100%.
I do. If necessary, heating may be further continued after this main polymerization step.

Examples of the molecular weight modifier include mercaptans such as α-methylstyrene dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, 1-phenylbutene-2-fluorene, dipentene and chloroform, terpenes, halogen compounds and the like. You can

Examples of the polymerization initiator used as desired include peroxy compounds such as 1,1-bis (t-butylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane. Ketals, dicumyl peroxide, di-t-butyl peroxide, 2,5
-Dialkyl-2,5-di (t-butylperoxy) hexane and other dialkyl peroxides, benzoyl peroxide, m-toluoyl peroxide and other diallyl-
Peroxides, peroxydicarbonates such as dimyristyl peroxydicarbonate, peroxyesters such as t-butylperoxyisopropyl carbonate, ketone peroxides such as cyclohexanone peroxide, organic peroxidation such as hydroperoxides such as p-menthane hydroperoxide You can list things.

Note that the particle size, particle size distribution, and particle structure of the rubber-like polymer can be controlled by the stirring rotation speed and the amount of the molecular weight regulator used, and the gel amount and the swelling index are the type and amount of the catalyst, It can be controlled by the reaction temperature, reaction time and the like.

Next, the slurry thus obtained is treated by an ordinary means to take out a bead-like reaction product, which is dried and then pelletized according to a conventional method to form a rubber-modified styrene having a dispersed rubber form having an occlusion structure. A system polymer is obtained.

The molecular weight of the matrix portion of the rubber-modified styrenic resin composition thus obtained is advantageously in the range of 100,000 to 300,000, preferably 130,000 to 280,000. If the molecular weight is less than 100,000, the impact resistance is poor, and 300,000
If it exceeds, the fluidity during molding becomes insufficient.

In the present invention, a flame retardant is used as the component (b). As the flame retardant, various flame retardants can be mentioned, but a halogen flame retardant and a phosphorus flame retardant are particularly preferable.

Examples of halogen-based flame retardants include tetrabromobisphenol A, tetrabromophthalic anhydride, hexabromobenzene, tribromophenyl allyl ether, pentabromotoluene, pentabromophenol, tribromophenyl-2,3-dibromo-propyl ether, tris. (2,3-dibromopropyl) phosphate, tris (2-chloro-3-bromopropyl) phosphate, octabromodiphenyl ether, decabromodiphenyl ether, octabromobiphenyl, pentachloropentacyclodecane, hexabromocyclododecane, hexachlorobenzene, penta Chlorotoluene, hexabromobiphenyl, decabromobiphenyl, decabromobiphenyl oxide, tetrabromobutane, decabromodiphenyl ether, hexab Mo diphenyl ether, ethylene - bis - (tetrabromophthalimide), tetrachlorobisphenol A, tetrachlorobisphenol A
Or an oligomer of tetrabromobisphenol A, a halogenated polycarbonate oligomer, a halogenated epoxy compound, polychlorostyrene, brominated polystyrene such as polytribromostyrene, poly (dibromophenylene oxide), etc., and further brominated polystyrene such as polytribromostyrene. And so on.

On the other hand, examples of the phosphorus-based flame retardant include ammonium phosphate, tricresyl phosphate, triethyl phosphate, acidic phosphoric acid ester, triphenylphosphine oxide and the like.

Of these, decabromodiphenyl ether and tetrabromobisphenol A are particularly preferable as the flame retardant.

There are various flame retardant aids, for example, antimony trioxide, antimony pentaoxide, sodium antimonate, metal antimony, antimony trichloride, antimony pentachloride, antimony trisulfide, antimony pentasulfide, etc. Examples include auxiliary agents. Other than these, zinc borate, barium metaborate, zirconium oxide and the like can be mentioned.

Among these, antimony trioxide is particularly preferable as the component (c).

The component (b) (flame retardant) is contained in an amount of 3 to 40 parts by weight, preferably 5 to 35 parts by weight, per 100 parts by weight of the component (a). If the content ratio of the component (b) is less than 3 parts by weight, the flame retardancy of the obtained resin composition is insufficient.
On the other hand, even if it exceeds 40 parts by weight, the flame retardancy is not improved depending on the ratio, and conversely, other mechanical properties are impaired, which is not preferable.

In addition, it is necessary to appropriately select the type and the addition amount of the component (b) according to the purpose of use. For example, in the field where heat resistance is particularly important, such as used for home electric appliances, those having a high melting point (250 ° C. or higher) such as decabromodiphenyl ether and hexabromobenzene may be used. As for the amount added, it is V-2 in UL standard.
When sufficient flame retardancy is obtained, a ratio of about 3 to 10 parts by weight is preferable, and when flame retardancy equivalent to V-1 to V-0 is required, 11 to 40 parts by weight is preferable. It is preferably used in the range.

The component (c) is 1 to 1 with respect to 100 parts by weight of the component (a).
It is contained in an amount of 5 parts by weight, preferably 2 to 10 parts by weight. Here, if the content ratio of the component (c) is less than 1 part by weight, the effect as a flame retardant aid is not sufficient. On the other hand, if the amount exceeds 15 parts by weight, the effect as a flame retardant aid is not improved depending on the ratio, and conversely, other physical properties may be impaired, which is not preferable.

The flame-retardant resin composition of the present invention can be obtained by blending each of these components in a predetermined amount, and the production method may be according to a conventional method. For example, each component is premixed by a mixer such as a Henschel mixer, a tumbler blender, and a kneader, and then kneaded by an extruder, or melt-kneaded by a heating roll and a Banbury mixer. The mixing and kneading order of each component is not particularly limited,
The components (a), (b) and (c) may be mixed and kneaded at the same time, or any two components may be mixed and kneaded and then the other components may be mixed and kneaded.

The rubber-modified styrenic resin composition may optionally contain various additives that are usually used, such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and lubricants such as ethylene bisstearamide. , Organic polysiloxane, mineral oil, or 2,6-di-t-butyl-4-methylphenol, stearin-β- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate, triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate and other hindered phenolic compounds and tri (2,4-di-t-butylphenyl) ) Phosphite, phosphorus-based antioxidants such as 4,4'-butylidene bis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite, other ultraviolet absorbers, antistatic agents, release agents, Plasticizers, dyes, pigments, various fillers and the like can be added. In addition, other polymers such as polystyrene and polyphenylene ether may be added.

[Examples] Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Production Example 1 A styrene-butadiene block copolymer (manufactured by Bayer Co., Ltd.) was placed in an autoclave with an internal volume of 5 and a squid-type stirring blade.
BL6533, molecular weight 230,000, styrene content 40%) 527g, polybutadiene (BR15HB made by Ube Industries, molecular weight 550,00)
0) 132 g, styrene 3000 g, and n-dodecyl mercaptan 1 g as a chain transfer agent were added, and the mixture was stirred at 400 rpm.
Bulk polymerization reaction was carried out at 0 ° C. for 4 hours.

Then, in an autoclave with an internal volume 10 squid-type stirring blade, the reaction mixture 3000 g, water 3000 g, polyvinyl alcohol 10 g as a suspension stabilizer, benzoyl peroxide 6 g and dicumyl peroxide 3 g as a polymerization initiator, and at 300 rpm. While stirring, the temperature was raised from 80 ° C. to 140 ° C. at a heating rate of 30 ° C./hr, and the reaction was continued for another 4 hours at that temperature to obtain beads of the rubber-modified polystyrene composition.

The beads were pelletized by a single screw extruder at 220 ° C.
When the obtained pellets were analyzed by an electron microscope, they had an occlusion structure in which the area average particle diameter was 0.50 μm and the ratio of the area average particle diameter to the number average particle diameter was 2.2. In addition, the physical properties of the molded product are 96% gloss and Izod impact strength.
It was 14.8 kg cm / cm. This copolymer had a rubber-like polymer content of 18% by weight and a molecular weight of 210,000.

Production Example 2 In Production Example 1, the rotation speed of the stirring blade in the bulk polymerization was
The same procedure as in Production Example 1 was performed except that the speed was set to 500 rpm.

The obtained rubber-modified polystyrene composition has an area average particle size.
It has 90% of occlusion structure of 0.41μm and the ratio of area average particle diameter to number average particle diameter is 2.1, and gloss is 9
The Izod impact strength was 9% and 10.6 kg cm / cm. This copolymer has a rubber-like polymer content of 18% by weight,
The molecular weight was 215,000.

Example 1 100 parts by weight of the rubber-modified polystyrene composition obtained in Production Example 1, 23 parts by weight of decabromodiphenyl ether (SAYTEX102 manufactured by Ethyl Corporation) as a flame retardant, and antimony oxide (Nippon Seiko Co., Ltd.) as a flame retardant aid. Made
8 parts by weight of ATOX-S) was pre-blended with a super rotor (manufactured by Kawada Manufacturing Co., Ltd.). Then, the blend was melt-kneaded at a cylinder temperature of 210 ° C. by a single-screw extruder and injection-molded to prepare a test piece. The physical properties of this test piece are shown in Table 1.

Example 2 In Example 1, decabromodiphenyl ether was added to 8
It was carried out in the same manner as in Example 1 except that 5 parts by weight of antimony oxide and 4 parts by weight of tetrabromobisphenol A (SAYTEX RB-100PC manufactured by Ethyl Corporation) were added as a flame retardant. The physical properties of the obtained test pieces are shown in Table 1.

Example 3 In Example 1, the rubber-modified polystyrene composition obtained in Production Example 2 was used in place of the rubber-modified polystyrene composition obtained in Production Example 1, 15 parts by weight of decabromodiphenyl ether was added, and antimony oxide was used. Was carried out in the same manner as in Example 1 except that 10 parts by weight was added. The physical properties of the obtained test pieces are shown in Table 1.

Comparative Example 1 In Example 1, instead of the rubber-modified polystyrene composition obtained in Production Example 1, a rubber-modified polystyrene composition having a salami structure (Idemitsu Styrol manufactured by Idemitsu Petrochemical Co., Ltd.) was used.
Example 1 was repeated except that HT50) was used.

Comparative Example 2 In Example 1, 2 parts of decabromodiphenyl ether was added.
The same procedure as in Example 1 was repeated except that the amount of tetrabromobisphenol A was 2 parts by weight.

Comparative Example 3 In Example 3, decabromodiphenyl ether was added to 23
Parts by weight, 16 parts by weight of antimony oxide, and tetrabromobisphenol A as a flame retardant, and the same procedure as in Example 3.

The physical properties of Comparative Examples 1 to 3 are shown in Table 1.

The physical properties of the test pieces were measured by the following methods.

Gloss: Complies with JIS K-7105.

Izod impact strength: Complies with JIS K-7110 (23 ° C notched).

Flammability: Compliant with US UL94 standard (however, the thickness of the test piece is
1/16 inch).

[Effects of the Invention] The flame-retardant styrene resin composition of the present invention has a high balance of physical properties such as high impact strength and excellent gloss and rigidity because the dispersed rubber form has an occluded structure, and It has excellent flame retardancy.

Claims (1)

[Claims] 1. A rubber-modified styrene resin composition comprising 100 parts by weight of (a) a styrene polymer and a rubbery polymer,
(B) a composition containing 3 to 40 parts by weight of a flame retardant and (c) 1 to 15 parts by weight of a flame retardant auxiliary, and the rubber-like polymer in the component (a) is a styrene-butadiene type The block copolymer rubber and the polybutadiene rubber are compounded in a ratio of former / latter = 10/0 to 6/4 (weight ratio),
The area average particle diameter (diameter) is 0.4 to 0.6 μm,
In the dispersed rubber form, one rubber particle contains 5 or less inclusion occlusions in which the core is a styrenic polymer and the shell is a rubbery polymer, and at least 50% or more of the inclusion occlusions are included. A flame-retardant styrenic resin composition, which has 70% or more of one occlusion structure.