JPH0686561B2 - Monovinyl aromatic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a monovinyl aromatic resin composition having excellent impact resistance and flame retardancy. INDUSTRIAL APPLICABILITY The resin composition of the present invention can be effectively used as various industrial materials such as electric product materials, particularly as a material in the field requiring flame retardancy.

[Problems to be Solved by Prior Art and Invention]

Conventionally, a method of increasing the amount of rubber such as polybutadiene to be used is known as a method of improving the impact resistance of high impact polystyrene (HI-PS) and the like. Since the viscosity of the polymer increases, a large amount of energy is required for the polymerization, and it becomes difficult to control the reaction, there are many problems in industrial practice.

Further, a method of using a rubber that gives higher impact resistance has been studied, but a satisfactory method has not been obtained yet.

On the other hand, a flame retardant is added to make the styrene resin flame-retardant. However, the addition of the flame retardant causes a problem that the impact resistance is significantly lowered. Various methods for improving this have been studied, but the current situation is that no satisfactory method has been obtained.

The present inventor has variously studied a method for improving both impact resistance and flame retardancy of a monovinylaromatic resin composition by a simple method using high cis polybutadiene, and as a result, a monovinylaromatic monomer having a specific ratio of A composition having a swelling index of 16 to 25 of a rubber-like soft component obtained by polymerizing high cis polybutadiene in the presence of an antioxidant, which is obtained by graft polymerization of the high cis polybutadiene with a monovinyl aromatic monomer. It was found that a monovinylaromatic resin composition obtained by adding a flame retardant and a flame retardant auxiliary to a product in a specific ratio meets this purpose. The present invention has been completed based on this finding.

[Means for solving problems]

That is, the present invention relates to 85 to 98% by weight of a monovinyl aromatic monomer, 15 to 2% by weight of high cis polybutadiene, and 0.1 to 0.5% by weight of a hindered phenolic antioxidant to the high cis polybutadiene as an antioxidant. % And 0.02 to 0.2% by weight of a phosphorus-based antioxidant, respectively, and polymerized to obtain a resin composition in which a rubber-like soft component produced by graft polymerization of the high-cis polybutadiene with an aromatic monomer is dispersed. 2 to 40 parts by weight of a flame retardant and 0.5 parts of a flame retardant aid with respect to 100 parts by weight of a composition having a swelling index of the soft component of 16 to 25 (hereinafter simply referred to as "composition"). The present invention provides a monovinyl aromatic resin composition (hereinafter, referred to as "resin composition"), which is obtained by adding -15 parts by weight.

Examples of the monovinyl aromatic monomer used in the present invention include not only styrene alone but also a mixture of styrene and another vinyl-based monomer copolymerizable with styrene. Specific examples of other vinyl-based monomers that can be copolymerized with styrene include methylmethacrylate, methylacrylate, ethylmethacrylate, acrylonitrile, methacrylonitrile, halogen-containing vinyl monomers, α-methylstyrene, o-methylstyrene. and m-methylstyrene, p-methylstyrene and the like. These vinyl monomers copolymerizable with styrene are usually used in a proportion of 30% by weight or less, preferably 10% by weight or less, based on the total monomers.

Next, in the present invention, high cis polybutadiene is used.
Here, high cis polybutadiene refers to polybutadiene containing a large amount of 1,4-cis bonds, and is usually polybutadiene containing 78 mol% or more, preferably 80 to 97 mol% of 1,4-cis bonds. When the 1,4-cis bond content is less than 78 mol%, the impact resistance of the obtained resin composition cannot be improved. The content of 1,2-vinyl bonds in this high-cis polybutadiene is usually 20 mol% or less, preferably 1 to 10 mol%. 1,2-vinyl bond content of 20
If it exceeds mol%, the impact resistance of the obtained resin composition is deteriorated, which is not preferable. Further, the content of 1,4-trans bonds in this high-cis polybutadiene is usually 2 mol%.
It is the following.

This high-cis polybutadiene can be produced, for example, by polymerizing 1,3-butadiene using a catalyst containing an organoaluminum compound and a cobalt or nickel compound. The microstructure of this high-cis polybutadiene can be determined by measuring its infrared absorption spectrum and using the Morello method or the like. Further, this high-cis polybutadiene has a solution viscosity in a 5% styrene solution at 25 ° C. of usually 20 to 200 cSt, preferably 30 to 150 cSt. Here, if the solution viscosity is less than 20 cSt, the impact resistance of the obtained resin composition is lowered, which is not preferable. On the other hand, if the solution viscosity exceeds 200 cSt, the appearance of the obtained resin composition deteriorates, which is not preferable.

Further, in the present invention, a hindered phenol-based antioxidant and a phosphorus-based antioxidant are used as the antioxidant. Specific examples of the hindered phenol antioxidant include n-octadecyl-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate (trade name: Irganox 1076, a trademark owned by Ciba Geigy); 3,5
-Di-t-butyl-4-hydroxytoluene (BHT); 1,
3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (trade name: ethyl 330, a trademark owned by Ethyl Incorporated); 2-t-butyl- 6- (3
-T-butyl-2-hydroxy-5-methylbenzyl)
-4-Methylphenyl acrylate (trade name: Sumilizer GM, a trademark owned by Sumitomo Chemical Co., Ltd.); 1,3,5-tolyl (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) -1 , 3,5-Triazine; 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane; tetrakis (methylene 3- (3,5-di-t-butyl-4-) (Hydroxyphenyl) propionate) methane (trade name: Irganox 1010, a trademark owned by Ciba Geigy); Others: Kirk-Othmer Encyclopedia of Chemical Technolog
y), 3rd edition, vol. 3, p.129-133.

Specific examples of phosphorus-based antioxidants include triphenyl phosphite, tridecyl phosphite, tris (nonylphenyl) phosphite, tridecyl trithiophosphite, butyl acid phosphate, β-chloroethyl acid phosphate, and the like. To be

In addition, if necessary, an amine-based antioxidant such as phenyl / α-naphthylamine or phenyl / β-naphthylamine may be used in combination.

The composition of the present invention is obtained by adding high cis polybutadiene, a hindered phenol-based antioxidant and a phosphorus-based antioxidant to the above-mentioned monovinyl aromatic monomer and polymerizing them, in which the soft component is dispersed. It is a thing.

Here, the blending ratio of the monovinyl aromatic monomer and the high-cis polybutadiene is 85 to 98% by weight of the former, preferably 87 to 95% by weight, and 15 to 2% by weight of the latter, preferably 12 to 5% by weight. . 15% by weight of high cis polybutadiene
When it exceeds, the viscosity of the polymerization system becomes high and the reaction control becomes difficult. On the other hand, if it is less than 2% by weight, impact resistance of the obtained resin composition is deteriorated, which is not preferable.

Further, the blending ratio of the antioxidant is such that the hindered phenolic antioxidant is 0.1 to the high cis polybutadiene.
0.5% by weight and 0.02 to 0.2% by weight of phosphorus antioxidant. By blending these antioxidants in the above range, a resin composition having excellent impact resistance can be obtained.

In the present invention, the above-mentioned antioxidant needs to be added before the polymerization of the monovinyl aromatic monomer and the high-cis polybutadiene, and even if it is added after the polymerization, the impact resistance cannot be improved. Therefore, the above antioxidant is usually added to the monovinyl aromatic monomer together with the high cis polybutadiene, but it may be added in a predetermined amount at the time of producing the high cis polybutadiene.

The composition of the present invention is a composition in which the soft component thus obtained is dispersed, but in the present invention, it is necessary that the swelling index of the soft component is 16 to 25.

Here, the swelling index of the soft component refers to the degree of swelling of the insoluble portion of the composition with toluene. Specifically, an example in which 2.0 g of the composition is dissolved in 100 ml of toluene, an insoluble matter is separated by centrifugation, and the insoluble matter, that is, a wet soft component is weighed to obtain Ag. Next, the wet soft component is reprecipitated with methanol and then dried in vacuum for one day, and the dry soft component is weighed to obtain Bg. The swelling index of the soft component is represented by A / B. Here, the swelling index can be adjusted by appropriately changing the blending ratio of the monovinyl aromatic monomer and the high-cis polybutadiene used, the amount of the polymerization catalyst, the polymerization temperature, and the blending amount of the antioxidant.

In the present invention, the swelling index of the soft component needs to be within the range of 16 to 25, and particularly preferably within the range of 17 to 23. If the swelling index of the soft component is out of this range, the impact resistance of the resin composition is reduced, which is not preferable.

The composition of the present invention having such characteristics can be produced by any known polymerization method as long as the above characteristics can be satisfied. Specific examples of such known polymerization methods include bulk polymerization, bulk-suspension polymerization, and emulsion polymerization. Among these polymerization methods, it is preferable to use a bulk polymerization method or a bulk-suspension polymerization method in which styrene is polymerized in the presence of a rubber-like elastic material.

Next, an example of the method for producing the composition of the present invention will be described by the bulk-suspension polymerization method.

First, a predetermined amount of high cis polybutadiene containing an antioxidant or high cis polybutadiene and an antioxidant is added to a monovinyl aromatic monomer. At this time, it is heated and dissolved if necessary, but this dissolution is preferably carried out as uniformly as possible. Next, in the presence of a molecular weight regulator such as an alkyl mercaptan and a polymerization catalyst such as a diacyl peroxide or a dialkyl peroxide, which is used if necessary, 90 to 150
Preliminary polymerization is carried out by bulk polymerization with stirring at a temperature of ° C for 1 to 5 hours. This prepolymerization is carried out until the degree of polymerization of the monovinyl aromatic monomer reaches about 10 to 40%, and in this prepolymerization, the soft component is dispersed into particles by stirring.

Further, after the completion of the prepolymerization, the obtained polymer is suspended in an aqueous phase containing tricalcium phosphate, polyvinyl alcohol and the like as a suspending agent, and suspension polymerization (main polymerization) is carried out until the polymerization rate becomes around 100%. The conditions for this suspension polymerization are that the polymerization rate is
There is no particular limitation as long as it is 100% in recent years,
It is usually at a temperature of 110 to 140 ° C. for 7 to 12 hours. If necessary, heating can be continued after the main polymerization.

The composition thus obtained can be produced by dehydrating the slurry thus obtained, separating and drying the beads, and then pelletizing the beads by a conventional method. When carrying out the polymerization, a polymerization initiator, a suspension stabilizer, a molecular weight modifier, a polymerization catalyst and the like which are usually used as described above can be used.

The composition obtained as described above is a dispersion of the soft component. The swelling index of the soft component can be adjusted by appropriately changing the mixing ratio of the monovinyl aromatic monomer and the high-cis polybutadiene used, the amount of the polymerization catalyst, the polymerization temperature, and the amount of the antioxidant, as described above. You can do it.

The resin composition of the present invention is obtained by adding 2 to 40 parts by weight of a flame retardant and 0.5 to 15 parts by weight of a flame retardant aid to 100 parts by weight of the above composition.

Here, examples of the flame retardant include organic halogen type and phosphorus type. Specific examples of organic halogen-based flame retardants include hexabromobenzene, hexachlorobenzene, pentabromotoluene, pentachlorotoluene, pentabromophenol, pentachlorophenol, hexabromobiphenyl, decabromodephenyl, tetrabromobutane, hexabromo. Cyclododecane, perchloropentacyclodecane, decabromodiphenyl ether,
Octabromodiphenyl ether, hexabromodiphenyl ether, tetrabromobisphenol S, tetrabromobisphenol A, tetrabromobisphenol S oligomer, tetrabromobisphenol A oligomer, ethylene-bis- (tetrabromophthalimide),
Tetrachlorobisphenol A, low molecular weight organohalogen compound of tetrachlorobisphenol A, halogenated polycarbonate oligomer, halogenated epoxy compound,
Brominated polystyrene such as polychlorostyrene and polytribromostyrene, poly (dibromophenylene oxide)
And the like. Specific examples of phosphorus-based flame retardants include ammonium phosphate, tricresyl phosphate, triethyl phosphate, acidic phosphates, triphenylphosphene oxide, and the like. Among these flame retardants, organic bromine-based ones are particularly preferable.

This flame retardant is 2 to 40 parts by weight with respect to 100 parts by weight of the composition.
Parts by weight, preferably 5 to 30 parts by weight, are added.
If the amount of the flame retardant added is less than the above ratio, the flame retardancy cannot be sufficiently improved. On the other hand, if the amount of the flame retardant added is larger than the above-mentioned ratio, the impact resistance of the obtained resin composition is significantly lowered, which is not preferable.

Next, as flame retardant aids, antimony-based compounds such as antimony trioxide, sodium antimonate, metallic antimony, antimony trichloride, antimony pentachloride, antimony trisulfide, antimony pentasulfide, antimony pentaoxide, and zinc borate are used. , Barium metaborate, zirconium oxide, etc. can be used.

This flame retardant aid is 0.5 to 100 parts by weight of the composition.
15 parts by weight, preferably 1 to 10 parts by weight are added. If the amount of the flame retardant aid added is less than the above ratio, flame retardancy cannot be sufficiently improved. On the other hand, if the amount of the flame retardant aid added is more than the above-mentioned ratio, the impact resistance of the obtained resin composition is significantly lowered, which is not preferable.

The resin composition of the present invention can be produced by a conventional method. That is, the composition and the flame retardant and the flame retardant aid obtained as described above are premixed with a mixer such as a Henschel mixer, a tumbler blender, a kneader, and then kneaded with an extruder, or a heating roll, It can be produced by melt-kneading with a Banbury mixer.

At this time, if necessary, in addition to a colorant, a plasticizer, a stabilizer, an ultraviolet absorber, a release agent, a foaming agent, an inorganic filler, a thermoplastic elastomer or the like may be added.

〔The invention's effect〕

The monovinyl aromatic resin composition of the present invention has excellent flame retardancy.

Moreover, the monovinyl aromatic resin composition of the present invention is a composition containing a flame retardant, but does not have a significant decrease in impact resistance as seen in conventional impact-resistant polystyrene, and also has impact resistance. It can be said to be excellent.

Therefore, the present invention can be effectively used as a material particularly in the field where flame retardancy is required.

〔Example〕

 Next, the present invention will be described with reference to examples.

Examples 1-9 and Comparative Examples 1-2 Predetermined amount of high cis polybutadiene A (1,4-cis bond 95 mol%; 1,4-trans bond 3 mol%; 1,3) in styrene in a polymerization tank equipped with a stirrer. 2-Vinyl bond 2 mol%; solution viscosity 35 cSt; antioxidant Irganox 1076 (Ciba Geigy)
2% by weight, BHT 0.1% by weight, tris (nonylphenyl) phosphite [TNP] 0.1% by weight) were dissolved, and 1,1-
Di-t-butylperoxy-3,3,5-trimethylcyclohexane (catalyst) and lauroyl mercaptan (molecular weight regulator) were added, and the mixture was polymerized with stirring at 110 ° C for 1 to 3 hours and 130 ° C for 1 to 3 hours. Was done.

Next, the obtained polymer is added to and dispersed in an aqueous phase of a polymerization tank equipped with a stirrer, and then benzoyl peroxide and di-t-butyl peroxide (polymerization initiator) and a suspension stabilizer are added thereto. Polymerization was carried out at 100 to 150 ° C for 3 to 12 hours.

The obtained granular resin composition is filtered, dried and pelletized,
A predetermined flame retardant and a flame retardant auxiliary agent (Sb ₂ O ₃ ) were added and injection molding was performed to manufacture a test piece. The physical properties of this test piece are shown in Table 1.

Comparative Example 3 In Example 1, instead of high cis polybutadiene A, low cis polybutadiene (1,4-cis bond 39 mol%; 1,4-
Example 1 was repeated except that 51 mol% of trans bond; 10 mol% of 1,2-vinyl bond) was used, and the same amount of the same antioxidant was added and dissolved in styrene. The results are shown in Table 1.

Comparative Example 4 In Example 4, low cis polybutadiene (the same as Comparative Example 3) was used in place of the high cis polybutadiene A,
Further, the same procedure as in Example 1 was performed except that the same amount of the same antioxidant was added and dissolved in styrene. The results are shown in Table 1.

Examples 10 to 11 and Reference Example In Example 1, high-cis polybutadiene B was replaced by high-cis polybutadiene B (1,4-cis bond 93 mol%; 1,4
-Trans bond 1 mol%; 1,2-vinyl bond 6 mol%; dissolution viscosity 65 cSt), and a predetermined amount of the antioxidant shown in Table 1 was added and dissolved in styrene. Example 1 except that a flame retardant and a flame retardant aid were used.
It carried out similarly to. The results are shown in Table 1.

Comparative Example 5 The procedure of Example 10 was repeated, except that the antioxidant was not added when styrene was dissolved, and the antioxidant was added and kneaded after the completion of the polymerization. The results are shown in Table 1.

Comparative Example 6 Comparative Example 5 was carried out in the same manner as Comparative Example 5 except that the flame retardant and the flame retardant auxiliary were not added. The results are shown in Table 1.

Example 12 In Example 4, except that high cis polybutadiene B (the same as Examples 10 to 11) and low cis polybutadiene (the same as Comparative Example 3) were used in combination in place of high cis polybutadiene A. The same procedure as in 4 was performed. The results are shown in Table 1.

* 1 High cis polybutadiene A: High cis polybutadiene A B: High cis polybutadiene B Low cis: Low cis polybutadiene * 2 Antioxidant The amount of the antioxidant is the weight% based on polybutadiene. The abbreviations indicate the following.

1076: Irganox 1076 (Ciba Geigy) GM: Sumilizer GM (Sumitomo Chemical Co., Ltd.) * 3 Flame retardant TBA: Tetrabromobisphenol A TBA-O: Tetrabromobisphenol A oligomer TBS: Tetrabromobisphenol S FF680: 1,2-Bis (2,4,6-tribromo-phenyloxy) ethane [Product name of Great Lakes] DBDPE: Decabromodiphenyl ether TBS-O: Tribromostyrene oligomer * 4 Drop weight impact strength With a 1/2 inch φ lead, 1.0
Test piece (width 70mm, length 270mm, thickness 3m)
The energy at which 50% of the test piece breaks when hit at a point 125 mm from the gate of m) is shown.

* 5 Flame retardant Compliant with US UL94 standard

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area C08K 5/52

Claims (1)

[Claims] 1. A monovinyl aromatic monomer of 85 to 98% by weight, high cis polybutadiene of 15 to 2% by weight, and a hindered phenolic antioxidant of 0.1 to 0.5% by weight based on the high cis polybutadiene as an antioxidant. % And a phosphorus-based antioxidant with 0.02 to 0.2% by weight, respectively, and a resin composition in which a rubber-like soft component produced by graft-polymerizing high-cis polybutadiene with a monovinyl aromatic monomer is obtained by polymerization. Monovinyl fragrance obtained by adding 2 to 40 parts by weight of a flame retardant and 0.5 to 15 parts by weight of a flame retardant aid to 100 parts by weight of a composition having a swelling index of the soft component of 16 to 25. Group resin composition.