JPH10110076A - Flame-retardant styrene resin composition of melt dripping type under fire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flame-retardant styrene resin compsn. which is excellent in melt dripping properties under fire without detriment to physical properties such as gloss and at a low level of a flame retardant compounded by compounding a rubber-modified polystyrene resin with a specific polysiloxane. SOLUTION: This compsn. is prepd. by compounding a rubber-modified polystyrene resin, 0.001-0.005wt.% organopolysiloxane contg. 90% or higher structural units represented by the formula, and a halogen or phosphorus flame retardant, satisfies the specifications of the vertical burning test of UL94 V2 (USA), and is excellent in the balance among impact resistance, gloss, and stiffness. The rubber-modified polystyrene resin pref. comprises an arom. vinyl polymer matrix and rubbery polymer particles dispersed therein and pref. has a rubber content of 3-18wt.%. The organopolysiloxane is pref. polydimethylsiloxane and may be added at the polymn. step in producing the rubber-modified polystyrene resin or may be melt mixed with the resin on an extruder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition-melt-dropping type flame-retardant styrene resin composition. More specifically, the present invention relates to a styrene-based resin composition having excellent fire extinguishing property during burning while maintaining a high balance of physical properties.

[0002]

2. Description of the Related Art Rubber-modified polystyrene resins represented by impact-resistant polystyrene are excellent in impact resistance in addition to moldability and dimensional stability. It is used. However, rubber-modified polystyrene resins are flammable, and are used by blending a flame retardant in applications requiring higher flame retardancy. In recent years, even in fields requiring high flame retardancy, even higher impact resistance and appearance characteristics have been required.

As a method for making a rubber-modified polystyrene resin flame-retardant, it is known to add a halogen-based, phosphorus-based, or inorganic-based flame retardant, whereby the flame retardation is achieved to some extent. However, in recent years, the demand for fire safety has been particularly noticed, and the fields of application that are required to satisfy the standards of the United States UL (Underwriters Laboratory) vertical combustion test for home electric appliances, office equipment, etc. are expanding. Higher flame retardancy is required. There is a method to increase the amount of flame retardant to make it more highly flame-retardant, but using a large amount of an inherently expensive flame retardant is not only economical, but also to reduce the mechanical properties. Not preferred. For this reason, there has been a demand for the development of a technique for making a resin flame-retardant using as little flame retardant as possible.

[0004] As a conventional known technique relating to UL94V2, a post-ignition, melt-dropping, self-extinguishing styrenic resin composition comprising a rubber-modified polystyrene resin having a specific average rubber particle diameter and a halogen-based flame retardant (Japanese Patent Publication No. 6-43542). ) Is disclosed. This technique focuses on the particle diameter of the rubber component contained therein, and discloses that ignition and melting are facilitated by reducing the particle diameter. However, reducing the particle size causes a problem that the impact resistance is reduced. As a technique for improving the impact resistance of a rubber-modified polystyrene resin having a small particle diameter, a method of containing an organic polysiloxane (JP-A-57-170)
950, JP-A-57-187346), but the composition of JP-B-6-43542 does not pass the UL94V2 standard when an organic polysiloxane is used in combination with a halogen-based flame retardant. No technology has been provided that simultaneously satisfies a higher balance of physical properties and flammability.

[0005]

SUMMARY OF THE INVENTION The present invention provides a styrenic resin composition which has less flame retardant and which is excellent in ignition melting dripping property without impairing impact resistance and glossiness.

[0006]

Means for Solving the Problems The present inventors have intensively studied an improvement technique of a flame-retardant styrene resin having excellent impact resistance and appearance properties, and as a result, found that a very small amount was contained in a rubber-modified polystyrene resin. It has been found that the impact strength is greatly improved without impairing the fire-extinguishing property by dropping by containing the organic polysiloxane of the formula (1). That is, by combining (A) a rubber-modified styrene-based resin containing an organic polysiloxane in a specific trace amount range and (C) a halogen-based or phosphorus-based flame retardant, excellent ignition melting dripping property and balance of physical properties are obtained. Have been found to be greatly improved, and the present invention has been achieved.

The present invention relates to (A) a rubber-modified polystyrene resin, and (B) 90% of a structural unit represented by the following formula (1).
The organopolysiloxane having the above amount of 0.001 to 0.005
A flame-retarded flammable styrene-based resin composition, characterized in that the composition comprises, by weight, and (C) a halogen-based and / or phosphorus-based flame retardant.

[0008]

Embedded image

(A) As the rubber-modified styrene resin,
A polymer in which a rubbery polymer is dispersed in the form of particles in a matrix composed of a vinyl aromatic polymer.A bulk polymerization, solution polymerization or suspension polymerization of an aromatic vinyl monomer in the presence of a rubbery polymer. It is obtained by turbid polymerization. As the aromatic vinyl monomer, styrene, o-methylstyrene, m-
Alkylstyrene such as methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, α-methylstyrene,
α-alkyl-substituted styrenes such as α-methyl-p-methylstyrene. Representative examples include styrene alone or a monomer in which a part of the styrene is replaced with the above-mentioned aromatic vinyl monomer other than styrene.

The rubber-modified styrenic resin includes monomers copolymerizable with an aromatic vinyl monomer, for example, acrylate monomers such as butyl acrylate, and methacrylate esters such as methyl methacrylate. One or more monomers may be introduced. . For a rubbery polymer, the glass transition temperature (Tg) needs to be -30 ° C or lower, and if it exceeds -30 ° C, the impact resistance decreases. Examples of such rubbery polymers include polybutadiene, styrene-butadiene copolymer, diene rubber such as acrylonitrile-butadiene copolymer, and saturated rubber obtained by hydrogenating the diene rubber, isoprene rubber, chloroprene rubber, Acrylic rubber such as polybutyl acrylate and ethylene-propylene-diene terpolymer (EPDM)
And the like, and a diene rubber is particularly preferable.

The rubbery polymer in the rubber-modified styrenic resin (A) of the present invention is required to be 3 to 18% by weight.
%, The impact strength decreases, and if it exceeds 18%, the rigidity and
Characteristics such as fluidity and flame retardancy are undesirably reduced. The size of the rubber particles to be dispersed is preferably in the range of 0.8 to 1.8 μm, and particularly from the balance of impact strength and gloss.
8-1.3 μm is more preferred.

The reduced viscosity ηsp / C of the matrix in the rubber-modified styrenic resin (A) of the present invention is 0.40
dl / g to 1.00 dl / g is preferable, and especially 0.50
dl / g to 0.80 dl / g is preferred. 0.40dl
If it is less than / g, the melt-dropping property is improved, but the impact strength becomes insufficient. If it exceeds 1.00 dl / g, sufficient melt-dropping property is not obtained, and it is difficult to secure practical fluidity. Means for satisfying the reduced viscosity ηsp / C of the rubber-modified styrene resin include adjustment of the polymerization initiator amount, the polymerization temperature, and the chain transfer agent amount.

(B) used in the present invention is an organic polysiloxane containing 90% or more of the structural unit represented by the formula (1), and its addition amount is 0.001 to 0.005% by weight.
It is. If the added amount is less than 0.001% by weight, the effect of improving the impact strength is small, and if it is 0.005% by weight or more, the flammability becomes poor and more flame retardant is required. Also,
Sufficient impact strength cannot be obtained with an organic polysiloxane in which the structural unit represented by the formula (1) is less than 90% by weight.

The solution viscosity of the organic polysiloxane at 25 ° C. is preferably 50 to 400 centistokes, and more preferably 100 to 200 centistokes. If the viscosity is out of the above range, no favorable results can be obtained. Preferably, the organic polysiloxane is polydimethylsiloxane. As a method for containing the organic polysiloxane of the present invention, an organic polysiloxane may be added to a polymerization composition of a styrene monomer or the like and polymerized, or a rubber-modified polystyrene resin and an organic polysiloxane may be extruded using an extruder or the like. Melt mixing may be performed. Further, a master pellet having a high concentration of organic polysiloxane may be produced from organic polysiloxane and polystyrene, and the master pellet and a rubber-modified polystyrene resin may be mixed to obtain a molded product.

In the present invention, (C) the halogen-based and / or phosphorus-based flame retardant component, and the halogen-based flame retardant includes halogenated bisphenols, aromatic halogen compounds, halogenated polycarbonates, halogenated aromatic vinyl-based flame retardants. Polymers, halogenated cyanurate resins, halogenated polyphenylene ethers and the like, preferably decabromodiphenyl oxide, tetrabromobisphenol A, oligomers of tetrabromobisphenol A, brominated bisphenol-based phenoxy resins, brominated polyphenylene oxide, polydibromo, deca Bromodiphenyl oxide bisphenol condensates, halogen-containing phosphoric acid esters, and the like can be given. These halogen-based flame retardants can be used in combination with antimony oxide.

The phosphorus-based flame retardant (C) in the present invention includes organic phosphorus compounds, red phosphorus, inorganic phosphates and the like. Examples of the organic phosphorus compound include phosphine, phosphine oxide, biphosphine, phosphonium salt, phosphinate, phosphate, phosphite and the like. More specifically, triphenyl phosphate, methyl neoventil phosphite, pentaerythritol diethyl diphosphite, methyl neopentyl phosphonate, phenyl neopentyl phosphate, pentaerythritol diphenyl diphosphonate, dicyclopentyl hypophosphite Fate, dineopentyl hypophosphite, phenylpyrocatechol phosphite, ethyl pyrocatechol phosphate, dipyrocatechol hypopositive phosphate.

As red phosphorus, besides general red phosphorus,
The surface of which is previously treated with a coating of a metal hydroxide selected from aluminum hydroxide, magnesium hydroxide, zinc hydroxide and titanium hydroxide. Examples of the inorganic phosphate include ammonium polyphosphate. In the present invention, the addition amount of the halogen-based and / or phosphorus-based flame retardant (C) is preferably 2 to 12 parts by weight, more preferably 4 to 8 parts by weight, based on 100 parts by weight of the rubber-modified styrene resin (A). . Although the flame retardancy improves as the amount of the flame retardant added increases, it is not economical, and the addition of the flame retardant unnecessarily leads to a decrease in physical properties.

The impact strength can be further increased by adding a metal salt of a higher fatty acid, an amide of a higher fatty acid, a styrene-butadiene copolymer elastomer or the like to the resin composition of the present invention. Further, the resin composition of the present invention, dyes and pigments, lubricants, fillers, release agents, plasticizers,
An ultraviolet absorber, an antioxidant, and the like may be added as needed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Measurement methods and raw materials in Examples and Comparative Examples will be described. (1) Rubber weight average particle diameter The rubber weight average particle diameter was determined by measuring the rubber-like polymer particles 1 in a transmission electron micrograph taken by an ultra-thin section method of the resin composition.
The particle size of 000 particles was measured and calculated by the following equation.

The weight average particle diameter ^{_{= Σn i · D i 4 /}} Σn i · D i 3 ( here n _i is the number of rubbery polymer particles having a particle diameter D _i) (2) reduced viscosity .eta.sp / C 1 g of rubber-modified styrenic resin has methyl ethyl ketone 18
and a mixed solvent of methanol and 2 ml of methanol.
Shake for 5 hours and centrifuge for 30 minutes at 5 ° C and 18000 rpm. After taking out the supernatant liquid after centrifugation and precipitating the resin component with methanol, using a vacuum dryer,
It was dried at 0 ° C. under normal pressure for 15 minutes, then under reduced pressure of 3-5 mmHg for 15 minutes, and cooled in a desiccator. 0.1 g of the resin thus obtained was dissolved in toluene to obtain a solution having a concentration of 0.5 g / dl. 10m of this solution
was placed in a Cannon-Fenske type viscosity tube, and the number of seconds t1 during which the solution flowed was measured at a constant temperature of 30 ° C. On the other hand, the number of seconds t0 during which pure toluene flows was measured using the same viscosity tube, and calculated by the following equation.

Ηsp / C = [(t ₁ / t ₀ ) −1] / C
(C = polymer concentration g / dl) (4) Izod impact strength According to ASTM-D256. (5) Gloss The average of the gloss values (the incident angle of 60 °) of the gate portion and the end portion of the dumbbell test piece of ASTM-D638 was determined. (6) Flame retardancy VB (Vertical Burn) based on UL-94
ing) method. (1/8 inch test piece) <Organic polysiloxane> (S-1): polymethylphenylsiloxane (methyl group / phenyl group = 19/1) (trade name KF-50-100CS, manufactured by Shin-Etsu Silicone Co., Ltd.) -2): Polydimethylsiloxane (manufactured by Toshiba Silicone Co., trade name: TSF451-100CS) (S-3): Polymethylphenylsiloxane (methyl group / phenyl group = 19/1) (manufactured by Shin-Etsu Silicone Co., trade name KF-) (S-4): Polymethylphenylsiloxane (methyl group / phenyl group = 3/1) (KF-54-400CS, manufactured by Shin-Etsu Silicone Co., Ltd.) <Production of rubber-modified styrene resin> (H -1): polybutadiene [(cis 1,4 bond / trans 1,4 bond / vinyl 1,2 bond weight ratio = 95/2)
/ 3) (Nippon 122, manufactured by Zeon Corporation)
0SL)] 6 parts by weight were dissolved in 84 parts by weight of styrene and 10 parts by weight of ethylbenzene, and 1,1-
0.03 parts by weight of bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, α-chain transfer agent
0.15 parts by weight of methylstyrene dimer was added to make a homogeneous mixture, and then continuously fed to a multistage reactor equipped with a stirrer equipped with a deaerator to polymerize, thereby obtaining a rubber content. 7
By weight, a rubber-modified styrene resin was obtained. The weight average particle diameter of the rubber of the obtained rubber-modified styrene resin is 1.3.
μ and reduced viscosity ηsp / C were 0.60. (H-2): polybutadiene [(cis 1,4 bond / trans 1,4 bond / vinyl 1,2 bond weight ratio = 32/4
8/20) (Nippon Elastomer Co., Ltd., Asaprene 7)
30A)] 6 parts by weight were dissolved in 84 parts by weight of styrene and 10 parts by weight of ethylbenzene, and 1,1-
0.03 parts by weight of bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, α-chain transfer agent
0.15 parts by weight of methylstyrene dimer was added to make a homogeneous mixture, and then continuously fed to a multistage reactor equipped with a stirrer equipped with a deaerator to polymerize, thereby obtaining a rubber content. 7
By weight, a rubber-modified styrene resin was obtained. The weight average particle diameter of the rubber of the obtained rubber-modified styrene resin is 1.3.
μ and reduced viscosity ηsp / C were 0.60. (H-3): The polymerization was carried out in the same manner as in (H-1), except that the stirring number of the multistage reactor was changed. The rubber of the obtained rubber-modified styrene resin had a weight average particle diameter of 0.95 μm and a reduced viscosity ηsp / C of 0.60. (H-4): The polymerization was carried out in the same manner as in (H-1), except that the stirring number of the multistage reactor was changed. The weight average particle diameter of the rubber of the obtained rubber-modified styrene resin was 1.8 μm, and the reduced viscosity ηsp / C was 0.60.

[0022]

Example 1 Rubber-modified styrene resin (H-1) 100
The organic polysiloxane (S-1) is added in an amount of 0.005 parts by weight.
After adding 5 parts by weight and mixing with a drum blender, the mixture was kneaded with an extruder and formed into pellets. Further, as a halogen-based flame retardant, tristribromoneopentyl phosphate 6.0.
A part by weight (manufactured by Daihachi Chemical Co., Ltd., trade name: CR900) and 1.0 part by weight of antimony trioxide were added, mixed by a drum blender, kneaded by a twin screw extruder, and pelletized. The obtained pellet was molded by an injection molding machine to obtain a test piece.
Table 1 shows the evaluation results.

[0023]

Example 2 Rubber-modified styrene resin (H-1) 100
The organic polysiloxane (S-1) is added in an amount of 0.005 parts by weight.
One part by weight was added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0024]

Example 3 Rubber-modified styrene resin (H-2) 100
The organic polysiloxane (S-1) is added in an amount of 0.005 parts by weight.
5 parts by weight were added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0025]

Example 4 Rubber-modified styrene resin (H-3) 100
The organic polysiloxane (S-1) is added in an amount of 0.005 parts by weight.
5 parts by weight were added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0026]

Example 5 Rubber-modified styrene resin (H-4) 100
The organic polysiloxane (S-1) is added in an amount of 0.005 parts by weight.
5 parts by weight were added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0027]

Example 6 Rubber-modified styrene resin (H-1) 100
The organic polysiloxane (S-1) is added in an amount of 0.005 parts by weight.
After adding 5 parts by weight and mixing with a drum blender, the mixture was kneaded with an extruder and formed into pellets. Furthermore, as a phosphorus-based flame retardant,
After adding 6.0 parts by weight of triphenyl phosphate and mixing with a drum blender, the mixture was kneaded with a twin-screw extruder and pelletized. The obtained pellets are ordered by injection molding machine,
A test piece was obtained. Table 1 shows the results.

[0028]

Example 7 Rubber-modified styrene resin (H-1) 100
To the parts by weight, the organic polysiloxane (S-2) was added in an amount of 0.00
After adding 5 parts by weight and mixing with a drum blender, the mixture was kneaded with an extruder and formed into pellets. Further, the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0029]

Comparative Example 1 Rubber-Modified Styrenic Resin (H-1) 100
The halogen-based flame retardant was evaluated in parts by weight in the same manner as in Example 1. Table 1 shows the evaluation results. When the rubber-modified styrene-based resin does not contain an organic polysiloxane, the flammability is good but sufficient impact strength cannot be obtained.

[0030]

Comparative Example 2 Rubber-Modified Styrenic Resin (H-1) 100
To the parts by weight, the organic polysiloxane (S-1) is added in an amount of 0.01%.
0 parts by weight were added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.
When the addition amount of the organic polysiloxane is large, the composition shows good impact strength but does not clear the flammability.

[0031]

Comparative Example 3 Rubber-Modified Styrenic Resin (H-1) 100
To the parts by weight, the organic polysiloxane (S-1) is added in an amount of 0.01%.
After adding 0 parts by weight and mixing with a drum blender, the mixture was kneaded with an extruder and formed into pellets. Further, as a halogen-based flame retardant, tristribromoneopentyl phosphate 9.0
A part by weight (manufactured by Daihachi Chemical Co., Ltd., trade name: CR900) and 1.5 parts by weight of antimony trioxide were added, mixed by a drum blender, kneaded by a twin screw extruder, and pelletized. The obtained pellet was molded by an injection molding machine to obtain a test piece.
Table 1 shows the evaluation results. By increasing the amount of the flame retardant added, the flammability is cleared but sufficient impact strength cannot be obtained.

[0032]

Comparative Example 4 Rubber-Modified Styrenic Resin (H-1) 100
To the parts by weight, an organic polysiloxane (S-3) was added in an amount of 0.00
5 parts by weight were added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results. When an organic polysiloxane having a high viscosity is used, sufficient impact strength cannot be obtained.

[0033]

Comparative Example 5 Rubber-Modified Styrenic Resin (H-1) 100
The organic polysiloxane (S-4) is added in an amount of 0.00 parts by weight.
5 parts by weight were added, and the halogen-based flame retardant was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results. When an organic polysiloxane having a high phenyl content is used, sufficient impact strength cannot be obtained.

[0034]

[Table 1]

[0035]

The flame-retardant styrene resin composition of the present invention has excellent balance of impact resistance, gloss and rigidity, and also has excellent flame-dropping properties with a smaller amount of flame retardant. Has characteristics. Because of these characteristics, it is ideal for home appliance parts, office equipment parts, etc.
These industries play a major role.

Claims (3)

[Claims] (A) a rubber-modified polystyrene resin,
(B) 0.001 to 0.005% by weight of an organic polysiloxane having a structural unit represented by the following formula (1) of 90% or more.
And (C) an ignition-melt-drop flame-retardant styrene resin composition comprising a halogen-based and / or phosphorus-based flame retardant. Embedded image 2. The flame-retarded flammable styrene resin composition according to claim 1, wherein the organic polysiloxane is polydimethylsiloxane. 3. The solution viscosity of the organopolysiloxane at 25 ° C. is 50 to 400 centistokes.
Or a flame-retarded styrene-based resin composition according to 2 above.