JPH03252443A - Fire-resistant resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject fire-resistant resin composition excellent in impact resistance, having heat resistance and excellent in heat stability during molding process by blending a specified rubber modified polystyrene-based resin with a specified brominated polystyrene and arbitrarily antimony trioxide. CONSTITUTION:A resin composition composed of (A) 100 pts.wt. rubber modified polystyrene-based resin obtained from styrene and a rubbery polymer (suitably polybutadiene or butadiene-styrene copolymer), containing the rubbery polymer in a state of dispersed particles having 0.3-5mum particle size and having 3-18wt.% rubber content, 2-5 ratio of gel content to the rubber content and 8-12 swelling index, (B) 3-20 pts.wt. brominated polystyrene (e.g. polytribromostyrene) having 1500-15000, preferably 2000-12000 weight-average molecular weight and 68-72%, preferably 68-70% bromine content and (C) 0-10 pts.wt., preferably 1-5 pts.wt. antimony trioxide.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a styrenic resin composition that has excellent impact resistance, H flammability, good heat resistance, and excellent molding stability. It is.

[Problem B to be solved by conventional technology and the invention] Styrenic resins are inexpensive and have many properties such as excellent impact resistance, heat resistance, mechanical properties, electrical properties, and moldability. Therefore, it is widely used in large quantities in household electrical appliances, office equipment, household goods, etc. However, since styrene resins are easily flammable, they are subject to various regulations regarding flame retardancy, such as UL standards, and are subject to many restrictions on use.

Flame retardant of styrenic resins is mainly achieved by adding compounds containing halogens, phosphorus, etc., and flame retardant aids such as antimony trioxide. Although the desired flame retardance can be obtained by blending with , it often has a negative effect on other physical properties. In addition, in recent years, with the spread of large molded products such as large TV housings and computer housings, in addition to flame retardant and impact resistance, especially those with high practical impact strength, such as those with good heat resistance and molded products. There is a strong demand for molding materials with excellent specific thermal stability.

BACKGROUND ART Conventionally, it has been known to produce a flame-retardant resin composition by blending brominated polystyrene as a flame retardant with a thermoplastic resin.

In published patent No. 62-501153, the number of bromine atoms is 1 per aromatic ring of brominated polystyrene.
．． It has been disclosed that a flame retardant resin composition can be obtained by blending a thermoplastic resin with a bromine number of 2.5 to 2.5 per aromatic ring of brominated polystyrene. There is no specific description of cases where the value is greater than 5.

In addition, in published patent No. 1983-501427,
It is disclosed regarding the production of brominated polystyrene, and it is stated that in the case of poly-trifllomostyrene, those with lower weight average molecular weights, that is, up to Li2O, have good compatibility in blending with polyphenylene ether. However, there is no description of rubber-modified polystyrene resin.

[Means for Solving the Problems] In view of the above circumstances, the present inventors have developed a styrenic resin composition that has excellent impact resistance, flame retardancy, good heat resistance, and excellent molding stability. As a result of intensive studies to obtain this, it was discovered that this can be achieved by blending a halogen-containing compound with a specific structure into a resin having a specific composition, or by blending antimony trioxide into the blend, and the present invention has been made. It has been completed.

That is, in the present invention, the rubbery polymer is dispersed in a size of 0.3 to 5 microns, the rubber content is 3 to 18% by weight, and the ratio of gel content to rubber content is 2 to 5. Rubber-modified polystyrene resin (
A) 100 parts by weight, weight average molecular weight 1.500-15,
000, relates to a flame-retardant resin composition comprising 3 to 20 parts by weight of brominated polystyrene (B) having a bromine content of 68% to 72% by weight, and 0 to 10 parts by weight of antimony trioxide (C).

The present invention will be explained in detail below.

The rubber-modified polystyrene resin (A) used in the present invention is
It can be produced by conventional bulk polymerization, bulk-suspension polymerization, etc. using styrene and a rubbery polymer. Examples of styrene include styrene, α-substituted styrene 1 such as α-methylstyrene, vinyltoluene, m-chlorostyrene, P
Examples include nuclear-substituted styrenes such as -chlorostyrene and P-methylstyrene, and one or more of these may be used. Styrene is most preferred. Examples of rubbery polymers include natural rubber, polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, polychloroprene, acrylic rubber, and ethylene-styrene copolymer.
Examples include propylene rubber, ethylene-propylene-diene monomer rubber, and ethylene-vinyl acetate copolymer. Polybutadiene and butadiene-styrene copolymers are preferred.

The rubbery polymer in the rubber-modified polystyrene resin (A) used in the present invention needs to be dispersed in a size of 0.3 to 5 microns. The size of the rubbery polymer is 0.3
If the particle size is less than microns, the impact strength, especially the practical impact strength, the falling hammer impact strength, will be greatly reduced, and it will be difficult to make it flame retardant, so a large amount of flame retardant will be required, resulting in a decrease in physical properties and an economic disadvantage. Moreover, when the diameter is larger than 5 microns, the impact resistance, especially the practical impact strength, such as the drop impact strength, decreases considerably.

The rubber content of the rubber-modified polystyrene resin (A) is 3 to 18
It is necessary that the amount is % by weight. If the amount of rubber is less than 3% by weight, the impact strength will decrease, and if it is more than 18% by weight, properties such as iI flammability, light resistance, fluidity, rigidity, and thermal stability will deteriorate, which is not preferable.

It is necessary that the ratio of the gel content to the rubber amount of the rubber-modified polystyrene resin (A) is in the range of 2 to 5. If the ratio of gel content to rubber content is less than 2, the impact strength will decrease, which is undesirable, and if it is greater than 5, a large amount of flame retardant will be required, resulting in a decrease in impact resistance and an economic disadvantage.

The swelling index of the rubber modified polystyrene resin (A) is 8 to 1.
It is necessary to be within the range of 2. If the swelling index is less than 8, flame retardance will not be achieved, and a large amount of flame retardant will be required, resulting in a decrease in impact resistance and an economic disadvantage. Also, the swelling index is 12
If it is larger, the impact strength decreases, making it impossible to obtain a well-balanced flame-retardant resin composition.

The molecular structure of the brominated polystyrene (B) (hereinafter abbreviated as flame retardant) used in the present invention is as shown below.

X; Natural number (number of bromine) %~70% by weight
It is. In addition, the weight average molecular weight is 1,500 to 15,0
00, preferably 2.000 to 1.2.000.

The amount used is 3 to 20 parts by weight per 100 parts by weight of the rubber-modified polystyrene resin. If the weight average molecular weight of the flame retardant is less than 1,500, the glass transition temperature will be low, and when mixed with rubber-modified polystyrene resin to make a flame retardant resin composition, the heat resistance temperature will be lowered, which is undesirable. When the molecular weight exceeds 15,000, the impact resistance, especially the practical impact strength, the impact strength of the stone drop, is significantly reduced.

Although the reason is not clear, it is presumed that it is related to the compatibility between the specific rubber-modified polystyrene resin (A) and the specific flame retardant. Furthermore, if the flame retardant is less than 3M parts per 100 parts by weight of the rubber-modified polystyrene resin, the necessary flame retardancy cannot be obtained, and if it exceeds 20 parts by weight, it is only economically disadvantageous. As a result, the impact resistance, especially the practical impact strength, such as the drop impact strength, is greatly reduced.

In the present invention, the above-mentioned rubber-modified polystyrene resin (A) 1
Even with only 3 to 20 parts by weight of the above-mentioned flame retardant, a molding material having good flame retardancy and impact resistance as well as good thermal stability during molding can be obtained.

Furthermore, in the present invention, it is preferable that antimony trioxide (C) is present as a flame retardant auxiliary agent since the amount of expensive flame retardant added can be reduced. The amount of antimony dioxide (C) added is 0 to 10 parts by weight. The amount of antimony trioxide used as a flame retardant aid varies depending on the UL-94 combustion class, but from an economical point of view it is preferably 1 to 5 parts by weight. If the amount of antimony trioxide exceeds 10 parts by weight, impact resistance decreases, which is not preferable.

The method for producing a flame retardant resin composition of the present invention includes adding a flame retardant and antimony trioxide (
By blending C). There are no particular restrictions on the blending method, and methods include methods using a tumbler mixer, super mixer, bar/bury mixer, kneader roll, single screw extruder, twin screw extruder, etc.

Other flame retardants and additives can be added to the flame-retardant resin composition of the present invention, if necessary, within a range that does not impair the object of the present invention. Various additives include plasticizers, lubricants, stabilizers, ultraviolet absorbers, fillers, reinforcing agents, colorants, and the like.

[Effects of the Invention] The flame-retardant resin composition of the present invention is a styrene-based resin composition that has excellent impact resistance, flame retardancy, good heat resistance, and excellent thermal stability during molding. It is extremely useful industrially, especially as a housing material for office equipment and electrical equipment.

[Example code] The present invention will be described below with reference to Examples and Comparative Examples.

Evaluation of the flame-retardant resin composition was performed by the following method. Pellets were used for melt flow rate tests, and injection molded specimens were used for other tests.

・Izotsu impact strength ASTM-D256. Test piece thickness 'j 6.4 mm, with notch, impact strength 15011II 11 square, thickness 3n+n+, using a missile (R = 3/4 inch) on a flat plate molded product of one bin gate, and the load placed on the missile and Distance the missile falls (
Calculate the fracture energy at the point where the molded product breaks by changing the distance from the tip of the missile to the surface of the molded product.

- Melt flow rate 150-R1133, temperature 200°C, load 5kg, tensile strength measured according to ASTM-0638.

·stretch Measured according to ASTM-0638.

・Heat deformation temperature ASTM -0648, specimen thickness 6.4 mm, no annealing, bending stress 18.6 kg/cm2 ・Flammability (UL94) Specimen thickness 1/8.1/12 I, V-O or V
Determine -2.

・Thermal stability test Toshiba Machine 1580-A, cylinder temperature 230'' C1 mold temperature 60°C, residence time 10 minutes, after 20 minutes molding, 3rd shot color chip (90mm x 50mm
The condition of the baked material (X2.5nv thickness) was comparatively observed, and the following criteria were followed.

・Particle size of rubbery polymer Coulter Counter (Coulter Counter RTI-
Type II), using a mixed electrolyte of dimethylformamide and ammonium thiocyanate, resin pellets 2~
Put 4 grains in about 5 ml of dimethylformamide and put about 2~
Leave for 5 minutes. Next, the dimethylformamide dissolved content is measured as an appropriate particle concentration, and the 50% median diameter is defined as the average particle diameter.

- Add 20ml of toluene to a resin with a swelling index of 1g and shake vigorously for 1 hour to dissolve or swell. Next, after the gel is sedimented using a centrifuge, the supernatant liquid is separated by decantation, and the sedimented gel is weighed. The toluene-swollen gel thus obtained is dried at 160° C. and normal pressure for 45 minutes, then dried under reduced pressure of 3 to 5 mmHg for 15 minutes, and weighed in a desiccator in a cooling layer. The swelling index is expressed as the quotient of the weight of the toluene-swollen gel divided by the weight of the dry gel.

, Rubber amount Rubber modified polystyrene resin is compressed to 20
The film was made into a thin film at 0″C, and the film was measured at 1601 with an infrared spectrophotometer (Hitachi, EPI, G3).
Measure the absorbance ratio of the absorption bands at cm-' and 967 cm-', and calculate the amount of rubber using the calibration curve prepared in advance.
Set.

・Weight average molecular weight of brominated polystyrene The weight average molecular weight of brominated polystyrene is 1.500 to 15.000, preferably 2,000 to 12.000 in terms of the molecular weight of a styrene compound polymer determined by molecular weight measurement using gel permeation chromatography. desirable.

・Measuring instrument manufacturer and model % formula % Solvent: Tetrahydrofuran Temperature: 38°C Concentration: 20■/20d Solvent (Polymerization of rubber-modified polystyrene resin) Polymerization of rubber-modified polystyrene resin used in Examples and Comparative Examples , 100 parts of a solution of polybutadiene dissolved in styrene monomer, 5 parts of ethylbenzene, 1.1-bis(b-butylperoxy)33.5-1-limethylcyclohexane 0.0
After adding 5 parts to prepare a polymerization raw material solution, the raw material solution was continuously fed into a continuous three-stage polymerization machine to perform polymerization. Each polymerizer has a capacity of 1.21 mm and is equipped with stirring blades. The polymerization temperature was varied between 105 and 145°C, and after polymerization was carried out until the solid content reached 80% at the exit of the final polymerizer, it was sent to a devolatilization device under heating and vacuum to remove unreacted styrene monomer and ethylhenzene. Then, the strands are pulled from the die, cooled in water, and then cut into pellets. The content of rubbery substances in the pellets was measured, and the rubber content was 10% and the particle size was 2.
μ, gel content/rubber content ratio 3. A rubber-modified polystyrene resin (H-1) having a swelling index of 10 was obtained. H-2 to H-10 were polymerized by a similar method. Table 1 describes the compositions of rubber-modified polystyrene resins H-1 to H-10.

Margins below Table 1 Table 2 (Note) Above structural formula (halogen-containing compound) Table 2 shows the properties of various halogen-containing compounds used in Examples and Comparative Examples.

- B - B-6 TBA monomer (tetrabromobisphenol A) Example 1 Rubber-modified polystyrene resin H-1, halogen-containing compound β-1, antimony trioxide and others were mixed in a drum blender in the proportions shown below, The mixture was kneaded and pelletized at 220''C using a 35mmφ vented twin-screw extruder.

Part by weight Rubber-modified polystyrene resin (H-1) 100 Halogen-containing compound (B-1) 16 Antimony trioxide 4 Tin-based heat stabilizer
0.5 Ethylene bisstearamide 0.5 The obtained pellets were injection molded at a cylinder temperature of 220°C and a mold temperature of 60°C.
Various physical properties were measured. The results are shown in Table 3.

Examples 2 to 5 A pellet was obtained by melt-kneading in the same manner as in Example 1, except that the rubber-modified polystyrene resin, halogen-containing compound, and antimony trioxide in Example 1 were changed as shown in Table 3. The evaluation results are shown in Table 3.

Comparative Example 1.2 Pellets were obtained by melt-kneading in the same manner as in Example 1, except that a halogen-containing compound having a weight average molecular weight of 600.000 was used in place of the halogen-containing compound in Example 1. The evaluation results are shown in Table 3.

Comparative Examples 3 to 6 Rubber modified polystyrene resin H-1 in Example 1 was
A pellet was obtained by melt-kneading in the same manner as in Example 1, except that H-5 was used in Comparative Example 3, H-6 in Comparative Example 4, H-7 in Comparative Example 5, and H-8 in Comparative Example 6. . The evaluation results are shown in Table 4.

Comparative Example 7 Pellets were obtained by melt-kneading in the same manner as in Example 1, except that the amount of antimony trioxide in Example I was changed to 16 parts by weight. The evaluation results are shown in Table 4.

Comparative Example 8 Rubber modified polystyrene resin H-1 of Example 1 was replaced with H
-5, pellets were obtained by melt-kneading in the same manner as in Example 1, except that B-4 was used in place of halogen-containing compound B-1. The evaluation results are shown in Table 4.

Comparative Example 9 Rubber modified polystyrene resin H-1 of Example 1 was replaced with H
Pellets were obtained by melt-kneading in the same manner as in Example 1, except that B-9 was used instead of halogen-containing compound B-1 and antimony trioxide was not added. The evaluation results are shown in the fourth
Shown in the table.

Comparative Example 10 Rubber-modified polystyrene resin H-1 of Example 1 was replaced with H
-10, halogen-containing compound B-1 was replaced with B-6, and the blending amount of the flame retardant aid was changed, but melt-kneading was carried out in the same manner as in Example 1. The evaluation results are shown in Table 4.

Comparative Example 11 Rubber modified polystyrene resin H-1 of Example 1 was replaced with H
Melt-kneading was carried out in the same manner as in Example 1 except that -11 was used. The evaluation results are shown in Table 4.

Margin below

Claims (1)

[Scope of Claims] 1. (A) (a) The rubbery polymer is dispersed in a size of 0.3 to 5 microns, and (b) The amount of rubber is 3 to 18% by weight (
c) 100 parts by weight of a rubber-modified polystyrene resin having a gel content to rubber content ratio in the range of 2 to 5, and (d) a swelling index of 8 to 12, (B) a weight average molecular weight of 1,50
0 to 15,000, 3 to 20 parts by weight of brominated polystyrene with a bromine content of 68% to 72% by weight, and (
C) A flame-retardant resin composition comprising 0 to 10 parts by weight of antimony trioxide. 2. The flame-retardant resin composition according to claim 1, wherein the brominated polystyrene is tribromopolystyrene.