KR20020024638A - Fire retardant styrene based resin composition having superior impact resistance - Google Patents

Abstract

PURPOSE: A flame retardant styrene-based resin composition is provided, which is excellent in impact resistance at a low temperature by using a styrene-based graft copolymer with a specific structure and a block copolymer with a specific structure containing styrene and diene-rubber in combination. CONSTITUTION: The styrene-based resin composition comprises 100 parts by weight of a styrene-based resin which comprises 85-99.5 wt% of a styrene-based graft copolymer and 0.5-15 wt% of a radial structured block copolymer containing styrene and diene-rubber; 4-25 parts by weight of a halogen-based flame retardant; and 0.5-10 parts by weight of antimony trioxide. The styrene-based graft copolymer comprises 3-30 wt% of a soft component particle having the cis 1,4-bond in butadiene chain of diene-based rubber by 70 wt% or more; and 70-97 wt% of styrene-based resin matrix. Preferably the soft component particle is polybutadiene or styrene-butadiene copolymer, and the glass transition temperature is less than -30 deg.C.

Description

Flame-retardant styrene-based resin composition excellent in impact resistance {FIRE RETARDANT STYRENE BASED RESIN COMPOSITION HAVING SUPERIOR IMPACT RESISTANCE}

[Industrial use]

The present invention relates to a styrene resin composition, and more particularly, by using a styrene graft copolymer made of a rubber component having a specific structure and a block copolymer made of a specific structure made of styrene and a diene rubber in combination with impact resistance, particularly at a low temperature. The present invention relates to a flame retardant styrene resin composition excellent in impact resistance that has greatly improved impact resistance.

[Prior art]

Styrene-based resins represented by impact-resistant polystyrene are used in various industrial fields including home appliances and office equipment parts because of their excellent moldability, rigidity, and electrical properties. In particular, recently, it is mainly used for a television housing.

Styrene-based resins have burned properties despite excellent processability and physical properties, and thus have raised safety issues. Accordingly, studies have been made to impart flame retardancy to styrene resins, and recently, flame retardant styrene resins using halogen compounds have been widely used.

As a flame retardant method of the impact resistant polystyrene resin, a method of applying decabromodiphenyl oxide is disclosed in European Patent No. 0723992A1. The flame retardant provides a resin composition which is very excellent in terms of flame retardancy and physical properties, but has the disadvantage of not only generating dioxins upon combustion but also having poor weather resistance. In order to solve this problem, a flame retardant resin composition using a brominated epoxy resin and a brominated imide resin (Japanese Patent Laid-Open No. 193-125238) and a flame retardant resin composition using a decabromodiphenylethane and a brominated epoxy resin in combination (Japanese Patent Publication No. 1996-092445). As such, by using two or more flame retardants together, various physical properties could be balanced.

As mentioned above, until recently, research on flame-retardant styrene-based resins has been focused on finding a way to balance physical properties and flame retardancy. Styrene-based resins have been used all over the world because of their excellent formability. In recent years, the thinning of home appliances and other office equipment and the cost reduction have been rapidly progressed. However, the impact resistance of conventional resins has not reached the level required by such super-large, thin-film products. Accordingly, there is a great need for a method capable of improving the impact resistance of flame retardant styrene resins.

The most common method of improving the impact resistance of flame retardant styrene resins is to add an impact modifier, and a method of adding a block copolymer of styrene-butadiene is widely used. Other new ways to improve impact resistance have been announced. Japanese Patent Laid-Open No. 1999-29687 discloses a method in which an ethylene-methyl methacrylate copolymer is added to improve the flame retardancy and the impact strength of the resin. However, this method does not provide a comparison with other impact modifiers, so its superiority cannot be confirmed. In addition, a method of improving impact resistance by controlling the particle size distribution of rubber particles of impact-resistant polystyrene resin itself is disclosed in Japanese Patent Laid-Open No. 1999-343373, which has a resin having large diameter particles and small diameter particles. By using resin together, it is a method which can maintain the outstanding impact resistance after flame retardation. That is, the method which can improve impact resistance can be broadly divided into the method of adding an impact modifier, and the method of modifying styrene resin itself. Although various methods have been proposed as described above, a more effective method for improving the impact resistance of the flame retardant styrene-based resin, particularly the low temperature impact resistance, is continuously required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic resin composition capable of improving the impact resistance, particularly the low temperature impact resistance, of a flame retardant styrene resin in consideration of the problems of the prior art.

[Means for solving the problem]

The present invention to achieve the above object

a) the content of cis 1,4-bond in the butadiene chain in the diene rubber is 70

3 to 30 parts by weight of the soft component particles of at least% by weight, 70

Styrene-based styrene resin to form a matrix of from 97 parts by weight

85 to 99.5 parts by weight of a graft copolymer,

b) radial block copolymers composed of styrene and diene rubber

0.5 to 15 parts by weight,

c) with respect to 100 parts by weight of the styrene-based resin consisting of a) and b)

4 to 25 parts by weight of halogen-based flame retardant, and

d) 0.5 to 10 parts by weight of antimony trioxide

It provides a flame retardant styrene resin composition comprising a.

Hereinafter, the present invention will be described in detail.

[Action]

The inventors have studied to achieve the above object of the invention, and as a result, the impact-resistant polystyrene resin including a diene rubber made of polybutadiene having a specific structure and a block copolymer of a specific structure made of styrene and a diene rubber are simultaneously applied. When it was confirmed that the impact resistance, particularly low temperature impact resistance was significantly improved, according to the resin composition as described below was obtained a thermoplastic resin excellent in impact resistance, particularly low temperature impact resistance as well as excellent flame resistance and moldability.

Hereinafter, each component used for this invention is demonstrated in detail.

The a) styrenic graft copolymer of the present invention is a polymer obtained by dispersing a rubbery polymer in the form of particles on a matrix of a vinyl aromatic polymer. As a polymerization method, bulk polymerization, suspension polymerization, and emulsion polymerization are all used. Can be. Among these, block polymerization is the most preferable. At the time of bulk polymerization, the rubbery polymer is dissolved in a vinyl aromatic monomer, followed by stirring, and polymerization is performed by adding a polymerization initiator.

The a) styrene graft copolymer includes a diene rubber (hysis butadiene) having a cis 1,4-bond of 70% by weight or more in the butadiene chain portion of the diene rubber. It is preferable that the content of the cis 1,4-bond in the butadiene chain in the soft component particles is 90% by weight or more. In the case of butadiene (low cis butadiene) having a cis 1,4-bond of less than 70% by weight, the effect of improving impact resistance is insignificant. The glass transition temperature (T _g ) of the soft component particles (rubber polymer) used herein is preferably -30 ° C or lower. If it exceeds -30 ℃, impact resistance is lowered.

Examples of the vinyl aromatic monomers include styrene, as well as nucleoalkyl substituted styrene such as paramethyl styrene, 2,4-dimethyl styrene and ethyl styrene, and alpha alkyl substituted styrene such as alpha methyl styrene and alpha methyl paramethyl styrene. You may use together or more types. Moreover, as said soft component particle | grain (rubber phase polymer), a polybutadiene, a styrene-butadiene copolymer, a butadiene-isoprene copolymer, etc. are preferable, A polybutadiene and a styrene-butadiene copolymer are more preferable. The content of the rubbery polymer of the styrene graft copolymer is 3 to 30 parts by weight, and generally 4 to 15 parts by weight is preferable. In addition, the particle diameter of the rubbery particles is preferably 0.5 to 6 m. In the flame retardant styrene resin composition, a) the styrenic graft copolymer preferably includes 85 to 99.5 parts by weight.

The b) block copolymer is a radial block copolymer composed of a vinyl aromatic monomer and a diene compound. Styrene is mainly used as a vinyl aromatic monomer, and butadiene, isoprene, or two monomers may be used together as a diene compound. That is, it is preferable that the said b) block copolymer is a copolymer of styrene and butadiene.

The molecular structure of the block copolymer may be linear, branched, radial or a combination of these structures but exhibits a synergistic impact resistance when having a radial structure. The number average molecular weight of the block copolymer is 5,000 to 600,000 and preferably 10,000 to 500,000. The b) block copolymer in the flame retardant styrene resin composition preferably includes 0.5 to 15 parts by weight.

The c) halogen flame retardant used in the present invention is one or more selected from among the organic halogen-based compounds decabromodiphenyl oxide, decabromodiphenylethane, tetrabromobisphenol A, brominated epoxy resin, brominated triazine compound, Or a brominated imide compound. Two or more compounds may be used in combination. Examples of the organic halogen compound include an organic chlorine compound and an organic bromine compound. Among these, organic bromine compounds are excellent in imparting flame retardancy, and examples thereof include brominated phenol resins, brominated diphenyl oxide resins, brominated epoxy resins, and brominated imide resins. C) The halogen-based flame retardant may include 4 to 25 parts by weight based on 100 parts by weight of the styrene resin comprising a) a styrene graft copolymer and b) a block copolymer.

The antimony trioxide d) is a flame retardant aid that causes a flame retardant synergy with the halogen-based flame retardant. The d) antimony trioxide preferably includes 0.5 to 10 parts by weight based on 100 parts by weight of the styrene resin comprising a) a styrene graft copolymer and b) a block copolymer.

It is preferable that the flame-retardant styrene resin composition further comprises at least one additive selected from the group consisting of an antioxidant, a heat stabilizer, a lubricant, an antidropping agent, an inorganic additive, and a pigment.

The present invention will be described in more detail through the following Preparation Examples and Examples. However, an Example is for illustrating this invention and this invention is not limited only to these.

[Production example]

An example of the preparation of the rubber-reinforced styrenic graft copolymer (HIPS) is as follows.

(Manufacture example 1 of HIPS)

10.5% by weight of cisis polybutadiene (95% by weight of cis 1,4-bond), 74.2% by weight of styrene, 15.0% by weight of ethylbenzene, 0.27% by weight of alphamethylstyrene dimer, tertiarybutylperoxy isopropyl carbonate (tert- Butylperoxy isopropyl carbonate) mixed with 0.03% by weight of the solution was continuously polymerized in a four-stage reactor equipped with a stirrer. The first stage reactor was polymerized at 190 rpm of stirring water, a temperature of 126 ° C., the second stage reactor was 50 rpm, 133 ° C., the third stage reactor was 20 rpm, 140 ° C., and the fourth stage reactor was 20 rpm, 155 ° C. A 73% by weight of solid solution from the final reactor was passed through a devolatilizer to remove unreacted monomers and solvents. The rubber content of the obtained rubber-reinforced styrenic graft copolymer (HIPS-1) was 12.1 wt%, and the weight average molecular particle diameter of the rubber was 1.5 μm.

(Manufacture example 2 of HIPS)

A copolymer (HIPS-2) was prepared in the same manner as in HIPS Preparation Example 1 except that the cis 1,4-linkage of the polybutadiene was 80% by weight.

(Manufacture example 3 of HIPS)

A copolymer (HIPS-3) was prepared in the same manner as in Preparation Example 1 of HIPS, except that the cis 1,4-linkage of the polybutadiene was 30% by weight.

As the block copolymer of the diene rubber and styrene, LG414D having a radial structure and LG503D having a linear structure were used. Both products are LG Chemical Co., Ltd. and are block copolymers of styrene and butadiene.

As flame retardant additives, a halogen flame retardant, decabromodiphenyl oxide (DECA) and antimony trioxide (Sb ₂ O ₃ ) were used.

[Examples and Comparative Examples]

The above components were formulated according to the weight ratios given in Table 1 below. In the present invention, 0.5 parts by weight of polyethylene (molecular weight 2,000), 0.6 parts by weight of zinc stearic acid, 0.5 parts by weight of heat stabilizer, and 0.05 parts by weight of antidropping agent were added in addition to the above components. The blended resin composition was uniformly mixed with a Henschel mixer and then extruded with a twin screw extruder to obtain a resin composition in pellet form. The physical specimens were obtained by injection molding and the results of physical properties are shown in Table 1 below.

Physical properties were measured according to ASTM standards, and flame retardancy was determined according to UL-94. Impact strength was measured with 1/8 "notched specimens and fluidity was measured under conditions of 200 ° C / 5 kg. Tensile strength and flexural strength were measured at 5 cm / min and 1.5 cm / min, respectively. Intensity was measured at -10 ° C.

TABLE 1

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Content by component (parts by weight) HIPS-1 100 - - 100 - HIPS-2 - 100 - - - HIPS-3 - - 100 - 100 LG414D 5 5 5 - - LG503D - - - 5 5 DECA 15 15 15 15 15 Sb ₂ O ₃ 5 5 5 5 5 Properties Impact strength (kg ?? cm / cm) Room temperature (23 ℃) 10.0 10.1 9.5 9.4 9.4 Impact Strength (kg ?? cm / cm) Low Temperature (-10 ℃) 7.0 6.9 6.0 6.1 5.9 Fluidity (g / 10 min) 7.0 7.1 6.8 7.2 7.0 Tensile Strength (kg / cm ² ) 256 250 249 245 246 Flexural Strength (kg / cm ² ) 433 439 435 430 437 Flame Retardant (1/6 ") V-0 V-0 V-0 V-0 V-0

As shown in the above Examples and Comparative Examples, the flame retardant styrene resin composition of the present invention has a specific structure comprising a rubber-reinforced styrene resin and styrene-butadiene containing a specific amount of polybutadiene rubber having a polybutadiene structure of a specific structure. By using a block copolymer together, impact resistance especially the low temperature impact resistance could be improved significantly.

Claims (7)

a) the content of cis 1,4-bond in the butadiene chain in the diene rubber is 70% by weight or less; 3 to 30 parts by weight of merchant soft component particles, 70 to 97 parts by weight Styrene graft copolymer 85 to styrenic resin form a matrix 99.5 parts by weight, b) from 0.5 to radial block copolymer composed of styrene and diene rubber 15 parts by weight, c) halogen based on 100 parts by weight of the styrene-based resin comprising a) and b) 4 to 25 parts by weight of a flame retardant, and d) 0.5 to 10 parts by weight of antimony trioxide Flame retardant styrene resin composition comprising a. The method of claim 1, A flame retardant styrene resin composition wherein the soft component particles of the a) styrene graft copolymer are polybutadiene and styrene-butadiene copolymer. The method according to claim 1 or 2, A flame retardant styrene resin composition having a content of cis 1,4-bond in the butadiene chain in the soft component particles of 90 wt% or more. The method of claim 2, The flame retardant styrene resin composition whose glass transition temperature of the said soft component particle | grains is -30 degrees C or less. The method of claim 1, A flame retardant styrene resin composition wherein the block copolymer of b) is a copolymer of styrene and butadiene. The method of claim 1, The flame retardant styrene resin composition wherein the halogen flame retardant of c) is decabromodiphenyl oxide, decabromodiphenylethane, tetrabromobisphenol A, brominated epoxy resin, brominated triazine compound, or brominated imide compound. The method of claim 1, The flame retardant styrene resin composition further comprises one or more additives selected from the group consisting of antioxidants, heat stabilizers, lubricants, anti drip agents, inorganic additives, and pigments.