JPH04149265A - Flame-retardant resin composition having excellent moldability - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a resin composition with excellent flame retardancy.

More specifically, the present invention relates to a flame-retardant styrenic resin composition that does not contain a halogen compound.

[Issues that traditional technology and inventions try to solve] HIPS
Rubber-modified vinyl aromatic resins, represented by , have excellent moldability and dimensional stability, as well as impact resistance, rigidity, and electrical insulation properties, so they are used in home appliance parts, OA equipment parts, and other applications. It has come to be used in a wide variety of fields.

For plastic materials used in such fields in recent years,
Due to safety issues, the demand for flame retardant properties is increasing.
Various flame retardant standards have been established. Various methods have been devised to impart flammability to such easily flammable resins. A method has been adopted in which antimony oxide is added to the resin. Nuclear bromine monovalent aromatic compounds such as decabromodiphenyl ether, tetrabromobisphenol A, and brominated phthalimide are known as bromine compounds, but the method of adding these flame retardants does not provide excellent flame retardancy. However, there were problems such as a decrease in impact strength and heat distortion temperature, and in some cases, the flame retardant could bleed out onto the surface of the resin molded product, deteriorating the appearance of the molded product. Furthermore, during resin molding, due to thermal decomposition of halogen compounds,
There were problems such as generating gases that were toxic to the human body and corroding the molds and screws.

For this reason, methods of W fuming without using halogen compounds are being considered. As such a method, a method of adding a hydrated metal compound such as aluminum hydroxide or magnesium hydroxide to the resin is known, but in order to obtain sufficient flame retardancy, it is necessary to add a large amount of the hydrated metal compound. This has the disadvantage that the original properties of the resin are lost.

On the other hand, as a method that does not use such hydrated metal compounds,
Flame-retardant resin composition formed by blending a phenol aldehyde resin, an organic nitrogen compound, and an organic phosphorus compound with a thermoplastic resin (U.S. Pat. No. 4,632.946), ABS
A flame-retardant resin composition (Japanese Patent Application Laid-Open No. 61-291643) is disclosed, which is a resin containing red phosphorus, melamine, and a thermally crosslinkable curable resin. However, this method requires a large amount of various additives, which has the problem of impairing the original properties of the resin.

On the other hand, US Pat. No. 4,461,874 discloses a flame-retardant resin composition comprising polyphenylene ether, styrene resin, and red phosphorus.

Although the above resin composition is a useful flame-retardant resin material that does not use a halogen compound, it contains a large amount of polyphenylene ether with low fluidity, so there is a problem that the moldability of the resin composition is poor.

[Means for Solving the Problems] The present inventors have conducted intensive studies to improve the fluidity of a rubber-modified vinyl aromatic resin represented by HIPS, and a flame-retardant resin made of polyphenylene ether and red phosphorus. ,
We have discovered that a resin composition consisting of a rubber-modified vinyl aromatic resin with a specific structure, a small amount of polyphenylene ether, red phosphorus, and mineral oil added as necessary can efficiently solve the above problems, and have completed the present invention. .

That is, the present invention comprises: A) 97 to 75 parts by weight of rubber-modified vinyl aromatic resin; B)
3 to 25 parts by weight of polyphenylene ether, total 100
C) 1 to 15 parts by weight of red phosphorus D) 0 to 10 parts by weight of mineral oil per part by weight, wherein the weight average molecular weight of the matrix portion of the rubber-modified vinyl aromatic resin is
The object of the present invention is to provide a flame-retardant resin composition with excellent moldability, characterized in that the size is in the range of 8 x 104 to 15 x 10'. Hereinafter, the contents of the present invention will be explained in order.

The resin composition of the present invention comprises a resin component consisting of a rubber-modified vinyl aromatic resin referred to as the A component and a polyphenylene ether referred to as the B component, red phosphorus as a flame retardant imparting component, and optionally added. It is composed of mineral oil as a fluidity imparting component, and the proportion of component B in the resin component is in the range of 3 to 25% by weight. If the proportion of component B is less than 3% by weight, the flame retardance is insufficient.
If it exceeds 25% by weight, the molding processability will be extremely poor, and the more preferred range of component B, which does not fall within the scope of the present invention, is 5 to 1.5% by weight.

The rubber-modified vinyl aromatic resin of component A refers to a polymer in which a rubber-like polymer is dispersed in the form of particles in a matrix made of a vinyl aromatic polymer. Aromatic monomer (and liquid with inert solvent added)
It can be obtained by dissolving the rubber-like polymer in water and performing bulk polymerization, bulk suspension polymerization, or solution polymerization with stirring to precipitate and form a rubber-like polymer into particles.

In addition to styrene, the vinyl aromatic monomers mentioned above include styrene,
0-methylstyrene, p-methylstyrene, m-methylstyrene, 2.4 dimethylstyrene, ethylstyrene,
Nuclear alkyl-substituted styrenes such as p-tert-butylstyrene, a-alkyl-substituted styrenes such as a-methylstyrene, and α-methyl-p-methylstyrene can be mentioned, with styrene being a typical example. Two or more of these may be used in combination.

Examples of the rubbery polymer include polybutadiene, styrene/butadiene copolymer, polyisoprene, butadiene/isoprene copolymer, natural rubber, ethylene/propylene copolymer, etc. ,
Polybutadiene and styrene-butadiene copolymers are preferred.

Conventionally, the weight average molecular weight of polystyrene, which is representative of vinyl aromatic resins, has generally been adjusted to a range of 15×10 4 or more from the viewpoint of strength.

For example, Encyclopedia Polymer Science and Engineering
dia of PoIyver 5science an
d Engineering Volume 16 (1989)
As shown in Figure 1 on page 69, it was pointed out that when the weight average molecular weight of polystyrene is less than 15x104, the strength of polystyrene decreases rapidly.

However, in the case of a resin composition made by blending a small amount of polyphenylene ether with a rubber-modified vinyl aromatic resin, contrary to the above findings, even when the weight average molecular weight of the polystyrene portion is far below 15 As a result, it was discovered that a resin material with a good balance of moldability and impact resistance could be obtained.

Therefore, it is important that the weight average molecular weight of the matrix portion of the rubber-modified vinyl aromatic resin constituting the resin composition of the present invention is within a specific range different from that taught by the above-mentioned literature. That is, the rubber-modified vinyl aromatic resin of the present invention has a matrix portion with a weight average molecular weight of 8×10
If the weight average molecular weight is less than 8x104, the impact strength of the final resin composition will be poor, and
If it exceeds 10', the moldability of the resin composition will be poor. A more preferable range of the weight average molecular weight of the matrix portion is IOX 10' to 15X 10'.

When preparing a rubber-modified vinyl aromatic resin, a general method to satisfy the above requirements regarding the weight average molecular weight of the matrix portion is to adjust the polymerization temperature during bulk polymerization, bulk suspension polymerization, or solution polymerization. make it higher or
Examples include a method of adding a commonly used chain transfer agent if necessary.

There are no particular restrictions on the rubbery polymer content in the rubber-modified vinyl aromatic resin, but it is generally 4 to 15% by weight, more preferably 6 to 10% by weight.

Furthermore, the average particle diameter of the rubber particles in the rubber-modified vinyl aromatic resin is 05 to 6. It is controlled within the range of 0.0 mils, more preferably within the range of 0.8 to 3.0 mils.

The above rubber particle size was determined by taking a transmission electron micrograph (mH) of a rubber-modified vinyl aromatic resin using an ultra-thin section method.
The diameter of each rubber particle is determined according to the following formula.

Σ　n　　,D　+ Rubber particle diameter = Σ　n　　　D　＋ However, D is the diameter of the bidispersed rubber particles.

n,: Number of rubber particles with diameter Di.

Further, the gel-containing R (toluene insoluble content) in the rubber-modified vinyl aromatic resin is adjusted to 15 to 40% by weight by a conventional method, and more preferably 20 to 35% by weight.

Next, polyphenylene ether (hereinafter abbreviated as PPE) referred to as component B of the present invention is a bonding unit represented by the following formula: (Here, R, , R, , R, , R4 are each hydrogen ,
are selected from the group consisting of hydrocarbons or substituted hydrocarbon groups, and may be the same or different from each other,
), and the reduced viscosity (0.5 g/dl, chloroform solution, measured at 30°C) is tl, 15 to 0.70 dl.
/g range, more preferably 0.20-0.60dl/
homopolymers and/or copolymers within the range of g. A specific example of this PPE is poly(2,6-dimethyl-1,4-phenylene ether).

Copolymers of 2.6-dimethylphenol and 2.3.6-trimethylphenol are preferred, and among them,
(2,6-dimethyl-1,4-)ecoshin ether)
is preferred.

The method for producing such PPE is not particularly limited as long as it can be obtained by a known method. For example, a complex of a cuprous salt and an amine may be produced by the method described in U.S. Pat. It can be easily produced by oxidative polymerization of 1, for example, 2.6 xylenol, which is used as a catalyst.
specification, U.S. Patent No. 3,257.357, U.S. Patent No. 3,257,358, and Japanese Patent Publication No. 52
It can be easily produced by the method described in Japanese Patent Application Laid-Open No. 50-51197.

Next, in the present invention, red phosphorus is used as the third component. The red phosphorus may be in the form of fine particles, but from the viewpoint of handling, it is preferable to use one whose surface is coated with resin, mineral oil, or metal hydrate.

The blending amount of Joki red phosphorus needs to be 1 to 15 parts by weight based on 100 parts by weight of the resin component consisting of components A and B. If the amount is less than 1 part by weight, sufficient flame retardancy cannot be obtained, and if the amount is less than 1 part by weight,
If the amount exceeds 1 part by weight, the impact strength, moldability, and appearance of the final composition will be poor. A more preferred amount is 2 to 10 parts by weight, and an even more preferred amount is 3 to 8 parts by weight.

In the present invention, the above Al, B1. If necessary, D) mineral oil can be added to component C1 in an amount of up to 10 parts by weight based on a total of 100 parts by weight of both components A) and Bl. If the amount of mineral oil added exceeds 10 parts by weight, the heat distortion temperature of the final resin composition will decrease, and oily substances will accumulate on the mold surface during molding, which is undesirable. A more preferable amount of oil added is 3 to 6 parts by weight. As mineral oil, you can use any commonly used mineral oil, but 101! l
It is more preferable to have an initial boiling point of 210° C. or higher in mHg. Examples of mineral oils that meet these conditions include Krystle 352, a mineral oil manufactured by Esso Oil ■. Further, when polymerizing the rubber-modified vinyl aromatic resin of the component B, the entire amount or a part of the mineral oil is added to the polymerization solution to prepare a mineral oil-containing rubber-modified vinyl aromatic resin, It is also possible to adjust the amount of mineral oil contained in the finally obtained resin composition.

There is no particular restriction on the method of blending each component of the above A-C (or A-C and D), and the above components may be melt-mixed using a commonly used mixer such as an extruder, kneader, or Banbury mixer. In this case, if possible, it is better to knead the A component and B component in advance before mixing the C component, and then add the C component and mash the mixture to ensure that the B component is evenly dispersed. preferable.

EXAMPLE C The present invention will be explained in more detail with reference to the following examples] In the following examples and comparative examples, the following samples were used.

[Reference Example: Preparation of Rubber Modified Vinyl Aromatic Resin] (Reference Example 1 - Rubber Modified Vinyl Aromatic Resin, SL) A polymerization stock solution having the following composition was prepared.

Polybutadiene rubber = 8.0 parts by weight (NF35A manufactured by Asahi Kasei Corporation) - Styrene 7.0 parts by weight - Ethylbenzene: 15.0 parts by weight - a-methylstyrene timer - 0.16 parts by weight - Steryl 3 -(3,5-ditertiarybutyl-4-hydroxyphenyl) propiox-to: 0.1
0 parts by weight of the polymerization stock solution was then continuously fed into a multi-stage reactor equipped with a stirring bar to carry out polymerization. The average particle size of the rubber particles is:? , 6 microns, and the polymerization temperature and stirring number were adjusted so that the solid content concentration in the final reaction was 80% by weight. Subsequently, the polymerization liquid was led to a devolatilization device, and the rubber content was reduced to 10
% by weight of rubber-modified vinyl aromatic resin was obtained. The weight average molecular weight of the matrix portion of the obtained rubber-modified vinyl aromatic resin was 13.6×10′.

[Reference Example 2 - Rubber Modified Vinyl Aromatic Resin, S2.1 Reference Example ■, α-methylstyrene tie? -The average particle size of the rubber particles was 2.5 microns, the rubber content was 1.
0% by weight, and the weight average molecular weight of the matrix portion is 10.
A 4×10′ rubber modified vinyl aromatic resin was obtained.

[Reference Example 3 - Rubber-modified vinyl aromatic resin, S3] Rubber particles were prepared in the same manner as in Reference Example 1, except that the amount of α-methyl or tyrene 7- added was reduced, and the stirring speed of the reactor was lowered. Average particle size is 2.8 microns, rubber content 1
0% by weight, and the weight average molecular weight of the matrix portion is 20.
An 8x 10' rubber modified vinyl aromatic resin was obtained.

[gExample 4-Rubber-modified vinyl aromatic resin, 7S4] In the same manner as in Reference Example 2, except that the amount of a-J styrene tie 7- added was further increased, and the stirring number of the reactor was further increased, A rubber-modified vinyl aromatic resin was obtained in which the average particle diameter of the rubber particles was 2.8 microns, the rubber content was 10% by weight, and the weight average molecular weight of the matrix portion was 6.8 x 10'.

[Reference Example 5 Adjustment of PPE] After sufficiently purging the inside of a stainless steel reactor with an oxygen inlet at the bottom of the reactor, a cooling coil, and a stirring tube inside the reactor, cupric bromide was added. 54.8g, G-n
-butylamine 1110g, and toluene 20J2.
8.75 kg of 2.6-xylenol was dissolved in a mixed solvent of n-butanol at 16°C and methanol 4I2 and charged into the reactor. Oxygen was continuously blown into the reactor while stirring to bring the internal temperature to 30°C. Polymerization was carried out for 180 minutes under controlled conditions.After the polymerization was completed, a methanol/hydrochloric acid mixture was added to remove the precipitated polymer to decompose the remaining catalyst in the polymer, and the polymer was thoroughly washed with methanol and then dried. death,
Powdered PPE was obtained. The reduced viscosity was 0.55 dl/g.

[Examples 1 to 5, Comparative Examples 1 to 6] Rubber-modified vinyl aromatic resin PPE prepared in Reference Example and red phosphorus (manufactured by Rin Kagaku Kogyo ■, Norbalet #120.
red phosphorus content 85% by weight) and mineral oil (mineral oil manufactured by Esso Oil ■, Crystoll 352° 10m)
(initial boiling point 237° C. at mHg) were blended in the proportions shown in Table 1 and kneaded in a twin-screw extruder to obtain pellets of the resin composition.

Next, test pieces were prepared using an injection molding machine, and mechanical properties and flammability tests were conducted. The physical properties and flammability tests were conducted according to the following methods.

- Izot impact strength: ASTM D-256 (notched) - Flexural modulus: ASTM D-790 - Melt flow rate: 15O-R1133 200°C.

5kg load) Flammability: UL-94fl, /1.2 inch) The results are shown in Table 1.

(The following is a blank space) [Example 6] Using the resin composition of Example 2, an injection molding machine (I 5800B-75 manufactured by Toshiba Machine Co., Ltd.) was used at a cylinder temperature of 23.
Average wall thickness 3IIIJI under conditions of 0℃ and mold temperature 45℃
A molded body of a TV receiver outer shell part was obtained [Comparative Example 7]
] The same operation as in Example 6 was performed except that the resin composition of Comparative Example 1 was used instead of the resin composition of Example 2, but the fluidity of the resin was poor and a molded article could not be obtained. There wasn't.

[Example 7] The same operation as in Example 6 was performed except that the resin composition of Example 5 was used instead of the resin composition of Example 2, and the cylinder temperature was 220°C. A molded body of a shell part was obtained.

(The following is a blank space) [Effects of the Invention] As is clear from Table 1, the resin composition of the present invention has excellent impact strength, flame retardance, and fluidity, and is useful as a material for injection molding. Furthermore, the resin composition of the present invention has particularly excellent fluidity and is therefore suitable for obtaining large molded products such as outer shell parts of television receivers.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Scope of Claims] 1) A) 97 to 75 parts by weight of a rubber-modified vinyl aromatic resin, B) 3 to 25 parts by weight of polyphenylene ether, a total of 1
00 parts by weight, C) 1 to 15 parts by weight of red phosphorus D) 0 to 10 parts by weight of mineral oil, wherein the weight average molecular weight of the matrix portion of the rubber-modified vinyl aromatic resin is
A flame-retardant resin composition characterized in that the molecular weight is in the range of 8 x 10^4 to 15 x 10^4.