JP3471981B2 - Styrene polymer composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene polymer having excellent moldability, transparency, impact resistance and chemical resistance. [0002] Styrene-based polymers are widely used as molding materials for electric appliances, various containers, toys, miscellaneous goods and the like because of their excellent moldability, transparency and low price. Recently, it has been studied as a substitute for an expensive AS resin, and a high-performance and inexpensive styrene-based polymer has been desired.
It is known that the impact resistance, which is particularly important among the styrene-based polymer performances, can be improved by increasing the molecular weight.However, when the molecular weight is increased, the moldability becomes poor, and in order to improve the moldability, liquid paraffin is used. It has been difficult to simultaneously improve multipurpose qualities such as the addition of a lubricant such as the above, in which rigidity and heat resistance are reduced. As a method for simultaneously improving multi-purpose quality, the molecular weight of a styrenic polymer is disclosed in Japanese Patent Publication Nos. 62-61231, 2-170806 and 3-33142. And methods for adjusting the molecular weight distribution and balancing the moldability and impact resistance have been proposed, but these methods have not yet satisfied the demand for improvement as an alternative to AS resins. The inventors of the present invention have conducted various studies to solve the above-mentioned problems. As a result, since the styrene polymer has a specific molecular weight and a molecular weight distribution, and the styrene polymer has a specific solution viscosity, moldability, The present invention has been achieved by simultaneously improving not only transparency and impact resistance but also chemical resistance. [0005] That is, the present invention relates to a method for producing a polymer having a weight average molecular weight (Mw) of 380,000 or more, a molecular weight of 2,000,000 or more and less than 0.8% by weight, and a molecular weight of 50,000 or less less than 8% by weight. A styrene polymer having a viscosity of 30 cp to 60 cp at 25 ° C. in a 10% by weight solution of toluene .
It relates to a tylene polymer . Hereinafter, the present invention will be described in detail. Of the present invention
The styrene polymer is obtained by polymerizing a styrene monomer . As a method for polymerizing the styrene monomer, a known method such as a suspension polymerization method, a bulk polymerization method, a solution polymerization method, and an emulsion polymerization method can be used, and either continuous polymerization or batch polymerization may be used.
The molecular weight of the styrene polymer is 3 in weight average molecular weight (Mw).
It is 80,000 or more, preferably 400,000 to 600,000. Mw is 3
If it is less than 80,000, impact resistance and chemical resistance are poor. The styrene polymers of the present invention has a molecular weight of less than 2,000,000 more styrene polymer 0.8% by weight, preferably 0.2 to 0.7 wt%, a molecular weight of 50,000 or less in styrene heavy
It has a molecular weight distribution containing less than 8% by weight, preferably 2 to 7% by weight, of the union . Styrene with a molecular weight of 2,000,000 or more
When the combined content is 0.8% by weight or more, the impact resistance is good, but the moldability, transparency and chemical resistance are inferior, and even when the styrene polymer having a molecular weight of 2,000,000 or more is less than 0.8% by weight. 8% by weight of a styrene polymer having a molecular weight of 50,000 or less
When the above is included, the moldability is good but the impact resistance and the chemical resistance are inferior. The molecular weight and molecular weight distribution can be adjusted by adjusting the polymerization initiator, the chain transfer agent, and the polymerization temperature. There is also a method of adding a crosslinking agent such as divinylbenzene as a method for obtaining a polymer having a high molecular weight. However, this method is not preferable because a styrene polymer having a molecular weight of 2,000,000 or more increases. As the polymerization initiator, known monofunctional initiators and polyfunctional initiators can be used. From the viewpoint of molecular weight and molecular weight distribution, a bifunctional initiator is used, and
The polymerization is preferably carried out at a temperature of 15 ° C. or higher and a conversion rate of 50% or higher at a temperature lower than the half-life time of the time, and the amount of the polymerization initiator added should not exceed 0.3 part by weight based on 100 parts by weight of the styrene monomer. Is preferred. The molecular weight and molecular weight distribution of the present invention are GP
The measurement was performed under the following conditions by the C measurement method, and the content was calculated by the area ratio. Measuring machine: Tosoh HLC-802A Column: Tosoh TSK-GEL 6000H6-
5000H6 (however , the molecular weight of a styrene polymer having a molecular weight of 50,000 or less uses TSK-GEL GMH6 × 2). The styrene polymer of the present invention is 10% of toluene.
The viscosity of the weight% solution at 30C is 30 cp to 60 cp, preferably 35 to 55 cp. If it is less than 30 cp, impact resistance and chemical resistance are poor, and if it exceeds 60 cp, moldability is poor. The viscosity of a 10% by weight solution of a styrene polymer in toluene can be adjusted by additives such as a polymerization initiator, a chain transfer agent, a polymerization temperature, and liquid paraffin during polymerization of the styrene polymer . The viscosity of the 10% by weight solution of the styrene polymer of the present invention in toluene was measured using a single cylinder rotational viscometer (TOKI).
(Manufactured by MEC). [0010] The styrene polymer of the present invention comprises a lubricant or a plasticizer such as stearic acid, zinc stearate, ethylene bisstearyl amide, or liquid paraffin;
-Butyl-4-methylphenol, octadecyl-3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate, trimethylene glycol-bis [3-
(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 2- (2-hydroxy-5-methyl-phenyl) -2H-benzotriazole, bis (2,2,6 A known additive such as a weathering agent such as (6,6-tetramethyl-4-piperidyl) sebacate and an antistatic agent such as polyethylene glycol can also be added. As a method for mixing these additives and the like, dry blending may be carried out using a kneading roll, Banbury mixer, Henschel mixer, ribbon blender, super mixer, V blender, or the like. You may. Among them, single screw extruder and 2
A method of performing melt kneading using a screw extruder is preferable because kneading and pelletization can be easily performed. EXAMPLES The present invention will be further described with reference to examples, but the present invention is not limited to these examples. In addition, the physical property test method of an Example is described below. Moldability: Injection molding under the following conditions, flow length (L)
Was measured, and a number (L / T) obtained by dividing L by a molded product thickness of 2 mm (T) was used as a guide for moldability. Molding machine: Toshiba Machine Co., Ltd. IS30EPN Mold: Spiral mold of 8 mm width and 2 mm thickness Injection temperature: 240 ° C Mold temperature: 40 ° C Injection pressure: 50 kg / cm ² G Transparency: Molding under the following conditions Product thickness 2mm
The haze of each part was measured based on JIS K7105 and used as a guideline for transparency. Molding machine: SN-51B manufactured by Niigata Iron and Steel Works Mold: Three-stage plate mold having a thickness of 1 mm, 2 mm, and 3 mm Injection temperature: 230 ° C Mold temperature: 40 ° C Impact resistance: Molded article molded under the following conditions 3m thick
For the m part, the 50% breaking height of a 50 g weight was measured based on JIS K7211 and used as a guide for impact resistance. Molding machine: SN-51B manufactured by Niigata Iron and Steel Works Mold: Three-stage plate mold of 1 mm, 2 mm, 3 mm Injection temperature: 230 ° C Mold temperature: 40 ° C Chemical resistance: Thickness by compression molding method (200 ° C) A 1 mm-shaped test piece was measured for critical strain by a quarter ellipse method using mama lemon (manufactured by Lion Corporation) as a chemical, and used as a guideline for chemical resistance. Example 1 In an autoclave having a capacity of 15 L, 5 kg of pure water, 0.15 g of sodium dodecylbenzenesulfonate and 20 g of tribasic calcium phosphate were added and stirred at 300 rpm. Subsequently, 5 kg of styrene, 5 g of stearic acid, 5 g of t-butyl peroxyacetate (1 hour half-life temperature 12
3 ° C.) was dissolved and mixed in advance and charged into an autoclave. The autoclave is sealed and kept at 100 ° C. for 10 hours.
Polymerization was performed at 135 ° C. for 3 hours. Next, hydrochloric acid was added until the pH became 3 or less, dehydration was performed by centrifugal filtration, drying was performed at 70 ° C. for 4 hours, and a 40 mmφ single screw extruder (I.
The mixture was extruded at 230 ° C. using KG to obtain a pellet-shaped styrene polymer composition. Table 1 shows the results of measuring various physical properties. Example 2 Instead of 5 g of t-butyl peroxyacetate,
The procedure was performed in the same manner as in Example 1 except that 5 g of 2-di- (t-butylperoxy) butane was used (1 hour half-life temperature: 121 ° C.). Table 1 shows the results of measuring various physical properties. Example 3 Instead of 5 g of t-butylperoxyacetate, 5 g of tris- (t-butylperoxy) triazine (1 hour half-life temperature: 130 ° C.) was used, and heated at 116 ° C. for 10 hours.
The procedure was performed in the same manner as in Example 1 except that polymerization was performed at 135 ° C. for 3 hours. Table 1 shows the results of measuring various physical properties. Example 4 The procedure of Example 1 was repeated, except that 10 g of 5 g of t-butyl peroxyacetate was used. Table 1 shows the results of measuring various physical properties. Comparative Example 1 The procedure of Example 1 was repeated except that 1 g of t-dodecylmercaptan was mixed with styrene and then charged. Table 2 shows the results of measuring various physical properties. It turns out that it is inferior to impact resistance and chemical resistance. Comparative Example 2 The procedure of Example 1 was repeated, except that 5 g of tris- (t-butylperoxy) triazine (1 hour half-life temperature 130 ° C.) was used instead of 5 g of t-butyl peroxyacetate. Table 2 shows the results of measuring various physical properties. It can be seen that the moldability, transparency, and chemical resistance are poor. Comparative Example 3 In an autoclave having a capacity of 15 L, 5 kg of pure water, 0.15 g of sodium dodecylbenzenesulfonate and 20 g of tribasic calcium phosphate were added, followed by stirring at 300 rpm. Subsequently, 5 kg of styrene, 5 g of stearic acid, 5 g of t-butyl peroxyacetate, and 50 g of t-dodecyl mercaptan were mixed in advance and charged into the autoclave. The autoclave is sealed and kept at 100 ° C. for 10 hours.
Polymerization was performed at 135 ° C. for 3 hours. Next, neutralization, dehydration, and drying were performed, and extrusion was performed to obtain a pellet. The resin (referred to as A) and the resin (referred to as B) obtained in Example 2 were mixed at a ratio of A / B = 90/10 (% by weight) and extruded to form a pellet. Table 2 shows the results of measuring various physical properties. It turns out that it is inferior to impact resistance and chemical resistance. Comparative Example 4 Resin A in Comparative Example 3 and resin (C) obtained in Example 1
) Were mixed at a ratio of A / C = 95/5 (% by weight) and extruded to obtain a pellet shape. Table 2 shows the results of measuring various physical properties. It turns out that it is inferior to impact resistance and chemical resistance. Comparative Example 5 The procedure of Example 1 was repeated except that 5 g of t-butyl peroxyacetate was used instead of 16 g. Table 3 shows the results of measuring various physical properties. It turns out that it is inferior to impact resistance and chemical resistance. Comparative Example 6 5 g of 2,2-di- (t-butylperoxy) butane was added to 1 g of
The procedure was performed in the same manner as in Example 2 except that the amount was 6 g. Table 3 shows the results of measuring various physical properties. It turns out that it is inferior to impact resistance and chemical resistance. Comparative Example 7 The procedure of Example 2 was repeated except that the polymerization was carried out at 95 ° C. for 10 hours and at 135 ° C. for 3 hours. Table 3 shows the results of measuring various physical properties. It can be seen that the moldability, transparency and chemical resistance are poor. In the examples, the conversion (%) after 10 hours was sampled from the reaction solution after 10 hours, and the conversion of the styrene monomer was quantified by gas chromatography. [Table 1] [Table 2] [Table 3] The styrenic polymer composition of the present invention has an excellent balance of moldability, transparency, impact resistance and chemical resistance.
Useful for AS resin replacement.

   ────────────────────────────────────────────────── ─── Continuation of front page       (56) References JP-A-7-268152 (JP, A)                 JP-A-7-166013 (JP, A)                 JP-A-6-256420 (JP, A)                 JP-A-5-222125 (JP, A)                 JP-A-7-252309 (JP, A)                 JP-A-60-168710 (JP, A)                 JP-A-57-164106 (JP, A)                 JP-A-57-165414 (JP, A)                 JP-A-58-91748 (JP, A)

Claims (1)

(57) Claims 1. A styrene polymer having a weight average molecular weight (Mw) of 380,000 or more, a molecular weight of 2,000,000 or more, less than 0.8% by weight, and a molecular weight of 50,000 or less, less than 8% by weight. And a 10% by weight solution of toluene having a viscosity of 30 cp at 25 ° C.
Styrene polymer of 60 cp.