JP2003128857A - Styrenic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrenic resin composition which excels in moldability and maintains surface hardness, impact resistance and transparency. SOLUTION: The composition contains a styrenic resin having a Shore hardness A value of 98 or more and a vinyl polymer having a weight average mol.wt. of 1,000-30,000 and hydroxyl groups. The vinyl polymer having hydroxyl groups is obtained by either polymerizing a monomer having a hydroxyl group or polymerizing a vinyl monomer in the presence of a chain transfer agent having a hydroxyl group. Those representative of the styrenic resin having a Shore hardness A value of 98 or more include polystyrene resins, acrylonitrile- butadiene-styrene resins and the like.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a high surface hardness,
The present invention relates to a styrene resin composition having excellent impact resistance.

[0002]

2. Description of the Related Art Polystyrene resin and acrylonitrile
Styrene resins such as butadiene-styrene resin (hereinafter referred to as ABS resin) have excellent mechanical properties such as surface hardness and impact resistance, and are used for housings of electronic devices and various packages. The sex may not be sufficient. For example, polystyrene resin, thermoplastic polyurethane,
A resin composition comprising a vinyl polymer having a functional group and a polyfunctional isocyanate is known (JP-A-9-7793).
No. 6), however, such a composition may have poor moldability depending on conditions, and its use is limited. As a method of improving the moldability of a styrene resin, a technique of adding a styrene-acrylic acid ester copolymer is known (JP-A No. 11-92528), but the moldability and the transparency are sufficient depending on the conditions. Not always.

[0003]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a styrene resin composition which is excellent in moldability and maintains surface hardness, impact resistance and transparency.

[0004]

In order to solve the above-mentioned problems, the styrene resin composition of the invention according to claim 1 is
It is characterized by containing a styrene-based resin having a Shore hardness of A98 or more and a vinyl polymer having a weight average molecular weight of 1,000 to 30,000 and a hydroxyl group. The styrene resin composition of the invention according to claim 2 is
The invention according to claim 1 is characterized in that the vinyl polymer is obtained by copolymerizing a vinyl monomer having a hydroxyl group and a vinyl monomer having no hydroxyl group. A styrene-based resin composition according to a third aspect of the present invention is the styrene-based resin composition according to the second aspect, wherein the vinyl monomer having no hydroxyl group has styrene and a hydroxyl-free (meth) acrylic monomer. It is characterized by being selected from the group consisting of the body. The styrene resin composition of the invention described in claim 4 is obtained by polymerizing a vinyl monomer in the presence of a chain transfer agent having a hydroxyl group in the invention described in claim 1. It is characterized by. A styrene-based resin composition according to a fifth aspect of the present invention is the styrene resin composition according to any one of the first to fourth aspects, wherein the vinyl polymer contains a vinyl monomer at 180 to 350 ° C.
It is obtained by polymerizing at the temperature of. The styrene resin composition of the invention according to claim 6 is
The invention according to any one of claims 1 to 5 is characterized in that the proportion of the vinyl polymer is 0.1 to 30 parts by mass based on 100 parts by mass of the styrene resin. The styrene resin composition of the invention described in claim 7 is characterized in that, in the invention described in any one of claims 1 to 6, the styrene resin is a polystyrene resin. The styrene-based resin composition of the invention described in claim 8 is the invention according to any one of claims 1 to 6, wherein the styrene-based resin is acrylonitrile-butadiene-
It is characterized by being a styrene resin.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. In the present specification, acryl and methacryl are collectively referred to as (meth) acryl.

The styrenic resin is a base component of the composition of the present invention. The styrene resin used in the present invention is a polymer having a styrene unit as a main constituent unit and having a Shore hardness A of 98 or more. Examples thereof include polystyrene resins, ABS resins, and AXS resins in which butadiene, which is a rubber component of the ABS resin, is replaced with a rubber component other than butadiene, and those having a Shore hardness A of 98 or more. Specific examples of the AXS resin include ASA resin in which butadiene is replaced by acrylic rubber, ACS resin in which chlorinated polyethylene is replaced, AES resin in which ethylene-propylene rubber is replaced, ethylene-vinyl acetate copolymer is replaced, and olefin. The OSA resin replaced by High impact polystyrene resin with a large amount of rubber (hereinafter referred to as HIPS
Say. ) Is also included in the styrene resin.

Generally, what is called an elastomer has a Shore hardness A of 90 or less and cannot be used in the present invention. Shore hardness is JIS K7215 (Durometer
A hardness) is measured. The styrene resin composition obtained by using a styrene resin having a Shore hardness of A98 or more has a large surface hardness. A styrene resin having a Shore hardness A of 100 or more is more preferable for the present invention. A styrene resin having a Shore hardness of less than A98 is not preferable because the obtained styrene resin has a small surface hardness. Among the styrene resins, polystyrene resin and ABS resin are particularly preferable because the resulting styrene resin composition has an excellent balance of moldability, surface hardness, transparency and the like.

The styrene resin composition of the present invention contains a vinyl polymer having a weight average molecular weight of 1,000 to 30,000 and having a hydroxyl group (hereinafter, also referred to as a hydroxyl group-containing low molecular weight vinyl polymer). The vinyl polymer is an important component for making the styrene resin composition excellent in moldability without impairing impact resistance and transparency. The hydroxyl group-containing low molecular weight vinyl polymer has a weight average molecular weight of 1
000-30000, preferably 1000-20
It is 000. When the weight average molecular weight is less than 1000, the resulting composition has low strength, which is not preferable. When it is more than 30,000, the resulting composition has poor moldability, which is not preferable.

The hydroxyl group contained in the hydroxyl group-containing low molecular weight vinyl polymer is an important factor for maintaining the transparency of the composition. It is presumed that the transparency is maintained because the compatibility with the styrene resin is likely to be good. The hydroxyl group-containing low molecular weight vinyl polymer is a method of copolymerizing a vinyl monomer having a hydroxyl group and a vinyl monomer having no hydroxyl group, and polymerizing the vinyl monomer in the presence of a chain transfer agent having a hydroxyl group. It can be obtained by a known method such as a method.

As the vinyl monomer having a hydroxyl group,
Having a hydroxyl group such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate (meth)
Acrylic monomers, allyl alcohol and the like can be mentioned, and (meth) acrylic monomers having a hydroxyl group are preferable because they have good polymerizability. Examples of the vinyl monomer having no hydroxyl group include styrene, α-methylstyrene, a hydroxyl group-free (meth) acrylic monomer, acrylonitrile, vinyl acetate and the like, which have styrene and a hydroxyl group. (Meth) acrylic monomer is preferable because it is easy to copolymerize with a vinyl monomer having a hydroxyl group. Specific examples of the (meth) acrylic monomer having no hydroxyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate,
Butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic Examples thereof include (meth) acrylic acid esters such as cyclohexyl acid, isobornyl (meth) acrylate, and benzyl (meth) acrylate, and (meth) acrylic acid. The hydroxyl group-containing low molecular weight vinyl polymer is obtained by radically polymerizing the above-mentioned monomers by a known method.

The hydroxyl group-containing low molecular weight vinyl polymer can also be obtained by a method of polymerizing a vinyl monomer in the presence of a chain transfer agent having a hydroxyl group. The vinyl monomer used in the method is not particularly limited, but those exemplified as the vinyl monomer having a hydroxyl group and the vinyl monomer having no hydroxyl group can be used.

Examples of the chain transfer agent having a hydroxyl group include isopropyl alcohol and mercaptoethanol. Isopropyl alcohol is preferable because unreacted one can be easily collected and reused. The hydroxyl group-containing low molecular weight vinyl polymer can also be obtained by radically polymerizing a vinyl monomer by a known method in the presence of a chain transfer agent having a hydroxyl group.

The polymerization method may be any of bulk polymerization, solution polymerization, emulsion polymerization and the like, but bulk polymerization or solution polymerization is preferred. Further, any method such as batch polymerization, continuous polymerization, semi-continuous polymerization in which only raw materials are continuously supplied can be adopted. The radical polymerization initiator, solvent and the like can be appropriately selected and used as necessary. The polymerization temperature is not particularly limited, but the polymerization is usually performed at room temperature to 350 ° C.

When the hydroxyl group-containing low molecular weight vinyl polymer is obtained by continuously polymerizing vinyl monomers at a temperature of 180 to 350 ° C., the resulting styrene resin composition has particularly good moldability. It is preferable because impact resistance is likely to be maintained. 180 to 35 vinyl monomer
The continuous polymerization at a temperature of 0 ° C. can be carried out by a known method (JP-A-57-502171, JP-A-59-6207, JP-A-60-215).
No. 007 publication).

The composition of the present invention contains a styrene resin and the above hydroxyl group-containing low molecular weight vinyl polymer. A composition in which the proportion of the hydroxyl group-containing vinyl polymer is 0.1 to 30 parts by mass based on 100 parts by mass of the styrene resin is particularly preferable because the moldability, impact resistance and transparency are good. A more preferable ratio is 0.5 to 20
Parts by mass. If the proportion of the hydroxyl group-containing vinyl polymer is too low, the moldability may be poor, and if it is too high, the transparency may be poor.

The composition of the present invention may be added with various additives which are usually added to molding materials. Examples of the additive include polymers other than the styrene resin and the hydroxyl group-containing low molecular weight vinyl polymer, crosslinking agents, fillers, pigments, lubricants, plasticizers and the like. The composition of the present invention can be obtained by mixing the above components by a known method. An example of the mixing method is a method in which a mixture of the components is kneaded while being heated by a hot roll or an extruder.

[0017]

EXAMPLES The above embodiments will be described more specifically with reference to Examples and Comparative Examples. In each of the following examples, “part” means “part by mass” and “%” means “% by mass”.

1. Production Example of Vinyl Polymer (Polymer 1) A 300 ml vessel equipped with a heat transfer heater in a pressure type stirred tank reactor was filled with ethyl 3-ethoxypropionate, the temperature was adjusted to 210 ° C., and the pressure was gauged by a pressure regulator. Pressure 2.45 to 2.65 MPa (25 to 27 kg / c
m ² ). Then, while keeping the pressure of the reactor constant, 80 parts of styrene (hereinafter referred to as St), 20 parts of hydroxyethyl methacrylate (hereinafter referred to as HEMA), 20 parts of methyl ethyl ketone (hereinafter referred to as MEK) as a solvent, and polymerization. A monomer mixture consisting of 1 part of ditertiarybutyl peroxide as an initiator was continuously fed from the raw material tank to the reactor at a constant feed rate (23 g / min (residence time: 13 min)). Then, a reaction product corresponding to the supply amount of the monomer mixture was continuously extracted from the outlet. Immediately after the solution was sent, the reaction temperature was once lowered and then increased by the heat of polymerization, but the reaction temperature was maintained at 210 ° C. by controlling the heater. The point at which the temperature became stable after the start of the supply of the monomer mixture was set as the starting point for collecting the reaction solution, and the reaction was continued for 154 minutes.
0 g of the monomer mixture was supplied and 1950 g of the reaction mixture was recovered. The reaction solution obtained was introduced into a thin film evaporator, 23
Volatile components such as unreacted monomers and solvents were removed under reduced pressure at 5 ° C. and 30 mmHg to obtain about 1500 g of a liquid polymer (polymer 1). As a result of gas chromatographic analysis, the amount of unreacted monomer in the liquid resin was 0.5 g or less. Tetrahydrofuran was used as a solvent, and the weight average molecular weight (hereinafter, referred to as Mw) of the polymer 1 obtained by converting the molecular weight obtained by gel permeation chromatography (hereinafter, referred to as GPC) into polystyrene was 2,470.

(Polymer 2 to 16) The composition of the monomer mixture to be used is changed as shown in Tables 1 to 4, and otherwise the same operation as in the production method of the polymer 1 described above is repeated. 16 were obtained respectively. MMA is methyl methacrylate, HEA
Means hydroxyethyl acrylate and BA means butyl acrylate.

(Polymer 17) 500 g of MEK as a solvent was charged in a 3 L flask equipped with a stirrer installed in a water bath,
The temperature was adjusted to 80 ° C. And St 800g, HEMA 20
A solution consisting of 0 g, MEK 200 g, azobisisobutyronitrile 30 g, and mercaptoethanol 70 g was used as a raw material, and continuously added to the flask at a constant rate for 4 hours. During the reaction, the temperature was maintained at 80 ° C., and after the completion of feeding the monomer solution, the temperature was maintained at 80 ° C. for 1 hour to complete the reaction. The reaction solution obtained was introduced into a thin film evaporator to obtain 235
° C. Under reduced pressure of 30 mmHg, volatile components such as unreacted monomers were removed to obtain a polymer 17.

(Polymer 18) 500 g of MEK as a solvent was charged in a 3 L flask equipped with a stirrer installed in a water bath,
The temperature was adjusted to 80 ° C. And St 800g, HEMA 20
A solution consisting of 0 g, MEK 200 g, azobisisobutyronitrile 30 g, and mercaptoethanol 20 g was used as a raw material and continuously added to the flask at a constant rate for 4 hours. During the reaction, the temperature was maintained at 80 ° C., and after the completion of feeding the monomer solution, the temperature was maintained at 80 ° C. for 1 hour to complete the reaction. The reaction solution obtained was introduced into a thin film evaporator to obtain 235
° C. Volatile components such as unreacted monomers were removed under reduced pressure of 30 mmHg to obtain a polymer 18.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

2. Composition preparation method Transparent ABS (Toyolac 900 manufactured by Toray Industries, Inc.) resin or transparent HIPS (SX1 manufactured by A & M Polystyrene Co., Ltd.) with 5 inch two test rolls at a temperature of 160-170 ° C.
00) 100 parts and 3 parts of the polymer were melted and kneaded for 10 minutes to prepare a composition. Then, a test piece was prepared by hot pressing at 190 ° C. ABS and HIPS
The surface hardness of the above and the surface hardness of the test pieces manufactured in the examples were both Shore hardness A100 or more.

3. Moldability Evaluation of Composition The melt flow index (hereinafter referred to as MFR) of the above composition was measured according to Condition 12 of JIS K7210. The larger the MFR value, the better the moldability.

4. Impact test of composition According to JIS K7110, a No. 1 A test piece was prepared and Izod impact value was measured.

5. Transparency test of composition The composition was hot-pressed at 190 ° C to prepare a 10 cm x 12 cm x 4 mm test piece, and the presence or absence of turbidity was visually confirmed. O means that there was no turbidity, and X means that there was turbidity.

6. Discussion of Evaluation Results It was found that the compositions of Comparative Examples 1 and 7 had a small MFR value and poor moldability. It is presumed that the reason is that the polymer (the vinyl polymer having a weight average molecular weight of 1,000 to 30,000 and a hydroxyl group) is not added. The compositions of Comparative Examples 2 to 5 and 8 had poor transparency. It is presumed that the reason is that the added polymer does not have a hydroxyl group. Although the polymer was added to the composition of Comparative Example 6, it was found that the MFR value was small and the moldability was poor. It is presumed that the reason is that the polymer has a large weight average molecular weight of 84,000. It was found that the compositions of Examples all had a large MFR value and good moldability as compared with the compositions to which no polymer was added. Moreover, the Izod impact strength and transparency were maintained. The composition of Example 13 was not so large in MFR, but was due to the difference in the polymerization method by which the polymer was produced (not obtained by continuously polymerizing vinyl monomers at a temperature of 180 to 350 ° C.). It is estimated to be.

[0031]

EFFECT OF THE INVENTION A styrenic resin composition having excellent moldability, surface hardness, impact resistance and transparency was obtained.

Claims (8)

[Claims] 1. A styrene resin composition containing a styrene resin having a Shore hardness of 98 or more and a vinyl polymer having a weight average molecular weight of 1,000 to 30,000 and a hydroxyl group. 2. The styrene resin composition according to claim 1, wherein the vinyl polymer is obtained by copolymerizing a vinyl monomer having a hydroxyl group and a vinyl monomer having no hydroxyl group. 3. A vinyl monomer having no hydroxyl group,
The styrene resin composition according to claim 2, which is selected from the group consisting of styrene and a (meth) acrylic monomer having no hydroxyl group. 4. The styrene resin composition according to claim 1, wherein the vinyl polymer is obtained by polymerizing a vinyl monomer in the presence of a chain transfer agent having a hydroxyl group. 5. The vinyl polymer comprises 180 vinyl monomers.
The styrene-based resin composition according to any one of claims 1 to 4, which is obtained by polymerizing at a temperature of ~ 350 ° C. 6. The styrene resin composition according to claim 1, wherein the proportion of the vinyl polymer is 0.1 to 30 parts by mass based on 100 parts by mass of the styrene resin. 7. The styrene resin composition according to claim 1, wherein the styrene resin is a polystyrene resin. 8. The styrene resin is acrylonitrile-
The styrene-based resin composition according to claim 1, which is a butadiene-styrene resin.