JPH06263940A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent lightshielding property and environmental conformability and useful as a food packaging material, an optical display part, etc., by compounding a styrenic resin with titanium oxide, carbon black and a mineral filler at specific ratios. CONSTITUTION:This resin composition is produced by compounding (A) 100 pts.wt. of a styrenic resin with (B) 0.1-20 pts.wt. of titanium oxide, (C) 0.5-10wt.% (based on the titanium oxide) of carbon black and (D) 5-60 pts.wt. of a mineral filter such as aluminum oxide or aluminum silicate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrenic resin composition having an excellent light-shielding property.

[0002]

2. Description of the Related Art Among beverages such as milk drinks and lactic acid drinks,
Many of them deteriorate when exposed to light for a long time. Therefore,
It is desirable to enclose them in a light-shielding container from the time of manufacture to the time of consumption in order to prevent deterioration and guarantee quality. However, the light-shielding property of the conventionally used mixture of titanium oxide is not always satisfactory.

For this reason, a method of blending a relatively large amount of titanium oxide has been proposed, but it is not practically preferable due to deterioration of mechanical properties of a molded product and economic problems. Further, when discarded, the styrene resin composition is a cause of significantly shortening the life of the incinerator because of its high calorific value of combustion heat.

[0004]

DISCLOSURE OF THE INVENTION The present invention contains titanium oxide and a mineral filler in a styrene resin in order to provide a styrene resin composition having excellent light-shielding properties, environmental friendliness, and texture of molded products. And also contains carbon black.

[0005]

That is, according to the present invention, 0.1 to 20 parts by weight of titanium oxide and 0.5 to 10 wt% of titanium oxide are used with respect to 100 parts by weight of styrene resin.
Another object of the present invention is to provide a thermoplastic resin composition obtained by uniformly blending the carbon black of No. 1, and 5 to 60 parts by weight of a mineral filler.

The present invention will be described in detail below.

In the present invention, the basic styrene resin is a styrene homopolymer or styrene-based styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene- Examples thereof include acrylonitrile-butadiene copolymer and impact-resistant polystyrene.

The titanium oxide used in the present invention is commercially available as a normal white pigment or light shielding agent, and may be either anatase or rutile type. Further, even a mixture thereof may be used. The particle size is not particularly limited, but is generally 0.1 to 5 μm, and particularly preferably 0.1 to 3.0 μm.
Further, the addition amount of titanium oxide is 0.1 to 20 parts by weight with respect to 100 parts by weight of the styrene resin, and if it is more than 100 parts by weight, poor dispersion occurs, which is not preferable. 0.
When it is less than 1, the light-shielding property is not sufficient, which is not preferable.

Examples of the carbon black used in the present invention include furnace black and channel black. Carbon black generally has a particle size of 0.
Since it is as small as 01 to 0.5 μm, it is very difficult to directly mix it in the basic styrene resin composition. Therefore, it is preferable to preliminarily mix the carbon black and the plasticizer in the form of a paste sufficiently kneaded with a paint mill. The decrease in dispersibility not only causes color unevenness in appearance, but also causes a large decrease in physical properties.
The amount of carbon black added is 0.5 with respect to titanium oxide.
10 to 10 wt%, preferably 0.5 to 1 wt%. 1
When it exceeds 0 wt%, mechanical properties such as impact strength are deteriorated, which is not preferable. If it is less than 0.5 wt%, the light-shielding property is not sufficient, which is not preferable.

The mineral filler used in the present invention may be any one commonly used in synthetic resins and rubbers, for example, aluminum oxide, aluminum silicate, antimony oxide, colloidal silica, barium titanate, calcium carbonate, barium sulfate. , Calcium sulfate, silica, shirasu balloon, fluorite, diatomaceous earth, and talc. Of these, talc is preferred from the viewpoint of price and environmental friendliness. The particle size is preferably about 1 to 100 μm, and the particles may be subjected to a coupling treatment. Further, if the workability is poor at the time of kneading this product by dry blending, master batch pellets may be used. The addition amount is 5 to 60 parts by weight based on 100 parts by weight of the styrene resin.
If the amount is less than 5 parts by weight, there is no calorie reduction effect when burning,
If it exceeds 0 part by weight, mechanical properties such as impact strength are deteriorated, which is not preferable.

In the production of the composition of the present invention, a styrene resin and the titanium oxide, carbon black and mineral filler are added, if necessary, as a dispersant, a lubricant, an antistatic agent, an antiblocking agent, an antioxidant, It is made by further adding an organic ultraviolet stabilizer and the like and heating and kneading with a single-screw or twin-screw extruder, a Banbury mixer, a kneader, a mixing roll and the like. At this time, titanium oxide may be used as a masterbatch in which a resin is mixed in a high concentration in advance. Further, it is preferable to use a dispersant for titanium oxide, for example, an organic acid and a metal salt thereof, and a coupling agent such as a silane-based, titanate-based, and aluminum-based, and among these dispersants, lauric acid, Metal salts of organic acids having 10 to 26 carbon atoms such as stearic acid and 10 to 26 carbon atoms such as zinc stearate, and isopropyl triisostearoyl titanate, bis (dioctel pyrophosphate) oxyacetate titanate, etc. A titanate coupling agent is particularly preferred. Further, these dispersants may be added during the production of the composition,
Further, titanium oxide may be used after being surface-treated with these dispersants before the production of the composition.

Examples of the method for molding the styrene resin composition include an extrusion molding method, an injection molding method and a press molding method. Further, a molding method that is generally used in the field of thermoplastic resins such as a stamping method, a press molding method using an extruded sheet, and a molding method such as a vacuum molding method may be applied.

[0013]

EXAMPLES The present invention will be described in detail with reference to examples.

Examples 1 to 11, Comparative Examples 1 to 7 Styrenic resin (high impact polystyrene: E58
0 Sumitomo Chemical Co., Ltd.), titanium oxide (JR405 Teika Co., Ltd., average particle size 0.21 μm, rutile type), mineral filler, and carbon black in the compounding amounts shown in Table 1 (all (Parts by weight) was preliminarily dry blended for 2 minutes in a Henschel mixer. Each of the resulting mixtures was twin-screw extruder (screw diameter 35 mm)
According to the above, pellets were produced while kneading at a resin temperature of 210 ° C. Further, each of the obtained pellets was molded into a sheet having a thickness of 0.6 mm by a sheet molding machine under the same conditions as described above to prepare a transmitted light measurement sample, and the light transmittance was measured.

The results are shown in Table 1.

[0016]

[Table 1]

[0017]

From the results of the above Examples and Comparative Examples,
It is clear that the sheet made of the composition obtained according to the present invention has a very good light-shielding property. Therefore, when applied to thin molded products, it has excellent light-shielding properties, so it is promising as a component for optical display parts of household electrical appliances and automobile products, and also as a packaging material for food and photosensitive materials. Is.

Claims (1)

[Claims] 1. To 100 parts by weight of styrene resin,
0.1 to 20 parts by weight of titanium oxide and 0.5 to 10 wt% of carbon black based on titanium oxide, and further 5
A thermoplastic resin composition obtained by uniformly mixing 60 parts by weight of a mineral filler.