JPH041016B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition in which ultrafine powdered silicic acid having special powder properties is used in combination with thermoplastic plastics, and the main purpose is to improve moldability and, in the case of transparent plastics, to improve light diffusion. It is the granting of gender. Conventionally, calcium carbonate (Japanese Unexamined Patent Publication No. 57-155245) or a combination of calcium carbonate and aluminum hydroxide (Unexamined Japanese Patent Publication No. 57-155245) have been used for this purpose.
No. 162743) etc. are known facts.
However, these materials merely have light diffusing properties, but the ultrafine powder silicic acid used in the present invention not only has superior light diffusing properties, but also has superior light diffusing properties.
This invention has been completed because it has the effect of improving moldability and is also economically advantageous. The ultrafine powdered silicic acid used in the present invention is produced by spray-drying colloidal silica (Snowtex (trade name); Nissan Chemical Industries, Ltd.), but it can also be surface-treated with other plastics, etc. Of course, it is also applicable. The powder characteristics of this ultra-fine powdered silicic acid are that the oil absorption is 30 to 70 ml, whereas general inorganic fillers show more than 200 ml/100 g.
It is small at ml/100g, and the sedimentation volume is 20% smaller than that of the former.
It is characterized by being smaller at 8-13ml/5g compared to ~80ml/5g. These values indicate the surface condition and shape of the fine powdered silicic acid, but ultimately mean that the powder is relatively spherical with few voids. Furthermore, it is characterized by a very sharp particle size distribution with an average particle diameter of 1 to 20 μm, and it is presumed that these factors work together to produce various effects. Also,
The above average particle size is 1 to 20μ, and the oil absorption is 30 to 70ml/
When using ultrafine powdered silicic acid with physical properties that differ from the conditions of 100 g and sedimentation volume of 8 to 13 ml/5 g, the light diffusivity, scattered light transmittance,
Defects appear in optical properties such as parallel light transmittance. The amount of ultrafine powdered silicic acid added to the thermoplastic plastic is preferably 0.3 to 3.0 phr. If the amount is less than 0.3phr, the effect of improving molding processability and imparting light diffusivity is difficult to be exhibited;
If the amount exceeds 3 phr, disadvantages such as adverse effects on mechanical properties and complete loss of transparency will become stronger. In the present invention, when imparting light diffusing properties, the type of thermoplastic plastic is limited to those having transparency, but the types of plastics used for this purpose include polyvinyl chloride, polystyrene, etc. , poly(meth)acrylic acid ester, polycarbonate, polyester, epoxy, and other homopolymers or copolymer resins with other components. In this case, the shape of the molded product can be applied not only to films and sheets by extrusion or calendar molding, but also to various shapes by injection molding, blow molding, injection molding, pressure molding, etc. The present invention will be explained in more detail in Examples below, and the following evaluation methods were used to measure the physical properties. Optical properties: A sample with a wall thickness of 2 mm prepared by a roll and press method was measured in accordance with ASTM-D-1003. Light diffusion: Expressed as the distance at which the shape of a 20W fluorescent lamp becomes invisible. Melt viscosity: Measured using a Koka type flow tester, load: 150 kg, and orifice size: 1 mmφ x 10 mm. Average particle size: Coulter counter method Oil absorption: JIS K5101 Sedimentation volume: Measure the volume by gently dropping 5 g of the sample into a graduated cylinder. Example-1 and Comparative Example-1 Vinyl chloride resin PVC (average degree of polymerization≒700) 100
2 parts of tin-based stabilizer (N-2000E), 0.3 parts of stearyl alcohol (Calcol 86), and various fillers according to Table 1. The mixture was kneaded for 3 minutes to form a rolled sheet with a wall thickness of approximately 0.5 m/m. Next, this rolled sheet was cut to a fixed size, stacked in a spacer, and pressure-formed for 6 minutes in a press set at 180°C to form a press plate with a wall thickness of 2 mm. The light diffusivity and optical properties of the press plate molded here were measured. The results are shown in Table 1, and the composition of the present invention not only has light diffusivity but also has a large total light transmittance (Tt), demonstrating the desired effect. On the other hand, the filler used in the comparative example could not exhibit light diffusivity, and could only show a small value of total light transmittance (Tt) of 70% or less.

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Claims (1)

[Claims] 1 Average particle size is 1~20μ, oil absorption is 30~70ml/
100 g, a thermoplastic composition characterized in that it contains 0.3 to 3.0 phr of ultrafine powdered silicic acid with a sedimentation volume of 8 to 13 ml/5 g.