JPS6334827B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an overlay sheet, particularly an overlay sheet suitable for covering the surface of particle board. Particle board is made of small pieces of wood hardened with adhesive, and a plastic overlay sheet is attached to the surface to enhance its aesthetic appearance. A rigid polyvinyl chloride sheet is suitable for this purpose. However, while the surface layer of particle board is densely packed with small pieces of wood, the inside layer is packed with large pieces of wood. As a result, an internal rough structure appears on the end (side surface), resulting in unevenness, making it difficult to adhere the overlay sheet to the end. Conventionally, countermeasures have been taken to solve this problem, such as applying a thick layer of adhesive to the end of the wood, but this is not very effective, and the sheet covering the end of the wood lifts up, spoiling the appearance.
Furthermore, the problem of the raised sheet cracking or fraying still remains. As a result of various studies on this problem, the inventors of the present invention found that polyvinyl chloride sheets have a strong repulsive force that tends to return to their original shape even if they are bent once, and that this repulsive force is a major cause of poor bonding. That is, as shown in FIG.
Even if an attempt is made to bend the sheet 2 along the same direction and bond it together, the sheet 2 tries to return to its original shape, causing the sheet 2 to rise slightly, making it impossible to obtain sufficient adhesive strength. A similar problem also occurs when a sheet is bonded to the V-groove 13 provided in the board 1. The present invention solves the above-mentioned problems by using a sheet that has low resilience when folded. The present invention provides an overlay sheet formed by forming folding grooves on a polyvinyl chloride resin sheet containing 5 to 70 parts by weight of inorganic filler particles within the range of 5 to 70 parts by weight and having a Kratschberg softening temperature of 45° C. or higher. The present invention will be specifically explained below. In addition, in the following explanation, "part" indicating the mixing ratio is
Represents "part by weight". The overlay sheet of the present invention contains 100 parts of polyvinyl chloride resin (PVC) and 5 to 70 parts by weight of inorganic filler particles with a particle diameter of 2 to 10 m, and has a Kratschberg softening temperature of 45°C or higher. obtained from the composition. PVC may be an ordinary molding resin, and either a vinyl chloride homopolymer or a vinyl chloride-based copolymer can be used. The inorganic filler particles added to PVC are used to reduce the resilience when the sheet is bent, and include calcium carbonate, silica, clay, talc, kaolin, magnesium carbonate, magnesium oxide, aluminum hydroxide, etc. These particles can be used alone or in combination of two or more. In order to reduce the repulsion of the sheet, particles with a particle diameter (average value of major axis and minor axis) of 2 μ or more are effective, and particles smaller than this alone cannot provide a sufficient effect. On the other hand, if the particle size exceeds 10μ, the physical properties of the sheet will be significantly reduced and pinholes may be formed in the sheet, making it unsuitable for this purpose, especially when printing wood grain patterns etc. on the sheet. spoil the appearance. Therefore, the particle size should be 2 to 10μ, especially 2μ.
~8μ is preferred. The amount of particles added should be within the range that can reduce repulsion in order to maintain the strength of the sheet.
Although it is preferable to reduce the amount as much as possible, 5 parts or more is necessary. Also, if the amount of particles exceeds 70 parts,
The original strength of PVC is greatly impaired, causing problems in practical use. From the viewpoint of both the reduction in repulsion and the strength of the sheet,
5 to 50 parts, preferably 8 parts of particles with a particle size of 2 to 10μ
-30 parts is added, and when particles with a particle size of less than 2 μm are used together, the total amount of particles is preferably 70 parts or less, preferably 40 parts or less. In addition, the flexibility temperature of the PVC sheet
T _f (according to JIS K6745) shall be 45°C or higher, that is, the so-called hard to semi-hard range. T _f
Soft sheets at temperatures below 45°C will soften and deform when used in the summer or in high-temperature rooms, and the unevenness of the base (particle board) will appear on the sheet surface. There is no particular upper limit to T _f , but ordinary PVC can only provide temperatures up to about 75°C. T _f is almost determined by the amount of liquid additives, especially plasticizers, so in order to make T _f 45℃ or higher, for example, DOP
In the case of , the amount is approximately 10 parts (for 100 parts of PVC)
You can do the following. The sheet also typically has an opaque colorant added to it so that the particleboard cannot be seen through. The overlay sheet of the present invention is as described above.
A PVC composition (containing stabilizers, lubricants, impact modifiers, etc. as necessary) is formed into a sheet with a predetermined thickness, preferably 50 to 500μ, by extrusion or calendering, and the sheet is coated with a first It is obtained by forming a bending groove as shown in FIG. The depth of this groove needs to be at least 10% of the thickness of the sheet, and is preferably at most 70%. As a method for forming the grooves, a method such as pressing a groove-forming blade against the sheet can be adopted. Once the sheet of the present invention is folded along the folding groove, it has a small resilience to restore its original shape, so it adheres well to the end of the board, etc., and a good adhesion state can be obtained. Example: To 100 parts of PVC homopolymer (average degree of polymerization 700),
From a composition (T _f 68°C) containing 10 parts of MBS resin, 2 parts of DOP, 5 parts of lead-based stabilizer and particles of the type and amount shown in Table 1, the thickness was measured by calendering.
A 200μ sheet was produced. A 10 cm square sample was taken from the sheet, folded in half, and held under a 1 kg weight for 1 minute. The weight was then removed and the recovery angle of the sheet was measured every hour. The results are also shown in Table 1.

【table】

[Table] Sheet No. 2 contains titanium oxide as a white pigment, but its particle size is small, and sheet No. 3 has a small amount of particles, so neither of them has sufficient effects. On the other hand, sheets Nos. 4 to 9 of the present invention have significantly smaller recovery angles than No. 1. In addition, when we formed grooves with a depth of 100μ in each sheet and covered them with particle board, No. 1 to
Sheet No. 3 had poor adhesion to the wood end, and some sheet lifting was observed, whereas sheets No. 4 to 9 of the present invention adhered closely to the wood end and exhibited good adhesive strength and appearance.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating how to use the overlay sheet of the present invention. 1... Particle board, 2... Overlay sheet, 12... Wood end, 21... Groove for bending.

Claims (1)

[Claims] 1. For 100 parts by weight of polyvinyl chloride resin, add 5 to 70 inorganic filler particles with a particle size of 2 to 10 μm.
Contains parts by weight and has a Kratschberg softness temperature of
An overlay sheet made by forming folding grooves on a polyvinyl chloride resin sheet that is heated to 45°C or higher.