JPH0137266B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a decorative board in which a decorative polyvinyl chloride sheet is adhered to the surface of a steel plate or wood plywood, and a method for manufacturing the same. Boards made by adhering colored or patterned polyvinyl chloride sheets to one or both sides of steel plates or wood plywood (hereinafter referred to as vinyl chloride decorative boards) are used in the manufacture of furniture and electrical equipment, or as building materials. However, a surface protection film is often adhered to the decorative surface of a decorative board in order to prevent damage and contamination at various stages from the manufacture of the decorative board to the start of use. The surface protection film should be applied in a moderate amount to the extent that it will not peel off during normal handling or processing of the decorative board, but to the extent that it can be easily peeled off when the decorative board or a structure using it, such as a building, is started to be used. It goes without saying that it must be bonded to the decorative board with an adhesive strength of There should be no ``glue residue'' left after applying the adhesive. However, conventional surface protection films have problems when used to protect the surface of polyvinyl chloride sheets (hereinafter referred to as vinyl chloride sheets). In other words, there are two types of surface protection films: a pressure-sensitive type in which a pressure-sensitive adhesive is applied to a base film, and a heat-sensitive type in which a low-melting thermoplastic resin is laminated on a base film. The ones of
It has the disadvantage that the adhesion is unstable after being bonded to the decorative PVC sheet. For example, pressure-sensitive protective films typically use acrylic or rubber-based pressure-sensitive adhesives, but these adhesives are easily affected by the plasticizer in polyvinyl chloride, and after bonding, After two weeks, not only does the adhesive force deteriorate, but when the protective film is removed, the adhesive remains on the PVC sheet side, leaving the surface dirty. Furthermore, in the case of heat-sensitive protective films that use ethylene/vinyl acetate copolymer resin (or a mixture of this and polyisobutylene), ethylene/ethyl acrylate copolymer resin, or the like as an adhesive, the adhesive strength deteriorates significantly over time. As a means to solve the above-mentioned unique problems in protecting the surface of PVC sheets, Japanese Patent Publication No. 1983-6309 discloses that an ethylene polymer mixed with a chlorine-containing polymer with a solubility parameter of 8.0 to 11.0 is used as an adhesive. A method for use is disclosed. However, although this method is somewhat effective in stabilizing adhesive strength, the chlorine-containing polymer thermally decomposes during the manufacturing process of the surface protection film and generates corrosive gas, resulting in equipment corrosion and environmental pollution. This is not a preferable method because it not only causes a problem but also generates toxic and corrosive gas when the protective film removed from the decorative board is incinerated. The present invention solves the above-mentioned drawbacks of conventional surface protection means for PVC decorative boards, and a polyolefin surface protection film is bonded with an ethylene/vinyl acetate copolymer resin mixed with a plasticizer for polyvinyl chloride. The present invention provides a PVC decorative board and a method for advantageously manufacturing the same. The ethylene/vinyl acetate copolymer resin used as the adhesive for the surface protection film in the present invention includes:
Preferably, the vinyl acetate content is 20 to 50% by weight. If this value is less than 20% by weight, not only the adhesive strength is too low, but also the required amount of polyvinyl chloride plasticizer cannot be mixed uniformly. while 50
If the amount exceeds % by weight, it is difficult to laminate the base film of the surface protection film by melt extrusion molding. Further, it is desirable that the melt index of this resin is about 2 to 50 in a state in which a plasticizer described below is mixed therein. Plasticizers for polyvinyl chloride mixed into ethylene/vinyl acetate resin include phthalic acid derivatives such as dioctyl phthalate, adipic acid derivatives such as dioctyl adipate, azelaic acid derivatives such as dioctyl azelate, and dioctyl sebacate. sebacic acid derivatives, maleic acid derivatives such as dioctyl maleate, fumaric acid, trimellitic acid, citric acid, itaconic acid,
Among compounds that can be used as plasticizers for polyvinyl chloride, such as derivatives of oleic acid, ricinoleic acid, stearic acid, various sulfonic acids, phosphoric acid, and glycolic acid, those that are liquid at room temperature are used. Monomethyl itaconate, diethylene glycol distearate, and the like, which are solid at room temperature, have no effect when used for reasons that are unclear. The mixing effect is greatest when the plasticizer is the same as the plasticizer most abundantly contained in cosmetic PVC sheets (so-called primary plasticizer), but it does not have to be the same. The mixing ratio of plasticizer to ethylene/vinyl acetate copolymer resin is 2 to 30
% by weight, preferably 5-15% by weight. The polyolefin film used as the base material of the surface protection film has a melt index of 2 to 2.
50 (preferably 6 to 15) low-density polyethylene and medium-density polyethylene are preferred from the viewpoint of physical properties. The adhesive force between the surface protection film and the decorative board is generally about 50 to 200g/25mm (at most 500g/25mm).
mm) is considered appropriate, and the adhesion conditions will be changed depending on the characteristics of the adhesive so that the decorative board of the present invention has an adhesive force within the above range, but as long as there is no risk of natural peeling. , there is no problem even if the adhesive force is lowered to about 20g/25mm. In the decorative board of the present invention, the decorative PVC sheet and the steel plate, wood plywood, etc. to which it is adhered are:
It is not limited in any way. The decorative board of the present invention as described above uses a polyolefin film as the base material of the surface protection film and an ethylene/vinyl acetate copolymer resin mixed with a plasticizer for polyvinyl chloride as an adhesive. Although the mechanism of action of the agent has not yet been confirmed, the adhesion of the protective film is stable for a long time, and therefore the protective film does not peel off naturally even under harsh conditions, and the protective film does not peel off after being peeled off. No adhesive from the film will remain and stain the surface of the decorative board. Furthermore, the protective film after being removed from the decorative board has the advantage of being easy to dispose of, as the adhesive layer is non-stick and does not generate corrosive or irritating gases even when incinerated. . The decorative laminate of the present invention may be manufactured by a conventional method in which a PVC decorative laminate is manufactured and then a surface protection film is bonded to the plate, but a particularly advantageous manufacturing method is the manufacturing method according to the present invention as detailed below. It is. In the manufacturing method of the present invention, as shown in FIG. 1, a laminated sheet is prepared in which a surface protection film 2 is adhered in advance to a decorative PVC sheet 1 to be adhered to a substrate such as a steel plate or wood plywood. However, numeral 3 in the figure is an adhesive layer of the above composition for use as a protective film, 1a is a surface that becomes the surface of the decorative board, and 1b is a surface that is bonded to the substrate. This laminated sheet may be manufactured by any method, but the following are particularly preferable because there is little strain left in the laminated sheet and it is less likely to spontaneously peel off even with low adhesive strength. It is manufactured by a method such as That is, the polyolefin resin that serves as the base material of the surface protection film and the adhesive component are heated and melted in separate extruders, and then the melts are combined into a layer and extruded through a T-die to form a film by a so-called co-extrusion method. The resulting laminate of polyolefin and adhesive, while still in a molten state, is pressed onto a decorative PVC sheet in the arrangement shown in FIG. In the manufacturing method of the present invention, a laminated sheet as shown in Fig. 1 is adhered to a substrate such as steel or wood plywood with surface 1b as the adhesive surface. You can do it in the same way as in the case. FIG. 2 shows the decorative board of the present invention made in this manner, where 4 is a substrate and 5 is an adhesive used to bond the laminated sheet of FIG. 1 to the substrate 4. The advantages of the manufacturing method of the present invention as described above are as follows. Since the decorative PVC sheet is already protected by a protective film at the time it is bonded to the substrate, surface damage during the bonding process can be avoided. In order to adhere a heat-sensitive surface protection film to a PVC decorative board using the conventional method, the entire decorative board, which has a large heat capacity, must be heated to a temperature that can be bonded, which not only consumes a large amount of heat but also makes uniform heating difficult. Therefore, there was a problem in that adhesive strength was likely to be uneven. In the case of PVC steel plates, there is a method to reduce heat consumption by adhering a surface protection film immediately after adhering the PVC sheet to the steel plate in a heated state, but in this case too, adhesion spots may occur due to temperature unevenness. This is unavoidable, and the adhesion conditions are restricted due to the process of adhering the protective film being incorporated into the PVC steel sheet production line. Therefore, the advantage of the heat-sensitive type is that the adhesion force can be adjusted by changing the heating temperature and pressure bonding time. do not have.
In contrast, in the method of the present invention, the protective film, which requires delicate adjustment of adhesive strength, is bonded to the thin PVC sheet before being bonded to the substrate, so all the drawbacks of the conventional method described above are avoided. It will be resolved. Previous attempts have been made to bond a heat-sensitive surface protection sheet to a decorative PVC sheet before adhering it to a substrate to create a laminated sheet, but this method allows the adhesive to be bonded by the transfer of plasticizer in the PVC sheet immediately after lamination. However, the method of the present invention has the drawback that the adhesion strength of the protective film on the product varies depending on the length of storage period in the laminated sheet state as the adhesive strength begins to decrease, making it impractical. This problem has been solved by using a unique adhesive that exhibits very little reduction in adhesive strength. The present invention will be explained below with reference to Examples. The adhesive strength shown in Table 1 is for a sample with a width of 25 mm.
Tensile speed 300mm/min, peel angle 180゜, 23℃・65%RH
Measured using Toyo Baldwin Tensilon under the following conditions. Example 1 Base material: polyethylene with a density of 0.920 and MI10. Adhesive: MI5 ethylene/vinyl acetate copolymer resin with vinyl acetate content of 28% by weight and 10% by weight of dioctyl phthalate. The above materials for surface protection films are co-extruded into laminates with a thickness of 50 μm for the former and 20 μm for the latter, and while they are still in a molten state, a PVC sheet (as a plasticizer) is containing dioctyl phthalate) with the adhesive layer on the inside. At that time, eight types of laminated sheets (a
-h) were produced. Each laminated sheet was stored at room temperature for 30 days and then bonded to a steel plate to produce a PVC steel plate. No peeling occurred. Example 2 Base material: polyethylene with a density of 0.924 and MI10. Adhesive: MI5 ethylene/vinyl acetate copolymer with a vinyl acetate content of 20% by weight and 5% by weight of dioctyl adipate. The above materials for the surface protection film were prepared in the same manner as in Example 1, with the former having a thickness of 30 μm and the latter having a thickness of 30 μm.
A laminate with a thickness of 40 μm is formed and is further pressure-bonded to a PVC sheet containing dioctyl phthalate. At that time, by changing the pressure bonding conditions, two types of laminated sheets (i,
j) was manufactured. After storing each laminated sheet at room temperature for 30 days, it was adhered to plywood to produce decorative PVC plywood. During adhesion and cutting of the obtained decorative plywood, natural peeling of the surface protection film did not occur. Example 3 Base material: polyethylene with a density of 0.918 and MI10. Adhesive: 45% by weight of vinyl acetate, MI2 ethylene/vinyl acetate copolymer resin mixed with 20% by weight of dioctyl phthalate. The above materials for the surface protection film were prepared in the same manner as in Example 1, with the former having a thickness of 40 μm and the latter having a thickness of 40 μm.
A laminate with a thickness of 30μ is formed, and is further pressure-bonded to a PVC sheet containing dioctyl phthalate. At that time, by changing the pressure bonding conditions, two types of laminated sheets (k,
l) was produced. The obtained laminated sheet was then adhered to a steel plate to produce a PVC steel plate. [Comparative Test of Adhesive Strength] Table 1 shows the results of examining the adhesive strength between the protective film and the cosmetic PVC sheet and its change over time for the products according to each of the above examples. However, for convenience, the test was conducted on a laminated sheet that was not adhered to a substrate, and the change over time was accelerated by applying a load of 10 g/cm ² and heating to 40°C or 65°C. Comparative Examples 1 and 2 shown in the table were manufactured by the same manufacturing method as each Example and had the following configuration. Protective film base material: Same as Example 1. Adhesive: MI5 ethylene/vinyl acetate copolymer resin with vinyl acetate content of 28% by weight. Layer thickness 20μ. PVC sheet: Same as Example 1.

[Table] As is clear from Table 1, in the accelerated heating test, the comparative example quickly lost its adhesive strength, whereas the inventive product still peeled naturally even though its initial strength was quite low. The adhesion strength was maintained to the extent that no damage was caused. Furthermore, when the surface of the PVC sheet was observed after measuring the adhesive strength, no stains or the like were observed at all.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a laminated sheet used to manufacture the decorative laminate of the present invention, and FIG. 2 is a sectional view of the decorative laminate of the present invention made using the laminated sheet of FIG. 1. 1: Decorative PVC sheet, 2: Surface protection film, 3, 5: Adhesive layer, 4: Substrate.

Claims (1)

[Scope of Claims] 1. A substrate made of a steel plate or wood plywood, a decorative polyvinyl chloride sheet adhered to at least one surface of the substrate, and a surface protection sheet adhered to the decorative polyvinyl chloride sheet to a peelable extent. A cosmetic with a surface protection sheet, which is made of a polyolefin in-film, and the polyolefin in-film is adhered to a cosmetic polyvinyl chloride sheet using an ethylene-vinyl acetate copolymer resin mixed with a plasticizer for polyvinyl chloride, which is liquid at room temperature. Board. 2. When manufacturing a decorative board in which a decorative polyvinyl chloride sheet is adhered to a substrate made of steel plate or wood plywood, and a surface protection film is further adhered to such an extent that it can be peeled off, the surface protection polyolefin film is a liquid polyvinyl chloride sheet at room temperature. A surface characterized by adhering a decorative polyvinyl chloride sheet to a substrate in the form of a laminated sheet, which has been previously adhered to the decorative polyvinyl chloride sheet with an ethylene-vinyl acetate copolymer resin mixed with a plasticizer for vinyl chloride. Manufacturing method of decorative board.