JPH025790B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive sheet that can be easily peeled off if necessary, and more specifically, after the sheet is laminated onto an adherend such as metal, glass, plastics, ceramics, or wood. , relates to an adhesive sheet having the characteristic that the sheet can be peeled off and removed from an adherend very easily by coating the sheet with water or a water-based paint at any time to moisten the sheet and further applying heat.

Adhesive tape has traditionally been widely used as masking sheets during plating and etching processes, protective sheets for various materials, masking sheets for printing and paint, and other temporary sheets. There is a drawback that the work of removing these sheets afterwards is complicated and requires a lot of time.

The present invention has improved these drawbacks, and can be used as various masking sheets, protective sheets, and other sheets for temporary fixing, but in all cases, it is extremely difficult to use. The feature of the present invention that can be easily peeled off from the adherend by applying water wetting and heating for a short time can be utilized.

Especially used as a masking sheet for painting,
This is particularly effective when the paint used is a water-based paint.

For example, when the releasable adhesive sheet of the present invention is used as a masking sheet for small pieces, the operator does not have to remove the masking sheet one by one, but rather moistens it with water and then heats it to stretch the sheet and change the molecular orientation of the film. As the unfixed polyvinyl alcohol film shrinks, the sheet is peeled off from the adherend, improving productivity.Also, since no adhesive remains on the adherend surface, adhesion is improved by removing residue. It does not cause any physical damage.

The releasable adhesive sheet of the present invention is a stretched polyvinyl alcohol film support that shrinks with water and heat and does not have fixed molecular orientation, or has a lower heat shrinkage rate and shrinkage rate with respect to water than the polyvinyl alcohol film. An adhesive layer is provided on a support formed by laminating a material with the polyvinyl alcohol film, and the adhesive force to the adherend is smaller than the deformation stress of the polyvinyl alcohol film support or the material laminated with the polyvinyl alcohol film. It is an adhesive sheet that is easily peeled off.

The present invention will be explained in detail below with reference to the drawings. 1 and 2 are sheets according to the present invention,
FIG. 1 shows a polyvinyl alcohol film 1 with an adhesive layer 3 provided directly on it, and FIG. This is a sheet in which an adhesive layer 3 is provided on a support made of a composite material using the following materials.

In the figure, the polyvinyl alcohol film 1 is stretched and the molecular orientation of the film is not fixed.
The sheet-like material 2 is a polyvinyl alcohol film having a certain degree of water resistance, and the sheet-like material 2 is a sheet-like material consisting of one layer or multiple layers (the figure shows the case of one layer), which is made of a different material. The adhesive layer 3 is an adhesive layer that adheres to the target adherend.

FIGS. 3 to 5 show the releasability of the sheet according to the present invention when wetted with water and heated. Fig. 3 shows the product of the present invention laminated to the adherend 4, and Fig. 4 shows the product of the present invention bonded to the adherend 4 after being moistened with water, causing the layer 1 of the product of the present invention to shrink and release from the adherend. This shows a state where peeling has occurred. FIG. 5 shows a case where heating is further applied, peeling progresses, and the contact area with the adherend is extremely reduced.

It is inconvenient for the polyvinyl alcohol film used in the present invention to be easily soluble in water; for example, it is made from polyvinyl alcohol with a degree of polymerization of 1700 and a degree of saponification of 99 mol% or more, and is subjected to so-called heat treatment in the film forming process. It is desirable that the film be made into a film with water resistance. or,
The polyvinyl alcohol film for this purpose must shrink when it is wetted with water or water-based paint, and must also shrink when subjected to heat treatment. Therefore, it is necessary that the film is not a normal cast film but has been stretched by a factor of 2 to 5 times, but it must not be a so-called heat-set film that has a fixed molecular orientation. However, it does not matter whether the film is uniaxially stretched or biaxially stretched.

Materials that can be used when laminating one or more layers include various plastic films such as polyester, polypropylene, nylon, and polyvinyl chloride, various foams made from these materials, and pigments and other fillers. The material may be appropriately selected from films containing these, composites thereof, kraft paper, synthetic paper, etc. Further, even if it is a metal foil, it can be put to practical use because in combination with a polyvinyl alcohol stretched film, curl release can be obtained by wetting with water and heating, as shown in FIGS. 4 and 5.

On the other hand, the material for the adhesive layer that can be used in the present invention is not particularly specified in relation to the support and the adherend, but it is possible to adhere to the adherend at room temperature or by heating, and it is easy to adhere to the adherend. Considering the releasability and the non-transferability of the adhesive, the adhesive must have a relatively low adhesive force, low peeling force, high collective force, and an adhesive force smaller than the deformation stress of the support. For example, acrylic resin, polyester resin, polyurethane resin, silicone resin, natural rubber, synthetic rubber, epoxy resin, alkyd resin, polyvinyl acetate resin, etc. can be used.

Examples of the present invention will be shown below. The sheets of the present invention in the Examples have the configuration shown in FIG. 6 or FIG. 7, and in each Example, various cases are shown in which each layer of the sheet and the type of adherend are changed.

Example 1 The structure of the sheet in this example is 1 in FIG.
2 is a polyvinyl alcohol film (polymerization degree 1700, saponification degree 99.9 mol%, 20 μm) whose molecular arrangement is not fixed while being expanded approximately 3.5 times in the vertical direction, 2 is a synthetic paper (Yupo SG-60, Oji Yuka Co., Ltd. 60 μm) , 3 is a polyester resin adhesive layer (20 μm), and 5 is a polyurethane adhesive layer used for bonding the polyester alcohol film and synthetic paper. Further, 6 is a release paper (60 μm).

The sheet is manufactured by first laminating a polyvinyl alcohol film and synthetic paper together using a dry lamination method. Separately, a release paper 6 was coated with a polyester adhesive (Toyobo, Byron 300S) 3 and dried, and the product of the present invention was bonded to the synthetic paper side of a support on which a polyvinyl alcohol film and synthetic paper were bonded. Created. Cut the sheet obtained in this way into small pieces of approximately 10 cm x 10 cm, and place them on an iron plate (500 μm).
It was pasted on. Next, a water-based paint was applied onto the sheet to a thickness of about 200 μm to cover the sheet. Fifty such test pieces were prepared. Approximately 1
After seconds, all 50 pieces started to shrink, so that the area where the water-based paint layer covered the sheet cracked along the shape of the sheet, and when further heated to 120°C, the sheet The curl became so large that it peeled off from the iron plate and fell off with just a slight vibration. No adhesive residue was found in the area to which the sheet had been adhered.

Example 2 The structure of the sheet in this example is as follows: In Fig. 6, 1 is a polyvinyl alcohol film (20 μm) stretched approximately three times in the vertical direction and the molecular orientation of the film is not fixed, and 3 is an acrylic film. Adhesive layer (20 μm), 6 is release paper (60 μm). Acrylic adhesive: 100 parts of butyl acrylate, 20 parts of methyl acrylate, 10 parts of hydroxy acrylate
The average molecular weight is 300,000.
It is.

The sheet was prepared by coating a release paper with the acrylic adhesive and laminating it with the polyvinyl alcohol film to prepare a sample. The sample is 10mm x 10
Cut into mm size, aluminum plate (100μm)
After 24 hours, the sample was moistened with water and heated to 120°C.
All of the adhesives were peeled off and no adhesive was left on the aluminum plate.

As described above, the releasable adhesive sheet of the present invention can be easily peeled off from the adherend by water and heating for a very short time, so it is especially useful as a masking sheet or temporary adhesive when applying water-based paint. However, it is extremely effective when water treatment and heat treatment are performed in the subsequent process and it is necessary to remove it once it has been adhered to the adherend. It is highly effective because it does not cause any damage.

[Brief explanation of drawings]

Figures 1 and 2 are schematic cross-sectional views of the sheet of the present invention, Figure 3 is a diagram of the sheet of the present invention adhered to an adherend, and Figures 4 and 5 show that the sheet of the present invention is water resistant. 6 and 7 are schematic cross-sectional views of the sheets produced in each example. 1...Polyvinyl alcohol film that has been stretched but the molecular orientation of the film is not fixed;
2... Sheet-like material laminated with one layer or multiple layers,
3... Adhesive layer, 4... Adherent, 5... Adhesive layer, 6...
Release paper or release film.

Claims (1)

[Claims] 1. On a support made of a polyvinyl alcohol film that has been stretched and has not fixed the film molecular orientation, or on one side of the polyvinyl alcohol film, the shrinkage rate and heat shrinkage rate when wetted with water are lower than that of the polyvinyl alcohol film. Peelability, characterized in that an adhesive layer is provided on the laminated surface of a support in which small materials are laminated in one or more layers, the adhesive layer having an adhesive force to an adherend that is smaller than the deformation stress of the support. Adhesive sheet.