JPH01115982A - Application sheet - Google Patents

Abstract

PURPOSE:To obtain the above sheet capable of satisfactorily carrying out application and stripping off, by forming a tacky expanded layer which is an expanded structure of an open-cell system having the surface coated with a skin layer with a constant peel adhesive force on the surface of a support. CONSTITUTION:The objective sheet obtained by forming a tacky expanded layer 2 having an expanded structure of open-cell system having the surface coated with a skin layer 20 having the surface with fine vent holes (preferably 30-100mum average pore diameter) and 25-250g/cm width peel adhesive force at 180 deg. of the surface on the surface of a support 1.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an adhesive sheet that can be easily applied and peeled off.

<Prior Art and its Problems> Various types of adhesive sheets have been put into practical use in which a pressure-sensitive adhesive layer is provided on the support surface depending on the intended use. In general, such sheet-like materials are thin-walled film-like supports and are highly flexible, which may cause minute wrinkles when pasted, but they have sufficient adhesive strength to the adherend surface. If the adhesive force is high to achieve this, it is difficult to adjust or correct the position during pasting work.

Furthermore, there is a problem that air may be trapped at the interface between the adherend surface and the adhesive layer during pasting, and this air becomes bubbles after pasting, making the appearance of the sheet unsightly. Furthermore, due to changes in the adhesive over time, when such a sheet is removed from the adherend surface, the adhesive may remain attached to the adherend surface and stain the adherend surface. There is a problem.

<Means for solving the problems> The present invention has been made in order to provide an adhesive sheet that solves all the problems as described above, and the purpose is to:
A sheet-like product comprising an adhesive foam layer provided on a support surface, the surface of the adhesive foam layer being covered with a skin layer having fine ventilation holes, and the adhesive strength of the surface when peeled off at 180 degrees is 25. This is achieved by having an open cell foam structure with a width of ~250 g/ctrr, and will be described in detail below with reference to the accompanying drawings.

<Structure and operation of the invention> In the drawings, ■ indicates sheets and films mainly made of synthetic resins such as polyester, polychlorinated beer, and polyethylene, and/or rubbers such as butyl rubber, urethane rubber, and acrylic rubber (foams of these ) or cloth,
A support made of nonwoven fabric, paper, etc. 2 is the support 1
It is an adhesive foam layer provided on one side of the . Layer 2 is made of a rubber-like adhesive polymer, typically an acrylic copolymer emulsion, which is foamed by mechanical stirring or the like, applied onto the support 1, and then crosslinked by means such as heating. It can be formed by

In the above, as the acrylic copolymer emulsion, a copolymer of acrylic ester or a copolymer of acrylic ester and a monomer having an ethylenically unsaturated bond is selectively used.

Examples of acrylic esters include ethyl acrylate, butyl acrylate, octyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
Polymethylolpropane acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, etc. are used, and monomers having ethylenically unsaturated bonds include acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride,
Monomers having double bonds such as itaconic acid, allyl alcohol, butadiene, isoprene are used.

The solid content is usually 40 to 65% by dispersing such a monomer in a dispersion medium such as water and polymerizing it, or by dispersing a polymerized monomer in advance in a dispersion medium. Emulsify to give weight%. In this polymerization, known emulsifiers, emulsion stabilizers, polymerization initiators, and the like are appropriately added. The acrylic copolymer emulsion configured in this way is a self-crosslinking type or a reactive crosslinking type polymer, and in the case of a reactive crosslinking type, it is usually a crosslinking polymer such as an alkylated methylol melamine type, epoxy type, or isocyanate type. The agent is added in an amount of 1 to 10 parts by weight based on 100 weight parts of the solid content of the emulsion. In addition, the emulsion may contain crosslinking accelerators such as organic amine salts, inorganic metal salts, and ammonium salts, polyvinyl alcohol,
Thickeners such as methylcellulose, sodium alginate, carboxylated ethyl acrylate, anionic fatty acid soaps, sulfates, sulfonates, foam stabilizers such as nonionic polyoxyethylene alkylphenol ethers, ammonia, caustic soda, caustic potassium, etc. Contains a pH adjuster, etc., and usually has a viscosity of 30 to 300 poise (at, 2
0°C).

Then, the adhesive polymer thus blended is mechanically stirred or otherwise foamed to a foaming ratio of usually 1.1 to 10 times, and the foamed product is placed on the support 1. The emulsion is coated uniformly to a thickness of about 50 to 1000 μm and dried by heating at 80 to 180° C. for about 3 to 60 minutes to volatilize the dispersion medium of the emulsion and moderately crosslink the polymer component. The adhesive polymer formed by foaming and crosslinking in this manner forms a foam layer having appropriate adhesiveness, and the surface thereof is covered with a skin layer 20 having a dense foam structure. In the foamed layer 2, by foaming the adhesive polymer in advance as described above, the size of foaming before heating does not substantially change, so the thickness of the layer increases during heating and drying. It has the advantage that it is less likely to exceed the desired thickness or the surface of the foam layer will become uneven, and can be made into an adhesive foam layer that is relatively thin and has a smooth surface structure. The adhesive foam layer 2 configured in this manner is a semi-crosslinked product in which the degree of crosslinking of the polymer is adjusted to preferably have a gel content of 60 to 90%, particularly preferably 70 to 85%.

Here, the gel content (%) is determined as follows.

A certain amount of the crosslinked polymer was collected and immersed in a solvent (ethyl acetate) for 5 days, filtered and separated using a 70 mesh mesh material, and the solid content was dried at 100°C for 2 hours. The weight of the solid content after drying is measured, and the gel content (%) is calculated using the following formula.

The texture of the adhesive foam layer 2 can be changed in various ways by changing the degree of crosslinking indicated by the gel content (%), but if the degree of crosslinking (gel content) is too low, the structure of the layer 2 The foamed structure has no stiffness, is too soft and easily deforms physically, and is not chemically stable, so its adhesive properties tend to change over time, which is undesirable. In addition, if the degree of crosslinking (gel content) is too high, it is undesirable because the flexibility is poor and it is difficult to follow and adhere to the uneven surface of the adherend, and the adhesive strength is lost and it is difficult to obtain the desired adhesive properties. . In layer 2, when the adhesive polymer is heated and dried as described above, the dispersion medium evaporates and many of the pore walls of the foam structure become interconnected, forming an open-cell structure. A large number of fine through-holes are formed in the surface skin layer, but by appropriately crosslinking the polymer component as described above, layer 2 is made into an open-cell foamed composite fiber with appropriate flexibility. In this case, the open cell ratio (volume ratio) in the foamed structure is at least 50%, preferably 7.
The skin layer 20 has an open cell structure of 0 to 100%, and the average pore diameter of the vents formed in the skin layer 20 is at least 20 μm.
It is desirable that the thickness be 30 to 100 μm or more, preferably 30 to 100 μm. If the open cell ratio in the foam structure and the pore diameter of the vent holes are less than these, it is not preferable because the air trapped in the adhesive interface during pasting cannot be sufficiently discharged. Further, as an index of the flexibility of layer 2, it is desirable that the value indicated by 50% compressive load is 3.0 kg/cffl or less.

By adjusting the degree of crosslinking of the polymer as described above, the skin layer 20 formed on the surface has a tackiness to the touch (
Although there is almost no finger tack, it develops a certain adhesive force to the surface of the adherend by applying pressure, and this adhesive force has an adhesive force of 25 to 250 g/am width when peeled off at 180 degrees. Preferably 25-150g/
c+++ width (peeling speed 300mm/min, 2
It is important that the temperature is 0°C x 60% R,I (,). If this adhesive strength is lower than 25g/cm width, it will be difficult to obtain sufficient adhesive strength to adhere the sheets, and if it is higher than 250g/c+a width, it will be difficult to adjust the position of the sheet during pasting work. This is not preferable because it becomes difficult to make corrections, and when the sheet is peeled off from the surface of the adherend after pasting, the adhesive substance constituting the foam layer tends to remain attached (this is not desirable. When stretched, layer 2 deforms or breaks,
In order to effectively prevent this, the tensile strength of layer 2 is set to 3.0 kg.
It is desirable to set it to /ci or higher.

Note that the adhesive foam layer 2 may be bonded onto the support 1 via an adhesive layer (not shown).

The adhesive sheet of the present invention configured as described above can be used as a display material by being applied to glass or steel parts such as automobiles, windows, various display cases, perches, walls, etc. It can be applied to the surface of metal, resin molded objects, etc. and used as a surface protection material for punching, cutting, drawing, and bending, and has a wide range of uses. In addition, when used as a surface protection material, the thickness of the support 1 is 2.
A thin and flexible synthetic resin film of about ~100 μm is selected, and the thickness of the layer 2 is preferably about 5 to 500 μm, and the elongation of the support 1 is 100% or more, and the tensile strength of the layer 2 is A combination of 5.0 kg/cff1 or more maximizes the effects of the present invention.

<Example> Next, an example of the present invention will be described. The text middle part means the weight part.

100 parts solid content of an acrylic copolymer emulsion with a solid content of 59% by weight, in which a copolymer obtained by polymerizing ethyl acrylate, butyl acrylate, and acrylonitrile in a weight ratio of 28:63:9 is dispersed in water. Add the following substances to

Methoxymethylolmelamine 5 parts Organic amine salt 1 part Carboxylated ethyl acrylate 3 parts Ammonium stearate salt 3 parts Ammonia
Viscosity 100 poise (a
After foaming the adhesive polymer of t, 20"C) to a foaming ratio of approximately twice by mechanical stirring (approximately 1000 revolutions/min) using a portapul mayonnaise mixer, this was foamed to a thickness of 6 μm.
Thickness 17 on polyester film (130% elongation)
After applying it uniformly to 0 μm and preheating at 80°C for 2 minutes,
Cross-linked by heating and drying at 150°C for 5 minutes to form a skin layer with fine ventilation holes on the surface and a thickness of 170 μm.
An adhesive foam layer was obtained.

The sheet-like product thus formed had a smooth surface of the foam layer, and had an open-cell structure that was moderately flexible and firm. When the physical properties of this foamed layer were measured under the conditions described in the text, the results shown in Table 1 were obtained.

The thickness of the adhesive sheet having each of these physical properties is 0.4
It was attached to the surface of a stainless steel plate. The sheet had minute wrinkles and air bubbles, but by adjusting the position, it was able to be pasted beautifully. Next, the stainless steel plate with the surface protected in this way was punched out into a circular shape with a diameter of 5 cm. As a result, although the pasted sheet was stretched at the edges of the punched piece, visual inspection of the adhesive foam layer revealed no broken parts, and no adhesive substance was observed to adhere after the sheet was peeled off. There wasn't.

<Effects of the Invention> Since the present invention is configured as described above, its effects are as follows. That is, 1) The surface of the adhesive foam layer provided on the support surface is covered with a skin layer composed of a densely foamed structure, and the adhesive strength of the surface when peeled off at 180 degrees is 25 to 250.
By having a width of g/cm, the position of the sheet can be easily adjusted and corrected during pasting.

2) The adhesive foam layer can absorb fine wrinkles caused by open-cell flexible foam fibers, and by pressing the sheet surface, the foam layer's cushioning ability also absorbs unevenness on the surface of the adherend. It also follows closely and can achieve sufficient adhesive strength.

3) Air trapped in the adhesive interface during pasting is absorbed into the foam tissue through the fine ventilation holes in the skin layer, and can be discharged to the outside due to the open cell structure of the foam tissue.

4) The adhesive foam layer is covered with a skin layer that has excellent surface strength and has weak adhesive properties, so there is no possibility that adhesive substances will remain attached when it is peeled off from the adherend surface after pasting. There are no or only a few.

It has the following effects and its practical value is high.

[Brief explanation of the drawing]

The drawing is a partial side view showing an example of the invention. 1...Support 2...Adhesive foam layer 20...
・Skin layer

Claims (1)

[Claims] A sheet-like product comprising an adhesive foam layer provided on a support surface, the surface of the adhesive foam layer being covered with a skin layer having fine ventilation holes, and the adhesive strength of the surface when peeled off at 180 degrees is 25. An adhesive sheet with an open cell foam structure having a width of ~250 g/cm.