JPS60181183A - Double-sided adhesive sheet - Google Patents

Abstract

PURPOSE:The titled sheet, obtained by laminating a reaction product between a liquid diene based polymer and a polyisocyanate on a base material, having improved tackiness and creep resistance, capable of withstanding repeated use of peeling, reclaimable for use, and useful for dust removing tools. CONSTITUTION:A double-sided adhesive sheet obtained by laminating an adhesive layer consisting of a reaction product between (A) a liquid diene based polymer, e.g. polybutadiene homopolymer having 600-10,000 number-average molecular weight, having at least two active hydrogen groups, e.g. hydroxyl groups, in the molecule on at least one side of a base material, e.g. a polyester film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an adhesive sheet, and more specifically, it has extremely excellent creep resistance (characteristic of extremely large supporting capacity) and stable cohesive force even under temperature changes. The present invention relates to a double-sided adhesive sheet in which an adhesive layer having a slight adhesiveness that is stable over a wide range of temperatures is laminated on at least one side of a base material.

(Background of the invention) Conventionally, double-sided adhesive sheets include NR and IIR.

The base material is coated with or impregnated with a rubber adhesive mainly composed of SBR, CR, NBR, SIS block copolymer, etc., or the double-sided rubber adhesive sheet is made mainly of 2-ethylhexyl acrylate or butyl acrylate. Although it has a high adhesive strength and has excellent adhesive properties that can adhere to non-polar substances, it has the disadvantage that the cohesive force and creep strength of the adhesive layer decreases significantly at high temperatures, resulting in poor durability. have. Therefore, it is unsuitable for applications that require constant and stable creep strength over a wide range of temperatures from winter (low temperature) to summer (high temperature) and that require repeated peeling of the adherend. Ta.

On the other hand, acrylic double-sided adhesive sheets have high adhesive strength and are more heat resistant and durable than rubber adhesives, but
After all, it has a problem that it has stable creep strength and cohesive force over a wide range of temperatures, and is not necessarily sufficient for applications that require repeated peeling of adherends.

Furthermore, because silicone adhesives have excellent chemical resistance, solvent resistance, heat resistance, cold resistance, and durability, they are used as adhesive layers in double-sided adhesive sheets for special purposes. However, even in this case, it is unsuitable for applications that require stable creep strength and repeated peeling of adherends, and it has the drawbacks of being very expensive.

In addition, with these conventional double-sided adhesive sheets, if dust or debris on the adherend adheres to the adhesive layer, the adhesive strength and creep strength IW will decrease significantly, making it unusable and causing damage to the size. It was also impossible to reproduce and reuse the adhesive layer in such a state.

(Objective of the Invention) The present invention improves the drawbacks of these conventional double-sided adhesive sheets, has excellent adhesive strength and creep resistance, and is resistant to use when peeling and peeling of adherends. It is an object of the present invention to provide a double-sided adhesive sheet having an adhesive layer that can be recycled even when the adhesive layer is contaminated by dust.

In order to achieve this purpose, the present inventors conducted mt studies,
It has been newly discovered that a reaction product of a liquid diene polymer having at least two active hydrogen groups in the molecule and a polyisocyanate exhibits extremely excellent desired properties as an adhesive.

(Structure of the Invention) That is, the present invention uses a reaction product of a liquid diene polymer having at least two active hydrogen atoms in its molecule and a polyisocyanate as an adhesive, and uses a reaction product on at least one side of a base material. This is a double-sided pressure-sensitive adhesive sheet formed by laminating the pressure-sensitive adhesive layers.

In this case, the double-sided adhesive sheet of the present invention has an adhesive layer (
Hereinafter, it may also be referred to as the adhesive layer of the present invention. ) is laminated on at least one side of the base material, and even the adhesive layer of the present invention is laminated on both sides of the base material. Conventional adhesive layer ff: It may be a layered layer.

As the material used in the present invention, various synthetic resin films such as polyester film and polyethylene film, various woven fabrics, non-woven fabrics, etc. can be used. When a synthetic resin film with low adhesiveness to an adhesive is used as a base material, it is preferable to prime both the adhesive and the synthetic resin film with a substance having good adhesiveness.

For example, when a polyester film is used as a base material, the surface of the polyester film is preferably treated with polyethylene glycol terephthalate, polyisocyanate-modified polyester, polynisder polyurethane, or the like.

The liquid diene polymer used in the present invention exhibits fluidity at room temperature and has at least two active hydrogen groups in its molecule.Active hydrogen groups include hydroxyl, amino, imino, and carboxyl groups. , Merkagut Ichi, etc. More specifically, the liquid diene polymers include polybutadiene homopolymer, polyisoprene homopolymer, butadiene-styrene copolymer, phtadiene'-isoprene copolymer, butadiene-acrylonitrile copolymer, and phtadiene homopolymer having a number average molecular weight of 600 to 1000. Examples include -2-ethylhexyl acrylate copolymer and butadiene-n-octadecyl acrylate copolymer.

As the polyinsyanate used in the present invention, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, modified products thereof, recognized conductors, etc. can be used. Particularly preferred is a polyisocyanate having terminal incyanate groups obtained by reacting an i-type diene polymer with an excess of tolylene diisocyanate. Further, the proportion of free isocyanate in the polyisocyanate is preferably 3 to 10%.

In the present invention, in order to laminate a reaction product of a liquid diene polymer and a polyincyanate on a substrate, a liquid butadiene polymer, a metal catalyst and/or an amine catalyst, and a free incyanate group are replaced with methyl ethyl ketone oxime or the like. An organic solvent solution containing a masked isocyanate and additives such as an antioxidant and an ultraviolet absorber as necessary is applied onto the base material, and by heating this, the isocyanate of the polyisocyanate is regenerated and turned into a liquid. Advantageous is the method of reacting the diene polymer with the polyinsyanate.

(Effects) Since the double-sided pressure-sensitive adhesive sheet of the present invention is constructed as described above, it has a low adhesive force and can be easily peeled off from an adherend, but it also has a large supporting force for an adherend and has poor creep resistance. Because of its excellent properties, the attached items will not fall off and will be firmly supported.

In other words, let us take as an example the case where a printing press made of photosensitive resin is mounted on a printing machine using the double-sided adhesive sheet of the present invention, in which the adhesive layer of the present invention is laminated on one side and the conventional adhesive layer is laminated on the other side. Then, the double-sided sheet is mounted on a printing machine using the conventional adhesive layer side, and a letterpress printing plate is attached using the adhesive layer of the present invention on the front side, and the printing machine is rotated for a long time to print. Even when printing, there is no deviation of the letterpress at all. Furthermore, it has the advantage that the letterpress can be easily peeled off when replacing the letterpress, and another letterpress can be attached as is.

Furthermore, since the double-sided adhesive sheet of the present invention has low adhesion, there is little dust adhesion, and even if dust does adhere, it can be easily restored to its initial state by washing with water or gently wiping off the adhesive layer with alcohol, etc. , which can be used repeatedly over a long period of time.

The double-sided pressure-sensitive adhesive sheet of the present invention can be used as a dust removal tool, especially in precision machinery, by taking advantage of its small adhesive strength and reusable properties. For example, by wrapping the double-sided adhesive sheet of the present invention around a roll-shaped object or pasting it on a suitable jig, it can be used to remove dust from electronic precision parts that do not like dust, or to remove dust from records.

It can also be applied to dust removal mats used in clean rooms, etc. In these applications, if the dust removal effect deteriorates, it can be recycled by washing with water or the like.

(Example) The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples.

Actual Case 1 A primer having the following composition was applied onto a 100μ polyester film to a dry thickness of 25μ, and dried in an oven at 80°C to 130°C to form a single layer of primer on both sides.

Next, a pressure-sensitive adhesive composition having the following composition is applied onto one primer layer on one side of the film so that the thickness after curing is 100 μm.

The lt methyl ethyl ketone oxime addition type crosslinking agent is Po
1y bd R-45HT was reacted with excess tolylene diisocyanate to form free incyanate, and then reacted with methyl ethyl ketone oxime to remove the free isocyanate group f-T. 8 The obtained sheet was then heated at 140° C. for 5 minutes to react and cure to form an adhesive layer, and then a release paper was attached and rolled up.

Thereafter, an acrylic adhesive solution containing butyl acrylate as a main component was applied onto the uncoated polyester film surface on the back side of No. 5 and dried at 100 to 120°C to obtain a double-sided adhesive sheet.

Among the adhesive layers of this double-sided adhesive sheet, the adhesive layer made of the reaction product of the liquid diene polymer of the present invention and polyisocyanate has creep resistance (supporting force), adhesive strength (
Peel strength) and tackiness were measured in an atmosphere of 20°C and 60°C.

For comparison, NR adhesive and SIS adhesive 411. Acrylic adhesive and silicone adhesive were also measured. The results are shown in Table 1.

The measurement method is as follows.

Measurement of O-supporting capacity A pressure-sensitive adhesive sheet with a width of 25 cm and a length of 25 cm was pasted on a stainless steel plate, and while the stainless steel plate was held vertically, a load of 1~ was applied to the bottom of the pressure-sensitive adhesive sheet, and when it was left for 60 minutes, no shear occurred. Evaluate by measuring the length of the fall. The smaller the length of the slippage, the greater the support capacity.

Hold the 0-tackiness adhesive sheet at an angle of 10° to 30° with the horizontal,
A copper ball t l 00 mm with a diameter of V/32 to 3V32 inches is rolled onto the inclined surface, and the maximum diameter of the steel ball that stops on the adhesive surface is evaluated.

The larger the maximum diameter, the greater the tackiness. Note that when the angle is 10°, it is called A method, when the angle is 20°, it is called B method, and when the angle is 30°, it is called C method.

A 0-adhesive adhesive sheet is attached to a stainless steel plate, and the adhesive sheet is peeled 180° from one end. Peeling speed is 0.3m/mi
n, and the peel strength of 25 strips of paper is measured.

As can be seen from Table 1, the pressure-sensitive adhesive sheet with low tackiness and adhesive strength and high support strength is the only one of the present invention, and is found to have extremely excellent creep resistance.

4′! F a'F Dehara':] person Achilles Co., Ltd. (1 other person)

Claims (1)

[Claims] (1) In a double-sided adhesive sheet having adhesive layers on both sides of a base material, at least one side of the base material contains a liquid diene polymer having at least two active hydrogen groups in the molecule and a polyincyanate. A double-sided adhesive sheet made by laminating adhesive layers made of reaction products.