JPH02178377A - Production of repeatedly peelable tacky sheet - Google Patents

Abstract

PURPOSE:To obtain the subject sheet having excellent repeating peelability by covering a separator having low peeling resistance with a microspherical tacky agent, lapping a separator having high peeling resistance, drawing through nip rolls, peeling the former and laminating a surface substrate on the surface of the tacky agent. CONSTITUTION:At first, a separator having low peeling resistance is covered with a microspherical tacky agent and dried. Next, a separator having higher peeling resistance than the former is lapped on the former and drawing through nip rolls, then the separator having low peeling resistance is peeled off, thus a surface substrate on the surface of the tacky agent layer to afford the aimed sheet. Besides, back face of the surface substrate and/or the surface of the tacky agent before laminating is subjected to corona discharge treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a pressure-sensitive adhesive sheet, and particularly to an improvement in a method for producing a removable pressure-sensitive adhesive sheet using a microspherical pressure-sensitive adhesive.

[Prior art and its problems]

In recent years, with the development of the information society, adhesive sheets have been widely used for labels, stickers, stickers, patches, delivery slips, etc. in a wide range of fields such as commercial, industrial, and household use.

The adhesive sheet is a permanent adhesive type that is used permanently after being applied to the product, etc., and it remains attached to the adherend for a long time.
There is also a re-peelable type that is peeled off and discarded. The latter type is generally called a removable pressure-sensitive adhesive sheet. By the way, conventional removable pressure-sensitive adhesive sheets have generally used two-component (adhesive component and curing agent) solvent-based pressure-sensitive adhesives or emulsion-based pressure-sensitive adhesives. Recently, microspherical adhesive (particle size, approximately 1 to 300μ)
Regarding tapes or sheets having an adhesive layer, adhesive tapes or sheets have been developed that do not easily deteriorate in adhesive strength and removability even after repeated application and peeling to the surfaces of various adherends. There is. (Special Public Interest Publication 58-18
No. 959, JP-A-50-2736, JP-A-Sho (i2-2
63273, etc.) JP-A No. 50-2736 describes a structure in which a part of a microsphere adhesive is bonded to a base material using a binder so as to be exposed on the surface. The reason why the adhesive exhibits the ability to repeatedly attach and peel is explained that it is because the physical socket effect effectively prevents the transfer of the adhesive to the adherend. Adhesion and
In order to exhibit the ability to repeatedly peel off, a part of the microspherical adhesive must be exposed on the surface of the adhesive layer, that is, the side that contacts the adherend, and the other part must be firmly bonded to the support. It is necessary that the structure is

In order to form an adhesive layer with such a structure, a conventional method for manufacturing an adhesive sheet, that is,
It is not possible to adopt a method in which a microsphere adhesive is first applied to a separator and a surface base material is laminated thereon. The reason for this is that in the conventional method, exposed portions of the microsphere adhesive do not appear on the surface of the adhesive layer after it has been transferred to the surface substrate, and removability characteristics cannot be developed.

For this reason, a method of directly applying the adhesive to the surface substrate (in this case, the exposed part of the microspherical adhesive will easily appear on the surface of the coating layer) may be considered, but this method does not improve the quality of the surface substrate. There is a problem that the amount decreases. In other words, the method of applying the adhesive to the surface base material requires a drying process and a humidity conditioning process (if the humidity is not controlled, there will be a difference in elongation between the surface base material and the separator, and when they are bonded together, air will be trapped in the area. This is because they are affected by heat and moisture (which may cause bulges and result in defective products). In particular, when the surface substrate is a heat-sensitive recording material, color develops during drying. In addition, when the surface base material is high-grade coated paper for printing (coated paper, art paper, cast coated paper), etc., there is a problem that the gloss is extremely reduced due to the influence of moisture during humidity control. Therefore, in reality, it is impossible to employ such a manufacturing method.

[Problem to be solved by the invention]

The present invention has excellent initial adhesion, tackiness, and removability without deteriorating the quality of the surface base material when configuring a pressure-sensitive adhesive sheet using a microspherical pressure-sensitive adhesive. An object of the present invention is to provide a method for producing an excellent pressure-sensitive adhesive sheet that does not deteriorate even after repeated steps.

[Means to solve the problem]

In a method for producing an adhesive sheet using a microspherical adhesive, the adhesive is first coated on a separator with a light release and dried, and then a separator with a heavy release is placed on top of this and applied to a nip roll, and then the adhesive is peeled off. This is a method for producing a releasable pressure-sensitive adhesive sheet, which is characterized by peeling off a light separator and bonding a surface base material to the surface of the pressure-sensitive adhesive layer.

[Effect]

As configured above, the present invention uses two types of separators with different peeling forces to transfer the microsphere adhesive layer from a separator with a light release force to a separator with a heavy release force, and then peels off the separator with a light release force. , which is characterized by newly bonding a surface base material, and by doing so, a part of the microspheres can be exposed on the surface of the microsphere adhesive layer without degrading the quality of the surface base material. A pressure-sensitive adhesive sheet with excellent initial adhesion and removability can be obtained even after repeated adhesion and peeling to various adherends.

To explain the present invention in more detail, the microspheric adhesive used in the present invention includes ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, The main component is methacrylic acid ester such as nonyl acrylate, nonyl acrylate, lauryl acrylate, methyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, lauryl methacrylate, etc., and these monomers and acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, N-methylol (meth)acrylamide, (meth)acrylamide, glycidyl methacrylate, acrylic glycidyl Ether, vinyl acetate, styrene, acrylonitrile, trimethylamine methacrylamide, trimethyl 7mine-p
-vinylhenzimide, ammonium acrylate, sodium acrylate, N,N-dimethyl-N-(β-
Methacryloxyethyl) ammonium propionate betaine, ■, 1-dimethyl-1-(2-hydroxypropyl)amine methacrylimide, 4,4.9-trimethyl-4-azonia-7-oxy-9-decene-1-sulfonate , 1,1-dimethyl-1-(2,3-dihydroxypropyl)amine, methacrylimide, and other monomers.

In addition, regarding a specific manufacturing method, it can be manufactured, for example, by the suspension polymerization method described in Japanese Patent Publication Nos. 50-2736 and 61-148278.

Next, the spherical adhesive is coated on the separator with a light peeling force by using a normal coating device such as a water dispersion coating liquid containing the spherical adhesive with a binder and other auxiliaries as necessary. , air knife coater, roll coater, gravure coke, screen printing, etc.

In this case, the coating amount is suitably 7 to 30 g/m' in terms of dry weight, preferably 10 to 25 g/rrr.

Incidentally, if it is less than 7 g/m, the adhesive effect is poor, and if it is 30 g/g or more, it is not necessary from the economic point of view.

The separator used in the present invention is glassine paper or pigment-coated paper coated with a release agent, or polylaminated paper made by laminating polyethylene, etc. onto kraft paper or high-quality paper, etc., coated with a release agent. .

As for the release agent, it is easy to use a release silicone composition. Regarding silicones used in paper, (11) condensation type that forms a release film through a polycondensation reaction of organopolysiloxane using an organic acid metal salt catalyst such as an organotin compound; (2) silicone containing platinum or a platinum compound; As a catalyst, an addition type (
3) Special publication of cross-linkable materials by electron beam irradiation
669 and Japanese Patent Publication No. 59-64670, etc., an electron beam cure type that forms a releasable film using an organopolysiloxane; (4) a type that can be cured by ultraviolet irradiation;
A diorganopolysiloxane having an epoxy functional group disclosed in Japanese Patent Publication No. 60-47064.

etc.

The factors that affect the peeling force (peeling weight) are ■molecular weight,
These include: - crosslinking density (number of crosslinking points per unit of substance), - curing conditions, - multifunctional composition, - film thickness, and - exposure to light, humidity, and heat. Usually, the control of peeling force is
,■ is often done by adjusting.

One of the features of the present invention is that it uses a separator with a light peeling force and a separator with a heavy peeling force, but the difference in the peeling force between the two separators is relative;
In order to improve the transferability of the adhesive, it is desirable that the difference be as large as possible, regardless of the peeling speed. Specifically, ff1
lJ The difference in peeling force between a separator with a heavy female blade and a separator with a light peeling force is preferably at least 25 g or more than 150 mm when measured at a peeling speed of 0.3 m/min. Incidentally, the peeling force in this case is 0.
When measured at a peeling speed of 3 m/min, 5-25g15011. on a separator with a light peeling force. A separator with a heavy peeling force of 30 to 60 g150 cm is desirable. In addition, at a peeling speed of 50 m/min, a separator with a light peeling force weighs 30 to 100 g,
Separator with heavy release force: 60-200 g/50
It is desirable that the fJ1 release force female blade be approximately as. (Peeling force here means that after pasting Knit-31B tape onto a separator and creating a sample with a width of 50m5,
The tape is rotated 180° from the separator at a constant speed.
It is defined as the load (g150tm) applied when ff111 is pulled at a pulling angle of . ) The release agent can be applied to the separator base paper using a gravure coater, a bar coater, etc. In this case, the coating amount (2) is 0.3 to 1.5 g/% by dry weight, preferably 0. .5 to 1.2 g/r+ (is appropriate.

0.3g/n? If it is less than 1.5 g/m, there will be large variations in peeling performance, and if it is more than 1.5 g/m, it is not necessary from the economic point of view.

In the present invention, the adhesive force between the front substrate and the adhesive can be further increased by subjecting the back surface of the front substrate and/or the surface of the adhesive layer to corona discharge treatment before bonding. As a result, better re-peelability can be obtained when a separator (separator with heavy peeling force) is peeled off. Incidentally, the conditions for corona discharge treatment are such that the wetting coefficient of additive-free polyethylene film is 34 dyne/cm.
It is desirable to process so that s is preferably 40 dyne/(o+ or more).

In the present invention, epoxy resins (resin-like substances having two or more epoxy groups in one molecule) and isocyanate resins (for example, isocyanate, hexamethylene diisocyanate, tolylene diisocyanate, etc.) are used as crosslinking agents in the microsphere adhesive layer. ) can further improve the re-peelability with respect to adhesion and peeling to adherends. The amount of the crosslinking agent added is preferably 0.5 to 30 parts, preferably 1 to 10 parts, based on 100 parts of the solid content of the microsphere adhesive. Incidentally, if it is less than 0.5 parts, the effect will be poor, and if it is more than 30 parts, the viscosity of the adhesive coating solution will increase significantly, causing problems in pot life.

The present invention will be specifically explained below with reference to Examples, but it is of course not limited thereto.

Further, unless otherwise specified, parts and percentages in the layers indicate parts by weight and percentages by weight, respectively.

Example 1 Dry 10.8 g/- of addition type silicone liquid of the following formulations A and B was applied to the surface of glassine paper weighing 85 g/n.
After coating with a bar coater so that

CA) Light Separate Lake - Shin-Etsu Silicone KS-857 100 parts Catalyst PL-81
part toluene 399 parts CB3 heavy separator East Shinrinrifun BY24-312 100
Part catalyst 5RX212 0.6 parts Toluene 399.4 parts The heat curing conditions were 140° C. for 60 seconds.

First, on the surface of the light separator (A) above, apply an acrylic emulsion type microsphere adhesive (manufactured by Toyo Ink Manufacturing Sumikiku, trade name: Olivine BPW-4960-IKJ) to a dry weight of 13 g/m. Then, roll coater
After coating, it was dried at 120°C for 90 seconds. After conditioning the humidity on the back side, the heavy separator side of CB) was pasted to the glue side, and passed through two rolls to be crimped. Next, after peeling off the light separator in (A), the back side of cast coated paper (manufactured by Kanzaki Paper Co., Ltd., trade name [Mirrorco] J85g/) was pasted to the surface of the lake, passed through nip rolls to be crimped, and then re-attached. A ff1ll release adhesive sheet was obtained.

The removability of the adhesive sheet thus obtained was as shown in the attached table.

Example 2 An acrylic emulsion microsphere adhesive (Toyo Ink Manufacturer al.
Coated with Olivine BPW-4960-IKJ (product name: 13 g/n?) using a roll coater. After drying, the heavy separator side of CB) was bonded to the glue side and passed through a nip roll. Next, after peeling off the light separator (A), thermal paper (manufactured by Kanzaki Paper ■,
(trade name: rK PT-86NJ '19 g/nf)'' was bonded to the back surface, and passed through nip rolls to be press-bonded to obtain a removable pressure-sensitive adhesive sheet. The removability of the adhesive sheet thus obtained was as shown in the attached table.

Example 3 On the surface of the same light separator (A) as in Example 1, a pressure-sensitive adhesive having the following composition was coated at a concentration of 13 g/m and dried.

100 parts of acrylic emulsion microsphere adhesive (manufactured by Toyo Ink Manufacturing Co., Ltd., product name: Olivine BPW-4960-
IKJ); After conditioning the back side of the epoxy resin curing agent (FX-931, manufactured by Nippon Carbide Kogyo ■), the heavy separator (B) was attached in the same manner as in Example I, and it was crimped with nip rolls as usual. . next(
A] After peeling off the light separator, cast coat G (manufactured by Kanzaki Paper Co., Ltd., product name "Mirror Coat J85g/
The back side of the sheet was bonded to the surface of the lake and pressed with nip rolls to obtain a removable pressure-sensitive adhesive sheet. The removability of the adhesive sheet thus obtained was as shown in the attached table.

Example 4 The same materials as in Example 1 are used, but in the process, adhesive is applied to the light separator [A]. After drying: the heavy separator (B) is pasted together, and then the light separator [A] is peeled off. After this, the adhesive surface was heated to an oscillation frequency of 30
Corona treatment was performed at KHz, output voltage 34 KV, output 0.7 KW, and processing speed 4 m/min. After that, Ki→・Stock Coat @ (manufactured by Kanzaki Seigi ■, product name “Mirror Coat J85g”)
/m) was attached to the surface of the lake, and the pressure was applied to the surface using a nip roll as usual to obtain a releasable pressure-sensitive adhesive sheet. The removability of the adhesive sheet thus obtained was as shown in the attached table.

Comparative Example 1 An acrylic emulsion microsphere adhesive (Toyo Ink Preparation G
Manufactured by 21, product name: Olivine BPW-4960-IKJ
) to 13 g/% using a roll coater.After drying, the back side of Cath 1-coated paper (manufactured by Kanzaki Paper 0 Kiku, trade name: "Mirrorco N85g/E") was bonded to the adhesive side, and the paper was coated with a nip roll. A removable pressure-sensitive adhesive sheet was obtained.

The removability of the adhesive sheet thus obtained was as shown in the attached table.

Comparative Example 2 An acrylic emulsion microsphere adhesive (manufactured by Toyo Ink Manufacturing Co., Ltd., product name "Olivine BPW-4960-IKJ") was applied on the back side of mirror coated paper (manufactured by Kanzaki Paper Co. Ltd., trade name "Miracoat J85 g/m"). so that it becomes 13 g/m,
It was coated with a roll coater and dried. Next, after controlling the humidity from the surface by steam damping, it was laminated with the same heavy separator CB as in Example 1, and pressed with nip rolls to obtain a releasable pressure-sensitive adhesive sheet. The removability of the adhesive sheet thus obtained was as shown in the attached table.

Comparative Example 3 An acrylic emulsion microsphere adhesive (manufactured by Toyo Ink) was applied to the surface of a heavy separator made of the same CB as in Example 1.
Coated with 13 g/rd of Olivine BPW-4960-IKJ (trade name) by a roll coater and dried, then coated with thermal paper (manufactured by Kanzaki Paper Industries, trade name: rKPT-86N).
J79g/r4) and pressed together using a nip roll as usual to obtain a releasable pressure-sensitive adhesive sheet. The removability of the adhesive sheet thus obtained was as shown in the attached table.

Comparative Example 4 Thermal paper (manufactured by Kanzaki Paper Co., Ltd., product name rKPT-86NJ7
9g/m) on the back side of an acrylic emulsion microsphere adhesive (manufactured by Toyo Ink Mfg., trade name: Olivine BPW-
4960-IKJ) was coated with a roll coater at a concentration of 13 g/m' and dried.

Next, after controlling the humidity from the surface by steam damping, it was laminated with a light separator of CB (the same as in Example 1) and pressed with a nip roll as usual to obtain a removable pressure-sensitive adhesive sheet. The removability of the adhesive sheet thus obtained was as shown in the attached table.

(Measurement of re-peelability) Separate strips were removed from each of the 21 KJLF adhesive sheets prepared in Examples and Comparative Examples, the adhesive sheet pieces were pasted on the surface of art paper, and the adhesive sheets were rolled for 50 minutes using a 2 kg roller.
I crimped it by going back and forth. After 2 hours and 3 days, the adhesive sheet piece was pulled from the art paper and ff11 was removed, and then the same operation of adhering to and peeling from the art paper was repeated 20 times.

(Appended Table) By combining them, it became possible to expose the microsphere surface to the adherend surface side. As a result, even if high-grade coated paper or thermal paper, which cannot be bonded directly, is used as a surface substrate, no adhesive remains on the adherend even after repeated bonding and peeling. A suitable removable pressure-sensitive adhesive sheet can be obtained.

Claims (3)

[Claims] (1) In a method for producing a removable adhesive sheet using a microspherical adhesive, the adhesive is first coated and dried on a separator with a light peeling force, and then a separator with a heavier peeling force than the separator is layered on top of this. A method for producing a removable pressure-sensitive adhesive sheet, which comprises removing a separator with a light peeling force after passing through a nip roll, and bonding a surface base material to the surface of the pressure-sensitive adhesive layer. (2) The method for producing a removable pressure-sensitive adhesive sheet according to claim 1, characterized in that the back surface of the front substrate and/or the surface of the pressure-sensitive adhesive layer is subjected to a corona discharge treatment before bonding. (3) The method for producing a removable pressure-sensitive adhesive sheet according to claim 1, characterized in that an epoxy resin or a polyisocyanate resin is added to the pressure-sensitive adhesive layer.