JP2003020454A - Adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive tape having adequate tackiness and re- releasability required when temporarily attached by a short-time heat press and strong adhesiveness to an adherend such as advertising displays required when mainly attached by a long-time heat press in order to solve problems in the adhesive tape used for fixation between an advertising display medium and a support. SOLUTION: This adhesive tape uses an acrylic tacky agent containing 100 pts.wt. copolymer composed of a (meth)acrylic acid alkyl ester, a (meth)acrylic acid and acrylonitrile and 2-50 pts.wt. copolymer composed of vinyl acetate and a vinyllactam and having a gel content.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive tape, and more specifically, it is preferably used for fixing a signboard medium such as a photographic film, a photographic paper, a poster and the like to a metal plate or the like serving as a support for the medium. Related to adhesive tapes.

[0002]

2. Description of the Related Art When using a sign or a printed matter such as letters or patterns photographed or copied on a photographic film or photographic paper as a sign, or a printed material such as a poster, a metal plate or the like serving as a support ( It is used by attaching it to an aluminum plate, etc.). As a method for this sticking process, a lamination method using a hot roll or a vacuum pressing method is usually used.
Regardless of which method is used, 1) a step of temporarily attaching the signboard display material such as the photographic film or photographic paper and the support (hereinafter referred to as a temporary attaching step), and 2) both of them for a long period of time. The step of firmly adhering so as to withstand the above exposure (hereinafter referred to as the main attaching step).

The physical properties required in the temporary sticking step are that the temporary sticking can be carried out without entrapment of air between the signboard display material such as a photographic film and the support, without wrinkles, and without entrapment of foreign matter such as dust. . Further, even if the temporary attachment fails, it is necessary to re-peel and perform the attachment again.
Especially when the display is large, this re-peeling performance becomes important.

Here, a specific example of a method of adhering the signboard display and the support will be described. First, double-sided adhesive tape is firmly attached to the back of the signboard display and laminated. Next, the signboard display with the adhesive tape and an aluminum plate as a support are temporarily attached. As a temporary sticking method, a hot pressing method which is less affected by curling is generally used. Then, after that, the main attachment is performed by hot pressing. When such a method is adopted, usually, the same equipment is often used for both the temporary attaching step and the main attaching step. Thus, if the equipment is the same,
The press temperature of the temporary sticking is the same as that of the main sticking, and the temporary sticking and the main sticking are used properly by changing the pressing time. For this reason, such a pressure-sensitive adhesive film can be subjected to a temporary sticking step by hot pressing for a short time, and can be peeled off neatly (removable) for easy position correction even after the temporary sticking. It is required to have a physical property of firmly adhering by hot pressing.

As a pressure-sensitive adhesive used for such a pressure-sensitive adhesive tape that requires removability, for example, a rubber-based heat-sensitive pressure-sensitive adhesive has been known. However, in this method, although strong adhesiveness can be exhibited, there is a problem that excessive adhesion and difficulty in re-peeling occur at a high temperature in the temporary adhesion step. Further, as a pressure-sensitive adhesive, for example, Japanese Patent Publication No. 63-2
No. 8114 discloses butyl acrylate and acrylic acid 2
-Acrylic ester-based polymer mainly composed of alkyl acrylate such as ethylhexyl, by blending a homopolymer of vinyl lactam such as 1-vinyl-2-pyrrolidone to improve the adhesive strength, A pressure-sensitive adhesive composition having water vapor permeability and hot melt coatability is disclosed. However, in the pressure-sensitive adhesive composition, since the acrylic ester polymer and the homopolymer of vinyl lactam have poor compatibility, they are easily separated from each other, and the adhesive strength, heat resistance, and other performances are improved. There was a problem that it could not be fully exerted.

[0006] Thus, it has a suitable tackiness, removability that can be immediately corrected even if there is a problem in the temporary application step, and heat-resistant pressability, and exhibits an adhesive strength that can withstand postings outdoors. It is difficult to say that satisfactory adhesive tapes have always been reported. .

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the adhesive tape used for fixing the above-mentioned signboard medium and the support, and, for example, provides an appropriate adhesiveness at the time of temporary attachment by hot pressing for a short time. An object of the present invention is to provide a pressure-sensitive adhesive tape having removability and strong adhesiveness to an adherend such as a signboard after the main application by hot pressing for a long time.

[0008]

The present invention according to claim 1 provides a copolymer 100 comprising (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile.
Provided is a pressure-sensitive adhesive tape which comprises an acrylic pressure-sensitive adhesive having a gel content and containing 2 to 50 parts by weight of a copolymer composed of vinyl acetate and vinyl lactam. The present invention according to claim 2 provides the adhesive tape according to claim 1, wherein the gel fraction of the acrylic pressure-sensitive adhesive is 20 to 60% by weight.

The present invention will be described in detail below.

In order to suitably use the adhesive tape of the present invention for the above-mentioned uses, the above-mentioned acrylic adhesive single layer is usually used.
It is laminated on a release paper that is peeled off at the time of use and commercialized as a rolled material. However, as will be described later in detail, a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is laminated on both surfaces of a core material may be used, and in some cases, it can be used as a single-sided pressure-sensitive adhesive tape. The adhesive tape of the present invention includes an adhesive film and an adhesive sheet.

The acrylic pressure-sensitive adhesive in the present invention is 100 parts by weight of a copolymer composed of (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile, and a copolymer 2 composed of vinyl acetate and vinyl lactam.
.About.50 parts by weight.

The (meth) acrylic acid alkyl ester in the present invention is not particularly limited as long as it is a polymerizable monomer capable of forming an adhesive polymer (glass transition temperature is preferably -50 ° C or lower). Examples include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. This is copolymerized with (meth) acrylic acid and acrylonitrile, which are polymerizable monomers capable of forming a polymer (glass transition temperature of 50 ° C. or higher) as a cohesive force component, to obtain a three-component copolymer. Here, the (meth) acrylic acid alkyl ester means an acrylic acid alkyl ester (meth) or an acrylic acid alkyl ester.

A copolymer composed of the above-mentioned (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile (hereinafter sometimes referred to as a three-component copolymer)
By copolymerizing the three components, a copolymer having both initial tackiness and adhesive strength over time can be obtained.

The weight average molecular weight (M
When w) is too low, cohesiveness is excellent but cohesive force is insufficient, and when it is too high, cohesive force is excellent but adhesive force is insufficient.

The copolymer of vinyl acetate and vinyl lactam in the present invention (hereinafter referred to as vinyl acetate-vinyl lactam copolymer) has a vinyl lactam content of
It is preferably 20 to 80 mol%. The glass transition temperature of the copolymer obtained at this time is 50 to 90 ° C.
Is preferred.

Examples of the vinyllactam of the present invention include 1-vinyl-2-pyrrolidone, 1-vinyl-5-methyl-2-pyrrolidone, 1-vinyl-2-piperidone,
N-vinyl-ε-caprolactam may be mentioned, and among these, 1-vinyl-2-pyrrolidone is preferably used.

If the weight average molecular weight (Mw) of the vinyl acetate-vinyl lactam copolymer is too low, the tackiness is excellent but the cohesive force is insufficient, and if it is too high, the cohesive force is excellent but the tackiness is insufficient. Will be done.

The blending ratio of the three-component copolymer and the vinyl acetate-vinyl lactam copolymer in the present invention in the copolymer composition is 100 parts by weight of the above three-component copolymer.
The amount of the vinyl acetate-vinyl lactam copolymer is 2 to 50 parts by weight, preferably 3 to 30 parts by weight. When the blending amount is less than 2 parts by weight, the glass transition temperature of the resulting acrylic pressure-sensitive adhesive increases, tack on the adherend is lost, and the performance of the pressure-sensitive adhesive film deteriorates. On the other hand, when the amount is more than 50 parts by weight, the glass transition temperature of the obtained acrylic pressure-sensitive adhesive is lowered, tackiness to an adherend is increased, and removability is lowered.

The acrylic pressure-sensitive adhesive in the present invention is a gel component based on a crosslinking reaction by adding a cross-linking agent after or at the time of blending the above-mentioned three-component copolymer and vinyl acetate-vinyl lactam copolymer. Need to be generated. The formation of the gel component due to the formation of such a cross-linked structure makes it possible to develop a good balance between removability, tackiness and adhesiveness.

The amount of the isocyanate-based crosslinking agent added is not particularly limited as long as the gel fraction, which is a measure of the crosslinked structure of the obtained pressure-sensitive adhesive, is 20 to 60% by weight, and is preferably used. The amount is 0.3 to 8 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the above three-component copolymer.

The preferred gel fraction after crosslinking of the acrylic pressure-sensitive adhesive in the present invention is 20 to 60% by weight, and more preferably 30 to 50% by weight. Gel fraction is 2
If it is less than 0% by weight, the removability may decrease.
When the gel fraction is more than 60% by weight, the tack on the adherend becomes small and the adhesion performance may deteriorate. The gel fraction referred to here is the proportion of the solvent-insoluble portion of the acrylic pressure-sensitive adhesive after the crosslinking reaction.

The cross-linking agent used in the present invention is not particularly limited as long as it can be cross-linked so as to have a gel fraction in the above range, and examples thereof include an epoxy-based cross-linking agent, an isocyanate-based cross-linking agent, and an aziridine-based cross-linking agent. Agents, metal chelate-based cross-linking agents and the like that can chemically react can be used.
Among these, isocyanate type crosslinking agents are preferably used.

The acrylic pressure-sensitive adhesive thus obtained may be used as a single-layer pressure-sensitive adhesive tape (so-called non-support type) by laminating it on a release paper as a pressure-sensitive adhesive layer. You may stack and use. Means for providing an acrylic pressure-sensitive adhesive as a pressure-sensitive adhesive layer on release paper or a core material is not particularly limited, for example, the copolymer composition is a solution of toluene, xylene, ethyl acetate, etc., A coating method of coating and drying using a coating machine such as a knife coater, comma coater, or roll coater may be adopted. Further, this pressure-sensitive adhesive layer may be laminated and stored with a release paper which has been subjected to a release treatment on one side in a sandwiched form,
Alternatively, an adhesive layer may be provided on one surface of a release paper that has been subjected to a double-sided release treatment, and the release paper may be rolled and stored. The thickness of the pressure-sensitive adhesive layer is appropriately set depending on the purpose of use of the product and the property of the adherend, but it is generally preferable that the thickness is about 10 to 70 μm.

The release paper or the release treatment method of the present invention is not particularly limited, and a commonly used one may be used. The core material is not particularly limited, and examples thereof include a polyethylene terephthalate film, a polyethylene film, a plasticized vinyl chloride resin film, and a polycarbonate film. The thickness of the synthetic resin film is not particularly limited, but generally 10 to 1
Those having a diameter of about 00 μm are used.

The pressure-sensitive adhesive tape of the present invention contains, for example, a tackifier, a coupling agent, a filler, a filler, a softener, a plasticizer, an interface, if necessary, as long as the object of the present invention is not hindered. Activator, antioxidant, heat stabilizer, light stabilizer,
You may add various additives, such as an ultraviolet absorber and a coloring agent.

(Function) Since the pressure-sensitive adhesive tape of the present invention uses an acrylic pressure-sensitive adhesive which is composed of the above-mentioned specific copolymer composition and has a gel fraction, it is produced by hot pressing.
Appropriate tackiness and removability at the time of temporary application are exhibited, excellent workability is maintained, and strong adhesion is exhibited after the main application, and it can withstand long-term outdoor use. Further, even at room temperature, it is possible to exhibit appropriate tackiness and removability under pressure. In other words, the acrylic pressure-sensitive adhesive in the present invention also has a property as a pressure-sensitive heat-sensitive adhesive.

[0027]

[Examples] By showing Examples and Comparative Examples below,
The present invention will be specifically described. The present invention is not limited to the following examples.

(Example 1) [Preparation of acrylic pressure-sensitive adhesive] 1) Butyl acrylate-methacrylic acid-acrylonitrile copolymer butyl acrylate 85 mol%, methacrylic acid 3 mol%,
Acrylonitrile was copolymerized at a ratio of 12 mol% to prepare an ethyl acetate solution of a butyl acrylate-methacrylic acid-acrylonitrile copolymer having a solid content of 20% by weight.

2) Vinyl acetate-1-vinyl-2-pyrrolidone copolymer 70 mol% vinyl acetate, 1-vinyl-2-pyrrolidone 3
Copolymerization was carried out at a ratio of 0 mol% to prepare an ethyl alcohol solution of a vinyl acetate-1-vinyl-2-pyrrolidone copolymer having a solid content of 50% by weight.

The above butyl acrylate-methacrylic acid-acrylonitrile copolymer ethyl acetate solution and vinyl acetate-1-vinyl-2-pyrrolidone copolymer ethyl alcohol solution were uniformly mixed at a solid content ratio of 100: 3 (weight ratio). An acrylic adhesive solution was prepared by mixing.

[Preparation of Adhesive Tape] To the above acrylic adhesive solution, 10 parts of an isocyanate crosslinking agent (Coronate L-55E; manufactured by Nippon Polyurethane Co., Ltd.) was added to butyl acrylate-methacrylic acid-acrylonitrile copolymer.
After adding at a ratio of 0: 2 (weight ratio) and stirring sufficiently,
The release paper made of polyethylene terephthalate (PET) was coated on the surface and dried to prepare an adhesive tape having an adhesive layer thickness of 20 μm. [Preparation of sample for evaluation] The pressure-sensitive adhesive tape obtained by the above method was attached to the back surface of a color photographic paper (A4 size) with a heat press machine at 120 ° C. and a pressure of 1.96 kN / cm ^{2 for} 100 seconds. A sample for evaluation was prepared.

(Examples 2 to 5, Comparative Examples 1 to 4) Example 1
And the mixing ratio of the ethyl acetate solution of the butyl acrylate-methacrylic acid-acrylonitrile copolymer of the acrylic adhesive and the vinyl acetate-1-vinyl-2-pyrrolidone copolymer ethyl alcohol solution, and Coronate L
An adhesive tape was produced in the same manner as in Example 1 except that the addition amount of -55E was changed to the ratio and the addition amount shown in Table 1, respectively. In addition, the 1) component described in Table 1 is the butyl acrylate-methacrylic acid-acrylonitrile copolymer described in Example 1, and the 2) component is the vinyl acetate-1-vinyl-2-pyrrolidone described in Example 1. A copolymer is shown.

[Evaluation Method] <Gel Fraction> As shown in the above [Preparation of adhesive tape],
A cross-linking agent-added acrylic pressure-sensitive adhesive solution was applied onto a PET film, and a cross-linking reaction was carried out at 40 ° C. for 72 hours. Using this as a sample, the dry weight (Wa) after immersion in ethyl acetate at 40 ° C. for 24 hours was measured, and the weight before immersion (Wb)
The value calculated by the following equation (1) was compared to the gel fraction. Gel fraction (% by weight) = (Wa / Wb) × 100 (1) <Performance evaluation> 1) Workability during temporary attachment of the adhesive tapes obtained in the above Examples and Comparative Examples, 2) During temporary attachment Removability, 3) Adhesive strength after this sticking was observed and measured by the method described below to evaluate its performance. The evaluation results are shown in Table 1.

1) Workability at the time of temporary sticking The release paper on one side of the evaluation sample prepared above was peeled off,
It was attached to an aluminum plate having a thickness of 2 mm and temporarily attached by a heat press machine. (Temporary attachment conditions: temperature 120 ° C, pressure 1.96k
After the pressing pressure was released at N / cm ^{2 for} 30 seconds, it was visually evaluated whether or not the attached evaluation sample was completely temporarily attached to the end. The evaluation standard was evaluated in the following two stages. ○ (Good): The tape is temporarily attached without peeling to the edges. Poor (poor): Floating and peeling were observed at the edges, and temporary attachment was not possible. 2) Removability during temporary attachment Peel off the release paper on one side of the evaluation sample prepared above,
It was attached to an aluminum plate having a thickness of 2 mm and temporarily attached by a heat press machine. (Temporary attachment conditions: temperature 120 ° C, pressure 1.96k
30 seconds after releasing the pressing pressure at N / cm ^{2 for} 30 seconds
After a lapse of seconds, the evaluation sample was peeled again from the aluminum plate, and the peeled state was evaluated. The evaluation standard was evaluated in the following two stages. ○ (Good): Can be used repeatedly without damaging the photographic paper × (Poor): High peeling force is required at the time of re-peeling, so the photographic paper is damaged due to tears, etc. and cannot be used repeatedly

3) Adhesive strength after final sticking The sample temporarily stuck in 1) above was finally stuck by a hot press machine. (Conditions for sticking: temperature 120 ° C, pressure 1.96k
N / cm ^{2 for} 200 seconds) Pressed sample at room temperature for 2
After leaving it for 4 hours, it was cut into a size of 25 mm × 300 mm and subjected to a 180 ° peeling test (test condition: 23 ° C × 65% R
H, pulling speed 300 mm / min) to measure the adhesive strength.

[0036]

[Table 1]

[0037]

The pressure-sensitive adhesive tape of the present invention comprises 100 parts by weight of a copolymer of (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile, and 2 to 50 of a copolymer of vinyl acetate and vinyl lactam. Since it uses an acrylic pressure-sensitive adhesive that contains parts by weight and has a gel content, it has appropriate adhesiveness and removability during temporary attachment, and the adhesion of signboards etc. after this attachment. A strong adhesiveness to the body can be expressed in a well-balanced manner. Therefore,
By using the adhesive tape of the present invention, it is possible to perform temporary attachment and final attachment of a signboard medium such as a photographic film, a photographic paper, a poster, etc. and a support with a single press machine, thereby improving productivity in signboard production. Can be greatly improved.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09J 139/04 C09J 139/04

Claims (2)

[Claims] 1. A (meth) acrylic acid alkyl ester,
An acrylic adhesive containing 100 parts by weight of a copolymer composed of (meth) acrylic acid and acrylonitrile and 2 to 50 parts by weight of a copolymer composed of vinyl acetate and vinyl lactam and having a gel content is used. An adhesive tape characterized by being. 2. The gel fraction of the acrylic pressure-sensitive adhesive is 20 to 6
The adhesive tape according to claim 1, wherein the adhesive tape is 0% by weight.