JP3361589B2 - Adhesive sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel pressure-sensitive adhesive sheet, and more particularly to a pressure-sensitive adhesive sheet having excellent adhesiveness to a metal surface to which oil is attached even if the oil is not removed.

[0002]

2. Description of the Related Art Rust-prone metals such as iron, copper and brass are usually coated with rust preventive oil on the surface to prevent oxidation by oxidizing substances in the atmosphere such as oxygen during storage before processing. The surface of metal used industrially is often contaminated with mechanical oil or the like. Conventionally, in order to attach an adhesive sheet to such metals for the purpose of management and display, it has been necessary to remove the rust-preventing oil or machine oil applied to the metal surface to clean the metal surface.
However, particularly when the rust preventive oil applied to the metal surface is removed for the purpose of preventing rust, the rust preventive action is impaired, and rust is induced by an oxidizing substance in the air, which is not preferable. Further, it takes a lot of labor to remove the oil on the metal surface for sticking the pressure-sensitive adhesive sheet, and there is a problem that productivity is unavoidably reduced. Therefore, it has been desired to develop a pressure-sensitive adhesive sheet that can be attached for the purpose of management and display without removing the rust-preventing oil or machine oil attached to the metal surface.

[0003]

SUMMARY OF THE INVENTION In response to such a demand, the present invention has an oil surface adhesiveness that can be applied without removing rust-preventive oil applied to a metal surface or attached mechanical oil. The purpose of the present invention is to provide an excellent pressure-sensitive adhesive sheet.

[0004]

Means for Solving the Problems As a result of intensive studies to develop a pressure-sensitive adhesive sheet having the above-mentioned preferable properties, the present inventors have identified a powdery filler and a fibrous filler on an oil-absorbent sheet. By providing the pressure-sensitive adhesive layer contained in a proportion, the oil content present at the adhesive interface with the metal surface passes through the pressure-sensitive adhesive layer and is effectively absorbed by the oil-absorbent sheet. It has been found that excellent adhesive strength can be exhibited without removing it, and the present invention has been completed based on this finding. That is, the present invention, on the oil-absorbent sheet, a powdery filler having an average particle size smaller than the thickness of the pressure-sensitive adhesive layer and / or a fibrous filler having an average diameter smaller than the thickness of the pressure-sensitive adhesive layer, relative to the pressure-sensitive adhesive solid content. To provide a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing 2 to 40% by weight.

The present invention will be described in detail below. As the oil-absorbent sheet used for the pressure-sensitive adhesive sheet of the present invention, one that efficiently absorbs various oil components present on the metal surface is used. The oil components present on the metal surface include mineral oils such as machine oils applied for the purpose of rust prevention, animal and vegetable oils and rust preventive oils, and cutting oils attached during cutting and polishing. The cutting oil includes mineral oils and animal and vegetable oils that are water-insoluble cutting oils, and water-soluble cutting oils obtained by solubilizing these mineral oils and animal and vegetable oils with an emulsifier, a rust inhibitor and the like. Even if the water-soluble cutting oil is an oil, it is emulsified, so that it is hydrophilic and exhibits different characteristics from other oils. That is,
The oil components present on the metal surface can be roughly classified into non-hydrophilic oils and hydrophilic oils, and the oil-absorbent sheet must be able to efficiently absorb these oil components. As such an oil-absorbing sheet, for example, paper without using a sizing agent, non-woven fabric using synthetic fibers or natural fibers, a sheet laminated with a water-absorbing polymer or an oil-absorbing polymer, and the like can be used. The thickness of the oil-absorbent sheet is not particularly limited, but is usually about 30 to 100 μm.

In the pressure-sensitive adhesive sheet of the present invention, as the oil-absorbent sheet, if desired, the surface opposite to the pressure-sensitive adhesive layer side can be prevented from absorbing oil and water, have higher mechanical strength, or can be printed. For the purpose of labeling, a laminate of polymer base materials can be used. Examples of the polymer base material include polyester sheets such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, sheets made of synthetic resin such as polyvinyl chloride, and cellulosic sheets. The method of laminating the polymer base material and the oil-absorbent sheet is not particularly limited, but a method of laminating using an adhesive or an adhesive is usually used. In the pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive layer containing a filler is provided on the oil-absorbent sheet. There are no particular restrictions on the type of adhesive used in this adhesive layer,
Conventionally used pressure-sensitive adhesive sheets applied to metals, for example, acrylic or rubber solvent type, emulsion type, etc. can be used, but when hydrophilic oil such as water-soluble cutting oil is targeted. The emulsion type is not preferable in terms of water resistance.

On the other hand, as the filler to be contained in the pressure-sensitive adhesive layer, powdery filler and / or fibrous filler are used. As the powdery filler, both inorganic and organic can be used. Examples of the powdery inorganic filler include clay, talc, mica, kaolin, zeolite, calcium silicate, montmorillonite, silicates such as bentonite, silica, diatomaceous earth, barium ferrite, barium oxide, oxides such as pumice, and water. Aluminum oxide, magnesium hydroxide, hydroxides such as basic magnesium carbonate, carbonates such as calcium carbonate, magnesium carbonate, dolomite and dawsonite, and sulfates or sulfites such as calcium sulfate, barium sulfate and calcium sulfite. . Examples of the powdery organic filler include wood particles such as wood powder and cotton powder, fir shell powder, crosslinked rubber powder, and plastic powder. When targeting hydrophilic oils such as water-soluble cutting oils, among these powdery fillers, for example, silicates such as clay and talc, hydroxides such as aluminum hydroxide and magnesium hydroxide, etc. A hydrophilic one is preferable, and a silicate such as clay or talc is particularly preferable. In the present invention, the average particle diameter of the powdery filler needs to be smaller than the thickness of the pressure-sensitive adhesive layer. When the average particle size is equal to or larger than the thickness of the pressure-sensitive adhesive layer, the adhesiveness to the metal surface is reduced. Further, as the fibrous filler, both inorganic and organic can be used. As the fibrous inorganic filler, for example, glass fiber, carbon fiber, aluminum fiber, stainless fiber, copper fiber, nickel fiber, silicon carbide fiber, single crystal potassium titanate,
Fibers such as fibrous calcium carbonate, whiskers corresponding thereto, needle-like ones such as wollastonite, magnesium oxysulfate and the like can be mentioned. Examples of the fibrous organic filler include aromatic polyamide fiber, rayon fiber, nylon fiber, polyester fiber, polypropylene fiber, pulp fiber, synthetic pulp and the like. In the present invention,
The average diameter of the fibrous filler needs to be smaller than the thickness of the pressure-sensitive adhesive layer. If the average diameter is more than the thickness of the pressure-sensitive adhesive layer, the adhesiveness to the metal surface will decrease. By including the powdery filler or the fibrous filler in the pressure-sensitive adhesive layer, pores are formed in the pressure-sensitive adhesive layer, and the oil component present at the contact interface with the metal easily passes through the pressure-sensitive adhesive layer. In particular, when a fibrous material is used as the filler, pores are formed, and due to the capillary phenomenon between the fibers, oil is efficiently sucked up, and the effect can be expressed with a small addition amount, Less likely to affect adhesiveness.

In the present invention, the powdered fillers may be used alone or in combination of two or more, or may be used in the form of one kind of fibrous filler or in combination of two or more. You may use it. Furthermore, one or more powdered fillers and one or more fibrous fillers may be used in combination. It is necessary that the powdery filler or the fibrous filler is contained in a proportion of 2 to 40% by weight, preferably 2 to 20% by weight, more preferably 5 to 10% by weight, based on the solid content of the pressure-sensitive adhesive. . If the content is less than 2% by weight, the effect of the present invention will not be sufficiently exhibited, and 4
If it exceeds 0% by weight, the adhesiveness tends to decrease.
The thickness of the filler-containing pressure-sensitive adhesive layer is usually 10
It is about 40 μm. In the pressure-sensitive adhesive sheet of the present invention,
If desired, a release sheet can be provided on the surface of the filler-containing pressure-sensitive adhesive layer. Examples of the release sheet include polyester, Teflon, polypropylene,
It is possible to use a plastic sheet such as polyethylene, or paper having releasability provided by a silicone resin or a nonionic surfactant. The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and a method conventionally used in the production of pressure-sensitive adhesive sheets can be adopted. For example, first, a pressure-sensitive adhesive containing a filler is prepared and then directly coated on the surface of an oil-absorbent sheet or an oil-absorbent sheet having a polymer base material laminated on the back surface and dried, or coated on a release sheet. The pressure-sensitive adhesive sheet of the present invention can be produced by forming the pressure-sensitive adhesive layer by transferring the oil-absorbent sheet to the surface of the oil-absorbent sheet or the surface of the oil-absorbent sheet having a polymer substrate laminated on the back surface. When the pressure-sensitive adhesive sheet of the present invention thus obtained is attached to a metal surface to which oil components such as rust-preventing oil and cutting oil are attached, the oil component passes through the filler-containing pressure-sensitive adhesive layer to the oil-absorbent sheet. As it is effectively absorbed, it adheres easily without removing the oil present on the metal surface. FIG. 1 is a configuration diagram of an example of a pressure-sensitive adhesive sheet of the present invention, in which a filler 5 is contained on the surface of an oil-absorbent sheet 3 laminated on a surface base material 1 with a pressure-sensitive adhesive layer or an adhesive 2. Adhesive layer 4 is formed,
Further, the structure in which the release sheet 6 is provided on the above is shown.

[0009]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The characteristics of the pressure-sensitive adhesive sheet were evaluated according to the methods described below. As an adherend, machine oil [Idemitsu Kosan
Co., Ltd., trade name: Daphne mechanic oil No68]
Stainless steel plate coated with 6 g / m ² and water-soluble cutting oil (30 parts by weight of refined mineral oil, 35 parts by weight of rust inhibitor, lubricant 1
Prepared with 0 part by weight and 25 parts by weight of anionic surfactant) Using a stainless steel plate coated with 6 g / m ² , after each sticking an adhesive sheet, pressure-bonding once with a 2 kg roller, 23 ° C., 65% RH A test was conducted in an atmosphere to determine initial adhesiveness, permanent adhesive strength, and adhesive residue after peeling. (1) Initial adhesiveness The adhesiveness after 5 minutes from application was judged according to the following criteria. ○: Adhesiveness is good ×: Adhesiveness is poor (2) Permanent adhesive strength (180 ° Peel Test) Twenty-four hours after application, the resistance value when peeled at a peeling speed of 300 mm / min was measured using a load cell type tensile tester. ,
The average value was determined (sample width 25 mm). (3) Adhesive residue after peeling The adhesive residue state after peeling in the test of (2) above was visually observed.

Example 1 76.5 parts by weight of butyl acrylate, 20.0 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of acrylic acid, 0.5 part by weight of hydroxyethyl methacrylate, azobisisobutyronitrile A mixed solution of 0.1 parts by weight and 150.0 parts by weight of toluene was polymerized in a nitrogen gas atmosphere at 70 ° C. for about 8 hours to obtain an acrylic copolymer. Further, to 100 parts by weight of the solid content of this acrylic copolymer, 0.5 parts by weight of a solid content of an isocyanate-based crosslinking agent [manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L] was added as a crosslinking agent.
Further, 5 parts by weight of pulp fine fibers having a fiber length of 50 to 150 μm and an average diameter of about 10 μm were added to prepare a coating liquid.
In advance, a 60 μm thick polypropylene film and 55
A non-sized surface base material is prepared by laminating a g / m ² non-sized paper as a surface base material, applying the coating solution on a release paper so that the thickness after drying is 25 μm, and drying. It was pasted on the paper side to prepare an adhesive sheet. The release paper was peeled off from this pressure-sensitive adhesive sheet and attached to a stainless steel plate coated with machine oil 6 g / m ² and a stainless steel plate coated with water-soluble cutting oil 6 g / m ² , respectively, and the characteristics thereof were evaluated. The results are shown in Table 1. Example 2 50.0 parts by weight of lauryl acrylate, 25.0 parts by weight of stearyl acrylate, 20.0 parts by weight of butyl acrylate,
A mixed solution of 5.0 parts by weight of acrylic acid, 0.1 parts by weight of azobisisobutyronitrile, and 150.0 parts by weight of toluene was polymerized at 70 ° C. for about 8 hours in a nitrogen gas atmosphere to obtain an acrylic resin having an oil absorption property. A polymer was obtained. Further, to 100 parts by weight of the solid content of this acrylic copolymer, 0.5 parts by weight of a solid content of an isocyanate-based crosslinking agent [manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L] was added as a crosslinking agent. Furthermore, 5 parts by weight of the above-mentioned pulp fine fiber was added to prepare a coating liquid. Using this coating liquid, the pressure-sensitive adhesive sheet was prepared by applying and drying in the same procedure as in Example 1. The characteristics of this pressure-sensitive adhesive sheet were evaluated in the same procedure as in Example 1. The results are shown in Table 1.

Example 3 To a mixed solution of 50 parts by weight of natural rubber, 30 parts by weight of polyterpene resin, 15 parts by weight of polybutene, 5 parts by weight of alkylphenol resin, and 150 parts by weight of toluene, 5 parts by weight of the above pulp fine fiber was added and coated. A working solution was prepared. Using this coating liquid, the pressure-sensitive adhesive sheet was prepared by applying and drying in the same procedure as in Example 1. The characteristics of this adhesive sheet are shown in Example 1.
Evaluation was performed in the same procedure as. The results are shown in Table 1. Example 4 0.1 part by weight of azobisisobutyronitrile was dissolved in a monomer compounding liquid consisting of 50.5 parts by weight of butyl acrylate, 44.5 parts by weight of 2-ethylhexyl acrylate, and 5.0 parts by weight of acrylic acid. did. Then, 50 parts by weight of the mixed solution was mixed with 100 parts by weight of an aqueous medium containing 1% by weight of an anionic surfactant, and the mixture was emulsified by using a homogenizer.
Polymerization was carried out for a period of time to obtain an acrylic copolymer as an emulsion solution. Further, to 100 parts by weight of the solid content of the acrylic copolymer, 5 parts by weight of the above-mentioned pulp fine fiber was added,
A coating liquid was prepared. Using this coating liquid, the pressure-sensitive adhesive sheet was prepared by applying and drying in the same procedure as in Example 1. The characteristics of this pressure-sensitive adhesive sheet were evaluated in the same procedure as in Example 1.
The results are shown in Table 1. Example 5 Lauryl acrylate 45.0 parts by weight, stearyl acrylate 20.0 parts by weight, butyl acrylate 30.0 parts by weight,
0.1 part by weight of azobisisobutyronitrile was dissolved in a monomer compounding liquid containing 5.0 parts by weight of acrylic acid. Then, 50 parts by weight of the mixed solution was mixed with 100 parts by weight of an aqueous medium containing 1% by weight of an anionic surfactant, and the mixture was emulsified by using a homogenizer. Polymerization was carried out for a period of time to obtain an acrylic copolymer as an emulsion solution. Furthermore, 5 parts by weight of the above pulp fine fibers were added to 100 parts by weight of the solid content of this acrylic copolymer to prepare a coating liquid. Using this coating liquid, the pressure-sensitive adhesive sheet was prepared by applying and drying in the same procedure as in Example 1. The characteristics of this adhesive sheet are shown in Example 1.
The procedure was evaluated. The results are shown in Table 1.

Example 6 Solid content of the acrylic copolymer obtained in Example 1 100
An isocyanate type cross-linking agent [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L] was added as a cross-linking agent in an amount of 0.5 parts by weight based on the solid content, and a fiber length of 50 to 15 was added.
A coating liquid was prepared by adding 5 parts by weight of rayon fine fibers having a diameter of 0 μm and an average diameter of about 12 μm. With this coating liquid,
A pressure-sensitive adhesive sheet was prepared by applying and drying in the same procedure as in Example 1. The characteristics of this pressure-sensitive adhesive sheet were evaluated in the same procedure as in Example 1. The results are shown in Table 1. Example 7 Solid content of 100 of the acrylic copolymer obtained in Example 1
An isocyanate type cross-linking agent [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L] was added as a cross-linking agent in an amount of 0.5 part by weight in terms of solid content, and the average particle size was 2 to 5 μm.
5 parts by weight of m clay was added to prepare a coating solution. Application of this coating solution in the same procedure as in Example 1,
It dried and the adhesive sheet was created. The characteristics of this pressure-sensitive adhesive sheet were evaluated by the procedure of Example 1. The results are shown in Table 1. Example 8 Solid content of 100 of the acrylic copolymer obtained in Example 1
An isocyanate type cross-linking agent [trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.] was added as a cross-linking agent in an amount of 0.5 part by weight in terms of solid content, and an average particle size of 5 to 10 was added.
A coating solution was prepared by adding 5 parts by weight of zeolite having a diameter of μm. Using this coating solution, coating and drying were performed in the same procedure as in Example 1 to prepare an adhesive sheet. The characteristics of this pressure-sensitive adhesive sheet were evaluated by the procedure of Example 1. The results are shown in Table 1. Comparative Example 1 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that fine pulp fibers were not added.
Its characteristics were evaluated. The results are shown in Table 1. Comparative Example 2 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 2 except that fine pulp fibers were not added.
Its characteristics were evaluated. The results are shown in Table 1. Comparative Example 3 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 3 except that fine pulp fibers were not added.
Its characteristics were evaluated. The results are shown in Table 1. Comparative Example 4 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 4, except that the fine pulp fibers were not added.
Its characteristics were evaluated. The results are shown in Table 1. Comparative Example 5 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 5, except that fine pulp fibers were not added.
Its characteristics were evaluated. The results are shown in Table 1.

[0013]

[Table 1]

[0014]

The pressure-sensitive adhesive sheet of the present invention comprises an oil-absorbent sheet and a filler-containing pressure-sensitive adhesive layer provided on the pressure-sensitive adhesive sheet, and exhibits excellent adhesion to a metal surface to which oil is adhered, without removing the oil. Shows sex. In this way, it is possible to attach without removing oil, so work efficiency is improved, rust does not occur at the place where the adhesive sheet is attached and its surroundings, and an unnecessary adhesive sheet can be removed. Even after peeling, no rust or adhesive residue is left on the peeling trace.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of an adhesive sheet of the present invention.

[Explanation of symbols]

1 Surface material 2 Adhesive layer or adhesive layer 3 oil absorbing sheet 4 Adhesive layer 5 filler 6 Release sheet

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C09J 7/02

Claims (4)

(57) [Claims] 1. A powdery filler having an average particle diameter smaller than the thickness of the pressure-sensitive adhesive layer and / or a fibrous filler having an average diameter smaller than the thickness of the pressure-sensitive adhesive layer on an oil-absorbent sheet, based on the pressure-sensitive adhesive solid content. An adhesive sheet provided with an adhesive layer containing 2 to 40% by weight. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the oil-absorbent sheet has a polymer base material laminated on the surface opposite to the pressure-sensitive adhesive layer. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the oil-absorbent sheet absorbs non-hydrophilic oil and / or hydrophilic oil. 4. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to claim 1, further comprising a release sheet.