JP2006249240A - Method for improving self-backside adhesive force, pressure-sensitive adhesive sheet and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving the self-backside adhesive force of a pressure-sensitive adhesive sheet. <P>SOLUTION: The method for improving the self-backside adhesive force of a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one side of a substrate comprises forming asperities on the self-backside of the substrate opposite to the side bearing the pressure-sensitive adhesive layer. The asperities has a surface roughness(Ra) meeting the relationship: 0.01μm<Ra<10μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for improving the self-back surface adhesive force such as a pressure-sensitive adhesive sheet, and in particular, a method capable of improving the self-back surface adhesive force to such an extent that it can be firmly bonded to the self-back surface in a short time. Etc.

  The pressure-sensitive adhesive sheet has a basic structure in which a pressure-sensitive adhesive layer is provided on one side of a support such as a plastic film. Therefore, when such a pressure-sensitive adhesive sheet is attached to an adherend, the other surface on which the pressure-sensitive adhesive layer of the support is not formed is located on the surface. One surface located on the surface when pasted in this way is called the “self-back surface” of the pressure-sensitive adhesive sheet.

  Examples of pressure-sensitive adhesive sheets include conventional adhesive sheets obtained by applying and drying an organic solvent-type pressure-sensitive adhesive on a support such as a plastic film. In recent years, support and pressure-sensitive adhesives have been used. Various pressure-sensitive adhesive sheets are provided in which the adhesive residue and the decrease in adhesive force are prevented by changing the material, and there are relatively various materials (see, for example, Patent Documents 1 and 2).

JP 2000-230115 A JP 2000-248236 A

  In the use of the pressure-sensitive adhesive sheet, after sticking the pressure-sensitive adhesive sheet to the adherend, the same adhesive sheet or other An adhesive sheet or an adhesive tape may be overlaid, but the back surface may not be able to exhibit sufficient adhesive strength. Note that the “self-back surface adhesive force” here is not a surface having an adhesive function such as an adhesive layer or the like, but depending on the state of the own surface, It means the degree of improving the mutual adhesion or adhesiveness with the other adhesive layer. Therefore, for example, when the same adhesive layer is attached to two types of back surfaces, the back surface that provides stronger adhesion or adhesiveness with the adhesive layer is "High".

  The self-adhesive force when the same adhesive sheet or the like is laminated on the self-back surface of the pressure-sensitive adhesive sheet depends on the composition of the support constituting the back surface. For example, the pressure on the back surface of a pressure-sensitive adhesive sheet using a polyolefin sheet having a low polarity as a support was low, making it difficult to control. When the self-back surface adhesive force is low, the adhesive sheet and the like that are overlaid are easily peeled off from the overlapped portion and cannot be used for, for example, box sealing or waterproofing.

  This invention is made | formed in view of the said situation, The subject is providing the method etc. which improve self-back surface adhesive force, such as a pressure-sensitive adhesive sheet.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, experimented, and studied. As a result, fine irregularities are formed on the exposed surface (back surface) on which the adhesive layer of the support of the pressure-sensitive adhesive sheets is not formed. As a result, it has been found that the adhesive strength of the back surface with each adhesive layer is greatly improved when the same or the same kind of adhesive sheets as well as other adhesive sheets are overlaid.

  The present invention has been made based on such knowledge. That is, the method for improving the self-back adhesive strength of the pressure-sensitive adhesive sheets of the present invention is the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one side of the support. It is characterized in that the self-back surface adhesive force of the pressure-sensitive adhesive sheets is improved by forming fine irregularities on the self-back surface that is the surface opposite to the surface having the surface.

  The fine irregularities are expressed as 0.01 μm <Ra <10 μm in terms of surface roughness (Ra).

  In the present invention, the fine irregularities may be formed using at least one of the group consisting of a) sand blasting, b) polishing, c) embossing, d) etching, and e) electric discharge. it can.

  The method for producing pressure-sensitive adhesive sheets of the present invention has a pressure-sensitive adhesive layer on one side of a support, and a surface on the back side of the support opposite to the side having the pressure-sensitive adhesive layer. A method for producing a pressure-sensitive adhesive sheet having a self-rear surface having fine irregularities having a roughness (Ra) of greater than 0.01 μm and less than 10 μm, wherein the fine irregularities are a) sandblast treatment, b It is characterized in that it is formed using at least one of a) polishing process, c) embossing process, d) etching process, and e) discharge process.

  Here, the fine irregularities are formed directly on the surface of the support, or after temporarily forming fine irregularities on another sheet, such as a release liner, the irregularities are transferred to the surface of the support. Thus, pressure-sensitive adhesive sheets can be formed.

  The pressure-sensitive adhesive sheets of the present invention have a pressure-sensitive adhesive layer on one side of a support, and a) a sandblasting treatment on the back surface of the support opposite to the surface having the pressure-sensitive adhesive layer. B) polishing treatment, c) embossing treatment, d) etching treatment, and e) fine irregularities formed by using at least one kind of discharge treatment.

  According to the present invention, the self-back surface adhesive force such as a pressure-sensitive adhesive sheet is improved, and the self-back surface adhesive force is improved to such an extent that it can be firmly adhered to the back surface in a short time and can be peeled off after use. Can do. Therefore, after the pressure-sensitive adhesive sheets are attached to the adherend, the same or the same type of pressure-sensitive adhesive sheets or other adhesive sheets can be overlaid to improve the sealing performance of the adherend, from the adherend. Can be prevented from falling off.

BEST MODE FOR CARRYING OUT THE INVENTION

  This invention can improve the self-back surface adhesive force of a pressure-sensitive adhesive sheet by providing a fine unevenness | corrugation in the self-back surface of pressure-sensitive adhesive sheets. Here, the pressure-sensitive adhesive sheets have a structure having a pressure-sensitive adhesive layer on one surface of the support. For example, fine irregularities are provided on the surface of the support opposite to the surface having the pressure-sensitive adhesive layer.

  In the present invention, as described above, the factor that improves the self-back surface adhesive force is the fine unevenness provided on the self-back surface. When expressed by the surface roughness (Ra), 0.01 μm <Ra < 10 μm. Considering the case where the surfaces are brought into close contact with each other, it is expected that when the smooth surface and the concavo-convex surface are brought into close contact with each other, the contact area is considerably reduced and the adhesive force is lowered than in the case where the smooth surfaces are brought into close contact with each other. . However, in practice, the adhesion or adhesion of the pressure-sensitive adhesive layer to the back surface on which the fine uneven surface of the present invention is formed is greatly improved. This is because the pressure-sensitive adhesive layer is flexible, and the back surface of the pressure-sensitive adhesive sheet according to the present invention has fine irregularities suitable for followability based on the flexibility of the pressure-sensitive adhesive layer. It is considered that the adhesive layer can be closely adhered to follow the irregularities on the back surface. This can be confirmed by cutting the laminated body in a state where another adhesive sheet or the like is laminated on the back surface in the layer thickness direction and observing the adhesive interface.

  As described above, the factor for improving the self-back surface adhesive strength of the pressure-sensitive adhesive sheets is the fine unevenness formed on the back surface, for example, the surface roughness within a predetermined range, and at least the material of the support is not the main factor. . Therefore, in the present invention, there is no need to limit the constituent material and composition of the support, and the present invention can be applied to various conventional pressure-sensitive adhesive sheets. That is, the support may be any material that can form a film having appropriate flexibility. Suitable materials include polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, polyurethane resin, polyamide resin, Examples thereof include plastics such as acrylic resins and vinyl chloride resins. For example, the support can be formed using a urethane-acrylic hybrid aqueous dispersion, which is known as an aqueous dispersion of a composite of a urethane prepolymer and an acrylic polymer. This urethane-acrylic hybrid aqueous dispersion is prepared by preparing a urethane-acrylic hybrid aqueous dispersion, and then adding a non-tackifying monomer containing a (meth) acrylic acid alkyl ester as a main component thereto, followed by polymerization treatment. Can be obtained.

  The support may be made of any one of the above materials, or may be a film formed by kneading any material, or a plurality of materials may be alternately arranged in a tile shape. It may be a film formed or a laminated film in which a plurality of films are laminated. If necessary, additives such as fillers, pigments, anti-aging agents and lubricants may be blended.

  The thickness of the support is not particularly limited and can be appropriately selected depending on the application and purpose. In general, the thickness is preferably 10 μm to 200 μm.

  The method for forming a support in the present invention is not particularly limited, and a conventional method for forming a support can be used as it is. For example, using a uniaxial or biaxial extruder, etc., a resin that has been heat-melted and kneaded into a pellet is formed into a film (sheet) having a predetermined thickness by a T-die method, an inflation method, a calendar method, a rolling method, or the like. The support can be obtained by molding. The composition may be kneaded and immediately formed into a film, or may be formed by various coating methods using hot melt, or by a method in which a casting process and a drying process are performed from a solution state.

The processing means for providing fine irregularities on the surface of the support is not particularly limited. As described above, a) sand blasting, b) polishing, c) embossing, d) etching, e) less discharge processing. Can also be suitably used.
The sand blasting process a) is a process for forming fine irregularities by spraying air or water and an abrasive such as sand or metal pieces at a high speed and then removing the abrasive with water or a pressure-sensitive adhesive sheet. Means. In carrying out this treatment, the roughness of the fine irregularities can be appropriately adjusted depending on the type and shape of the abrasive, the spraying speed, and the spraying amount.

  As the polishing process of b), a conventional method can be used. The back surface of the support may be polished with an abrasive, may be polished with a metal brush or the like, or may be polished with sandpaper or the like. At this time, the roughness of fine irregularities can be appropriately adjusted by changing the type of each abrasive.

  Various methods are used for the embossing of c). When forming into a film as a support, embossing roll, satin or drum with matte surface, embossing belt may be passed to transfer fine unevenness, embossing treatment to release paper to be cast, etc. The fine unevenness formed by this embossing process may be transferred to the support, or the unevenness may be formed by heating and pressing the film as the support. At this time, the roughness of fine irregularities can be adjusted by changing the emboss pattern.

  The etching process d) is a processing means for etching the surface of the support film with an alkali saponification solution or an organic solvent. At this time, the roughness of the fine irregularities can be adjusted by changing the type of alkali saponification solution or organic solvent and the treatment time.

  As the discharge treatment of e), a general method such as corona treatment or electron beam irradiation is used. At this time, the roughness of fine irregularities can be adjusted by changing the irradiation intensity and the processing time.

  Each of these treatments may be performed after forming a film as a support, or after forming a pressure-sensitive adhesive sheet. Furthermore, these treatments may be performed directly on the support or the pressure-sensitive adhesive sheet, or the support may be formed on this surface of a release paper or the like on which these treatments have been performed in advance to transfer the unevenness.

  In the present invention, “surface roughness”, which is one of the expression methods indicating the size of fine irregularities formed on the back surface, is based on JIS-B 0601, and Ra is the center line average roughness. Show. The center line average roughness (Ra) of the fine irregularities formed by the above-described treatment needs to be 0.01 μm <Ra <10 μm, preferably 0.01 μm <Ra <3 μm, more preferably 0 0.05 μm <Ra <1 μm. When the center line average roughness (Ra) of fine unevenness is 0.01 μm or less, the increase in surface area due to unevenness is insufficient, and when exceeding 10 μm, the adhesive layer cannot follow the formed unevenness, As a result, the contact area between the pressure-sensitive adhesive layer and the own back surface is reduced, and the self-back surface adhesive force is reduced.

  The pressure-sensitive adhesive sheets according to the present invention have a pressure-sensitive adhesive layer on one surface of a support, and the pressure-sensitive adhesive layer can be formed using a pressure-sensitive adhesive or the like. The pressure-sensitive adhesive can be used without any particular limitation as long as it has an adhesive property such as an appropriate adhesive force and holding force. For example, a pressure-sensitive adhesive layer of a conventionally known pressure-sensitive adhesive sheet A pressure-sensitive adhesive used to form the film can be used. Specific examples include pressure-sensitive adhesives such as acrylic, rubber-based, urethane-based, and polyester-based adhesives, which can be appropriately used depending on the purpose and application. These pressure-sensitive adhesives may be used singly or as a mixture of a plurality of types. In addition, the pressure-sensitive adhesive layer may have a single-layer structure or a structure composed of a plurality of layers. When the pressure-sensitive adhesive layer is composed of a plurality of layers, the layers constituting the pressure-sensitive adhesive layer may be the same or different. Furthermore, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer may contain additives such as a crosslinking agent, a tackifier resin, a compatible component, a filler, a pigment, and an anti-aging agent, if necessary.

  A method for forming the pressure-sensitive adhesive layer is not particularly limited, and a conventionally known method can be employed. For example, it may be formed by directly applying a pressure-sensitive adhesive to one side of the support by a hot melt method, or a solvent-based pressure-sensitive adhesive or an emulsion-based pressure-sensitive adhesive may be applied to one side of the support. It may be formed by applying and drying, or alternatively, these pressure-sensitive adhesives may be applied to release paper or the like to form a pressure-sensitive adhesive layer in advance, and this pressure-sensitive adhesive layer is bonded to a support. Alternatively, the pressure-sensitive adhesive layer may be formed simultaneously with the formation of the support. Alternatively, a part of the pressure-sensitive adhesive monomer that forms the pressure-sensitive adhesive in advance is polymerized to form a prepolymer having an appropriate viscosity, and after applying this prepolymer, radiation or black light is applied. The adhesive layer may be formed by irradiating light such as. In that case, you may use a primer, a lubricant, etc. as needed.

As described above, the present invention can be applied to conventional pressure-sensitive adhesive sheets produced by applying and drying an organic solvent-type pressure-sensitive adhesive on a support such as a plastic film. Applicable to relatively recent pressure-sensitive adhesive sheets such as pressure-sensitive adhesive sheets having a support made from a urethane-acrylic hybrid aqueous dispersion as disclosed in Patent Documents 1 and 2 . The latter pressure-sensitive adhesive sheets may employ a manufacturing process in which an adhesive layer is formed at the same time when the support is formed. In such a case, it is used when forming the support. The embossing irregularities are formed on the peeling surface for film formation, and the support is formed using the peeling surface.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical idea of the present invention. The surface roughness (centerline average roughness Ra) was determined based on JIS-B 0601.

Example 1
A 75 μm thick polyethylene terephthalate sheet was previously sandblasted and further peeled to obtain a release liner for forming a support film. A polyurethane dimethylformamide solution was applied to the release liner so that the thickness after drying was 50 μm, and dried at 160 ° C. for 5 minutes to form a film-like support (thickness 50 μm). A polyacrylic pressure-sensitive adhesive layer having a thickness of 35 μm was bonded to this support to form a pressure-sensitive adhesive sheet having a release liner on the back of the support. The surface roughness (Ra) of the back surface of the obtained pressure-sensitive adhesive sheet was 0.3 μm.

(Example 2)
After the ethylene-vinyl copolymer resin pellets obtained by heating and kneading with a biaxial stretching extruder are heated and melted and extruded with a T die, they are passed through an embossed cooling roll to obtain a thickness. A film having a thickness of 60 μm was obtained. The obtained film was used as a support, and a 35 μm-thick polyacrylic pressure-sensitive adhesive layer was bonded to the support to form a pressure-sensitive adhesive sheet. The surface roughness (Ra) of the back surface of the obtained pressure-sensitive adhesive sheet was 0.5 μm.

(Comparative Example 1)
In Example 1, a pressure-sensitive adhesive sheet was formed in the same manner as Example 1 except that the polyethylene terephthalate sheet was not subjected to sandblasting. The surface roughness (Ra) of the back surface of the obtained pressure-sensitive adhesive sheet was 0.005 μm.

(Comparative Example 2)
In Example 2, as a cooling roll used when forming a film for a support, a cooling roll in which embosses in which squares each having a side dimension of 50 μm are arranged vertically and horizontally are formed every 100 μm is used. In the same manner as in 2, a pressure-sensitive adhesive sheet was formed. The surface roughness (Ra) of the back surface of the obtained pressure-sensitive adhesive sheet was 15 μm.

The pressure-sensitive adhesive sheets obtained in the above Examples and Comparative Examples were evaluated by performing the following tests. The results are shown in Table 1.

(Measurement of self-back adhesion)
The pressure-sensitive adhesive sheet was cut into a size of 20 mm × 100 mm and a size of 10 mm × 60 mm to prepare a test piece A for measurement and a test piece B for measurement. A pressure-sensitive adhesive sheet (test specimen A for measurement) having a size of 20 mm × 100 mm was attached to the surface of the bakelite plate using a roller, and the pressure-sensitive adhesive sheet was further cut into a 10 mm × 60 mm rectangular shape on the pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet (test piece B for measurement) was reciprocated once with a 2 kg roller, and was pasted and overlaid. Then, after 30 minutes had passed, the test piece B for measurement that was overlaid was peeled from the back surface of the test piece A for measurement in the direction of 90 ° at a peeling speed of 300 mm / min. The peeling resistance stress at that time was defined as the self-back adhesive force.

  As is clear from Table 1, the pressure-sensitive adhesive sheet having fine unevenness on the back surface obtained in Examples 1 and 2 has high self-back surface adhesive force, but the fine unevenness obtained in Comparative Example 1 is high. It was found that the pressure-sensitive adhesive sheet that was not provided and the pressure-sensitive adhesive sheet obtained in Comparative Example 2 in which the unevenness was not fine had low self-back surface adhesive force. That is, the pressure-sensitive adhesive sheets of Examples 1 and 2 can improve the self-back adhesive strength to such an extent that the pressure-sensitive adhesive sheets can be firmly bonded to the self-back surface in a short time and can be peeled off after use. did it.

As described above, the method for improving the self-back adhesion of the present invention can be applied to conventional pressure-sensitive adhesive sheets. By providing fine irregularities on its back surface, when it is laminated on this back surface, it can improve the adhesion or adhesion between the pressure-sensitive adhesive layer and attach the pressure-sensitive adhesive sheets. It can be suitably applied to a layering process for the purpose of sealing after sticking to the body and preventing the part from being detached.

Claims (6)

  In pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer on one surface of the support, fine irregularities are formed on the back surface of the support opposite to the surface having the pressure-sensitive adhesive layer. The self-back surface adhesive force is improved by improving the self-back surface adhesive force of the pressure-sensitive adhesive sheets.   The method for improving the self-back surface adhesive force according to claim 1, wherein the surface roughness (Ra) of the fine irregularities is 0.01 μm <Ra <10 μm.   The fine irregularities are formed using at least one of the group consisting of a) sand blasting, b) polishing, c) embossing, d) etching, and e) electric discharge. Item 3. A method for improving the self-back surface adhesive force according to any one of Items 1 and 2.   A surface having a pressure-sensitive adhesive layer on one side of the support, and having a surface roughness (Ra) greater than 0.01 μm and 10 μm on the back surface of the support opposite to the surface having the pressure-sensitive adhesive layer. A method for producing a pressure-sensitive adhesive sheet having a self-back surface having fine irregularities that is less than 1, wherein the fine irregularities are a) sand blasting, b) polishing, c) embossing, d) etching. E) A method for producing a pressure-sensitive adhesive sheet, characterized in that it is formed using at least one kind of discharge treatment.   Form the fine irregularities directly on the surface of the support, or temporarily form fine irregularities on another sheet and then transfer the irregularities to the surface of the support to form pressure-sensitive adhesive sheets The method for producing a pressure-sensitive adhesive sheet according to claim 4.   A support has a pressure-sensitive adhesive layer on one side, and a) a sand blasting process, b) a polishing process, and c) an embossing process on the back surface of the support opposite to the side having the pressure-sensitive adhesive layer. D) Etching treatment, e) Pressure-sensitive adhesive sheets having fine irregularities formed by using at least one kind of discharge treatment.