JP2015190998A - Heat-proof and alkali-proof pressure sensitive adhesive label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-proof and alkali-proof pressure sensitive adhesive label preventing the label from being peeled from a base material even when the label is subjected to a high-temperature and high-concentration alkali treatment, an acid cleaning treatment as necessary, and further a high-temperature treatment such as 450°C.SOLUTION: A heat-proof and alkali-proof pressure sensitive adhesive label 11 comprises a laminated body including: a fist silicone adhesive layer 13 with the film thickness of 25 μm or more consisting of a silicone adhesive, formed on a heat-proof and alkali-proof base material 12; a second adhesive layer 14 with the film thickness of more than 10 μm and less than 30 μm consisting of an acrylic pressure sensitive adhesive, formed on the first adhesive layer 13; a release sheet 15 formed on the second adhesive layer as necessary; and a surface treatment layer 16 such as a printing layer on an opposite surface of the surface where the adhesive layer of the base material 12 is provided.

Description

  The present invention relates to an adhesive label excellent in heat resistance and alkali resistance. More specifically, it can be applied to adherends such as hot-dip galvanized steel sheets with an alkali treatment process and a high-temperature treatment process, and can be used for the management of manufacturing processes and products after treatment. The invention relates to an alkali-resistant adhesive label.

  Conventionally, the manufacturing material of various products such as industrial products has been attached with a management label printed with various individual information such as manufacturing number, management number, management information, barcode, etc., read and input to a computer etc. to manufacture the product It is widely performed to manage manufacturing processes and processing conditions in each process, further manage manufacturing history, or manage products after manufacturing. In general, an adhesive label is used as such a management label. However, there are cases where acid or alkali treatment, high temperature treatment, etc. are performed in the process until the final product is obtained, and for this reason, it is necessary for the control label to withstand such treatment and maintain adhesiveness. Is done.

  For example, when it is subjected to a high temperature, a heat-resistant label that can withstand the temperature and retains adhesiveness is known. Conventionally, for example, a silicone-based pressure-sensitive adhesive has been used as the pressure-sensitive adhesive for such a heat-resistant label (see, for example, Patent Documents 1 and 2). However, a label using a silicone-based pressure-sensitive adhesive has a problem of peeling after a strong alkali treatment. On the other hand, an acrylic pressure-sensitive adhesive generally used as a pressure-sensitive adhesive for adhesive labels is resistant to alkali treatment, but decomposes and evaporates at a temperature of 350 ° C. or higher (see, for example, Patent Document 2), and a temperature as high as 450 ° C. Has a problem that the adhesive is lost due to carbonization of the adhesive and peels off.

  2. Description of the Related Art Conventionally, it has been widely practiced to galvanize a steel plate or the like to prevent corrosion of steel, and a hot dip galvanizing method is known as one of the plating methods. This method has an advantage that a thick plating layer can be easily formed at a low cost as compared with the electrogalvanizing method. This hot-dip galvanized steel material is used as various products in a wide range of fields such as steel sheets for automobile manufacturing, guardrails, fences, signposts, handrails, stairs, safety fences, outdoor structures, bolts, steel pipes, etc. .

  In the hot dip galvanization of this steel material, the following steps are usually taken. That is, first, the degreasing treatment of the steel material is performed in the pretreatment process. In this degreasing process, high-concentration alkaline water of about 10 to 20% is used, and processing at a high temperature of about 70 ° C. is performed. Thereafter, washing with water, acid washing (for example, washing at room temperature with 5 to 20% acid), water washing, and flux treatment are performed, and then the steel material is immersed in a hot galvanizing bath at about 430 to 450 ° C. for about 5 minutes. Each process of cooling, finishing is performed. Thus, in hot dip galvanization, high temperature strong alkali treatment as a pretreatment, subsequent strong acid cleaning treatment, and further plating treatment at a high temperature of 450 ° C. are performed. When a label using an adhesive as an adhesive is affixed to a steel material as a management label, there is a problem that the label peels off at any step of the hot dip galvanization, and the steel material is managed during hot dip galvanization of the adhesive label It was thought that it could not be used as a label. For this reason, management of steel materials during hot dip galvanization has been done by engraving management information such as a management number on an iron plate and sticking it to the steel material, but there are problems with poor workability and character information For this reason, the amount of information is limited.

JP-A-9-26751 JP 2004-13054 A

  The present invention has been made in the situation as described above. When high-temperature and high-concentration alkali treatment is performed thereafter, and acid cleaning treatment is performed as necessary, and further high-temperature treatment such as 450 ° C. is performed, for example, hot dip galvanization of steel materials is performed. Even in such a case, it is an object to provide a heat-resistant and alkali-resistant pressure-sensitive adhesive label that does not peel from the base material, and therefore can be preferably used as a management label for materials and products accompanying such treatment. Is.

  As a result of intensive studies and studies, the present inventor has used an acrylic pressure-sensitive adhesive and a silicone pressure-sensitive adhesive that have been conventionally used as a single layer as a pressure-sensitive adhesive layer as two layers. The order of lamination of the adhesive is to be provided with a silicone adhesive layer on the substrate, an acrylic adhesive layer is provided on the silicone adhesive layer, and the thickness of these adhesive layers is set to a specific thickness. Based on this new finding, it is possible to obtain a heat- and alkali-resistant pressure-sensitive adhesive label that does not peel from the substrate even after high-temperature and high-concentration alkali treatment and high-temperature treatment such as 450 ° C. This makes the present invention.

That is, the present invention relates to the following heat-resistant and alkali-resistant adhesive labels.
(1) A first pressure-sensitive adhesive layer made of a silicone-based pressure-sensitive adhesive and a second pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive are laminated on the first pressure-sensitive adhesive layer, and the first pressure-sensitive adhesive layer The heat-resistant and alkali-resistant pressure-sensitive adhesive label is characterized in that the thickness of the second pressure-sensitive adhesive layer is 10 μm or more and less than 30 μm.

(2) The heat and alkali resistance according to (1) above, wherein the thickness of the first pressure-sensitive adhesive layer is 30 μm or more and the thickness of the second pressure-sensitive adhesive layer is 15 to 25 μm. Adhesive label.

(3) The heat- and alkali-resistant pressure-sensitive adhesive label according to (1) or (2) above, wherein the second pressure-sensitive adhesive layer further contains a silicone resin.

(4) The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to any one of (1) to (3) above, wherein a release sheet is provided on the second pressure-sensitive adhesive layer.

(5) The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to any one of (1) to (4) above, which has a surface treatment layer on the side opposite to the first pressure-sensitive adhesive layer of the substrate.

(6) The heat-resistant and alkali-resistant adhesive label according to (5), wherein the surface treatment layer is a printing layer.

  Conventionally, in a hot dip galvanizing process, a steel sheet is subjected to high concentration, high temperature alkali treatment and high temperature treatment at about 450 ° C., and there has been no label that can withstand both of these treatments. Since the heat-resistant and alkali-resistant pressure-sensitive adhesive label of the present invention has resistance to both high temperature and alkali, it is attached to an adherend that is subjected to both steps of alkali treatment and high temperature treatment, for example, high temperature treatment of about 450 ° C. Even in this case, the label does not peel off in these steps. Therefore, even if the heat-resistant and alkali-resistant adhesive label of the present invention is affixed to a steel sheet, the label does not peel off after the hot dip galvanizing process, and can be used as a management label. Can be managed. This makes it possible to use an iron plate with characters on it as a management label in hot dip galvanization, eliminating the need to attach it to the steel plate, greatly improving workability, and thus improving and managing productivity. An increase in the table is expected. In addition to the hot dip galvanization, the heat-resistant and alkali-resistant pressure-sensitive adhesive label of the present invention can be effectively used when both high-temperature treatment and high-temperature treatment with high-concentration alkali are performed.

It is typical sectional drawing of the Example of the heat-resistant and alkali-proof adhesive label of this invention. It is typical sectional drawing of the other Example of the heat-resistant and alkali-proof adhesive label of this invention.

Hereinafter, the heat-resistant and alkali-resistant adhesive label of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of an embodiment of the heat-resistant and alkali-resistant pressure-sensitive adhesive label of the present invention, and FIG. 2 is a schematic cross-sectional view of another embodiment of the heat-resistant and alkali-resistant pressure-sensitive adhesive label of the present invention. Since FIG. 1 and FIG. 2 are for explaining the present invention, the thickness of the layer is expressed differently from the actual thickness. Moreover, in this invention, an adhesive label is not restricted to what was cut | disconnected in the label form, but includes forms, such as an adhesive sheet and an adhesive tape.

  As shown in FIG. 1, the heat-resistant and alkali-resistant pressure-sensitive adhesive label 1 of the present invention includes a label base material 2, a first pressure-sensitive adhesive layer 3 made of a silicone-based pressure-sensitive adhesive, and a second pressure-sensitive adhesive layer 4 made of an acrylic pressure-sensitive adhesive. Is included.

  The substrate 1 may be any material as long as it is alkali-resistant and does not decompose at a high temperature of about 450 ° C. The alkali resistance is not particularly limited as long as the base material is not substantially affected by dissolution or the like in a high-temperature alkali treatment at a high concentration of about 20% and a high temperature of about 70 ° C. Examples of such alkali resistance and heat resistance include metal foils such as copper, silver, and gold, resin films such as polyimide, glass fiber paper, ceramic fiber paper, and aramid fiber paper. Resins such as aluminum and PEEK (polyetheretherketone) are also known as refractory metals and resins, but aluminum has a problem in terms of alkali resistance, and PEEK has a heat resistance at a temperature of about 450 ° C. There is a problem. Considering the cost and the like, a polyimide film is preferable as the base material of the heat-resistant and alkali-resistant pressure-sensitive adhesive label of the present invention. The thickness of the substrate may be arbitrary, and for example, a film having a thickness of about 10 to 125 μm is generally used.

  On the other hand, as the silicone pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer, any of conventionally known addition-type and peroxide-curing type silicone-type pressure-sensitive adhesives can be used. preferable. Addition-type silicone pressure-sensitive adhesives include, for example, those composed of vinyldimethylpolysiloxane at both ends, both ends dimethylpolysiloxane as a crosslinking agent and a catalyst, and diorganosiloxane such as polydimethylsiloxane having a residual silanol group (SiOH) at the end. Examples thereof include a polysiloxane polymer and an organohydrogenpolysiloxane having at least two SiH groups in the molecule as a crosslinking agent and a catalyst. As the catalyst, platinum-based catalysts such as chloroplatinic acid, a complex of chloroplatinic acid and an olefin, and a complex of chloroplatinic acid and vinylsiloxane are used. As described above, the silicone-based pressure-sensitive adhesive that can be used in the present invention is not limited to those specifically exemplified.

  As the addition type silicone pressure-sensitive adhesive, for example, KR3700, KR3701, X-40-3240, X-40-3270 manufactured by Shin-Etsu Silicone, SD4570, 4600FC, SD4580, SD4584, SD4585 manufactured by Toray Dow Corning are preferable in the present invention. Used. In the case of an addition-type silicone pressure-sensitive adhesive layer, the heat-drying temperature of the pressure-sensitive adhesive layer is preferably 100 to 130 ° C.

  On the other hand, the acrylic pressure-sensitive adhesive includes, as its constituent components, a main monomer for developing tackiness, a comonomer that increases cohesion, a functional group for reacting with a crosslinking agent, and for improving adhesion. The copolymer of the monomer which has can be mentioned, It can also bridge | crosslink using a crosslinking agent, and a thing with high alkali resistance is preferable.

  Examples of the main monomer include alkyl acrylates having 2 to 14 carbon atoms such as ethyl acrylate, n-butyl acrylate, and n-octyl acrylate, alkyl esters such as isobutyl methacrylate and n-octyl methacrylate. Examples thereof include alkyl methacrylate having 4 to 14 carbon atoms, and two or more of these may be used in combination.

  Examples of the comonomer for increasing the cohesive force include methyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and further styrene, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, and the like. Two or more of them may be used in combination.

  Furthermore, as a monomer having a functional group for improving the adhesive force and reacting with the crosslinking agent, monocarboxylic acids such as acrylic acid and methacrylic acid, polycarboxylic acids such as maleic acid and glutamic acid, These anhydrides, and further, carboxylic acid derivatives having a hydroxy group such as hydroxyethyl methacrylate and hydroxypropyl methacrylate are exemplified, and two or more of these may be used in combination.

  As the cross-linking agent, any cross-linking agent including polyisocyanate compounds, epoxy compounds, melamine resins, urea resins, dialdehydes, methylol polymers and the like can be selected and used. A polyisocyanate compound, which is a compound having two or more, is preferred as a crosslinking agent. Specific examples of the polyisocyanate crosslinking agent include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate and trimethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, methylenebis (cyclohexyl isocyanate) and cyclohexane diisocyanate. An aromatic diisocyanate such as xylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate and biphenylene diisocyanate; These can be used alone or in combination of two or more. Further, these trimethylolpropane adduct bodies, burette bodies reacted with water, trimers having an isocyanurate ring, and the like are also included.

  Moreover, as a commercial item of isocyanate as a crosslinking agent, for example, Takenate D110 (manufactured by Mitsui Chemicals) which is a trimethylol propane adduct of xylene diisocyanate, Coronate L (manufactured by Nippon Polyurethane Industry) which is a trimethylol propane adduct of toluene diisocyanate ), Duranate TPA-100 (manufactured by Asahi Kasei Chemicals) which is a hexamethylene diisocyanate trimer, and Coronate HL (manufactured by Nippon Polyurethane Industry) which is a trimethylol propane adduct of hexamethylene diisocyanate.

  Furthermore, in the present invention, as the acrylic pressure-sensitive adhesive, for example, butyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate or the like is used as a main monomer, and acrylic acid or the like is used as a monomer for reaction with a crosslinking agent. What consists of a copolymer copolymerized and a crosslinking agent is mentioned as a preferable thing. The curing temperature at this time is preferably 80 to 100 ° C.

  If desired, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a silane coupling agent, a filler and the like can be added to the second pressure-sensitive adhesive layer. Furthermore, in order to improve heat resistance with an acrylic adhesive, a silicone resin may be further added. As the silicone resin, a hydroxyl group-containing methylphenyl silicone can be preferably used. When the silicone resin is used, for example, the silicone resin may be used in an amount of 5 to 15 parts by weight and the crosslinking agent isocyanate may be used in an amount of about 0.4 parts by weight with respect to 100 parts by weight of the acrylic pressure-sensitive adhesive. Preferred examples of the silicone resin include SILRES K, SILRES REN50 manufactured by Asahi Kasei Wacker Silicone, XIAMETER RSN-0804 RESIN manufactured by Toray Dow Corning, and KR9218 manufactured by Shin-Etsu Silicone.

  In the pressure-sensitive adhesive label of the present invention, the first pressure-sensitive adhesive layer maintains the adhesiveness of the label to the substrate at a temperature of 450 ° C., while the second pressure-sensitive adhesive layer prevents the label from peeling off during the alkali treatment. It has a role. When the pressure-sensitive adhesive layer is exposed to a high temperature of 450 ° C., the acrylic pressure-sensitive adhesive of the second pressure-sensitive adhesive layer that adheres to the adherend is decomposed, dissipated, and carbonized, and the adhesive ability is lost. It is considered that the silicone pressure-sensitive adhesive of the first pressure-sensitive adhesive layer flows and the first pressure-sensitive adhesive contacts the adherend, and as a result, the adhesive force between the label and the adherend is maintained. At this time, it is preferable that the first pressure-sensitive adhesive layer has a thickness of 25 μm or more, and the second pressure-sensitive adhesive layer has a thickness of more than 10 μm and less than 30 μm. Furthermore, the thickness of the silicone pressure-sensitive adhesive layer of the first pressure-sensitive adhesive layer is more preferably 30 μm or more, while the thickness of the acrylic pressure-sensitive adhesive layer of the second pressure-sensitive adhesive layer is preferably 15 μm to 25 μm. . When the thickness of the first pressure-sensitive adhesive layer is less than 25 μm, there is a greater tendency for the label to peel off during the high heat treatment at 450 ° C., while the thickness of the second pressure-sensitive adhesive layer is 10 μm or less. When the layer thickness is 30 μm or more on the contrary, there is a greater tendency for the label to be peeled off during the high heat treatment at 450 ° C. The upper limit of the thickness of the silicone-based pressure-sensitive adhesive layer is not particularly limited. However, if the thickness exceeds 30 μm, there is no significant change in the effect even if the thickness changes, and no effect commensurate with the increased thickness is produced. Therefore, the thickness is usually 50 μm or less from an economic viewpoint.

  In FIG. 2, the preferable aspect of the alkali-resistant adhesive label which is another Example of the heat-resistant and alkali-resistant adhesive label of this invention is shown. In the figure, 11 is a heat and alkali resistant adhesive label, 12 is a substrate, 13 is a first adhesive layer, 14 is a second adhesive layer, 15 is a release sheet, and 16 is a surface treatment layer. . The base material, the first pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer are as described above, and the description thereof is omitted here.

  The release sheet 15 is provided on the second adhesive layer 14 in the heat-resistant and alkali-resistant pressure-sensitive adhesive label of FIG. As the release sheet, a conventionally known or well-known release sheet, such as a release paper, is arbitrarily used. As the release paper, for example, glassine paper, polylamination paper, polyester film, polypropylene film that has been subjected to silicone release treatment, or the like is used.

  Further, the heat-resistant and alkali-resistant pressure-sensitive adhesive label of FIG. 2 is provided with a surface treatment layer 16 on the side opposite to the first pressure-sensitive adhesive layer of the substrate. Typical examples of the surface treatment layer include a printing layer. As the printing layer, a commonly used heat-resistant paint can be used. As the resin component, considering that the label is exposed to a high temperature as high as 450 ° C., silicone resins such as SILRES K, SILRES REN50, Asahi Kasei Wacker Silicone, XIAMETER RSN-0804 RESIN, manufactured by Toray Dow Corning, etc. are preferable. As mentioned. The pigment is preferably resistant to alkali treatment. For example, metal oxides such as iron, nickel, chromium, titanium, and aluminum, alkaline earth metal oxides such as glass, clay, magnesium, calcium, and barium, and complex oxides thereof, silicon dioxide, titanium oxide, zinc white, Examples include mica and other pigments. In order to make printing clear, a white heat resistant paint is preferably used. The printing layer can be formed by dissolving a silicone-based resin, a crosslinking agent used as necessary, and a pigment in a solvent, applying the solution to the surface of the substrate, and drying by heating at 100 to 130 ° C. The solvent is not particularly limited as long as it can dissolve the used resin and the crosslinking agent, and examples thereof include toluene, cyclohexanone, butyl acetate, ethyl acetate, hexane, and methyl ethyl ketone. . As the coating method, any conventionally known method such as a bottom feed reverse coater, a top feed reverse coater, a transfer roll coater, a gravure coater, a fountain die coater, an air knife coater, or a Meyer bar coater can be used. The surface treatment layer usually has a thickness of 5 to 50 μm, preferably 10 to 30 μm.

  The pressure-sensitive adhesive label in which the first and second pressure-sensitive adhesive layers, the release sheet, and the surface treatment layer are laminated on the substrate is punched into a label shape or half-cut in a label shape and supplied as a product. Usually, information is recorded on the label in advance by printing, transferring, or engraving with a laser or the like on the printing layer, and the label is attached to an adherend such as a steel plate. Further, after being attached to the adherend, printing may be performed. The information may be a number such as a production number or a product number, character information, or a barcode.

  In the pressure-sensitive adhesive label of the present invention, the first and second pressure-sensitive adhesive layers and, if necessary, a release sheet and a surface treatment layer may be provided on the substrate, and the production method is not particularly limited. The method generally used when manufacturing the conventional pressure-sensitive adhesive label may be appropriately employed. As a typical manufacturing method, for example, the first and second pressure-sensitive adhesive layers are sequentially applied to the surface opposite to the surface provided with the surface treatment layer of the base material provided with the surface treatment layer, heated and dried, A method of attaching a release sheet, a second and first pressure-sensitive adhesive layers are sequentially applied on a release sheet such as release paper, heated and dried, and then the surface treatment of a substrate provided with a surface treatment layer A method of attaching to the surface opposite to the layer, a first pressure-sensitive adhesive layer formed on the surface of the base material opposite to the surface treatment layer, a second pressure-sensitive adhesive layer formed on the release layer of the release paper, and then the first adhesion Examples include a method of bonding the agent layer and the second adhesive layer.

  The present invention will be described more specifically with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples.

Example 1
First, 200 parts by weight of titanium oxide fine particles and a diluting solvent (toluene) are added to 100 parts by weight of a solid content of silicone resin (SILRES REN50 made by Asahi Kasei Wacker Silicone), kneaded, and then 150 SiO ₂ as a filler. Part by weight was added and mixed and dispersed to obtain a coating solution. This coating solution is applied to one surface of a polyimide substrate having a thickness of 50 μm (Kapton made by Toray DuPont) using a doctor coating machine so that the film thickness after drying becomes 30 μm, followed by heating and drying to form a printing layer. Formed.

  Next, a silicone pressure-sensitive adhesive composition obtained by diluting a silicone-based pressure-sensitive adhesive (SD4570 manufactured by Toray Dow Corning) with toluene is prepared. Further, 100 parts by mass of an acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., SK Dyne 701) is added with isocyanate-based crosslinking. An acrylic pressure-sensitive adhesive composition was prepared by adding 0.4 parts by mass of an agent (manufactured by Nippon Polyurethane Industry, Coronate L). Using the obtained pressure-sensitive adhesive composition, a silicone pressure-sensitive adhesive layer having a thickness of 30 μm after drying by heating (80 to 100 ° C. × 1 to 5 minutes) on the surface opposite to the printing layer of the polyimide base material, An acrylic pressure-sensitive adhesive layer having a thickness of 15 μm after heat drying (100 to 150 ° C. × 1 to 5 minutes) is laminated on the silicone pressure-sensitive adhesive layer, and a release paper is laminated on this layer via a release layer A laminated body was formed. Thereafter, this laminate was cut into an appropriate size to produce an adhesive label.

Example 2
A pressure-sensitive adhesive label was produced in the same manner as in Example 1 except that the thickness of the acrylic pressure-sensitive adhesive layer after drying was changed to 15 μm and 20 μm.

Example 3
A pressure-sensitive adhesive label was produced in the same manner as in Example 1 except that the thickness of the acrylic pressure-sensitive adhesive layer after drying was changed to 15 μm and changed to 25 μm.

Example 4
A pressure-sensitive adhesive label was produced in the same manner as in Example 1 except that the thickness after drying of the silicone-based pressure-sensitive adhesive layer was changed to 30 μm and was 35 μm.

Example 5
As an acrylic pressure-sensitive adhesive composition, 100 parts by weight of an acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., SK Dyne 701), 10 parts by weight of a silicone resin (SILRES K manufactured by Asahi Kasei Wacker Silicone), an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry) Coronate L) An adhesive label was produced in the same manner as in Example 1 except that it was produced by adding 0.4 part by weight.

Comparative Example 1
0.4 parts by weight of an isocyanate-based cross-linking agent (manufactured by Nippon Polyurethane Industry, Coronate L) is added to 100 parts by weight of an acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., SK Dyne 701), and the resulting pressure-sensitive adhesive mixture is carried out. On the opposite surface of the polyimide film printing layer of Example 1 was applied so that the thickness after heating and drying was 30 μm, dried by heating at 80 ° C. for 3 minutes, and then bonded to the release agent-treated surface of the release paper, The obtained laminate was cut into an appropriate size to produce an adhesive label.

Comparative Example 2
10 parts by weight of a silicone resin (SILRES K manufactured by Asahi Kasei Wacker Silicone) and 100 parts by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry, Coronate L) per 100 parts by weight of an acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., SK Dyne 701) The pressure-sensitive adhesive mixture obtained was applied to the opposite side of the polyimide film printing layer of Example 1 so that the thickness after heating and drying was 30 μm, and dried at 80 ° C. for 3 minutes. Then, the adhesive label was produced by sticking on the release agent processing surface of release paper, and cut | disconnecting the obtained laminated body to a suitable magnitude | size.

Comparative Example 3
A silicone pressure-sensitive adhesive (SD4570 manufactured by Toray Dow Corning) was applied to the opposite side of the polyimide film printing layer of Example 1 so that the thickness after heating and drying was 30 μm, and dried by heating at 120 ° C. for 3 minutes. After that, it was bonded to the release agent-treated surface of the release paper, and the resulting laminate was cut into an appropriate size to produce an adhesive label.

Comparative Example 4
A pressure-sensitive adhesive label was produced in the same manner as in Example 1 except that the thickness of the acrylic pressure-sensitive adhesive layer was 10 μm.

Comparative Example 5
A pressure-sensitive adhesive label was produced in the same manner as in Example 1 except that the thickness of the acrylic pressure-sensitive adhesive was 30 μm.

Comparative Example 6
An adhesive label was produced in the same manner as in Example 1 except that the thickness of the silicone adhesive layer was 20 μm.

  For the pressure-sensitive adhesive labels obtained in Examples 1 to 5 and Comparative Examples 1 to 6, an alkali resistance test, a heat resistance test, an alkali resistance, and a heat resistance continuous test were performed by the following methods. The results are shown in Table 1.

<Alkali resistance test (degreasing process test)>
A pressure-sensitive adhesive label from which the release paper was peeled was attached to a steel plate to prepare a test sample. Prepare a 17% aqueous solution of alkali (caustic soda) and heat it to 70 ° C in a water bath, immerse the test sample in it for 20 minutes, take it out, and visually determine whether the label is peeled off, wrinkled, cracked, etc. did. When there was no peeling of a label, a wrinkle, a crack, etc., it evaluated as (circle), and if there existed, it evaluated as x.

<Heat resistance test>
The test sample was heated in an electric furnace at 470 ° C. for 10 minutes and then taken out from the electric furnace, and the presence or absence of peeling, curling or cracking of the label was visually determined. When there was no peeling of a label, a wrinkle, a crack, etc., it evaluated as (circle), and if there existed, it evaluated as x.

<Alkali resistance and heat resistance continuous test>
After the alkali resistance test, the sample was washed with water, acid washed with a 20% aqueous hydrochloric acid solution, further washed with water, and then subjected to the heat resistance test. After taking out from the electric furnace, the presence or absence of peeling, wrinkling, cracking or the like of the label was visually determined. When there was no peeling of a label, a wrinkle, a crack, etc., it evaluated as (circle), and if there existed, it evaluated as x.

  From Table 1, none of the pressure-sensitive adhesive labels of the examples were peeled off, kneaded or cracked in any of the alkali resistance test, heat resistance test, and continuous test, and had excellent heat resistance and alkali resistance. I understand that. On the other hand, peeling of the adhesive labels of Comparative Examples 3 and 4 was observed in the alkali resistance test. In addition, the adhesive labels of Comparative Examples 1, 5, and 6 are all observed to be peeled off in the heat resistance test, and in the continuous test, all of the Comparative Examples are observed to be peeled off, which indicates that there is a problem.

1,11 Heat-resistant, alkali-resistant adhesive label 2,12 Base material 3,13 First adhesive layer (silicone-based adhesive layer)
4, 14 Second adhesive layer (acrylic adhesive layer)
15 Release sheet 16 Surface treatment layer

Claims (6)

  A first pressure-sensitive adhesive layer made of a silicone-based pressure-sensitive adhesive and a second pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive are laminated on the first pressure-sensitive adhesive layer, and the thickness of the first pressure-sensitive adhesive layer Is a heat- and alkali-resistant pressure-sensitive adhesive label, wherein the thickness of the second pressure-sensitive adhesive layer is more than 10 μm and less than 30 μm.   The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to claim 1, wherein the first pressure-sensitive adhesive layer has a thickness of 30 µm or more, and the second pressure-sensitive adhesive layer has a thickness of 15 to 25 µm.   The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to claim 1 or 2, wherein the second pressure-sensitive adhesive layer further contains a silicone resin.   The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to claim 1, further comprising a release sheet on the second pressure-sensitive adhesive layer.   The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to any one of claims 1 to 4, further comprising a surface treatment layer on a side opposite to the first pressure-sensitive adhesive layer of the substrate.   The heat-resistant and alkali-resistant pressure-sensitive adhesive label according to claim 5, wherein the surface treatment layer is a printing layer.

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