JP5595398B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to an adhesive sheet having an adhesive layer on a substrate. This application claims priority based on Japanese Patent Application No. 2009-171886, filed on Jul. 23, 2009, the entire contents of which are incorporated herein by reference.

  An adhesive sheet having an adhesive layer on one side or both sides of a sheet-like substrate is widely used in various fields such as packaging, bonding, surface protection, masking, labeling, marking, and cleaning. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer can be classified by the type of base polymer (the main component of the polymer component, that is, the component occupying 50% by mass or more). The adhesive may be appropriately selected from various pressure-sensitive adhesives such as a pressure-sensitive adhesive having a polymer as a base polymer), an acrylic pressure-sensitive adhesive, a vinyl pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive. Moreover, the base material of the said adhesive sheet can be suitably selected from various sheet | seat materials, such as paper, cloth, a plastic film, metal foil, these composites, a laminated body, according to a use and the objective. As technical literature regarding the pressure-sensitive adhesive sheet, for example, Patent Literatures 1 to 3 are cited.

Japanese Patent Application Publication No. 2001-31922 Japanese Utility Model Registration No. 2521127 Japanese Patent Application Publication No. 2007-117534

  However, depending on the combination of the base material and the pressure-sensitive adhesive constituting the pressure-sensitive adhesive sheet, the quality of the pressure-sensitive adhesive sheet may be greatly deteriorated due to aging or heat. More specifically, for example, in a pressure-sensitive adhesive sheet in which a rubber-based pressure-sensitive adhesive layer is provided on a polyolefin film (typically a polyethylene film) as a base material, due to aging or heat, the adhesive performance is reduced (for example, There have been cases in which at least one event such as a significant decrease in adhesive strength and a decrease in appearance quality (for example, a wound nest occurs in a roll-shaped adhesive sheet) occurs. Polyolefin is a material having a preferable characteristic that it has low environmental burden and excellent recyclability among resin materials. However, due to the above circumstances, it is necessary to be careful when using it as a base material for a pressure-sensitive adhesive sheet having a rubber-based pressure-sensitive adhesive layer. It was a thing.

  The present invention relates to a pressure-sensitive adhesive sheet having a rubber-based pressure-sensitive adhesive layer provided on a base material, which uses a polyolefin as a constituent component of a resin material constituting the base material and has excellent quality stability. The purpose is to provide.

  The present inventor has found that a low-molecular-weight component (process oil, a relatively large amount of a general rubber-based pressure-sensitive adhesive) causes a decrease in quality in a pressure-sensitive adhesive sheet having a structure in which a rubber-based pressure-sensitive adhesive layer is provided on a polyolefin film. It was thought that a part of the tackifying resin or the like) was caused by the transfer from the pressure-sensitive adhesive layer to the base material (here, the polyolefin film). When a part of the pressure-sensitive adhesive component moves to the base material and is lost from the pressure-sensitive adhesive layer, the composition of the pressure-sensitive adhesive is different from the original component ratio, which reduces the pressure-sensitive adhesive properties (for example, pressure-sensitive adhesive force). Can be a factor. Moreover, the low molecular weight component transferred to the base material causes the base material to swell, and the swelling can be manifested as a change in the size of the base material. Such a dimensional change can be a factor that causes a decrease in the appearance quality of the pressure-sensitive adhesive sheet (such as generation of a wound web). Therefore, the present inventor has examined various materials in which the constituent components of the rubber-based pressure-sensitive adhesive layer are difficult to migrate among resin materials containing polyolefin. As a result, the present inventors have found that a resin material containing polylactic acid at a predetermined mass ratio is suitable.

  That is, the pressure-sensitive adhesive sheet disclosed herein includes a sheet-like base material and a pressure-sensitive adhesive layer provided on at least one surface of the base material. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is a rubber-based pressure-sensitive adhesive having a rubber-based polymer as a base polymer. And the surface part of the location in which the said adhesive layer is provided at least among the said base materials is formed with the resin material which has polyolefin (for example, polyethylene) and polylactic acid as a main. The degree of biomass of the resin material is about 35% or more and less than 100%.

  As for the base material which comprises the said adhesive sheet, the resin material which comprises the surface part which touches a rubber-type adhesive layer at least is a resin material which has polyolefin and polylactic acid as a main component. Thus, by setting it as the resin composition containing polylactic acid in addition to polyolefin, it can suppress that the structural component of a rubber-type adhesive layer transfers to a base material, and can maintain the quality of an adhesive sheet stably. . Moreover, since polylactic acid can be synthesized from plant-derived materials, there is also an advantage that the amount of petroleum used can be reduced according to the base material having the above-described configuration. The degree of biomass of the resin material is preferably about 35% or more and less than 100%. Thereby, compared with the base material (for example, polyolefin film) which does not contain polylactic acid, and the base material whose biomass degree is too low than the said range, stability of adhesive performance (for example, adhesive force) can be improved significantly.

  Here, the resin material “mainly composed of polyolefin and polylactic acid” means that the proportion of the total mass of polyolefin and polylactic acid in the mass of the polymer component contained in the resin material is 50% or more. Say. The ratio of the total mass of polyolefin and polylactic acid to 50% or more of the total mass of the resin material is one typical example of a resin material mainly composed of polyolefin and polylactic acid. In the present specification, the degree of biomass refers to the ratio of the mass of polylactic acid (polylactic acid content) to the mass of the resin material as a whole (in other words, the mass of the base material).

  In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, the resin material has a mass of the polylactic acid in a total mass of the polyolefin and the polylactic acid of about 40% to 80%. According to the base material having the biomass degree in the above range, the size change of the base material due to the provision of the rubber-based pressure-sensitive adhesive layer can be highly suppressed.

  The technology disclosed here can be preferably applied to, for example, a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer composed of a rubber-based pressure-sensitive adhesive having a styrene-isoprene-styrene block copolymer (SIS) as a base polymer.

  According to this specification, an adhesive sheet roll formed by winding any of the adhesive sheets disclosed herein into a roll is provided. Compared with a resin material having a composition containing a polyolefin (for example, polyethylene) alone as a polymer component, a resin material having a composition containing polylactic acid in addition to a polyolefin can form a stronger sheet material. In general, polylactic acid has a hard and brittle nature, and according to a resin material having a composition containing olefin in addition to polylactic acid, the above-mentioned hardness and brittleness are improved (more supple). The elasticity of the sheet material can be improved. Thus, the sheet material (base material) having both moderate stiffness (tension) and flexibility is suitable for forming a roll-shaped pressure-sensitive adhesive sheet (that is, pressure-sensitive adhesive sheet roll). For example, the handleability at the time of manufacture and use of the pressure-sensitive adhesive sheet roll is good.

  As a preferable embodiment of the pressure-sensitive adhesive sheet roll disclosed herein, the pressure-sensitive adhesive sheet is wound in a roll shape in a direction having a pressure-sensitive adhesive layer on at least the outer surface of the substrate, and is exposed to the outermost periphery. Examples thereof include an adhesive sheet roll that is used by rolling on the surface to be processed while pressing the layer against the surface to be processed. In the pressure-sensitive adhesive sheet roll used by rolling while applying a stress in the radial direction of the roll as described above, the significance of using a base material that combines moderate stiffness and flexibility can be exhibited particularly well.

FIG. 1 is a cross-sectional view schematically showing a configuration example of an adhesive sheet according to the present invention. FIG. 2 is a cross-sectional view schematically showing another configuration example of the pressure-sensitive adhesive sheet according to the present invention. FIG. 3 is a cross-sectional view schematically showing another configuration example of the pressure-sensitive adhesive sheet according to the present invention. FIG. 4 is a cross-sectional view schematically showing another configuration example of the pressure-sensitive adhesive sheet according to the present invention. FIG. 5 is an explanatory view illustrating a typical usage mode of the pressure-sensitive adhesive sheet roll. FIG. 6 is an explanatory view illustrating a typical usage mode of the pressure-sensitive adhesive sheet roll.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The pressure-sensitive adhesive sheet provided by the present invention has a rubber-based pressure-sensitive adhesive layer on at least one surface of a substrate. It may be a single-sided pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer on only one surface of the substrate (support), and is a double-sided pressure-sensitive adhesive sheet having the above-mentioned pressure-sensitive adhesive layer on both surfaces of the substrate. Also good. The concept of the pressure-sensitive adhesive sheet herein may include what are called pressure-sensitive adhesive tapes, pressure-sensitive adhesive labels, pressure-sensitive adhesive films and the like. The pressure-sensitive adhesive layer is typically formed continuously, but is not limited to such a form. For example, the pressure-sensitive adhesive layer is formed in a regular or random pattern such as a dot shape or a stripe shape. It may be. The pressure-sensitive adhesive sheet provided by the present invention may be in the form of a roll or a single sheet. Or the adhesive sheet of the form processed into various shapes may be sufficient.

  The pressure-sensitive adhesive sheet disclosed herein may have, for example, a cross-sectional structure schematically shown in FIGS. Among these, FIG. 1, FIG. 2 is an example of a structure of a double-sided adhesive type adhesive sheet. In the pressure-sensitive adhesive sheet 1 shown in FIG. 1, pressure-sensitive adhesive layers 21 and 22 are provided on both surfaces (both non-peelable) of a base material 10, and at least the pressure-sensitive adhesive layer side is a release surface. The release liners 31 and 32 are protected by the release liners 31 and 32, respectively. In the pressure-sensitive adhesive sheet 2 shown in FIG. 2, pressure-sensitive adhesive layers 21 and 22 are provided on both surfaces (both non-peelable) of the base material 10, and one of the pressure-sensitive adhesive layers 21 is a release surface on both surfaces. It has a configuration protected by the release liner 31. This type of pressure-sensitive adhesive sheet 2 has a configuration in which the pressure-sensitive adhesive layer 22 is also protected by the release liner 31 by winding the pressure-sensitive adhesive sheet and bringing the other pressure-sensitive adhesive layer 22 into contact with the back surface of the release liner 31. be able to.

  3 and 4 are configuration examples of a single-sided adhesive type adhesive sheet. The pressure-sensitive adhesive sheet 5 shown in FIG. 3 is provided with a pressure-sensitive adhesive layer 21 on one surface 10A (non-peelable) of the substrate 10, and at least the surface (adhesive surface) 21A of the pressure-sensitive adhesive layer 21 is peeled off at least on the pressure-sensitive adhesive layer side. It has the structure protected with the release liner 31 used as the surface. The pressure-sensitive adhesive sheet 6 shown in FIG. 4 has a configuration in which a pressure-sensitive adhesive layer 21 is provided on one surface 10A (non-peelable) of the substrate 10. The other surface 10B of the base material 10 is a release surface. When the pressure-sensitive adhesive sheet 6 is wound, the pressure-sensitive adhesive layer 21 comes into contact with the other surface 10B, and the surface (adhesive surface) 21B of the pressure-sensitive adhesive layer is the base material. It is protected by the other surface 10B.

  In the technology disclosed herein, a resin material mainly composed of polyolefin and polylactic acid (hereinafter also referred to as “PO / PLA resin material”) is used as a constituent material of the base material. It suffices that at least the surface portion of the base material where the rubber-based pressure-sensitive adhesive layer is provided is made of the resin material. For example, when a pressure-sensitive adhesive layer is provided on one surface of the base material, a base material having a structure in which only the surface portion of the one surface is made of the resin material can be used. The base material having such a structure includes a layer made of a PO / PLA resin material and a layer made of another material (for example, a layer made of a resin material such as polyolefin, paper, cloth, metal foil, etc.). The base material of the laminated structure is illustrated. In a preferred embodiment, the entire substrate is made of a PO / PLA resin material. A base material having such a structure is preferable because the productivity is good and the base material hardly warps even if the temperature and humidity change. For example, a substrate formed by molding a PO / PLA resin material into a sheet can be preferably used. Further, from the viewpoint of recyclability, a substrate made entirely of PO / PLA resin material or a substrate made entirely of PO / PLA resin material and other resin materials is preferable.

  The polyolefin in the PO / PLA resin material is a polymer having α-olefin as a main monomer (main component among monomer components). Specific examples of the polyolefin include those having ethylene as a main monomer (polyethylene), those having propylene as a main monomer (polypropylene), and the like. The polyethylene may be a homopolymer of ethylene, and is a copolymer of ethylene and another olefin (for example, one or more selected from α-olefins having 3 to 10 carbon atoms). It may be a combination of ethylene and a monomer other than olefin (for example, one or more selected from ethylenically unsaturated monomers such as vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate). It may be a polymer. The polypropylene may be a homopolymer of propylene, and is composed of propylene and another olefin (for example, one or more selected from α-olefins having 2 to 4 to 10 carbon atoms). A copolymer may be sufficient and the copolymer of monomers other than a propylene and an olefin may be sufficient. The PO / PLA resin material in the technology disclosed herein may contain only one kind of polyolefin, or may contain two or more kinds of polyolefin.

  In a preferred embodiment, the polyolefin in the PO / PLA resin material is polyethylene. As the polyethylene (PE), any of so-called low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and the like can be used. One of these (for example, LDPE) may be included alone, or two or more may be included in an appropriate combination.

  As polylactic acid in the PO / PLA resin material, L-lactic acid homopolymer (poly-L-lactic acid), D-lactic acid homopolymer (poly-D-lactic acid), L-form and D-form are arbitrary. Any of a random copolymer copolymerized at a ratio, a block copolymer of L-form and D-form, and the like can be used. One of these may be included alone, or two or more (for example, poly-L-lactic acid and poly-D-lactic acid) may be included in an appropriate combination. In the technology disclosed herein, the polylactic acid used for the preparation of the PO / PLA resin material can be blended with other materials in the form of a polylactic acid-containing resin containing polylactic acid in any proportion. As the polylactic acid-containing resin, a resin in which about 50% by mass or more (more preferably 70% by mass or more, more preferably 90% by mass or more, for example, 95% by mass or more) of the polymer component contained in the resin is polylactic acid. (Polylactic acid resin) can be preferably used. The proportion of polylactic acid contained in the polylactic acid-containing resin can be generally grasped as being consistent with the biomass degree of the resin.

  The PO / PLA resin material in the technology disclosed herein preferably has a biomass degree of about 35% or more and less than 100% (for example, about 40% or more and 80% or less). According to the pressure-sensitive adhesive sheet having a rubber-based pressure-sensitive adhesive layer provided on the surface of the base material having such a composition, the pressure-sensitive adhesive performance (for example, the base material not containing polylactic acid or the biomass degree is too low than the above range) The stability of the adhesive strength can be greatly increased. For example, a pressure-sensitive adhesive sheet can be realized in which the rate of change in adhesive strength before and after storage at 50 ° C. for 7 days is within ± 15%. Moreover, compared with the case where a biomass degree is 0%, the adhesive sheet by which the change rate of the adhesive force before and behind preserve | saving for 7 days at 50 degreeC was suppressed to half or less can be implement | achieved.

  In a preferred embodiment of the technology disclosed herein, the biomass degree of the PO / PLA resin material is about 40% or more and less than 100% (more preferably about 45% or more and less than 100%). By setting the degree of biomass in the above range, the size change of the base material due to the provision of the rubber-based pressure-sensitive adhesive layer can be suppressed to a higher degree. This is particularly significant in a pressure-sensitive adhesive sheet having a structure in which a region where a pressure-sensitive adhesive layer is provided and a region where a pressure-sensitive adhesive layer is not provided exist on one surface and / or the other surface of the substrate surface. In the pressure-sensitive adhesive sheet having such a configuration, if the degree of change in the size of the base material is different between the region where the pressure-sensitive adhesive layer is provided and the region where the pressure-sensitive adhesive layer is not provided, wrinkles and twists may occur in the pressure-sensitive adhesive sheet, and the appearance quality may deteriorate It is. It is particularly significant in a single-sided pressure-sensitive adhesive sheet that the size change of the base material due to the provision of the pressure-sensitive adhesive layer can be suppressed to a higher degree. This is because the pressure-sensitive adhesive sheet having such a configuration warps the pressure-sensitive adhesive sheet when the degree of change in size of the substrate is different between the surface on the pressure-sensitive adhesive layer side and the opposite surface, thereby reducing usability and appearance quality.

  In a preferred embodiment of the technology disclosed herein, the entire base material is formed of a PO / PLA resin material. The biomass degree of the PO / PLA resin material can be, for example, about 35% or more and less than 100% (preferably about 40% or more and less than 100%). More preferably, the degree of biomass is about 40% to 80% (for example, about 40% to 70%). By setting the biomass degree within the above range, the PE laminated paper has a thickness comparable to that of PE laminated paper, which is a kind of base material widely used in the past (for example, ± 10% thickness of PE laminated paper). Substrates can be realized that exhibit relatively firm stiffness (eg, ± 50% stiffness of PE laminated paper). The pressure-sensitive adhesive sheet having such a base material is preferable because it can be preferably employed as a substitute for the PE laminated paper in the field where PE laminated paper has been used as the base material.

  In addition, the firm strength of the said base material can be measured with the following method. That is, a strip-shaped sample having a width of 20 mm and a length of 64 mm is rounded to form a ring having a diameter of 20 mm and a width of 20 mm. The maximum strength when the ring is crushed in the radial direction from a circle to a plane at a speed of 10 mm / min is defined as the stiffness of the sample. In the base material manufactured by the extrusion molding method, it is preferable to prepare the sample so that the MD (flow direction) of the base material substantially matches the length direction of the sample.

  The PO / PLA resin material in the technology disclosed herein can contain other polymers as optional components in addition to the polyolefin and polylactic acid. Such a polymer may be one or more selected from thermoplastic resins that can be molded together with polyolefin and polylactic acid. In a preferred embodiment, the total mass of polyolefin and polylactic acid in the PO / PLA resin material is about 75% or more (for example, about 85% or more). The total mass of polyolefin and polylactic acid may be approximately 90% or more of the PO / PLA resin material, or may be substantially 100%.

  The PO / PLA resin material can contain a compatibilizing agent that improves the compatibility between polyolefin and polylactic acid, if necessary. As this compatibilizing agent, known or commonly used ones can be appropriately selected and used. Specifically, for example, a block or graft copolymer of a polyolefin and a polylactic acid resin, a block or graft copolymer of a polyolefin and an acrylic resin, a polyolefin modified with a functional group having reactivity with polylactic acid, A styrene-ethylene / butylene-crystalline polyolefin block copolymer (SEBC) modified with such a functional group can be used. As commercially available products, functional group-modified SEBC (manufactured by JSR Corporation, trade name “XDH-0612”), ethylene-glycidyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name “Bond First E”), etc. should be used. Can do. The amount of the compatibilizer used can be, for example, about 3 to 15 parts by mass (typically about 5 to 10 parts by mass) with respect to 100 parts by mass of the total amount of polyolefin and polylactic acid. In addition, a compatibilizing agent may be mix | blended so that a transparent PO / PLA resin material may be obtained, or may be mix | blended so that a cloudy PO / PLA resin material may be obtained. The white turbid PO / PLA resin material can be formed into a sheet (for example, extrusion molding) to form a base material having a texture similar to paper. Such a textured base material is preferable because it can give a good impression to the user of the pressure-sensitive adhesive sheet. In particular, in the pressure-sensitive adhesive sheet roll (for example, pressure-sensitive adhesive sheet roll used for cleaning the floor surface, etc.) that is used by rolling the pressure-sensitive adhesive layer exposed on the outermost periphery against the surface to be processed, the user can Since there is a strong tendency to prefer a textured substrate similar to paper, it is advantageous to be able to form a moderately cloudy substrate.

  Other PO / PLA resin materials include fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, lubricants, plasticizers, and colorants. Various additives such as (pigments, dyes, etc.) may be blended.

  The thickness of the base material can be, for example, about 5 μm to 500 μm (preferably about 10 μm to 200 μm). In the pressure-sensitive adhesive sheet roll used by rolling the pressure-sensitive adhesive layer exposed on the outermost surface against the surface to be processed (for example, a pressure-sensitive adhesive sheet roll used for cleaning the floor surface, etc.), It is appropriate that the thickness is about 30 μm to 300 μm (typically about 50 to 100 μm).

  In manufacturing the base material having such a configuration, various conventionally known sheet material manufacturing methods can be applied. For example, a base material made entirely of PO / PLA resin material is a resin material component (polyolefin and polylactic acid, as well as other polymers and compatibilizers and other additives used as necessary) in the extruder. It can be molded by charging, melting and kneading, and extruding the kneaded material from the die of the extruder into a film and cooling.

  The surface of the substrate (particularly the surface on the side where the pressure-sensitive adhesive layer is provided) may be subjected to known or conventional surface treatments such as corona discharge treatment, plasma treatment, and application of a primer. Such a surface treatment can be, for example, a treatment for enhancing the substrate anchoring property of the pressure-sensitive adhesive layer. Moreover, in the single-sided adhesive type adhesive sheet, the peeling process for providing peelability may be given to the back surface (surface on the opposite side to the surface in which an adhesive layer is provided) of the base material. Such a release treatment can be performed using a known or commonly used release treatment agent (for example, a silicone-based, fluorine-based, long-chain alkyl-based release treatment agent).

  In the technology disclosed herein, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is a rubber-based pressure-sensitive adhesive having a rubber-based polymer as a base polymer (a main component among polymer components). As such rubber-based pressure-sensitive adhesive, those known or commonly used in the field of pressure-sensitive adhesive sheets can be appropriately selected and used. Such a pressure-sensitive adhesive typically contains, as main components, a rubber-based polymer, a tackifier resin (tackifier), and a process oil (softener).

  Examples of the base polymer include natural rubber, styrene butadiene rubber (SBR), polyisobutylene, polyisoprene, styrene-isoprene-styrene block copolymer (SIS), and styrene-butadiene-styrene block copolymer (SBS). The rubber-based polymer. It may be a pressure-sensitive adhesive containing one of these rubber-based polymers alone, or a pressure-sensitive adhesive containing two or more rubber-based polymers in an appropriate combination. In a preferred embodiment, the rubber-based pressure-sensitive adhesive is a pressure-sensitive adhesive (SIS-based pressure-sensitive adhesive) having SIS as a base polymer.

  As the tackifying resin, various rosin-based, terpene-based, hydrocarbon-based, epoxy-based, polyamide-based, elastomer-based, phenol-based, ketone-based, and the like can be used alone or in combination of two or more. Can be used in combination. The compounding amount of the tackifying resin with respect to 100 parts by mass of the base polymer can be about 50 to 200 parts by mass, for example.

  Moreover, as said process oil, process oils, such as general paraffin type, a naphthene type, and an aromatic type, can be used individually or in combination of 2 or more types. Although it does not specifically limit, the compounding quantity of the process oil with respect to 100 mass parts of base polymers can be about 50-200 mass parts, for example.

  The pressure-sensitive adhesive may contain a polymer other than rubber-based polymer (for example, acrylic polymer, vinyl polymer, etc.) as a secondary polymer component as necessary. The content of these secondary polymer components is usually 50 parts by mass or less with respect to 100 parts by mass of the base polymer, and typically 20 parts by mass or less. As a preferred example of the pressure-sensitive adhesive disclosed herein, a pressure-sensitive adhesive substantially free of such secondary polymer component can be mentioned.

  In the technology disclosed herein, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer further includes a filler (inorganic filler, organic filler, etc.), an anti-aging agent, an antioxidant, an ultraviolet absorber, a light stabilizer, Various additives such as antistatic agents, lubricants, colorants (pigments, dyes, etc.) may be blended. The types and blending amounts of these additives can be the same as the usual types and blending amounts in this type of pressure-sensitive adhesive.

  The rubber-based adhesive is a hot-melt type in which an adhesive component is heated and melted to form an adhesive layer, an emulsion type in which an aqueous dispersion of the adhesive component is dried to form an adhesive layer, and an organic solvent solution of the adhesive component. It may be various types of pressure-sensitive adhesives such as a solvent type which is dried to form a pressure-sensitive adhesive layer. Of these, a hot-melt adhesive is preferable.

  The thickness of the pressure-sensitive adhesive layer can be, for example, about 2 μm to 200 μm (preferably about 5 μm to 100 μm). In the pressure-sensitive adhesive sheet roll (for example, pressure-sensitive adhesive sheet roll used for cleaning the floor surface, etc.) used by rolling the pressure-sensitive adhesive layer exposed on the outermost periphery against the surface to be processed, usually the pressure-sensitive adhesive layer The thickness is preferably in the range of about 5 μm to 50 μm, typically about 10 μm to 30 μm, for example, about 10 μm to 20 μm.

  In the pressure-sensitive adhesive sheet disclosed herein, the rubber-based pressure-sensitive adhesive layer may be provided only on one surface of the base material, or may be provided on each of the one surface and the other surface of the base material. In addition, a rubber-based pressure-sensitive adhesive layer is provided on one surface of the substrate, and a pressure-sensitive adhesive other than rubber-based (a pressure-sensitive adhesive having a polymer other than a rubber-based polymer as a base polymer. For example, an acrylic pressure-sensitive adhesive , A non-rubber pressure-sensitive adhesive such as a vinyl pressure-sensitive adhesive or a silicone pressure-sensitive adhesive) may be provided. In addition, the rubber-based pressure-sensitive adhesive layer and the non-rubber-based pressure-sensitive adhesive layer may be provided on the same side surface of the base material with different ranges, or may be stacked on the rubber-based pressure-sensitive adhesive layer. A rubber-based pressure-sensitive adhesive layer may be provided. In short, a rubber-based pressure-sensitive adhesive is applied on at least a part of the surface of the base material, and at least the surface portion of the base material under the rubber-based pressure-sensitive adhesive is made of a PO / PLA resin material.

  The rubber-based pressure-sensitive adhesive layer may be provided in the entire range of one side and / or the other side, or may be provided only in a partial region. The technique disclosed here is, for example, that the shape of the base material is long, and the region where the adhesive layer is not formed is left in one end or the other end in the longitudinal direction, and the other portions Can be preferably applied to the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is continuously (solid-coated). As another preferable application object, an adhesive sheet in an embodiment in which the adhesive layer is provided in a stripe shape is exemplified. In the pressure-sensitive adhesive sheet having such a configuration, the significance of suppressing the change in size of the base material due to the provision of the pressure-sensitive adhesive layer is particularly great.

Hereinafter, an embodiment in which the technology disclosed herein is applied to an adhesive sheet roll will be described with reference to the drawings.
5 and 6 are schematic views showing typical usage states of the pressure-sensitive adhesive sheet roll 60 according to one embodiment of the present invention. The pressure-sensitive adhesive sheet roll 60 includes a pressure-sensitive adhesive sheet 62 having a pressure-sensitive adhesive layer 82 formed on one surface of a base material 70 formed by forming a PO / PLA resin material into a long sheet shape (band shape). Is wound around the core 64 in a roll shape so that is directed to the outer side (the outer peripheral side of the roll). The width of the base material 70 is usually about 2 cm to 50 cm (for example, about 5 to 30 cm). As the winding core 64, a cushion-made paper (typically made of cardboard) can be preferably used. Alternatively, it may be a core made of another material (for example, synthetic resin). Moreover, what is called a coreless type adhesive sheet roll formed by winding only the adhesive sheet 62 in a roll shape without using the winding core 64 may be used.

  The adhesive sheet 62 is provided with cuts (not shown) for cutting almost every circumference of the adhesive sheet roll 60. This cut is a cutting means used to make it easy to cut one end of the adhesive sheet 62 in the longitudinal direction from the remaining portion. For example, the slit is formed by arranging long holes or corrugated slits, intermittent slits such as perforations, etc. It can be. In a preferred embodiment, the cut is provided so as to cross the adhesive sheet 62 in the width direction (direction perpendicular to the longitudinal direction). Alternatively, it may be a cut provided so as to extend from one end of the width of the pressure-sensitive adhesive sheet 62 halfway to give an opportunity for cutting.

  The pressure-sensitive adhesive layer 82 is made of a rubber-based pressure-sensitive adhesive, and in this embodiment, is made of a pressure-sensitive adhesive (SIS-based pressure-sensitive adhesive) having SIS as a base polymer. As the SIS pressure-sensitive adhesive, those similar to those known or commonly used in this technical field can be preferably used. On one surface (outer surface) of the substrate 70, the pressure-sensitive adhesive layer 82 may be formed in the entire range, or the pressure-sensitive adhesive layer 82 may be formed in a range excluding a part thereof. In this embodiment, as shown in FIG. 5, non-adhesive portions (dry edges) 72 and 73 where the adhesive layer 82 is not formed are provided along both ends of the base material 70 in the width direction. The widths of the non-adhesive portions 72 and 73 can be about 2 mm to 10 mm, for example. An adhesive layer 82 is formed in a stripe shape along the longitudinal direction of the base material in the width central portion excluding the non-adhesive portions 72 and 73. The width of each pressure-sensitive adhesive layer 82 forming the stripe can be, for example, about 0.5 mm to 3 mm. The pitch of the pressure-sensitive adhesive layer 82 can be set to, for example, about 1 mm to 4 mm.

  As shown in FIGS. 5 and 6, the adhesive sheet roll 60 is used by being mounted on a jig 90 that rotatably holds the adhesive sheet roll 60. The jig 90 has a rotating portion 92 that is inserted into the central portion of the pressure-sensitive adhesive sheet roll 60 (for example, the hollow portion of the winding core 64), and a handle 93 that extends substantially perpendicular to the rotation axis of the rotating portion 92. . The tip of the handle 93 is a grip portion 94. A user (not shown) grasps the grip 94 and presses the outer periphery of the pressure-sensitive adhesive sheet roll 60 with a pressing force of about 300 g to 2000 g (typically mainly about 500 g to 1000 g). Surface) by rolling while pressing against the surface 96, foreign matter (dust etc.) on the surface to be treated is captured by the adhesive layer 82.

  Here, the pressure-sensitive adhesive sheet roll 60 exhibits moderate cushioning properties in the radial direction of the roll due to the characteristics of the core 64 and the pressure-sensitive adhesive layer 82 being provided in a stripe shape. This is advantageous in that the outer shape of the pressure-sensitive adhesive sheet roll 60 can be deformed to some extent along the surface shape of the surface to be processed 96. However, if the material of the base material 70 is hard and brittle, an unexpected crack may occur in the base material 70 due to the above deformation. In this regard, in the present embodiment, since the PO / PLA resin material having moderate stiffness and flexibility is used as the constituent material of the base material 70, the present invention can be applied without any inconvenience.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to the specific examples. In the following description, “part” and “%” are based on mass unless otherwise specified.

<Example 1: Preparation of adhesive sheet sample>
Substrate sample 1:
LDPE (trade name “Sumikasen F-208-3” from Sumitomo Chemical Co., Ltd. was used. The same applies hereinafter.) 100 parts were used for a twin screw extruder (Technobel Co., Ltd., model number “KZW-15.” The same applies hereinafter. ) And melted by heating, extruded under conditions of a temperature of about 200 ° C. and a pressure of about 5 to 10 MPa, and formed into a film having a thickness of 60 μm to 80 μm. Thereby, the base material sample 1 which a polymer component substantially consists of LDPE (biomass degree 0.0%) was obtained.

Substrate sample 2:
75 parts of LDPE and 20 parts of polylactic acid resin (trade name “TERRAMAC (Teramac) TP4000-CN” (biomass degree 98.0%) of Unitika Co., Ltd. are the same in Samples 3 to 10 and Sample 12). And 5 parts of functional group-modified SEBC (trade name “XDH-0612” manufactured by JSR Corporation) as a compatibilizing agent were put into a twin screw extruder and kneaded and extruded in the same manner as in Example 1. To form a film. As a result, a base material sample 2 having a polymer component substantially composed of LDPE and polylactic acid and having a biomass degree of 19.6% was obtained.

Substrate sample 3:
It contains LDPE and polylactic acid as polymer components, except that the blending ratio (usage ratio) of LDPE and polylactic acid resin is changed from 75:20 to 55:40. A substrate sample 3 of 2% was obtained.

Substrate sample 4:
A group in which the polymer component is substantially composed of LDPE and polylactic acid, and the biomass degree is 44.1%, except that the amount ratio of LDPE and polylactic acid resin is changed to 50:45. A material sample 4 was obtained.

Substrate sample 5:
It contains LDPE and polylactic acid as polymer components, and has a biomass degree of 46.6%, except that the amount ratio of LDPE and polylactic acid resin is changed to 47.5: 47.5. A substrate sample 5 was obtained.

Base material sample 6:
Base material sample 6 containing LDPE and polylactic acid as polymer components and having a biomass degree of 49.0% except that the amount ratio of LDPE and polylactic acid resin was changed to 45:50. Got.

Substrate sample 7:
Base material sample 7 containing LDPE and polylactic acid as polymer components and having a biomass degree of 53.9% except that the amount ratio of LDPE and polylactic acid resin was changed to 40:55. Got.

Base material sample 8:
Base material sample 8 containing LDPE and polylactic acid as polymer components and having a degree of biomass of 58.8%, except that the amount ratio of LDPE and polylactic acid resin was changed to 35:60. Got.

Substrate sample 9:
Substrate sample 9 containing LDPE and polylactic acid as polymer components and having a biomass degree of 78.4%, except that the amount of LDPE and polylactic acid resin used was changed to 15:80. Got.

Substrate sample 10:
100 parts of polylactic acid was put into a twin-screw extruder and melted by heating, and extruded under conditions of a temperature of about 200 ° C. and a pressure of about 5 to 10 MPa to form a film having a thickness of 60 μm to 80 μm. As a result, a base material sample 10 having a biomass degree of 98.0% was obtained.

Substrate sample 11:
For control, a base material (PE laminated paper with a total thickness of 70 μm) in which a polyethylene film with a thickness of 20 μm was laminated on one side of a pure white paper with a thickness of 50 μm was prepared.

Adhesive sheet samples 1-11:
By applying a hot melt type adhesive in a heated and melted state on one surface of the substrate samples 1 to 11 (in the substrate sample 11, the surface opposite to the surface on which the polyethylene film is laminated), A uniform pressure-sensitive adhesive layer having a thickness of about 20 μm was formed. As a pressure-sensitive adhesive, SIS (trade name “Quintac 3433N” of ZEON CORPORATION) is used as a base polymer, 100 parts of the base polymer, and 100 parts of tackifier resin (trade name “Escollet 1310” of Tonen Chemical Co., Ltd.). And SIS adhesive (hereinafter referred to as adhesive A-1) consisting of 60 parts of process oil (trade name “Knife Rex 222B” from Japan Chemtech Co., Ltd.). Thus, the adhesive sheet samples 1-11 corresponding to each base material sample were produced.

<Example 2: Evaluation of adhesive force change rate>
Initial adhesive strength:
Each pressure-sensitive adhesive sheet sample prepared above was held for 1 day in an environment of 23 ° C. and RH 50%. Thereafter, two strip-shaped test pieces each having a width of 25 mm were cut out from each adhesive sheet sample (that is, n = 2), and a 2 kg roller was reciprocated once and pressed onto a stainless steel (SUS: BA304) plate. After holding this at 23 ° C. for 30 minutes, using a tensile tester, in accordance with JIS Z 0237, peeling off 180 ° at a temperature of 23 ° C. and a measurement environment of RH 50% under conditions of a tensile speed of 300 mm / min. The force (initial adhesive force F1) was measured.

Adhesive strength after time:
Each pressure-sensitive adhesive sheet sample prepared above was held in a dryer at 50 ° C. for 7 days. Thereafter, two strip-shaped test pieces having a width of 25 mm were cut out from each pressure-sensitive adhesive sheet sample (sample after aging) (that is, n = 2). Using these test pieces, the 180 ° peel adhesive strength (adhesive strength F2 after time) was measured in the same manner as the initial adhesive strength.

Adhesive strength change rate:
For each adhesive sheet sample, the initial adhesive force F1 and the post-aging adhesive force F2 obtained above were substituted into the following formula: (F2-F1) / F1 × 100; to determine the adhesive force change rate (%). .

  Table 1 shows the initial adhesive strength, the post-aging adhesive strength, and the adhesive force change rate of the adhesive sheet samples 1 to 10 together with the schematic configuration of each adhesive sheet sample. In addition, the symbol # attached to the back of the numerical value in the adhesive strength after the lapse of time of the sample 10 indicates that the sample broke the substrate at the time of measurement. Therefore, it is presumed that the sample 10 actually adheres with a high strength comparable to the initial value even after the passage of time.

  As shown in Table 1, the adhesive sheet samples 3 to 9 each including a base material made of a PO / PLA resin material having a biomass degree of 35% or more had an adhesive force change rate within ± 15%. That is, it was confirmed that by using a PO / PLA resin material having a biomass degree of 35% or more, the rate of change in adhesive force can be significantly reduced (less than half of Samples 1 and 2).

<Example 3: Substrate dimensional change test>
Base material samples 1 to 11 were cut so that the length along the extrusion direction of the base material was 200 mm to prepare test pieces. For these test pieces, the length immediately after cutting (initial length B1) and the length after storage for 7 days in a dryer at 50 ° C. (length B2 after aging) were measured. The obtained measurement result was substituted into the following formula: (B2-B1) / B1 × 100; and the dimensional change rate D1 (%) of the base material sample was calculated.
Moreover, the pressure-sensitive adhesive sheet samples 1 to 11 were cut so that the length along the extrusion direction of the base material was 200 mm to produce a test piece, the length immediately after cutting (initial length C1), and 50 ° C. The length after storage for 7 days in the dryer (length C2 after aging) was measured. The obtained measurement result was substituted into the following formula: (C2-C1) / C1 × 100; and the dimensional change rate D2 (%) of the pressure-sensitive adhesive sheet sample was calculated.
The formation of the pressure-sensitive adhesive layer is determined by the difference (D2-D1) between the dimensional change rate D1 of the base material alone and the dimensional change rate D2 of the pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer on the base material. The effect on the environment was evaluated. The obtained results are shown in Table 2.

<Example 4: Evaluation of stiffness of base material>
The firmness of the substrate samples 1 to 11 was measured by the following method. That is, each base material sample was cut so that the width (TD) was 20 mm and the length (extrusion direction, that is, the length of MD) was 64 mm, and this was rounded to form a ring having a diameter of 20 mm and a width of 20 mm. The ring was crushed in the radial direction at a speed of 10 mm / min from a circular shape to a flat shape, and the maximum strength at this time was measured. The obtained results are shown in Table 2.

  As shown in Table 2, all of Samples 4 to 9 having a biomass degree of 40% or more had a difference in dimensional change due to formation of the pressure-sensitive adhesive layer within ± 0.3%. That is, it was confirmed that by using a PO / PLA resin material having a biomass degree of 40% or more, the difference in the dimensional change rate can be significantly reduced (to half or less of samples 1 to 3). This dimensional change rate difference is an excellent level comparable to that of PE laminated paper (Sample 11). Particularly good results were obtained with samples 5 to 9 having a biomass degree of 45% or more. In addition, the base material samples 4 to 9 having a biomass degree of 40% or more and 80% or less are all strong with PE laminated paper at the same thickness as PE laminated paper (thickness difference is within ± 10 μm). The difference in thickness was within ± 50%. In addition, although the base material samples 1 and 10 were transparent, all the base material samples 2-9 were cloudy, and showed the external appearance and feel similar to paper. The base material samples 4 to 8 having a biomass degree in the range of 40% or more and 70% or less had particularly good texture (texture close to PE laminated paper).

<Example 5: Production of adhesive sheet sample>
Substrate sample 12:
35 parts of LDPE, 60 parts of the same polylactic acid resin used for the base material sample 2, and 5 parts of the same compatibilizing agent used for the base material sample 2 were put into a twin-screw extruder and heated and melted. Extrusion was performed under conditions of a temperature of about 200 ° C. and a pressure of about 5 to 10 MPa to form a film having a thickness of 60 μm to 80 μm. Thereby, the base material sample 12 which a polymer component consists of LDPE and a polylactic acid resin and whose biomass degree is 58.8% was obtained.

Substrate sample 13:
The polylactic acid resin to be used was changed to a trade name “LACEA (Lacia) H-400” (biomass degree 100%) of Mitsui Chemicals, Inc. About the other point, it carried out similarly to the sample 12, and obtained the base material sample 13 whose polymer component consists of LDPE and polylactic acid and whose biomass degree is 60.0%.

Substrate sample 14:
The polylactic acid resin used was changed to the trade name “REVODE 101” (biomass degree 100%) of Zhejiang Haisheng Biomaterials Company. About the other point, it carried out similarly to the sample 12, and obtained the base material sample 14 whose polymer component consists of LDPE and polylactic acid and whose biomass degree is 60.0%.

Adhesive sheet samples 12-14:
A uniform adhesive layer having a thickness of about 20 μm was formed on one surface of each of the substrate samples 12 to 14 by applying a hot-melt adhesive in a heated and melted state. As a pressure-sensitive adhesive, SIS (trade name “Quintac 3450” of Nippon Zeon Co., Ltd.) is used as a base polymer, 100 parts of the base polymer, and 100 parts of tackifier resin (trade name “Escollet 1310” of Tonen Chemical Co., Ltd.). And SIS adhesive (hereinafter referred to as adhesive A-2) comprising 60 parts of process oil (trade name “Knife Rex 222B” from Japan Chemtech Co., Ltd.). Thus, the adhesive sheet samples 12-14 corresponding to each base material sample were produced.

<Example 6: Evaluation of rate of change in adhesive strength>
For the pressure-sensitive adhesive sheet samples 12 to 14, the initial adhesive strength, the post-aging adhesive strength, and the adhesive force change rate were determined in the same manner as in Example 2. The results are shown in Table 3 together with the schematic configuration of each adhesive sheet sample.

  As shown in Table 3, the pressure-sensitive adhesive sheet samples 12 to 14 provided with a base material made of a PO / PLA resin material having a biomass degree of 35% or more have an adhesive force change rate regardless of the type of polylactic acid. Within ± 15%. That is, it was confirmed that the rate of change in adhesive strength can be significantly reduced by using a PO / PLA resin material having a biomass degree of 35% or more.

<Example 7: Substrate dimensional change test>
The base material sample 12-14 was subjected to the same base material dimensional change test as in Example 3 to evaluate the influence of the formation of the pressure-sensitive adhesive layer on the dimensional change rate. Table 4 shows the obtained results.

<Example 8: Evaluation of stiffness of base material>
The stiffness of the substrate samples 12 to 14 was measured in the same manner as in Example 4. The results are shown in Table 4.

  As shown in Table 4, all samples 12 to 14 having a biomass degree of 40% or more have a difference in dimensional change rate of ± 0.5% due to the formation of the pressure-sensitive adhesive layer. It was confirmed that the difference could be highly suppressed. Moreover, as for the base material samples 12-14, all differed in the firm strength with PE laminated paper (sample 11) within +/- 50%. Moreover, all the base material samples 12-14 were cloudy, and showed the favorable external appearance and texture similar to paper.

1, 2, 5, 6 Adhesive sheet 10 Base material 21, 22 Adhesive layer 31, 32 Release liner 60 Adhesive sheet roll 62 Adhesive sheet 70 Base material 82 Adhesive layer

Claims (6)

A pressure-sensitive adhesive sheet comprising a sheet-like base material and a pressure-sensitive adhesive layer provided on at least one surface of the base material,
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is a rubber-based pressure-sensitive adhesive having a rubber-based polymer as a base polymer,
At least the surface portion of the base material where the pressure-sensitive adhesive layer is provided is mainly composed of polyolefin and polylactic acid, and is formed of a resin material having a biomass degree of 35% or more and less than 100% ,
The pressure-sensitive adhesive sheet, wherein the rubber-based polymer is at least one selected from the group consisting of styrene-butadiene rubber, polyisobutylene, styrene-isoprene-styrene block copolymer, and styrene-butadiene-styrene block copolymer .   The pressure sensitive adhesive sheet according to claim 1 whose biomass degree of said resin material is 40% or more and 80% or less.   The pressure-sensitive adhesive sheet according to claim 1, wherein the polyolefin is polyethylene.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the rubber-based pressure-sensitive adhesive is a pressure-sensitive adhesive having a styrene-isoprene-styrene block copolymer as a base polymer.   The adhesive sheet roll formed by winding the adhesive sheet as described in any one of Claim 1 to 4 in roll shape.   The pressure-sensitive adhesive sheet is wound in a roll shape so as to have a pressure-sensitive adhesive layer on at least the outer surface of the substrate, and the pressure-sensitive adhesive layer exposed on the outermost periphery is pressed against the surface to be processed while being pressed. The pressure-sensitive adhesive sheet roll according to claim 5, which is used by rolling.

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