JP6302676B2 - Multilayer adhesive sheet - Google Patents

Description

  The present invention relates to a multilayer pressure-sensitive adhesive sheet, and more particularly to a protective multilayer pressure-sensitive adhesive sheet excellent in sticking workability.

  For example, in the automobile and aircraft industries, a transparent adhesive sheet may be attached to prevent damage to the painted surface of a body such as an automobile. This pressure-sensitive adhesive sheet can be applied directly to the painted surface by hand using a squeegee, etc., but it may be misaligned during application, dirty with hands, or especially in areas where the 3D curved surface is severe. There were problems such as being unable to paste neatly. In addition, since the squeegee does not slide on the surface of the pressure-sensitive adhesive sheet, there are problems such as wrinkles and scratches on the pressure-sensitive adhesive sheet. Furthermore, in the protective adhesive sheet having a coating layer with a good surface slipperiness, the followability deteriorates in a severe part of the three-dimensional curved surface, and it is possible to follow and adhere to an adherend having a three-dimensional curved surface. A difficult problem occurred.

  In addition, from the viewpoint of weather resistance and the like, a pressure-sensitive adhesive sheet for protecting a coating film in which a coating layer made of a fluororesin is provided on a base material (for example, see JP-A-2009-299053) is also known. Insufficient and difficult to apply to complex sites.

JP-T-2001-520127 JP 2003-96140 A JP 59-41376 JP 2005-272558 A JP 2009-299053 A JP 2011-100542 A

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multilayer pressure-sensitive adhesive sheet that has surface slipperiness and curved surface followability and is excellent in pasting workability. .

  The multilayer pressure-sensitive adhesive sheet of the present invention is a multilayer pressure-sensitive adhesive sheet having at least a surface protective layer, a base material layer, and a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is provided on one surface of the base material layer, The surface protective layer is provided on the other surface of the base material layer, the static friction coefficient of the surface protective layer is 0.05 or more and 1.50 or less, and exceeds 0% of the multilayer adhesive sheet. The maximum stress value in a 10% stretched state is in the range of 0.5 MPa or more and 4.0 MPa or less.

  Here, the surface protective layer preferably contains a urethane-based polymer as a main component.

  The urethane polymer is preferably a water-based urethane polymer or a solvent-based urethane polymer.

  In the present invention, it is preferable that the maximum stress value of the surface protective layer from 0% to 100% is in the range of 5.0 MPa or more and 24.0 MPa or less.

  In the present invention, it is preferable that the maximum stress value in the stretched state exceeding 0% and up to 10% of the base material layer is in the range of 0.5 MPa or more and less than 3.5 MPa.

  Moreover, it is preferable that the said base material layer contains a urethane type polymer at least.

  Furthermore, the base material layer is preferably a urethane film or a composite film containing a (meth) acrylic polymer and a urethane polymer.

  In the present invention, the multilayer adhesive sheet is preferably used as a protective sheet for protecting the surface of the adherend.

  According to the present invention, the multilayer pressure-sensitive adhesive sheet has a curved surface followability and can be adhered neatly even in a portion where the three-dimensional curved surface is severe, and also has a good surface slipperiness, and has excellent pasting workability. Can be realized.

It is the schematic for demonstrating the method to measure a static friction coefficient. It is explanatory drawing for demonstrating the cross-sectional curve of the three-dimensional curved surface site | part regarding evaluation of sticking workability | operativity.

Hereinafter, the present invention will be described in detail.
The multilayer pressure-sensitive adhesive sheet of the present invention is a laminated sheet having at least a pressure-sensitive adhesive layer, a base material layer, and a surface protective layer. However, the surface protective layer is disposed on the outermost surface of the multilayer pressure-sensitive adhesive sheet, and the static friction coefficient of the surface protective layer needs to be 0.05 to 1.50, preferably 0.05 to 1.00. Yes, particularly preferably 0.05 to 0.5. If the static friction coefficient of the surface protective layer is less than 0.05 or greater than 1.50, good surface slipperiness cannot be realized.

  This surface protective layer preferably contains a urethane-based polymer as a main component. The urethane polymer is preferably a water-based urethane polymer or a solvent-based urethane polymer. The urethane polymer needs to be liquefied for processing or the like, but the urethane liquefied using an organic solvent such as toluene is called a solvent-based urethane polymer, and many of the urethane polymers are organic solvent-based. On the other hand, water-based urethane polymers are urethanes liquefied using water instead of organic solvents, and water-based urethane polymers are environmentally friendly materials because they can be liquefied without using organic solvents. It can be said.

  Examples of the water-based urethane polymer preferably used in the present invention include carbonate-based polymers, polycarbonate-based polymers, ester-based polymers, ether-based polymers, ester / acrylic polymers, and the like.

For example, as the water-based urethane polymer of the carbonate-based, trade name of Dai-ichi Kogyo Seiyaku Co., Ltd. "F-8082D" (100% modulus 24N / ^mm 2), the trade name of "Super Flex 420" (100 modulus 17N / mm ² ), Trade name “F-2954D” (100% modulus 5 N / mm ² ), trade name “F-2954D-5” (100% modulus 12 N / mm ² ), trade name “Superflex 470” (100% modulus 2) .5 N / mm ² ), trade name “Superflex 460” (100% modulus 0.9 N / mm ² ), “F-2968D” (100% modulus 1.5 N / mm ² ), etc. are commercially available As an ester-based water-based urethane polymer, products made by ADEKA Co., Ltd. "HUX 232" (100% modulus 25N / ^mm 2), the trade name of "HUX-380" (100 modulus 8.4N / ^mm 2), the trade name of "HUX-210" (100% modulus 2.1N / ^mm 2) Are commercially available, and examples of the polycarbonate-based water-based urethane polymer include ADEKA Corporation trade name “HUX-561” (100% modulus 5 N / mm ² ), trade name “HUX-564”. Are commercially available. Examples of ether-based water-based urethane polymers include ADEKA Corporation's trade name “HUX-350” (100% modulus 25 N / mm ² ), trade name “HUX- as 550 "(100% modulus ^{27N / mm 2 (10%)} ) and those commercially available Gerare, the aqueous urethane polymer of an ester / acrylic, K.K. ADEKA "HUX 401" (100% modulus 19N / mm ^2), and the like as those commercially available. In the present invention, among these commercially available products, those having a static friction coefficient of the surface protective layer within the scope of the present invention can be appropriately selected and used.

  The surface protective layer constituting the multilayer pressure-sensitive adhesive sheet of the present invention preferably satisfies a specific physical property value, for example, the maximum stress value in a stretched state exceeding 0% to 100% exceeds 5.0 MPa, The pressure is preferably 24.0 MPa or less, more preferably 10.0 MPa or more and 20.0 MPa or less, and particularly preferably 12.5 MPa or more and 17.5 MPa or less. If the maximum stress value of the surface protective layer is 5.0 to 24.0 MPa, it is easy to realize both the flexibility and the surface slipperiness with a good balance.

  Here, the maximum stress value means that the surface protective layer is subjected to a tensile test at a tensile speed of 200 mm / min, a distance between chucks of 30 mm, a room temperature of 20 ° C., and a thickness of 500 μm to obtain a stress-strain curve. The maximum value of stress per unit area (maximum stress value) up to 100% elongation state.

  The substrate layer constituting the multilayer pressure-sensitive adhesive sheet of the present invention is particularly limited as long as the maximum stress value in the stretched state exceeding 0% and up to 10% of the multilayer pressure-sensitive adhesive sheet satisfies 0.5 to 4.0 MPa. For example, it is preferable that at least a urethane polymer is included, and a film made of a urethane polymer or a composite film including a (meth) acrylic polymer and a urethane polymer is preferable. Here, the urethane polymer includes a homopolymer of urethane, a copolymer of urethane and another polymer other than urethane, and the like.

  The base material layer preferably has a maximum stress value of more than 0.5 MPa and less than 3.5 MPa, more preferably 1.0 MPa or more, exceeding 0% of the base material layer and up to 10%. 3.0 MPa or less, particularly preferably 1.5 MPa or more and 2.0 MPa or less. If the maximum stress value in the stretched state exceeding 0% of the base material layer and 10% is 0.5 to 3.5 MPa, good curved surface followability can be achieved. Moreover, when this maximum stress value is too low (for example, less than 0.5 MPa), the handling property (ease of handling of the tape) when affixing to a large-area adherend is lowered.

  Here, the maximum stress value means that a base material layer (width 10 mm, length 160 mm) is subjected to a tensile test at a tensile speed of 200 mm / min, a distance between chucks of 100 mm, and 23 ° C. to obtain a stress-strain curve. The maximum value (maximum stress value) of stress per unit area from 0% to 10% of the elongation.

  In the present invention, as the urethane polymer used for the base material layer, a urethane homopolymer or copolymer satisfying the stress value is preferably used. For example, the urethane homopolymer is obtained by reacting a polyol and a polyisocyanate. Can be obtained. Examples of the urethane-based polymer preferably used in the present invention include adipate / ester-based thermoplastic polyurethane, polyether-based thermoplastic polyurethane, polycarbonate-based thermoplastic polyurethane, and polycaprolactone-based thermoplastic polyurethane. For example, a product made by Nippon Matai Co., Ltd. can be commercially obtained as an adipate ester-based thermoplastic polyurethane.

  Moreover, it is preferable that the base material layer which comprises the multilayer adhesive sheet of this invention is a composite film containing a (meth) acrylic-type polymer and a urethane polymer.

  The weight ratio of (meth) acrylic polymer to urethane polymer in the composite film is preferably in the range of (meth) acrylic polymer / urethane polymer = 1/99 to 80/20. When the content ratio of the (meth) acrylic polymer is less than 1/99, the viscosity of the precursor mixture is increased and workability may be deteriorated. When it exceeds 80/20, flexibility and strength as a film are obtained. It may not be possible.

  In the present invention, the (meth) acrylic polymer is preferably formed using an acrylic component containing at least a (meth) acrylic acid monomer and a monofunctional (meth) acrylic monomer, and in particular, a glass transition of a homopolymer. It is preferable to use a monofunctional (meth) acrylic monomer having a temperature (Tg) of 0 ° C. or higher. Furthermore, in this invention, it is preferable that a (meth) acrylic-type polymer uses the acrylic component which further contains the monofunctional (meth) acrylic-type monomer whose glass transition temperature (Tg) of a homopolymer is less than 0 degreeC.

  In the present invention, the (meth) acrylic acid monomer is a (meth) acrylic monomer having a carboxyl group, and examples thereof include acrylic acid, methacrylic acid, maleic acid, and crotonic acid. Among these, acrylic acid is particularly preferable. The content of the (meth) acrylic acid-based monomer is 1% by weight or more and 15% by weight or less, and preferably 2% by weight or more and 10% by weight or less in the composite film precursor described later. If the content of the (meth) acrylic acid monomer is less than 1% by weight, it takes a long time for the reaction, making it very difficult to form a film, and there may be a problem that the strength of the film is not sufficient. . When the content of the (meth) acrylic acid monomer exceeds 15% by weight, the water absorption rate of the film increases, which may cause a problem in water resistance. When a composite film is used as the substrate, the (meth) acrylic acid monomer greatly affects the compatibility with the urethane component and the acrylic component, and is an essential component having a very important function.

  In the present invention, the term “film” includes a sheet, and the term “sheet” includes a film. Further, in the present invention, when “(meth) acryl” is displayed as in the case of a (meth) acrylic polymer and a (meth) acrylic acid monomer, the term “methacrylic” and “acrylic” are collectively used. Further, even when “acrylic” is displayed, the concept includes methacrylic if there is no problem in general sense.

  In the present invention, examples of the monofunctional (meth) acrylic monomer having a Tg of 0 ° C. or higher include acryloylmorpholine, isobornyl acrylate, dicyclopentanyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and lauryl acrylate. It is done. These may be used alone or in combination of two or more.

  In the present invention, it is preferable to use at least one selected from the group consisting of acryloylmorpholine, isobornyl acrylate, and dicyclopentanyl acrylate as a monofunctional (meth) acrylic monomer having a Tg of 0 ° C. or higher. It is more preferable to use acryloyl morpholine and / or isobornyl acrylate, or acryloyl morpholine and / or dicyclopentanyl acrylate, and it is particularly preferable to use isobornyl acrylate.

  The content of the monofunctional (meth) acrylic monomer having a Tg of 0 ° C. or higher is preferably 20 wt% or more and 99 wt% or less in the acrylic component, and is 30 wt% or more and 98 wt% or less. Is more preferable. If the content of the monofunctional (meth) acrylic monomer is less than 20% by weight, there may be a problem that the strength of the film is not sufficient, and if it exceeds 99% by weight, the rigidity of the film becomes too high and becomes brittle. There is a case.

In the present invention, examples of monofunctional (meth) acrylic monomers having a Tg of less than 0 ° C. include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isobutyl acrylate, 2-methoxyethyl acrylate, tetrahydro Examples include fluorofuryl acrylate, phenoxyethyl acrylate, ethoxyethyl acrylate, and 3-methoxybutyl acrylate. These may be used alone or in combination of two or more.
In the present invention, it is particularly preferable to use n-butyl acrylate as a monofunctional (meth) acrylic monomer having a Tg of less than 0 ° C.

  A monofunctional (meth) acrylic monomer having a Tg of less than 0 ° C. may not be contained (content is 0% by weight), but if contained, the content is from 0% by weight in the acrylic component. The amount is preferably 50% by weight or less, more preferably more than 0% by weight and 45% by weight or less. When the content of the monofunctional (meth) acrylic monomer exceeds 50% by weight, there may be a problem that the strength of the film is not sufficient.

  The type, combination, amount of use, and the like of the (meth) acrylic monomer are appropriately determined in consideration of compatibility with urethane, polymerizability at the time of photocuring such as radiation, and characteristics of the high molecular weight obtained.

  In the present invention, together with the (meth) acrylic monomer, vinyl acetate, vinyl propionate, styrene, acrylamide, methacrylamide, mono- or diester of maleic acid, and derivatives thereof, N-methylolacrylamide, glycidyl acrylate, glycidyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, 2-hydroxypropyl acrylate, N, N-dimethylacrylamide, N, N-diethylacrylamide, imide acrylate, N-vinylpyrrolidone, oligoester acrylate , Ε-caprolactone acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, methoxylated cyclododecatriene Acrylate may be copolymerized monomer such as methoxyethyl acrylate. Note that the types and amounts of the monomers to be copolymerized are appropriately determined in consideration of the characteristics of the composite film.

  In addition, other polyfunctional monomers can be added within a range that does not impair the characteristics. Polyfunctional monomers include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol. Examples include tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane acrylate, epoxy acrylate, polyester acrylate, and the like, and trimethylolpropane tri (meth) acrylate is particularly preferable.

  The polyfunctional monomer may be contained in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the acrylic monomer. If the content of the polyfunctional monomer is 1 part by weight or more, the cohesive force of the composite film is sufficient, and if it is 20 parts by weight or less, the elastic modulus does not become too high, and the unevenness of the adherend surface is reduced. Can follow.

  The urethane polymer is obtained by reacting a diol with a diisocyanate. In general, a catalyst is used for the reaction between the hydroxyl group of the diol and the isocyanate. However, according to the present invention, the reaction is promoted without using an environmental load catalyst such as dibutyltin dilaurate or tin octoate. Can be made.

  Examples of the low molecular weight diol include divalent alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and hexamethylene glycol.

  Further, as the high molecular weight diol, polyether polyol obtained by addition polymerization of ethylene oxide, propylene oxide, tetrahydrofuran or the like, or the above-mentioned divalent alcohol, 1,4-butanediol, 1,6-hexanediol, etc. And polyester polyols composed of polycondensates of dihydric basic acids such as adipic acid, azelaic acid and sebacic acid, acrylic polyols, carbonate polyols, epoxy polyols and caprolactone polyols. Among these, for example, polyoxytetramethylene glycol (PTMG), polyalkylene carbonate diol (PCD) and the like are preferably used.

  Examples of the acrylic polyol include a copolymer of a monomer having a hydroxyl group, a copolymer of a hydroxyl group-containing substance and an acrylic monomer, and the like. Examples of the epoxy polyol include an amine-modified epoxy resin.

  In the present invention, the urethane polymer does not contain a crosslinked structure. The diol used for forming the urethane polymer is preferably a linear (linear) diol. However, the diol may be a side chain diol or a diol containing a branched structure as long as the condition that the urethane polymer does not form a crosslinked structure is satisfied. That is, the urethane polymer constituting the composite film of the present invention does not contain a crosslinked structure, and therefore is completely different from the IPN structure.

  In the present invention, the above diols can be used alone or in combination in consideration of solubility in acrylic monomers, reactivity with isocyanates, and the like. When the strength is required, it is effective to increase the amount of the urethane hard segment by the low molecular weight diol. When importance is attached to elongation, a diol having a large molecular weight is preferably used alone. Polyether polyols are generally inexpensive and have good water resistance, and polyester polyols have high strength. In the present invention, the type and amount of the polyol can be freely selected according to the use and purpose, and the viewpoints such as the properties of the base material to be applied, reactivity with isocyanate, compatibility with acrylic, etc. From the above, the type, molecular weight and amount of use of the polyol can be selected as appropriate.

  Examples of the diisocyanate include aromatic, aliphatic and alicyclic diisocyanates, dimers and trimers of these diisocyanates. Examples of aromatic, aliphatic and alicyclic diisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), phenylene diisocyanate (PPDI), m. -Tetramethylxylylene diisocyanate (TMXDI), methylcyclohexane diisocyanate (hydrogenated TDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexane diisocyanate (hydrogenated PPDI), bis (isocyanatomethyl) cyclohexane (hydrogenated XDI), norbornene Diisocyanate (NBDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), butanedi Cyanate, 2,4-hexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and the like. Moreover, these dimers, trimers, and polyphenylmethane diisocyanate are used. Examples of the trimer include isocyanurate type, burette type, and allophanate type, and can be used as appropriate.

  Among these, in particular, methylcyclohexane diisocyanate (hydrogenated TDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexane diisocyanate (hydrogenated PPDI), bis (isocyanatomethyl) cyclohexane (hydrogenated XDI), norbornene diisocyanate (NBDI). ), Aliphatic and alicyclic diisocyanates such as isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), butane diisocyanate, 2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate are preferred. used. This is because it is not preferable to use an aromatic diisocyanate containing a benzene ring because a colored substance having a conjugated structure is easily generated by a photoreaction. In the present invention, it does not contain a benzene ring, is hardly yellowed, and has no yellow color. Modified aliphatic and alicyclic diisocyanates are preferably used.

  These diisocyanates can be used alone or in combination. From the viewpoints of the characteristics of the support to which the composite film is applied (applied or the like), solubility in acrylic monomers, reactivity with hydroxyl groups, and the like, the type and combination of diisocyanates may be appropriately selected.

  In the present invention, the urethane polymer is hexamethylene diisocyanate (HDI), hydrogenated tolylene diisocyanate (HTDI), hydrogenated 4,4-diphenylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), and hydrogenated xylene diisocyanate. It is preferably formed using at least one diisocyanate selected from the group consisting of (HXDI), and hydrogenated xylene diisocyanate is particularly preferable.

  In the present invention, the amount of the diol component and diisocyanate component used to form the urethane polymer is preferably NCO / OH (equivalent ratio) of 1.1 or more and 2.0 or less, preferably 1.12 or more, 1 Is more preferably 1.60 or less, and particularly preferably 1.15 or more and 1.40 or less. When the NCO / OH (equivalent ratio) is less than 1.1, the molecular weight of the urethane polymer becomes too large, the viscosity of the composite film precursor (syrup solution) becomes large, and the work becomes difficult in the subsequent sheeting process. There is. Moreover, when NCO / OH (equivalent ratio) exceeds 2.0, the molecular weight of a urethane polymer will become small and break strength will fall easily.

  In the present invention, the ratio of the acrylic component and the urethane component forming the composite film is a weight ratio of acrylic component / urethane component of 0.25 or more and 4.00 or less, preferably 0.4 or more, 2 .4 or less, particularly preferably 0.5 or more and 1.9 or less. When the acrylic component / urethane component is less than 0.25, the viscosity of the syrup solution becomes large, and the work may be difficult in the subsequent sheet forming step. On the other hand, when the acrylic component / urethane component exceeds 4.00, the amount of urethane polymer in the composite film becomes less than 25%, the tensile strength at break is lowered, and it may not be practically used.

  A hydroxyl group-containing acrylic monomer may be added to the urethane polymer. By adding a hydroxyl group-containing acrylic monomer, a (meth) acryloyl group can be introduced at the molecular end of the urethane prepolymer, and a copolymerizability with a (meth) acrylic monomer is imparted. It is possible to improve the S-S characteristics such as the breaking strength. Examples of the hydroxyl group-containing acrylic monomer used here include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and the like. It is preferable that the usage-amount of a hydroxyl-containing acrylic monomer is 0.1-10 weight part with respect to 100 weight part of urethane polymers, More preferably, it is 1-5 weight part.

  In the present invention, a small amount of solvent may be added to adjust the viscosity of the coating. The solvent can be appropriately selected from commonly used solvents, and examples thereof include ethyl acetate, toluene, chloroform, dimethylformamide and the like.

  In the present invention, the composite film includes, for example, an acrylic monomer as a diluent, a reaction between diol and diisocyanate in the acrylic monomer to form a urethane polymer, and the acrylic monomer and the urethane polymer as main components. Apply the mixture onto a support (exfoliated if necessary), etc., and ionize α rays, β rays, γ rays, neutron rays, electron rays, etc., depending on the type of photopolymerization initiator A composite film can be formed by irradiating and curing radiation such as actinic radiation and ultraviolet rays, visible light, and the like, and then peeling and removing the support and the like. Or it can also obtain in the form by which the composite film was laminated | stacked on the support body etc., without peeling and removing a support body etc.

  Specifically, after dissolving the diol in the acrylic monomer, diisocyanate or the like is added and reacted with the diol to adjust the viscosity, and this is peeled off to the support or the like, or if necessary, the support or the like is peeled off After coating on the treated surface, the composite film can be obtained by curing using a low-pressure mercury lamp or the like. In this method, the acrylic monomer may be added all at once during the urethane synthesis, or may be added in several divided portions. Further, after the diisocyanate is dissolved in the acrylic monomer, the diol may be reacted. According to this method, the molecular weight is not limited and a high molecular weight polyurethane can be produced, so that the molecular weight of the finally obtained urethane can be designed to an arbitrary size.

  At this time, in order to avoid polymerization inhibition due to oxygen, a release sheet (separator, etc.) may be placed on the mixture coated on the substrate sheet, etc. to block oxygen, or filled with an inert gas. The oxygen concentration may be lowered by placing a substrate in the container.

  In the present invention, the type of radiation and the type of lamp used for irradiation can be selected as appropriate, such as a low-pressure lamp such as a fluorescent chemical lamp, a black light and a sterilization lamp, a high-pressure such as a metal halide lamp and a high-pressure mercury lamp. A lamp or the like can be used.

Irradiation amounts such as ultraviolet rays can be arbitrarily set according to required film characteristics. Generally, the dose of ultraviolet rays, 100~5,000mJ / cm ^2, preferably not 1,000~4,000mJ / cm ^2, more preferably a 2,000~3,000mJ / cm ^2. When the irradiation amount of ultraviolet rays is less than 100 mJ / cm ² , a sufficient polymerization rate may not be obtained, and when it is more than 5,000 mJ / cm ² , deterioration may be caused.

  In addition, the temperature at the time of irradiation with ultraviolet rays or the like is not particularly limited and can be arbitrarily set. However, if the temperature is too high, a termination reaction due to polymerization heat is likely to occur, which may cause deterioration of characteristics. The temperature is usually 70 ° C. or lower, preferably 50 ° C. or lower, more preferably 30 ° C. or lower.

  The mixture containing a urethane polymer and an acrylic monomer as main components contains a photopolymerization initiator. The photopolymerization initiator can be used without any particular limitation. For example, ketal photopolymerization initiator, α-hydroxyketone photopolymerization initiator, α-aminoketone photopolymerization initiator, acylphosphine oxide photopolymerization initiator. Polymerization initiator, bezophenone photopolymerization initiator, thioxanthone photopolymerization initiator, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator Agents, benzoin photopolymerization initiators, benzyl photopolymerization initiators, and the like can be used.

  Examples of the ketal photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one (for example, “Irgacure 651” manufactured by Ciba Specialty Chemicals Co., Ltd.). Etc.).

  Examples of the α-hydroxyketone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (such as “Irgacure 184” manufactured by Ciba Japan Co., Ltd.), 2-hydroxy-2- Methyl-1-phenylpropan-1-one (commercially available products such as “Darocur 1173” manufactured by Ciba Japan Ltd.), 1- [4- (2-hydroxyethoxy) -phenyl] -2 -Hydroxy-2-methyl-1-propan-1-one (such as “Irgacure 2959” manufactured by Ciba Japan Co., Ltd.) can be used.

  As the α-aminoketone photopolymerization initiator, for example, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (commercially available is Ciba "Irgacure 907" manufactured by Japan Co., Ltd.), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (commercially available products manufactured by Ciba Japan Co., Ltd.) "Irgacure 369" etc.).

  Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (commercially available products such as “Lucirin TPO” manufactured by BASF).

  Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole. And methyl ether.

  Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl). Examples include dichloroacetophenone.

  Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride, and examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (O-ethoxycarbonyl) -oxime and the like.

  Examples of the benzoin photopolymerization initiator include benzoin, and examples of the benzyl photopolymerization initiator include benzyl.

  Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like.

  Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

  For each layer of the pressure-sensitive adhesive sheet of the present invention, that is, for the base material layer, the surface protective layer, the pressure-sensitive adhesive layer, etc., additives that are usually used as necessary, for example, ultraviolet absorbers, antioxidants, anti-aging Agents, fillers, pigments, colorants, flame retardants, antistatic agents, light stabilizers, and the like can be added within a range that does not impair the effects of the present invention. These additives are used in normal amounts depending on the type.

When adding an ultraviolet absorber, the ultraviolet absorber is preferably added to the substrate layer or the surface protective layer. Examples of the ultraviolet absorber (UVA) include 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (for example, “TINUVIN PS manufactured by Ciba Japan Co., Ltd.) as a benzotriazole ultraviolet absorber. )), Benzenepropanoic acid and 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C ₇ -C ₉ side chain and straight chain alkyl) Ester compound (for example, “TINUVIN 384-2” manufactured by Ciba Japan), octyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) Phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H A mixture with benzotriazol-2-yl) phenyl] propionate (for example, “TINUVIN 109” manufactured by Ciba Japan), 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl) -1-phenylethyl) phenol (for example, “TINUVIN 900” manufactured by Ciba Japan), 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol (for example, “TINUVIN 928” manufactured by Ciba Japan), methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert -Butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product (for example, manufactured by Ciba Japan) TINUVIN 1130 "), 2- (2H-benzotriazol-2-yl) -p-cresol (for example," TINUVIN P "manufactured by Ciba Japan), 2- [5-chloro (2H) -benzotriazole-2 -Yl] -4-methyl-6- (tert-butyl) phenol (eg, TINUVIN 326 manufactured by Ciba Japan), 2- (2H-benzotriazol-2-yl) -4,6-di-tert -Pentylphenol (eg, TINUVIN 328 manufactured by Ciba Japan), 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (eg, Ciba -TINUVIN 329 manufactured by Japan)) 2-2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- 1,1,3,3-tetramethylbutyl) phenol] (for example, TINUVIN 360 manufactured by Ciba Japan), methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert- Reaction product of butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 (for example, “TINUVIN 213” manufactured by Ciba Japan), 2- (2H-benzotriazol-2-yl) -6-dodecyl-4 -Methylphenol (for example, "TINUVIN 571" manufactured by Ciba Japan), 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalimide-methyl) -5-methylphenyl] benzotriazole ( For example, “Sumisorb 250” manufactured by Sumitomo Chemical Co., Ltd.), 2,2′-methylenebis [6- (benzotria Lumpur-2-yl) -4-tert-octylphenol] (e.g., ADEKA made of "ADKSTAB LA31"), and the like.

  Moreover, as a hydroxyphenyl triazine type ultraviolet absorber, for example, 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and [ Reaction product with (C10-C16, mainly C12-C13 alkyloxy) methyl] oxirane (for example, “TINUVIN 400” manufactured by Ciba Japan), 2- (2,4-dihydroxyphenyl) -4,6 Reaction product of bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester (for example, “TINUVIN 405” manufactured by Ciba Japan), 2 , 4-Bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3,5-triazine (e.g. “TINUVIN 460” manufactured by Ciba Japan)), 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol (for example, Ciba Japan “TINUVIN 1577”), 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine (for example, And “TINUVIN 479” manufactured by Ciba Japan Co., Ltd.).

  Examples of the benzophenone ultraviolet absorber include “CHIMASSORB 81” manufactured by Ciba Japan. Examples of the benzoate ultraviolet absorber include 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (for example, “TINUVIN 120” manufactured by Ciba Japan Co., Ltd.). ) And the like.

  In this invention, the said ultraviolet absorber can be used individually or in combination of 2 or more types.

  When the ultraviolet absorber is added to the base material layer, the total amount of the ultraviolet absorber is preferably 0.1% by weight or more and 4.0% by weight or less with respect to 100% by weight of the base material layer. More preferably, the content is 0.5% by weight or more and 2.0% by weight or less. If the content of the UV absorber is 0.1% by weight or more, absorption of UV light causing deterioration or coloring is sufficient, and if it is 4.0% by weight or less, coloring by the UV absorber itself is caused. There is no.

  The light stabilizer used in the present invention is preferably a hindered amine light stabilizer (HALS). As the hindered amine light stabilizer used in the present invention, for example, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (for example, manufactured by Ciba Japan Co., Ltd.) “TINUVIN 622”), a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and N, N ′, N ″, N ′ ″-tetrakis- (4,6-Bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10 -One-to-one reaction product with diamine (for example, "TINUVIN 119" manufactured by Ciba Japan), dibutylamine, 1,3-triazine, N, N'-bis (2,2,6, A polycondensate of 6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine (for example, manufactured by Ciba Japan) “TINUVIN 2020”), poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {2,2,6,6-tetra Methyl-4-piperidyl} imino] hexamethylene {(2,6,6-tetramethyl-4-piperidyl) imino}) (for example, “TINUVIN 944” manufactured by Ciba Japan), bis (1,2,2 , 6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (for example, “TINUVIN manufactured by Ciba Japan Ltd.) 65 "), bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (for example," TINUVIN 770 "manufactured by Ciba Japan), bis (2,2,6,6-decane) Reaction product of tetramethyl-1- (octyloxy) -4-piperidinyl) ester (1,1-dimethylethyl hydroperoxide) and octane (for example, “TINUVIN 123” manufactured by Ciba Japan), bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate (for example, manufactured by Ciba Japan Ltd. "TINUVIN 144"), cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1, , 5-triazine and 2-aminoethanol (for example, “TINUVIN 152” manufactured by Ciba Japan), bis (1,2,2,6,6-pentamethyl-4- Piperidyl) sebacate and a mixture of methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate (for example, “TINUVIN 292” manufactured by Ciba Japan).

  It is preferable that the thickness of the surface protective layer which comprises the multilayer adhesive sheet of this invention is 2-50 micrometers, More preferably, it is 5-40 micrometers, More preferably, it is 8-30 micrometers. If the thickness of the surface protective layer is less than 2 μm, a defect site where the surface protective layer is not formed, such as pinholes, is likely to occur, and the characteristics of the surface protective layer may not be fully exhibited. Moreover, when it exceeds 50 micrometers, the physical property of a surface protective layer may reduce the physical property of a base material layer.

  The thickness of the base material layer constituting the multilayer pressure-sensitive adhesive sheet of the present invention can be appropriately selected according to the purpose and the like, for example, according to the type and location of the object to be covered and protected, and is not particularly limited, but is 100 μm or more. It is preferable that it is 150 micrometers or more, and it is especially preferable that it is 200 micrometers or more. Moreover, it is preferable that the upper limit of thickness is about 1 mm. The thickness of the base material layer is preferably about 50 to 800 μm, and more preferably about 100 to 600 μm, for example, in the case of chipping used for protecting the body of an automobile. Moreover, in the case of an aircraft use, it is about 50-1,000 micrometers, More preferably, it is about 200-800 micrometers. In the case of a motorcycle application, it is preferably about 50 to 800 μm, more preferably about 100 to 600 μm.

  In the present invention, for example, the surface protective layer can be formed using a coating solution for a surface protective layer comprising a water-based urethane polymer or a solvent-based urethane polymer. For example, a laminate (multilayer sheet) can be obtained by applying a surface protective layer coating solution on a base material layer, drying and curing to form a surface protective layer.

  Alternatively, for example, the surface protective layer coating solution is applied onto the peeled PET film and dried to form the surface protective layer. On this surface protective layer, a laminate (multi-layer sheet) can be obtained by applying a coating solution for a composite film containing an acrylic monomer and a urethane polymer and irradiating it with ultraviolet rays or the like to cure.

  In the present invention, the multilayer sheet can be laminated with another film on the base material layer as long as the effects of the present invention are not impaired. Examples of materials for forming other films include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyimide (PI), and polyetheretherketone (PEEK). Besides thermoplastic resins such as polyvinyl chloride (PVC), polyvinylidene chloride resins, polyamide resins, polyurethane resins, polystyrene resins, acrylic resins, fluorine resins, cellulose resins, polycarbonate resins, etc. And thermosetting resins.

  The multilayer pressure-sensitive adhesive sheet of the present invention preferably has a structure having a surface protective layer as the outermost surface layer on one surface of the base material layer and a pressure-sensitive adhesive layer on the other surface.

  The pressure-sensitive adhesive that forms this pressure-sensitive adhesive layer is not particularly limited, and general materials such as acrylic, rubber-based, silicon-based, etc. can be used, but adhesion at low temperatures and retention at high temperatures, In view of cost and the like, an acrylic adhesive is preferable.

  As an acrylic adhesive, an acrylic copolymer obtained by copolymerizing a monomer component mainly composed of an acrylate ester and a monomer component having a functional group such as a carboxyl group or a hydroxyl group (may be two or more types) An acrylic pressure-sensitive adhesive containing can be used.

  Examples of acrylic esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec- Butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) Acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, Sil (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl ( And (meth) acrylate, eicosyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, and the like. These alkyl (meth) acrylates can be used alone or in combination of two or more.

  The following monomer components can be copolymerized with the alkyl (meth) acrylate. Examples of copolymerizable monomer components include monomers containing carboxyl groups such as (meth) acrylic acid, itaconic acid, maleic acid, crotonic acid, fumaric acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, and the like. ; 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxy (meth) acrylate Hydroxyl group-containing monomers such as octyl, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) -methyl acrylate; glycidyl (meth) acrylate, methyl glycidyl (meth) Acry Glycidyl group-containing monomers such as acrylate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethyl ( (Meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, N-vinyl-2-piperidone, N-vinyl-3 -Morpholinone, N-vinyl-2-caprolactam, N-vinyl-2-pyrrolidone, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-cyclohexylmaleimide, N -Phenylmaleimide, N-a Leroy pyrrolidine, t- butyl aminoethyl (meth) nitrogen-containing monomers such as acrylates, styrene derivatives and styrene, monomers such as vinyl acetate and the like. One or more of these monomers can be used by copolymerizing with (meth) acrylic acid ester as required.

  The pressure-sensitive adhesive used in the present invention comprises at least one selected from the group consisting of 2-ethylhexyl acrylate and isononyl acrylate, and at least one carboxyl group-containing monomer selected from the group consisting of acrylic acid and methacrylic acid. It is preferable to include. That is, the pressure-sensitive adhesive used in the present invention can use a copolymer obtained by copolymerizing 2-ethylhexyl acrylate, isononyl acrylate, or the like as a main monomer and a carboxyl group-containing monomer such as acrylic acid or methacrylic acid. .

  The thickness of the pressure-sensitive adhesive layer is not particularly limited and can be arbitrarily set, but is usually preferably 20 μm or more, more preferably 30 μm or more, and particularly preferably 40 μm or more. However, the upper limit is usually preferably about 100 μm.

  In the present invention, the pressure-sensitive adhesive layer is formed by, for example, applying a solvent-based or emulsion-based pressure-sensitive adhesive directly to the base material layer and drying, or applying these pressure-sensitive adhesives to release paper to form a pressure-sensitive adhesive layer in advance. In addition, a method of bonding the pressure-sensitive adhesive layer to the base material layer or the like can be applied. It is also possible to apply a method in which a radiation curable pressure-sensitive adhesive is applied to a base material layer, and both the pressure-sensitive adhesive layer and the film are irradiated with radiation to simultaneously cure and form the base material layer and the pressure-sensitive adhesive layer. it can.

In this invention, the static friction coefficient of a multilayer adhesive sheet is calculated | required by measuring the static friction coefficient of an outermost surface layer according to JISK7125. That is, a multilayer adhesive sheet of a predetermined size is fixed on a standard test plate, a sliding piece is placed on the multilayer adhesive sheet, the sliding piece is pulled while applying normal force (uniform pressure distribution), and the maximum load is measured. Then, the static friction coefficient is obtained using the following calculation formula.
μ = Fs / Fp
(Μ: static friction coefficient, Fs: static friction force (N), Fp: normal force)

  In the multilayer pressure-sensitive adhesive sheet of the present invention, the maximum stress value in the stretched state exceeding 0% to 10% of the multilayer pressure-sensitive adhesive sheet needs to be 0.5 to 4.0 MPa, preferably 1.0 MPa or more, 3 0.0 MPa or less, particularly preferably 1.5 MPa or more and 2.0 MPa or less. If the maximum stress value in the stretched state of 10% exceeding 0% of the multilayer pressure-sensitive adhesive sheet is 0.5 to 4.0 MPa, good curved surface followability can be achieved. Moreover, when this maximum stress value is too low (for example, less than 0.5 MPa), the handling property (ease of handling of the tape) when affixing to a large-area adherend is lowered.

  Here, the maximum stress value means that a multilayer pressure-sensitive adhesive sheet (width 10 mm, length 160 mm) is subjected to a tensile test at a tensile speed of 200 mm / min, a distance between chucks of 100 mm, and 23 ° C. to obtain a stress-strain curve. The maximum value of stress per unit area (maximum stress value) up to 1% to 10% elongation state.

  The multilayer pressure-sensitive adhesive sheet of the present invention is required to be transparent in order to reflect the color and the like of the coated surface of the adherend in the appearance as it is, but with the same color as the color of the painted surface using a pigment or the like. It may be colored or colored in another color and used as a paint substitute adhesive sheet.

  In the multilayer adhesive sheet of the present invention, an application sheet can be used for, for example, positioning for attaching, in order to improve the attaching operation of the adhesive sheet.

The multilayer pressure-sensitive adhesive sheet of the present invention has excellent followability to a curved surface, and exhibits excellent pasting workability even on an adherend having a severe three-dimensional curved surface. Therefore, it is suitable as a pressure-sensitive adhesive sheet for protecting an adherend having a large area (attachment) and an adherend having a severe three-dimensional curved surface. In addition, for protection to protect painted surfaces of transport machines, for example, motorcycles, bicycles, rail cars, ships, snowmobiles, gondola, lifts, escalators, automobiles, airplanes, etc., especially automobiles, airplanes, motorcycles, etc. Suitable for applications such as multilayer adhesive sheets, light guide films for mobile phones, sealing materials for electrode substrates, decorative films for handrails of escalators, and transparent films used in combination with transparent glass.

  Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, parts mean parts by weight and% means% by weight. The measurement methods and evaluation methods used in the following examples are shown below.

(Measurement method and evaluation method)
(1) Measurement of maximum stress value A multilayer pressure-sensitive adhesive sheet was cut into a width of 10 mm and a length of 160 mm, and a tensile test was performed at a tensile speed of 200 mm / min, a distance between chucks of 100 mm, and 23 ° C. to obtain a stress-strain curve. . The maximum value (maximum stress value) of the stress per unit area when the multilayer adhesive sheet was stretched by 0% to 10% was determined.

(2) Measurement of coefficient of static friction The multilayer adhesive sheet was cut into a size of 80 mm width × 100 mm length, and this multilayer adhesive sheet was stuck on a standard test plate (JISG 3141: manufactured by Nippon Test Panel Co., Ltd.) A sliding piece was placed on the adhesive sheet, and the static friction coefficient of the outermost surface layer (ex. Surface protective layer) was measured according to JISK7125. The contact area of the sliding piece is 63 mm × 63 mm, the total mass of the sliding piece is 200 g (1.96 N), and a squeegee cloth is attached to the contact surface of the sliding piece with the adhesive sheet surface, and the sliding speed is 100 mm / min. Measurement was performed by pulling the sliding piece under the conditions. The static friction coefficient was calculated | required using the following calculation formula according to JISK7125.

μ = Fs / Fp
(Μ: static friction coefficient, Fs: static friction force (N), Fp: normal force generated by the mass of the sliding piece (= 9.8 N / kg × 0.2 kg))

  FIGS. 1A and 1B are schematic views for explaining a method for measuring a static friction coefficient. As shown in FIG. 1 (a), the sample 1 is fixed to the counterpart material 2 so that the measurement surface of the sample 1 (ex. Multilayer adhesive sheet) faces upward, that is, for example, the adhesive layer of the multilayer adhesive sheet. Is affixed onto the mating material 2 (ex. Standard test plate) and fixed, a sliding piece (contact area 63 mm × 63 mm) is placed on the measurement surface of the sample 1, and the sliding piece is tested at a test speed of 100 mm / min. Pull on. Since the normal force is generated by the sliding piece, the bottom surface of the sliding piece is covered with an elastic material (felt or the like) in order to apply a uniform pressure distribution. The sample 1 may be directly fixed to the counterpart material 2, but may be fixed by being attached to an auxiliary plate such as a support. The sliding piece may be connected to the load cell via a spring. As shown in FIG. 1 (b), the force increases linearly to give friction and reach a maximum load. This peak represents the static friction force (Fs). The static friction coefficient is obtained from the above calculation formula (μ = Fs / Fp).

(3) Evaluation of sticking workability Three-dimensional curved surface part (size: length 300 mm × width 210 mm, curvature: cross section curve consisting of maximum convex curvature (R = 43.3), maximum concave curvature (R = 34.6) A pasting operation of pasting a multilayer pressure-sensitive adhesive sheet was performed on a part having a curved surface including (see FIG. 2) to evaluate the pasting workability. That is, each of “surface slipperiness” and “curved surface followability” was evaluated by a score (1 to 4 points), and a total score of both was obtained. However, there are three pasting workers who participated in the test. In addition, the standard for scoring “surface slipperiness” and “curved surface followability” is 4 points for a very good level, 3 points for a problem-free level, 2 points for a level that needs a little improvement, and a level that requires improvement. Is one point, and is shown as an average value of three workers.

From the total score of the pasting workability, the pasting workability was evaluated based on the following evaluation criteria. Here, the total score of the pasting workability means the score of curved surface followability + the score of surface slipperiness.

Evaluation criteria:
“Excellent” The total score for pasting workability is 5 points or more “Good” The total score for pasting workability is greater than 4.5 points and less than 5 points “Inferior” The total score for pasting workability is 4.5 points or less

  When “good” is indicated in the above evaluation criteria, if the curved surface followability is poor, the work of pressing strongly with the squeegee and the work of rubbing with the squeegee many times increase, and the work efficiency slightly decreases. Moreover, when curved surface followability is bad, the work of pulling and repeating work, that is, the work of peeling off the pasted part and sticking it again increases, and the work efficiency is slightly lowered. In addition, if the slipperiness is poor, squeegee streaks and scratches are likely to occur when affixing, and it is necessary to work carefully, so work efficiency decreases.

  When the above evaluation criteria is shown as “poor”, if the surface slipperiness is poor, the squeegee does not slide smoothly, and it becomes difficult to remove remaining bubbles and water bubbles. Moreover, when surface slipperiness is bad, a squeegee bites in when sticking, and a streak and a damage | wound easily enter and it becomes easy to produce a malfunction. Moreover, when curved surface followability is bad, bubbles and water bubbles are likely to remain, and defects are likely to occur. In addition, when the curved surface followability is poor, a surplus of material (portion that does not conform to the curved surface) increases.

Example 1
<< Preparation of coating solution for surface protective layer >>
An aqueous urethane polymer (trade name “F-8082D” manufactured by Daiichi Kogyo Co., Ltd.) was prepared as a coating solution for the surface protective layer. In addition, the maximum stress value (100% stress value) in the stretched state of 0% to 100% of the surface protective layer using this coating solution is 24 MPa (catalog value) and is shown in Table 1.

<Formation of surface protective layer>
As the base material layer, a 140-μm thick adipate-ester thermoplastic polyurethane film (manufactured by Nippon Matai Co., Ltd., hardness 86A) was used. On this adipate-based thermoplastic polyurethane film (adipate-based TPU film), the prepared coating solution for the surface protective layer is applied so that the thickness after curing is 10 μm, and dried and cured at a temperature of 80 ° C. for 3 minutes. Then, a surface protective layer was formed on one surface of the base material layer.

<< Production of adhesive layer >>
As a photopolymerization initiator, a mixture of 94 parts of 2-ethylhexyl acrylate and 6 parts of acrylic acid as a monomer component, 0.05 parts of a trade name “Irgacure 651” (manufactured by Ciba Specialty Chemicals) After blending 0.05 parts of the name “Irgacure 184” (manufactured by Ciba Specialty Chemicals), until the viscosity is about 15 Pa · s (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) An acrylic composition (UV syrup) partially polymerized by irradiation with ultraviolet rays was prepared.

  To 100 parts of the obtained UV syrup, 0.3 part of hexanediol diacrylate was added to prepare an adhesive composition.

  This pressure-sensitive adhesive composition was applied to a release-treated surface of a 50 μm-thick polyethylene terephthalate film (PET film) as a release liner so that the final product had a thickness of 50 μm.

On top of this, a peel-treated PET film as a separator is overlaid and coated, and then the surface of the PET film is cured by irradiating with ultraviolet rays (illuminance 290 mW / cm ² , light amount 4,600 mJ / cm ² ) using a metal halide lamp. Thus, an adhesive layer was formed on the release liner. Then, it was made to dry at 140 degreeC for 3 minute (s), the unreacted residual acrylic monomer was dried, and the adhesive layer was produced.

<Production of adhesive sheet>
The separator was removed, and the resulting multilayer sheet was bonded to the surface opposite to the surface protective layer side surface (that is, the base material layer surface) using a hand roller so that the adhesive layer overlapped, and the thickness was 200 μm. A multilayer pressure-sensitive adhesive sheet (surface protective layer / base material layer / pressure-sensitive adhesive layer) was produced. In this multilayer adhesive sheet, a release liner is provided on the adhesive layer.

<Measurement and evaluation>
About the obtained multilayer adhesive sheet, according to the evaluation method shown above, the maximum stress value in the stretched state exceeding 0% to 10% was obtained, and the pasting workability was evaluated. Furthermore, the static friction coefficient was measured about the obtained surface protective layer. The results are shown in Tables 1 and 2.

(Example 2)
As shown in Table 1, the surface protective layer coating solution was changed to a water-based urethane polymer (trade name “HUX-401” manufactured by ADEKA Co., Ltd.). A multilayer pressure-sensitive adhesive sheet having a surface protective layer on one side and a pressure-sensitive adhesive layer on the other side was prepared. About the obtained multilayer adhesive sheet and the surface protective layer, the static friction coefficient, the maximum stress value, and the sticking workability were evaluated in the same manner as in Example 1 according to the evaluation method described above. The results are shown in Tables 1 and 2.

(Example 3)
As shown in Table 1, the surface protective layer coating solution was changed to a water-based urethane polymer (trade name “HUX-564” manufactured by ADEKA Corporation). A multilayer pressure-sensitive adhesive sheet having a surface protective layer on one side and a pressure-sensitive adhesive layer on the other side was prepared. About the obtained multilayer adhesive sheet and the surface protective layer, the static friction coefficient, the maximum stress value, and the sticking workability were evaluated in the same manner as in Example 1 according to the evaluation method described above. The results are shown in Tables 1 and 2.

Example 4
As shown in Table 1, the type of coating solution for the surface protective layer was changed to an aqueous urethane polymer (trade name “HUX-232” manufactured by ADEKA Co., Ltd.). A multilayer pressure-sensitive adhesive sheet having a surface protective layer on the surface and a pressure-sensitive adhesive layer on the other surface was produced. About the obtained multilayer adhesive sheet and the surface protective layer, the static friction coefficient, the maximum stress value, and the sticking workability were evaluated in the same manner as in Example 1 according to the evaluation method described above. The results are shown in Tables 1 and 2.

(Comparative Example 1)
The base material was the same as in Example 1 except that the type of coating solution for the surface protective layer was changed to an aqueous urethane polymer (trade name “F-2968D” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as shown in Table 1. A multilayer pressure-sensitive adhesive sheet having a surface protective layer on one side of the layer and a pressure-sensitive adhesive layer on the other side was prepared. About the obtained multilayer adhesive sheet and the surface protective layer, the static friction coefficient, the maximum stress value, and the sticking workability were evaluated in the same manner as in Example 1 according to the evaluation method described above. The results are shown in Tables 1 and 2.

(Comparative Example 2)
A multilayer pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the type of the surface protective layer coating liquid was changed to a fluorine-based coating liquid as shown in Table 1. That is, a 50% solution of fluoroethylene vinyl ether in xylene and toluene (trade name “Lumiflon LF600” manufactured by Asahi Glass Co., Ltd.) and an isocyanate-based crosslinking agent (trade name “Coronate HX” manufactured by Nippon Polyurethane Industry Co., Ltd.) ), 9.49 parts of dibutyltin lauric acid (trade name “OL1” manufactured by Tokyo Fine Chemical Co., Ltd.) as a catalyst, 0.35 part of a xylene diluted solution (solids concentration 0.1%), and a diluent solvent A fluorine-based coating solution was prepared by mixing at a ratio of 76.41 parts of toluene as the fluorine-based surface protective layer on one surface of the base material layer in the same manner as in Example 1. A pressure-sensitive adhesive layer was formed on the other surface to produce a multilayer pressure-sensitive adhesive sheet, and the obtained multilayer pressure-sensitive adhesive sheet was measured in the same manner as in Example 1. The preliminary evaluation was carried out. The results are shown in Table 1 and Table 2.

(Comparative Example 3)
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one surface of the base material layer was produced in the same manner as in Example 1 except that the surface protective layer was not provided. About the obtained adhesive sheet, it carried out similarly to Example 1, and evaluated the static friction coefficient of the base material layer, the maximum stress value, and the sticking workability | operativity according to the evaluation method shown above. The results are shown in Tables 1 and 2.

(Notes in Table 1 and Table 2)
F-8082D: Aqueous urethane polymer (Daiichi Kogyo Seiyaku Co., Ltd.)
HUX-401: Water-based urethane polymer (manufactured by ADEKA Corporation)
HUX-564: Water-based urethane polymer (manufactured by ADEKA Corporation)
HUX-232: Water-based urethane polymer (manufactured by ADEKA Corporation)
F-2968D: Water-based urethane polymer (Daiichi Kogyo Seiyaku Co., Ltd.)
LF600: Fluoroethylene vinyl ether alternating copolymer (Asahi Glass Co., Ltd.)
“Coronate HX”: Isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd.)

  As is clear from Tables 1 and 2, the multilayer adhesive sheets of Examples 1 to 4 of the present invention have smaller maximum stress values up to 0% to 10% than the adhesive sheet of Comparative Example 2. , Found to be excellent in flexibility. From the viewpoint of the effect of flexibility (curved surface followability), the maximum stress value in the stretched state of the surface protective layer from 0% to 100% is preferably 24 MPa or less, more preferably 19 MPa or less, particularly Preferably it is 5 MPa or less.

  Moreover, from Table 1 and Table 2, it turned out that the multilayer adhesive sheet of Examples 1-4 of this invention is excellent in the slipperiness (static friction coefficient) of a surface protective layer compared with Comparative Examples 1 and 3. . From the viewpoint of the effect of surface slipperiness, the maximum stress value in the stretched state of the surface protective layer from 0% to 100% is preferably 5 MPa or more, more preferably 19 MPa or more, and particularly preferably 24 MPa or more. .

  Therefore, in order to satisfy the characteristics of both flexibility (curved surface followability) and surface slipperiness, the maximum stress value in the stretched state of the surface protective layer from 0% to 100% is within a range of 5 MPa or more and 24 MPa or less. It is necessary to adjust in consideration of the balance between flexibility and surface slipperiness.

  That is, according to the present invention, a multilayer pressure-sensitive adhesive sheet excellent in both flexibility and surface slipperiness could be realized.

  The multilayer pressure-sensitive adhesive sheet of the present invention can be suitably used as a multilayer pressure-sensitive adhesive sheet that requires flexibility to a curved surface or the like, and is particularly suitable for an adherend (adherent) having a severe three-dimensional curved surface. It can be used for the application and has excellent workability. For example, it can be used as a pressure-sensitive adhesive sheet or a decorative pressure-sensitive adhesive sheet for protecting a coating film surface exposed to harmful environments including outdoor weather, solvents, dust, fats and oils, and marine environments. Further, it is also suitable as a chipping tape for protecting a coating film of an automobile body or the like, an adhesive sheet for a body protection film, or a multilayer sheet.

Claims (4)

A multilayer pressure-sensitive adhesive sheet having at least a surface protective layer, a base material layer, and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is provided on one surface of the base material layer, and the surface protective layer is the base material Provided on the other surface of the layer, the static friction coefficient of the surface protective layer is 0.05 or more and 1.50 or less, and the maximum stress in a stretched state of 10% exceeding 0% of the multilayer adhesive sheet value 0.5MPa or more, Ri following range der 4.0 MPa, the base layer contains a urethane polymer, said urethane polymer is adipate ester-based thermoplastic polyurethane, polyether-based thermoplastic polyurethane, It is at least one selected from the group consisting of polycarbonate-based thermoplastic polyurethane and polycaprolactone-based thermoplastic polyurethane, and the surface protective layer comprises a urethane-based polymer. Multi-layered adhesive sheet as a component, a urethane-based polymer forming the surface protective layer has a water-based urethane polymer or solvent-based urethane polymer der Rukoto. 2. The multilayer pressure-sensitive adhesive sheet according to claim 1, wherein the surface protective layer has a maximum stress value within a range of 5.0 MPa or more and 24.0 MPa or less in a stretched state exceeding 0% to 100%. The base layer is, the maximum stress value of 0.5MPa or more at up to 10% elongation state greater than 0% to any one of claims 1 or 2, characterized in that in the range of less than 3.5MPa A multilayer pressure-sensitive adhesive sheet as described in 1. The multilayer adhesive sheet according to any one of claims 1 to 3 , wherein the multilayer adhesive sheet is used as a protective sheet for protecting the surface of an adherend.

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