JP2021155632A - Multilayer film - Google Patents

Abstract

To provide a multilayer film which prevents swelling in a thermoplastic polyurethane layer during application of a chemical, and has excellent chemical resistance with no changes in appearance.SOLUTION: A layer adjacent to a surface coat layer of a thermoplastic polyurethane layer in a multilayer film is constituted by a thermoplastic polyurethane which is a reaction product using a hydrogenated xylylene diisocyanate (1,4-H6XDI). When the layer is a single layer, the layer shows a Shore A hardness of 90 to a Shore D hardness of 65; and when the layer is a multilayer, the layer shows the Shore A hardness of 95 to the Shore D hardness of 65. Accordingly, the multilayer film prevents swelling in the thermoplastic polyurethane layer during application of a chemical, and has excellent chemical resistance with no changes in appearance.SELECTED DRAWING: None

Description

The present invention relates to a multilayer film having a thermoplastic polyurethane layer and a surface coating layer.

Adhesive sheets used as paint protective sheets or surface protective sheets to prevent scratches and flying stones on the exterior of vehicles such as automobiles and to prevent deterioration due to the weather are used to protect painted surfaces, headlights, windowpanes, etc. of automobiles. Since it is used, it is necessary to attach it along the strict parts of steps and three-dimensional curved surfaces. For this reason, followability and stretchability are required, and a thermoplastic polyurethane film is often used as a base, and it can be usually defined by the type of polyol such as polyester-based, polycaprolactone-based, and polycarbonate-based.

This polyurethane film is sticky, and when used in an outdoor environment, if dirt such as sand or dust adheres to the surface, the dirt will settle and cannot be removed. Therefore, the above-mentioned protective sheet prevents the surface of the polyurethane film from becoming dirty. It is common to provide a coat layer to form a multilayer film (see, for example, Patent Documents 1 to 6).

Various studies have also been made on this multilayer film. For example, Patent Document 7 proposes to use a high-hardness thermoplastic polyester-based polyurethane for the surface protective layer for the purpose of improving handleability during construction. There is.

Japanese Unexamined Patent Publication No. 2005-272558 Japanese Patent Application Laid-Open No. 2008-539107 Japanese Unexamined Patent Publication No. 2015-98574 JP 2015-52100 Japanese Unexamined Patent Publication No. 2014-166748 Japanese Unexamined Patent Publication No. 2018-53193 JP-A-2019-1015

By the way, chemicals may adhere to the protective sheet attached to the automobile. Specifically, it is a cleaning agent called an engine cleaner or an engine conditioner, and is used not only for cleaning the engine room but also for cleaning various parts such as around wheels. When this chemical adheres to the protective sheet, it penetrates the coat layer and reaches the polyurethane film, and the film may be melted by the chemical or the film may swell and then dry, thereby impairing the appearance.

Therefore, it has been desired that the thermoplastic polyurethane layer does not swell due to permeation when the engine cleaner is dropped onto the surface coat layer, and the appearance does not change.

Here, in Patent Document 7, which refers to a thermoplastic polyurethane film having a multi-layer structure, neither description nor suggestion is made regarding chemical resistance.

Although the chemical resistance is mentioned in Patent Document 3, organic solvents such as gasoline are targeted as chemicals adhering to the surface, and highly soluble chemicals such as dichloromethane, which is a component of engine cleaners, are assumed. It is not mentioned, and there is no mention of changes in appearance when chemicals adhere to it.

An object of the present invention is to provide a multilayer film having excellent chemical resistance.

The present inventor has obtained the following findings as a result of repeated diligent studies in order to solve the above-mentioned problems.

That is, the layer adjacent to the surface coat layer of the thermoplastic polyurethane layer is composed of thermoplastic polyurethane which is a reaction product using _{hydrogenated xylylene diisocyanate (1,4-H 6 XDI), and this layer is a single layer.} In the case of shore A hardness 90 to shore D hardness 65, and in the case of a plurality of layers, shore A hardness 95 to shore D hardness 65, it is found that a multilayer film having excellent chemical resistance can be obtained.

The present invention is based on the findings of the present inventor, and the means for solving the above-mentioned problems are as follows.

<1> A multilayer film having a thermoplastic polyurethane layer and a surface coating layer, wherein the thermoplastic polyurethane layer is composed of a single layer or a plurality of layers, one layer of which is adjacent to the surface coating layer, and a hydrogenated xylylene diisocyanate. When the hardness of this layer, which contains thermoplastic polyurethane which is a reaction product using (1,4-H ₆ XDI) and is measured according to JIS K7311, is composed of a single layer, the shore A hardness is 90 to the shore D hardness. It is a multilayer film having a hardness of 65, and when it is composed of a plurality of layers, it has a shore A hardness of 95 to a shore D hardness of 65.

<2> The multilayer film according to <1>, wherein when the thermoplastic polyurethane layer is composed of a plurality of layers, the thickness of the layer adjacent to the surface coating layer is 5 μm or more.

<3> When the thermoplastic polyurethane layer is composed of a plurality of layers, the thermoplastic polyurethane layer is a reaction product using _{dicyclohexylmethane diisocyanate (H 12 MDI) and a layer adjacent to the surface coat layer.} The multilayer film according to <1> or <2>, which is composed of a layer made of plastic polyurethane.

<4> The multilayer film according to any one of <1> to <3>, wherein the surface coat layer has a urethane bond.

<5> The stress at 10% elongation is 20 N / 25 mm or less, and the load (residual stress) 30 seconds after stopping in the 40% stretched state is 25 N / 25 mm or less. The multilayer film according to any one.

<6> The multilayer film according to any one of <1> to <5>, which has a total light transmittance of 90% or more according to JIS K7361-1.

<7> The multilayer film according to <6>, wherein the total light transmittance according to JIS K7361-1 is 92% or more.

<8> The multilayer film according to any one of <1> to <7>, wherein the haze value according to JIS K7136 is 3.0% or less.

<9> The multilayer film according to <8>, wherein the haze value according to JIS K7136 is 2.0% or less.

<10> The multilayer film according to any one of <1> to <9>, which is used to protect an adherend having a curved surface.

In the multilayer film of the present invention, the layer adjacent to the surface coating layer of the thermoplastic polyurethane layer is composed of thermoplastic polyurethane which is a reaction product using _{hydrogenated xylylene diisocyanate (1,4-H 6 XDI).} In the case of a single layer, the shore A hardness was 90 to shore D hardness 65, and in the case of multiple layers, the shore A hardness was 95 to shore D hardness 65. This makes it possible to improve the chemical resistance.

FIG. 1 is a cross-sectional view showing one form of the layer structure of the multilayer film of the present invention. FIG. 2 is a diagram showing an example of attaching the multilayer film of FIG. 1 to an adherend. FIG. 3 is a diagram showing another example of sticking the multilayer film of FIG. 1 to the adherend. FIG. 4 is a cross-sectional view showing another form of the layer structure of the multilayer film of the present invention. FIG. 5 is a diagram showing an example of attaching the multilayer film of FIG. 4 to an adherend. FIG. 6 is a diagram showing another example of sticking the multilayer film of FIG. 4 to the adherend. FIG. 7 is a photograph showing the result of the engine cleaner resistance evaluation of Example 1. FIG. 8 is a photograph showing the result of the engine cleaner resistance evaluation of Comparative Example 3. FIG. 9 is a photograph showing the result of the workability of attaching to the automobile door mirror of Example 8. FIG. 10 is a photograph showing the result of sticking workability on a coated steel plate having a step in Example 9.

The multilayer film of the present invention has at least a thermoplastic polyurethane layer and a surface coating layer.

FIG. 1 is a diagram showing an example of a layer structure of the multilayer film of the present invention, FIG. 2 is a diagram showing an example of attaching the multilayer film of FIG. 1 to an adherend, and FIG. 3 is a diagram showing an example of sticking the multilayer film to the adherend of FIG. It is a figure which shows the other pasting example. Further, FIG. 4 is a diagram showing another embodiment of the layer structure of the multilayer film of the present invention, FIG. 5 is a diagram showing an example of attaching the multilayer film of FIG. 4 to an adherend, and FIG. 6 is a multilayer of FIG. It is a figure which shows the other example of sticking a film to an adherend.

The multilayer film 10 shown in FIG. 1 is composed of a central thermoplastic polyurethane layer 11 and a surface coat layer 12 formed so as to be adjacent to the surface thereof.

When the multilayer film 10 is attached to the object to be protected, the thermoplastic polyurethane layer 11 and the surface coating layer 12 are used as base materials, and as shown in FIG. 2, the thermoplastic polyurethane surface on the opposite surface without the surface coating layer is used. The adhesive layer 13 is provided on the surface and is attached to the adherend a. As a result, it is used to prevent scratches and deterioration of objects to be protected such as painted surfaces of automobiles, headlights, and exterior parts of vehicles such as window glass.

Further, in the multilayer film 10, since polyurethane is thermoplastic and adhesiveness can be obtained by heat melting, as shown in FIG. 3, the multilayer film 10 is directly heat-melted on the adherend a without providing an adhesive layer. It can also be pasted and used.

On the other hand, in the multilayer film 20 shown in FIG. 4, the central thermoplastic polyurethane layer 21 has a two-layer structure in which the first polyurethane layer 22 and the second polyurethane layer 23 are arranged in this order from the side adjacent to the surface coating layer 12. It has become.

In the multilayer film 20, by forming the thermoplastic polyurethane layer 21 into a two-layer structure, the second polyurethane layer 23 can improve the sticking workability of the first polyurethane layer 22. The surface coating layer 12 is formed on the surface of the thermoplastic polyurethane layer 21 as in the multilayer film 10 of FIG.

Further, in the multilayer film 20, as in the multilayer film 10 of FIG. 1, as shown in FIG. 5, the adhesive layer 13 is provided on the thermoplastic polyurethane surface on the opposite surface without the surface coating layer, and the object to be protected is adhered to the multilayer film 20. It is used by being attached to the body a, and as shown in FIG. 6, it can also be used by being directly attached to the adherend a while being thermally melted without providing an adhesive layer.

Next, the components of each layer constituting the multilayer film of the present invention will be described.

<Thermoplastic polyurethane layer>
In the present invention, the thermoplastic polyurethane means a block copolymer obtained by polymerizing a polyisocyanate with a chain extender and a polyol, and the thermoplastic polyurethane layer is a monolayer made of thermoplastic polyurethane or a monolayer made of thermoplastic polyurethane. It means a laminated body composed of a plurality of layers.

In the present invention, heat is a reaction product using hydrogenated xylylene diisocyanate (hereinafter, also referred to as “1,4-H _{6 XDI”) which is an alicyclic isocyanate as a component constituting the thermoplastic polyurethane layer.} By using a plastic polyurethane (hereinafter, also referred to as "1,4-H ₆ XDI-TPU"), a film having excellent chemical resistance can be obtained.

The polyisocyanate component of the _1,4-H 6 XDI-TPU for use in this _invention are preferably configured from only 1,4-H 6 XDI-TPU, in effect is not impaired range of the present invention , Other polyisocyanates can be included as a polymerization component.

_{The polyisocyanate of thermoplastic polyurethane is not particularly limited as long as 1,4-H 6} XDI is contained as a main component in the layer adjacent to the surface coating layer, and for example, aliphatic diisocyanate, alicyclic diisocyanate, poly. Examples thereof include isocyanate group-terminated compounds produced by the reaction of isocyanates with active hydrogen group-containing compounds, polyisocyanate modified products produced by the reaction of polyisocyanates, and polyisocyanates partially stabilized with a blocking agent having one active hydrogen in the molecule. Examples of the aliphatic diisocyanate include hexamethylene diisocyanate, dodecane diisocyanate, and trimethyl-hexamethylene diisocyanate. Examples of the alicyclic diisocyanate include cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane-diisocyanate methyl and the like. Examples of the reaction of polyisocyanate include a carbodiimidization reaction. Examples of the blocking agent having one active hydrogen in the molecule include methanol, n-butanol, benzyl alcohol, ethyl acetoacetate, ε-caprolactam, methylethylketone oxime, phenol, cresol and the like.

The chain extender of the thermoplastic polyurethane is not particularly limited, and examples thereof include compounds having a molecular weight of 500 or less. Examples of such compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,9-nonanediol, and 2-methyl-1,3-. Propylenediol, 3-methyl-1,5-pentanediol, neopentyl glycol, N-phenyldiisopropanolamine, monoethanolamine, dipropylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6 Examples thereof include −hexanediol and 1,4-bis (2-hydroxyethoxy) benzene.

The polyol of the thermoplastic polyurethane is not particularly limited as long as it is a compound having two hydroxyl groups in one molecule and having a molecular weight of about 200 to 10,000, and examples thereof include polyether diols, polyester diols, and polycarbonate diols.

Specific examples of the polyether diol include polyethylene glycol, polypropylene glycol (PPG), a copolymer of ethylene oxide and propylene oxide, and polytetramethylene glycol (PTMG).

Examples of polyester diols include poly (ethylene adipate) diol, poly (propylene adipate) diol, poly (butylene adipate) diol (PBA), poly (hexamethylene adipate) diol, poly (butylene isophthalate) diol, and poly-ε-caprolactone. Examples include diol (PCL).

Examples of the polycarbonate diol include a polyhexamethylene carbonate diol (PHC), a cocondensate of the polyhexamethylene carbonate diol and another polyester diol, a polyether diol, and a polyether ester diol. In addition, these may be used individually by 1 type, and may combine 2 or more types.

The thermoplastic polyurethane is synthesized by a known method such as a one-shot method or a prepolymer method, and can be produced in pellet form by a known method such as a batch reaction method or a continuous reaction method.

As a commercially available product of the 1,4-H ₆ XDI-TPU, for example, the trade name "Fortimo (registered trademark)" series manufactured by Mitsui Chemicals, Inc. can be used.

In the case of a single layer, the hardness of the thermoplastic polyurethane film is preferably Shore A hardness 90 to Shore D hardness 65, and Shore A hardness 95 to Shore D hardness 60. In the case of a plurality of layers, the shore A hardness of the layer containing the thermoplastic polyurethane reaction-generated using _{1,4-H 6 XDI is 95 to shore D hardness 65.} If the shore A hardness is less than 90 in the case of a single layer, or if the shore A hardness is less than 95 in the case of multiple layers, the chemicals permeate due to dropping of chemicals such as a cleaning agent when the multilayer film is formed. The appearance changes and it becomes difficult to obtain the desired chemical resistance. On the other hand, when the shore D hardness is larger than 65, the load (residual stress) 30 seconds after the film is stopped with the film stretched by 40% and the stress value with the film stretched by 10% become high, and the multilayer film The film may be hard and the curved surface followability may not be obtained at the time of sticking when the film is manufactured.

When the thermoplastic polyurethane film has a plurality of layers, the film is thinner than the case of a single layer, so that it becomes easier for chemicals to permeate, and therefore it is desired to have more excellent chemical resistance. It is considered that the reason why the plurality of layers are required to have higher hardness than that of the single layer is that the amount of hard segments derived from the diisocyanate component is increased, so that the hardness is increased and the chemical resistance is excellent. The shore A hardness is a standard for measuring the hardness of general rubber, and the shore D hardness is a similar standard for high-hardness rubber exceeding the shore A hardness of 95. Both are durometers (spring type rubber hardness meters). Can be measured according to JIS K7311.

When the thermoplastic polyurethane layer _{contains only 1,4-H 6 XDI-TPU, that is, 100% by mass of 1,4-H 6} XDI-TPU excluding trace components such as impurities and additives, the rubber elastic property is exhibited. It can be strong. Therefore, in order to improve the sticking workability to the adherend having a step or a three-dimensional curved surface, a multi-layer structure may be formed with a resin having excellent sticking workability as long as the chemical resistance is not impaired. It may be mixed. In the case of a multi-layer structure with the resin having excellent sticking workability, the layer of the resin having excellent sticking workability corresponds to the second polyurethane layer 23 shown in FIG.

As a resin having excellent sticking workability, a thermoplastic polyurethane (hereinafter referred to as "H ₁₂ MDI-TPU") reaction-generated using dicyclohexylmethane diisocyanate is preferably mentioned.

Commercially available products of H ₁₂ MDI-TPU include, for example, the trade name "ESTANE (registered trademark)" series of Lubrizol, the "Elastran (registered trademark)" series of BASF Japan, and Huntsman. Product name "KRYSTALGRAN" series and the like can be used.

When the thermoplastic polyurethane layer is formed into a plurality of layers, the 1,4-H ₆ XDI-TPU layer adjacent to the surface coat layer is preferably 5 μm or more, and more preferably 10 μm or more. If it is less than 5 μm, the chemical resistance may not be excellent.

In the case of this manner a plurality of _layers, the layer containing 1,4-H 6 XDI-TPU, except for component traces, such as impurities or _additives, only 1,4-H 6 XDI-TPU, i.e. It is preferable to contain 100% by mass of HDI-TPU.

Here, the thickness of the thermoplastic polyurethane layer can be measured according to JIS K7130 using a commercially available film thickness measuring device. Further, the thickness of each layer can be measured, for example, by observing three points (both ends and the central portion) of the cross section with a microscope.

When mixed with a resin with excellent _{sticking workability, the mixing ratio of 1,4-H 6} XDI-TPU and the resin with excellent sticking workability by mass is usually 1,4-H ₆ XDI-, which is higher than 3: 7. There are many TPUs, preferably 4: 6 or more, and more preferably 5: 5 or more. That is, 1,4-H ₆ XDI-TPU is contained in the thermoplastic polyurethane layer in an amount of more than 30% by mass, preferably 40% by mass or more, and more preferably 50% by mass or more. When 1,4-H ₆ XDI-TPU is contained in an amount of 50% by mass or more, the chemical resistance can be extremely excellent.

The thermoplastic polyurethane layer can be formed in either a single layer or a plurality of layers by a known method such as a T die casting molding method, a T die nip molding method, an inflation molding method, a calendar molding method, and the like. The T-die nip method is preferable.

Further, in the case of a multi-layer structure with a resin having excellent sticking workability, a method of directly laminating such as coextrusion molding, heat fusion and extrusion laminating, or indirectly using an adhesive such as dry laminating. The method of laminating can be appropriately selected. Among these, it is preferable to coextrude a plurality of resin layers from the T die to form a film having a plurality of layers.

When the thermoplastic polyurethane layer is formed by the T-die nip method, a film-like (or sheet-like) separator is attached to one or both sides of the molten thermoplastic polyurethane extruded from the flat die and passed through a cooling roll. Can be manufactured.

Examples of the material for forming the separator include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyimide (PI), polyetheretherketone (PEEK), and paper. And so on.

The thermoplastic polyurethane layer is usually obtained by laminating a molten thermoplastic polyurethane on a separator once, and then peeling off the separator after the thermoplastic polyurethane is cooled and cured. When the separator cannot be easily peeled off from the laminated film of these separators and the thermoplastic polyurethane, it is preferable to use one in which the surface of the separator is further peeled off. Examples of the peeling treatment method include a method of coating a peeling agent such as silicone-based, fluorine-based, acrylic-based, melamine-based, and alkyd-based, and a method of laminating a polyolefin-based resin such as polyethylene or polypropylene. In particular, a film made of polyethylene terephthalate whose surface is treated with a release agent is preferably used as a separator.

When a film-forming resin composition or adhesive for forming a surface coat layer is applied to the thermoplastic polyurethane layer in a subsequent step, if a silicone-based release agent is used, the release agent is transferred to the surface of the thermoplastic polyurethane layer. Therefore, a non-silicone-based release agent is preferable because it may hinder the adhesion or adhesion between the thermoplastic polyurethane layer and the adherend as well as components such as an adhesive.

The thickness of the thermoplastic polyurethane layer is not particularly limited, but in both the single layer and the plurality of layers, the total thickness of all the layers is usually 50 to 500 μm, preferably 100 to 300 μm, and more preferably 100 to 300 μm. It is 100 to 200 μm. If it is thinner than 50 μm, it will be difficult to handle when pasting, and there is a risk that it will be easily scratched by flying stones. If it is thicker than 500 μm, it may be difficult to attach it, and it may not be possible to obtain followability to a step or a three-dimensional curved surface.

The optical properties of the thermoplastic polyurethane layer are such that the total light transmittance is 90% or more, preferably 92% or more, so as not to affect the visibility of the object to be protected when the multilayer film is formed. The haze value is 3.0% or less, preferably 2.0% or less. If the total light transmittance is less than 90% and the haze value is larger than 3.0%, it may appear whitish when attached to a glossy painted surface such as an automobile. The total light transmittance and the haze value can be measured by using a haze meter, the total light transmittance can be measured according to JIS K7361-1, and the haze value can be measured according to JIS K7136.

The stress value of the thermoplastic polyurethane layer in a state where the film is stretched by 10% under the temperature condition of 23 ° C. ± 2 ° C. is preferably 20 N / 25 mm or less, and more preferably 15 N / 25 mm or less. preferable. If this stress value is larger than 20 N / 25 mm, the film may be hard, difficult to stretch, wrinkled, and the sticking workability may be deteriorated.

Further, the thermoplastic polyurethane layer usually has a load (residual stress) of 25 N / 25 mm or less 30 seconds after stopping in a state of being stretched by 40% under a temperature condition of 23 ° C. ± 2 ° C., and is 20 N / 25 mm or less is preferable, and 16 N / 25 mm or less is more preferable. When making a multilayer film and attaching it to a step or three-dimensional curved surface, after attaching a part to the adherend, stretch the film with one hand and follow the step or three-dimensional curved surface, and hold it in the other hand. The adherend and the film are brought into close contact with each other by a squeegee. At this time, if the residual stress is larger than 25 N / 25 mm, the force to pull back the film at the time of sticking is large, and it is difficult to fix the position in the state where the film is stretched with one hand, or glue slippage occurs. , May be difficult to handle.

These stresses can be measured, for example, by cutting a sample into an appropriate size and stretching it to a predetermined length with a commercially available tensile tester.

Further, the thermoplastic polyurethane layer preferably contains an ultraviolet absorber. By including the ultraviolet absorber, it is possible to reduce the deterioration of the polyurethane layer when used outdoors and the deterioration of the adhesive when used by applying an adhesive or the like.

The ultraviolet absorber is not particularly limited as long as it is conventionally known, but for example, benzotriazole-based, triazine-based, and benzophenone-based ones are preferable.

Examples of the benzotriazol system include 2- (2'-hydroxy-5'-methylphenyl) benzotriazol and 2- (2'-hydroxy-5'-methylphenyl) -5,6-dichlorobenzotri. Azol), 2- (2'-hydroxy-5'-t-butylphenyl), benzotriazol, 2- (2'-hydroxy-3'-methyl-5'-t-butylphenyl) benzotriazol , 2- (2'-Hydroxy-3', 5'-di-t-butylphenyl) -5-chloro-benzotriazol, 2- (2'-hydroxy-5'-phenylphenyl) -5-chlorbenzo Triazol, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) -5-chlorolobenzotriazol, 2- (2'-hydroxy-3'-t- Butyl-5'-methylphenyl) -5-chlorobenzotriazol, 2- (2'-hydroxy-3', 5'-di-t-amylphenyl) benzotriazol, 2- (2'-hydroxy) -3', 5'-di-t-butylphenyl) benzotriazol, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazol, 2- {2'-hydroxy-3'-( 3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidemethyl) -5'-methylphenyl} benzotriazol, 2- {2-hydroxy-3,5-bis (α, α'-dimethylbenzyl) phenyl} Examples thereof include -2-hydroxybenzotriazol and the like, and mixtures, modified products, polymers and derivatives thereof.

Examples of the triazine system include 2- (4,6-diphenyl-1,3,5-triazine-2-yl) -5-[(hexyl) oxy] -phenol and 2- [4-[(2-hydroxy). -3-Dodecyloxypropyl) Oxy] -2-Hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-Hydroxy-3) -Tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4 dimethylphenyl) -1,3,5-triazine, 2,4-bis (2,4-dimethylphenyl)- Examples thereof include 6- (2-hydroxy-4-iso-octyloxyphenyl) -s-triazine and the like, mixtures thereof, modified products, polymers and derivatives thereof.

Examples of the benzophenone system include 2,3'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone and the like. Be done.

Further, in the thermoplastic polyurethane film, it is preferable to use a light stabilizer or an antioxidant in combination with these ultraviolet absorbers.

Examples of the light stabilizer include poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6). 6-Tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], dimethyl-1- (2-hydroxyethyl) -4-hydroxy succinate Examples thereof include hindered amine-based photostabilizers such as −2,2,6,6-tetramethylpiperidine polycondensate and bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate.

As the antioxidant, a phenol-based antioxidant, a phosphoric acid-based antioxidant, a sulfur-based antioxidant, etc. can be used. Examples include phenol-based antioxidants, phosphorus-based antioxidants manufactured by ADEKA Corporation, trade name ADEKA STAB PEP8, and the like.

The thermoplastic polyurethane layer has a light transmittance of 25% or less for wavelengths of 300 to 380 nm calculated in accordance with JIS S3107 based on data measured by a self-recording spectrophotometer in accordance with JIS R3106. It is preferably 15% or less, and more preferably 10% or less. As a film for agriculture that needs to block ultraviolet rays by suppressing the transmission of light rays in the ultraviolet region in this way, and as a film for preventing various damages caused by birds and animals that can see ultraviolet rays. , Can be used.

<Surface coat layer>
The surface coat layer in the present invention usually contains a urethane bond in the main chain. By containing the urethane bond, the surface coat layer can easily follow the elongation of the thermoplastic polyurethane layer when it is attached to a step or a three-dimensional curved surface, and cracks in the surface coat layer when the film is elongated can be prevented. Can be prevented.

The stretchability of the surface coat layer can be confirmed by stretching the multilayer film. Specifically, when a multilayer film obtained by forming a surface coat layer on a thermoplastic polyurethane layer is cut out in a strip shape and then fixed to a tensile tester and stretched, cracks may occur in the surface coat layer. It is visually recognized. The elongation rate at which cracks begin to form in the surface coat layer is defined as the crack elongation of the surface coat layer. The crack elongation of the surface coat layer is not particularly limited, but is usually 60% or more, preferably 80% or more, and more preferably 100% or more.

The film-forming resin composition used for the surface coating layer is not particularly limited as long as it contains a urethane bond, but a two-component curing type obtained by mixing a polyisocyanate compound and a polyol compound at the time of use is preferable, and a thermosetting type is preferable. The curable type is more preferable.

Examples of the polyisocyanate compound include aliphatic diisocyanates, cyclic aliphatic diisocyanates, and trifunctional or higher functional isocyanate compounds. Examples of the aliphatic diisocyanate include lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate. Examples of the cyclic aliphatic diisocyanate include hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4- (or 2,6) -diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), and 1,3- ( Isocyanatomethyl) cyclohexane and the like. Examples of trifunctional or higher functional substances include lysine triisocyanate and the like.

In addition, examples of the polyisocyanate compound include isocyanate multimers such as so-called isocyanurates, biurets, adducts, and allophanates, and those obtained by adding an isocyanate compound to a polyhydric alcohol or a low molecular weight polyester resin.

The polyisocyanate compound may be in the form of so-called blocked isocyanate as long as it reacts with the diol.

The polyol compound is preferably at least one selected from the group consisting of polycaprolactone polyols, polycaprolactone polyols, polycarbonate polyols, polyester polyols, polyether polyols, acrylic polyols and fluorine polyols.

In addition, block polymers obtained by copolymerizing a polyol compound with a fluorine component, a silicone component, etc., a graft polymer in which a fluorine component, a silicone component, etc. are bonded as side chains, and a block graft polymer obtained by combining them also form a film. It is mentioned as a resin composition for use.

An ultraviolet absorber, a light stabilizer, and an antioxidant similar to those of the thermoplastic polyurethane layer can be appropriately added to the film-forming resin composition used for the surface coat layer.

Commercially available products of the coating film forming resin composition used for the surface coating layer are, for example, commercially available from Dainichiseika Kogyo Co., Ltd., Tokushiki Co., Ltd., Arakawa Chemical Industry Co., Ltd. and the like.

The surface coat layer is known by diluting the film-forming resin composition with a solvent or water as appropriate before coating to adjust the viscosity, applying the resin composition to the surface of the thermoplastic polyurethane layer, and then drying the solvent or water. It can be cured by the method.

The diluting solvent is not particularly limited, and examples thereof include methyl isobutyl ketone (MIBK), ethyl acetate, butyl acetate, methyl ethyl ketone (MEK), and toluene.

Examples of the curing method include thermosetting, photocuring, electron beam curing, moisture curing, and oxidative curing. Here, as the photocuring, UV curing which is cured by ultraviolet rays is also possible, but when it is used outdoors, it is necessary to use a weather resistant agent such as an ultraviolet absorber, and its use may be restricted. Therefore, among these, thermosetting in which a crosslinked structure is formed and cured by heating is particularly preferable.

The method of application is not particularly limited, and for example, known coating methods such as bar coater, spray coater, air knife coater, kiss roll coater, metering bar coater, gravure roll coater, reverse roll coater, dip coater, and die coater. It can be applied using an apparatus. Further, the drying method is not particularly limited, and for example, a known drying technique for film coating can be appropriately used.

The temperature and time of thermosetting may be appropriately set as long as the thermoplastic polyurethane layer is not deformed. The temperature is, for example, 40 to 120 ° C., and the time is, for example, 10 minutes to 1 week. Examples of the thermosetting method include hot air, a drying furnace (dryer) of a known coating machine, and an aging room.

The thickness of the surface coat layer is not particularly limited, but is preferably 3 to 50 μm, more preferably 5 to 20 μm. If the thickness is less than 3 μm, the surface coat layer may not obtain the desired performance, and if it is thicker than 50 μm, the surface coat will be stretched on the thermoplastic polyurethane layer when it is applied to a step or a three-dimensional curved surface. The layers may not follow and the surface coat layer may crack.

For the purpose of protecting the surface coat layer and imparting smoothness to the surface of the surface coat layer, the surface coat layer is coated with the film-forming resin composition constituting the surface coat layer, and then the film-forming resin composition is applied. It is preferable that a film-like (or sheet-like) separator is attached to the surface of the object.

Examples of the material for forming the separator include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyimide (PI), polyetheretherketone (PEEK), and paper. And so on.

As the separator, it is preferable to use one in which the surface of a film made of the above-mentioned material is further peeled off. Examples of the peeling treatment method include a method of coating a peeling agent such as silicone-based, fluorine-based, acrylic-based, melamine-based, and alkyd-based, and a method of laminating a polyolefin-based resin such as polyethylene or polypropylene. In particular, a film made of polyethylene terephthalate whose surface is treated with a release agent is preferably used as a separator.

The separator preferably has a smooth surface. The surface roughness Ra (arithmetic mean roughness) of the surface adjacent to the surface coat layer of the separator is preferably 20 nm or less, and more preferably 15 nm or less. If the surface roughness Ra is larger than 20 nm, it may appear whitish when attached to a glossy painted surface such as an automobile. Further, whether or not it looks whitish after pasting can be evaluated not only by visual evaluation but also by reflection haze. The reflection haze can be measured with a surface analyzer "Rhopoint IQ-S" manufactured by Konica Minolta Japan Co., Ltd. or the like. The reflection haze is preferably 2.0% or less, more preferably 1.5% or less.

<Adhesive layer>
When the adhesive layer is provided and used, a known adhesive can be used. As the pressure-sensitive adhesive, for example, general ones such as an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and a urethane-based pressure-sensitive adhesive can be used. Among these, an acrylic pressure-sensitive adhesive capable of exhibiting suitable adhesive strength, durability and the like is preferable.

In addition to the above-mentioned components, the thermoplastic polyurethane layer, the surface coating layer, and the adhesive layer may include, for example, flame retardants, heat improvers, plasticizers, lubricants, antistatic agents, conductivity-imparting agents, colorants, inorganic substances, and the like. Materials that can be usually added to the above-mentioned components, such as organic fillers, fiber-based reinforcing agents, and reaction retardants, may be added within a range that does not affect the physical properties.

The obtained multilayer film has a stress of 20 N / 25 mm or less at 10% elongation, and a load (residual stress) of 25 N / 25 mm or less 30 seconds after stopping in a 40% stretched state. preferable. When the stress at 10% elongation is 20 N / 25 mm or less, and the load (residual stress) 30 seconds after stopping in the 40% stretched state is 25 N / 25 mm or less, the thermoplastic polyurethane layer has appropriate stretchability. In addition, the surface coat layer has good followability to the thermoplastic polyurethane layer, and the workability of sticking to the object to be protected can be improved.

Further, as for the optical properties of the obtained multilayer film, the total light transmittance is 90% or more, preferably 92% or more, and the haze value is 3.0% or less, as in the thermoplastic polyurethane layer. 0% or less is preferable.

The multilayer film of the present invention _{has excellent chemical resistance by using 1,4-H 6} XDI-TPU for the thermoplastic polyurethane layer, and can prevent a change in appearance and a decrease in adhesive strength. Further, by having the surface coat layer containing the urethane bond, appropriate stretchability can be obtained, the followability to the thermoplastic polyurethane layer is improved, and the coating on the object to be protected can be smoothly performed.

Therefore, the multilayer film of the present invention is attached not only to a paint protective sheet or a surface protective sheet to prevent scratches and flying stones on the exterior of a vehicle such as an automobile and to prevent deterioration due to the weather, but also to a curved surface such as a flexible liquid crystal. It can be widely used to protect an adherend having a step or a three-dimensional curved surface, such as a film that protects a screen.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

Verification 1. Physical characteristics when the thermoplastic polyurethane layer is a single layer First, the present inventor generated a reaction using _{1,4-H 6 XDI when the thermoplastic polyurethane layer was a single layer (see FIG. 1).} It was verified as follows how the physical properties change depending on the hardness of the thermoplastic polyurethane layer.

(Example 1)
A thermoplastic polyurethane reacted by copolymerization of hydrogenated xylylene diisocyanate as a polyisocyanate component (hereinafter, also referred to as "1,4-H ₆ XDI") and a polycarbonate polyol as a polyol component is supplied to an extruder. After melting and kneading, it was extruded from a T-die attached to the tip of the extruder. Nip in a state where both sides are sandwiched between polyethylene terephthalate (hereinafter referred to as "PET") film as a separator, and a layered thermoplastic polyurethane (hereinafter also referred to as "TPU") film (thermoplastic) having a thickness of 150 μm. Polyurethane layer) was prepared.

From this produced thermoplastic polyurethane film, the PET film was peeled off on both sides, and the hardness, stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane film were measured as follows. The results are shown in Table 1.

On the other hand, as a coating liquid of the resin composition for forming a film of the surface coat layer, a fluorine-modified acrylic polyol (solid content 35%), an isocyanate-based curing agent (solid content 60%), and ethyl acetate as a diluting solvent are added. A coating liquid of fluorine-modified acrylic urethane resin A blended in a mass fraction of 39:19:42 was prepared.

The PET film on one side of the prepared TPU layer was peeled off from this coating liquid for the surface coating layer and applied so that the thickness after drying was 10 μm to prepare the multilayer film of Example 1 and tolerated as follows. The engine cleaner resistance as an index of chemical properties was evaluated. The results are shown in Table 1.

[Measurement of each physical property]
<Hardness>
It was measured according to JIS K7311 using a durometer (spring type rubber hardness tester).

<Stress relaxation>
The measurement sample was cut into a width of 25 mm and a length of 150 mm, and fixed to a tensile tester (Autograph AG-X: manufactured by Shimadzu Corporation) so that the distance between the chucks was 100 mm. Then, under the temperature condition of 23 ° C. ± 2 ° C., the material was pulled at a speed of 200 mm / min, and the distance between the chucks became 140 mm, which was extended by 40% (1.4 times the initial length). The load (residual stress) after 30 seconds from the stop was measured in N units.

<Tensile characteristics>
The measurement sample was cut into a width of 25 mm and a length of 100 mm, and fixed to a tensile tester (Autograph AG-X: manufactured by Shimadzu Corporation) so that the distance between the chucks was 50 mm. Subsequently, under a temperature condition of 23 ° C. ± 2 ° C., the stress in a state of being pulled at a speed of 300 mm / min and stretched by 10% was measured in N units.

<Optical characteristics>
Using a haze meter (NDH7000: manufactured by Nippon Denshoku Kogyo Co., Ltd.), the total light transmittance (%) is measured according to JIS K7361-1: 1997, and the haze value (%) is measured according to JIS K7136: 2000. ) Was measured.

<Engine cleaner resistance>
Dichloromethane and methanol were weighed in the same volume with a measuring cylinder and prepared as an engine cleaner, which was used as a mixed solution for a chemical resistance test. After dropping only one drop of this mixed solution onto the surface coat layer of the measurement sample, the mixture was allowed to stand until 5 seconds and 60 seconds had elapsed, respectively. After that, the dropping surface was wiped off with a paper cloth, and it was visually confirmed whether there was any abnormality in the appearance. The evaluation criteria are as follows.
◯: No change in appearance after 60 seconds.
Δ: The appearance does not change after 5 seconds, but the appearance changes whitish after 60 seconds.
X: After 5 seconds, the appearance changes to whitish.
As an example, a photograph of the result of Example 1 is shown in FIG.

(Example 2)
The thermoplastic polyurethane film (thermoplastic polyurethane layer) and the multilayer film of Example 2 were produced in the same manner as in Example 1 except that the polyol component was polycaprolactone polyol in Example 1. In the same manner as in Example 1, the hardness, stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 1.

(Example 3 and Comparative Example 1)
A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Example 1 except that the thermoplastic polyurethane resins having different hardness were used in Example 1. In the same manner as in Example 1, the hardness, stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 1.

(Comparative Example 2)
In Comparative Example 1, the thermoplastic polyurethane film (thermoplastic polyurethane layer) and the multilayer film of Comparative Example 2 were produced in the same manner as in Comparative Example 1 except that the polyol component was a polyether polyol. In the same manner as in Example 1, the hardness, stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 1.

As is clear from the results in Table 1, in the multilayer film composed of the reaction product using the thermoplastic polyurethane layer having a shore A hardness of 90 or more according to Examples 1 to 3 of the present invention, the engine cleaner is dropped on the surface coat layer. Even so, this did not swell the thermoplastic polyurethane layer, did not change the appearance, and was excellent in chemical resistance (see FIG. 7). On the other hand, in the multilayer film made of the reaction product using the thermoplastic polyurethane layer having a hardness of less than 90 in the comparative example, the engine cleaner swells the thermoplastic polyurethane layer and the appearance changes to whitish, resulting in chemical resistance. Was inferior to. From this, when the thermoplastic polyurethane layer is a single layer, in order to improve the chemical resistance, the hardness of the thermoplastic polyurethane layer reaction-generated using _{1,4-H 6 XDI is the Shore A hardness.} It was found that it is preferable that the shore A hardness is 90 or more and the shore A hardness is 95 or more. Regarding the optical characteristics, the total light transmittance was 92% or more and the haze value was 2.0% or less, and all the examples were good.

On the other hand, there were cases where the value indicating the stress relaxation property of the thermoplastic polyurethane layer was 25 N / 25 mm or more and the value indicating the tensile property was 20 N / 25 mm or more. Mareta.

Verification 2. Physical properties when the thermoplastic polyurethane layer is a plurality of layers Next, the present inventor has made the thermoplastic polyurethane layer 1,4-H ₆ XDI- in order to obtain good results not only in chemical resistance but also in sticking workability. _{Multiple layers consisting of a layer made of TPU and a layer made of H 12} MDI-TPU, which is a thermoplastic polyurethane having excellent sticking workability (see FIG. 4), and how the physical properties are changed when the thickness of the layer is changed. Was verified to see if it changed.

(Example 4)
_{The thermoplastic polyurethane reacted by copolymerization of 1,4-H 6} XDI as a polyisocyanate component and a polycarbonate polyol as a polyol component was supplied to an extruder, melted and kneaded, and then attached to the tip of the extruder. Extruded from the T die. One side of the film is sandwiched between PET film and the other side is sandwiched between matte biaxially stretched polypropylene (hereinafter referred to as "OPP") film, and the nip is inserted to form a layered thermoplastic polyurethane film with a thickness of 25 μm (No. 1). 1 Thermoplastic Polyurethane Layer) was obtained. The obtained thermoplastic polyurethane film was cured for about one day, and only the OPP film was peeled off.

And H _{12 MDI} as the polyisocyanate component, supplying a thermoplastic polyurethane produced reaction by copolymerization with polycaprolactone polyol as the polyol component in an extruder, melted and kneaded, from a T-die attached to the tip of the extruder Extruded to a thickness of 125 μm (second thermoplastic polyurethane layer). Nip in a state where one side is sandwiched between a PET film and the other side is sandwiched between the thermoplastic polyurethane film corresponding to the first thermoplastic polyurethane layer described above, and the total thickness of the thermoplastic polyurethane film is 150 μm (thermoplastic polyurethane). Layer) was made. The composition of the produced thermoplastic polyurethane film is PET / 1,4-H ₆ XDI-TPU 25 μm / H ₁₂ MDI-TPU 125 μm / PET (the symbol “/” indicates an interlayer, and PET and TPU are It can be peeled off by hand.) In this state, the first thermoplastic polyurethane layer is made of 100% by mass 1,4-H ₆ XDI-TPU.

The thickness of the 1,4-H ₆ XDI-TPU layer before lamination and the thermoplastic polyurethane film (1,4-H ₆ XDI-TPU 25 μm / H ₁₂ MDI-TPU 125 μm) after lamination is Ozaki Co., Ltd. It was measured according to JIS K7130 using a constant pressure thickness measuring device "FFA-1 1.25N" manufactured by Mfg. Co., Ltd. Specifically, in the obtained film having a width of 300 mm, an average value calculated by measuring 10 points in the width direction was adopted.

The PET film was peeled off from the produced thermoplastic polyurethane film, and the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane film were measured in the same manner as in Example 1. The results are shown in Table 2. Regarding the hardness of the first thermoplastic polyurethane layer in the table, the values measured in Verification 1 are described (the same applies to the subsequent Examples and Comparative Examples).

_{Further, the PET film on the 1,4-H 6} XDI-TPU side of the produced thermoplastic polyurethane layer was peeled off, and the fluorine-modified acrylic urethane resin A of Example 1 was applied _{to the 1,4-H 6 XDI-TPU surface.} The liquid was applied so as to have a thickness of 10 μm after drying to prepare a multilayer film of Example 4. The cross section of this multilayer film was observed with a microscope (Digital Microscope VHX-6000 manufactured by KEYENCE CORPORATION), and _{it was confirmed that the 1,4-H 6} XDI-TPU layer was 25 μm. The engine cleaner resistance was evaluated in the vicinity of the cut-out section in the same manner as in Example 1. The results are shown in Table 2.

(Example 5)
In Example 4, the thickness of the 1,4-H ₆ XDI-TPU layer of the first thermoplastic polyurethane layer is 20 μm, while the thickness of the H ₁₂ MDI-TPU layer of the second thermoplastic polyurethane layer. A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Example 4 except that the thickness was set to 130 μm. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 2.

(Example 6)
In Example 4, the thickness of the 1,4-H ₆ XDI-TPU layer of the first thermoplastic polyurethane layer is 15 μm, while the thickness of the H ₁₂ MDI-TPU layer of the second thermoplastic polyurethane layer. A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Example 4 except that the thickness was 135 μm. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 2.

(Example 7)
In Example 4, the thickness of the 1,4-H ₆ XDI-TPU layer of the first thermoplastic polyurethane layer is 10 μm, while the thickness of the H ₁₂ MDI-TPU layer of the second thermoplastic polyurethane layer. A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Example 4 except that the size was 140 μm. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 2.

(Comparative Example 3)
In Example 4, the thermoplastic polyurethane film (thermoplastic polyurethane layer) and the multilayer film of Comparative Example 3 were used in the same manner as in Example 4 except that the polyol component of the first thermoplastic polyurethane layer was polycaprolactone polyol. Made. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 3. Further, FIG. 8 shows a photograph of the results after the evaluation of engine cleaner resistance.

(Comparative Example 4)
In Comparative Example 3, the thickness of the 1,4-H ₆ XDI-TPU layer of the first thermoplastic polyurethane layer is 20 μm, while the thickness of the H ₁₂ MDI-TPU layer of the second thermoplastic polyurethane layer. A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Comparative Example 3 except that the thickness was set to 130 μm. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 3.

(Comparative Example 5)
In Comparative Example 3, the thickness of the 1,4-H ₆ XDI-TPU layer of the first thermoplastic polyurethane layer is 15 μm, while the thickness of the H ₁₂ MDI-TPU layer of the second thermoplastic polyurethane layer. A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Comparative Example 3 except that the thickness was 135 μm. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 3.

(Comparative Example 6)
In Comparative Example 3, the thickness of the 1,4-H ₆ XDI-TPU layer of the first thermoplastic polyurethane layer is 10 μm, while the thickness of the H ₁₂ MDI-TPU layer of the second thermoplastic polyurethane layer. A thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Comparative Example 3 except that the size was 140 μm. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 3.

(Comparative Example 7)
In Comparative Example 3, a thermoplastic polyurethane film (thermoplastic polyurethane layer) and a multilayer film were produced in the same manner as in Comparative Example 3 except _{that the polyurethane layer was only a layer of H 12 MDI-TPU having a thickness of 150 μm.} .. Similar to Example 4, the stress relaxation property, tensile property, and optical property of the thermoplastic polyurethane layer were measured, and the engine cleaner resistance of the multilayer film was measured. The results are shown in Table 3.

_{As is clear from the results in Tables 2 and 3, in the multilayer film composed of the 1,4-H 6} XDI-TPU layer having a shore A hardness of 95 or more in Examples 4 to 7 of the present invention, the engine is applied to the surface coat layer. Even when the cleaner was dropped, it did not swell the thermoplastic polyurethane layer, did not change the appearance, and had excellent chemical resistance. _{On the other hand, in the multilayer film made of the reaction product using 1,4-H 6} XDI-TPU having a hardness of less than 95 in Comparative Examples 3 to 6, the engine cleaner swells the thermoplastic polyurethane layer and the appearance becomes whitish. It changed and was inferior in chemical resistance (see FIG. 8). From this, when the thermoplastic polyurethane layer is made into a plurality of layers, in order to improve the chemical resistance, the hardness of the thermoplastic polyurethane layer reaction-generated by using _{1,4-H 6 XDI is the Shore A hardness.} It turned out that it should be 95 or more. Here, the hardness of the thermoplastic polyurethane layer from which chemical resistance can be obtained is higher than that of the single layer because the 1,4-H ₆ XDI-TPU layer is thinner in the case of multiple layers, so that the chemicals are used. There easily _soak, presumably because it reaches the H 12 MDI-TPU layer. In fact _{, even in Comparative Example 7 consisting of only the H 12} MDI-TPU layer, the result was inferior in chemical resistance, which was confirmed.

The value indicating the stress relaxation property and the value indicating the tensile property of the thermoplastic polyurethane layer are both 15 N / 25 mm or less, and have extremely preferable stretchability in order to allow the surface sheet to follow well as a protective sheet. It was speculated that it was. The optical characteristics were also generally good, with a total light transmittance of 92% or more and a haze value of 3.0% or less.

Verification 3. Joining workability addition for a plurality of the thermoplastic polyurethane _layer, in the case where a single layer of 1,4-H 6 XDI-TPU _layer, and 1,4-H 6 XDI-TPU layer and _H 12 MDI-TPU layer In order to confirm the sticking workability of the layered case, the verification was performed as follows.

(Example 8)
A fluorine-modified acrylic polyol (solid content 30%), an isocyanate-based curing agent (solid content 60%), and methyl isobutyl ketone (MIBK) as a diluting solvent were added as a coating liquid for forming a coating film on the surface coat layer at 38:23. A coating solution of fluorine-modified acrylic urethane resin B blended in a mass fraction of: 39 was prepared.

_{Subsequently, the PET film on the 1,4-H 6} XDI-TPU side, which is the first thermoplastic polyurethane layer of the thermoplastic polyurethane layer produced in Example 7, was peeled off, and the 1,4-H ₆ XDI-TPU surface was peeled off. The coating liquid of the fluorine-modified acrylic urethane resin B was applied to the surface so that the thickness after drying was 10 μm to prepare the multilayer film of Example 8.

_{The PET film on the H 12} MDI-TPU side of the produced multilayer film was peeled off, and the stress relaxation property, tensile property, and optical property of the base material layer were measured in the same manner as in Example 1. In addition, the engine cleaner resistance was evaluated in the same manner as in Example 1, and the sticking workability was evaluated as follows. The results are shown in Table 4.

<Attachment workability>
A sample of the produced multilayer film is cut out to A4 size, the PET on the thermoplastic polyurethane layer side is peeled off, an acrylic adhesive is applied, and then a painted steel plate having a curved surface and a step of an automobile door mirror as a protection object is applied to the monitor. I had them pasted on each. As for the difficulty of pasting, the door mirror having a three-dimensional curved surface is higher than the painted steel plate having a step, so the evaluation criteria are as follows.
◯: It was possible to attach the multilayer film to the door mirror of an automobile without causing wrinkles.
Δ: Although wrinkles were generated when the steel plate was attached to the door mirror of an automobile, it could be attached to the painted steel plate having a step without causing wrinkles.
X: Wrinkles also occurred when pasted on a painted steel plate having a step.
As an example, FIG. 9 shows a photograph of the result of the workability of attaching to the automobile door mirror of Example 8, and FIG. 10 shows a photograph of the result of the workability of attaching to the painted steel plate having a step in Example 9.

(Example 9)
In Example 8, the multilayer film (base material layer) of Example 9 was prepared in the same manner as in Example 8 except that the thermoplastic polyurethane layer was replaced with the film prepared in Example 1. With respect to the base material layer of this multilayer film, the stress relaxation property, the tensile property, and the optical property were measured in the same manner as in Example 8, and the engine cleaner resistance and the sticking workability of the multilayer film were evaluated. The results are shown in Table 4.

(Example 10)
In Example 8, the multilayer film (base material layer) of Example 10 was prepared in the same manner as in Example 8 except that the thermoplastic polyurethane layer was replaced with the film prepared in Example 2. With respect to the base material layer of this multilayer film, the stress relaxation property, the tensile property, and the optical property were measured in the same manner as in Example 8, and the engine cleaner resistance and the sticking workability of the multilayer film were evaluated. The results are shown in Table 4.

(Comparative Example 8)
In Example 8, the multilayer film (base material layer) of Comparative Example 8 was prepared in the same manner as in Example 8 except that the thermoplastic polyurethane layer was replaced with the film prepared in Comparative Example 7. With respect to the base material layer of this multilayer film, the stress relaxation property, the tensile property, and the optical property were measured in the same manner as in Example 8, and the engine cleaner resistance and the sticking workability of the multilayer film were evaluated. The results are shown in Table 4.

As is clear from the results in Table 4, all of the multilayer films of Examples 8 to 10 of the present invention were excellent in chemical resistance. However, at the time of attachment, in Example 8, wrinkles did not occur when the product was attached to either the door mirror of the automobile or the painted steel plate having a step (see FIG. 9), whereas in Examples 9 and 10, the wrinkles did not occur. Although no wrinkles were generated on the painted steel sheet having a step (see FIG. 10), wrinkles were generated on the door mirror of the automobile. Therefore, in order to have chemical resistance and obtain excellent sticking workability, it is desired to combine _{the 1,4-H 6} XDI-TPU resin and the H _{12 MDI-TPU resin as in Example 8.} Mareta.

Further, in Example 8, both the values of stress relaxation property and tensile property were good at 20 N / 25 mm or less, but in Examples 9 and 10, the value indicating the stress relaxation property was 25 N / 25 mm. The values indicating the characteristics exceeded 20 N / 25 mm, respectively. Therefore, it is necessary to set these stress values in a suitable range and to make the multilayer film have an appropriate stretchability in order to obtain excellent sticking workability, and as in Example 8, 1,4-H. combining ₆ XDI-TPU resin and the _H 12 MDI-TPU resins were found to be that desired.

On the other hand, in Comparative Example 8, since the TPU layer was _{composed of only H 12} MDI-TPU, the sticking workability was good, but the chemical resistance was inferior.

Regarding the optical characteristics, the total light transmittance was 92% or more and the haze value was 2.0% or less, and all the examples were good.

Although the embodiments and examples of the present invention have been described in detail above, the multilayer film of the present invention is not limited to the above-described embodiments, and may include any technical idea assumed within the scope.

INDUSTRIAL APPLICABILITY The present invention includes a paint protective sheet or a surface protective sheet for preventing scratches and flying stones on the exterior of a vehicle such as an automobile, and a film for protecting the screen by attaching it to a curved surface such as a flexible liquid crystal. , Can be used to protect an adherend having a step or a three-dimensional curved surface.

10,20 Multilayer film 11,21 Thermoplastic polyurethane layer 12 Surface coat layer 13 Adhesive layer 22 First thermoplastic polyurethane layer 23 Second thermoplastic polyurethane layer a Adhesive

Claims (8)

A multilayer film having a thermoplastic polyurethane layer and a surface coating layer.
The thermoplastic polyurethane layer is composed of a single layer or a plurality of layers, and one layer is adjacent to the surface coating layer and is a reaction product using _{hydrogenated xylylene diisocyanate (1,4-H 6 XDI).} The hardness of this layer containing polyurethane and measured according to JIS K7311 is shore A hardness 90 to shore D hardness 65 when it is composed of a single layer, and shore A hardness 95 to shore D hardness 65 when it is composed of multiple layers. A multilayer film characterized by being. The multilayer film according to claim 1, wherein when the thermoplastic polyurethane layer is composed of a plurality of layers, the thickness of the layer adjacent to the surface coating layer is 5 μm or more. When the thermoplastic polyurethane layer is composed of a plurality of layers, the thermoplastic polyurethane layer is made of a layer adjacent to the surface coat layer and a thermoplastic polyurethane which is a reaction product using _{dicyclohexylmethane diisocyanate (H 12 MDI).} The multilayer film according to claim 1 or 2, which is composed of a layer. The multilayer film according to any one of claims 1 to 3, wherein the surface coating layer has a urethane bond. 7. Multilayer film. The multilayer film according to any one of claims 1 to 5, wherein the total light transmittance according to JIS K7361-1 is 90% or more. The multilayer film according to any one of claims 1 to 6, wherein the haze value according to JIS K7136 is 3.0% or less. The multilayer film according to any one of claims 1 to 7, which is used to protect an adherend having a curved surface.

Images