JP2003027016A - Adhesive sheet and marking film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an adhesive sheet which can effectively prevent damages to a sheet, such as a crack of a protective layer, under a low temperature environment and at the same time exhibits excellent protective effects (contamination resistance and weather resistance), and a marking film obtained by using the adhesive sheet. SOLUTION: The adhesive sheet 100 comprises a flexible support 1, an adhesive layer 3 arranged on the back surface of the support 1, and a protective layer 2 arranged on the surface of the support 1 and composed of a hydrophilized coating film which contains a cured resin and an inorganic oxide- based hydrophilizing agent. The support 1 comprises a layer containing a first polyurethane resin composed of a reaction product of a polyester polyol with a multifunctional isocyanate compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a flexible support, an adhesive layer on the back surface of the support, and a protective layer on the front surface of the support. The present invention relates to an adhesive sheet that is adhered to walls and window glasses, and bodies of vehicles, aircraft, ships, etc.). The adhesive sheet of the present invention,
It can also be used outdoors in low temperatures in winter. Therefore, since the adhesive sheet of the present invention can be used outdoors regardless of the season, it is particularly suitable for use as a marking film.

[0002]

2. Description of the Related Art Usually, in an adhesive sheet such as a general film or sheet with an adhesive for outdoor use, a protective layer is usually arranged on the surface thereof in order to improve the stain resistance of the surface. The protective layer is usually a coating film containing an acrylic resin or a fluorocopolymer. In addition, paints that form such coatings are also commercially available.

However, the protective layer formed from the commercially available coating film as described above has a relatively high water contact angle on the surface (usually 70 degrees or more) and exhibits the following properties against contaminants. There was found. Hydrophilic pollutants (sludge, sand dust, dust, dirt from raindrops, etc.): The above protective layer repels water on the surface, so water droplets tend to roll off, but on the other hand, the traces of drying water droplets remaining on the surface Contaminants adhere to and form spots of dirt. Furthermore, since the hydrophilicity of the surface is low, such contaminants once attached are difficult to be removed by a natural cleaning action such as rain. Lipophilic pollutants (waste gas, soot, etc.): Since the surface of the protective layer is relatively lipophilic,
Lipophilic pollutants are easy to attach.

In order to solve the above problems, the present inventors have made a coating film (hydrophilization coating film) containing a hydrophilizing agent (also called a hydrophilicity-imparting agent) an adhesive sheet. It was examined to use it as a protective layer of. Incidentally, such a coating film is disclosed in several documents introduced below.

For example, as disclosed in Japanese Patent Application Laid-Open No. 11-267585, (A) resin component is 30 to 90% by weight, (B) curing agent component is 10 to 70% by weight, and (C) is a nonvolatile component ratio. A clear coat paint comprising 1 to 50% by weight of a hydrophilizing agent is known. As the hydrophilizing agent of the component (C), an organosilicate, an organosilicate condensate, an inorganic oxide sol such as an inorganic oxide sol (aluminum oxide sol, silicon oxide sol, zirconium oxide sol, antimony oxide sol, etc.) is hydrophilized. Agents are disclosed. This clear coat paint is a cured resin (cured resin)
By the combination of the above with an inorganic oxide hydrophilizing agent, it is possible to impart an improved protective effect such as stain resistance and weather resistance to the article coated with the coating film of the paint. Such a paint is also disclosed in JP-A-9-302257. Although these publications disclose that the above-described hydrophilic coating is directly applied to articles such as automobile bodies and traffic signs, such coatings are used as a protective layer of an adhesive sheet. That is not taught.

US Pat. No. 5,820,978 discloses an article such as a reflection sheet having a water-spreading layer as a surface protective layer, the layer spreading thin water. , An article containing a silicon oxide compound having a metal oxide film on its surface is disclosed. The metal of the metal oxide film is preferably selected from the group consisting of aluminum, gallium, germanium, tin, indium, arsenic, antimony and vanadium. Such a layer that spreads water thinly can also be used as a hydrophilic protective layer.

On the other hand, some conventional adhesive sheets are provided with a protective layer, which does not contain the above-mentioned inorganic oxide-based hydrophilizing agent but contains a cured resin, on the surface of the support. For example, as disclosed in JP-A-1-225551, there is a protective layer formed of a cured coating film of a coating material containing an electron beam curable oligomer. Further, Japanese Utility Model Application Laid-Open No. 5-76732 discloses a decorative film (decorative sheet) having a protective layer cured by electron beam similar to the above. Further, in JP-A-2000-191993, in an adhesive sheet having a protective layer fixed on the surface of a support and an adhesive layer arranged on the back surface of the support, the protective layer is:
An adhesive sheet containing a cured resin and transparent beads dispersed in the cured resin is disclosed.

As described in these publications, the support used in the conventional adhesive sheet or decorative sheet is usually polyvinyl chloride, polyester, polyurethane, acrylic polymer, fluorine polymer, polyolefin. Was a plastic film. However, these publications did not discuss the material and physical properties of the support in detail.

[0009]

By the way, a hydrophilic coating film containing an inorganic oxide-based hydrophilizing agent and a cured resin has excellent protective effects such as stain resistance and weather resistance,
When used in combination with an ordinary adhesive sheet, it had the following problems to be solved.

An adhesive sheet adhered to the surface of an adherend used outdoors such as a wall surface of a building or a signboard is adhered, that is, constructed in an outdoor temperature environment. However, when the sheet is bent during construction in a low-temperature environment outdoors in winter (for example, winter in Japan), or when impact is received due to collision of flying stones on the sheet surface during construction or after construction, Occasionally, sheet damage such as cracking of the protective layer occurred. Such cracks may be deep throughout the thickness of the adhesive sheet, and the adherend may be exposed through the cracks in the adhesive sheet that has been applied. When the present inventors analyzed such a phenomenon, a protective layer containing both an inorganic oxide-based hydrophilizing agent and a cured resin has a low impact resistance particularly at low temperatures, and such a protective layer was formed. It has been found that the provided adhesive sheet is likely to cause sheet damage such as cracks as described above.

Therefore, an object of the present invention is to effectively prevent sheet damage such as cracking of a protective layer in a low temperature environment, and at the same time, have an excellent protective effect (contamination resistance and weather resistance), Another object of the present invention is to provide a marking film using this adhesive sheet.

[0012]

[Means for Solving the Problems] That is, according to the present invention, a flexible support, an adhesive layer disposed on the back surface of the support, and a cured resin disposed on the surface of the support. And a protective layer comprising a hydrophilic coating film containing an inorganic oxide hydrophilizing agent, wherein the support comprises a reaction product of a polyester polyol and a polyfunctional isocyanate compound. There is provided an adhesive sheet comprising a layer containing a polyurethane resin.

In the adhesive sheet of the present invention, the low temperature elongation of the support, defined as the elongation at break measured at a pulling speed of 300 mm / min at 5 ° C., is the low temperature elongation of the protective layer measured in the same manner. The elongation is preferably larger than the elongation, and the thickness of the support is preferably larger than the thickness of the protective layer, and the support has a thickness of 300 at 5 ° C.
Low temperature elongation measured at a pulling speed of mm / min of 50 to 10
It is preferably in the range of 0%. Furthermore, the low-temperature elongation of the support measured at a pulling speed of 300 mm / min at 5 ° C. is 50% or more and 300 mm at 25 ° C.
It is desirable that the room temperature elongation, which is defined as the elongation at break measured at a tensile speed of 1 / min, is 200% or less.

The support in the adhesive sheet of the present invention includes (i) a lower layer containing the first polyurethane resin, and (ii) disposed between the lower layer and the protective layer,
A second layer which is in close contact with the protective layer and which comprises a reaction product of a polycarbonate polyol and a polyfunctional isocyanate compound.
Preferably, the upper layer comprises a polyurethane resin, and the thickness of the lower layer is larger than the thickness of the upper layer.

Further, according to the present invention, in the marking film comprising the adhesive sheet having the above-mentioned constitution, the protective layer is substantially transparent, and the lower layer of the support is transparent substantially containing no pigment. A marking film is provided which is a layer or a white layer containing a white pigment, wherein the upper layer of the support contains a coloring pigment and is a colored layer colored other than white.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the adhesive sheet of the present invention, the flexible support contains a layer (first polyurethane resin) containing a polyurethane (first polyurethane resin) which is a reaction product of a polyester polyol and a polyfunctional isocyanate compound. A polyurethane resin layer). As a result, it is possible to effectively prevent sheet damage such as cracking of the protective layer in a low temperature environment. It also has a protective layer consisting of a hydrophilic coating, so it has excellent protective effects (stain resistance and weather resistance).
Can be demonstrated.

In the present invention, the protective layer composed of the hydrophilic coating film containing the cured resin and the inorganic oxide-based hydrophilic agent can exhibit the same excellent protective effect as the conventional one. On the other hand, since the support contains polyester polyol-based polyurethane (first polyurethane resin), it has a large elongation at low temperature (about 5 ° C.). Therefore, in a low-temperature environment, the support can effectively absorb the impact directly received by the protective layer as a cushion, and since the flexibility of the entire sheet is high, the adhesive sheet may be cracked in the thickness direction. It can be effectively prevented.

The low temperature elongation of the support, ie the elongation at break measured at 5 ° C., is preferably in the range 50-100%. If the low-temperature elongation is less than 50%, it may not be possible to effectively prevent the occurrence of cracks in a low-temperature environment. On the other hand, if it exceeds 100%, when the work is carried out at room temperature (about 25 ° C) or higher. In addition, the sheet tends to be excessively stretched and plastically deformed or broken. From such a viewpoint, the low temperature elongation is particularly preferably in the range of 60 to 95%. In the present specification, the low temperature elongation is 5 for a test piece composed of a coating film having a thickness of about 35 μm.
It is a value measured by conducting a tensile test at a tensile rate of 300 mm / min at 0 ° C.

From the same viewpoint as described above, the breaking elongation (normal temperature elongation) of the support measured at a pulling speed of 300 mm / min at 25 ° C. is preferably 200% or less. When the room temperature elongation exceeds 200%, the room temperature (about 25 ℃)
Alternatively, when the sheet is applied at a temperature higher than that, the sheet tends to be excessively stretched and plastically deformed or broken. From this point of view, it is particularly preferable that the room temperature elongation is 180% or less. The room temperature elongation is a value measured by performing a tensile test on a test piece composed of a coating film having a thickness of about 35 μm at 25 ° C. at a tensile speed of 300 mm / min.

In order to effectively enhance the protective effect, the protective layer is preferably relatively hard. Therefore, the low temperature elongation of the protective layer is smaller than the low temperature elongation of the support, which is likewise measured. In such a case, it is advantageous that the thickness of the support is larger than the thickness of the protective layer in terms of enhancing the impact absorbing action as described above.

(Adhesive Sheet) An adhesive sheet (100) according to a preferred embodiment of the present invention has a structure as shown in FIG. As shown in the figure, the adhesive sheet (100) has a flexible support (1), an adhesive layer (3) disposed on the back surface of the support (1), and an adhesive layer (3) disposed on the surface of the support (1). And a protective layer (2) comprising a hydrophilized coating film containing a cured resin and an inorganic oxide hydrophilizing agent. The support (1) may be composed of a single layer containing the first polyurethane resin, but is preferably composed of a laminate of two or more layers.

In the illustrated example, the support (1) is a laminate (laminated film) including a lower layer (11) and an upper layer (12) that are in close contact with each other. That is, the front surface (111) of the lower layer (11) and the back surface (122) of the upper layer (12) are in close contact with each other, and the protective layer (2) is in close contact with the surface (121) of the upper layer (12). Adhesive layer (3) on back surface (112)
Are in close contact.

The support (1) includes a lower layer (11) arranged on the side of the adhesive layer (3) and an upper layer (12) arranged in close contact with the lower layer (11) and arranged on the side of the protective layer (2). It is preferable that the lower layer (11) contains the first polyurethane resin and the thickness of the lower layer (11) is larger than that of the upper layer (12). In this way, by arranging the cushion layer having a relatively large thickness in the lowermost layer closest to the adhesive layer (3), the shock absorbing effect at low temperature can be effectively exhibited, and the entire sheet can be used even in a low temperature environment. The flexibility of can be effectively increased.

In addition, the upper layer (1) that is in close contact with the protective layer (2)
It is preferable that 2) comprises a polyurethane resin which is relatively hard as compared with the lower layer (11), that is, a second polyurethane resin which is a reaction product of a polycarbonate polyol and a polyfunctional isocyanate compound. As a result, even when the cured resin of the protective layer (2) is relatively hard and the low temperature elongation is largely different from the low temperature elongation of the support lower layer (11), the upper layer (12) mediates and the support ( 1) Effectively increase the adhesion between the whole and the protective layer (2). This allows
When the sheet is bent in a low temperature environment or the sheet is impacted, it is possible to effectively prevent the sheet from being damaged due to the protective layer (2) peeling from the support (1).

In the case as described above, the low temperature elongation of the support upper layer (12) was measured by the same method as the support lower layer (1).
It is preferable that the breaking elongation (low temperature elongation) of 1) is smaller. The lower layer (11) measured by the above method
Low temperature elongation is usually 40 to 120%, preferably 50 to 1
The low temperature elongation of the upper layer (12) is usually 5 to 40%, preferably 7 to 30%. Also,
The room temperature elongation of the lower layer (11) measured by the above method is usually 120 to 250%, preferably 130 to 230%, and the room temperature elongation of the upper layer (12) is usually 30 to 150%.
%, Preferably 40 to 140%.

The support (1) is the upper layer (12) as described above.
And an underlayer (11), the adhesive sheet of the present invention is suitable for use as a marking film. In this case, the lower layer (11) of the support is a transparent layer substantially free of pigment or a white layer containing a white pigment, and the upper layer (12) contains a coloring pigment and is colored in a color other than white. The colored layer is preferably a colored layer. As mentioned above,
The lower layer (11) contains a polyurethane formed from a polyester polyol, but such a polyester-based polyurethane has relatively low weather resistance. Therefore, when the layer containing the polyester-based polyurethane is colored and the layer is observable and used, fading (discoloration) of the color over time easily occurs. On the other hand, the polycarbonate polyol-based polyurethane has excellent weather resistance.
Therefore, it is preferable to make the upper layer (12) observable as a colored layer. In this case, the upper layer (1
Since 2) is usually thinner than the lower layer (11), the color of the lower layer (11) is easily visible through the upper layer (12). Therefore, if the lower layer (11) is transparent or white, the color definition of the upper layer (12) can be effectively increased.

For example, when the marking film according to the present invention is used by being adhered to an opaque adherend, in order to conceal the color of the adherend and effectively enhance the color clarity of the colored layer, the lower layer ( 11) is preferably white. Also, by adhering to a light-transmissive adherend, with illumination light from the back of the adherend,
When the colored layer is observed from the surface of the adherend, the lower layer (11) is preferably transparent or white translucent (diffuse translucent).

(Support) The support (1) is, as described above,
A single layer film consisting only of a layer containing the first polyurethane resin (first polyurethane resin layer), or the first layer
It is a laminated film including a polyurethane resin layer and another layer. Usually, 1 is used as the raw material for the first polyurethane resin.
Or two or more polyester polyols are included. The polyester polyol means a polymer or oligomer having a polyester bond in the molecule and at least two hydroxyl groups at both ends of the molecule.

The OH equivalent of the polyester polyol is
Although not particularly limited, it is usually 200 to 30,000, preferably 500 to 10,000. If the OH equivalent is too small, the impact absorption effect at low temperatures may be reduced, while if it is too large, the sheet will be excessively stretched and plastically deformed when applied at room temperature (about 25 ° C) or higher. It may be broken or broken. In the present specification, the "OH (hydroxyl group) equivalent" of the polyol is O
It means the molecular weight of the polyol per one H (hydroxyl group).

As the polyfunctional isocyanate compound, a compound having two or more isocyanate functional groups in the molecule and a usual one can be used as long as it has a predetermined NCO equivalent. The NCO equivalent of the isocyanate compound contained in the raw material of the first polyurethane resin is usually 50 to 2,000.
The range is 0, preferably 70 to 1,000. Although it depends on the OH equivalent of the polyol, if the NCO equivalent is too small, the impact absorption effect at low temperature may be deteriorated. , The sheet may be excessively stretched and may be plastically deformed or fractured. In addition, "NCO (isocyanate group) equivalent" of the polyfunctional isocyanate compound
Means the molecular weight of the isocyanate compound per NCO (isocyanate group). Further, the number of functional groups in the molecule of the polyfunctional isocyanate compound is not particularly limited as long as the low temperature elongation of the entire support and the first polyurethane resin layer is sufficiently large and the shock absorbing property is exhibited, but it is 2 to 2.8.
It is good to be an individual.

As the polyester polyol, for example, 1 selected from the group consisting of adipic acid, hexamethylenedicarboxylic acid, isophthalic acid and orthophthalic acid.
Formed from one or more dicarboxylic acids and one or more diols selected from the group consisting of 1,6-hexanediol, ethylene glycol, propylene glycol, tetramethylene glycol and caprolactone diol. It is possible to use those having the above-mentioned polyester unit in the main chain and having hydroxyl groups at both ends of the main chain. Further, a polyol obtained by ring-opening polymerization of caprolactone can also be used. In addition to the above diol compounds, triols such as 1,1,1-trimethylolpropane and glycerin can be incorporated into the main chain so that the side chains have hydroxyl groups. In addition, in order to enhance the impact absorbability, a polyester polyol using an aliphatic dicarboxylic acid as a raw material is preferable.

The isocyanate compound is, for example, one or more diisocyanates selected from the group consisting of isophorone diisocyanate, MDI (diphenylmethane diisocyanate), hydrogenated MDI and 1,6-hexanediol diisocyanate. Further, those synthesized from starting materials containing such a diisocyanate can also be used. For example, (A) the above-mentioned triol (1,1,1-trimethylolpropane, etc.),
A compound obtained by subjecting the diisocyanate to a urethane reaction, or (B) a compound having a biuret structure or an isocyanurate structure obtained by reacting the diisocyanates with each other can be used. Further, in order to adjust the NCO equivalent, a polyfunctional isocyanate compound obtained by reacting the above compound with a diol such as polycaprolactone diol can also be used.

The first polyurethane resin layer may contain polyurethane formed from a polyol other than the polyester polyol as long as the impact absorbing effect at low temperature is not impaired. Examples of such polyols include polyether polyols and acrylic polyols.

When the support (1) is composed of a laminated film, the other layer combined with the first polyurethane resin layer is usually a layer having a thickness smaller than that of the first polyurethane resin layer. Also, as mentioned above, the further layer is preferably arranged between the first polyurethane resin layer and the protective layer (2). Although the structure of such another layer is not particularly limited, preferably, as described above, a layer containing a second polyurethane resin composed of a reaction product of a polycarbonate polyol and a polyfunctional isocyanate compound (second polyurethane). Resin layer).

The raw material of the second polyurethane resin contains one kind or two or more kinds of polycarbonate polyols. Polycarbonate polyol has the formula "-OR-
An alkylene polycarbonate skeleton or an aralkylene polycarbonate skeleton represented by "O- (C = O)-" is included in the molecule and means a polymer or oligomer having at least two hydroxyl groups at both ends of the molecule. The OH equivalent of the polycarbonate polyol is not particularly limited, but is usually 200 to 30,000, preferably 500 to 1
It is 10,000.

R in the above formula is an aromatic or aliphatic hydrocarbon group. R is preferably an aliphatic hydrocarbon group, and particularly preferably a linear aliphatic hydrocarbon group.
The aliphatic hydrocarbon group can effectively enhance the adhesive force of the second polyurethane resin layer to the protective layer (2) and the first polyurethane resin layer. In addition, the weather resistance of the second polyurethane resin layer can be enhanced particularly effectively. In order to improve the weather resistance of the second polyurethane resin layer,
Suitably, the isocyanate compound reacted with the polycarbonate polyol is an aliphatic polyfunctional isocyanate compound.

As the polyfunctional isocyanate compound for forming the second polyurethane resin, the same types as those described above can be used. The NCO equivalent of the isocyanate compound is usually 100 to 2,000, preferably 200 to 1,000. The number of functional groups in the molecule of the polyfunctional isocyanate compound is not particularly limited as long as it does not prevent the shock absorbing property of the support from being exhibited,
It is good that the number is 2 to 2.8.

The second polyurethane resin layer may contain a polyurethane formed from a polyol other than a polycarbonate polyol, as long as the effects of the present invention are not impaired. Examples of such polyols include polyether polyols and acrylic polyols.

The support is formed, for example, as follows. First, a coating material containing a polyurethane resin or a raw material for forming the polyurethane resin is prepared. The polyurethane resin to be contained in the paint may be a polyurethane resin in which the reaction has been completed in advance, or a raw material containing a polyol and a polyfunctional isocyanate compound may be contained in the paint and the reaction may proceed in the coating film of the paint. . The concentration of non-volatile components (polyurethane, polyol and polyfunctional isocyanate compound, etc.) contained in the entire paint is usually 1
It is 5 to 85% by mass, preferably 30 to 80% by mass.

The coating material thus prepared is applied to the surface of the process substrate and dried by heating to form a support. To apply the paint, for example, a printing method such as silk printing or a coating method such as a knife coater or a bar coater is adopted. The coating weight at the time of coating is usually 10 to 80 g / m ² , and preferably 12 to 70 g / m ² . The drying temperature is usually 60
The temperature is ˜180 ° C. Further, in order to accelerate the reaction between the isocyanate compound and the polyol, it is usually 30 to 6
The heat treatment may be performed at a temperature of 0 ° C. for 1 to 21 days.

When the support (1) is a laminated film, the support is formed by laminating the coating film of the first polyurethane resin paint and the coating film of the second polyurethane resin paint in the same manner as above. For example, a first polyurethane resin layer is formed on a process base material from a coating film of the first polyurethane resin coating material, and then a second polyurethane resin coating material is applied on the first polyurethane resin layer and dried.

The total thickness of the support (1) thus obtained is usually 20 to 200 μm, preferably 30 to 15
It is 0 μm. When the support (1) is a laminated film, the thickness of the first polyurethane resin layer is usually 20 to 1
It is 50 μm, preferably 30 to 130 μm, and the thickness of the second polyurethane resin layer is usually 1 to 100 μm, preferably 2 to 70 μm.

A colorant such as a pigment may be contained in the layer constituting the support (1). The content of the pigment is usually 1 to 80% by mass based on the total mass of the layer. In addition to the colorant, additives such as an ultraviolet absorber, a heat stabilizer and a plasticizer may be added as long as the effects of the present invention are not impaired.

(Protective Layer) As described above, the protective layer (2) is
It is composed of a hydrophilized coating film containing essential components consisting of a cured resin and an inorganic oxide-based hydrophilizing agent. The "hydrophilic coating film" is a coating film having a hydrophilic surface, and the water contact angle of the surface is less than 70 degrees, and preferably controlled to a predetermined range of 65 degrees or less. When the water contact angle on the surface of the protective layer is 65 degrees or less, the stain resistance can be effectively enhanced and maintained for a relatively long period of time.

In order to control the water contact angle on the surface of the protective layer within a predetermined range of 65 degrees or less, a combination of a cured resin and an inorganic oxide hydrophilizing agent is effective. As described above, the inorganic oxide-based hydrophilizing agent acts to enhance the protective effect such as stain resistance, but when combined with the cured resin, the protective layer surface becomes unnecessary hydrophilic (for example, water contact). It is possible to prevent the angle from becoming less than 35 degrees.

From the viewpoint of stain resistance, the lower limit of the water contact angle on the surface of the protective layer is not particularly limited. However, as described below, another adhesive sheet may be laminated and adhered (lapped) on the surface of the protective layer of the adhesive sheet of the present invention. In such a case, in order to effectively prevent the deterioration of the water resistant adhesive strength of the adhesive sheet laminated, it is preferable that the water contact angle of the surface of the protective layer is 35 degrees or more.

On the surface (that is, the protective layer surface) of the adhesive sheet (first adhesive sheet) adhered to the surface of the adherend used outdoors such as the wall surface of a building or a signboard, another adhesive sheet (first 2 adhesive sheets) are often overlaid. For example, the first adhesive sheet is first adhered to the surface of the signboard as a base, and then the second adhesive sheet cut into the shape of a design, letters, etc. is adhered to the surface to form an adhesive structure. In such a case, the second adhesive sheet in contact with the hydrophilized coating film can be adhered with a sufficient adhesive force in a normal state, but when the adhesive structure is exposed to water such as rain for a long time,
The adhesive force (peeling resistance) between the surface of the protective layer (hydrophilic coating film) of the adhesive sheet and the second adhesive sheet, that is, the water resistant adhesive force may decrease. Therefore, from such a viewpoint, the water contact angle on the surface of the protective layer is preferably 35 degrees or more.

In order to enhance the stain resistance and the effect of preventing the decrease in the water resistant adhesive strength of the second adhesive sheet in a well-balanced manner,
The water contact angle on the surface of the protective layer is preferably 40 to 64 degrees. Further, it is preferable that the cured resin of the protective layer contains substantially no fluorine-containing polymer but contains a non-fluorine-containing polymer (a polymer not containing a fluorine atom in the molecule). This is because it is particularly advantageous to effectively prevent the reduction of the water resistant adhesive strength of the second adhesive sheet.

The water contact angle means an initial value just after using the adhesive sheet. In addition to the initial value being in the above range, the sunshine weatherometer (WO
The water contact angle after 1,000 hours of test in M) is also preferably in the above range. The water contact angle is the contact angle between the surface of the protective layer and water measured using a contact angle meter after dropping a water droplet on the surface of the protective layer. The water used is usually purified water obtained by distilling ion-exchanged water.

On the other hand, the thickness of the protective layer (2) is usually 0.
It is 1 to 15 μm, preferably 1 to 10 μm. If the thickness of the protective layer (2) is too thin, the strength of the protective layer (2) may be reduced and the protective effect may be reduced. Further, since the protective layer (2) contains a cured resin, on the contrary, if the protective layer (2) is too thick, the flexibility and elongation of the entire adhesive sheet may decrease.

The inorganic oxide hydrophilizing agent is, for example,
(I) Silicon oxide-containing compounds such as organosilicate compounds (organosilicate, organosilicate condensate, etc.), (ii) At least inorganic oxide sols such as silicon oxide sol, aluminum oxide sol, zirconium oxide sol, antimony oxide sol It is a compound that contains any one of them and can control the water contact angle of the protective layer within a predetermined range.
Suitable as such a compound is disclosed in JP-A-9-
Those disclosed in Japanese Patent No. 302257 and Japanese Patent Laid-Open No. 11-267585 are useful.

Suitable as the hydrophilizing agent is an organosilicate compound. The organosilicate compound is used, for example, in the form of a silane coupling agent (silicon oxide surface treating agent) supported on the surface of an inorganic oxide sol such as silica sol or a silica sol in which the particle surface is coated with an organic polymer. To be done. The average particle size of the sol is usually 1
It is not more than 00 nm.

The hydrophilizing agent is usually 1 to 50 parts by mass, preferably 3 to 40 parts by mass, relative to 100 parts by mass of the cured resin.
It is particularly preferably contained in the range of 5 to 30 parts by mass. If the amount of the hydrophilizing agent is too small, the water contact angle on the surface of the protective layer exceeds a predetermined range, and the protective effects such as stain resistance may decrease. On the contrary, if the amount is too large, the protective layer surface The water contact angle may fall below a predetermined range, and the water resistant adhesive strength of the second adhesive sheet may be reduced.

(Cured Resin for Protective Layer) As described above, the protective layer (2) contains a cured resin. The cured resin is a resin containing a cured polymer. When a curing agent is added to cure the polymer, curable resin means a resin composition formed from a mixture of the polymer and the curing agent.

A cured resin containing a non-fluorine-based polymer is preferable. The non-fluorine-based polymer has a function of enhancing the water resistant adhesive strength of the second adhesive sheet as described above. As the non-fluorine-based polymer, acryl-based, polyolefin-based, polyester-based, polyurethane-based, and silicone-based (including modified silicone such as silicone polyurea) polymers can be used. Such polymers have hydroxyl groups,
A curable polymer having a functional group capable of reacting with a curing agent such as a carboxyl group, an epoxy group, an amino group, or a photocurable functional group.

When the curable resin is formed from a curable polymer and a curing agent, the curing agent is not particularly limited, but an isocyanate compound or an epoxy compound is suitable.
The content ratio of the curable polymer and the curing agent is usually 40 to 95 parts by mass of the curable polymer, and the curing agent 5 corresponding thereto.
To 60 parts by mass, preferably 30 to 90 parts by mass of the curable polymer, and correspondingly 10 to 70 parts by mass of the curing agent.

In addition to the above-mentioned components, the protective layer (2) has the purpose of improving weather resistance, stability, and other properties.
It is also possible to add an ultraviolet absorber, a stabilizer, or other additives. The method for forming the protective layer (2) is not particularly limited, but a coating liquid formed by dissolving or dispersing all components such as a hydrophilizing agent, a polymer and a curing agent in a solvent is applied on the surface of the support (1). It is better to dry and form a coating film. The drying conditions should be relatively mild, and a temperature of 50 to 90 ° C. and a drying time of 3 to 60 minutes are preferable.

(Adhesive Layer) As the adhesive layer (3) arranged on the back surface of the support (1), those used in ordinary adhesive sheets can be used. Usually, it is a layer containing an adhesive such as a pressure-sensitive adhesive (adhesive), a heat-sensitive adhesive (including a hot-melt adhesive), and a solvent activated adhesive. As the adhesive, for example, when considering processability, workability, weather resistance, and price,
It is preferable to use an acrylic adhesive. An ultraviolet absorber and a heat stabilizer for improving weather resistance can be added to the pressure-sensitive adhesive. Further, in order to improve the adhesive force, a crosslinking agent (curing agent), a tackifier, a plasticizer or the like can be added. Considering that it is adhered to an adherend requiring conformability when applied to an adherend having a surface distortion, it has a peel strength of 5 to 50 N / 25 mm (180 degree peel, 300 mm / min). Adhesives are preferred.

As the adhesive, in addition to acrylic adhesives, polyolefin-based, polyester-based, polyurethane-based, silicone-based (including modified silicone such as silicone polyurea), and epoxy-based adhesives can also be used. The adhesive layer is
It can be formed from a coating film of a coating liquid containing an adhesive. The thickness of the adhesive layer is not particularly limited, but is usually 5 to 500 μm.
m, usually 10 to 300 μm.

[0060]

[Example] (Example) First, a process substrate (having a thickness of 50 μm
A support was formed on the above PET film) in the following manner. As a coating material for forming the lower layer of the support, 100 parts by mass of a first polyurethane resin, which is a reaction product of a polyester polyol formed using an aliphatic dicarboxylic acid as a raw material, and an aliphatic polyfunctional isocyanate compound, and a white pigment A coating material containing 100 parts by mass (nonvolatile component concentration 7
5% by mass) was prepared. This coating material is applied onto a process substrate with a knife coater, and the temperature is 65 ° C. for 1 minute and 85 ° C. for 1 minute.
It was heated and dried to form a support lower layer having a thickness of 35 μm.

Next, as a coating material for forming the upper layer of the support, 100 parts by mass of a second polyurethane resin, which is a reaction product of a polycarbonate polyol and an aliphatic polyfunctional isocyanate compound, 50 parts by mass of a blue pigment, and a yellow color. A coating material (nonvolatile content concentration: 52% by mass) containing 50 parts by mass of pigment and 25 parts by mass of white pigment was prepared. This paint
Apply with a knife coater on the surface of the lower layer on the process substrate, and
The substrate was heated and dried at 5 ° C. for 1 minute, 85 ° C. for 1 minute, and 160 ° C. for 1 minute to form a support upper layer having a thickness of 10 μm. Thereby, a support with a process base material was obtained. In this support, the ratio of the thickness of the lower layer to the thickness of the upper layer was 7: 2.

The low temperature elongation of the thus obtained support was 80%. The low temperature elongation was measured using a laminated film prepared by using the same paint as above (the thickness of each layer was adjusted while maintaining the thickness ratio so that the total thickness was about 35 μm). , 10 cm in length and 25 mm in width in a constant temperature environment of 5 ° C. for 30 along the length direction.
It is a value measured by performing a tensile test at a tensile speed of 0 mm / min. The room-temperature elongation of the support was 170%. The measurement of the room temperature elongation is a value measured in a constant temperature environment of 25 ° C. in the same manner as the low temperature elongation.

Of the support (upper layer) obtained as described above
Apply a coating for the protective layer on the surface with a knife coater, and
It was heated and dried at 00 ° C. for 3 minutes, and a protective layer was adhered to the surface of the support to obtain a support with a protective layer. The thickness of the protective layer was 3 μm.

The coating material for the protective layer is a hydrophilic coating material (trademark: Bellclean Clear No. 5000) manufactured by NOF CORPORATION.
Hardener coating (containing polyfunctional isocyanate compound)
Was prepared by mixing. The mixing ratio of the hydrophilic coating (nonvolatile content 46% by mass) and the curing agent coating (nonvolatile content 70% by mass) was 65:35 (mass ratio).

The hydrophilizing paint used here contained an organosilicate compound-based hydrophilizing agent (silane coupling agent supported on the surface of silica sol) and an acrylic polyol-based resin.

Finally, the process base material was removed from the support with the protective layer, and a separately prepared adhesive layer with a liner was pressure-bonded to the back surface (lower layer) of the support to complete the adhesive sheet of this example. The adhesive layer contains an acrylic pressure-sensitive adhesive,
It was a layer with a thickness of 30 μm.

The low temperature elongations of the support lower layer, the support upper layer and the protective layer used in this example were 91% and
10% and 7%. In addition, low temperature elongation is 35 μm in thickness and 1 in length composed of the coating film used for each layer.
It is a value measured by the above-mentioned method with respect to a test piece of 0 cm and a width of 25 mm. The room temperature elongations of the lower support layer, upper support layer and protective layer were 180%, 125% and 12%, respectively. The room-temperature elongation is 35 μm in thickness, 10 cm in length, consisting of the coating film used for each layer.
It is a value measured by the above-mentioned method with respect to a test piece having a width of 25 mm. The adhesive sheet of this example was evaluated as follows. The results are shown in Table 1.

(Comparative Example) As a support, a support (thickness: 45 μm) formed of a coating film of the above-mentioned coating material for a support upper layer was used, and the above-mentioned protective layer was formed on the support, The example adhesive sheet was completed. The results of evaluation of the adhesive sheet of this example in the same manner as in Example 1 are shown in Table 1.

(Evaluation method) Low temperature impact resistance: length 250 mm × width 25 mm × thickness 3 m
The adhesive sheet of each example was adhered to the surface of the aluminum substrate of m in a thermostatic chamber at 25 ° C. to prepare a test piece. After leaving this test piece in a 5 ° C. environment for 24 hours, the test was conducted in a 5 ° C. environment as follows. From a height of 50 inches (about 1.27 m) measured from the surface of the adhesive sheet on the test piece, the pointed tip of a 1-lb (about 454 g) weight was dropped downward to collide with the test piece. . The surface of the adhesive sheet after the collision was visually observed. The case where the adhesive sheet was deformed while being in close contact with the substrate and no crack was visually recognized from the surface of the protective layer was defined as “good”, and the case where cracks were observed in the protective layer and / or the support was defined as “poor”. In the adhesive sheet of the comparative example, cracks were formed in the depth direction of the sheet, and the substrate surface was observed between the cracks.

Weather resistance: Using a metal halide lamp type accelerated weather resistance tester, a test piece prepared in the same manner as in the case of low temperature impact resistance was visually inspected for the appearance of the adhesive sheet after being irradiated with 70 mW of ultraviolet rays for 300 hours. I observed. Using the adhesive sheet saved as a target sample without testing,
In comparison, if any of delamination, cracking, and color change was observed, it was regarded as “poor”, and none of them was observed, and there was almost no change in appearance compared to the target sample. It was defined as “good”.

Contamination resistance: A test piece prepared in the same manner as in the case of low temperature impact resistance was left outdoors, and the contamination state after 4 months was visually observed. As an object sample, an adhesive sheet stored indoors was used, and in comparison with that, when almost no stain could be observed, the result was “good”, and when stain was observed, it was “bad”.

Water contact angle: A water drop is dropped on the surface of the protective layer of the adhesive sheet, and a contact angle meter manufactured by Kyowa Interface Science Co., Ltd. “Part number: CA
-Z type "was used to measure the contact angle between the surface of the protective layer and water according to the procedure described in the manual. The water used was purified water obtained by distilling ion-exchanged water. Further, the initial value is a value measured for an unused adhesive sheet, and the value after WOM 1000h is a sunshine weatherometer weathering accelerated test according to JIS standard, 1,0
It is the value measured after 00 hours.

[0073]

[Table 1]

[0074]

As described above, according to the adhesive sheet of the present invention, it is possible to effectively prevent sheet damage such as cracking of the protective layer in a low temperature environment, and yet to provide an excellent protective effect (contamination resistance and stain resistance). It has a remarkable effect of having weather resistance.
Further, by using such an adhesive sheet of the present invention, it is possible to provide a marking film that can be suitably used outdoors regardless of the season.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an embodiment of an adhesive sheet according to the present invention.

[Explanation of symbols]

1 ... Support, 2 ... Protective layer, 3 ... Adhesive layer, 11 ... Support lower layer, 12 ... Support upper layer, 100 ... Adhesive sheet, 11
1 ... Front surface of support lower layer, 112 ... Back surface of support lower layer, 1
21 ... Front surface of support upper layer, 122 ... Back surface of support upper layer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideto Endo             5500 Wakagi, Higashine, Yamagata Prefecture Yamagata pickpocket             ー M Co., Ltd. F-term (reference) 4F100 AA17C AK01C AK51A AR00A                       AR00B AR00D BA03 BA04                       BA07 BA10B BA10C BA25                       CA13A CA13D CA30C EH46                       GB90 JB12C JK08A JK17A                       JL06 JL09 JL10A JL10D                       JL11B JN01A JN01C YY00A                 4J004 AA07 AA10 AA11 AA13 AA14                       AA15 AB01 AB03 CA06 CC03                       CD02 CD05 CD06 EA06 FA01                       FA04                 4J040 DA001 DF001 EC001 ED001                       EF001 EK001 JA09 JB01                       JB09 KA16 KA26 KA27 KA29                       KA31 LA07 MA03 MA05 MB09                       NA12 NA15 PA23 PA30 PA33

Claims (6)

[Claims] 1. A flexible support, an adhesive layer disposed on the back surface of the support, a cured resin disposed on the surface of the support, and an inorganic oxide hydrophilizing agent. In an adhesive sheet having a protective layer made of a hydrophilic coating, the support comprises a layer containing a first polyurethane resin made of a reaction product of a polyester polyol and a polyfunctional isocyanate compound. Characteristic adhesive sheet. 2. The support is 300 mm at 5 ° C.
The low temperature elongation, defined as the elongation at break measured at a pulling rate of / min, is greater than the low temperature elongation of the protective layer, which is likewise measured, and the thickness of the support is greater than the thickness of the protective layer. The adhesive sheet according to claim 1, which is large. 3. The support is 300 mm at 5 ° C.
The adhesive sheet according to claim 1, wherein the low temperature elongation, defined as the elongation at break measured at a pulling rate of 1 / min, is in the range of 50 to 100%. 4. The support is 300 mm at 5 ° C.
Low temperature elongation, defined as elongation at break measured at a pulling rate of 1 / min of 50% or more, 300 mm /
The adhesive sheet according to claim 1, wherein the room-temperature elongation, which is defined as the elongation at break measured at a tensile rate of minutes, is 200% or less. 5. The support is disposed between (i) a lower layer containing the first polyurethane resin and (ii) the lower layer and the protective layer, and adheres to the protective layer to form a polycarbonate polyol. The adhesive sheet according to claim 1, further comprising: an upper layer containing a second polyurethane resin formed of a reaction product of a polyfunctional isocyanate compound, the lower layer having a thickness larger than that of the upper layer. 6. A marking film comprising the adhesive sheet according to claim 5, wherein the protective layer is substantially transparent, and the lower layer of the support is a transparent layer substantially free of pigment or a white layer. A marking film, which is a white layer containing a pigment, wherein the upper layer of the support contains a coloring pigment and is a colored layer colored other than white.