JP2018150392A - Vehicle window film - Google Patents

Abstract

A vehicle window film capable of effectively preventing the occurrence of white turbidity after sticking is provided. The vehicle window film of the present invention includes a base material and an adhesive layer, and the storage elastic modulus of the adhesive layer at 25 ° C. is 1.0 × 10 5 Pa or more. . The pressure-sensitive adhesive layer is preferably composed of a material containing an acrylic pressure-sensitive adhesive. It is preferable that the glass transition point of the adhesive which comprises the said adhesive layer is -25 degreeC or more. [Selection figure] None

Description

  The present invention relates to a vehicle window film.

  In recent years, for example, window films that are attached to windows of vehicles such as automobiles have been widely used for the purpose of UV protection, privacy protection, glass scattering prevention, decoration, and the like.

  As a window film construction method, it is easy to reattach and reposition, so in general, after spraying a liquid containing a surfactant on the glass surface to which the window film is attached, apply pressure with a spatula or the like. A method of extruding air or moisture between the window film and the glass surface and sticking the window film to the glass surface is employed (see, for example, Patent Document 1).

  However, conventionally, when a predetermined time elapses after the window film is adhered, white turbidity may occur on the adhered surface.

JP 2015-229303 A

  The objective of this invention is providing the window film for vehicles which can prevent generation | occurrence | production of the cloudiness after sticking effectively.

Such an object is achieved by the present invention described in the following (1) to (7).
(1) a base material;
With an adhesive layer,
The vehicle window film, wherein the pressure-sensitive adhesive layer has a storage elastic modulus at 25 ° C. of 1.0 × 10 ⁵ Pa or more.

  (2) The vehicle window film according to (1), wherein the pressure-sensitive adhesive layer is made of a material including an acrylic pressure-sensitive adhesive.

  (3) The window film for vehicles according to (1) or (2) above, wherein a glass transition point of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is −25 ° C. or higher.

  (4) The vehicle window film according to any one of (1) to (3), wherein the substrate is made of a material containing polyethylene terephthalate.

  (5) The vehicle window film according to any one of (1) to (4), wherein a hard coat layer is provided on a surface of the substrate opposite to the surface on which the pressure-sensitive adhesive layer is provided. .

  (6) The vehicle window film according to any one of (1) to (5), wherein the vehicle window film is attached to an adherend having a curved surface portion.

  (7) The vehicle window film according to (6), wherein the vehicle window film is attached to the concave curved surface portion.

  ADVANTAGE OF THE INVENTION According to this invention, the window film for vehicles which can prevent generation | occurrence | production of the cloudiness after sticking can be provided.

It is a longitudinal cross-sectional view which shows suitable embodiment of the window film for vehicles of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 is a longitudinal sectional view showing a preferred embodiment of the vehicle window film of the present invention.

  By the way, as a construction method of a window film for a vehicle such as an automobile, since it is easy to reattach and reposition, generally, after spraying a liquid containing a surfactant on the glass surface to which the window film is attached, While applying pressure with a spatula or the like, a method of extruding air or moisture between the window film and the glass surface to stick the window film on the glass surface is employed.

  However, conventionally, when a predetermined time elapses after the window film is adhered, white turbidity may occur on the adhered surface.

In order to solve such problems, the present inventor has conducted intensive research. As a result, the present invention has been achieved. That is, the vehicle window film of the present invention includes a base material and an adhesive layer, and the storage elastic modulus at 25 ° C. of the adhesive layer is 1.0 × 10 ⁵ Pa or more. .

  Thereby, the window film for vehicles which can prevent generation | occurrence | production of the cloudiness after sticking can be provided. This is considered to be because the surfactant can be efficiently removed from between the adherend and the vehicle window film by the pressure applied during the sticking.

  On the other hand, when the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer is less than the lower limit value, the occurrence of white turbidity after sticking cannot be effectively prevented. In particular, when an anionic surfactant that is an inexpensive surfactant is used, the frequency of occurrence of the above-described white turbidity problem increases rapidly.

  The storage elastic modulus is 1 Hz at 25 ° C. using a viscoelasticity measuring device (for example, MCR300 manufactured by Anton Paar) for a test piece of a cylindrical pressure-sensitive adhesive layer having a diameter of 8 mm and a thickness of 3 mm. Thus, it can be measured by a torsional shear method.

The vehicle window film 10 of the embodiment shown in FIG. 1 also includes a substrate 1 and an adhesive layer 2, and the storage elastic modulus at 25 ° C. of the adhesive layer 2 is 1.0 × 10 ⁵ Pa or more. is there.

The storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer 2 may be 1.0 × 10 ⁵ Pa or more, preferably 1.2 × 10 ⁵ Pa or more and 8.0 × 10 ⁵ Pa or less. It is more preferably 4 × 10 ⁵ Pa or more and 5.0 × 10 ⁵ Pa or less, and further preferably 1.5 × 10 ⁵ Pa or more and 3.5 × 10 ⁵ Pa or less.

  Thereby, the effects of the present invention as described above are more remarkably exhibited. Moreover, the adhesive force of the window film 10 for vehicles with respect to a to-be-adhered body can be made more excellent because the storage elastic modulus in 25 degreeC of the adhesive layer 2 is below the said upper limit.

<Base material>
The base material 1 is usually composed mainly of a resin material, but the constituent material of the base material 1 is not particularly limited. Examples of the constituent material of the substrate 1 include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, poly-4-methylpentene-1, and polybutene-1; polycarbonate resins; Polyvinyl sulfone resin; Polyethylene sulfide resin; Styrene resin; Acrylic resin; Polyamide resin; Cellulose resin such as cellulose acetate, etc., one or two selected from these A combination of the above can be used.

  Especially, it is preferable that the base material 1 is comprised with the material containing a polyethylene terephthalate.

  Thereby, while being able to perform construction (attachment) to the adherend (window) of window film 10 for vehicles more easily, the durability of window film 10 for vehicles can be made more excellent. . Moreover, the shape following property to the curved adherend can be made excellent.

  In the present specification, “mainly” means the highest content among the target sites.

The content of polyethylene terephthalate in the substrate 1 is preferably 80% by mass or more, more preferably 85% by mass or more, and further preferably 90% by mass or more.
Thereby, the effects as described above are more remarkably exhibited.

  The base material 1 may contain other components in addition to the resin material as described above.

  Examples of such components include colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat stabilizers, Examples thereof include a lubricant, an antistatic agent, a polymerization inhibitor, a crosslinking agent, a catalyst, a leveling agent, a thickener, and a dispersant.

  Moreover, the base material 1 may have a substantially uniform composition throughout, or may have parts having different compositions. For example, the base material 1 may be a laminate including a plurality of layers having portions with different compositions (for example, including cases where the molecular weights of the resin materials are different), and the composition is along the thickness direction. It may be made of an inclined material that changes in an inclined manner. Moreover, the base material 1 may have a thin film made of, for example, a metal material (for example, aluminum, gold, silver, copper, nickel, cobalt, chromium, tin, indium, etc.).

  The substrate 1 may be subjected to a surface treatment for improving the adhesion with the pressure-sensitive adhesive layer 2 or the hard coat layer 3.

  Examples of such surface treatment include a method of applying an easily adhesive resin such as polyester, acrylic and polyurethane, and corona treatment.

  The thickness of the substrate 1 is not particularly limited, but is preferably 3 μm or more and 300 μm or less, more preferably 5 μm or more and 200 μm or less, and even more preferably 10 μm or more and 100 μm or less.

  Thereby, while being able to make the durability of the window film 10 for vehicles more excellent, construction (sticking) to the to-be-adhered body of the window film 10 for vehicles can be performed more easily. In addition, the shape followability to a curved adherend and the like can be further improved.

<Adhesive layer>
An adhesive layer 2 is provided on the first surface 11 side which is one surface of the substrate 1.
Thereby, the window film 10 for vehicles can be suitably affixed on a to-be-adhered body.

  Although the adhesive layer 2 should just satisfy the conditions about the storage elastic modulus mentioned above, it is preferable to satisfy the following conditions.

  For example, the glass transition point of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2 is preferably −25 ° C. or higher, more preferably −20 ° C. or higher, and further preferably −18 ° C. or higher.

  Thereby, generation | occurrence | production of the cloudiness after sticking can be prevented more effectively. This is considered to be because the surfactant can be more efficiently removed from between the adherend and the vehicle window film 10 by the pressure applied during the sticking.

As an adhesive which comprises the adhesive layer 2, an acrylic adhesive, a synthetic rubber adhesive, a urethane adhesive, a silicone adhesive, etc. are mentioned, for example.
Among these, acrylic pressure-sensitive adhesives are particularly preferable from the viewpoint of weather resistance and the like.

  The acrylic pressure-sensitive adhesive only needs to contain an acrylic monomer as a constituent monomer, but the ratio of the acrylic monomer to the total monomers constituting the acrylic pressure-sensitive adhesive is 50% by mass. Preferably, it is 70 mass%, and it is still more preferable that it is 90 mass%.

  As the monomer constituting the acrylic pressure-sensitive adhesive, there are a polymerizable monomer having no crosslinkable functional group and a polymerizable monomer having a crosslinkable functional group, and as a polymerizable monomer having no crosslinkable functional group, Examples include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and the like. Examples of the polymerizable monomer having a crosslinkable functional group include carboxyl group-containing monomers such as (meth) acrylic acid; 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4- Hydroxybutyl (meth) acrylate, 6-hydroxyhexyl Hydroxyl group-containing monomers such as hydroxyalkyl (meth) acrylates such as (meth) acrylate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, Amide group-containing monomers such as N-butoxymethyl (meth) acrylamide and N-hydroxyethylacrylamide; amino groups such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and t-butylaminoethyl (meth) acrylate Monomers; Glycidyl group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; Cyano group-containing monomers such as acrylonitrile and methacrylonitrile; Phosphoric acid group-containing monomers such as liloyl phosphate; Isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate; (meth) acryloylmorpholine, and the like, and one or more selected from these are used in combination. be able to.

  In particular, the acrylic pressure-sensitive adhesive preferably contains 2-ethylhexyl acrylate, methyl acrylate and acrylic acid as constituent monomers.

  Thereby, the adhesive layer 2 can more easily satisfy the conditions for the storage elastic modulus described above, while making the adhesion of the vehicle window film 10 to the adherend particularly excellent. The occurrence of the problems as described above can be more suitably prevented.

The content of 2-ethylhexyl acrylate in all the constituent monomers of the acrylic pressure-sensitive adhesive (acrylic polymer) is preferably 25% by mass to 60% by mass, and more preferably 30% by mass to 55% by mass. Is more preferable.
Thereby, the effects as described above are more remarkably exhibited.

The content of acrylic acid in all constituent monomers of the acrylic pressure-sensitive adhesive (acrylic polymer) is preferably 1% by mass or more and 12% by mass or less, and preferably 2% by mass or more and 9% by mass or less. More preferred.
Thereby, the effects as described above are more remarkably exhibited.

The content of methyl acrylate in all the constituent monomers of the acrylic pressure-sensitive adhesive (acrylic polymer) is preferably 30% by mass to 75% by mass, and more preferably 42% by mass to 68% by mass. More preferred.
Thereby, the effects as described above are more remarkably exhibited.

  Moreover, as a crosslinking agent which comprises an acrylic adhesive, an isocyanate type crosslinking agent, an epoxy-type crosslinking agent, and a metal chelate type crosslinking agent are preferable.

  Examples of the isocyanate-based crosslinking agent include biuret bodies such as tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, isocyanurate bodies, and adduct bodies.

  Examples of the epoxy-based crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine and 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane.

  Examples of the metal chelate crosslinking agent include aluminum trisacetylacetonate and titanium tetraacetylacetonate.

  Thereby, the adhesive layer 2 can more easily satisfy the conditions for the storage elastic modulus described above, while making the adhesion of the vehicle window film 10 to the adherend particularly excellent. The occurrence of the problems as described above can be more suitably prevented.

  Specific examples of the synthetic rubber adhesive include styrene-butadiene rubber, polyisobutylene rubber, isobutylene-isoprene, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene block copolymer, and the like. Is mentioned.

  Specific examples of the urethane pressure-sensitive adhesive include those obtained by reacting a polyester polyol or polyether polyol and a polyisocyanate compound.

  Specific examples of the silicone pressure-sensitive adhesive include those containing silicone rubber and silicone resin.

  The pressure-sensitive adhesive layer 2 only needs to be mainly composed of a pressure-sensitive adhesive, and may contain components other than the pressure-sensitive adhesive.

  Such components include, for example, UV absorbers, tackifiers, fillers, softeners, antioxidants, light stabilizers, crosslinking agents, colorants, modifiers, rust inhibitors, flame retardants, hydrolysis Examples thereof include an inhibitor, a surface lubricant, a corrosion inhibitor, a heat stabilizer, a lubricant, an antistatic agent, a polymerization inhibitor, a catalyst, a leveling agent, a thickener, a dispersant, an antifoaming agent, and a surfactant.

  In particular, the durability of the vehicle window film 10 can be further improved by including an ultraviolet absorber.

  Examples of the ultraviolet absorber include hydroxyphenyl triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

  Examples of hydroxyphenyl triazine-based ultraviolet absorbers include 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3,5-triazine, 2,4, 6-tris (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris [2-hydroxy-4- (3-butoxy-2-hydroxypropyloxy) phenyl] -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine and the like.

  Examples of the benzophenone ultraviolet absorber include 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, and 2,2 ′, 4,4′-tetrahydroxybenzophenone. 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-). tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-tert-amyl-5′-isobutylphenyl) -5-chlorobenzotriazole, 2- (2 ′ -Hydroxy-3'-isobutyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-isobutyl-5'-propylphenyl) -5-chlorobenzotriazole, 2- ( 2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'- Butylphenyl) benzotriazole, 2- [2'-hydroxy-5 '- (1,1,3,3-tetramethylbutyl) phenyl] benzotriazole.

For example, the pressure-sensitive adhesive layer 2 is formed on the substrate 1 by applying a liquid composition (coating solution) for forming the pressure-sensitive adhesive layer 2 by various coating methods such as roll coating, knife coating, die coating, bar coating, and gravure coating. It can carry out by apply | coating to.
The adhesive layer 2 can be formed by solidifying the coating film of the coating liquid.

  The coating liquid may have a composition different from that of the pressure-sensitive adhesive layer 2. For example, after coating the coating liquid, the contained solvent may be removed, or the degree of polymerization and the degree of crosslinking may be different by advancing a curing reaction and a crosslinking reaction.

  The pressure-sensitive adhesive layer 2 may be once formed on a release liner and then bonded to the substrate 1.

The thickness of the pressure-sensitive adhesive layer 2 is not particularly limited, but is preferably 2 μm or more and 100 μm or less, and more preferably 3 μm or more and 30 μm or less.
Thereby, the shape followability etc. to the curved adherend can be made more excellent.

<Hard coat layer>
In the illustrated configuration, the hard coat layer 3 is provided on the second surface 12 side, which is the surface opposite to the surface (first surface 11) on which the adhesive layer 2 of the substrate 1 is provided.

  Thereby, for example, the surface hardness, scratch resistance, weather resistance, and the like of the vehicle window film 10 can be further improved.

  Examples of the constituent material of the hard coat layer 3 include siloxane compounds (silicone compounds), phosphazene resins, acrylic resins, urethane resins, melamine resins, and epoxy resins.

  The hard coat layer 3 can be formed, for example, by applying a hard coat agent-containing coating solution onto the base material 1 using a bar coat, a gravure coat, or the like, and heating and curing.

  The thickness of the hard coat layer 3 is not particularly limited, but is preferably 0.05 μm or more and 30 μm or less, more preferably 0.2 μm or more and 25 μm or less, and further preferably 1.0 μm or more and 10 μm or less. preferable.

  Thereby, while being able to make the durability of the window film 10 for vehicles more excellent, construction (sticking) to the to-be-adhered body of the window film 10 for vehicles can be performed more easily. In addition, the shape followability to a curved adherend and the like can be further improved.

  Further, a bonding layer (not shown) for bonding them may be provided between the base material 1 and the hard coat layer 3.

  Thereby, the adhesiveness of the base material 1 and the hard-coat layer 3 can be made especially excellent, and the durability of the window film 10 for vehicles can be made excellent.

  As a constituent material of the bonding layer, for example, a polyester resin or an acrylic resin can be suitably used.

  The thickness of the bonding layer is not particularly limited, but is preferably 0.01 μm or more and 15 μm or less, more preferably 0.05 μm or more and 10 μm or less, and further preferably 0.1 μm or more and 1 μm or less.

  The vehicle window film 10 is preferably attached to an adherend having a curved surface portion.

  In the past, when a window film was attached to such an adherend, the above-described problem of white turbidity occurred at a higher frequency. Even when a vehicle window film is stuck on the body, the occurrence of the cloudiness problem can be sufficiently prevented. That is, when the adherend has a curved surface portion, the effect of the present invention is more remarkably exhibited.

  Further, when the curvature radius of the curved surface portion (minimum curvature radius at the portion where the vehicle window film is attached) is relatively small (for example, when the minimum curvature radius is 2 m or less), the above-described problem occurs. Although it occurred more frequently, according to the present invention, even when a vehicle window film is adhered to the adherend as described above, the occurrence of the cloudiness problem can be sufficiently prevented. it can.

The vehicle window film 10 is preferably affixed to the concave curved surface portion.
In the past, when a window film was attached to such an adherend, the above-described problem of white turbidity occurred at a higher frequency. Even when a vehicle window film is stuck on the body, the occurrence of the cloudiness problem can be sufficiently prevented. That is, when the adherend has a curved surface portion, the effect of the present invention is more remarkably exhibited.

  Although the thickness of the window film 10 for vehicles is not specifically limited, It is preferable that they are 17 micrometers or more and 400 micrometers or less, It is more preferable that they are 25 micrometers or more and 260 micrometers or less, It is further more preferable that they are 35 micrometers or more and 150 micrometers or less.

  Thereby, while being able to make the durability of the window film 10 for vehicles more excellent, construction (sticking) to the to-be-adhered body of the window film 10 for vehicles can be performed more easily. In addition, the shape followability to a curved adherend and the like can be further improved.

  The vehicle window film 10 is a liquid containing a surfactant and is adhered in a state where the adherend is wet. Thereby, the delicate position adjustment etc. of the window film 10 for vehicles can be performed suitably. Moreover, workability | operativity improves and the remaining of the bubble etc. between a to-be-adhered body and the window film 10 for vehicles can be prevented suitably.

  Examples of the surfactant contained in the liquid include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. Among them, anionic surfactants are advantageous in that they are inexpensive, easy to foam, and easy to remove dirt.On the other hand, conventionally, when an anionic surfactant is used, there is a problem of cloudiness as described above. It was more prominent. On the other hand, in the present invention, even when a liquid containing an anionic surfactant is used, it is possible to sufficiently prevent the above-described problem from occurring. Therefore, when the liquid contains an anionic surfactant, the effect of the present invention is more remarkably exhibited.

The content of the surfactant in the liquid is preferably 0.1% by mass or more and 10% by mass or less.
Thereby, the effects as described above are more remarkably exhibited.

  The method of wetting the adherend with the liquid is not particularly limited, and examples thereof include a method of spraying the liquid on the entire pasting site using a sprayer or the like.

  The vehicle window film 10 is placed on the adherend wetted with the liquid containing the surfactant and positioned, and then the surface of the vehicle window film 10 placed on the adherend is rubbed.

  Thus, excessive liquid existing between the adherend and the vehicle window film 10 is removed, and an unintentional displacement of the vehicle window film 10 is prevented, and the adherend and the vehicle window film 10 are removed. Can be brought into close contact with each other.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to these.

  For example, the vehicle window film may have a configuration other than that described above.

  Examples of such a structure include a conductive layer, an antistatic layer, a gas barrier layer, an easy adhesion layer (adhesion layer), an antifouling layer, a deodorizing layer, a droplet layer, a slippery layer, an abrasion resistant layer, and a reflective layer. Examples thereof include a prevention layer, an electromagnetic wave shielding layer, an ultraviolet absorption layer, an infrared absorption layer, a printing layer, a fluorescent light emitting layer, a hologram layer, an infrared cut layer (metal layer, liquid crystal layer), and a colored layer.

  The surface of the pressure-sensitive adhesive layer (the surface opposite to the surface facing the substrate) may be covered with a release liner. This makes it more effective that dust or the like adheres to the adhesive layer or that the adhesive layer adheres to unintentional parts during storage or transportation of the vehicle window film. Can be prevented. When the vehicle window film is adhered to the adherend, the release liner may be peeled off to expose the pressure-sensitive adhesive layer.

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples. In the following description, the treatment that does not particularly indicate the temperature condition is performed at room temperature (25 ° C.) and a relative humidity of 50%. Moreover, what does not show temperature conditions in particular also about various measurement conditions is a numerical value in room temperature (25 degreeC) and 50% of relative humidity.

[1] Manufacture of vehicle window film (Example 1)
First, a polyethylene terephthalate film having a thickness of 50 μm is prepared as a base material, and an ultraviolet curable acrylic hard coat material is applied to one side (second surface) of the bar coating method so that the dry film thickness becomes 3 μm. The film was applied and irradiated with ultraviolet rays having an integrated light quantity of 200 mJ / cm ² . Thereby, a hard coat layer was formed.

  Next, after coating the composition containing the acrylic pressure-sensitive adhesive on the surface (first surface) opposite to the surface on which the hard coat layer of the substrate is provided, at 100 ° C. Dry for 3 minutes to form a 7 μm pressure-sensitive adhesive layer, and a 38 μm-thick polyethylene terephthalate release liner coated with silicone on the pressure-sensitive adhesive layer. A thickness of 98 μm) was obtained.

  The content of 2-ethylhexyl acrylate in all the constituent monomers of the acrylic pressure-sensitive adhesive (acrylic polymer) is 45% by mass, the content of methyl acrylate is 49% by mass, and the content of acrylic acid is 6% by mass. there were. As a cross-linking agent, 0.1 part by mass of 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane was added to 100 parts by mass of the solid content of the acrylic polymer. Moreover, the glass transition point (Tg) of the acrylic pressure-sensitive adhesive was −17.7 ° C. The acrylic pressure-sensitive adhesive had a weight average molecular weight of 500,000.

Moreover, a test piece of a cylindrical pressure-sensitive adhesive layer having a diameter of 8 mm and a thickness of 3 mm was separately prepared, and the test piece was measured at 1 Hz and 25 ° C. using a viscoelasticity measuring apparatus (MCR300, manufactured by Anton Paar). When measured by the torsional shear method under the environment, the storage elastic modulus was 1.6 × 10 ⁵ Pa.

(Examples 2, 3, and 4)
The vehicle window film is the same as in Example 1 except that the composition of the vehicle window film is shown in Table 1 by adjusting the composition and coating amount of the composition used for forming the adhesive layer. Manufactured.

(Comparative Example 1)
A vehicle window film was produced in the same manner as in Example 1 except that the composition of the vehicle window film was adjusted as shown in Table 1 by adjusting the composition of the composition used for forming the pressure-sensitive adhesive layer.

Table 1 summarizes the configurations of the window films for vehicles according to the above examples and comparative examples.
In Table 1, polyethylene terephthalate is represented by PET, 2-ethylhexyl acrylate is represented by 2EHA, methyl acrylate is represented by MA, and acrylic acid is represented by Ac.

[2] Evaluation The following evaluations were performed on the vehicle window films of the above Examples and Comparative Examples.

<Appearance>
Using a nebulizer, a 10% by mass aqueous solution of an anionic surfactant was sprayed on the entire interior surface (surface having a concave curved surface) of an automotive windshield having a curved surface (minimum curvature radius 2 m).

  After that, a vehicle window film is placed on an automotive windshield wetted with a liquid containing a surfactant and positioned, and then the surface of the vehicle window film is rubbed with a rubber squeegee to remove the vehicle window film. Adhered to the windshield for automobiles.

  After 168 hours had passed from the sticking, the automotive windshield with the vehicle window film attached was visually observed and evaluated according to the following criteria.

A: No cloudiness is observed.
C: Slight cloudiness is observed.
E: White turbidity is noticeable.

<Adhesive strength>
Using a sprayer, a 10% by mass aqueous solution of an anionic surfactant was sprayed on the entire surface of a flat plate made of glass.

  After that, the vehicle window film is placed and positioned on a flat plate wetted with a liquid containing a surfactant, and then the surface of the vehicle window film is rubbed with a rubber squeegee to make the vehicle window film into a flat plate. Sticked.

  After 168 hours had passed from the sticking, the 90-degree peeling adhesive strength defined in JIS Z0237: 2009 was measured and evaluated according to the following criteria.

A: Adhesive strength is 6 N / 25 mm or more.
B: Adhesive strength is 4 N / 25 mm or more and less than 6 N / 25 mm.
C: Adhesive strength is 3 N / 25 mm or more and less than 4 N / 25 mm.
D: Adhesive strength is 2 N / 25 mm or more and less than 3 N / 25 mm.
E: Adhesive strength is less than 2 N / 25 mm.
These results are summarized in Table 2.

  As is apparent from Table 2, excellent results were obtained in the present invention, whereas satisfactory results were not obtained in the comparative example.

DESCRIPTION OF SYMBOLS 10 ... Window film for vehicles 1 ... Base material 11 ... 1st surface 12 ... 2nd surface 2 ... Adhesive layer 3 ... Hard-coat layer

Claims (7)

A substrate;
With an adhesive layer,
The vehicle window film, wherein the pressure-sensitive adhesive layer has a storage elastic modulus at 25 ° C. of 1.0 × 10 ⁵ Pa or more.   The vehicle window film according to claim 1, wherein the pressure-sensitive adhesive layer is made of a material containing an acrylic pressure-sensitive adhesive.   The window film for vehicles according to claim 1 or 2 whose glass transition point of the adhesive which constitutes said adhesive layer is -25 ° C or more.   The vehicle window film according to any one of claims 1 to 3, wherein the base material is made of a material containing polyethylene terephthalate.   The vehicle window film according to any one of claims 1 to 4, further comprising a hard coat layer on a surface opposite to the surface on which the pressure-sensitive adhesive layer of the base material is provided.   The vehicle window film according to any one of claims 1 to 5, wherein the vehicle window film is attached to an adherend having a curved surface portion.   The vehicle window film according to claim 6, wherein the vehicle window film is adhered to the concave curved surface portion.

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