JP2020002256A - High weather resistant adsorptive film - Google Patents

Abstract

To provide an adsorptive film capable of being laminating on or removing from an adherend such as an information display screen or the like of a display panel, having no discoloration and modification in outdoor use for long time, and high weather resistance, and sufficient adhesion force of a substrate and an adsorption layer.SOLUTION: There is provided an adsorptive film by directly laminating an adsorption layer to a resin layer, in which the resin layer comprises at least a hydroxyl group-containing acrylic resin and a curing agent, and is manufactured by being cured by heat, and an adsorptive film having high weather resistance, and sufficient adhesion force of the resin layer and the adsorption layer laminated can be provided by setting a ratio of hydroxyl group in the hydroxyl group-containing acrylic resin and an isocyanate group (NCO group) in the curing agent at a specific value.SELECTED DRAWING: Figure 1

Description

The present invention has a high weather resistance, which can be attached to or detached from an adherend such as an information display screen of a display panel, and is not discolored or deteriorated during long-term outdoor use, and has a base material and an adsorption layer. This is related to an adsorption film that has sufficient adhesion, and more specifically, protects information display screens when used outdoors, such as liquid crystal displays, plasma displays, and organic ELs used as display devices for various electronic and electrical devices. As an object, the present invention relates to a highly weather-resistant adsorption film installed on an information display screen.

When the adsorption film is used outdoors, for example, when used as a protective film for a display installed outdoors, it is necessary that the weather resistance be practically sufficient in addition to the function of a normal protective film. A polyethylene terephthalate (PET) film is often used as a base material for a protective film of a display presumed for indoor use because of its price, availability, and physical properties (strength). However, the weather resistance of the PET film is not high, and it is known that the film is yellowed by exposure to direct sunlight outdoors, particularly ultraviolet rays, and the film strength is reduced.

An acrylic resin film is cited as a film having high weather resistance, and an acrylic resin film obtained by polymerizing (meth) acrylic acid is provided with an adhesive layer to form an adhesive film having good weather resistance. I have. (See Patent Document 1) However, the invention in the above document discloses a content relating to a pressure-sensitive adhesive and an adhesive, and does not describe a content of providing an adhering layer that can be attached or detached to an adherend.

As an adsorption layer having high weather resistance, there is an adsorption layer made of an addition reaction type silicone resin. Then, when the present inventor prepared the adsorption film by providing the adsorption layer on a commercially available acrylic resin film obtained by polymerizing (meth) acrylic acid, the adhesion between the resin film and the adsorption layer was low, and the display panel had It has been discovered that the resin film and the adsorbing layer are peeled off when being attached to and removed from an adherend such as an information display screen, which poses a practical problem.

Japanese Utility Model Publication No. 55-1876

The present invention has a high weather resistance, which can be attached to or detached from an adherend such as an information display screen of a display panel, and is not discolored or deteriorated during long-term outdoor use, and has a base material and an adsorption layer. An object of the present invention is to provide an adsorption film having a sufficient adhesive force.

The present inventors have conducted intensive studies and found that an acrylic resin layer obtained by thermosetting a hydroxyl group-containing acrylic resin and a curing agent was used as a base material, and an adsorption layer was directly laminated on the resin layer. By setting the ratio of the hydroxyl group (OH group) in the resin to the isocyanate group (NCO group) in the curing agent to a specific value, a highly weather-resistant adsorption film is obtained, and the laminated acrylic resin layer The present inventors have found that sufficient adhesion to the adsorption layer can be obtained, and have completed the present invention.

The first invention is an adsorption film obtained by directly laminating an adsorption layer on at least a resin layer, wherein the resin layer is formed by heating a hydroxyl group-containing acrylic resin and a curing agent containing two or more isocyanate groups in one molecule by heat. A cured acrylic resin layer, wherein the ratio of the hydroxyl group in the hydroxyl group-containing acrylic resin in the resin layer to the isocyanate group in the curing agent is isocyanate group / hydroxyl group = 0.25 to 3.20. It is an adsorption film characterized by the above.

A second invention is the adsorption film according to the first invention, wherein the hydroxyl group-containing acrylic resin is an acrylic polyol.

A third invention is the adsorption film according to the first invention or the second invention, wherein the resin forming the adsorption layer is an addition reaction type silicone resin.

The adsorption film of the present invention has an acrylic resin layer obtained by thermosetting a hydroxyl group-containing acrylic resin and a curing agent as a base material, and directly laminates an adsorption layer on the resin layer, and further includes a hydroxyl group-containing acrylic resin in the resin layer. By setting the ratio of the hydroxyl group to the isocyanate group in the curing agent to a specific value, a highly weather-resistant adsorption film is obtained, and the adhesion between the laminated acrylic resin layer and the adsorption layer is improved. Is what you do.

Hereinafter, the adsorption film of the present invention will be described in more detail based on its constituent elements.

(overall structure)
The adsorption film of the present invention is an adsorption film in which an acrylic resin layer obtained by thermosetting a hydroxyl group-containing acrylic resin and a curing agent is used as a base material, and an adsorption layer is directly laminated on the resin layer.

(Acrylic resin layer)
Among the constituent elements of the adsorption film of the present invention, the acrylic resin layer serving as the substrate is a resin layer obtained by curing at least a hydroxyl group-containing acrylic resin and a curing agent by heat.

(Hydroxy group-containing acrylic resin)
As the hydroxyl group-containing acrylic resin that can be used in the present invention, an acrylic polyol can be favorably used. Further, not only one kind of the hydroxyl group-containing acrylic resin but also a mixture of two or more kinds may be used.

Examples of the acrylic polyol include acrylates and / or methacrylates (hereinafter referred to as (meth) acrylates) and hydroxyacrylates and / or hydroxymethacrylates having at least one hydroxyl group in the molecule. A compound obtained by copolymerizing a compound (hereinafter referred to as a hydroxy (meth) acrylate compound) is used.

((Meth) acrylate)
Specific examples of (meth) acrylic acid esters include, for example, alkyl esters having 1 to 20 carbon atoms. Specific examples of such (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (Meth) such as hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate Alkyl acrylate; ester of (meth) acrylic acid with cycloaliphatic alcohol such as cyclohexyl (meth) acrylate; aryl (meth) acrylate such as phenyl (meth) acrylate and benzyl (meth) acrylate Can be mentioned. Such (meth) acrylates may be used alone or in combination of two or more.

(Hydroxy (meth) acrylate compound)
Specific examples of the (meth) acrylic acid hydroxy compound include one or more hydroxyl groups in the molecule that react with the curing agent, and specifically include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxypropyl acrylate. Examples include hydroxy acrylate compounds such as hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, and pentaerythritol triacrylate. Further, hydroxy methacrylate compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, and pentaerythritol trimethacrylate may be mentioned. These hydroxy acrylate compounds and hydroxy methacrylate compounds can be used alone or in combination of two or more.

As the curing agent that can be used for curing the acrylic resin layer of the present invention, a curing agent that can thermally cure the hydroxyl-containing acrylic resin is used. As a curing agent that can be thermally cured, an isocyanate-based compound is preferable because flexibility of the resin layer after curing can be obtained.

As the curing agent for the isocyanate compound, it is necessary to cure the hydroxyl group of the hydroxyl group-containing acrylic resin and the NCO group in the isocyanate compound by addition polymerization by heat. Those containing two or more are preferably used. For example, aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, and aliphatic diisocyanates such as butylene diisocyanate, hexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate And alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, norbornene diisocyanate, and isophorone diisocyanate. Among them, aliphatic and alicyclic diisocyanates are preferably used because they are non-yellowing type and a resin layer can easily obtain appropriate flexibility, and hexamethylene diisocyanate and isophorone diisocyanate are particularly preferable. Note that the type of the isocyanate compound is not necessarily limited to these.

In the present invention, as the curing agent, one of the above compounds may be used alone, or two or more of them may be used in combination. When two or more curing agents of the same type are used in combination, two or more curing agents of the same type (for example, two types of aliphatic diisocyanates) may be combined, or one or more types of curing agents of different types (for example, aliphatic diisocyanates may be used). One type and one type of alicyclic diisocyanate may be combined.

The thickness of the acrylic resin layer used as the base material of the present invention is preferably 5 μm to 200 μm, more preferably 10 μm to 150 μm. If the thickness of the resin layer is less than 5 μm, the strength as an adsorption film is insufficient, and the resin layer may be damaged when attached to or detached from an adherend such as an information display screen. If it exceeds 200 μm, the flexibility as a base material is lost,
Processing when laminating the adsorption layer on the substrate becomes difficult.

In the present invention, the ratio of the hydroxyl group of the hydroxyl group-containing acrylic resin in the acrylic resin layer to the isocyanate group in the curing agent is preferably isocyanate group / hydroxyl group = 0.25 to 3.20. Within this range, the strength of the cured acrylic resin layer base material is sufficient, and unreacted hydroxyl groups remain on the resin layer surface, so that the adsorption layer has SiH groups that react with hydroxyl groups in the adsorption layer. This makes it possible for the functional groups and the hydroxyl groups in the resin layer to react with each other and bond, thereby obtaining sufficient adhesion between the resin layer and the adsorption layer. If the ratio is less than 0.25, curing will be insufficient and the resin layer strength will be insufficient. Further, it is not preferable because the flexibility as the base material is inferior and the substrate is easily cracked. If the ratio exceeds 3.20, the amount of hydroxyl groups remaining on the surface of the resin layer decreases, and sufficient adhesion to the adsorption layer cannot be obtained.

The acrylic resin layer serving as the base material of the present invention may contain various additives according to the purpose. For example, an ultraviolet absorber for the purpose of further improving weather resistance, a pigment for the purpose of coloring, a coloring agent such as a dye, an inorganic or organic particle for the purpose of giving unevenness to the surface shape, and the like, but not necessarily. It is not limited to these.

(Adsorption layer)
The adsorption layer of the present invention can be attached to or detached from an adherend, and is made of a resin such as natural or synthetic rubber, silicone resin, urethane resin, acrylic resin, or the like, and is cured with a curing agent. However, an addition-reaction type silicone resin can be used particularly preferably because it can have a functional group capable of reacting with a hydroxyl group and has weather resistance and flexibility.

When the addition reaction type silicone resin is used as the adsorption layer of the present invention, a polyorganosiloxane having two or more vinyl groups in one molecule and an organohydrogenpolysiloxane having SiH groups as a curing agent are used. Those obtained by thermosetting by an addition reaction are preferably used. By setting the ratio of the polyorganosiloxane and the organohydrogenpolysiloxane having the SiH group to a specific value, it is possible to obtain an adsorption layer which is suitable as an adsorption layer and is made of a silicone resin having a SiH group in the adsorption layer. be able to. By reacting and bonding the SiH groups in the adsorption layer with the hydroxyl groups remaining on the surface of the substrate film made of the acrylic resin layer, a sufficient adhesion between the substrate film and the adsorption layer can be obtained.

Hereinafter, the adsorption layer using a silicone resin will be described in more detail.

(Silicone resin adsorption layer)
As the properties of the silicone resin used for the adsorption layer of the present invention, the transparency is high, the rubber has flexibility, and the surface of the adsorption layer is along the surface of the adherend even on the surface of the adherend. Is required. Further, at the time of peeling, it is required that peeling can be easily performed with a small peeling force. Further, in order to provide an adsorbing layer with a thickness of at least 5 μm or more and only by application and heat treatment without using a basis weight processing method, at the time of a curing reaction of the silicone composition, a temperature of 150 ° C. or less under a platinum catalyst or the like. It is a low-viscosity, liquid-type polyorganosiloxane that has two or more vinyl groups in one molecule, and a SiH group as a curing agent. It is preferable to use an addition-reaction-type liquid silicone composition that is thermally cured by an addition reaction with an organohydrogenpolysiloxane having the following formula:

Examples of the diorganopolysiloxane having two or more vinyl groups in one molecule include a linear diorganopolysiloxane having vinyl groups only at both ends and a linear diorganopolysiloxane having vinyl groups at both ends and side chains. It is preferable to use at least one selected from an organopolysiloxane, a branched diorganopolysiloxane having a vinyl group only at a terminal, and a branched diorganopolysiloxane having a vinyl group at a terminal and a side chain.

One form of these diorganopolysiloxanes is a linear diorganopolysiloxane having a vinyl group only at both ends and a compound represented by the following general formula (Formula 1).

  (In the formula, R represents the following organic group, and n represents an integer.)

  (In the formula, R represents the following organic group, and n and m represent integers.)

The organic group (R) bonded to the silicon atom other than the vinyl group may be of a different kind or the same kind. Specific examples include an alkyl group such as a methyl group, an ethyl group and a propyl group, and an aryl group such as a phenyl group and a tolyl group. Or a monovalent hydrocarbon group excluding the same or different unsubstituted or substituted aliphatic unsaturated groups in which part or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms, cyano groups, etc. Preferably, at least 50 mol% of the diorganopolysiloxane is a methyl group. The diorganopolysiloxane may be used alone or as a mixture of two or more.

The linear diorganopolysiloxane having vinyl groups at both ends and side chains is a compound in which a part of R in the above general formula (Formula 1) is a vinyl group. The branched polyorganosiloxane having a vinyl group only at the terminal is a compound represented by the above general formula (Formula 2). The branched polyorganosiloxane having a vinyl group at a terminal and a side chain is a compound in which a part of R in the general formula (Formula 2) is a vinyl group.

The weight average molecular weight of the diorganopolysiloxane having two or more vinyl groups in one molecule is preferably in the range of 20,000 to 700,000. If the weight-average molecular weight of the diorganopolysiloxane is less than 20,000, the curability will decrease and the adsorbing power to the adherend will decrease. On the other hand, if it exceeds 700,000, the viscosity of the composition becomes too high, which makes it difficult to stir during production.

Here, as an example of the curing agent used for the curing reaction of the silicone resin, an organohydrogenpolysiloxane can be mentioned. The organohydrogenpolysiloxane has at least three hydrogen atoms bonded to a silicon atom in one molecule, but from a practical point of view, a compound having two ≡SiH bonds in a molecule has a total amount of 50%. % By weight, and the remainder preferably contains at least three ≡SiH bonds in the molecule. As the shape of the molecule, a linear, branched or cyclic molecule can be used.

The molar ratio (A) / (B) of the SiH group (B) in the organohydrogenpolysiloxane to the vinyl group (A) in the diorganopolysiloxane having a vinyl group is in the range of 1.0 to 2.0. It is preferable to mix them so that If the molar ratio (A) / (B) is less than 1.0, the cured density becomes insufficient, and the cohesive force and the holding power may be reduced accordingly. Therefore, it is difficult to obtain a sufficient adhesive force and tackiness, and it is difficult to obtain a sufficient adhesive force due to a bond between a hydroxyl group and a SiH group on the surface of the base film made of the acrylic resin layer.

The addition reaction catalyst used for the curing reaction includes chloroplatinic acid, an alcohol solution of chloroplatinic acid, a reactant of chloroplatinic acid and an alcohol, a reactant of chloroplatinic acid and an olefin compound, chloroplatinic acid and a vinyl group-containing siloxane. , A platinum-olefin complex, a platinum-vinyl group-containing siloxane complex, a rhodium complex, a ruthenium complex, and the like. Further, those obtained by dissolving and dispersing these in a solvent such as isopropanol or toluene, or silicone oil may be used. The cured adsorption layer has flexibility like silicone rubber, and this flexibility facilitates close contact with the adherend.

The addition amount of the addition reaction catalyst is preferably 5 to 2,000 ppm, particularly preferably 10 to 500 ppm as a noble metal component based on 100 parts by weight of the total silicone composition. If it is less than 5 ppm, the curability will be reduced, the cured density will be reduced, and the holding power may be reduced. If it exceeds 2,000 ppm, the usable time of the coating liquid may be shortened.

Commercially available shapes of the silicone composition according to the present invention include a solventless type, a solvent type, and an emulsion type, and any type can be used. Above all, the solvent-free type is very advantageous in terms of safety, hygiene and air pollution since no solvent is used. However, even if it is a non-solvent type, an aromatic hydrocarbon solvent such as toluene or xylene, or a fat such as hexane, heptane, octane, or isoparaffin may be used as needed to adjust the viscosity to obtain a desired film thickness. Aromatic hydrocarbon solvents, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and isobutyl acetate, ether solvents such as diisopropyl ether and 1,4-dioxane, or mixed solvents thereof Is done.

The amount of the solvent to be added is preferably 20 to 1,000 parts by weight, particularly preferably 25 to 900 parts by weight, based on 100 parts by weight of the total of the silicone composition. If the amount is less than 20 parts by weight, the adhesion between the adsorbing layer and the base material may be reduced to cause peeling. If the amount exceeds 1,000 parts by weight, the viscosity of the coating liquid of the silicone composition becomes too low. During the period from after to curing, the applied adsorption layer partially flows, and the smoothness of the surface of the adsorption layer is reduced.

The properties of the adsorption layer of the present invention are required to have rubber-like flexibility and to secure adhesion by following irregularities on the surface of the adherend at the time of sticking to the adherend. For example, when used as a protective member for the information display screen, the thickness of the adsorption layer is at least 5 μm or more, and usually 10 to 100 μm, in order to secure a shearing force in the direction of the adhesion surface of the adsorption layer to the adherend. Preferably, it is 20 to 50 μm. If it is less than 5 μm, the shearing force of the protective member in the direction of the contact surface with the adherend cannot be secured, and the protective member is easily peeled off from the adherend, especially during long-term application. If the thickness of the adsorbing layer exceeds 100 μm, the amount of the resin constituting the adsorbing layer is increased, and the production cost of the adsorbing film is increased.

As a method for forming the adsorption layer in the present invention, a known method such as a method of applying a resin solution having a viscosity adjusted by dissolving in an organic solvent or a method of dispersing and applying in water can be used. As the organic solvent, a general organic solvent can be used without any particular limitation. Examples include, but are not limited to, organic solvents such as acetone, methyl ethyl ketone, benzene, toluene, and ethyl acetate.

 Examples of the method for coating the adsorption layer of the present invention include a comma knife coater, a die coater, and a reverse coater.

(Separator)
In the present invention, a separator made of a plastic film is preferably used by adhering to the surface of the adsorption layer for the purpose of preventing dirt and foreign matter from adhering to the surface of the adsorption layer and improving the handling of the adsorption film.

A plastic film is used for the separator of the adsorption film of the present invention. For example, a polyester film, a polypropylene film, a polyethylene film, a polycarbonate film, a polystyrene film and the like can be mentioned. Among them, a polyester (PET) film having excellent productivity and processability can be preferably used. Further, such a polyester film includes a biaxially stretched film, a uniaxially stretched film, and a non-stretched film, and any of them can be used. In particular, a biaxially stretched film is generally used and can be preferably used. As the thickness of the plastic film, 25 to 200 μm is preferably used. If the thickness is less than 25 μm, the film strength is insufficient, and problems such as insufficient protection performance and breakage of the film upon peeling occur. On the other hand, if the thickness is more than 200 μm, there arises a problem that the film becomes expensive.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, “parts” in each example indicates parts by weight unless otherwise specified.

(Examples 1 to 15, Comparative Examples 1 to 3)
On the release-treated surface of a 100-μm-thick release-treated PET film, various resin layer coating solutions of Examples and Comparative Examples mixed according to the formulations shown in Table 1 were dried. Is applied to adjust to each value of the above, dried by heating at 65 ° C. for 2 minutes to remove the organic solvent, and then heated and cured at 150 ° C. for 4 minutes to obtain a base material composed of various resin layers. Produced.

Silicone resin adsorption layer (Examples 1 to 15, Comparative Examples 1 to 3)
On the resin layer, the following silicone resin adsorption layer coating solution was applied by a die coater and provided, and then heated and cured in an oven at 150 ° C. for 100 seconds. Adsorption layers having the respective thicknesses described in Examples 1 to 3 were formed.
(Coating liquid for silicone resin adsorption layer)
68.59 parts (weight average molecular weight Mw: 540,000) of a linear diorganopolysiloxane having a vinyl group at a molecular end and a side chain / 0.41 part (weight) of a solventless organohydrogensiloxane-diorganosiloxane copolymer Average molecular weight Mw: 2,000) / Solvent-free platinum catalyst (manufactured by Shin-Etsu Polymer, PL-56) 1.00 parts Toluene 30.00 parts Total 100.00 parts

(Examples 1 to 15, Comparative Examples 1 to 3)
A PET film having a thickness of 50 μm is provided as a separator on the surface of each of the adsorption films on which the above-mentioned adsorption layers are formed to form a 100 μm release-treated PET film / resin layer / adsorption layer / 50 μm PET film. After sandwiching them with a roll (rubber roll and metal roll) and adhering them while releasing air, the 100 μm release PET film is peeled off, and an adsorption layer and a separator are laminated on one side of a hydroxyl group-containing resin layer. Got.

Table 1 shows material composition ratios and evaluation results of each of the examples and comparative examples, and each evaluation method is shown below.

(Evaluation method)
(Evaluation of adhesion between resin layer and adsorption layer)
The suction film produced above was cut, and after the separator was peeled off, the cut end was rubbed with a finger to confirm that the suction layer was peeled off.
Evaluation criteria ○: There is no peeling of the adsorption layer.
X: There is peeling of the adsorption layer.

(Evaluation of substrate flexibility)
The above-prepared base materials made of the hydroxyl-containing resins of Examples 1 to 15 and Comparative Examples 1 to 3 were peeled from the 100 μm release-treated PET film at a stage before the adsorbing layer was set, and the length was 100 mm × 25 mm in width. A test piece was prepared by cutting. When these test pieces were bent at 180 °, it was visually confirmed whether or not the base material cracked. (See Fig. 1)
Evaluation criteria ○: No cracks occurred.
×: Cracks occurred.

(Weather resistance evaluation of adsorption film)
The above-prepared adsorption film was treated with a fade meter (FAL-5B manufactured by Suga Test Instruments Co., Ltd.) for 500 hours, the transmission hue before and after the treatment was measured by L * a * b *, and Δb * = b * (after the treatment) The evaluation was -Δb * (before treatment). (Hue measuring device: Minolta CR-221)
Evaluation criteria A: Δb * is less than 0.5.
：: Δb * is 0.5 to less than 1.0.
×: Δb * is 1.0 or more.

It is a figure of the flexibility evaluation method of a substrate in the present invention.

Claims (3)

An adsorption film obtained by directly laminating an adsorption layer on at least a resin layer, wherein the resin layer is formed by heat-curing a hydroxyl-containing acrylic resin and a curing agent containing two or more isocyanate groups in one molecule. Adsorption, wherein the ratio of the hydroxyl group in the hydroxyl group-containing acrylic resin in the resin layer to the isocyanate group in the curing agent is isocyanate group / hydroxyl group = 0.25 to 3.20. the film. The adsorption film according to claim 1, wherein the hydroxyl group-containing acrylic resin is an acrylic polyol. 3. The adsorption film according to claim 1, wherein the resin forming the adsorption layer is an addition reaction type silicone resin.

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