CN114008156B - Protective film, foldable device and rollable device - Google Patents

Protective film, foldable device and rollable device Download PDF

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Publication number
CN114008156B
CN114008156B CN202180003857.7A CN202180003857A CN114008156B CN 114008156 B CN114008156 B CN 114008156B CN 202180003857 A CN202180003857 A CN 202180003857A CN 114008156 B CN114008156 B CN 114008156B
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protective film
weight
acrylate
layer
meth
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CN114008156A (en
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设乐浩司
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Nitto Denko Corp
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Nitto Denko Corp
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/25—Plastics; Metallised plastics based on macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/044—Forming conductive coatings; Forming coatings having anti-static properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • G09F9/301—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements flexible foldable or roll-able electronic displays, e.g. thin LCD, OLED
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2371/00—Characterised by the use of polyethers obtained by reactions forming an ether link in the main chain; Derivatives of such polymers
    • C08J2371/08—Polyethers derived from hydroxy compounds or from their metallic derivatives
    • C08J2371/10—Polyethers derived from hydroxy compounds or from their metallic derivatives from phenols
    • C08J2371/12—Polyphenylene oxides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2433/00—Presence of (meth)acrylic polymer
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2461/00—Presence of condensation polymers of aldehydes or ketones
    • C09J2461/006—Presence of condensation polymers of aldehydes or ketones in the substrate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2479/00—Presence of polyamine or polyimide
    • C09J2479/08—Presence of polyamine or polyimide polyimide
    • C09J2479/086—Presence of polyamine or polyimide polyimide in the substrate

Abstract

Provided is a protective film which has excellent bend recovery properties, does not damage a barrier layer even when attached to the back side of a polyimide substrate having the barrier layer, has excellent transparency, and has excellent foreign matter inspection properties. Foldable and rollable devices provided with such a protective film are provided. The protective film according to an embodiment of the present invention is a protective film directly bonded to a polyimide substrate, and includes a base material layer and a pressure-sensitive adhesive layer, wherein the base material layer does not substantially contain particles or aggregates of particles having a Ferrett diameter of 1 μm or more.

Description

Protective film, foldable device and rollable device
Technical Field
The present invention relates to protective films. The invention also relates to a foldable device provided with such a protective film and to a rollable device provided with such a protective film.
Background
The protective film is used for reinforcement of parts of various shapes, surface protection, and the like.
For example, when an Integrated Circuit (IC) or a flexible printed circuit board (FPC) is bonded to a substrate of a semiconductor element (for example, a TFT substrate or the like), thermocompression bonding is generally performed by an Anisotropic Conductive Film (ACF). In such thermocompression bonding, a protective film may be bonded to the back side of the substrate of the semiconductor element in advance for reinforcement (for example, patent document 1).
In addition, as a method for manufacturing a flexible device or a rollable device which has been developed in recent years, in general, a release layer is formed on a support substrate such as glass, a flexible or rollable film substrate is formed, a TFT substrate is formed on the film substrate, and an organic EL layer is further formed thereon. Then, the support substrate is peeled off to manufacture the flexible device and the rollable device, but the flexible display layer and the rollable display layer are very thin, and therefore, the device is defective due to handling and the like. Therefore, a protective film may be bonded to the back side in advance for reinforcement. Such a conventional protective film includes a base layer and a pressure-sensitive adhesive layer, and as the base layer, a polyester film or an acrylic resin film is considered preferable, and typically, a PET film is used (for example, a surface protective film of patent document 2, a first protective film of patent document 3).
A substrate, a flexible device, and a rollable device of a semiconductor element may be repeatedly bent, and if a protective film attached to the back side of the substrate has poor bending characteristics, the recovery after bending may be deteriorated, or at worst, the substrate may be repeatedly bent to be broken. Specifically, when the protective film is to be bonded to a bending portion (e.g., a movable bending portion of a folding member), for example, the following problems occur.
When the protective film strip is bent at an angle, a force for compressing the protective film strip acts on the bent inner diameter side, and the protective film itself is deformed to relax the force. Specifically, for example, wrinkles are likely to occur.
When the protective film strip is bent at an angle, a tensile stress acts on the bent outer diameter side. Therefore, when this stress is relaxed, lifting from the adherend occurs.
When the protective film tape is bent at an angle, the thickness of the bent portion or the stretched portion of the protective film changes greatly, and wrinkles or lifting are likely to occur even in this state. For example, when the protective film is stretched, the thickness of the protective film is significantly reduced, and the protective film is likely to float from the adherend.
The conventional protective films such as the surface protective film of patent document 2 and the first protective film of patent document 3 cannot sufficiently follow the irregularities of the corner and the curved portion. In particular, when the protective film is bonded to the movable bending portion, the protective film is repeatedly bent, and thus there is a problem that the protective film is creased (so-called "mark") at the movable bending portion.
On the other hand, when the flexible device or the rollable device is an OLED, a polyimide substrate is generally used as a substrate on which a display region or a terminal portion is to be formed. The polyimide substrate is thin and has a thickness of about 10 to 20 μm (for example, a polyimide substrate of patent document 3). Since the polyimide substrate is likely to contain moisture, a barrier layer is usually provided on the surface of the polyimide substrate on the side where the display region and the terminal portion are to be formed, in order to prevent the organic EL layer from being deteriorated by moisture. The barrier layer is made of a brittle material such as SiO or SiN, and therefore is very brittle and extremely thin, and has a thickness of about 50nm to 300nm (for example, the barrier layer of patent document 3). When a conventional protective film is bonded to the back side of a polyimide substrate having such a barrier layer, the polyimide substrate may be deformed, and the fragile and extremely thin barrier layer may be broken by the deformation.
When an Integrated Circuit (IC) or a flexible printed circuit board (FPC) is bonded to a substrate of a semiconductor element (for example, a TFT substrate) by thermocompression bonding, the bonding position is checked from the back side of the substrate and pressure bonding is performed. Therefore, transparency is required for the protective film to be attached to the back side of the substrate.
Further, the protective film is subjected to foreign matter inspection in the manufacturing process thereof. Here, in the conventional protective film, a filler is contained in a base material layer (typically, a PET film) in order to prevent blocking or the like, and there is a problem that, in a product having a non-defective level in foreign matter inspection and containing only extremely fine foreign matter having a maximum length of less than 1 μm as foreign matter, the filler is recognized as foreign matter and is determined as a defective product, and productivity is lowered.
Documents of the prior art
Patent document
Patent document 1: japanese patent No. 5600039
Patent document 2: japanese patent No. 6376271
Patent document 3: japanese patent laid-open publication No. 2017-212078
Disclosure of Invention
Problems to be solved by the invention
The present invention addresses the problem of providing a protective film that has excellent bend recovery properties, does not damage a barrier layer even when bonded to the back side of a polyimide substrate provided with the barrier layer, has excellent transparency, and has excellent foreign matter inspection properties. It is also an object of the present invention to provide a foldable device and a rollable device provided with such a protective film.
Means for solving the problems
The present inventors have conducted studies to solve the above problems. As a result, they found that: the reason why the barrier layer is damaged when the protective film is bonded to the back side of the polyimide substrate having the barrier layer is particles present in the protective film. The reason why the particles are present is considered to be a filler contained in the base layer of the protective film for preventing blocking. Further, it is considered that: if such particles can be excluded, excellent transparency and excellent foreign matter inspection can also be exhibited. Thus, it is considered that: the present inventors have completed the present invention by solving the problems of the present invention if a protective film having excellent bend recovery properties is formed by excluding the above-mentioned particles.
The protective film according to the embodiment of the present invention is a protective film directly bonded to a polyimide substrate,
which comprises a base material layer and an adhesive layer,
the base material layer does not substantially contain particles or aggregates of particles having a Ferrett diameter of 1 μm or more.
In one embodiment, the substrate layer has a top coat layer on the surface thereof opposite to the surface having the adhesive layer.
In one embodiment, the top coat layer contains a binder containing at least 1 selected from the group consisting of polyester resins and urethane resins.
In one embodiment, the adhesive contains a urethane resin.
In one embodiment, the topcoat layer contains an antistatic component.
In one embodiment, the Young's modulus of the substrate layer at 23 ℃ is 6.0X 10 7 Pa or above.
In one embodiment, the material of the base material layer is at least 1 selected from the group consisting of polyimide and polyetheretherketone.
In one embodiment, the surface of the base material layer opposite to the surface having the adhesive layer has a top coat layer containing a binder and an antistatic component, the binder contains a urethane resin, and the material of the base material layer is at least 1 selected from the group consisting of polyimide and polyether ether ketone.
In one embodiment, the protective film of the present invention has a bend angle of 60 to 180 degrees after bending at 6 Φ and holding at 90 ℃ for 48 hours, releasing the bend and leaving at 23 ℃ and 50% RH for 24 hours.
In one embodiment, the protective film of the present invention has a total light transmittance of 40% or more.
In one embodiment, the protective film of the present invention has a haze of 10% or less.
In one embodiment, the pressure-sensitive adhesive layer has an adhesive strength of 1N/25mm or more to a glass plate under conditions of 23 ℃, a stretching speed of 300 mm/min, and 180-degree peeling.
In one embodiment, the adhesive layer has a storage modulus at 25 ℃ of 75kPa or less.
In one embodiment, the Tg of the pressure-sensitive adhesive layer is-10 ℃ or lower.
In one embodiment, the adhesive layer includes an acrylic adhesive including an acrylic polymer as a base polymer.
In one embodiment, the acrylic polymer is obtained by polymerizing a monomer component (M) in which R is represented by formula (1) 1 Is a hydrogen atom or a methyl group, R 2 The content ratio of the alkyl (meth) acrylate (m 1) which is a C10-20 chain alkyl group is 5 to 65% by weight.
CH 2 ＝C(R 1 )COOR 2 (1)
In one embodiment, the monomer component (M) contains 2-ethylhexyl acrylate in an amount of 15 to 85 wt%.
In one embodiment, the total content of the alkyl (meth) acrylate (M1) and the 2-ethylhexyl acrylate in the monomer component (M) is 65 to 98% by weight.
In one embodiment, R in the alkyl (meth) acrylate (m 1) is 2 Is a chain alkyl of C10-13.
In one embodiment, the alkyl (meth) acrylate (m 1) is lauryl acrylate.
In one embodiment, the monomer component (M) contains at least 1 selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.
In one embodiment, the protective film of the present invention is attached to a foldable member.
In one embodiment, the foldable member is an OLED.
In one embodiment, the protective film of the present invention is attached to a crimpable member.
In one embodiment, the rollable component is an OLED.
The foldable device according to an embodiment of the present invention includes the above-described protective film.
The rollable device according to an embodiment of the present invention is provided with the above-described protective film.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a protective film having excellent bend recovery properties, excellent transparency, and excellent foreign matter inspection properties can be provided, which does not damage a barrier layer even when bonded to the back side of a polyimide substrate having the barrier layer. According to the invention, a foldable device and a rollable device provided with such a protective film can also be provided.
Drawings
Fig. 1 is a schematic cross-sectional view showing an embodiment of a foldable device of the present invention, and shows one use form of a protective film of the present invention.
Fig. 2 is a schematic cross-sectional view illustrating a method of evaluating the bending recovery property.
Detailed Description
Protective film
Typically, the protective film according to the embodiment of the present invention is a protective film directly bonded to a polyimide substrate. That is, a laminate structure of a polyimide substrate and a protective film ([ polyimide substrate ]/[ protective film ]) is formed in such a manner that the protective film according to the embodiment of the present invention is directly bonded to the polyimide substrate.
As the polyimide substrate, any and appropriate polyimide substrate can be used within a range not impairing the effects of the present invention. A typical example of such a polyimide substrate is a polyimide substrate provided in an OLED.
The protective film according to the embodiment of the present invention is excellent in the bend recovery property, does not damage the barrier layer even when bonded to the back side of the polyimide substrate having the barrier layer, is excellent in the transparency, and is excellent in the foreign substance inspection property, and therefore, is preferably bonded to a foldable member. As the foldable member, any and appropriate member may be used as long as it can be repeatedly bent. Examples of such a foldable member include a foldable optical member and a foldable electronic member, and typically, a foldable OLED. Therefore, typically, the protective film according to the embodiment of the present invention is directly attached to a polyimide substrate provided in a foldable OLED.
The protective film of the present invention is excellent in the bend recovery property, does not damage a barrier layer even when bonded to the back side of a polyimide substrate having the barrier layer, is excellent in transparency, and is excellent in foreign matter inspection property, and therefore, is preferably attached to a crimpable member. As the crimpable member, any and appropriate member may be adopted as long as it can be repeatedly wound and unwound. Examples of such a rollable member include a rollable optical member, a rollable electronic member, and the like, and representatively, a rollable OLED. Therefore, the protective film according to the embodiment of the present invention is typically directly bonded to a polyimide substrate provided in a rollable OLED.
The thickness of the polyimide substrate to which the protective film according to the embodiment of the present invention is directly bonded may be set to any and appropriate thickness according to the purpose of use of the polyimide substrate. From the viewpoint of further exhibiting the effect of the present invention, the thickness is preferably 1 μm to 100. Mu.m, more preferably 3 μm to 50 μm, still more preferably 5 μm to 25 μm, and particularly preferably 10 μm to 20 μm.
When the polyimide substrate to which the protective film according to the embodiment of the present invention is directly bonded is a polyimide substrate used for an OLED, the organic EL layer is easily deteriorated by moisture because moisture is easily contained in the polyimide substrate. Therefore, when the polyimide substrate to which the protective film according to the embodiment of the present invention is directly bonded is a polyimide substrate used for an OLED, it is preferable to provide a barrier layer on a surface of the polyimide substrate opposite to the side to which the protective film is directly bonded. The barrier layer is made of a brittle material such as SiO or SiN, and is very fragile and extremely thin, typically, about 50nm to 300nm in thickness.
The protective film according to the embodiment of the present invention includes a base layer and an adhesive layer. That is, the protective film according to the embodiment of the present invention may have any other layer as long as it has a base layer and an adhesive layer, within a range not impairing the effects of the present invention.
The base material layer may be 1 layer or 2 or more layers. The base material layer is preferably 1 layer from the viewpoint of further exhibiting the effects of the present invention.
The pressure-sensitive adhesive layer may be 1 layer or 2 or more layers. From the viewpoint of further exhibiting the effect of the present invention, the adhesive layer is preferably 1 layer.
The protective film according to the embodiment of the present invention may be provided with an arbitrary and appropriate release liner on the surface of the pressure-sensitive adhesive layer on the side opposite to the base material layer for protection or the like until use.
Examples of the release liner include those obtained by treating the surface of a substrate (liner substrate) such as paper or a plastic film with silicone; and release liners in which a surface of a substrate (liner substrate) such as paper or a plastic film is laminated with a polyolefin resin. Examples of the plastic film as the spacer base include a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, and the like.
The thickness of the release liner is preferably 1 μm to 500. Mu.m, more preferably 3 μm to 450. Mu.m, still more preferably 5 μm to 400. Mu.m, and particularly preferably 10 μm to 300. Mu.m.
One embodiment of the protective film of the present invention includes a laminate of a base material layer and an adhesive layer. Another embodiment of the protective film of the present invention includes a laminate in which a base layer, an adhesive layer, and a release liner are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which a top coat layer, a base material layer, and an adhesive layer are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which a top coat layer, a base material layer, an adhesive layer, and a release liner are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which an antistatic layer, a base layer, and a pressure-sensitive adhesive layer are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which an antistatic layer, a base layer, an adhesive layer, and a release liner are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which a topcoat layer, an antistatic layer, a base layer, and an adhesive layer are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which a topcoat layer, an antistatic layer, a base layer, an adhesive layer, and a release liner are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which an antistatic layer, a top coat layer, a base layer, and an adhesive layer are laminated in this order. Another embodiment of the protective film of the present invention includes a laminate in which an antistatic layer, a top coat layer, a base layer, an adhesive layer, and a release liner are laminated in this order. As for the top coat layer, the antistatic layer, as described later.
The total thickness d of the protective film according to the embodiment of the present invention is preferably 1 μm to 500. Mu.m, more preferably 5 μm to 200. Mu.m, still more preferably 10 μm to 150. Mu.m, particularly preferably 20 μm to 100. Mu.m, and most preferably 30 μm to 80 μm. If the total thickness d of the protective film according to the embodiment of the present invention is within the above range, the effects of the present invention can be further exhibited.
The protective film according to the embodiment of the present invention is preferably bent at 6 Φ and held at 90 ℃ for 48 hours, and then the bend is released and left at 23 ℃ and 50% rh for 24 hours, and then the bent angle is preferably 60 to 180 degrees, more preferably 80 to 180 degrees, still more preferably 100 to 180 degrees, particularly preferably 120 to 180 degrees, and most preferably 150 to 180 degrees. The effect of the present invention can be further exhibited if the bending angle of the protective film according to the embodiment of the present invention after bending at 6 Φ and holding at 90 ℃ for 48 hours, releasing the bending and leaving at 23 ℃ and 50% RH for 24 hours is within the above range.
The bending angle of the protective film according to the embodiment of the present invention, after being bent at 6 Φ and held at 90 ℃ for 48 hours, after releasing the bend and left at 23 ℃ and 50% RH for 24 hours, is an index showing the recovery after bending. The method for measuring the bending angle after bending the sheet at 6. Phi. And holding the sheet at 90 ℃ for 48 hours, releasing the bend and leaving the sheet at 23 ℃ and 50% RH for 24 hours will be described in detail later.
The total light transmittance of the protective film according to the embodiment of the present invention is preferably 40% or more, more preferably 50% or more, further preferably 60% or more, particularly preferably 70% or more, and most preferably 80% or more. If the total light transmittance of the protective film according to the embodiment of the present invention is within the above range, excellent transparency can be further exhibited.
The haze of the protective film according to the embodiment of the present invention is preferably 10% or less, more preferably 8% or less, further preferably 6% or less, particularly preferably 5% or less, and most preferably 4% or less. When the haze of the protective film according to the embodiment of the present invention is in the above range, excellent transparency can be further exhibited.
In the protective film according to the embodiment of the present invention, the surface roughness Ra of the outermost surface on the side opposite to the pressure-sensitive adhesive layer as viewed from the base layer may be any value as long as it is large or small. This means that: in the protective film according to the embodiment of the present invention, the surface roughness Ra may be large even if the substrate layer does not substantially contain particles or aggregates of particles having a feret's diameter of 1 μm or more, or the surface roughness Ra may be small even if the substrate layer contains particles or aggregates of particles having a feret's diameter of 1 μm or more. That is, it means that the surface roughness Ra does not have a correlation with the amount of particles or aggregates of particles having a feret diameter of 1 μm or more in the base material layer.
Substrate layer
The thickness of the substrate layer is preferably 1 to 500. Mu.m, more preferably 5 to 300. Mu.m, still more preferably 10 to 100. Mu.m, particularly preferably 15 to 80 μm, and most preferably 20 to 60 μm. If the thickness of the base material layer is within the above range, the effects of the present invention can be further exhibited.
The Young's modulus of the base material layer at 23 ℃ is preferably 6.0X 10 7 Pa or more, more preferably 1.0X 10 8 Pa or more, and more preferably 5.0X 10 8 Pa or more, particularly preferably 8.0X 10 8 Pa or more, most preferably 1.0X 10 9 Pa or above. Typically, the upper limit of the Young's modulus of the substrate layer at 23 ℃ is preferably 1.0X 10 11 Pa or less. If the Young's modulus of the substrate layer at 23 ℃ is within the above range, the effects of the present invention can be further exhibited. If the young's modulus of the base material layer at 23 ℃ is too low, the protective film may not be able to sufficiently maintain the tension on the outer diameter side against the compression on the inner diameter side when it is bent at an angle, and the thickness may easily change, and lifting from the adherend may easily occur. If the young's modulus of the base material layer at 23 ℃ is too high, the protective film may not be easily deformed. The method for measuring Young's modulus will be described in detail later.
As the material of the base layer, any and appropriate material can be used within a range not impairing the effects of the present invention. As a representative material of such a base layer, a resin material can be cited.
Examples of the resin material as a material of the base layer include acrylic resins such as Polyimide (PI), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polymethyl methacrylate (PMMA); polycarbonate, cellulose Triacetate (TAC), polysulfone, polyarylate, polyethylene (PE), polypropylene (PP), an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyvinyl chloride (PVC), polyvinyl acetate, polyphenylene Sulfide (PPs), a fluorine-based resin, a cyclic olefin-based polymer, and the like.
As the resin material as the material of the base layer, at least 1 selected from the group consisting of Polyimide (PI), polyether ether ketone (PEEK), polyethylene naphthalate (PEN), and a cyclic olefin polymer is preferably used, at least 1 selected from the group consisting of Polyimide (PI), polyether ether ketone (PEEK), and polyethylene naphthalate (PEN) is more preferably used, and at least 1 selected from the group consisting of Polyimide (PI) and polyether ether ketone (PEEK) is even more preferably used, from the viewpoint that the effects of the present invention can be further exhibited.
The base material layer preferably contains substantially no particles or aggregates of particles having a Ferrett diameter of 1 μm or more. As used herein, "substantially free" means: ideally, the substrate layer does not contain particles having a Feret diameter of 1 μm or more (1 particle or none), and actually, the inside of the substrate layer is observed with a digital microscope, for example, and the particles are per unit area (0.02 mm) 2 ) The number of particles having a feret diameter of 1 μm or more observed in (a) is preferably 9 or less, more preferably 5 or less, further preferably 3 or less, and particularly preferably 0.
The term "substantially free" also includes the fact that the substrate layer does not contain "actively added" particles or aggregates of particles having a Ferrett diameter of 1 μm or more, for example, in the substrate layerThe presence of an unintentionally contained trace amount of particles or aggregates of particles having a feret diameter of 1 μm or more, such as when particles or aggregates of particles having a feret diameter of 1 μm or more are mixed as impurities in the production process of (2), may be included in "substantially not contained" as long as the effect of the present invention is not impaired. Of course, in this case, the inside of the base material layer was observed by a digital microscope and observed at a rate of per unit area (0.02 mm) 2 ) The number of particles or aggregates of particles having a feret diameter of 1 μm or more observed in (a) is preferably 9 or less, more preferably 5 or less, further preferably 3 or less, and particularly preferably 0.
The feret diameter is an index of the size of the particles or aggregates of the particles to be targeted, and is also called a constant-direction diameter. The feret diameter is the distance between parallel lines obtained by sandwiching a projected image of the particle with parallel lines in a certain direction, and is the length of the portion where the straight line distance is the longest. The Ferrett diameter can be observed and measured by a digital microscope or the like. The shape of the particles or the aggregates of the particles may be various shapes such as spherical, spheroid, needle-like, various geometric shapes, various irregular shapes, and the like.
The surface resistance value measured on the surface of the base material layer is preferably 10 12 Ω or less, more preferably 10 4 Ω～10 12 Ω, more preferably 10 4 Ω～10 11 Ω, particularly preferably 5X 10 4 Ω～10 10 Omega, most preferably 10 4 Ω～10 9 Omega. The protective film exhibiting such a surface resistance value can be suitably used as a protective film used in processing, transportation, or the like of an article which is not subjected to static electricity, such as a liquid crystal cell, a semiconductor device, or the like. The value of the surface resistance value of the surface of the base material layer can be measured by, for example, a resistivity meter.
Adhesive layer
The thickness of the pressure-sensitive adhesive layer is preferably 1 to 500. Mu.m, more preferably 3 to 300. Mu.m, still more preferably 5 to 100. Mu.m, particularly preferably 7 to 75 μm, and most preferably 10 to 50 μm. If the thickness of the adhesive layer is within the above range, the effects of the present invention can be further exhibited.
The adhesive strength of the pressure-sensitive adhesive layer to a glass plate under conditions of a stretching speed of 300 mm/min at 23 ℃ and 180 degrees peeling is preferably 1N/25mm or more, more preferably 5N/25mm or more, still more preferably 10N/25mm or more, particularly preferably 12N/25mm or more, and most preferably 15N/25mm or more. Typically, the upper limit of the adhesive force of the pressure-sensitive adhesive layer to the glass plate under the conditions of 23 ℃ and a stretching speed of 300 mm/min and 180 degrees peeling is preferably 1000N/25mm or less, more preferably 500N/25mm or less, still more preferably 300N/25mm or less, particularly preferably 200N/25mm or less, and most preferably 100N/25mm or less. The effect of the present invention can be further exhibited if the adhesive force of the adhesive layer to the glass plate under the conditions of 23 ℃, the stretching speed of 300 mm/min, and 180-degree peeling is within the above range.
The storage modulus of the pressure-sensitive adhesive layer at 25 ℃ is preferably 75kPa or less, more preferably 70kPa or less, still more preferably 65kPa or less, particularly preferably 60kPa or less, and most preferably 55kPa or less. The lower limit of the storage modulus at 25 ℃ of the pressure-sensitive adhesive layer is preferably 1kPa or more, more preferably 5kPa or more, still more preferably 10kPa or more, particularly preferably 15kPa or more, and most preferably 20kPa or more. The effects of the present invention can be further exhibited if the storage modulus of the adhesive layer at 25 ℃ is within the above range.
The glass transition temperature Tg of the pressure-sensitive adhesive layer may be, for example, -80 ℃ or higher from the viewpoint that the effects of the present invention can be further exhibited, particularly from the viewpoint that the obtained protective film can exhibit excellent bending durability. The Tg is preferably set to-15 ℃ or less from the viewpoint of improving the deformability of the pressure-sensitive adhesive layer in the shear direction, particularly from the viewpoint of enabling the resulting protective film to exhibit excellent bending durability. In some embodiments, the Tg of the adhesive layer is, for example, preferably 10 ℃ or less, more preferably 0 ℃ or less, even more preferably-10 ℃ or less, even more preferably-15 ℃ or less, particularly preferably-20 ℃ or less, and most preferably-30 ℃ or less. The Tg of the pressure-sensitive adhesive layer is designed so that the Tg is preferably equal to or higher than-80 ℃ (more preferably equal to or higher than-70 ℃, further preferably equal to or higher than-60 ℃, and particularly preferably equal to or higher than-50 ℃) in view of improving the aggregation property and shape recovery property, and particularly in view of enabling the obtained protective film to exhibit excellent bending durability.
The adhesive layer comprises a base polymer. The number of the base polymers may be only 1, or may be 2 or more. From the viewpoint of further exhibiting the effect of the present invention, the content ratio of the base polymer in the pressure-sensitive adhesive layer is preferably 20 to 100% by weight, more preferably 30 to 95% by weight, still more preferably 40 to 90% by weight, particularly preferably 45 to 85% by weight, and most preferably 50 to 80% by weight.
As the base polymer, any and appropriate polymer may be used within a range not impairing the effects of the present invention. From the viewpoint of further exhibiting the effects of the present invention, the base polymer is preferably at least 1 selected from the group consisting of acrylic polymers, rubber polymers, silicone polymers, and urethane polymers. That is, the adhesive layer preferably contains at least 1 kind selected from the following adhesives: an acrylic adhesive containing an acrylic polymer, a rubber adhesive containing a rubber polymer, a silicone adhesive containing a silicone polymer, a urethane adhesive containing a urethane polymer. The pressure-sensitive adhesive layer preferably contains an acrylic pressure-sensitive adhesive from the viewpoint that the effects of the present invention can be further exhibited. That is, the adhesive layer contains an acrylic adhesive containing an acrylic polymer as a base polymer, from the viewpoint that the effects of the present invention can be further exhibited.
Hereinafter, acrylic adhesives will be described in detail as representative examples of the adhesives that can be contained in the adhesive layer.
< acrylic pressure-sensitive adhesive >
The acrylic adhesive contains an acrylic polymer as a base polymer. The acrylic adhesive optionally comprises an oligomer. The acrylic adhesive optionally comprises a tackifying resin. The acrylic adhesive optionally comprises a crosslinking agent.
When the acrylic adhesive contains an acrylic polymer, a tackifier resin, and a crosslinking agent, the content ratio of the total amount of the acrylic polymer, the tackifier resin, and the crosslinking agent to the total amount of the acrylic adhesive is preferably 95% by weight or more, more preferably 97% by weight or more, and still more preferably 99% by weight or more, from the viewpoint of further exhibiting the effects of the present invention.
(acrylic acid Polymer)
The acrylic polymer is preferably a polymer of a monomer component (M) containing, for example, an alkyl (meth) acrylate as a main monomer and further containing a secondary monomer having copolymerizability with the main monomer. Here, the main monomer means a component occupying more than 50% by weight of the whole monomer component (M).
As described above, the acrylic polymer can be defined as a polymer obtained by polymerizing the monomer component (M). On the other hand, since the acrylic polymer is an acrylic polymer obtained by polymerizing the monomer component (M), the acrylic polymer cannot be directly specified depending on the structure thereof, and there is a case where it is not practical ("impossible/impractical"), the acrylic polymer can be properly specified as "product" by the definition of "obtained by polymerizing the monomer component (M)".
As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be suitably used.
CH 2 ＝C(R 1 )COOR 2 (1)
Here, R in the above formula (1) 1 Is a hydrogen atom or a methyl group, R 2 Is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of carbon atoms is sometimes referred to as "C1-20"). R is R from the viewpoint of storage modulus of the pressure-sensitive adhesive layer or the like 2 The alkyl group is preferably a C1-14 chain alkyl group, more preferably a C2-13 chain alkyl group, and still more preferably a C4-12 chain alkyl group. Here, the chain means a meaning including a straight chain and a branched chain.
As R 2 Examples of the alkyl (meth) acrylate that is a chain alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate. These alkyl (meth) acrylates may be used in only 1 kind, or may be used in 2 or more kinds.
The alkyl (meth) acrylate preferably includes n-Butyl Acrylate (BA), 2-ethylhexyl acrylate (2 EHA), and lauryl (meth) acrylate, from the viewpoint of further exhibiting the effects of the present invention.
As for the alkyl (meth) acrylate, since a homopolymer of the alkyl (meth) acrylate having a long-chain alkyl group of C10 or more has a temperature region (plateau region) in which the temperature dependence of viscoelasticity is small at a temperature higher than Tg, the temperature dependence of tan δ tends to be small when used as the monomer component (M). From this viewpoint, in one embodiment of the present invention, it is preferable that an alkyl (meth) acrylate having a C10-16 long-chain alkyl group is used as the alkyl (meth) acrylate, more preferably an alkyl (meth) acrylate having a C10-13 long-chain alkyl group is used as the alkyl (meth) acrylate, and particularly preferably lauryl (meth) acrylate having an alkyl (meth) acrylate having a C12 long-chain alkyl group is used as the alkyl (meth) acrylate.
From the viewpoint of further exhibiting the effect of the present invention, the content ratio of the alkyl (meth) acrylate in the total monomer components (M) used for the synthesis of the acrylic polymer is preferably 70% by weight or more, more preferably 85% by weight or more, and still more preferably 90% by weight or more. The upper limit of the content of the alkyl (meth) acrylate is preferably 99.5% by weight or less, and more preferably 99% by weight or less. However, the acrylic polymer may be obtained by polymerizing substantially only alkyl (meth) acrylate.
As an embodiment of the acrylic polymer, in the monomer component (M), R is represented by the formula (1) 1 Is a hydrogen atom or a methyl group, R 2 The content ratio of the alkyl (meth) acrylate (m 1) which is a chain alkyl group having 10 to 20 carbon atoms is preferably 5 to 65% by weight, more preferably 6 to 65% by weight, and still more preferably 7 to 65% by weight. If the content ratio of the alkyl (meth) acrylate (M1) in the monomer component (M) is within the above range, the effects of the present invention can be further exhibited. In particular, the resulting protective film can exhibit excellent bending durability.
In the formula (1) and R 1 Is a hydrogen atom or a methyl group, R 2 In the alkyl (meth) acrylate (m 1) having a C10-20 chain alkyl group, R is a group represented by formula (I) in order to further exhibit the effect of the present invention 2 Preferably a C10-14 chain alkyl group, more preferably a C10-13 chain alkyl group, still more preferably a C10-13 chain alkyl group, particularly preferably a C12 chain alkyl group, and most preferably lauryl acrylate.
In one embodiment of the acrylic polymer, the content of 2-ethylhexyl acrylate in the monomer component (M) is preferably 15 to 85 wt%, more preferably 17 to 83 wt%, still more preferably 20 to 80 wt%, and particularly preferably 20 to 75 wt%. If the content ratio of 2-ethylhexyl acrylate in the monomer component (M) is within the above range, the effects of the present invention can be further exhibited. In particular, the resulting protective film can exhibit excellent bending durability.
In one embodiment of the acrylic polymer, the content of 2-ethylhexyl acrylate in the monomer component (M) may be more than 85% by weight and 98% by weight or less. In this embodiment, the content of the alkyl (meth) acrylate (M1) in the monomer component (M) is preferably less than 5% by weight, more preferably less than 3% by weight, still more preferably less than 1% by weight, particularly preferably less than 0.1% by weight, and most preferably substantially 0% by weight.
In one embodiment of the acrylic polymer, the total content of the alkyl (meth) acrylate (M1) and 2-ethylhexyl acrylate in the monomer component (M) is preferably 65 to 98 wt%, more preferably 70 to 95 wt%, still more preferably 72 to 93 wt%, and particularly preferably 75 to 90 wt%. If the total content ratio of the alkyl (meth) acrylate (M1) and 2-ethylhexyl acrylate in the monomer component (M) is within the above range, the effects of the present invention can be further exhibited. In particular, the resulting protective film can exhibit excellent bending durability.
In one embodiment of the acrylic polymer, when the monomer component (M) contains an alkyl (meth) acrylate (M1) and 2-ethylhexyl acrylate, the weight ratio of 2-ethylhexyl acrylate to 100 parts by weight of the alkyl (meth) acrylate (M1) is preferably 10 to 1000 parts by weight, more preferably 20 to 950 parts by weight, particularly preferably 30 to 900 parts by weight, and most preferably 30 to 880 parts by weight. The effects of the present invention can be further exhibited if the weight ratio of 2-ethylhexyl acrylate to 100 parts by weight of the alkyl (meth) acrylate (m 1) is within the above range. In particular, the resulting protective film can exhibit excellent bending durability.
As an embodiment of the acrylic polymer, the monomer component (M) may contain R represented by the formula (1) 1 Is a hydrogen atom or a methyl group, R 2 And (m 2) an alkyl (meth) acrylate having a C4-7 chain alkyl group. In one embodiment of the acrylic polymer, the content of the alkyl (meth) acrylate (M2) in the monomer component (M) may be 50% by weight or more, preferably less than 50% by weight, more preferably 40% by weight or less,more preferably 35% by weight or less, particularly preferably 30% by weight or less, and most preferably 25% by weight or less. If the content ratio of the alkyl (meth) acrylate (M2) in the monomer component (M) is within the above range, the effects of the present invention can be further exhibited.
As represented by formula (1) and R 1 Is a hydrogen atom or a methyl group, R 2 The alkyl (meth) acrylate (m 2) which is a chain alkyl group of C4-7 is preferably n-Butyl Acrylate (BA).
One embodiment of the acrylic polymer includes an acrylic polymer in which n-Butyl Acrylate (BA) accounts for less than 50 wt% of the total monomer components (M). In this case, the content ratio of n-Butyl Acrylate (BA) in the entire monomer component (M) is preferably more than 0% by weight and 48% by weight or less, more preferably 5% by weight to 45% by weight, still more preferably 10% by weight to 43% by weight, particularly preferably 15% by weight to 40% by weight, and most preferably 20% by weight to 35% by weight, from the viewpoint of further exhibiting the effects of the present invention. The entire monomer component (M) may further contain 2-ethylhexyl acrylate (2 EHA) in a proportion greater than n-Butyl Acrylate (BA).
One embodiment of the acrylic polymer includes an acrylic polymer in which n-Butyl Acrylate (BA) accounts for 50 wt% or more of the total monomer components (M). In this case, the content ratio of n-Butyl Acrylate (BA) in the entire monomer component (M) is preferably more than 50% by weight and 100% by weight or less, more preferably 55% by weight to 95% by weight, still more preferably 60% by weight to 90% by weight, particularly preferably 63% by weight to 85% by weight, and most preferably 65% by weight to 80% by weight, from the viewpoint of further exhibiting the effects of the present invention. The entire monomer component (M) may further contain 2-ethylhexyl acrylate (2 EHA) in a smaller proportion than n-Butyl Acrylate (BA).
As an embodiment of the acrylic polymer, there may be mentioned an acrylic polymer in which less than 50% by weight of the total monomer component (M) is 2-ethylhexyl acrylate (2 EHA). In this case, from the viewpoint of further exhibiting the effect of the present invention, the content ratio of 2-ethylhexyl acrylate (2 EHA) in the entire monomer component (M) is preferably more than 0% by weight and 48% by weight or less, more preferably 5% by weight to 45% by weight, still more preferably 10% by weight to 43% by weight, particularly preferably 15% by weight to 40% by weight, and most preferably 20% by weight to 35% by weight. The entire monomer component (M) may further contain n-Butyl Acrylate (BA) in a larger proportion than 2-ethylhexyl acrylate (2 EHA).
One embodiment of the acrylic polymer includes an acrylic polymer in which at least 50% by weight of the total monomer component (M) is 2-ethylhexyl acrylate (2 EHA). In this case, from the viewpoint of further exhibiting the effect of the present invention, the content ratio of 2-ethylhexyl acrylate (2 EHA) in the entire monomer component (M) is preferably more than 50% by weight and 100% by weight or less, more preferably 55% by weight to 98% by weight, still more preferably 60% by weight to 90% by weight, particularly preferably 63% by weight to 85% by weight, and most preferably 65% by weight to 80% by weight. The entire monomer component (M) may further contain n-Butyl Acrylate (BA) in a smaller proportion than 2-ethylhexyl acrylate (2 EHA).
In the acrylic polymer, other monomers may be copolymerized within a range not impairing the effects of the present invention. The other monomer may be used for the purpose of, for example, introducing a functional group capable of becoming a crosslinking group site into the acrylic polymer, improving the adhesive strength, adjusting the glass transition temperature (Tg) of the acrylic polymer, adjusting the adhesive properties, and the like.
Examples of the other monomer that can introduce a functional group that can serve as a crosslinking group site into the acrylic polymer or contribute to improvement of the adhesive strength include a hydroxyl group (OH group) -containing monomer, a carboxyl group-containing monomer, an acid anhydride group-containing monomer, a nitrogen-containing monomer (e.g., an amide group-containing monomer, an amino group-containing monomer, and an imide group-containing monomer), an epoxy group-containing monomer, (meth) acryloyl morpholine, and vinyl ethers.
Examples of the other monomer capable of improving the cohesive force and heat resistance of the adhesive include a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, a vinyl ester, an aromatic vinyl compound, and the like, and a vinyl ester is preferable. Specific examples of the vinyl ester include vinyl acetate (VAc), vinyl propionate, and vinyl laurate, and vinyl acetate (VAc) is preferable.
The other monomer is preferably at least 1 selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer, from the viewpoint of further exhibiting the effects of the present invention.
The "other monomer" may be only 1 kind or 2 or more kinds. The content of the other monomer in the entire monomer component (M) is preferably 0.001 to 40% by weight, more preferably 0.01 to 40% by weight, still more preferably 0.1 to 10% by weight, particularly preferably 0.5 to 5% by weight, and most preferably 1 to 3% by weight.
As an embodiment of the acrylic polymer, there can be mentioned an acrylic polymer obtained by copolymerizing a carboxyl group-containing monomer as another monomer. Examples of the carboxyl group-containing monomer include Acrylic Acid (AA), methacrylic acid (MAA), carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Among these, acrylic Acid (AA) and methacrylic acid (MAA) are preferable, and Acrylic Acid (AA) is more preferable, from the viewpoint of further exhibiting the effect of the present invention.
When a carboxyl group-containing monomer is used as the other monomer, the content of the carboxyl group-containing monomer in the entire monomer component (M) is preferably 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, even more preferably 0.5 to 5% by weight, particularly preferably 0.7 to 4% by weight, and most preferably 1 to 3% by weight, from the viewpoint of further exhibiting the effect of the present invention.
As an embodiment of the acrylic polymer, there can be mentioned an acrylic polymer obtained by copolymerizing a hydroxyl group-containing monomer as another monomer. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; polypropylene glycol mono (meth) acrylate; n-hydroxyethyl (meth) acrylamide, and the like. Among these, as the hydroxyl group-containing monomer, from the viewpoint of further exhibiting the effect of the present invention, a linear hydroxyalkyl (meth) acrylate in which the alkyl group has 2 to 4 carbon atoms is preferable, and specifically, for example, 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4 HBA) are preferable, and 4-hydroxybutyl acrylate (4 HBA) is more preferable.
When a hydroxyl group-containing monomer is used as the other monomer, the content of the hydroxyl group-containing monomer in the entire monomer component (M) is preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, even more preferably 0.02 to 2% by weight, particularly preferably 0.03 to 1% by weight, and most preferably 0.05 to 0.5% by weight, from the viewpoint of further exhibiting the effects of the present invention.
As one embodiment of the acrylic polymer, there can be mentioned an acrylic polymer obtained by copolymerizing a nitrogen-containing monomer as another monomer. Examples of the nitrogen-containing monomer include nitrogen-containing vinyl monomers such as N-vinyl-2-pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, (meth) acryloyl morpholine, N-vinyl carboxylic acid amides, and N-vinyl caprolactam; cyano group-containing acrylic monomers such as acrylonitrile and methacrylonitrile; and the like. Among these, N-vinyl-2-pyrrolidone is preferably used as the nitrogen-containing monomer, from the viewpoint of further exhibiting the effects of the present invention.
When a nitrogen-containing monomer is used as the other monomer, the content of the nitrogen-containing monomer in the entire monomer component (M) is preferably 0.1 to 50% by weight, more preferably 0.2 to 30% by weight, even more preferably 0.3 to 20% by weight, particularly preferably 0.4 to 15% by weight, and most preferably 0.5 to 15% by weight, from the viewpoint of further exhibiting the effect of the present invention.
The Tg of the base polymer may be, for example, -80 ℃ or higher from the viewpoint that the effects of the present invention can be further exhibited, particularly from the viewpoint that the resulting protective film can exhibit excellent bending durability. The base polymer (preferably an acrylic polymer) is designed so that Tg is preferably-15 ℃ or less from the viewpoint of improving the deformability of the pressure-sensitive adhesive layer with respect to the shear direction, particularly from the viewpoint that the obtained protective film can exhibit excellent bending durability. In some embodiments, the Tg of the base polymer is, for example, preferably-10 ℃ or less, more preferably-15 ℃ or less, even more preferably-20 ℃ or less, even more preferably-25 ℃ or less, particularly preferably-40 ℃ or less, and most preferably-50 ℃ or less. The Tg of the base polymer is designed so that, for example, the Tg is preferably-70 ℃ or higher (more preferably-65 ℃ or higher, and still more preferably-60 ℃ or higher) from the viewpoint of improving the aggregability and shape recovery, and particularly from the viewpoint of enabling the obtained protective film to exhibit excellent bending durability.
The Tg of the base polymer means: the value obtained by the Fox equation is based on the Tg of the homopolymer (homopolymer) of each monomer constituting the base polymer and the weight fraction (copolymerization ratio on the weight basis) of the monomer. The Fox formula refers to: as shown below, the relationship between Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1/Tg＝Σ(Wi/Tgi)
In the above Fox formula, tg represents the glass transition temperature (unit: K) of the copolymer, wi represents the weight fraction (copolymerization ratio on a weight basis) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i. The Tg of the homopolymer is as described in the literature.
As the Tg of the homopolymer, for example, the following values can be specifically used.
Figure BDA0003403850940000201
With respect to the Tg of the homopolymer other than those exemplified above, the numerical values described in "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989) can be used. When a plurality of numerical values are described in the "Polymer Handbook", the numerical values used are conventional values. As for the monomer not described in the above-mentioned "Polymer Handbook", the catalog value of the monomer manufacturing company was used. The Tg of a homopolymer of a monomer which is not described in the above-mentioned "Polymer Handbook" or which does not provide a catalogue value for a monomer manufacturing company is a value obtained by a measurement method described in Japanese patent laid-open No. 2007-51271.
As a method for obtaining the acrylic polymer, various polymerization methods known as a method for synthesizing an acrylic polymer such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method can be suitably used. Among these polymerization methods, the solution polymerization method can be preferably used. As a method of supplying the monomer in the solution polymerization, a batch feeding method, a continuous supply (dropping) method, a divided supply (dropping) method, and the like, in which the whole amount of the monomer component is supplied in batch, can be suitably employed. The polymerization temperature may be appropriately selected depending on the kind of the monomer and the solvent used, the kind of the polymerization initiator, and the like, and is preferably 20 ℃ or more, more preferably 30 ℃ or more, further preferably 40 ℃ or more, and is preferably 170 ℃ or less, more preferably 160 ℃ or less, further preferably 140 ℃ or less. As a method for obtaining an acrylic polymer, photopolymerization by irradiation with light such as UV (typically, in the presence of a photopolymerization initiator) can be employed; radiation polymerization by irradiation with an active energy ray such as radiation polymerization by irradiation with a radiation ray such as β -ray or γ -ray.
The solvent (polymerization solvent) used for the solution polymerization may be appropriately selected from any and appropriate organic solvents. Examples thereof include aromatic compounds (typically, aromatic hydrocarbons) such as toluene; acetic acid esters such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane.
The initiator (polymerization initiator) used for the polymerization can be appropriately selected from arbitrary and appropriate polymerization initiators according to the kind of the polymerization method. The number of polymerization initiators may be 1 or 2 or more. Examples of such a polymerization initiator include azo polymerization initiators such as 2,2' -Azobisisobutyronitrile (AIBN); persulfates such as potassium persulfate; peroxide initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; an aromatic carbonyl compound; and the like. As another example of the polymerization initiator, a redox-type initiator based on a combination of a peroxide and a reducing agent can be cited.
The amount of the polymerization initiator to be used is preferably 0.005 to 1 part by weight, more preferably 0.01 to 1 part by weight, based on 100 parts by weight of the total monomer components.
The Mw of the acrylic polymer is preferably 10X 10 4 ～500×10 4 More preferably 10X 10 4 ～150×10 4 More preferably 20X 10 4 ～75×10 4 Particularly preferably 35X 10 4 ～65×10 4 . Here, mw is a value in terms of standard polystyrene obtained by GPC (gel permeation chromatography). As the GPC apparatus, for example, the type name "HLC-8320GPC" (column: TSKgel GMH-H (S), manufactured by Tosoh corporation) can be used.
(oligomer)
The acrylic adhesive may comprise an oligomer. The number of oligomers may be only 1, or may be 2 or more. The acrylic adhesive can further exhibit the effects of the present invention by including an oligomer. In particular, the resulting protective film can exhibit excellent bending durability.
The weight average molecular weight Mw of the oligomer is preferably 1000 to 30000, more preferably 1500 to 10000, still more preferably 2000 to 8000, and particularly preferably 2000 to 5000. By using such an oligomer having a weight average molecular weight Mw, the adhesiveness and elasticity of the acrylic adhesive sheet can be improved.
The oligomer is preferably an acrylic oligomer, from the viewpoint of being easily compatible with an acrylic polymer.
The glass transition temperature Tg of the acrylic oligomer is preferably 20 ℃ or higher, more preferably 40 ℃ or higher, still more preferably 60 ℃ or higher, particularly preferably 80 ℃ or higher, and most preferably 100 ℃ or higher. The upper limit of the glass transition temperature Tg of the acrylic oligomer is preferably 200 ℃ or lower, more preferably 180 ℃ or lower, and still more preferably 160 ℃ or lower.
The glass transition temperature Tg of the acrylic oligomer means: the value obtained from the Fox equation is determined from the Tg of the homopolymer (homo polymer) of each of the constituent monomers and the weight fraction (copolymerization ratio based on the weight) of the monomer. The Fox formula refers to: as shown below, the relationship between Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each monomer constituting the copolymer.
1/Tg＝Σ(Wi/Tgi)
In the above Fox equation, tg represents the glass transition temperature (unit: K) of a copolymer, wi represents the weight fraction (weight-based copolymerization ratio) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of a homopolymer of the monomer i. The Tg of the homopolymer can be determined by a value described in publicly known materials, and for example, a value described in "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989) can be used. When a plurality of numerical values are described in the above "Polymer Handbook", the value of conditional is used. As for the monomer not described in the above-mentioned "Polymer Handbook", the catalog value of the monomer manufacturing company was used. The Tg of a homopolymer of a monomer which is not described in the above-mentioned "Polymer Handbook" or which does not provide a catalogue value for a monomer manufacturing company is a value obtained by a measurement method described in Japanese patent laid-open No. 2007-51271.
The acrylic oligomer contains an alicyclic alkyl (meth) acrylate as a main constituent monomer component. The number of the alicyclic alkyl (meth) acrylates may be only 1, or may be 2 or more.
Examples of the alicyclic alkyl (meth) acrylate include cycloalkyl (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate; a (meth) acrylate having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth) acrylate; (meth) acrylic esters having an aliphatic hydrocarbon ring having at least three rings, such as dicyclopentyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, tricyclopentyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate.
The alicyclic alkyl (meth) acrylate is preferably dicyclopentyl acrylate, dicyclopentyl methacrylate, cyclohexyl acrylate, or cyclohexyl methacrylate, from the viewpoint of further exhibiting the effects of the present invention.
From the viewpoint of further exhibiting the effects of the present invention, the content ratio of the alicyclic alkyl (meth) acrylate to the total amount of the constituent monomer components of the acrylic oligomer is preferably 10 to 99% by weight, more preferably 30 to 98% by weight, still more preferably 40 to 97% by weight, and particularly preferably 50 to 96% by weight.
In the acrylic oligomer, as a constituent monomer component, a chain alkyl (meth) acrylate having a chain alkyl group may be contained. The number of the chain alkyl (meth) acrylates having a chain alkyl group may be only 1, or may be 2 or more. Here, the chain means a meaning including a straight chain and a branched chain.
The chain alkyl (meth) acrylate is preferably a chain alkyl (meth) acrylate having a chain alkyl group having 1 to 20 carbon atoms, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate.
The (meth) acrylic acid chain alkyl ester is preferably methyl methacrylate from the viewpoint of further exhibiting the effects of the present invention.
From the viewpoint of further exhibiting the effects of the present invention, the content ratio of the chain alkyl (meth) acrylate to the total amount of the constituent monomer components of the acrylic oligomer is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, and even more preferably 30 to 70% by weight.
The acrylic oligomer may contain (meth) acrylic acid as a constituent monomer component. The number of (meth) acrylic acids may be 1 or 2 or more.
As the (meth) acrylic acid, acrylic acid is preferable from the viewpoint that the effect of the present invention can be further exhibited.
From the viewpoint of further exhibiting the effect of the present invention, the content ratio of (meth) acrylic acid to the total amount of the constituent monomer components of the acrylic oligomer is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight, and still more preferably 3 to 7% by weight.
The oligomer can be obtained by polymerizing constituent monomer components by various polymerization methods. In the polymerization of the oligomer, any and appropriate additive may be used within a range not impairing the effects of the present invention. Examples of such additives include a polymerization initiator and a chain transfer agent.
From the viewpoint of further exhibiting the effect of the present invention, the content ratio of the oligomer in the acrylic pressure-sensitive adhesive is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 8.0 parts by weight, still more preferably 1.0 to 7.0 parts by weight, and particularly preferably 1.5 to 6.0 parts by weight, based on 100 parts by weight of the acrylic polymer.
(tackifying resin)
The acrylic adhesive may contain a tackifier resin from the viewpoint of further exhibiting the effects of the present invention. Examples of the tackifier resin include rosin-based tackifier resins, terpene-based tackifier resins, hydrocarbon-based tackifier resins, epoxy-based tackifier resins, polyamide-based tackifier resins, elastic-based tackifier resins, phenol-based tackifier resins, and ketone-based tackifier resins. The number of the tackifier resins may be only 1, or may be 2 or more.
From the viewpoint of further exhibiting the effect of the present invention, the amount of the tackifier resin to be used is preferably 5 to 70 parts by weight, more preferably 10 to 60 parts by weight, further preferably 15 to 50 parts by weight, further preferably 20 to 45 parts by weight, particularly preferably 25 to 40 parts by weight, and most preferably 25 to 35 parts by weight, based on 100 parts by weight of the base polymer.
From the viewpoint of further exhibiting the effects of the present invention, the tackifier resin preferably contains a tackifier resin TL having a softening point of less than 105 ℃. The tackifying resin TL can effectively contribute to improving the deformability of the adhesive layer to deform in the in-plane direction (shear direction). The softening point of the tackifier resin used as the tackifier resin TL is preferably 50 to 103 ℃, more preferably 60 to 100 ℃, still more preferably 65 to 95 ℃, particularly preferably 70 to 90 ℃, and most preferably 75 to 85 ℃ from the viewpoint of obtaining a higher effect of improving the deformability.
The softening point of a tackifier resin is defined as a value measured according to a softening point test method (ring and ball method) prescribed in JIS K5902 and JIS K2207. Specifically, the sample was melted as quickly as possible at a low temperature, and the sample was filled into a ring placed on a flat metal plate, taking care not to cause bubbling. After cooling, the portion raised from the plane including the upper end of the ring was cut with a slightly heated knife. Next, a holder (ring stand) was placed in a glass container (heating bath) having a diameter of 85mm or more and a height of 127mm or more, and glycerin was injected until the depth reached 90mm or more. Next, a steel ball (diameter 9.5mm, weight 3.5 g) and the ring filled with the sample were immersed in glycerin without contacting each other, and the temperature of the glycerin was maintained at 20 ℃. + -. 5 ℃ for 15 minutes. Next, a steel ball is placed in the center of the sample surface in the ring, and the ring is placed at a fixed position on the holder. Then, the distance from the upper end of the ring to the glycerin surface was kept at 50mm, and the thermometer was placed so that the center position of the mercury bulb of the thermometer was at the same height as the center of the ring, and the container was heated. The flame of the gas torch used for heating is positioned in the middle of the center and the edge of the bottom of the container, and the flame is heated equally. The rate of increase in bath temperature from the start of heating to 40 ℃ must be 5.0. + -. 0.5 ℃ per minute. The sample gradually softens and runs off the ring, and the temperature at which it eventually comes into contact with the base plate is read as the softening point. The softening points were measured 2 or more at the same time, and the average value was used.
The amount of the tackifier resin TL used is preferably 5 to 50 parts by weight, more preferably 10 to 45 parts by weight, still more preferably 15 to 40 parts by weight, particularly preferably 20 to 35 parts by weight, and most preferably 25 to 32 parts by weight, based on 100 parts by weight of the base polymer, from the viewpoint of further exhibiting the effects of the present invention.
As the tackifier resin TL, 1 or 2 or more species selected appropriately from the above exemplified tackifier resins can be used. The tackifier resin TL preferably contains a rosin-based resin.
Examples of the rosin-based resin that can be preferably used as the tackifier resin TL include rosin esters such as unmodified rosin esters and modified rosin esters. Examples of the modified rosin ester include hydrogenated rosin esters.
From the viewpoint of further exhibiting the effects of the present invention, the tackifier resin TL preferably contains a hydrogenated rosin ester. The hydrogenated rosin ester has a softening point of preferably less than 105 ℃, more preferably 50 to 100 ℃, still more preferably 60 to 90 ℃, particularly preferably 70 to 85 ℃, and most preferably 75 to 85 ℃ from the viewpoint of further exhibiting the effects of the present invention.
The tackifying resin TL may comprise a non-hydrogenated rosin ester. Here, the non-hydrogenated rosin ester means: the concept of the rosin esters other than hydrogenated rosin esters is collectively shown. Examples of the non-hydrogenated rosin ester include an unmodified rosin ester, a disproportionated rosin ester, and a polymerized rosin ester.
The non-hydrogenated rosin ester has a softening point of preferably less than 105 ℃, more preferably 50 to 100 ℃, still more preferably 60 to 90 ℃, particularly preferably 70 to 85 ℃, and most preferably 75 to 85 ℃ from the viewpoint of further exhibiting the effects of the present invention.
The tackifier resin TL may contain another tackifier resin in addition to the rosin-based resin. As the other tackifier resins, 1 or 2 or more kinds selected as appropriate from the above-exemplified tackifier resins having a softening point of less than 105 ℃ can be used. The tackifying resin TL may comprise, for example, rosin-based resins and terpene resins.
From the viewpoint of further exhibiting the effect of the present invention, the content of the rosin-based resin in the entire tackifier resin TL is preferably more than 50% by weight, more preferably 55% by weight to 100% by weight, even more preferably 60% by weight to 99% by weight, particularly preferably 65% by weight to 97% by weight, and most preferably 75% by weight to 97% by weight.
The tackifier resin may be a combination of a tackifier resin TL and a tackifier resin TH having a softening point of 105 ℃ or higher (preferably 105 to 170 ℃), from the viewpoint of further exhibiting the effects of the present invention.
As the tackifier resin TH, 1 or 2 or more kinds selected as appropriate from those having a softening point of 105 ℃ or higher can be used among the above exemplified tackifier resins. The tackifying resin TH may comprise at least 1 selected from rosin-based tackifying resins (e.g., rosin esters) and terpene-based tackifying resins (e.g., terpene phenolic resins).
(crosslinking agent)
The acrylic adhesive may contain a crosslinking agent. The number of the crosslinking agents may be only 1, or may be 2 or more. By using the crosslinking agent, an appropriate cohesive force can be imparted to the acrylic pressure-sensitive adhesive. The cross-linking agent also helps to adjust the offset and return distances in the retention test. The acrylic adhesive containing a crosslinking agent can be obtained by, for example, forming an adhesive layer using an adhesive composition containing the crosslinking agent. The crosslinking agent may be contained in the acrylic adhesive in a form after the crosslinking reaction, a form before the crosslinking reaction, a form in which the crosslinking reaction partially occurs, an intermediate form or a composite form thereof, or the like. Typically, the crosslinking agent is mainly contained in the acrylic adhesive in a form after the crosslinking reaction.
From the viewpoint of further exhibiting the effect of the present invention, the amount of the crosslinking agent to be used is preferably 0.005 to 10 parts by weight, more preferably 0.008 to 8 parts by weight, further preferably 0.01 to 7 parts by weight, further preferably 0.01 to 5 parts by weight, further preferably 0.01 to 4 parts by weight, particularly preferably 0.01 to 3 parts by weight, and most preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the base polymer.
Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, metal chelate crosslinking agents, peroxides, crosslinking agents such as polyfunctional monomers, and the like, and from the viewpoint of further exhibiting the effects of the present invention, isocyanate crosslinking agents, epoxy crosslinking agents, peroxides, and polyfunctional monomers are preferable, and isocyanate crosslinking agents, peroxides, and polyfunctional monomers are more preferable.
As the isocyanate-based crosslinking agent, a compound having 2 or more isocyanate groups (including an isocyanate-regenerable functional group in which an isocyanate group is temporarily protected by a blocking agent, multimerization, or the like) in 1 molecule can be used. Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate, and the like.
More specifically, the isocyanate-based crosslinking agent includes, for example, lower aliphatic polyisocyanates such as 1,4-tetramethylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; 2,4 aromatic diisocyanates such as tolylene diisocyanate, 4,4' -diphenylmethane diisocyanate, xylylene diisocyanate, polymethylene polyphenyl isocyanate, etc.; isocyanate adducts such as trimethylolpropane/tolylene diisocyanate trimer adduct (for example, product name: CORONATE L manufactured by Tosoh corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (for example, product name: CORONATE HL manufactured by Tosoh corporation), and isocyanurate of hexamethylene diisocyanate (for example, product name: CORONATE HX manufactured by Tosoh corporation); trimethylolpropane adduct of xylylenediisocyanate (for example, product name: TAKENATE D N manufactured by Mitsui chemical Co., ltd.), trimethylolpropane adduct of xylylenediisocyanate (for example, product name: 3252 zxft 32120N manufactured by Mitsui chemical Co., ltd.), trimethylolpropane adduct of isophorone diisocyanate (for example, product name: TAKENATE D N manufactured by Mitsui chemical Co., ltd.), and trimethylolpropane adduct of hexamethylene diisocyanate (for example, product name: TAKENATE D N manufactured by Mitsui chemical Co., ltd.); polyether polyisocyanates, polyester polyisocyanates, and their adducts with various polyols; and polyisocyanates which are polyfunctional with an isocyanurate bond, a biuret bond, an allophanate bond, or the like. Among these, aromatic isocyanates and alicyclic isocyanates are preferable from the viewpoint of satisfying both deformability and cohesive force in a good balance.
From the viewpoint of further exhibiting the effects of the present invention, the amount of the isocyanate-based crosslinking agent to be used is preferably 0.005 to 10 parts by weight, more preferably 0.008 to 8 parts by weight, still more preferably 0.01 to 7 parts by weight, yet more preferably 0.01 to 5 parts by weight, yet more preferably 0.01 to 4 parts by weight, particularly preferably 0.01 to 3 parts by weight, and most preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the base polymer.
When the monomer component constituting the acrylic polymer contains a hydroxyl group-containing monomer, the weight ratio of the isocyanate-based crosslinking agent/the hydroxyl group-containing monomer is preferably more than 20 and less than 50, more preferably 22 to 45, still more preferably 25 to 40, particularly preferably 27 to 40, and most preferably 30 to 35, from the viewpoint of further exhibiting the effect of the present invention.
When the acrylic adhesive contains the tackifier resin TL having a softening point of 105 ℃ or lower, the weight ratio of the tackifier resin TL/isocyanate-based crosslinking agent is preferably more than 2 and less than 15, more preferably 5 to 13, even more preferably 7 to 12, and particularly preferably 7 to 11, from the viewpoint of further exhibiting the effects of the present invention.
As the epoxy-based crosslinking agent, a polyfunctional epoxy compound having 2 or more epoxy groups in 1 molecule can be used. Examples of the epoxy-based crosslinking agent include N, N' -tetraglycidyl m-xylylenediamine, diglycidylaniline, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, triglycidyl tris (2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol S-diglycidyl ether, and epoxy-based resins having 2 or more epoxy groups in the molecule. Examples of commercially available products of the epoxy-based crosslinking agent include trade names "TETRAD C" and "TETRAD X" manufactured by mitsubishi gas chemical corporation.
From the viewpoint of further exhibiting the effect of the present invention, the amount of the epoxy crosslinking agent to be used is preferably 0.005 to 10 parts by weight, more preferably 0.008 to 8 parts by weight, further preferably 0.01 to 7 parts by weight, further preferably 0.01 to 5 parts by weight, further preferably 0.01 to 4 parts by weight, particularly preferably 0.01 to 3 parts by weight, and most preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the base polymer.
Examples of the polyfunctional monomer include difunctional monomers such as 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, and divinylbenzene; trifunctional or higher polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate; and epoxy acrylates, polyester acrylates, urethane acrylates, and the like. Among these, preferable examples of the polyfunctional monomer include 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.
From the viewpoint of further exhibiting the effects of the present invention, the amount of the polyfunctional monomer used is preferably 0.005 to 10 parts by weight, more preferably 0.008 to 8 parts by weight, further preferably 0.01 to 7 parts by weight, further preferably 0.01 to 5 parts by weight, further preferably 0.01 to 4 parts by weight, particularly preferably 0.01 to 3 parts by weight, and most preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the base polymer. In addition, a polyfunctional monomer may be added as a base polymer to a so-called prepolymer having a low polymerization rate, and in this case, the prepolymer may be used as the base polymer.
(other Components)
The acrylic pressure-sensitive adhesive may contain, as required, various additives commonly used in the field of pressure-sensitive adhesives, such as a leveling agent, a crosslinking aid, a plasticizer, a softening agent, a filler, an antistatic agent, an antioxidant, an ultraviolet absorber, an antioxidant, and a light stabilizer. Conventionally known additives can be used for such various additives by a conventional method.
(static-resistant layer)
The protective film according to the embodiment of the present invention may have an antistatic layer on the surface of the base material layer opposite to the surface having the adhesive layer. In the protective film according to the embodiment of the present invention, the antistatic layer is provided on the surface of the base material layer opposite to the surface having the pressure-sensitive adhesive layer, so that the electrification of the protective film itself can be suppressed, and dust is less likely to be adsorbed.
Examples of the antistatic layer include a method of coating an antistatic resin containing an antistatic agent and a resin component, a conductive resin containing a conductive polymer and a conductive substance; a method of depositing or plating a conductive material.
Examples of the antistatic agent contained in the antistatic resin include quaternary ammonium salts, pyridinium salts, and cationic antistatic agents having a cationic functional group such as a primary amino group, a secondary amino group, or a tertiary amino group; anionic antistatic agents having anionic functional groups such as sulfonic acid salts, sulfuric acid ester salts, phosphonic acid salts, and phosphoric acid ester salts; amphoteric antistatic agents such as alkylbetaines and derivatives thereof, imidazolines and derivatives thereof, and alanines and derivatives thereof; nonionic antistatic agents such as aminoalcohols and derivatives thereof, glycerol and derivatives thereof, polyethylene glycols and derivatives thereof, and the like; and ion-conductive polymers obtained by polymerizing or copolymerizing the above-mentioned monomers having a cation-type, anion-type, or zwitterion-type ion-conductive group. These antistatic agents may be used in an amount of only 1 kind, or in an amount of 2 or more kinds.
Examples of the cationic antistatic agent include (meth) acrylate copolymers having a quaternary ammonium group such as alkyltrimethylammonium salts, acyloxyamidopropyltrimethylammonium methylsulfate, alkylbenzylmethylammonium salts, acylcholine chloride, and dimethylaminoethyl methacrylate; styrene copolymers having quaternary ammonium groups such as polyvinyl benzyl trimethyl ammonium chloride; and diallylamine copolymers having a quaternary ammonium group such as polydiallyldimethylammonium chloride. These antistatic agents may be used in an amount of only 1 kind, or in an amount of 2 or more kinds.
Examples of the anionic antistatic agent include alkylsulfonates, alkylbenzenesulfonates, alkylsulfate salts, alkyl ethoxysulfates, alkyl phosphate salts, and sulfonic acid group-containing styrene copolymers. These antistatic agents may be used in an amount of only 1 kind, or in an amount of 2 or more kinds.
Examples of the zwitterionic antistatic agent include alkyl betaines, alkyl imidazolium betaines, and carbonyl betaine graft copolymers. These antistatic agents may be used in an amount of only 1 kind, or in an amount of 2 or more kinds.
Examples of the nonionic antistatic agent include fatty acid alkanolamides, di (2-hydroxyethyl) alkylamines, polyoxyethylene alkylamines, fatty acid glycerides, polyoxyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl ethers, polyethylene glycols, polyoxyethylene diamines, copolymers of polyethers and polyesters with polyamides, and methoxypolyethylene glycol (meth) acrylates. These antistatic agents may be used in an amount of only 1 kind, or in an amount of 2 or more kinds.
Examples of the conductive polymer include polyaniline, polypyrrole, and polythiophene. These conductive polymers may be only 1 kind, or may be 2 or more kinds.
Examples of the conductive material include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, copper iodide, and alloys or mixtures thereof. These conductive materials may be only 1 kind, or 2 or more kinds.
As the resin component used for the antistatic resin and the conductive resin, general-purpose resins such as polyester resin, acrylic resin, polyethylene resin, urethane resin, melamine resin, epoxy resin, and the like can be used. In the case of a polymer type antistatic agent, the resin component may not be contained. Further, as the component of the antistatic resin, a methylolated or alkylolated melamine compound, urea compound, glyoxal compound, acrylamide compound; an epoxy compound; an isocyanate compound; and so on.
The antistatic layer can be formed, for example, by diluting the above antistatic resin, conductive polymer, conductive resin, or the like with an organic solvent or a solvent such as water, applying the coating solution to a substrate, or the like, and drying the coating solution.
Examples of the diluted solution for forming the antistatic layer include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, isopropanol, and water. These solvents may be used in a single amount of 1 kind, or in a plurality of amounts of 2 or more kinds.
As for the coating method in the formation of the antistatic layer, any and appropriate coating method can be appropriately used. Examples of such coating methods include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, impregnation, curtain coating, and the like.
As a method for vapor deposition or plating of the conductive material, any and suitable method can be suitably used. Examples of such a method include vacuum deposition, sputtering, ion plating, chemical deposition, spray pyrolysis, chemical plating, and plating.
The thickness of the antistatic layer may be any and appropriate thickness within a range not impairing the effects of the present invention. From the viewpoint of further exhibiting the effects of the present invention, the thickness of the antistatic layer is preferably 0.001 μm to 5 μm, and more preferably 0.005 μm to 1 μm.
Top coating
The protective film according to the embodiment of the present invention may have a top coat layer on the surface of the base material layer opposite to the surface having the adhesive layer. The top coat preferably contains a binder, more preferably a binder and a lubricant. When the protective film according to the embodiment of the present invention has a top coat layer, scratch resistance of the protective film is improved, which is a preferable embodiment.
< Binder >
The binder may be any and appropriate resin within a range not impairing the effects of the present invention. Such a resin is preferably at least 1 selected from the group consisting of polyester resins and urethane resins, from the viewpoint of further exhibiting the effects of the present invention.
(polyester resin)
When the binder contains a polyester resin, the number of the polyester resins may be 1 or 2 or more.
The polyester resin is preferably a resin containing a polyester as a main component. The content of the polyester in the polyester resin is preferably more than 50% by weight, more preferably 75% by weight or more, and further preferably 90% by weight or more.
The polyester preferably has a structure obtained by condensing at least 1 compound (polycarboxylic acid component) selected from polycarboxylic acids (preferably dicarboxylic acids) having 2 or more carboxyl groups in 1 molecule and derivatives thereof (anhydrides, esters, halides and the like of polycarboxylic acids) and at least 1 compound (polyol component) selected from polyhydric alcohols (preferably diols) having 2 or more hydroxyl groups in 1 molecule.
Examples of the compound usable as the polycarboxylic acid component include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, difluoromalonic acid, alkylmalonic acid, succinic acid, tetrafluorosuccinic acid, alkylsuccinic acid, (±) -malic acid, meso-tartaric acid, itaconic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, acetylenedicarboxylic acid, glutaric acid, hexafluoroglutaric acid, methylglutaric acid, glutaconic acid, adipic acid, dithioadipic acid, methyladipic acid, dimethyladipic acid, tetramethyladipic acid, methyleneadipic acid, muconic acid, galactaric acid, pimelic acid, suberic acid, perfluorosuberic acid, 3,3,6,6-tetramethylsuberic acid, azelaic acid, sebacic acid, perfluorosebacic acid, brassyldicarboxylic acid, dodecanedicarboxylic acid, tridecyldicarboxylic acid, and tetradecyldicarboxylic acid; alicyclic dicarboxylic acids such as cycloalkyldicarboxylic acids (e.g., 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid), 1,4- (2-norbornene) dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid (HIMIC acid), adamantanedicarboxylic acid, and spiroheptadicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, dithioisophthalic acid, methylisophthalic acid, dimethylisophthalic acid, chloromisophthalic acid, dichloroisophthalic acid, terephthalic acid, methylterephthalic acid, dimethylterephthalic acid, chloroterephthalic acid, bromoterephthalic acid, naphthalenedicarboxylic acid, fluorenone dicarboxylic acid, anthracenedicarboxylic acid, biphenyldicarboxylic acid, biphenylenedicarboxylic acid, dimethylbiphenylenedicarboxylic acid, 4,4 "-p-terphenylenedicarboxylic acid, 4,4" -p-tetrabiphenylenedicarboxylic acid, bibenzyldicarboxylic acid, azobenzenedicarboxylic acid, homopolyphthalic acid, phenylenediacetic acid, phenylenedipropionic acid, naphthalenedicarboxylic acid, naphthalenedipropionic acid, biphenyldiacetic acid, biphenyldipropionic acid, 3,3' - [4,4' - (methylene di-p-biphenylene) dipropionic acid, 4,4' -bibenzyl diacetic acid, 3,3' (4,4 ' -bibenzyl) dipropionic acid, and oxydiphenylenediacetic acid; anhydrides of any of the above polycarboxylic acids; esters (e.g., alkyl esters, monoesters, diesters, etc.) of any of the foregoing polycarboxylic acids; acid halides corresponding to any of the above-mentioned polycarboxylic acids (e.g., dicarboxylic acid chlorides); and the like.
Suitable examples of the compound usable as the polycarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, and anhydrides thereof; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, succinic acid, fumaric acid, maleic acid, HIMIC acid, 1,4-cyclohexanedicarboxylic acid, and anhydrides thereof; and lower alkyl esters of the above dicarboxylic acids (for example, esters with monoalcohols having 1 to 3 carbon atoms).
Examples of the compound usable as the polyol component include glycols such as ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, diethylene glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, benzene dimethanol, hydrogenated bisphenol A, and bisphenol A. Other examples include alkylene oxide adducts (e.g., ethylene oxide adducts, propylene oxide adducts, etc.) of these compounds.
The polyester resin preferably contains a water-dispersible polyester, more preferably a water-dispersible polyester as a main component. Such a water-dispersible polyester may be a polyester having improved water dispersibility by, for example, introducing a hydrophilic functional group (for example, at least 1 kind of hydrophilic functional group selected from sulfonic acid metal bases, carboxyl groups, ether groups, phosphoric acid groups, and the like) into a polymer. As a method for introducing a hydrophilic functional group into a polymer in this manner, any and suitable method such as a method of copolymerizing a compound having a hydrophilic functional group, a method of modifying a polyester or a precursor thereof (for example, a polycarboxylic acid component, a polyol component, an oligomer thereof, or the like) to generate a hydrophilic functional group, or the like can be suitably used. A preferable water-dispersible polyester includes a polyester (copolyester) copolymerized with a compound having a hydrophilic functional group.
The polyester resin used as the binder may contain a saturated polyester as a main component or an unsaturated polyester as a main component. The polyester resin is preferably a saturated polyester as a main component, and more preferably a saturated polyester (for example, a saturated copolyester) to which water dispersibility is imparted. Such a polyester resin (which can be prepared in the form of an aqueous dispersion) can be synthesized by an arbitrary and appropriate method, or a commercially available product can be easily obtained.
The molecular weight of the polyester resin is calculated by the weight average molecular weight (Mw) of standard polystyrene conversion measured by Gel Permeation Chromatography (GPC), preferably 0.5X 10 4 ～15×10 4 More preferably 1X 10 4 ～6×10 4 。
The glass transition temperature (Tg) of the polyester resin is preferably from 0 ℃ to 100 ℃, more preferably from 10 ℃ to 80 ℃.
(urethane resin)
When the binder contains a urethane resin, the number of the urethane resin may be 1 or 2 or more.
The urethane resin is preferably a urethane resin obtained by curing a composition containing a polyol (a) and a polyfunctional isocyanate compound (B).
The polyol (a) may be only 1 type or may be 2 or more types.
As the polyol (a), any arbitrary and suitable polyol can be used as long as it has 2 or more OH groups. Examples of the polyol (a) include a polyol (diol) having 2 OH groups, a polyol (triol) having 3 OH groups, a polyol (tetraol) having 4 OH groups, a polyol (pentaol) having 5 OH groups, and a polyol (hexaol) having 6 OH groups.
As the polyol (a), it is preferable to use a glycol having 2 or more OH groups, such as ethylene glycol or propylene glycol, as an essential component. By using a diol as an essential component, for example, a urethane-based cured resin having excellent strength of a coating film after curing, excellent adhesion to a base material, and excellent retention of an additive substance can be provided. The content ratio of the diol in the polyol (a) is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, even more preferably 70 to 100% by weight, even more preferably 90 to 100% by weight, particularly preferably 95 to 100% by weight, and most preferably substantially 100% by weight.
Examples of the polyol (A) include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, polyethylene glycol, polypropylene glycol, polyester polyol, poly, polycaprolactone polyol, polycarbonate polyol, castor oil polyol, and the like.
The polyester polyol can be obtained, for example, by esterification of a polyol component with an acid component.
Examples of the acid component include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4' -biphenyldicarboxylic acid, and anhydrides thereof.
Examples of the polyether polyol include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using water, low-molecular-weight polyols (such as propylene glycol, ethylene glycol, glycerol, trimethylolpropane, and pentaerythritol), bisphenols (such as bisphenol a), and dihydroxybenzenes (such as catechol, resorcinol, and hydroquinone) as initiators. Specific examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.
Examples of the polycaprolactone polyol include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as e-caprolactone and σ -valerolactone.
Examples of the polycarbonate polyol include polycarbonate polyols obtained by polycondensation of the above polyol component with phosgene; polycarbonate polyols obtained by subjecting the polyol component to ester exchange condensation with carbonic diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and dibenzyl carbonate; a copolymerized polycarbonate polyol obtained by using 2 or more of the above polyol components in combination; polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols and a carboxyl group-containing compound to an esterification reaction; polycarbonate polyols obtained by etherification of the above-mentioned various polycarbonate polyols with a hydroxyl group-containing compound; polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols and an ester compound to an ester exchange reaction; polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols and a hydroxyl group-containing compound to an ester exchange reaction; polyester polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols and a dicarboxylic acid compound to a polycondensation reaction; a copolymerized polyether polycarbonate polyol obtained by copolymerizing the above-mentioned various polycarbonate polyols with alkylene oxide; and the like.
Examples of the castor oil polyol include castor oil polyols obtained by reacting a castor oil fatty acid with the above polyol component. Specifically, for example, castor oil-based polyol obtained by reacting castor oil fatty acid with polypropylene glycol is exemplified.
The number of the polyfunctional isocyanate compounds (B) may be only 1, or may be 2 or more.
As the polyfunctional isocyanate compound (B), any and suitable polyfunctional isocyanate compound that can be used for the urethanization reaction can be used. Examples of the polyfunctional isocyanate compound (B) include polyfunctional aliphatic isocyanate compounds, polyfunctional alicyclic isocyanates, and polyfunctional aromatic isocyanate compounds.
Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and the like.
Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.
Examples of the polyfunctional aromatic diisocyanate compound include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2' -diphenylmethane diisocyanate, 4,4' -diphenylmethane diisocyanate, 4,4' -toluidine diisocyanate, 4,4' -diphenylether diisocyanate, 4,4' -diphenyldiisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate.
Examples of the polyfunctional isocyanate compound (B) include trimethylolpropane adducts, biurets obtained by reaction with water, and trimers having an isocyanurate ring of the above polyfunctional isocyanate compounds. Further, they may be used in combination.
The content of the polyfunctional isocyanate compound (B) is preferably 5 to 60% by weight, more preferably 8 to 60% by weight, and still more preferably 10 to 60% by weight, based on the polyol (a). By adjusting the content ratio of the polyfunctional isocyanate compound (B) within the above range, the effects of the present invention can be further exhibited.
Typically, the urethane resin is obtained by curing a composition containing a polyol (a) and a polyfunctional isocyanate compound (B). In such a composition, any and appropriate other components other than the polyol (a) and the polyfunctional isocyanate compound (B) may be contained within a range not impairing the effects of the present invention. Examples of such other components include catalysts, resin components other than the urethane resin, tackifiers, inorganic fillers, organic fillers, metal powders, pigments, foils, softeners, plasticizers, anti-aging agents, conductive agents, antioxidants, ultraviolet absorbers, light stabilizers, surface lubricants, leveling agents, preservatives, heat stabilizers, polymerization inhibitors, lubricants, and solvents.
As a method for obtaining a urethane resin by curing a composition containing the polyol (a) and the polyfunctional isocyanate compound (B), any and suitable method such as a urethanization reaction method using bulk polymerization, solution polymerization, or the like can be adopted within a range not impairing the effects of the present invention.
(other resins)
In the top coat layer, as the binder, other resins (for example, at least 1 resin selected from acrylic resins, acrylic-styrene resins, acrylic-silicone resins, polysilazane resins, fluorine resins, polyolefin resins) than the polyester resins and the urethane resins may be further contained within the limit that the performance of the protective film is not significantly impaired. In a preferred embodiment of the top coat layer, the binder of the top coat layer substantially consists of only at least 1 selected from the group consisting of polyester resins and urethane resins, and the proportion of at least 1 selected from the group consisting of polyester resins and urethane resins in the binder is preferably 98 to 100% by weight, more preferably 99 to 100% by weight, and still more preferably 99.5 to 100% by weight. The proportion of the binder in the entire top coat layer is preferably 15 to 95 wt%, more preferably 25 to 80 wt%.
< Lubricant >
As the lubricant, an ester (hereinafter, sometimes referred to as "wax ester") of a higher fatty acid and a higher alcohol is preferably contained.
The "higher fatty acid" is preferably a carboxylic acid having 8 or more carbon atoms, and the number of carbon atoms thereof is more preferably 10 or more, and still more preferably 10 to 40. The carboxylic acid is preferably a monocarboxylic acid.
The "higher alcohol" is preferably an alcohol having 6 or more carbon atoms, and the number of carbon atoms thereof is more preferably 10 or more, and still more preferably 10 to 40. The alcohol is preferably a monohydric or dihydric alcohol, more preferably a monohydric alcohol.
A top coat layer combining a composition comprising such a wax ester and the aforementioned binder is less likely to whiten even when kept under high temperature and humidity conditions. Therefore, a protective film provided with a substrate having such a top coat layer can form a film having higher appearance quality.
The reason why the top coat layer having the above composition achieves excellent whitening resistance (e.g., a property of being less likely to whiten even under high-temperature and high-humidity conditions) is, for example, as follows. That is, it is presumed that the silicone-based lubricant used conventionally functions to impart lubricity to the surface of the top coat layer by bleeding out to the surface. However, the degree of exudation of these silicone lubricants is likely to vary depending on the storage conditions (temperature, humidity, time and the like). Therefore, for example, when the amount of the silicone-based lubricant used is set so that proper lubricity can be obtained for a long period of time (for example, about 3 months) immediately after the production of the self-protective film when the film is kept under ordinary storage conditions (for example, 25 ℃ C., 50% RH), the lubricant bleeding excessively proceeds when the film is kept under high-temperature and high-humidity conditions (for example, 60 ℃ C., 95% RH) for two weeks. Such an excessively oozed silicone lubricant may cause whitening of the topcoat layer (and hence the protective film).
As a preferred embodiment of the top coat, a specific combination of a wax ester as a lubricant and a polyester resin as a binder is employed. If such a combination of the lubricant and the binder is used, the extent of exudation of the wax ester from the top coat layer is not easily affected by the storage conditions. This can improve the whitening resistance of the protective film.
As the wax ester, 1 or more of the compounds represented by the general formula (W) can be preferably used.
X-COO-Y(W)
X and Y in formula (W) are each independently preferably a hydrocarbon group having 10 to 40 carbon atoms, more preferably 10 to 35 carbon atoms, still more preferably 14 to 35 carbon atoms, and particularly preferably 20 to 32 carbon atoms. If the number of carbon atoms is too small, the effect of imparting lubricity to the top coat layer may be insufficient. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The hydrocarbon group is preferably a saturated hydrocarbon group. The hydrocarbon group may have an aromatic ring-containing structure, an aromatic ring-free structure (aliphatic hydrocarbon group), an aliphatic ring-containing structure (aliphatic hydrocarbon group), or a chain (including linear and branched hydrocarbon groups).
The wax ester is preferably a compound having a linear alkyl group having 10 to 40 carbon atoms, more preferably a compound having a linear alkyl group having 10 to 40 carbon atoms, each of X and Y in the formula (W) being independent of the other. Specific examples of such a compound include myricyl Cerolate (CH) 3 (CH 2 ) 24 COO(CH 2 ) 29 CH 3 ) Melissyl palmitate (CH) 3 (CH 2 ) 14 COO(CH 2 ) 29 CH 3 ) Cetyl palmitate (CH) 3 (CH 2 ) 14 COO(CH 2 ) 15 CH 3 ) Stearyl stearate (CH) 3 (CH 2 ) 16 COO(CH 2 ) 17 CH 3 ) And the like.
The melting point of the wax ester is preferably 50 ℃ or higher, more preferably 60 ℃ or higher, still more preferably 70 ℃ or higher, and particularly preferably 75 ℃ or higher. According to this wax ester, higher whitening resistance can be achieved. The melting point of the wax ester is preferably 100 ℃ or lower. Such a wax ester has a high effect of imparting lubricity, and therefore, a top coat having higher scratch resistance can be formed. From the viewpoint of ease of preparation of the aqueous dispersion of the wax ester, it is also preferable that the melting point of the wax ester is 100 ℃ or lower. As such a wax ester, melissa cerate, for example, can be preferably used.
As a raw material of the top coat layer, a natural wax containing such a wax ester can be used. The natural wax is preferably contained in an amount of more than 50 wt%, more preferably 65 wt% or more, and still more preferably 75 wt% or more of the wax ester (when 2 or more wax esters are contained, the total content thereof) based on the nonvolatile content (NV). Examples of such natural waxes include vegetable waxes such as carnauba wax (containing myricyl cerolate in an amount of preferably 60% by weight or more, more preferably 70% by weight or more, and still more preferably 80% by weight or more in general), and palm wax; animal such as beeswax, spermaceti; waxes, and the like. The melting point of the natural wax is preferably 50 ℃ or higher, more preferably 60 ℃ or higher, still more preferably 70 ℃ or higher, and particularly preferably 75 ℃ or higher. As a raw material of the top coat layer, a chemically synthesized wax ester may be used, or a product obtained by purifying a natural wax to improve the purity of the wax ester may be used. These raw materials may be only 1 kind or 2 or more kinds.
The proportion of the lubricant in the entire top coat layer is preferably 5 to 50 wt%, more preferably 10 to 40 wt%. If the content ratio of the lubricant is too small, scratch resistance may be easily reduced. If the content ratio of the lubricant is too large, the effect of improving the whitening resistance may be insufficient.
In the top coat layer, other lubricant may be further contained in addition to the wax ester. Examples of the other lubricant include various waxes other than wax esters such as petroleum waxes (paraffin wax and the like), mineral waxes (montan wax and the like), higher fatty acids (cerotic acid and the like), and neutral fats (palmitic acid triglyceride and the like). Further, the lubricant may contain a silicone-based lubricant, a fluorine-based lubricant, or the like in addition to the wax ester. A preferable embodiment of the top coat layer is a form substantially free of the silicone-based lubricant and the fluorine-based lubricant, and for example, the total content of the silicone-based lubricant and the fluorine-based lubricant is preferably 0.01 wt% or less of the entire top coat layer, and more preferably, the detection limit or less.
The top coat layer may contain additives such as an antistatic component, a crosslinking agent, an antioxidant, a colorant (pigment, dye, etc.), a fluidity modifier (thixotropic agent, thickener, etc.), a film-forming aid, a surfactant (defoaming agent, dispersant, etc.), and a preservative, as required.
< antistatic component of topcoat layer >
Preferred embodiments of the top coat contain an antistatic component. The antistatic component is a component that can exert an effect of preventing or suppressing electrification of the protective film. When the top coat layer contains an antistatic component, for example, an organic or inorganic conductive substance, various antistatic agents, and the like can be used as the antistatic component. In addition, an antistatic agent that can be used in the aforementioned antistatic layer can also be used.
Examples of the organic conductive material include quaternary ammonium salts, pyridinium salts, and cationic antistatic agents having a cationic functional group such as a primary amino group, a secondary amino group, or a tertiary amino group; anionic antistatic agents having anionic functional groups such as sulfonic acid salts, sulfuric acid ester salts, phosphonic acid salts, and phosphoric acid ester salts; amphoteric ion type antistatic agents such as alkyl betaine and derivatives thereof, imidazoline and derivatives thereof, and alanine and derivatives thereof; nonionic antistatic agents such as aminoalcohols and derivatives thereof, glycerol and derivatives thereof, polyethylene glycols and derivatives thereof, and the like; an ion-conductive polymer obtained by polymerizing or copolymerizing a monomer having the above-mentioned cationic, anionic or zwitterionic ion-conductive group (for example, quaternary ammonium hydroxide); conductive polymers such as polythiophene, polyaniline, polypyrrole, polyethyleneimine, and allylamine polymers; and the like. The number of such antistatic agents may be only 1, or may be 2 or more.
Examples of the inorganic conductive material include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, copper iodide, ITO (indium oxide/tin oxide), ATO (antimony oxide/tin oxide), and the like. The number of such inorganic conductive materials may be only 1, or may be 2 or more.
Examples of the antistatic agent include cationic antistatic agents, anionic antistatic agents, zwitterionic antistatic agents, and nonionic antistatic agents; and ion-conductive polymers obtained by polymerizing or copolymerizing monomers having the above-mentioned cation, anion, or zwitterion ion-conductive groups.
When the top coat contains an antistatic component, the antistatic component preferably contains an organic conductive substance. As the organic conductive substance, various conductive polymers can be preferably used. With this structure, both good antistatic properties and high scratch resistance can be achieved.
Examples of the conductive polymer include polythiophene, polyaniline, polypyrrole, polyethyleneimine, and an allylamine polymer. The number of such conductive polymers may be only 1, or may be 2 or more. In addition, can also be combined with other antistatic components (inorganic conductive material, antistatic agent) using.
The amount of the conductive polymer to be used is preferably 1 to 100 parts by weight, more preferably 2 to 70 parts by weight, and still more preferably 3 to 50 parts by weight, based on 100 parts by weight of the binder contained in the top coat layer. If the amount of the conductive polymer used is too small, the antistatic effect may be reduced. If the amount of the conductive polymer used is too large, there is a possibility that the compatibility of the conductive polymer in the top coat layer tends to be insufficient, the appearance quality of the top coat layer is deteriorated, or the solvent resistance is lowered.
As the conductive polymer, polythiophene and polyaniline can be preferably used. The weight average molecular weight Mw in terms of polystyrene of the polythiophene is preferably 40X 10 4 Hereinafter, more preferably 30 × 10 4 The following. The polyaniline preferably has a weight average molecular weight Mw in terms of polystyrene of 50X 10 4 Hereinafter, more preferably 30 × 10 4 The following. The weight average molecular weight Mw of the conductive polymer in terms of polystyrene is preferably 0.1X 10 4 Above, more preferably 0.5 × 10 4 The above. In the present specification, polythiophene refers to a polymer of unsubstituted or substituted thiophene. Examples of the substituted thiophene polymer include poly (3,4-ethylenedioxythiophene).
When a method of applying a coating material for forming a top coat layer to a substrate and drying or curing the coating material is employed as a method of forming a top coat layer, it is preferable to use a conductive polymer (aqueous conductive polymer solution) in which the conductive polymer is dissolved or dispersed in water as a conductive polymer for preparing the coating material. Such an aqueous conductive polymer solution can be prepared, for example, by dissolving or dispersing in water a conductive polymer having a hydrophilic functional group (a conductive polymer which can be synthesized by a method such as copolymerization of a monomer having a hydrophilic functional group in the molecule). Examples of the hydrophilic functional group include a sulfo group, an amino group, an amide group, an imino group, a hydroxyl group, a mercapto group, a hydrazine group, a carboxyl group, a quaternary ammonium group, and a sulfate group (-O-SO) 3 H) Phosphate groups (e.g., -O-PO (OH) 2 ) And the like. Such hydrophilic functional groups may form salts. Examples of commercially available polythiophene aqueous solutions include the "denatorn" series, which is a trade name manufactured by Nagase Chemtex corporation. Examples of commercially available polyaniline sulfonic acid aqueous solutions include trade name "aqua-PASS" manufactured by Mitsubishi Yang Zhushi.
In the preparation of the coating material, aqueous solutions of polythiophenes are preferably used. The polythiophene aqueous solution is preferably a polythiophene aqueous solution containing polystyrene sulfonate (PSS) (for example, a form in which PSS is added as a dopant to polythiophene). The polythiophene aqueous solution may contain polythiophene and PSS in a mass ratio of polythiophene to PSS of preferably 1:1 to 1. The total content of polythiophene and PSS in such an aqueous polythiophene solution is preferably 1 to 5% by weight. Examples of commercially available products of such an aqueous polythiophene solution include a product name "ベイトロン (Baytron)" of h.c. stark company. When the aqueous polythiophene solution containing PSS is used as described above, the total amount of polythiophene and PSS is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight, and still more preferably 25 to 70 parts by weight, based on 100 parts by weight of the binder.
The top coat layer may contain a conductive polymer and other 1 or more kinds of antistatic components (organic conductive substances other than the conductive polymer, inorganic conductive substances, antistatic agents, etc.) at the same time as necessary. The top coat layer is preferably substantially free of antistatic components other than the conductive polymer. That is, the antistatic component contained in the top coat layer is preferably substantially composed only of the conductive polymer.
< crosslinking agent >
The top coat preferably contains a crosslinking agent. As the crosslinking agent, a crosslinking agent such as a melamine-based crosslinking agent, an isocyanate-based crosslinking agent, and an epoxy-based crosslinking agent, which are generally used for crosslinking a resin, can be appropriately selected and used. By using such a crosslinking agent, at least 1 effect of improving scratch resistance, solvent resistance, print adhesion, and a friction coefficient (that is, lubricity) can be achieved. The crosslinking agent preferably contains a melamine-based crosslinking agent. The top coat layer may be one in which the crosslinking agent is substantially composed of only a melamine-based crosslinking agent (melamine-based resin) (i.e., one substantially free of a crosslinking agent other than the melamine-based crosslinking agent).
< one preferred mode of Top coat >
One preferred form of top coat is as follows: when the material of the base layer is at least 1 selected from polyimide and polyether ether ketone, the top coat layer contains a binder containing a urethane resin and an antistatic component. As described above, by using a binder containing a urethane resin as a binder of the antistatic component of the top coat layer, the top coat layer can be made excellent in coating formability on the surface of the base layer made of at least 1 material selected from polyimide and polyether ether ketone, can be made good in appearance, and can exhibit excellent antistatic properties.
The binder as the antistatic component of the top coat layer is preferably a binder containing a polyester resin in many cases, and the material of the base layer is a specific base layer selected from at least 1 of polyimide and polyether ether ketone, and the binder containing a polyester resin may have low affinity, and the appearance after the top coat layer is formed by coating may be deteriorated, and excellent antistatic property may not be exhibited. As described above, when the material of the base material layer is at least 1 selected from the group consisting of polyimide and polyetheretherketone, if the top coat layer is made to contain a binder containing a urethane resin and an antistatic component, the top coat layer can have excellent coating formability on the surface of the base material layer, can have a good appearance, and can exhibit excellent antistatic properties.
< formation of Top coat >
The top coat layer can be suitably formed by a method including imparting a liquid composition (top coat layer-forming coating material) obtained by dispersing or dissolving the above-described resin component and an additive used as needed in an appropriate solvent to the base material. For example, a method of applying the coating material to the first surface of the base material, drying the coating material, and optionally performing a curing treatment (heat treatment, ultraviolet treatment, or the like) can be preferably employed. The NV (nonvolatile content) of the coating material is preferably 5% by weight or less, more preferably 0.05 to 5% by weight, still more preferably 0.05 to 1% by weight, and particularly preferably 0.10 to 1% by weight. When the top coat layer is formed to have a small thickness, the NV of the coating material is preferably 0.05 wt% to 0.50 wt%, more preferably 0.10 wt% to 0.30 wt%. By using a coating material with low NV in this way, a more uniform top coat layer can be formed.
The solvent constituting the top coat layer-forming coating material is preferably a solvent capable of stably dissolving or dispersing the top coat layer-forming components. The solvent may be an organic solvent, water or a mixed solvent thereof. Examples of the organic solvent include esters such as ethyl acetate; ketones such as methyl ethyl ketone, acetone, and cyclohexanone; cyclic ethers such as Tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol and cyclohexanol; at least 1 kind of alkylene glycol monoalkyl ether (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether), and glycol ether such as dialkylene glycol monoalkyl ether. The solvent constituting the top coat layer-forming coating material is preferably water or a mixed solvent mainly composed of water (for example, a mixed solvent of water and ethanol).
< Property of topcoat layer >
The thickness of the top coat layer is preferably 3nm to 500nm, more preferably 3nm to 100nm, and still more preferably 3nm to 60nm. If the thickness of the top coat layer is too large, the transparency (light transmittance) of the protective film may be easily lowered. If the thickness of the top coat layer is too small, it may be difficult to form the top coat layer uniformly, and for example, the thickness of the top coat layer may vary greatly depending on the location, and thus, the appearance of the protective film may be easily uneven.
The thickness of the top coat layer can be grasped by observing the cross section of the top coat layer with a Transmission Electron Microscope (TEM). For example, a target sample (a substrate having a top coat layer formed thereon, a protective film provided on the substrate, or the like) is subjected to heavy metal staining treatment for the purpose of clarifying the top coat layer, then embedded with a resin, and TEM observation of a cross section of the sample is performed by a microtome method, and the obtained result can be preferably used as the thickness of the top coat layer. As the TEM, for example, a TEM (model "H-7650") manufactured by Hitachi corporation, or the like can be used. In the embodiments described later, with respect to the acceleration voltage: 100kV, multiplying power: the cross-sectional image obtained under the condition of 60000 times was subjected to binarization treatment, and the thickness of the top coat layer (average thickness in the field) was actually measured by dividing the length of the sample in the field by the cross-sectional area of the top coat layer. In the case where the top coat layer can be observed sufficiently clearly without heavy metal staining, the heavy metal staining treatment can be omitted. Alternatively, the thickness of the top coat layer may be obtained by calculating a calibration curve relating the thickness determined by TEM to the detection results of various thickness detection devices (for example, a surface roughness meter, an interferometric thickness meter, an infrared spectrometer, various X-ray diffractometers, and the like).
The surface resistance value measured on the surface of the top coat layer is preferably 10 12 Omega is less, more preferably 10 4 Ω～10 12 Ω, more preferably 10 4 Ω～10 11 Omega, particularly preferably 5X 10 4 Ω～10 10 Omega, most preferably 10 4 Ω～10 9 Omega. The protective film exhibiting such a surface resistance value can be suitably used as a protective film used in processing, transportation, or the like of an article which is not subjected to static electricity, such as a liquid crystal cell, a semiconductor device, or the like. The value of the surface resistance value can be calculated from the surface resistance value measured in an atmosphere of 23 ℃ and 50% RH using a commercially available insulation resistance measuring apparatus.
The coefficient of friction of the top coat layer is preferably 0.4 or less. When the top coat layer having a low friction coefficient is formed in this way, when a load (a load such as a scratch) is applied to the top coat layer, the load can be avoided along the surface of the top coat layer, and the frictional force caused by the load can be reduced. This makes it difficult for the top coat layer to be damaged by cohesion (damage mode in which the top coat layer is damaged inside) or by interfacial damage (damage mode in which the top coat layer is peeled off from the back surface of the substrate). Therefore, the protective film can be further prevented from being scratched. The lower limit of the friction coefficient is preferably 0.1 or more, and more preferably 0.15 or more, in consideration of balance with other characteristics (e.g., appearance quality, printability, etc.). The coefficient of friction can be determined by rubbing the surface of the topcoat layer with a vertical load of 40mN in a measuring environment of 23 ℃ and 50% RH, for example. The amount of lubricant may be set in such a way as to achieve a preferred coefficient of friction. In adjusting the friction coefficient, it is also effective to increase the crosslink density of the top coat layer by, for example, adding a crosslinking agent and adjusting the film forming conditions.
The surface of the top coat layer preferably has a surface capable of utilizing an oil ink (for example, using an oil marker) is easy to print. The protective film having such a top coat layer is preferably represented by a protective film in which an identification number or the like of an adherend to be protected is described during processing, transportation or the like of the adherend (for example, an optical component) in a state in which the protective film is attached. Therefore, a top coat layer having excellent printability in addition to excellent appearance quality is preferable. For example, a top coat layer having high printability to an oil-based ink of the type in which the solvent is alcohol-based and which contains a pigment is preferable. Further, a top coat layer in which the printed ink is not easily removed by friction or transfer (i.e., excellent printing adhesion) is preferable. The top coat layer preferably has a solvent resistance to such an extent that the printed matter does not significantly change in appearance even when wiped off with alcohol (e.g., ethanol) when the printing is corrected or eliminated.
Since the top coat layer preferably contains a wax ester as a lubricant, sufficient lubricity (for example, the above-described preferred friction coefficient) can be achieved without applying a further release treatment (for example, a treatment of applying an arbitrary and appropriate release treatment agent such as a silicone-based release agent or a long chain alkyl-based release agent and drying) to the surface of the top coat layer. Such a method of not applying a further peeling treatment to the surface of the top coat layer is preferable in that whitening due to the peeling treatment agent (for example, whitening due to storage under heated and humidified conditions) can be prevented from occurring. Further, it is also advantageous from the viewpoint of solvent resistance.
Other layers
The protective film according to the embodiment of the present invention may be also implemented by further including other layers in addition to the substrate, the adhesive layer and the top coat layer. Examples of the arrangement of the "other layer" include a space between the first surface (back surface) of the substrate and the top coat layer, a space between the second surface (front surface) of the substrate and the adhesive layer, and the like. The layer disposed between the back surface of the substrate and the top coat layer may be, for example, a layer containing an antistatic component (antistatic layer). The layer disposed between the front surface of the substrate and the adhesive layer may be, for example, a primer layer (anchor layer) for improving the anchorage of the adhesive layer to the second surface, an antistatic layer, or the like. The protective film may have a structure in which an antistatic layer is disposed on the front surface of the base material, an anchor layer is disposed on the antistatic layer, and a pressure-sensitive adhesive layer is disposed thereon.
"foldable apparatus and rollable apparatus
The protective film according to the embodiment of the present invention is excellent in flexibility and transparency, and therefore can be suitably used in, for example, a bendable device (bendable device), a foldable device (foldable device), and a rollable device (rollable device) having a movable bending portion. The protective film according to the embodiment of the present invention is particularly excellent in flexibility and transparency, and therefore can be suitably used in a foldable device (foldable device) and a rollable device (rollable device) which have been difficult to use so far.
The foldable device according to the embodiment of the present invention includes the protective film according to the embodiment of the present invention. The foldable device of the present invention may include any other member as long as it has the protective film according to the embodiment of the present invention.
The rollable device according to an embodiment of the present invention is provided with the protective film according to an embodiment of the present invention. The rollable device of the present invention may include any other member as long as it has the protective film according to the embodiment of the present invention.
Fig. 1 is a schematic cross-sectional view showing an embodiment of a foldable device according to an embodiment of the present invention as a representative example of one usage form of the protective film of the present invention. In fig. 1, a foldable device 1000 according to an embodiment of the present invention includes a cover film 10, an adhesive layer 20, a polarizing plate 30, an adhesive layer 40, a touch sensor 50, an adhesive layer 60, an OLED70, and a protective film 100 according to an embodiment of the present invention. In fig. 1, typically, the outermost layer of the OLED70 on the side of the protection film 100 according to the embodiment of the present invention is a polyimide substrate. Further, a barrier layer is preferably provided on the side of the polyimide substrate opposite to the protective film 100 according to the embodiment of the present invention. In fig. 1, a protective film 100 according to an embodiment of the present invention is composed of an adhesive layer 80 and a base material layer 90. The pressure-sensitive adhesive layers 20, 40, and 60 may be pressure-sensitive adhesive layers containing a pressure-sensitive adhesive having the same composition as the pressure-sensitive adhesive layer 80 constituting the protective film 100 of the present invention, or may be pressure-sensitive adhesive layers containing a pressure-sensitive adhesive having a different composition.
The protective film according to the embodiment of the present invention is excellent in flexibility and transparency, and therefore can be suitably present on the back surface (the opposite surface to the display surface) of, for example, a bendable device (bendable device) having a movable bending portion, a foldable device (foldable device), or a rollable device (rollable device). Fig. 1 is a diagram existing on the back side (the opposite side to the display side) of a foldable device (a device capable of being folded).
Examples
The present invention will be described more specifically below with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following description, "part" and "%" are based on weight unless otherwise specified.
< Observation of particles or aggregates of particles in substrate layer >
The inside of the substrate layer was observed with a digital microscope (BX 51, manufactured by OLYMPUS Co., ltd., objective lens: 20X/0.40 BD P), and the Feret diameter of the particles or the aggregates of the particles in the substrate layer was measured. Then, per unit area (0.02 mm) 2 ) The case where the number of particles or aggregates of particles having a Ferrett diameter of 1 μm or more observed in (1) is 10 or more is referred to as "plural", and the case where 9 or less are referred to as "substantially not included".
< evaluation of yield >
10cm of protective film was applied by visual inspection 2 Foreign matter inspection of area, and 0.1mm was performed by means of microscope (USH 140CCD-L1, product of Song electric House Co., ltd.) 2 And (4) inspecting the area of foreign matters. In the foreign matter inspection by visual observation, a sample in which 1 or more foreign matters of 50 μm or more are detected is regarded as "defective", and in the inspection by microscope, the granular, needle-like or irregular-shaped foreign matters in a microscope image are obtained by an image processing software (imageJ)The sample having an area of 0.1% or more of the substance or the aggregate thereof was regarded as "failed".
When a sample that is not "defective" in both visual inspection and microscopic image inspection is used as a reference for the final "non-defective product" and is manufactured with n =100, a case where the number of non-defective products is less than 50% is regarded as x, and a case where the number of non-defective products is 50% or more is regarded as good. The samples having a transmittance of 40% or less or a haze of 10% or more of the protective film cannot be visually inspected accurately, and therefore, they are good as described above and good as "x".
< surface roughness Ra >
The outermost surface of the protective film on the side opposite to the adhesive layer when viewed from the base layer was measured for surface roughness by using new view7300 (manufactured by ZYGO corporation) with a zoom lens (inner lens) of 1.00x and an objective lens of 2.5x/0.075 TI ofn22 WD 10.3 (manufactured by Nikon corporation), and Ra was calculated using analytical software (Metro Pro).
< bending test >
The flat protective film was fixed so as to be sandwiched between the silicone-treated surfaces of the silicone-treated separators with the pressure-sensitive adhesive layer surface facing outward and the protective film being bent at 6 Φ as shown in fig. 2, and held at 90 ℃ for 48 hours. Thereafter, the film was released from the bend, left at 23 ℃ and 50% RH for 24 hours, and then the angle of the bent film was measured. The state of the steel sheet completely returned to the original state is denoted by 180 degrees, and the bent state when the steel sheet was originally fixed is denoted by 0 degrees.
< measurement of haze and Total light transmittance >
Calculated by using a haze meter HM-150 (color technology research on village, ltd.) according to JIS-K-7136 using a haze (%) = (Td/Tt) × 100 (Td: diffusive transmittance, tt: total light transmittance). The total light transmittance was measured in accordance with JIS-K-7316.
< Young's modulus >
The sample piece was cut into a strip having a width of 10mm, and the strip-shaped sample piece was stretched and measured in the longitudinal direction at a distance of 100mm between chucks in a temperature environment of 25 ℃ by using a universal tensile compression Tester (TENSILON), and the Young' S modulus was determined from the S-S (string-Strength) curve obtained. As the measurement conditions, the drawing speed was 200mm/min and the chuck pitch was 50mm. The Young' S modulus was determined from the S-S curve as follows: a graph of an S-S curve is prepared, and a tangent (linear expression) is drawn to the graph within a displacement range of 1mm to 2mm, and the slope of the tangent is determined. The thickness is calculated using the thickness of the substrate layer.
< adhesion >
The protective film was cut into a width of 25mm and a length of 150mm to prepare a sample for evaluation. The surface of the adhesive layer of the sample for evaluation was attached to a glass plate (MICRO SILDE GLASS S, product name, manufactured by Sonlang Nitri Kogyo Co., ltd.) by reciprocating a 2.0kg roller once at a temperature of 23 ℃ and a humidity of 50% RH. After aging for 30 minutes in an atmosphere of 23 ℃ and 50% RH, peeling was carried out using a universal tensile testing machine (product name: TCM-1kNB, manufactured by MINEBEA Inc.) under conditions of a peeling angle of 180 degrees and a tensile rate of 300 mm/minute, and the adhesive force was measured.
< surface resistance value >
The surface resistance value was measured using a resistivity meter (manufactured by Mitsubishi chemical analysis, "Hiresta UP MCP-HT 450") under conditions that the URS probe was brought into contact with the surface of the protective film on which the pressure-sensitive adhesive layer was not provided, and the voltage application was 100V for 10 seconds.
< storage modulus G' and glass transition temperature >
Only the pressure-sensitive adhesive layer was taken out of the protective film, and the resultant film was laminated to a thickness of about 1.5mm to obtain a sample for measurement. The dynamic viscoelasticity was measured under the following conditions using "Advanced Rheological Expansion System (ARES)" manufactured by Rheometric Scientific. The storage modulus G' and the loss tangent tan. Delta. At each temperature were read from the measurement results. Further, the temperature at which tan δ becomes maximum is taken as the glass transition temperature (Tg) of the adhesive layer.
(measurement conditions)
Deformation mode: distortion of
Measuring frequency: 1Hz
Temperature rise rate: 5 ℃ per minute
The shape is as follows: parallel plate 7.9mm phi
< repeated bending test (evaluation of bending durability) >
The release liner was peeled off from the protective film, and the resultant was bonded to UPILEX 75S (product of Utsu Kaisha) having a thickness of 75 μm and pressure-bonded thereto by a hand roller. The laminate was cut into a size of 50mm × 100mm, and autoclave-treated at 35 ℃ and 0.35MPa for 15 minutes to obtain a test piece. A bending jig was attached to the short side of the test piece using a plane-like unloaded U-shaped stretching tester (manufactured by YUASA SYSTEM), and a repeated bending test was performed in a constant temperature bath at 25 ℃ and-20 ℃ with the surface of the test piece on the UPILEX 75S side as the outside under the following conditions.
(test conditions)
Bending radius: 3mm
Bending angle: 180 degree
Bending speed: 1 second/time
The bending times are as follows: 20 ten thousand times
The test piece after the repeated bending test was visually confirmed and evaluated according to the following criteria.
Good: the pressure-sensitive adhesive layer and the base material layer were not peeled off, and no air bubbles were observed to be mixed into the adhesion interface.
X: the pressure-sensitive adhesive layer and the base material layer are peeled off or bubbles are generated at the bonding interface.
[ production example 1]: preparation of adhesive composition A
2-ethylhexyl acrylate (2 EHA) as a monomer component: 63 parts by weight of N-vinyl-2-pyrrolidone (NVP): 15 parts by weight, methyl Methacrylate (MMA): 9 parts by weight, 2-hydroxyethyl acrylate (HEA): 13 parts by weight of 2,2' -azobisisobutyronitrile as a polymerization initiator: 0.2 parts by weight and ethyl acetate as a polymerization solvent: 133 parts by weight of the reaction solution was put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this manner, the temperature was raised to 65 ℃ to allow reaction for 10 hours, and then ethyl acetate was added to obtain a solution of the acrylic polymer (a) having a solid content concentration of 30 wt%.
Next, to the solution of the acrylic polymer (a), an isocyanate-based crosslinking agent (trade name "TAKENATE D N", manufactured by mitsui chemical) was added in an amount of 1 part by weight in terms of solid content to 100 parts by weight of the acrylic polymer (a) (solid content), to prepare an adhesive composition a.
The compositions are summarized in table 1.
[ production example 2]: preparation of adhesive composition B
(preparation of oligomer (1))
Dicyclopentanyl methacrylate (DCPMA) as a monomer component: 60 parts by weight and Methyl Methacrylate (MMA): 40 parts by weight of alpha-thioglycerol as a chain transfer agent: 3.5 parts by weight and toluene as polymerization solvent: 100 parts by weight were mixed and stirred at 70 ℃ for 1 hour under a nitrogen atmosphere. Next, 2,2' -Azobisisobutyronitrile (AIBN): 0.2 part by weight, reacted at 70 ℃ for 2 hours, then heated to 80 ℃ and reacted for 2 hours. Thereafter, the reaction solution was heated to 130 ℃ and dried to remove toluene, the chain transfer agent and the unreacted monomer, thereby obtaining a solid acrylic oligomer (1)). The weight average molecular weight of the oligomer (1) was 5100, and the glass transition temperature (Tg) was 130 ℃.
(preparation of prepolymer composition)
As a monomer component for forming a prepolymer, lauryl Acrylate (LA): 35 parts by weight of 2-ethylhexyl acrylate (2 EHA): 49 parts by weight of 4-hydroxybutyl acrylate (4 HBA): 7 parts by weight and N-vinyl-2-pyrrolidone (NVP): 9 parts by weight, and "Irgacure 184" manufactured by BASF corporation as a photopolymerization initiator: 0.015 part by weight of the prepolymer was polymerized by irradiation with ultraviolet light to obtain a prepolymer composition B (polymerization rate: about 10%).
(preparation of adhesive composition)
To prepolymer composition B:100 parts by weight of a post-additive component of 1,6-hexanediol diacrylate (HDDA): 0.07 parts by weight of an oligomer (1): 3 parts by weight of a silane coupling agent ("KBM 403" manufactured by shin-Etsu chemical Co., ltd.): after 0.3 part by weight, they were uniformly mixed to prepare an adhesive composition B.
The compositions are summarized in table 1.
[ production example 3]: preparation of adhesive composition C
(preparation of prepolymer composition)
As a monomer component for forming a prepolymer, lauryl Acrylate (LA): 60 parts by weight of 2-ethylhexyl acrylate (2 EHA): 22 parts by weight, 4-hydroxybutyl acrylate (4 HBA): 8 parts by weight and N-vinyl-2-pyrrolidone (NVP): 10 parts by weight, and "Irgacure 184" manufactured by BASF corporation as a photopolymerization initiator: 0.015 part by weight was polymerized by irradiation with ultraviolet light to obtain a prepolymer composition C (polymerization rate: about 10%).
(preparation of adhesive composition)
To prepolymer composition C:100 parts by weight of a post-addition component 1,6 hexanediol diacrylate (HDDA): 0.06 part by weight of oligomer (1) prepared in production example 2: 3 parts by weight of a silane coupling agent ("KBM 403" manufactured by shin-Etsu chemical Co., ltd.): after 0.3 part by weight, they were uniformly mixed to prepare an adhesive composition C.
The compositions are summarized in table 1.
[ production example 4]: preparation of adhesive composition D
(preparation of acrylic Polymer D)
Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, lauryl Acrylate (LA): 19.4 parts by weight of 2-ethylhexyl acrylate (2 EHA): 67.9 parts by weight, n-Butyl Acrylate (BA): 7.8 parts by weight of 4-hydroxybutyl acrylate (4 HBA): 3.9 parts by weight and N-vinyl-2-pyrrolidone (NVP): 1.0 part by weight, and 2,2' -Azobisisobutyronitrile (AIBN) as a polymerization initiator: 0.1 part by weight, so that the total concentration of these to 42% by weight of ethyl acetate, while slowly stirring and consuming 1 hours of nitrogen replacement, flask liquid temperature to 58 degrees C nearby, for 5 hours of polymerization reaction, after the reaction, adding ethyl acetate, to the polymer concentration to 32% by weight of adjustment, get acrylic polymer D solution. The weight average molecular weight of the acrylic polymer D was 157 ten thousand.
(preparation of adhesive composition D)
Mixing an acrylic polymer D:100 parts by weight of CORONATE HX (available from Tosoh corporation, isocyanate-based crosslinking agent) as a crosslinking agent: 0.05 part by weight of the oligomer (1) prepared in production example 2: 2 parts by weight of Irganox 1010 (manufactured by BASF corporation) as an antioxidant: 0.3 part by weight of NACEM IRON (III) (manufactured by Nippon chemical industries Co., ltd.): 0.01 parts by weight were mixed and sufficiently stirred, and diluted with ethyl acetate and acetylacetone in an amount of 2% by weight as a solvent so that the total solid content became 21% by weight, thereby preparing an adhesive composition D.
The compositions are summarized in table 1.
[ production example 5]: preparation of adhesive composition E
(preparation of acrylic Polymer E)
Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a condenser, lauryl Acrylate (LA): 8.0 parts by weight of 2-ethylhexyl acrylate (2 EHA): 70.3 parts by weight of n-Butyl Acrylate (BA): 20.1 parts by weight of 4-hydroxybutyl acrylate (4 HBA): 1.0 parts by weight and N-vinyl-2-pyrrolidone (NVP): 0.6 parts by weight, and 2,2' -Azobisisobutyronitrile (AIBN) as a polymerization initiator: 0.1 part by weight, so that their total concentration reaches 47 wt% into ethyl acetate, while slowly stirring and consuming 1 hours to nitrogen replacement, flask liquid temperature to 56 degrees C nearby, 6 hours of polymerization reaction, after the reaction, adding ethyl acetate, to the polymer concentration to 24 wt% adjustment, get acrylic polymer E solution. The weight average molecular weight of the acrylic polymer E was 209 ten thousand.
(preparation of adhesive composition E)
Mixing an acrylic polymer E:100 parts by weight of CORONATE HX (available from Tosoh corporation, isocyanate-based crosslinking agent) as a crosslinking agent: 0.03 part by weight of the oligomer (1) prepared in production example 2: 5 parts by weight of Irganox 1010 (manufactured by BASF Co., ltd.) as an antioxidant: 0.3 part by weight of NACEM IRON (III) (manufactured by Nippon chemical industries Co., ltd.): 0.01 parts by weight of the components were mixed and sufficiently stirred, and the mixture was diluted with ethyl acetate and acetylacetone in an amount of 2 wt% which was a solvent so that the total solid content became 21 wt%, thereby preparing an adhesive composition E.
The compositions are summarized in table 1.
[ production example 6]: preparation of adhesive composition F
(preparation of adhesive composition F)
The acrylic polymer E prepared in production example 5: 100 parts by weight of a peroxide (NYPER BMT-40SV, manufactured by Nippon fat and oil Co., ltd.) as a crosslinking agent: 0.25 part by weight of the oligomer (1) prepared in production example 2: 3 parts by weight of Irganox 1010 (manufactured by BASF Co., ltd.) as an antioxidant: 0.3 part by weight of NACEM IRON (III) (manufactured by Nippon chemical industries Co., ltd.): 0.01 parts by weight were mixed and sufficiently stirred, and diluted with ethyl acetate and acetylacetone in an amount of 2% by weight as a solvent so that the solid content of the whole became 21% by weight, thereby preparing an adhesive composition F.
The compositions are summarized in table 1.
[ production example 7]: preparation of adhesive composition G
(preparation of prepolymer composition)
As a monomer component for forming a prepolymer, lauryl Acrylate (LA): 99 parts by weight and 4-hydroxybutyl acrylate (4 HBA): 1 part by weight, and "Irgacure 184" made by BASF as a photopolymerization initiator: 0.015 part by weight of the resulting mixture was compounded, and polymerization was carried out by irradiation with ultraviolet light to obtain a prepolymer composition G (polymerization rate: about 10%).
(preparation of adhesive composition)
To prepolymer composition G:100 parts by weight of a post-additive component of 1,6-hexanediol diacrylate (HDDA): 0.30 part by weight and a silane coupling agent ("KBM 403" manufactured by shin-Etsu chemical Co., ltd.): after 0.3 part by weight, they were uniformly mixed to prepare an adhesive composition G.
The compositions are summarized in table 1.
[ Table 1]
Figure BDA0003403850940000561
[ example 1]
A commercially available release liner (DIAFOIL MRF-38", manufactured by Mitsubishi resin corporation) was prepared. The pressure-sensitive adhesive composition a was applied to one surface (release surface) of the release liner so that the thickness after drying became 25 μm, and dried at 130 ℃ for 3 minutes. In this manner, a pressure-sensitive adhesive layer having a thickness of 25 μm and comprising the acrylic pressure-sensitive adhesive a corresponding to the pressure-sensitive adhesive composition a was formed on the release surface of the release liner.
As the base material layer, a polyimide-based base material (trade name "UPILEX-25S", product of Udo Kyoho) having a thickness of 25 μm was prepared. The pressure-sensitive adhesive layer formed on the release liner is bonded to one surface of the base material layer. The release liner remains directly on the adhesive layer to protect the surface of the adhesive layer (adhesive layer side). The resulting structure was passed through a laminator (0.3 MPa, speed 0.5 m/min) at 80 ℃ for 1 time, and then cured in an oven at 50 ℃ for 1 day. Thus, a protective film (1) was obtained.
The results are shown in Table 2.
[ example 2]
A protective film (2) was obtained in the same manner as in example 1 except that a polyimide-based substrate (trade name "UPILEX-50RN", product of Udo Kyoho) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
[ example 3]
A protective film (3) was obtained in the same manner as in example 1, except that a Polyetheretherketone (PEEK) base material (trade name "EXPEEK", manufactured by KURABO corporation) having a thickness of 25 μm was used as the base material layer.
The results are shown in Table 2.
[ example 4]
A protective film (4) was obtained in the same manner as in example 1 except that a polyimide-based substrate (trade name "NEOPULIM S100", manufactured by Mitsubishi gas chemical Co., ltd.) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
[ example 5]
A protective film (5) was obtained in the same manner as in example 1, except that a polyimide-based substrate (trade name "UPILEX-50S", product of Updeshi K.K.) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
[ example 6]
A protective film (6) was obtained in the same manner as in example 1 except that a PEN-based substrate (trade name "PEN Q51", manufactured by Dithion Co., ltd.) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
[ example 7]
A polyethylene terephthalate (PET) film (DIAFOIL MRF75, manufactured by Mitsubishi chemical corporation) having a thickness of 75 μm and provided with a silicone-based release layer on the surface thereof was used as a substrate (also used as a heavy release film), and the adhesive composition B was applied to the substrate to a thickness of 25 μm to form a coating layer. A75 μm thick PET film ("DIAFOIL MRE75" manufactured by Mitsubishi chemical corporation) having one side subjected to a silicone release treatment was laminated on the coating layer as a cover sheet (also serving as a light release film). From the cover sheet side, the irradiation intensity of the irradiation surface directly below the lamp was 5mW/cm 2 The laminate was irradiated with ultraviolet light and photo-cured to obtain a pressure-sensitive adhesive sheet having a thickness of 25 μm.
As the base material layer, a polyimide-based base material (trade name "UPILEX-50S", product of Udo Kaisha) having a thickness of 50 μm was prepared. The light release film of the pressure-sensitive adhesive sheet was peeled off, and the pressure-sensitive adhesive layer was bonded to one surface of the base material layer. The heavy release film is left directly on the pressure-sensitive adhesive layer to protect the surface of the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer side). The resulting structure was passed through a laminator (0.3 MPa, speed 0.5 m/min) at 80 ℃ for 1 time, and then cured in an oven at 50 ℃ for 1 day. Thus, a protective film (7) was obtained.
The results are shown in Table 2.
[ example 8]
A protective film (8) was obtained in the same manner as in example 7, except that the pressure-sensitive adhesive composition C was used instead of the pressure-sensitive adhesive composition B.
The results are shown in Table 2.
[ example 9]
A protective film (9) was obtained in the same manner as in example 5, except that the pressure-sensitive adhesive composition D was used instead of the pressure-sensitive adhesive composition a.
The results are shown in Table 2.
[ example 10]
A protective film (10) was obtained in the same manner as in example 5, except that the pressure-sensitive adhesive composition E was used instead of the pressure-sensitive adhesive composition a.
The results are shown in Table 2.
[ example 11]
A commercially available release liner ("DIAFOIL MRF-38", manufactured by Mitsubishi resin corporation) was prepared. On one side (release side) of the release liner, adhesive composition F was applied so that the dried thickness became 25 μm, and dried at 155 ℃ for 3 minutes. In this manner, a pressure-sensitive adhesive layer having a thickness of 25 μm and comprising an acrylic pressure-sensitive adhesive F corresponding to the pressure-sensitive adhesive composition F was formed on the release surface of the release liner.
As the base material layer, a polyimide-based base material (trade name "UPILEX-50S", product of Udo Kaisha) having a thickness of 50 μm was prepared. The pressure-sensitive adhesive layer formed on the release liner is bonded to one surface of the base material layer. The release liner direct is left on the adhesive layer and is then left on the adhesive layer, for protecting the surface of the adhesive layer (adhesive layer side). The resulting structure was passed through a laminator (0.3 MPa, speed 0.5 m/min) at 80 ℃ for 1 time, and then cured in an oven at 50 ℃ for 1 day. Thus, a protective film (11) was obtained.
The results are shown in Table 2.
[ example 12]
A protective film (12) was obtained in the same manner as in example 7, except that the pressure-sensitive adhesive composition G was used instead of the pressure-sensitive adhesive composition B.
The results are shown in Table 2.
Comparative example 1
A protective film (C1) was obtained in the same manner as in example 1, except that a polyester-based substrate (trade name "Lumiror S10", manufactured by Toray corporation) having a thickness of 25 μm was used as the substrate layer.
The results are shown in Table 2.
Comparative example 2
A protective film (C2) was obtained in the same manner as in example 1, except that a polyester-based substrate (trade name "Lumiror S10", manufactured by Toray corporation) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
Comparative example 3
A protective film (C3) was obtained in the same manner as in example 1, except that a polyimide-based substrate (trade name "KAPTON200H", manufactured by Toledu Pont) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
Comparative example 4
A protective film (C4) was obtained in the same manner as in example 1, except that a polyimide-based substrate (trade name "PIXEO BP", manufactured by KANEKA) having a thickness of 50 μm was used as the substrate layer.
The results are shown in Table 2.
[ Table 2]
Figure BDA0003403850940000611
Industrial applicability
The protective film of the present invention has excellent bending recovery properties, does not damage a barrier layer even when bonded to the back side of a polyimide substrate having the barrier layer, has excellent transparency, and has excellent foreign matter inspection properties, and therefore can be suitably used in, for example, a bendable device (bendable device), a foldable device (foldable device), and a rollable device (rollable device) having a movable bending portion.
Description of the reference numerals
1000. Foldable device
100. Protective film
10. Cover film
20. Adhesive layer
30. Polarizing plate
40. Adhesive layer
50. Touch sensor
60. Adhesive layer
70 OLED
80. Adhesive layer
90. Substrate layer
1 phi 6 glass rod
2. Silicone treatment separator
3. Adhesive layer
4. Fixed glass

Claims (27)

1. A protective film is directly bonded to a polyimide substrate,
which comprises a base material layer and an adhesive layer,
observing the inside of the substrate layer with a digital microscope, and measuring the Ferrett diameter of the particles or aggregates of the particles in the substrate layer at 0.02mm per unit area 2 The number of particles or aggregates of particles having a Ferrett diameter of 1 μm or more observed in (2) is 9 or less.
2. The protective film according to claim 1, wherein a top coat layer is provided on a surface of the substrate layer opposite to the surface having the adhesive layer.
3. The protective film according to claim 2, wherein the top coat layer contains a binder containing at least 1 selected from polyester resins and urethane-based resins.
4. The protective film according to claim 3, wherein the adhesive comprises a urethane-based resin.
5. The protective film of any one of claims 2~4 wherein the topcoat contains an antistatic component.
6. The protective film of any one of claims 1~4 wherein the substrate layer has a young's modulus of 6.0 x 10 at 23 degrees c 7 Pa or above.
7. The protective film of any one of claims 1~4 wherein the material of the substrate layer is at least 1 selected from polyimide and polyetheretherketone.
8. The protective film according to claim 1, wherein a surface of the base material layer opposite to the surface having the adhesive layer has a top coat layer containing a binder and an antistatic component, the binder contains a urethane resin, and the material of the base material layer is at least 1 selected from polyimide and polyether ether ketone.
9. The protective film of any one of claims 1~4 wherein after bending at 6 Φ and holding at 90 ℃ for 48 hours, the bend is released and left at 23 ℃, 50% rh for 24 hours at a bend angle of 60-180 degrees.
10. The protective film of any one of claims 1~4 having a total light transmission of 40% or greater.
11. The protective film of any one of claims 1~4 having a haze of 10% or less.
12. The protective film of claim 1~4 wherein the adhesive layer has an adhesion to glass sheet of 1N/25mm or greater at 23 ℃, a draw rate of 300 mm/min, and 180 degree peel.
13. The protective film of any one of claims 1~4 wherein the adhesive layer has a storage modulus at 25 ℃ of 75kPa or less.
14. The protective film of any one of claims 1~4 wherein the adhesive layer has a Tg of-10 ℃ or less.
15. The protective film of any one of claims 1~4 wherein the adhesive layer comprises an acrylic adhesive comprising an acrylic polymer as a base polymer.
16. The protective film according to claim 15, wherein the acrylic polymer is obtained by polymerization of a monomer component (M) in which R is represented by formula (1) 1 Is a hydrogen atom or a methyl group, R 2 The content ratio of the alkyl (meth) acrylate (m 1) which is a C10-20 chain alkyl group is 5 to 65 wt%,
CH 2 ＝C（R 1 ）COOR 2 （1）。
17. the protective film according to claim 16, wherein the monomer component (M) contains 2-ethylhexyl acrylate in a proportion of 15 wt% to 85 wt%.
18. The protective film according to claim 17, wherein the total content ratio of the alkyl (meth) acrylate (M1) to the 2-ethylhexyl acrylate in the monomer component (M) is 65 to 98% by weight.
19. The protective film according to any one of claims 16 to 18,wherein R in the alkyl (meth) acrylate (m 1) 2 Is a chain alkyl of C10-13.
20. The protective film according to claim 19, wherein the alkyl (meth) acrylate (m 1) is lauryl acrylate.
21. The protective film according to any one of claims 16 to 18, wherein the monomer component (M) contains at least 1 selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.
22. The protective film of any one of claims 1~4 attached to a foldable member.
23. The protective film of claim 22, wherein the foldable member is an OLED.
24. The protective film of any one of claims 1~4 attached to a crimpable member.
25. The protective film of claim 24, wherein the crimpable member is an OLED.
26. A foldable device comprising the protective film according to any one of claims 1 to 21.
27. A crimpable device provided with the protective film according to any one of claims 1 to 21.
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