CN117359926A

CN117359926A - Method for producing resin film

Info

Publication number: CN117359926A
Application number: CN202310818555.6A
Authority: CN
Inventors: 中原步梦; 荻野真悠子
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2022-07-07
Filing date: 2023-07-05
Publication date: 2024-01-09
Also published as: JP2024008151A; KR20240007072A; TW202408782A

Abstract

Provided is a method for producing a resin film which is less likely to peel from an adherend even when exposed to a high-temperature and high-humidity environment in a state of being bonded to the adherend via an adhesive layer or an adhesive layer. The method for producing a resin film of the present invention comprises a heating step of heating a raw material film so that the ratio of the shrinkage rate of the resin film when heated at a temperature of 120 ℃ for 5 minutes to the expansion rate of the resin film when stored at a temperature of 85 ℃ and a humidity of 85% RH for 30 minutes [ the former/the latter ] is 0.3 to 2.5.

Description

Method for producing resin film

Technical Field

The present invention relates to a method for producing a resin film.

Background

As a material for bonding members to each other, an adhesive sheet or an adhesive sheet is widely used, in which a resin film is used as a base material and an adhesive layer or an adhesive layer is laminated on both surfaces of the base material (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2002-303730

Disclosure of Invention

Problems to be solved by the invention

However, conventional pressure-sensitive adhesive sheets and pressure-sensitive adhesive sheets may be as follows: when these sheets are exposed to a high-temperature and high-humidity environment in a state of being bonded to an adherend, separation occurs between the sheets and the adherend.

Accordingly, an object of the present invention is to provide a method for producing a resin film which is less likely to peel from an adherend even when exposed to a high-temperature and high-humidity environment in a state of being bonded to the adherend via an adhesive layer or an adhesive layer.

Solution for solving the problem

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that, when a resin film obtained by heating a raw material film so that the ratio of shrinkage rate at heating to expansion rate in a high-temperature and high-humidity environment falls within a specific range is used as a base material for an adhesive sheet or an adhesive sheet, peeling is less likely to occur between the adhesive sheet or the adhesive sheet and an adherend even when the adhesive sheet is exposed to a high-temperature and high-humidity environment in a state of being bonded to the adherend. The present invention has been completed based on these findings.

The present invention provides a method for producing a resin film, comprising a heating step of heating a raw material film so that the ratio [ the former/the latter ] of the shrinkage ratio of the resin film when heated at a temperature of 120 ℃ for 5 minutes to the expansion ratio when stored at a temperature of 85 ℃ and a humidity of 85% RH for 30 minutes is 0.3 to 2.5.

In the above production method, it is preferable that the raw material film is heated while applying a tensile stress to the raw material film in the heating step.

In the above-described production method, it is preferable that in the heating step, the raw material film is heated while applying a tensile stress in at least one direction.

In the above production method, it is preferable that warm air is blown from at least one surface of the raw material film in the heating step and the raw material film is heated.

In the above production method, the raw material film is preferably heated while being conveyed in the heating step.

The production method preferably includes a winding step of stretching the raw material film in the longitudinal direction after the heating step and winding the raw material film to obtain a resin film blank in a roll shape.

ADVANTAGEOUS EFFECTS OF INVENTION

The resin film obtained by the production method of the present invention is less likely to peel from an adherend even when exposed to a high-temperature and high-humidity environment in a state of being bonded to the adherend via an adhesive layer or an adhesive layer. Therefore, for example, when the resin film obtained by the production method of the present invention is used as a base material for an adhesive sheet or an adhesive sheet, peeling is less likely to occur between the adhesive sheet or adhesive sheet and an adherend even when the adhesive sheet or adhesive sheet is exposed to a high-temperature and high-humidity environment in a state of being bonded to the adherend.

Drawings

Fig. 1 is a cross-sectional view showing an embodiment of a method for producing a resin film according to the present invention.

Fig. 2 is a cross-sectional view showing an embodiment of an adhesive sheet or the like having a resin film obtained by the production method of the present invention.

Fig. 3 is a cross-sectional view showing another embodiment of an adhesive sheet or the like provided with a resin film obtained by the production method of the present invention.

Fig. 4 is a sectional view showing one use form of an adhesive sheet or the like provided with a resin film obtained by the production method of the present invention.

Description of the reference numerals

1 resin film

1' raw material film

10 pressure-sensitive adhesive sheet

11 12 winding body

13 adhesive sheet or the like (adhesive sheet or adhesive sheet)

21 22, 23, 24 rolls

31 32 protective film

4. Baking oven

41. Warm air blower

51 52 adhesive layer

53 adhesive layer or the like (adhesive layer or adhesive layer)

54 adhesive layer

61 62 release liner

63. Additional resin film

7. Adherends

Detailed Description

[ method for producing resin film ]

The method for producing a resin film of the present invention comprises at least a heating step of heating a raw material film so that the ratio [ the former/the latter ] of the shrinkage ratio of the resin film when heated at a temperature of 120 ℃ for 5 minutes to the expansion ratio when stored at a temperature of 85 ℃ and a humidity of 85% RH for 30 minutes is 0.3 to 2.5. In the present specification, the shrinkage rate when heated at 120 ℃ for 5 minutes may be referred to as "heat shrinkage rate". The expansion ratio when stored for 30 minutes in an environment at a temperature of 85 ℃ and a humidity of 85% rh is sometimes referred to as a "high wet expansion ratio". The method for producing a resin film may include steps other than the heating step.

(heating step)

In the heating step, the raw material film is preferably heated while applying a tensile stress thereto. By heating in this manner, a resin film having the above ratio [ heat shrinkage rate/high wet expansion rate ] in the above range can be easily produced. In particular, by appropriately adjusting the tensile stress according to the type of the raw material film, a resin film having the above ratio [ heat shrinkage rate/high wet expansion rate ] in the above range can be easily produced.

The direction in which the tensile stress is applied is preferably at least one direction, more preferably two directions, and even more preferably two directions orthogonal to each other of the raw material film. Among them, heating is particularly preferable while applying a tensile stress in the MD direction and/or TD direction of the resin film.

The tensile stress may be applied by a known or conventional method. For example, in the heating step, the stretching stress may be applied by stretching in the MD direction and heated. By a method of heating a raw material film while continuously conveying the raw material film using a conveying roller such as a roll-to-roll method, a tensile stress can be applied in the MD direction based on a tensile stress generated during conveyance by the conveying roller. Further, the heating may be performed while applying a tensile stress by stretching such as tenter stretching in the TD direction. Further, the heating may be performed while holding both ends in the MD direction and both ends in the TD direction with a jig or the like and stretching the resultant material to the outside in the MD direction and/or the outside in the TD direction, or may be performed while fixing the material.

The tensile stress is suitably adjusted according to the type and properties of the resin of the raw material film, and is preferably 10N or more, more preferably 30N or more, still more preferably 50N or more, and may be 60N or more, 80N or more, or 100N or more. The tensile stress is preferably 500N or less, more preferably 450N or less, and further preferably 400N or less. When the tensile stress is within the above range, a resin film having the above ratio [ heat shrinkage rate/high wet expansion rate ] within the above range can be easily produced.

When a tensile stress is applied in two directions, the tensile stress in one direction (in particular, MD direction) is preferably 50N or more, more preferably 80N or more, and still more preferably 100N or more. The tensile stress in the one direction (in particular, MD direction) is preferably 500N or less, more preferably 450N or less, and further preferably 400N or less. The tensile stress in the other direction (in particular, TD direction) is preferably 10N or more, more preferably 30N or more, still more preferably 50N or more, and may be 60N or more, 80N or more, or 100N or more. The tensile stress in the other direction (in particular, the TD direction) is preferably 500N or less, more preferably 450N or less, and further preferably 400N or less.

The heating temperature and heating time in the heating step are appropriately selected according to the type of the raw material film. The heating temperature is, for example, 60 to 200 ℃, preferably 80 to 180 ℃, more preferably 100 to 160 ℃. The heating time is, for example, 10 seconds to 30 minutes, preferably 30 seconds to 15 minutes, and more preferably 1 minute to 10 minutes.

The heating may be performed by a known or conventional heating method. Among them, the heating is preferably performed by blowing warm air from at least one surface (preferably both surfaces) of the raw material film. By such a heating method, the raw material thin film can be heated more uniformly.

The heating is preferably performed without laminating other layers such as an adhesive layer and an adhesive layer, and particularly preferably performed as the raw material film itself. In this case, the resin film having the above ratio [ heat shrinkage rate/high wet expansion rate ] in the above range can be easily produced.

The heating is preferably performed while conveying the raw material film. By heating the raw material film while conveying the raw material film, a resin film can be efficiently produced.

(unwinding step)

The production method may further include a step of continuously unwinding the raw material film in the longitudinal direction from a roll around which the raw material film is wound (unwinding step) before the heating step. When the unwinding step is provided, the raw material film can be continuously fed into an oven or the like while being conveyed and heated, and a resin film can be efficiently produced.

(winding Process)

The production method may further include a step of stretching the film after the heating step in the longitudinal direction and winding the film to obtain a roll-shaped resin film blank (winding step). When the winding step is provided, since a tensile stress can be generated in the longitudinal direction (MD direction) of the film at the time of winding, a tensile stress can be easily applied to the raw material film at the time of heating, and the production efficiency is excellent.

Fig. 1 shows an embodiment of a method for producing a resin film according to the present invention. As shown in fig. 1, first, the raw material film 1 'is unwound from the roll 11 around which the raw material film 1' is wound while being nipped by the rolls 21 and 22 (unwinding step). When the protective film 31 is attached to the raw material film 1', the protective film 31 is peeled off by the roller 22 before heating, and the raw material film 1' itself is continuously fed into the oven 4. A plurality of warm air blowers 41 are provided in the oven 4. The raw material film 1' is stretched and conveyed by rollers 23, 24 located outside the outlet of the oven 4. By making the rotational speed of the rollers 23, 24 faster than the rotational speed of the rollers 21, 22, a tensile stress can be applied in the MD direction of the raw material film 1'. Accordingly, both surfaces (upper and lower surfaces) of the raw material film 1 'are heated by the warm air sent from the warm air blower 41 while applying a tensile stress to the raw material film 1' in the oven 4 (heating step). The film fed out from the oven 4 is cooled at room temperature, and the protective film 32 is attached again while being nipped and fed by the rollers 23, 24 and taken up (take-up step). In this way, the roll 12 around which the resin film 1 is wound can be obtained.

(raw material film)

The raw material film is appropriately selected according to the kind of the resin film to be produced. The raw material film may be an unstretched film, or may be a film stretched in at least one direction (stretched film), and is preferably an unstretched film.

The raw material film contains a resin as a main component. The raw material film is formed of a composition containing a resin as a main component. Examples of the resin that can be used for forming a known or conventional film include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homo-polypropylene, polybutene, polymethylpentene, ionomer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-propylene copolymer, cycloolefin resin, ethylene-butene copolymer, and ethylene-hexene copolymer; polyurethane; polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); a polycarbonate resin; polyimide resin; polyether ether ketone; a polyetherimide; polyamides such as aromatic polyamides and wholly aromatic polyamides; polyphenylene sulfide; a fluororesin; polyvinyl chloride; polyvinylidene chloride; cellulose resins such as cellulose Triacetate (TAC); a silicone resin; acrylic resins such as polymethyl methacrylate (PMMA); polysulfone; polyarylate; polyvinyl acetate, and the like. Among them, polycarbonate-based resins, polyester-based resins, acrylic-based resins, cellulose-based resins, and polyolefin-based resins (particularly cycloolefin-based resins) are preferable. The resin may be used alone or in combination of two or more.

The content of the resin in the raw material film is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, or may be 80 mass% or more, 90 mass% or more, or 95 mass% or more, based on the total amount (100 mass%) of the raw material film. The raw material film may contain other components than the resin.

[ resin film ]

The resin film obtained by the production method of the present invention is a resin film in which an adhesive layer or an adhesive layer is laminated (directly laminated) on at least one surface. The resin film is preferably used by laminating (directly laminating) an adhesive layer on at least one surface. The resin film is used as a base material of an adhesive sheet or an adhesive sheet, for example. The resin film is different from a release liner and a base material thereof to be peeled off when the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer are attached to an adherend and used.

Fig. 1 and 2 show an embodiment of a substrate in which the resin film is used as an adhesive sheet. The pressure-sensitive adhesive sheet 10 shown in fig. 2 is a single-sided pressure-sensitive adhesive sheet including the resin film 1 of the present invention and the pressure-sensitive adhesive layer 51 laminated on one side of the resin film 1. The adhesive surface of the adhesive layer 51 is protected by a release liner 61.

The pressure-sensitive adhesive sheet 10 shown in fig. 3 is a double-sided pressure-sensitive adhesive sheet including a resin film 1, a pressure-sensitive adhesive layer 51 laminated on one side of the resin film 1, and a pressure-sensitive adhesive layer 52 laminated on the other side of the resin film 1. The adhesive surface of the adhesive layer 51 is protected by a release liner 61, and the adhesive surface of the adhesive layer 52 is protected by a release liner 62.

The ratio of the shrinkage ratio of the resin film when heated at 120 ℃ for 5 minutes to the expansion ratio when stored at 85 ℃ and 85% RH for 30 minutes [ the former/the latter ] is 0.3 to 2.5.

The ratio [ heat shrinkage/high wet expansion ratio ] is 0.3 or more, preferably 0.4 or more, more preferably 0.5 or more, still more preferably 0.6 or more, particularly preferably 0.7 or more. The above ratio is 2.5 or less, preferably 2.4 or less, more preferably 2.3 or less, still more preferably 2.2 or less, and particularly preferably 2.1 or less. When the ratio is within the above range, the balance between the heat shrinkage and the high wet expansion of the resin film is good, and when the resin film is exposed to a high-temperature and high-humidity environment in a state of being bonded to an adherend via an adhesive layer or an adhesive layer, expansion and shrinkage of the resin film cancel each other, and as a result, dimensional change is less likely to occur, and peeling is less likely to occur between the resin film and the adherend.

The ratio [ heat shrinkage/high wet expansion ratio ] is calculated using the maximum values of the heat shrinkage and the high wet expansion ratio. For example, when the Mechanical (MD) direction value is the largest among the heat shrinkage rates of the resin film and the width (TD) direction value is the largest among the high wet expansion rates of the resin film, the MD direction value is the heat shrinkage rate and the TD direction value is the high wet expansion rate. The heat shrinkage and the high wet expansion are preferably values in directions selected from the MD direction and the TD direction, respectively.

In the present specification, the heat shrinkage X is a positive value, and is calculated as follows: the distance between the evaluation points before heating (at room temperature) was defined as a, and the distance between the evaluation points after heating at 120 ℃ for 5 minutes was defined as a', where the positions of the two sides of the rectangular or square resin film facing each other were defined as 2 evaluation points at arbitrary distances from the respective midpoints toward the center, and the distance was calculated by the following formula (1).

X[％]＝(a-a’)/a×100 (1)

In the present specification, the high wet expansion ratio Y is a positive value, and is calculated as follows: the distance between the evaluation points before heating (at room temperature) was defined as a, and the distance between the evaluation points after storage in an environment at a temperature of 85 ℃ and a humidity of 85% rh for 30 minutes was defined as a' when the positions of the two sides of the rectangular or square resin film facing each other were defined as 2 evaluation points at arbitrary distances from the respective midpoints toward the center.

Y[％]＝(a’-a)/a×100 (2)

The resin film contains a resin as a main component. The resin film is formed from a composition containing a resin as a main component. Examples of the resin film include various optical films such as plastic films, antireflection (AR) films, antiglare (AG) films, polarizing plates, and retardation plates, porous materials such as cloths and nonwoven fabrics, nets, foamed sheets, and the like. The film may be a porous film or a nonporous film.

The resin may be any known or conventionally used resin for forming a film, and examples thereof include resins exemplified and described as the resin that can be contained in the raw material film. Among them, polycarbonate-based resins, polyester-based resins, acrylic-based resins, cellulose-based resins, and polyolefin-based resins (particularly cycloolefin-based resins) are preferable. The resin may be used alone or in combination of two or more.

The content of the resin in the resin film is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, or may be 80 mass% or more, 90 mass% or more, or 95 mass% or more, based on the total amount (100 mass%) of the resin film. The resin film may contain other components than the resin.

The saturated water absorption rate of the resin film is preferably 2.0% or less, more preferably less than 1.5%, further preferably less than 1.1%, further preferably 1.0% or less, and particularly preferably 0.8% or less. When the saturated water absorption is 2.0% or less, peeling is less likely to occur between the adhesive layer and the adherend when the adhesive layer is exposed to a high-temperature and high-humidity environment in a state of being bonded to the adherend via the adhesive layer or the adhesive layer. The saturated water absorption can be determined based on JIS K7209.

The thickness of the resin film is not particularly limited, but is preferably 10 to 1000. Mu.m, more preferably 50 to 800. Mu.m, and still more preferably 70 to 500. Mu.m.

At least one surface of the resin film may be subjected to physical treatments such as corona discharge treatment, plasma treatment, sand mat treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, and ionizing radiation treatment for the purpose of improving adhesion to an adhesive layer or an adhesive layer, retaining property, and the like; chemical treatments such as chromic acid treatment; surface treatment such as easy adhesion treatment by a coating agent (primer). The surface treatment for improving the adhesion is preferably performed on the entire surface of the resin film on the side of the laminated adhesive layer or the adhesive layer.

The resin film is preferably used by laminating another resin film with an adhesive layer or an adhesive layer.

The ratio [ former/latter ] of the high wet expansion ratio of the resin film to the shrinkage ratio when the other resin film is stored for 30 minutes at a temperature of 85 ℃ and a humidity of 85% rh is preferably 0.5 or more, more preferably 0.9 or more, and still more preferably 1.0 or more. The above ratio is preferably 3.5 or less, more preferably 3.0 or less, and still more preferably 2.0 or less. The shrinkage of the other resin film when stored in an environment with a humidity of 85% rh for 30 minutes is sometimes referred to as "high wet shrinkage". If the ratio is within the above range, the balance between expansion and contraction of the resin film can be obtained when the resin film is stored in an environment of 85% RH for 30 minutes, and therefore peeling is less likely to occur between the resin film, the adhesive layer or the adhesive layer, and the other layers of the resin film.

The high wet shrinkage is not particularly limited, but is preferably 1.0% or less (e.g., 0 to 1.0%), more preferably 0.5% or less, and still more preferably 0.2% or less. In the present specification, the high wet shrinkage Z is calculated as follows: the distance between the evaluation points before heating (at room temperature) was defined as b, and the distance between the evaluation points after storage in an environment at a temperature of 85 ℃ and a humidity of 85% rh for 30 minutes was defined as b' when the positions of the two sides of the rectangular or square resin film facing each other were defined as 2 evaluation points at arbitrary distances from the respective midpoints toward the center, and the distance was calculated by the following formula (3). The high wet shrinkage rate described above was the maximum value. The high wet shrinkage is preferably a value in a direction selected from the MD direction and the TD direction.

Z[％]＝(b-b’)/b×100 (3)

The above-mentioned other resin film contains a resin as a main component. The other resin film is formed of a composition containing a resin as a main component. Examples of the other resin film include various optical films such as plastic films, antireflection (AR) films, antiglare (AG) films, polarizing plates, and retardation plates, porous materials such as cloths and nonwoven fabrics, nets, and foamed sheets. The film may be a porous film or a nonporous film.

The resin may be any known or conventionally used resin for forming a thin film, and examples thereof include the resins exemplified and described above as the resins constituting the raw material thin film. The content of the resin in the other resin film is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, or may be 80 mass% or more, 90 mass% or more, or 95 mass% or more, based on the total amount (100 mass%) of the other resin film. The resin film may contain other components than the resin.

When the resin film is used by laminating another resin film on one surface via an adhesive layer or an adhesive layer, the other surface is preferably laminated with (formed with) an adhesive layer or an adhesive layer (particularly an adhesive layer). In this case, the resin film may be bonded to the adherend with the other surface laminated with the other resin film.

[ adhesive layer or adhesive layer ]

In this specification, the pressure-sensitive adhesive layer or the adhesive layer is sometimes referred to as "pressure-sensitive adhesive layer or the like". In addition, in the present specification, "adhesion" means that the following properties are involved: by the pressure from the outside (for example, a minute pressure), the composition has a property that 2 surfaces are sealed based on cohesive force due to a chemical structure, and can be peeled off as needed. In contrast, "adhesion" refers to the following properties: the composition was chemically reacted (cured) to give a cured product, and the 2 surfaces were firmly bonded without peeling. In the present specification, the "adhesive layer" is a layer-shaped adhesive layer having no fluidity, and the "adhesive layer" is a layer-shaped adhesive layer having no fluidity.

Examples of the pressure-sensitive adhesive layer include a pressure-sensitive adhesive layer containing a polymer capable of exhibiting pressure-sensitive adhesive properties and/or adhesiveness. The polymer may be contained in one kind or two or more kinds. Examples of the polymer include thermoplastic resins, thermosetting resins, and active energy ray-curable resins. The adhesive layer containing a thermoplastic resin can exhibit adhesion by, for example, pressure from the outside. The pressure-sensitive adhesive layer or the like containing the thermosetting resin can be bonded to an adherend by, for example, curing by heating.

The thermosetting resin includes both a resin having thermosetting properties (thermosetting resin) and a resin obtained by curing the thermosetting resin. The thermosetting resin has a thermosetting functional group. The number of thermosetting functional groups in the thermosetting resin is preferably 2 or more (for example, 2 to 4). Examples of the thermosetting resin include phenolic resins, epoxy resins, urethane resins, melamine resins, alkyd resins, and silicone resins.

Examples of the thermoplastic resin include polystyrene resin, vinyl acetate resin, polyester resin, polyolefin resin (polyethylene resin, polypropylene resin composition, etc.), polyimide resin, acrylic resin, rubber (natural rubber, synthetic rubber, a mixture thereof, etc.), polyether resin, polyamide resin, fluorine resin, etc. Among them, acrylic resins are preferable because cohesive force and moderate flexibility can be imparted to the adhesive layer or the like.

The pressure-sensitive adhesive layer and the like preferably contain an acrylic resin as a base polymer. In the present specification, the base polymer means a main component of a polymer component in an adhesive or an adhesive constituting an adhesive layer, for example, a polymer component in an amount exceeding 50 mass%. The content of the base polymer in the pressure-sensitive adhesive layer or the like is preferably 60 mass% or more, more preferably 70 mass% or more, relative to 100 mass% of the total amount of the pressure-sensitive adhesive layer or the like.

The acrylic resin is designed in various ways according to the purpose, and it is preferable to appropriately select the monomer type, copolymerization composition ratio, molecular weight distribution, crosslinking agent, compounding composition ratio, and the like, according to the target values of specific characteristic values such as mechanical properties such as flexibility and elastic modulus, thermal properties such as glass transition temperature, adhesive force and adhesion force, and the like.

The acrylic resin is a resin containing an acrylic monomer (a monomer having a (meth) acryloyl group in a molecule) as a monomer component constituting the resin. That is, the acrylic resin contains a constituent unit derived from an acrylic monomer. The acrylic resin is preferably a polymer containing an alkyl (meth) acrylate as a monomer component constituting the polymer. In the present specification, "(meth) acrylic acid" means "acrylic acid" and/or "methacrylic acid" ("acrylic acid" or "methacrylic acid" either or both), and the other is the same.

The acrylic resin is preferably a polymer containing the largest amount of constituent units derived from (meth) acrylic esters in terms of mass ratio. Examples of the (meth) acrylate include hydrocarbon group-containing (meth) acrylates. Examples of the hydrocarbon group-containing (meth) acrylate include (meth) acrylic acid esters having an alicyclic hydrocarbon group such as alkyl (meth) acrylate and cycloalkyl (meth) acrylate having a linear or branched aliphatic hydrocarbon group, and (meth) acrylic acid esters having an aromatic hydrocarbon group such as aryl (meth) acrylate. The hydrocarbon group-containing (meth) acrylate may be used alone or in combination of two or more.

Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, and nonadecyl (meth) acrylate.

The alkyl (meth) acrylate is particularly preferably an alkyl (meth) acrylate having a linear or branched aliphatic hydrocarbon group having 1 to 20 carbon atoms (preferably 2 to 12 carbon atoms, more preferably 4 to 10 carbon atoms). When the carbon number is within the above range, the glass transition temperature of the acrylic resin can be easily adjusted, and the adhesion can be easily made more suitable.

Examples of the (meth) acrylic acid ester having an alicyclic hydrocarbon group include (meth) acrylic acid esters having an alicyclic hydrocarbon ring such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate; (meth) acrylic esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth) acrylate; and (meth) acrylic esters having an aliphatic hydrocarbon ring having three or more rings, such as dicyclopentyloxy ethyl (meth) acrylate, tricyclopentyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate.

Examples of the (meth) acrylic acid ester having an aromatic hydrocarbon group include phenyl (meth) acrylate and benzyl (meth) acrylate.

In order to suitably exhibit basic properties such as adhesiveness due to the hydrocarbon group-containing (meth) acrylate, the proportion of the hydrocarbon group-containing (meth) acrylate in the total monomer components constituting the acrylic resin is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more, relative to the total amount (100% by mass) of the total monomer components. The ratio may be 99.9 mass% or less, or 98 mass% or less, 95 mass% or less, 90 mass% or less, or 80 mass% or less, from the viewpoint of the effect of the other monomer component obtained by copolymerizing the monomer component with the other monomer component.

The acrylic resin may contain a constituent unit derived from another monomer component copolymerizable with the hydrocarbon group-containing (meth) acrylate for the purpose of improving cohesive force, introducing crosslinking points, and the like. Examples of the other monomer component include a polar group-containing monomer such as a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, a carboxyl group-containing monomer, an acid anhydride monomer, a ketone group-containing monomer, an alkoxysilyl group-containing monomer, a glycidyl group-containing monomer, a sulfonic acid group-containing monomer, and a phosphoric acid group-containing monomer. The other monomer components may be used singly or in combination of two or more.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate.

Examples of the nitrogen atom-containing monomer include an amide group-containing monomer, an amino group-containing monomer, a cyano group-containing monomer, and a monomer having a nitrogen atom-containing ring. Examples of the amide group-containing monomer include (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxymethyl propane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide. Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and the like. Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile. Examples of the monomer having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methyl-vinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyridine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N- (meth) acryloylmorpholine and the like.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride.

Examples of the ketone group-containing monomer include diacetone (meth) acrylamide, diacetone (meth) acrylate, vinylmethyl ketone, vinylethyl ketone, allyl acetoacetate, and vinyl acetoacetate.

Examples of the alkoxysilyl group-containing monomer include 3- (meth) acryloxypropyl trimethoxysilane, 3- (meth) acryloxypropyl triethoxysilane, 3- (meth) acryloxypropyl methyldimethoxysilane, and 3- (meth) acryloxypropyl methyldiethoxysilane.

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloxynaphthalene sulfonic acid.

Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

The total of the proportions of the polar group-containing monomers in the total monomer components (100 mass%) constituting the acrylic resin is not particularly limited, but is preferably 0.1 mass% or more, more preferably 1 mass% or more, still more preferably 5 mass% or more, and may be 10 mass% or more, 15 mass% or more, 20 mass% or more, or 25 mass% or more, from the viewpoint of better effects due to the use of the polar group-containing monomers. The total of the above proportions is preferably 50 mass% or less, more preferably 40 mass% or less, from the viewpoint of obtaining an adhesive layer having moderate flexibility.

The monomer component constituting the acrylic resin may further contain other monomers. Examples of the other monomer include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α -methylstyrene, etc.), and vinyl toluene; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether.

The proportion of the other monomer may be, for example, 0.05 mass% or more and 0.5 mass% or more, based on 100 mass% of the total amount of all the monomer components constituting the acrylic resin. The proportion may be, for example, 20 mass% or less, 10 mass% or less, or 5 mass% or less, or may be substantially not contained.

The acrylic resin is obtained by polymerizing a monomer component containing the acrylic monomer. The polymerization method is not particularly limited, and examples thereof include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a thermal polymerization method, a polymerization method by irradiation of active energy rays (active energy ray polymerization method), and the like. Among them, bulk polymerization, thermal polymerization, and active energy ray polymerization are preferable from the viewpoints of transparency of an adhesive layer and the like, cost, and the like. The acrylic resin may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

In the polymerization of the monomer component, various general solvents can be used. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; organic solvents such as ketones including methyl ethyl ketone and methyl isobutyl ketone. The solvent may be used alone or in combination of two or more.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization of the monomer component are not particularly limited, and may be suitably selected and used. The weight average molecular weight of the acrylic resin may be controlled by the amount of the polymerization initiator, the amount of the chain transfer agent, and the reaction conditions, and the amount thereof may be appropriately adjusted depending on the kind of the polymerization initiator, the chain transfer agent, and the reaction conditions.

As the polymerization initiator used in the polymerization of the monomer component, a thermal polymerization initiator, a photopolymerization initiator (photoinitiator), or the like can be used depending on the kind of polymerization reaction. The polymerization initiator may be used alone or in combination of two or more.

The thermal polymerization initiator is not particularly limited, and examples thereof include azo polymerization initiators, peroxide polymerization initiators (e.g., dibenzoyl peroxide, t-butyl peroxymaleate, persulfates such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, etc.), substituted ethane initiators such as phenyl-substituted ethane, aromatic carbonyl compounds, redox polymerization initiators, and the like. Among them, the azo-based polymerization initiator disclosed in Japanese patent application laid-open No. 2002-69411 is preferable. Examples of the azo-based polymerization initiator include 2,2 '-azobisisobutyronitrile, 2' -azobis-2-methylbutyronitrile, dimethyl 2,2 '-azobis (2-methylpropionate), and 4,4' -azobis-4-cyanovaleric acid. The amount of the thermal polymerization initiator to be used may be a usual amount, and may be selected from, for example, 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the monomer component.

As the above-mentioned photopolymerizationThe synthetic initiator is not particularly limited, and examples thereof include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α -ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzil-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like. Further, an acylphosphine oxide-based photopolymerization initiator and a titanocene-based photopolymerization initiator may be mentioned. Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-dimethoxy-1, 2-diphenylethane-1-one, anisole methyl ether, and the like. Examples of the acetophenone photopolymerization initiator include 2, 2-diethoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl) dichloroacetophenone. Examples of the α -ketol photopolymerization initiator include 2-methyl-2-hydroxyphenylacetone and 1- [4- (2-hydroxyethyl) phenyl ] ]-2-methylpropan-1-one and the like. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photo-polymerization initiator include 1-phenyl-1, 1-propanedione-2- (O-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzil photopolymerization initiator include benzil. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoyl benzoic acid, 3' -dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α -hydroxycyclohexyl phenyl ketone. Examples of the ketal photopolymerization initiator include benzildimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the acylphosphine oxide photopolymerization initiator includeExamples thereof include 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide and bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide. Examples of the titanocene-based photopolymerization initiator include bis (. Eta.. Eta.) ⁵ -2, 4-cyclopentadien-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) -titanium and the like. The amount of the photopolymerization initiator to be used may be a usual amount, and may be selected from, for example, 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the monomer component.

The pressure-sensitive adhesive layer and the like may contain other components than the above components as needed. Examples of the other components include a curing catalyst, a crosslinking agent (including polyfunctional (meth) acrylate), a crosslinking accelerator, a polymerization initiator, a tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), an oligomer, an antioxidant, a filler (metal powder, organic filler, inorganic filler, etc.), a colorant (pigment, dye, etc.), an antioxidant, a plasticizer, a softener, a surfactant, an antistatic agent, a surface lubricant, a leveling agent, a light stabilizer, an ultraviolet absorber, a sensitizer, a polymerization inhibitor, a particulate matter, a foil, a flame retardant, a silane coupling agent, an ion scavenger, and the like. The other components may be used alone or in combination of two or more.

The crosslinking agent is not particularly limited as long as it is a substance that crosslinks a polymer, and examples thereof include a polyisocyanate compound, an epoxy compound, a polyol compound (a polyhydric phenol compound and the like), an aziridine compound, a melamine-based crosslinking agent, a polyfunctional (meth) acrylate and the like. Examples of the polyfunctional (meth) acrylate include (meth) acrylates having 2 or more functions, for example, 1, 6-hexanediol diacrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. The crosslinking agent may be used alone or in combination of two or more.

The silane coupling agent is not particularly limited, and examples thereof include gamma-glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, and N-phenyl-aminopropyl trimethoxysilane. The silane coupling agent may be used alone or in combination of two or more.

As the colorant, a black-based colorant is preferable. The black-based colorant may be any known or customary colorant (pigment, dye, etc.) for exhibiting black color, and examples thereof include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine black, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (nonmagnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, anthraquinone-based colorant, zirconium nitride, etc. Further, a colorant that is combined and mixed to exhibit a color other than black may be used and functions as a black-based colorant.

When the pressure-sensitive adhesive layer and the like contain a colorant, the content of the colorant in the pressure-sensitive adhesive layer and the like is preferably 0.2 mass% or more, more preferably 0.4 mass% or more, relative to 100 mass% of the total amount of the pressure-sensitive adhesive layer and the like. The content of the colorant is, for example, 10 mass% or less, preferably 5 mass% or less, and more preferably 3 mass% or less. The content ratio may be appropriately set according to the type of the colorant and the desired properties.

The thickness of the pressure-sensitive adhesive layer or the like (the total thickness of the pressure-sensitive adhesive layer or the like on one side) is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. When the thickness is 10 μm or more, the adhesive force to an adherend is more excellent. The thickness of the pressure-sensitive adhesive layer is, for example, 500 μm or less, preferably 300 μm or less. When the thickness is 500 μm or less, the thickness of the pressure-sensitive adhesive sheet or the like can be made thinner. The thickness of the adhesive layers and the like on the two sides may be the same or different.

The pressure-sensitive adhesive layer may be in any form, and may be, for example, emulsion type, solvent type (solution type), active energy ray-curable type, hot-melt type (hot-melt type), or the like. Among them, solvent-based and active energy ray-curable adhesive layers are preferable from the viewpoint of easy availability of adhesive layers and the like excellent in productivity.

Examples of the active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron beams, and electron beams, ultraviolet rays, and the like, and ultraviolet rays are particularly preferred. That is, the active energy ray-curable adhesive layer and the like are preferably an ultraviolet-curable adhesive layer and the like.

The adhesive layer and the like can be produced, for example, as follows: applying (coating) an adhesive composition or an adhesive composition for forming an adhesive layer or the like onto a release liner, and drying and curing the resulting adhesive composition layer or adhesive composition layer; the adhesive composition or the adhesive composition is coated (applied) on a release liner, and the adhesive composition layer or the adhesive composition layer thus obtained is cured by irradiation with active energy rays. Further, if necessary, the heat drying may be further performed.

[ pressure-sensitive adhesive sheet and pressure-sensitive adhesive sheet ]

The adhesive sheet or the adhesive sheet can be produced using the above resin film as a base material. In this specification, an adhesive sheet or an adhesive sheet is sometimes referred to as "adhesive sheet or the like". In addition, when referred to as "adhesive sheet" in the present specification, the term "adhesive tape" is also included as a strip-like substance, and the same applies to "adhesive sheet". The pressure-sensitive adhesive sheet may be a double-sided pressure-sensitive adhesive sheet having both sides of the surface of the pressure-sensitive adhesive layer or the like, or may be a single-sided pressure-sensitive adhesive sheet having only one side of the surface of the pressure-sensitive adhesive layer or the like.

The adhesive sheet and the like are adhesive sheets and the like comprising the resin film as a base material and an adhesive layer and the like formed on at least one surface of the base material. The "substrate (substrate layer)" refers to a support, and is a portion that is attached to an adherend together with an adhesive layer or the like when the adhesive sheet or the like is used (attached) to the adherend. The release liner that is peeled off at the time of use (attachment) of the adhesive sheet or the like is not included in the above-described base material.

The pressure-sensitive adhesive sheet and the like are single-sided pressure-sensitive adhesive sheets and the pressure-sensitive adhesive layer and the like may be provided as either a pressure-sensitive adhesive layer or an adhesive layer, and is preferably an adhesive layer.

In the case where the pressure-sensitive adhesive sheet or the like is a double-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layers or the like provided on the both sides of the base material may be both pressure-sensitive adhesive layers, both pressure-sensitive adhesive layers may be pressure-sensitive adhesive layers, one of the pressure-sensitive adhesive layers and the other pressure-sensitive adhesive layer may be pressure-sensitive adhesive layers, and preferably at least one of the pressure-sensitive adhesive layers is pressure-sensitive adhesive layer. The pressure-sensitive adhesive layers and the like provided on both surfaces of the base material in the pressure-sensitive adhesive sheet and the like may be the same pressure-sensitive adhesive layers and the like, or may be pressure-sensitive adhesive layers and the like having different compositions, thicknesses, physical properties and the like. The pressure-sensitive adhesive layers and the like provided on both surfaces of the substrate may be single layers or may be multiple layers composed of the same layer or layers having different compositions, thicknesses, physical properties, and the like.

The thickness of the pressure-sensitive adhesive sheet is preferably 100 to 1500. Mu.m, more preferably 120 to 1200. Mu.m, and still more preferably 150 to 1000. Mu.m. The thickness of the adhesive sheet or the like refers to the thickness from the adhesive surface or the bonding surface to the exposed surface of the base material in the case of a single-sided adhesive sheet or the like, and refers to the thickness from one adhesive surface or the bonding surface to the other adhesive surface or the bonding surface in the case of a double-sided adhesive sheet or the like, that is, the thickness of the adherend or the adherend, excluding the release liner.

The pressure-sensitive adhesive sheet and the like may be provided with a release liner on the surface (pressure-sensitive adhesive surface or bonding surface) of the pressure-sensitive adhesive layer and the like until the time of use. The adhesive surfaces or the adhesive surfaces in the case where the adhesive sheet or the like is a double-sided adhesive sheet may be each protected with 2 release liners, or may be protected in a roll form (roll) by using 1 release liner having both sides as release surfaces. The release liner is used as a protective material for an adhesive layer or the like, and is peeled off when attached to an adherend. It should be noted that a release liner may not be necessary.

Examples of the base material of the release liner include polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate film, ionomer resin film, ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, and fluororesin film. Further, crosslinked films thereof can be exemplified. Further, they may be laminated films.

The release surface of the release liner (particularly, the surface in contact with the adhesive layer or the like) is preferably subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

The thickness of the release liner is not particularly limited, and is, for example, about 20 to 150 μm.

The adherend to be bonded with the adhesive sheet and the like is not particularly limited, and examples thereof include the other resin films. In the case where the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, the adherend to be bonded to one side may be the other resin film, and the other side may be bonded to the other adherend.

Fig. 4 shows an embodiment in which the adhesive sheet or the like is bonded to an adherend. The adhesive sheet or the like 13 shown in fig. 4 includes a resin film 1, an adhesive layer or the like (adhesive layer or adhesive layer) 53 formed on one surface of the resin film 1, and an adhesive layer 54 formed on the other surface of the resin film 1. A separate resin film 63 is bonded to the pressure-sensitive adhesive layer 53 or the like. The pressure-sensitive adhesive layer 54 side of the pressure-sensitive adhesive sheet 13 to which the other resin film 63 is attached to the adherend 7. Thereby, the other resin film 63 is fixed to the adherend 7 via the adhesive sheet or the like 13. When the resin film 1 is used as a base material of the adhesive sheet or the like 13, peeling is less likely to occur between the other resin film 63 and the adhesive layer or the like 53, between the resin film 1 and the adhesive layer or the like 53, and between the resin film 1 and the adhesive layer 54 when exposed to a high-temperature and high-humidity environment in the state shown in fig. 4.

The application of the pressure-sensitive adhesive sheet and the like is not particularly limited, and the pressure-sensitive adhesive sheet and the like can be used for any application. For example, the adhesive composition can be used for optical applications, that is, applications to be bonded to an optical member. By using the adhesive sheet or the like for optical applications, reliability is excellent. For example, the other resin film as an adherend may be laminated on one surface of the pressure-sensitive adhesive sheet or the like with an adhesive layer or the like, and the other surface may be bonded to another adherend such as a glass substrate with an adhesive layer or the like.

The pressure-sensitive adhesive sheet and the like are used, for example, when various members or components are mounted (assembled) in predetermined positions (for example, a case, a front panel, a window portion, and the like) in optical members such as electric and electronic devices. The term "electric and electronic device" refers to a device that belongs to at least one of an electric device and an electronic device. Examples of the electric and electronic devices include liquid crystal displays, organic/inorganic electroluminescent displays, image display devices such as plasma displays, and portable electronic devices. Examples of the image display device include an image display device in the portable electronic device, a vehicle-mounted display, a digital signage (electronic billboard or electronic bulletin board), and the like. The image display device may be in a form (structure) such as a so-called "rigid type" or a so-called "flexible type", or may be in a form (structure) such as a so-called "foldable type" or a so-called "crimpable type" that can be folded.

Examples of the portable electronic device include a cellular phone, a smart phone, a tablet personal computer, a notebook personal computer, various wearable devices (for example, a wrist-worn type such as a wristwatch, a modularized type worn on a part of the body with a clip, a band, or the like, a eyewear type (eye-worn type) including a glasses type (monocular type, binocular type, helmet type, or the like), a clothing type mounted on a shirt, a sock, a hat, or the like, an ear-worn type mounted on an ear such as an earphone, or the like, in the form of a decorative article), a digital camera, a digital video camera, an audio device (portable music player, a recording pen, or the like), a calculator (desktop calculator, or the like), a portable game device, an electronic dictionary, an electronic organizer, an electronic book, a vehicle-mounted information device, a portable radio, a portable television, a portable printer, a portable scanner, a portable modem, or the like. In this specification, "portable" is interpreted as being insufficient in that it can be carried only, and means that it has a level of portability that an individual (a standard adult) can relatively easily carry.

Examples

The following examples illustrate the invention in more detail, but the invention is not limited to these examples.

Production example 1

[ preparation of adhesive (1) ]

(preparation of acrylic prepolymer solution A)

Into a separable flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen inlet tube, 78 parts by mass of 2-ethylhexyl acrylate (2-EHA), 18 parts by mass of N-vinyl-2-pyrrolidone (NVP), 5 parts by mass of 2-hydroxyethyl acrylate (HEA), 0.035 parts by mass of a photopolymerization initiator (trade name "omnirad 184", manufactured by IGM Resins Italia Srl company), and 0.035 parts by mass of a photopolymerization initiator (trade name "omnirad 651", manufactured by IGM Resins Italia Srl company) were charged, and nitrogen was circulated while stirring for about 1 hour. Thereafter, at 5mW/cm ² The polymerization was carried out by irradiation with ultraviolet rays, and the reaction rate was adjusted to 5 to 15%, thereby obtaining an acrylic prepolymer solution a.

(preparation of acrylic oligomer solution)

100 parts by mass of toluene, 60 parts by mass of dicyclohexyl methacrylate (DCPMA) (trade name "FA-513M", manufactured by Hitachi chemical industry Co., ltd.), 40 parts by mass of Methyl Methacrylate (MMA), and 3.5 parts by mass of alpha-thioglycerol as a chain transfer agent were charged into a four-necked flask. Then, after stirring at 70℃for 1 hour under a nitrogen atmosphere, 0.2 parts by mass of AIBN as a thermal polymerization initiator was charged, and reacted at 70℃for 2 hours, followed by reaction at 80℃for 2 hours. Thereafter, the reaction solution was put into a temperature atmosphere of 130 ℃, and toluene, a chain transfer agent and an unreacted monomer were dried and removed, whereby a solid acrylic oligomer was obtained. The Tg of the acrylic oligomer was 144℃and the Mw was 4300. 50 parts by mass of 2-ethylhexyl acrylate (2-EHA) was added to 50 parts by mass of the above-mentioned acrylic oligomer, and the mixture was dissolved to obtain an acrylic oligomer solution.

(preparation of adhesive (1))

17.6 parts by mass of 2-hydroxyethyl acrylate (HEA), 11.8 parts by mass of an acrylic oligomer solution, 0.088 parts by mass of a 2-functional monomer (trade name "NK ESTR A-HD-N", manufactured by Xinzhou Chemie Co., ltd.) and 0.353 parts by mass of a silane coupling agent (trade name "KBM-403", manufactured by Xinyue chemical Co., ltd., 3-glycidoxypropyl trimethoxysilane) were added to the acrylic prepolymer solution A (total amount: 100 parts by mass), to obtain a binder (1).

Production example 2

[ preparation of adhesive (2) ]

(preparation of acrylic prepolymer solution B)

67 parts by mass of Butyl Acrylate (BA), 14 parts by mass of cyclohexyl acrylate (CHA), 19 parts by mass of 4-hydroxybutyl acrylate (4-BHA), 0.09 parts by mass of a photopolymerization initiator (trade name "omnirad 184", manufactured by IGM Resins Italia Srl Co.) and 0.09 parts by mass of a photopolymerization initiator (trade name "omnirad 651", manufactured by IGM Resins Italia Srl Co.) were put into a separable flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen inlet pipe, and nitrogen was introduced thereinto, followed by stirring and nitrogen substitution for about 1 hour. Thereafter, at 5mW/cm ² The polymerization was carried out by irradiation with ultraviolet rays, and the reaction rate was adjusted to 5 to 15%, thereby obtaining an acrylic prepolymer solution B.

(preparation of adhesive (2))

To the acrylic prepolymer solution B (total 100 parts by mass), 9 parts by mass of 2-hydroxyethyl acrylate (HEA), 8 parts by mass of 4-hydroxybutyl acrylate (4-HBA), 0.1 part by mass of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", manufactured by Xinzhou Chemie Co., ltd.) as a polyfunctional monomer, and 0.4 part by mass of a silane coupling agent (trade name "KBM-403", manufactured by Xinyue Chemie Co., ltd., 3-glycidoxypropyl trimethoxysilane) were added to obtain a binder (2).

Example 1

(production of resin film)

A polycarbonate resin film material (saturated water absorption: 1.5%) having a thickness of 180 μm was produced by vacuum drying under the trade name "DURABIO" (manufactured by Mitsubishi chemical corporation, polycarbonate resin) at 80℃for 5 hours and then using a film-forming apparatus comprising a single screw extruder (manufactured by Mitsubishi mechanical Co., ltd., drum set temperature: 250 ℃), a T die (width: 300mm, set temperature: 250 ℃), a cooling roll (set temperature: 120 to 130 ℃) and a winding machine.

The polycarbonate resin film of example 1 (thickness 179 μm, saturated water absorption 1.5%) was produced by heating the polycarbonate resin film blank at 120℃for 5 minutes while applying a tensile stress of 60N in the MD direction without applying a tensile stress in the TD direction.

(production of double-sided adhesive sheet)

The adhesive (1) was applied to a release liner (trade name "MRF#38", manufactured by Mitsubishi chemical Co., ltd.) having a thickness of 38 μm and having a release surface on one side of the polyester film, and the film was irradiated with a black light until the cumulative light amount was 3600mJ/cm ² Polymerizing it. After the irradiation, the coated surface was covered with a release liner (trade name "MRE#38", manufactured by Mitsubishi chemical corporation) having a thickness of 38 μm, which was a release surface of one side of the polyester film, to thereby produce an adhesive layer (1) having a thickness of 25 μm.

The adhesive (2) was applied to a release liner (trade name "MRF#38", manufactured by Mitsubishi chemical Co., ltd.) having a thickness of 38 μm and having a release surface on one side of the polyester film, and the film was irradiated with a black light until the cumulative light amount was 3600mJ/cm ² Polymerizing it. After the irradiation, the coated surface was covered with a release liner (trade name "MRE#38", manufactured by Mitsubishi chemical corporation) having a thickness of 38 μm, which was a release surface of one side of the polyester film, to thereby prepare an adhesive layer (2) having a thickness of 100. Mu.m.

The adhesive layer (1) is bonded to one surface of the polycarbonate resin film, and the adhesive layer (2) is bonded to the other surface. Thus, a double-sided pressure-sensitive adhesive sheet was produced in which pressure-sensitive adhesive layers (1) and (2) were laminated on both sides of a polycarbonate resin film, and further release liners were laminated on both pressure-sensitive adhesive layers.

Example 2

(production of resin film)

The polycarbonate resin film blank produced in example 1 was subjected to a tensile stress of 60N in the MD direction and a tensile stress of 60N on both sides in the TD direction, and was heated at 120 ℃ for 5 minutes to produce a polycarbonate resin film of example 2 (thickness 177 μm, saturated water absorption: 1.5%).

(production of double-sided adhesive sheet)

A double-sided adhesive sheet was produced in the same manner as in example 1, except that the polycarbonate resin film of example 2 was used instead of the polycarbonate resin film of example 1.

Example 3

(production of resin film)

The polycarbonate resin film blank produced in example 1 was subjected to a tensile stress of 390N in the MD direction and a tensile stress of 450N also in both sides in the TD direction, and was heated at 120 ℃ for 5 minutes to produce a polycarbonate resin film of example 3 (thickness 170 μm, saturated water absorption 1.5%).

(production of double-sided adhesive sheet)

A double-sided adhesive sheet was produced in the same manner as in example 1, except that the polycarbonate resin film of example 3 was used instead of the polycarbonate resin film of example 1.

Example 4

(production of resin film)

The polyester resin film of example 4 (thickness 186 μm, saturated water absorption 0.7%) was produced by heating a polyester resin film blank (trade name "Diafoil S100", mitsubishi chemical corporation, thickness 188 μm) at 120℃for 5 minutes while applying a tensile stress to both sides in the TD direction without applying a tensile stress in the MD direction.

(production of double-sided adhesive sheet)

A double-sided adhesive sheet was produced in the same manner as in example 1, except that the polyester-based resin film of example 4 was used instead of the polycarbonate resin film of example 1.

Comparative example 1

(production of double-sided adhesive sheet)

A double-sided adhesive sheet was produced in the same manner as in example 1, except that the polycarbonate resin film blank produced in example 1 was used instead of the polycarbonate resin film of example 1.

Comparative example 2

(production of resin film)

The polycarbonate resin film blank produced in example 1 was heated at 120℃for 5 minutes without applying tensile stress in both the MD and TD directions, to produce a polycarbonate resin film of comparative example 2 (thickness 183 μm, saturated water absorption: 1.5%).

(production of double-sided adhesive sheet)

A double-sided adhesive sheet was produced in the same manner as in example 1, except that the polycarbonate resin film of comparative example 2 was used instead of the polycarbonate resin film of example 1.

Comparative example 3

(production of resin film)

The polycarbonate resin film blank produced in example 1 was subjected to a tensile stress of 390N in the MD direction and a tensile stress of 600N also in both sides in the TD direction, and was heated at 120 ℃ for 5 minutes to produce a polycarbonate resin film of comparative example 3 (thickness 166 μm, saturated water absorption 1.5%).

(production of double-sided adhesive sheet)

A double-sided adhesive sheet was produced in the same manner as in example 1, except that the polycarbonate resin film of comparative example 3 was used instead of the polycarbonate resin film of example 1.

Comparative example 4

(production of double-sided adhesive sheet)

A double-sided pressure-sensitive adhesive sheet was produced in the same manner as in example 1, except that a polyester resin film blank (trade name "diafile S100", manufactured by mitsubishi chemical co., ltd., saturated water absorption 0.7%) was used instead of the polycarbonate resin film of example 1.

< evaluation >

The resin films and the double-sided adhesive sheets obtained in examples and comparative examples were evaluated as follows. The results are shown in the table.

(1) Heat shrinkage and high wet expansion

For the resin film, test pieces of 100mm×100mm were cut, and evaluation points were set at positions 20mm toward the center from the midpoints of the 4 sides. The evaluation point-to-point distance a between the facing points was measured at a room temperature environment of 25℃and 50% RH. Then, the heat shrinkage was put into an environmental tester set at a temperature of 120℃for 5 minutes. For high wet expansion, the mixture was put into an environmental tester set at a temperature of 85℃and a humidity of 85% RH for 30 minutes. Thereafter, the test piece was taken out of the environmental tester to the same environment as before being put into the environmental tester, that is, to a room temperature environment having a temperature of 25℃and a humidity of 50% RH, and then the distance a' between the evaluation points was measured by planar biaxial dimensions measurement (trade name "QVA 1517-PRO_AE 1M (SP)", manufactured by MITUTOYO Co., ltd.). Then, for each of the MD direction and the TD direction, the heat shrinkage ratio was calculated by the following formula (1), and the high wet expansion ratio was calculated by the following formula (2). The heat shrinkage ratio X of the resin film was A and the high wet expansion ratio Y was B. The table shows larger values in the MD direction and the TD direction.

Heat shrinkage X [% ] = (a-a')/a×100 (1)

High wet expansion ratio Y [% ] = (a' -a)/a×100 (2)

(2) Saturated water absorption

The measurement was performed based on JIS K7209.

(3) Peel test

The release liner was peeled off from the double-sided adhesive sheet to expose the adhesive layer (1), and a cellulose Triacetate (TAC) film (trade name "KC4UY", manufactured by konikama dada corporation) was laminated on the exposed adhesive layer (1). Then, the release liner is peeled off from the double-sided adhesive sheet to expose the adhesive layer (2), and the exposed adhesive layer (2) is bonded to an acrylic glass plate. Thus, an evaluation sample was prepared which was composed of a laminate of [ TAC film/adhesive layer (1)/resin film/adhesive layer (2)/acrylic glass plate ]. The evaluation sample was placed in an environmental tester set at a temperature of 85℃and a humidity of 85% RH for 30 minutes. Thereafter, the evaluation sample was taken out from the environmental tester to room temperature at a temperature of 25 ℃ and a humidity of 50% rh, and whether or not peeling occurred between at least any of the TAC film and the adhesive layer (1), the resin film and the adhesive layer (1), and the resin film and the adhesive layer (2) was visually confirmed. The case where peeling did not occur was evaluated as "o", and the case where peeling occurred at least at 1 was evaluated as "x".

(4) High wet shrinkage

For the TAC film, test pieces of 100mm by 100mm were cut, and evaluation points were set at positions 20mm toward the center from the midpoints of the 4 sides, respectively. The evaluation point-to-point distance b between the facing points was measured at a room temperature environment of 25℃and a humidity of 50% RH. Then, the mixture was put into an environmental tester set at a temperature of 85℃and a humidity of 85% RH for 30 minutes. Thereafter, the test piece was taken out of the environmental tester to the same environment as before being put into the environmental tester, that is, to a room temperature environment having a temperature of 25℃and a humidity of 50% RH, and then the distance b' between the evaluation points was measured by planar biaxial dimensions measurement (trade name "QVA 1517-PRO_AE 1M (SP)", manufactured by MITUTOYO, co., ltd.). Then, the high wet shrinkage was calculated from the following equation (3) for each of the MD direction and the TD direction. The high wet shrinkage Z of the TAC film was set to C. The table shows larger values in the MD direction and the TD direction.

High wet shrinkage Z [% ] = (b-b')/b×100 (3)

TABLE 1

As shown in table 1, when a resin film produced by heating a/B in a specific range was used, it was confirmed that peeling did not occur (examples). However, when a resin film having a low a/B and a high a/B is used, peeling occurs (comparative example). It was also confirmed that peeling did not occur in the peeling test (3) above, with respect to the double-sided adhesive sheet obtained in the same manner as in example 1, except that the acrylic resin film produced by heating so that the a/B was in the range of 0.3 to 2.5 was used instead of the polycarbonate resin in example 1.

The following describes variations of the disclosed invention.

[ additional note 1] A method for producing a resin film, comprising a heating step of heating a raw material film so that the ratio [ former/latter ] of the shrinkage ratio of the resin film when heated at 120 ℃ for 5 minutes to the expansion ratio when stored at 85 ℃ and 85% RH for 30 minutes is 0.3 to 2.5.

The method for producing a resin film according to item 1, wherein the heating step is performed while applying a tensile stress to the raw material film.

The method for producing a resin film according to item 1, wherein the heating step is performed while applying a tensile stress to at least one direction of the raw material film.

The method for producing a resin film according to any one of the above-mentioned items 1 to 3, wherein the heating step is performed by blowing warm air from at least one surface of the raw material film.

The method for producing a resin film according to any one of the above-mentioned items 1 to 4, wherein the raw material film is heated while being transported in the heating step.

The method for producing a resin film according to any one of supplementary notes 6 to 1 to 5, which comprises a winding step of stretching the raw material film in the longitudinal direction and winding the stretched film after the heating step to obtain a roll-shaped resin film blank.

Claims

1. A method for producing a resin film, comprising a heating step of heating a raw material film so that the ratio [ former/latter ] of the shrinkage rate of the resin film when heated at a temperature of 120 ℃ for 5 minutes to the expansion rate when stored at a temperature of 85 ℃ and a humidity of 85% RH for 30 minutes is 0.3 to 2.5.

2. The method for producing a resin film according to claim 1, wherein the heating step is performed while applying a tensile stress to the raw material film.

3. The method for producing a resin film according to claim 1, wherein the heating step is performed while applying a tensile stress in at least one direction of the raw material film.

4. The method for producing a resin film according to any one of claims 1 to 3, wherein warm air is blown from at least one surface of the raw material film and heated in the heating step.

5. The method for producing a resin film according to any one of claims 1 to 3, wherein the raw material film is heated while being conveyed in the heating step.

6. The method for producing a resin film according to any one of claims 1 to 3, comprising a winding step of winding the raw material film after the heating step while being stretched in the longitudinal direction to obtain a roll-shaped resin film blank.