WO2022185607A1

WO2022185607A1 - Laminate and engineering plastic film provided with protection film

Info

Publication number: WO2022185607A1
Application number: PCT/JP2021/039802
Authority: WO
Inventors: 桂也 ▲徳▼田; 哲雄奥山; 郷司前田; 直樹渡辺
Original assignee: 東洋紡株式会社
Priority date: 2021-03-03
Filing date: 2021-10-28
Publication date: 2022-09-09
Also published as: JPWO2022185607A1; TW202243900A

Abstract

A laminate comprising: a protection film having a base material and an adhesive layer; an engineering plastic film provided on the adhesive layer; and an inorganic substrate provided on the engineering plastic film, wherein the inorganic substrate and the engineering plastic film are laminated in contact with each other or are laminated with a silane coupling agent solely existing therebetween, the shear detachment strength between the engineering plastic film and the adhesive layer is 700 MPa or less, the Martens hardness of the adhesive layer is 30 N/mm² or less, the number of air bubbles that are located between the inorganic substrate and the engineering plastic film and that do not have a nucleus is not more than one bubble/cm².

Description

Laminates and engineering plastic films with protective films

The present invention relates to a laminate and an engineering plastic film with a protective film.

In recent years, with the aim of reducing the weight, size, thickness, and flexibility of functional elements such as semiconductor elements, MEMS elements, and display elements, the development of technology for forming these elements on polymer films has been actively carried out. That is, conventionally, as a material for the base material of electronic parts such as information communication equipment (broadcasting equipment, mobile radio, portable communication equipment, etc.), radar, high-speed information processing equipment, etc., it has heat resistance and the signal of information communication equipment Ceramics have been used to support higher frequencies (up to the GHz band), but ceramics are not flexible and are difficult to thin. uses a polymer film as the substrate.

In recent years, the use of engineering plastic films (hereinafter also referred to as "engineering plastic films") such as polyimide, aromatic polyamide, polyamideimide, polycarbonate, polyethylene naphthalate, and polyethylene terephthalate has been studied as a substrate material for manufacturing flexible electronic devices. It is Since engineering plastic film is continuously manufactured in a long length and wound up into a roll, it is generally accepted that a roll-to-roll production line is ideal for the production of flexible devices. there is
On the other hand, many conventional electronic devices such as display devices, sensor arrays, touch screens, and printed wiring boards use hard rigid substrates such as glass substrates, semiconductor wafers, and glass fiber reinforced epoxy substrates. is also configured on the premise of using such a rigid substrate. Therefore, in order to form a functional element on an engineering plastic film using existing infrastructure, the engineering plastic film is laminated to a rigid support (inorganic substrate such as a glass plate, ceramic plate, silicon wafer, metal plate, etc.), and then A process is used in which a desired element is formed on the substrate and then separated from the inorganic substrate.

By the way, in the process of forming a desired functional element in a laminate obtained by laminating an engineering plastic film and an inorganic substrate, the laminate is often exposed to high temperatures. For example, formation of functional elements such as polysilicon and oxide semiconductors requires a process in a temperature range of about 200.degree. C. to 600.degree. In the production of a hydrogenated amorphous silicon thin film, a temperature of about 200 to 300° C. may be applied to the film. Heating may be required. Therefore, the engineering plastic film forming the laminate is required to have heat resistance.

Polymer films used for the above applications should be covered with a protective film on either side or one side until just before use to prevent dust from entering between the inorganic substrate and the polymer film when they are attached to the inorganic substrate. is covered with (for example, see Patent Document 1).

WO2016/031746

The engineering plastic film described above is wound into a roll with protective films attached on both sides, and supplied in roll form. When the engineering plastic film is attached to the inorganic substrate, first, the engineering plastic film, with the protective film attached, is cut into a desired size and shape using a knife such as a Thomson type. After that, the protective film is peeled off, and the substrate is attached to the inorganic substrate.

Methods such as press and roll lamination are used to bond engineering plastic films to inorganic substrates, but roll lamination is preferable from the viewpoint of improving productivity and reducing costs brought about by high productivity.

When attaching an engineering plastic film that is protected by protective films on both sides to an inorganic substrate, from the perspective of preventing scratches on the engineering plastic film surface, peel off only the protective film on the side that is attached to the inorganic substrate before laminating. implement.

However, there were cases where air bubbles with no foreign matter acting as cores were generated between the engineering plastic film and the inorganic substrate.

Such air bubbles become noise during defect inspection in the post-process, and there is a risk that scratches on the engineering plastic film that should be detected and defects caused by adhered foreign matter may not be detected. In addition, since the process of forming the functional element is a high temperature process of 200° C. to 600° C., the air in the bubbles may expand due to heating, causing a floating between the engineering plastic film and the inorganic substrate.

The inventors of the present invention conducted a thorough study on the cause of these bubbles. As a result, surprisingly, by setting the shear peel strength between the engineering plastic film and the pressure-sensitive adhesive layer constituting the protective film and the Martens hardness of the pressure-sensitive adhesive layer within a certain range, the adhesion between the inorganic substrate and the engineering plastic film was improved. The inventors have found that air bubbles without nuclei between them can be suppressed, and have completed the present invention.

That is, the laminate according to the present invention is
a protective film having a substrate and an adhesive layer;
an engineering plastic film provided on the adhesive layer;
and an inorganic substrate provided on the engineering plastic film,
The inorganic substrate and the engineering plastic film are laminated in contact with each other, or laminated only via a silane coupling agent layer,
The shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less,
The adhesive layer has a Martens hardness of 30 N/mm ² or less,
The number of air bubbles without nuclei between the inorganic substrate and the engineering plastic film is 1/cm ² or less.

When an engineering plastic film is laminated on an inorganic substrate, a shearing force is applied to the adhesive layer of the protective film on the side that comes into contact with the lamination roll.
When a protective film having a high shear peel strength and a hard adhesive layer is used, air bubbles are generated between the engineering plastic film and the protective film when the protective film is laminated to the engineering plastic film. Then, when an engineering plastic film with a protective film in which air bubbles exist between the engineering plastic film and the protective film is used and the engineering plastic film is laminated on an inorganic substrate, pressure is not applied uniformly during the lamination process where there are air bubbles. Air bubbles with no foreign matter acting as nuclei are generated between the inorganic substrate and the engineering plastic film.
On the other hand, in the present invention, the shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less, and the Martens hardness of the adhesive layer is 30 N/mm ² or less. bubbles can be suppressed.

In addition, if the adhesive layer of the protective film is not sufficiently soft, the shear force during lamination of the engineering plastic film to the inorganic substrate cannot be fully alleviated, resulting in the formation of air bubbles without foreign matter as nuclei between the inorganic substrate and the engineering plastic film. cause it to occur.
On the other hand, in the present invention, the adhesive layer has a Martens hardness of 30 N/mm ² or less, and can be said to be sufficiently soft. Therefore, the shearing force during lamination can be sufficiently relieved, and the generation of air bubbles without foreign matter serving as nuclei between the inorganic substrate and the engineering plastic film can be suppressed.

Furthermore, if the adhesive layer of the protective film is not sufficiently soft, even if there are no air bubbles at the interface between the engineering plastic film and the protective film, the adhesive layer cannot be deformed during lamination, and the inorganic substrate and the engineering plastic film cannot be separated. The pressure cannot be transmitted uniformly between the layers, resulting in the formation of voids without nuclei.
On the other hand, in the present invention, the adhesive layer has a Martens hardness of 30 N/mm ² or less, and can be said to be sufficiently soft. Therefore, the pressure-sensitive adhesive layer can be sufficiently deformed during lamination, and pressure can be uniformly transmitted between the inorganic substrate and the engineering plastic film. As a result, it is possible to suppress the generation of air bubbles that do not contain foreign matter that serves as a nucleus.

In addition, in the present invention, since the shear peel strength between the engineering plastic film and the pressure-sensitive adhesive layer is 700 MPa or less, the protective film can be easily peeled off from the engineering plastic film.

Further, in the present invention, since the number of air bubbles without nuclei between the inorganic substrate and the engineering plastic film is 1/cm ² or less, it is possible to suppress noise during defect inspection. As a result, it is possible to suppress the impossibility of detecting scratches on the engineering plastic film that should be detected and defects due to adhered foreign matter. In addition, in the high temperature process of 200° C. to 600° C. for forming the functional element, it is possible to suppress the expansion of the air in the bubbles due to heating and the occurrence of floating between the engineering plastic film and the inorganic substrate.
In addition, the "nucleus-free bubble" refers to a bubble without any foreign matter in the bubble.

In the configuration, the engineering plastic film is preferably a polyimide film.

When the engineering plastic film is a polyimide film, it has excellent heat resistance.

In the above configuration, the substrate is preferably a polyester film or a polyolefin film.

When the substrate is a polyester film or a polyolefin film, it has excellent handleability.

In the above configuration, the substrate is preferably a polyethylene terephthalate film.

When the base material is a polyethylene terephthalate film, the handleability is superior.

In the configuration, the pressure-sensitive adhesive layer contains a urethane-based resin,
It is preferable that the adhesive layer has a gel fraction of 25% or more and 70% or less.

When the pressure-sensitive adhesive layer contains a urethane-based resin and the gel fraction of the pressure-sensitive adhesive layer is 70% or less, it can be said that the crosslink density is low. By using an acrylic resin with a low cross-linking density, it is possible to achieve a Martens hardness of 30 N/mm ² or less for the pressure-sensitive adhesive layer.

In the configuration, the pressure-sensitive adhesive layer contains a silicone-based resin,
It is preferable that the adhesive layer has a gel fraction of 25% or more and 40% or less.

When the pressure-sensitive adhesive layer contains a silicone-based resin and the gel fraction of the pressure-sensitive adhesive layer is 40% or less, it can be said that the crosslink density is low. By using a silicone-based resin with a low cross-linking density, it is possible to achieve a Martens hardness of 30 N/mm ² or less for the pressure-sensitive adhesive layer.

In the configuration, the pressure-sensitive adhesive layer contains an acrylic resin,
It is preferable that the adhesive layer has a gel fraction of 45% or more and 65% or less.

When the pressure-sensitive adhesive layer contains an acrylic resin and the gel fraction of the pressure-sensitive adhesive layer is 65% or less, it can be said that the crosslink density is low. By using an acrylic resin with a low cross-linking density, it is possible to achieve a Martens hardness of 30 N/mm ² or less for the pressure-sensitive adhesive layer.

Further, the engineering plastic film with a protective film according to the present invention is
a protective film having a substrate and an adhesive layer;
and an engineering plastic film provided on the adhesive layer,
The shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less,
The adhesive layer has a Martens hardness of 30 N/mm ² or less.

Since the shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less and the Martens hardness of the adhesive layer is 30 N/mm ² or less, air bubbles between the engineering plastic film and the protective film can be suppressed. can be done. Therefore, in the laminate obtained by laminating the engineering plastic film with the protective film on the inorganic substrate, generation of voids without nuclei between the inorganic substrate and the engineering plastic film is suppressed.

In the above structure, the number of non-nucleated cells between the engineering plastic film and the pressure-sensitive adhesive layer is preferably 50/cm ² or less.

When the number of air bubbles without nuclei between the engineering plastic film and the pressure-sensitive adhesive layer is 50/cm ² or less, the laminate obtained by laminating the engineering plastic film with a protective film to an inorganic substrate is an inorganic The generation of air bubbles without nuclei between the substrate and the engineering plastic film is greatly suppressed.

According to the present invention, it is possible to provide a laminate in which air bubbles between the engineering plastic film and the protective film are suppressed. Moreover, it is possible to provide an engineering plastic film with a protective film capable of suppressing air bubbles between the engineering plastic film and the protective film.

1 is a cross-sectional view schematically showing an engineering plastic film with a protective film according to this embodiment; FIG. FIG. 3 is a cross-sectional view schematically showing an engineering plastic film with a protective film according to another embodiment; It is a sectional view showing typically the layered product concerning this embodiment. It is a figure which shows typically an example of the silane-coupling-agent processing apparatus used by a vapor-phase deposition method. It is a figure for demonstrating a shear peeling test.

Embodiments of the present invention will be described below.

<Laminate>
The laminate according to the present embodiment comprises a protective film having a substrate and an adhesive layer,
an engineering plastic film provided on the adhesive layer;
and an inorganic substrate provided on the engineering plastic film,
The inorganic substrate and the engineering plastic film are laminated in contact with each other, or laminated only via a silane coupling agent layer,
The shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less,
The adhesive layer has a Martens hardness of 30 N/mm ² or less,
The number of non-nucleated air bubbles between the inorganic substrate and the engineering plastic film is 1/cm ² or less.

<Protective film>
The protective film has a substrate and an adhesive layer. The protective film is laminated on at least one side of the engineering plastic film, that is, the side that does not come into contact with the inorganic substrate when laminated with the inorganic substrate (the side that comes into contact with the lamination roll during lamination).

<Base material>
Although the substrate is not particularly limited, it is preferably a polyester film or a polyolefin film from the viewpoint of handleability.

In this specification, the polyester film refers to a film formed with polyester resin as the main component. The "main component" means that the polyester film contains 50% by mass or more, preferably 75% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, and polymethylene terephthalate. Examples of copolymer components include diol components such as ethylene glycol, terephthalic acid, diethylene glycol, neopentyl glycol, and polyalkylene glycol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. dicarboxylic acid components such as

Among the above polyester resins, polyethylene terephthalate is preferable. That is, the substrate is preferably a polyethylene terephthalate film. When the substrate is a polyethylene terephthalate film, it has appropriate hardness and flexibility for protecting an engineering plastic film, and is suitable as a substrate for a protective film. In addition, although polyethylene terephthalate film does not transmit ultraviolet rays (does not absorb them greatly), by combining it with a pressure-sensitive adhesive layer containing an ultraviolet absorber, it can be cut by an ultraviolet laser suitable for cutting engineering plastic films, including substrates. cutting is possible. If the base material is a material that does not transmit ultraviolet rays, the base material absorbs a large amount of the energy of the ultraviolet laser, and it takes a long time to cut the protective film and the engineering plastic film in a short time and economically. may not be able to cut In order to cut the protective film and the engineering plastic film well, a polyethylene terephthalate film to which an ultraviolet absorber is added can be used as the base material of the protective film.

In this specification, a polyolefin film specifically refers to a film formed with polyethylene resin and/or polypropylene resin as the main component. The "main component" means that the polyolefin film contains 50% by mass or more, preferably 75% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

The base material may be a single layer, may be a laminate of a plurality of layers having the same composition, or may be a laminate of a plurality of layers having different compositions. Each layer may be a layer having known functions such as antistatic and adhesion prevention.

The base material may contain various additives in the resin as necessary. Examples of the additives include fillers, antioxidants, light stabilizers, anti-gelling agents, organic wetting agents, antistatic agents, surfactants, pigments, and dyes. However, it is preferable that the base material satisfies the following numerical range in ultraviolet transmittance measurement. The substrate preferably does not contain an ultraviolet absorber. Examples of the ultraviolet absorber include those described later.

When the engineering plastic film is colorless and transparent, it is preferable to color the substrate of the protective film with a pigment or dye. If the base material of the protective film is colored, it becomes easy to perform positional alignment using a color difference sensor or the like in the step of laminating the inorganic substrate.

The protective film preferably has a transmittance of 3% or less at a wavelength of 355 nm in ultraviolet transmittance measurement (UV transmittance measurement) of a laminate of a substrate and an adhesive layer, and more preferably 2% or less. is preferred, and 1.5% or less is particularly preferred. When the transmittance of the protective film at a wavelength of 355 nm is 3% or less, the protective film and the engineering plastic film can be more suitably cut with an ultraviolet laser.

The protective film may contain an ultraviolet absorber in the base material in order to control the ultraviolet transmittance of the laminate of the base material and the pressure-sensitive adhesive layer within the above preferred range.

In the protective film, the transmittance of the adhesive layer alone at a wavelength of 355 nm may be 3% or less, and the transmittance of the substrate alone at a wavelength of 355 nm may be 3% or less. The transmittance at both wavelengths of 355 nm may be 3% or less.

Although the thickness of the base material is not particularly limited, it can be arbitrarily determined according to the standard used, for example, within the range of 12 μm or more and 500 μm or less. The thickness of the base material is more preferably 25 μm or more and 350 μm or less. When the thickness of the base material is 500 μm or less, it is possible to suppress deterioration of productivity and handling properties. Moreover, if the thickness of the base material is 12 μm or more, the lack of mechanical strength of the base material can be reduced, and breakage during peeling can be prevented.

The surface roughness Ra of the base material opposite to the inorganic substrate is preferably 0.02 μm or more, more preferably 0.025 μm or more, and still more preferably 0.03 μm or more. The upper limit is preferably 1.2 μm or less, more preferably 0.6 μm or less, even more preferably 0.3 μm or less.
As a method of controlling the surface roughness of the protective film base material within a predetermined range, a method of adding inorganic particles to the raw material resin at the time of manufacturing the film of the base material to control the surface roughness can be exemplified. As inorganic particles, a predetermined amount of known inorganic particles such as silica, alumina, calcia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium phosphate, barium sulfate, talc and kaolin may be added. The amount added varies depending on the draw ratio during production of the base film, the final thickness of the base film, the particle size distribution of the added inorganic particles, etc., but it is generally 500 ppm in mass ratio with respect to the mass of the base film resin. Above, it is preferably 1000 ppm or more, more preferably 2000 ppm or more, and the upper limit is 10% by mass or less, preferably 3% by mass or less, more preferably 10000 ppm or less.
As a method for controlling the surface roughness of the base material within a predetermined range, a method of polishing or grinding the surface of the base material to obtain a predetermined surface roughness can be exemplified.
Further, as a method for controlling the surface roughness of the base material within a predetermined range, a method of obtaining the base material by casting a film raw material onto a supporting base material prepared in advance so as to have a predetermined surface roughness can be exemplified. In addition, a method of pressing an embossed roller or the like processed into a predetermined surface shape to control the surface roughness of the base material can also be exemplified.
As a method for controlling the surface roughness of the base material within a predetermined range, a method of obtaining the base material by roughening treatment by chemical etching can be exemplified. Although the protective film may be whitened by these roughening treatments, whitening of the film due to the roughening is preferably suppressed from the viewpoint of inspection through the protective film.

The substrate can be formed into a film by a conventionally known film forming method. Examples of the film-forming method include a calendar film-forming method, a casting method in an organic solvent, an inflation extrusion method in a closed system, a T-die extrusion method, a co-extrusion method, a dry lamination method, and the like.

<Adhesive layer>
As the adhesive layer, known resins such as acrylic, silicone, rubber, polyester, and urethane can be used without particular limitation. Acrylic resins, silicone resins, and urethane resins are preferable from the viewpoint of handleability.

The acrylic resin is preferably obtained by polymerizing a monomer such as (meth)acrylic acid alkyl ester. Specific examples of the monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, ) Alkyl ( meth)acrylate compounds. A plurality of these can also be copolymerized as needed.

When the pressure-sensitive adhesive layer contains an acrylic resin, the pressure-sensitive adhesive layer preferably has a gel fraction of 45% or more and 65% or less. The gel fraction of the pressure-sensitive adhesive layer is more preferably 47% or higher, even more preferably 50% or higher. The gel fraction of the pressure-sensitive adhesive layer is more preferably 63% or less, even more preferably 60% or less. When the gel fraction of the adhesive layer is 65% or less, it can be said that the crosslink density is low. By using an acrylic resin with a low cross-linking density, it is possible to achieve a Martens hardness of 30 N/mm ² or less for the pressure-sensitive adhesive layer. On the other hand, when the gel fraction of the pressure-sensitive adhesive layer is 45% or more, cohesive failure of the pressure-sensitive adhesive layer is less likely to occur when the pressure-sensitive adhesive layer and the engineering plastic film are separated.

When the pressure-sensitive adhesive layer contains an acrylic resin, the content of the acrylic resin in the pressure-sensitive adhesive layer is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more. is.

The urethane-based resin preferably contains a urethane resin and a cross-linking agent.

The urethane resin is a resin having multiple hydroxyl groups and can be synthesized by reacting a polyol and a polyisocyanate.

The polyol refers to an organic compound having a plurality (2 or 3 or more) of hydroxyl groups (preferably at least one of alcoholic hydroxyl groups and phenolic hydroxyl groups) in one molecule. The polyisocyanate refers to an organic compound (polyfunctional isocyanate) having a plurality (2 or 3 or more) of isocyanate groups (also referred to as isocyanato groups), that is, (-N=C=O) in one molecule.

As used herein, polyurethane polyol refers to a polyurethane prepolymer having a plurality of hydroxyl groups.
In this specification, unless otherwise specified, a urethane prepolymer is a polyurethane prepolymer that can be converted into a polyurethane that has undergone further polymerization or cross-linking by having a plurality of isocyanate groups (for example, at both ends of the molecule). A polymer.

The urethane resin may be the urethane prepolymer. A urethane prepolymer is a polymer in which polymerization or cross-linking has progressed halfway, and which can be further polymerized or cross-linked. The term "prepolymer of polyurethane" or "urethane prepolymer" refers to polyurethane in a state in which polymerization or cross-linking has progressed halfway, and which can be converted into polyurethane by further progressing polymerization or cross-linking. The polyurethane prepolymer can be converted into a polyurethane that has undergone further polymerization or cross-linking, for example, by having a plurality of hydroxyl groups or isocyanate groups.

The polyol is not particularly limited. For example, as described above, the polyol may be bifunctional (bivalent, i.e., having two hydroxyl groups in one molecule) or trifunctional or higher (trivalent or higher, i.e., having three or more hydroxyl groups in the molecule). , preferably trifunctional or more, and particularly preferably trifunctional. Further, the polyol may be used alone or in combination of multiple types. Examples of the polyol include, but are not limited to, one or both of polyester polyol and polyether polyol.

The polyester polyol is not particularly limited, and examples thereof include known polyester polyols. Examples of the acid component of the polyester polyol include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of the glycol component of the polyester polyol include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, poly oxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol and the like. Examples of the polyol component of the polyester polyol include glycerin, trimethylolpropane, and pentaerythritol. Other examples include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone) and polyvalerolactone.

The molecular weight of the polyester polyol is not particularly limited, and can be used from low molecular weight to high molecular weight. A polyester polyol having a number average molecular weight of 500 to 5,000 is preferably used. If the number average molecular weight is 500 or more, it is easy to prevent gelation due to too high reactivity. Moreover, if the number average molecular weight is 5,000 or less, it is easy to prevent a decrease in reactivity and a decrease in the cohesive strength of the polyurethane polyol itself. The polyester polyol may or may not be used, but when used, the amount used is, for example, 10 to 90 mol % of the polyols constituting the polyurethane polyol.

The polyether polyol is not particularly limited, and examples thereof include known polyether polyols. Specifically, the polyether polyol is prepared by using a low-molecular-weight polyol such as water, propylene glycol, ethylene glycol, glycerin, and trimethylolpropane as an initiator, and an oxirane such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran. A polyether polyol obtained by polymerizing a compound may be used. More specifically, the polyether polyol may have two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol. The molecular weight of the polyether polyol is not particularly limited, and can be used from low molecular weight to high molecular weight. Polyether polyols having a number average molecular weight of 1,000 to 15,000 are preferably used. If the number average molecular weight is 1,000 or more, it is easy to prevent gelation due to too high reactivity. Further, when the molecular weight is 15,000 or less, it is easy to prevent a decrease in reactivity and a decrease in the cohesive strength of the polyurethane polyol itself. The polyether polyol may or may not be used, but when used, the amount used is, for example, 20 to 80 mol % of the polyols constituting the polyurethane polyol.

Part of the polyether polyol, if necessary, is ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, glycols such as pentaerythritol, ethylenediamine, N - Polyvalent amines such as aminoethylethanolamine, isophoronediamine and xylylenediamine may be substituted and used together.

Although the polyol may be a bifunctional (having two hydroxyl groups in one molecule) polyether polyol, it is preferably trifunctional or more (having three or more hydroxyl groups in one molecule). In particular, by using a polyol having a number average molecular weight of 1,000 to 15,000 and having a functionality of 3 or more, in whole or in part, it becomes easier to balance adhesive strength and removability. If the number average molecular weight is 1,000 or more, it is easy to prevent the tri- or more functional polyol from being too reactive and gelling. Further, when the number average molecular weight is 15,000 or less, it is easy to prevent a decrease in the reactivity of the tri- or more functional polyol and a decrease in the cohesive strength of the polyurethane polyol itself. More preferably, a polyol having a number average molecular weight of 2,500 to 3,500 and a tri- or higher functionality is used partially or wholly.

The polyisocyanate (organic polyisocyanate compound) is not particularly limited, but includes, for example, known aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. In addition, one type of polyisocyanate may be used alone, or a plurality of types may be used in combination.

Examples of the aromatic polyisocyanate include 1,3-phenylene diisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanatotoluene, 1,3,5-triisocyanatobenzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4' , 4″-triphenylmethane triisocyanate and the like.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and dodecamethylene diisocyanate. , 2,4,4-trimethylhexamethylene diisocyanate and the like.

Examples of the araliphatic polyisocyanate include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4- diethylbenzene, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.

Examples of the alicyclic polyisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl- 2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, etc. mentioned.

In addition, a trimethylolpropane adduct form of the above polyisocyanate, a biuret form reacted with water, a trimer having an isocyanurate ring, and the like can also be used in combination.

As the polyisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) and the like are preferable.

The reaction catalyst is not particularly limited, and for example, a known catalyst can be used. Examples of the catalyst include tertiary amine compounds and organometallic compounds.

Examples of the tertiary amine-based compound include triethylamine, triethylenediamine, 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU), and the like.

Examples of the organometallic compounds include tin-based compounds and non-tin-based compounds. Examples of the tin-based compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, tin 2-ethylhexanoate and the like. Examples of the non-tin compounds include titanium compounds such as dibutyl titanium dichloride, tetrabutyl titanate and butoxy titanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate and lead naphthenate; Iron-based such as iron 2-ethylhexanoate and iron acetylacetonate, cobalt-based such as cobalt benzoate and cobalt 2-ethylhexanoate, zinc-based such as zinc naphthenate and zinc 2-ethylhexanoate, zirconium naphthenate, etc. is mentioned.

When these catalysts are used, for example, in a system in which two kinds of polyols, polyester polyol and polyether polyol, exist, the difference in reactivity causes gelation or turbidity of the reaction solution in a single catalyst system. is likely to occur. In such a case, for example, by using two or more kinds of catalysts together, the reaction rate, the selectivity of the catalyst, etc. can be controlled, and these problems can be solved. Examples of the combination include tertiary amine/organometallic, tin/non-tin, tin/tin, etc., preferably tin/tin, more preferably dibutyltin dilaurate and 2- It is a combination of tin ethylhexanoate. The compounding ratio is not particularly limited, but for example, the weight of tin 2-ethylhexanoate/dibutyltin dilaurate is less than 1, preferably 0.2 to 0.6. If the compounding ratio is less than 1, it is easy to prevent gelation due to the balance of catalytic activity. The amount of these catalysts used is not particularly limited, but is, for example, 0.01 to 1.0% by weight based on the total amount of polyol and organic polyisocyanate.

When the catalyst is used, the reaction temperature for synthesizing the polyurethane polyol is preferably less than 100°C, more preferably 40°C to 60°C. If the temperature is less than 100°C, it is easy to control the reaction rate and the crosslinked structure, and it is easy to obtain a polyurethane polyol having a predetermined molecular weight.

In addition, when the catalyst is not used (no catalyst), the reaction temperature for synthesizing the polyurethane polyol is preferably 100°C or higher, preferably 110°C or higher. Moreover, it is preferable that the reaction time for synthesizing the polyurethane polyol is 3 hours or more in the absence of a catalyst.

The solvent used for synthesizing the polyurethane polyol is not particularly limited, and for example, known solvents can be used. Examples of the solvent include ketones such as methyl ethyl ketone, acetone and methyl isobutyl ketone, esters such as ethyl acetate, n-butyl acetate and isobutyl acetate, and hydrocarbons such as toluene and xylene. Toluene is particularly preferred in view of the solubility of polyurethane polyol, the boiling point of the solvent, and the like.

When the pressure-sensitive adhesive layer contains a urethane-based resin, the pressure-sensitive adhesive layer preferably has a gel fraction of 25% or more and 70% or less. The gel fraction of the pressure-sensitive adhesive layer is more preferably 28% or higher, even more preferably 30% or higher. The gel fraction of the adhesive layer is more preferably 68% or less, even more preferably 65% or less. When the gel fraction of the pressure-sensitive adhesive layer is 70% or less, it can be said that the crosslink density is low. By using a urethane-based resin with a low cross-linking density, it is possible to achieve a Martens hardness of 30 N/mm ² or less for the pressure-sensitive adhesive layer. On the other hand, when the gel fraction of the pressure-sensitive adhesive layer is 25% or more, cohesive failure of the pressure-sensitive adhesive layer is less likely to occur when the pressure-sensitive adhesive layer and the engineering plastic film are separated.

When the pressure-sensitive adhesive layer contains a urethane-based resin, the content of the urethane-based resin in the pressure-sensitive adhesive layer is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more. is.

When the pressure-sensitive adhesive layer contains a silicone resin, the pressure-sensitive adhesive layer preferably has a gel fraction of 25% or more and 40% or less, and the gel fraction of the pressure-sensitive adhesive layer is more preferably 25% or more, 28% or more is more preferable. The gel fraction of the pressure-sensitive adhesive layer is more preferably 38% or less, even more preferably 35% or less. When the gel fraction of the pressure-sensitive adhesive layer is 40% or less, it can be said that the crosslink density is low. By using a silicone-based resin with a low cross-linking density, it is possible to achieve a Martens hardness of 30 N/mm ² or less for the pressure-sensitive adhesive layer. On the other hand, when the gel fraction of the silicone-based resin is 25% or more, cohesive failure of the pressure-sensitive adhesive layer is less likely to occur when the pressure-sensitive adhesive layer and the engineering plastic film are separated.

When the pressure-sensitive adhesive layer contains a silicone-based resin, the content of the silicone-based resin in the pressure-sensitive adhesive layer is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more. is.

The adhesive layer may or may not contain other components as appropriate. Examples of other components include solvents, antioxidants, cross-linking inhibitors (cross-linking retarders), fillers, colorants, antifoaming agents, light stabilizers, and the like. Examples of the antioxidant include, but are not particularly limited to, phenol-based and sulfur-based antioxidants. Examples of the antifoaming agent include, but are not particularly limited to, silicone antifoaming agents and mineral oil antifoaming agents. The light stabilizer is not particularly limited, but includes, for example, hindered amine-based light stabilizers. Moreover, the said adhesive layer may contain the plasticizer as said other component, for example, and does not need to contain it. By including the plasticizer, for example, an effect of suppressing an increase in adhesive strength over time can be obtained. The "increase in adhesive strength over time" refers to a phenomenon in which, when an adhesive (for example, in the form of an adhesive sheet) is applied to the surface of an adherend, the adhesive strength to the surface of the adherend increases over time after application. Say. By suppressing this increase in adhesive strength over time, for example, the removability of the pressure-sensitive adhesive or pressure-sensitive adhesive sheet is further improved, and the contamination resistance to the surface of the adherend is further improved.

The adhesive layer may contain an ultraviolet absorber. A known ultraviolet absorber can be used as the ultraviolet absorber. Examples of the ultraviolet absorber include organic ultraviolet absorbers and inorganic ultraviolet absorbers, and organic ultraviolet absorbers are preferable from the viewpoint of transparency.

Examples of the organic UV absorbers include benzotriazole-based, benzophenone-based, cyclic iminoester-based, and combinations thereof. Among them, benzotriazole-based and cyclic iminoester-based are particularly preferable from the viewpoint of durability.

Examples of the benzotriazole-based ultraviolet absorbers include 2-[2′-hydroxy-5′-(methacryloyloxymethyl)phenyl]-2H-benzotriazole and 2-[2′-hydroxy-5′-(methacryloyloxyethyl). Phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-(methacryloyloxypropyl)phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-(methacryloyloxyhexyl)phenyl] -2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(methacryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-tert- Butyl-3′-(methacryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-(methacryloyloxyethyl)phenyl]-5-chloro-2H-benzotriazole, 2-[2 '-hydroxy-5'-(methacryloyloxyethyl)phenyl]-5-methoxy-2H-benzotriazole, 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-5-cyano-2H-benzo triazole, 2-[2′-hydroxy-5′-(methacryloyloxyethyl)phenyl]-5-tert-butyl-2H-benzotriazole, 2-[2′-hydroxy-5′-(methacryloyloxyethylphenyl]- 5-nitro-2H-benzotriazole and the like.

Examples of the benzophenone-based UV absorbers include 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxyethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'- dimethoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5,5'-disulfobenzophenone disodium salt and the like.

Examples of the cyclic iminoester-based UV absorber include 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one), 2-methyl-3,1-benzoxazine- 4-one, 2-butyl-3,1-benzoxazin-4-one, 2-phenyl-3,1-benzoxazin-4-one, 2-(1- or 2-naphthyl)-3,1-benzo Oxazin-4-one, 2-(4-biphenyl)-3,1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-m-nitrophenyl- 3,1-benzoxazin-4-one, 2-p-benzoylphenyl-3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2-o -methoxyphenyl-3,1-benzoxazin-4-one, 2-cyclohexyl-3,1-benzoxazin-4-one, 2-p-(or m-)phthalimidophenyl-3,1-benzoxazin-4 -one, 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazinone-4-one) 2,2′-bis(3,1-benzoxazin-4-one), 2,2′-ethylenebis(3,1-benzoxazin-4-one), 2,2′-tetramethylenebis(3,1-benzoxazin-4-one), 2,2′-decamethylenebis ( 3,1-benzoxazin-4-one), 2,2′-p-phenylenebis(3,1-benzoxazin-4-one), 2,2′-m-phenylenebis(3,1-benzoxazin-4-one) -4-one), 2,2′-(4,4′-diphenylene)bis(3,1-benzoxazin-4-one), 2,2′-(2,6- or 1,5-naphthalene) Bis(3,1-benzoxazin-4-one), 2,2′-(2-methyl-p-phenylene)bis(3,1-benzoxazin-4-one), 2,2′-(2- nitro-p-phenylene)bis(3,1-benzoxazin-4-one), 2,2′-(2-chloro-p-phenylene)bis(3,1-benzoxazin-4-one), 2, 2'-(1,4-cyclohexylene)bis(3,1-benzoxazin-4-one), 1,3,5-tri(3,1-benzoxazin-4-one-2-yl)benzene, etc. is mentioned.

Also, 1,3,5-tri(3,1-benzoxazin-4-one-2-yl)naphthalene, and 2,4,6-tri(3,1-benzoxazin-4-one-2-yl ) naphthalene, 2,8-dimethyl-4H,6H-benzo(1,2-d;5,4-d′)bis-(1,3)-oxazine-4,6-dione, 2,7-dimethyl- 4H,9H-benzo(1,2-d;5,4-d′)bis-(1,3)-oxazine-4,9-dione, 2,8-diphenyl-4H,8H-benzo(1,2 -d;5,4-d')bis-(1,3)-oxazine-4,6-dione,2,7-diphenyl-4H,9H-benzo(1,2-d;5,4-d' ) bis-(1,3)-oxazine-4,6-dione, 6,6′-bis(2-methyl-4H,3,1-benzoxazin-4-one), 6,6′-bis(2 -ethyl-4H,3,1-benzoxazin-4-one), 6,6′-bis(2-phenyl-4H,3,1-benzoxazin-4-one), 6,6′-methylenebis(2 -methyl-4H,3,1-benzoxazin-4-one), 6,6′-methylenebis(2-phenyl-4H,3,1-benzoxazin-4-one), 6,6′-ethylenebis( 2-methyl-4H,3,1-benzoxazin-4-one), 6,6′-ethylenebis(2-phenyl-4H,3,1-benzoxazin-4-one), 6,6′-butylenebis (2-methyl-4H,3,1-benzoxazin-4-one), 6,6'-butylenebis(2-phenyl-4H,3,1-benzoxazin-4-one), 6,6'-oxybis (2-methyl-4H,3,1-benzoxazin-4-one), 6,6′-oxybis(2-phenyl-4H,3,1-benzoxazin-4-one), 6,6′-sulfonyl Bis(2-methyl-4H,3,1-benzoxazin-4-one), 6,6'-sulfonylbis(2-phenyl-4H,3,1-benzoxazin-4-one), 6,6' -carbonylbis(2-methyl-4H,3,1-benzoxazin-4-one), 6,6'-carbonylbis(2-phenyl-4H,3,1-benzoxazin-4-one), 7, 7'-methylenebis(2-methyl-4H,3,1-benzoxazin-4-one), 7,7'-methylenebis(2-phenyl-4H,3,1-benzoxazin-4-one), 7, 7′-bis(2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-ethylenebis(2-methyl-4H,3,1-benzoxazin-4-one), 7,7′-oxybis(2-methyl-4H ,3,1-benzoxazin-4-one), 7,7′-sulfonylbis(2-methyl-4H,3,1-benzoxazin-4-one), 7,7′-carbonylbis(2-methyl -4H,3,1-benzoxazin-4-one), 6,7′-bis(2-methyl-4H,3,1-benzoxazin-4-one), 6,7′-bis(2-phenyl -4H,3,1-benzoxazin-4-one), 6,7′-methylenebis(2-methyl-4H,3,1-benzoxazin-4-one), 6,7′-methylenebis(2-phenyl -4H,3,1-benzoxazin-4-one) can also be used as a cyclic imino ester UV absorber.

Although the content of the ultraviolet absorber is not particularly limited, it is preferable that the measured value is within the following numerical range in the ultraviolet transmittance measurement (UV transmittance measurement) of the first protective film. For example, the content of the ultraviolet absorber is preferably 0.1 to 10% by weight, and 0.3 to 3% by weight, when the entire first pressure-sensitive adhesive layer is 100% by weight. is more preferred.

Although the thickness of the pressure-sensitive adhesive layer is not particularly limited, it is usually 3 to 200 μm, preferably 5 to 30 μm.

The adhesive layer is obtained by applying an adhesive composition solution on the substrate to form a coating film, and then drying the coating film under predetermined conditions. The coating method is not particularly limited, and examples thereof include roll coating, screen coating, gravure coating, and the like. The drying conditions are, for example, a drying temperature of 80 to 150° C. and a drying time of 0.5 to 5 minutes. Moreover, after coating the pressure-sensitive adhesive composition on the separator to form a coating film, the coating film may be dried under the drying conditions described above to form the pressure-sensitive adhesive layer. After that, the pressure-sensitive adhesive layer is pasted together with the separator onto the substrate. A protective film is obtained by the above.

The pressure-sensitive adhesive layer may undergo a filtration process before being applied to the substrate. The filtration accuracy (filter diameter) is preferably 0.2 μm to 10 μm, more preferably 0.2 μm to 5 μm. When the filtration accuracy is 0.2 μm or more, a long time or high pressure is not required to filter the adhesive. Therefore, it is suitable for industrial processes. When the filtration accuracy is 10 μm or less, it is possible to suitably remove foreign matter (such as gelled matter) in the pressure-sensitive adhesive that may become transfer foreign matter to the engineering plastic film, and reduce the number of transfer foreign matter to the engineering plastic film.

<Engineering plastic film (engineering plastic film)>
The engineering plastic film is a polymer compound film that retains a tensile strength of 49 MPa or more and a flexural modulus of 2.5 GPa or more even when exposed to an environment of 100° C. or higher for a long time, preferably 168 hours. preferable.
The engineering plastic film preferably has a glass transition temperature of 115° C. or higher, more preferably 130° C. or higher, and still more preferably 145° C. or higher.
Examples of the engineering plastic film include amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyamideimide, polyetherimide, polybenzoxazole, polyethylenenaphthalate, silicone resin, fluororesin, and liquid crystal. Examples include films such as polymers.
As the engineering plastic film, it is particularly preferable to use a polymer film having an imide bond. Examples of polymer films having imide bonds include films of polyimide, polyamideimide, polyetherimide, polyimidebenzoxazole, bismaleimidetriazine, and the like.

The details of the polyimide resin film (sometimes referred to as polyimide film), which is an example of the engineering plastic film, will be described below. In general, a polyimide resin film is prepared by applying a polyamic acid (polyimide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent to a support for producing a polyimide film and drying it to form a green film (hereinafter referred to as (also referred to as "polyamic acid film"), and further subjecting the green film to a high-temperature heat treatment on a polyimide film-producing support or in a state in which the green film is peeled off from the support to cause a dehydration ring-closing reaction.

Application of the polyamic acid (polyimide precursor) solution includes, for example, spin coating, doctor blade, applicator, comma coater, screen printing method, slit coating, reverse coating, dip coating, curtain coating, slit die coating, etc. Application of conventionally known solutions. means can be used as appropriate.

The diamines that make up the polyamic acid are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines, etc. that are commonly used in polyimide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferred. Diamines may be used alone or in combination of two or more.

The diamines are not particularly limited, and examples thereof include oxydianiline (bis(4-aminophenyl) ether) and paraphenylenediamine (1,4-phenylenediamine).

The tetracarboxylic acids constituting the polyamic acid include aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), and alicyclic tetracarboxylic acids, which are commonly used in polyimide synthesis. Acids (including anhydrides thereof) can be used. When these are acid anhydrides, one or two anhydride structures may be present in the molecule, but preferably those having two anhydride structures (dianhydrides) are good. Tetracarboxylic acids may be used alone, or two or more of them may be used in combination.

The tetracarboxylic acid is not particularly limited and includes, for example, pyrrolimethic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride.

The polyimide film may be a transparent polyimide film.

A colorless transparent polyimide, which is an example of the engineering plastic film, will be described. In order to avoid complication, it is simply referred to as transparent polyimide. As for the transparency of the transparent polyimide, it is preferable that the total light transmittance is 75% or more. It is more preferably 80% or more, still more preferably 85% or more, even more preferably 87% or more, and particularly preferably 88% or more. Although the upper limit of the total light transmittance of the transparent polyimide is not particularly limited, it is preferably 98% or less, more preferably 97% or less for use as a flexible electronic device. The colorless transparent polyimide in the present invention is preferably polyimide having a total light transmittance of 75% or more.

Aromatic tetracarboxylic acids for obtaining highly colorless and transparent polyimide include 4,4′-(2,2-hexafluoroisopropylidene)diphthalic acid, 4,4′-oxydiphthalic acid, bis(1,3- dioxo-1,3-dihydro-2-benzofuran-5-carboxylic acid) 1,4-phenylene, bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)benzene-1,4 -dicarboxylate, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzene-1,4-diyloxy)]dibenzene- 1,2-dicarboxylic acid, 3,3′,4,4′-benzophenonetetracarboxylic acid, 4,4′-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis (toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1, 4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[4,4′-(3-oxo-1,3-dihydro-2-benzofuran-1,1- diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[4,4′-(3-oxo-1,3-dihydro-2- benzofuran-1,1-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[4,4′-(3H-2,1-benzoxathiol- 1,1-dioxido-3,3-diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-benzophenonetetracarboxylic acid, 4,4′-[(3H -2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[(3H- 2,1-Benzoxathiol-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[ 4,4′-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4′-[4,4′-(3H-2 ,1-Benzoxathiol-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3′,4,4′-benzophenone tetracarboxylic acid, 3,3′,4,4′-benzophenonetetracarboxylic acid, 3,3′,4,4′-diphenylsulfonetetracarboxylic acid, 3,3′,4,4′-biphenyltetracarboxylic acid, 2,3,3′,4′-biphenyltetracarboxylic acid, pyromellitic acid, 4,4′-[spiro(xanthene-9,9′-fluorene)-2,6-diylbis(oxycarbonyl)]diphthalic acid, Tetracarboxylic acids such as 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]diphthalic acid and acid anhydrides thereof can be mentioned. Among these, dianhydrides having two acid anhydride structures are preferred, particularly 4,4′-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, 4,4′-oxydiphthalic Acid dianhydrides are preferred. Aromatic tetracarboxylic acids may be used alone, or two or more of them may be used in combination. The amount of aromatic tetracarboxylic acids to be copolymerized is, for example, preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass of the total tetracarboxylic acids when heat resistance is emphasized. More preferably, it is 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

Alicyclic tetracarboxylic acids include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclohexanetetracarboxylic acid, 1 , 2,4,5-cyclohexanetetracarboxylic acid, 3,3′,4,4′-bicyclohexyltetracarboxylic acid, bicyclo[2,2,1]heptane-2,3,5,6-tetracarboxylic acid, Bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid, tetrahydroanthracene -2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, decahydronaphthalene-2 ,3,6,7-tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethano-5,8-methano naphthalene-2,3,6,7-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetra Carboxylic acid (also known as "norbornane-2-spiro-2'-cyclopentanone-5'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid"), methylnorbornane- 2-spiro-α-cyclopentanone-α'-spiro-2''-(methylnorbornane)-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclohexanone- α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid (aka "norbornane-2-spiro-2'-cyclohexanone-6'-spiro-2''-norbornane -5,5″,6,6″-tetracarboxylic acid”), methylnorbornane-2-spiro-α-cyclohexanone-α′-spiro-2″-(methylnorbornane)-5,5″, 6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclopropanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane -2-spiro-α-cyclobutanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α' -Spiro-2 ''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclooctanone-α'-spiro-2''-norbornane-5,5'', 6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclononanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2 -spiro-α-cyclodecanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cycloundecanone-α′-spiro -2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α′-spiro-2″-norbornane-5,5′ ',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclotridecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid , norbornane-2-spiro-α-cyclotetradecanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclo Pentadecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclopentanone)-α'-spiro -2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclohexanone)-α′-spiro-2″-norbornane-5,5 Tetracarboxylic acids such as '',6,6''-tetracarboxylic acid and acid anhydrides thereof can be mentioned. Among these, dianhydrides having two acid anhydride structures are preferred, particularly 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic acid Acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride is preferred, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic An acid dianhydride is more preferred, and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride is even more preferred. In addition, these may be used independently and may use 2 or more types together. The amount of alicyclic tetracarboxylic acids to be copolymerized is, for example, preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass of the total tetracarboxylic acids when importance is placed on transparency. % or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

Tricarboxylic acids include aromatic tricarboxylic acids such as trimellitic acid, 1,2,5-naphthalenetricarboxylic acid, diphenylether-3,3′,4′-tricarboxylic acid, and diphenylsulfone-3,3′,4′-tricarboxylic acid. acids or hydrogenated products of the above aromatic tricarboxylic acids such as hexahydrotrimellitic acid; Glycol bistrimellitate, and their monoanhydrides and esters. Among these, monoanhydrides having one acid anhydride structure are preferred, and trimellitic anhydride and hexahydrotrimellitic anhydride are particularly preferred. In addition, these may be used individually and may be used in combination.

Dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, 4,4'-oxydibenzenecarboxylic acid, or the above aromatic dicarboxylic acids such as 1,6-cyclohexanedicarboxylic acid. Hydrogenates of oxalic acid, succinic acid, glutaric acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecadeic acid, dodecanedioic acid, 2-methylsuccinic acid, and their acid chlorides Alternatively, an esterified product and the like can be mentioned. Among these, aromatic dicarboxylic acids and hydrogenated products thereof are preferred, and terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzenecarboxylic acid are particularly preferred. In addition, dicarboxylic acids may be used alone or in combination.

Diamines or isocyanates for obtaining highly colorless and transparent polyimides are not particularly limited, and polyimide synthesis, polyamideimide synthesis, aromatic diamines, aliphatic diamines, and alicyclic diamines commonly used in polyamide synthesis. , aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and the like can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and from the viewpoint of transparency, alicyclic diamines are preferred. In addition, the use of aromatic diamines having a benzoxazole structure makes it possible to exhibit high heat resistance, high elastic modulus, low thermal shrinkage, and low coefficient of linear expansion. Diamines and isocyanates may be used alone or in combination of two or more.

Examples of aromatic diamines include 2,2′-dimethyl-4,4′-diaminobiphenyl, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis (4-amino-2-trifluoromethylphenoxy)benzene, 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl, 4,4′-bis(4-aminophenoxy)biphenyl, 4,4′- Bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone , 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoro Propane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4-amino-N-(4-aminophenyl)benzamide, 3,3'-diaminodiphenyl ether , 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 2,2′-trifluoromethyl-4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4 '-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4 '-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis [4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy)phenyl]propane, 1 , 3-bis[4-(4-aminophenoxy)phenyl]propane, 2, 2-bis[4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4-(4-aminophenoxy)phenyl]butane, 1,3-bis[4-(4-aminophenoxy)phenyl] Butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-amino phenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3-methylphenyl]propane, 2,2-bis[4-(4- aminophenoxy)-3-methylphenyl]propane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2- Bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexa Fluoropropane, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4 -aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[ 4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4 -aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis [(3-aminophenoxy)benzoyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4 '-diaminodiphenyl sulfide, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl ]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2- bis[4-(3-aminophenoxy)phenyl]ethane, bis[4-(3-aminophenoxy)phenyl]sulfoxide, 4,4′-bis[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4 '-bis[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4- (4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy) Phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6 -trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[ 4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- diamino-4-biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1, 3-bis(3-amino-4-phenoxybenzoyl)benzene, 1,4-bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-bis(4-amino-5-phenoxybenzoyl) noxybenzoyl)benzene, 1,4-bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,4-bis(3-amino -4-biphenoxybenzoyl)benzene, 1,3-bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-bis [4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzonitrile, 4,4′-[9H-fluorene-9,9-diyl]bisaniline (also known as “9,9-bis(4-aminophenyl ) fluorene”), spiro(xanthene-9,9′-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4′-[spiro(xanthene-9,9′-fluorene)-2,6 -diylbis(oxycarbonyl)]bisaniline, 4,4′-[spiro(xanthene-9,9′-fluorene)-3,6-diylbis(oxycarbonyl)]bisaniline and the like. In addition, some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine may be substituted with a halogen atom, an alkyl or alkoxyl group having 1 to 3 carbon atoms, or a cyano group, and Some or all of the hydrogen atoms in the alkyl or alkoxyl groups of 1 to 3 may be substituted with halogen atoms. Further, the aromatic diamines having a benzoxazole structure are not particularly limited, and examples thereof include 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, oxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2′-p-phenylenebis(5-aminobenzoxazole), 2 , 2′-p-phenylenebis(6-aminobenzoxazole), 1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazolo)benzene, 2,6-(4,4′-diamino diphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole , 2,6-(3,4′-diaminodiphenyl)benzo[1,2-d:5,4-d′]bisoxazole, 2,6-(3,4′-diaminodiphenyl)benzo[1,2 -d: 4,5-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3 ,3′-diaminodiphenyl)benzo[1,2-d:4,5-d′]bisoxazole and the like. Among these, 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4′-diaminodiphenylsulfone, 3,3 '-Diaminobenzophenone is preferred. Incidentally, the aromatic diamines may be used singly or in combination.

Alicyclic diamines include, for example, 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propyl cyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 4,4'-methylenebis(2,6-dimethylcyclohexylamine) and the like. Among these, 1,4-diaminocyclohexane and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-diaminocyclohexane is more preferred. Incidentally, the alicyclic diamines may be used alone or in combination.

Diisocyanates include, for example, diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3' - or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2 '- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4, 3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3, 3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4′-(2,2 bis(4-phenoxyphenyl)propane) diisocyanate, 3, 3'- or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4, Aromatic diisocyanates such as 4'-diisocyanate and 3,3'-diethoxybiphenyl-4,4'-diisocyanate, and diisocyanates obtained by hydrogenating any of these (e.g., isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate) and the like. Among them, diphenylmethane-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 3,3'- Dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and 1,4-cyclohexane diisocyanate are preferred. Diisocyanates may be used alone or in combination.

In this embodiment, the engineering plastic film is preferably a polyimide film. When the engineering plastic film is a polyimide film, it has excellent heat resistance. Further, when the engineering plastic film is a polyimide film, it can be suitably cut with an ultraviolet laser.

The thickness of the engineering plastic film is preferably 3 µm or more, more preferably 7 µm or more, still more preferably 14 µm or more, and still more preferably 20 µm or more. Although the upper limit of the thickness of the engineering plastic film is not particularly limited, it is preferably 250 μm or less, more preferably 100 μm or less, and still more preferably 50 μm or less for use as a flexible electronic device.

The average coefficient of linear expansion (CTE) of the engineering plastic film between 30°C and 250°C is preferably 50 ppm/K or less. It is more preferably 45 ppm/K or less, still more preferably 40 ppm/K or less, even more preferably 30 ppm/K or less, and particularly preferably 20 ppm/K or less. Moreover, it is preferably -5 ppm/K or more, more preferably -3 ppm/K or more, and still more preferably 1 ppm/K or more. When the CTE is within the above range, the difference in coefficient of linear expansion with a general support (inorganic substrate) can be kept small, and the engineering plastic film and the inorganic substrate are peeled off even when subjected to a process of applying heat, or the support is not supported. You can avoid warping the whole body. Here, CTE is a factor representing reversible expansion and contraction with respect to temperature. The CTE of the engineering plastic film refers to the average value of the CTE in the coating direction (MD direction) and the CTE in the width direction (TD direction) of the polyamic acid. The method for measuring the CTE of the engineering plastic film is according to the method described in Examples.

When the engineering plastic film is a transparent polyimide film, its yellowness index (hereinafter also referred to as "yellow index" or "YI") is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less. and more preferably 3 or less. Although the lower limit of the yellowness index of the transparent polyimide is not particularly limited, it is preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.3 or more for use as a flexible electronic device. is.

When the engineering plastic film is a transparent polyimide film, the haze is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and still more preferably 0.3 or less. Although the lower limit is not particularly limited, industrially, there is no problem if it is 0.01 or more, and it may be 0.05 or more.

The thermal shrinkage rate of the engineering plastic film between 30°C and 500°C is preferably ±0.9% or less, more preferably ±0.6% or less. Thermal shrinkage is a factor representing irreversible expansion and contraction with respect to temperature.

The tensile strength at break of the engineering plastic film is preferably 60 MPa or more, more preferably 80 MPa or more, and still more preferably 100 MPa or more. Although the upper limit of the tensile strength at break is not particularly limited, it is practically less than about 1000 MPa. When the tensile strength at break is 60 MPa or more, it is possible to prevent the engineering plastic film from being broken when peeled from the inorganic substrate. The tensile strength at break of the engineering plastic film refers to the average value of the tensile strength at break in the machine direction (MD direction) and the tensile strength at break in the width direction (TD direction) of the engineering plastic film. The method for measuring the tensile strength at break of the engineering plastic film is according to the method described in Examples.

The tensile elongation at break of the engineering plastic film is preferably 1% or more, more preferably 5% or more, and still more preferably 10% or more. When the tensile elongation at break is 1% or more, the handleability is excellent. The tensile elongation at break of the engineering plastic film refers to the average value of the tensile elongation at break in the machine direction (MD direction) and the tensile elongation at break in the width direction (TD direction) of the engineering plastic film. The method for measuring the tensile elongation at break of the engineering plastic film is according to the method described in Examples.

The tensile modulus of the engineering plastic film is preferably 2.5 GPa or more, more preferably 3 GPa or more, and still more preferably 4 GPa or more. When the tensile elastic modulus is 2.5 GPa or more, the engineering plastic film undergoes little elongation deformation when peeled from the inorganic substrate, and is excellent in handleability. The tensile modulus is preferably 20 GPa or less, more preferably 15 GPa or less, and even more preferably 12 GPa or less. When the tensile modulus is 20 GPa or less, the engineering plastic film can be used as a flexible film. The tensile elastic modulus of the engineering plastic film refers to the average value of the tensile elastic modulus in the machine direction (MD direction) and the tensile elastic modulus in the width direction (TD direction) of the engineering plastic film. The method for measuring the tensile modulus of the engineering plastic film is according to the method described in Examples.

The thickness unevenness of the engineering plastic film is preferably 20% or less, more preferably 12% or less, still more preferably 7% or less, and particularly preferably 4% or less. If the thickness unevenness exceeds 20%, it tends to be difficult to apply to narrow areas. The uneven thickness of the film can be obtained by measuring the thickness of the film by randomly extracting about 10 positions from the film to be measured using, for example, a contact-type film thickness meter, and calculating the thickness according to the following formula.
Film thickness unevenness (%)
= 100 x (maximum film thickness - minimum film thickness) / average film thickness

The engineering plastic film is preferably obtained in the form of being wound as a long engineering plastic film with a width of 300 mm or more and a length of 10 m or more at the time of production. Morphology is more preferred. When the engineering plastic film is wound into a roll, transportation in the form of a heat-resistant engineering plastic film wound into a roll is facilitated.

In the engineering plastic film, in order to ensure handleability and productivity, a lubricant (particles) having a particle diameter of about 10 to 1000 nm is added and contained in the engineering plastic film in an amount of about 0.03 to 3% by mass. It is preferable to provide the surface of the engineering plastic film with fine irregularities to ensure slipperiness.

<Inorganic substrate>
A glass plate, a semiconductor wafer, a metal plate, a ceramic plate, or the like can be used as the inorganic substrate. Examples of the glass plate include quartz glass, high silicate glass (96% silica), soda lime glass, lead glass, aluminoborosilicate glass, borosilicate glass (Pyrex (registered trademark)), borosilicate glass (no alkali), Borosilicate glass (microsheet), aluminosilicate glass, etc. are included. Among these, those having a coefficient of linear expansion of 5 ppm/K or less are desirable. "EAGLE", "AN100" manufactured by Asahi Glass Co., Ltd., "OA10" manufactured by Nippon Electric Glass Co., Ltd., "AF32" manufactured by SCHOTT Co., Ltd., and the like are desirable. Examples of the semiconductor wafer include silicon wafers, germanium, silicon-germanium, gallium-arsenide, aluminum-gallium-indium, nitrogen-phosphorus-arsenic-antimony, SiC, InP (indium phosphide), InGaAs, GaInNAs, LT, LN, and ZnO. (zinc oxide), CdTe (cadmium telluride), ZnSe (zinc selenide), and the like. Examples of the metal plate include single element metals such as W, Mo, Pt, Fe, Ni, and Au, alloys such as Inconel, Monel, Nimonic, carbon copper, Fe—Ni system Invar alloys, Super Invar alloys, and various stainless steels. included. In addition to these metals, multi-layer metal plates obtained by adding other metal layers and ceramic layers are also included. As the ceramic plate, a single or composite sintered body of alumina, magnesia, calcia, silicon nitride, boron nitride, aluminum nitride, beryllium oxide, or the like can be used. When a ceramic substrate is used in the present invention, it is preferable to use a ceramic substrate whose surface is smoothed by glass glaze treatment.

The surface roughness of the inorganic substrate is preferably in the range of 0.01 to 2 nm. At least, when the inorganic substrate is laminated with the engineering plastic, the surface roughness of the surface opposite to the engineering plastic film is preferably in the range of 0.01 to 2 nm. Furthermore, the preferred range of surface roughness is 0.01 to 0.8 nm, more preferably 0.01 to 0.3 nm. By controlling the surface roughness of the inorganic substrate within this range, adhesion with the engineering plastic film, which has a smooth surface, which is suitable for forming functional elements, is improved, and peeling of the engineering plastic film during the process can be suppressed. can.

Although the thickness of the inorganic substrate is not particularly limited, the thickness is preferably 10 mm or less, more preferably 3 mm or less, and still more preferably 1.3 mm or less from the viewpoint of handleability. Although the lower limit of the thickness is not particularly limited, it is preferably 0.07 mm or more, more preferably 0.15 mm or more, and still more preferably 0.3 mm or more.

The inorganic substrate and the engineering plastic film are laminated in contact with each other, or laminated via only the silane coupling agent layer.

<Silane coupling agent layer>
As used herein, the silane coupling agent refers to a compound containing 10% by mass or more of Si (silicon) component. The silane coupling agent preferably further has an alkoxy group in its structure. Moreover, it is desirable that the silane coupling agent does not contain a methyl group. By using the silane coupling agent layer, the thickness of the layer between the engineering plastic film and the inorganic substrate can be reduced. As a result, the amount of degassed components during heating is small, the elution is less likely to occur even in a wet process, and even if elution does occur, the amount of elution is minimal. Since the silane coupling agent improves heat resistance, it preferably contains a large amount of a silicon oxide component, and particularly preferably has heat resistance at a temperature of about 400°C.

The thickness of the silane coupling agent layer is preferably less than 0.2 μm. The range for use as a flexible electronic device is preferably 100 nm or less (0.1 μm or less), more preferably 50 nm or less, and even more preferably 10 nm. When normally produced, the thickness is about 0.10 μm or less. Also, in a process that requires as little silane coupling agent as possible, a thickness of 5 nm or less can be used. If the thickness is less than 1 nm, the peel strength may be lowered or there may be a portion where the adhesive is not adhered, so the thickness is preferably 1 nm or more.

The silane coupling agent is not particularly limited, but preferably has an amino group or an epoxy group. Specific examples of silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(amino ethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, 2- (3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane vinyltrichlorosilane, vinyl trimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxysilane propyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 - acryloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, tris-(3-trimethoxysilyl propyl)isocyanurate, chloromethylphenethyltrimethoxysilane, chloromethyltrimethoxysilane, and the like. Preferred among these are N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)- 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, 2-(3, 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, aminophenyltrimethoxysilane, amino phenethyltrimethoxysilane, aminophenylaminomethylphenethyltrimethoxysilane and the like. When heat resistance is required in the process, it is preferable to use an aromatic link between Si and an amino group.

As described above, in the laminate of the present embodiment, the shear peel strength between the engineering plastic film and the pressure-sensitive adhesive layer is 700 MPa or less, preferably 500 MPa or less. Since the shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less, the engineering plastic film can absorb the shear force generated when the engineering plastic film and the protective film (the adhesive layer) are laminated. and the protective film (the pressure-sensitive adhesive layer). In addition, since the shear peel strength between the engineering plastic film and the pressure-sensitive adhesive layer is 700 MPa or less, the shearing force generated during lamination can be absorbed when the engineering plastic film with the protective film is attached to the inorganic substrate. Therefore, it is possible to suppress the generation of air bubbles between the inorganic substrate and the engineering plastic film. The method for measuring the shear peel strength is according to the method described in Examples.
The shear peel strength can be controlled by the composition of the pressure-sensitive adhesive layer.

In the laminate of the present embodiment, the adhesive layer has a Martens hardness of 30 N/mm ² or less, preferably 21 N/mm ² or less. Since the Martens hardness of the pressure-sensitive adhesive layer is 30 N/mm ² or less, wettability between the engineering plastic film and the pressure-sensitive adhesive layer is good. In addition, since the Martens hardness of the pressure-sensitive adhesive layer is 30 N/mm ² or less, it is sufficiently soft, and unevenness, wrinkles, and air bubbles are less likely to occur during lamination of the engineering plastic film and the protective film, and processing is easy. Further, since the adhesive layer has a Martens hardness of 30 N/mm ² or less, it is possible to alleviate the shearing force generated during lamination of the engineering plastic film and the inorganic substrate. As a result, it is possible to suppress the generation of air bubbles between the inorganic substrate and the engineering plastic film. The method for measuring the Martens hardness is according to the method described in Examples.
The Martens hardness can be controlled by the composition of the pressure-sensitive adhesive layer and the hardness and crosslink density of the resin used in the pressure-sensitive adhesive layer. For example, as the resin constituting the adhesive layer, a low hardness urethane resin with a low crosslink density, a low hardness silicone resin with a low crosslink density, and a low hardness acrylic resin with a low crosslink density are used. use.

In the laminate of this embodiment, the number of non-nucleated air bubbles between the inorganic substrate and the engineering plastic film is 1/cm ² or less. As described above, the shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less, and the Martens hardness of the adhesive layer is 30 N/mm ² or less. It becomes possible to achieve the number of non-nucleated bubbles between 1/cm ² or less. The lower limit of the number of bubbles is preferably small, and the number of bubbles is, for example, 0/cm ² or more.
The method for measuring the number of voids without nuclei between the inorganic substrate and the engineering plastic film is according to the method described in Examples.

In the laminate of this embodiment, the peel strength between the engineering plastic film and the inorganic substrate is preferably 0.3 N/cm or less. This makes it very easy to separate the engineering plastic film from the inorganic substrate after the device is formed on the engineering plastic film. Therefore, it is possible to manufacture a device connection body that can be mass-produced, thereby facilitating the manufacture of flexible electronic devices. The peel strength is preferably 0.25 N/cm or less, more preferably 0.2 N/cm or less, still more preferably 0.15 N/cm or less, and particularly preferably 0.12 N/cm or less. is. Moreover, the peel strength is preferably 0.03 N/cm or more. It is more preferably 0.06 N/cm or more, still more preferably 0.08 N/cm or more, and particularly preferably 0.1 N/cm because the laminate does not peel off when forming a device on the engineering plastic film. cm or more. The peel strength is the value of the laminate (initial peel strength) after bonding the engineering plastic film and the inorganic substrate together and heat-treating the laminate at 100° C. for 10 minutes in an air atmosphere. Further, it is preferable that the peel strength of the laminate obtained after the initial peel strength measurement is further heat treated at 300° C. for 1 hour in a nitrogen atmosphere is within the above range (peel strength after heat treatment at 300° C.).

In the laminate of the present embodiment, the adhesive strength between the protective film and the engineering plastic film is preferably in the range of 0.001 to 0.3 N/cm. The adhesion strength between the engineering plastic film and the inorganic substrate is preferably 0.3 N/cm or less for easy separation in the post-process. It is possible to remove the protective film without

The peeling speed when peeling the protective film and the engineering plastic film is preferably 50 mm/min or less, more preferably 100 mm/min or less.
Here, when peeling the protective film and the engineering plastic film, if a speed-dependent pressure-sensitive adhesive layer is used, the adhesive strength (peel strength) between the protective film and the engineering plastic film is reduced by high-speed peeling. may exceed the peel strength (adhesive strength) between the engineering plastic film and the inorganic substrate. In this case, by appropriately selecting the peeling speed within the range of the peeling speed, the interface to be peeled can be selected.

<Engineering plastic film with protective film>
The engineering plastic film with a protective film according to this embodiment is
a protective film having a substrate and an adhesive layer;
and an engineering plastic film provided on the adhesive layer,
The shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less,
The adhesive layer has a Martens hardness of 30 N/mm ² or less.

Since the protective film and the engineering plastic film have already been explained in the explanation of the laminate, explanations thereof will be omitted here.

As described above, in the engineering plastic film with protective film of the present embodiment, the shear peel strength between the engineering plastic film and the pressure-sensitive adhesive layer is 700 MPa or less, preferably 500 MPa or less. Since the shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less, the engineering plastic film can absorb the shear force generated when the engineering plastic film and the protective film (the adhesive layer) are laminated. and the protective film (the pressure-sensitive adhesive layer). In addition, since the shear peel strength between the engineering plastic film and the pressure-sensitive adhesive layer is 700 MPa or less, the shearing force generated during lamination can be absorbed when the engineering plastic film with the protective film is attached to the inorganic substrate. Therefore, it is possible to suppress the generation of air bubbles between the inorganic substrate and the engineering plastic film. The method for measuring the shear peel strength is according to the method described in Examples.
The shear peel strength can be controlled by the composition of the pressure-sensitive adhesive layer.

In the engineering plastic film with protective film of the present embodiment, the adhesive layer has a Martens hardness of 30 N/mm ² or less, preferably 21 N/mm ² or less. Since the Martens hardness of the pressure-sensitive adhesive layer is 30 N/mm ² or less, wettability between the engineering plastic film and the pressure-sensitive adhesive layer is good. In addition, since the Martens hardness of the pressure-sensitive adhesive layer is 30 N/mm ² or less, it is sufficiently soft, and unevenness, wrinkles, and air bubbles are less likely to occur during lamination of the engineering plastic film and the protective film, and processing is easy. Further, since the adhesive layer has a Martens hardness of 30 N/mm ² or less, it is possible to alleviate the shearing force generated during lamination of the engineering plastic film and the inorganic substrate. As a result, it is possible to suppress the generation of air bubbles between the inorganic substrate and the engineering plastic film. The method for measuring the Martens hardness is according to the method described in Examples.
The Martens hardness can be controlled by the composition of the pressure-sensitive adhesive layer and the hardness and crosslink density of the resin used in the pressure-sensitive adhesive layer. For example, as the resin constituting the pressure-sensitive adhesive layer, use a low hardness urethane resin with a low cross-linking density, a low hardness silicone resin with a low cross-linking density, or a low hardness acrylic resin with a low cross-linking density. and the like.

In the engineering plastic film with a protective film of the present embodiment, the number of air bubbles without nuclei between the engineering plastic film and the pressure-sensitive adhesive layer is preferably 50/cm ² or less, and 45/cm ² or less. more preferably 40/cm ² or less. The lower limit of the number of bubbles is preferably small, but the number of bubbles is, for example, 0/cm ² or more, and industrially may be 1/cm ² or more.
When the number of air bubbles without nuclei between the engineering plastic film and the pressure-sensitive adhesive layer is 50/cm ² or less, the laminate obtained by laminating the engineering plastic film with a protective film to an inorganic substrate is an inorganic The generation of air bubbles without nuclei between the substrate and the engineering plastic film is greatly suppressed.

<Method for producing engineering plastic film with protective film>
FIG. 1 is a cross-sectional view schematically showing an engineering plastic film with a protective film according to this embodiment.

As shown in FIG. 1, the engineering plastic film 10 with a protective film is
a protective film 12 having a substrate 14 and an adhesive layer 16;
and an engineering plastic film 18 provided on the adhesive layer 16 .

The manufacturing method of the engineering plastic film 10 with a protective film is not particularly limited, and a known method can be adopted. For example, the protective film 12 and the engineering plastic film 18 are prepared separately, and the protective film 12 is attached to one surface of the engineering plastic film 18 to obtain the engineering plastic film 10 with the protective film.

An engineering plastic film with a protective film only needs to have a protective film laminated on one side of the engineering plastic film, and another protective film may be laminated on the other side.

FIG. 2 is a cross-sectional view schematically showing an engineering plastic film with a protective film according to another embodiment.
As shown in FIG. 2, the engineering plastic film 11 with a protective film is
a protective film 12 having a substrate 14 and an adhesive layer 16;
an engineering plastic film 18;
A protective film 20 having a substrate 22 and an adhesive layer 24,
The protective film 12 is laminated on one side of the engineering plastic film 18,
A protective film 20 is laminated on the other surface of the engineering plastic film 18 .
The adhesive layer 16 is laminated facing one surface of the engineering plastic film 18 , and the adhesive layer 24 is laminated facing the other surface of the engineering plastic film 18 .

A method for manufacturing the engineering plastic film 11 with a protective film is not particularly limited, and a known method can be adopted. For example, the protective film 12, the engineering plastic film 18, and the protective film 20 are separately produced, the protective film 12 is attached to one surface of the engineering plastic film 18, and the protective film 20 is attached to the other surface of the engineering plastic film 18. The engineering plastic film 11 with a protective film can be obtained by laminating them together.

<Method for manufacturing laminate>
FIG. 3 is a cross-sectional view schematically showing a laminate according to this embodiment.

As shown in FIG. 3, the laminate 40 according to this embodiment is
a protective film 12 having a substrate 14 and an adhesive layer 16;
an engineering plastic film 18 provided on the adhesive layer 16;
and an inorganic substrate 42 provided on the engineering plastic film 18,
The inorganic substrate 42 and the engineering plastic film 18 are laminated in contact with each other, or laminated via only a silane coupling agent layer (not shown).

The laminate 40 can be produced, for example, by the following procedure.
First, an engineering plastic film 10 with a protective film and an inorganic substrate 42 are prepared. When using the engineering plastic film 11 with a protective film in which protective films are provided on both sides of the engineering plastic film 18, the protective film 20 provided on the other side of the engineering plastic film 11 with a protective film is peeled off. Thus, the engineering plastic film 10 with a protective film can be obtained. When providing the layered product 40 with a silane coupling agent layer, at least one surface of the inorganic substrate 42 is treated with a silane coupling agent.

Next, one surface of the inorganic substrate 42 (when a silane coupling agent layer is provided, the surface treated with the silane coupling agent) and the engineering plastic film 18 of the engineering plastic film 10 with a protective film are superimposed. can be obtained by pressing the laminated body 40 . The surface of the engineering plastic film 18 on which the protective film 12 is not provided is treated with a silane coupling agent in advance. The laminate 40 can also be obtained by lamination.
As the silane coupling agent treatment method, known methods such as spin coating, spray coating, and dip coating can be used, and the silane coupling agent vapor generated by heating the silane coupling agent is deposited on the inorganic substrate. However, processing is possible (vapor deposition method).

FIG. 4 is a diagram schematically showing an example of a silane coupling agent treatment apparatus used in vapor deposition.
As shown in FIG. 4, the silane coupling agent processing apparatus includes a processing chamber (chamber) 36 connected to a gas inlet 32, an exhaust port 38, and a chemical liquid tank (silane coupling agent tank) 33. As shown in FIG. A chemical liquid tank (silane coupling agent tank) 33 is filled with a silane coupling agent, and the temperature is controlled by a hot water tank (hot water bath) 34 having a heater 35 . A gas introduction port 39 is connected to the chemical liquid tank (silane coupling agent tank) 33 so that gas can be introduced from the outside. The gas flow rate is adjusted by a flow meter 31 connected to the gas inlet 39 . When the gas is introduced from the gas inlet 39, the vaporized silane coupling agent in the chemical liquid tank 33 is pushed out into the processing chamber 36, and the substrate 37 (inorganic substrate, engineering plastic film, etc.) placed in the processing chamber 36 is pushed out. It is deposited as a silane coupling agent layer on top.

Examples of the method of pressurization include ordinary pressing or laminating in the air or pressing or laminating in a vacuum. For example, above 200 mm), lamination in air is desirable. On the other hand, in the case of a laminate having a small size of about 200 mm or less, pressing in a vacuum is preferable. The degree of vacuum is sufficient with a normal oil rotary pump, and about 10 Torr or less is sufficient. A preferable pressure is 1 MPa to 20 MPa, more preferably 3 MPa to 10 MPa. If the pressure is high, the substrate may be damaged, and if the pressure is low, some parts may not adhere. The preferred temperature is 90° C. to 300° C., more preferably 100° C. to 250° C. If the temperature is high, the film may be damaged, and if the temperature is low, adhesion may be weak.

As described above, the laminate 40 according to the present embodiment is obtained.

Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to the following examples as long as it does not exceed the gist thereof.

Commercially available films were used as the engineering plastic films F1 and F2.
F1: Upilex (registered trademark) 25S (polyimide film manufactured by Ube Industries, Ltd., thickness 25 μm)
F2: Xenomax (registered trademark) F15LR2 (polyimide film manufactured by Toyobo Co., Ltd., thickness 15 μm)

<Preparation of Engineering Plastic Film F3: Synthesis of Polyamic Acid Solution>
After replacing the inside of the reaction vessel equipped with a nitrogen inlet tube, a reflux tube, and a stirring rod with nitrogen, 33.36 parts by mass of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 270.37 parts by mass of N-methyl-2-pyrrolidone (NMP) and a dispersion of colloidal silica in dimethylacetamide ("Snowtex (registered trademark) DMAC-ST" manufactured by Nissan Chemical Industries) were dissolved. At this time, the dispersion (“Snowtex (registered trademark) DMAC-ST” manufactured by Nissan Chemical Industries, Ltd.) in which colloidal silica is dispersed in dimethylacetamide has silica in the polyamic acid solution with a total polymer solid content of 0.14 mass. %. Then, 9.81 parts by weight of 1,2,3,4-cyclobutanetetracarboxylic anhydride (CBDA), 11.34 parts by weight of 3,3′,4,4′-biphenyltetracarboxylic acid (BPDA) ), and 4.85 parts by mass of (ODPA) as a solid were added portionwise, followed by stirring at room temperature for 24 hours. After that, 165.7 parts by mass of DMAc (N,N-dimethylacetamide) was added to dilute, and polyamic acid solution 1 (TFMB//CBDA/BPDA/ODPA with a solid content of 18% by mass and a reduced viscosity of 2.7 dl/g) was added. molar ratio=1.00//0.48/0.37/0.15).

<Production of engineering plastic film F3>
Polyamic acid solution 1 was applied to the non-lubricating surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater so that the final film thickness was 25 μm. It was dried at 110° C. for 10 minutes. After drying, the polyamic acid film that has acquired self-supporting properties is separated from the A4100 film used as the support, passed through a pin tenter having a pin sheet with pins arranged thereon, and gripped by inserting the ends of the film into the pins so that the film does not break. and conveyed by adjusting the interval between the pin sheets so that unnecessary slack does not occur, and heated under the conditions of 250° C. for 3 minutes, 300° C. for 3 minutes, and 350° C. for 6 minutes to initiate the imidization reaction. proceeded. After that, the film was cooled to room temperature for 2 minutes, and portions of the film with poor flatness at both ends were cut off with a slitter and rolled up into a roll to obtain 500 m of engineering plastic film F3 with a width of 450 mm.

<Tensile elastic modulus, tensile strength at break, and tensile elongation at break of engineering plastic film>
Test pieces were obtained by cutting the engineering plastic films F1 to F3 into strips of 100 mm×10 mm in the machine direction (MD direction) and the width direction (TD direction). A test piece was cut from the center portion in the width direction. Using a tensile tester (manufactured by Shimadzu Corporation, Autograph (R), model name AG-5000A), the temperature is 25 ° C., the tensile speed is 50 mm / min, and the distance between chucks is 40 mm. Elastic modulus, tensile strength at break and tensile elongation at break were measured. Table 1 shows the results.

<Linear expansion coefficient (CTE) of engineering plastic film>
For the engineering plastic films F1 to F3, in the machine direction (MD direction) and the width direction (TD direction), the expansion ratio is measured under the following conditions, and the intervals are 2 ° C. such as 30 ° C. to 32 ° C. and 32 ° C. to 34 ° C. This measurement was performed up to 300° C., and the average value of all measured values was calculated as CTE. Table 1 shows the results.
Equipment name; TMA4000S manufactured by MAC Science
Sample length; 20 mm
Sample width; 2 mm
Heating start temperature; 25°C
Heating end temperature; 400°C
Temperature rise rate; 5°C/min
atmosphere; argon

<Commercial protection film>
Protective films P1, 2 and 4 were commercially available.
P1: Industrial FIXFILM (registered trademark) HG2 manufactured by Fujicopian Co., Ltd.
P2: Industrial FIXFILM (registered trademark) HG3 manufactured by Fujicopian Co., Ltd.
P4: Sun A Kaken Co., Ltd. SUNYTECT (registered trademark) SAT type

<Production of protective film>
The following substrates were prepared.
PET film: manufactured by Toyobo Co., Ltd., A4100, 25 μm, 50 μm (polyethylene terephthalate film)
PET film: Cosmo Shine SRF (registered trademark) manufactured by Toyobo Co., Ltd., 80 μm
PP film: manufactured by Toray Industries, Inc., Torayfan (registered trademark), one-sided corona treatment, 26 μm (polypropylene film)

<Preparation of adhesive composition 1>
In a separable flask, 55.3 parts by mass of polyol (trifunctional, polyol obtained by addition polymerization of propylene oxide and ethylene oxide to glycerin, SANNIX (registered trademark) GL3000 manufactured by Sanyo Chemical Industries, Ltd.), 4.7 parts by mass of Duranate D101 (polyisocyanate manufactured by Asahi Kasei Chemicals Co., Ltd.), 39.7 parts by mass of toluene, and 0.02 parts by mass of dibutyltin dilaurate (DBTDL) are added and heated at 45 ° C. to 55 ° C. for 2 hours with stirring to react. let me After 2 hours from the start of heating, the mixture was cooled to 40°C or lower. After cooling, 0.28 parts by mass of an antioxidant was added and stirred until uniform to obtain a polyurethane polyol-containing composition 1. To 100 parts by mass of polyurethane polyol-containing composition 1, 7.7 parts by mass of Duranate D101, 2 parts by mass of an ultraviolet absorber (Cyasorb UV-3638 (manufactured by CYTEC)), and 50 parts by mass of ethyl acetate are blended. Stir well. The adhesive composition 1 was obtained by filtering the obtained adhesive composition with a PTFE cartridge filter (0.45 μm).

<Production of protective film P3>
The pressure-sensitive adhesive composition 1 was applied to a substrate (PP) so that the thickness of the pressure-sensitive adhesive when dried was 10 to 15 μm. After that, it was dried by heating at 130° C. for 2 minutes, and left still for 3 days in a constant temperature bath at 40° C. (aging step) to cure (crosslink) the adhesive to prepare a protective film P3.

<Preparation of adhesive composition 2>
Coronate HX (Tosoh 1.5 parts by weight of polyisocyanate for coatings manufactured by Co., Ltd.) and 0.3 parts by weight of KP-341 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., polyether-modified organosiloxane) as modified organosiloxane are added and mixed by stirring. Thus, an adhesive composition 2 was obtained.

<Production of protective film P5>
The obtained adhesive composition 2 was applied on a PET film having a thickness of 25 μm and dried at 100° C. to remove the solvent, thereby forming a surface protective film P5 having an adhesive layer formed on the PET film. got

<Production of protective film P6>
While stirring 100 parts by mass of urethane-based solvent-based adhesive US-902-50 (manufactured by Lion Specialty Chemicals, ethyl acetate solvent, solid content 50%), 5.4 parts by mass of cross-linking agent N (manufactured by Lion Specialty Chemicals) , and 2 parts by mass of an ultraviolet absorber (Cyasorb UV-3638 (manufactured by CYTEC)) were added and reacted at 40° C. for 20 minutes. After filtering the obtained solution with a PTFE cartridge filter (0.45 μm), it is coated on a PET film that has been previously corona-treated so that the final film thickness is 10 μm, and heated at 100° C. for 2 minutes. to obtain a protective film P6.

<Preparation of protective film P7>
2-Ethylhexyl acrylate/methyl methacrylate/acrylic acid monomers were blended in a weight ratio of 85/15/3, and 2,2'-azobis-isobutyronitrile was used as a catalyst in ethyl acetate under a nitrogen stream. Polymerization yielded a removable acrylic pressure-sensitive adhesive having a degree of polymerization Mw of 700,000 to 800,000 and a solid content of 30%. The removable acrylic pressure-sensitive adhesive and Coronate L (manufactured by Tosoh Corporation, polyisocyanate for paint) were blended at a weight ratio of 100:3 to obtain a pressure-sensitive adhesive composition 3. The pressure-sensitive adhesive composition 3 obtained was coated on one side of a PET film having a thickness of 25 μm and dried at 100° C. for 3 minutes to obtain a protective film P7.

<Preparation of protective film P8>
PF8 was obtained in the same manner as P7 except that a PET film having a thickness of 50 μm was used as the base material.

<Preparation of adhesive composition 4>
In a separable flask equipped with a stirrer, a reflux condenser, and a thermometer, 100 parts by mass of glycerin PO EO (trade name: Sannix GL-3000), 4.5 parts by mass of hexamethylene diisocyanate, and 56.5 parts by mass Parts of toluene and 0.03 parts by mass of dibutyltin dilaurate were charged, and the temperature was gradually raised while stirring, and the reaction was carried out at 60° C. for 3 hours. When the NCO groups in the content after the reaction were measured using an infrared spectrophotometer (IR), no residual NCO groups could be confirmed. This confirmed that the synthesis of the urethane prepolymer having hydroxyl groups was completed. Then, this content was cooled to 40° C. or less, and 0.26 parts by mass of an antioxidant and 13.4 parts by mass of ethyl acetate were added to obtain a urethane prepolymer solution having hydroxyl groups. To 100 parts by mass of this urethane prepolymer solution (60 parts by mass as a solid content), a mixed solution of 18 parts by mass of Pine Crystal D-6011 and 18 parts by mass of toluene, totaling 36 parts by mass and 10 parts by mass of Coronate L-45E was added, and the adhesive composition 4 was obtained by stirring well.

<Preparation of protective film P9>
The pressure-sensitive adhesive composition 4 was applied to a PET film having a thickness of 25 μm and allowed to stand for 2 minutes in a hot air circulating dryer set at 100° C. to evaporate the solvent. This pressure-sensitive adhesive sheet was allowed to stand in an environment of 40° C. for 3 days to complete the curing reaction of the pressure-sensitive adhesive and the polyisocyanate cross-linking agent, thereby obtaining a protective film P9.

<Preparation of adhesive composition 5>
An adhesive composition 5 was obtained by mixing the following.
Linear polyorganosiloxane having vinyl groups only at both ends (solvent-free type, Mw: 80,000): 68.30 parts Organohydrogenpolysiloxane (solvent-free type, Mw: 2,000): 0.41 Part platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., PL-56): 1.00 parts reaction control agent (3-methyl-1-butyn-3-ol): 0.10 parts toluene: 30.19 parts

<Preparation of protective film P10>
The pressure-sensitive adhesive composition 5 was applied to a COSMOSHINE SRF having a thickness of 80 μm, and allowed to stand for 2 minutes in a hot air circulating dryer set at 100° C. to evaporate the solvent. This pressure-sensitive adhesive sheet was allowed to stand in an environment of 40° C. for 3 days to complete the curing reaction of the pressure-sensitive adhesive and the polyisocyanate cross-linking agent, thereby obtaining protective film P10.

Table 2 shows the combinations of protective film substrates and adhesives used in Examples and Comparative Examples.

<Measurement of gel fraction of adhesive layer>
About the produced protective film, only the adhesive layer was scraped off with a cutter knife, and the weight A of the adhesive was measured. Next, after the same test piece was immersed in THF (tetrahydrofuran) at 25°C for 24 hours, the gel was taken out and dried at 100°C for 2 hours, and the weight B was measured.
The gel fraction was calculated from the following formula. Table 2 shows the results.
Gel fraction (%) = (B/A) x 100

<Measurement of Martens hardness of adhesive layer>
The hardness of the pressure-sensitive adhesive layer of the protective film was measured using a dynamic ultra-micro hardness tester (manufactured by Shimadzu Corporation, DUH-211S). The substrate side of the protective film was fixed to a slide glass using Aron Alpha (registered trademark), and the measurement was performed with a 50-fold objective lens, a load speed of 0.2926 mN/s, and a pushing depth of 1 μm. Triangular 115 was used as an indenter. Table 3 shows the measurement results.

<Preparation of engineering plastic film 1 with protective film>
Laminated film 1 in Example 1 was obtained by bonding P1 to one side (the side to be bonded to the inorganic substrate) of engineering plastic film F2 and P1 to the other side. The bonding was specifically performed by lamination in a clean environment. Lamination was performed between a metal roll and a rubber roll, and the temperature during lamination was normal temperature of 22° C. and 52% RH, and the sheets were successively attached one by one. The unwinding tension at this time was 120N for the polyimide film and 160N for the protective film. Almost the same tension was applied to the winding side.

<Production of engineering plastic films 2 to 12 with protective film>
Protective film-attached engineering plastic films 2 to 11 were obtained in the same manner as the protective film-attached engineering plastic film 1, except that the combination of the protective film and the engineering plastic film used was changed to the combination shown in Table 3. P1 was laminated on the surface of the engineering plastic film to be bonded to the inorganic substrate from the viewpoint of preventing scratches on the surface and adhesion of foreign substances.

<Shear peeling test>
FIG. 5 is a diagram for explaining the shear peel test. First, as shown in FIG. 5, a laminated film in which an engineering plastic film 18 and a protective film 12 are bonded together was prepared. The protective film 18 is composed of the adhesive layer 16 and the base material 14 . The width of the laminated film was 10 mm, and the adhesive layer 16 and the engineering plastic film 18 were laminated and cut so that the contact area was 10 mm×25 mm. In order to prevent the base material 14 or the engineering plastic film 18 from breaking during shear peeling, a support film 41 (made of polystyrene, thickness 0.8 mm) is applied to the surfaces of the base material 14 and the engineering plastic film 18 that do not come into contact with the adhesive layer 16. It was attached with double-sided tape. The protective film 12 and the engineering plastic film 18 are each held with a chuck together with the support film 41, and a tensile tester (manufactured by Shimadzu Corporation, Autograph (R), model name AG-5000A) is used at 25 ° C. and 100 mm / min. A shear peel test was performed. Table 3 shows the results.

<Number of bubbles between engineering plastic film/protective film>
For engineering plastic films 1 to 12 with a protective film, 30 points were observed at 100 times using a digital microscope VH-Z100R manufactured by Keyence (the range visible with the microscope is counted as 1 point), and the core foreign matter. No air bubble counts were performed. Specifically, three sheets of the protective film were cut out to a size of 10 cm×10 cm, and measurements were taken at 10 points on each of the four corners, between them, and at two points near the center. That is, a total of 30 points were measured with three sheets. Note that the range of one visual field when observed with a digital microscope VH-Z100R at a magnification of 100 is 8.6×10 ⁶ μm ² . Table 3 shows the results. Observation was performed from the surface of the protective film that was not attached to the inorganic substrate.

<Preparation of laminate with inorganic substrate>
(Example 1)
First, a glass substrate was prepared. The glass substrate is OA10G glass (manufactured by NEG Co., Ltd.) having a thickness of 0.7 mm cut into a size of 100 mm×100 mm. The glass substrate used was washed with pure water, dried, irradiated with a UV/O ₃ irradiation device (SKR1102N-03 manufactured by LAN Technical Co., Ltd.) for 1 minute, and then washed. Next, a silane coupling agent (SCA) was applied onto the glass substrate by a vapor phase coating method to form a silane coupling agent layer, thereby obtaining a first laminate (step A). Specifically, the application of the silane coupling agent to the glass substrate was performed using the silane coupling agent treatment apparatus shown in FIG. 130 g of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-903) was placed in a 1 L chemical solution tank, and the water bath outside was heated to 42°C. The emerging vapors were then sent into the chamber along with clean dry air. The gas flow rate was 22 L/min, and the substrate temperature was 21.degree. The temperature of clean dry air was 23° C. and 1.2% RH. Since the exhaust was connected to the negative pressure exhaust port, it was confirmed by a differential pressure gauge that the chamber had a negative pressure of about 2 Pa.

The engineering plastic film with a protective film was cut into 70 mm x 70 mm pieces, and the protective film on the surface to be attached to the inorganic substrate was peeled off. The silane coupling agent layer of the glass treated with the silane coupling agent and the engineering plastic film with the protective film were laminated together, and the glass substrate, the silane coupling agent layer, the engineering plastic film, and the protective film were laminated in this order. A laminate was obtained. A laminator (MRK-1000 manufactured by MCK Co.) was used for lamination, and the lamination conditions were air source pressure: 0.7 MPa, temperature: 22° C., humidity: 55% RH, and lamination speed: 50 mm/sec.

(Examples 2-9, Comparative Examples 1-3)
A laminate was produced in the same manner as in Example 1, except that the engineering plastic film with a protective film used was changed.

<Number of bubbles between glass substrate/engineering plastic film>
The laminates of Examples and Comparative Examples were heated at 110 ° C. for 10 minutes, and then observed at 30 locations at 100 times using a digital microscope VH-Z100R manufactured by Keyence from the glass surface side (with a microscope The visible area is counted as one point), and the number of bubbles without nuclei and foreign matter was counted. Note that the range of one visual field when observed with a digital microscope VH-Z100R at a magnification of 100 is 8.6×10 ⁶ μm ² . Table 4 shows the results.

<Results>
In engineering plastic films 1 to 8 and 12 with a protective film using a protective film with a shear peel strength of 700 MPa or less between the engineering plastic film and the protective film and a Martens hardness of the adhesive layer of 30 N/mm ² or less, the engineering plastic film/protective film It was confirmed that the number of air bubbles without nuclei was as small as 40/cm ² or less, and that the number of air bubbles without nuclei between the glass substrate/engineering plastic film was suppressed to 5/cm ² or less when bonded to the inorganic substrate. did it.

REFERENCE SIGNS

LIST

10, 11 Engineering plastic film with protective film 12 Protective film 14 Base material 16 Adhesive layer 18 Engineering plastic film (engineering plastic film)
20 Protective film 22 Base material 24 Adhesive layer 40 Laminate 42 Inorganic substrate 41 Support film

Claims

a protective film having a substrate and an adhesive layer;
an engineering plastic film provided on the adhesive layer;
and an inorganic substrate provided on the engineering plastic film,
The inorganic substrate and the engineering plastic film are laminated in contact with each other, or laminated only via a silane coupling agent layer,
The shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less,
The adhesive layer has a Martens hardness of 30 N/mm 2 or less,
A laminate, wherein the number of non-nucleated air bubbles between the inorganic substrate and the engineering plastic film is 1/cm 2 or less.
A laminate characterized in that the engineering plastic film is a polyimide film.
The laminate according to claim 1 or 2, wherein the base material is a polyester film or a polyolefin film.
The laminate according to any one of claims 1 to 3, wherein the base material is a polyethylene terephthalate film.
The adhesive layer contains a urethane-based resin,
5. The laminate according to any one of claims 1 to 4, wherein the adhesive layer has a gel fraction of 25% or more and 70% or less.
The pressure-sensitive adhesive layer contains a silicone resin,
5. The laminate according to any one of claims 1 to 4, wherein the adhesive layer has a gel fraction of 25% or more and 40% or less.
The pressure-sensitive adhesive layer contains an acrylic resin,
5. The laminate according to any one of claims 1 to 4, wherein the adhesive layer has a gel fraction of 45% or more and 65% or less.
a protective film having a substrate and an adhesive layer;
and an engineering plastic film provided on the adhesive layer,
The shear peel strength between the engineering plastic film and the adhesive layer is 700 MPa or less,
An engineering plastic film with a protective film, wherein the adhesive layer has a Martens hardness of 30 N/mm 2 or less.
9. The engineering plastic film with a protective film according to claim 8, wherein the number of non-nucleated air bubbles between the engineering plastic film and the pressure-sensitive adhesive layer is 50/cm 2 or less.