JP2001247834A - Curable pressure-sensitive adhesive composition, curable pressure-sensitive adhesive sheet, and bonding method of optical or electronic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curable pressure-sensitive adhesive composition which prevents a plastic substrate, or the like, from being warped or distorted, realizes excellent adhesive force and heat resistance, is high in thickness accuracy, and hardly contains air bubbles and to prepare a curable pressure-sensitive adhesive sheet prepared by using the adhesive and to provide a simple and convenient method for bonding optical or electronic substrates. SOLUTION: The adhesive composition contains a resin component comprising 40-90 wt.% polyester resin and 10-60 wt.% epoxy resin and an effective amount of a cationic photopolymerization initiator, and an alicyclic epoxy resin accounting for 10-90 wt.% of the epoxy resin. The adhesive sheet is prepared by forming a layer of the adhesive composition on at least one side of a carrier. The bonding method uses the adhesive sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable adhesive composition, a curable adhesive sheet using the curable adhesive composition, and an optical device using the curable adhesive sheet. The present invention relates to a method for bonding a substrate or an electronic substrate.

[0002]

2. Description of the Related Art A curable adhesive sheet (including a curable adhesive tape) can be bonded at room temperature like a normal adhesive sheet, and cured (post-cured) after bonding by any method. This is an adhesive material that can be converted into an adhesive to exhibit excellent adhesive performance. This curable pressure-sensitive adhesive sheet does not need to be applied to an adherend before bonding like a normal liquid adhesive, and has advantages such as easy positioning since it can be re-applied. Excellent workability and usability.

On the other hand, the electronic substrate is a plate-like or sheet-like substrate including a circuit board such as a PCB or an FPC or a high-density integrated circuit such as an IC or an LSI. In recent years, with the miniaturization of electronic devices, these electronic substrates have been increasingly mounted at a high density. The electronic substrate is not a single layer, but a plurality of substrates are laminated or a PCB and an FPC are bonded. In addition, various measures have been taken to make effective use of the limited space. Conventionally, multi-layering of substrates has been performed by laminating using an adhesive or by sequentially laminating by build-up. In recent years, however, the thickness of the substrate has become increasingly thinner, and the number of layers has increased to more than 10 layers. It has become.

The optical substrate is intended to optically record information. For example, an information recording layer called a pit is formed on one surface of a transparent plastic substrate such as an optical disk by laser light or the like. Things. When reproducing the recorded information, a laser beam is applied to the pits, and the information is sensed by the reflected light. For this reason,
A metal reflection film is formed on the pit by vacuum sputtering. In an advanced information recording medium such as a digital video disk (DVD), a plurality of optical substrates are bonded to form a multilayer information recording layer in order to improve the information recording capacity.

Conventionally, a light-curing adhesive or a transparent double-sided tape has been used for bonding the plurality of optical substrates. For example, Japanese Patent Application Laid-Open No. A method for producing a DVD using a photo-cationically curable adhesive made of a suitable cationically polymerizable substance is disclosed. In the case of this manufacturing method, since bonding is performed by photocationic curing, there is an advantage that warpage and distortion of an optical disk are reduced as compared with a bonding method using a thermosetting adhesive.

Further, JP-A-11-353709 and “Electronic Materials”, June 1996, pp. 46-49 (published by the Industrial Research Institute) describe double-sided pressure-sensitive adhesive sheets used for bonding DVDs. A double-sided double-sided disk (SD-9) with a double-sided pressure-sensitive adhesive sheet that uses styrene-butadiene-styrene block copolymer-based pressure-sensitive adhesives and acrylic resin-based pressure-sensitive adhesives and has excellent transparency, uniform thickness, and excellent adhesive strength. Glued.

In the SD-9, a semi-transparent recording layer is provided on two disks, and the recording layers are adhered to each other with an adhesive or a double-sided adhesive sheet. For reading information, the adhesive layer is required to have high transparency and thickness accuracy. In the case of bonding of SD-9 using the double-sided pressure-sensitive adhesive sheet, the thickness accuracy can be easily controlled as compared with the bonding method of applying a liquid adhesive, and
Since it is possible to bond in a short time by pressure-sensitive bonding,
There are advantages such as increased productivity of the bonding process. Further, since the double-sided pressure-sensitive adhesive sheet can be cut into an arbitrary shape in advance, there is an advantage that an optical disk having a complicated bonding shape can be easily bonded.

As described above, since the electronic substrate and the optical substrate are formed by laminating a plurality of substrates, a high bonding reliability and a simple bonding method are required for an interlayer bonding material between the substrates. In particular, since pits must be accurately read on an optical substrate, high thickness accuracy is also required.

However, when a liquid adhesive is used for bonding an optical substrate or an electronic substrate, a coating process or a special coating device is required. (Drying process and drying device). These processes and apparatuses have a problem that, when manufacturing an optical information recording medium such as an optical substrate, the manufacturing cost increases and the manufacturing efficiency (yield) decreases. In addition, since the adhesive is in a liquid state, the coating thickness tends to be non-uniform, and when the optical substrate or the electronic substrate is multi-layered, the entire thickness becomes non-uniform, and when the information density increases, the pit reading is performed. There is also a problem that accuracy is reduced.

On the other hand, when a double-sided pressure-sensitive adhesive sheet composed of a support and a pressure-sensitive adhesive is used for bonding an optical substrate or an electronic substrate, the pressure-sensitive adhesive generally has a lower cohesive force than the adhesive, so There is a problem that the strength and heat resistance are poor, and sufficient durability and adhesion reliability cannot be obtained. In addition, since the double-sided pressure-sensitive adhesive sheet has high tackiness (tack) and is strongly bonded at the same time as pressure bonding, positioning of the bonding becomes difficult, and the optical substrate or the electronic substrate may be distorted or bubbles may be entrained. There is also a problem. In order to facilitate the above-mentioned positioning with a double-sided pressure-sensitive adhesive sheet, the surface of the pressure-sensitive adhesive layer is wetted with water (so-called water adhesion), and then the tack is reduced.
A method such as bonding using a device such as a vacuum press may be adopted, but in any case, the bonding process becomes complicated, and a problem that productivity is reduced occurs.

In addition, plastic is often used as a substrate used for an optical substrate or an electronic substrate. However, these plastic substrates are warped or deformed after bonding due to distortion at the time of molding and a difference in thermal expansion coefficient inherent to the material. May occur. It is expected that the mounting of optical substrates and electronic substrates, the density of line pitches, the integration of information pits, and the like will further advance, and means for suppressing the warpage and deformation of the substrates will be required. However, conventional adhesives tend to have a non-uniform thickness, making it difficult to increase the density and integration of line pitches and information pits. There is a problem that it is difficult to suppress warpage or deformation of the substrate because it is insufficient.

[0012]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to have excellent tackiness and initial tackiness at room temperature before curing, and to provide an adhesive before or after laminating an adherend. Curing, and exerts a sufficient cohesive force after curing, so that, for example, it is possible to suppress the warpage and deformation of the plastic substrate, to exhibit excellent adhesive strength and heat resistance, and to cure the adhesive. Curable pressure-sensitive adhesive composition having high thickness accuracy when formed as a bonded sheet and hardly involving air bubbles, and a curable pressure-sensitive adhesive sheet using the curable pressure-sensitive adhesive composition, and An object of the present invention is to provide a simple method for bonding an optical substrate or an electronic substrate using the curable adhesive sheet.

[0013]

According to the first aspect of the present invention, there is provided a curable adhesive composition comprising 40 to 90% by weight of a polyester resin and 10 to 6% by weight of an epoxy resin in the total resin composition.
0% by weight and an effective amount of a cationic photopolymerization initiator are contained, and the ratio of the alicyclic epoxy resin in the epoxy resin is 10 to 90% by weight.

A curable adhesive sheet according to a second aspect of the present invention is characterized in that the curable adhesive composition according to the first aspect is laminated on at least one surface of a support. And

Further, in the method for bonding an optical substrate or an electronic substrate according to a third aspect, the curable adhesive sheet according to the second aspect is provided on a surface of one of the optical substrates or the electronic substrate to be bonded. Before or after irradiating the adhesive sheet with light having an active wavelength, the support is peeled off as necessary to expose the adhesive layer, and the other adhesive is placed on the adhesive sheet. Characterized in that the optical substrate or the electronic substrate described above is bonded and adhered.

Hereinafter, in the present specification, "curable adhesive composition" and "curable adhesive sheet" are abbreviated simply as "adhesive composition" and "adhesive sheet", respectively. .

The polyester resin used in the present invention is a general term for a polymer formed by condensation polymerization of a diol and a dicarboxylic acid, and has various properties by changing the type and combination of the diol and the dicarboxylic acid. Is obtained.

Specific examples of the polyester-based resin include, for example, “Byron” series and “Vylonal” series manufactured by Toyobo Co., Ltd., “Elitel” series manufactured by Unitika, and Dainippon Ink and Chemicals, Inc. “Takelac” series manufactured by Takeda Pharmaceutical Co., Ltd., and “Kuraboru” series manufactured by Kuraray Co., Ltd. The above polyester resins may be used alone or in combination of two or more.

The polyester resin has a high polarity since it has an ester group in the molecule and a hydroxyl group or a carboxyl group at the molecular terminal. For example, PET, PVC, ABS, PE
Excellent adhesion to highly polar materials such as N, polycarbonate and metal. In addition, since it has crystallinity and high cohesion,
Appropriate cohesion is given to the adhesive composition before curing.

The glass transition temperature (Tg) of the polyester-based resin is not particularly limited depending on the bonding temperature, and is not particularly limited, but is generally preferably 100 ° C. or less, more preferably 50 ° C. It is as follows. If the Tg of the polyester-based resin exceeds 100 ° C., the cohesive strength of the polyester-based resin becomes too high, and the tackiness and initial tackiness of the pressure-sensitive adhesive composition are reduced, and it is necessary to adhere at a high temperature. Although the workability may be reduced, the cohesive force can be adjusted by the epoxy resin described later, and therefore, it cannot be uniquely determined.

The number average molecular weight of the polyester resin is not particularly limited, but is generally 3
000 to 100,000 is preferred. If the number average molecular weight of the polyester resin is less than 3,000, the cohesive strength may be insufficient, and if it exceeds 100,000, the compatibility with the epoxy resin or other additives may be reduced. is there.

Since the polyester resin has a high cohesive force based on crystallinity even at a low molecular weight, the adhesive composition containing the same has a low tackiness (tack), and immediately after lamination, the tackiness is low. And there is an advantage that the entrained bubbles are easily released.

On the other hand, over time, the adhesive composition containing the polyester resin wets and spreads to the interface of the adherend, and the adhesion area increases. At this time, when the molecules of the polyester-based resin flow, the functional group having the highest affinity for the adherend is oriented, so that the adhesive force is improved with time. Adhesive compositions have the advantage of developing very high adhesion after curing.

Further, since the polyester resin is taken into the gel structure formed by curing the epoxy resin and the molecular mobility is significantly restricted, the adhesive composition after curing exhibits a high cohesive force. . This is because a functional group in the polyester resin, particularly a hydroxyl group, and an epoxy group in the epoxy resin are cationically polymerized and crosslinked.

The epoxy resin used in the present invention is:
It is a compound (monomer or oligomer) having at least two epoxy groups at the molecular terminals. This epoxy resin generally has high reactivity, and thus has a high curing rate,
In addition, since cationic polymerization is carried out by a photo-cationic polymerization initiator, which will be described later, and a highly crosslinked form is constructed and cured, the adhesive composition has a remarkably improved elastic modulus after curing, and has excellent adhesive strength and heat resistance. Can be expressed.

Examples of the epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin; and phenol novolak type epoxy resin and cresol novolak type epoxy resin. Novolak type epoxy resin; alicyclic epoxy type resin; glycidyl ether type epoxy resin; glycidylated amine type epoxy resin; halogenated epoxy type resin; or epoxy such as glycidylated polyester, glycidylated polyurethane, glycidylated acrylic An addition polymer of a group-containing monomer or oligomer may, for example, be mentioned. These epoxy resins may be used alone or in combination of two or more.

The epoxy resin may be a modified epoxy resin modified with another resin, if necessary, as long as the object of the present invention is not hindered. A functional group-introduced epoxy resin into which a reactive functional group such as a bond is introduced may be used.

Examples of the modified epoxy resin and the functional group-introduced epoxy resin include a urethane-modified epoxy resin, a polysulfide-modified epoxy resin, and an acrylonitrile-butadiene rubber having a terminal carboxyl group (C
TBN) modified epoxy resin, acrylonitrile-butadiene rubber containing terminal amine group (ATBN) modified epoxy resin, crosslinked acrylonitrile-butadiene rubber (crosslinked NBR) particle-dispersed epoxy resin, carboxyl group-containing crosslinked NBR particle-dispersed epoxy resin, glycidyl Examples of the epoxy resin include a group-containing crosslinked NBR particle-dispersed epoxy resin, a crosslinked acrylic rubber particle-dispersed epoxy resin, and a chelate-modified epoxy resin. These modified epoxy resins and functional group-introduced epoxy resins may be used alone,
More than one type may be used in combination.

The epoxy resin is not particularly limited, but is preferably a compound (monomer or oligomer) having a number average molecular weight of 5,000 or less at room temperature, more preferably 3,000 or less. If the number average molecular weight of the epoxy resin exceeds 5,000, the compatibility with the polyester resin is reduced, phase separation occurs, or the polyester resin is not sufficiently incorporated into the cured matrix, and the adhesive strength and heat resistance are reduced. May not be improved sufficiently.

As a specific example of the epoxy resin, for example, a product name “Epicoat” manufactured by Yuka Shell Epoxy Co., Ltd.
Series, product name "Epon" series manufactured by Shell Chemical Co., Ltd., product name "Adeka Resin" series and "Adeka Optmer" series manufactured by Asahi Denka Kogyo Co., Ltd., product name "Ceroxide" series manufactured by Daicel Chemical Industries, "Cyclomer""Series,the" Epo Friend "series and the" Eporide "series.

In the present invention, among the above epoxy resins, alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl are particularly preferably used. Specific examples of the alicyclic epoxy resin, for example,
Examples include the "Celoxide" series manufactured by Daicel Chemical Industries, Ltd., and the "Optomer KRM" series manufactured by Asahi Denka Kogyo.

The alicyclic epoxy resin has a high cationic polymerizability and forms a cured matrix faster than other epoxy resins. That is, when an alicyclic epoxy resin is used, a gel component (solvent-insoluble component) is generated by a cured matrix immediately after irradiation with light having an active wavelength, and cohesive strength is increased. Therefore, even after bonding, a certain initial cohesive force can be obtained, for example, since it becomes possible to suppress the warpage and deformation of the substrate,
The parallel accuracy of the optical substrate and the electronic substrate is significantly improved.

The epoxy resin used in the present invention needs to contain 10 to 90% by weight of the alicyclic epoxy resin.

If the content of the alicyclic epoxy resin in the epoxy resin is less than 10% by weight, the generation of the gel component immediately after the light irradiation does not sufficiently occur, so that the initial cohesive force is not improved. It becomes difficult to suppress the warpage and deformation of the substrate. Conversely, when the content of the alicyclic epoxy resin in the epoxy resin exceeds 90% by weight, the reaction between the alicyclic epoxy resins proceeds first, and the functional groups in the polyester resin, especially Since the reaction with the hydroxyl group does not proceed sufficiently, the polyester resin becomes difficult to be taken into the cured matrix. Therefore, the gel fraction after curing of the adhesive composition becomes low, and the adhesive strength and heat resistance become insufficient, or conversely, the gel fraction due to the reaction between alicyclic epoxy resins immediately after light irradiation. Is too high, and the tackiness (tack) of the adhesive composition becomes insufficient. In addition, since the molecular orientation of the polyester resin is hindered, the initial adhesive strength and the adhesive strength after curing become insufficient.

It is necessary that the resin composition constituting the adhesive composition of the present invention contains 40 to 90% by weight of the polyester resin and 10 to 60% by weight of the epoxy resin. .

When the content of the polyester resin in the resin composition is less than 40% by weight, or when the content of the epoxy resin exceeds 60% by weight, the obtained adhesive composition or the adhesive composition is not cured. The elastic modulus after curing of the adhesive sheet becomes too high, so that the peeling adhesive strength and impact resistance to the adherend become insufficient, and conversely, the content of the polyester-based resin in the resin composition exceeds 90% by weight. Alternatively, if the content of the epoxy resin is less than 10% by weight, the crosslink density after curing of the obtained adhesive composition or adhesive sheet will not be sufficiently increased, resulting in insufficient cohesive force. In addition, heat resistance and deformation stress resistance become insufficient.

Further, a cationically polymerizable compound other than the epoxy resin may be added to the above resin composition as needed as long as the achievement of the object of the present invention is not hindered.

Examples of the cationically polymerizable compound include monomers, oligomers and polymers having at least one cationically polymerizable functional group such as an epoxy group, a vinyl ether group, an episulfide group, an ethyleneimine group and a hydroxyl group in the molecule. Can be These cationically polymerizable compounds other than the epoxy resins may be used alone or in combination of two or more.

The cationically polymerizable functional group equivalent contained in the adhesive composition of the present invention is not particularly limited, but is preferably not more than 5000 g-resin / mol. The cationically polymerizable functional group equivalent is 5000 g.
If it exceeds -resin / mol, the cationically polymerizable functional group concentration in the adhesive composition becomes low, the cationic polymerization reaction does not proceed sufficiently, and the adhesive strength and heat resistance after curing become insufficient. Sometimes.

The cationic photopolymerization initiator used in the present invention is activated by irradiating light to generate a photocationic polymerization initiator and generates the epoxy resin or the epoxy resin as required at a relatively low energy. It is only necessary that the cationically polymerizable compound other than the epoxy resin to be added be subjected to cationic photopolymerization. For example, an ionic photoacid generating type photocationic polymerization initiator may be used, or a nonionic light An acid-generating photocationic polymerization initiator may be used.

Examples of the ionic photoacid generating type photocationic polymerization initiator include onium salts such as aromatic diazonium salts, aromatic halonium salts and aromatic sulfonium salts, iron-allene complexes, titanocene complexes, and arylsilanols. -Organometallic complexes such as aluminum complexes.

Specific examples of the ionic photoacid generating type photocationic polymerization initiator include, for example, trade names “OPTMER SP-150” and “OPTMER SP-” manufactured by Asahi Denka Kogyo Co., Ltd.
170 ", a product name" U "manufactured by General Electronics
VE-1014 ", product name" CD-1 "manufactured by Sartomer
012 "and the like.

Examples of the nonionic photoacid generating type cationic photopolymerization initiator include nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenolsulfonic acid ester, diazonaphthoquinone, N-hydroxyimidosulfonate and the like. No.

The above cationic photopolymerization initiator may be used alone or in combination of two or more. When two or more cationic photopolymerization initiators are used in combination, multistage curing may be performed using two or more different cationic photopolymerization initiators having different effective active wavelengths. Further, for example, one or two kinds of photopolymerization initiators other than the photocationic polymerization initiator such as a photoradical polymerization initiator and a photoanionic polymerization initiator, and photosensitizers such as benzophenone and 9,10-anthraquinone, for example. The above may be used in combination. In this case, the wavelength of the light for activating the photoradical polymerization initiator or the photoanionic polymerization initiator does not need to be equal to the wavelength of the light for activating the photocationic polymerization initiator.

The amount of the cationic photopolymerization initiator to be added depends on the reactivity and molecular weight of the epoxy resin and the cationic polymerizable compound other than the epoxy resin optionally added, or the adhesive composition or adhesive. It may be appropriately set according to the viscoelasticity or the like to be imparted to the adhesive sheet, and is not particularly limited. 0.0001
It is preferable that the amount of addition is such that it is generated by mol% or more. If the amount of the cationic photopolymerization initiator is less than the above amount, the cationic photopolymerization may not proceed sufficiently, and the curing speed may be slow, or the adhesive strength and heat resistance after curing may be insufficient.

Examples of the light for activating the above cationic photopolymerization initiator include microwaves, infrared rays, visible rays, ultraviolet rays, X-rays, α-rays, β-rays, γ-rays, and electron beams. Among them, light having a wavelength higher than ultraviolet light, which is highly safe and advantageous in terms of cost, is preferably used, and particularly preferably used is ultraviolet light having a wavelength of 200 to 400 nm, which is easy to handle, simple and has a high energy amount. It is. Examples of the light source that generates the ultraviolet light include a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a microwave excitation lamp, a metal halide lamp, a chemical lamp, and a xenon lamp.

The cationic photopolymerization initiator generates an active cation by being irradiated with the above-mentioned light, and the cationic polymerizable compound other than the epoxy resin and the epoxy resin optionally added is subjected to a cationic polymerization reaction. Let it cure. The cationic polymerization reaction has no polymerization inhibition due to oxygen as seen in the radical polymerization reaction, and the active cations once generated continue the polymerization reaction in a chain even after light blocking, so by controlling the rate of the cationic polymerization reaction, The adhesive composition or adhesive sheet in a semi-cured state capable of maintaining tackiness even after light irradiation can be obtained.

In this case, it is possible to bond the adhesive composition or the adhesive sheet in a semi-cured state over time while the adhesive property is maintained. Progress, and finally, a strong adhesive force such as an adhesive and heat resistance are developed. Therefore, it is possible to bond an opaque material that does not transmit light, and it is also possible to bond a material having low heat resistance because the polymerization reaction proceeds at room temperature without heating.

When the adherend is light-transmitting, it is needless to say that the adhesive composition or the adhesive sheet can be cured by irradiating light after bonding. The substrate may be bonded simultaneously with the front and back via a pressure-sensitive adhesive composition or a pressure-sensitive adhesive sheet, and by irradiating light after bonding, the bonding may be performed in a continuous process, or conversely, After irradiating the adhesive composition or the adhesive sheet which is not bonded to the substrate with light, the substrate may be bonded simultaneously or sequentially. Which of the above processes should be adopted may be appropriately determined in consideration of the light transmittance and productivity of the adherend.

The adhesive composition or adhesive sheet of the present invention is cured with time even at room temperature due to cationic polymerization. That is, for example, a bonded body such as a bonded substrate is cured only by being left in a room and does not require special curing (aging), so that the process load is small. Of course, since the curing reaction is accelerated by heat or light, curing (aging) by heat or light can further shorten the curing time.

The adhesive composition of the present invention may contain an elastomer, a tackifier, a filler, a filler, a bulking agent, a thixotropic agent, and a softening agent, if necessary, as long as the achievement of the object of the present invention is not hindered. ,
One of various additives such as a plasticizer, a stabilizer, an antioxidant, a crosslinking agent, a crosslinking assistant, a flame retardant, an antistatic agent, a coloring agent, and an organic solvent.
Seeds or two or more kinds may be added.

The method for producing the adhesive composition of the present invention is not particularly limited, and may be performed at room temperature or at room temperature using a mixer such as a homodisper, a homomixer, a universal mixer, a planetarium mixer, a kneader, or a three-roll machine. Under heating, a predetermined amount of each of the essential components of the polyester resin, the epoxy resin, and the cationic photopolymerization initiator, and one of the cationic polymerizable compounds other than the epoxy resin and the above various additives, which are added as necessary. The desired adhesive composition can be obtained by uniformly stirring and mixing the seed or two or more kinds of each predetermined amount.

The adhesive composition of the present invention is applied as it is to one or both surfaces of the adherend, and irradiated with light before or after the adherence of the adherend, and photo-cationic polymerization is performed. And may be cured, but in order to reduce the influence on the adherend and to obtain better handling workability and simplicity, the adhesive composition is laminated on at least one surface of the support in advance. It is preferable to use it in the form of an adhesive sheet processed into a sheet.

Next, the adhesive sheet of the present invention is obtained by laminating the above-mentioned adhesive composition of the present invention on at least one surface of a support. In addition, the support referred to here is not only a support generally used as a base material of a normal pressure-sensitive adhesive sheet such as cellophane or kraft paper, but also a release film or a release film usually used as a separator. Release paper and the like are also included.

The adhesive sheet of the present invention may be a single-sided adhesive sheet, a double-sided adhesive sheet, or a support-type adhesive sheet. Alternatively, a non-support type adhesive sheet may be used. If the adhesive composition is applied to the non-release surface of the support, it becomes a support type adhesive sheet.If the adhesive composition is applied to the release surface of the support, it becomes a non-support type. It becomes an adhesive sheet.

The method for producing the above-mentioned pressure-sensitive adhesive sheet is not particularly limited. For example, a roll-coating method, a gravure coating method, a die coating method, a spin coating method, a casting coating method, a calendar coating method may be applied to a sheet-like support surface. ,
Various coating methods such as extrusion coating, offset printing,
A direct coating method or a direct printing method in which the adhesive composition is applied or printed by various printing methods such as a screen printing method to obtain an adhesive sheet through a drying step or a cooling step as necessary. After applying or printing the pressure-sensitive adhesive composition on the release surface of the release film or release paper by the above-mentioned various coating methods or various printing methods, and optionally through a drying step or a cooling step, the support surface A desired adhesive sheet can be obtained by a transfer method of laminating the adhesive sheet to obtain an adhesive sheet.

Examples of the support include a polyester resin film such as a polyethylene terephthalate (PET) film, a polyolefin resin film,
Various types of sheet-like materials such as a plastic film such as a TPX film, a metal foil or a metal deposit, paper, cloth, and a nonwoven fabric may be used, and these may be used alone or in combination as desired. In addition, if necessary, these supports may be subjected to a releasing treatment, a surface oxidation treatment such as a corona treatment, an easy adhesion treatment such as a primer coating, a shaping treatment such as embossing or matting, and a friction treatment. By performing a surface treatment such as a lamination treatment such as printing, vapor deposition, or lamination, it becomes possible to obtain an adhesive sheet having various characteristics.

For example, the surface of the adhesive composition is protected with a plastic film that has been subjected to a release treatment with a non-silicone resin-based release agent such as a silicone resin-based release agent or a resin having a long-chain alkyl group. Thereby, an adhesive sheet having excellent shape workability such as cutting and punching can be obtained.
By using a pressure-sensitive adhesive sheet that has been previously processed into the shape of the bonding surface by cutting, punching, or the like, the bonding process can be simplified. Further, the bonding process may be simplified by simultaneously performing the bonding and the shape processing, or the bonding process may be simplified by first performing the bonding and then collectively performing the shape processing on a plurality of obtained joined bodies. . Further, by manufacturing the adhesive sheet by the printing method, it becomes possible to process the adhesive surface without cutting or punching, etc., so that unnecessary parts are not discarded, and the manufacturing cost is reduced. Is reduced.

The thickness of the adhesive sheet of the present invention is not particularly limited, but is generally preferably 1 μm to 1 mm. If the thickness of the adhesive sheet is less than 1 μm, the adhesive strength may be insufficient, and conversely 1 mm
If it exceeds, it may take a long time to cure, and the productivity may decrease.

The bonding method using the pressure-sensitive adhesive sheet of the present invention is performed by roll lamination, pressing, pressing by finger pressure or the like. The adhesive composition and the adhesive sheet of the present invention,
Since it has excellent tackiness and initial tackiness at room temperature, it can be easily bonded by the above-mentioned pressure bonding method.

Next, according to the method for bonding an optical substrate or an electronic substrate of the present invention, the above-mentioned adhesive sheet of the present invention is bonded to the surface of one optical substrate or the electronic substrate to be bonded, and Before or after irradiating the adhesive sheet with light having an active wavelength, the support is peeled off as necessary to expose the adhesive layer, and the other optical substrate or the electron The substrates are bonded together.

In the adhesive method of the present invention, a double-sided adhesive sheet is used among the adhesive sheets of the present invention.

The thickness of the double-sided pressure-sensitive adhesive sheet is not particularly limited, but is preferably 10 to 100 μm. If the thickness of the double-sided adhesive sheet is less than 10 μm, it may not be able to sufficiently follow the unevenness of the optical substrate as the adherend, and conversely, the thickness of the double-sided adhesive sheet may be 100 μm.
When m exceeds m, the thickness as a whole increases, and it may be difficult to reduce the thickness and size of the optical recording medium, or the accuracy in recording or reproducing information may decrease. The thickness accuracy of the double-sided pressure-sensitive adhesive sheet is not particularly limited, but is preferably ± 10% or less, more preferably ± 5% or less with respect to a specified thickness.

The double-sided pressure-sensitive adhesive sheet preferably has the surface of the pressure-sensitive adhesive composition protected by a separator (such as a release film or release paper). Accordingly, it is possible to prevent dust and dust from adhering to the surface of the adhesive composition, and to prevent unnecessary adhesion of the double-sided adhesive sheet to an unnecessary place.

The optical substrate or the electronic substrate used in the bonding method of the present invention is not necessarily required to be transparent. For example, various transparent plastic materials such as acrylic resin, polycarbonate resin, polyester resin, glass epoxy resin, etc. And various dielectric materials such as paper-phenol, glass-phenol, and polyimide. In recent years, with the progress of high durability in substrate applications, many new engineering plastics have been developed,
These new engineering plastic materials may be used.

The optical substrate or electronic substrate used in the bonding method of the present invention includes not only optical disk substrates such as DVDs, LDs and CDs but also magneto-optical disk substrates such as MOs and color filters used for liquid crystal displays. A glass substrate and the like are also included.

Next, the steps of the bonding method of the present invention will be described. First, one surface of the double-sided pressure-sensitive adhesive sheet of the present invention is bonded to one surface of an optical substrate or an electronic substrate to be laminated to be bonded by pressure bonding. When the adhesive composition surface of the double-sided adhesive sheet is protected by the separator, the exposed adhesive composition surface exposed while peeling the separator is attached to the surface of the optical substrate or the electronic substrate to be bonded. to paste together.

Since the double-sided pressure-sensitive adhesive sheet of the present invention has pressure sensitivity, it can be pressure-bonded by applying pressure. The pressing method is not particularly limited, and may be a known method such as a laminating method, a pressing method, or a combination thereof.

The pressure bonding by the lamination method is a pressure bonding method in which an optical substrate or an electronic substrate and a double-sided adhesive sheet are inserted between pressure rollers of a laminating machine provided with two rotating pressure rollers and are continuously pressed. The pressure roller is generally composed of a metal roller such as stainless steel or a rubber roller, and the pressure (lamination pressure) can be controlled by adjusting the gap between the pressure rollers. As the surface material of the rubber roller, NBR,
An elastic material having appropriate hardness, elasticity and releasability, such as ethylene-propylene rubber, ethylene-propylene-diene rubber, silicone rubber, and polytetrafluoroethylene, is used. The hardness and elasticity are appropriately set according to the type of the material to be pressed. In addition, the releasability is adjusted so that the joined body (optical substrate or electronic substrate and double-sided adhesive sheet) that has passed through the roller does not adhere to the roller. Generally, any commercially available laminating machine may be used.

Pressing by a pressing method is a pressing method in which an optical substrate or an electronic substrate and a double-sided pressure-sensitive adhesive sheet are inserted into a metal press plate made of stainless steel, iron, aluminum or the like, and pressure is applied in a batch manner. Although it is possible to perform pressure bonding at a higher pressure as compared with pressure bonding by a lamination method, there is a disadvantage that continuous pressing cannot be performed because of the batch type. In this case, by continuously applying pressure with a belt laminator having a belt-shaped pressing body,
Pressurization equivalent to a batch type can be realized in a continuous process.

In the above pressure bonding, in order to further improve the adhesion between the optical substrate or the electronic substrate and the double-sided pressure-sensitive adhesive sheet, pressure bonding may be performed by pressing after pressing by lamination. Further, by heating the optical substrate or the electronic substrate and the double-sided pressure-sensitive adhesive sheet, the adhesive strength between them may be further improved. Heating may be performed by heating the above-mentioned pressure roller or press plate and indirectly heating the optical substrate or electronic substrate and the double-sided adhesive sheet, or may be performed by heating the optical substrate or electronic substrate and the double-sided adhesive sheet. May be directly heated. In the latter case, infrared rays, electromagnetic waves, hot air, etc. may be applied directly,
A heating plate or the like may be provided at the feeding section of the optical substrate or the electronic substrate and the double-sided adhesive sheet. In the case of heating, it is preferable to set a temperature at which the optical substrate or the electronic substrate is not distorted by heat, and it is preferable to heat at a temperature lower than the thermal deformation temperature of the optical substrate or the electronic substrate.

Further, if the pressure at the time of press bonding is too high, bending distortion or breakage of the optical substrate or the electronic substrate may occur. Therefore, it is preferable to perform pressure bonding at a pressure that does not cause bending distortion or breakage. Specifically, 1.0 MPa (about 1
The pressure is preferably 0 kg / cm ² ) or less.

In the bonding method of the present invention, an autoclave treatment may be performed after the above-mentioned bonding by pressure bonding. The autoclave treatment is a method for removing air bubbles that are trapped between the optical substrate or electronic substrate and the double-sided adhesive sheet in the bonding step.
If air bubbles are involved, the adhesiveness of the portion may be hindered, and further, a bug may occur during recording or reproduction of optical information. It is preferable that the temperature and the pressure in the autoclave treatment are the same conditions as the temperature and the pressure in the pressure bonding step. In addition, the time in the autoclave treatment may be appropriately set according to the amount of air bubbles to be degassed. In general, by performing the treatment for a long time, more air bubbles can be deaerated. In the present invention,
This autoclave treatment is not always necessary and is merely an auxiliary means for deaeration.

After bonding one surface of the double-sided adhesive sheet to one optical substrate or electronic substrate as described above, pass through a separator protecting the other surface of the double-sided adhesive sheet. Irradiation with the above-described light or irradiation with light after peeling off the separator is performed. When the separator is light-transmitting, light may be irradiated through the separator. In this case, radiant heat due to light irradiation is not directly transmitted to the surface of the adhesive composition of the double-sided adhesive sheet, so that a decrease in adhesive strength due to surface curing of the adhesive composition can be suppressed, while light transmission is prevented. It is necessary to lengthen the irradiation time because the rate decreases. In addition, it is necessary to sufficiently consider the thermal characteristics and optical characteristics of the irradiation lamp.

After irradiating the double-sided pressure-sensitive adhesive sheet with light as described above, the other optical substrate or electronic substrate is bonded to the other surface of the double-sided pressure-sensitive adhesive sheet by bonding. The bonding method may be the same as in the case of laminating the first optical substrate or electronic substrate and one surface of the double-sided adhesive sheet (first laminating). When bonding and positioning the substrates before pressing, there is a case where the substrates are compressed by their own weight. In such a case, a large amount of air bubbles may be entrained, resulting in insufficient accuracy during recording or reproduction of optical information, and uneven adhesion, resulting in deterioration of durability. However, since the polyester resin is used in the pressure-sensitive adhesive composition and the double-sided pressure-sensitive adhesive sheet of the present invention, the entrapment of air bubbles can be suppressed. That is, since the polyester resin basically has a linear structure, the mobility of the molecules is high, and since the cohesiveness is low, the tackiness (tack) is small. For sticking, by applying pressure continuously in a linear or concentric manner, it is possible to adhere while expelling bubbles.

In general, curing by cationic polymerization has a low volume shrinkage, but the adhesive composition and the double-sided adhesive sheet of the present invention contain a polyester resin, so that the volume shrinkage is further reduced. . Therefore, deformation distortion caused by the adhesive composition or the double-sided adhesive sheet is reduced, and uniform adhesion between substrates can be achieved.

Through the above steps, the method for bonding an optical substrate or an electronic substrate of the present invention is completed. The laminate of two optical substrates or the laminate of two electronic substrates bonded via the double-sided adhesive sheet is cured with the cation polymerization reaction of the double-sided adhesive sheet over time,
Eventually, it exhibits strong adhesive strength and heat resistance at the adhesive level. In order to further accelerate the curing reaction of the double-sided pressure-sensitive adhesive sheet, heating, humidification, light irradiation, and the like may be additionally performed.

As described above, by bonding an optical substrate or an electronic substrate using a double-sided adhesive sheet based on the bonding method of the present invention, compared with the case of bonding using a conventional liquid adhesive, Undesirable effects on the environment due to the solvent and the curing agent of the adhesive can be suppressed, and the application step is unnecessary, so that the bonding step can be shortened.

In the bonding method of the present invention, since the double-sided adhesive sheet is used, the double-sided adhesive sheet can be processed into a complicated shape. Further, since the adhesive composition constituting the double-sided adhesive sheet has an appropriate cohesive force, it prevents the adhesive composition from sticking out when the optical substrate or the electronic substrate is bonded. I can do it.
Therefore, it is not necessary to cut off the protruding portion or perform masking.

[0080]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight”.

Example 1 (1) Preparation of Adhesive Adhesive Using a homodisper, 70 parts of a polyester resin (trade name “Vylon 550”, manufactured by Toyobo Co., Ltd.), bisphenol A type epoxy resin as an epoxy resin (Product name “Epicoat # 828”, manufactured by Yuka Shell Epoxy) 2
0 parts and alicyclic epoxy resin (trade name “CELLOXIDE 2
081 "(manufactured by Daicel Chemical Industries, Ltd.) and 10 parts of an aromatic sulfonium salt (trade name" ADEKA OPTOMER SP170 ", manufactured by Asahi Denka Kogyo KK) as a cationic photopolymerization initiator are dissolved in 100 parts of methyl ethyl ketone (MEK). The mixture was uniformly stirred and mixed to prepare an adhesive having a solid content of 50% by weight.

(2) Preparation of Adhesive Adhesive Sheet Using a roll coater, the adhesive obtained above was applied to the release-treated surface of a 50 μm-thick PET film (separator) having one surface subjected to release treatment. The composition was coated so that the coating thickness after drying was 30 μm, dried, and then cut to produce a circular non-supported double-sided adhesive sheet having a diameter of 110 mm.

(3) Production of Optical Substrate Assembly A linear pressure of 30 N / cm (about 3 kg /
cm), speed 1 m / min, temperature 23 ° C.
The double-sided pressure-sensitive adhesive sheet obtained above was laminated on one polycarbonate resin substrate (PC substrate) having a light transmittance of 6 mm and a light transmittance of 83%. Next, the separator of the laminated double-sided adhesive sheet was peeled off, and a wavelength of 300 to 400 was applied to the double-sided adhesive sheet surface with a metal halide lamp.
Irradiation was performed for 20 seconds at an illuminance of 50 mW / cm ² . Next, 3 minutes after the irradiation, the other PC substrate (thickness: 0.
(6 mm, 83% light transmittance) on the light-irradiated double-sided pressure-sensitive adhesive sheet surface, and then press concentrically from the center using a hemispherical silicone rubber pad to join a circular optical substrate having a diameter of 110 mm. A body (A) was prepared. In addition, the pressure at the time of pressurization was estimated to be about 0.5 MPa by the prescale in the central part, and was 0.1 MPa in the peripheral part. The optical substrate assembly (A) obtained above is referred to as a “pre-irradiated sample”.

In the production of the optical substrate bonded body, first, one PC substrate and the other PC substrate are bonded via a double-sided adhesive sheet, and then the other PC substrate is passed through to the double-sided adhesive sheet surface. An optical substrate assembly (B) was produced in the same manner as in the case of the optical substrate assembly (A), except that ultraviolet irradiation was performed for 20 seconds so that the illuminance was 50 mW / cm ² . The optical substrate assembly (B) obtained above is referred to as a “post-irradiation sample”.

(4) Evaluation The performance (gel fraction, thickness accuracy) of the adhesive obtained above and the performance (deformation resistance, tensile adhesion, heat resistance, Whether or not bubbles are involved)
Was evaluated by the following method. The results were as shown in Table 1.

Gel fraction: One side of a 50 μm-thick PET film (separator) with release treatment applied on one side was coated with a pressure-sensitive adhesive on the release-treated surface so that the coating thickness after drying was 30 μm. After processing and drying, the same separator was coated on the same release-treated surface, and the other adhesive was irradiated with ultraviolet rays to cure the adhesive. Then, under an atmosphere of 23 ° C., the film of the adhesive agent irradiated with the ultraviolet rays was immersed in ethyl acetate for 24 hours, and then filtered through a 200-mesh stainless steel mesh. Then, the weight was measured, and the ratio to the initial weight of the adhesive film was calculated to determine the gel fraction. In addition, the gel fraction was determined for both the adhesive film and the adhesive film after 1 hour and 10 days after ultraviolet irradiation.

Thickness accuracy: After irradiating the adhesive with ultraviolet rays in the same manner as in the case of above, the adhesive was left to cure in an atmosphere of 23 ° C. for 10 days. Next, before the coated separator was peeled off, the thickness was measured with a thickness gauge, and the value obtained by subtracting the thickness of the separator was defined as the thickness of the adhesive layer. The measurement was carried out at arbitrary 20 points selected at random, and the deviation (σ) of this numerical value was defined as the thickness accuracy. It can be said that the smaller the deviation (σ), the higher the thickness accuracy.

Deformation resistance: The bonded optical substrate immediately after bonding was punched into a circular shape having a diameter of 100 mm using a punching machine to prepare a sample for measurement. Next, the obtained measurement sample was
After leaving for 1 hour and 10 days in an atmosphere of 3 ° C, 40
Exposure was performed for 1 day in a humidified oven at -90% RH, and the amount of warpage was measured. The amount of warpage was calculated by "maximum height-thickness of measurement sample" when the measurement sample was placed on a horizontal surface plate.
It can be said that the smaller the amount of warpage, the better the deformation resistance.
The evaluation of deformation resistance was performed for both the pre-irradiated sample and the post-irradiated sample.

Tensile adhesive strength: The optical substrate assembly was left in an atmosphere of 23 ° C. for 10 days, cut into 1 cm squares,
A measurement sample was prepared. Next, using two T-shaped jigs, the horizontal surface of the upper and lower two jigs and the front and back of the measurement sample are bonded with a two-component urethane-based adhesive, and the vertical surfaces of the jigs are fixed with clamps. , Peeling speed 10 mm / min, Measurement temperature 23 ° C
Was used to measure the tensile adhesive strength. The evaluation of the tensile adhesion was performed for both the pre-irradiated sample and the post-irradiated sample.

Heat resistance: The optical substrate assembly was left in an atmosphere at 120 ° C. for one day, taken out, and visually observed for the appearance to determine the presence or absence of delamination. The heat resistance was evaluated for both the pre-irradiated sample and the post-irradiated sample.

After the measurement sample prepared in accordance with the presence or absence of bubbles was left in an atmosphere at 23 ° C. for 10 days, the appearance was visually observed to determine the presence or absence of bubbles. The evaluation of the presence or absence of air bubble entrapment was performed for both the pre-irradiated sample and the post-irradiated sample.

Example 2 The composition of the adhesive was changed to a polyester resin (trade name “Byron 200”, manufactured by Toyobo Co., Ltd.).
50 parts, 20 parts of bisphenol A type epoxy resin “Epicoat # 828”, 30 parts of alicyclic epoxy resin “Celoxide 2081”, 0.5 parts of photocationic polymerization initiator “Adeka Optomer SP170” and 100 parts of MEK Other than the above, the adhesive and the adhesive were the same as in the case of Example 1,
An adhesive sheet and a bonded optical substrate (a pre-irradiated sample and a post-irradiated sample) were obtained.

Comparative Example 1 The composition of the adhesive was 70 parts polyester resin “Vylon 550”, bisphenol A
Adhesive and adhesive in the same manner as in Example 1, except that 30 parts of the epoxy resin “Epicoat # 828”, 1 part of the cationic photopolymerization initiator “Adeka Optomer SP170” and 100 parts of MEK were used. A sheet and an optical substrate assembly (post-irradiation sample) were obtained.

Comparative Example 2 As a pressure-sensitive adhesive, 40 parts of butyl methacrylate monomer, 30 parts of ethyl acrylate monomer, 30 parts of 1,6-hexanediol dimethacrylate, and a photo-radical polymerization initiator (trade name "Ricillin T")
PO ", manufactured by BASF Co., Ltd.).

The adhesive obtained above was applied on one of the PC boards in the same manner as in Example 1 by a spin coating method so that the applied thickness was 30 μm and the adhesive area was a circle having a diameter of 110 mm. did. Next, the other PC substrate similar to that in the case of Example 1 was laminated, degassed by reducing the pressure to 500 hPa, and then the wavelength was 300 to 400 nm using a metal halide lamp.
Was irradiated for 20 seconds to cure the adhesive, thereby obtaining an optical substrate assembly (post-irradiated sample).

Comparative Example 3 As an adhesive, 99.92 parts of a copolymer (weight average molecular weight: 500,000) of 98 parts of butyl acrylate monomer and 2 parts of acrylic acid, and an epoxy-based crosslinking agent (trade name “TETRAD”) -X "(manufactured by Mitsubishi Gas Chemical Company) using an acrylic adhesive consisting of 0.08 parts and 100 parts of MEK, in the same manner as in Example 1 except that ultraviolet irradiation was not performed. A sheet and an optical substrate assembly were obtained.

The performances of the adhesive and optical substrate assembly obtained in Example 2 and Comparative Examples 1 to 3 were evaluated in the same manner as in Example 1. The results are shown in Table 1. In addition, about the thickness accuracy of the adhesive of Comparative Example 3, the thickness of the adhesive sheet on a separator was measured directly with the thickness gauge. The optical substrate joined bodies of Comparative Example 2 and Comparative Example 3 are described as post-irradiation samples for convenience, although there is no distinction between pre-irradiation and post-irradiation.

[0098]

[Table 1]

[0099]

As described above, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition of the present invention has excellent tackiness and initial tackiness at room temperature before curing, and the It cures by irradiating light before or after lamination and exhibits sufficient cohesive force after curing, so it can suppress warpage and deformation of plastic substrates used as optical substrates and electronic substrates, for example, and is excellent. Expresses adhesive strength and heat resistance.

Further, according to the bonding method of the present invention using the above-mentioned pressure-sensitive adhesive sheet, it is possible to easily obtain an optical substrate bonded body and an electronic substrate bonded body having the above-mentioned excellent various performances.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) G11B 7/26 G11B 7/26 // B29K 63:00 B29K 63:00 67:00 67:00 B29L 7: 00 B29L 7:00 F term (reference) 4F211 AA24 AA28 AA39 AB04 AD04 AD08 AD32 AG01 AG03 AH37 AH38 TA03 TA05 TC02 TD11 TH24 TJ31 TN45 TN46 TN56 TQ04 4J004 AA13 AA15 AA17 AB07 CA02 CA04 CA05 CA02 CC04 DA03 FA03 EC061 EC062 EC071 EC072 EC091 EC092 EC121 EC122 EC231 EC232 EC261 EC262 EC361 EC362 EC401 EC402 EC411 EC412 ED031 ED032 JA09 JB08 KA13 LA06 LA08 MA10 MB03 NA17 NA19 PA23 PA32 5D121 AA07 FF03 GG02

Claims (3)

[Claims] 1. A polyester resin 40 in the total resin composition.
90 to 90% by weight, an epoxy resin in an amount of 10 to 60% by weight, and an effective amount of a cationic photopolymerization initiator.
A curable adhesive composition comprising 90% by weight. 2. A curable adhesive sheet comprising the support and the curable adhesive composition according to claim 1 laminated on at least one surface of the support. 3. The curable adhesive sheet according to claim 2 is attached to a surface of one of the optical substrate and the electronic substrate to be adhered, and light having an active wavelength is applied to the adhesive sheet. Before or after irradiation, if necessary, the support is peeled off to expose the adhesive layer, and the other optical substrate or electronic substrate is bonded onto the adhesive sheet and bonded. Bonding method of an optical substrate or an electronic substrate.