JP2019077877A - Adhesive resin layer, adhesive resin film, laminate and method for producing laminate - Google Patents

Abstract

To provide an adhesive resin layer which can prevent occurrence of air bubbles even when being stuck onto a base material having a high step and can maintain transparency, a laminate and a method for producing the laminate.SOLUTION: An adhesive resin layer 11 of a single layer is formed of an acrylic adhesive resin composition having transparency, in which the adhesive resin composition contains 100 pts.wt. of an acrylic polymer, 4-20 pts.wt. of 4-hydroxy butylacrylate as an acrylic monomer, 0.001-5 pts.wt. of a thermal polymerization initiator and a crosslinking agent in an amount of 1.5 equivalent or more with respect to the acrylic polymer, the thermal polymerization initiator is a peroxide, the crosslinking agent is a crosslinking agent selected from an isocyanate crosslinking agent, an epoxy crosslinking agent and a metal chelate compound, and the adhesive resin layer 11 has adhesiveness on both surfaces at ordinary temperature and can be thermally cured by heating at a temperature of 100-250°C for 30 seconds to 10 minutes.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive resin layer, an adhesive resin film, a laminate, and a method for producing a laminate, which can prevent the generation of air bubbles even when they are bonded to a substrate having a step.

  A pressure-sensitive adhesive is widely used in order to laminate and bond substrates having transparency or transparency, such as touch panels, mobile phones, displays, and laminated glass. The surface of the substrate may have a step due to the printing layer, the wiring, the electrode, the frame, and the like. When the pressure-sensitive adhesive is laminated on a substrate having a level difference, a void may be generated between the level difference and the pressure-sensitive adhesive, and if air bubbles remain, adhesion strength between the substrates and optical properties through the substrate may be deteriorated. is there.

  Patent Document 1 discloses a hard coat layer, a transparent group as a pressure sensitive adhesive sheet for a protective film which is suitable for use as a panel protective film of a portable information terminal such as a mobile phone or a touch panel, in particular for a glass panel. There is disclosed a pressure-sensitive adhesive sheet for a protective film, in which a material film, an adhesive layer, a polyester film, a pressure-sensitive adhesive layer and a release sheet are sequentially laminated. However, the pressure-sensitive adhesive sheet for a protective film has a complicated layer structure and is expensive, and the elastic force of the resin film makes it difficult to follow the high level difference, and air bubbles are introduced.

  Patent Document 2 describes a pressure-sensitive adhesive sheet produced by photopolymerizing an acrylic resin composition containing a photo radical polymerization initiator on a release sheet as a pressure-sensitive adhesive sheet used for adhesive applications of optical members. ing. However, Patent Document 2 does not mention the prevention of air bubbles with respect to steps.

Patent Document 3 describes the following two embodiments as a method of manufacturing a touch panel without generating air bubbles or the like.
First Embodiment After a UV curable resin or a thermosetting resin is applied to the surface of the touch panel main body on which the print layer is formed, a step of forming a resin layer by UV irradiation or heating, and a cover film The manufacturing method which has the process of affixing the surface where the transparent adhesive sheet for optics is stretched to the surface in which the resin layer of the touch-panel main-body part is formed.
Second Embodiment The step of applying an ultraviolet curable resin to the surface of the touch panel main body on which the print layer is formed, the step of placing a cover film on the ultraviolet curable resin, and the subsequent irradiation of ultraviolet rays Manufacturing method having a step of
However, in the case of the first embodiment, it is necessary to form a resin layer for each substrate, and the number of processes increases. In addition, in the case of the second embodiment, since it is necessary to provide equipment for ultraviolet irradiation that adversely affects the human body, and it is necessary to irradiate ultraviolet light all over the resin layer, if there is an opaque portion on the substrate, photocuring Will be inadequate.

  Patent Document 4 describes, as an acrylic pressure-sensitive adhesive used in a touch panel, a pressure-sensitive adhesive containing a main polymer having a crosslinkable functional group, a low molecular weight polymer having a hydrogen bondable functional group, and an isocyanate-based crosslinking agent. It is done. Patent Document 4 describes that, as an effect, the variation in the electrical characteristics of the transparent conductive film is small, and the heat and moisture stability and the step followability are good, and whitening and foaming are less likely to occur. It is difficult to follow up and bubbles will enter.

JP, 2012-35431, A JP, 2013-166846, A JP 2014-26337 A JP, 2013-1769, A

  The present invention has been made in view of the above circumstances, and it is possible to prevent the generation of air bubbles even when pasted on a substrate having a high level difference, and a laminate of a substrate / adhesive resin layer / substrate Adhesive resin layer, adhesive resin film, laminate, and laminate that can maintain transparency without bubbles being generated even after heat endurance and after wet heat endurance. An object is to provide a method of manufacturing a body.

  In order to solve the said subject, this invention is a single-layer adhesive resin layer which consists of an acrylic adhesive resin composition which has transparency, Comprising: The said adhesive resin composition is (A) acrylic polymer. And (B) an acrylic monomer and (C) a thermal polymerization initiator, and the adhesive resin layer has adhesiveness on both sides at normal temperature, and a temperature of 100 to 250 ° C. and 30 seconds to 10 An adhesive resin layer is provided, which can be thermally cured by heating for a minute time.

It is preferable that the said acryl-type monomer is a monomer of the (meth) acrylate which has a hydroxyl group.
The adhesive resin composition preferably contains 4 to 20 parts by weight of the (B) acrylic monomer with respect to 100 parts by weight of the (A) acrylic polymer.
It is preferable that the said thermal-polymerization initiator is a peroxide.
In the adhesive resin layer, the storage elastic modulus at a temperature of 23 ° C. after heat curing is higher than the storage elastic modulus at a temperature of 23 ° C. before heating, and the storage elastic modulus at a temperature of 23 ° C. before the heating Is preferably 1 × 10 ⁴ to 1 × 10 ⁶ Pa, and the storage elastic modulus at a temperature of 23 ° C. after thermosetting by heating is preferably 1 × 10 ⁴ to 1 × 10 ⁹ Pa.

The present invention also provides an adhesive resin film characterized in that the adhesive resin layer is laminated between two separators.
The present invention also provides a laminate comprising two sheets of substrates laminated via the adhesive resin layer.

  Moreover, this invention heat-cures the said adhesive resin layer in the state which laminated | stacked two base materials via the adhesive resin layer, and pinched | interposed the obtained laminated body between two metal molds. The invention provides a method of manufacturing a laminate characterized by:

The solvent contained in the raw material composition of the adhesive resin layer is at a temperature A, the temperature at which the thermal polymerization initiator has a half life of one minute is a temperature B, and the solvent is removed in the process for producing the adhesive resin layer Assuming that the temperature at the time of heating is temperature C, and the pressing temperature of the mold in the step of heat curing the adhesive resin layer is temperature D, each temperature is preferably in the order of the following formula (1).
Formula (1) temperature A <temperature C <temperature B <temperature D

At least one base material of the two base materials may include a step of 5 μm to 1 mm in the surface on the side in contact with the adhesive resin layer.
The step may include a step of 50 μm to 1 mm.
The adhesive resin layer of the present invention is preferably thicker than the step. The thickness of the adhesive resin layer of the present invention is preferably 55 μm to 3 mm, which is 1.1 to 3 times the level difference, and more preferably 60 μm to 2 mm, which is 1.2 to 2 times the thickness of the level difference.
It is preferable that the temperature of the mold at the time of the heat curing be a temperature of 150 to 300 ° C.

  The present invention is characterized by containing an acrylic polymer, an acrylic monomer, and a thermal polymerization initiator, and an adhesive resin layer in the form of a transfer tape can be produced from the above components. The adhesive resin layer has a substrate following property to a substrate having a level difference due to the monomer component. It is possible to provide an adhesive resin layer in which air bubbles do not enter even if a monomer component is cured by reaction initiation conditions such as heat and there is a level difference, and a method for producing the same. In particular, by devising the addition amount of the acrylic monomer, it is possible to maintain the followability to the base material and the strength of the adhesive resin layer itself in the form of a transfer tape. According to the present invention, it has become possible to force the adhesive resin layer to follow the substrate semi-forcefully, in particular by heat pressing. During the manufacture of laminates, the heat press that applies both heat and pressure to the laminate without air, rather than curing by electron beam irradiation via air or energy beam irradiation, suppresses air bubble generation and durability. It is preferable from the viewpoint.

  ADVANTAGE OF THE INVENTION According to this invention, even if it bonds to the base material which has a high level | step difference, generation | occurrence | production of air bubbles can be prevented and the adhesive resin layer which can maintain transparency, an adhesive resin film, a laminated body, A method of manufacturing a laminate can be provided.

It is sectional drawing which shows an example of the adhesive resin film of this invention. It is sectional drawing which shows an example of the base material which has a level | step difference. It is sectional drawing which shows an example of the laminated body by which the adhesive resin layer was laminated | stacked between two base materials. It is sectional drawing which shows an example of the state which clamped the laminated body of FIG. 3 between metal mold | dies. It is sectional drawing which shows an example of the laminated body by which the adhesive resin layer was heat-hardened.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.
FIG. 1 shows a cross-sectional view of an example of the adhesive resin film 10. The adhesive resin film 10 has two separators 12 and 13 and an adhesive resin layer 11 laminated between them. The adhesive resin composition constituting the adhesive resin layer 11 contains (A) an acrylic polymer, (B) an acrylic monomer, and (C) a thermal polymerization initiator. Both surfaces 11a and 11b of the adhesive resin layer 11 have adhesiveness (it becomes an adhesive surface) at normal temperature.

  The adhesive resin layer 11 consists of an adhesive resin composition over the thickness direction. If it consists of an adhesive resin composition which fulfills requirements, adhesive resin layer 11 may be constituted from two or more layers which consist of adhesive resin compositions of the same kind or a different kind. When the adhesive resin layer 11 consists of a single layer adhesive resin layer, it is preferable because the layer structure can be simplified and the cost can be reduced. The adhesive resin composition contains an acrylic adhesive resin (polymer) and has transparency.

  The separators 12 and 13 have releasability on the surfaces 12 a and 13 a on the side in contact with the adhesive resin layer 11 (the releasable surface). As a structure of the separators 12 and 13, the structure which provided the release agent layer in the single side | surface or both surfaces of a resin film, and the structure which contains a release agent in resin of a resin film are mentioned. Instead of the resin film, paper, synthetic paper, metal foil, various sheets and the like can also be used. When the separators 12 and 13 have transparency, it is preferable because the optical inspection of the adhesive resin layer 11 can be performed with the adhesive resin film 10 in which the separators 12 and 13 are not peeled off.

  The adhesive resin film 10 shown in FIG. 1 can bond two base materials by the adhesive surfaces 11a and 11b exposed by peeling the separators 12 and 13 from the adhesive resin layer 11. An example of the laminated body 20 in which the adhesive resin layer 11 was laminated | stacked between the base materials 21 and 22 of 2 sheets in FIG. 3 is shown. As shown in FIG. 2, at least one of the two substrates 21 and 22 (here, the substrate 21) has a step due to the convex portion 23. The step due to the convex portion 23 may be present on one side of the surfaces 21 a and 22 a on the side where the two substrates 21 and 22 are in contact with the adhesive resin layer 11 or may be present on both sides.

  In FIG. 2, the convex portion 23 is illustrated separately from the base material 21, but the convex portion 23 may be integral with the base material 21. For example, when the unevenness is formed on the surface of the base material, a step (height difference) between the bottom of the recess and the top of the protrusion is a step. The level difference provided on the surfaces 21a and 22a on the side in contact with the adhesive resin layer 11 may be a combination of large and small, but may include a level difference of 5 μm to 1 mm. Furthermore, a 50 μm to 1 mm step may be included.

  The substrates 21 and 22 are adherends bonded by the adhesive resin layer 11. Each of the substrates 21 and 22 may be a rigid plate or may be flexible like a film. For example, it may be a single plate of glass, polycarbonate, acryl, various resins, ceramics, metals or the like, or may be a composite made of a plurality of materials such as a liquid crystal panel, a touch panel, a cover glass, and a wiring board. The outer surfaces 21 b and 22 b of the substrates 21 and 22 may be flat or may have irregularities.

  When forming the laminated body 20 like FIG. 3, the order which peels the separators 12 and 13 is not specifically limited. After one substrate is bonded to one adhesive surface exposed by peeling one separator, the other substrate is bonded to the other adhesive surface exposed by peeling the other separator. May be After peeling off both separators and exposing both adhesive surfaces, the substrates may be bonded to each other.

  Since the adhesive resin layer 11 contains the (B) acrylic monomer having fluidity, it has high flexibility and can be wetted with the adhesive resin composition up to the corner 24 of the step of the convex portion 23. Therefore, air bubbles can be suppressed even if the step is large. Since the adhesive resin layer 11 contains (C) a thermal polymerization initiator, bonding can be further strengthened by heat curing after bonding. As compared with ultraviolet light irradiation, the equipment for heat curing is simple, and there is an advantage that the substrate can be reliably cured even when it contains a low light transmitting portion.

  The laminated body 20 obtained by laminating the two base materials 21 and 22 via the adhesive resin layer 11 is heated in a state of being held between the two molds 31 and 32, as shown in FIG. By doing this, the adhesive resin layer 11 can be cured. As a result, the reaction (polymerization, crosslinking, etc.) of (A) acrylic polymer and (B) acrylic monomer progresses, and the adhesion between the substrates 21 and 22 is increased. Moreover, by pressurizing with heating, even if air bubbles remain around the step, the air gaps can be filled and the air bubbles can be removed. At the time of heat curing, at least one of the molds 31 and 32 is heated.

  When the laminated body 20 is heat-pressed, between the molds 31 and 32 and the laminated body 20 (specifically, between the pressing surfaces 31 a and 32 a of the molds 31 and 32 and the outer surfaces 21 b and 22 b of the base members 21 and 22) A cushion (buffer sheet), a release sheet, a protective sheet or the like (inclusion) may be interposed. In the case where the outer surfaces 21 b and 22 b of the base members 21 and 22 have unevenness, the pressure tends to be concentrated on the projections when the projections on the outer surface directly contact the molds 31 and 32. preferable.

  Although the molds 31 and 32 do not cover the side surface of the laminate 20 in FIG. 4, one or both of the molds 31 and 32 are provided with asperities so that the side surfaces of the laminate 20 are covered by the molds. It may be configured. For example, one mold may be a convex mold, and the other mold may be a concave mold, and after the laminate 20 is accommodated in the concave concave, the convex convex may be approached toward the concave concave.

  FIG. 5 shows an example of a laminate 30 obtained by heat curing. In the laminate 30, as a result of the thermosetting of the adhesive resin layer 11, the adhesive layer 25 made of the adhesive resin which is thermally cured is laminated between the two substrates 21 and 22. The hardness of the adhesive layer 25 after the heat curing is increased, so that the adhesive resin layer 11 before heating is difficult to be peeled off even if it is flexible. Thus, as the adhesive resin layer 11, a resin having excellent step followability can be used even if the adhesive power is low.

  When manufacturing the layered product 30, when, for example, the base 21 has irregularities and the base 22 is flat, several manufacturing methods can be considered. Any method can be adopted for manufacturing the laminate 30.

As a first laminating method, the adhesive resin layer 11 is laminated on the base material 21 having the unevenness, and then the autoclave treatment is carried out, and the flat base material 22 is laminated on the adhesive resin layer 11 to form a laminate. After laminating 20 or while laminating the base material 22, there is a method of heating and curing the adhesive resin layer 11 using the molds 31 and 32.
As a second laminating method, after the adhesive resin layer 11 is laminated on the flat base material 22 and then autoclaved, and the base material 21 having the unevenness is laminated on the adhesive resin layer 11, Alternatively, there is a method of heating and curing the adhesive resin layer 11 using the molds 31 and 32 while laminating the base material 21.
As a third laminating method, after simultaneously or simultaneously laminating the base 21 having the unevenness, the adhesive resin layer 11 and the flat base 22, the adhesive resin layer 11 is formed using the molds 31 and 32. And heat curing.

  In the first laminating method, the adhesive resin layer easily follows the irregularities by laminating the substrate 21 having the irregularities and the adhesive resin layer 11 first and performing the autoclave treatment, so that the heat press is performed. This is a method that can reduce air bubbles even if the processing conditions are widely dispersed. The third lamination method is the most cost-effective method in that the manufacturing process can be shortened.

  In FIG. 2 to FIG. 5, the steps of the substrates 21 and 22 are provided on the substrate in advance before the hot pressing, but when laminating the adhesive resin layer 11 between the substrates 21 and 22 and performing the heat pressing It is also possible to deform one or both of the substrates 21 and 22 to generate a step. For example, when the pressing surfaces 31a and 32a of the molds 31 and 32 are uneven, the flexible substrates 21 and 22 such as resin films can be deformed. The flowability of the initial adhesive resin layer 11 makes it possible to follow the steps of the substrates 21 and 22. In addition, during the heat press, the thermal polymerization proceeds to harden the adhesive resin layer 11, and it is possible to suppress the generation of voids or air bubbles. Furthermore, since the substrates 21 and 22 are joined to the adhesive layer 25, the deformation of the substrate is fixed and the formation of the unevenness can be realized. When a convex part is formed in the inner surface of a substrate, a crevice may be formed in the external surface of the back side.

  In order to improve the handleability of the adhesive resin layer 11, the adhesive resin layer 11 is preferably thermally cured by heating at a temperature of 100 to 250 ° C. and for a time of 30 seconds to 10 minutes. It is preferable to thermally cure at least a part of these temperature and time ranges, and more preferable to be thermally curable in the entire range. The thermosetting conditions at the time of actual use may be outside the above range. However, from the viewpoint of storage stability, it is preferable that thermal curing does not substantially progress at normal temperature, and for example, at a temperature of 100 ° C. or less, it is preferable to have the property that thermal curing does not occur by heating for 10 minutes or less.

When the adhesive resin layer 11 is in an uncured state (before heating), the storage elastic modulus at a temperature of 23 ° C. is preferably 1 × 10 ⁴ to 1 × 10 ⁶ Pa. Moreover, after the adhesive resin layer 11 is thermally cured by heating, it is preferable that the storage elastic modulus at a temperature of 23 ° C. is 1 × 10 ⁴ to 1 × 10 ⁹ Pa. The storage elastic modulus at a temperature of 23 ° C. after heat curing by heating is preferably higher than the storage elastic modulus at a temperature of 23 ° C. before heating. The storage elastic modulus of these adhesive resin layers in the uncured state (before heating) and the adhesive resin layer after heat curing by heating (the adhesive layer after heat curing) are each set to a temperature of 23 ° C. It can be measured. The vibration frequency at the time of measuring a storage elastic modulus is 1 Hz, for example. When measuring the storage elastic modulus of the adhesive layer after heat curing, the adhesive resin layer is heated and cured between the separator films without bonding the adhesive resin layer to the substrate, and then the separator film is peeled off. As a result, the adhesive layer after heat curing can be obtained alone.

Next, the adhesive resin layer which is also a transfer tape will be described in more detail.
The adhesive raw material composition used for the production of the adhesive resin layer of the present invention preferably contains an organic solvent because it can be applied with higher thickness when it is dissolved in the organic solvent. The adhesive resin layer is obtained by drying the solvent from the adhesive raw material composition. That is, the composition of the adhesive raw material composition may be one obtained by adding a solvent to the composition of the adhesive resin composition constituting the adhesive resin layer. The adhesive resin layer can function as an adhesive layer at normal temperature (before thermosetting).

(A) A monomer constituting an acrylic polymer is an acrylic monomer having an ester group (-COO-), an acrylic monomer having a carboxyl group (-COOH), an amide group (-CONR ₂ , R is a hydrogen atom or an alkyl And acrylic monomers having a nitrile group (-CN), olefins, styrene, vinyl esters, vinyl ethers, non-acrylic monomers such as vinyl silanes, and the like. The (A) acrylic polymer is preferably a copolymer composed of two or more monomers. The number average molecular weight of the (A) acrylic polymer before photopolymerization is preferably, for example, about 5 to 100,000. The viscosity is, for example, about 1000 to 10000 mPa · s.

  As an acrylic monomer having an ester group (-COO-), an alkyl (meth) acrylate, a (meth) acrylate having a hydroxyl group (hydroxy group), a (meth) acrylate having an alkoxy group or a polyether group, an amino group or a substituted group The (meth) acrylate etc. which have an amino group are mentioned. In the present specification, (meth) acrylate is a generic term for acrylate and methacrylate.

Examples of acrylic monomers having a carboxyl group (-COOH) include acrylic acid, methacrylic acid, (meth) acrylates having a carboxyl group (-COOH), and the like.
Amide group (-CONR 2, _R is a substituent such as a hydrogen atom or an alkyl group) acrylic monomer having, acrylamide, methacrylamide.
Acrylonitrile, methacrylonitrile, etc. are mentioned as an acryl-type monomer which has a nitrile group (-CN).

In the acrylic polymer (A), it is preferable that 50% by weight or more of the constituent monomers consist of the acrylic monomer. In particular, 50% by weight or more of the constituent monomers are represented by the general formula CH ₂ CRCR ¹ —COOR ² (wherein, R ¹ represents hydrogen or a methyl group, and R ² represents an alkyl group having 1 to 14 carbon atoms). It is preferable that it consists of 1 type (s) or 2 or more types of the alkyl (meth) acrylate to be. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate and isobutyl (meth) acrylate , T-butyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate ) Acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate. In particular, it is preferable to use an alkyl (meth) acrylate having 4 to 12 carbon atoms as the essential component (for example, 50 to 100 mol%) of the alkyl group R ² .

  Moreover, as (meth) acrylate containing a hydroxyl group, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) Acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxy octane (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, cyclohexane dimethanol mono (meth) acrylate, etc. 1 or 2 There are more species.

  (B) As an acryl-type monomer, the monomer similar to the monomer which comprises (A) acryl-type polymer is mentioned. However, the same monomer as one or two or more of the monomers constituting (A) acrylic polymer is not necessarily used as one or two or more of (B) acrylic monomers, and they are different from each other It may be a monomer.

  The (B) acrylic monomer is not particularly limited as long as it becomes a part of a polymer by thermal curing with a (C) thermal polymerization initiator and is a liquid (fluid) having a viscosity lower than that of the polymer. (B) As an acryl-type monomer, acrylate oligomers, such as a urethane acrylate oligomer and an epoxy acrylate oligomer, can also be used. The number of polymerizable functional groups that the (B) acrylic monomer has is, for example, 1 to 5.

  When a (meth) acrylate monomer having a hydroxyl group is contained as part or all of the (B) acrylic monomer, the polar hydroxyl group is likely to be dispersed in the entire adhesive resin layer. Thereby, even in a high humidity (high temperature) environment, water is difficult to be aggregated, and white turbidity of the adhesive resin layer is suppressed, which is preferable.

  (C) As a thermal polymerization initiator, the radical initiator which decomposes | disassembles by heat and starts superposition | polymerization (radical polymerization) of a monomer and hardening of resin is mentioned. As radical initiators, redox initiators that act at low temperatures, organic metal compounds, etc. are also known, but in terms of the handleability of the adhesive resin layer, (organic) peroxides that act at higher temperatures, Azo-based ones are preferred. Thermal polymerization initiator is a temperature at which the half life of the thermal polymerization initiator becomes 1 minute in order to prevent reaction or half in the process of manufacturing the transfer tape, particularly in the drying process of the solvent (hereinafter “one minute half life temperature” Is sometimes higher than the boiling point of the organic solvent contained in the adhesive raw material composition. The thermal polymerization initiator is preferably a material having a one-minute half-life temperature that is 50 ° C. or more lower than the heat press set temperature, in order to cause the reaction at a temperature during heat press to sufficiently react for a certain time.

  Specific examples of (organic) peroxide-based thermal polymerization initiators include benzoyl peroxide, acetyl peroxide, decanoyl peroxide, lauroyl peroxide, dicumyl peroxide, di-t-butyl peroxide, and t-butyl peroxybenzoate , T-butylperoxy-2-ethylhexanoate, cumene hydroperoxide, t-butyl hydroperoxide and the like.

  As an azo thermal polymerization initiator, 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethyl) Valeronitrile), 2,2'-azobis (4-cyanovaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (methyl isobutyrate) And 1,1′-azobis (1-cyclohexanecarbonitrile) and the like.

  A polymerization retarder can be added to the adhesive resin layer of the present invention. The use of a polymerization retarder facilitates control of the degree of polymerization. Moreover, it is preferable from the viewpoint of improving the step followability.

  The adhesive resin composition contains (B) 4 to 20 parts by weight of an acrylic monomer and (C) 0.001 to 5 parts by weight of a thermal polymerization initiator with respect to 100 parts by weight of (A) an acrylic polymer. Is preferred.

  The adhesive resin composition can further contain optional components other than (A) to (C). For example, (D) crosslinking agents (curing agents) such as isocyanate crosslinking agents, epoxy crosslinking agents, metal chelate compounds, etc. can produce (A) acrylic polymers or (B) polymers produced by polymerization of acrylic monomers. It is suitably used for crosslinking. In this case, if necessary, as at least a part of the (A) acrylic polymer or (B) acrylic monomer, a polymer or a monomer having a functional group that reacts with the (D) crosslinking agent is used. The functional group that reacts with the crosslinking agent (D) is, for example, a hydroxyl group or a carboxyl group in the case of an isocyanate crosslinking agent. The amount of the crosslinking agent (D) added is preferably, for example, 1.5 equivalents or less with respect to the functional group of the polymer. Other optional components include, for example, antioxidants, fillers, plasticizers and the like. The adhesive raw material composition used for producing the adhesive resin layer may contain a solvent such as water or an organic solvent, or may be a solventless syrupy composition. When there is a material which may be corroded such as an oxide conductive film such as ITO or a base metal on the substrate and the adhesive resin layer comes in contact with it, corrosion of acid or the like as a material of the adhesive resin composition It is preferable to reduce the sex component and use, for example, a polymer having a low acid value.

(Method of producing adhesive resin layer)
The adhesive resin layer (transfer tape) in the present invention can be produced by applying an adhesive raw material composition to a separator film in a state containing a solvent, drying it, and further protecting it by the separator film. The adhesive raw material composition is preferably applied using a die or a pipe doctor. In drying of the solvent, it is preferable to dry with a drier or the like. Regarding the drying time of the solvent, in consideration of productivity, it is preferably 10 minutes or less, and more preferably 2 to 5 minutes. Further, since it is necessary to sufficiently dry the organic solvent, it is preferable to dry at a temperature higher than the boiling point of the organic solvent, and it is preferable to dry the thermal polymerization initiator at a half-life temperature or less.

  Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  The laminate may have an adhesive resin layer between three or more substrates. It is preferable that one or more (preferably all) of the two or more adhesive resin layers contained in the laminate is the adhesive resin layer of the present embodiment.

  When the laminate is hot pressed, two or more laminates may be disposed between a pair of molds. This arrangement is not particularly limited, and two or more laminates may be stacked in the compression direction by the mold, or two or more laminates in a plane perpendicular to the compression direction (for example, on the pressing surface of any of the molds) You may arrange them. The above-mentioned inclusion may be interposed between two or more laminates.

  In the present invention, after the production of the adhesive resin layer 11 as shown in FIG. 1, a laminated structure as shown in FIG. 3 is produced, and heat treatment is carried out with the configuration as shown in FIG. In the production of the adhesive resin layer 11 of FIG. 1, it is preferable to provide a step of removing the solvent by heating from the adhesive raw material composition containing the solvent. Moreover, in the process conditions after the subsequent bonding, it is necessary to heat the adhesive resin layer 11 to start polymerization.

(Press conditions)
In the press of the present invention, in order to apply heat to the laminate at a heating temperature of 100 to 250 ° C., it is necessary to heat the mold at a temperature higher than the desired heating temperature. The temperature of the mold is preferably 100 to 300 ° C, more preferably 150 to 300 ° C. If the base material or part of the base material contains polyethylene terephthalate, and the polyethylene terephthalate is heated at, for example, 180 ° C. for about 10 minutes, the oligomer component precipitates, and if the precipitated component causes appearance defects, heat press It is preferable to set the heating temperature at 180 ° C. or less.
When a base material does not contain polyethylene terephthalate and does not have precipitation of an oligomer component, it may be 100 to 300 ° C. With regard to the pressing time in the present invention, it is preferable from the viewpoint of productivity that the reaction is completed within 2 minutes. In addition, the press temperature and time can be set so that the strength of the laminate is sufficient.

  Hereinafter, the present invention will be specifically described by way of examples.

Example 1
(A) As an acrylic polymer, SK dyne (registered trademark) 2094 (SOKEN CHEMICAL CO., LTD., Acid value: 33, number average molecular weight 70,000), E-AX (SOKEN CHEMICAL CO., LTD.) As a crosslinking agent, solid polymer It was mix | blended in the ratio of 0.05 weight part of crosslinking agents with respect to 100 weight part of parts. In the obtained mixture, 10 parts by weight of 4-hydroxybutyl acrylate (Osaka Organic Chemical Industry Co., Ltd .; 4 HBA) as an (B) acrylic monomer, and t-butylperoxy-2- as a (C) thermal polymerization initiator. An adhesive raw material composition was prepared by adding 0.02 parts by weight of ethyl hexanoate (manufactured by NOF Corporation; product name: Perbutyl (registered trademark) O). The adhesive raw material composition contains ethyl acetate (boiling point 77 ° C.) as a solvent.
The adhesive raw material composition was applied to the upper surface of a separator (manufactured by Fujimori Kogyo Co., Ltd .; product name: 125E-0010DG2.5AS, thickness 125 μm) using an applicator to obtain an adhesive resin layer (adhesive layer) after drying After coating so as to have a thickness of 175 μm, the solvent was dried at 90 ° C. for 2 minutes in the drying step to prepare a laminate having an adhesive resin layer laminated thereon.
Next, a separator (manufactured by Fujimori Kogyo Co., Ltd .; product name; 38E-0010BDAS, thickness 38 μm) is pasted onto the top surface of the adhesive resin layer of the obtained laminate, and the adhesive resin film of Example 1 is obtained. Made.

  With respect to Examples 1 to 9 and Comparative Examples 1 to 3, a laminate including a separator film and a substrate was produced under the composition and production conditions of the adhesive raw material composition described in Table 1.

  In Table 1, "SK dyne 2094" and "SK dyne 2147" respectively represent SK dyne (registered trademark) 2094 and SK dyne (registered trademark) 2147. "4HBA" represents 4-hydroxybutyl acrylate. "Perbutyl O" is a thermal polymerization initiator containing t-butylperoxy-2-ethylhexanoate as an active ingredient. “Irg 651” is a photopolymerization initiator containing 2,2-dimethoxy-2-phenylacetophenone (also known as benzyl dimethyl ketal) as an active ingredient. "Perbutyl H" (see Table 3) is a thermal polymerization initiator containing t-butyl hydroperoxide as an active ingredient.

<Test results>

(Method for evaluating appearance after heat press)
As a substrate, one flat polyethylene terephthalate (PET) film was prepared, and another polyethylene terephthalate (PET) film having 20 μm, 50 μm, and 100 μm printing steps formed on the surface was prepared. As the mold, a mold having a smooth surface to each other was used so that the outer surface of the base material after pressing (the outer surface of the laminate) was smooth. The separator on one side is peeled off from the adhesive resin film in advance to bond it to the PET film on which the printing step is formed, and the bonding film and the smooth PET film on which the printing step is not formed are molded by a heat press machine Between the two, heat pressing was performed under the heat pressing conditions shown in “Process conditions after bonding” in Table 1. Immediately after the hot pressing, the appearance of the laminate (bonded product) after bonding was visually confirmed, and evaluation was performed as follows.
:: Air bubbles can not be confirmed between the substrates or in the printing step portion.
Fair: Air bubbles can be observed only slightly between the substrates or at the printing step portion.
X: Air bubbles can be confirmed between the substrates or at the printing step portion.

The ease of bonding was evaluated as follows. The separator on one side of the adhesive resin film is peeled off, and when sticking to the predetermined position of the PET film on which the printing step is formed, there is stiffness and it is easy to be aligned, and the appearance of the laminate after bonding (in particular, biting) The bubbles were visually confirmed. For bonding, a bonding apparatus (product name SE320) manufactured by Crime Products Co., Ltd. was used.
○: Air bubbles remain in the vicinity of the corners of the printing step (because they disappear by heat press).
Δ: Air bubbles remain around the printing step (because they disappear by heat press).
X: Air bubbles of 1 mm or more remain from the printing step (in order not to disappear by heat press).

The thickness retentivity was evaluated as follows with respect to the adhesive resin layer when the coated product wound up with a coating width of 400 mm and tension of 40 N was fed out again.
○: no wrinkles and good appearance
Δ: There are wrinkles but no separator uki can be seen.
X: Wrinkles have entered, the separator has floated, and the thickness of the adhesive resin layer has changed.

For cutting suitability, a pinnacle blade that strikes in a square shape with a blade angle of 30 degrees was installed in the cutting device, and pressing and stripping of unnecessary portions of the periphery were performed. Evaluation was performed as follows.
:: It was easy to remove unnecessary parts around.
○: It was possible to strip around unnecessary parts.
Δ: It was difficult to peel off unnecessary parts around.
X: The cut portion was reattached and could not be easily peeled off.

(Durability test method for bonded products)
In the durability test, the laminate after heat pressing (bonded product) is placed in a high-temperature environment of 85 ° C. dry or a high-temperature high-humidity environment of 85 ° C. 85% RH, taken out after a predetermined time elapses, and visual confirmation It implemented and evaluated as follows.
○: no sticking or peeling of the bonded product.
Fair: There is a small floating or peeling in the bonded product.
X: There is a large floating and peeling in the bonded product.

  The results of the above evaluation test are shown in Table 2 below.

Reference Examples 1 and 2 are examples using an adhesive raw material composition containing a photopolymerization initiator. As a substrate, one flat polyethylene terephthalate (PET) film was prepared, and another polyethylene terephthalate (PET) film having 20 μm, 50 μm, and 100 μm printing steps formed on the surface was prepared. The separator on one side is peeled off from the adhesive resin film to bond it to the PET film on which the printing step is formed, the separator remaining in the two-layer bonded product is peeled off, and the smooth PET film is bonded to PET A three-layer-bonded product of / adhesive resin / PET was produced, and the appearance of the laminate immediately after autoclave treatment was visually confirmed and evaluated as follows.
:: Air bubbles can not be confirmed between the substrates or in the printing step portion.
Fair: Air bubbles can be observed only slightly between the substrates or at the printing step portion.
X: Air bubbles can be confirmed between the substrates or at the printing step portion.

  When the autoclave treatment is carried out, there is a step following property to a substrate having a large step, and if the step deformation amount is about 20 μm, it is possible to adhere well without entering air bubbles. However, the reference example 1 is a reference example in which the step followability is not sufficient for a step having a deformation amount of 50 μ or more, and improvement is necessary. Also, as in Reference Example 2, when the addition amount of the monomer component is increased, the step following property is improved, and it is possible to bond without any bubbles even in the step having a relatively large deformation amount, but for the 100 μm step. Bonding was not sufficient even after bonding and autoclave treatment, thickness retention was poor, and there was a problem that the adhesive component of the bonded part of the laminate exudes from the cut surface when the laminate is cut. It is a reference example. By applying ultraviolet light to the bonded product that can follow the level difference where bubbles can not be confirmed after the above bonding and polymerizing the monomer, it becomes a product where foaming can not be confirmed even in the endurance test, but the bonded product applied to the 100 μm level is an autoclave Since bubbles are generated after the treatment, the bubbles remain as they are even when irradiated with ultraviolet light.

(Result of appearance check and evaluation after heat press)
In the example, no bubble was observed even if the deformation amount was 100 μm, and it was confirmed that the deformation of the substrate due to the press of the mold having the printing step was followed. It is considered that this is because (B) acrylic monomer as a highly fluid component is added to the adhesive raw material composition in addition to (A) acrylic polymer.

  In Comparative Example 3, air bubbles were observed. In this example, the adhesive resin layer is formed of the adhesive raw material composition which does not contain the (B) acrylic monomer, and therefore, it is considered that the adhesive resin layer can not follow the deformation of the substrate by the press of the mold having the printing step.

  In the case of Comparative Examples 1 to 3, the durability in a high temperature environment or a high temperature / high humidity environment was inferior. In Comparative Examples 1 and 2, the adhesive raw material composition which contains the acrylic monomer but does not contain the thermal polymerization initiator is heated by the heat press, so it is considered that the polymerization of the acrylic monomer is difficult to progress. It is considered that Comparative Example 3 had reduced durability because the bonded product had air bubbles.

  In the embodiment, since the adhesive resin layer is bonded to the bonded base material such as PET in a high flowability state, it can be firmly adhered even to fine unevenness. Furthermore, a monomer having high fluidity flows by heat pressing, and after following deformation, the thermal polymerization reaction proceeds gradually by heat, and the monomer component polymerizes, so that the fluidity of the adhesive resin layer decreases. In order to cure in a deformed state, it is considered that not only air bubbles were not generated in the deformed portion, but also foaming between the substrates was not generated.

(Study on manufacturing method of bonded products)
The adhesive raw material composition described in Example 1 was used to study a production method. As shown in Table 3, in the production method described in Example 1, Examples 15 and 16 change the polymerization initiator, and Examples 10, 11, 12, and 14 change the drying conditions of the adhesive resin layer, In Examples 13 and 16, the temperature of the laminate at the time of heat pressing was changed. The boiling point of the solvent of the adhesive resin layer is temperature A, the one-minute half-life temperature of the thermal polymerization initiator is temperature B, the temperature at heating for removing the solvent in the production process of the adhesive resin layer is temperature C, heat curing The press temperature of the mold in the step of

The results of the above evaluation test are shown in Table 4 below. Regarding the productivity, the production process of the adhesive resin layer by application and drying of the adhesive raw material composition was determined as follows.
:: The production speed is sufficiently fast.
○: Production speed is a general condition.
Δ: The production speed is slow.

In Example 11, when the drying time is too long in the drying condition after the application of the adhesive raw material composition, bubbles are slightly contained even if the order of the temperatures A, B, C, and D is the preferred order. The It is considered that this is because the residual resin content is too low and the fluidity of the adhesive resin layer is lost.
In Example 12, since the drying temperature at the time of producing the adhesive resin layer is the same as the boiling point of the solvent, the organic solvent remains in the adhesive resin layer, which takes a long time to dry and also causes evaporation of the solvent at the time of pressing. This is an embodiment in which bubbles due to
In Example 14, since the temperature at the time of drying after application of the adhesive raw material composition is high, the polymerization initiator is deactivated at the time of drying, and the reaction does not proceed sufficiently at the time of pressing, and the acrylic monomer is volatilized. It is thought that air bubbles have been produced very slightly. It is also considered that curing is insufficient.
In Example 15, since the temperature at the time of heat pressing is lower than the one-minute half-life temperature of the thermal polymerization initiator, the thermal polymerization reaction does not occur sufficiently, the acrylic monomer is volatilized, and the curing is also insufficient. It is conceivable.

  The adhesive resin film of each example is heat-pressed under the same conditions as the “appearance evaluation evaluation method after heat press” while the adhesive resin layer is laminated between the separators, and then the cured adhesive resin layer is As a result of analysis by FT-IR (Fourier transform infrared spectroscopy), the peak of carbon-carbon double bond (vinyl group of acrylic monomer etc.) could hardly be confirmed. Furthermore, when analysis was conducted by DSC (differential scanning calorimetry) before and after heat pressing, an exothermic peak was observed in DSC measurement before heat pressing, but no exothermic peak was observed in DSC measurement after heat pressing. From these results, it is considered that the curing reaction is completed under the heat pressing conditions.

In each of the comparative examples, even when hot pressing was performed, FT-IR slightly confirmed a peak which is considered to be the origin of the carbon-carbon double bond.
In the DSC before heat pressing, no exothermic peak was confirmed in Comparative Examples 1 and 2. Since the reaction by heat can not be confirmed, it can be judged that the thermosetting reaction has not progressed. In Comparative Example 3, only the heat generation of the thermal reaction initiator is confirmed, but the polymerization reaction does not proceed because there is no reactive monomer to be polymerized.

  From the above results, by containing the (A) acrylic polymer, the (B) acrylic monomer and the (C) thermal polymerization initiator of which the adhesive resin layer is the main components, high temperature heat press processing is performed. A pressure-sensitive adhesive film can be produced which can suppress bubbles and peeling and form a three-dimensional shape.

DESCRIPTION OF SYMBOLS 10 ... Adhesive resin film, 11 ... Adhesive resin layer, 11a, 11b ... Both surfaces (adhesive surface) of an adhesive resin layer, 12, 13 ... Separator, 12a, 13a ... Surface (peeling surface) of a separator, 20, 30 ... laminates, 21, 22, ... base materials, 21a, 22a ... inner surfaces, 21b, 22b ... outer surfaces, 23 ... convex portions, 24 ... step corners, 25 ... adhesive layers after heat curing, 31, 32 ... molds , 31a, 32a ... pressing surfaces.

Claims (11)

A single-layer adhesive resin layer comprising an acrylic adhesive resin composition having transparency,
The adhesive resin composition comprises (A) 100 parts by weight of an acrylic polymer, (B) 4 to 20 parts by weight of 4-hydroxybutyl acrylate as an acrylic monomer, and (C) a thermal polymerization initiator of 0.001 to 5 parts by weight, and 1.5 equivalents or less of the (D) crosslinking agent relative to the acrylic polymer,
The thermal polymerization initiator is a peroxide,
The crosslinking agent is a crosslinking agent selected from isocyanate crosslinking agents, epoxy crosslinking agents, and metal chelate compounds,
An adhesive resin layer characterized in that the adhesive resin layer has adhesiveness on both sides at normal temperature, and can be thermally cured by heating at a temperature of 100 to 250 ° C. and for a time of 30 seconds to 10 minutes. The storage elastic modulus at a temperature of 23 ° C. after heat curing by heat is higher than that at a temperature of 23 ° C. before heating, and the storage elastic modulus at a temperature of 23 ° C. before heating is 1 × 10 ⁴ to 1 The adhesive resin layer according to claim 1, wherein the adhesive resin layer is × 10 ⁶ Pa and the storage elastic modulus at a temperature of 23 ° C. after thermosetting by heating is 1 × 10 ⁴ to 1 × 10 ⁹ Pa. .   An adhesive resin film, wherein the adhesive resin layer according to claim 1 is laminated between two separators.   A laminated body in which two base materials are laminated via the adhesive resin layer according to claim 1 or 2.   5. The laminate according to claim 4, wherein at least one of the two substrates includes a step of 5 μm to 1 mm in a surface in contact with the adhesive resin layer.   The layered product according to claim 5, wherein said level difference includes a level difference of 50 micrometers-1 mm.   The two sheets of substrates are laminated via the adhesive resin layer according to claim 1, and the adhesive resin layer is laminated while the obtained laminate is sandwiched between two molds. A method for producing a laminate characterized by heat curing. The solvent contained in the raw material composition of the adhesive resin layer is at a temperature A, the temperature at which the thermal polymerization initiator has a half life of one minute is a temperature B, and the solvent is removed in the process for producing the adhesive resin layer Assuming that the temperature at the time of heating is temperature C, and the press temperature of the mold in the step of heat curing the adhesive resin layer is temperature D, each temperature is in the order of the following formula (1) The manufacturing method of the laminated body of Claim 7.
Formula (1) temperature A <temperature C <temperature B <temperature D   The laminate according to claim 7 or 8, wherein at least one of the two substrates includes a step of 5 μm to 1 mm in a surface in contact with the adhesive resin layer. Production method.   The method for manufacturing a laminate according to claim 9, wherein the step includes a step of 50 μm to 1 mm.   The method for producing a laminate according to any one of claims 7 to 10, wherein the temperature of the mold at the time of the heat curing is a temperature of 150 to 300 ° C.

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