JP4937327B2 - Method for producing pressure-sensitive adhesive composition, method for producing pressure-sensitive adhesive film, raw material composition for pressure-sensitive adhesive, and pressure-sensitive adhesive film - Google Patents

Description

The present invention relates to a method for producing a pressure-sensitive adhesive composition, a method for producing a pressure-sensitive adhesive film, a raw material composition for pressure-sensitive adhesive, and a pressure-sensitive adhesive film, and more particularly, under environmental conditions at high temperature and high humidity using an oven. A method for producing a pressure-sensitive adhesive composition, a method for producing a pressure-sensitive adhesive film, a pressure-sensitive adhesive film having excellent performance without causing cloudiness of the pressure-sensitive adhesive layer and lifting and peeling from the adherend even when the durability test is performed and after taking out from the oven. The present invention relates to an agent raw material composition and an adhesive film.
In addition, the pressure-sensitive adhesive composition and pressure-sensitive adhesive film of the present invention can be used when various optical films and protective plates are bonded to the front surface of a display, or when a laminated glass is manufactured by bonding glasses together.

In recent years, in various displays such as a PDP (plasma display), a liquid crystal panel, and an organic EL panel, various optical films and protective plates are attached to the front surface of the display.
For example, in the PDP, in addition to the electromagnetic wave shielding film, a near-infrared absorbing film for preventing malfunction of various remote control switches using the near-infrared wavelength region, and the near-infrared absorbing film used in the near-infrared absorbing film. UV absorbing film to prevent deterioration of infrared absorber over time, neon light cut film for color tone adjustment in the visible light region, antireflection film to prevent external light from being reflected on the surface of the optical filter, etc. , Pasted on the front of the display. By using these films as an optical filter for a display, the image appearance is improved.

Further, in a mobile phone in which a liquid crystal panel is used as a display, a shock absorbing protective plate is attached to the front surface of the liquid crystal panel via an air layer to prevent the liquid crystal panel from cracking. However, recently, in order to reduce weight and thickness, and improve visibility, a thin protective plate is directly bonded using an adhesive layer without providing an air layer on the front surface of a mobile phone liquid crystal panel. Has been done.
Also in PDP, in order to reduce the weight and thickness, and improve the visibility, it has been studied as a direct color filter system that an optical filter film is directly bonded to a PDP panel.

The above optical film and protective plate are bonded to the front of the display using an adhesive layer, but when using the adhesive layer to bond various optical films and protective plates to the display, bubbles are not generated. There was a problem that microbubbles were generated at the interface between the pressure-sensitive adhesive layer and the adherend due to entrainment.
In addition, in a display performance test performed before shipment of the display device, it is necessary to pass an endurance test under environmental conditions at high temperature and high humidity performed using an oven. After removal from the oven, the pressure-sensitive adhesive layer may become cloudy. When a film is pasted on one side, the cloudiness becomes transparent within a few hours. However, when hard materials such as glass or glass / acrylic plates are pasted together, the cloudiness may remain for several days. There was a problem of damaging the product value.

  In this way, there is a problem that micro bubbles are generated in the adhesive layer when an optical film or a protective plate is bonded to the display using adhesive tape, and the environmental conditions of high temperature and high humidity using the oven in the display Various attempts have been made to solve the problem of white turbidity in the pressure-sensitive adhesive layer when the durability test is performed below and after taking out from the oven.

For example, Patent Document 1 discloses a pressure-sensitive adhesive optical film using a pressure-sensitive adhesive layer that improves the repair performance when a depression is generated on the surface of the pressure-sensitive adhesive layer and prevents entrainment of bubbles.
Specifically, two functional groups that react with a polymer and a hydroxyl group containing the alkyl (meth) acrylate having 7 to 18 carbon atoms in the alkyl group and a hydroxyl group-containing monomer in a weight ratio of 100: 0.01 to 5 are included. It is a pressure-sensitive adhesive layer formed from a crosslinked product of the composition containing the compound as described above. After the optical film using the pressure-sensitive adhesive layer is bonded to glass, it is left in an atmosphere of 50 ° C. × 0.05 MPa for 5 minutes, and the presence or absence of microbubbles in the pressure-sensitive adhesive layer is visually confirmed. Although the presence or absence of bubbles is inspected, the generation of microbubbles is prevented.

Patent Document 2 discloses a resin composition containing an acrylic acid derivative, an acrylic acid derivative polymer, and a high molecular weight cross-linking agent for impact absorption necessary for protecting an image display device or the like. . It is said to be useful for preventing cracks in the image display panel or relieving stress and impact and is excellent in transparency.
As a moisture absorption test, the resin sheet was placed in a high-temperature and high-humidity test tank of 60 ° C. and 90% RH for 50 hours, and as a result of confirmation by visual observation, this resin composition was transparent with little foaming. It is said to be excellent.

Patent Document 3 discloses a pressure-sensitive adhesive layer for electronic displays having excellent moisture and heat resistance. Specifically, a pressure-sensitive adhesive composition for electronic display comprising a copolymer and / or a mixture of a (meth) acrylic acid alkyl ester monomer and a carboxyl group-containing monomer, further comprising a monomer having an alkyleneoxy group, And the adhesive composition for electronic displays characterized by including a hydroxyl group containing (meth) acrylic acid ester monomer.
As a moisture absorption test, a laminate bonded to a glass plate through an adhesive layer laminated to a resin film was left in an environment of 60 ° C. and 90% RH for 120 hours, and then left at room temperature (25 ° C.) for 30 minutes. Thereafter, the haze value is measured to determine the transparency of the laminate. According to this pressure-sensitive adhesive composition, even after being left under high temperature and high humidity, it is said that high transparency can be maintained with less foaming.

JP 2003-262729 A JP 2008-248221 A JP 2008-001739 A

The pressure-sensitive adhesive composition and pressure-sensitive adhesive layer described in Patent Documents 1 to 3 described above are performed under an environment of 60 ° C. and 90% RH as high-temperature and high-humidity environmental conditions.
By the way, with respect to Patent Document 3, the pressure-sensitive adhesive layer for the test is tested in an oven under an environment of 60 ° C. and 90% RH, and after taking it out, it is left to stand at room temperature (25 ° C.) for 30 minutes. The test method is adopted. That is, according to the test method of Patent Document 3, the cloudiness of the pressure-sensitive adhesive layer may be determined to pass even if the cloudiness starts within a few minutes immediately after taking out from the oven and becomes inconspicuous after 30 minutes. In fact, with respect to Patent Document 2, unlike Example 19 in which white turbidity was maintained even after the moisture absorption test, Example 18 in which slight turbidity was observed immediately after production was also evaluated as A (no white turbidity was observed in the moisture absorption test). Therefore, turbidity immediately after production is not considered.
In this case, when a thin resin film such as polyethylene terephthalate (PET) is pasted on one side or both sides, it is a phenomenon that is not very noticeable, but when a material with high gas barrier properties such as an acrylic plate and glass or glass is pasted, Using this pressure-sensitive adhesive layer, a phenomenon occurs in which white turbidity starts in a few minutes immediately after taking out from an oven in an environment of 60 ° C. and 90% RH, and the white turbidity remains for several hours or more. It becomes a big problem depending on the environment.
In recent years, with the expansion of display applications, durability performance under severer environmental conditions is required as compared with conventional environmental test conditions. For example, in an adhesive tape that bonds an optical film used in an on-vehicle display, the adhesive layer does not cause white turbidity and does not float or peel off from the adherend even under environmental conditions of 85 ° C. and 95% RH. There is a need for a composition and an adhesive tape using the composition.

However, the pressure-sensitive adhesive composition described in Patent Document 1 provides an alkyl (meth) acrylate (A) having 7 to 18 carbon atoms in the alkyl group serving as the skeleton of the acrylic polymer and a hydroxyl group to the acrylic polymer. After forming a copolymer with the hydroxyl group-containing monomer (B), a composition (crosslinking agent) containing a compound having two or more functional groups that react with a hydroxyl group is added to perform a crosslinking reaction. The weight ratio of (B) to (A) is 100: 0.01-5, and the addition amount of (B) is small, contributing to moisture retention and high temperature. There is too little absolute amount of the hydroxyl group considered to be effective for preventing foaming in the environmental test under humidity. Furthermore, the hydroxyl group imparted to the copolymer is consumed in the crosslinking reaction, and the number of hydroxyl groups remaining after the crosslinking reaction is limited.
Therefore, under severe environmental conditions of high temperature and high humidity, when used as a pressure-sensitive adhesive tape with a thick adhesive layer, the adhesive layer may become clouded due to moisture or exposed to high temperatures. There has been a problem that the floating and peeling from the adherend due to deformation cannot be prevented.

  In addition, the pressure-sensitive adhesive composition described in Patent Document 2 is a copolymer obtained by polymerizing a mixture of an alkyl acrylate (A) having an alkyl group having 4 to 18 carbon atoms and a hydroxyl group-containing acrylate (B), It is a pressure-sensitive adhesive composition obtained by adding a monomer mixture of (A) and (B) and a high molecular weight cross-linking agent, followed by a cross-linking reaction. In the case of Patent Document 2, it is not explicitly stated that it is a pressure-sensitive adhesive composition that does not cause cloudiness of the pressure-sensitive adhesive layer even under environmental conditions of 85 ° C. and 95% RH, and a pressure-sensitive adhesive tape using the same. Since the acrylic acid alkyl ester monomer is introduced excessively, it is necessary to devise facilities such as pouring the resin into the mold as in the embodiment, and weakening the ultraviolet rays with glass and irradiating for a long time. Moreover, although it is stated that it is a pressure-sensitive adhesive composition that does not cause cloudiness of the pressure-sensitive adhesive layer even under environmental conditions of 60 ° C. and 90% RH, and a pressure-sensitive adhesive tape using the same, it is necessary to irradiate weak ultraviolet rays for a long time. Productivity is poor.

In the pressure-sensitive adhesive composition described in Patent Document 3, a copolymer of a (meth) acrylic acid alkyl ester monomer and a carboxyl group-containing monomer is used.
Also, in the case of Patent Document 3, as in Patent Document 2, it is clearly stated that the pressure-sensitive adhesive composition does not cause white turbidity of the pressure-sensitive adhesive layer even under environmental conditions of 85 ° C. and 95% RH, and a pressure-sensitive adhesive tape using the same. However, since the (meth) acrylic acid alkyl ester monomer is introduced excessively, it is necessary to irradiate the ultraviolet rays as weak as possible at the time of ultraviolet curing as in the examples for a long time. Moreover, although it is stated that it is a pressure-sensitive adhesive composition that does not cause cloudiness of the pressure-sensitive adhesive layer even under environmental conditions of 60 ° C. and 90% RH, and a pressure-sensitive adhesive tape using the same, it is necessary to irradiate weak ultraviolet rays for a long time. Productivity is poor.

  As described above, in the prior art, the pressure-sensitive adhesive layer may be clouded even under extremely severe high-temperature and high-humidity environmental conditions such as 85 ° C. and 95% RH, which are applied to an on-vehicle display. It was not a technique that does not float and peel off the adherend and is provided at low cost with good productivity.

  That is, the object of the present invention is to perform an endurance test under an environmental condition at a high temperature and high humidity such as (60 ° C., 90% RH) or (85 ° C., 95% RH) using an oven and from the oven. It is to provide a method for producing a pressure-sensitive adhesive composition and a pressure-sensitive adhesive composition that do not cause cloudiness of the pressure-sensitive adhesive layer or lift and peel off from the adherend even after removal, and a pressure-sensitive adhesive film using the same.

In order to prevent clouding of the pressure-sensitive adhesive layer without agglomerating water molecules due to a sudden change in the external environment, in the present invention, in the production of an acrylic polymer having a hydroxyl group, a monomer having no hydroxyl group is used as much as possible. The technical idea is to obtain a pressure-sensitive adhesive composition in which water molecules are dispersed in an invisible state by polymerizing as a single substance.
Furthermore, in order to prevent lifting and peeling from the adherend, the pressure-sensitive adhesive is crosslinked to impart heat resistance, and the crosslinked pressure-sensitive adhesive is not covered even if the adherend is deformed by exposure to a high temperature environment. To be able to follow the deformation of the kimono.

In the present invention, a polymer having a hydroxyl group obtained by polymerizing at least one monomer of a hydroxyl group-containing (meth) acrylate is introduced into the pressure-sensitive adhesive layer to participate in preventing aggregation of water molecules.
Therefore, in the present invention, in order to solve the above problems, an acrylic polymer as a main agent is polymerized in advance, and this is a syrup in which at least one monomer of a hydroxyl group-containing (meth) acrylate is dissolved, Alternatively, a pressure-sensitive adhesive is obtained by adding a bifunctional crosslinking agent in an amount of 0.1 equivalent or less with respect to the crosslinking point of the polymer and a photopolymerization initiator to a solvent-based acrylic resin obtained by dissolving in an organic solvent liquid. Hydroxyl groups involved in preventing water molecule aggregation by preparing a coating solution (raw material composition for pressure-sensitive adhesive that becomes a precursor of the pressure-sensitive adhesive layer), and applying, drying, irradiating with light, and curing this coating solution. And a pressure-sensitive adhesive composition crosslinked to such an extent that it can follow the deformation of the adherend. Thereby, the acrylic polymer which has a hydroxyl group can be produced efficiently, and the polymer which is hard to mix uniformly can be mixed without a problem, and the adhesive composition excellent in the optical characteristic is obtained. Furthermore, since the addition amount of the monomer with respect to the acrylic polymer used as the main ingredient that has been polymerized in advance can be reduced as compared with the prior art, a highly productive pressure-sensitive adhesive film can be provided.

In order to solve the above problems, the present invention is a method for producing a pressure-sensitive adhesive composition comprising an acrylic polymer containing a hydroxyl group as a functional group,
At least the following steps (1) to (3)
(1) A polymer production process for obtaining a main polymer using a mixed solvent liquid containing at least one kind of acrylic monomer, wherein at least one kind of acrylic monomer having an ester group is 85 to 95 parts by weight, A step of obtaining a main polymer polymerized from a monomer in which at least one of acrylic monomers having a carboxyl group contains 5 to 15 parts by weight;
(2) The main polymer is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer with at least one kind of hydroxyl group-containing (meth) acrylate monomer, photopolymerization initiator, and polymer. Adding an amount of a bifunctional cross-linking agent, and preparing a pressure-sensitive adhesive raw material composition containing these as essential components,
(3) A step of obtaining a pressure-sensitive adhesive composition by performing a polymerization reaction by light irradiation and a crosslinking reaction by curing using the raw material composition for pressure-sensitive adhesives,
Are produced through the order of (1) to (3), and a method for producing a pressure-sensitive adhesive composition is provided.

Moreover, the present invention is a method for producing an adhesive film comprising an adhesive layer containing an acrylic polymer containing a hydroxyl group as a functional group,
At least the following steps (1) to (4)
(1) A polymer production process for obtaining a main polymer using a mixed solvent liquid containing at least one kind of acrylic monomer, wherein at least one kind of acrylic monomer having an ester group is 85 to 95 parts by weight, A step of obtaining a main polymer polymerized from a monomer in which at least one of acrylic monomers having a carboxyl group contains 5 to 15 parts by weight;
(2) The main polymer is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer with at least one kind of hydroxyl group-containing (meth) acrylate monomer, photopolymerization initiator, and polymer. Adding an amount of a bifunctional cross-linking agent, and preparing a pressure-sensitive adhesive raw material composition containing these as essential components,
(3) A process of forming the pressure-sensitive adhesive coating film by applying and drying the pressure-sensitive adhesive raw material composition on the base material or separator of the pressure-sensitive adhesive film,
(4) A step of obtaining a pressure-sensitive adhesive layer by subjecting the pressure-sensitive adhesive coating film to a polymerization reaction by light irradiation and a crosslinking reaction by curing;
Are produced through the order of (1) to (4), and a method for producing an adhesive film is provided.

The present invention also provides:
(A) A main polymer polymerized from a monomer containing at least one acrylic monomer having an ester group in an amount of 85 to 95 parts by weight and at least one acrylic monomer having a carboxyl group in an amount of 5 to 15 parts by weight. : 100 parts by weight;
(B) at least one kind of hydroxyl group-containing (meth) acrylate monomer: 5 to 20 parts by weight;
(C) Photopolymerization initiator: 0.01 to 0.5 parts by weight;
(D) 1.0 to 3.0 parts by weight of the bifunctional crosslinking agent, which is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer;
As an essential component , and the molecular weight distribution of the main polymer is 70,000 or more in number average molecular weight (Mn) and 1 million or more in weight average molecular weight (Mw) I will provide a.

The present invention also provides:
(A) A main polymer polymerized from a monomer containing at least one acrylic monomer having an ester group in an amount of 85 to 95 parts by weight and at least one acrylic monomer having a carboxyl group in an amount of 5 to 15 parts by weight. : 100 parts by weight;
(B) at least one kind of hydroxyl group-containing (meth) acrylate monomer: 5 to 20 parts by weight;
(C) Photopolymerization initiator: 0.01 to 0.5 parts by weight;
(D) 1.0 to 3.0 parts by weight of the bifunctional crosslinking agent, which is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer;
As an essential component , and the molecular weight distribution of the main polymer is 70,000 or more in number average molecular weight (Mn) and 1 million or more in weight average molecular weight (Mw) An adhesive film having a pressure-sensitive adhesive layer having a thickness of 0.05 to 3 mm obtained by applying a polymerization reaction by light irradiation and a crosslinking reaction by curing after coating on a substrate or a separator is provided.

The present invention relates to the glass and acrylic resin when the pressure-sensitive adhesive layer is peeled off at a peeling speed of 300 mm / min after being left to stand in an environment of 23 ° C. and 50% RH for 1 hour after being stuck to an adherend. The adhesive strength is preferably 10 N / 25 mm or more. In order to obtain such a high adhesive strength, the storage elastic modulus (G ′) at 23 ° C. and 1 Hz of the adhesive constituting the adhesive layer is 1 × 10 ⁴ Pa or more and less than 1 × 10 ⁶ Pa. It is preferable.
The present invention is suitable for, for example, an adhesive tape used for attaching a member to a display.

According to the present invention described above, by suppressing the crosslinking reaction of the acrylic polymer to a minimum, the number of hydroxyl groups introduced into the polymer can be prevented from being consumed and reduced, and a hydroxyl group capable of adsorbing water molecules is possible. By providing a pressure-sensitive adhesive composition that is present in the required quantity in a dispersed state as much as possible, moisture under high-temperature and high-humidity environmental conditions can be adsorbed to the hydroxyl group-containing polymer, and the pressure-sensitive adhesive layer is formed to increase buffering properties. Even if the thickness is increased, it is possible to prevent the occurrence of white turbidity due to aggregation of absorbed water molecules.
Moreover, it is possible to thicken the coating thickness to a base material by adjusting the fluidity | liquidity of an adhesive coating liquid appropriately, and can form a thick adhesive tape and can improve buffering property.
Furthermore, the amount and type of the crosslinking agent is a bifunctional crosslinking agent in an amount of 0.1 equivalent or less with respect to the crosslinking point of the polymer, so that the adherend is exposed to a high temperature environment. The pressure-sensitive adhesive is cross-linked to such an extent that it can follow the deformation to impart heat resistance, and it is possible to prevent lifting and peeling from the adherend.

According to the first aspect of the present invention, even if the thickness of the pressure-sensitive adhesive layer is increased in order to increase the buffering property, it is caused by the aggregation of water molecules after being removed from the environmental conditions at high temperature and high humidity. It is possible to provide a method for producing a pressure-sensitive adhesive composition in which the pressure-sensitive adhesive layer does not become cloudy or does not float or peel off the adherend.
According to the invention of claim 2, even if the thickness of the pressure-sensitive adhesive layer is increased in order to increase the buffering property, it is caused by the aggregation of water molecules after environmental conditions at high temperature and high humidity and after the removal. It is possible to provide a method for producing a pressure-sensitive adhesive film in which the pressure-sensitive adhesive layer does not become cloudy or does not float or peel off from the adherend.

According to the invention of claim 3, even if the pressure-sensitive adhesive layer is thickened to increase the buffering property, the pressure-sensitive adhesive is caused by the aggregation of water molecules after being removed from the environmental conditions at high temperature and high humidity. It is possible to provide a pressure-sensitive adhesive coating solution (raw material composition for pressure-sensitive adhesive) that does not cause layer turbidity or floating and peeling from the adherend.
According to the inventions according to claims 4 to 6, even if the pressure-sensitive adhesive layer is thickened to increase the buffering property, it is caused by aggregation of water molecules after environmental conditions at high temperature and high humidity and after removal from the environmental conditions. It is possible to provide a pressure-sensitive adhesive film in which the pressure-sensitive adhesive layer does not become cloudy or does not float or peel off from the adherend.

(A) is sectional drawing which shows typically an example of the single-sided adhesive tape which has an adhesive layer formed using the adhesive composition of this invention, (b) uses the adhesive composition of this invention. It is sectional drawing which shows typically an example of the transfer tape which has the adhesive layer formed in this way. It is explanatory drawing which shows typically an example of the manufacturing method of the adhesive film of this invention. (A) About Example 6 and Comparative Example 2, it is a graph which shows the change of the haze value from immediately after taking out from a high-temperature, high-humidity test oven, (b) is the range for which time (a) is 0 to 40 minutes. It is the graph expanded by.

Hereinafter, preferred embodiments of the present invention will be described.
The pressure sensitive adhesive raw material composition of the present invention crosslinks at least one hydroxyl group-containing monomer (monomer B) with a polymerization initiator for polymerizing the monomer B, the main polymer (polymer A), and the main polymer. It was mixed with a crosslinking agent. This raw material composition for pressure-sensitive adhesives contains at least one hydroxyl group-containing (meth) acrylate as a photopolymerizable compound that is polymerized by energy rays. The monomer of (meth) acrylate is a polymerizable compound having a (meth) acryl group which is a vinyl group capable of radical polymerization with a photopolymerization initiator, and is curable, for example, in the range of 300 nm to 400 nm. Is an ultraviolet curable resin material.
In this specification, (meth) acrylate is a general term for acrylate and methacrylate.

The polymer A is not particularly limited as long as it is the main component of the pressure-sensitive adhesive and the acrylic monomer (monomer B) containing a hydroxyl group is easily dispersed.
In order to easily disperse the monomer B, an acrylic polymer is preferable, and a hydrophilic monomer is preferably copolymerized. This is because the monomer B is acrylic and contains a hydroxyl group. In addition, since the raw material composition for pressure-sensitive adhesives of the present invention is used for optical applications, it is necessary to have transparency, and it is easy to control the strength of adhesive force. An acrylic polymer is preferred.

When the raw material composition for pressure-sensitive adhesives of the present invention is applied to a substrate (or a separator) and dried and then polymerized by light irradiation, a pressure-sensitive adhesive film is obtained. Moreover, the raw material composition for pressure-sensitive adhesives of the present invention contains a cross-linking agent for cross-linking the polymer, and the content of the cross-linking agent is less than 1 equivalent to the cross-linking point of the polymer (preferably, for example, 0.5 Equivalent or less). As a result, even if the crosslinking agent can be crosslinked with the hydroxyl group of the polymer B like an isocyanate compound, at least a part of the hydroxyl group of the polymer B is not crosslinked, and the uncrosslinked hydroxyl group is dispersed. Therefore, a pressure-sensitive adhesive layer excellent in moisture adsorption ability can be obtained.
Furthermore, in the present invention, the amount and type of the crosslinking agent is a bifunctional crosslinking agent in an amount of 0.1 equivalent or less with respect to the crosslinking point of the polymer, so that the deformation of the adherend can be followed. The pressure-sensitive adhesive is crosslinked to impart heat resistance, and can be prevented from floating and peeling off from the adherend.

  In the present specification, the adhesive film is not particularly required to be distinguished by width, and includes both the adhesive tape and the adhesive sheet specified in JIS Z 0109. Specific examples thereof include a single-sided adhesive tape (or single-sided adhesive sheet) having an adhesive layer on one side of the substrate, a double-sided adhesive tape (or double-sided adhesive sheet) having an adhesive layer on both sides of the substrate, and a substrate. Transfer tape (transfer tape) in which the pressure-sensitive adhesive layer is formed in a film form without having a film. The pressure-sensitive adhesive sheet can have a large area, and may be used with its wide width, or may be cut into a tape shape and used as a pressure-sensitive adhesive tape. In particular, a pressure-sensitive adhesive sheet or pressure-sensitive adhesive tape wound in a roll shape is suitable for an application in which a member is bonded to a display.

FIG. 1A schematically shows an example of a single-sided pressure-sensitive adhesive tape 5 having a pressure-sensitive adhesive layer 2 formed using the pressure-sensitive adhesive composition of the present invention. In this single-sided adhesive tape 5, an adhesive layer 2 is formed on one side of a base material 1 that serves as a support for the adhesive layer 2, and the adhesive surface of the adhesive layer 2 is protected by a separator 3. At the time of use, the separator 3 is peeled to expose the adhesive surface, and the base material 1 is laminated on the back surface of the pressure-sensitive adhesive layer 2 and is bonded to the adherend.
The structure of the double-sided pressure-sensitive adhesive tape having a base material is not particularly shown, but a pressure-sensitive adhesive layer is formed on both surfaces of the base material, and the pressure-sensitive adhesive surface of each pressure-sensitive adhesive layer has a structure protected by a separator.

FIG. 1B schematically shows an example of the transfer tape 6 having the pressure-sensitive adhesive layer 2 formed using the pressure-sensitive adhesive composition of the present invention. In this transfer tape 6, separators 3 and 3 are provided on both sides of the pressure-sensitive adhesive layer 2. At the time of use, one separator 3 is peeled off, and one adhesive surface is exposed and bonded to the adherend. Furthermore, only the film-like pressure-sensitive adhesive layer 2 can be transferred (transferred) to the adherend by peeling off the other separator 3. After the other separator 3 is peeled off, another adherend can be bonded to the new adhesive surface.
About the improvement effect that can prevent the occurrence of white turbidity under environmental conditions at high temperature and high humidity in the present invention, the permeability of moisture such as glass (inorganic glass) or acrylic resin (acrylic glass) to be bonded in the form of transfer tape In particular, a remarkable effect can be obtained in the case of a bad one. This is due to the following reason.
When pasting a resin film with good water molecule permeability, the water molecules dispersed in the adhesive tape layer can be easily penetrated and passed through in the case of a resin film. If the water molecules are reduced, even if water molecules are aggregated, the water molecules are immediately removed through the resin film. However, when pasting a material with poor water molecule permeability, if water molecules aggregate and become cloudy, the water molecules diffuse after spreading to the peripheral edge of the adhesive tape, and thus the cloudiness continues for a long time. Because it will be.

In the present invention, at least one kind of acrylic monomer having an ester group (—COO—) and at least one kind of acrylic monomer having a carboxyl group (—COOH) are contained as monomers that are raw materials for the polymer A. In addition, various other compounds can be used. Examples of the acrylic monomer having an ester group (—COO—) include, for example, a general formula CH ₂ ═CR ¹ —COOR ² (wherein R ¹ is hydrogen or a methyl group, and R ² is an alkyl group having 1 to 14 carbon atoms). And (meth) acrylates such as hydroxyl group-containing (meth) acrylates.

Specific examples of the alkyl (meth) acrylate represented by the general formula CH ₂ = CR 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). Are methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, 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, isononyl (meth) acrylate , Decyl (meth) acrylate, Sil (meth) acrylate and the like, it may be used singly or in combination of two or more. Of these, 2-ethylhexyl (meth) acrylate and n-butyl (meth) acrylate are preferably used.
In the alkyl (meth) acrylate, the alkyl group R ² has 1 to 14 carbon atoms from the viewpoint of adhesive strength. It is not preferable that the alkyl group has 15 or more carbon atoms because the adhesive strength may be reduced. The alkyl group R ² preferably has 1 to 12 carbon atoms, preferably 4 to 12 carbon atoms, and more preferably 4 to 8 carbon atoms.
Moreover, among alkyl (meth) acrylates having 1 to 14 carbon atoms in the alkyl group R ² , alkyl (meth) acrylates having 1 to 3 or 13 to 14 carbon atoms in the alkyl group R ² are used as a part of the monomer. However, it is preferable to use an alkyl (meth) acrylate having 4 to 12 carbon atoms of the alkyl group R ² as an essential component (for example, 50 to 100 mol%).
Incidentally, these alkyl groups R ² may be a straight chain or may be branched.

Examples of the (meth) acrylate containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and polyethylene glycol mono (meth) acrylate. , Polypropylene glycol mono (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, and the like.
Examples of the acrylic monomer containing a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and 2-acryloylethyl succinic acid.

  The mixing ratio of the acrylic monomer having an ester group and the acrylic monomer having a carboxyl group is such that the pressure-sensitive adhesive is crosslinked to the extent that it can follow the deformation of the adherend to impart heat resistance, and the floating from the adherend and In order to prevent peeling, the mixing ratio of at least one kind of acrylic monomer having an ester group is 85 to 95 parts by weight, and at least one kind of acrylic monomer having a carboxyl group is a mixing ratio of 5 to 15 parts by weight. preferable.

Another monomer can be added to the raw material monomer of the polymer A. For example, a monomer having a hydrophilic group such as a carboxyl group, an alkoxysilyl group, an amino group, a hydroxyl group, or a sulfonic acid group can be selected and used.
Among the monomers constituting the polymer A, the blending ratio of the alkyl (meth) acrylate and the monomer having a hydrophilic group depends on the characteristics required for the pressure-sensitive adhesive, the type of monomer, the weight ratio of the hydrophilic group in one molecule, and the like. Although different, for example, 5 to 50% by weight is a monomer having a hydrophilic group, and 95 to 50% by weight is preferably an alkyl (meth) acrylate.

Examples of the acrylic monomer containing an alkoxysilyl group include γ-trimethoxysilylpropyl (meth) acrylate, γ-methyldimethoxysilylpropyl (meth) acrylate, and γ-triethoxysilylpropyl (meth) acrylate. Can be mentioned.
Examples of the non-acrylic monomer containing an alkoxysilyl group include vinylmethoxysilane and vinyltrimethoxysilane.
Examples of the acrylic monomer containing an amino group include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and monomethylaminoethyl (meth) acrylate. In addition to (meth) acrylates containing amino groups, (meth) acrylic acid amide, itaconic acid amide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, N-methoxymethylacrylamide, N-ethoxymethyl ( Examples include meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide.

The polymer A is preferably composed of an acrylic monomer (an alkyl (meth) acrylate and an acrylic monomer having a hydrophilic group) for the most part (for example, 50% by weight or more, more preferably 80% by weight or more) Monomers other than acrylic monomers (non-acrylic monomers) can be used in combination so as not to impair the effects of the present invention.
Polymerization of the acrylic monomer constituting the polymer A and the optionally blended non-acrylic monomer can be carried out by a known method such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. The easy solution polymerization is preferably used. Specific examples of the organic solvent used in the solution polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic esters such as ethyl acetate and butyl acetate, and alicyclic hydrocarbons such as cyclohexane. , Aliphatic hydrocarbons such as hexane, pentane and the like, but not particularly limited as long as the polymerization reaction is not inhibited. These solvents may be used alone or in combination of two or more. What is necessary is just to determine the usage-amount of a solvent suitably.
In general, in the solution polymerization reaction, the molecular weight of the polymer produced decreases as the polymerization temperature increases. In carrying out the polymerization reaction at the reflux temperature of the solvent, a polymer can be obtained while removing the heat of polymerization reaction by using a solvent having a boiling point temperature suitable for the polymerization reaction.

The molecular weight distribution of the polymer A is preferably 70,000 or more in terms of number average molecular weight (Mn) and 1,000,000 or more in terms of weight average molecular weight (Mw). Furthermore, the weight average molecular weight (Mw) is more preferably 12 million or more. Thus, when the molecular weight of the polymer A is large, the heat resistance and the weather resistance are more excellent.
If the molecular weight is too large, the viscosity is too high and the processability is deteriorated. It is considered that this upper limit can be further widened by devising the coating method such as raising the temperature of the paint. However, when coating is performed at room temperature, for example, a material having an Mw of less than 5 million is considered preferable.

Moreover, the raw material composition for pressure-sensitive adhesives of the present invention contains at least one monomer (monomer B) of a hydroxyl group-containing (meth) acrylate.
In one preferable embodiment of the raw material composition for pressure-sensitive adhesives of the present invention, an acrylic polymer obtained by polymerizing a monomer of alkyl (meth) acrylate and acrylic acid not containing a hydroxyl group, and a hydroxyl group-containing ( The monomer of (meth) acrylate exists in the state of being mixed separately without being copolymerized. In another preferred embodiment, the polymer A obtained by polymerizing a monomer containing a hydrophilic monomer and a hydroxyl group-containing (meth) acrylate monomer are contained in the pressure-sensitive adhesive raw material composition. .

The content of monomer B (the total amount when monomer B is two or more) is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the main polymer (polymer A), and is 85 ° C. 95 When high durability is required, such as when a test is performed in a% RH environment, the amount is more preferably 5 to 15 parts by weight.
The pressure-sensitive adhesive composition comprising a known hydroxyl group-containing acrylic polymer may contain some (meth) acrylate monomers containing hydroxyl groups as unreacted monomers. Compared to the content of hydroxyl group-containing (meth) acrylate in the raw material composition for pressure-sensitive adhesives of the invention, the content is only extremely low.

  The raw material composition for pressure-sensitive adhesives of the present invention is an acrylic syrup containing a main polymer, a hydroxyl group-containing (meth) acrylate monomer, a photopolymerization initiator, and a crosslinking agent, or coated and hydroxyl group-containing. In order to uniformly disperse the monomer, the acrylic syrup is prepared as a resin solution dissolved in an organic solvent.

In the step of dissolving the hydroxyl group-containing monomer in the main polymer to obtain an acrylic syrup, before dissolving the hydroxyl group-containing monomer in the main polymer, the organic solvent used in the polymerization reaction is removed, and the obtained liquid syrup is obtained. The main polymer is preferably separated and washed with water or an organic solvent as necessary. Thereby, the polymerization reaction of the main polymer can be completely stopped, and unreacted acrylic monomers can be removed from the main polymer. In addition, the weight of the main polymer can be quantified more accurately, and an acrylic syrup in which the contents of the hydroxyl group-containing monomer, the crosslinking agent and the photopolymerization initiator used in the next step are more appropriately adjusted can be produced. When preparing an acrylic syrup, the removal of the organic solvent used in the polymerization reaction may be performed after the hydroxyl group-containing monomer is dissolved in the main polymer.
In addition, after adding a photopolymerization initiator to an acrylic syrup, the polymerization reaction may proceed when ultraviolet light contained in room light or sunlight acts on the acrylic syrup, making it difficult to manage. Is preferably added immediately before the coating step, which is a subsequent step. This is the same for resin solutions in which acrylic syrup is dissolved in an organic solvent. Care should be taken to prevent the photoinitiator from starting the reaction before coating and film formation due to some external factor. It is.

  The raw material composition for pressure-sensitive adhesives of the present invention is preferably a pressure-sensitive adhesive coating solution containing an appropriate amount of an organic solvent in order to impart fluidity suitable for application to a substrate. Specific examples of the organic solvent used in the adhesive coating solution include aromatic hydrocarbons such as toluene and xylene, aliphatic esters such as ethyl acetate and butyl acetate, and alicyclic carbonization such as cyclohexane. Examples thereof include aliphatic hydrocarbons such as hydrogen, hexane, and pentane, but are not particularly limited as long as the purpose of coating and dispersion can be achieved.

  When preparing the pressure-sensitive adhesive coating solution, it is sufficient to obtain an organic solvent solution in which the main polymer, the hydroxyl group-containing monomer, the photopolymerization initiator, and the crosslinking agent are dissolved in an organic solvent at an appropriate blending ratio. The order of making them is not particularly limited. For example, a hydroxyl group-containing monomer, a photopolymerization initiator, and a crosslinking agent are directly added to an acrylic syrup obtained by polymerizing a main polymer, or a hydroxyl group-containing monomer, a photopolymerization initiator, and a crosslinking agent are added to an appropriate amount of an organic solvent. A dissolved liquid may be added.

The hydroxyl group-containing (meth) acrylate monomers used as the monomer B in the present invention are 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylate, 3-hydroxylpropyl (meth) acrylate, 4- Hydroxylbutyl (meth) acrylate, 5-hydroxylpentyl (meth) acrylate, 6-hydroxylhexyl (meth) acrylate, 7-hydroxylheptyl (meth) acrylate, 8-hydroxyloctyl (meth) acrylate, 7-methyl-8-hydroxyl Octyl (meth) acrylate, 2-methyl-8-hydroxyloctyl (meth) acrylate, 9-hydroxyl nonyl (meth) acrylate, 10-hydroxyldecyl (meth) acrylate, 12- B hexyl lauryl (meth) acrylate and the like, they may be used in combination of two or more may be used alone. In particular, 2-hydroxylethyl (meth) acrylate, hydroxylpropyl (meth) acrylate, and 4-hydroxylbutyl (meth) acrylate are preferably used.
The hydroxyl group-containing (meth) acrylate is obtained by esterifying one hydroxyl group of two hydroxyl groups of a dihydric alcohol (diol compound) with acrylic acid or methacrylic acid. A hydroxyalkyl (meth) acrylate having one vinyl group at a time is preferably used.

  The type of monomer used in the present invention (the monomer constituting the polymer A and the monomer B) varies depending on the required adhesive strength and storage elastic modulus of the adhesive tape. Since a hard adhesive composition having a high elastic modulus may be used, as an approximate guide for the monomer, those having a Tg of room temperature or higher are preferable. When a strong adhesive force is required or when it is desired to lower the storage elastic modulus, a monomer having a Tg lower than room temperature and preferably a Tg minus temperature is required.

Although it does not specifically limit as a photoinitiator (polymerization catalyst), For example, an acetophenone type photoinitiator, a benzoin type photoinitiator, a benzophenone type photoinitiator, a thioxanthone type photoinitiator, a thioxanthone type photopolymerization An initiator etc. are mentioned.
As the acetophenone photopolymerization initiator, acetophenone, p- (tert-butyl) 1 ′, 1 ′, 1′-trichloroacetophenone, chloroacetophenone, 2 ′, 2′-diethoxyacetophenone, hydroxylacetophenone, 2,2- Examples include dimethoxy-2′-phenylacetophenone, 2-aminoacetophenone, dialkylaminoacetophenone and the like.
Benzoin photopolymerization initiators include benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxyl cyclohexyl phenyl ketone, 2-hydroxyl 2-methyl-1-phenyl-2-methyl Propan-1-one, 1- (4-isopropylphenyl) -2-hydroxyl 2-methylpropan-1-one, benzyldimethyl ketal and the like can be mentioned.
Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, methyl-o-benzoylbenzoate, 4-phenylbenzophenone, hydroxylbenzophenone, hydroxylpropylbenzophenone, acrylic benzophenone, 4,4′-bis (dimethyl). Amino) benzophenone and the like.
Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, diethylthioxanthone, and dimethylthioxanthone.
Other photopolymerization initiators include α-acyl oxime ester, benzyl- (o-ethoxycarbonyl) -α-monooxime, acyl phosphine oxide, glyoxy ester, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, tetra Examples include methyl thiuram sulfide, azobisisobutyronitrile, benzoyl peroxide, dialkyl peroxide, tert-butyl peroxypivalate and the like.

These photopolymerization initiators may be used alone or in combination of two or more. Content of a photoinitiator is 0.02-10 mass% in the weight percentage which makes 100 mass% the whole quantity of polymeric compound (In the case of this invention, (meth) acrylate containing a hydroxyl group). Is preferable, and it is especially preferable that it is 0.1-5 mass%. If the content of the photopolymerization initiator is 0.02% by mass or more, the polymerizable compound can be polymerized in a short time, and if it is 10% by mass or less, the residue of the photopolymerization initiator hardly remains in the cured product. .
In addition, as described above, the hydroxyl group-containing (meth) acrylate monomer (total amount when two or more types are used) is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the main polymer. When high durability is required such as in a test under a 95% RH environment, the content of the photopolymerization initiator based on 100 parts by weight of the main polymer is more preferably 5 to 15 parts by weight. 0.01 to 0.5 part by weight is preferable.

  In the present invention, in the pressure-sensitive adhesive composition after photopolymerization, it is desirable to polymerize the monomer in the range of 40 to 80% by weight, preferably 50 to 75% by weight. That is, it is desirable to leave unreacted monomer in the range of 60 to 20% by weight, preferably 50 to 25% by weight. When the polymerization rate is less than 40% by weight, sufficient tackiness is not imparted to the obtained polymer, and when the polymerization rate exceeds 80% by weight, the cohesive force is reduced, and the pressure-sensitive adhesive When the layer is peeled and removed, an adhesive residue phenomenon may occur.

The bifunctional crosslinking agent is not particularly limited as long as it is a compound having two functional groups that undergo crosslinking reaction in one molecule. Examples of such a bifunctional crosslinking agent include a bifunctional epoxy compound and a bifunctional isocyanate.
Examples of bifunctional epoxy compounds include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether. Aliphatic bifunctional epoxy compounds such as 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, o-phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, resorcin diglycidyl ether, etc. Aromatic bifunctional epoxy compounds can be mentioned. The epoxy group of the bifunctional epoxy compound can crosslink with the carboxyl group of the polymer.
Examples of the bifunctional isocyanate include aliphatic bifunctional isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate (IPDI), and aromatic bifunctional isocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate. The NCO group of the bifunctional isocyanate can undergo a crosslinking reaction with the carboxyl group or hydroxyl group of the polymer.
The content of the bifunctional crosslinking agent is preferably in the range of 0.1 equivalent or less with respect to the crosslinking point of the polymer, for example, 1.0 to 3.0 parts by weight with respect to 100 parts by weight of the main polymer.

Here, the material of the base material used when the pressure sensitive adhesive raw material composition is applied to form the pressure sensitive adhesive film has transparency and heat resistance, and inhibits the curing of the ultraviolet curable resin composition. Those having small scattering and absorption in the ultraviolet region near 350 nm to 400 nm are preferable. For example, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polysulfone, polyethersulfone, polystyrene, polyacrylate, polyetheretherketone, polycarbonate, polyolefin such as polyethylene and polypropylene, polyamide, nylon, polyimide , Fluorine such as triacetyl cellulose (cellulose triacetate), cellulose diacetate, poly (meth) acrylic acid alkyl ester, poly (meth) acrylic acid ester copolymer, polymethyl methacrylate, polytetrafluoroethylene and polytrifluoroethylene Resin, polyvinyl chloride, polyvinylidene chloride copolymer, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, cellophane, cellulose film, etc. It can be mentioned. These materials may be used alone or in combination of two or more.
In particular, among the substrates, it is preferable to use polyethylene terephthalate from the viewpoints of heat resistance, ultraviolet light transmittance, and cost.
In addition, it is preferable that the thickness of a base material has 16 micrometers-200 micrometers, and it is still more preferable that it has 50 micrometers-188 micrometers. If the thickness of the substrate is too thin, the handling properties are poor, and if the thickness of the substrate is too thick, it is disadvantageous in terms of cost and handling properties.

The coating apparatus for applying the adhesive raw material composition to the substrate may be any apparatus as long as it has a means for uniformly supplying and applying the adhesive raw material composition on the base material. A device comprising a tank for storing an adhesive raw material composition, a liquid feed pump, piping, a foreign matter removal filter, and a coater head so that the adhesive raw material composition can be supplied and coated on the substrate. Preferred (not shown). The coater head is preferably a die coater, for example.
A thin film layer (coating film) of the pressure-sensitive adhesive raw material composition is formed on one side of the substrate by the coating apparatus. The pressure-sensitive adhesive raw material composition immediately after coating with a coating apparatus is uncured and liquid, and has fluidity suitable for coating.

When the raw material composition for adhesives is a syrup type, it is preferable that the thickness of a coating film is between 0.05-3 mm, More preferably, it is 0.1-2 mm. The thickness of the coating film is approximately equal to the thickness of the pressure-sensitive adhesive layer obtained by photopolymerization. Therefore, the thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive film of the present invention is preferably between 0.05 and 3 mm, more preferably 0.1 to 2 mm.
When the raw material composition for the pressure-sensitive adhesive is a solution type, the thickness of the coating film before drying is thicker than that of the syrup type, and is a number obtained by dividing the thickness of the coating film by the concentration. The thickness of the coating film after drying is the same as that of the syrup type.
If the coating film is too thin, the thickness of the pressure-sensitive adhesive layer is also reduced, so that the impact absorbing performance is deteriorated. Moreover, when the coating film is too thick, it is disadvantageous in that the cost increases.

  In FIG. 2, an example of the manufacturing method of the adhesive film of this invention is shown typically. In the apparatus shown in FIG. 2, the pressure-sensitive adhesive raw material composition is supplied from the die coater 21 onto the substrate 11 to form the coating film 12. Reference numeral 22 denotes a backup roll 22 that is disposed to face the die coater 21 and supports the substrate 11. The base material 11 on which the coating film 12 is formed is transported along the longitudinal direction thereof, and dried in the drying chamber 23 so as to remove the solvent in the coating film 12. On the dried coating film 12, the separator 13 is supplied from the separator supply means 24 onto the coating film 12 and bonded by a nip roll 25.

The temperature in the drying chamber 23 may be a temperature at which the solvent in the coating film 12 is sufficiently volatilized, and is desirably maintained at a temperature at which the polymerizable compound is not thermally polymerized.
The separator supply means 24 includes a roll body around which the separator 13 is wound, a shaft that holds the roll body, and the like.
The nip roll 25 is composed of a pair of rolls that sandwich the base material 11 on which the coating film 12 is formed and the separator 13, and is an apparatus that bonds the two together. It is preferable to provide a pressurizing means for pasting, and at least one of the rolls is preferably made of rubber so that a uniform pressure can be easily applied to the film.

  Examples of the separator include polycarbonate film, polyarylate film, polyethersulfone film, polysulfone film, polyester film, polyamide film, polyimide film, polystyrene film, polyolefin film, norbornene film, phenoxy ether type polymer film, and organic permeation resistance A release film having a release property with a silicone release agent or the like applied to a single-layer or multilayer plastic film such as a gas-resistant film and having a release property at least on one side; Release film that has release properties; Films that have release properties such as fluororesin films and certain polyolefin-based films; And the like. The thickness of the separator is not limited, but is usually 5 to 500 μm, preferably 10 to 100 μm in many cases. The separator is selected according to the pressure-sensitive adhesive used and the intended use (peel strength).

The ultraviolet irradiation device 26 includes a light source unit that generates ultraviolet light and a cooling device that removes heat generated by the light source. The light source part is free of lamp light sources such as high-pressure mercury lamps and metal halide lamps, and light-emitting diodes having a light emission peak in the ultraviolet region, as long as they can obtain an ultraviolet irradiation amount that sufficiently cures the polymerizable compound in the coating film 12. Can be selected.
The coating film 12 polymerizes the polymerizable compound in the coating film 12 by appropriate light irradiation, thereby increasing the cohesive force and expressing adhesiveness.

Moreover, when manufacturing the double-sided adhesive film which does not have a support body like a transfer tape as an adhesive film of this invention, a separator is supplied not only as the separator 13 but as the base material 11 for conveyance, and an adhesive. A layer is formed on the separator.
Further, when producing a double-sided pressure-sensitive adhesive film having pressure-sensitive adhesive layers on both sides of the support as the pressure-sensitive adhesive film of the present invention, coating and drying of the coating liquid and photopolymerization of the coating film are performed simultaneously or sequentially on each side. Can be done.

  After light irradiation for the photopolymerization reaction, curing for the crosslinking reaction is performed. Although the curing method is not particularly limited, for example, an adhesive film wound up on a roll is left under a predetermined temperature and time condition. The curing temperature depends on the type of the crosslinking agent and the like, but is preferably heated (for example, 40 to 80 ° C.) as necessary.

The obtained pressure-sensitive adhesive layer has an adhesive force to glass and acrylic resin when the pressure-sensitive adhesive surface is bonded to an adherend and left in an environment of 23 ° C. and 50% RH for 1 hour and then peeled at a peeling speed of 300 mm / min. Is preferably 10 N / 25 mm or more. In order to obtain such a high adhesive strength, the storage elastic modulus (G ′) at 23 ° C. and 1 Hz of the adhesive constituting the adhesive layer is 1 × 10 ⁴ Pa or more and less than 1 × 10 ⁶ Pa. In the case where high durability is required such as in a test under an environment of 85 ° C. and 95% RH, the pressure is more preferably 5 × 10 ⁴ Pa or more and 5 × 10 ⁵ Pa or less. When the storage elastic modulus is low, the pressure-sensitive adhesive layer is soft and easily deformed, so that it is easy to bond. When the storage elastic modulus is within the above range, the two members (for example, a hard material such as a glass plate or an acrylic plate) are pasted together, the durability after pasting, the adhesive strength, etc. It becomes.

  The pressure-sensitive adhesive film of the present invention can be suitably used as a pressure-sensitive adhesive tape for use in bonding members to various displays such as PDP (plasma display), liquid crystal panel, and organic EL panel.

Hereinafter, the present invention will be specifically described with reference to examples.
<Production of transfer tape>
Transfer tapes of Examples 1 to 15 and Comparative Examples 1 to 5 were produced by the following production method using the pressure-sensitive adhesive raw material composition having the formulation shown in Table 1 below. Moreover, the number average molecular weight (Mn) and the weight average molecular weight (Mw) of each main polymer were measured by the method shown in the following (Molecular weight measuring method).

In Table 1, “2EHA” represents 2-ethylhexyl acrylate, “AA” represents acrylic acid, “HEA” represents 2-hydroxylethyl acrylate, “4HBA” represents 4-hydroxylbutyl acrylate, “Irg651” represents Irgacure (registered trademark) 651. Moreover, the kind of crosslinking agent was shown using the product name quoted in the following manufacturing method, respectively.
Here, the photopolymerization initiator of product name: Irgacure (registered trademark) 651 contains benzyl dimethyl ketal as an active ingredient.
Product name: The epoxy equivalent (g / epoxy group 1 mol) of the bifunctional epoxy crosslinking agent of EX-830 is 268. Moreover, the epoxy equivalent of the bifunctional epoxy crosslinking agent of product name: EX-931 is 172.
The equivalent of the crosslinking agent was calculated by using a carboxyl group as a crosslinking point in an epoxy compound and a carboxyl group and a hydroxyl group as a crosslinking point in an isocyanate.

(Molecular weight measurement method)
Each main polymer is diluted to a concentration of 2%, the mobile phase is measured with a tetrahydrofuran (THF), a flow rate of 0.5 ml / min using a GPC analyzer (Waters Corp .; apparatus name Alliance 2695-2414 RI detector), and the molecular weight is calculated in terms of polystyrene. Was calculated.

Example 1
A mixed solvent solution was prepared by dissolving 90 parts by weight of 2-ethylhexyl acrylate (2EHA) and 10 parts by weight of acrylic acid (AA) in ethyl acetate used as an organic solvent. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 70,000 and a weight average molecular weight of 1,260,000.
Next, 15.0 parts by weight of 4-hydroxylbutyl acrylate (Osaka Organic Materials Co., Ltd .; 4HBA) as monomer B, and polyethylene glycol diglycidyl ether (Nagase ChemteX Corporation) as a bifunctional epoxy crosslinking agent Company: Product name: EX-830) 2.0 parts by weight, alkylphenone photopolymerization initiator (Ciba Japan Co., Ltd .; product name: Irgacure (registered trademark) 651) 0.10 parts by weight Then, the prepared main polymer was added to a solvent solution dissolved in ethyl acetate used as a solvent to prepare an adhesive material composition.
The addition amount of the crosslinking agent is 0.05 equivalent with respect to the crosslinking point (AA carboxyl group) of the polymer.
Using the applicator on the upper surface of a separator (manufactured by Toyobo Co., Ltd .; product name: K1504, thickness 75 μm) using the pressure-sensitive adhesive raw material composition as a base material, the thickness of the pressure-sensitive adhesive layer after drying becomes 200 μm. After coating, the laminate of the pressure-sensitive adhesive layer was produced by drying.
Next, a separator (manufactured by Mitsubishi Plastics Co., Ltd .; product name; MRF, thickness 38 μm) was bonded to the upper surface of the pressure-sensitive adhesive layer of the obtained laminate to produce a pressure-sensitive adhesive laminated film.
Then, using a continuous UV irradiation device that irradiates the substrate with a high-pressure mercury lamp while conveying the substrate, the conveyance speed of the laminated film of the pressure-sensitive adhesive as the substrate so that the irradiation amount is about 200 mJ (wavelength 300 nm to 400 nm), A transfer tape having a pressure-sensitive adhesive layer formed thereon is prepared by performing UV irradiation while adjusting the amount of UV irradiation, causing a photopolymerization reaction using a photopolymerization initiator, curing at 40 ° C. for 7 days or more, and finally forming an adhesive layer. Produced.

(Example 2)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The number average molecular weight of this main polymer was 110,000, and the weight average molecular weight was 253,000.
Next, 15.0 parts by weight of 4HBA, 1.0 part by weight of EX-830, and 0.10 parts by weight of Irgacure (registered trademark) 651 were dissolved in ethyl acetate used as a solvent. The prepared main polymer was added to prepare a pressure-sensitive adhesive raw material composition.
The addition amount of a crosslinking agent is 0.02 equivalent with respect to the crosslinking point of a polymer (carboxyl group of AA).
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Example 3)
A transfer tape was produced in the same manner as in Example 2 except that the pressure-sensitive adhesive raw material composition was prepared with 2.0 parts by weight of EX-830.
The addition amount of a crosslinking agent is 0.04 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).
Example 4
A transfer tape was prepared in the same manner as in Example 2 except that the pressure-sensitive adhesive material composition was prepared with 10.0 parts by weight of 4HBA and 2.0 parts by weight of EX-830.
The addition amount of a crosslinking agent is 0.04 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).

(Example 5)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 120,000 and a weight average molecular weight of 4,350,000.
Next, in a solvent solution in which 5.0 parts by weight of 4HBA, 1.5 parts by weight of EX-830 and 0.05 parts by weight of Irgacure (registered trademark) 651 were dissolved in ethyl acetate used as a solvent, The prepared main polymer was added to prepare a pressure-sensitive adhesive raw material composition.
The addition amount of a crosslinking agent is 0.03 equivalent with respect to the crosslinking point (AA carboxyl group) of a polymer.
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Example 6)
A transfer tape was produced in the same manner as in Example 5 except that 10.0 parts by weight of 4HBA and 2.0 parts by weight of EX-830 were used.
The addition amount of a crosslinking agent is 0.04 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).
(Example 7)
A transfer tape was produced in the same manner as in Example 5 except that 15.0 parts by weight of 4HBA and 2.5 parts by weight of EX-830 were used.
The addition amount of the crosslinking agent is 0.05 equivalent with respect to the crosslinking point (AA carboxyl group) of the polymer.

(Example 8)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 140,000 and a weight average molecular weight of 1,430,000.
Next, in a solvent solution in which 5.0 parts by weight of 4HBA, 1.5 parts by weight of EX-830 and 0.10 parts by weight of Irgacure (registered trademark) 651 were dissolved in ethyl acetate used as a solvent, The prepared main polymer was added to prepare a pressure-sensitive adhesive raw material composition.
The addition amount of a crosslinking agent is 0.03 equivalent with respect to the crosslinking point (AA carboxyl group) of a polymer.
Other than that was carried out similarly to Example 1, and produced the transfer tape.

Example 9
A transfer tape was produced in the same manner as in Example 8 except that 10.0 parts by weight of 4HBA and 2.0 parts by weight of EX-830 were used.
The addition amount of a crosslinking agent is 0.04 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).
(Example 10)
A transfer tape was produced in the same manner as in Example 8 except that 15.0 parts by weight of 4HBA and 2.5 parts by weight of EX-830 were used.
The addition amount of the crosslinking agent is 0.05 equivalent with respect to the crosslinking point (AA carboxyl group) of the polymer.

(Example 11)
A transfer tape was produced in the same manner as in Example 7, except that the crosslinking agent was 2.0 parts by weight of polypropylene glycol diglycidyl ether (Nagase ChemteX Corporation; product name EX-931).
The addition amount of a crosslinking agent is 0.02 equivalent with respect to the crosslinking point of a polymer (carboxyl group of AA).

(Example 12)
A mixed solvent solution prepared by dissolving 86.5 parts by weight of 2EHA, 13 parts by weight of AA, 0.5 parts by weight of 2-hydroxyethyl acrylate (HEA), and ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer.
Next, 15.0 parts by weight of 4HBA, 1.5 parts by weight of isophorone diisocyanate (Mitsui Chemical Polyurethane Co., Ltd .; product name: A-45N) as a crosslinking agent, and 0.05 parts by weight of Irgacure (registered trademark) 651 Was added to the solvent solution dissolved in ethyl acetate used as a solvent, and the prepared main polymer was added to prepare an adhesive raw material composition.
The addition amount of the crosslinking agent is 0.05 equivalent with respect to the crosslinking point of the polymer (carboxyl group of AA and hydroxyl group of HEA and 4HBA).
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Example 13)
A transfer tape was produced in the same manner as in Example 12 except that 2.5 parts by weight of A-45N and 0.10 parts by weight of Irgacure (registered trademark) 651 were used.
The addition amount of the crosslinking agent is 0.08 equivalent with respect to the crosslinking point of the polymer (carboxyl group of AA and hydroxyl group of HEA and 4HBA).
In Examples 12 and 13, the molar ratio between the crosslinking point of polymer A (carboxyl group of AA and hydroxyl group of HEA) and the crosslinking point of polymer B (hydroxyl group of 4HBA) is 1: 0.56. The former has a higher ratio than the latter.

(Example 14)
A mixed solvent solution in which 92 parts by weight of 2EHA and 8 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 90,000 and a weight average molecular weight of 1,260,000.
Next, in a solvent solution in which 17.2 parts by weight of 4HBA, 1.7 parts by weight of EX-830, and 0.06 parts by weight of Irgacure (registered trademark) 651 were dissolved in ethyl acetate used as a solvent, The prepared main polymer was added to prepare a pressure-sensitive adhesive raw material composition.
The addition amount of a crosslinking agent is 0.06 equivalent with respect to the crosslinking point (AA carboxyl group) of a polymer.
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Example 15)
A mixed solvent solution in which 95 parts by weight of 2EHA and 5 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 300,000 and a weight average molecular weight of 1,440,000.
Next, in a solvent solution in which 10.0 parts by weight of 4HBA, 1.5 parts by weight of EX-830, and 0.05 parts by weight of Irgacure (registered trademark) 651 were dissolved in ethyl acetate used as a solvent, The prepared main polymer was added to prepare a pressure-sensitive adhesive raw material composition.
The addition amount of the crosslinking agent is 0.08 equivalent with respect to the crosslinking point of the polymer (AA carboxyl group).
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Comparative Example 1)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 120,000 and a weight average molecular weight of 4,350,000.
Next, the prepared main polymer is added to a solvent solution obtained by dissolving 10.0 parts by weight of 4HBA and 0.05 parts by weight of Irgacure (registered trademark) 651 in a solvent, and then sticking. An agent raw material composition was prepared. In this case, no crosslinking agent is added.
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Comparative Example 2)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 120,000 and a weight average molecular weight of 4,350,000.
Next, the prepared raw material polymer is added to a solvent solution prepared by dissolving 10.0 parts by weight of 4HBA and 2.0 parts by weight of EX-830 in ethyl acetate as a solvent, and then the pressure sensitive adhesive raw material composition The ingredients were prepared.
The addition amount of a crosslinking agent is 0.04 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Comparative Example 3)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 120,000 and a weight average molecular weight of 4,350,000.
Next, the prepared main polymer is added to a solvent solution in which 2.0 parts by weight of EX-830 and 0.05 parts by weight of Irgacure (registered trademark) 651 are dissolved in ethyl acetate used as a solvent. A pressure-sensitive adhesive raw material composition was prepared. In this case, monomer B is not added.
The addition amount of a crosslinking agent is 0.04 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Comparative Example 4)
A mixed solvent solution in which 87 parts by weight of 2EHA and 13 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer. The main polymer had a number average molecular weight of 120,000 and a weight average molecular weight of 4,350,000.
Next, 10 parts by weight of 4HBA, 7.5 parts by weight of EX-830, and 0.05 parts by weight of Irgacure (registered trademark) 651 were dissolved in ethyl acetate used as a solvent. An adhesive raw material composition was prepared by adding the used main polymer.
The addition amount of a crosslinking agent is 0.16 equivalent with respect to the crosslinking point of a polymer (AA carboxyl group).
Other than that was carried out similarly to Example 1, and produced the transfer tape.

(Comparative Example 5)
A mixed solvent solution in which 80 parts by weight of 2EHA and 20 parts by weight of AA were dissolved in ethyl acetate used as an organic solvent was prepared. Using this mixed solvent liquid, a solution polymerization reaction was performed while refluxing the organic solvent at the boiling point to prepare a main polymer.
Next, in a solvent solution obtained by dissolving 15 parts by weight of 4HBA, 2.0 parts by weight of EX-830, and 0.10 parts by weight of Irgacure (registered trademark) 651 in ethyl acetate used as a solvent, The prepared main ingredient polymer was added to prepare an adhesive raw material composition.
The addition amount of a crosslinking agent is 0.03 equivalent with respect to the crosslinking point (AA carboxyl group) of a polymer.
Other than that was carried out similarly to Example 1, and produced the transfer tape.

<Testing method for adhesive tape>
Using the pressure-sensitive adhesive tapes (transfer tapes) of Examples 1 to 15 and Comparative Examples 1 to 5, a pasting sample was prepared, and a bubble confirmation test, a cloudiness confirmation test, a durability test, and an adhesive strength after pasting. Measurement and storage modulus measurement were performed.

(Bubble confirmation test after bonding)
Using a bonding device (Climb Products Co., Ltd .; product name SE320), a 50 mm × 50 mm adhesive tape is bonded to a 2 mm thick glass plate of 75 mm × 100 mm size, and then an acrylic plate is attached to the opposite surface of the adhesive tape. Pasted. The appearance after bonding was visually confirmed from the side of the acrylic plate, and the case where bubbles could be confirmed was evaluated as (x), and the case where the bubbles could not be confirmed was evaluated as (◯).

(White turbidity confirmation test)
The bonded product produced in the bubble confirmation test was put in an environment of 85 ° C. × 95% RH and taken out after 12 hours. Thereafter, it was left in an environment of 23 ° C. and 50% RH, and the appearance change was visually confirmed. A cloudy product was evaluated as (x), and a sample in which cloudiness was not confirmed was evaluated as (◯).
Moreover, the adhesive tape obtained by Example 6 and the comparative example 2 was thrown into the oven adjusted to the conditions of 85 degreeC x 95% RH as heat-and-moisture-proof environment test conditions, and it took out after holding | maintaining for 12 hours. The haze value of the tested sample was measured from immediately after taking out from the oven until 180 minutes elapsed, and the change in haze value after taking out from the obtained high temperature and high humidity test is shown in FIG.
The haze value was measured using a haze meter (manufacturer: Nippon Denshoku Co., Ltd., model: Haze Meter, NDH2000).

(Durability test and vacuum bonding)
An adhesive tape of 50 mm x 50 mm is bonded to a 2 mm thick glass plate of 75 mm x 100 mm size, and then a 0.8 mm thick acrylic plate (Mitsubishi Resin; product name: MR-200) is attached to the opposite side of the adhesive tape. Bonding was performed in a vacuum environment. The bonding conditions were such that when the degree of vacuum reached 1.0 × 10 ¹ Pa, pressing was performed at a pressure of 3.0 MPa for 20 seconds. At this point in time, it was confirmed that the laminating was completed without bubbles. Next, autoclaving was performed at 60 ° C. × 0.5 MPa × 30 minutes to complete a sample of the bonded product.
In the durability test, a sample of the produced bonded product is put into a high temperature and high humidity environment of 85 ° C. dry, 60 ° C. × 90% RH, 85 ° C. × 95% RH, taken out after 12 hours, and visually confirmed. And those with floating / peeling were evaluated as (×). At this time, the sample without floating / peeling was put in for another 500 hours, and after taking it out, visual confirmation was carried out. The sample with floating / peeling was evaluated as (X), and the sample without float was evaluated as (O).

(Durability test and atmospheric pressure bonding)
A 50 mm × 50 mm adhesive tape was bonded to a 75 mm × 100 mm 2 mm thick glass plate, and then a 0.8 mm thick glass plate was bonded to the opposite surface of the adhesive tape under atmospheric pressure. SE320 made by Climb Products was used for pasting. At this time, autoclaving was performed at 60 ° C. × 0.5 MPa × 30 minutes for the sample that could be confirmed to be neatly bonded without bubbles, and a sample of the bonded product was completed.
In the durability test, a sample of the produced bonded product is put into a high-temperature and high-humidity environment of 85 ° C. × 95% RH, taken out after 12 hours, and checked visually. (×) was evaluated. At this time, the sample without floating / peeling was put in for another 500 hours, and after taking it out, visual confirmation was carried out. The sample with floating / peeling was evaluated as (X), and the sample without float was evaluated as (O).

(Storage elastic modulus measurement)
A plurality of pressure-sensitive adhesive tapes were stacked and bonded, and autoclaving at 60 ° C. × 0.5 MPa × 30 minutes was performed to prepare a sample for a dynamic viscoelasticity test having a thickness of 1 mm. This sample was subjected to a dynamic viscoelasticity test using a shear type rheometer (AntonPaar; apparatus name: MCR301) in a linear region at a frequency of 1 Hz. The storage modulus was measured by reading the value at a room temperature of 23 ° C. under a temperature range of −40 ° C. to + 150 ° C. and a temperature increase rate of 3 m / min.

(Adhesive strength measurement)
One separator of the adhesive tape (here transfer tape) is peeled off, one side of the adhesive layer is bonded to a 38 μm thick polyethylene terephthalate (PET) film, and the other separator is peeled off to reverse the adhesive layer. After the surface was bonded to an adherend (glass plate or acrylic plate), it was allowed to stand in an environment of 23 ° C. and 50% RH for 1 hour, and then peeled at a peeling speed of 300 mm / min, and the 180 ° peel strength was measured.

<Test results>
The results of the above test are shown in Table 2.

(Result of air bubble confirmation test after bonding)
About Examples 1-15, it has confirmed that it can bond without a bubble. In Comparative Examples 1 to 4, it was confirmed that bonding could be performed without bubbles. In Comparative Example 5, bubbles were confirmed. This is presumably because, in Comparative Example 5, the ratio of AA in the main polymer is large, the resin is hard, and the followability to the adherend is poor.

(Result of cloudiness confirmation test of adhesive tape)
About Examples 1-15, cloudiness was not able to be confirmed. In Comparative Examples 1, 4, and 5, no cloudiness could be confirmed. In Comparative Examples 2 and 3, cloudiness was confirmed.
In Comparative Example 2, since no photopolymerization initiator is introduced, the monomer B does not polymerize even when UV irradiation is performed. In Comparative Example 2, since it was not a pressure-sensitive adhesive having an effect of improving white turbidity, it was confirmed that polymerizing monomer B was effective in improving white turbidity.
Moreover, since the monomer B does not exist in the comparative example 3, although a photoinitiator reacts by performing UV irradiation, the polymer of the monomer B which has a cloudiness improvement effect is not produced | generated. Since it became cloudy in Comparative Example 3, it was confirmed that the presence of the polymerized monomer B was important.
Moreover, in the graph which shows the change of the haze value after taking out from the high temperature high humidity test of FIG. 3, Example 6 which concerns on the adhesive tape of this invention is taken out from the oven immediately after taking out from the oven of a high temperature high humidity test. It can be seen that even after 60 minutes, the haze value has not changed at all, and has excellent white turbidity prevention performance.
On the other hand, in Comparative Example 2, the haze value increased to about 11% as the maximum value within a few minutes immediately after taking out from the oven of the high temperature and high humidity test, and then the haze value gradually decreased with the passage of the standing time. It can be seen that the cloudy state continues for 120 minutes or longer.
This evaluation is a change that occurs when separators or resin films such as polyethylene terephthalate (PET) are used. However, the timing of cloudiness is the same for samples such as glasses with poor gas permeability or acrylic plates and glasses. However, it can take several days for the cloudiness to disappear.
In addition, any cloudiness generated in the heat and humidity resistance test was allowed to stand at room temperature for several hours, and the cloudiness disappeared and became transparent.

(Durability test results)
In the case of the conditions of 85 ° C. dry and 60 ° C. × 90% RH, Examples 1 to 15 include both atmospheric pressure bonding using an acrylic plate as an adherend and vacuum bonding using a glass plate as an adherend. In, floating and peeling by visual observation could not be confirmed. Also in Comparative Example 2, no floating or peeling by visual observation could be confirmed. In Comparative Examples 1 and 3 to 5, the floating / peeling by visual observation was confirmed.
In the case of the conditions of 85 ° C. × 95% RH, in Examples 1 to 13, in the atmospheric pressure bonding using an acrylic plate as an adherend or in the vacuum bonding using a glass plate as an adherend, No floating or peeling due to In Comparative Examples 1-5, the floating and peeling by visual observation were confirmed.
In Comparative Example 1, since there is no crosslinking agent, crosslinking is insufficient and it is considered that heat resistance cannot be imparted.
In Comparative Example 2, it is considered that the monomer B is not polymerized.
In Comparative Example 3, the photopolymerization initiator is considered to be a problem.
In Comparative Example 4, since the amount of the crosslinking agent is excessive, it becomes too hard as an adhesive tape, and it is considered that the comparative example 4 is not able to follow the deformation of the adherend and peels off.
In Comparative Example 5, since the amount of acrylic acid is too large and the adhesive tape is too hard, it is considered that the acrylic tape was peeled off without being able to follow the deformation of the acrylic plate. In addition, in the case of atmospheric pressure bonding, bubbles will enter (see the bubble confirmation test after bonding above), but it disappears temporarily in the autoclave, but it re-aggregates due to the introduction of environmental test. It is also considered that foaming occurs.

(Results of molecular weight distribution measurement)
It is said that the molecular weight of the pressure-sensitive adhesive tape for optical use is preferably a high molecular weight. This is because it is said that when the molecular weight is large, the heat resistance tends to improve and the weather resistance test proceeds in a good direction.
From Example 1, when the monomer ratio of the main agent is 2EHA / AA = 90/10, it seems that Mw is 1 million or more and is good. From the comparison of the results of Examples 2 to 11 and Comparative Example 6, it is considered that a material having an Mw of 1 million or more is more preferable when the monomer ratio of the main agent is 2EHA / AA = 87/13. In the case of 2EHA / AA = 92/8 in Example 14 and 2EHA / AA = 95/5 in Example 15, the Mw is 1 million or more. Therefore, it is considered that a preferable range regardless of the monomer ratio in the main agent is a range where Mw is 1 million or more, and more preferably exceeds 1.2 million.
If the molecular weight is too large, the viscosity is too high and the processability is deteriorated. It is thought that this upper limit can be further widened by devising the coating method such as raising the temperature of the paint, but when applying at room temperature, the material with an Mw of less than 5 million used in Examples 1-11, 14 and 15 Is considered preferable.

(Results of storage modulus measurement)
In order to satisfy the durability of 85 ° C. dry and 60 ° C. × 90% RH, the elastic modulus (unit Pa) of the pressure-sensitive adhesive tape may be 10 ⁴ to 10 ⁵ order as in Examples 1-15. However, it can be seen that the elastic modulus is preferably on the order of 10 ^{5 as in} Examples 1 to 13 under the environment of 85 ° C. × 95% RH where the deformation of the acrylic plate becomes large.
When softening the adhesive tape 10 ^four orders as in Examples 14 and 15, although compatibility is better bonded to the adherend, it is necessary to reduce the amount of acrylic acid main agent. When the amount of acrylic acid is reduced, the adhesive strength to the adherend is lowered, and it is considered that floating / peeling occurred in an environment of 85 ° C. × 95% RH. Since the place where it peels becomes the interface between the glass and the adhesive tape, it is considered that the low adhesive strength of the glass is a problem.
Conversely, when the storage elastic modulus is on the order of 10 ⁶ as in Comparative Example 5, the bonding property to the adherend deteriorates.
From this, about the bubble after bonding, the elastic modulus is preferably 10 ⁵ order or less. From the viewpoint of durability, if it is 85 ° C. dry, 60 ° C. × 90% RH, 10 ⁴ to 10 ⁵ order, 85 ° C. × 95 if you need high durability of RH%, preferably from 10 ⁵ order, considered more preferably 10 ⁵ orders early.
The storage elastic modulus (G ′) depends largely on the composition of the main agent, particularly the blending ratio of acrylic acid, but there is a possibility that the storage elastic modulus (G ′) will change greatly depending on the amount of crosslinking agent added. However, in the case of the same monomer composition with the blending ratio of the cross-linking agent according to the present invention, the order is not changed so much, the part having no actual measured value (the part indicated as “(estimated)” in Table 1) is the same composition product. The elastic modulus of the same order as, for example, about 1 × 10 ⁵ to 2 × 10 ⁵ when referring to Examples 1, 6 and Comparative Example 5, and if not, at least 5 × 10 ^{4 to} 5 × 10 ⁵ It is thought that it is within the range.

(Results of adhesive strength measurement)
If the adhesive strength is not high to some extent, the glass plate or acrylic plate, which is the adherend during the durability test, will peel off due to deformation. From the results of Examples 1 to 15, it can be seen that durability is good when it is 10 N / 25 mm or more for glass and 10 N / 25 mm or more for acrylic plate.

  From the above results, the monomer ratio of polymer A, which is the main component of the pressure-sensitive adhesive layer, the amount of monomer B added, the number and amount of functional groups of the crosslinking agent, and the amount of photopolymerization initiator are shown in the claims of the present invention. By making it within the range, it is possible to prevent white turbidity when being put in and taken out in a high temperature and high humidity environment, and it is easy to bond hard materials such as glass and glass / acrylic plates, and even in a high temperature, high temperature and high humidity environment. A highly durable adhesive film without appearance defects such as floating and peeling can be produced.

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Adhesive layer, 3 ... Separator, 5 ... Single-sided adhesive tape, 6 ... Transfer tape, 11 ... Substrate or separator to be conveyed, 12 ... Coating film, 13 ... Separator, 21 ... Die coater, 22 ... backup roll, 23 ... drying chamber, 24 ... separator supply means, 25 ... nip roll, 26 ... ultraviolet irradiation device.

Claims (6)

A method for producing a pressure-sensitive adhesive composition comprising an acrylic polymer containing a hydroxyl group as a functional group,
At least the following steps (1) to (3)
(1) A polymer production process for obtaining a main polymer using a mixed solvent liquid containing at least one kind of acrylic monomer, wherein at least one kind of acrylic monomer having an ester group is 85 to 95 parts by weight, A step of obtaining a main polymer polymerized from a monomer in which at least one of acrylic monomers having a carboxyl group contains 5 to 15 parts by weight;
(2) The main polymer is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer with at least one kind of hydroxyl group-containing (meth) acrylate monomer, photopolymerization initiator, and polymer. Adding an amount of a bifunctional cross-linking agent, and preparing a pressure-sensitive adhesive raw material composition containing these as essential components,
(3) A step of obtaining a pressure-sensitive adhesive composition by performing a polymerization reaction by light irradiation and a crosslinking reaction by curing using the raw material composition for pressure-sensitive adhesives,
Are manufactured in the order of (1)-(3), The manufacturing method of the adhesive composition characterized by the above-mentioned. A method for producing an adhesive film comprising an adhesive layer comprising an acrylic polymer containing a hydroxyl group as a functional group,
At least the following steps (1) to (4)
(1) A polymer production process for obtaining a main polymer using a mixed solvent liquid containing at least one kind of acrylic monomer, wherein at least one kind of acrylic monomer having an ester group is 85 to 95 parts by weight, A step of obtaining a main polymer polymerized from a monomer in which at least one of acrylic monomers having a carboxyl group contains 5 to 15 parts by weight;
(2) The main polymer is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer with at least one kind of hydroxyl group-containing (meth) acrylate monomer, photopolymerization initiator, and polymer. Adding an amount of a bifunctional cross-linking agent, and preparing a pressure-sensitive adhesive raw material composition containing these as essential components,
(3) A process of forming the pressure-sensitive adhesive coating film by applying and drying the pressure-sensitive adhesive raw material composition on the base material or separator of the pressure-sensitive adhesive film,
(4) A step of obtaining a pressure-sensitive adhesive layer by subjecting the pressure-sensitive adhesive coating film to a polymerization reaction by light irradiation and a crosslinking reaction by curing;
Are manufactured in order of (1)-(4), The manufacturing method of the adhesive film characterized by the above-mentioned. (A) A main polymer polymerized from a monomer containing at least one acrylic monomer having an ester group in an amount of 85 to 95 parts by weight and at least one acrylic monomer having a carboxyl group in an amount of 5 to 15 parts by weight. : 100 parts by weight;
(B) at least one kind of hydroxyl group-containing (meth) acrylate monomer: 5 to 20 parts by weight;
(C) Photopolymerization initiator: 0.01 to 0.5 parts by weight;
(D) 1.0 to 3.0 parts by weight of the bifunctional crosslinking agent, which is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer;
As an essential component, and the molecular weight distribution of the main polymer is 70,000 or more in number average molecular weight (Mn) and 1 million or more in weight average molecular weight (Mw) . (A) A main polymer polymerized from a monomer containing at least one acrylic monomer having an ester group in an amount of 85 to 95 parts by weight and at least one acrylic monomer having a carboxyl group in an amount of 5 to 15 parts by weight. : 100 parts by weight;
(B) at least one kind of hydroxyl group-containing (meth) acrylate monomer: 5 to 20 parts by weight;
(C) Photopolymerization initiator: 0.01 to 0.5 parts by weight;
(D) 1.0 to 3.0 parts by weight of the bifunctional crosslinking agent, which is 0.02 equivalents or more and 0.1 equivalents or less with respect to the crosslinking point of the polymer;
As an essential component, and the molecular weight distribution of the main polymer is 70,000 or more in number average molecular weight (Mn) and 1 million or more in weight average molecular weight (Mw) A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer having a thickness of 0.05 to 3 mm obtained by applying a polymerization reaction by light irradiation and a crosslinking reaction by curing after coating on a substrate or a separator. The pressure-sensitive adhesive layer has an adhesive strength of 10 N against glass and acrylic resin when the pressure-sensitive adhesive surface is bonded to an adherend and left at 23 ° C. and 50% RH for 1 hour and then peeled at a peeling speed of 300 mm / min. The storage elastic modulus (G ′) at 23 ° C. and 1 Hz of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is 1 × 10 ⁴ Pa or more and less than 1 × 10 ⁶ Pa. The pressure-sensitive adhesive film according to claim 4.   The pressure-sensitive adhesive film according to claim 4 or 5, wherein the pressure-sensitive adhesive tape is used for bonding a member to a display.

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