TWI545018B - Stripping film bonding double - sided adhesive tape and manufacturing method thereof - Google Patents

Description

Release film bonding double-sided adhesive tape and manufacturing method thereof

The present invention relates to a release film-bonding double-sided adhesive tape and a method of manufacturing the same. The release film-bonding double-sided adhesive tape is a release film which is bonded to both surfaces of a double-sided adhesive tape which is a cured product of an ultraviolet-curable adhesive. The release film-bonding double-sided adhesive tape can exhibit good adhesive properties even when the thickness of the adhesive layer is thick, and is particularly suitable for use in the subsequent step of the optical member. The above-described production method is a simple and simple method for curing the ultraviolet curing adhesive (the ultraviolet irradiation step) for bonding the above-mentioned release film to the double-sided adhesive tape.

In industrial applications, particularly in optical applications such as personal computers, hard disks, and the like, liquid crystal displays, touch panels, and the like, double-sided adhesive tapes are widely used for the subsequent attachment of the members.

The above double-sided adhesive tape is usually supplied by a double-sided adhesive tape which is a self-adhesive adhesive layer of a double-sided adhesive tape and a release film which is bonded to both surfaces thereof. This release film is bonded to the double-sided adhesive tape in addition to having a shape in which the adhesive body is bonded before use, and the peeling film on both sides is peeled off. The release film-bonding double-sided adhesive tape is formed by, for example, applying a composition for forming an adhesive to the release surface of the one-side release film, and then curing the coating film into an adhesive layer by heat or ultraviolet rays, and then on the opposite side. After the release film is bonded, it is produced by a step of winding into a roller shape (Japanese Patent Laid-Open Publication No. 2010-72471).

When the double-sided adhesive tape is bonded by using a release film, for example, when the liquid crystal display unit of the liquid crystal display is attached to the casing, the release film is bonded to the double-sided adhesive tape in accordance with the outer frame shape press processing of the liquid crystal display unit. On the other hand, in the case of a touch panel, in addition to the purpose of providing a cushioning property between the transparent conductive film (for example, a film of ITO) and the outermost layer of a scratch-resistant film (for example, a PET film), An example of using a double-sided adhesive film. At this time, the display area of the touch panel is entirely covered with a peeling film.

The demand for double-sided adhesive tapes in the field of liquid crystal related as described above has gradually increased in recent years. In particular, the use of touch panels has been significantly expanded. The screen size of the touch panel has been increasing year by year. In the above-described large-sized touch panel, since the cushioning property is required between the transparent conductive film and the scratch-resistant film, the thickness of the double-sided adhesive tape (adhesive layer) tends to be thicker.

For this reason, since the thickness of the application can be limited by one application step, when the thickness of the adhesive is increased, a plurality of application steps must be performed. Further, there is a case where it is difficult to completely cure the thickness of the adhesive layer after application. In order to completely cure the adhesive layer, it is necessary to adjust the heating temperature and heating time in the case of a thermosetting adhesive. On the other hand, in the case of the ultraviolet curable adhesive, it is necessary to perform a plurality of ultraviolet irradiation steps, so that the adhesive layer forming step is complicated and the cost is problematic.

The release film is bonded to the base material of the release film of the double-sided adhesive tape, and a polyethylene terephthalate (PET) film is suitably used from the viewpoint of heat resistance and surface smoothness. Stripping using a thermosetting adhesive layer with a PET film In the case where the release film of the double-sided adhesive tape is bonded to the film, it is particularly preferable to reduce the deformation of the base film in the heat curing step of the adhesive layer as much as possible.

However, when a PET film is used as a release film of a double-sided adhesive tape as a release film having an ultraviolet-curable adhesive layer, there is a problem in the curing step of the adhesive. That is, since PET has a property of absorbing ultraviolet rays having a wavelength of 300 nm or less, ultraviolet curing of the adhesive is hindered. In particular, when the thickness of the adhesive layer becomes thicker, there is a case where the curing reaction of the adhesive layer cannot be completed by one ultraviolet irradiation step. In the above case, for example, a method of delaying the irradiation speed of the ultraviolet irradiation line to increase the irradiation time, a method of performing the ultraviolet irradiation step after the ultraviolet irradiation step, and a method of performing the ultraviolet irradiation step again after the ultraviolet irradiation step; After the release film is bonded to both sides, the release film on the opposite side is peeled off, and the surface is again subjected to ultraviolet irradiation to expect complete curing. Any of these methods will increase the step time, the operation is complicated, and the cost is not ideal.

However, when the double-sided adhesive tape is bonded by a release film, the peeling film which peels a single surface is used, and the peeling film which peels a single surface after peeling after adhering to an adhering body is used, but the peeling film of the peeling film is peeled. The surface of the adhesive remaining is not constant, or there may be cases where the adhesive layer is damaged.

In view of the above, Japanese Laid-Open Patent Publication No. 2010-150378 proposes a technique in which two kinds of adhesives having different adhesive strengths are laminated, and the adhesion to the front and back surfaces of the adhesive layer is provided to solve the above problems. However, in this method, it is necessary to carry out the application step and the curing step of the adhesive layer in two stages, and there is a possibility that the foreign matter is mixed or the interlayer is uneven between the adhesive layers. Good occasions.

As described above, it is possible to suitably apply a double-sided adhesive tape to a release film for use in an optical component, and in particular, a release film-bonded double-sided adhesive tape having a thick ultraviolet-curable adhesive layer and a method for producing the same It has not been proposed in the past.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a release film bonded to a double-sided adhesive tape formed by laminating a release film on both surfaces of a double-sided adhesive tape comprising a cured product of an ultraviolet-curable adhesive. It is shown that even when the thickness of the adhesive layer is thick, it does not cause good adhesion characteristics due to ultraviolet irradiation and hinders the curing reaction, and can be suitably used for a release film for optical use, a double-sided adhesive tape, and a release film-attached double An easy way to apply adhesive tape.

According to the present invention, the first object and an advantage of the present invention are the first aspect of the present invention, in which a release film is bonded to both surfaces of a double-sided adhesive tape comprising a cured product of an ultraviolet-curable adhesive, and the release film is formed of a resin. The surface of the material film on the bonding surface side has a release layer, and the resin constituting at least one of the release films bonded to both surfaces of the double-sided adhesive tape is a release film-bonded double film characterized by a polyolefin resin. The adhesion is achieved.

The above object and advantages of the present invention, and a second method for producing the above-mentioned release film bonded double-sided adhesive tape, according to the above polyolefin resin a first release film having a release layer on the base film; an ultraviolet-curable adhesive layer; and a second release film having a release layer on the base film formed of a resin, which are laminated in a layered manner, and The laminate is achieved by the above-described method characterized by at least an ultraviolet irradiation step of irradiating ultraviolet rays from the first release film side.

The release film-bonding double-sided adhesive tape of the present invention is formed by laminating a release film on both surfaces of a double-sided adhesive tape comprising a cured product of an ultraviolet-curable adhesive. Each of the two release films has a release layer on the surface of the base film of the resin on the bonding surface side.

In the present specification, the "adhesive layer" composed of the "cured material of the ultraviolet curable adhesive" is a "double-sided adhesive tape". In the present specification, the three terms are used separately for the sake of simplicity, but the same means the same. Although the release film is attached to both sides of the double-sided adhesive tape, the "release film is attached to the double-sided adhesive tape" in the present specification.

Hereinafter, each portion of the release film-attached double-sided adhesive tape constituting the present invention will be described in order.

<Substrate film>

The base film of the release film of the present invention is composed of a resin.

[Resin constituting the substrate film]

The release film of the present invention is bonded to the double-sided adhesive tape, and the release film is present 2 sheets, but one of the substrate films is made of a polyolefin resin. The polyolefin resin constituting the base film of the present invention may, for example, be a homopolymer of ethylene, a homopolymer of propylene, a copolymer of ethylene and another olefin, a copolymer of propylene and another olefin, or a mixture thereof. The above-mentioned olefin is preferably an α-olefin having 4 or more carbon atoms, and specific examples thereof include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 1- It is preferred to use one or more selected from the group consisting of terpenes, 1-anthracene, and 4-methyl-1-pentene.

The polyolefin resin is one or more kinds of polyethylene resins selected from high density polyethylene resin (HDPE), low density polyethylene resin (LDPE), and linear low density polyethylene (LLDPE), or homopolymerization of propylene. And a polypropylene-based resin selected from the group consisting of a copolymer of propylene and another α-olefin, or a mixture thereof, or a polypropylene-based resin or a polypropylene-based resin. A mixture with a polyethylene resin is preferred.

The polypropylene resin is preferably a melt flow rate (MFR) of from 1 to 30 g/10 min measured at 230 ° C based on JIS K 7210, and more preferably from 3 to 10 g/10 min. The melting point of the polypropylene resin is preferably 125 ° C or more, and more preferably 125 to 165 ° C.

From the above viewpoints, the copolymer ratio of the other α-olefin of the polypropylene resin is preferably 30% by weight or less and 20% by weight or less based on the total weight of the polypropylene as the monomer and the other α-olefin. Better. The above-mentioned polypropylene-based resin, especially a homopolymer of polypropylene, is most suitable because it is easy to find high transparency and high heat resistance, and it has few fish eyes when it is used as a film.

When a mixture of a polypropylene resin and a polyethylene resin is used as the polyolefin resin constituting the base film of the present invention, the content ratio of the polyethylene resin is preferably 40% by weight or less, based on the total weight of the two. It is 30% by weight or less, but it is preferably from the viewpoint of high heat resistance and when the film is used to reduce fish eyes.

The release film-attached double-sided adhesive tape of the present invention has two release films, and at least one of the base film is made of the above-mentioned polyolefin resin. The base film of the other release film may be composed of a polyolefin resin as described above, or may be composed of a resin other than the above. The resin other than the polyolefin resin which can be used herein is preferably a substrate film material which is used in a conventional release film, such as PET, polyethylene terephthalate, polycarbonate or the like.

In the release film of the present invention, in the double-sided adhesive tape, the resin of the base film of the release film forming the front and back is a polyolefin resin, but the curing step of the ultraviolet-irradiated adhesive layer can be carried out from the front and back. It is better to carry out either side of the face, or to advance the step from both sides.

The base film of the release film on both the front and back sides may be composed of the same type of polyolefin resin, or may be composed of different types of polyolefin resin. However, from the viewpoint of more effectively finding the above advantages, at least one of them is preferably composed of the above-mentioned polypropylene resin, or both of the front and back are preferably made of a polypropylene resin.

[Colorant]

The release film of the present invention is applied to the double-sided adhesive tape as described later, and the double-sided adhesive tape is attached. The peeling force of the release film of the tape is preferably different from the front and back. At this time, in order to easily discriminate the release film and the front and back of the double-sided adhesive tape, it is preferable that at least one of the release films of the front and back is a colored film.

A method of coloring a release film, for example, a method of obtaining a colored film by printing on a surface of a substrate film is known. However, according to this method, in the formation of the film and other steps, there are a plurality of steps necessary for printing, which is economically unsatisfactory. In the step of applying a release agent to the base film (described later), an organic solvent is usually used, and the ink printed on the surface of the base film is dissolved in the organic solvent. Further, it is technically difficult to print thin and uniform on the surface of the film, and there is a possibility that printing unevenness is high. Therefore, it is not suitable for use in which the optical inspection is necessary in a state in which the release film is unilaterally left.

Another method for coloring the release film proposes that, in the production of the biaxially stretched resin film, the application of the application liquid containing the colorant on the film after the longitudinal stretching is performed, drying, and then extending in the lateral direction, and obtaining a non-printing unevenness by a step A method of color film (Japanese Patent Laid-Open Publication No. 2000-25108). However, according to this technique, there is still a problem that the surface printing ink is dissolved in an organic solvent and cannot be solved.

On the other hand, the method of blending the colorant with the resin constituting the base film does not cause uneven coloration, and there is no problem of elution of the printing ink dissolved in the organic solvent when the release agent is applied to the base film, and it is easy to obtain appropriate The colored release film.

The coloring agent used in the present invention is preferably a pigment, from the viewpoint of having a small problem of discoloration. The pigment here is in organic pigments and inorganic pigments. In the above, one or more kinds of the pigments generally used as the coloring agent for plastics can be appropriately selected. Examples of the above organic pigments include, for example, an azo pigment, a phthalocyanine pigment, an aniline pigment, and a quinacridone pigment, and the inorganic pigment is, for example, titanium oxide, red iron oxide, ultramarine blue, carbon black, cobalt oxide, or the like. One or more of these are used.

Among these pigments, in particular, an organic pigment is used, and in addition to the secondary coagulum of the pigment itself, the occurrence of defects such as fish eyes is small, and it is suitable because of good dispersibility to the resin.

The mixing ratio of the resin coloring agent is appropriately determined depending on the thickness of the base film, etc., but when the transparency (transparency) of the final release film is considered, it is 0.01 to 5 parts by weight with respect to 100 parts by weight of the resin. Good, and better with 0.05~3 weight. When the mixing ratio is less than 0.01 parts by weight, the hue is unclear, so that it is difficult to recognize whether or not the bonded release film has been colored. On the other hand, when the mixing ratio is more than 5 parts by weight, not only the transparency (transparency) of the release film is insufficient, but also the secondary condensation of the colorant itself may cause defects such as fish eyes. Obvious occasions, in addition to not practical, will also cause economic disadvantages such as large cost burden of coloring agents.

The method of blending the resin of the base film of the release film with the above-mentioned coloring agent may, for example, be a method of directly mixing a coloring agent on the particles of the resin, and once the resin and the coloring agent are used to produce a main compound containing a coloring agent at a high concentration. The method of blending the resin particles and the like can be carried out by a conventionally appropriate method without particular limitation. However, when considering the dispersion state of a good coloring agent and minimizing the adhesion to the coloring agent of the molding machine, the main rubber compound is used. The method is better.

[Surface smoothing agent]

The release film of the present invention is bonded to the base film of the release film of the double-sided adhesive tape, and the surface smoothness thereof is extremely high. Therefore, after the production of the base film, the surface of the adhesive layer formed after the step of forming the release layer and the step of laminating the adhesive layer becomes very smooth. However, in order to obtain a higher degree of smoothness of the surface of the adhesive layer, the substrate film may have a surface smoothing layer on its surface.

When the base film has a smooth surface layer, the base film preferably has a surface smooth layer on at least the surface on the side of the release layer, and may have a surface smooth layer on both sides.

The surface smoothing layer has a function of burying minute irregularities formed on the surface of the base film to smooth it, but may have other functions. Here, the other functions of the surface smoothing layer include, for example, an intermediate coating function, a hard coat function, an electrostatic prevention function, and the like. The base film has a surface smoothing layer having the above-described static electricity prevention function, and it is preferable to use a known release film to bond the double-sided adhesive tape to avoid problems due to various types of static electricity.

The thickness of the surface smoothing layer is preferably 0.1 to 5.0 μm, more preferably 0.5 to 3.0 μm. By setting the thickness of the surface smoothing layer in the above range, it is possible to effectively bury the fine unevenness of the surface of the film which is caused by crystallization in the production of the base film, and it is preferable to obtain a high degree of surface smoothness easily and at low cost.

[Characteristics of Substrate Film]

The release film of the present invention is bonded to the base film of the release film of the double-sided adhesive tape, and the step of applying the release agent and the step of laminating the ultraviolet-curable adhesive ensure that heat and relative tension are applied to the substrate film. From the viewpoint of dimensional stability, the tensile elastic modulus is preferably 700 MPa or more in terms of longitudinal and lateral directions, and more preferably 900 MPa or more.

The thickness of the base film should be appropriately set according to the thickness of the adhesive layer, the area and shape of the product after press working, etc., but it is preferably 10 to 200 μm, more preferably 20 to 150 μm, especially 40 to 120 μm. good. Here, when the thickness of the base film is too thin, the step of applying the release agent and the heat of the step of laminating the adhesive may cause wrinkles due to "heat load" on the film, and may not be used as a product. occasion. Especially in the case where the thickness of the adhesive layer is thick, this tendency is remarkable. On the other hand, when the thickness of the base film is too large, the flexibility is insufficient, and there is a case where appearance defects such as wrinkles and projections are likely to occur during the production of the wound body, which is not preferable.

[Method for Producing Substrate Film]

The base film of the release film of the double-sided adhesive tape to which the release film of the present invention is bonded is composed of the above-mentioned resin film, and may be produced by any method as long as it has the above characteristics.

The method for producing the base film (resin film) may, for example, be a gas processing method, a casting method, or a method of stretching over a single axis or the like. Among these, the heat shrinkage of the non-extended resin film obtained by the casting method is small, and the step of applying the release agent The step of laminating the adhesive layer may be suitable for use in the case where the thermal dimensional change is small.

The base film of the present invention may have a single layer structure or a multilayer structure of two or more layers. The method in which the base material film has a multilayer structure is, for example, a coextrusion method represented by a multi-manifold method or an oil-supply sleeve method; an in-line lamination method; after each layer is produced in a single layer, it is laminated by an adhesive layer or the like by dry lamination or the like. Method, etc.

When the base film is a colored film, the base film is a film of a laminate having at least three layers, and the layer in which the colorant is blended is a layer other than the outermost layer, that is, a sample in which only the intermediate layer is blended with a colorant. The state is more preferable because it prevents the problem that the coloring agent dissolves in the organic solvent when the adhesive layer is laminated, or the molding machine, particularly the problem that the coloring agent adheres to the inside of the mold.

When the base film has a smooth surface layer, the base film is preferably coated with a suitable coating agent on the surface of the resin film formed as described above, and can be produced by the self-leveling effect of the coating agent. Here, a commercially available product can be used as a coating agent. A commercially available product of a coating agent is, for example, a product name: UVH-D003 (manufactured by Idemitsu Technofine Co., Ltd.). The coating agent UVH-D003 has an antistatic function in addition to the surface smoothing function. The viscosity of the paint is preferably adjusted from 1 to 10,000 cp from the viewpoint of effectively finding the self-leveling effect.

The base film of the present invention is applied to the release agent by applying a surface treatment in addition to the surface on the side of the application of the release agent, in addition to the surface treatment on the side of the application of the release agent, from the viewpoint of further improving the adhesion to the release agent applied thereto. It is better. The surface treatment may be, for example, a corona discharge treatment or a flame heat (flame) treatment. When the base film has a surface smoothing layer on the surface on which the release agent is applied, the upper surface treatment is performed with respect to the surface smoothing layer.

<The release agent is applied to the substrate film>

The release film of the release film-attached double-sided adhesive tape of the present invention has a release layer obtained by applying a release agent on one side surface of the base film as described above.

The release agent to be applied to the base film is not particularly limited, and examples thereof include a conventional release agent such as a fluorene-based, fluorine-based or long-chain alkyl group. In the present invention, the stability from the peeling force and the adhesion to the base film are preferably lanthanum strippers.

The above-mentioned oxime-based release agent can be exemplified by a thermosetting type ruthenium using a platinum catalyst, an ultraviolet-curable ruthenium type using a UV-excited cation generator as a catalyst, and the like.

A thermosetting type ruthenium using a platinum catalyst is an alkyl siloxane having at least one carbon-carbon double bond; an alkyl siloxane having at least one oxime-hydrogen bond; and a platinum catalyst . As the above-mentioned thermosetting type crucible, an additional type which is generally sold can be used.

On the other hand, as the ultraviolet curable fluorene, a compound obtained by substituting a benzene nucleus having an epoxy benzene with an alkyl siloxane and a mixture of a UV-excited cation generating catalyst can be used, and a generally widely sold product can be used. As an ultraviolet curing type.

In the release film of the present invention, in the double-sided adhesive tape, the peeling force of the release film of the double-sided adhesive tape is preferably different from that of the front and back. When the peeling film is peeled off and the peeling film is peeled off, the double-sided adhesive tape does not adhere to the peeling film on the different sides of each region when the peeling film is bonded to the double-sided adhesive tape of the present invention. It is preferable to destroy the adhesive layer so that the entire double-sided adhesive tape remains on the release film on the side having a strong peeling force.

The difference in peeling force of the back of the watch is preferably 2 times or more, more preferably 3 times or more. In particular, the peeling force on the side having a large peeling force is preferably 30 to 500 (mN/25 mm), and more preferably 50 to 300 (mN/25 mm). The peeling force of one side with a small peeling force is preferably 10 to 300 (mN/25 mm), and more preferably 20 to 100 (mN/25 mm), and the difference between the peeling forces of both sides is preferably 2 times or more. More than 3 times better.

The peeling force can be adjusted by using a release agent applied to the single base film together with the use of the peeling force adjuster. The surface of the release agent after the application of the peeling force adjusting agent "strengthens" the peeling property, that is, forms a surface which makes peeling of the double-sided adhesive tape more difficult.

The peeling force adjusting agent usable herein may, for example, have SiO ₂ units in the alkyl siloxane, and (CH ₃ ) ₃ SiO _2/1 unit or CH ₂ =CH(CH ₃ ) ₂ SiO _2/1 unit. Resin structure, etc. The commercially available product of the above-mentioned peeling force modifier may, for example, be KS-3800 (manufactured by Shin-Etsu Chemical Co., Ltd.).

The blending force adjusting agent is preferably used in an amount of from 1 to 40 parts by weight, more preferably from 5 to 30 parts by weight, based on 100 parts by weight of the release agent.

Further, the release agent or the mixture of the release agent and the release force adjuster described above is in a state of being or diluted with a solvent and applied to the surface of the base film. Next, when the release agent is a thermosetting type crucible, by heating, in the case of an ultraviolet curing type crucible, the release agent is cured by irradiation of ultraviolet rays, whereby a release agent layer can be formed on the base film.

The smear method is not particularly limited, and a conventional method can be used. For example, a coating method by a coating head generally used can be appropriately selected; for example, a transfer method using a gravure, a gravure, a bias, or the like as a basic coating method; and a mold of a mold coater is extruded at a predetermined thickness. A method of laminating after coating a film; a method of squeezing a squeegee or a comma squeegee as a basic smear method, and the like is generally applied.

The conditions of heating or ultraviolet irradiation can be appropriately set by the type of the release agent to be used and the thickness of the release layer.

The thickness of the release agent is not particularly limited, and can be appropriately set in accordance with the peeling force for the release film. The thickness is, for example, 0.01 to 0.5 μm, and the stability of the peeling force is preferably 0.05 to 0.2 μm for the amount of transfer of the back surface.

<Ultraviolet curing adhesive>

The double-sided adhesive tape of the release film-attached double-sided adhesive tape of the present invention is formed of a cured product of an ultraviolet-curable adhesive.

The ultraviolet curable adhesive may, for example, be a UV-curable adhesive of a rubber-based adhesive such as a styrene-butadiene copolymer emulsion or a styrene-isoprene copolymer; or an ultraviolet curable type of an acrylic adhesive; An ultraviolet curing type of an adhesive such as a lanthanum.

These ultraviolet curable adhesives are provided, for example, in the form of a solvent system, an aqueous emulsion system, a hot melt system or the like. When the thickness of the adhesive layer is, for example, 50 μm or more, and particularly 80 μm or more, although a hot-melt adhesive is used, a thick layer can be formed in one step. ideal.

<Method for Producing Release Film-Coated Double-Sided Adhesive Tape>

The release film of the present invention has a double-sided adhesive tape which has a first release film having a release layer on a base film formed of a polyolefin resin, a UV-curable adhesive, and a base film formed of a resin. The second release film of the release layer is laminated in this order as a laminate, and the laminate can be produced by at least the ultraviolet irradiation step of irradiating ultraviolet rays from the side of the first release film. The two release films are disposed such that the surface having the release layer is bonded to the adhesive layer. It is preferable that the two release films are provided with different peeling forces as described above, but the peeling force of any one of the release films can be improved. When the curing reaction of the adhesive is performed on the release film by ultraviolet irradiation, the actual peeling force tends to be higher than the original peeling force of the release film. In such a case, the difference in peeling force between the two faces becomes small. In order to avoid this, the first release film is preferably a release film having a high peeling force. The base film of the second release film is preferably a polyolefin resin composition as described above.

The thickness of the ultraviolet curable adhesive can be appropriately set in accordance with the use of the release film of the present invention to bond the double-sided adhesive tape. In order to maximize the advantage that the release film having the base film of the polyolefin resin does not absorb the ultraviolet light of a specific wavelength, the thickness of the ultraviolet-curable adhesive is preferably 20 μm or more, more preferably 50 to 500 μm, and 80~300μm is the best.

According to the first release film, the ultraviolet curing adhesive, and the second release film In the method of laminating the laminates, for example, a layered ultraviolet curable adhesive is applied to the release layer forming surface of one of the first release film and the second release film, and then the other release film laminate is laminated. A method of bonding a release layer to the layer of the above ultraviolet curable adhesive.

The method of applying the ultraviolet curable adhesive layer to the release film in a layered form is not particularly limited, and a conventional method can be appropriately selected and used. The smear method can be, for example, a smear method using a coating head which is generally used; for example, a smear method based on a transfer method such as gravure, gravure, offset, etc.; a mold of a mold coater having a predetermined thickness A method of laminating a film after extrusion; a method of picking with a doctor blade or a comma blade is a general application method such as a basic application method.

The layer of the UV curable adhesive that cures to form the double-sided adhesive tape may or may not have a film-like substrate in the layer. However, in consideration of the simplification of the manufacturing steps and the maintenance of the optical characteristics of the double-sided adhesive tape, it is preferred that the film-form substrate is not provided.

Further, in the laminate, the release film-bonding double-sided adhesive tape of the present invention can be obtained at least through the ultraviolet irradiation step of irradiating ultraviolet rays from the first release film side.

When the base film of the second release film is composed of a polyolefin resin, the irradiation of the ultraviolet rays in the ultraviolet irradiation step may be performed not only from the first release film side but also from both surfaces. Therefore, according to this state, the irradiation time of the ultraviolet rays can be shortened, and the step time can be further shortened.

The conditions of the ultraviolet irradiation described above can be appropriately set depending on the type and thickness of the ultraviolet curable adhesive to be used.

Hereinafter, a preferred method of producing the release film-bonding double-sided adhesive tape of the present invention will be described with reference to the drawings.

Fig. 1 and Fig. 2 are schematic diagrams showing an example of a manufacturing apparatus preferably used in the method of the present invention.

The apparatus of the first embodiment has a film supply device that supplies a first release film (a release film having a release layer having a strong peeling force), and a film delivery device that supplies a second release film (a release film having a release layer having a weak release force). a device; a mold for supplying an ultraviolet curable adhesive; a cooling roller for cooling an adhesive supplied to the release film; an ultraviolet irradiation device for irradiating ultraviolet rays from both surfaces of the laminate; a winding roller and a plurality of support rollers. The base film of the release film used herein is composed of a polyolefin resin, and the ultraviolet curable adhesive is a hot melt type.

A release film having a release layer having a strong peeling force sent from a film feeding device that supplies the first release film is guided onto a cooling roll, and an ultraviolet curable adhesive supplied from the mold is laminated on the release layer. Since the temperature of the mold is set to a temperature at which the ultraviolet curable adhesive has sufficient fluidity, the mold is supplied in a state in which the adhesive has fluidity. The adhesive is subsequently cooled or lost by the cooling roller through the release film, and at the same time or subsequently, on the adhesive layer, the laminate is supplied from the film delivery device that supplies the second release film. The release film of the peeling layer of weak peeling force forms a laminated body. Here, the release film from the film feeding device that supplies the second release film is supplied by bonding the release layer having the release film to the pressure-sensitive adhesive layer.

The obtained laminate was irradiated with ultraviolet rays from both surfaces, and the ultraviolet curable adhesive was cured and wound around a winding roller.

The apparatus of Fig. 2 is a device in which the adhesive is replaced by a Meyer bar smearing method using a Meyer bar in the apparatus of Fig. 1 instead of the mold. The details of the other aspects of the apparatus of Figure 2 should be readily understood by the practitioner.

As described above, the release film supplied from the film discharge device that supplies the first release film and the release film supplied from the film discharge device that supplies the second release film can be replaced with each other. Further, ultraviolet irradiation may be performed from only one of them.

As described above, in the method of the present invention, ultraviolet irradiation is performed in a state in which both surfaces of the ultraviolet curable adhesive layer are protected by a release film. According to this state, the time for exposing one side of the ultraviolet curable adhesive layer to the environment at the manufacturing site can be extremely shortened, so that it is extremely possible to reduce the adhesion of foreign matter such as dust in the environment to the adhesive layer as much as possible. ideal.

This has a great advantage in the case of a conventional method using a substrate film in which PET is a release film. That is, according to the conventional method, since the PET constituting the base film absorbs ultraviolet rays, it is necessary to perform ultraviolet irradiation in a state where one side of the adhesive layer is exposed to the environment of the manufacturing site in order to avoid this. Therefore, the conventional method does not eliminate the dust adhered to the adhesive layer even if the dust-free manufacturing site is formed within the usual cost tolerance of the film industry. The above-described concerns of the conventional method can be fundamentally solved by the method of the present invention.

<Release film bonding double-sided adhesive tape>

The release film of the present invention obtained as described above is bonded to the double-sided adhesive tape, and it is revealed that even if the thickness of the adhesive layer is thick, it is not caused by ultraviolet irradiation. Good adhesion properties that hinder the curing reaction.

The release film-attached double-sided adhesive tape of the present invention is particularly suitable for use in optical applications.

[Examples]

The following examples and comparative examples are intended to describe the present invention, but the present invention is not limited to the examples.

The evaluations of the following examples and comparative examples were carried out by the following procedures.

(1) Tensile modulus of elasticity

The tensile elastic modulus was measured by the index of the rigidity of the base film of the release film.

The measuring device was manufactured by Shimadzu Corporation, AUTOGRAPH (model number: AG-500D), based on JIS K 7127, using JIS-5 test piece at a tensile speed of 50 mm/min, for MD direction and TD. The directions are measured separately.

(2) Peel force

The No. 31B tape manufactured by Nitto Denko Co., Ltd. was pressure-bonded to the peeling surface of the release film with a roller of 5 kg, and the state was adjusted at 23 ° C for 24 hours, and then the tape was peeled off by 180° at a speed of 300 mm/min. Thereby, the peeling force was measured.

(3) turbidity

The turbidity was measured by adhering the peeling film to the index of the transparency of the double-sided adhesive tape.

The measurement apparatus was measured using a SUGA tester (manufactured by the company) and HAZE-METER (model number: HGM-2DP) based on JIS K 7105.

(4) Fish eyes and foreign bodies

The presence or absence of fish eyes and foreign matter present in the double-sided adhesive tape attached to the release film was visually observed. For the fish eyes and foreign matter found, the long diameter was measured with a magnifying glass with a minimum unit of 0.1 mm, and the number of sizes of 0.2 mm or more was converted into the number per 1 m ² .

(5) Curing condition of the adhesive

The peeling film of the double-sided adhesive tape was peeled off from the peeling mold, and the corona-treated side of the PET film (E5100 #50: manufactured by Toyobo Co., Ltd.) was attached to the adhesive surface to make a thin 25 mm wide by 150 mm. Rectangular test piece. Then, the release film of the test piece was peeled off, and the test piece was peeled off after being attached to the SUS plate. The condition of the adhesive layer at this time was visually confirmed.

Yes: No adhesive layer is destroyed, and all adhesives remain on the PET film side.

No: The adhesion between the adhesive layer and the PET film was low, the adhesive layer was damaged, and the adhesive remained on both the PET film and the SUS plate.

(6) Peeling condition

The residual state of the adhesive layer when the release film of the peeling film was bonded to the peeling film of the double-sided adhesive tape (the side having a small peeling force when the peeling force is small) was visually observed.

Yes: There is no damage to the adhesive layer, and all the adhesives remain on one side (both sides have a peeling force when the peeling force is poor).

No: The adhesive layer was damaged, and peeling films on different sides remained in each region.

(Example 1) (manufacture of release film)

A release film was produced by the following method using a non-stretched polypropylene film PP-1 (SUN.TOX (product number: R012 #60, thickness: 60 μm) as a base film.

On the corona-treated side of the base film, a heat-curable 矽-1 (manufactured by Shin-Etsu Chemical Co., Ltd., product number: KS-3703) and a peeling force adjuster (Shin-Etsu) were applied by a gravure roll coater. Chemical Industry Co., Ltd., product number: KS-3800) A mixture of 20 parts by weight, and the amount of application was 0.1 g/m ² to obtain a first release film.

Different from the above, on the corona-treated side of the base film, a heat-curable 矽-2 (manufactured by Dongling.Dow-Corning Co., Ltd., product number: LTC750A) was applied by a gravure roll coater to form an application amount. 0.1 g/m ² , a second release film was obtained.

The evaluation of the above (1) and (2) was carried out using these release films. The results of the evaluation are shown in Table 1.

(Release film bonding double-sided adhesive tape manufacturing)

The production of the release film-bonded double-sided adhesive tape was carried out using the manufacturing apparatus shown in Fig. 1. Here, the temperature of the mold for supplying the ultraviolet curable adhesive is 120 ° C, the temperature of the cooling water of the cooling roll is 5 ° C, the winding speed of the belt is 4 m / s, and the amount of ultraviolet rays irradiated is adjusted to make the following (the Both the peeling film side and the upper surface (the second peeling film side) formed 600 J/m ² .

The first release film obtained above was supplied from the delivery device, and guided to a cooling roll, and the ultraviolet curable adhesive HM-1 (manufactured by No-tape Industrial Co., Ltd.) was supplied from the mold on the cooling roll. UV300) was applied to the release layer of the first release film and applied to a thickness of 175 μm. Subsequently, the second release film obtained as described above is supplied from the delivery device to the laminate on the adhesive layer.

Next, ultraviolet rays were irradiated from both surfaces to the obtained laminate, and the ultraviolet curable adhesive was cured, and then wound around a winding roller, whereby a release film-bonded double-sided adhesive tape was obtained.

The above-mentioned (3) to (6) were evaluated by adhering the double-sided adhesive tape to the obtained release film. The results of the evaluation are shown in Table 1.

(Example 2)

A release film-bonded double-sided adhesive tape was obtained in the same manner as in Example 1 except that the thickness of the UV-curable adhesive HM-1 applied was 50 μm. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The evaluation results are shown in Table 1. Further, in the present embodiment, since the same release film material as in the above-described first embodiment was used, the evaluations of the above (1) and (2) were reproduced by the evaluation results of the first embodiment.

(Example 3)

A release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the ultraviolet rays were irradiated from the second release film side (upper side). The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The evaluation results are shown in Table 1. Further, in the present embodiment, since the same release film material as in the above-described first embodiment was used, the evaluations of the above (1) and (2) were reproduced by the evaluation results of the first embodiment.

(Example 4)

The production of the release film-bonding double-sided adhesive tape was carried out using a manufacturing apparatus as shown in Fig. 2 . Here, the application of the ultraviolet curable adhesive is carried out without heating the adhesive, the winding speed of the sheet is 4 m/s, and the amount of ultraviolet light to be irradiated is the upper side (the first peeling film side) and the lower side ( The second release film side) was also adjusted to 600 J/m ² .

In addition, NS-1 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product number: NS-001) was used as the ultraviolet curable adhesive, and the thickness of the adhesive was 50 μm except that the Meyer bar was used for Mayer smearing. The above Example 1 was similarly applied to obtain a release film-bonded double-sided adhesive tape.

The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The evaluation results are shown in Table 1. Further, in the present embodiment, since the same release film material as in the above-described first embodiment was used, the evaluations of the above (1) and (2) were reproduced by the evaluation results of the first embodiment.

(Example 5) (manufacture of release film)

It consists of three types of three layers of a single-axis extruder (for the intermediate layer) with a screw diameter of 75 mm and two single-axis extruders (two outer layers) with a screw diameter of 50 mm. The T-die film forming apparatus performs the production of the base film used for the first release film.

The polyethylene resin PE (made by Ube Maruzen Polyethylene Co., Ltd., product number: F522N, density=0.922g/cm ³ , melting point = 110 ° C, MFR = 5.0 g/10 min; 190 ° C) is used as the intermediate layer and The resin of the two outer layers of the extruder was extruded at a resin temperature of 250 ° C, a residence time of 1 minute, and a T-die temperature of 240 ° C, and passed through a 25 ° C cooling roll to obtain a polyethylene film having a total thickness of 60 μm. Next, a wetting discharge treatment was carried out to form a wetting index of the surface of the adhesive-side layer on which the film was laminated to 42 mN/m, and the substrate was obtained by anti-aging at 40 ° C for 24 hours.

The first release film was obtained in the same manner as in Example 1 except that the base film was used.

The second release film was produced by using PP-1 as a base film in the same manner as in the above Example 1.

The evaluation of the above (1) and (2) was carried out using these release films. The results of the evaluation are shown in Table 1.

(Release film bonding double-sided adhesive tape manufacturing)

A release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the first and second release films produced as described above were used. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. Evaluation The results are shown in Table 1.

(Example 6)

A release film was obtained in the same manner as in Example 1 except that a PET film (manufactured by Toyobo Co., Ltd., product number: E5100) was used as the base film used for the first release film. The evaluation of the above (1) and (2) was carried out using the release film. The results of the evaluation are shown in Table 1.

Then, a release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the first and second release films were used. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The results of the evaluation are shown in Table 1.

(Example 7)

A non-stretched polypropylene film PP-2 (manufactured by SUN. TOX, product number: MK12 #40, thickness: 40 μm) was used in the same manner as in the above-described Example 1 except that the base film used for the first release film was used. A release film was obtained. The evaluation of the above (1) and (2) was carried out using the release film. The results of the evaluation are shown in Table 1.

Then, a release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the release film was used. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The results of the evaluation are shown in Table 1.

(Example 8) (manufacture of release film)

Using the same apparatus as in Example 5, the first release film was used. Manufacture of substrate film.

100 g portions of homopolypropylene PP-3 (manufactured by Sumitomo Chemical Co., Ltd., product number: FLX80E4, melting point = 163 ° C, MFR = 7 g/10 min; 230 ° C) as an extruder for supplying the intermediate layer and the two outer layers The resin is mixed with 5 parts by weight of the masterbatch masterbatch (made by DIC), product number: PEONY HP BLUE L-83285M, base resin = 100 parts by weight of the resin of the extruder supplying the intermediate layer. A base film was obtained in the same manner as in the above Example 5 except that the polypropylene and the pigment concentration were about 5%.

A first release film was obtained in the same manner as in Example 1 except that the base film was used.

The second release film was produced by using PP-1 as a base film in the same manner as in the above Example 1.

The evaluation of the above (1) and (2) was carried out using these release films. The results of the evaluation are shown in Table 1.

(Release film bonding double-sided adhesive tape manufacturing)

A release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the first and second release films produced as described above were used. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The results of the evaluation are shown in Table 1.

(Comparative Example 1)

The base film used for the first and second release films is the same as the above-described first embodiment except that the PET film (made by Toyobo Co., Ltd., product number: E5100) The release film was obtained by the sample. The evaluation of the above (1) and (2) was carried out using the release film. The results of the evaluation are shown in Table 1.

Then, a release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the release film was used. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The results of the evaluation are shown in Table 1.

(Comparative Example 2)

A release film was obtained in the same manner as in the above Example 2 except that the base film used for the first and second release films was a PET film (manufactured by Toyobo Co., Ltd., product number: E5100). The evaluation of the above (1) and (2) was carried out using the release film. The results of the evaluation are shown in Table 1. Then, a release film-bonding double-sided adhesive tape was obtained in the same manner as in Example 1 except that the release film was used. The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The results of the evaluation are shown in Table 1.

(Reference example 1)

In the above-mentioned Comparative Example 1, the double-sided adhesive tape was bonded to the release film which was wound on the winding roller by one-time irradiation with ultraviolet rays, and the second ultraviolet irradiation was further performed as follows.

The double-sided adhesive tape is bonded to the release film from the roll, and the second release film is peeled off from the both sides of the sheet after the second release film is peeled off. Then, a new second release film is bonded and wound into a laminate.

The peeling of the second release film and the operation of ultraviolet irradiation were repeated once more, whereby a release film-bonded double-sided adhesive tape was obtained.

The double-sided adhesive tape was bonded to the release film, and the evaluation of the above (3) to (6) was performed. The evaluation results are shown in Table 1. Further, in the present embodiment, since the same release film material as in Comparative Example 1 was used, the evaluations of the above (1) and (2) were reproduced by the evaluation results of Comparative Example 1.

[effect of the invention]

When the peeling film of the present invention is bonded to the double-sided adhesive tape, even if the thickness of the adhesive layer is thick, it is not hindered by the curing reaction by ultraviolet irradiation, and good adhesive properties can be exhibited. Therefore, the release film-attached double-sided adhesive tape of the present invention is particularly useful for optical applications.

The method for producing a release film of the present invention in which a double-sided adhesive tape is bonded can be produced by a simple method, and the above-mentioned excellent release film-bonding double-sided adhesive tape can be produced. In particular, even when the thickness of the adhesive layer is thick, the adhesive layer of the adhesive layer which does not require a plurality of ultraviolet rays can be cured, and the release film can be easily bonded to the double-sided adhesive tape with excellent performance.

Fig. 1 is a schematic view showing an example of a preferred production apparatus for producing a double-sided pressure-sensitive adhesive tape for use in a release film of the present invention.

Fig. 2 is a schematic view showing another example of a preferred manufacturing apparatus for producing a double-sided pressure-sensitive adhesive tape for use in a release film of the present invention.

Claims (6)

A release film-bonding double-sided adhesive tape, which is characterized in that a double-sided adhesive tape composed of a single layer of a cured product of an ultraviolet-curable adhesive is bonded to a double-sided adhesive tape, and the release film is formed of a resin. The surface of the base film on the bonding surface side has a release layer, and the resin constituting at least one of the release films bonded to both surfaces of the double-sided adhesive tape is a polyolefin resin. A release film-bonding double-sided adhesive tape according to the first aspect of the invention, wherein the polyolefin resin constituting the base film is a polypropylene resin. A release film-bonding double-sided adhesive tape according to the second aspect of the invention, wherein the base film formed of the polypropylene resin is a non-stretch polypropylene film. The release film-bonding double-sided adhesive tape according to the first aspect of the invention, wherein the resin constituting the release film is a polyolefin resin. A method for producing a release film-bonding double-sided adhesive tape, which is a method for producing a release film-bonding double-sided adhesive tape according to claim 1, which is characterized in that: a base film composed of a polyolefin resin a first release film having a release layer; a single-layer ultraviolet-curable adhesive; and a second release film having a release layer on a base film formed of a resin The steps of laminating into a laminate and irradiating ultraviolet rays on at least the first release film side with respect to the laminate are performed. The method for producing a release film-bonding double-sided adhesive tape according to the fifth aspect of the invention, wherein the resin constituting the base film of the second release film is a polyolefin resin, and ultraviolet rays are irradiated from both surfaces of the laminate. The step of ultraviolet light irradiation.