JP2024025746A - Adhesive composition for patterned adhesive tape, patterned adhesive tape and manufacturing method thereof - Google Patents

Abstract

[Problem] The problem to be solved by the present invention is to provide a thin patterned adhesive that can quickly release air bubbles from the interface with an adherend, prevent air bubbles from remaining at the interface, and has excellent adhesive strength. An object of the present invention is to provide a tape and an adhesive composition for a patterned adhesive tape. The pressure-sensitive adhesive composition for patterned pressure-sensitive adhesive tapes of the present invention has a Trouton ratio of 8 to 400 when measured at 30°C. The patterned adhesive tape has an adhesive layer. The adhesive layer has two or more adhesive parts (B) and a non-adhesive region having no adhesive part (B) between the two or more adhesive parts (B), and the non-adhesive region is It has a pattern that extends to the outer periphery of the sheet plane. [Selection diagram] Figure 1

Description

The present invention relates to a pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape, a patterned pressure-sensitive adhesive tape, and a method for producing the same.

Adhesive tapes have excellent workability and high adhesion reliability, and are therefore widely used, for example, in the production of electronic devices such as office automation equipment and home appliances.

In recent years, there has been a demand for higher functionality, smaller size, and thinner electronic devices for the electronic devices mentioned above, especially for portable electronic devices such as personal computers, digital video cameras, electronic notebooks, mobile phones, PHS, smartphones, game devices, and e-books. Devices are required to be even smaller and thinner. Accordingly, adhesive tapes and the like constituting the portable electronic terminals are also required to be made thinner.

The thin adhesive tape is, for example, mainly composed of an acrylic ester copolymer having a weight average molecular weight of 700,000 or more and a content of butyl acrylate units of 90% by mass or more, and a tackifier, and A double-sided adhesive tape having adhesive layers containing 40 to 60% by mass of the tackifier on both sides of the core material, the total thickness of the core material and the adhesive layers on both sides being 30 μm. A double-sided adhesive tape is known in which the thickness of the adhesive layer on both sides is 2 to 10 μm (for example, see Patent Document 1).

However, when the thin adhesive tape is bonded to an adherend, air bubbles tend to remain at the interface thereof, which may result in poor appearance due to swelling of the adhesive tape or the like.

Moreover, since the remaining air bubbles act as thermal resistance, when the thin adhesive tape is used to bond a heat-radiating member to a heat-generating member, etc., heat dissipation performance may be lowered.

In addition, while consideration is being given to reducing the thickness of the adhesive layer in order to achieve the above-mentioned thinness, it has been found that an adhesive layer that is thin and simply provides an escape route for the air bubbles can maintain sufficient adhesion force for practical use. There were times when it was not possible to do so.

Japanese Patent Application Publication No. 2007-169327

The problem to be solved by the present invention is to provide a patterned adhesive tape that can quickly release air bubbles from the interface with an adherend, prevent air bubbles from remaining at the interface, and has excellent adhesive strength. It is.

The content of this disclosure includes the following embodiments.
[1] A pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape, which is used for forming a patterned pressure-sensitive adhesive tape,
The pressure-sensitive adhesive composition for patterned pressure-sensitive adhesive tape has a Trouton ratio of 8 or more and 400 or less when measured at 30°C,
The patterned adhesive tape has an adhesive layer,
The adhesive layer has two or more adhesive portions (B) and a non-adhesive region having no adhesive portion (B) between the two or more adhesive portions (B),
A pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape, wherein the non-adhesive region has a pattern extending to the outer periphery of a flat sheet.
[2] Includes a support (A) and an adhesive layer,
The adhesive layer is formed using the adhesive composition for patterned adhesive tape according to [1],
The adhesive layer has two or more adhesive portions (B) and a non-adhesive region having no adhesive portion (B) between the two or more adhesive portions (B),
A patterned adhesive tape, wherein the non-adhesive region has a pattern that extends to the outer periphery of the sheet plane.
[3] The shape of the adhesive portion (B) when observed from one surface (a) side of the support (A) is approximately circular, approximately square, or approximately hexagonal. The patterned adhesive tape according to [2].
[4] The distance between any adhesive part (b1) selected from the two or more adhesive parts (B) and the adhesive part (b2) adjacent to the adhesive part (b1) is 0.5 mm or less [ 2] or the patterned adhesive tape according to [3].
[5] Any one of [2] to [4], wherein the area having the adhesive portion (B) occupies 10% to 99% of the area of one side (a) of the support (A). Patterned adhesive tape described in .
[6] A smooth stainless steel plate was placed on the surface having the adhesive part (B), and a 2 kg roller was used to make one reciprocation to press them together, and the plate was left for 1 hour at 23° C. and 50% RH. The patterned adhesive tape according to any one of [2] to [5], which has a 180° peel adhesive strength in the range of 2 N/20 mm to 12 N/20 mm, as measured using a test piece obtained by the method.
[7] A pressure-sensitive adhesive layer forming step of forming a pressure-sensitive adhesive layer on the surface of the support (A) using the pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape according to [1],
A method for producing a patterned adhesive tape, wherein the adhesive layer has two or more adhesive parts and a non-adhesive region having no adhesive part (B) between the two or more adhesive parts (B).
[8] In the adhesive layer forming step, by applying the adhesive composition for patterned adhesive tape on at least one surface of the support (A) by a gravure printing method or a screen printing method, approximately The method for producing a patterned adhesive tape according to [7], wherein two or more adhesive portions (B) are formed in a circular shape, a substantially square shape, or a substantially hexagonal shape.

The patterned pressure-sensitive adhesive tape of the present invention allows air bubbles to escape quickly from the interface with the adherend, making it difficult for air bubbles to remain at the interface, and having excellent adhesive strength.

FIG. 2 is a top view of a patterned adhesive tape having a substantially diamond-shaped adhesive portion, viewed from the adhesive portion side. FIG. 2 is a top view of a patterned adhesive tape having a substantially circular adhesive portion, viewed from the adhesive portion side. FIG. 2 is a top view of a patterned adhesive tape having a substantially hexagonal adhesive portion, viewed from the adhesive portion side. FIG. 2 is a top view of a patterned adhesive tape having a substantially line-shaped adhesive portion, viewed from the adhesive portion side. FIG. 2 is a side view of a graphite composite sheet.

(Adhesive composition for patterned adhesive tape)
The pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape of one embodiment of the present invention (sometimes referred to as the pressure-sensitive adhesive composition of this embodiment) is used for forming a patterned pressure-sensitive adhesive tape described below. The Truton ratio of the adhesive composition of this embodiment when measured at 30° C. is 8 or more and 400 or less. The patterned adhesive tape has an adhesive layer, and the adhesive layer has two or more adhesive parts (B) and no adhesive part (B) between the two or more adhesive parts (B). The sheet has a non-adhesive region, and the non-adhesive region has a pattern that extends to the outer periphery of the sheet plane.

In the patterned adhesive tape, air bubbles quickly escape from the interface with the adherend, making it difficult for air bubbles to remain at the interface. It is required that it not be blocked due to deformation, etc. On the other hand, in order for the patterned adhesive tape to exhibit excellent adhesive strength, it is required that the adhesive part be formed with stable dimensions and that a sufficient adhesive area can be obtained from the adhesive part.
The adhesive composition of this embodiment has a Trouton ratio within a predetermined range when measured at 30°C, thereby preventing the non-adhesive region from being blocked by the adhesive composition during the formation of the adhesive part. be able to. Further, it is possible to form an adhesive portion with good shape accuracy and shape retention. Thereby, the patterned pressure-sensitive adhesive tape formed using the pressure-sensitive adhesive composition of the present embodiment can achieve both good air bubble removal and good adhesive strength.

The Trouton ratio of the adhesive composition of the present embodiment when measured at 30° C. is preferably 8 or more and 400 or less, more preferably 25 or more and 375 or less, and still more preferably 100 or more and 350 or less. preferable.
When forming a patterned adhesive tape, by using the adhesive composition of this embodiment having a Trouton ratio of 8 or more when measured at 30°C, an adhesive part with good shape accuracy and shape retention can be formed. can be formed. In particular, when forming an adhesive part using various printing methods, the adhesive composition is excellent in transferability from a printing plate and in shape retention of the adhesive part after transfer. By using the adhesive composition of this embodiment having a Trouton ratio of 400 or less when measured at 30°C when forming a patterned adhesive tape, it is possible to apply the adhesive composition regardless of the type of printing method. First, it is possible to easily form an adhesive portion with good shape accuracy. In particular, when forming an adhesive part using a printing plate, it is possible to easily form an adhesive part with a small error in the shape and size of the adhesive part transferred and formed by the dots with respect to the shape and size of the dots on the plate.

In addition, in the method of manufacturing a patterned adhesive tape described below, when the method of applying the adhesive composition of the present embodiment is a gravure printing method, the Trouton ratio when measured at 30 ° C. is 8 or more and 400 or less. It is preferably 8 or more and 333 or less, more preferably 8 or more and 144 or less, and even more preferably 9.3 or more and 100 or less.
By setting the Trouton ratio of the adhesive composition used in the gravure printing method within the above range, the adhesive composition can easily flow out from the concave part of the gravure plate corresponding to the adhesive part, and the adhesive composition can be applied to the support or release liner. Things can be transferred easily. In addition, the shape retention and dimensional accuracy of the adhesive portion after transfer are excellent.

In the method for producing a patterned adhesive tape described below, when the method of applying the adhesive composition of this embodiment is a screen printing method, the Trouton ratio when measured at 30 ° C. should be 8 or more and 400 or less. It is preferably 160 or more and 400 or less, more preferably 200 or more and 400 or less, and even more preferably 250 or more and 400 or less.
By setting the Trouton ratio of the adhesive composition used in the screen printing method within the above range, the adhesive composition can be held in the holes of the screen plate corresponding to the adhesive part, and during transfer, the adhesive composition can be transferred from the holes. The pressure-sensitive adhesive composition can be easily transferred to the support or release liner. In addition, the shape retention and dimensional accuracy of the adhesive portion after transfer are excellent.

Examples of the adhesive composition of this embodiment include an acrylic adhesive composition, a rubber adhesive composition, a silicone adhesive composition, a urethane adhesive composition, a polyester adhesive composition, and a styrene-diene adhesive composition. Block copolymer-based adhesive composition, vinyl alkyl ether-based adhesive composition, polyamide-based adhesive composition, fluorine-based adhesive composition, creep property-improved adhesive composition, radiation-curable adhesive composition Examples of known pressure-sensitive adhesive compositions include: Among them, the pressure-sensitive adhesive composition of this embodiment is preferably an acrylic pressure-sensitive adhesive composition because a patterned pressure-sensitive adhesive tape formed using an acrylic pressure-sensitive adhesive composition has excellent adhesion reliability.

[Acrylic adhesive composition]
As the acrylic adhesive composition, one containing an acrylic polymer can be used.

<Acrylic polymer>
As the acrylic polymer, one obtained by polymerizing a monomer component containing a (meth)acrylic monomer such as a (meth)acrylic acid alkyl ester can be used.

Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylate. ) Isobutyl acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate , octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, (meth)acrylic acid Isodecyl, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate , octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. can be used alone or in combination of two or more. Among these, as the (meth)acrylic acid alkyl ester, it is preferable to use a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms, and in which the alkyl group has 4 to 18 carbon atoms. It is more preferable to use (meth)acrylic acid alkyl esters. Examples of the alkyl group include linear or branched alkyl groups.

As the (meth)acrylic acid alkyl ester in which the alkyl group has 4 to 18 carbon atoms, it is preferable to use butyl (meth)acrylate to maintain the surface shape of the adhesive layer (the surface shape of the adhesive part). It is preferable for obtaining a patterned adhesive tape that can easily prevent changes over time, can easily release air bubbles from the interface with the adherend (air release property), and can maintain good adhesive strength.

The content of the (meth)acrylic acid alkyl ester is preferably in the range of 80% to 98.5% by mass, and 90% to 98.5% by mass based on the total amount of monomers constituting the acrylic copolymer. % range is more preferable. Among these, it is preferable that the content of (meth)acrylic acid alkyl ester in which the alkyl group has 4 to 18 carbon atoms is within the above range. This is because the adhesive portion can maintain good adhesive strength.

In addition to the above-mentioned (meth)acrylic monomers, monomers having a carboxyl group such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, or their anhydrides; ; Monomers having a sulfonic acid group such as sodium vinyl sulfonate; Monomers having a cyano group such as acrylonitrile; Amide groups such as acrylamide, methacrylamide, N-vinylpyrrolidone, N,N-dimethyl (meth)acrylamide, etc. Monomers having a hydroxyl group such as hydroxyalkyl (meth)acrylate and glycerin dimethacrylate; Monomers having an amino group such as aminoethyl (meth)acrylate and (meth)acryloylmorpholine; Monomers with imide groups such as cyclohexylmaleimide and isopropylmaleimide; monomers with epoxy groups such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; monomers with isocyanate groups such as 2-methacryloyloxyethyl isocyanate. monomer with triethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6 - Use of monomers such as hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinylbenzene, etc. singly or in combination of two or more can do.

Among these, it is preferable that the acrylic polymer contains a monomer having a carboxyl group as a monomer component. The content of the monomer having a carboxyl group is preferably 0.2% by mass to 15% by mass, and 0.4% by mass to 10% by mass based on the total amount of monomers constituting the acrylic copolymer. More preferably, it is 0.5% by mass to 6% by mass. This is because when the content of the monomer having a carboxyl group is within the above range, when the adhesive part is formed, the adhesive part can exhibit suitable cohesive force, and the adhesiveness becomes good.

Moreover, it is preferable that the acrylic polymer contains a monomer having a hydroxyl group as a monomer component. The content of the monomer having a hydroxyl group is preferably 0.01% by mass to 1.0% by mass, and 0.03% by mass to 0.3% by mass based on the total amount of monomers constituting the acrylic copolymer. More preferably, it is expressed in mass %. When the content of the monomer having a hydroxyl group is within the above range, the adhesive part formed by the adhesive composition can exhibit good adhesive properties, and furthermore, the adhesive composition can be coated with the adhesive composition. The viscosity can be improved without impairing the properties and printability.

In addition to the (meth)acrylic monomer, the monomers include aromatic vinyl compounds such as styrene and substituted styrene; olefins such as ethylene, propylene, and butadiene; vinyl esters such as vinyl acetate; Vinyl chloride and the like can also be used.

The acrylic polymer can be produced by polymerizing the monomers by a method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, etc., and a solution polymerization method can be used. , is preferable for improving the production efficiency of acrylic polymers.

Examples of the solution polymerization method include a method in which the monomer, a polymerization initiator, and an organic solvent are mixed and stirred preferably at a temperature of 40° C. to 90° C., and radical polymerization is performed.

Examples of the polymerization initiator include peroxides such as benzoyl peroxide and lauryl peroxide, azo thermal polymerization initiators such as azobisisobutylnitrile, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, and benzyl. A ketal-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, etc. can be used.

The acrylic polymer obtained by the above method may be dissolved or dispersed in an organic solvent, for example, if it is produced by a solution polymerization method.

As the acrylic polymer obtained by the above method, it is preferable to use one having a weight average molecular weight of 300,000 to 1.2 million, more preferably one having a weight average molecular weight of 400,000 to 1.1 million. It is preferable to use a material having a weight average molecular weight of 500,000 to 1,000,000 in order to obtain a patterned adhesive tape with even better adhesive strength and ease of bubble removal even if it is thin. .

In addition, the said weight average molecular weight refers to the value measured by the gel permeation chromatography method (GPC method), and calculated by standard polystyrene conversion. Specifically, the weight average molecular weight can be measured using a GPC device (HLC-8329GPC) manufactured by Tosoh Corporation under the following conditions.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)
Sample injection volume: 100μl
Eluent: Tetrahydrofuran Flow rate: 1.0ml/min Measurement temperature: 40°C
Main column: TSKgel GMHHR-H (20) 2 Guard column: TSKgel HXL-H
Detector: Differential refractometer Weight average molecular weight of standard polystyrene: 10,000 to 20 million (manufactured by Tosoh Corporation)

The adhesive composition of this embodiment is one containing a tackifying resin in order to form an adhesive part (patterned adhesive layer) with even better adhesive strength, tensile strength, and tensile breaking strength. It is preferable to use

Examples of the tackifying resin include rosin-based tackifying resin, polymerized rosin-based tackifying resin, polymerized rosin ester-based tackifying resin, rosin phenol-based tackifying resin, stabilized rosin ester-based tackifying resin, and disproportionated rosin ester. Petroleum resin-based tackifier resins such as hydrogenated rosin ester-based tackifier resins, terpene-based tackifier resins, terpene-phenol-based tackifier resins, and styrene-based tackifier resins can be used.

As the tackifying resin, it is recommended to use a combination of a rosin-based tackifying resin and a petroleum resin-based tackifying resin to create a patterned shape that has even better adhesive strength and ease of bubble removal even if it is thin. Preferred for obtaining adhesive tapes. The rosin-based tackifier resin and petroleum resin-based tackifier resin are preferably used in combination with the acrylic polymer, and are preferably used in combination with the acrylic polymer obtained by polymerizing a monomer containing butyl (meth)acrylate. It is preferable to use them in combination in order to obtain a patterned adhesive tape that has even better adhesive strength and ease of bubble removal even if it is thin.

Further, as the tackifier resin, it is preferable to use a tackifier resin that is liquid at room temperature in order to further improve the initial adhesive strength of the adhesive part (B). Examples of tackifier resins that are liquid at room temperature include process oils, polyester plasticizers, and low molecular weight liquid rubbers such as polybutene.Terpene phenol resins can also be used, and commercially available products include YP manufactured by Yasuhara Chemical Co., Ltd. -90L etc.

The tackifier resin is preferably used in an amount of 20 parts by mass to 60 parts by mass, and even more preferably in an amount of 30 parts by mass to 55 parts by mass, based on 100 parts by mass of the acrylic polymer. This is more preferable in order to obtain a patterned adhesive tape with high adhesive strength.

In addition to the acrylic polymer, the adhesive composition constituting the adhesive part (B) may optionally contain a softener, plasticizer, filler, anti-aging agent, colorant, etc. You can use whatever you want.

Among these, the use of a crosslinking agent makes it possible to adjust the gel fraction of the adhesive part (B) to a suitable range, and as a result, the shape of the adhesive part (B) can be easily maintained, so that the gel fraction of the adhesive part (B) can be easily maintained over time. It is possible to obtain a patterned adhesive tape that can easily prevent chemical changes, can easily remove air bubbles from the interface between the adherend and the adhesive layer (B), and has excellent adhesive strength. Therefore, it is preferable.

As the crosslinking agent, it is preferable to use, for example, an isocyanate crosslinking agent or an epoxy crosslinking agent.

As the isocyanate crosslinking agent, for example, tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane-modified tolylene diisocyanate, etc. can be used, and tolylene diisocyanate, It is preferred to use toluene diisocyanate adducts such as trimethylolpropane-modified tolylene diisocyanate. The toluene diisocyanate adduct has a structure derived from toluene diisocyanate in its molecule, and examples of commercially available products include Coronate L (manufactured by Nippon Polyurethane Industries, Ltd.).

When using the isocyanate crosslinking agent, it is preferable to use an acrylic polymer having a hydroxyl group as the acrylic polymer. The acrylic polymer having a hydroxyl group may be produced using monomers such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, etc. It is more preferable to use 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate.

Furthermore, as the epoxy crosslinking agent, for example, Tetrad

When using the epoxy crosslinking agent, it is preferable to use an acrylic polymer having acid groups as the acrylic polymer. For example, (meth)acrylic acid, acrylic acid dimer, itaconic acid, crotonic acid, maleic acid, maleic anhydride, etc. are preferably used as monomers for producing the acrylic polymer having acid groups. , (meth)acrylic acid is more preferably used.

As the adhesive composition of this embodiment, it is preferable to use one containing a solvent as required. The adhesive composition may have a shear viscosity of 125 mPa·s to 1625 mPa·s, depending on the method of forming the adhesive part, and a shear viscosity of 400 mPa·s to 1200 mPa·s. It is preferable to use one adjusted within this range, and more preferably one adjusted within a range of 500 mPa·s to 1000 mPa·s because it is easier to form the adhesive portion (B) in a predetermined shape.
In the method of forming a patterned adhesive tape described below using the adhesive composition of the present embodiment, when the gravure printing method is used to form the adhesive part, the adhesive composition has a shear viscosity of It is possible to use one adjusted to a range of 125 mPa·s to 1500 mPa·s. It is preferable to use an adhesive prepared in the range of 125 mPa·s to 520 mPa·s, and it is preferable to use one prepared in the range of 140 mPa·s to 200 mPa·s. It is more preferable because it has good transferability and it is easy to form the adhesive part (B) in a predetermined shape.

In addition, in the method of forming a patterned adhesive tape described below using the adhesive composition of the present embodiment, when a screen printing method is used to form the adhesive part, the adhesive composition has a shear viscosity of is adjusted to a range of 500 mPa·s to 1625 mPa·s, preferably adjusted to a range of 1000 mPa·s to 1625 mPa·s, and 1200 mPa·s to 1625 mPa·s. It is more preferable to use one prepared within the range of s because the transferability of the adhesive composition from the printing plate is good and it is easy to form the adhesive part (B) in a predetermined shape.

The adhesive composition of the present embodiment preferably has an elongational viscosity of 1,000 mPa·s or more and 650,000 mPa·s or less, more preferably 10,000 mPa·s or more and 450,000 mPa·s or less, and 50,000 mPa·s when measured at 30°C. - It is more preferable that it is not less than s and not more than 350,000 mPa·s. By using such an adhesive composition, when forming a patterned adhesive tape, an adhesive part having good shape accuracy and shape retention can be formed. In particular, when forming an adhesive part using various printing methods, the adhesive composition is excellent in transferability from a printing plate and in shape retention of the adhesive part after transfer. Furthermore, regardless of the type of printing method used to apply the adhesive composition, an adhesive portion with good shape accuracy can be easily formed. In particular, when forming an adhesive part using a printing plate, it is possible to easily form an adhesive part with a small error in the shape and size of the adhesive part transferred and formed by the dots with respect to the shape and size of the dots on the plate.

In particular, in the method for producing a patterned adhesive tape described below, when the method for applying the adhesive composition of the present embodiment is a gravure printing method, the elongational viscosity when measured at 30° C. is 1000 mPa·s or more and 650000 mPa·s. It is preferably 1000 mPa-s or more and 500000 mPa-s or less, more preferably 1000 mPa-s or more and 75000 mPa-s or less, and 1300 mPa-s or more and 20000 mPa-s or less. More preferred. By setting the elongational viscosity of the adhesive composition used in the gravure printing method within the above range, the adhesive composition can easily flow out from the concave part of the gravure plate corresponding to the adhesive part, and the adhesive composition can be applied to the support or release liner. Things can be transferred easily. In addition, the shape retention and dimensional accuracy of the adhesive portion formed by transferring the adhesive composition to a support or the like (adhesive portion after transfer) are excellent.

In particular, in the method for producing a patterned adhesive tape described below, when the method of applying the adhesive composition of the present embodiment is a screen printing method, the elongational viscosity when measured at 30°C is 1000 mPa·s or more and 650000 mPa·s. It is preferably 50,000 mPa·s or more and 650,000 mPa·s or less, more preferably 100,000 mPa·s or more and 650,000 mPa·s or less. By setting the elongational viscosity of the adhesive composition used in the screen printing method within the above range, the adhesive composition can be held in the holes of the screen plate corresponding to the adhesive part, and during transfer, the adhesive composition can be transferred from the holes. The pressure-sensitive adhesive composition can be easily transferred to the support or release liner. In addition, the shape retention and dimensional accuracy of the adhesive portion after transfer are excellent.

The content of nonvolatile matter in the adhesive composition of the present embodiment is not particularly limited as long as it can provide a desired Truton ratio, but is preferably 15% by mass or more, and more preferably 20% by mass or more. , more preferably 25% by mass or more. Further, the content of the nonvolatile matter is preferably less than 40% by mass, particularly preferably 38% by mass or less, and more preferably 35% by mass or less. By setting the nonvolatile content of the adhesive composition within the above range, it is possible to improve suitability for various printing methods when forming an adhesive part (transferability of the adhesive composition from a printing plate and maintenance of the adhesive part after transfer). Excellent shape, etc.)

(patterned adhesive tape)
The patterned adhesive tape of one embodiment of the present invention (sometimes referred to as the adhesive tape of this embodiment) has a support (A) and an adhesive layer, and the adhesive layer has two or more adhesives. (B) and a non-adhesive region having no adhesive portion (B) between the two or more adhesive portions (B). The non-adhesive area has a pattern that extends to the outer periphery of the sheet plane.

Specific embodiments of the adhesive tape of this embodiment include a patterned adhesive tape having two or more adhesive portions (B) directly on at least one surface (a) side of the support (A); Examples include a patterned adhesive tape having the adhesive portion (B) on at least one surface (a) of the support (A) with another layer interposed therebetween.

When a double-sided patterned adhesive tape is used as the adhesive tape of the present embodiment, the support (A) has two or more of the specific adhesive parts (B) on both sides (a), and the two or more of the A double-sided adhesive tape having a structure in which a region having no adhesive portions (B) exists between the adhesive portions (B) and the region communicates with an end of the patterned adhesive tape, or the support (A ) has two or more of the specific adhesive parts (B) on one surface (a) side, and there is an area having no adhesive part (B) between the two or more adhesive parts (B), The region has a structure that communicates with the end of the patterned adhesive tape, and the other side of the support (A) has an adhesive (solid adhesive layer) on the entire surface thereof. Double-sided adhesive tape can be used.

A non-adhesive area that does not have an adhesive part (B) and is between the two or more adhesive parts (B) is a region in which a component constituting the adhesive part (B) does not exist or does not exhibit adhesive properties. This is an area where it may exist to some extent. Therefore, when the adhesive tape of this embodiment is observed from the side direction, it is observed that the adhesive portion (B) forms a convex shape with respect to the surface (a) of the support (A). Ru.

Further, in the adhesive tape of the present embodiment, the area having no adhesive part (B) between the two or more adhesive parts (B) communicates with a part of the end (outer edge part) of the patterned adhesive tape. It has a configuration. By using the patterned adhesive tape having the above structure, air bubbles escape from the interface between the patterned adhesive tape and the adherend through the area to the outside when the patterned adhesive tape is applied to the adherend. It is possible to prevent poor appearance due to swelling of the patterned adhesive tape, and to maintain excellent thermal conductivity, adhesive strength, etc.

The adhesive tape of this embodiment preferably has a total thickness of 50 μm or less, particularly preferably 20 μm or less, and more preferably 2 μm to 15 μm. , 3 μm to 10 μm is more preferable, and 3 μm to 6 μm is particularly preferable in terms of contributing to making portable electronic terminals thinner, for example. When the support (A) of the adhesive tape of this embodiment includes a foam sheet, the total thickness of the adhesive tape of this embodiment is preferably 300 μm or less, more preferably 30 μm to 250 μm, and even more preferably 50 μm to 200 μm. , 50 μm to 100 μm is particularly preferable in terms of contributing to making portable electronic terminals thinner, for example. Even though the adhesive tape of this embodiment is extremely thin as described above, it maintains excellent bubble removal properties and has excellent adhesive strength and thermal conductivity. The total thickness of the patterned adhesive tape was measured in accordance with JIS K6783 using a dial gauge under the conditions that the contact surface of the dial gauge was flat, its diameter was 5 mm, and the load was 1.23 N. This refers to the thickness of the patterned adhesive tape and does not include the thickness of the release liner. The above thickness can be measured, for example, with a thickness meter TH-102 manufactured by Tester Sangyo.

As the adhesive tape of this embodiment, it is preferable to use one having a peel adhesive strength (sometimes simply referred to as "adhesive strength") of 1N/20mm to 12N/20mm, and 1.5N/20mm to 10N/20mm. It is more preferable to use one with an adhesive strength of 20 mm, and it is preferable to use one with an adhesive strength of 3N/20mm to 8N/20mm, even if the adherend is thin. This is preferable in order to obtain a patterned adhesive tape from which air bubbles are easily removed from the interface and which has excellent adhesive strength. When even better adhesiveness is required, it is more preferable to use a patterned adhesive tape with an adhesive strength of 4N/20mm to 10N/20mm, and 4.5N/20mm to 8N/20mm. It is more preferable to use one having an adhesive strength of 20 mm.

In addition, the said adhesive force refers to the value measured according to JISZ0237. Specifically, the adhesive strength is determined by overlapping the surface having the adhesive part (B) of a patterned adhesive tape lined with a 25 μm thick polyethylene terephthalate film and a clean and smooth stainless steel plate (BA plate). The upper surface was pressurized by making one reciprocation using a 2 kg roller, and after being left for 1 hour or 24 hours under the conditions of 23 ° C and 50% RH, This is the value measured by peeling off the patterned adhesive tape. Note that the lining was performed on the surface not having the adhesive portion (B), and not on the surface having the adhesive portion (B), which is a component of the present invention. Further, when the patterned adhesive tape had the adhesive portion (B) on both sides, one of the surfaces having the adhesive portion (B) was lined.

Even if the adhesive tape of this embodiment is thin, it can prevent peeling over time or falling off of parts due to the repulsive force of the adherend or support (A), and can be used especially at relatively high temperatures. In order to prevent the above-mentioned peeling etc. even if the adhesive is removed, it is preferable to use one with an adhesive holding force of 2 mm or less, more preferably 0.5 mm or less, and 0.1 mm or less. It is further preferred to use the following:

In addition, the said adhesive holding force refers to the value measured according to JISZ0237. Specifically, the adhesive holding power is determined by overlapping the surface having the adhesive part (B) of a patterned adhesive tape lined with a 50 μm thick aluminum foil with a clean and smooth stainless steel plate (hairline). The upper surface was pressurized by making one reciprocation using a 2 kg roller, and the test piece was left for 1 hour under conditions of 23° C. and 50% RH. Next, the stainless steel plate constituting the test piece was fixed in a vertical direction in an environment of 100°C, and a load of 100 g was applied to the lower end of the patterned adhesive tape constituting the test piece, and left for 24 hours. This is a value obtained by measuring the deviation distance between the stainless steel plate and the patterned adhesive tape after the above-mentioned test using a vernier caliper.

[Support (A)]
The support (A) constituting the adhesive tape of this embodiment can be set appropriately depending on the type of support (A). For example, if the support (A) is a resin film, the thickness is 1 μm to 1 μm. It is preferable to use a thickness of 20 μm, more preferably a thickness of 1 μm to 10 μm, more preferably a thickness of 1 μm to 4 μm, and a thickness of 1.5 μm to 2.0 μm. It is more preferable to use one with a thickness of 5 μm. Further, if the support (A) is a foam sheet, one having a thickness of preferably 250 μm or less, more preferably 30 μm to 200 μm, and still more preferably 50 μm to 100 μm can be used. By setting the thickness of the support (A) within the above range, the patterned adhesive tape can be made thinner, and air bubbles can be easily removed from the interface between the surface having the adhesive portion (B) and the adherend. As a result, it is possible to more effectively prevent poor appearance and performance deterioration such as thermal conductivity and adhesive strength due to swelling of the patterned adhesive tape.

As the support (A), for example, a sheet-like support obtained using resin can be used. Specific examples of the sheet-like support (A) obtained using resin include non-foamed resin films, foam sheets, and the like.

Examples of the resin that can be used to manufacture the support (A) include polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT), polyamide (nylon), and wholly aromatic polyamide ( amide resins such as aramid), acrylic resins such as polybutyl acrylate, polyethyl acrylate, and polymethyl methacrylate (PMMA), polystyrene, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer ( Styrenic resins such as ABS resin), polyetheretherketones such as polyetheretherketone (PEEK), polyetherketoneketone, polyethersulfone (PES), polysulfone, polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polyimide (PI), polyamideimide, polyetherimide (PEI), polyesterimide, polycarbonate (PC), polyacetal, polyarylene ether (polyphenylene ether, etc.), polyphenylene sulfide, polyarylate, polyaryl, polyurethane, epoxy resin, rubber resin , elastomer, etc. can be used alone or in combination of two or more.

Among these, it is preferable to use a polyester film as the support (A) because it has little variation in thickness, has excellent tensile strength and processability, and is economical (cost). Polyethylene terephthalate film is preferred. It is more preferable to use It is preferable to use a biaxially stretched polyester film, since this can further increase the strength of the support (A) and the patterned adhesive tape obtained using the same.

The support (A) can be manufactured by molding the resin described above into a sheet shape. As a method for molding the resin into a sheet shape, a known method such as melt extrusion can be used. When the support (A) is a resin film, the resin film may be stretched or unstretched.

The support (A) may be composed of a single layer, or may be composed of multiple layers made of the same or different resins. For example, the support (A) may be a laminate including a resin film (A1) and a foam sheet (A2). When the support (A) is a laminate having a resin film (A1) and a foam sheet (A2), the resin film (A1) has an adhesive portion on one surface and a foam sheet on the other surface. It is preferable to have a body sheet (A2).

That is, the adhesive tape of the present embodiment may have at least a structure in which an adhesive part (B) is provided on one side (a) of a support (A), which is a resin film (A1), for example, and a foamed adhesive tape. It may have at least a structure in which an adhesive part (B) is provided on one surface (a) of the support body (A) which is the body sheet (A2). Further, the adhesive tape of the present embodiment has at least a structure in which an adhesive portion (B) is provided on the surface of the resin film (A1) of a laminate including, for example, a resin film (A1) and a foam sheet (A2). You may have one.

In addition, in order to further increase the adhesion with the adhesive part (B) and other adhesive layers, the support (A) may be treated with chromic acid or exposed to ozone on one or both sides. It is possible to use those that have been subjected to oxidation treatment such as treatment, flame exposure treatment, high-voltage electric shock exposure treatment, ionizing radiation treatment, etc., and those that have been formed with a primer layer or the like by using a coating agent or the like.

[Adhesive part (B)]
Next, the adhesive portion (B) constituting the adhesive tape of this embodiment will be explained.

As described above, the adhesive part (B) is provided on one or both sides of the support (A) directly or via another layer.

Between the two or more adhesive parts (B), there is a region (non-adhesive region) in which the component constituting the adhesive part (B) does not exist or may exist to such an extent that it does not exhibit adhesive properties. be.

Furthermore, the region having no adhesive portion (B) between the two or more adhesive portions (B) has a structure that communicates with a part of the end portion (outer edge portion) of the patterned adhesive tape. By using a patterned adhesive tape having the above structure, air bubbles can be easily removed from the interface when the patterned adhesive tape is applied to an adherend, thereby preventing swelling of the patterned adhesive tape. It is possible to prevent appearance defects caused by this and maintain excellent thermal conductivity, adhesive strength, etc.

The shape of the adhesive part (B) is approximately square, approximately hexagonal, approximately circular, etc. when the adhesive tape of this embodiment is observed from one surface (a) side of the support (A). can be. A substantially circular shape is preferable because air bubbles can easily escape from the interface with the adherend (air release property) and good adhesive strength can be maintained. An example of a substantially circular shape is a shape as shown in FIG. An example of a substantially hexagonal shape is a shape as shown in FIG. The adhesive portions having the shape described above are basically independent from each other, but there may be a portion where the adhesive portions are partially connected. The shape of the adhesive portion (B) may be island-like (dot-like) as shown in FIGS. 1 to 3, or may be line-like as shown in FIG. 4, for example. The line-shaped adhesive part (B) may extend at an angle that intersects the edge located in the width direction, or may extend at an angle that intersects the edge located in the flow direction, and may extend at an angle that intersects the edge located in the flow direction. It may extend at an angle that intersects the edge located in the flow direction and the edge located in the flow direction. Among these, it is more preferable that the adhesive part has a dot-like (island-like) substantially rectangular shape, substantially hexagonal shape, or substantially circular shape because it can have flow paths in multiple directions through which air bubbles can escape.

Although the substantially circular shape is not particularly limited, it is preferable that the ratio of the maximum diameter to the minimum diameter (maximum diameter/minimum diameter) of one adhesive part is 1 to 4. More preferably it is 1 to 2, most preferably 1 to 1.5. An example of a substantially circular shape is a shape as shown in FIG. The adhesive portions having the shape described above are basically independent from each other, but there may be a portion where the adhesive portions are partially connected.

Examples of the substantially square shape include shapes such as a substantially square, a substantially rectangle, a substantially trapezoid, a substantially rhombus, etc. A substantially rhombic shape as shown in FIG. 1 makes it easier for air bubbles to escape from the interface with the adherend ( It is preferable because it can maintain good adhesion (air release properties) and good adhesive strength.

In addition, "approximately" in the above-mentioned approximately square shape and approximately hexagonal shape, etc., refers to, for example, when a release liner or the like is attached to the surface of the adhesive part (B), or when the patterned adhesive tape is wound into a roll. , indicates that when the adhesive part (B) is pressed, shapes include shapes in which the corners of a square shape and a hexagonal shape are rounded, and shapes in which a straight part becomes a curved part.

It is preferable that the substantially rectangular corner portions have a substantially rhombic shape in which the angle of the corner portion facing the flow direction of the patterned adhesive tape is 90° or less. A range of 45° to 90° is more preferable because air bubbles can easily escape from the interface with the adherend (air release property) and good adhesive strength can be maintained. The substantially rhombic shape having an angle of 90° is substantially square.

Moreover, it is preferable that the adhesive part (b1) and the adhesive part (b2) constituting the two or more adhesive parts (B) do not face directly with respect to the flow direction and width direction of the patterned adhesive tape.

Further, the patterned adhesive tape is often cut into an arbitrary shape depending on the purpose and the like. At that time, since the adhesive part (b1) and the adhesive part (b2) are arranged not to face directly in the machine direction and the width direction, when the patterned adhesive tape is cut at an arbitrary position, Since the adhesive portion (B) is present in a part of the end portion, peeling of the patterned adhesive tape can be suppressed.

The distance between the adhesive part (b1) selected from the two or more adhesive parts (B) and another adhesive part (b2) that is close to (closest to) the adhesive part (b1) is 0. The thickness is preferably 5 mm or less, more preferably 0.05 mm to 0.2 mm, even more preferably 0.06 mm to 0.15 mm, and even more preferably 0.08 mm to 0.13 mm. It is particularly preferred because air bubbles can easily escape from the interface with the body (air release properties) and good adhesive strength can be maintained.

In addition, by setting the distance between the adhesive part (b1) and the adhesive part (b2) within the above range, the shape of the adhesive part and the shape of the non-adhesive region become difficult to see, and the adhesive part and the non-adhesive part It is possible to suppress the appearance defects caused by the shape of the region.

The size of each adhesive part (b1) selected from the adhesive parts (B) is preferably an area of 0.001 mm2 to 100 mm2, more preferably 0.01 mm2 to 25 mm2, and 0.015 mm2. It is more preferably from 16 mm2 to 0.02 mm2 to 5 mm2, and particularly preferably from 0.02 mm2 to 5 mm2 because air bubbles can easily escape from the interface with the adherend (air release property) and good adhesive strength can be maintained.

In addition, by setting the size of each adhesive part (b1) within the above range, the shape of the adhesive part and the shape of the non-adhesive region become difficult to visually recognize, and the shape of the adhesive part and the non-adhesive region becomes difficult to see. The occurrence of appearance defects caused by this can be suppressed.

The adhesive portion (B) preferably exists in an amount of 10 to 1,000,000 pieces, and preferably 150 to 500,000 pieces, within the area of the patterned adhesive tape of the present invention (a square of 5 cm in the machine direction and 5 cm in the width direction). It is preferable that the number of bubbles is 400 to 100,000, more preferably 1,000 to 50,000, and the number of 5,000 to 40,000 makes it easier for air bubbles to escape from the interface with the adherend. It is particularly preferred because it can maintain good adhesion (removability) and good adhesive strength.

In addition, by setting the number of the adhesive parts (B) within the above range, the shape of the adhesive part and the shape of the non-adhesive area become difficult to visually recognize, resulting in poor appearance due to the shape of the adhesive part and the non-adhesive area. can suppress the occurrence of

In addition, the patterned adhesive tape can easily release air bubbles from the interface with the adherend when pasting (air release property), maintain good adhesive strength, and adhere more easily to adherends such as graphite sheets. Even if the tape is made thinner, from the viewpoint of effectively preventing appearance defects caused by the shape of the adhesive part, the area of the patterned adhesive tape (a square of 1 cm in the flow direction and 1 cm in the width direction) is , it is preferable to use a material having 120 to 2000 adhesive parts, more preferably a material having 280 to 1600 adhesive parts, and a material having 520 to 1200 adhesive parts to be used. It is further preferred to use
In addition, the number of the above-mentioned adhesive parts is counted by observing an arbitrary range of the patterned adhesive tape (a square of 1 cm in the flow direction and 1 cm in the width direction) or (a square of 5 cm in the flow direction and 5 cm in the width direction) with an electron microscope. It can be found by

The ratio of the area having the adhesive portion (B) to the area of the one surface (a) is preferably 10% to 99%, particularly preferably 20% to 90%, and more preferably 30%. 80%, more preferably 35% to 80%. Being within the above range makes it possible to form a substantially circular adhesive part, which will be described later.As a result, air bubbles can easily escape from the interface with the adherend (air release property), and good adhesive strength can be maintained. This method is particularly preferred because patterned adhesive tapes can be produced efficiently. Note that the area ratio is the area ratio of the adhesive portion (B) in the area of a square tape measuring 5 cm in the flow direction and 5 cm in the width direction.

The thickness of the adhesive part (B) is not particularly limited, but it is preferably 1 μm to 20 μm, particularly preferably 2 μm to 15 μm, and 3 μm to 10 μm can have good adhesive strength, and the adhesive part and the adherend can have a good thickness. Air bubbles can be easily removed from the interface with (B), and as a result, poor appearance caused by blistering of the patterned adhesive tape and performance deterioration such as thermal conductivity, heat resistance, and adhesive strength can be further reduced. This is more preferable because it can be effectively prevented. The thickness of the adhesive part (B) was measured on both sides according to JIS K6783 using a method using a dial gauge under the conditions that the contact surface of the dial gauge was flat, the diameter was 5 mm, and the load was 1.23 N. Refers to the thickness of adhesive tape.

The adhesive portion (B) can be formed using the adhesive composition for a patterned adhesive tape of the present embodiment described above. Among these, it is preferable to use an adhesive part obtained using an acrylic adhesive composition as the adhesive part (B) because it has excellent adhesion reliability.

[Method for manufacturing patterned adhesive tape]
In the method for manufacturing a patterned adhesive tape according to an embodiment of the present invention (sometimes referred to as the method for manufacturing a patterned adhesive tape according to the present embodiment), the method for manufacturing a patterned adhesive tape according to the present embodiment described above is applied to the surface of the support (A). It includes an adhesive layer forming step of forming an adhesive layer using an adhesive composition for a patterned adhesive tape. The adhesive layer has two or more adhesive parts and a non-adhesive part area having no adhesive part (B) between the two or more adhesive parts (B).
The adhesive tape of this embodiment is produced by, for example, printing (coating) the above-described adhesive composition of this embodiment on at least one surface (a) of the support (A) intermittently and drying the adhesive composition. It can be manufactured by forming (B). Coating methods used for printing include gravure coating, comma coating, bar coating, die coating, lip coating, screen coating, and the like.

The adhesive composition may be applied intermittently to at least one surface (a) of the support (A) by a printing method such as a gravure printing method or a screen printing method, so that the thickness of the adhesive portion This is preferable because it is easy to adjust and the adhesive portion can be formed uniformly.

The patterned adhesive tape can also be produced by intermittently printing (coating) the adhesive composition on both sides of the support (A) and drying the adhesive composition.

In addition, the patterned adhesive tape may be formed by, for example, printing (coating) the adhesive composition intermittently on the surface of a release liner and drying it to form the adhesive part (B). It can be manufactured by transferring to at least one surface (a) side of the support (A).

Coating methods for intermittently printing (coating) the adhesive composition on the support (A) or release liner include gravure coating, comma coating, bar coating, die coating, lip coating, and screen coating. Laws, etc. can be mentioned. Among these, a method using a printing plate capable of forming the desired shape of the adhesive part (B) is preferred, and the adhesive composition is applied intermittently by a gravure printing method (gravure coating method) or a screen printing (screen coating method) method. It is preferable to do this because it is easy to adjust the thickness of the adhesive part (B) and it is easy to form the adhesive part (B) uniformly.
In the adhesive layer forming step of the method for producing a patterned adhesive tape of the present embodiment, at least one surface of the support (A) is coated with a gravure printing (coating) method or a screen printing (coating) method. It is preferable to form two or more adhesive portions (B) having a substantially circular shape, a substantially square shape, or a substantially hexagonal shape by printing (coating) the pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape.

The patterned pressure-sensitive adhesive tape of the present invention may be manufactured using, for example, a release liner as described above, and then the release liner may be peeled off as necessary, and another release liner may be attached.

The adhesive tape of this embodiment can be suitably used, for example, for bonding a housing of an electronic device such as a portable electronic terminal, a heat dissipating member such as a graphite sheet, and a heat generating member such as a rechargeable battery. The adhesive tape of this embodiment can be suitably used in the production of electronic devices such as portable electronic terminals. In particular, even if the clearance between the adherends (the area where the patterned adhesive tape is applied) is within a very narrow range of 20 μm or less in width, the adherends can be firmly bonded.

In addition, since air bubbles easily escape from the interface between the adherend and the adhesive part (B), the patterned adhesive tape is used for fixing heat dissipation sheets, magnetic sheets, etc., where there is concern that the performance may deteriorate due to the remaining air bubbles. It can be suitably used for fixed purposes, etc.

(Used for fixing heat dissipation sheets)
Many electronic devices, such as portable electronic terminals, are equipped with members that generate heat when used. Examples of the heat generating member include a rechargeable battery, a circuit board, and the like.

In order to prevent malfunctions of the electronic device, it is preferable to prevent a portion of the electronic device from becoming locally heated due to the heat generated by the member. Therefore, for the purpose of diffusing the heat, heat dissipating sheets such as heat dissipating sheets are used for the heat generating member or the members adjacent to it (for example, metal members that are frame materials used to provide rigidity to electronic devices). Often parts are attached.

As the heat dissipation member, for example, a graphite sheet or a graphene sheet is preferably used.

There are two types of graphite sheets: artificial graphite sheets and natural graphite sheets.

Examples of the artificial graphite sheet include a pyrolytic graphite sheet obtained by thermally decomposing an organic film such as a polyimide film in a high-temperature inert gas atmosphere.

The natural graphite sheet includes, for example, natural graphite treated with an acid and then heat-expanded graphite powder that is pressed into a sheet shape.

As the graphite sheet, it is preferable to use a graphite sheet with few wrinkles in order to exhibit even more excellent heat dissipation properties, and it is more preferable to use an artificial graphite sheet with few wrinkles.

The thickness of the graphite sheet is preferably 10 μm to 100 μm, and preferably 15 μm to 50 μm in terms of contributing to thinning of electronic devices such as portable electronic terminals.

On the other hand, since the graphite sheet is relatively fragile, it is generally used in the form of a graphite composite sheet with a patterned adhesive tape attached to one or both sides thereof.

As the graphite composite sheet, for example, as shown in FIG. 5, a graphite composite sheet having a structure in which a graphite sheet 4 is sealed with a single-sided patterned adhesive tape 5 and a double-sided patterned adhesive tape 6 can be used. , is preferable in order to achieve both high strength and insulation properties of the graphite sheet.

The use of a graphite composite sheet that is sealed (pouched) with a patterned adhesive tape that has a larger area than the graphite sheet prevents interlayer destruction of the graphite sheet, powder falling, etc. This is preferable because it makes it easier to achieve suitable workability.

The patterned adhesive tape of the present invention can be suitably used when pouching the graphite sheet. In this case, the patterned adhesive tape is preferably used with the surface having the adhesive portion (B) facing outside (in a direction other than the graphite sheet side). Thereby, when the graphite composite sheet and a heat generating member such as a rechargeable battery or a member adjacent thereto are bonded together, it is possible to effectively prevent air bubbles from remaining at the interface thereof.

The pasting of the graphite composite sheet and the member can be carried out, for example, by placing the graphite composite sheet on the surface of the member and temporarily adhering them together by lightly pressing them, and after the temporary adhesion, applying the material using a roller or the like. This can be done by pressing to firmly bond them together. In the temporary adhesion process, bubbles are usually present at the interface between the member and the graphite composite sheet. However, in the case of a graphite composite sheet using the patterned adhesive tape of the present invention, the air bubbles are quickly removed from the interface when pressure is applied by the roller or the like.

Further, a surface protection film is often attached to the graphite composite sheet for the purpose of preventing scratches on the surface thereof. The surface protection film is usually removed after the graphite composite sheet and the member are attached.

The patterned adhesive tape of the present invention can firmly adhere to an adherend such as a member after the air bubbles are removed, so when removing the surface protection film from the graphite composite sheet, Less likely to cause lifting or peeling from other parts.

As described above, the graphite composite sheet obtained using the patterned adhesive tape of the present invention can prevent the presence of air bubbles at the interface with an adherend such as a member, so that the patterned adhesive tape due to the presence of air bubbles can be prevented. An increase in the thermal resistance value of the tape can be effectively prevented, and as a result, the thermal conductivity in the thickness direction of the patterned adhesive tape can be improved.

(Use for magnetic sheet fixation)
Magnetic sheets are used inside electronic devices for the purpose of blocking electromagnetic waves emitted from components that make up electronic devices from leaking to the outside, and preventing electromagnetic waves generated externally from affecting electronic devices. It is often attached to.

Examples of the magnetic sheet include Ni-based ferrite magnetic powder, Mg-based ferrite magnetic powder, Mn-based ferrite magnetic powder, Ba-based ferrite magnetic powder, Sr-based ferrite magnetic powder, Fe-Si alloy powder, Fe- Sheets obtained using Ni alloy powder, Fe-Co alloy powder, Fe-Si-Al alloy powder, Fe-Si-Cr alloy powder, iron powder, Fe-based amorphous, Co-based amorphous, Fe-based nanocrystals, etc. can be used.

Generally, it is preferable to use a relatively thick magnetic sheet in order to provide good electromagnetic shielding properties.

Since the adhesive tape of this embodiment is very thin as described above, it is possible to use the magnetic sheet having the maximum thickness.

The magnetic sheet is preferably used in the form of a magnetic composite sheet with a patterned adhesive tape attached to one or both sides of the magnetic sheet for the purpose of imparting good insulation properties and high strength.

Examples of the present invention will be described below to explain it more specifically.

(Synthesis example)
"Manufacture of acrylic copolymer"
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 74.9 parts by mass of n-butyl acrylate, 10 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of cyclohexyl acrylate, 5 parts by mass of acrylic acid, 4 -0.1 part by mass of hydroxybutyl acrylate and 100 parts by mass of ethyl acetate were charged, and the temperature was raised to 75°C while stirring and blowing nitrogen.

Next, a solution of 0.1 part by mass of 2,2'-azobis(2-methylbutyronitrile) dissolved in ethyl acetate was added to the mixture, and the mixture was held at 75° C. for 8 hours with stirring.

Next, the mixture was diluted with ethyl acetate and filtered through a 200-mesh wire mesh to obtain an acrylic copolymer solution with a nonvolatile content of 40% by mass and a weight average molecular weight of 890,000.
The glass transition temperature of the acrylic polymer was -46.5°C.

"Preparation of adhesive composition"
(Preparation example 1)
For 100 parts by mass of the acrylic copolymer obtained in the above synthesis example, 5 parts of heterogeneous rosin glycerin ester (softening point 125°C), 15 parts of polymerized rosin pentaerythritol ester (softening point 125°C), aromatic An acrylic pressure-sensitive adhesive composition with a non-volatile content of 32% was prepared by diluting 15 parts of group/aliphatic hydrocarbon copolymer resin (manufactured by Mitsui Petrochemical Industries, Ltd., trade name "FTR6125", softening point 125°C) with ethyl acetate. was prepared. Subsequently, 100 parts by mass of the pressure-sensitive adhesive composition and 1.0 part of an isocyanate-based crosslinking agent (manufactured by DIC Corporation, trade name "NC40") were added and mixed by stirring so that the pressure-sensitive adhesive composition was uniformly mixed. Product (a-1) was prepared.

Using the adhesive composition (a-1), the elongational viscosity, shear viscosity, and Trouton's ratio were evaluated by the evaluation method described above. The results are shown in Table 1.

"Preparation of adhesive composition"
(Preparation Examples 2 to 6, Comparative Preparation Examples 1 to 3)
Adhesive compositions (a-1) to (a-6), ( b-1) to (b-3) were prepared.

Using the adhesive compositions (a-1) to (a-6) and (b-1) to (b-3), the elongational viscosity, shear viscosity, and Truton ratio were determined in the same manner as in Preparation Example 1. evaluated. The results are shown in Table 1.

(Example 1)
The adhesive composition (a- 1) was applied and then dried at 100° C. for 1 minute to prepare an adhesive layer with a thickness of 1 μm.

Next, the adhesive layer was transferred to one side of a support "K100-2.0W" (manufactured by Mitsubishi Plastics Co., Ltd., polyester film, thickness 2 μm) to obtain a single-sided tape.

Next, the pressure-sensitive adhesive composition (a -1) in the form of dots by gravure printing and drying at 100°C for 1 minute, the thickness of the approximately rhombic shape shown in Figure 1 with an internal angle θ = 90° (approximately square shape) A patterned adhesive tape having a total thickness of 6 μm and having an adhesive portion of 3 μm was obtained. Incidentally, among the adhesive parts, the distance between any adhesive part and the adjacent adhesive part was 0.1 mm.
In addition, the area of the adhesive part (per piece), the distance between the adhesive part (b1) and the adjacent adhesive part (b2), and the ratio of the area with the adhesive part were measured by electron microscopy (100x magnification). . The results are shown in Table 2.

"PET 25 x 1 J0L" (manufactured by Nipper Co., Ltd., a release liner having a silicone release treatment surface on the surface of a smooth PET film) was layered on the surface of the patterned adhesive tape obtained above having the adhesive part using a laminator. It was attached with a linear pressure of 3 N/mm.

(Examples 2-4, Comparative Examples 1-2)
Except for using the adhesive compositions (a-2) to (a-4) and (b-1) to (b-2) obtained in Preparation Examples 2 to 4 and Comparative Preparation Examples 1 to 2, respectively. Patterned adhesive tapes of Examples 2 to 4 and Comparative Examples 1 to 2 were obtained in the same manner as in Example 1. The obtained patterned adhesive tape was evaluated in the same manner as in Example 1, and the results are shown in Table 2. In addition, in Comparative Example 2, the adhesive composition transferred from the plate to the support by gravure printing flowed, and the adhesive layer did not become dot-like but solid, and a patterned adhesive tape could not be obtained. .

(Example 5)
Screen printing was performed using the adhesive composition (a-5) obtained in Preparation Example 5, except that a screen coater and a screen plate having the plate shape shown in Table 1 (the holes in the plate were dots) were used. A patterned adhesive tape of Example 5 was obtained in the same manner as in Example 1, except that the adhesive tape was applied in dots. The obtained patterned adhesive tape was evaluated in the same manner as in Example 1, and the results are shown in Table 2.

(Example 6, Comparative Example 3)
Example 6 and Comparative Example 3 were prepared in the same manner as in Example 5, except that the adhesive compositions (a-6) and (b-3) obtained in Preparation Example 6 and Comparative Preparation Example 3 were used, respectively. A patterned adhesive tape was obtained. The obtained patterned adhesive tape was evaluated in the same manner as in Example 1, and the results are shown in Table 2. In addition, in Comparative Example 3, the adhesive composition flowed out of the plate before printing the adhesive composition on the support, and screen printing could not be performed and a patterned adhesive tape could not be formed.

"Evaluation method of adhesive composition"
(Non-volatile content)
The nonvolatile content of the adhesive composition was calculated from the nonvolatile content of the acrylic copolymer and the amount of ethyl acetate used for dilution.

(elongational viscosity, shear viscosity, Trouton ratio)
The adhesive compositions (a-1) to (a-6) and (b-1) to (b-3) of Examples 1 to 6 and Comparative Examples 1 to 3 shown in Table 1 are shown below, respectively. Using this method, the elongational viscosity at an elongation rate of 4000 s ^-1 and the shear viscosity at a shear rate of 4000 s ^-1 were measured, and the Trouton ratio, which is the ratio thereof (elongational viscosity/shear viscosity), was determined.
The extensional viscosity was measured according to the capillary rheometer evaluation method described in JIS-7199 (ISO 11443, ASTM D 3835).

Specifically, a twin capillary type device (manufactured by Gottfert; RHEOGRAPH20) was used. A capillary die with a length of 30 mm and a diameter of 0.3 mm and a capillary die with a length of 0.25 mm and a diameter of 0.3 mm were used in combination.

Then, from the apparent shear viscosity (pressure) measured at a temperature of 30° C. and a shear rate of 1000 to 300000 s ⁻¹ , pressure loss was removed using Bergley correction to obtain the true shear viscosity. From the obtained true shear viscosity and pressure drop, the extensional viscosity corresponding to the extension rate was determined using the Cogswell equation.
Table 1 shows the elongational viscosity at an elongation rate of 4000 s ^-1 , the shear viscosity at a shear rate of 4000 s ^-1 , and the Trouton's ratio.

<Production of graphite composite sheet>
A single-sided patterned adhesive tape "IL-05G" (manufactured by DIC Corporation) measuring 104 mm long x 104 mm wide x 5 μm thick was pasted on one side of a graphite sheet measuring 100 mm long x 100 mm wide x 25 μm thick, and the graphite sheet On the other side of the sheet, the patterned adhesive tapes obtained in the Examples and Comparative Examples were cut into a size of 104 mm in length x 104 mm in width and then pasted thereon.

At that time, among the adhesive layers constituting the patterned adhesive tape, the adhesive layer having a smooth surface was oriented in contact with the graphite sheet.

Next, a graphite composite sheet was formed by laminating a slightly adhesive single-sided tape "CPF50(25)-SP" (manufactured by Nipper Co., Ltd.) with a thickness of 62 μm on the surface of the single-sided patterned adhesive tape "IL-05G". Obtained.

"Evaluation method for patterned adhesive tape"
(Measurement of adhesive layer)
The shape, size, etc. of the adhesive part were measured using an electron microscope (100x magnification).
The thicknesses of the adhesive portion, adhesive layer, and adhesive tape were measured using a dial gauge (manufactured by Tester Sangyo).

(Evaluation of adhesive part shape)
Using an electron microscope (100x magnification), the area of each adhesive part (per piece) and the distance between the adhesive part (b1) and the adjacent adhesive part (b2) were measured. The percentage of the area having adhesive parts was calculated from the total area of the adhesive parts.

(Adhesive strength (1 hour after pasting))
The patterned adhesive tapes obtained in Examples and Comparative Examples were cut into 20 mm width pieces, and the adhesive layer on one side of the tapes was lined with a 25 μm thick polyethylene terephthalate film to prepare test pieces. The lining was performed on the surface of the adhesive layer having a smooth surface, and was not performed on the adhesive layer corresponding to the adhesive part (B) which is a component of the present invention.

The test piece was attached to the surface of a clean and smooth stainless steel plate, and the top surface was pressurized by moving a 2 kg roller back and forth once under the conditions of 23°C and 50% RH according to JISZ-0237. After leaving it for 1 hour, the peel adhesive force (peel direction: 180°, tensile speed: 0.3 m/min) was measured using a Tensilon tensile tester in an atmosphere of 23° C. and 50% RH. The measurement results are shown in the column of "Adhesive strength (1 hour after application)" in the table.

(Adhesive strength (24 hours after pasting))
The patterned adhesive tapes obtained in Examples and Comparative Examples were cut into 20 mm width pieces, and the adhesive layer on one side of the tapes was lined with a 25 μm thick polyethylene terephthalate film to prepare test pieces. The lining was performed on the surface of the adhesive layer having a smooth surface, and was not performed on the adhesive layer corresponding to the adhesive part (B) which is a component of the present invention.

The above test piece was attached to the surface of a clean and smooth stainless steel plate, and the top surface was pressurized by moving it back and forth once using a 2 kg roller. According to JIS Z-0237, the test piece was applied under the conditions of 23°C and 50% RH. After being left for 24 hours under an atmosphere of 23° C. and 50% RH, the peel adhesive force (peel direction: 180°, tensile speed: 0.3 m/min) was measured using a Tensilon tensile tester. The measurement results are shown in the column of "Adhesive strength (24 hours after application)" in the table.

(holding force)
The patterned adhesive tapes obtained in Examples and Comparative Examples were cut into 20 mm width pieces, and the adhesive layer on one side of the tapes was lined with aluminum foil having a thickness of 50 μm to prepare test pieces. The lining was performed on the surface of the adhesive layer having a smooth surface, and was not performed on the adhesive layer corresponding to the adhesive part (B) which is a component of the present invention.

The above test piece was pasted on the surface of a clean and smooth stainless steel plate so that the pasting area was 20 mm x 20 mm, and the top surface was pressurized by moving it back and forth once using a 2 kg roller. Similarly, after being left for 1 hour under the conditions of 23° C. and 50% RH, a load of 100 g was applied in the shear direction in an atmosphere of 100° C., and the distance of tape deviation after 24 hours was measured. The measurement results are shown in the "holding power" column of the table.

[Evaluation method for bubble removal 1 (ease of removal)]
Peel off the release liner of the graphite composite sheet, place an aluminum plate measuring 200 mm long x 200 mm wide on the surface of the adhesive part at 23°C and 50% RH, and leave it for 5 seconds with a load of 10 N applied from above the aluminum plate. A temporary patch was obtained by doing this.

Next, after inverting the temporary attachment, a 2 kg roller was moved back and forth once from the graphite composite sheet side to pressurize them to obtain a laminate.

Ten laminates were produced using the above method. The presence or absence of air bubbles between the adhesive layer of the graphite composite sheet constituting the laminate and the aluminum plate was confirmed by visually observing the swelling of the graphite sheet. The ease with which the bubbles came out was evaluated based on the number of laminates in which the presence of bubbles could not be confirmed by the above method.

[Evaluation method for bubble removal 2 (ease of removal)]
"PET25X1J0L" (manufactured by Nipper Co., Ltd., release liner with a smooth release surface, Ra = 0.03 μm) was pasted on the surface of the adhesive part that appeared by peeling off the release liner of the graphite composite sheet, and then the laminator was used. After applying pressure at a linear pressure of 3 N/mm using a vacuum cleaner, the sample was left in an environment at 23° C. for one day.

After that, the "PET25X1J0L" was peeled off, and an aluminum plate of 200 mm in length x 200 mm in width was placed on the surface of the adhesive part that appeared after the peeling in an atmosphere of 23°C and 50% RH, and a load of 10 N was applied from above the aluminum plate. A temporary patch was obtained by leaving it for 5 seconds.

Next, after inverting the temporary attachment, a 2 kg roller was moved back and forth once from the graphite composite sheet side to pressurize them to obtain a laminate.

Ten laminates were produced using the above method. It was confirmed whether or not air bubbles were present between the adhesive portion of the graphite composite sheet constituting the laminate and the aluminum plate by visually observing the swelling of the graphite sheet. The ease with which the bubbles came out was evaluated based on the number of laminates in which the presence of bubbles could not be confirmed by the above method.

(Whether or not the graphite composite sheet lifts when the slightly adhesive film is peeled off)
On the surface of the single-sided patterned adhesive tape "IL-05G" (manufactured by DIC Corporation) constituting the graphite composite sheet, a slightly adhesive film (75 μm thick PET film with a silicone slightly adhesive layer on one side: The laminated product with adhesive force = 0.05 N/20 mm) was placed on an aluminum plate, and the surface was moved back and forth once with a 2 kg roller to adhere them.

One minute after the pasting, the slightly adhesive film was peeled off from the surface of the graphite composite sheet in a 180° direction at a speed of 5 m/min, and whether or not the graphite composite sheet was lifted from the surface of the aluminum plate. was visually evaluated. Ten laminates were produced for each of the graphite composite sheets obtained in Examples and Comparative Examples, and the above tests were conducted. The number of laminates in which lifting of the graphite composite sheet from the surface of the aluminum plate was not confirmed in the above test is listed in the table below.

(Appearance evaluation method)
The graphite composite sheet was attached to an aluminum plate, and evaluation was made based on whether the shape of the adhesive part could be visually recognized when observed from a position 30 cm above the graphite composite sheet under a fluorescent lamp. Those in which the shape of the adhesive part could not be seen at all were rated as "◎", those in which part of the shape could be slightly seen were rated as "○", and those in which the shape could be clearly seen were rated as "×". . In Comparative Examples 2 and 3, no adhesive portion was formed and the shape of the adhesive portion could not be visually recognized by the above method, so it was not evaluated and was given a “-”.
[Number of adhesive parts]
The number of adhesive parts was determined by observing and counting an arbitrary range of the patterned adhesive tape (a square of 5 cm in the flow direction and 5 cm in width) using an electron microscope.

"Approximately diamond-shaped" in the table refers to a diamond-shaped adhesive part in which the angle of the corner facing the flow direction of the patterned adhesive tape is 90° (the angle of the corner facing the width direction is 90°). Figure 1). In other words, "approximately rhombus (θ = 90°)" in the table refers to the shape of the adhesive portion shown in FIG. point to

(Consideration)
An adhesive composition having a Trouton ratio within a predetermined range has good transferability from a printing plate when manufacturing a patterned adhesive tape, and forms an adhesive part with good shape accuracy and shape retention. was completed. Therefore, the patterned adhesive tape of the example has excellent bubble removal properties and adhesive strength. Furthermore, the patterned adhesive tape of the example was less likely to lift when attached to a graphite composite sheet.
On the other hand, pressure-sensitive adhesive compositions whose Trouton ratio was not within the predetermined range were poor in transferability from a plate when producing a patterned pressure-sensitive adhesive tape, and in shape accuracy and shape retention of the adhesive portion after transfer. Therefore, in the patterned adhesive tape of the comparative example, it was difficult to achieve both ease of bubble removal and adhesiveness.
Specifically, in Comparative Example 1, the Trouton ratio of the adhesive composition was too high, so when the adhesive composition was transferred from the plate to the support, it was difficult for the adhesive composition to come out from the plate, resulting in poor transferability. As a result, the obtained adhesive part had a shape different from the plate shape (dot shape), the dimensions were small, and the shape accuracy was reduced. Therefore, in the patterned adhesive tape of Comparative Example 1, the adhesive part (B) is not approximately diamond-shaped (θ = 90°) corresponding to the plate shape (dot shape), but has a shape close to a circle, and as the shape changes due to transfer, the adhesive part (B) becomes sticky. Since the size of part (B) also became smaller, the area ratio became smaller (the adhesive area with the adherend was reduced). As a result, the patterned adhesive tape of Comparative Example 1 did not have adhesive strength.
In addition, in Comparative Example 2, the Trouton ratio of the adhesive composition was too low, so when the adhesive composition was transferred from the plate to the support, the adhesive composition flowed on the support and the adhesive part It couldn't hold its shape. Therefore, in the adhesive tape of Comparative Example 2, the adhesive layer was smooth, and the shape of the adhesive part (B) could not be maintained, and the spaces between the adhesive parts (B) were filled, resulting in a solid state (patterned non-conformity). no adhesive area was formed). As a result, in the adhesive tape of Comparative Example 2, there was no way for air bubbles to escape, and the ease with which air bubbles escaped was extremely poor.
In Comparative Example 3, the Trouton ratio of the adhesive composition was too low, so the adhesive composition could not be retained on the plate from the time the adhesive composition was placed on the plate until it was transferred to the support, and the adhesive composition did not transfer to the support. It was not possible to form an adhesive portion on top.

In Example 6, the size of the adhesive part (B) was larger than the dot size of the plate, and the distance between the adhesive parts (B) was narrower, so air bubbles were easier to escape compared to other examples. inferior.

1 Support 2 Adhesive part 3 Patterned adhesive tape 4 Graphite sheet 5 Single-sided patterned adhesive tape 6 Double-sided patterned adhesive tape

Claims (8)

An adhesive composition for a patterned adhesive tape, which is used for forming a patterned adhesive tape,
The pressure-sensitive adhesive composition for patterned pressure-sensitive adhesive tape has a Trouton ratio of 8 or more and 400 or less when measured at 30°C,
The patterned adhesive tape has an adhesive layer,
The adhesive layer has two or more adhesive portions (B) and a non-adhesive region having no adhesive portion (B) between the two or more adhesive portions (B),
A pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape, wherein the non-adhesive region has a pattern extending to the outer periphery of a flat sheet. including a support (A) and an adhesive layer,
The adhesive layer is formed using the adhesive composition for patterned adhesive tape according to claim 1,
The adhesive layer has two or more adhesive portions (B) and a non-adhesive region having no adhesive portion (B) between the two or more adhesive portions (B),
A patterned adhesive tape, wherein the non-adhesive region has a pattern that extends to the outer periphery of the sheet plane. A claim in which the shape of the adhesive portion (B) when observed from one surface (a) side of the support (A) is approximately circular, approximately square, or approximately hexagonal. Item 2. Patterned adhesive tape according to item 2. 2. A distance between an arbitrary adhesive part (b1) selected from the two or more adhesive parts (B) and an adhesive part (b2) adjacent to the adhesive part (b1) is 0.5 mm or less, or 3. The patterned adhesive tape according to 3. The patterned adhesive tape according to claim 2 or 3, wherein the area having the adhesive portion (B) occupies 10% to 99% of the area of one side (a) of the support (A). A smooth stainless steel plate was placed on the surface having the adhesive part (B), and they were pressed together by making one reciprocation using a 2 kg roller, and left under the conditions of 23 ° C. and 50% RH for 1 hour. The patterned adhesive tape according to claim 2 or 3, which has a 180° peel adhesive strength of 2 N/20 mm to 12 N/20 mm as measured using a test piece. A pressure-sensitive adhesive layer forming step of forming a pressure-sensitive adhesive layer on the surface of the support (A) using the pressure-sensitive adhesive composition for a patterned pressure-sensitive adhesive tape according to claim 1,
A method for producing a patterned adhesive tape, wherein the adhesive layer has two or more adhesive parts and a non-adhesive region having no adhesive part (B) between the two or more adhesive parts (B). In the adhesive layer forming step, by applying the adhesive composition for a patterned adhesive tape to at least one surface of the support (A) by a gravure printing method or a screen printing method, a substantially circular shape, 8. The method for producing a patterned adhesive tape according to claim 7, wherein two or more adhesive portions (B) are formed in a substantially square shape or a substantially hexagonal shape.

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