TWI719180B - Adhesive flakes on both sides - Google Patents

Abstract

Provided is a double-sided adhesive sheet, which is a double-sided adhesive sheet having a first adhesive layer and a second adhesive layer on both sides of a support, wherein the support includes polylactic acid, and the thickness of the support is 1.5 μm or less . The double-sided adhesive sheet can fully exhibit high adhesive force even if it is made into a thin film, and the effect of inhibiting the separation of residual glue is excellent.

Description

Adhesive flakes on both sides

The present invention relates to adhesive sheets on both sides.

In addition to the composition and polarity of the adhesive, the adhesive force of the adhesive sheet also depends on the coating amount of the adhesive on the support, that is, the thickness of the formed adhesive layer. In other words, generally speaking, the thicker the adhesive sheet, the higher the adhesive force of the adhesive sheet.

Although the thickness of the adhesive layer of the adhesive sheet of labels, tapes, etc. is appropriately set according to the purpose of the adhesive sheet, the reduction of the adhesive force is taken into account, so it is not possible to reduce the thickness to less than 10μm.

However, in recent years, there is a demand for thinning in electronic equipment or optical equipment. For the bonding of components used in such electronic equipment or optical equipment, or for temporary bonding during processing, it is required to reduce the thickness of the adhesive sheet. It also has the characteristics of high adhesion.

In order to meet such requirements, various adhesive sheets are proposed.

For example, Patent Document 1 discloses a double-sided adhesive tape, which is made of polyethylene terephthalate with a thickness of 0.002~0.012mm (PET) films and other supports have adhesive layers on both sides, with a total thickness of 0.003mm or more but less than 0.03mm, and a breaking strength of 2~26MPa/10mm width.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2005-105212 A

In addition, there are cases where two members provided in thinned electronic devices or optical devices are joined via adhesive sheets on both sides. In order to meet the requirements of thinner machines, the gap between the two joined members is often narrow. Therefore, the double-sided adhesive sheet used for bonding is required to be thinner.

As a means corresponding to the requirement of a more thin film of the double-sided adhesive sheet, the thinning of each layer of the adhesive layer or the support constituting the double-sided adhesive sheet is considered.

However, when the adhesive layer is further thinned, the adhesive force will decrease, and there is a concern that the joining of the two members is insufficient.

On the other hand, the thinning of the support is limited in terms of the manufacturing or strength of the support. For example, in the double-sided adhesive sheet described in Patent Document 1, setting the thickness of the PET film used as a support to less than 2 μm is extremely difficult from the viewpoint of molding.

In addition, as a means of thinning the double-sided adhesive sheet, it is also considered that there is no support (core material), but a double-sided adhesive sheet with a structure in which the adhesive layer is sandwiched by two release materials to reduce the support ( The thickness of the core material).

However, if the support (core material) is omitted, when one of the two peeling materials is peeled off, the specific interface where the peeling material should be peeled cannot be used for peeling, and the adhesive layer will cohesively break. The so-called "residual glue separation phenomenon" in which part of the release material adheres to both sides and the adhesive layer remains.

In addition, in Patent Document 1, there is no discussion on the use of maintaining the adhesive force of the double-sided adhesive sheet while further thinning, and avoiding the "residual glue separation phenomenon" accompanying the thinning of the adhesive layer.

The present invention was made in view of the above-mentioned problems, and its object is to provide a double-sided adhesive sheet that can fully exhibit high adhesive force even if it is formed into a thin film, and has an excellent effect of suppressing the residual glue separation phenomenon.

The inventors found that in a double-sided adhesive sheet with adhesive layers on both sides of a support, the above-mentioned problems can be solved by using a support containing polylactic acid and adjusting the thickness of the support to a specific value or less.

That is, the present invention provides the following [1] to [8].

[1] A double-sided adhesive sheet, which is a double-sided adhesive sheet having a first adhesive layer and a second adhesive layer on both sides of a support, wherein The support includes polylactic acid, and the thickness of the support is 1.5 μm or less.

[2] The double-sided adhesive sheet as in [1] above, wherein the film strength of the aforementioned support is 1 to 300 mN.

[3] The double-sided adhesive sheet according to [1] or [2] above, wherein the content of the polylactic acid is 70-100% by mass relative to the total mass of the support.

[4] The double-sided adhesive sheet according to any one of [1] to [3] above, wherein at least one of the first adhesive layer and the second adhesive layer is formed of an acrylic adhesive containing acrylic resin的层。 The layer.

[5] The double-sided adhesive sheet according to any one of the above [1] to [4], wherein the thickness of the first adhesive layer and the second adhesive layer are independently 0.5 to 3.0 μm.

[6] The double-sided adhesive sheet of any one of [1] to [5] above, wherein the ratio of the thickness of the aforementioned support to the total thickness of 100 of the first adhesive layer and the second adhesive layer is 5.0~ 70.0.

[7] The double-sided adhesive sheet according to any one of [1] to [6] above, wherein the total thickness of the double-sided adhesive sheet when attached to two adherends via the aforementioned double-sided adhesive sheet is 6.0 μm or less .

[8] The double-sided adhesive sheet of any one of [1] to [7] above, which is attached to a stainless steel plate (SUS304 steel plate, 120 grinded) under an environment of 23°C and 50% RH (relative humidity) After 24 hours, the adhesive force measured in accordance with JIS Z0237:2000 is 1.5N/25mm or more.

The double-sided adhesive sheet of the present invention can fully exhibit high adhesive force even if it is thinned, and the effect of inhibiting the separation of residual glue is excellent.

1, 2‧‧‧ Adhesive sheets on both sides

11‧‧‧Support

12a‧‧‧The first adhesive layer

12b‧‧‧Second adhesive layer

13a、13b‧‧‧Striping material

[Figure 1] is a cross-sectional view of the double-sided adhesive sheet showing the structure of the same state of the double-sided adhesive sheet of the present invention.

In this specification, the thickness of each layer constituting the double-sided adhesive sheet and the total thickness of the double-sided adhesive sheet mean the value measured by the spectroscopic analysis of reflected light, specifically, the value measured by the method described in the examples.

In this specification, the value of the mass average molecular weight (Mw) means the value measured in terms of standard polystyrene measured by the gel permeation chromatography (GPC) method, specifically, the value measured according to the method described in the examples value.

In this specification, for example, "(meth)acrylate" refers to the terms of both acrylate and methacrylate, and other similar terms are also the same.

[Structure of Adhesive Sheet on Both Sides]

The double-sided adhesive sheet of the present invention is as long as it has a first adhesive layer and a second adhesive layer on both sides of the support (hereinafter, also collectively referred to as "adhesive There is no particular limitation on the term "adherent layer").

Fig. 1 is a cross-sectional view of the double-sided adhesive sheet showing the structure of the same state of the double-sided adhesive sheet of the present invention.

As a double-sided adhesive sheet of the same aspect of the present invention, for example, a first adhesive layer 12a and a second adhesive layer 12a and a second adhesive layer are directly laminated on both sides of the support 11 as shown in FIG. 1(a). The structure of 12b has sheets 1 attached to both sides.

In addition, from the viewpoint of operability, as shown in Figure 1 (b), a release material may be further laminated on the surfaces of the first adhesive layer 12a and the second adhesive layer 12b, respectively. Sheet 2 is adhered to both sides of 13a and 13b.

In addition, as the double-sided adhesive sheet in the same aspect of the present invention, it may be a peeling material having both sides of the first adhesive layer 12a and the second adhesive layer 12b laminated on the surface of any one of the peeling treatments, It is rolled into a roll structure with adhesive sheets on both sides.

That is, the double-sided adhesive sheet of the same aspect of the present invention may have a structure in which a release material is further laminated on one or both of the first adhesive layer and the second adhesive layer.

As the total thickness of the two-sided adhesive sheet when attaching two objects via the two-sided adhesive sheet of the present invention, it can be made into a double-sided adhesive sheet that can also be used for joining two parts with a narrow gap. In other words, it is preferably 6.0 μm or less, more preferably 5.0 μm or less, still more preferably 4.0 μm or less, still more preferably 3.5 μm or less, particularly preferably 3.0 μm or less.

The double-sided adhesive sheet of the present invention is even thinner than 6.0μm, It can also fully exhibit high adhesion, and can effectively inhibit the separation of residual glue.

On the other hand, from the viewpoint of making a double-sided adhesive sheet that exhibits excellent adhesion and effectively suppresses the phenomenon of residual glue separation, the two sides of the adhered body are attached via the double-sided adhesive sheet of the present invention. The total thickness of the adhesive sheet is preferably 1.5 μm or more, more preferably 1.7 μm or more, and still more preferably 2.0 μm or more.

In addition, in this specification, "thinned double-sided adhesive sheet" means that the total thickness of the double-sided adhesive sheet is adjusted to 6.0μm or less when the two-sided adhesive sheet is attached to two adherends through the two-sided adhesive sheet. Thin slices.

Furthermore, in this manual, "the total thickness of the two-sided adhesive sheet when attaching two adherends through the two-sided adhesive sheet" means to deduct the layer of the peeling material that is removed when attaching to the adhered body. The thickness of the double-sided adhesive sheet after the thickness, for example, means the thickness indicated by "Z1" in the double-sided adhesive sheet 1 shown in Figure 1, and the thickness indicated by "Z2" in the double-sided adhesive sheet 2 thickness.

That is to say, in the "total thickness of the two-sided adhesive sheet when attaching two objects through the two-sided adhesive sheet", although it does not include the peeling of the two-sided adhesive sheet 2 shown in Figure 1 (b) The thickness of the materials 13a and 13b, but, for example, the thickness of the support body and the layer other than the adhesive layer, which are not removed when attached to the body, are included.

Examples of layers other than the support and the adhesive layer that are not removed when attached to the body include: primer layer, antistatic layer, and ultraviolet rays The absorbent layer, etc., these layers are preferably provided between the support and the first adhesive layer or the second adhesive layer.

In the double-sided adhesive sheet of the same aspect of the present invention, the ratio of the thickness of the support to the total thickness of the first adhesive layer and the second adhesive layer of 100 is preferably 5.0-70.0, more preferably 5.2-50.0, More preferably, it is 5.5~40.0, still more preferably is 6.0~30.0, and particularly preferably is 6.2~20.0.

If the ratio is within the above range, a double-sided adhesive sheet that exhibits excellent adhesion and can effectively suppress the separation of residual glue can be obtained. In addition, it is possible to suppress the breakage of the double-sided adhesive sheet that is likely to occur during attachment or peeling.

Hereinafter, the details of the support, the adhesive layer (first and second adhesive layers), and the release material constituting the double-sided adhesive sheet of the present invention will be described.

<Support body>

The supporting system of the double-sided adhesive sheet of the present invention contains polylactic acid and has a thickness of 1.5 μm or less.

Universal resins such as polyethylene terephthalate (PET) or polyurethane, which are the constituent resins used in the support of general adhesive sheets, are usually formed as thin as possible in the general forming method. There are difficulties in the matter of less than 1.5μm.

In addition, even if a support body with a thickness of 1.5 μm or less is obtained by using a general-purpose resin such as PET or polyurethane by a special molding method, Due to the use of this support, the effect of improving adhesion cannot be displayed.

On the other hand, the support body containing polylactic acid is highly self-supporting, so it can be molded to a thickness of 1.5 μm or less.

In addition, the present inventors have found that the double-sided adhesive sheet with adhesive layers provided on both sides of a support containing polylactic acid has a very high adhesive force improvement effect. In particular, even if it is thinned, it can exhibit high adhesive force. According to this finding , And complete the two-sided adhesive sheet of the present invention.

In particular, the support containing polylactic acid has high self-supporting properties and moderate flexibility even if the thickness is reduced to 1.5 μm or less.

Therefore, it can be inferred that the double-sided adhesive sheets with thin-filmed adhesive layers are provided on both sides of the support. When attached to the adherend, it is due to the excellent followability to the surface of the adherend, and even if the adhesive is applied The layer is thinned, and it can also show excellent adhesion.

Furthermore, a double-sided adhesive sheet with adhesive layers on both sides of a support such as a general PET film is divided into two adhesive layers due to the support, and the adhesive force of the other adhesive layer will increase with that of the adhesive. It is difficult to guess that the flexibility of the layer changes.

In other words, the adhesive force of each adhesive layer basically only depends on the structure or characteristics of the respective adhesive layer, and the structure or characteristics of the other adhesive layer is minimally affected.

On the other hand, in the double-sided adhesive sheet of the present invention, since the support containing polylactic acid is thinned to 1.5 μm or less, for example, the support is interposed based on the flexibility and other characteristics of the adhesive layer on one side. Contribute to the improvement of the adhesive force of the adhesive layer of the other party.

As a result, it can be presumed that the double-sided adhesive sheet of the present invention can exhibit excellent adhesive power on both sides even when it is thinned.

In addition, the double-sided adhesive sheet of the present invention has a support as a structure, and therefore, can effectively suppress the separation of residual glue.

Although the thickness of the support used in the present invention is 1.5 μm or less, it is preferably 1.2 μm or less, more preferably 1.0 μm or less, still more preferably 0.8 μm or less, and still more preferably 0.6 μm or less, particularly preferably It is 0.4 μm or less.

The double-sided adhesive sheet using a support with a thickness of more than 1.5 μm is because the support itself is hard, so the followability to the surface of the object is reduced, and as a result, the adhesive force is likely to decrease.

In addition, although the lower limit of the thickness of the support is not limited, from the viewpoint of making a double-sided adhesive sheet that can effectively suppress the separation of residual glue, and suppress the double-sided adhesive sheet that may occur during attachment or peeling From the viewpoint of breaking, it is preferably 0.01 μm or more, more preferably 0.05 μm or more, and still more preferably 0.10 μm or more.

In the present invention, "polylactic acid" refers to a polymer having a structural unit (1) represented by the following formula (I), and the polymer may have a structural unit other than the structural unit (1).

In addition, the structural unit (1) may be a structure derived from L-lactic acid The structural unit may also be a structural unit derived from D-lactic acid.

That is to say, polylactic acid can be poly-L-lactic acid which is a homopolymer of L-lactic acid, it can also be poly-D-lactic acid which is a homopolymer of D-lactic acid, or it can be L-lactic acid and D-lactic acid.的copolymer.

Among these, the polylactic acid is preferably a copolymer of L-lactic acid and D-lactic acid.

In the case of using a copolymer of L-lactic acid and D-lactic acid, as the molar ratio of the structural unit derived from L-lactic acid to the structural unit derived from D-lactic acid in the copolymer ([L-lactic acid]/[D -Lactic acid]), preferably 10/90~90/10, more preferably 20/80~80/20, still more preferably 30/70~70/30, and still more preferably 40/60~60/ 40.

By setting the molar ratio as a copolymer in the above-mentioned range, crystallinity can be appropriately maintained, and the support system including the copolymer can be adjusted so as to have an appropriate hardness. As a result, when the obtained adhesive sheet is attached to the adherend, the followability to the surface of the adherend is excellent, and it is easy to exhibit excellent adhesive force.

The mass average molecular weight (Mw) of polylactic acid is preferably 20,000 to 500,000, more preferably 50,000 to 400,000, and still more preferably 70,000 to 300,000.

The support used in the same aspect of the present invention may also contain resins or additives other than polylactic acid within a range that does not impair the effects of the present invention.

Examples of resins other than polylactic acid that can be contained in the support include polyethylene terephthalate, polybutylene terephthalate, and polynaphthalene Polyester resins such as ethylene dicarboxylate, urethane resins such as urethane acrylate, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinylidene chloride -Based resins, polyvinyl alcohol-based resins, ethylene-vinyl acetate copolymers, polystyrene-based resins, polycarbonate-based resins, acrylic resins, norbornene-based resins, cycloolefin resins, etc.

Examples of additives that can be contained in the support include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip aids, anti-blocking agents, and colorants.

The support system used in the same aspect of the present invention only needs to contain polylactic acid. For example, it is not only a support formed by molding a resin composition containing polylactic acid, but also a resin, paper, etc. other than polylactic acid. Or a support composed of a metal foil such as aluminum and copper laminated with a resin composition containing polylactic acid, etc.

However, from the viewpoint of manufacturing a support having a thickness of 1.5 μm or less, the support used in the same aspect of the present invention is preferably a single-layer support formed by molding a resin composition containing polylactic acid.

In addition, the aforementioned resin composition may contain resin components other than polylactic acid or various additives within a range that does not impair the effects of the present invention.

The content of the polylactic acid contained in the support used in the same aspect of the present invention is the viewpoint of making a double-sided adhesive sheet that can fully exhibit high adhesive force even if it is made into a thin film, and it can be used to make supports with a thickness of 1.5 μm or less From the point of view of the body, relative to the total mass (100% by mass) of the support, it is preferably 70-100% by mass, more preferably 80-100% by mass, still more preferably 90-100% by mass, and again More preferably, it is 95-100% by mass.

In particular, the content of the copolymer of L-lactic acid and D-lactic acid contained in the support used in the same aspect of the present invention is preferably 60-100 relative to the total mass (100% by mass) of the support. % By mass, more preferably 70-100% by mass, still more preferably 80-100% by mass, still more preferably 90-100% by mass, particularly preferably 95-100% by mass.

The film strength of the support used in the same aspect of the present invention is a double-sided adhesive sheet that can fully exhibit high adhesive force even if it is made into a thin film. It is preferably 1 to 300 mN, more preferably 3 to 250 mN. , More preferably 5~200mN, still more preferably 10~130mN, particularly preferably 15~90mN.

If the film strength of the support is within the above-mentioned range, even if two-sided adhesive sheets with thinned adhesive layers are provided on both sides of the support, the The followability is also excellent, and it is easy to show excellent adhesion.

In addition, in this specification, the film strength of the support means a value measured in accordance with JIS Z1707 (1997), specifically, a value measured in accordance with the method and conditions described in the examples.

<The first adhesive layer and the second adhesive layer>

The double-sided adhesive sheet of the present invention has a first adhesive layer and a second adhesive layer on both sides of the support, respectively.

As the thickness of each of the first adhesive layer and the second adhesive layer, each independently, preferably 0.5 to 3.0 μm, more preferably 0.7 to 2.0 μm, still more preferably 0.8 to 1.8 μm, and still more preferably It is 0.9~1.6μm.

The double-sided adhesive sheet of the present invention has a support containing polylactic acid and a thickness of 1.5 μm or less. Therefore, even if the thickness of each adhesive layer is thinned to 3.0 μm or less, it can be made to fully exhibit high adhesive force. Adhesive flakes on both sides.

In addition, the total thickness of the first adhesive layer and the second adhesive layer is preferably 1.0 to 6.0 μm, more preferably 1.4 to 4.0 μm, still more preferably 1.6 to 3.6 μm, and still more preferably 1.8 ~3.2μm.

There are no particular restrictions on the adhesive system used as the material for forming the first adhesive layer and the second adhesive layer, as long as the adhesive layer is made into a thin film that can sufficiently exhibit high adhesive strength. For example, it may include one or more Adhesive resin selected from acrylic resins, urethane resins, rubber resins, silicone resins, vinyl ether resins, polyester resins, and polyolefin resins.

However, from the viewpoint of sufficiently maintaining a high adhesive force regardless of the environment, the adhesive resin is preferably an ultraviolet non-curable resin.

In addition, in this specification, the ultraviolet non-curable resin system means a resin that does not have a polymerizable functional group that can be polymerized by irradiation with ultraviolet rays.

In addition, the adhesive may contain, for example, a cross-linking agent, a tackifier, an ultraviolet absorber, an antioxidant, a preservative, an anti-mold agent, a plasticizer, a defoamer, and the like within a range that does not impair the effects of the present invention. Additives for adhesives such as wettability modifiers.

However, from the viewpoint that the high adhesive force can be sufficiently maintained regardless of the environment, the higher the content of the oligomer component having polymerizable functional groups in the adhesive is As little as possible.

The content of the oligomer component having a polymerizable functional group relative to 100 parts by mass of the adhesive resin contained in the adhesive is preferably less than 5 parts by mass, more preferably less than 1 part by mass, and still more preferably It is less than 0.01 part by mass, and more preferably less than 0.001 part by mass.

In addition, the adhesive layer is formed by applying an adhesive on a support or a release material. However, in order to easily form a thin adhesive layer, the adhesive may be diluted with an organic solvent to prepare an adhesive solution.

Examples of the organic solvent include toluene, ethyl acetate, methyl ethyl ketone, etc., but the organic solvent used in the synthesis of the resin contained in the adhesive layer may be used as it is.

The solid content concentration of the solution of the adhesive is preferably 5-60% by mass, more preferably 10-40% by mass.

In the double-sided adhesive sheet of the same aspect of the present invention, even if the formed adhesive layer is thinned, the high adhesive force can be fully exhibited, and the first adhesive layer and the second adhesive layer are preferred. At least one of the agent layers is a layer formed of an acrylic adhesive containing an acrylic resin, and more preferably is a layer formed of the acrylic adhesive for both the first adhesive layer and the second adhesive layer.

In addition, the acrylic adhesive is preferably an ultraviolet non-curable acrylic adhesive from the viewpoint of maintaining a sufficiently high adhesive force regardless of the environment even if the formed adhesive layer is thinned.

That is, the acrylic resin contained in the adhesive is preferably an ultraviolet non-curable acrylic resin.

As the acrylic adhesive used in the same aspect of the present invention, even if the formed adhesive layer is formed into a thin film, it can fully exhibit high adhesive force. As the acrylic resin, it is preferable to include An acrylic copolymer (A) having a structural unit (a1) of an alkyl (meth)acrylate having an alkyl group with a carbon number of 1-20 and a structural unit (a2) derived from a functional group-containing monomer.

In addition, the acrylic adhesive preferably contains a crosslinking agent (B) together with the acrylic copolymer (A), and may contain the above-mentioned adhesive additives within a range that does not impair the effects of the present invention.

Hereinafter, the acrylic copolymer (A) and the crosslinking agent (B) contained in the acrylic adhesive suitable as the adhesive for forming the first adhesive layer and the second adhesive layer will be described.

(Acrylic copolymer (A))

The acrylic copolymer (A) has a structural unit (a1) derived from an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms (hereinafter, also referred to as "monomer (a1')") and A structural unit (a2) derived from a functional group-containing monomer (hereinafter, also referred to as "monomer (a2')").

In addition, the acrylic copolymer (A) also has a structural unit (a3) derived from a monomer (a3') other than the monomers (a1') and (a1') together with the structural units (a1) and (a2).

The form of the copolymerization of the acrylic copolymer (A1) is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.

The acrylic copolymer (A) system may be used alone, or two or more of them may be used in combination.

However, the acrylic copolymer (A1) is preferably an ultraviolet non-curable acrylic copolymer having no polymerizable functional group.

The carbon number of the alkyl group of the monomer (a1′) is preferably 1-16, more preferably 1-12, still more preferably 4-8, and still more preferably 4-6.

Examples of the monomer (a1') system include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, Isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate Acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl ( Meth) acrylate and the like.

These monomers (a1') may be used alone, or two or more of them may be used in combination.

In the same aspect of the present invention, the monomer (a1') is preferably n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and more preferably n-butyl( Meth)acrylate.

The content of the structural unit (a1), relative to the total structural unit (100 mol%) of the acrylic copolymer (A), is preferably 50-98 mol%, more preferably 60-97 mol%, and still more Preferably, it is 70~96 mol%, and still more preferably is 80~93 mol%.

The monomer (a2') includes, for example, hydroxyl group-containing monomers, carboxyl group-containing monomers, epoxy group-containing monomers, amine group-containing monomers, cyano group-containing monomers, and ketone group-containing monomers. Monomers, monomers containing alkoxysilyl groups, etc.

These monomers (a2') may be used alone, or two or more of them may be used in combination.

In the same aspect of the present invention, the monomer (a2') is preferably a carboxyl group-containing monomer.

Examples of the carboxyl group-containing monomer include (meth)acrylic acid, succinic acid, maleic acid, fumaric acid, itaconic acid, and derivatives thereof, but preferably (meth)acrylic acid, succinic acid Acids and derivatives thereof are more preferably succinic acid mono(2-propenoxyethyl) ester and 2-carboxyethyl acrylate.

The content of the structural unit (a2), relative to the total structural unit (100 mol%) of the acrylic copolymer (A), is preferably 2-50 mol%, more preferably 3-40 mol%, and more Preferably it is 4~30 mol%, and even more preferably is 7-20 mol%.

In the same aspect of the present invention, the acrylic copolymer (A), as the structural unit (a2), preferably has a compound derived from mono(2-propenoxyethyl) succinate and 2-carboxyethyl acrylate Any structural unit (a2-1).

The content ratio of the structural unit (a2-1) in the structural unit (a2) is relative to the total amount (100 mol%) of the structural unit (a2), preferably 60-100 mol%, more preferably 70-100 Mole%, more preferably 80-100 mol%, still more preferably 90-100 mol%, particularly preferably 100 mol%.

In addition, the content of the structural unit (a2-1) is preferably 2 to 45 mol%, more preferably 3 to 35 mol% relative to the total structural unit (100 mol%) of the acrylic copolymer (A) %, more preferably 4-25 mol%, and still more preferably 7-20 mol%.

Examples of the monomer (a3') system include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentyl (meth)acrylate , Dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, imine (meth)acrylate and other (meth)acrylates with cyclic structure , Vinyl acetate, acrylonitrile, styrene, etc.

These monomers (a3') may be used alone, or two or more of them may be used in combination.

The content of the structural unit (a3), relative to the total structural unit (100% by mass) of the acrylic copolymer (A), is preferably 0-20 mol%, more preferably 0-10 mol%, and even better It is 0~5 mol%, and more preferably 0~1 mol%.

As the mass average molecular weight (Mw) of the acrylic copolymer (A), it is preferably 50,000 to 1.5 million, more preferably 150,000 to 1.3 million, still more preferably 250,000 to 1.1 million, and still more preferably 35 10,000~900,000.

The content of the acrylic copolymer (A) in the acrylic adhesive used in the same aspect of the present invention is preferably 50-100 mass relative to the total amount (100% by mass) of the effective ingredients of the acrylic adhesive %, more preferably 60~99.99% by mass, still more preferably 70~99.90% by mass, still more preferably 80~99.00% by mass, particularly preferably 90~ 98% by mass.

In addition, the acrylic adhesive used in the same aspect of the present invention may contain adhesive resins other than the acrylic copolymer (A).

However, the content of the adhesive resin other than the acrylic copolymer (A) is preferably 0-100 parts by mass relative to 100 parts by mass of the acrylic copolymer (A) contained in the acrylic adhesive, and more preferably It is 0-60 parts by mass, more preferably 0-30 parts by mass, still more preferably 0-15 parts by mass, particularly preferably 0-10 parts by mass.

(Crosslinking agent (B))

The acrylic adhesive used in the same aspect of the present invention preferably contains a crosslinking agent (B) together with the acrylic copolymer (A).

Examples of the crosslinking agent (B) series include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, amine-based crosslinking agents, and amine-based resins. Department of crosslinking agent and so on.

These crosslinking agents (B) may be used alone, or two or more of them may be used in combination.

In the aspect of the present invention, from the viewpoint that high adhesive force can be sufficiently exhibited even in a thin-filmed adhesive layer, as the crosslinking agent (B), it is preferable to include an isocyanate-based crosslinking agent.

The content of the crosslinking agent (B) in the acrylic adhesive used in the same aspect of the present invention is preferably 0.01-8 parts by mass, more preferably 0.05, relative to 100 parts by mass of the acrylic copolymer (A) ~5 parts by mass, more preferably 0.1~3 parts by mass.

<Peeling material>

The double-sided adhesive sheet of the same aspect of the present invention preferably has a structure in which a release material is further laminated on the surface of at least one of the first adhesive layer and the second adhesive layer.

In addition, the double-sided adhesive sheet of the present invention has a support containing polylactic acid. Therefore, in the case of a structure like the double-sided adhesive sheet 2 shown in Figure 1(b), it can effectively prevent the peeling material from being separated on one side. Separation of residual glue that may occur during removal.

Although there are no particular restrictions on the release material to be used, from the viewpoint of ease of handling, a release sheet in which a release agent is applied to a substrate is preferred. The release sheet may be one that coats a release agent on both sides of the substrate and conducts the release treatment, or one that coats the release agent on only one side of the substrate and conducts the release treatment.

Examples of substrates for release materials include paper substrates such as cellophane, coated paper, and coated paper; laminated papers formed by laminating thermoplastic resins such as polyethylene on these paper substrates; and, Polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and plastic films such as polyolefin films such as polypropylene or polyethylene.

Examples of release agents include rubber elastomers including olefin resins, isoprene resins, butadiene resins, etc., long-chain alkyl resins, alkyd resins, fluorine resins, and silicones. A release agent for resins such as resins.

In addition, the double-sided adhesive sheet 2 as shown in Figure 1(b) Generally, when two peeling materials 13a and 13b are used, the peeling materials 13a and 13b may be the same or different. However, it is preferable to adjust so that the difference between the peeling force of the peeling material 13a and the peeling material 13b is different, and to use a peeling material with a heavier peeling force (heavy peeling material), and the peeling force compared to the heavy peeling material. Two types of lighter release materials (light release materials).

In addition, when using a release material coated with a release agent on both sides and subjected to a release treatment, it is preferable to adjust the latter so that the difference in the peeling force of each surface of the release material is different.

Although the thickness of the release sheet can be appropriately selected without particular limitation, it is usually 10 to 200 μm, preferably 25 to 150 μm, and more preferably 35 to 80 μm.

[Method of manufacturing double-sided adhesive sheet]

The manufacturing method of the double-sided adhesive sheet of the present invention is not particularly limited.

For example, in the case of the double-sided adhesive sheet 1 in Figure 1(a), an adhesive can be applied to one of the support 11 and dried to form the first adhesive layer 12a, and then on the support 11 On the other surface, the adhesive is applied in the same manner and dried to form the second adhesive layer 12b.

In addition, if it is the double-sided adhesive sheet 2 in Figure 1 (b), it can be produced according to the following procedures (ia) to (iiia).

(ia) Apply an adhesive on the surface of the peeling material 13a that has been subjected to the peeling treatment, and dry it to form the first adhesive layer 12a, which is then laminated to the support Body 11, and make a single-sided adhesive sheet.

(iia) On the surface of the separately prepared release material 13b subjected to the release treatment, an adhesive is similarly applied and dried to form the second adhesive layer 12b.

(iiia) The surface of the support 11 of the single-sided adhesive sheet produced in the above (ia) and the exposed surface of the second adhesive layer 12b formed in the above (iia) are respectively bonded to obtain a double-sided adhesive sheet 2 .

In addition, as a method of manufacturing the double-sided adhesive sheet 2 in Figure 1 (b), it can also be manufactured in accordance with the following procedures (ib) to (iiib).

(ib) An adhesive is applied to the surface of the peeling material 13a that has been subjected to the peeling treatment, and dried to form the first adhesive layer 12a.

(iib) The surface of the separately prepared release material 13b subjected to the release treatment is coated with an adhesive in the same manner and dried to form the second adhesive layer 12b.

(iiib) The exposed surface of the first adhesive layer 12a and the exposed surface of the second adhesive layer 12b are respectively attached to both sides of the support 11 to obtain a double-sided adhesive sheet 2.

In the above-mentioned double-sided adhesive sheet manufacturing method, since the thickness of the supporting body 11 used is very thin, in order to improve the operability of the supporting body 11, an application sheet can also be used.

In this specification, "applied sheet" means a sheet attached to support the core material or adhesive sheet in order to improve the handling of a very thin core material or adhesive sheet that is difficult to transport or attach.

In the above-mentioned two-sided adhesive sheet manufacturing process, the application sheet can also be directly laminated on the support 11 to bond with the adhesive layer, and then the application sheet is peeled off, and the surface of the support 11 after peeling , Attach another adhesive layer to make two-sided adhesive sheets.

In addition, it is preferable that when the adhesive is applied to the support or release material, in order to easily form a thin adhesive layer, as described above, the adhesive is diluted with an organic solvent to prepare a solution of the adhesive form.

Examples of methods for applying the adhesive on the support or release material include spin coating, spray coating, bar coating, knife coating, roll coating, knife coating, and die coating. , Gravure coating method and other well-known methods.

Preferably, in order to prevent solvent or low-boiling components from remaining, and cross-linking (reaction) with a cross-linking agent blended to exhibit adhesiveness, it is formed by coating an adhesive on the support or release material. After coating the film, heat treatment is performed.

The temperature condition of the heat treatment is preferably 70 to 150°C, more preferably 80 to 120°C. The treatment time of the heat treatment is preferably 30 seconds to 5 minutes, more preferably 40 to 180 seconds.

[Physical Properties of Adhesive Sheets on Both Sides]

The double-sided adhesive sheet of the present invention can exhibit sufficiently high adhesive force even if it is made into a thin film, and the effect of inhibiting the separation of residual glue is excellent.

Adhesive sheets on both sides of the same state of the present invention, as in Under 23℃, 50%RH (relative humidity) environment, after sticking to stainless steel plate (SUS304 steel plate, 120 grinded) and after 24 hours, the adhesive force measured according to JIS Z0237:2000, preferably 1.5N/ 25mm or more, more preferably 2.0N/25mm or more, still more preferably 2.5N/25mm or more, still more preferably 3.0N/25mm or more, particularly preferably 4.5N/25mm or more.

In addition, in this specification, the said adhesive force means the value measured based on JISZ0237:2000, Specifically, it means the value measured by the method and conditions described in the Example mentioned later.

[Example]

The various physical property values shown in the description of the examples below are the values measured as follows.

(1) Mass average molecular weight (Mw)

Measure with the following equipment and conditions, and calculate the value obtained by standard polystyrene conversion.

Device name: "HLC-8220GPC" (manufactured by TOSOH Co., Ltd.)

Column: Connected in sequence "TSKgelGMHXL", "TSKgelGMHXL", and "TSKgel2000HXL" (all manufactured by TOSOH Co., Ltd.)

Developing solvent: tetrahydrofuran

Injection volume: 80μl

Measuring temperature: 40℃

Flow rate: 1.0mL/min

Detector: Differential refractometer

(2) Thickness measurement

The thickness and total thickness of each layer of the double-sided adhesive sheet were measured with a reflective film thickness meter (manufactured by Filmetrics Co., Ltd., product name "F20").

Specifically, the above-mentioned reflection type film thickness meter was used to measure the film thickness of any 7 locations cut into a 10mm×100mm double-sided adhesive sheet, and calculate the measured film thickness values of the 7 locations to remove the maximum and minimum values. The average value of the film thickness values of the 5 parts of the value, and the average value is used as the thickness or total thickness of each layer of the adhesive sheet on both sides of the measurement object.

(3) Membrane strength of the support

It is measured in accordance with JIS Z 1707 (1997).

Specifically, using a creep meter (CREEP METER; RE2-33005B made by Yamaden Co., Ltd.), a semicircular needle with a diameter of 1.0 mm and a tip shape radius of 0.5 mm at a speed of 30 mm/min is used to measure The surface of the support of the object was pierced vertically, and the maximum stress exhibited until the needle penetrated was defined as the film strength (mN). In addition, measurement conditions other than these are based on JIS Z1707 (1997).

For the target support, the above-mentioned measurement was performed three times to calculate the film strength, and the average value of the three times was used as the film strength of the support.

Manufacturing example 1

(Production of PLA film)

Make polylactic acid resin (manufactured by PURAC, product name "PURASORB(R)PDL20", copolymer of L-lactic acid and D-lactic acid, [L-lactic acid]/[D-lactic acid]=50/50 (mole ratio) ) Is dissolved in ethanol to prepare a polylactic acid ethanol solution with a resin content of 5% by mass.

Next, as an application sheet, a polyolefin-based film (manufactured by ZEON Co., Ltd., product name "ZEONOR", thickness 50μm) was prepared, and the application sheet was coated so as to have a specific thickness after drying. The polylactic acid ethanol solution was dried at 100°C for 2 minutes to produce a polylactic acid film laminated on the application sheet.

In addition, polylactic acid films were produced with thicknesses of 0.2 μm, 0.5 μm, 0.7 μm, 1.0 μm, and 2.0 μm, respectively.

The details of the supports and adhesives used in the examples and comparative examples are shown below.

<Support body>

‧PLA film (0.2):

The polylactic acid film (film strength = 40 mN) with a thickness of 0.2 μm produced in Production Example 1.

‧PLA film (0.5):

A polylactic acid film (film strength=45 mN) with a thickness of 0.5 μm produced in Production Example 1.

‧PLA film (0.7):

The polylactic acid film (film strength=97 mN) with a thickness of 0.7 μm produced in Production Example 1.

‧PLA film (1.0):

The polylactic acid film (film strength = 230 mN) with a thickness of 1.0 μm produced in Production Example 1.

‧PLA film (2.0):

A polylactic acid film (film strength=480 mN) with a thickness of 2.0 μm produced in Production Example 1.

‧PET film (0.5):

A polyethylene terephthalate (PET) film with a thickness of 0.5 μm (film strength = 180 mN).

‧PET film (6.0):

A PET film with a thickness of 6.0 μm (film strength = 2040 mN).

‧Polyurethane film (6.0):

Except for changing the thickness from 2 μm to 6.0 μm, a polyurethane film with a thickness of 6.0 μm (film strength=1540 mN) was produced according to the description of Production Example 4 in the paragraph of Patent Document 2.

<Adhesive>

‧Adhesive (1):

Acrylic copolymer (BA/2AOE=90/10 (mole ratio), Mw) polymerized by n-butyl acrylate (BA) and succinic acid mono(2-propenoxyethyl) ester (2AOE) =280,000) 100 parts by mass (parts by mass of solid content), and isocyanate-based crosslinking agent (TOSOH shares Co., Ltd., product name "CORONATE L") 0.45 parts by mass (parts by mass of solid content), mixed and diluted with ethyl acetate, is a solution of acrylic adhesive with a solid content concentration of 13% by mass.

‧Adhesive (2):

Acrylic copolymer (BA/AAc=96/4 (mole ratio), Mw=1 million) made by polymerizing n-butyl acrylate (BA) and acrylic acid (AAc) to 100 parts by mass (parts by mass of solid content) ), tackifying resin (Harima Chemicals Co., Ltd., product name "HARIESTER TF") 50 parts by mass (solid content), and isocyanate-based crosslinking agent (TOSOH Co., Ltd. product name "CORONATE L") 0.1 parts by mass (parts by mass of solid content), mixed and diluted with ethyl acetate, is a solution of acrylic adhesive with a solid content concentration of 13% by mass.

‧Adhesive (3):

Acrylic copolymer (BA/2EHA) polymerized by n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), acrylic acid (AAc), and 4-hydroxybutyl acrylate (4HBA) /AAc/4HBA=70/30/3/0.05 (mass ratio), Mw=440,000) 100 parts by mass (parts by mass of solid content), tackifying resin (manufactured by Arakawa Chemical Industry Co., Ltd., product name "PENSEL D125" ) 30 parts by mass (parts by mass of solid content) and 2 parts by mass (parts by mass of solid content) of an isocyanate-based crosslinking agent (manufactured by TOSOH Co., Ltd., product name "CORONATE L"), and diluted with ethyl acetate Acrylic adhesive with a solid content of 13% by mass liquid.

Examples 1~6, Comparative Examples 2~5

On the release-treated surface of a heavy release sheet (manufactured by LINTEC Co., Ltd., product name "SP-PET381031", a PET film with a thickness of 38μm after release treatment with a silicone-based release agent), apply the types shown in Table 1 The adhesive was dried at 100°C for 1 minute to form the first adhesive layer with the thickness shown in Table 1.

Next, a support of the type shown in Table 1 was bonded to the surface of the exposed first adhesive layer to obtain a single-sided adhesive sheet.

In addition, in the case of using various PLA films as a support, in order to maintain the operability, the surface of the PLA film on the side of the non-laminated application sheet is left with the laminated application sheet on the PLA film. The first adhesive layer is attached, and after that, the applied sheet is removed to obtain a single-sided adhesive sheet.

In addition, prepare a light release sheet (product name "SP-PET381130" by LINTEC Co., Ltd., product name "SP-PET381130", a PET film with a thickness of 38 μm after peeling treatment with a silicone-based release agent) on the peeling treatment surface, and apply it with the first Adhesives of the same type used in the formation of the adhesive layer were dried at 100°C for 1 minute, and the second adhesive layer with the thickness shown in Table 1 was formed.

Next, the surface of the support side of the above-mentioned single-piece adhesive sheet and the surface of the second adhesive layer were respectively bonded to produce a re-peelable sheet, the first adhesive layer, the support, and the second adhesive layer. Adhesive layer, light peeling and thin Sheets (P) are adhered to both sides of the structure of the sheet.

Also, in the production process of the double-sided adhesive sheet (P), the above-mentioned "heavy peeling sheet" was replaced with a "light peeling sheet" (manufactured by LINTEC Co., Ltd., product name "SP-PET381130"), except that A double-sided adhesive sheet (Q) with a structure in which a light release sheet, a first adhesive layer, a support, a second adhesive layer, and a light release layer are sequentially laminated is produced together.

Comparative example 1

The adhesive (1) was coated on the release-treated surface of a heavy release sheet (manufactured by LINTEC Co., Ltd., product name "SP-PET381031"), and dried at 100°C for 1 minute to form an adhesive layer with a thickness of 2 μm.

Then, a light release sheet (manufactured by LINTEC Co., Ltd., product name "SP-PET381130") is laminated on the exposed surface of the formed adhesive layer, and a heavy release sheet, an adhesive layer, and a light release sheet are laminated in sequence. The structure of the peeling sheet is bonded with sheets (P') on both sides.

In addition, in the production process of the double-sided adhesive sheet (P'), the above-mentioned "heavy peeling sheet" was replaced with a "light peeling sheet" (manufactured by LINTEC Co., Ltd., product name "SP-PET381130"). In addition, In the same way, a double-sided adhesive sheet (Q) with a structure in which a light release sheet, a first adhesive layer, a support, a second adhesive layer, and a light release sheet are sequentially laminated is produced.

Adhesive sheets made on both sides using the examples and comparative examples (P) or (P') and double-sided adhesive sheet (Q), perform the following evaluation. The results of these are shown in Table 1.

(Assessment 1) Adhesion measurement

For the "double-sided adhesive sheet (P) or (P')" produced in the examples and comparative examples, peel off the lightly peelable sheet, and stick a 25μm-thick polyester film on the surface of the exposed adhesive layer, and then cut it The test piece was made into a size of 25mm×300mm.

Next, in an environment of 23°C and 50%RH (relative humidity), the heavy peeling sheet of the test piece was peeled off, and the exposed surface of the adhesive layer was attached to a stainless steel plate (SUS304 steel plate, No. 120 grinding), stand for 24 hours in the same environment.

Next, in accordance with JIS Z0237:2000, the 180° tear method was used to measure the adhesive force after 24 hours of attachment in the same environment at a tensile speed of 300 mm/min.

(Evaluation 2) Residual glue separation test

Regarding the "Double-sided Adhesive Sheet (Q)" produced in the Examples and Comparative Examples, when one of the light-peelable sheets was peeled off, the residual glue separation at the interface between the light-peel sheet and the adhesive layer was performed 20 times. For confirmation, use the following benchmarks for evaluation.

A: No glue residue occurred in all the 20 confirmed times.

B: Residual glue separation occurred once out of the 20 confirmed times.

C: Separation of residual glue occurred more than 2 times out of the 20 confirmed times.

According to Table 1, it is known that although the double-sided adhesive sheets produced in Examples 1 to 6 thin the adhesive layer, the residual glue separation phenomenon is not easy to occur, and it has excellent adhesion.

On the other hand, the double-sided adhesive sheet produced in Comparative Example 1 resulted in a high frequency of the occurrence of residual glue separation. In addition, the double-sided adhesive sheets produced in Comparative Examples 2 to 5 can suppress the occurrence of residual glue separation, but with the thinning of the adhesive layer, compared with the double-sided adhesive sheets produced in the examples, it cannot be obtained. Full adhesion.

[Industrial availability]

The double-sided adhesive sheet of the present invention can exhibit sufficiently high adhesive force even if it is made into a thin film, and the effect of inhibiting the separation of residual glue is excellent.

Therefore, the double-sided adhesive sheet of the present invention, for example, in portable electronic equipment or optical equipment that requires thinning, is suitable for joining two members at a location with a narrow gap, or for temporary bonding during processing, etc. in.

1, 2‧‧‧ Adhesive sheets on both sides

11‧‧‧Support

12a‧‧‧The first adhesive layer

12b‧‧‧Second adhesive layer

13a、13b‧‧‧Striping material

Claims (7)

A double-sided adhesive sheet, which is a double-sided adhesive sheet with a first adhesive layer and a second adhesive layer on both sides of a support, wherein the support includes polylactic acid, and the thickness of the support is 1.5 μm or less, relatively The total thickness of the first adhesive layer and the second adhesive layer is 100, and the ratio of the thickness of the aforementioned support is 5.0-70.0. Such as the two-sided adhesive sheet of claim 1, wherein the film strength of the aforementioned support is 1~300mN. Such as the double-sided adhesive sheet of claim 1 or 2, wherein the content of the aforementioned polylactic acid is 70-100% by mass relative to the total mass of the aforementioned support. The double-sided adhesive sheet of claim 1 or 2, wherein at least one of the first adhesive layer and the second adhesive layer is a layer formed of an acrylic adhesive containing an acrylic resin. Such as the double-sided adhesive sheet of claim 1 or 2, wherein the individual thickness of the first adhesive layer and the second adhesive layer are independently 0.5 to 3.0 μm. Such as the two-sided adhesive sheet of claim 1 or 2, wherein the total thickness of the two-sided adhesive sheet when attached to two adherends via the two-sided adhesive sheet is 6.0 μm or less. For example, the two-sided adhesive sheet of claim 1 or 2, which is attached to a stainless steel plate (SUS304 steel plate, 120 grinded) under an environment of 23°C and 50%RH (relative humidity) and after 24 hours according to JIS Z0237: 2000 The measured adhesion force is above 1.5N/25mm.

Images