JPWO2017170446A1 - Double-sided adhesive sheet - Google Patents

Abstract

A double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of a support, respectively, wherein the support contains polylactic acid, and the thickness of the support is 1.5 μm A double-sided pressure-sensitive adhesive sheet is provided as follows. Even if the double-sided pressure-sensitive adhesive sheet is made thin, the double-sided pressure-sensitive adhesive sheet can exhibit a sufficiently high adhesive force and is excellent in the effect of suppressing the tearing phenomenon.

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive strength of the pressure-sensitive adhesive sheet depends on the composition of the pressure-sensitive adhesive and the polarity, as well as the amount of pressure-sensitive adhesive applied on the support, that is, the thickness of the pressure-sensitive adhesive layer to be formed. That is, as the pressure-sensitive adhesive sheet generally has a thicker pressure-sensitive adhesive layer, the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet becomes higher.
The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet such as a label or tape is appropriately set according to the application of the pressure-sensitive adhesive sheet. However, since there is a concern about a decrease in pressure-sensitive adhesive force, the thickness is less than 10 μm. Not.
However, in recent years, it has been desired to reduce the thickness of electronic devices and optical devices, etc. For adhesive sheets used for bonding of members of such electronic devices and optical devices, or temporary bonding during processing, etc. Is required to have a high adhesive strength while being thinned.

Various pressure-sensitive adhesive sheets have been proposed to meet such demands.
For example, Patent Document 1 has an adhesive layer on both surfaces of a support such as a polyethylene terephthalate (PET) film having a thickness of 0.002 to 0.012 mm, and a total thickness of 0.003 mm to 0.03 mm. A double-sided adhesive tape is disclosed that has a break strength of 2 to 26 MPa / 10 mm width.

JP 2005-105212 A

By the way, there are cases where two members included in a thinned electronic device or optical device are joined via a double-sided PSA sheet. In order to meet the demand for thin film devices, the clearance between two members to be joined is often narrow. Therefore, further thinning is required for the double-sided PSA sheet used for bonding.
As means for meeting the demand for further thinning of the double-sided pressure-sensitive adhesive sheet, it is conceivable to reduce the thickness of each layer such as a pressure-sensitive adhesive layer and a support constituting the double-sided pressure-sensitive adhesive sheet.
However, when the pressure-sensitive adhesive layer is further thinned, there is a concern that the adhesive force is reduced and the joining of the two members becomes insufficient.
On the other hand, the thinning of the support is limited in terms of production and strength of the support. For example, in the double-sided adhesive sheet described in Patent Document 1, it is extremely difficult to make the thickness of the PET film used as the support less than 2 μm from the viewpoint of molding.

In addition, as a means for thinning the double-sided pressure-sensitive adhesive sheet, a double-sided pressure-sensitive adhesive sheet having a structure in which the support layer (core material) is not provided and the pressure-sensitive adhesive layer is sandwiched between two release materials is used. A method for reducing the thickness is also conceivable.
However, if the support (core material) is omitted, when one of the two release materials is peeled off, the pressure-sensitive adhesive layer does not peel off at a predetermined interface where the release material should be peeled off, and the adhesive layer cohesively breaks down. In addition, a “crying separation phenomenon” in which a part of the pressure-sensitive adhesive layer remains on both of the release materials tends to occur.
In Patent Document 1, there is no examination for further reducing the film thickness while maintaining the adhesive force of the double-sided adhesive sheet and for avoiding the “crying separation phenomenon” associated with the thinner adhesive layer.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a double-sided pressure-sensitive adhesive sheet that can exhibit a sufficiently high adhesive force even if it is thinned, and is excellent in the effect of suppressing the tearing phenomenon. And

In the double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of the support, the present inventors use the support containing polylactic acid and adjust the thickness of the support to a predetermined value or less, thereby I found that it could be solved.
That is, the present invention provides the following [1] to [8].
[1] A double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of a support,
The support comprises polylactic acid, and the support has a thickness of 1.5 μm or less;
Double-sided adhesive sheet.
[2] The double-sided pressure-sensitive adhesive sheet according to the above [1], wherein the support has a film strength of 1 to 300 mN.
[3] The double-sided pressure-sensitive adhesive sheet according to the above [1] or [2], wherein the content of the polylactic acid is 70 to 100% by mass with respect to the total mass of the support.
[4] Any one of the above [1] to [3], wherein at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is a layer formed from an acrylic pressure-sensitive adhesive containing an acrylic resin. The double-sided pressure-sensitive adhesive sheet according to item.
[5] Any one of the above-mentioned [1] to [4], wherein the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are each independently 0.5 to 3.0 μm. Double-sided pressure-sensitive adhesive sheet as described in 1.
[6] The above [1] to [5], wherein the ratio of the thickness of the support to the total thickness 100 of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 5.0 to 70.0. ] The double-sided adhesive sheet as described in any one of.
[7] In any one of the above [1] to [6], the total thickness of the double-sided pressure-sensitive adhesive sheet when pasted on two adherends via the double-sided pressure-sensitive adhesive sheet is 6.0 μm or less. The double-sided pressure-sensitive adhesive sheet described.
[8] Adhesive strength measured according to JIS Z0237: 2000 after 24 hours from pasting on a stainless steel plate (SUS304 steel plate, No. 120 polishing) in an environment of 23 ° C. and 50% RH (relative humidity) The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [7], which is 1.5 N / 25 mm or more.

  Even if the double-sided pressure-sensitive adhesive sheet of the present invention is thinned, the double-sided pressure-sensitive adhesive sheet can exhibit a sufficiently high adhesive force and is excellent in the effect of suppressing the tearing phenomenon.

It is sectional drawing of the said double-sided adhesive sheet which shows the structure of the double-sided adhesive sheet of 1 aspect of this invention.

In this specification, the thickness of each layer constituting the double-sided pressure-sensitive adhesive sheet and the total thickness of the double-sided pressure-sensitive adhesive sheet are values measured by spectroscopic analysis of reflected light, specifically based on the method described in the examples. Means the measured value.
In this specification, the value of the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and specifically measured based on the method described in the examples. Means the value.
In this specification, for example, “(meth) acrylate” refers to both acrylate and methacrylate, and the same applies to other similar terms.

[Configuration of double-sided adhesive sheet]
The double-sided pressure-sensitive adhesive sheet of the present invention is particularly limited as long as it has a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer (hereinafter collectively referred to as “pressure-sensitive adhesive layer”) on both sides of the support, respectively. Not.
FIG. 1 is a cross-sectional view of the double-sided pressure-sensitive adhesive sheet showing the configuration of the double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention.

As a double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention, for example, as shown in FIG. 1A, a first pressure-sensitive adhesive layer 12a and a second pressure-sensitive adhesive layer 12b are directly laminated on both surfaces of a support 11, respectively. The double-sided pressure-sensitive adhesive sheet 1 having the above-described configuration is exemplified.
Also, from the viewpoint of handleability, as shown in FIG. 1B, double-sided pressure-sensitive adhesive in which release materials 13a and 13b are further laminated on the surfaces of the first pressure-sensitive adhesive layer 12a and the second pressure-sensitive adhesive layer 12b, respectively. The sheet 2 may be used.
Moreover, as a double-sided adhesive sheet of 1 aspect of this invention, the peeling material by which the peeling process was given to both surfaces was laminated | stacked on the surface of either the 1st adhesive layer 12a and the 2nd adhesive layer 12b. Moreover, the double-sided adhesive sheet which has the structure wound by roll shape may be sufficient.
That is, the double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention may have a configuration in which a release material is further laminated on one or both surfaces of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.

As the total thickness of the double-sided pressure-sensitive adhesive sheet when affixed to two adherends via the double-sided pressure-sensitive adhesive sheet of the present invention, from the viewpoint of a double-sided pressure-sensitive adhesive sheet that can also be used for joining two sites where the clearance is narrow, 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, and particularly preferably 3.0 μm or less.
Even if the double-sided pressure-sensitive adhesive sheet of the present invention is made as thin as 6.0 μm or less, the double-sided pressure-sensitive adhesive sheet can exhibit a sufficiently high adhesive force, and can effectively suppress the tearing phenomenon.
On the other hand, from the viewpoint of producing a double-sided pressure-sensitive adhesive sheet that exhibits excellent adhesive strength and can effectively suppress the crying separation phenomenon, the double-sided pressure-sensitive adhesive when being applied to two adherends via the double-sided pressure-sensitive adhesive sheet of the present invention. The total thickness of the sheet is preferably 1.5 μm or more, more preferably 1.7 μm or more, and further preferably 2.0 μm or more.

  In the present specification, the “thinned double-sided pressure-sensitive adhesive sheet” means that the total thickness of the double-sided pressure-sensitive adhesive sheet when adhered to two adherends via the double-sided pressure-sensitive adhesive sheet is adjusted to 6.0 μm or less. It means a double-sided pressure-sensitive adhesive sheet.

Further, in this specification, “the total thickness of the double-sided pressure-sensitive adhesive sheet when affixed to two adherends via a double-sided pressure-sensitive adhesive sheet” means the layer of a release material or the like removed when affixed to the adherend The thickness of the double-sided pressure-sensitive adhesive sheet excluding the thickness means, for example, the thickness indicated by “Z1” in the double-sided pressure-sensitive adhesive sheet 1 shown in FIG. 1 and “Z2” in the double-sided pressure-sensitive adhesive sheet 2.
That is, the “total thickness of the double-sided pressure-sensitive adhesive sheet when pasted on two adherends via a double-sided pressure-sensitive adhesive sheet” is the thickness of the release materials 13a and 13b of the double-sided pressure-sensitive adhesive sheet 2 shown in FIG. Is included, but includes, for example, the thicknesses of layers other than the support and the pressure-sensitive adhesive layer that are not removed even when applied to an adherend.
Examples of the layers other than the support and the pressure-sensitive adhesive layer that are not removed even when being attached to the adherend include a primer layer, an antistatic layer, an ultraviolet absorbing layer, and the like. It is preferable to be provided between the first adhesive layer or the second adhesive layer.

In the double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention, the ratio of the thickness of the support to the total thickness 100 of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 5.0 to 70.0, More preferably, it is 5.2-50.0, More preferably, it is 5.5-40.0, More preferably, it is 6.0-30.0, Most preferably, it is 6.2-20.0.
If the said ratio is in the said range, while producing the outstanding adhesive force, it can be set as the double-sided adhesive sheet which can suppress a tearing phenomenon effectively. Moreover, the tearing of the double-sided adhesive sheet which is easy to occur at the time of sticking or peeling can be suppressed.

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

<Support>
The support which the double-sided pressure-sensitive adhesive sheet of the present invention has includes a polylactic acid and has a thickness of 1.5 μm or less.
A general-purpose resin such as polyethylene terephthalate (PET) or polyurethane, which is a constituent resin of a support used for general pressure-sensitive adhesive sheets, is difficult to be molded as thin as 1.5 μm or less by a normal molding method. .
Further, even if a support having 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, the effect of improving the adhesive strength is not exhibited by using the support. .

On the other hand, since the support containing polylactic acid has high self-supporting property, it can be molded as thin as 1.5 μm or less.
In addition, the present inventors have found that a double-sided pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on both sides of a support containing polylactic acid has a very high effect of improving the adhesive strength, and particularly exhibits high adhesive strength even when it is made thin. The double-sided pressure-sensitive adhesive sheet according to the present invention has been completed based on the findings.
In particular, the support containing polylactic acid has high self-supporting property and moderate flexibility even when the thickness is reduced to 1.5 μm or less.
Therefore, the double-sided pressure-sensitive adhesive sheet provided with a thinned pressure-sensitive adhesive layer on both sides of the support has excellent followability with respect to the surface of the adherend when applied to the adherend, and the pressure-sensitive adhesive layer is made thin. However, it is considered that excellent adhesive strength is expressed.

Furthermore, in the double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on both sides of a general PET film or the like, the two pressure-sensitive adhesive layers are divided by the support, and depending on the flexibility of one pressure-sensitive adhesive layer, the other It is unlikely that the adhesive strength of the adhesive layer will change.
That is, the adhesive strength of each pressure-sensitive adhesive layer basically depends only on the configuration and characteristics of each pressure-sensitive adhesive layer, and the influence received by the configuration and characteristics of the other pressure-sensitive adhesive layer is extremely small.
On the other hand, in the double-sided PSA sheet of the present invention, the support containing polylactic acid is thinned to 1.5 μm or less. For example, depending on the properties such as flexibility of one PSA layer, Thus, it is possible to contribute to the improvement of the adhesive strength of the other pressure-sensitive adhesive layer.
As a result, the double-sided PSA sheet of the present invention is considered to exhibit excellent adhesive strength on both sides even when it is thinned.
Moreover, since the double-sided adhesive sheet of this invention has a support body as a structure, it can suppress a tearing phenomenon effectively.

The thickness of the support used in the present invention is 1.5 μm or less, 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. Hereinafter, it is particularly preferably 0.4 μm or less.
Since the double-sided PSA sheet using a support having a thickness exceeding 1.5 μm is hard, the followability with respect to the surface of the adherend is lowered, and as a result, the adhesive force is easily lowered.
The thickness of the support is not limited to a lower limit, but the viewpoint of making a double-sided pressure-sensitive adhesive sheet that can effectively suppress the tearing phenomenon, and the breakage of the double-sided pressure-sensitive adhesive sheet that can occur at the time of sticking or peeling are suppressed. From the viewpoint, 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 has a structural unit other than the structural unit (1). May be.

In addition, the structural unit (1) may be a structural unit derived from L-lactic acid or a structural unit derived from D-lactic acid.
That is, the polylactic acid may be poly-L-lactic acid, which is a homopolymer of L-lactic acid, or poly-D-lactic acid, which is a homopolymer of D-lactic acid. It may be a copolymer with D-lactic acid.
Among these, the polylactic acid is preferably a copolymer of L-lactic acid and D-lactic acid.

When a copolymer of L-lactic acid and D-lactic acid is used, the molar ratio of the structural unit derived from L-lactic acid and the structural unit derived from D-lactic acid in the copolymer ([L-lactic acid] / [D-lactic acid]) is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, still more preferably 30/70 to 70/30, still more preferably 40/60 to 60/40.
By setting the molar ratio as the copolymer within the above range, the crystallinity can be appropriately maintained, and the support including the copolymer can be adjusted to have an appropriate hardness. . As a result, when the obtained pressure-sensitive adhesive sheet is affixed to the adherend, excellent followability with respect to the surface of the adherend is obtained, and excellent adhesive strength is easily exhibited.

  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 one embodiment of the present invention may contain a resin, an additive, or the like other than polylactic acid as long as the effects of the present invention are not impaired.
Examples of resins other than polylactic acid that can be included in the support include, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, urethane resins such as urethane acrylate, polyethylene resins, polypropylene resins, and polyvinyl chloride. Resin, polyvinylidene chloride resin, polyvinyl alcohol resin, ethylene-vinyl acetate copolymer, polystyrene resin, polycarbonate resin, acrylic resin, norbornene resin, cycloolefin resin and the like.

  Examples of the additive that can be contained in the support include an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, and a colorant.

The support used in one embodiment of the present invention only needs to contain polylactic acid. For example, not only a support formed by molding a resin composition containing polylactic acid, but also a resin other than polylactic acid, papers, Or the support body etc. which laminated the support body which consists of metal foils, such as aluminum and copper, with the resin composition containing polylactic acid may be sufficient.
However, from the viewpoint of manufacturing a support having a thickness of 1.5 μm or less, the support used in one embodiment of the present invention is a single-layer support formed by molding a resin composition containing polylactic acid. preferable.
Moreover, the resin composition may contain resin components other than polylactic acid and various additives as long as the effects of the present invention are not impaired.

  The content of polylactic acid contained in the support used in one embodiment of the present invention is such that the double-sided pressure-sensitive adhesive sheet can exhibit sufficiently high adhesive strength even if it is thinned, and the support is 1.5 μm or less in thickness. From the viewpoint of manufacturing, preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and still more preferably, with respect to the total mass (100% by mass) of the support. Is 95 to 100% by mass.

  In particular, the content of the copolymer of L-lactic acid and D-lactic acid contained in the support used in one embodiment of the present invention is preferably 60 with respect to the total mass (100% by mass) of the support. It is -100 mass%, More preferably, it is 70-100 mass%, More preferably, it is 80-100 mass%, More preferably, it is 90-100 mass%, Most preferably, it is 95-100 mass%.

The film strength of the support used in one embodiment of the present invention is preferably 1 to 300 mN, more preferably 3 to 250 mN, from the viewpoint of making a double-sided PSA sheet that can exhibit sufficiently high adhesive strength even when thinned. Preferably it is 5-200 mN, More preferably, it is 10-130 mN, Most preferably, it is 15-90 mN.
If the film strength of the support is within the above range, even when the double-sided pressure-sensitive adhesive sheet is provided with a thinned pressure-sensitive adhesive layer on both sides of the support, Excellent followability, and excellent adhesive strength is easily expressed.
In addition, in this specification, the film | membrane intensity | strength of a support body is the value measured based on JISZ1707 (1997), Comprising: Specifically, the value measured based on the method and conditions as described in an Example. Means.

<First pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer>
The double-sided pressure-sensitive adhesive sheet of the present invention has a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of the support, respectively.
The thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are each independently preferably 0.5 to 3.0 μm, more preferably 0.7 to 2.0 μm, and still more preferably 0. .8 to 1.8 μm, more preferably 0.9 to 1.6 μm.
Since the double-sided pressure-sensitive adhesive sheet of the present invention contains polylactic acid and has a support having a thickness of 1.5 μm or less, it is sufficiently high even if the thickness of each pressure-sensitive adhesive layer is reduced to 3.0 μm or less. It can be set as the double-sided adhesive sheet which can express adhesive force.

  Further, the total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 1.0 to 6.0 μm, more preferably 1.4 to 4.0 μm, and still more preferably 1.6. It is -3.6 micrometers, More preferably, it is 1.8-3.2 micrometers.

The pressure-sensitive adhesive which is a material for forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is not particularly limited as long as it can exhibit sufficiently high adhesive force even if the pressure-sensitive adhesive layer is thinned. For example, an adhesive containing at least one adhesive resin selected from acrylic resins, urethane resins, rubber resins, silicone resins, vinyl ether resins, polyester resins, and polyolefin resins can be used.
However, from the viewpoint of maintaining a sufficiently high adhesive strength regardless of the environment, the adhesive resin is preferably an ultraviolet non-curable resin.
In the present specification, the ultraviolet non-curable resin means a resin having no polymerizable functional group that can be polymerized by irradiation with ultraviolet rays.

In addition, the pressure-sensitive adhesive is within a range not impairing the effects of the present invention, for example, a crosslinking agent, a tackifier, an ultraviolet absorber, an antioxidant, an antiseptic, a fungicide, a plasticizer, an antifoaming agent, and a wettability. You may contain additives for adhesives, such as a regulator.
However, from the viewpoint of maintaining a sufficiently high adhesive strength regardless of the environment, the pressure-sensitive adhesive is preferably as low as possible in the content of the oligomer component having a polymerizable functional group.
The content of the oligomer component having a polymerizable functional group is preferably less than 5 parts by mass, more preferably less than 1 part by mass, and still more preferably 0.01 parts by mass with respect to 100 parts by mass of the adhesive resin contained in the adhesive. Less than 0.001, more preferably less than 0.001 parts by weight.

The pressure-sensitive adhesive layer is formed by applying a pressure-sensitive adhesive to a support or a release material. In order to facilitate the formation of a thin pressure-sensitive adhesive layer, the pressure-sensitive adhesive is diluted with an organic solvent, It is good also as a solution of.
Examples of the organic solvent include toluene, ethyl acetate, methyl ethyl ketone, and the like, but the organic solvent used in the synthesis of the resin contained in the pressure-sensitive adhesive layer may be used as it is.
As solid content concentration of the solution of an adhesive, Preferably it is 5-60 mass%, More preferably, it is 10-40 mass%.

In the double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are formed from the viewpoint of exhibiting sufficiently high adhesive force even if the pressure-sensitive adhesive layer to be formed is thinned. It is preferable that at least one is a layer formed from an acrylic pressure-sensitive adhesive containing an acrylic resin, and both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are formed from the acrylic pressure-sensitive adhesive. More preferably, it is a layer.
The acrylic pressure-sensitive adhesive is an ultraviolet non-curable acrylic pressure-sensitive adhesive from the viewpoint of maintaining a sufficiently high adhesive force regardless of the environment even if the pressure-sensitive adhesive layer to be formed is thinned. preferable.
That is, the acrylic resin contained in the adhesive is preferably an ultraviolet non-curable acrylic resin.

As an acrylic adhesive used in one embodiment of the present invention, an acrylic resin having 1 to 20 carbon atoms is used as an acrylic resin from the viewpoint of exhibiting a sufficiently high adhesive force even if the adhesive layer to be formed is thinned. It is preferable to include an acrylic copolymer (A) having a structural unit (a1) derived from an alkyl (meth) acrylate having an alkyl group and a structural unit (a2) derived from a functional group-containing monomer.
The acrylic pressure-sensitive adhesive preferably contains the crosslinking agent (B) together with the acrylic copolymer (A), and contains the above-mentioned pressure-sensitive adhesive additive as long as the effects of the present invention are not impaired. May be.

  Hereinafter, the acrylic copolymer (A) and the crosslinking agent (B) contained in an acrylic pressure-sensitive adhesive suitable as a pressure-sensitive adhesive that is a material for forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer will be described. .

(Acrylic copolymer (A))
The acrylic copolymer (A) contains 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 functional group. It has a structural unit (a2) derived from a monomer (hereinafter also referred to as “monomer (a2 ′)”).
The acrylic copolymer (A) includes the structural units (a3) derived from the monomer (a3 ′) other than the monomers (a1 ′) and (a1 ′) together with the structural units (a1) and (a2). You may have.
The form of 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.
An acrylic copolymer (A) may be used independently and may use 2 or more types together.
However, the acrylic copolymer (A1) is preferably an ultraviolet non-curable acrylic copolymer having no polymerizable functional group.

As carbon number of the alkyl group which a monomer (a1 ') has, Preferably it is 1-16, More preferably, it is 1-12, More preferably, it is 4-8, More preferably, it is 4-6.
Examples of the monomer (a1 ′) 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, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) Examples include acrylate and stearyl (meth) acrylate.
These monomers (a1 ′) may be used alone or in combination of two or more.

  In one embodiment of the present invention, the monomer (a1 ′) is preferably n-butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate, and more preferably n-butyl (meth) acrylate.

  The content of the structural unit (a1) is preferably 50 to 98 mol%, more preferably 60 to 97 mol%, still more preferably based on all structural units (100 mol%) of the acrylic copolymer (A). Is 70 to 96 mol%, more preferably 80 to 93 mol%.

Examples of the monomer (a2 ′) include a hydroxy group-containing monomer, a carboxy group-containing monomer, an epoxy group-containing monomer, an amino group-containing monomer, a cyano group-containing monomer, a keto group-containing monomer, and an alkoxysilyl group-containing monomer. .
These monomers (a2 ′) may be used alone or in combination of two or more.

In one embodiment of the present invention, the monomer (a2 ′) is preferably a carboxy group-containing monomer.
Examples of the carboxy group-containing monomer include (meth) acrylic acid, succinic acid, maleic acid, fumaric acid, itaconic acid, and derivatives thereof, but (meth) acrylic acid, succinic acid, and derivatives thereof are preferable. More preferred are mono (2-acryloyloxyethyl) succinate and 2-carboxyethyl acrylate.

  The content of the structural unit (a2) is preferably 2 to 50 mol%, more preferably 3 to 40 mol%, still more preferably based on all structural units (100 mol%) of the acrylic copolymer (A). Is 4 to 30 mol%, more preferably 7 to 20 mol%.

In one embodiment of the present invention, the acrylic copolymer (A) includes, as the structural unit (a2), a structural unit derived from any of mono (2-acryloyloxyethyl) succinate and 2-carboxyethyl acrylate ( It is preferable to have a2-1).
The content ratio of the structural unit (a2-1) in the structural unit (a2) is preferably 60 to 100 mol%, more preferably 70 to 100 mol, based on the total amount (100 mol%) of the structural unit (a2). %, More preferably 80 to 100 mol%, still more preferably 90 to 100 mol%, particularly preferably 100 mol%.
The content of the structural unit (a2-1) is preferably 2 to 45 mol%, more preferably 3 to 35 mol, based on all structural units (100 mol%) of the acrylic copolymer (A). %, More preferably 4 to 25 mol%, still more preferably 7 to 20 mol%.

Examples of the monomer (a3 ′) include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl. Examples include (meth) acrylates having a cyclic structure such as (meth) acrylates and imide (meth) acrylates, vinyl acetate, acrylonitrile, and styrene.
These monomers (a3 ′) may be used alone or in combination of two or more.

  The content of the structural unit (a3) is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, still more preferably based on the total structural units (100 mass%) of the acrylic copolymer (A). Is 0 to 5 mol%, more preferably 0 to 1 mol%.

  The mass average molecular weight (Mw) of the acrylic copolymer (A) is preferably 50,000 to 1,500,000, more preferably 150,000 to 1,300,000, still more preferably 250,000 to 1,100,000, still more preferably 350,000. ~ 900,000.

  The content of the acrylic copolymer (A) in the acrylic pressure-sensitive adhesive used in one embodiment of the present invention is preferably 50 to the total amount (100% by mass) of the active ingredients of the acrylic pressure-sensitive adhesive. 100 mass%, More preferably, it is 60-99.99 mass%, More preferably, it is 70-99.90 mass%, More preferably, it is 80-99.00 mass%, Most preferably, it is 90-98 mass%.

The acrylic pressure-sensitive adhesive used in one embodiment of the present invention may contain a pressure-sensitive adhesive resin other than the acrylic copolymer (A).
However, the content of the adhesive resin other than the acrylic copolymer (A) is preferably 0 to 100 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A) contained in the acrylic adhesive. More preferably, it is 0-60 mass parts, More preferably, it is 0-30 mass parts, More preferably, it is 0-15 mass parts, Most preferably, it is 0-10 mass parts.

(Crosslinking agent (B))
The acrylic pressure-sensitive adhesive used in one embodiment of the present invention preferably contains a crosslinking agent (B) together with the acrylic copolymer (A).
Examples of the crosslinking agent (B) include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a metal chelate crosslinking agent, an amine crosslinking agent, and an amino resin crosslinking agent.
These crosslinking agents (B) may be used independently and may use 2 or more types together.
In one embodiment of the present invention, the crosslinking agent (B) preferably contains an isocyanate-based crosslinking agent from the viewpoint of exhibiting sufficiently high adhesive force even in the thinned adhesive layer.

  The content of the crosslinking agent (B) in the acrylic pressure-sensitive adhesive used in one embodiment of the present invention is preferably 0.01 to 8 parts by mass, more preferably 100 parts by mass with respect to the acrylic copolymer (A). Is 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass.

<Release material>
The double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention preferably has a configuration in which a release material is further laminated on at least one surface of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.
In addition, since the double-sided pressure-sensitive adhesive sheet of the present invention has a support containing polylactic acid, when the double-sided pressure-sensitive adhesive sheet 2 shown in FIG. The acquired crying phenomenon can be effectively suppressed.

  Although there is no restriction | limiting in particular as a peeling material to be used, From the viewpoint of the ease of handling, the peeling sheet which apply | coated the release agent on the base material is preferable. The release sheet may be one in which a release agent is applied to both surfaces of the substrate and subjected to a release treatment, or may be one in which the release agent is applied to only one surface of the substrate and subjected to the release treatment.

Examples of the base material for the release material include paper base materials such as glassine paper, coated paper and cast coated paper; laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials; and polyethylene terephthalate and polybutylene terephthalate. And polyester films such as polyethylene naphthalate, and plastic films such as polyolefin films such as polypropylene and polyethylene.
Examples of the release agent include release agents containing a resin such as an olefin resin, an isoprene resin, a rubber elastomer such as a butadiene resin, a long-chain alkyl resin, an alkyd resin, a fluorine resin, or a silicone resin. It is done.

In addition, like the double-sided adhesive sheet 2 shown in FIG.1 (b), when using two peeling material 13a, 13b, the mutually same peeling material 13a, 13b may be used, and different things are used. Also good. However, the release material 13a and the release material 13b are adjusted so that the difference in the release force is different, and the release material (heavy release material) having a higher release force and the release material (lighter release force) than the heavy release material. It is preferable to use two types of release materials.
Moreover, when using the peeling material by which the peeling agent was apply | coated to both surfaces and the peeling process was used, it is preferable that it was adjusted so that the difference of the peeling force of each surface of the said peeling material may differ.

  Although there is no restriction | limiting in particular as thickness of a peeling sheet, Although it selects suitably, it is 10-200 micrometers normally, Preferably it is 25-150 micrometers, More preferably, it is 35-80 micrometers.

[Method for producing double-sided PSA sheet]
The manufacturing method of the double-sided adhesive sheet of this invention is not specifically limited.
For example, in the case of the double-sided pressure-sensitive adhesive sheet 1 of FIG. 1A, a pressure-sensitive adhesive is applied on one surface of the support 11 and dried to form the first pressure-sensitive adhesive layer 12a. Similarly, an adhesive can be applied on the other surface of the substrate and dried to form the second adhesive layer 12b.

Moreover, if it is the double-sided adhesive sheet 2 of FIG.1 (b), it can produce in the procedure of the following (ia)-(iiia).
(Ia) A pressure-sensitive adhesive is applied to the surface on which the release material 13a has been subjected to the peeling treatment, dried to form a first pressure-sensitive adhesive layer 12a, and the support 11 is bonded to produce a single-sided pressure-sensitive adhesive sheet. .
(Iia) An adhesive is applied in the same manner on the surface of the release material 13b prepared separately, and the second adhesive layer 12b is formed by drying.
(Iiia) Double-sided adhesive by bonding the surface of the support 11 of the single-sided pressure-sensitive adhesive sheet prepared in (ia) above to the surface of the second pressure-sensitive adhesive layer 12b formed in (iia) above. Sheet 2 is obtained.

In addition, as a manufacturing method of the double-sided adhesive sheet 2 of FIG.1 (b), it can also produce in the procedure of the following (ib)-(iiib).
(Ib) A pressure-sensitive adhesive is applied to the surface of the release material 13a on which the release treatment has been performed, and dried to form the first pressure-sensitive adhesive layer 12a.
(Iib) An adhesive is applied in the same manner on the surface of the release material 13b prepared separately, and the second adhesive layer 12b is formed by drying.
(Iiib) The double-sided pressure-sensitive adhesive sheet 2 is bonded to both surfaces of the support 11 by bonding the surface of the first pressure-sensitive adhesive layer 12a and the surface of the second pressure-sensitive adhesive layer 12b, respectively. obtain.

In the above method for producing a double-sided pressure-sensitive adhesive sheet, since the support 11 to be used is very thin, an application sheet may be used in order to improve the handleability of the support 11.
In this specification, the “application sheet” is affixed to support the core material or the pressure-sensitive adhesive sheet in order to improve the handling of the core material or pressure-sensitive adhesive sheet that is so thin that it is difficult to convey or affix. This means the sheet.
In the manufacturing process of the double-sided pressure-sensitive adhesive sheet, the application sheet is bonded to the support 11 while being laminated, and then the application sheet is peeled off. A double-sided PSA sheet may be produced by laminating one PSA layer.

  When applying the adhesive to the support or release material, in order to facilitate the formation of a thin adhesive layer, as described above, the adhesive is diluted with an organic solvent to form a solution of the adhesive. It is preferable that

Examples of the method for applying the pressure-sensitive adhesive on the support or the release material include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. There are known methods.
In order to prevent residual solvents and low-boiling components, and when a cross-linking agent is blended, apply a pressure-sensitive adhesive on the support or release material in order to develop cross-linking (reaction) and develop tackiness. It is preferable to heat-treat after forming the coating film.
As temperature conditions of heat processing, Preferably it is 70-150 degreeC, More preferably, it is 80-120 degreeC. The treatment time for the heat treatment is preferably 30 seconds to 5 minutes, more preferably 40 to 180 seconds.

[Physical properties of double-sided PSA sheet]
Even if the double-sided pressure-sensitive adhesive sheet of the present invention is thinned, the double-sided pressure-sensitive adhesive sheet can exhibit a sufficiently high adhesive force and is excellent in the effect of suppressing the tearing phenomenon.
About the double-sided pressure-sensitive adhesive sheet according to one aspect of the present invention, in an environment of 23 ° C. and 50% RH (relative humidity), after being attached to a stainless steel plate (SUS304 steel plate, No. 120 polishing), JIS Z0237: 2000 The adhesive strength measured according to the above is preferably 1.5 N / 25 mm or more, more preferably 2.0 N / 25 mm or more, still more preferably 2.5 N / 25 mm or more, still more preferably 3.0 N / 25 mm or more, Particularly preferably, it is 4.5 N / 25 mm or more.
In addition, in this specification, the said adhesive force points out the value measured based on JISZ0237: 2000, and specifically means the value measured by the method and conditions as described in the below-mentioned Example. To do.

The various physical property values shown in the description of the following examples are values measured as follows.
(1) Mass average molecular weight (Mw)
It is a value determined by standard polystyrene conversion, measured with the following equipment and conditions.
Device name: “HLC-8220GPC” (manufactured by Tosoh Corporation)
Column: “TSKgelGMHXL”, “TSKgelGMMHXL”, and “TSKgel2000HXL” (all manufactured by Tosoh Corporation) connected in sequence Developing solvent: Tetrahydrofuran Injection volume: 80 μl
Measurement temperature: 40 ° C
Flow rate: 1.0 mL / min
Detector: Differential refractometer

(2) Thickness measurement The thickness and total thickness of each layer of the double-sided PSA sheet were measured with a reflective film thickness meter (manufactured by Filmetrics, product name “F20”).
Specifically, using the reflective film thickness meter, the film thickness at any seven locations of the double-sided PSA sheet cut to 10 mm × 100 mm was measured, and the maximum value among the measured film thickness values at the seven locations and The average value of the film thickness values at five locations excluding the minimum value was calculated, and the average value was defined as the thickness or total thickness of each layer of the double-sided pressure-sensitive adhesive sheet to be measured.

(3) Film strength of support The measurement was performed according to JIS Z 1707 (1997).
Specifically, by using a creep meter (manufactured by Yamaden Co., Ltd., RE2-30005B), a semicircular needle having a diameter of 1.0 mm and a tip shape radius of 0.5 mm at a speed of 30 mm / min. The maximum stress shown until the needle pierced perpendicularly to the surface and penetrated was taken as the film strength (mN). In addition, measurement conditions other than these conformed to JIS Z1707 (1997).
The above measurement was performed three times on the target support to calculate the film strength, and the average value of the three times was taken as the film strength of the support.

Production Example 1
(Preparation of PLA film)
Polylactic acid resin (manufactured by PURAC, product name “PURASORB® PDL20”, copolymer of L-lactic acid and D-lactic acid, [L-lactic acid] / [D-lactic acid] = 50/50 (molar ratio) ) Was dissolved in ethanol to prepare a polylactic acid ethanol solution having a resin concentration of 5% by mass.
Then, as an application sheet, a polyolefin film (product name: “ZEONOR”, thickness 50 μm, manufactured by ZEON Co., Ltd.) is prepared, and the polylactic acid ethanol described above is formed on the application sheet so as to have a predetermined thickness after drying. The solution was applied and dried at 100 ° C. for 2 minutes to produce a polylactic acid film laminated on the application sheet.
Polylactic acid films having thicknesses of 0.2 μm, 0.5 μm, 0.7 μm, 1.0 μm, and 2.0 μm were prepared, respectively.

The details of the support and the pressure-sensitive adhesive used in Examples and Comparative Examples are shown below.
<Support>
PLA film (0.2):
A polylactic acid film having a thickness of 0.2 μm produced in Production Example 1 (membrane strength = 40 mN).
-PLA film (0.5):
A polylactic acid film having a thickness of 0.5 μm produced in Production Example 1 (membrane strength = 45 mN).
PLA film (0.7):
Polylactic acid film having a thickness of 0.7 μm (membrane strength = 97 mN) produced in Production Example 1.
PLA film (1.0):
A polylactic acid film having a thickness of 1.0 μm produced in Production Example 1 (membrane strength = 230 mN).
-PLA film (2.0):
A polylactic acid film having a thickness of 2.0 μm produced in Production Example 1 (membrane strength = 480 mN).
PET film (0.5):
Polyethylene terephthalate (PET) film having a thickness of 0.5 μm (membrane strength = 180 mN).
PET film (6.0):
PET film having a thickness of 6.0 μm (membrane strength = 2040 mN).
-Polyurethane film (6.0):
A polyurethane film having a thickness of 6.0 μm (film strength = 1540 mN) produced based on the description of Production Example 4 in paragraph [0073] of Patent Document 2 except that the thickness was changed from 2 μm to 6.0 μm.

<Adhesive>
-Adhesive (1):
An acrylic copolymer obtained by polymerizing n-butyl acrylate (BA) and succinic acid mono (2-acryloyloxyethyl) (2AOE) (BA / 2AOE = 90/10 (molar ratio), Mw = 280,000) 100 The solid content which mixed 0.45 mass part (solid content mass part) of the mass part (solid content mass part) and isocyanate type crosslinking agent (the Tosoh Corporation make, product name "Coronate L"), and diluted with ethyl acetate. A solution of acrylic adhesive having a concentration of 13% by mass.
-Adhesive (2):
Acrylic copolymer obtained by polymerizing n-butyl acrylate (BA) and acrylic acid (AAc) (BA / AAc = 96/4 (molar ratio), Mw = 1 million) 100 parts by mass (solid content part by mass) , 50 parts by mass (made by Harima Chemicals Co., Ltd., product name “Harristar TF”) (solid content part by mass), and isocyanate-based crosslinking agent (product name “Coronate L” by Tosoh Corporation) 0.1 A solution of an acrylic pressure-sensitive adhesive having a solid content concentration of 13% by mass, mixed with mass parts (mass parts of solid content) and diluted with ethyl acetate.
-Adhesive (3):
An acrylic copolymer obtained by polymerizing n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), acrylic acid (AAc), and 4-hydroxybutyl acrylate (4HBA) (BA / 2EHA / AAc / 4HBA = 70/30/3 / 0.05 (mass ratio), Mw = 440,000) 100 parts by mass (solid mass part), tackifier (product name “Pencel D125” manufactured by Arakawa Chemical Industries, Ltd.) 30 parts by mass (Solid content part by mass) and 2 parts by mass (solid content part) of an isocyanate-based cross-linking agent (product name “Coronate L” manufactured by Tosoh Corporation) were mixed and diluted with ethyl acetate. Acrylic adhesive solution.

Examples 1-6, Comparative Examples 2-5
On the release surface of the heavy release sheet (product name “SP-PET 381031”, manufactured by Lintec Corporation, 38 μm thick PET film released by silicone release agent), the types of adhesive shown in Table 1 were applied. And dried at 100 ° C. for 1 minute to form a first pressure-sensitive adhesive layer having a thickness shown in Table 1.
And the support body of the kind shown in Table 1 was bonded together on the surface of the exposed 1st adhesive layer, and the single-sided adhesive sheet was obtained.
In addition, when various PLA films are used as the support, the surface of the PLA film on which the application sheet is not laminated is left in a state in which the application sheet laminated on the PLA film is left in order to maintain handling properties. And the first pressure-sensitive adhesive layer were bonded together, and then the application sheet was removed to obtain a single-sided pressure-sensitive adhesive sheet.
In addition, the first pressure-sensitive adhesive is provided on the release-treated surface of a separately prepared light release sheet (product name “SP-PET381130” manufactured by Lintec Corporation, 38 μm thick PET film peel-treated with a silicone-based release agent). A pressure-sensitive adhesive of the type shown in Table 1, which is the same type of pressure-sensitive adhesive as used for forming the layer, was applied and dried at 100 ° C. for 1 minute to form a second pressure-sensitive adhesive layer having the thickness shown in Table 1.
And the surface on the support side of the above-mentioned single-sided pressure-sensitive adhesive sheet and the surface of the second pressure-sensitive adhesive layer are bonded, respectively, a heavy release sheet, a first pressure-sensitive adhesive layer, a support, a second pressure-sensitive adhesive layer, A double-sided PSA sheet (P) having a structure in which light release sheets were laminated in this order was produced.
Further, in the production process of the double-sided pressure-sensitive adhesive sheet (P), except that the “heavy release sheet” was replaced with “light release sheet (product name“ SP-PET381130 ”manufactured by Lintec Corporation)”, A double-sided pressure-sensitive adhesive sheet (Q) having a structure in which a light release sheet, a first pressure-sensitive adhesive layer, a support, a second pressure-sensitive adhesive layer, and a light release sheet were laminated in this order was also produced.

Comparative Example 1
On the release surface of the heavy release sheet (product name “SP-PET381031” manufactured by Lintec Corporation), the adhesive (1) is applied and dried at 100 ° C. for 1 minute to form an adhesive layer having a thickness of 2 μm. did.
Then, a light release sheet (product name “SP-PET381130” manufactured by Lintec Corporation) is laminated on the surface of the formed pressure-sensitive adhesive layer, and the heavy release sheet, the pressure-sensitive adhesive layer, and the light release sheet are attached to this surface. A double-sided PSA sheet (P ′) having a configuration laminated in order was prepared.
Further, in the production process of the double-sided pressure-sensitive adhesive sheet (P ′), except that the “heavy release sheet” was replaced with “light release sheet (manufactured by Lintec Corporation, product name“ SP-PET381130 ”), A double-sided pressure-sensitive adhesive sheet (Q) having a structure in which a light release sheet, a first pressure-sensitive adhesive layer, a support, a second pressure-sensitive adhesive layer, and a light release sheet were laminated in this order was also produced.

  The following evaluation was performed using the double-sided PSA sheet (P) or (P ′) and the double-sided PSA sheet (Q) prepared in Examples and Comparative Examples. These results are shown in Table 1.

(Evaluation 1) Adhesive strength measurement About "double-sided pressure-sensitive adhesive sheet (P) or (P ')" produced in Examples and Comparative Examples, the light release sheet was peeled off, and the surface of the pressure-sensitive adhesive layer was exposed to a thickness of 25 μm. After pasting the polyester film, it was cut into 25 mm × 300 mm to prepare a test piece.
Next, in a 23 ° C., 50% RH (relative humidity) environment, the heavy release sheet of the test piece was peeled off, and the surface of the pressure-sensitive adhesive layer exposed was coated with a stainless steel plate (SUS304 steel plate, 120 No. polishing) and allowed to stand for 24 hours in the same environment.
And the adhesive force 24 hours after pasting in the same environment was measured at a pulling speed of 300 mm / min by 180 ° peeling method in accordance with JIS Z0237: 2000.

(Evaluation 2) Crying separation test About "Double-sided PSA sheet (Q)" produced in Examples and Comparative Examples, when one of the light release sheets was peeled off, occurrence of tearing at the interface between the light release sheet and the adhesive layer The presence or absence was confirmed 20 times and evaluated according to the following criteria.
A: Crying did not occur in all of the 20 confirmed times.
B: Crying occurred once in 20 confirmed times.
C: Among the 20 times confirmed, weeped more than once.

According to Table 1, it can be seen that the double-sided PSA sheets prepared in Examples 1 to 6 are less likely to cause crying and have excellent adhesive strength even though the PSA layer is made thin.
On the other hand, the double-sided pressure-sensitive adhesive sheet produced in Comparative Example 1 resulted in a high frequency of occurrence of the tearing phenomenon. Moreover, although the double-sided adhesive sheet produced in Comparative Examples 2-5 was able to suppress generation | occurrence | production of a crying separation phenomenon, it was enough compared with the double-sided adhesive sheet produced in the Example with the thinning of the adhesive layer. Adhesive strength was not obtained.

Even if the double-sided pressure-sensitive adhesive sheet of the present invention is thinned, the double-sided pressure-sensitive adhesive sheet can exhibit a sufficiently high adhesive force and is excellent in the effect of suppressing the tearing phenomenon.
Therefore, the double-sided pressure-sensitive adhesive sheet of the present invention is used for, for example, bonding of two members at a location where the clearance is narrow, or temporary bonding at the time of processing, in portable electronic devices and optical devices that are required to be thinned. It is suitable for.

1, 2 Double-sided pressure-sensitive adhesive sheet 11 Support 12a First pressure-sensitive adhesive layer 12b Second pressure-sensitive adhesive layer 13a, 13b Release material

Claims (8)

A double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of the support,
The support comprises polylactic acid, and the support has a thickness of 1.5 μm or less;
Double-sided adhesive sheet.   The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the support has a film strength of 1 to 300 mN.   The double-sided pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the content of the polylactic acid is 70 to 100% by mass with respect to the total mass of the support.   The double-sided pressure-sensitive adhesive according to any one of claims 1 to 3, wherein at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is a layer formed from an acrylic pressure-sensitive adhesive containing an acrylic resin. Sheet.   The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are each independently 0.5 to 3.0 µm. .   The ratio of the thickness of the said support body with respect to the total thickness 100 of a 1st adhesive layer and a 2nd adhesive layer is 5.0-70.0, It is any one of Claims 1-5. Double-sided pressure-sensitive adhesive sheet as described in 1.   The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein a total thickness of the double-sided pressure-sensitive adhesive sheet when pasted on two adherends via the double-sided pressure-sensitive adhesive sheet is 6.0 µm or less. In an environment of 23 ° C. and 50% RH (relative humidity), the adhesive strength measured in accordance with JIS Z0237: 2000 after 24 hours from pasting on a stainless steel plate (SUS304 steel plate, No. 120 polishing) is 1. The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 7, which is 5 N / 25 mm or more.

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