JP6025858B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to an adhesive sheet. More specifically, excellent flame retardancy and adhesion without using halogen-based flame retardants that generate toxic gases during incineration or aromatic phosphate-containing flame retardants that may cause endocrine disrupting chemicals. The present invention relates to a flame-retardant pressure-sensitive adhesive sheet having characteristics and high-temperature pressure-sensitive adhesive characteristics.

  Flame resistance is required in various fields such as electronic parts, electronic equipment, aircraft, and nuclear power plants. In order to cope with this, flame retardancy is imparted to members used in these fields, and at the same time, the adhesive tape or sheet that fixes these members is required to have high flame retardancy of the VTM-0 level in the UL94 standard. ing.

In order to improve the flame retardance of an adhesive tape or a sheet, generally, a method of incorporating various flame retardants into an adhesive composition is employed. As such flame retardants, halogen compounds such as bromine and chlorine, and those in which antimony oxide is used in combination with halogen compounds are common.
However, the halogen compound flame retardant has a problem that it is harmful to the human body and the environment because a halogen gas is generated during combustion.
Therefore, in order to solve these problems, PTL 1 discloses a pressure-sensitive adhesive composition comprising a phosphate ester flame retardant and a nitrogen-containing phosphate compound flame retardant as flame retardants other than halogen compounds. Flame retardant adhesive tapes using sapphire have been proposed.

JP 2006-219564 A

However, since the flame retardant pressure-sensitive adhesive tape of Patent Document 1 contains an aromatic-containing phosphate ester flame retardant as an essential component, there is a concern that bisphenol A, which is known as an endocrine disrupting chemical substance, is generated during combustion. Further, the flame retardant pressure-sensitive adhesive tape has a problem that the pressure-sensitive adhesive property at a high temperature is low.
The present invention has been made under such circumstances, and is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a flame retardant on at least one side of a substrate, and the pressure-sensitive adhesive layer serves as a flame retardant, and a halogen-based flame retardant And flame retardant (UL94 VTM-0), adhesive properties (8N / 25mm or more), and high temperature (80 ° C) adhesive properties (8N / 25mm or more) without aromatic phosphorus-containing flame retardant An object is to provide a pressure-sensitive adhesive sheet.

As a result of intensive studies to achieve the above object, the present inventors have obtained the following knowledge.
The pressure-sensitive adhesive layer provided on at least one side of the substrate is composed of an acrylic copolymer (A), a specific phosphate ester flame retardant (B1) having no aromatic ring, and a nitrogen-containing phosphate compound-based flame retardant. And an acrylic copolymer (A) containing a carboxyl group-containing monomer unit (such as an acrylic acid unit) at a specific ratio, and further comprising the pressure-sensitive adhesive composition. It has been found that when the total amount of the flame retardants (B1) and (B2) is within a specific range with respect to the acrylic copolymer (A), a pressure-sensitive adhesive sheet suitable for the above purpose can be obtained. .
The present invention has been completed based on such findings.

That is, the present invention provides the following [1] to [7].
[1] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on at least one side of a substrate, wherein the pressure-sensitive adhesive layer has an acrylic copolymer (A) and an aromatic ring represented by the following general formula (1). A phosphoric acid ester-based flame retardant (B1) and a nitrogen-containing phosphate compound-based flame retardant (B2), and an acrylic copolymer (A) as a monomer unit. Phosphoric acid ester flame retardant (B1) containing a carboxyl group-containing monomer unit at a ratio of 15 to 35% by mass and having no aromatic ring, and nitrogen-containing phosphate compound-based flame retardant The pressure-sensitive adhesive sheet, wherein the total amount of the flame retardant (B2) is 40 to 90 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A).

(Wherein R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen, an alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms, and D represents a substituent. 1 represents an optionally substituted alkylene group having 1 to 5 carbon atoms or an optionally substituted oxyalkylene group having 1 to 5 carbon atoms, n is a number of 0 to 3, and n is 2 or more. In this case, a plurality of OR ⁴ may be the same or different, and R ¹ and R ² , R ² and R ³ , or R ¹ and R ³ may be bonded to each other to form a ring, When n is 1 or more, R ¹ , R ² , or R ³ and one R ⁴ may be bonded to each other to form a ring, wherein the ring may have a substituent. Good.)

[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the pressure-sensitive adhesive composition does not contain any of a halogen compound, an antimony compound, and an aromatic-containing phosphate ester compound.
[3] Phosphate ester flame retardant having no aromatic ring (B1) is tributyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, tris (2-ethylhexyl) phosphate, trioctyl phosphate, tridecyl phosphate, and condensed phosphorus The pressure-sensitive adhesive sheet according to the above [1] or [2], which is at least one selected from acid esters.
[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the phosphoric acid ester flame retardant (B1) having no aromatic ring has a phosphorus content of 8 to 20% by mass.
[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the acrylic monomer unit constituting the acrylic polymer (A) has 7 or less side chain carbon atoms.
[6] The pressure-sensitive adhesive composition comprises phosphate ester flame retardant (B1) having no aromatic ring and nitrogen-containing phosphate compound flame retardant (B2) in a mass ratio of 1: 0.2 to The pressure-sensitive adhesive sheet according to any one of the above [1] to [5], which is contained at a ratio of 1: 5.
[7] The pressure-sensitive adhesive sheet according to any one of the above [1] to [6], wherein the base material has flame retardancy conforming to VTM-0 in a test according to UL94 standard.

  According to the present invention, there is provided a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a flame retardant on at least one surface of a base material, wherein the pressure-sensitive adhesive layer serves as a flame retardant, a halogen flame retardant, an aromatic-containing phosphorus flame retardant. To provide an adhesive sheet that can satisfy flame retardancy (UL94 VTM-0), adhesive properties (8 N / 25 mm or more), and high temperature (80 ° C.) adhesive properties (8 N / 25 mm or more) without containing. it can.

It is a cross-sectional schematic diagram which shows the one aspect | mode of the structure of the adhesive sheet of this invention.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on at least one side of a substrate, and the pressure-sensitive adhesive layer is an aromatic polymer (A) and a fragrance represented by the general formula (1). It consists of an adhesive composition containing a phosphate ester flame retardant (B1) having no ring and a nitrogen-containing phosphate compound flame retardant (B2).
The structure of the adhesive sheet of this invention will not be specifically limited if it has an adhesive layer on the single side | surface or both surfaces of a base material.
FIG. 1 is a diagram showing an embodiment of the configuration of the pressure-sensitive adhesive sheet of the present invention. The configuration of the pressure-sensitive adhesive sheet of the present invention is not limited to the pressure-sensitive adhesive sheet 1a having the pressure-sensitive adhesive layer 12a on one side of the substrate 11 as shown in FIG. 1A, but as shown in FIG. The pressure-sensitive adhesive sheet 1b in which a release sheet 13a is further laminated on the pressure-sensitive adhesive layer 12a formed on one side may be used.
Moreover, the adhesive sheet of this invention may be the adhesive sheet 1c which has the adhesive layers 12a and 12b on both surfaces of the base material 11 like FIG.1 (c), and each of this adhesive layer 12a and 12b. An adhesive sheet in which release sheets 13a and 13b are further laminated may be used. In addition, in FIG.1 (c), the display of peeling sheet 13a, 13b is abbreviate | omitted.

[Base material]
As the base material used for the pressure-sensitive adhesive sheet of the present invention, it is preferable to use a material having flame retardancy conforming to VTM-0 in a test according to the UL94 standard. In the present invention, “conforms to VTM-0 in a test conforming to UL94 standard” means that in a test conforming to the thin material vertical combustion test method of the flame retardant test standard UL94 published by Underwriters Laboratories, VTM rank Is determined to be VTM-0.

As such a base material, a base material made of a resin having flame retardancy as a single resin, a base material made of a resin containing a flame retardant, a base material in which the above resin is coated or laminated on a sheet, and a metal A foil or the like can be used. In the present invention, it is preferable to use a resin base material.
Examples of the resin having flame retardancy as a single resin include polyimide resins such as polyetherimide resins and polyphenylene etherimide resins, polyaramid resins, polyphenylene sulfide resins, and polyether ether ketone resins.

As a resin used for a base material composed of a resin containing a flame retardant, in addition to the above resin having flame retardancy alone, polycarbonate resin, polystyrene resin, polyethylene resin, polyester resin, polyolefin resin, polyurethane resin, phenol Examples include resins, urea resins, EVA resins, acrylic resins, acrylonitrile butadiene styrene resins (ABS resins), epoxy resins, polystyrene-polycarbonate alloy resins, polystyrene-ABS alloy resins, polyamide resins, and the like.
Examples of the flame retardant include organic flame retardants such as phosphorus flame retardants, silicone compounds, melamine compounds, hindered amine compounds, and guanidine compounds, and inorganic flame retardants such as antimony compounds and metal hydroxides. . You may use the said flame retardant individually or in combination of 2 or more types.

  Moreover, you may use the base material by which the resin which has a flame retardance with the above-mentioned resin simple substance, or the resin containing the flame retardant is coated or laminated on the sheet. Examples of the sheet include sheet-like plastic, paper such as impregnated paper, woven fabric, and non-woven fabric.

Among the above-mentioned base materials, from the viewpoint of flame retardancy, it is a base material made of polyimide resin, polyaramid resin, polyphenylene sulfide resin, polyether ether ketone resin, or a base material in which these resins are coated on the sheet. Is preferred.
From the viewpoint of environmental friendliness, a base material that does not substantially contain a halogen-based flame retardant is preferable, and a base material that does not substantially contain any flame retardant is more preferably used.

Specific examples of the base material used in the pressure-sensitive adhesive sheet of the present invention include Lumirror ZV10 (trade name, a film obtained by coating a polyethylene terephthalate film with a polyimide resin, manufactured by Toray Industries, Inc.), Torelina (trade name, polyphenylene sulfide resin). Film, manufactured by Toray Industries, Inc., Mikutron (trade name, polyaramid resin film, manufactured by Toray Industries, Inc.), Kapton (trade name, polyimide resin film, manufactured by Toray DuPont Co., Ltd.), Superior UT (trade name, polyetherimide) Resin film, manufactured by Mitsubishi Resin Co., Ltd., dialy (trade name, flame retardant-containing polyethylene terephthalate resin film, manufactured by Mitsubishi Resin Co., Ltd.) and the like.
Also, LAXRON Polycarbonate SDB-3 (trade name, flame retardant-containing polycarbonate resin film, manufactured by Tokiwa Electric Co., Ltd.), Sun Lloyd Barrier (trade name, polyphenylene ether resin film, manufactured by Sumitomo Bakelite Co., Ltd.), Sun Lloyd Eco Sheet Polyca (Trade name, non-halogen flame retardant-containing polycarbonate resin film, manufactured by Sumitomo Bakelite Co., Ltd.), Ultem (trade name, polyetherimide resin film, manufactured by Asahi Glass Co., Ltd.), Lexan (trade name, polycarbonate resin sheet, manufactured by Asahi Glass Co., Ltd.) ), Baroques (trade name, polybutylene terephthalate resin film, manufactured by Asahi Glass Co., Ltd.), safety film (trade name, polyethylene resin film, manufactured by Oida Kogyo Co., Ltd.), and the like. Note that the present invention is not limited to these product examples.

  Although the thickness of a base material is suitably determined according to the use of an adhesive sheet, it is 1-100 micrometers normally, Preferably it is 5-100 micrometers, More preferably, it is 10-80 micrometers.

[Adhesive layer]
The pressure-sensitive adhesive sheet of the present invention comprises an acrylic polymer (A) and a phosphate ester flame retardant (B1) having no aromatic ring represented by the general formula (1) on at least one surface of the substrate. And a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing a nitrogen-containing phosphate compound-based flame retardant (B2).
In the pressure-sensitive adhesive sheet of the present invention, the thickness per side of the pressure-sensitive adhesive layer is preferably 5 to 50 μm, and more preferably 10 to 40 μm, from the viewpoint of achieving both flame retardancy and adhesive strength.
In addition, in this invention, "the thickness per one side of an adhesive layer" means each thickness of the adhesive layer provided in the single side | surface or both surfaces of a base material (each of Z1, Z2 of Fig.1 (a)-(c)) ).

<Adhesive composition>
The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer used in the present invention comprises an acrylic copolymer (A) and a phosphate ester flame retardant (B1) having no aromatic ring represented by the general formula (1). ) And a nitrogen-containing phosphate compound-based flame retardant (B2), and may contain a crosslinking agent, other additives, an organic solvent, and the like as necessary. Hereinafter, each component contained in the pressure-sensitive adhesive composition will be described.

(Acrylic copolymer (A))
The acrylic copolymer (A) used in the present invention comprises a structural unit (a1) derived from a (meth) acrylic acid alkyl ester (a1) (hereinafter also referred to as “monomer (a1)”), and a carboxyl group-containing monomer ( A copolymer containing the structural unit (a2) derived from a2) (hereinafter also referred to as “monomer (a2)”) is preferred. In addition, from the viewpoint of flame retardancy of the obtained pressure-sensitive adhesive sheet, the number of side chain carbon atoms of the acrylic monomer unit such as the monomer (a1) constituting the acrylic copolymer (A) is preferably 7 or less. More preferably, it is 5 or less.
Moreover, there is no restriction | limiting in particular about the copolymerization form of an acryl-type copolymer (A), Any of a random copolymer, a block copolymer, and a graft copolymer may be sufficient.

(Monomer (a1))
The (meth) acrylic acid alkyl ester (a1) is a main component monomer of the acrylic copolymer (A). The side chain carbon number of the monomer (a1) is preferably 7 or less, and more preferably 5 or less. If this carbon number is 7 or less, the flame retardance of the adhesive sheet obtained is favorable.
Examples of the monomer (a1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth) acrylate. And (meth) acrylic acid alkyl esters having an alkyl group having 1 to 10 carbon atoms such as cyclohexyl (meth) acrylate. These monomers (a1) may be used alone or in combination of two or more.
Among these, from the viewpoint of adhesive performance, butyl (meth) acrylate is preferable, and butyl acrylate is more preferable.
In addition, when using 2 or more types of monomers (a1) together, it is preferable that a butyl (meth) acrylate is included at least. The proportion of butyl (meth) acrylate in the monomer (a1) is preferably 60 to 100% by mass, more preferably 75 to 100% by mass, still more preferably 90 to 100% by mass, and still more preferably substantially. 100% by mass.

(Monomer (a2))
The monomer (a2) is a carboxyl group-containing monomer, preferably carboxylic acid.
Preferable examples of the carboxylic acid include (meth) acrylic acid, crotonic acid, fumaric acid, maleic acid and the like. Among these, (meth) acrylic acid is preferable, and acrylic acid is more preferable.

(Monomer (a3))
The acrylic copolymer (A) used in the present invention has a structural unit (a3) derived from the monomer (a3) other than the monomers (a1) and (a2) within a range not impairing the effects of the present invention. You may do it.
Examples of the monomer (a3) include (meth) acrylate monomers having a crosslinkable functional group such as a hydroxyl group and an amino group; vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; Aromatic vinyl monomers such as methylstyrene and vinyltoluene; diene monomers such as butadiene and isoprene; and nitrile monomers such as (meth) acrylonitrile.
These monomers (a3) may be used alone or in combination of two or more.

The acrylic copolymer (A) used in the present invention contains a carboxyl group-containing monomer unit (a2) as a monomer unit in a proportion of 15 to 35% by mass, preferably 18 to 32% by mass. If the content is less than 15% by mass, the pressure-sensitive adhesive sheet obtained has insufficient adhesive properties at high temperatures, whereas if it exceeds 35% by mass, the adhesive properties are insufficient.
The mass ratio of the structural unit (a1) and the structural unit (a2) contained in the acrylic copolymer (A) [structural unit (a1) / structural unit (a2)] is from the viewpoint of improving adhesive strength. Preferably it is 85 / 15-65 / 35, More preferably, it is 82 / 18-68 / 32.
In addition, the acrylic copolymer (A) may have a structural unit (a3) derived from another monomer (a3) other than the structural units (a1) and (a2). Content of a structural unit (a3) is 10 mass% or less with respect to 100 mass% of all the structural units of an acrylic copolymer (A) from a viewpoint of a flame retardance and adhesive performance, More preferably, it is 5 mass% or less. More preferably, it is 1% by mass or less, and still more preferably substantially 0% by mass.

The weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 100,000 to 1,500,000, more preferably 120,000 to 1,000,000, and even more preferably 150,000 to 700,000 from the viewpoint of improving the adhesive strength. More preferably, it is 170,000 to 400,000. If Mw is 100,000 or more, the cohesive force of the pressure-sensitive adhesive layer to be formed can be improved, and sufficient adhesive force can be obtained. Moreover, if Mw is 1.5 million or less, the elasticity modulus of an adhesive layer will not become high too much and the fall of adhesive force can be suppressed.
In addition, in this invention, the value of a weight average molecular weight (Mw) is a value of standard polystyrene conversion measured by a gel permeation chromatography (GPC) method, and specifically based on the method as described in an Example. It is a measured value.

(Method for synthesizing acrylic copolymer (A))
The acrylic copolymer (A) can be synthesized by adding a solvent and a polymerization initiator to the monomer mixture composed of the above monomer components as necessary to advance the polymerization reaction.
Examples of the solvent to be used include ethyl acetate and toluene. The polymerization reaction can be allowed to proceed in the absence of a solvent.
Examples of the polymerization initiator to be added include azobisisobutyronitrile and benzoyl peroxide.
The addition amount of the polymerization initiator is preferably 0.01 to 1 part by mass, more preferably 0.1 to 0.5 part by mass with respect to 100 parts by mass of the monomer mixture.
Although it does not specifically limit about polymerization conditions, It is preferable to superpose | polymerize over 2 to 30 hours at the temperature of 50-90 degreeC after deaeration with nitrogen gas.

<Resin component other than component (A)>
The pressure-sensitive adhesive composition used in the present invention may contain a resin component other than the component (A) as long as the content of the component (A) satisfies the above range.
Examples of the resin component other than the component (A) include a urethane resin, an acrylic urethane resin, a urethane polyester resin, and butyl rubber.

(Crosslinking agent)
The pressure-sensitive adhesive composition used in the present invention may contain a crosslinking agent as necessary. Since the acrylic copolymer (A) contains a carboxyl group-containing monomer unit as a crosslinking point, it can be crosslinked with a crosslinking agent. Thereby, the adhesive characteristic of the obtained adhesive layer becomes a more favorable thing.
As a crosslinking agent, it is preferable to use an isocyanate type crosslinking agent from a reactive viewpoint.
Examples of isocyanate crosslinking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane. Polyisocyanate compounds such as triisocyanate and polymethylene polyphenyl isocyanate, adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane, burettes and isocyanurates of these polyisocyanate compounds, and further these polyisocyanate compounds And known polyether polyols and polyesters Ether polyols, acrylic polyols, polybutadiene polyols, adducts, etc. and polyisoprene polyol and the like.
Among these isocyanate-based crosslinking agents, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl from the viewpoint of physical properties as an adhesive. One or more selected from −3,5,5-trimethylcyclohexyl isocyanate and modified products thereof are preferred, and a modified product of 2,4-tolylene diisocyanate is particularly preferred.
This isocyanate-based crosslinking agent is preferably used at a ratio of 0.01 to 10 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A).

(Phosphate flame retardant having no aromatic ring (B1))
The pressure-sensitive adhesive composition used in the present invention includes the above-mentioned acrylic copolymer (A), a phosphate ester flame retardant having no aromatic ring (B1), and a nitrogen-containing phosphate compound flame retardant (B2). ).

  The phosphate ester flame retardant (B1) having no aromatic ring has a structure represented by the following general formula (1).

(Wherein R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen, an alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms, and D represents a substituent. 1 represents an optionally substituted alkylene group having 1 to 5 carbon atoms or an optionally substituted oxyalkylene group having 1 to 5 carbon atoms, n is a number of 0 to 3, and n is 2 or more. In this case, a plurality of OR ⁴ may be the same or different, and R ¹ and R ² , R ² and R ³ , or R ¹ and R ³ may be bonded to each other to form a ring, When n is 1 or more, R ¹ , R ² , or R ³ and one R ⁴ may be bonded to each other to form a ring, wherein the ring may have a substituent. Good.)

In the general formula (1), specific examples of the alkyl group having 1 to 12 carbon atoms represented by R ¹ , R ² , R ³ and R ⁴ include a methyl group, an ethyl group, a propyl group, an isopropyl group, and various types. Examples include butyl group, pentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group and the like. In these, a C2-C10 alkyl group is preferable and a C4-C8 alkyl group is more preferable.
Specific examples of R ^1, R ^2, R ³ and cycloalkyl group having 3 to 12 carbon atoms represented by R ⁴ include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, cyclononyl Group, cyclodecyl group, cyclododecyl group and the like. In these, a C5-C8 cycloalkyl group is preferable and a C5-C6 cycloalkyl group is more preferable.
In the general formula (1), R ¹ and R ² may be bonded to each other to form a ring, and the same applies to R ² and R ³ and R ¹ and R ³ . When n is 1 or more, R ¹ and one R ⁴ may be bonded to each other to form a ring, and the same applies to R ² and one R ⁴ , R ³ and one R ^4. .
The ring preferably has 3 to 6 ring member carbon atoms. In addition, the ring may have one or more substituents, and examples of the substituent include an alkyl group having 1 to 4 carbon atoms and an alkyloxy group.

Phosphate ester flame retardant (B1) having no aromatic ring includes tributyl phosphate (TBP), trihexyl phosphate, tricyclohexyl phosphate, tris (2-ethylhexyl) phosphate (TOP), trioctyl phosphate, tridecyl phosphate And at least one selected from condensed phosphates are preferably used. In addition, in this invention, condensed phosphate ester means the compound whose n is 1-3 in the said General formula (1), or its mixture.
Among these, those having a phosphorus content of 8 to 20% by mass are more preferable. If the phosphorus content is 8% by mass or more, the flame retardancy is good, while if it is 20% by mass or less, the tackiness is good.
Examples of commercially available phosphate ester flame retardants (B1) having no aromatic ring include tributyl phosphate (TBP), tris (2-ethylhexyl) phosphate (TOP) commercially available from Daihachi Chemical Industry Co., Ltd., And DAIGUARD880, which is a non-halogen condensed phosphate ester commercially available from Daihachi Chemical Industry Co., Ltd., and the like. These phosphate ester flame retardants (B1) having no aromatic ring may be used singly or in combination of two or more.

(Nitrogen-containing phosphate compound flame retardant (B2))
The nitrogen-containing phosphate compound-based flame retardant (B2) is used in combination with the above-described phosphate ester-based flame retardant (B1) having no aromatic ring.
The nitrogen-containing phosphate compound-based flame retardant (B2) is not particularly limited, and examples thereof include ammonium polyphosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate, phosphate ester amide, and guanidine phosphate. It is done. These nitrogen-containing phosphate compounds may be used alone or in combination of two or more.
As an example of a commercial item of a nitrogen content phosphate compound type flame retardant (B2), ADK STAB FP-2200 marketed from ADEKA Corporation is mentioned.

  In the pressure-sensitive adhesive sheet of the present invention, a phosphoric ester-based flame retardant having no aromatic ring (B1) and a nitrogen-containing phosphate compound-based flame retardant (B2) in the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer The total amount of is 40 to 90 parts by mass, preferably 50 to 85 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). If the total amount is less than 40 parts by mass, the flame retardancy is insufficient, and if it exceeds 90 parts by mass, the adhesive properties are deteriorated.

In the present invention, the pressure-sensitive adhesive composition comprises a phosphate ester flame retardant (B1) having no aromatic ring and a nitrogen-containing phosphate compound flame retardant (B2) in a mass ratio of 1: 0. From the viewpoint of flame retardancy and pressure-sensitive adhesive performance, it is preferable that the ratio is from 2 to 1: 5, more preferably from 1: 0.5 to 1: 2.
In addition, it is preferable that the said adhesive composition does not contain any of a halogen compound, an antimony compound, and an aromatic containing phosphate ester type compound.

(Other ingredients)
The pressure-sensitive adhesive composition can be blended with other components as long as the effects of the present invention are not impaired. Examples of other components include ultraviolet absorbers, antioxidants, antiseptics, antifungal agents, plasticizers, antifoaming agents, and wettability adjusting agents.

[Peeling sheet]
The pressure-sensitive adhesive sheet of the present invention may be one in which a release sheet is laminated on a pressure-sensitive adhesive layer, for example, as shown in FIG.
Although there is no restriction | limiting in particular as a peeling sheet used for the adhesive sheet of this invention, From the viewpoint of the ease of handling, the peeling sheet which apply | coated the release agent on the sheet base material is preferable. The release sheet may be one in which a release agent is applied to both surfaces of the sheet substrate and subjected to a release treatment, or may be one in which the release agent is applied to only one surface of the sheet substrate and subjected to the release treatment.
As the sheet substrate used for the release sheet, for example, a paper substrate such as glassine paper, coated paper, cast coated paper, laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper substrates, or polyethylene terephthalate, Examples thereof include polyester films such as polybutylene terephthalate and polyethylene naphthalate, and plastic films such as polyolefin films such as polypropylene and polyethylene.
Examples of the release agent include rubber elastomers such as olefin resins, isoprene resins, butadiene resins, long chain alkyl resins, alkyd resins, fluorine resins, silicone resins, and the like.

Although there is no restriction | limiting in particular in the thickness of a peeling sheet, Usually, 20-200 micrometers, Preferably it is 25-150 micrometers.
Although it does not specifically limit as thickness after drying of the layer which consists of a release agent in a release sheet, When applying a release agent in a solution state, Preferably it is 0.01-2.0 micrometers, More preferably, it is 0.03-. 1.0 μm. When a plastic film is used as the sheet base material of the release sheet, the thickness of the plastic film is preferably 3 to 50 μm, more preferably 5 to 40 μm.

[Method for producing adhesive sheet]
The manufacturing method of the adhesive sheet of this invention is not specifically limited.
As a method for producing the pressure-sensitive adhesive sheet 1a shown in FIG. 1 (a), a method for producing a pressure-sensitive adhesive layer 12a by applying and drying the above-mentioned pressure-sensitive adhesive composition on a substrate 11, or peeling. On the sheet, the above-mentioned pressure-sensitive adhesive composition is applied and dried to form a pressure-sensitive adhesive layer 12a. The pressure-sensitive adhesive layer 12a and the substrate 11 are bonded together to obtain the pressure-sensitive adhesive sheet 1b, and then the release sheet is removed. And the production method.
Moreover, as a manufacturing method of the adhesive sheet 1b shown by FIG.1 (b), after manufacturing the said adhesive sheet 1a, laminating | stacking the peeling sheet 13 on the adhesive layer 12a, or on a peeling sheet, In addition, a method in which the pressure-sensitive adhesive composition is applied and dried to form a pressure-sensitive adhesive layer 12a, and the pressure-sensitive adhesive layer 12a and the substrate 11 are bonded to each other can be used.
As a method for producing the pressure-sensitive adhesive sheet 1c shown in FIG. 1 (c), the pressure-sensitive adhesive composition 12 is applied and dried on one side of the base material 11 to form the pressure-sensitive adhesive layer 12a. In the same manner, a method for forming the pressure-sensitive adhesive layer 12b on the other surface of the sheet, and two sheets provided with the pressure-sensitive adhesive layer on the release sheet are prepared, and the pressure-sensitive adhesive layer and the substrate of the sheet are prepared. And a method for producing the pressure-sensitive adhesive sheet 1b by removing the release sheet.

When applying the pressure-sensitive adhesive composition, in order to facilitate the formation of a thin pressure-sensitive adhesive layer on the substrate, the pressure-sensitive adhesive composition is diluted with an organic solvent, and a coating solution having an appropriate solid content concentration is prepared. It is preferable to prepare and apply this.
Examples of the organic solvent to be used include toluene, ethyl acetate, methyl ethyl ketone, and the like.

There is no restriction | limiting in particular in the method of forming an adhesive layer on a base material or a peeling sheet, For example, the method of forming the coating liquid which mix | blended said organic solvent with a well-known coating method is mentioned.
Examples of the coating method include known methods such as spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, and gravure coating. .
In addition, in order to prevent residual solvents and low-boiling components, and when a cross-linking agent is blended, in order to promote cross-linking (reaction) and develop adhesiveness, it is heated after being applied to a substrate or a release sheet. It is preferable to process.

[Physical properties of adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention produced as described above has an adhesive strength of 8 N / 25 mm or higher at room temperature (23 ° C., 50% RH (relative humidity)) at a high temperature (measurement method described in the following examples). (80 ° C.) Adhesive strength is 8 N / 25 mm or more, and flame retardancy is VTM-0 according to UL94 standard, and can fully satisfy all of normal temperature adhesive strength, high temperature (80 ° C.) adhesive strength and flame retardancy. .

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The weight average molecular weight (Mw) indicated in the description of the following examples is a value obtained by measurement under the following conditions using “HLC-8020” manufactured by Tosoh Corporation and calculated in terms of standard polystyrene.
(Measurement condition)
Column: “TSK gel GMHXL (× 2)” “TSK gel G2000HXL” (both manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Developing solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Detector: Differential refractometer

Moreover, the normal temperature adhesive strength test, the high temperature (80 degreeC) adhesive strength test, and flame-retardant evaluation of the adhesive sheet obtained in the Example were performed by the method shown below.
(1) Room temperature adhesive strength test The release sheet was peeled off, and the test piece of the adhesive sheet cut to 25 mm x 300 mm was attached to an adherend (SUS304 steel plate) in an environment of 23 ° C and 50% RH. It was set as the sample for a test. Based on JIS Z0237, the adhesive force 24 hours after sticking was measured by a 180 ° peeling method at a pulling speed of 300 mm / min.

(2) Adhesive strength test at high temperature (80 ° C.) The release sheet was peeled off, and the test piece of the adhesive sheet cut to 25 mm × 300 mm was pasted on the adherend (SUS304 steel plate) in an environment of 23 ° C. and 50% RH. And it was set as the sample for adhesive force tests. The sample was conditioned for 1 day in a 23 ° C., 50% RH environment, and then placed in an 80 ° C. constant temperature bath for 1 hour. Thereafter, the adhesive strength was measured at a pulling speed of 300 mm / min by a 180 ° peeling method in an 80 ° C. environment.

(3) Flame Retardancy Evaluation The peel-off sheet of the prepared adhesive sheet is peeled off, and a test according to the flame retardant test standard UL94 thin material vertical combustion test method issued by Underwriters Laboratories is conducted. Judged. The sample size of the pressure-sensitive adhesive sheet used for the evaluation was 50 mm × 200 mm, and the test was performed with the pressure-sensitive adhesive layer outside.
The criteria for determining the VTM rank are as follows.
VTM-0; burning time of the sample is within 10 seconds, and the absorbent cotton is not ignited by the burned material or the falling object, and further, the burning up to the marked line (125 mm position from the lower end of the sample) is not recognized.
VTM-1: The burning time of the sample is within 30 seconds, and the absorbent cotton is not ignited by the burned material or the fallen material, and further, combustion up to the marked line is not recognized.
VTM-2: The burning time of the sample is within 30 seconds, and burning up to the marked line is not observed.
Those conforming to VTM-0 were accepted and others were rejected.
In this flame retardant evaluation, the test was performed four times, and the number of times of passing VTM-0 having the strictest conditions was counted. For example, in the flame retardancy evaluation of Table 1, the notation “3/4” indicates that the number of times of passing VTM-0 is 3 times out of 4 tests.

Production Example 1
(Preparation of acrylic copolymer solution 1)
As a monomer component, 80 parts by mass of butyl acrylate and 20 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate as a solvent, and 0.2 parts by mass of azobisisobutyronitrile as a polymerization initiator are placed in a reactor. Mixed. After deaeration with nitrogen gas for 4 hours, the temperature was gradually raised to 60 ° C., followed by polymerization reaction with stirring for 24 hours, and an ethyl acetate solution containing an acrylic copolymer 1 having a weight average molecular weight of 600,000 (solid A partial concentration of 33% by mass) was obtained.

Production Example 2
(Preparation of acrylic copolymer solution 2)
An acrylic copolymer 2 having a weight average molecular weight of 600,000 is obtained by carrying out a polymerization reaction in the same manner as in Production Example 1 except that 75 parts by mass of butyl acrylate and 25 parts by mass of acrylic acid are used as monomer components. An ethyl acetate solution (solid content concentration: 33% by mass) was obtained.

Production Example 3
(Preparation of acrylic copolymer solution 3)
Acrylic copolymer 3 having a weight average molecular weight of 600,000 is obtained by performing a polymerization reaction in the same manner as in Production Example 1 except that 70 parts by mass of butyl acrylate and 30 parts by mass of acrylic acid are used as monomer components. An ethyl acetate solution (solid content concentration: 33% by mass) was obtained.

Production Example 4
(Preparation of acrylic copolymer solution 4)
Acrylic copolymer 4 having a weight average molecular weight of 650,000 is obtained by performing a polymerization reaction in the same manner as in Production Example 1 except that 90 parts by mass of butyl acrylate and 10 parts by mass of acrylic acid are used as monomer components. An ethyl acetate solution (solid content concentration: 33% by mass) was obtained.

Example 1
(Preparation of adhesive sheet)
100 parts by mass (solid content) of an ethyl acetate solution containing the acrylic copolymer 1 obtained in Production Example 1 and an isocyanate-based crosslinking agent (trade name “Coronate L”, manufactured by Nippon Polyurethane Co., Ltd., trimethylolpropane as a crosslinking agent) 2.2 parts by mass (solid content) of ethyl acetate solution of modified tolylene diisocyanate (solid content 75% by mass) and tris (2-ethylhexyl) phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) as a phosphate ester flame retardant (Trade name “TOP”) 40 parts by mass and a nitrogen-containing phosphate flame retardant (manufactured by ADEKA, trade name “Adekastab FP-2200”) 30 parts by mass, solid content concentration is 10% by mass The solution was diluted with ethyl acetate to prepare an adhesive composition solution.
This solution was applied to a silicone-treated 38 μm polyester film (product name “SP-PET 381031” manufactured by Lintec Corporation) as a release sheet so that the thickness of the pressure-sensitive adhesive layer after drying was 20 μm. After drying at 100 ° C. for 1 minute, the base material is a polyethylene terephthalate (PET) film coated with polyimide resin on both sides (trade name “Lumirror ZV30 # 40”, manufactured by Toray Industries, Inc., thickness: 47 μm, UL94 standard (Adapted to VTM-0 in a similar test) and seasoned in an environment of 23 ° C. and 50% RH for 7 days to prepare an adhesive sheet.
In addition, the thickness and total thickness of each layer of the pressure-sensitive adhesive sheet were measured using a constant pressure thickness measuring machine PG-02J manufactured by Teclock Co., Ltd.

Examples 2-7 and Comparative Examples 1-10
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the pressure-sensitive adhesive composition was changed as shown in Table 1.

  Table 2 shows the room-temperature adhesive strength, the adhesive strength at high temperature (80 ° C.), and the flame retardancy evaluation results of the adhesive sheets obtained in Examples 1 to 7 and Comparative Examples 1 to 10.

The details of the main agent (acrylic copolymer), crosslinking agent, and flame retardant in Table 1 are as follows.
BA: Butyl acrylate AAc: Acrylic acid Crosslinking agent: Isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name “Coronate L”, ethyl acetate solution of trimethylolpropane-modified tolylene diisocyanate (solid content: 75 mass%))
Flame retardant (B1): Phosphate ester flame retardant having no aromatic ring TOP: Tris (2-ethylhexyl) phosphate (manufactured by Daihachi Chemical Industry Co., Ltd., TOP)
TBP: Tributyl phosphate (Daihachi Chemical Industry Co., Ltd., TBP)
・ DAIGUARD880 (Daihachi Chemical Industry Co., Ltd., aromatic ring-free condensed phosphate ester flame retardant)
Phosphate ester flame retardants other than (B1) BDP: Bisphenol A bis-diphenyl phosphate (Daihachi Chemical Industries, CR-741)
Flame retardant (B2): Nitrogen-containing phosphate compound flame retardant (manufactured by ADEKA Corporation, Adeka Stub FP-2200)

  According to the present invention, a halogen-based flame retardant that generates a toxic halogen-containing gas during incineration, antimony oxide that has been pointed out to have an adverse effect on the human body, bisphenol A that has been pointed out as an endocrine disrupting chemical, and the like It is possible to provide a flame-retardant pressure-sensitive adhesive sheet having excellent flame retardancy, pressure-sensitive adhesive properties and high-temperature pressure-sensitive adhesive properties without using an aromatic-containing phosphate ester-based flame retardant that has a risk of generating odors.

1a, 1b, 1c Adhesive sheet 11 Base material 12a, 12b Adhesive layer 13a Release sheet

Claims (7)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on at least one side of a base material, wherein the pressure-sensitive adhesive layer has an acrylic copolymer (A) and a phosphorus that does not have an aromatic ring represented by the following general formula (1) It consists of an adhesive composition containing an acid ester flame retardant (B1) and a nitrogen-containing phosphate compound flame retardant (B2), and the acrylic copolymer (A) contains a carboxyl group as a monomer unit. A monomer unit is contained in a proportion of 15 to 35% by mass, and the nitrogen-containing phosphate compound flame retardant (B2) is ammonium polyphosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate, and guanidine phosphate. A phosphoric ester-based flame retardant (B1) and a nitrogen-containing phosphate compound-based flame retardant (B2) which are at least one selected from the group consisting of: With Metering, pressure-sensitive adhesive sheet, which is a 40 to 90 parts by weight of the acrylic copolymer (A) 100 parts by mass of.

(Wherein R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen, an alkyl group having 4 to 12 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms, and D represents a substituent. 1 represents an optionally substituted alkylene group having 1 to 5 carbon atoms or an optionally substituted oxyalkylene group having 1 to 5 carbon atoms, n is a number of 0 to 3, and n is 2 or more. In this case, the plurality of OR ⁴ may be the same or different, and R ¹ and R ² , R ² and R ³ , or R ¹ and R ³ may be bonded to each other to form a ring, When n is 1 or more, R ¹ , R ² , or R ³ and one R ⁴ may be bonded to each other to form a ring, and the ring may have a substituent. However, R ¹ , R ² , R ³ and R ⁴ are not all hydrogen. )   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive composition does not contain any of a halogen compound, an antimony compound, and an aromatic-containing phosphate ester compound.   Phosphate ester flame retardant (B1) having no aromatic ring is composed of tributyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, tris (2-ethylhexyl) phosphate, trioctyl phosphate, tridecyl phosphate, and condensed phosphate ester. The pressure-sensitive adhesive sheet according to claim 1 or 2, which is at least one selected.   The adhesive sheet in any one of Claims 1-3 whose phosphorus content rate of the phosphate ester type flame retardant (B1) which does not have an aromatic ring is 8-20 mass%.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the acrylic monomer unit constituting the acrylic copolymer (A) has 7 or less side chain carbon atoms.   The pressure-sensitive adhesive composition comprises a phosphate ester-based flame retardant (B1) having no aromatic ring and a nitrogen-containing phosphate compound-based flame retardant (B2) in a mass ratio of 1: 0.2 to 1: 5. The pressure-sensitive adhesive sheet according to claim 1, which is contained at a ratio of   The adhesive sheet in any one of Claims 1-6 in which a base material has the flame retardance which adapts to VTM-0 in the test according to UL94 specification.