JP2013018944A5 - - Google Patents

Description

Flame retardant adhesive composition and flame retardant adhesive sheet using the same

  The present invention relates to a flame retardant pressure-sensitive adhesive composition and a flame retardant pressure-sensitive adhesive sheet using the same. Specifically, the present invention relates to a flame retardant pressure-sensitive adhesive composition that can achieve both excellent flame retardancy and pressure-sensitive adhesive properties, and a flame retardant pressure-sensitive adhesive sheet using the same.

  With the high integration and high performance of electronic devices, flame resistance is also required for adhesive tapes used in electronic devices. In recent years, the use of halogenated flame retardants has been increasingly regulated by the RoHS directive and the WEEE directive. For this reason, the use of non-halogen flame retardants is strongly demanded. On the other hand, there is a demand for the development of a pressure-sensitive adhesive sheet that conforms to the UL94 standard, which is a flame retardance standard that exceeds the standard UL510 standard as a flame-retardant standard for electrical insulating pressure-sensitive adhesive sheets.

  For example, as a non-halogen flame retardant, a technique using a phosphate ester flame retardant, addition of a specific nitrogen-containing phosphate compound, and a phosphazene flame retardant is disclosed (for example, Patent Documents 1 to 3). In addition, a technique of using a phosphate ester flame retardant in combination with a tackifying resin has been studied (for example, Patent Document 4).

  However, when these non-halogen flame retardants are used, it is necessary to blend them in a larger amount than conventional halogen flame retardants. For this reason, when a flame retardant is blended in a large amount, the flame retardant precipitates on the surface of the adhesive layer, and the adhesiveness and mechanical properties are impaired. Moreover, although the pressure-sensitive adhesive sheet using these materials meets the UL510 standard, it is difficult to meet the UL94 standard.

Japanese Patent Laid-Open No. 2001-271044 JP 2006-219564 A JP 2002-338906 A JP 2006-219565 A

  Therefore, the present invention provides a flame retardant pressure-sensitive adhesive composition that can achieve both flame retardancy and adhesive properties without causing the flame retardant to precipitate on the surface of the adhesive layer even when a large amount of the flame retardant is blended. An object of the present invention is to provide a flame retardant adhesive sheet.

  As a result of intensive studies in view of the above problems, the inventors have added a specific amount and a specific blending ratio of a phosphoric ester and a phosphazene flame retardant and a tackifying resin to a specific acrylic pressure-sensitive adhesive. Thus, it has been found that both flame retardancy and adhesiveness can be achieved. The present invention has been completed based on this finding.

That is, the present invention provides the following flame-retardant pressure-sensitive adhesive composition and a flame-retardant pressure-sensitive adhesive sheet using the same.
(1) (A) a (meth) acrylic polymer comprising a copolymer of butyl acrylate and a monomer having a reactive functional group ;
(B) a phosphazene flame retardant,
(C) a phosphate ester flame retardant;
(D) a crosslinking agent;
(E) It contains an aromatic tackifying resin, and the total blending amount of the component (B) and the component (C) is 60 to 350 parts by mass with respect to 100 parts by mass of the component (A). A flame retardant pressure-sensitive adhesive composition comprising: (B) component and (C) component in a mass ratio of 25:75 to 75:25.
(2) The flame-retardant pressure-sensitive adhesive composition according to (1), wherein the amount of the component (E) is 60 to 250 parts by mass with respect to 100 parts by mass of the component (A).
(3) The flame-retardant pressure-sensitive adhesive composition according to (1) or (2), wherein the component (B) is a cyclic phenoxyphosphazene compound.
(4) The flame retardant pressure-sensitive adhesive composition according to any one of (1) to (3), wherein the component (C) is an aromatic condensed phosphate ester.
(5) A flame-retardant pressure-sensitive adhesive sheet obtained by shaping the flame-retardant pressure-sensitive adhesive composition according to any one of (1) to (4) into a film or a tape.

The flame-retardant pressure-sensitive adhesive composition of the present invention and the flame-retardant pressure-sensitive adhesive sheet using the same are excellent in flame retardancy while satisfying the pressure-sensitive adhesive properties.

  Hereinafter, the present invention will be specifically described. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

  The flame-retardant pressure-sensitive adhesive composition of the present invention contains components (A) to (E). Hereinafter, each component will be described.

[(A) component]
As the component (A) of the present invention, a (meth) acrylic polymer comprising a copolymer of butyl acrylate and a monomer having a reactive functional group is used. In the present invention, butyl acrylate is an essential monomer component from the viewpoint of compatibility with the later-described component (B) and component (C). In the present invention, (meth) acryl means acryl or methacryl.

In the present invention, examples of the monomer that can be copolymerized with butyl acrylate include monomers having a reactive functional group. Here, the reactive functional group refers to a functional group capable of reacting with the crosslinking agent to be discussed later. Examples of the reactive functional group include a carboxyl group, a hydroxyl group, and an amide group.

  Monomers containing carboxyl groups include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid or functional monomers derived from these monomers. Examples include a polymer. In addition, these may be used independently and may be used in combination of 2 or more type.

  Examples of the monomer containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxy (meth) acrylate. Butyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylactyl (meth) acrylate, 4- (meth) acrylate 4- Hydroxymethyl cyclohexyl, (meth) acrylic acid 3-chloro-2-hydroxypropyl, (meth) acrylic acid ethoxydiethylene glycol, (meth) acrylic acid caprolactone, (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, etc. Can be mentioned. In addition, these may be used independently and may be used in combination of 2 or more type.

  As monomers containing amide groups, (meth) acrylamide, α-ethyl (meth) acrylamide, N-methyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, N, N -Dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethyl-p-styrenesulfonamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) Examples include acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, and N, N-diethylaminopropyl (meth) acrylamide. In addition, these may be used independently and may be used in combination of 2 or more type.

In the present invention, the monomer having a reactive functional group is preferably a monomer containing a carboxyl group or a hydroxyl group from the viewpoint of improving cohesion.

  In the present invention, (meth) acrylic acid alkyl ester is exemplified as a component that can be copolymerized with the butyl acrylate and the monomer having a reactive functional group. The (meth) acrylic acid alkyl ester in the present invention is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms (excluding butyl acrylate). Specifically, for example, it has a linear or branched alkyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate (meta ) Acrylic acid alkyl ester. In addition, these may be used independently and may be used in combination of 2 or more type.

  As the component (A) of the present invention, an arbitrary monomer may be further added and copolymerized in addition to the above components within a range not impairing the object of the present invention. Optional monomers include acrylonitrile, polyethylene glycol acrylate, styrene, vinyl acetate, N-vinyl pyrrolidone and the like.

  (A) As a ratio of the component butyl acrylate, it is preferable that it is 50 mass% or more in all the monomer components, It is more preferable that it is 55 mass% or more, It is especially preferable that it is 70 mass% or more.

As a method for obtaining a copolymer of the component (A), the constituent monomers can be obtained by radical polymerization. As the radical polymerization method in the present invention, a conventionally known method can be used. Examples of the polymerization method include an emulsion polymerization method, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method.

  In the present invention, the glass transition temperature of the component (A) is preferably −60 to 20 ° C., more preferably −55 to 10 ° C. from the viewpoints of adhesiveness and heat resistance. When the glass transition temperature of (A) component is too high, the adhesive force of a to-be-adhered body and an adhesion layer will fall. When the glass transition temperature of the component (A) is too low, the heat resistance is lowered because the cohesive force is insufficient.

[Component (B)]
The component (B) in the present invention is specifically a phosphazene compound having a cyclic structure represented by the following general formula (1) or a linear structure represented by the following general formula (3). preferable.

  In the formula, n represents an integer of 1 or more, and X represents an alkoxy group having 1 to 4 carbon atoms or a phenoxy group represented by the following general formula (2).

In the formula, R ₁ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms.

  In the formula, m represents 0 or an integer of 1 or more, and Y represents an alkoxy group having 1 to 4 carbon atoms or a phenoxy group represented by the following general formula (4).

Wherein, _{R 2} represents a hydrogen atom, an alkyl group or an alkoxy group having 1 to 3 carbon atoms of 1 to 4 carbon atoms.

  In the present invention, it is preferable to use a cyclic phosphazene compound from the viewpoint of improving flame retardancy.

  Specific examples of the phosphazene compound having a cyclic structure in the present invention include SPB-100, SPS-100, SP-100, SPR-100, SA-100 (all manufactured by Otsuka Chemical Co., Ltd.), Ravitor FP-100, Ravitor. FP-110 (both manufactured by Fushimi Pharmaceutical Co., Ltd.) and the like can be mentioned. These may be used alone or in combination of two or more.

[Component (C)]
The component (C) in the present invention may be a conventionally known phosphate ester flame retardant. Specifically, for example, aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, trixylenyl phosphate, cresyl 2,6 xylenyl Aromatic phosphate esters such as phosphate, tris (tert-butylated phenyl) phosphate, tris (isopropylated phenyl) phosphate, triaryl isopropylate phosphate, and aromatic condensed phosphate esters such as resorcinol bisdixylenyl phosphate Is mentioned. These may be used alone or in combination of two or more.

  In the present invention, it is preferable to use an aromatic condensed phosphate ester from the viewpoint of cohesive strength, and it is more preferable to use an aromatic condensed phosphate ester that is solid at room temperature.

In the present invention, the component (B) and (C) the amount of the sum of components, within the 60 to 350 parts by weight with respect to the point from the component (A) 100 parts by weight of a cohesion and flame retardant It is necessary that it is 80 to 250 parts by mass. If the amount is too small, the desired flame retardancy cannot be obtained. On the other hand, if the amount is too large, the cohesive force cannot be maintained.

Moreover, in this invention, the compounding ratio of the said (B) component and (C) component needs to be 25: 75-75: 25 by mass ratio. When the above mass ratio is deviated, either the component (B) or the component (C) is precipitated, and the adhesive property is deteriorated.

[(D) component]
In the present invention, the flame retardant pressure-sensitive adhesive composition needs to contain a crosslinking agent. By using the crosslinking agent, the crosslinking reaction with the component (A) proceeds. As a result, the cohesive force of the pressure-sensitive adhesive composition is improved.

  The component (D) in the present invention is not particularly limited as long as it can be crosslinked with the component (A), and examples thereof include an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent.

  As an isocyanate type crosslinking agent, what is necessary is just a conventionally well-known isocyanate type crosslinking agent, For example, a polyvalent isocyanate compound, its oligomer, a prepolymer, etc. are mentioned. Examples of the polyvalent isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4′-diisocyanate, Examples include diphenylmethane-2,4′-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, dicyclohexylmethane-2,4′-diisocyanate, and lysine isocyanate. In addition, you may use these isocyanate type crosslinking agents individually by 1 type or in combination of 2 or more types.

  The epoxy crosslinking agent may be a conventionally known epoxy crosslinking agent, for example, a compound having two or more epoxy groups in the molecule. Specifically, for example, sorbitol tetraglycidyl ether, trimethylolpropane triglycidyl ether, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyl-m-xylenediamine, triglycidyl-p-aminophenol, hydroquinone diglycidyl Examples include ether, polypropylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycidyl terephthalate, and triglycidyl isocyanurate. These epoxy crosslinking agents may be used alone or in combination of two or more.

  As a compounding quantity of (D) component in this invention, it is preferable that it is 0.1-3.0 mass parts with respect to 100 mass parts of said (A) component. When there are too many compounding quantities of (D) component, the softness | flexibility of a flame-retardant adhesive composition will fall. When there are too few compounding quantities of (D) component, the cohesion force of a flame-retardant adhesive composition cannot be ensured.

(E) Aromatic tackifying resin As the component (E) in the present invention, it is necessary to use an aromatic tackifying resin from the viewpoint of flame retardancy. Examples of aromatic tackifying resins include styrene resins, xylene resins, terpene-phenol resins, aromatic petroleum resins, phenol resins, and the like. These aromatic tackifying resins may be used singly or in combination of two or more.

  In this invention, it is preferable that the compounding quantity of (E) component is 60-250 mass parts with respect to 100 mass parts of (A) component from the point of adhesive force and holding power. When there are too few compounding quantities, desired adhesive force cannot be maintained. If the amount is too large, the desired holding power cannot be maintained.

  In the present invention, the (B) component and the (C) component are set to the above-mentioned specific blending amount and specific blending ratio, and the (E) component is added. For this reason, even if it mix | blends a large amount of (B) component and (C) component, adhesion characteristics can be satisfied, preventing precipitation of the adhesion layer surface. Moreover, it can conform to UL94 standard which is a strict flame retardance standard. Therefore, the flame-retardant pressure-sensitive adhesive composition of the present invention and the flame-retardant pressure-sensitive adhesive sheet using the same have excellent flame resistance and pressure-sensitive adhesive properties.

  In this invention, you may contain various additives, such as a viscosity modifier, a plasticizer, a crosslinking (auxiliary) agent, a filler, antioxidant, and a dispersing agent, to such an extent that the objective of this invention is not impaired.

  The flame-retardant pressure-sensitive adhesive composition of the present invention can be prepared by mixing each of the above components and, if necessary, various additives.

Next, the flame-retardant pressure-sensitive adhesive sheet of the present invention will be described.
The flame-retardant pressure-sensitive adhesive sheet of the present invention includes a base material and a pressure-sensitive adhesive layer formed on at least one side of the base material.

  As the substrate, a film-like or tape-like member having a thickness of 4 to 250 μm is preferable.

  Specific examples of the base material include polyester, polycarbonate, triacetyl cellulose, polyimide, polyamide, polyamideimide, polyphenylene sulfide, polyetherimide, polyethersulfone, and other synthetic resins, nonwoven fabrics, woven fabrics, metals, and the like. . The substrate may be transparent or colored. Further, the surface of the substrate is not limited to a smooth surface, and the surface may be processed into a mat shape, primer-treated, or flame-retardant treated.

  As a manufacturing method of the flame-retardant pressure-sensitive adhesive sheet of the present invention, first, the above-mentioned flame-retardant pressure-sensitive adhesive composition is dissolved or dispersed in an organic solvent or the like with respect to the base material, and the solid content concentration is 20 to 50% by mass. An adhesive layer forming coating solution is prepared as described above. An adhesive layer is formed by applying the adhesive layer-forming coating solution to at least one surface of the substrate and then drying. Thus, the flame-retardant pressure-sensitive adhesive sheet of the present invention can be obtained.

  The organic solvent used for the adhesive layer-forming coating solution is not particularly limited as long as it dissolves the flame-retardant adhesive composition of the present invention. Examples of the organic solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl isobutyl ketone and the like.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 2 to 100 μm, more preferably 5 to 60 μm, and particularly preferably 10 to 50 μm. If the thickness of the pressure-sensitive adhesive layer cannot be ensured, sufficient adhesion to the adherend cannot be obtained. If the pressure-sensitive adhesive layer is too thick, there is a risk of poor drying.

  There are no particular restrictions on the method of applying the flame retardant adhesive composition, for example, wire bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin. A conventionally known coating method using a coater or the like may be used. In addition, you may transfer to a base material, after apply | coating a coating liquid directly to a base material, or apply | coating to the film which has mold release property for formation of an adhesion layer.

  There is no restriction | limiting in particular also about a drying method, Conventionally well-known drying methods, such as hot air drying and reduced pressure drying, can be used. About drying conditions, what is necessary is just to set suitably by the kind of solvent used for each material and coating liquid, the film thickness of an adhesion layer, etc., and 60-180 degreeC is common.

  The flame-retardant pressure-sensitive adhesive composition of the present invention or the pressure-sensitive adhesive sheet using the same can be used for products that require flame retardancy.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited at all by these Examples.

Example 1
After adding methyl ethyl ketone as a solvent to the mixture of each component shown in Table 1 so that a solid content might be 40%, it stirred and mixed and the adhesion layer formation coating liquid was prepared.
The prepared adhesive layer-forming coating solution was applied to the surface of a 25 μm-thick polyimide film (trade name: Kapton 100V, manufacturer: Toray DuPont) as a base material using a baker type applicator, and then 2 at 130 ° C. A pressure-sensitive adhesive layer having a thickness of 25 μm was obtained by heating and drying for a minute.
Next, the 50 μm thick single-sided silicone-treated PET film (trade name: MRF, manufacturer: Mitsubishi Chemical Polyester Film Co., Ltd.) was adhered to the surface of this adhesive layer as a release liner, and the temperature was 40 ° C. By curing for 1 month, a flame-retardant adhesive sheet was obtained.

(Examples 2-6 and Comparative Example 1-8)
A flame-retardant pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 using each component described in Tables 1 and 2.

  Each component of Table 1 and Table 2 is as follows.

(A) Component (A-1)
Constituent monomer: butyl acrylate, acrylate glass transition temperature: -31 ° C, mass average molecular weight: 270,000 (A-2)
Constituent monomer: butyl acrylate, acrylate glass transition temperature: −40 ° C., mass average molecular weight: 1.3 million (A-3)
Constituent monomer: 2-ethylhexyl acrylate, glass transition temperature of acrylate: -64 ° C, mass average molecular weight: 800,000 (A-4)
Constituent monomer: butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate glass transition temperature: -34 ° C, mass average molecular weight: 640,000

(B) Component cyclic phosphazene compound (trade name: SPB-100, manufacturer: Otsuka Chemical)
(C) Component aromatic condensed phosphate ester (trade name: PX-200, manufacturer: Daihachi Chemical)
(D) Component (D-1)
Epoxy crosslinking agent (trade name: TETRAD-C, manufacturer: Mitsubishi Gas Chemical)
(D-2)
Isocyanate-based crosslinking agent (trade name: Coronate L, manufacturer: Nippon Polyurethane Industry)
(E) Component xylene phenol novolak resin (softening point 80 ° C)

  Evaluation items were evaluated by the following methods. Note that the notation “−” indicates that evaluation is impossible.

(1) Compatibility The obtained flame-retardant pressure-sensitive adhesive sheet was visually confirmed, and precipitation of the flame retardant was evaluated according to the following criteria.
○: No precipitation occurs at the time of preparing the flame-retardant pressure-sensitive adhesive sheet and after curing for 1 month.
(Triangle | delta): It does not precipitate at the time of flame-retardant adhesive sheet preparation, but deposits only at an edge part after 1-month curing.
X: It does not precipitate at the time of preparation of a flame-retardant pressure-sensitive adhesive sheet, but deposits on the entire surface after curing for 1 month.
(2) Flame retardancy In accordance with UL94 vertical combustion test method, flame retardancy was evaluated according to the following criteria.
○: Conforming to UL94VTM-0 standard.
X: Not conforming to UL94VTM-0 standard.
(3) Holding power Based on JISZ0237, the produced adhesive sheet was cut | judged to 25 mm width, and the test piece was produced. The test piece was affixed to a SUS plate so that an area of 25 mm × 25 mm was in contact, and the size (mm) of the deviation was measured when left for 60 minutes under the conditions of a temperature of 80 ° C. and a load of 1000 g. The measurement was performed 3 times, and the average value is shown in the table. The holding force is preferably 0.5 or less. In addition, about the sample which fell, it showed as fall.
(4) Probe tack value Based on ASTM D 2979, the adhesion force when a 5 mm diameter cylindrical probe was pulled away from the flame-retardant adhesive sheet was measured. The measurement conditions were a temperature of 23 ° C., a contact load of 2 N / cm 2, a contact time of 10 seconds, and a separation speed of 10 mm / second. The measurement was performed 5 times, and the average value is shown in the table. It is preferable that it is 3N or more.

  The results are shown in Tables 1 and 2.

From the results of Table 1, it was found that all the examples had high flame retardancy. Further, since the holding force and the probe tack value are also good, it can be said that it has sufficient adhesive properties.
On the other hand, for Comparative Examples 1 and 2 and Comparative Example 8 in Table 2, since any of the comparative examples does not contain any of the component (B), the component (C), and the component (E), compatibility and holding power Both the probe tack value and the probe tack value were inferior. About the comparative example 3 whose monomer of (A) component is 2-ethylhexyl acrylate, the desired characteristic was not able to be acquired. In Comparative Example 4 in which the blending amount of the component (B) is small and Comparative Example 5 in which the blending amount of the component (C) is small, the compatibility, holding power, and probe tack value were all poor. About Comparative Example 6 with many compounding quantities of (B) component and (C) component, the desired retention strength was not acquired. About the comparative example 7 with few compounding quantities of (B) component and (C) component, it was inferior to the flame retardance .

Claims (5)

(A) a (meth) acrylic polymer comprising a copolymer of butyl acrylate and a monomer having a reactive functional group ;
(B) a phosphazene flame retardant,
(C) a phosphate ester flame retardant;
(D) a crosslinking agent;
(E) It contains an aromatic tackifying resin, and the total blending amount of the component (B) and the component (C) is 60 to 350 parts by mass with respect to 100 parts by mass of the component (A). A flame retardant pressure-sensitive adhesive composition comprising: (B) component and (C) component in a mass ratio of 25:75 to 75:25.   The flame-retardant pressure-sensitive adhesive composition according to claim 1, wherein the blending amount of the component (E) is 60 to 250 parts by mass with respect to 100 parts by mass of the component (A).   The flame retardant pressure-sensitive adhesive composition according to claim 1 or 2, wherein the component (B) is a cyclic phenoxyphosphazene compound.   The flame retardant pressure-sensitive adhesive composition according to claim 1, wherein the component (C) is an aromatic condensed phosphate ester. The flame-retardant adhesive sheet which shape | molded the flame-retardant adhesive composition of any one of Claims 1-4 in the shape of a film or a tape.