JPH11181380A - Flame-retardant adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant adhesive compsn. which is excellent in adhesiveness, resistances to soldering heat and heat aging, and flame retardance and is useful as an adhesive for flexible printed circuit substrates. SOLUTION: This compsn. contains (A) 1 pt. carboxylated nitrile-butadiene rubber, (B) 0.01-0.25 pt. poly-N-glycidyl epoxy resin, (C) 1.0-4.0 pts. at least difunctional epoxy resin having no N-glycidyl group, (D) 0.3-1.1 pts. resin-coated red phosphorus flame retardant having an average particle size of 5 μm or lower, and (E) 0.4-2.0 pts. auxiliary flame retardant comprising a silane-treated metal hydroxide of the group 2 or 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant adhesive composition, and more particularly to a flame-retardant adhesive excellent in adhesiveness, solder heat resistance, heat aging resistance and flame retardancy and useful as an adhesive for flexible printed circuit boards. The present invention relates to a water-soluble adhesive composition.

[0002]

2. Description of the Related Art A flexible printed circuit board made of a film such as a polyimide resin film or a polyester resin film and a metal foil such as a copper foil or an aluminum foil bonded to the flexible printed circuit board with an adhesive is a flexible printed wiring material. Cameras, calculators, telephones (for home use, PHS)
It is used in many fields such as printers, audio equipment such as DVDs (digital video discs), and the like. In recent years, as these electric and electronic devices have become increasingly lighter, thinner and smaller, and circuits have become more complex, flexible printed wiring materials used in these devices have become increasingly difficult to use between flexible printed circuit boards and metal foils. The adhesiveness of the base is
There is a demand for higher solder heat resistance and heat aging resistance. Further, with the establishment of the PL method, strict requirements have been placed on the flame retardancy of materials.

[0003]

However, various types of adhesives, such as fluororesins, epoxy-novolak resins, nitrile-phenol resins, polyester resins, acrylic resins, and urethane resins, conventionally used as adhesives for flexible printed circuit boards have been used. Adhesives based on resins have not been capable of sufficiently satisfying increasingly sophisticated requirements, especially in terms of solder heat resistance and heat aging resistance.

Accordingly, an object of the present invention is to provide a flame-retardant adhesive composition which is excellent in adhesiveness, solder heat resistance, heat aging resistance and flame retardancy and is useful as an adhesive for flexible printed circuit boards. is there.

[0005]

Means for Solving the Problems The present inventors have developed an adhesive property,
The challenge was to find an adhesive composition with excellent solder heat resistance, heat aging resistance, and flame retardancy. First, a carboxyl group-containing nitrile rubber and a composition containing an epoxy resin as the main component were converted to phosphorus-based flame retardants. The addition of the agent was studied. as a result,
It has been found that the resin-coated red phosphorus flame retardant is most effective for improving the adhesiveness, solder heat resistance and flame retardancy. However, a composition containing a red phosphorus-based flame retardant alone is markedly colored, and also generates an odor peculiar to red phosphorus and does not contain a thixotropic agent such as Aerosil. When the flexible printed circuit board and the metal foil are bonded to each other, there is a problem that the flow of the composition into the land becomes large, which causes a short circuit or the like in the flexible printed circuit board.

Therefore, as a result of further study, it was found that by adding a silane-treated hydroxide of a Group 2 or Group 3 metal, coloring could be performed without greatly reducing the flexibility of the adhesive. The present invention was found to be able to improve, and it was found that, by adding a poly-N-glycidyl-type epoxy resin, it was possible to improve the flow into the land portion, and thus reached the present invention.

That is, the present invention provides (A) a carboxyl group-containing nitrile butadiene rubber, (B) a poly N-glycidyl type epoxy resin, (C) a bifunctional or more epoxy resin having no N-glycidyl group, (D) A resin-coated red phosphorus-based flame retardant having an average particle size of 5 μm or less, and (E) a flame retardant auxiliary comprising a silane-treated hydroxide of a Group 2 or Group 3 metal, the following weight ratios: The present invention provides a flame-retardant adhesive composition containing (in terms of solid content). (B) / (A) = 0.01 to 0.25 (C) / (A) = 1.0 to 4.0 (D) / (A) = 0.3 to 1.1 (E) / ( A) = 0.4-2.0

Hereinafter, the flame-retardant adhesive composition of the present invention (hereinafter, referred to as “the composition of the present invention”) will be described in detail.

The composition of the present invention comprises (A) a carboxyl group-containing nitrile butadiene rubber, (B) a poly N-glycidyl type epoxy resin, (C) a difunctional or higher epoxy resin having no N-glycidyl group, (D) ) A resin-based red phosphorus flame retardant and (E) a flame retardant auxiliary comprising a metal hydroxide as main components.

The carboxyl group-containing nitrile butadiene rubber which is the component (A) of the composition of the present invention is obtained by carboxylating the terminal of an acrylonitrile-butadiene copolymer rubber (A-1), or acrylonitrile, butadiene and A copolymer rubber (A-2) or the like obtained by terpolymerizing a carboxyl group-containing monomer can be used.

In the acrylonitrile-butadiene copolymer rubber (A-1), the acrylonitrile and butadiene preferably have a molar ratio of 3/97 to 60/40 in molar ratio. The one having a molar ratio of 5/95 to 45/55 is particularly preferable in that a composition that forms a cured product having excellent flexibility can be obtained.

Also, a terpolymer rubber (A-A) comprising an acrylonitrile-butadiene-carboxyl group-containing monomer is used.
In 2), the content ratio of acrylonitrile / butadiene is 60/40 to 3/97, and preferably 5/95 to 45/45 in that a composition that forms a cured product having excellent adhesiveness and heat resistance is obtained. 55.

The carboxyl group-containing nitrile butadiene rubber has a carboxyl group content of 0.5 to 13 mol%.
And from 1 to 8 mol% is preferable in that a composition having excellent adhesiveness and heat resistance can be obtained.

Specific examples of the carboxyl group-containing nitrile-butadiene rubber include Hiker CTBN and Hiker C.
TBNX, Hiker 1072 (above, manufactured by Goodrich), Nipol 1072 (manufactured by Zeon Corporation), Chemigam 550 (manufactured by Goodyear), Tylac 221A (manufactured by Standard Plans), etc. Is mentioned.

In the present invention, the carboxyl group-containing nitrile-butadiene rubber can be used in a form dissolved or dispersed in an organic solvent when further thinning is required. As the solvent to be used, for example, methyl ethyl ketone, methyl isobutyl ketone, ethanol, isopropanol, methyl cellosolve and the like are preferable in terms of cost and ease of drying in B-stage.

The poly (N) component (B) of the composition of the present invention
The glycidyl type epoxy resin is a compound having a group represented by the following general formula (b) in the molecule.

[0017]

Embedded image (Where n is an integer of 1 to 6)

This poly N-glycidyl type epoxy resin is generally synthesized from the corresponding amine and epihalohydrin.

Specific examples of the poly N-glycidyl type epoxy resin include those represented by the following formulas (b-1) to (b-6).

[0020]

Embedded image(Where R¹And R^TwoMay be the same or different
A hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Of the compounds represented by these formulas (b-1) to (b-6)
Among them, in terms of cost, the formulas (b-5) and (b-6)
Is preferably represented by These formulas (b-1) to
As a specific example of the compound represented by (b-6), a compound represented by the formula (b-)
In 5), R ¹And R^TwoIs a hydrogen atom,
As a compound corresponding to the 4'-substituted compound, tetrad-X (tri
Which are marketed under the trade name of Ryoko Gas Chemical Co., Ltd.)
Further, in formula (b-6), a compound corresponding to a p-substituted product
As a compound, Epicoat YX4 (manufactured by Yuka Shell Co., Ltd.)
And the like marketed under the trade name.

The composition of the present invention contains, as the component (C), the epoxy resin having a bifunctional or higher functionality having no N-glycidyl group of the component (B). This epoxy resin (C) contains two or more epoxy groups in one molecule,
An epoxy resin having no N-glycidyl group represented by the formula (b). As the epoxy resin (C),
For example, 2,2-bis (4'-oxyphenyl) propane, 2,2-bis (4'-hydroxyphenyl) butane, 1,1-bis (4'-hydroxyphenyl) ethane, bis (4-hydroxyphenyl) ) Methane, 1,1,
A polyphenol-based epoxy resin comprising a glycidyl etherified product of a polyphenol such as 2,2-tetrakis (4'-hydroxyphenyl) ethane, 4-hydroxydiphenyl ether, or p- (4-hydroxyphenyl) phenol; Resin consisting of a glycidyl etherified product of a compound; epoxy resin consisting of a glycidyl etherified product of a polyhydric phenol such as catechol, resorcin, hydroquinone, and phloroglucin; Epoxy resin: alicyclic epoxy tree composed of glycidylated alicyclic polyhydric phenol such as vinylcyclohexene dioxide, limonene dioxide, dicyclopentadiene dioxide Fat; phthalic acid, cyclohexane-
An epoxy resin composed of a polyglycidyl esterified product of an ester condensate of a polycarboxylic acid such as 1,2-dicarboxylic acid is exemplified. Among these, polyphenol-based epoxy resins and novolak-type epoxy resins are preferred in terms of cost and in that a composition that forms a cured product having excellent adhesiveness, solder heat resistance and flexibility can be obtained.

The resin-coated red phosphorus flame retardant used as the component (D) in the composition of the present invention is obtained by coating the surface of particulate red phosphorus with a resin. The average particle size of the resin-coated red phosphorus-based flame retardant is 5 μm or less in that the applied surface when the composition of the present invention is made into the B-stage does not become uneven. It is preferably 2 μm or less from the viewpoint that a composition having excellent storage stability and excellent dispersibility during coating can be obtained. The resin that coats the surface of the red phosphorus-based flame retardant is not particularly limited as long as it has good compatibility with the matrix resin. For example, a phenol resin, an epoxy resin and the like can be mentioned. As a specific example of this resin-coated red phosphorus flame retardant,
Commercial products having trade names such as Novaled 280C and Novaled 580C (both manufactured by Rin Kagaku) can be mentioned. Red phosphorus with no resin coating on its surface is chemically unstable and may decompose by reacting with oxygen in the air or moisture in the solvent, forming phosphoric acid and causing circuit corrosion. .

In the composition of the present invention, the flame retardant aid used as the component (E) is a hydroxide of a Group 2 or Group 3 metal, the surface of which has been subjected to silane treatment. Examples of the hydroxide of a metal belonging to Group 2 or Group 3 include magnesium hydroxide, aluminum hydroxide, and calcium hydroxide. Among them, particularly, in that a composition excellent in adhesiveness and solder heat resistance is obtained,
Aluminum hydroxide is preferred. In addition, the silane treatment
This is a process of coating the surface of the metal hydroxide with a silane compound such as trimethylchlorosilane or dimethyldichlorosilane. B1403ST, B1403ST
Commercially available products having a trade name such as F013 (both manufactured by Nippon Light Metal Co., Ltd.). Addition of a small amount of a metal hydroxide that has not been subjected to a silane treatment increases the viscosity of the adhesive composition to a level outside of practical use, so that it is difficult to use the metal hydroxide in a large amount, and a sufficient flame-retardant effect may not be obtained.

The (E) flame retardant aid has an average particle diameter of 10 μm or less, and preferably has an average particle diameter of 5 μm or less from the viewpoint of adhesiveness, solder heat resistance and dispersibility.

In the composition of the present invention, (A)
The mixing ratio of each component of (E) is a weight ratio (in terms of solid content) shown below. (B) / (A) = 0.01 to 0.25 (C) / (A) = 1.0 to 4.0 (D) / (A) = 0.3 to 1.1 (E) / ( A) = 0.4 to 2.0 In this compounding ratio, by setting the ratio of (B) / (A) in the above range, high adhesive strength and solder heat resistance can be obtained, and flowability to the land portion can be obtained. Can also be suppressed. Further, by setting the ratio of (C) / (A) in the above range, high adhesive strength and solder heat resistance can be obtained. Further, by setting the ratio of (D) / (A) in the above range, good flame retardancy and adhesive strength can be obtained.
Furthermore, by setting the ratio of (E) / (A) within the above range, good flame retardancy and adhesive strength can be obtained, and B
Less coloring during staging. Further, the mixing ratio of each component is more preferably the following weight ratio (in terms of solid content). (B) / (A) = 0.03 to 0.15 (C) / (A) = 1.4 to 3.0 (D) / (A) = 0.5 to 0.9 (E) / ( A) = 0.6-1.4

The composition of the present invention may contain various stabilizers for the purpose of preventing oxidation or decomposition of the epoxy resin ((B) + (C)). Among various stabilizers, non-staining ones that do not cause coloring are preferable,
For example, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane (CiBa, Irganox 1)
010), 4,4'-methylene-bis (2,6-di-t
ert-butyl) phenol (manufactured by Shell Chem, Ionox 220), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene (Shell C
Hindered phenol-based stabilizers such as ionox 330, manufactured by Hem Co., and 4,4′-thiobis (6-tert)
-Butyl-3-methyl) phenol (manufactured by Ouchi Shinko Co., Ltd., Nocrack 300), 2,2′-thiobis (6-tert)
-Butyl-4-methyl) phenol (Aldrich)
And thiobisphenol-based stabilizers such as CAO-6) manufactured by Chem Co., Ltd .; and aliphatic thioester-based stabilizers such as dilauryl thiodipropionate (DLTP manufactured by Yoshitomi Pharmaceutical Co., Ltd.). The amount of these can be appropriately adjusted depending on the application. However, it is usually desirable to mix them within 5%, preferably 3%, in terms of solid weight, from the viewpoint of adhesive strength.

The preparation of the composition of the present invention comprises the steps (A) to (A)
The component (E), various stabilizers blended as required, and the curing agent (F) can be mixed at a predetermined ratio. The components are usually mixed together at the same time, or the components (D) and (E) are preliminarily mixed in a solvent and then mixed with other components.
A method of preparing a master batch of the component (D) and the component (E), followed by a pretreatment such as a method of mixing with other components, and then preparing a mixture of all the components, and a method of (A) to (E).
A method of preparing a composition by mixing the component and a mixture of various stabilizers, if necessary, and the curing agent (F) with another agent, for example, two liquids, mixing immediately before use, and providing the composition for use. Can be performed in accordance with These methods can be appropriately selected depending on the purpose of use of the composition of the present invention and the like.

As the (F) curing agent to be used, for example, conventional ones such as aliphatic polyamines, aromatic polyamines, imidazoles, polyamides, acid anhydrides, phenols, polymercaptans and boron trifluoride amine complexes Can be used.

The composition of the present invention can be usually dissolved in a solvent and applied to an adherend as a liquid adhesive. As the solvent used, for example, methyl ethyl ketone, methyl isobutyl ketone, dioxane, ethanol, methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, N-methylpyrrolidone, N, N-
Examples thereof include dimethylformamide, toluene, and xylene. Depending on the application, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio. Among these, methyl ethyl ketone, propylene glycol monomethyl ether, toluene, xylene, and N, N-dimethylformamide are preferred from the viewpoint of cost and solubility of each component of the composition.

The composition of the present invention comprises a polyimide film,
Flexible printed circuit board with excellent characteristics by applying to flexible printed circuit board made of polyester film, etc., forming into B-stage, and crimping to metal foil such as copper foil, aluminum foil by roll type or batch type press. Material can be obtained. Crimping temperature is 50-35
0 ° C., the pressing pressure is preferably in the range of 0.1 to 30 MPa, from the viewpoint of obtaining further excellent adhesive strength and solder heat resistance, the pressing temperature is 80 to 300 ° C., the pressing pressure is 0.5 to 20 MPa. It is particularly preferable to perform the reaction within the range.
Moreover, 80-350 degreeC, More preferably, 100-300.
When post-cured at ℃, the solder heat resistance can be further improved. A flexible printed wiring material produced by bonding a substrate and a metal foil through an adhesive layer made of the composition of the present invention, which is manufactured as described above, is a printed circuit board that requires flame retardancy, especially a flexible printed circuit board. Useful as a substrate material.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 (1) Preparation of Composition Carboxyl group-containing nitrile-butadiene rubber (Nipol 1072B, manufactured by Zeon Corporation, Mooney viscosity ML)
160 g of a 17% methyl ethyl ketone solution of _{1 + 4} (100 ° C .: 46), 4-functional N-glycidyl type epoxy resin (manufactured by Mitsubishi Gas Chemical Company, Inc., tetrad X, epoxy equivalent:
106 g / eq) 1.25 g, bisphenol A type solid epoxy resin (manufactured by Mitsui Chemicals, R301, epoxy equivalent:
475 g / eq) 50.0 g, resin-coated red phosphorus flame retardant (Nova Red 580C, manufactured by Rin Kagaku Co., Ltd.), average particle size:
20.0 g), 20.0 g of surface silane-treated aluminum hydroxide (manufactured by Nippon Light Metal Co., B1403-ST) and 120 g of methyl ethyl ketone were charged all at once into a 500 ml glass separable flask and stirred vigorously at room temperature for 1 hour. After completion of the stirring, the mixture was subjected to normal pressure filtration with a 325 mesh wire mesh filter to prepare a composition.

(2) Preparation of curing agent 7.0 g of 3,3'-diaminodiphenyl sulfone,
1.0 g of 4-diazabicyclo [5.4.0] 7-undecene (manufactured by Sun Abbott) and propylene glycol monomethyl ether (manufactured by Toho Chemical Co., Ltd., Hisolve M)
P) 42.0 g was charged all at once into a 100 ml glass flask and stirred vigorously at room temperature for 30 minutes. After completion of the stirring, the mixture was subjected to normal pressure filtration with a 325 mesh wire mesh filter to prepare a curing agent.

(3) Evaluation of Performance The composition / curing agent was mixed at a weight ratio of 7/1, shaken well for 1 minute, and then polyimide resin film (Kapton H, manufactured by Dupont Toray, thickness: 25 μm) An adhesive layer was formed on the upper surface by using an applicator (clearance: 200 μm). Next, the adhesive layer was dried in an oven at 130 ° C. for 3 minutes to make the adhesive layer B-stage. The B-staged adhesive layer was bonded to a matte surface of an electrolytic copper foil (thickness: 35 μm) and pressed at 1 MPa and 170 ° C. for 60 minutes to prepare a test piece of a flexible printed wiring material. The adhesiveness, solder heat resistance, heat aging resistance, flame retardancy, and flowability to the land portion of the prepared test piece were measured or evaluated by the following methods. Table 1 shows the results.

1) Adhesion: 90 ° peel strength and 180 ° peel strength (both of which were copper-coated) were measured in accordance with JIS C 6481. 2) Solder heat resistance: What is left for 12 hours under normal conditions (temperature 23 ° C., humidity 60%) in accordance with JIS C 6481,
After immersion in a solder bath at the temperature shown in Table 1 for 10 seconds, observation of swelling of the polyimide surface, and 90 °
The peel strength and the 180 ° peel strength (both coppered) were measured and used as indices of solder heat resistance. 3) Heat aging resistance: The test piece was immersed in a solder bath at the temperature and time shown in Table 1 to observe the presence or absence of discoloration on the surface of the polyimide film, and 90 ° peel strength and 180 ° peel strength (both are copper-coated). Was measured.

4) Flame retardancy: Evaluated according to the following criteria in accordance with UL Standard 94. V-0 (high)>V-1>V-2> HB (low) 5) Flowability to land: A hole having a diameter of 5 mm was formed in the test piece at the stage when the adhesive layer was B-staged. After that, it is bonded to electrolytic copper foil mat surface, 1MPa and 170 ℃
For 60 minutes, and the flow length of the adhesive flowing into the perforated portion was measured. 6) Coloring degree of B stage application surface: The B stage application surface was seen through and evaluated according to the following criteria. ○ The other side is visible × The other side is not visible △ The other side is faint

(Comparative Example 1) Instead of a tetrafunctional N-glycidyl type epoxy resin and a bisphenol A type solid epoxy resin, a low brominated bisphenol A type epoxy resin (R230M80, manufactured by Mitsui Chemicals, Inc., epoxy equivalent: 500 g)
/ Eq) in methyl ethyl ketone (solid content: 80%)
And using antimony trioxide (manufactured by Nippon Seiko Co., Ltd.
Production of a composition, preparation of a test piece, and evaluation of performance were performed in the same manner as in Example 1 except that PATOX-M) was added. Table 1 shows the results.

(Comparative Examples 2 and 3) The composition was the same as in Example 1 except that the mixing ratio of the tetrafunctional N-glycidyl type epoxy resin / carboxyl group-containing nitrile butadiene rubber was changed to the ratio shown in Table 1. Manufacture of a product, preparation of a test piece, and evaluation of performance were performed. Table 1 shows the results.

(Comparative Examples 4 and 5) A composition was prepared in the same manner as in Example 1 except that the mixing ratio of bisphenol A type solid epoxy resin / carboxyl group-containing nitrile-butadiene rubber was changed to the ratio shown in Table 1. Production, preparation of test pieces, and evaluation of performance were performed. Table 1 shows the results.

Comparative Examples 6 and 7 The procedure of Example 1 was repeated except that the mixing ratio of the resin-coated red phosphorus flame retardant / carboxyl group-containing nitrile-butadiene rubber was changed to the ratio shown in Table 1. Production of the composition, preparation of test pieces, and evaluation of performance were performed. Table 1 shows the results.

(Comparative Examples 8 and 9) The surface silane-treated aluminum hydroxide / carboxyl group-containing nitrile-butadiene rubber was mixed in the proportions shown in Table 1 except that
In the same manner as in Example 1, production of a composition, preparation of a test piece,
And the performance was evaluated. Table 1 shows the results.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

The flame-retardant adhesive composition of the present invention has excellent adhesive properties, solder heat resistance, heat aging resistance and flame retardancy, and is useful as an adhesive for flexible printed circuit boards.

Claims (2)

[Claims] (A) a carboxyl group-containing nitrile butadiene rubber, (B) a poly N-glycidyl type epoxy resin,
(C) a bifunctional or more epoxy resin having no N-glycidyl group, (D) a resin-coated red phosphorus flame retardant having an average particle diameter of 5 μm or less, and (E) a silane-treated Group 2 or A flame-retardant adhesive composition comprising a flame-retardant auxiliary comprising a Group 3 metal hydroxide in the following weight ratio (in terms of solid content): (B) / (A) = 0.01 to 0.25 (C) / (A) = 1.0 to 4.0 (D) / (A) = 0.3 to 1.1 (E) / ( A) = 0.4-2.0 2. An adhesive for a flexible printed circuit board, comprising the flame-retardant adhesive composition according to claim 1.