JPH08198907A - Ultraviolet polymerization type frame retardant tacky agent composition and flame retardant double-side tackey tape - Google Patents

Abstract

PURPOSE: To obtain an ultraviolet polymerization type flame retardant tacky agent composition, excellent in heat resistance and satisfying the specification of UL94 required for electrical and electronic equipment and a flame retardant double-side tacky tape using the tacky agent. CONSTITUTION: This ultraviolet polymerization type tacky agent composition comprises an alkyl (meth)acrylate monomer having a 4-14C alkyl group, a monofunctional monomer copolymerizable with the alkyl (meth)acrylate monomer, a polyfunctional oligoacrylate having >=300 molecular weight, an aromatic flame retardant in which the aromatic ring is brominated, antimony trioxide and a photopolymerization initiator. Furthermore, this flame retardant double- side tacky tape is obtained by coating a release substrate with the tacky agent composition and polymerizing the tacky agent composition with ultraviolet rays.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to a UV-polymerizable flame-retardant pressure-sensitive adhesive composition and a layer comprising the UV-polymerizable flame-retardant pressure-sensitive adhesive composition formed on a release substrate, which is polymerized by irradiating it with UV rays. Regarding double-sided adhesive tape.

[0002]

2. Description of the Related Art It is well known to use bromine-based, chlorine-based, phosphorus-based compounds and inorganic flame retardants for flame-retarding polymer materials. This technique is also commonly used for flame retarding acrylic pressure-sensitive adhesives. The brominated flame retardants include brominated aliphatic, alicyclic and aromatic compounds. Chlorine flame retardants include chlorinated products such as chlorinated paraffin and chlorinated polyethylene. As the phosphorus-based flame retardant, a phosphoric acid ester or a phosphoric acid ester containing halogen is used. The halogen-based flame retardant containing bromine or chlorine can be improved in flame retardancy by using an inorganic filler such as aluminum hydroxide together.
As a method for making an acrylic pressure-sensitive adhesive flame-retardant, a flame-retardant agent is generally dissolved or dispersed in an acrylic pressure-sensitive adhesive solution. This flame-retardant-containing pressure-sensitive adhesive solution is applied onto a substrate to produce a flame-retardant pressure-sensitive adhesive tape.

[0003]

SUMMARY OF THE INVENTION In an acrylic pressure-sensitive adhesive solution in which a flame retardant is dissolved or dispersed, the flame retardant easily precipitates.
It is difficult to apply the pressure-sensitive adhesive evenly, and the flame retardancy of the obtained pressure-sensitive adhesive tape varies widely. On the other hand, when a flame-retardant acrylic pressure-sensitive adhesive solution is applied and dried, foaming easily occurs, so that it is difficult to obtain a flame-retardant double-sided adhesive tape having a thickness of 200 μm or more and having a clean appearance. Halogen compounds are easily decomposed when exposed to light. When the halogen-based flame retardant is decomposed, it prevents the curing reaction of the pressure-sensitive adhesive, acts as a cross-linking agent to reduce the adhesiveness, and causes yellowing of the pressure-sensitive adhesive. Since flame retardants such as aliphatic compounds of bromine or chlorine and phosphorus compounds inhibit UV polymerization, the UV-polymerizable pressure-sensitive adhesive composition containing these flame retardants does not polymerize even when irradiated with UV light. Therefore, the obtained adhesive tape is highly sticky, has no heat resistance, and yellows and deteriorates in a short time when exposed to high temperatures.

[Object of the Invention] An adhesive tape having a thickness of 200 μm or more, which satisfies the UL94 standard required for electric and electronic devices and is excellent in heat resistance and adhesive strength, is obtained.

[0005]

[Means for Solving the Problems] As a result of intensive research to obtain an excellent UV-polymerizable flame-retardant pressure-sensitive adhesive, an aromatic bromine compound is stable to UV rays and contains (meth) acrylic acid alkyl ester monomer as a main component. Even if it is blended in the UV-polymerizable pressure-sensitive adhesive composition, it does not suppress the photopolymerization reaction and tends to accelerate the reaction, showing excellent adhesion without acting as a crosslinking agent for the pressure-sensitive adhesive. We found that it did not turn yellow.

(Meth) acrylic acid alkyl ester monomer having an alkyl group having 4 to 14 carbon atoms, monofunctional monomer copolymerizable with this (meth) acrylic acid ester monomer, and polyfunctional oligoacryl acrylate having a molecular weight of 300 or more. −
An aromatic flame-retardant having an aromatic ring brominated and antimony trioxide are added to an ultraviolet-polymerizable pressure-sensitive adhesive composition composed of a photopolymerization initiator and a photopolymerization initiator.

As an aromatic brominated flame retardant, hexabromobenzene is used as a basic skeleton, and a polyphenyl derivative is effective. All phenyl groups forming the polyphenyl derivative are brominated. For example, hexabromobenzene, decabromodiphenyl oxide, decabromodiphenylethane, etc. can be mentioned.

Since these flame retardants are not decomposed by irradiation of ultraviolet rays to the extent that they polymerize the ultraviolet-ray-curable pressure-sensitive adhesive composition, the pressure-sensitive adhesive tape obtained by UV-polymerization does not yellow and has excellent pressure-sensitive adhesive properties. It is a thing. Even with brominated aromatic flame retardants, adhesive tape made by using tetrabromobisphenol A
When turned on, it turns yellow and the tackiness of the adhesive disappears. Tris (2,3 dibromopropyl), an aliphatic brominated flame retardant
The pressure-sensitive adhesive composition containing isocyanurate or the like has a high ultraviolet curing rate, but the cured tape turns yellow when heated and loses its adhesiveness.

Since the above-mentioned brominated aromatic flame retardant is hardly dissolved in (meth) acrylic acid ester monomers, etc., the brominated aromatic flame retardant should be made into fine powder of 10 μm or less as much as possible (meth) acrylic acid ester. It is necessary to disperse well in a pressure-sensitive adhesive composition containing a monomer as a main component. 10
Brominated aromatic flame retardants up to μm are commercially available. The brominated aromatic flame retardant is used in an amount corresponding to 10 to 30 parts by weight of bromine based on 100 parts by weight of the flammable component of the pressure-sensitive adhesive composition. Further, when the antimony trioxide powder is used in combination with 5 to 20 parts by weight based on 100 parts by weight of the flammable component of the pressure-sensitive adhesive composition, the flame retardant effect is promoted.

The adhesive composition is a prepolymerized prepolymer.
A brominated aromatic flame retardant and antimony trioxide are mixed with.
Since it is difficult to disperse the flame retardant and antimony trioxide in the prepolymer, it is necessary to sufficiently disperse them using an impact type high speed disperser (nanomizer). The pressure-sensitive adhesive tape made from the pressure-sensitive adhesive composition in which the flame retardant is not evenly dispersed has uneven flame retardancy, and the appearance cannot be uneven. Therefore, in the present invention, the flame retardant and antimony trioxide are dispersed as follows.
The viscosity of the prepolymer (prepolymer) is 1200 to 250.
Set to 0 cps. The flame retardant and antimony trioxide are wetted with the same weight of the monomer and then blended. Because it is difficult to disperse with stirring with a rotating blade. An impact type high speed disperser (nanomizer) is used. In order to impart thixotropy, 2 to 7 parts by weight of finely powdered silica is added per 100 parts by weight of the prepolymer.

The (meth) acrylic acid alkyl ester having an alkyl group having 4 to 14 carbon atoms includes butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, 3,5,5 trimethylhexyl. It may be selected from (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobonyl (meth) acrylate, ethoxy (meth) acrylate, butoxy (meth) acrylate, phenoxy (meth) acrylate and cyclohexyl (meth) acrylate.

At least one monomer selected from the following groups is used as the monomer having a copolymerizable ethylenically unsaturated bond group. (Meth) acrylic acid, 2-hydroxyethyl (meth)
Acrylate, 2-hydroxyethyl (meth) acrylate
2-hydroxypropyl (meth) acrylate, 2-
A group consisting of monomers having a polar group such as hydroxypropyl (meth) acrylate and glycidyl (meth) acrylate.

A group consisting of oligoester acrylates such as nonylphenoxypolyethylene glycol acrylate and nonylphenoxy polypropylene glycol acrylate.

The polyfunctional oligoacrylate having a molecular weight of 300 or more contains 10 or more carbons between vinyl groups.
For example, Ennea ethylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-400, etc.),
Tetradeca ethylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-600, etc.) polyalkylene glycol diacrylate, ethylene oxide-modified bisphenol A diacrylate (Kyoeisha Oil and Fat Chemical Co., Ltd. BP-4EA, etc.), propylene oxide-modified bisphenol A diacrylate (manufactured by Kyoeisha Oil & Fat Chemical Co., Ltd., BP4PA, etc.), ethylene oxide modified trimethylol propane triacrylate (manufactured by Kyoeisha Oil & Fat Chemical Co., Ltd., TPM-6EO-3A), hydroxypivalic acid neopentylglycol diacrylate (Nippon Kayaku Co., Ltd., KAYARAD MANDA, etc.)
And its derivatives (KAYARAD manufactured by Nippon Kayaku Kogyo Co., Ltd.)
HX-220, KAYARAD HX-620, etc.) and the like. Further, oligoester acrylate and oligourethane acrylate can also be used.

The photopolymerization initiator is most preferably an acetophenone-based or benzoin-based one, for example, generally commercially available 4-phenoxydicycloacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-. Examples thereof include 2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin isobutyl-terl, benzyl dimethyl ketal, and mixtures thereof.

[0016]

EXAMPLES Hereinafter, specific examples will be described. [Example 1] 9 kg of 2-ethylhexyl acrylate,
Photopolymerization initiator 2-hydroxy 2-methyl-1-phenylpropane 1-on a mixed monomer consisting of 1 kg of acrylic acid
Ong (Darocur 1173, manufactured by Merck Ltd.) was dissolved in an amount of 1.5 g. This monomer mixture solution was placed in a photopolymerization device having a shutter mechanism, and nitrogen gas was blown into the photopolymerization device to perform nitrogen substitution. Then, the temperature of the monomer mixture is set to 30 ° C.
Then, the ultraviolet rays were irradiated for 10 seconds while stirring, and the shutter was operated to stop the irradiation. The temperature of the monomer mixture immediately began to rise, reaching 30.5 ° C after about 30 seconds. After that, irradiation for 5 seconds and stop for 30 seconds are repeated,
A prepolymer having a viscosity of 1800 cps at 0 ° C was produced.

[Preparation of pressure-sensitive adhesive composition] 4.5 kg of 2-ethylhexyl acrylate monomer and 0.5% of acrylic acid
4 kg of hexabromobenzene (AFR-1001 Asahi Glass Co., Ltd.) having an average particle size of 7 μm was added to the prepolymer of kg.
g and 1 kg of antimony trioxide powder were added and dispersed in a paste form. Furthermore, 5 kg of a prepolymer and a neopentyl diacrylate hydroxypivalate [K] having a molecular weight of 312
AYARAD MANDA], 20 g, photopolymerization initiator 2
15 g of -hydroxy-2-methyl-1-phenylpropan-1-one [Darocur 1173] was added and stirred, and then hexabromobenzene and antimony trioxide were sufficiently dispersed by an impact type disperser (nanomizer) to obtain an ultraviolet polymerization type. A flame-retardant pressure-sensitive adhesive composition was obtained.

[Production of Adhesive Tape] An adhesive tape was produced in the following manner using the above-mentioned UV-polymerizable flame-retardant adhesive composition. First, a transparent PET film having a thickness of 50 μm, both sides of which were subjected to a peeling treatment with silicone, was used as a base for a peeling sheet, and a UV-polymerizable flame-retardant adhesive composition having a thickness of about 0.4 mm was prepared. The thing was applied. Furthermore, a transparent PET film having a thickness of 50 μm, one surface of which was peeled off with silicone, was placed thereon and compressed between two rolls to give a uniform pressure-sensitive adhesive composition layer of 0. A 4 mm laminate was obtained.

Next, an insect trap fluorescent lamp (main wavelength 352n)
m, 0.44 mW / cm ² ) are arranged at intervals of 60 mm, and a height of about 2.00 mW /
In an irradiation furnace that is capable of irradiating with cm ² of ultraviolet rays,
The laminate was exposed to UV light for 60 seconds. Further, using a high-pressure mercury lamp (main wavelength 365 nm, output 80 W / cm), ultraviolet rays were irradiated for 30 seconds at an irradiation intensity of 35.5 mW / cm ² for curing. 50μ with peeling treatment on one side
An adhesive tape having a thickness of 0.4 mm was obtained by peeling off the m PET film.

The resulting adhesive tape was evaluated as follows. (1) Measurement of polymerization rate About 1 g of an adhesive tape was precisely weighed, and 2 at 120 ° C. and 5 mmHg.
The polymerization rate was calculated by regarding the weight reduction amount after standing for a while as the unreacted monomer amount. As a result, a result of 99.5% was obtained.

(2) Evaluation of UL94 flammability An adhesive tape cut into a size of 13 mm in width and 130 mm in length was used as a sample and evaluated according to the UL94 standard.
As a result, an adhesive tape satisfying the UL94V0 ability was obtained.

(3) Stability Test of Adhesive Tape The adhesive tape was cut into a size of 50 mm × 50 mm,
It was left in an air circulation oven at 150 ° C. for 1 hour and the degree of discoloration was observed. As a result, yellowing did not occur compared to the initial stage.

(4) Measurement of heat-resistant holding power The heat-resistant holding power was measured according to the method of measuring the holding power of JIS Z 0237. In this case, as the adherend, a 2 mm-thick stainless steel plate polished with No. 280 water-resistant polishing paper and a thickness of 0.05 mm
Of aluminum foil was used. The adhesive area between the adhesive and the stainless steel plate as the adherend is 25 × 25 mm, and the area for the aluminum foil is 25 mm × 50 mm or more.
The area of adhesion to the stainless steel plate was reduced so that it would be displaced when a load was applied from the stainless steel plate. The measurement evaluated the heat resistance retention at 180 degreeC of the surface of the adhesive tape irradiated with ultraviolet rays. The shift distance after 1 hour under a load of 1 kg was 0.1 mm.

(5) Measurement of Adhesive Strength As the adherend, a thickness of 2 which was polished with No. 280 water-resistant abrasive paper
A stainless steel plate having a size of 30 mm, a width of 30 mm, and a length of 120 mm was used. After cutting the adhesive tape to a width of 20 mm and a length of 100 mm and lightly adhering it to an adherend, a 50 μm thick aluminum foil cut into a width of 30 mm and a length of 200 mm was used as a backing material and a load of about 2 kg. -Law was reciprocated once to bond. After the adhesion, the aluminum foil was left at 23 ° C. for 48 hours and peeled off at a peeling speed of 300 mm / min in the 90 ° direction to obtain a peel strength of 4.8 kgf / cm.

Examples 2 to 5 Hexabromobenzene used in Example 1 (AFR-1001 Asahi Glass Co., Ltd.)
Manufactured) and the amount of antimony trioxide were changed as shown in Table 1, an adhesive tape was prepared in the same manner as in Example 1, and the evaluation results are also shown in Table 1.

Example 6 The hexabromobenzene (AFR-1001) used in Example 1 was replaced with decabromodiphenyl oxide (AFR-1021 Asahi Glass Industry Co., Ltd.).
A pressure-sensitive adhesive tape was manufactured and evaluated in exactly the same manner as in Example 1 except that it was changed to "made". The results are also shown in Table 1.
It was shown to. Example 7 Instead of hexabromobenzene (AFR-1001) used in Example 1, decabromodiphenylethyl (manufactured by Cytex Ethyl Corporation).
An adhesive tape was produced and evaluated in the same manner as in Example 1 using. The results are also shown in Table 1.

Comparative Example 1 A pressure-sensitive adhesive composition containing no flame retardant and antimony trioxide was prepared using the prepolymer prepared in Example 1, and an adhesive tape was prepared in the same manner as in Example 1. Obtained. When the flammability test of this adhesive tape was conducted according to UL94, it burned.

[Comparative Example 2] Instead of hexabromobenzene (AFR-1001) used in Example 1,
Using an aliphatic brominated flame retardant (tris (2,3-dibromopropyl) isocyanurate, a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 and irradiated with ultraviolet rays to produce a pressure-sensitive adhesive tape. As a result, the adhesive tape turned yellow by irradiation with ultraviolet rays, and when left in an air-circulation oven at 150 ° C for 1 hour, it turned yellow remarkably, which is suitable for practical use. No tacky tape was obtained.

Comparative Example 3 An adhesive tape was obtained in the same manner as in Example 1, except that chlorinated paraffin (Salt Para 70, chlorine content 70%, Ajinomoto Co., Inc.) was used as a flame retardant. The obtained adhesive tape has turned yellow by irradiation with ultraviolet rays,
The adhesiveness was also poor, and this was not practical either.

Comparative Example 4 An adhesive tape was obtained in the same manner as in Example 1 except that chlorinated phosphoric acid ester (CR900, chlorine content 70.7%, Daihachi Chemical Co., Ltd.) was used as a flame retardant. As a result, the obtained adhesive tape turned yellow by irradiation with ultraviolet rays and had poor adhesiveness.

COMPARATIVE EXAMPLE 5 Aromatic tetrabromobisphenol A (bromine content 58.8% A as a flame retardant)
FR-1010 Asahi Glass Co., Ltd. was used. Example 1
A pressure-sensitive adhesive composition was produced in the same manner as in Example 1. However, in order to adjust the bromine content in the pressure-sensitive adhesive composition to that of Example 1, AFR-1 was used.
6 kg of 010 was blended. The adhesive tape produced by irradiating ultraviolet rays in the same manner as in Example 1 had a polymerization rate of 99.0.
%, Did not conform to UL94V0. Poor adhesiveness due to the large amount of flame retardant compounded, and adhesive strength of 1.2 kgf / cm
It was very small, and turned yellow when it was kept in an air circulation oven at 150 ° C for 1 hour.

[0032]

As is apparent from the above description, the electric power
Flame-retardant grade UL of polymeric materials used in electronic equipment
A solventless pressure-sensitive adhesive composition satisfying 94V0 and a pressure-sensitive adhesive tape can be obtained. The adhesive tape has excellent heat resistant cohesive strength. Further, it has a high adhesive strength and can be used for bonding structural members. Since it is a solventless adhesive, a thick adhesive tape can be obtained. Since it is a UV-curable and solvent-free pressure-sensitive adhesive, it is possible to manufacture an inexpensive pressure-sensitive adhesive tape with little environmental pollution.

[Table 1]

Claims (6)

[Reference number] SCP940040 [Claims] 1. A (meth) acrylic acid alkyl ester,
It is characterized in that a flame retardant having an aromatic ring brominated and antimony trioxide are blended in a UV-polymerizable pressure-sensitive adhesive composition comprising a compound containing a copolymerizable ethylenically unsaturated bond group and a photopolymerization initiator. A UV-curable flame-retardant pressure-sensitive adhesive composition comprising: 2. A (meth) acrylic acid alkyl ester,
40 to 100 parts by weight of a flame retardant having an aromatic ring brominated and 5 to 20 parts by weight of antimony trioxide based on 100 parts by weight of a compound containing an ethylenically unsaturated bond group copolymerizable therewith. The ultraviolet-curable flame-retardant pressure-sensitive adhesive composition according to claim 1, wherein 3. The ultraviolet-curable pressure-sensitive adhesive composition according to claim 1, wherein the alkyl group of the (meth) acrylic acid alkyl ester has 4 to 14 carbon atoms. 4. The ultraviolet-polymerizable pressure-sensitive adhesive composition according to claim 1, wherein the compound containing an ethylenically unsaturated bond group contains a polyfunctional oligoacrylate having a molecular weight of 300 or more. 5. The ultraviolet-curable pressure-sensitive adhesive composition according to claim 1, wherein the polyfunctional oligoacrylate having a molecular weight of 300 or more is hydroxypivalic acid neopentylglycol diacrylate. 6. A double-sided pressure-sensitive adhesive tape obtained by polymerizing the pressure-sensitive adhesive composition according to claim 1 formed on a release substrate with ultraviolet rays. [0001]