JPH0632841A - Polymerizable composition and viscoelastic products - Google Patents

Abstract

PURPOSE:To provide an acrylic polymer composition having excellent adhesive performance such as adhesion and cohesive force at elevated temperatures as well as flame retardancy, and viscoelastic products therefrom. CONSTITUTION:This polymerizable monomer composition comprises (a) 35 to 80wt.% of one or more acrylate monomers selected from (meth)acrylic acid esters having one or more bromine atoms in one molecule, (b) 20 to 65wt.% of at least one of acrylate monomers selected from (meth)acrylic acid esters having a phosphate group and (c) 0 to 40wt.% of at least one of acrylate monomers selected from (meth)acrylic alkyl esters having 1 to 12 C alkyl group.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant acrylic polymerizable composition and a viscoelastic product obtained from the composition.

[0002]

BACKGROUND ART Viscoelastic products made of acrylic polymers include, for example, adhesives, adhesive tapes, adhesive sheets,
Adhesive processed products such as double-sided adhesive tape and sealants can be mentioned. Acrylic pressure-sensitive adhesives are mainly composed of acrylic polymers, so they have excellent light resistance, weather resistance, oil resistance, etc.Acrylic pressure-sensitive adhesive tapes based on plastic film or paper It is used in a wide range of fields due to its excellent adhesiveness such as strength and cohesive strength, and aging resistance such as heat resistance and weather resistance.

Taking typical acrylic adhesive tapes as these acrylic viscoelastic products, the adhesives used are generally composed of an alkyl acrylate ester and a vinyl monomer copolymerizable therewith. It is produced by a method of thermal polymerization in a solvent or a method of emulsion polymerization in a water system.

The above acrylic pressure-sensitive adhesive can exhibit cohesive force at high temperature by being crosslinked by a crosslinking agent, but since the pressure-sensitive adhesive component is composed of a flammable compound, it has flame retardancy. There is a problem that it cannot be used in the required fields. Examples of fields in which flame retardancy is required include building materials, vehicles, electronic devices, aircraft, ships and the like. Specifically, a double-sided pressure-sensitive adhesive tape for fixing a carpet of an aircraft is required to have sufficient tackiness and self-extinguishing property to extinguish fire instantly.

The pressure-sensitive adhesive used in the flame-retardant pressure-sensitive adhesive tape includes, for example, a pressure-sensitive adhesive base polymer such as an acrylic polymer or synthetic rubber, and a known flame-retardant such as aluminum hydroxide, paraffin chloride, antimony trioxide and the like. The added technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-223187.

However, according to the above technique, the flame retardant effect cannot be obtained unless a large amount of the flame retardant is added, and when added in a large amount, the adhesive physical properties are significantly lowered, or the flame retardant is separated over time. There is a problem that the flame retardant effect is reduced.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to have excellent adhesive performance such as adhesive strength and cohesive strength at high temperature and to have flame retardancy. An object is to provide an acrylic polymerizable composition and a viscoelastic product.

[0008]

The polymerizable composition of the first invention comprises at least one or more selected from (meth) acrylic acid esters having (a) one or more bromine atoms in one molecule in the monomer composition. Acrylate-based monomer 35-80
% By weight, (b) 20 to 65% by weight of at least one acrylate monomer selected from (meth) acrylic acid ester having a phosphate group, and (c) (meth) acrylic alkyl alcohol having 1 to 12 carbon atoms. It is characterized by containing 0 to 40% by weight of at least one acrylate-based monomer selected from acid esters. The viscoelastic product of the second invention is characterized by being produced by copolymerizing the polymerizable composition according to claim 1. The viscoelastic product of the third invention is obtained by applying a photopolymerizable composition obtained by further mixing the polymerizable composition according to claim 1 with a photopolymerization initiator on a substrate, and then irradiating the composition with ultraviolet rays. It is characterized by being made. From the above, the above object is achieved.

The first invention will be described in detail below.
The acrylate-based monomer (a) used in the first invention has at least one bromine atom in one molecule (meth).
An acrylic acid ester, and examples thereof include ethylene oxide (hereinafter referred to as EO) -modified tribromophenol (meth) acrylate, tribromophenol 3EO-added (meth) acrylate, and 2,6-dibromo-4-t-butylphenyl acrylate. To be The above monomers can be used alone or in combination of two or more kinds.

In the polymerizable composition of the first invention, when the amount of the acrylate-based monomer (a) decreases, the flame retardancy decreases, and when the amount of the acrylate monomer (a) increases, the tackiness of the viscoelastic product obtained decreases. Limited to ~ 80% by weight.

The acrylate-based monomer (b) used in the first invention is a (meth) acrylic acid ester having a phosphate group, for example, mono [2-
(Meth) acryloyloxyethyl] acid phosphate, 3-chloro-2-acidphosphooxypropyl (meth) acrylate, diphenyl-2- (meth) acryloyloxyethylphosphonate, dibutyl-2- (meth) acryloyloxy Examples include ethylphosphonate, dioctyl-2- (meth) acryloyloxyethylphosphonate, and the like. The above monomers can be used alone or in combination of two or more kinds.

In the polymerizable composition of the first invention, when the amount of the acrylate-based monomer (b) is small, it becomes difficult to form a carbonized layer at the time of ignition and the flame retardancy is lowered, and when the amount is large, the tackiness of the viscoelastic product is increased. Is reduced, so that it is limited to 20 to 65% by weight in the monomer composition.

The acrylate-based monomer (c) used in the first invention is a (meth) acrylic acid ester of an alkyl group having 1 to 12 carbon atoms, preferably an alkyl alcohol having 4 to 12 carbon atoms. N-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth)
Examples thereof include isononyl acrylate. These monomers may be used alone or in combination of two or more.

When the number of carbon atoms of the above-mentioned alkyl alcohol increases, the tackiness decreases, so the number of carbon atoms is limited to 12 or less. In the polymerizable composition of the first invention, when the amount of the acrylate-based monomer (c) increases, the flame retardancy is impaired, so the content is limited to 40% by weight or less in the monomer composition.

In the polymerizable composition of the first invention, in addition to the acrylate-based monomers (a), (b) and (c), a vinyl-based monomer copolymerizable with these acrylate-based monomers may be added. . Examples of such vinyl-based monomers include (meth) acrylic acid, acrylamide, (meth) acrylonitrile, N-substituted acrylamide, hydroxyethyl (meth) acrylate,
Examples include monomers such as carboxyethyl acrylate, N-vinylpyrrolidone, maleic acid, itaconic acid, and N-methylol acrylamide. Particularly preferable among these vinyl-based monomers are acrylic acid, carboxyethyl acrylate and N-vinylpyrrolidone. These vinyl-based monomers not only enhance the adhesive performance but also have the action of promoting the reaction.

Further, in addition to the vinyl-based monomer, a vinyl-based monomer that forms a polymer having a low glass transition point,
For example, tetrahydrofurfuryl acrylate, benzyl acrylate, cyclohexyl acrylate, isobornyl acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, fluorine acrylate, silicon acrylate and the like can be used.

The vinyl monomer copolymerizable with these acrylate-based monomers is blended in an amount of 40 to 0% by weight with respect to 60 to 100% by weight of the acrylate-based monomer composition [(a) + (b) + (c)]. To be done. When the amount of the vinyl-based monomer exceeds 40% by weight, the adhesive property as an acrylic adhesive is deteriorated, which is not preferable.

Next, the second invention will be described below.
The polymerizable composition used in the second invention is the same monomer composition as that used in the first invention, and has acrylate monomers (a), (b) and (c) as constituent components.

A thermopolymerization initiator such as a peroxide compound or an azobis compound is added to the above polymerizable composition and copolymerized to obtain a viscoelastic product such as an adhesive solution or a sealing material. A cross-linking agent such as an aziridine-based, isocyanate-based, epoxy-based or melamine-based agent may be added to the viscoelastic product thus obtained in order to further impart cohesive force.

Next, the third invention will be described below.
The polymerizable composition used in the third invention is the same monomer composition as used in the first invention, and contains acrylate monomers (a), (b) and (c) as constituent components.

The above-mentioned polymerizable composition preferably contains the following polymerizable cross-linking agent. By the addition of the following polymerizable cross-linking agent, cross-linking occurs between polymer molecules in the course of the photopolymerization reaction, for example, when the polymerizable composition is used as a pressure-sensitive adhesive, its heat resistance is improved, aggregation at high temperature Strength and holding power are improved.

Examples of such a polymerizable cross-linking agent include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di ( (Meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, other epoxy acrylate, polyester acrylate, urethane acrylate, etc. be able to.

When the amount of the polymerizable cross-linking agent is too large, it becomes difficult to control the degree of cross-linking. Therefore, the amount of the acrylate-based monomer composition [(a) + (b) + (c)] is 100 parts by weight. It is preferably 5 parts by weight or less.

The photopolymerizable composition used in the third invention is
A photopolymerization initiator is added to the above polymerizable composition. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone [manufactured by Merck & Co., product name "Darocur 29
59 "], 2-hydroxy-2,2-dimethylacetophenone [manufactured by Merck, trade name" Darocur 117
3 ”], acetophenone initiators such as methoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; benzoin ether initiators such as benzoin ethyl ether and benzoin isopropyl ether; ketal initiators such as benzyl dimethyl ketal; ,
Examples thereof include halogenated ketones, acylphosphinoxides, acylphosphonates and the like.

When the amount of the above-mentioned photopolymerization initiator is small, the photopolymerization initiator is consumed by the light energy at the initial stage of the polymerization, so that the unreacted monomer is liable to remain and the resulting polymer has a monomer odor. Not only does the cohesive force decrease, and conversely, if it increases, the polymerization reaction rate increases, but the dispersion of the molecular weight of the obtained polymer increases and the adhesive performance decreases, so the acrylate-based monomer composition 1
A range of 0.1 to 5 parts by weight is preferable with respect to 00 parts by weight.

If desired, the photopolymerizable composition may further contain commonly used additives such as a thickener, a thixotropic agent, a filler and a filler.

Examples of the thickener include acrylic rubber,
Epichlorohydrin rubber, isoprene rubber, butyl rubber, etc. are used, and as the thixotropic agent, for example,
Colloidal silica, polyvinylpyrrolidone, etc. are used.

As the filler, for example, calcium carbonate, clay and the like are used, and as the filler, inorganic hollow bodies such as glass balloons, alumina balloons and ceramic balloons; organic beads such as nylon beads, acrylic beads and silicon beads. Body: organic hollow body such as vinylidene balun chloride, acrylic balun; monofilament such as polyester, rayon and nylon.

A viscoelastic product can be obtained by irradiating the photopolymerizable composition with light such as ultraviolet rays. To obtain a polymer from the photopolymerizable composition, usually, in order to remove dissolved oxygen in the composition, it is purged with an inert gas such as nitrogen gas, or phenyldiisodecyl phosphite or triisodiate is used. A compound having an oxygen removing effect such as decyl phosphite and stannous octoate is added.
By adding such a compound, sufficient polymerization (curing) can be realized even if the oxygen concentration in the atmosphere is high to some extent.

In the case of producing an adhesive tape as a viscoelastic product, for example, the photopolymerizable composition is applied onto a release paper or the like, or a plastic film, paper, cellophane, cloth, non-woven fabric, metal foil or the like is used. Coating or impregnating the substrate. In addition, as a viscoelastic product, for example, when a sealing material is manufactured, the photopolymerizable composition is injected into a peelable elongated mold or the like.

When coating, impregnating or injecting the above-mentioned photopolymerizable composition onto a substrate, a mold or the like, it is preferable to thicken with a thickener so that the work can be carried out smoothly. As another thickening method, for example, there is a method of preliminarily polymerizing a part of the monomer component by irradiating a small amount of ultraviolet rays. For these coating, impregnating or pouring operations, a device devised so as not to come into contact with air (oxygen) is required.

After coating, impregnating or pouring on a mold or substrate,
The photopolymerizable composition is passed through a box replaced with an inert gas, and irradiation with light such as ultraviolet rays or visible light is performed through quartz glass, Pyrex glass, or borate glass.

By covering the surface of the photopolymerizable composition applied, impregnated or injected on the substrate or the mold with a polyester film having releasability, even in an inert gas atmosphere, Light irradiation may be performed while preventing contact with air. In this case, it is preferable to add the compound having the oxygen removing effect.

Ultraviolet rays from an ultraviolet lamp are usually used for irradiation of light. As an ultraviolet lamp, the light wavelength is 300
A lamp having a spectral distribution in the region of up to 400 nm is used.
Ultra high pressure mercury lamps, metal halide lamps, microwave excited mercury lamps, etc. are used. Of these, the former two lamps are used to obtain a relatively low light intensity,
The latter five lamps are used to obtain a relatively high light intensity.

Generally, the light intensity is preferably about 0.5 to 100 mW / cm ² by adjusting the distance to the object to be irradiated and the voltage. It is preferable that the polymerization reaction is substantially completed at the time when the residual monomer becomes about 0.5% by weight or less at the above light intensity.

In the present invention, a tackifying resin (tackifier) may be added as long as the object of the present invention is not impaired. As the tackifying resin used here, for example, rosin-based resin, modified rosin-based resin,
Examples include terpene resin, terpene phenol resin, aromatic modified terpene resin, C ₅ and C ₉ petroleum resin, and coumarone resin.

A flame retardant such as antimony trioxide may be added to the polymerizable composition used in the present invention in order to impart higher flame retardancy.

[0038]

EXAMPLES Next, examples and comparative examples of the present invention will be described, but the present invention is not limited to these. (Example 1) [Preparation of polymerizable composition] EO-modified tribromophenol acrylate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name "BR3"
1 ") 50 parts by weight, diphenyl-2-methacryloyloxyethyl phosphate (manufactured by Daihachi Chemical Co., Ltd., trade name" M ")
R260 ") 35 parts by weight, 2-ethylhexyl acrylate 15 parts by weight, hexanediol diacrylate 0.
07 parts by weight and 1 part by weight of a photopolymerization initiator (“Darocur 2959” manufactured by Merck & Co., Inc.) were stirred and mixed until uniform to obtain a polymerizable composition.

[Preparation of Viscoelastic Product] The above polymerizable composition was applied onto an imide film having a thickness of 100 μm in a thickness of 35 μm.
coated with a comma coater to an oxygen concentration of 30
An ultrahigh pressure mercury lamp was used as a light source in an inert zone of 0 ppm, and the light intensity of the irradiation surface was 8 mW / cm ² [365n
m as the intensity value measured with a light intensity meter UVR-1 (manufactured by Tokyo Optical Machinery Co., Ltd.) having the maximum sensitivity], and then irradiated for 3 minutes to carry out a polymerization reaction to perform flame-retardant adhesion. A tape (a viscoelastic product) was produced. The amount of residual monomers in the pressure-sensitive adhesive layer of the obtained flame-retardant pressure-sensitive adhesive tape was 0.2% by weight.
It was below.

[Physical Property Test of Adhesive Tape] The following physical property tests were conducted using the above flame-retardant adhesive tape as a sample, and the measurement results are shown in Table 1. (1) SP Adhesiveness In accordance with JIS Z0237, the above sample was laminated on a stainless steel plate with a width of 25 mm, and then the SP adhesiveness was measured by a 180-degree peeling method. (2) Shear retention force In accordance with JIS Z0237, the above sample was attached on a stainless steel plate with an adhesion area of 25 × 25 mm, and 10
After leaving it at 0 ° C. for 20 minutes, a weight of 1 kg was applied and the time until falling was measured. (3) Flame-retardant test According to JIS C2107, width 5mm x length 10c
After fixing one end of the test piece of m, the other end was ignited and the combustion state was observed.

Example 2 EO-modified tribromophenol acrylate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name "BR3"
1 ") 50 parts by weight, diphenyl-2-methacryloyloxyethyl phosphate (manufactured by Daihachi Chemical Co., Ltd., trade name" M ")
R260 ") 50 parts by weight, carboxyethyl acrylate 10 parts by weight, hexanediol diacrylate 0.0
7 parts by weight and a photopolymerization initiator (“Darocur 2 manufactured by Merck Ltd.
959 ") was stirred and mixed until 1 part by weight was obtained to obtain a polymerizable composition. A flame-retardant pressure-sensitive adhesive tape was produced from this polymerizable composition in the same manner as in Example 1, and then the same physical property test as in Example 1 was conducted. The results are shown in Table 1. The residual monomer amount in the pressure-sensitive adhesive layer of the obtained flame-retardant pressure-sensitive adhesive tape was 0.2% by weight or less.

Comparative Example 1 95 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of acrylic acid, 0.05 part by weight of hexanediol diacrylate, 1 part by weight of a photopolymerization initiator (“Darocur 2959” manufactured by Merck & Co.) and acrylic. 2 parts by weight of the rubber was mixed in the same manner as in Example 1 until it became uniform to obtain a polymerizable composition. From this polymerizable composition,
After producing a flame-retardant pressure-sensitive adhesive tape in the same manner as in Example 1, the same physical property test as in Example 1 was performed, and the results are shown in Table 1.
It was shown to. The amount of residual monomers in the pressure-sensitive adhesive layer of the obtained flame-retardant pressure-sensitive adhesive tape was 0.3% by weight or less.

[0043]

[Table 1]

[0044]

EFFECTS OF THE INVENTION According to the present invention, an acrylic polymerizable composition and a viscoelastic product having excellent adhesive properties such as adhesive force and cohesive force at high temperature and having flame retardancy are provided. The viscoelastic product is suitably used in fields requiring high flame retardancy, such as electrical insulating tapes and adhesive tapes for buildings used in environments where welding sparks are scattered.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C09J 133/16 JDE 7921-4J C09K 21/14 8318-4H

Claims (3)

[Claims] 1. In the monomer composition, (a) at least one or more acrylate-based monomer 3 selected from (meth) acrylic acid esters having at least one bromine atom in one molecule.
5 to 80% by weight, (b) 20 to 65% by weight of at least one acrylate monomer selected from (meth) acrylic acid ester having a phosphate group, and (c) an alkyl alcohol having 1 to 12 carbon atoms ( Meta)
A polymerizable composition comprising 0 to 40% by weight of at least one acrylate-based monomer selected from acrylic acid esters. 2. A viscoelastic product, which is produced by copolymerizing the polymerizable composition according to claim 1. 3. A photopolymerizable composition obtained by further mixing a photopolymerization initiator with the polymerizable composition according to claim 1, which is applied to a substrate and then irradiated with ultraviolet rays to be produced. A viscoelastic product characterized by being