JPH05247141A - Photopolymerizable composition, its polymer and its polymerization - Google Patents

Abstract

PURPOSE:To provide the subject new polymerizable composition containing a photopolymerization initiator, substantially not containing a solvent, useful for producing a viscoelastic product and capable of producing an acrylic viscoelastic product remarkably excellent in its productivity and exhibiting high-grade adhesivity. CONSTITUTION:The objective photopolymerizable composition contains (a) vinyl monomers composed mainly of an alkyl (meth)acrylate, (b) a vinyl monomer having <=0.45 Q value representing the Alfrey-Price monomer reactivity ratio and capable of providing its homopolymer exhibiting >=35 deg.C glass transition temperature and (c) a photopolymerization initiator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a (meth) acrylate type photopolymerizable composition. More specifically, the homopolymer has a glass transition temperature of 35 ° C. or higher and Alfrey and Pric.
The present invention relates to the compounding of a photopolymerizable composition containing a vinyl carboxylate monomer having a Q value of 0.45 or less, which indicates the monomer reactivity ratio of e, and a polymer obtained by irradiating it with light.

[0002]

2. Description of the Related Art Viscoelastic products made of acrylic polymers having excellent light resistance, weather resistance, oil resistance, etc., such as acrylic adhesives, acrylic adhesive tapes, acrylic adhesive sheets, double-sided adhesive tapes, foams. Well-known products such as adhesive processed products of the body.

Since the acrylic pressure-sensitive adhesive is mainly composed of an acrylic polymer, it is excellent in light resistance, weather resistance, oil resistance and the like, and the acrylic pressure-sensitive adhesive tape using a plastic film or paper as a surface base material. Is excellent in adhesive performance such as adhesive strength and cohesive strength and aging resistance such as heat resistance and weather resistance, and is therefore widely used.

Acrylic pressure-sensitive adhesive tapes, which are typical of these viscoelastic products, have hitherto been manufactured using a solution prepared by dissolving an acrylic pressure-sensitive adhesive in an organic solvent. However, this method consumes a large amount of energy to dry the pressure-sensitive adhesive solution coated or impregnated on the substrate at a high temperature, and requires a large-scale recovery device to prevent air pollution by the solvent. is there. Moreover, since the solvent easily catches fire, there is a danger of fire, and a sufficient safety device is required to maintain safety. For these reasons, there is an increasing demand to replace the method using the adhesive solution with another method.

As one of the methods, an adhesive is not separately prepared in a solvent and then made into a tape, but the acrylic monomer composition is radically polymerized by UV irradiation on the base material or the release material of the tape to form an adhesive. Then, there is a method of making a tape all at once.

This method began in 1961 with Belgian Patent No. 675,420. However, the adhesive produced by this method is inferior in cohesive strength, etc.
U.S. Pat. No. 4,181,752 by s) et al. uses a solvent-free photopolymerizable liquid composition in which a vinyl-based monomer having an acrylate-based monomer as a main component and a photopolymerization initiator such as benzoin methyl ether is contained. Control the intensity of UV light (UV light with wavelength of 300 to 400 nm is 0.1 to 7
Irradiation with a light intensity of mW / cm ² ) and higher molecular weight are used for improvement. However, this improved method has a drawback that the production speed cannot be increased because the light intensity is kept low.

As a method for improving this, Japanese Patent Application No. 3-129326 discloses a method of adding vinyl acetate to an acrylic monomer composition. This method uses Alfrey
Since the Q value indicating the monomer reactivity ratio between the monomer and the price (for the Q value, see “Copolymerization” published by Baifukan on June 20, 1975, edited by the Society of Polymer Science, P.12, etc.), the reactivity of the monomer itself is low. Although vinyl acetate remains low until the latter stage of the reaction, the radicals produced by the reaction show high reactivity, so the reaction can be completed more quickly, and in addition, the lamp intensity is increased and the amount of initiator is increased to increase the productivity. Even if the high-speed reaction condition is set, a low-molecular weight polymer is not produced, and therefore the production speed can be increased.

[0008]

However, although this method can increase the production speed, the adhesive performance of the obtained adhesive tape was comparable to that without the addition of vinyl acetate.

An object of the present invention is to provide a photopolymerizable composition for producing a viscoelastic product containing a photopolymerization initiator and substantially not containing a solvent, which has both productivity (production speed) and adhesive performance. It is an object of the present invention to provide a novel photopolymerizable composition capable of producing an acrylic viscoelastic product maintained at a high level. Further, another object is to provide a polymerization method having lower odor and good physical properties as an adhesive.

Another object of the present invention is to provide a photopolymerizable composition and a polymer obtained from the polymerization method, that is, an acrylic viscoelastic product.

As a result of intensive studies, the present inventors have found that instead of blending vinyl acetate with a vinyl-based monomer containing an alkyl (meth) acrylate as a main component, the homopolymer has a glass transition temperature of 35 ° C. Above, and Alfrey
It has been found that the above object can be achieved by blending a vinyl carboxylate monomer having a Q value of 0.45 or less, which indicates the monomer reactivity ratio of the product and Price, and has completed the present invention.

Further, the above photopolymerizable composition is irradiated with light to obtain at least 5 parts of the acrylic vinyl monomer component.
After polymerizing 0% by weight, subsequently, by further irradiating with light of which the intensity is higher than this light, the residual amount of vinyl carboxylate monomer is small and the polymerization rate is high. It was also found that a good polymer can be obtained, and the present invention has been completed based on this finding.

[0013]

That is, according to the present invention,
(a) A vinyl-based monomer containing (meth) acrylic acid alkyl ester as a main component, and (b) a Q value showing the monomer reactivity ratio of Alfrey and Price when the glass transition temperature of the homopolymer is 35 ° C or higher. Provided are a photopolymerizable composition comprising a vinyl carboxylate monomer having a ratio of 0.45 or less, and (c) a photopolymerization initiator, and a polymer obtained by irradiating the photopolymerizable composition with a photopolymerizable composition. ..

Further, according to the present invention, the photopolymerizable composition is irradiated with light to polymerize at least 50% by weight or more of the vinyl-based monomer (a) component, and then, the intensity is higher than this light. By further illuminating the
There is provided a polymerization method characterized by substantially completing the polymerization reaction of the above composition, and a polymer obtained by this polymerization method.

Each component constituting the photopolymerizable composition according to the present invention and the photopolymerization method of the composition will be described below.

(1) Each component constituting the photopolymerizable composition vinyl-based monomer (a) The vinyl-based monomer component used in the present invention is a (meth) acrylic acid having an alkyl group having 1 to 14 carbon atoms. 60 to 100% by weight of at least one (meth) acrylate monomer selected from alkyl esters, and 0 to 40% by weight of another vinyl-based monomer copolymerizable with the (meth) acrylate monomer. is there.

(Meth) acrylate monomer The (meth) acrylate monomer is used in the production of known photopolymerized acrylic viscoelastic products.

As the (meth) acrylate monomer,
Acrylic acid alkyl ester or methacrylic acid alkyl ester in which the alkyl group has 1 to 14 carbon atoms, preferably 4 to 12 carbon atoms is used. Specific examples of these acrylate-based monomers include n-butyl (meth) acrylate,
Examples thereof include 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, and isononyl (meth) acrylate.

These monomers may be used alone or in combination with each other.
Used in combination of two or more species. From the standpoint of balance between tackiness and cohesiveness, usually, a homopolymer has a glass transition temperature of -50 ° C or less as an acrylic acid alkyl ester as a main component, and a (meth) acrylic acid ester of a lower alkyl group or the following vinyl is used as a comonomer. It is preferable to use a system monomer.

Other vinyl monomers copolymerizable with other vinyl monomers (meth) acrylate monomers include, for example, acrylic acid, methacrylic acid, acrylamide, acrylonitrile, methacrylonitrile, N-substituted acrylamide, and hydroxyethyl. Examples thereof include acrylate, carboxyethyl acrylate, N-vinylpyrrolidone, maleic acid, itaconic acid, N-methylol acrylamide, hydroxyethyl methacrylate and the like.

Among these vinyl monomers, acrylic acid, carboxyethyl acrylate and N-vinylpyrrolidone are particularly preferable. These monomers have the property of having a polymerization reaction accelerating effect by themselves and a small effect of decreasing the molecular weight during the accelerating reaction.

Further, a vinyl-based monomer forming a polymer having a low glass transition temperature, for example, a vinyl-based monomer such as tetrahydrofurfuryl acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, fluorine acrylate or silicon acrylate can be used.

These vinyl-based monomers may be used alone or in combination of two or more.

These (meth) acrylate monomers and vinyl monomers are (meth) acrylate monomers 60
-100% by weight and 0-40% by weight of vinyl monomer. When the content of the vinyl-based monomer is more than 40% by weight, the adhesive properties of the pressure-sensitive adhesive tape as an acrylic pressure-sensitive adhesive are deteriorated, which is not preferable. The preferred mixing ratio is 75 to 98% by weight of the (meth) acrylate monomer and 2 to 25% by weight of the vinyl monomer.

The homopolymer has a glass transition temperature (Tg) of 3
The monomer reactivity ratio of Alfrey and Price is 5 ℃ or more.
Vinyl carboxylate monomer having a Q value of 0.45 or less
-(B) The Q value, which indicates the monomer reactivity ratio between Alfrey and Price, is a certain free radical (radical) (for example, benzoyl radical), as can be seen from “Copolymerization” (P.12, edited by the Polymer Society of Japan). Etc.) with a monomer, and when a monomer having a high Q value is compared with a monomer having a low Q value, a monomer having a low Q value has a smaller reactivity. However, once the monomer reacts with the free radical and becomes a radical,
In general, a radical generated from a monomer having a low Q value has higher reactivity with another specific monomer (for example, a styrene monomer) than a radical generated from a monomer having a high Q value.

That is, it can be said that the Q value indicates the degree of resonance stabilization of radical electrons in the monomer molecule. (A monomer having high resonance stability is likely to become a radical, but it is difficult to react with other monomers.) As an example of the Q value, acrylic acid esters are about 0.40 to 0.45, Acrylic acid is about 1.27 and carboxylic acid vinyl ester monomers are about 0.01-0.10.

Therefore, as a specific example of the vinyl carboxylate monomer whose homopolymer used in the present invention has a glass transition temperature of 35 ° C. or higher and a Q value of 0.45 or lower, vinyl benzoate (Tg: 75 ° C.) , Q value: 0.061), vinyl pivalate (Tg: 86 ° C., Q value: about 0.05),
Examples thereof include vinyl versatate (manufactured by Shell Chemical Co., Ltd .; trade name “Veoba 9”, Tg: 60 ° C., Q value: about 0.05). Of these, vinyl benzoate and vinyl pivalate are preferable. In particular, vinyl pivalate, which is an aliphatic carboxylic acid, has a higher rate of residual monomer reduction in the latter stage of the reaction, compared to vinyl benzoate, which is an aromatic carboxylic acid. Therefore, in terms of production rate and product quality (odor), More desirable.

In the present invention, the vinyl carboxylate monomer (b) is a vinyl monomer (a) comprising the above-mentioned (meth) acrylate monomer and another vinyl monomer copolymerizable with the (meth) acrylate monomer. Can be used in an amount of 0.1 to 40 parts by weight with respect to 100 parts by weight as a total. Preferably 1 to 10 parts by weight can be used.

Photopolymerization initiator (c) As the monofunctional photopolymerization initiator, for example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone [Darocur 2959: manufactured by Merck], α
Acetophenone initiators such as -hydroxy-α, α'-dimethylacetophenone [Darocur 1173: manufactured by Merck], methoxyacetophenone, and 2,2-dimethoxy-2-phenylacetophenone; benzoin ethers such as benzoin ethyl ether and benzoin isopropyl ether. Examples thereof include a system initiator; a ketal system initiator such as benzyl dimethyl ketal; and a halogenated ketone, an acylphosphinoxide, an acylphosphonate and the like.

The photopolymerization initiator is the monomer component (a) 1
0.1 to 5.0 parts by weight are blended with respect to 00 parts by weight. If the blending amount is less than 0.1 part by weight, the photopolymerization initiator is consumed by the light energy at the initial stage of polymerization, so that unreacted monomers are likely to remain and only a monomer odor remains in the obtained polymer. But the cohesive strength is reduced. On the other hand, if it exceeds 5.0 parts by weight, the polymerization reaction rate increases, but the residual odor accompanying the decomposition of the photopolymerization initiator becomes severe,
Further, the obtained polymer has a large variation in molecular weight, and the adhesive performance is also deteriorated. A preferred blending amount is 0.3 to 2.0
Parts by weight.

Optional ingredients that may be added to the photopolymerizable composition of the present invention.
In partial-polymerizable crosslinking agent photopolymerizable composition of the present invention, the content in order to increase the cohesive force of a heat-resistant i.e. high temperatures, together with the photopolymerization initiator, the polyfunctional vinyl compound as the polymerizable cross-linking agent Preferably.

Examples of such crosslinking agents 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,
Examples thereof include polyester acrylate and urethane acrylate.

The cross-linking agent is generally added in an amount of 5 parts by weight or less based on 100 parts by weight of the monomer component (a). The incorporation of the cross-linking agent causes cross-linking between polymer molecules in the photopolymerization reaction, thereby improving the heat resistance of the polymer. When the polymer is a pressure-sensitive adhesive tape, the cohesive force at high temperature is increased and the holding power is improved.

Tackifying Resin (Tackifier) The photopolymerizable composition according to the present invention is further referred to as a tackifier in the above monomer composition system in order to impart a high level of tack to viscoelastic products. A tackifying resin can also be included.

Examples of tackifiers used in the present invention include rosin resins, modified rosin resins (hydrogenated rosin resins, disproportionated rosin resins, polymerized rosin resins, etc.), terpene resins, terpene phenol resins, and aromatic resins. Modified terpene resins, C ₅ and C ₉ petroleum resins, coumarone resins and the like.

Other Additives The photopolymerizable composition according to the present invention may be mixed with commonly used additives such as a thickener, a thixotropic agent, a filler and a filler.

Acrylic rubber, epichlorohydrin rubber, isoprene rubber, butyl rubber and the like are used as the thickener.

As the thixotropic agent, colloidal silica, polyvinylpyrrolidone, etc. are used.

As the extender, calcium carbonate, titanium oxide, clay, etc. are used.

Examples of the filler include inorganic hollow bodies such as glass balun, alumina balun, ceramic baln; organic spherical bodies such as nylon beads, acrylic beads, and silicon beads; organic hollow bodies such as vinylidene chloride, acrylic balun; polyester, rayon. A single fiber such as nylon is used.

(2) Photopolymerization Method of Photopolymerizable Composition Preparation Work and Light Source Before Irradiation In order to obtain a polymer using the photopolymerizable composition of the present invention, dissolved oxygen in the composition is usually used. For removal, purging with an inert gas such as nitrogen gas or adding a compound having an oxygen removing effect such as phenyldiisodecyl phosphite, triisodecyl phosphite and stannous octoate. By adding such a compound, sufficient polymerization (curing) can be realized even if the oxygen concentration in the atmosphere is high to some extent.

As a polymer, for example, in the case of producing an adhesive tape, the photopolymerizable composition is applied or injected onto a release paper, a release mold, or the like, or a plastic film, paper, cellophane, cloth, nonwoven fabric. , Coating or impregnating a base material such as metal foil. When the base material is not impregnated, an adhesive tape without the base material is obtained. When a sealing material is produced as a polymer, the photopolymerizable composition is injected into a strippable elongated mold or the like.

Coating the photopolymerizable composition on a mold or substrate,
When impregnating or pouring, so that the work can be done smoothly,
It is preferable to thicken with a thickener. 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, an apparatus 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 light such as ultraviolet light or visible light is irradiated through quartz glass, Pyrex glass, or borate glass. Further, even in an inert gas atmosphere, by covering the surface of the photopolymerizable composition applied, impregnated or injected into a mold or substrate with a polyester film having releasability, air (oxygen ), And may be irradiated with light while preventing contact with the same. In this case, it is preferable to add the compound having the oxygen removing effect.

Ultraviolet rays are usually used for light irradiation. As the ultraviolet lamp, one having an emission spectrum distribution in a light wavelength of 300 to 400 nm is used, and examples thereof include a chemical lamp, a black light lamp (trade name of Toshiba Denshi Co., Ltd.), a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, 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 and the latter five lamps are
Used to obtain relatively high light intensity.

Irradiation method (polymerization method) The light intensity can be adjusted by adjusting the distance to the object to be irradiated and the voltage.
Generally, the irradiation time is 1 to 0.5 to 100 mW / cm ^2.
It is set to 0 seconds to 5 minutes.

By irradiation with light such as ultraviolet rays, a vinyl-based monomer component containing (meth) acrylic acid alkyl ester as a main component is polymerized to obtain a polymer. With the above irradiation time (polymerization reaction time), the residual monomer content is reduced to about 0.5% by weight or less, and the polymerization reaction can be substantially completed.

The light irradiation may be carried out at a constant light intensity, but the physical properties of the obtained polymer may be adjusted more precisely by changing the light intensity in two or more steps. it can.

The invention of claim 3 is a polymerization method characterized in that the light intensity is changed in two steps, and specifically, the initial light intensity is generally about 0.5 to 100 mW / cm ² ,
Polymerization is performed by irradiation for about 10 seconds to 5 minutes depending on the light intensity until the residual rate of the vinyl-based monomer component (a) becomes 50% by weight or less, preferably 30% by weight or less.

Subsequently, irradiation with light having a higher intensity than the initial intensity, preferably 1.1 times or more, more preferably 2 times or more, is continued for about 10 seconds to 5 minutes, and the remaining monomer components and About 0.5 of carboxylic acid monomer component
The content is made to be less than or equal to wt% to substantially complete the polymerization reaction.

At this time, if the light intensity is increased while the residual rate of the vinyl-based monomer component (a) exceeds 50%, a large amount of low molecular weight substances having a low glass transition temperature will be produced, resulting in deterioration of physical properties. Will be invited.

[0053]

In the present invention, instead of blending vinyl acetate with vinyl monomer (a) containing (meth) acrylic acid alkyl ester as a main component, the homopolymer has a glass transition temperature of 25 ° C. or higher, and By using a photopolymerizable composition containing a vinyl carboxylate monomer (b) having a Q value of 0.45 or less indicating the monomer reactivity ratio of Alfrey and Price, the residual amount of vinyl carboxylate monomer is small and It has become possible to improve the adhesive property while maintaining a high speed.

Further, the acrylic vinyl monomer component
By polymerizing at least 50% by weight or more of (a) and then irradiating with more intense light, the residual amount of vinyl carboxylate monomer is further reduced, and the odor is maintained while maintaining the adhesive physical properties of the adhesive tape. It has become possible to provide an improved polymerization method.

First, the reason why the polymerization rate becomes faster is that the monomer having a low Q value has low reactivity as described above and remains in the monomer until the latter stage of the reaction, but the radical produced by the reaction has high reactivity. It is believed that this is because the reaction can be completed more quickly because it has.

Further, the residual amount of the aliphatic vinyl carboxylate monomer is smaller than that of the aromatic vinyl carboxylate monomer, because the latter is stabilized by the formation of Complexed radicals and the polymerization rate becomes slow. On the other hand, it is considered that the former is not affected by such polymerization inhibition. (About Complexed V.Sta
nnett et al., Makromol. Chem. 73 , 177 (1974)).

Furthermore, the reason why the residual amount of vinyl carboxylate monomer decreases by increasing the light intensity in the latter stage of the polymerization is that the vinyl carboxylate monomer remaining at the end of the initial light irradiation is faster due to the irradiation of stronger light. It is thought to be consumed.

The reason why the adhesive property is improved is considered as follows. It is known that in radical bulk polymerization, the molecular weight of the polymer produced in the latter stage of the polymerization is generally low. An adhesive containing a large amount of a low molecular weight polymer has poor adhesive physical properties, particularly cohesive force. Therefore, it is considered that the conventional pressure-sensitive adhesive has low adhesive performance. However, when the glass transition temperature of this low molecular weight polymer is high, it is considered that the decrease in cohesive force is small (because those having a high glass transition temperature generally have high cohesive force). Therefore, the vinyl carboxylate monomer having a low Q value (0.45 or less) of the present invention remains until the latter stage of the polymerization, and its homopolymer has a high glass transition temperature (35 ° C. or higher), so that the obtained polymer has a low molecular weight. However, the decrease in cohesive force is small,
Therefore, it is considered that the adhesive property is improved. (This is considered to be the same action as changing the tackifier added to the acrylic pressure-sensitive adhesive from one having a low glass transition temperature to one having a high glass transition temperature.)

[0059]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples showing examples of the present invention, but the present invention is not limited thereto.

<Method for measuring physical properties of pressure-sensitive adhesive tape> With respect to the double-sided pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples, the weight average molecular weight of the pressure-sensitive adhesive was measured by the following measuring method (measured only in the case where no polymerizable crosslinking agent was added). The amount of residual monomer, the reaction completion time, the gel fraction, the degree of swelling, the adhesive strength, and the holding power were measured.

(1) Weight average molecular weight The sample was dissolved in tetrahydrofuran so as to have a concentration of 1.0% by weight and left for 24 hours. The sample solution obtained by removing the insoluble matter from this was subjected to gel permeation chromatography (GPC) with reference to standard polystyrene, using a refractive index detector for general polymers, and a substituent having visible ultraviolet absorption. For polymers with ## STR1 ## were also measured using a visible-ultraviolet detector. The GPC system used was a liquid sending device LC-9A, a refractive index detector RID-6A, a visible-ultraviolet detector SPD-6A.
V, column oven CTO-6A, data analyzer C-
R4A (all manufactured by Shimadzu Corporation). GPC column has 3 GPC-805 (exclusion limit 4 million), G
PC-804 (exclusion limit 400,000), GPC-801
(Exclusion limit 1500) One piece (all manufactured by Shimadzu Corporation) was connected in this order and used. The measurement conditions were as follows: sample injection amount 25 μl, eluent tetrahydrofuran, liquid transfer amount 1.
0 ml / min, column temperature 45 ° C.

(2) Remaining monomer amount / reaction completion time 100 mg of the adhesive sample taken at regular intervals was dissolved in 5 ml of methyl acetate, and 2 ml of this solution and 2 ml of an internal standard solution prepared by dissolving 2-ethylhexyl methacrylate in methyl acetate. And were mixed to prepare a sample for measuring the amount of residual monomer (2-ethylhexyl acrylate, 2EHA). The measurement is
It was carried out using a gas chromatograph (GC-6A, manufactured by Shimadzu Corporation) having a separation column obtained by acid-treating chromosorb W carrying polyethylene glycol (manufactured by Gascro Industrial Co., Ltd., trade name "20M") and a hydrogen flame ionization detector. .. Next, the vertical axis represents the amount of residual monomer (2EHA) and the horizontal axis represents the reaction time.
The time when the amount of A became 0.3% by weight or less was defined as the reaction completion time. The amount of residual vinyl carboxylate monomer was measured by preparing an internal standard solution of the monomer in the same manner as above and by the same method as above.

(3) Gel Fraction / Swelling Rate 100 mg of the adhesive sample was dissolved in tetrahydrofuran to prepare 24
What was left for a time was filtered with a 200 mesh stainless steel filter. It was determined by measuring the weight of the swollen gel collected by filtration and the weight of the dried gel obtained by drying the swollen gel at 100 ° C. for 2 hours.

(4) Adhesive strength A 25 μm-thick polyester film is attached to one side of a double-sided adhesive tape to form an adhesive tape having a width of 25 mm and a length of 300 mm, and this is applied to a stainless plate polished with a No. 280 paper file. , The length from one end of the tape is 100-120mm
The part of 2 was reciprocated once with a 2 kg roller, and was attached.
Next, at 23 ° C. and 65% RH, the other end of this tape was placed at 18 mm at a speed of 300 mm / min with an Instron tensile tester.
Peeling was carried out in the direction of 0 degree angle, and the peeling resistance at that time was measured to obtain the adhesive strength (g / 25 mm width).

(5) Holding power An aluminum foil having a thickness of 100 μm was attached to one surface of the double-sided adhesive tape to form an adhesive tape having a width of 25 mm, which was attached to a stainless steel plate polished with a No. 280 paper file and one end of the tape was applied. The part was attached by reciprocating once with a 2 kg roller so that the adhesive area had a width of 25 mm and a length of 25 mm. next,
A 1 kg weight was fixed to the other end of this tape, which was hung in an atmosphere of 80 ° C., and the time until the weight dropped together with the tape was measured and used as the holding force (time).

The holding power is usually measured at 40 ° C., but the measurement time was shortened by performing the measurement under a severe condition of 80 ° C. The measurement was conducted for up to 40 hours.

[0067]

Example 1 2-Ethylhexyl acrylate (2EH
A) 100 parts by weight of a monomer component consisting of 90% by weight, N-vinylpyrrolidone (VP) 8% by weight and acrylic acid (AA) 2% by weight, vinyl benzoate (VB) 7 parts by weight and a photopolymerization initiator 1.34 parts by weight of Darocur 2959 (trade name, manufactured by Merck) and 0.05 parts by weight of hexanediol diacrylate (HDDA) as a polymerizable cross-linking agent are added and stirred by a stirrer to uniformly mix, and photopolymerized. A sex composition was obtained.

The photopolymerizable composition thus obtained was purged with nitrogen gas to remove dissolved oxygen, and then impregnated into a nylon nonwoven fabric on a transparent polyester film treated with a release agent, and the surface thereof was transparent as described above. Covered with polyester film. Then, using an ultra-high pressure mercury lamp as a radiation source, the light intensity of the irradiated surface was 28 mW / cm ² (365 nm).
Was irradiated with ultraviolet rays for 2.0 minutes with a light intensity measuring instrument UVR-1 (manufactured by Tokyo Optical Machinery Co., Ltd.) having the maximum sensitivity to prepare a double-sided adhesive tape having a film thickness of 220 μm.

Table 1 shows the measurement results of weight average molecular weight, reaction completion time, gel fraction, swelling degree, adhesive strength and holding power.
Shown in. The weight average molecular weight is measured with respect to a polymer produced under the same conditions as the above-mentioned formulation except that HDDA is not added in order to avoid gel formation (Example 2 and Comparative Example 1 below). The same applies to case 2).

The physical properties of the obtained tape were good in both adhesive strength and holding power, and sufficient performance as a double-sided adhesive tape was exhibited.

Example 2 Vinyl benzoate was replaced with vinyl pivalate (VP).
The same operation as in Example 1 was performed except that v) was replaced,
A double-sided adhesive tape was manufactured. The measurement results are shown in Table 1. The physical properties of the obtained tape were as good as those of Example 1,
A double-sided pressure-sensitive adhesive tape having sufficient performance and having a small amount of residual vinyl carboxylate monomer and improved odor was obtained.

Comparative Example 1 A double-sided pressure-sensitive adhesive tape was manufactured in the same manner as in Example 1 except that the vinyl carboxylate monomer was not added. The measurement results are shown in Table 1.

At this time, the reaction completion time was 1.4 minutes, which was longer than that in Examples. The weight average molecular weight was the same as that of the example. Regarding the physical properties of the obtained tape, the adhesive strength was equivalent to that of the tape of the example, but the holding power was 10
The time was low and the performance was insufficient as a double-sided adhesive tape.

From the feel of the finger, the pressure-sensitive adhesive obtained here was softer as a viscoelastic body than the pressure-sensitive adhesives of the examples, and the cohesive force was insufficient and a polymer unsuitable for the pressure-sensitive adhesive was produced. Is shown.

Comparative Example 2 A double-sided pressure-sensitive adhesive tape was manufactured in the same manner as in Example 1 except that 7 parts by weight of vinyl acetate (VAc) was blended as the vinyl carboxylate monomer. The measurement results are shown in Table 1.

The reaction completion time at this time was 0.9 minutes, which was equivalent to that of Example 1 and faster than that of Comparative Example 1. The gel fraction, swelling degree, and weight average molecular weight were the same as in Example 1. Regarding the physical properties of the obtained tape, the adhesive strength was equivalent to that of the tape of the example, but the holding power was as low as 15 hours, and insufficient performance was obtained as a double-sided adhesive tape.

From the feel of the fingers, the adhesive obtained here was softer as a viscoelastic body than the adhesives of the examples, and the cohesive force was insufficient and a polymer unsuitable as an adhesive was produced. Is shown.

[0077]

[Table 1]

[0078]

Example 3 A photopolymerizable composition prepared in exactly the same manner as in Example 1 was irradiated with ultraviolet rays at a light intensity of 28 mW / cm ² for 0.5 minutes (the amount of residual 2EHA at this point was 20% by weight), and then, Irradiation with 56 mW / cm ² for 1.5 minutes and photopolymerization for a total of 2.0 minutes to produce a double-sided adhesive tape having a film thickness of 220 μm. Table 2 shows the measurement results of each physical property.

The weight average molecular weight is 47 in the refractive index detector.
10,000 with a visible-ultraviolet detector. This means that the VB component is contained in a large amount in the low molecular weight. In addition, the physical properties of the obtained tape were good in both adhesive strength and holding power, sufficient performance as a double-sided adhesive tape was exhibited, and odor was less than that of Example 1.

[0080]

Example 4 Vinyl pivalate (VP) was added to vinyl benzoate.
Except substituting v), the same operation as in Example 3 was performed,
A double-sided adhesive tape was manufactured. However, the amount of residual 2EHA after 0.5 minutes was 28% by weight. The measurement results are shown in Table 2.

The physical properties of the obtained tape were as good as those of Example 3, and sufficient performance as a double-sided pressure-sensitive adhesive tape was exhibited, and a tape with extremely little odor was obtained.

[0082]

[Comparative Example 3] Except that vinyl benzoate was not added,
The same operation as in Example 3 was carried out to produce a double-sided pressure-sensitive adhesive tape. However, the amount of residual 2EHA at the time point after 0.5 minutes was 26% by weight. The measurement results are shown in Table 2.

At this time, the reaction completion time was 1.35 minutes, which was longer than that in Examples. Further, the gel fraction, the degree of swelling, and the weight average molecular weight were the same as those of the examples, and the physical properties of the obtained tapes were the same as those of the tapes of the examples, but the holding power was as low as 3 hours. However, the performance was insufficient as a double-sided adhesive tape.

From the feel of the finger, the adhesive obtained here was also softer as a viscoelastic body than the adhesives of the examples, and the cohesive force was insufficient, which made the polymer unsuitable as an adhesive. Is generated.

[Table 2]

[0085]

According to the photopolymerizable composition of the present invention, a vinyl-based monomer (a) containing a (meth) acrylic acid alkyl ester as a main component has a homopolymer whose glass transition temperature is 35 ° C. or higher. In addition, since the vinyl carboxylate monomer (b) having a Q value showing the monomer reactivity ratio of Alfrey and Price of 0.45 or less is blended, the polymerization reaction rate remains high,
The adhesive property can also be improved. In particular, in the case of an aliphatic vinyl carboxylate monomer, the residual amount of the monomer can be reduced, so that the odor of the product is improved.

Further, according to the method for polymerizing the photopolymerizable composition of the present invention, the polymerization reaction rate is large and the adhesive property is maintained, and further, the residual amount of vinyl carboxylate monomer can be further reduced, and the product is produced. The effect of improving the odor due to the monomer is remarkable.

The photopolymerizable composition or polymer obtained by the present invention includes, for example, adhesive tapes, heat-sensitive adhesive sheets, sealing materials for construction and automobiles, anti-vibration materials,
It is useful for various applications such as intermediate films.

Claims (5)

[Claims] 1. A vinyl-based monomer comprising (a) an alkyl (meth) acrylate as a main component, and (b) a homopolymer thereof having a glass transition temperature of 35 ° C. or higher and monomer reactivity between Alfrey and Price. A photopolymerizable composition comprising a vinyl carboxylate monomer having a Q value showing a ratio of 0.45 or less and (c) a photopolymerization initiator. 2. (a) 60 to 100% by weight of at least one (meth) acrylate monomer selected from the group consisting of (meth) acrylic acid alkyl esters in which the alkyl group has 1 to 14 carbon atoms, and Other vinylic monomers 0 to 40 copolymerizable with (meth) acrylate monomer
100 parts by weight of a vinyl-based monomer consisting of 10% by weight, and (b) vinyl benzoate or vinyl pivalate 0.1 to 4
A photopolymerizable composition comprising 0 parts by weight and (c) 0.1 to 5.0 parts by weight of a photopolymerization initiator. 3. A polymer obtained by irradiating the photopolymerizable composition according to claim 1 or 2 with light. 4. The photopolymerizable composition according to claim 1 or 2 is irradiated with light to polymerize at least 50% by weight or more of the vinyl-based monomer (a) component, and then the intensity is higher than this light. A method of polymerization characterized in that the polymerization reaction of the above-mentioned composition is substantially completed by further irradiating with light having an increased temperature. 5. A polymer obtained by the polymerization method according to claim 4.