JPH0126632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of manufacturing an adhesive tape without using a solvent.

(Prior art) Conventionally, adhesive tapes, whether single-sided or double-sided, have been made by coating a base material with a polymer dissolved in a solvent and forming an adhesive layer after the solvent has evaporated. Even if an emulsion is used, the water must be volatilized.

It goes without saying that there is a tendency to avoid the use of solvents due to environmental hygiene, fire danger, and cost considerations, but in reality, there is no other option. The reality is that it continues out of necessity.

Although the method using emulsion does not pose a fire risk, the energy and time required to volatilize the water are major factors preventing the spread of this method.

In addition, emulsions may have physical properties that are not as good as those of solvent-based emulsions, depending on the required performance.

(Problems to be Solved by the Invention) The present inventors have made repeated studies to solve the problems in the production of adhesive tapes, but until now they have used known monomers having (meth)acryloyl groups or It has been found that although a soft coating film can be obtained by curing oligomers (hereinafter abbreviated as oligoacrylate) by light or electron beam irradiation, it is difficult to obtain a practical adhesive.

Furthermore, when monomers are mixed with these oligoacrylates in amounts sufficient to produce tackiness, curing is significantly delayed, and even in the absence of air, very practical polymerization rates may not be obtained. found. In the end, it is difficult to use a molecular weight similar to that of oligoacrylates, that is, about 500 to 2,000.

(Means for solving the problem) Thus, the present inventors used a high molecular weight rubbery polymer having an acryloyl group and/or a methacryloyl group (hereinafter abbreviated as (meth)acryloyl group) in the side chain via a urethane bond. We found that the purpose could be achieved by
We learned that the range of products could be further expanded by using a tackifier in combination, and were able to complete the present invention.

That is, the present invention provides a rubbery polymer having a (meth)acryloyl group in the side chain via a urethane bond, monomers that dissolve the rubbery polymer,
A method for producing an adhesive tape, which comprises coating a base material with a mixture of oligomers that are compatible with the rubbery polymer and useful for tackification, and irradiating the mixture with active energy rays in the absence of air. be.

(Function) In the present invention, monomers constituting a rubbery polymer having a (meth)acryloyl group in a side chain via a urethane bond as one component are monomers whose glass transition temperature is 30°C or lower. The glass transition temperature of the polymer is determined as necessary.
Monomers with a temperature higher than 30℃, monomers for introducing the necessary hydroxyl groups into the polymer, and unsaturated isocyanate for reacting with the hydroxyl groups of the polymer to introduce (meth)acryloyl groups into the side chains via urethane bonds. It's Naat.

Rubbery polymers having (meth)acryloyl groups in their side chains via urethane bonds are produced by first copolymerizing the above monomers to produce a polymer having hydroxyl groups in their side chains, and then adding unsaturation to the hydroxyl groups of this polymer. It is produced by reacting isocyanate groups in isocyanates.

The monomers constituting the polymer having a hydroxyl group in the side chain vary depending on the required tackiness and adhesion, but monomers whose glass transition temperature is 30° C. or lower are generally suitable. Examples of such monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and n-methacrylate.
Examples include butyl, isobutyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate, ethylene, butadiene, vinyl acetate, and the like.

It is practical to copolymerize the above-mentioned monomers with monomers whose glass transition temperature is higher than 30°C, if necessary, from the viewpoint of adjusting adhesiveness and developing strength. It is not preferable to use monomers with a glass transition temperature higher than 30° C. alone because the adhesive properties of the adhesive decrease. Examples of monomers whose polymer glass transition temperature is higher than 30°C include styrene, vinyltoluene, acrylonitrile, methyl methacrylate,
Examples include ethyl methacrylate and cyclohexyl methacrylate.

Furthermore, examples of monomers for introducing the necessary hydroxyl groups into the polymer include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and 2-hydroxyethyl methacrylate.

By reacting with the hydroxyl group of the polymer having hydroxyl groups obtained by copolymerizing the above monomers, (meth)
Examples of the unsaturated isocyanate for introducing an acryloyl group include unsaturated isocyanates having an isocyanate group and a (meth)acryloyl group in the molecule represented by the following formula.

The unsaturated isocyanate (1) above is usually obtained by adding 1 mol or more of unsaturated alcohol to 1 mol of diisocyanate and reacting.

Diisocyanates include currently commercially available types, such as 2,4-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate.
- tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and the like.

Examples of the unsaturated alcohol include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

When a polymer having a hydroxyl group in the side chain is reacted with an unsaturated isocyanate, a (meth)acryloyl group is added to the polymer side chain via a urethane bond, resulting in the following type of rubbery polymer.

Rubber-like polymers that have (meth)acryloyl groups in their side chains via urethane bonds are easier to synthesize and have faster photocuring speeds than polymers that have (meth)acryloyl groups in their side chains via ester bonds. It is ideal for producing the adhesive tape of the present invention because it can be quickly applied, and when made into an adhesive tape, it has excellent tackiness, adhesive strength, and holding power.

The above-mentioned rubbery polymer having a (meth)acryloyl group in its side chain preferably has a molecular weight of 10,000 or more. If the molecular weight is less than 10,000, the strength as an adhesive is insufficient.

The degree of unsaturation of a rubbery polymer having a (meth)acryloyl group in the side chain naturally varies depending on the required physical properties, but when it is used for adhesive tapes, the degree of unsaturation of the total monomers constituting the rubbery polymer is 100%. (%), the unsaturated portion is suitably 0.1 mole (%) or more and 30 mole (%) or less, and usually 2 mole (%) or more and 20 mole (%) or less is used.

If the degree of unsaturation of a rubbery polymer with (meth)acryloyl groups in the side chain is less than 0.1 mole (%), curing will be slow, and depending on the components of the polymer and monomer, phase separation may occur and the adhesiveness will be impaired. On the other hand, if the degree of unsaturation of the polymer is more than 30 moles (%), the adhesive tape tends to be hard.

In the present invention, in order to further improve the tackiness and adhesion of the rubbery polymer having (meth)acryloyl groups in its side chains, oligomers (tackifiers) that are compatible with the rubbery polymer are used. It is necessary to use them together. Oligomers useful for tackification used in the present invention include (a) types that do not have reactivity and simply dissolve in rubbery polymers having (meth)acryloyl groups in their side chains to improve tackiness; ) Adhesive tapes have reactivity as well as tackifying properties, and are roughly divided into types that require some kind of reaction after being produced and are cured to improve physical properties such as increasing adhesive strength and imparting heat resistance. be done.

A typical example of non-reactive oligomers useful for tackification belonging to (a) is saturated polyester.

Saturated polyester is synthesized by esterification of polyhydric alcohol and polybasic acid or its acid anhydride, and can be produced in a variety of forms from liquid to syrup and solid at room temperature. It can be selected depending on the purpose.

(b) Reactive oligomers have (meta) side chains.
It is effective for adhesion of rubbery polymers having acryloyl groups, and at the same time, it can be copolymerized to form a polymer component during polymerization of rubbery polymers, or it can remain adhesive without participating in the polymerization after polymerization of rubbery polymers. Although it acts as an imparting agent, it is useful for improving heat resistance and increasing adhesive strength by curing it later if necessary.

Typical examples of oligomers useful for tackification include: (a) containing α-β unsaturated polybasic acids, obtained by esterification with polyhydric alcohols, with or without modification with any saturated acid; unsaturated alkyds, (b) epoxy resins in liquid, syrup or solid form, (c) hydroxyl polyesters, polyethers,
Examples include polyisocyanate in which the terminal hydroxyl group of is converted to an isocyanate group.

Which of (a) and (b) to use is determined by the performance required of the adhesive tape.

The amount of oligomers to be used is 10 parts by weight or more per 100 parts by weight of the rubbery polymer having a (meth)acryloyl group in the side chain and monomers.
The appropriate amount is less than parts by weight, and the most desirable amount is
The amount is 30 parts by weight or more and 100 parts by weight or less.

When the amount of oligomers used is less than 10 parts by weight, the tackifying effect is weak, and when it is more than 200 parts by weight, adhesiveness tends to decrease.

Next, as the monomers to be mixed into the rubbery polymer having a (meth)acryloyl group in the side chain, monomers that are liquid at room temperature and whose glass transition temperature is 30°C or lower are preferably used, but if necessary, In this case, monomers whose polymer glass transition temperature is higher than 30°C may be used in combination.

The mixing ratio of the rubbery polymer having a (meth)acryloyl group in the side chain and the monomers varies depending on the viscosity required for the application, but is usually between several poise and several hundred poise at the coating temperature. Since existing coating equipment such as flow coaters and roll coaters can be used, the concentration of the rubbery polymer having a (meth)acryloyl group in the side chain is approximately 5 to 60% by weight. Preferably 10~
It is within the range of 55% by weight.

When photocuring a monomer solution of a rubbery polymer having a (meth)acryloyl group in a side chain and an oligomer, a radical generator called a photosensitizer is usually used.

Examples of these include, for example, benzoin ethers,
Examples include substituted benzophenones, combination systems with tertiary amines, acetophenone derivatives, dialkylbenzyl ketals, dibenzyl, etc. These are usually 0.5 to 5 parts by weight (100 parts by weight of a mixture of rubbery polymers, monomers, and oligomers). used for) It goes without saying that colorants, fillers, etc. can be used in combination with the mixture according to the present invention, if necessary.

The condition of the absence of air is sometimes referred to as inert gas replacement, but the cost for this cannot be ignored, and in the present invention, release paper or film treated with silicone resin is used instead. , the mixture is coated on paper, nonwoven fabric, plastic film, release paper, or release film that serves as the base material of the tape, and both are adhered and degassed, and active energy rays are applied to the base material of the tape in a state substantially unaffected by air. It is useful to irradiate When energy beams are irradiated in the presence of air, the mixture does not polymerize, making it difficult to obtain the desired adhesive tape.

If the product does not require a release paper or release film, it can be peeled off from the adhesive film and reused. In terms of irradiation with active energy rays, ionizing radiation such as X-rays, gamma rays, ultraviolet rays, or electron beams are usually used, but considering the cost of the equipment and the ease of operation, ultraviolet irradiation is sufficient. This is representative in the present invention.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 [Synthesis of rubbery polymer (A) having (meth)acryloyl group in the side chain] (i) Synthesis of polymer (a) containing hydroxyl group in the side chain Equipped with a stirrer, reflux condenser, dropping funnel, and gas introduction tube In a separable flask equipped with a thermometer, add 250 g of ethyl acetate, 250 g of butyl acrylate, and 2-hydroxyethyl acrylate.
23g, methyl methacrylate 20g, azobisisobutyronitrile 1.3g, lauryl mercaptan
After charging 0.5 g of hydroquinone and polymerizing it under refluxing ethyl acetate in a nitrogen stream for 16 hours, 0.11 g of hydroquinone was added.
g to obtain a pale yellow ethyl acetate solution of the side chain hydroxyl group-containing polymer (a).

(ii) Synthesis of unsaturated isocyanate (b) In a separable flask equipped with a stirrer, a thermometer with a gas inlet tube, a reflux condenser, and a dropping funnel, add 186 g of ethyl acetate and 174 g of 2,4-tolylene diisocyanate. Prepare (1 mol),
2-Hydroxyethyl acrylate containing 0.2 g dibutyltin dilaurate in a stream of dry air
140 g (1.2 mol) was added dropwise.

When the temperature was maintained at 60℃ and the reaction was allowed to proceed for 3 hours after the completion of the dropwise addition, it was determined that the hydroxyl group had disappeared as a result of infrared analysis, and unsaturated isocyanate was formed.
An ethyl acetate solution of (b) was obtained in pale yellow color.

125 g of unsaturated isocyanate (b) (ethyl acetate solution) was added to 498 g of side chain hydroxyl group-containing polymer (a) (ethyl acetate solution) and reacted for 6 hours at the boiling point of ethyl acetate. As a result of infrared analysis, free It was determined that the hydroxyl groups and isocyanate groups had disappeared.

Next, after distilling about 100 c.c. of ethyl acetate,
Add 200g of butyl acrylate first, then add about 450mm
Ethyl acetate was distilled out under reduced pressure of Hg, and as the flask became viscous, more butyl acrylate was added, and finally 580 g of butyl acrylate was added. Furthermore, 50 g of methyl methacrylate was added to obtain a monomer solution of a rubbery polymer (A) having a (meth)acryloyl group in the side chain as a light yellowish brown liquid with a viscosity of about 50 poise. The molecular weight of polymer (A) measured by GPC method was about 50,000.

[Synthesis of polyester (B)] In a three-necked flask equipped with a stirrer, a thermometer with a gas inlet tube, and a fractionating condenser, add 130 g of trimethylolpropane and 520 g of dipropylene glycol.
g, 702 g of adipic acid and placed in a nitrogen gas stream.
Esterification was performed at 220-230°C to synthesize a hydroxyl polyester (B) with an acid value of 4.6 and a hydroxyl value of 213.
The obtained hydroxy polyester has a light yellowish brown color,
It was in the form of a viscous syrup.

[Manufacture of adhesive tape] 100 parts by weight of a monomer solution of rubbery polymer (A) (polymer content approximately 35% by weight), 80 parts by weight of a butyl acrylate solution containing 50% by weight of polyester (B), and 2 parts by weight of benzophenone. 1 part by weight, and 2 parts by weight of dimethylaminoethanol were added to obtain a photocurable mixture.

A polyethylene terephthalate film with a thickness of 75μ and a width of 22cm is covered with 50μ thick vinyl tape on each end 1cm at a time, one end is coated with the above-mentioned photo-curing mixture, and a silicone release paper is crimped to de-air the film. Spread the mixture all over. Place this with the polyethylene terephthalate film side facing up.
20cm below the ultraviolet irradiation machine with an output of 50KW,
Passed at m/min.

When the silicon release paper was peeled off, an adhesive tape was obtained, and its physical properties were as follows.

Table 1 Adhesion: Rolling ball method (J.Dow method) 15 Adhesion strength: 180° peeling, stainless steel panel 1.6Kg/in. Holding strength: 25mm × 100mm adhesive film to 25 × 25mm
time until the weight falls under a load of 1 kg, 5 hours, Example 2 75 mol (%) of 2-ethylhexyl acrylate,
To 250 g of mixed monomers consisting of 20 moles (%) of ethyl acrylate and 5 moles (%) of 2-hydroxyethyl methacrylate, 2 g of azobisisobutyronitrile was added as a polymerization initiator, and then ethyl acetate was added.
Together with 250g of azobisisobutyronitrile, the mixture was charged into a separable flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, and polymerized for 8 hours under refluxing ethyl acetate while gradually increasing the temperature. 1 g was added and polymerization was continued for 4 hours.

0.05 g of hydroquinone was added to stop the polymerization.

The molecular weight of the obtained terpolymer was approximately 150,000.

Next, add isocyanate ethyl methacrylate to this, the number of moles (1.1 g) corresponding to the hydroxyl groups in 200 g of polymer, and dibutyltin dilaurate.
When 0.7g was charged and reacted at 60-65℃ for 3 hours,
As a result of infrared analysis, it was observed that free isocyanate groups had disappeared.

After changing to a fractionating condenser and distilling out about 100g of ethyl acetate under reduced pressure of about 400Torr, 210g of butyl acrylate was added, and the mixture was further distilled until no more ethyl acetate was distilled out. Then, 23g of acrylonitrile and 7g of acrylic acid were added. A monomer solution of a polymer (C) having a methacryloyl group in the side chain via a urethane bond was obtained, which was approximately 74 poise and was in the form of a light yellowish brown liquid.

Production of rosin-modified polyester resin 2 equipped with a stirrer, a thermometer with a gas introduction tube, and a fractionating condenser.
In a three-necked flask, add trimethylolpropane.
130 g, dipropylene glycol 520 g, WW rosin 150 g, endomethylenetetrahydrophthalic anhydride 752 g, and fumaric acid 53 g were charged, and esterification was performed at 220 to 230°C in a nitrogen gas stream to produce unsaturated polyester (D) with an acid value of 39.1. Synthesized.

It was a yellowish brown solid with viscosity.

[Manufacture and physical properties of adhesive tape]

To 100 parts by weight of monomer solution of rubbery polymer (C),
After adding 50 parts by weight of polyester (D) and uniformly dissolving it, 2 parts by weight of Darokyure #1173 manufactured by Merck & Co., Ltd. and 0.5 parts of benzoyl peroxide were added to 100 parts by weight of this mixed resin to obtain a photocurable resin.

A 50μ thick vinyl tape is applied to each 1cm end of a polyethylene terephthalate film with a thickness of 75μ and a width of 22cm, and one end is coated with the above-mentioned photocurable mixture, and a silicone release paper is pressed to remove air at the same time. The mixture was spread over the entire film.

This was placed under an ultraviolet irradiation machine with an output of 30KW with the polyethylene terephthalate film side facing upward.
20cm was passed at 2m/min.

An adhesive tape was obtained by peeling off the silicone release paper, and its physical properties were as follows.

Adhesion: Ball tack (J.Dow method) 9 180° peeling: Stainless steel panel, 1.3Kg/inch After curing for 30 minutes at 120℃, 2.1Kg/inch Holding force: 25m/m x 100m/m adhesive film
Glued to a stainless steel panel by 25 x 25 m/m, time required for the weight to fall under a load of 1 kg: 5 hours or more [Comparative example] Ethylhexyl acrylate 75 mol (%), ethyl acrylate 20 mol (%), acrylic acid 5 mol (%) 200g of monomer, 2g of azobisisobutyronitrile, 200g of ethyl acetate,
The mixture was charged into a separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas inlet tube, and the mixture was refluxed for 8 hours under refluxing ethyl acetate while gradually increasing the temperature. After adding 1 g and polymerizing for another 4 hours,
0.05 g of hydroquinone was added to stop the polymerization. The molecular weight was approximately 150,000.

Next, 70 g of a 10% ethanol solution of undecyl imidazole and 1 g of glycidyl methacrylate were added, and the mixture was stirred at 80-85° C. for 6 hours to complete the reaction.

Terpene phenol resin (product name: YS Harrier T
25 parts by weight of ``-115; manufactured by Chesai Oil & Oil Co., Ltd.'' were blended to form an adhesive, and 2 parts of Darokyur #1173 were added thereto, and the mixture was coated twice on a polyethylene terephthalate film to a thickness of 50 .mu.m, and dried.

The dry adhesive was further pressed onto release paper treated with silicone resin, and the polyethylene terephthalate film was placed 20cm under an ultraviolet lamp with an output of 30KW for 2m/20cm.
Passed it in minutes.

The physical properties of the adhesive tape were as follows, and were not as good as the present invention.

Adhesiveness; Ball Tack 13 180℃ peeling; stainless steel panel 0.35Kg/inch 0.4Kg/inch after processing at 120℃ for 30 minutes Holding power: Same as before, 10 minutes or less

Claims (1)

[Claims] 1. A rubbery polymer having an acryloyl group and/or methacryloyl group in the side chain via a urethane bond, monomers that can dissolve the rubbery polymer, and are compatible with the rubbery polymer and useful for tackification. 1. A method for producing an adhesive tape, which comprises coating a base material with a mixture of oligomers and irradiating the mixture with active energy rays in the absence of air.