JP6830281B2 - Pressure-sensitive adhesive and its manufacturing method - Google Patents

Description

The present invention belongs to the field of optical display, and particularly relates to an optical pressure-sensitive adhesive for bonding displays and a method for producing the same.

With the widespread application and high-speed development of optical displays, the demand for optical pressure-sensitive adhesives is increasing. Acrylic resin is often used as one of the pressure-sensitive adhesives, and it is widely applied because it has various advantages as follows.
1. Shows high adhesive strength to transparent materials such as PET optical film or glass.
2. The appearance is colorless and transparent, and it has good weather resistance.
3. No additives are required and the recipe is simple.
4. A pressure-sensitive adhesive that meets various different performance requirements can be produced by copolymerization and cross-linking.

However, with the rapid development of electronic products, there are certain restrictions on acrylic resin adhesives. For example, when applied to a given application, it is necessary to use an adhesive having a low dielectric constant (generally, Dk is 2 to 3 under the condition of 1 kHz to 1 MHz), and conventional acrylic resins have a double bond and a high dielectric constant. It is difficult to meet this requirement because it has.

The present invention is proposed in consideration of such a thing.

A first object of the present invention is to provide a pressure-sensitive adhesive which has a low dielectric constant under the conditions of 1 kHz to 1 MHz and has advantages such as high peel strength and high transmittance, and thus is expected to have a wide application foreground. To do.

A second object of the present invention provides a method for producing the pressure-sensitive adhesive, and since the method is simple in process and easy to produce, it is easy to promote a new product.

In order to achieve the above object, the present invention provides the following technical means.

Obtained by polymerizing one or more acrylate monomers and oligomers under the action of a photoinitiator.
The acrylate monomer is a saturated alcohol acrylate or a saturated alcohol alkyl acrylate.
In the polymer, the weight ratio of the acrylate monomer is 10% or more, preferably 15% or more, more preferably 20% or more.
The oligomer has a molecular weight of 20,000 or more, and is selected from acrylate-based prepolymers, epoxy prepolymers, silicone prepolymers, polyurethane prepolymers, polyether prepolymers, polyhydroxy polyolefin oligomers, polybutadiene prepolymers, and fluorine-modified prepolymers. One or more types of pressure-sensitive adhesives.

The present invention solves the technical problem that the permittivity cannot be applied to new technical products, and the solution principle of this problem is to reduce the permittivity mainly by reducing the number of double bonds in the adhesive. ..

It is not possible to obtain a sufficient effect simply by reducing the number of double bonds without considering other factors after repeated actual studies, and mainly the peel strength is very low and there is no practical value, or the transmittance, etc. We have found that other performance is significantly reduced. In order to obtain an adhesive having practical value, it is necessary to copolymerize a predetermined type and a predetermined content of an acrylate monomer and a predetermined type of prepolymer in addition to reducing the number of double bonds.

According to the research by the inventors, the adhesive produced by the above recipe shows excellent overall performance, the peel strength is maintained at 8 N / 25 mm or more (180 °), and the dielectric constant at 1 kHz to 1 MHz is 2-3. The transmittance at a wavelength of 550 nm is 99% or more.

The above invention can be further improved as follows to obtain more technical effects.

Preferably, the alkyl is selected from C1-C10 alkyls, preferably C1-C6 alkyls. That is, methyl, ethyl, propyl, butyl, isobutyl and the like may be used as the substituent of acrylic acid.

Preferably, the saturated alcohol is selected from C1 to C18 saturated monohydric alcohols or polyhydric alcohols, preferably C2 to C8 saturated monohydric alcohols or polyhydric alcohols, more preferably C4 to C8 saturated monohydric alcohols or. It is selected from polyhydric alcohols. For example, methanol, ethanol, propanol, propylene glycol, n-butanol, isobutanol, butanediol, n-octanol, isooctanol, hexadecyl alcohol, stearyl alcohol and the like may be used. Here, the saturated alcohol refers to the saturated alcohol in all the esters used above, but the type of the saturated alcohol of each compound is independent, that is, one of the above-mentioned saturated alcohols is independently selected. You need to be careful.

It is the type of monomer that most affects the peel strength of the adhesive, followed by the dielectric constant.

In order to obtain high peel strength and low dielectric constant, the acrylate monomer is preferably a mixture of 2-ethylhexyl acrylate and 4-hydroxybutyl acrylate, and the weight ratio of the two is 1: 1 or less, that is, 4-hydroxy. It is preferable that the dose of butyl acrylate is lower than that of 2-ethylhexyl acrylate.

Preferably, the oligomer is one or a mixture of two in an acrylate-based prepolymer, a polyurethane prepolymer.

Preferably, the molecular weight of the oligomer is 20000-40,000, or 30,000-60,000, or 40,000-70000.

It is the type and molecular weight of the oligomer that most affects the peel strength of the adhesive, and if rationally selected, a much higher peel strength than the conventional product can be obtained.

Preferably, the weight ratio of the oligomer is 20% or more, preferably 25% or more, and more preferably 30% or more.

The weight ratio of the oligomer has a significant effect on the peel strength and dielectric constant of the adhesive, preferably 20% or more, eg 20%, 25%, 30%, 35%, 40%, 45%, 50%. 55%, 60%, 65%, 70% and the like.

Crosslinkers, adhesives, plasticizers, antistatics, fabric softeners, colorants, oxidants, leveling agents, light stabilizers, defoamers, in the case of polymerization to improve the stability of the adhesive. One or more additives selected from stabilizers and preservatives may be introduced in appropriate amounts.

Preferably, the content of the additive is 10 to 50 wt%.

Preferably, the additive comprises an adhesion-imparting agent.

Preferably, the additive includes an adhesion-imparting agent, a light stabilizer, and an antifoaming agent.

As the various additives, ordinary ones may be used, and in the present invention, the influence on the peel strength and the dielectric constant differs depending on the type and the dose.

Preferably, the adhesive-imparting agent is a terpene phenol resin, and the content of the adhesive-imparting agent is 15 wt% or more, preferably 20 wt% or more, and more preferably 25 wt% or more.

If the dose and type of adhesive are not appropriate, the dielectric constant will increase, the stability will decrease, and the peel strength will not be significantly improved. To avoid this, select the above types and doses.

Preferably, the light stabilizer is selected from the phenoxytriazine type, and the content thereof is 0.1 to 0.3 wt%, preferably 0.1 to 0.2 wt%.

Preferably, the defoaming agent is selected from polysiloxane, and the content thereof is 0.1 to 0.3 wt%, preferably 0.1 to 0.2 wt%.

Preferably, the cross-linking agent is a polyhydric alcohol polyvalent acrylate and / or a polyhydric alcohol polyvalent methacrylate, indicating that the "multivalent" before the acid here has a plurality of ester groups.

Preferably, the polyhydric alcohol is selected from glycols, trihydric alcohols, tetrahydric alcohols or polyethylene glycols, preferably saturated alcohols or cycloalkyl alcohols, more preferably 1,4-butanediol, 1,6-hexanediol, and more. 1,9-Nonandiol, Tripropylene Glycol, Tricyclodecanedimethanol, 1,10-Decandiol, Polyethylene Glycol 200, Polyethylene Glycol 400, Trimethylol Propane, Ditrimethylol Propane, Ethanolated Pentaerythritol, Pentaerythritol, Dipenta One or more selected from among erythritols.

Preferably, the polymer has a weight ratio of the cross-linking agent of 0.1 to 3 wt%.

In addition, since the pressure-sensitive adhesive of the present invention can utilize the existing hot press and curing process, the cost of upgrading the product (including equipment replacement, process condition control, worker training, etc.) is significantly reduced. it can.

Among them, in the case of polymerization, the photoinitiator is benzyldimethyl ether, dialkoxyacetophenone, methylbenzoylformate, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-benzene-1-acetone, 2 -Methyl-1- (4-methylthiophenyl) -2-morpholin-1-acetone, 2-phenylbenzyl-2-dimethylamine-1- (4-morpholinbenzyl) butanone, 2,4,6-trimethylbenzoylphenylphosphine , 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-triethylmethylbenzoylphenylphosphonate, benzophenone, 4,4'-bis (diethylamino) benzophenone, 2-isopropylthioxanthone, 4-dimethylamino-ethylbenzoate It is one or a mixture of two or more of the above, preferably a mixture of 2,4,6-trimethylbenzoylphenylphosphine and methylbenzoylformate, preferably in a weight ratio of 1 to 2: 1. Is.

As described above, as compared with the conventional technique, the following technical effects are obtained according to the present invention.
(1) The overall performance of the adhesive (peeling strength, dielectric constant, transmittance, stability of dielectric constant, etc.) is improved.
(2) The field of application of adhesives is wider.
(3) The demand for the production process is low.

Hereinafter, in order to more clearly explain the specific embodiment of the present invention or the technical means of the prior art, the drawings required for the description of the specific embodiment or the prior art will be briefly described. It goes without saying that the drawings are only some embodiments of the present invention and that those skilled in the art can conceive of other drawings based on these drawings without creative labor.

It is a figure which shows the change of the dielectric constant of the adhesive obtained in the Example and the comparative example of this invention at different frequencies.

Hereinafter, the technical means of the present invention will be clearly described with reference to the drawings and specific embodiments, but for those skilled in the art, the examples described below are not all examples but only a part of the present invention. , It is understood that it is used to illustrate the invention and does not limit the scope of the invention. Based on the examples in the present invention, all other examples obtained by those skilled in the art without creative labor are also included in the scope of protection of the present invention. In the examples, normal conditions or conditions recommended by the manufacturer are adopted unless explicitly stated otherwise. Unless the manufacturer is specified, the reagents and equipment used are normal products that are commercially available.

The present invention solves the technical problem that the permittivity cannot be applied to new technical products, and the solution principle of this problem is to reduce the permittivity mainly by reducing the number of double bonds in the adhesive. .. It is not possible to obtain a sufficient effect simply by reducing the number of double bonds without considering other factors after repeated actual studies, and mainly the peel strength is very low and there is no practical value, or the transmittance, etc. We have found that other performance is significantly reduced. In order to obtain an adhesive having practical value, it is necessary to reduce the number of double bonds and copolymerize a predetermined type and a predetermined content of an acrylate monomer with a predetermined type of prepolymer. The basic method is as follows.

Obtained primarily by polymerizing one or more acrylate monomers and oligomers under the action of photoinitiators.
The acrylate monomer is a saturated alcohol acrylate or a saturated alcohol alkyl acrylate.
In the polymer, the weight ratio of the acrylate monomer is 10% or more, preferably 15% or more, more preferably 20% or more.
The oligomer has a molecular weight of 20,000 or more, and is selected from acrylate-based prepolymers, epoxy prepolymers, silicone prepolymers, polyurethane prepolymers, polyether prepolymers, polyhydroxy polyolefin oligomers, polybutadiene prepolymers, and fluorine-modified prepolymers. One or more types.

Based on this, the present invention was introduced by optimizing the types and doses of monomers and oligomers, and at the same time optimizing the types and amounts of additives, resulting in better overall performance. It is a street.

The alkylacrylic acid is an alkyl-substituted acrylic acid of C1 to C10, preferably an alkyl-substituted acrylic acid of C1 to C6.

Preferably, the saturated alcohol is selected from C1 to C18 saturated monohydric alcohols or polyhydric alcohols, preferably C2 to C8 saturated monohydric alcohols or polyhydric alcohols, preferably C4 to C8 saturated monohydric alcohols or polyhydric alcohols. It is selected from valent alcohol.

It is preferable that the saturated acrylate monomer is a mixture of 4-hydroxybutyl acrylate and 2-ethylhexyl acrylate, and the weight ratio of the two is 1: 1 or less.

Preferably, the molecular weight of the oligomer is 20000-40,000, or 30,000-60,000, or 40,000-70000.

Preferably, the weight ratio of the oligomer is 20% or more, preferably 25% or more, and more preferably 30% or more.

Preferably, in the case of the polymerization, in the cross-linking agent, adhesive-imparting agent, plasticizer, antistatic agent, softener, colorant, antioxidant, leveling agent, light stabilizer, defoaming agent, stabilizer Japanese preservative. Introduce one or more additives selected from the above in appropriate amounts.

Preferably, the content of the additive is 10 to 50 wt%.

Preferably, the additive comprises an adhesion-imparting agent.

Preferably, the additive comprises an adhesion-imparting agent, a light stabilizer, an antifoaming agent.

Preferably, the adhesion-imparting agent is selected from the terpene phenol resin, and the content of the adhesion-imparting agent is 15 wt% or more, preferably 20 wt% or more, and more preferably 25 wt% or more.

Preferably, the light stabilizer is selected from the phenoxytriazine type, and the content thereof is 0.1 to 0.3 wt%, preferably 0.1 to 0.2 wt%.

Preferably, the defoaming agent is selected from polysiloxane, and the content thereof is 0.1 to 0.3 wt%, preferably 0.1 to 0.2 wt%.

Preferably, the cross-linking agent is a polyhydric alcohol acrylate and / or a polyhydric alcohol methacrylate.

Preferably, the polyhydric alcohol is selected from glycols, trihydric alcohols, tetrahydric alcohols or polyethylene glycols, preferably saturated alcohols or cycloalkyl alcohols, more preferably 1,4-butanediol, 1,6-hexane. Diol, 1,9-nonanediol, tripropylene glycol, tricyclodecanedimethanol, 1,10-decanediol, polyethylene glycol 200, polyethylene glycol 400, trimethylolpropane, ditrimethylolpropane, ethoxylated pentaerythritol, pentaerythritol, One or more selected from dipentaerythritol.

Preferably, in the polymer, the weight ratio of the cross-linking agent is 0.1 to 3 wt%.

Preferably, the photoinitiator is 2,4,6-trimethylbenzoylphenylphosphine and / or methylbenzoylformate, preferably a mixture of both, preferably a weight ratio of both 1 to 2: 1. ..

Based on the above, the present invention provides the following examples.

Examples 1-6
Prepare the adhesive.
The recipe is shown in Table 1.

The manufacturing method is as follows.

The liquid pressure-sensitive binder composition can be obtained by sufficiently stirring and mixing the components and vacuum suctioning, and the composition can be directly applied to a substrate and cured by an ultraviolet irradiation method.

Comparative Example 1
It is different from Example 1 that an acrylate-based prepolymer having a molecular weight of 15,000 is used instead of the prepolymer.

Comparative Examples 2 to 6
The recipes of Comparative Examples 2 to 6 are shown in Table 2, and the production method is the same as that of Example 1.

The performance of the adhesives of the above Examples and Comparative Examples as a whole was measured and shown in Tables 3 and 4 as shown below, and the peel strength of the adhesives obtained in Examples 3 to 16 was all maintained at 8N or more. The dielectric constant at 1 kHz to 1 MHz is maintained at 2 to 3, and the transmittance at a wavelength of 550 nm is 99% or more.

Further, the adhesive of the present invention stabilizes the dielectric constant within a wide frequency range and has a change tendency as in Example 1 and Comparative Examples 3 and 5, and is shown in FIG.

As described above, the adhesive of the present invention has excellent overall performance.

Finally, each of the above examples is merely a technical means for explaining the present invention, and does not limit the scope of the invention. Although the present invention has been described in detail by each of the above Examples, those skilled in the art will be modified or equivalent to the technical features of all or a part of the technical means described in each of the above Examples without departing from the spirit of the present invention. Substitutions are added, and those modifications and substitutions are also included in the scope of protection of the present invention.

(Additional note)
(Appendix 1)
Obtained by polymerizing one or more acrylate monomers and oligomers under the action of a photoinitiator.
The acrylate monomer is a saturated alcohol acrylate or a saturated alcohol alkyl acrylate.
In the polymer, the weight ratio of the acrylate monomer is 10% or more, preferably 15% or more, more preferably 20% or more.
The oligomer has a molecular weight of 20,000 or more, and is selected from acrylate-based prepolymers, epoxy prepolymers, silicone prepolymers, polyurethane prepolymers, polyether prepolymers, polyhydroxy polyolefin oligomers, polybutadiene prepolymers, and fluorine-modified prepolymers. A pressure-sensitive adhesive characterized by being one or more types.

(Appendix 2)
The alkyl in the saturated alcohol alkyl acrylate is selected from the alkyls of C1 to C10, preferably selected from the alkyls of C1 to C6.
Preferably, the saturated alcohol acrylate and the saturated alcohol in the saturated alcohol alkyl acrylate are independently selected from the saturated monohydric alcohol or polyhydric alcohol of C1 to C18, and preferably the saturated monohydric alcohol or polyhydric alcohol of C2 to C8. It is selected from alcohols, more preferably from C4-C8 saturated monohydric or polyhydric alcohols.
Preferably, the pressure-sensitive adhesion according to Appendix 1, wherein the acrylate monomer is a mixture of 2-ethylhexyl acrylate and 4-hydroxybutyl acrylate, and the weight ratio of the two is preferably 1: 1 or less. Agent.

(Appendix 3)
The oligomer is one or a mixture of two in an acrylate-based prepolymer and a polyurethane prepolymer.
Preferably, the oligomer has a molecular weight of 20000-40,000, or 30,000-60,000, or 40,000-70000.
The pressure-sensitive adhesive according to Appendix 1, wherein the weight ratio of the oligomer is preferably 20% or more, preferably 25% or more, and more preferably 30% or more.

(Appendix 4)
In the case of the polymerization, 1 in the cross-linking agent, adhesive-imparting agent, plasticizer, antistatic agent, softener, colorant, antioxidant, leveling agent, light stabilizer, defoaming agent, stabilizer and preservative. Introduce seeds or multiple types of additives in appropriate amounts,
Preferably, the pressure-sensitive adhesive according to any one of Appendix 1 to 3, wherein the content of the additive is 10 to 50 wt%.

(Appendix 5)
The pressure-sensitive adhesive according to Appendix 4, wherein the additive contains an adhesive-imparting agent.

(Appendix 6)
The pressure-sensitive adhesive according to Appendix 4, wherein the additive contains an adhesive, a light stabilizer, and an antifoaming agent.

(Appendix 7)
The adhesive-imparting agent is preferably selected from the terpene phenol resin, and the content of the adhesive-imparting agent is 15 wt% or more, preferably 20 wt% or more, and more preferably 25 wt% or more.
Preferably, the light stabilizer is selected from the phenoxytriazine type, and the content thereof is 0.1 to 0.3 wt%, preferably 0.1 to 0.2 wt%.
Preferably, the defoaming agent is selected from polysiloxane, and the content thereof is 0.1 to 0.3 wt%, preferably 0.1 to 0.2 wt%. The pressure sensitive adhesive described in.

(Appendix 8)
The cross-linking agent is a polyhydric alcohol polyvalent acrylate and / or a polyhydric alcohol polyvalent methacrylate.
Preferably, the polyhydric alcohol in the cross-linking agent is selected from glycol, trihydric alcohol, tetrahydric alcohol or polyethylene glycol, preferably from saturated alcohol or cycloalkyl alcohol, and more preferably 1,4-butane. Diol, 1,6-hexanediol, 1,9-nonanediol, tripropylene glycol, tricyclodecanedimethanol, 1,10-decanediol, polyethylene glycol 200, polyethylene glycol 400, trimethylolpropane, ditrimethylolpropane, ethoxyl One or more selected from pentaerythritol, pentaerythritol and dipentaerythritol.
Preferably, the pressure-sensitive adhesive according to Appendix 4, wherein the cross-linking agent has a weight ratio of 0.1 to 3 wt% in the polymer.

(Appendix 9)
The method for producing a pressure-sensitive adhesive according to any one of Supplementary Notes 1 to 8.
A production method characterized in that all raw materials are mixed according to a recipe and polymerized under the action of a photoinitiator.

(Appendix 10)
The photoinitiators are benzyl dimethyl ether, dialkoxyacetophenone, methylbenzoylformate, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-benzene-1-acetone, 2-methyl-1- (4-methylthio). Phenyl) -2-morpholin-1-acetone, 2-phenylbenzyl-2-dimethylamine-1- (4-morpholinbenzyl) butanone, 2,4,6-trimethylbenzoylphenylphosphine, 2,4,6-trimethylbenzoyl One or two or two of diphenylphosphine oxide, 2,4,6-triethylmethylbenzoylphenylphosphonate, benzophenone, 4,4'-bis (diethylamino) benzophenone, 2-isopropylthioxanthone, 4-dimethylamino-ethylbenzoate Addendum 9 characterized in that it is a mixture of species or more, preferably a mixture of 2,4,6-trimethylbenzoylphenylphosphine and methylbenzoylformate, and preferably has a weight ratio of 1 to 2: 1. The method for producing a pressure-sensitive adhesive according to.

Claims (10)

Obtained by polymerizing one or more acrylate monomers and oligomers under the action of a photoinitiator.
The acrylate monomer is 2-ethylhexyl acrylate, isodecyl acrylate, or lauryl acrylate,
In the polymer, the weight ratio of said acrylate monomer is over 10% or more,
The molecular weight of the oligomer is 20,000 or more, Ri Oh acrylate-based prepolymer over,
In the case of the polymerization, one of a cross-linking agent, an adhesion-imparting agent, a plasticizer, an antistatic agent, a softener, a colorant, an antioxidant, a leveling agent, a light stabilizer, a defoaming agent, a stabilizer and a preservative. Or introduce multiple types of additives in appropriate amounts and
The content of the additive is 10 to 50 wt%.
The additive contains an adhesive, and the pressure-sensitive adhesive is a terpene phenol resin . A mixture of pre-Symbol acrylate monomer is 2-ethylhexyl acrylate and 4-hydroxybutyl acrylate, and the weight ratio therebetween is 1: pressure-sensitive adhesive of claim 1, wherein the 1 or less der Turkey. The molecular weight of the previous Symbol oligomer is 20,000 to 40,000, or from 30,000 to 60,000, or a 40,000 to 70,000,
The pressure sensitive adhesive of claim 1 the weight ratio before Symbol oligomer characterized in that it is a 20% or more. The pressure-sensitive adhesive according to claim 1 , wherein the additive contains a light stabilizer and an antifoaming agent. The content of the previous SL adhesion-imparting agent is the 15 wt% or more,
Are those before Symbol light stabilizer is selected from phenoxy triazine, the content thereof is 0.1 to 0.3%,
It is those before Symbol defoamer is selected from polysiloxane pressure sensitive adhesive of claim 1, wherein the content thereof is 0.1 to 0.3%. The pressure sensitive adhesive of claim 1, wherein the crosslinking agent is a polyhydric alcohol polyvalent acrylates, and / or polyhydric alcohols polyvalent methacrylate. The method for producing a pressure-sensitive adhesive according to any one of claims 1 to 6 .
A production method characterized in that all raw materials are mixed according to a recipe and polymerized under the action of a photoinitiator. The photoinitiators are benzyl dimethyl ether, dialkoxyacetophenone, methylbenzoylformate, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-benzene-1-acetone, 2-methyl-1- (4-methylthio). Phenyl) -2-morpholin-1-acetone, 2-phenylbenzyl-2-dimethylamine-1- (4-morpholinbenzyl) butanone, 2,4,6-trimethylbenzoylphenylphosphine, 2,4,6-trimethylbenzoyl One or two or two of diphenylphosphine oxide, 2,4,6-triethylmethylbenzoylphenylphosphonate, benzophenone, 4,4'-bis (diethylamino) benzophenone, 2-isopropylthioxanthone, 4-dimethylamino-ethylbenzoate method for producing a pressure sensitive adhesive according to claim 7, characterized in that a mixture of more species. The method for producing a pressure-sensitive adhesive according to claim 7, wherein the photoinitiator is a mixture of 2,4,6-trimethylbenzoylphenylphosphine and methylbenzoylformate. The method for producing a pressure-sensitive adhesive according to claim 9, wherein the weight ratio of the 2,4,6-trimethylbenzoylphenylphosphine to the methylbenzoylformate is 1 to 2: 1.