KR20200048601A - Adhesive composition and adhesive comprising cured product thereof - Google Patents

Abstract

The present invention relates to an adhesive with improved step-fillability and optical properties, and to an adhesive composition which can implement the same. The adhesive composition comprises: a photo-reactive urethane resin; a photo-crosslinking agent including a benzophenone group-containing (meth)acrylate compound; and a monomer mixture.

Description

An adhesive comprising an adhesive composition and a cured product thereof {ADHESIVE COMPOSITION AND ADHESIVE COMPRISING CURED PRODUCT THEREOF}

The present invention relates to an adhesive comprising an adhesive composition and a cured product thereof.

The adhesive is used to attach a number of members included in the display device. Such a pressure sensitive adhesive is specifically used for adhesion between members of a device having a multi-layered structure, or used for sealing parts requiring moisture resistance. In addition, the pressure-sensitive adhesive may be made of a photocurable pressure-sensitive adhesive composition that is crosslinked with ultraviolet light, electron beam, or the like.

As a photo-curable adhesive used in a display device, a urethane-based adhesive having excellent shock absorption and durability is used. However, the urethane-based pressure-sensitive adhesive having a high storage modulus has a high gel content, and thus it is not easy to secure an excellent step landfill property. In addition, the urethane-based adhesive having a low gel content has a problem in that it is not easy to realize excellent optical properties.

Therefore, there is a need for a technology capable of realizing a urethane-based pressure-sensitive adhesive having excellent level embedding properties and optical properties.

The present invention seeks to provide a pressure-sensitive adhesive composition having improved step buried property and optical properties and a pressure-sensitive adhesive composition capable of implementing the same.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

One embodiment of the present invention, a copolymer comprising a polymerization unit derived from a first mixture comprising a polyol and a diisocyanate-based compound; And a photoreactive end group derived from a compound represented by the following Chemical Formula 1 and attached to the terminal of the copolymer; A photo-crosslinking agent comprising a benzophenone group-containing (meth) acrylate compound; And a monomer mixture comprising an alkyl group-containing (meth) acrylate monomer, a cycloalkyl group-containing (meth) acrylate monomer, and a polar group-containing (meth) acrylate monomer; to provide an adhesive composition comprising:

[Formula 1]

In Chemical Formula 1, n is an integer of 2 to 12.

In addition, an exemplary embodiment of the present invention provides an adhesive comprising a cured product of the adhesive composition.

The pressure-sensitive adhesive composition according to an exemplary embodiment of the present invention may provide a pressure-sensitive adhesive having excellent optical properties and stepped buried properties.

The pressure-sensitive adhesive according to an exemplary embodiment of the present invention has an advantage of excellent optical properties and step fillability.

The effects of the present invention are not limited to the above-described effects, and the effects not mentioned will be clearly understood by those skilled in the art from the present specification and the accompanying drawings.

Throughout the present specification, when a part “includes” a certain component, this means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

Throughout this specification, when one member is positioned “on” another member, this includes not only the case where one member abuts another member, but also the case where another member exists between the two members.

Throughout the present specification, the unit “parts by weight” may mean a ratio of weight between each component.

Throughout this specification, "(meth) acrylate" is used to mean acrylate and methacrylate collectively.

Throughout this specification, “A and / or B” means “A and B, or A or B”.

Throughout the present specification, the term "monomer unit" may mean a form in which a monomer is reacted in a polymer, and specifically, the polymer is subjected to a polymerization reaction, and thus a skeleton of the polymer, for example, a main chain or a side chain It may mean the form forming.

Throughout this specification, the “weight average molecular weight” and “number average molecular weight” of a compound can be calculated using the molecular weight and molecular weight distribution of the compound. Specifically, tetrahydrofuran (THF) and a compound are prepared in a 1 ml glass bottle to prepare a sample sample having a compound concentration of 1 wt%, and a standard sample (polystyrene, polystryere) and a sample sample are filtered (pore size). Is filtered through 0.45 mm), and injected into a GPC injector, comparing the elution time of the sample sample with the calibration curve of the standard sample to obtain the molecular weight and molecular weight distribution of the compound. At this time, Infinity II 1260 (Agilient Co.) can be used as a measuring instrument, the flow rate can be set to 1.00 mL / min, and the column temperature can be set to 40.0 ° C.

Throughout the present specification, the viscosity of the compound may be a value measured with a Brookfield viscometer at a temperature of 25 ° C.

Hereinafter, the present specification will be described in more detail.

One embodiment of the present invention, a copolymer comprising a polymerization unit derived from a first mixture comprising a polyol and a diisocyanate-based compound; And a photoreactive end group derived from a compound represented by the following Chemical Formula 1 and attached to the terminal of the copolymer; A photo-crosslinking agent comprising a benzophenone group-containing (meth) acrylate compound; And a monomer mixture comprising an alkyl group-containing (meth) acrylate monomer, a cycloalkyl group-containing (meth) acrylate monomer, and a polar group-containing (meth) acrylate monomer; to provide an adhesive composition comprising:

[Formula 1]

In Chemical Formula 1, n is an integer of 2 to 12.

The pressure-sensitive adhesive composition according to an exemplary embodiment of the present invention may provide a pressure-sensitive adhesive having excellent optical properties and stepped buried properties.

According to an exemplary embodiment of the present invention, a urethane-based copolymer may be formed using the first mixture comprising the polyol and the diisocyanate-based compound. Specifically, as the reaction proceeds between the isocyanate group of the diisocyanate-based compound and the hydroxyl group of the polyol, a urethane bond is formed, and a urethane-based copolymer having isocyanate groups at both ends may be formed. That is, the copolymer may be a urethane-based copolymer, and the copolymer may include a polymerization unit formed through the reaction of a polyol and a diisocyanate-based compound. In addition, the main chain of the copolymer may include a polymerization unit formed through the reaction of a polyol and a diisocyanate-based compound.

According to an exemplary embodiment of the present invention, the number average molecular weight of the polyol may be 500 g / mol or more and 6,000 g / mol or less. Specifically, the number average molecular weight of the polyol is 700 g / mol or more and 5,500 g / mol or less, 1,000 g / mol or more and 5,000 g / mol or less, 1,500 g / mol or more, 4,000 g / mol or less, 2,000 g / mol or more and 3,000 g / mol or less. By adjusting the number average molecular weight of the polyol to the above-described range, the weight average molecular weight of the photoreactive urethane resin can be adjusted to an appropriate range. Specifically, the weight average molecular weight of the photoreactive urethane-based resin may be adjusted to 30,000 g / mol or more and 100,000 g / mol or less. By using a photoreactive urethane resin having a weight average molecular weight in the above-described range, it is possible to provide an adhesive composition capable of realizing an adhesive with improved durability. In addition, the pressure-sensitive adhesive composition comprising a photoreactive urethane-based resin having a weight-average molecular weight in the above-described range can realize an adhesive having improved storage modulus and step filling property.

According to an exemplary embodiment of the present invention, the polyol may include two or more hydroxy groups, and specifically, the polyol may include a diol containing two hydroxy groups. More specifically, the polyol may include at least one of polycarbonate diol, polycaprolactone diol, polyester diol, and polyetherdiol. However, the type of the polyol is not limited to those described above, and the type of the polyol may be appropriately selected according to the application in which the pressure-sensitive adhesive is used.

According to an exemplary embodiment of the present invention, the diisocyanate-based compound is bis (isocyanatomethyl) cyclohexane, methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isopron diisocyanate, metaxyl Ethylene diisocyanate, dicyclohexylmethane diisocyanate, and tetramethyl xylene diisocyanate. However, the type of the diisocyanate-based compound is not limited to those described above.

According to an exemplary embodiment of the present invention, the content of the diisocyanate-based compound may be 5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the polyol. Specifically, the content of the diisocyanate-based compound contained in the mixture is 5 parts by weight or more and 30 parts by weight or less, 7 parts by weight or more and 28 parts by weight or less, 10 parts by weight or more and 25 parts by weight or less, based on 100 parts by weight of the polyol, It may be 15 parts by weight or more and 20 parts by weight or less, 7 parts by weight or more and 13 parts by weight or less, 18 parts by weight or more and 22 parts by weight or less, or 25 parts by weight or more and 30 parts by weight or less.

By adjusting the content of the diisocyanate-based compound to the above-described range, the urethane-based copolymer can be stably formed. In addition, by adjusting the content of the diisocyanate-based compound, it is possible to control the weight average molecular weight of the copolymer. Through this, the weight average molecular weight of the photoreactive urethane resin can be easily controlled. In addition, by adjusting the content of the diisocyanate-based compound, it is possible to control the content of the compound represented by Formula 1 in the composition used to prepare the photoreactive urethane-based resin.

According to an exemplary embodiment of the present invention, the ratio of the number of moles of the polyol to the number of moles of the diisocyanate-based compound may be adjusted to 1: 2. Through this, a copolymer derived from the polyol and diisocyanate-based compound can be stably formed.

According to an exemplary embodiment of the present invention, the photoreactive urethane resin may include a photoreactive end group derived from the compound represented by Chemical Formula 1. Specifically, the photoreactive end group may be bonded to both ends of the main chain of the urethane-based copolymer prepared using the first mixture containing the polyol and the diisocyanate-based compound.

According to an exemplary embodiment of the present invention, a photoreactive end group derived from the compound represented by Chemical Formula 1 may be represented by Chemical Formula 2 below.

[Formula 2]

In Formula 1 and Formula 2, n may be an integer of 2 to 12. Specifically, n may be an integer from 2 to 10, an integer from 3 to 8, an integer from 4 to 6, or an integer from 2 to 6. When the n in the formula (1) is within the above-described range, the reaction of the compound represented by the formula (1) and the urethane-based copolymer may be stably performed. Through this, a photoreactive urethane-based resin can be effectively produced. In addition, by adjusting the n in the above-described range in the formula (1), it is possible to effectively improve the photoreactivity of the photoreactive urethane resin produced.

According to an exemplary embodiment of the present invention, the photoreactive urethane-based resin may have a structure represented by the following Chemical Formula 3.

[Formula 3]

A-B-A

In Chemical Formula 3, A refers to a photoreactive end group represented by Chemical Formula 2, and B refers to a main chain comprising a polymerization unit derived from the polyol and diisocyanate-based compound.

According to an exemplary embodiment of the present invention, the photoreactive urethane-based resin is a polymer of the second mixture comprising the copolymer and the compound represented by Formula 1, and the content of the compound represented by Formula 1 is the copolymer 100 It may be 0.5 parts by weight or more and 15 parts by weight or less based on parts by weight.

According to an exemplary embodiment of the present invention, the hydroxyl group at the end of the substituent located on the benzene ring of the compound represented by Formula 1 is polymerized to react with the isocyanate group located at the end of the urethane-based copolymer, and the terminal group represented by Formula 2 A polymer bound to the urethane-based copolymer may be formed.

According to an exemplary embodiment of the present invention, the photoreactive urethane-based resin having a photoreactive end group derived from Chemical Formula 1 bonded to both ends performs crosslinking reaction of monomers included in the pressure-sensitive adhesive composition and / or crosslinking reaction with monomers. It can be performed stably. In addition, by using the photoreactive urethane-based resin, it is possible to implement an adhesive composition capable of producing an adhesive having excellent adhesive properties and improved optical properties.

According to an exemplary embodiment of the present invention, the content of the compound represented by Formula 1 contained in the first mixture is 0.5 part by weight or more and 15 parts by weight or less, 1 part by weight or more and 12.5 parts by weight based on 100 parts by weight of the copolymer Or less, 2.5 parts by weight or more and 10 parts by weight or less, 5 parts by weight or more and 7.5 parts by weight or less, 0.5 parts by weight or more and 7 parts by weight or less, 0.5 parts by weight or more and 3 parts by weight or less, or 4.5 parts by weight or more and 8.5 parts by weight or less By adjusting the content of the compound represented by Formula 1 to the above-described range, the polymerization reaction with the hydroxy group present in the compound represented by Formula 1 and the isocyanate group located at the end of the urethane-based copolymer can be stably performed. In addition, when the content of the compound represented by the formula (1) is within the above-described range, the pressure-sensitive adhesive composition comprising the photoreactive urethane-based resin can implement a pressure-sensitive adhesive with improved step filling and optical properties.

According to an exemplary embodiment of the present invention, the weight of the copolymer may be substantially the same as the weight of the mixture containing the polyol and the diisocyanate-based compound. Specifically, the weight of the copolymer may be the sum of the weights of the polyol and diisocyanate-based compound.

According to an exemplary embodiment of the present invention, the compound represented by Chemical Formula 1 may be formed through the addition reaction of a hydroxyl group-containing benzophenone with a hydroxyl group alcohol. The hydroxy group-containing benzophenone may include at least one of 2-hydroxybenzophenone, 3-hydroxybenzophenone and 4-hydroxybenzophenone. Considering the efficiency of the addition reaction with the alcohol, the reactivity of the hydroxy group of the compound represented by the formula (1) with the isocyanate group at the terminal of the urethane-based copolymer, using 4-hydroxybenzophenone as the hydroxy group-containing benzophenone It may be desirable.

In addition, the alcohol used to prepare the compound represented by Formula 1 may include at least one of ethylene carbonate, chlorohexanol and chlorobutanol, but is not limited to the type of the alcohol.

According to an exemplary embodiment of the present invention, when 4-hydroxybenzophenone is used as the hydroxy group-containing benzophenone, and ethylene carbonate is used as the alcohol, the compound represented by Formula 1 may be formed through the following Reaction Scheme 1 Can be.

[Scheme 1]

According to an exemplary embodiment of the present invention, the second mixture comprising the copolymer and the compound represented by Chemical Formula 1 further includes a diluting monomer, and the content of the diluting monomer is 100 parts by weight of the copolymer It may be 50 parts by weight or more and 300 parts by weight or less, 100 parts by weight or more and 150 parts by weight or less, or 70 parts by weight or more and 250 parts by weight or less. By adjusting the content of the diluting monomer to the above-described range, the reaction of the copolymer and the compound represented by Formula 1 can be stably performed.

According to an exemplary embodiment of the present invention, the dilution monomer used in the art may be used without limitation, and for example, ethylhexyl acrylate may be used as the dilution monomer.

According to an exemplary embodiment of the present invention, the weight average molecular weight of the photoreactive urethane resin may be 30,000 g / mol or more and 100,000 g / mol or less. Specifically, the weight average molecular weight of the photoreactive urethane-based resin is 35,000 g / mol or more and 90,000 g / mol or less, 45,000 g / mol or more, 70,000 g / mol or less, 35,000 g / mol or more, 75,000 g / mol or less, or 50,000 g / mol or more and 80,000 g / mol or less. By adjusting the weight average molecular weight range of the photoreactive urethane-based resin to the above-described range, an adhesive composition having excellent adhesive properties and an adhesive having improved storage modulus can be prepared.

In addition, the weight average molecular weight of the photoreactive urethane resin may be controlled by adjusting the number average molecular weight of the polyol, or by the relative content ratio between the polyol and the diisocyanate-based compound, and the type of the compound represented by Chemical Formula 1. .

According to an exemplary embodiment of the present invention, the molecular weight distribution of the photoreactive urethane resin may be 1.5 or more and 2.5 or less. The "molecular weight distribution (PDI)" is a value obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn), and the larger the molecular weight distribution, the wider the molecular weight distribution from the low molecular weight to the higher molecular weight, and the smaller the molecular weight distribution is It shows that the molecular weight distribution is narrow from low molecular weight to high molecular weight.

By adjusting the molecular weight distribution of the photoreactive urethane-based resin to the above-described range, reworkability of the pressure-sensitive adhesive containing a cured product of the pressure-sensitive adhesive composition containing the photoreactive urethane-based resin can be improved. In addition, when the molecular weight distribution of the photoreactive urethane resin is within the above range, it is possible to secure the cutability and processability of the pressure-sensitive adhesive containing the cured product of the pressure-sensitive adhesive composition.

According to an exemplary embodiment of the present invention, the glass transition temperature of the photoreactive urethane resin may be -50 ° C or higher and -10 ° C or lower. Specifically, the glass transition temperature of the photoreactive urethane-based resin may be -40 ℃ or more -15 ℃ or less, or -30 ℃ or more -20 ℃ or less. When the glass transition temperature of the photoreactive urethane resin is within the above-described range, an adhesive having an improved storage modulus can be implemented, and the durability of the adhesive can be further improved.

The glass transition temperature of the photoreactive urethane-based resin may be measured using a device and / or method for measuring the glass transition temperature of the resin in the art.

According to an exemplary embodiment of the present invention, the viscosity of the photoreactive urethane resin may be 50,000 cPs or more and 200,000 cPs or less, or 55,000 cPs or more and 195,000 cPs or less. The photoreactive urethane-based resin having the aforementioned viscosity can be more easily mixed with the monomer mixture.

According to an exemplary embodiment of the present invention, the solid content of the photoreactive urethane resin may be 45% or more and 60% or less. By appropriately adjusting the solid content of the photoreactive urethane-based resin as described above, the curing reaction of the pressure-sensitive adhesive composition can be effectively performed.

In the present specification, the “solid content” may mean a solute or a solid substance excluding a solvent in the entire solution. In addition, the content of the solid content may mean weight percent.

According to an exemplary embodiment of the present invention, the second mixture comprising the copolymer and the compound represented by Chemical Formula 1 may further include a catalyst. The content of the catalyst may be 0.0005 parts by weight or more and 0.001 parts by weight or less based on 100 parts by weight of the copolymer.

The catalyst included in the second mixture may be one in which the catalyst used to prepare the copolymer remains. For example, by adding the catalyst to the mixture containing the polyol and the diisocyanate-based compound, the urethane reaction of the polyol and the diisocyanate-based compound can proceed to form the copolymer, and the residual catalyst It may be included in the second mixture comprising the copolymer and the compound represented by the formula (1).

According to an exemplary embodiment of the present invention, by adjusting the content of the catalyst to the above-described range, the reaction rate of the urethane of the polyol and the diisocyanate-based compound, the polymerization reaction rate between the copolymer and the compound represented by Formula 1 It can be effectively promoted. The catalyst may be used without limitation, the catalyst used in the art, for example, a platinum-based catalyst, a tin-based catalyst and an amine-based catalyst.

According to an exemplary embodiment of the present invention, the photoreactive urethane-based resin is a photoreactive end group bonded to a terminal, and is excited by light having a predetermined wavelength value to function as a crosslinking agent. Specifically, when light is irradiated to the pressure-sensitive adhesive composition, radicals are formed on the carbonyl group of the photoreactive end group represented by Chemical Formula 2 of the photoreactive urethane-based resin, so as to act as a crosslinking agent. More specifically, when light is irradiated to the pressure-sensitive adhesive composition, the carbonyl group of the photoreactive end group represented by Chemical Formula 2 is converted into a carbon radical and an oxygen radical, and a crosslinking reaction may proceed by an oxygen radical.

According to an exemplary embodiment of the present invention, the pressure-sensitive adhesive composition includes a photo-crosslinking agent comprising the photoreactive urethane-based resin and the benzophenone group-containing (meth) acrylate compound. The photoreactive end group bound to the end of the photoreactive urethane resin may react with light having a wavelength value of 200 nm or more and 300 nm or less. In addition, the photocrosslinking agent containing the benzophenone group-containing (meth) acrylate compound may be one that reacts to light having a wavelength value of 200 nm or more and 300 nm or less. As will be described later, when light having a wavelength value of 300 nm or more and 400 nm or less is irradiated to the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition may be cured to form a semi-cured product. Thereafter, when light having a wavelength value of 200 nm or more and 300 nm or less is irradiated to the semi-cured product, a photo-crosslinking agent containing the photoreactive urethane-based resin and the benzophenone group-containing (meth) acrylate compound included in the semi-cured product By this, the semi-cured product may be further cured to form a secondary cured product.

According to an exemplary embodiment of the present invention, the benzophenone group-containing (meth) acrylate compound included in the photocrosslinking agent may be a compound represented by the following Chemical Formula 4.

[Formula 4]

In Formula 4, R ¹ may be hydrogen or a methyl group.

According to one embodiment of the present invention, the content of the photoreactive urethane resin may be 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the monomer mixture. Specifically, the content of the photoreactive urethane-based resin is 10 parts by weight or more and 40 parts by weight or less, 15 parts by weight or more, 25 parts by weight or less, 7 parts by weight or more, 20 parts by weight or less, or 25 parts by weight with respect to 100 parts by weight of the monomer mixture It may be more than 50 parts by weight.

According to an exemplary embodiment of the present invention, by adjusting the content of the photoreactive urethane resin to the above-described range, it is possible to improve the adhesion performance of the pressure-sensitive adhesive containing the cured product of the pressure-sensitive adhesive composition. In addition, compatibility between the photoreactive urethane-based resin and (meth) acrylate-based monomers can be effectively improved. Through this, it is possible to effectively reduce the occurrence of cloudiness in the pressure-sensitive adhesive containing a cured product of the pressure-sensitive adhesive composition. Therefore, the pressure-sensitive adhesive containing a cured product of the pressure-sensitive adhesive composition may be suitable for use in a display device.

According to an exemplary embodiment of the present invention, the content of the photocrosslinker may be 1 part by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the photoreactive urethane resin. Specifically, the content of the photocrosslinking agent is 3 parts by weight or more and 13.5 parts by weight or less, 5 parts by weight or more and 12.5 parts by weight or less, 7.5 parts by weight or more and 11.5 parts by weight or less, 1.5 parts by weight or more based on 100 parts by weight of the photoreactive urethane resin It may be 5 parts by weight or less, 5.5 parts by weight or more and 8.5 parts by weight or less, or 10 parts by weight or more and 13 parts by weight or less. By adjusting the content of the photo-crosslinking agent to the above-described range, it is possible to implement an adhesive composition capable of providing an adhesive excellent in reliability for level embedding and optical properties.

According to an exemplary embodiment of the present invention, the content of the alkyl group-containing (meth) acrylate monomer may be 30 parts by weight or more and 80 parts by weight or less with respect to 100 parts by weight of the monomer mixture. Specifically, the content of the alkyl group-containing (meth) acrylate monomer is 40 parts by weight or more and 70 parts by weight or less, 45 parts by weight or more, 60 parts by weight or less, 35 parts by weight or more and 50 parts by weight or less, based on 100 parts by weight of the monomer mixture, Or it may be 55 parts by weight or more and 75 parts by weight or less. By adjusting the content of the alkyl group-containing (meth) acrylate monomer to the above-described range, durability and adhesiveness of the adhesive layer containing the cured product of the adhesive composition can be improved.

In the present specification, “alkyl group” may mean a chain hydrocarbon structure in which an unsaturated bond is not present in the functional group.

According to an exemplary embodiment of the present invention, the alkyl group-containing (meth) acrylate monomer is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl-5- (Meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

According to an exemplary embodiment of the present invention, the content of the cycloalkyl group-containing (meth) acrylate monomer may be 15 parts by weight or more and 55 parts by weight or less with respect to 100 parts by weight of the monomer mixture. Specifically, the content of the cycloalkyl group-containing (meth) acrylate monomer is 20 parts by weight or more and 45 parts by weight or less, 25 parts by weight or more, 35 parts by weight or less, or 40 parts by weight or more and 50 parts by weight with respect to 100 parts by weight of the monomer mixture It may be: By adjusting the content of the cycloalkyl group-containing (meth) acrylate monomer to the above-described range, the adhesive strength of the pressure-sensitive adhesive containing the cured product of the pressure-sensitive adhesive composition can be effectively improved, and the optical properties of the pressure-sensitive adhesive can be suppressed from being reduced. Can be.

According to an exemplary embodiment of the present invention, the cycloalkyl group may include a carbon ring structure in which an unsaturated bond is not present in a functional group, and includes a monocyclic ring or a polycyclic ring having 3 to 20 carbon atoms. can do.

According to an exemplary embodiment of the present invention, the cycloalkyl group-containing (meth) acrylate monomer is cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, 3,3,5-trimethylcyclo Hexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, t-butylcyclohexyl acrylate, and t-butylcyclohexyl methacrylate.

According to an exemplary embodiment of the present invention, the content of the polar group-containing (meth) acrylate monomer may be 5 parts by weight or more and 25 parts by weight or less with respect to 100 parts by weight of the monomer mixture. Specifically, the content of the polar group-containing (meth) acrylate monomer is 7 parts by weight or more and 20 parts by weight or less, 10 parts by weight or more and 15 parts by weight or less, 5.5 parts by weight or more and 7.5 parts by weight or less with respect to 100 parts by weight of the monomer mixture, It may be 9 parts by weight or more and 14 parts by weight or less, or 15 parts by weight or more and 20 parts by weight or less. When the content of the polar group-containing (meth) acrylate monomer is within the above-mentioned range, the pressure-sensitive adhesive containing a cured product of the pressure-sensitive adhesive composition may have improved optical properties and stepped buried properties.

According to an exemplary embodiment of the present invention, the polar functional group-containing monomer may include at least one of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.

According to an exemplary embodiment of the present invention, the hydroxy group-containing monomer is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxy Hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, and 2-hydroxypropylene glycol (meth) acrylate. .

According to an exemplary embodiment of the present invention, the carboxyl group-containing monomer is acrylic acid, methacrylic acid, 2- (meth) acryloyloxy acetic acid, 3- (meth) acryloyloxypropyl acid, 4- (meth) acrylic It may include at least one of monooxy butyric acid, acrylic acid duplex, itaconic acid and maleic acid.

According to an exemplary embodiment of the present invention, the nitrogen-containing monomer is 2-isocyanatoethyl (meth) acrylate, 3-isocyanatopropyl (meth) acrylate, 4-isocyanatobutyl (meth) Acrylate, (meth) acrylamide, N-vinyl pyrrolidone, and N-vinyl caprolactam.

According to an exemplary embodiment of the present invention, the pressure-sensitive adhesive composition may include a photoinitiator that reacts to light having a wavelength value of 300 nm or more and 400 nm or less. As the photoinitiator, a photoinitiator that reacts to light having a wavelength value of 300 nm or more and 400 nm or less can be used without limitation. Specifically, in the present invention, Irgacure-651 (Ciba Co.) may be used as a photoinitiator that reacts to light having a wavelength value of 300 nm or more and 400 nm or less, but the type of photoinitiator is not limited.

According to an exemplary embodiment of the present invention, the content of the photoinitiator may be 0.1 part by weight or more and 1 part by weight or less with respect to 100 parts by weight of the monomer mixture. By adjusting the content of the photoinitiator to the above-described range, it is possible to effectively induce the photocuring reaction of the pressure-sensitive adhesive composition.

According to an exemplary embodiment of the present invention, the pressure-sensitive adhesive composition may further include an additive comprising at least one of a curing agent and an additional crosslinking agent. The content of the additive may be 5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the photoreactive urethane resin. In addition, the content of the additive can be adjusted in a range that does not affect the physical properties of the pressure-sensitive adhesive prepared using the pressure-sensitive adhesive composition.

According to an exemplary embodiment of the present invention, the pressure-sensitive adhesive composition may be a solvent-free type. That is, the pressure-sensitive adhesive composition may not contain a solvent. The solvent-free pressure-sensitive adhesive composition has a low volatile content, through which it is possible to easily implement a durable adhesive.

An exemplary embodiment of the present invention provides an adhesive comprising a cured product of the adhesive composition.

The pressure-sensitive adhesive according to an exemplary embodiment of the present invention has an advantage of excellent optical properties and step fillability. Specifically, the whitening phenomenon of the pressure-sensitive adhesive is suppressed, and thus may have excellent optical properties. In addition, since the pressure-sensitive adhesive contains a cured product formed through a polymerization reaction between a photoreactive urethane-based resin and (meth) acrylate-based monomers, the pressure-sensitive adhesive may have excellent impact resistance and have an improved storage modulus value.

According to an exemplary embodiment of the present invention, the cured product of the pressure-sensitive adhesive composition is an alkyl group-containing (meth) acrylate polymerization unit derived from the alkyl group-containing (meth) acrylate monomer contained in the pressure-sensitive adhesive composition, containing the cyclic substituent ( A cyclic substituent-containing (meth) acrylate polymerization unit derived from a meth) acrylate monomer, a polar group-containing (meth) acrylate polymerization unit derived from the polar group-containing (meth) acrylate monomer, derived from the photoreactive urethane-based resin Polymerization units, and polymerization units derived from the photocrosslinking agent may be included.

According to an exemplary embodiment of the present invention, the cured product included in the pressure-sensitive adhesive may be that the pressure-sensitive adhesive composition is cured by light having a wavelength value of 300 nm or more and 400 nm or less. Specifically, the pressure-sensitive adhesive composition is cured using light having a wavelength value of 300 nm or more and 400 nm or less may be a semi-cured product, and may be formed into a cured product through additional photocuring.

Hereinafter, for convenience of description, the pressure-sensitive adhesive composition is cured by light having a wavelength value of 300 nm or more and 400 nm or less, and is referred to as a semi-cured product.

According to an exemplary embodiment of the present invention, the storage modulus at a temperature of 25 ° C (room temperature) of the pressure-sensitive adhesive containing the semi-cured product may be 100,000 Pa or more and 125,000 Pa or less. Specifically, the storage modulus of the adhesive may be 110,000 Pa or more and 120,000 Pa or less, or 115,000 Pa or more and 118,000 Pa or less. An adhesive having a storage modulus in the above-described range at a temperature of 25 ° C. may have excellent step landfillability.

The storage modulus of the pressure-sensitive adhesive may be measured using an apparatus and / or method for measuring the storage modulus of the pressure-sensitive adhesive in the art. For example, the pressure-sensitive adhesive was prepared as a specimen having a thickness of 600 μm and a diameter of 8 mm in a DISK form, and using TA's ARES-G2, 5 ° C / min at a shear rate of 1 Hz and 1 rad / sec. The storage modulus of the specimen can be measured in a temperature range of -20 ° C to 100 ° C by applying a heating rate. In addition, the measured strain can be set to 10% and the axial force to 2N.

According to an exemplary embodiment of the present invention, the gel content of the pressure-sensitive adhesive containing the semi-cured product may be 65% or more and 70% or less. Specifically, the gel content of the pressure-sensitive adhesive may be 67% or more and 68.5% or less. When the gel content of the pressure-sensitive adhesive containing the semi-cured product is within the above-described range, the initial step landfill property of the pressure-sensitive adhesive containing the semi-cured product may be excellent.

The gel content of the pressure-sensitive adhesive may be measured using a method of measuring the gel content of the pressure-sensitive adhesive in the art. For example, the adhesive is cut to 5 cm × 5 cm (horizontal × vertical) to prepare a specimen, the weight (weight 1) is measured, 50 ml of ethyl acetate solvent is placed in a PET container, and stored at room temperature for 24 hours. . Subsequently, the full-swelled adhesive is filtered through a prepared 140 mm × 140 mm 200 mesh, dried in an oven at 110 ° C. for 2 hours, and then weighed (weight 3). Thereafter, the gel content of the pressure-sensitive adhesive may be measured through Equation 1 below.

[Equation 1]

Gel content (%) = ((Weight 3 -Weight 2) / Weight 1) X 100

In Equation 1, weight 2 is the weight of the mesh.

According to an exemplary embodiment of the present invention, the cured product contained in the pressure-sensitive adhesive composition is a semi-cured material cured by light having a wavelength value of 300 nm or more and 400 nm or less has a wavelength value of 200 nm or more and 300 nm or less. The branches may be further cured by light. That is, the pressure-sensitive adhesive may include a secondary cured product of the pressure-sensitive adhesive composition.

Specifically, when light having a wavelength value of 300 nm or more and 400 nm or less is irradiated to the pressure-sensitive adhesive composition, a curing reaction of the pressure-sensitive adhesive composition may be performed by a photoinitiator included in the pressure-sensitive adhesive composition to form a semi-cured product. Thereafter, when light having a wavelength value of 200 nm or more and 300 nm or less is irradiated to the semi-cured product, a photo-crosslinking agent containing the photoreactive urethane-based resin and the benzophenone group-containing (meth) acrylate compound included in the semi-cured product By this, the semi-cured product may be further cured to form a secondary cured product.

According to an exemplary embodiment of the present invention, the storage modulus at a temperature of 25 ° C (room temperature) of the pressure-sensitive adhesive containing the secondary cured product may be 140,000 Pa or more and 160,000 Pa or less. Specifically, the storage modulus of the adhesive may be 145,000 Pa or more and 150,000 Pa or less, or 145,000 Pa or more and 147,000 Pa or less. Compared to the semi-cured product, as the storage modulus of the secondary cured product is increased, the pressure-sensitive adhesive may have excellent initial level embedding property, and the pressure-sensitive adhesive containing the secondary cured product may have excellent durability and reliability.

According to an exemplary embodiment of the present invention, the gel content of the pressure-sensitive adhesive containing the secondary cured product may be 72.5% or more and 75% or less. That is, the gel content of the secondary cured product may increase compared to the semi-cured product. Specifically, when the value of the gel content of the pressure-sensitive adhesive containing the primary cured product is within the above-mentioned range, the pressure-sensitive adhesive containing the primary cured product may have excellent initial step filling property. Thereafter, as the gel content of the pressure-sensitive adhesive containing the secondary cured product of the primary cured product is increased, the pressure-sensitive adhesive containing the secondary cured product may be improved in durability and reliability.

Hereinafter, examples will be described in detail to specifically describe the present invention. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present invention to those skilled in the art.

Preparation of compound represented by formula (1)

After 700 g of 4-hydroxybenzophenone, 342.49 g of ethylene carbonate, and 15.91 g of sodium iodide were added to the reactor, the temperature of the reactor was raised to 120 ° C. and stirred. As the temperature increased, 4-hydroxybenzophenone and ethylene carbonate were dissolved, and the reaction was performed at 130 ° C for about 8 hours. The yield of the reaction was confirmed by TLC monitoring and 1H-NMR, and after the reaction was completed, the reactor internal temperature was cooled to 50 ° C, and 1 kg of MeOH was added to dilute it. The internal temperature of the reactor was cooled to 5 ° C. to precipitate benzophenone (BPEO) to which ethylene oxide value, a compound represented by Chemical Formula 1, was added. Thereafter, 1 kg of distilled water was additionally added to the precipitated compound to remove the salt formed after the reaction, and the precipitate was recovered using a 300 mesh filter and distilled water was removed. Then, distilled water was added again to the recovered precipitate to remove residual impurities. The above process was repeated 3 times to recover BPEO of high purity, and the BPEO solid was dried in an oven at 55 ° C. through filtering to finally prepare a compound represented by Chemical Formula 1.

Photoreactivity  Preparation of urethane resin

A mixture was prepared by adding 13.88 parts by weight of isophorone diisocyanate (IPDI, Evonik) to the reactor with respect to 100 parts by weight of a polycarbonate diol having a number average molecular weight of about 2,000 g / mol (N963, Tosho). Ethyl hexyl acrylate was added to the reactor as a dilution monomer for about 33 parts by weight of the reactor and stirred, and the temperature of the reactor was raised to 60 ° C. Then, a urethane reaction was initiated by adding 0.0005 parts by weight (0.39 ml) of dibutyltin dilaurate (DBTDL) solution diluted to 10 wt% as a catalyst, and maintained at 60 ° C. for 6 hours, FT-IR It was confirmed that the NCO peak disappeared. Through this, a urethane-based copolymer was prepared.

Thereafter, with respect to 100 parts by weight of the prepared urethane-based copolymer, 6.3 parts by weight of the compound represented by Formula 1 prepared above, and about 72 parts by weight of ethylhexyl acrylate as a diluting monomer were added. Thereafter, the temperature of the reactor was maintained at 70 ° C., and it was confirmed that the NCO peak disappeared by FT-IR. Through this, a syrup was prepared comprising a photoreactive urethane resin and a diluting monomer.

Example  One

Preparation of adhesive composition

A monomer mixture was prepared by mixing 45 parts by weight of ethylhexyl acrylate, 45 parts by weight of isobornyl acrylate, and 10 parts by weight of 2-hydroxyethyl acrylate. Then, about 22.5 parts by weight of the photoreactive urethane resin prepared above was added to 100 parts by weight of the monomer mixture. Thereafter, with respect to 100 parts by weight of the photoreactive urethane-based resin, 4-benzophenone methacrylate as a photocrosslinking agent is about 11 parts by weight, a photoinitiator that reacts to light having a wavelength value of 300 nm or more and 400 nm or less (Irgacure-651, Ciba社) About 0.8 parts by weight, 1,6-hexane diol diacrylate (1,6-Hexanediol diacrylate, HDDA) about 0.2 parts by weight, as an additional crosslinking agent, urethane-based crosslinking agent SUO-1020 about 9.8 parts by weight of the adhesive, The composition was prepared.

Preparation of adhesive

The prepared pressure-sensitive adhesive composition was applied onto a PET base film at 150 μm, and irradiated with UV (wavelength value: 350 nm, light amount: 5 mW, irradiation time: 3 minutes) with a black light ultraviolet lamp (Osram Sylvania), The composition was first cured to prepare an adhesive containing a semi-cured product of the adhesive composition.

Then, using the UV irradiation device (DYMAX, Ltd.) of the metal halide light source for the pressure-sensitive adhesive, irradiating UV containing light having a wavelength value of 200 nm or more and 300 nm or less with energy of 3 J, and curing the secondary adhesive An adhesive comprising a secondary cured product of the composition was prepared.

Comparative example  One

In Example 1, a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that 4-benzophenone methacrylate was not added as a photocrosslinker.

In addition, in the same manner as in Example 1, a pressure-sensitive adhesive containing a semi-cured product of the pressure-sensitive adhesive composition and a pressure-sensitive adhesive including a secondary cured product further cured with a semi-cured product were prepared, respectively.

Through the aforementioned method, the gel content of the pressure-sensitive adhesive containing the primary cured product (semi-cured product) of the pressure-sensitive adhesive composition prepared in Example 1 and Comparative Example 1 and the secondary cured product and the storage modulus at room temperature were described. It measured, and is shown in Table 1 below.

In addition, the reliability of the pressure-sensitive adhesive containing the secondary cured product of the pressure-sensitive adhesive composition prepared in Example 1 and Comparative Example 1 and the level-embedding property were evaluated as follows, and the results are shown in Table 1 below.

First, the pressure-sensitive adhesive containing the primary cured product of the pressure-sensitive adhesive composition prepared in Example 1 and Comparative Example 1 was cut to a size of 7 cm in width and 13 cm in length to prepare an adhesive sample. Thereafter, a pressure-sensitive adhesive sample was rolled on one side of the ITO film, and a glass with a step was rolled on the pressure-sensitive adhesive sample to prepare a specimen. At this time, the glass was used to print eight steps having a height of 50 μm to 70 μm.

Then, the specimen was treated for 20 minutes at a temperature of 40 ° C. in an autoclave and a pressure condition of 4 bar, and secondary curing was performed by irradiating 3J UV. Subsequently, it was placed in a high-temperature and high-humidity chamber with a temperature of 85 ° C and a humidity of 85 RH% and left for 3 days to evaluate the level of landfill and reliability (cloudiness).

The reliability of the adhesive was evaluated as follows. ○ When the area where turbidity occurs is 10% or more and less than 30%, compared to the total area of one surface of the specimen, ○ when the area where turbidity occurs is 30% or more and less than 50%, △, when the area where turbidity occurs is 50% or more It evaluated as X.

In addition, the step landfill property of the adhesive was evaluated as follows. The number of stepped bubbles for each step printed on the glass was visually measured, and the number of stepped bubbles for each printed step was 3, and the number of stepped bubbles was evaluated as X when the number of stepped bubbles was 4 or more.

Gel content (%) Storage modulus (Pa) Step landfill responsibility
(Turbidity) 1st hardening 2nd hardening 1st hardening 2nd hardening Example 1 68.2 74.9 117,812 146,238 ○ ○ Comparative Example 1 65.8 71.9 113,177 135,816 ○ △

Referring to Table 1, it was confirmed that the pressure-sensitive adhesive containing the primary cured product of the pressure-sensitive adhesive composition according to Example 1 has an appropriate gel content and storage modulus, and thus has excellent initial step landfillability. In addition, the pressure-sensitive adhesive comprising a secondary cured product obtained by secondary curing of the primary cured product according to Example 1 increases the gel content and storage modulus as described above, thereby improving reliability (cloudiness) and level embedding. Was confirmed.

On the other hand, the pressure-sensitive adhesive containing the secondary cured product of the pressure-sensitive adhesive composition of Comparative Example 1 was similar to Example 1, it was confirmed that the reliability is inferior.

Therefore, it can be seen that the pressure-sensitive adhesive composition according to an exemplary embodiment of the present invention can realize a pressure-sensitive adhesive having excellent level embedding properties and reliability.

Claims (10)

A copolymer containing a polymerization unit derived from a first mixture containing a polyol and a diisocyanate-based compound; And a photoreactive end group derived from a compound represented by the following Chemical Formula 1 and attached to the terminal of the copolymer;
A photo-crosslinking agent comprising a benzophenone group-containing (meth) acrylate compound; And
A pressure-sensitive adhesive composition comprising; a monomer mixture comprising an alkyl group-containing (meth) acrylate monomer, a cycloalkyl group-containing (meth) acrylate monomer, and a polar group-containing (meth) acrylate monomer;
[Formula 1]

In Chemical Formula 1, n is an integer of 2 to 12.
The method according to claim 1,
The content of the photoreactive urethane resin is 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the monomer mixture.
The method according to claim 1,
The content of the photocrosslinking agent is 1 part by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the photoreactive urethane resin.
The method according to claim 1,
The content of the alkyl group-containing (meth) acrylate monomer is 30 parts by weight or more and 80 parts by weight or less with respect to 100 parts by weight of the monomer mixture.
The method according to claim 1,
The content of the cycloalkyl group-containing (meth) acrylate monomer is 15 parts by weight or more and 55 parts by weight or less with respect to 100 parts by weight of the monomer mixture.
The method according to claim 1,
The content of the polar group-containing (meth) acrylate monomer is 5 parts by weight or more and 25 parts by weight or less with respect to 100 parts by weight of the monomer mixture.
The method according to claim 1,
An adhesive composition further comprising a photoinitiator that reacts to light having a wavelength value of 300 nm or more and 400 nm or less.
An adhesive comprising a cured product of the adhesive composition according to claim 1.
The method according to claim 8,
The cured product is an adhesive in which the adhesive composition is cured by light having a wavelength value of 300 nm or more and 400 nm or less.
The method according to claim 8,
The cured product is an adhesive in which the pressure-sensitive adhesive composition is cured by light having a wavelength value of 300 nm or more and 400 nm or less, and the cured product is further cured by light having a wavelength value of 200 nm or more and 300 nm or less.