阅读说明：本技术 多层粘合带 (Multi-layer adhesive tape ) 是由 洪在成 林东勋 徐周用 崔埈满 金雨渊 宋镐径 金章淳 斯莱·李 徐光洙 于 2018-05-18 设计创作，主要内容包括：提供了具有优异的台阶覆盖和可再处理性的多层粘合带。所述多层粘合带顺序地包括：第一外粘合剂层；中间粘合剂层；和第二外粘合剂层,其中所述中间粘合剂层包含中间粘合剂聚合物,所述中间粘合剂聚合物包含：含烷基的(甲基)丙烯酸酯单体的聚合单元；含羧基的单体的聚合单元；和基于丙烯酰胺的单体的聚合单元。(A multi-layer adhesive tape having excellent step coverage and recyclability is provided. The multi-layered adhesive tape sequentially comprises: a first outer adhesive layer; an intermediate adhesive layer; and a second outer adhesive layer, wherein the intermediate adhesive layer comprises an intermediate adhesive polymer comprising: polymerized units of an alkyl-containing (meth) acrylate monomer; polymerized units of a carboxyl-containing monomer; and polymerized units of acrylamide-based monomers.)

1. A multi-layer adhesive tape comprising, in order:

A first outer adhesive layer;

An intermediate adhesive layer; and

A second outer layer of an adhesive comprising a second adhesive layer,

Wherein the intermediate adhesive layer comprises an intermediate adhesive polymer comprising: polymerized units of an alkyl-containing (meth) acrylate monomer; polymerized units of a carboxyl-containing monomer; and polymerized units of acrylamide-based monomers.

2. The multi-layered adhesive tape as claimed in claim 1, wherein the content of the polymerized units of the carboxyl group-containing monomer is 1 part by weight or more and 15 parts by weight or less based on 100 parts by weight of the intermediate adhesive polymer.

3. The multi-layered adhesive tape as claimed in claim 1, wherein the content of the polymerized units of the acrylamide-based monomer is 1 part by weight or more and 15 parts by weight or less based on 100 parts by weight of the intermediate adhesive polymer.

4. The multi-layered adhesive tape according to claim 1, wherein the weight ratio of the polymerized units of the carboxyl group-containing monomer to the polymerized units of the (meth) acrylamide-based monomer is 1:0.1 to 1: 1.8.

5. The multi-layer adhesive tape of claim 1, wherein the first outer adhesive layer and the second outer adhesive layer each comprise an outer adhesive polymer comprising: polymerized units of an alkyl-containing (meth) acrylate monomer; and polymerized units of a crosslinkable monomer.

6. The multi-layered adhesive tape of claim 5, wherein the content of the polymerized unit of the crosslinkable monomer is 1 part by weight or more and 30 parts by weight or less based on 100 parts by weight of the outer adhesive polymer.

7. The multi-layered adhesive tape of claim 1, wherein the thickness of the intermediate adhesive layer is 30 μ ι η or more and 100 μ ι η or less.

8. The multi-layer adhesive tape of claim 1, wherein the thickness of each of the first outer adhesive layer and the second outer adhesive layer is 25 μ ι η or more and 60 μ ι η or less.

9. The multi-layer adhesive tape of claim 1, wherein the thickness ratio of the first outer adhesive layer to the middle adhesive layer and the thickness ratio of the second outer adhesive layer to the middle adhesive layer are each 1:0.5 to 1: 2.

10. The multi-layer adhesive tape of claim 1, further comprising:

a first interfacial mixture layer disposed between the first outer adhesive layer and the middle adhesive layer; and

A second interfacial mixture layer disposed between the second outer adhesive layer and the intermediate adhesive layer.

Technical Field

A multi-layer adhesive tape is provided.

Background

The various components are attached to the electronic device by adhesives. For example, various optical members such as a polarizing plate, a phase difference plate, an optical compensation film, a reflective sheet, a protective film, and a brightness enhancement film may be attached to a Liquid Crystal Display (LCD) by an adhesive tape. Recently, as the performance of apparatuses using adhesive tapes improves, physical properties required for the adhesive tapes are gradually diversified. As an example, an adhesive tape that minimizes white turbidity and is excellent in recyclability (in which there is no residual residue when the adhesive tape is removed for reconstruction) is required, and research on the tape is required.

[ documents of the related art ]

[ patent document ]

Korean patent application laid-open No. KR 10-2016-0025050A

Disclosure of Invention

Technical problem

Provided is a multi-layered adhesive tape having excellent step coverage and reworkability.

Technical scheme

One exemplary embodiment provides a multi-layered adhesive tape, sequentially comprising: a first outer adhesive layer; an intermediate adhesive layer; and a second outer adhesive layer, wherein the intermediate adhesive layer comprises an intermediate adhesive polymer comprising: polymerized units of an alkyl-containing (meth) acrylate monomer; polymerized units of a carboxyl-containing monomer; and polymerized units of acrylamide-based monomers.

Advantageous effects

The multi-layered adhesive tape according to one exemplary embodiment minimizes white turbidity and thus has high transparency.

The multi-layered adhesive tape according to one exemplary embodiment is easily removed during reconstruction due to excellent recyclability.

The multi-layered adhesive tape according to one exemplary embodiment has excellent step coverage.

Drawings

Fig. 1 is a schematic view of a laminated structure of a multi-layered adhesive tape according to an exemplary embodiment.

Fig. 2 is a schematic view of a laminated structure of a multi-layered adhesive tape according to an exemplary embodiment.

Detailed Description

In this specification, when one member is provided "on" another member, this includes not only a case where one member is in contact with another member but also a case where another member is present between the two members.

In the present specification, when a portion "includes" one constituent element, unless specifically described otherwise, this does not mean that another constituent element is excluded, but means that another constituent element may be further included.

In the present specification, the term "polymerized unit of a monomer" means a form in which the monomer forms a backbone (e.g., a main chain or a side chain) of a polymer by performing a polymerization reaction.

In the present specification, the unit "parts by weight" means a weight ratio between the components.

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

One exemplary embodiment provides a multi-layered adhesive tape, sequentially comprising: a first outer adhesive layer; an intermediate adhesive layer; and a second outer adhesive layer, wherein the intermediate adhesive layer comprises an intermediate adhesive polymer comprising: polymerized units of an alkyl-containing (meth) acrylate monomer; polymerized units of a carboxyl-containing monomer; and polymerized units of acrylamide-based monomers.

Fig. 1 is a schematic view of a laminated structure of a multi-layered adhesive tape according to an exemplary embodiment. Specifically, fig. 1 shows a multi-layered adhesive tape in which a first outer adhesive layer 101, an intermediate adhesive layer 201, and a second outer adhesive layer 102 are sequentially laminated.

According to an exemplary embodiment of the present invention, the multi-layered adhesive tape has excellent recyclability and simultaneously can minimize white turbidity because the intermediate adhesive layer includes an intermediate adhesive polymer containing both polymerized units of a carboxyl group-containing monomer and polymerized units of an acrylamide-based monomer. In particular, the intermediate adhesive layer of the multi-layer adhesive tape may have a higher tensile strength than the first and second outer adhesive layers. Further, when the multi-layer adhesive tape is attached to an adherend and then separated due to a change in need, the multi-layer adhesive tape is not easily broken due to the intermediate adhesive layer. Therefore, the multi-layer adhesive tape has an advantage in that the multi-layer adhesive tape can be easily separated from an adherend.

In addition, the first and second outer adhesive layers of the multi-layer adhesive tape may have a low glass transition temperature. Therefore, the multi-layered adhesive tape can have excellent step coverage.

According to an exemplary embodiment of the present invention, the content of the polymerized units of the alkyl group-containing (meth) acrylate monomer may be 30 parts by weight or more and 90 parts by weight or less, 50 parts by weight or more and 85 parts by weight or less, 60 parts by weight or more and 80 parts by weight or less, or 70 parts by weight or more and 80 parts by weight or less, based on 100 parts by weight of the intermediate adhesive polymer.

According to an exemplary embodiment of the present invention, the carboxyl group-containing monomer may be one or more selected from the group consisting of: acrylic acid, methacrylic acid, 2-carboxyethylacrylic acid, 3-carboxypropylacrylic acid, 2- (meth) acryloxyacetic acid, 3- (meth) acryloxypropionic acid, 4- (meth) acryloxybutyric acid, acrylic acid dimer, itaconic acid, and maleic acid.

According to an exemplary embodiment of the present invention, the content of the polymerized unit of the carboxyl group-containing monomer may be 1 part by weight or more and 15 parts by weight or less. Specifically, according to an exemplary embodiment of the present invention, the content of the polymerized unit of the carboxyl group-containing monomer may be 2 parts by weight or more and 10 parts by weight or less, or 1 part by weight or more and 5 parts by weight or less, based on 100 parts by weight of the intermediate binder polymer. When the content of the polymerized unit of the carboxyl group-containing monomer is within the above range, the content may be adjusted to a range in which the cohesive force of the intermediate adhesive layer does not excessively increase and the heat resistance of the intermediate adhesive layer may be ensured. Further, in the above range, generation of step bubbles of the multi-layer adhesive tape caused by the lifting in the vicinity of the step can be minimized.

According to an exemplary embodiment of the present invention, the acrylamide-based monomer may be one or more selected from the group consisting of: acrylamide, N-diphenyl (meth) acrylamide, N- (N-dodecyl) (meth) acrylamide, N-dimethyl (meth) acrylamide, N-hydroxyethyl acrylamide, N-alkyl (meth) acrylamide, N-dialkyl (meth) acrylamide, dimethylacrylamide, and N, N-diaryl (meth) acrylamide.

According to an exemplary embodiment of the present invention, the content of the polymerized unit of the acrylamide-based monomer may be 1 part by weight or more and 15 parts by weight or less. Specifically, the content of the polymerized unit of the acrylamide-based monomer may be 3 parts by weight or more and 12 parts by weight or less, based on 100 parts by weight of the intermediate adhesive polymer. When the content of the polymerized unit of the acrylamide-based monomer is within the above range, white turbidity of the intermediate adhesive layer may be minimized, and at the same time, the recyclability and step coverage of the multi-layered adhesive tape may be improved.

according to an exemplary embodiment of the present invention, the total content of the polymerized units of the carboxyl group-containing monomer and the polymerized units of the (meth) acrylamide-based monomer in the intermediate binder polymer may be 5 parts by weight or more and 30 parts by weight or less. Specifically, the total content of the polymerized units of the carboxyl group-containing monomer and the polymerized units of the (meth) acrylamide-based monomer in the intermediate binder polymer may be 10 parts by weight or more and 25 parts by weight or less, or 10 parts by weight or more and 15 parts by weight or less, based on 100 parts by weight of the intermediate binder polymer. When the total content of the polymerized units of the carboxyl group-containing monomer and the polymerized units of the (meth) acrylamide-based monomer is within the above range, the intermediate adhesive layer can sufficiently suppress white turbidity, and in addition, can also contribute to improvement of step coverage and recyclability of the multi-layered adhesive tape.

According to an exemplary embodiment of the present invention, the weight ratio of the polymerized units of the carboxyl group-containing monomer to the polymerized units of the (meth) acrylamide-based monomer may be 1:0.1 to 1: 1.8. Specifically, according to an exemplary embodiment of the present invention, the weight ratio of the polymerized unit of the carboxyl group-containing monomer to the polymerized unit of the (meth) acrylamide-based monomer may be 1:0.2 to 1: 1.5. When the weight ratio of the polymerized units of the carboxyl group-containing monomer to the polymerized units of the (meth) acrylamide-based monomer is within the above range, the intermediate adhesive layer may have a function of suppressing white turbidity and may have appropriate strength. Therefore, step coverage of the multi-layer adhesive tape can also be ensured.

According to an exemplary embodiment of the present invention, the intermediate adhesive polymer may further include polymerized units of a cycloalkyl-containing (meth) acrylate monomer.

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

According to an exemplary embodiment of the present invention, the cycloalkyl-containing (meth) acrylate monomer may be one or more selected from the group consisting of: cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), isobornyl acrylate (IBOA), isobornyl methacrylate (IBOMA), isobornyl (meth) acrylate, and 3,3, 5-trimethylcyclohexyl acrylate (TMCHA), but are not limited thereto.

According to an exemplary embodiment of the present invention, the content of the polymerized units of the cycloalkyl group-containing (meth) acrylate monomer may be more than 0 part by weight and 30 parts by weight or less, or 5 parts by weight or more and 15 parts by weight or less, based on 100 parts by weight of the intermediate adhesive polymer. In the intermediate adhesive layer, when the content of the polymerized unit of the cycloalkyl group-containing (meth) acrylate monomer is within the above range, the multi-layered adhesive tape may have both appropriate adhesion and high step coverage. Further, within the content range, the recyclability of the multi-layer adhesive tape can be improved. Specifically, within the content range, the strength of the multi-layer adhesive tape can be appropriately maintained, and therefore, when reconstruction is required, the multi-layer adhesive tape can be easily removed from an adherend. Further, within the content range, the intermediate adhesive composition may be easily applied and cured, and generation of delayed bubbles in the intermediate adhesive layer may be minimized.

According to an exemplary embodiment of the present invention, the first and second outer adhesive layers may each comprise an outer adhesive polymer comprising: polymerized units of an alkyl-containing (meth) acrylate monomer; and polymerized units of a crosslinkable monomer.

According to an exemplary embodiment of the present invention, the first outer adhesive layer and the second outer adhesive layer may be formed of the same composition. Further, the thicknesses of the first and second outer adhesive layers may be the same as each other.

According to an exemplary embodiment of the present invention, the content of the polymerized unit of the alkyl group-containing (meth) acrylate monomer in the first and second outer adhesive layers may be 30 parts by weight or more and 95 parts by weight or less, or 50 parts by weight or more and 90 parts by weight or less, based on 100 parts by weight of the outer adhesive polymer.

According to an exemplary embodiment of the present invention, the content of the polymerized unit of the crosslinkable monomer may be 1 part by weight or more and 30 parts by weight or less based on 100 parts by weight of the outer binder polymer. When the content of the polymerized unit of the crosslinkable monomer is within the above range, the multi-layered adhesive tape may have improved recyclability, and in addition, may also have durability against high temperature and high humidity, because the cohesive force of the outer adhesive layer may be appropriately maintained.

According to an exemplary embodiment of the present invention, the alkyl group-containing (meth) acrylate monomer may be a (meth) acrylate having an alkyl group having 1 to 20 carbon atoms. Specifically, the alkyl group-containing (meth) acrylate monomer may be one or more selected from the group consisting of: 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-ethylhexyl (meth) acrylate, 2-methylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, and isooctyl (meth) acrylate.

According to an exemplary embodiment of the present invention, the crosslinkable monomer is a monomer having a crosslinkable functional group and other functional groups capable of forming the binder polymer, and may mean a monomer capable of providing the crosslinkable functional group to the binder polymer.

According to an exemplary embodiment of the present invention, the crosslinkable monomer may include one or more selected from the group consisting of: hydroxyl group-containing monomers, carboxyl group-containing monomers, and nitrogen-containing monomers. Specifically, the crosslinkable monomer may include both a hydroxyl group-containing monomer and a carboxyl group-containing monomer.

According to an exemplary embodiment of the present invention, the hydroxyl group-containing monomer may be one or more selected from the group consisting of: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, and 2-hydroxypropanediol (meth) acrylate.

according to an exemplary embodiment of the present invention, the carboxyl group-containing monomer may be one or more selected from the group consisting of: acrylic acid, methacrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropionic acid, 4- (meth) acryloyloxybutyric acid, acrylic acid dimer, itaconic acid, and maleic acid, but are not limited thereto.

According to an exemplary embodiment of the present invention, the nitrogen-containing monomer may be one or more selected from the group consisting of: 2-isocyanatoethyl (meth) acrylate, 3-isocyanatopropyl (meth) acrylate, 4-isocyanatobutyl (meth) acrylate, (meth) acrylamide, N-vinylpyrrolidone, dimethylacrylamide, and N-vinylcaprolactam, but are not limited thereto.

According to an exemplary embodiment of the present invention, the outer adhesive polymer may further include polymerized units of a heterocycloalkyl-containing (meth) acrylate monomer.

According to an exemplary embodiment of the present invention, the heterocycloalkyl group may include a ring structure in which an unsaturated bond is not present in the functional group and a heteroatom other than carbon is included. In addition, the heterocycloalkyl group may include a structure in which one or more carbon atoms are substituted with a heteroatom in a monocyclic or polycyclic structure having 3 to 20 carbon atoms.

According to an exemplary embodiment of the present invention, the heterocycloalkyl-containing (meth) acrylate monomer may be one or more selected from the group consisting of: tetrahydrofurfuryl acrylate (THFA), tetrahydrofurfuryl methacrylate, tetrahydropyranyl acrylate (THPA), acryloylmorpholine, and cyclotrimethylol-propane formal acrylate (CTFA).

According to an exemplary embodiment of the present invention, the content of the polymerized unit of the heterocycloalkyl-containing (meth) acrylate monomer may be 1 part by weight or more and 15 parts by weight or less. Specifically, according to an exemplary embodiment of the present invention, the content of the polymerized unit of the heterocycloalkyl-containing (meth) acrylate monomer may be 5 parts by weight or more and 15 parts by weight or less based on 100 parts by weight of the external adhesive polymer.

According to an exemplary embodiment of the present invention, the intermediate adhesive polymer may be formed by solution-polymerizing a composition including an alkyl group-containing (meth) acrylate monomer, a carboxyl group-containing monomer, and an acrylamide-based monomer. Specifically, the intermediate binder polymer may be formed by polymerizing monomers through thermal polymerization and/or photopolymerization of the composition.

Further, according to an exemplary embodiment of the present invention, each of the first and second outer adhesive polymers may be formed by solution-polymerizing a composition including an alkyl group-containing (meth) acrylate monomer and a polar functional group-containing monomer. Specifically, the first and second outer binder polymers may be formed by polymerizing monomers through thermal polymerization and/or photo-polymerization of the monomers.

According to an exemplary embodiment of the present invention, each of the intermediate adhesive polymer, the first outer adhesive polymer, and the second outer adhesive polymer may further include other materials commonly used in the art such as a crosslinking agent, an initiator, and a tackifier, if necessary.

In the present specification, the glass transition temperature (Tg) is measured by raising the temperature using a Differential Scanning Calorimeter (DSC) (Q-1000, TA Instrument) at a heating rate of 5 ℃/min in a temperature range of-70 ℃ to 100 ℃. In this case, the glass transition temperature is determined as the midpoint of the DSC curve.

According to an exemplary embodiment of the present invention, the glass transition temperature of the intermediate adhesive layer may be-40 ℃ or more and 0 ℃ or less, specifically, -40 ℃ or more and-15 ℃ or less, and more specifically, -40 ℃ or more and-20 ℃ or less, or-35 ℃ or more and-25 ℃ or less. When the glass transition temperature of the intermediate adhesive layer is within the above range, the stampability of the multi-layer adhesive tape may be improved, the multi-layer adhesive tape may be easily handled, and the multi-layer adhesive tape may have more improved step coverage.

According to an exemplary embodiment of the present invention, the glass transition temperature of each of the first and second outer adhesive layers may be-60 ℃ or more and-20 ℃ or less, specifically, -60 ℃ or more and-30 ℃ or less, and more specifically, -60 ℃ or more and-40 ℃ or less, or-55 ℃ or more and-45 ℃ or less.

When the glass transition temperature of each of the first and second outer adhesive layers is within the above range, the multi-layered adhesive tape may achieve excellent step coverage and may minimize deterioration of stampability.

According to an exemplary embodiment of the present invention, the glass transition temperature of the intermediate adhesive layer may be higher than the glass transition temperatures of the first and second outer adhesive layers. Accordingly, the intermediate adhesive layer may have a higher stretching force than each of the first and second outer adhesive layers. Since the intermediate adhesive layer has a relatively high glass transition temperature and stretching force, the multi-layer adhesive tape does not completely break when the multi-layer adhesive tape is attached to an adherend and then removed for reconstruction. Therefore, the multilayer adhesive tape can be easily removed from the adherend. In particular, the intermediate adhesive layer may be used to improve the recyclability of the multi-layer adhesive tape.

In addition, the first and second outer adhesive layers have a low glass transition temperature, and thus high step coverage can be achieved. In particular, the first and second outer adhesive layers may achieve high fluidity due to a low glass transition temperature, and thus, the multi-layered adhesive tape may be effectively embedded in the step portion.

The multi-layered adhesive tape can achieve both high step coverage and excellent recyclability by including a plurality of adhesive layers having different physical properties. In particular, when the difference between the glass transition temperatures of each of the first and second outer adhesive layers and the intermediate adhesive layer is 5 ℃ or more and 25 ℃ or less, the multi-layered adhesive tape may exhibit optimal performance.

According to an exemplary embodiment of the present invention, the thickness of the intermediate adhesive layer may be 30 μm or more and 100 μm or less, 30 μm or more and 80 μm or less, 40 μm or more and 70 μm or less, or 45 μm or more and 65 μm or less. When the thickness of the intermediate adhesive layer is within the above range, the multi-layered adhesive tape may have improved step coverage and may effectively suppress white turbidity.

According to an exemplary embodiment of the present invention, the thickness of each of the first and second outer adhesive layers may be 25 μm or more and 60 μm or less, 25 μm or more and 55 μm or less, 30 μm or more and 60 μm or less, 40 μm or more and 50 μm or less, or 45 μm or more and 55 μm or less. When the thicknesses of the first and second outer adhesive layers are within the above ranges, the multi-layered adhesive tape may have excellent step coverage and long-term durability. Further, when the thicknesses of the first and second outer adhesive layers are outside the above ranges, the recyclability may be deteriorated, and the low cohesive force may cause a decrease in long-term durability.

According to an exemplary embodiment of the present invention, the total thickness of the multi-layered adhesive tape may be 100 μm or more and 250 μm or less. Specifically, the total thickness of the multi-layered adhesive tape may be 100 μm or more and 200 μm or less, or 120 μm or more and 170 μm or less. When the total thickness of the multi-layered adhesive tape is within the above range, the multi-layered adhesive tape may have high adhesiveness, step absorbability, and recyclability at the same time although the thickness is small.

According to an exemplary embodiment of the present invention, the first and second outer adhesive layers may be formed by using compositions having the same composition. Further, the thicknesses of the first and second outer adhesive layers may be the same as each other.

According to an exemplary embodiment of the present invention, the thickness ratio of the first outer adhesive layer to the middle adhesive layer and the thickness ratio of the second outer adhesive layer to the middle adhesive layer may each be 1:0.5 to 1:2, 1:0.7 to 1:2, or 1:0.7 to 1: 1.5. When the thickness ratio of the intermediate adhesive layer to each of the first and second outer adhesive layers is within the above range, the multi-layered adhesive tape has both excellent step coverage and excellent recyclability. Further, when the thickness ratio of the first outer adhesive layer or the second outer adhesive layer to the intermediate adhesive layer is out of the above range, resulting in an increase in the fraction of the outer adhesive layer in thickness, punchability and recyclability at the time of handling may be deteriorated due to a too high thickness fraction of the relatively flexible outer adhesive layer. When the thickness ratio of the first outer adhesive layer or the second outer adhesive layer to the intermediate adhesive layer is out of the above range, resulting in an increase in the fraction of the intermediate adhesive layer in thickness, step coverage may be deteriorated due to a too high thickness fraction of the relatively hard intermediate adhesive layer.

When the thickness of the intermediate adhesive layer is within the above range and the above thickness ratio of the intermediate adhesive layer to each of the first outer adhesive layer and the second outer adhesive layer is maintained, the multi-layered adhesive tape may have both excellent step coverage and excellent recyclability.

According to an exemplary embodiment of the present invention, the multi-layered adhesive tape may further include: a first interfacial mixture layer disposed between the first outer adhesive layer and the middle adhesive layer; and a second interfacial mixture layer disposed between the second outer adhesive layer and the intermediate adhesive layer. In particular, the first interfacial mixture layer may comprise both the material constituting the first outer adhesive layer and the material constituting the intermediate adhesive layer. Further, the second interfacial mixture layer may comprise both the material constituting the second outer adhesive layer and the material constituting the intermediate adhesive layer.

Fig. 2 is a schematic view of a laminated structure of a multi-layered adhesive tape according to an exemplary embodiment. Specifically, fig. 2 shows a laminated structure of a multilayer adhesive tape in which a first interfacial mixture layer 301 is provided between a first outer adhesive layer 101 and an intermediate adhesive layer 201, and a second interfacial mixture layer 302 is provided between the intermediate adhesive layer 201 and a second outer adhesive layer 102.

According to an exemplary embodiment of the present invention, a multi-layered adhesive tape may be prepared by: the first outer adhesive composition, the intermediate adhesive composition, and the outer adhesive composition are sequentially laminated, and then the compositions are simultaneously cured (specifically, photocured). The first outer adhesive composition may constitute the first outer adhesive layer after curing, the intermediate adhesive composition may constitute the intermediate adhesive layer after curing, and the second outer adhesive composition may constitute the second outer adhesive layer after curing. Specifically, the multi-layered adhesive tape may be prepared by a method including laminating a liquid-phase adhesive composition and then simultaneously curing the adhesive composition, rather than a method including separately preparing respective layers and then bonding the layers. Accordingly, a liquid mixing region may be formed between the respective layers in the multi-layer adhesive tape. The multi-layered adhesive tape can ensure superior interlayer adhesion due to a liquid mixing interval as compared to a general multi-layered adhesive tape, and can prevent an interfacial separation phenomenon between layers in an extremely low temperature environment.

According to an exemplary embodiment of the present invention, an interface layer resulting from liquid mixing may be present at each of an interface between the first outer adhesive composition and the intermediate adhesive composition and an interface between the intermediate adhesive composition and the outer adhesive composition. Specifically, the interface layer resulting from liquid mixing at the interface between the first outer adhesive composition and the intermediate adhesive composition may constitute the first interface mixture layer. Further, an interface layer resulting from liquid mixing at the interface between the intermediate adhesive composition and the second outer adhesive composition may constitute the second interface mixture layer.

According to an exemplary embodiment of the present invention, the first outer adhesive composition, the intermediate adhesive composition, and the second outer adhesive composition may be sequentially applied to the substrate. Further, the first outer adhesive composition, the intermediate adhesive composition, and the second outer adhesive composition may be applied to the substrate simultaneously. As a method of applying the adhesive composition, a method generally used in the art such as a slit die and a lip die (lip die) may be used.

According to an exemplary embodiment of the present invention, the thickness of the intermediate adhesive layer may be the shortest distance from the center of the first interfacial mixture layer to the center of the second interfacial mixture layer. Further, the thickness of the first outer adhesive layer may be a shortest distance from the center of the first interfacial mixture layer to the outer side surface of the first outer adhesive layer. Further, the thickness of the second outer adhesive layer may be a shortest distance from the center of the second interfacial mixture layer to an outer side surface of the second outer adhesive layer.

According to an exemplary embodiment of the present invention, the multi-layered adhesive tape may be prepared by curing each of the intermediate adhesive composition and the outer adhesive composition in the form of a film, and then combining the films. Specifically, the multi-layer adhesive tape may be prepared by: the first outer adhesive layer, the intermediate adhesive layer, and the second outer adhesive layer are separately prepared in the form of films, the films are sequentially laminated, and then the resultant laminate is pressed. However, the preparation method of the multi-layered adhesive tape is not limited to the preparation method, and the multi-layered adhesive tape may be prepared by using a preparation method generally applied in the art.

The multi-layered adhesive tape may be used to attach various optical members such as a polarizing plate, a phase difference plate, an optical compensation film, a reflective sheet, a protective film, and a brightness enhancement film. However, the use of the multi-layered adhesive tape is not limited thereto, and the multi-layered adhesive tape may be used without limitation for uses that can be used in the art.

Modes for carrying out the invention

Hereinafter, the present invention will be described in detail with reference to examples for specifically describing the present invention. However, the embodiment according to the present invention may be modified into various forms, and it should not be construed that the scope of the present invention is limited to the following embodiments. The embodiments of the present description are provided to more fully explain the present invention to those of ordinary skill in the art.

[ examples, comparative examples and reference examples ]

Intermediate adhesive compositions according to examples 1 and 2, comparative examples 1 to 5 and reference example 1 were prepared as in table 1 below.

In addition, an external adhesive composition comprising 88 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of tetrahydrofurfuryl methacrylate, and 2 parts by weight of acrylic acid was prepared based on 100 parts by weight of the composition.

The outer adhesive composition, the intermediate adhesive composition, and the outer adhesive composition were sequentially applied to thicknesses of 45 μm, 60 μm, and 45 μm, respectively, and then simultaneously UV-cured, thereby preparing a multi-layered adhesive tape sequentially including a first outer adhesive layer, an intermediate adhesive layer, and a second outer adhesive layer.

[ Table 1]

EHA: 2-ethylhexyl acrylate

IBOMA: isobornyl methacrylate

AA: acrylic acid

HBA: acrylic acid hydroxy butyl ester

DMAA: dimethylacrylamide

[ Experimental example 1]

The evaluation results of the physical properties of the multi-layered adhesive tapes prepared according to examples 1 and 2, comparative examples 1 to 5, and reference example 1 are shown in table 2 below.

[ Table 2]

	White turbidity	Step coverage	Recyclability
				Example 1	○	○	◎
EXAMPLE 2	○	◎	○
				Comparative example 1	X	○	△
Comparative example 2	X	○	○
				Comparative example 3	○	△	△
Comparative example 4	○	X	○
				Comparative example 5	△	○	○
Reference example 1	◎	X	◎

Evaluation of white turbidity

The prepared multi-layered adhesive tape was attached to a glass substrate having a thickness of 1.1T, and a glass substrate having a thickness of 0.55T was laminated on the multi-layered adhesive tape, which was then left to stand in an autoclave at 40 ℃ and 4 bar for 20 minutes. Next, a light source emitting metal halide light having an energy of 3J was placed adjacent to the glass substrate having a thickness of 0.55T, and then the glass substrate was exposed. Next, after allowing the glass substrate to stand at 80 ℃ and 95 RH% for 3 days and at room temperature for 30 minutes, the white turbidity was evaluated by examining the area where the white turbidity occurred in the entire area of the multi-layer adhesive tape. Specifically, a case where the area where white turbidity occurred in the entire area of the multilayer adhesive tape was less than 10%, a case where the area where white turbidity occurred in the entire area of the multilayer adhesive tape was 10% or more and less than 30%, a case where the area where white turbidity occurred in the entire area of the multilayer adhesive tape was 30% or more and less than 50%, and a case where the area where white turbidity occurred in the entire area of the multilayer adhesive tape was 50% or more were evaluated as ". circleigh.", ". smalt.," Δ ", and" x ", respectively.

Evaluation of step coverage

The prepared multi-layered adhesive tape was attached to a glass substrate having a frame portion with a printing step of 20 μm and a screen portion without a printing step, and a glass substrate having a thickness of 0.55T was laminated thereon. Further, after the resultant laminate was left to stand in an autoclave at 40 ℃ and 4 bar for 20 minutes, the step coverage was evaluated by determining the number of bubbles generated due to failure to sufficiently overcome the steps at the four apex portions of the frame portion and the number of delayed bubbles at the wire mesh portion after the lapse of 24 hours. Specifically, the case where the number of delay bubbles was 2 or less and no delay bubbles appeared, the case where the number of delay bubbles was 2 to 3 and delay bubbles were slightly generated, the case where the number of delay bubbles was 3 to 4 and delay bubbles were significantly generated, and the case where the number of delay bubbles was 4 or more and delay bubbles were significantly generated were evaluated as "excellent", "o", "Δ", and "x", respectively.

Evaluation of recyclability

When the prepared multi-layered adhesive tape was attached to a glass substrate, the substrate was allowed to stand in an autoclave at 40 ℃ and 4 bar for 20 minutes, and then the multi-layered adhesive tape was removed, and the multi-layered adhesive tape was completely removed without breaking, the multi-layered adhesive tape was broken but the removal work required 5 or less times, the multi-layered adhesive was easily broken so that the removal work required 6 or more times, and the multi-layered adhesive was easily broken and the removal work was impossible were evaluated as ". circleincircle", ". smallcircle", ". DELTA", and "×", respectively.

From table 2, it can be seen that white turbidity was effectively prevented in the case of examples 1 and 2 having an intermediate adhesive layer prepared from an adhesive composition containing both a carboxyl group-containing monomer and an acrylamide-based monomer, as compared to comparative examples 1 and 2 prepared from an adhesive composition containing only a carboxyl group-containing monomer and not an acrylamide-based monomer. Also, it can be seen that in the case of examples 1 and 2, white turbidity was effectively prevented, compared to comparative example 5, which was prepared from an adhesive composition containing only an acrylamide-based monomer without a carboxyl group-containing monomer. Further, it can be seen that step coverage and/or recyclability are low in the case of comparative examples 3 and 4 having an intermediate adhesive layer prepared from an adhesive composition comprising a carboxyl group-containing monomer and a hydroxyl group-containing monomer, as compared to examples 1 and 2.

Further, it can be confirmed that reference example 1 was prepared from an adhesive composition containing both a carboxyl group-containing monomer and an acrylamide-based monomer, but the content of the acrylamide-based monomer was very high, and thus, the step coverage was low.

[ reference example 2]

A multi-layered adhesive tape was prepared in the same manner as in example 1, except that the thickness of the intermediate adhesive layer was adjusted to 30 μm, and the thickness of each of the first and second outer adhesive layers was adjusted to 60 μm.

[ reference example 3]

A multi-layered adhesive tape was prepared in the same manner as in example 1, except that the thickness of the intermediate adhesive layer was adjusted to 100 μm, and the thickness of each of the first and second outer adhesive layers was adjusted to 25 μm.

[ Experimental example 2]

The physical property evaluation results and the thicknesses of the respective layers of the multi-layered adhesive tape prepared in example 1 and reference examples 2 and 3 in the same manner as in experimental example 1 are shown in table 3 below.

[ Table 3]

From table 3, it can be seen that in reference example 2, the thickness of the intermediate layer was very small compared to the thickness of the outer adhesive layer, and therefore, the recyclability was deteriorated. Further, it can be seen that in reference example 3, the thickness of the intermediate layer was very large compared to the thickness of the outer adhesive layer, and therefore, the step coverage was deteriorated.

[ description of reference numerals ]

101: first outer adhesive layer

102: second outer adhesive layer

201: intermediate adhesive layer

301: first interface mixture layer

302: second interfacial mixture layer