TWI698511B - Adhesive composition and adhesive tape - Google Patents

Abstract

Disclosed are: an adhesive composition comprising an acrylic copolymer (A) containing 10 to 20% by weight of an alkyl(meth)acrylate (A1) having an alkyl group of 1 to 3 carbon atoms, 50 to 80% by weight of an alkyl(meth)acrylate (A2) having an alkyl group of 4 to 12 carbon atoms, 10 to 15% by weight of a carboxyl group-containing monomer (A3), 0.01 to 0.5% by weight of a hydroxyl group-containing monomer (A4), and 1 to 5% by weight of vinyl acetate (A5) as polymer chain-forming components, in which the copolymer obtained by using a peroxide-based polymerization initiator has a weight-average molecular weight of 950,000 to 2,000,000 and a calculated Tg of -55 or less, a crosslinking agent (B), a silane coupling agent (C) and an antioxidant (D); and an adhesive tape prepared by using the same.

Description

Adhesive composition and adhesive tape

The present invention relates to an adhesive composition with excellent rebound resistance, load resistance, narrow edge wet and heat resistance, processability, impact resistance and water resistance, and an adhesive tape using the same.

The display screens of portable electronic devices such as smart phones and tablet terminals are generally constructed by combining touch panels and liquid crystal modules. Moreover, in recent years, the enlargement of the display screen and the thinning of the casing have been continuously developed. Flexible printed circuit boards (FPC, Flexible Printed Circuits) are integrated into the liquid crystal module. As the display screen becomes larger and the casing becomes thinner, the FPC is further bent into an acute angle, and it is often applied Structure of strong rebound force. Furthermore, the impact-resistant waterproof double-sided adhesive tape used to fix the housing and the top panel has also been narrowed as the LCD screen becomes larger. Therefore, in order to fix the housing-LCD-top panel, the adhesive tape is required to be able to withstand the rebound force of the FPC from the inside, and also have adhesiveness such as impact resistance or water resistance that can withstand external forces. In the case of insufficient adhesion, peeling of the top panel due to strong internal stress, or peeling or water seepage due to external stress, resulting in damage to the machine. In addition, in terms of processing adaptability, if the tape is narrowed and the adhesive is soft when pressed into elongated strips, frame shapes, etc., splashed paste, paste particles, etc. will adhere to the knife. Cut smoothly, thereby making the yield worse. Adhesives for repulsion resistance generally use adhesives with a higher theoretical Tg. In most cases, there is no problem in terms of processability. question. In addition, there is also a case in which the rebound resistance can be improved by adding a high softening point adhesive imparting resin of 10 to 30% relative to the solid content of the adhesive. However, in this case, load resistance, impact resistance, and water resistance are poor.

Since there is no such adhesive tape that can withstand internal and external stresses, the bonding method is changed. However, new equipment needs to be invested due to changes in methods, and the difficulty or workability of secondary processing becomes a problem.

Patent Document 1 describes the following double-sided adhesive tape, which has an adhesive layer on both sides of a foam substrate, and the adhesive layer contains a (meth)acrylate having a carbon number of 4 to 12 and a carboxyl group The vinyl monomer is used as an acrylic copolymer as the monomer component, and an acrylic adhesive composition with polymerized rosin ester to provide adhesion to the resin.

Patent Document 2 describes a double-sided adhesive tape in which an adhesive layer containing an acrylic copolymer and an adhesion-imparting resin is provided on both sides of a base material containing a polyethylene foam.

Patent Document 3 describes the following double-sided adhesive tape, which is used for fixing components of electronic equipment, and is characterized by comprising: a substrate; a first adhesive layer provided on one side of the substrate; and 2 Adhesive layer, which is provided on the other side of the substrate; and at least one of the first adhesive layer and the second adhesive layer contains an acrylic polymer, and has a weight average molecular weight of 20,000 or less and a monomer An acrylic oligomer different from the above acrylic polymer.

Patent Document 4 describes the following adhesive composition, which contains: an acrylic copolymer (A) containing an alkyl (meth)acrylate (A1) having a C 4-12 alkyl group: 50~ 90% by mass, carboxyl group-containing monomer (A2) 3-20% by mass, hydroxyl-containing monomer (A3) 3-20% by mass, and alkane having 1 to 3 carbon atoms Alkyl (meth)acrylate (A4) 3-15% by mass as a constituent, a weight average molecular weight of 700,000 to 2 million, a theoretical Tg of -40°C or less, and a hydroxyl and carboxyl group; and a crosslinking agent (B).

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2010-260880

Patent Document 2: Japanese Patent Laid-Open No. 2009-084367

Patent Document 3: Japanese Patent Laid-Open No. 2013-163781

Patent Document 4: International Publication No. 2014/002203

With the miniaturization, thinning, and large screen of products in recent years, even narrow adhesive tapes require sufficient water resistance or load resistance. In view of this aspect, the present invention is related to the above and the adhesive tape Those who have further improved related conventional technologies.

That is, the object of the present invention is to provide an adhesive composition with excellent properties such as water resistance, load resistance, processability, impact resistance, narrow edge resistance to humidity and heat, resistance to artificial sebum, and artificial perspiration oil, and to use it. The adhesive tape.

The present invention is an adhesive composition comprising: an acrylic copolymer (A), which contains an alkyl (meth)acrylate (A1) having a carbon number of 1 to 3, 10-20% by mass, Alkyl (meth)acrylate (A2) with a C4-12 alkyl group (A2) 50-80% by mass, carboxyl group-containing monomer (A3) 10-15% by mass, hydroxyl-containing monomer (A4) 0.01~0.5 mass%, and vinyl acetate (A5) 1~5 mass% It is a component of the polymer chain, and the weight average molecular weight of the copolymer obtained by using a peroxide-based polymerization initiator is 950,000 to 2 million, and the theoretical Tg is below -55°C; crosslinking agent (B); silane Coupling agent (C); and antioxidant (D).

In addition, the present invention is an adhesive tape, which is attached to a polyolefin resin substrate on one or both sides with an adhesive layer formed from the adhesive composition of the present invention, and the polyolefin resin substrate is in the processing direction The bending moment of the (MD, Machine Direction) and the transverse direction (TD, Transverse Direction) is 5gf/cm or more, the shear deformation rate of the adhesive tape during heating is 150% or less, and the breaking force is 70N/cm ² or more.

In addition, the present invention is an adhesive tape having an adhesive layer formed of the adhesive composition of the present invention on one or both sides of a polyester resin substrate.

Although the adhesive composition of the present invention contains a relatively large number of alkyl (meth)acrylates (A1) with a C1-C3 alkyl group as a high Tg monomer, it has impact resistance at low temperatures It is excellent, and it is also excellent in load resistance, narrow edge wet and heat load resistance, processability, water resistance, artificial sebum resistance, and artificial sweat oil resistance. Moreover, the single-sided or double-sided adhesive tape of the present invention is excellent in each of the above-mentioned characteristics, so it can be used for various applications in fields requiring such characteristics.

1‧‧‧Double-sided adhesive tape

1a‧‧‧Substrate

1b‧‧‧Adhesive layer

2‧‧‧SUS304 hook

3‧‧‧Adhesive body

4‧‧‧weight

5‧‧‧Polyimide film

6‧‧‧1.5mm thick polycarbonate hook

7‧‧‧1.9mm thick tempered glass plate

8‧‧‧2.0mm thick SUS304 board

9‧‧‧0.5mm thick SUS304BA board

10‧‧‧1kgf weight

11‧‧‧10gf stainless steel ball

Xi‧‧‧Add sample length

Xt‧‧‧Sample deformation

FIG. 1 is a schematic diagram for explaining the evaluation method of the load resistance of the embodiment.

Fig. 2 is a schematic diagram for explaining the evaluation method of the low-temperature impact resistance of the narrow edge of the embodiment.

Fig. 3 is a schematic diagram for explaining the evaluation method of the breaking force of the embodiment.

Fig. 4 is a schematic diagram for explaining the evaluation method of the rebound resistance of the embodiment.

Fig. 5 is a schematic diagram for explaining the evaluation method of the rebound resistance of the embodiment.

Fig. 6 is a schematic diagram for explaining the evaluation method of the shear deformation rate during heating in the embodiment.

FIG. 7 is a schematic diagram for explaining the evaluation method of the wet and heat load resistance of the narrow edge of the embodiment.

Fig. 8 is a schematic diagram for explaining the method of evaluating the impact resistance of the falling ball of the embodiment.

<Adhesive composition>

The adhesive composition of the present invention is a composition containing acrylic copolymer (A), crosslinking agent (B), silane coupling agent (C), and antioxidant (D).

The acrylic copolymer (A) contains alkyl (meth)acrylate (A1) having an alkyl group with carbon atoms of 1 to 3, and a (meth)acrylic acid alkyl group with an alkyl group of 4 to 12 carbon atoms An acrylic copolymer in which ester (A2), carboxyl group-containing monomer (A3), hydroxyl group-containing monomer (A4), and vinyl acetate (A5) are the constituent components of the polymer chain.

Alkyl (meth)acrylate (A1) is an alkyl (meth)acrylate with an alkyl group of 1 to 3 carbon atoms, which is used to improve rebound resistance, load resistance, processability, narrow edge resistance The weight-bearing ingredient of damp heat. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. Among them, methyl (meth)acrylate is preferred. The content of the alkyl (meth)acrylate (A1) is 10-20% by mass, preferably 12-16% by mass in 100% by mass of the constituent components (monomer unit) of the acrylic copolymer (A). The lower limit of these ranges is meaningful in terms of characteristics such as rebound resistance, load resistance, processability, and narrow edge wet and heat resistance. In addition, the upper limit is significant in terms of characteristics such as narrow-edge low-temperature impact resistance and water resistance.

The alkyl (meth)acrylate (A2) is an alkyl (meth)acrylate having an alkyl group having 4 to 12 carbon atoms. Specific examples include: butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isobutyl (meth)acrylate Octyl ester, isononyl (meth)acrylate, lauryl (meth)acrylate. Among them, 2-ethylhexyl (meth)acrylate is preferred. The content of the alkyl (meth)acrylate (A2) is 50 to 80% by mass, preferably 65 to 79% by mass in 100% by mass of the constituent components (monomer unit) of the acrylic copolymer (A).

The carboxyl-containing monomer (A3) is a component used to improve rebound resistance, load resistance, processability, narrow-edge low-temperature impact resistance, and water resistance. Specific examples include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, 2-carboxy-1-butene, 2-carboxy-1-pentene, 2-carboxyl -1-hexene, 2-carboxy-1-heptene. The content of the carboxyl group-containing monomer (A3) is 10-15% by mass, preferably 10-12% by mass in 100% by mass of the constituent components (monomer unit) of the acrylic copolymer (A). The lower limit of these ranges is meaningful in terms of rebound resistance, load resistance, processability, narrow-edge wet and heat resistance, narrow-edge low-temperature impact resistance, and water resistance.

The hydroxyl-containing monomer (A4) is a component used to improve rebound resistance, load resistance, processability, and low-temperature impact resistance of narrow edges. Specific examples include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The content of the hydroxyl-containing monomer (A4) is 0.01 to 0.5% by mass in 100% by mass of the constituent components (monomer unit) of the acrylic copolymer (A), preferably 0.05 to 0.15% by mass. The upper limit of these ranges suppresses the time-dependent change of the adhesive tape under heating and damp heat, and maintains sufficient rebound resistance, load resistance, processability, narrow edge low temperature impact resistance, and water resistance. significance.

Vinyl acetate (A5) is used to improve rebound resistance, load resistance, and add Workability, narrow-edge, heat-resistant and heavy-duty components. The content of vinyl acetate (A5) is 1 to 5% by mass, preferably 2 to 4% by mass in 100% by mass of the constituent components (monomer unit) of the acrylic copolymer (A). The lower limit of these ranges is meaningful in terms of characteristics such as rebound resistance, load resistance, processability, and narrow edge wet and heat resistance. In addition, the upper limit value is significant in terms of characteristics such as load resistance, narrow-edge wet and heat resistance, and narrow-edge low-temperature impact resistance.

The acrylic copolymer (A) is obtained by copolymerizing at least the components (A1) to (A5) described above. The polymerization method is not particularly limited. In terms of ease of polymer design, radical solution polymerization is preferred. In addition, an acrylic syrup containing the acrylic copolymer (A) and its monomers may be prepared first, and the crosslinking agent (B) and an additional photopolymerization initiator may be blended and polymerized in the acrylic syrup. When producing the acrylic copolymer (A), it is also possible to copolymerize monomers other than the components (A1) to (A5) within a range that does not impair the effects of the present invention.

The weight average molecular weight of the acrylic copolymer (A) is 950,000 to 2 million, preferably 1 to 1.5 million. The lower limit of these ranges is meaningful in terms of load resistance, narrow edge wet and heat load resistance, and processability. In addition, the upper limit has significance in terms of the coating properties of the adhesive composition. The weight average molecular weight is a value measured by Gel Permeation Chromatography (GPC). The theoretical Tg of the acrylic copolymer (A) is -55°C or less, preferably -55 to -75°C. The theoretical Tg is a value calculated according to the formula of FOX.

In the present invention, the above-described acrylic copolymer (A) is used as the resin component, but other types of additive components may be used in combination with a range that does not impair the effects of the present invention. However, it is preferable not to contain an adhesion-imparting resin. The reason is that if the adhesive imparting resin is used together, the low molecular weight components in the adhesive increase, and Reduce the load-bearing resistance, artificial sebum resistance, and narrow-edge resistance to humidity and heat.

The crosslinking agent (B) used in the present invention is a compound formulated to react with the acrylic copolymer (A) to form a crosslinked structure. Particularly preferred is a compound that can react with the carboxyl group and/or hydroxyl group of the acrylic copolymer (A). Furthermore, in terms of water resistance, load resistance, processability, narrow-edge low-temperature impact resistance, narrow-edge wet and heat load resistance, artificial sebum resistance, and artificial sweat oil resistance, an isocyanate-based crosslinking agent is preferred. Specific examples of the isocyanate-based crosslinking agent include toluene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and modified prepolymers thereof. Two or more of these can be used in combination. The blending amount of the crosslinking agent (B) is preferably 0.02 to 1 part by mass, more preferably 0.3 to 0.6 part by mass relative to 100 parts by mass of the acrylic copolymer (A).

Silane coupling agent (C) is a component used to improve rebound resistance and narrow edge resistance to humidity and heat. Particularly preferred is a silane coupling agent containing glycidyl groups. Specific examples include: 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyl Diethoxysilane, 3-glycidoxypropyl triethoxysilane, tris-(trimethoxysilylpropyl) isocyanurate. Two or more of these can be used in combination. The compounding amount of the silane coupling agent (C) is preferably 0.01 to 0.5 parts by mass, more preferably 0.02 to 0.5 parts by mass, and particularly preferably 0.05 to 0.3 parts by mass relative to 100 parts by mass of the acrylic copolymer (A).

Antioxidant (D) is a component used to improve rebound resistance and narrow edge resistance to humidity and heat. Particularly preferred is a hindered phenol antioxidant. The compounding amount of the antioxidant (D) is preferably 0.02 to 1.0 parts by mass, and more preferably 0.07 to 0.7 parts by mass relative to 100 parts by mass of the acrylic copolymer (A).

The adhesive composition of the present invention may further contain light-shielding filler or pigment. Specific examples of light-shielding fillers include carbon black, carbon nanotubes, and black inorganic fillers. Specific examples of pigments include carbon black, aniline black, acetylene black, and Ketjen black.

<Polyolefin substrate adhesive tape>

The polyolefin substrate adhesive tape of the present invention has an adhesive layer formed of the adhesive composition of the present invention on one or both sides of the polyolefin resin substrate. The thickness of the adhesive layer is preferably 5 to 100 μm, more preferably 10 to 80 μm. The adhesive layer can also be formed only on one side of the substrate, but it is preferably formed on both sides to make a double-sided adhesive tape.

The adhesive layer can be formed by cross-linking the adhesive composition of the present invention. For example, the adhesive composition can be coated on a substrate, and a cross-linking reaction can occur by heating to form an adhesive layer on the substrate. In addition, the adhesive composition can also be coated on release paper or other films, cross-linked by heating to form an adhesive layer, and the adhesive layer can be attached to a single side of the substrate or Double-sided. When applying the adhesive composition, for example, a coating device such as a roll coater, a die nozzle coater, and a die lip coater can be used. In the case of heating after coating, the solvent in the adhesive composition can also be removed simultaneously with the cross-linking reaction by heating.

The polyolefin-based resin base material particularly preferably includes a polyolefin-based resin foam. As a specific example of polyolefin resin, polyethylene or polypropylene can be mentioned.

The thickness of the polyolefin-based resin substrate is preferably 0.05 to 2.0 mm.

The bending moment of the polyolefin resin substrate in the MD direction (length direction) and TD direction (width direction) is 5 gf/cm or more, preferably 7 gf/cm or more. With the base material having such a bending moment, the adhesive tape will not be deformed, and exhibits excellent narrow-edge processability, which in turn also exhibits excellent narrow-edge resistance to heat and humidity.

The shear deformation rate of the adhesive tape when heated is 150% or less, preferably 130% or less. The adhesive tape is not easily deformed by having such a shear deformation rate when heated, and exhibits excellent impact resistance, load resistance, and narrow edge wet heat resistance.

The breaking force of the adhesive tape is 70 N/cm ² or more, preferably 90 N/cm ² or more. The adhesive tape exhibits excellent impact resistance, load resistance, and narrow edge wet and heat resistance by having such breaking force.

<Polyester substrate adhesive tape>

The polyester substrate adhesive tape of the present invention has an adhesive layer formed of the adhesive composition of the present invention on one or both sides of the polyester resin substrate. The method of forming the adhesive layer is the same as that of the polyolefin substrate adhesive tape described above. The polyester resin base material may be any of crystalline, amorphous, or foamable.

The polyester resin substrate is usually used in the form of a resin film. Its thickness is 0.002~0.05mm, preferably 0.006~0.038mm. As a specific example of the polyester resin, polyethylene terephthalate can be cited.

[Example]

Hereinafter, the present invention will be explained in more detail with examples and comparative examples. In the following description, "parts" means parts by mass, and "%" means parts by mass.

<Production Examples 1-20 (Preparation of Acrylic Copolymer (A))>

To a reaction device equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, add the components (A1)~(A5) shown in Table 1 in the amount (%), ethyl acetate, and positive ten as a chain transfer agent. Dialkyl mercaptan, and 0.1 part of lauryl peroxide as a peroxide radical polymerization initiator. Seal the reaction device with nitrogen and place it in the nitrogen flow The mixture was stirred at 68°C for 3 hours, and thereafter, polymerization reaction was performed at 78°C for 3 hours. After that, it was cooled to room temperature, and ethyl acetate was added. In this way, an acrylic copolymer (A) with a solid content concentration of 30% was obtained.

Table 1 shows the weight average molecular weight (Mw) and theoretical Tg of each acrylic copolymer. The weight average molecular weight (Mw) is a value obtained by measuring the molecular weight of the acrylic copolymer in terms of standard polystyrene by the GPC method under the following measuring equipment and conditions.

. Device: LC-2000 series (manufactured by JASCO Corporation)

. Column: Shodex KF-806M×2, Shodex KF-802×1

. Eluent: Tetrahydrofuran (THF)

. Flow rate: 1.0mL/min

. Column temperature: 40℃

. Injection volume: 100μL

. Detector: Refractive Index (RI, Refractive Index)

. Measurement sample: Dissolve the acrylic polymer in THF to prepare a solution with a concentration of 0.5% by weight of the acrylic polymer, and filter to remove dirt by using a filter.

The theoretical Tg is a value calculated according to the formula of FOX.

<Examples 1-19 and Comparative Examples 1-10 (Preparation of adhesive composition and production of adhesive tape)>

As shown in Table 2, to 100 parts of the solid content of the acrylic copolymer (A) obtained in Production Examples 1-20, the crosslinking agent (B), the silane coupling agent (C), and the antioxidant (D) were added and combined Mix to prepare an adhesive composition.

The adhesive composition was coated on a release paper treated with silicone so that the thickness after drying became 0.075 mm. Then, the solvent is removed and dried at 110° C., and cross-linking reaction occurs to form an adhesive layer. The adhesive layer was bonded to both sides of a 0.15mm thick polyolefin-based foamed resin substrate (e-beam cross-linked polyethylene foamed resin, foaming ratio 1.8~2 times) with a bending moment of 12gf/cm. Then, it was cured at 40°C for 3 days to obtain a polyolefin-based foamed resin substrate double-sided adhesive tape.

<Example 20>

The adhesive composition of Example 1 was bonded to a 0.1mm thick polyolefin-based foamed resin substrate with a bending moment of 6.0gf/cm (e-beam cross-linked polyethylene foamed resin, foaming ratio 1.5~2.2 times ) Of both sides. Then, it was cured at 40°C for 3 days to obtain a polyolefin-based foamed resin substrate double-sided adhesive tape.

<Example 21>

The adhesive composition of Example 1 was laminated to a 0.2mm thick polyolefin-based foamed resin substrate with a bending moment of 14.0gf/cm (e-beam cross-linked polyethylene foamed resin, foaming ratio 2.5~3.5 times ) Of both sides. Then, it was cured at 40°C for 3 days to obtain a polyolefin-based foamed resin substrate double-sided adhesive tape.

<Reference Example 1 (Making of Adhesive Tape)>

The adhesive composition of Example 1 was bonded to a 0.15mm thick polyolefin-based foamed resin substrate (e-beam cross-linked polyethylene foamed resin, foaming ratio 3 times) with a bending moment of 1.0 gf/cm Double-sided. Then, it was cured at 40°C for 3 days to obtain a polyolefin-based foamed resin substrate double-sided adhesive tape.

<Reference Example 2 (Making of Adhesive Tape)>

The adhesive composition of Example 1 was bonded to a 0.15mm thick polyolefin-based foamed resin substrate (e-beam cross-linked polyethylene foamed resin, foaming ratio 2.5 times) with a bending moment of 2.5 gf/cm Double-sided. Then, it was cured at 40°C for 3 days to obtain a polyolefin-based foamed resin substrate double-sided adhesive tape.

<Example 22>

With respect to 100 parts of the solid content of the acrylic copolymer (A) obtained in Production Example 1, 0.45 parts of crosslinking agent (B1), 0.15 parts of silane coupling agent (C1), and 0.07 parts of antioxidant (D1) were added and mixed, And prepare the adhesive composition.

The adhesive composition was coated on a release paper treated with silicone so that the thickness after drying became 0.019 mm. Then, the solvent is removed and dried at 100° C., and a cross-linking reaction occurs to form an adhesive layer. The adhesive layer was bonded to both sides of a 0.012 mm thick biaxially stretched polyester film (polyethylene terephthalate film). Then, it was cured at 40°C for 3 days to obtain a polyester film substrate double-sided adhesive tape.

<Comparative Example 11 (Making of Adhesive Tape)>

Except for using the acrylic copolymer (A) obtained in Production Example 19, an adhesive composition was prepared in the same manner as in Example 22 to obtain a polyester-based film substrate double-sided adhesive tape.

The abbreviations in Table 1 are as follows.

"MA": methyl acrylate

"2-EHA": 2-ethylhexyl acrylate

"BA": n-butyl acrylate

"AA": Acrylic

"4-HBA": 4-hydroxybutyl acrylate

"Vac": Vinyl acetate

The abbreviations in Table 2 are as follows.

"B1": Isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane, trade name Corona L-45E)

"C1": Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-403)

"C2": Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-402)

"C3": Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBE-403)

"C4": Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBE-402)

"D1": Antioxidant (manufactured by BASF, trade name Irganox 1010)

<Evaluation Test A>

The following methods were used to evaluate the polyolefin-based foamed resin substrate double-sided adhesive tapes obtained in Examples 1 to 21, Comparative Examples 1 to 10, and Reference Examples 1 to 2. The results are shown in Tables 3-6.

(Waterproof)

Cut the double-sided adhesive tape into a frame with a width of 1mm and a width of 63mm×118mm, peel off a release paper and attach it to a 2.0mm thick glass plate, then peel off another release paper and attach a 2.0mm thick glass plate. Using an autoclave, the sample was pressurized (0.5 MPa) at 23°C for 1 minute. Then, based on JIS IPX7 (waterproof standard), the sample was temporarily immersed in water, and the waterproofness was evaluated according to the following criteria. In addition, the sample was made in the same manner as above, and based on JIS IPX8 (waterproof standard), it was submerged under water with a depth of 10cm, and an autoclave was used to perform pressurization treatment at 23°C and 0.5MPa for 1 hour, and according to the following The benchmark evaluates water resistance.

"○": Water has not penetrated into the frame.

"×": Water penetrates into the frame.

(Artificial sebum resistance, artificial finger fat resistance)

Cut the double-sided adhesive tape into a frame with a width of 1mm and a width of 63mm×118mm, and peel off Separate a release paper and attach it to a 2.0mm thick glass plate, then peel off another release paper and attach a 2.0mm thick glass plate. Using an autoclave, the sample was pressurized at 23° C. and 0.5 MPa for 1 minute. Then, the sample was immersed in artificial sebum (33.3% triolein, 20.0% oleic acid, 13.3% squalene, 33.4% myristyl octadodecylate) or artificial sebum. Lipid (manufactured by Lin Chun Yao Industrial Co., Ltd.) in 72 hours. Take out the sample and let it stand for 24 hours in an environment of 85°C and 85%RH, and then place it in a normal environment for 24 hours. The sample was visually observed, and the artificial sebum resistance and artificial finger grease resistance were evaluated according to the following criteria.

"○": Artificial sebum liquid and artificial finger fat liquid have not penetrated into the frame.

"×": Artificial sebum and artificial finger fat penetrate into the frame.

(Base material bending moment)

The base material is cut into a thin strip with a width of 38mm and a length of 50mm. Based on JIS P 8125, using a TABER stiffness tester manufactured by Toyo Seiki Seisakusho, install a 10g weight on the pendulum and read the bending speed of 3°/sec. , The scale when the bending angle is 15°, set it as the measured value. Then, this measured value is substituted into the following calculation formula, and the bending moment (M) in MD direction and TD direction is calculated.

M=38.0nk/w

M: bending moment (gf/cm)

n: the reading of the scale (1 when the weight is 10g)

k: average torque per scale (gf/cm)

w: width of test piece

(Load resistance)

Cut the double-sided adhesive tape into a size of 25mm×25mm, and peel off a release paper. Then, as shown in FIG. 1, the double-sided adhesive tape 1 (base material 1a, adhesive layer 1b) is attached to the hook 2 made of SUS304, and then another release paper is peeled off and attached to the adherend 3. As the adherend 3, SUS304, a polycarbonate sheet, an acrylic sheet, an electro-galvanized (EGI, Electro-Galvanized) steel sheet, a galvalume steel sheet, and a glass sheet are used. Then, a load of 700 gf (weight 4) was applied to the hook 2 made of SUS304, kept at 85°C for 24 hours, and the load resistance was evaluated according to the following criteria.

"○": Hook 2 has not dropped within 24 hours.

"X": Hook 2 falls within 60 minutes.

(Processability)

Cut the double-sided adhesive tape into 10 strips with a size of 5mm×125mm, maintain this state (that is, each adhesive tape obtained after the fine cutting maintains the adjacent state when it is finely cut), and place it at 65°C and 80%RH 1 day. After that, for each strip, the release paper was peeled off in the 180° direction, the adhesion to the adjacent part was visually confirmed, and the workability was evaluated according to the following criteria.

"○": There is almost no adhesion to the adjacent part, and it can be successfully peeled without peeling the adjacent part.

"×": There is obvious adhesion on the adjacent part, and the adjacent part is peeled off at the same time.

(Narrow edge low temperature impact resistance)

Cut the double-sided adhesive tape into a frame with a width of 0.6mm and 63mm×118mm, peel off a release paper and attach it to the adherend 3 (a 1.5mm thick polycarbonate board), then peel off another release paper and Attach it to the adherend 7 (1.9mm thick tempered glass plate). Such as As shown in Fig. 2, after adjusting the laminated member with a 2.0 mm thick SUS304 plate 8 so that the weight becomes 160 gf, it is cured for 60 minutes. The sample was allowed to fall freely in the shear direction from a height of 1.5M in an environment of -20°C, and the impact resistance was evaluated according to the following criteria.

"○": After 20 drops, there is no peeling of the adhesive part and interlayer failure of the substrate.

"×": After 20 drops, there was peeling of the subsequent part and interlayer failure of the substrate.

(Breaking force)

Cut the double-sided adhesive tape into a size of 25mm×25mm, and peel off a release paper. Then, as shown in Figure 3, the double-sided adhesive tape 1 (base material 1a, adhesive layer 1b) is attached to the hook 2 made of SUS304, and then another release paper is peeled off and attached to the adherend 3 (2.0mm thick) SUS304BA board), cured for 60 minutes at 23°C and 50%RH. Then, the hook 2 made of SUS304 was stretched upward at a speed of 300 mm/min, and the strength [N/cm ² ] when the foam was broken was measured.

(Rebound resistance)

Peel off one of the release paper of the double-sided adhesive tape 1 cut into 1mm×20mm, and attach it to one end of the polyimide film 5 with a thickness of 125μm and 20mm×60mm as shown in Figure 4, at 23℃, 50% Cure for 60 minutes under RH environment. After that, the polyimide film 5 was bent as shown in FIG. 5, and the adhesive tape 1 was attached to the adherend 3 (a 1.5mm thick polycarbonate plate) at 85°C and 85%RH. Leave it in the environment for 72 hours, visually confirm the peeling of the adhesive part, and evaluate the rebound resistance according to the following criteria.

"○": There is no peeling of the adhesive part after 72 hours.

"×": After 72 hours, there was peeling of the subsequent part.

(Shear deformation rate during heating)

Cut the double-sided adhesive tape into a size of 25mm×25mm, and peel off a release paper. Then, as shown in Figure 6, the double-sided adhesive tape 1 (base material 1a, adhesive layer 1b) is attached to the SUS304BA board 9 with a thickness of 0.5mm, a width of 30mm and a length of 100mm, and then another release paper is peeled off and attached To SUS304BA board 9 of the same size, cure for 60 minutes at 23°C and 50%RH. Then, a weight 10 of 1 kgf was suspended from its lower end, heated at 120°C for 30 minutes, and heated at 135°C for 30 minutes. The amount of deformation was measured visually with a magnifying glass, and the shear deformation rate during heating was calculated according to the following formula (△ Sr).

△Sr=(Xi+Xt)/Xi×100

△Sr: Shear deformation rate during heating (%)

Xi: Add sample length (mm)=25(mm)

Xt: sample deformation (mm)

(Narrow edge resistance to heat and humidity)

Cut the double-sided adhesive tape into a frame with a width of 0.5mm, 0.6mm, 0.8mm, 1.0mm and 63mm×118mm, and peel off a release paper. Then, as shown in FIG. 7, the double-sided adhesive tape 1 is attached to the 1.5mm thick polycarbonate hook 6, and then another release paper is peeled off and attached to the adherend 3 (2.0mm thick glass plate) , Cured for 60 minutes at 23°C and 50%RH. Then, a load of 200 gf (weight 4) was applied to the glass hook 6 and kept at 40° C. and 90% RH for 24 hours, and the load resistance was evaluated according to the following criteria.

"○": Hook 6 has not dropped within 24 hours.

"×": Hook 6 dropped within 60 minutes.

The evaluation results in Tables 3 to 6 show that in Examples 1 to 21 using the adhesive composition of the present invention, all characteristics are excellent.

On the other hand, in Comparative Example 1 using the acrylic copolymer 13 without the component (A5), comparison with the acrylic copolymer 14 without the component (A1) Example 2, Comparative Example 3 of Acrylic Copolymer 15 with too little amount of component (A1), Comparative Example 4 of Acrylic Copolymer 16 with too high Tg and too much amount of component (A5), Using too low Mw Comparative Examples 5 and 6 of Acrylic Copolymers 17 and 18, Comparative Example 7 of Acrylic Copolymer 19 with too little amount of component (A3), Comparative Example of Acrylic Copolymer 20 with too much amount of component (A4) 8. In Comparative Example 9 using a composition not containing the component (C), and Comparative Example 10 using a composition not containing the component (D), any characteristics are inferior.

In addition, since Examples 1 to 21 are examples of manufacturing the adhesive tape of the present invention, all characteristics are excellent. On the other hand, although Reference Examples 1 and 2 use the adhesive composition of the present invention, the base material is different from the base material of the adhesive tape of the present invention, and therefore, either characteristic is inferior.

<Evaluation Test B>

The polyester film substrate double-sided adhesive tape obtained in Example 22 and Comparative Example 11 was evaluated by the following method. The results are shown in Tables 7-8.

Furthermore, the reasons for the difference in the evaluation items, sample size, and test conditions of the evaluation test A and evaluation test B are: the use and required performance of the polyolefin-based foamed resin substrate adhesive tape and the polyester-based film substrate double-sided adhesive tape They are slightly different from each other. Polyolefin-based foamed resin substrate adhesive tapes are used to fix parts that are preferably foamed elastic substrates, such as housings and top panels, and require narrowing corresponding to their dimensions and also require water resistance. Or adherence. On the other hand, polyester-based film substrate double-sided adhesive tape is used to fix LCD panels and backlight units, for example, and requires a narrower size corresponding to its size, and its adhesion needs to be able to withstand the rebound of the frequently applied FPC Force or impact when falling. In the case of insufficient adhesion, peeling of the LCD panel and the backlight unit occurs, As a result, light leakage occurs.

(Waterproof)

The size of the double-sided adhesive tape is cut into a frame with a width of 1mm and 45mm×65mm, and the JIS IPX8 (waterproof standard) conditions are changed to 23℃, 0.2MPa, 30 minutes of pressure treatment. In addition, use and< The water resistance of the evaluation test A> is tested in the same way, and the water resistance is evaluated according to the following criteria.

"○": Water has not penetrated into the frame.

"×": Water penetrates into the frame.

(Artificial sebum resistance, artificial finger fat resistance)

Cut the size of the double-sided adhesive tape into a frame with a width of 1mm and 45mm×65mm. After immersing it in artificial sebum or artificial finger grease for 24 hours, place the sample at 85℃ and 85%RH for 72 hours. Otherwise, use the same method as the artificial sebum resistance and artificial finger fat resistance in <Evaluation Test A>, and evaluate the artificial sebum resistance and artificial finger fat resistance according to the following criteria.

"○": Artificial sebum liquid and artificial finger fat liquid have not penetrated into the frame.

"×": Artificial sebum and artificial finger fat penetrate into the frame.

(Processability)

The double-sided adhesive tape was finely cut into 10 strips with a size of 1mm×125mm. Except for this, the same method as the processability of <Evaluation Test A> was used to test, and the processability was evaluated according to the following criteria.

"○": There is almost no adhesion to the adjacent part, and the adjacent part will not be peeled off The next can be successfully peeled off.

"×": There is obvious adhesion on the adjacent part, and the adjacent part is peeled off at the same time.

(Falling ball impact resistance)

Cut the double-sided adhesive tape into 2 strips with a size of 1mm×50mm and peel off a release paper. Then, as shown in Figure 8, the adherend 3 (1.5mm thick polycarbonate board) was attached in parallel at 65mm intervals, and then another release paper was peeled off and attached to the adherend 7 (1.9mm Thick tempered glass plate). The laminated member was allowed to stand at 85°C and 85%RH for 72 hours, and then at 23°C and 50%RH for 1 hour. On the adherend 3 (polycarbonate plate of 1.5 mm thick) side of the sample, a 10 gf stainless steel ball 11 was freely dropped from a height of 0.5M to apply an impact, and the impact resistance of the falling ball was evaluated according to the following criteria.

"○": No peeling of components caused by impact.

"×": There is peeling of components caused by impact.

(Impact resistance of falling ball at low temperature)

In the above-mentioned impact resistance of falling balls, after leaving it at 23°C and 50%RH for 1 hour, it is then left at -20°C for 1 hour. Then, in an environment of -20°C, on the side of the adherend 3 (1.5mm thick polycarbonate plate) of the sample, a 10gf stainless steel ball is freely dropped from a height of 0.3M and an impact is applied according to the following standards Evaluate the impact resistance of the low temperature drop ball.

"○": No peeling of components caused by impact.

"×": There is peeling of components caused by impact.

(Rebound resistance)

Peel off one of the release papers of the double-sided adhesive tape 1 cut into 1mm×10mm and attach it to one end of the polyimide film 5 with a thickness of 75μm and 10mm×30mm as shown in Figure 4, at 23°C, 50% Cure for 60 minutes under RH environment. After that, the polyimide film 5 was bent in the shape shown in FIG. 5 so that the folded part (the part of 20 mm in FIG. 5) became 4 mm, and the adhesive tape 1 was attached to the adhered Body 3 (polycarbonate board with a thickness of 1.5 mm) was placed in an environment of 85°C for 72 hours. The peeling of the adhered part was visually confirmed, and the rebound resistance was evaluated according to the following criteria.

"○": After 72 hours, there is no peeling of the adhesive part.

"×": After 72 hours, there was peeling of the subsequent part.

(Narrow edge load resistance)

Cut the size of the double-sided adhesive tape into a frame with a width of 1mm and 45mm×65mm, apply a load of 200gf (weight 4), and set the test environment to 85°C for 24 hours. In addition to this, use and <evaluation test A > The narrow edge is tested in the same way as the heat and humidity resistance of the narrow edge, and the narrow edge is evaluated according to the following criteria.

"○": Hook 6 has not dropped within 24 hours.

"×": Hook 6 dropped within 60 minutes.

(Narrow edge resistance to heat and humidity)

Cut the size of the double-sided adhesive tape into a frame with a width of 1mm and 45mm×65mm, apply a load of 50gf (weight 4), set the test environment to 85°C, 85%RH, and 24 hours. <Evaluation Test A> The narrow-edge damp and heat resistance is the same as the test method, and the narrow-edge damp and heat resistance is evaluated according to the following criteria Sex.

"○": Hook 6 has not dropped within 24 hours.

"×": Hook 6 dropped within 60 minutes.

The evaluation results in Tables 7 to 8 show that in Example 22 using the adhesive composition of the present invention, all characteristics are excellent. On the other hand, in Comparative Example 11 using the acrylic copolymer 19 in which the amount of the component (A3) was too small, each characteristic was poor.

1‧‧‧Double-sided adhesive tape

1a‧‧‧Substrate

1b‧‧‧Adhesive layer

2‧‧‧SUS304 hook

3‧‧‧Adhesive body

4‧‧‧weight

Claims (7)

An adhesive composition containing: acrylic copolymer (A), containing 10-20% by mass of alkyl (meth)acrylate (A1) having an alkyl group with 1 to 3 carbon atoms, and having carbon atoms Alkyl (meth)acrylate (A2) with 4 to 12 alkyl groups (A2) 50 to 80% by mass, carboxyl group-containing monomer (A3) 10 to 15% by mass, hydroxyl group-containing monomer (A4) 0.01 to 0.5 Mass%, and vinyl acetate (A5) 1~5 mass% as the constituent components of the polymer chain, and the weight average molecular weight of the copolymer obtained by using a peroxide-based polymerization initiator is 950,000 to 2 million, theoretically Tg is below -55°C; crosslinking agent (B); silane coupling agent (C); and antioxidant (D). The adhesive composition of claim 1, wherein the silane coupling agent (C) contains a glycidyl group, and the blending amount is 0.01 to 0.5 parts by mass relative to 100 parts by mass of the acrylic copolymer (A). The adhesive composition of claim 1, wherein the crosslinking agent (B) contains at least an isocyanate-based crosslinking agent. The adhesive composition of claim 1, wherein the antioxidant (D) contains a hindered phenol-based antioxidant. An adhesive tape having an adhesive layer formed of the adhesive composition of claim 1 on one or both sides of a polyolefin resin substrate, and the polyolefin resin substrate is in the MD and TD directions The bending moment is 5gf/cm or more, the shear deformation rate of the adhesive tape when heated is 150% or less, and the breaking force is 70N/cm ² or more. Such as the adhesive tape of claim 5, wherein the thickness of the adhesive layer is 5-100 μm. An adhesive tape having an adhesive layer formed from the adhesive composition of claim 1 on one or both sides of a polyester resin substrate.

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