JP5788102B2 - Non-crosslinking adhesive composition and adhesive sheet - Google Patents

Description

  The present invention protects optical members such as polarizing plates, liquid crystal panels, glass substrates for displays, and electronic parts such as semiconductor wafers and semiconductor packages, and protects them from scratches, damages and contamination when transporting and processing electronic components such as semiconductor wafers and semiconductor packages. It is related with the adhesive sheet used for the use etc. which do.

  In order to protect optical members and electronic components from scratches, breakage, and contamination during transportation and processing, it is common practice to attach an adhesive sheet. There are various optical members and electronic parts that are adherends, from smooth surfaces to rough ones, and the adhesive sheet must be well bonded to these surfaces. When transport and processing are finished, it is necessary to peel the adhesive without leaving an adhesive.

  As a surface protective sheet for various members, a surface protective sheet excellent in changes in adhesive strength over time has been reported (Patent Document 1). However, the surface protective sheet described in Patent Document 1 has a problem that the pressure-sensitive adhesive is hard and cannot be well bonded to an adherend having a rough surface.

  Moreover, the adhesive sheet which has the outstanding pick-up property is reported as an adhesive sheet used for the process of a silicon wafer (patent document 2). However, since the pressure-sensitive adhesive sheet described in Patent Document 2 contains a low molecular component, when the silicon wafer is diced, the chips are peeled off from the pressure-sensitive adhesive sheet and scattered, or the silicon wafer is contaminated with the pressure-sensitive adhesive. Sometimes things remained.

JP 2010-42580 A JP 2008-60434 A

  The present invention has been made in order to solve the above-described conventional problems, and it is satisfactorily bonded to an optical member, an electronic component, or the like without changing the adhesion to a smooth surface or a rough surface. An object of the present invention is to provide an adhesive sheet in which an adhesive does not remain on an adherend when it is peeled off.

In order to achieve the above-mentioned object, the following invention is provided.
(1) A main component is a (meth) acrylic acid ester copolymer having a weight average molecular weight of 700,000 to 2,000,000 and a dispersity of 5 or less and having no functional group that reacts with an isocyanate curing agent or an epoxy curing agent. A non-crosslinkable pressure-sensitive adhesive composition.
(2) The non-crosslinkable pressure-sensitive adhesive composition according to (1), wherein the functional group that reacts with an isocyanate curing agent or an epoxy curing agent is a carboxyl group or a hydroxyl group.
(3) A pressure-sensitive adhesive sheet obtained by laminating the non-crosslinkable pressure-sensitive adhesive composition according to (1) or (2) on at least one surface of a base film, and having a surface roughness Rz of 5 μm A pressure-sensitive adhesive sheet in which the force (A1) and the adhesive force (A2) to an adherend having a surface roughness Rz of 0.5 μm satisfy the following relationship.
A1 / A2 = 0.8 to 1.2

  By using the pressure-sensitive adhesive sheet of the present invention, the adhesion does not change depending on the surface roughness of the adherend, and the pressure-sensitive adhesive can be peeled without remaining on the adherend.

Sectional drawing which shows the adhesive sheet 1 which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an adhesive sheet 1 according to this embodiment. The pressure-sensitive adhesive sheet 1 has a base film 3 and a non-crosslinkable pressure-sensitive adhesive composition layer 5 provided on the base film 3. Below, the structure of each layer is demonstrated.

<Base film>
The base film is not particularly limited and can be appropriately selected from conventionally known resin films. Specifically, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, and polybutene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, and ethylene- (meth) acrylic acid ester copolymer. Ethylene copolymers such as polymers, engineering plastics such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polymethyl methacrylate, soft polyvinyl chloride, semi-rigid polyvinyl chloride, polyester, polyurethane, polyamide, polyimide natural rubber and synthesis Examples thereof include polymer materials such as rubber. Moreover, what mixed 2 or more types chosen from these groups, or the multilayered thing may be sufficient, and it can select arbitrarily by adhesiveness with an adhesive composition.

  The thickness of the base film is not particularly limited and can be appropriately determined depending on the purpose of use. Generally, it is 30-500 micrometers, Preferably, it is 50-200 micrometers.

<Non-crosslinking adhesive composition>
The non-crosslinkable pressure-sensitive adhesive composition laminated on the base film surface has a weight average molecular weight of 700,000 to 2,000,000 and a dispersity of 5 or less, and has a functional group that reacts with an isocyanate curing agent or an epoxy curing agent. No (meth) acrylic acid ester copolymer is the main component. “(Meth) acryl” means acrylic and / or methacrylic. The term “main component” means that the proportion of the (meth) acrylic acid ester copolymer in the non-crosslinkable pressure-sensitive adhesive composition is 50 to 100% by mass, and the proportion is preferably 80 to 100. % By mass.

  Examples of the monomer component constituting the (meth) acrylic acid ester copolymer according to this embodiment include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid. Isopropyl, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, (meth ) Heptyl acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, ( (Meth) isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (Meth) acrylic acid alkyl esters such as (meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, (meth) acrylic acid pentadecyl, (meth) acrylic acid hexadecyl, (meth) acrylic acid heptadecyl, (meth) acrylic acid octadecyl (Meth) acrylic acid cycloalkyl esters such as (meth) acrylic acid cyclohexyl; (meth) acrylic acid aryl esters such as phenyl (meth) acrylate, methoxyethyl (meth) acrylate, and ethoxyethyl (meth) acrylate And alkoxyalkyl (meth) acrylates such as nitrile monomers such as acrylonitrile and methacrylonitrile. (Meth) acrylic acid esters can be used alone or in combination of two or more.

  Since the (meth) acrylic acid ester copolymer according to this embodiment does not have a functional group that reacts with an isocyanate curing agent or an epoxy curing agent, a carboxyl group-containing monomer such as (meth) acrylic acid, ( (Meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid-4-hydroxybutyl, (meth) acrylic acid-6-hydroxyhexyl, (meth) acrylic acid-8 Polymerized without using a hydroxyl group-containing monomer such as hydroxyoctyl, (meth) acrylic acid-10-hydroxydecyl, (meth) acrylic acid-12-hydroxylauryl. That is, the acid value (JIS K0070 neutralization titration method) of the (meth) acrylic acid ester copolymer according to this embodiment is 0.1 mgKOH / g or less, and the hydroxyl value (JIS K0070 neutralization titration method) is 0. It means 1 mgKOH / g or less.

  Examples of isocyanate curing agents include isocyanate monomers such as tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate. And adduct isocyanate compounds obtained by adding these isocyanate monomers with trimethylolpropane; isocyanurates, burette type compounds, and addition reaction of known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like. Urethane prepolymer type isocyanate It is.

  Examples of the epoxy curing agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl. Aniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl Examples include aminophenylmethane, triglycidyl isocyanurate, m-N, N-diglycidylaminophenyl glycidyl ether, N, N-diglycidyl toluidine, and N, N-diglycidyl aniline.

  The weight average molecular weight (Mw) of the (meth) acrylic acid ester copolymer according to this embodiment is 700,000 to 2,000,000, more preferably 100 to 1,500,000. When the weight average molecular weight is less than 700,000, the adhesive may remain on the adherend during peeling. When the weight average molecular weight exceeds 2 million, the adhesion to the adherend having a rough surface is remarkably reduced. The adhesion changes depending on the surface roughness.

  Moreover, the dispersion degree of the (meth) acrylic acid ester copolymer according to this embodiment is 5 or less, and more preferably 2.5 to 4. Here, the degree of dispersion is a value obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn). When the degree of dispersion exceeds 5, the contribution of the low molecular component to the adhesion becomes large, and the adhesive changes when the adhesive remains on the adherend during peeling or the surface roughness of the adherend. . Further, the degree of dispersion can be lowered by the polymerization method, conditions and purification of the polymer, but the production cost is increased, so that it is preferably 2.5 or more. In addition, a weight average molecular weight (Mw) and a number average molecular weight (Mn) are polystyrene conversion molecular weights measured by gel permeation chromatography (GPC).

  The manufacturing method of the (meth) acrylic acid ester copolymer which concerns on this embodiment can be manufactured by a conventionally well-known method. For example, radical polymerization methods such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, a precipitation polymerization method, and an emulsion polymerization method can be appropriately selected. Among them, the emulsion polymerization method is more preferable because a polymer having a high molecular weight and a narrow dispersion degree is produced. As the radical polymerization initiator, various known azo and peroxide initiators can be used.

  The non-crosslinkable pressure-sensitive adhesive composition may contain any appropriate additive in addition to the (meth) acrylic acid ester copolymer as the main component, as long as it does not depart from the object of the present invention. Examples include ultraviolet curable resins, photopolymerization initiators, ultraviolet absorbers, tackifiers, curing agents, plasticizers, antioxidants, antistatic agents, polymerization inhibitors, silane coupling agents, and organic or inorganic fillers. .

  The ultraviolet curable resin is used when the non-crosslinkable pressure-sensitive adhesive composition of the present invention is cured by ultraviolet irradiation to facilitate peeling. Although ultraviolet curable resin is not specifically limited, For example, urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, etc. are mentioned.

  When the non-crosslinkable pressure-sensitive adhesive composition of the present invention is cured by ultraviolet irradiation, a photopolymerization initiator is added. The photopolymerization initiator is not particularly limited. For example, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler ketone, chlorothioxanthone, dodecyl thioxanthone, dimethylthioxanthone, diethylthioxanthone, benzyldimethylketanol, α-hydroxycyclohexyl ketone Examples include enilketone and 2-hydroxymethylphenylpropane.

Further, the non-crosslinkable pressure-sensitive adhesive composition of the present invention can be used as a pressure-sensitive adhesive sheet by laminating on at least one surface of a base film, and the surface roughness Rz of the adherend of the pressure-sensitive adhesive sheet is 5.0 μm. It is preferable that the adhesive force (A1) to the adherend and the adhesive force (A2) to the adherend having a surface roughness Rz of 0.5 μm satisfy the following relationship.
A1 / A2 = 0.8 to 1.2
By satisfy | filling said formula, the adhesive sheet can acquire favorable adhesiveness irrespective of the surface roughness of a to-be-adhered body.

  The thickness of the non-crosslinkable pressure-sensitive adhesive composition can be appropriately determined depending on the purpose of use and the adhesive strength. Generally, it is 1 to 300 μm, preferably 3 to 50 μm.

<Method for producing adhesive sheet>
The method for producing the pressure-sensitive adhesive sheet is not particularly limited, and can be selected from conventionally known coating methods. Examples thereof include roll coating methods such as reverse coating and gravure coating, spin coating methods, screen coating methods, fountain coating methods, dipping methods, and spray methods. After applying the solution of the non-crosslinkable pressure-sensitive adhesive composition, a non-crosslinkable pressure-sensitive adhesive composition layer having a predetermined thickness is obtained by volatilizing the solvent and water in the drying step. Moreover, you may apply | coat directly on a base film, and after apply | coating a non-crosslinkable adhesive composition on a release sheet, you may transcribe | transfer to a base film.

(Effect according to this embodiment)
By using the pressure-sensitive adhesive sheet according to the present embodiment, it is possible to satisfactorily adhere to an optical member, an electronic component, or the like without changing the adhesion to a smooth surface or a rough surface.

  Moreover, by using the adhesive sheet according to the present embodiment, the adhesive can be peeled without leaving the adherend.

  Next, in order to further clarify the effects according to the present embodiment, examples and comparative examples will be described in detail, but the present invention is not limited to these examples.

<Example 1>
[Production of non-crosslinkable adhesive composition]
(1) Preparation of acrylic acid ester copolymer Water, ethyl acrylate, butyl acrylate, acrylonitrile, and sodium lauryl sulfate as an emulsifier were charged into a polymerization reactor equipped with a thermometer and a stirrer. Two substitutions were performed to sufficiently remove oxygen. Thereafter, cumene hydroperoxide and sodium formaldehyde sulfoxylate were added, and emulsion polymerization was started under normal pressure at a temperature of 30 ° C. until the polymerization conversion reached 95%. The obtained emulsion polymerization solution was coagulated with a calcium chloride solution, washed with water and dried to obtain an acrylate copolymer having a weight average molecular weight of 700,000 and a dispersity (Mw / Mn) of 2.5. Since the monomer component of the acrylate copolymer of Example 1 is ethyl acrylate, butyl acrylate, and acrylonitrile, in Table 1, it describes as EA / BA / AN.

(2) Measurement of weight average molecular weight and degree of dispersion The GPC (gel permeation chromatography) method was used under the following conditions.
Analyzing device: Tosoh HLC-8120GPC
Column: manufactured by Tosoh Corporation, G7000HXL + GMHXL + GMHXL
Column size: 7.8mmφ × 30cm each 90cm in total
Column temperature: 40 ° C
Flow rate: 0.8 ml / min.
Injection volume: 100 μl
Eluent: Tetrahydrofuran Detector: Suggested refractometer Standard sample: Polystyrene

[Create adhesive sheet]
The obtained acrylic acid ester copolymer is dissolved in ethyl acetate, and 100 parts by weight of the acrylic acid ester copolymer is blended with 1 part by weight of a curing agent (Coronate L manufactured by Nippon Polyurethane Co., Ltd.). The composition was applied on a substrate film having a thickness of 100 μm (Lumirror U34 manufactured by Toray Industries, Inc.) so as to have a thickness of 10 μm, thereby preparing an adhesive sheet.

<Examples 2-5, Comparative Examples 1-4>
As compared with Example 1, the monomer components used in the production of the acrylic ester copolymer were changed as shown in Table 1. Moreover, polymerization conditions were changed so that the weight average molecular weight (Mw) and dispersity (Mw / Mn) of the obtained acrylic acid ester copolymer were as shown in Table 1. Except for these, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1, including the curing agent.

  The following evaluation was performed about the adhesive sheet obtained by the said Example and comparative example. The results are shown in Table 1.

(Acid value measuring method)
It measured by the neutralization titration method according to JISK0070 as shown below. First, the sample was weighed into an Erlenmeyer flask. Next, 100 ml of acetone and a few drops of a phenolphthalein solution as an indicator were added and shaken well until the sample was completely dissolved on a water bath. Next, the solution was titrated with a 0.1 mol / l potassium hydroxide ethanol solution, and the end point was when the light red color of the indicator lasted for 30 seconds. And the acid value was computed by following Formula.
A = B × f × 5.661 / S Formula (1)
(In the formula (1), A: acid value (mgKOH / g), B: amount of 0.1 mol / l potassium hydroxide ethanol solution used for titration (ml), f: 0.1 mol / l hydroxide) Factor (concentration correction factor) of potassium ethanol solution, S: mass of sample (g))

(Method for measuring hydroxyl value)
It measured by the neutralization titration method according to JISK0070 as shown below. First, 25 g of acetic anhydride was placed in a 100-ml volumetric flask, pyridine was added to make a total volume of 100 ml, and the mixture was thoroughly shaken to prepare an acetylating reagent. The acetylating reagent was kept out of contact with moisture, carbon dioxide and acid vapors and stored in a brown bottle. Next, the sample was weighed into a flat bottom flask, and 5 ml of an acetylating reagent was added to the flask using a total amount of bipet. Next, a small funnel was placed at the mouth of the flask, and the bottom was immersed in a glycerin bath at a temperature of 95-100 ° C. and heated for about 1 cm. In order to prevent the temperature of the flask neck from being heated by the heat of the glycerin bath, a cardboard disc with a round hole in it was put on the base of the flask neck. After 1 hour, the flask was taken out of the glycerin bath, allowed to cool, 1 ml of water was added from the funnel and shaken to decompose acetic anhydride. Furthermore, in order to complete decomposition, the flask was heated again in a glycerin bath for 10 minutes, allowed to cool, and then the funnel and the wall of the flask were washed with 5 ml of ethanol. A few drops of a phenolphthalein solution was added as an indicator, and titrated with a 0.5 mol / l potassium hydroxide ethanol solution. The end point was when the indicator was lightly red for about 30 seconds. The blank test was performed without a sample as described above. And the hydroxyl value was computed by following Formula.
A = ((BC) × f × 28.05 / S) + D Formula (2)
(In the formula (2), A: hydroxyl value (mgKOH / g), B: amount of 0.5 mol / l potassium hydroxide ethanol solution used in the blank test (ml), C: 0. 5 mol / l potassium hydroxide ethanol solution amount (ml), f: 0.5 mol / l potassium hydroxide ethanol solution factor (concentration correction factor), S: sample mass (g), D: acid value (mgKOH / g))

(Measurement method of adhesive strength)
(1) Adhesive force to an adherend having a surface roughness Rz = 5 μm (A1)
Three test pieces each having a width of 25 mm and a length of 300 mm were collected from each adhesive sheet and pasted on a SUS304 steel plate (thickness 1.5 mm to 2.0 mm) polished to have a surface roughness Rz = 5 μm. After that, a 2 kg rubber roller was pressure-bonded by reciprocating three times, and left for 1 hour, and then the adhesive strength was measured using a tensile tester conforming to JIS B 7721 whose measured value was in the range of 15 to 85% of its capacity. It was measured. The peeling angle was 180 degrees and the peeling speed was 300 mm / min. The measurement environment was adjusted to 23 ° C. and 50% RH.

(2) Adhesive force to adherend having surface roughness Rz = 0.5 μm (A2)
Three test pieces each having a width of 25 mm and a length of 300 mm were collected from each pressure-sensitive adhesive sheet, and the specimens were polished on a SUS304 steel plate (thickness 1.5 mm to 2.0 mm) having a surface roughness Rz = 0.5 μm. After sticking, a 2 kg rubber roller is pressure-bonded by reciprocating three times, and after standing for 1 hour, it is adhered using a tensile tester conforming to JIS B 7721 whose measured value falls within the range of 15 to 85% of its capacity. The force was measured. The peeling angle was 180 degrees and the peeling speed was 300 mm / min. The measurement environment was adjusted to 23 ° C. and 50% RH.

(Evaluation method of adherend selectivity)
In the case where the adhesive strengths A1 and A2 measured as described above satisfy the relationship of A1 / A2 = 0.8 to 1.2, the result is ◯, and when the relationship is not satisfied, the result is ×.

(Evaluation method of adhesive residue on adherend)
When the adhesive strengths of A1 and A2 were measured, the presence or absence of adhesive residue on the SUS plate after tape peeling was visually evaluated. The case where there was no adhesive residue on the SUS plate was marked with ◯, and the case where there was adhesive residue was marked with ×.

ＥＡ：アクリル酸エチル、ＢＡ：アクリル酸ブチル、ＡＮ：アクリロニトリル、ＭＥＡ：アクリル酸２−メトキシエチル、２ＨＥＡ：アクリル酸２−ヒドロキシエチル

EA: ethyl acrylate, BA: butyl acrylate, AN: acrylonitrile, MEA: 2-methoxyethyl acrylate, 2HEA: 2-hydroxyethyl acrylate

The acrylic acid ester copolymers according to Examples 1 to 5 and Comparative Examples 1 to 3 had an acid value of 0.1 mgKOH / g or less and a hydroxyl value of 0.1 mgKOH / g or less.
The acrylic ester polymer according to Comparative Example 4 has a hydroxyl group as a functional group that reacts with an isocyanate curing agent or an epoxy curing agent, and a hydroxyl value was 5.0 mgKOH / g.

  Further, from Table 1, a (meth) acrylic acid ester copolymer having a weight average molecular weight of 700,000 to 2,000,000 and a dispersity of 5 or less and having no functional group that reacts with an isocyanate curing agent or an epoxy curing agent is obtained. The pressure-sensitive adhesive sheets (Examples 1 to 5) obtained by laminating the non-crosslinkable pressure-sensitive adhesive composition as the main component on one surface of the base film adhere well to and adhere to adherends having different surface roughnesses. There was no adhesive residue on the adherend.

  On the other hand, when the weight average molecular weight of the acrylic ester copolymer was 500,000 (Comparative Example 1), adherend selectivity was good, but adhesive residue on the adherend was observed. This is presumably because the low molecular weight was low and the low molecular weight component was left behind.

  Moreover, when the weight average molecular weight of the acrylic ester copolymer was 2.1 million (Comparative Example 2), no adhesive residue was observed, but the adherend selectivity deteriorated. This is probably because the molecular weight was high and the adhesion to a rough surface was deteriorated.

  Furthermore, when the dispersity of the acrylic ester copolymer was 6 (Comparative Example 3), the adherend selectivity deteriorated, and adhesive residue on the adherend was also observed. This is considered that the low molecular component of the non-crosslinkable pressure-sensitive adhesive composition was adversely affected.

  Further, when 2-hydroxyethyl acrylate is used as the monomer component of the acrylic ester copolymer and has a hydroxyl group as a functional group that reacts with an isocyanate curing agent or an epoxy curing agent (Comparative Example 4), to the adherend No adhesive residue was observed, but the adherend selectivity deteriorated. This is presumably because the cross-linking reaction with the curing agent progressed and the adhesion to a rough surface was remarkably reduced.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1 ......... Adhesive sheet 3 ......... Base film 5 ......... Non-crosslinkable adhesive composition layer

Claims (2)

(Meth) acrylic acid ester copolymer having a weight average molecular weight of 700,000 to 2,000,000 and a dispersity of 2.5 to 4, and having no carboxyl group or hydroxyl group, which is a functional group that reacts with an isocyanate curing agent ; A non-crosslinkable pressure-sensitive adhesive composition containing at least an isocyanate curing agent . A non-crosslinkable pressure-sensitive adhesive composition according to claim 1, which is a pressure-sensitive adhesive sheet laminated on at least one surface of a base film, and is polished to have a surface roughness Rz of 5 μm (thickness 1.5 mm). To 2.0 mm) and the adhesion (A2) to the SUS304 steel plate (thickness 1.5 mm to 2.0 mm) polished so that the surface roughness Rz is 0.5 μm. Meet the adhesive sheet.
A1 / A2 = 0.8 to 1.2

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