JP5835525B1 - Adhesive composition and adhesive film - Google Patents

Abstract

The problem to be solved by the present invention is to provide a pressure-sensitive adhesive composition having excellent adhesion, excellent wettability to glass and plastic substrates, and less contamination to dryers, etc. It is to provide an adhesive film obtained by drying and curing. The present invention is 1 selected from the group consisting of a polyurethane (A) having two or more hydroxyl groups, a polyisocyanate crosslinking agent (B), an ester compound having an epoxy group, diisononyl adipate and bis (2-ethylhexyl) adipate. The present invention provides a pressure-sensitive adhesive composition containing an ester compound (C) and an organic solvent (D), and a pressure-sensitive adhesive film obtained by using the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition of the present invention is less contaminated with a dryer or the like, and the resulting pressure-sensitive adhesive film has excellent adhesive strength and wettability to glass and plastic substrates. Moreover, it is excellent also in removability and can be used especially suitably for a surface protection film.

Description

  The present invention relates to a pressure-sensitive adhesive composition having excellent adhesive strength, excellent wettability to glass and plastic substrates, and having little contamination to a dryer, and a pressure-sensitive adhesive film obtained using the same.

  In recent years, surface protective films have been widely used for the purpose of preventing dirt and scratches on the surface of glass and plastic substrates. As the configuration of the surface protective film, a configuration of a plastic film such as a PET (polyethylene terephthalate) film, a pressure-sensitive adhesive layer, and a release film is generally used. As a pressure-sensitive adhesive used for the pressure-sensitive adhesive layer, Acrylic adhesives are widely used.

  However, when an acrylic adhesive is used, there are problems such as insufficient wettability to glass and plastic substrates, and insufficient foam removal at the time of coating or release film application, and surface protection. It is desired to improve the efficiency of film production.

  On the other hand, use of a pressure-sensitive adhesive using polyurethane has been studied as a pressure-sensitive adhesive for a surface protective film. As the above-mentioned polyurethane pressure-sensitive adhesive for a surface protective film, for example, a pressure-sensitive adhesive composition containing a polyurethane having a hydroxyl group, a polyisocyanate crosslinking agent, isopropyl palmitate and an organic solvent is disclosed (for example, see Patent Document 1). ).

  However, the pressure-sensitive adhesive composition has a high contamination property to a dryer or the like due to a volatile component at the time of drying an organic solvent, and improvement has been desired.

JP 2011-190420 A

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive composition having excellent adhesion, excellent wettability to glass and plastic substrates, and less contamination to dryers, etc. It is to provide an adhesive film obtained by drying and curing.

  The present invention is 1 selected from the group consisting of a polyurethane (A) having two or more hydroxyl groups, a polyisocyanate crosslinking agent (B), an ester compound having an epoxy group, diisononyl adipate and bis (2-ethylhexyl) adipate. The present invention provides a pressure-sensitive adhesive composition containing an ester compound (C) and an organic solvent (D), and a pressure-sensitive adhesive film obtained by using the pressure-sensitive adhesive composition.

  The pressure-sensitive adhesive composition of the present invention is less contaminated with a dryer or the like, and the resulting pressure-sensitive adhesive film has excellent adhesive strength and wettability to glass and plastic substrates. Moreover, it is excellent also in removability and can be used especially suitably for a surface protection film.

  The pressure-sensitive adhesive composition of the present invention comprises a polyurethane (A) having two or more hydroxyl groups, a polyisocyanate crosslinking agent (B), an ester compound having an epoxy group, diisononyl adipate and bis (2-ethylhexyl) adipate. It contains at least one ester compound (C) selected from the group and an organic solvent (D).

  The polyurethane (A) has two or more hydroxyl groups for crosslinking with the polyisocyanate crosslinking agent (B), and preferably has 2 to 4 hydroxyl groups.

  As said polyurethane (A), what is obtained by reacting polyol (a1) and polyisocyanate (a2) can be used, for example.

  Examples of the polyol (a1) include polyether polyol, polyester polyol, polycarbonate polyol, polybutadiene polyol, polycaprolactone polyol, acrylic polyol, dimer diol, polyisoprene polyol, and the like. These polyols may be used alone or in combination of two or more. Moreover, it is preferable that it is the range of 2-4 as a hydroxyl group of the said polyol. Among these, it is preferable to use a polyether polyol and / or a polyester polyol from the viewpoint that the crosslinkability, the mechanical strength of the adhesive film, the heat resistance and the heat and moisture resistance can be further improved, and the polyether triol and / or the polyester diol are used. More preferably, it is used.

  The number average molecular weight of the polyol (a1) is preferably in the range of 700 to 6,000, more preferably in the range of 800 to 4,000, from the viewpoint that the adhesive strength and the mechanical strength of the pressure-sensitive adhesive film can be further improved. More preferably. In addition, the number average molecular weight of the said polyol (a1) shows the value measured on condition of the following by the gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

  Examples of the polyisocyanate (a2) include aromatic polyisocyanates such as xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4 Aliphatic or alicyclic polyisocyanates such as' -dicyclohexylmethane diisocyanate, diisocyanate methylcyclohexane, and tetramethylxylylene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, it is preferable to use an aliphatic or alicyclic polyisocyanate from the viewpoint that the discoloration over time can be further suppressed while maintaining the adhesive force.

  As a method for producing the polyurethane (A), for example, there is a method in which both are reacted so that the molar ratio of the hydroxyl group of the polyol (a1) is excessive with respect to the molar ratio of the isocyanate group of the polyisocyanate (a2). Can be mentioned. In addition, you may perform the said reaction in the organic solvent (D) mentioned later. The polyol (a1) may be charged all at once or may be charged in two or more times while controlling the reaction. The molar ratio (NCO / OH) between the hydroxyl group of the polyol (a1) and the isocyanate group of the polyisocyanate (a2) is 0.3 from the viewpoint of ease of reactivity control and mechanical strength of the adhesive film. The range is preferably from 0.99 to 0.99, and more preferably from 0.4 to 0.9.

  The number average molecular weight of the polyurethane (A) is in the range of 20,000 to 500,000 from the viewpoint of further improving the adhesive strength, wettability to glass and plastic substrates and the mechanical strength of the pressure-sensitive adhesive film. The range of 30,000 to 300,000 is more preferable. In addition, the number average molecular weight of a polyurethane (A) shows the value measured similarly to the number average molecular weight of the said polyol (a1).

  Examples of the polyisocyanate crosslinking agent (B) include a polyisocyanate compound similar to the polyisocyanate (a2); a compound obtained by reacting the polyisocyanate compound with a polyhydric alcohol such as trimethylolpropane and pentaerythritol; It is possible to use an isocyanurate compound of a polyisocyanate compound; a burette compound of the polyisocyanate compound; an adduct thereof. These polyisocyanate crosslinking agents may be used alone or in combination of two or more.

  The polyisocyanate crosslinking agent (B) is used in an amount of 1 to 100 parts by mass with respect to 100 parts by mass of the polyurethane (A) from the viewpoint of adhesive strength, wettability to glass and plastic substrates, and mechanical strength of the adhesive film. The range is preferably 30 parts by mass, and more preferably 5 to 20 parts by mass.

  As the ester compound (C), an ester compound having an epoxy group, adipic acid, which is excellent in wettability and adhesion to glass and plastic substrates and has little contamination to a dryer, etc. It is essential to use at least one selected from the group consisting of diisononyl and bis (2-ethylhexyl) adipate.

  Examples of the ester compound having an epoxy group include epoxidized fats and oils such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized cottonseed oil; compounds obtained by epoxidizing a fatty acid having 2 to 10 carbon atoms, and 1 carbon atom. A reaction product with a compound having a hydroxyl group such as -8 polyhydric alcohol and phenol can be used. These compounds may be used alone or in combination of two or more.

  The amount of the ester compound (C) used is 5 to 50 with respect to 100 parts by mass of the polyurethane (A) from the viewpoints of adhesive strength, wettability to glass and plastic substrates, and contamination to dryers and the like. It is preferable that it is the range of a mass part, and the range of 10-40 mass parts is more preferable.

  Examples of the organic solvent (D) include ester solvents such as ethyl acetate, methyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and aliphatic hydrocarbons such as heptane, hexane, cyclohexane, and methylcyclohexane. Solvent: aromatic hydrocarbon solvent such as toluene, o-xylene, m-xylene, p-xylene; alcohol solvent such as methanol, ethanol, isopropyl alcohol, isobutanol, sec-butanol, tertiary butanol, etc. can be used. . These organic solvents may be used alone or in combination of two or more.

  The amount of the organic solvent (D) used is preferably in the range of 20 to 200 parts by mass with respect to 100 parts by mass of the polyurethane (A) from the viewpoint of production stability and coatability, and 40 to 100 The range of parts by mass is more preferable.

  The pressure-sensitive adhesive composition of the present invention contains the components (A) to (D) as essential components, but may further contain other additives as necessary.

  Examples of the other additives include rust preventives, thixotropic agents, dispersants, sensitizers, urethanization catalysts, polymerization inhibitors, leveling agents, tackifiers, foam stabilizers, and the like. These additives may be used alone or in combination of two or more.

  As a method for producing the pressure-sensitive adhesive film of the present invention, for example, the polyisocyanate crosslinking agent (B) and the ester compound (C) are added to a mixture in which the polyurethane (A) is dissolved or dispersed in the organic solvent (D). A method for producing a pressure-sensitive adhesive film by adding and mixing to produce a pressure-sensitive adhesive composition, coating the pressure-sensitive adhesive composition on a base material (glass or plastic base material), drying and curing, and the like. .

  Examples of the plastic substrate include polyester such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polyolefin, polyacrylate, polyvinyl chloride, polyethylene, polypropylene ethylene vinyl alcohol, polyurethane, polyamide, and polyimide. Sheet or film can be used. The surface of these plastic substrates may be subjected to mold release treatment, antistatic treatment, corona treatment and the like. Moreover, although the thickness of these said plastic base materials changes according to the use for which an adhesive film is used, it is the range of 10-100 micrometers, for example.

  Examples of the method for applying the pressure-sensitive adhesive to the substrate include a method using a roll coater, a gravure coater, a reverse coater, a spray coater, an air knife coater, a die coater and the like.

  The thickness of the coated pressure-sensitive adhesive layer after drying the organic solvent (D) varies depending on the use for which the pressure-sensitive adhesive film is used, but is, for example, in the range of 5 to 100 μm.

  Examples of a method for drying the pressure-sensitive adhesive composition after coating the pressure-sensitive adhesive composition on the substrate include a method of drying at 50 to 120 ° C. for 30 seconds to 10 minutes. Moreover, you may cure in the range of 30 to 50 degreeC from the point which accelerates | stimulates hardening reaction from the point which accelerates | stimulates hardening reaction after drying, for example.

  The surface energy of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film obtained by the above method is preferably in the range of 45 to 55 mN / m from the viewpoint that wettability to glass or a plastic substrate can be further improved. In addition, the surface energy of the adhesive layer of the said adhesive film shows the value measured as follows.

First, each contact angle ((theta) (degree)) was measured about the surface of the adhesive layer of an adhesive film using water and a methylene iodide. Next, using this measured value and the surface energy value of the contact angle measurement liquid, the surface energy (γ _s ) was calculated by the following equation.
γ _s = γ _s ^d + γ _s ^p (1)
γ _L = γ _L ^d + γ _L ^p (2)
(1 + cos θ) γ _L = 2 (γ _s ^d γ _L ^d ) ^1/2 +2 (γ _s ^p γ _L ^p ) ^1/2 (3)

γ _s ^d : Dispersion component in the surface energy of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film
gamma _{s ^p:} polar component of the surface energy of the adhesive layer of the adhesive film
γ _L : surface energy of water or methylene iodide
γ _L ^d : Dispersion component in the surface energy of water or methylene iodide
γ _L ^p : Polar component in the surface energy of water or methylene iodide
The surface energy values of water and methylene iodide are as follows.
Water: γ _L ^d = 21.8 mJ / m ² , γ _L ^p = 51.0 mJ / m ²
Methylene iodide: γ _L ^d = 49.5 mJ / m ² , γ _L ^p = 1.3 mJ / m ²

  The contact angle of water and methylene iodide is approximately 1 μL of water on the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% Rh according to JISZ8703-1983. Alternatively, a drop of methylene iodide was dropped, and measurement was performed by a three-point method 30 seconds after dropping using a surface contact angle meter (“CA-X” manufactured by Kyowa Interface Science Co., Ltd.).

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Synthesis Example 1]
<Synthesis of polyurethane (A-1)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 56.6 parts by mass of polyester diol (Kuraray Co., Ltd. “Kuraray polyol P1010”, number average molecular weight; 1,000), hexamethylene diisocyanate 19 parts by weight, 104 parts by weight of toluene and 0.039 parts by weight of dioctyltin dilaurate were charged and heated to 90 ° C. When the isocyanate group content (NCO%) became the same as the theoretical value, it was cooled to 40 ° C. Next, 220.5 parts by mass of polyethertriol (“GL-3000” manufactured by Sanyo Chemical Industries, Ltd., number average molecular weight; 3,000) and 93.4 parts by mass of toluene were charged and heated to 90 ° C. After confirming that NCO% was 0.05% or less, the system was cooled to obtain polyurethane (A-1) having a nonvolatile content of 60% by mass, a viscosity of 5,000 mPa · s, and a number average molecular weight of 60,000. .

[Example 1]
18 parts by mass of bis (2-ethylhexyl) adipate relative to 100 parts by mass of the polyurethane (A-1) obtained in Synthesis Example 1, hexamethylene diisocyanate trimethylolpropane adduct ("Duranate P103-" manufactured by Asahi Kasei Corporation) 75E ", containing 25% by mass of an ethyl acetate solution) and 127.5 parts by mass of ethyl acetate, and 87.5 parts by mass of ethyl acetate were blended to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was applied to the surface of a 50 μm thick polyethylene terephthalate (PET) film (hereinafter abbreviated as “substrate PET”) so that the film thickness after drying was 15 μm. And dried at 80 ° C. for 3 minutes. Then, it was bonded to a 38 μm thick PET film (hereinafter abbreviated as “release PET film”) having a release treatment on the surface and aged at 40 ° C. for 3 days to obtain an adhesive film.

[Examples 2-3, Comparative Examples 1-2]
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive film were obtained in the same manner as in Example 1 except that the ester compound (C) to be used was changed as shown in Table 1.

[Evaluation method of adhesive strength]
What cut | judged the adhesive film obtained by the Example and the comparative example to 25 mm x 120 mm was made into the test piece. The test piece was attached to a glass plate and reciprocated twice with a 2 kg roll. After 24 hours from pasting, 23 ° C. The 180 ° C. peel strength was measured under a tensile rate of 30 m / min in an atmosphere of 50% humidity, and the adhesive strength (N / 25 mm) was obtained.

[Method for evaluating wettability]
What cut | judged the adhesive film obtained by the Example and the comparative example into the rectangle of width 5cm and length 15cm was used as the test piece. Next, the release PET film is peeled off, both ends of the test piece are held by hand, bent, and the center of the exposed pressure-sensitive adhesive layer is brought into contact with the glass plate. The number of seconds to stick to the plate was measured.

[Contamination evaluation method]
A test piece was prepared by cutting the adhesive films obtained in Examples and Comparative Examples into squares each having a length of 10 cm. The release PET film of the obtained test piece was peeled off, and the mass (hereinafter abbreviated as “mass before exposure”) was measured. Separately from this, a substrate PET cut into a 10 cm square was prepared, and the mass (hereinafter abbreviated as “substrate PET mass”) was measured. Next, the test piece from which the release PET film was peeled was exposed for 30 minutes in an atmosphere at 100 ° C., and then the mass of the test piece (hereinafter abbreviated as “mass after exposure”) was measured. The mass reduction rate of the pressure-sensitive adhesive layer was calculated by the following calculation formula (4) using the obtained mass value, and the contamination property was evaluated as follows. In addition, when the mass reduction rate of the pressure-sensitive adhesive layer was less than 10%, it was evaluated as “◯”, and when it was 10% or more, it was evaluated as “x”.

“Eposizer W-121”: an ester compound having an epoxy group manufactured by DIC Corporation

  The pressure-sensitive adhesive composition of the present invention was found to have excellent adhesive strength, excellent wettability to glass and plastic substrates, and little contamination to dryers and the like.

  On the other hand, Comparative Examples 1 and 2 were embodiments in which isopropyl palmitate or isopropyl myristate was used instead of the ester compound (C), but the contamination of the dryer was significant.

Claims (1)

Polyurethane (A) having a number average molecular weight in the range of 20,000 to 500,000, polyisocyanate crosslinking agent (B), epoxidized soybean oil, epoxidized linseed oil, epoxidized cottonseed oil, carbon atom 1 or more types selected from the group consisting of a reaction product of a compound obtained by epoxidizing a fatty acid of 2 to 10 and a polyhydric alcohol or phenol having 1 to 8 carbon atoms, diisononyl adipate and bis (2-ethylhexyl) adipate It is an adhesive film which has an adhesive layer which is a hardened | cured material of the adhesive composition containing the ester compound (C) and organic solvent (D), and the surface energy of the said adhesive layer is the range of 45-55 mN / m. A pressure-sensitive adhesive film characterized by being