JPH1017843A - Photocurable adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photocurable adhesive sheet which exhibits sufficient wetting properties and sufficient early-stage adhesion to an adherend. SOLUTION: This compsn. comprises 100 pts.wt. liq. photopolymerizable resin having a cationically polymerizable group and a viscosity of 1-30,000cp as measured with a Brookfield viscometer at 23 deg.C, 40-500 pts.wt. solid photopolymerizable resin having a cationically polymerizable group and a softening point of 40-200 deg.C, and a cathionic photopolymn. initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photocurable adhesive composition.

[0002]

2. Description of the Related Art In recent years, adhesive sheets and tapes using a photocurable resin can simplify the complicated and uneven work of applying an adhesive, improve the working environment, and improve productivity. It has been noticed because it can be improved. Such a photocurable adhesive sheet is one in which a photopolymerizable resin component is processed into a sheet or tape shape, and the components of the adhesive sheet are cured by light irradiation to exhibit adhesiveness. From the viewpoint that such a photocurable adhesive sheet is suitable for bonding to an adherend that is vulnerable to heating and bonding processing in a construction where a heating process is extremely difficult, a thermosetting resin using a thermosetting resin is used. It has a great advantage compared to the adhesive sheet.

In a photocurable adhesive sheet, it is important to simultaneously realize both "sheet handling property" and "wetting property to an adherend". That is, in order to realize the handleability of the sheet, it is necessary that the constituent components of the adhesive sheet have a certain degree of hardness at room temperature. However, when the components of the adhesive sheet have a certain degree of hardness at room temperature, the wettability to the adherend surface tends to be insufficient, and the final interfacial adhesion with the adherend surface is insufficient. become.

As a method for solving such a problem, Japanese Patent Laid-Open Publication No. Hei 6-285724 discloses a method in which an adhesive sheet is formed by using a collapsible jelly-like material formed by adding a gelling agent to a liquid photocurable resin composition. A method of forming is disclosed. According to the publication, it is described that by using such a collapsible jelly-like material as a constituent component of an adhesive sheet, both the handleability of the sheet and the wettability to an adherend can be compatible.

[0005]

However, in the method disclosed in the above publication, the resin composition is gelled to improve the handleability of the sheet, so that the wettability or followability to the surface of the adherend is reduced. There has been a problem that it is still insufficient and it is not possible to obtain sufficient initial adhesiveness.

An object of the present invention is to provide a photocurable adhesive composition having sufficient wettability to the surface of an adherend and sufficient initial adhesiveness, which could not be realized by the prior art. It is in.

[0007]

The photocurable adhesive composition of the present invention has a cationically polymerizable group in the molecule and has a viscosity at 23 ° C. of from 1 to 30,000 cp measured by a B-type viscometer.
100 parts by weight of liquid photopolymerizable resin (A), 40 to 500 parts by weight of solid photopolymerizable resin (B) having a cationically polymerizable group in the molecule and having a softening point of 40 ° C to 200 ° C, and light It is characterized by comprising a cationic polymerization initiator (C).

The liquid photopolymerizable resin (A) has a cationically polymerizable group in the molecule and is measured by a B-type viscometer.
It has a viscosity at 3 ° C. of 1 to 30,000 cps. The cationically polymerizable group is not particularly limited as long as it is a polymerizable group capable of photocationic polymerization.Moreover, if the viscosity is too high, it may be difficult to form a sheet, The viscosity at 23 ° C. measured with a B-type viscometer is 1 to
30,000 cps, preferably 1-20000 c
ps.

Examples of the liquid photopolymerizable resin (A) include glycidyl ether-based epoxy resins such as bisphenol A-based epoxy resin, bisphenol F-based epoxy resin, halogenated epoxy resin, cycloaliphatic epoxy resin, and glycidyl. Ester epoxy resin, glycidylamine epoxy resin, dimethylaminostyrene polymer, α-methylstyrene polymer, isobutyl vinyl ether polymer, p-methoxystyrene polymer and the like, but in that high adhesion is obtained. Epoxy resins are preferably used.

The bisphenol A-based epoxy resin has the following general formula:

[0011]

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[0012] As a commercial product, "Epicoat 8
27 "(manufactured by Yuka Shell Epoxy, viscosity 9000-11)
000 cps), "Epicoat 828" (manufactured by Yuka Shell Epoxy, viscosity 12000-15000 cps),
"Epototh-115" (Toto Kasei Co., Ltd., viscosity 700-
1100 cps), "ADEKARESIN EP-4100"
(Manufactured by Asahi Denka Co., Ltd., viscosity: 12000 to 15000 cps), and the bisphenol F-based epoxy resin has the following general formula

[0013]

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[0014] As a commercial product, "Epototo Y
DF-8170 "(Toto Kasei Co., Ltd., viscosity 500-200)
0 cps) and "ADEKARESIN EP-4901" (manufactured by Asahi Denka Co., Ltd., viscosity: 2000 to 4000 cps). Further, as the cycloaliphatic epoxy resin, vinylcyclohexane dioxide is used, and as the glycidyl ester epoxy resin, diglycidyl phthalate, diglycidyl tetrahydrophthalate, and the like are listed. As the glycidylamine epoxy resin, N is used. ,
N-diglycidylaniline, tetraglycidylaminodiphenylmethane and the like can be mentioned.

The solid photopolymerizable resin (B) has a cationically polymerizable group in the molecule and has a softening point of 40 to 200 ° C. The cationically polymerizable group is not particularly limited as long as it is a polymerizable group capable of photocationic polymerization, and a resin having a low softening point is difficult to be in a solid form at room temperature when the softening point is low. When it is used, it becomes difficult to sufficiently obtain the handleability of the sheet, and when it is high, it becomes difficult to sufficiently obtain the initial adhesiveness.
° C, preferably 40 to 150 ° C.

As the solid photopolymerizable resin (B),
For example, novolak-based epoxy resins, naphthalene-based epoxy resins, and the novolak-based epoxy resins include, for example, the following general formula

[0017]

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And "Epotote YDCN-701" (softening point of 60 to 70) as a commercial product.
° C), "Epototh YDCN-703" (softening point 75 ~
85 ° C.), “Epototo YDCN-704” (softening point 8
5 to 95 ° C.) or more, manufactured by Toto Kasei Co., Ltd., “Epicoat 100
1 (softening point 64 ° C.), “Epicoat 1055” (softening point 93 ° C.), “Epicoat 1004F” (softening point 103
° C) or more, manufactured by Yuka Shell Epoxy.

The solid photopolymerizable resin (B) used in the present invention has a softening point of 40 ° C. to 200 ° C. If the softening point is lower than this, it is difficult to form a solid at room temperature, and if a resin having a low softening point is used, the handling properties of the sheet will be insufficient.

The solid photopolymerizable resin (B) is used in an amount of 40 to 500 parts by weight based on 100 parts by weight of the liquid photopolymerizable resin (A).
More preferably, it is used in an amount of 100 to 300 parts by weight. If the blending amount of the solid photopolymerizable resin (B) is too small, the handleability of the sheet will be insufficient, and if the blending amount is too large, the initial adhesiveness may be insufficient.

The cationic photopolymerization initiator used in the present invention is not particularly limited as long as it can initiate cationic polymerization. For example, an aromatic diazonium salt represented by the following formula: , Aromatic iodonium salts, aromatic sulfonium salts, and the like.

[0022]

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[0023]

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[0024]

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Further, specifically, as an antimony hexafluoride-based aromatic sulfonium salt, "Adekaoptomer SP-170" represented by the following general formula and the like can be mentioned.

[0026]

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The addition amount of the cationic photopolymerization initiator is as follows:
The amount is generally about 0.5 to 3.0 parts by weight based on 100 parts by weight of the total of the liquid photopolymerizable resin (A) and the solid photopolymerizable resin (B).

The photocurable adhesive composition of the present invention contains the liquid photopolymerizable resin (A), the solid photopolymerizable resin (B), and the cationic photopolymerization initiator (C). However, if necessary, a resin such as a polymer mainly composed of an acrylate ester or a natural rubber may be contained.
If necessary, other additives may be contained.

The photocurable adhesive composition may be produced by any method, for example, by heating the liquid photopolymerizable resin (A) and the solid photopolymerizable resin (B) at 50 to 300 ° C.
After heating and melting, the mixture is uniformly stirred and mixed using a mixer. Further, the heating and melting temperature is preferably from 100 to 200C.

The photocurable adhesive composition of the present invention is generally used after being formed into a sheet, or is formed into a sheet by impregnating a core material such as glass cloth, carbon cloth and various nonwoven fabrics. Is done. In addition, the photocurable adhesive composition of the present invention may be, for example, one molded and processed on a release sheet.

In the present invention, the liquid photopolymerizable resin (A) and the solid photopolymerizable resin (B) are mixed, but these resins are in a compatible state or in a very good dispersion state. Preferably, they are mixed.

In the photocurable adhesive composition of the present invention, the photocationic polymerization reaction generally proceeds slowly when irradiated with light. Since this is a dark reaction, there is no need to irradiate light until the end of polymerization, and when bonding the sheet-like material, for example, by irradiating the sheet-like material with light and immediately bonding it to the adherend, Thereafter, the curing reaction proceeds, and the desired adhesiveness can be obtained. In addition, light may be applied after bonding to the adherend.

The irradiation conditions such as the wavelength, intensity and irradiation time of the light to be irradiated at this time are appropriately adjusted depending on the activity of the photoinitiator, the activity of the photopolymerizable resin used, and the like. Usually, the wavelength peak is preferably from 350 to 400 nm, more preferably from 360 to 380 nm, in order to allow the light to sufficiently enter the inside. And is preferably 10 to 300 mW / cm ² as light intensity, more preferably 25~100mW / cm ^2, the irradiation time is preferably 1 to 10 minutes, more preferably 3 to 6 minutes.

As a method of sticking or applying, the photocurable adhesive composition formed into the above-mentioned sheet shape is first stuck to the adherend, and then irradiated with light such as ultraviolet rays under the above conditions. There is a method of attaching to one adherend.

In the photocurable adhesive composition of the present invention, a liquid photopolymerizable resin (A) having a low cohesive force is used, which is mixed with a solid photopolymerizable resin (B) at a predetermined ratio. As a result, a moderately aggregated state can be obtained. Therefore, good wettability to the adherend and initial adhesion can be obtained.

[0036]

DETAILED DESCRIPTION OF THE INVENTION EXAMPLE 1 Table 1 shows the liquid photopolymerizable resin, solid photopolymerizable resin, and a polymerization initiator, were mixed in proportions shown in Table 1. This mixed composition was heated to 150 ° C. and sufficiently stirred, and then applied to a 100 μm-thick polyethylene terephthalate film to obtain a 300 μm-thick photocurable adhesive composition sheet. Further, the mixed composition was impregnated into a glass cloth having a thickness of 250 μm and a basis weight of 300 g / cm ² ,
A sheet of a photocurable adhesive composition impregnated with 0 μm glass cloth was obtained.

[0037]

[Table 1]

Example 2 A liquid photopolymerizable resin, a solid photopolymerizable resin, and a polymerization initiator shown in Table 2 were mixed in the mixing ratio shown in Table 2. This mixed composition was heated to 150 ° C. and sufficiently stirred, and then applied to a 100 μm-thick polyethylene terephthalate film to obtain a 300 μm-thick photocurable adhesive composition sheet. Further, the mixed composition was impregnated into a glass cloth having a thickness of 250 μm and a basis weight of 300 g / cm ² ,
A sheet of a photocurable adhesive composition impregnated with 0 μm glass cloth was obtained.

[0039]

[Table 2]

Comparative Example A liquid photopolymerizable resin, a gelling agent and a polymerization initiator shown in Table 3 were mixed in the mixing ratio shown in Table 3. After heating this mixed composition to 150 ° C. and stirring it sufficiently, a thickness of 100
μm polyethylene terephthalate film,
A sheet of a photocurable adhesive composition having a thickness of 300 μm was obtained. Further, the above-mentioned mixed composition was prepared with a thickness of 250 μm and a basis weight of 30.
Impregnated with 0 g / cm ² glass cloth, thickness 300 μm
The sheet of the photocurable adhesive composition impregnated with glass cloth was obtained.

[0041]

[Table 3]

Adherence to adherend : The sheet of the photocurable adhesive composition having a thickness of 300 μm without the glass cloth base material obtained in the above Examples 1 and 2 and Comparative Example was adhered to the adherend. Was evaluated. As the adherend, a transparent glass plate having a size of 100 mm × 100 mm and a polyethylene terephthalate (PET) film having a width of 5 mm and a thickness of 100 μm adhered at an interval of 5 mm (FIG. 1) was used. FIG. 1A is a plan view, and FIG.
(B) shows a side view.

The sheets of the photocurable adhesive composition without the glass cloth substrate of Examples 1 and 2 and Comparative Example were
After cutting to 0 mm x 100 mm, the P
Laminated on ET film surface, evenly 100g / cm
The adhesion area ratio (%) to the glass plate when a load of ² was applied was measured.

Evaluation of Initial Adhesiveness and Adhesive Strength Over Time The sheets of the photocurable adhesive compositions impregnated with glass cloth of Examples 1 and 2 and Comparative Example were evaluated for initial adhesiveness. Sandpaper ($ 2
80mm × 40mm SUS polished in 80)
A foil (thickness: 50 μm) was used.

After the sheets of Examples 1 and 2 and Comparative Example were cut into a size of 20 mm × 20 mm, the sheet 2 was attached to the polished surface 1a of the SUS foil 1 as shown in FIG. As shown in FIG. 3, ultraviolet rays having a wavelength of 365 nm are irradiated for 2 minutes at an intensity of 25 mW / cm ² , and then, as shown in FIG.
And a 2 kg pressure roller was reciprocated twice at a speed of 300 mm / min to obtain a T-peeling test piece.

Then, after standing in a thermo-hygrostat at 23 ° C. and 65% RH for 20 minutes, the tensile tester was used for 200 m.
A T-peel test was performed at a speed of m / min, and the maximum load was defined as the initial adhesive force.

After standing in a thermo-hygrostat at 23 ° C. and 65% RH for 48 hours, a T-peel test was conducted in the same manner, and the maximum load was defined as the adhesive force with time.

[0048]

[Table 4]

As is clear from Table 4, the sheets of the photocurable adhesive compositions of Examples 1 and 2 according to the present invention were more adherent than the sheets of the photocurable adhesive composition of the comparative example. It can be seen that the film has excellent followability, initial adhesive strength and temporal adhesive strength.

[0050]

The constitution of the photocurable adhesive composition of the present invention is as described above, and the photocured product has an appropriate cohesive force, and therefore has good wettability to an adherend. , And initial adhesion. Therefore, the photocurable adhesive composition of the present invention can be a sheet of the photocurable adhesive composition having good handling properties and good wettability to an adherend.

Further, by making the cationically polymerizable group of at least one of the liquid photopolymerizable resin and the solid photopolymerizable resin a photocationically polymerizable epoxy group,
The adhesive strength over time of the photocurable adhesive composition can be further improved.

[Brief description of the drawings]

FIG. 1 is a plan view (a) and a side view (b) for explaining a method of evaluating the ability to follow an adherend in an embodiment according to the present invention.

FIG. 2 is a perspective view for explaining a method for evaluating initial adhesion and temporal adhesion in an example according to the present invention.

FIG. 3 is a side view for explaining a method of evaluating initial adhesiveness and temporal adhesive strength in an example according to the present invention.

FIG. 4 is a side view for explaining a method for evaluating initial adhesiveness and temporal adhesive strength in an example according to the present invention.

[Description of Signs] 1,3: SUS foil 1a, 3a: Polished surface of SUS foil 2: Sheet of photocurable adhesive composition

Claims (2)

[Claims] (A) a compound having a cationically polymerizable group in the molecule and having a viscosity at 23 ° C. of 1 to 3 as measured by a B-type viscometer;
100 parts by weight of 0000 cps liquid photopolymerizable resin,
(B) having a cationically polymerizable group in the molecule and having a softening point of 4
A photocurable adhesive composition comprising 40 to 500 parts by weight of a solid photopolymerizable resin at 0 ° C to 200 ° C and (C) a cationic photopolymerization initiator. 2. The resin according to claim 1, wherein at least one of the liquid photopolymerizable resin (A) and the solid photopolymerizable resin (B) has a cationically polymerizable epoxy group. The photocurable adhesive composition according to claim 1, wherein