JP2003147281A - Adhesive, method for adhering object to be adhered and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive exhibiting a high elongation and linear expansion coefficient and also a suitable elasticity after its curing. SOLUTION: The adhesive is provided by containing a polymerizable component consisting of a specific acrylic oligomer and acrylic monomer, and a rubber component, and exhibiting not only a high linear expansion coefficient, elongation and softness after its curing by the polymerizable component but also a high elasticity after the curing by the rubber component. Therefore, in the case of elevating a surrounding temperature of a laminated material 10 obtained by pasting the objectives to be pasted 11, 17 having different linear expansion coefficients each other through an adhesive layer 15, a stress generated in the adhesive layer 15 caused by the difference of the different expansion coefficients is absorbed by the flexibility of the adhesive layer 15 itself. Also, even if the adhesive layer 15 is deformed, since the adhesive layer 15 restores to its original shape by the elasticity of the adhesive layer 15 itself, the positional discrepancy of the objects to be adhered 15, 17 does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive, and more particularly to an adhesive for bonding glass parts and resin parts used in optical devices.

[0002]

2. Description of the Related Art Conventionally, glass has been used as a material for optical components such as various lenses, supporting members, and light receiving elements used in optical devices for optical pickups, and optical components are connected to each other. UV curable adhesives are widely used.

By the way, resins such as polymethylmethacrylate (hereinafter abbreviated as PMMA) and polycarbonate have been attracting attention as materials constituting each optical component. These resins are lighter than glass and easy to mold,
By using an optical component made of resin, it is possible to reduce the size and weight of the entire optical device, and the manufacturing cost is low.
Therefore, the material of the optical component is shifting from glass to resin, and under the present circumstances, an optical component made of glass and an optical component made of resin are often mixed in one optical device.

However, since the resin such as PMMA and the glass have different coefficients of thermal expansion, when the optical parts made of the resin and the optical parts made of the glass are bonded with an adhesive, the temperature around the optical device rises. In addition, the optical component may be peeled from the adhesive due to the stress caused by the difference in the expansion coefficient.

[0005]

The present invention was created in order to solve the above-mentioned disadvantages of the prior art, and is to provide an adhesive having a high coefficient of linear expansion and an appropriate elasticity. .

[0006]

In order to solve the above problems, the invention according to claim 1 contains a polymerizable component, a rubber component, and a photopolymerization initiator, and the polymerizable component is irradiated by ultraviolet rays. Is an adhesive configured to polymerize, wherein the polymerizable component contains an acrylic monomer and an acrylic oligomer, and the elongation percentage after polymerization of the polymerizable component by ultraviolet irradiation is 200% or more. It is an adhesive. The invention according to claim 2 is the adhesive according to claim 1, wherein the elongation percentage of the polymer obtained when the acrylic oligomer is homopolymerized is 150% or more. The invention according to claim 3 is claim 1 or claim 2.
The adhesive according to any one of items 1 to 5, wherein the amount of the rubber component added to 100 parts by weight of the polymerizable component is 0.5.
It is an adhesive which is more than part by weight. The invention according to claim 4 is the adhesive according to any one of claims 1 to 3, wherein the rubber component is a nitrile-butadiene rubber. The invention according to claim 5 is a method for connecting an object to be adhered, comprising: a first object to be adhered made of glass;
A step of closely adhering a second object to be adhered made of a resin through a coating layer made of the adhesive according to any one of claims 1 to 5, and irradiating the coating layer with ultraviolet rays,
And a step of curing an adhesive constituting the coating layer, which is a method for connecting objects to be attached. The invention according to claim 6 is an optical device, comprising: a first optical component made of glass;
A second optical component made of resin, wherein the first optical component and the second optical component are provided between the first optical component and the second optical component.
The optical device in which the adhesive according to any one of claims 1 to 3 is arranged, and the adhesive is cured by ultraviolet irradiation in a state where the adhesive is in close contact with both the first optical component and the second optical component. Is. According to a seventh aspect of the present invention, in the optical device according to the sixth aspect, the resin forming the second optical component is made of polymethylmethacrylate, polyethylene terephthalate, polycarbonate, and norbornene resin polymer. An optical device containing a resin selected from the group.

In the present invention, "acrylic monomer" means both acrylate and methacrylate,
"Acrylic oligomer" means a low polymer composed of one or both of acrylate and methacrylate.

The present invention is constituted as described above, and the elongation percentage of the entire adhesive after curing is 20 due to the acrylic oligomer and the acrylic monomer constituting the polymerizable component.
The flexibility is high at 0% or more. Further, the addition of rubber causes the adhesive after curing to have appropriate elasticity.

Therefore, when the adhesives of the present invention such as glass and resin are attached to each other with different expansion coefficients, the stress caused by the difference in expansion coefficient is
In addition to being relieved by the adhesive, the adhesive deformed by stress is restored by elasticity, so that the position of the adhered objects to be adhered does not shift.

Further, since the above-mentioned adhesive has high adhesiveness to resin and glass, it is difficult for the adhesive to peel off from the object to be attached. Various additives such as colorants can be added to the adhesive of the present invention. Further, the adhesive of the present invention has a high transparency of the cured product after curing in the state where the coloring agent is not added.

In the present invention, "elongation rate" means JIS K.
The "elongation at break" described in "Tensile Test" of 6251 was measured by the following method. Lamp output 120W for adhesives and oligomers that are objects of measurement
Illumination of 200 m using a metal halide lamp of / cm
The film-like cured product (having a film thickness of about 0. W / cm ² and an integrated light amount of 300 mJ / cm ² ) is irradiated with ultraviolet rays to be completely cured.
5 mm), it was punched out with a dumbbell No. 4 die to obtain a test piece.

[0012] Test specimens under the conditions described in "Tensile Test Methods" in JIS K6251, the distance between marked lines at the time of cutting is measured, marked lines before tensile from gauge length L ₁ at the time of cutting The distance L ₀ is subtracted, the distance between the marked lines before tension L ₀ is further divided, and the product of 100 is taken as the elongation rate ((L ₁ −L ₀ ) / L ₀ × 100, unit: %).

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing the adhesive of the present invention will be described below. First, an acrylic oligomer whose elongation rate of the polymer obtained by homopolymerization is 150% or more is prepared, and the acrylic oligomer and the acrylic monomer are mixed to obtain a polymerizable component.

Next, the photopolymerization initiator and the rubber component are added to the polymerizable component and mixed to prepare the adhesive of the present invention. This adhesive is liquid at room temperature under the condition that it is not irradiated with ultraviolet rays, and has high transparency to visible light and near infrared rays.

Next, a process of manufacturing the optical device of the present invention using the above adhesive will be described. Reference numeral 11 in FIG. 1A indicates a transparent first attachment target made of glass. The adhesive prepared in the above step is applied to the surface of the first object 11 to be adhered to form an adhesive coating layer 14 (FIG. 1B).

Next, a transparent second object to be adhered 17 made of a resin film is pressed against the coating layer 14 (FIG. 1).
(C)). In that state, ultraviolet rays are radiated toward the second object to be adhered 17, and the second object to be adhered 1 having a transparent ultraviolet ray.
When passing through 7 and reaching the coating layer 14, the polymerizable component of the adhesive forming the coating layer 14 is polymerized by ultraviolet rays and the adhesive is cured.

Reference numeral 15 in FIG. 1D shows an adhesive layer made of a cured adhesive, and the adhesive layer 15 bonds the first and second objects 11 and 17 to be attached to each other. . Reference numeral 10 in FIG. 1D indicates a laminated body in which first and second objects 11 and 17 to be adhered are adhered to each other.

Next, an example of an optical device using the adhesive of the present invention will be described. Reference numeral 20 in FIG. 2 indicates an example of the optical device. The optical device 20 has a first optical component 25, which is a glass lens, and a second optical component 27, which is a supporting member and is made of resin such as PMMA.

The first optical component 25 is shown in FIG.
In the step shown in (d), it is attached to the second optical component 27 via the adhesive layer 26, and the first optical component 25 is supported by the second optical component 27 so that Is held.

To read information on the optical recording medium 21 using the optical device 20, first, the laser irradiation device 2 is used.
The optical recording medium 22 is irradiated with the laser light 21 from 8. The laser light 21 reflected by the optical recording medium 22 enters the optical device 20 from the first optical component 25 of the optical device 20, and is detected by a light receiving element (not shown).

On the optical recording medium 22, the information is recorded as a pattern of concavities and convexities, and the intensity of the laser beam 21 reflected by the optical recording medium 22 changes depending on the pattern of concavities and convexities, so the reflected laser beam 21. The information on the optical recording medium 22 can be read by detecting the change in the intensity.

In the adhesive of the present invention, by mixing a specific acrylic oligomer and an acrylic monomer, the cured adhesive layer 26 has a high elongation rate of 200% or more, and has a different linear expansion coefficient. First and second optical components 2
Even when 5 and 27 are heated and expanded, the stress caused by the difference in expansion coefficient is absorbed and relaxed by the cured adhesive layer 26, so that the first and second optical components 25 and 27 are included.
Does not come off from the adhesive layer 26.

Further, since the adhesive layer 26 exhibits an appropriate elasticity due to the addition of the rubber component, even if the adhesive layer 26 is deformed due to external physical impact or temperature change, the adhesive layer 26 will be It recovers due to its elasticity.

Therefore, the first optical component 25 attached to the second optical component 27 via the adhesive layer 26 is always held at a predetermined position, so that the laser light incident from the first optical component 25 is incident. The focal length of 21 and the deviation of the image formation are prevented.

[0025]

[Examples] <Example 1> Acrylic oligomer (trade name "CN966J75" manufactured by Sartomer Co., Ltd.) having a polymer elongation rate of 150% or more when homopolymerized. 3
70 parts by weight of phenoxyethyl acrylate, which is an acrylic monomer, was added to and mixed with 0 part by weight to prepare a polymerizable component composed of an acrylic monomer and an acrylic oligomer. The acrylic oligomer used here was a low polymer of urethane acrylate, and the elongation percentage of the polymer obtained by homopolymerization was 238%.

Next, with respect to 100 parts by weight of the polymerizable component,
2 parts by weight of a nitrile butadiene rubber as a rubber component and a radical type photopolymerization initiator "IRGACURE 184" manufactured by Nagase Sangyo Co., Ltd. were added and mixed to obtain a liquid transparent Example 1. An adhesive was obtained.

<Examples 2 to 7> The same as Example 1 except that the addition amounts of the acrylic monomer and acrylic oligomer used in Example 1 and the addition amount of the rubber component were changed as shown in Table 1 below. The adhesives of Examples 2 to 7 were produced under the conditions.

[0028]

[Table 1]

<Comparative Example 1> An adhesive of Comparative Example 2 was prepared under the same conditions as in Examples 2 to 7 except that the rubber component was not added.

<Comparative Examples 2 and 3> As the acrylic oligomer, an acrylic oligomer (trade name "CN980" manufactured by Sartomer Co., Ltd.) whose elongation rate of the polymer obtained when homopolymerized is less than 150% is used. , Table 1 above
The adhesives of Comparative Examples 2 and 3 were prepared with the compounding ratios described in 1. The acrylic oligomers used in Comparative Examples 2 and 3 are
It was a low polymer of urethane acrylate, and the elongation percentage of the polymer obtained by homopolymerization was 63%.
Using the adhesives of Examples 1 to 7 and Comparative Examples 1 to 3, the following "linear expansion coefficient", "elasticity", "reliability test",
"Elongation rate" Each evaluation test was performed.

[Elongation rate] The adhesives of Examples 1 to 7 and Comparative Examples 1 to 3 were applied on release paper to form a coating layer, and a metal halide lamp with a lamp output of 120 W / cm was used to obtain an illuminance of 200 mW / cm. ^2. After curing by irradiating with ultraviolet rays having an integrated light quantity of 300 mJ / cm ² , the cured adhesive was peeled from the release paper, and 10 kinds of film-shaped test pieces were prepared. Using these 10 kinds of test pieces, the elongation rate of the test piece was measured according to the method of "tensile test" of JIS K6251 as described above, and the obtained elongation rates (%) are shown in Table 1 above. did.

[Linear Expansion Coefficient] Ten kinds of test pieces were prepared in the same process as the above-mentioned “elongation rate” test, and the initial length L was measured in a state where a predetermined load was applied to the test pieces, followed by measurement. The temperature of the atmosphere was increased from 25 ° C. to 85 ° C., and the length increase dL due to the temperature increase of the test piece was measured. The increase amount dL of the length, the change amount dT of the temperature, and the initial length L of the sample piece are applied to the following equation (1) to obtain the linear expansion coefficient b.
I asked. Formula (1): b = (dL / dT) / L The obtained linear expansion coefficient (× 10 ⁻⁵ / K) is shown in Table 1 above.

[Return Rate] A cooling treatment for cooling to -40 ° C. and a heating treatment for raising the temperature to 85 ° C. are repeatedly performed on the test piece prepared in the “linear expansion coefficient” test under a load of 1 g. The lengths at −40 ° C. and 85 ° C. were measured. The temperature in the initial state was room temperature of 25 ° C., and the cooling treatment was performed first.

During the first cooling treatment (from 25 ° C.
Length P ₁ of the test piece (when cooled to 40 ° C.) and lengths P ₂ and P ₃ of the test piece of the _second and _third cooling treatments (when cooled from 85 ° C. to −40 ° C.) And the first and second
The length Q ₁ and Q ₂ of the test piece at the time of the second heat treatment (when heated from −40 ° C. to 85 ° C.) were measured, and the low temperature return rate R ₁ and R ₂ (%) and the high temperature return The rate S ₁ (%) is calculated by the following formula: R ₁ = (P ₂ −P ₁ ) / P ₁ × 100 R ₂ = (P ₃ −P ₁ ) / P ₁ × 100 S ₁ = (Q ₂ −Q ₁ ) / Q ₁ × 100. The total time required for one heat treatment and one cooling treatment was 30 minutes. The lower the return rate value, the higher the elasticity of the sample piece.

[Reliability Test] A coating layer 1 was prepared by applying the ten kinds of adhesives of Examples 1 to 7 and Comparative Examples 1 to 3 to the first object to be adhered 11 made of white plate glass by spin coating.
4 is formed and a PMMA resin film which is the second object to be adhered 17 is brought into close contact with the coating layer 14, and then the laminated body 10 is irradiated with ultraviolet rays under the same irradiation conditions as in the "elongation rate" test.
10 kinds of test pieces consisting of These 10 kinds of test pieces were observed while repeating the cooling treatment and the heating treatment under the same conditions as the "return rate".

"NG" indicates that peeling or cracks of the adhesive layer 15 were observed in the heating and cooling treatment for less than 400 hours, and "OK" indicates that the appearance did not change after 400 hours. evaluated. The evaluation results and the time when the appearance change was confirmed are shown in Table 1 above.

As is clear from Table 1, Examples 1 to 7 of the present invention have an elongation after curing of 200% or more, a large linear expansion coefficient, and sufficient flexibility. I understand. In addition, in Examples 1 to 7, the return rate was sufficiently low, and it can be seen that the adhesive after curing has sufficient elasticity. Further, as is clear from the results of the reliability test, the adhesives of Examples 1 to 7 having both flexibility and elasticity have higher durability due to temperature change than Comparative Examples 1 to 3.

Among these, the addition amount of the rubber component is 0.
Examples 1 to 6, which are 5 parts by weight or more and 15 parts by weight or less, have a lower return rate than Example 7 in which the amount of the rubber component added is 0.1 parts by weight, and high results are obtained in the reliability test. Was given. On the other hand, in the case of Comparative Example 1 containing the same polymerizable component as in Examples 2 to 7 but not containing the rubber component, the results of the coefficient of linear expansion and the elongation were similar to those of Examples 1 to 7, The return rate at each temperature was high.

Further, in Comparative Examples 2 and 3 in which the elongation percentage of the polymer containing a rubber component but obtained by homopolymerization of the acrylic oligomer was less than 150%, the value of the return rate in the elasticity test was measured. Although as low as Examples 1-7,
The values of linear expansion coefficient and elongation were low. In Comparative Examples 1 to 3 in which either the flexibility indicated by the coefficient of linear expansion or the elasticity indicated by the return rate is not sufficient, the result of the reliability test is also poor, and in Comparative Example 1, the adhesive layer formed in 200 hours. Peeling was observed, and in Comparative Examples 2 and 3, cracks were observed in the adhesive layer after 100 hours.

The same as Comparative Examples 2 and 3 except that an acrylic oligomer (trade name "CN981" manufactured by Sartomer Co., Ltd.) whose elongation rate of the polymer obtained by homopolymerization was 81% was used. When a test piece was prepared under the conditions,
Similar to Comparative Examples 2 and 3, the values of linear expansion coefficient and elongation were low.

From these facts, the adhesive of the present invention has a high elongation and a linear expansion coefficient after curing by using a specific polymerizable component, and has an appropriate elasticity after curing by adding a rubber component. As a result, it was confirmed that the reliability was high.

Although the case where phenoxyethyl acrylate is used as the acrylic monomer has been described above, the present invention is not limited to this, and for example,
Various acrylates such as tetrahydrofurfuryl acrylate can be used, and these acrylates may be used alone or as a mixture of two or more kinds.

Further, the acrylic oligomer is not limited to the urethane acrylate low polymer, and if the elongation of the polymer obtained by homopolymerization is 150% or more, ester acrylate, epoxy acrylate, melamine acrylate. Various low-polymers of acrylate can be used. Also, the photopolymerization initiator is not particularly limited.

Although the case where nitrile butadiene rubber is used as the rubber component has been described above, other than nitrile butadiene rubber, for example, natural rubber, isopropylene rubber, butadiene rubber, 1,2 polybutadiene rubber,
Various rubbers such as styrene-butadiene rubber, chloroprene rubber and butyl rubber can be used. These rubber components may be used alone or as a mixture of two or more kinds.

The material forming the object to which the adhesive is applied is not limited to glass or resin. The resin constituting the object to be attached is not limited to PMMA, and various resins such as polyethylene terephthalate, polycarbonate, norbornene resin polymer, triacetyl cellulose, polyolefin and polypropylene can be used.

The method of irradiating ultraviolet rays is not particularly limited, and if an object to be adhered which transmits ultraviolet rays is used, the object to be adhered is irradiated with ultraviolet rays to reach the adhesive. be able to. Also, the irradiation conditions of ultraviolet rays are not particularly limited, but when the irradiation amount of ultraviolet rays becomes too large, the polymerizable component and the rubber component are excessively polymerized and the elastic modulus is lost, so that the illuminance is 5 mW / cm. ² or more and 1000 mW / cm ² or less, and the accumulated light amount is 3
MJ / cm ² or more 5000 mJ / cm ² or less is preferably.

The case where the lenses, which are the optical components 25 and 27, and the support member are bonded together has been described above.
The present invention is not limited to this, and can be used, for example, for bonding a plurality of lenses made of different materials and bonding various optical components such as a light receiving element and a hologram film.

The object to be stuck is not limited to an optical component, and according to the connection method of the present invention, for example, a liquid crystal panel used in a liquid crystal display device and a polarizing plate are stuck together, or a resin film is used. And a glass plate can be attached. For example, a resin film having flexibility,
When laminated with a glass plate, a composite glass plate having excellent impact resistance can be obtained.

[0049]

EFFECTS OF THE INVENTION According to the present invention, since the adhesive has a high coefficient of expansion and a linear expansion coefficient after being cured, and has an appropriate elasticity, the objects to be adhered having different thermal expansion coefficients are bonded together. Even if it does, the adhesive does not peel off, and the position of the object to be attached does not easily shift.

[Brief description of drawings]

1A to 1D are cross-sectional views for explaining a step of attaching objects to be attached using the adhesive of the present invention.

FIG. 2 is a diagram for explaining an example of an optical device of the present invention.

[Explanation of symbols]

10 ... Optical device 14 ... Adhesive (adhesive coating layer) 15, 26 ... Adhesive layer (cured adhesive) 11 ... First object to be attached 17: Second object to be attached 20 ... Optical device 25: First optical component 27 ... Second optical component

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 3/00 G02B 3/00 Z 7/00 7/00 FF term (reference) 2H043 AE02 4J011 AA05 AC04 PA76 PC02 PC08 4J026 AA68 AC12 AC32 BA27 BA50 BB03 BB10 DB36 GA08 4J040 CA032 CA072 FA131 MA05 MA10 PA32

Claims (7)

[Claims] 1. An adhesive comprising a polymerizable component, a rubber component, and a photopolymerization initiator, wherein the polymerizable component is polymerized by irradiation of ultraviolet rays, wherein the polymerizable component is acrylic. An adhesive containing a monomer and an acrylic oligomer and having an elongation percentage of 200% or more after the polymerizable component is polymerized by irradiation with ultraviolet rays. 2. The adhesive according to claim 1, wherein the elongation percentage of the polymer obtained by homopolymerizing the acrylic oligomer is 150% or more. 3. The amount of the rubber component added to 100 parts by weight of the polymerizable component is 0.5 parts by weight or more.
Alternatively, the adhesive according to claim 2. 4. The adhesive according to claim 1, wherein the rubber component is nitrile butadiene rubber. 5. The first object to be adhered, which is made of glass, and the second object to be adhered, which is made of resin, according to any one of claims 1 to 5.
An object to be attached, which comprises a step of bringing the adhesive layer into close contact with the adhesive layer through the coating layer, and a step of irradiating the coating layer with ultraviolet rays to cure the adhesive forming the coating layer. How to connect. 6. A first optical component made of glass and a second optical component made of resin, wherein the first optical component and the second optical component are provided between the first optical component and the second optical component. Item 5. The adhesive according to any one of items 5 is arranged, and the adhesive is cured by ultraviolet irradiation while the adhesive is in close contact with both the first optical component and the second optical component. Optical device. 7. The resin constituting the second optical component contains a resin selected from the group consisting of polymethylmethacrylate, polyethylene terephthalate, polycarbonate, and norbornene resin polymer. Optical device.