JP3965511B2 - Epoxy resin adhesive for optical disc bonding - Google Patents

Description

前記式中、ｍ及びｎは平均重合度を示し、ｍは０より多く１０以下の数、好ましくは１〜３の数を示し、ｎは０より多く１０以下の数、好ましくは１〜３の数を示す。
なお、本発明では、このエポキシ樹脂Ａに他の各種エピービス型エポキシ樹脂（エポキシ樹脂Ｂ）を混合して使用することも可能である。このエポキシ樹脂Ｂには、ビスフェノールＡ型、ビスフェノールＦ型、ビスフェノールＡＤ型等のエポキシ樹脂を使用することができる。
エポキシ樹脂Ａの添加量は、全エポキシ樹脂の５０重量％以上が望ましく、それより少ないと、十分な接着強度や可トウ性が得られなくなる。
【０００６】
本発明の接着剤は、前記エポキシ樹脂の他、カチオン重合用触媒及びイオン吸着体を含有する。
カチオン重合用触媒としては、従来公知の各種のものが使用される。この触媒には、紫外線等のエネルギー線を照射すると、ルイス酸を発生するものが包含される。このようなものとしては、芳香族ジアゾニウム塩、芳香族スルホニウム塩、芳香族ヨードニウム塩、芳香族セリニウム塩等が挙げられる。カチオン重合用触媒の使用割合は、前記混合エポキシ樹脂１００重量部当り、１〜６重量部、好ましくは０．５〜６重量部の割合である。
【０００７】
イオン吸着体は、エネルギー線を照射したときに、カチオン重合用触媒から発生するルイス酸等のアニオン性物質を吸着するもので、従来公知の各種のものを用いることができる。このイオン吸着体としては、通常、イオン交換樹脂、例えば、アンバーライトＣＧ１２０（オルガノ社）、トミックスＡＤ５００、６００（富田製薬社）、キョーワード５００、６００（協和化学社）、ＩＸＥ−５００、７００、６００、１１００（東亜合成社）等が挙げられる。このアニオン吸着剤は、カチオン重合用触媒１重量部当り、２〜１２重量部、好ましくは４〜８重量部の割合である。このイオン吸着体は、触媒から放出されたルイス酸アニオンを吸着し、そのルイス酸アニオンによる腐食作用等を制止する。
【０００８】
本発明の接着剤には、脂肪族ポリオールを配合することが好ましい。このようなものとしては、例えば、エチレングリコール、プロピレングリコール、ポリエチレングリコール、ポリプロピレングリコール、ブチレングリコール等の（ポリ）アルキレングリコールの他、グリセリン、ポリグリセリン、ペンタエリスリトール、ポリカプロラクトンポリオール等が挙げられる。
この脂肪族ポリオールは、可とう性付与や、室温熟成時間後の反応の完結性を高める等の効果を与えるもので、その配合量は、混合エポキシ樹脂１００重量部当り、５〜５０重量部、好ましくは１０〜３０重量部の割合である。
【０００９】
本発明の接着剤には、必要に応じ他の成分、例えば、充填剤や、カップリング剤、消泡剤、界面活性剤等の慣用の添加成分を配合することができる。
【００１０】
本発明の接着剤は、前記した各成分を均一に混合することにより得ることができる。
【００１１】
本発明の接着剤は、エネルギー線（紫外線や電子線等）の照射により硬化反応を開始するもので、その硬化反応は迅速に進み、室温において、１分以内に接着強度が出現し、通常、２〜５時間で完全硬化する。
【００１２】
本発明の接着剤は、張り合せ型光ディスクを製造する場合の接着剤として有利に用いられる。本発明の接着剤を用いて貼り合せ型光ディスクを製造するには、２つのディスクの貼り合せ面に接着剤を塗布し、接着剤層を形成する。この接着剤層の厚さは、通常１０〜６０μｍである。この接着剤層は、１つの光ディスク又は２つの光ディスクの接着面に形成することができる。次に、この接着剤層にエネルギー線を照射し、エポキシ樹脂のカチオン重合（硬化反応）を開始させる。このエネルギー線照射後、両者の光ディスクを貼り合せ、圧着固化する。このようにして貼り合せ型光ディスク（光情報記録媒体）を得ることができる。
本発明の接着剤を用いて貼り合せ型光ディスクを製造するときには、その接着剤の硬化反応速度が速く、短時間でその完全硬化が終了することから、反りの問題等の不都合を生じない。
【００１３】
【実施例】
次に、本発明を実施例によりさらに詳細に説明する。
【００１４】
実施例１
表１に示す成分組成（重合部）の接着剤を調製し、その性能を評価した。その結果を表１に示す。
なお、表１に示した接着剤成分の具体的内容は以下の通りである。
（１）エポキシ樹脂Ａ
前記一般式（１）において、ｍが約１、ｎが約１のエポキシ樹脂、エポキシ当量：３３０
（２）エポキシ樹脂Ｂ
下記一般式（２）において、ｎが０．２のエポキシ樹脂、エポキシ当量：１９０
【化２】

【００１５】
（３）脂環式エポキシ樹脂Ａ
下記式で表されるエポキシ樹脂
【化３】

（４）脂環式エポキシ樹脂Ｂ
【化４】

但し、Ｒは次式で表される脂肪族基である。
【化５】

（５）水添ＢｉｓＡエポキシ樹脂
下記式で表されるエポキシ樹脂
【化６】

（６）ポリオール
ε−カプロラクトントリオール（水酸基当量：約３００）
【００１６】
また、表１に示した硬化性の評価は以下のようにして行った。
ポリカーボネート製ディスクに、２０〜３０μｍの厚みで接着剤を塗布し、高圧水銀ランプ（１５０Ｗ／ｃｍ）にて、７秒間紫外線を照射し、別のディスクを貼り合わせ、接着強度の出現するまでの時間を測定した。
前記硬化性の評価基準は以下の通りである。
○：接着強度出現時間：２０〜６０秒
×：接着強度出現時間：２０秒以下又は６０秒以上
（７）カチオン重合用触媒
ユニオンガベイド社製、サイラキャア ＵＶＩ ６９７４
（８）イオン吸着体
東亜合成社製、ＩＸＥ６００
【００１７】
表１に示した剥離接着強度（Ｎ／ｃｍ）は、以下のようにして測定したものである。
光ディスク用ポリカーボネート材を扇状に１６分割し、テストピースとした。これに接着剤を約５ｍｍ直径の円になるように塗布し、紫外線を照射した後貼り合わせ、この接着試験片にて、インストロン万能試験機を用い３点曲げ試験を用い、接着層がはがれたときの強度（Ｎ）を直径（ｃｍ）で除した値を剥離接着強度とした。
【００１８】
表１に示した初期のＴｇは、以下のようにして測定されたものである。
接着剤を紫外線硬化させた後、厚み０．２×長さ４０×幅７ｍｍの短冊状に成形し、室温に２４時間放置した後に、セイコー電子工業製ＤＭＳ１１０にて動的粘弾性を測定し、ｔａｎδピークをＴｇ点とした。
【００１９】
表１に示した高温高湿放置後のＴｇは、以下のようにして測定されたものである。
上記で作成した短冊状成形物を８５℃／８５％ＲＨの高温高湿槽に９６時間（ｈ）入れた後、同様の測定を行った。
【００２０】
表１に示した落下衝撃試験は、以下のようにして測定されたものである。
アルミ蒸着層などのついた光ディスクを接着剤で貼り合わせた後、高さ２ｍよりコンクリート地面に落下させ、接着層の剥離や記録層、反射膜の破壊状態を顕微鏡で観察した。その評価基準は以下の通りである。
○：接着層の剥離及び記録層、反射膜の破壊全くなし
△：記録層、反射膜の破壊は見られないが、接着層の剥離が見られる
×：接着層の剥離及び記録層、反射層の破壊が著しく見られる
【００２１】
【表１】

【００２２】
前記配合物Ｎｏ．１は、初期Ｔｇが９５℃と高すぎ、かつ剥離接着強度が７Ｎ／ｃｍと低い為、落下衝撃試験により、接着層剥離及び記録層の破壊が観察された。
前記配合物Ｎｏ．２は、反応が速すぎて、貼り合わせた不可能であった。
前記配合物Ｎｏ．３は、Ｔｇは低いが、剥離接着強度が著しく低い為、落下衝撃試験にて接着層剥離が発生し、また高温高湿放置後にＴｇの上昇が見られた。
Ｎｏ．４もＮｏ．１と同様にＴｇが高い為、落下衝撃試験により、接着層剥離及び記録層の破壊が観察された。
Ｎｏ．５〜７はいずれも良好な剥離接着性を示し、またＴｇが低く可とう性を有する為、落下衝撃試験にて良好な結果を示し、かつ高温高湿放置後のＴｇの上昇が少なかった。
【００２３】
【発明の効果】
本発明によれば、良好な接着性及び落下衝撃性を持つ光ディスクを製造することができ、しかも高温高湿など環境試験放置後にもＴｇの変化が極めて少なく、実質的な反りを防止でき、接着層にしわなどの変化が発生しない。
本発明の接着剤は、貼り合せ型光ディスクの製造用接着剤として有利に用いることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin adhesive for laminating optical disks.
[0002]
[Prior art]
In order to bond the optical disks, a cationically polymerizable epoxy resin adhesive layer is formed on the bonding surface of the two disks, and the surface of the adhesive layer is irradiated with UV (ultraviolet rays), and then the bonding method is used. An adhesive using a certain kind of aliphatic cyclic epoxy resin and bisphenol type epoxy resin (Japanese Patent Laid-Open No. 9-249734) is known.
However, since the adhesive used here has low adhesion to the disk material and the adhesive layer is hard and brittle, problems such as peeling of the adhesive interface and destruction of the recording layer occur when the disk drop impact test is performed.
In addition, the reaction does not finish completely during room temperature aging after bonding, and when the bonded disk is subjected to an environmental test such as high temperature and high humidity, the reaction of the adhesive further proceeds, and the Tg and elastic modulus of the adhesive May change, causing problems such as disk warping and wrinkling of the adhesive layer.
Furthermore, for optical disc bonding using the same type of adhesive, a method is known to prevent the adhesive from sticking out at the time of bonding by irradiating the end surface with infrared rays after irradiating the entire surface of the adhesive with ultraviolet rays. However, such infrared processing is cumbersome and not preferable.
[0003]
[Problems to be solved by the invention]
The present invention is a cationically polymerizable epoxy resin adhesive that starts polymerization by irradiation of energy rays such as ultraviolet rays, has excellent adhesion to the disk material and is flexible, and after ultraviolet light irradiation and pasting It is an object of the present invention to provide an adhesive in which the reaction rate quickly reaches a saturation point during aging at room temperature and the mechanical properties of the adhesive change very little during an environmental test.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, according to the present invention, in an epoxy resin adhesive for laminating optical disks, an adhesive for laminating optical disks comprising (i) polyoxyalkylene diglycidyl ether, (ii) a catalyst for cationic polymerization, and (iii) an ion adsorbent. Is provided.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The epoxy resin used in the present invention is composed of polyoxyalkylene diglycidyl ether (epoxy resin A) or a mixture of this and various epibis epoxy resins (epoxy resin B). The epoxy resin A is represented by the following general formula (1).
[Chemical 1]

In the above formula, m and n represent the average degree of polymerization, m represents a number greater than 0 and 10 or less, preferably 1 to 3, and n represents a number greater than 0 and 10 or less, preferably 1 to 3. Indicates a number.
In the present invention, the epoxy resin A can be mixed with other various Epbis epoxy resins (epoxy resin B). As the epoxy resin B, epoxy resins such as bisphenol A type, bisphenol F type, and bisphenol AD type can be used.
The addition amount of the epoxy resin A is desirably 50% by weight or more of the total epoxy resin, and if it is less than that, sufficient adhesive strength and towability cannot be obtained.
[0006]
The adhesive of the present invention contains a cationic polymerization catalyst and an ion adsorber in addition to the epoxy resin.
Various conventionally known catalysts are used as the catalyst for cationic polymerization. The catalyst includes a catalyst that generates a Lewis acid when irradiated with energy rays such as ultraviolet rays. Examples of such compounds include aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, aromatic sericium salts, and the like. The proportion of the cationic polymerization catalyst used is 1 to 6 parts by weight, preferably 0.5 to 6 parts by weight per 100 parts by weight of the mixed epoxy resin.
[0007]
The ion adsorbent adsorbs anionic substances such as Lewis acid generated from the catalyst for cationic polymerization when irradiated with energy rays, and various conventionally known ones can be used. As this ion adsorbent, ion exchange resins such as Amberlite CG120 (organo), Tomix AD500, 600 (Tonda Pharmaceutical), Kyoward 500, 600 (Kyowa Chemical), IXE-500, 700, 600, 1100 (Toa Gosei Co., Ltd.) and the like. This anion adsorbent is in a ratio of 2 to 12 parts by weight, preferably 4 to 8 parts by weight, per 1 part by weight of the catalyst for cationic polymerization. This ion adsorbent adsorbs the Lewis acid anion released from the catalyst, and inhibits the corrosive action and the like by the Lewis acid anion.
[0008]
The adhesive of the present invention preferably contains an aliphatic polyol. Examples of such materials include (poly) alkylene glycols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, and butylene glycol, as well as glycerin, polyglycerin, pentaerythritol, polycaprolactone polyol, and the like.
This aliphatic polyol gives effects such as imparting flexibility and enhancing the completeness of the reaction after room temperature aging time, and its blending amount is 5 to 50 parts by weight per 100 parts by weight of the mixed epoxy resin, The ratio is preferably 10 to 30 parts by weight.
[0009]
In the adhesive of the present invention, other components, for example, conventional additive components such as a filler, a coupling agent, an antifoaming agent, and a surfactant can be blended as necessary.
[0010]
The adhesive of the present invention can be obtained by uniformly mixing the above-described components.
[0011]
The adhesive of the present invention starts a curing reaction by irradiation with energy rays (such as ultraviolet rays and electron beams), the curing reaction proceeds rapidly, and an adhesive strength appears within 1 minute at room temperature. Complete cure in 2-5 hours.
[0012]
The adhesive of the present invention is advantageously used as an adhesive in the production of a laminated optical disk. In order to manufacture a bonded optical disk using the adhesive of the present invention, an adhesive is applied to the bonded surfaces of two disks to form an adhesive layer. The thickness of this adhesive layer is usually 10 to 60 μm. This adhesive layer can be formed on the adhesive surface of one optical disk or two optical disks. Next, the adhesive layer is irradiated with energy rays to initiate cationic polymerization (curing reaction) of the epoxy resin. After this energy beam irradiation, both optical discs are bonded together and pressure-bonded and solidified. In this way, a bonded optical disk (optical information recording medium) can be obtained.
When a bonded optical disk is manufactured using the adhesive of the present invention, the curing reaction rate of the adhesive is fast and the complete curing is completed in a short time, so that there is no inconvenience such as a warp problem.
[0013]
【Example】
Next, the present invention will be described in more detail with reference to examples.
[0014]
Example 1
Adhesives having the component composition (polymerization part) shown in Table 1 were prepared and their performance was evaluated. The results are shown in Table 1.
The specific contents of the adhesive components shown in Table 1 are as follows.
(1) Epoxy resin A
In the general formula (1), m is about 1 and n is about 1 epoxy resin, epoxy equivalent: 330
(2) Epoxy resin B
In the following general formula (2), n is 0.2 epoxy resin, epoxy equivalent: 190
[Chemical formula 2]

[0015]
(3) Alicyclic epoxy resin A
Epoxy resin represented by the following formula

(4) Alicyclic epoxy resin B
[Formula 4]

However, R is an aliphatic group represented by the following formula.
[Chemical formula 5]

(5) Hydrogenated BisA epoxy resin Epoxy resin represented by the following formula:

(6) Polyol ε-caprolactone triol (hydroxyl equivalent: about 300)
[0016]
The evaluation of curability shown in Table 1 was performed as follows.
Adhesive is applied to a polycarbonate disk with a thickness of 20 to 30 μm, irradiated with ultraviolet light for 7 seconds with a high-pressure mercury lamp (150 W / cm), another disk is bonded, and the time until the adhesive strength appears Was measured.
The evaluation criteria for the curability are as follows.
○: Adhesive strength appearance time: 20 to 60 seconds ×: Adhesive strength appearance time: 20 seconds or less or 60 seconds or more (7) Cationic polymerization catalyst manufactured by Union Gavail Co., Ltd., Silacair UVI 6974
(8) IXE600 manufactured by Toa Gosei Co., Ltd.
[0017]
The peel adhesion strength (N / cm) shown in Table 1 is measured as follows.
A polycarbonate material for optical discs was divided into 16 fan shapes to form test pieces. Adhesive is applied to this to form a circle with a diameter of about 5 mm, and after being irradiated with ultraviolet rays, the adhesive layer is peeled off using a three-point bending test using an Instron universal testing machine. The value obtained by dividing the strength (N) by the diameter (cm) was defined as the peel adhesive strength.
[0018]
The initial Tg shown in Table 1 was measured as follows.
After the adhesive was cured with ultraviolet rays, it was shaped into a strip of thickness 0.2 × length 40 × width 7 mm, and allowed to stand at room temperature for 24 hours, and then measured for dynamic viscoelasticity with DMS110 manufactured by Seiko Electronics Industry, The tan δ peak was taken as the Tg point.
[0019]
The Tg after standing at high temperature and high humidity shown in Table 1 was measured as follows.
The strip-shaped molded product prepared above was placed in a high-temperature and high-humidity tank at 85 ° C./85% RH for 96 hours (h), and then the same measurement was performed.
[0020]
The drop impact test shown in Table 1 was measured as follows.
After an optical disk with an aluminum vapor deposition layer and the like was bonded together with an adhesive, it was dropped onto the concrete ground from a height of 2 m, and the peeling of the adhesive layer and the destruction state of the recording layer and the reflective film were observed with a microscope. The evaluation criteria are as follows.
◯: No peeling of the adhesive layer and no destruction of the recording layer and the reflective film Δ: No destruction of the recording layer and the reflective film is observed, but peeling of the adhesive layer is observed x: Peeling of the adhesive layer and the recording layer, the reflective layer [0021]
[Table 1]

[0022]
Said formulation No. In No. 1, since the initial Tg was too high at 95 ° C. and the peel adhesive strength was as low as 7 N / cm, peeling of the adhesive layer and destruction of the recording layer were observed by a drop impact test.
Said formulation No. In No. 2, the reaction was too fast to be pasted together.
Said formulation No. No. 3 had a low Tg, but the peel strength was remarkably low, so that peeling of the adhesive layer occurred in the drop impact test, and an increase in Tg was observed after standing at high temperature and high humidity.
No. No. 4 is also No.4. Since Tg was high as in Example 1, peeling of the adhesive layer and destruction of the recording layer were observed by a drop impact test.
No. All of Nos. 5 to 7 showed good peel adhesion, had low Tg and had flexibility, showed good results in a drop impact test, and had little increase in Tg after being left at high temperature and high humidity.
[0023]
【The invention's effect】
According to the present invention, it is possible to produce an optical disk having good adhesion and drop impact, and there is very little change in Tg even after leaving an environmental test such as high temperature and high humidity. No changes such as wrinkles occur in the layer.
The adhesive of the present invention can be advantageously used as an adhesive for producing a bonded optical disk.

Claims (3)

An optical disk laminating adhesive comprising: (i) a polyoxyalkylene diglycidyl ether, (ii) a cation polymerization catalyst, and (iii) an ion adsorbent. The adhesive of claim 1 containing an aliphatic polyol. The adhesive of Claim 1 or 2 containing another epoxy resin.