Adhesive for optical disks

Details Adhesive for optical disks Adhesive for optical disks

1999-07-20

2002-01-08

Evans, Elizabeth (Department: 1774)

Stock material or miscellaneous articles

Circular sheet or circular blank

C428S064400, C428S065200, C428S913000, C430S270110, C430S945000

Reexamination Certificate

active

06337118

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a photocurable adhesive for optical disks, and to optical disks made therewith.
BACKGROUND OF THE INVENTION
Recent progress of information technologies including computer devices, computer software, and communication technologies has allowed a high speed conveyance of mass information. Along with this advancement, recording media which can record much more information at high density have been desired and the development of such recording media is ongoing. An example of such high-density recording media is a DVD (digital video disk or digital versatile disk) which has been developed as a recording media for wide use in the next generation. The DVD differs from conventional CDs (compact disks) in that the DVD is manufactured by laminating two disks. Therefore, an adhesive for laminating these two disks is required. Hot-melt, heat-curable, anaerobic curable, and similar adhesives have been tried for laminating disks for DVD, but these adhesives have not been entirely successful. Hot-melt adhesives have insufficient heat stability and weatherability. Because the hot-melt adhesives soften at high temperature, the decreased adhesive strength causes the laminated disks to separate and deform. In addition, since transparency of the adhesive is insufficient, it is difficult to use hot-melt adhesives for the DVD with a two-layered structure comprising a translucent recording film. Heat-curable adhesives are unsatisfactory because heat curing causes the substrate for forming a disk to deform, and the curing time is long. Anaerobic curable adhesives are also unsatisfactory because they require a certain period of time for curing, thereby resulting in reduced productivity.
Photocurable adhesives have been proposed to solve these problems. For example, UV curable adhesives comprising a urethane acrylate as a major component has been disclosed in Japanese Patent Applications Laid-open No. 142545/1986 and No. 89462/1994.
However, UV curable adhesives known heretofore have also been unsatisfactory. Conventional UV curable adhesives do not provide sufficient adhesion to resins such as a polycarbonate for forming the disks, aluminum for forming reflecting films, gold for forming translucent films, and the like, while producing cured products with sufficient moisture resistance.
SUMMARY OF THE INVENTION
An object of the present invention therefore is to provide a UV curable adhesive which exhibits superior adhesion to resins, such as polycarbonate for forming the disks, aluminum for forming reflecting films, gold for forming translucent films, and the like. A related object is to provide a UV curable adhesive that can produce cured products with excellent moisture resistance, in particular at relatively high temperatures.
These and other objects and advantages of the invention will be readily understood by those skilled in the art in view of the detailed description of the preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
As a result of extensive studies, the inventors of the present invention have discovered that the above problems can be solved by the following adhesive for optical disks.
Specifically, in accordance with the present invention a photocurable adhesive for optical disks comprises the following components (A), (B), and (C):
(A) a urethane acrylate or methacrylate, referred to herein as (meth)acrylate comprising a backbone, urethane groups, and a (meth)acrylate group.
(B) a hydroxyalkyl (meth)acrylate, in which the hydroxyl group and the (meth)acrylate group are spaced apart by at least three (3) carbon atoms, and
(C) at least one photoinitiator. The adhesive composition of the present invention can also include at least one (meth)acrylate functional diluent (D) other than (B), and/or at least one non-(meth)acrylate functional diluent (E), as described more fully herein.
The urethane(meth)acrylate used as the component (A) is generally obtained by reacting a polyol, a polyisocyanate, and a hydroxyl group-containing (meth) acrylate.
The polyol that can be used to form the urethane (meth)acrylate can be a diol or a polyol. By way of illustration and not in limitation, the polyol can be a polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol, an aliphatic hydrocarbon containing two or more hydroxyl groups in the molecule, alicyclic hydrocarbon containing two or more hydroxyl groups in the molecule, unsaturated hydrocarbon containing two or more hydroxyl groups in the molecule, and the like. The polyols can be used either independently or in combinations of two or more.
The above polyether polyol includes aliphatic polyether polyols, alicyclic polyether polyols and aromatic polyether polyols.
Examples of aliphatic polyether polyols include polyhydric alcohols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, pentaerythritol, dipentaerythritol, trimethylolpropane, alkylene oxide addition polyols such as ethylene oxide addition triol of trimethylolpropane, propylene oxide addition triol of trimethylolpropane, ethylene oxide and propylene oxide addition triol of trimethylolpropane, ethylene oxide addition tetraol of pentaerythritol, ethylene oxide addition hexaol of dipentaerythritol, polyether polyols produced by ring-opening polymerization of two or more ionic polymerizable cyclic compounds, and the like.
Examples of the ionic polymerizable cyclic compounds include cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, 3,3-bischloromethyl oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl ether, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monoxide, isoprene monoxide, vinyloxetane, vinyltetrahydrofuran, vinylcyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidyl benzoate. Examples of specific combinations of two or more of the above ionic polymerizable cyclic compounds include combinations of tetrahydrofuran and ethylene oxide, tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3-methyltetrahydrofuran, ethylene oxide and propylene oxide, butene-1-oxide and ethylene oxide, and tetrahydrofuran, butene-1-oxide, and ethylene oxide.
A polyether polyol produced by ring-opening polymerization of one of the above ionic polymerizable cyclic compounds and cyclic imines such as ethyleneimine, cyclic lactic acids such as &bgr;-propyolactone and glycolic acid, or dimethylcyclopolysiloxane can also be used.
Examples of the alicyclic polyether polyols include alkylene oxide addition diol of hydrogenated bisphenol A, alkylene oxide addition diol of hydrogenated bisphenol F, and alkylene oxide addition diol of 1,4-cyclohexanediol.
Examples of the aromatic polyether polyols include alkylene oxide addition diol of bisphenol A, alkylene oxide addition diol of bisphenol F, alkylene oxide addition diol of hydroquinone, alkylene oxide addition diol of naphthohydroquinone, and alkylene oxide addition diol of anthrahydroquinone.
Polyether polyols are commercially available under the following trade names: examples of aliphatic polyether polyols include PTMG650, PTMG1000, PTMG2000 (manufactured by Mitsubishi Chemical Corp.), PPG1000, EXCENOL1020, EXCENOL2020, EXCENOL3020, EXCENOL4020 (manufactured by Asahi Glass Co., Ltd.), PEG1000, Unisafe DC1100, Unisafe DC1800, Unisafe DCB1100, Unisafe DCB1800 (manufactured by Nippon Oil and Fats Co., Ltd.), PPTG1000, PPTG2000, PPTG4000, PTG400, PTG650, PTG2000, PTG3000, PTGL1000, PTGL2000 (manufactured by Hodogaya Chemical Co., Ltd.), Z-3001-4, Z-3001-5, PBG2000, PBG2000B (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), TMP30, PNT4 Glycol, EDA P4, EDA P8 (manufactured by Nippon Nyukazai Co., Ltd.), and Quadrol (manufactured by Asahi Denka Kogyo K.K.); and examples of aromatic polyether polyols include Uniol DA400, DA700, DA

Affiliated with

Also associated with

Rating

Adhesive for optical disks does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Adhesive for optical disks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adhesive for optical disks will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2819948