Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-10-18
2002-05-07
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S270100
Reexamination Certificate
active
06383716
ABSTRACT:
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP99/00741 which has an International filing date of Feb. 19, 1999, which designated the United States of America.
TECHNICAL FIELD
The present invention relates to a photosensitive resin composition, more particularly to a photosensitive resin composition which is thermally stable, causes no improper development or discoloration with the lapse of time, and has excellent storage stability.
BACKGROUND ART
“Photosensitive resin” referred to in the present invention is such a resin that a photopolymerization initiator contained therein generates a radical on receiving energy such as light or electron beam, allowing a radical crosslinking reaction to take place and selectively proceed at the light-irradiated portion to cause a change of solubility or dispersibility of the resin in solvents or a change of mechanical strength of the resin.
These resins generally contain an unsaturated compound and a photopolymerization initiator and are converted to polymeric resins after polymerization. In actual use of such resins, by taking advantage of the above property, the light-irradiated portion and the non-irradiated portion are treated with a developing solution (generally a solvent or an aqueous surfactant-containing solution) to remove the non-polymerized portion. (This treatment is hereinafter called development.)
These resins are thermally unstable because of their high reactivity. For instance, in case an article containing this type of resin is produced by a process requiring a high-temperature treatment, or is kept in storage for a long time, a radical crosslinking reaction takes place and proceeds in the resin throughout, even at the portion where it is desired to selectively prevent the polymerization from taking place, making it unable to perform normal development. In order to avoid such unfavorable phenomenon, various ideas have been proposed, such as lowering the treating temperature in the process or lowering the storage temperature. It has also been attempted to add a heat stabilizer to the resin to thereby maintain stability.
For instance, JP-A-62-95310 proposes use of hindered phenols (sterically hindered monophenols) or their thio-compounds.
However, the stabilizers which have so far been disclosed to be used for photosensitive resins and the like are unsatisfactory in their thermal stabilization effect. Some of those stabilizers are raised in their effect as their content is increased, but such stabilizers, in use, are reduced in sensitivity and prone to become substantially unserviceable, and are also subject to restrictions in relation to the process or compounding with the photosensitive resin.
It is also common practice to further contain a thermoplastic elastomer in a stabilizer-containing photosensitive resin composition for improving handling qualities of the composition. However, incorporation of a thermoplastic elastomer, which in itself is high in molecular weight, is liable to cause improper development.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a photosensitive resin composition having high photopolymerization reactivity and thermal stability.
As a result of extensive studies for solving said problems in the prior art, the present inventors found that use of bis(3,5-di-t-butyl-4-hydroxybenzyl) sulfide (hereinafter referred to as BBHS in some cases) as a stabilizer produces a surprising stabilizing effect specifically for photosensitive resins, and further, additional use of 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-alkylphenyl acrylate (hereinafter referred to as BBHMAA in some cases) in combination with BBHS provides further improvement of the stabilizing effect, and that especially in a system containing a thermoplastic elastomer, the composition is made even more stable by containing a specific phosphorus compound in the composition. The present invention has been attained on the basis of the above finding.
Thus, the present invention provides:
(1) A photosensitive resin composition containing bis(3,5-di-t-butyl-4-hydoxybenzyl) sulfide.
(2) A photosensitive resin composition described in (1) above, also containing 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-alkylphenyl acrylate.
(3) A photosensitive resin composition described in (1) or (2) above, further containing a thermoplastic elastomer and at least one phosphorus compound selected from the group consisting of monoisodecyl phosphate, monomethyl acid phosphate, dimethyl acid phosphate, mono(2-(meth)acryloyloxyethyl) acid phosphate, bis(2-(meth)acryloyloxyethyl) acid phosphate, tri(2-(meth)acryloyloxy-ethyl) acid phosphate and tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphonate.
BEST MODE FOR CARRYING OUT THE INVENTION
The photosensitive resin compositions contain an unsaturated compound and a photopolymerization initiator, and other substances such as polymer, plasticizer, colorant, etc., which are added as required according to the purpose of use. For mixing these substances, suitable methods can be employed, such as melting the solid components in an extruder and injecting the liquid components thereinto, or mixing together all of the substances in a Banbury mixer or a kneader.
BBHMAA used in the present invention is a compound represented by the following structural formula:
wherein R
1
and R
2
both represent an alkyl group. Because of high stabilizing effect, a compound of the above formula wherein both of R
1
and R
2
are methyl group (this compound 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate being hereinafter abbreviated as BBHMMA in some cases) is preferably used.
The content of the stabilizer BBHS is 0.01 to 5 parts by weight, preferably 0.1 to 0.9 parts by weight, per 100 parts by weight of the composition. The content of BBHMAA is 0 to 5 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the composition, more preferably equal to the content of BBHS. If the content of these stabilizers is below the above-defined ranges, the produced effect falls short of being satisfactory. If their content exceeds the above-defined ranges, there can not be obtained a greater effect than a certain level, and in this case, sensitivity of the composition may be lower.
Especially in the system containing a thermoplastic elastomer, additional incorporation of a phosphorus compound such as mentioned in (3) above is conducive to further promotion of the thermal stabilizing effect to improve the developing characteristics of the composition.
The stabilizer according to the present invention can be contained in the composition by a known method. For example, the stabilizer may be dissolved or uniformly dispersed in the liquid component so that it may be injected with the liquid component. In case the stabilizer is liquid, it may be injected separately from the liquid component, and if the stabilizer is solid, it may be supplied together with the solid component. Generally, the stabilizer is added before the process temperature rises up, but in order to enhance keeping quality of the final product, the stabilizer may be contained in the product by a specific method such as by impregnation.
As the unsaturated compound contained in the photosensitive resin composition, any compound can be used so far as it has a double-bond in the molecule and is liquid or solid at the working temperature. Preferably, the acrylic acid or methacrylic acid compounds having high reactivity and also high compatibility with various compounds are used, and the esters of acrylic or methacrylic acids are more preferably used because of lower toxicity and smaller metal corrosiveness.
Examples of such compounds include alkyl (meth)acrylate, cycloalkyl (meth)acrylate, halogenated alkyl (meth)acrylate, alkoxyalkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, aminoalkyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, glycidyl (meth)acrylate, benzyl (meth)acrylate, phenoxy (meth)acrylate, alkylen
Araki Yoshifumi
Oyoshi Takeshi
Asahi Kasei Kabushiki Kaisha
Birch & Stewart Kolasch & Birch, LLP
Chu John S.
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