Stock material or miscellaneous articles – Composite – Of silicon containing
Patent
1995-06-07
1998-03-10
Thisodeau, Paul J.
Stock material or miscellaneous articles
Composite
Of silicon containing
428519, 428522, 351166, B32B 1312, B32B 2716, B32B 2728, G02B 110
Patent
active
057259607
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a molded article the surface of which comprises a thermoplastic norbornene resin and has a hard coat layer excellent in adhesion thereto, a material for the molded article, a method for producing the molded article which comprises in combination a step of surface modification and a step of forming a primer layer, and a method for producing the molded article which includes a step of forming a multiple primer layer.
BACKGROUND ART
If lenses of spectacles and rear view mirrors for automobiles have a flaw on the surface, there are the problems that our eyes are adversely affected by irregular reflection, etc. and the images become inaccurate. Therefore, the surface hardness is increased by using a glass of high hardness or providing a hard coat layer on the surface of transparent resins. However, glass per se is heavy in weight and lacks flexibility.
On the other hand, hard coating agents used for transparent resins are roughly classified into silicone hard coating agents and organic hard coating agents. However, the organic hard coating agents are generally low in hardness and inferior in abrasion resistance and thus are insufficient in performances to be used for molded articles the surface of which readily flaws.
As for the silicone hard coating agents, when they are used on the molded articles having as its surface a thermoplastic norbornene resin which has recently been noticed as an optical material excellent in transparency, heat resistance and moisture resistance and low in birefringence, they are poor in wettability with the thermoplastic norbornene resin and insufficient in adhesion to the resin and as a result they suffer from the problem that the hard coat layer after cured peels off from the molded article. Moreover, thermoplastic norbornene resins having no polar group are high in chemical resistance and hence it is difficult to carry out surface treatment thereof and it is also difficult to sufficiently increase the adhesion only by chemical treatment. On the other hand, in the case of thermoplastic norbornene resins improved in adhesion by introducing a polar group, a hard coat layer having a certain adhesion can sometimes be formed, but the adhesion is practically not enough and furthermore, since the moisture resistance lowers due to the introduction of polar group, the layer readily peels off under severe conditions of high temperature and humidity. Moreover, since chemical resistance lowers, the surface dissolves to lose transparency when solvents used for general silicone hard coating agents are employed.
Accordingly, molded articles comprising thermoplastic norbornene resins and having a silicone hard coat layer excellent in adhesion to the surface of the molded articles have not yet been obtained.
DISCLOSURE OF INVENTION
As a result of intensive research on the adhesion between molded articles comprising a thermoplastic norbornene resin and a silicone hard coat layer, the inventors have found that a hard coat layer and the surface of molded articles can be allowed to firmly adhere to each other by carrying out modification of the surface of the molded articles and formation of a primer layer in combination or by carrying out formation of a multiple primer layer. Thus, the present invention has been accomplished.
According to the present invention, there are provided a molded article comprising a thermoplastic norbornene resin and having a silicone hard coat layer which has such adhesion to a substrate formed of the thermoplastic norbornene resin that the number of squares which are not peeled off when subjected to crosscut adhesion test is at least 50 squares per 100 squares (hereinafter referred to as "a crosscut adhesion of at least 50 squares per 100 squares"), a method for producing said molded article, characterized by comprising modifying the surface of a thermoplastic norbornene resin substrate so as to give a surface tension of 50 dynes/cm or more, forming a primer layer on the surface and then forming a silicone hard coat
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patent: 5437926 (1995-08-01), Takahashi et al.
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Encyclopedia or Polymer Science and Engineering, Sup. vol., pp. 674-689, 1985 ed.
Hosaka Tohru
Kohara Teiji
Konishi Yuichiro
Natsuume Tadao
Tada Mitsushi
Nippon Zeon Co. Ltd.
Tarazano D. Lawrence
Thisodeau Paul J.
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