Coating processes – With post-treatment of coating or coating material – Heating or drying
Reexamination Certificate
1999-10-12
2001-01-23
Cameron, Erma (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Heating or drying
C427S393500
Reexamination Certificate
active
06177138
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an abrasion-resistant coating composition for an acrylic resin molded article and to a coating method using the composition. More particularly, the present invention relates to a coating composition used for forming a hard coat layer on the surface of an acrylic resin molded article and to a coating method.
PRIOR ART
The hard coat treatment of the surface of a plastic has been conducted, for example, by the methods disclosed in the following Laid-Open Patent Publications.
JP-A 59-108064 discloses a hard coat solution for forming a hard coat layer on the surface of an acrylic resin molded article, which comprises the following components (a) to (d):
(a) a hydrolyzate and/or a partial hydrolyzate of a silicon-containing compound having the following structural formula:
R
n
Si(OR′)
m
wherein R is an organic group having 1 to 9 carbon atoms, R′ is an alkyl group having 1 to 3 carbon atoms, n is 1 to 3, and m is 3 to 1;
(b) colloidal silica using water and/or alcohol as a dispersion medium;
(c) colloidal antimony oxide using water and/or alcohol as a dispersion medium; and
(d) a lower aliphatic alcohol for dissolving the above components (a) to (c).
The hard coat solution having the above composition is coated on a plastic such as a plastic lens and heat-cured to prevent the surface of the plastic from being abraded.
JP-A 8-238683 discloses a hard coating agent comprising a particular silane compound and/or a hydrolyzate thereof, surface-modified titanium oxide fine particles and aluminum perchlorate. It is emphasized in the publication that aluminum perchlorate is a curing catalyst which is essential to prevent the appearance of interference fringes and the whitening of a formed film because such prevention is not attained by any known curing catalyst.
Meanwhile, the following four molding methods are known for the production of an acrylic resin molded article. The acrylic resin molded articles produced by these molding methods differ from each other in their adhesivity to a hard coat layer formed thereon.
Molding methods
Adhesivity to hard coat
(1) Extrusion-molded article
Good
(2) Injection-molded article
Good
(3) Cell-casting-molded article
Poor
(4) Continuous-casting molded article
Poor
In the molded articles (1) and (2), resins used as raw materials must have a relatively low molecular weight because they are melted in molding. When the hard coat solution contains a lower aliphatic alcohol such as ethanol or isopropyl alcohol, the molded articles (1) and (2) undergo appropriate etching by the lower aliphatic alcohol, giving rise to adhesivity between the molded article and the hard coat.
Meanwhile, the molded articles (3) and (4) are different from the molded articles (1) and (2) in that they gives rise to a polymerization reaction during molding. Although it is not known whether or not this is connected with the above-mentioned polymerization reaction of raw material acrylic resin, none of conventional hard coat solutions has shown sufficient adhesivity to cell-casting-molded or continuous-casting-molded articles of an acrylic resin.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide an abrasion-resistant coating composition for an acrylic resin molded article.
It is another object of the present invention to provide an abrasion-resistant coating composition showing sufficient adhesivity to molded articles produced by any molding method.
It is still another object of the present invention to provide a method for coating an acrylic resin molded article using the above coating composition of the present invention.
Still other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are achieved by an abrasion-resistant coating composition for an acrylic resin molded article, comprising:
(A) at least one kind of a silicon compound selected from the group consisting of organic silicon compounds represented by the following formula (1):
R
1
R
2
a
Si(OR
3
)
3−a
(1)
wherein R
1
is an alkyl group, an alkenyl group, a halogenoalkyl group, an aryl group, an aralkyl group or a halogenoaryl group; R
2
is an alkyl group, an alkenyl group, a halogenoalkyl group, an aryl group, an aralkyl group or an alkyl group having epoxy group, amino group, mercapto group, methacryloxy group or acryloxy group; R
3
is a hydrogen atom, an alkyl group or an acyl group; and a is 0 or 1,
and partial hydrolyzates thereof,
(B) a dispersion sol of metal oxide fine particles,
(C) a curing agent, and
(D) benzyl alcohol.
The above objects and advantages of the present invention are achieved, secondly, by a process for producing an acrylic resin molded article having an abrasion-resistant coating film thereon, which comprises applying the coating composition of the present invention on at least part of the surface of the acrylic resin molded article and then drying and curing the formed wet film.
DETAILED DESCRIPTION OF THE INVENTION
The base material for the coating composition of the present invention may be any acrylic resin or flame-retardant acrylic resin molded article obtained by injection molding, cell-casting molding or continuous-casting molding.
The thickness in which the coating composition is coated on the above molded article is preferably 1 to 8 &mgr;m in terms of solid content. The coating film formed is cured preferably under the conditions of 70 to 90° C. for 0.5 to four hours. The coating composition can be coated on the above molded article, for example, by flow coating, dip coating, spray coating, spin coating, roller coating or curtain flow coating.
The coating composition of the present invention shows sufficient adhesivity not only to cell-casting- or continuous-casting-molded articles but also to extrusion- or injection-molded articles. Further, the coating composition also shows good adhesivity to colored acrylic resin molded articles. Moreover, the coating composition also shows good adhesivity to all of the flame-retardant-containing acrylic resin molded articles produced by each of the four production methods mentioned above.
As the flame-retardant, there can be mentioned, for example, halogen-based, phosphorus-based or inorganic flame-retardants; and flame-retardants of phosphates, haloalkyl phosphates or their polyphosphates. Of these, preferred are flame-retardants of phosphate type, haloalkyl phosphate type or their polyphosphate type because they can maintain the transparency of an acrylic resin molded article.
As specific examples of the flame-retardant, there can be mentioned halogen-based flame-retardants such as tetrabromobisphenol A, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane and the like; phosphorus-based flame-retardants such as tricresyl phosphate, trischloroethyl phosphate and polyphosphate thereof; and inorganic flame-retardants such as antimony trioxide, zirconium hydroxide, barium metaborate, tin oxide and the like.
The base material consisting of an acrylic resin molded article in the present invention is a polymer composed mainly of methyl methacrylate. As its copolymer component(s), there can be mentioned acrylic acid esters, acrylic acid, acrylonitrile, etc. The base material used in the present invention also includes those containing an acrylic rubber or a butadiene rubber or those containing a crosslinking agent.
Next, description is given on the individual components constituting the coating composition of the present invention.
Firstly, as the component (A), there is used at least one compound selected from the group consisting of organic silicon compounds represented by the following formula (1) and partial hydrolyzates thereof.
R
1
R
2
a
Si(OR
3
)
3−a
(1)
wherein R
1
is an alkyl group, an alkenyl group, a halogenoalkyl group, an aryl group, an aralkyl group or a halogenoaryl group; R
2
is an alkyl group, an alkenyl group, a halogenoalkyl group, an aryl group, an aralkyl group or a
Sawaragi Fujio
Sonezaki Hizashi
Cameron Erma
Nippon ARC Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Abrasion-resistant coating composition for acrylic resin... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Abrasion-resistant coating composition for acrylic resin..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Abrasion-resistant coating composition for acrylic resin... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2556578