JPS63213578A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having excellent hardness, adhesivity and durability under deformation of the coated optical material and suitable for the coating of a plastic material such as acrylic resin, by using a silane compound, an epoxy compound and a (meth)acrylic acid copolymer as active components. CONSTITUTION:The objective composition contains, as active components, (A) a methoxysilane compound, an ethoxysilane compound and/or their partially hydrolyzed compounds, (B) a compound having epoxy group and a methoxylated or ethoxylated silanol group (e.g. gamma-glycidoxypropylmethyldimethoxysilane) and (C) a terpolymer of (i) a compound of (meth)acrylic acid, (ii) one or more compounds comprising methyl or ethyl (meth)acrylate and (iii) an ester of (meth) acrylic acid and a 1-4C diol compound.

Description

DETAILED DESCRIPTION OF THE INVENTION r ′i*nfl /I′11. T41 m 8111
121 This invention relates to improvements in coating compositions for use on plastic optical materials such as polycarbonate and acrylic.

[Prior Art] Optical materials such as PlusDeck lenses are coated with various coatings to increase surface hardness. These coatings are required to be hard, have excellent adhesion to the optical material, have few coating defects, and have excellent durability when the optical material is deformed. No coating material is known that satisfies all of these requirements.

[Problem of the Invention] An object of the present invention is to provide a coating composition that provides a coating film that is excellent in hardness, adhesion, and durability when an optical material is deformed, and has few defects.

[Structure of the Invention] The coating composition of the present invention is characterized by using the following three types of compounds as active ingredients: 1) a group consisting of a methoxysilane compound, an ethoxysilane compound, and a partially hydrolyzed compound thereof; Compounds that are at least one member of: These compounds include, for example, methyltriethoxysilane: CHsSl(OCI■s)a, methyltriethoxysilane: Cl-13Si(OC*Hs)a, and aluyl compounds such as dimers and trimers of these. There are condensed compounds as well as partially hydrolyzed compounds thereof. These compounds are characterized by having a methoxy or ethoxy group bonded to silicon. Although tri-methoxy or triethoxy compounds are exemplified here, any silane compound containing a methoxy group or an ethoxy group may be used, for example, tetraethoxysilane: Si(OC!H5)4
, and dimethyldimethoxysilane: (CHs)zsi
(OCHs)t, or ethyltrimethoxysilane:
CvHsSt(OCHs)t, etc. may also be used.

2) Compound having an epoxy group and a methoxy or ethoxylated silanol group: This compound has two functional groups: an epoxy group and a methoxy or ethoxylated silanol group, and the epoxy group is a base optical material. 5i(OCHs) and 5i(OC1H)
The functional group 6) reacts with a silane compound. These compounds include, for example, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylethyljethoxysilane, or γ-glycidoxypropylethyldimethoxysilane.

3) A compound that is at least a member of the group consisting of acrylic acid or methacrylic acid; A compound that is at least a member of the group consisting of methyl or ethyl ester of acrylic acid or methacrylic acid; and acrylic acid or methacrylic acid having 1 to 4 carbon atoms. tri-copolymers of esters with diol compounds of: diol esters of acrylic acid or methacrylic acid include, for example, 2-hydroxypropyl methacrylate: CI 2
= C-COO-CI-1t-CHOI-I −
CHs, CI-1s 2-hydroxyethyl methacrylate: CH2=
C-COO-CH! -CHtOH.

CH3 2-hydroxypropyl acrylate: CH2=CH-
Coo-CHt-CHOH-CHs, 2-hydroxyethyl acrylate: CH2=CH-Coo-CHt-CHsOHl, etc. Here, diols having 2 to 3 carbon atoms are exemplified, but the number of carbon atoms may be 1 to 4, and the position of the hydroxyl group may be anywhere from 1 to 4 when viewed from the carboxyl group.

The basic behavior of each of these components is as follows. Acrylic or methacrylic copolymers have excellent adhesion to the substrate and durability against deformation of the substrate, and provide a coating film with few defects, but the hardness of the coating film is insufficient. On the other hand, silane compounds form a hard coating film, but are insufficient in terms of adhesion, durability against deformation, and few defects. Also, even if an epoxy compound is added to a silane compound,
The properties of the coating film are hardly improved. That is, although the hardness is lowered and the adhesion and resistance to deformation are improved to some extent, both values remain incomplete and the number of defects does not decrease. On the other hand, when a silane compound, an epoxy compound, and a copolymer are mixed, hardness, adhesion, and resistance to deformation are improved, and defects are reduced.

Such a coating composition is used by adding a leveling agent such as silicone oil and a solvent such as water or methanol so that it can be coated on an optical material.

A preferable mixing ratio of each component is a molar ratio of silane compound to epoxy compound of 3:2 to 12:1, more preferably 2:l to 6:l, with the silane compound being more important than the epoxy compound. Add in large quantities.

What is important for acrylic and methacrylic copolymers is the weight ratio of the total amount of silane compound and epoxy compound to the copolymer. A preferred weight ratio of the total weight of the silane compound and the epoxy compound to the weight of the Noti lightning combination is 5:1 to 20:1, more preferably 8:1.
-15:1.

Next, the methacrylic acid and acrylic acid in the copolymer react with the epoxy compound to increase the hardness of the coating film.

Furthermore, the hydroxy compound in the copolymer contributes to improving the adhesion and hardness of the coating film. Next, if methacrylic acid or acrylic acid is directly copolymerized with a hydroxy compound, only a gel-like copolymer will be obtained and no coating composition will be obtained. On the other hand, when ethyl or methyl ester of methacrylic acid or acrylic acid is added and copolymerized in a three-component system, gelation does not occur and a coatable copolymer is obtained.

The composition of the copolymer is preferably 70-90:30-10 in molar ratio of ester such as methyl methacrylate to the total amount of hydroxy compound and acid such as methacrylic acid.

Moreover, the molar ratio of the hydroxy compound and the acid such as acrylic acid is preferably 3:1 to 1:1. Therefore, the content in the copolymer is in the order of ester, hydroxy compound, and acid.

[Examples] Examples are explained below, but are not limited to these.
Appropriate changes can be made within the range of known techniques.

Preparation of coating solution 160 g of methyl methacrylate, 39 g of 2-hydroxyethyl methacrylate, and 8.6 g of methacrylic acid were mixed, and benzoyl peroxide was added as a polymerization initiator in a dioxane solvent, and polymerization was carried out at 85 to 90°C for 2 hours. . The average molecular weight determined from the intrinsic viscosity of the obtained copolymer was 18
It was 10,000.

In the same manner, methyl methacrylate was replaced with ethyl methacrylate, and 2-hydroxyethyl methacrylate was replaced with 2-hydroxypropyl methacrylate. In addition, products were prepared in which each methacrylic acid compound was replaced with an acrylic acid compound.

A mixed solvent of dilute hydrochloric acid (0.02N) and methanol at a weight ratio of 4:3 was kept at 15 to 20°C under water cooling, and a silane compound such as methyltriethoxysilane and methyltriethoxysilane and γ-glycidoxypropylethyl were mixed. Epoxy compounds such as jetoxysilane and γ-glycidoxypropylmethyldimethoxysilane were added dropwise. 3-5 after completion of dripping
Stirring was continued under water cooling for an hour to hydrolyze these (b' compounds).

After hydrolysis, the above copolymer was added as a reaction solution, a sodium acetate curing catalyst was mixed with a silane compound such as methyltrimethoxylan at a ratio of 0.6% by weight, and methanol and a silicone oil leveling agent were added. was added to complete the coating liquid.

A polycarbonate lens having a diameter of 78 mm was immersed in the hood coating solution and coated at a pulling rate of 0 and 4 am/sea, followed by heat treatment at 120° C. for 2 hours. The coated lenses were evaluated in terms of the hardness of the coating, adhesion to the base, durability against bending deformation, and coating defects. The evaluation used four lenses for each coating solution, and the results were in good agreement.

The hardness of the coating film was evaluated by applying a load of Ikg to #000 sudir wool and moving it back and forth over the coating film three times, and based on the number of scratches that occurred. If there are 2 or less scratches, it will be considered as Palanc, and if there are 3 to 10 scratches, it will be considered as B.
Rank: 11 to 30 were ranked C, and 31 or more were ranked D.

To test the adhesion, soak the lens in warm water at 85°C for 30 minutes, let it cool, then apply cellophane tape and peel off the tape.
Those in which the paint film peeled off together with the tape were ranked C. For the samples whose paint film did not peel off, the same test was conducted by changing the immersion time in warm water to 1 hour. Those in which the paint film peeled off along with the cellophane tape were ranked B, and those in which the coating did not peel off were ranked Pal.

Force was applied to the lens from both ends to compress it by 15 mm.

The occurrence of cracks in the paint film during this process was inspected, and those with no cracks were ranked A, those with 1 to 5 cracks were ranked B, and those with 6 or more cracks were ranked C. .

The number of pinholes that occur in the paint film is visually inspected, and if there are no pinholes, it is ranked as a rank, and if there are 5 or less, it is ranked as a B rank.
Those with 20 or fewer pieces were ranked C, and those with more than 20 were ranked D. In most cases, D-rank items had countless pinholes.

Table 1 shows the basic effects of each component. Both the single copolymer and the single methyltrimethoxysilane have insufficient properties. Further, even a mixture of methyltrimethoxysilane with an epoxy compound and a copolymer with methyltrimethoxysilane have insufficient properties.

However, with methyltrimethoxysilane and epoxy compounds,
In the examples in which a copolymer was mixed, excellent results were obtained in all respects.

Table 2 shows the mixed ratio of the prepared samples, and Table 3 shows the characteristics. The preferred range of mixing ratios and types of raw materials will be clear from Tables 2 and 3.

Table I
A coating composition is obtained.

Claims (1)

[Claims] (1) 1) A compound that is at least one member of the group consisting of methoxysilane compounds, ethoxysilane compounds, and partially hydrolyzed compounds thereof, 2) A compound having an epoxy group and a methoxy or ethoxylated silanol group, and 3 ) a compound of at least one member of the group consisting of acrylic acid or methacrylic acid; a compound of at least one member of the group consisting of methyl or ethyl ester of acrylic acid or methacrylic acid; and a compound of acrylic acid or methacrylic acid having 1 to 4 carbon atoms. A coating composition comprising as an active ingredient a copolymer of a diol compound, an ester, and a tri-component.