JPH04353801A - Production of plastic optical element - Google Patents

Abstract

PURPOSE:To offer the production method of plastic optical element having a polyorganosiloxane hardened film which is excellent in surface hardness and adhesion property to the base body. CONSTITUTION:A mixture of monomers essentially comprising components (a) and (b) is molded and polymerized to obtain the plastic molded body. These components are (a) at least one kind of methacrylic monomer selected from monofunctional methacrylates and polyfunctional methacrylates and (b) at least one kind of hydrophilic monomer selected from (meth)acrylic acids and (meth) acrylates containing hydroxyl groups. The obtd. plastic molded body is subjected to plasma treatment, on which a coating compsn. essentially comprising components (c) and (d) is applied and hardened to form a hardened film. Thus, the plastic optical element is obtd. These components are (c) an org. silicon compd. having a silanol group and an epoxy group and (d) colloidal silica.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plastic optical element made of acrylic resin and having a cured film with high hardness and excellent adhesion on its surface.

0002

[Prior Art] Transparent plastics, especially acrylic resins represented by methyl methacrylate polymer, have good transparency and light weight, and are easy to process, so they are used in instrument covers, lenses, and filters. It is used in many fields as an optical element such as a prism. However, since acrylic resins generally do not have sufficient surface hardness, this problem is solved by coating the surface as necessary to form a surface hardening film. Methods of using organopolysiloxane-based, polyfunctional acrylate-based, and amino resin-based curing liquids for surface-curing films are known. Among these methods, when the base material is an acrylic resin, polyfunctional acrylate-based curing liquids are used. The method used is the mainstream. However, methods using multifunctional acrylate curing liquids generally use strong ultraviolet rays during curing, but dyes, infrared absorbers, photochromic substances, etc. are also added to the base material or cured film to increase product value. In this case, the effect is likely to diminish or disappear due to UV irradiation during curing.
There is a problem that the base material or the cured film yellows and deteriorates. Therefore, it is known to use an organopolysiloxane curing liquid to improve these properties. As an example of using an organopolysiloxane curing liquid for this acrylic resin, JP-A-61-166824 discloses a coating composition comprising a hydrolyzate of an organosilicon compound, an epoxy resin compound, and an epoxy curing agent. ing.

0003

[Problems to be Solved by the Invention] However, the coating film obtained from the organopolysiloxane composition disclosed in JP-A No. 61-166824 has insufficient surface hardness. Poor abrasion resistance against heavy cleaning and contact. Therefore, when a metal colloid, which is a general abrasion resistance improver, is added to this organopolysiloxane composition, the film hardness is improved, but there is a problem in that the adhesion with the base resin is significantly reduced. Ta. This trend is
This phenomenon becomes more noticeable when the crosslinking density of the base resin is increased in order to improve strength, heat resistance, solvent resistance, etc.

[0004] In addition, common methods for increasing the adhesion between the base resin and the cured film include pre-treating the base resin with chemicals such as acids and alkalis, and plasma-treating the base resin. , a method of providing a primer layer between the base resin and the cured film, and the like. However, in order to overcome these drawbacks of acrylic resin and to ensure sufficient adhesion of the cured film, conventional acid or alkali treatment or plasma treatment is completely insufficient, and the only method is to provide a primer layer. It was an effective method.

However, the biggest problem with this method is that the primer layer and cured film must be coated, dried, and cured by heating, making the process complicated and increasing the chances of contamination with foreign substances during this process. Therefore, there was an aspect that it was not practical.

The present invention has been made to solve the above-mentioned problems, and its object is to provide a plastic optical element having a polyorganosiloxane cured film that has excellent surface hardness and adhesion to a substrate. The purpose of this invention is to provide a method for manufacturing the same.

[0007]

[Means for Solving the Problems] A method for manufacturing a plastic optical element of the present invention that achieves the above object includes the following steps (
It is characterized by including 1), (2) and (3). (1) A step of obtaining a plastic molded article by cast-polymerizing a monomer mixture containing the following components (a) and (b) as main components. (a) at least one methacrylic monomer selected from monofunctional methacrylic esters and polyfunctional methacrylic esters, (b) at least one methacrylic monomer selected from (meth)acrylic acid and hydroxyl group-containing (meth)acrylic esters (2) A step of plasma-treating the plastic molded article obtained in step (1). (3) A coating composition containing the following components (c) and (d) as main components is applied to the plastic molded body subjected to the plasma treatment in step (2) and cured to form a cured film to make plastic optical Process of obtaining elements. (c) an organosilicon compound having a silanol group and an epoxy group; (d) colloidal silica. As described above, the method for manufacturing a plastic optical element of the present invention includes steps (1), (
2) and (3). These steps will be explained one by one.

Step (1) Step (1) is a step of obtaining a plastic molded article by cast-polymerizing a monomer mixture containing components (a) and (b) as main components. The reason for using the methacrylic monomer as component (a) as the monomer is to enable the resulting plastic optical element to exhibit excellent optical properties such as high transparency and high Abbe number, which are possessed by the acrylic resin. As the methacrylic monomer of component (a), at least one selected from monofunctional methacrylic esters and polyfunctional methacrylic esters is used. Examples of monofunctional methacrylate esters include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, ethylhexyl methacrylate, benzyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, etc. In addition, as a polyfunctional methacrylic ester,
Examples include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, glycerin dimethacrylate, etc. It will be done. The preferred content of the methacrylic monomer as component (a) is 30 to 95% by weight, more preferably 40 to 95% by weight, based on the total monomer mixture. If the content of these monomers is less than 30% by weight in the total monomer mixture, problems such as the inability to obtain the excellent transparency and light resistance inherent to acrylic resins and insufficient strength will occur. If it exceeds % by weight, it is a monomer with a hydrophilic group (b
) Since the content of the component is relatively reduced, the improvement in adhesion to the cured film becomes insufficient.

As the hydrophilic monomer as component (b), at least one selected from (meth)acrylic acid and hydroxyl group-containing (meth)acrylic ester is used. In this specification, "(meth)acrylic acid" means "
It means both ``acrylic acid'' and ``methacrylic acid.'' Examples of these include acrylic acid, methacrylic acid, hydroxyethyl esters of acrylic acid or methacrylic acid,
Examples include chlorohydroxypropyl ester of acrylic acid or methacrylic acid. The content of these monomers is preferably 5 to 50% by weight, more preferably 5 to 30% by weight, based on the total monomer mixture. If these monomers are less than 5% by weight of the total monomer mixture, the adhesion to the cured film will not be sufficiently improved, and if it exceeds 50% by weight, water absorption will increase and the physical properties of the resin surface will deteriorate. Becoming unstable and rough;
It is more likely to cause pockmarks, etc. In addition, problems such as poor mold releasability during mold forming, making it difficult to obtain good transferability and making molding difficult, are undesirable as optical elements.

In the present invention, other monomers copolymerizable with these monomers may be added to the extent that the effects of the invention are not impaired. Examples of such monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, ethylhexyl acrylate, silohexyl acrylate, benzyl acrylate, phenyl acrylate, isobornyl acrylate, ethylene glycol diacrylate, Acrylic acid esters such as ethylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, styrene, methylstyrene, dimethylstyrene, chlorstyrene, dichlorostyrene, promustyrene, p Examples include nuclear substituted styrenes such as -chloromethylstyrene and divinylbenzene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, and N-substituted maleimide.

[0011] In step (1), a cast polymerization method is used to produce the plastic. In terms of polymerization energy, ultraviolet curing polymerization and radiation curing polymerization are also used, but thermosetting polymerization is usually adopted. That is, a suitable amount of a polymerization initiator is added to a monomer mixture, and the mixture is poured into a mold and polymerized by heating. As the polymerization initiator at this time, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,
Azo initiators such as 4-dimethylvaleronitrile) can be suitably used. Peroxide-based initiators such as benzoyl peroxide, lauroyl peroxide, and t-butyl peroxy-2-ethylhexanoate can also be used; When adding an initiator whose effect is likely to be reduced or eliminated, it is better to use an azo initiator. It is usually preferable to use these initiators in an amount of 0.001 to 5.0% by weight based on the total amount of monomers. Further, the heating polymerization temperature varies depending on the initiator used, but is usually in the range of 20 to 80°C.

[0012] In addition, small amounts of heat stabilizers, antioxidants, ultraviolet absorbers, mold release agents, antistatic agents, etc. can also be contained in the plastic molded article, if necessary. Step (2) The plastic molded body obtained in step (1) is subjected to this step (
In 2), plasma treatment is performed. Through this plasma treatment, the plastic molded body obtained in step (1) and the step (
Adhesion with the cured film provided in step 3) is improved. The conditions for plasma processing vary depending on the size, type, and shape of the equipment used, but in the present invention, air, helium,
Non-polymerizable gases such as argon, hydrogen, oxygen, nitrogen, etc. 0.0
This is carried out within 60 seconds in an atmosphere of 1 to 10 Torr.

Step (3) A coating composition is applied and cured to form a cured film in step (3), preferably within 24 hours, to the plastic molded article that has been subjected to the plasma treatment in step (2).

The coating composition used in the present invention comprises an organosilicon compound having a silanol group and an epoxy group in the molecule [component (c)], colloidal silica [component (d)]
It is necessary to include As component (c), an organosilicon compound having at least two silanol groups and at least one epoxy group in the molecule is preferable, and specific examples thereof include the general formula

[0015]

[Chemical formula 1]

(In the formula, R1 is an alkyl group having 1 to 4 carbon atoms, and R2 is an alkylene group having 1 to 4 carbon atoms.)
A hydrolyzate obtained by hydrolyzing a trifunctional organosilicon compound represented by: Note that R1 in the formula is a methyl group, ethyl group, propyl group, or butyl group, and R2
is more preferably a methylene group, an ethylene group, a propylene group or a butylene group.

On the other hand, the colloidal silica as component (d) is a highly concentrated water-dispersed colloidal silica (for example, SiO2 solid content of 40% or more) in order to leave as little excess water as possible after the hydrolysis of the organosilicon compound. ) are preferably used. The average particle diameter is preferably in the range of 5 to 100 mμ, more preferably 5 to 30 mμ. By using an organopolysiloxane coating composition containing a high concentration of colloidal silica, a cured film with higher hardness can be obtained. Therefore, the coating compositions used in the present invention exhibit their usefulness when they contain high concentrations of colloidal silica. In this sense, in the present invention, the amount of colloidal silica in the coating composition is preferably set to 55 to 90 mol % (SiO2 solid content equivalent value) based on the total amount of colloidal silica and organosilicon compound, and more preferably. The range is 7
It is 5 to 90 mol%.

Curing agents are commonly used, examples of which include imidazole derivatives, but acetylacetone metal complex compounds, particularly acetylacetone aluminum complex compounds, are particularly effective. The amount added is sufficient to harden the colloidal silica and the hydrolyzate of the organosilicon compound, i.e., 1 to 10% per mol of the total of colloidal silica (SiO2 equivalent) and the hydrolyzate of the organosilicon compound.
Preferably, it is g.

Note that an organic acid is used for hydrolyzing the organosilicon compound of formula (I). Examples of this include formic acid, acetic acid, and propionic acid, but acetic acid is preferably used from the viewpoint of stability of the coating composition. The amount of organic acid added is 1 mol of the total amount of colloidal silica and organosilicon compound.
It is preferable that it is 5 to 30 g. If the amount is less than this, gelation of the coating composition tends to occur, and if it is more than this, the odor becomes strong and is not favorable for work.

[0020] Furthermore, in order to make the hydrolysis uniform and to appropriately control the degree of hydrolysis, it is preferable to add an appropriate solvent to the coating composition. As such a solvent, cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve are preferred, and combinations with isopropyl alcohol, butanol, etc. are more preferred. The proportion of cellosolve is preferably 3% by weight or more, particularly preferably 10% by weight or more based on the total amount of solvent. When the proportion of colloidal silica is high, gelation tends to occur during preparation of the coating composition if the proportion of cellosolve in the solvent is less than 3% by weight of the total amount of solvent.

A silicone surfactant may also be added to the coating composition used in the present invention for the purpose of improving the smoothness of the coating film. Furthermore, it is also possible to add ultraviolet absorbers, antioxidants, etc. for the purpose of improving light resistance or preventing deterioration of the coating film.

[0022] The coating composition can be applied to the plastic molded body by dipping, spin coating, roll coating, spraying, or the like. The applied coating composition is cured by heat treatment, and the heating temperature is preferably 40 to 150°C, particularly preferably 80 to 130°C. The heating time is preferably 1 to 4 hours. The cured film obtained after applying and curing the coating composition has excellent adhesion to the plastic molded body because the plastic molded body has been subjected to plasma treatment in step (2). Incidentally, after the cured film is formed, the cured film can also be coated by vapor deposition.

[0023]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. The methods for evaluating physical properties in Examples and Comparative Examples are as follows.

(a) Surface hardness The surface was rubbed 50 times (back and forth) with steel wool #0000 under an additional load of 1000 g, and the scratch resistance was judged based on the following criteria. A: Almost no damage. B: Very slight scratches. C: Slight damage. D: Many scratches occur.

(b) Adhesive The cured film surface was cut into gobbles (10 x 10 pieces) at 1 mm intervals, and cellophane adhesive tape (Nichiban Co., Ltd. No.
．． 405) was firmly attached and then rapidly peeled off in a 90-degree direction to determine the number of remaining gobans.

(c) Appearance Transparency, coloring state, surface state, etc. were examined visually.

[Preparation of coating composition] SiO2
Colloidal silica (Snowtex-40) with a concentration of 40%
, water-dispersed silica, average particle size 10-20 mμ, Nissan Chemical (
Co., Ltd.), 2.0 parts by weight of 0.5N hydrochloric acid, and 20 parts by weight of acetic acid were heated to 35°C and heated to γ while stirring.
95 parts by weight of -glycidoxypropyltrimethoxysilane (a trifunctional organosilicon compound) was added dropwise, stirred at room temperature for 8 hours, and then left to stand for 16 hours. This hydrolysis solution 320
Parts by weight include 80 parts by weight of methyl cellosolve, 120 parts by weight of isopropyl alcohol, 40 parts by weight of butyl alcohol,
16 parts by weight of aluminum acetylacetone, 0.2 parts by weight of a silicone surfactant, and 0.1 parts by weight of an ultraviolet absorber were added, stirred for 8 hours, and then aged at room temperature for 24 hours to obtain a coating composition. Coating composition (A)
shall be. At this time, the amount of colloidal silica in the coating composition is 80 mol based on the total amount of colloidal silica and γ-glycidoxypropyltrimethoxysilane.
% (SiO2 solid content equivalent value).

A coating composition (B) was obtained in the same manner as in the preparation of the coating composition (A) except that the amount of γ-glycidoxypropyltrimethoxysilane was changed to 67 parts by weight. The amount of colloidal silica in the coating composition at this time is 85 mol based on the total amount of colloidal silica and γ-glycidoxypropyltrimethoxysilane.
% (SiO2 solid content equivalent value).

Coating composition (C) was prepared in the same manner as coating composition (A) except that the amount of γ-glycidoxypropyltrimethoxysilane was changed to 253 parts by weight.
I got it. The amount of colloidal silica in the coating composition at this time is 60 mo based on the total amount of colloidal silica and γ-glycidoxypropyltrimethoxysilane.
1% (SiO2 solid content equivalent value).

[0030] Ion exchange water 1 instead of colloidal silica
A coating composition (D) was obtained in the same manner as the preparation of the coating composition (A) except that 20 parts by weight was used.

[Example 1] 60 parts by weight of methyl methacrylate, 20 parts by weight of methacrylic acid, 20 parts by weight of ethylene glycol dimethacrylate, 0.30 parts by weight of azobis-based radical polymerization initiator (azobisisobutyronitrile), ultraviolet light Absorbent (Tinuvin P manufactured by Ciba Geigy) 0.0
5 parts by weight, mold release agent (Shin-Etsu Silicone K manufactured by Shin-Etsu Chemical Co., Ltd.)
F353A) 0.01 part by weight was added and mixed and dissolved. This mixture was injected into a mold consisting of two glass molds and a plastic gasket, and the mixture was placed in a hot air circulation heating furnace and heated at 50°C for 12 hours, then raised to 85°C over 4 hours. The mixture was heated as it was for 2 hours to carry out polymerization. The polymer obtained after removing the mold was a highly transparent plastic molded body forming a meniscus lens with a diameter of 75 mm, a thickness of 2.0 mm, and a power of 0.00 diopter. This was further heated at 120° C. for 2 hours to perform annealing.

This plastic molded article was subjected to plasma treatment for 1 second in a nitrogen atmosphere of 0.6 Torr using PR-501A manufactured by Yamato Scientific Co., Ltd.

[0033] Subsequently, coating composition (A) was applied by a dipping method (pulling speed: 20 cm/min) and cured by heating at 120°C for 90 minutes to form a cured film.

The evaluation results of the thus obtained optical element with the cured film were excellent in surface hardness, adhesion, and appearance, as shown in Table 1.

[Examples 2 to 10] The same procedure as in Example 1 was carried out except that the plasma treatment conditions shown in Table 1 and coating compositions (A), (B), and (C) containing SiO2 were used. An optical element with a cured film was produced and evaluated in the same manner. The results were excellent as shown in Table 1. [Comparative Examples 1 to 3] Optical elements with cured films were produced in the same manner as in Example 1, except that the plasma treatment conditions shown in Table 1 and the coating composition (D) containing no SiO2 were used. Example 1). Furthermore, coating composition (A) containing SiO2 and S
Optical elements with cured films were obtained in the same manner as in Example 1, except that coating compositions (D) containing no iO2 were used (Comparative Examples 2 and 3). As shown in Table 1, the evaluation results were poor in film hardness and adhesion. [Comparative Examples 4 to 6] Optical elements with cured films were produced in the same manner as in Example 1, except that chemical treatment as shown in Table 1 was performed instead of plasma treatment, and evaluation was performed in the same manner. The results, as shown in Table 1, were poor in film hardness and adhesion.

[0036]

[Table 1]

[Examples 11 to 16] (
Optical elements with cured films were produced in the same manner as in Example 1, except that the hydrophilic monomer as component b) was changed as shown in Table 2, and evaluated in the same manner. As shown in Table 2, the results were excellent in surface hardness, adhesion, and appearance.

[0038]

[Table 2]

[Examples 17 to 24] Optical elements with cured films were prepared in the same manner as in Example 1, except that the composition of the monomer mixture was changed as shown in Table 3, and evaluations were conducted in the same manner. . As shown in Table 3, the results were excellent in surface hardness, adhesion, and appearance.

[Comparative Example 7] Table 3 shows the composition of the monomer mixture.
A lens was produced in the same manner as in Example 1, except for the following changes, and evaluated in the same manner. The results showed that if the composition of the monomer mixture did not meet the requirements of the present invention, the film hardness and adhesion were poor as shown in Table 3.

[0041]

[Table 3]

[Example 25] A near-infrared absorber (SIR-11 manufactured by Mitsui Toatsu Dye Co., Ltd.) was added to the monomer mixture of Example 1.
4) 0.06 parts by weight was added and the rest was carried out in the same manner as in Example 1 to produce an optical element. This optical element has excellent surface hardness of A and cured film adhesion of 100/100, which is 650-78
Since it selectively absorbs light with a wavelength of 0 nm, it could be suitably used as a lens for laser safety glasses.

As can be seen from these Examples, according to the present invention, a good cured film having extremely high hardness and excellent adhesion can be provided to an acrylic resin. On the other hand, as can be seen from the comparative examples, if any of the requirements constituting the present invention, i.e., the base resin composition, plasma treatment, or coating composition, is inappropriate or lacking, a good optical element cannot be obtained. . Further, the present invention can be effectively applied to a functional lens like Example 25.

[0044]

According to the present invention, a cured film having extremely high hardness and high durability, which has been mainly used for diethylene glycol bisallyl carbonate resin, can be brought into sufficient adhesion to an acrylic resin. Moreover, according to the present invention, the contamination caused by foreign substances during the process, which was a problem with the conventional method using a primer layer, can be halved, so it is extremely practical.

Claims (2)

[Claims] Claim 1: The following steps (1), (2) and (3)
) A method for producing a plastic optical element, the method comprising: (1) A step of obtaining a plastic molded article by cast-polymerizing a monomer mixture containing the following components (a) and (b) as main components. (a) at least one methacrylic monomer selected from monofunctional methacrylic esters and polyfunctional methacrylic esters, (b) at least one methacrylic monomer selected from (meth)acrylic acid and hydroxyl group-containing (meth)acrylic esters (2) A step of plasma-treating the plastic molded article obtained in step (1). (3) A coating composition containing the following components (c) and (d) as main components is applied to the plastic molded body subjected to the plasma treatment in step (2) and cured to form a cured film to make plastic optical Process of obtaining elements. (c) an organosilicon compound having a silanol group and an epoxy group; (d) colloidal silica. 2. The method of claim 1, wherein the plastic optical element is a spectacle lens.