JPS6231746B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to transparent plastic materials having a dyeable scratch-resistant coating, and in particular to plastic lenses used as spectacle lenses having a dyeable scratch-resistant coating. Plastic lenses are used as lenses for eyeglasses. Polycarbonate polymers, acrylic polymers, styrene polymers, and other transparent plastics are known as materials for plastic lenses, but some of them have excellent optical properties such as impact resistance and transparency. “CR-39” lenses are the most suitable plastic lenses. CR―
39 is the trade name for diethylene glycol bisallyl carbonate, and this monomer will be referred to below as
It is called CR-39 or CR-39 monomer, this homopolymer or copolymer is called CR-39 polymer, and a plastic lens made of CR-39 polymer is called CR-39 lens. As mentioned above, CR-39 lenses are already widely used as eyeglass lenses, taking advantage of their advantages of being lightweight, impact resistant, transparent, and having excellent optical properties. However, CR-39 lenses do not have sufficient surface hardness, and the scratches they receive while using them as eyeglass lenses cause scratches on the surface, which reduces their transparency and shortens their usable life as eyeglass lenses. is considered to be a problem. Therefore, in the present invention, we have developed a material that increases the surface hardness of the CR-39 lens to a level that can be used practically and extends its usable life as an eyeglass lens. We also considered creating a scratch-resistant coating that also has good adhesion to CR-39 lenses. Conventional scratch-resistant coating materials that increase the surface hardness of CR-39 lenses include organic materials such as melamine resin and epoxy resin, inorganic materials such as silica applied to the substrate surface by vapor deposition, and organic silane compounds. Organic-inorganic materials typified by polyalkylsiloxanes obtained by hydrolyzing are known. Among these, organic materials do not have sufficient scratch resistance, and when the same dyeing material is used, the dyeing speed and color tone are CR-
This was very different from the 39 lens itself and was a practical problem. On the other hand, inorganic materials and organic-inorganic materials have sufficient hardness, but have the major disadvantage that they are expensive at the time of material or molding, and cannot be dyed under practical conditions. The present inventors previously studied coating compositions for forming scratch-resistant films on transparent plastic materials, and discovered a coating composition that had excellent scratch resistance as well as adhesion to transparent plastic materials, and filed a patent application. (Special request 1982-
(See No. 43527). The present inventor applied this excellent coating composition to a CR-39 lens and examined the stainability of the resulting CR-39 lens having an abrasion-resistant coating. Contrary to expectations, we found that the dyeing properties of CR-39 lenses with this scratch-resistant coating were far superior to CR-39 lenses with conventional scratch-resistant coatings. A particular advantage is that it can be dyed using almost the same staining method and staining solution as for CR-39 lenses, which do not have a normal scratch-resistant coating. However, since the dyeability of the coating composition described above was not considered, it was found that the dyeing speed was not appropriate, color unevenness was likely to occur, and the dyed hue was not fully satisfactory. The present inventors have considered further improving the coating composition from the viewpoint of dyeability. As a result, they found that the type of polyhydric alcohol in the coating composition has an effect on the dyeability, and that it is necessary to precondense the reactive components in advance. The improved coating composition is capable of forming an excellent scratch resistant coating on CR-39 lenses as well as other transparent plastic materials and provides good stainability. This invention relates to transparent plastic materials having improved dyeable scratch-resistant coatings, and more particularly to CR-39 lenses having improved dyeable scratch-resistant coatings. That is, the present invention comprises a transparent plastic material comprising a homopolymer of diethylene glycol bisallyl carbonate or a copolymer with a copolymerizable compound, and comprises at least the following (A), (B) and (D), or (C) and ( A transparent plastic material characterized in that it has a dyeable scratch-resistant coating obtained from a coating composition comprising component D). (A): HO―(CH ₂ )― _n OH or HO―(CH ₂ CH ₂ O)― _o
A precondensate of at least one diol selected from H [m and n are both integers of 2 to 6] and a colloidal dispersion of finely divided silica. (B): Methylolmelamine in which part or all of the methylol groups are alkyl etherified. (C): Precondensate of the above (A) and (B). (D): Solvent. The transparent plastic material in the present invention is preferably a plastic lens, but is not limited thereto, and may be used for window materials, windshields, optical elements, and other materials of automobiles. Particularly preferred plastic lenses are those used for eyeglasses. As mentioned above, CR-39 polymer is particularly preferred as the plastic, but other polymers may also be used. CR-39 polymer is a homopolymer or copolymer of CR-39 monomer (diethylene glycol bisallyl carbonate);
Copolymers containing CR-39 as a main component, ie, those obtained from monomer mixtures in which the proportion of CR-39 monomers in all monomers is 50 mol % or more, are preferred.
In addition, compounds that can be copolymerized with CR-39 monomers are not limited to styrene, methyl methacrylate, and other monomers having α,β-unsaturated groups, but include unsaturated polyesters, other oligomers, and prepolymers. Good too. CR-39
It may also be in the form of a pressed polymer that has been polymerized to some extent. CR-39 polymer is obtained by curing a mixture of CR-39 monomer and a compound that can be copolymerized with it using a polymerization catalyst or radiation. The CR-39 polymer may contain additives, such as photochromic compounds, and may be laminated with other transparent materials. The transparent plastic material having the scratch-resistant coating of the present invention can be easily dyed with conventional dyeing solutions, and good dyeability can be obtained. Dyeing primarily colors the scratch-resistant coating, but also transparent plastic materials may also be colored through this coating. In order to improve the dyeability of the scratch-resistant coating, the type of polyhydric alcohol used in the raw material coating composition and its precondensation method are important factors, as described below. The coating composition for forming the scratch-resistant coating according to the present invention will be explained below along with the contents of the coating composition according to the invention of the earlier application. Hitherto, coating compositions have been known in which organosilicon compounds such as tetraalkoxysilanes and alkyltrialkoxysilanes and their hydrolysates are added to alkyl etherified methylolmelamine and polyhydric alcohols (Japanese Patent Application Laid-Open No. 126264/1983). Public notice,
(See Japanese Patent Application Laid-Open No. 101235, etc.). However, the hydrolysates of these organosilicon compounds have a floc-like appearance and the density of silica is low. Moreover, it is difficult to completely hydrolyze, and alkoxy groups tend to remain. Further, in an organosilicon compound having an alkyl group such as an alkyltrialkoxysilane hydrolyzate, the alkyl group remains. Furthermore, it differs from particulate silica in that it has fewer silanol groups, which are thought to be involved in the reaction. For these reasons, hydrolysates of organosilicon compounds do not sufficiently improve the hardness of scratch-resistant coatings. On the other hand, the hydrolysis reaction of organosilicon compounds is a slow reaction, requiring 1 to 10 days for preparation, and the resulting dispersion lacks stability and is prone to sedimentation. Colloidal dispersions of finely divided silica solve all of the above problems. Particulate silica is usually approximately spherical particles of 20 to 500 Å, and is an inorganic silica obtained mainly by preparing water glass by an ion exchange method or the like. This particulate silica is available as a stable colloidal dispersion in water or an organic solvent. Commercially available colloidal dispersions of fine-grained silica are said to be produced by an ion exchange method using water glass as a raw material, and it is preferable to use this colloidal dispersion of fine-grained silica in the present invention. Of course, it is not limited to those obtained by this manufacturing method, and for example, those manufactured by a dialysis method using water glass as a raw material and others can be used. The particle size of the finely divided silica is preferably 20 to 500 Å, more preferably 50 to 250 Å. As the particle size increases, the transparency of the scratch-resistant coating tends to decrease, and as the particle size decreases, the hardness tends to decrease. Moreover, this silica colloid is said to have 3 to 4 silanol groups per 100 square angstroms. As a dispersion medium,
Water, alcohol, toluene, organic solvents such as 1,4-dioxane, etc. can be used, and organic solvents are particularly preferred. Water is mainly used as the dispersion medium for commercially available colloidal dispersions of finely divided silica, but in order to turn this into an organic solvent dispersion, solvent replacement is performed. For example, it is possible to add a water-miscible organic solvent to an aqueous dispersion and remove water by ultrafiltration, etc., or to mix an aqueous dispersion or an organic dispersion obtained by the above method with a dispersion medium. A method may be used in which a dispersion medium with a higher boiling point is added and replaced with the desired dispersion medium by distillation or the like. Particularly preferred dispersion media include methanol, ethanol, isopropanol, butanol, 2-ethoxyethanol, etc., which have carbon atoms of 1 to 1.
4, and isopropanol is the most suitable. The polyhydric alcohol to be precondensed with finely divided silica is HO-(CH ₂ -) _n OH or HO-(
Diols selected from CH ₂ CH ₂ —O—) _o H (m, n=2 to 6) are preferred. If trihydric or higher alcohols are used, the dyeability will be significantly reduced, resulting in secondary or tertiary alcohols.
When a polyhydric alcohol having a grade alcohol group is used, the surface hardness decreases. When polyhydric alcohols having groups other than alkylene groups and ether groups are used, the color tone of the dyeing will be CR-
It is different from that of the 39 lens. Furthermore, if a polyhydric alcohol with m and n greater than 6 is used, the hardness of the coating film will decrease and the adhesive strength will also decrease. Further, when the polyhydric alcohol has an ether group in its main chain, when n is 7 or more, the dyeing speed becomes significantly faster than that of CR-39 lenses, and at the same time, the water resistance decreases. Therefore,
HO―(CH ₂ ―) _n OH or HO―(CH ₂ CH ₂ ―O――)
_o H (m, n=2 to 6) diol is optimally used, and at least polyhydric alcohols are substantially the only ones used. If the diol falls within this range, whether it is used alone or in a mixture of two or more types, there is no big difference in coating hardness and dyeability of the coating, and there is no practical problem at all. Specific examples of these diols include ethylene glycol,
Examples include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, and tetraethylene glycol. A coating film is formed using a coating material consisting of a simple mixture of these diols and fine-grained silica, a mixture of methylolmelamine in which some or all of the methylol groups are alkyl etherified, or a precondensation product of these three. When formed, it has low water resistance, low adhesion, and low surface hardness, and when the same dyeing material is used, the dyed color is significantly different from that of CR-39 lenses. Therefore, by using a precondensate obtained by reacting these diols with the silanol groups of particulate silica, all of the above problems were solved. The reaction between the diol and the silanol group of the finely divided silica can be carried out without a solvent after distilling off the dispersion medium of the finely divided silica, or by using a secondary or tertiary alcohol with a boiling point of 100°C or higher, or a secondary or tertiary alcohol with an active functional group such as an alcohol group. It is obtained by reacting for 2 to 15 hours, preferably for 2 to 6 hours, in a solvent without water, at a temperature ranging from 100° to the boiling point of the diol or solvent, preferably from 130°C to the boiling point of the solvent or diol. Examples of such solvents include cyclohexanol, diacetone alcohol, toluene, xylene, chlorobenzene, and the like. To accelerate this reaction, add 0.1 to 5% by weight of an acid such as phosphoric acid or p-toluenesulfonic acid, preferably 0.2 to 5% by weight based on the solid content.
May be added at 1.0 weight percent. Methylolmelamine is a compound obtained by reacting melamine and formaldehyde, and may include a partially condensed compound. Methylolmelamine is a compound containing 1 to 6 methylol groups, and preferably one whose main component is methylolmelamine containing 3 to 6 methylol groups. Also in the case of condensed methylolmelamine obtained by precondensing melamine and aldehyde, one containing three or more methylol groups is preferable. Alcohols used for alkyl etherification of methylolmelamine include methanol, ethanol, n-, or i-propanol, n-, i-propanol,
An alcohol having 1 to 4 carbon atoms such as ``-'' or t-butanol is used. The alkyl etherified methylolmelamine is preferably methyl etherified or ethyl etherified, and the condensed methylolmelamine is preferably propyl etherified or butyl etherified. A part of the methylol group may be alkyl etherified, but preferably all of the methylol group is alkyl etherified. The most preferred alkyl etherified methylolmelamine is hexakismethoxymethylmelamine. Other examples of methylolmelamine that have been methyl etherified include the following. Hexamethylol melamine pentamethyl ether, hexamethylol melamine tetramethyl ether, pentamethylol melamine pentamethyl ether, pentamethylol melamine tetramethyl ether, pentamethylol melamine trimethyl ether, tetramethylol melamine tetramethyl ether, tetramethylol melamine trimethyl ether, trimethylol melamine Trimethyl ether. The proportion of the colloidal dispersion of alkyl etherified methylol melamine, diol, and finely divided silica is not particularly limited, but it should optimize the hardness, dyeability, adhesion, water resistance, and other properties of the scratch-resistant coating. There is a certain preferable range for this. The ratio of alkyl etherified methylolmelamine and diol is 1:0.5 to 1:0.5 in gram equivalent ratio.
1:2 is preferred. The gram equivalent ratio is expressed as the ratio of the number of alkyl ether groups and methylol groups in the alkyl etherified methylol melamine to the hydroxyl groups of the diol. The weight ratio of the diol to the solid content of the colloidal dispersion of finely divided silica is preferably 1:0.6 to 1:4. If the amount of alkyl etherified methylol melamine used exceeds this range, film forming properties will improve, but the hardness of the coating film will tend to decrease, and if it is below this range, dyeability and water resistance will tend to decrease. be. Furthermore, if the amount of silica exceeds this range, the hardness improves, but cracks due to heat tend to occur during the formation of the scratch-resistant coating, and if the amount is below this range, sufficient hardness is often not obtained. The coating composition in the present invention may be a mixture of a precondensate of particulate silica and diol and an alkyl etherified methylol melamine, but preferably a mixture of a precondensate of particulate silica and a diol and an alkyl etherified methylol melamine. It is precondensed. Precondensation of both is performed at ectotherm.
The reaction is carried out at 130°C, preferably in the presence of an acid catalyst.
The degree of precondensation is such that when this precondensate is dissolved in isopropanol to give a solid content concentration of 60 wt%, the viscosity is 50 to 20,000 cp (centipoise), preferably 300 to 3,000 cp. If precondensation is not performed, there is a risk that the appearance of the film will deteriorate or whitening will occur. However, the difference between the two is not so great that a good scratch-resistant coating with almost the same performance can be obtained even without this precondensation. Various solvents can be used to dissolve the coating composition. For example, methanol, ethanol, n- or i-propanol, n-butyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, diacetone alcohol, toluene, benzene, N,N-dimethylformamide, etc. be. Moreover, two or more types of these solvents and other solvents can be used in combination. Further, in order to improve drying properties, ethyl acetate, acetone, methyl ethyl ketone, and other low boiling point solvents can be added. Other ingredients may be added to the coating composition of the present invention. Particularly preferred is the addition of a catalyst that promotes the reaction of the alkyl etherified methylol melamine with the diol.
As this catalyst, those used as curing accelerators for melamine resins can be used, and these are effective for the above reaction. For example, examples of the catalyst include ammonium chloride, ammonium nitrate, ammonium thiocyanate, phosphoric acid, p-toluenesulfonic acid, and almolsulfonic acid. The amount used is preferably in the range of 0.01 to 2% by weight based on the total organic solids in the coating composition. The coating composition of the present invention can be applied to transparent plastic materials by conventional application methods such as spraying, dipping, brushing, roller coating, spinner coating, and the like. After applying the coating composition to a CR-39 lens or the like in this manner, it is heat cured at a temperature range of 80 to 150°C, more preferably 100 to 130°C for 15 minutes to 4 hours, more preferably 30 minutes to 2.5 hours. By doing so, it is possible to obtain a coating film with good surface hardness, good dyeability, good adhesion, and good transparency. The thickness of the coating film is preferably 0.5 to 20μ, more preferably 2 to 10μ. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited by these Examples. Furthermore, the evaluation of film properties was as follows. Steel wool test; sliding distance 5cm,
Abrasion test using #001 steel wool at a sliding speed of 35 reciprocations/min and a load of 300gr. Dyeing speed: Place the sample in a dyeing tank containing CR-39 water dispersion dye for lenses, and heat at 85℃5.
It is expressed as the light transmittance after minutes. Dyeing tint: The sample was placed in the same dyeing tank as above and observed at 85°C for 5 minutes, aiming to determine the difference in tint with the CR-39 lens. Adhesion: The tape used was (Nichiban's cellophane tape), which was tested with cross-cut tape at 1 mm intervals. Examples 1 to 6 Isopropanol dispersion of spherical silica with an average particle size of 110 Å ^*1 (Silica content 30 wt%) 100 parts (same below weight parts) After mixing 30 parts of the diol listed in Table 1, isopropanol as a dispersion medium was removed. 0.3 part of phosphoric acid was added to this mixture, and the mixture was reacted at 150°C for 4 hours. This reaction product was mixed with hexakismethoxymethylmelamine at a gram equivalent ratio of 1:1 to the diol, and isopropanol was added so that the total solid concentration ^*2 was 60 wt%. While methanol and isopropanol are distilled off at 150° C., isopropanol is simultaneously added from the outside so that the total solids concentration in the reaction system is always 60 wt%. I got it. A CR for eyeglasses with a diameter of 65 mm is prepared by degreasing the surface of a composition containing 100 parts of this prepolymer, 100 parts of diacetone alcohol, 0.6 parts of p-toluenesulfonic acid as a catalyst, and 0.3 parts of a leveling agent.
39 lenses using a spinner method so that the film thickness after drying was 3 μm, and then heated and dried at 120° C. for 1.5 hours, and the physical properties of the resulting coating film were measured. Results first
Shown in the table. Further, the results of Examples 7 to 13, Reference Examples, and Comparative Examples 1 to 7 below are also shown in Table 1. *1: Obtained by adding isopropanol to a silica colloid dispersion obtained by desalting a water glass aqueous solution using an ion exchange resin and removing water by distillation. *2: Here, the solid content refers to the weight assuming that all the functional groups of the diol and the alkyl etherified methylolmelamine have reacted and the dealcoholization reaction has been completed. Examples 7-8 The same test as in Example 1 was conducted except that the weight ratio of silica and diol was changed. Examples 9-10 The same test as in Example 1 was conducted except that the silica particle size was changed. Examples 11 to 13 Using the same raw materials, usage amounts, and method as in Example 1, a mixture of silica and diol precondensate, hexakismethoxymethylmelamine, and isopropanol (total solid concentration 60 wt%, viscosity approximately 50 to 80 cp) was prepared. Manufactured. Without further precondensing this mixture, the same amounts of diacetone alcohol, p-toluenesulfonic acid, and leveling agent as in Example 1 were added to 100 parts of this mixture to prepare a composition, which was then used in the same manner as in Example 1. I conducted a test. Reference example Evaluation results of CR-39 lens without scratch-resistant coating. Comparative Example 1 Same composition as Example 1, but without precondensation of silica and diol. Comparative Example 2 A method similar to Comparative Example 1, except that methyltriethoxysilane was hydrolyzed instead of silica. Comparative Examples 3 to 7 The same tests as in Example 1 were conducted using polyhedral alcohols other than the diols of the present invention.

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Claims (1)

[Scope of Claims] 1. A transparent plastic material comprising a homopolymer of diethylene glycol bisallyl carbonate or a copolymer with a copolymerizable compound, comprising at least the following (A), (B) and (D), or
A transparent plastic material characterized in that it has a dyeable scratch-resistant coating obtained from a coating composition comprising components (C) and (D). (A): HO―(CH ₂ )― _n OH or HO―(CH ₂ CH ₂ O)― _o
A precondensate of at least one diol selected from H [m and n are both integers of 2 to 6] and a colloidal dispersion of finely divided silica. (B): Methylolmelamine in which part or all of the methylol groups are alkyl etherified. (C): Precondensate of the above (A) and (B). (D): Solvent. 2. The material according to claim 1, characterized in that the transparent plastic material is a lens for spectacles.