DE2522241A1 - Coating compsn for acrylic resin articles, e.g. lenses - contg silane derivs., alkali metal and/or zinc naphthenate and acetic acid - Google Patents

Abstract

A coating compsn. esp. for acrylic resin articles e.g. optical lenses comprises: (a) 10-40 wt. %, based on compsn. of a material obtd. by partially hydrolysing in water at 50-80 degrees C, for 1-10 h, a cpd. chosen from (1) a trialkoxy-silane of mula R'Si(OR")3 (I) where R' is 1-4C alkyl, phenyl or vinyl and R" is 1-4C alkyl, (2) co-condensation prods. of (I) and 1-40 wt. % phenyl- or vinyl-trialkoxysilane with 1-4C alkoxy, (3) co-condensation prods. of 1 mole of (I) and 0.05-1 mole tetraalkoxysilane with 1-4C alkoxy, and (4) co-condensation prods. of (I) and 0.05-1 mole dialkyl-dialkoxysilane with 1-4C alkyl and alkoxy; (b) 0.05-5 wt. %, based on (a) of alkali metal- and/or Zn naphthenate; (c) 5-30 wt. % based on compsn. acetic acid and (d) solvent(s) which is inert w.r.t. (a) and (b) and pref. chosen from alcohols, ketones ethers and arom. hydrocarbons. The compsn. pref. has a viscosity of 10-30 cps. The compsn. forms a hard coating and is resistant to fading solvents and stress cracking.

Description

Coating agents The invention relates to agents that after application Form a protective layer on acrylic resin objects, which, compared to others Layers that are applied to plastics, a better surface hardness, Scratch resistance, solvent resistance and resistance to crazing when subjected to stress0 In general, plastics are easily damaged and lose their shine because they have no high surface hardness and no scratch resistance or have scratch resistance.

These disadvantages are particularly serious when using the plastics used to manufacture optical products such as lenses.

In order to improve these poor properties, there are many methods suggested to the surface of the plastic body with organic siloxane compounds to coat and to harden the coating in order to form a protective layer on the plastic body to build. However, these known methods do not give satisfactory protective layers.

For example, the protective layers or coatings that are after the known processes are produced so brittle that they are tested for their abrasion resistance to improve, easily crack. If one tries on the other hand, their persistence to improve against crazing, their abrasion resistance becomes inferior. The known coating solutions also have too short a pot life and can do so not be used for long periods of time.

The present invention is based on the object of a coating composition to create a. on the surface of acrylic resin bodies or articles Protective layer with very good surface hardness, scratch resistance and solvent resistance and resistance to crazing under stress.

The. The invention relates to a coating composition which contains (1) a partially hydrolyzed siloxane compound, (2) one or more alkali metal and / or zinc salts of naphthenic acid, (3) acetic acid and (4) other organic solvents.

This mass contains the components in suitable proportions.

The agent is applied to the surface of acrylic resin objects and hardened. The coated acrylic articles have excellent properties like surface hardness, Scratch resistance, solvent resistance and resistance to stress crazing.

The invention is a coating solution that essentially consists of (a) 10 to 40 wt / a, based on the total weight of the coating agent, a partially hydrolyzed siloxane compound, which by hydrolysis at least one of the following compounds in water at 50 to 800 g for 1 to 10 hours is obtained: (1) a hydrocarbon trialkoxysilane of the formula R'Si (OR ") 3 ' wherein R 'is an alkyl group having 1 to 4 carbon atoms, a phenyl or vinyl group and R "represents an alkyl group having 1 to 4 carbon atoms, and / or (2) co-condensation products of (1) and 1 to 40% by weight of a phenyl- or vinyl-trialkoxysilane, in which the alkoxy group Contains 1 to 4 carbon atoms, and / or (3) co-condensation products of 1 mole of (1) and 0.05 to 1 mole of tetraalkoxysilane in which the alkoxy group has 1 to 4 carbon atoms contains, and / or (4) co-condensation products of 1 mole of (1) and 0.05 to 1 Moles of dialkyl-dialkoxysilane in which the alkyl and alkoxy groups have 1 to 4 carbon atoms contain, (b) 0.05 to 5 parts by weight per 100 parts by weight of component (a) one or more salts, namely alkali metal salts of naphthenic acid and / or zinc salts of naphthenic acid, or a mixture of these salts, (c) 5 to 30% by weight, based based on the total weight of the coating agent, acetic acid and (d) the remainder an inert one organic solvent for components (a) and (b) or a mixture of these Solvent.

The new coating compositions according to the invention have a long pot life The new coating agents can be applied to the surface of acrylic resin articles and cured to form a coating layer which, as mentioned above, has significantly improved properties.

The coating agents or coating solutions can be applied directly to the surface of acrylic resin articles by any commonly used coating method and at a temperature of about 80 ° to about 100 ° C hardened to evaporate the solvents contained therein and to cause a condensation reaction.

The coating compositions according to the invention contain (1) a partial hydrolyzed siloxane compound or a product of esohydrocarbon trialkoxysilanes of the formula R'Si (ORt1) 3, (2) one or more alkali metal and / or zinc salts of Naphthenic acid, (3) acetic acid and (4) one or more organic solvents, which are compatible with components (1) and (2).

The hydrocarbon trialkoxysilanes (1) are multifunctional siloxane compounds of the formula R1Si (0R1?) 3, in which R 'is an alkyl group with 1 to 4 carbon atoms, represents a phenyl, vinyl group and other functional groups and R represents an alkyl group means having 1 to 4 carbon atoms.

Methyltriethoxysilane is preferred.

A partially hydrolyzed product of hydrocarbon trialkoxysilanes is, as described in U.S. Patent 3,451,838, obtained by adding water to hydrocarbon trialkoxysilanes and the resulting material at a Heated temperature of 50 to 800C for 1 to 10 hours.

In the present invention, the hydrocarbon trialkoxysilane can be used with 1 to 40 wt. One or more organic silane compounds are mixed as with phenyl or vinyl trialkory (C1-C4) silanes, and this mixture can be used either water or mineral acids such as hydrochloric acid are added and heated, whereby the partially hydrolyzed co-condensation product is formed.

A partially hydrolyzed co-condensation product which is essentially 1 mole of the hydrocarbon trialkoxysilane as the main component and 0.05 to 1 mole Contains tetraalkoxy (C1-C4) silane as an additional component, forms a train with improved hardness.

A partially hydrolyzed co-condensation product of 1 mole of hydrocarbon trialkoxysilane and 0.05 to 1 mole of dialkylr -Cq) dialkoxy (-C4) silane forms a soft coating.

When a hydrocarbon trialkoxysilane wherein R 'is a vinyl group means, is used as a component of the co-condensation product, increases the Silane the adhesion of the resulting layer to the acrylic surfaces.

By properly selecting the components that are in the co-condensation product are used, coatings are obtained which have the desired properties.

The aforementioned partially hydrolyzed products can do less than about 5% by weight of water, based on the total weight of the hydrolyzed products, contain.

The solids concentration of the partially hydrolyzed co-condensation products determines the coating weight of the protective layer on the surface of the acrylic body is formed.

The coating weight in turn determines the physical properties the shift.

A higher solids concentration results in a higher coating weight the layer which has excellent hardness and excellent scratch resistance but is so brittle that it easily cracks if you bend it.

On the other hand, a lower solids concentration gives a lighter one Coating weight of the layer, and the layer has insufficient scratch resistance, to give a product suitable for practical use.

The suitable coating weight of the agent according to the invention depends on the acrylic resin article to which the agent is applied. A lot from 2 to 6 g / m2, expressed as solids, applied on the acrylic resin article, is best for acrylic sunglass lenses.

So that a layer is obtained that is in the aforementioned amount (2 to 6 g / m2) is present, it is preferred to immerse the acrylic article in the coating solution and then the article out of the coating solution at a speed from 10 to 40 cm / min to remove the coating layer on the article Form, the coating solution has a viscosity of 10 to but and contains 10 up to 40% by weight of the partially hydrolyzed product, calculated as solids.

The properties of the applied layer can vary greatly, depending on the type of catalyst or catalysts used in the coating agent will.

It has been found that a coating agent is obtained which has a has a longer pot life than known coating agents if one uses metal salts of the Naphthenic acid used as catalysts. It was further found that such coating agents of the applied layer have excellent properties impart in terms of scratch resistance and crazing resistance under stress, properties that somewhat compete with each other.

The term "naphthenic acid" as used in the present application and used in the claims means the general term for monocarboxylic acids of naphthenic hydrocarbons present in crude mineral oils, where the acids have the formula R "'(CH2) nCOOH, in which R11t is a cyclic nucleus, which consists of one or more rings, for example a cyclohexane ring, a cyclopentane ring and its alkylated cyclic nuclei in general, and in which n is an integer from 1 to 14.

The carboxylic acid group is connected to the ring core (R "') via methylene (-CH2-) n groups tied together. The simplest and most typical acid, in which n is 1, is cyclopentane acetic acid.

Naphthenic acid is a mixture of non-separable organic acids with 7 to 20 carbon atoms and a cyclic nucleus. The naphthenic acid, dise is used is accordingly a mixture of compounds of those given above Formula.

Acceptable metal salts of naphthenic acid are alkali metal and zinc salts, and one of these salts or one can be used in the coating compositions according to the invention Use a mixture of these. Other metal salts do not give a satisfactory catalytic one Effect in relation to the coating agent.

The metal salts of naphthenic acid used according to the invention are in an amount of 0.05 to 5 parts by weight per 100 parts by weight of the partially hydrolyzed Hydrocarbon trialko »Silane product or co-condensation product used.

If the salts are used in an amount below 0.05 parts by weight, so they are not effective and do not cause a satisfactory curing reaction in the coating agent.

On the other hand, when the salts are used in an amount exceeding 5 parts they escape from the inside onto the surface of the applied layer.

The catalysts cause the coating agent to slow.

or mild hardness, a property that makes the excellent hardness and scratch resistance and also good adhesion and resistance to crazing the applied layer results. The catalysts also cause the Solution from the coating agent is very stable.

The catalysts dissolve very well in the solvents for the partially hydrolyzed products from hydrocarbon alkoxysilanes and their Co-condensation products.

According to the invention it is also important that the coating agent acetic acid contain. The acetic acid must be in an amount of 5 to 30 wt.%, Based on the Total weight of the coating agent. The acetic acid acts as a solvent and also causes the coating layer to adhere firmly to the surface of the acrylic resin article adheres.

The acetic acid is also effective in preserving the pot life of the coating solution for long periods of time and still prevents the applied Solution shows any start-up features.

The acetic acid prevents the acrylic resin body from being affected the solvent will form hairline cracks, which is otherwise easily the case with the acrylic items come into contact with alcohol.

If the acetic acid is added in an amount above 30%, it remains part of it back after the agent has cured under normal conditions; this creates an unpleasant odor. On the other hand, if the acetic acid is in a Amount below 5S6 is used, the resulting layer is insufficient Adhesion.

Glacial acetic acid is preferred, but technical grade acetic acid can can also be used.

The other organic solvents in addition to acetic acid are not critical and they can be used under known solvents selected for partially hydrolyzed siloxane compounds and naphthenic acid salts are like alcohols, ketones, ethers and / or aromatic hydrocarbons. To the Of these solvents, ethanol is used to produce the coating agent for acrylic bodies and isopropyl alcohol especially because of their boiling points and solvency preferred. The amount of the other organic solvent must be sufficient to the partially hydrolyzed compound and the naphthenic acid salt together with the Acetic acid to completely dissolve and to reduce the concentration of the partially hydrolyzed Compound to 10 to 40% by weight, calculated as solids and based on total weight of the coating agent.

In order to coat acrylic resin bodies with the agent according to the invention, you can use any methods such as immersion, spray and flow or fluidized bed coating and use similar procedures. The acrylic resin bodies thus coated are then heated to cure the siloxane resin (the partially hydrolyzed compound). This hardening can be carried out at a temperature which is much lower is than the temperature as commonly used.

Since the hardening temperature is higher, the shorter the hardening time it is preferred to cure the applied layer at a temperature which is as high as possible but lower than the heat distortion temperature of the Acrylic resin. In general, it is preferred at 80 to 1000C for 2 to 40 Hours to harden.

The following examples and comparative examples illustrate the invention.

For example, 1 to 4 water becomes a solution of methyltriethoxysilane given in ethanol. The mixture is heated at 75.degree. C. for 3 hours and then at 1450.degree further heated to distill off the azeotropic mixture of alcohol and water, whereby a partially hydrolyzed condensate solution is obtained, which is about 50 wt. Contains partially hydrolyzed siloxane compound and those in the following table I is referred to as component (a). The solution is then diluted with n-butanol.

Sodium naphthenate, identified in Table I as component (b) is dissolved in a portion of the glacial acetic acid called component (c) whose total pre-calculated amount is given in Table I. The solution the components (b) and (c) is then partially hydrolyzed to that previously described Condensate / n-butanol solution given.

The resulting solution is made by adding n-butanol, as required, further set so that they contain the three components (a), (b) and (c) in the table I contains specified amounts. Coating solutions are obtained.

Injection molded optical lenses made from methyl methacrylate resin be good with a degreaser and then with cleaning fluids flushed and then immersed in the coating solutions described above and with a Gescht.rindixeit taken from 30 cm / min. The coated lenses are then placed in an oven 95 0C and left in it for 16 hours so that the coating layer can harden.

The coated lenses thus obtained are examined and the Adhesion, pencil hardness, scratch resistance (abrasion with steel wool) and the resistance to crazing when exposed to stress.

In addition, the pot life of the coating solutions is determined, using an accelerated pot life test. The results obtained are listed in the table.

The physical properties of the coated lenses, how they shown in Table I were determined as follows.

1. Adhesion The layer applied to each of the lenses is with a sharp one. Blade cross-hatched, with ten horizontal and ten vertical lines with 1 mm spaces between the lines.

A cellophane tape is then stuck onto the cross-hatched Lines of the lens glued on and sharp at a 900 angle to the applied one Layer peeled off.

This procedure is repeated three times. The adhesion thus obtained is divided into five classes from A (no delamination) to E (complete Delamination), depending on the extent to which the layer has been peeled off.

2. Pencil hardness' A pencil hardness device, a so-called pencil hardness Tester that determines the hardness of paints, varnishes and similar materials is used to determine the hardness of the applied layer. A pencil core, that on the applied surface of a lens sample with a T angle of 450 to the surface was about 3 mm forward with a load of 1.0 + 0, Q5 kg and a speed of 0.5 mm / sec. The test results are given as the minimum hardness of the pencil core of the applied layer damaged in these conditions.

3. Scratch resistance (steel wool abrasion test) The coated Surface of the lenses was rubbed with a steel wool pad. The results were rated according to the following three categories, depending on the extent in which the surface was scratched: A = no scratches even if the surface was rubbed heavily with the steel wool pad; B = slightly scratched when the surface rubbed with steel wool; C = slightly scratched if the surface is moderate was rubbed with the steel wool, 4. Resistance to crazing Stress lens samples with a diameter of 80 mm were placed between the clamp and given the compression cell under load on an INSTRON testing machine. The samples were compressed continuously at a speed of 20 mm / min, until their surface showed crazing; at that time the were applied Stress and stress recorded. The resistance to crazing under stress was rated as follows: excellent (A) = no crazing even if the permanent set exceeds 12.5%; good (B) = no hairline cracking when the permanent set is 5 to 12.5%; bad (C) = hairline cracking if the permanent deformation is less than 5%.

5. Pot life A coating agent is placed in a test tube, which is then closed, and left to stand in a hot water bath at 50 0C. The coating agent in the test tube is observed at intervals, and there will be cloudiness, whitening, consistency, gelation and similar characteristics rated. In Table I, the pot life is given as the number of hours during which the agent shows no gel formation.

Comparative Examples 1 to 6 Coating agents are as described above but the amounts of components (b) and (c) are as shown in Table I set as described. In Comparative Example 6, sodium acetate is used instead of Component (b) used.

These comparative coatings are applied to the surface of lenses as applied in Examples 1 to 4 above, cured in the same way and the same properties are determined. The test results are shown in Table 1 Tabel I example below Coating agent See Ex. Component (a) component (b) component (c) sodium acetate [solid conc. [Parts by weight [conc. (%), [Parts by weight, rel.

(%)] per 100 parts based on d. to 100 parts of comp. (a)] total mass] of comp. (a)] Ex. 1 15 2.5 15 -2 30 0.2 21 -3 35 1.4 21 -4 35 5.0 21 -Comp.Ex.1 30 - - -2 30 1.7 - -3 30 - 18 -4 30 1.7 3 -5 30 2.5 35 -6 30 - 18 1.7 Comments: Component (a) = partially hydrolyzed methyltriethoxysilane condensate solution component (b) = sodium naphthenate component (c) = acetic acid Table I (continued) E.g. u. Test results See Ex. Adhesion, pencil hardness, scratch resistance, pot life Remarks resistance to (accelerated hairline cracking of the test) Stress Ex. 1 A 5H A A -2 A 6H A A 72 3 A 7H A A 72 4 A 7H A A - See Ex. 1 E 2B C C -2 D 2B B B -3 B H @ C -4 C 4H-5H B B -) some vinegar-5 A 5H-6H A A - ) like odor 6 A 7H A A 48)

Claims (5)

Claims 1. Coating solution, which consists essentially of (a) 10 to 40% by weight, based on the total weight of the coating agent, one part hydrolyzed siloxane compound obtained by hydrolysis at least one of the following Compounds in water at 50 to 800 C for 1 to 10 hours is obtained: (1) a hydrocarbyl trialkoxysilane of the formula R'Si (OR ") 3 'where R' is Alkyl group with 1 to 4 carbon atoms, a phenyl or vinyl group and R " denote an alkyl group having 1 to 4 carbon atoms, and / or (2) co-condensation products of (1) and 1 to 40% by weight of a phenyl or vinyl trialkoxysilane in which the alkoxy group Contains 1 to 4 carbon atoms, and / or (3) co-condensation products of 1: tol of (1) and 0.05 to 1 mole of tetraalkoxysilane in which the alkoxy group has 1 to 4 carbon atoms and / or (4) co-condensation products of 1 mole of (to (1) and 0.05 bis - moles of dialkyl-dialkoxysilane, in which the alkyl and alkoxy groups have 1 to 4 carbon atoms contain, (b) 0.05 to 5 parts by weight per 100 parts by weight of the component (a) one or more salts, namely alkali metal salts of naphthenic acid and / or zinc salts the naphthenic acid, or a mixture of these salts, (c) 5 to 30% by weight, based to the total of the coating agent, acetic acid and (d) the remainder an inert one organic solvent for components (a) and (b) or a mixture of these Medium solution. 2. Coating agent according to claim l, characterized in that it is -k e n n z e i c h n e t that there are solvents (d) alcohols, ketones, ethers and / or aromatic Contains hydrocarbons. 3. Coating agent according to at least one of the preceding claims, in that it has a viscosity of 10 to 30 cP. 4. coating agent according to at least one of the preceding claims, in that it is methyltriethoxysilane as component (a) and contains sodium naphthenate as component (b). 5. Process for producing a surface coating on acrylic resin articles, by applying the coating solution to the objects according to at least one of claims 1 to 4 applies in an amount of 2 to 6 g coating solution, calculated as solids, per m2 surface of the acrylic resin object, and then heated the coated article to 80 to 100C for 2 to 40 hours, to harden the coating.