SI23875A - Hard coatings based on metal alkoxides - Google Patents

Abstract

Hard coatings based on alkoxides solve the technical problem of abrasion resistance of plastic materials by performing hard coatings applied in thin coatings to the surface of abrasion-resistant plastic materials in order to provide greater abrasion resistance and longer material life. Subject of the invention are new solid coatings from organo-inorganic hybrid nanocomposites with mixed metal (Si-, Zr, A1-) oxide inorganic phases. The nanocomposites are characterized by high surface hardness, good abrasion resistance, good optical permeability and solubility of the precursor in various organic solvents. The rigid coatings according to the invention were prepared by different methods which differ in terms of the content of the metal alkoxide. Our goal was to achieve the highest surface hardness of the resulting hybrids.

Description

SOLID COATS BASED ON METAL ALCOXIDES

FIELD OF THE INVENTION

Coatings, surfaces made of plastic materials.

A technical problem

A technical problem solved by the invention is the abrasive non-existence of plastic materials.

The state of the art

Abrasion-resistant coatings, including hard coatings, have been used for decades to protect various substrates from scattering. The earliest coatings were used for the protection of plastics. plastic lenses, etc. Although many methods have been proposed in the past for the synthesis of hard coatings and the protection of substrates, it has been shown that most coatings have only a minimal increase in the surface resistance of the substrate. Many other methods are those that are very impractical to produce coatings or use as coatings, or require a very high cure temperature.

One of the last established methods is the production of solid coatings with gas deposition of inorganic materials such as S1O2, ZrO, etc. per substrate. A disadvantage of this method is its high cost and manufacturing limitations (vacuum chamber required). There were restrictions on the size and shape of the substrates.

Inorganic coatings are disclosed in US patents 272768909 and US3460956. The first discloses hydrolyzed hafnium, zircon and titanium based coatings applied in a thin layer (1 micron) to the substrate and crosslinked under the influence of air moisture. The second discloses the manufacture of a solid coating based on tetraalkine titanate in solvent, water and nitric acid. Water and acid are required for the hydrolysis of titanate.

The most recent attempts to protect substrates with hard coatings are disclosed in US2481809, US3575998, US3632715. They disclose the production of organic-inorganic coatings by a sol-gel process in an organic binder. Patent US3324055, US3642681, US3708225, and US3817905 are reported to have similar fabrication.

US3324055 discloses the manufacture of a coating based on a reactive organic polymer and an inorganic fully hydrolyzed polymer containing so many monomers that, after application, they can crosslink or polymerize. condense.

US3642681 describes the preparation of an abrasion-resistant coating to protect the PMMA plastic surface. The coating is made of hydrolyzed tetraalkyl orthosilicate and organic acid. After application, the coating hardens within 100 to 180 ° C for 30 minutes to 5 hours.

US3708225 discloses a method of coating a soft substrate with an abrasion-resistant coating. The method contains 3 phases of thin film deposition and curing.

US3817905 describes the manufacture of an effective zinc, silane, water and acid based coating.

Patents US4073967 and US4042749 describe a method of coating a substrate with an abrasion-resistant coating based on reactive silanes and metal esters. Water catalysis is not used. Coatings can be cured by both thermal and UV polymerisation. Coatings are corrosion resistant and chemical resistant.

Recent methods include the application of coatings based on inorganic nanoparticles (SiC> 2, T1O2, ZrO, etc.) and organic binders as described in patents and patent applications, for example WO2011028075, W02010062436, US2005266208, JP2003183577.

Description of the new solution

Alkoxide-based hard coatings solve the technical problem described above by applying hard coatings applied in thin coatings to the surface of abrasion-resistant plastic materials in order to provide greater abrasion resistance and longer material life.

The subject of the invention are new hard coatings from organic-inorganic hybrid nanocomposites with mixed metal (Si-, Zr, A1-) oxide inorganic phases. The nanocomposites are characterized by high surface hardness, good abrasion resistance, good optical transmittance and precursor solubility in various organic solvents. The hard coatings according to the invention have been prepared by different processes, which differ depending on the metal alkoxide content. Our goal was to achieve the best surface hardness of the resulting hybrids.

Solid coatings were synthesized by a sol-gel process based on precursors 3 (trimethoxysilyl) propyl methacrylate (MAPTMS) and transition metal alkoxides, preferably zirconium (IV) alkoxide (ZrAO) and aluminum (III) alkoxide (A1A0), using catalysts, aqueous ranges of inorganic acids and bases (HCl, NH4OH, HNO3 ...). Despite the high reactivity of the metal alkoxides, they did not need to be protected by chelating agents such as organic acids (acetic acid) and diketones (ethylacetoacetate). Additional experiments in various solvents, such as ethanol, methanol and butyl acetate, have shown that THF plays a key role in this, and the inorganic product was dropped immediately after the addition of the metal alkoxide and was abandoned. The content of a metal alkoxide in a mixture of the reactants (Wz _RA ⁼ rnzrAo / (mzrAO oimaptms +)) was 28, 47, 61 and 72% and is higher than that reported in the literature.

The viscous fluid of the nanocomposites was then used as a hard coat on acrylic glass, polycarbonate and ABS / PMMA. The application was performed by spraying with preliminary surface cleaning. They were hardened by thermal and photo polymerization. The Taber test determined the abrasion resistance of the applied coatings with different ZIP and AIP content and compared the obtained values with the abrasion resistance of various organic binders, which are otherwise used for the preparation of hard coatings.

The abrasion resistance results showed that the abrasion resistance of the nanocomposites according to the invention is higher compared to the commercial hard coatings used as an additive to increase the abrasion resistance of parquet lacquers.

The hard coatings according to the invention have been prepared by different processes, which differ depending on the metal alkoxide content. Our goal was to achieve the best surface hardness of the resulting hybrids. Such Zr and Al hybrids are, among other things, useful for hard coatings on softer substrates, especially plastics.

A typical process for preparing a hard coating is presented in Figure 1. First, MAPTMS was diluted in THF and an equivalent amount of catalyst (0.1 M HCl) was added to the mixture while stirring at room temperature to give hydrolysis expired. After 5 min and during constant stirring, a specially prepared solution of metal alkoxide in THF was added dropwise (15 min) and stirred further. Already in the first phase, all the necessary amount of catalyst was added to catalyze both precursors of both MAPTMS and metal alkoxide. The mass ratios of the reactants and the solvent are shown in Table 1. The metal alkoxide content of the reactant mixtures (W _ZrA o = not _ZrA0 / (m _ZrA0 + himaptms)) was 20, 33, 43 and 50% and is higher than reported in the literature.

Table 1: Preparation of Zr-MAPTMS hard coatings.

Coating mark Reactants Solvent ™ MAPTMS (g) M _ZrA o (g) ITlTHF (g) 0.20 Zr-MAPTMS 20 5 100 0.33 Zr-MAPTMS 20 10 100 0.43 Zr-MAPTMS 20 15 100 0.50 Zr-MAPTMS 20 20 100

After the reaction has taken place, i.e. after condensation was completed, the solid coating under reduced pressure was removed with solvent and excess water. We obtained high-viscous products, which were further used as for hard coatings. hard coatings.

Thin coatings were prepared from solutions of hard coatings in butyl acetate, ethyl acetate, xylene and other solvents by applying them to the spray gun spray, pouring, dipping and spin coating, preferably with SATA JET RP spray gun. Substrates (PMMA) were pre-purified with EtOH and plasma etching. In cases where the coatings were cured under UV light, 1 - 10% of the commercial photo-initiator, preferably 4% of the Irgacure 184 initiator, was added to the solutions, while 0.1 was added to the solutions in the cases when the coatings were thermally cured. -5% commercial azo or initiator feathers, preferably 1% AIBN. The coatings were first dried in an air oven for 60 min at 60-80 ° C to allow the solvent to evaporate and then solidified. The films were thermally cured in an air oven (30 min at 150 ° C), and UV curing was carried out with commercially available 250W iron UV radiation (3 min with 250 W radiation power).

Hereinafter, the object of the invention is further explained by means of drawings, the drawings forming part of the application and representing:

Figure 1 shows the preparation process of Zr-MAPTMS hard coating.

For Akripol d.d.

Claims (6)

PATENT APPLICATIONS Claims 1. Alkoxide-based hard coatings, characterized in that their synthesis is carried out by a sol-gel process based on the precursors of 3- (trimethoxysilyl) propylmethacrylate (MAPTMS) and transition metal alkoxides, preferably zirconium (IV) alkoxide (ZrAO), and aluminum (III) alkoxide (A1A0), with the aid of catalysts, the aqueous range of inorganic acids and bases. 2. Hard coatings according to claim 1, characterized in that the MAPTMS is diluted in THF and an equivalent amount of catalyst, preferably O, 1M HCl, is added to the mixture during constant stirring at room temperature to proceed hydrolysis, further to allow the mixture to elapse after time. , preferably for about 5 minutes and, while stirring constantly, dropwise, preferably for about 15 minutes, a specially prepared metal alkoxide solution, preferably ZrAO in THF, is added. Hard coating according to any one of the preceding claims, characterized in that a thin coating is prepared therefrom, which is cured under UV light, adding 1 to 10% of a commercial photo-initiator, preferably 4% of the Irgacure initiator, to the hard-coating solutions. 184. Hard coating according to claim 3, characterized in that the thin coating is cured with iron UV radiation, preferably of a power of 250 W, preferably for a duration of 3 minutes. Hard coating according to claim 1 or 2, characterized in that a thin coating is prepared therefrom, which is thermally cured, adding 0.1-5% of commercial azo or initiator feathers to the hard coating solutions, preferably 1 % AIBN. A hard coating according to claim 5, characterized in that the thin coating is cured in an air furnace, preferably for 30 minutes at 150 ° C.