RU2522604C2 - Laser-sensitive polymer coatings - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to laser-sensitive polymer coatings for recording information with high resolution on hydrophilic and hydrophobic surfaces of substrates of a various chemical nature. A coating is made of a composition, which includes the following components: poly(o-hydroxyamide) as a polymer binding agent, sensitive to laser radiation, nigrosin dye as a laser-sensitive substance, an amide solvent. Poly(o-hydroxyamide) represents the product of polycondensation of isophthalic acid dichloride with 3,3'-dihydroxy-4,4'-diaminodiphenylmethane or isophthalic acid dichloride with mixture of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane with bis-(3-aminopropyl)dimethylsiloxane, taken in a molar ratio from 10.0:1.0 to 1.0:10.0. The coating is obtained by application of the composition directly on a substrate surface without its preliminary dressing. After that, it is subjected to drying at 100-120°C for 15-30 min.

EFFECT: invention makes it possible to obtain coatings, stable in time, resistant to impact of vapours of HCl, H₂SO₄, HNO₃, petrol, alcohol, ammonia, water and withstanding thermocyclic loading from -50 to +200°C.

Description

The invention relates to the production of laser-sensitive polymer coatings for recording high-resolution information (at least 4000 dpi) on hydrophilic and hydrophobic surfaces of various chemical nature (lavsan and polyimide films, metals, crystals, etc.).

Known multilayer laser-sensitive coatings [US No. 7371443; US No. 7311954], including the adhesive and laser-sensitive layers. The material consists of two layers of acrylate films of various colors - adhesive, colorless and colored. The information is applied to the film by burning the upper colored layer using CO ₂ or a solid-state laser. Laser engraving provides high font contrast and high image quality. The films are resistant to temperature extremes from -50 to + 300 ° С, are resistant to abrasion, UV radiation, and aggressive chemical environments.

A significant drawback is that the acrylate adhesive layer does not have sufficient adhesion to a number of polymer films, for example, mylar film. In addition, the laser-sensitive layer in these films is thick, so the print resolution is about 20-30 dpi, which is not enough to print microtext.

Laser-sensitive materials are known not in the form of coatings, but when the laser-sensitive substance is introduced directly into the polymer mass. They are obtained by mixing organic dyes or carbon black with a granular polymer using special pressure mixers [US No. 5576377].

Monolayer laser-sensitive coatings on a substrate based on styrene-acrylic copolymers and substances sensitive to laser radiation are known, for example, a mixture of ammonium sulfate, ammonium ortho-phosphate and sucrose encapsulated in a polymer matrix [WO 2006/063165; US No.20100233447]. As monomers for the synthesis of the polymer binder, (meth) acrylic acid, (meth) acrylamide, (meth) acrylonitrile, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethyl (meth) acrylate, glycidyl methacrylate, acetoxyethyl methacrylate, dimethyl amino-ethyl methacrylate and diethyl amino-ethyl acrylate.

The main significant drawback of such coatings is insufficient strength, since it is impossible to achieve 100% conversion of monomers during the polymerization reaction.

Laser-sensitive coatings are also known, including oxygen-containing transition metal salts, preferably molybdenum, chromium or tungsten oxide, as a laser-sensitive component [WO 07/012578; US No. 7485403; US No. 8048605]. Such a system, consisting of laser-sensitive oxygen-containing transition metal salts, may also contain an additive selected from the group of organic acids, polyoxy compounds and bases, for example tartaric acid, citric acid are used. Examples of polyhydroxy compounds are sucrose, gum arabic and meso-erythritol. This coating has the disadvantage that inorganic metal salts practically do not dissolve in organic polymer binders; in the manufacture of these coatings, the combination of several components is required, which can lead to uneven thickness of the formed coating and, as a result, to lower resolution during laser engraving.

Closest to the proposed coating are laser-sensitive coatings based on compositions comprising a polymer binder, a laser-sensitive substance and a solvent, the coating containing titanium dioxide in the form of anatase encapsulated in the polymer and a polymer binder of various chemical nature: styrene-acrylic copolymers, epoxies, polyamides, etc. [Campbell, J., et al. / US No. 201110065576; US No. 6429889; EP No. 2181163 B1].

A significant and obvious drawback of this coating is that the process of obtaining compositions for such coatings is very time-consuming: it requires careful fractionation of titanium dioxide particles by size, selection of conditions for encapsulating titanium dioxide particles, and the study of the compatibility of encapsulated particles of a laser-sensitive substance with a polymer binder.

The technical problem and a positive result of the inventive laser-sensitive polymer coatings is the use of compositions comprising a high-strength heat-resistant polymer - poly (o-hydroxyamide) and a dye that is sensitive to laser radiation at a wavelength of 1.06 μm (fiber laser power 20 W, pulse repetition rate 0.8-1.0 MHz , pulse energy 0.01-0.1 mJ).

The essence of the invention is new laser-sensitive coatings, which consist of polymer binders - high-strength heat-resistant poly (o-hydroxyamides) - polycondensation products of iso-phthalic acid dichloride with 3,3'-dihydroxy-4,4'-diamino-diphenylmethane or iso-phthalic dichloride acids with a mixture of 3,3'-dihydroxy-4,4'-diamino-diphenylmethane with bis- (3-aminopropyl) dimethyl-siloxane in an amide solvent - and nigrosin dyes.

The polycondensation reaction of isophthalic acid dichloride with 3,3'-dihydroxy-4,4'-diamino-diphenylmethane or with a mixture of 3,3'-dihydroxy-4,4'-diamino-diphenylmethane with bis (3-aminopropyl) dimethyl -siloxane is carried out in amide solvents, and the molar ratio of amines is selected in the range from 10.0: 1.0 to 1.0.:10.0. Poly (o-hydroxyamide) after completion of polycondensation is mixed with a solution of the corresponding nigrosin dye in an amide solvent and used after filtration to coat the surface of the substrate. After application, the coating is dried at 100-120 ° C for 15-30 minutes, while choosing the following ratio of components, wt.%:

Poly (o-hydroxyamide) 18-24 Nigrosin dye 0.9-2.4 Amide solvent rest

A positive effect of the invention is the creation of adhesion-resistant single-layer coatings with a thickness of 3.0-5.0 μm, with high adhesion to the hydroxyl and hydrophobic surfaces of various substrates, including polyimide or highly hydrophobic lavsan films. Under the action of a laser with a wavelength of 1.06 μm (fiber laser power 20 W, pulse repetition rate 0.8-1.0 MHz, pulse energy 0.01-0.1 mJ), a high-resolution image (≥4000 dpi) with a contrast of at least 0.8 in reflected light is obtained.

The main distinguishing features of the claimed invention are that:

- proposed new polymeric binders, high-strength heat-resistant poly (o-hydroxyamides) - polycondensation products of isophthalic acid dichloride with 3,3'-dihydroxy-4,4'-diaminodiphenylmethane or with a mixture of 3,3'-dihydroxy-4,4 ' -diaminodiphenylmethane with bis- (3-aminopropyl) dimethyl-siloxane;

- a new type of laser-sensitive additives - nigrosin dyes;

- the components that form the laser-sensitive coatings form a molecular solution in an amide solvent, which eliminates the additional operation of encapsulating the dye and, therefore, reduces the complexity of the process;

- a polymeric binder - poly (o-hydroxyamide) - is not obtained in the process of creating a composition with a laser-sensitive component, but a solution of poly (o-hydroxyamide) with certain viscosity parameters is used, which ensures stability of the properties of the obtained composition and the parameters of the formed coating;

- coatings have high adhesion to lavsan, polyimide film, metals, crystals and other substrates, are stable in time, resistant to the effects of HCl, H ₂ SO ₄ , HNO ₃ , gasoline, alcohol, ammonia, water and can withstand thermal cyclic loads from - 50 up to + 200 ° С. The composition of the composition is selected so that the mechanical properties of the films used correspond to the properties of the corresponding substrate;

- coatings allow recording information with a resolution of at least 4000 dpi with a contrast of at least 0.8 in reflected light when exposed to a laser with a wavelength of 1.06 μm (fiber laser power 20 W, pulse repetition rate 0.8-1.0 MHz, pulse energy 0.01-0.1 mJ.) .

Example 1. 1 g-mol of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane is dissolved in 11.2 g-mol of dimethylacetamide containing not more than 0.035% moisture at room temperature. The solution is cooled to -5-0 ° C and 1.0 g mol of carefully ground isophthalic acid dichloride is added to the cooled solution with stirring over 5-7 minutes so that the temperature of the reaction mass does not rise above 40 ° C. After adding the entire amount of isophthalic acid dichloride, the cooling is removed and the reaction mass is kept at room temperature for 2 hours, then cooled again to -5-0 ° C and 2 g of freshly distilled epichlorohydrin are added dropwise over 15-20 minutes, after which the solution is stirred at room temperature for 60 minutes The kinematic viscosity of the polymer solution is 690 mm ² / s, the reduced viscosity of a 0.5% solution of poly (o-hydroxyamide) precipitated in a mixture of solvents: chloroform-diethyl ether, taken in a volume ratio of 5: 1, in concentrated sulfuric acid is 0.89 dl / g

Example 2. The polycondensation reaction is carried out analogously to example 1, but take a mixture of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane and bis- (3-aminopropyl) dimethyl-siloxane in a molar ratio of 10: 1. The viscosity of the reaction varnish solution is 300 mm ² / s.

Example 3. The polycondensation reaction is carried out analogously to example 1, but take a mixture of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane and bis- (3-aminopropyl) dimethyl-siloxane in a molar ratio of 1: 7. The viscosity of the reaction varnish solution is 60 mm ² / s.

Example 4. The polycondensation reaction is carried out analogously to example 1, but take a mixture of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane and bis- (3-aminopropyl) dimethyl-siloxane in a molar ratio of 1:10. The viscosity of the reaction varnish solution is 30 mm ² / s. The solution is very liquid and when diluted with an amide solvent to dissolve the dye, the viscosity decreases so much that it is impossible to form a film of the required thickness.

Example 5. Preparation of the composition. 50 g of a poly (o-hydroxyamide) reaction solution (polymer solids content 24%) is mixed with a solution of alcohol-soluble nigrosine Nigrosine Alcohol Soluble (5% by weight of dry polymer) in an amide solvent. The mixture is stirred at room temperature, filtered and centrifuged (2000 rpm) is applied to a fixed polyester film. The coated lavsan film is dried at 100-120 ° C for 15-30 min, and then subjected to laser irradiation (wavelength 1.06 μm, fiber laser power 20 W, pulse repetition rate 0.8-1.0 MHz, pulse energy 0.01-0.1 mJ ) When exposed to laser radiation, a resolution of at least 4000 dpi is achieved with a contrast of at least 0.8 in reflected light.

Example 6. Carried out analogously to example 2, but take 7.5% of the dye in relation to the dry residue of poly (o-hydroxyamide). Image parameters are similar to example 2.

Under the conditions of Examples 5-6, the resolution and contrast of a laser image in a layer deposited on a lavsan were investigated with a dye-poly (o-hydroxyamide) ratio of less than 5% and more than 10%. With a lower dye content, the laser-sensitive layer is not sufficiently contrasted, with more than 10% by weight of the dry polymer, a part of the dye does not dissolve and must be carefully filtered.

Thus, the proposed laser-sensitive coating allows you to form a single-layer adhesive and mechanically strong coating on substrates of various chemical nature, which can be used to record information on various types of surfaces, including highly hydrophobic polymer films for use in various fields of technology.

Claims (1)

Laser-sensitive polymer coatings, including a polymer binder, a laser-sensitive substance and a solvent, characterized in that the polymer binder uses high-strength heat-resistant poly (o-hydroxyamides) - polycondensation products of isophthalic acid dichloride with 3,3'-dihydroxy-4,4 '-diaminodiphenylmethane or isophthalic acid dichloride with a mixture of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane with bis- (3-aminopropyl) dimethylsiloxane, taken in a molar ratio from 10.0: 1.0 to 1.0: 10.0, as a laser sensitive substances use nigrosin dyes and an amide solvent, and the coating is applied directly to the surface of the substrate without preliminary dressing, it is dried at 100-120 ° C for 15-30 minutes, and the following ratio of components in the composition is selected, wt.%:
Poly (o-hydroxyamide) 18-24 Nigrosin dye 0.9-2.4 Amide solvent rest