CS234516B1 - An aqueous dispersion coating composition for flexible synthetic sheet materials - Google Patents

Abstract

BACKGROUND OF THE INVENTION The present invention relates to improving the processing properties of aqueous dispersion coating compositions for poromers and other flexible synthetic sheet materials. The coating composition according to the invention contains 0.3 to 16 wt. a poly acrylate thickener, 0.05 to 0.3 wt. % ammonia, 0.7 to 1.3% by weight of casein, 1.5 to 11% by weight of casein; pigment, 1 to 5% (non-ionic surfactant by weight, two of the non-irradiated polymeric binders, including acrylate-butadiene copolymer, thermoreactive acrylate-styrene copolymer, copolyacrylate and polyurethane, wherein the two polymer binders, in a weight ratio of 1: 4 to 4: 1, optionally, melamine-formaldehyde precondensate, waxes and water The coating composition may comprise casein and pigment preferably in the form of a cassein pigment preparation in which the dry matter is comprised of 9 to 30% % by weight of the casein and 91 to 70% by weight pigment, which is prepared by dispersing and homogenizing pigments and optionally fillers in a colloidal alkaline aqueous solution of casein with additives such that the resulting solution has a concentration of 30-60% by weight.

Description

The invention relates to an aqueous dispersion coating for the surface treatment of flexible synthetic strip materials, in particular polyurethane-based poromers.

Treatment systems for flexible sheet materials can be solvent-based, but also classic - water-dispersion. For poromeric synthetic leathers, a combination of both types is very often used. In this case, the colored base layer of the surface treatment is created by applying water-dispersion coatings in one or more often in multiple layers. A solvent-based system of finishing coatings is applied on top of it.

In a continuous production process, in addition to the final application properties, the processing properties of the finishing systems for the individual layers of the surface treatment are equally important. The aim of the selection of components and the final formulation of the finishing systems must be risk-free, reproducible production.

Water-dispersion coatings formulated on the basis of aqueous dispersions of suitable polymer binders are complicated colloidal systems, the stability of which is to a large extent sensitive to external conditions, e.g. during preparation and processing on coating machines. The most common are:

- a roller coating machine for applying the main portion of the weight of the colored coating material;

- a spray machine used to cover frequent defects from roller application - grooves, air bubbles, etc. - and for final equalization of the color shade.

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- To create a high-quality colored base layer of surface treatment, it is necessary for the coating material to exhibit optimal processing properties. The most important processing properties include:

- perfect mechanical and electrolytic stability

- stability against separation of pigment mixtures

- good flowability

- low foaming

- possibility of regulating the weight of the coating on a given coating device.

Processing properties affect the quality of the applied coating and can therefore significantly affect the useful properties of the surface treatment. With regard to the final quality of the colored coating and the economy of production, the basic processing properties of the coating material for the above types of coating equipment are associated with the issue of spreading, i.e. the creation of a continuous, smooth, even layer of wet coating material.

The flowability of the coating material is an important requirement for achieving even application and optimal coating weight, especially in continuous production conditions. This quality parameter includes two basic aspects:

and - interfacial properties, i.e. the mutual interaction between the surface of the treated substrate and the surface of the applied coating layer;

b - flow properties expressed by Theological characteristics, which require a more detailed analysis.

Water-dispersion coating systems have the character of non-wet liquids. They are characterized by a significant structural viscosity, which means that the viscosity values are to a greater or lesser extent dependent on shear stress or shear rate.

The viscosity value measured at a selected shear stress or shear rate is referred to as apparent viscosity.

An important rheological characteristic of structurally viscous systems is the value of the so-called resting viscosity; this means the value of the viscosity that the coating system reaches in the vicinity of zero.

234,516 shear stress - that is, at the moment when the system passes through the application device and is spread onto the substrate.

However, in many systems it can be observed that creep occurs only after a certain value of shear stress ^r ^ _Q - Vzv« is exceeded; this property of a liquid system is called plasticity.

Thixotropy is one of the rheological anomalies that can sometimes significantly affect the course and quality of application, especially the flowability (layering) of the applied material. In this case, the viscosity of the system depends not only on the shear rate, but also on time - with the time of application of constant shear stress, the viscosity decreases.

When evaluating the parameters of coating systems for coating, mechanical components must also be taken into account: elasticity of the liquid system, tensile strength and ductility of the fiber drawn from the liquid system.

The elasticity value of the liquid system is mainly related to the resistance to dripping. The high elasticity and ductility of the fiber cause the fibers of the coating material to be pulled out of the slit of the application roller. In this respect, coatings with low values of static viscosity are more advantageous, because they do not allow the formed fibers to be fixed on the substrate.

There are some contradictions regarding the relative importance of the interfacial and the theological aspects. However, it is generally stated that it is primarily the theological aspects that control the application phase when coating substrates. For example, the formation of a wet film is influenced by the viscosity value in the area of relatively low shear stresses in any application method - roller application, knife application, spraying, brushing or combined - in the range of relatively low shear stresses. The value of the resting viscosity can be an indicator here. The formation of a wet film, the good quality of which is a prerequisite for the implementation of single-layer covering coatings, depends simultaneously on the ability to spread and layer and on the resistance to the formation of defects in the wet coating - air bubbles, striations and other damage.

- 4 ·

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Systems with a significant structural viscosity, or with a thixotropic character or with high yield point values are advantageous for application to highly absorbent materials (e.g. textiles); after application, their resting viscosity increases to very high values, the system loses fluidity and thus prevents penetration into depth or the decorative print retains perfect sharpness of contours.

For low-absorbent substrates and for full-surface applications, including for the surface treatment of synthetic leather, systems with opposite theological characteristics are more suitable - β low structural viscosity, low resting viscosity, no thixotropic effect and low yield point values.

Water-based dispersion paints for basic color layers contain a large number of components with specific effects. The basic component here is polymer binders in the form of aqueous dispersions, most often based on polyacrylates, polyurethanes, copolymers of acrylates with other monomer components, e.g. with butadiene, acrylonitrile, styrene, vinyl acetate, etc. These paints also contain inorganic and/or organic pigments, dyes and special auxiliaries for adjusting the useful and/or processing properties; these include, for example, surfactants, crosslinkers, defoamers, viscosity regulators, substances for adjusting the feel, etc.

Coating materials for the basic color layer of the surface treatment of poromers are therefore complex and sensitive colloidal systems, their stability decreases with an increase in the number of components.

To achieve optimal performance properties of the surface treatment, it is often necessary to use mixtures of two or more polymer binders. Coloring components introduce a certain proportion of surfactants into the system and, in addition, they can sometimes themselves affect the rheological characteristics of the coating. Thickeners are most often polyacrylate due to their high efficiency - they do not have to be used in excess, so they do not have a negative effect on the absorption values and do not increase the rigidity of the polymer film.

-/234 516

However, rheologically, they are usually characterized by extreme structural viscosity and an infinitely high value of rest viscosity - plasticity. The complexity of the system is increased by other components such as crosslinkers, surfactants, stabilizers, waxes, silicone compounds and others.

The interaction of individual components in such complicated systems results in the formation of supramolecular structures that influence the properties of the continuous medium: the cohesive force of the system increases, the rheological characteristics change. The properties of these systems are not additive and, given the number of components, they cannot be predicted. The mutual behavior of the components can even be anomalous to the extent that the real properties and behavior of the system differ significantly from theoretical assumptions.

In terms of rheological characteristics, these coating materials are systems that have:

- relatively pronounced structural-viscous character, i.e. rapid viscosity gradient with increasing shear stress, which is expressed by relatively high values of the tangent of the angle and flow index values;

- very high values of static viscosity;

- viscoplastic character with limited fluidity and yield strength;

- in some formulations, especially depending on the type of polymer binder and pigment preparation, thixotropic behavior, in some cases a hint of rheopexy;

- relatively high values of ductility and tensile strength.

The unfavorable flow properties of these coatings are further aggravated in relation to the quality of the coated substrate or when using a certain application method. The almost compact, closed polyurethane surface of the untreated poromeric material is characterized by an exceptionally low surface energy value, sometimes referred to as the critical surface tension of the solid surface, which is around 27 mN.m*^. For comparison, for polyethylene, which is described as a particularly hydrophobic material, this value is around 31 mN.m“\ In view of the unavailability of surface-

234,516 active substances to achieve such low surface tensions in a liquid system and given that the influence of interfacial phenomena is quite suppressed at the real consistency of the coatings used, then the demands for favorable rheological characteristics of coatings are justified.

The consequences of unfavorable flow properties in current water-dispersion coatings for the surface treatment of synthetic poromeric leather are;

For roller application:

- A high value of the static viscosity does not allow for sufficiently fast healing of defects in the wet layer, caused by the "buoyancy" of solid particles or the scoring of the squeegee. The imperfect quality of this layer requires an additional leveling layer, usually by spraying»

- The relatively low dry matter content does not allow, under current operating conditions, to achieve the weight of the paint layer that would be required to create single-layer covering layers»

For alternating application:

- Paints have a lower dry matter content, but have a relatively higher content of polyacrylate thickener than in roller application. When passing through the nozzle of the spray gun, the paint is subjected to high shear stress, so that in this phase it has a relatively low apparent viscosity, which is a prerequisite for fine particle dispersion. During flight, the atomized particle loses part of the liquid phase by evaporation, which increases the dry matter content in the droplet;

The interaction forces in the coating material increase and thus its structural-viscous character. After impact on the substrate, the high shear stress disappears, the viscosity value increases significantly, down to the resting viscosity, so that very unfavorable conditions arise for the spreading of drops and their joining into a continuous, even layer.

Particularly unfavorable, anomalous behavior of coatings containing mixtures of certain types of water-dispersible polymer binders has been observed. For example, using a mixture of a polydiaperse binder of acrylate-butadiene copolymer with a monodisperse copolymer

- > 234 516 acrylate-styrene with strong groups were so unfavorable during spraying that it was not possible to create ^a perfectly even layer. In this case, the flow characteristics were most likely adversely affected by differences in the geometric arrangement of the solid phase of both aqueous dispersions. Although the useful properties of the surface finish of this binder mixture were satisfactory and their use would be more economically advantageous, this mixture could not be implemented in the coating material due to the unmanaged processing properties.

It has now been found that there are substances which can advantageously change the processing properties of a liquid colloidal system applied as a coating.

The unfavorable processing properties of previously known coatings for the surface treatment of flexible synthetic strip materials, especially polyurethane-based poromers, are significantly improved in the water-dispersion coating according to the invention.

The essence of the invention lies in the fact that a coating based on polyacrylates and/or their copolymers or mixtures with other acrylates, with butadiene and/or styrene, containing pigments, Darviva, thickeners, surfactants, defoamers and other coating additives, contains 0.3 to 16¾ wt. of polyacrylate thickener, 0.05 to 0.3 wt. % ammonia, 0.7 to 1.3 wt. % casein,

1.5 to 11% by weight of pigment, 1 to 5% by weight of nonionic surfactant, further two from the group of mutually incompatible polymer binders, including acrylate-butadiene copolymer in an amount

2.3 to 13.8 wt. %, thermosetting acrylate-styrene copolymer in an amount of 4.6 to 14 wt. %, copolyacrylate in an amount of 2 to 10 wt. % and polyurethane in an amount of 2 to 3.2 wt. %, wherein the selected two polymer binders are in a weight ratio of 1:4 to 4:1, further optionally 0.002 to 0.2 wt. % defoamer, 0.4 to 0.9 wt. % melamine formaldehyde precondensate and 0.4 to 0.7 wt. % waxes, with the remaining proportion up to 100 wt. % of the coating composition being water. This coating composition preferably contains casein and pigment in the form of a casein pigment preparation, in which the dry matter consists of 9 to 30 wt. % casein and 91-70 wt. % pigment, and which is prepared by dispersing and lyophilizing pigments and optionally fillers in a colloidal alkaline aqueous solution of casein with additives such that the resulting solution has a concentration of 30 to 60% by weight.

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The following indicators are used to quantitatively describe the processing properties of the coating material according to the invention:

The line showing the dependence of viscosity (or shear rate) on shear stress in logarithmic coordinates makes an angle of 0° with the axis of shear stress values, and the tangent of this angle indicates the rate of decrease in viscosity (or shear rate) with shear stress, i.e. indicates the severity of the structural-viscous character of the coating material.

The value of the rest viscosity was determined from the given logarithmic dependence by extrapolation to the zero value of shear stress.

The yield stress - the value of shear stress at which the system creeps - was determined from the graphical dependence of the shear rate on the shear stress as the intersection of the ascending linear part of this dependence with the shear stress axis.

In practice, the structurally viscous character of a system is often expressed using the flow index - it is the ratio of the apparent viscosities measured at lower and higher shear rates, usually in the ratio of 1:10 or 1:20. To calculate the flow index, the apparent viscosities measured with a Brookfield RVT viscometer at speeds of 1 and 10 rpm». ¹ of the measuring spindle were used.

The severity of the thixotropic character was assessed from the area of the hysteresis loop, which was created when measuring the dependence of shear rate on shear stress from zero value to maximum and back within a defined time program.

The mechanical properties of coating systems for coating flat materials were used to determine the values of ductility and tensile strength. The tensile strength of the liquid column was determined on a íAi Nouy apparatus used to measure surface tension. A circular plate mounted on a torsion wire was used to measure the tensile strength. The force required to tear the plate from the surface of the coating was determined by the weight of the weight required to balance the plate back to its original position.

To determine the ductility, the Jansson principle was used: a metal plate was placed exactly on the surface of the material being tested.

- 4,234,516 paint, moved with a uniform strong pull upwards. A fiber was formed between the plate and the surface of the paint and its length in mm was determined at the moment of rupture.

When investigating the influence of modification components on the processing properties of coatings, a coating without modification was first prepared. Casein as a modification component was then added to the coating used for the basic color layer of the surface treatment of poromers and applied on a roller machine. The consistency of all coatings (according to ČSN 673 013) was adjusted using a polyacrylate thickener and ammonia water to a value of approximately 20 s. The following quantities were determined: angle//, value of the resting viscosity, comparative apparent viscosity and value of the flow index.

1^0 and the flow limit value (2^·

Table 1 shows the effect of these substances on the monitored rheological parameters.

Table I

Casein content (% wt.) £gnzieten- rheological quantities (degrees) 7, (mPaS) ^0 (mPaS) yes (dyn.cm) - 20.8 74 10880 1,14.10 ⁹ 5.74 47.5 2.5 20.6 38 1860 6.84.10 ³ 2.82 19.5 6.3 20.4 26 920 1.62.10^ 1.92 13.5

From the comparison of the values of the angle o4 , the rest viscosity /7 and the yield stress 6Γ _θ it follows that casein exhibits a significant effect on suppressing the pseudoplastic character of the flow and on reducing the values of ^ ₀ , even at a relatively low concentration in the system· ή!) 234 516

Casein belongs to the group of high-molecular proteins - proteids. The macromolecular chain contains peptide groups on which, under the action of, for example, formaldehyde, or substances containing methylol or N-alkoxymethylol groups, or under the action of other substances, cross-methylene -CJ^- bonds are formed; this results in fixation and suppression of the solubility of the casein film.

In an alkaline environment, casein dissolves and forms a colloidal solution. It is quickly subjected to the decomposition effect of bacteria, so the solutions must be preserved. The most commonly used organic compounds are parachlorometacresol, nitrobenzene, phenol, and^.

Casein forms relatively hard films; its applicability in coating systems intended for coating flexible sheet materials such as poromeric leathers is therefore limited. When optimizing the casein content in binder mixtures used in these coatings, changes in the values of the initial tensile modulus of elasticity Εθ and the wettability values of polymer films were monitored depending on the composition of the polymer binders, the casein content and the degree of crosslinking - fixation.

It has been found that in coatings for the surface treatment of flexible sheet materials, it is possible, depending on the composition of the coating system, to add up to 15% of casein dry matter, based on the total dry matter of polymer binders in the coating, without negatively affecting the quality of the surface treatment.

It has also been found that casein can be added in various forms. The basis of all of them is an aqueous alkaline colloidal solution of casein with a preservative. This may contain other auxiliaries, such as waxes, plasticizers, leather glue, surfactants and possibly other. Particularly advantageous is a casein pigment preparation prepared by dispersing and homogenizing inorganic or organic pigments, optionally with some inorganic fillers, such as barium sulfate or aluminum hydroxide in an aqueous alkaline colloidal solution of casein with preservatives and containing the other auxiliaries mentioned.

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To optimize the casein content, a casein solution with β additives was used. It was found that to suppress adverse interactions and to achieve significant changes in the mechanical properties and rheological characteristics of the coating, it is necessary that the content be higher than 5% by weight of casein dry matter, based on the total dry matter of polymer binders in the coating. It was further found that casein acts as a modifying component in coatings that contain mixtures of polymer binders of various properties and are used in different proportions (ratio) so significantly that the processing properties of the modified coatings are very similar.

With regard to production economics, the use of casein pigment preparations is particularly advantageous because it is possible to combine two technological operations: the casein pigment preparation acts as a coloring agent and simultaneously as an effective modifier.

The effectiveness of pigment preparation in coatings with particularly pronounced internal interactions is demonstrated by the results shown in Table II on the following page.

Two different mixtures of polymer binders were used to prepare the coatings:

Mixture A - butyl*acrylate-acrylonitrile copolymer with acrylate-butadiene copolymer in a weight ratio of 1:1

Mixture B - thermosetting acrylate-styrene copolymer with acrylate-butadiene copolymer in a weight ratio of 1:1.

Pigments used:

P - pigment in the shade of ochre - iron oxides

S - a mixture of pigments in the shade ocher * brown - iron oxides.

Modification systems used:

KPP - casein pigment preparation

K + P - casein solution + pigment

KP+ P - casein solution with additives ♦ pigment

The modification systems are further specified in the individual examples.

-4l> 234 516

VI (B VI -P* UJ year H CK 0 Ό what About B th ω what 00 5» t_i. h ax Η·Κ< what < B About Ό H· bi bi ω ω bi bi Φ about c+ 1 with MS W MS IV B TJ + T7 about About •th + bi 1 < Oy bi ffu p. 3 about W 1 /-»<+ fV H IV H H H ω Φ about CO CO About Ό CO 00 3 w 40 40 40 40 40 about N oh IV IV year About 00 ro H· ω t OK year IV year UJ VI Qj SE UJ -4 about -4 IV (D 40 40 04 40 About I-* About About about About H c+ 40 40 40 40 40 «0 04 00 see UJ -4 IV 00 IV IV -in OK 00 from-> VI H UJ and year OK \O VI 4*· year 00 4* About A About -Ρ» C04 about about About About About about • VI H UJ & To H UJ CO fd 00 00 -4 -4 •Ρ» about Uf Γ4Ν okay in Okay OK 00 WHAT About about About About —4 about regards H IV H UJ φ- H w M 40 <0 w 40 H Ό who H 00 about H About 00 about IV -4 year 00 o. UJ H (In «< about -V 1 1 IV year 0 40 40 4· * about In/ About About VI about about Q ' B v-z about about about bi 40 40 1 1 40 M & H -4 00 CO 0 . About Ό H ~4 H knows About 1 year CO OK OK 00 40 40 1 1 40 «0 tv> About About H (3 _

Table IIí Summary values of properties of unmodified and casein-modified coatings

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In the case of polymer binder mixture B, stronger interactions between components can be confirmed, which are expressed by a very high value of the resting viscosity as well as other mechanical values and rheological characteristics; these are so unfavourable in this case that the coating material containing this binder mixture cannot be applied, for example, by spraying. A relatively small addition of casein modifier achieved a significant suppression of internal structures and thus an increase in the mobility of the layers, an improvement in the flow properties and flowability of the coating material after application to the treated substrate. As a modifying additive, casein also has the ability to completely eliminate the thixotropic character and further improve the flow of the coating material in the area of very low shear stresses by suppressing the flow limit. Casein _further reduces the mechanical values; the liquid fiber loses its elasticity and, especially during roller application, the coating material is better separated from the application roller and transferred to the coated substrate.

The use of casein in the coating has other beneficial consequences. The dried coating layer with casein has a hydrophilic character; this clearly improves the wettability of this layer and the flowability of further applied layers. The contact angles Φ of the coating droplets were measured on the Gontact Angle Analyzer and it was found that the values of these angles when applied to a coating layer with casein are clearly lower than when the same coating is applied to a colored layer without casein.

In multi-layer coatings, the conditions for creating a high-quality colored surface treatment layer are improved by adjusting the rheological characteristics and improving the interfacial relations.

The contribution of casein to increasing the water vapor permeability values through the polymer film is also significant. When evaluating individual films from polymer binders, it was found that the addition of casein increases the water vapor permeability values of pigmented films by 20 - 30. This creates the prerequisites for a significant improvement in the important utility property of poromerics - comfort when wearing shoes made from this material.

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The addition of casein in amounts above 11% by weight clearly increases the wettability values of the polymer film, which is negatively reflected in the low values of resistance of the surface treatment to wet abrasion.

It has been found that casein fixation can be carried out simultaneously with crosslinking of tensor-reactive polymer binders by adding compounds, e.g. with methylol or N-alkoxymethylol groups, which may optionally contain free, residual formaldehyde. For this purpose, e.g. water-soluble melamine formaldehyde precondensate is used in an amount of up to 10% by weight, based on the total weight of the dry matter of the polymer binders. The crosslinking and fixation reactions take place when the material is exposed to temperatures of 130 to 140 °C for 2 min.

The coating material according to the invention is prepared by first preparing a thickening salt from water-dispersible thickeners based on polyacrylates and from an inorganic or organic base, preferably from ammonia water; after the viscosity has stabilized, either a pigment preparation is added to the thickening salt and then an aqueous alkaline colloidal solution of casein with a preservative and other auxiliaries, e.g. with waxes, plasticizers, surfactants and others, or a casein pigment preparation is used (whereby it is possible to optionally add one of the other mentioned modifying casein mixtures to this), then an aqueous dispersion of polymer binders and the necessary auxiliaries, such as surfactants, defoamers, crosslinkers, or others, are mixed in. The optimal viscosity for the selected application method is regulated by the content of the thickening salt.

When preparing the coating, it is also possible to proceed in such a way that the thickening is carried out as the last operation without prior preparation of the thickening salt: an inorganic or organic base, preferably ammonia water, is added to the mixture after all the above-mentioned components as the last component in such an amount that the coating has a pH value of 7-10.

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The use of the modifying additive according to the invention in coatings for the surface treatment of flexible surface materials, such as poromeric and other synthetic leathers, in a continuous production process brings significant advantages in technology and production economics. Modification with casein has a very positive effect on the processing properties of coatings and allows:

- to implement formulations of coatings that contain raw materials that are economically very advantageous, but in terms of processing properties are not yet realistically usable. In this way, the range of usable raw materials can be significantly expanded, e.g. to include domestic sources;

- to combine two technological operations and functions - coloring and modification - when using casein pigment preparations;

- good quality of the deposits of modified paint create the prerequisites for simplifying the technological process of surface treatment by possibly eliminating additional equalization of the color shade by spraying.

To further clarify the nature of the invention, we present several examples of modified coatings.

Example 1 - comparative

Standard formulation of casein-free paint for roller application; presented to illustrate the effectiveness of the modification process. The consistency of the paint is adjusted using a pre-prepared thickening salt.

demineralized water polyacrylate carbonizer (40% by weight) defoamer ammonia water (25% by weight)

48.00 parts by weight 3.26 nh ₃ )

0.002

0.80 the coaling salt is left to stand for 1 hour, then the tanned pigment preparation without casein (50% by weight) 15.60 aqueous dispersion of acrylate-butadiene copolymers (46% by weight) 23.30 are added

- 1C 234 516 aqueous dispersion of butyl acrylate-acrylonitrile (40% by weight) 7.80 parts by weight non-ionic surfactant (10% by weight) 1.30 The prepared coating material is applied to the poromeric substrate on a cylindrical application device equipped with an air squeegee for additional equalization of the coating weight.

After drying, the paint layer shows defects (grooves, air bubbles, etc.) - an additional, corrective overspray must be applied. The rheological characteristics of the paint are given in Table II, line no. 1.

Example 2

Modified coating formulation for roller application; compared to Example 1, the tinted casein-free pigment preparation in the coating formulation is replaced by a casein pigment preparation in an equivalent amount. The other components remain as in the formulation of Example 1.

The modified coating material is characterized by significantly improved processing properties. The favorable change in the physical characteristics caused by the addition of casein is evident from Table II - see No. 2 in comparison with No. 1. The color coating is of significantly better quality, defects occur rarely. In the case of sufficient coverage of the color layer, additional spraying is not necessary.

Example 3 demineralized water 50 parts by weight

polyacrylate thickener defoamer (30% by weight) 2.50 0.20 T N W a tinted blend of opaque, transparent pigments (20 % wt.) 3.00 M N casein solution (18 % wt.) 5.00 H W aqueous dispersion of butyl acrylate-acrylonitrile copolymer (40 % wt.) 23.00 N H water dispersion of polyurethane (40 % wt.) 7.00 H 1« surfactant (20 % wt.) 5.00 « w wax dispersion (15 % wt.) 3.00 W

234 516 water-soluble melamine formaldehyde precondensate (60% by weight) 1.30 parts by weight ammonia water (25% by weight) amount to adjust to pH 7-8

Modification made by additional addition of casein to the preparation of opaque transparent pigments. The coating material is applied on a roller coating machine; subsequent equalization of the wet layer weight is carried out using a suitable spiral doctor blade so that the final layer weight is in the range of 60 - 80 g.m. A high-quality transparent colored layer on a suitably tinted poromeric substrate creates a brilliant semi-aniline type surface finish. For rheological characteristics, see item 3 in Table II.

Example 4

Paint formulation for a single-layer opaque color coating

demineralized water polyacrylate thickener (40% by weight) 30.64 parts by weight 2.09 parts by weight defoamer , 0.02 H 99 tinted pigment preparation 17.70 tl 99 casein-free (36 % mass) aqueous alkaline colloidal casein solution, preserved, with waxes, plasticizers (20 % mass) 6.76 19 99 aqueous dispersion of thermosetting acrylate-styrene copolymer (46 % mass) 17.90 99 99 acrylate-butadiene (46 % mass 17.90 99 99 non-ionic,surface active substance (10 % mass) 1.53 99 »9 water-soluble melamine- formaldehyde precondensate (60 % mass) 0.75 1« 99 wax dispersion (15 % mass) 4.51 « W ammonia water (25 % mass NHj) quantity to : set ing pH 8- Ί0

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The coating material is applied on a roller machine equipped with an air squeegee in an amount of 60-80 g.m . A high-quality coating of the coating material with a higher dry matter content (compared to the coating material in example 2) does not require additional correction coating by spraying. Rheological characteristics see tab. II.

Example 5

Sprayable coating material. It is applied additionally to the colored base layer created on a roller application device (see examples 1, 2).

demineralized water polyacrylate thickener ammonia water thickening salt is left undisturbed, then tinted casein pigment preparation thermoreactive copolymer acrylate - styrene copolymer acrylate - butadiene copolymer nonionic surfactant water-soluble melaine is added

(40^,% wt.) (2^6hmotoNH ₃ ) 57.70 3.70 0.90 mass 11 n parts «1 11 (44% by weight) 12.00 n n (46% by weight) 18.00 tt « (46% by weight) 6.00 11 11 (10% by weight) 1.00 11 ·» (60% by weight) 0.70 11 11 will result in thermal exposure

(130 ^w - 140 's/2min.) simultaneous crosslinking of the thermoreactive polar binder and fixation of casein.

By modifying the paint, such an improvement in the flowability of the coating is achieved that the color layer is perfectly homogeneous and color-equal.

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When applying a coating without a casein modifying component, the cohesive forces of this combination of polymer binders are so high that fine droplets do not coalesce and the resulting layer is significantly uneven in color.

The differences in the values of mechanical properties and rheological quantities are evident from Table II - rows 5, 5a; the modifying additive causes particularly significant changes in the structural-viscous characteristic - the value of the angle tk, or Ι^θ - and in the value of the rest viscosity.

The effect of the invention is most pronounced here - with this combination of polymer binders, the original rheological characteristics are so unfavorable that the coating material without modification cannot be used for spray application.

Example 6

Paint formulation for single-coat opaque color

Jl coating demineralized water polyacrylate thickener (40% by weight) ammonia water tinted pigment preparation with casein (43% by weight) water-dispersible acrylate-butadiene copolymer (46% by weight) water-dispersible thermosetting acrylate-styrene copolymer (46% by weight) non-ionic surfactant aqueous solution of melamine formaldehyde precondensate (60% by weight)

10.0 parts by weight

0.9

0.2

28.1 ,28.1

30.1

1.2

1.4

The application is carried out according to the procedure described in example 4. The rheological characteristics of the coating are given in Table II, No. 5.

Claims (2)

Water-dispersive coating material for the treatment of flexible synthetic sheet materials, in particular polyurethane poromers, based on polyacrylates and / or copolymers thereof or mixtures with other acrylates, butadiene and / or styrene, and further comprising pigments, dyes, thickeners, surfactants, defoamers and other paint additives, characterized in that it contains 0.3 to 16 wt. of a polyacrylate thickener, 0.05 to 0.3% hmox. % ammonia, 0.7 to 1.3 wt. % casein, 1.5 to 11 wt. % pigment, 1 to 5 wt. nonionic surfactants, two of the group of incompatible polymeric binders comprising an acrylate-butadiene copolymer in an amount of 2.3 to 13.8% by weight, a thermoreactive acrylate-styrene copolymer in an amount of 4.6 to 14% by weight, a copolyacrylate in 2 to 10 wt. and polyurethane in an amount of 2 to 3.2% by weight, wherein the selected two polymeric binders are in a weight ratio of 1: 4 to 4: 1, further optionally 0.002 to 0.2% by weight. % antifoam, 0.4 to 0.9 wt. % of melamine formaldehyde precondensate and 0.4 to 0.7 wt. % of waxes, the remainder being up to 100 wt. Paints are water. 2. A water-dispersive coating composition as claimed in claim 1, comprising casein and a pigment in the form of a casein pigment preparation in which the dry matter is comprised of 9 to 30% by weight. casein and homogenizing the pigments and optionally fillers in a colloidal alkaline aqueous casein solution with additives. The resulting solution has a concentration of 30 to 60% by weight.