DE19829455A1 - A composition useful for hydrophilization of glass, metal and paper - Google Patents

Abstract

A strongly adhering surface layer of high surface tension is hydrophilized with an improved hydrophilization composition, comprising a water soluble binder containing OH and/or COOH groups, an epoxide functional metal oxide sol, pigment, and a pigment stabilizer. A surface coating hydrophilization composition comprises a water soluble binder containing OH and/or COOH groups, an epoxide functional metal oxide sol, pigment, and a pigment stabilizer of formula (I): The following definitions are not defined in the claims, but are disclosed as: M = NH4, Na, K or H; A = styrene or methylvinylether; n = 5 - 20; x = 0 - 40 mol.%; y = 10 - 50 mol.%; z = 50 - 65 mol.%. An Independent claim is included for the process for preparing the composition, in which an aqueous dispersion of the binder and metal oxide sol is added to an aqueous dispersion of the pigment and pigment stabilizer;

Description

The invention relates to a process for the hydrophilization of Surfaces, especially plastic, metal, paper or Glass surfaces to improve the writeability with what server-thinnable colors, for better wetting by what water or to repel hydrophobic colors.

The hydrophilization of surfaces is a known process to be able to implement special applications. Especially when labeling plastic foils or molded parts it is absolutely necessary to first hydrophilize to carry out wetting with aqueous coating solution secure solutions correctly. Furthermore, such a action also required to ensure adequate liability of the secure layer to be applied or label the film to design bar (EP 560 854). In lithography Offset processes such layers on aluminum or art Fabric films applied to the necessary color-repellent Get effect in the non-printing areas. It is also known to be hydrophilic layers on glass or metals apply in order to form droplets on contact with water vapor avoid or produce fat-repellent properties. It is also state of the art, mineral substrates sol Apply layers that deviate for organic colors are send and thus show an antigraphic effect (DE 42 40 108).

There are numerous processes for hydrophilizing surfaces known. A treatment with corona has been used for foils ("Coating", Vol. 4, 1997, p. 119) or with plasma ("Kunststoffe", Vol. 87, 1997, pp. 642-643). One disadvantage of this  However, the process is that the hydrophilization achieved is not is stable and decreases significantly with storage time. Flexible Offset printing plates based on polyester are predominant with heavily pigmented, hydrophilic lower layers to provide a strong color-repellent property after moistening to generate in the non-printing areas. It's be knows that there are layers of titanium dioxide, polyvinylal alcohol and aqueous tetramethoxysilane are suitable (EP 770 496). On The disadvantage of such layers is that they are very sensitive to water are and only after 6 days of heat treatment at 57 degrees are smudge-proof. Furthermore, it is often very problematic to obtain a pigment distribution in such layers or to realize stable and finely divided dispersions.

DE 37 16 440 proposes capacitor sheets made of aluminum with a mixture of polyvinylpyrrolidone and Treat silanols to prevent droplets from forming avoid sier water.

It is also known to use hydrophilic anti-fog coatings or apply grease-repellent layers to glass. So will proposed in DE 37 06 782, the glass surface with spe to treat particular silanes. In DE 38 17 953 layers described by the crosslinking of sulfo groups Obtained polyether diols and polysiloxanes with polyisocyanates become. By coating mixtures of silanes and Acrylic ester copolymers are also said to be hydro on glass phile properties can be obtained. For polycarbonate films it is proposed to coat with epoxy Silane hydrolyzates, polyhydric alcohols and polyacrylic acid esters to improve scratchability and To achieve anti-fog effect (DE 31 21 646).  

The object of the invention is to provide a verbes serify hydrophilizing composition that has been found to be good surface coating with a high surface span Suitable, and an improved method for hydrophi surfaces with new, pigmented layers, that adhere well to plastic or metal surfaces and one have high surface tension. The layers should follow Application and drying should be waterproof and good loading Show writability with water-thinnable colors.

This task is accomplished through a hydrophilizing composition or method with the features according to patent claims 1 or 7 or 10 solved. Advantageous embodiments and to Applications of the invention result from the dependent An sayings.

According to the invention, the object is achieved in particular in that a layer of:

• a) 30 to 50% by weight of water-soluble binder with hydroxyl and / or carboxyl groups,
• b) 8 to 30% by weight of epoxy-functional metal oxide sol,
• c) 30 to 50 wt .-% dispersed pigment and
• d) 1 to 10% pigment stabilizer of the general structural form
  

wherein
M = NH ₄

, Well, K, H
A = styrene, methyl vinyl ether
n = 5 to 20
R = C1 to C12 alkyl
x = 0 to 40 mol%
y = 10 to 50 mol%
z = 50 to 65 mol%
is applied.

The polymeric stabilizer preferably has a molecular weight weight of 5 to 20 kD and an acid number of 250 to 350 mg KOH / g.

The stabilizer can be produced in a manner known per se Way by polymer-analogous conversion of maleic anhydride Copolymers with alkoxypolyethylene glycols are made as described in "Acta Polymer", vol. 48, 1997, p. 16.

As water-soluble binders or polymers according to the invention are suitable polyvinyl alcohol, vinyl alcohol-vinyl acetate Copolymers, acrylic acid-acrylamide copolymers, acrylic acid Acrylic ester copolymers, cellulose derivatives such as hydroxyethylcel cellulose, carboxymethyl cellulose or natural polymers like gelatin. It is also possible as a water-soluble bandage medium Mixtures of hydroxyl groups and carboxyl groups to use pen-containing polymers. The molecular weight of the Binder is not critical and depends on the desired one viscosity and coating technology.

The epoxide-containing metal oxide sols are produced in a manner known per se by sol / gel technology, by hydrolyzing and condensing glycidalkoxysilanes in the presence of solvents and catalysts (see "J Non-Cryst. Solids", Vol. 121 , 1990, p. 370, or R. Reisfeld et al. In "Structure and Bonding" Vol. 77, Springer Verlag 1992). Examples of epoxy-containing silanes are:

Glycidoxypropyltrimethoxysilane
Glydidoxypropyltriethoxysilane
Glycidoxypropylmethyldiethoxysilane
3, 4-epoxycyclohexylethyltrimethoxysilane
3,4-epoxycyclohexylethyltriethoxysilane.

Mixing sols containing epoxy are preferably used, which are obtained by hydrolysis and condensation of silane mixtures or mixtures of epoxy silanes with alkoxy compounds of aluminum, titanium or zirconium. Examples of such mixtures are:

70% tetraethoxysilane
30% glycidoxypropyltrimethoxysilane

75% tetraethoxysilane
25% 3,4-epoxycyclohexylethyltrimethoxysilane

25% glycidoxypropyltriethoxysilane
65% tetraethoxysilane
10% titanium tetrabutylate

50% tetraethoxysilane
35% glycidoxypropyltrimethoxysilane
15% aluminum triisopropylate

70% tetraethoxysilane
20% glycidoxypropyltrimethoxysilane
10% zirconium tetrapropylate.

A is preferably used as the solvent for the sol production Use a mixture of alcohol and water or Acton and water det.  

The pigment can be dispersed in a manner known per se using high-speed agitators or ball mills respectively. The dispersion is preferably carried out in water Presence of the new stabilizer.

TiO ₂ , Al ₂ O ₃ or SiO ₂ are suitable as pigments. It is also possible to use mixtures of these. Pigments with a very small primary particle size are preferably used, so that they are present in dispersed form with an average particle size of 0.1 to 5 μm.

Examples of the pigment stabilizer according to the invention are polymers of the structural formula:

The concentration of the stabilizer is 1 to 20% preferably 5 to 10%, based on the pigment.

To avoid particle aggregation and very stable in storage Getting dispersions is preferred after finishing the water-soluble binder added to the dispersion.  

It is also possible according to the invention that the hydrophilic Layer also contains additional catalysts that the Reaction of the epoxy-containing metal oxide sol with the accelerate functional polymers. Examples of this are tert. Amines such as triethylamine or N-methylimidazole.

Furthermore, dyes can also be added to the layer be set.

Applying the coating solution to the coating the surfaces can be done with all known methods follow, such as spray painting, dip coating, Wash-on coating or extrusion coating. With non-polar It is advantageous for plastics such as polyethylene or polypropylene adheres to corona treatment before coating.

By the reaction of the metal oxide brine with the binders becomes a water-resistant hydrophilic after drying Received layer. The process continues to stand out from that very stable and finely divided pigment dispersion Nes are obtained which are distributed homogeneously in the layer. The layer has a high surface tension of at least 60 dynes / cm and is easily wettable and writable. she is also not sticky in high humidity and shows good adhesion processing on many substrates. This is suitable according to the invention Process for hydrophilizing glass, metal or art fabrics. It is still possible to change the layer accordingly DE 30 24 205 to apply as a functional layer on paper and such a good writability to rea with inkjet printers lize.

The layer according to the invention can u. a. find application for the glass and foil coating as well as sub layer for lithographic materials as well as for improvement the ink absorption of paper.  

Embodiments 1. Preparation of the pigment dispersions Dispersion A (comparative example)

100 g of TiO ₂ (P 25, Degussa AG) are in 900 ml of water containing 10 g of sulfonated naphthalene-formaldehyde condensate as a stabilizer for 30 min. dispersed using a high-speed agitator. After the dispersion has ended, 1 liter of 10% strength polyvinyl alcohol solution (molecular weight 92,000) is added with stirring. A stable dispersion with an average particle diameter of 1.2 to 1.4 μm is obtained.

Dispersion B

Analogously to the production process of dispersion A, 100 g of TiO ₂ are dispersed in water which contains 10 g of stabilizer based on maleic acid half-ester styrene (molecular weight 8000), acid number 280, EO chain length 8). The dispersion is stabilized with 1 liter of 10% PVA solution. A stable dispersion with an average particle diameter of 0.8 to 1.0 μm is obtained.

Dispersion C

Analogously to the production process for dispersion A, 90 g of Al ₂ O ₃ are dispersed in 900 ml of water, the 50 ml of 10% acetic acid and 10 g of stabilizer based on maleic acid half-styrene copolymer (molecular weight 12,000, acid number 300, EO chain length 12 ) contains. The dispersion is mixed with 1 liter of 10% PVA solution. It will contain a stable dispersion with an average particle diameter of 0.2 to 0.4 µm.

Dispersion D

Analogously to the production process for dispersion A, 100 g of SiO ₂ (Aerosil 200, Degussa AG) are dispersed in 900 ml of water, the 12 g of Na ₃ PO ₄ and 5 g of stabilizer based on maleic acid half-methyl vinyl ether copolymer (molecular weight 16,000, acid number 340 , EO chain length 12). The dispersion is stabilized with 1 liter of 8% gelatin solution. A stable dispersion with an average particle diameter of 1.2 to 1.5 μm is obtained.

Example 2 (comparative example)

In a manner known per se, a 1.8 μm thick layer (dry layer thickness) with the following pouring composition is applied to a 180 μm thick polyester film using a slot coater:

220 g dispersion A
33 g hydrolyzed emulsion of tetraethoxysilane (15%)

5 ml wetting agent (4%) based on sulfosuccinic acid salt.

After drying at 45 ° C., an opaque layer with a contact angle (H ₂ O, 25 ° C.) of 58 ° is obtained. In the case of mechanical stress when wet, the layer can be easily destroyed and removed from the base. An inhomogeneous pigment distribution can be seen in transmitted light.

Example 3

Analogously to Example 2, a layer with the following pouring solution composition is applied with a dry casting thickness of 1.5 µm:

200 g dispersion B
20 g PVA solution 10%
34 g of metal oxide sol 9.8% in ethanol / water 8/2
Tetraethoxysilane 66 parts
Glycidoxypropyltriethoxysilane 33Tl.
5 ml of 4% wetting agent.

It becomes an opaque layer with a homogeneous pigment distribution get that mechanically stable and damp even  is firmly anchored on the base. The contact angle is 57 °.

Example 4

Analogously to Example 2, a 2.2 µm thick layer with the following casting composition is applied:

185 g dispersion C
15 g PVA 10%
40 g of metal oxide sol 9.5% in ethanol / water 6/4
Tetraethoxysilane 66 parts
3,4-epoxycyclohexylethyltrimethoxysilane 33 parts
5 ml of 4% wetting agent.

An opaque layer is obtained, which is also in the damp Zu was mechanically stable and solid on the surface is anchored. The contact angle is 48 °.

Example 5

Analogously to Example 2, a 1.6 µm thick layer with the following casting composition is applied:

200 g dispersion D
48 g metal oxide sol 9.5% in ethanol / water = 6/4 from tetraethoxysilane 50 parts.
Methyltriethoxysilane 25 parts
Glycidoxypropyltrimethoxysilane 25 Tl.
5 ml setting agent 4%.

An opaque layer is obtained which is moist is stable and firmly anchored on the base. The edge angle is 59 °.

Example 6

Analogously to Example 2, a 40 μm thick polyethylene film is coated, which was treated with corona before the coating. A layer thickness of 1.2 µm is applied with the following casting composition:

200 g dispersion C
25 g PVA 10%
35 g of metal oxide sol 9.5% in ethanol / water = 8/2
Tetraethoxysilane 65 Tl.
Tetrabutylate 10 Tl.
Glycidoxypropyltriethoxysilane 25 Tl.
5 ml of 4% wetting agent.

An opaque layer is obtained, which is firmly on the film is anchored and can be easily written on with water-soluble inks is. The surface tension of the layer is 66 dynes / cm.

Example 7

Analogously to Example 2, a 30 μm thick polypropylene film is coated, which is treated with corona before the coating. A layer thickness of 1.9 µm is applied with the following casting composition:

210 g dispersion B
20 g PVA 10%
40 g of metal oxide sol 9.6% in ethanol / water = 7/3
Tetraethoxysilane 60 Tl.
Chloropropyltrimethoxysilane 15 parts
Glycidoxyproyltrimethoxysilan 25 Tl.
5 ml of 4% wetting agent.

An opaque layer is obtained, which is firmly on the film is anchored and can be easily written on with water-soluble inks is. The surface tension is 68 dynes / cm.

Example 8

An 8 µm thick layer with the following coating composition is applied to a base paper coated with polyethylene, which is treated with corona before coating:

200 g dispersion B
20 g polyvinylpyrrolidone 10% (molecular weight 120,000)
40 g of metal oxide sol 9.5% in ethanol / water = 6/4
Tetraethoxysilane 60 Tl.
Methyltrimethoxysilane 15 Tl.
Glycidoxyproyltrimethoxysilan 25 Tl.
8 ml 4% wetting agent.

After the layer has dried at 85 ° C, the paper is printed on using an HP Descjet 690C inkjet printer. A sharp print image is obtained with the following color densities:

Purple: 1.9
Blue: 1.8
Yellow: 0.9.

The colors are firmly anchored in the layer.

Example 9

Analogously to Example 8, a 12 µm thick layer is applied with the following coating solution:

180 g dispersion D
50 g polyvinylpyrrolidone 10%
35 g of metal oxide sol 9.5% in ethanol / water = 7/3
Tetraethoxysilane 60 Tl.
Chloropropyltrimethoxysilane 10 Tl.
Glycidoxypropyltriethoxysilane 30 Tl.
10 ml of 4% wetting agent.

After drying and printing, a sharp print image with the following color densities is obtained:

Purple: 1.9
Blue: 1.7
Yellow: 0.8

Claims (13)

1. Hydrophilization composition for coating surfaces, the water-soluble binder with hydroxyl and / or carboxyl groups, epoxy-functional metal oxide sol, dispersed pigment and a pigment stabilizer of the general structural formula
contains. 2. A hydrophilizing composition according to claim 1, wherein 30 to 50% by weight of the binder, 8 to 30% by weight of the Metal oxide sol, 30 to 50% by weight of the dispersed pigment and 1 to 10% by weight of the pigment stabilizer is provided. 3. Hydrophilization composition according to claim 1 or 2, which contains a catalyst agent which is used to accelerate the Reaction of the metal oxide sol with the functional polymers in the composition is provided. 4. Hydrophilization composition according to one of the preceding claims that contains dyes. 5. Hydrophilization composition according to one of the preceding claims where the pigment is alumina, silicon dioxide, titanium dioxide or a mixture of these.   6. Hydrophilization composition according to one of the preceding existing claims, in which the water-soluble binder Polyvinyl alcohol or a vinyl alcohol-vinyl acetate copolymer or gelatin or a gelatin derivative. 7. Process for making a hydrophilization together Setting according to one of claims 1 to 4, in which a dis persion from the pigment and the pigment stabilizer in water produced and the dispersion of the binder and the metal Oxide sol can be added. 8. The method according to claim 7, wherein the dispersion with Agitators or ball mills are carried out. 9. The method according to claim 7 or 8, in which pigments with are added to such a small primary particle size, that in the dispersion an average particle size in Range from 0.1 to 5 microns is given. 10. A method for hydrophilizing surfaces, in which a surface to be treated with a hydrophilization agent composition coated according to any one of claims 1 to 6 becomes. 11. The method according to claim 10, wherein the coating is a Spray painting, dip coating, spray coating or Extrusion coating includes. 12. The method according to claim 10 or 11, in which prior to loading layering a corona treatment takes place.   13. Use of a hydrophilizing composition according to one of claims 1 to 6 for the hydrophilization of glass, Me metal or material surfaces or for the production of radio layers on paper to improve writeability paper with ink.