DE19910809A1 - Molded products with structured hydrophilic surface, e.g. for data storage media or reusable printing plates, contain polymers with thermally or hydrolytically cleavable perfluoro-alkyl groups - Google Patents

Abstract

Molded products with at least one surface showing structured hydrophilicity contain polymers (A) with side chains containing thermally or hydrolytically cleavable perfluorinated alkyl groups. Independent claims are also included for: (a) information storage media with polymers (A) as defined above on the surface; (b) reusable printing plates with polymers (A) on the surface; and (c) a process for the production of molded products as above, in which one or more surfaces of a molded blank is/are coated with polymer (A) and the coated surface(s) is/are partly hydrophilized by the directed local action of heat or hydrolytic agents.

Description

The present invention relates to moldings which have surfaces with structured Have hydrophilicity, as well as the use of polymers with thermal or side chains containing hydrolytically removable, perfluorinated alkyl residues their manufacture.

Macromolecules 29 (1996) 1229 are diblock copolymers of deuterated Styrene and isoprene are known which have heptafluorobutyroyl side groups. Ober Surfaces that have such block copolymers are extremely hydrophobic, they have contact angles greater than 100 ° for water.

It has now been found that the fluorinated side groups of these polymers differ at temperatures well below the decomposition temperature of the block copolymer let split off quantitatively. This makes the hydrophilicity of upper possible areas containing such block copolymers with fluorinated side groups, targeted to change. Surfaces with structured hydrophilicity can be created in this way. Furthermore, the hydrophilized areas of the surface can be changed again Settling again with perfluorocarboxylic acids or their derivatives.

In the same way, other polymers with perfluorinated alkyl radicals can be used pointing side groups are used to surface structured Hy to produce drophiles. It is only important that the side chains while maintaining the Allow the main chain of the polymer to be split off thermally or hydrolytically.

The invention relates to moldings which have surfaces with structured Hy have drophilia, which contain polymers which carry side groups, which have perfluorinated alkyl radicals. The moldings have at least one Surface on, but also several or even all surfaces of this Be kind.  

Surfaces with structured hydrophilicity are those that polymers with thermal or hydrolytically cleavable, perfluorinated alkyl residues containing side chains included, some of the side chains locally thermally or hydrolytically was split off. Due to the local splitting off of side chains on the Surface hydrophilic areas. The surfaces can thus be targeted Structures or patterns and so can also markings brings or information is stored on the surface.

Hydrophilizable block copolymers with side chains containing perfluorocarboxyl radicals are preferably used as polymers. These are particularly preferably block copolymers which contain at least one block A from polymerized units of monoethylenically unsaturated monomers and at least one block B from polymerized isoprene units which are bonded by hydrolysis of unsaturated double bonds and esterification with perfluorocarboxylic acids, for example trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutanoic acid or higher Homologs such as C ₇ F ₁₅ COOH, C ₉ F ₁₉ COOH C ₁₁ F ₂₃ COOH or C ₁₃ F ₂₇ COOH have side chains available.

At least 20 mol% are preferred, particularly preferably 30 to 80 mol% of the un saturated double bonds in block B in perfluorocarboxyl radicals Page groups converted. In a further particularly preferred embodiment The unsaturated double bonds are in the form of 100 mol% in perfluorocarboxyl radicals having side groups converted.

The molar ratio in the block copolymers is preferably that in block A. and block B containing monomer units at least 1: 2. Particularly preferred the molar ratio is at least 3: 1, very particularly preferably at least 4: 1.

The blocks A in the block copolymers are preferably derived from α-olefins, Vinyl aromatics, monoethylenically unsaturated mono- or dicarboxylic acids, the Esters, amides or anhydrides, particularly preferably of ethylene, propylene,  Butadiene, styrene, (meth) acrylic acid, its esters or amides, maleic anhydride or vinyl acetate, very particularly preferably styrene.

Blocks B are derived from isoprene units. They preferably have one statistical distribution of 1,2- and 3,4-linked isoprene units. Prefers each block B has at least 50, particularly preferably at least 100, completely particularly preferably has at least 150 isoprene units.

In a further preferred embodiment, the block copolymers correspond to the formula (I)

in which
m an integer ≧ 200,
n is an integer ≧ 100 and
R _{F is} a perfluorinated carboxyl radical.

An unsaturated double bond is formed on the block copolymers Pointed block copolymer containing isoprene units, the at least one Block A from polymerized units of monoethylenically unsaturated monomers and contains at least one block B of polymerized isoprene units, hydro xylated and the OH groups formed by the hydroxylation are by esterified a perfluorocarboxylic acid or its derivatives.

The starting point for the production of the block copolymers are block copolymers which Contain unsaturated double bonds containing isoprene units and min  least a block A of polymerized monoethylenically unsaturated units Monomers and at least one block B of polymerized isoprene units point. The preparation of such polymers is known to the person skilled in the art and at for example in Macromolecules 30 (1997) 2556 or Macromolecules 30 (1997) 1906 described.

The double bonds still contained in the isoprene units of these polymers are preferably at least 20 mol%, particularly preferably 30 to 80 mol%, in a further particularly preferred embodiment 100 mol% hydroxylated. The unsaturated double bond is preferably hydroxylated by hydroboration in an oxidizing medium. This is preferred aqueous alkali, particularly preferably NaOH in a concentration of 4 to 8 mol / l in combination with hydrogen peroxide, particularly preferably one 30 wt .-% hydrogen peroxide solution used. As a hydroboration agent 9-borabicylco [3.3.1] nonane is preferably used.

After the desired amount of double bonds in terminal hydroxyl Groups have been converted, these are under normal esterification conditions converted into side groups containing perfluorocarboxylic acid residues. Preferably the acid chlorides of perfluorocarboxylic acids are used for the esterification, which in can be produced in a known manner. The esterification is preferably carried out in an organic solvent, e.g. B. in tetrahydrofuran, preferably at Tem temperatures <50 ° C, particularly preferably 15 to 30 ° C.

The moldings according to the invention can be produced by one or several surfaces of a blank made of plastic, metal, glass, Wood or stone can exist in a manner known in principle to the person skilled in the art is coated with a perfluorinated side group polymer. Which he Shaped bodies according to the invention can also consist entirely of perfluorinated pages group-containing polymer produced by suitable shaping methods become. Then at least one surface, the perfluorinated sides  group-containing polymer contains, by targeted local exposure to heat or hydrolytically acting agents are partially hydrophilized and structured in this way.

The block copolymers described above are ideal for coating treatment of the surface of plastic articles. The coating can, for example are generated by the block copolymers on the optionally with a Primer pretreated surfaces of the items can be applied.

If the plastic to be coated is at least partially made of the same Monomers is constructed like block A of the block copolymers, is usually one sufficient adhesion of the coating even without pretreating the surface aims.

The coatings, the thickness of which is preferably in the range from 1 to 10 μm, can be applied by the methods familiar to the person skilled in the art for example by knife coating, coextrusion, spray coating or dipping.

Surprisingly, it is also possible to have perfluorinated side groups Polymers, especially the block copolymers described above, in the plastic incorporate mass from which the molded body is made, since the perfluorinated Migrate side group polymers to the surface of the molded part. The amount of polymer to be incorporated should be that for a coating of the ge Desired thickness correspond to the necessary amount.

The perfluorinated side group polymers (and containing tops surfaces) can be made hydrophilic by the action of heat, d. H. the fluorinated sides chains are split off by the action of heat. As a result, the will match part of the surface is hydrophilic. Provided that this heat effect is targeted and accurate localized, as can be done, for example, with the help of laser light the hydrophilization of the surface take place at previously precisely determined locations. This enables a lateral structuring of the hydrophilicity of the surface, which leads to  Information storage can be used, or to identify the Surface or the plastic or the molded part made from it.

An adsorption of hydrophilic substances or is also at the hydrophilized points a chemical reaction with substances reactive towards hydroxyl groups possible. For example, the hydrophilized ones can be reacted again Areas with perfluorinated carboxylic acids or their derivatives the surface hydrophobic again. This enables the production of molded parts, the upper have areas whose hydrophilicity can be reversibly changed.

For example, color can also be applied to the hydrophilized areas of the surface add fabrics. For example, by reacting with a fluorescence dye easily markings can be attached to the surface for example on plastics or molded parts made of plastic, to determine their origin or to label composition, for example for recycling these materials or objects can be used.

The perfluorinated side group polymers can also be made position of reusable printing plates. For this, printing plates are included equipped with the polymers, for example coated, and the surface of the Printing plate structured by targeted local heat, so that the Ink-receiving areas of the surface are hydrophilized. At the hy the printing dyes can then be attached to hydrophilic areas. According to the Be A series of prints can then be terminated, preferably after dye has been removed residues, the surface used for printing by renewed hydrophobization with perfluorinated carboxylic acids or their derivatives can be regenerated and he be described or structured again.

For hydrophilizing the polymers or surfaces that ent the polymers hold, the corresponding places up to a maximum of 20 Kelvin are preferred a maximum of 60 Kelvin, particularly preferably a maximum of 90 Kelvin below the Zer  Settling temperature of the polymer heated without fluorinated side chains. This Zer Settling temperature can be easily by common methods, such. B. Thermo gravimetry.

In a preferred embodiment, the block copoly described above mers or the areas of the surface to be hydrophilized to temperatures of Heated from 33 to 350 ° C. The duration of exposure to heat depends on the chosen one Temperature dependent. However, the average duration of treatment is 5 to 120 minutes, preferably 15 to 60 minutes is sufficient.

If a lateral structuring of the surface is intended, the Hy drophilization preferably use lasers or the surface by a ge Expose the desired structuring in the negative reproducing photographic mask.  

Examples example 1

By anionic polymerization of styrene and isoprene in a molar ratio of 1: 2 at -78 ° C in tetrahydrofuran, initiated by sec-butyllithium, a Blockco polymer made of polystyrene and polyisoprene.

10 g of the block copolymer are dissolved in tetrahydrofuran and in a temperature of -15 ° C treated with 67 ml 9-borabicyclo [3.3.1] nonane and with 7 ml 6 N NaOH and 14 ml of 30 wt .-% hydrogen peroxide worked up. The hy Droxylated block copolymer is isolated by methanol / water precipitation. The in Unsaturated double bonds contained in block copolymer are quantitatively hy doxylated.

5 g of the hydroxylated block copolymer are dissolved in tetrahydrofuran and at Treated 25 ° C with 0.1 to 0.2 g of heptafluorobutanoic acid chloride for 24 hours. There after the esterified block copolymer is isolated by precipitation with methanol / water.

Example 2

Analogously to Example 1, a block copolymer of polystyrene and polyisoprene in molar ratio 3: 1 produced and modified.

Example 3

Analogously to Example 1, a block copolymer of polystyrene and polyisoprene in molar ratio 4: 1 produced and modified.  

The block copolymers obtained in Examples 1 to 3 are replaced by twenty minutes Heat to the temperature indicated in Table 1 hydrophilized. The content of split off side groups and the specified temperatures are indicated by Thermogravimetry determined. The change in hydrophilicity is determined by the measurement the advancing contact angle of water drops is determined. Table 2 shows the increase the hydrophilicity after heating.

Table 1

Table 2

Claims (7)

1. Shaped body with at least one structured hydrophilicity Surface, which polymers with thermally or hydrolytically cleavable, Contains perfluorinated alkyl residues side chains. 2. Information store, the surface of which is polymer with thermal or hydro side chains which can be split off and contain perfluorinated alkyl radicals points. 3. Reusable printing plate, the surface of which is thermally polymerized or sides which can be split off hydrolytically and have perfluorinated alkyl radicals has chains. 4. The method for producing moldings according to claim 1, in which a or multiple surfaces of a blank with a perfluorinated side coated polymer and at least one coated Surface through targeted local exposure to heat or hydrolytically acting agents is partially hydrophilized. 5. Use of perfluorinated side group polymers Production of molded parts with at least one structured hydrophilicity having surface. 6. Use of perfluorinated side group-containing polymers Manufacture of molded parts that have surfaces, their hydrophilicity can be reversibly changed. 7. Use of perfluorinated side group polymers Labeling of plastics.