DE964628C - Process for the production of self-adhesive sheets or tapes - Google Patents

Description

Process for the production of self-adhesive sheets or tapes The invention relates to. on a process for the production of self-adhesive Sheets or ribbons that have a flexible, sheet-like backing made of hydrophilic organic material with a smooth surface, one on the base Intermediate layer and a pressure-sensitive adhesive layer applied thereon own.

Under "hydrophilic organic material" is in the present context such a material is understood to be essentially hard when dry and is brittle, but flexible or pliable due to water absorption in the air will. These include, in particular, cellulose hydrate, gelatin, etc., as well as those polyamides, which have a water absorption capacity of a few percent in moist air (cf. P u m e r e r, Chemical Textile Fibers, Films and Foils, 1953, pp. 1399 ff.).

It is known to provide self-adhesive tapes with an intermediate layer, to improve the adhesion of the adhesive layer to the base. Special Difficulties are encountered, however, if hydrophilic foils are used as a base, z. B. those made of cellulose hydrate or moisture-absorbing polyamides, used ' to which the hydrophobic adhesive layers are to be applied. For improvement the adhesion of such hydrophobic adhesive layers to hydrophilic films are z. -B. Intermediate layers of rubber and resin or rubber latex and polyvinyl alcohol has been proposed. It is also known for anchoring self-adhesive layers based on nitrocellulose, a plasticizer for nitrocellulose such as dibutyl phthalate, and one or more soft, tackifying synthetic resins, such as with castor oil modified alkyl resin, resin glyceryl ester or soluble phenol formaldehyde resin, on hydrophilic substrates, e.g. B. from regenerated cellulose, primer layers from a suitable dilute adhesive or emulsion such as casein methyl acrylate or a vinyl acetate or methyl methacrylate emulsion. According to others In this process, cellulose hydrate films are first treated with isocyanate solutions or isocyanates are added to the solutions used to produce the hydrophobic layers. It can also. a treatment of the cellulose hydrate films with polyethyleneimine or Polyalkylenimines take place. Finally, interlayers made of polymerizable materials are also available Compounds containing an olefinic double bond and ethylene, B-dicarboxylic acids or their derivatives, especially the anhydrides, proposed for the same purpose.

In the "Pocket Book of Putties and Adhesives" by Micksch-Plath, 195a, Pp.88 and 89, it is described that all "Lutonale" in contrast to the "Oppanolen" strong adhesion (adhesive strength), but low cohesion (mechanical strength) have, so that they are mainly used where the adhesive layer is not hard may and should remain permanently elastic, as with insulating tape, adhesive plaster etc. Since the "lutonals" have a very low viscosity in solution, they should in the processing of adhesives for technical and economic reasons Reasons with viscosity-increasing substances, e.g. B. with »Oppanol C«, as a thickening or extenders are added. On p. 9o of the aforementioned pocket book, with With reference to "LutonalI6o" stated that when mixed with "Oppanol C" it is very elastic Adhesives for the shoe and rubber industry and for body construction are created. In addition, "LutonalI6o" is suitable for adhesive plasters, technical fastening tapes, and insulating tapes etc.

From the suitability of the »Lutonale« or mixtures of »Lutonale« with »Oppanol C« for adhesives no conclusions can be drawn about the use of these Fabrics drawn for the production of intermediate layers in self-adhesive tapes will. Mixtures of "Lutonal" and "Oppanol C" do not improve the anchorage of self-adhesive masses on substrates made of hydrophilic organic material.

If you were to use a dilute solution of an adhesive from »Lutonal I 6o "and" Oppanol C ", as it is known and customary for pressure-sensitive adhesives is applied as an intermediate layer on a hydrophilic film, then anchored this mixture by no means firmly on the foil and does not give a usable primer, although the mix is a good glue, in the field of the manufacture of the intermediate layers for pressure-sensitive adhesive strips are the Conditions are completely confusing, and it can by no means be predicted which substances improve the anchoring of the self-adhesive masses on the substrate, in particular one made of hydrophilic organic material. In particular such a prediction is not possible due to the described suitability of »Lutonal« or mixtures of »Lutonal« with viscosity-increasing substances such as ».opanol C «, as an adhesive.

According to the invention, a very special primer is applied to the applied hydrophilic film, which consists of a mixture of water-soluble polyvinyl ether with an emulsion of insoluble polyvinyl ether. This special one Primer differs fundamentally in its effect from »Lutonal« as a dispersion adhesive or »Oppanol« as a solvent adhesive in organic solvents or mixtures of the foregoing, as there is an unexpected improvement the anchoring of self-adhesives on hydrophilic foils.

It has now been found that the adhesiveness can be achieved in a very simple manner of hydrophobic, pressure-sensitive adhesive layers on hydrophilic substrates can by adding intermediate layers of mixtures of aqueous emulsions of polyvinyl ethers hydrophobic nature with aqueous solutions of polyvinyl ethers of a hydrophilic nature applies the documents and then after the drying of the intermediate layer Self-adhesive of the known type provides. In this way you get an extraordinary good adhesion of the adhesive to the hydrophilic substrates. The hydrophilic polyvinyl ether can in the mixture, partly through water-soluble colloids, such as glue, gelatin or casein.

The ratio of hydrophobic to hydrophilic polyvinyl ether can vary in the mixture within wide ranges and depends, among other things, on the thickness and material of the base and the type of adhesive spread away. Useful results will be obtained using ratios from z to 20 parts by weight hydrophilic polyvinyl ether to 99 to 80 parts by weight of hydrophobic polyvinyl ether obtain. A ratio of 10 parts by weight of hydrophilic is particularly suitable to 90 parts by weight of hydrophobic polyvinyl ether with a foil thickness of 0.5 mm Cellulose hydrate and an adhesive based on rubber resin or polyvinyl isobutyl ether.

The mixtures can also contain fillers and, if appropriate, dyes as well as wetting and thickening agents can be added. It has proven to be useful adjust the thickness of the intermediate layer so that after dry About 1 to 3 g of dry intermediate layer remain per square meter of film.

The use of interlayers made from mixtures of aqueous emulsions of polyvinyl ethers of a hydrophobic nature with aqueous solutions of polyvinyl ethers hydrophilic nature on hydrophilic substrates leads to a particularly good anchoring customary hydrophobic self-adhesive compositions, both those based on polyvinyl ether as well as those based on rubber resin or the like. An essential advantage of the invention available intermediate layer compared to known rubber-containing intermediate layers consists in their high resistance to aging.

The invention is explained in more detail below using a few exemplary embodiments. Example i A cellulose hydrate film was provided on one side with a thin intermediate layer made of a mixture of the following composition: After drying, the film provided with the intermediate layer was provided on the side primed in this way with a customary, known self-adhesive composed of a mixture of polyvinyl isobutyl ethers of different degrees of polymerization dissolved in a solvent such as gasoline. After the solvent used had evaporated, the adhesive film was cut into narrow strips, which were then wound up into rolls. The adhesive had excellent adhesion to the film and did not separate when the adhesive strip was peeled off the roll. After the removal of the adhesive strip, no residues of adhesive were left on surfaces to which the adhesive strip was temporarily stuck.

Example 2 A polyamide film (moisture content about q.0 / 0 at 65% relative humidity / '2-o') was primed with an intermediate layer of the following composition: Weight share solid Dispersion of polyvinyl iso- butyl ether (K = 55, dry solids content 55 '/ 0) - (Lu- tonal I 6o D, registered Trademarks) ........... 3.925 54.0 Solution of polyvinyl methyl ether (K = 4o) - Lutonal M 40, registered goods characters) in water (500 / 04g) 0.48 6, o Finely dispersed silica .... 1.2 30.0 Thickener (Collacral P, 3.20 / 04g, registered goods characters) ............ "" - - 7.5 6, o Wetting agent (33.3%) ....... 0.48 4.0 Water ... .. .. .. .. .. .. .. .. 86.415 - 100,000 f00.0 After the intermediate layer had dried, the film was provided with a self-adhesive spread in the same way as in Example 1.

Here, too, the adhesive was anchored very well on the film.

Example 3 On one with the same intermediate layer as in Example 12 provided cellulose hydrate film, a normal rubber adhesive became better known Type (natural rubber resin, dissolved in gasoline) applied. The adhesive stuck firmly on the slide.

Example 4 For the anchoring of self-adhesive compositions based on polyisobutylene, an intermediate layer made of a mixture of the following composition has proven to be advantageous: Weight share solid Dispersion of polyvinyl iso- butyl ether (K = 55, dry solids content 55 0/0) - (Lu- tonal I 6o D, registered Trademarks) ... .. ...... 3.28 36, o Solution of polyvinyl methyl ether (K = 40) - Lutonal M 40, registered goods characters) in water (50%) 0.4 4.0 Dispersion of polyisobutylene (500 / 04g) (dispersion of Oppanol B, registered Trademarks) ............ 3.0 30.0 Finely dispersed silica. ... 1.0 20.0 Wetting agent (33.3%, ig) ....... 1.05 7.0 Thickener (Collacral P, 3.7% 04g, registered goods characters) ................ 4.05 3.0 Water ................... 87.22 - 100.00 100.0 A cellulose hydrate film was provided with an intermediate layer of the above mixture and, after drying, coated with an adhesive layer based on polyisobutylene. The adhesive was anchored very firmly on the film.

Claims (6)

PATENT CLAIMS: i. Process for the production of self-adhesive Sheets or ribbons, in which a flexible, film-like base made of hydrophilic organic material provided with an intermediate layer and on this intermediate layer a pressure-sensitive hydrophobic adhesive layer is applied, characterized in that that for the intermediate layer a mixture of an emulsion or a dispersion hydrophobic polyvinyl ether with an aqueous solution of a hydrophilic polyvinyl ether is used. 2. The method according to claim i, characterized in that as hydrophilic Underlay made of cellulose hydrate or a moisture-absorbing polyamide is used. 3. The method according to claim i or 2, characterized in that for the intermediate layer a mixture of a dispersion of polyvinyl isobutyl ether and a solution of polyvinyl methyl ether is used. 4. Procedure after a of claims i to 3, characterized in that one for the intermediate layer Mixture is used, which also contains fillers and optionally dyes as well as wetting and thickening agents. 5. The method according to any one of the claims i to 4, characterized in that the solution of the hydrophilic polyvinyl ether partly by an aqueous solution of a colloidal substance such as glue or gelatin or casein. 6. The method according to any one of claims i to 4 using an adhesive based on polyisobutylene, characterized in that a mixture is used which also contains a dispersion of polyisobutylene contains. Considered publications: German Patent Specifications No. 862 818, 855 2g6, 763 107; M i c k s ch and P 1 a t h, »Pocket Book of Putties and Adhesives«, 1952, pp. 88 to 9o; "Kunststoffe" magazine, 1942, pp. 51 to 53.