DD281908A7 - METHOD AND DEVICE FOR PRODUCING HIGHLY ATMOSPHERABLE POLYACRYLATE ADHESIVE LAYERS - Google Patents

Abstract

The invention relates to a process characterized in that the polyacrylate pressure-sensitive adhesive is dissolved in a solvent or solvent mixture such that the solution has a viscosity in the range between 2,000 cP and 30,000 cP and a solids content between 25 and 60 * and this pressure-sensitive adhesive solution applied to the transfer substrate, a predrying at temperatures between 25 and 40C and a subsequent heat-shock treatment at temperatures between 80 and 120C is subjected. The invention further relates to an improved device for applying the adhesive, wherein an unstructured doctor blade in which the tilt angle 91a96 is at a phase angle of 20b60 and an angle g90 is used. Polyacrylathaftklebstoffschicht; Solvent; Viscosity; Solids content; pre-drying; Waermeschockbehandlung; Device; doctor; tilt angles; Phase angle}

Description

For this 3 pages drawings

Field of application of the invention

The invention relates to a method and a device for the production of self-adhesive highly breathable materials by coating of fabrics.

The field of application of the invention is thus in the medical field, in particular in the manufacture of medical patches.

Characteristic of the known state of the art

For some years now, it has been possible to produce breathable or highly breathable pressure-sensitive adhesive layers on a number of textile fabrics, preferably on nonwovens (DE-PS 1667940). It is known to use siiiko paper as a transfer carrier (DE-OS 2719779).

The highly breathable pressure-sensitive adhesive layers ensure an extremely high exchange of water vapor and air. In particular, polyacrylate copolymers, ie polymers having a different proportion of different monomers in a polymer molecule, are used in particular skin-friendly pressure-sensitive adhesives. From DE-OS 2719779 is also known that the adhesive is spread on the siliconized paper in the desired thickness of about 35 to 65 g dry matter per m ² .

Processes for the formation of bubble structures by means of a special temperature treatment after the AiMrag of the pressure-sensitive adhesive assume a dominant position. So z. B. ' in DE-PS 1569901 describes a worship in which by rapid drying over a blistering high permeability is achieved. Even in the processes which dry the drying in two stages (predrying and night drying AT 260426, US Pat. No. 3,426,754), this bubble formation plays the sole decisive role by evaporation of the solvent, with the solvent composition playing a special role (US Pat. PS 3 523846). The complete opening of the bubbles succeeds z. B. by special laminating conditions (DE-Utility Model 8015937).

The disadvantages of the o.g. Methods are in the difficulty of controlling bubble size, i. H. in the control of permeability (microporosity) by a broad distribution of pore diameter and in the problem of only partially opened bubbles, z. but still closed structures, which indeed increase the gas and vapor permeability, but still can not reach a sufficiently high value.

The problem of Stei.erunn the pore uniformity is solved only incomplete by the temperature control in the drying zone or by post-treatment. Alterations to the squeegee by grinding in structures bring about the risk of damage or tearing of the material to be coated. Air brushes or special roller application systems mean a high technological effort.

Object of the invention

The aim of the invention is the coating of fabrics with a skin-friendly pressure-sensitive adhesive for the production of highly breathable, self-adhesive, medical products.

Explanation of the essence of the invention

The invention has for its object to develop an improved process for the production of highly breathable pressure-sensitive adhesive layers and an improved device for applying the adhesive.

The process for the preparation of highly breathable Polyacrvlathaftklebstoffschichten with a stripförmon, interspersed with bubbles structure, wherein 35 to 60 g dry mass of the adhesive per m ² on a transfer carrier, which consists of siliconized paper, coated and laminated after the drying process as final carrier fabric, knitted or nonwoven fabrics, characterized in that the polyacrylate pressure-sensitive adhesive is dissolved in a solvent or solvent mixture such that the solution has a viscosity in the range between 200OcP and 3000OcP and a solids content between 25 and 60% by weight and this adhesive applied to the transfer support predrying at temperatures between 25 and 4O ⁰ C and a subsequent heat shock treatment at temperatures between 80 and 12O ⁰ C is subjected.

As pressure-sensitive adhesive solvents are used hydrocarbons, preferably hexane, heptane, benzines of different boiling ranges, esters, preferably methyl acetate, ethyl acetate, alcohols, preferably methanol, ethanol, propanol, ketones, preferably + acetone + methyl ethyl ketone or mixtures of the solvents mentioned on a state-of-the-art charging system, the basic structure of which is shown in Figure 1, the device being improved with respect to application of the adhesive according to the invention unstructured doctor blade (doctor blade or doctor blade) and doctor blade 2, from an adhesive box 3 a pressure sensitive adhesive based on a Polyacrylatlösungspolymerisates having a viscosity between 200OcP and 3000OcP and a solids content of 25Gew-% to60Gew .-%, preferably 40 wt. % to 50 wt .-% with a mass coverage of 35 gm " ² am 60gm" ² , preferably 40gm " ² to 50gm ~ ² , with respect to the solvent-free pressure sensitive adhesive to form regular stripe-shaped structures (dissipative structures), see Figure 3, first on a transfer support at coating speeds of 2mmin "'to 20mmin" ^{1 is} applied. According to Figure 2, when using a flat blade, the tilt angle 91 ° <α s 96 ° at a phase angle 20 ° · ΐ β <60 ° and at γ = 90 °. When using a round doctor blade, the tilt angle is also 90 ° s α <96 °. As transfer support are rendered abhesive paper or tissue, preferably a siliconized paper are smaller than 0.04 Ncm ^"1, having a basis weight of about 60gm ~ ^2, wherein the peel forces between the paper and pressure-sensitive adhesive layer is less than 0.1 Ncm ~ ', preferably, After a short predrying phase at room temperature in the predrying zone 12, a heat shock treatment at temperatures from 8O ⁰ C to 120 ° C, preferably at 100 ⁰ C to 12O ⁰ C in a nozzle dryer 5 is performed, the pressure-sensitive adhesive layer to form massive bubble-streaked strips to Finally, the preformed, porous pressure-sensitive adhesive layer is opened by means of a pair of laminating rollers 7/8 with opening of the bubble structures onto the film carrier, such as woven, knitted or nonwoven fabrics, in particular random webs, which can be chemically and / or mechanically consolidated by various methods. hiert.

The polyacrylate solution polymer used is a hypoallergenic polyacrylate pressure-sensitive adhesive suitable for medical purposes, which may consist of copolymers having different chemical compositions, for example different comonomer ratios, in accordance with the requirements, in particular with regard to adhesive strength, aging resistance, compatibility etc.

The invention will be explained in more detail with reference to the following pictures.

Figure 1 shows the basic structure of a coating system on which the inventive method is carried out; Figure 2 serves to illustrate the significant tilt angle α in the coating in conjunction with the

Phase angle β and the angle y

 Figure 3 shows the structured polyacrylate pressure-sensitive adhesive layer with structure maxima.

In the coating method according to the invention, the transfer carrier is transported from a transfer carrier unwinding 1 by means of a transport belt 6 via the doctor roller 2, the drying zone 12, the nozzle dryer 5 and a cooling roller 7 to the transfer line and from there to a transfer carrier take-up 9. The run of the final carrier is carried out by a final carrier processing 10 on the laminating roller 8 by rlie transfer distance to a final carrier rewind 11th

AufOhrungsbeispieie

The examples given here are intended to explain the process according to the invention:

example 1

A polyacrylate pressure-sensitive adhesive, which consists of a copolymer of 2 ethylhexyl acrylate and vinyl acetate, which is dissolved in a solvent mixture of ethyl acetate, ethanol, hexane and methanol in a ratio of 57: 32: 9: 2 and has a viscosity of 300OcP, is prepared by means of a rotary doctor blade a siliconized transfer carrier (paper with a surface mass of 70gm " ² and Abschälkräfton between Pa-ier and adhesive film of 0.04 Ncm" ¹ ) applied.

The round doctor blade (diameter 9.6 cm) is ji.stiert so that the tilt angle α = 93 °. The coating is followed by a container zone 12 with a Verwidilzeit of 30 seconds. The formation of dissipative structures

takes place directly on the doctor blade 4, wherein a temporary stabilization of the dissipative structures takes place in the Vertrockenzone at temperatures of 3O ⁰ C. At temperatures of 100 ⁰ C (1 minute) and 6O ⁰ C (2 minutes), the controlled strip-shaped foaming and drying of the pressure-sensitive adhesive film is achieved, which is a prerequisite for the achievable after the lamination on the Kaxhierwalze 8 good product properties. To the coated silicone paper, a Viskc cewirrvlies with a basis weight of 50gm ~ ² and a abhesively equipped back is laminated. The coated material produced in this way has the following parameters:

Mass circulation: GM45 ~ ² spacing of the maxima structure d: 2.4 mm water vapor permeability: 3100gm ~ ² d ~ ¹ Air permeability: 1.5 cm ^{3 Cm-2} S ^'1 (10mm WS)

The structures created by the dissipative structures on the doctor blade are documented schematically in Figure 3. Example 2 A polyacrylate pressure sensitive adhesive according to Example 1 is made by introducing about 5% of distilled water to a viscosity

adjusted from 15000 cP and registered by means of a flat blade 4 on a transfer carrier (analogous to Example 1). The flat blade (with a width of 7 mm is adjusted so that the tilt angle α = 92 ° and that for the voltage applied to the 1.5 mm wide compression zone angle β = 30 "was selected.

The coating is followed by drying as in Example 1. To the coated silicone paper is a subsequently calendered Viskosewirrvlies with a basis weight of about

50grrT ² and an abhesive backside laminated.

The material produced in this way has the following parameters:

Mass circulation: GM45 ~ ² spacing of the maxima structure d: 1.5 mm water vapor permeability: 2500gm ~ ² d ^"1 Air permeability: 1.4 cm ³ cm" ² s "'

Example 3 A polyacrylate pressure-sensitive adhesive, dissolved in low-boiling-point benzine, with a viscosity of 210OcP, is applied by means of a round doctor blade

a transfers ager applied as in Example 1.

Di'3 round doctor blade is adjusted so that the tilt angle α is 94 °. The coating is followed by drying as in Ex. 1. To the coated Trannferträger is a

Water-jet strengthened polyester non-woven fabric laminated and wound up.

After removal of the transfer carrier, the material produced in this way has the following parameters:

Mass circulation: 42g · m ^"2 spacing of the maxima structure: 2.8mm water vapor permeability: 3000 g · m ^-2 · d" ¹ Air permeability: 1,5crrT ² · s ^-1 · cm ³

Example 4 A Polyacrylathaftklebstoffbstoff, dissolved in ethyl acetate, with a viscosity of 2850OcP is with a doctor blade to a Transfer carrier applied. The doctor blade is adjusted so that the tilt angle is ο 92.6 °. The coating is followed by a pre-drying zone with a residence time of 30 seconds and a temperature of 30 ° C

and a main drying at 100 ⁰ C and a Verwoilzeit of 2 min and 6O ⁰ C at a residence time of 1 min on.

A chemically bonded viscose fiber random fleece with a basis weight of 40 g m ~ ^{2 is} laminated to the carrier carrier

and wound up.

The coated material produced in this way has the following parameters after removal of the transfer support:

Mass circulation: 49g · m ^"2 spacing of the maxima structure: 1.4mm • Water vapor permeability: 2100 g · m ^'2 · d" ¹ Air permeability: 1.2 cm ³ · cm ^"2 · s" ¹

Claims (4)

1. A process for the preparation of highly breathable Polyacrylathaftklebstoffschichten with a strip-like structure interspersed with bubbles, wherein 35 to 60 g dry mass of the adhesive per m ² on a transfer carrier, which consists of siliconized paper, brushed and laminated after the drying process as final carrier fabric, knitted or nonwoven fabrics characterized in that the polyacrylate pressure-sensitive adhesive is dissolved in a solvent or solvent mixture such that the solution has a viscosity in the range between 200OcP and 3000OcP and a solids content between 25 and 60% by weight and this adhesive applied to the transfer carrier is predrying at temperatures between 25 and 40 ⁰ C and a subsequent heat shock treatment at temperatures between 80 and 120 ⁰ C is subjected. 2. The method according to claim 1, characterized in that as pressure-sensitive adhesive hydrocarbon, preferably hexane, heptane, gasoline different boiling ranges, esters, preferably ethyl acetate, alcohols, preferably methanol, ethanol, propanol, ketones, preferably acetone, methyl ethyl ketone or mixtures of said solvents used become. 3. A device for carrying out the method according to claim 1, characterized in that for applying the adhesive ein9 non-structured doctor blade, wherein the tilt angle 90 ° <α <96 ° at a phase angle of 20 ° <ß <60 ° and an angle γ = 90 ° is used. 4. The device according to item 3, characterized in that are used as doctor blade squeegee or flat blade.