EP0029241B1 - Screen-like heat-sealing adhesive coating on plane substrates and process for its preparation - Google Patents

Description

The invention relates to a grid-shaped heat seal adhesive coating on textile fabrics or as a transferable layer on a transfer carrier material, consisting of a grid-shaped layer of two superimposed layers, obtained by the powder gravure printing process in one operation, and methods for producing such a grid-shaped heat seal adhesive coating.

The bonding of materials with a grid-shaped heat seal adhesive is known. This plays a special role in the bonding of textile materials and here in particular in the bonding of inserts with outer fabrics.

The production of heat seal adhesive coatings in grid form is carried out in various ways in the case of textile structures. Powder gravure printing processes, paste printing or screen printing process techniques, but also scattering processes can be listed as such processes. Depending on the type of process used, heat seal adhesives of different origins have been used. In the course of the increasing demands on the achievable adhesion, the avoidance of tension in the grip, the lack of creasing behavior of the fixing compound after the cleaning processes, etc., in the recent past there have been very high-quality adhesive materials, especially based on copolyamides, but also based on copolyesters and Mixtures of these are used. However, inserts loaded with grid-shaped coatings have also become known, which have been coated with PVC by the screen printing process. Inserts coated in this way showed, for example, a weak adhesion, a sweet smell, as well as a strong wrinkle and a paper-like hardening of the handle after cleaning the garment.

It has now surprisingly been found that grid-shaped heat seal adhesive coatings of the type mentioned at the outset are available using PVC-based plastic using the powder gravure printing process and do not have the disadvantages mentioned above of conventional coatings using the screen printing process using PVC. The invention thus relates to raster-shaped heat seal adhesive coatings on textile fabrics or as a transferable layer on a transfer carrier material, consisting of a raster-shaped layer of two layers lying one above the other, obtained by the powder gravure printing process in one operation, which are characterized in that one of the two layers made of PVC, optionally with a portion of plasticizer, or of plasticized PVC with an additional portion of other heat seal adhesive.

Commercially available fine-grained PVC powders are suitable as homopolymers or copolymers for producing suitable PVC-containing layers. As copolymers z. B. those made of vinyl chloride and vinyl esters are used. For example, a PVC polymer composed of approximately 85% vinyl chloride and 15% vinyl acetate can be used with very good success in the coating according to the invention.

In general, the PVC powder (which PVC copolymers are also to be included in this term below) is used in a grain size between about 50 to 150 μm. It is advantageous and necessary for many applications to add a proportion of plasticizer to the PVC powder. The proportion of the plasticizer can vary, depending on the type of PVC powder and the desired properties, in the range from 20 to 70% by weight, based on the PVC proportion. As a rule, however, the proportion of the plasticizer is particularly advantageously around 35 to 55% by weight, based on the PVC proportion.

Plasticizers for PVC are known. Powdered plasticizers, such as cyclohexyl phthalate, o-toluenesulfonic acid amide, p-toluenesulfonic acid amide, and mixtures thereof, have each been found to be particularly suitable for modification with plasticizers. Plasticizing components that can only be used in a limited amount, such as acid waxes in powder form, are also suitable.

The PVC-containing layer of the grid-shaped double coating can also have portions of (different from PVC) heat seal adhesive. These portions of heat seal adhesive can, which is particularly preferred, represent portions of the second layer, which acts as the primary adhesive layer. However, the proportions can also be so-called “foreign powder made of copolyamide and / or copolyester, which are not identical to that of the second adhesive layer. It is preferred to use a layer, which is also referred to below as a barrier layer, with a high proportion of plasticized PVC, which is expediently above 70% by weight. However, the proportion of plasticized PVC in the barrier layer can vary widely, for example it can be between 10 to 90% by weight, and particularly advantageously 60 to 90% by weight.

The second layer of the raster-shaped double coating, which is applied by the powder gravure process in the same operation, can be an adhesive layer made of copolyamide or copolyester or mixtures thereof. If necessary, small amounts of PVC can be added in individual cases, although this is not preferred.

A preferred grid-shaped double coating has an upper layer made of copolyamide and / or copolyester and a lower layer made of 90 to 10% by weight copolyamide and / or Copolyester and 10 to 90% by weight plasticized PVC.

The PVC-containing layer of the double coating according to the invention can either represent the underlayer on the substrate, which is preferred, but also alternatively the top layer depending on the type of bonding and the intended use of the substrate to be bonded. As an upper class it can e.g. B. on transfer carrier materials, such as transfer papers, from where it is then transferred together with the lower layer to other fabrics, such as outer fabrics of clothing, to make them adhesive.

The application of the heat seal adhesive coating according to the invention from two layers lying one above the other can be carried out in a manner known per se by the powder gravure printing process. Reference is made in particular to the method and the device for the grid-like application of double layers according to DE-3-25 36 911 of the applicant (corresponding to US-A-4139 613 and 4141 313). According to the process described there, the preferred plasticizer-containing PVC powders, especially when they are produced in a suitable form, can be knife-coated into the cavities of an engraving roller, for example, as a top layer, and can be peeled out again without leaving any residue. B. deposits are applied. In the case of a lower layer of conventional hotmelt adhesives, eg. B. from copolyamide or copolyester, which is the primary adhesive layer on the insert, the insert material provided with this coating shows typical fixing properties of a duo coating.

The grain fineness of the PVC-containing powders used, if they are knife-coated into the cavities as the upper layer, is in the coarser range up to about 250 wm, whereas the powders for the lower layer are finer and with a grain fineness of less than approx. 150 µm are preferred. Depending on the chosen grid arrangement, the selection of a special grain size may be favorable, whereby the grid arrangements with a distance larger than 15 mesh (e.g. 11 mesh) 150 j.lm sizes also give favorable results, while with a closer grid spacing (e.g. 17 mesh, 23 mesh) are advantageous grain finenesses below 100 j.lm are appropriate.

Before the powder is knife-coated, plasticizer is particularly advantageously introduced into the PVC-containing powder by means of a tempering process. Here, the PVC-containing powder mixture is generally annealed in a temperature range between 50 and 80 ° C., together with plasticizer powder, until the plasticizer has diffused almost or completely homogeneously into the PVC grains. In this way, an almost molecularly homogeneous distribution of the plasticizer component within the PVC grain, which is particularly favorable, is achieved. Tempering times of 1 to 5 days are usually sufficient for this, the tempering being carried out at rest or with slight movement. After the tempering process, the powder disintegrates again easily in a hammer mill into the grown primary grain, which, for example, starting from 150 µm in the starting grain, is in the grain range below approx. 200 to 250 µm.

If the PVC powder has additional proportions of heat seal adhesive, e.g. B. copolyamide and / or copolyester, the latter heat seal adhesive powder may be mixed in shortly before the application, but also, if appropriate, during the tempering of the plasticizer.

When carrying out the coating process, in order to increase the constancy of the composition of the two layers, it may be expedient to provide a stirrer, advantageously over the entire width, and a level control in the funnel into which the PVC-containing powders are poured. In this way, the powder level can be kept low in a favorable manner. Depending on the addition of plasticized PVC and the possibly present proportions of heat seal adhesive powder based on copolyamide or copolyester, almost constant mixture compositions of the barrier layer can be achieved in this way. For example, when adding pure plasticizer-containing PVC, an almost constant mixture composition of the barrier layer of e.g. B. 85 to 90 wt.% Plasticized PVC and 10 to 15 wt.% Powder substance, which comes from the second adhesive layer, can be achieved.

It may be appropriate to use a stirrer, e.g. B. a stir bar, and a level control to control the weight ratio of the layers to each other and the total amount of coating within narrow limits.

As already mentioned above, the PVC-containing barrier layer may also contain portions of heat seal adhesive. These portions of the heat seal adhesive can be the same as or different from that of the second adhesive layer. On the other hand, the second, actual adhesive layer normally advantageously contains no PVC powder.

The Hiessiegel coatings according to the invention give insert materials for the bonding with textile outer materials typical fixing properties of conventional duo coatings. Particularly noteworthy are the wide fixing tolerances without changing the grip under different fixing conditions, freedom from kickback and high adhesive strength, in particular also in the case of fixing bonds with outer materials that are difficult to fix, such as siliconized poplin.

example

50 parts by weight of a PVC suspension homo polymers with a particle size range of about 50 to 150 j.lm and a K value of 65 are mixed with the finely ground powders from 44 parts by weight of cyclohexyl phthalate, 10 parts by weight of a mixture of o- and p-toluenesulfonamide and 4 parts by weight. Parts of acid wax mixed and then annealed in a sealed plastic bag at 56 ° C for 72 hours. Approx. 8 days after cooling, the tempered material is broken into a primary grain using a hammer mill and then sieved through a 200 jim sieve. Any oversize is returned to the hammer mill and sieved again. The free-flowing powder is used for the hot seal adhesive coating of web-shaped interlining fabrics using the powder gravure printing process with two layers lying one on top of the other and is instilled into the cavities of a dot-engraved pressure roller (15 mesh) as the top layer. Copolyamide powder with a grain size of less than 150 µm is used for the lower layer of the engraving. The heating roller temperature is 190 ° C, the engraving roller temperature is 30 ° C and the coating speed is approx. 14 m / min. A rotating stirring rod is installed in both powder funnels and the level of the powder inside the funnel is regulated. The coating weight is about 20 g / m ² , of which 8 g / m ² consist of plasticized PVC and 12 g / m ² of copolyamide. The doctor blade thickness in the funnel with PVC filling is 0.3 mm. The squeegee edge is ground from 135 °. The PVC-containing top layer is used as the base layer and the copolyamide bottom layer as the primary adhesive layer. The insert cut out of the insert web is connected in the usual way to the outer fabrics by ironing. Good adhesion values of over 29.4 N / 15 cm are also achieved on heavily siliconized poplin. After cleaning the bracket assembly, neither the soft grip nor the adhesion has changed. No kickback is observed when ironing.

Claims (9)

1. Raster form heat-sealing adhesive coating on textile surface structures or as transferable layer on a transfer carrier material, consisting of a raster form layer of two superimposed layers obtained by the rotogravure powder method in one working process characterised in that one of the two layers consists of PVC, if necessary with a proportion of softener, or of softener-containing PVC with an additional proportion of another heat-sealing adhesive.

2. Raster form layer coating according to claim 1 characterised in that the lower layer provided on the textile inlay contains softener-containing PVC.

3. Raster form coating according to claim 1 or 2 characterised in that the softener content is 20 to 70 % by weight of the PVC proportion of the layer.

4. Raster form coating according to claim 3 characterised in that the softener content is 35 to 55 % by weight of the PVC proportion of the layer.

5. Raster form coating according to one of the preceding claims characterised in that the layer which contains softener-containing PVC has an additional proportion of heat-sealing adhesive.

6. Raster form coating according to claim 5 characterised in that the upper layer consists of copolyamides and/or copolyesters.

7. Raster form coating according to claim 6 characterised in that the upper layer consists of copolyamides and/or copolyesters and the lower layer consists of 90 to 10 % by weight of copolyamide and/or copolyester and 10 to 90 % by weight of softenercontaining PVC.

8. Method for the manufacture of the raster form coating according to the roto-gravure powder method according to claim 1 characterised in that a PVC-containing powder of particle size up to a maximum of about 250 µm is applied as one layer of a raster double layer.

9. Method according to claim 8 characterised in that a PVC-containing powder, into which the softener has been worked by tempering into a homogenous distribution, is applied if necessary in a homogenous mixture with additional copolyamide and/or copolyester heatsealing adhesive.