EP0850786B1 - Hotmelt transfer material, process for making the material, and the use thereof - Google Patents

Description

The invention relates to a hot melt transfer film according to the preamble of Claim 1, a method for producing the same, and its Use.

The design and manufacture of colored printed and painted T-shirts and Cloth bags attract attention. Fabric crayons and brush-workable stains available with heat-fixable dyes with which can be painted directly on textiles. Then the painted areas be heat set with a hot iron from the back so that the Color is washable. To apply the paint, the fabric must be stretched, otherwise wrinkles occur when painting, which makes processing difficult. moreover the limited range of colors limits creative freedom. On the other hand, there are hot melt transfer films (so-called Textile transfer films) available, which are printed using xerographic color copiers become. Any templates can be copied onto such foils and then transferred to textiles in ironing presses. In this way can also end up with paintings and drawings on paper Textiles are shown, but with a loss of quality in the Color rendering connected. For a direct designation and painting with the usual stains such as aqueous or solvent-based crayons, However, these foils are unsuitable for water colors and wax crayons. In US Pat. No. 5,242,739 describes hotmelt transfer films whose heat transferable layers are suitable for printing with thermal transfer and Matrix printers, but also suitable for painting with wax paints. This one Layers are not open-pore, watery colors are poorly accepted and insufficiently fixed. Hotmelt transfer foils have recently become available, which means Ink-jet color printers are printable, with the transfer on cotton containing textile fabrics can be done with an ordinary iron. Such films are described in US Pat. No. 5,501,902. To a Carrier material, which can be paper, is applied to a porous layer that thermoplastic, finely divided polymer particles, a binder based on a thermoplastic polymers and additives such as polyethylene glycols for quick Absorption and viscosity change of aqueous inks, included and others Additives for fixing the aqueous ink after transfer to textiles exhibit. The weight ratio of binder and polymer particles (pigment) is adjusted so that the layer has a porosity. This is the case if the ratio is close to the critical pigment volume concentration and the Layer has a tendency to chalk. This manifests itself in a minor mechanical strength of the layer. For direct labeling and painting with common stains used by children such as watery or Solvent-based crayons, water colors and wax crayons result in that hotmelt transfer films based on these patents are insufficient Results, because when labeling and painting watery colors such as Water colors to be applied with a brush are insufficient if the application is strong recorded or the layers when labeled with pencils or chalks mechanically injured because the particles of the porous layer are anchored too little are. In addition, by using additives in the layer like Polyethylene glycols fix the stains and thus wash fastness impaired, so that when washing the textiles in warm water the colors bleed out.

The object of the invention is therefore the known hot melt transfer films to be modified for the ink jet application in such a way that a direct painting with common crayons and paints used by children, which contain water-based paints, solvent-based paints, or wax paints, is possible and the colors are fixed in the washing process with warm water stay. The invention is based on the features of the invention characterizing part of claim 1 solved. Advantageous further training are the subject of the subclaims.

An improvement in the absorption and fixation of aqueous and solvent-containing colors is achieved in that the porous layer has porous, wettable particles made of thermoplastic material with the largest possible surface area for adsorption or absorption of the dye. Other additives described in the above-mentioned patent for the improved water absorption, which impair the washability, are omitted. The particles consist of porous, thermoplastic plastic particles with specific surfaces> 6 m ² / g and with a melting temperature <200 ° C. In this case, when the layer is hot ironed onto a fabric, the particles fuse together with the dye, binder and any other hot melt layers. Finding powders of thermoplastic materials that meet these conditions is proving difficult. Fine powders of plastics can be obtained by grinding and sieving. In this case, the average particle size is usually over 50 microns with a wide grain size distribution. The particles are spherical and the specific surfaces are below 0.2 m ² / g. Finer powders are obtained by precipitating the plastic from the solution directly during the manufacturing process. Depending on the conditions, powders with average particle sizes of approximately 5 to 90 micrometers are obtained, each with a relatively narrow particle size distribution, the particles generally also being formed spherically, so that the specific surfaces are below 2 m ² / g. Only with specially guided manufacturing, precipitation and gentle drying processes do porous particles arise, as primary particles themselves, or as stable aggregates with average particle sizes of 5 to 40 micrometers, which are formed from ultrafine primary particles, which can be smaller than 0.2 micrometers , Such particles have specific surfaces that are significantly above 2 m ² / g. Another advantageous property that such plastic particles should have is a wetting ability against water and solvents. A commercially available thermoplastic polymer powder consisting of such particles is, for example, a finely divided polyamide powder which is produced by means of polyaddition, a subsequent precipitation process and gentle drying, a surface area of approximately 25 m ² / g, a particle size of approximately 10 micrometers and a wettability against water and has solvents. Such particles adsorb or absorb significantly more dye than spherical particles with a smooth surface. A thermoplastic polymer that melts at a temperature of <200 ° C. is used as the binder, which anchors the particles sufficiently mechanically, but is minimally dosed and is selected such that the layer remains open-pored and the binder does not completely encase the porous particles. The thermoplastic binder advantageously has a melting temperature of <140 ° C., so that it can easily melt when transferred to textiles by the action of the hot iron or the ironing press. On the other hand, the binder should be resistant to washing solutions if possible. Examples of suitable binders based on aqueous dispersions or dissolved plastics can be found in the above-mentioned US Pat. No. 5,501,902. Binders based on dissolved plastics should be inert to the solvents used in the solvent-based paints.

A further improvement in the absorption of watery and solvent-based Colors and an improvement in mechanical stability is provided by a Binder layer, which itself has a porous or porous structure, reached. The inherent porosity or intrinsic porosity of the binder allows a much higher one Dosage of the binder in relation to the porous Particles far below the critical pigment volume concentration and thus far away from a tendency to chalk out. The porous structure of the binder itself promotes the access of aqueous and solvent-based paints to the Particles. A detailed overview of methods for producing porous Membrane layers with further literature references can be found in the book "Membranes and membrane processes" by Eberhard Staude, Verlag VCH, chap. 2.2.2.3 (wet precipitation) to Chap. 2.2.2.4 (combined dry-wet precipitation). Plastics are dissolved in a solvent and coated on a carrier (poured) and then immersed in a precipitation bath. The precipitant must be soluble in the solvent itself. There is a transition from sol to Gel state and thus coagulation. Then the porous membrane dried. Ternary mixtures (membrane polymer / Solvent / precipitant) porous layers are produced (see J.A. His & H.L. Gerhart, Xl. FATIPEC Kongress 1972, p. 131 (solvent precipitation)). A plastic is mixed in a single-phase solvent mixture Plastic solvent and a non-plastic solvent Contains precipitant (non-solvent), dissolved. The precipitant has one lower vapor pressure than the solvent. Solvents and precipitants should not have any miscibility gap with each other. The Membrane formation behavior can be described with triangular state diagrams become. If such a plastic solution is coated on a carrier and that Evaporated solvent, the precipitant accumulates in the Solvent mixture until a separation into two phases occurs at the gel point (Phase inversion), a polymer enriched phase and a phase with the Precipitant, which can consist of fine droplets that form the pores. On This way you can use a variety of plastics within an optimal Porous range of the mixing ratio of solvent and precipitant and / or porous layers can be produced. With deeper concentration of the Precipitant, only closed micropores are formed. Larger Concentration of the precipitant precipitates the polymer before the gel point is reached is. In this case, open-pore layers become powdery, loose Layers created. Mixed in the correct ratio, the gel state is reached, the pores containing the precipitant droplets. Drying results in porous, continuous polymer membranes with good mechanical stability. Under Under certain conditions, the pore walls during the drying process tear, resulting in porous layers. If this method becomes Formation of pores in the binder with the use of wettable, porous plastic particles combined, so are more achieved favorable effects. If the ternary mixture (polymer / solvent / Precipitant) dispersed into the system as a further component, contains porous particles, so form after coating Dispersion on a carrier when drying the pores preferably in the area of Particles from (nucleation). Droplets of the precipitant in the gel film can easily are absorbed and held by the porous particles their inner and outer surfaces largely free of binders. After this complete drying of the layer, the pores are preferably in the range of Particles, so that after the layer has dried, the absorption capacity of the particles preserved for water-based and solvent-based paints. In this way can even binder layers that are closed-pore by themselves in Presence of the particles porous layers of very good mechanical strength form. The proportion of binder in the layer can be up to over 50% by weight. The binder for the hot melt layer must have a melting temperature <200 ° C have, advantageously even <150 ° C. When choosing solvent / Precipitant must take care that these are the porous particles do not swell or dissolve. In addition, when selecting the binder, the Inertness to the solvents of the crayons (mostly alcohol) and the Attention to washing resistance. Suitable binders are for example polyesters, polyacrylates, polymethyl methacrylates, ethylene copolymers, Ethylene-acrylic acid copolymers and polyamides.

Synthetic papers or plastic foils, which are sufficiently heat-resistant when ironed on, can be used to support the porous hotmelt layer. However, papers are advantageously used as carriers. For better detachment of the carrier from the layer after ironing, siliconized carriers are advantageously used on one side. Such carriers are known as abhesive papers or papers siliconized on one side. Papers of 50-100 g / m ² are advantageously used. The siliconized side serves as an intermediate layer and must be sufficiently heat-resistant so that the painted layer does not bond with it and makes it difficult to detach after ironing and cooling. For improved fixation of the stains and improved adhesion to the textiles, the hot-melt transfer material according to the invention is advantageously equipped with a further auxiliary layer, which lies between the porous layer on the one hand and the carrier material or on one side siliconized carrier material and consists of a film-forming thermoplastic polymer. Suitable polymers for this purpose are thermoplastics with a melting range below 200 ° C., preferably polyester, hot melt adhesives for the textile industry, for example based on polyethylene, or sealable polymers, such as dispersions for heat-sealing layers, for example based on ethylene copolymers or in particular ethylene-acrylic acid copolyoxymethylenes. These polymers are also preferably selected so that their resistance to common solvents of the crayons is sufficient. In addition, the porous layer must adhere sufficiently to this layer so that it is not rubbed off when marking and painting.

A hot melt transfer film according to the invention is particularly suitable for Mark and paint with common crayons and paints such as watery or solvent-based crayons, wax crayons and water colors. aqueous and solvent-based paints are created by the porous particles in the porous layer quickly absorbed and well adsorbed respectively absorbed. When transferred to textiles, the porosity of the layer and disappears the thermoplastic, microporous particles with the dye are in the Binder and added in the second hot melt layer, respectively fused and thus permanently fixed. An equally good inclusion in the shift in the case of superficially applied wax paint when ironing on Textile reached. The labeling and painting on a hot melt transfer film according to the invention is as easy as on ordinary paper, so that can be painted with the familiar colors. A painted hot melt transfer film can easily be done from the back with a hot iron on white or colored cotton or cotton-containing textiles such as T-shirts or cloth bags can be ironed on. After pulling off the carrier that is painted motif in the original quality applied to the textile fabric and fixed in such a way that the textile fabric is used with warm water Common detergent washed without bleeding and color impairment can be.

The following example explains the invention.

example

1. Preparation of a Binder Solution for the Porous Hotmelt Layer: A saturated linear polyester, for example a Vylon type, is in one Mixture of methyl ethyl ketone and an alcohol dissolved, the alcohol has a higher boiling point than methyl ethyl ketone. For the later Dispersion of the porous particles and stabilization of the standing Dispersion can also be typical for organic fillers Dispersing agents are stirred. The concentration of the polyester in the solution should be about 10 to 30% by weight and that Mixing ratio methyl ethyl ketone / alcohol is adjusted so that when spreading the viscous binder solution onto a carrier and then dry at about 60 - 80 ° C porous layers form.

2. Porous particles: polyamide powder, for example Orgasol 3501 (grain size approximately 10 microns, specific surface area approximately 25 m ² / g).

3. Diluent: methyl ethyl ketone / alcohol in the same mixing ratio as above.

4. Aqueous dispersion for applying the hot melt layer (primer): A dispersion based on a sealable ethylene-acrylic acid copolymer, for example an Enorex type with a solids content of about 40%.

Action:

In a first step, the dispersion for the hot-melt layer (primer) is spread on the silicone side of a one-sided siliconized adhesive paper (80 g / m ² ) and then dried at a temperature of approximately 110 ° C. The dry application should be approximately 30 g / m ² . In a second step, the dispersion for the porous hot melt layer is prepared. Using a stirrer, portions of the polyamide powder (point 2) and the diluent (point 3) are alternately stirred into the binder solution (point 1) under dispersion conditions until a hand-knife-coated, all-purpose dispersion of suitable viscosity is obtained. The dispersion for the porous hot-melt layer is then spread onto the hot-melt layer (primer / 1st step) and dried at a temperature of approximately 60-80 ° C. The dry application should be about 30 g / m ² . The solids content of the binder, based on the porous hot melt layer, should be in the range from 30 to 50% by weight.

The layer has good mechanical stability and porosity and can be with the usual painting aids such as aqueous and solvent-containing crayons, Paint watercolors and crayons in the same way as ordinary paper. The Transfer to white and colorful cotton T-shirts is done with the iron about 190 to 200 ° C (heat setting for cotton). The hotmett transfer foil is with the put the painted side against the T-shirt and position it where you want it. With the iron, the back of the paper becomes thorough under strong pressure painted so that the color can melt with the layer and this with connects the fabric. When the paper back becomes hot again has cooled, the adhesive paper is removed. Then several can Washing processes carried out in a washing machine with common detergents become. The colors, even the water colors, turn out to be washable.

Claims (11)

1. Hot-melt transfer film with a porous hot-melt layer containing fine particles of thermoplastic plastics and a binder based on thermoplastic plastics, applied to a substrate, the particles anchored in the binder having a porous structure with a surface that is wetted by aqueous and solvent-containing paints and the paints are adsorbed or absorbed, the particles being in the form of powder with a specific surface of at least 6 m²/g and a grain size of between 2 micrometres and 50 micrometres, and the particles and the binder melt at below 200°C.
2. Hot-melt transfer film as claimed in claim 1, characterised in that the particles consist of polyamide.
3. Hot-melt transfer film as claimed in one of claims 1 or 2, characterised in that the binder itself has a porous structure and/or pores in the region of the particles.
4. Hot-melt transfer film as claimed in claim 3, characterised in that the pores of the binder are formed by wet precipitation, combined dry-wet precipitation or solvent precipitation.
5. Hot-melt transfer film as claimed in one of claims 1 to 4, characterised in that the binder contains polyester, polyacrylates, polymethyl methacrylates, ethylene copolymers, ethylene-acrylic acid copolymers or polyamides.
6. Hot-melt transfer film as claimed in one of claims 1 to 5, characterised in that a second hot-melt layer is applied between substrate and porous hot-melt layer.
7. Hot-melt transfer film as claimed in claim 6, characterised in that the second hot-melt layer contains polyester, polyethylene, ethylene copolymers or ethylene-acrylic acid copolymers.
8. Hot-melt transfer film as claimed in one of claims 1 to 7, characterised in that the substrate consists of a paper.
9. Hot-melt transfer film as claimed in claim 8, characterised in that a silicon layer is applied between substrate and hot-melt layer.
10. Method of producing a hot-melt transfer film as claimed in one of claims 1 to 9, characterised in that the dispersion for applying the porous hot-melt layer contains the particles, the dissolved binder, a precipitating agent and a solvent whose vapour pressure is higher than that of the precipitating agent and a substrate is coated with this dispersion and then dried inducing phase inversion and pore formation.
11. Use of the hot-melt transfer film as claimed in one of claims 1 to 9 for painting with aqueous paints, solvent-containing paints or wax-based paints and ironing onto fabrics.