GB2126163A

GB2126163A - Transfer printing method

Info

Publication number: GB2126163A
Application number: GB08322018A
Authority: GB
Inventors: Motoyasu Nakanishi
Original assignee: Cubic Eng Kk; Cubic Engineering KK
Current assignee: Cubic Eng Kk; Cubic Engineering KK
Priority date: 1982-08-17
Filing date: 1983-08-16
Publication date: 1984-03-21
Also published as: DE3328345C2; DE3328345A1; GB2126163B; FR2531909A1; GB8322018D0; IT1159494B; IT8367872A0; FR2531909B1; JPS5931185A; JPH0225360B2

Abstract

A method of applying a pattern to an object made of an organic polymeric material by transfer printing, which comprises: a) providing a water-swellable film having a transfer pattern printed thereon with a non-aqueous ink which comprises a solution or dispersion of a water-insoluble dye and a resin which fixes the pattern in an organic solvent. b) placing the film on the surface of the water in a water bath, with the transfer pattern face up, c) bringing the object into contact with the film by partially or completely immersing the object in the bath, the surface of the object at least in the area contacted by the pattern being penetrable by the ink, d) allowing the ink to penetrate into the surface of the object to form the pattern therein and e) removing the film from the object. The ink pattern may be applied to the film immediately prior to transfer, or it may be dried onto the film, when it is necessary to activate the dried film by use of the organic solvent, which may also include the resin.

Description

SPECIFICATION Transfer printing method This invention concerns a method of printing a pattern onto an organic polymeric object by a transfer method in which the pattern is transferred from a carrier film to the object in a water bath.

Transfer techniques of this kind have been suggested in the past but have been generally unsatisfactory in that the pattern merely adheres to the surface of the object and is therefore easily worn away.

We have now found a method in which the pattern penetrates into the surface of the object and thus gives a more hard-wearing product.

The invention thus provides a method of applying a pattern to an object made of an 'organic polymeric material by transfer printing, which comprises: a) providing a water-swellable film having a transfer pattern printed thereon with a nonaqueous ink which comprises a solution or dispersion of a water-insoluble dye and a resin which fixes the pattern in an organic solvent, b) placing the film on the surface of the water in a water bath, with the transfer pattern face up, c) bringing the object into contact with the film by partially or completely immersing the object in the bath, the surface of the object at least in the area contacted by the pattern being penetrable by the ink, d) allowing the ink to penetrate into the surface of the object to form the pattern therein, and e) removing the film from the object.

The method of the invention may be used to apply patterns to objects of many kinds, for example vessels or other containers, and decorative or useful objects such as toys, door knobs and spectacle frames. The word "pattern" as used herein includes both decorative, pictorial and abstract designs and lettering.

The object to be printed may if desired be pretreated and/or post-treated to facilitate penetration of the ink into the surface, and the object may also be subjected to additional dyeing and finishing steps. The film used to carry the pattern may be printed for immediate use, or it may be first printed and dried and then re-activated after storing.

The object to be printed by the method of the invention may be formed of any suitable natural or synthetic organic polymeric material which is penetrable by the ink solvent or can be made penetrable, at least in the area to which the pattern is to be applied. Thus the ink solvent penetrates into the surface the material and swells the polymer by parting the polymer chains.

The other constituents of the ink (particularly the dye and resin) are carried into the surface of the material with the solvent, and thus the pattern penetrates into the surface of the object.

The polymeric material may be rigid or flexible and cellular or non-cellular, examples of suitable material being cellulose and derivatives thereof such as cellulose acetate and cellulose propionate, epoxy resins, nylon and other polyamides, polyolefins and substituted polyolefins such as polypropylene and polyvinylchioride, and acrylic polymers and copolymers such as polymethylmethacrylate and acrylonitrile-butadienestyrene polymers.

The film which is used to carry the transfer pattern is made of a water-swellable material, that is, a material that expands on contact with water. The film may also be water soluble and it may be made of natural or synthetic material such as polyvinylalcohol polyacrylate salts and amides, and polyethers such as polyethyleneoxide, polyvinylpyrrolidone, methylcellulose, carboxymethylcellulose, starch, gelatin, casein, dextrin, albumin, soyabean protein, gum arabic, tragacanth gum or an alginate. A polyvinylalcohol film is preferably used. The film should be relatively thin and it is generally 30-40 microns thick.

Depending on the characteristics of the particular film used, the film may become removed in the bath during the transfer step. It is however, not usually possible to remove all of the film in this way and it is therefore desirable to wash the film off (e.g. with water) after removing the object from the water bath.

As regards the ink composition used, this contains a dye as compared to the pigments which have been used in the past and the penetration of the ink into the surface of the object is enhanced by.the affinity of the dye to the polymeric material. The dye may be present in the ink composition in an amount of 130% by weight. The dye may for example be an oil-soluble dye (for example an azo dye, an anthraquinone dye or a fatty acid salt dye), a disperse dye (such as used for dyeing synthetic resins) or a metallic complex salt dye such as used for dyeing nylon and wool. Examples of suitable dyes are Amacron (American Anilin Products Inc.), Diamix (Mitsubishi Chemical Industries Ltd) and Kayalon Polyester (Nippon Kayaku Co. Ltd).

The solvent used in the inks may be a waterimmiscible solvent, e.g. a hydrocarbon such as toluene, or a water-miscible solvent. e.g. esters such as ethyl acetate and lower alkanols such as isopropyl alcohol or butyl carbinol. When the film is printed for immediate wet use, a waterimmiscible solvent is preferably chosen. The solvent is generally present in the ink composition in an amount of 6070% by weight.

The resin present in the ink acts as to fix the pattern both to the film and to the object to be printed. The resin may for example be a synthetic resin such as an alkyd resin (particularly a relatively short chain alkyd resin) or a semisynthetic resin much as nitrocellulose or hydroxypropylcellulose. The resin is generally present in the ink in an amount of 1020% by weight.

The pattern-fixing resin is preferably water insoluble but a water-soluble material such as hydroxypropylcellulose may be used, as the contact time is short.

The film printed with a pattern using the above ink composition may be used directly in the method of the invention. Alternatively and preferably, the film may be printed, dried and stored and reactivated for use when needed. In this latter method, any suitable ink containing the chosen dye may be used to print the pattern initially, and for example the film may be gravure printed. The dry pattern is then re-activated for use with an activating composition which dissolves or disperses the dye to form an ink composition as described above. Thus, the activating composition will usually contain the organic solvent and the pattern-fixing resin.

The composition may also include for example up to 10% by weight of additives such as a plasticiser (e.g. dibutyl phthalate) and/or an extender (e.g. precipitated barium sulphate and/or barium carbonate). The plasticiser helps to prevent the ink becoming thixotropic, and the extender helps the ink to become fixed and the solvent to evaporate after removal of the film.

The transfer of the pattern from the film to the object while in the water bath takes place under the influence of the pressure of the water in the bath. The film should of course be kept in contact with the object for a sufficiently long period of time for the transfer to be completed, typically 5-10 seconds. Shorter or longer contact times may be used if desired.

Suitable apparatus for performing steps (b) and (c) is described in British Patent Specification 1515325.

Before use in the method of the invention, the object to be printed may be pre-treated to facilitate penetration of the ink into the surface a.nd this may be effected in various ways. The object may for example be wet-expanded with hot boiling water, for example by immersion, or it may be treated with a solvent for the polymeric material at an elevated temperature. Alternatively, the pre-treatment may be effected with the same kind of aqueous emulsion as is used in the posttreatment step described below.

The printed objects may also be post-treated after removal of the film to promote penetration of the ink into the surface of the object. In some circumstances, e.g. when the solvent is watermiscible, such treatment may be effected with water. Generally however penetration promotion is effected with an aqueous emulsion of a solvent or a chemical which degrades the polymeric material slightly. Depending on the particular polymeric material of the object to be printed, the solvent may for example be phenol or a substituted phenol (e.g. o-phenylphenol), an aromatic acid (e.g. benzoic acid), a chlorinated aliphatic or aromatic hydrocarbon (e.g. CCl4 and monochlorobenzene) or a hydrocarbon (e.g. methylnaphthalene).A surface active agent may be included in the composition, examples of suitable materials (particularly for use with CCl4) being Sunsalt 7000 and Carrier CH37 (Nikka Kagaku Kogyo Co. Ltd; Carrier CH37 is a chlorinated aromatic anionic surfactant).

Post-treatment using the above emulsions is usually carried out at 50--800C, for example by immersing the printed object in a bath of the emulsion.

The object may be pre-treated and/or posttreated as described above, but preferably posttreatment only is used.

The object may also be subjected to and additional dyeing step before or after application of the transfer pattern, to provide either a base (background) colour or a superimposed colour, which varies the colour or design of the transfer pattern. The desired dyes can be included in the pre-or post-treatment baths, but they are preferably applied in a separate step. Disperse dyes of the kind normally used to dye synthetic resins are generally preferred for this purpose and these are usually applied in the form of an aqueous emulsion containing a surfactant.

Finally, the object may be subject to a finishing process to remove any residual dye or treatment liquid and if desired to polish or top-coat the final product. Top-coating is unnecessary in many circumstances as the pattern is fixed within the surface of the object, but a top-coat may bt; applied where exceptional durability or a special finish is required.

The following examples illustrate the invention.

Percentages and parts are by weight. The alkyd resin used was a phthalic acid/glycerol alkyd resin renatured with soyabean oil.

Example 1 The following are examples of inks which may be used in the method of the invention.

Ink 1 Oil-soluble dye* 16.1% Nitrocellulose (7 parts) 17.2% Alkyd resin (3 parts) Ethyl acetate 1 9.4% Toluene 31.2% I.P.A. (isopropylalcohol) 16.1% total 100% Ink2 Oil-soluble dye* 1 6.1% Nitrocellulose (7 parts) 16.5% Alkyd resin (3 parts) Ethyl acetate 24.5% Cyclohexanone 30.8% I.P.A. 12.1% total 1009/0 Ink3 Disperse dye 13.3%** Resin: Nitrocellulose 7 parts 10 7% Alkyd resin 3 parts Solvent Ethyl acetate 20% Toluene 40% I.P.A. 16% total 100% * Oil Black HBB (Orient Chemical Industries Inc.) or Lanasyn Brown (Mitsubishi Chemical Industries Inc.) ** p-aminoacetanilide Example 2 The following is an example of an activating composition which may be used to re-activate a pattern which has been pre-printed using an oilsoluble dye, for example on a polyvinylalcohol film:: Alkyd resin (7 parts) and nitro cellulose (3 parts) 10+1.5% Plasticiser (dibutyl phthalate) 18+1.5% Precipitated barium sulphate 23+1.5% Butyl carbitol acetate 35+1.5% Butyl cellosolve 14+1.5% This composition has a viscosity of 1 5+1 sec (250C, lwata cup) and is suitable for application to the film by coating.

Example 3 A. Ink Composition Dye (oil type)* 30% Solvent Ethyl acetate 20% Toluene 30% I.P.A. 12% Resin containing 7 parts of cellulose nitrate and 3 parts of alkyd resin for fixing the pattern 8% B post-treatment bath (penetration promotion) Penetration promoting agent (O-phenylphenol) 0.1% Dispersing agent (Sunsalt 7000) 0.02% Disperse dye* 2% Water ,- 97.88% Y See Example 1 A pattern was first printed onto polyvinylalcohol film using the ink (A). While the ink was still wet, the pattern was transferred onto generally cubic shaped objects having curved surfaces. The transfer step was conducted in a water bath, using the apparatus described in British Patent Specification 1515325.The film was then removed by washing with water and the printed objects were then subjected to a pene tration promoting post treatment by immersion in a bath containing an aqueous emulsion of composition (B) for 10 minutes at 50800. The objects were then washed with water and dried.

Excellent results were obtained with objects made of cellulose propionate, acrylonitrilebutadiene styrene copolymer and nylon, and good results with objects made of acrylic resin and polyvinyl chloride. Objects made of cellulose acetate, epoxy resin or polypropylene may be printed by the same method.

These tests showed that the printed pattern will not peel off and the pattern is less subject to wear since the dye of the printing ink intrudes into the surface of the object, and furthermore a final coating process is unnecessary. The method provides an attractive effect in that the pattern is integral with the object.

Claims

1. A method of applying a pattern to an object made of an organic polymeric material by transfer printing, which comprises: a) providing a water-swellable film having a transfer pattern printed thereon with a nonaqueous ink which comprises a solution or dispersion of a water-insoluble dye and a resin which fixes the pattern in an organic solvent, b) placing the film on the surface of the water in a water bath, with the transfer pattern face up, c) bringing the object into contact with the film by partially or completely immersing the object in the bath, the surface of the object at least in the area contacted by the pattern being penetrable by the ink, d) allowing the ink to penetrate into the surface of the object to form the pattern therein, and e) removing the film from the object.

2. A method as claimed in claim 1 wherein the water-swellable film having the transfer pattern printed thereon is provided by applying an activating composition comprising the organic solvent and pattern-fixing resin to a film onto which the desired pattern has been pre-printed with the dye.

3. A method as claimed in claim 1 or claim 2 wherein the film is a polyvinylalcohol film.

4. A method as claimed in any one of the preceding claims wherein said ink contains 130% by weight of said dye and 1020% by weight of the resin.

5. A method as claimed in any one of the preceding claims wherein the pattern-fixing resin is an alkyd resin or nitrocellulose or a mixture thereof.

6. A method as claimed in any one of the preceding claims wherein the film is removed by washing the printed object with water after being removing from the water bath.

7. A method as claimed in any one of the preceding claims wherein the printed object is subjected to a post-treatment step after being removed from the water bath to promote penetration of the ink into the surface of the object.

8. A method as claimed in claim 7 wherein the post-treatment is effected by immersing the printed object in an aqueous emulsion of a solvent for the polymeric material of the object.

9. A method as claimed in any one of the preceding claims wherein the object is dyed before or after the pattern is applied.