METHOD FOR APPLYING A PATTERN ONTO THERMOPLASTIC WORKPIECE AND AN OBJECT PRODUCED ACCORDING TO THE METHOD

Abstract: The present invention concerns a method for the application of a pattern on a work piece of thermoplastic material, preferably plastic, in which method a material, preferably fabric, carrying a predetermined pattern, is brought into contact against said work piece, that the plastic material is heated to a predetermined temperature, and that said patterned material is allowed to remain in contact with the plastic material for a predetermined time, so that the pattern is completely or partly taken up by the work piece, whereupon said pattern carrying material is removed, a method for the production of an object from the work piece with simultaneous application of the pattern, as well as an object produced according to the method.

Description: Method for applying a pattern on to a thermoplastic or piece and an object produced according to the method. The present invention concerns a method for applying a pattern onto a work piec made of thermoplastic material, shaping the work piece to make an object, as well as an obje produced by means of the method. It is known from US 4 202 663 how to transfer patterns to a object made of plasti i y pacing a polyolefin film between a colour transfer paper and a sheet of thermoplastic materia Heating takes place to a sufficient degree for the colour to sublimate through the plastic fil and the colour to be absorbed by the plastic sheet with possible pattern intact. The material subsequently cool down and are seperated whereby a decorated sheet is made. This colourin methos can also be used in connection with shaping of objects, so called "in-mold decoration" The disadvantage with this method is that several layers must be laid onto the article which i to be patterned and possibly shaped, and after the process these two layers must on the othe hand be discarded. The invention concerns more precisely a method, by which an object of thermoplasti material of the type polyethylene, polypropylene, polystyrene, ABS-plastic etc. is furnished wit a pattern at the same time as a possible shaping of the object takes place. The property, which makes thermoplastics usable in many situations, is the propert of these plastics becoming plastic when heated, which depends on the forces between the linea macromolecules in the plastics reducing at elevated temperatures. In this connection the plasti becomes more or less deformable under pressure. These plastics regain their original propertie when cooled to normal temperatures. The usual ways to shape these plastics are to vacuum for or press the material under pressure into or onto a mould and then let the plastic cool dow before the mould is taken away. Thermoplastics are used in many areas where shaping of materials to form object is an integral part. In orthopaedic technology different types of thermoplastics are used to produce rigid objects which are included in prostheses and other aids, i.e. they are rigid in comparison to soft parts made of fabric or another material. The object can e.g. consist of a brace or similar. The way to produce these objects consists mainly in that a mould, e.g. made o plaster, is made of the part in question, wherein this mould is individually adjusted to fit the person who will use the manufactured aid. Once the mould is produced the object is shaped from some thermoplastic materi e.g. one of the above mentioned plastics. This shaping takes place through heating up t thermoplastic material to the temperature at which the material in question can be shaped eit through vacuum forming or through the thermoplastic being laid over the prepared plaster mo and being shaped manually. The above named thermoplastic materials can be obtained either in uncoloured coloured state. Even if the material is functional and the objects which are produced functi satisfactorily, they often do not give a completely satisfactory visual impression. Especially wh the manufactured shaped objects are included in orthopaedic aids for children it would desirable to give the objects an aesthetically more attractive appearance. It has now surprisingly been shown that through heating up a thermoplastic w piece, letting it lie in contact with a patterned fabric, which naturally must withstand temperat received during the heating up without itself being destroyed, the pattern is transferred to t heated thermoplastic. The thermoplastic work piece in this method is preferably in the form a sheet. It is also conceivable to use as the pattern carrying material another heat resist material with properties corresponding to those of fabric. The fabric which during the heating up is brought into contact against the sh shaped plastic material is advantageously made of a stretch material e.g. lycra. The heating can take place in a press, in which heat can be applied from both or just one side. In o embodiment the pattern is applied through heating from the side against which the fabric is contact, i.e. the heat contributes to the pattern on the fabric migrating into the plastic mater with the heat. The reason why the fabric which is used in the method should be made of a stret fabric or similarly formable material provided with a pattern is that no part of the mater provided with a pattern shall move relative to the plastic during the forming process, i.e. crease or similar should arise. The shaping of the sheet shaped plastic work piece which is heat together with the fabric can e.g. take place through the work piece with the fabric being shap around a plaster mould or a mould of another material. With plaster moulds padding can attached as required to make the manufactured object more comfortable to wear. The paddi in itself is however not necessary to accomplish the method itself. The heated, sheet shaped wo piece is laid upon the padding, on the face facing away from the mould the material provid with a pattern is placed with the pattern around the plastic work piece. The plastic work pie is heated to approx. 200°C or the temperature appropriate for the respective plastic, so that it c be manually shaped around the padded plaster mould with the help of heat-resistant gloves. The plastic to subsequently allowed to cool and stiffen into its new shape. The shaping of the object can also take place by the plastic and the fabric lying in contact with the plastic being fixed in a frame, heated and placed over a mould, thereafter vacuum is applied and the plastic is shaped around the mould. Subsequently, the plastic is allowed to cool down. In the above shaping method the fabric is in contact with the thermoplastic the whole time during shaping and for a determined time after shaping. It has been shown that the transferring of the pattern to the thermoplastic is time dependent, i.e. the longer the time the pattern lies in contact against the plastic, the more of the colour from the pattern transfers to the plastic. The amount of penetration into the plastic is also a function of time and possibly also of the heating temperature. Once the desired level of pattern transfer has been reached the fabric is taken away from the shaped part. A further effect results from the use of the above described stretch material in that a simple structural influence is achieved on the usually shiny and smooth plastic material. This means that the manufactured part has an aesthetically attractive appearance and a tactually more pleasing surface, partly because of the transferred pattern and partly because the surface of the object is still indeed hard but because of the textured effect it gives a softer impression. It is of course possible to first give the object made from thermoplastic its final shape and then bring the deformable pattern carrying material into contact with the shaped object with simultaneous heating and letting the pattern be transferred with the latter process. In this connection, the time and process simplicity advantages which the above mentioned process permits, namely that the pattern carrying material during the shaping of the object displays a slight adhesion to the object and thereby a transfers its texture and the pattern point for point to the object, is not obtained. Further embodiments of the invention have the characteristics described in the sub- claims. The method according to the invention, which has been described above with reference to the described embodiments can, of course be modified within the frame of the attached patent claims with reference to the description.

Claims: CLAIMS 1. Method for the application of a pattern on a work piece of thermoplastic materi preferably plastic, characterised in that a material, preferably fabric, carrying a predetermin pattern, is brought into contact against said work piece, that the plastic material is heated to predetermined temperature, and that said patterned material is allowed to remain in contact wi the plastic material for a predetermined time, so that the pattern is completely or partly taken by the work piece, whereupon said pattern carrying material is removed. 2. Method according to claim 1, characterised in that the heating up of the plast material with the close lying pattern carrying material takes place in a press with heat appli from the side against which the pattern carrying material is lying close to. 3. Method according to any of the previous claims, characterised in that the patte carrying the material is deformable. 4. Method according to any of the previous claims, characterised in that the patte carrying material is a fabric, preferably a stretch fabric. 5. Method for manufacturing a shaped object from a work piece of thermoplasti material, preferably plastic, characterised in that a material, preferably fabric, carrying predetermined pattern, is brought into contact against said work piece, that the plastic materi is heated to a predetermined temperature, that the work piece is shaped to become said objec and that said patterned material is allowed to remain in contact with the plastic material for predetermined time, so that the pattern is completely or partly taken up by the work piec whereupon said pattern carrying material is removed. 6. Method according to claim 5, characterised in that the shaping takes place throug vacuum forming. 7. Method according to any of claim 5, characterised in that the shaping takes plac manually. 8. Object produced according to any of claims 1-5 characterised in that the object i formed from a work piece of thermoplastic material, preferably plastic against which work piece a material, preferably fabric, carrying a predetermined pattern, is brought into contact, that the plastic material with said pattern carrying material in contact is heated up to a predetermined temperature, that the work piece is shaped to form said object and that said patterned material remains in contact with the plastic material for a predetermined time, so that the pattern is completely or partly taken up by said object formed from the work piece, whereupon the pattern carrying material is removed. 9. Object according to claim 6, characterised in that the object is shaped by means of vacuum forming. 10. Object according to claim 6, characterised in to the object is shaped manually.

Inventors: HOLM URBAN, LINDH KJELL, LINDH LEIF, HOLM, URBAN, LINDH, KJELL, LINDH, LEIF
Applicants: HOLM URBAN, LINDH KJELL, LINDH LEIF, SCANDICARE PRODUCTS AB, HOLM, URBAN, LINDH, KJELL, LINDH, LEIF
Application year: 1995
Main classification: B29C51
IPC codes: B29C51, B41M5