A METHOD OF PRODUCING A THREE DIMENSIONAL PROFILE IN A BODY

Abstract: A method of producing a three-dimensional profile on an exterior surface of a lamina in a body (10). The body (10) comprises a stretchable layer (1) bonded over substantially all of an outer surface of a thermoplastic layer (2), the inner surface of thermoplastic layer (2) being covered by a nylon third layer (3). The thermoplastic layer (2) comprising polyethylene foam substantially 0.008 m thick before thermoforming. The stretchable layer (1) comprising knitted material which is capable of stretching about 80 % in length and width. The method comprising: a) bonding together substantially all of the stretchable layer (1) to the outer surface of the thermoplastic layer (2) and bonding the inner surface of the stretchable layer (2) to the nylon third layer (3), to produce the lamina body (10) in a substantially flat form; b) silk screen printing a deformed image onto the outer surface of the stretchable layer (1); c) heating the thermoplastic layer (2) to about 200 DEG C in approximately 10 seconds; d) moulding the body (10) in an unheated aluminium mould for approximately one minute. The method being such that the angle of the exterior surface of the body (10) relative to a flat plane is capable of varying sharply to produce a highly defined profile.

Description: A method of producing a three-dimensional profile in a body The present invention relates to a method of producing a three-dimensional profile on an exterior surface of a body, which body is resilient and comprises a thermoplastic layer and a stretchable layer, and to the product of the method. It is known to mould thermoplastic into particular predetermined shapes, and it is further known to cover the thermoplastic with a layer of material. However, the known methods of making three-dimensional bodies of this type are limited in that the bodies which are formed cannot display complex or intricate profiles. Previously, if a three- dimensional profile with a complex or intricate profile was required, it was necessary to use injection moulding techniques. However, an injection moulding techniques could not produce articles with the look and feel of a thermoformed article. According to the present invention there is provided a method of producing a three-dimensional profile on an exterior surface of a body, which body comprises a thermoplastics layer and a stretchable layer bonded to the exterior surface; the thermoplastics layer being thermoformed in a mould to produce the profile; the stretchable layer being such and being bonded over substantially the entire exterior surface of the thermoplastics layer, in such a way that the profile formed is highly defined. The profile formed by the method of the present invention is capable of displaying sharp contours with the angle of the exterior surface changing greatly over a short distance of the surface. This enables the profile to be very detailed, that is highly defined. The precise thermoplastic used will vary depending upon the physical conditions employed during the thermoforming process. The thermoplastic must be of such a type that it can be moulded to the exact profile of the mould and after it has been moulded, the thermoplastic must be removable from the mould without permanent deformation of the profile formed by the mould. Preferably, when thermoforming process forms the profile, and the mould is removed, the thermoplastic is permanently deformed and does not have a tendency to spring into another shape. Preferably, the thermoplastics layer is a foam, preferably having a nominal density of between 20 and 40 Kg m 3 , preferably between 29 and 36 Kg m 3 , and in a preferred embodiment 33 Kg m 3 , and the foam has a thickness of between 5 and 11 mm, preferably 8 mm, prior to moulding. The foam is preferably made of polyethylene. Preferably, the thermoforming technique comprises a low- temperature process, wherein the thermoplastics layer is only heated to between 180°C and 220°C, preferably 200°C. Preferably, the thermoplastics layer is preheated to its optimum temperature, before being placed in the mould for approximately ten seconds. The profile is formed within a mould in approximately one minute, the mould itself preferably being unheate . The stretchable material is preferably an elastomeric material. The elastomeric material maybe lycra ® (registered Trade Mark of DuPont) and may have a density between 50 and 250 g m ~2 . A third layer of material may be bonded to the face of the thermoplastics layer opposite from the stretchable layer. The third layer may be made from non-woven polypropylene which can weigh between 400 and 200 gm m -2 . Alternatively, the third layer may be made from Nylon 6, 6. The third layer of material may be used to mount the body onto another article such as a bag or an article of clothing. It is often preferable to have all the stretchable layer and the third layer bonded to the thermoplastics layer to form a lamina prior to the thermoplastics layer being thermoformed. In a preferred embodiment the lamina is made before the stretchable layer is printed. In order to prevent the bonding between layers deteriorating during thermoforming, and that the stretchable layer does not adhere to the mould or be stretched in such a way to cause distortion of the desired profile after the body has been removed from the mould. In order to achieve adequate bonding between the thermoplastic layer and the stretchable layer so that a high definition profile is formed, the angle of the warp and weft of the stretchable material must correspond to the surface structure of the thermoplastic layer. In the case where the thermoplastics layer comprises polyethylene foam and stretchable layer comprises lycra ® (registered Trade Mark of DuPont) . Preferably, the stretchable layer is knitted and is preferably formed os a polyester/lycra ® mix. The polyester may exceed 50% of the mix. In a preferred embodiment the lycra ® is made from, approximately, 91.75% Polyester and 8.25% Lycra ® , ± 5% The material weighs between 140 and 180 gms m ~2 , preferably 160 gms irf 2 and has about 28 CPC (Courses Per Centimetre) and about 16 PC (Wales Per Centimetre) . The stretchable material is capable of stretching, approximately, 80% in length or width. Preferably, a coloured image, such as a cartoon face, is formed on the profile. This image may be formed on the stretchable layer after the stretchable layer is bonded to the thermoplastic layer and before moulding. The image may be formed with silk screen printing. The image formed by the silk screen printing may be deformed from the image that is desired on the profile, so that when the profile is formed by moulding the relative distance between these parts of the image are altered from the flat screen print, to produce the desired image in three-dimensions on the profile. Alternatively the image may be applied to the body after the profile is formed by spraying or painting. Preferred embodiments of the invention will now be described by way of example, with reference to the attached drawing, where: Figure 1, depicts a sectioned side view of a body formed by the present invention, attached to another article. The body (10) includes a sheet-like layer in the form of a thermoplastic member, being deformed so to have a three- dimensional profile with an interior and an exterior surface, and is adapted to be attached to another article (5) about its periphery (4). The inside layer (3) of non-woven polypropylene is glued to the exterior surf ce of the body (5) . The thermoplastic layer (2) is moulded to produce a high definition profile on its exterior face (2a). A stretchable layer (1) is connected to substantially all the thermoplastic layer and displays a high definition surface (la). Elastomers, such as lycra ® , are used as the stretchable layer, as this fabric has very consistent and precise waft and weft angles which allow it to be bonded to the foam even after the foam (2) has been moulded to produce highly defined contours on its exterior surface (2a). The stretchable layer and the third layer are bonded to the thermoplastic layer before the profile is formed in the thermoplastics layer. To form the highly defined profile: 1) A flat layer (2) of the foam is covered on one side with lycra ® layer (1) and on the other side with a third layer (3), to form a flat laminate (10). The three layers (1, 2, 3) are adhered by means of a glue. The glue must have the ability of stretching with the two layers of material whilst maintaining the adhesion between the layers, for example XI O. 2) A deformed image is printed onto the laminate by a silk screen process. The process involves placing a mask which over the laminate (10) and using a vacuum bed to adhere the mask to the laminate which needs to be sprayed. The deformed image is applied by spraying through the mask. It is also possible to use ta po (pad) printing, vacuum spraying, heat transfer, cold transfer, dye-sublimation or multi-colour thermoform printing methods, but techniques which involve rollers and/or pressing have been found not to work. It should be noted that the inks used in applying the deformed image cannot be dried by heat treatment as this would lead to distortion of the laminate due to expansion of materials therein, but the inks must also be stable during the ensuing thermoforming process. 3) The laminate (10) in then heated in a jig in order that the foam layer (2) reaches a high enough temperature to be thermoformed, normally about 200°C. 4) The heated laminate (10) is then placed in a press. The laminate (10) is then pressed between a mould, with the female mould on the lycra ® layer (1) side of the laminate (10) and the male mould on the third layer (3) side of the laminate (10). The female mould produces an exterior three-dimensional image in the laminate (10). The male mould may be shaped to be an exact match for the female mould, or may comprise a substantially flat surface, or may comprise a substantially flat surface with opening that allow through projections) to apply pressure to certain area(s) of the laminate during the pressing of the mould, approximately one minute. The foam layer (2) expands when heated in the thermoforming process described above. The foam layer (2) expands mainly in one direction, but other expansions and/or contractions of the layer will normally also occur. Also, the lycra ® layer (1) will stretch with the expansion of the foam layer (2). The present process produces a three-dimensional profile with a printed image. The various colours of the printed image in the finished article are required to be over certain predetermined parts of the three-dimensional profile. Therefore the deformed image printed on lycra ® layer (1) of the laminate (10) is such that when foam layer (2) expands/contracts during the thermoforming process and the lycra ® layer (1) stretches the image is contorted so that the required colours are precisely over the predetermined parts of the three-dimensional profile. In order to calculate the required deformed image for any particular three-dimensional profile with a predetermined colour pattern, it is necessary to precisely calculate all the expansions and contractions which occur to the flat laminate (10) during the thermoforming process. It will also be realised that the lycra ® layer (1) must not slip over the foam layer (2) during the thermoforming process and so the glue used between the layers must retain its adhesivity during the process. Also, the orientation of the lycra ® layer (1) in relation to the foam layer (2) must be predetermined, both before and after the deformed image is applied, so that the expansion/contraction of the foam layer (2) occur in the calculated directions and magnitudes. Finally the laminate (10) must be pressed in the mould in a predetermined precise orientation so that the finished article has good definition in that the colours are precisely over the predetermined area of the three-dimensional profile. Normally, the mould is made from cast aluminium. The inks used in this process are such that they do not stick to the mould, even when heated in the thermoforming process. The body (10) will often have upto seven colours in precise areas of the three-dimensional profile. In this invention the following material may be used: Fabric a) Stretchable layer fl) of Fabric. The fabric will be based on either Nylon Lycra ® or Polyester Lycra ® . Weight of material 50/250 gm per square metre. For example: White Polyester Lycra ® . Composition: Polyester 91.75% Lycra ® 8.25% Weight: 160 gms/m 2 (nominal) Course per cm 28 Wales per cm 16 Stretch: Length: 80% Width: 80% with a 3 kg load on an extensometer. hi Third layer (3) of fabric. Non-woven polypropylene, weight from 400 to 200 gm per square metre or similar. For example: Nylon - Black or White Composition: Nylon 66 100% Courses per cm 18 Wales per cm 17 Stretch: Length: 60% Width: 180% with a 3kg load on an extensometer. c] Foam layer ( 2 ) The foam is expanded polyethylene foam, with Density range of 24 to 50 kg m 3 , preferably 29 to 36 kg m 3 . For example, the foam is a closed Cell Cross linked expanded Polyethylene foam, with nominal density 33 kg 3 and thickness prior to moulding 8 mm. Alternatively, polyurethane, polyvinyl chloride or polypropylene foams can be used, all of which will have a similar density range to that described above. Adhesives The laminate will be flame retardant and will conform to BS5665 part 2, 1989. For example, adhesives which can be used: a) Between Lycra ® layer and foam layer XIRO -2060 - 30 gsm b) Between the nylon third layer and foam layer XIRO - 2000 - 25 gsm Printing Inks The printing inks or spraying inks will conform to E.C. standard and will be to non-toxic nature. For example: SERICOL Black Flexitex Red Flexitex HARLER Black Marlertex Red Marlertex Moulding The moulding is produced by Compression Moulding/Thermo- forming. Normally, the mould is not heated and the laminate (10) is heated prior to being moulded, which ensures that the aluminium mould does not stick to the laminate (10) . However, it would be possible to use a heated mould and heat the laminate (10) in the mould provided that suitable inks were used that would not adhere to the heated mould made form a suitable material. Obviously, a body made by this technique can be used in a number of different applications, such as images attached to bags and the like, the body could comprise the sole of a shoe. The body formed can be used anywhere that requires a high definition profile, which previously could only be formed by using thermosetting plastics or the like. The body formed in the invention is often attached to an article of clothing or a similar fabric item or bags, wallets or hats. In such circumstances it is very important that the body can be washed. Therefore, the choice of dyes or inks used in applying the image is limited, as fading of the image must be minimised forr the article to be commercially acceptable. Also, the materials from which the body is made must not shrink or lose shape when washed. It is preferred that the bodies conform with the relevant British Standard specification or equivalent Foreign country requirement. In the embodiments described above, the bodies have been tested and found to be meet the required standards. The recommended washing and other care instructions being: to wash as a synthetic at 40°C, Do Not Bleach, Do Not Tumble Dry, Do Not Iron. Also, the bodies should be able to withstand mechanical and physical abuse. The described embodiment has been tested in accordance with British Standard BS5665, Parts 1 and 2, and has passed the required tests.

Claims: Claims 1. A method of producing a three-dimensional profile on an exterior surface of a lamina body (10), the method comprising bonding a stretchable layer (1) over substantially all of an outer surface of a thermoplastic layer (2) , the thermoplastic layer (2) being thermoformed in a mould to produce the profile, the method being such that the angle of the exterior surface relative to a flat plane is capable of varying sharply to produce a highly defined profile (6) . 2. A method according to claim 1, wherein the body (10) includes a third layer (3) comprising non-woven polypropylene; the thermoplastic layer (2) comprises polyethylene foam; the stretchable layer (1) is knitted; characterised in that the method comprises: a. a deformed image is printed onto the stretchable layer (1) by a silk screen process; b. bonding the stretchable layer (1) to the exterior surface of the thermoplastic layer (2) and bonding the third layer (3) to the inner surface of the thermoplastic layer (2), thereby forming the body (10); c. heating the thermoplastic layer (2) to approximately 200 * C for approximately ten seconds; d. moulding the body (10) in an unheated mould for approximately 1 minute, whereby the deformed image is transformed into a desired image. 3. A method according to claim 1 or claim 2, wherein the thermoplastic layer (2) is substantially 0.008m thick before thermoforming and has a density of substantially 33 Kg m "3 ; the stretchable layer (1) is capable of stretching substantially 80% in length or width and comprises, approximately, 91.75% Polyester and 8.25% Lycra ® and weighs substantially 0.16 Kg m~ 2 ' and the stretchable layer (1) has substantially 28 CPC (Courses per centimetre) and about 16 WPC (Wales per centimetre); the third layer (3) weighs between 0.2 and 0.4 Kg 4. A method of producing a three-dimensional profile on an exterior surface of a body (10) according to claim 1 or claim 3, wherein the stretchable layer (1) is bonded to the thermoplastic layer (2) before the thermoplastic layer (2) is thermoforme . 5. A method of producing a three-dimensional profile on an exterior surface of a body (10) according to any one of claims 1, 3 or 4, wherein the thermoforming process comprises a low- temperature process in which the thermoplastic layer (2) is heated to between 180°C to 220°C, preferably 200°C. 6. A method of producing a three-dimensional profile on an exterior surface of a body (10) according to any one of claims 1, 3, 4, or 5, wherein thermoplastic layer (2) is preheated to its optimum temperature, before being placed in the mould for approximately ten seconds. 7. A method of producing a three-dimensional profile on an exterior surface of a body (10) according to any one of claims 1, 3, 4, 5, or 6, wherein the profile is formed within a mould in approximately one minute, and the mould is unheated. 8. A method according to anyone of the preceding claims, wherein, during the said thermoforming process, the stretchable layer (1) does not to adhere to the mould and is not stretched in such a way to cause distortion of the desired profile after the body (10) has been removed from the mould. 9. A method according to any one of claims l or 3 to 8, wherein the third layer (3) is bonded to the thermoplastics layer prior to the thermoplastics layer being thermoformed. 10. A method according to any one of claims 1 to 9, wherein the desired image comprises a coloured image, such as a cartoon face, formed on the non-bonded surface of the stretchable layer. 11. Amethod according to claim 10, wherein the deformed image is formed before the stretchable layer (1) is bonded to the thermoplastic layer (2). 12. A method according to claim 10 or claim 11, wherein the said image is produced by silk screen printing. 13. A method according to claim 12, wherein the deformed image printed onto the stretchable layer (1) is transformed into said desired image after the said thermoforming process. 14. A method according to claim 10, wherein the image is formed after the body (10) has been moulded by spraying or painting. 15. A body (10) including a three-dimensional profile on an exterior surface of the body (10), which body (10) comprises a stretchable layer (1) and a thermoplastic layer (2) which includes an inner and an outer surface, the thermoplastic layer (2) being thermoformed in a mould to produce the profile, wherein the stretchable layer (1) is bonded over substantially the entire outer surface of the thermoplastics layer and the profile is adapted so that the angle of the profile relative to a flat plane is capable of varying sharply (6). 16. A body (10) according to claim 15, wherein the thermoplastic comprises a foam which, subsequent to the removal of the mould, retains the precise shape foamed in a mould during the thermoforming process. 17. A body (10) according to claim 16, wherein the foam has a density of between 20 and 40 Kg m "3 , preferably 33 Kg m" 3 . 18. A body (10) according to claim 16 or 17, wherein the thermoplastic layer (2) is between 5 and 11 mm thick, preferably 8 mm thick, prior to being thermoformed. 19. A body (10) according to any one of claims 16 to 18, wherein the foam consists of polyethylene. 20. A body (10) according to any one of claims 15 to 19, wherein the stretchable layer (1) includes an elastomeric material. 21. A body (10) according to claim 20, wherein the elastomeric material is Lycra ® (registered Trade Mark of Dupont) . 22. A body (10) according to claim 21 or claim 22, wherein the elastomeric material has a density between 50 and 250 gm irf 3 . 23. A body (10) according to any one of claims 20 to 22, wherein the stretchable layer (1) comprises an elastomeric material combined with a second material. 24. A body (10) according to claim 23, wherein the second material is a polyester. 25. A body (10) according to any one of claims 15 to 24, wherein the stretchable layer (1) is knitted or woven. 26. A body (10) according to claim 25, wherein the stretchable layer (1) is woven and the angle of the warp and weft of the stretchable material corresponds to the surface structure of the thermoplastic layer (2). 27. A body (10) according to claim 25, wherein the stretchable layer (1) is knitted and comprises a polyester/lycra ® mix, in which the polyester exceeds 50% of the mix. 28. A body (10) according to claim 27, wherein the said mix comprises, approximately, 91.75% Polyester and 8.25% Lycra ® . 29. A body (10) according to claim 27 or claim 28, wherein the stretchable material weighs between 140 to 180gms m „ " -2 preferably 160 gms m" 2 . 30. A body (10) according to any one of claims 27 to 29, wherein the stretchable material comprises substantially 28 CPC (Courses per centimetre) and about 16 WPC (Wales per centimetre) . 31. A body (10) according to any one of claims 15 to 30, wherein the stretchable material is capable of stretching substantially 80% in length or width. 32. A body (10) according to any one of claims 15 to 31, wherein the body (10) includes a third layer (3) of material bonded to the inner surface of the thermoplastic layer (2) . 33. A body (10) according to claim 32, wherein the third layer (3) is made from non-woven polypropylene which weighs between 400 and 200 gm m ~2 . 34. A body (10) according to claim 32 or claim 33, wherein the body (10) is connected via the third layer (3) to an article, such as a bag or an article of clothing. AMENDED CLAIMS [received by the International Bureau on 26 April 1993 (26.04.93); original claim 10 cancelled; original claims 1,11,12 and 14 amended; other claims unchanged (2 pages)] Claims 1. A method of producing a three-dimensional profile on an exterior surface of a lamina body (10), the method comprising bonding a stretchable layer (1) over substantially all of an outer surface of a thermoplastic layer (2), the thermoplastic layer (2) being thermoformed in a mould to produce the profile, characterised in that the angle of the exterior surface relative to a flat plane is capable of varying sharply to produce a highly defined profile (6) and a desired image of a plurality of colours is formed on the non-bonded surface of the stretchable layer (1) so that said colours are precisely over predetermined areas of the profile. 2. A method according to claim 1, wherein the body (10) includes a third layer (3) comprising non-woven polypropylene; the thermoplastic layer (2) comprises polyethylene foam; the stretchable layer (1) is knitted; characterised in that the method comprises: a. a deformed image is printed onto the stretchable layer (1) by a silk screen, process; b. bonding the stretchable layer (1) to the exterior surface of the thermoplastic layer (2) and bonding the third layer (3) to the inner surface of the thermoplastic layer (2), thereby forming the body (10); c. heating the thermoplastic layer (2) to approximately 200°C for approximately ten seconds; d. moulding the body (10) in an unheated mould for approximately 1 minute, whereby the deformed image is transformed into a desired image. 3. A method according to claim 1 or claim 2 , wherein the thermoplastic layer (2) is substantially 0.008m thick before thermoforming and has a density of substantially 33 Kg m~ 3 ; the stretchable layer (1) is capable of stretching substantially 80% in length or width and comprises, approximately, 91.75% Polyester and 8.25% Lycra ® and weighs substantially 0.16 Kg m~ 2 ' and the stretchable layer (1) has substantially 28 CPC (Courses per centimetre) and about 16 WPC (Wales per centimetre); the third layer (3) weighs between 0.2 and 0.4 Kg m-2. 10. Cancelled. 11. A method according to any one of claims 1 to 9, wherein the deformed image is formed before the stretchable layer (1) is bonded to the thermoplastic layer (2) . 12. A method according to any one of claims 1 to 9 or 11, wherein the said image is produced by silk screen printing. 13. A method according to claim 12, wherein the deformed image printed onto the stretchable layer (1) is transformed into said desired image after the said thermoforming process. 14. A method according to any one of claims 1 to 9, wherein the image is formed after the body (10)- has been moulded by spraying or painting. 15. A body (10) including a three-dimensional profile on an exterior surface of the body (10) , which body (10) comprises a stretchable layer (1) and a thermoplastic layer (2) which includes an inner and an outer surface, the thermoplastic layer (2) being thermoformed in a mould to produce the profile, wherein the stretchable layer (1) is bonded over substantially the entire outer surface of the thermoplastics layer and the profile is adapted so that the angle of the profile relative to a flat plane is capable of varying sharply (6) . 16. A body (10) according to claim 15, wherein the thermoplastic comprises a foam which, subsequent to the removal of the mould, retains the precise shape foamed in a mould during the thermoforming process.

Inventors: LITTLE GARY, LITTLE, GARY
Applicants: PRODUCTION EXPERTS LIMITED
Application year: 1992
Main classification: B29C51
IPC codes: B29C51