EP4253624A1

EP4253624A1 - Knitted structures for sublimation printing

Info

Publication number: EP4253624A1
Application number: EP23165613.3A
Authority: EP
Inventors: Sandeep KANG
Original assignee: Fashion Uk
Current assignee: Fashion Uk
Priority date: 2022-03-30
Filing date: 2023-03-30
Publication date: 2023-10-04
Also published as: GB2617123A; GB202204524D0

Abstract

Sublimation printing of images onto textiles requires the substrate to be wholly or substantially polyester, whereas traditional knitwear is formed from yarns such as acrylic that are not receptive to sublimation printing. The invention provides a knitted structure that comprises a front layer (1) formed of a high-count polyester yarn (11) and a rear layer (2) formed of another yarn (12) of similar count, such as acrylic. A third, elastic yarn (13) is preferably knitted into the structure to link the front and rear layers (1, 2) together.

Description

Technical field

The invention relates to the field of knitted textiles. In particular, it relates to the formation of knitted garments in the style of traditional knitwear, which are suitable to receive images applied by sublimation printing. Traditional garments formed by this method include jumpers, cardigans, scarves, hats and gloves. Although the invention will be described in relation to knitted garments, it is equally applicable to other products produced by similar techniques, for example knitted toys or knitted covers that may be used to protect or insulate various articles.

Background of the invention

The method of sublimation printing has become very popular for decorating garments such as T-shirts because it has many benefits. These mainly consist of unlimited colour and detailing on the final product compared with traditional methods of screen printing, which have always been limited to the number of screens upon the machine.
The main limitation of the sublimation printing process is that it needs a substrate that is heavily based on polyester in order for the inks (or dyes) to transfer onto the end product. Ideally the fabric should be 100% polyester to ensure full transfer and bonding of the dyes and thereby give the desired vibrancy to the printed image.
T-shirts and similar garments are knitted with a fine yarn on circular jersey fabric machines. In contrast, traditional knitwear is typically made up from flat panels with selvage edges, which are knitted using coarse yarns on needle gauges between 5 and 12. (However, use of the present invention for finer knits is not excluded.) Traditional knitted garments rarely make use of polyester, the main yarns used across the market being acrylic or cotton blends, in addition to the more traditional wool. None of these are compatible with the sublimation method of printing, which has therefore not been used in this valuable sector of the clothing market. Instead, images on traditional knitwear are usually knitted into the product using a Jacquard process but the number of colours is limited by the number of different yarns that can be handled by the machine and the resolution of the image is limited by the relatively coarse gauge of the knitting machines used, which produce large stitches and consequently give the image a pixelated look.
To have a true 100% polyester knitted jumper or similar garment is not viable, as to have this at a gauge where it is classified as knitwear would be too itchy and not comfortable to the skin. Also, a heavy enough count of polyester is not readily available. The inventor has experimented with various blends of polyester with other yarns to be suitable to knit into a knitwear structure. Several different blends and knit methods were tried without success. It was found that the vibrancy of the printed images declines rapidly as the proportion of polyester falls below 100%.
The problem has been recognized in published patent application US 2016/0165990 A1 , which proposes a different solution, namely, to form a separate outer layer of knitted polyester to which an image is applied by sublimation printing. The outer layer is then attached, e.g. by sewing or gluing, to an inner layer that may be knitted acrylic or another material. According to the description in the patent application, the outer polyester fabric preferably has a thread count of at least 130 threads per square inch. Therefore it will look and feel very different from traditional knitwear and will clearly appear as a patch applied to the surface of the garment. It would be preferable to print the image on the knitted structure of the garment itself.

Summary of the invention

The invention provides a knitted panel, as defined in claim 1, and a garment that is knitted to incorporate the inventive panel.
It also provides a method of knitting a panel, as defined in claim 11, and methods of forming printed, knitted garments that make use of the inventive method.
The dependent claims define aspects of the invention that are preferred but not essential.
Except where the context requires otherwise, this specification uses the word "front" to identify the outer face of a garment when it is worn conventionally and the word "rear" is used to identify the inner face. It will be understood that knitted panels according to the invention may be used on any part of the garment including, for example, the back of a jumper, and that garments according to the invention may be made, printed, transported or stored in any orientation or in an inside-out configuration.

The drawings

Figure 1 is a schematic cross section through a knitted panel according to the invention.
Figure 2 is a schematic drawing of a knitted garment that incorporates a panel according to the invention.
Figure 3 is a diagram showing the set-up of a knitting machine for knitting a panel according to one embodiment of the invention.

The panel 4 shown in Figure 1 is knitted as a single structure using three types of yarn. A front layer 1 is formed wholly or substantially from a first yarn such as polyester and provides an outer surface that is receptive to the inks used in sublimation printing. A rear layer 2 is formed wholly or substantially from a yarn that forms the bulk of the knitted garment. A middle layer 3 links together the front layer 1 and the rear layer 2, the middle layer 3 being formed from a yarn that has good elastic properties, such as elastane.
The first yarn, which is used principally in the front layer 1, is preferably 100% polyester but it may be a blend containing a high proportion of polyester, provided that such a blend is receptive to the inks used in sublimation printing. If other yarn materials are found or developed to receive such inks satisfactorily, or if new sublimation printing inks are developed that can be received satisfactorily by existing yarn materials, then those alternative yarn materials may be used in the invention instead of polyester or in combination with it. The yarn is preferably 3-ply to provide a heavy count that is compatible with traditional knitwear garments. However, the same inventive concept can also be used for knitting on a finer gauge of machine, when 3-ply yarn will not be required and finer counts of yarn can be utilised.
The second yarn, which is used principally in the rear layer 2, may be a conventional yarn that is used in knitwear, such as acrylic or an acrylic-cotton blend, though other yarns such as wool or blended compositions are not excluded. It does not need to be receptive to sublimation printing inks so typically will not contain a high proportion of polyester but polyester blends are not excluded. The second yarn is normally also used to form elements of the garment other than the panel according to the invention so the criteria for its selection can be determined by wider factors such as the overall look, feel, price and durability that are desired for the garment as a whole.
The counts of the first and second yarns are preferably substantially equal to facilitate knitting them together in a single structure and so that the finished garment has a unity of look and feel.
The elastic yarn of the middle layer 3 links together the front layer 1 and the rear layer 2 in a manner that accommodates differences between them in the degree of stretch, resulting from their different yarns. The third yarn of the middle layer 3 preferably picks up alternate stitches of the front and rear layers 1,2 as described in more detail below. After the panel 4 has been knitted, heat may be applied, for example using a steam bed, to cause the third yarn to contract and bind the front and rear layers 1,2 more closely together so that they behave as a single layer in the finished garment.
As illustrated, the front layer 1 and the rear layer 2 are completely distinct from one another, being linked only by the yarn of the middle layer 3. However, it is not excluded that some of the second yarn could be brought into the front layer 1, provided that the amount of the second yarn exposed on the outer face of the front layer does not degrade the quality of the printed image. It is also not excluded that some of the first yarn could be brought into the rear layer 2 provided that the amount of the first yarn incorporated in the rear layer does not adversely affect its properties, e.g. by the polyester fibres causing itchiness on the skin of the wearer. In some embodiments of the invention, if the front and rear layers 1,2 are linked together by the first and/or second yarns in this way, then the middle layer 3 may be unnecessary.
The front layer 1 is typically formed as a plain knit to provide the smoothest possible surface to receive the sublimation-printed image and allow its fine detail and subtle colours to be resolved. For the same reason, a white or pale-coloured yarn will normally be used for the front layer 1. However, other colours or structures could be used to achieve particular effects. For example, if a textured knitting structure such as ribbing is used, then only the outermost parts will receive the printed image and, when the knitted fabric is stretched to reveal the areas between the ribs, those areas can display a different colour or image formed by the yarn itself.
Figure 2 shows just one example of how a knitted panel 4 according to the invention may be incorporated into a knitted garment: in this case, a traditional Christmas jumper 5. An area on the chest of the jumper 5 is formed by the three-layer panel 4 so that an image can be sublimation-printed onto the front face of the panel 4. Other areas of the jumper, including the waist, neck and sleeve areas are knitted from the second yarn in a conventional structure.
It is preferred that the knitted panel 4 according to the invention should be formed in a continuous process with the knitting of the other parts of (at least) the front of the jumper. A typical commercial knitting machine having 8 to 16 feeds can easily accommodate the three feeds needed for the first, second and third yarns of the present invention, leaving room for multiple other yarns, e.g. of different colours, to be used for the remainder of the garment. The front, back and sleeves of the jumper may be knitted as separate pieces, which may subsequently be sewn together to make up the finished garment in a conventional manner. It is similarly possible for the panel 4 according to the invention to be knitted as a separate piece and then sewn in when the garment is made up. However, the layers of the panel 4 will always be knitted in a single operation and the knitted panel will occupy the full thickness of the finished garment, rather than being attached to the outside of the garment.
If the garment is made up from separate pieces, then it will generally be simpler to carry out the sublimation printing of the panel 4 prior to make-up. If the panel 4 has textured areas of knitting alongside it, then it is preferred to place a silicone mat of matching shape behind the panel during the printing process. This relieves the textured areas from the high pressure that must be applied to the panel during printing.
Preferably the garment panel according to the invention is knitted on machines with gauges in the range 5 to 12. For example, 7-gauge machines are suitable for producing an acceptable middleweight fabric. For finer gauges, the application of printing inks would adversely affect the "fine knit" feel of the fabric. For coarser gauges, the gaps that open between adjacent courses of stitching as the fabric stretches would become noticeable in the printed image.
The diagram in Figure 3 shows the set-up of a flatbed knitting machine - in this case a 7-gauge machine operated using a technical knitting program by Stoll° - to produce part of a three-layer panel according to one embodiment of the invention. Each horizontal band in the diagram represents one course of yarn. The knitting machine carries three yarns on each traverse, namely the first yarn 11 that forms the front layer 1 of the panel 4, the second yarn 12 that forms the rear layer 2, and the third yarn 13 that forms the middle layer 3. Therefore a set of three horizontal bands in the diagram represents a single traverse of the machine and a single course of knitting in the finished panel 4.
It can be seen that the first yarn 11 (in this instance 100% polyester) knits across every needle on the front of the bed and the second yarn 12 (in this instance acrylic) knits across every needle on the rear of the bed. However, the third yarn 13 (e.g. elastane) of the middle layer only knits on alternate stitches and, of those stitches, it knits alternately on the front and rear beds. For example, on one traverse 14, the third yarn 13 may knit needle 1 on the front bed, needle 3 on the rear bed, needle 5 on the front bed, needle 7 on the rear bed, etc. The next traverse 14' is the same, except that the third yarn is offset by one stitch to knit needle 2 on the front bed, needle 4 on the rear bed, needle 6 on the front bed, needle 8 on the rear bed, etc. Successive traverses are similarly offset until four traverses have been completed, when the cycle repeats. This pattern achieves an even distribution of the third yarn 13 across the stitches of the front and rear layers 1,2. However, alternative patterns may be used, as will be apparent to a knitting technician.

Claims

A panel (4) knitted from a first yarn (11) that is receptive to sublimation printing and a second yarn (12) that is not receptive to sublimation printing, the panel (4) being knitted in a structure that comprises a front layer (1) formed wholly or substantially of the first yarn (11) and a rear layer (2) from which the first yarn (11) is wholly or substantially absent.
A knitted panel (4) according to claim 1, wherein the first yarn (11) is polyester or a blend high in polyester.
A knitted panel (4) according to claim 1 or claim 2, wherein the second yarn (12) is acrylic or a blend high in acrylic.
A knitted panel (4) according to any preceding claim, wherein the counts of the first and second yarns (11, 12) are substantially equal.
A knitted panel (4) according to any preceding claim, further comprising a third yarn (13) that is knitted into the structure to link the front layer (1) and the rear layer (2) together.
A knitted panel (4) according to claim 5, wherein stitches of the third yarn (13) pick up stitches of the front and rear layers (1, 2).
A knitted panel (4) according to claim 6, wherein stitches of the third yarn (13) pick up stitches of the front and rear layers (1, 2) alternately.
A knitted panel (4) according to any of claims 5 to 7, wherein the third yarn (13) is more elastic than the first and second yarns (11, 12), and is optionally elastane.
A knitted garment (5), the garment being knitted in a structure that comprises a knitted panel (4) according to any preceding claim.
A method of knitting a panel (4) from a first yarn (11) that is receptive to sublimation printing and a second yarn (12) that is not receptive to sublimation printing, the method comprising knitting the yarns (11, 12) into a structure that comprises a front layer (1) formed wholly or substantially of the first yarn (11) and a rear layer (2) from which the first yarn (11) is wholly or substantially excluded.
A method according to claim 10, further comprising knitting a third yarn (13) into the structure to link the front layer (1) and the rear layer (2) together.
A method according to claim 11, comprising using stitches of the third yarn (13) to pick up the front and rear layers (1, 2) alternately.
A method according to claim 12, comprising, on one course of knitting, stitching the third yarn (13) on needles that are offset relative to the immediately preceding course.
A method of forming a printed, knitted garment (5), comprising:
knitting a garment (5), including using the method of any of claims 10 to 13 to knit a panel (4) in the garment; and

using a sublimation printing process to apply an image to the front layer of the panel.
A method according to claim 14, further comprising supporting the panel (4) on a mat during the sublimation printing process.