BACKGROUND OF THE INVENTION
1. Field of the Invention
The indention relates to a coating method, more particularly to a method for coating a knitted fabric.
2. Description of the Related Art
Fabrics, based on their structures, can be generally divided into the following categories: woven fabrics, knitted fabrics and non-woven fabrics. As shown in FIG. 1, a woven fabric 91, which is formed by weaving a warp yarn 911 with a weft yarn 912 utilizing a weaving machine, has relatively high mechanical strength but low elasticity in comparison to the knitted fabrics. On the other hand, as shown in FIG. 2, a knitted fabric 92, which is formed by knitting a yarn 921, has relatively high elasticity but low mechanical strength.
When the woven fabric 91 needs to be coated with a functional coating layer 51 to attain various functions (such as water-resistance or breathability), a coating machine 6 (see FIG. 3) can be utilized, where the woven fabric 91 is driven by rollers 61 to pass through a distribution device that distributes a functional coating material 5 so as to form a coating layer 51 on the woven fabric 91. Since the woven fabric 91 has relatively high mechanical strength, deformation of the woven fabric 91 does not occur. However, such method is not suitable for the knitted fabric 92 due to the high elasticity thereof. That is, when the knitted fabric 92 passes through the coating machine 6, it will be stretched by the driving rollers 61 along either one of warp or weft directions. After the knitted fabric 92 is coated with the coating layer 51 and is released by the rollers 61, the knitted fabric 92 may shrink which causes the coating layer 51 to be uneven. Besides, when distributing the functional coating material 5 onto the knitted fabric 92, the weight of the functional coating material 5 would cause the knitted fabric 92 to deform, thereby resulting in the uneven formation of the coating layer 51.
Referring to FIG. 4, another conventional method for forming the coating layer 51 on the knitted fabric 92 is illustrated to include the steps of: distributing and drying a coating material 5 on a release film 7 so as to form a coating layer 51 thereon; distributing an adhesive 8 to form an adhesive layer 81 on the knitted fabric 92; and attaching the coating layer 51 onto the adhesive layer 81, followed by removing the release film 7. Such method may alleviate the aforesaid problem but results in a relatively complicated process (e.g., the adhesive layer 81 and the coating layer 51 need to be aligned before bonding) and relatively low production efficiency.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a coating method that may alleviate the aforementioned drawbacks of the prior art.
Accordingly, a method of the present invention for coating a knitted fabric includes the following steps of:
(a) attaching a knitted fabric flatly onto a carrier sheet to form a laminate, the carrier sheet having a tensile strength greater than that of the knitted fabric;
(b) forcing a coating layer onto a top surface of the knitted fabric; and
(c) separating the knitted fabric with the coating layer from the carrier sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
FIG. 1 is a schematic perspective view of a woven fabric;
FIG. 2 is an enlarged schematic elevation view of a knitted fabric;
FIG. 3 is a schematic diagram, illustrating a conventional method for coating a woven fabric using a knife-over-roll coating machine;
FIG. 4 is a schematic diagram, illustrating another conventional method for coating the knitted fabric;
FIG. 5 is a flow chart of the preferred embodiment of a method for coating a knitted fabric according to the present invention;
FIG. 6 is a schematic diagram, illustrating a step of attaching a knitted fabric onto a carrier sheet to form a laminate of the preferred embodiment;
FIG. 7 is a schematic diagram, illustrating a step of trimming edges of the laminate of the preferred embodiment; and
FIG. 8 is a schematic diagram, illustrating a step of forming a coating layer onto a top surface of the knitted fabric of the preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 5 to 8, the preferred embodiment of a method for coaling a knitted fabric 1 according to the present invention includes the following steps.
Step 401: attaching the knitted fabric 1, which remains unstretched, flatly onto a supporting surface 21 of a carrier sheet 2 (see FIG. 6) to form a laminate. The carrier sheet 2 has a tensile strength greater than that of the knitted fabric 1. As depicted in FIG. 6, the knitted fabric 1 is bonded to the carrier sheet 2 using adhesives 3, but other approaches, such as sewing or high-frequency thermal bonding, may also be used to combine the carrier sheet 2 and the knitted fabric 1 to form the laminate. In this embodiment, the carrier sheet 2 is a woven fabric having a dimension substantially the same as that of the knitted fabric 1. Nevertheless, the dimensions and the configuration of the carrier sheet 2 are not limited to what are disclosed in this embodiment according to the present invention. For example, the dimension of the carrier sheet 2 can be slightly greater than that of the knitted fabric 1.
Step 402: trimming and thermal-treating edges of the knitted fabric 1 (see FIG. 7), so as to prevent loose threads at the edges of the knitted fabric 1 that would adversely affecting the following coating process.
Step 403: directly forming a coating layer 51 on a top surface of the knitted fabric 1, which is opposite to the supporting surface 21 of the carrier sheet 2 (see FIG. 8). The coating layer 51 is composed of a functional coating material 5 that is selected from the group consisting of polyurethane resin, polymethylmethacrylate resin, rubber, pigment, polyvinylchloride adhesive, colored adhesive, waterproof breathable adhesive, and combinations thereof. In this embodiment, as shown in FIG. 8, Step 403 is conducted by passing the laminate through a knife-over-roll coating machine 6, wherein the laminate is driven by at least one roller 61 to pass through the coating machine 6, so as to perform steps of distributing the coating material 5, removing excess amount of the applied coating material 5 (by a knife) and drying the coating material 5 to form the coating layer 51. However, it should be noted that the formation of the coating layer 51 should not be limited to use of the knife-over-roll coating process only. For example, utilizing blade coating process, roller coating process or foam coating process in the formation of the coating layer 51 would also suffice in accordance with the present invention.
It is worth noting that when the functional coating material 5 includes water-borne components, the foam coating process, which includes steps of mixing thoroughly the coating material 5 with air to form coating foam and applying the coating foam onto the knitted fabric 1, is preferred. Such foam coating process can reduce the water content of the functional coating material 5 and effectively increase the drying speed of the coating layer 51, so as to lower the energy consumption as well as the production cost. In the meantime, since the coating foam exhibits relatively low mobility to permeate through the knitted fabric 1, such material is specifically suitable in one-side coating applications such as coloring and the like.
It is also worth noting that a plurality of the coating layers 51, which are composed of various functional coating materials 51, can be sequentially formed on the knitted fabric 1 by performing Step 403 repeatedly. In addition, Step 403 can also be conducted manually instead of utilizing the coating machine 6.
Step 404; separating the knitted fabric 1 with the coating layer 51 from the carrier sheet 2 to obtain a coated knitted fabric.
By utilizing the carrier sheet 2, which provides the laminate a relatively high mechanical strength in comparison to the knitted fabric 1 per se, deformation of the knitted fabric 1 does not occur along either one of warp and waft directions upon distributing the functional coating material 5 thereon. In addition, since the knitted fabric 1 is disposed on the supporting surface 21 of the carrier sheet 2, the carrier sheet 2 provides sufficient mechanical support for the knitted fabric 1 to prevent deformation caused by the weight of the functional coating material 5 during the step of forming the coating layer 51, so that the thickness of the coating layer 51 can remain constant.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. What is claimed is;
Patent Application
20160017527
