1. Field of the Invention
The present invention relates to a method for manufacturing a polyurethane (P.U.) product with high wetting ability, gas permeability and high water repellent ability by means of a dry transfer coating process.
2. Description of the Related Art
A conventional dry type direct coating method in accordance with the prior art shown in FIGS. 1 and 2 is used for manufacturing a synthetic cloth and comprises directly coating a P.U. surface layer 20 on a substrate cloth 10 which is a knitting cloth, a non-woven cloth, intersecting knitting cloth or the like, thereby making the synthetic cloth which includes the P.U. surface layer 20 and the substrate cloth 10 as shown in FIG. 2. In such a manner, a film layer with small apertures is formed on the substrate cloth 10 for increasing the gas permeability of the synthetic cloth, wherein the wetting ability of the synthetic cloth is about 1500 to 2000 g/SQMD. However, the P.U. surface layer 20 cannot be formed with proper patterns so as to fit the different requirements of the consumers, thereby limiting the versatility of the synthetic cloth.
A conventional wet type transfer coating method in accordance with the prior art shown in FIGS. 3 and 4 is used for manufacturing a synthetic cloth and comprises the following steps. First, a P.U. surface layer 20 is coated on a releasing sheet 1, and is then baked and dried. A bonding agent 30 is then bonded on the P.U. surface layer 20 for bonding a substrate cloth 10 to the P.U. surface layer 20. The substrate cloth 10 is a knitting cloth, a non-woven cloth, intersecting knitting cloth or the like. The bonding agent 30 is then baked and dried, and the releasing sheet 1 is then removed from the P.U. surface layer 20, thereby forming the final synthetic cloth which includes the P.U. surface layer 20, the bonding agent 30, and the substrate cloth 10 as shown in FIG. 4. A plurality of small apertures are formed in the P.U. surface layer 20 for increasing the gas permeability of the synthetic cloth, wherein the wetting ability of the synthetic cloth is decreased to about 650 g/SQMD. In such a manner, the patterns on the releasing sheet 1 is printed on the P.U. surface layer 20 by a transfer type. However, the wetting ability and gas permeability of the synthetic cloth are decreased.
In accordance with one aspect of the present invention, there is provided a method for manufacturing a polyurethane (P.U.) product with high wetting ability, gas permeability and high water repellent ability by means of a dry transfer coating process. The method comprises a front stage working, and a rear stage working.
The front stage working includes the steps of: providing a releasing sheet which has a plurality of pattern cavities defined therein; providing a first P.U. liquid which is scraping resistant and strong solvent resistant; coating the first P.U. liquid on the releasing sheet to fill the pattern cavities of the releasing sheet with the first P.U. liquid; baking and drying the first P.U. liquid to form a first P.U. surface layer on the releasing sheet; providing a second weak solvent P.U. liquid; coating the second weak solvent P.U. liquid on the first P.U. surface layer; baking and drying the second weak solvent P.U. liquid to form a second P.U. surface layer on the first P.U. surface layer; providing a bonding agent on the second P.U. surface layer; providing a substrate cloth on the bonding agent; and baking and drying the bonding agent so that the substrate cloth is securely bonded on the second P.U. surface layer through the bonding agent, thereby forming a first product which includes the first P.U. surface layer, the second P.U. surface layer, the bonding agent, and the substrate cloth.
The rear stage working includes the steps of: providing a first mixing liquid to be rolled and printed on the first product for performing a surface treatment of a first printing plate so as to form a plurality of intensive small air vents in the second P.U. surface layer for increasing permeability of the second P.U. surface layer; providing a second mixing liquid containing a fluoride to be rolled and printed on the first product for performing a surface treatment of a second printing plate so that the fluoride infiltrates through the first P.U. surface layer and the second P.U. surface layer for increasing a water repellent function of the first P.U. surface layer; and providing a third mixing liquid containing a P.U. solvent to be rolled and printed on the first product for performing a surface treatment of a third printing plate so as to increase comfort and quality of the first product, thereby making a final synthetic cloth product.
A primary, objective of the present invention is to provide a method which uses a transfer coating process to achieve a front stage working to form various patterns. The front stage working includes two coating steps, wherein the first coating step includes coating a scraping resistant and strong solvent resistant first P.U. liquid on the releasing sheet to form a first P.U. surface layer, and the second coating step includes coating a second weak solvent P.U. liquid on the first P.U. surface layer to form a second P.U. surface layer. The method also includes a rear stage working which uses a strong solvent made of D.M.F. to form a plurality of intensive small air vents in the second P.U. surface layer, wherein the transfer patterns printed by the first P.U. surface layer will not be broken.
Another objective of the present invention is to enhance the gas permeability and wetting ability of the synthetic cloth product by means of the intensive small air vents formed in the second P.U. surface layer.
A further objective of the present invention is to enhance the water repellent and waterproof effect of the synthetic cloth product by means of the fluoride.
A further objective of the present invention is to enhance the quality and comfort of the synthetic cloth product by means of the anti-blocking agent, the surfactant of wax type, and the surfactant of mat and bright.