Stock material or miscellaneous articles – Layer or component removable to expose adhesive – Release layer
Reexamination Certificate
2001-11-01
2004-09-21
Singh, Arti R. (Department: 1771)
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
Release layer
C428S040100, C428S343000, C442S076000, C442S079000, C442S085000, C442S086000
Reexamination Certificate
active
06794003
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a moisture-permeable waterproof fabric with excellent moisture permeability and resistance to moisture condensation, and to a moisture-permeable resin film provided with a release sheet, which is used for production of the moisture-permeable waterproof fabric.
BACKGROUND ART
Moisture-permeable waterproof fabrics have traditionally been obtained by a publicly known process whereby a urethane resin film is formed on a release sheet, and is further coated with a urethane resin as an adhesive and dried, after which a woven fabric or knitted fabric is thermally compressed thereon to obtain a moisture-permeable waterproof fabric. Improvements have already been achieved in the performance of such moisture-permeable waterproof fabrics, but their object has been enhanced moisture permeability as measured by the calcium chloride method, along with improved water pressure resistance. Such improvements are aimed at obtaining more comfortable, reliable water-permeable waterproof fabrics. However, Sen'i Journal, Vol.41, No.11, pp.415-425 (1985) highlights the following problems connected with measurement by calcium chloride.
(1) An air layer is present at the end where the measuring target sample and vapor generating source are and vapor release diffusion occurs, constituting a barrier against movement of the vapor.
(2) The distance between the calcium chloride and the measuring target sample varies with time due to moisture absorption, so that the vapor permeation decreases as time passes.
(3) Because of the low volume of moisture absorbent, measurement values of highly moisture-permeable materials are similar, making it difficult to distinguish between such materials.
When evaluating moisture permeability in its connection with comfort it has been common to employ the method of JIS L-1099 A-1 (calcium chloride method) as mentioned above, but Hoechenstein Laboratories, Germany has established a comfort evaluation method using an artificial skin model, which has been registered as ISO11092.
The Sen'i Journal also teaches that a negative correlation exists between the moisture permeability resistance R
et
of the skin model and the moisture permeability in the potassium acetate method.
However, ISO11092 has been recognized as a more practical comfort evaluation method, and it is effective as a means of evaluating actual wearing comfort, similar to the JIS L-1099 potassium acetate method (B-1 method). On the other hand, there is absolutely no correlation between the moisture permeabilities in the calcium chloride method (A-1 method) and the potassium acetate method (B-1 method). The feature of measurement by the potassium acetate method is that the film is contacted directly with liquid water, and the rate of diffusion of water into the film or the rate of the process from dissolution to evaporation is measured. Thus, in order to achieve excellent measurement results by this measuring method it is necessary for the resin to be provided with a chemical structure or fine porous structure which allows easy movement of liquid moisture.
When the atmospheric temperature falls during actual wear, water droplets are formed and adhere to the inside of the clothing. In this condition moisture condensation, or formation and adhesion of water droplets occurs due to the difference in temperature between the outside air and the inside of the clothing, regardless of any considerable moisture permeability exhibited at a constant temperature (calcium chloride method), and this results in the problem of loss of body temperature.
For example, when the moisture condensation property is evaluated by a method in which a beaker containing hot water at 40° C. is placed over the urethane side of a measuring sample after which the cover is sealed and the amount of water adhering to the film side is measured after standing in an atmosphere of 10° C., 65% RH, moisture condensation can only be prevented by a performance whereby the adhered water droplets are rapidly absorbed and released out of the clothing material, and therefore the degree of moisture permeability in the potassium acetate method contributes substantially to the actual comfort in the clothing interior.
In practice, the effect of inhibiting moisture condensation is low even if the moisture permeability is high according to calcium chloride. The prior art has concentrated on improving the moisture permeability by calcium chloride while also improving the water pressure resistance, but has not attempted to improve the moisture permeability by the potassium acetate method which is more accurately related to comfort, and therefore the resulting moisture-permeable waterproof fabrics cannot necessarily be considered comfortable for actual use.
Urethane resins used to obtain moisture-permeable waterproof fabrics by lamination methods are hydrophilic ether-based polyurethane resins, and they are usually prepared as polyether-type urethanes by introduction of hydrophilic groups, such as a polyethylene glycol group or a pluoronic group which is a copolymer of ethylene glycol and propylene glycol.
In a conventionally employed method, a one-component type polyurethane resin film is formed as the surface coating on a release sheet, and then a two-component type adhesive comprising a hydrophilic polyether-based polyurethane resin is used for adhesion with the fabric. In this conventional method, however, the moisture permeability according to the B-1 method which correlates with actual comfort is not always high, being 5000 g/m
2
·24 hr or less, and it is not possible to achieve high moisture permeability of 15,000 g/m
2
·24 hr and greater. Also, because of the low absorption of liquid moisture, it is difficult to inhibit moisture condensation which occurs on the urethane film surface.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to overcome these problems by providing a moisture-permeable waterproof fabric with good comfort and highly reliable waterproofness, which produces no steaminess or moisture leakage even when employed under harsh conditions of wind and rain or intense exercise.
In order to achieve this object, the invention provides a moisture-permeable waterproof fabric comprising a textile fabric and a moisture-permeable resin film containing a non-porous urethane resin layer formed on at least one side thereof, wherein the moisture-permeable waterproof fabric has a moisture permeability of 15,000 g/m
2
·24 hr or greater according to the potassium acetate method, a moisture condensation of no more than 5 g/m
2
·hr and a water pressure resistance of 20,000 mmH
2
O or greater.
The invention further provides a release sheet-attached moisture-permeable waterproof resin film which comprises a release sheet and a moisture-permeable resin film formed thereon containing a non-porous urethane resin layer.
BEST MODE FOR CARRYING OUT THE INVENTION
As mentioned above, a conventional method for obtaining moisture-permeable waterproof fabrics is known whereby a surface layer comprising a hydrophilic polyurethane resin is formed on a release sheet, after which an adhesive comprising a hydrophilic polyurethane is coated and dried thereon for attachment to a textile fabric such as a woven fabric or knitted fabric, and improvements have also been proposed for enhanced moisture permeability and water pressure resistance of such moisture-permeable waterproof fabrics; however, there have been no proposed means for improving moisture permeability according to the potassium acetate method (B-1 method), which evaluates the actual wearing comfort. According to the prior art, the hydrophilic polyurethane resin film has a moisture swelling degree in the range of 10% at most. The moisture swelling degrees of adhesive films obtained by curing the adhesives with isocyanates are also in the range of 10% or lower. The moisture-permeable waterproof fabrics obtained by attaching these materials to textile fabrics have moisture permeability of at most 5000 g/m
2
·24 hr according to the A-1 method, a
Mukai Masashi
Nitta Kenji
Shimano Yasunao
Komatsu Seiren Co., Ltd.
Singh Arti R.
LandOfFree
Moisture-permeable waterproof fabric and release... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Moisture-permeable waterproof fabric and release..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Moisture-permeable waterproof fabric and release... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3205007