Waterproof sheet

Abstract

To provide a waterproof sheet that can prolong the service life of products by reducing products to be discarded before deterioration of waterproof function due to sticking of pigments or browning.SOLUTION: Provided is a waterproof sheet for bed sheets and the like, which is obtained by laminating a surface cloth comprising a woven or knitted fabric and a waterproof film, wherein the surface cloth and the waterproof sheet are bonded directly or indirectly with an adhesive, and the waterproof film is a dark-colored film having a lightness of 4.5 or less in terms of 12 hues in PCCS (Practical Color Coordinate System). Also provided is a waterproof sheet which is obtained by laminating a surface cloth comprising a woven or knitted fabric, a waterproof film, and a back cloth comprising a woven or knitted fabric in this order, wherein the surface cloth, the waterproof sheet, and the back cloth are respectively bonded to each other directly or indirectly with an adhesive, and the waterproof film is a dark-colored film having a lightness of 4.5 or less in terms of 12 hues in PCCS.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a waterproof sheet used for various applications such as medical supplies, nursing care supplies, and sanitary supplies.

Background Art

[0002] Conventionally, waterproof sheets have been widely used in various fields. As a means for imparting a waterproof function to a sheet, for example, there is lamination of a waterproof film on a base sheet (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, particularly in bedding sheets, uniforms, and sanitary supplies such as sanitary products used in the medical and nursing care fields, stains such as body fluids such as sweat and blood, excrement, and food are difficult to remove even after washing. Therefore, in many cases, products are discarded due to the fixation of pigments caused by stains rather than a decrease in the waterproof function.

[0005] In addition, regarding waterproof sheets subjected to industrial washing, when treated with sodium hypochlorite, "brown discoloration" occurs, which is yellowing caused by the yellowing of the adhesive throughout the product, and this deterioration is also a cause of product disposal.

[0006] An object of the present invention is to provide a waterproof sheet that can reduce products discarded before the waterproof function deteriorates due to pigment fixation and brown discoloration and can extend the product life.

Means for Solving the Problems

[0007] The adhesion and browning of pigments in waterproof sheets are particularly noticeable in the adhesive layer, which, due to its properties, easily attracts dirt and other contaminants. It is difficult to remove pigments that have adhered to the adhesive, and it is difficult to significantly improve this condition. Therefore, after diligent research, the inventors of this invention have found a method to make the adhered pigments as inconspicuous as possible, rather than removing them, and have completed the present invention.

[0008] The present invention [1] A waterproof sheet for sheets, comprising a surface fabric made of woven or knitted material and a waterproof film laminated together, wherein the surface fabric and the waterproof film are directly or indirectly bonded together with an adhesive, and the waterproof film is a dark-colored film with a lightness of 4.5 or less in the 12-hue color system of the Japan Color Research Institute. [2] A waterproof sheet comprising a surface fabric made of woven or knitted fabric, a waterproof film, and a lining made of woven or knitted fabric, laminated in this order, wherein the surface fabric and the waterproof film and the waterproof film and the lining are bonded directly or indirectly by an adhesive, and the waterproof film is a dark-colored film with a lightness of 4.5 or less in the 12-hue color system of the Japan Color Research Institute, [3] The waterproof sheet described in [1] or [2] above, wherein the dark color of the film is black, dark gray, dark blue, dark brown, or ochre. [4] A waterproof sheet according to any of [1] to [3] above, wherein the outer fabric is a white or light-colored polyester woven or knitted fabric with a lightness of 7.5 or higher in the 12 hues of the Nippon Color Research Institute color scheme, and [5] A waterproof sheet used as a sheet, as described in any of [2] to [4] above. Regarding. [Effects of the Invention]

[0009] The waterproof sheet of the present invention has the excellent effect of reducing the number of products that are discarded before their waterproofing function deteriorates due to pigment adhesion or browning, thereby extending the lifespan of the product. Reducing the waste rate of waterproof sheets brings about a wide range of significant benefits, including a reduction in industrial waste and recyclable materials, and contributions to environmental protection through a decrease in the use of highly toxic chemicals such as sodium hypochlorite in industrial laundry and a reduction in wastewater. [Modes for carrying out the invention]

[0010] The waterproof sheet of the present invention is a multilayer sheet comprising layers in which a surface fabric made of at least a woven or knitted fabric and a waterproof film are bonded together with an adhesive, and a major feature of the present invention is that the waterproof film is a dark-colored film.

[0011] The outer fabric and waterproof film are laminated together with an adhesive, but the adhesive easily attracts dirt, and once pigments adhere to the adhesive, they are difficult to remove completely even with washing. As a result, pigments accumulate in the adhesive layer with use. Therefore, this invention focuses on the "principle of color." Typically, transparent or translucent adhesives are used, and they are greatly affected by the color of the waterproof film located behind the adhesive when viewed from the surface. With conventionally used white waterproof films, adhesive stains are affected by the white background film, making them stand out more strongly, and stains due to pigment deposition become noticeable. As a result, from the standpoint of appearance and hygiene, the waterproof sheet is discarded before its functionality deteriorates. However, in this invention, by using a dark-colored waterproof film, when viewed from the surface, the film absorbs light, making it difficult to perceive the change in the color of the adhesive. As a result, the pigment deposited in the adhesive is not noticeable on the surface, and the product can be used for a long period of time while its waterproof function is maintained.

[0012] Conventionally, various technologies have been considered to prevent dye transfer to adhesives. However, preventing dye transfer to adhesive components such as polyurethane adhesives is extremely difficult due to the properties of the adhesive components, and a satisfactory solution has yet to be found. In contrast, this invention solves the problems associated with dye contamination of waterproof sheets by taking a completely new approach that differs from conventional approaches that attempt to inhibit dye transfer to adhesives.

[0013] For example, a conventional approach involves dyeing the outer fabric to make stains less noticeable. While polyester is the mainstream material for commercial sheets used in industrial laundries, the disperse dyes commonly used to dye polyester materials lose strength when wet, and the dye may leach into the wash water. The leached dye can adhere to adhesives and linings, potentially causing contamination. Furthermore, the dyed outer fabric may change color due to the washing load, but in this invention, the possibility of contamination of the wash water is extremely low, and the initial change is minimal.

[0014] Furthermore, dark-colored waterproof films are easier to check for deterioration such as cracking compared to white films, allowing for early detection of a decline in waterproofing function.

[0015] In the present invention, a dark-colored film refers to a film with a lightness of 4.5 or less, preferably 2.5 or less, and more preferably 1.5 or less. The film's color is preferably black, dark gray, dark blue, dark brown, or ochre, with black being more preferred. In this specification, lightness is the lightness measured according to the 12-hue color system of the Japan Color Research Institute.

[0016] The waterproof film may be used on the back surface or as an intermediate layer of the waterproof sheet. Therefore, the waterproof sheet of the present invention is a waterproof sheet that includes a layer in which the surface fabric and the waterproof film are laminated with an adhesive in between. The first embodiment is a waterproof sheet having a laminated outer fabric made of woven or knitted material and a dark-colored waterproof film, wherein the outer fabric and the waterproof film are directly or indirectly bonded together with an adhesive, and the waterproof sheet has a two-layer structure with the outer fabric and waterproof film as the basic framework. The second embodiment is a waterproof sheet in which a woven or knitted outer fabric, a dark-colored waterproof film, and a woven or knitted lining are laminated in this order, and the outer fabric and the waterproof film, and the waterproof film and the lining, are bonded directly or indirectly by adhesive, resulting in a three-layer waterproof sheet with the outer fabric, waterproof film, and lining as the basic framework. That is the case. In this specification, the case of being "indirectly" adhered means being adhered through any material as long as the effects of the present invention are not impaired. As the material, coating resin or the like can be used, but it is not particularly limited.

[0017] In the case of a waterproof sheet having a three-layer structure in which a waterproof film is sandwiched between a front side and a back side, compared with a two-layer structure of only the front side and the waterproof film, the waterproof film is not exposed, so it has excellent durability.

[0018] The front side and the back side may be either a woven or knitted fabric, that is, either a knitted fabric or a woven fabric. However, from the viewpoint of following the stretchability of the polyurethane film, it is preferably a knitted fabric. When using a woven fabric, there may be a possibility of occurrence of curling, which is caused by the shrinkage difference between the front side and the film. The material is appropriately selected according to the application, and examples include polyester, polyester-cotton blended products, etc. In the present invention, as described above, a polyester woven or knitted fabric in which the effects of the present invention appear more prominently is preferable. Also, in terms of cleanliness in the medical and nursing care fields, since dark colors are not preferred for the color tones of the front side and the back side, white or light colors are preferred. Here, "light color" means white or those having a lightness of 7.5 or more, preferably 9.5 or more in the 12-color system of the Nippon Color Research配色体系.

[0019] The front side is preferably subjected to antifouling treatment. Examples of the antifouling treatment include treatment for imparting water absorption diffusibility using a water absorbent (soil release treatment), treatment using a water repellent and oil repellent (soil guard treatment), etc.

[0020] The thickness of the front side and the back side depends on the application, but is preferably 0.3 to 1.5 mm.

[0021] Examples of the material of the waterproof film include polyurethane, polyester, polypropylene, polyethylene, polyvinyl chloride, etc. Among these, polyurethane is preferable from the viewpoints of compatibility with adhesion to woven or knitted fabrics, processability, resistance to high-temperature washing treatment, and difficulty in feeling aversion to the film.

[0022] The thickness of the waterproof film is preferably 0.005 to 0.1 mm, although this depends on the application.

[0023] Examples of adhesives include polyurethane adhesives, acrylic adhesives, and silicone adhesives, but among these, the effects of the present invention are more pronounced when using a polyurethane adhesive, which tends to attract dirt.

[0024] The thickness of the adhesive layer is not particularly limited, as long as the adhesive is used to the extent that it can bond the outer fabric to the waterproof film and the lining to the waterproof film.

[0025] The method for manufacturing the waterproof sheet of the present invention is not particularly limited, and the waterproof sheet can be manufactured by bonding the surface fabric and the waterproof film, and the backing fabric and the waterproof film using an adhesive, and laminating techniques such as bonding or hot melt.

[0026] In the present invention, the two-layer waterproof sheet is used as a sheet for bedding used in the medical field, nursing care field, etc., while the three-layer waterproof sheet can be used not only as a sheet but also as uniform clothing, sanitary products, and other hygiene products. [Examples]

[0027] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples.

[0028] Example 1 A two-layer waterproof sheet was obtained by laminating a 0.03 mm thick black (brightness: 1.5) polyurethane film onto a 0.5 mm thick white (brightness: 9.5) polyester knitted fabric, which had been treated with a water-absorbing agent for stain resistance (soil release treatment), via a polyurethane adhesive.

[0029] Example 2 A two-layer waterproof sheet was obtained in the same manner as in Example 1, except that a white polyester knitted fabric that had not been treated with a water-absorbing agent for stain resistance was used.

[0030] Comparative Example 1 A waterproof sheet was obtained in the same manner as in Example 1, except that a white (brightness: 9.5) polyurethane film with a thickness of 0.03 mm was used instead of a black polyurethane film.

[0031] Comparative Example 2 A 0.5mm thick white (brightness: 9.5) polyester knitted fabric, which has not been treated with a water-absorbing agent for stain resistance (soil release treatment), was laminated with a 0.03mm thick white (brightness: 9.5) polyurethane film via a polyurethane adhesive. Furthermore, a 0.5mm thick white (brightness: 9.5) polyester knitted fabric, which has not been treated with a water-absorbing agent for stain resistance, was bonded to the back side (the side with the polyurethane film) using a polyurethane adhesive, resulting in a three-layer waterproof sheet.

[0032] Test Example 1 Demi-glace sauce was applied to the surface side of the waterproof sheets obtained in Examples 1 and 2, and Comparative Examples 1 and 2, in 9 locations (3 rows x 3 columns) with a diameter of 3 cm. After being left at room temperature for 1 day, the sheets underwent industrial washing treatment using sodium hypochlorite at Akane Clean, a cooperative of psychiatric hospitals in Kumamoto Prefecture.

[0033] The results of visual observation were as follows: Example 1: The stain cannot be identified. Example 2: A faint stain remains, but it is at a level that does not pose a practical problem. Comparative Example 1: A faint yellow stain remains. Comparative Example 2: Clearly, yellow stains remain.

[0034] Test Example 2 The waterproof sheets obtained in Example 1 and Comparative Example 2 were immersed in a chlorine-based bleach containing sodium hypochlorite for 30 minutes, then rinsed with 50°C water and ironed at a low temperature. After repeating this series of steps 50 times, the degree of browning of the adhesive was visually observed from the surface side. As a result, the waterproof sheet of Comparative Example 2 was clearly browned, while the waterproof sheet of Example 1 was slightly yellowed, but to a degree that did not pose any practical problems.

[0035] Example 3 A 0.5mm thick white (brightness: 9.5) polyester knitted fabric, treated with a water-absorbing agent for stain resistance, is laminated with a 0.03mm thick black polyurethane film via a polyurethane adhesive. Furthermore, a 0.5mm thick white (brightness: 9.5) polyester knitted fabric is bonded to the back side (the side with the polyurethane film) by applying a polyurethane adhesive, thereby obtaining a three-layer waterproof sheet.

[0036] Regarding the three-layer waterproof sheet of Example 3, it is clear that, similar to the two-layer waterproof sheet, it has the effect of making stains difficult to distinguish in Test Example 1, and also has the effect of suppressing browning in Test Example 2. [Industrial applicability]

[0037] The waterproof sheet of the present invention can be used for various purposes such as medical supplies, nursing care supplies, and hygiene products.

Claims

1. A waterproof sheet for use as a sheet, comprising a laminated surface fabric made of woven or knitted material and a waterproof film, wherein the surface fabric and the waterproof film are directly or indirectly bonded together with an adhesive, and the waterproof film is a dark-colored film with a lightness of 4.5 or less in the 12-hue color system of the Japan Color Research Institute.

2. A waterproof sheet comprising a surface fabric made of woven or knitted fabric, a waterproof film, and a lining made of woven or knitted fabric, laminated in this order, wherein the surface fabric and the waterproof film and the waterproof film and the lining are directly or indirectly bonded together by an adhesive, and the waterproof film is a dark-colored film with a lightness of 4.5 or less in the 12-hue color system of the Japan Color Research Institute.

3. The waterproof sheet according to claim 1 or 2, wherein the dark-colored film is black, dark gray, dark blue, dark brown, or ochre.

4. The waterproof sheet according to claim 1 or 2, wherein the outer fabric is a white or light-colored polyester woven or knitted fabric with a lightness of 7.5 or higher in the 12-hue color system of the Japan Color Research Institute.

5. A waterproof sheet according to claim 2, for use as a sheet.