JP2013255532A - Low heat-shrinkable cow leather - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low heat-shrinkable cow leather causing no wrinkle even in a heat test, and a method of manufacturing the hide.SOLUTION: As for a cow leather, the ratio of the thickness of a silver surface layer to the thickness of the cow leather is 55-85%, and the average of a shrinkage when being heated for 72 hours at 110°C is 3.0-3.7%.

Description

  The present invention relates to cowhide leather, and more particularly, to cowhide leather that has a silver surface layer having a predetermined thickness ratio and has low heat shrinkage and is suitable for an instrument panel of an automobile.

  An instrument panel (hereinafter referred to as “instrument panel”) is an automobile interior part provided with instruments such as a fuel gauge in front of a driver's seat of an automobile. An instrument panel for a high-grade automobile is mainly constituted by adhering a plurality of pieces of natural leather to a resin base material surface via a cushioning material. The leather for this use is required to have a small thermal shrinkage, unlike a case of covering a sewing product on a base material like a chair. This is to prevent the leather from shrinking and peeling from the substrate when exposed to direct sunlight. Furthermore, it is also necessary that the volatiles from the leather do not adhere to the windshield and cause fogging.

  In order to solve the above problems, the applicants previously heat-skin the leather at 100 ° C. to 110 ° C. for 1 to 3 hours, or 120 ° C. for 1 to 2 hours to heat-shrink the leather and remove volatiles. It was proposed to remove (Patent Document 1). However, the leather has a problem that wrinkles are generated in the curing (stationary) process after being bonded to the instrument panel substrate. In contrast, the present applicants have clarified that the wrinkles are caused by delamination (silver floating) between the silver surface layer and the network layer, and vacuum drying, pattern drying drying, and preheating are performed under predetermined conditions. This has led to suppression of wrinkles (Patent Document 2).

JP 2007-70487 A JP 2010-121012 A

  However, in the obtained leather, generation of wrinkles in the curing process was eliminated, but generation of wrinkles was observed in a more severe heat resistance test (110 ° C., 72 hours). Since the instrument panel is easily heated by direct sunlight, it is necessary that no soot is generated even in such a high temperature state. Therefore, an object of the present invention is to provide a low heat-shrinkable leather suitable for instrument panels that does not generate wrinkles even in a heat resistance test, and a method for producing the leather.

That is, the present invention is cowhide, the ratio of the thickness of the silver layer to the thickness of the cowhide is 55 to 85%, and the average value of the shrinkage when heated at 110 ° C. for 72 hours is 3. It is cow leather that is 0 to 3.7%.
Further, the present invention is a method for producing the above cowhide leather,
(I) The process of processing the raw material cowhide processed with the non-chrome glaze with the composition containing glaze, a greasing agent, and dye,
(II) including a drying step, and (III) a finishing step,
(II) The drying process
(1) The water content in cowhide is 2 to 2 based on the weight of the cowhide by the setter step, the vacuum drying step at 60 to 80 ° C. for 180 to 120 seconds following the setter step, and the pattern drying step following the vacuum drying step. 10% by weight, then
(2) A step of heating at 65 to 80 ° C. for 50 to 70 minutes,
Including
(III) Finishing process is a back-coating process in which a mesh layer of cowhide leather is spread and the ratio of the thickness of the silver surface layer to the thickness of the cowhide leather is 55 to 85%.
It is the method characterized by including.

  If the cowhide leather of the present invention is used, even if it is exposed to a high temperature in a state where it is affixed to the instrument panel substrate, it will not shrink and no wrinkles will be formed.

It is a cross-sectional photograph of an example of the cowhide leather of this invention. It is a figure which shows schematic structure of the instrument panel of this invention. It is a figure which shows the measuring method of the thermal contraction rate of the cowhide of this invention.

  The leather of the present invention is produced from cowhide. Various kinds of raw cowhide can be used, and the origin can be any country such as Japan, North America, Korea, etc., and any of cow hide, steer hide, or bull hide can be used. May be. In the present specification, a state in which nothing is added is referred to as “skin”, and a state in which some processing is applied is referred to as “leather”.

  The dermis after removing the epidermis from the raw skin is divided into two layers, the upper papillary layer and the lower reticulated layer, with the bottom of the hair root as a boundary. The surface of the nipple layer from which the epidermis has peeled is called a silver surface and consists of fine fibers. In the present invention, the silver layer refers to this silver surface and the nipple layer below it. The reticulated layer consists mainly of entangled collagen fibers. The ratio of the thickness of the silver layer in the raw leather to the total skin thickness is typically 20 to 44%, depending on the site.

  In the leather of the present invention, the raw leather is subjected to a predetermined treatment so that the ratio of the thickness of the silver layer to the total skin thickness is 55 to 85%. In FIG. 1, the cross-sectional photograph (x150) of an example of the leather of this invention is shown. In this photograph, A indicates the thickness of the silver layer and B indicates the thickness of the mesh layer. In this example, the ratio of the silver layer thickness to the total skin thickness is 57%. If the silver layer ratio is within the above range, no wrinkle is generated even when heated at a predetermined temperature. Preferably it is 58 to 82%. The thickness of the silver layer and the leather can be determined by observing the leather cross section with a stereomicroscope at a magnification of about 150 to 200 (150 to 200 times), measuring the thickness at multiple points, and averaging. it can.

  The leather has an average shrinkage of 3.0 to 3.7 when heated. Here, the average value of the shrinkage is drawn on the leather in a lattice-like figure with a side of about 10 cm along the parallel (X) and vertical (Y) directions of the cow's spine as shown in FIG. The reduction rate by heating (= 100−the length after heating / the initial length) (%) of the average value of the lengths of the respective lattices calculated according to the formula shown in FIG. In the figure, n is an integer of 2 or more, and is usually 3-5. Preferably, the average value is 3.1 to 3.6%.

  The presence or absence of wrinkles does not depend on the thickness of cowhide, but the thickness is usually 0.2 mm to 2 mm, preferably 0.5 to 0.8 mm, more preferably 0.6 to 0.7 mm. is there.

  The instrument panel has, for example, the form shown in FIG. In the figure, an instrument panel 1 has a structure in which a plurality of pieces of leather 3, 4, and 5 are bonded to a base material 2 via a cushion material layer (not shown). The portion to which the leather 4 is bonded is a portion in which the airbag is stored. The substrate is plastic or reinforced plastic, such as glass fiber reinforced PP, acrylonitrile / butadiene / styrene resin (ABS), acrylonitrile / ethylene-propylene-diene / styrene resin (AES), acrylonitrile / styrene resin (AS), polycarbonate ( PC) / ABS alloy, glass fiber reinforced PC / AES, etc. are used.

  As the cushion material, any material can be used as long as the object of the present invention is not hindered. For example, natural fibers such as cotton and wool, synthetic fibers such as polyethylene, polyamide and polyester, polypropylene, polyurethane and the like These foamed synthetic resins and combinations thereof can be used. Preferably, a cushion material in which synthetic fibers are raschel woven, for example, a cushion material in which polyester knit is raschel woven is used.

  Any adhesive can be used as long as the object of the present invention is not impaired. For example, an acrylic resin adhesive, a cyanoacrylate adhesive, a urethane resin adhesive, a cellulose adhesive, ethylene, and the like. -Vinyl acetate adhesives, epoxy resin adhesives, silicone adhesives, rubber adhesives, vinyl chloride adhesives, polyamide adhesives and the like. Preferably, a cyanoacrylate adhesive that cures with moisture in the air is used.

The cowhide of the present invention can be produced by the following method.
(I) The process of processing the raw material cowhide processed by the non-chrome glaze with the composition containing glaze, a greasing agent, and dye,
(II) including a drying step, and (III) a finishing step,
(II) The drying process
(1) The water content in the cowhide leather is set to 2 to 10% by weight with respect to the weight of the cowhide leather by the setter process, the vacuum drying process at 60 to 80 ° C. for 120 to 180 seconds, and the pattern drying process. Process, and
(2) A step of heating at 65 to 80 ° C. for 50 to 70 minutes,
Including
(III) A back-coating process in which the finishing process uses a mesh layer of cowhide leather, and the ratio of the thickness of the silver layer to the thickness of the cowhide leather is 55 to 85%.
The steps (I) and (II) are basically the same as the method described in Patent Document 2, and will be briefly described below.

  In the step (I), the raw cowhide treated with the non-chromium glaze is tanned, greased and dyed. As the raw cowhide leather treated with non-chromium glaze, wet white pre-glazed with glutaraldehyde, aluminum, synthetic tannin or the like is preferably used as a pre-treatment for non-chrome tanning. Examples of the glaze used for retanning include inorganic glazes such as aluminum and zirconium salts, vegetable tannins, condensates of amino compounds and formaldehyde, resin glazes such as polyacrylic acid, aldehydes, and the like. . Preferably, plant tannins are used.

  Examples of the greasing agent used include anionic greasing agents such as sulfated oil, cationic greasing agents such as amino compounds, amphoteric greasing agents such as alkyl betaines, and nonionic greasing agents such as fatty acid monoglycerides. Etc. Anionic greasing agents selected from sulfated oils, sulfonated oils, and sulfitized oils are preferably used from the viewpoint that fogging can be effectively prevented.

  As the dye, various dyes such as an acid dye, a direct dye, a basic dye, and a natural dye can be used depending on a desired color.

  In addition to glazes, greasing agents and dyes, the composition used in step (I) can broadly include those that can contribute to improving the commercial value of the product leather, for example, non-chrome glazes used The neutralizing agent for neutralizing may be contained.

  The composition comprises 1 to 1.3 times water, 2 to 5% greasing agent, 10 to 30% glaze, and the required amount of dye based on the weight of the raw leather. The treatment is usually performed at a temperature of about 40 to 60 ° C. for 10 to 12 hours in a rotating drum containing the raw material cowhide treated with the non-chrome glaze and the composition. After the treatment, the dye is fixed with formic acid or the like, and then the leather is thoroughly washed.

  (II) In the drying process, first, in the setter process, the moisture of the leather is squeezed using a roll setter or the like. As a result, the water content is usually about 50 to 60% by weight of the cow leather weight, and at the same time, the skin surface becomes flat.

  In the subsequent vacuum drying process, the cowhide leather is placed on a stainless steel plate heated to 60 to 80 ° C. so that the silver layer side of the cowhide leather is in contact with the stainless steel plate, and the cowhide leather is sandwiched between the stainless steel plates not heated from above. The space between both stainless plates is dried for 120 to 180 seconds under a vacuum of about 300 to 500 mmHg.

  Next, a pattern drying process of drying cowhide leather at 35 to 50 ° C. in a suspended state is performed so that the water content in the cowhide leather is 2 to 10% by weight of the cowhide weight. If the amount of water is less than the lower limit value, it becomes overdried, which is not preferable in terms of leather characteristics. On the other hand, if the upper limit is exceeded, wrinkles are likely to be generated by drying by heating.

  After the pattern drying step, it is conventional to perform taste removal, softening step (wet stretch), sealing treatment, buffing, softening step (vibration) and the like. And at the end of a drying process, cowhide is heated at 65-80 degreeC for 50-70 minutes. Thereby, the thermal contraction rate of the cowhide finally obtained can be lowered.

  (III) In the finishing step, first, a base coat layer is formed on the surface of the cowhide leather, then pigment coating is performed, and then the surface is coated with urethane paint or the like to improve the strength of the cowhide leather surface. Then, in the vibration process, the leather fibers are loosened. The method of the present invention is characterized in that, in the step of lining, the mesh layer is wound so that the ratio of the thickness of the silver layer to the thickness of the cowhide is 55 to 85%. When the ratio is within the above range, no wrinkle is generated even when subjected to a heating test, for example, at 110 ° C. for 72 hours. Before forming the base coat layer, apply a back paste such as acrylic resin on the back side of the cowhide leather to prevent the back fluff from adhering to the painted surface. Good.

<Example>
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.
[Preparation of leather]
Wet white (manufactured in Japan) 3.0 kg was used as the raw material cowhide and was processed in the following steps.
(I) Re-waxing / Greasing / Dyeing Treatment 3.0 kg of raw cowhide leather was treated in a drum at 35-50 ° C. for 10 hours in 0.5 kg of the composition (pH 3-4) shown in the table below.

After the completion of the process, the dye was fixed with formic acid and washed thoroughly with water.

(II) Drying process The moisture of the treated leather was squeezed by a setting machine, and the moisture was adjusted to about 60 to 70% by weight with respect to the leather weight. Next, in the vacuum drying step, leather was placed on the surface of a hot plate heated to 70 ° C., and the treatment was performed for 150 seconds while maintaining a vacuum (about 480 mmHg) with a vacuum pump while maintaining a state where no gas leaked. Next, pattern drying was performed (50 to 60 ° C.), and the water content was about 5% by weight based on the leather weight. After that, according to the standard method, taste removal (sprinkling on the surface), wet stretch (softening treatment using a pin plate), pre-base (sealing treatment before painting), buff (skin conditioning before painting), vibration (softening treatment) And heated at 70 ° C. for 1 hour.

(III) Finishing Step After forming a base coat layer on the surface of the dried leather, pigment coating was performed, and further, aqueous urethane coating was applied to the surface with a spray machine to cure the coating film. Subsequently, after loosening the leather fibers in the vibration process, the back side of the leather was shaved off in the backside process. The obtained leather was cut and the cross section was measured with a microscope (× 150) to obtain various thicknesses and silver layer ratios shown in Table 2.

[Preparation of test piece]
A type in which the obtained leather is cured by moisture in the air through a cushion material having a thickness of 5 mm, in which a polyester knit is raschel woven on the surface of a curved iron plate (curvature radius of about 30 cm) simulating an instrument panel The cyanoacrylate adhesive was used for adhesion. The reason why the curved iron plate is used is that wrinkles are more likely to occur than a flat plate, and it is conspicuous.

[Heating test]
Each leather test piece (cut into 10 cm in the spine parallel direction × 10 cm in the vertical direction) and the test piece prepared as described above were heated in a thermostatic bath at 110 ° C. The sample was taken out after 72 hours, and the dimensional change rate of the leather and the presence or absence of wrinkles in the leather on the test piece were visually confirmed and evaluated according to the following criteria.
A: No wrinkle B: There is a little wrinkle C: There are a lot of wrinkles The measurement method of the dimensional change rate was set to n = 3 according to the above-mentioned method. The results are shown in Table 2.

  As can be seen from Table 2, wrinkles occurred when the ratio of the silver layer to the cowhide thickness was outside the scope of the present invention. In contrast, the cowhide leather of the examples had no wrinkles and a dimensional change rate of 3.1 to 3.6%.

  The cowhide of the present invention is suitable as leather for automobile instrument panels.

1 Instrument panel 2 Base material 3, 4, 5 Leather piece

Claims (8)

It is cow leather, Comprising: Ratio of the thickness of the silver surface layer with respect to the thickness of this cow leather is 55-85%, and the average value of shrinkage | contraction rate when heated at 110 degreeC for 72 hours is 3.0-3.7% Is cowhide. The cowhide leather according to claim 1, wherein the thickness ratio of the silver layer is 58 to 82%. Cowhide leather according to claim 1 or 2, wherein an average value of the shrinkage rate is 3.1 to 3.6%. The cowhide according to any one of claims 1 to 3, wherein the thickness of the cowhide is 0.2 to 2 mm. The instrument panel for motor vehicles provided with the cowhide of any one of Claims 1-4 on the surface. The automotive instrument panel according to claim 5, wherein the cowhide is bonded to an automotive instrument panel substrate through a cushion material. The automotive instrument panel according to claim 6, wherein the cushion material is made of natural and / or synthetic fibers woven with Russell. A method for producing cowhide according to any one of claims 1 to 4,
(I) The process of processing the raw material cowhide processed with the non-chrome glaze with the composition containing glaze, a greasing agent, and dye,
(II) including a drying step, and (III) a finishing step,
(II) The drying process
(1) The water content in cowhide is 2 to 2 based on the weight of the cowhide by the setter step, the vacuum drying step at 60 to 80 ° C. for 180 to 120 seconds following the setter step, and the pattern drying step following the vacuum drying step. 10% by weight, then
(2) A step of heating at 65 to 80 ° C. for 50 to 70 minutes,
Including
(III) Finishing process is a back-coating process in which a mesh layer of cowhide leather is spread and the ratio of the thickness of the silver surface layer to the thickness of the cowhide leather is 55 to 85%.
A method comprising the steps of: