JPH08260000A - Leatherlike foamed sheet - Google Patents

Abstract

PURPOSE: To obtain a leatherlike foamed sheet which has a feel to the touch similar to a natural leather and does not exhibit the distortion due to swelling of a leather powder contained therein nor the warpage accompanying to change in temp. or humidity by molding a mixture comprising a specific leather powder and a thermoplastic resin compsn. CONSTITUTION: This molding is obtd. from a mixture comprising a fine leather powder contg. no cilia part and a thermoplastic resin compsn. (e.g. PVC), if necessary by foaming the mixture with a blowing agent. The leather powder is obtd. e.g. by subjecting split leather or shaving scraps of chrome-tanned cow leather, pig leather, sheep leather, etc., to steam heating to thermally swell them without melting leather texture, esp. protein collagen, to thereby change the protein compsn. and simultaneously remove the oil and fat component and glue component contained in the collagen fibers, then drying the resulting product, and grinding it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leather-like molded article obtained by incorporating natural leather into a finely powdered state and incorporating it into a thermoplastic resin material to produce properties close to those of a natural leather.
More specifically, in the powdering process of natural leather, a steam heating process of natural leather is added to use a leather powder that causes a change in protein composition due to heat swelling within a range in which leather tissue, particularly protein collagen does not melt. And also relates to a foamed leather-like sheet-like molded article.

[0002]

2. Description of the Related Art Leather has been used for a long time since it has been in close contact with daily life. Due to the characteristic collagen fiber bundles of leather fabric, it has moisture absorption, heat resistance, and cold resistance as well as its use as a tough fabric material. Was there. However, such a natural leather material has a limited supply, is vulnerable to swelling, and is liable to decay, mold, and discoloration, and the shape is always restricted.

Therefore, recently, synthetic leather or artificial leather having the original characteristics of leather has been improved, and three-dimensionally made of polyamide type, polyurethane type, polyamino acid type synthetic leather, or special lotus root type hollow fiber or fine fiber bundle type fiber. Artificial leathers and the like, which are composed of a fiber entangled body and a porous structure of a binder mainly composed of polyurethane elastomer, have been supplied. However, all of these are water-absorbing, breathable or stretchable, and are intended to be made by reticulation and porosification by a synthetic resin material which is a non-swelling tissue, and natural leather based on biopolymer It has been difficult to express similar properties.
From this point of view, the present applicant has made various improvements to make leather by utilizing the collagen tissue itself which is a biopolymer. In particular, the present applicant intends to crush the collagen fibers, as a powdery granule, to eliminate the expansion and contraction of the collagen fibers when dry and wet, and to reconstruct the leather material with the collagen that constitutes the collagen fibers, and the crushing thereof. Various improvements have been made to the molding method.

[0004]

As a method for utilizing the leather material as it is, the leather material is cut into short fibers while being smashed and tapped, and the short fiber materials are pressed into a felt shape. Felt materials, filter vortex materials, and vibration material materials for speakers have been developed for some time. However, the development of pulverizing or cutting a leather material into a powder form and making the powdery leather material into a leather material has been industrially promoted for the first time by the present applicant. Japanese Patent Application No. 61-10
Many inventions such as No. 2611 are disclosed.

By the way, when such a leather material is granulated and mixed with a resin, the finer the leather powder, the better the characteristics of the formed leather-like material, and the more easily it is compatible with the resin. It has been found. However, when the leather material is granulated, it is technically difficult to make a fine granular non-fibrous powder because the leather material is collagenous. When the particle size is above or below the particle size, there is a disadvantage that the leather powders are entangled in a cotton shape. Especially when the leather material is made into a uniform fine powder of about 250 mesh with a crusher or an ultrafine crusher, the fine powders become entangled with each other to give a cotton-like shape, which does not mix properly with the synthetic resin material. During molding with a resin material, they existed as entangled lumps in a resin molded product, which was considered to cause pulsation in the molded resin during extrusion molding and the like.

When the leather material is formed into a certain mass in this way, a molded product in which the resin material and the leather material are separated from each other is obtained, and the strength of the molded product is extremely poor. As a matter of course, there is a disadvantage that the molded article does not have the features of the leather material to be mixed.

The leather-like sheet-like foamed molded article according to the present invention eliminates the disadvantages of the leather-like molded article provided by the above-mentioned constitution and molding method, and has the leather-like sheet-like foamed article having sufficient characteristics of the leather material. The purpose is to provide molded products.

[0008]

MEANS FOR SOLVING THE PROBLEMS A leather-like sheet according to the present invention (also referred to as a film in the present invention is generally expressed as a sheet, and does not mean that the film is excluded). In order to achieve the above object, is configured as a leather-like sheet-like foam-molded article obtained by mixing finely powdered leather powder having no cilia part in a thermoplastic resin compound.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A leather-like sheet-like foam molded article according to a typical embodiment of the present invention will be described in detail below.

The leather-like sheet-like foam-molded article according to this embodiment is a leather-like sheet-like foam-molded article formed by fine-powdered leather powder having no cilia part, a thermoplastic resin compound and a foaming agent. It is configured as an item.

First, the leather powder used is mainly chrome tanned cowhide, pig skin, sheep skin or the like, and tannin tanned leather is used in part. Since the collagen fiber of the cowhide in the conventional method was tough, its crushing, in the process of pulverizing, the problem of uneven particle size, and the problem of cilia generation, and also in pig skin, in the leather Although there was a problem of crushing failure due to fats and oils, the following examples have the advantage that they can be uniformly treated regardless of the type, whether it is cowhide or pigskin. In addition, the use of tanned leather is to treat the leather processing and to prevent the development and decay of leather powder in the state of being incorporated in the molded product, and basically from that purpose, chrome tanning is used. Treated floor skin or shavings are utilized. In addition, there is also a case where a floor skin or floor skin waste as a back lining material before chrome tanning is used and this is subjected to a chrome treatment.

[0012] After such a leather material is cut into pieces or powder or fluffy so as to be suitable for the following treatment by a cutting machine or a crusher, the treated leather is put into a steam heating device and steam-heated for a predetermined time. Give. In this steam heating, it is ideal that the temperature inside the heating device is fluctuated within a certain range by further heating the leather thrown into the steam from the outside while stirring. The ideal value is determined by the nature, shape and quantity. In carrying out one of them, the applicant doubled the tubular wall of the tubular heating device, and sent steam at 130 ° C. and 2 kg / cm ² into the space of the double wall to heat the device and With the same steam being supplied to the inside, the leather put into the apparatus was stirred. As a result, the leather that has absorbed the water vapor supplied to the device is heated from the tubular wall of the device in a sufficiently swollen state, and the temperature rises while changing its properties in the direction of evaporation, and then the temperature of the leather itself is lowered by the vaporization phenomenon that occurs. At the same time, it was agitated and discharged from the cylinder wall into the air to rapidly lower the temperature, and at the same time, it was re-swelled to a saturated state by the steam supplied into the apparatus. In the above device, the leather put into the heating device undergoes a thermal change over time in a sufficiently swollen state, which causes a change in the protein composition of the collagen protein and the oil and fat content and the water-soluble content contained in the collagen fiber. The high glue portion was removed, resulting in a purer collagen protein, which was in a completely swollen state for a long time.

The swelled and heated leather was dried, and ideally rapidly dried to a water content of 2.3% to 4% (weight ratio) and put into a grinder. This crusher may be an appropriate device such as a ball mill depending on the properties and shape of the leather, and it is usually efficient by using a mill suitable for finely powdered one by one according to the crushed particle size, step by step. It was possible to obtain a leather powder with a uniform particle size. In particular, the leather that has undergone the above pretreatment step is fragile against breakage, has no viscoelasticity, and can be pulverized to an appropriate particle size within an extremely short time because the oil and fat components have been removed, Moreover, the crushed leather powder has a uniform particle size and has no cilia part.

The thus crushed leather powder is passed through a 30-mesh sieve to make it finer than 150 mesh 54.7% 100-150 mesh 18.4% 60-100 mesh 15.5% 30-60 mesh 11.4% It was possible to obtain a leather powder having an ideal particle size distribution.

Leather powder 15 formed by the above steps
-60%, a resin compound consisting of a thermoplastic resin such as vinyl chloride and a plasticizer, a stabilizer, etc. in a proportion of 40 to 85% (both by weight), and mixed with ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, and peroxide. Plastic molding is performed by adding a foaming agent containing oxides and azides, and in this molding, a sheet-shaped foam molded article is molded by mixing a filler such as calcium carbonate powder or a modifier separately. .

When the purpose is to color the molded product or to obtain a colorless molded product, the decoloring treatment of the leather powder itself to be mixed, the coloring treatment and the molding of the sheet-like foam molded product are performed. Mixing with coloring pigments. Also,
The coloring of the leather material is mainly based on the dyeing method, and the heating step by the steam heating device in the above step,
Dyeing in the state of crushed leather before this heating step was the most effective.

The resin compound molded in the above is a plasticizer in an amount suitable for the type of resin used,
By mixing a stabilizer, a filler and the like, it is possible to mold a rigid, semi-rigid and soft plastic sheet-like foam molded article. Further, as the plastic molding means, calender rolls, extrusion, and other methods can be used, and a foamed molded product mainly in the form of a sheet or film is provided.

The surface of the sheet or film may be subjected to a treatment such as sandblasting, sanding or surface slicing to remove the skin layer portion on the surface of the molded product, whereby a product with a deep suede tone is obtained. In addition, the texture should be close to that of genuine leather. Further, the sheet or film may be provided with a paper or cloth backing material to increase the tear strength, and particularly to facilitate sanding finish.

The sheet or film formed in this manner is subjected to embossing treatment with a texture roll or the like, or is kneaded to give a leather grain, or a brushed back skin or a suede-like leather, and various paints. The leather can be subjected to the same processing as ordinary leather such as enamel leather or matte leather using the above, and thereby a leather-like sheet-like foamed molded article can be provided for various purposes.

The leather-like sheet-like foam-molded article having the above-mentioned constitution has the following characteristic features in the molding of the leather powder to be mixed and the formation of the leather-like sheet-like foam-molded article. It produces a characteristic action such as.

(1) The leather powder to be molded is premised on the steam heating step of the leather, and in this heating step, the collagen protein constituting the leather is sufficiently swollen, and its composition structure undergoes a thermal change with time. Accompanying this, the solid-solid state is repeatedly repeated, the close cohesion between tissues is relaxed, and the fats and oils existing between collagen fiber bundles are removed, resulting in a more pure collagen protein aggregate. In addition, some glue and other glue parts are eluted. 2.3 to 3 in such a state
It has been found that when the leather is dried to a moisture content of wt%, the leather is crushed with a relatively small impact. Therefore, when this dried steamed leather was gradually put into a ball mill or the like, crushed, and screened with a 30-mesh sieve, it was finer than 150 mesh 54.7% 100-150 mesh 18.4% 60-100 mesh 15.5 It was possible to obtain a leather powder having a particle size distribution of 11.4% with a mesh percentage of 30 to 60 mesh.

(2) Further, even in the step of pulverizing the leather into powder, the leather is effectively made into a fine granular powder, and the pulverized powder has a ciliated part or the powder itself is fibrous. As a result, a leather powder having good slipperiness was formed and provided.

(3) Further, the viscoelasticity of the leather tissue, in particular the collagen fiber and the loss of oil and fat cause a systematic disintegration of the leather, which makes it possible to efficiently granulate the leather with a simple device. It has the feature that the leather tissue does not become loose and entangled with the crushing blade.

(4) Further, the glue or oil and fat having a weak tissue strength contained in the collagen fiber is removed to obtain a purer leather powder having only a collagen protein portion and a uniform particle size, Moreover, since it does not have cilia, it is said that it has good compatibility with the synthetic resin material to be kneaded,
It has the characteristic that it is smoothly mixed into the synthetic resin material and mixed evenly, and there is no inconvenience that the mixed leather powders become entangled during plastic molding.

(5) Further, since the leather powder mixed in the plastic molding does not have a cilia part, the contact resistance at the time of molding such as extrusion and injection is low, and the composition of the molded product due to the pulsation generated at the time of molding The feature is that there is little densification and there is almost no distortion during or after molding.

(6) Further, since the leather powder to be mixed in is a purer collagen protein, it has a function of imparting a certain fluidity to the molding resin material and uniformizing the movement of the molding resin material itself. As a result, it has the property of avoiding densification of the composition of the molded product more than usual resin molding, and also functions to individually cut off the residual stress generated in the molded resin cloth by the leather powder mixed in. As a result, it is possible to provide a molded product with less distortion.

(7) Further, the leather powder mixed in the synthetic resin compound has a uniform particle size, and as a result of being evenly distributed in the molding material, the leather in the molding resin material There is an advantage that the molded product does not warp due to the swelling of the powder and that the molded product does not warp due to temperature change and humidity change.

(8) Further, when a foaming agent such as ammonium carbonate is added to the molding material to form a closed-cell or open-cell or a sheet-shaped molded article having a foaming mode in which these are mixed,
The properties of the leather powder constituting the sheet-shaped molded product and the foamed structure are combined to provide the characteristics and feel that are closer to those of a natural leather material. In particular, since the sheet-shaped molded product is in a foamed state, the leather powder mixed in each foaming surface is exposed, and due to these swelling functions, it is made into a sheet-shaped molded product having a moisture content close to that of natural leather, and also an appropriate amount. It has the functions of almost the same as natural leather, since it has the functions of absorbing and evaporating water, as well as ventilation and moisture permeability.

(9) Such natural leather-like characteristics are more remarkably produced by removing the surface of the foamed sheet-shaped molded product by sanding, shot blasting or slicing. By cutting off the skin layer portion on the surface of the molded product, the foamed void surface is exposed to the outer surface and the leather powder is directly exposed to the surface of the sheet-shaped molded product without being covered with the resin skin layer.
As a result, the leather powder part absorbs perspiration on the contact surface and creates a lot of air pockets on the contact surface. Is a leather-like sheet-like molded article that provides a cool feel.

[0030]

INDUSTRIAL APPLICABILITY According to the present invention, finely powdered leather powder having no cilia part is mixed with a thermoplastic resin compound to form a leather-like sheet-like foamed molded product, so that the leather powder is uniformly distributed in the molded product. In addition, it is possible to provide a molded product that is evenly dispersed, does not warp due to swelling of leather powder, and does not warp due to temperature change and humidity change. It has the feature that it can provide a molded product with characteristics similar to that of leather and a feeling of touch.

Claims (1)

[Claims] 1. A leather-like sheet-like foam-molded article, characterized in that a fine-powdered leather powder having no cilia part is mixed in a thermoplastic resin compound.