JPH0749599B2 - Method for molding leather-like molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a leather-like molded product which is made into a fine powder of natural leather and then incorporated into a thermoplastic resin material to produce properties close to those of natural leather. Regarding the molding method, more specifically, in the powdering step of the natural leather, a steam heating step of the natural leather was added to cause a change in the protein composition due to heat swelling within a range in which the leather tissue, particularly protein collagen, does not melt. The present invention relates to a method for molding a leather-like molded product.

(Prior Art) Leather has been used for a long time since it has been closely attached to daily life. Due to the characteristic collagen fiber bundles of leather cloth, it has been used as a strong cloth material with moisture absorption, heat resistance, and cold resistance. It was

However, such a natural leather material has a limited supply, is vulnerable to swelling, and is liable to rot, mold, and discolor, and is always constrained in terms of shape.

Therefore, recently, synthetic leather or artificial leather having the original characteristics of leather has been improved, and polyamide-based, polyurethane-based, polyamino acid-based synthetic leather, or a three-dimensional fiber entangled body of special lotus root-type hollow fibers or fine fiber-focused fibers Artificial leather, which is composed of a binder and a porous structure of a polyurethane elastomer, has been supplied.

However, all of these are water-absorbing, passable or stretchable, all of which are intended to be created by reticulation and porosification by a synthetic resin material which is a non-swelling tissue. 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.

(Problems to be solved by the invention) As a method of utilizing the leather material as it is, the leather material is broken and beaten into a short fiber shape, and the short fiber material is pressed into a felt shape. Fastened felt materials, filter materials, and vibration material for speakers have been developed for a long time. However, the development of pulverizing or cutting a leather material into a powder, and making this powdery leather material into a leather material has been industrially promoted for the first time by the present applicant. Japanese Patent Application No. 61-102611, etc. Many inventions have been disclosed.

By the way, when such a leather material is powdered and mixed with a resin, the finer the leather powder, the better the characteristics of the leather-like material that has been formed, and the more easily it is compatible with the resin. There was 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, the leather material is 250
When made into a fine powder with a uniform mesh size, the fine powders are entangled with each other to give a cotton-like appearance, which does not mix properly with the synthetic resin material, and entangles with each other when molding the synthetic resin material. It was present as a lump, which was the cause of pulsation in the molding resin during extrusion molding and the like.

Further, when the leather material becomes 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 inferior. However, there is a problem that the molded product does not have the characteristics of the leather material mixed in at all.

(Specific Means for Solving Problems) A method for molding a leather-like molded article according to the present invention provides a more reliable method for crushing such conventional leather powder, and is relatively easy. In addition, it is for forming leather powder on a sufficient mass production scale and for forming leather-like molded products from the leather powder provided, cow leather, pig leather, which is usually provided as blue floor leather or shavings. Alternatively, sheep leather or the like is finely cut or crushed by using a cutting machine, and the cut or crushed leather material is steam-heated to change its protein composition and then dried so that the water content in the leather material is within 4%. . This dry leather material is made into a fine powder through a crusher such as a ball mill, and then screened with a 30-mesh sieve. The leather powder that passes through this sieve is used as one aggregate, and 15-60% of this leather powder is thermoplastic resin. A compound (85-40%) was kneaded in a weight ratio and extruded to form a leather-like molded product without resin molding such as a calendar roll.

(Function) The method for molding a leather-like molded article according to the present invention has the following functions in the molding of leather powder and in the molding of a leather-like molded article due to the above characteristic constitution.

(1) The formation of leather powder is premised on the steam heating step of cutting or crushing leather material, and the collagen protein constituting the leather is sufficiently swollen in this heating step, and its structural structure is changed with time. As a result of repeated changes in the solid-solution state due to heat changes, the close cohesion between tissues is relaxed, and the oils and fats 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.

When the leather material is dried to a water content of 2.3 to 3% in such a state, the cut or crushed leather material is crushed by a relatively small impact.

This dried cut or crushed leather material is gradually put into a ball mill etc., crushed, sorted with a 30 mesh sieve, and finer than 150 mesh 54.7% 100 to 150 mesh 18.4% 60 to 100 mesh 15.5% 30-60 mesh, 11.4% leather powder with a particle size distribution can be obtained.

(2) Further, even in the step of pulverizing the leather material into powder, the leather material is effectively made into a fine granular powder, and the crushed powder has a ciliated part, or the powder itself becomes fibrous. It is possible to form and provide a leather powder having good slipperiness without being worn.

(3) Further, the leather material, particularly viscoelasticity of collagen fibers and the loss of oil and fat, causes a systematic disintegration of the leather material, and the leather material can be efficiently granulated by a simple device. There is no sticking of the leather structure to the blade or the like, and no entanglement occurs.

(4) Further, the glue or oil and fat having weak tissue strength contained in the collagen fiber is removed, and a more pure leather powder having only the collagen protein part is obtained, and the particle size is uniform, and the cilia part is also present. It has a good compatibility with the plastic molding material to be kneaded because it does not have, and has the characteristic that it is mixed smoothly into the synthetic resin compound and mixes evenly. Never get entangled.

(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 is not dense and dense due to the pulsation generated at the time of molding. The amount is small and almost no distortion occurs during or after molding.

(6) Further, since the leather powder to be mixed is a purer collagen protein, it has a function of imparting a certain fluidity to the molded plastic material and further uniformizing the movement of the resin material itself. As a result, densification of the composition of the molded product is avoided more than in the usual plastic molding, and the mixed leather powder functions to individually cut off the residual stress generated in the molded resin material.

(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 swelling of the leather powder in the resin material is caused. There is no distortion of the molded product due to it, and there is no occurrence of warpage due to temperature change or humidity change of the molded product.

(Example) Hereinafter, an example of a method for molding a leather-like molded article according to the present invention will be described in detail.

Firstly, the leather used is mainly chrome tanned cowhide, pig skin, sheep skin, etc., 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 an advantage that they can be uniformly processed regardless of the type of beef hide or pig skin.

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 chrome treatment.

The leather material is subjected to a cutting machine or a crusher so as to be suitable for the following treatment, and then the leather material is put into a heating device and steam-heated for a predetermined time.

In this steam heating, it is ideal that the temperature inside the device is fluctuated within a certain range by further heating the leather material put 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 cylindrical wall of the cylindrical heating device, and sent steam of 130 ° C, 2 kg / cm ² into the space of this double wall to heat the device and While the same steam was supplied to the leather material, the leather material charged into the apparatus was stirred.

As a result, the leather material that has absorbed the water vapor supplied into the apparatus is heated from the cylindrical wall of the apparatus in a sufficiently swollen state, and its temperature rises while changing its properties in the direction of evaporation, and then the temperature of the leather material itself changes due to the vaporization phenomenon that occurs. When the temperature was lowered, the mixture was agitated and released into the air from the cylinder wall to rapidly lower the temperature, and at the same time re-swelled by the steam supplied into the apparatus.

In the above device, the leather material put into the steam heating device undergoes a change over time in a sufficiently swollen state, causing a change in the protein composition of the collagen protein and at the same time the oil and fat content and water solubility contained in the collagen fiber. The high glue portion was removed, resulting in a purer collagen protein, which was completely swollen for a long time.

Such swelling, drying the heated leather material, ideally,
It was rapidly dried to a water content of 2.3% to 4% (weight ratio) and put into a crusher. This crusher is an appropriate device such as a ball mill depending on the properties and shape of the leather material.Usually, a mill suitable for fine powder is used step by step in accordance with the crushed particle size to efficiently and efficiently. Moreover, leather powder having a uniform particle size could be obtained.

In particular, the leather material that has undergone the above pretreatment process is brittle against fracture, has no viscoelasticity, and is free from oils and fats, and can be crushed to an appropriate particle size within an extremely short time. Moreover, the crushed leather powder has a uniform particle size and has no cilia part.

By passing the crushed leather powder through a 30-mesh sieve, finer than 150 mesh 54.7% 100-150 mesh 18.4% 60-100 mesh 15.5% 30-60 mesh 11.4% ideal It was possible to obtain a leather powder having a different particle size distribution.

15-60% of leather powder molded by the above steps and 40-85% of thermoplastic resin compound such as vinyl chloride (both by weight) were mixed to form a plastic. At the time of this molding, a foamed molded article may be molded by separately mixing a filler such as calcium carbonate powder or gelatin or a modifier, and mixing a foaming agent.

When the purpose is to color the molded product or to obtain a colorless molded product, the leather powder itself to be mixed is subjected to decolorization treatment, and the coloring treatment and mixing of a coloring pigment during plastic molding are performed. Further, it is preferable to mainly color the leather material by a dyeing method, and one of the preferable dyeing methods is a heating step using the heating device in the above step and dyeing in the state of crushed leather before this heating step.

Incidentally, in the above plastic molding, a hard, semi-hard and soft plastic molded product is molded by appropriately mixing a modifier, an extender and the like according to the purpose.

Further, the molding means for plastic molding may be any of calender rolls, extrusion, injection and other methods, for example, to provide a sheet or film shaped molded article,
Further, the present invention is not limited to sheets and films, and handles and other molded products are provided.

Then, the surface of these sheets, films or various molded products may be subjected to a treatment such as sandblasting, sanding or surface slicing to remove the surface skin layer portion of the resin, thereby providing a suede-like product with a deep taste. It can be made to have a feel similar to that of genuine leather. In the case of a sheet or film molded product, a tearing strength can be increased by attaching a backing material of paper or cloth to this, and in particular sanding finishing can be facilitated.

Sheets, films and various molded products molded in this way are subjected to embossing with a texture roll or the like, or kneaded to give leather embossing, or brushed back skin, suede-like leather, and various It is possible to provide a leather-like molded article for various purposes by subjecting it to the same processing as general leather such as enamel leather coated with paint or matte leather.

(Effects of the invention) The present invention has a characteristic constitution as described above, whereby a plastic molded product containing leather powder can be easily molded, and in a state where leather powder is uniformly dispersed in the molded plastic molded product. It has the feature of being capable of plastic molding.

Claims (1)

[Claims] 1. A steam heating step for leather, a dry crushing step for steam-heated leather, and a plastic molding step in which crushed leather powder is mixed, wherein the water content during dry crushing is within 4% by weight. And, the pulverized powder has a particle size of 30 mesh sieve and the plastic molding is mixed with the thermoplastic resin compound 40 to 85% by weight to the leather powder 15 to 60%. Method for molding leather-like molded products.