JPS63152478A - Molding of leather-like article - Google Patents

Abstract

PURPOSE:To obtain a leather-like molded article close to natural leather characteristics, by heating leather powder in steam, drying the leather powder into a water content in a specific range, grinding into a specific fine particulate state, blending the fine powder with a thermoplastic resin containing gelatin and molding into a sheetlike state. CONSTITUTION:First a leather material is heated in steam, dried into <=4% water content in the leather and ground into a fine particulate state having particle diameters passing through 30 mesh sieve free from entanglement. 70-10wt% of the leather powder is blended with 30-90wt% thermoplastic resin compound (e.g. vinyl chloride, etc.) containing 5-30wt% gelatin (to promote fluidity) by weight ratio and molded into sheetlike or filmlike shape by calender rolls to give a leather-like molded article. Then the sheet is embossed, rubbed and embossed or napped so that a leather-like molded article matching any of various purposes can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention is a leather-like molded product in which natural leather is made into fine powder and then incorporated into thermoplastic resin fabric to produce characteristics similar to C natural leather. Regarding the molding method, more specifically, a natural leather steaming process is added to the natural leather pulverization process, and the protein composition is changed by heat swelling within a range where the leather tissue, especially protein collagen, does not melt. , relates to a method for molding leather-like molded products in which gelatin is mixed in during resin molding using these leather powders.

(Prior art) Leather has been used as a material closely related to daily life since ancient times, and due to the properties of the unique collagen fiber bundles of leather fabric, it has moisture absorption, heat resistance, and cold resistance properties, and can be used as a strong fabric material. Ta.

However, natural leather materials have a limited supply, are at risk of becoming brittle due to swelling, rotting, developing, and discoloring, and are always subject to constraints in terms of shape.

Therefore, in recent years, improvements have been made to synthetic leather or artificial leather that has the characteristics inherent to leather, such as polyamide-based, polyurethane-based, polyamino acid-based synthetic leather, or special lotus root type hollow H & fibers or three-dimensional fiber entanglement of fine fiber bundle type fibers. Artificial leathers and the like made of a porous structure of a binder mainly composed of a polyurethane elastomer and a polyurethane elastomer are now available.

However, all of these methods attempt to create water absorption, permeability, or elasticity through reticulation or porosity using synthetic resin materials that do not swell, and are different from natural leather based on biopolymers. It was considered difficult to develop similar properties.

From this point of view, the present applicant has made various improvements in order to make leather using collagen tissue itself, which is a biopolymer.

In particular, the present applicant intends to crush collagen fibers into powder and granules to eliminate the expansion and contraction of collagen fibers during drying and wetting, and to reconstitute a leather material with the collagen that constitutes collagen fibers, and by crushing the collagen fibers, Various improvements have been made to the molding method.

(Problem to be solved by the invention) As a method of using leather materials as they are, these leather materials are broken and beaten into short fibers, and these short fibers of leather material are pressed into a felt shape. Sitafelt materials, filter vortex materials, and vibrating fabric materials for speakers have been developed for some time. However, the present applicant was the first to proceed industrially with the development of pulverizing or cutting leather material into a powder form and using this powdered leather material to produce leather fabric, and patent application No. 102,813/1984, etc. Many inventions have been disclosed.

By the way, when a visible leather material is pulverized and mixed with resin and molded, it has been found that the finer the leather powder, the better the characteristics of the molded leather-like fabric, and the easier it is to blend with the resin. did.

However, when pulverizing leather material, it is technically difficult to make powder that is not fibrous and has a fine granule shape because the leather material is a raw material. When the particle size is larger than or smaller than the grain size, there is a problem in that the leather powder becomes entangled with each other in a cotton-like manner.

In particular, the leather material is crushed by a crusher or ultrafine crusher, etc.
When made into a uniform fine powder of about 0 mesh, the fine powder becomes intertwined with each other and takes on a cotton-like appearance, and does not mix properly with the synthetic resin material. It exists as a tangled mass, and this was considered to be the cause of pulsation in the molded resin during extrusion molding and the like.

In addition, if the leather material becomes a certain lump like this, a molded product will be obtained in which the resin material and the leather material are separated, and of course the strength of the molded product will be extremely poor. However, there was an inconvenience in that the molded product did not have any of the characteristics of the leather material to which it was mixed.

(Specific means for solving the problem) The method for forming a leather-like molded article according to the present invention provides a more reliable method of pulverizing leather powder than the conventional method, and can be achieved relatively easily. ,
Moreover, it provides molding of leather powder on a sufficient mass production scale and molds the molded leather powder and gelatin into leather-like molded products. Grass or sheepskin, etc. is cut or crushed into small pieces using a cutting machine, and the cut or crushed leather material is steamed in a steamer to change its protein composition, so that the moisture content in the leather strips is 4% or less. to dry. This dried leather material is passed through a grinder such as a ball mill or a colloid mill to form a fine powder, and then sorted through a 30-mesh sieve.The leather powder passing through this sieve is used as one of the aggregates. A thermoplastic resin compound containing gelatin equivalent to 5 to 30% in a weight ratio of 30 to 90% was kneaded and extruded, and the resin was molded into a calender roll or the like to form a leather-like molded product.

(Operations and Effects) The method for molding a leather-like molded product according to the present invention has the following features in molding leather powder and leather-like molded products, in addition to the above-mentioned features. To produce an action or effect (done).

(1) The shaping of leather powder is based on the cutting of leather or the steaming of crushed leather material, and the collagen protein that makes up the leather is sufficiently swollen in this steaming process, and its composition structure changes over time. As the changes occur, the state of coagulation and dissolution is repeated, and the tight unity between tissues is relaxed, and the fat and oil present between collagen fiber bundles is removed, resulting in a purer collagen protein aggregate. Furthermore, glue and other thick parts are eluted.

It has been found that when the leather material is dried under such conditions to a moisture content of 2.3 to 3%, the cut or crushed leather material is crushed with a relatively small impact.

Therefore, when this dried cut or crushed leather material was put into a ball mill, colloid mill, etc. in stages, crushed, and sorted through a 30-mesh sieve, the passing rate through a 150-mesh sieve was 54.7%, 100-1.
50 mesh tt 18, 4%60~100
mesh // 15, 5% 60 mesh
// 11 It was possible to obtain leather powder with a particle size distribution of 4%.

(2) Also, in the process of pulverizing leather material into powder, the leather material is effectively turned into fine granule-like powder, and cilia may remain in the pulverized powder, or the powder itself may become fibrous. A leather powder with good slipperiness was provided for molding.

(3) In addition, the leather tissue, especially the viscoelasticity of collagen fibers and the loss of oil and fat content, cause systematic disintegration of the leather material, and the pulverization of the leather material can be efficiently performed using a simple device.
This has the advantage that the leather tissue does not stick to or get entangled with the crushing blades, etc.

(4) In addition, the glue or oil content that has weak tissue strength contained in collagen fibers has been removed, resulting in a purer leather powder containing only the collagen protein part, and the particle size is uniform, and the cilia part is more pure. It is said to be compatible with the resin material being kneaded because it does not have any
Eliminates the inconvenience of mixed leather powder intertwining with each other during resin molding.

(5) In addition, since the leather powder mixed in resin molding does not have cilia, the contact resistance during molding such as extrusion and injection is low, and the composition of the molded product is less dense due to pulsation that occurs during molding. It has the advantage that almost no distortion occurs during or after molding.

(6) Furthermore, since the leather powder mixed in is a purer collagen protein, it has the ability to impart a certain fluidity to the molding resin and even out the movement of the resin fabric itself. , it has the property of being able to avoid densification of the molded product composition more than usual resin molding, and this mixed leather powder functions to individually cut off the residual stress that occurs in the molded resin fabric, resulting in It has become possible to provide molded products with less distortion.

(7) In particular, 5 to 30% in the resin compound to be molded.
% of gelatin, this gelatin forms a unique sol state when heated during resin molding.
It has been found that when dispersed in a resin compound, the fluidity of the molded resin is dramatically improved. As a result, the inhibition of fluidity that tends to occur when the leather powder is mixed in is avoided by the mixing of this gelatin, and it also has the function of adsorbing water vapor etc. into the formed dough. There is.

(8) In addition, the leather powder mixed into the resin compound has a uniform particle size and is evenly dispersed in the molded dough, resulting in the swelling of the leather powder in the resin dough. It has the advantage that there is no distortion of the molded product, and that warping of the molded product does not occur due to changes in temperature or humidity.

(8) Furthermore, the above-mentioned prevention of distortion can be achieved by
It is said to be more reliable by including 30% gelatin, and especially gelatin mixed in a high temperature molten state is evenly scattered throughout the molded product, and this gelatin portion is different depending on the situation. In addition, it was placed in the molded product in the form of a highly viscoelastic sol or gel.

As a result, the molding strain that occurs in the molding resin and the shrinkage strain caused by structural changes over time are absorbed or buffered in the mixed gelatin particles, thereby preventing overall distortion. .

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

The leather used is mainly chrome-treated cowhide, pigskin, sheepskin, etc., and some leather is tanned.

In the conventional method, the collagen fibers in cowhide were strong, so the crushing and pulverization process involved problems with uneven particle sizes and the generation of cilia. Although there has been a problem of poor grinding due to oil and fat content, the following examples have the advantage that they can be uniformly processed regardless of the type, whether it is cow skin or pig skin.

In addition, the use of toughened leather is to prevent the magnetization and decay of leather powder when it is incorporated into leather processing processes and molded products, and for this purpose, basically chromium Rubbed bedding or shaving waste is used.

In some cases, the floor skin or floor skin scraps used as back plowing material before chroming are used and the chromium treatment is applied to this.

After the leather material is passed through a cutting machine or a crusher to make it suitable for the following treatment, the leather material is placed in a steamer and heated with steam for a predetermined period of time.

Ideally, for this steam heating, the leather material placed in saturated steam is further heated from the outside while being stirred, so that the temperature inside the steaming device can be varied within the range of 90°C to 80°C. This ideal value is determined by the properties, shape, and amount of the leather to be input.

In one of the implementations, the applicant has constructed a cylindrical steaming device with double walls, and injects 130°Cl2k into the space of this double wall.
The leather material introduced into the apparatus was stirred while steam of g/crrr was sent to heat the apparatus and the same steam was supplied into the apparatus.

As a result, the leather material that has absorbed the water vapor supplied into the device is heated from the cylindrical wall of the device in a sufficiently swollen state, and increases in temperature while changing its properties in the transpiration direction.Then, due to the vaporization phenomenon that occurs, the leather material itself becomes heated. At the same time, the mixture was stirred and released from the cylinder wall into the air to rapidly lower its temperature, and at the same time it was re-swelled to a saturated state by the water vapor supplied into the apparatus.

In the above apparatus, the leather material input into the steamer undergoes thermal changes over time in a sufficiently swollen state, causing a change in the protein composition of collagen protein, as well as the oil and fat content contained in collagen fibers and water-soluble The high glue content was removed, resulting in a purer collagen protein that remained fully swollen for a longer period of time.

Ideally, dry the heated leather material until it swells.
It was rapidly dried to a moisture content of 2.3% to 4% (by weight) and then charged into a pulverizer. This pulverizer may be an appropriate device such as a ball mill or a colloid mill depending on the properties and shape of the leather material.Usually, mills suitable for pulverizing are used step by step according to the particle size of the pulverized material. Leather powder with uniform particle size could be obtained efficiently.

In particular, leather materials that have undergone the pretreatment process described above are fragile to breakage, have no viscoelasticity, and because oil and fat have been removed, it is possible to crush them to the appropriate particle size within an extremely short period of time. In addition, the crushed leather powder has a uniform particle size and has no cilia.

By passing the thus crushed leather powder through a 30-mesh sieve, the passing rate through a 150-mesh sieve is 54.7% 100~
150 mesh tt 18, 4%60~1
Leather powder having an ideal particle size distribution of 00 mesh tt 15, 5% 60 mesh//11.4% could be obtained.

10-70% of the leather powder molded through the above process is mixed with 30-90% (both by weight) of a thermoplastic resin compound such as vinyl chloride containing 5-30% gelatin to form a resin mold. However, during this molding, calcium carbonate powder, other aggregates or modifiers may be mixed separately, and a foaming molded product may be molded by mixing a foaming agent.

In addition, if the purpose is to color the molded product or to obtain a colorless molded product, the leather powder itself to be mixed must be decolorized, and the colored pigments must be mixed in during the coloring treatment and resin molding. . The coloring of leather materials mainly depends on the dyeing method, and it has been found that the most effective method is the steaming process using a steaming device as described above, and the dyeing of the crushed leather before this steaming process.

Note that the resin molded above is mixed with modifiers, extenders, etc. as appropriate for the purpose, and hard, semi-hard, and soft resin molded products were molded.

In addition, resin molding methods include calender rolls, extrusion, injection, and other methods.Although sheet or film-shaped molded products are mainly provided, they are not necessarily limited to sheets or films, and can also be used for handles, etc. It is also suitable for providing molded products.

The surface of these sheets, films, or various molded products may be subjected to treatments such as sandblasting, sanding, or surface slicing to remove the resin skin layer, resulting in a product with a deep suede-like appearance. Moreover, the feel was said to be close to that of genuine leather. In addition, in the case of a sheet or film molded product, a paper or cloth backing may be added to the product to increase its tear strength and make it particularly easy to sand.

The sheets, films, and various molded products formed in this way are subjected to embossing treatment using a grain roll, etc., or are rubbed to give leather grain, or are raised to produce buckskin or suede-like leather. It has become possible to provide leather-like molded products for various purposes by applying the same treatments as general leather, such as using paint to make enamel leather or matte leather.

(Issuance of procedural amendment) March 18, 1986

Claims (1)

[Scope of Claims] Consisting of a leather steaming process, a drying and crushing process of the steamed leather, and a resin molding process in which crushed leather powder is mixed, the water content during the drying and crushing is within 4% by weight, In addition, the crushed powder has a particle size that passes through a 30 mesh sieve, and the resin molding contains 70 to 70% of the leather powder to 30 to 90% of the thermoplastic resin compound containing gelatin equivalent to 5 to 30% by weight.
A method for molding a leather-like molded product, characterized in that the contamination rate is 10%.