JPH0791788B2 - Leather-like molded product - Google Patents

Description

TECHNICAL FIELD The present invention relates to a leather-like molding composition, in particular, a leather-like molding using ultrafine leather powder containing few impurities, and is used for home appliances, vehicle parts, stationery, furniture. It can be used for musical instruments.

[Background technology]

A technique in which leather powder made from animal leather is mixed with synthetic resin or rubber and pelletized for molding (JP-A-63
-152698) or a technique of integrating or molding (for example, JP-A Nos. 53-12902 and 63-11311).

[Problems to be Solved by the Invention]

However, the leather-like molded articles obtained by these techniques have a drawback that white powder is generated on the surface thereof, particularly when left for a long time in a humid atmosphere, and the performance and quality (appearance) of the product are deteriorated.

An object of the present invention is to provide a leather-like molded article having excellent long-term performance and quality without generation of white powder.

[Means and Actions for Solving the Problems]

The present invention aims to achieve the above-mentioned object by focusing on the fact that in the production of a leather-like molded product, ultrafine leather powder having a specific particle size with few impurities can prevent the generation of white powder.

The leather-like molded article of the present invention has a cortical content of 85 wt% or more, an oil and fat content of 2 wt% or less, a total amount of water-extractable Na ⁺ ions and Ca ²⁺ ions of 0.5 wt% or less, and an average particle size. Leather powder 1 having a D ₅₀ of 7 μm or less and a standard deviation of the particle size of 3 μm or less
~ 90wt% and at least one of the group consisting of synthetic resin and rubber
It is mainly composed of a dispersion mixture of 99 to 10 wt% of seeds.

The leather-like molded article of the present invention is basically a synthetic resin and / or rubber 2 with leather powder 1 dispersed in a sea-island shape, as shown in FIG.

In this type of molded article, the amount of the leather powder material and at least one material selected from the group consisting of synthetic resins and rubbers, respectively, is 1 based on the mixture of these two materials.
Is in the range of ~ 90 wt% and 99-10 wt%. If the proportion of leather powder exceeds 90 wt%, embrittlement will appear in the molded product, and 1 wt%
If it is less than the above, the effect is not obtained.

In the molded article of the present invention, the characteristic value of the leather powder is limited for the following reason.

1) Cortical content 85 wt% or more: A high content of cortical content means that the amount of impurities is small, and at the same time, it is important to improve the surface condition and touch feeling of products mixed with leather and paint. It means to be a factor. That is, the surface state and the like of the product can be efficiently improved with a small amount of powder having a large cortical content.

2) Oil and fat content 2 wt% or less (preferably 0.5 wt% or less): The oil and fat content present in animal leather is deteriorated by heat etc., and the surface texture is deteriorated due to malodor, coloring and bleeding out of the mixed product (greasy, slimy, It causes a feeling of shiny). Therefore, the lower the oil and fat content, the better.

3) Total amount of free ions (Na ⁺ , Ca ²⁺ ) that can be extracted with water.
5 wt% or less: Of the impurities derived from leather raw materials, if the amount of free ions extracted with water is large, it will be affected by humidity, heat, etc. when commercialized, and its salts (eg NaCl, Na ₂ SO ₄ , CaSO ₄
Bleed out, which leads to deterioration of the product appearance.
As free ions that can be extracted with water, in addition to the cations of Na ⁺ and Ca ²⁺ , there are anions of Cl ^- and SO ₄ ^2- , but those that bleed out are those ions. Since it occurs only in the form of the counterion salt, it was defined as the total amount of the small cations Na ⁺ and Ca ²⁺ .

4) Average particle size D ₅₀ ≦ 7 μm and standard deviation σ ≦ 3 μm: The particle size is a decisive factor for thin-walled products, and if the particle size is large, defects due to poor dispersion and deterioration of surface texture (roughness, Unevenness). On the other hand, the smaller the particle size, the better the dispersion and the fewer product defects (void, yarn breakage, etc.)
A product having a surface state with a good touch feeling can be obtained. Also, a small standard deviation means that there is little inclusion of large particles in distribution.

The method for measuring the above characteristic values is as follows.

A) Cortical content and oil content: According to JIS K6550-1976 "Leather test method" 6.7 and 6.4.

B) Total amount of free ions (Na ⁺ , Ca ²⁺ ) extractable with water: 10 g of dried leather powder is stirred in 100 ml of pure water for 24 hours to extract the free ions in the leather powder. The amount of Na ⁺ and Ca ²⁺ in the extract is quantified by atomic absorption spectrometry and calculated as the amount extracted from leather powder.

C) Distribution of average particle size and standard deviation: Coulter counter (manufactured by Coulter Electronics Co.) by dispersing dozens of mg of leather powder in 100 ml of methanol
The distribution of particles is measured by and the average particle diameter and standard deviation are obtained.

The density range of the leather powder is usually 0.38 to 0.43 g / cc (measured according to JIS K6721 after drying the leather powder at 120 ° C for 2 hours). If the density is too high, the particle size increases and exceeds the prescribed average particle size of 7 μm. On the other hand, if the density is too low, the leather powder becomes fibrous, and many hairs appear and are uniform with the synthetic resin. It may be difficult to disperse in.

The leather powder used in the present invention as described above is, for example, coarsely pulverized with respect to the leather powder raw material, dried, degreased with a solvent, residual solvent removed, washed with water, dehydrated, swelling treatment with steam, dried,
After performing each step of fine pulverization and classification of fine powder and coarse powder,
Further, it can be produced by carrying out a step of re-pulverizing the fine powder to an average particle diameter D ₅₀ = 7 μm or less. After this,
It is also possible to classify and remove the fine powder having D ₅₀ = 2 μm or less from the fine powder having D ₅₀ = 7 μm or less to make the particle diameter uniform.

This manufacturing method will be described in more detail. First, in order to facilitate the fine powder frame in the subsequent step, the leather powder raw material is roughly crushed to a particle size of about 10 mm or less by a crusher such as a jaw crusher, a cutter mill, or a hammer crusher. The coarsely crushed leather powder thus obtained usually contains 40 to 60 wt% of water. As the raw material for the leather powder, shaving waste leather, floor leather and the like can be used.

Next, in order to facilitate the degreasing (removal of oils and fats) in the subsequent process, the water-containing coarse powder is added until the water content becomes about 20 to 30 wt%.
dry.

Next, this dry crude powder was mixed with a suitable solvent to obtain a fat and oil content of 2 wt.
%, Preferably less than 0.5 w%. Here, as the degreasing solvent, n-hexane, benzine, methylene chloride, acetone, ethyl acetate, toluene and the like can be used.

Subsequently, in order to remove the residual solvent in the coarse powder, the coarse powder after degreasing is heat-treated. Since steam is usually used as a heat source for safety reasons, this process is also called steam purge. As other heat source, heated nitrogen, heated air, etc. can be used.

Next, extract mainly free ions (Na ⁺ , Ca ²⁺ ) in leather,
A water washing process and a dehydration process are performed in order to retain the predetermined water content in the coarse powder while removing it. It is effective to repeat this series of water washing operations several times in a batch system.For example, a certain amount of water is supplied to the crude powder after solvent removal, and after stirring for a desired time and bubbling with air if necessary, dehydration is performed. The method is usually repeated several times, preferably 3 to 4 times, depending on the amount of water supplied. Dehydration is usually performed by filtration (draining or draining) from the viewpoint of easy operation, but it may be performed by another method such as centrifugal dehydration. It should be noted that the continuous washing operation uses a large amount of water and is not advantageous, but it is possible.

The water temperature may be room temperature, preferably 30 ° C or lower.

Free Na ⁺ ions and C
A water-containing coarse powder having a total amount of 0.5% by weight or less of a2 ⁺ ions (converted to dry weight) and a water content of 65 to 70% is usually obtained. This series of water washing operations will eventually cause the coarse powder to normally retain a certain amount of water (65-70%), so this method is conventionally performed only by confirming the water content of the coarse powder after dehydration. As described above, there is an advantage that the humidity control step of replenishing water until the coarse powder after removing the solvent has a predetermined water content can be virtually eliminated.

Here, the reason why the predetermined amount of water is retained or supplied to the coarse powder is as follows. That is, in the dry state, even if finely pulverized after steam steaming in the next step, pulverization does not proceed.
However, when steam-steamed coarse powder containing water and thus swollen, it is partially heat-denatured, and when it is dried, it becomes tight and hard, and is easily ground and pulverized.

Next, in order to facilitate the fine pulverization in the subsequent step, the coarsely crushed leather powder after dehydration is subjected to a swelling treatment (steam steaming) with steam while stirring.

Subsequently, in order to facilitate the fine pulverization in the subsequent step, the coarsely crushed leather powder after the swelling treatment is dried until the water content becomes about 3 wt% or less. This drying step is usually performed by combining preliminary drying with a dryer and main drying with a vacuum dryer.

Next, in order to facilitate re-fine pulverization in the subsequent step, the roughly crushed leather powder after drying is subjected to a Victory mill, a ball mill, a colloid mill,
Finely pulverize with a dry pulverizer such as a jet mill, roller mill or hammer mill until the average particle size reaches approximately 50 μm.

Then, for the same reason, the finely pulverized leather powder obtained is subjected to gravity classification, inertial classification, centrifugal classification such as cyclone and micron separator, and fine powder (for example, average particle size D ₅₀ = Classify into coarse powder (for example, D ₅₀ = 60 μm or more) and coarse powder (thickness of 30 μm or less) The coarse powder can be circulated to the fine pulverization step as needed.

Then, a step of re-pulverizing the fine powder until D ₅₀ = 7 μm or less is performed. If necessary, the D ₅₀
A step of classifying and removing the fine powder having D ₅₀ = 2 μm or less from the fine powder having 7 μm or less is performed. The re-fine pulverization step can be carried out by a pulverizer suitable for pulverization, such as a jet mill or a colloid mill, among the dry pulverizers described above. The classifying step can be carried out by the classifier as described above.

In the above method, a series of washing operations were performed after the degreasing step, but this washing operation can be performed before degreasing or after pulverization.

The synthetic resin used in combination with the leather powder obtained as described above may be thermoplastic or thermosetting. Representative thermoplastic resins include vinyl chloride resin, vinyl acetate resin, polystyrene, ABS resin, acrylic resin, polyethylene, polypropylene, fluororesin, polyamide resin, acetal resin, polycarbonate, thermoplastic polyester resin, thermoplastic polyurethane resin, cellulose. There are plastics. Typical thermosetting resins include phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, diallyl phthalate resin, thermosetting polyurethane resin, and silicone resin.

As the rubber, diene (butadiene-styrene, butadiene-acrylonitrile), polysulfide (thiochol), olefin (ethylene-propylene, chlorosulfonated polyethylene), organic silicon compound, fluorine-containing compound, urethane, vinyl There are synthetic rubbers such as type and natural rubbers.

The leather-like molded article of the present invention has additives commonly used in this field, such as an antioxidant, an ultraviolet absorber, a processing aid, and a vulcanization agent, depending on the purpose of modification, stabilization, etc. and the purpose of use. A necessary amount of a colorant such as a curing agent; a plasticizer; a dye or a pigment, in addition to the agent and the vulcanization acceleration aid.

Examples of the antioxidant include alkylphenol, alkylene bisphenol, alkylphenol thioether, β, β'-thiopropionic acid ester, organic phosphite ester, aromatic amine, and phenol / nickel complex.

As a UV absorber, salicylate such as phenyl salicylate; benzotriazole such as 2-hydroxyphenylbenzotriazole; 2-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoctane There are hydroxybenzophenone compounds such as xybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone.

Processing aids include stearic acid, polyethylene glycol, paraffin wax and the like.

As the vulcanizing agent, sulfur such as powdered sulfur, insoluble sulfur, surface-treated sulfur, etc .; magnesium oxide, zinc, etc. (CR, CS
(For M and T); quinoid vulcanizing agents; peracid vulcanizing agents; amine vulcanizing agents; resin vulcanizing agents; organic sulfur vulcanizing agents and the like.

Examples of the vulcanization accelerator include lead dithiocarbamic acid salt and heterocyclic mercaptan.

Examples of the vulcanization accelerator include zinc white, stearic acid and the like.

The method for producing the leather-like molded article of the present invention using the above materials will be described in detail.

In advance, the moisture content of the leather powder is 0.5 wt% to prevent foaming and hydrolysis of the powder when kneading with the leather powder, usually in the form of pellet, powder, block or paste and rubber.
The dry leather powder, resin and / or rubber, and additives if necessary are kneaded at a temperature of 230 ° C or lower (material temperature) using an extruder, a Banbury mixer, a kneading roll, etc. For convenience, it is processed into pellets (see FIG. 1), powders (see FIG. 2) or blocks. Next, in order to prevent hydrolysis during molding due to moisture absorbed by the leather powder in the pellets, powders or blocks, the pellets, powders or blocks are pre-dried at 90 to 120 ° C for 5 to 12 hours or more. In this case, it is sufficient to dry the pellets or powder so that the water content is 1 wt% or less. If it exceeds 1 wt%, not only the strength of the molded product will decrease, but also silver streaks will occur on the surface of the molded product. Will be defective. In addition, when kneading and immediately molding into a block or the like, preliminary drying is not necessary. Finally, the pre-dried pellets and powders are plasticized and injected or adhered in a mold according to a known molding method to obtain various molded products. The molding temperature (material temperature) should be 230 ° C or less, 2
If the temperature exceeds 30 ° C, the leather powder will be decomposed, resulting in not only a decrease in strength of the molded product but also a bad odor. Here, typical molding methods that can be adopted are injection molding, hollow (blow) molding, compression molding,
Rotational molding and powder slush molding are available.

The above manufacturing steps are summarized in FIG.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Production of leather powder: Chunks of chrome-tanned cowhide leather (shaving leather) 1200
After disintegrating kg with a crusher (made by Hosokawa Micron) into the shape of the original shaving waste leather (max: 1 cm width x 12 cm length),
It is sent to a crusher (hammer mill made by Odate Co., Ltd .: capacity 600 kg / Hr) in order and made into a crushed leather powder with a particle size of about 10 mm or less. The water content of this coarse powder was 40 to 60 wt%.

Next, put 350 kg of this wet coarsely crushed leather powder in a vacuum dryer,
Dry until the water content is 20 ~ 30wt%. Subsequently, 270 kg of this dried and roughly crushed leather powder was put into a degreasing machine, and n-hexane was added to 1
While feeding at 00 / min, the mixture is stirred for 1 hour and 15 minutes, extracted, degreased and filtered. The residual oil and fat content in the obtained defatted coarse powder was 0.5 wt% or less.

Next, remove the residual solvent in this defatted coarsely crushed leather powder at 130 ° C, 2 kg / cm
Purge with ² G of steam until the odor of the solvent (hexane) disappears.

The degreasing machine is supplemented with 2 m ³ of room temperature water, stirred for 30 minutes, and then drained by filtration. This batch washing operation is carried out four times in total to remove free ions such as metal ions and water-soluble components in the scrap leather. The coarsely crushed leather powder after filtration and draining contained 65 to 70 wt% of water.

Next, this is transferred to a steam steamer without humidity control, and steamed with steam at 130 ° C. and 2 kg / cm ² G for 45 minutes while stirring.

Next, the steamed coarsely crushed leather powder is pre-dried for 3 hours with a dryer held at 90 ° C until the water content becomes 30-40wt%, and then dried at 45 ° C for 8 hours with a vacuum dryer to obtain a water content of 1wt%. 190 kg of the following dried coarsely crushed leather powder is obtained.

Next, this is finely pulverized for 2 hours at 1700 rpm with a fine Victory mill (manufactured by Hosokawa Micron).

Subsequently, this was classified with a cyclone classifier, and the average particle size was
35 kg of fine leather powder with D ₅₀ = about 30 μm and 155 kg of coarse leather powder with D ₅₀ = about 60 μm are obtained. The coarse leather powder having D ₅₀ = about 60 μm was circulated in the fine grinding step.

In addition, 35 kg of this D ₅₀ = about 30 μm leather powder is jet-milled (made by Seishin Enterprise Co., Ltd.) to obtain air pressure of 8 kg / cm ² G and air volume of 10
Re-pulverize under conditions of m ³ / min and throughput of 20 kg / Hr until the total amount becomes D ₅₀ ≦ 7 μm.

Finally, this was classified with a cyclone (manufactured by Seishin Enterprise Co., Ltd.) to obtain 33.25 kg of ultrafine leather powder with D ₅₀ ≦ 7 μm and D ₅₀ = 2 μ.
Obtain 1.75 kg of ultrafine leather powder (in bag filter) of m or less.

The properties of the ultrafine leather powder with D ₅₀ ≦ 7 μm (hereinafter referred to as leather powder A) thus obtained are shown in Table 1 below.

Manufacture of molded products: 30% by weight of dry leather powder A, 70% by weight of L-LDPE (linear low-density polyethylene, Moirtech 1018T manufactured by Idemitsu Petrochemical Co., Ltd.)
% So that the mixture becomes 100% and heated to 170 ° C,
After kneading, the mixture is extruded to form pellets, which are injection-molded to obtain injection-molded products (80 × 80 × 3 mm ³ ).

Molded product test: After leaving this molded product in an atmosphere of 30 ° C. and 95% RH for 24 hours, when the presence or absence of white powder generation on the surface of the molded product was checked, no white powder was generated.

Example 2 70 wt% of a thermoplastic polyurethane elastomer (Elastran C80A10 manufactured by Takeda-Bardish Urethane Industry) which was previously melted at 180 ° C. with a Banbury mixer so that the dry leather powder A produced in Example 1 becomes 30 wt%. Both were kneaded, and the obtained kneading block was made into a sheet with a kneading roll, granulated, and then molded in the same manner as in Example 1 to manufacture an injection molded product. When this product was checked by the same test method as in the example, no white powder was generated.

Example 3 To 30 wt% of the leather powder A produced in Example 1, EPDM (ethylene propylene diene methylene linkage, KELTAN 1S-50A manufactured by Idemitsu DSM) was mixed at 70 wt%. Further, 1.5 parts by weight of a vulcanizing agent was further added to 100 parts by weight of this mixture, which was kneaded with a kneading roll having a surface temperature of 40 to 60 ° C. and immediately press-molded to obtain a press-formed product (150 × 1
50 x 1 mm ³ ).

Example 4 30% by weight of the dry leather powder A produced in Example 1 was mixed with butadiene resin (RB820 manufactured by Japan Synthetic Rubber Co., Ltd.) in an amount of 70% by weight and kneaded with a Banbury mixer at 110 ° C to 130 ° C. Then, the mixture was further formed into a sheet with two rolls and then pelletized.

Next, these pellets are press-molded into press-formed products (150
× 150 × 1 mm ³ ) was produced. This was checked by the same test method as in Example 1, but no white powder was generated.

Example 5 30% by weight of the dry leather powder A produced in Example 1 had a degree of polymerization of 8
From 100 to 300 parts by weight of straight vinyl chloride resin with an average particle size of 150 to 1000 μm and 70 parts by weight of dioctyl phthalate as a plasticizer and 30 parts by weight of straight vinyl chloride resin powder for modification with a polymerization degree of 1000 to 1300 and an average particle size of 10 μm The powder slush agent is mixed with leather powder and the powder slush agent so that the powder slush agent becomes 70 wt%, and this is stirred at a temperature of 150 to 170 ° C using a Henschel mixer, and the obtained powder is heated to a temperature of 230 ° C. The mixture was poured into a mold held by, and after molding for about 10 seconds, the unmelted portion was removed and further molding was performed for 40 seconds to obtain a slush molded product (100 × 100 × 2 mm ³ ). As a result of the check as in Example 1, no white powder was found on the surface of the molded product.

Comparative Example 1 The coarsely crushed leather powder after steam purging (the leather powder raw material is chrome-tanned cowhide waste leather) is transferred to a steamer as it is without washing with water, and the coarse powder has a water content of 65 to 70 wt%. Until
The same method for producing leather powder as in Example 1 was repeated except that water was supplied, moisture was adjusted, and then steaming was performed to produce ultrafine leather powder having D ₅₀ ≦ 7 μm (hereinafter referred to as leather powder B). Leather powder B
The properties are shown in Table 1 below.

Next, an injection-molded article was manufactured in the same manner as in the molding method of Example 1 except that leather powder B was used instead of leather powder A. This was checked in the same manner as in Example 1, and white powder was generated on the surface. It was observed.

Comparative Example 2 An injection-molded article was produced by the same molding method as in Example 2 except that the leather powder B produced in Comparative Example 1 was used instead of the leather powder A, but this was checked in the same manner as in Example 1. As a result, generation of white powder was observed on the surface.

Comparative Example 3 A press-molded article was produced by the same molding method as in Example 3 except that the leather powder B produced in Comparative Example 1 was used instead of the leather powder A. This was checked in the same manner as in Example. However, generation of white powder was observed on the surface.

Comparative Example 4 A press-molded article was produced by the same molding method as in Example 4 except that the leather powder B produced in Comparative Example 1 was used instead of the leather powder A. This was checked in the same manner as in Example 1. As a result, generation of white powder was observed on the surface.

Comparative Example 5 A slush molded product was manufactured according to the same molding method as in Example 5 except that the leather powder B manufactured in Comparative Example 1 was used in place of the leather powder A. This was checked in the same manner as in Example 1. As a result, generation of white powder was observed on the surface.

Comparative Example 6 A fine leather powder having a D _{50 of} about 30 μm (hereinafter referred to as leather powder C) was produced according to the same leather powder production method as in Example 1 except that the re-pulverization step and the subsequent classification step were not performed. The properties of the leather powder C are shown in Table 1 below.

Next, an injection-molded article was manufactured in the same manner as in the molding method of Example 1 except that leather powder C was used instead of leather powder A. The surface of this molded article had a rougher feel than that of Example 1. It was a thing.

[Effect of the Invention] According to the present invention as described above, there is an effect that it is possible to provide a leather-like molded article having excellent long-term performance and quality without generation of white powder.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an example of a leather-powder-dispersed leather-like molded article of the present invention or an example of a pellet that is a raw material for manufacturing the molded article, and FIG. 2 is a diagram of the leather-like molded article. An example of the basic configuration diagram and FIG. 3 are typical manufacturing process diagrams for manufacturing the leather-like molded product. 1 ... Leather powder, 2 ... Synthetic resin and / or rubber.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Inoguchi 4-12-18 Ginza, Chuo-ku, Tokyo Idemitsu Petrochemical Co., Ltd. (56) Reference JP 1-20598 (JP, A) JP HEI 1-225665 (JP, A) JP-A-63-286500 (JP, A) JP-A-3-162500 (JP, A)

Claims (1)

[Claims] 1. A cortical component of 85 wt% or more, an oil and fat component of 2 wt% or less, a total amount of water-extractable Na ⁺ ions and Ca 2 ⁺ ions of 0.5 wt% or less, and an average particle diameter D ₅₀ of 7 μm. 1 to 90 wt% of leather powder having a standard deviation of the particle size of 3 μm or less
And at least one kind of the group consisting of synthetic resin and rubber 99 to 10
A leather-like molded product, which is mainly composed of a dispersion mixture with wt%.