JPH0418176A - Leathery formed product - Google Patents

Abstract

PURPOSE:To obtain the subject formed product having excellent long-period performance and quality without any formation of white powder by mixing specific superfine leatherdust with especially hardly any impurities with a synthetic resin and rubber. CONSTITUTION:A leathery formed product is obtained by degreasing leather to >=85wt.% cortex content and <=2wt.% content of fats and oils, regulating the total amount of Na<+> ions and bivalent Ca ions extractable with water to <=0.5wt.%, finely pulverizing the resultant leather to <=7Xm average particle diameter (D50) and <=3Xm standard deviation of the aforementioned particle diameter, classifying the powder and using 1-90wt.% prepared superfine leatherdust with 99-10wt.% synthetic resin (e.g. a thermoplastic or a thermosetting resin) and rubber (synthetic, natural rubber, etc.) together, kneading the resultant mixture and carrying out injection molding. Thereby, the objective leathery formed product having excellent long-period performance quality without formation of white powder is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a leather-like molding composition, particularly a leather-like molded product using ultrafine leather powder with few impurities, and relates to a leather-like molded product using a leather-like molding composition, and in particular a leather-like molded product using ultrafine leather powder with few impurities. , can be used for musical instruments, etc.

[Background technology]

Technology to mix leather powder made from animal hides with synthetic resin and rubber and turn it into pellets for molding (Japanese Patent Laid-Open No. 6
3-152698) or technology for forming or molding (for example, JP-A-53-12902, JP-A-63-113)
No. 11) is known.

[Problem to be solved by the invention]

However, the leather-like molded products obtained by these techniques have the disadvantage that, especially when left in a humid atmosphere for a long period of time, white powder forms on the surface of the products, deteriorating the performance and quality (appearance) of the products.

An object of the present invention is to provide a leather-like molded product that does not generate white powder and has excellent long-term performance and quality.

[Means and effects for solving the problem] The present invention focuses on the fact that ultra-fine leather powder with a specific particle size with less dull substances can prevent the generation of white powder in the commercialization of leather-like molded products. This aims to achieve the above objective.

The leather-like molded article of the present invention has a cortex content of 85 wt% or more, an oil content of 2 wt% or less, water-extractable Na+ ions and C
From 1 to 90 wt% of leather powder, synthetic resin, and rubber, in which the total amount of a''+ ions is 0.5 wt% or less, and the average particle size I) is 7 μm or less, and the standard deviation of the particle size is 3 μm or less. It is mainly composed of a dispersed mixture of 99 to 10 wt % of at least one of the group consisting of:

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

In this type of molded product, the amount of the leather powder material and at least one material from the group consisting of synthetic resin and rubber is 1% based on the mixture of these two materials.
~90 tvt%, and 99-10 wt%.

When the proportion of leather powder exceeds 90 wt%, the molded article becomes brittle, and when it is less than 1 wt%, the addition has no effect.

The reason why the characteristic values of the leather powder in the molded article of the present invention are limited is as follows.

l) Cortex content of 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 an important substance that improves the surface condition, touch feel, etc. of products mixed in leather, paint, etc. It means to be a factor. In other words, the surface condition of the product can be improved more efficiently with a smaller amount of powder when the amount of cortical material is larger.

2) Oil and fat content of 2 wt% or less (preferably 0.5 wt% or less): The oil and fat content present in animal leather deteriorates due to heat, etc., resulting in bad odor, coloring, and deterioration of the surface texture of the mixed product due to bleed-out (
(Causes sticky, slimy, shiny feeling). Therefore, the lower the oil and fat content, the better.

3) Free ions extractable with water (Na”, Ca”)
Total amount of 0.5wt% or less: Among the impurities derived from leather raw materials, if the amount of free ions extracted with water is large, when it is made into a product, it will be affected by humidity, heat, etc., and the surface of the product will be Salt (e.g. NaCl, Na
, SO, Ca5O*, etc.) bleed out, leading to deterioration of product appearance. In addition to the cations Na'' and Ca'', free ions that can be extracted with water include Cl-
, SO4"- anions exist, but what bleeds out occurs only in the form of salts of the counter ions of these ions, so the total amount of cations Na+ and Ca"+, which are small in amount, is Specified by quantity.

4) Average particle size Dao≦7μm and standard deviation σ≦3μm
= Particle size is a decisive factor for thin-walled products; if the particle size is large, it will lead to 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 (voids, thread breaks, etc.)
A product with a surface condition with good touch feeling can be obtained. Furthermore, a small standard deviation means that there are few large particles mixed in in the distribution.

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

A) Cortical content and oil/fat content: JIS K6550-1976 r Leather Test Method"6.
7 and 6.4.

B) Free ions extractable with water (Na”, Ca”)
Total amount of: A log of dried leather powder is stirred in 100% pure water all day and night to extract free ions in the leather powder. Na in the extract
Ca2+ is determined by atomic absorption spectrometry and determined as the amount extracted from leather powder.

C) Distribution of average particle size and standard deviation: Several tens of micrometers of leather powder was dispersed in 100 methanol, and the particle distribution was measured using a Coulter Counter (manufactured by Coulter Electronics). Find the deviation.

Note that the density range of leather powder is usually 0.38 to 0.43 g/
ce (after drying leather powder at 120°C for 2 hours, JIS K
6721). If the density is too large,
The particle size increases to exceed the predetermined average particle size of 7 μm, and on the other hand, if the density is too small, the leather powder becomes fibrous and has many loose hairs, making it difficult to disperse uniformly with the synthetic resin. This is because there are things.

The leather powder used in the present invention as described above can be obtained by, for example, coarsely crushing the leather powder raw material, drying, degreasing with a solvent, removing residual solvent, washing with water, dehydration, swelling treatment with steam, drying,
After performing each process of fine pulverization and classification into fine powder and coarse powder,
Further, a step of re-pulverizing the fine powder to an average particle size Dso" of 7 μm or less, and
It can be manufactured by performing a step of classifying and removing fine powder with so=2 μm or less.

To explain this manufacturing method in more detail, first, in order to facilitate fine pulverization in the subsequent process, the leather powder raw material is coarsely pulverized to a particle size of about 10 mm or less using a pulverizer such as a show crusher, cutter mill, or hammer crusher. The coarsely crushed leather powder thus obtained usually contains 40 to 60 wt% of water. Note that shaving waste leather, floor leather, etc. can be used as the raw material for the leather powder.

Next, in order to facilitate degreasing (removal of fats and oils) in a subsequent step, this water-containing coarse powder is dried until the moisture content is approximately 20 to 30 wt%.

Next, this dry coarse powder is mixed with an appropriate solvent to reduce the fat and oil content to 2w.
Degreasing is performed until the content is t% or less, preferably 0.5wt% or less. Here, n-hexane, benzine, methylene chloride, acetone, ethyl acetate, toluene, etc. can be used as the degreasing solvent.

Subsequently, in order to remove residual solvent in the coarse powder, the coarse powder after degreasing is heat treated. Since steam is usually used as the heat source for safety reasons, this process is also called steam purging. Other heat sources that can be used include heated nitrogen and heated air.

Next, free ions (Na'', Ca'
In addition to extracting and removing the strawberry, a water washing process and a dehydration process are performed in order to make the coarse powder retain a predetermined amount of moisture. It is effective to repeat this series of water washing operations several times in a batch manner. For example, a fixed amount of water is supplied to the coarse powder after the solvent has been removed, and after stirring for a desired time and bubbling with air if necessary, dehydration is performed. Depending on the amount of water supplied, it is usually done several times.
Preferably repeat 3 to 4 times. Dehydration is usually performed by filtration (draining or draining) for ease of operation, but other methods such as centrifugal dehydration may also be used. Note that continuous water washing operation requires 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.

Through the above series of water washing operations, the total amount of free Na'' ions and Ca2+ ions (dry weight equivalent) was reduced to 0.5.
A water-containing coarse powder having a water content of usually 65 to 70% can be obtained when the amount is less than wt%. As a result of this series of water washing operations, the coarse powder usually retains a predetermined moisture content (65-70%), so this method only requires checking the moisture content of the coarse powder after dehydration, which has not been done in the past. This method has the advantage that the humidity conditioning step of replenishing water until the coarse powder after removing the solvent reaches a predetermined moisture content can be virtually eliminated.

Here, the reason why a predetermined amount of water is retained or supplied to the coarse powder is as follows. That is, in a dry state, even if pulverization is performed after steam steaming in the next step, pulverization will not proceed.

However, when steam-cooked coarse powder that contains water and is swollen, it is partially denatured by heat, and when dried, it becomes compact and hard, making it easier to crush and pulverize.

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

Subsequently, in order to facilitate fine pulverization in the subsequent step, the coarsely crushed leather powder after the swelling treatment is dried until the moisture content is approximately 3 wt % or less. This drying step is usually performed by combining preliminary drying using a dryer and main drying using a vacuum dryer.
□ Next, in order to facilitate re-pulverization in the subsequent process, the coarsely crushed leather powder after drying is processed in a victory mill, ball mill, colloid mill,
Finely pulverize using a dry pulverizer such as a jet mill, roller mill, or hammer mill until the average particle size is approximately 50 μm.

Next, for the same reason, the obtained finely pulverized leather powder is passed through a gravity classifier; an inertial classifier; a centrifugal classifier such as a cyclone or a micron separator; = 30 μm or less) and coarse powder (
For example, D5o=60 μm or more). Note that the coarse powder can be recycled to the pulverization step as necessary.

Subsequently, the fine powder was added until Dso = 7 μm or less,
After re-pulverizing, a step is carried out to classify and remove fine powder of D5゜=2 μm or less from the fine powder of Dso'''7 μm or less. This can be carried out using a suitable pulverizer such as a jet mill or a colloid mill. Furthermore, the classification step can be carried out using a classifier as described above.

In the above method, a series of water washing operations were performed after the degreasing step, but this water washing operation can also 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. Typical 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, and cellulose. There are plastics, etc. Typical thermosetting resins include phenolic resin, urea resin, melamine resin,
Examples include unsaturated polyester resins, epoxy resins, diallyl phthalate resins, thermosetting polyurethane resins, and silicone resins.

Rubbers include diene (butadiene-styrene, butadiene-acrylonitrile) and polysulfide (thiocol).
, olefin-based (ethylene-propylene, chlorosulfonated polyethylene), organosilicon compound-based, fluorine-containing compound-based, urethane-based, vinyl-based synthetic rubber, and natural rubber.

The composition of the present invention may contain additives commonly used in this field, such as antioxidants, ultraviolet absorbers, processing aids, vulcanizing agents, etc., depending on the purpose of modification, stabilization, etc., and the purpose of use. In addition to the vulcanization accelerating aid, a curing agent; a plasticizer; and a coloring agent such as a dye or a pigment can be added in necessary amounts.

Examples of antioxidants include alkylphenols, alkylene bisphenols, alkylphenol thioethers, β,β'-thiopropionic acid esters, organic phosphite esters, aromatic amines, and phenol/nickel complexes.

As ultraviolet absorbers, salicylic acid esters such as phenyl salicylate; hydroxybenzophenones such as 2-hydroxybensitrial; 2-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-oct There are hydroxybenzophenones such as xybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone.

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

Vulcanizing agents include sulfur such as powdered sulfur, insoluble sulfur, and surface-treated sulfur; magnesium oxide, zinc, etc. (CR,
Examples include metal oxides such as C3M and T); quinoid vulcanizing agents; peroxide vulcanizing agents; amine vulcanizing agents; resin vulcanizing agents; and organic sulfur vulcanizing agents.

Examples of vulcanization accelerators include lead dithiocarbamate salts and heterocyclic mercaptans.

Examples of vulcanization accelerating aids include zinc white and stearic acid.

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

In advance, the water content of the leather powder is reduced to 0.5w to prevent foaming and hydrolysis of the powder when kneading the leather powder with resin and rubber in the form of pellets, powders, blocks, or pastes.
This dried leather powder, resin and/or rubber, and additives if necessary are kneaded at a temperature of 2308C or less (material temperature) using an extruder, Banbury mixer 1 kneading roll, etc., and then molded. For convenience of processing, it is processed into, for example, pellets (see Figure 1), powders (see Figure 2), or blocks. Next, in order to prevent hydrolysis during molding due to moisture absorbed by the leather powder in the pellets, powder, or block, the pellet, powder, or block is
Pre-dry at 0°C for 5-12 hours or more. In this case, it is sufficient to dry the pellets or powder so that the moisture content is 1 wt% or less; if it exceeds 1 wt%, not only will the strength of the molded product decrease, but also silver streaks will occur on the surface of the molded product. This will result in a defective product. Note that preliminary drying is not necessary if the product is immediately formed into a block shape or the like after cross-wiring. Finally, various molded products are obtained by plasticizing the pre-dried pellets or powder and injecting or adhering them into a mold according to a known molding method. Molding temperature (material temperature) is 230
The temperature is preferably below 230°C, and if it exceeds 230°C, the leather powder will decompose, resulting in not only a decrease in the strength of the molded product but also a bad odor. Typical molding methods that can be employed here include injection molding, hollow (blow) molding, compression molding, rotational molding, powder slush molding, and the like.

The above manufacturing process is summarized in FIG. 3.

〔Example〕

The present invention will be explained in more detail below with reference to Examples.

Fruit 1 - Production of epithelial leather powder Lump of nichrome tanned cowhide waste leather (shaving leather) 12
00kg was crushed using a crusher (manufactured by Hosokawa Micron Co., Ltd.) to the original shape of shaving waste leather (max: lcm width x 12C)
After loosening the leather into a coarse leather powder having a particle size of about 10 mm or less, it is sequentially fed into a coarse crusher (hammer mill manufactured by Odate Co., Ltd., capacity: 600 cg/hr). The moisture content of this coarse powder was 40 to 60 wt%.

Next, 350 kg of this wet coarsely crushed leather powder is placed in a vacuum dryer and dried until the moisture content becomes 20 to 30 wt%. Subsequently, 270 kg of this dry coarsely crushed leather powder was put into a degreasing machine,
N-hexane was stirred for 1 hour and 15 minutes at a rate of 100 f/min, extracted, defatted, and filtered. The residual oil and fat content in the obtained coarse defatted powder was 0.5 wt% or less.

Next, the remaining solvent in this defatted coarsely crushed leather powder was heated at 130°C.
Solvent (hexane) with steam of 2 kg/crl G
Purge until the odor is gone.

Add 2 bottles of room temperature water to the same degreasing machine, stir for 30 minutes, and then drain the water by filtration. This batch water washing operation is carried out four times in total to remove free ions such as metal ions and water-soluble components in the waste leather. Crushed leather powder after filtration and draining is 65-70wt%
contained water.

Next, without adjusting the humidity, transfer it to a steam steamer and heat it with steam at 130℃ and 2kg/cnfG while stirring.
Steam for 5 minutes.

Next, the coarsely crushed leather powder after steaming was pre-dried in a dryer maintained at 90°C for 3 hours until the moisture content was 30 to 40% by weight, and then dried in a vacuum dryer at 45°C for 8 hours to reduce the moisture content to 1.
190 kg of dry coarsely crushed leather powder with w1% or less is obtained.

Next, this was pulverized using a Fine Victory Mill (manufactured by Hosokawa Micron Corporation) at 1700 rpm for 2 hours.

Subsequently, this was classified using a cyclone classifier to obtain 35 kg of fine leather powder with an average particle diameter of about 30 μm and D5
155 kg of coarse leather powder with a diameter of 0 to about 60 μm are obtained.

Furthermore, D. Coarse leather powder of approximately 60 μm was recycled to the pulverization step.

Furthermore, 35 kg of this leather powder with D6o = approximately 30 μm was processed using a jet mill (manufactured by Seishin Enterprise Co., Ltd.) at an air pressure of 8 kg.
/ c/ G, air volume 10 rrr/mim, throughput 2
It is re-pulverized under the condition of 0 glare/Hr until the total amount becomes D6o≦7 μm.

Finally, this is classified using a cyclone (manufactured by Seishin Enterprise Co., Ltd.) to obtain 33.25 kg of ultrafine leather powder with D60≦7 μm and 1.75 kg of ultrafine leather powder (in a bag filter) with Dso=2 μm or less.

This is how you get it. The properties of the ultrafine leather powder (hereinafter referred to as leather powder A) of ≦7 μm are shown in Table 1 below.

Manufacture of molded products.

L-LDPE (linear low-density polyethylene, Idemitsu Petrochemical Co., Ltd. Moretic 10) was added to 30 wt% of dry leather powder A.
18T) was mixed so that the amount of
x3m”).

Test of molded product: After the molded product was left in an atmosphere of 30° C. and 95XRH for 24 hours, the surface of the molded product was checked for white powder, and no white powder was found.

Example 2 Thermoplastic polyurethane elastomer (Elastlan C8C80AIO manufactured by Takeda-Birdish Urethane Industries) 70% melted in advance at 180°C in a Banbury mixer
In contrast, the dry leather powder A produced in Example 1 was 30 wt%.
The obtained kneaded block was made into a sheet using a kneading roll, and after granulation, it was molded in the same manner as in Example 1 to produce an injection molded product.

When this product was checked using the same test method as in the example, no white powder was found.

Example 3 EPD was added to 30 wt% of leather powder A produced in Example 1.
M (ethylene-propylene terpolymer) (Idemitsu DS
KELTAN 15-50A manufactured by Company M) was mixed to 70 wt%, 1.5 parts by weight of a vulcanizing agent was added to 100 parts by weight of this mixture, and the mixture was heated to a surface temperature of 40% by weight.
Knead with kneading rolls at ~60°C and immediately press-form the product to obtain a press-formed product (150X 150X 1 mm3)
get.

Fruit 1d1 Soil 70wt of butadiene resin (RB820 manufactured by Japan Synthetic Rubber Co., Ltd.) to 30wt% of the dried leather powder A produced in Example 1.
%, and heat this at 110°C to 13°C.
The mixture was kneaded in a Banbury mixer at 0°C, and then formed into a sheet using two rolls, and then pelletized.

Next, this pellet was press-molded to form a press-formed product (15
0X 150X 1 mm3) was produced. This product was checked using the same test method as in Example 1, and no white powder was found.

Example 5 To 30 wt% of the dried leather powder A produced in Example 1, 100 parts by weight of straight vinyl chloride resin with a degree of polymerization of 800 to 1000 and an average particle size of 150 μm, 70 parts by weight of dioctyl phthalate as a plasticizer, and a degree of polymerization of 100 to 1300 A powder slush agent consisting of 30 parts by weight of straight vinyl chloride resin powder for modification with an average particle size of 10 μm.
Mix leather powder and powder slush agent so that the concentration is 0 wt%, and mix this with a Henschel mixer to 150% by weight.
Stir at a temperature of ~170°C and the resulting powder at a temperature of 230°C.
The mixture was injected into a mold maintained at a temperature of C, and after molding for about 10 seconds, the unmelted portion was removed and molded for an additional 40 seconds to obtain a slush molded product (100 x 100 x 2 squares). As a result of the inspection, no white powder was found on the surface of the molded product, as in the case of several tests.

Comparative Example 1 Crushed leather powder after steam purging (leather powder raw material is chrome-tanned cowhide) is directly transferred to a steamer without washing with water, and the moisture content of this coarse powder becomes 65 to 70 wt%. After replenishing water and controlling the humidity, the same method for producing leather powder as in Example 1 was repeated, except that the steaming was performed until D50≦7 μm.
An ultrafine leather powder (hereinafter referred to as leather powder B) was produced.

The properties of leather powder B are shown in Table 1 below.

Next, an injection molded product was produced in the same manner as in Example 1 using leather powder B instead of leather powder A, but when this product was checked in the same manner as in Example 1, white powder was observed on the surface. It was observed.

Comparative Example 2 An injection molded product was manufactured in the same manner as in Example 1, except that leather powder B produced in Comparative Example 1 was used instead of leather powder A. As a result, white powder was observed on the surface.

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

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

Comparative Example 5 A slush molded product was manufactured in the same manner as in Example 1, except that leather powder B produced in Comparative Example 1 was used instead of leather powder A. As a result, white powder was observed on the surface.

51 D50" approximately 30μ according to the same leather powder manufacturing method as in Example 1 except that the re-pulverization process and the subsequent classification process were not performed
m fine leather powder (hereinafter referred to as leather powder C) was produced.

The properties of leather powder C are shown in Table I below.

Next, an injection molded product was produced in the same manner as in Example 1 using leather powder C instead of leather powder A, and the surface of this molded product had a rough texture compared to that of Example 1. It was something.

Table 1 [Effects of the Invention] According to the present invention as described above, it is possible to provide a leather-like molded product having excellent long-term performance and quality without generating white powder.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of an example of a leather powder-dispersed leather-like molded product of the present invention or an example of a pellet that is a raw material for manufacturing this molded product, and FIG. 2 is a basic configuration diagram of an example of the leather-like molded product. 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.

Claims (1)

[Claims] (1) Cortex content is 85 wt% or more, oil content is 2 wt% or less, total amount of water-extractable Na^+ ions and Ca^2^+ ions is 0.5 wt% or less, and average particle size D_5_
0 is 7 μm or less and the standard deviation of the particle size is 3 μm or less, and is mainly composed of a dispersion mixture of 1 to 90 wt% of leather powder and 99 to 10 wt% of at least one of the group consisting of synthetic resin and rubber. A leather-like molded product.