KR810001057B1 - Manufacture of leather - Google Patents

Abstract

Grain and split leathers were prepd. by pretanning hides with chrome-free tanning liquors until the shrinkage temp. (Ts) was 170oF-180oF, splitting the pretanned hides to grain and split intermediates, shaving the intermediates, and chrome-tanning the shaved intermediates. Thus, 665Lb cowhides were soaked, unhaired, bated, and washed in the usual way, pickled in formic acid and NaCl to pH 5.3, and pretanned 30 min at 80oF in 11.25Lb HELATAN 9501 (phenolic-glutaraldehyde pretan) and 5 gal H2O to Ts 176oF. After splitting and shaving, the splits were chrome-tanned and finished in the usual way.

Description

How to treat leather

The present invention relates to a method for treating leather used in shoes, upholstery, and clothing.

The production of silver and split leather is a tannery that does not contain chromium due to the nature of the raw skin. When the pre-tanning is performed, the shrinkage temperature is about 178 ° to about 185 ° F. It is then summarized by dividing this pretanning skin into a gin intermediate and a pretanning split intermediate, shaving at least one of these intermediates, and chrome tanning the shaved intermediate. The material collected by shaving does not contain chromium, so it does not cause any special environmental pollution problems and can be disposed of as it is. The raw hides can also be pickled before dividing to improve dividing and shaving, and for long distance transportation, it is preferable to carry out raw hides without dividing and shaving. The whole process of raw skin treatment, which puts a series of raw materials in a container such as a rotating drum, can be divided into two stages. In the first stage, hair loss, deliming, and pickling pre or tanning, and in the second stage, finishing Tanning, dyeing and eggplant are performed. The final chrome tanning product has very good physical properties including abnormally high slot tears and is recovered in high yield.

It is an object of the present invention to provide an improved leather produced according to the novel leather manufacturing method as well as a process for producing the same.

Other objects than the above object of the present invention can be understood in more detail by describing the following several examples.

According to the present invention, the production of silver and split leather from raw hides, such as cowhide, is a tannery that does not contain chromium in its raw material, when the pre-tanning is reduced to about 170 to about 185 ° F. By dividing the pre-tanned raw material into pre-tanned silver noodle intermediates and pre-tanned split intermediates, shaving at least one of the intermediates to a uniform thickness, and then chromed the shaved intermediates. It is improving.

The above-mentioned preparation is particularly advantageous when producing chrome tanned silver leather. After shaving, the shaving waste discharged before chrome tanning can be disposed of as it is because chromium is not mixed and there is no environmental pollution problem. Since the waste material of such waste shavings does not contain a large amount of river pollutants, it can be directly discharged to the stream.

Waste from raw hides prior to chrome tanning can also be disposed of immediately as it does not contain chromium.

The pretanning of raw hides also greatly reduces the decay of the above-mentioned waste materials.

The pre-tanning of the present invention is usually performed after depilation and demineralization of the carcasses or the like, and these three processes can be carried out on raw hides loaded in a single container with the associated washing, in this case preliminary There is no need to remove the raw material from the container until the tanning is complete. The raw hides can be pickled before, during or after the pretanning by placing them in a container, and the pretreatment with or without pretanning can take several weeks to transport the raw skins. When transported to geographically distant provinces, transportation can be carried out without risk of deterioration of the material. The raw hides which have been acid deposited or pretanned after acid deposition are preferably packaged in a water resistant plastic sheet so as not to be dried during transportation.

In addition, the pretanning and acid deposition of the hides is made more evenly, and thus the planetary silver and split leather are both very close to the desired weight.

Since the market characteristics of the silver leather are very different from those of the split leather, it is desirable to have different finishing finishes for the silver intermediate and the divided intermediates of the present invention, and such finishing finishes can be implemented in various parts of the world. When both of these intermediates are subsequently chrome tanned, shaving can be done before chrome tanning and before transportation in order to improve the discharge of shaving waste from both intermediates.

When producing heavy leathers weighing more than 4 ounces, many heavy leathers have a wide thickness range, so that shaving can be minimized or omitted entirely.

Since chrome tanned leather articles produced by the above technique have particularly high groove tear values (usually 13 or more in 2 1/2 to 3 hot leather), these articles are very desirable for applications where tearing is a problem. In addition to this very advantageous feature, the leather articles of the present invention have good tensile strength, good breaking strength and complete flank compared to chrome tanned leather according to the prior art.

This improved physical property may be due to the combination of the separate tanning process, the splitting process and the shaving process. Since the splitting and shaving operations are quite rigorous mechanical treatments, this treatment reduces the stringency of such mechanical effects on the fibrous fibers after pretanning. In addition, chrome tanning is more effective because the finishing tanning is performed on a base material that is relatively thin and stretched as a result of the dividing and shaving operations. In fact, there is generally no need to repeat chrome tanning, thus reducing the use of secondary chrome tanning, which is often used in the prior art.

The relatively small amount of chromium tanning agent required in the present invention is emphasized by the fact that chromium tanning agents are used only for shaved substrates, so that the total amount of such chemicals is reduced in proportion to the shaving waste weight. The recycling and reuse of chrome tanning agents is also reduced. The cost of chrome tanning agents is generally the most expensive agent for skin tanning, and disposal of used tanning liquors is the most problematic.

The stretching action described above also increases the amount of leather produced from the hide when the amount of leather is measured by surface area. This increase is at least 3% compared to standard lime dipping or at least 5% compared to prior art Blue Spliting tanning techniques.

The mechanical process of the production method of the present invention can be carried out in the same manner as that usually performed in the prior art. However, the shaving process in the manufacturing method of this invention requires special attention when it is carried out on the raw skin which pre-tanned without prior deposition. The shaving device of the hides generally includes an automatic feeding system that can control and adjust the speed of moving the hides through a series of spiral knifeedges that rotate at a high speed. In order to maintain the best condition of shaving or split intermediate shaving, this feed system adjusts the feed at a speed of 45 feet or less per minute. If the feed rate is higher than this, the pre-tanned finely immersed silver surface or divided intermediate is subjected to tensile force by the threaded blade, so that the silver surface or divided intermediate is unreasonably shaved.

However, the pre-tanned silver immersed silver and split intermediates according to the present invention can be shaved very efficiently even if the feed rate required exceeds no more than 55 feet / minute without any problem and regardless of thickness.

It is also difficult to shave when pre-tanning the silver and split intermediates until the fat liquor adsorption amount is about 1/4 to about 3/4% before or after shaving. Easier

Example 1

In a 4 x 8 foot rotary wood-cut rotating drum, the initial weight total was 665 pounds to demineralize the large skins of saline-cured bulls and cows treated with hydrotherapy (hair loss and hair loss). The final pH of the deliming solution is 7.4 (starting pH is 8 when measured with phenolphthalene) and the final temperature is 89 ° F. The used deliming liquid is discharged and the raw hides are given through 75 ° F water flowing into the drum at a rate of 100 gallons / minute, and the raw hides are washed without washing the raw hides from the drums and subjected to the next process.

(a) 19 gallons of 80 ° F. water followed by 60 pounds of normal salt (or equivalent equivalent of saline), 7 1/2 pounds of sodium formate and 12 ounces of bromohydroxyacetophenone biocide (Biccide) Then operate the rotating drum for 10 minutes.

(b) Stop the drum to read the salimeter reading and adjust it to 28 ° (if necessary, add more salt, sodium formate or water to adjust this value), then start the drum again and run 5 gallons of water. 3 3/4 pound formic acid diluted beforehand is added, and the drum is stopped after 30 minutes of operation. The liquid pH at this time is about 5.3.

(c) 11 1/4 pounds of HELATAN 9501 (this is a condensation product of aldehyde pre-diluted with 5 gallons of 80 ° F. water and sulfonated phenolic pre-tanning agent) and then run the drum for 30 minutes.

(d) add 3 3/4 pounds of nonionic emulsion mixture of crude and synthetic liquor solution which is stable in the presence of acidic electrolyte and has a pH of 5.5 to 6, and the drum is further operated for 30 minutes. . The oil in this liquor solution enables internal lubrication during pretanning by synthetic tanning agents (Syntan) and thus serves as a secondary part in splitting and shaving.

(e) Slowly add 7 1/2 pounds of formic acid (or 95% sulfuric acid) diluted with 10 gallons of water, then run the drum for an additional hour.

(f) The liquid has a pH of 2.8 to 3 and a temperature of 83 ° F. A small amount of fertilization is cut from the raw skin and tested by an automatic shrinkage tester to determine its shrinkage temperature. Samples are submerged in water, where the temperature rises to 5 ° F./minute. In this case shrinkage starts at 176 ° F.

(g) Next, take the raw skins from the drum and extend them overnight by hanging on a plate.

(h) The next morning, the hides are removed from the plates and split according to the tanning requirements, after squeezing out the moisture and shaving both the silver and broken pieces. The splits are adjusted to obtain 4 1 / 2-5 ounce split leather and the shaving of the silver side is adjusted to obtain a 2 1 / 2-2 ounce product. The split intermediate is shaved to 4 1 / 2-5 oz. The feed rate to the shaving device is about 55 feet / minute for both the silver face and the split face. The total weight of the silver is 166 pounds and the split leather is 110 pounds. In this regard, the pretanned and acid-divided split intermediates are ready for the next treatment or transport step and release the wastes obtained as a result of shaving.

(i) Chrome tanning in small rotating drums. To the empty drum are added 12 gallons of 100 ° F. water, 3 1/2 pound common salt and 13 temperature sodium formate.

(j) Then, put the shaved silver intermediate in this drum and operate the drum for 10 minutes.

(k) Then add 1 pound of formic acid diluted with 1 gallon of water and operate the drum for 1/2 hour.

(1) The drum is stopped, 15 pounds of commercial basic sulphate containing 23.5 chromium oxide equivalents is added and the drum is then operated for 2 hours.

(m) 13 gallons of sodium bicarbonate dissolved in 1 gallon of 90 ° F. water are then added in two equally 30-minute intervals.

(n) The drum is operated again for 1 hour at a pH of 3.6 and a temperature of 104 ° F. Samples cut from silver intermediates do not undergo any area shrinkage when immersed in boiling water for 2 minutes. If the sample does not pass the shrinkage test, the liquid is discharged from the drum. In this case, the drum is operated for another 30 minutes before discharging the liquid. In addition, sodium bicarbonate may be added, but the pH will not be higher than 3.8.

(o) In this way the chrome tanning is completed and the silver side is very smooth. The coloring operation is continued in the same drum according to the requirements of the tanning (kinds of leather and color requirements).

(p) For example, leather is first washed for 15 minutes with water between 90 ° F and 100 ° F. Aqueous sodium bicarbonate or other neutralizing agents (eg ammonium bicarbonate, sodium formate, etc.) are then added to bring the pH to 4.8-5.5.

(q) Wash the drum contents again with water at 110-120 ° F for 15 minutes, drain the wash and then add 25 gallons of 130 ° F water (100% frit) followed by 12 ounces of nonionic egg liquor stable to the electrolyte (加 脂 額) is mixed with 2 gallons in 130 ° F water.

(r) where the drum is operated for 30 minutes, then pre-dissolved in water of 170 to 180 ° F., 1/2 of a 1: 1 mixture of acid and direct dye, diluted to form a 1 1/2 gallon 130 ° F. solution. Add pound brown aniline dye.

(s) The drum is continuously operated for 30 minutes, 1/2 pound formic acid dissolved in 1/2 gallon cold water is added, and the drum is further operated for 15 minutes.

(t) In this case, the sample of the dyeing product is examined to check the color and uniformity of the color, and if necessary, additional dye is added to operate the drum for 15 minutes to 1/2 hour.

(u) Release the used dye solution, wash the dyed leather for 15 minutes with 130 ° F radish, add water to 100% Float level, and add 5 pounds of synthetic sperm whale oil in 130 gallons of 4 gallons. (Sperm Oil), 5 pounds of sulfated right angle oil and 1/2 pound crude right angle oil are added to the liquor mixture. Operate the drum for 1 hour to inspect the waste oil and leather to ensure that the liquid is clear and that the leather is free of oil stains.

(v) The liquid is discharged, the branched leather is washed with cold water for 5 to 10 minutes, the contents are removed from the drum, and the taken out leather is stretched on a drying rack.

The pretanning agent in example 1 of US Pat. No. 3,480,379 may be used in place of the pretanning mixture in process (C), but this is not so efficient. Shrinkage temperatures tend to be lower and more pretanning agents are generally needed.

In order to tan the shaved divided intermediate of the above example, the above-described chrome tanning (steps j to n) may be used, but as a separate method, the zirconium tanning agents described in US Pat. Nos. 3,423,162, 2,970,031 and 3,232,696 Tanning methods by other minerals such as aluminum tanning agents, or Vol. Of the Journal of the American Leather Chemists Association. 54 pages 488 to 502 and 668 to 674; Vol. 59 pages 281 to 292 and 378 to 402; Vol. 62 pages 507-522; Vol. 64 with Vol. 227-239. 70 Chapter 22 of The Chemistry of Leather Manufacture, published by McLanghlin Theis, with glutaraldehyde, such as those described by Mr. Filachione et al. On pages 269-272, or with plant tannery such as Gumbraco, Watttle, Smak or Chessnel. Combined tanning of resin-synthetic tanning can be used as described in pages 693 to 722). Depending on the type of leather to be produced, these tanning agents may be used alone or in combination with each other.

For most leathers, chrome tanning is very desirable or simple and convenient to implement, but the inventive process does not require chrome tanning of both warm and split surfaces.

Example 2

The operation of Example 1 is repeated through the step (h) of Example 1, using a very small rotating drum and a batch of two bull hides (weight after hydration is 135 pounds). Although the total amount of chemicals and water was reduced to 1/5 of the amount of the base material of Example 1, the following matters were different.

Except for (A) step (b), the pH after step (d) is about 6.8.

(B) In step (e), 2 1/2 pounds of 96% sulfuric acid (or 3 1/2 pounds of formic acid) diluted in 5 gallons of water are added twice at 20 minute intervals, and the drum 1 1/2 After operating for 1 hour and stopping for 1 hour, operation is performed for another 1/2 hour.

(C) The shrinkage temperature after pretanning is about 177 ° F. and the splitting and shaving are adjusted to obtain silver leather weighing 3 1/2 to 3 3/4 ounces. The weight after shaving of silver leather is 52 pounds in total, and the split leather is 20 pounds in total, shaved to 3 1/2 to 4 ounces.

Example 2A

The silver leather prepared in Example 2 was placed in a small drum, and therein, 3 gallons of 75 DEG F. water, 1 pound of salt, 8 ounces of sodium formate, 45 g of biocide 0-phenoxyphenol Processing can be continued.

The drum is operated for 10 minutes, and then 1/4 pound formic acid dissolved in 1/2 gallon of water is added, and the drum is rotated for 1/2 hour. Four pounds of commercially available basic chromium sulfate containing 23.5% of chromium oxide equivalents are added and the drum is operated for one hour. Subsequently, 1/2 pound of cationic egg oil emulsified in 120 gallon of 1/4 gallon water is added, and the drum is operated for 15 minutes. 1 1/4 pounds of commercial glutaraldehyde tanning agent (such as Relugan GTW 50 or Chemtan 55) is added in equal amounts three times at 20 minute intervals and the drum is then operated for 2 hours. Three equal quarters of sodium bicarbonate dissolved in 1 gallon of 90 ° F. water is added three times at an interval of 30 minutes, and the drum is operated between them and finally operated for one hour. In this test the temperature of the drum contents is 106 ° F and the pH is 3.7.

Samples cut from warm hides do not shrink at all, even if soaked in boiling water for 2 minutes, and thus voodoo is completed here. The tank can be resisted to flush and reuse the liquid from the drum and the tanning product can be washed and the coloring can continue.

This post-treatment process can be processed as is without removing the chrome tanned product from the drum. Thus, one suitable process that can be used in the present invention is to wash the chrome tanned product for 10 minutes with 110 ° F. water, then add the gallons to 110 ° F. of 6 gallons at 100% suspension and then to 3 gallons 110 ° F. water. Dissolve 1 1/2 pound sodium vinegar and 1/2 pound sodium bicarbonate equally three times at 20 minute intervals, and then operate the drum for 40 minutes. The pH at this time is 4.9-5 and the product is washed with 110 ° F. for 10 minutes. Where the workpiece is placed in 100% suspension, 6 gallons 110 ° F water, 8 ounces TAMOL SD synthetic tanner, 1 1/2 pound watt and 2 pound phenolic synthetic tanner (Basyn than DLE, Chemtan E 17 or Tru) tan 1776 K or other resin or vegetable extract) and operate the drum for 40 more minutes. It is then washed with 120 DEG F. for 10 minutes and the operation is continued with the selected dyes and egg oils.

One efficient finishing technique involves adding 8 ounces of mixed direct acid red dye (the same) diluted to predissolve in 150 ° F 120 ° F water and 170 to 180 ° F water to form a 1 gallon 130 ° F solution. will be. The drum is operated for 30 minutes, then 1/4 pound formic acid diluted in 1/2 gallon water is added, and then the drum is operated again for 15 minutes. After stopping the drum, check the chromaticity and dye release of the workpiece. Here the workpiece is washed with 130 ° F water for 10 minutes and then drained. Add 130 ° F water to 100% suspension, 1 1/2 pounds of synthetic sperm whale oil, 1 1/2 pounds of sulfated hump oil and 2 1/2 pounds of solvent oil in 130 gallons of 3 gallons. The egg oil mixture prepared by emulsifying (for example, industrial gasoline) is added, and the drum is operated for 1 hour. In order to ensure that oil is absorbed by the leather and that the leather is not between the oils, the drum is stopped to check for oil release and leather. The leather is washed for 10 minutes with 70 ° F. radishes, taken out and dried on a overnight plate.

Example 2B

The split leather of Example 2 is charged into a small test standard drum and the following processing is carried out.

(I) 2 gallons of saturated saline, 0.1% (9 g) of biocide is added and the drum is operated for 10 minutes.

(II) 1.75% (5/2 ounce) of 96% sulfuric acid diluted in 1 gallon of water was added in equal amounts twice at 15 minute intervals, and between these additions and for 1 1/2 hours after addition. Operate the drum.

(III) Then, the drum was stopped and maintained for 1 hour at which time the pH was 1.7 to 1.8.

(IV) The drum is discharged and recovered in the previous chrome tanning operation and 1 1/2 gallon chrome tanning containing 6 to 8 g / 1 of chromium oxide (calculated in Cr ₂ O ₃ ) and 3 ounces of sodium formate. Add the liquid.

(V) The drum is operated for 1 hour, then 1 pound 3 ounces of commercial chromium sulfate containing 23.5% of chromium oxide equivalents is added and the drum is further operated for 2 hours. Chromium tanning and post-treatment are continued as described in Example 1 (steps m to v) or as described below.

(VI) Five ounces of sodium bicarbonate dissolved in 6 gallons of water are added in triplicates (2 gallons every 30 minutes) and the drum operation is continued for another hour. At this time, the pH was 3.5 ° F and 104 ° F, and the hard samples from split leather showed no shrinkage after 2 minutes in boiling water.

(VII) where the chromium tanning liquor deposited in the drum is discharged and pumped to the tank for recycling. The sufficiently tanned split leather in the drum can be washed or adsorbed and branched with 90 ° F. for 10 minutes to make a good Suede split product. In order to produce a finished product having greater water resistance, the eggplant is preferably made with the same composition as in German Austegeschrift 2,355,025.

Example 3

Another experiment was carried out with 20 ox hides (weight 1540 pounds) using the operation of Example 1 on a 4 x 8 foot rotating drum, doubling the amount of chemicals, and the steps (a) to (e) Subsequent tanning with 23 pounds of mixed sulfonated phenol-alkylated phenol-formaldehyde condensate pretanning agents at 50% suspension, pH 7-9 and 85 ° F. The drum is operated for 45 minutes and stopped for 30 minutes. The shrinkage temperature at the completion of this pretanning is 172 ℉. After chrome tanning, the tanning and branching can be done as in Example 2A to produce warmth, upholstery and handbag leather with very good lubricity. In addition, according to this order, a split leather is produced which is very suitable for insoles, belts and laminates.

In addition, according to the present invention, so-called shrunken leather can also be produced. Thus, after pretanning, splitting, dehydration and shaving, the cotton wool is prepared by dihydroxydiphenylsulfone resin, as described in US Patent No. 3,010,779 by E. Komarek and G. Mauthe, or by SS Lipowski as US Patent No. As described in US Pat. No. 3,477,801, it shrinks as in the treatment with the condensation product of diphenylsulfone with formaldehyde and naphthalenesulfonic acid. The shrinkage intermediates can then be washed and finished or final tanned without finishing. The final product is completely tanned and features distinctive shrink leather. An example of this shrinkage deformation is found to eliminate the need for many charging and withdrawing steps.

Example 4

The following correction is made and the operation of Example 1 is repeated. A small rotating drum is used with a total weight of 130 pounds of 2 bull hides and a 1/5 drug batch. After process (e) the pH is 2.9 and the temperature is 86 ° F. 3 pounds of commercial 50% glutaraldehyde tanner or preferably Helatan 9502 is added and the drum is operated for 30 minutes and stopped for 30 minutes. The shrinkage temperature is 174 ° F. and the pH is 3.4. Here, operation of Example 1 is started again from a process (g).

Any technique may be used to prepare the raw skin for pre-tanning of the present invention, and this preparation technique is described in the Journal of the American Leather Chemists Association (1974) Vol. It is described on pages 69, 28 and 43. Next, a preferred embodiment is described, and all of the drugs are based on the weight of the original Flesh Hide.

Example 5

Soaking

The brine cured skin pre-grown in 70-80 ° F containing 0.2% sodium hydroxide is immersed at 5 to 6 o'clock at 100% retention level. 2 hours).

For this immersion, a simple rotating drum or hide process drum or a conventional Hagspiel or Corretan Drum assembly can be used.

Hair loss

The immersion is then discharged and the hides washed as a second fill of 70 to 80 ° F. water, and a third water fill (containing 1% sodium sulfide hydrate Flake) is suspended 100% at 75 to 80 ° F. Introduce to the level. There, the drum is rotated for 1 hour.

At this point the drum is stopped, 1.5% sodium sulfide + 2.5% lime is added, the drum is further operated for 1 hour, the drum is then stopped for 1 3/4 hours, and then operated for 1/4 hour to start this 2 hour stop-start. The operation is repeated six times or more, and then the liquid is discharged. If the original raw material is very fat, 0.2 to 0.25% of degreaser, preferably nonionic alkalphenyloxypolyethoxyethanol, such as ＂Trition × 114＂, may be added to the immersion or hair loss liquid or both. have.

Here, if the hair loss solution is to be released and a very soft leather is produced, the raw hides can be soaked for at least 8 hours in 70 ° F water containing 1 to 30% lime at a floating level of at least 100%.

Demineralization

The hair loss hair was washed for 10 minutes in a flow of 85 to 90 ° F., and then 50% suspended in 90 ° F. water containing 2 1/2% of a mixture of 30 parts of ammonium sulfate, 40 parts of ammonium chloride and 30 parts of sulfophthalic acid. Deliming treatment at the level is performed. After the drum was rotated for 1/4 hour in this liquid, the drum was stopped and 0.07% of Oropon WN 4 pancreatic demineralizing enzyme was added to the liquid, and the drum was operated for 3/4 hours. Here again, 0.2% of nonionic degreaser and 0.3% of sodium bisulfite are added to the liquid. The drum is then operated for another 40 minutes to complete the deliming treatment. At this time, the liquid having 8 to 8.3pH was discharged and the raw skin was washed with water at 70 to 75 ° F. for 20 minutes to wash the lime salt and to cool the treated raw material. The product is ready for pretanning.

Any treatment of the above examples may be applied, and alternatively, the pretanning of Example 1, such as that performed at 7.5 pH, may be denatured, and then acid deposition may be performed separately after the pretanning solution is discharged. Suitable acid treatments for this purpose are used at 60% suspension with 80 ° F water containing 2.5% sodium chloride, 1% sodium formate and 0.1% biocide, and 10 minutes After mixing, a commercial acidic acid such as 1 1/2% formic acid or Picaltal diluted in 10% water is added and the drum is operated for 1/2 hour.

If a small amount of eggplant liquid is required, it can be added to the acid deposition liquid at this point and the drum can be operated for another 1/2 hour. At this time, 1% sulfuric acid or formic acid pre-diluted in 10% water is added, and the drum is further operated for 1 hour. The final pH of the acid immersion liquid is 3 to 3.2 and the raw skin is sufficiently acid deposited, and its shrinkage temperature is 2 to 3 ° higher than the shrinkage temperature before the acid deposition. The product can be washed, splitting, watering and shaving to continue the process of the invention. However, since the shrinkage temperature after the subsequent pre-tanning does not determine the completion point of the pre-tanning, the shrinkage temperature after the pre-tanning for the purpose of the present invention is a reference, for example, even if the pretreatment is preceded or simultaneously with the pre-tanning. You have to understand.

Basically, there are two main forms of the prior art method for manufacturing leather (high-grade leather, upholstery, medical products, suede, etc.) from cowhide, as is currently practiced. In other words, even when the leather contains the lime used for hair loss, there are two methods for splitting after hair loss (lime splitting) or for splitting leather after chrome tanning (root splitting).

Each method has advantages and disadvantages, respectively. Lime fractionation provides about 2% more high tanning capacity and yield for warm cotton, as well as lighter and more uniform color for fine warm soft leather, aniline or semi-aniline leather, and splits when needed. Intermediate gives residual flexibility without chrome tanning. The split leather can then be planted or combined tanned to produce products suitable for use in shoe soles, belts, suades, medical products, and the like.

On the other hand, the processing speed of the splitting method is fast and simple, and thus, the leather is more taut as a quick operation.

The present invention combines the advantages of both lime splitting and blue splitting methods and uses a minimal amount of chrome tanning agents.

Particular preference is given to pretanning with a mixture of “HELATAN 9501” or “9502” series. The reaction between raw collagen and synthetic tannins with phenolic hydrosyl and carboxyl groups and the formation of crosslinks (formed by this or synthetic tannins) between collagen polypeptide chains improves the thermal stability and shrinkage temperature of the final chrome tanner. Contribute to. It is believed that much of the hydrophilic groups in raw collagen are converted to hydrophobic groups by the applied tanning process.

As known in the art, synthetic tanning agents (Syntan) are essentially sulfonated phenol formaldehyde-type condensates or carboxyl group-containing resins, all of which are very effective pretanning agents in the present invention.

As is well known, the penetration and binding of glutaraldehyde of various different types of synthetic tanning agents to collagen is influenced by temperature, concentration, proportion of chemicals and pH of the raw skin during pretanning operations.

According to the present invention, pretanning by synthetic tanning agents can be carried out at pH 7.5 to 8.5 after deliming, but good and rapid penetration is achieved at low pH such as 5.0 to 5.3 during acid deposition or at lower pH after acid deposition.

The effectiveness of the pretanning is determined as the shrinkage temperature after completing the pretanning. Shrinkage temperatures lower than about 170 ° F. do not indicate sufficient pretanning to be an excellent aid in either split or final tanning. On the other hand, shrinkage temperatures higher than about 185 ° F. after pre-tanning prevent the pre-tanning product from obtaining all of the desirable characteristics of chrome tanning leather. Tannin (plant) pretanning, aldehyde pretanning or pretanning by the compounds for aluminum or zirconium tanning are generally not as desirable as synthetic tannin pretanning, but the best results are mixed pretanning agents, preferably ＂Helatan＂ It is generally obtained from the mold mixture.

Many other modifications are possible in accordance with the present invention. Vinegar acid may be used instead of formic acid and sulfuric acid or hydrochloric acid may be used, but sulfuric acid and hydrochloric acid are not preferred as the only acidifying agent in the pretanning. Other synthetic tannins, such as those described in Example 1 of US Pat. No. 3,557,078, or in Chapter 21 of MaLaughlin-theis, Chemistry of Leather Manufacture (issued in 1945 by Rein-hold Publishing Corp.). Described or Thomas c. One may use the one described in Chapter 10 of Thorstensen's edition of Leather Leather Technology (published in 1969 by Reinhold Publishing Corp.). Eggplant treatment usually adds enough egg oil to keep the final leather at about 6 to about 15% by weight.

Representative methods for other hair loss and demineralization techniques can be found in the literature and in Wilson-Strather-Gierth, published by Julius Springer Publishing, 1930, Die Chemie der Leder Fabrikation, and Dr. It is described in the literature by Peter Van Vlimmeren. Such a treatment method is almost always used in leather production, but whether or not such a method is used is not related to the present invention except that it is possible to carry out the raw skin from the drum, and it can be carried out in the same treatment drum as the pre-tanning.

Compared with chemical change and continuous drum operation, the removal of such raw materials is inconvenient and costly operation, and the best way is to avoid this method. If you need to know the weight of raw hides after hair loss, you can use the "Hide Processor Machine" with a scale to measure the weight.

Disposal of the used chromium tanning solution is a problem in that it is generally not allowed to release the used liquid to rivers and sewers in an unlimited manner because it affects aquatic or groundwater.

In the present invention such emissions are reduced to a minimum without degrading the quality of the chrome treated leather produced.

The amount of chromium tanning agent used in accordance with the present invention is based on the weight after shaving of the raw hide to be chrome tanned and the weight after such shaving as described in each example is much less than the original raw hide weight. In addition, chrome tanning of silver does not require the same division of chrome tanning as is required in the standard blue splitting operation of the prior art, and vice versa. Reduced.

The tanning and splitting process of the present invention is particularly concerned with the tanning of cowhide and similar raw hides, which are made of high quality leather which is relatively thick and characterized by chrome tanning.

Chlorine and sheep leathers are not generally divided and thus cannot be applied to this process.

The quality of the chrome tanning leather of the present invention is the best because it combines the advantages of chrome tanning with the delicate, soft and light features of the prior art lime split.

Indeed, the physical properties of the chrome tanned leather of the present invention are better than those generally obtainable as prior art.

Therefore, the typical groove tear test of 2 1/2 to 3 ounces of chrome tanned leather of the present invention is a high value of about 20, which is generally 13 or more, whereas the groove tear value of a standard leather split leather is generally 13 Pretty less than

If the pretanning of the present invention is not carried out, the partially treated raw skin tends to be damaged by the shaving device even if it is sufficiently acidified, for example.

Therefore, in the pre-tanning process, the operation of loading or removing the tanning raw material into a drum or other processing device is minimized.

Acid deposition, which allows avoidance of various problems with subsequent splitting processes, is best performed at a pH of 3.5 or lower. In particular, the same pH of 4 or 5 can be effectively used if the raw material processing is not interrupted. In addition to simplifying the splitting process by making the partially treated hides at pH 3.5 better being completely acidic at pH 3, the raw hides are either before or after the splitting process, and therefore suitable for heat-resistance for interruptions such as remote transport. You are in a state. Acid deposition requires at least one hour of rotation at this pH level.

The spent chrome tanning liquor can be recycled to the chrome tanning process instead of the water used as a suspension.

Therefore, the amount of chromium tanning agent newly added can be reduced.

The total amount of waste chrome tanning which must be discarded in the case of carrying out the present invention is extremely small and sometimes becomes zero, such as when all of the used liquid is reused in the suspension for the new tanning of silver or splitting.

Claims (1)

Undivided raw skin is a tanning material that does not contain chromium in its original form, and is pre-tanned until its shrinkage temperature is about 170 to 185 ° F. The pre-tanned raw skin is divided into silver-coated intermediates. Shaving the intermediate and shaving the intermediate, and chrome tanning the shaved intermediate, yielding at least about 3% higher yield than that produced by the lime splitting method. Method for manufacturing chrome tanned silver leather.