Polysaccharide and/or polypeptide based graft polymers as synthetic tannins

Abstract

A graft polymer of polysaccharides or polypeptides or its respective derivatives, obtainable by free radical polymerization of A) a monomer selected from or a monomer mixture of (a) from 20 to 100% by weight of acrylic acid or methacrylic acid or of a mixture thereof or of the alkali metal, alkaline earth metal or ammonium salts thereof, (b) from 0 to 80% by weight of other monoethylenically unsaturated monomers which are copolymerizable with the monomers (a) and (c) from 0 to 5% by weight of monomers having at least 2 ethylenically unsaturated, nonconjugated double bonds in the molecule, in the presence of either B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidized hydrolytically degraded or oxidized enzymatically degraded polysaccharides, or such chemically modified degraded products, chemically modified mono-, oligo-or poly-saccharides or mixtures of the stated compounds and/or B2) polypeptides, their hydrolysates or enzymaticallydegraded and optionally chemically modified products or mixtures of the stated compounds in a weight ratio A: (B1 or B2) of from 1:99 to 18:82 or in a weight ratio A:(B1+B2) of from 60:40 to 1:99 and B1:B2 of from 97:3 to 3:97 used as tanning agents.

Claims

1. A tanning agent comprising a graft polymer obtained by free radical polymerization of: A) a monomer or a monomer mixture comprising: (a) 20 to 100% by weight of acrylic acid, or methacrylic sold, or alkali metal, alkaline earth metal, or ammonium salts of acrylic add, or alkali metal, alkaline earth metal, or ammonium salts of methacrylic acid, or a mixture thereof; (b) 0 to 80% by weight of other moncethylenically unsaturated monomers which are copolymerizable with the monomer (a); and (c) 0 to 5% by weight of monomers having at least 2 ethylenically unsaturated, nonconjugated double bonds in the molecule, in the presence of a mixture of both: B1) oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidized hydroiytically degraded or oxidized enzymatically degraded polysaccharides, or chemically modified degraded products, chemically modified mono-, oligo-or polysaccharides or mixtures of the stated compounds, wherein the polysaccharides have an average molecular weight of 500-10,000 Dalton, and B2) hydrolytically or enzymatically degraded polypeptides, or chemically modified polypeptides, or mixtures of the stated compounds, wherein the polypeptides have an average molecular weight greater than 1,500 Dalton, and having a weight ratio A:(B1+B2) of (1 to <45):(99 to >55), and a weight ratio of B1:B2 of 97:3 to 3:97.

2. The tanning agent according to claim 1, wherein: the polysaccharides are oxidatively, hydrolytically or enzymatically degraded polysaccharides having an average molecular weight of 500 to 5,000 Dalton; the polypeptides, hydrolytically or enzymatically degraded, and optionally chemically modified polypeptides have an average molecular weight greater than 5000; and a weight ratio of B1:B2 of 97:3 to 70:30, or 30:70 to 5:95.

3. The tanning agent according to claim 1, wherein the polysaccharides are hydrolyticaliy degraded starch having an average molecular weight of 3,000 to 8,000 Dalton.

4. The tanning agent according to claim 1, wherein the weight ratio A:(B1+B2) is (1 to 44.5):(99 to 55.5).

5. The tanning agent according to claim 1, wherein the weight ratio of A:(B1+B2) is (1 to 40):(99 to 60).

6. Process for the manufacturing of graft polymers according to claim 1 by free radical induced co-polymerization, the process comprising adding the components of the monomers of A) to B1) and B2) in an inert solvent at a temperature of 40 to 150° C. in the presence of a free radical-forming initiator, wherein less than 10% of the free radical forming initiator is with the component B1) and B2) before the addition of the monomers A), and a remaining portion of the radical-forming initiator is added together with the monomers of A).

7. A process for the self-tanning, pretanning or assist tanning of leather pelts or skin pelts, or for the retanning of leather or skins, the process comprising treating leather pelts or skin pelts with tanning agents of graft polymers according to claim 1.

8. Leather, self-tanned, pretanned, assisted tanned or returned, with a tanning agent according to claim 1.

9. A tanning agent comprising a graft polymer obtained by free radical polymerization of: A) a monomer or a monomer mixture comprising: (a) 20 to 100% by weight of acrylic acid, or methacrylic acid, or alkali metal, alkaline earth metal, or ammonium salts of acrylic acid, or alkali metal, alkaline earth metal, or ammonium salts of methacrylic acid, or a mixture thereof; in the presence of a mixture of both: B1) oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidized hydrolytically degraded or oxidized enzymatically degraded polysaccharides, or chemically modified degraded products, chemically modified mono-, oligo-or polysaccharides or mixtures of the stated compounds, and B2) hydrolytically or enzymatically degraded polypeptides, or chemically modified polypeptides, or mixtures of the stated compounds, wherein: a weight ratio A:(B1+B2) is (1 to 60):(99 to 40), and a weight ratio of B1:B2 is (97-3):(3-97).

10. The tanning agent according to claim 9, wherein: the weight ratio of B1:B2 is (97-70):(3-30); and the weight ratio A:(B1+B2) is (60-40):(40-60) and (20-3):(80-97).

11. The tanning agent according to claim 10, wherein: B1 is selected from starch hydrolysates with molecular weights of 500-5000; and B2 is selected from polypeptides with an average molecular weight higher than 3000.

12. The tanning agent according to claim 9, wherein: the weight ratio of B1;B2 is (30-5):(70-95); and the weight ratio A:(B1+B2) is (60-40):(40-80) and (20-3):(80-97).

13. The tanning agent according to claim 12, wherein: B1 is selected from starch hydrolysates with molecular weights of 3000-10000; and B2 is selected from polypeptides with an average molecular weight higher than 3000.

Description

EXAMPLES

(1) For all the chemical synthesis, glass reactor with heating/cooling capacity has been used. The reactor was equipped with stirrer, a reflux condenser, thermometer, nitrogen in-let and feed in-lets. All raw materials were weight to accuracy of +/−1%. Continuous addition of reagents was effected using pumps. All the leather making trial was carried out using rotating drum in usual manner.

Example 1

(2) 400 grams of 30% by weight (in water) starch hydrolysate with average molecular weight 2400 gram/mole was introduced into 1 liter reactor. After purging for 30 minutes with nitrogen, 3 grams of ammonium cerium nitrate (dissolved in 30 ml of 1 n nitric acid) was introduced. The content of the react was heated to 30° C. under stirring for 1 hour. 16 grams of acrylic acid and 30 grams of distilled water were metered into the reactor over 6 hours (uniformly) at 30° C. under stirring. Then 0.1 grams of sodium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was heated to 90-92° C. under stirring, and the content of the reactor was then allowed to react for 2 hours. At the end of reaction, the content of the reactor was cooled to 40° C. and 15 grams of 50% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 45° C. The final product was obtained by allowing the reactor to cool to room temperature under stirring.

Example 2

(3) 400 grams of 40 by weight % (in water) starch hydrolysate with average molecular weight 3000 g/mole was introduced into I liter reactor. The content of the react was heated to 88-92° C. under stirring with nitrogen purging, 1.5 grams ammonium persulphate dissolved in 10 ml of distilled water was added and 5 minutes later 15.5 grams of acrylic acid and were metered into the reactor over 4 hours (uniformly). After curing for 1 hour, 0.02 grams of ammonium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was kept at 88-92° C. under stirring, and the content of the reactor was then allowed to react for 1 further hour. At the end of reaction, the content of the reactor was cooled to 40° C. and 30% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 60° C. until pH reaches 5-6. The final product was obtained by allowing the reactor to cool to room temperature under stirring and biocides were added and mixed well.

Example 3

(4) 400 grams of 38% by weight (in water) protein hydrolysate from animal source with average molecular weight 7400 g/mole was introduced into 1 liter reactor. The content of the react was heated to 88-92° C. under stirring with nitrogen purging. 1.35 grams ammonium persulphate dissolved in 10 ml of distilled water was added and 5 minutes later 14.8 grams of acrylic acid and were metered into the reactor over 4 hours (uniformly). After curing for 1 hour, 0.02 grams of ammonium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was kept at 88-92° C. under stirring, and the content of the reactor was then allowed to react for 1 further hour. At the end of reaction, the content of the reactor was cooled to 40° C. and 30% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 60° C. until pH reaches 5-6. The final product was obtained by allowing the reactor to cool to room temperature under stirring and biocides were added and mixed well.

Example 4

(5) 300 grams of 40% by weight (in water) protein hydrolysate with average molecular weight 3100 gram/mole and 150 grams of 40% by weight (in water) starch hydrolysate with average molecular weight 3300 g/mole was introduced into 1 liter reactor. The content of the react was heated to 88-92° C. under stirring with nitrogen purging. 1.5 grams ammonium persulphate dissolved in 10 ml of distilled water was added and 5 minutes later 17 grams of acrylic acid and were metered into the reactor over 2 hours (uniformly). After curing for 1 hour, 0.05 grams of ammonium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was kept at 88-92° C. under stirring, and the content of the reactor was then allowed to react for 1 further hour. At the end of reaction, the content of the reactor was cooled to 40° C. and 30% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 60° C. until pH reaches 5-6. The final product was obtained by allowing the reactor to cool to room temperature under stirring and biocides were added and mixed well.

(6) The compound powder product: 170 grams of kaolin and 180 grams of sodium lignosulphonate and 300 nil of water was mixed well with the above product. The powder product was obtained by spray drying of the mixture.

Example 5

(7) 15 grams protein from vegetable source and 400 grams of 35% by weight (in water) starch hydrolysate with average molecular weight 3000 g/mole was introduced into 1 liter reactor. The content of the react was heated to 88-92° C. under stirring with nitrogen purging. 1.5 grams ammonium persulphate dissolved in 10 ml of distilled water was added and 5 minutes later 14.8 grams of acrylic acid and were metered into the reactor over 4 hours (uniformly). After curing for 1 hour, 0.02 grams of ammonium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was kept at 88-92° C. under stirring, and the content of the reactor was then allowed to react for I further hour. At the end of reaction, the content of the reactor was cooled to 40° C. and 30% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 60° C. until pH reaches 5-6. The final product was obtained by allowing the reactor to cool to room temperature under stirring and biocides were added and mixed well.

Example 6

(8) 300 grams of 20% aqueous solution (by weight) of starch hydrolysate with average molecular weight 1200-1400 gram/mol and 6 grams native protein from vegetable source was introduced into 1 liter reactor. The content of the react was heated to 88-92° C. under stirring with nitrogen purging. 60 grams of acrylic acid and 2.25 grams sodium persulphate dissolved in 20 ml of distilled water were metered into the reactor over 3 hours (uniformly). After curing for 1 hour, 0.05 grams of sodium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was kept at 88-92° C. under stirring, and the content of the reactor was then allowed to react for I further hour. At the end of reaction, the content of the reactor was cooled to 40° C. and 30% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 60° C. until pH reaches 6-7. The final product was obtained by allowing the reactor to cool to room temperature under stirring and biocides were added and mixed well.

Example 7

(9) 300 grams of 25% (W/W in water) protein hydrolysate with average molecular weight 4200 gram/mole and 15 grams native starch from vegetable source was introduced into I liter reactor. The content of the react was heated to 88-92° C. under stirring with nitrogen purging. 72 grams of acrylic acid and 2,5 grams sodium persulphate dissolved in 40 ml of distilled water were metered into the reactor over 3 hours (uniformly). After curing for 1 hour, 0.05 grams of sodium persulphate dissolved in 2 ml of distilled water was added into the reactor and the content of the reactor was kept at 88-92° C. under stirring, and the content of the reactor was then allowed to react for 1 further hour. At the end of reaction, the content of the reactor was cooled to 40° C. and 30% sodium hydroxide solution was added slowly under stirring making sure the temperature in reactor below 60° C. until pH reaches 6-7. The final product was obtained by allowing the reactor to cool to room temperature under stirring and suitable biocides were added and mixed well.

COMPARATIVE EXAMPLES

(10) Compare sample 1 was made following the example 5 of U.S. Pat. No. 5,714,560 (protein core and about 60% acrylic acid).

(11) Compare sample 2 was made following the example 1 of U.S. Pat. No. 5,425,784 (sugar core and about 40% acrylic acid and 14% maleic anhydride).

(12) Compare sample 3 was made by a physical mixture of comparison sample 1 and comparison sample 2.

(13) Compare sample 4 is a commercial condensation product of a sulfonated phenol and formaldehyde.

(14) Application Example 1

(15) A bovine wet blue, shaved to 1.6 mm, was trimed so that the official test part was left. The piece was divided into four parts in middle and along backline to give a fair comparison. After rinse in a conventional manner, the wet blue was neutralised to pH5.5-5.7 in 100% liquor with a mixture of sodium formate and sodium carbonate. After drain and rinsing with water at 45° C., 100% water at 45° C. was added, 1% of brown dye was added. After running for 25 minutes, 3% of products of the respective tanning agents (present invention vs. comparison, see table) (at solid base) was added after mixing with 15% of water, The retanning time was 50 minutes. The leather was then fatliquored with 5% commercial fatliquor for 60 minutes and acidification to pH 3.6-3.8 were done in a conventional way using commercially available products. The drying and subsequent mechanical operations were also carried in a conventional manner.

(16) The leather was assessed subjectively and the results show that agent from this invention is different and superior to the comparative samples.

(17) Assessment Results

(18) (in 1-5 arbitrary scale, 1=poor, 2=fair, 3=good, 4=very good, and 5=exceptional)

(19) TABLE-US-00001 Example 6 of this Comparative Comparative Comparative Items tested invention sample 1 sample 2 sample 3 Surface dyeing 4 3 2.5 2 shade Fullness 4 2 3.5 2 Softness 3 2 2 2 Grain tightening 4 4 2 2 Aesthetical Full and Harsh grain Reasonably Poor handle assessment nice and full and handle poor handle acceptable handle

(20) Conclusion: The present invention shows with respect to the combination of polysaccharide and polypeptide an unexpected improvement over the prior art tanning agents with pure saccharide or polypeptide based graft polymers respectively and even a better result over the physical mixture of both. Examples 4, 5 and 7 show as well as good results.

Application Example 2

(21) A bovine wet blue, shaved to 1.6 mm, was trimed so that the official test part was left. The piece was divided into four parts in middle and along backline to give a fair comparison. After rinse in a conventional manner, the wet blue was neutralised to pH 5.5-5.7 in 100% liquor with a mixture of sodium formate and sodium carbonate. After drain and rinsing with water at 45° C., 100% water at 45° C. was added, 1% of brown dye was added. After running for 25 minutes, 8% of products (at solid base on wetblue eight) (present invention vs. comparison, see table) was added after mixing with 15% of water. The retanning time was 50 minutes. The leather was then fatliquored with 5% commercial fatliquor for 60 minutes and acidification to pH 3.6-3.8 were done in a conventional way using commercially available products. The drying and subsequent mechanical operations were also carried in a conventional manner.

(22) The leather was assessed subjectively and the results show that agent from this invention behaves like a traditional syntan while compare sample 1 and 2 still behave like a acrylic resin.

(23) Assessment Results

(24) (in 1-5 arbitrary scale, 1=poor, 2=fair,3=good, 4=very good, and 5=exceptional)

(25) TABLE-US-00002 Example 5 Example 2 of this Comparative of this Comparative Items invention sample 2 invention sample 4 Surface dyeing 4 2 3 3 shade fullness 3.5 2.5 4 4 softness 3.5 2.5 3.5 3 Grain tightening 3 2 3 2.5 Aesthetical Full, supple Rubbery Full, Full and assessment leather “synthetic” supple supple with type of leather leather pleasing handle with handle pleasing handle

(26) Conclusion: The present invention shows that when the acrylic portion (A component) in the graft polymer is low, the graft polymer performs similar to conventional phneolic based syntan. Here the combined protein-polysaccharide approach also show advantages. In addition an improvement can be shown over comparison examples with higher acrylic amounts (see Example 5 vs. comparison example 2; Example 2 vs. comparison example 2).

Application Example 3

(27) A bovine wet blue, shaved to 1.6 mm, was trimed so that the official test part was left. The piece was divided into four parts in middle and along backline to give a fair comparison. After rinse in a conventional manner, the wet blue was neutralised to p1-15.5-5.7 in 100% liquor with a mixture of sodium formate and sodium carbonate. After drain and rinsing with water at 45° C., 100% water at 45° C. was added, 1% of brown dye was added. After running for 25 minutes, 8% of products (at solid base) (present invention vs. comparison, see table) was added after mixing with 15% of water. The retanning time was 50 minutes. The leather was then fatliquored with 5% commercial fatliquor for 60 minutes and acidification to pH 3.6-3.8 were done in a conventional way using commercially available products. The drying and subsequent mechanical operations were also carried in a conventional manner.

(28) The leather was assessed subjectively and the results show that agent from this invention behaves like a traditional syntan while compare sample 1 and 2 still behave like a acrylic resin.

(29) Assessment Results

(30) (in 1-5 arbitrary scale, 1=poor, 2=fair,3=good, 4=very good, and 5=exceptional)

(31) TABLE-US-00003 Example 4 Example 3 of this Comparative of this Comparative Items invention sample 1 invention sample 4 Surface dyeing 3.5 3 4 3 shade fullness 3.5 2 3 4 softness 3 1.5 2.5 3 Grain tightening 3 3 4 2.5 Aesthetical Full, Papery and Full, Full and assessment supple rubbery supple supple leather leather with leather with pleasing pleasing handle handle

(32) Conclusion: The present invention shows that when the acrylic portion (A component) in the graft polymer is low, the graft polymer performs similar to conventional syntan. Here the combined protein-polysaccharide approach also show advantages. In addition an improvement can be shown over comparison examples with higher acrylic amounts (see Example 4 vs. comparison example 1; Example 3 vs. comparison example 1).

Application Example 4

(33) A bovine wet blue, shaved to 1.6 mm, was divided into two mirrored parts along backline to give a fair comparison. The two pieces was processed in twinned drums to reduce possible variations and the following process was used. After rinse in a conventional manner, the wet blue was neutralised to pH5.0-5.2 in 100% liquor with a mixture of sodium formate and sodium carbonate. After drain and rinsing with water at 45° C., 100% water at 45° C. was added, for sample 6% of product from example 6 was used for retanning while the retanning of reference piece was effected by using 6% medium molecular weight poly acrylic acid, sodium salt (30% solid content) (commercial product). The retanning time was 90 minutes. After drain and rinse with water at 50° C., dyeing by 3% commercial leather dye, fatliquoring with 6% commercial fatliquor and acidification to pH 3.6-3.8 were done in a conventional way using commercially available products. The mechanical operation and drying were also carried in a conventional manner.

(34) The results shown that compared with reference, leather made by using our sample is tighter, fuller and mellower.

(35) Examples 1-5 and 7 show as well as good results.

Application Example 5

(36) The limed pelt was delimed and bated by using traditional procedure (ammonium Deliming and mixed bating agent) and washed and drained well using a standard rotating tanning drum. 40% of water (based on the weight of limed pelt, all the percentage weights in this example are the same based on the limed pelt weight) was added followed by 8% of common salt (sodium chloride). After rotating for 5 minutes to dissolve salt, 0.5% of formic acid (diluted with water 1:5) and 0.9% of sulphuric acid (dilute in water 1:10) was added. Run for 120 minutes and pH was between 2.9-3.1. 4% of product made in example 3 was added and the drum was rotated for further 90 minutes. Then 6.0% of chrome tanning agent (typically 25% chrome oxide and basicity 33%) was added and drum was rotated for 120 minutes. 0.45% of finely powdered magnesium oxide was added and drum was rotated for further 9 hours. The final pH was about 3.9 and final temperature was about 42° C. After draining the float the tanned leather was briefly rinsed with 200% cold water.

(37) As reference, the same process was run without sample from example 3.

(38) The result shows that the addition of product from example 3 has increased chrome oxide up-take by leather and better handle and more uniform wet blue was obtained. Examples 1, 2 and 4 to 7 show as well as good results.

Application Example 6

(39) A bovine wet blue, shaved to 1.6 mm, was divided into two mirrored parts along backline to give a fair comparison. The two pieces was processed in twinned drums to reduce possible variations and the following process was used. After rinse in a conventional manner, the wet blue was neutralised to pH 5.0-5.2 in 100% liquor with a mixture of sodium formate and sodium carbonate. After drain and rinsing with water at 45° C., 100% water at 45° C. was added, for sample 4% of product from example 4 and 4% of product from sample 5 was used for retanning while the retanning of reference piece was effected by using 6% spray-dried PSA-urea-phenol-formaldehyde condensate (commercial product). The retanning time was 90 minutes. After drain and rinse with water at 50° C., dyeing by 3% commercial leather dye, fatliquoring with 6% commercial fatliquor and acidification to pH 3.6-3.8 were done in a conventional way using commercially available products. The mechanical operation and drying were also carried in a conventional manner.

(40) The assessment of resultant leather showed that leather retanned using our environmental friendly synthetic tanning agent from examples 4 and 5 respectively has better surface dyeing shade, more level and the handle is comparable to those of leather retanned using traditional synthetic tanning agent. This example also highlights another advantage of this invention—the products of this invention may contain less salt (i.e. virtually salt free for low portion A products) therefore it is more effective than the conventional syntan on solid base. Here 8% total of 45% solid content liquid will give a total solid about 4% and it is as effective as 6% of solid conventional syntan.

Application Example 7

(41) A bovine wet blue, shaved to 1.6 mm, was used. After rinse in a conventional manner, the wet blue was neutralised to pH 5.0-5.2 in 100% liquor with 4.5% of example 3, 2% commercial neutralising agent and a mixture sodium acetate and sodium bicarbonate. After drain and rinsing with water at 35° C., 60% water at 35° C. was added, 3% of a commercial polymeric retanning agent, 4% of example 6 and 2% commercial penetrating fatliquor (all diluted in warm water 1:3) were added. After running for 20 minutes 3% of leather dyestuff and 3% commercial amino-resin as added. After running for 20 minutes, 12% of example 2 was added. After running for another 20minutes, 1% leather top dyestuff and 2% fatliquor was added. After running for 60 minutes, the system as acidified to pH 4-4.2 by using formic acid. After drain and rinse with water at 55° C., fatliquoring with 10% commercial fatliquor and acidification to pH 3.6-3.8 were done in a conventional way using commercially available products. The mechanical operation and drying were also carried in a conventional manner.

(42) The assessment of resultant leather showed that leather retanned using our environmental friendly synthetic tanning agents in combination with currently available commercial products has full dye penetration and deep and level surface dyeing shade. The tighten grain, supple bady and appealing handle make it suitable for the specified commercial requirements with desired edges.

Comparative Example 5

(43) Example 2 of US2008/0229511 (sodium alginate having an average molecular weight of about 100.000 and protein hydrolysate core and about 88.9% acrylic acid) was repeated and tested in the application examples 8.

Application Example 8

(44) A bovine wet blue, shaved to 1.5 mm, was trimmed so that the official test part was left. The piece was divided into four parts in middle and along backline to give a fair comparison. After rinse in a conventional manner, the wet blue was neutralised to pH5.0-5.4 in 100% liquor with a mixture of sodium formate and sodium carbonate. After drain and rinsing with water at 45° C., 100% water at 45° C. was added, 3% of products of comparative example 5 (at solid base on wetblue weight) were added after mixing with 15% of water. After running for 60 minutes, 2% of black leather dye was added. The dyeing time was 60 minutes. The leather was then fatliquored with 5% commercial fatliquor for 60 minutes and acidification to pH 3.4-3.8 was done in a conventional way using commercially available products. The drying and subsequent mechanical operations were also carried in a conventional manner.

(45) The leather was assessed subjectively and the results show that agents from this invention produced satisfactory leather while the comparative sample 5 formed coating-like surface layer and blocked the penetration/fixation of dyestuff and fatliquor resulting in very poor leather.

(46) Assessment Results

(47) (in 1-5 arbitrary scale, 1=poor, 2=fair,3=good, 4=very good, and 5=exceptional)

(48) TABLE-US-00004 Example 4 Additional of this Comparative Example 6 of this Items invention sample 5 invention Surface dyeing 5 1 4 shade fullness 4 4 4 softness 4 1 3 Grain tightening 3 2 4 Aesthetical Soft leather Hard and dead Full, supple leather assessment with pleasing leather with very with good handle handle light surface shade.