CN113278741B - Preparation method of thin undenatured collagen sheet material - Google Patents
Preparation method of thin undenatured collagen sheet material Download PDFInfo
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- CN113278741B CN113278741B CN202110551039.2A CN202110551039A CN113278741B CN 113278741 B CN113278741 B CN 113278741B CN 202110551039 A CN202110551039 A CN 202110551039A CN 113278741 B CN113278741 B CN 113278741B
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- 102000008186 Collagen Human genes 0.000 title claims abstract description 65
- 108010035532 Collagen Proteins 0.000 title claims abstract description 65
- 229920001436 collagen Polymers 0.000 title claims abstract description 65
- 239000000463 material Substances 0.000 title claims abstract description 45
- 238000002360 preparation method Methods 0.000 title claims abstract description 6
- 239000010985 leather Substances 0.000 claims abstract description 55
- 238000000034 method Methods 0.000 claims abstract description 41
- 239000012024 dehydrating agents Substances 0.000 claims abstract description 36
- 238000012545 processing Methods 0.000 claims abstract description 28
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 20
- 230000008569 process Effects 0.000 claims abstract description 19
- 238000002791 soaking Methods 0.000 claims abstract description 11
- 230000018044 dehydration Effects 0.000 claims abstract description 8
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 30
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 27
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 15
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 15
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 11
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 8
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 8
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 8
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 8
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims description 8
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 8
- 241001494479 Pecora Species 0.000 claims description 7
- 239000004202 carbamide Substances 0.000 claims description 6
- 241000283707 Capra Species 0.000 claims description 5
- ZNQVEEAIQZEUHB-UHFFFAOYSA-N 2-ethoxyethanol Chemical compound CCOCCO ZNQVEEAIQZEUHB-UHFFFAOYSA-N 0.000 claims description 4
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 4
- 235000019270 ammonium chloride Nutrition 0.000 claims description 4
- 235000019253 formic acid Nutrition 0.000 claims description 4
- 239000004310 lactic acid Substances 0.000 claims description 4
- 235000014655 lactic acid Nutrition 0.000 claims description 4
- ZNNZYHKDIALBAK-UHFFFAOYSA-M potassium thiocyanate Chemical compound [K+].[S-]C#N ZNNZYHKDIALBAK-UHFFFAOYSA-M 0.000 claims description 4
- 229940116357 potassium thiocyanate Drugs 0.000 claims description 4
- 206010042674 Swelling Diseases 0.000 claims 4
- 230000008961 swelling Effects 0.000 claims 4
- 230000035617 depilation Effects 0.000 claims 1
- 239000000835 fiber Substances 0.000 abstract description 12
- 238000004925 denaturation Methods 0.000 abstract description 3
- 230000036425 denaturation Effects 0.000 abstract description 3
- 235000013305 food Nutrition 0.000 abstract description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 208000005156 Dehydration Diseases 0.000 description 6
- 238000001125 extrusion Methods 0.000 description 6
- 241000283690 Bos taurus Species 0.000 description 5
- 239000012528 membrane Substances 0.000 description 5
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 206010067868 Skin mass Diseases 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 206010048038 Wound infection Diseases 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000007385 chemical modification Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 229910052979 sodium sulfide Inorganic materials 0.000 description 1
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 210000004243 sweat Anatomy 0.000 description 1
- 238000009941 weaving Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14B—MECHANICAL TREATMENT OR PROCESSING OF SKINS, HIDES OR LEATHER IN GENERAL; PELT-SHEARING MACHINES; INTESTINE-SPLITTING MACHINES
- C14B1/00—Manufacture of leather; Machines or devices therefor
- C14B1/58—Drying
-
- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C11/00—Surface finishing of leather
-
- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C9/00—Impregnating leather for preserving, waterproofing, making resistant to heat or similar purposes
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Treatment And Processing Of Natural Fur Or Leather (AREA)
Abstract
A preparation method of thin type undenatured skin collagen sheet material is characterized in that the thickness of a naked skin after unhairing and liming is adjusted by a skin splitting machine, then the naked skin is delimed by a deliming method of conventional leather processing, and then is treated by an expanding agent until the naked skin is uniformly expanded to be semitransparent; after the expansion is finished, the dehydrating agent is replaced after soaking for at least 30min, and the dehydrating agent is soaked in the dehydrating agent for 3-6 times in the dehydrating process; after dehydration, the sheet material is extruded by a through wringing machine and then is shaved by a shaving machine to obtain the thin type collagen sheet material with the thickness of 0.3-0.5 mm. The method uses a dehydrating agent to dehydrate in the expansion state of the naked skin, so that collagen fiber bundles are dispersed and maintain a porous structure, and uses the characteristic of easy volatilization of the dehydrating agent to prevent the thermal denaturation of the skin in the shaving process, thereby obtaining the untanned thin skin collagen sheet material. The product retains the natural structure of collagen in the leather block, and can be used in the fields of leather making, biomedicine, food and the like.
Description
Technical Field
The invention belongs to the technical field of leather chemistry and engineering and film processing, and particularly relates to a preparation method of a thin leather collagen sheet material which keeps a leather collagen triple helix structure and is not tanned by a tanning agent.
Background
In the processing process of leather making and sheet collagen, the thickness adjustment directly influences the application range of products and also directly influences the economic benefits of production enterprises. The thickness adjustment in the processing process of the prior leather making and sheet collagen materials mainly comprises two operations of peeling and shaving, wherein the peeling is to cut the leather into required thickness by utilizing a sharp band knife and obtain a plurality of layers of sheet materials at the same time, the shaving is to cut the leather by utilizing a sharp spiral knife rod to obtain a layer of sheet materials with specific thickness, and the redundant part is discarded in a scrap mode. The multilayer sheet materials obtained from the sheet leather can be processed and sold in different degrees, scraps generated by shaving are difficult to generate economic benefits, the processing precision of the sheet leather is limited, a thin sheet material of the skin collagen cannot be obtained, although the shaving processing precision is high, the product thickness can be low, but high temperature can be generated in the shaving process, in order to prevent the scorching and the collagen denaturation, the sheet leather is usually required to be tanned, so that the sheet leather can be shaved after the sheet leather has higher shrinkage temperature to obtain the thin sheet material of the skin collagen, and the sheet leather after being treated by pickling or rolling nitrate can be shaved, but the product thickness is thick, and the thin degree which can be achieved by shaving the tanned sheet leather is difficult to achieve.
In order to prepare thin undenatured skin collagen sheet materials for being used as processing materials of products such as medical dressings, ultrathin leathers, filter membranes and the like, the development of a processing method which can mechanically process unttanned skins to obtain thin sheet materials is urgently needed.
Disclosure of Invention
The inventors have conducted intensive studies on the disclosed tanning chemistry, leather processing machinery and collagen modification techniques in order to prepare an untanned thin skin collagen sheet material. The method of splitting and shaving can be adopted to thin the leather, the shaving can achieve high precision and good uniformity, but the fiber bundle of the leather before shaving needs to be dehydrated and has good thermal stability, otherwise the collagen is denatured by the shaving knife roller and the high temperature generated by the strong cutting of the leather, so the leather after the tanning of the shaved object at present.
The hide is woven from collagen bundles through a complex three-dimensional structure. Because the collagen has good hydrophilicity and water absorbability and the complex spatial structure of the collagen bundles, the sheet-shaped collagen processed by the leather has good air permeability, water vapor permeability and moisture absorption and sweat releasing performance, and the traditional application is used for processing various types of leather products. At present, sheet collagen processed from leathers is no longer limited in the leather making field, and is increasingly applied in the fields of medical dressings and various membrane materials.
In the traditional leather making field, leathers must be tanned, so the thickness can be adjusted by shaving operation, but with the improvement of the living quality of people, the demand on ultrathin leathers, especially ultrathin clothing leathers is more and more increased, and the thickness of the traditional clothing leathers is 0.6-1.0mm, which is difficult to meet the requirements of people. The thickness of the leather is too large, the permeation rate of gas or liquid is too slow when the leather is used for medical dressing and membrane materials for filtration, and the established effect is difficult to realize, so that the thickness of the finished product is required to be thinner, and the flaky collagen processed by the leather cannot be tanned and then shaved as the conventional leather making process due to special purposes. In order to prepare ultrathin leather, medical dressing and filter membrane, a processing method of thin non-tanned thin undenatured skin collagen sheet material needs to be developed.
The processing of the ultrathin skin collagen sheet material needs to consider two problems, namely the processing characteristics of processing machinery and the histological characteristics of the skin. The splitting machine is simple in structure and easy to operate, and can split a skin into a plurality of layers, but the thickness of the split layer is about 1.0mm at the thinnest, and the thickness is not uniform enough; the shaving machine has a complex structure and high operating technology content, the peel dregs generated by cutting generally have no value, but the thickness of the shaved peel can reach 0.3mm and is very uniform. The tighter the weaving of the hide fiber is, the greater the shaving resistance is, when shaving from a certain thickness to a specified thickness, the phenomenon that the thickness is increased by 20-50% compared with that in shaving is easy to occur because the extrusion of the knife roller between the fibers is heavy and the hide fiber is placed for a period of time after shaving. In order to prevent the thickness of the processed product from being increased after shaving and during the placement, the collagen fiber bundles in the skin must be sufficiently loosened.
High temperature that the in-process of shaving produced can make skin collagen denaturalization, if the skin soaks through volatile organic solvent, the heat that produces when shaving can be taken away in volatilizing of solvent in the skin, can avoid skin collagen denaturation. Meanwhile, some special solvents have good dehydration effect, can disperse and shape the collagen fiber bundles to generate the effect similar to tanning, but can not denature collagen. Therefore, the inventor uses the solvent with dehydration function to soak the pelts, removes the water in the pelts and shapes the collagen fiber bundles, and can realize the purpose of shaving the unttanned hide without denaturing the collagen. The leather blocks soaked by the solvent are evenly shaved and then put into water, and the collagen has good hydrophilicity, so that the collagen can quickly absorb water and restore to a leather state, and the leather can be tanned to produce ultra-thin leather which can be used as a medical dressing or a film material through other processing and chemical modification.
When the pelts are in the expanded state, the collagen bundles are filled with water, the density of collagen in the skin mass is low, and if the water in the skin mass is removed at this time, the collagen sheet material with large porosity can be obtained. Therefore, the inventor selects firstly to carry out splitting operation on the pelts after unhairing and liming, obtains the thinness which can be achieved under the working condition according to the limitations of the pelts and the processing machinery, then carries out deliming operation to remove lime and sodium sulfide in the pelts, then uses the expanding agent which is easy to dissolve in water to expand the pelts again, reduces the density of collagen fiber bundles in the pelts, and finally uses the dehydrating agent to dehydrate, thus obtaining the collagen fiber sheet material with larger porosity. When the leather is used for tanning, the finished leather density can be reduced, and the water and air permeability can be improved; when the medical dressing is used for medical dressing, the dressing can be thinner and more breathable, and wound infection is prevented; when it is used for a filtration membrane, the filtration efficiency can be improved.
Based on the research, the inventor provides a preparation method of a thin undenatured skin collagen sheet material, which is characterized in that after the thickness of pelts subjected to unhairing and liming is adjusted to 0.8-1.4mm by a skin splitting machine, the pH value of the pelts is adjusted to 7.5-8.5 by a deliming agent according to a deliming method of conventional leather processing; expanding the delimed pelts by using an expanding agent until the pelts are uniformly expanded to be semitransparent; soaking the expanded pelts in a dehydrating agent with the weight of 300 percent of the weight of the pelts for at least 30min, and then replacing the dehydrating agent, wherein the pelts are soaked in the dehydrating agent for 3-6 times in the dehydrating process; after the pelts are dehydrated, a through wringing machine is adopted to squeeze and remove the redundant dehydrating agent, and then a shaving machine is used for shaving to obtain the thin type collagen sheet material with the thickness of 0.3-0.5 mm.
Wherein the pelts after unhairing and liming are any one of goat skins, sheep skins, cow head skins or pig skins; the deliming agent is one or two of ammonium sulfate, ammonium chloride, formic acid, lactic acid and ammonia-free deliming agent; the expanding agent is any one of sodium hydroxide, potassium hydroxide, urea or potassium thiocyanate, and the using amount of the expanding agent is 0.2-2.0% of the weight of the naked hide after the thickness of the naked hide is adjusted by the flaking machine; adding the expanding agent for 1-3 times, wherein the interval of each time is 30-120min, and the expanding treatment time is 2-6 h; the dehydrating agent is any one of methanol, ethanol, acetone or ethylene glycol ethyl ether; the total dehydration time is 4-12h, and the end point of the treatment is that the moisture content (calculated by mass fraction) in the dehydrating agent is less than 3.0 percent. (ii) a The pressure of the through wringing machine is 0.4-0.7MPa, and the running speed is 3-8 m/min.
The second-layer leather of the cow can be scattered into fragments when the thickness is very thin due to thick and loose fiber bundles, so that only the first layer of the cow leather can be used for processing thin undenatured leather collagen sheet materials, the goat leather and the sheep leather are very thin due to the thickness, the second-layer leather cannot be obtained in the conventional sheet processing, the pigskin fiber is knitted compactly, and the first layer and the second layer can be made of undenatured leather collagen sheet materials. The ash content of the pelts after unhairing and liming can be reduced through deliming, so that the pelts are favorable for re-expansion and dehydrating agent dehydration in the later period, and meanwhile, the lower ash content is also favorable for improving the thickness uniformity of the obtained finished product. The excessive dehydrating agent in the leather can be removed through the wringing machine, and the precision of the shaving processing is ensured.
The method provided by the invention has the following advantages in the process of preparing the undenatured collagen sheet material: 1. the method can be realized by adopting common equipment and mechanical operation of a tanning enterprise, no special equipment is needed, and the used reagent is a conventional chemical material, so that the practicability is high; 2. the obtained skin collagen sheet material is not modified by a tanning agent, and simultaneously retains the natural structure of collagen in the leather block, and the product can be used for tanning processing and can also be used in the fields of biological medicines, foods and the like; 3. the whole animal skin can be processed to obtain a skin collagen sheet material with a larger area, and the product has wider application; 4. the thickness of the obtained collagen skin sheet material is only 0.3-0.5mm, and the thickness of the product is uniform.
Detailed Description
The following examples are given to illustrate the present invention in more detail, and it should be noted that the following examples are not to be construed as limiting the scope of the present invention, and that the insubstantial modifications and variations of the present invention can be made by those skilled in the art based on the above disclosure.
Example 1
Adjusting the thickness of the dehaired and limitted cow head skin to 0.8mm by a skin splitting machine, and adjusting the pH value of the naked skin to 7.5 by ammonium sulfate and ammonium chloride according to a deliming method of conventional leather processing; after the thickness of the pelts is adjusted by a splitting machine, potassium hydroxide which is 0.2 percent of the weight of the pelts is added at one time, and then expansion treatment is carried out for 2 hours until the pelts are uniformly expanded to be semitransparent; soaking the expanded pelts in 300 wt% of ethylene glycol ether for 60min, and then replacing the dehydrating agent, wherein the pelts are soaked in the ethylene glycol ether for 4 times in the dehydration treatment process until the moisture content (calculated by mass fraction) in the dehydrating agent is 3.0%; after the pelts are dehydrated, redundant ethylene glycol ethyl ether is removed by adopting a through wringing machine for squeezing, the pressure of the through wringing machine is 0.7MPa, and the running speed is 8 m/min. Then the thin undenatured collagen flake material with the thickness of 0.4mm can be obtained after being evenly shaved by a shaving machine.
Example 2
Adjusting the thickness of the goat skin after unhairing and liming to 1.4mm by using a skin splitting machine, and adjusting the pH value of the naked skin to 8.5 by using an ammonia-free deliming agent according to a deliming method of conventional leather processing; adding sodium hydroxide with the weight of 0.4% of that of the pelts into the pelts after the thickness of the pelts is adjusted by a splitting machine for 2 times at intervals of 120min, and performing expansion treatment for 4h after the sodium hydroxide is added until the pelts are uniformly expanded to be semitransparent; soaking the expanded pelts in acetone with the weight of 300% of the weight of the pelts for 120min, and then replacing a dehydrating agent, wherein the process of dehydrating the pelts is soaked in the acetone for 3 times until the moisture content (calculated by mass fraction) in the dehydrating agent is 2.8%; after the bare skin is dehydrated, excess acetone is removed by adopting a through wringing machine for extrusion, the pressure of the through wringing machine is 0.4MPa, and the running speed is 3 m/min. Then the thin undenatured collagen flake material with the thickness of 0.5mm can be obtained after being evenly shaved by a shaving machine.
Example 3
Adjusting the thickness of the pig head skin after unhairing and liming to 0.8mm by using a skin splitting machine, and adjusting the pH value of the naked skin to 8.0 by using ammonium sulfate and formic acid according to a deliming method of conventional tanning processing; adding sodium hydroxide with the weight of 0.6% of that of the naked skin after the thickness of the naked skin is adjusted by a skin splitting machine for 3 times at intervals of 60min, and performing expansion treatment for 6h after the sodium hydroxide is added until the naked skin uniformly expands to be semitransparent; soaking the expanded pelts in methanol with the weight of 300% of the weight of the pelts for 90min, and then replacing a dehydrating agent, wherein the pelts are soaked in the methanol for 5 times in the dehydrating process till the moisture content (calculated by mass fraction) in the dehydrating agent is 2.4%; after the pelts are dehydrated, redundant methanol is removed by adopting a through wringing machine for squeezing, the pressure of the through wringing machine is 0.6MPa, and the running speed is 4 m/min. Then the thin undenatured collagen flake material with the thickness of 0.3mm can be obtained after being evenly shaved by a shaving machine.
Example 4
Adjusting the thickness of the two-layer pigskin after unhairing and liming to 0.9mm by using a skin splitting machine, and adjusting the pH value of the naked pigskin to 8.2 by using ammonium chloride and lactic acid according to a deliming method of conventional leather processing; adding urea with the weight of 2.0% of that of the naked skin into the skin splitting machine after the thickness of the naked skin is adjusted for 2 times at intervals of 90min, and performing expansion treatment for 6h after the urea is added until the naked skin uniformly expands to be semitransparent; soaking the expanded pelts in 300 wt% ethanol for 30min, and then replacing the dehydrating agent, wherein the pelts are soaked in ethanol for 6 times in the dehydrating process until the moisture content (calculated by mass fraction) in the dehydrating agent is 2.6%; after the pelts are dehydrated, redundant ethanol is removed by adopting a through wringing machine for extrusion, the pressure of the through wringing machine is 0.6MPa, and the running speed is 5 m/min. Then the thin undenatured collagen flake material with the thickness of 0.35mm can be obtained after being evenly shaved by a shaving machine.
Example 5
Adjusting the thickness of the cattle head layer skin after unhairing and liming to 1.2mm by using a skin splitting machine, and adjusting the pH value of the naked skin to 7.8 by using ammonium sulfate and an ammonia-free deliming agent according to a deliming method of conventional leather processing; adding potassium thiocyanate accounting for 1.5 percent of the weight of the bare skin after the thickness of the bare skin is adjusted by a skin splitting machine at one time, and performing expansion treatment for 3 hours after adding the potassium thiocyanate until the bare skin uniformly expands to be semitransparent; soaking the expanded pelts in 300 wt% ethanol for 60min, and replacing the dehydrating agent, wherein the pelts are soaked in ethanol for 4 times in the dehydrating process until the moisture content (calculated by mass fraction) in the dehydrating agent is 2.3%; after the pelts are dehydrated, redundant ethanol is removed by adopting a through wringing machine for extrusion, the pressure of the through wringing machine is 0.7MPa, and the running speed is 4 m/min. Then the thin undenatured collagen flake material with the thickness of 0.45mm can be obtained after being evenly shaved by a shaving machine.
Example 6
Adjusting the thickness of the dehaired and limitted sheep skin to 1.1mm by using a splitting machine, and adjusting the pH value of the naked sheep skin to 7.6 by using ammonium sulfate according to a deliming method of conventional leather processing; adding potassium hydroxide with the weight of 0.3% of that of the naked skin after the thickness of the naked skin is adjusted by a skin splitting machine for 2 times at intervals of 40min, and performing expansion treatment for 2h after the potassium hydroxide is added until the naked skin uniformly expands to be semitransparent; soaking the expanded pelts in acetone with the weight of 300% of the weight of the pelts for 45min, and then replacing the dehydrating agent, wherein the process of dehydrating the pelts is soaked in the acetone for 5 times until the moisture content (calculated by mass fraction) in the dehydrating agent is 2.9%; after the bare skin is dehydrated, excess acetone is removed by adopting a through wringing machine for extrusion, the pressure of the through wringing machine is 0.5MPa, and the running speed is 7 m/min. Then the thin undenatured collagen flake material with the thickness of 0.4mm can be obtained after being evenly shaved by a shaving machine.
Example 7
Adjusting the thickness of the dehaired and limitted goat skin to 1.0mm by a skin splitting machine, and adjusting the pH value of the naked skin to 8.0 by ammonium sulfate and formic acid according to a deliming method of conventional leather processing; adding sodium hydroxide with the weight of 0.4% of that of the pelts into the pelts after the thickness of the pelts is adjusted by a splitting machine for 2 times at intervals of 60min, and performing expansion treatment for 4h after the sodium hydroxide is added until the pelts are uniformly expanded to be semitransparent; soaking the expanded pelts in 300 wt% ethanol for 90min, and replacing the dehydrating agent, wherein the pelts are soaked in ethanol for 4 times in the dehydrating process until the moisture content (calculated by mass fraction) in the dehydrating agent is 2.5%; after the bare skin is dehydrated, excess acetone is removed by adopting a through wringing machine for extrusion, the pressure of the through wringing machine is 0.6MPa, and the running speed is 5 m/min. Then the thin undenatured collagen flake material with the thickness of 0.4mm can be obtained after being evenly shaved by a shaving machine.
Example 8
Adjusting the thickness of the dehaired and limitted sheep skin to 1.0mm by a skin splitting machine, and adjusting the pH value of the naked sheep skin to 8.3 by ammonium sulfate and lactic acid according to a deliming method of conventional leather processing; adding urea with the weight of 1.5% of that of the naked skin into the skin splitting machine after the thickness of the naked skin is adjusted for 3 times at intervals of 30min, and performing expansion treatment for 3h after the urea is added until the naked skin uniformly expands to be semitransparent; soaking the expanded pelts in 300 wt% of ethylene glycol ether for 90min, and then replacing the dehydrating agent, wherein the pelts are soaked in the ethylene glycol ether for 3 times in the dehydration treatment process until the moisture content (calculated by mass fraction) in the dehydrating agent is 2.8%; after the pelts are dehydrated, redundant ethylene glycol ethyl ether is removed by adopting a through wringing machine for squeezing, the pressure of the through wringing machine is 0.6MPa, and the running speed is 6 m/min. Then the thin undenatured collagen flake material with the thickness of 0.3mm can be obtained after being evenly shaved by a shaving machine.
Claims (7)
1. A preparation method of thin type undenatured skin collagen sheet material is characterized in that after the thickness of a peltry after unhairing and liming is adjusted to 0.8-1.4mm by a skinning machine, the pH value of the peltry is adjusted to 7.5-8.5 by a deliming agent according to a deliming method of conventional leather processing; expanding the delimed pelts by using an expanding agent until the pelts are uniformly expanded to be semitransparent; soaking the expanded pelts in a dehydrating agent with the weight of 300 percent of the weight of the pelts for at least 30min, and then replacing the dehydrating agent, wherein the pelts are soaked in the dehydrating agent for 3-6 times in the dehydrating process, and the dehydrating agent is any one of methanol, ethanol, acetone or ethylene glycol ethyl ether; after the pelts are dehydrated, a through wringing machine is adopted to squeeze and remove the redundant dehydrating agent, and then a shaving machine is used for shaving to obtain the thin type collagen sheet material with the thickness of 0.3-0.5 mm.
2. The method for preparing a thin undenatured skin collagen sheet material according to claim 1, wherein the pelts after depilation and liming are any one of goat skins, sheep skins, cow skins or pig skins.
3. The method for preparing a thin undenatured collagen skin sheet according to claim 1, wherein the deliming agent is one or two of ammonium sulfate, ammonium chloride, formic acid, lactic acid and ammonia-free deliming agent.
4. The method for preparing a thin type undenatured collagen flake material according to claim 1, wherein the swelling agent is any one of sodium hydroxide, potassium hydroxide, urea or potassium thiocyanate, and the amount of the swelling agent is 0.2-2.0% of the weight of the pelts after the thickness of the pelts is adjusted by the flaking machine.
5. The method for preparing a thin undenatured collagen skin sheet according to claim 1 or 4, wherein the swelling agent is added in 1 to 3 times, each time at an interval of 30 to 120min, and the swelling treatment time is 2 to 6 hours.
6. The process for producing a thin undenatured collagen skin sheet according to claim 1, wherein the total time of dehydration is 4 to 12 hours and the end point of the treatment is that the moisture content in the dehydrating agent is less than 3.0% by mass.
7. The method for preparing a thin undenatured collagen skin sheet according to claim 1, wherein the passing wringing machine has a pressure of 0.4-0.7MPa and a running speed of 3-8 m/min.
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