Method for determining pickling extent of leather web

FIELD: fur industry, in particular, method for evaluating pickling quality of leather web in tanning of fur and sheepskin raw material.

SUBSTANCE: method involves determining quantitative pickling characteristic of leather web of semi-finished product by using time of solving thereof in alkaline solutions, said time depending on number and kind of intermolecular bindings destructed during pickling. Solving of collagen in alkaline solutions depends upon nature of preliminary acidic preparing procedure. Solving is provided in aqueous solution of potassium hydroxide having concentration of 150 g/l and temperature of 18-20 C. Derma solving time is found after preliminary thermal processing at temperature of 60-65 C during 1.5 hours. Method may be employed both in production of fur and sheepskin products and in fur processing.

EFFECT: wider operational capabilities and reduced time for determining quantitative pickling characteristic of skin web.

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The invention relates to the fur industry and can be used in the preparatory processes for the dressing: pickling, abating, the pickling of fur and sheepskin raw material.

Currently there is no clear quantitative characteristics of tropicaliente the leather.

There is a method of determining tropicaliente leather, providing indirect determination of its breakdown to "Sosenko", and the pH value of the slice (see Ipomeanol, Aourir. The basic technology of fur, M Gisleham, 1956, str-127).

However, using for this purpose the pH of the slice does not provide information about the loosening of the dermis, and indicates the depth of penetration of the acid and its distribution over the layers.

The technical object of the present invention is to provide a method for assessing tropicaliente for industrial purposes that do not require much time to experiment.

The technical result of the invention is to reduce the time of assessment for quantitative characteristics tropicaliente the leather by determining its degree of fragmentation.

The technical result is achieved by a method for determining tropicaliente leather, characterized by the fact that determine the degree of its opening time of the dissolution of the dermis in alkaline solution, and after pikel is of the weighed samples skins weighing 10 g shear off hair, crushed into pieces the size 5×5 mm, then the samples are subjected to additional heat treatment at a temperature of 60-65°in distilled water for 1.5 hours, followed by washing to remove free acids, and the dissolution is carried out in a solution of potassium hydroxide at concentrations of 150 g/l, a temperature of 18-20°C.

A distinctive feature of the proposed method is that when determining the quantitative characteristics of tropicaliente the leather use the time of its dissolution in alkali, which depends on the amount and kind of ruined intermolecular bonds during pickling.

Moreover, the dissolution of collagen in alkaline solutions is influenced by the nature of the preliminary acid preparation. The dissolution is carried out in an aqueous solution of potassium hydroxide at a concentration of 150 g/l, a temperature of 18-20°C. And the time of the dissolution of the dermis is found after preliminary heat treatment at temperatures above 60-65°C for 1.5 hours.

To eliminate the influence of the size of the sample and accelerate the dissolution of the leather it was found experimentally that the leather, chopped into pieces the size 5×5 mm, dissolves quickly and allows you to accurately set the time for complete dissolution.

Preliminary experiments it was found that heat treatment of the Skye treatment at a temperature of 60-65° C for 1.5 hours significantly reduces the duration of the analysis on tropicaliente the leather up to one hour or less. This allows you to more quickly obtain information about the state of the semi-finished product.

When studying the influence of the nature of alkali on the intensity of dissolution of collagen was found that the CON is most suitable because it allows you to more clearly define the degree of loosening of the dermis, in addition, the process of dissolution of the leather at a concentration of 150 g/l occurs rapidly.

To obtain stable results and elimination of losses of alkali to neutralize the free acid in the leather, the samples prior to analysis should be rinsed with distilled water.

Thus, a new set of methods, parameters set forth in the claims method for determining tropicaliente leather fur semi-finished product, ensures the achievement of the technical result consists in reducing the time of assessment for quantitative characteristics tropicaliente the leather.

Comparison of proposed method with other known technical solutions of the prior art in the patent and scientific documentation has allowed to establish that the authors have not identified a solution that includes a set of features, similar or equivalent is claimed, that allows to make a conclusion about conformity of the present invention, the criteria of "novelty" and "inventive step".

How to determine tropicaliente the leather is as follows: sheepskin or fur semi-finished product after the process of pickling selected samples with bobbed hair, crushed into pieces the size 5×5 mm, and then subjected to additional heat treatment at a temperature of 60-65°in distilled water for 1.5 hours, followed by washing to remove free acid and the dissolution of the leather carried out in a solution of potassium hydroxide at a temperature of 18-20°C, the concentration of potassium hydroxide and 150 g/l until the complete disappearance of the phase boundary (to obtain a homogeneous solution).

Example 1. For studies using samples taken from the skins of fur sheepskin, after degreasing. Pickling is carried out at LC=7, temperature 38°C for 8 hours. To study the effect of composition pikelny baths on the leather fur sheepskin pickling is carried out in solutions of formic, acetic and sulfuric acids 5 different concentrations: 2; 4; 10; 20; 40 g/l Concentration of sodium chloride in all pikelny composition was 50 g/l

One way of dissolving collagen in alkaline medium is joining him in acid solutions (the Language is s VK, Lobsanova LB Removal of carbohydrate compounds during welding of collagen // Modern technologies of production of non-woven materials, film materials, leather and fur: interuniversity collection of scientific papers, sproutd. - SPb., 2000. - s-154), which is the destruction of various types of intermolecular cross-linking and the change in the conformation of polypeptide chains.

So after pickling sample sample skins weighing 10 g (hair shorn) is crushed to sizes 5×5 mm And is subjected to additional heat treatment in distilled water at a temperature of 60-65°C for 1.5 hours. This was followed by washing to remove free acids after acid treatment prior to the disappearance of the transition of the indicator methyl orange red. Directly dissolving collagen carried out in parallel with solutions of sodium hydroxide and potassium hydroxide with a concentration of solutions of 150 g/l at a temperature of 18-20°C. Experience carried out at constant mechanical action in the shaker type WU-3. When placing cooked and washed specimens in alkaline solution was an intensive absorption of hydroxyl ions, which was accompanied by swelling of the leather, destruction deletelabel links. The time of dissolution was recorded at a time when the whole sample into homogeneous colloidal shall actor. The results are shown in the table.

Table

The dependence of the duration of the dissolution of the collagen composition pikelny baths.
The concentration of acid, g/lContinued dissolution, h
In caustic soda solutionIn the solution of caustic potassium
antaceticsulfurantaceticsulfur
2over 24over 24over 24over 24over 24over 24
4more than 1212,0018,00of 5.406,503,90
108,0010,0011,002,202,703,00
204,335,00and 5.300,851,002,00
403,003,204,500,660,801,70

From the table it is seen that the concentration and type of acid in the pickle affected naccarati dissolution of collagen in dilute alkali. Kind of alkali also affects the dissolution of collagen. A solution of potassium hydroxide promotes more intense swelling and dissolution of collagen, thus, when the concentration of acids 4 g/l dissolve in caustic potassium occurred for 6.5 hours, while in caustic soda solution with the same concentration of acid it took more than 12 hours. When the concentration of the acid 40 g/l when pickling samples dissolved in potassium hydroxide three times faster than sodium hydroxide. This was to be expected, since the CON more intensively affects collagen than NaOH (A. Mikhailov. The collagen of the skin and the basis for its processing. - M: Light and food industry, 1978. - 525 C.).

As the table shows, with increasing concentration of acid duration of dissolution is reduced. So, when the concentration of the acid 2 g/l dissolve lasted more than 24 hours (KOH solution), whereas at a concentration of 40 g/l, the same effect was obtained for formic acid for 0,66 h, acetic acid at 0.8 h, sulfuric for 1.7 hours

Comparing the effect of the nature of the acid, which was conducted pickling, shows that formic acid has a greater impact on the collagen structure.

Dissolution of collagen after treatment in a solution of formic acid is faster than after treatment with other acids. After treatment in sulphuric pickle solution is of the collagen in the alkali longer than after treatment in pikelny systems containing organic acids. This can be explained by the orientation of the action of organic acids to a greater extent on intermolecular connections.

The difference between the action on collagen organic acids explains the fact that formic acid in anhydrous condition not only causes swelling of collagen, but in contrast to acetic acid dissolves it (A. Mikhailov. The collagen of the skin and the basis for its processing. - M: Light and food industry, 1978. - 525 C.). Although it is known that the temperature of the welding biggest influence sulfuric acid and to a lesser extent organic acids. Data on the duration of the dissolution of collagen in alkali after acid treatment are in good agreement with organoleptic evaluation of air-dry material; the softer the leather had samples with less duration of dissolution in alkali.

The advantages of the proposed method of determining tropicaliente leather are:

- the possibility of application of the method in the production of fur and fur sheepskin, and in the processing of fur when performing pickling, bating, pickling sheepskin and fur raw materials to assess tropicaliente,

- the use of the assessment method for manufacturing purposes does not require large for the Rath time for experience.

The above will allow to make a conclusion on the compliance of the claimed invention, the criterion of "industrial applicability".

How to determine tropicaliente leather, characterized by the fact that determine the degree of its opening time of the dissolution of the dermis in alkaline solution, and after pickling the weighed samples skins weighing 10 g shear off hair, crushed into pieces the size 5×5 mm, then the samples are subjected to additional heat treatment at a temperature of 60-65°in distilled water for 1.5 h, followed by washing to remove free acids, and the dissolution is carried out in a solution of potassium hydroxide at a concentration of 150 g/l, a temperature of 18-20°C.



 

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