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 providing testing on parallel groups of fur sheepskin after pickling on three topographic portions of sheep skin surface: skirt, spine and neck portions; processing samples of each group with acid-salt solution for 24 hours; withdrawing sheepskins of each group from acid-salt solution in predetermined time intervals; removing excessive liquid; placing said samples into tensile testing machine and stretching lengthwise of spine line by 40% relative to initial length thereof; holding samples in stretched state for 1 min and withdrawing from tensile-testing machine; leaving samples in free state for 10 min; determining residual elongation value in mm.

EFFECT: 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 for the dressing of fur and sheepskin raw material for assessing the quality of tropicaliente the leather.

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

There is a method of determining tropicaliente, consisting in the sample on Sosenko or use temperature welding. Determination of temperature welding is that a strip of leather semi-finished product is heated in water or in equilibrium pikelner solution, or a mixture of glycerin with water and note the temperature at the time when the shortening of the sample (see Volkov V.A., Purimu N.T. Technology analysis and control of leather manufacture, M.: Light industry, 1972, p.131-133).

Using for this purpose the temperature of the welding does not give a clear picture, because it depends on the type and age of the animal, and the way is long.

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

The technical result of the invention is to reduce the time to determine the quantitative characteristics of tropicaliente Koshevoy daniute determine the degree of its opening.

The technical result is achieved by a method for determining tropicaliente leather, characterized by the fact that determine its plastic properties, and the leather after pickling stretch for 40% of the original length, is kept in the stretched state for one minute, relieve tension and incubated for ten minutes in a free state, and then determine the amount of permanent elongation.

A distinctive feature of the proposed method is that when determining the quantitative characteristics of tropicaliente the leather used for the residual elongation after stretching the leather to 40% of the original length) and incubation for 10 minutes in a free state.

Stretching the leather of 40% was determined experimentally, as this value is the maximum without breaking the leather. The decrease in the elongation of less than 40% is undesirable, since it reduces the accuracy of the experiments and the effect of pickling is manifested with less distinctness.

Extract the leather after stretching for 10 minutes required to bring it into equilibrium, because this time there is complete relaxation of internal stresses, therefore, to increase the duration of aging is not meaningful.

Found by the authors Velich is the residual elongation 26± 2% is in good agreement with the results of the organoleptic evaluation tropicaliving leather and little depends on the topographic site skins.

Conducted by the applicant's analysis of the prior art, including searching by the patent and scientific and technical information sources, and identify sources that contain information about the equivalents of the claimed invention, has allowed to establish that the authors have not identified the sources with characteristics identical with all the essential features of the claimed method to determine tropicaliente the leather. To determine from the list of identified unique only analogue, which could be taken for the prototype is closer to the totality of symptoms similar, the authors failed to install. The set of essential features set forth in the claims against perceived by the applicant to the technical result - the reduction of time to determine the quantitative characteristics of tropicaliente the leather.

Therefore, the present invention meets the conditions of "novelty" and "inventive step".

How to determine tropicaliente the leather is as follows.

Sheepskin, after pickling press, determine and mark the work area without cutting samples using a bursting machine with special and clamps stretch it to 40% of the original length after holding this position for one minute will relieve tension and incubated for ten minutes in a free state, again determine the dimensions of the original plot. The obtained values of the residual elongation will characterize tropicaliente the leather.

Studies conducted in parallel groups fur sheepskin, after pickling. To assess tropicaliente use three different topographic area of the skin of the sheep: gender, spinal and neck.

As an example pikelny systems take the acid-salt solution consisting of a mixture of acetic and sulfuric acid concentration of 3 and 1.5 g/cm3accordingly, and salt 40 g/cm3. Pickling is carried out at liquid ratio LC=7, temperature 38°within 24 hours

After a certain period of time sheepskin alternately extracted from the acid-salt solution and freed from excess liquid by squeezing, then placed in a tensile machine and stretch 40% of the original length in the longitudinal direction relative to the spine line. This value is found experimentally, which corresponds to the maximum tensile samples, without a break, all three topographical areas.

In the stretched state areas sheepskin stand one minute, then remove them from p is sryvnoy machine and leave in a free state within ten minutes, then determine the amount of permanent elongation.

When pickling macromolecule collagen undergo structural changes, resulting in the separation of the bundles and fibers into smaller elements. The reduction in intensity megapackage interaction under the action of acid affects the ability of the structural elements of the collagen to the phenomena orientation in the process of deformation of the samples of the dermis and possibly causes the dependence of the residual elongation from the intensity of pickling. This figure was supposed to be used as criteria for evaluating tropicaliente in a production environment.

Example 1. The study was conducted in parallel groups fur sheepskin, after pickling and in three topographical areas of skin sheep: gender, spinal and neck.

As pikelny system was taken acid-salt solution consisting of a mixture of acetic and sulfuric acid concentration of 3 and 1.5 g/cm3accordingly, and salt 40 g/cm3Flat=7, temperature 38°With the duration of 24 hours

After a certain period of time sheepskin each group in turn is extracted from the acid-salt solution and freed from excess liquid, and then placed in a tensile machine and stretch up to 40% of the original is th length in the longitudinal direction relative to the spine line. This value is found experimentally, which corresponds to the maximum tensile strength of the samples without breaking each of the three plots. In the stretched state, the samples incubated for one minute. Then remove them from bursting machine and leave in a free state within 10 minutes, and then determine the amount of permanent elongation.

Testing is carried out as follows. On the skins of sheepskin, past pickling and pressed to a moisture content of 50%, determine and mark the area with a length of 50 mm along the spine line of skins and a width of 10 mm work area whole sheepskin fix the exact middle of special clamps bursting machine to the geometric axis of the plot is located vertically. The speed of movement of the clamp must be 100±20 mm/min At the age of elongation corresponding to 40% of the original length of the work area, breaking the car off, the plot sheepskin withstand voltage 1 min, then give the car to reverse, relieving tension. Work area is kept for 10 min in a free state, as of the moment of stress. After 10 min "rest" off-net extension of the work area in mm

Relative residual elongation (E) in percent is calculated by the formula:

where E is the relative residual of odlin the tion, %;

Δl1- increase the length of working area, mm;

l0- the initial length of the work area, mm

Pickling passed satisfactorily, if the indicator residual elongation of not less than 26±2%.

The results obtained are summarized in table 1, which reflects the residual elongation of the different parts of the leather sheepskin depending on the time of pickling.

Table 1
The time of pickling, hResidual elongation, %
FloorThe spinal partNeck
0,022±1,2514±2,8220±1,67
1,516±2,1414±1,7316±2,05
3,020±1,6616±2,1320±1,25
4,521±2,4520±1,1620±1,50
6,524±1,0522±2,2524±1,90
24,028±1,5028±2,2528±1,5
72,026±2,1124±1,4426±2,25

As can be seen from table 1, most of ostatok the second extension to the pickling floors skins (22%). The spinal part has the smallest residual elongation of 14%. This is because collagen bundles plots the floor and the neck part and thin, loosely interwoven, are rather loosely, and the spinal part of the skins is extremely difficult interwoven network loop which is thick and densely adjoin to each other in a different direction. (Sokolov V.E., Petrishchev NR. The skin of domestic mammals (ungulates). - M., 1997, 288 S.)

From the data presented in table 1, it is seen that with increase in the duration of pickling is an increase in residual elongation for all topographical areas. This quantity tends to the total for all sectors value, in this case 26±2%, i.e. plastic deformation during the pickling increase.

The ability of collagen fibers to the orientation depends on the intensity megapackage interaction in its structure, including the interaction between the chains with the formation of strong cross-links between them. (Kotanen Role of GI mifepristone flow circuits in the formation of the strength properties of the skin/ Leather and footwear industry, No. 5-6, 1995, pp.31-32). During pickling, due to the action of acids, decreases megapackage interactions in the collagen structure, individual elements of the dermis become more flexible, increase the tsya their ability to form areas oriented in the direction of the action of external forces molecular chains. With fewer cross-links between chains under the action of acid, increases the number of loose sections of the grid. As a consequence, increases formiruemoi areas, and together with it and the entire area of the dermis regardless of topographical parts of the skin.

Example 2. Pickling fur sheepskin is carried out in an aqueous solution containing 40 g/cm3sodium chloride, 2.4 g/cm3sulfuric acid, 2 g/cm3acetic acid, LC=5 and a temperature of 40°C. the duration of the process 14 PM

After pickling sheepskin squeezed and determine the residual elongation after stretching by 40% in the longitudinal direction, is kept in this state for 10 minutes, then determine the amount of residual elongation, which amounted to 26%.

After pickling fur sheepskin is treated on "Technologies of processing of fur skins" (Createrepo, 1982) to finish unpainted bulk.

Qualitative indicators fur sheepskin are shown in table 2.

td align="left"> Mass fraction of chromium oxide, %
Table 2
IndexAccording to GOST 1821-75According to the invention
Temperature welding, °At least 8085,0
Mass fraction of moisture, %No more than 149,5
1,5-3,52,4
Mass fraction of ash, %No more than 9,06,5
Mass fraction of unbound fatty substances, %No more than 127,3
the pH of aqueous extract4.06,7
The load at break of the whole lambskin, N.Not below 250350
Elongation at tension of 9.8 MPa, %No more than 30,025,0

For sensory assessment of the leather sheepskin was soft and answered the requirements.

The results for the residual elongation (see table 1) are in good agreement with the assessment of tropicaliente traditional organoleptic methods.

The claimed method of determining tropicaliente is non-destructive, it is suitable for production purposes, as it does not require time-consuming to conduct valuations of tropicaliente on a tensile testing machine. This method can be recommended for use on the skins of various breeds of sheep, but also to determine tropicaliente any fur raw materials. In this case it is necessary to experimentally determine the maximum amount of stretch.

On the basis of vychislitel is possible to make a conclusion on the conformity of the proposed method the criterion of "industrial applicability".

How to determine tropicaliente leather fur, characterized by the fact that determine its plastic properties, and the leather after pickling stretch for 40% of the original length, is kept in the stretched state for one minute, relieve tension and incubated for ten minutes in a free state, and then determine the amount of permanent elongation.



 

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

SUBSTANCE: method involves providing testing on parallel groups of fur sheepskin after pickling on three topographic portions of sheep skin surface: skirt, spine and neck portions; processing samples of each group with acid-salt solution for 24 hours; withdrawing sheepskins of each group from acid-salt solution in predetermined time intervals; removing excessive liquid; placing said samples into tensile testing machine and stretching lengthwise of spine line by 40% relative to initial length thereof; holding samples in stretched state for 1 min and withdrawing from tensile-testing machine; leaving samples in free state for 10 min; determining residual elongation value in mm.

EFFECT: reduced time for determining quantitative pickling characteristic of skin web.

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