RU1777608C - Method for machining leather for shoe vamp - Google Patents

Abstract

The essence of the invention: the skin after retanning is neutralized for 1 h to pH 6, treated with acrylic ether in an amount of 7 g / l at 50 ° C for 0.5-2 hours and the acrylic ester is polymerized with formic acid, after drying the skin they are treated under pressure of 20 kg / cm2 at 100-120 ° C for 4-8 seconds, punch holes and treated with a solution of methacrylic resin in an amount of 4-6 g / l at 50-60 ° C and for 30-45 min. Resin is polymerized by adding (formic acid, 1 table. 2 silt

Description

The invention relates to a method for producing leather for manufacturing a shoe front. In particular, the invention relates to a method for processing sheep's skins to produce punctured or punched holes, which is compact and tough to use in the manufacture of a front shoe with wool on its inner surface for wear in the spring and summer.

This method differs from the traditional operations carried out on sheepskin with wool, and the treatment of hides with acrylic and methacrylic resins, respectively, after the steps of retanning and piercing holes.

Known shoes that are suitable for wearing in hot months, especially for summertime and in which

a front with punctured or punched holes is used, made of distinguished calfskin and not lined on the inner surface, the front being characterized by the compactness and durability necessary for such a special application. However, products made of such leather have the disadvantage that they are not hygienic due to the presence of holes, as well as the inconvenience of creating friction, which is inevitable between the inner surface of the front and the sole, and also unsatisfactory heat transfer between the remote control and the visible and internal surfaces which is necessary to reliably maintain optimal temperature inside the shoe. In other words, the solutions proposed to obtain the leather used in the manufacture of shoes for the summer season are based, in general,

WITH

XI XJ XI

Och

00

about

the use of materials such as, for example, fabrics that are capable of sweating, however, there is no doubt that such materials cannot be used to make durable shoes that are not subject to rapid wear due to weather conditions, impacts or other external factors. Thus, the need for leather intended for the manufacture of shoe front for the hot season is quite obvious, and the front side, although provided with holes or holes, does not have the aforementioned drawbacks and, in addition, allows the manufacture of shoes having the required properties. namely, durability, durability, and comfort. In order to satisfy such a requirement, it is proposed to use leather as a starting material for making the front of summer shoes according to the present invention with punched holes obtained from sheep's skins, which, due to the presence of a layer of wool on its inner surface, can form a coating capable, due to its nature, of maintaining a constant internal temperature, as well as ensuring air circulation, thus preventing leg overheating and therefore perspiration, and due to its antistatic effect dust is reduced. In addition, the skin obtained according to the invention has such a distinctive property as the absence of localized compression in any part of the sole, so that the same comfort is ensured and, finally, such skin is suitable as a stimulator of peripheral blood circulation and as a material capable of absorbing electrostatic energy that accumulates in the human body o However, in order to be able to use sheep skin with wool as a starting material, it is impossible not to take such initial properties into account such as, for example, a sufficiently open fibrous texture due to the large amount of hair and also the presence of very short fibers, which make such material unsuitable for use in the manufacture of front shoes. So that in the skin with holes

0

5

0

5

0

5

0

5

0

5

made from sheep's skins with wool, which could be used to make shoes for the spring-summer season, it is proposed according to the present invention to carry out the processing of acrylic and methacrylic resin at the end of the retanning step and after the punching stage.

Indeed, thanks to such operations, a dual goal is achieved:

a) the skin is given compactness and strength so that it can be pierced without risk of tearing and the front can be made by pulling the skin onto the desired model;

c) the strength of the skin at the points corresponding to the inner surfaces of the holes is increased, so that it is not stretched and torn at the points corresponding to the said holes when worn out.

As mentioned, the main operations of the method according to the invention are the deposition and subsequent two-stage polymerization of acrylic resin inside the fibrous structure of the skin and the deposition and subsequent polymerization of methacrylic resin at the points corresponding to the inner surfaces of the holes or holes at the time of dressing the skin with a retanning and finishing processing according to the traditional method, The traditional skinning process technology usually includes various stages of processing in the bath, as well as various passed stages of dry processing. More precisely, the traditional process carried out in a bath proceeds according to the following processing steps: a) a wet step, in which the skins are released from organic residual matter and blood and softened to eliminate the need for subsequent processing of facial fibers in a bath which consists of cold water and a surfactant, for example, FORYLL BB (a mixture of both anionic and nonionic type feed agents supplied by Henkel Company); then the skins are adjusted to their natural concentration of water during the action of the enzyme product (an enzyme-based product obtained from pancreatic bacteria, for example, REVERDASE

120 (Rohne Poulenc); c) a stage of haemorrhage, in which pieces of meat and fat remaining after the skinning operation are removed, while the subcutaneous layer is also removed so that tannins can easily penetrate the skin, more evenly and quickly; c) a washing step in which the remaining dirt and part of the natural fats that are present are removed from the skins, the natural fats remaining after this step becoming more evenly distributed, this step is carried out using i preferably emulsified perchlorethylene, which accelerates processing, d) a pickel stage, which represents the stage of transition from biological to ana biological state, during which the skins are prepared for chrome tanning; f) a tanning step in which the usual treatment with chromium salt (basic chromium sulfate, 8) is carried out to obtain a skin that is compact enough and low elastic, allowing sweat to be released; f) an acid removal step in which, after tanning within about 48 hours of being on the deck, the hydrolyzable acid bound to the protein substance is neutralized (since such acid causes an uneven dyeing) with a compound consisting of a mixture of buffer salts which render neutralizing effect (for example, Coratil ND, a product from Henkel); g) a retanning step in which the hide obtains greater strength and volume, as well as better blanching ability, etc. Dry processing of a conventional type is based, on the contrary, in the sizing, puncturing or punching steps and subsequent finishing. According to the present invention, such processing steps form a whole of the two mentioned steps, in which the processing is carried out with acrylic resins. In particular, during the retanning step, more precisely at the end of the retanning operation, an acrylic resin, namely acrylic ester, is applied to achieve hardening of the fibrous structure, which, when it is introduced into the fibers and polymerizes, forces the fibrous

the structure is thickened so that, in addition to high compactness and strength, the skin also obtains the strength necessary for the subsequent hole punching operation. Another operation that characterizes the proposed method is carried out during dry processing after the piercing or punching holes, and it involves treating the exposed surface of the skin, inside the holes, with methacrylic resin to increase the strength of the surface at points corresponding to the inner walls of the holes so that so as to eliminate the risk of stretching and tearing of the skin during application. Therefore, the main objective of the invention is a method for producing leather intended for the manufacture of a shoe for the spring-summer season, in which the skin of a woolly sheep is treated in a bath and then subjected to dry treatment, wherein the treatment in the bath consists of steps of draining water, mesentery washing, pickling, tanning, acid removal and retanning, and dry

0 processing includes a first sizing step; a piercing or punching step, and a second finishing step, characterized in that, at the end of the duplication step 5, the hide is treated with an NOT acrylic ester resin in an aqueous solution and then the resin is polymerized so that the initial fibrous structure becomes thicker and that after a step punching holes of the skins is treated with methacrylic acid in an aqueous solution, the resin polymerizes at a point corresponding to the inner surface of the holes. The selection of the type of acryl polymer proposed in the present invention for the final phase of the retanning operation is interesting and rational when compared with a melamine type resin or

0 Urethane, dicyandiamide, polyurethane and oleomaleic types that are commonly used for this operation. Really good from, it is known that some of the

The 5 resins, and in particular the polyurethane and oleomaleic resins that are commonly used, do not provide a sufficient degree of compactness and skin firmness. For the same reasons, melamine and urethane resins should also be excluded, although such resins have the advantage of providing sufficiently good properties, namely a good feeling when the skin is touched and soft. D. Dicyandiamido-type resins, which, on the contrary, can provide the required strength properties, are unsuitable for the purpose of the present invention, since they degrade to a considerable degree the properties obtained at the stage of chromium tanning and especially the dyeing ability of the skin. The solution of the present invention to use acrylic resins in the form of aqueous solutions rather than in the form of aqueous dispersions aims to achieve a better and more complete penetration into the skin instead of surface deposition, which may cause the product to become excessively hard, and in addition this solution allows the use of anionic dyes for skin with increased reliability. In the method of the invention, the polymer compound of acrylic ester is added to a neutralization bath consisting of water at 50 ° C and an agent for removing acid (for example, the aforementioned Coratil ND) into which the skins are dipped and in which the pH is adjusted to about 6. It is interesting to note that the use of a neutralizing bath according to the present invention also allows the polymer to penetrate effectively an acrylic ester compound, for example, ICATAN 38 from leap.

The acrylic ester resin is added to the neutralizing bath, preferably about 1 hour after completion of the neutralization at a concentration of 7 g / l, to enable it to penetrate to a large extent into the skin fibers at points where the skin itself is less durable and more precisely in the lateral parts. where the structure is less subject to relaxation and the fibers are long. Also, according to the present invention, an acrylic ester resin is made, after a period of from 30 minutes to 2 hours, when the resin completely penetrates the skin, polymerize first with a slight addition of formic acid so that the resin binds to the skin fibers and then

e e, e y10

fifteen

twenty

25

7776088

forced to polymerize a second time in a dry state directly on the skin, which is now completely dry, at a pressure of 20 kg / cm2 and at a temperature of about 100-120 ° C for k-8 s

After the step of piercing the sheepskin, which is carried out on a press having small punches in the punches, the treatment with methacrylic resin is carried out according to the described method. Preferably, this treatment is carried out in a water bath at 50-60 ° C., to which a prepolymerized methacrylic acid resin (e.g. Henkel Drasil-ANG) was added at a concentration of about 4-6 g / l, the resin was forced to polymerize using an additive formic acid for 30-45 min. at - Thus, the resin is deposited on the surface of the punctured hide at points corresponding to the inner walls of the holes, where the resin itself is absorbed by uncoated fibers as a result of the effect of the piercing stage, as a result The predominant effect is, as already mentioned, an increase in the strength of the skin surface.

The purpose of the invention is to improve the quality of the skin.

FiK1 shows a process flow chart according to the present invention; in FIG. 2 is a schematic perspective view of a shoe made from leather obtained in accordance with the proposed method.

As shown in FIG. 1, various working steps for processing a sheep’s skin can be noted, for example, steps divided into group D, which includes steps that are typical for processing in a bath, and group B, which includes steps that are typical for dry processing . The distinctive stages in the proposed method are two treatments with acrylic and methacrylic resins, respectively, which are carried out during the final part of the retanning process included in group A and after the stage of punching holes in group B. In group A, the biological processing phase, including the winding stage, can be noted , the stage of mesentery and washing, the transitional stage, consisting of the operation of pickling and anabiological stage, including30

35

40

fifty

5

9

during tanning, cyst removal and retanning operations. Dry processing (B) includes sizing, punching, treatment with a methacrylic polymerizing compound, which is a hallmark of the proposed method and the subsequent finishing step. More precisely, the technology shown, which is characteristic of the method according to the invention, can be briefly described as follows: a) raw material from the skins of woolly sheep is dipped in a bath of cold water (one skin for each volume of water of 20 liters), and the bath contains FORYLL BB surface the active substance supplied by Henkel at a concentration of 1 g / l, the bath is made overnight, and in the morning it is washed with tap water until the water is clear, then REVEKDASE 120 (0, 2 g / l) and FORYLL BB (g 1 / l) and skins are left in the bath for 48 hours (stage soaking);

b) after the stage of mesentery, a bath is prepared consisting of water at and 1.5 g / l of perchlorethylene

(as a solvent) and 3 g / l FORYLL BB (surfactant), and the skins are left immersed in such a bath in a proportion of one skin for every 20 liters, then the skins are washed with running water;

c) a cold water bath is prepared with 40 g / l of salt added (approximately 4 Be) and the skins are left in such a bath in the proportion of one skin for every 20 l of bath for 30 minutes, then 2.5 g / l of organic acids (for example, BASCAF F from BASF) and the bath are left for 2 hours, then 3 g / L formic acid is added and the skins are kept in the bath for 2-3 hours at a pH of 2.8 (stage of pickling). The purpose of this pickling operation is to prepare the skins for the chromium tanning step to make them more suitable for passing quickly through the chromium salts, which, due to the acidic nature of the bath, become less reactive so that their penetration becomes more uniform. Salt addition is necessary to prevent swelling of the skins due to the effect of the presence of acid;

10

10

5

0

d) the hides are then treated as follows (tanning step): soak for 2 hours in a cold water bath (one skin for every 20 liters) containing liquid chromium salt, then 1.6 g Henkel Crassan DHS is added to the bath / l, the bath is left for 1 h, then IMPLENAL AP supplied by BASF is added, and the hides are kept in the bath for an additional T h and finally 10 g / l of liquid chrome salt is added while maintaining the hides in to said bath for 2-3 hours, finally add 1 g / l sodium carbonate and 1 g / l sodium bicarbonate and, if the skins are immersed in this bath for hr, then the skin is stretched on a last. The method carried out in this way allows one to obtain leather suitable for making the shoe front, since skins that are well tanned, have a temperature Tg of about 90 ° C, are soft, touch-like rubber, compact enough and poorly elastic and, moreover, can tolerate free sweating. Indeed, as you can see, in addition to basic chromium sulfate, introduced at a pH of about 2.8, which facilitates uniform penetration, synthetic sulfite fat, which is electrolyte resistant (Crassan DHS), as well as a protective agent ( IMPLENAL AP), which exhibits the filling and stabilizing effect of chrome tanning. The final addition of the alkaline compound at the final stage serves to enlarge the chromium compound molecule and fix it on the skin between its fibers to obtain a tanned skin with good, firmness and. persistence; f) at the stage of acid removal, which is carried out after aging the selected hides by holding them for about 48 hours on the deck, a water bath is used at about 45 ° C, into which the hides are dipped (in the amount of one skin for every 20 liters of water); then 2 g / L Coratil ND was added, treatment was carried out for one hour, then 3 g / L Crassan DHS was added and treatment was carried out for another hour; f) the stage of retanning is completed after its completion in

0

5

0

45

0

5

eleven

in accordance with a known method by treatment with acrylic resin, which treatment is a hallmark of the present invention; based on experience, the skins are treated in a bath with water at a temperature (in the amount of one skin for every 8 liters of water) containing g / l Coratil ND and 7 G / L ICATAN 38. After the skinning of the skin was blanched and after dyeing the skin, dry processing; d) after the usual sizing operation by applying to the skins an aqueous suspension of aliphatic polyurethane (Astaein Finich PUD) in an amount of 8p-100 g / skin at a temperature of 110 ° C and a pressure of 150 atm. followed by the formation of a polymer coating, a hole punching operation is carried out. The second step, which is a distinguishing feature of the invention, is carried out by dipping the skin in a bath of water at 50-60 ° C, above; Drasil-ANG, obtained from Henkel, which is a prepolymerized methacrylic resin in an aqueous solution at a concentration of 4-6 g / l. Then, formic acid was added over a period of 45 minutes at a temperature of 60 ° C and the polymerization was completed to form a coating on the surface of the broken skin at the points corresponding to the inside of the holes (h) and after that additional finishing (i) was carried out. FIG. Figure 2 shows the use of the leather obtained in accordance with the present invention for the manufacture of a shoe front; moreover, on the inside of the shoe, a layer of wool 1 can be seen, while on the outside of the shoe the skin is velor or pile leather 2 provided with holes 3. The results of the following some standard tests are reported to determine the properties required for the leather intended for making a shoe front.

The tests carried out on a sheep skin sample after processing it according to the present invention (sample A) and on a raw sheep skin sample (B) are as follows: the tensile and elongation strengths are determined; determine tear resistance, op-

7760812

The resistance of the skin face to stretching and tearing is determined by a spherical method, wear resistance is determined by repeated continuous bending of light skin and its surface sizing.

Sample A (processed according to the invention). Standard procedure: SE UNI ISO 3376 - Determination of tensile and tensile strength.

Samples, possibly prepared in accordance with established standards, experience tensile stresses 15 to failure on the tensile testing apparatus. Tensile strength is obtained by dividing the breaking load by the cross-sectional area of the sample and is expressed in terms of

N / MM2.

Ultimate elongation is calculated from the difference between the initial length of the sample and its final length. This difference is expressed as a percentage of the initial length of the sample.

Preparation and testing: normal atmosphere, type Al (20 ± 2 ° C, 65 relative humidity).

30 - ONI ISO 2589 - mechanical testing of the skin - determination of thickness. Sample Resistance Tensile strength (N / mm2) elongation,%

111.4 39.4

212.35 42.2 3 12.52 44.0

The average tensile strength is 12.1.

The average value of the ultimate elongation is 40 days 41.88.

The standard method of UNI ISO 3377 IUP 8 is the determination of tensile strength.

25

35

A rectangular specimen, in which a slot of a certain shape was made, was hung on the protruding ends of a pair of specimen holders secured between the clamps of the test device on

tear resistance. The maximum elongation load required to separate the sample holders is considered to be the tensile strength.

Preparation and testing: ordinary atmosphere, type A2 (23i2 ° C, 50 ± 52 relative humidity).

Pulling speed: 100 ± ± 10 mm / min

131777608

Tensile Strength (N / mm2) 51.6

Mt 5

B 2,3

The average value of the tensile strength A6,12

The standard method of UNI ISO 3379 10 is to determine the resistance to tearing and tearing of the face of a skin - ball method.

Sample

The load at which a crack is formed (N) The cracking strength (mm) The tensile strength

(H)

Stretch at break (mm)

The average load for cracking: The average tensile strength at cracking: The average tensile load (N) The average tensile strength at break:

Standard method: UNI 8433 / TUP 20 - determination of the resistance to repeated application of the load (continuous storage) of light skin and skin sizing.

This is carried out by attaching each sample to two clamps of the test device.

One of the two clamps is stationary, while the other is forced to oscillate with an amplitude of 22.5 ° at a frequency of 100 + 5 cycles / minute, while it carries a rolled sample.

Preparation and testing: typical atmosphere is A1 type / 200 + 2 ° С 65 + 5% relative humidity.

By cutting, 6 rectangular samples of a size of mm were obtained. Number of test cycles: 50,000

40

45

fifty

tests of no cracks worsen its quality

A steel ball is received to the central part of the medial side of the sample, a skin cut in the shape of a disk, which is firmly attached along its peripheral part.

The force of the ball and the subsequent stretching of the sample are recorded at the moment when the skin face is cracked and skin rupture occurs (possible).

Preparation and testing:

The atmosphere is typical, A1 type (20 ± 2 ° 65 ± 5S U.R.).

23

230.6 n

5.8 mm 558.6

35

8.3 mm

Sample B (untreated sample

Standard Method: UNI ISO 3376

- determination of tensile strength and elongation.

After their preparation, the samples experience a tensile stress of up to 40 damage on the tensile testing machine.

Tear resistance is measured by dividing the ultimate load at break by the cross-sectional area of the sample and is expressed as a value.

Ultimate elongation is obtained by calculating the difference between the initial length of the sample and its final 50 length. This difference is expressed as a percentage of the initial length of the sample.

Preparation and testing: a typical atmosphere of type A1 (20 ± 2 ° C 6515% relative humidity 55).

- UNl ISO 2589 - Leather - Mechanical testing - Determination of thickness.

151777608

Sample Tensile Strength - Tear (N / mm2) shedding,%

121.28 60.6

219.7 6.8 5

3. 15.96 L6.6 Average tensile strength 18.97

Ultimate Elongation 51.0 Standard UNI ISO 3377 IUP 1Q method - Determination of tensile strength. A rectangular specimen in which a slit of a specific shape has been cut is suspended on the protruding ends of a pair of specimen holders attached between the clamps of a tensile testing machine. The tensile strength is considered the maximum elongation load required to separate the sample holders. Preparation and testing:

sixteen

) Average tensile at break: 9.5 mm

The standard method of UNI 8A33 / IUP 2Q is the determination of the resistance to repeated application of the load (which consists in repeated continuous folding) of light skin and surface sizing of the skin.

This determination is made by attaching each sample to two clamps of the test device

One of the two clamps is stationary, while the other is forced to oscillate with an amplitude of 22.5 ° at a frequency of 100 ± 5 cycles / min, and it carries a sample of folded skin.

Preparation and testing: Typical 20 atmosphere type A1 (20 ° ± 2 ° C b5 ± 5% from 15

A typical atmosphere of type A2 (23 ± 2 ° C 50 ± 5% relative humidity).

Extraction rate: 100 ± mm / min. Sample Tear resistance (N / mm2)

173.1

268.6

36 / 4.1 Average tear resistance

68.6.

The standard method of UNI ISO 3379 is to determine the tensile strength and tear resistance of a skin face - the ball method.

A steel ball is pressed against the central part of the medial side of a skin sample cut out in the shape of a disk and firmly fixed along its peripheral part.

The force of the steel ball and the stretching of the sample are recorded at the moment when the skin face is cracked and rupture occurs (possibly);

Preparation and testing: a typical atmosphere of type A1 (10 ± 2 ° C, 65i5% relative humidity).

25

thirty

relative humidity).

By cutting, 6 rectangular samples of size 70 to 45 mm were prepared.

Number of test cycles 50,000 cycles.

At the end of the test, the samples did not show the formation of any cracks or other signs of deterioration in skin quality.

The following table summarizes the results of the mentioned process tests.

From such a table it can be seen that the values obtained for sample A are not only better than the results obtained for sheep leather intended for the manufacture of shoe front, but also better than the results for lamb leather.

The present invention has been described with reference to its particular embodiments, but it is clear that modifications and variations are possible within the scope of the invention.

35

45

F

Sample

The load at which cracks form (N)

Cracking Resistance (mm) Load at Break (N)

Stretch at break (mm)

The average load at break: 528.6

claims

123 Method for treating the skin for the front end

shoes, including soaking, fading, 5Q washing, pickling, tanning,

acid removal, retanning, drying, sizing, punching and subsequent finishing, characterized in that, for the purpose of

510.0 589.0 478.0g improving the quality of the skin, after retanning it is neutralized for 1 h to a pH of 6, treated with acrylic

10.5 9.2 9.0

ether in an amount of 7 g / l at 50 ° C for 0 h and

5

Q

sixteen

) Average tensile at break: 9.5 mm

The standard method of UNI 8A33 / IUP 2Q is to determine the resistance to repeated application of the load (which consists in repeated continuous folding) of light skin and skin sizing.

This determination is made by attaching each sample to two clamps of the test device.

One of the two clamps is stationary, while the other is forced to oscillate with an amplitude of 22.5 ° at a frequency of 100 ± 5 cycles / min, and it carries a sample of folded skin.

Preparation and testing: typical 0 atmosphere type A1 (20 ° ± 2 ° C b5 ± 5% of

relative humidity).

By cutting, 6 rectangular samples of size 70 to 45 mm were prepared.

Number of test cycles 50,000 cycles.

At the end of the test, the samples did not show the formation of any cracks or other signs of deterioration in skin quality.

The following table summarizes the results of the mentioned process tests.

From such a table it can be seen that the values obtained for sample A are not only better than the results obtained for sheep leather intended for the manufacture of shoe front, but also better than the results for sheep skin.

The present invention has been described with reference to its particular embodiments, but it is clear that modifications and variations are possible within the scope of the invention.

ether in an amount of 7 g / l at 50 C for 0 h and ak171 is polymerized

ryl ether with formic acid, after drying, the skin is treated under a pressure of 20 kg / cm2 at a temperature of 100-120 ° C for A-8 s, and after punching the holes, the skin is treated

8

eighteen

a solution of methacrylic resin in an amount of k-b g / l at 50-60 ° C and for yO-kS min the resin is polymerized by the addition of formic acid.

FIG. 2