FINISHING TYPES

FINISHING TYPES

Finishing types: Finishing types are named according to the binders (binder) used, according to the finishing technique and the appearance of the skin.

Grouping by binder

Casein finishing: Casein is used as binder. Casein is obtained by precipitating from skim milk with acid. Today, casein produced with less odorous salt acid is used. To improve casein finishing, softener, wax, natural and synthetic resin are used together. Caffeine is modified with polyamide-forming (caprolactam, polycarboxylic acid) substances. To color the casein finishing, fine-grained pygmens or non-brimy watery-pygmene dispersions containing casein are used, inorganic pigs cover finishing, transparent finishing with organic pigments. Water-soluble proteins are not water resistant after drying. It is fixed with formaldehyde-chromium salt solution for water resistance. Finishing with non-thermoplastic protein is particularly suitable for finishing.

It can be applied by ironing casein finishing on leather with a soft-lining lining and shoes (upper). Finishing agent is applied with a sponge and velvet to achieve high gloss in casein finishing.

Binder finishing: Binder alone without the use of other film-forming substances.

The finishing done is no longer abundant. Removal on a thermo-plastic filling layer (foli printing) on ​​a thick thermoplastic filling layer on split leather, thermoplastic binder is used alone in the finishing, which gives a patent leather effect on the sanded bovine skin.

Combined methods are applied in modern binder finishing. In these combinations, non-thermoplastic protein-based substances nitrocellulose emulsions or polyurethane dispersions (in paint and leveling coat) and protein-nitrocellulose- or polyurethane finishing agents are used. Another possibility is to use reactive binders. These polymerizers dispersions containing reactive groups form salt with very valuable metal ions during drying on the skin surface, creating a high water resistance. In Binder finishing, hot ironing and pressing are applied.

Nitro cellulose (collodion) finishing: Nitro cellulose finishing, which forms a thin layer on the leather surface, gains importance in the production of glazed leather. Usually applied with dispersion binders, nitro cellulose is applied on the solid layer and combined finishing is done. The non-thermoplastic hard nitro cellulose film is made to some extent flexible with the addition of a softener. As the nitro cellulose film is not soft enough, it is less resistant to bending but forms a good protective layer against friction and scraping. metal complex paints are used primarily due to high light fastness. If the nitro cellulose solution is applied in thin layers with a gun (compared to using more than one substance at a time), it creates a more flexible film.

Polyurethane finishing: The latest development in binding agents (binder) for leather finishing is polyurethane. Poly urethane are large molecule addition compounds consisting of polyether, polyester, partial ether or esterified polyalcohols (soft component) and hardener and molecule enhancer aliphatic or aromatic polyisocionates. Polyurethane compounds with different hardness, flexibility, friction and bending properties are obtained depending on the ratio and reaction type of the selected materials. When applied in a thick layer in a curtain machine with pouring or gun (airless-pressurized), a glossy film with the appearance of patent leather is obtained. The friction fastness, bending fastness and solvent resistance of this film layer is very high.

Polyurethane emulsions and dispersions can be used as a glaze fixer and filler in the filler layer in glaze and sanded leather in the paint layer and in the finishing layer. It can dry and harden in the environment temparature. The finishing layer is ironed at 80 degrees. Printing and final ironing is done at 100 oC.

GROUPING BY FINISHING TECHNIQUE

Finishing finish: The finishing finish is based on the smoothing and polishing of the leather surface under pressure by rubbing. The process is done with the finishing machine. Non-thermoplastic binders are suitable for this finishing, as heat is produced by rubbing motion. Casein is applied to form a thin layer. The glaze of the leather to be finished should be tightly structured. Capricorn and calf leather are suitable for this finishing. Finishing is done for reptile animal skins. The finishing finishing addresses the aesthetic and fashion aspect of the leather as it makes the natural appearance of the leather more noticeable.

Iron finishing: In the iron finishing, the leather is subjected to heat and pressure treatment. Contrary to the finishing finish, the pressure is distributed over a large surface. The surface of the skin is less transparent, appears less noticeable, the gloss is less, homogeneity is better. Thermo plastic binder should be used in ironing finishing. With the effect of heat and pressure, the thermoplastic binder softens and takes shape in the direction of pressure. In this way, a homogeneous smooth and shiny surface is formed. The fibrous surface of the split and sanded leather is made a layer with polymerizer binder, making it fuller and firmer. In order to obtain a homogeneous and smooth surface, the skin is ironed after the filling and paint layer, ironed again after the finishing layer. Three factors act together in press ironing and pattern. These are pressure, temparature and pressing time. Both factors balance the third.

Finishing iron finishing: This finishing combination is applied for large calf skins and cattle skins. Filling layer is applied to the leather with a binder that is thermoplastic and polishing is done. Then ironing is done after the paint coat containing the thermoplastic binder and the finish coat.

Velvet or brush finishing: In this application, the finishing float is applied on the leather surface with a soft brush or velvet. A homogeneous dispersion and a film tightly attached to the skin are obtained. Using a large amount of material, a thick finishing layer can be applied. This method is generally used in the application of filling layers with polymerizate binders. In the skin of the skin, a hard brush is used. Velvet is used in sanded cowhide. This method is not applied alone. The leather, which is filled with velvet or brush, is dried, and after finishing ironing, gun finishing is applied.

Gun finishing: in this method, the finishing float is sprayed with a pressure from the small hole (nozzle) into the surface of the skin in small particles. In this way, a homogeneous distribution is provided, the amount of the substance used can be precisely adjusted. If the surface of the skin is not too absorbent, if the polymer dispersion is of low viscosity or diluted organic solution is used, a homogeneous film is obtained. A good film is not provided with sudden drying solutions at high viscosity. This method is generally applied in light finishing and thin finishing coats or in the upper layers of the finishing applied in thin layer.

Pouring (curtain) finishing: In this system, the finishing float flows in the form of a curtain from a chamber located at the top of the opening between the bands, which moves horizontally on the pushing and pulling belt with a gap between them. The finishing float flowing in the form of a curtain is transferred to the leather surface while moving horizontally on the leather band. This technique is suitable for applying a large amount of material to the leather surface. Bulk (curtain) finishing can be applied to heavy skins with smooth surfaces. It is not suitable for working with this method since thin and light skins are folded during the process.

Printing finishing: Different patterns can be created on the leather surface with the help of patterned printing rollers. By means of a leather transfer tape, the paint printing roller on top is passed through the printing machine with an attractive press roller at the bottom and the pattern in the paint printing roller is applied to the leather surface.

Foam coating: It is a special form of finishing developed for split leathers. Polymerizer dispersions are used with foaming agents. The substance, which is degraded by the effect of heat, forms a porous foam layer on the skin surface by making foam and this layer is corrected by pressing. Pattern can be given by pressing. In this way, it is used as an accessory in leather products by creating letter and pattern patterns on the leather surface.

Foli coating: A finishing technique applied by sticking foli on the leather surface for special purposes.

It is adhered to the porous leather surface with a porous or tightly structured polyvinylchloride. In this way, by creating a letter and a pattern badge on the leather surface, it is used as an accessory in leather products. This layer, which is covered with split leather, is more sanitary because it has air and water vapor permeability.

GROUPING BY VIEW

Covering finish: It is a finish applied by covering the leather surface with a homogeneous, thick finishing layer. This finishing is applied especially on split leather and sanded leather. Superficial and deep sanding is done in cattle leathers to remove glaze defects. The leather surface, which has been made homogeneous with this process, has a fibrous structure. In this way, the surface of the split leather with sanded leather is covered with dispersion polymerizers containing highly inorganic pygments. Covering finishing glaze is applied to faulty leathers. Due to the gradually decreasing market demand for shooter finishing, the use of such finished leather is limited for work shoes, safety shoes (safety) sports shoes and some sarraciye products.

Analin finishing: In the finishing of the aniline, the natural appearance of the skin surface is preserved, and the grain structure becomes more evident in light and dark shades. Finishing consists of transparent paint and finish (varnish) on glazed leather. The leather is painted before finishing.

Semi-anal finishing: A form of finishing between the covering finish and the finishing appearance of the anal. The finishing of the anal is generally slightly sanded and the glaze structure is smoothed.

applied on leathers. A more or less paint covering coat is applied over a glaze fixing filler layer. The surface is made homogeneous with ironing or press pattern printing. A colorless or colored finish layer is applied. A better appearance is applied by applying a darker layer of paint on a light background, as in the finish of the analine.

Lacquer finish: It is the form of finishing where the surface of the skin is covered with a thick (0.1-02 mm) lacquer layer. With this finish, the natural appearance of the skin and the characteristic skin attitude disappear. Very smooth high gloss, plastic attitude and appearance leather is obtained. In lacquer finishing, effects ranging from the appearance of the transparent anal to the shooter finish can be obtained by painting. Characteristically, the appearance is a pigmentless, colored or colorless glossy appearance. In order to provide high gloss and vitality in lacquered leather (patent leather), the filling layer is strongly pigmented, and the lacquer layer is applied transparently. Differently, a thick lacquer film should be created in the finishing (polish) layer.

Posted by: İrfan GÜNGÖR at 00:51 0 comments Links to the Post:

Keywords: leather, finishing

Sunday, July 29, 2007

CATIONIC FINISH

Today, finishing technology shows a constantly evolving situation. However, until recently, these innovations were constantly anionic in chemical product level.

PIELCOLOR SA, one of the world leaders in leather finishing, has added a new finishing variety and technology in accordance with the conditions of the day, which it has frequently developed and introduced to the world market.

Cationic products for finishing:

How is the cationic structure of finishing products explained?

Some products do not have a cationic structure, but cationic properties are provided by the addition of auxiliary additives. However, depending on their anionic or cationic structure, products that do not melt or ionize are mentioned, not products that can dissolve in the form of emulsions or dispersions:

Dispersions Example: Pigments

Example of Emulations: Waxes

Solution Example: Some proteins

In all these cases, cationic structure is gained by using dispersion, emulsion or solution obtained by some auxiliary additives. In contrast, a group of products have their own cationic structure. Here we are talking about regulators, stabilizers, penetrators and especially acrylic or urethane polymers, since they are generally used in anionic (or non-ionic) radicals whose molecules have been damaged by alteration have changed their ionic structure.

A recent past

There were cationic products that have been used for many years with a specific purpose and not much use other than the touch layer. These did not go beyond some polymers and waxes, but they did not have much use. Strangely enough, they used it as the first and last layer. Pigments, which have some features due to their characteristic structure, started to emerge afterwards, which were not only in demand for very special uses.

Some technicians were looking for ways to tackle the challenges and problems created by these classic products. We have slowly discovered that there is a world hidden behind this cationic. There was a need to improve the existing product and create new products. However, it should be known that the classical system is not taken as a model for the cationic system.

Why not a new technique and a new philosophy?

The new technique and way of thinking might not be interesting for some. In contrast, it has come to provide unrivaled advantages for some. This situation has led us to develop a complete product range such as pigments, oils, waxes, filling materials, proteins, binders.

Behaviour

Truth be told, it is necessary to know what the "cationic finishing" is rather than "how". Although it knows the results of cationic finishing, there is no information about the mechanism of operation. Generally, we can say that for many skins, the superficial anionic character of the skins is caused by wetting due to finishing. Since this application is cationic, the finish is bound to the skin with a high affinity in its cationic chemical nature. Thus, it can be said that the connection problem will disappear. Therefore, the skins can be covered with a small film thickness before they harden, as well as a homogeneous and natural attitude and some fastnesses are obtained. These can be counted as advantages over conventional finishing.

One hour after the cationic applications made of leathers without good penetration, a leather that is sensitive to environmental conditions, but soft, slightly sticky, weak against friction, and not resistant to mechanical conditions (polishing, glaze, dry cabinet) is obtained. In addition, overcharging or very hot press applications can cause problems in the connections of the floors that will come afterwards. All these situations can be disappointing. However, these should be perceived as a warning. However, if such finishes are allowed to rest for 24–28 hours, the disadvantages just mentioned are eliminated. The initial reactions to the cationic finishing were due to insecurity arising from endurance. Today, this insecurity has now been overcome. The same expectations from anionic finishing are also expected from the cationic finishing. As an example, we can show washable leathers made with cationic finishing. nonetheless, it is important not to give up anionic finishes that contain specific leathers (polyacrylline etc.) where high performance is expected.

Warnings

A number of issues were mentioned as a warning above. As everyone knows, cationic and anionic products are incompatible. Therefore, the machinery and equipment (pistole, pump, mixers etc.) used in the application must be cleaned very well when changing the system.

formulations

Unlike the preparation of anionic solutions used to date, the preparation of cationic mixtures is quite different. In cationic finishing, a solution is prepared taking into account the special behavior of three main products (pigments, binders, auxiliary products).

* Pigments: Due to the high performance of cationic pigments, 50 gr per liter cannot be exceeded regardless of the desired hiding degree. This causes the cationic finish to be more natural and pleasant due to the use of less pigment, as a covering.

* Binders: Due to the use of low pigment, the binder is used less accordingly. (Approximately 40 gr \ lt) Thus, using the plastics encourages a more natural and light skin.

* Auxiliaries: Soft and hard waxes, oils, proteins, opacifiers, fillers, silicones are important finishing products. (These products are softer in nature than anionics). Depending on the anionic finish, the auxiliary products to be used depending on the amount are used less in terms of quantity. The ratio of the mixes to be used on the main floor is 250-300 gr / lt. In addition, the use of products such as penetrators, emitters is as much as in anionic systems.

About the economy

Cationics are more expensive in kg compared to conventional products. However, when using cationic or "cationic + anionic" combination, more economic results are obtained. It should not be forgotten that the cationic system not only improves the quality, but also provides monetary gains in terms of easily closing the skin of the skin and improving the asortization. This result is achieved by the lower costs per square foot. If we give a specific example; Let's finish two raw nappa leather with a classic pigmented finish and “cationic + anionic” finish. If we make a comparison in terms of price (average values);

Classic Cationic

Pigments 3 9

Helpers 2 3

Acrylic 2 3

Urethane 4 6

Let's do cost analysis per liter for both systems.

Gram Classic Product Amount Gram Cationic Amount

Prices First floor price

Pigments 100 3 300 50 9 450

Auxiliaries 200 2 400 350 3 1050

Acrylics 200 2 400 125 3 375

Urethanes 100 4 400 100 6 600

Water 400 - - 375 - -

Total 1000 (1) 1500 1000 (2) 2475

Gram Classic paint prices Amount

Pigments 50 3 150

Auxiliaries 2 450 900

Acrylics 100 2 200

Urethanes 100 4 400

Water 525 - -

Total 1000 (3) 1200

Cost for each group: (1) = 1.5, (2) = 2.475, (3) = 1.2

Consumption: 6 grams per square (6 g / a2)

Cost for each foot:

Classical system: 8 layers X 6 = 48 X 1.5 (1) = 72 72

Combined system: 2 layers X 6 = 12 X 2.475 (2) = 29.7

4 layers X 6 = 24 X 1.2 (3) = 28.8 58.5

As can be seen, there is an important difference. This difference has an important level of competence to eliminate mistakes. In addition, it should not be overlooked that, while covering the faults, the quality increases with the assortment of the skin.

When cationic finishing

As we explained earlier, the cationic finish does not always respond to everything. Below are listed in which cases it will be used. The leathers in the list are full-skinned leathers.

a) High quality leathers; Advantages: Color, attitude and shine give higher finish leather and naturalness with less finishing. (Full cationic finishing will be appropriate.)

b) Raw leathers; Advantages: It covers skin faults with high efficiency with very little finishing. It helps in maintaining quality and price assortment. It helps in maintaining quality and price. (full cationic or combined anionic + cationic)

c) Leathers with connection problems; It is mostly applied when:

· In waterproof leathers made in sub-process

· Wax or wax-oil for the first applied leather

(A cationic pre-application will suffice.)

d) Hides (pigmented) requiring covering; Advantages: It provides better breakage, naturalness and price protection with less finishing thickness. (a combined finish)

Result

We are sure that cationic finishing will not be an end in leather finishing. In this regard, it will be very difficult to predict where technology will arrive. It is for this reason that all research and studies continue in this direction.