CS215771B1 - Method of making shoes - Google Patents

Abstract

•'Method of producing footwear' The invention addresses the issue of producing uppers of spatially formed footwear from polymer solutions, which replaces conventionally produced footwear from cut sheets of sheet materials, especially leather and its substitutes. The purpose of the invention is to achieve a more perfect appearance of the surface treatment, especially with regard to the imitation of the surface pattern of natural leather and in the imitation of sewing seams, which are characteristic features of classic types of footwear made of upper leather, which are still the most highly valued. The stated purpose is achieved by providing a negative pattern to a hoof-shaped form, on which individual layers of polymer solutions are gradually applied, and on which a layer is first applied to create the outer surface of the finished footwear, and after the remaining layers have been applied, the resulting upper is covered with the outer surface inwards after being removed from the hoof. Polymers containing polyethylene glycol with a relative molecular weight 600 to δδδδ.

Description

The present invention relates to a process for the manufacture of footwear, in particular of its upper part, by three-dimensional molding of polymer solutions, in particular of polyurethane solutions in dimethylformamide, in which the upper is formed by successively applying individual layers of polymer solutions to the hoof form. a reinforcing layer of textile material is interposed between these layers of polymer solutions.

The manufacture of footwear, and in particular the preparation of footwear uppers, is, with some exceptions, still very conservative and uses essentially the same principles; the raw materials, ie natural or synthetic leather, are flat materials and must be processed by punching, sewing, gluing, stretching and biting on the spatially shaped shoe parts and on the shoe parts. This method of manufacture is very laborious and, therefore, attempts have been made to find other methods that would eliminate the complexity and laboriousness of manufacturing footwear from flat materials. For example, the shoe product has been solved by casting from polyvinyl chloride pastes in which it is poured into a metal gelatin mold, pregelatinizes on the walls, excess paste is poured out and the upper part gelatinizes at the required temperature. Another simple manufacturing process is the manufacture of rubber shin shoes by dipping them into thermosensible or other latexes, or the manufacture of shoes by injection molding polymeric materials into molds. However, all of these manufacturing processes lead to footwear which is not capable of passing water vapor and, consequently, does not have the most inherent hygienic properties; the processes are therefore only suitable for the production of purpose-built footwear, such as for fishermen or rain boots.

Possibilities of production of surface polymers by precipitation of polyurethane solutions from dimethylformamide with water, opened the possibilities of application of polymers also in the production of shoe uppers. For example, a manufacturing process has been proposed in which a microporous mold of sintered synthetic material is used and a layer of a poromer is formed in a single operation, the increase in water permeability being achieved by the use of finely ground sodium chloride. In practice, however, there are considerable problems with this manufacturing process, for example in the manufacture of sintered molds which are unable to maintain the desired deenene quality and sewing. Also, the diffusion of dimatylformamide over the pores of the sintered form proceeds very slowly and is negligible by practitioners compared to the diffusion in the direction of the precipitant, so that only inferior surfaces are achieved by using this type of mold. In addition, the upper blanks prepared by the precipitation of a single layer of polyurethane solution applied to the mold are poorly resistant to further tearing at the points where the upper parts had to be cut in terms of shoe construction and manufacturing technology. Another manufacturing method is described in the disclosure of U.S. Patent No. 3,642,966. This manufacturing process assumes that a layer of fibrous material, preferably knitted fabric having a certain moisture content, is stretched onto the foot or hoof, and the foot or hoof so treated is immersed in a solution of polyurethane in dimethylformamide. Upon removal of the foot from the solution, the polyurethane deposit is precipitated in water with varying dimethylformamide content, thereby providing a hoof-like blank with a micro-porous structure capable of passing water vapor. The advantage of this manufacturing process is that it is easy to achieve thicknesses of 1.2 to 1.7 mm in one dipping operation and longer the surface quality of the precipitated poromer, but the precipitated microporous layer is smooth and has yet to be re-designed. The tread blank is carried out in heated molds with the necessary pressure and, on the one hand, compresses the microcellular structure and reduces the water vapor permeability, and on the other hand the designs do not have the desired fidelity, especially as regards sewing. This is not the production method. it is possible to imitate a layer of material, which is to say stacking several pieces of leather. A major defect is the dividing plane in the press mold, as it is almost always apparent on the produced footwear, thus reducing the aesthetic appearance of the product.

A method of making a footwear, in particular an upper part thereof, by spatially forming solutions of urethane poles in dimethylformamide, in which the uppers are formed by successively applying individual layers of polymeric solutions to the hoof-shaped mold, optionally including a reinforced layer between them. The textile material differs from the above-mentioned processes in terms of practical feasibility and high convincing appearance of the manufactured products, which are almost indistinguishable from the classic made uppers. According to the invention the essence of this method is that provided with a negative design, the first layer forming the outer surface of the shoe is applied to the finished shoe, and after depositing the remaining layers, the resulting upper is changed to the outer surface after removal from the hoof. The advantages of the present invention multiply when formed into the polymer solution. For example, polymers containing polyethylene glycol with a molecular weight of 600 - 6000 are added.

The technical effect of the method according to the invention must be observed in that the upper of the produced shoe has not only the appearance, but also the properties of the upper prepared by the classical method of sewing from natural leather. The design of the upper and, in particular, the imitation of sewing is absolutely perfect and does not require additional pressing adjustments.

Said and possibly further advantages of the process according to the invention will become apparent from the following description.

The semi-finished upper product is produced by depositing polymer solutions with a hoof provided with a negative design of the upper material and sewing. The actual upper part is produced in several successive operations from solutions of polyurethane polymers, whether or not dyed, which solutions are treated by the addition of surfactants, fillers such as silica and calcium carbonate, or by means of secondary solvents such as mono and hydroxy derivatives of aliphatic hydrocarbons or monoezers of ethylene glycol. To increase the permeability, ammonium sulphate in finely ground form can be added, and to shorten the precipitation time a certain amount of water is usually added, as a rule 1 to 7 percent as pre-precipitants. The production process consists in that a layer of a linear polyurethane solution is applied to the dry mold, and it is preferable to use an aliphatic polyurethane in view of the required lightfastness of the material and the color fastness. The choice of solvent for this layer, whose thickness is in the range 0.05 to 0.2 mm, is not critical, since the coating of the linear polyurethane is dried before further processing and the subsequent layers are already applied to the dried layer. The linear polyurethane layer forms the top face layer; shoes. Its ability to flow into the sewing and fine pores of the tread guarantees the production of semi-finished products with perfect surfaces, ie perfect sewing of leather shoes.

A further manufacturing process consists in applying a layer of polyurethane in a solution of dimethylformamide. This layer can be deposited by spraying, dipping or pouring, it being important that the thickness of the layer does not exceed 1.5 mm with respect to the future desired microstructure of the layer. Therefore, spraying, which ensures a uniform layer thickness over the entire surface of the mold, seems more suitable. The viscosity of the applied solutions ranges from 6 to 20 Pas. Solutions of lower viscosities have a high tendency to run off the mold and are only applicable to very thin layers of material. Solutions with high viscosity values above 25 waist will poorly flow and lead to considerable differences in thickness. Spraying is best suited for applying a solution of polyurethane in dimethylformamide to the mold. Due to the low volatility of dimethylformamide, it is possible to work on a drift-retarding device, thereby avoiding the losses that are common in spraying processes. By spraying it is possible to adjust the thickness of the deposited layer in individual places of the mold continuously without sudden changes, which is practically impossible in other processes. If soaking is used, the manufacturing process consists in dipping the linear polyurethane, preferably aliphatic, mold into a bath of a solution of polyurethane in dimethylformamide, with viscosities in the range of 6 to 25 Pas. Upon removal from the solution, the mold is generally slid from heel to toe and, after emerging above the surface of the dipping bath, is turned upward. The mold movements and individual velocities are adjusted to obtain a uniform layer over the entire surface. In order to better distribute the polyurethane solution and thereby achieve a uniform deposition, the thickness of the layer can be adjusted in the individual mold parts by blowing compressed air. The mold with the deposited modified polyv urethane solution, which will form a facing layer on the finished shoe upper, then enters the pre-precipitation chamber, in which the base layer is pre-precipitated by the action of the supersaturated water vapor atmosphere. Pre-chamfering is necessary in order to achieve perfect reproduction of the design and sewing and a high-quality micro-porous structure in the layer cut and thus good water vapor permeability and last but not least strength parameters, especially in those cases where the reverse layer of linear polyurethane is not used. Pre-precipitation with water vapor can also be replaced by other methods which allow the diffusion of water into the polymer solution at a reduced rate of diffusion of dimatyl fluoroside in solution onto the mold into the precipitation bath. An example is pre-precipitation in water baths containing at least 30% dimethylformamide, but usually in the range of 50-75%.

2Ů5771

Pre-shrinking should reduce the rate of dimethylformamide scrubbing from the precipitated layer during pre-shrinking, thereby avoiding the formation of a relatively compact layer on the precipitated solution towards the precipitant. In cases where this compact layer is formed, the time required for precipitation of the solution is prolonged and uneven structures are formed, the porosity of which increases towards the mold wall. Subsequently, this layer acts to reduce the permeability and reduce the mechanical as well as utility properties of the produced footwear.

After a pre-shrinking operation, which is not necessarily an operation, although it may favorably affect in particular the productivity of the production equipment and the surface quality of the manufactured blanks, the molds with a pre-punched material layer are transferred to the precipitation and wash baths. It is a system of several baths with different content of dimethylformamide, its variable content is given mainly by the speed of diffusion of dimethylformamide into precipitation and wash baths. It has been found that the most preferred bath concentrations are 25 to 35% for the first bath, 10 to 20% for the second bath, 5 to 15% for the third bath and water in the fourth bath.

It is advantageous to control the mode of the production line technologically so that virtually all the water entering the scrubbing section of the line falls off in the precipitation portion in the form of a 30% solution, from which the dimethylformaaid is recovered by distillation. The rate of scrubbing can be substantially reduced by increasing the temperature of the individual baths, as determined from 15 to 65 ° C. In addition to the beneficial effect of shortening the precipitation and scrubbing times, the temperature increase has a negative impact on the dimethylamine increased evaporation of dimethylformamide and its increased hydrolysis. Increased evaporation and hydrolysis cause an increased risk of highly toxic pollutants.

For this reason, it is preferable to operate at 20-25 ° C. After the first layer of the polymer solution has precipitated, the precipitated layer mold is removed from the precipitation bath and dried with a stream of air, and it is advantageous to rinse the adhering layer of water with a volatile solvent to accelerate drying.

After drying, a layer of reinforcing fabric is stretched onto the mold, which is usually a knitted fabric, guaranteeing a perfect encirclement of the mold. The mold with the precipitated first layer on which the reinforcing fabric is stretched is then soaked in a dilute polyurethane solution in dimethylformamide. The viscosity in the solution is in the range of 0.2 to 4 Pas, at a dry weight of 5 to 20%. Low viscosity is necessary to allow perfect wetting of the fabric stretched on the mold and to prevent air bubbles from closing in the space between the fabric and the precipitated substrate. relative layer. After removal of the mold from the dipping solution for the backing layer, the solution is precipitated in precipitation tubs, similar to the first layer. Since the backing polymer flows into the interstice in the knitted fabric, its viscosity can vary widely, which is particularly important for low viscosities which provide comparative layers with considerable water vapor permeability, thereby allowing water vapor access to the fabric, which, thanks to its sorbent properties, increases the pleasant feeling of wearing footwear from such prepared blanks. The textile layer, which is anchored after the reverse low viscosity solution is anchored to the notch relative layer, serves both as a reinforcing material which increases the tear resistance and the resistance of the upper piece against further tearing; The hygienic properties of the footwear, in particular the water sorption, are favorably influenced by the suitable composition of the textile, so that the footwear produced is close to the footwear made of leather materials. For example, the use of cotton or cotton blended fabrics will significantly improve the hygiene properties of the upper blanks.

The composition of the polymer solutions for the preparation of both layers can be varied within a wide range.

For the first layer to be applied to the coating composition, more viscous solutions are used with the addition of up to 5% non-ionic detergent and 1 to 5% water. In addition, it is suitable to use solutions with the addition of inorganic fillers such as calcium or magnesium carbonate, silica or precipitated bentonite. The fillers favorably affect the viscosity in that they prevent the polymer from flowing down the walls of the mold and the formation of considerable thickness differences between the individual locations on the blank. In addition, the bird prevents the collapse of the preform microstructure, which occurs when unfilled systems are used in the inadequate washing of preforms with residual proportions of dimethylformamide, when drying; as a result of solvent concentration after evaporation of the water.

The backing layer is applied to the facing layer after stretching the reinforcing fabric and is formed by applying a viscosity solution ensuring easy flowing of the polymeric textile solution and perfect bonding of the backing layer to the facing layer. The viscosity of the back solutions ranges from 0.2 to Pas, while the dry matter content of the solution is from 5 to 20%. Since the backsheet must not interfere with the porous cheek layer, it is expedient to add a secondary solvent to the facing layer to suppress the tendency of the backsheet solvent system to dissolve the microporous cheek layer while preventing the polymer from precipitating out of solution.

Typical examples of these secondary solvents are: ethyl alcohol, ethylene glycol, propyl alcohol, ethylene glycol, di and triethylene glycol, glycerin, propylene glycol or butylene glycol. The use of the diluent addition depends on the method of applying the backing layer, in particular the degree of drying of the first layer, the time of immersion of the mold in the backing solution and the temperature of the backing solution. In the process according to the invention, the drying must be adapted so that on the surface of the first microporous layer there is a thin, dry layer under which the remaining layer of material is saturated with a dimethylformamide-containing aqueous phase. As mentioned above, this is most easily accomplished if the drying is carried out with a stream of air, optionally heated to higher temperatures, or by rinsing with a water-miscible low boiling solvent followed by drying with a stream of dry air.

Depending on the degree of dilution of the reverse solution, the hygienic properties of the entire semi-finished product, in particular the water vapor sorption and the overall elasticity of the scratch panel, are dependent. As the dry matter content of the solution decreases, the water vapor permeability of the microporous layer increases. This makes it easier for water vapor to penetrate into the textile layer, where it is partially absorbed. As the dry matter content of the solution decreases, the thickness of the individual cell walls of the plated poromer decreases and, as a result, the elasticity of the panel increases and the modulus at elongation decreases. It is therefore expedient to use solutions with a dry matter content of 10 to 15%. Solutions with a lower dry matter content flow very well through the textile layer, but their structural strength is very low. At higher dry matter values, air bubbles build up in the fabric layer structure. ,

After the individual layers have been applied to the mold and after they have been pierced in a water bath, the blanks are stripped from the mold and subjected to further washing of residual dimethylformamide. It is preferable to perform scrubbing in drum washing machines, but tubs with scrubbing water movement can be used. The time depends on the washing conditions and the temperature of the washing water. The time required to wash the preforms in a drum washer is 2 to 4 hours at 20 ° C and 1 to 2 hours at a temperature ranging from 60 to 80 ° C.

The washed upper blanks are then dried on the hooves at temperatures of 120 to 145 ° C for 20 to 30 minutes, after which the stabilizing hooves are transferred to the assembly shop after withdrawal. The uppers produced according to the method of the invention are perfectly similar in appearance to footwear produced by conventional sewing technology from flat materials. The hygienic properties are 2 very good, the water vapor permeability ranges from 4 to 8 mg / cm h.

The method according to the invention is supplemented by several exemplary embodiments.

Example 1

A / Preparation of the polymer base solution.

a) By introducing the components into a stirred reactor, a solution is prepared by reacting 10 kg of polybutylene adipate of molecular weight 2000 (OH number 56) with 7.5 kg of diphenylmethane-4,4-diisocyanate and 2.18 kg of butanediol-1,4. At the same time as the polymer-forming reactive components, 20 kg of dimethylformamide are charged into the reactor. The mixture is heated to a temperature of 60 ° C at which it reacts for about 4 hours. The course of the reaction is monitored by means of a flow-through viscometer. Under 50 viscosity, the solution is diluted with dimethylformamide to a final concentration of 30%. Once the necessary viscosity of 20 Pas is reached, the reaction is stopped with 0.5 kg of an ethyl alcohol terminator.

(b) The solution is prepared as described in (a), but a reaction mixture of 10 kg of polybutylene adipate of molecular weight 2000 (OH No.56), 6.0 kg of diphenylmethane-4,4-diisocyanate and 1.65 kg of butanediol is used. -1.4. The viscosity of the 30% solution is 20 to 21 Pas.

c) To prepare a solution as described in a), a reaction mixture of 10 g of polybutyl vinyl acetate 8 of molecular weight 2000, 10 kg of diphenyl ethane-4,4-diisocyanate and 3.05 kg of butanediol-1,4 was used. The reaction was terminated by the addition of 0.5 kg of ethanol to a 30% solution in dimethylformamide, to a viscosity of 20 Pas.

d) The polymer solution prepared as described in a) consists of 10 kg of polycaprolactan of molecular weight 2000, 8 kg of diphenylmethane-4,4-diisocyanate and 2.36 kg of butanediol -1.4.

(e) A solution prepared from 10 kg of polyhexamethylene adipate having a molecular weight of 1500, 7.5 kg of diphenylmethane-4,4-diisocyanate and 2.04 kg of butanediol-1,4 as described in a).

(f) A polyurethane solution prepared from 10 kg of 2000 molecular weight polyethylene butylene adipate (Desmophen 2001 or Systol 201), 7.5 kg of diphenylmethane-4,4-diisocyanate and 2.18 kg of butanediol-1,4 as described under a).

The viscosity of the solutions can be controlled over a wide range, however. for processing, solutions having a viscosity in the range of 12 to 50 Pas at 30% concentration are most suitable.

B / Preparation of the solution for the backing layer.

The backsheet solution is prepared by diluting the basic 30% solution with dimethylformamide to a concentration of 10%. Depending on the type of polymer, the aggressiveness of the solvent is adjusted by the addition of secondary solvents.

(a) The solution is prepared from 10 kg of the basic solution referred to in Aa) by adding 20 kg of dir methylformamide, 0.6 kg of non-ionic surfactant and 1 kg of water.

(b) A solution prepared from the polymer of (Ab), by mixing a mixture of 0.6 kg of a nonionic surfactant, 5 kg of ethyl alcohol, 0.2 kg of water and 20 kg of dimethylformamide into 10 kg of solution.

c) A solution prepared from 10 kg of the polymer mentioned in Ad) by admixing 20 kg of dimethylformamide, 4 kg of propanol-1, 0.2 kg of water and 0.7 kg of a nonionic surfactant.

d) A solution of increased water sorption prepared from 10 kg of polymer according to Aa) with 10 kg of a 30% hydrophilic polyurethane solution prepared from 1 mole of polybutylene adipate of molecular weight 2000, 0.4 mole of polyethylene oxide (polyethylene glycol), 4, 8 moles of diphenylmethane-4,4-diisocyanate and 3,4 moles of butanediol-1,4.

A water-swellable hydrophilic polyurethane which receives up to 200 to 300% by weight of polymer. 40 kg of dimethylformamide, 0.5 kg of water and 2 kg of nonionic surfactant are added to the solution.

Poromers prepared from this backing polymer are capable of absorbing 35-40% water to 2 mass solids, and have a water vapor permeability of 6-10 mg / cm hr.

Example 2

A. Manufacture of semi-finished upper products

The upper blanks are made of polyurethane solutions in dimethylformamide by first applying a solution of a linear polyurethane in an organic solvent to a hoof-shaped mold with a negative skin and sewing design. After the organic solvents are expelled in the air stream, a first poromeric layer is applied to this layer.

a) Dipping the first poromeric layer

In the first porous coating by dipping, the polyurethane solutions of Example 1 (Aa) to (Af) of Example 1 are treated as set forth in point B. In this manufacturing process, the solution is placed in a bath into which a hoof or mold enters. After emergence of the mold from the polymer solution bath, the layer of polymer adhered to the soil is first wiped off, then the mold is rotated to achieve a uniform spill of the polymer over the mold surface and hence an even porosity of the blank. The solution form goes into precipitation solutions, which are solutions of dimethylformamide in water containing 50 to 0% dimethylformamide. After the microporous layer has precipitated from the solution, the mold leaves for further processing.

b / Spraying the solution

When spraying the solution, the same solutions are used as in the dipping process, except that the viscosity is adjusted so that the solutions can be worked up on the equipment used. The viscosity is usually adjusted by dilution or heating.

The solutions shown in Example 1 (Aa) to (Af) and modified according to Example 1 (B) are diluted by adding 2 kg of dimethylformamide to 15 kg of solution so that their viscosity drops to 12-13 Pas. Heat to 40 ° C with a high-pressure spray gun to form a mold that is coated with a linear polaurethane.

The mold rotates during application to ensure a uniform thickness of the deposited solution over the entire surface of the mold. After application of a thickness of 0.7 to 1.2 mm, the mold is transferred to the precipitation bath as in Aa), the first microporous layer being precipitated,

B) Drying and stretching of reinforcing fabric.

After the first microporous layer has precipitated from the solution applied either by dipping or spraying, the coating surface is dried in an air stream and a seamed or knitted sock of knitted fabric is stretched onto the dried surface.

C) Applying the backing layer.

The backing layer is soaked on the mold that the first proportioning layer molded with the reinforcing fabric is immersed in a bath containing the backing polymer solution mentioned in Ca) to Cd) of Example 1. After the mold emerges from the solution, the excess solution is wiped off. Soil and mold will go to the collecting van.

D) Precipitation and washing.

The concentration of dimethylformymide in the precipitation bath is selected so that at least a 20% dimethylformamide solution is wasted with the washing of the precipitation line.

Concentrations in the first to fifth precipitation baths are successively 25 to 35%, 15 to 25%, 5 to 15%, 0 to 5%, 0% · The precipitation time in each bath is 5 minutes.

After shrinking, the blanks are removed from the mold and washed in a drum washing machine. The washed upper blanks are loaded onto stabilizing hooves and dried for 30 to 45 minutes at 135 to 155 ° C. During the drying process, the semi-finished product is dimensionally and dimensionally stabilized.

Claims (2)

SUBJECT OF THE INVENTION A method for producing a footwear, in particular an upper part thereof, by forming three-dimensionally from polymer solutions, in particular from polyurethane solutions in dimethylformamide, in which the uppers are formed by successively applying individual layers of polymer solutions to the hoof form. a layer of reinforced textile material is added to these layers, characterized in that a layer forming the outer surface of the shoe on the finished shoe is first applied to a hoof-shaped mold provided with a negative tread, and after application of the remaining layers . 2. A process according to claim 1, wherein polymers containing polyethylene glycol having a molecular weight of 600 to 6000 are added to the polymer solution forming the backing layer of the footwear.