KR100314399B1 - Manufacture of artificial leather using waterborne polyurethane as polymer matrix - Google Patents

Abstract

The present invention relates to a method of manufacturing artificial leather using a water-dispersed polyurethane, and to provide a method of manufacturing artificial leather to be processed after being supported with a water-dispersed polyurethane in a microfiber nonwoven fabric.

That is, the present invention, in the production of microporous artificial leather using a water-dispersed polyurethane, a process using a compound that decomposes an inorganic salt by heat to generate an acid or a compound that decomposes an inorganic salt by heat to generate carbon dioxide The process or the process using the compound which produces | generates an acid by decomposing an inorganic salt by heat, and the process using the compound which produces | generates carbon dioxide by decomposing an inorganic salt by heat is mixed.

Description

Manufacture method of artificial leather using waterborne polyurethane as polymer matrix

The present invention relates to a method of manufacturing artificial leather using a water-dispersed polyurethane, and more particularly to a method of manufacturing artificial leather to be processed after being supported with a water-dispersed polyurethane in a microfiber nonwoven fabric.

As a substrate for making resin impregnated fabrics, woven fabrics, general nonwoven fabrics, and microfiber nonwoven fabrics made of microfiber are commercially used, and resin impregnated fabrics using such substrates are artificial leathers, hard sheets, and diapers that mimic natural leather. It can be usefully used according to various purposes such as, it is widely generalized and commercially available.

Techniques such as a method of coating a substrate by impregnating a polymer material such as polyurethane on a substrate such as a woven fabric and a nonwoven fabric having a porosity and then drying it to commercialize the impregnated fabric itself or coating a polymer using a polymer similar to the impregnated polymer on the impregnated fabric.

Polyurethane (PU) can easily control chemical stability and mechanical property change due to its material characteristics, and has a wide range of application as a filling material for composites requiring hard or soft, and there are various technologies for supporting polymer resin on porous substrates. It is widely known.

In the impregnation technique using an organic solvent type polymer resin, a wet method using water as a coagulation medium of the resin is well known.

The wet process consists of a continuous process of an impregnation tank, a coagulation tank, a water washing tank, and a drying furnace.

After impregnating the solution into the porous substrate in an impregnation tank filled with a solution of 3-15% resin and a viscosity of 80-1500 cps, the solution was left in a coagulation bath mixed with a solvent / water ratio of about 10/90 for about 50 minutes. Solidification of the resin occurs due to the incompatibility of the resin with the resin.

In the coagulation bath, water diffuses into the impregnating cloth, and the solvent in the impregnating cloth diffuses into the coagulation cloth, and a considerable amount of solvent in the impregnating cloth is removed. In this process, the resin itself contained in the impregnating cloth is porous due to the phase separation of water and resin. The pores are formed and the remaining solvent is completely removed by washing with water, and the pores make the product elastic and soft.

In the case of using such solvent-type polymer resins, most solvents are very toxic and a recovery process must be followed for reuse or disposal.

In addition, these solvents are being questioned in the recently strengthened environmental regulations, and various mixed solvents have been developed that are less toxic to the human body and do not deviate significantly from air pollution standards, but the price is quite expensive and still infringes on the human body or the environment.

In order to alleviate this problem of solvent-type polymer resins, a lot of water-dispersion polymer polymerization methods have been developed.

Impregnation method using a water-dispersible polymer resin is a technique that has been previously known to dilute excess water in a 30% solid-state aqueous polymer solution to produce an impregnation solution of 4% or less solid content, it is supported on a high-density nonwoven fabric or a microfiber nonwoven fabric immediately There is a dry method of drying.

This dry method has a low solids concentration, which results in the loss of resin properties and the increase of non-woven fabrics, resulting in low value as a product, and the movement of the resin toward both surfaces of the impregnated cloth during evaporation of water during drying. It is classified as a low grade product because it cannot make a needle.

In order to solve the problem of the water-dispersed polymer, a physical processing method using wet heat and ultrasonic waves has been attempted, but the mechanical installation cost and operation cost are very expensive compared to the quality of the product.

Accordingly, in the present invention, first, a commercially available environment-friendly type of water-dispersed polyurethane is polymerized to select a water-dispersed polyurethane having elongation, elastic modulus and chemical stability suitable for physical and chemical properties of artificial leather.

In addition, various inorganic salts were used to form the porous 30% resin stock solution on the microfiber nonwoven fabric to form porous pores that can impart fullness and softness when the resin solidified. The study was conducted.

As a result, the present invention was able to find the optimum conditions in several inorganic salts, and the present invention was repeated to complete the present invention.

The water-dispersed polyurethane production method used in the present invention used a well-known prepolymer mixing process.

The prepolymer mixing process is a method of dispersing a low molecular weight prepolymer having low viscosity and ionic groups in water and then using a chain extender to make a polymer dispersion. There is an advantage to use less.

First, a polyol and a catalyst were added thereto, and the stirring speed was sufficiently stirred at 95 ° C. at a rate of about 100 revolutions per minute, and then the isocyanate was reacted until the theoretical value of the isocyanate group was reached.

Dimethylolpropionic acid (DMPA) and alcohols (alcohols) were added, and then reacted to theoretical values, respectively, and a small amount of acetone was added for viscosity control.

After cooling to 60 ° C., a neutralizing agent was added and reacted for about 1 hour.

Subsequently, the mixture was water-dispersed at a stirring speed of about 1500 revolutions per minute at room temperature, and then a chain extender of amines dissolved in water was added thereto and reacted for about 2 hours.

The ratio of isocyanate: polyol in the raw material was 5% by weight in consideration of the reaction with water in the synthesis process and the side reaction with water in the water dispersion process.

At this time, the carboxylic acid weight fraction used as an ionic center to stabilize the dispersion was adjusted to approximately 0.9 to 1.0% based on the total polymer weight.

Finally, the acetone remaining in the dispersion was removed by a rotary vacuum evaporator.

These water-dispersed polyurethanes are easy to disperse and have high storage stability because of the presence of ionic groups in the prepolymer. (For reference, suitable raw materials were selected from various literatures.)

Isocyanates and polyols, which are the main raw materials of polyurethane, are widely used commercially,

Isocyanates include cyclohexyl-1,4-diisocyanate (H12MDI) and isophorone diisocyanate (IPDI), which are cycloalipatic, stable to water, and relatively low in yellowing and toxicity.

The polyol used polytetramethylene ether glycol (PTMG) and polypropylene ether glycol (PPG) which are excellent in adhesive force and high in elasticity.

In the case of chain extenders, butanediol (BD) and hexamethylenediol (HD) can be enhanced as diols, and aminediamine (EDA) and diethylenetriamine are used depending on the number of functional groups. (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) were used.

As a raw material which is considered to be suitable for the manufacture of artificial leather of the present invention, the molar ratio of cyclohexyl-1,4-diisocyanate (H12MDI) / isophorone diisocyanate (IPDI) was about 3-7, and the polyol was methylene ether glycol ( PTMG) / polypropylene ether glycol (PPG) has a molar ratio of 2 to 8 and butanediol (BD) was used to impart mechanical properties.

Ethylenediamine (EDA) having 2 functional groups was used as the chain extender, and dimethylolpropionic acid (DMPA) having carboxylic acid was used as the internal emulsifier.

The polyurethane used in the present invention has a thermoplastic property that does not crosslink unless an external crosslinking agent is added.

Since the viscosity is adjustable according to the characteristics of the carrier, the viscosity range was set to 10 to 1000 c.p.s, and the water concentration was dispersed at about 10 to 40%.

No emulsifier was used for the stability of the dispersion.

As the supporting substrate used in the present invention, a woven fabric, a general nonwoven fabric, a microfiber nonwoven fabric, or the like was used.

In the process of the present invention, about 30% polyurethane was first supported on the substrate.

Since the substrate is porous, the water-dispersed polyurethane is loaded into the pores of the substrate by viscosity control, and a hydrophilic substrate is used to make the speed faster.

Therefore, the high porosity of the impregnated cloth will greatly affect the properties of the composite.

As inorganic salts capable of forming porosity, sodium silicate (Na ₂ SiF ₆ ), potassium silicate (K ₂ SiF ₆ ), sodium hydrogen carbonate (NaHCO ₃ ), water glass, etc., which were stable at room temperature, were used. A single component or a mixed component was used so that the weight composition ratio of the inorganic salt in the impregnation liquid was in the range of 0.001 to 10%.

The component of the urethane impregnation liquid used in this invention consists of the preparation which consists of water dispersion polyurethane of 30% of solid content, and an inorganic salt, and ionic water.

In order to prevent the ionization of the inorganic salt, the weight composition ratio of ethyl alcohol in the impregnation solution was changed to a range of 3 to 70% to confirm stability.

The impregnated nonwoven fabric is heated in a drying furnace, and sodium silicate (Na ₂ SiF ₆ ) or potassium silicate (K ₂ SiF ₆ ) is decomposed to produce an acid, which causes the resin to become unstable and gelation occurs.

A small amount of sodium bicarbonate (NaHCO ₃ ), composed of many components of the preparation, generates carbon dioxide by heat, and the amount of acid by decomposition of sodium silicate (Na ₂ SiF ₆ ) or potassium silicate (K ₂ SiF ₆ ) is excessive. Reacts with (NaHCO ₃ ) to neutralize excess carbon dioxide and stable salts.

The carbon dioxide generated in the resin solidified in this process forms many pores.

Inorganic salt preparation was pulverized for 4 hours in a ball mill (ball mill) was used for more than 300 mesh (mesh).

The ingredients of the preparation were divided into four categories: first sodium silicate (Na ₂ SiF ₆ ), sodium bicarbonate (NaHCO ₃ ), water glass, ethyl alcohol, second potassium silicate (K ₂ SiF ₆ ), Sodium bicarbonate (NaHCO ₃ ), water glass, ethyl alcohol Third sodium bicarbonate (NaHCO ₃ ), water glass, ethyl alcohol, fourth sodium silicate (Na ₂ SiF ₆ ), potassium silicate (K ₂ SiF ₆ ), sodium hydrogen carbonate (NaHCO ₃ ), water glass, ethyl alcohol and the like were combined in an appropriate composition to obtain optimum conditions.

Stability experiments were considered stable if the ratio of impregnation solution / preparation was mixed to 100/2 and no gelation occurred within a week.

This is reasonable because in practice the impregnation solution is consumed within two days after formulation.

The smaller the amount of alcohol was, the more unstable. When the weight composition of the impregnation liquid was more than 30%, all four classes showed satisfactory stability.

Scanning electron microscopy (SEM) analysis revealed that pore formation was the first with the highest porosity of sodium silicate (Na ₂ SiF ₆ ), sodium hydrogen carbonate (NaHCO ₃ ), and water glass.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, of course, the present invention is not limited to the following examples.

EXAMPLE 1

In order to prepare an inorganic salt preparation into about 0.001% to 10% of the impregnation solution provided by the present invention, 20 g of sodium silicate (Na ₂ SiF ₆ ), 30 g of sodium bicarbonate (NaHCO ₃ ), and 50 g of ethyl alcohol were prepared in 300 mesh. Grinding (mesh) to prepare the inorganic salt preparation into the dough state.

0.2 g of water glass was dissolved in 100 g of water-dispersed polyurethane, followed by dissolving 2 g of the inorganic salt preparation described above. This impregnation solution showed stability over 15 days.

The microfiber nonwoven fabric was cut into 30 cm and 50 cm lengths, impregnated with the impregnation solution, and passed through a roller to dry completely for 10 minutes in a dryer at 100 ° C.

At this time, the dried impregnated fabric has elasticity and softness, and was able to manufacture artificial leather like real leather in the microfiber dissolution process.

EXAMPLE 2

The impregnating liquid of the same composition as in Example 1 was cut into 30 cm wide and 50 cm long impregnated into the impregnation liquid, and then passed through a steam roller (mangle) and left in water at 40 ° C. for 20 minutes.

Squeezed the water absorbed into the impregnated cloth again with a roller and dried for 10 minutes.

Gel passage of the water-dispersed resin occurs to some extent during the passage of the steam roller did not occur diffusion of the water-dispersed resin in the water, it was possible to produce a softer microporous impregnated fabric than the immediately impregnated fabric.

As described in detail above, the present invention polymerizes various types of environmentally friendly water-dispersed polyurethanes to select water-dispersed polyurethanes having elongation, elastic modulus, and chemical stability suitable for physical and chemical properties of artificial leather. By using various inorganic salts to form porous pores that can impart softness, various benefits, such as being environmentally friendly, harmless to the human body, and inexpensive production of high-quality products, can be produced by solving the instability of the impregnation liquid by inorganic salts. This is given invention.

Claims (7)

(Twice correction) In the process of producing a microporous artificial leather using a water-dispersed polyurethane; When impregnating the substrate for manufacturing artificial leather into the impregnation solution, the impregnation solution contains about 0.001 to 10% of sodium fluoride (Na ₂ SiF ₆ ) or potassium fluoride as the weight ratio of the impregnation solution with the inorganic salt. (K ₂ SiF ₆ ), Method for producing artificial leather using a water-dispersed polyurethane, characterized in that the impregnating solution to which the ethyl alcohol of about 3 to 70% is added as a weight composition ratio to the impregnating liquid to impart stability to the impregnation solution. (Twice correction) The method of claim 1; The inorganic salt is a method for producing artificial leather using a water-dispersed polyurethane, characterized in that about 0.001 to 10% sodium hydrogen carbonate (NaHCO ₃ ) as a weight composition ratio for the impregnation solution. (Twice correction) The method of claim 1; The inorganic salt is about 0.001 to 10% sodium silicate (Na ₂ SiF ₆ ), or potassium silicate (K ₂ SiF ₆ ), and sodium hydrogen carbonate (NaHCO ₃ ) at the same time as a weight composition ratio to the impregnation solution. Method for producing artificial leather using a water-dispersible polyurethane, characterized in that. (Twice correction) The method of claim 1; As a stabilizer for imparting stability to the impregnating solution, at least one of a basic compound, methyl alcohol, or acetone, and an alcohol group or a compound having a ketone group may be alternatively added at about 3 to 70% by weight of the impregnating solution. Method of manufacturing artificial leather using a water-dispersed polyurethane, characterized in that. (delete) (delete) (delete)