KR102498036B1 - Eco-friendly artificial leather impregnated with water based polyurethanes and method for preparing thereof - Google Patents

Abstract

Unlike the conventional suede-like artificial leather manufactured by impregnating organic solvent-based polyurethane that requires an organic solvent, the present invention is impregnated with water-based polyurethane that does not use an organic solvent that has a harmful effect on the environment in manufacturing artificial leather. It relates to environmentally friendly artificial leather that enhances eco-friendliness and approaches the texture and durability of suede-like artificial leather using conventional organic solvents and a manufacturing method thereof. Specifically, the present invention is pre-dried in a cross-drying method in which only one side of a nonwoven fabric padded with an aqueous polyurethane solution is dried, and then dried with a tenter. Manufacturing of environmentally friendly artificial leather impregnated with water-based polyurethane It's about how.

Description

Eco-friendly artificial leather impregnated with water based polyurethanes and method for preparing the same

Unlike the conventional suede-like artificial leather manufactured by impregnating organic solvent-based polyurethane that requires an organic solvent, the present invention is impregnated with water-based polyurethane that does not use an organic solvent that has a harmful effect on the environment in manufacturing artificial leather. It relates to environmentally friendly artificial leather that enhances eco-friendliness and approaches the texture and durability of suede-like artificial leather using conventional organic solvents and a manufacturing method thereof.

Suede-like artificial leather is widely used as a high-quality material in many fields, such as interior materials, chair covers, interior and exterior materials for electronic products, shoe materials, automobile interior materials, and clothing materials, which are closely related to real life, with features such as luxurious appearance and comfortable feel. Conventional technology related to suede-like artificial leather made of conventional polyurethane that requires an organic solvent is already well known, and in recent years, it is manufactured using water-based polyurethane that does not use an organic solvent to meet the increasing eco-friendly demand. There is an increasing trend in the publicity of environmentally friendly manufacturing technologies.

Conventional organic solvent-based suede-like artificial leather is filled with two-component sea-island type microfiber nonwoven fabric with polyurethane dissolved in an organic solvent to remove one component of the two-component sea-island type microfiber and make it ultra-fine, followed by surface polishing, dyeing, functional post-processing, etc. It is manufactured through the process of Artificial leather using water-based polyurethane that does not require the use of an organic solvent can also be manufactured through a similar process by applying the conventional technical process of organic solvent-based artificial leather. However, when the two-component sea-island microfiber nonwoven fabric is filled with water-based polyurethane and dried with hot air, polyurethane is distributed only on both sides of the non-woven fabric due to the heat transfer characteristics of water-based polyurethane, and there is no impregnated resin inside the non-woven fabric. It is difficult to express the dense and flexible emotional quality and high durability that appear in artificial leather.

To solve this problem, water-based polyurethane with thermal coagulation properties is used for impregnation, and the impregnated non-woven fabric moving horizontally in the steamer is thermally coagulated with steam and microwaves to prevent the migration filling phenomenon and impregnation using conventional water-based polyurethane and vertically moving the nonwoven fabric and coagulating it with steam to prevent migration impregnation.

However, in the case of the above, the water-based polyurethane is slightly biased downward due to the effect of gravity as the water-based polyurethane moves horizontally until the nonwoven fabric impregnated with the water-based polyurethane is solidified by steam and microwave, so there is a limit to completely preventing migration. In the case described later, it is possible to prevent the bias of the padding solution to one side due to its own weight by vertically moving the nonwoven fabric padded with the water-based polyurethane in the initial steaming step, but the effect of the heat transfer of the water-based polyurethane Since it is not completely blocked, there is still a concern about migratory impregnation according to the work situation.

In addition, unlike organic solvent-based polyurethane, water-based polyurethane tends to be directly adhered to the surface of yarns in nonwoven fabric after impregnation and drying, thereby reducing the degree of freedom of the nonwoven fabric and reducing the flexibility. As a way to reduce this, before filling the two-component sea-island nonwoven fabric with water-based polyurethane, a water-soluble polymer such as PVA with a high degree of aeration and a silicone-based softener are first padded and treated, and then the water-based polyurethane is impregnated to form a direct contact with the fibers of polyurethane. In addition to preventing adhesion, a technique for enhancing flexibility by a softener has been devised.

However, improvement in flexibility can be expected by adding a silicone softener to the non-adhesive filling state of the water-based polyurethane resin with fibers, but the durability of artificial leather suede is lowered due to the non-adhesion between polyurethane resin and fibers and the characteristics of imparting lubrication. there is.

Korean Patent Publication 10-2020-0114340 (2020.10.07. Publication) Korean Patent Publication 10-2020-0036228 (2020.04.07. Publication) Korean Patent Publication No. 10-2020-0059215 (published on May 28, 2020)

In order to solve the above problems, the present invention is a method for manufacturing environmentally friendly suede-like artificial leather filled with water-based polyurethane that exhibits similar fillability, abrasion resistance and sensitivity to artificial leather made of conventional organic solvent-based polyurethane. It has one purpose to provide.

Another object of the present invention is to provide a suede-like artificial leather produced by the above-described manufacturing method, which exhibits excellent filling, abrasion resistance, and sensibility and is environmentally friendly.

As one aspect, the present invention provides a method for producing environmentally friendly artificial leather impregnated with water-based polyurethane.

As one specific aspect, the present invention is an environmentally friendly artificial product impregnated with water-based polyurethane, characterized in that the water-based polyurethane aqueous solution is pre-dried in a cross-drying method in which only one side of the padded nonwoven fabric is dried, and the main drying is performed with a tenta group. A method for producing leather is provided.

As a more specific aspect, the manufacturing method of environmentally friendly artificial leather impregnated with water-based polyurethane of the present invention,

(S10) a non-woven felt manufacturing step of preparing a non-woven felt from two-component sea-island microfibers and calendering them;

(S20) an impregnation drying step of impregnating the non-woven felt obtained in the non-woven felt manufacturing step in an aqueous polyurethane solution and drying;

(S30) a soluble component extraction step of preparing ultra-fine nonwoven fabric by extracting soluble components from the nonwoven fabric impregnated with the water-based polyurethane obtained in the impregnation and drying step;

(S40) a napping forming step of polishing the surface of the ultra-fine nonwoven fabric obtained in the soluble component extraction step to form napping.

Hereinafter, with reference to FIG. 1, a method for manufacturing an environmentally friendly suede-like artificial leather filled with water-based polyurethane according to the present invention will be described in detail.

(S10) non-woven fabric manufacturing step

The nonwoven fabric manufacturing step (step S10) is a step of manufacturing a nonwoven fabric felt from two-component sea-island microfibers and calendering it.

More specifically, the step (S10) is a step of preparing a non-woven felt from the two-component sea-island microfibers by needle punching or spun lacing, and heat-shrinking the manufactured non-woven felt to increase bonding density and calendering to impart surface smoothness. .

The two-component island-in-the-sea type microfiber is dissolved or decomposed in a solvent or alkaline environment with the first polymer of the first component (island component) remaining as microfiber after reduction in microfineness, and the second component (sea component) that is removed. ) Refers to microfibers produced by conjugate spinning of the second polymer.

The first polymer of the island component is a high molecular weight polymer that does not dissolve or decompose in a solvent or alkaline environment, and examples thereof include polyamide, polyvinyl alcohol, polyacryl, polyethylene terephthalate, and polymethylene terephthalate.

The second polymer of the sea component is a high-molecular polymer that dissolves or decomposes in a solvent or alkaline environment, and examples thereof include co-polyester, polyethylene, and polystyrene.

The non-woven felt refers to a non-woven fabric manufactured in a felt form by a conventional method using conjugate-spun two-component sea-island microfibers.

As a specific example, island-in-the-sea yarn in the form of short fibers cut to a fiber length of 38 mm to 64 mm is fed into a hopper feeder, carded, cross-wrapped, and then passed through a plurality of needle punching machines to produce a felted needle punched nonwoven fabric. there is.

In addition, the non-woven felt can be manufactured by applying any conventional bonding method for combining fibers into a felt form, such as needle punching or spun lacing using a needle punching machine or a spun lacing machine.

In addition, in order to secure the durability of artificial leather filled with water-based polyurethane, a reinforcing fabric (SCRIM) woven from plain weave of the same component as the island component is inserted into one side or an intermediate layer, and needle punching or spun lacing is performed. You may.

The prepared non-woven felt preferably has an apparent fiber density of 0.15 to 0.25 g/ccm, preferably 0.17 to 0.20 g/ccm. Such an apparent fiber density can ensure the durability of artificial leather filled with water-based polyurethane, which is finally prepared from the non-woven felt. If the apparent fiber density is less than 0.15 g/ccm, problems may occur in ensuring durability of artificial leather filled with the finally manufactured water-based polyurethane, and if the apparent fiber density exceeds 0.25 g/ccm, water-based polyurethane is finally manufactured. There is a concern that the touch of this filled artificial leather becomes very stiff.

The prepared non-woven felt is then passed through hot water to heat-shrink and dry to perform calendering in which it is processed into a uniform thickness.

When the water-based polyurethane is impregnated with the water-based polyurethane by the calendering, the water-based polyurethane is uniformly filled, and the density of the non-woven fabric is further increased and uniformed at the same time, so that a smooth and rich surface hair is formed during surface polishing.

(S20) Impregnation and drying step

The impregnation and drying step (step (S20)) is a step of impregnating the nonwoven fabric obtained in step (S10) with an aqueous polyurethane solution and drying it.

The water-based polyurethane aqueous solution is an aqueous solution containing 5 to 60% by weight of water-based polyurethane, and the water-based polyurethane may be appropriately contained according to a desired impregnation rate.

The aqueous polyurethane solution is water-soluble polyurethane, self-emulsifying polyurethane in which an anionic, cationic or nonionic hydrophilic group is introduced into the polyurethane resin backbone, and a forced-emulsifier type treated with a nonionic surfactant. ) It can be used by mixing a large amount of emulsifier with polyurethane or hydrophobic polyurethane resin and emulsifying and dispersing it by mechanical shear force.

The polyurethane is preferably polyurethane composed of components that do not dissolve or decompose in solvents or alkalis when soluble components are extracted from the two-component sea-island microfibers in the following step (S30). In particular, polyurethanes synthesized from polyether polyols, polycarbonate polyols, and polyester-polycarbonate polyols that exhibit hydrolysis resistance to alkalis are preferred.

The aqueous polyurethane solution may further include additives such as a pigment, a crosslinking agent, a dispersion stabilizer, an antifoaming agent, a thickener, and the like to improve the stabilization and mechanical properties of the aqueous polyurethane impregnation solution. Among these additives, it is preferable to use a thickener, for example, a urethane-based thickener, for the purpose of assisting in preventing migration of polyurethane dispersed particles due to evaporation of water when the aqueous polyurethane aqueous solution is dried after padding.

The aqueous polyurethane aqueous solution preferably exhibits a viscosity of 1,000 to 4,000cps, preferably 2,000 to 4,000cps at 25°C. When the viscosity is less than 1,000 cps (25 ℃), the aqueous polyurethane solution penetrates well when the nonwoven fabric is immersed in an aqueous polyurethane solution, but when dried, the polyurethane particles dispersed in water easily move in the same direction as the water as the water evaporates, making polyurethane It is easy to show the result of migration impregnation concentrated on both surfaces of the nonwoven fabric and less present in the inside, which leads to bad results in the quality of water-based artificial leather. When the viscosity is greater than 4,000 cps, there is a problem that the aqueous solution does not penetrate well when the nonwoven fabric is immersed in the aqueous polyurethane aqueous solution.

After impregnating the non-woven fabric with the aqueous polyurethane solution, a step of compressing and dehydrating the non-woven fabric so that the aqueous polyurethane solution is padded in a certain amount before drying may be further included.

The compression dehydration may be performed by a method well known in the art, such as a mang roller.

The nonwoven fabric padded with the aqueous polyurethane solution is dried, and the drying is divided into preliminary drying and main drying.

Conventionally, drying of the nonwoven fabric padded with aqueous polyurethane solution did not distinguish between pre-drying and main drying, or was mainly dried using hot air from a hot air blower. When using a drying facility using hot air, the water-based polyurethane padded non-woven fabric is simultaneously thermally contacted on both sides of the upper and lower sides, so that water evaporates simultaneously on both surfaces of the non-woven fabric. At this time, the water-based polyurethane particles dispersed in the water also As a result, there is no resin inside the nonwoven fabric, and resin particles are concentrated on both surfaces and dried, resulting in migration impregnation. In addition, the conventional drying method has a practical problem that is not easy to utilize in actual industrial sites due to high equipment investment costs and difficulties in process management.

Unlike this, the drying of the present invention is divided into preliminary drying and main drying, and the preliminary drying is a cross-drying method in which only one side of the nonwoven fabric is dried and then the other side is dried, rather than simultaneously drying both sides of the nonwoven fabric.

As one specific example, as can be seen in FIG. 2, in the preliminary drying of the present invention, primary drying is performed by applying a heat source only to one side of the nonwoven fabric, and secondary drying is performed by applying a heat source only to the other side of the nonwoven fabric, and the first Thirdly drying by applying a heat source only to one side of the secondly dried nonwoven fabric, fourth drying by applying a heat source only to the other side of the secondarily dried nonwoven fabric, and fifth drying by applying a heat source only to one side of the thirdly dried nonwoven fabric. cross-drying methods such as

When cross-drying in which one side of the nonwoven fabric is firstly dried and then the other side of the nonwoven fabric is secondarily dried is referred to as one-time drying, the cross-drying is performed one or more times, preferably 1 to 4 times, more preferably 2 to 4 times. times, more preferably 2 to 3 times, and most preferably 2.5 times.

In addition, the time for applying a heat source to any one side of the nonwoven fabric to dry any one side of the nonwoven fabric is 1 second or more, preferably 1 to 8 seconds, more preferably 1 to 6 seconds, even more preferably 1 to 5 seconds can

However, the drying number and drying time may be appropriately adjusted according to the weight or area of the nonwoven fabric to be dried, the content of the padded water-based polyurethane, the temperature and energy of the heat source, and the production speed. In addition, the number of times of drying and the drying time may be appropriately adjusted depending on whether a heat source supplier for providing a heat source to only one side of the nonwoven fabric is in operation.

A heat source supplied to only one side of the nonwoven fabric is not necessarily limited thereto, but includes infrared rays, microwaves, hot air, and the like. In particular, when using hot air, it is natural for the purpose of the present invention that hot air should be provided to only one side.

The nonwoven fabric padded with the aqueous polyurethane solution by the pre-drying has a moisture content of 50% or less, preferably 40% or less, more preferably 15 to 30%, and still more preferably 20 to 25%. By drying, the moisture content is 10% or less, preferably 8% or less, more preferably 5 to 8%.

In the main drying, the pre-dried nonwoven fabric may be dried using a conventional dryer, for example, a tenter. The drying temperature and time of the main drying may vary depending on the moisture content according to pre-drying and the desired final moisture content. As an example, it was performed at 150 ° C. for 10 seconds.

As one specific example, the pre-drying used 5 sets of infrared heaters arranged vertically in a zigzag form, and the main drying used a tenter (see FIG. 2).

(S30) Soluble component extraction step

The step of extracting the soluble component ((S30) is a step of extracting the soluble component from the nonwoven fabric impregnated with the water-based polyurethane obtained in the step (S20) to manufacture an ultra-fine nonwoven fabric.

The extraction of the soluble component means the removal of the second polymer, which is the sea component, and may be performed using a solvent or an alkaline aqueous solution capable of dissolving or decomposing the second polymer.

As one specific example, the water-based polyurethane-impregnated nonwoven fabric was immersed in a 2% (w/w%) aqueous caustic soda solution at 95° C. for 15 minutes to remove sea components and to prepare an ultra-fine nonwoven fabric.

After extraction of the soluble component, it is washed with water and dried in a conventional manner.

(S40) Raising step

The step (S40) is a step of forming naps by polishing the surface of the ultra-fine nonwoven fabric obtained in the step (S30).

Grinding and napping of the ultra-fine nonwoven fabric may be performed by a conventional method, for example, polishing may be performed using sandpaper or the like.

After the step (S40), if necessary, it may be dyed with a dye solution and dried. Such dyeing and drying may be performed by conventional methods.

In addition, after the step (S40) or dyeing, for the purpose of improving texture and flexibility, a general physical and chemical softening process and, if necessary, special processing such as water repellency, antibacterial and antifouling can be performed to achieve a variety of uses.

In the artificial leather manufactured by the above method, the water-based polyurethane is not concentrated on both surfaces of the nonwoven fabric and is evenly distributed inside (see FIGS. 3 and 4), so that the artificial leather impregnated with water-based polyurethane according to the conventional method has a stiff texture , it does not exhibit insufficient flexibility or low durability, but exhibits texture, flexibility, and durability equivalent to artificial leather impregnated with organic solvent-based polyurethane.

Therefore, as another aspect, the present invention provides artificial leather having texture, flexibility and durability equivalent to artificial leather impregnated with organic solvent-based polyurethane prepared by the above method.

The above-described artificial leather is a material that replaces natural leather and can be usefully used for interior materials, chair cover materials, interior and exterior materials for electronic products, shoemaking materials, automobile interior materials, and clothing materials.

When water-based polyurethane suede-like artificial leather is manufactured according to the present invention, water-based polyurethane is uniformly distributed inside the nonwoven fabric so as not to be biased to both surfaces and filled in a network form (preventing migration impregnation), so that conventional organic solvent-based polyurethane It is possible to manufacture artificial leather in a filled state equivalent to this impregnated artificial leather. Due to the filling state without polyurethane leaning to both surfaces, it is possible to compensate for the disadvantages of conventional water-based artificial leather such as stiff texture, insufficient flexibility, and low durability, improving the texture and durability of suede artificial leather using conventional organic solvents. It is possible to manufacture an environmentally friendly suede-like artificial leather.

1 is a diagram showing a manufacturing method of water-based polyurethane-impregnated artificial leather according to an embodiment of the present invention.
2 is a schematic diagram showing a drying process of a nonwoven fabric impregnated with water-based polyurethane in step (S20) according to an embodiment of the present invention.
Figure 3 is a schematic diagram showing the state (b) of the impregnated section (a) in which migration impregnation has occurred by a conventional water-based polyurethane impregnation and drying method and the impregnation section (b) in which migration has not occurred according to the present invention to prevent migration impregnation.
4 is an optical microscope photograph of a cross-section of a water-based polyurethane-impregnated nonwoven fabric manufactured according to Example 1 and Comparative Example 2 according to an embodiment of the present invention.

Hereinafter, examples and the like will be described in detail to aid understanding of the present invention. However, the embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the following examples. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example 1:

In the two-component sea-island type microfiber, polyethylene terephthalate was used as the island component and co-polyester was used as the sea component. After releasing the carded web fleece formed in multiple layers by blending, carding, carding, and cross-lapping, a 30 g/sm polyester plain fabric is placed on the underside of the web fleece as a reinforcing fabric, passed through a number of needle punching machines, and needle punched to make felt. A needle-punched nonwoven fabric having a thickness of 360 g/sm and a thickness of 1.95 mm was prepared.

The needle punched nonwoven fabric prepared above is immersed in 80 ° C hot water to shrink, passed through a mangler to squeeze out excess water, passed through a dryer heated to 150 ° C to dry, and passed between two calender rollers heated to 150 ° C The surface was processed to be smooth.

After immersing and squeezing the prepared nonwoven fabric in an aqueous polyurethane impregnating solution adjusted to a viscosity of 1,500cps (25 ℃) by adding a thickener to an aqueous polyurethane aqueous solution containing 30% of aqueous polyurethane solid content, and then squeezing, an infrared heater was installed. The water-based polyurethane was solidified by passing through a pre-dryer and completely dried at 150 ° C. using a tenter dryer to prepare a nonwoven fabric impregnated with water-based polyurethane.

The water-based polyurethane-impregnated nonwoven fabric is immersed in a caustic soda solution with a concentration of 2% (w/w%) and treated at 95° C. for 15 minutes to make the island-in-the-sea yarn of the impregnated nonwoven fabric ultra-fine, washed with water, and dried to ultra-fine non-woven fabric. processed with

Thereafter, the surface of the ultra-fine nonwoven fabric was polished to form naps, then dyed with a disperse dye using a liquid dyeing machine and washed by reduction to obtain suede-like artificial leather.

Example 2:

In Example 1, the procedure was performed in the same manner as in Example 1 except that an impregnation solution having a viscosity of 3,000cps (25° C.) of the aqueous polyurethane impregnation solution was used.

Comparative Example 1:

In Example 1, the same procedure as in Example 1 was performed except that an impregnation solution having a viscosity of 500cps (25° C.) of the aqueous polyurethane impregnation solution was used.

Comparative Example 2:

In Example 2, the same procedure as in Example 2 was performed except that the pre-drying using an infrared heater was not performed and only the tenta was dried.

Conditions and characteristic evaluation results of the artificial leather prepared through the above examples and comparative examples are summarized in Table 1 below.

degree of impregnation
(cps/25℃) drying method migration impregnation filling texture surface brushing durability Example 1 1,500 infrared + tenta Non-occurrence (good) ○ excellent/uniform Pass Example 2 3,000 infrared + tenta Non-occurrence (good) ◎ excellent/uniform Pass Comparative Example 1 500 infrared + tenta occurrence (bad) △ Coarse/uneven Fail Comparative Example 2 3,000 Tenta occurrence (bad) × Coarse/uneven Fail * Evaluating whether or not migration impregnation occurs: Optical microscope
* Filling texture and surface brushing evaluation method: sensory evaluation by 5 people
* Durability evaluation method: ISO 12947-2-2016(E), Martindal Method, 9kPa
(End Point : One thread completely broken)
Under 300,000cycles -> Fail
Over 300,000cycles -> Pass

From Table 1, it can be seen that the examples according to the present invention show superiority in evaluation quality than the comparative examples.

In addition, the suede-like artificial leather manufactured according to the present invention can sufficiently replace the use of organic solvent-based artificial leather due to its sensitivity and durability characteristics comparable to conventional organic solvent-based artificial leather and can further meet the eco-friendly needs. It can be applied to high-quality materials that are available.

Claims (9)

A heat source of infrared rays, microwaves or hot air is applied to only one side of a two-component sea-island type microfiber composite radial nonwoven fabric impregnated with an aqueous polyurethane solution having a viscosity of 1,000 to 4,000 cps at 25 ° C. After drying only one side, infrared rays are applied only to the other side , A method for producing environmentally friendly artificial leather impregnated with water-based polyurethane, characterized in that pre-drying is performed in a cross-drying method in which only the other side is dried by applying a heat source of microwave or hot air, followed by main drying with a tenter. delete The water-based poly according to claim 1, wherein the pre-drying of the cross-drying method is 1 to 4 times when cross-drying in which one side of the nonwoven fabric is first dried and then the other side of the nonwoven fabric is secondarily dried is referred to as one-time drying. Manufacturing method of environmentally friendly artificial leather impregnated with urethane. (S10) a non-woven felt manufacturing step of preparing a non-woven felt from two-component sea-island microfibers and calendering them;
(S20) The non-woven felt obtained in the non-woven felt manufacturing step is impregnated with an aqueous polyurethane solution having a viscosity of 1,000 to 4,000 cps at 25 ° C, and then only one side is dried by applying a heat source of infrared rays, microwaves or hot air to only one side. Afterwards, an impregnation drying step of pre-drying in a cross-drying method in which only the other side is dried by providing a heat source of infrared rays, microwaves, or hot air, and finally drying with a tenta machine;
(S30) a soluble component extraction step of extracting soluble components from the nonwoven fabric impregnated with the water-based polyurethane obtained in the impregnation and drying step to produce ultra-fine nonwoven fabric;
(S40) A method for producing environmentally friendly artificial leather impregnated with water-based polyurethane, comprising a napping forming step of polishing the surface of the ultra-fine nonwoven fabric obtained in the soluble component extraction step to form napping. delete delete The method of claim 4, wherein the cross-drying is impregnated with water-based polyurethane, characterized in that 1 to 4 times when the cross-drying of first drying one side of the nonwoven fabric and then secondarily drying the other side of the nonwoven fabric is referred to as one drying. Manufacturing method of environmentally friendly artificial leather. delete delete

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