WO2021025211A1 - Artificial leather comprising circular knitted fabric backside layer and method for manufacturing same - Google Patents

Abstract

The present invention relates to artificial leather used for a vehicle seat cover and, more particularly, to artificial leather comprising a circular knitted fabric backside layer and a method for manufacturing same, the artificial leather comprising from the bottom up: a backside layer; a foam layer; and a skin layer, the backside layer being a circular knitted fabric formed by means of a combined yarn having a predetermined thickness. The artificial leather is inexpensive, does not have see-through holes even after punching and exhibits excellent mechanical properties such as tensile strength.

Description

Artificial leather comprising the back layer of circular knitted fabric and its manufacturing method

The present invention relates to an artificial leather used as a car seat cover, specifically, the back layer from the bottom to the top; Foam layer; And a skin layer; In artificial leather including, the back layer is a circular knitted fabric formed by using a ply yarn having a specific thickness.It is a circular knitted fabric that is inexpensive, does not have a hole penetration phenomenon even after punching, and has excellent mechanical properties such as tensile strength. It relates to an artificial leather comprising a back layer and a manufacturing method thereof.

The interior of a vehicle is recognized as a second residential space, and recently, a functional sheet having excellent ventilation is required for comfortable and comfortable driving in such an interior space of a vehicle, and thus, punching products of the main part of the vehicle seat are in the spotlight.

Meanwhile, as a material for automobile seats, artificial leather made of inexpensive polyvinylchloride (PVC) or thermoplastic polyurethane (TPU) is in the spotlight.

In general, the artificial leather is made of a laminated structure including a back layer, a foam layer, and a skin layer from below. As an example for implementing a punching-type artificial leather, the back layer is a ring using conventional single yarn. When manufacturing with a knitted fabric, when punching artificial leather, there was a quality problem in which the yarn was released from the hole in the perforated part, so that the yarn cut in front and behind the punching hole was reflected, or mechanical properties such as tensile strength were deteriorated (see Fig. 1). .

In order to solve the above problem, as disclosed in Korean Patent Application Publication No. 10-2017-0030244 (published date: March 17, 2017), the back layer was manufactured with a warp knitted fabric or a nonwoven fabric, and then used as a polyurethane blending solution. Even after punching by impregnation, it was attempted to prevent hole penetration and secure mechanical properties such as tensile strength, but the warp knitted fabric and nonwoven fabric had a disadvantage that could be applied only to high-end vehicles because the warp knitted fabric and nonwoven fabric were too expensive.

Accordingly, there is an urgent need to develop artificial leather including the back layer, which is a circular knitted fabric with excellent mechanical properties such as tensile strength, which is inexpensive and does not have a hole-through phenomenon even after punching.

〔Prior technical literature〕

[Patent Literature]

(Patent Document 1) KR No. 10-2017-0030244 (Publication date: March 17, 2017)

In order to solve the problems of the prior art as described above, the present invention provides an artificial leather including a back layer, which is a circular knitted fabric having excellent mechanical properties such as tensile strength, and a method for manufacturing the same, which is inexpensive and has no hole penetration phenomenon even after punching. It is aimed at.

In order to achieve the above object, the present invention provides an artificial leather comprising a back layer which is a circular knitted fabric using a number of 5-30 ply.

In addition, the present invention provides a method for manufacturing artificial leather comprising the step of forming a back layer, which is a circular knitted fabric using a number of 5-30 ply.

The artificial leather of the present invention includes a back layer, which is a circular knitted fabric using 5 to 30 ply yarns, so that the price is low, there is no hole seepage even after punching, and mechanical properties such as tensile strength are excellent.

1 is a photograph showing a hole in a perforated portion after punching an artificial leather including a back layer, which is a circular knitted fabric using a conventional single yarn.

Figure 2 is a photograph showing a hole in the perforated portion after punching the artificial leather including the back layer of the circular knitted fabric of the present invention.

3 is a view showing an example of single yarn (a) and ply yarn (b) of the present invention.

Figure 4a is a view showing a specimen for measuring tensile strength and elongation.

Figure 4b shows the mark (ℓ ₁ , ℓ ₂ ) drawn on the specimen for measuring the static load elongation and residual shrinkage.

Figure 4c is a view showing a specimen for measuring the tear strength.

4D is a schematic view showing a part of a tensile testing machine.

Fabrics are largely divided into non-woven fabrics, woven fabrics, and circular knits depending on the manufacturing method.

The nonwoven fabric refers to a fabric shape in which fibers are bonded to each other by chemical or mechanical action or suitable moisture and heat treatment.

The woven fabric refers to a fabric formed through a woven process using the yarn after forming the fiber aggregate with yarn.

The woven fabric is a word commonly used with a fabric, and the woven fabric refers to a fabric in which two yarns are entangled in a horizontal and vertical direction, and refers to a fabric in which two yarns are entangled in a horizontal and vertical direction, that is, a yarn in a vertical direction, that is, a yarn in a horizontal direction . The woven fabric can be divided into plain weave, twill weave, and juja weave according to the manufacturing method, and the woven fabric has a disadvantage of deteriorating workability when used for automobile interior parts due to its strong structure but not elasticity.

The knitted fabric refers to a fabric woven by successively woven with one or two or more yarns, and may be divided into circular knitted fabrics and warp knitted fabrics according to a manufacturing method, Compared to woven fabric, it has the advantage of good elasticity. The circular knitted fabric means a fabric woven by yarns being woven in the direction of the weft, and the warp knitted fabric means a fabric woven by yarn being woven in a warp direction.

The present invention relates to an artificial leather comprising a back layer, which is a circular knitted fabric using a number of 5-30 ply.

In the present invention, the happier (合絲, b) means a yarn that is twisted while combining two or more single yarns (單絲, a) (see Fig. 3(b)).

The single yarn (a) is a single yarn made by twisting fibers, which is the simplest and means a yarn that can be woven by itself (see Fig. 3(a)).

Specifically, the single yarn (a) may be classified into a filament yarn and a spun yarn according to the length of the fiber.

The filament yarn is a yarn made of fibers having an infinite length, natural fibers such as silk fibers, regenerated fibers such as rayon fibers or cupra fibers, and polyester fibers, polyolefin fibers, polyvinyl alcohol fibers, polyamide fibers, It may be a single yarn made of one type of fiber selected from the group consisting of polyurethane fibers or synthetic fibers such as polyvinylidene chloride fibers.

The spun yarn is a yarn made of fibers (short fibers) having a short length of about 0.5-2.5 inches, and natural fibers such as cotton fibers, hemp fibers, wool fibers or wool fibers excluding silk fibers, and the filament yarn are spun It may be a single yarn in which one or two or more fibers selected from the group consisting of short cut fibers to the appropriate length below are mixed.

As a specific embodiment of the single yarn (a) in the present invention, it is possible to easily secure mechanical properties and flame-retardant properties, and polyester fibers and cotton fibers having the advantage of implementing sewing performance and clean appearance are 60-70 : Single yarn blended at a weight ratio of 30-40 may be used, and more specifically, melange yarn in which the at least one fiber is dyed for color implementation may be used.

The number of twists of the single yarn (a) may be 450-600tpm (turns per meter, twist number/1m) or 500-580tpm. The number of twists of the single yarn (a) can be measured by using a tester using a twisted twisting method according to KS K 0417.

If it is less than the above range, the strength decreases and the yarn is released from the hole portion of the perforated portion when punching artificial leather, so that the yarn cut in front of and behind the punching hole is reflected (i.e., hole seepage phenomenon), or mechanical properties such as tensile strength may decrease. If the range is exceeded, the cost may increase, which may be undesirable, and thus the number of twists within the range may be obtained.

In addition, the single yarn (a) may be 20-40 times or 20-30 times. If it is less than the above range, the strength decreases as the spatial density between the yarn and the yarn decreases, and when punching artificial leather, the yarn is released from the hole in the perforated part, causing the yarn cut in front and behind the punching hole to appear, or mechanical properties such as tensile strength may decrease. In addition, if it exceeds the above range, the strength decreases, and when punching artificial leather, the yarn is released from the hole in the perforated part, and the yarn cut in front and behind the punching hole may be reflected, or mechanical properties such as tensile strength may decrease. I can.

The braided yarn (b) of the present invention is a yarn twisted by combining 2-4 or 2-3 single yarns (a). When the number of single yarns (a) is less than the above range, the number of twists is small During punching, the yarn is released from the hole portion of the perforated portion, so that the yarn cut in front and behind the punching hole may be reflected, or mechanical properties such as tensile strength may be deteriorated.If it exceeds the above range, the cost may increase, which may be undesirable. Can have any number.

In addition, the sum (b) may be 5-30 times or 5-20 times. If it is outside the above range, the strength is lowered and the yarn is released at the hole portion of the perforated portion when punching artificial leather, so that the yarn cut in front of and behind the punching hole may be reflected, or mechanical properties such as tensile strength may decrease, so the number may be within the above range.

The circular knitted fabric of the present invention described above may be impregnated with a polyurethane (Poly urethane, PU) solution to prevent yarn loosening during punching and to improve the sewing workability of one end of the automobile seat cover.

At this time, the polyurethane resin content of the impregnated knitted in the ring can be 15-55g / m ² or 20-50g / m ^2. If it is less than the above range, the polyurethane resin cannot hold the yarn, so when punching, the yarn is released from the hole in the hole, so that the yarn cut in front of and behind the punching hole may be visible.If it exceeds the above range, the above-mentioned during thermal processing during the artificial leather manufacturing process The polyurethane resin may be melted and eluted to the outside of the back layer, and thus may be impregnated within the above content range.

The back layer has a density after the impregnation in the polyurethane solution can be 280-380g / m ² or 300-350g / m ^2. If the density of the back layer is less than the above range, the strength decreases and the yarn is released at the hole portion of the perforated portion when punching artificial leather, so that the yarn cut in front and behind the punching hole may be reflected, or mechanical properties such as tensile strength may decrease. If it is exceeded, the cost may increase, which may be undesirable, and thus may have a density within the above range.

In addition, the back layer may have a thickness of 0.4-0.7mm or 0.45-0.65mm. If the thickness of the back layer is less than the above range, the strength decreases, and when punching artificial leather, the yarn is released from the hole portion of the perforated part, so that the yarn cut in front and behind the punching hole may be reflected, or mechanical properties such as tensile strength may decrease. If it is exceeded, the cost may increase as it is formed thicker than necessary, which may be undesirable, and thus may have the above thickness range.

On the other hand, the artificial leather of the present invention is a foam layer sequentially on the top of the back layer, which is a circular knitted fabric using the 5-30 number of ply (b); And a skin layer; may further include.

Hereinafter, each layer will be described in detail.

The back layer may have a coating layer formed on one surface to selectively increase the peel strength with the upper foam layer and further prevent loosening of the yarn.

Specifically, the artificial leather of the present invention can be adsorption-molded using a vacuum during embossing, which will be described later.In this case, unlike the case of forming the embossing using a compression roll embossing, the semi-finished product is not compressed with a large pressure. There may be a disadvantage in that the resin of the foam layer cannot be impregnated into the back layer, so that the peel strength between the back layer and the foam layer decreases. Accordingly, the back layer of the present invention may be formed with a coating layer on one side thereof in order to selectively increase the peel strength with the upper foam layer and further prevent loosening of the yarn.

The coating layer may be formed using, for example, an acrylic adhesive, a polyurethane adhesive, and a coating solution selected from among polyvinyl chloride plastisol. However, since the acrylic adhesive is hard after drying, the microhardness of the artificial leather is increased and the touch is not soft.The polyurethane adhesive is relatively expensive and the material cost is increased, so polyvinyl chloride plastisol can be used. have.

The microhardness is a local hardness for a microscopic specimen having a thickness of about 0.5-1.0mm, and an indentation speed of 1mm/s in the peak hold mode using a microhardness meter (Asker Micro Durometer, model name: MD-1 capa) is applied to the specimen. It means the maximum value immediately after the needle contacts, that is, when the load holding time of the needle is 1s.

The polyvinyl chloride plastisol may include 70-130 parts by weight of a plasticizer and 0.5-10 parts by weight of a curing agent based on 100 parts by weight of the polyvinyl chloride resin.

Specifically, the polyvinyl chloride resin may be a mixed resin comprising 60 to 90% by weight of a vinyl chloride homopolymer and 10 to 40% by weight of a copolymer of vinyl chloride and vinyl acetate.

The vinyl chloride homopolymer is a paste polyvinyl chloride resin prepared by emulsion polymerization, and may be included in an amount of 60-90% by weight or 65-85% by weight in the mixed resin. If it is less than the above range, the peeling strength between the back layer and the foam layer may be slightly lowered or the yarn may be loosened, and if it exceeds the above range, it may be undesirable, such as odor, and may be included within the above range.

The copolymer of vinyl chloride and vinyl acetate is a resin that provides excellent adhesion to the back layer and the foam layer and prevents loosening of the yarn. The content of vinyl acetate in the copolymer is 1-15% by weight or 3 It may be included in -10% by weight. If it is less than the above range, the peel strength between the back layer and the foam layer may be slightly lowered or the yarn may be loosened, and if it exceeds the above range, the hydrolyzability may be lowered, and thus may be included within the above range.

In addition, the copolymer of vinyl chloride and vinyl acetate may be contained in 10-40% by weight or 15-35% by weight in the mixed resin. If it is less than the above range, the peel strength of the back layer and the foam layer may be slightly lowered or the yarn may be loosened, and if it exceeds the above range, mechanical properties such as heat resistance may be slightly lowered, and thus may be included within the above range.

The plasticizer may be at least one selected from a phthalate-based plasticizer, a terephthalate-based plasticizer, a benzoate-based plasticizer, a citrate-based plasticizer, a phosphate-based plasticizer, and an adipate-based plasticizer.

In the present invention, it is possible to use a terephthalate plasticizer that is preferably environmentally friendly and has excellent heat resistance. Dioctyl terephthalate may be used as an example of the terephthalate plasticizer, but is not limited thereto.

The plasticizer may be included in an amount of 70-130 parts by weight or 80-120 parts by weight based on 100 parts by weight of the polyvinyl chloride resin. If it is less than the above range, the viscosity of the coating solution may increase and thus processability may decrease, and if it exceeds the above range, the adhesive strength may decrease due to the transition of the plasticizer, and thus may be included within the above range.

The curing agent may be a low-temperature curing type curing agent to increase energy efficiency and productivity, and a block isocyanate curing agent in which some or all of the isocyanate groups are blocked with a blocking agent may be used.

The blocking agent is phenol, ε-caprolactam, methyl ethyl ketone oxime, 1,2-pyrazole, and diethyl malonate. malonate), diisopropylamine, triazole, imidazole, and at least one selected from the group consisting of 3,5-dimethylpyrazole may be used. .

The block isocyanate curing agent blocks the isocyanate group so that the isocyanate group (-NCO) does not react with the hydroxyl group (-OH) or the amino group (-NH) at room temperature, and when it reaches a certain temperature range, the blocking agent dissociates and the reactivity of (-NCO) This increases and the curing reaction proceeds.

The dissociation temperature of the curing agent may be 100°C or higher or 110-130°C.

The curing agent may be included in an amount of 0.5-10 parts by weight or 1-5 parts by weight based on 100 parts by weight of the polyvinyl chloride resin. If it is less than the above range, the peel strength between the back layer and the foam layer may be slightly lowered due to a decrease in the degree of crosslinking. .

The coating solution may optionally further contain one or more other additives selected from the group consisting of a stabilizer, a filler, a pigment, a viscosity reducing agent, and a dispersing agent, as required, and the content thereof does not affect the physical properties of the coating solution. If it is, there is no limit.

The thickness of the coating layer may be 1-10 μm or 2-5 μm, for example. Here, the thickness of the coating layer means the thickness including the coating solution impregnated into the back layer. If the thickness of the coating layer is less than the above range, the peel strength between the back layer and the foam layer may be slightly lowered or the yarn may be loosened. If the thickness of the coating layer is exceeded, the microhardness of the artificial leather increases and the touch feeling decreases. Can be coated in thickness.

Foam layer

The foam layer of the present invention is to impart soft properties and cushioning feeling to artificial leather, and may include 60-120 parts by weight of a plasticizer and 5-15 parts by weight of a foaming agent based on 100 parts by weight of the polyvinyl chloride resin.

Specifically, the polyvinyl chloride resin may be a straight polyvinyl chloride resin formed by suspension polymerization capable of securing an excellent cushioning feeling, high elongation, and excellent durability at the same time.

The degree of polymerization of the polyvinyl chloride resin may be less than 900-1300, or 950-1250. If it is less than the above range, durability decreases, and if it exceeds the above range, the hardness of the foam layer increases and the cushioning feeling decreases, so a polyvinyl chloride resin having a polymerization degree within the above range may be used.

Optionally, in order to provide adhesion to the back layer and to further prevent loosening of the back layer, the foam layer is prepared by adding a copolymer of vinyl chloride and vinyl acetate to 100 parts by weight of the polyvinyl chloride resin. It may further include 20 parts by weight or 5-15 parts by weight. If it is less than the above range, the peel strength with the back layer is slightly lowered, and if it exceeds the above range, the raw material value increases, which is not preferable, and thus may be included within the above range.

The content of vinyl acetate in the copolymer of vinyl chloride and vinyl acetate may be included in 0.5-10% by weight or 1-5% by weight.

The plasticizer may be one or more selected from the phthalate plasticizer, terephthalate plasticizer, trimellitate plasticizer, and epoxy plasticizer.

The phthalate plasticizer is a plasticizer having very good compatibility with the polyvinyl chloride resin, for example, among dibutylphthalate, diethylhexylphthalate, diisononylphthalate, dipropylheptylphthalate, diisodecylphthalate, and butylbenzylphthalate. It may be one selected, preferably diisodecylphthalate, a low volatility plasticizer, may be used.

The terephthalate-based plasticizer may be an eco-friendly plasticizer, for example, dioctyl terephthalate, but is not limited thereto.

The trimellit-based plasticizer is a plasticizer having excellent volatility, oil resistance, and heat resistance, for example, triethylhexyl trimellitate, triisononyl trimellitate, and triisodecyl trimellitate may be one selected from, but limited thereto. It does not become.

The epoxy plasticizer is an epoxidized double bond of an unsaturated fatty acid glycerol ester with hydrogen peroxide or peracetic acid. For example, epoxidized soybean oil or epoxidized linseed oil may be used, but is not limited thereto.

The plasticizer may be used in an amount of 60 to 120 parts by weight, or 70 to 100 parts by weight based on 100 parts by weight of the polyvinyl chloride resin. If it is less than the above range, workability and ductility may be deteriorated, and if it exceeds the above range, bleeding of the plasticizer may occur, so that a plasticizer within the above content range capable of implementing excellent ductility may be used.

The foaming agent is not particularly limited as long as it can form fine bubbles that impart the necessary elasticity and thickness to the foaming layer, for example, azodicarbonamide (ADCA), p,p'-oxybisbenzenesulfonyl hydra. It may be a chemical blowing agent such as gide (p,p'-Oxybis (benzenesulfonyl hydrazide)), p-toluenesulfonyl hydrazide (p-toluenesulfonyl hydrazide), and sodium bicarbonate.

The foaming agent may be used in an amount of 5-15 parts by weight, or 5-10 parts by weight based on 100 parts by weight of the polyvinyl chloride resin. If it is less than the above range, the softness and cushioning feeling of the artificial leather is deteriorated, and if it exceeds the above range, it is generated by excessive foaming of the foam layer, so that the surface properties and durability are reduced, so that it can be used within the above range.

In addition, the foam layer may further include at least one selected from a heat stabilizer, a flame retardant, and a filler in order to control melt strength and physical properties, and the type and content thereof are not limited.

In addition, the foam layer may have a foaming rate of 100-500% or 150-350%. By having a foaming rate within the above range, volume, cushioning and soft surface texture can be secured.If the amount is less than the above range, the microhardness of the artificial leather increases and becomes hard and exceeds the above range, that is, when excessive foaming occurs. It is preferable to have a foaming rate within the above range because the durability and strength of the artificial leather are weakened and the physical properties are reduced.

In addition, the foam cells may be included in 10-30 per unit area of 1mm ² of the foam layer layer, or 15-20. If it is less than the above range, the ductility and cushioning feeling are deteriorated, and when it exceeds the above range, the surface durability is lowered and physical properties such as surface texture and cushioning feeling are lowered.

The number of foam cells was determined by cutting the artificial leather in a horizontal direction, and then measuring the number of foam cells formed in a unit area of 1 mm ² of the layer surface of the foam layer using an optical microscope.

In addition, the foam layer may have a thickness of 0.4-0.7mm or 0.4-0.6mm after foaming, and if it is less than the above range, the cushioning feel is deteriorated, and if it exceeds the above range, it is formed thicker than necessary, so material cost may be high. In addition, a large number of thick wrinkles may occur, resulting in poor marketability.

Skin layer

The skin layer of the present invention is for securing surface smoothness and realizing color, and may include 60 to 120 parts by weight of a plasticizer and a pigment based on 100 parts by weight of the polyvinyl chloride resin.

Specifically, the polyvinyl chloride resin included in the skin layer may be a straight polyvinyl chloride resin formed by suspension polymerization, and it is preferable to use a polyvinyl chloride resin having a higher degree of polymerization than the polyvinyl chloride resin used in the foam layer. It is preferable to prevent the skin layer from bursting during foam molding.

The polyvinyl chloride resin included in the skin layer may have a degree of polymerization of 1300-3000, or 1300-2000. If it is less than the above range, there is a risk that the skin layer may burst during foam molding, and if it exceeds the above range, the surface texture and ductility may be deteriorated, and thus a polyvinyl chloride resin having a polymerization degree within the above range may be used.

The pigment may be carbon black, but is not limited thereto.

In addition, the skin layer may further include at least one selected from a heat stabilizer, a flame retardant, and a filler to control melt strength and physical properties.

The plasticizer, heat stabilizer, flame retardant, and filler included in the skin layer are the same as the plasticizer, heat stabilizer, flame retardant and filler included in the foam layer described above, so duplicate descriptions will be omitted.

The thickness of the skin layer may be 100-300㎛, or 120-200㎛. If it is less than the above range, the surface smoothness and processability are deteriorated, and the material cost may increase due to an increase in the amount of pigment to implement the color.If it exceeds the above range, the cushioning feeling of the artificial leather decreases and it is thicker than necessary. Accordingly, it may take a lot of material cost, and thus may have the above thickness range.

Optionally, the artificial leather of the present invention may further include a surface treatment layer on top of the skin layer in order to improve stain resistance and simultaneously satisfy the squeak index and the dynamic friction coefficient to improve a soft touch and seating feeling. .

The surface treatment layer may be formed using an aqueous surface treatment agent including 100 parts by weight of the main body, 1 to 25 parts by weight of a curing agent, 1 to 25 parts by weight of an aqueous solvent, and 1 to 15 parts by weight of a silicone compound.

The subject may be a water-dispersed polycarbonate-based polyurethane resin, but is not limited thereto.

The curing agent may include one or more functional groups selected from the group consisting of an aziridine group, an isocyanate group, and a carbodiimide group per molecule.

The silicone compound may be a liquid form in which polysiloxane is dispersed in water or a bead form of polysiloxane, but preferably may be in a liquid form in which the surface feel is better dispersed in water.

When the content of the silicone compound is less than the above range, antifouling properties are lowered, and when the content of the silicone compound exceeds the above range, the surface texture is excessively slipped to minimize the squeak index, but the seating feel is not good because the appropriate level of dynamic friction coefficient is not satisfied. It can be used within the content range.

That is, the artificial leather of the present invention may simultaneously satisfy the squeak index and the dynamic friction coefficient by including the silicone compound in the specific range.

In more detail, the squeak index is a value of noise generated in friction between the artificial leather and the human body, that is, the occupant, and the artificial leather specimens are stacked up and down using a universal testing machine, and a weight of 4.5Kg The squeak index can be calculated as △F/Fa by measuring the deviation (△F) and the average force (Fa) of the force required to press and pull at a speed of 100mm/min.

The squeak index is less than 0.15, or less than 0.14 and satisfies the above range, so that the noise is low and the touch is soft. When the above range is exceeded, since the noise is severe and the stick slip characteristic, which is a friction phenomenon accompanied by vibration, is strong, the squeak index may be within the above range.

The dynamic friction coefficient (μ) is to hold slip properties when an object moves while sliding in contact with another object. Using a universal testing machine, each artificial leather specimen is stacked up and down and pressed with a weight of 4.5 kg (W) and 300 mm/ By measuring the average force (Fa) required to pull at the min speed, the coefficient of dynamic friction can be measured in Fa/W.

The coefficient of dynamic friction may be 0.2-0.5 or 0.25-0.5. If it is less than the above range, the slip property cannot be held and the seating feel is not good, and if the above range is exceeded, the squeak index increases due to friction between the artificial leather and the occupant, so the dynamic friction coefficient may be within the above range.

In addition, the aqueous surface treatment agent of the present invention may further include 0.1-0.5 parts by weight of an antifoaming agent and 1-5 parts by weight of a leveling agent for workability and physical properties, and optionally in the group consisting of urethane beads, acrylic beads, and fluorine-added wax. It may further include one or more selected.

By further including at least one selected from the group consisting of the urethane beads, acrylic beads, and fluorinated wax, antifouling properties may be implemented by hydrophobicity, and slip properties may be further imparted by reducing the surface tension of the aqueous surface treatment agent. .

In addition, depending on the role of the aqueous surface treatment agent, it may further include one or more selected from surfactants, co-solvents, modifiers, matting agents, gloss enhancing agents, thickening agents, and matting agents, and the type and content thereof There is no particular limitation.

The surface crosslinking density of the surface treatment layer is 70-98%, or 75-95%, and by securing the surface crosslinking density within the above range, contaminants cannot penetrate the surface treatment agent and thus have excellent antifouling properties.

For the surface cross-linking density, after weighing an artificial leather specimen to 1 mg with a chemical balance (m ₁ ), place it on a container made of a mesh or perforated metal plate, put the container in boiling xylene or decahydro naphthalene, and leave for 6-8 hours. do. Thereafter, the container with the residue was taken out of the boiling solvent, cooled to room temperature, dried, and the residual amount (m ₂ ) was weighed up to 1 mg and calculated as m ₂ /m ₁ x100.

In addition, the surface tension of the surface treatment layer is 90-130° or 95-120°, and by maintaining the surface tension in the above range, it may have excellent antifouling properties compared to the surface treatment layer formed with an oil-based surface treatment agent.

When the surface tension is applied to artificial leather using a pen (Dynepen) containing a liquid having a specific tension of 20°-60°, if the tension of the liquid is greater than the surface tension of the artificial leather, the liquid does not apply and When the tension of the liquid is less than the surface tension of artificial leather, the liquid is spread flat and spreads well. At this time, the inner angle of the liquid is measured to indicate the surface tension (dyne test). .

The surface treatment layer may have a thickness of 4-30 μm or 4-20 μm. By maintaining the thickness of the surface treatment layer within the above range, it is possible to simultaneously secure contamination resistance while maintaining the flexibility of the artificial leather. If it is less than the above range, the thickness is too thin and durability may be deteriorated. If the thickness is exceeded, the water-based surface treatment agent is required to increase and material cost may be increased, and thus the thickness may be within the above range.

In addition, optionally, the artificial leather of the present invention may further include an embossed pattern on the skin layer and the surface treatment layer to impart a three-dimensional effect.

The tensile strength of the artificial leather of the present invention after punching is 15-30kgf/30mm or 16-20kgf/30mm in the longitudinal direction, and may be 12-24kgf/30mm or 13-20kgf/30mm in the width direction, and by satisfying the above range Mechanical properties can be excellent even after punching.

In addition, the reduction rate of tensile strength before and after punching of the artificial leather of the present invention may be -57% to -15% or -55% to -20% in the width direction, and by satisfying the above range, mechanical properties are excellent even after punching. can do.

In the present invention, the longitudinal direction means the machine direction, that is, Machine Direction (MD), and the width direction means the Transverse Direction (TD) perpendicular to the machine direction.

In addition, the elongation of the artificial leather of the present invention after punching is 55-70% or 59-65% in the longitudinal direction, and may be 150-180% or 156-178% in the width direction. By satisfying the above range, the mechanical Physical properties can be excellent.

In addition, the increase rate of the elongation before and after punching of the artificial leather of the present invention may be 13% to 40% or 15% to 35% in the longitudinal direction, and by satisfying the above range, mechanical properties may be excellent even after punching.

In addition, the static load elongation after punching of the artificial leather of the present invention may be 15-25% or 16.5-23% in the longitudinal direction, and 40-55% or 45-53% in the width direction. By satisfying the above range, even after punching It can have excellent mechanical properties.

In addition, the increase rate of static load elongation before and after punching of the artificial leather of the present invention may be 14% to 55% or 18% to 50% in the width direction, and by satisfying the above range, mechanical properties may be excellent even after punching.

In addition, the residual reduction rate after punching of the artificial leather of the present invention may be 1.5-3.5% or 2-3% in the length direction, and 5-9% or 6-8.5% in the width direction, and by satisfying the above range, punching Even after, the mechanical properties may be excellent.

In addition, the increase rate of the residual reduction rate before and after punching of the artificial leather of the present invention may be 11% to 98% or 20% to 80% in the width direction, and by satisfying the above range, mechanical properties may be excellent even after punching. .

In addition, the tear strength after punching of the artificial leather of the present invention may be 3.8-5.5kgf or 4-5% in the longitudinal direction, and 4.0-5.0kgf or 4.1-4.7kgf in the width direction, and punching by satisfying the above range Even after, the mechanical properties may be excellent.

In addition, the reduction rate of the tear strength before and after punching of the artificial leather of the present invention is -32% to -3% or -30% to -5% in the longitudinal direction, and -14% to -1.1% or- It may be 12% to -1.1%, and by satisfying the above range, mechanical properties may be excellent even after punching.

In addition, the bursting strength of the artificial leather of the present invention after punching may be 9-15kgf/cm ² or 11-13 kgf/cm ² in the longitudinal direction, and by satisfying the above range, mechanical properties may be excellent even after punching.

In addition, the peeling strength of the artificial leather of the present invention after punching is 1.8-5kgf/30mm or 2-4kgf/30mm in the longitudinal direction, 1.8-5kgf/30mm or 2-4kgf/30mm in the width direction, and the above range By being satisfied, mechanical properties can be excellent even after punching.

In addition, the reduction rate of the peel strength before and after punching of the artificial leather of the present invention may be -72% to -30% or -65% to -40% in the longitudinal direction, and by satisfying the above range, mechanical properties are excellent even after punching. can do.

The tensile strength, elongation, static load elongation, residual shrinkage, tear strength, rupture strength, and peel strength are artificial leather as a circular pin type with a diameter of 1.0 mm, and 32 pieces/in ² at intervals of 7 mm in width and 7 mm in length. This is the result of the measurement after punching with a fixed pattern to have a perforation of.

The artificial leather of the present invention includes a back layer, which is a circular knitted fabric using 5 to 30 ply yarns, so that the price is low, there is no hole seepage even after punching, and mechanical properties such as tensile strength are excellent.

The present invention comprises the steps of forming a back layer which is a circular knitted fabric using a number of 5-30 ply; It relates to a method of manufacturing artificial leather comprising a.

The step of forming the back layer is a step of forming a circular knitted fabric by combining 2-4 single yarns (a) having a number of twists of 450-600 tpm of 20-40 times and knitting the twisted yarns (b) with a circular knitting machine.

In addition, the step of forming the back layer may include impregnation in a polyurethane solution to prevent the yarn from loosening after punching after forming the circular knitted fabric.

The PU solution may contain 20-35% by weight of a polyurethane resin, 55-70% by weight of dimethylformamide, and 4-7% by weight of a pigment.

In addition, the step of forming the back layer may optionally further include coating one surface with a coating solution to further prevent loosening of the yarn by increasing the peel strength with the foam layer on the top.

The viscosity of the coating solution may be 80-140 seconds or 100-120 seconds at 25° C. in terms of Zahn cup (#3 cup) viscosity. If it is less than the above range, the coating solution flows down to reduce the coating efficiency, and if it exceeds the above range, the coating solution aggregates during coating and impregnation into the back layer is not well made, so if it is within the above viscosity range, stable processability can be secured. .

In addition, the coating solution may be applied to one side of the back layer by a conventional coating method, and as a specific example, it may be applied through gravure coating, but is not limited thereto.

Subsequently, the coating solution applied to one side of the back layer may be gelled by applying heat at a temperature of 100-150°C.

Other properties of the coating solution are the same as those described above, so a duplicate description will be omitted.

The manufacturing method of the artificial leather of the present invention includes the steps of i) forming the back layer, ii) forming the pre-foaming layer and the skin layer, iii) laminating the back layer on the bottom of the pre-foaming layer, and then stacking the back layer. It may further include laminating a skin layer on top of the pre-foaming layer, and iv) forming a foam layer by foaming the pre-foaming layer.

Hereinafter, each step will be described in detail.

In step ii), the pre-foaming layer and the skin layer may be formed by kneading the pre-foaming layer and the skin layer composition, respectively, and passing them through a calender roll at 160-170°C.

The pre-foaming layer is foamed during foam molding to form a foaming layer. Since the pre-foaming layer composition is the same as the configuration of the foaming layer described above, duplicate descriptions will be omitted. In addition, since the skin layer composition is also the same as that of the skin layer described above, duplicate descriptions will be omitted.

In addition, the back layer from the bottom to the top in step iii); Prefoaming layer; And when the skin layer is laminated, heat plywood may be performed at 150-180°C.

Specifically, the reason why the back layer is thermally laminated on the bottom of the pre-foaming layer and then the skin layer is laminated on the top of the pre-foam layer on which the back layer is laminated is because the back layer has excellent mechanical strength such as tensile strength. This is because each visual layer holds physical properties. If the pre-foaming layer and the skin layer are first laminated, there is a problem that curling, such as bubbles or bending of the layer, occurs during the thermal plywood.Therefore, first, a back layer having excellent mechanical strength such as tensile strength is placed on the bottom of the pre-foaming layer. It may be thermal plywood.

Step iv) is a back layer; Prefoaming layer; It may be a step of forming a foam layer by passing the semi-finished product on which the skin layer is laminated through an oven at 220-240° C. to foam the pre-foam layer.

The manufacturing method of the artificial leather of the present invention may optionally further include the step of forming a surface treatment layer by applying and drying an aqueous surface treatment agent on the skin layer of the semi-finished product that has undergone the foaming process.

Since the aqueous surface treatment agent is the same as described above, a duplicate description will be omitted.

The method of applying the aqueous surface treatment agent may be a method such as gravure coating, knife coating, or bar coating, but is not limited thereto.

In addition, the drying process may evaporate the aqueous solvent by drying at 110-150°C or 130-150°C for 80-120 seconds.

In addition, the method of manufacturing the artificial leather of the present invention may optionally further include the step of forming an embossed pattern, and the embossed pattern may be formed using a press-type roll emboss or a vacuum adsorption roll emboss.

In one embodiment, in the case of forming an emboss pattern using the press-type roll embossing, after the step of iv) forming the foam layer, the skin layer is softened by irradiating infrared rays, and then using the press-type roll embossing 1 After forming the embossed pattern under a pressure of -5Mpa or 2-4Mpa, a step of forming a surface treatment layer by applying an aqueous surface treatment agent may be performed.

This is because if the embossing pattern is formed using a press-type roll emboss after forming the surface treatment layer, a very thin surface treatment layer may be broken by the pressure of the press-type roll emboss. It is preferable to form the surface treatment layer after forming the pattern.

In another embodiment, in the case of forming an emboss pattern using the vacuum adsorption roll embossing, after the step of forming the surface treatment layer, after the step of forming the surface treatment layer, infrared rays are irradiated to heat it, and then 0.02-0.08Mpa using the vacuum adsorption roll embossing Or, it is possible to form an embossed pattern under a vacuum pressure of 0.04-0.07Mpa.

The infrared irradiation step may be a step of irradiating infrared rays for 5-15 seconds or 10-15 seconds at 150-180°C. If infrared rays are irradiated below the above temperature and time, the skin layer is not softened, so that embossing is not formed well, and if infrared rays are irradiated beyond the above temperature and time, the skin layer may melt, so infrared rays can be irradiated within the above time. have.

In addition, the method of manufacturing the artificial leather of the present invention may further include a step of punching. In the punching process, in a specific embodiment, a pin is fixed to a plate-shaped supporter having a width of 160 cm and a length of 10 cm, and the artificial leather passes under the plate-shaped supporter at a speed of about 0.5-2 m/min, and punching may be performed. .

The artificial leather of the present invention may be used for automobile interior materials, specifically, it may be used for a seat cover applied to a car seat, and more specifically, it may be used as a side cover, a bolster, or a main cover.

The artificial leather of the present invention can be used for the main cover in a specific embodiment.

When used as the main cover, for durability, it is preferable to use a compression type roll emboss rather than a vacuum adsorption type roll emboss.

Hereinafter, a preferred embodiment is presented to aid the understanding of the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, It is natural that such modifications and modifications fall within the appended claims.

[Example]

1. Artificial leather manufacturing

<Example 1>

i) A circular knitted fabric was formed by putting the number 15 ply (b) in a circular knitting machine (financial machine/sams machine/ssangyong machine) and knitting. At this time, the plying yarn is a yarn twisted by combining two melange yarns (a) blended with polyester fiber and cotton fiber having a number of twists of 540tpm in a weight ratio of 60-70:30-40. .

Subsequently, the circular knitted fabric was impregnated with a polyurethane solution containing 20-35% by weight of a polyurethane resin, 55-70% by weight of dimethylformamide, and 4-7% by weight of a pigment, so that the polyurethane resin was impregnated in an amount of 40g/m ² The back layer, which is a circular knitted fabric having a thickness of 0.5 mm with a density of 300 g/m ² , was formed.

ii) 10 parts by weight of a copolymer of vinyl chloride and vinyl acetate (LC070, LG Chem) with a vinyl acetate content of 3% by weight per 100 parts by weight of a straight polyvinyl chloride resin (LS100, LG Chem) with a polymerization degree of 1000 , Phthalate plasticizer ^① (DIDP, LG Chem) 80 parts by weight, epoxy plasticizer ^② (Woochang Industries) 5 parts by weight, foaming agent (ADCA) 6 parts by weight, and heat stabilizer (KBZ-270G, KD Chem) 2 parts by weight Pre-foaming layer composition including parts and 100 parts by weight of a straight polyvinyl chloride resin (LS130S, LG Chem) with a polymerization degree of 1300 parts by weight of a phthalate plasticizer ^① (DIDP, LG Chem) 90 parts by weight, an epoxy plasticizer ^② (Woochang Industrial) Company) After kneading the skin layer composition containing 5 parts by weight, 2 parts by weight of pigment (carbon black) and 2 parts by weight of heat stabilizer (KBZ-270G), respectively, passing through a calender roll of 160-170° C., a preliminary thickness of 0.3 mm A foam layer and a skin layer having a thickness of 150 μm were formed.

iii) Subsequently, the back layer, which is the circular knitted fabric formed on the bottom of the pre-foaming layer, is thermally laminated at 150-180°C, and then the skin layer on the top of the pre-foaming layer on which the back layer is laminated is thermally plywood at 150-180°C. I did.

iv) Then, the back layer; Prefoaming layer; A back layer including a foam layer having a thickness of 0.6 mm by passing the semi-finished product on which the skin layer is laminated through an oven at 220° C. to foam the pre-foaming layer at a foaming rate of 170-250%; Foam layer; A semi-finished product in which the skin layer was laminated was formed.

Thereafter, the skin layer was softened by irradiating infrared rays at 150-180° C. for 14 seconds, and then an embossed pattern was formed using a press-type roll embossing under a pressure of 1-5 MPa.

Subsequently, an aqueous surface treatment agent was gravure-coated on the skin layer of the semi-finished product on which the embossed pattern was formed, followed by a drying process at 140° C. for 80-120 seconds to form a surface treatment layer having a thickness of 15 μm, thereby manufacturing artificial leather.

At this time, the water-based surface treatment agent is a curing agent (XR-78-017, Stahl) 5 parts by weight, silicone compound (with respect to 100 parts by weight of water-dispersed polycarbonate-based polyurethane resin (WF-13-549, Stahl)) HM-13-118, Stahl Co.) 5 parts by weight, 20 parts by weight of an aqueous solvent (15 parts by weight of water and 5 parts by weight of isopropyl alcohol), 2 parts by weight of a leveling agent, and 0.2 parts by weight of an antifoaming agent.

<Comparative Example 1>

i) One single yarn (a) with a number of twists of 540tpm of number 30 was put into a circular knitting machine and knitted to form a circular knitted fabric. Subsequently, the circular knitted fabric was impregnated with a polyurethane solution containing 20-35% by weight of a polyurethane resin, 55-70% by weight of dimethylformamide, and 4-7% by weight of a pigment, so that the polyurethane resin was impregnated in an amount of 40g/m ² The back layer, which is a circular knitted fabric having a thickness of 0.5 mm with a density of 200 g/m ² , was formed.

ii) A pre-foaming layer composition comprising 85 parts by weight of a plasticizer, 6 parts by weight of a foaming agent, and 2 parts by weight of a heat stabilizer per 100 parts by weight of a straight polyvinyl chloride resin having a polymerization degree of 1000, and 100 parts by weight of a straight polyvinyl chloride having a polymerization degree of 1000 A skin layer composition including 95 parts by weight of a plasticizer, 2 parts by weight of a pigment, and 2 parts by weight of a heat stabilizer is kneaded and passed through a calender roll at 160-170° C. to form a pre-foaming layer having a thickness of 0.3 mm and a skin layer having a thickness of 150 μm. I did.

In this case, the straight polyvinyl chloride resin, plasticizer, pigment, and heat stabilizer were the same as those in the examples.

iii) Subsequently, the back layer, which is the circular knitted fabric formed on the bottom of the pre-foaming layer, is thermally laminated at 150-180°C, and then the skin layer on the top of the pre-foaming layer on which the back layer is laminated is thermally plywood at 150-180°C. I did.

iv) Then, the back layer; Prefoaming layer; A back layer including a foam layer having a thickness of 0.6 mm by passing the semi-finished product on which the skin layer is laminated through an oven at 220° C. to foam the pre-foaming layer at a foaming rate of 170-250%; Foam layer; A semi-finished product in which the skin layer was laminated was formed.

Thereafter, infrared rays were irradiated at 150-180° C. for 14 seconds to soften the skin layer, and then an embossed pattern was formed using a press-type roll emboss under a pressure of 1-5 MPa.

Subsequently, an oily surface treatment agent was gravure-coated on the skin layer of the semi-finished product on which the embossed pattern was formed, followed by drying at 140° C. for 80-120 seconds to form a surface treatment layer having a thickness of 15 μm, thereby manufacturing artificial leather.

At this time, the oily surface treatment agent contains 95% by weight of urethane acrylate and 5% by weight of methylene dicyclohexyl diisocyanate as a curing agent.

<Reference Example 1>

An artificial leather was prepared in the same manner as in Example 1, except that the following yarn was used as the yarn used to form the back layer, which is a circular knitted fabric.

i) No. 40 ply yarn (b) was put in a circular knitting machine and knitted to form a circular knitted fabric. At this time, the braided yarn is a yarn twisted by combining two melange yarns (a) having a twist number of 80 tpm.

Subsequently, the circular knitted fabric was impregnated with a polyurethane solution containing 20-35% by weight of a polyurethane resin, 55-70% by weight of dimethylformamide, and 4-7% by weight of a pigment, so that the polyurethane resin was impregnated in an amount of 40g/m ² The back layer, which is a circular knitted fabric having a thickness of 0.5 mm with a density of 250 g/m ² , was formed.

<Reference Example 2>

An artificial leather was prepared in the same manner as in Example 1, except that the following yarn was used as the yarn used to form the back layer, which is a circular knitted fabric.

i) The ply yarn (b) having the number 3 was put in a circular knitting machine and knitted to form a circular knitted fabric. At this time, the braided yarn is a yarn that has been twisted by combining two melange yarns (a) having a twist number of 540tpm of the number 6.

Subsequently, the circular knitted fabric was impregnated with a polyurethane solution containing 20-35% by weight of a polyurethane resin, 55-70% by weight of dimethylformamide, and 4-7% by weight of a pigment, so that the polyurethane resin was impregnated in an amount of 40g/m ² The back layer, which is a circular knitted fabric having a thickness of 0.5 mm with a density of 450 g/m ² , was formed.

<Reference Example 3>

An artificial leather was prepared in the same manner as in Example 1, except that the circular knitted fabric was not impregnated with a separate polyurethane solution, and a back layer having a density of 270 g/m ² was used.

2. Measurement of appearance and mechanical properties when punching artificial leather

The artificial leather of Example 1, Comparative Example 1, and Reference Example 1-3 prepared in the above 1 was a circular pin type having a diameter of 1.0 mm, and 32 perforations/in ² were made at intervals of 7 mm in width and 7 mm in length. After punching with a fixed pattern to have it, its appearance and mechanical properties were measured, and the results are shown in Table 1 below.

-The appearance was visually checked to see if the yarn was reflected from the hole in the perforated part. (X: Saga cut through the front and back of the punching hole, Δ: Saga slightly reflected, ○: Saga is not reflected)

-Mechanical properties were measured for tensile strength, elongation, static load elongation, residual shrinkage, tear strength, rupture strength and peel strength.

-For the tensile strength and elongation, a tensile tester (Instron, Shimadzu) was used, and according to MS 300-31, 5 specimens in the horizontal and vertical directions of FIG. 4A were taken, respectively, and a mark (ℓ) of 100 mm was drawn, It is bitten by a testing machine and tensioned at 200mm/min to obtain the maximum weight when the specimen is broken.

The elongation is calculated according to the following equation.

[Equation 1]

L= (L ₁ -L ₀ )/L ₀ X 100

(However, L: elongation (%), L ₀ : distance between gages before test, L ₁ : distance between gages when skin or air bubbles break after test)

-The static load elongation and residual reduction rate were manufactured as specimens of 50 mm width and 250 mm length, respectively, according to MS 300-31, and the length direction (MD) was the width and the width direction (TD) was the width. Each of the three cases is taken and a mark (ℓ ₁ , ℓ ₂ ) of 100 mm distance is drawn in the center of the case (see Fig. 4b). With this clamping interval of 150mm, let it stand for 10 minutes as it is with a static load applied to the fatigue tester to find the distance (L1) between marks. In addition, the test piece is removed from the clamp, the load is removed, and the test piece is left on a flat surface for 10 minutes to obtain the distance (L2) between marks. The static load elongation and residual reduction rate were calculated according to the following equation.

[expression]

Static load elongation (%) = L1-100

Residual reduction rate (%) = L2-100

L1: The distance of the mark after 10 minutes of loading

L2: The distance of the mark after 10 minutes of removing the load

-The tear strength is obtained by manufacturing artificial leather as a specimen of 40 mm in width and 150 mm in length, respectively (see Fig. 4c), and in the case where the length direction (MD) is the width and the width direction (TD) according to MS 300-31. When the width is taken, each of the five specimens is clamped (see Fig. 4d) of a tensile testing machine (Instron, Shimadzu), and the load when tearing to the mark (ℓ) at 200 mm/min is obtained from the average of the maximum values.

-The rupture strength is based on MS 300-31 by using a rupture tester (MULLEN type rupture strength tester) to prepare a specimen of 100 mm in width and 100 mm in length for the artificial leather, and collect 3 pieces in each of the horizontal and vertical directions, Mount the film face down on and apply pressure.

The bursting strength is expressed as the pressure at which the rubber diaphragm breaks through the test piece, and the result is expressed with the average value of three specimens.

-The peeling strength is based on MS 300-31, by preparing a specimen of 30 mm in width and 150 mm in length of artificial leather, collecting 5 pieces in each of the horizontal and vertical directions, and using a solvent such as methyl ethyl ketone (MEK) on the bubble side. After impregnation, the epidermis (foaming layer) and air bubbles (backside layer) are forcibly peeled off by 50 mm in length parallel to the short side, taking care not to apply stress to the epidermis (foaming layer).

After peeling, leave the test piece indoors for at least 2 hours to sufficiently volatilize the solvent, and then fix the peeled skin (foam layer) and air bubbles (back layer) to the clamps of a tensile tester (Instron, Shimadzu), respectively, and 200mm/min. The load when peeling by 50 mm is calculated as the average of the maximum values.

The test result is the average of 5 specimens.

		Example 1		Comparative Example 1		Reference Example 1	Reference Example 2	Reference Example 3	standard
Number of bonds		15		-		40	3	15	-
Number of single yarns/number of twists (tpm)/number of single yarns		30/540/2		30/540/1		80/540/2	6/540/2	30/540/2	-
Whether or not PU impregnation		U		U		U	U	radish	-
Back layer density (g/m 2 )		300		200		250	450	270	-
Properties
		Before punching	After punching	Before punching	After punching	After punching	After punching	After punching	After punching
Exterior		-	○	-	x	x	x	△	○
Tensile strength (kgf/30mm)	L	39	16.86 (-57%)	35	20.98 (-40%)	7.43	14.2	19.1	15 or more
	W	28.03	13.47 (-52%)	26	8.11 (-69%)	12.10	12.56	7.45	12 or more
Elongation(%)	L	48.9	60.38 (+23.5%)	39.28	58.40 (+49%)	58	44.6	60.45	25 or more
	W	127.33	165.34 (+30%)	126	134.88 (+7.0%)	147.5	145.3	155.69	More than 120
Static load elongation (%)	L	12.94	18 (+40%)	10	12.01 (+20%)	7.4	9.3	16.1	6 or more
	W	35.37	48.95 (+38%)	35	84.96 (+143%)	45.32	47.32	47.21	20 or more
Residual reduction rate (%)	L	1.17	2.37 (+103%)	1.20	1.73 (+44%)	2.5	3.3	1.6	4 or less
	W	4.53	7.4 (+63%)	5.52	12.15 (+120%)	13.6	14.2	11.45	14 or less
Tear strength (kgf)	L	5.67	4.1 (-28%)	5.1	3.2(-37.2%)	3.51	3.2	3.48	1.5 or more
	W	4.75	4.7 (-1.1%)	4.00	3.4 (-15%)	2.56	2.6	3.75	1.5 or more
Bursting strength (kgf/cm 2 )	L	17.5	11(-37%)	15	11(-27%)	8	9	11	9 or more
Peel strength (kgf/30mm)	L	6.62	2.48 (-63%)	6.40	1.63 (-75%)	1.54	1.68	1.56	1.8 or higher
	W	3.48	3.3(-5.2%)	4.0	3.51 (-12%)	2.97	2.5	2.87	1.8 or higher

As confirmed in Table 1, Example 1, which is an artificial leather comprising a back layer, which is a circular knitted fabric according to the present invention, has excellent appearance because the yarn cut in front and behind the punching hole is not reflected even after punching (see Fig. 2). , It was confirmed that mechanical properties such as tensile strength were also excellent even after punching.

On the other hand, unlike Example 1, Comparative Example 1, which is artificial leather including the back layer, which is a circular knitted fabric woven using single yarn, not plying yarn, has an unclear appearance due to the transparent yarn cut in front and rear of the punching hole after punching. Compared to 1, mechanical properties such as tensile strength are lowered, and in particular, the values of static load elongation and residual shrinkage are too large, indicating a very dangerous level.

In addition, in Comparative Example 1, the polyvinyl chloride resin included in the foam layer and the polyvinyl chloride resin included in the skin layer had the same degree of polymerization, so the skin layer burst during the foaming step, and the amount of VOC generated by using an oil-based surface treatment agent as a surface treatment agent There are also a lot of odors and a bad smell.

In addition, reference example 1, which is an artificial leather including a back layer, which is a circular knitted fabric formed using a yarn whose thickness is too thin compared to Example 1, and a yarn whose thickness is too thick compared to Example 1 Reference Example 2, which is an artificial leather including a back layer, which is a circular knitted fabric formed by using, is not clear in appearance due to the appearance of the yarn cut in front and behind the punching hole after punching, and mechanical properties such as tensile strength are less than that of Example 1. It was found that the property value of tensile strength was too small, and the property value of the residual reduction ratio was too large.

In addition, Reference Example 3, which is an artificial leather comprising a back layer, which is a circular knitted fabric not impregnated with a separate PU solution, has all omissions, so the appearance is not clean, and mechanical properties such as tensile strength are lowered compared to Example 1. Could know.

Claims (25)

1. Artificial leather that includes the back layer, which is a circular knitted fabric using numbered 5-30 ply yarns (合絲, b).
2. The method of claim 1,

   The synthetic leather (b) is made of 2-4 single yarns (單絲, a).
3. The method of claim 2,

   The single yarn (a) is artificial leather that is spun yarn.
4. The method of claim 3,

   The single yarn (a) is an artificial leather in which polyester fibers and cotton fibers are blended in a weight ratio of 60-70:30-40.
5. The method of claim 4,

   The single yarn (a) is an artificial leather that is a melange yarn.
6. The method of claim 2,

   Artificial leather that the number of twists of the single yarn (a) is 450-600tpm (turns per meter, twist number/1m).
7. The method of claim 2,

   The single yarn (a) is artificial leather that is 20-40 times.
8. The method of claim 1,

   Artificial leather that the content of the polyurethane resin contained in the circular knitted fabric is 15-55g/m ² .
9. The method of claim 8,

   The back layer is artificial leather having a density of 280-380g/m ² and a thickness of 0.4-0.7mm.
10. The method of claim 1,

    The artificial leather is a foam layer sequentially formed on the back layer; Artificial leather that further includes a skin layer.
11. The method of claim 10,

    The artificial leather further includes a surface treatment layer on the skin layer, the squeak index is less than 0.15, and the dynamic friction coefficient (μ) is the artificial leather of 0.2-0.5.
12. The artificial leather of any one of claims 1 to 11 further comprises a punching hole, wherein the tensile strength is 15-30kgf/30mm in the length direction and 12-24kgf/30mm in the width direction.
13. The artificial leather of any one of claims 1 to 11 further includes a punching hole, wherein the reduction rate of tensile strength is -57% to -15% in the width direction compared to before punching.
14. The artificial leather of any one of claims 1 to 11 further comprises a punching hole, wherein the elongation is 55-70% in the length direction and 150-180% in the width direction.
15. The artificial leather of any one of claims 1 to 11 further comprises a punching hole, wherein the increase rate of the elongation is 13% to 40% in the longitudinal direction compared to before punching.
16. The artificial leather of any one of claims 1 to 11 further includes a punching hole, wherein the static load elongation is 15-25% in the length direction and 40-55% in the width direction, and the residual reduction rate is 1.5-3.5 in the length direction. %, artificial leather that is 5-9% in the width direction.
17. The artificial leather of any one of claims 1 to 11 further includes a punching hole, wherein the increase rate of the static load elongation is 14% to 55% in the width direction compared to before punching, and the increase rate of the residual reduction rate is 11% to the width direction. 98% artificial leather.
18. The artificial leather of any one of claims 1 to 11 further comprises a punching hole, wherein the tear strength is 3.8-5.5kgf in the longitudinal direction and 4.0-5.0kgf in the width direction.
19. The artificial leather of any one of claims 1 to 11 further includes a punching hole, wherein the reduction rate of tear strength compared to before punching is -32% to -3% in the length direction and -14% to -1.1% in the width direction Artificial leather that is.
20. The artificial leather of any one of claims 1 to 11 further comprises a punching hole, wherein the rupture strength is 9-15kgf/cm ² in the longitudinal direction.
21. The artificial leather of any one of claims 1 to 11 further comprises a punching hole, wherein the peel strength is 1.8-5kgf/30mm in the longitudinal direction and 1.8-5kgf/30mm in the width direction.
22. The artificial leather according to any one of claims 1 to 11 further comprises a punching hole, wherein the reduction rate of the peel strength compared to before punching is -72% to -30% in the longitudinal direction.
23. The artificial leather of any one of claims 1 to 11 is artificial leather for automobile interior materials.
24. Forming the back layer of any one of claims 1 to 9; Artificial leather manufacturing method comprising a.
25. The method of claim 24,

    After the step i) forming the back layer, ii) forming the pre-foaming layer and the skin layer, iii) laminating the back layer on the bottom of the pre-foaming layer, and then forming a skin layer on the top of the pre-foaming layer on which the back layer is stacked. Laminating, and iv) foaming the pre-foaming layer to form a foaming layer.

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