JPS62110991A - Production of leather-like sheet of high ply separation force - Google Patents

Abstract

PURPOSE:A web of ultrafine fibers is impregnated with an elastic polymer, coated with a binder which can bond to an elastomer as the surface layer, and the surface layer of the elastomer is formed thereon to give the titled sheet with high ply separation force. CONSTITUTION:A mass of fibers which is composed of fibers and/or their bundles in which each fiber can be divided into ultrafine filaments of less than 0.1 denier, is impregnated with an elastomer of, e.g., polyurethane to prepare a porous base. The resultant base (e.g., entangled nonwoven fabric) is coated with a binder which can bond the fibers to the elastic polymer as the surface layer, suitably an adhesive for thermoplastic polyurethane, and solidified. Finally, the sheet is coated with an elastic polymer of thermoplastic polyurethane to form the surface-coating layer. The resultant leather-like sheet has good touch and appearance with large ply separation force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a leather-like sheet having a surface coating layer with high interlayer structure breaking strength.

[Conventional technology]

Conventionally, a method of manufacturing a leather-like sheet having a grain surface 7 (1) by forming an elastic polymer coating layer on one surface of a substrate comprising an elastic polymer in a fiber aggregate is a technique that has already been implemented. For example, Japanese Patent Publication No. 4B-39597, Japanese Patent Publication No. 48
-39829 Publication, Special Publication No. 50-19601,
Japanese Patent Publication No. 59-1822 discloses a manufacturing method in which a polyurethane film, which has been previously formed on a releasable support, is pressed onto a polyurethane-containing substrate while the polyurethane is still sticky. Special Public Service 1987-1787
No. 1 and Japanese Patent Publication No. 60-17872 describe a manufacturing method for forming blood by coating a polyurethane solution or dispersion onto a polyurethane-containing substrate by a gravure method or a reverse roll coater method.

[Problem that the invention seeks to solve]

In the conventional manufacturing method of a leather-like sheet having a grain surface layer by forming an elastic polymer coating layer on one surface of a substrate, the interlayer structure breaking strength (hereinafter referred to as peel strength) particularly near the bonding boundary between the substrate and the surface coating layer is ) is weak. Therefore, in order to improve the peeling strength, a relatively large amount of a solution or dispersion of a non-adhesive elastic polymer such as polyurethane is applied in advance to the surface of the substrate to which the coating layer is to be applied, and it solidifies to a much deeper depth than the surface! :! Improvements have been made using methods such as using a substrate prepared by J″1 in which fibers and resin are embedded together, and using a large amount of strong adhesive to bond a polyurethane film made in advance.

However, although the peeling strength of the leather-like sheet obtained by the conventional method is improved, there are disadvantages such as the leather-like sheet has a hard texture and the shape of the folds and wrinkles on the surface is poor. In particular, when the fibers constituting the fiber aggregate are ultrafine fibers and/or bundles thereof, it is particularly difficult to achieve both peel strength and sensory performance such as texture and appearance.

[Failure to solve the problem]

The present invention provides a method for producing a leather-like sheet that has excellent sensory performance such as texture and appearance, and has high peel strength.

That is, the present invention provides a method for manufacturing a leather-like sheet having a grain layer by forming an elastic polymer coating layer on one surface of a substrate comprising an elastic polymer in a fiber aggregate. and an elastic polymer contained in the fiber aggregate, and a solution or dispersion of a binder that has adhesiveness or affinity with the elastic polymer forming the covering layer. After coating one surface of the substrate and solidifying if necessary, a solution or dispersion of an elastic polymer to form a coating layer is applied to the surface and solidified to form a surface coating layer, resulting in strong delamination. It produces large leather-like sheets.

In particular, in the present invention, the fibers constituting the fiber aggregate have a fineness of 0.
The effect is great when the substrate is made of ultrafine fibers of 1 denier or less and/or bundles thereof, the fiber aggregate is a fiber entangled nonwoven fabric, and the fiber entangled nonwoven fabric contains porous polyurethane.

The fibers constituting the fiber aggregate of the present invention are those normally used for constructing leather-like sheets, and are, for example, single-component polyesters such as polyethylene terephthalate and polybutylene terephthalate, or copolymerized polyesters. Nylon-6, Nylon-66, Nylon-610,
Polyamide or aromatic polyamide such as nylon-11 and nylon-12. Polyacrylonitrile copolymer.

Polyolefins such as polyethylene, polypropylene, and polybutylene. A fiber made of a single polymer such as regenerated cellulose, or a combination of at least two of the above polymers with different properties, or a combination of the above polymer and a soluble or degradable polymer so that at least one of the above polymers becomes a constituent fiber component. Mixed fibers obtained by spinning a combination of different polymers such as polystyrene, copolymerized polystyrene, low polymerized polyethylene, polyester, etc., multicore-sheath composite fibers, split type bonded fibers, and other composite fibers that can be made into axial fibers. The fibers are spun, drawn, and subjected to heat-setting, crimping, cutting, and other treatments depending on the fiber aggregate to be oriented to obtain the desired fibers.

The fineness of the fiber is 3 denier or less, preferably 0.1 denier or less, from the viewpoint of texture, appearance, secondary product processability, etc. when a leather-like sheet is assumed. Conventionally known techniques can be applied as a method for producing fineness for this purpose. For example, Fufutsunyu unsettled, super draw drawing method, splitting method of splitting type fiber, method of dissolving or decomposing and removing one component of mixed fiber or composite fiber, etc.
In order to make a good fiber aggregate, the fiber aggregate is made using mixed fibers, composite fibers, or split type m-fibers, and then subjected to a fibrillation treatment to form a fiber aggregate consisting of ultrafine fiber bundles. The fine fiber treatment is carried out after forming the fiber aggregate, before or after incorporating the elastic polymer.

Next, the m-fiber aggregate of the present invention is a fiber-entangled nonwoven fabric obtained by entangling fibers of a nonwoven web made by random univer or cross wrapper or papermaking method by needle punching and/or high pressure fluid jetting method. This knitted fabric has a web-like surface obtained by raising a knitted fabric with a possible texture.

Further, the elastic polymer to be contained in the fiber aggregate includes polyurethane, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, polyacrylic acid ester or its copolymer, and other synthetic rubbers, but polyurethane is preferable. . Polywanthane is usually used to cover leather-like sheets, for example, average molecular weight,
[This is a polyurethane obtained by reacting a polymer diol of 500 to 3,000, an organic isocyanate, and an organic compound having a molecular weight of less than 500 and having two active hydrogen atoms. Polyurethane is used as a polyurethane solution dissolved in a solvent or a polyurethane dispersion dispersed in a dispersant.
It is impregnated into a fiber aggregate and coagulated using a wet or dry method. The elastic polymer contained in the fiber aggregate is porous! Since it is preferable to have a tank structure because of its properties as a leather-like sheet, a porous structure is created by adding a pore structure regulator, a blowing agent, etc. to the solution or dispersion of the elastic polymer that is impregnated into the fiber aggregate during coagulation. Alternatively, a porous structure can be created by selecting the solidification method or solidification conditions.

For a substrate obtained by incorporating an elastic polymer into a fiber aggregate, the surface on which the coating layer is formed may be the same surface as the substrate was manufactured, but if a smooth surface is desired, the surface of the substrate may be sandpapered. Good results can also be obtained by applying surface treatments, such as puffing the surface with a knife, slicing it with a slicer, or pressing it against a heated smooth metal surface to create a smooth surface.

Next, a binder that improves peel strength is applied to the surface of the substrate of the present invention. The binder has adhesion or affinity with the fibers and elastic polymer that make up the base, as well as the king of the elastic polymers that make up the coating layer.
It is a bend-resistant bonding agent. Examples of the binder include resins mainly composed of acrylic esters or compositions thereof, polyurethane elastomers or compositions thereof, synthetic rubbers or compositions thereof, and the like. In particular, polyurethane elastomers are preferred because they do not cause a large difference in adhesion depending on the type of fiber or elastic polymer, their flexibility can be adjusted arbitrarily, and they have excellent bending resistance. Among them, at least s1m of polymer polyols selected from polyester polyols, polyalkylene ether polyols, polyester/ether polyols, polycaprolactone polyols, etc., and selected from aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc. Particularly preferred is a crosslinking polyurethane obtained by blending at least one type of organic polyol, a low-molecular compound having at least two active hydrogen atoms such as a diamine or triamine, and, if necessary, a reaction accelerator. Further, crosslinking reaction type polyurethane is preferable because it has the advantage that the solvent of the compound before crosslinking reaction does not dissolve the elastic polymer contained in the U&fiber aggregate.

The binder to be applied to the substrate is used in the form of a solution or dispersion in a solvent or solvent composition that does not dissolve or cause decomposition or deterioration of the fibers and elastic polymer. The concentration of the binder and the amount applied to the substrate are changed depending on the fiber density, the content and content of the elastic polymer constituting the substrate, and the strength of the peeling strength, texture,
Optimum conditions can be determined in relation to surface creases, bending resistance, etc., but the general amount of binder applied is 5 to 6097 m'' in terms of solid content.If the amount applied is small, there is no effect. However, if the applied amount becomes too large and a binder film is formed on the surface or the fibers and elastic polymer are embedded in the binder, the effect will be lost.

Methods of applying a solution (f! or dispersion) of the binder to the substrate include methods such as Clavi620-ru coating, reverse roll coating, knife coating, slit coating, and spray coating. Therefore, the concentration of the binder is determined by coating. The binder is selected depending on the method.Furthermore, when the thickness of the substrate is thin or when the entire substrate is to be modified, it is also possible to use a dipping method with a lower binder concentration.

Next, a solution or dispersion of the elastic polymer is applied to the surface of the substrate to which the binder has been applied, and the elastic polymer is solidified by a dry or wet method to form a coating layer. The elastic polymer constituting the coating layer is, for example, a polymer selected from polyvinyl chloride, polyacrylic acid ester/L/or a copolymer thereof, polyurethane or a copolymer thereof, and the like. Preferred is polyurethane or a copolymer thereof. The elastic polymer is applied in the form of a solution or a dispersion, and the elastic polymer applied first is preferably a dispersion (slurry-containing dispersion). The use of a dispersion liquid is preferable because it reduces the possibility of changing the state of the elastic polymer in the substrate, changing the binder, or penetrating the coating liquid into the interior of the substrate to change the texture. However, even a solution of an elastomeric polymer may produce more favorable results depending on the application method. Further, for forming the second and subsequent coating layers, a solution or a dispersion of the elastic polymer may be used. As the coating method, methods such as gravure roll coating, reverse roll coating, knife coating, slit coating, and spray coating can be used. The amount of the surface coating layer applied varies depending on the intended use of the leather-like sheet for the secondary product; for example, a thin coating layer is formed for clothing, gloves, etc., and a thick coating layer is formed for shaft center leather, Nuport products, etc. The amount of coating is determined according to the amount of the coating, but generally the amount is 159 parts m'' to 100 f/- in terms of solid content.

The leather-like sheet of the present invention can be patterned by ordinary embossing, colored by surface gravure coloring method or dyeing method,
The product is made into a finished product through softening treatment.

〔Example〕

Next, embodiments of the present invention will be specifically described with reference to Examples. In addition, parts and percentages in the examples refer to weight unless otherwise specified.

Examples 1 to 3 A web was made using a mixed fiber containing nylon-6 as an island component and soluble polyethylene as a sea component, and needle-punched to create an entangled nonwoven fabric with a basis weight of approximately 1000 f/m.Then, heat treatment was performed. After smoothing the surface, polyester-based polyurethane 15% dimethylformamide (
(hereinafter referred to as DMF) solution is impregnated with a composition solution containing colorants, coagulation regulators, etc., immersed in a non-solvent to coagulate, washed with water, and then treated to dissolve and remove the soluble polyethylene, then dried to produce nylon. The entangled nonwoven fabric is made up of approximately 380 bundles of 6 ultrafine fibers (average fineness o, oos Denny #) and contains approximately 535q/'rn2 of porous polyester polyurethane, and the fibers and polyurethane can be freely deformed without being bonded. A substrate [I] with a soft texture was obtained. Both sides of this substrate were puffed with sandpaper to form a fine raised surface of ultrafine fibers on the surface, and then it was divided into two approximately at the center of the thickness to obtain a substrate (n) each having a thickness of approximately 1.1 mm. .

Next, as a binder, a crosslinked polyurethane composition prepared by blending a polyester diol obtained by reacting adipic acid and glycol with a reaction accelerator mainly composed of aromatic polyisocyanate and polyamine is mixed with a crosslinked polyurethane composition mainly composed of cyclohexanone. A polyurethane composition having a solids content of about 40% was prepared by dissolving the polyurethane in a solvent. The polyurethane composition solution was applied to the puffed surface of the substrate using a knife coating method, and left in a hot air dryer at about 80°C for about 2 minutes to remove the solvent.
%) 100 parts and polyacrylic acid ester emulsion (
An emulsion composition prepared by mixing 100 parts of 25% (concentration 25%) was coated in an amount with a solid content of about 509/+2 using a rubber roll coating method, and then dried in a hot air dryer at about 80°C for about 2 minutes, and then dried at about 120°C. Process for about 2 minutes in a hot air dryer at
A second coating layer was formed. Next, a polyurethane solution consisting mainly of easily dyeable polyurethane is applied to form a finishing layer approximately 25 coats thick, and a leather pattern is embossed to create a leather-like sheet. Table 1 shows the relationship between the amount of binder applied, peel strength, texture, etc.

Table 1 Example 4 A 25% concentration emulsion solution of a polymer containing polyacrylic acid ester/silica was applied to the puffed surface of the base material with a thickness of about 1.1 mm obtained in Example 1 using a roll coating method. The dispersion medium was coated in an amount of approximately 1,597 m'' solid and left in a hot air dryer at approximately 80°C for approximately 3 minutes to remove most of the dispersion medium, and then a surface coating layer was formed in the same manner as in Example 1. Then, embossing was performed to obtain a leather-like sheet.The peel strength of the obtained leather-like sheet was 6.9 kQ/25 width, and it had a texture similar to cowhide, and was suitable for use in cowhide for men's shoes. It was suitable as a material.

〔Effect of the invention〕

The leather-like sheet obtained by the method of the present invention is a leather-like sheet that has a surface coating layer with high interlayer structure breaking strength without impairing sensory performance such as texture and surface crease shape, and is used for clothing, bags, etc. It is used as a material for a wide variety of purposes, including bags, sporting goods, men's shoes, and women's shoes.

Claims (1)

[Claims] 1. When manufacturing a leather-like sheet having a grain layer by forming an elastic polymer coating layer on one surface of a substrate comprising an elastic polymer in the fiber aggregate, the fiber aggregate is A solution or dispersion of a binder that has adhesiveness or affinity with the constituent fibers and the elastic polymer contained in the fiber aggregate, and the elastic polymer forming the coating layer is applied to the fiber aggregate. It is characterized by applying a solution or dispersion of an elastic polymer to form a coating layer on the surface and solidifying it to form a surface coating layer. A method for producing a leather-like sheet with high delamination strength. 2. The manufacturing method according to claim 1, wherein the fibers constituting the fiber aggregate are ultrafine fibers with a fineness of 0.1 denier or less and/or bundles thereof. 3. The manufacturing method according to claims 1 and 2, wherein at least the surface of the fiber aggregate on which the coating layer is formed is in the form of a fiber-entangled nonwoven fabric. 4. The manufacturing method according to claims 1 to 3, wherein the elastic polymer contained in the fiber aggregate has a porous structure. 5. The manufacturing method according to claims 1 to 4, wherein the elastic polymer contained in the fiber aggregate is a thermoplastic polyurethane. 6. The manufacturing method according to claims 1 to 5, wherein the elastic polymer forming the surface coating layer is a thermoplastic polyurethane. 7. The manufacturing method according to claims 1 to 6, wherein the binder is a urethane adhesive.