JP2018053411A - Synthetic leather and method for producing synthetic leather - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic leather that has a soft feeling and an appropriate cushioning property, and a method for producing a synthetic leather that can produce a synthetic leather with high productivity.SOLUTION: There is provided a synthetic leather that comprises a cushion layer and a skin layer in this order on a surface of a raised yarn or pile yarn side of a base fabric having a raised yarn or a pile yarn on at least one surface. The polyurethane includes two or more types of holes selected from a hole with a circular cross-sectional shape, a hole with an oval cross-sectional shape and a hole with an undefined cross-sectional shape and have a different cross-sectional shape to each other. There is also provided a method for producing the synthetic leather.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to synthetic leather and a method for producing synthetic leather.

Automotive interior parts such as instrument panels, door trims, seats, and ceilings, railroad and aircraft interior parts such as trims, seats, and ceilings, furniture, shoes, footwear, bags, interior and exterior components for construction, clothing cover materials and linings, walls Synthetic leather with excellent durability is often used as a material in place of natural leather and fiber sheets. Such synthetic leather has unevenness similar to natural leather on the outermost surface, that is, a wrinkle pattern, and is required to have a soft texture.
In particular, synthetic leather used for automobile seats, chairs and the like has an appropriate cushioning property in addition to a soft texture in order to achieve good sitting comfort. Furthermore, it is said that the synthetic leather preferably has appropriate stretchability and durability.
For this reason, in general, cloth (cloth) is used as a base material, a urethane foam layer is provided on the back surface of the base material to provide cushioning properties, and a skin layer for providing design properties is provided on the surface. Things are used. Hereinafter, in this specification, a cloth (fabric) used as a base material may be referred to as a base cloth.
Synthetic leather with a soft texture is flexible and can be folded easily. However, when it is expanded again from the state of being folded with the skin layer inside, it may be wrinkled and the appearance may deteriorate.

For the purpose of providing a synthetic leather with excellent durability and improved texture, a knitted fabric made of special knitting including raised yarn is used as a base material, and the raised side of the base material is used. There has been proposed a synthetic leather having a urethane adhesive layer and a polyurethane skin layer on the surface, and 20% to 99% of the length of the raised fiber is present in the adhesive layer (see, for example, Patent Document 1). .
The synthetic leather described in Patent Document 1 is manufactured by press-bonding a base fabric and an adhesive layer when the adhesive layer is uncured.
In addition, in order to give a soft texture to the skin layer, it has a wet microporous layer, a polyurethane adhesive layer, and a urethane skin layer as an automotive interior material using wet processing on the raised side of the fabric having raised fibers. And the interior material in which the raising fiber front-end | tip part of a base fabric exists in a polyurethane contact bonding layer is proposed (for example, refer patent document 2).
As a synthetic leather having a voluminous feel without using a wet method, a synthetic leather in which a skin layer is formed on the surface of a fibrous base material having a brushed surface coated or impregnated with a urethane-based resin W / O dispersion has been proposed ( For example, see Patent Document 3).

JP-A-9-111671 JP-A-7-132573 JP-A-6-294077

However, although the synthetic leather described in Patent Document 1 can provide a good texture, for example, there is still room for improvement in cushioning properties for use as a seat.
Moreover, since the interior material described in Patent Document 2 uses a wet method, improvement is seen in terms of volume and texture. However, the wet method includes a step of replacing the dough on which the microporous layer has been formed with a solvent in water, and requires a special processing device. Therefore, from the viewpoint of productivity, a method that does not use the wet method is desired. ing.
The synthetic leather described in Patent Document 3 is easy to manufacture and can be improved in terms of volume and texture, but there is still room for improvement in terms of cushioning properties.
In general, when the base fabric and the cushion layer or the skin layer are bonded via an adhesive layer, it is often necessary to take sufficient curing time to develop the peel resistance, thereby improving productivity. Is required.

An object of one embodiment of the present invention is to provide a synthetic leather having a soft texture and appropriate cushioning properties.
The subject of other embodiment of this invention is providing the manufacturing method of the synthetic leather which can manufacture the synthetic leather which has a soft texture and moderate cushioning property with sufficient productivity.

Means for solving the above problems include the following embodiments.
<1> A base fabric having raised or pile yarn on at least one surface, a cushion layer and a skin layer in this order on the surface on the side having raised or pile yarn, the cushion layer containing polyurethane, Synthetic leather having two or more types of pores having different cross-sectional shapes selected from a pore having a circular cross-sectional shape, a hole having an elliptical cross-sectional shape, and a pore having an indefinite cross-sectional shape in the polyurethane .
<2> The synthesis according to <1>, wherein the pores of the cushion layer include pores having a circular cross-sectional shape derived from a chemical foaming agent and pores having an elliptical cross-sectional shape derived from mechanical foaming. leather.
<3> The synthetic leather according to <1> or <2>, wherein the cushion layer includes pores having an indefinite cross-sectional shape in which two or more pores are connected.
<4> The polyurethane in the cushion layer includes at least one water-based polyurethane selected from the group consisting of polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof. <1> to <3> The synthetic leather as described in any one of these.

<5> A step of forming a skin layer by applying a composition for forming a skin layer on the surface of the release material and drying, and a polyurethane, a chemical foaming agent and a solvent, and having a viscosity of 20,000 mPa · s to 40,000 mPa Preparing a polyurethane-containing composition of s, stirring the obtained polyurethane-containing composition, and preparing a cushion layer-forming composition containing bubbles formed by stirring; and for forming the obtained cushion layer Applying the composition to a surface of the skin layer that does not have a release material, and forming a cushion layer-forming composition layer on the skin layer, the cushion layer-forming composition layer, and at least one surface The base fabric having the raised or pile yarn is closely contacted with the surface having the raised or pile yarn, heat-dried, the chemical foaming agent is foamed, and two or more types of pores having different shapes are provided. Shape cushion layer And a step of the method for producing a synthetic leather.

<6> The cushion layer forming composition is further selected from the group consisting of alkylsulfosuccinate, alkylsulfate, alkylsulfonate, higher fatty acid ester, ether-modified silicone compound, and dimethylpolysiloxane. The method for producing a synthetic leather according to <5>, comprising at least one foam stabilizer.
<7> The step of forming the cushion layer includes forming a hole having a circular cross-sectional shape derived from a chemical foaming agent in the cushion layer, curing the cushion layer, and forming a cushion layer forming composition. The method for producing a synthetic leather according to <5> or <6>, comprising fixing a hole having an elliptical cross-sectional shape formed by mechanical foaming when stirring.

According to one embodiment of the present invention, a synthetic leather having a soft texture and appropriate cushioning properties can be provided.
According to another embodiment of the present invention, it is possible to provide a synthetic leather manufacturing method capable of manufacturing a synthetic leather having a soft texture and an appropriate cushioning property with high productivity.

It is a schematic sectional drawing which shows the synthetic leather which has 2 or more types of void | holes from which a cushion layer mutually differs in shape which is one Embodiment of this invention. It is a schematic sectional drawing which shows the synthetic leather containing the hole of the indefinite shape to which the cushion layer was 2 or more holes which is other embodiment of this invention.

In the present specification, a numerical range described using “to” represents a numerical range including numerical values before and after “to” as a lower limit value and an upper limit value.
In this specification, the term “process” is not only an independent process, but is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes.
Further, in the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means.

Hereinafter, the present invention will be described in detail.
[Synthetic leather]
The synthetic leather of this embodiment comprises a cushion layer and a skin layer in this order on the surface of the base fabric having raised or pile yarn on at least one surface, and the cushion layer. Includes polyurethane, and the polyurethane includes two or more kinds of voids having different cross-sectional shapes selected from pores having a circular cross-sectional shape, pores having an elliptical cross-sectional shape, and pores having an indefinite cross-sectional shape. Has holes.

Although the effect | action of one Embodiment in this indication is not clear, it thinks as follows.
The synthetic leather of the present disclosure has two or more types of holes having different shapes in the cushion layer, so that it can be applied to pressure from different directions as compared to the case of including holes having a single shape. Because it exhibits good cushioning properties and the direction of rebound resilience to stress is diverse, it is considered that it has excellent recoverability not only from pressure on the surface but also when subjected to pressure such as bending It is done.
Further, in a preferred aspect of one embodiment, by having a hole derived from a chemical foaming agent that gives a softer feel and a hole having good rebound resilience due to a hole derived from mechanical foaming, a soft texture is obtained. It is thought that the compatibility with moderate cushioning can be achieved at a higher level.
Furthermore, when the cushion layer is heated and dried, an indefinite shape of pores in which two or more pores are connected to each other may be formed. When the cushion layer has pores with an indefinite shape, for example, when the skin layer is folded with the skin layer inside, the shape of the pores is more easily deformed, and the shape of the pores when the stress is released is reduced. Restorability is better.
For this reason, in synthetic leather with irregularly shaped pores, for example, even when folded with the skin layer inside, when the bending stress is released, the shape of the pores can be easily restored, so that the folded wrinkles are natural. Even if it disappears when left unattended, it has the advantage that it can be easily removed by using a steam iron or the like.

In the synthetic leather manufacturing method of the present disclosure, when the cushion layer is formed, the polyurethane-containing composition contains a chemical foaming agent, and the viscosity of the polyurethane-containing composition is adjusted to the content of the solvent. A composition for forming a cushion-like cushion layer with an appearance having pores due to mechanical foaming by making mechanical foaming easy by stirring by adding a thickener or the like to an appropriate range You can get things. By applying the obtained cushion layer forming composition on the skin layer to form a cushion layer forming composition layer, and further heating and drying the base fabric and the cushion layer forming composition layer, Curing of the composition layer for cushion layer formation, fixation of pores by mechanical foaming by curing of the composition layer for cushion layer formation, and formation of pores derived from the chemical foaming agent by foaming of the chemical foaming agent Can be done. Therefore, it is not necessary to perform the curing process of the adhesive layer, which was conventionally necessary when bonding each layer through the adhesive layer, and it is considered that the productivity has been greatly improved as compared with the conventional method. .
Furthermore, it is possible to form an irregularly shaped hole in which two or more holes are bonded to each other by means such as controlling the temperature during heating and drying. Since the irregularly shaped holes are more easily deformed due to the shape, it is possible to easily manufacture a synthetic leather with better resilience against stress.
Note that the present disclosure is not limited to the above estimation.

Hereinafter, an exemplary embodiment of the present disclosure will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a synthetic leather 10 which is an example of an embodiment.
The synthetic leather 10 of this embodiment uses a base fabric 12 having raised or pile yarn on at least one surface as a base material. In FIG. 1, the raised or pile yarn of the base fabric 12 is not shown.
In the present embodiment, the cushion layer 14 and the skin layer 18 are provided in this order on one side of the base fabric 12. The cushion layer 14 has two types of holes having different shapes, specifically, a hole 16A having a circular cross-sectional shape and a hole 16B having an elliptical cross-sectional shape.
The skin layer 18 provided on the surface of the cushion layer 14 opposite to the side having the base fabric 12 has a leather-like unevenness on the surface that does not contact the cushion layer 14 (hereinafter sometimes referred to as the surface). You may have a pattern, ie, a wrinkle.
In this specification, “provided in this order” means that the cushion layer 14 and the skin layer 18 are present on the base fabric 12 in this order from the base fabric 12 side, and are provided as desired. It does not deny the existence of other layers.

FIG. 2 is a schematic cross-sectional view showing a synthetic leather 20 of another embodiment.
The synthetic leather 20 of another embodiment has the same layer structure as that of the synthetic leather 10 shown in FIG.
In the embodiment shown in FIG. 2, the cushion layer 14 has a hole 16A having a circular cross-sectional shape and an air hole 16B having a circular cross-sectional shape, and further has a hole 16A having a circular cross-sectional shape and an elliptical cross-sectional shape. Among the holes selected from the holes 16B, a hole 17 having an indefinite shape in cross-section is formed by connecting at least two of the holes existing in the vicinity.
The synthetic leather 20 shown in FIG. 2 has the same configuration as that of the synthetic leather 10 shown in FIG. 1 except that the cushion layer 14 is a cushion layer further having an indefinite shape of the holes 17. That is, the base fabric 12 and the skin layer 18 of the synthetic leather 20 are the same as the base fabric 12 and the skin layer 18 in the synthetic leather 10 shown in FIG.
The cross-sectional shape of the pores can be confirmed by observing a cross section of the synthetic leather cut perpendicularly to the surface with a razor using a microscope or a scanning electron microscope (SEM).

[Base fabric]
The synthetic leather in this embodiment has a base fabric having raised or pile yarns on at least one surface. By having raised or pile yarn on at least one surface, the adhesive strength between the adjacent cushion layer and the base fabric becomes good.
The raising | fluff in a base fabric can be formed by a conventional method. For example, raising can be formed by brushing or buffing a knitted fabric having no raising.
As the base fabric having raised brushes, a base fabric having brushed surfaces formed on at least one surface of the double-sided knitted fabric is preferable.
The fabric having pile yarn is a base fabric formed by weaving pile yarn on at least one side of the ground structure constituting the pile fabric. The pile yarn may be a loop pile yarn or a cut pile yarn. When the pile yarn is woven out, it becomes a loop pile yarn, and by cutting the tip of the pile yarn loop, it becomes a cut pile yarn.
The pile fabric has a knitted fabric structure. A loop pile fabric in which the pile yarn has a loop shape (Wana) is formed by regularly lifting a part of the weft of warp double knitting or weft double knitting into a ring shape to form a loop. Can be obtained.

The fibers constituting the base fabric are not particularly limited as long as they have the necessary strength and flexibility.
The fiber used for the base fabric can be appropriately selected depending on the intended use of the synthetic leather. For example, the stretchability of the base fabric is improved by including polyurethane fibers as part of the fibers used for the knitted fabric of the base fabric. Moreover, the intensity | strength of a base fabric improves more by including a polyester fiber, Kevlar fiber, etc.
Especially, it is preferable that a base fabric contains a polyester fiber from a viewpoint of being excellent by durability and a softness | flexibility. Examples of preferable fibers other than polyester fibers include polyamide fibers, Kevlar fibers that are high-strength polyamide fibers, polyurethane fibers, cotton fibers, hemp fibers, rayon fibers, and nylon fibers.

[Cushion layer]
The synthetic leather 10 of this embodiment has a cushion layer 14 adjacent to the base fabric 12 described above. The cushion layer 14 includes polyurethane, and has a plurality of holes 16A and 16B having different shapes from each other in a layer formed by including polyurethane.
In the present specification, the holes having different cross-sectional shapes indicate holes having different outer edge shapes of the cross-section of the holes, such as a circular cross-sectional shape and an indefinite cross-sectional shape. On the other hand, for example, holes having similar cross-sectional shapes such as circles having different diameters are not included in the “holes having different cross-sectional shapes” in this specification.
As an aspect which has a void | hole from which cross-sectional shape mutually differs, the aspect which has hole 16A whose cross-sectional shape is circular and hole 16B whose cross-sectional shape is elliptical can be mentioned, for example.

The holes 16A having a circular cross-sectional shape can be formed using a chemical foaming agent. In the present specification, pores formed by foaming a chemical foaming agent may be referred to as pores derived from the chemical foaming agent. When the chemical foaming agent foams in the cushion layer, pores having a circular cross-sectional shape are easily formed due to gas expansion.
Any known chemical foaming agent can be used. Examples of the chemical foaming agent include thermal expansion microcapsules (hereinafter sometimes referred to as thermal expansion beads), 4,4 "-oxybiz (benzenesulfonylhydrazide) (OBSH), azodicarbonamide (ADCA), sodium hydrogen carbonate. Etc.
A commercially available product may be used as the chemical foaming agent. Examples of commercially available products that can be used in the present embodiment include the foaming agent Neoselbon (registered trademark) series, Neoselbon N # 1000M (trade name: OBSH), Neoselbon SB # 51 (trade name) manufactured by Eiwa Chemical Industry Co., Ltd. Etc.
Examples of the thermally expanded beads include particles obtained by encapsulating an organic solvent such as a hydrocarbon solvent in hollow thermoplastic tree particles. In the thermally expanded beads, the volume of the particles increases due to the volume expansion of the organic solvent by heating, and as a result, bubbles are formed in the polyurethane as a matrix.
Any thermal expansion beads may be used as long as they can expand by heating to form bubbles in the polyurethane matrix and maintain the state of the formed bubbles.
Thermally expanded beads are also available as commercial products, and examples thereof include EXPANSEL series (trade name) manufactured by Nippon Ferrite.
The cushion layer forming composition may contain only one type of chemical foaming agent, or may contain two or more types.

The holes 16B having an elliptical cross-sectional shape can be formed by mechanical foaming. That is, the polyurethane-containing composition is mechanically stirred to form bubbles in the composition, and then heated and dried to fix the bubbles as pores 16B in the cushion layer. The composition used for forming the cushion layer may be a cushion layer forming composition further containing the chemical foaming agent described above. Bubbles formed by mechanical foaming in the cushion layer are formed by applying a shearing force to a composition having a relatively high viscosity, so that air holes having an elliptical cross-sectional shape are easily formed.
In order to obtain stable and uniform air bubbles, in the composition for forming a cushion layer, the amount of the solvent for dissolving the polyurethane is controlled so that the viscosity of the polyurethane-containing composition at 25 ° C. is from 10,000,000 mPa · s to 8.0. It is preferable to adjust to 10,000 mPa · s, and it is more preferable to adjust to 10,000 to 40,000 mPa · s.

In addition, when the cushion layer is heated and dried, for example, by controlling the heating temperature to, for example, 120 ° C. to 190 ° C. or by adding a foaming auxiliary agent, an irregular shape in which two or more pores are connected to each other is used. Voids can be formed.
When the cushion layer has irregularly shaped holes, the irregularly shaped holes are more easily deformed when stress is applied compared to, for example, circular holes, and when the stress is released. Since the restorability of the shape of the holes becomes better, it is preferable.

The cushion layer 14 includes polyurethane.
The polyurethane may be either water-based polyurethane or solvent-based polyurethane, and can be appropriately selected and used according to the purpose. The water-based polyurethane in this specification is used in the meaning including an aqueous dispersion of polyurethane.

As the polyurethane in the cushion layer, solvent-based polyurethane is preferable.
The solvent-based polyurethane preferably includes at least one solvent-based polyurethane selected from the group consisting of polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof.
Among these, when the synthetic leather requires long-term durability, polycarbonate-based polyurethane is preferable.

  Preferable examples of the solvent-based polyurethane include a mode in which a solvent-based blocked isocyanate-based polyurethane is used as a main material and an amine is used in combination. By using the amine together, the blocking agent is dissociated during the heat curing of the polyurethane, and a crosslinked structure can be formed in the polyurethane, which can further improve the film strength and rebound resilience of the resulting cushion layer containing polyurethane. it can.

Polyurethanes may be used to form the cushion layer 14 is preferably made hardness of polyurethane capable of forming a film in the range of ^50N / cm ^{2 ~1200N} / cm 2 at 100% modulus, 98 N / ^cm 2 ~ more preferably in the range of 1176N / cm ^2, more preferably in the range of ^{98N / cm 2 ~490N / cm 2} .
Moreover, it is preferable that the weight average molecular weight of the polyurethane which can be used for formation of the cushion layer 14 is the range of 250,000-1500,000. Catalog values are used for the weight average molecular weight.
The cushion layer may contain only one type of polyester or two or more types.

The cushion layer can contain other components in addition to polyurethane and chemical foaming agents.
Examples of the additive that can be used for the cushion layer include a flame retardant, a foam stabilizer, a crosslinking agent, a crosslinking accelerator, and a film forming aid.
For example, when the composition for forming a cushion layer contains a phosphorus-based flame retardant, the flame retardancy of the synthetic leather is improved. However, if the content of the flame retardant is too high, the flexibility of the resulting cushion layer may be reduced, so the content when using the flame retardant is the total solid content contained in the cushion layer forming composition. It is preferable that it is 20 mass% or less with respect to.

The synthetic leather of this embodiment may have a plurality of cushion layers. When it has a plurality of cushion layers, the composition of each cushion layer may be the same or different from each other.
When it has a plurality of cushion layers, if one of them is the cushion layer in the above-described embodiment, the other cushion layers may have a known configuration.

  There is no restriction | limiting in particular in the thickness of a cushion layer, According to the intended purpose of using synthetic leather, it determines suitably. In particular, from the viewpoint of easily exhibiting a soft texture and appropriate cushioning properties, generally, the thickness including pores is preferably 25 μm to 400 μm, and preferably 50 μm to 300 μm. More preferred. In addition, when it has several cushion layers, it is preferable that the sum total of the thickness of several cushion layers is the said range.

(Skin layer)
The synthetic leather 10 of this embodiment has a skin layer 18 on the surface opposite to the surface of the cushion layer 14 that contacts the base fabric 12 described above.
The skin layer 18 can be provided with design properties according to the intended use of the synthetic leather. There is no restriction | limiting in particular in the formation method of the skin layer 18, A skin layer can be provided by applying the formation method of the skin layer used for a well-known synthetic leather.

There is no restriction | limiting in particular in the synthetic resin used for formation of the skin layer 18, According to the objective, it can select suitably. Examples of the synthetic resin used for forming the skin layer include polyurethane, vinyl chloride resin, acrylic resin, polyester, and the like. Especially, it is preferable that polyurethane is included from a viewpoint that durability and elasticity are favorable and adhesiveness with the adjacent cushion layer 14 becomes more favorable.
Examples of the polyurethane used to form the skin layer 18 include polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof.
From the viewpoint that the synthetic leather of this embodiment is used for applications that require long-term durability, such as automobile seats and chairs, polycarbonate-based polyurethane is preferred.
A commercially available product may be used as the polyurethane. For example, Crisbon [trade name] manufactured by DIC Corporation is preferably used.

When polyurethane is used for the formation of the skin layer 18, the polyurethane has a hardness measured according to JIS K 6301 of 100 N modulus and 49 N / cm ^{2 to} 980 N / cm ² , preferably 196 N / cm ^2. ˜588 N / cm ² is preferred.
In addition, as a method of adjusting the hardness (100% modulus) of polyurethane, for example, when softening, when increasing the polyol component ratio to be a soft segment or increasing the molecular weight of the polyol, Hardening urethane bonds and urea bonds, which are hard segments, and cross-linking agents such as hexamethylene diisocyanate (HDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI) And a method of adding energy to form a cross-linked structure.

The thickness of the skin layer 18 is appropriately selected according to the purpose of use of the synthetic leather. For example, when the skin layer 18 contains polyurethane, the range of 10 μm to 100 μm is preferable, and the range of 20 μm to 80 μm is more preferable.
Moreover, when the skin layer 18 contains a vinyl chloride resin, the range of 0.1 mm-1.0 mm is preferable, and the range of 0.2 mm-0.6 mm is more preferable.

On the surface of the skin layer 18, an arbitrary uneven pattern (drawing: grain) such as leather can be provided.
A method for forming the aperture will be described later in the column of the manufacturing method.

  In the skin layer, in addition to the resin as the main material, for example, polyurethane, as long as the effects of this embodiment are not impaired, it is used for synthetic leather for the purpose of imparting various functions such as designability, feel improvement, strength improvement, etc. Known additives may be added.

Examples of the additive that can be contained in the skin layer include a crosslinking agent, a crosslinking accelerator, a colorant, a feel improver, a film forming aid, a flame retardant, and a foaming agent.
For example, the design property is improved when the skin layer contains a colorant. Moreover, the flame retardance improvement of a skin material can be aimed at by adding well-known flame retardants, such as a phosphorus type | system | group, a halogen type | system | group, and an inorganic metal type.

[Other layers]
The synthetic leather 10 and 20 of the present embodiment is not limited to the above-described cushion layer 14 and skin layer 18 provided on at least one surface of the base fabric 12, and other layers as long as the effects of the present embodiment are not impaired. May be provided.
Examples of the other layers include an adhesive layer for improving adhesiveness, a surface treatment layer for controlling any of the surface physical properties and appearance of the skin layer, and the like.

(Adhesive layer)
An adhesive layer can be provided between the skin layer 18 and the cushion layer 14 in the synthetic leather 10 of the present embodiment.
There is no restriction | limiting in particular as an adhesive agent which can be used for formation of an adhesive bond layer, The adhesive agent containing a polyurethane, a vinyl chloride resin, an acrylic resin, etc. are mentioned.
More specifically, for example, (1) a two-component curable polyester adhesive, (2) a two-component curable polyurethane adhesive, (3) a two-component curable acrylic pressure-sensitive adhesive, and the like are preferable.
In addition, the adhesive agent used for formation of an adhesive bond layer is also available as a commercial item, for example, adhesive no. 3660 [Two-component curable polyurethane adhesive: No Tape Industry Co., Ltd.], Daikarak 7250NT [Two-component curable polyester adhesive: Daido Kasei Kogyo Co., Ltd.], TA265 [Two-component curable polyester adhesive: DIC Corp. ), Crisbon TA205 [polycarbonate polyurethane adhesive: DIC Corporation] and the like are suitable.

As an aspect having an adhesive layer, for example, the cushion layer forming composition is applied to the skin layer 18 and dried to provide the cushion layer 14, and the surface of the obtained cushion layer is bonded to the surface for forming the adhesive layer. A method can be used in which the cushion layer 14 is formed by applying an agent, and then closely adhering to the base fabric 12 preferably by a wet laminating method and heating and drying. In this embodiment, the synthetic leather which has the cushion layer 14 and the skin layer 18 can be obtained on the base fabric 12 through an adhesive layer.
When the synthetic leather takes an aspect in which the cushion layer, the skin layer, and the adhesive layer are bonded, a curing time for heat-curing the adhesive layer is required in the synthetic leather manufacturing process.

(Surface treatment layer)
The surface treatment layer can be formed by applying a surface treatment agent composition containing an aqueous emulsion resin or an organic solvent surface treatment agent composition to the surface of the skin layer 18.
Any resin may be used as the resin used for forming the surface treatment layer. As the resin used for forming the surface treatment layer, for example, polyurethane, acrylic, elastomer and the like are preferable, and polyurethane is more preferable.
By forming the surface treatment agent layer on the surface of the skin layer, the appearance is further improved.
The surface treatment layer can contain a crosslinking agent, an organic filler, a lubricant, a flame retardant, and the like. For example, when the surface treatment layer contains an organic filler, a lubricant, etc., a smooth feel is imparted to the skin material, and the wear resistance is further improved.

  Since the synthetic leather of the present embodiment has the above-described configuration, it has a soft texture and appropriate cushioning properties, and according to a more preferred embodiment, there is an advantage that wrinkles due to bending disappear quickly. For this reason, the synthetic leather of this embodiment is used in various applications, for example, automobile interior parts, railway vehicle interior parts, aircraft interior parts, furniture, shoes, footwear, bags, interior / exterior members for building, clothing cover materials and linings, It can be suitably used for wall coverings and the like.

[Production method of synthetic leather]
The synthetic leather production method of the present embodiment includes a step of forming a skin layer by applying a skin layer-forming composition on the surface of the release material and drying it, and a polyurethane, a chemical foaming agent and a solvent. And a viscosity of 10,000 mPa · s to 40,000 mPa · s is prepared, and the resulting polyurethane-containing composition is stirred, and the composition for forming a cushion layer containing bubbles formed by stirring is prepared. The step of preparing the product [Step (B)] and the obtained composition for forming the cushion layer are applied to the surface of the skin layer which does not have a release material, and the composition layer for forming the cushion layer is formed on the skin layer. Heating the step [Step (C)], the cushion layer forming composition layer, and the surface of the base fabric having raised or pile yarn on at least one side thereof, and having the raised or pile yarn side. Dry, foam the chemical blowing agent, Has a step of forming a cushion layer having the shape of two or more different pores have [step (D)], the.
Each process will be described sequentially.

[Process for forming a skin layer by applying a composition for forming a skin layer on the surface of the release material and drying it: Step (A)]
In the step (A), a skin layer forming composition is applied to the surface of the release material.
The composition for forming a skin layer contains a resin as a main material, for example, polyurethane, vinyl chloride resin, acrylic resin, polyester and the like. In the synthetic leather manufacturing method of the present embodiment, the skin layer forming composition preferably contains polyurethane. When the composition for forming the skin layer contains polyurethane, the durability and elasticity of the synthetic leather become better, and the adhesion with the adjacent cushion layer becomes better. The polyurethane may be either water-based polyurethane or solvent-based polyurethane, and can be appropriately selected and used according to the purpose.
Examples of the polyurethane include polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof. When long-term durability is required, polycarbonate-based polyurethane is preferable.

  The polyurethane in the composition for forming a skin layer may be used alone or in combination of two or more. For example, a polycarbonate-based polyurethane, which is a preferred polyurethane, and a polyurethane other than the polycarbonate-based polyurethane may be used in combination.

As the water-based polyurethane, a polyether- or polycarbonate-based water-based polyurethane homopolymer or a mixture or copolymer of a polyether-based polyurethane and a polycarbonate-based polyurethane is used as a part of the molecular chain of the urethane main agent. A polyurethane into which carboxyl groups of 0.01% to 10%, preferably 0.05% to 5%, more preferably 0.1% to 2% are introduced by mass ratio with respect to the main agent. When a carboxyl group is introduced in the mass ratio range described above, the water-based polyurethane can have sufficient water dispersibility and dry film formability due to the presence of the carboxyl group.
Examples of the solvent-based polyurethane include at least one solvent-based polyurethane selected from the group consisting of polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof that are soluble in an organic solvent. The solvent-based polyurethane may be a one-component system or a two-component system.

Moreover, it is preferable that a polyurethane has a crosslinked structure after hardening from a viewpoint that the film | membrane intensity | strength of the formed skin layer becomes better.
For example, an embodiment in which a crosslinked structure is introduced into an aqueous polyurethane can form a crosslinked structure by reacting a carboxyl group with a crosslinking agent, for example, by using a polyurethane main component having a carboxyl group introduced therein. .
Examples of the crosslinking agent that can be used in the composition for forming the skin layer in order to form a crosslinked structure include conventionally known crosslinking agents. Examples thereof include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a carbodiimide crosslinking agent, and an oxazoline-based crosslinking agent. Among these, it is preferable to use a carbodiimide crosslinking agent from the viewpoint of suppressing polyurethane hydrolysis.

  Moreover, if the aspect which introduce | transduces a crosslinked structure into solvent type polyurethane is mentioned as an example, the aspect which uses solvent type block isocyanate type polyurethane as a main material and uses together with the amine as a crosslinking component will be mentioned, for example. By using the amine in combination, the blocking agent is dissociated during the heat curing of the polyurethane, and a crosslinked structure can be formed in the polyurethane.

The composition for forming a skin layer may further contain other components in addition to the resin as the main material and the solvent.
Examples of other components that can be included in the composition for forming a skin layer include a crosslinking agent, a colorant, and a feel improver.

The composition for forming a skin layer may contain a colorant.
Examples of the colorant include colored organic resin particles in which a colorant is contained in organic resin fine particles selected from urethane resin particles, acrylic resin particles, silicone resin particles, and the like. From the viewpoints of affinity and uniform dispersibility with respect to the polyurethane-based resin, it is preferable to contain polycarbonate-based colored resin particles.
In general, the average particle diameter of such organic resin fine particles is preferably in the range of 0.5 μm to 100 μm, more preferably in the range of 3 μm to 50 μm.

There is no restriction | limiting in particular in the method of providing a skin layer forming composition to a mold release material surface, A well-known providing method is applicable. Examples of the application method include a method of applying with a hermetic or open coating head.
There is no restriction | limiting in particular in the application quantity of the composition for skin layer formation, and the film thickness of the formed skin layer, According to the objective, it selects suitably.
It is generally, the strength and in terms of appearance, as the coating amount before ^drying, in the range of 50g / ^{m 2} ~300g / m 2 are ^preferred, the range of 150g / ^{m 2} ~250g / m 2 Is more preferable.

The skin layer-forming composition can be dried by a known method.
As drying conditions, a temperature of 80 ° C. to 150 ° C. is preferable, and 90 ° C. to 120 ° C. is more preferable. The drying time under this temperature condition can be 1 minute to 5 minutes, and preferably 2 minutes to 3 minutes.
As described above, the thickness of the skin layer after drying when the skin layer 18 includes polyurethane is preferably in the range of 10 μm to 100 μm, and more preferably in the range of 20 μm to 80 μm.
Further, the thickness of the skin layer when the skin layer 18 contains a vinyl chloride resin is preferably in the range of 0.1 mm to 1.0 mm, and more preferably in the range of 0.2 mm to 0.6 mm.

A constriction can be formed on the surface of the skin layer.
As a method of forming the drawing, after forming a skin layer forming composition layer on the surface of the drawing-type transfer release material on which the drawing has been previously formed, and heating and drying to obtain a skin layer having a drawing formed on the surface The cushion layer forming composition is applied to form a cushion layer forming composition layer, and the base fabric 12 is adhered and heat-dried, and then the drawing transfer release material is peeled off. it can.
The method for applying the resin composition for forming the skin layer on the surface of the release material for drawing transfer may be a method of applying the resin composition for forming the skin layer on the surface of the release material for drawing transfer and drying it. If there is no hindrance, a transfer method may be used.

Any method known in the art can be applied to the method of providing the skin layer forming composition layer on the surface of the release material or the drawing transfer release material.
The drawing transfer release material may be any material as long as the desired drawing shape is formed. For example, a commercially available product may be used, or the release material may be obtained by computer graphics or the like. You may use what formed the pattern for desired drawing on the surface.

As another method for forming the constriction on the surface of the skin layer 18, the cushion layer 14 and the skin layer 18 are formed on the base fabric 12, or the laminate including the skin layer 18 and the base fabric 12 are brought into close contact with each other. A method of forming the film by heat-drying and curing the cushion layer 14 and then heat-pressing a drawing type transfer roll having a drawing.
Thus, in the step (A), a skin layer is formed on the surface of the release material.

[Bubbles formed by preparing a polyurethane-containing composition containing polyurethane, a chemical foaming agent and a solvent and having a viscosity of 20,000 mPa · s to 40,000 mPa · s, stirring the resulting polyurethane-containing composition, and stirring. Step of preparing a composition for forming a cushion layer in which the step is contained: Step (B)]
In the step (B), first, a polyurethane-containing composition containing a polyurethane, a chemical foaming agent and a solvent and having a viscosity of 20,000 mPa · s to 40,000 mPa · s is prepared.
By adding a chemical foaming agent to the polyurethane and controlling the content of the solvent, the viscosity of the composition at 25 ° C. is 20,000 mPa · s to 40,000 mPa · s, preferably 25,000 mPa · s to Adjust to 35,000 mPa · s.
The viscosity can be measured using a commercially available BH type viscometer such as a viscometer Viscotester VT-04F manufactured by RION. In this specification, the viscosity is a value measured at room temperature (25 ° C.) using the BH viscometer.

Examples of the solvent that can be used in the polyurethane-containing composition include dimethylformamide (DMF) and ethyl acetate.
When preparing a polyurethane-containing composition containing a polyurethane, a chemical foaming agent and a solvent and stirring, a foaming agent, a foam stabilizer, a cross-linking agent, a thickener, etc. are added as desired to form a cream-like machine. A foamed cushion layer forming composition is obtained.
The polyurethane content relative to the total solid content of the polyurethane-containing composition is preferably 50% by mass to 80% by mass, and more preferably 60% by mass to 80% by mass.

As the chemical foaming agent, the components described above can be used.
The content of the chemical foaming agent with respect to the total solid content of the polyurethane-containing composition is preferably 0.5% by mass to 5.0% by mass, and more preferably 0.5% by mass to 2.5% by mass. preferable.

  The polyurethane-containing composition comprises at least one foam stabilizer selected from the group consisting of alkylsulfosuccinate, alkylsulfate, alkylsulfonate, higher fatty acid ester, ether-modified silicone compound, and dimethylpolysiloxane. It is preferable to contain.

The foam stabilizer is a compound used to prevent bubble breakage by lowering the surface tension of the bubble film during bubble generation and to achieve stable and uniform refinement of bubbles. As the foam stabilizer, as described above, alkylsulfosuccinate, alkylsulfate, alkylsulfonate, higher fatty acid ester, ether-modified silicone compound, dimethylpolysiloxane and the like are preferable. From the viewpoint of improving the properties, dimethylpolysiloxane is preferred.
0.1 mass part-10 mass parts are preferable with respect to 100 mass parts of polyurethane-containing compositions, and, as for the addition amount of a foam stabilizer, 1 mass part-5 mass parts are more preferable.

While stirring, the polyurethane main agent is added with the aforementioned foam stabilizer, cross-linking agent, etc., if desired, and stirring is continued.
When a mechanical stirrer is carried out while entraining air using a known batch stirrer such as a Hobart mixer, a hopper, a planetary mixer or the like, a composition for forming a cushion layer, which is a cream-like mechanically foamed dispersion, is obtained.
From the viewpoint of productivity, it is also preferable to use a method of stirring continuously while supplying a fixed amount of air using an Oaks mixer, a pin mixer, a planetary mixer or the like.

[Step of applying the obtained cushion layer forming composition to the surface of the skin layer that does not have a release agent and forming the cushion layer forming composition layer on the skin layer: Step (C)]
In the step (C), the cushion layer forming composition layer obtained in the step (B) is applied to the surface of the skin layer obtained in the step (A) that does not have a release material.
As a method for applying the mechanically foamed cushion layer forming composition to the skin layer, a known coating method can be applied. As the coating device, known coating devices such as a knife coater, a comma coater, a roll coater, and a lip coater can be used.
When a thicker cushion layer is provided, application may be performed a plurality of times.

There is no restriction | limiting in particular in the application quantity of the composition for cushion layer formation, According to the objective, it selects suitably. It is generally, the strength and in terms of appearance, as the coating amount before ^drying, in the range of 25g / ^{m 2} ~500g / m 2 are ^preferred, the range of 25g / ^{m 2} ~300g / m 2 Is more preferable.

[Cushion layer forming composition layer and the surface of the base fabric having raised or pile yarn on at least one side are closely adhered and dried by heating to foam the chemical foaming agent. And forming a cushion layer having two or more types of holes having different shapes from each other: Step (D)]
In the step (D), first, the cushion layer forming composition layer formed on the skin layer obtained in the step (C) is brought into close contact with the base fabric. By adhering the cushion layer forming composition layer to the surface of the base fabric having the raised or pile yarn, at least a part of the raised or pile yarn is located in the cushion layer forming composition layer. The adhesion between the layer and the base fabric is improved, and the peel strength is further improved.
The cushion layer forming composition is cured and the cushion layer is formed by heating and drying the cushion layer forming composition layer in close contact with the surface of the base fabric having the raised or pile yarn.
Heating and drying can be performed by a conventional method.
The heating means used in heat drying may be non-contact heat drying means such as hot air drying or drying in a heat drying furnace, or may be contact heating means such as contacting a heat roll from the release material side. Good.
The heating and drying temperature is preferably a temperature at which the base fabric 12 and the skin layer 18 are not affected and the cushion layer 14 is cured and the chemical foaming agent is rapidly foamed.
As heat drying temperature, the range of 100 to 250 degreeC is preferable, for example, the range of 90 to 200 degreeC is more preferable, and the range of 100 to 180 degreeC is more preferable.
The heat drying time is preferably 0.5 minutes to 10 minutes and more preferably 1 minute to 5 minutes under the above temperature conditions.
In addition, the temperature conditions and drying time conditions in heat drying should be selected appropriately depending on the synthetic resin used for forming the skin layer and cushion layer, the type of chemical foaming agent, the type of fiber used for the base fabric, etc. That's fine.

In the step (D), the solvent contained in the cushion layer forming composition is removed by heat drying, the crosslinking reaction in the cushion layer proceeds, and the cushion layer is cured. By hardening the cushion layer, the pores derived from mechanical foaming in the cushion layer forming composition layer are fixed. Further, the cushion layer and the skin layer, and the cushion layer and the base fabric are in close contact with each other.
Furthermore, the chemical foaming agent contained in the cushion layer forming composition layer is foamed by heating, and a spherical shape derived from the chemical foaming agent, that is, a hole having a circular cross-sectional shape is formed in the cushion layer.
That is, in the synthetic leather manufacturing method of the present embodiment, the step of forming the cushion layer is to form a hole having a circular cross-sectional shape derived from the chemical foaming agent in the cushion layer, and to cure the cushion layer, The cushion layer forming composition includes the step of fixing an elliptical hole having a cross-sectional shape formed by mechanical foaming when stirring the cushion layer forming composition, so that a cushion layer having a soft and good restorability can be efficiently formed. be able to.

That is, in the step (D), formation of a cushion layer having holes derived from a chemical foaming agent and holes derived from mechanical foaming, and adhesion between the skin layer and the base fabric adjacent to the cushion layer can be performed.
Accordingly, the surface on the side having the raised or pile yarn of the base fabric having the raised or pile yarn on at least one surface by the aforementioned step (A), step (B), step (C) and step (D). In addition, a synthetic leather comprising a cushion layer having two or more types of pores having different shapes in polyurethane and a skin layer in this order can be produced with high productivity.

In the case of using a drawing-type transfer release material for forming a drawing in the skin layer, the surface layer 18 having a drawing type on the surface is obtained by peeling the drawing-type transfer release material after the above-described heat drying. Is formed.
As described above, the method of forming the aperture on the surface of the skin layer 18 is not limited to this.

  According to the method for producing synthetic leather in the present disclosure, a cushion layer and a skin layer are provided in this order on the surface of the base fabric having raised or pile yarn on at least one surface, on the side having the raised or pile yarn. The synthetic leather according to this embodiment, in which the cushion layer has two or more types of pores having different shapes in polyurethane, can be produced with high productivity. In particular, the synthetic leather of this embodiment has a soft texture and good cushioning properties, and due to its layer structure, each layer has high peel strength and good durability even without an adhesive layer. It is. For this reason, in the case of producing a synthetic leather that does not have an adhesive layer that is an arbitrary layer, the curing process of the adhesive layer that is usually performed in the production of synthetic leather is not required, and thus the productivity is superior. It becomes a manufacturing method.

Hereinafter, the present invention will be specifically described with reference to examples. The following examples are merely examples of embodiments of the present invention, and the present invention is not limited to the following examples.
Unless otherwise specified, the following “%” and “part” are based on mass.

[Example 1]
Crisbon (registered trademark) NY324 (manufactured by DIC Corporation, water-based polyurethane) was diluted with a solvent (dimethylformamide: DMF) in an amount of 15% solid content to prepare a composition for forming a skin layer. The obtained composition for forming the skin layer was coated on the surface of the release paper ARX196M (trade name, manufactured by Asahi Roll Co., Ltd.) with a knife coater, and the coating amount was 200 g / m ² and heated in a drying furnace at 100 ° C. for 2 minutes. A skin layer was formed on the surface of the release paper [Step (A)].

To 100 parts of Crisbon (registered trademark) TK1015T (manufactured by DIC Corporation, polyurethane), 20 parts of dimethylformamide (DMF) was added and stirred to adjust the viscosity to 25,000 mPa · s. 30 parts of Peco Flame STC powder (trade name, manufactured by Arkroma, flame retardant), Neocerbon (registered trademark) N # 1000M (manufactured by Eiwa Kasei Co., Ltd., chemical foaming agent, OBSH) with respect to the obtained polyurethane dilution 1 part of SH193 (trade name, manufactured by Toray Dow Corning Co., Ltd., foam stabilizer) and 8 parts of Lalomin (registered trademark) C260 (Enomoto Kasei Co., Ltd., crosslinking agent) were added to obtain a polyurethane-containing composition.
The obtained polyurethane-containing composition was mechanically foamed by stirring for 20 minutes with a planetary mixer at a frequency of 20 Hz, and a specific gravity of 0.7 g / cm ³ mixed with bubbles having an average cell diameter of 60 μm to 120 μm and a viscosity of 30,000. Cushion layer forming composition 1 which is an mPa · s foamed paint was obtained [step (B)].
The obtained cushion layer forming composition 1 was applied onto the surface of the skin layer formed on the surface of the release paper described above at a coating amount of 250 g / m ² to form a cushion layer forming composition layer. [Step (C)].
Before drying the cushion layer-forming composition layer, the wet-laminated surface of the brush interlock knitted fabric (double-sided knitted fabric having a raised surface on one side) is bonded to the base fabric, and then 170 ° C. And dried in a drying oven for 2 minutes. By heating and drying, the cushion layer is cured, the pores derived from mechanical foaming contained in the cushion layer are fixed, and the pores are formed by foaming of the chemical foaming agent contained in the cushion layer forming composition. Synthetic leather of Example 1 having a cushion layer 14 and a skin layer 18 having two or more kinds of pores having different cross-sectional shapes, which are pores derived from a chemical foaming agent and pores derived from mechanical foaming, on the surface of the cloth 12 [Step (D)] was obtained.
In addition, the cross-sectional shape of the holes in the cushion layer is observed by the above-described method, and the shape is different from each other: a circular hole having a circular cross-sectional shape, a hole having an elliptical cross-sectional shape, and a hole having an indefinite cross-sectional shape. It was confirmed to have three types of holes.

[Example 2]
In the same manner as in the synthetic leather manufacturing method of Example 1, the cushion layer forming composition was applied to the skin layer to form a cushion layer forming composition layer, and heated in a drying furnace at 170 ° C. for 2 minutes. A cushion layer was formed on the skin layer.
Thereafter, 60 parts of DMF, Bernock DN950 (trade name, crosslinking agent) and Accel T81E (trade name, accelerator) are added to 100 parts of Crisbon TA205FT (manufactured by DIC, adhesive) on the surface of the formed cushion layer. An adhesive layer forming composition 1 obtained by adding a specified amount and stirring was applied at 100 g / m ^{2 and} heated in a drying furnace at 130 ° C. for 1 minute to form an adhesive layer forming composition layer. . On the surface of the obtained adhesive layer forming composition layer, a surface having brushed interlocked knitted fabric, which is a base fabric, is bonded by a dry laminating method and cured in an atmosphere at 40 ° C. for 48 hours. A synthetic leather of Example 2 having a cushion layer, an adhesive layer, and a skin layer in this order on the fabric was obtained.
When the cross section of the synthetic leather of Example 2 was observed, it was confirmed that the cushion layer had two or more types of pores having different shapes from each other as in Example 1.

[Comparative Example 1]
100 parts of Rezamin CUS-1500 (trade name, manufactured by Dainichi Seika Kogyo Co., Ltd., polyurethane), 270 parts of DMF, 25 parts of B1403 (trade name, manufactured by Nippon Light Metal Co., Ltd., flame retardant), and Crisbon SD-7 ( 3 parts of a product name (manufactured by DIC Co., Ltd., film-forming auxiliary) was added to prepare wet paint 1. The obtained wet paint was applied to a 1000 g / m ² brush interlock knitted fabric to prepare a wet base 1.
Thereafter, 100 g / m ^{2 of} the adhesive layer forming composition 1 obtained in Example 2 was applied on the surface of the skin layer formed in the mold release market in the same manner as in Example 1, and a drying furnace at 130 ° C. After heating for 1 minute, the composition layer for forming an adhesive layer and the wet base 1 are bonded together by a dry laminating method and cured at 40 ° C. for 48 hours. 1-derived layer], a synthetic leather of Comparative Example 1 having an adhesive layer and a skin layer in this order was obtained.
When the cross section of the synthetic leather of Comparative Example 1 was observed, it was confirmed that the cushion layer was a continuous porous layer having vertically long continuous pores having similar shapes to each other.

[Comparative Example 2]
12 parts of dimethylformamide (DMF), 40 parts of ethyl acetate, 30 parts of Peco Flame STC powder (trade name, manufactured by Arkroma, Inc., flame retardant) with respect to 100 parts of Crisbon TK1015T (manufactured by DIC Corporation, polyurethane) 4 parts of Microsphere FN-100M (trade name, manufactured by Matsumoto Yushi Co., Ltd., microcapsule foaming agent: chemical foaming agent) and 8 parts of Lalomin C260 (Enomoto Kasei Co., Ltd., cross-linking agent) are added to form a cushion layer. Composition 2 was obtained.
The obtained composition 2 for forming a cushion layer was coated with 150 g / m ² on the surface of the skin layer formed on the release paper obtained in Example 1, and then dried for 2 minutes in a 170 ° C. drying oven. The cushion layer 2 was formed by heating.
On the surface of the cushion layer 2 formed, 100 g / m ^{2 of} the adhesive layer forming composition 1 obtained in Example 2 was applied and heated in a drying furnace at 130 ° C. for 1 minute, and then a dry lamination method. In the brush interlock knitted base fabric as the base fabric, the raised surface and the adhesive layer forming composition layer were bonded together and cured at 40 ° C. for 48 hours to obtain the synthetic leather of Comparative Example 2. Obtained.
When the cross section of the synthetic leather of Comparative Example 1 was observed, it was confirmed that the cushion layer had only circular holes whose cross-sectional shape derived from microsphere FN-100M, which is a chemical foaming agent.

(Evaluation of the synthetic leather obtained)
The following items were evaluated for the synthetic leather of Examples and Comparative Examples. The results are shown in Table 1 below.
1. Number of steps The number of steps required for production is described. The smaller the number of steps, the better the productivity.
2. Curing The presence / absence of curing time required for curing the adhesive layer was described.

3. Bending softness Based on the skin softness test method of JIS K 6542 (1974), the bending resistance of the synthetic leather was measured by the Gurley method or the slide method. The smaller the value of the bending resistance, the more flexible it is.

4). Texture The texture of synthetic leather (50 cm × 50 cm), that is, the smoothness of the surface tactile sensation, the flexibility when bent, etc. were evaluated by 10 monitors and judged according to the following criteria.
(Standard)
Good: 8 or more out of 10 monitors evaluated as good.
Slightly good: 5 to 7 people in the monitor evaluated it as good.
Slightly poor: 1 to 4 people in the monitor evaluated as good.
Poor: 0 in the monitor evaluated as good (nothing evaluated as good).

5. Wrinkle returnability Synthetic leather (50 cm × 50 cm) was folded in half with the skin layer on the inside, and a 1 kg load was applied and left for 30 minutes.
Thereafter, the load was removed, the synthetic leather was expanded, and immediately after that, it was visually observed, and the returnability of the folded wrinkles was evaluated according to the following criteria.
(Standard)
A: Folding wrinkles could hardly be confirmed by visual observation.
B: Although slight wrinkles were confirmed by visual observation, the wrinkles disappeared with the steam iron.
C: Folding wrinkles observed visually remained without disappearing.

6). Comprehensive evaluation A: A soft texture and a wrinkle return property are favorable, and it is practical.
B: Soft texture and wrinkle returnability are good and suitable for practical use, but productivity is low.
C: Since the texture is poor and the impact resilience is small, it is not suitable for practical use.
In the above evaluation criteria, the evaluations A to B are levels that have no practical problem.

As is apparent from Table 1, the synthetic leathers of Example 1 and Example 2 had the same bending resistance as the skin material of the comparative example, and had better texture and wrinkle return properties.
In addition, the number of processes was small and the productivity was good. In particular, in the production of the synthetic leather of Example 1 having no adhesive layer, it can be seen that the synthetic leather can be produced with higher productivity because no curing time is required.
On the other hand, the synthetic leather of Comparative Example 1 had a low wrinkle reversibility compared to the Examples, and the wrinkles did not return naturally. Moreover, it turns out that there are many manufacturing processes and productivity is lower than the synthetic leather of an Example. Further, the synthetic leather of Comparative Example 2 was at a practically problematic level in both flexibility and wrinkle returnability.

10, 20 Synthetic leather 12 Base material (base fabric)
14 Cushion layer 16A Hole having a circular cross section (hole derived from chemical foaming agent)
16B Holes with an elliptical cross section (holes derived from mechanical foaming)
17 Hole with an indefinite cross section 18 Skin layer

Claims (7)

A base fabric having raised or pile yarn on at least one surface, and provided with a cushion layer and an outer skin layer in this order on the surface having the raised or pile yarn,
The cushion layer includes polyurethane, and the polyurethane has two kinds of cross-sectional shapes different from each other selected from a hole having a circular cross-sectional shape, a hole having an elliptical cross-sectional shape, and a hole having an indefinite cross-sectional shape. Synthetic leather with the above holes.   The synthetic leather according to claim 1, wherein the pores of the cushion layer include pores having a circular cross-sectional shape derived from a chemical foaming agent and pores having an elliptical cross-sectional shape derived from mechanical foaming.   The synthetic leather according to claim 1 or 2, wherein the cushion layer includes pores having an indefinite cross-sectional shape in which two or more pores are connected.   The polyurethane in the cushion layer includes at least one solvent-based polyurethane selected from the group consisting of polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof. 1. Synthetic leather according to item 1. A step of applying a skin layer forming composition to the release material surface and drying to form a skin layer;
A polyurethane-containing composition containing a polyurethane, a chemical foaming agent and a solvent and having a viscosity of 10,000 mPa · s to 80,000 mPa · s is prepared, and the resulting polyurethane-containing composition is stirred to remove bubbles formed by stirring. Preparing an underlying cushion layer forming composition;
Applying the obtained composition for forming a cushion layer to a surface of the skin layer that does not have a release material, and forming a cushion layer forming composition layer on the skin layer;
The cushion layer-forming composition layer and the surface of the base fabric having raised or pile yarn on at least one surface are brought into close contact with each other and heated and dried to foam the chemical foaming agent. And a step of forming a cushion layer having two or more types of pores having different shapes from each other.   The cushion layer forming composition is further at least one selected from the group consisting of alkylsulfosuccinate, alkylsulfate, alkylsulfonate, higher fatty acid ester, ether-modified silicone compound, and dimethylpolysiloxane. The manufacturing method of the synthetic leather of Claim 5 containing the foam stabilizer of this.   The step of forming the cushion layer includes forming a hole having a circular cross-sectional shape derived from a chemical foaming agent in the cushion layer, and curing the cushion layer to stir the cushion layer forming composition. The method for producing a synthetic leather according to claim 5, further comprising: fixing a hole having an elliptical cross-sectional shape formed by mechanical foaming.