JP6145280B2 - Manufacturing method of genuine leather products - Google Patents

Description

  The present invention relates to a method for manufacturing a genuine leather product.

  Genuine leather has a distinctive texture (so-called “leather-likeness”) such as appearance (gloss, squeeze, etc.), texture (flexibility, elasticity, swelling, etc.), touch (smoothness of the surface, etc.) and a sense of quality. It is used in various fields such as bags, shoes, interior materials, and vehicle interior materials. Genuine leather is usually finished by painting the surface, and a coating film (resin film) called a base coat layer, a color coat layer, and a top coat layer is laminated on the genuine leather. In the present specification, genuine leather before painting is referred to as “genuine leather base material”, and genuine leather after painting is referred to as “genuine leather product” for distinction for convenience.

Here, the base coat layer is to cover the silver surface on the surface of the genuine leather substrate, thereby concealing defects such as worms, scratches, and skin scars, and stably forming a coating film on the top. Is a coating film provided mainly for the purpose. Furthermore, there is also a role of assisting the color coat layer by coloring.
The color coat layer is a coating film of an intermediate layer provided mainly for the purpose of imparting a desired color to a genuine leather product by coloring itself. Furthermore, there is also a role of concealing the defects of the leather base material that cannot be concealed by the base coat layer.
The top coat layer is a coating film of the uppermost layer (outermost layer) provided mainly for the purpose of adjusting the texture, touch, gloss, color, and the like and improving physical properties such as wear resistance.

  Since this leather base material is a natural product, its surface has scratches and the surface may not be uniform. In order to conceal these, a method of concealing the scratches by applying a resin and then buffing the surface of the genuine leather base material to form a base coat layer before the base coat layer is formed is employed. However, at this time, a large portion and a small portion are generated in the amount of the resin left on the surface of the genuine leather base material, and there is a problem that color unevenness occurs due to permeation variation of the paint forming the base coat layer.

  In order to cope with such a problem, for example, a method such as thick coating of the resin in the resin coating performed before forming the base coat layer or a resin coating after the buffing process can be considered, In the case of these methods, although the uneven color due to the permeation variation of the paint forming the base coat layer is reduced, there is a problem that the texture of the obtained leather becomes coarse.

  An object of the present invention is to provide a method for producing a genuine leather product capable of preventing color unevenness due to permeation variation of a paint forming a base coat layer without impairing the original texture and feel of the genuine leather.

The present invention is a method for producing a genuine leather product in which a base coat layer, a color coat layer, and a top coat layer, all of which are mainly made of a polyurethane resin, are sequentially laminated on a genuine leather base material. Is formed by applying the second coating, and the second coating is applied wet-on-wet before the first coating is dried.
Further, the thickness of the base coat layer is 30 to 45 μm, the layer thickness by the first application of the base coat layer is 24 to 36 μm, and the layer thickness by the second application of the base coat layer is 6 to 9 μm. It is preferable.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the genuine leather product which can prevent the color nonuniformity by the osmosis | permeation variation of the coating material which forms a basecoat layer can be provided, without impairing the original texture and touch of genuine leather.

Hereinafter, embodiments of the present invention will be described in detail.
The genuine leather product to which the present invention is directed is obtained by laminating a base coat layer, a color coat layer, and a top coat layer mainly composed of a polyurethane resin in this order on a genuine leather base material.

  The leather base material used in the present invention is not particularly limited, and examples of raw materials include mammals such as cattle, horses, pigs, goats, sheep, deer, kangaroos, birds such as ostriches, sea turtles, monitor lizards, and pythons. And those derived from reptiles such as crocodiles. Especially, what uses a cowhide with a high versatility and a large area as a raw material is preferable. Raw hides or those that have been salted to prevent decay are called raw hides, and those in this state are used in the leather making process.

  The leather (raw leather) is used to impart durability (heat resistance, rot resistance, chemical resistance, etc.), and the leather-like material is called “leather” (simply called “leather”). It is distinguished from “skin” which is called and not hesitated.

The leather making process is roughly divided into a tanning process, a dyeing process, and a finishing process, and is further divided into the following.
Moistening process: Raw leather, soaking / back splitting, lining, hair removal / lime pickling, splitting, remineralization, decalcification / fermentation, soaking, tanning dyeing process;・ Greasing, setting out, drying, taste-removing, staking (squeezing, tapping), tension drying, silver peeling Finishing process: painting, ironing / embossing, polishing

  Although the individual steps are being improved, it can be said that the steps are technically determined and are well known in the art. However, the order may be partially changed, omitted, or replaced with another process.

  Prior to painting, usually silvered. Silver peeling is a process for smoothing the surface by scraping the surface of the silver surface, removing elements that affect the appearance quality such as individual differences, site differences, worms, scratches, and skin scars, and making them uniform. It is. Usually, it is stripped with silver, but it may not be stripped for the purpose of taking advantage of the original design of animal skins.

  After the peeling of the silver, the base coat layer mainly composed of polyurethane resin is formed as the first coating film by coating the surface (silver side) of the genuine leather substrate. As described above, the role of the base coat layer is to conceal the defects and stabilize the formation of the upper coating film.

  The base coat layer of the present invention is formed by applying a base coat layer-forming coating material and heat treatment. At this time, it is important to form the base coat layer by applying twice wet-on-wet. This is because if a sufficient concealing effect is obtained by a single application, the amount of application increases and the texture becomes coarse. This is because, when the coating is applied twice, the penetration is suppressed, so that a concealing effect can be obtained even with a small coating amount and there is no influence on the texture. That is, in the first application, the leather penetrates into the leather by concealing scratches and the like while improving adhesion, and the second coating is applied on the coating film by the first application. Since a uniform thin film can be formed without any deterioration, a concealing effect is further imparted while preventing deterioration of the texture. Here, “wet-on-wet” means that the coating material applied for the first time is applied before the drying, that is, when the coating material is wet, the second time. By applying wet-on-wet, repellency due to the surface tension of the base coat layer forming paint can be suppressed during the second application, so a more uniform and flat base coat layer can be formed. This makes it difficult for the coating material to permeate through, and improves the color unevenness and tactile sensation (surface roughness) of the resulting leather product.

  The preferable range of the thickness of the base coat layer after drying is 24-36 μm for the first time and 6-9 μm for the second time. By setting the thickness of the first time and the second time in the above-described range, it is possible to improve the color unevenness of the obtained leather product without impairing the texture.

  The thickness of the entire base coat layer is preferably 30 to 45 μm. When the thickness is less than 30 μm, the defects of the leather base material cannot be sufficiently concealed, color unevenness occurs on the surface of the leather product, and physical properties such as wear resistance and bending resistance are deteriorated. There is a risk of doing. If the thickness exceeds 45 μm, the texture and feel may be impaired, or the leather-specific appearance may be impaired.

  In order to apply the base coat layer-forming coating material, for example, a reverse roll coater, spray coater, roll coater, gravure coater, kiss roll coater, knife coater, comma coater and the like can be used without particular limitation. Among these, for the first application, application with a reverse roll coater is preferable from the viewpoint of adhesion between the leather and the base coat layer and concealment of scratches. In the second application, application by a spray coater is preferable because a uniform coating film can be formed with a small application amount without penetrating the leather.

The wet coating amount may be set as appropriate according to the desired thickness of the base coat layer. Preferably, the first wet application amount is 80 to 120 g / m ² , and the second wet application amount is 20 to 30 g / m ² . By setting the thickness of the first time and the second time in the above-described range, it is possible to improve the color unevenness of the obtained leather product without impairing the texture.

As the polyurethane resin used for the base coat layer forming coating material, a one-component resin capable of forming a film only by removing the solvent by drying is used.
The one-component resin is usually marketed in the form of emulsified dispersion in water (emulsion type) or dissolved in an organic solvent, but the emulsion type is preferably used from the viewpoint of environmental burden.

  Examples of the polyurethane resin include a polycarbonate-based polyurethane resin, a polyether-based polyurethane resin, and a polyester-based polyurethane resin. These can be used alone or in combination of two or more. Of these, a polycarbonate-based polyurethane resin is preferable from the viewpoint of durability, and a polyether-based polyurethane resin is preferable from the viewpoint of texture and feel, and these are more preferably used in combination.

  The base coat layer is mainly composed of a polyurethane resin and does not necessarily require other resin components, but may contain them. Examples of the resin component other than the polyurethane resin include an acrylic resin, an epoxy resin, and a silicone resin. Especially, it is preferable to use it combining an acrylic resin from a viewpoint of texture and touch.

  The acrylic resin is not particularly limited. For example, acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate; methacrylic acid Alkyl methacrylates such as methyl, ethyl acrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy acrylate Hydroxy group-containing acrylic esters such as butyl; heavy hydroxy group-containing methacrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, etc. Mention may be made of the body. These can be used alone or in combination of two or more.

  A commercially available acrylic resin can be used, and an emulsion type is preferably used from the viewpoint of environmental load.

  It is preferable that the usage-amount of an acrylic resin is 60 weight% (solid content) or less with respect to a polyurethane resin. If the amount used exceeds 60% by weight, the wear resistance may be impaired.

  The coating for forming the base coat layer is, as necessary, a crosslinking agent, a colorant (pigment, dye), a matting agent, a smoothing agent, a surfactant, a filler, and a leveling agent as long as the physical properties of the base coat layer are not impaired. In addition, various additives such as a thickener may be included.

The color of the base coat layer is colored as desired, that is, the same color as the color coat layer or an approximate color as necessary. This facilitates toning by the color coat layer.
If the structure of this invention is taken, the color nonuniformity of a basecoat layer will become small and a color difference ((DELTA) E ^* ) will be 0.2 or less. As a result, ΔE ^* of the uneven color of the genuine leather product is 0.2 or less. For color difference, brightness and saturation are measured in L ^* , a ^* , b ^* display units using a spectroscopic colorimeter CM-1000 manufactured by Minolta Camera Co., Ltd. The five color differences are measured, and the average is calculated.

  The heat treatment after applying the paint for forming the base coat layer is performed in order to evaporate the solvent in the paint, dry the resin, promote the crosslinking reaction as necessary, and form a coating film having sufficient strength. Is called. In order to prevent excessive moisture evaporation of the leather base material, the heat treatment is preferably performed so that the temperature of the leather base material itself does not exceed 80 ° C. Therefore, it is preferable that the heat processing temperature is 90-130 degreeC, More preferably, it is 100-120 degreeC. The heat treatment time is preferably 1 to 5 minutes, more preferably 2 to 3 minutes. If the heat treatment temperature or heat treatment time is less than the lower limit, drying or crosslinking may be insufficient. If the heat treatment temperature or the heat treatment time exceeds the upper limit value, the texture and feel may be impaired.

  Thus, a base coat layer can be formed.

  Next, the surface of the base coat layer is further coated to form a color coat layer mainly composed of polyurethane resin as the second coating film. As described above, the role of the color coat layer is to color the genuine leather product.

The color coat layer of the present invention is formed by applying a color coat layer-forming coating material and heat treatment.
In order to apply the coating material for forming the color coat layer, for example, a reverse roll coater, a spray coater, a roll coater, a gravure coater, a kiss roll coater, a knife coater, a comma coater and the like can be used without particular limitation. Especially, it is preferable to apply | coat with a spray coater from a viewpoint that a uniform coating film can be formed.

  Examples of the polyurethane resin used for the color coat layer-forming coating material include the same polyurethane resin as in the case of the base coat layer. Moreover, the resin component other than a polyurethane resin may be included.

For coloring the color coat layer, pigments such as organic pigments and inorganic pigments are used.
The amount of the colorant to be used is not particularly limited and may be appropriately set according to a desired color, but is 25% by weight or less in terms of solid content with respect to the entire composition including the additive. It is preferably 15 to 23% by weight. If the amount used exceeds 25% by weight, the texture and feel may be impaired, or the coating film strength may be reduced and physical properties such as wear resistance may be deteriorated.

  The paint for forming the color coat layer may contain various additives as in the case of the base coat layer.

The thickness of the color coat layer is preferably 3 to 15 μm, more preferably 6 to 9 μm. If the thickness is less than 3 μm, it is difficult to form a uniform coating film, and color spots may occur, and physical properties such as wear resistance and flex resistance may be deteriorated. If the thickness exceeds 15 μm, the texture and feel may be impaired, or the leather-specific appearance may be impaired.
The wet coating amount may be appropriately set according to the desired thickness of the color coat layer.
Thus, a color coat layer can be formed.

  Next, a top coat layer mainly composed of a polyurethane resin is formed as the third coating film by further painting the surface of the color coat layer. The role of the top coat layer is to adjust the texture, touch, gloss, color, and the like, and improve physical properties such as wear resistance.

The topcoat layer of the present invention is formed by applying a topcoat layer-forming coating material and heat treatment.
In order to apply the coating for forming the topcoat layer, for example, a reverse roll coater, spray coater, roll coater, gravure coater, kiss roll coater, knife coater, comma coater and the like can be used without particular limitation. Especially, it is preferable to apply | coat with a spray coater from a viewpoint that a uniform coating film can be formed.

  Examples of the polyurethane resin used in the coating material for forming the topcoat layer include the same polyurethane resin as in the case of the basecoat layer. Moreover, the resin component other than a polyurethane resin may be included.

  The topcoat layer-forming coating material may contain various additives as in the case of the basecoat layer.

  It is not always necessary to crosslink the resin constituting the topcoat layer, but it is preferable that the resin is crosslinked by using a crosslinking agent or a self-crosslinking resin. Thereby, physical properties such as wear resistance can be improved. As the crosslinking agent, an isocyanate-based crosslinking agent can be used.

  It is preferable that the usage-amount of an isocyanate type crosslinking agent is 15-25 weight% in conversion of solid content with respect to the whole composition containing an additive, More preferably, it is 17-23 weight%. If the amount used is less than 15% by weight, physical properties such as wear resistance may be deteriorated. If the amount used exceeds 25% by weight, the texture and feel may be impaired.

Although it is not always necessary to color the topcoat layer, it is preferable that the topcoat layer is colored in the same color of the color coat layer by a colorant from the viewpoint of reducing uneven color. Examples of the colorant used include the same pigments as in the color coat layer.
It is preferable that the usage-amount of a coloring agent is 1 to 7 weight% or less in conversion of solid content with respect to the whole composition containing an additive, More preferably, it is 3 to 5 weight%. If the amount used is less than 1% by weight, the yellowing concealment effect may not be sufficiently exhibited. If the amount used exceeds 7% by weight, the texture and feel may be impaired, the coating film strength may be reduced and physical properties such as wear resistance may be deteriorated, and the colorant may be transferred.

  The thickness of the top coat layer is preferably 3 to 17 μm, more preferably 6 to 14 μm. If the thickness is less than 3 μm, physical properties such as wear resistance may be deteriorated. If the thickness exceeds 17 μm, the texture and feel may be impaired.

  Thus, a top coat layer can be formed.

  The genuine leather product targeted by the present invention comprises a genuine leather substrate, a base coat layer, a color coat layer, and a top coat layer as essential constituent members. One or two or more coating films may be provided between the films.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. In the examples, “%” and “parts” are based on weight.
The evaluation was according to the following method.

[Color unevenness]
Using a spectroscopic colorimeter CM-1000 manufactured by Minolta Camera Co., Ltd., the lightness and saturation of the obtained genuine leather product specimens were measured in L ^* a ^* b ^* display units. The color difference was measured at 5 points, the average was calculated, and evaluated according to the following criteria.
○: Color difference (ΔE ^* ) is less than 0.2 Δ: Color difference (ΔE ^* ) is 0.2 or more and less than 0.3 ×: Color difference (ΔE ^* ) is 0.3 or more

[Texture (BLC value)]
One test piece having a size of 150 mm square was sampled, and a strain measurement value (BLC value) was measured when the test piece was pushed in with a load of 500 g using ST300 Laser Softness Tester (manufactured by BLC Laser Technology Center Ltd.).
A larger strain measurement value indicates a softer texture.
○: Strain measurement value is 3.0 mm or more Δ: Strain measurement value is 2.0 mm or more and less than 3.0 mm ×: Strain measurement value is less than 2.0 mm

[Texture (sensory evaluation)]
An inspector touched the test piece to evaluate hand feeling (feeling when holding or holding the test piece) and judged according to the following criteria.
A: A soft texture unique to genuine leather.
Δ: Slightly hard texture.
X: The texture was hard and the texture peculiar to genuine leather was impaired.

[Feel]
An inspector touched the surface of the test piece to perform sensory evaluation, and judged according to the following criteria.
○: The surface was smooth and did not feel rough.
Δ: A slight roughness was felt on the surface.
X: Feeling rough on the surface.

[Example 1]
(1) Preparation of Genuine Leather Base Adult cowhide was used as the raw leather, and silvering was performed through a normal process. The dyeing was performed so as to have the same color as the base coat layer.

(2) Formation of base coat layer [Prescription A1]
1) Product name “BAYDERM Bottom DLV”; 160 parts (polycarbonate polyurethane resin, solid content 40%)
2) Product name “BAYDERM Bottom 51UD”; 200 parts (polyether polyurethane resin, solid content 35%)
3) Product name "PRIMAL SB-300"; 200 parts (acrylic resin, solid content 34%)
4) Trade name “EUDERM White CB-N”; 112.4 parts (pigment, solid content 60%)
5) Trade name “EUDERM Caramel C—N”; 3.1 parts (pigment, 35% solids)
6) Trade name “EUDERM Bordo CB-N”; 2.7 parts (pigment, solid content 40%)
7) Product name “EUDERM Black B-N”; 1.8 copies
(Pigment, solid content 23%)
8) Trade name “EUDERM Nappa Softs”; 110 parts (matting agent, solid content 25%)
9) Product name “EUDERM Matching Agent SN-C”; 120 parts (matting agent / filler, solid content 23%)
10) Trade name “EUDERM Paste DO”; 40 parts (matting agent / filler, solid content 52%)
11) Trade name “AQUADERM Fluid H”; 10 parts (leveling agent, solid content 100%)
12) Trade name “AQUADERM XL-50”; 150 parts (crosslinking agent, hexamethylene diisocyanate (HDI), solid content 50%)
13) Trade name “ACRYSOL RM-1020”; about 10 parts (thickener, solid content 20%)
14) Water; 150 parts

  All raw materials except LAN are made by LANXESS.

According to prescription A1, each raw material was mixed with the mixer, and the coating material 1 for basecoat layer formation was prepared. At this time, using a cup viscometer (manufactured by Anest Iwata Co., Ltd.), the viscosity was adjusted with a thickener so as to be 50 seconds.
The total number of parts of the paint is 1270 parts, of which 434.9 parts, or 34.2%, is the total solid content. The ratio of acrylic resin to urethane resin was 50.7%.

Using the reverse roll coater (trade name “JUMBOSTAR-SR”, manufactured by Ge.Ma.Ta.SpA) on the surface of the genuine leather substrate obtained in (1), the base coat layer-forming coating material 1 is wet-coated. It apply | coated so that the quantity might be set to 100 g / m < ² >. The thickness at the time of drying was 32 μm when converted from the solid content and the coating amount.

Subsequently, according to the following prescription A2, each raw material was mixed with the mixer, and the base coat layer forming coating material 2 was prepared. At this time, using a cup viscometer (manufactured by Anest Iwata Co., Ltd.), the viscosity was adjusted with a thickener so as to be 25 seconds.
The total number of parts of the paint was 1265 parts, of which 433.9 parts, or 34.3%, was the total solid content, and the ratio of the acrylic resin to the urethane resin was 50.9%.
[Prescription A2]
1) Product name “BAYDERM Bottom DLV”; 160 parts (polycarbonate polyurethane resin, solid content 40%)
2) Product name “BAYDERM Bottom 51UD”; 200 parts (polyether polyurethane resin, solid content 35%)
3) Product name "PRIMAL SB-300"; 200 parts (acrylic resin, solid content 34%)
4) Trade name “EUDERM White CB-N”; 112.4 parts (pigment, solid content 60%)
5) Trade name “EUDERM Caramel C—N”; 3.1 parts (pigment, 35% solids)
6) Trade name “EUDERM Bordo CB-N”; 2.7 parts (pigment, solid content 40%)
7) Trade name “EUDERM Black B-N”; 1.8 parts (pigment, solid content 23%)
8) Trade name “EUDERM Nappa Softs”; 110 parts (matting agent, solid content 25%)
9) Product name “EUDERM Matching Agent SN-C”; 120 parts (matting agent / filler, solid content 23%)
10) Trade name “EUDERM Paste DO”; 40 parts (matting agent / filler, solid content 52%)
11) Trade name “AQUADERM Fluid H”; 10 parts (leveling agent, solid content 100%)
12) Trade name “AQUADERM XL-50”; 150 parts (crosslinking agent, hexamethylene diisocyanate (HDI), solid content 50%)
13) Trade name “ACRYSOL RM-1020”; about 5 parts (thickener, solid content 20%)
14) Water; 150 parts

  All raw materials except LAN are made by LANXESS.

Using a spray coater (trade name “TU ROT.3400 / 1.41”, manufactured by BARNINI Srl), the base coat layer forming paint 2 is applied to the wet coated surface after the base coat layer forming paint 1 is applied. The wet coating amount was 20 g / m ^{2, and} it was left in a drier adjusted to 110 ° C. for 3 minutes for heat treatment. The thickness at the time of drying was 7 μm when converted from the solid content and the coating amount. The thickness of the entire base coat layer was 39 μm, and the color unevenness (color difference) was 0.20.

(3) Embossing and staking
For the intermediate product obtained in (2), using an embossing machine (trade name “KOMBIPRESS-1800NE”, manufactured by BERGI ofb spa), roll temperature 90 ° C., pressure 150 kgf / m ² , processing speed 5 m The stamping pattern was given by embossing under the conditions of / min.
Next, using a milling machine (trade name “N2500 × 1200TS”, manufactured by BAGGIO Technology sl.l), the kneading process was performed for 30 minutes under the conditions of a temperature of 20 ° C. and a rotation speed of 15 rpm.
Next, using a staking machine (trade name “3H3200A”, manufactured by CARTIGLIANO SpA), the punching was performed under the conditions of a processing speed of 8 m / min and a driving depth of 2 mm, 1.5 mm, and 1 mm in order. .

(4) Formation of color coat layer [Prescription B1]
1) Product name “BAYDERM Bottom DLV”; 160 parts (polycarbonate polyurethane resin, solid content 40%)
2) Product name “BAYDERM Bottom 51UD”; 200 parts (polyether polyurethane resin, solid content 35%)
3) Product name "PRIMAL SB-300"; 200 parts (acrylic resin, solid content 34%)
4) Trade name “EUDERM White CB-N”; 112.4 parts (pigment, solid content 60%)
5) Trade name “EUDERM Caramel C—N”; 3.1 parts (pigment, 35% solids)
6) Trade name “EUDERM Bordo CB-N”; 2.7 parts (pigment, solid content 40%)
7) Trade name “EUDERM Black B-N”; 1.8 parts (pigment, solid content 23%)
8) Trade name “EUDERM Nappa Softs”; 110 parts (matting agent, solid content 25%)
9) Product name “EUDERM Matching Agent SN-C”; 120 parts (matting agent / filler, solid content 23%)
10) Trade name “EUDERM Paste DO”; 40 parts (matting agent / filler, solid content 52%)
11) Trade name “AQUADERM Fluid H”; 5 parts (leveling agent, solid content 100%)
12) Trade name “ACRYSOL RM-1020”; about 5 parts (thickener, solid content 20%)
13) Water; 150 parts

  All raw materials except LAN are made by LANXESS.

According to prescription B1, each raw material was mixed with a mixer to prepare a paint for forming a color coat layer. At this time, using a cup viscometer (manufactured by Anest Iwata Co., Ltd.), the viscosity was adjusted with a thickener so as to be 25 seconds.
The total number of parts of the paint was 1115 parts, of which 358.9 parts, or 32.2%, was the total solid content, and the pigment content was 19.5%.

Using a spray coater (trade name “TU ROT.3400 / 1.41”, manufactured by BARNINI Srl) on the surface of the intermediate product that has undergone step (3), a coating amount for forming a color coat layer is 25 g. / M ^2, and heat-treated by leaving in a dryer adjusted to 110 ° C. for 3 minutes.
The thickness of the color coat layer at the time of drying was 7.0 μm when converted from the solid content and the coating amount.

(5) Formation of topcoat layer [prescription C1]
1) Product name “HYDRHOLAC UD-2”; 320 parts (polycarbonate polyurethane resin, solid content 25%)
2) Product name “HYDRHOLAC Finish HW-2”; 140 parts (polycarbonate polyurethane resin, solid content 35%)
3) Product name “AQUADERM Finish HAT”; 200 parts (polycarbonate polyurethane resin, solid content 40%)
4) Trade name “EUDERM White CB-N”; 22.4 parts (pigment, solid content 60%)
5) Trade name “EUDERM Caramel C—N”; 3.1 parts (pigment, 35% solids)
6) Trade name “EUDERM Bordo CB-N”; 2.7 parts (pigment, solid content 40%)
7) Trade name “EUDERM Black B-N”; 1.8 parts (pigment, solid content 23%)
8) Product name “Rosilk 2229”; 70 parts (smoothing agent, solid content 60%)
9) Trade name “AQUADERM Additive SF”; 30 parts (smoothing agent, solid content 50%)
10) Product name “AQUADERM Fluid H”; 10 parts (leveling agent, solid content 100%)
11) Trade name “AQUADERM XL-50”; 150 parts (crosslinking agent, hexamethylene diisocyanate (HDI), solid content 50%)
12) Trade name “ACRYSOL RM1020”; about 10 parts (thickener, solid content 20%)
13) Water; 150 parts

  All raw materials except LAN are made by LANXESS.

According to prescription C1, each raw material was mixed with a mixer to prepare a topcoat layer-forming coating material. At this time, using a cup viscometer (manufactured by Anest Iwata Co., Ltd.), the viscosity was adjusted with a thickener so as to be 25 seconds.
The total number of parts of the paint was 1110 parts, of which 369.0 parts, or 33.2%, was the total solid content, and the pigment content was 4.3%.

Using a spray coater (trade name “TU ROT.3400 / 1.41”, manufactured by BARNINI Srl) on the surface of the intermediate product obtained in (4), a wet coating amount of 25 g is applied. / M ^2, and heat-treated by leaving in a dryer adjusted to 110 ° C. for 3 minutes.
The thickness of the top coat layer at the time of drying was 7.0 μm when converted from the solid content and the coating amount.

  Thus, a genuine leather product of Example 1 was obtained.

  In Example 2 and Example 3, genuine leather products were produced according to Tables 1 to 3 in the same manner as in Example 1 except that the coating amount of the first coating of the base coat layer was changed. Comparative Example 1 was carried out except that the base coat layer was not applied for the second time, and Comparative Example 2 was carried out except that the drying process (standing for 3 minutes in a dryer adjusted to 110 ° C.) was performed after the first base coat application. Genuine leather products were produced according to Tables 1 to 3 in the same manner as in Example 1.

Evaluation of genuine leather products produced according to the examples and comparative examples was made by the method described above, and the results are shown in Table 3.
As shown in Table 3, the genuine leather products of the examples were excellent in all aspects of uneven color, texture, and touch.
On the other hand, the genuine leather product of the comparative example was inferior in color unevenness, texture and touch.

Claims (2)

A method of manufacturing a genuine leather product in which a base coat layer, a color coat layer, and a top coat layer mainly comprising a polyurethane resin are sequentially laminated on a genuine leather base material, and the base coat layer is coated twice with a paint. A method for manufacturing a genuine leather product, characterized in that the second coating material is applied wet-on-wet before the first coating material is dried.   The thickness of the base coat layer is 30 to 45 μm, the layer thickness by the first application of the base coat layer is 24 to 36 μm, and the layer thickness by the second application of the base coat layer is 6 to 9 μm. The method for producing a genuine leather product according to claim 1, characterized in that: