JP2013040259A - Urethane beads topcoat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel topcoat layer having a property that can reconcile a matting effect with decreases in slimy touch and creaking sound.SOLUTION: The coating composition for forming a coated film as a topcoat of a natural leather comprises an aqueous emulsion containing 35-50 wt.% of a two-pack aliphatic polyurethane resin, 35-50 wt.% of two-pack liquid aliphatic polyurethane/acrylic resin, or 35-50 wt.% of the total of the two-pack aliphatic polyurethane resin and the two-pack aliphatic polyurethane/acrylic resin, 2-7 wt.% of silica fine particles of 0.3-30 μm particle diameter, 3-15 wt.% of polyurethane resin fine particles having plural particle diameters in the range of 6-15 μm and a Tg of -60 to -20°C, 15-35 wt.% of a crosslinking agent, 5-15 wt.% of a silicone-based tactile agent, 0-5 wt.% of a leveling agent, solid contents comprised of 0-3 wt.% of a thickening agent (total amount of the solid contents is 100 wt.%), and water.

Description

  The present invention provides a natural leather topcoat film-forming composition containing a specific amount of silica fine particles having a specific shape and polyurethane beads having a specific property, and the surface of natural leather using the natural leather topcoat film-forming composition. The present invention relates to a top coat formed by coating.

  Natural leather for automobile seats needs to be durable and comfortable to use for a long period of time, corresponding to the range of human activities ranging from low to high and low to high humidity. In addition to the material properties such as wear resistance, heat resistance, cold resistance, light resistance, antifouling properties and durability, the required properties include a so-called glaring state and unique gloss. In many cases, it is evaluated as a characteristic point related to sensibility such as giving a pleasant touch. These characteristics are given when the leather is derived from those based on the characteristics of the original leather and when the leather of the cow seat is licked to form a leather film for automobile seats. There are characteristics. The coating film on the leather surface is formed with a coating mainly made of polyurethane resin and / or acrylic resin. A polyurethane resin and / or an acrylic resin is used for forming the coating film. By adding an additive at that time, characteristics may be imparted by imparting characteristics.

It is known to use silica as an additive for such paints. In a coating formulation containing at least one surface-modified silicon dioxide coated with not only silica but also polyorganosiloxane and / or modified polyorganosiloxane, the 60 ° reflectometer value is less than 3. case, there is the invention of coating formulations having at least 140 Sears number _{M y} of (Japanese Patent Document 1 JP 2006-002151). In addition to the outstanding transparency values, the paint formulations according to the invention are evaluated for their remarkable matting effect and good scratch resistance on the paint surface. The paint formulation according to the invention is suitable for the coating of plastics used for automotive interiors. That is, the surface coated with the paint according to the present invention is preferably soft to the touch.
According to Japanese Patent Application Laid-Open No. 2007-277483 (Patent Document 2), specific examples of matting agents include polyethylene, acrylic beads, urethane beads, etc. in addition to silica-based matting agents composed of fine powder silica. Among them, it is preferable to use silica, and the blending amount is preferably 2 to 8% by weight, and 3 to 6% by weight in the coating layer. If the blending amount is less than 2% by weight, the blocking resistance of the urethane resin may be impaired, and if it exceeds 8% by weight, the leather surface feels rough ”(0037). In the present invention, the actions of a silica-based matting agent containing fine powder silica and an organic matting agent such as polyethylene, acrylic beads, and urethane beads are identified. As far as the present inventors know, both have different actions, and there are not a few differences in the action of additives. Naturally, in such a case, it is considered as a newly found characteristic.
Further, it is known that the average particle diameter of the skin material containing fine powder and having a top coat having a surface roughness Ra in the range of 0.5 to 30 μm in the standard state is 1 μm or less in the standard state. It has been. It is said that the tactile sensation performance can be improved and wear resistance can be secured by adding a fine powder or the like to the top coat (Japanese Patent Application Laid-Open No. 2006-307397).
A skin material having a base material, a silica disposed on the surface side of the base material, an aqueous polyurethane resin silica, and a polymer material-containing layer to be an aqueous polyurethane resin, wherein the surface of the polymer material-containing layer has a depth. A skin material having a minute recess of 30 to 130 μm and a ratio of the projected area of the recess of 5 to 20% based on the total projected area of the surface of the polymer material-containing layer (Patent Document 4) -302549) is also known.
As described above, many fine particles have been proposed for the fine particles to be blended in the paint, mainly resin beads such as polyurethane and polyacrylic, and fine silica particles, but various expressions are mixed.

A specific polyurethane formulation is also proposed, which contains insoluble particles in the polyurethane matrix, in which case the average diameter of the particles is described as 1 to 20 μm. However, it is not clear how much insoluble particles are present and effectively utilized in the polyurethane matrix. Notably, by using the aqueous polyurethane formulation according to the present invention, enhanced wear resistance with reduced gloss, water stability, elasticity, slight re-glossability, dark color strength It is unclear whether it contributes to having a warm and soft touch (Patent Document 5: JP-T-2005-530868, Patent Document 6: JP-A-2009-143235). In this case, it is also unclear whether only insoluble particles are effective or the combination of matrix and insoluble particles has yielded good results.
In Patent Document 5, which describes the specific use of a polyurethane resin matting agent, a favorable result is obtained by forming a top coat layer of natural leather using a polyurethane preparation comprising polyurethane containing polyurethane fine particles. Has also been revealed. Although the outline of the particle diameter of the polyurethane fine particles is shown in this, the particle diameter and the amount used when using the polyurethane fine particles are not clarified. And, it is considered that the results obtained for the polyurethane fine particles may differ depending on the particle diameter and the amount used, but the contents are not clear.

In a touch-sensitive coated body having an undercoating foam layer and an overcoating layer on a substrate, the overcoating layer is formed by applying an overcoating coating containing organic beads on the undercoating foaming layer and heating the overcoating coating to cure. The thickness is 20 to 30 μm. With urethane beads, the coefficient of dynamic friction on the surface of the overcoat layer is large, and a moist feeling and a pleasant feeling can be obtained. The size (particle size) is not particularly limited, but is preferably 5 to 50 μm, more preferably 5 to 20 μm (Patent Document 7: JP-A-2009-131818, Patent Document 8). No. 2005-297200).

JP-A-2007-314919 (Patent Document 9) discloses an aqueous polyurethane resin (A) 100 parts by mass, a polyisocyanate-based crosslinking agent (B) 40-100 parts by mass, a silicone compound (C) 5-25 parts by mass, And a surface finish for leather characterized by comprising an aqueous resin composition containing 5 to 120 parts by mass of filler (D), and with respect to 100 parts by mass of silica and aqueous polyurethane resin (A), The amount of the filler (D) is preferably in the range of 5 to 120 parts by mass, more preferably in the range of 10 to 80 parts by mass. If the blending amount of the filler is within this range, the wear resistance of the leather will be sufficient, and a soft texture of the leather can be secured (0035).
In this invention, the blending amount of the filler is only described as a whole, and neither mixing of silica and polyurethane resin fine particles in a specific amount ratio nor disclosure of the shape is disclosed.

The present inventors have completed the invention of WO2009 / 084227 (Patent Document 10).
The description of the scope of claims of the present invention is as follows.
[Claim 1] A solid content comprising 48 to 55% by weight of a two-component aliphatic polyurethane, 3 to 7% by weight of silica fine particles, 23 to 37% by weight of a crosslinking agent, and 7 to 13% by weight of a silicone-based tactile agent. 100% by weight in total) and an aqueous emulsion containing water, wherein the two-component polyurethane contains polyurethane resin fine particles in an amount of 12 to 25% by weight of the solid content. object.
[Claim 2] Solid content comprising 51 to 55% by weight of a two-part aliphatic polyurethane, 3 to 7% by weight of silica fine particles, 23 to 37% by weight of a crosslinking agent, and 7 to 13% by weight of a silicone tactile agent 100 weight% in total) and an aqueous emulsion comprising water, wherein the two-part polyurethane has a polyurethane resin fine particle matting agent in the solid content of 12 to 25 weight%, and the two-part aliphatic polyurethane acrylic emulsion. A composition for forming a natural leather coating film, comprising 6 to 10% by weight of the solid content.

These are squeaky sounds that make the top coat layer of natural leather more unpleasant in order to improve the excellent wear resistance, softness, flexibility, smooth and slimy feel. Since generation can be prevented as much as possible, it is highly appreciated.
In the present invention, it is considered effective to add a silica fine particle and to use a polyurethane resin matting agent containing a polyurethane fine particle as a combination thereof. The polyurethane resin matting agent containing polyurethane fine particles is not a polyurethane with a specific amount of polyurethane fine particles added to polyurethane, but is a polyurethane preparation containing polyurethane fine particles produced during polyurethane production. It has the characteristics obtained by the polyurethane fine particles contained therein. Since this polyurethane resin matting agent is less likely to generate squeak noise, it is effective in reducing squeak noise and effective in obtaining a slimy feeling, but on the other hand, the matte effect is small. On the other hand, the silica fine particles have a large matting effect, but the tactile sensation tends to be dry (a dry and dry feeling opposite to the slimy feeling) and also causes a squeak noise. Therefore, it is stated that it is effective to use the silica fine particles and the polyurethane resin matting agent in order to achieve both the matting effect and the reduction of the slime feel and squeak noise.

Specifically, it is unclear whether the polyurethane fine particles themselves are acting effectively or whether a polyurethane preparation comprising the entire polyurethane fine particles contained in a specific polyurethane is effective.
When using polyurethane resin fine particles and silica fine particles, it is necessary to clarify the properties of polyurethane resin fine particles, silica fine particles, and aqueous polyurethane resin, and to clarify what form is effective. Has been.

JP 2006-002151 A JP 2007-277483 A JP 2006-307397 A JP 2008-302549 A JP 2005-530868 Gazette JP 2009-143235 A JP 2009-131821 A JP-A-2005-297200 JP 2007-314919 A WO2009 / 084227

The top coat layer of natural leather for automobile seats is the outermost layer formed as a coating film on the surface of natural leather for automobile seats. The topcoat layer is a layer that comes into contact with humans, and there are few items that are directly related to the evaluation of natural leather for automobile seats, such as touch, gloss, abrasion resistance, dirt prevention, abrasion resistance, flexibility, smoothness, and sliminess. Absent. These are determined by the coating film forming the top coat layer and its additive material.
The problem to be solved by the present invention is to provide a new topcoat layer in which the characteristics of the topcoat layer satisfy both a matte effect and a slimy tactile sensation / squeak noise reduction.

Silica fine particles have a great matting effect, but the tactile sensation tends to be dry (a dry and dry feeling opposite to the feeling of slimming) and also causes squeak noise. Therefore, the present inventors can clarify that a matte effect and a slimy tactile sensation / squeak noise reduction can be achieved by using a composition containing both silica fine particles and polyurethane resin fine particles having specific properties in combination. I thought.
As a result of investigations based on this idea, (1) 35 to 50% by weight of a two-part aliphatic polyurethane resin, 35 to 50% by weight of a two-part aliphatic polyurethane / acrylic resin, or a two-part aliphatic polyurethane 35 to 50% by weight in total of resin and two-component aliphatic polyurethane / acrylic resin, 2 to 7% by weight of silica fine particles having a particle size of 0.3 to 30 μm, Tg of −60 to −20 ° C., particle size of 6 3 to 15% by weight of polyurethane resin fine particles having a plurality of particle diameters in a range of ˜15 μm, 15 to 35% by weight of a crosslinking agent, 5 to 15% by weight of a silicone-based tactile agent, 0 to 5% by weight of a leveling agent, a thickener A composition for forming a natural leather topcoat coating film comprising an aqueous emulsion containing 0 to 3% by weight of a solid content (the total of each solid component is 100% by weight) and water, and the natural leather top (2) Two-part aliphatic polyurethane resin 0 to 50% by weight, two-part aliphatic polyurethane acrylic resin 0 to 50% by weight (two-part aliphatic polyurethane) Resin and two-component aliphatic polyurethane / acrylic resin in a total of 35 to 50% by weight), 2 to 7% by weight of silica fine particles having a particle size of 0.3 to 30 μm, Tg of −60 to −20 ° C. 3-15% by weight of polyurethane resin fine particles having a particle size in the range of 6-15 μm, 15-35% by weight of crosslinking agent, 5-15% by weight of silicone-based tactile agent, 0-5% by weight of leveling agent, and increase An automobile in which a top coat is formed by coating on the surface of natural leather consisting of 0 to 3% by weight of a viscous agent (the total of each solid component is 100% by weight), and the top coat is formed on the base coat and color coat. We were able to solve the problem by the natural leather for over door.
Whether or not the above-mentioned effect can be obtained for this top coat is evaluated based on three points: tactile sensation (smoothness, squeak noise), gloss (cross, light resistance, sensory test), and physical properties (Taber abrasion, rub resistance).

The topcoat layer according to the present invention has excellent wear resistance, soft feeling, flexibility, smooth, slimy touch and a sense of unpleasantness compared to conventional topcoat layers. It is a matte topcoat layer that prevents the generation of sound as much as possible.
While the matte effect is great, the silica feels to be dry (a dry and dry feeling opposite to the feeling of slimming) and causes the occurrence of squeaking noise. The top coat layer of the present invention could be obtained by adding together polyurethane fine particles having a small matte effect to the top coat.
Furthermore, according to the present invention, it is possible to quantify and standardize the polyurethane fine particles to be added.

It is a figure which shows KES and a friction characteristic. It is a figure which shows a tactile sensation and a blotch sound.

Natural leather is a series of processes consisting of a preparation process for tanning raw leather, a tanning process using chromium or a chrome-free tanning agent, a retanning / dyeing / greasing process using a synthetic tanning agent, followed by a drying process, and a finishing process. Manufactured. The said drying process consists of a setter process, a dry drying process, a taste removal process, a vibration process, and a buffing process. The finishing process includes a backing process, a base coat layer forming process, a color coat layer forming process, a top coat layer forming process, a vibration process, and a backing process.
Although these processes are being improved with respect to individual conditions and combinations of processes, the operations performed in each process are independent and can be said to be almost fixed, and are known processes. .

The coating film that is the subject of the present invention is the top coat layer on the surface, and how to form the coating film is an important theme in terms of technology.
Since the top coat layer is formed on the base coat layer and the color coat layer, the description of the present invention will be made on the base coat layer forming step, the color coat layer forming step, and the top coat layer forming step.

(1) The base coat layer corresponds to the lowermost layer of the paint film layer, and is a layer for preparing to flatten the unevenness on the surface of the leather and stably form the layer on the upper part. In forming this layer, a composition comprising (a) a resin, (b) a pigment, an auxiliary agent, a touching agent and a leveling agent, and (c) water is applied to the surface of the leather. The ratio of resin, pigment, auxiliary agent and water to be solid content is 50 to 75: 5 to 20:10 to 30 (total 100%, weight ratio). A water-soluble two-component polyurethane resin is used. A pigment of a color to be colored is used as the pigment. Auxiliaries include surfactants, thickeners, regulators, matting agents and the like. (A) Resin, (b) Pigment, auxiliary agent, tactile sensation agent and leveling agent, and (c) water content is 20-40: 80-60 (total 100%. Weight ratio). As a coating method, brush coating, spraying, curtain coating, and roll coating are appropriately selected and used in a state containing an aqueous solution. The coating amount is 70 to 150 g / m ² , and water is evaporated by applying warm air to the surface after coating. The film thickness is 20-50 μm.
Next, embossing is performed. Embossing is a process that creates unevenness on the leather surface with a high-pressure press, and gives various patterns (textures) to the leather. Next, the leather fibers are loosened and the texture is adjusted by the blanking process and the staking process.

(2) The color coat layer is an intermediate layer of the coating film, and is a layer for causing pigments and dyes for coloring the leather to exist, and is provided on the upper part of the base coat as viewed from the leather. In forming this layer, a composition comprising (a) a resin, (b) a pigment, an auxiliary agent, a crosslinking agent, a tactile agent, and (c) water is applied to the surface of the leather. The ratio of resin (a), pigment (b), auxiliary agent (c), cross-linking agent (d), and tactile agent (e) to be solid content is 45 to 75:10 to 30: 0 to 15: 0 to 20. : 0 to 10 (total 100%, weight ratio). As the resin, a water-soluble two-component polyurethane resin is used. A pigment of a color to be colored is used as the pigment. Auxiliaries include surfactants (leveling agents, etc.), thickeners, regulators and the like. Resins, pigments, auxiliaries, touch agents, and water ratios are 20-40: 80-60 (total 100%. Weight ratio). As a coating method, brush coating, spraying, curtain coating, and roll coating are appropriately selected and used in a state containing an aqueous solution. The coating amount is 20 to 70 g / m ² , and water is evaporated by applying warm air to the surface after coating. The film thickness is 5 to 25 μm.

(3) The top coat layer is formed on the surface of the color coat layer. The thickness is 5 to 20 μm. The topcoat layer comes into contact with humans on the surface of natural leather for automobile seats. A person and the surface of natural leather for automobile seats come into contact. In this part, an unpleasant squeak noise may be generated, or a bad effect may be caused due to lack of wear resistance. For a person who uses an automobile seat, the automobile seat is required to have a soft feeling, a flexibility and a smooth touch, and a slimy feeling. In order to achieve such a characteristic, the polyurethane coating film is to be achieved by combining the added polyurethane fine particles and the additive mainly composed of silica fine particles. The composition for forming a natural leather coating film of the present invention for this purpose is as follows.

In the present invention, the following composition for forming a natural leather coating film for forming a topcoat coating film layer is used.
Two-part aliphatic polyurethane resin 0-50% by weight, two-part aliphatic polyurethane acrylic resin 0-50% by weight (two-part aliphatic polyurethane resin and two-part aliphatic polyurethane acrylic resin are 35 to 35% in total 50% by weight), 2 to 7% by weight of silica fine particles having a particle size of 0.3 to 30 μm, a plurality of particles having a Tg (glass transition temperature) of −60 to −20 ° C. and a particle size of 6 to 15 μm. 3-15% by weight of polyurethane resin particles having a diameter, 15 to 35% by weight of a crosslinking agent, 5 to 15% by weight of a silicone-based tactile agent, 0 to 5% by weight of a leveling agent, and 0 to 3% by weight of a thickener. A composition for forming a natural leather topcoat coating film, which comprises an aqueous emulsion containing a solid component (the total of each solid component is 100% by weight) and water.

About a resin component, it employ | adopts as the following weight% with respect to the whole quantity of the composition of the following ratios.
35 to 50% by weight of two-part aliphatic polyurethane resin, 35 to 50% by weight of two-part aliphatic polyurethane / acrylic resin, or 35 to 50 in total of two-part aliphatic polyurethane resin and two-part aliphatic polyurethane / acrylic resin Used as weight percent.
The first combination is composed only of a two-part aliphatic polyurethane resin (35 to 50% by weight).
The second combination is composed of only two-component aliphatic polyurethane / acrylic resin (35-50% by weight)
The third combination is a combination of the contents of the two-component aliphatic polyurethane resin and the two-component aliphatic polyurethane / acrylic resin (35-50 in total for the aliphatic polyurethane resin and the two-component aliphatic polyurethane / acrylic resin). weight%).
These combinations are a two-component aliphatic polyurethane resin and a two-component aliphatic polyurethane-acrylic resin that are added so that the feel of the natural leather film is in a preferable state in the finished state where the coat film is formed. Have similar characteristics, and the coating film is stable and the coating film does not turn yellow.

The polyurethane resin fine particles have a Tg of −60 to −20 ° C., and the fine particles have a particle size of 6 μm to 15 μm. The content of the polyurethane resin fine particles having a plurality of particle sizes in the solid content of the composition for forming a top coat film is 3 to 15% by weight. The polyurethane resin particles have a slimy feeling in addition to the matte. Make it difficult to generate squeak noise. Effective for reducing squeak noise.
The silica fine particles used at the same time are used for obtaining a matte effect that prevents the coating film from being shiny. Silica fine particles can achieve a matte effect, but if silica fine particles are used, the tactile sensation tends to be dry (a dry and dry feeling opposite to the feeling of slimming) and also causes the generation of squeak noise. It is silica fine particles having a particle size of 0.3 to 30 μm, and the content in the solid content of the composition for forming a topcoat coating film is 2 to 7% by weight.
By adding and using polyurethane resin fine particles to the silica fine particles that have been conventionally used, it is effective in reducing the squeak noise and preventing it.

15 to 35% by weight of the crosslinking agent is an essential component that acts on the resin component. The polymer of the top coat layer is adjusted.

The silicone-based tactile agent 5 to 15% by weight is an essential component. This is useful for improving the tactile sensation added so that the tactile sensation of the natural leather film is in a preferable state in the finished state where the top coat film is formed.

Leveling agents 0 to 5% by weight and thickeners 0 to 3% by weight are optional components.
Appropriately considering the properties.

The conditions for forming the topcoat layer using the composition for forming a natural leather coating film to form the topcoat layer are as follows.
As a coating method, brush coating, spraying, curtain coating, and roll coating are appropriately selected and used in a state containing an aqueous solution. The coating amount is 20 to 70 g / m ² , and water is evaporated by applying warm air to the surface after coating. The film thickness is 5 to 25 μm.

The two-component aliphatic polyurethane is as follows. Two-part aliphatic polyurethanes are aqueous and are used as paints. When forming a coating film on natural leather, an aqueous polyol and an aqueous polyaliphatic isocyanate are mixed and reacted at the time of use. Although the two-part aliphatic polyurethane has a problem of pot life in which it is necessary to proceed with processing such as coating work within a certain time, in the case of the present invention, processing of natural leather takes about 6 hours. It does not cause any problems as work. The finished coating is stable.
Aliphatic isocyanates such as 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and 2,4,4- Modification of aliphatic isocyanates such as isocyanates such as trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane to modify uretdione groups, isocyanurate groups, urethane groups, allophanate groups, burette groups and / or The polyisocyanate mixture is prepared by reacting with a polyisocyanate having an oxadiazine group and reacting with a polyalkylene oxide polyether alcohol containing an ethylene oxide unit (described in Japanese Patent No. 2961475).
As the aqueous polyol, dimethylolbutanoic acid, dimethylolpentanoic acid, dimethylolheptanoic acid, dimethyloloctanoic acid, and dimethylolnonanoic acid, which are carboxyl group-containing diols, can be used. Among them, dimethylolbutanoic acid, dimethylolheptanoic acid, and dimethylolnonanoic acid are preferable from the viewpoint of industrial cost and the like, and dimethylolbutanoic acid is most preferable. A carboxyl group-containing diol can be obtained by a known synthesis method, and is usually obtained by subjecting an alkylaldehyde to an aldol condensation of a formalin in the presence of a basic catalyst and then oxidizing a aldehyde group by acting a peroxide ( (It is described in Japanese Patent No. 349396, JP-A-8-359884, etc.).
NCO / OH when mixing is in the range of 1.3 to 1.5.
The polyisocyanate component is completely reacted with the polymer polyol and the low molecular weight chain extender to obtain a polyurethane. A solvent that can be optionally separated thereafter is used.
Also, the group that can be neutralized is converted to a salt form and a dispersion is produced using water. Depending on the degree of neutralization and ionic group content, the dispersion can be dispersed very finely so as to have a substantially solution appearance.

For the two-component polyurethane, the following commercially available products can be used.
Finish PF, PE, PFM, Matting MA, HS, LV (above BASF). Aqualen Top 2002. A, 2003. A, 2006. B, 2007. A, 2020. A, D-2012. B, D-2017, D-2018. B (manufactured by Clariant). BAYDERM Finish 60UD, 61UD, 65UD, 71UD, 85UD, HAT, LB, Hydrolac HW-G, UD-2, AQUADERM Matt 200 (manufactured by LANXESS).
WD-21-163, WT-2586, WT-2511, WT-13-493, WT-13-486, WT-13-986, WT-2533, WT-2585, WT-13-992, WT-13- 492, WT-2524, RU-6125 (manufactured by Stahl).

Two-Part Aliphatic Polyurethane / Acrylic Emulsion The two-part aliphatic polyurethane / acrylic emulsion is well known and is described, for example, in JP-A-5-320299.
The urethane prepolymer having an isocyanate (—NCO) group at the end is mixed with an ethylenically unsaturated monomer having a hydroxyl group (—OH) and the isocyanate group of the former prepolymer and the hydroxyl group of the latter monomer. After obtaining a self-emulsifying modified prepolymer having an ethylenically unsaturated bond and an isocyanate group in the molecule by reacting at an equivalent ratio (-OH / -NCO) of 0.3 to 0.6, A polymerizable mixture prepared by mixing 100 to 1000 parts by weight of an ethylenically unsaturated monomer having an acrylic monomer as a main component in the presence of 100 parts by weight of a solid component of the self-emulsifying modified prepolymer. An aqueous polyurethane / acrylic resin emulsion can be obtained by emulsion polymerization of an aqueous dispersion of the above.
The urethane prepolymer having an isocyanate group at the terminal is as follows.
Examples of urethane prepolymer having an isocyanate group at the terminal include Journal of Coating Technology vol. 58, no. 738, July 1986, pages 49-51 and JP-A-59-138211, a polyol having a molecular weight of 200-4000 and a polyisocyanate compound having two or more isocyanate groups (—NCO). The urethane prepolymer obtained by the reaction is a urethane prepolymer having an isocyanate group at the terminal obtained by further increasing the molecular weight with a chain extender for urethane, which can be ionized with an acid or alkali to form a self-emulsifying urethane prepolymer. is there.
Examples of the polyisocyanate used as a raw material for the urethane prepolymer include aliphatic and alicyclic diisocyanates such as 1,4-butylene diisocyanate, 1,6-hexane diisocyanate, 1,4-diisocyanatobutane, and 1,6. -Diisocyanatohexane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,5-naphthene diisocyanate Etc.
Moreover, as polyols, they are used for general urethane products. For example, any of polyethers, polyesters, polyesteramides, polythioethers, polybutadiene glycols and the like can be used. Polyethers are produced by ring-opening addition polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc., using a compound having active hydrogen such as water, ethylene glycol, propylene glycol, glycerin and the like as an initiator material.
Polyesters include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, It can be obtained by condensation of saturated and unsaturated low molecular weight glycol such as dipropylene glycol and dibasic acid. Other polythioethers and polyacetals can also be used. In order to obtain these urethane prepolymers, the polyols are usually synthesized at a reaction temperature of about 30 to 150 ° C. by lowering the CPR of the polyols (according to JIS K1557 for CPR). In the synthesis, the polyisocyanate / polyol blending molar ratio is 0.5 to 2.5 moles of isocyanate groups per one hydroxyl group of the polyols.
As chain extenders, N-methyldiethanolamine, N-ethyldiethanolamine, N-oleyldiethanolamine, dimethylolpropionic acid, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butylene glycol, tetramethylene Glycol, hexamethylene glycol, 1,4-butanediol, neopentyl glycol, diaminoethane, 1,6-diaminohexane, piperazine, 2,5-dimethylpiperazine, 4,4'-diaminodicyclohexylmethane, 1,2- Propylenediamine, hydrazine and the like.
Examples of the ethylenically unsaturated monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 2-hydroxy-3-chloropropyl acrylate, acryloyloxyethyl hydrogen phthalate, β-hydroxyethyl-β-acryloyloxyethyl phthalate, 1,4-butylene glycol monoacrylate, N-methylol acrylamide, hydroxystyrene, vinyl alcohol, allyl alcohol, methallyl alcohol, isopropenyl alcohol, 1-ptynyl alcohol, ethylene Glycol monoacrylate, 1,4-butanediol monoacrylate and the like are used. The reaction product of the urethane prepolymer and the ethylenically unsaturated monomer having a hydroxyl group has a free -NCO group, but it is not preferable because it reacts with active hydrogen, so this -NCO group is not preferred because it is a masking agent such as glycerin or caprolactam. And ionized with acid or alkali. As the alkali, tertiary amines, ammonia and the like are used, and as the acid, an inorganic acid such as hydrochloric acid and an organic acid such as acetic acid are used.
The following products can be used when purchased and used.

  Hydrohole TS, CR-5 (manufactured by LANXESS). WT-7370, WT-21433, RH-6777, RH 6663, RH 6659, RH 6671, RH 6698 (manufactured by Stahl)

Silica fine particles Silica fine particles are used to obtain a matte effect that prevents the coating from being shiny. Silica has no problem in that it can achieve a matte effect.
When silica fine particles are used, the tactile sensation tends to be dry (a dry and dry feeling opposite to the slimy feeling), and also causes squeak noise.
As shown in the following experiment, it is effective to use a polyurethane resin matting agent in combination in order to sufficiently perform matting and to produce a slimy effect.
As a result of the effect of the polyurethane resin matting agent being inferior to that of the silica fine particles, it is not possible to use only the polyurethane resin matting agent in place of the silica fine particles.
The content of silica fine particles is preferably 2 to 7% by weight. If it is less than this, a sufficient matting effect cannot be obtained. If the amount is too large, the physical properties of the coating film such as wear resistance may be adversely affected.
The silica fine particles have an average particle size of 0.3 to 30 μm, preferably 1 to 10 μm, in particular 2 to 6 μm, preferably organically coated with an oil number of 150 to 400 according to ISO 787/5 It is also effective to use prepared silicic acid. When the particle size is large, the touch feels rough and is not preferable.
The polyurethane to silicic acid solid ratio of the dispersion is 2: 1 to 5: 1. Likewise, preferably the residue of such a dispersion upon ignition is 1-8%. These are described in the following publications (JP 2000-119511 A). Any of these may be purchased by specifying the particle size from commercial products.

  As the polyurethane resin fine particles, it was found by experiments shown below that fine particles having a particle diameter in the range of 6 μm to 15 μm can be used effectively. Commercially available polyurethane resin fine particles can be used. The polyurethane fine particles employed by the present inventors are as follows. For example, there are 6 μm (UCN-5070D) and 15 μm (UCN-5150D) (powder type) manufactured by Dainichi Seika Co., Ltd. About the usage-amount of a polyurethane resin fine particle, 3 to 15% is suitable from the following experiment, an Example, etc. If it is smaller than this range, the effect of improving the tactile sensation and squeak noise will be insufficient. If it is larger than this range, the physical properties such as wear resistance and rub resistance may be adversely affected.

In addition, the polyurethane resin fine particles include urethane beads A (manufactured by Nippon Chemical Paint Co., Ltd., particle size 6 μm, having a hydrophilic group, no dispersant required), urethane beads B (both Nippon Chemical Paint Co., Ltd.) Manufactured, particle size 6 μm, no hydrophilic group, presence of dispersant required), Art Pearl C-400 (particle size 15 μm, Tg is −13 ° C.), Art Pearl C-600 (particle size 10 μm, Tg is − Art Pearl C-800 (particle size 6 μm, Tg is −13 ° C.), Art Pearl P-400T (particle size 15 μm, Tg is −34 ° C.), Art Pearl JB-800T (particle size 6 μm, Tg is -34 ° C.), Art Pearl JB-400T (particle size 15 μm, Tg is −52 ° C.), Art Pearl JB-600T (particle size 10 μm, Tg is −52 ° C.), Art Pearl JB-800T (particle size 6 μm, T Her 52 ℃) (or higher, Negami Kogyo Co., Ltd.) and the like are commercially available. Using these polyurethane fine particles, it is clarified which range is effective as a particle size.

In order to confirm the effect of the urethane fine particles, the present inventors show the results of confirming the characteristics of the topcoat layer to which the urethane fine particles having a specific particle diameter are added. Regarding the silica fine particles, the present inventors have found from the conventional experience using the silica fine particles and the polyurethane fine particle-containing polyurethane resin that when the silica fine particles and the polyurethane resin fine particles are used in combination, about 10% by weight of the silica fine particles is used. I thought it was enough. Similarly, it was considered that the effect can be obtained by adding about 15% of the polyurethane resin.

In the above experiment, when silica fine particles are not used, only urethane fine particles are used (particle diameters 6, 7, 7, and 15 μm).
The solid content composition of the composition for forming a topcoat coating film used in the experiment is as follows.
(1) Blank 1
Two-part aliphatic polyurethane / acrylic resin 42.5% by weight, silica fine particles 10.4% by weight of particles having a particle size of 0.3 to 30 μm 12.3% by weight of silicone-based tactile agent, 31.6% by weight of crosslinking agent, leveling agent 2.0 wt%, thickener 0.6 wt% (water added to adjust total solids concentration to 34.0 wt%).
(2) Blank 2
Two-part aliphatic polyurethane acrylic resin 47.3% by weight, cross-linking agent 35.1% by weight, silicone-based tactile agent 12.3% by weight, leveling agent 2.3% by weight and thickener 0.7% (water To adjust the total solids concentration to 34.0% by weight).
(3) top1, top2, top3, top4
Two-part aliphatic polyurethane / acrylic resin 40.2% by weight, urethane fine particles 14.9% by weight, cross-linking agent 29.9% by weight, silicone-based tactile agent 12.3% by weight, leveling agent 2.0% and thickening Agent 0.6% (water added to adjust total solids concentration to 34.0% by weight).
The feeling of sliminess is evaluated in five levels by sensory test (average of 5 evaluators). The larger the value, the stronger the feeling of sliminess. The squeak noise is also evaluated in five levels by the sensory test (average of 5 evaluators). The squeak noise level 4 represents a case where almost no squeak noise is felt.
In the case of using urethane fine particles, it can be seen that the feeling of stickiness and squeak noise is improved from a particle size of 6 μm to a particle size of 15 μm. However, with respect to the gloss, the blank 1 to which the silica fine particles are added is good, whereas the top1 to top4 to which the urethane fine particles are added has a tendency to become glossy in the light resistance test, and the sensory test has a satin feel.・ The results with glossiness indicate that the use of urethane fine particles alone cannot solve the problem sufficiently.

The above table is an experimental example in which the combination of silica fine particles and polyurethane fine particles shows good results. The solid content composition of the composition for forming a topcoat coating film used in the experiment is as follows.
(1) Blank 3
Two-part aliphatic polyurethane resin 30.7%, Two-part aliphatic polyurethane acrylic resin 15.6% by weight, Silica fine particles having a particle size of 0.3-30 μm 5.5% by weight, Crosslinker 32.8% by weight 11.4% by weight of silicone-based tactile agent, 3.4% by weight of leveling agent and 0.7% by weight of thickener (total solid content concentration is 34.0% by weight).
(2) top5, top6
Two-part aliphatic polyurethane resin 26.2%, Two-part aliphatic polyurethane acrylic resin 13.3% by weight, Silica fine particles 4.7% by weight with a particle size of 0.3 to 30 μm, Polyurethane fine particles 14.6%, 28.0% by weight of a crosslinking agent, 9.8% by weight of a silicone-based tactile agent, 2.9% of a leveling agent, and 0.6% of a thickener (total solid content concentration is 34.0% by weight).
It was found that good results were obtained at 7 μm and 15 μm for the polyurethane fine particles. As for the quantitative relationship between the silica fine particles and the polyurethane fine particles, the ratio of 4.7% by weight of the silica fine particles and 14.6% by weight of the polyurethane traces is a good result. When the particle size of the silica fine particles is specific, it indicates that there is a good relationship between touch and gloss. And it was found that the physical properties were maintained without any particular influence.
When the polyurethane fine particle is 7 μm, the effect of improving the squeak noise is small.

A top coat comprising polyurethane resin fine particles having a specific particle diameter according to the present invention (when the particle diameter Tg is -60 to -20 ° C and the polyurethane resin fine particles having a particle diameter in the range of 6 µm to 15 µm is contained 3 to 1515 wt%). The result of investigating the relationship between the slip characteristics of the layers is shown in FIG.
The dotted line is the measurement result of KES.
The solid line represents the friction characteristics.
The solid content composition of the composition for forming a topcoat coating film used was 41.4% by weight of a two-component aliphatic polyurethane acrylic resin, 4.9% by weight of silica fine particles having a particle size of 0.3 to 30 μm, and 7 of polyurethane fine particles. 0.7% by weight, 30.7% by weight of crosslinking agent, 12.7% by weight of silicone-based tactile agent, 2.0% by weight of leveling agent and 0.6% by weight of thickening agent (adding water to a total solid concentration of 34%) Adjusted to 0.0% by weight).
“No fine particles” is obtained by removing silica fine particles and polyurethane fine particles from the above composition. Only silica is obtained by removing only polyurethane fine particles from the above composition.
It can be understood that when polyurethane particles having a particle diameter in the range of 6 μm and 15 μm are used, even if the friction characteristics are used, the measurement results of the characteristics by KES can be obtained stably with good results. When the particle size is large, it tends to be difficult to slip.
In the case of the polyurethane fine particles having a particle diameter of 15 μm, the case where it is judged that it is not preferable is included in some cases. In this case, if polyurethane fine particles of 15 μm or less such as 6 μm or 10 μm are used as a mixture, it is considered that the case where the particle size becomes 15 μm or exceeds this is eliminated. Therefore, it is effective to make a mixture of polyurethane fine particles having different particle diameters within the range of 6 μm and 15 μm.

  About a crosslinking agent, 23 to 37 weight% is used. The aqueous polyaliphatic isocyanate can be used as the crosslinking agent. This crosslinking agent is well known, and is described in, for example, Japanese Patent No. 2961475. By using an OH group comprising dimethylol alkanoic acid and polytetramethylene ether glycol, an aqueous polyurethane resin coating having a number average molecular weight of about 18000 to 35000 is obtained as an aqueous polyurethane resin (Japanese Patent No. 349396, JP-A-8- 359844). The number average molecular weight of the polyurethane resin is usually from 12,000 to 20000, more preferably in the range of 35,000, and about 70000 aqueous polyurethane is obtained. Here, the number average molecular weight is a numerical value obtained by dissolving 1% by weight of a polyurethane resin in tetrahydrofuran, measuring it by GPC (gelation chromatography), and converting it to polystyrene. The measurement of molecular weight uses this measuring method thereafter. The molecular weight of the polyaliphatic isocyanates and polyols involved in the reaction is adjusted according to the final polyurethane molecular weight target. Aliphatic isocyanates such as 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and 2,4,4- Modification of aliphatic isocyanates such as isocyanates such as trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane to modify uretdione groups, isocyanurate groups, urethane groups, allophanate groups, burette groups and / or A polyisocyanate mixture is prepared by reacting with a polyisocyanate having an oxadiazine group and reacting with a polyalkylene oxide polyether alcohol containing ethylene oxide units.

The silicone-based tactile agent used as the tactile agent is used in an amount of 7 to 13% by weight.
The silicone-based tactile agent is added so that the tactile sensation of the natural leather film is preferable in the finished state where the top coat film is formed. Examples include hydroxypolydimethylsiloxane, aminopolydimethylsiloxane, hydroxypolydiethylsiloxane, polydimethylpolyepoxide polysiloxane, hydroxypolydiphenylsiloxane, aminopolydiethylsiloxane, dialkylsiloxane (the alkyl group is a monovalent fat having 1 to 10 carbon atoms) Group hydrocarbon, and examples thereof include a methyl group, an ethyl group, and a decyl group. The molecular weight of the reactive silicone is about 200-10000, preferably 300-9000, more preferably 1000-5000.
As the silicone, a known silicone resin represented by the following general formula can be used.

ＲはＣＨ_３、又はＣ_６Ｈ_５である。
ｎは１０以上１００以下の整数である。
このシリコーンは改質したものを用いることができる。
改質されたシリコーンは２から３の官能性を有するポリジアルキル置換ポリシロキサンを意味する。このアルキル基は、それぞれ、１から１０個の炭素を有し、官能基はカルビノール、アミノ、チオール、エポキシなどの基であってよい。ヒドロキシポリジメチルシロキサン（例えば、ダウ社のＤＣ１２４８、ＱＡ−３６６７、信越化学株式会社のＸ−２２−１６０Ｃ）、アミノポリジメチルシロキサン（ダウ社のＤＣ−５３６ゲネシポリマー社のＧＰ−４）、ポリジアルポリエポキシドポリシロキサンなどがある。
これらの分子量は２００から１００００程度である。
又、反応性シリコーン、ポリオール及びイソシアネートを用いることができる（特開６３−３１７５１４号公報）。
摩擦力を低くすることができ、すべり特性を向上させることができ、耐摩耗性 などを向上させることができる。
購入して利用する場合には、以下の製品を使用できる。

R is CH ₃ or C ₆ H ₅ .
n is an integer of 10 or more and 100 or less.
A modified silicone can be used.
Modified silicone means a polydialkyl-substituted polysiloxane having a functionality of 2 to 3. The alkyl groups each have 1 to 10 carbons and the functional group may be a group such as carbinol, amino, thiol, epoxy. Hydroxypolydimethylsiloxane (eg, Dow DC1248, QA-3667, Shin-Etsu Chemical X-22-160C), aminopolydimethylsiloxane (Dow DC-536 Geneshi Polymer GP-4), polydialpolyepoxide Examples include polysiloxane.
Their molecular weight is about 200 to 10,000.
Also, reactive silicone, polyol and isocyanate can be used (Japanese Patent Laid-Open No. 63-317514).
The frictional force can be lowered, the sliding characteristics can be improved, and the wear resistance can be improved.
The following products can be used when purchased and used.

Rosilk 2229W, 2000 (above, manufactured by LANXESS).
HM-183, HM-51-760, HM-18-639, HM-21-720, HM-13-843 (manufactured by STAHL).
MELIO WF-5233, WF-5226 conc. (The above is made by CLARIANT). AQUADERM Additive SF, Additive GF (manufactured by LANXESS).
HM-13-632, HM-13-363, HM-13-843 (above STAHL)

With respect to the leveling agent, when the composition for forming a topcoat coating film is spray-coated on the surface of the color coat layer, the composition may be repelled by water droplets due to surface tension. In such a case, a top coat having a uniform film thickness is not formed, resulting in a quality problem. The leveling agent is added so that the composition for forming a topcoat coating film spreads uniformly on the color coat by preventing repelling due to surface tension.
Trisiloxanes such as polyether-modified trisiloxane, ethers such as polyethylene glycol ether, esters such as alkoxyalkyl phosphate esters, alkylallyl polyether alcohol, 2-amino-2-methyl-1-propanol, 3-methyl Alcohols such as 3-methoxy-1-butanol, ethanol and 2-propanol are used. You may mix and use these.
The following products can be used when purchased and used.

AQUADERM Fluid H, LEVELER MA65 (manufactured by LANXESS), MELIO LV03 (manufactured by CLARIANT), LCC LEVELER RS-7 (Dainippon Ink), comparative leveler LV3 (manufactured by Union Paint).

If the viscosity of the composition for forming the topcoat film is too low for the thickener, when the composition for forming the topcoat film is spray coated on the leather with embossing (uneven pattern) by embossing, There arises a problem that the composition flows in and fills the concave portion, while the convex portion becomes thin. Thickeners increase the viscosity of the composition and prevent such problems from occurring. On the other hand, if the viscosity is too high, there is a problem that the spray machine cannot spray due to nozzle clogging, so it is important to adjust to an appropriate viscosity.
A modified polyurethane resin, a modified polyacrylic resin, a higher alcohol such as 2- (2-ethoxyethoxy) -2-butoxyethanol, or the like is used.
The following products can be used when purchased and used.

RM1020 (manufactured by LANXESS), Adecanol UH-420 (Adeka), RM4442 (manufactured by STAHL), UW additive MO for leather and RO (Toupe).

Both the Taber abrasion test and the resistance to abrasion test are satisfactory. In addition, regarding heat aging (heat resistance), moist heat resistance, light resistance, and non-adhesiveness, it is shown that there are no particular problems when using polyurethane fine particles having particle sizes in the range of 6 μm and 15 μm. It was done.

The test method used for the above test will be described below.

Tactile sensory test (1) Tactile sensory test for squeak noise A test piece having a length of about 250 mm and a width of about 180 mm is prepared. Hold the painted surface inside, fold it in half, and squeeze it tightly between your thumb and forefinger. Slide the gripped leather back and forth with your ears (slip), and check for squeaking noises based on whether or not a gulp is heard. (Check the noise that occurs when sliding with a firm grip, and when it slips and slips.)
The sound “Gyu-Gyu” is set as “squeak”, the loud sound is evaluated as “1”, and the sound without sound is “5”. The evaluation is based on the evaluation of five panelists, and the integer rounded to the average is used as the evaluation score.
(2) Sensory test by touch for slimy feeling A test piece having a length of about 250 mm and a width of about 180 mm is prepared.
Affix the leather to the same size or acrylic board with double-sided tape. When pasting, do not paste the leather in a stretched state.
Place the test piece on the plate or acrylic plate.
The natural leather surface of the test object affixed to a board or an acrylic board is made to touch five evaluators, and the tactile sensation is evaluated in five stages.
One with a strong “feeling of slimming” which is one of the tactile sensation factors is expressed as “5”, and one with a weak (or not) feeling of slimming is expressed as “1”.
An integer obtained by rounding the average value of five panelists is used as the evaluation score.

  The coating film which consists of a basecoat layer, a color coat layer, and a topcoat layer was formed in the surface of the natural leather by the Example below at the finishing process, and the evaluation was performed. The contents of the formation of the base coat layer and the color coat layer up to the finishing process and the finishing process are the same, and only the contents of the top coat layer are as described below and evaluated.

Evaluation of gloss (1) Measured by gloss gross meter. The larger the value, the stronger the gloss.
(2) The change when light was applied under constant light resistance was observed. The case where the gloss became stronger before the light was applied was defined as a gloss up.
(3) Sensory test The sensory evaluation was performed on the strength of the gloss, the texture of the pear (the leather surface looks like a pear skin pattern), and the gloss.

About Taber-type abrasion test Having abrasion resistance is a performance that is particularly emphasized in natural leather for automobile seats. The abrasion resistance was evaluated by a Taber type abrasion test. A test piece having a diameter of 150 mm is attached to a table of a Taber type rotary wear tester, and a CS-10 wear ring with a load of 1 kg is placed on the test piece and the tester is moved (the rotation speed of the tester is 70 rpm). At the same time, the dust collector is activated. The number of tests is 2000 times, and the wear state of the subsequent coating film is visually observed to give a grade.
The grade of evaluation is as follows.
Grade 5: Not observed at all.
Grade 4: Slightly recognized, but disappointing.
Grade 3: Slightly but clearly recognized.
Grade 2: Somewhat remarkable.
Grade 1: Very remarkable.
If it is 4th grade or higher, it is judged that it is suitable as natural leather for automobile seats based on experience.

About resistance to scratching The durability of a coating film against scratching is measured.
The measurement procedure is as follows.
Two test pieces of natural leather to be measured having a length of 120 mm and a width of 30 mm are prepared. Match the painted surfaces of natural leather and set them on a Scott type fir tester (manufactured by Tester Sangyo Co., Ltd.). The grip width is 30 mm, and the clamp screw is tightened so that the test piece does not shift.
The paddy test is performed 2,000 times at a load of 1 kg, a moving distance of 50 mm, and a cycle reciprocating speed of 120 times / min. After the fir test, the crack and peeling of the coating film on the test piece are visually observed and judged.

About the formation of the base coat layer
(1) A base coat was formed on the surface of a natural leather substrate (with buffing). The procedure is as follows.
The base coat layer is a lowermost layer of the coating film layer, and is a layer for preparing unevenness on the surface of the leather and forming a layer stably on the upper surface. In forming this layer, a composition comprising a resin, a pigment, an auxiliary agent, a tactile agent, a leveling agent and water was applied to the leather surface.
The ratio of resin, pigment, and auxiliary agent to be a solid content was 60:15:25 (total 100%, weight ratio). A two-component polyurethane resin was used as the resin. The pigment of the color to be colored was used as the pigment. As the auxiliary agent, a surfactant, a thickener, a regulator, a matting agent, an anti-tacking agent and the like were used.
The ratio of resin, pigment, auxiliary agent, tactile agent and leveling agent, and moisture is 35:65 (total 100%. Weight ratio). As a coating method, brush coating, spraying, curtain coating, and roll coating are appropriately selected and used in a state containing an aqueous solution. The coating amount is 80 to 120 g / m ² , and water is evaporated by applying warm air to the surface after coating.
Various required wrinkles were applied by pressing (this time, it was performed on the base coat, but may be performed after the subsequent color coat or top coat).
The leather fiber is loosened and the texture is adjusted by the blanking process and the staking process (also in these processes, it may be performed after the color coat or top coat).
(2) A color coat was formed.
A color coat was formed on the base coat surface. The color coat layer is an intermediate layer of the paint curtain, and is a layer for causing pigments and dyes for coloring the leather to exist, and is provided on the base coat as viewed from the leather. In forming this layer, a composition comprising a resin, a pigment, an auxiliary agent, a crosslinking agent and water is applied to the leather surface. The ratio of the resin, the pigment, the auxiliary agent and the cross-linking agent as solid content is 60: 20: 10: 10 (total 100%, weight ratio). As the resin, a two-component polyurethane resin is used. A pigment of a color to be colored is used as the pigment. Auxiliaries include surfactants (leveling agents, etc.), thickeners, regulators, matting agents, anti-tacking agents and the like. The ratio of resin, pigment, auxiliary agent, tactile sensation, and moisture is 30:70 (total 100%. Weight ratio). As a coating method, brush coating, spraying, curtain coating, and roll coating are appropriately selected and used in a state containing an aqueous solution. The coating amount was 30 to 40 g / m ² , and water was evaporated by applying warm air to the surface after coating.
(3) A top coat was formed on the color coat surface. The top coat layer was the uppermost layer of the coating film, and the composition was as described below. The coating amount was 30 to 40 g / m ² , and the particle size and Tg (glass transition temperature) of the polyurethane fine particles were examined.

The result of the sensory evaluation which investigated the tactile sensation of the friction characteristic and generation | occurrence | production of a squeak noise when using the microparticles | fine-particles in a particle size in the range of 6 micrometers and 15 micrometers is shown (FIG. 2). Regarding the feeling of sliminess (horizontal axis), the vertical axis shows the condition about the difficulty of sounding squeak noise.
The solid content composition of the composition for forming a topcoat coating film used was 24.7% two-component aliphatic polyurethane resin, 17.6% by weight two-component aliphatic polyurethane / acrylic resin, and a particle size of 0.3 to 30 μm. Silica fine particles 4.9% by weight, polyurethane fine particles 9.2% by weight, cross-linking agent 29.6% by weight, silicone-based tactile agent 10.3% by weight, leveling agent 3.1% by weight and thickener 0.6% by weight. % (Total solid concentration is 34.0% by weight).
In the figure, “no fine particles” is a composition obtained by removing silica fine particles and polyurethane fine particles from the above composition, and “silica fine particles only” is a composition obtained by removing polyurethane fine particles from the above composition.
The components of the top coat film formed on the surface of natural leather are as follows.
Two-part aliphatic polyurethane resin 24.7%, Two-part aliphatic polyurethane / acrylic resin 17.6% by weight, Silica fine particles 4.9% by weight with a particle size of 0.3-30 μm, Polyurethane fine particles 9.2% by weight 29.6% by weight of a crosslinking agent, 10.3% by weight of a silicone-based tactile agent, 3.1% by weight of a leveling agent and 0.6% by weight of a thickener (total solid content concentration is 34.0% by weight).
In all cases where the polyurethane fine particles were added, the squeak noise and the slimy feeling were improved as compared with the case of no fine particles and only the silica fine particles.
However, the improvement effect was different depending on the particle size and TG of the urethane fine particles. It shows that the larger the particle size of the urethane fine particles and the softer (the lower the Tg), the less squeak noise is produced and the greater the feeling of sliminess.
It can be seen that when the particle size is 10 μm or more to 15 μm, there is a feeling of sliminess and it is difficult to make a squeak noise. From 6 to 7 μm, it can be seen that it feels dry and squeaky sounds are likely to sound. As for the squeak noise, the larger the particle size of the urethane fine particles and the softer (the lower Tg), the harder the squeak noise is produced.
If the polyurethane fine particle is less than 6 μm, it is not sufficient in eliminating the squeak noise. Further, the larger the particle size, the more the surface feel becomes powdery, which indicates that it is not suitable when it exceeds 15 μm.
Also in this case, if the particle size of the polyurethane fine particles is 15 μm which is the limit value, it may indicate that the particle size may not be sufficient, and it is necessary to slightly reduce the influence when using the 15 μm polyurethane fine particles. It shows that it is effective to mix polyurethane fine particles having a small particle system.
As for TG, the best results were obtained when TG-54 ° C. and particle size of 15 μm. Even when TG is low (−13 ° C.), the effect of improving the tactile sensation is recognized, but the effect is small when the particle size is 6 μm. TG is preferably in the range of -20 to -60 ° C.
As for gloss, in all cases, good results were obtained. The Taber abrasion was 5 in all cases, and the abrasion resistance was normal in all cases, and the physical properties were not lowered by the combined use of silica fine particles and polyurethane fine particles.

Furthermore, using the composition for forming a topcoat coating film having a solid content of the blank 1 in Table 1, the effect of using silica fine particles having a particle size of 0.3 to 30 μm and polyurethane fine particles having a particle size of 7 μm or 15 μm in combination, The case where the addition amount of polyurethane fine particles was reduced was examined.
(1) Blank 1
Two-part aliphatic polyurethane / acrylic resin 42.5% by weight, silica fine particles 10.4% by weight of particles having a particle size of 0.3 to 30 μm 12.3% by weight of silicone-based tactile agent, 31.6% by weight of crosslinking agent, leveling agent 2.0 wt%, thickener 0.6 wt% (total solids concentration is 34.0 wt%).
(2) top7, top8
Two-part aliphatic polyurethane / acrylic resin 41.4% by weight, silica fine particles 4.9% by weight, particle size 0.3-30 μm, polyurethane fine particles 7.7% by weight, silicone-based tactile agent 12.7% by weight, crosslinked 30.7% by weight of agent, 2.0% by weight of leveling agent, 0.6% by weight of thickener (total solid content concentration is 34.0% by weight).
The components of the top coat film formed on the surface of natural leather are as follows. Two-part aliphatic polyurethane / acrylic resin 41.4% by weight, silica fine particles 4.9% by weight, particle size 0.3-30 μm, polyurethane fine particles 7.7% by weight, silicone-based tactile agent 12.7% by weight, crosslinked 30.7% by weight agent, 2.0% by weight leveling agent, 0.6% by weight thickener (100% by weight in total).
The results are shown in Table 3. Even when the addition amount of the polyurethane resin was 7.7% by weight, the effect of improving the feeling of sliminess and squeak noise was recognized. When the particle size was 7 μm, the effect of improving squeak noise was slightly small.

It is considered that the combination of silica fine particles and polyurethane fine particles in a paint can be used as a surface treatment technique. It proposes the transfer of technology to various fields.

Claims (3)

  35 to 50% by weight of two-part aliphatic polyurethane resin, 35 to 50% by weight of two-part aliphatic polyurethane / acrylic resin, or 35 to 50 in total of two-part aliphatic polyurethane resin and two-part aliphatic polyurethane / acrylic resin 6% by weight of polyurethane resin fine particles having a particle size of 2 to 7% by weight, a particle size of 0.3 to 30 μm, a Tg of −60 to −20 ° C., and a particle size of 6 to 15 μm. Solid content consisting of -15% by weight, 15-35% by weight of crosslinking agent, 5-15% by weight of silicone-based tactile agent, 0-5% by weight of leveling agent, 0-3% by weight of thickening agent And 100% by weight) and an aqueous emulsion containing water.   35 to 50% by weight of two-part aliphatic polyurethane resin, 35 to 50% by weight of two-part aliphatic polyurethane / acrylic resin, or 35 to 50 in total of two-part aliphatic polyurethane resin and two-part aliphatic polyurethane / acrylic resin 3% by weight of polyurethane resin fine particles having a particle size of 2 to 7% by weight, a particle size of 0.3 to 30 μm, a Tg of −60 to −20 ° C., and a particle size of 6 to 15 μm. -15% by weight, cross-linking agent 15-35% by weight, silicone-based tactile sensation agent 5-15% by weight, leveling agent 0-5% by weight, and thickener 0-3% by weight (the total of each solid component is 100% by weight) A top coat formed by coating on the surface of natural leather. 3. A polyurethane resin according to claim 2, wherein a base coat layer and a color coat layer are formed after passing through a preparation step before tanning, a tanning step, a retanning / dyeing / greasing step, and a drying step, and further on the surface of the color coat. A natural leather for automobile seats, wherein a top coat containing fine particles is formed.

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