JP2574004B2 - Synthetic leather with excellent texture - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a synthetic leather having an improved feel.

[Conventional technology]

BACKGROUND ART Synthetic leather using polyurethane as a skin material has been widely used in various fields as a material for shoes, clothing, furniture, and vehicle seats such as automobiles because of its good feel and appearance. Hand feeling and durability are strongly demanded for the synthetic leather, especially flexibility,
Demands on quality such as heat resistance, hydrolysis resistance, light resistance, and mold resistance are becoming more and more severe.

In order to satisfy these required performances, for example, the type of polyurethane used for synthetic leather and its component composition are changed. In addition, various studies have been conducted to satisfy the above-mentioned required performance by selecting a fiber base material in synthetic leather, bonding and multi-layering the skin layer, and a combination thereof.

For example, Japanese Patent Publication No. 55-23956 discloses a synthetic leather excellent in light resistance and hydrolysis resistance by disclosing a special polycarbonate-based polyurethane urea elastomer. JP-A-61-14221 discloses 3-methyl-
It has been suggested that a polyurethane using a polyester polyol composed of 1,5-pentanediol and a dicarboxylic acid has excellent mold resistance, and that the polyurethane is applicable to synthetic leather. Japanese Patent Application Laid-Open No. 62-22817 discloses that a polyurethane using a polymer polyol containing a 2-methyl-1,8-octanediol unit has excellent hydrolysis resistance, and a polyester-based polyurethane solution containing the unit is used. It is disclosed that a synthetic leather can be obtained by applying a coating agent or an impregnating agent to a substrate such as a fiber.

In Japanese Patent Publication No. 59-1822, the adhesive layer is made of a polyether-based polyurethane and the skin layer is made of a polycarbonate-based polyurethane, so that it is excellent in hydrolysis resistance and light resistance and durable for long-term use. It is said that leather can be obtained. Further, in JP-A-58-144185, a polycarbonate-based polyurethane adhesive layer, a polyester-based polyurethane intermediate layer comprising a glycol carboxylic acid having 4 or more carbon atoms, and a polycarbonate-based polyurethane skin layer are successively provided on a microporous composite fiber base material. A laminated flexible vehicle synthetic leather is disclosed.

[Problems to be solved by the invention]

However, in general, polyester-based polyurethane is most widely used, and synthetic leather sufficiently satisfactory in any performance has not yet been obtained. Therefore, further expansion of the market is eagerly desired but not fulfilled.

A first object of the present invention is to provide a synthetic leather which meets at least the various performance requirements described above.

A second object of the present invention is to provide a soft synthetic leather having a good feel.

Another object of the present invention is to provide a novel synthetic leather, thereby enabling the development of new uses of the synthetic leather. Still other objects of the present invention will become more apparent from the following description.

[Means for solving the problem]

The present inventor has conducted intensive studies in view of such a situation,
Formula (I) A polyurethane having a 100% modulus of 10 to 100 kg / cm ² obtained by reacting a polymer diol containing 5% by weight or more of a group represented by the formula with an organic diisocyanate and a chain extender; As an adhesive with a polyurethane prepolymer obtained by reacting a diol and an organic diisocyanate as a main component and a crosslinking agent as a curing agent,
It has been found that by providing an adhesive layer on a fiber base material and a skin layer thereon, a synthetic leather having good texture and excellent hydrolysis resistance can be obtained.

 First, the skin material used in the present invention will be described in detail.

As the compound capable of forming the structural unit of the group represented by the formula (I), 2-methyl-1,8-octanediol is preferable. Indicated by

As the high molecular diol in the present invention, a polyester polyol or a polycarbonate polyol containing a group represented by the formula (I) as a diol residue is preferable. Hereinafter, these polymer diols will be described.

The polyester polyol or polycarbonate polyol is made using 2-methyl-1,8-octanediol or a mixed diol containing the diol.
Diols that can be used in combination with 2-methyl-1,8-octanediol include ethylene glycol and 2-methyl-1,
3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol,
9-nonanediol, dodecanediol, diethylenediol, neopentyl glycol and the like, but flexibility,
Larger carbon number is preferable in terms of heat resistance and durability 1,6
Diols having 6 or more carbon atoms, such as hexanediol, 1,9-nonanediol and dodecanediol, are suitable. In addition, the use of a small amount of a polyhydric alcohol such as trimethylolpropane, glycerin, and pentaerythritol in combination with the above-mentioned diol may not cause any problem.

The polyester polyol is obtained by a reaction between the above diol and dicarboxylic acid.

The structural unit of the dicarboxylic acid has the formula (III) And / or formula (IV) It is preferred that In the above formula (III), n is 1
Examples of the aliphatic dicarboxylic acid which represents an integer of ~ 12 and which can form the formula (III) include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecane diacid and the like. More preferred are adipic acid, azelaic acid and sebacic acid. These dicarboxylic acids may be used alone or in combination of two or more.
In the above formula (IV), Ar is a divalent aromatic hydrocarbon residue having 6 to 10 carbon atoms, for example, a phenylene group or a naphthylene group. Specific examples of the aromatic dicarboxylic acid capable of forming the formula (IV) include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid,
Examples thereof include 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the like, and arbitrary mixtures thereof. More preferred are terephthalic acid and isophthalic acid.
Further, an alkyl ester thereof derived from the above aromatic dicarboxylic acid can also be used as a dicarboxylic acid source.

The method for producing the polyester polyol is not particularly limited, and a known polyester condensation polymerization means can be applied. For example, the structural units (I), (III) and (I)
The compounds capable of producing V) are charged in the desired proportions and are esterified or transesterified at 150-250 ° C. in the presence or absence of an esterification and / or transesterification catalyst, and thus obtained. It can be produced by subjecting the reaction product to further polycondensation under high vacuum at 200 to 300 ° C.

Next, a polycarbonate polyol is synthesized by using the above-mentioned diol. (A) A method obtained by reacting a diol with phosgene. (B) A method of synthesizing by transesterification between a diol and an alkylene carbonate. (C) A diol and a dialkyl carbonate or diaryl. There is a method of synthesizing by transesterification with carbonate, and those synthesized by any method can be used. Preferably, both polyester polyols and polycarbonate polyols have an average molecular weight in the range of 600 to 5,000.

If the number average molecular weight of these polyols deviates greatly from the above range, the flexibility of the skin layer is impaired, which is not preferable.

In the present invention, the organic diisocyanate used for producing the polyurethane polyol used as the polymer having a group represented by the formula (I) in the molecule includes a known fat containing two isocyanate groups in the molecule. And aliphatic, cycloaliphatic and aromatic organic polyisocyanates. Examples thereof are 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4 '
-Dicyclohexylmethane diisocyanate. Among them, 4,4'-diphenylmethane diisocyanate or isophorone diisocyanate is preferred.

Chain extenders also include those commonly used in the polyurethane industry, ie, compounds containing at least two hydrogen atoms that can react with isocyanates.
Examples include ethylene glycol, 2-methyl-1,3
-Propanediol, 1,4-butanediol, 1,6-hexanediol, xylylene glycol, 3-methyl-1,
5-pentanediol, bishydroxyethoxybenzene, neopentyl glycol, 2-methyl-1,8-octanediol, 1,9-nonanediol, isophoronediamine, hydrazine, dihydrazide, trimethylolpropane, glycerin and the like. Among them, ethylene glycol, 1,4-butanediol, isophoronediamine and the like are preferable.

In the present invention, a method for producing a polyurethane serving as a skin material is as follows. A polymer diol is reacted with an excess of an organic diisocyanate to produce a prepolymer having a terminal isocyanate, and then a chain extender such as a diol or a diamine is reacted to form a polyurethane. The urethanization reaction may be performed without a solvent, or may be performed in a solvent inert to isocyanate groups. As a solvent at that time, dimethylformamide, toluene, methyl ethyl ketone, tetrahydrofuran, butyl acetate, or the like can be used.

As described above, a polyurethane for a skin material is prepared from a polyester polyol or a polycarbonate polyol, a diisocyanate and a chain extender, and it is necessary that the polyurethane contains a component having a structural unit of the formula (I). The polyurethane having a structural unit represented by the formula (I) has a large carbon number of 9 and has a side chain, a low glass transition temperature, and impairs crystallinity. When used as a skin material, it is considered that a synthetic leather having excellent hydrolysis resistance and cold resistance, and being very flexible and having a good feeling can be obtained. This effect is due to the fact that the component represented by the formula (I) contains 5% by weight of the main ingredient.
It is necessary to contain the above, and if it is less than 5% by weight, there is no effect.

A polyester polyol or a polycarbonate polyol having a group represented by the formula (I) alone or a mixture thereof; or a polyester polyol, a polycarbonate polyol, a polycaprolactone or a polyvalero having no such group and the polyol represented by the formula (I). It is also possible to use together with an ether polyol such as a lactone polyol, polytetramethylene glycol, polypropylene glycol or polyethylene glycol. In this case, a mixture obtained by reacting a mixture of these polyols with a diisocyanate and a chain extender may be used, or a mixture obtained by reacting each polyol with a diisocyanate and a chain extender may be used. May be. In any case, it is necessary that the polyurethane has at least 5% by weight of the group represented by the formula (I).

The skin layer in the present invention has a 10% modulus at 100% modulus.
There needs to be a ~100kg / cm ^2. If it is less than 10 kg / cm ² , the abrasion resistance will be poor, and if it exceeds 100 kg / cm ² , the effect of using a flexible main agent containing the formula (I) will be lost. This 100% as the number of hard segments increases
Be careful as the modulus increases.

Further, the skin layer may be used by dividing into an intermediate layer and a top layer (upper layer). In this case, it is desirable to use a flexible material having a low 100% modulus for the intermediate layer and a slightly high 100% modulus for the top layer in consideration of abrasion resistance.

When the intermediate layer and the top layer are used separately, foaming the intermediate layer makes it more flexible.

On the other hand, as a polyurethane for an adhesive, a polyurethane resin handbook [Nikkan Kogyo Shimbun (1987)]
Conventional adhesives such as those described on page 8 can be used. For example, one or two or more of polyester polyols obtained from diols and dicarboxylic acids, polyols such as polycaprolactone and polyvalerolactone, polycarbonate polyols, polytetramethylene glycol, and polyether polyols such as polypropylene glycol and polyethylene glycol. A polyurethane comprising a main agent obtained by reacting a polymer diol with an organic diisocyanate and a crosslinking agent is used. Further, a polyurethane obtained by mixing two or more kinds of main agents obtained by reacting these polyols with an organic diisocyanate and combining the mixture with a crosslinking agent may be used.

Here, the polyester polyol or the polycarbonate polyol is ethylene glycol, 2-methyl-1,
3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol,
It can be prepared in the same manner as in the case of the skin material using a diol such as 1,9-nonanediol, 2-methyl-1,8-octanediol, dodecanediol, diethylene glycol or neopentyl glycol.

Examples of the organic diisocyanate include known aliphatic, alicyclic, and aromatic organic polyisocyanates containing two isocyanate groups in the molecule, and in particular, 4,4'-diphenylmethane diisocyanate, p-phenylene Examples thereof include diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

Among them, diisocyanates having isocyanate groups having different reaction activities are preferable. In particular, isophorone diisocyanate, 2,4-tolylene diisocyanate or a mixture containing these as a main component is preferred. In addition to the above-mentioned organic dicyanate, a small amount of a polyfunctional polyisocyanate such as trimethylolpropane or triisocyanate obtained by adding 3 mol of tolylene diisocyanate to 1 mol of glycerin can be used together.

At this time, if desired, a suitable chain extender may be used. Examples of the chain extender include a chain extender commonly used in the polyurethane industry, that is, a compound containing at least two hydrogen atoms capable of reacting with isocyanate. Included. Examples include ethylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,6-
Hexanediol, xylylene glycol, 3-methyl-1,5-pentanediol, bishydroxyethoxybenzene, neopentyl glycol, 1,9-nonanediol, isophoronediamine, hydrazine, dihydrazide,
Trimethylolpropane, glycerin and the like.
In addition, as for a specific operation method for obtaining the above polyurethane polyol, a known technique of a urethane reaction is used. For example, a polyester polyol having a number average molecular weight of 600 to 5,000 and a low molecular compound having active hydrogen if desired are mixed and preheated to about 40 to 100 ° C., and then the ratio of isocyanate groups to the number of active hydrogen atoms of these compounds ( NCO / OH) is obtained by adding an organic diisocyanate in an amount of 1 or less and reacting at 50 to 120 ° C. for several hours. The above reaction may be carried out in the presence of an inert organic solvent for the isocyanate group. If desired, conventional urethanization catalysts such as organotin compounds and tertiary amines may be used. When the production process is performed in the presence of an organic catalyst, the solid content of the final mixture is about 10 to
It is advantageous to determine the amount of organic catalyst used so as to be 90% by weight, preferably 20-80% by weight.

The polyurethane polyol thus obtained preferably has a number average molecular weight of 3,000 to 70,000 from the viewpoint of performance when used as an adhesive.

The polyester polyol or polyurethane polyol used in the present invention preferably has at least two hydroxyl groups at the molecular terminals.

In the present invention, the polyurethane polyol thus obtained is used as a main component, and a compound having at least three groups capable of reacting with hydroxyl groups of the polyol is blended as a crosslinking agent to form an adhesive.

Examples of the cross-linking agent used here include organic polyisocyanates, epoxy resins, and mixtures thereof, and organic polyisonates are particularly preferable. Preferred organic polyisocyanates include compounds having three or more isocyanate groups in the molecule, such as trimethylolpropane, glycerin, and all hydroxyl groups such as pentaerythritol. Compounds.

When a crosslinking agent is used in the adhesive of the present invention, the mixing ratio of the main agent and the crosslinking agent is 1 to 1 in the equivalent ratio of all isocyanate groups of the crosslinking agent to all hydroxyl groups of the main agent (NCO / OH).
A range of 20 to 1 to 10 is particularly preferable. When the equivalent ratio is 1 or less, the heat resistance is poor, and when it exceeds 20, the adhesive strength is reduced and the flexibility is lost, but this is because the hardness of the adhesive increases due to the increase of the isocyanate. It is caused by stress concentration.

As described above, as the adhesive, a main agent composed of a polymer diol and an organic diisocyanate used in ordinary synthetic leather and a polyurethane obtained from a cross-linking agent can be used, and among them, it is more flexible and has excellent hydrolysis resistance. It is preferable to use a polyurethane containing a group represented by the following formula (II).

(Where R ¹ represents a methyl group or an ethyl group, R ² represents a hydrogen atom, a methyl group, an ethyl group, a hydroxymethyl group or a hydroxyethyl group, and n and m represent n + m ≧ 2, preferably n + m ≧ 4. As a compound capable of forming a structural unit of a group represented by the formula (II), for example, 2-methyl-1,3-propanediol,
3-methyl-1,5-pentanediol and the like are conceivable.
The other diol used in combination with the compound capable of forming the group represented by the formula (II) preferably has 5 or more carbon atoms.
This is because, as the number of carbon atoms increases, the glass transition temperature generally decreases and the hydrolysis resistance and heat resistance are excellent. However, using only a long-chain diol increases the crystallinity, and tends to result in a hard polyurethane. On the other hand, if a material having a group represented by the formula (II) is contained, the crystallinity is inhibited, so that a flexible polyurethane as a whole can be obtained. It is desirable that the group represented by the formula (II) contains at least 5% by weight of the polyurethane as the main component of the adhesive.

The 100% modulus of the polyurethane used as the adhesive layer is preferably smaller than that of the skin layer.

Synthetic leather can be produced, for example, by the following transfer method.

First, a solution of the polyurethane for skin material is applied on release paper with a doctor knife, and dried with hot air at 90 to 110 ° C. for 2 minutes. The thickness of the obtained skin layer film varies depending on the final use, but the concentration of the solution and the amount of application are usually adjusted to 10 to 100 µm.

Next, an adhesive polyurethane solution is applied onto the skin layer, and a base fabric is laminated with an appropriate gap of a laminating roll, followed by hot-air drying at 90 to 110 ° C. for 2 minutes. If a resin having a resin content of 30 to 50% by weight in the adhesive polyurethane solution is applied in an amount of 60 to 150 g / m ² , an adhesive layer having a thickness of several μm after drying will be formed.

Thereafter, it is aged at 40-60 ° C for 2-3 days. Thereafter, the release paper is peeled off, and the surface is finished several times with a gravure roll as needed.

Base fabric is synthetic fiber, for example, polyamide, polyester,
Knitted cloth, woven cloth, nonwoven cloth or impregnated cloth obtained from semi-synthetic fibers such as vinylon, polyacrylonitrile, etc., or rayon, Kyupura, acetate, or the like, or natural fibers, such as silk, wool, cotton, or hemp, are used. be able to. Of course, the type and material of the base fabric are important factors that determine the texture of the synthetic leather.

In the production of synthetic leather, polyurethane is sometimes used as a finish on the surface, but the polyurethane used as a skin material in the present invention can also be used as a finish. Also in this case, it is preferable to use a polyurethane having a group represented by the formula (II).

It should be noted that coloring by mixing a pigment or a dye with the adhesive and / or the polyurethane for the skin material may be performed at all. It may be dyed after being made into synthetic leather.

〔Example〕

 Hereinafter, specific examples will be described.

In the table, the flexibility was compared and judged by touch.

◎ Very good ○ Good △ Slightly hard × Very hard Hydrolysis resistance is the surface stickiness that occurs when synthetic leather is left for 5 to 10 weeks in an atmosphere of 70 ° C. and 90% relative humidity (Jangle test condition). Evaluation was made based on surface cracks and peeling of the skin layer.

◎ Very good ○ Good △ Slightly bad × Very bad (Example of making synthetic leather) Using a knife coater, apply a polyurethane solution for skin layer (solids concentration 20%) on release paper to a dry thickness of 25 μm. And dried by heating at 100 ° C. for 3 minutes to form a polyurethane film. Next, a polyurethane solution for an adhesive (solid content concentration: 40%) was applied to the skin layer using a knife coater so as to have a basis weight of 120 g / m ² , and immediately mixed with Tetron as a warp and rayon as a weft. The non-raised surface of the blanket is stuck and pressed by a laminating roll. After drying at 100 ° C for 2 minutes, aging is performed at 50 ° C for 3 days.

When two layers, a top layer and an intermediate layer, are provided as the skin layer, a dry film is formed on the release paper in sequence from the polyurethane solution for the top layer and the intermediate layer.

Examples 1 to 10 Synthetic leather was obtained in the configuration shown in Table I in accordance with the above-described synthetic leather production example, using a polyurethane comprising a polyester diol, an organic diisocyanate and a chain extender as a skin material.

The flexibility and hydrolysis resistance of the obtained synthetic leather were measured, and the results are shown in Table I. All synthetic leathers had a good feeling and were flexible.

Examples 11 to 18 Table II shows the results when synthetic leather was obtained in the same manner as in Example 1 except that a polyurethane comprising a polycarbonate diol, an organic diisocyanate and a chain extender was used as a skin material. All synthetic leathers had a good feeling and were flexible.

 The relationship between the abbreviation and the compound is as follows.

EG ethylene glycol BD 1,4-butanediol HD 1,6-hexanediol MPD 3-methyl-1,5-pentanediol ND 1,9-nonanediol MOD 2-methyl-1,8-octanediol IPDA isophoronediamine PCL Polycaprolactone PMVL Polymethyl valerolactone PBA Polybutylene adipate PTG Polytetramethylene glycol PPG Polypropylene glycol IPDI Isophorone diisocyanate HDI Hexamethylene diisocyanate TDI Tolylene diisocyanate MDI 4,4'-Diphenylmethane diisocyanate TMP (TDI) ₃ Trimethylolpropane tolylene isocyanate adduct TMP (HDI) ₃ trimethylol propane hexamethylene diisocyanate adduct TMP (IPDI) ₃ trimethylol propane isophorone diisocyanate adduct PHC polyhexamethylene car Sulfonate (Effects of the Invention) As described above, according to the present invention, by using a polyurethane containing a specific structural unit as a skin material and using a crosslinked polyurethane as an adhesive layer, the feeling is good and the flexibility is high. Further, a synthetic leather having good durability is provided.

Claims (1)

(57) [Claims] 1. A polyurethane obtained by reacting a polymer diol, an organic diisocyanate and a chain extender, wherein the polymer diol has the formula (I) A polyurethane material containing 5% by weight or more of a group represented by and having a 100% modulus of 10 to 100 kg / cm ² as a skin material,
Synthetic leather using polyurethane obtained by reacting a main agent obtained by reacting a polymer diol and an organic diisocyanate with a crosslinking agent as an adhesive.