JP2574003B2 - Synthetic leather with good 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 made to satisfy the above-mentioned required performance by selecting a fiber base material in synthetic leather, forming multilayers of an adhesive layer and a skin layer, and combining them.

For example, Japanese Patent Publication No. 55-23956 proposes 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-1,5
-It has been suggested that a polyurethane using a polyester-based polyol composed of pentanediol and a dicarboxylic acid has excellent mold resistance, and that the polyurethane is applicable to synthetic leather. JP-A-62-22817 discloses that a polyurethane using a high molecular 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.

Furthermore, in JP-B-59-1822, the adhesive layer is made of polyether-based polyurethane and the skin layer is made of polycarbonate-based polyurethane, so that it has excellent hydrolysis resistance and light resistance, and is 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 composed of a glycol carboxylic acid having 4 or more carbon atoms, and a polycarbonate-based polyurethane skin layer are sequentially formed on a microporous composite fiber substrate. 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 inventors have made intensive studies in view of such a current situation, and as a result, the formula (I) By using a polyurethane using a polymer diol containing a group represented by an adhesive, and by using a polyurethane obtained by reacting the polymer diol with a diisocyanate and a chain extender as a skin material, excellent flexibility, And heat resistance,
We have found that synthetic leather with excellent durability can be obtained. That is, in a polyurethane obtained by reacting a main component obtained by reacting a polymer diol with an organic diisocyanate and a crosslinking agent, the main component contains 5% by weight of a group represented by the formula (I).
Polyurethane containing above and having a 100% modulus of 10 to 100 kg / cm ² is used as an adhesive layer, and polyurethane obtained by reacting a polymer diol with a diisocyanate and a chain extender is used as a skin material to adhere to a fiber base material. It has been found that by providing an agent layer and a skin layer thereon, a synthetic leather having a good texture and excellent hydrolysis resistance can be obtained.

First, the adhesive 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,
The compound has the formula: 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,
There are 1,9-nonanediol, dodecanediol, diethylenediol, neopentyl glycol, etc., but the larger the carbon number is, the more preferable in terms of flexibility, heat resistance and durability.
Diols having 6 or more carbon atoms, such as 1,6 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 mixtures thereof in any ratio. 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, the synthesis of polycarbonate polyol is carried out by using the above-mentioned diol (a) a method obtained by reacting diol and phosgene (b) A method of synthesizing by transesterification reaction between diol and alkylene carbonate (c) diol and dialkyl carbonate or diaryl There is a method of synthesizing by transesterification with carbonate, and those synthesized by any method can be used. The average molecular weight of both the polyester polyol and the polycarbonate polyol is preferably in the range of 600 to 5,000. When the number average molecular weight of these polyols deviates significantly from the above range, normal adhesive strength, wettability,
The decrease in initial adhesive strength, hot water resistance, etc. is undesirably increased.

In the present invention, the organic diisocyanate used for producing the polyurethane polyol used as a polymer having a group represented by the formula (I) in the molecule includes a known aliphatic compound having two isocyanate groups in the molecule. And alicyclic and aromatic organic polyisocyanates, particularly 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexa Methylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and the like. 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 diisocyanate, 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. Can be 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, after mixing a polyester polyol having a number average molecular weight of 600 to 5000 and a low molecular compound having active hydrogen if desired and preheating to about 40 to 100 ° C., the ratio of the isocyanate group 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 organic solvent inert to the isocyanate group. If desired, conventional urethanization catalysts such as organotin compounds and tertiary amines may be used. When the production process is carried out in the presence of an organic solvent, it is convenient to determine the amount of the organic solvent used so that the solid content of the final mixture is about 10 to 90% by weight, preferably 20 to 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.

In the present invention, the above-mentioned polyester polyol or polyurethane polyol which is preferably used as a polymer having a group represented by the formula (I) in the molecule preferably has at least two hydroxyl groups at the molecular terminals.

In the present invention, the adhesive can be formed only from a polymer having a group represented by the formula (I) in the molecule. It is preferable that a compound having at least three groups capable of reacting with a hydroxyl group in the polymer is blended with a polymer having a group represented by (I) as a crosslinking agent to form an adhesive.

Examples of the curing agent used here include an organic polyisocyanate, an epoxy resin and a mixture thereof, and an organic polyisonate is 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.

In this way, a polyester adhesive or a polyol carbonate polyol and a diisocyanate, or a chain extender is added thereto to prepare a main agent of an adhesive, and a bridging agent is added thereto to form a polyurethane-based adhesive. It is necessary that the main agent contains a component having the structural unit of the formula (I). This is because an adhesive having a structural unit represented by the formula (I) has a large carbon number of 9 and a side chain, has a low glass transition temperature, and inhibits crystallinity. When used, polyurethane is considered to be obtained from synthetic leather which is excellent in hydrolysis resistance and cold resistance, and which is very flexible and has a good texture. This effect is due to the fact that the component represented by the formula (I) contains 5
It must be contained in an amount of at least 5% by weight, and if 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 in a mixture thereof, or a mixture of these polyols and the formula (I)
It is also possible to use a polyester polyol, a polycarbonate polyol, a polycaprolactone, a polyvalerolactone-based polyol, a polytetramethylene glycol, an ether-based polyol such as polypropylene glycol or polyethylene glycol having no group represented by the following formula. In this case, a mixture obtained by reacting a mixture of these polyols and diisocyanate may be used as a main component, or a mixture obtained by reacting each polyol with diisocyanate may be used as a mixture of two or more kinds.
In any case, the group represented by the formula (I)
It is necessary to have it by weight percent or more.

The adhesive layer in the present invention is 10% in 100% modulus.
There needs to be a ~100kg / cm ^2. If it is less than 10 kg / cm ² , the adhesive strength 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. It should be noted that this 100% modulus increases as the amount of the crosslinking agent increases.

On the other hand, polyurethanes for skin materials include 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. Or a polyurethane obtained by reacting one or more polymer diols with an organic diisocyanate and a chain extender, or a polyurethane obtained from each polyol, an organic diisocyanate and a chain extender may be used. A combination of two or more species may be used. Here, polyester polyol or polycarbonate polyol is ethylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-
The adhesive can be prepared in the same manner as in the case of the above adhesive using a diol such as hexanediol, 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, 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, 1,4-butanediol, 2-methyl-1,3-propanediol, 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.

As described above, a polyurethane obtained from a diol, an organic diisocyanate and a chain extender, which is used in ordinary synthetic leather, can be used as the skin material. Among them, in order to make the material more flexible and excellent in 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 the structural unit of the group represented by the formula (II), for example, 2-methyl-1,3-propanediol, 3
-Methyl-1,5-pentanediol, 2-methyl-1,8-
Octanediol and the like are conceivable. Among them, 2-
Methyl-1,8-octanediol is preferred. Equation (I
The other diol used in combination with the compound capable of forming the group represented by I) 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, with only a straight-chain diol, on the contrary, the crystallinity increases, and the polyurethane tends to be hard. In contrast, the formula (I
It is considered that when a material having the group represented by I) is included, the crystallinity is inhibited, so that a flexible polyurethane as a whole can be obtained. The group represented by the formula (II) is 5% by weight of the polyurethane used as the skin material.
It is desirable to contain the above.

The 100% modulus of the polyurethane used as the skin material is preferably 10 to 200 kg / cm ² . If it is less than 10 kg / cm ² , the resistance to mamou will be poor, and if it is more than 200 kg / cm ² , there is no point in combining with a flexible adhesive layer. This skin material may be used as a laminate of an intermediate layer and a top layer. In this case, the intermediate layer is made of a flexible material having a low 100% modulus, while the polyurethane for the top layer is preferably made of a harder polyurethane having a higher 100% modulus in consideration of abrasion resistance. When used as a laminate of a top layer and an intermediate layer, foaming the intermediate layer makes it more flexible.

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. Resin content in adhesive polyurethane solution is 30 ~ 50% 60 ~
If 150 g / m ^{2 is} applied, an adhesive layer having a thickness of several tens of μm will be formed after drying.

 Thereafter, it is aged at 40-60 ° C for 2-3 days.

Thereafter, the release paper is peeled off, and the gravure roll is surface-finished several times as necessary.

Base fabric is synthetic fiber, for example, polyamide, polyester,
Use of semi-synthetic fibers such as vinylon and polyacrylonitrile, for example, rayon, cupra, acetate, or the like, or natural fibers, such as knitted, woven, nonwoven, or impregnated cloth obtained from, for example, silk, wool, cotton, or hemp. Can be. 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 agent can be performed at all. It may be dyed after being made into synthetic leather.

〔Example〕

 Hereinafter, specific examples will be described.

In the examples, the flexibility was compared by touch and then judged according to the classification.

◎ Very good ○ Good △ Slightly hard × Very hard
% Of the surface (Jangle test condition), the surface stickiness, surface cracks, and peeling of the skin layer that occur when left for 5 to 10 weeks were evaluated according to the following classification.

◎ Very good ○ Good △ Slightly bad × Very bad The relationship between the abbreviations in the table below and the compounds 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 IPDI Isophorone diisocyanate HDI Hexamethylene diisocyanate TDI Tolylene diisocyanate MDI 4,4'-Diphenylmethane diisocyanate TMP (TDI) ₃ Trimethylolpropane / tolylene diisocyanate adduct TMP (HDI) ₃ Trimethylolpropane・ Hexamethylene diisocyanate adduct TMP (IPDI) ₃ trimethylolpropane / isophorone diisocyanate adduct (Example of synthetic leather) Using a knife coater on release paper, dry the polyurethane solution for the skin layer (solid content 20%) to a dry thickness of 25 μm. Will be Applied to, by 3 minutes heat dried at 100 ° C., to form a polyurethane coating. 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 then pressed with 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 sequentially from the polyurethane solution for the top layer and the intermediate layer. Examples 1 to 5 and Comparative Examples 1 to 6 As a main component of the adhesive, a polyurethane comprising an adipic acid and a polyester diol obtained from a predetermined diol and an organic diisocyanate is used. Various synthetic leathers were obtained with the following configuration. In Comparative Example 5, polycaprolactone glycol was used as the polyester diol.

The flexibility and hydrolysis resistance of the obtained synthetic leather were measured, and the results are shown in Table I.

As is clear from Table I, it can be seen that when an adhesive containing a polyurethane composed of a polyester diol containing a group represented by the formula (I) as a main component is used, a soft synthetic leather having a good texture can be obtained. Further, it can be seen that the polyurethane containing this group is extremely excellent in hydrolysis resistance.

Further, no matter how the adhesive contains the group represented by the formula (I), if the 100% modulus of the adhesive is larger than 100 kg / cm ² , a soft leather cannot be expected. Such 100% high modulus adhesives are available when the base material has a structure such as a segmented polyurethane.

Examples 6, 7, 8 and Comparative Example 7 Synthetic leather was obtained in the same manner as in Example 1 using polyurethane composed of polycarbonate diol and organic diisocyanate as a main component of the adhesive layer, and then various performances were evaluated. The results are shown in Table II.

The synthetic leather of Comparative Example 7 in which a polyurethane using hexanediol-based polycarbonate, which has been well known as a representative so far, is used as an adhesive, has good hydrolysis resistance but is inferior in flexibility. On the other hand, it can be seen that the synthetic leather according to the examples has remarkably improved flexibility while maintaining good hydrolysis resistance of the polycarbonate-based polyurethane. Further, the synthetic leather according to the present invention was supple and had a very good feeling by touch.

Examples 9 to 15 and Comparative Examples 8 to 10 The number average molecular weight (MW) of the main component of the adhesive layer was 1,000.
Various synthetic leathers were obtained in the same manner as in Example 1 by using the polyurethanes composed of the various types of high molecular diols and diisocyanates in the configuration shown in Table III. Table III also shows the results of evaluating the flexibility and hydrolysis resistance of the obtained synthetic leather.

As is clear from the table, other high molecular weight diols can be mixed with other general diols if necessary, as long as the group represented by the formula (I) accounts for 5% by weight or more of the main agent in the adhesive. . In this case, since the high molecular weight diol containing the group represented by the formula (I) has excellent hydrolysis resistance, it is desirable to use a composition which does not impair the hydrolysis resistance.

(Effects of the Invention) As described above, according to the present invention, a polyurethane containing a specific structural unit and having a specific physical property value is used as an adhesive layer, and is further combined with a skin layer made of polyurethane. , Good durability and feeling,
Synthetic leather with high flexibility and high commercial value is provided.

Claims (1)

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