JP3289807B2 - Polyurethane elastomer and elastic fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane elastomer having excellent elastic recovery and heat resistance.
Specifically, it has a branched (cross-linked) structure, and 0.1 to 50% of all urethane bonds are urethane bonds composed of an aromatic hydroxyl group and an aromatic isocyanate group. The present invention relates to a polyurethane elastomer having excellent properties and elastic fibers obtained therefrom.

[0002]

2. Description of the Related Art Conventionally, in the production of a polyurethane elastic body, particularly in the production of a polyurethane elastic fiber, a polymer polyol has been used.
, Organic polyisocyanates and low molecular weight polyols are often used, but the elastic recovery and heat resistance of polyurethanes produced therefrom are not always satisfactory. Especially in the field of elastic fibers, their weakness has forced their application to be restricted.

[0003] For this reason, attempts to obtain polyurethane having excellent heat resistance and elastic recovery properties have been made, for example, in Japanese Patent Publication Nos. 63-53287, 63-53288, and JP-A-3-213515. However, its performance has not been satisfactory. In other words, these attempts aim at improving performance by cross-linking consisting of allophanate bonds and burette bonds, but the heat resistance of these bonds is insufficient, and the heat resistance of the polyurethane containing these bonds is also sufficient. It cannot be said that.

On the other hand, the rubber crosslinked by vulcanization or the like is excellent in heat resistance and elastic recovery because of its high heat-resistant chemical bond cross-linking, which is different from polyurethane elastic material. However, it is very difficult to mold such chemically crosslinked polymers, especially to elastic fibers.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polyurethane having high heat resistance and elastic recovery comparable to that of a chemically crosslinked rubber from a high molecular weight polyol, an organic polyisocyanate or a low molecular weight polyol. An object of the present invention is to provide an elastomer and an elastic fiber obtained therefrom.

[0006]

That is, the present invention relates to a polyurethane elastomer comprising a high molecular weight polyol, an organic polyisocyanate, and a low molecular weight polyol, which has a branched structure and is composed entirely of urethane. Out of the join
The present invention relates to a polyurethane elastomer characterized in that 0.1 to 50% is a urethane bond composed of an aromatic hydroxyl group and an aromatic isocyanate group, and an elastic fiber obtained therefrom.

The polymer polyols used in the present invention include polyether polyols represented by polytetramethylene ether glycol, polyester polyols represented by polyethylene adipate, and polycaprolactone polyols. Polyester carbonate polycarbonate exemplified by a reaction product of a polyester glycol such as polycaprolactone and an alkylene carbonate, and the like.
And ethylene carbonate with polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol and neopentyl glycol, and then the resulting reaction mixture is mixed with adipic acid and azelaic acid. Acid, a product reacted with an organic dicarboxylic acid such as sebacic acid, and 1,
4-butanediol, 1,6-hexanediol, 2,
A polyhydroxyl compound such as 2-dimethyl-1,3-propanediol or 1,8-octanediol;
Examples thereof include polycarbonates obtained by transesterification with aryl carbonates, for example, diphenyl carbonates. These may be used alone or in combination of two or more.

The organic diisocyanate includes:
4,4'-diphenylmethane diisocyanate, 1,5
-Naphthalene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate,
Aromatic diisocyanates such as 2,6-tolylene diisocyanate, hexamethylene diisocyanate, 1,4-
Aliphatic diisocyanates such as cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate. These may be used singly or as a mixture of two or more, but 0.1 to 50% of the total urethane bonds of the polyurethane obtained by using these are aromatic hydroxyl groups and aromatic hydroxyl groups. It must be a urethane bond consisting of an isocyanate group.

As the low molecular weight polyol, a compound represented by the formula 1 can be used.

[0010]

Embedded image (In the formula 1, Ar is selected from a monocyclic aromatic group having 3 or more valences, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bonding member. Wherein the aromatic group includes a heterocyclic aromatic group,
A substituent such as an alkyl group, an alkoxy group, or a halogen group may be attached. X ₁ and X ₂ may be the same or different, and include a direct bond, -O-, -S-, -C
OO-, -OCO-, -OCOO-, -CO-, etc. Z ₁ and Z ₂ may be the same or different, and —O—, —S—, —COO—, —OCO—, —O
Represents a bonding member such as COO- and -CO-. Y ₁ , Y ₂ , Y
₃ and Y ₄ may be the same or different and represent an alkylene group having 1 to 6 carbon atoms. l and m may be the same or different and represent an integer of 0 to 3. R represents a hydroxyl group directly bonded to an aromatic ring. a represents an integer of 1 or more. )

Specific examples of compounds include 2,5-
Bis (2-hydroxyethoxycarbonyl) hydroquinone, 3,5-bis (2-hydroxyethoxycarbonyl) phenol, 4,4′-bis (2-hydroxyethoxy) -2,2′-dihydroxy-diphenylmethane and the like. Other examples include 2- (4-hydroxyphenyl) -1,4-butanediol and the like.

These compounds include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6
-Hexanediol, hydroxyethylhydroquinone, cyclohexanedimethanol, bis (2-hydroxyethyl) terephthalate, bis (2-hydroxyethyl) isophthalate, bis (2-hydroxyethyl) phthalate, and o, o'-dihydroxy Diphenylmethane, o, p'-dihydroxydiphenylmethane, p,
ethylene oxide, propylene oxide of p'-dihydroxydiphenylmethane, and mixtures thereof,
It may be used in combination with an adduct such as butylene oxide. However, it is necessary that 0.1 to 50% of all the urethane bonds of the polyurethane obtained by using these are urethane bonds including an aromatic hydroxyl group and an aromatic isocyanate group.

The ratio between the high molecular weight polyol and the low molecular weight polyol in the present invention can be variously changed depending on the molecular weight of each and the desired physical properties of the polyurethane. Further, the number of isocyanate groups (NCO / OH) of the organic polyisocyanate is 0.80 with respect to the total number of hydroxyl groups (including aromatic hydroxyl groups) of both.
Is preferably in the range of 0.95 to 1.25.
More preferably, it is 1.15. If this ratio is too small, the branched structure becomes insufficient and the heat resistance and elastic recovery are unfavorably reduced.If it is too large, the melt viscosity is small, the solidification rate is low, and the surface adhesiveness is large,
It is not preferable because productivity is reduced.

In the present invention, since a low molecular polyol having three or more functional groups as shown in Chemical formula 1 is used, the obtained polyurethane elastomer has a structure in which hard segment portions are crosslinked. Generally, polyurethane elastomers constrain the soft segments by the cohesive force of hydrogen bonds of the hard segments and exhibit rubber-like properties.However, if the cohesive force of the hard segments is a crosslink by a stronger chemical bond, elastic The recoverability and heat resistance are improved. In the present invention, the crosslinking point is mainly a urethane bond, and this bond has higher heat resistance than the allophanate bond or the burette bond. As a result, the polyurethane elastomer obtained by the present invention also has higher heat resistance.

The polyurethane elastomer of the present invention has a crosslink point by a urethane bond in the hard segment portion, and the crosslink point bond is desirably a urethane bond composed of an aromatic hydroxyl group and an aromatic isocyanate group from the viewpoint of moldability. .

Further, in the polyurethane elastomer of the present invention, it is preferable that 0.1 to 50% of all the urethane bonds are urethane bonds composed of an aromatic hydroxyl group and an aromatic isocyanate group. If this is too small, sufficient elastic recovery and heat resistance cannot be obtained. On the other hand, if it is too large, the moldability becomes poor, which is not preferable.

The polyurethane elastomer of the present invention can be produced by a known urethanization technique such as a melting method and a solution method, but is preferably produced by a melting method in consideration of cost, working environment and the like. For example, a compound of a high molecular polyol and a low molecular polyol is added in an amount of about
After preheating to 00 ° C., the organic polyisocyanate is used in such an amount that the number of isocyanate groups of the organic polyisocyanate is 0.95 to 1.15 with respect to the total number of hydroxyl groups (including aromatic hydroxyl groups) of these mixtures. In addition, after stirring vigorously for a short time, the polyurethane is obtained by leaving the mixture at about 50 to 180 ° C under nitrogen. Further, a method of obtaining a polyurethane via a urethane prepolymer can also be used. If necessary, other trifunctional components such as triol and triisocyanate may be used in combination.

In the production of polyurethane, a catalyst or a catalyst generally used in the production of polyurethane is used.
Activators, defoamers, lubricants, UV absorbers, stabilizers such as anti-yellowing agents, pigments, antistatic agents, surface treatment agents, flame retardants, fungicides, reinforcing agents as required Can be used.

The polyurethane elastomer of the present invention can be widely used for resins, molded products, films, elastic fibers and the like.
An elastic fiber having elastic recovery properties can be obtained. The elastic fiber of the present invention can be produced by a spinning method such as melt spinning, dry spinning, and wet spinning. However, it is preferable to perform melt spinning from the viewpoint of cost, fiber homogeneity, and the like.

The spinning apparatus and spinning conditions used for melt-spinning the polyurethane elastomer of the present invention may vary depending on the content of the polyurethane, the desired fiber thickness, the polymerization method, and the like. The polymer is fed to an extrusion spinning apparatus, and the spinning temperature is from 180 to 240.
The spinning is preferably performed at a temperature of 1000 ° C. and a spinning speed of 1000 m / min or less, particularly 600 m / min or less. The apparent draft rate is preferably 50 or more, and more preferably 100 or more. Further, the spinning tension when the spun yarn is wound on a bobbin by a winder is 0.1 g / d or less, preferably 0.05 g / d or less.

The wound yarn is hardened under low humidity.
It is preferable to perform a heat treatment near the glass transition temperature of the hard segment to sufficiently advance the phase separation between the hard segment and the soft segment. In general, polyurethane elastic fibers having a thickness of about 5 to 100 denier // filament can be obtained by these methods, but the polyurethane elastic fibers used in the present invention have a denier in the range of 15 to 100. Is suitable, and preferably 40 to 80. These elastic fibers are used in the form of a covering yarn or a bare yarn.

[0022]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Parts in the examples are parts by weight. Further, in the following examples, logarithmic viscosity, heat resistance, and elastic recovery were measured by the following methods.

<< Preparation of Evaluation Sample >> Polyurethane polymer
Was formed into a film at 220 ° C. using a heat press machine. The heat treatment was performed at 120 ° C. for 16 hours under nitrogen.

<< Measurement of Logarithmic Viscosity >> A molded film polymer (0.0750 g) was treated with 0.05N-dibutylamine /
Dissolved in 25 ml of N, N-dimethylacetamide solvent,
10 ml of this polymer solution was taken in an Ostwald viscometer, and the number of seconds dropped was measured in a thermostat at 30 ° C., and the logarithmic viscosity (η _inh ) was obtained from the following equation. η _inh = {ln (t / t ₀ )} / C t: seconds of falling polymer solution (seconds) t ₀ : seconds of falling solvent (seconds) C: concentration of polymer solution (g / dl) or more Was measured for the logarithmic viscosity of the film.

<< Measurement of heat resistance >> Sample (about 0.1 mm thick)
Film) at 160 ° C (dry heat) under 100% elongation.
The sample was heated for 1 minute, cooled and then relaxed, and the sample length was measured. Heat resistance (%) = {(length after heating-sample length) / sample length}
× 100 Since a polyurethane elastic body having excellent heat resistance is unlikely to undergo permanent deformation due to heating under elongation, the heat resistance defined by the above equation is a small value.

<< Measurement of Elasticity Recovery >> Sample (about 0.1
The film was relaxed after elongating it by 300%, and the stress at the time of elongation at 150% when the film was elongated again by 300% was measured. Elastic recovery rate (%) = (Stress at second 150% elongation /
The stress at the time of the first 150% elongation) × 100 Since the polyurethane elastic body having excellent elastic recovery properties is hardly damaged by elongation, the elastic recovery rate defined by the above equation is a large value.

Examples 1, 2- 100 parts of polybutylene adipate (abbreviated as PBA) having hydroxyl groups at both ends and having a number average molecular weight of 2000, 2,5-bis (2-hydroxyethoxycarbonyl) hydroquinone (abbreviated as compound 1) ) 1.43 parts, bis (2-hydroxyethyl) terephthalate (abbreviated as BHET) 24.1
3 parts and 41.1 parts of diphenylmethane diisocyanate (abbreviated as MDI) (NCO / OH = 1.06) were vigorously stirred at room temperature under nitrogen for about 1 minute, and then transferred to a Teflon bat, and the mixture was stirred under nitrogen stream for 180 minutes. Polymerization was performed at 30 ° C for 30 minutes. A film melt-molded with a heat press was used in Example 1, and a film heat-treated at 120 ° C. for 16 hours in a nitrogen stream was used as Example 2 for measurement.

Example 3 100 parts of PBA, 2.86 parts of Compound 1, 8.1 parts of 1,4-butanediol (abbreviated as BD), MDI 42.
The same experiment as in Example 1 was performed except that polymerization was performed using 4 parts (NCO / OH = 1.06) (only the film after heat treatment).

Example 4 100 parts of PBA, 3,5-bis (2-hydroxyethoxycarbonyl) phenol (abbreviated as Compound 2) 2.7
Parts, BHET 22.86 parts, MDI 41.1 parts (N
The same experiment as in Example 1 was performed except that the polymerization was performed using (CO / OH = 1.06) (only the film after the heat treatment).

Comparative Example 1 100 parts of PBA, 25.4 parts of BHET, MDI 3
The same experiment as in Example 1 was performed except that polymerization was performed using 9.75 parts (NCO / OH = 1.06) (only the film after the heat treatment).

Comparative Example 2 100 parts of PBA, 1,3,5-tris (2-hydroxyethoxycarbonyl) benzene (abbreviated as compound 3)
3.42 parts, BHET 22.86 parts, MDI 41.1
The same polymerization as in Example 1 was carried out using parts (NCO / OH = 1.06). However, in the late stage of polymerization, gelation occurs,
Handling became difficult. This gelled polymer could not be melt molded into a film by a heat press machine. Table 1 shows the results of each example.

[0032]

[Table 1] * Ratio of urethane bonds composed of aromatic hydroxyl groups and aromatic isocyanate groups to all urethane bonds.

The polymers of Example 4 and Comparative Example 1 were each melt-spun to obtain 40 denier / 4 filament elastic yarn. The heat resistance and elastic recovery of the yarn after the treatment at 120 ° C. for 16 hours were measured. The measurement of heat resistance and elastic recovery was performed according to the measurement method using a film. Table 2 shows the results of each example.

[0034]

[Table 2]

[0035]

According to the present invention, a polyurethane elastomer comprising a high molecular weight oleol, an organic polyisocyanate, and a low molecular weight polyol has a branched structure and 0.1 to 50% of all urethane bonds. If% is a urethane bond composed of an aromatic hydroxyl group and an aromatic isocyanate group, a polyurethane elastomer excellent in heat resistance and elastic recovery can be obtained, and a polyurethane elastic fiber excellent in heat resistance and elastic recovery can be obtained.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 18/00-18/87 D01F 6/70

Claims (2)

(57) [Claims] 1. A polyurethane elastomer comprising a high molecular weight polyol, an organic polyisocyanate and a low molecular weight polyol, having a branched structure and having 0.1 to 50% of all urethane bonds. % Is a urethane bond comprising an aromatic hydroxyl group and an aromatic isocyanate group. 2. An elastic fiber made from the polyurethane elastomer of claim 1.