JP2765992B2 - Thermoplastic polyurethane - Google Patents

Description

The present invention relates to certain thermoplastic polyurethanes.

The thermoplastic polyurethane provided by the present invention is excellent not only in mechanical performance and moldability, but also in water resistance, cold resistance and the like, and has a wide range of uses described later.

[Conventional technology]

Conventionally, thermoplastic polyurethane has many features such as high elastic modulus and excellent abrasion resistance and oil resistance, so it has been attracting attention as an alternative material to rubber and plastic, and ordinary plastic molding method is applied It is becoming increasingly used in a wide range of applications as a possible molding material. Thermoplastic polyurethane is produced by mixing and polymerizing a chain extender such as a polymer diol, diisocyanate and 1,4-butanediol.

As the thermoplastic polyurethane, polyester-based polyurethane, polyether-based polyurethane, and polycarbonate-based polyurethane are known, and are used for various applications by utilizing their respective features.

[Problems to be solved by the invention]

It is known that the above-mentioned polyester-based polyurethane has excellent mechanical performance, but is inferior in water resistance.

According to the investigations of the present inventors, polyester-based polyurethane has improved water resistance when an aromatic dicarboxylic acid is used as an acid component of a polyester diol as a constituent component thereof, compared to when an aliphatic dicarboxylic acid is used, On the other hand, it has been found that the cold resistance and the formability are reduced. That is, the polyurethane obtained from the polyester diol containing an aromatic dicarboxylic acid as an acid component, when left under a low-temperature atmosphere such as, for example, −20 ° C., significantly reduces flexibility represented by bending resistance. I do.
In addition, this polyurethane has a very high flow start temperature and melt viscosity, and it is difficult to mold at a temperature lower than the heat resistance.

An object of the present invention is to provide a novel polyester-based polyurethane which is excellent in mechanical performance and moldability, and is also excellent in water resistance and cold resistance.

[Means for solving the problem]

According to the present invention, the above object has the following objects: (a) Number average molecular weight
1,500 to 3,500 polyester diols and (b) a diisocyanate and (c) a chain extender, and the sum of the weights of components (b) and (c) is the sum of components (a), (b) and (c) ) Is in the range of 13-45% of the sum of the weights,
The polyester diol has the following structural units (I) and / or (II) as essential structural units derived from diol, and the following structural units (III) and (IV) as essential structural units derived from dicarboxylic acid. And the ratio of the mole fraction of the structural unit (I) to the mole fraction of the structural unit (II) is in the range of 100: 0 to 50:50, and the mole fraction of the structural unit (III) is The molar fraction ratio of the structural unit (IV) is 80: 20-35:
This is achieved by providing a thermoplastic polyurethane characterized in the range of 65.

(Wherein, n represents an integer of 4 to 12, and Ar represents 6 to 12 carbon atoms.)
Represents a divalent aromatic hydrocarbon group. The thermoplastic polyurethane having the above specified structure of the present invention exhibits a high degree of properties such as excellent mechanical performance, moldability, water resistance, and cold resistance.

It is extremely important that the polyester diol constituting the thermoplastic polyurethane of the present invention has a number average molecular weight in the range of 1,500 to 3,500 determined from the hydroxyl value and the acid value. The number average molecular weight is particularly preferably in the range of 1,800 to 3,000. When the number average molecular weight is less than 1,500, moldability and cold resistance are reduced, and when it exceeds 3,500, mechanical performance and water resistance are reduced.

The polyester diol has the structural units (I) and / or (II) as essential structural units derived from diol, and has the structural units (III) and (IV) as essential structural units derived from dicarboxylic acid. .

As a typical compound giving the structural unit (I), 1,9-
Nonanediol is exemplified, and a typical compound that provides the structural unit (II) is 2-methyl-1,8-octanediol. The higher the proportion of the structural unit (I) and / or (II) in the diol-derived structural unit, the higher the thermoplastic polyurethane exhibiting the above excellent properties. The structural unit (I) and / or (I
The proportion of structural units derived from diol of I) is 30
It is preferably at least 50% by weight, more preferably at least 50% by weight. It is particularly preferred that the structural unit derived from a diol comprises only structural units (I) and / or (II). The ratio of the mole fraction of the structural unit (I) to the mole fraction of the structural unit (II) is in the range of 100: 0 to 50:50. When the mole fraction of the structural unit (II) is larger than the mole fraction of the structural unit (I), the heat resistance and the cold resistance of the thermoplastic polyurethane are inferior. Examples of the polyol used in combination with the production of the polyester diol in the present invention include ethylene glycol, propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 1,6-hexanediol, 1,10-decanediol,
Trimethylolethane, trimethylolpropane and the like. These polyols are used alone or in a mixture of two or more.

Examples of the aliphatic dicarboxylic acid giving the structural unit (III) include adipic acid, azelaic acid, sebacic acid, dodecane diacid, and the like, with adipic acid and azelaic acid being preferred. These aliphatic dicarboxylic acids are used alone or in a mixture of two or more. The divalent aromatic hydrocarbon group having 6 to 12 carbon atoms represented by Ar in the structural unit (IV) is specifically a phenylene group or a naphthylene group.
As the aromatic dicarboxylic acid giving the structural unit (IV),
Terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-
Examples include naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid, and isophthalic acid and terephthalic acid are preferred. These aromatic dicarboxylic acids are used alone or in a mixture of two or more. The ratio of the mole fraction of structural unit (III) to the mole fraction of structural unit (IV) is in the range from 80:20 to 35:65. The molar fraction of the structural unit (III) is
A thermoplastic polyurethane obtained from a polyester diol exceeding 80% based on the sum of the molar fraction of V) does not exhibit the above-mentioned excellent properties in the present invention. When the mole fraction of the structural unit (IV) and the mole fraction of the structural unit (III) are more than 65%, the moldability and cold resistance of the thermoplastic polyurethane deteriorate. .

The polyester diol in the present invention is produced by, for example, a method similar to a known method used in the production of polyethylene terephthalate or polybutylene terephthalate, that is, a transesterification reaction or a direct esterification reaction followed by a melt polycondensation reaction.

The thermoplastic polyurethane of the present invention comprises the sum of the weights of the components (b) and (c), that is, the weight of the hard segment component is 13 to 45 relative to the sum of the weights of the components (a), (b) and (c). It is important to be in the% range. The weight of the hard segment component is preferably in the range of 15 to 40% based on the sum of the weights of components (a), (b) and (c). 13% of the weight of the hard segment components
If the amount is less than 45%, the mechanical performance of the thermoplastic polyurethane becomes poor, and if it exceeds 45%, the change with time of the melt viscosity of the thermoplastic polyurethane becomes large, and the moldability becomes poor. The thermoplastic polyurethane of the present invention preferably has an equivalent ratio (NCO / OH) of the isocyanate group of the component (b) to the hydroxyl group of the component (a) in the range of 1.5 to 5.0. If the equivalent ratio is less than 1.5, the mechanical performance of the thermoplastic polyurethane tends to decrease,
If the ratio exceeds the above range, the molding processability of the thermoplastic polyurethane tends to be poor, and any case is not preferable.

The thermoplastic polyurethane of the present invention is obtained by melt-polymerizing a polyester diol, a diisocyanate, and a chain extender. Examples of the diisocyanate used include aliphatic containing two isocyanate groups in the molecule,
Alicyclic or aromatic diisocyanates, for example
4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, tolylene diisocyanate,
Examples include 1,5-naphthylene diisocyanate, xylylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate. As the diisocyanate, 4,4'-diphenylmethane diisocyanate is particularly preferred. It is also possible to use a small amount of trimethylolpropane or triisocyanate obtained by adding 3 mol of diisocyanate to 1 mol of glycerin. As the chain extender, a conventional chain growing agent in the polyurethane industry, that is, a low molecular weight compound having a molecular weight of 400 or less containing at least two hydrogen atoms capable of reacting with isocyanate can be used, for example, ethylene glycol, propylene glycol, 1,4-butanediol,
Neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, xylylene glycol, 1,4-bis (β-
(Hydroxyethoxy) benzene, bis (β-hydroxyethyl) terephthalate, polyol such as trimethylolpropane, glycerin; ethylenediamine, propylenediamine, xylylenediamine, 4,4′-diaminodiphenylmethane, 3,3′-dichloro-4 Diamines such as 4,4'-diaminodiphenylmethane, isophoronediamine, piperazine, phenylenediamine, tolylenediamine;
Hydrazine; hydrazide such as adipic dihydrazide and isophthalic dihydrazide; As a chain extender, 1,4-butanediol or 1,4-bis (β-
Most preferably, (hydroxyethoxy) benzene is used. These compounds are used alone or in combination of two or more. As the polymerization conditions, those employed in known urethane production reactions are applied, but the polymerization temperature is 190 to 2
Preferably, a temperature in the range of 40 ° C is employed. Polymerization temperature
By maintaining the temperature at 190 ° C or higher, a thermoplastic polyurethane having good moldability can be obtained, and the polymerization temperature can be increased to 240 ° C.
By keeping the temperature at or below ℃, a thermoplastic polyurethane having increased heat resistance can be obtained. As the polymerization method, it is particularly preferable to employ a continuous melt polymerization method using a multi-screw extruder.

The thermoplastic polyurethane of the present invention obtained as described above preferably has a logarithmic viscosity in the range of 0.4 to 1.8 dl / g, more preferably 0.5 to 1.5 dl / g.

The thermoplastic polyurethane of the present invention can be used by mixing additives such as a stabilizer, a filler, a reinforcing agent, an antistatic agent and a pigment according to the purpose of use.

The thermoplastic polyurethane of the present invention has excellent moldability and can be easily molded by a commonly used injection molding machine, extrusion molding machine, blow molding machine, calender or the like.
Since the thermoplastic polyurethane of the present invention has excellent mechanical performance, water resistance and cold resistance, sheets, films, rolls, gears, solid tires, snow tires, snow chains, belts, watch bands, hoses, tubes, packing materials, Anti-vibration materials, shoe soles, sports shoes, and other laminated product materials, machine parts, automobile parts,
Used for sporting goods, elastic fibers, etc. Further, the thermoplastic polyurethane of the present invention is dissolved in a solvent and artificial leather,
It is also used as a coating agent, a fiber treatment agent, an adhesive, a binder, a filler, and the like.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

In the reference examples, the number average molecular weight was determined according to the following method. In the examples, the cold resistance, molding processability, water resistance, mechanical performance, and cutting property of the thermoplastic polyurethane were evaluated according to the following methods. The hard segment content of the thermoplastic polyurethane means the weight percentage of the segment based on the diisocyanate and the chain extender in the thermoplastic polyurethane.

(1) Number average molecular weight: determined from the hydroxyl value and acid value of the polyester diol.

(2) Cold resistance: A test piece prepared from a thermoplastic polyurethane film having a thickness of 100 μm was subjected to Tα (E ″) by temperature dispersion using a dynamic viscoelasticity measuring device (DVE Rheospectral, manufactured by Rheology Co., Ltd.). , Peak temperature of 11 Hz), thereby evaluating cold resistance.

(3) Moldability: Evaluated by the flow start temperature and melt viscosity of the thermoplastic polyurethane. The flow start temperature was measured by using a Koka type flow tester (Kokazu Co., Ltd., Koka type flow tester CFT-500 type) by a temperature raising method (Hold 150 ° C x 36).
0 seconds, heating rate 5 ° C / min, die diameter x length = 1.0mmφ x 10
mm, load 100 kg). For the melting year, the same equipment was used and the constant temperature method (200 ° C, die diameter x length = 1.0
mmφ × 10mm, load 50kg).

(4) Water resistance: A 100 μm-thick film obtained by compression-molding thermoplastic polyurethane pellets was placed in hot water at 100 ° C. and subjected to a hydrolysis promotion test for 2 weeks. Water resistance was evaluated by the tensile strength retention.

(5) Mechanical performance: A 100 μm-thick film obtained by compression-molding a thermoplastic polyurethane pellet was punched out with a No. 3 dumbbell, and the breaking strength and breaking elongation were measured at a tensile speed of 30 cm / min. These were used to evaluate the mechanical performance.

(6) Cutting properties: Evaluating the ease of cutting when the strand-shaped thermoplastic polyurethane is cut by a pelletizer into a pellet at the time of polymerization. The middle is indicated by △.

Reference Example 1 Production of Polyester Diol 2,080 g of a mixture of 1,9-nonanediol and 2-methyl-1,8-octanediol (molar ratio = 95: 5) and a mixture of adipic acid and isophthalic acid (molar ratio = 50) : 50) 1,560g
(Molar ratio of diol and adipic acid = 1.3: 1.0) was charged into the reactor, and while condensing water from the system while gradually increasing the reaction temperature from 160 ° C to 220 ° C while passing nitrogen gas into the system under normal pressure. Evaporation was carried out to carry out an esterification reaction. When the acid value of the polyester became 0.5 or less, the degree of vacuum was gradually increased by a vacuum pump to complete the reaction. The polyester diol thus obtained had a hydroxyl value of 55.8, an acid value of 0.3, and a number average molecular weight of 2,000.

Reference Examples 2 to 11 Production of Polyester Diol An esterification reaction was carried out in the same manner as in Reference Example 1 except that a dicarboxylic acid giving a dicarboxylic acid component shown in Table 1 and a diol giving a diol component were used. The diol was obtained.

For the polyester diols obtained in Reference Examples 1 to 11, the diol component and its ratio, a dicarboxylic acid component,
Table 1 summarizes the number average molecular weight. In Table 1, the diol component and the dicarboxylic acid component are represented by diols and dicarboxylic acids indicated by the following abbreviations, which provide these components.

MOD: 2-methyl-1,8-octanediol ND: 1,9-nonanediol HD: 1,6-hexanediol AD: Adipine plan AZA: Azelaine plan SA: Sebacic acid IPA: Isophthalic acid TA: Terephthalic acid Example 1 Production and Performance Evaluation of Polyurethane A mixture of polyester diol (A) and 1,4-butanediol (hereinafter abbreviated as BD) at a molar ratio of 1: 2 was heated to 30 ° C, and heated to 50 ° C. 4,4 '
-Diphenylmethane diisocyanate (hereinafter referred to as MD
I) for polyester diol (A) vs. MDI vs. BD
At a molar ratio of 1: 3: 2 to a twin-screw extruder rotating in the same direction by a metering pump to continuously carry out a continuous melt polymerization reaction. When the inside of the twin-screw extruder was divided into three zones, a front portion, an intermediate portion and a rear portion, the highest temperature (polymerization temperature) of the intermediate portion was set to 220 ° C. The resulting polyurethane was continuously extruded into water in the form of a strand, and then cut with a pelletizer to form a pellet. Further, a pellet was formed by hot pressing to obtain a sheet and a film, and the water resistance, the cold resistance, and the mechanical performance of these were evaluated. The formability was also evaluated using a pellet.
Table 2 shows the evaluation results.

The obtained polyurethane had good moldability, water resistance, cold resistance, mechanical performance, and cutting properties.

Example 2 Production and Performance Evaluation of Polyurethane In Example 1, polyester diol (A) vs. MDI
The reaction and operation were carried out in the same manner except for the charging, except that the molar ratio of BD to BD was 1: 2: 1. A pellet of polyurethane was obtained, which was formed into sheets and films in the same manner, and various performances were evaluated. did. Table 2 shows the evaluation results.

The obtained polyurethane had good moldability, water resistance, cold resistance, mechanical performance, and cutting properties.

Comparative Example 1 Production and Performance Evaluation of Polyurethane Polyester Diol (A) vs. MDI in Example 1
A polyurethane pellet was obtained by performing the same reaction and operation except that the molar ratio of BD to BD was 1: 5.5: 4.5, except for the charging, and then formed into sheets and films in the same manner to evaluate various performances. did. Table 2 shows the evaluation results.

The obtained polyurethane had remarkably poor moldability and cold resistance.

Comparative Example 2 Production and Performance Evaluation of Polyurethane Polyester Diol (A) vs. MDI in Example 1
The reaction and operation were carried out in the same manner except for the charging, except that the molar ratio of BD to BD was 1: 1.1: 0.1. A pellet of polyurethane was obtained, which was formed into sheets and films in the same manner, and various performances were evaluated. did. Table 2 shows the evaluation results.

The resulting polyurethane had remarkably poor mechanical performance.

Examples 3 to 8 and Comparative Examples 3 to 7 Production and Performance Evaluation of Polyurethane In Example 1, polyester diol shown in Table 2 was used in place of polyester diol (A), and polyester diol and MDI were used in a molar ratio shown in Table 2. The reaction and operation were carried out in the same manner except for the preparation of BD and BD to obtain a pellet of polyurethane, which was similarly formed into a sheet and a film, and various performances were evaluated. Table 2 shows the evaluation results.

The polyurethanes obtained in the examples had good moldability, water resistance, cold resistance, mechanical performance, and cutting properties.

The polyurethane obtained by the comparative example was not good in all of moldability, water resistance, cold resistance, mechanical performance and cutting properties. The polyurethane obtained in Comparative Example 7 was particularly poor in cutting properties.

Example 9 Production and Performance Evaluation of Polyurethane In Example 1, a mixture of BD and 1,4-bis (β-hydroxyethoxy) benzene (hereinafter abbreviated as BHEB) in a molar ratio of 2: 1 was used instead of BD. MDI was used and the molar ratio of polyester diol (A) to MDI to BD to BHEB was 1
The reaction and the operation were carried out in the same manner except for the charging in an amount of 2.5: 1.0: 0.5 to obtain a pellet of polyurethane, which was formed into a sheet and a film in the same manner, and various performances were evaluated. Table 2 shows the evaluation results.

The obtained polyurethane had good moldability, water resistance, cold resistance, mechanical performance, and cutting properties.

[Effects of the Invention] As is clear from Table 2, the thermoplastic polyurethane provided by the present invention is excellent in all of moldability, water resistance, cold resistance, mechanical performance, and cutting properties.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08G 18/42 C08G 63/16

Claims (1)

(57) [Claims] 1. A polyester diol having (a) a number average molecular weight of 1,500 to 3,500, (b) diisocyanate and (c)
A chain extender and the sum of the weights of components (b) and (c) is in the range of 13-45% relative to the sum of the weights of components (a), (b) and (c); The polyester diol has the following structural units (I) and / or (II) as essential structural units derived from diol, and the following structural units (III) and (IV) as essential structural units derived from dicarboxylic acid. And the ratio of the mole fraction of the structural unit (I) to the mole fraction of the structural unit (II) is in the range of 100: 0 to 50:50, and the mole fraction of the structural unit (III) is Structural unit (I
A thermoplastic polyurethane, characterized in that the molar fraction ratio of V) is in the range from 80:20 to 35:65. _{(I): - OCH 2 9} O- (In the formula, n represents an integer of 4 to 12, and Ar represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.)