JPH06172482A - Thermoplastic polyurethane resin composition and watch belt comprising the same - Google Patents

Abstract

PURPOSE:To obtain the subject composition suitable for watch band, having excellent heat resistance, moldability, processability and bleed resistance by using both a specific polymer diol, a low-molecular diol and an organic diisocyanate. CONSTITUTION:The objective composition comprises (A) a polymer diol containing a hydroxyl group at the end such as a polymer diol obtained by blending (i) a polymer diol having 1,500-3,500 number-average molecular weight obtained from 1,6-hexanediol and a dicarboxylic acid with (ii) a polymer diol having 1,800-5,000 number-average molecular weight obtained from 3-methyl-1,5- pentanediol and a dicarboxylic acid in the molecular ratio of the component (i)/the component (ii) of 7/3-3/7, (B) a low-molecular diol such as ethylene glycol and (C) an organic diisocyanate such as 2,4-tolylene diisocyanate in the molecular ratio of the component A/the component B of 1/0.1-1/10.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermoplastic polyurethane resin composition. More specifically, the present invention relates to a thermoplastic polyurethane resin composition in which a polyester made from 1,6-hexanediol and dicarboxylic acid and 3-methyl-1,5-pentanediol and dicarboxylic acid is used in combination as a polymer diol component.

[0002]

2. Description of the Related Art Conventionally, thermoplastic polyurethane has attracted attention as a substitute material for rubber and plastics because of its many advantages such as high elasticity, excellent abrasion resistance and oil resistance. It is used in large amounts in a wide range of applications as a molding material to which can be applied. Thermoplastic polyurethane is known to be obtained by polymerizing a high-molecular diol such as polyester diol, polyether diol, and polycarbonate diol, a low-molecular diol, and an organic diisocyanate. From the viewpoint of general physical properties and heat resistance, polyester diol is known. A type of thermoplastic polyurethane is preferably used. However,
Since conventional thermoplastic polyurethane has a large temperature dependence of melt flow characteristics and strong adhesiveness, it has poor flowability in the mold compared to other general-purpose thermoplastic resins, and mold release is inferior. However, there is a problem in that the defective molding rate is high. In addition, when molding is performed at a high temperature to improve fluidity, the molding temperature at this time approaches the decomposition temperature of the thermoplastic polyurethane, which causes thermal deterioration, resulting in a significant decrease in the physical properties of the molded product. There is also a method of adding a lubricant to improve the tackiness, release property and productivity of the thermoplastic polyurethane, but since the lubricant is a component lacking compatibility with the thermoplastic polyurethane, it blows on the surface of the molded product. There was a problem (bleeding) that impaired the appearance.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermoplastic polyurethane resin composition which has excellent melt flow characteristics and releasability and has improved bleed.
The inventors of the present invention, as a result of extensive research and study, do not impair the excellent mechanical properties that are characteristic of thermoplastic polyurethane, and have a low molecular weight product on the surface of a molded article, which has been a drawback of conventional thermoplastic polyurethane. The present invention finds a thermoplastic polyurethane resin composition that improves the bleeding phenomenon caused by migration, and simultaneously improves the moldability, which was also a drawback of conventional thermoplastic polyurethanes, and that has good flow characteristics and a fast release cycle. Came to complete.

[0004]

That is, the present invention provides a thermoplastic polyurethane resin composition using a polymer diol (A) having a hydroxyl group at a terminal, a low molecular diol (B), and an organic diisocyanate (C). , (A)
Is a high molecular weight diol (A1) having a number average molecular weight of 1500 to 3500 obtained from 1,6-hexanediol and a dicarboxylic acid, a number average molecular weight obtained from 3-methyl-1,5-pentanediol and a dicarboxylic acid. Is 180
A high molecular weight diol (A2) of 0 to 5000 (A1
) / (A2) in a molar ratio of 7/3 to 3/7 is used, and the molar ratio of (A) / (B) is 1 / 0.1 to 1/10. And a watch band obtained from the thermoplastic polyurethane resin composition.

The contents of the present invention will be further described in detail. Examples of the polymer diol (A) having a hydroxyl group at the terminal in the present invention include polyester diol obtained by polycondensing 1,6-hexanediol and dicarboxylic acid, and 3-methyl-1,5-pentanediol and dicarboxylic acid. And a polyester diol obtained by polycondensation of 1,6-hexanediol polyester diol and 3-methyl-1,
As the dicarboxylic acid for producing the 5-pentanediol-based polyester diol, an aliphatic dicarboxylic acid having 4 to 12 carbon atoms or an aromatic dicarboxylic acid having 8 to 12 carbon atoms is preferable, and specific examples thereof include: Examples include succinic acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid, and terephthalic acid. Of these, adipic acid and azelaic acid are preferable.

The low molecular weight diol (B) in the present invention is preferably a diol having 2 to 10 carbon atoms, such as ethylene glycol, 1,2-propylene glycol and 1,4-
Examples include butanediol, 1,6-hexanediol, diethylene glycol, 3-methyl-1,5-pentanediol, methyloctanediol and 1,9-nonanediol. Of these, 1,4-butanediol and 1,6-hexanediol are preferable.

Polymer diol (A) used in the present invention
Examples of the polyester diol (A1) having a number average molecular weight of 1500 to 3500, preferably 1800 to 3000, obtained from 1,6-hexanediol and dicarboxylic acid, 3-methyl-1,5-pentanediol and dicarboxylic acid And the number average molecular weight obtained from
000, preferably 2000-4500 polyester diol (A2) and (A1) / (A2)
Have a number average molecular weight of 1800 to 4500, and preferably 20 in a molar ratio of 7/3 to 3/7.
00-4000, more preferably 2000-350
The polyester diol (A) having a hydroxyl group at the terminal of 0, particularly preferably 2100 to 2900.

The (A1) / (A2) molar ratio is 3/7.
When it is smaller, the adhesiveness of the resin is large and the releasability during molding is poor. On the other hand, when it is larger than 7/3, the temperature dependence of the melt flow characteristics is large and the improvement effect cannot be obtained. Further, when (A1) having a number average molecular weight of less than 1500 is used, bleeding tends to occur, and when (A2) having a number average molecular weight of less than 1800 is used, the releasability is poor. No effect. Further, the number average molecular weight of (A1) is 3500 and the number average molecular weight of (A2) is 500.
If it exceeds 0, the temperature dependence of the melt flow characteristics is large and excellent moldability cannot be obtained. The use ratio of the high molecular diol (A) and the low molecular diol (B) in the present invention is 1 / 0.1 to 1/1 in terms of the molar ratio of (A) / (B).
The range is 0, preferably 1/1 to 1/10.

Examples of the organic diisocyanate used in the present invention include 2,4-tolylene diisocyanate,
Aromatic diisocyanates such as 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, P-phenylene diisocyanate, tolidine diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, and the like, Hexamethylene diisocyanate, isophorone diisocyanate, bis (isocyanatomethyl) cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate,
And aliphatic or alicyclic diisocyanates such as These diisocyanates may be used alone,
Further, two or more kinds may be mixed and used.

In the present invention, the amount of the organic diisocyanate used is usually 0.95 to 1.10 with respect to 1 mol of the diol component which is the total of (A1), (A2) and (B).
It is preferably within the range of A conventionally known method can be applied as a method for producing a thermoplastic polyurethane using the thermoplastic polyurethane resin composition of the present invention. For example, a predetermined amount of high molecular weight diols (A1) and (A2) and a low molecular weight diol (B) are mixed at a temperature of 60 to 80 ° C, and then an organic diisocyanate heated at a temperature of 45 to 60 ° C is further added and mixed. Then, the reaction is completed by aging at a temperature of 50 to 180 ° C. for 0.5 to 24 hours, and then pulverizing and pelletizing. The watch band of the present invention can be manufactured by injection molding a pelletized thermoplastic polyurethane. The thermoplastic polyurethane of the present invention has many characteristics, but various additives such as an antioxidant, an ultraviolet absorber and a hydrolysis inhibitor can be added depending on the purpose.

[0011]

EFFECT OF THE INVENTION Since the thermoplastic polyurethane obtained by the present invention has excellent heat resistance and molding processability, it can be easily molded by a commonly used injection molding machine, extrusion molding machine, blow molding machine or the like, and released. Molding cycle can be shortened because of good properties. From these facts, it is very useful for reducing the defect rate and improving productivity at the same time. Utilizing hydrolysis resistance and non-bleeding properties, it is widely used in automobile parts, machinery industry parts, hose tubes, films, sports equipment, etc., and is most suitable for watch bands, etc., which are members that come into direct contact with human skin. .

[0012]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Example 1 Polyester diol (A1) having a number average molecular weight of 2200 (hereinafter referred to as PHA) 2200 obtained from 1,6-hexanediol and adipic acid as a polymer diol component, 3 -Methyl-1,5-pentanediol and adipic acid (hereinafter, referred to as PMPA) Mn = 2860 polyester diol (A2) and low-molecular diol component 1,4-butanediol (hereinafter, 1, 4-BD) is heated to a temperature of 75 ° C. and 4,4′-diphenylmethane diisocyanate (hereinafter referred to as MDI) as an organic diisocyanate component is heated to a temperature of 60 ° C. to obtain PHA / PMPA / 1,4.
-BD / MDI was continuously fed to the twin-screw extruder by a metering pump in an amount such that the used molar ratio was 1/1/8 / 10.2. The resulting polyurethane was continuously extruded in the form of a strand into water and then pelletized with a pelletizer to obtain a thermoplastic polyurethane.

Example 2 PHA and M having Mn = 2200 as high molecular diol components
n = 2860 PMPA and a mixture of 1,4-BD as a low molecular diol component heated to a temperature of 75 ° C and MDI as an organic diisocyanate component at a temperature of 60 ° C to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the used molar ratio was 1/1 / 11.6 / 13.8.

Example 3 PHA and M having Mn = 1800 as high molecular diol components
n = 3240 PMPA and a mixture of 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. Example 1 except that the molar ratio used was 1/1 / 8.6 / 10.6
A thermoplastic polyurethane was obtained in the same manner as in.

Example 4 PHA and M having Mn = 2930 as high molecular diol components
n = 2530 PMPA and a mixture of 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the used molar ratio was 1/1/6/8.

Example 5 PHA and M having Mn = 2200 as high molecular diol components
n = 4020 PMPA and a mixture of 1,4-BD as a low-molecular diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the used molar ratio was 0.7 / 0.3 / 6/7.

Example 6 PHA and M having Mn = 2200 as high molecular diol components
n = 3240 PMPA and a mixture of 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio used was 1 / 1.5 / 8.8 / 11.3.

Example 7 A watch band was obtained by injection molding using the thermoplastic polyurethanes obtained in Examples 1 to 6. The moldability of the obtained thermoplastic polyurethane was very good. When these watch bands were immersed in water at room temperature for 2 months and visually evaluated for appearance, no change in appearance was observed.

Comparative Example 1 A polyester diol having Mn = 2900 obtained from 1,4-BD as a polymer diol component and adipic acid (hereinafter referred to as PBA) and 1,4-BD as a low molecular diol component were heated at a temperature of The mixture heated to 75 [deg.] C. and MDI as an organic diisocyanate component were heated to a temperature of 60 [deg.] C., and the molar ratio of PBA / 1,4-BD / MDI used was 1/3.
A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the amount was 5 / 4.6.

Comparative Example 2 Polycaprolactone (hereinafter referred to as PCL) obtained by using ethylene glycol as an initiator as a polymer diol component, a polyester diol of Mn = 2970 and 1,4-BD as a low molecular diol component at a temperature of The same procedure as in Example 1 was repeated except that the mixture heated to 75 ° C. and MDI as an organic diisocyanate component were heated to a temperature of 60 ° C., and the used molar ratio of PCL / 1,4-BD / MDI was 1/4/5. As a result, a thermoplastic polyurethane was obtained.

Comparative Example 3 PHA and M having Mn = 1500 as high molecular diol components
A mixture of PMPA of n = 990 and 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the used molar ratio was 1/1/3/5.

Comparative Example 4 PHA and M having Mn = 3990 as high molecular diol components
n = 5990 PMPA and a mixture of 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component heated to a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio used was 1/1 / 19.2 / 21.2.

Comparative Example 5 PHA and M having Mn = 1010 as high molecular diol components
n = 2530 PMPA and a mixture of 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio used was 1/1 / 5.2 / 7.2.

Comparative Example 6 PHA and M having Mn = 2600 as high molecular diol components
A mixture of PMPA of n = 990 and 1,4-BD as a low molecular weight diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component at a temperature of 60 ° C. to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio used was 1/1 / 5.2 / 7.2.

Comparative Example 7 PHA with Mn = 2600 as a polymer diol component and 1,4-BD as a low molecular diol component were used at a temperature of 75 ° C.
As a mixture with the organic diisocyanate component heated to room temperature
PIA / 1,4-BD / M by heating DI to a temperature of 60 ° C
A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio of DI used was 1 / 4.4 / 5.4.

Comparative Example 8 PMPA having a Mn of 2530 as a polymer diol component and 1,4-BD as a low molecular diol component were used at a temperature of 75.
PMPA / 1,4-BD by heating the mixture heated to 60 ° C and MDI as an organic diisocyanate component to a temperature of 60 ° C.
A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the used molar ratio of / MDI was 1 / 6.5 / 7.5.

Comparative Example 9 PHA and M having Mn = 2200 as high molecular diol components
n = 2860 PMPA and a mixture of 1,4-BD as a low molecular diol component heated to a temperature of 75 ° C and MDI as an organic diisocyanate component at a temperature of 60 ° C to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio used was 1/4 / 22.5 / 27.5.

Comparative Example 10 PHA and M having Mn = 2200 as high molecular diol components
n = 2860 PMPA and a mixture of 1,4-BD as a low molecular diol component heated to a temperature of 75 ° C and MDI as an organic diisocyanate component at a temperature of 60 ° C to obtain PHA / PMPA / 1,4-BD / MDI. A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the molar ratio used was 1 / 0.25 / 4.9 / 6.2.

Comparative Example 11 Obtained from adipic acid and a mixture of 1,6-hexanediol and 3-methyl-1,5-pentanediol used at a molar ratio of 1/1 as a polymer diol component (hereinafter, referred to as P
HMPA) A mixture of a polyester diol having Mn = 2490 and 1,4-BD as a low molecular diol component heated to a temperature of 75 ° C. and MDI as an organic diisocyanate component to a temperature of 60 ° C. to obtain PHMPA / 1,4.
A thermoplastic polyurethane was obtained in the same manner as in Example 1 except that the used molar ratio of BD / MDI was 1/4 / 5.1. The raw materials and composition ratios used in Examples and Comparative Examples are shown in Table 1.
Shown in.

[Test Example] Examples 1 to 6 and Comparative Examples 1 to 1
11, the temperature dependence of the melt flow characteristics of the thermoplastic polyurethane, injection molding processability, bleeding characteristics, heat resistance,
Table 2 shows the results of measurement of hydrolysis resistance and general physical properties.

[Test Method] (1) In the Examples and Comparative Examples, the temperature dependence of the melt flow characteristics of the thermoplastic polyurethane was measured by using a high-performance flow tester CFT-500 manufactured by Shimadzu Corporation according to JIS.
According to the flow test of K7311, constant temperature method (test temperature 1
90, 200, 210 ℃, Die diameter x length = 1mmΦ x 1
mmL, load 10kg), the horizontal axis shows the test temperature,
The melt viscosity is plotted on the vertical axis, and ◎ (less than 5000 P / T), ○ (5000
~ 7500P / T), △ (7501 to 10000P / T)
T) and x (10001 P / T or more) were evaluated in four levels.

(2) The injection molding processability was measured by using an in-line screw type injection molding machine which adopted a control system by a microcomputer, and the heating cylinder temperature was 170 to 22.
5 ℃, injection pressure about 1000kg / cm ² , mold temperature 25 ℃,
120 mm x 120 mm x 2 mm under the condition of molding cycle 80 seconds
X The presence or absence of defective phenomena such as "flow mark", "warp", "sinker", "dimensional accuracy", "bubbles", etc. that occur in the molded product when two molded products are molded continuously The mold releasability of the product was evaluated in four stages (⊚: excellent ○: good Δ: slightly inferior ×: inferior).

(3) Regarding the dimensional accuracy, the volume shrinkage that occurs when the molded product is taken out of the mold and cooled to room temperature at the end of molding as the molding shrinkage ratio was calculated by the following formula.

(4) The bleeding characteristics were as follows: the molded product obtained by injection molding was heated and left for 60 days at 40 ° C. using a Toyo Seiki Seisakusho's Gar type aging tester, and then the surface of the molded product was examined. The presence or absence of defective phenomena such as "bleeding" that occurs in 4 grades is evaluated (◎: excellent ○: good Δ: slightly inferior ×:
Inferior). (5) Heat resistance is 2mm thickness obtained by injection molding
The sheet of No. 3 was punched out into a No. 3 type dumbbell-shaped test piece in accordance with JIS K6301, and after being left to heat for 60 days at 120 ° C using a Gar type aging tester, tensile strength was applied using a Tensilon universal tensile tester UTM type manufactured by Orientec Co., Ltd. Was measured. In the test, the tensile strength of the test piece before heating was similarly measured, and the tensile strength retention rate [the tensile strength after heating / the tensile strength before heating × 100 (%)] was evaluated. .

(6) For hydrolysis resistance, a sheet having a thickness of 2 mm obtained by injection molding was punched into a No. 3 dumbbell-shaped test piece, and the temperature was measured using a thermostat shaker manufactured by Tokyo Rika Kikai Co., Ltd. After soaking in hot water of 85 ° C for 40 days, JIS K6
The tensile strength was measured according to 301. In the test, the tensile strength of the test piece before dipping was measured in the same manner, and the tensile strength retention rate [tensile strength after dipping / tensile strength before dipping × 100 (%)] was evaluated.

(7) As for general physical properties, using a sheet having a thickness of 2 mm obtained by injection molding, JIS K7311 was used.
The hardness (JIS A), tensile strength, elongation, and tear strength were measured according to

[0038]

[Table 1]

[0039]

[Table 2]

Claims (2)

[Claims] 1. A thermoplastic polyurethane resin composition comprising a polymer diol (A) having a hydroxyl group at a terminal, a low molecular diol (B), and an organic diisocyanate (C), wherein (A) is 1,6-hexane. Number average molecular weight obtained from diol and dicarboxylic acid is 1500 to 35
High molecular weight diol (A1) and 3-methyl-1,
A high molecular weight diol (A2) having a number average molecular weight of 1800 to 5000 obtained from 5-pentanediol and a dicarboxylic acid is used, and the molar ratio of (A1) / (A2) is from 7/3 to
A thermoplastic polyurethane resin composition comprising a polymeric diol obtained by mixing at 3/7 and having a molar ratio of (A) / (B) of 1 / 0.1 to 1/10. 2. The method according to claim 1, wherein a resin watch band is the resin composition.