JPH07138339A - Polyurethane - Google Patents

Abstract

PURPOSE:To obtain a polyurethane which hardly increases its melt viscosity during stay in a molding machine, gives a molding free from fisheyes, and is excellent in moldability by reacting a specific high-molecular diol, a specific chain extender, and a specific org. diisocyanate using a specific catalyst. CONSTITUTION:This polyurethane is produced by reacting a high-molecular diol having a mol.wt. of 1,000-5,000 (e.g. a polyester diol obtd. from 1,4- butanediol and adipic acid), an org. diisocyanate (e.g. 4,4'-diphenylmethane diisocyanate), and a chain extender comprising 35-90mol% 1,4-butanediol and 65-10mol% bis(beta-hydroxyethoxy)benzene in the presence of a urethane-forming tin catalyst (e.g. dibutyltin diacetate) in an amt. of Sn of 0.5-15ppm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the increase in melt viscosity and the generation of fish eyes due to retention during molding.
The present invention relates to polyurethane having excellent moldability.

[0002]

2. Description of the Related Art Polyurethanes, particularly polyurethanes having a high hardness, are apt to have a problem that melt viscosity increases due to retention in a molding machine during molding and fish eyes are generated. As a countermeasure against this, addition of a plasticizer has been carried out, but although some improvement has been recognized, it has not been a fundamental solution.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyurethane having excellent moldability in which increase in melt viscosity due to retention during molding and generation of fish eyes are suppressed.

[0004]

According to the present invention, the above object is a polyurethane obtained by polymerizing a polymeric diol, an organic diisocyanate and a chain extender, wherein the polymeric diol has a molecular weight of 1,000. ˜5000, the chain extender consists of 1,4-butanediol (BD) and bis (β-hydroxyethoxy) benzene (BHEB), and the molar ratio of BD to BHEB is 35/65 BD / BHEB. It is achieved by providing a polyurethane characterized by being in the range of 90 to 90/10 and containing a tin-based urethane-forming catalyst in an amount of 0.5 to 15 ppm as a tin atom.

The polymeric diol used in the present invention has a molecular weight of 1 having hydroxyl groups at both ends of the main chain of the molecule.
The polymer may be any polymer of 000 to 5000, and examples thereof include polyester diol, polycarbonate diol, polyester polycarbonate diol, and the like. The high molecular weight diol has a molecular weight (number average molecular weight) of 10
When it is less than 00, a polyurethane excellent in moldability, heat resistance and cold resistance cannot be obtained, and when it exceeds 5,000, a polyurethane having sufficient strength cannot be obtained. The molecular weight is preferably 1500-4500,
More preferably, it is 2000-3500.

The polyurethane of the present invention must contain a tin-based urethane-forming catalyst (hereinafter sometimes referred to as "tin catalyst") in an amount of 0.5 to 15 ppm as a tin atom. Polyurethane having a tin catalyst content of less than 0.5 ppm in terms of tin atom causes a remarkable decrease in molecular weight after molding, resulting in poor physical properties of the obtained molded product. On the other hand, a polyurethane having a tin catalyst content of more than 15 ppm in terms of tin atom has insufficient heat resistance and hydrolysis resistance.

As the method of incorporating the tin catalyst into the polyurethane, a method of adding the tin catalyst during the production of the polymer diol, a method of adding the tin catalyst during the polymerization of the polyurethane, etc. are adopted. Examples of the tin catalyst used in the present invention include tin octylate, monomethyltin mercaptoacetate, monobutyltin triacetate, monobutyltin monooctylate, monobutyltin monoacetate, monobutyltin maleate, and benzyl monobutyltin maleate. Salt, monooctyl tin maleate, monooctyl tin thiodipropionate, monooctyl tin tris (isooctyl thioglycolate), monophenyl tin triacetate, dimethyl tin maleate, dimethyl tin bis (ethylene glycol mono Thioglycolate), dimethyltin bis (mercaptoacetic acid) salt, dimethyltin bis (3-mercaptopropionic acid) salt, dimethyltin bis (isooctyl mercaptoacetate), dibutyls Diacetate, dibutyltin dioctate, dibutyltin distearate, dibutyltin dilaurate, dibutyltin maleate, dibutyltin maleate polymer, dibutyltin maleate ester salt, dibutyltin bis (mercaptoacetic acid), dibutyltin bis (mercaptoacetic acid alkyl ester) salt, Dibutyltin bis (3-mercaptopropionic acid alkoxybutyl ester) salt, dibutyltin bisoctylthioglycol ester salt, dibutyltin (3-mercaptopropionic acid) salt, dioctyltin maleate, dioctyltin maleate, dioctyltin maleate Polymer, dioctyl tin dilaurate, dioctyl tin bis (isooctyl mercaptoacetate), dioctyl tin bis (isooctyl Oh glycolic acid ester), dioctyltin bis (3-mercaptopropionate) can be exemplified salts. Among the above tin catalysts, dialkyltin diacylates such as dibutyltin diacetate and dibutyltin dilaurate; dialkyltin bismercaptocarboxylic acid ester salts such as dibutyltin bis (3-mercaptopropionic acid ethoxybutyl ester) salts are preferable.

Titanium-based catalysts are known as catalysts for accelerating the urethanization reaction. However, with polyurethanes containing titanium-based catalysts, the resulting molded products have poor hydrolysis resistance and extrusion molding. When the melt residence time becomes long during molding such as, the physical properties of the obtained molded product are significantly deteriorated. Therefore, it is desirable that the titanium-based catalyst used during the production of the polymer diol for the purpose of promoting the esterification reaction is deactivated before the production of the polyurethane. As the deactivating method, a method of deactivating the polymer diol by bringing it into contact with water, a method of deactivating the compound by adding a phosphorus compound to the polymer diol, or the like can be adopted.

The polyester diol which can be used as the polymer diol in the present invention is composed of a dicarboxylic acid component and a diol component. The dicarboxylic acid is preferably an aliphatic dicarboxylic acid having 5 to 12 carbon atoms. Examples of the aliphatic dicarboxylic acid include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and the like. Terephthalic acid,
Aromatic dicarboxylic acids such as isophthalic acid may be used together. Examples of the diol include ethylene glycol, 1,4-butanediol, 2-methyl-
1,3-propanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, etc. Is mentioned. The method for producing the polyester diol is not particularly limited, and for example,
A known production method by an esterification reaction or a transesterification reaction is adopted by using a diol, a dicarboxylic acid or an esterified product thereof as a raw material.

The organic diisocyanate used in the present invention may be one commonly used as a raw material for producing polyurethane, and examples thereof include 4,4'-diphenylmethane diisocyanate and p-phenylene diisocyanate. , Toluylene diisocyanate, 1,5-naphthylene diisocyanate and other aromatic diisocyanates; Hexamethylene diisocyanate and other aliphatic diisocyanates; 4,4'-Dicyclohexylmethane diisocyanate and other alicyclic systems An organic diisocyanate having a molecular weight of 500 or less, such as diisocyanate, may be mentioned. Among these, 4,4'-diphenylmethane diisocyanate is preferable.

In the present invention, as the chain extender, 1,
It is necessary to use 4-butanediol (BD) and bis (β-hydroxyethoxy) benzene (BHEB) in a BD / BHEB molar ratio of 35/65 to 90/10. When the ratio of BD is less than 35 mol with respect to 65 mol of BHEB or exceeds 90 mol with respect to 10 mol of BHEB, a polyurethane having excellent moldability cannot be obtained. The chain extender is preferably composed of BD and BHEB only, but other chain extenders (diols other than BD and BHEB having a molecular weight of 400 or less) may be additionally used as long as the amount is small.

As a method for polymerizing a polymer diol, an organic diisocyanate and a chain extender to produce polyurethane, a known urethanization reaction technique can be adopted. Among them, it is preferable to carry out melt polymerization in the substantial absence of a solvent, and particularly preferable is a continuous melt polymerization method using a multi-screw extruder. Generally, the polyurethane obtained by continuous melt polymerization is considerably superior in strength to the polyurethane obtained by solid phase polymerization at 80 to 130 ° C. The melt polymerization temperature is not particularly limited, but is preferably 180 ° C. or higher and 260 ° C. or lower. By keeping the temperature at 260 ° C or lower, the heat resistance and moldability of the obtained polyurethane become good, and by keeping it at 180 ° C or higher, the moldability and quality of the obtained polyurethane become good. In addition,
Polymerization process of polyurethane or after polymerization, colorant, lubricant, crystal nucleating agent, flame retardant, ultraviolet absorber, light resistance improver,
Additives such as antioxidants, hydrolysis inhibitors and antifungal agents may be added as appropriate.

The polyurethane of the present invention has a logarithmic viscosity (ηin
h) is preferably in the range of 0.5 to 2.0 dl / g. The logarithmic viscosity of the polyurethane is 0.5 g
It can be determined by dissolving it in dimethylformamide so that it becomes / dl and measuring the solution viscosity of the solution at 30 ° C.

Since the polyurethane of the present invention has good moldability and can give a molded product having excellent mechanical properties, it is suitably used for various molding applications such as extrusion molding, injection molding and calender molding. To be done.

[0015]

The present invention will be described in detail with reference to the following examples. In the examples, hardness, logarithmic viscosity, strength and elongation, viscosity increase rate, fisheye generation amount and appearance (whitening degree) were measured by the following methods.

[Hardness] Three disks having a thickness of 2 mm obtained by injection molding were superposed and measured with a Shore A hardness meter.

[Logarithmic viscosity] 0.5g of polyurethane
The solution was dissolved in dimethylformamide so that the concentration became / dl, and the logarithmic viscosity at 30 ° C of the solution was measured.

[Strength and Elongation] Measured according to JIS K-7331. That is, a thickness of 2 m obtained by injection molding
A dumbbell-shaped test piece was prepared from a disc of m, and the tensile speed was 30
The breaking strength and breaking elongation were measured in cm / min.

[Viscosity increase rate] Using a flow tester (manufactured by Shimadzu Corporation), load 50 kgf, nozzle size 1 mmφ
Under a condition of × 10 mm and a temperature of 210 ° C., melt viscosities were measured for preheating times of 6 minutes and 60 minutes, respectively, and the viscosity increase rate was obtained from the following calculation formula.

[0020]

[Equation 1]

[Amount of Fish Eyes Generated] Polyurethane was formed into a film having a thickness of 100 μm using a single-screw extruder, and the number of fish eyes in 400 cm ² was counted.

[Appearance (whitening degree)] The transparency of a disc having a thickness of 2 mm obtained by injection molding was visually judged.
The evaluation result is a completely transparent disc (denoted by "◎"),
Semi-transparent disc with some whitening (denoted by "○")
And an opaque disk (marked with "x") in which whitening remarkably occurred were distinguished and expressed in three stages.

The compounds used in the examples are indicated by abbreviations. The compound names represented by the abbreviations are shown in Table 1 below.

[0024]

[Table 1]

[Reference Example 1] (Production of polyester diol) 2158 g of BD and 2920 g of adipic acid were charged into a reactor, and an esterification reaction was carried out at 200 ° C. under atmospheric pressure while distilling off the produced water out of the system. When the acid value of the reaction product falls below 30, tetraisopropyl titanate 90m
g was added and the reaction was continued while reducing the pressure to 200 to 100 mmHg. When the acid value reached 1.0, the degree of vacuum was gradually raised by a vacuum pump to complete the reaction. as a result,
PBA with a number average molecular weight of 3000 (hereinafter referred to as "PBA
-A ") was obtained.

Reference Example 2 (Water Deactivation of Titanium Catalyst) 1000 g of PBA-A obtained in Reference Example 1 was heated to 100 ° C., and 20 g (2% by weight) of water was added thereto and stirred for 2 After heating for a period of time to deactivate the titanium-based catalyst, water was distilled off under reduced pressure (PBA obtained by this treatment is referred to as "PBA-B").

[Reference Example 3] (Production of polyester diol) 2288 g of BD and 2920 g of adipic acid were charged in a reactor and an esterification reaction was carried out in the same manner as in Reference Example 1 to obtain a PBA having a number average molecular weight of 2000 (hereinafter referred to as "PBA"). −
4130 g).

Reference Example 4 (Water deactivation of titanium-based catalyst) After deactivating the titanium-based catalyst in the same manner as in Reference Example 2 except that the PBA-C obtained in Reference Example 3 was used, the pressure was reduced. Water was distilled off below (hereinafter, PBA obtained by this treatment is referred to as "PBA-D").

[Example 1] PBA-obtained in Reference Example 2
DBA was added to B, and PBA-B, BD, BHEB, and MDI heated and melted at 50 ° C. were added to PBA-B: B.
The molar ratio of D: BHEB: MDI is 1: 2.8: 2.8:
6.9, and the total amount of these was 200 g / min, continuously charged from a metering pump to a twin-screw type extruder rotating in the coaxial direction of L / D = 36 at 30 mmφ and kept at 250 ° C. Continuous melt polymerization was performed at temperature. The amount of DBA added was 15 ppm (5 ppm in terms of tin atom) with respect to the total amount of PBA-B, BD, BHEB, and MDI. The resulting thermoplastic polyurethane melt was continuously extruded into water in strands, then cut with a pelletizer and formed into pellets. After drying the pellets at 80 ℃ for 20 hours, 200 ℃
A circular plate having a thickness of 2 mm was formed by injection molding at 1 ° C., and allowed to stand at room temperature for 1 week. Then, hardness, logarithmic viscosity, strength / elongation, melt viscosity increase rate, fisheye generation amount and appearance (whitening degree) were measured.
The results obtained are shown in Table 3 below.

[Examples 2 to 5] The polyester diols (both containing DBA) shown in Table 2 and the chain extender were added in the same manner as in Example 1 at the molar ratios shown in Table 2 to obtain MDI. Was continuously melt-polymerized, and the resulting thermoplastic polyurethane was pelletized. The thermoplastic polyurethane pellets obtained were dried and then injection-molded to obtain the evaluation results shown in Table 3.

[Comparative Examples 1 to 3] The polyester diols (with or without DBA) and the chain extenders shown in Table 2 are shown in Table 2 in the same manner as in Example 1. Continuously melt-polymerize with MDI in a molar ratio,
The thermoplastic polyurethane produced was pelletized. The thermoplastic polyurethane pellets obtained were dried and then injection-molded to obtain the evaluation results shown in Table 3.

[0032]

[Table 2]

[0033]

[Table 3]

From Tables 2 and 3 above, in the polyurethanes of the present invention (Examples 1 to 5), there is almost no increase in melt viscosity under melting conditions and generation of fish eyes during molding, and the molded products obtained are obtained. Since there is no whitening, it can be seen that the moldability is extremely excellent. It can also be seen that the polyurethane of the present invention gives a molded article having excellent strength and elongation. On the other hand, when BD and BHEB are not used together as the chain extender (Comparative Examples 1 and 2) and when no tin catalyst is contained (Comparative Example 3), moldability and / or strength / elongation may be poor. Recognize.

[0035]

EFFECTS OF THE INVENTION The polyurethane of the present invention is excellent in moldability because the increase in melt viscosity due to retention during molding and the generation of fish eyes are suppressed, and the resulting molded product does not whiten. The molded product obtained from the polyurethane of the present invention is also excellent in strength and elongation.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michihiro Ishiguro 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (1)

[Claims] 1. A polyurethane obtained by polymerizing a polymer diol, an organic diisocyanate and a chain extender, wherein the polymer diol has a molecular weight of 1000 to 5000, and the chain extender is 1,4- Butanediol (BD) and bis (β-hydroxyethoxy) benzene (BHE
B) and the molar ratio of BD to BHEB is BD / B.
It is within the range of 35/65 to 90/10 in HEB, and the tin-based urethanization catalyst has 0.5 to 15 p as a tin atom.
Polyurethane containing pm.