JPH10218962A - Method for producing thermoplastic polyurethane resin with less fish eyes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for obtaining a thermoplastic polyurethane resin of any composition, which has less fish eyes, is excellent in moldability and durability, and has various compositions. SOLUTION: In a method for producing a thermoplastic polyurethane resin using (a) an organic diisocyanate, (b) a polymer polyol, (c) a chain extender, and (d) a bismuth carboxylate, the following production conditions (1) and This is a method for producing a thermoplastic polyurethane resin having less fish eyes, which satisfies (2). Production conditions (1) Total isocyanate groups / Total hydroxyl groups = 0.82 / 1.
00 to 1.18 / 1.00

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a thermoplastic polyurethane resin. More specifically,
The present invention relates to a method for producing a thermoplastic polyurethane resin having a low fish eye, which can be carried out with any composition and has good moldability and durability.

[0002]

2. Description of the Related Art Thermoplastic polyurethane resin (hereinafter TPU)
Is a typical example of a thermoplastic elastomer (hereinafter abbreviated as TPE) because of its excellent properties such as mechanical strength, rubber elasticity, abrasion resistance, chemical resistance, and cold resistance. It is in the position. Furthermore, TPU is used in various applications because it is a material excellent in processability that can easily obtain a molded product by an industrial machine that processes ordinary TPE.

[0003] TPU is generally produced using a high-molecular polyol, a chain extender, and an organic isocyanate as raw material components. The actual production of TPU is carried out by various methods, such as a method in which the raw materials are mixed and then reacted in a twin-screw extruder or a belt, or a batch reaction in a kneader such as a kneader. In general, a method for causing the above is performed.

[0004] As a problem during the production of the TPU, a partial gel-like substance often referred to as fisheye may occur. One of the causes of generation of fish eyes is that the chain extender and the organic isocyanate partially concentrate in the reaction system, and a component having an abnormally high hard segment content is formed. The component having an unusually high hard segment content often appears as a fish eye on the surface of the TPU or becomes a gel-like insoluble component when dissolved in a solvent. Another cause of fisheye is the formation of an allophanate group due to an abnormal reaction. The TPU in which fish eyes are generated tends to cause poor appearance of the molded product, deterioration of physical properties, and the like, and thus often cannot be used as an industrial product.

[0005] In the past, there have been reported several examples of studies for reducing fish eyes. For example, 1) The method described in JP-A-5-214062, in which the raw materials are vigorously stirred and rapidly mixed. 2) A method using a prepolymer described in JP-A-5-271370. 3) A method using a compatibilizer between a polymer polyol and a chain extender described in JP-A-6-166538. 4) A method using a specific chain extender and a specific amount of a tin catalyst described in JP-A-7-138339. 5) A method described in JP-A-7-206963, in which a specific organic diisocyanate and a specific chain extender are used in specific amounts. 6) A method using a heat-resistant processing stabilizer described in JP-A-8-81624. Etc.

[0006] Problems with the above described method include:
The method (1) requires a powerful stirrer, and the method (2) increases the number of TPU production steps. In the methods 3) and 6), it is necessary to add a special third component. Further, the methods 4) and 5) have a point that the composition of the obtained TPU is limited.

In the production of urethane elastomers,
The use of bismuth salts of carboxylic acids is already known. For example, the technique described in JP-A-61-235420 obtains a polyurethane elastomer by using a bismuth salt of a carboxylic acid in an amount of 0.01 to 1.50% by weight based on all reaction components. However, JP-A-61-23
When a TPU was manufactured by the method described in US Pat.
It was found that fish eyes occurred relatively frequently.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a production method for obtaining a TPU of any composition, which has less fish eyes, and is excellent in moldability and durability.

For this purpose, the present inventors have conducted intensive studies and found that the production method of adding a specific amount of a specific bismuth salt of a specific carboxylic acid has a low fish eye, a low formability and a high durability. It was found that a TPU with good composition and all compositions was obtained, and the present invention was completed.

[0010]

In order to achieve the above object, the present invention provides (a) an organic diisocyanate, (b)
A method for producing a thermoplastic polyurethane resin using a polymer polyol, (c) a chain extender, and (d) a bismuth carboxylate, wherein the following production conditions (1) and (2) are satisfied. A method for producing a small amount of thermoplastic polyurethane resin. Production conditions (1) Total isocyanate groups / total hydroxyl groups = 0.82 / 1.
00 to 1.18 / 1.00

[0011]

DETAILED DESCRIPTION OF THE INVENTION As the organic diisocyanate (a) used in the present invention, 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 4,4'-MDI),
2,4'-MDI, 2,2'-MDI, 2,4-tolylene diisocyanate (hereinafter abbreviated as 2,4-TDI),
2,6-TDI, paraphenylene diisocyanate,
Aromatic isocyanates such as 1,5-naphthalenediisocyanate, ortho-oxylylene diisocyanate, meta-toxylylene diisocyanate, para-toxylylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as HDI), isophorone diisocyanate, dicyclohexylmethane diisocyanate, bis (isocyanatemethyl) Alicyclic or aliphatic isocyanates such as cyclohexane; Also, a mixture of these can be used. If necessary, urethane-modified, carbodiimide-modified, uretonimine-modified, isocyanurate-modified, uretdione-modified, and buret-modified isocyanates of the above-mentioned isocyanates can be used.

The high molecular polyol (b) used in the present invention includes polyester, polylactone, polyether, polyether-ester and polycarbonate polyols. Also, a mixture of these can be used.

Examples of polyester-based polyols include ethylene glycol (hereinafter abbreviated as EG), 1,2-
Propanediol (hereinafter abbreviated as 1,2-PD), 1,3
-Propanediol (hereinafter abbreviated as 1,3-PD), 1,
2-butanediol (hereinafter abbreviated as 1,2-BD), 1,
3-butanediol (hereinafter abbreviated as 1,3-BD), 1,
4-butanediol (hereinafter abbreviated as 1,4-BD), 1,
4-butenediol, 1,3-butenediol, 1,6
-Hexanediol (hereinafter abbreviated as 1,6-HD), 1,
9-nonanediol (hereinafter abbreviated as 1,9-ND), 3-
Methyl-1,5-pentanediol (hereinafter abbreviated as MPD), neopentyl glycol (hereinafter abbreviated as NPG),
Polyhydric alcohols such as 1,5-pentanediol, glycerin, and trimethylolpropane (hereinafter abbreviated as TMP); low-molecular-weight polyols having a molecular weight of less than 300 such as polyols derived from dimer acid; and adipic acid and sebacic acid , Azelaic acid, terephthalic acid, isophthalic acid,
Examples thereof include polyester diols obtained from aliphatic or aromatic dicarboxylic acids such as maleic acid.

The lactone-based polyol includes, for example, polycaprolactone diol, polypropiolactone diol, polyvalerolactone diol and the like.

Examples of the ether polyol include polyalkylene ether diols such as polyethylene glycol, polypropylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.

Examples of the polyether-ester polyol include compounds prepared from the above-mentioned polyether polyol and the above-mentioned dicarboxylic acids, acid anhydrides and the like.

Examples of the polycarbonate polyol include EG, 1,2-PD, 1,3-PD, 1,
4-BD, 1,3-BD, 1,4-butenediol, 1,
3-butenediol, 1,6-HD, MPD, NPG,
It is obtained by a dealcoholation reaction between a polyhydric alcohol such as 1,5-pentanediol, 1,9-ND, glycerin, and TMP, and a dialkyl carbonate such as diethyl carbonate or dipropyl carbonate, or a dephenol reaction with diphenyl carbonate. And polycarbonate diol.

The average number of functional groups of these high molecular polyols is 2 to 3, preferably 2. When the average number of functional groups is less than 2, the molecular weight of the obtained TPU does not become sufficiently large, and as a result, it is difficult to obtain those having satisfactory mechanical strength and durability. On the other hand, if it exceeds 3, gelation occurs in the entire reaction system during TPU production, and it is difficult to obtain the target TPU itself.

The high molecular polyol has a number average molecular weight of 300 to 5,000, preferably 500 to 3,000.
It is. When the number average molecular weight is less than 300, the resulting TPU has an excessively high urethane group concentration, and the melting temperature of the obtained TPU tends to be unnecessarily high. When the number average molecular weight exceeds 5,000, the TPU obtained tends to have insufficient mechanical strength and durability.

Examples of the chain extender (c) used in the present invention include EG, 1,2-PD, 1,3-PD, 1,
4-BD, 1,3-BD, 1,4-butenediol, 1,
3-butenediol, 1,6-HD, MPD, NPG,
1,5-pentanediol, 1,4-bis (β-hydroxyethoxy) benzene, methyloctanediol,
Polyhydric alcohols such as 9-ND, glycerin, and TMP are exemplified. Also, a mixture of these can be used.

Examples of the bismuth salt of the carboxylic acid (d) used in the present invention include bismuth octylate, bismuth neodecanoate, bismuth stearate, bismuth oleate and the like. It also contains a bismuth salt derived from a mixture of two or more as the carboxylic acid component,
For example, a bismuth salt derived from a mixture of neodecanoic acid and octylic acid and bismuth and the like can be mentioned. Of these, bismuth octylate is most preferred.

In the present invention, the relationship between the total number of hydroxyl groups and the total number of isocyanate groups is as follows: total isocyanate groups / total hydroxyl groups =
0.82 / 1.00 to 1.18 / 1.00, preferably 0.85 / 1.00 to 1.15 / 1.00. When the ratio of total isocyanate groups / total hydroxyl groups is less than 0.82, the molecular weight of the obtained TPU is too small, so that those having unsatisfactory mechanical strength and durability are likely to be obtained. On the other hand, if the ratio of total isocyanate groups / total hydroxyl groups is more than 1.18, an unnecessarily large number of isocyanate groups will be present at the terminals of the obtained TPU.
However, it is easy to obtain what is not very good.

The addition amount of (d) is as described in (a) to (c) above.
0.0002 to 0.0080% by weight based on the total amount of
Preferably, it is 0.0005 to 0.0075% by weight. If it exceeds 0.0080% by weight, partial gelation occurs,
That is, fish eyes are likely to occur.

As the reaction apparatus used in the present invention, a conventional apparatus can be used. Specifically, an extruder,
And kneaders. Use of an extruder enables continuous production, which is advantageous for production of general-purpose products. If a kneader is used, batch production is performed, which is advantageous for production of special products and the like.

In the present invention, various additives other than the above-mentioned components can be used. For example, catalysts, fillers, antioxidants, UV absorbers, dyes, pigments,
Lubricants, plasticizers, hydrolysis inhibitors, tackifiers, blocking inhibitors, fungicides, flame retardants, antistatic agents and the like.

[0026]

According to the present invention, it has become possible to provide a TPU having a small amount of gel-like substance called fish eye. Further, the TPU obtained according to the present invention exhibited better moldability and heat resistance than those obtained by the conventional production method. Further, the method for producing a TPU of the present invention can be applied to TPUs of any composition.

[0027]

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 examples. In Examples and Comparative Examples, “parts” were used.
Means "parts by weight", and "%" means "% by weight".

The raw materials used in the present invention are as shown below. (Organic diisocyanate) 4,4'-MDI: 4,4'-diphenylmethane diisocyanate HDI: hexamethylene diisocyanate (polymer polyol) Polybutylene adipate diol (PBA-100)
0): number average molecular weight 1000, average number of functional groups 2 polytetramethylene ether diol (PTG-100
0): Number average molecular weight 1000, average functional group number 2 Dimer acid based polyol (PP-200): Number average molecular weight 1000, average functional group number 2 poly (3-methylpentanediol) adipate (MP
A-1000): number average molecular weight 1000, average number of functional groups 2 (chain extender) 1,4-BD: 1,4-butanediol 1,6-HD: 1,6-hexanediol (bismuth carboxylate) octyl Bismuth acid (tin compound) dibutyltin diacetate

Examples 1 to 7 In accordance with the mixing ratios shown in Table 1, each component of a polymer polyol, a chain extender and an organic diisocyanate to which a bismuth carboxylate and / or a tin compound was added was discharged from a metering pump. And a twin screw extruder (30φ, L / D: 32.
The raw material is continuously supplied to the hopper section of 5), the temperature in the cylinder reaction system is 220 ° C., the temperature of the adapter and the die are 210
TPU pellets were continuously produced at ℃.

Example 8 In Example 2, the polymer polyol to which bismuth carboxylate and tin compound were added was allowed to stand at 80 ° C. for 10 days, and a twin-screw extruder was used in the same manner as in Example 2. Used to produce TPU pellets continuously.

Example 9 In Example 5, the polymer polyol to which bismuth carboxylate was added was allowed to stand at 80 ° C. for 10 days, and then, using a twin-screw extruder in the same manner as in Example 5, TPU pellets were produced continuously. Examples 1 to 9 are shown in Table 1.

[0032]

[Table 1]

Comparative Examples 1 to 7 In accordance with the mixing ratios shown in Table 2, each component of a polymer polyol, a chain extender and an organic diisocyanate to which a bismuth carboxylate and / or a tin compound was added was discharged from a metering pump. And a twin screw extruder (30φ, L / D: 32.
The raw material is continuously supplied to the hopper section of 5), the temperature in the cylinder reaction system is 220 ° C., the temperature of the adapter and the die are 210
TPU pellets were continuously produced at ℃.

COMPARATIVE EXAMPLE 8 In Comparative Example 2, after the polymer polyol to which the tin-based compound was added was left at 80 ° C. for 10 days, it was continuously used in the same manner as in Comparative Example 2 using a twin-screw extruder. Produced TPU pellets.

Comparative Example 9 In Comparative Example 4, the high molecular polyol to which the tin compound was added was allowed to stand at 80 ° C. for 10 days, and then continuously produced using a twin-screw extruder in the same manner as in Comparative Example 4. Produced TPU pellets. Table 2 shows Comparative Examples 1 to 9.

[0036]

[Table 2]

Extrusion Formability Test Using the TPUs obtained in Examples and Comparative Examples, a belt die having a width of 50 mm and a thickness of 1 mm was attached to the tip of a single screw extruder (50φ, L / D: 25). An extruded belt was prepared at a cylinder temperature of 190 ° C., a belt die temperature of 200 ° C., and a screw rotation speed of 20 rpm. The number of fish eyes per unit area generated on the extrusion belt was counted and evaluated. Extrusion belt area 3
Number of fish eyes per 0 cm ² is 5 or less: ◎ Range of 5 to 20: ○ Range of 20 to 50: △ 50 or more: ×

Injection Moldability Test Using the TPUs obtained in the Examples and Comparative Examples, an injection molding machine (mold clamping force 130 ton, 40φ, L /
D: 20), cylinder temperature in the range of 190 to 198 ° C., nozzle temperature in the range of 194 to 203 ° C., injection pressure 40
~ 47 kg / cm ² , with a thickness of 2 m
m, a molded product of 120 mm × 120 mm was molded. Visually observe the burr, sink mark condition of this finished product,
evaluated. No burrs or sink marks: ◎ Molded products with only burrs or sink marks: 成形 Molded products with both burrs and sink marks: ×

Mechanical Strength Test A dumbbell piece was prepared from a molded product formed by injection molding, and the tensile strength was measured according to JIS K-6301.

Heat resistance test A dumbbell piece was prepared from a molded article molded by injection molding, left in a hot air system at 120 ° C. for 500 hours, and then subjected to JIS.
The tensile strength and the retention were measured according to K-6301.
The formula for calculating the retention is as follows.

Dimethylformamide solubility test TPs obtained in Examples 1 to 11 and Comparative Examples 1 to 9
To 10 parts of U pellets, add dimethylformamide (D
After adding 90 parts of MF) and stirring and mixing at room temperature, the solution was transferred to a glass bottle, and the undissolved gel was visually observed. When the DMF solution is completely transparent: ◎ When the DMF solution is cloudy or when an undissolved gel is present: × Extrusion moldability test, injection moldability test, mechanical strength test,
Table 3 shows the evaluation results of the heat resistance test and the DMF solubility test.

[0042]

[Table 3]

Claims (1)

[Claims] In a method for producing a thermoplastic polyurethane resin using (a) an organic diisocyanate, (b) a polymer polyol, (c) a chain extender, and (d) a bismuth carboxylate, the following production conditions (1) And (2) a method for producing a thermoplastic polyurethane resin having a small amount of fish eyes. Production conditions (1) Total isocyanate groups / total hydroxyl groups = 0.82 / 1.
00 to 1.18 / 1.00