JPH01168729A - Preparation of polyester elastomer - Google Patents

Abstract

PURPOSE:To obtain the title elastomer of high quality in a short reaction time while controlling by-product formation, by reacting a polyethylene terephthalate forming component and polyalkylene glycol in the presence of a specified catalyst. CONSTITUTION:A polyethylene terephthalate forming component (A) constituting a hard segment (e.g., a mixture of terephthalic acid with ethylene glycol), 5-200wt.% polyalkylene glycol (B) based on the component A constituting a soft segment and having a number-average MW of 500-5,000 (e.g., polytetramethylene glycol) are reacted in the presence of a catalyst (C) which is 0.0001-0.1wt.% soluble niobium compd. (a) heat-treated if necessary (e.g., niobic acid heat-treated at 80-400 deg.C in advance) and, if necessary, another catalyst (b).

Description

[Detailed Description of the Invention] (Industrial Application Field) Polyester elastomers, especially polyethylene terephthalate elastomers, have excellent oil and chemical resistance, and have excellent service temperature range and load resistance compared to other thermoplastic elastomers. Since it has good bending fatigue resistance, it is being widely used for automobile parts, electrical and electronic product parts, etc.

That is, the polyethylene terephthalate portion that makes up the hard segment gives the elastomer a high melting point and high crystallinity, while the polyalkylene glycol portion that makes up the soft segment has a significantly low glass transition point.
As a result, the elastomer maintains its flexibility and strength over a wide temperature range from low to high temperatures. In addition, by changing the ratio of the two, mechanical properties such as strength and elongation, and chemical properties such as oil resistance and chemical resistance can be adjusted according to the purpose and intended use.

The present invention relates to a method for producing a polyester elastomer using polyethylene terephthalate as a hard segment and polyalkylene glycol as a soft segment.

(Prior art) Conventionally, as a method for producing polyester elastomer,
Generally, there is a method in which terephthalic acid, ethylene glycol and polyalkylene glycol are esterified and then polycondensation is carried out, or a method in which polyalkylene glycol is added after the esterification reaction of the former two and then polycondensation reaction is carried out. . In such a production method, there is a problem that the polyalkylene glycol used as a raw material for the soft segment is easily thermally decomposed at high temperatures, and low-temperature polymerization takes a long time, making it difficult to obtain a polymer with a target viscosity. As a countermeasure against these problems, a method using an organic titanium catalyst (Japanese Patent Publication No. 49-31558) and a method using a combination of an organic titanium catalyst and an aromatic aldehyde acid (Japanese Patent Publication No. 55-2)
No. 9096) has been proposed.

(Problems to be Solved by the Present Invention) However, when a method using an organic titanium catalyst was examined in detail, it was found that it has the disadvantage that it is deteriorated and deactivated by moisture in the reaction system.

That is, if the amount used is sufficient to promote the reaction, turbidity will occur due to deterioration and precipitation of organotitanium, and the obtained polymer will become opaque.If the amount used is reduced, the reaction time will become longer and the polyalkylene glycol component will decompose more. etc., was not satisfactory.

Therefore, as a result of repeated research in search of an excellent catalyst, the present inventors discovered that a soluble niobium compound reduces by-products, simultaneously shortens reaction time, and provides a polymer with good physical properties. It has arrived.

(Means for Solving the Problems) The method of the present invention involves performing the reaction between the polyethylene terephthalate-forming component constituting the hard segment and the polyalkylene glycol constituting the soft segment in the presence of a soluble niobium compound as a catalyst. It is characterized by

The soluble niobium compounds used in the present invention include inorganic compounds such as niobic acid and its alkali metal salts, alkoxides,
There are organic niobium compounds such as glycolate and carboxylate, and one or more of these are used. Among these, niobic acid is one of the preferred catalysts, but it is
Those heat-treated in a temperature range of 400°C have high activity and are particularly excellent. Note that if the treatment temperature exceeds 400°C, it will be difficult to dissolve in the reaction system and the reaction promotion effect will be insufficient.

Soluble niobium compounds do not require special consideration when handled in a system open to the atmosphere, exhibit high activity without being altered or degraded by moisture produced as a by-product of the esterification reaction.

The amount of the catalyst of the present invention to be used varies depending on the reaction conditions, but is 0.000 niobium metal based on the raw material in terms of polymer.
1 to 0.1% by weight, preferably -0.001 to 0.05
Weight%.

As for the timing of adding the catalyst, it is preferable to use it from the beginning of the first esterification reaction, but a portion may be added in portions immediately before the late polycondensation reaction.

Furthermore, in the method of the present invention, manganese, magnesium, calcium, cobalt, zinc compounds, tin compounds such as dibutyltin oxide and monobutyl oxide, titanium compounds such as tetra-n-butyl titanate and potassium titanate oxalate, Antimony compounds such as antimony oxide and antimony acetate, and various known catalysts such as germanium oxide may also be present.

The polyethylene terephthalate-forming component constituting the hard segment of the present invention includes terephthalic acid and ethylene glycol, bis(4-hydroxyethyl) terephthalate or its lower condensate, terephthalic acid lower alkyl esters such as dimethyl terephthalate, and ethylene. Although it is composed of glycol and the like, it may also contain a copolymer component (50 mol% or less) in addition to these. For example, isophthalic acid, orthophthalic acid, naphthalene-2,6
- Aromatic dicarboxylic acids such as dicarboxylic acid, diphenyl-4,41-dicarboxylic acid, and 5-sulfoisophthalic acid,
1. Alicyclic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, and oxalic acid, oxycarboxylic acids such as oxybenzoic acid, and 1. other than ethylene glycol. 4-tetramethylene glycol, propylene glycol, 1°3
-tetramethylene glycol - aliphatic diols such as lumihexane diol, neopentyl glycol, cyclohexane-1,4-diol, alicyclic diols such as cyclohexane-1,2-dimethtool, cyclohexane-1,4-dimetatool, bisphenol A , bisphenol S, bis(hydroxyethoxy)bisphenol A1, and aromatic diols such as tetrabromobisphenol A. Such carboxylic acids or diols can also be used in the form of their ester-forming derivatives, such as lower alkyl esters, aryl esters, acetylated products, and the like.

The polyalkylene glycols constituting the soft segment include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymers thereof, and in particular polyalkylene glycol copolymers containing polytetramethylene glycol as the main component. preferable. The number average molecular weight of polyalkylene glycol is 5
A molecular weight of 00 to 5,000 is preferable, but a molecular weight of 1,000 to 3,000 is more preferable; if the molecular weight is too large, it tends to deteriorate and the elasticity at low temperatures decreases.

On the other hand, a polymer having a small molecular weight is not preferable because it lowers the melting point of the resulting polymer. The ratio of the hard segment component to the soft segment component varies depending on the application, but the ratio within the film is 5 to 200% by weight of the latter to the former.

The reaction conditions (temperature, pressure, time, etc.) for producing a polyester elastomer using such raw materials may be known ones, including the esterification step.

In addition, like normal polyester, heat stabilizers such as phosphorus compounds, hue modifiers such as cobalt phosphate and cobalt acetate, oxidation inhibitors such as hindered phenol, ultraviolet absorbers such as benztriazole, hydroxybenzophenone, and cyanoacrylate, Pigments and dyes such as titanium oxide and carbon black, crystal nucleating agents or fillers such as talc, wollastonite, and mica, higher fatty acid salts, crystal accelerators such as polyolefins, mold release agents, antistatic agents, lubricants, or asbestos. ,
Organic or inorganic modifiers or reinforcing agents such as synthetic fibers, glass fibers, metal fibers, carbon fibers, metal powders, and ceramic fibers may be added depending on the purpose.

(Effects of the Invention) As described above, the present invention is characterized in that a soluble niobium compound is used as a catalyst when producing a polyester elastomer by reacting a polyethylene terephthalate-forming component with a polyalkylene glycol. According to the method of the present invention, there is no deactivation of the catalyst due to moisture in the reaction system, the esterification reaction and polycondensation reaction times can be shortened, and at the same time, by-products can be significantly suppressed and high-quality polymers can be obtained.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples. Note that the intrinsic viscosity in this example refers to phenol/tel-
20°C with lachloroethane (60%/40%) mixed solvent.
The value was measured at a concentration of 1 g/dI. In addition, % and parts indicate weight % and parts by weight.

Example 1 166 parts of terephthalic acid, 75 parts of ethylene glycol,
Polytetramethylene glycol (molecular weight 1000) 10
0 parts, niobic acid preheated at 150°C for 10 hours
．． 0.025 parts were put into a reactor equipped with a stirrer equipped with a rectification column, heated under normal pressure, and the internal temperature was raised from 180°C to 2.0°C over 120 minutes.
The temperature was set at 55°C, and the water produced was distilled off. The time required for terephthalic acid to dissolve in the reaction solution was 2 hours and 50 minutes, and the amount of distillate was 33 parts. Next, the temperature was raised to 270t, and 1
The pressure was reduced to 0.5 mm and 11 g per hour, and the reaction was continued for 2 hours. The obtained polymer had an intrinsic viscosity of 0.94,
The color tone was transparent and pale yellow. 2H thick JIS K
When a dumbbell-shaped test piece was evaluated according to -6301, the breaking strength was 760 kg/cJ, and the breaking elongation was 43.
0%, and the surface hardness was 96.

In addition, as a solvent resistance test, the test piece was immersed in a solvent such as gasoline, acetone, or benzene at room temperature, but no change in shape was observed.

Comparative Example 1 Polymerization was carried out under the same conditions except that tetra-n-butyl titanate was used instead of niobic acid in Example 1. The time required for terephthalic acid to dissolve was 3 hours and 20 minutes. The amount of distillate was 35 parts, the intrinsic viscosity of the polymer was 0.682, and the color was opaque and yellowish brown.

Examples 2 to 10 Polymerization reactions were carried out under the same conditions as in Example 1, except that the heat treatment temperature and amount added were different.
Table 1 with blank spaces Example 11 Polymerization was carried out under the same conditions as in Example 1 except that sodium niobate was used instead of the niobic acid catalyst. The polymer had an intrinsic viscosity of 1.05 and was transparent and pale. A yellow substance was obtained.

Example 12 194 parts of dimethyl terephthalate, 150 parts of ethylene glycol, 100 parts of polytetramethylene glycol (molecular weight 2000), 0.5 part of an antioxidant (Ionosox, Shell Petroleum 330), and 0.02 part of niobium butoxide as a catalyst. The mixture was placed in an autoclave, heated under stirring, and the internal temperature was raised from 180°C to 255°C in 100 minutes, during which time methanol resulting from the transesterification reaction was distilled off. Next, the internal temperature was raised to 250° C., the pressure was gradually reduced to 0.5 dragon Hg over 30 minutes, and a polycondensation reaction was carried out for 2 hours. The obtained polymer had an intrinsic viscosity of 0.88 and a good color tone, being pale yellow and transparent.

Claims (5)

[Claims] (1) A method for producing a polyester elastomer, characterized in that the reaction between the polyethylene terephthalate-forming component constituting the hard segment and the polyalkylene glycol constituting the soft segment is carried out in the presence of a soluble niobium compound as a catalyst. (2) The method according to claim 1, wherein the polyalkylene glycol is polytetramethylene glycol. (3) The method according to claim 1, wherein the soluble niobium compound is present in the produced polymer in an amount of 0.0001 to 0.1% by weight as niobium metal. (4) The method according to claim 1, wherein the soluble niobium compound is niobic acid. (5) The method according to claim 4, wherein the niobic acid is previously heat-treated in a temperature range of 80 to 400°C.