JP2000355650A - Production of polyester elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-molecular-weight elastomer excellent in blow moldability and mechanical strengths by melt-kneading a composition containing a specified polyester block copolymer, an at least trifunctional epoxy compound, and a lithium carboxylate. SOLUTION: This elastomer is obtained by melt-kneading (A) a polyester block copolymer containing blocks of a polyalkylene ether glycol, 0.1-4 pts.wt., per 100 pts.wt. component A, (B) at least trifunctional epoxy compound, and 0.05-3 pts.wt., per 100 pts.wt. component A, (C) lithium carboxylate. Component A is desirably one obtained from a dicarboxylic acid based on terephthalic acid or an esterifiable derivative thereof, a low-molecular-weight glycol or an esterifiable derivative thereof, and a polyalkylene ether glycol. Component B is desirably a tri- to pentadeca-functional epoxy compound. Component C is desirably a lithium 2-50C aliphatic carboxylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyester elastomer, and more particularly, to a method for producing a polyester elastomer based on a polyester block copolymer having a block of polyalkylene ether glycol. The high-molecular-weight, high-viscosity polyester-based elastomer thus produced is excellent in hollow moldability and mechanical strength, and is useful for producing various molded products.

[0002]

2. Description of the Related Art Thermoplastic elastomers have attracted attention as rubbery soft materials which do not require a vulcanizing step and have the same moldability as thermoplastic resins. Styrene, olefin, polyester, polyamide, polyurethane Various types such as systems are used in the fields of automobile parts, home electric parts and the like. Furthermore, in recent years, from the viewpoint of process rationalization, recycling, and the like, expectations as substitute materials for conventional vulcanized rubber have been increasing. Above all, polyester-based elastomers are widely used in various applications including electric products and automobiles, utilizing their good moldability, heat resistance, oil resistance and low-temperature properties.

[0003] This polyester elastomer is generally produced by a melt polymerization method. However, in order to prevent the decomposition of polyalkylene ether glycol, the polymerization is often carried out at a relatively low temperature. In view of this, the molecular weight, that is, the melt viscosity was low, and although it could be used for injection molding, it was insufficient for hollow molding. As a method for increasing the melt viscosity to the extent that hollow molding is possible, a solid-state polymerization method, a method of blending an ionomer, a method of adding a polyepoxy compound, and the like are known (JP-A-51-143055, JP-A-48-100495).

[0004] Among them, the solid-phase polymerization method requires a long time reaction to obtain a high viscosity, which is not very economical, and the method of blending the ionomer has poor compatibility between the polyester elastomer and the ionomer. Since only about 10 to 20% of ionomer can be used,
It is difficult to obtain one with a sufficiently high viscosity. Regarding the method of adding a polyepoxy compound, it is described in JP-A-48-100495 that the viscosity of the polyester-based elastomer is increased by reacting the polyepoxy compound with the terminal carboxyl group of the polyester-based block copolymer. However, in this reaction, in order to obtain an elastomer having a practical viscosity, it is necessary to use a catalyst such as an amine, and on the other hand, the heat aging property, which is considered to be caused by this catalyst, occurs. Therefore, there was a problem in practicality.

[0005] As a catalyst for the reaction between the polyester-based block copolymer and the polyepoxy compound, which is considered to have relatively no adverse effect on the heat aging property, a metal salt of an organic carboxylic acid (for example, calcium stearate, Although zinc naphthenate and sodium acetate have also been proposed, zinc naphthenate and sodium acetate have low catalytic activity, and the viscosity of the polyester elastomer may decrease during melt mixing. Although calcium stearate has a certain degree of catalytic activity, the range of the added amount in which the effect can be obtained is narrow, and if it is outside this range, the viscosity may be reduced and it is difficult to use.

A method using a diepoxy compound and a metal salt of an organic carboxylic acid (for example, potassium laurate, sodium stearate, sodium oleate, etc.) is disclosed in JP-A-57-36124. However, potassium laurate, sodium stearate,
Sodium oleate requires a long time for the reaction, is not economical, and a method for producing a high molecular weight polyester-based elastomer which is industrially excellent has not yet been established.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a high molecular weight polyester elastomer excellent in hollow moldability and mechanical strength. It is in.

[0008]

Means for Solving the Problems The present inventors have made various studies in order to solve the above-mentioned problems, and as a result, have found that a polyester-based block copolymer and a polyepoxy compound have a specific carboxylic acid metal salt. And found that the above-mentioned problems can be solved by melt-kneading, thereby completing the present invention. That is, the gist of the present invention is to provide a polyester-based block copolymer containing a block of polyalkylene ether glycol, 0.1 to 4 parts by weight of a tri- or higher functional epoxy compound per 100 parts by weight of the copolymer, and 0 Melt-kneading a composition containing 0.05 to 3 parts by weight of a lithium carboxylate.

Another gist of the present invention is to provide a method for producing the above-mentioned polyester elastomer wherein the number average molecular weight of the block portion of the polyalkylene ether glycol of the polyester block copolymer is from 400 to 6,000. The method for producing a polyester elastomer as described above, wherein the polymer is obtained from a dicarboxylic acid mainly composed of terephthalic acid or an ester-forming derivative thereof, a low molecular weight glycol or an ester-forming derivative thereof, and a polyalkylene ether glycol. Exist.

Another gist of the present invention is that an epoxy compound has 3
A method for producing the above-mentioned polyester-based elastomer which is an epoxy compound having -15 to 15 functions, a method for producing the above-mentioned polyester-based elastomer wherein the polyalkylene ether glycol is polytetramethylene ether glycol, and the method wherein the lithium carboxylate has 2 to 50 carbon atoms And the above-mentioned method for producing a polyester elastomer which is a lithium salt of an aliphatic carboxylic acid. Another gist of the present invention is a method for producing the above-mentioned polyester-based elastomer, wherein the melt-kneading is performed using a single-screw or twin-screw extruder at a temperature of 160 to 300 ° C and an average residence time of 6 seconds to 60 minutes. , Also exists.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a polyester block copolymer which can be used in the method for producing a polyester elastomer of the present invention, a hard segment is an aromatic polyester block and a soft segment is an aliphatic polyether block. The constituent poly (ether ester) block copolymers are preferred, especially block copolymers obtained from dicarboxylic acids such as terephthalic acid or their ester-forming derivatives, low molecular weight glycols or their ester-forming derivatives and polyalkylene ether glycols. Poly (ether ester) polymers are preferred. This block copolymer usually has a carboxyl group at its terminal.

Examples of the polyalkylene ether glycol include polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, a block or random copolymer of ethylene oxide and propylene oxide, and ethylene oxide. And a random copolymer of styrene and tetrahydrofuran, among which polytetramethylene ether glycol is preferable. The weight average molecular weight of the polyalkylene ether glycol is 400 to
It is preferably 6,000, particularly preferably 600 to 3,000, and the content of the polyalkylene ether glycol block in the copolymer is preferably 5 to 95% by weight. A more preferred content of polyalkylene ether glycol is 10 to 85% by weight, particularly preferably 20 to 80% by weight.

When the content is less than 5% by weight, the viscosity can be increased by a conventional method, but the flexibility of the obtained polyester elastomer tends to decrease. If the content is too high, the blocking property is impaired, so that it is difficult to reduce the material strength and to exhibit rubber-like properties. In the present invention, as the dicarboxylic acid or its ester-forming derivative, phthalic acid, terephthalic acid, isophthalic acid, 1,4- or 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4 ′ -Diphenyl ether dicarboxylic acid, 4,
Examples thereof include aromatic dicarboxylic acids such as 4′-diphenylsulfone dicarboxylic acid and the like and alkyl esters thereof. Examples of the low molecular weight glycol or the ester-forming derivative thereof include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol and hexamethylene glycol. Aliphatic diols such as methylene glycol, 1,4-
Alicyclic diols such as cyclohexanediol and 1,4-cyclohexanedimethanol; aromatic diols such as 4,4'-dihydroxybiphenyl and 2,2-bis (4'-β-hydroxyethoxyphenyl) propane; Esters with carboxylic acids can be exemplified. Each of these components may contain one kind or two or more kinds.

The polyester block copolymer used in the present invention has a flexural modulus specified by JIS K 7203 of 1000 MPa or less, preferably 600 MPa.
a, particularly preferably 300 MPa or less, and a melting peak temperature by a differential scanning calorimeter of 100 to 230 ° C, more preferably 130 to 220 ° C. The density of this copolymer is 1.00 to 1.3.
0 g / cm ³ , more preferably 1.01 to 1.25 g /
It is preferably cm ³ . As such a block copolymer, for example, "Primalloy" (trade name, manufactured by Mitsubishi Chemical Corporation) "Perprene S", "Perprene P" (trade name, manufactured by Toyobo Co., Ltd.), "Hytrel" (trade name, manufactured by Toray DuPont) Name), "Lomod" (trade name, manufactured by Nippon GE Plastics), "Flekmer" (trade name, manufactured by Nippon Synthetic Chemical Industry), "Nouvellen" (trade name, manufactured by Teijin Limited), "Greak E" (Dainippon Ink) It can be appropriately selected from commercially available products such as Chemical Industry Co., Ltd.) and used.

The epoxy compound used in the present invention has at least three epoxy groups in the same molecule (3
The structure is not particularly limited as long as it is a functional one. More preferred epoxy compounds are 3 to 15 functional epoxy compounds. Specifically, tetrahydroxyphenylmethane tetraglycidyl ether, novolak glycidyl ether, glycerin triglycidyl ether, tetraglycidyl diaminodiphenylmethane, triglycidyl isocyanurate, epoxidized soybean oil, orthocresol novolac glycidyl ether, and formula (1),
Polyfunctional alicyclic epoxy compounds as shown in (2) can be exemplified.

[0016]

Embedded image

[0017]

Embedded image

The amount of the epoxy compound is 0.1 to 4 parts by weight per 100 parts by weight of the polyester block copolymer. If this amount is less than 0.1 parts by weight,
The viscosity of the polyester elastomer obtained by melt-kneading the composition does not become sufficiently high. On the other hand, if this epoxy compound is added in an amount exceeding 4 parts by weight, excessive bonding between polymer chains occurs and moldability deteriorates. It is not preferable because it tends to occur.

Examples of the carboxylic acid forming the lithium carboxylate which is an essential component of the present invention include aliphatic monocarboxylic acids, aromatic monocarboxylic acids, aliphatic dicarboxylic acids, and aromatic dicarboxylic acids. The number of atoms is 2 to 50. As the carboxylic acid component, a monocarboxylic acid or a dicarboxylic acid is preferable, and a monocarboxylic acid is particularly preferable. As aliphatic monocarboxylic acids, acetic acid,
There are propionic acid, butyric acid, pentanoic acid, hexanoic acid, succinic acid, nonanoic acid, stearic acid, and the like. , Dimer acid and the like.

As the metal forming the metal carboxylate, lithium (Li) is used. In the case of metals other than lithium, the reaction between the epoxy group and the carboxyl group is slowed down, and it takes a long time for melt-kneading, so that the polymer may be deteriorated during kneading. Particularly preferred among lithium carboxylate salts is lithium stearate. The amount of the lithium carboxylate used in the method of the present invention is 0.05 to 3 parts by weight per 100 parts by weight of the polyester-based block copolymer. If the added amount is less than 0.05 part by weight, the reaction promoting effect tends to be insufficient. On the other hand, if the added amount is more than 3 parts by weight, the effect corresponding to the added amount cannot be obtained, and bleeding may occur in some cases. It is not so preferable because it becomes easy.

The polyester-based elastomer produced by the method of the present invention may further include, if necessary, other optional components such as calcium carbonate, in addition to the above components, as long as the effects of the present invention are not impaired. Filler such as titanium oxide, talc, mica, whisker, glass fiber, carbon fiber, and antioxidant, heat stabilizer, light stabilizer, ultraviolet absorber, neutralizer, lubricant, lubricant, anti-fog agent, blocking An inhibitor, an antistatic agent, an antibacterial agent, a fluorescent whitening agent, a dispersant, a flame retardant, a colorant, a foaming agent, a crosslinking agent, a crosslinking assistant, and the like may be added.

The production of the polyester elastomer of the method of the present invention comprises the steps of:
This is carried out by melt-kneading raw materials of an essential component of a functional or higher functional epoxy compound and lithium carboxylate, and other additives. This melt kneading, for example, after uniformly mixing each component such as powdery or granular or liquid by a mixer such as a Henschel mixer, a ribbon blender, a V-type blender, a single-screw or multi-screw extruder, a kneader,
This is performed using a Banbury mixer, a roll, or the like. Epoxy compounds and other liquid components are pumped
It may be added before or after the polyester-based elastomer is melted. As the melt kneader to be used, an extruder is preferable, and among them, a single screw or twin screw extruder, particularly a twin screw extruder is preferable.

As the conditions for the melt-kneading, the resin temperature in the kneader is preferably from 160 ° C. to 300 ° C., more preferably 180 ° C. to 260 ° C. If the resin temperature in the kneader during melt kneading is lower than 160 ° C., the reaction does not proceed sufficiently, and it is difficult to obtain a high-viscosity polyester-based elastomer. On the other hand, when this temperature exceeds 260 ° C., thermal degradation of the polymer starts, and the mechanical strength and the hue of the resulting polyester elastomer tend to deteriorate. The average residence time in the kneader during the melt-kneading is preferably from 6 seconds to 60 minutes. When the average residence time is less than 6 seconds, the reaction does not proceed sufficiently and it is difficult to obtain a high molecular weight polymer. On the other hand, when the average residence time exceeds 60 minutes, the above-mentioned thermal degradation of the polymer tends to occur.

The maximum shear rate in the melt mixer is preferably 50 sec ^{-1 to} 20,000 sec ^-1 or less. When the shear rate is less than 50 sec ⁻¹ , the polyester block copolymer, the epoxy compound, and the lithium carboxylate are not sufficiently dispersed, so that a local crosslinked product is generated, and a uniform high-viscosity polyester elastomer is obtained. It is difficult to get. On the other hand, when the shear rate is higher than 20,000 sec ⁻¹ , a decrease in molecular weight or coloring may occur due to thermal decomposition of the polymer due to local shear heat generation. Control of various conditions such as resin temperature in the kneader during melt kneading, residence time, shear rate, etc. within the above range, for example, in the case of an extruder, its cylinder temperature, screw shape, screw rotation speed or screw and cylinder. It is possible by adjusting the gap (tip clearance) and the like.

By using the method of the present invention, a polyester elastomer having a high molecular weight (high viscosity) can be obtained.
Such high-molecular-weight polyester-based elastomers are produced by various molding methods commonly used for molding thermoplastic resins and thermoplastic elastomers, such as injection molding, extrusion molding, hollow molding, compression molding, rotational molding, and thermoforming. Although it can be molded into a desired molded product by the method, it can be suitably used for the production of a hollow molded product by utilizing its high molecular weight.

[0026]

EXAMPLES Hereinafter, the method of the present invention will be described more specifically and in detail using examples, but the present invention is not limited to the following examples unless it exceeds the gist. <Components> Polyester block copolymer (shown with “A” attached)
Be) A-1; polybutylene terephthalate block as a hard section reinforcement, polytetramethylene ether glycol (number average molecular weight 2000) poly (ether ester block and a soft segment) block copolymer (a polytetramethylene ether glycol block Content ratio 72% by weight, flexural modulus 20 MPa, density 1.0
7 g / cm ³ , melting end temperature by differential scanning calorimetry 16
7 ° C.) A-2: Polyester thermoplastic elastomer comprising a poly (ether ester) block copolymer having a polybutylene terephthalate block as a hard section and a polytetramethylene ether glycol (number average molecular weight 1000) block as a soft segment (Polytetramethylene ether glycol block content 52
Weight%, flexural modulus 80 MPa, density 1.15 g / cm
^3. Melting end temperature by differential scanning calorimetry: 182 ° C) A-3: Poly (ether ester) block having a polybutylene terephthalate block as a hard section and a polytetramethylene ether glycol (number average molecular weight of 1,000) block as a soft segment Polyester thermoplastic elastomer made of copolymer (polytetramethylene ether glycol block content 35
Weight%, flexural modulus 165 MPa, density 1.19 g / c
m ³ , melting end temperature by differential scanning calorimetry 205 ° C)

Epoxy compound (indicated with "B") B-1; Epoxidized 3-cyclohexene 1,2-dicarboxylic acid bis (3-cyclohexenylmethyl) -modified ε-caprolactone (manufactured by Daicel Chemical Industries, Ltd.) "Eporide GT302", epoxy equivalent 272, formula (1)) B-2: Epoxidized butenetetracarboxylic acid tetrakis (3-cyclohexenylmethyl) -modified [epsilon] -caprolactone (manufactured by Daicel Chemical Industries, Ltd .; "Eporide GT4").
03 ", epoxy equivalent 278, formula (2)) B-3; 3,4-epoxycyclohexylmethyl (3,
4-epoxycyclohexane) carboxylate (“Epicoat 171”, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 140)

Metal salts of carboxylic acids (shown with the letter “C”)
C-1 ) Lithium stearate (manufactured by Wako Pure Chemical Industries, Ltd.) C-2: Sodium stearate (manufactured by Wako Pure Chemical Industries, Ltd.) Other additives (indicated with “D”) D-1; Phenolic antioxidant ("Irganox 1010" manufactured by Ciba-Geigy) and thioether-based antioxidant ("Seanox 412S" manufactured by Shiraishi Calcium)
A mixture with an equal weight ratio of

<Examples 1 to 15, Comparative Examples 1 to 18, Reference Examples 1 to 3> Table 1 (Example) or Table 2 (Comparative Example, Reference Example)
After mixing the polyester-based block copolymer, the metal stearate and the additive in advance with a Henschel mixer at the mixing ratio shown in Table 1, a co-rotating twin-screw kneading extruder (screw diameter D; 30 mm, screw length L; 1575m
m, L / D: 52.5, "TEX30" manufactured by Japan Steel Works, Ltd.
α ”). A predetermined amount of the epoxy compound shown in the table is press-fitted into the first kneading section of the three-stage kneading section, and is melted under the conditions of the processing amount, screw rotation speed, and kneader set temperature (= resin temperature) shown in the table. The mixture was kneaded and pelletized to produce a polyester elastomer composition.

The obtained pellets were measured for melt flow rate and reduced specific viscosity under the following conditions. After drying at 100 ° C. for 4 hours, the injection pressure was 500 kg / cm ² and the injection temperature was 240 using an in-line screw type injection molding machine (“IS90B” manufactured by Toshiba Machine Co., Ltd.).
Injection molding was performed under the conditions of 40 ° C and a mold temperature of 40 ° C.
Create a sheet of 0mm x width 120mm x thickness 3mm,
The hardness, tensile strength, flexural modulus, and impact strength of each of the obtained injection molded sheets were measured under the following conditions.
The results are shown in Table 1 (Example) or Table 2 (Comparative Example, Reference Example). Similarly, using the dried pellets, a hollow molding machine IPB-10BML (a ring piston accumulator specification) manufactured by Ishikawajima-Harima Heavy Industries, Ltd. was used, and the workability was evaluated. The results are shown in Table 1 (Example) or Table 2 (Comparative Example, Reference Example). In Reference Examples 1 to 3, the polyester-based block copolymers used in Examples and Comparative Examples were independently evaluated without performing melt-kneading.

<Evaluation Method> Melt Flow Rate (MFR) The obtained pellet was subjected to MFR at 230 ° C. under a load of 2.16 kg according to JIS-K-7210.
Was measured. Using intrinsic viscosity phenol / tetrachloroethane (weight ratio 1/1) as a solvent, a concentration of 500 mg / 50 ml and a temperature of 30
Hu determined separately from the specific viscosity measured under the condition of
Based on the ggins constant, Flory-Huggin
It was calculated by the s-Sakurada equation.

A test piece was prepared from the sheet having the obtained tensile strength and tensile elongation, and was subjected to JIS-K-63.
The tensile strength at break and tensile elongation at break were measured in accordance with No. 01. Flexural modulus The flexural modulus was measured according to JIS-K-7206. Blow molding was performed by the above-described method, and the stability of the molding and the surface properties of the molded product were evaluated. ：: good moldability △: good moldability ×: not moldable

<Evaluation of Results> When the lithium carboxylate, which is an essential component of the present invention, is not contained (Comparative Examples 1 to 5 and 14 to 16), or when it is contained but not lithium salt (Comparative Example 6) And 7), the MFRs are all high, and the high molecular weight is not sufficiently achieved. Also, the hollow moldability is inferior. When the content is insufficient (Comparative Example 18), the molecular weight is improved as compared with the case where the content is not included, but the degree is insufficient. Furthermore, when the epoxy compound is used only in an amount less than the range of the present invention (Comparative Examples 8 to 10) and when the epoxy compound is bifunctional (Comparative Examples 11 to 13), the melt flow rate is low. As is evident from the values, the expected increase in molecular weight has not occurred. When this was used in excess (Comparative Example 17), the result was that the hollow moldability was also poor, probably because the molecular weight was too high and the elongation was insufficient.

That is, good results can be obtained only by melt-kneading a mixture containing the specific polyester-based block copolymer of the present invention, the specific epoxy compound and the lithium carboxylate in a specific composition ratio, That is, it is apparent that an increase in molecular weight and excellent moldability and physical properties of a molded article can be obtained.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

By using the method of the present invention, it is possible to increase the viscosity of the polyester-based block copolymer by melt-kneading, and to obtain a polyester-based block copolymer having excellent hollow moldability and mechanical properties such as tensile strength and impact strength. An elastomer can be obtained.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Minoru Kishishita 1 Tohocho, Yokkaichi-shi, Mie Mitsubishi Chemical Corporation Yokkaichi Office (72) Inventor Kazunori Yano 1 Tohocho, Yokkaichi-shi, Mie Mitsubishi Chemical Corporation F-term (reference) at Yokkaichi Office 4J002 CD012 CD022 CD042 CD062 CD132 CD162 CF101 EG026 EG056 EG076 EG106 FD010 4J029 AA03 AB04 AC03 AE01 BA02 BA03 BA04 BA05 BA08 BB08A BB10A BD04A BD07A BF25 BF27 CB27 CCB CB27 CB27 CCB CC KD02 KD17 KH01 LB05

Claims (7)

[Claims] 1. A polyester block copolymer containing a block of polyalkylene ether glycol, 0.1 to 4 parts by weight of a trifunctional or more functional epoxy compound per 100 parts by weight of the copolymer, and 0.05 to A method for producing a polyester elastomer, comprising melt-kneading a composition containing 3 parts by weight of a lithium carboxylate. 2. The method for producing a polyester elastomer according to claim 1, wherein the number average molecular weight of the block portion of the polyalkylene ether glycol of the polyester block copolymer is from 400 to 6,000. 3. The polyester block copolymer is obtained from a dicarboxylic acid mainly composed of terephthalic acid or an ester-forming derivative thereof, a low molecular weight glycol or an ester-forming derivative thereof, and a polyalkylene ether glycol. 3. The method for producing a polyester elastomer according to 1 or 2. 4. The method for producing a polyester elastomer according to claim 1, wherein the epoxy compound is a 3- to 15-functional epoxy compound. 5. The method according to claim 1, wherein the polyalkylene ether glycol is polytetramethylene ether glycol.
5. The method for producing the polyester elastomer according to any one of the above items 4. 6. The lithium carboxylate having 2 to 2 carbon atoms.
A lithium salt of an aliphatic carboxylic acid of 50.
The method for producing a polyester elastomer according to any one of the above. 7. The method according to claim 1, wherein the melt-kneading is performed using a single-screw or twin-screw extruder at a temperature of 160 to 300 ° C. and an average residence time of 6 seconds to 60 minutes. A method for producing a polyester elastomer.