JPH05140433A - Molded tubular article oil-resistant at high temperature and cover boot - Google Patents

Abstract

PURPOSE:To prepare a molded tubular article excellent in oil resistance at high temp. and in flexibility by molding a compsn. contg. a specific polyester and a polycarbodiimide into a tube. CONSTITUTION:A molded tubular article is prepd. by molding a compsn. prepd. by compounding 0.3-5.0 pts.wt. polycarbodiimide into 100 pts.wt. polyester which is prepd. from an aliph. dicarboxylic acid of formula I, an aliph. diol, a dihydroxy compd. of formula II, and at least one monohydroxy compd. of formula III, contains 2-10mol.% units derived from the dihydroxy compd. and/or the monohydroxy compd., and has an intrinsic viscosity at 30 deg. in o-chlorophenol of 0.8-3.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastomeric tubular molding and a cover boot which have excellent flexibility and oil resistance even at high temperatures.

[0002]

2. Description of the Related Art Elastomeric tubular moldings represented by hoses and tubes are used in many fields such as daily necessities, automobiles and machines. On the other hand, a cover boot having a bellows shape is used for a suspension of an automobile, a motorcycle, or the like.
It is used to protect the drive parts such as the steering and the drive system, and specific examples thereof include constant velocity joint boots, rack and pinion boots, strut suspension boots and the like. Up to now, rubber such as chloroprene has been used as a material for these tubular molded bodies or cover boots, but since rubber is inferior in heat resistance, in recent years, it has been excellent in heat resistance and flexibility, and is easily heat-molded. Plastic elastomers are beginning to be used. Among various thermoplastic elastomers, a polyester-based elastomer having excellent heat resistance is being studied as a member to be used in a part where heat resistance is required.

By the way, in the drive section in which the tubular molded body and the cover boot are used, hydraulic oil such as grease is often used in order to improve the operability. Adheres. Therefore, the tubular molded body and the cover boot are required to have oil resistance in addition to heat resistance. The above-mentioned polyester-based elastomer has a drawback that when the working oil adheres, the working oil absorbs the working oil and swells, so that the physical properties are remarkably deteriorated. Therefore, a material having excellent oil resistance is required, and various attempts have been made.

For example, in JP-A-64-87973, a base layer is formed by using a polyester elastomer, and a coating layer is formed on the surface by using a polyurethane elastomer, so that the hydraulic oil contacts the base layer. A cover boot that prevents the occurrence of heat is disclosed. However, in this publication, the oil resistance of the polyester elastomer itself is not improved.

The heat resistance and oil resistance of thermoplastic elastomers are largely dependent on the strength of physical crosslinks formed by agglomeration of hard segments in the elastomer. Conventionally,
In order to obtain an elastomer excellent in oil resistance under high temperature (oil resistance at high temperature), the content of the hard segment was increased, but the elastomer obtained by this is
It has the disadvantage of poor flexibility. Therefore, even if this is molded, the above-mentioned tubular molded body and cover boot having good flexibility cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks, and an object thereof is to provide a tubular molded article and a cover boot which are excellent in flexibility and oil resistance at high temperature. ..

[0007]

The tubular molded article of the present invention comprises:
At least an aliphatic dicarboxylic acid represented by the following general formula [I], an aliphatic diol, and a dihydroxy compound represented by the following general formula [II] and a monohydroxy compound represented by the following general formula [III] One kind as a constituent component, the dihydroxy compound [II] and / or the monohydroxy compound [III] is contained in an amount of 2 to 10 mol% based on all monomers constituting the polyester, and O-
In 100 parts by weight of polyester having an intrinsic viscosity of 0.8 to 3.0 measured at 30 ° C. in chlorophenol,
It is molded from a polyester composition containing 0.3 to 5.0 parts by weight of polycarbodiimide, whereby the above object is achieved.

[0008]

[Chemical 4]

(In the formula, n represents an integer of 0 to 10).

[0010]

[Chemical 5]

(In the formula, R ¹ and R ² each independently represent an alkylene group, p is 3 or 4, and q and r each independently represent 0 or an integer of 1 or more).

[0012]

[Chemical 6]

(In the formula, R ³ represents an alkylene group, t is 2 or 3, and m represents an integer of 0 or 1 or more).

The cover boot of the present invention is molded from the polyester composition used in the above-mentioned tubular molded body, and has a bellows portion in at least a part thereof, thereby achieving the above object.

The aliphatic dicarboxylic acid which is a constituent of the polyester used in the polyester composition used in the present invention is represented by the following general formula [I].

[0016]

[Chemical 7]

(In the formula, n represents an integer of 0 to 10).

As such a compound, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid and sebacic acid are preferably used. When a dicarboxylic acid having a carbon number n of more than 10 is used, various physical properties of a molded product using the obtained polyester are inferior.

Examples of the aliphatic diol which is a constituent component of the polyester contained in the polyester composition used in the present invention include glycol and polyalkylene oxide shown below.

Examples of the glycol include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7. -Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,3
-Diol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol and the like can be mentioned, and these may be used alone or in combination of two or more kinds.

Examples of the above-mentioned polyalkylene oxide include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polyhexamethylene oxide, etc. These may be used alone or in combination of two or more kinds. Good. The number average molecular weight of the polyalkylene oxide is preferably 100 to 20,000, more preferably 500 to 5,000. When the number average molecular weight is less than 100, the resulting aromatic polyester has insufficient flexibility, and when the number average molecular weight exceeds 20,000, the resulting aromatic polyester has poor physical properties such as thermal stability.

The dihydroxy compound which is a constituent of the polyester contained in the polyester composition used in the present invention is represented by the following general formula [II].

[0023]

[Chemical 8]

(In the formula, R ¹ and R ² each independently represent an alkylene group, p is 3 or 4, and q and r each independently represent 0 or an integer of 1 or more).

In the above formula [II], the alkylene group R ¹
And R ² is preferably an ethylene group or a propylene group, and q and r are preferably 0 or 1. For example,
4,4 "-dihydroxy-p-terphenyl represented by the following formula [A], 4,4"'-dihydroxy-p-quaterphenyl represented by the following formula [B], represented by the following formula [C] 4,4 ′ ″-di (2-hydroxyethoxy) -p-quaterphenyl and the like are preferably used.

[0026]

[Chemical 9]

[0027]

[Chemical 10]

[0028]

[Chemical 11]

These compounds can be produced by a known method. For example, 4,4 ′ ″-dihydroxy-p-quaterphenyl [B] is a compound of Journal of C.
It can be synthesized according to the method described in hemical Society, 1379-85 (1940).

The dihydroxy compounds [II] may be used alone or in combination of two or more.

The above compounds have high crystallinity and high melting points. For example, the melting point of 4,4 ″ -dihydroxy-p-terphenyl [A] is 260 ° C., and that of 4,4 ′ ″-dihydroxy-p-quaterphenyl [B] is 336 ° C.
And 4,4 ″ ′-di (2-hydroxyethoxy)-
That of p-quaterphenyl [C] is 403 ° C. Therefore, when these dihydroxy compounds [II] are incorporated in the polymer chain, the polymer has properties of high flexibility and high heat resistance and oil resistance. In other words, in this polymer, the component derived from the dihydroxy compound [II] exhibits crystallinity and its melting point is high, so even if the amount of the dihydroxy compound [II] is small, this portion is strong and heat resistant. It becomes a highly hard segment, which forms physical crosslinks in the polymer. As a result, it is presumed that a thermoplastic elastomer having high heat resistance and oil resistance, that is, a thermoplastic elastomer excellent in high temperature oil resistance can be obtained without impairing the flexibility derived from the soft segment.

The monohydroxy compound used in place of the dihydroxy compound or together with the dihydroxy compound is a rigid low-molecular compound represented by the following general formula [III] and having a paraphenylene skeleton.

[0033]

[Chemical 12]

(In the formula, R ³ is an alkylene group, t is 2 or 3, and m is 0 or an integer of 1 or more).

This compound has an extremely high melting point, reflecting its characteristic molecular structure. Therefore, when the monohydroxy compound [III] is incorporated into the polymer chain, a very strong physical crosslink is formed, and as a result, the high temperature oil resistance of the polymer is increased.

In the monohydroxy compound represented by the above general formula [III], R ³ is preferably an ethylene group or a propylene group, and m is preferably 0 or 1. Examples of the monohydroxy compound [III] include 4-hydroxy-p-terphenyl and 4
-Hydroxy-p-quaterphenyl, 4- (2-hydroxyethoxy) -p-terphenyl, 4- (2-hydroxyethoxy) -p-quaterphenyl and the like can be mentioned. The above monohydroxy compounds [III] may be used alone or in combination.

In addition to the above aliphatic dicarboxylic acid [I], aliphatic diol, and dihydroxy compound [II] and / or monohydroxy compound [III], a polysilicone having two hydroxyl groups, a lactone, an aromatic hydroxycarboxylic acid Acids may be used as a constituent of the above polyesters.

Further, the polyester may contain an aromatic diol or aromatic dicarboxylic acid other than the dihydroxy compound [II] as a constituent component in order to improve the mechanical properties of the polyester.

The above-mentioned polysilicone is a silicone having a siloxane bond and has two hydroxyl groups.
These two hydroxyl groups are preferably at the terminal of the molecule,
For example, dimethylpolysiloxane, diethylpolysiloxane, diphenylpolysiloxane, etc., each having one hydroxyl group at each end of the molecule, may be mentioned. The number average molecular weight of the polysilicone is preferably 100 to 20,000,
It is more preferably 500 to 5000. When the number average molecular weight is less than 100, the flexibility of the aromatic polyester produced is insufficient, and when it exceeds 20,000, it becomes difficult to produce the aromatic polyester.

The lactone has the property of ring-opening and reacting with the carboxyl group and hydroxyl group of the aromatic polyester to add an aliphatic chain. As such a lactone, a lactone having 4 or more carbon atoms in the ring is preferably used, and a 5-membered to 8-membered ring is more preferable. For example, ε-caprolactone, δ-valerolactone, γ-butyrolactone and the like can be mentioned.

Examples of the aromatic hydroxycarboxylic acid include salicylic acid, metahydroxybenzoic acid, parahydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, 3-bromo-4-hydroxybenzoic acid and 3-methoxy-. 4-hydroxybenzoic acid, 3-methyl-4-hydroxybenzoic acid, 3-phenyl-4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 4-hydroxy-4′-carboxybiphenyl and the like can be mentioned, preferably. Is para-hydroxybenzoic acid, 2-hydroxy-6
-Naphthoic acid, 4-hydroxy-4'-carboxybiphenyl and the like are used.

Examples of the aromatic diol include hydroquinone, resorcin, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, bisphenol A, 1,1-di (4-hydroxyphenyl) cyclohexane, 1,2-bis (4-hydroxyphenoxy) ethane, 1,4-dihydroxynaphthalene, 2,6
-Dihydroxynaphthalene and the like.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, metal salts of 5-sulfoisophthalic acid, 4,4'-dicarboxybiphenyl,
4,4'-dicarboxydiphenyl ether, 4,4 '
-Dicarboxydiphenyl sulfide, 4,4'-dicarboxydiphenyl sulfone, 3,3'-dicarboxybenzophenone, 4,4'-dicarboxybenzophenone, 1,2-bis (4-carboxyphenoxy) ethane, 1,4 -Dicarboxynaphthalene, 2,6-dicarboxynaphthalene and the like.

Next, the contents of the above respective constituents in the polyester will be described.

The polyester contained in the polyester composition used in the present invention is an aliphatic carboxylic acid [I],
When it is composed of an aliphatic diol and a dihydroxy compound [II], the content of the dihydroxy compound [II] is 2.0 to 10 mol% with respect to all the monomers constituting the polyester. Dihydroxy compound [II]
When the content of (1) is low, the high temperature oil resistance of the resulting polyester is low, and when it is high, the elastic modulus is high and the flexibility is low, so that it is unsuitable as a thermoplastic elastomer.

When the polyester is composed of an aliphatic carboxylic acid [I], an aliphatic diol, and a monohydroxy compound [III], the content of the monohydroxy compound [III] is the total amount of all monomers constituting the polyester. To 2.0 to 10 mol%. When the amount of the monohydroxy compound [III] decreases, the high temperature oil resistance of the resulting polyester decreases, and when the amount of the monohydroxy compound [III] increases, the molecular weight of the polyester does not become sufficiently high and the physical properties deteriorate.

When the polyester contains both the dihydroxy compound [II] and the monohydroxy compound [III], the content of the hydroxy compound including the dihydroxy compound [II] and the monohydroxy compound [III] Is preferably 2.0 to 10 mol% with respect to all monomers constituting the polyester. When the content of these hydroxy compounds is low, the high temperature oil resistance of the produced polyester is poor, and when it is too high, the flexibility of the produced polyester is insufficient and the molecular weight is not sufficiently high. The content ratio of the monohydroxy compound [III] to the total amount of the dihydroxy compound [II] and the monohydroxy compound [III] in the polyester satisfies 0 <[III] / [II] + [III] <2/3 It is preferably in the range.

When the polyalkylene oxide or the polysilicone is used as the constituent component of the polyester, the constituent unit is counted as one monomer.
That is, polyethylene oxide having a degree of polymerization of 10 is counted as 10 monomers.

The polyester having the above-mentioned components and contained in the polyester composition used in the present invention can be produced by any generally known polycondensation method. For example, a method of directly reacting a dicarboxylic acid component with a diol component, a method of reacting a lower ester of dicarboxylic acid with a diol component by transesterification, and a method of reacting a dicarboxylic acid halide and a diol component with pyridine or the like Examples thereof include a method of reacting in a solvent, a method of reacting a metal alcoholate of a diol component with a halide of a dicarboxylic acid, and a method of reacting an acetylated product of a diol component with a dicarboxylic acid by transesterification.

In the polycondensation, a catalyst generally used in producing polyester may be used. As the catalyst, lithium, sodium, potassium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, cerium, boron, cadmium, manganese, and other metals, Examples thereof include organic metal compounds, organic acid salts, metal alkoxides and metal oxides.

Particularly preferred catalysts are calcium acetate, diacyl stannous tin, tetraacyl stannic tin, dibutyltin oxide, dibutyltin dilaurate, dimethyltin malate,
Examples include tin dioctanoate, tin tetraacetate, triisobutylaluminum, tetrabutyl titanate, germanium dioxide and antimony trioxide. You may use together 2 or more types of these catalysts.

Further, in order to improve thermal stability during polymerization,
The following hindered phenolic antioxidants and heat stabilizers may be used.

Examples of the hindered phenolic antioxidant include 1,3,5, -trimethyl-2,4,4.
6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,9-bis [2- [3- (3-
t-butyl-4-hydroxy-5-methylphenyl)-
Propionyloxy] -1,1-dimethylethyl] 2,
4,8,10-tetraoxaspiro [5,5] undecane and the like can be mentioned.

Examples of the heat stabilizer include tris (2,4-di-t-butylphenyl) phosphite, trilaurylphosphite, 2-tert-butyl-α-.
(3-tert-butyl-4-hydroxyphenyl)-
p-cumenylbis (p-nonylphenyl) phosphite, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, pentaerythylyltetrakis (3-laurylthiopropionate), etc. Can be mentioned.

During the reaction, water, alcohol, glycol and the like, which are by-products of the polymerization, are efficiently distilled off to obtain a polyester having a high molecular weight.
It is preferable to reduce the pressure to mmHg or less. The reaction temperature is generally 150 to 350 ° C.

When a dihydroxy compound [II] is used as a constituent component of the above polyester, the structure of the obtained polyester is changed by changing the time of adding the dihydroxy compound [II] to the reaction system during the polymerization reaction. It is possible to change. For example, when the dihydroxy compound [II] is charged together with the dicarboxylic acid and other diol components, a random copolymer is easily obtained. When the dihydroxy compound [II] is added to the reaction system in the latter stage of polymerization, a block copolymer is easily obtained. Dihydroxy compound [II] or an acetyl compound of dihydroxy compound [II] was melt-kneaded with polyester obtained by polymerizing a dicarboxylic acid and another diol component in advance and deethylene glycol It is also possible to introduce a segment based on the dihydroxy compound [II] into the molecular chain of the polyester by reaction or transesterification reaction.

The intrinsic viscosity [η] (measured in O-phenol at 30 ° C.) of the polyester obtained as described above is
It is 0.8 to 3.0, and particularly preferably 0.8 to 2.0. When polyester less than 0.8 is used, the heat resistance and mechanical properties of the composition containing the polyester are inferior, and when polyester more than 3.0 is used, the composition is molded. Becomes difficult.

The polyester composition used in the present invention is obtained by reacting the polyester obtained as described above with a polycarbodiimide. By including the polycarbodiimide in the polyester composition, the heat resistance of the polyester composition is improved, and the molecular weight does not decrease even when the molded product is used at high temperature. It is presumed that this is because polycarbodiimide reacts with the carboxyl group at the terminal of the polyester to seal it or to extend the molecular chain by connecting two molecules of polyester, so that the decrease in molecular weight is suppressed. Such a polycarbodiimide is a polycarbodiimide having an average of two or more carbodiimide groups per molecule, and may be aliphatic, alicyclic or aromatic. For example, poly (tolylcarbodiimide), poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (1,3,5-triisopropylphenylene-2,4)
-Carbodiimide) and the like. The above carbodiimide may be used in combination of two or more kinds.

The carbodiimide is added in an amount of 0.3 to 5.0 parts by weight based on 100 parts by weight of the polyester. If the blending amount is less than 0.3 parts by weight, a polyester composition having sufficient heat resistance cannot be obtained,
When the amount is more than the amount by weight, the physical properties of the polyester composition are poor.

The following additives may be added to the polyester composition used in the present invention within the range not impairing the practical use: (i) Inorganic fiber: glass fiber, carbon fiber, boron fiber, carbonization Silicon fiber, alumina fiber, amorphous fiber, silicone / titanium / carbon fiber, etc. (ii) Organic fiber: aramid fiber, etc. (iii) Inorganic filler: calcium carbonate, titanium oxide, mica, talc, etc. (iv) Heat Stabilizers: triphenyl phosphite, trilauryl phosphite, trisnonyl phenyl phosphite,
2-tert-butyl-α- (3-tert-butyl-
4-hydroxyphenyl) -p-cumenylbis (p-nonylphenyl) phosphite, etc. (v) Flame retardant: hexabromocyclododecane, tris-
(2,3-dichloropropyl) phosphate, pentabromophenylallyl ether, etc. (vi) UV absorber: p-tert-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2 '-Carboxybenzophenone, 2,4,5-trihydroxybutyrophenone, etc. (vii) Antistatic agent: N, N-bis (hydroxyethyl)
(Viii) Inorganic powder: barium sulfate, alumina, silicon oxide, etc. (ix) Antioxidants: butylhydroxyanisole, butylhydroxytoluene, disterarylallylthiodipropionate, etc. , Dilauryl thiodipropionate, hindered phenolic antioxidants, etc.

Further, the polyester composition used in the tubular molded article of the present invention is mixed with another thermoplastic resin such as polyurethane, polyolefin, modified polyolefin, polystyrene, polyamide, polycarbonate, polysulfone, polyester, or a rubber component. By doing so, it is possible to modify the properties of the polyester composition.

In order to mix the above-mentioned polyester, polycarbodiimide and, if necessary, the respective components of the above-mentioned various additives, a known method capable of uniformly mixing the resin can be used. For example, it can be carried out by a melt-kneading method using a plastomill, an extruder, a kneader, a Banbury mixer, or the like.

As a method for molding the polyester composition of the present invention to obtain a tubular molded body such as a hose or a tube, a molding method such as extrusion molding, injection molding or blow molding can be used.

The cover boot of the present invention is obtained by molding the same polyester composition as the above-mentioned tubular molded body.

FIG. 1 is a side view of the cover boot of the present invention. The cover boot 1 is a molded body having a bellows portion 2 in a part thereof. The cover boot 1 may be entirely formed of the bellows portion 2.

As a method for molding the above polyester composition to obtain the cover boot 1 of the present invention, for example, the method mentioned as the method for obtaining the above-mentioned tubular molded body can be mentioned. Extrusion using an extrusion blow molding machine is possible. The molding method is preferred.

[0067]

EXAMPLES The present invention will be described below based on examples.

(1) Synthesis of Polyester (a) Synthesis of Polyester-1 2925 g (20 mol) of adipic acid, 2980 g (48 mol) of ethylene glycol and 4,4 ″ ′-dihydroxy-p-quaterphenyl (hereinafter referred to as DHQ ) 677 g (2 mol) of the monomer mixture, 2 g of germanium dioxide as a catalyst and 1,3,5 as a stabilizer
-Trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene 4 g and tris (2,4-di-t-butylphenyl) phosphite 4 g were added and the reaction system was heated under nitrogen to give 200
The temperature was kept at 2 ° C for 2 hours to carry out the esterification reaction. Then, the reaction system is heated to 320 ° C. in 30 minutes, and at this temperature, 2
It was kept at normal pressure for 0 minutes. After that, lower the temperature to 300 ° C and
As a result of carrying out a polycondensation reaction for 2 hours under a reduced pressure of mmHg or less, light yellow polyester-1 was obtained.

Intrinsic viscosity [η] of this polyester-1
Was measured by the following method.

Measurement of Intrinsic Viscosity [η] Using an Ubbelohde viscometer, the viscosity was measured at 30 ° C. in an o-chlorophenol solvent.

The intrinsic viscosity of polyester-1 is 1.10.
Shore D hardness was 34.

(B) Synthesis of Polyester-2 Except that DHQ was 508 g (1.5 mol).
Polyester-2 was obtained in the same manner as in (1)-(a).

The intrinsic viscosity of polyester-2 is 1.20,
Shore D hardness was 28.

(C) Synthesis of Polyester-3 Except that DHQ was 169 g (0.5 mol),
Polyester-3 was obtained in the same manner as in (1)-(a).

The intrinsic viscosity of polyester-3 is 0.98,
Shore D hardness was 38.

(D) Synthesis of Polyester-4 (1) except that the reaction system was cooled to 300 ° C. and the polycondensation reaction was carried out for 1 hour after the pressure was reduced to 1 mmHg.
Polyester-4 was obtained in the same manner as in the item (a).

The intrinsic viscosity of polyester-4 is 0.73,
Shore D hardness was 33.

(2) Preparation of polyester composition and molding of tubular molding (Example 1) Polyester-1100 obtained in paragraphs (1)-(a)
In parts by weight, 3,9-bis [2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) -propionyloxy] was used as a hindered phenol antioxidant.
0.2 parts by weight of 1,1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane and pentaerythyryltetrakis (3-laurylthiopropionate 0. 32 parts by weight and 2 parts by weight of poly (1,3,5-triisopropylphenylene-2,4-carbodiimide) (Stavaxol P-100 manufactured by Sumitomo Bayer Urethane Co., Ltd.) as a polycarbodiimide were added, and Brabender Plastograph was added. An extruded resin composition was obtained at 240 ° C. using an extruder.

The resin composition was extruded using a uniaxial extruder with a hose mold having an inner diameter of 10 mm and an outer diameter of 14 mm to form a hose. Molding temperature is 240 ℃ for the mold,
The cylinder part was 235-240 degreeC.

This hose was cut to a length of 20 cm and
No. S3 oil was filled in the hose, the openings at both ends of the hose were sealed with silicone stoppers, and the hose was allowed to stand in a gear oven at 120 ° C. After 30 days, the hose was cooled to room temperature, drained of oil, and then bent at 90 degrees, but the hose did not crack and maintained good flexibility.

Example 2 A resin composition was obtained in the same manner as in Example 1 except that the polycarbodiimide content was 1 part by weight, and the molded hose was tested. After the test, the hose did not crack and maintained good flexibility.

Example 3 A resin composition was obtained in the same manner as in Example 1 except that polyester-2 was used, and the molded hose was tested. After the test, the hose did not crack and maintained good flexibility.

Comparative Example 1 A test was conducted in the same manner as in Example 1 except that polycarbodiimide was not added. After the test, the hose had numerous cracks.

(Comparative Example 2) A test was conducted in the same manner as in Example 1 except that Polyester-3 was used. After the test, the hose had numerous cracks.

(Comparative Example 3) A test was conducted in the same manner as in Example 1 except that Polyester-4 was used. After the test, the hose had numerous cracks.

(3) Molding of cover boot (Example 4) Using the resin composition obtained in Example 1 and using an extrusion blow molding machine, as shown in FIG. The cover boot 1 was molded. In FIG. 1, the outer diameter H ₁ was 93 mm and the outer diameter H ₂ was 30 mm.
The outer diameter of the maximum peak of the bellows part 2 was 105 mm, the outer diameter of the minimum peak was 70 mm, the outer diameter of the maximum trough was 72 mm, and the outer diameter of the minimum trough was 50 mm. The average thickness of the cover boot 1 was 1.3 mm.

This cover boot 1 was heated at 120 ° C. for 14
It was immersed in JIS No. 3 oil for a day. After the immersion, the surface hardness was measured. The results are shown in Table 1 below. Example 5 described later
Results of Example 6 and Comparative Examples 4 to 6 are also shown in Table 1.

Example 5 The procedure of Example 4 was repeated except that the resin composition obtained in Example 2 was used.

Example 6 The procedure of Example 4 was repeated except that the resin composition obtained in Example 3 was used.

Comparative Example 4 A test was performed in the same manner as in Example 4 except that the resin composition obtained in Comparative Example 1 was used.

Comparative Example 5 A test was performed in the same manner as in Example 4 except that the resin composition obtained in Comparative Example 2 was used.

Comparative Example 6 A test was conducted in the same manner as in Example 4 except that the resin composition obtained in Comparative Example 3 was used.

[0093]

[Table 1]

From Table 1, it can be seen that the cover boot of the present invention is remarkably improved in high temperature oil resistance.

[0095]

According to the present invention, it is possible to obtain a tubular molded body and a cover boot which are excellent in oil resistance at high temperature without impairing flexibility, and can be used as various members to be used in a machine part using working oil. It can be used preferably.

[Brief description of drawings]

FIG. 1 is a side view of a cover boot of the present invention.

[Explanation of symbols]

 1 cover boot 2 bellows

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroki Kakumachi, 1-11-3 Minamikasugaoka, Ibaraki-shi, Osaka (72) Inventor Daishiro Kishimoto 2--11-20, Mishimaoka, Ibaraki, Osaka

Claims (2)

[Claims] 1. An aliphatic dicarboxylic acid represented by the following general formula [I], an aliphatic diol, a dihydroxy compound represented by the following general formula [II] and the following general formula [III]:
At least one of the monohydroxy compounds represented by
2 to 10 mol% of the dihydroxy compound [II] and / or the monohydroxy compound [III] is contained in the O-chlorophenol at 30 ° C. in the O-chlorophenol. Polyester 10 having a measured intrinsic viscosity of 0.8 to 3.0
A tubular molded product molded from a polyester composition obtained by mixing 0.3 to 5.0 parts by weight of polycarbodiimide with 0 part by weight. [Chemical 1] (In the formula, n represents an integer of 0 to 10) (In the formula, R ¹ and R ² each independently represent an alkylene group, p is 3 or 4, and q and r each independently represent 0 or an integer of 1 or more.) (In the formula, R ³ represents an alkylene group, t is 2 or 3, and m is 0 or an integer of 1 or more.) 2. A cover boot molded from the polyester composition according to claim 1, which has a bellows part at least in part.