JP2002338698A - Thermoplastic elastomer composition, its manufacturing method and molded article using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition which can be melt molded and excels in mechanical strength, oil resistance, heat resistance, flexibility, and compression set, particularly a thermoplastic elastomer composition having excellent thermal aging resistance which can be used even in an application in which the composition is left to stand under high temperature conditions for a long period of time. SOLUTION: The thermoplastic elastomer composition is obtained by melt kneading (A) a thermoplastic polyester elastomer, (B) a chlorinated polyethylene having a crystal fusion calorific value of <=40 J/g and a chlorine content of 15-45 wt.%, and (C) a crossliking agent to effect dynamic crosslinking. Further, a molded article, particularly a joint boot is obtained by subjecting the thermoplastic elastomer composition to melt molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer composition obtained by melt-kneading a thermoplastic polyester elastomer, chlorinated polyethylene, and a crosslinking agent and dynamically crosslinking the same, and a method for producing the same. The present invention also relates to a molded product obtained by molding the same, particularly to a joint boot.

[0002]

2. Description of the Related Art Thermoplastic polyester elastomers are:
It is composed of a hard segment made of crystalline polyester and a soft segment made of a polymer having a lower melting point or glass transition point, and can be melt-molded, and has mechanical strength, heat resistance and oil resistance. Are better. However, as an elastomer, the hardness is high, the flexibility is inferior, and the compression set is relatively large,
At present, applications are limited.

[0003] Joints of automobiles and industrial machines are equipped with joint boots for holding the sealed grease and preventing dust from being mixed therein. Conventionally, such joint boots were made of a crosslinked rubber such as chloroprene rubber, but recently, a thermoplastic polyester elastomer having a higher strength than the crosslinked rubber has been used, and the weight has been reduced by reducing the wall thickness. I have. However, since the thermoplastic polyester elastomer has a large compression set, it is necessary to increase the tightening force of the metal fitting at the joint portion, and it is difficult to attach the joint boot because it is harder than the crosslinked rubber. In addition, since the heat aging resistance is not sufficient, it is difficult to use the parts exposed to high heat for a long period of time.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 5-125263 discloses a thermoplastic elastomer composition obtained by dynamically crosslinking a thermoplastic polyester elastomer and rubber during kneading. The composition is described as having improved flexibility and compression set, and is particularly suitable for automotive constant velocity joint boots. Although chlorinated polyethylene is described as one of a large number of rubber components to be blended, there is no description about the heat of crystal fusion or the chlorine content.

[0005] JP-A-3-21662 describes a resin composition comprising a thermoplastic polyester elastomer and chlorinated polyethylene. The resin composition,
It is described that it is excellent in thermal grease resistance and is useful as a constant speed boot in a front wheel drive vehicle. Japanese Patent Application Laid-Open No. 9-95578 discloses a thermoplastic polyester elastomer having a heat of crystal fusion of 5 to 35 cal / g (21
147 J / g) of a chlorinated polyethylene. It is described that in the resin composition, compression set is improved by using a specific crystalline chlorinated polyethylene. However, the resin compositions described in these publications are merely melt-blended thermoplastic polyester elastomers and chlorinated polyethylene, and there is no description of dynamic crosslinking, and heat resistance is poor. It was sufficient, and the improvement of compression set at high temperature was insufficient.

[0006]

As described above, although a method for improving flexibility and compression set while maintaining the mechanical strength, heat resistance and oil resistance of a thermoplastic polyester elastomer has been proposed, Its performance is still unsatisfactory, and particularly its heat aging resistance is not sufficient. The present invention is intended to solve such a problem, and provides a thermoplastic elastomer composition which is melt-moldable and has improved flexibility and compression set while maintaining mechanical strength and oil resistance. Things. In particular, an object of the present invention is to provide a thermoplastic elastomer composition excellent in compression set and heat aging resistance, which can be used even in an application under high temperature conditions for a long time. The present invention also provides a molded product obtained by molding the same, particularly a joint boot.

[0007]

The object of the present invention is to provide a thermoplastic polyester elastomer (A) having a heat of crystal fusion of 40.
Provided is a thermoplastic elastomer composition obtained by melt-kneading a chlorinated polyethylene (B) having J / g or less and a chlorine content of 15 to 45% by weight and a crosslinking agent (C) to dynamically crosslink. It is solved by. At this time, 30 to 99 parts by weight of the thermoplastic polyester elastomer (A) and 1 to 70 parts by weight of the chlorinated polyethylene (B) are added to 100 parts by weight of the total of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B). A thermoplastic elastomer composition obtained by blending 0.01 to 5 parts by weight of the crosslinking agent (C) and melt-kneading is preferred.

[0008] Thermoplastic polyester elastomer (A)
A thermoplastic elastomer composition obtained by mixing 0.1 to 20 parts by weight of the compatibilizer (D) with respect to 100 parts by weight of the total of the chlorinated polyethylene (B) and the melt-kneaded mixture is suitable. At this time, the compatibilizer (D) is a polymer containing an epoxy group, and the ratio of the weight of the oxygen element derived from the epoxy group contained in the compatibilizer (D) to the weight of the thermoplastic polyester elastomer (A) is as follows. 1/10000 to 5/10
00 is particularly preferred. Further, a thermoplastic elastomer composition obtained by blending 5 to 100 parts by weight of the basic substance (E) with respect to 100 parts by weight of the chlorinated polyethylene (B) and melt-kneading the mixture is also suitable.

In producing the above thermoplastic elastomer composition, the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) are melt-kneaded in advance, and then the crosslinking agent (C) is blended and further melt-kneaded. Is preferred. In particular, when the thermoplastic elastomer composition contains a basic substance (E), the chlorinated polyethylene (B) and the basic substance (E) are dry-blended or melt-blended in advance. Feed to extruder, thermoplastic polyester elastomer (A)
It is preferable to melt knead the mixture, then blend the crosslinking agent (C), and further melt knead the mixture.

In producing the thermoplastic elastomer composition, a twin-screw extruder is used when melt-kneading the thermoplastic polyester elastomer (A), the chlorinated polyethylene (B) and the crosslinking agent (C). The average temperature of the cylinder of the twin-screw extruder is set to 150 to 200 ° C., and the linear velocity around the screw is set to 5 to 25 m / min.
A manufacturing method of discharging a 30 ° C. molten resin is preferable. It is also preferable that the L / D of the screw of the twin-screw extruder used is 20 or more, and the ratio of the length of the kneading portion to the entire length of the screw is 2/100 to 30/100. .

[0011] The object of the present invention is also solved by providing a molded article obtained by melt-molding the above-mentioned thermoplastic elastomer composition. At this time, the tensile strength in the heat aging test in air at 150 ° C. was 20% after the start of the test.
It shows a local minimum between ~ 300 hours and then rises to 50
Molded articles that maintain a value of 50% or more of the tensile strength before the test after 0 hour are suitable.

A joint boot is a preferred embodiment of the molded article of the present invention. In this case, a joint boot that is arranged so as to cover the constant velocity joint on the engine side of the automobile is a particularly preferred embodiment.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermoplastic polyester elastomer (A), a chlorinated polyethylene (B) having a heat of crystal fusion of 40 J / g or less and a chlorine content of 15 to 45% by weight, It is a thermoplastic elastomer composition obtained by melt-kneading the agent (C) and dynamically crosslinking.

The thermoplastic polyester elastomer (A) used in the present invention is a block copolymer comprising a hard segment composed of a crystalline polyester and a soft segment composed of a polymer having a lower melting point or glass transition point. It is united. The soft segment not only has a lower melting point than the hard segment, but may not have a clear melting point in a DSC (differential scanning calorimeter) chart. In this case, the inflection derived from the glass transition point What is necessary is to observe a point.

[0015] Thermoplastic polyester elastomer (A)
As the crystalline polyester constituting the hard segment, an aromatic polyester composed of an aromatic dicarboxylic acid and an aliphatic diol is preferable. Particularly preferred aromatic dicarboxylic acid components are terephthalic acid and 2,6-naphthalenedicarboxylic acid. At this time, terephthalic acid or 2,
In addition to 6-naphthalenedicarboxylic acid, a small amount of another aromatic dicarboxylic acid such as isophthalic acid or an aliphatic dicarboxylic acid such as adipic acid, sebacic acid, cyclohexane-1,4-dicarboxylic acid or dimer acid may be used. . Examples of the aliphatic diol component forming the aromatic polyester include diols having 2 to 12 carbon atoms, such as ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanediol, and decanediol.

The lower limit of the melting point of the hard segment is 150
The temperature is preferably at least 170 ° C, more preferably at least 170 ° C, even more preferably at least 190 ° C. By setting such a lower limit, the heat resistance of the thermoplastic elastomer composition of the present invention is improved. On the other hand, the upper limit of the melting point of the hard segment is preferably 250 ° C. or less,
The temperature is more preferably 230 ° C or lower, and most preferably 210 ° C or lower. By setting such an upper limit, melt kneading at a relatively low temperature becomes possible, and thermal decomposition of the chlorinated polyethylene (B) during melt kneading can be prevented.

[0017] Thermoplastic polyester elastomer (A)
The soft segment is generally composed of a polymer having a lower melting point or glass transition point than the above-mentioned hard segment. Examples of the polymer constituting the soft segment include an aliphatic polyether and an aliphatic polyester.

Specific examples of the above-mentioned aliphatic polyether include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol block copolymer and the like. In particular, polytetramethylene glycol is flexible at low temperatures. Is preferred because it is good.

The aliphatic polyester is a polymer composed of an aliphatic dicarboxylic acid and an aliphatic diol, or a polymer composed of an aliphatic hydroxycarboxylic acid or a lactone. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, and decane dicarboxylic acid. In addition to the aliphatic dicarboxylic acid, a small amount of an aromatic dicarboxylic acid such as isophthalic acid may be used. Examples of the aliphatic diol include diols having 2 to 12 carbon atoms, such as ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanediol, and decanediol. The aliphatic polyester is obtained by polycondensing the aliphatic dicarboxylic acid and the aliphatic diol by a usual method, and may be a homopolyester or a copolymerized polyester, or may be obtained by ring-opening polymerization of a cyclic lactone. (Eg, poly-ε-caprolactone).

The upper limit of the melting point of the soft segment is not particularly limited as long as it is lower than that of the hard segment, but is preferably 100 ° C. or less, more preferably 50 ° C. or less, and still more preferably 0 ° C. or less. It is. Since the melting point of the soft segment is low, good rubber elasticity can be exhibited even in use in cold regions. The soft segment may be one in which a clear melting point is not observed in the DSC chart. In this case, it is preferable that the glass transition point is equal to or lower than a preferable upper limit of the melting point. The molecular weight of the soft segment is usually 400 to 6000.
It is about.

Thermoplastic polyester elastomer (A)
Inside hard segment (H) and soft segment (S)
Weight ratio (H / S) is preferably 40/6 by weight.
0 to 90/10. Hard segment weight 40
If the amount is less than% by weight, heat resistance and tensile strength may be insufficient. It is more preferably at least 40% by weight, even more preferably at least 55% by weight. If the proportion of the hard segment exceeds 90% by weight, the flexibility may be insufficient. It is more preferably at most 80% by weight, even more preferably at most 70% by weight.

Thermoplastic polyester elastomer (A)
Is particularly preferably used as a hard segment, using polytetramethylene terephthalate or polybutylene terephthalate / 2,6-naphthalate,
Polyether such as polytetramethylene glycol, polybutylene adipate, poly-ε as a soft segment
-It is formed using a polyester such as caprolactone. Among them, those using polybutylene terephthalate as the hard segment are suitable because the temperature at the time of dynamic crosslinking by melt-kneading with chlorinated polyethylene (B) is not too high and the crystallization speed is high. On the other hand, those using polytetramethylene glycol as the soft segment are preferable because of their good flexibility at low temperatures. That is, a thermoplastic polyester elastomer using polybutylene terephthalate as a hard segment and polytetramethylene glycol as a soft segment is optimal.

Further, a polycarboxylic acid, a polyfunctional hydroxy compound, an oxyacid or the like may be copolymerized as a part of the dicarboxylic acid or the diol. These polyfunctional components effectively act as high-viscosity components by copolymerizing in a range of 3 mol% or less. Examples of the polyfunctional component include trimellitic acid, trimesic acid, pyromellitic acid, benzophenonetetracarboxylic acid, butanetetracarboxylic acid, glycerin, pentaerythritol, or esters or acid anhydrides thereof.

Thermoplastic polyester elastomer (A)
Although the method for producing is not particularly limited, preferred polymerization methods include (1) an aromatic dicarboxylic acid or a dimethyl ester thereof, a low molecular weight diol, and a polyol constituting a soft segment in the presence of a catalyst. 150-26
A method of obtaining a thermoplastic elastomer by heating to 0 ° C., performing an esterification reaction or a transesterification reaction, and then proceeding a polycondensation reaction while removing excess low-molecular diol under vacuum, (2) previously prepared The high-melting-point polyester segment-forming prepolymer and the low-melting-point polymer segment-forming prepolymer are mixed with a bifunctional chain extender that reacts with the terminal group of the prepolymer and reacted. A method of obtaining a thermoplastic polyester elastomer by removing the volatile components while maintaining a vacuum, (3) by heat-mixing a high-melting polyester with a high degree of polymerization and a lactone, and subjecting the lactone to ring-opening polymerization and transesterification. And a method of obtaining a thermoplastic polyester elastomer.

The chlorinated polyethylene (B) used in the present invention has a heat of crystal fusion of 40 J / g or less and a chlorine content of 15 to 45% by weight.

The chlorinated polyethylene (B) is obtained by chlorinating polyethylene and has a chlorine content of 15 to 45% by weight. When the chlorine content is less than 15% by weight, the thermoplastic elastomer composition of the present invention has insufficient oil resistance. For example, grease or oil mist,
In particular, the lower limit of the chlorine content is important when used in applications that come into contact with high-temperature grease or oil mist, and is preferably at least 20% by weight, more preferably at least 25% by weight. On the other hand, when the chlorine content exceeds 45% by weight, the molecular weight distribution tends to decrease, and at the same time, the crystallinity increases. It is preferably at most 40% by weight, more preferably 3% by weight.
5% by weight or less.

The chlorinated polyethylene (B) used in the present invention has a heat of crystal fusion of 40 J / g or less. The heat of crystal fusion referred to here is a value measured by a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min.
The value calculated from the crystal peak area of the C chart. When the heat of crystal fusion exceeds 40 J / g, that is, when a large amount of polyethylene crystals remain after chlorination, the crosslinking reaction does not proceed sufficiently, so that the compression set becomes large. Especially when used at high temperatures. In addition, insufficient cross-linking deteriorates oil resistance and heat aging resistance. The heat of crystal fusion is preferably 30 J / g or less,
More preferably, it is 20 J / g or less. The chlorinated polyethylene (B) used may be one having no peak on the DSC chart, that is, one having a heat of crystal fusion of 0 J / g.

The chlorinated polyethylene (B) used in the present invention has the following properties based on the conditions of JIS K-7210.
The melt flow rate (MFR) measured at 80 ° C. under a load of 21.6 kgf (212 N) is 0.1 to 100 g /
It is preferable to use one for 10 minutes because it can be dispersed well with the thermoplastic polyester elastomer (A). MF
If R is less than 0.1 g / 10 minutes, the mechanical strength often decreases. It is more preferably at least 0.2 g / 10 min, and even more preferably at least 1 g / 10 min. On the other hand, M
When the FR is smaller than 100 g / 10 minutes, the processability is inferior and is not preferable. More preferably, it is 20 g / 10 minutes or less,
More preferably, it is 10 g / 10 minutes or less.

The thermoplastic elastomer composition of the present invention comprises:
For a total of 100 parts by weight of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B), 30 to 99 parts by weight of the thermoplastic polyester elastomer (A),
Those obtained by blending 1 to 70 parts by weight of the chlorinated polyethylene (B) are preferable. When the blending amount of the thermoplastic polyester elastomer (A) is less than 30 parts by weight, the heat resistance is not sufficient, and the melt moldability decreases. More preferably, the blending amount of the thermoplastic polyester elastomer (A) is at least 50 parts by weight, and even more preferably at least 70 parts by weight. On the other hand, when the blending amount of the thermoplastic polyester elastomer (A) exceeds 99 parts by weight, the flexibility of the obtained thermoplastic elastomer composition is not sufficient,
The heat aging resistance is also insufficient. It is more preferably at most 95 parts by weight, and even more preferably at most 90 parts by weight.

The crosslinking agent (C) used in the present invention is not particularly limited as long as it can crosslink chlorinated polyethylene. Examples include a triazine compound, an organic peroxide compound, a polyamine compound, sulfur, a thiadiazole compound, an alkylphenol resin, and a bis azidoformate compound. Among these, a triazine compound and an organic peroxide are preferable, and a triazine compound, particularly a mercaptotriazine compound, is optimal. Suitable mercaptotriazine compounds include, for example,
4,6-trimercapto-1,3,5-triazine is exemplified.

The amount of the crosslinking agent (C) to be blended is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the total of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B). If the amount is less than 0.01 part by weight, the crosslinking reaction does not sufficiently proceed, and sufficient heat resistance is often not obtained. It is more preferably at least 0.02 parts by weight, even more preferably at least 0.05 parts by weight. On the other hand, if it exceeds 5 parts by weight,
The crosslinking reaction proceeds excessively, the hardness becomes too high, and the rubber elasticity may be lost. More preferably not more than 2 parts by weight,
More preferably, the amount is 1 part by weight or less.

It is preferable to use a crosslinking aid together with the crosslinking agent (C) in order to efficiently promote a crosslinking reaction. The crosslinking aid is a crosslinking accelerator used in combination with the crosslinking agent (C), for example, a polyfunctional compound, a thiourea compound, a thiuram compound, a sulfenamide compound, a dithiocarbamic acid compound, a thiazole compound. And guadinine-based compounds. Specific examples of the polyfunctional compound include triallyl isocyanurate, triallyl cyanurate, metaphenylene bismaleimide, quinone dioxime, diallyl phthalate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, and the like. Is mentioned.

Among these, a thiazole compound or a sulfenamide compound is preferable as a crosslinking aid when a triazine compound is used as the crosslinking agent (C), and a thiazole compound or a sulfenamide compound is preferable when an organic peroxide is used as the crosslinking agent (C). As the crosslinking aid, triallyl isocyanurate or triallyl cyanurate is preferred. A particularly preferred combination is a combination using a mercaptotriazine-based compound as the crosslinking agent (C) and a thiazole-based compound as the crosslinking aid. Examples of the thiazole compound used include 2-mercaptobenzothiazole and 2,5-dimercaptobenzothiazole. The thiazole compound may be incorporated in the form of a salt, for example, a dicyclohexylamine salt.

The amount of the crosslinking aid to be compounded is determined by the amount of the thermoplastic polyester elastomer (A) and the amount of the chlorinated polyethylene (B).
Is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight in total. If the amount is less than 0.01 part by weight, the crosslinking reaction does not proceed sufficiently, and there is a possibility that sufficient heat resistance cannot be obtained. More preferably 0.05 part by weight or more, even more preferably 0.2 part by weight.
It is more than weight part. On the other hand, if it exceeds 10 parts by weight, the crosslinking reaction proceeds excessively, the hardness becomes too high, and the rubber elasticity may be lost. More preferably, it is at most 5 parts by weight, even more preferably at most 2 parts by weight.

The thermoplastic elastomer composition of the present invention comprises:
Those obtained by blending a compatibilizer (D) in addition to the thermoplastic polyester elastomer (A), the chlorinated polyethylene (B) and the crosslinking agent (C) are preferable. By blending the compatibilizer (D), the interfacial tension between the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) is reduced, and the adhesive strength at the interface is improved, so that the resulting heat The mechanical properties of the plastic elastomer composition are improved.

As the compatibilizer (D), a copolymer having a portion having an affinity for the thermoplastic polyester elastomer (A) and a portion having an affinity for the chlorinated polyethylene (B), for example, a block copolymer, A graft copolymer or the like can be used. Further, a polymer having a functional group capable of chemically reacting with the thermoplastic polyester elastomer (A) or the chlorinated polyethylene (B) can also be used. The compatibilizer (D) used in the present invention includes:
Polymers having such functional groups are preferred. Examples of the functional group include an epoxy group, a carboxyl group, a carbonyl group, a halogen atom, an amino group, an oxazoline group, and a hydroxyl group. Among them, an epoxy group or a carboxyl group is preferred, and an epoxy group is most preferred, in view of good reactivity with a functional group of the thermoplastic polyester elastomer (A). The polymer having an epoxy group may be obtained by copolymerizing a monomer having an epoxy group such as glycidyl methacrylate with another monomer, or may be obtained by epoxidizing a double bond after polymerization. But it is good. Examples of those having a carboxyl group include a polymer graft-modified with maleic anhydride.

The amount of the compatibilizer (D) is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the total of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B). When the amount is less than 0.1 part by weight, the obtained thermoplastic elastomer composition often has insufficient mechanical strength. More preferably 0.2 parts by weight or more,
More preferably, it is 0.5 part by weight or more. On the other hand, when it exceeds 20 parts by weight, oil resistance often deteriorates. It is more preferably at most 10 parts by weight, and even more preferably at most 5 parts by weight.

As described above, the polymer having an epoxy group is the most suitable as the compatibilizer (D) of the present invention. At this time, the weight of the oxygen element derived from the epoxy group contained in the compatibilizer (D) is determined. Ratio to the weight of the thermoplastic polyester elastomer (A) [(weight of oxygen element derived from epoxy group) /
(Weight of A)] is particularly preferably 1/10000 to 5/1000. If this ratio is less than 1/10000, the mechanical strength of the thermoplastic elastomer composition obtained may be insufficient. More preferably 2/10
000 or more. On the other hand, when the ratio exceeds 5/1000, excessive crosslinking reaction proceeds due to heat during kneading, and rubber elasticity may be lost. More preferably 2/1
000 or less, more preferably 1/1000 or less. Here, the weight of the oxygen element derived from the epoxy group contained in the compatibilizer (D) is a value obtained by multiplying the number of moles of the epoxy group in the compatibilizer (D) by 16 of the atomic weight of oxygen.

The thermoplastic elastomer composition of the present invention comprises a basic substance (E) in addition to the thermoplastic polyester elastomer (A), the chlorinated polyethylene (B) and the crosslinking agent (C). Those are preferred. By blending a basic substance, hydrogen chloride generated at the time of the crosslinking reaction can be captured, and the crosslinking reaction can proceed smoothly. The basic substance (E) is not particularly limited as long as it reacts with hydrogen chloride to form a salt, and either an inorganic base or an organic base can be used. For example, Periodic Table 2
An oxide or salt of a metal belonging to the genus (hydroxide, carboxylate, silicate, carbonate, phosphite, borate, or the like), lead oxide, hydrotalcite, or the like can be used. Among these, metal oxides of the second group of the periodic table such as magnesium oxide and hydrotalcite are preferred, and hydrotalcite is most preferred.

Hydrotalcite is a double salt comprising a hydroxide and a carbonate of magnesium and aluminum, and may have water of crystallization. For example, Mg _4.5 Al
_{2 (OH) 13 CO 3 ·} 3.5H 2 O and _Mg 4 Al
₂ (OH) ₁₂ CO ₃ .3H ₂ O or a structure obtained by removing water of crystallization therefrom is exemplified as a typical example.
Since it is easy to suppress foaming during melt-kneading, those having no crystallization water are often preferable. Hydrotalcite is usually a powder composed of fine particles, and can be easily dispersed in a resin. Hydrotalcite is preferred because it helps the cross-linking reaction to proceed at an appropriate rate, and chloride, which is a reaction product when hydrogen chloride is captured, hardly causes a side reaction.

The preferred amount of the basic substance (E) is 5 to 100 parts by weight based on 100 parts by weight of the chlorinated polyethylene (B).
Parts by weight. If the amount is less than 5 parts by weight, hydrogen chloride generated during the crosslinking reaction cannot be sufficiently captured, and the mechanical strength of the obtained thermoplastic elastomer composition tends to decrease. It is more preferably at least 10 parts by weight, and even more preferably at least 20 parts by weight. On the other hand, if it exceeds 100 parts by weight, the crosslinking reaction may proceed excessively and rubber elasticity may be lost. It is more preferably at most 70 parts by weight, more preferably at most 50 parts by weight.

The thermoplastic elastomer composition of the present invention comprises:
Further, when an anti-aging agent is added, the heat aging resistance can be improved, which is preferable. The type of antioxidant to be added is not particularly limited, and examples thereof include a phenolic antioxidant, an amine antioxidant, an imidazole antioxidant, a dithiocarbamate antioxidant, and a phosphate antioxidant. Among them, phenolic antioxidants, particularly hindered phenolic antioxidants, are preferred. The preferred amount of the antioxidant is 0.01 to 10 parts by weight based on 100 parts by weight of the total of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B).
When the amount is less than 0.01 part by weight, the effect of improving the heat aging resistance is often insufficient. It is more preferably at least 0.05 part by weight, even more preferably at least 0.1 part by weight. On the other hand, if it exceeds 10 parts by weight, a further improvement in heat aging resistance cannot be expected in many cases. More preferably, it is at most 5 parts by weight, even more preferably at most 2 parts by weight.

The thermoplastic elastomer composition of the present invention contains a filler and a filler within a range not impairing fluidity and mechanical strength.
For example, calcium carbonate, calcium silicate, clay, kaolin, talc, silica, diatomaceous earth, mica powder, asbestos, alumina, barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, carbon black , Carbon fiber and the like. Further, a coloring agent such as carbon black, ultramarine blue, titanium oxide, zinc white, red iron blue, navy blue, azo pigment, nitrone pigment, lake pigment, phthalocyanine pigment and the like can be blended. Furthermore, various reinforcing agents, plasticizers, antioxidants, light stabilizers, flame retardants, lubricants, foaming agents, mold release agents, antistatic agents or other resin components are compounded within a range not to impair the effects of the present invention. You may.

The thermoplastic elastomer composition of the present invention comprises:
The thermoplastic polyester elastomer (A), the chlorinated polyethylene (B), and the crosslinking agent (C) are obtained by melt-kneading and dynamically crosslinking. By dynamically advancing the crosslinking reaction, the chlorinated polyethylene (B) component has a crosslinked structure, and the compression set of the obtained thermoplastic elastomer composition is greatly improved. At the same time, the heat aging resistance is also improved, and as a result, a thermoplastic elastomer composition useful for use at a high temperature for a long time is obtained.

Thermoplastic polyester elastomer (A)
The apparatus for melt-kneading the chlorinated polyethylene (B) and the crosslinking agent (C) is not particularly limited, and an extruder, a kneader, a Banbury mixer, an open roll and the like can be used. Particularly, a twin-screw extruder is preferable because it can be sufficiently kneaded. At this time, it is preferable that the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) are previously melt-kneaded, and then the crosslinking agent (C) is blended and further melt-kneaded. This is because the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) are preliminarily melt-kneaded and sufficiently dispersed to allow the crosslinking reaction to proceed, whereby the dispersion and crosslinking can be efficiently performed. For example, using a plurality of extruders, the melt-kneaded product of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) is once discharged from one extruder, and is then discharged to another extruder together with the crosslinking agent (C). It may be charged and melt-kneaded. Also, using one extruder,
After the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) are melt-mixed, the crosslinking agent (C) may be charged in the middle of the extruder.

When the thermoplastic elastomer composition of the present invention contains a basic substance (E), the chlorinated polyethylene (B) and the basic substance (E) are previously dry-blended or melted. It is preferable that the blended product is supplied to an extruder, melt-kneaded with the thermoplastic polyester elastomer (A), and then the crosslinking agent (C) is blended and further melt-kneaded. The basic substance (E) can be efficiently dispersed in the chlorinated polyethylene (B) that generates hydrogen chloride at the time of the crosslinking reaction. As a result, the crosslinking reaction can proceed efficiently, and Is efficiently captured.

The method of previously mixing the chlorinated polyethylene (B) and the basic substance (E) may be dry blending or melt blending. For example, when the basic substance (E) is a powder or a liquid, the surface of the chlorinated polyethylene (B) is dry-blended together with the chlorinated polyethylene (B) in the form of powder, granules or pellets. A basic substance (E) can be attached. By supplying this to the extruder, the basic substance (E) can be efficiently dispersed in the chlorinated polyethylene (B) at the time of subsequent melt-kneading. When the chlorinated polyethylene (B) and the basic substance (E) are previously melt-mixed, the basic substance (E) can be efficiently dispersed in the chlorinated polyethylene (B). Better than dry blending, but with a slightly more complicated manufacturing process.

The method of blending the other components is not particularly limited, but it is preferable that the other components are blended and melt-kneaded before adding the crosslinking agent (C). That is, when a blend of a chlorinated polyethylene (B) and a basic substance (E) and a thermoplastic polyester elastomer (A) are charged into an extruder, a compatibilizer (D), a crosslinking assistant, and an antioxidant are used. It is preferable to add various additives such as. After dispersing or dissolving these components satisfactorily, a crosslinking agent (C) is added and melt-kneaded while a crosslinking reaction proceeds, whereby a thermoplastic elastomer composition in which each component is homogeneously mixed is obtained. It is.

When melt-kneading the thermoplastic polyester elastomer (A), the chlorinated polyethylene (B) and the cross-linking agent (C), it is preferable to use a twin-screw extruder. It is preferable that the average temperature of the cylinder of the machine is 150 to 200 ° C. here,
The average temperature of the cylinder of the twin-screw extruder refers to a weighted average value obtained by measuring the temperatures of a plurality of blocks constituting the cylinder of the twin-screw extruder and considering the length of each block. If the value is less than 150 ° C., the thermoplastic polyester elastomer (A) may not be sufficiently melted. The temperature is more preferably 160 ° C or higher, and still more preferably 170 ° C or higher. On the other hand, when the temperature exceeds 200 ° C., the temperature of the resin composition during melt-kneading becomes too high, and the chlorinated polyethylene (B) may deteriorate. More preferably 19
The temperature is 5 ° C or lower, more preferably 190 ° C or lower.

It is preferable that the linear velocity around the screw of the twin screw extruder is 5 to 25 m / min. Here, the linear velocity of the outer periphery of the screw is a numerical value obtained by multiplying the diameter of the screw by the pi and the number of revolutions, and when the distance between the outer periphery of the screw and the inner wall surface of the cylinder is constant, regardless of the screw diameter. It is a numerical value proportional to the shear rate applied to the resin. If this value is less than 5 m / min, kneading may not be performed sufficiently and the crosslinking reaction may not proceed uniformly.
It is more preferably at least 7 m / min, even more preferably 9 m / min.
/ Min or more. On the other hand, if it exceeds 25 m / min, the dispersion state of the obtained thermoplastic elastomer composition may be poor and the mechanical strength may be deteriorated. It is more preferably at most 20 m / min, even more preferably at most 15 m / min. When kneading different kinds of resins, it is generally preferable that the shear rate at the time of kneading can be finely dispersed as the shear rate increases, but when the thermoplastic elastomer composition of the present invention is produced, the shear rate is large. If it is too high, the performance may deteriorate, which is surprising. This point, including details of the dispersion state, will be described later.

The temperature of the molten resin discharged from the twin-screw extruder is preferably from 180 to 230 ° C. The temperature of the discharged resin is a value determined by the relationship between the set temperature of the cylinder and the shear heat of the molten resin in the cylinder, and the numerical value increases as the set temperature of the cylinder increases and the shear rate applied to the molten resin increases It is. This value is 180 ° C
If less than the thermoplastic polyester elastomer (A)
May not be sufficiently melted. More preferably 190
C. or higher, more preferably 200 ° C. or higher. On the other hand, when the temperature exceeds 230 ° C., the temperature of the resin composition during melt-kneading becomes too high, and the chlorinated polyethylene (B) may deteriorate. The temperature is more preferably 225 ° C or lower, and still more preferably 220 ° C or lower.

The average temperature of the cylinder of the twin screw extruder,
Both the linear velocity of the screw outer periphery and the temperature of the molten resin to be discharged are conditions under which all components of the thermoplastic polyester elastomer (A), chlorinated polyethylene (B) and crosslinking agent (C) are melt-kneaded. Yes, the melt-kneading conditions before blending the crosslinking agent (C) can be set separately.

The configuration of the twin-screw extruder used for melt-kneading the thermoplastic polyester elastomer (A), the chlorinated polyethylene (B) and the crosslinking agent (C) is not particularly limited. L / D is 20
It is preferable that it is above. Here, L / D indicates the ratio of the screw length (L) to the screw diameter (D). If the L / D is less than 20, the residence time of the molten resin becomes short, and the time for advancing the crosslinking reaction becomes insufficient, and the mechanical strength, compression set and heat aging of the obtained thermoplastic elastomer composition are reduced. There is a possibility that the properties may be insufficient. More preferably, L / D is 25 or more, and still more preferably, 30 or more. Usually, L / D is 100 or less.

It is also preferable that the ratio of the length of the kneading portion to the entire length of the screw is 2/100 to 30/100. Here, the kneading portion is a portion mainly intended to knead the molten resin, and is a portion other than a portion intended only to extrude the resin forward. Examples of the screw portion forming the kneading portion include a kneading disk mounting portion and a reverse flight screw portion. Examples of the screw portion merely constituting the portion for extruding the resin forward include a full flight screw portion and the like.

If the ratio of the length of the kneading portion to the entire length of the screw is less than 2/100, the kneading effect becomes insufficient and the crosslinking reaction may not proceed sufficiently. It is more preferably at least 5/100, and even more preferably at least 10/100. On the other hand, the ratio is 30/1
If it exceeds 00, the dispersion state of the obtained thermoplastic elastomer composition becomes poor, and the mechanical strength may deteriorate. It is more preferably at most 25/100, even more preferably at most 20/100.

As described above, when kneading different kinds of resins, it is generally preferable to set the kneaded portion of the screw to a certain ratio or more because it is possible to finely disperse the resin. In many cases, the thermoplastic elastomer composition of the present invention is used. In the production of, if the shear rate is too high, the performance may be adversely deteriorated, which is a surprising point. As described above, while it is necessary to increase L / D by a certain value or more in order to secure a reaction time for allowing a crosslinking reaction to proceed, that is, a residence time, in order to prevent excessive kneading, such a method is required. It is effective to reduce the proportion of the kneaded portion.

The results of observing the dispersion state of the thermoplastic elastomer composition thus obtained by an electron microscope are shown in FIGS. 1 and 2. FIG. 1 shows a case where a screw having a kneading portion ratio of 15/100 was used, and the linear velocity around the screw was set at 12.
The molded product made of the thermoplastic elastomer composition obtained at the time of kneading at 3 m / min was broken by cooling with liquid nitrogen, and the fracture surface was observed. Magnesium oxide particles are observed, but no clear interface is observed in the resin part, and it is presumed that there is no clear interface, or that even if present, the bonding strength of the interface is sufficiently strong.

On the other hand, FIG. 2 shows that the ratio of the kneading portion is 36/10
This is a result of observing a fracture surface when kneading using a screw of 0 and kneading at a linear velocity of 28.3 m / min on the outer periphery of the screw. It is observed that there are largely two phases, one of which has a particle size of 0.1-0.2 μm.
Many fine particles having a size of about m are present. Although it is not always clear about the resin component forming each phase or the fine particles, the fine particles are reacted with the thermoplastic polyester elastomer (A) at the time of melt-kneading to react with the thermoplastic polyester elastomer (A). It is presumed that the quantitative or compositional balance between the hard segment and the soft segment in the medium is lost, and the microphase-separated structure is destroyed, so that relatively large particles are observed.

Therefore, in order to suppress such undesired progress of the reaction, the temperature during melt-kneading should not be too high, and the shear rate during kneading should not be too high, as described above. Is considered to be effective. That is, the dispersed state of each component in the thermoplastic elastomer composition of the present invention is such that when the molded article is fractured in liquid nitrogen and the fracture surface is observed, no clear interface between the resin components is observed. This is preferable because sufficient mechanical strength can be obtained.

The method for molding a molded article using the thermoplastic elastomer composition of the present invention is not particularly limited, and various melt molding methods similar to those for molding ordinary thermoplastic resins can be employed. It can be used for various molding methods such as injection molding, extrusion molding, and blow molding.

In the molded product obtained by melt-molding the thermoplastic elastomer composition of the present invention, the tensile strength in the heat aging test in air at 150 ° C. is 20 to 3 after the start of the test.
It is preferred that it shows a local minimum during 00 hours and then rises and, after 500 hours, retains at least 50% of the tensile strength before the test. It is more preferable to maintain a value of 60% or more, and it is still more preferable to maintain a value of 70% or more. It is not clear why the tensile strength during the heat aging test shows such a peculiar change with time, but by showing such a change with time, it seems that heat aging resistance for a long time is expressed. . As shown in FIG. 3 in the examples described later, the same applies to a molded article made of only a thermoplastic polyester elastomer (Comparative Example 3) and a molded article made of chloroprene rubber that is a crosslinked rubber (Comparative Example 4). Of the molded article made of the thermoplastic elastomer composition of the present invention (Example 1) is significantly reduced in a shorter time.

Further, in the molded article obtained by melt-molding the thermoplastic elastomer composition of the present invention, the elongation in the heat aging test in air at 150 ° C. is 500% after the start of the test.
It is also preferred to have a value of 10% or more even after time. As shown in FIG. 4 in the examples described later, a molded article made of only the thermoplastic polyester elastomer (Comparative Example 3) and a molded article made of chloroprene rubber (Comparative Example 4)
In the case of the above, the elongation in the same heat aging test shows substantially zero after 500 hours and loses the flexibility, whereas the molding made of the thermoplastic elastomer composition of the present invention. The article (Example 1) still has an elongation of 50% and is flexible. More preferably, it has an elongation of 20% or more.

Further, as shown in FIG. 5, the molded article made of the thermoplastic elastomer composition of the present invention (Example 1) has a chloroprene rubber whose hardness does not substantially change in a heat aging test and whose hardness changes greatly. As compared with the molded product (Comparative Example 4) composed of One of the features of the present invention is that the heat aging resistance is greatly improved as compared with the materials widely used in the past.

Although the use of the thermoplastic elastomer composition of the present invention is not particularly limited, it is excellent in mechanical strength, flexibility, low compression set, oil resistance, heat resistance and heat aging resistance. It is suitably used for applications that make use of it. For example, it can be used for automobile parts, architectural parts, electric parts, mechanical parts, etc., but is particularly preferably used for automobile parts. In recent years, from the viewpoint of environmental protection, the demand for improving the fuel efficiency of automobiles has become even more severe.However, the thermoplastic elastomer composition of the present invention, which has higher hardness and mechanical strength than conventional crosslinked rubbers, is more important in that respect. It is preferable that a thin molded product can be used. Also, since it has excellent oil resistance, it is suitable as an automobile part which often comes into contact with various greases and oils. Furthermore, since the long-term durability, particularly the durability at high temperatures, is often required for automobile parts, the thermoplastic elastomer composition of the present invention having a small compression set and excellent heat aging resistance is useful.

As specific automobile parts, for example, it is suitably used as a boot material for covering various joints or a hose material for engine intake. As the engine intake hose, it is preferable to use a hose that is frequently exposed to high temperatures and that connects between an air cleaner and an engine, and it is particularly preferable to use a hose for a turbo engine.

The most useful application of the thermoplastic elastomer composition of the present invention is as a joint boot. Since the joint boot is filled with grease, it is required to have oil resistance, and it is preferable that the joint boot is obtained by melt-molding the thermoplastic elastomer composition of the present invention. The joint covered by the joint boot of the present invention is not particularly limited, and can be used for covering various joints for automobiles, machines, and the like. Among them, it is suitably used as a constant velocity joint boot for automobiles. The constant velocity joint boot is required to have durability against grease filled therein and durability against vibration and bending, and the thermoplastic elastomer composition of the present invention is suitably used.

The joint boot of the present invention is molded using the above-mentioned thermoplastic elastomer composition. Extrusion molding, injection molding, blow molding and the like can be employed as the molding method, but injection molding is preferred from the viewpoint of easy control of wall thickness and molding efficiency. In the case of the constant velocity joint boot for automobiles (1), the shape is a flat cylindrical shape so that both ends can be attached to other members as shown in the cross-sectional view of FIG. 6, and the center is filled with grease. Hollow part (2)
Having a bellows shape whose side surface is composed of two or more peaks (3)
It is formed in. One end (4) of the boot is a relatively small opening because it is attached to a small diameter axle, and the other end (5) of the boot is a relatively large opening because it is attached to the outer ring of a constant velocity joint.

The joint boot of the present invention preferably has an average thickness of 0.5 to 3 mm. For example,
When chloroprene rubber, which is a crosslinked rubber, is used as a constant velocity joint boot for automobiles, the average thickness is usually about 4 to 5 mm. The thickness can be reduced to about 5 to 3 mm, which can contribute to weight reduction of an automobile. When the thickness is less than 0.5 mm, the strength is often insufficient, more preferably 0.8 mm or more, and still more preferably 1 mm or more. On the other hand, when the thickness exceeds 3 mm, the flexibility as a boot often becomes insufficient and the weight also increases. It is more preferably at most 2.5 mm, even more preferably at most 2 mm.

In general, two constant velocity joint boots for a vehicle are mounted on the outside (wheel side) and inside (body center side) of four wheels. Among them, it is particularly preferable to use it for a constant velocity joint boot on the engine side. Here, the constant velocity joint boot on the engine side is a joint boot that covers a constant velocity joint on the inner side (the center side of the vehicle body) on the side (often the front wheel side) on which the engine is mounted. For example, in a vehicle having an engine mounted on the front part of the vehicle, it is preferable to use the joint boot for covering a constant velocity joint inside the front wheel. The constant velocity joint boot on the engine side often becomes high temperature because heat from the engine is transmitted, and uses the thermoplastic elastomer composition of the present invention, which has a small compression set at high temperature and excellent heat aging resistance. Is particularly effective.

The constant velocity joint boot of the present invention is attached by covering the axle and the outer ring of the joint with the cylindrical portions at both ends of the boot and tightening the band from above. The rotational force from the drive shaft is transmitted to a wheel-side shaft via a constant velocity joint. At this time, since the angle of the shaft on the wheel side changes relative to the drive shaft, the boot needs to be deformed in accordance with the change in the angle and the change in the angular velocity, and the bellows of the boot expands and contracts. .

The joint boot formed by molding the thermoplastic elastomer composition of the present invention has a lower hardness and a smaller compression set than the joint boot formed by molding the thermoplastic polyester elastomer alone. Fixing is possible even with a small tightening force. Conventionally, when using a joint boot made of a thermoplastic polyester elastomer alone, a fastening bracket consisting of a metal band having a thickness of about 1 mm and a width of about 10 mm is usually used on the axle of the automobile and the outer ring of the joint. Although it was fixed, in the case of a joint boot formed by molding the thermoplastic elastomer composition of the present invention, fixing can be performed using a thin band, and the thickness is 0.2 to
It can be fixed using a metal band having a width of 0.8 mm and a width of 2 to 12 mm.

That is, an automobile drive structure which is fixed to the outer ring of an axle and a joint using a metal band having a thickness of 0.2 to 0.8 mm and a width of 2 to 12 mm is a preferred embodiment of the present invention. It is an embodiment. By employing such a unit, it is possible to contribute to reducing the weight of an automobile. If the thickness of the metal band is less than 0.2 mm, the tightening force tends to be insufficient. More preferably, it is 0.3 mm or more. On the other hand, when the thickness exceeds 0.8 mm, the weight of the metal band increases, which may not be preferable from the viewpoint of reducing the weight of the automobile. More preferably, it is 0.6 mm or less. The material of the metal band is not particularly limited, but stainless steel and brass are exemplified. The structure of the metal band is not particularly limited as long as it can be tightened, and examples thereof include a structure tightened by caulking, a structure tightened with screws, a structure having a hook and an opening for hanging it, a structure bending a metal plate and bending, and the like. .

[0073]

The present invention will be described in more detail with reference to the following examples. Various tests in the examples were performed according to the following methods.

(1) DSC measurement Differential scanning calorimeter DSC12 manufactured by Seiko Denshi Kogyo KK
The measurement was performed at a heating rate of 10 ° C./min using 0 U. The heat of crystal fusion and the melting point were obtained from the obtained chart.

(2) Tensile strength and elongation A 2 mm thick sheet was punched out with a No. 3 dumbbell mold to prepare a test piece, and the tensile strength and elongation were measured according to JIS K6301. The sample before the test piece was put into the heat aging test and the sample after the heat aging test was given for a predetermined time were used for measurement.

(3) Hardness JIS A hardness was measured according to JIS K6301. At this time, seven sheets having a thickness of 2 mm used in the above-mentioned "(2) Tensile strength and elongation" were stacked and subjected to measurement.

(4) Compression Set The compression set was measured according to JIS K6262. The dimensions of the test piece were a disk having a diameter of 29 mm and a thickness of 12.5 mm. 13% compressed in the thickness direction at a rate of 25%
After holding at 0 ° C. for 96 hours, the compression set was measured.

Example 1 "Eraslen 301A" manufactured by Showa Denko KK was used as the chlorinated polyethylene (B). This chlorinated polyethylene has a chlorine content of 32% by weight and a heat of crystal fusion of 2J.
/ G, melt flow rate [180 ° C., 21.6 k
gf (212 N) load] was 1.6 g / 10 min.
Hydrotalcite "DHT-4C" manufactured by Kyowa Chemical Industry Co., Ltd. was used as the basic substance (E). This hydrotalcite is Mg _4.5 Al ₂ (OH) ₁₃ CO
_This is a white powder having a composition of ₃ . 20 parts by weight of the chlorinated polyethylene (B) granules and 6 parts by weight of the hydrotalcite were dry-blended to uniformly adhere hydrotalcite powder to the surfaces of the chlorinated polyethylene granules.

Subsequently, "Perprene P-4" manufactured by Toyobo Co., Ltd. was used as the thermoplastic polyester elastomer (A).
80 parts by weight of “4DT”, and 0.8% of dicyclohexylamine salt of 2-mercaptobenzothiazole as a crosslinking aid.
Parts by weight, 2 parts by weight of "Epoblend A1010" manufactured by Daicel Chemical Industries, Ltd. as a compatibilizer (D), and "Adecastab AO-60" manufactured by Asahi Denka Kogyo Co., Ltd. of a hindered phenol-based antioxidant as an antioxidant. 0.4 parts by weight and 0.3 parts by weight of "ADK STAB AO-412S" manufactured by the same company were mixed with the chlorinated polyethylene (B) and the basic substance (E).
Was further blended with the dry blended product of the above and was simultaneously charged into a twin-screw extruder.

The “perprene P-44DT” of the thermoplastic polyester elastomer (A) used here is a block copolymer having polybutylene terephthalate as a hard segment and polytetramethylene glycol as a soft segment. As a result of DSC measurement, the melting point of the hard segment was 194 ° C. Although the melting point of the soft segment was not clearly observed, an inflection point presumed to be derived from the glass transition point was observed at around -70 ° C.

The “Epoblend A1010” of the compatibilizer (D) used was obtained by mixing 60% by weight of a block obtained by polymerizing styrene and a block 40 obtained by polymerizing butadiene.
It is obtained by epoxidizing a part of a double bond derived from butadiene in a block copolymer composed of% by weight. The content of the oxygen element derived from the epoxy group in “Epoblend A1010” is 1.6% by weight.

The twin-screw extruder used was a coaxial twin-screw extruder “TEX30α” manufactured by Nippon Steel Works, Ltd. The screw diameter is 30 mm and L / D is 42. A kneading portion composed of a kneading disc and a reverse flight screw is disposed in two places in the screw, and the ratio of the total length to the total length of the screw is 15 /.
100. The cylinder is composed of 12 blocks, and the set temperature of each block is from 180 ° C. (2.75) to 180 ° C. (4.5) from the entrance side to the exit side.
→ 190 ° C (3.5) → 200 ° C (3.0) → 190 ° C
(3.0) → 180 ° C (4.5) → 180 ° C (3.5)
→ 180 ° C (3.5) → 180 ° C (3.0) → 180 ° C
(3.75) → 180 ° C. (3.5) → 180 ° C. (3.
5) The temperature is set to 210 ° C. (die head). Numerical values in parentheses are L / D values of each block.
The average temperature of the cylinder based on the weighted average considering L / D is 183.0 ° C. The screw rotation speed of the extruder was 130 rpm. The linear velocity around the screw is 12.
It was 3 m / min.

The dry-blended mixture was introduced into the twin-screw extruder at a rate of 6.5 kg / hour. The strands taken out of the die were cooled and solidified in a water bath, cut with a pelletizer, and dried in an oven at 80 ° C. for 5 hours to obtain pellets before crosslinking.

With respect to 107.7 parts by weight of the pellet before crosslinking (80 parts by weight of the thermoplastic polyester elastomer (A) and 20 parts by weight of the chlorinated polyethylene), 2,4,6-triol was used as the crosslinking agent (C). Mercapto-1,3,5
Dry blending 0.2 parts by weight of triazine,
It was again charged into the twin screw extruder. The model of the twin-screw extruder, the screw configuration, the operating conditions, and the raw material input amount were set to exactly the same conditions as when producing the above-mentioned pellets before crosslinking. The temperature of the molten resin discharged from the die was 206 ° C. The strands taken out of the die were cooled and solidified in a water bath, cut with a pelletizer, and dried in an oven at 80 ° C. for 5 hours to obtain pellets comprising the thermoplastic elastomer composition of the present invention.

Using the obtained pellets of the thermoplastic elastomer composition as raw materials, a vertical injection molding machine of 40 ton pressure was used at a molding temperature of 220 ° C. and 120 mm × 120 mm.
The sheet was formed into a sheet of × 2 mm, and this sheet was punched out using a No. 3 dumbbell mold to prepare a dumbbell-shaped test piece. When the tensile strength and the elongation were measured using this dumbbell type test piece, the tensile strength was 200 kgf / cm ² (19.6MP
a), the elongation was 780%;

JIS measured by stacking seven sheets
The A hardness was 89. The mold was replaced with the same injection molding machine used to mold the sheet, and a disk-shaped test piece for measuring compression set having a diameter of 29 mm and a thickness of 12.5 mm was heated at 130 ° C. for 96 hours. The subsequent compression set measured was 43%. These results are summarized in Table 1.

A 3 mm wide strip-shaped test piece was cut out from the sheet, a notch was formed in the side surface, and the cut piece was immersed in liquid nitrogen and cooled, and the cut portion was broken. Magnification 1000 using an electron microscope
Observed at 0x. The photograph is shown in FIG.

Further, a plurality of dumbbell-shaped test pieces were left in a gear type aging tester set at 150 ° C. in an air atmosphere to perform a heat aging test. The test piece was taken out at predetermined time intervals, allowed to cool sufficiently, and then measured for tensile strength, elongation and hardness. The results are shown in Tables 2 to 4 and FIGS.
Shown in

Using the pellets obtained from the obtained thermoplastic elastomer composition as raw materials, a constant velocity joint boot for automobiles was produced at a molding temperature of 220 ° C. using a horizontal injection molding machine at a pressure of 200 tons.

FIG. 6 is a sectional view of the obtained constant velocity joint boot for an automobile (1). A hollow portion (2) filled with grease is provided at a central portion, and the side surface thereof is formed in a bellows shape (3) including a plurality of peaks. One end (4) of the boot is a small opening having a diameter of about 25 mm since it is attached to the axle, and the other end (5) of the boot is a large opening having a diameter of about 80 mm because it is attached to the outer ring of the constant velocity joint. The average thickness of the bellows portion is 1.2 mm, and the thickness of the cylindrical portion (6, 6 ') beside the opening is slightly larger than that. On the outer surface of the cylindrical portion (6, 6 '), a band mounting groove (7, 7') having a depth of about 2 mm and a width of about 8 mm is formed. Can be fixed.

The obtained constant velocity joint boot was filled with grease and assembled to the axle and the outer ring of the constant velocity joint. After assembling, the both ends of the boot are bent by bending a metal plate, 0.4mm thick, 7m wide
m and fastened using a metal band. FIG. 7 shows a metal band (8) used for fixing to the outer ring of the joint. The inner surfaces of the annular band (9) are welded together at a welding point (10) and the welding point (10)
, A fastening metal plate (11) having a thickness of about 1 mm is further welded. The outer ring of the joint with the boot is inserted into the ring-shaped band (9), and then the metal plate (11) for tightening is tilted in the direction of the arrow to tighten the fixed blade (12) welded to the ring-shaped band inside. And the metal plate (11) for fastening is fixed.

After fixing the constant velocity joint boot to the axle and the outer ring of the joint as described above, an operation test was performed. At room temperature, the intersection angle between the inner and outer axles at the joint portion was maintained at 40 degrees, and an operation test was performed for one hour at a rotation speed of 600 rpm. As a result, no particular problem occurred, and it was confirmed that the structure was sufficiently fixed.

Example 2 In the same manner as in Example 1, pellets before crosslinking were obtained. The obtained pre-crosslinking pellets were dry-blended with the same crosslinking agent (C) as in Example 1 at the same ratio, and then charged into a twin-screw extruder. The twin screw extruder used was the same as “TEX
30α ”.

The screw diameter was 30 mm and the L / D was 42
However, the screw configuration is different from that used in Example 1 as follows. That is, a kneading portion composed of a kneading disc and a reverse flight screw is arranged in six places in the screw, and the ratio of the total length to the entire length of the screw is 36/100. The cylinder is composed of 12 blocks, and the set temperature of each block is from the entrance side to the exit side,
180 ° C (2.75) → 180 ° C (4.5) → 190 ° C
(3.5) → 200 ° C (3.5) → 190 ° C (3.5)
→ 180 ℃ (4.5) → 180 ℃ (3.0) → 180 ℃
(3.5) → 180 ° C (3.0) → 180 ° C (4.0)
→ 180 ° C (3.0) → 180 ° C (3.25) → 220
° C (die head). Numerical values in parentheses are L / D values of each block. The average temperature of the cylinder based on the weighted average taking L / D into consideration is 183.3 ° C. The screw rotation speed of the extruder was 300 rpm. The linear velocity around the screw was 28.3 m / min.

The dry-blended mixture was introduced into the twin-screw extruder under the above operating conditions at a rate of 6 kg / hour. The temperature of the molten resin discharged from the die was 221 ° C. The strands drawn from the die are cooled and solidified in a water bath, cut with a pelletizer, and dried in an oven at 80 ° C. for 5 minutes.
After drying for a period of time, pellets comprising the thermoplastic elastomer composition of the present invention were obtained.

Using the obtained thermoplastic elastomer composition, various test pieces were molded and evaluated in the same manner as in Example 1. The JIS A hardness was 91 and the tensile strength was 108 kg.
f / cm ² (10.6 MPa), elongation 350%, 13
The compression set after heating at 0 ° C. for 96 hours was 48%.
These results are summarized in Table 1. Further, the fracture surface was observed with a scanning electron microscope in the same manner as in Example 1. The photograph is shown in FIG.

Comparative Example 1 A thermoplastic elastomer composition was obtained in the same manner as in Example 1 except that "Eraslen 303B" manufactured by Showa Denko KK was used as the chlorinated polyethylene (B). The chlorine content of this chlorinated polyethylene was 32% by weight, the heat of crystal fusion was 50 J / g, and the melt flow rate [180 ° C., 2
1.6 kgf (212 N) load] is 25 g / 10 min.

Using the obtained thermoplastic elastomer composition, various test pieces were molded and evaluated in the same manner as in Example 1. The JIS A hardness was 90 and the tensile strength was 170 kg.
f / cm ² (16.7 MPa), elongation 800%, 13
The compression set after heating at 0 ° C. for 96 hours was 58%.
These results are summarized in Table 1.

Comparative Example 2 Various test pieces were molded and evaluated in the same manner as in Example 1 using the pre-crosslinked pellets obtained in the intermediate stage of producing the thermoplastic elastomer composition in Example 1, and evaluated.
The hardness is 88 and the tensile strength is 160 kgf / cm ² (15.
7 MPa), the elongation was 800%, and the compression set after heating at 130 ° C. for 96 hours was 63%. Table 1 shows these results.
Are shown together.

Comparative Example 3 In the same manner as in Example 1, except that the thermoplastic polyester elastomer (A) “Perprene P-44DT” used in Example 1 was used instead of the thermoplastic elastomer composition obtained in Example 1. When various test pieces were molded and evaluated,
JIS A hardness is 93, tensile strength is 300kgf / cm
² (29.4 MPa), elongation 890%, 130 ° C., 9
The compression set after heating for 6 hours was 47%. These results are summarized in Table 1. A heat aging test was performed in the same manner as in Example 1. The results are shown in Tables 2 to 4 and FIGS.
Shown in

In place of the thermoplastic elastomer composition obtained in Example 1, the thermoplastic polyester elastomer (A) “Perprene P-44D” used in Example 1 was used.
A constant velocity joint boot for an automobile was formed in the same manner as in Example 1 using only "T", and an operation test was performed. As a result, a gap occurred between the outer race of the constant velocity joint and the boot, and grease leakage from that portion was observed.

Comparative Example 4 100 parts by weight of chloroprene rubber, carbon black 50
Parts by weight, zinc white (zinc oxide) 5 parts by weight, stearic acid 1
Parts by weight, magnesium oxide 5 parts by weight, di-2-ethylhexyl sebacate (DOS) 20 parts by weight, an antioxidant “NOCRACK 810-NA (N-
2 parts by weight of "isopropyl-N'-phenyl-p-phenylenediamine)" were charged into a Banbury mixer and kneaded. The kneaded product is put on a roll together with 1 part by weight of a crosslinking accelerator "NOCSELER DM (di-2-benzothiazolyl disulfide)" manufactured by Ouchi Shinko Chemical Co., Ltd., kneaded between the rolls, and then formed into a sheet. I put it out.

The obtained sheet is 120 mm × 300 mm
× 2mm die, 160
The mixture was heated at 20 ° C. for 20 minutes for vulcanization. When the obtained test piece was evaluated in the same manner as in Example 1, the JIS A hardness was 57, the tensile strength was 180 kgf / cm ² (17.6 MPa), and the elongation was 490%. The mold was replaced under the same conditions as those for forming the sheet, and the diameter was 29 mm and the thickness was 12.
A 5 mm disk-shaped test piece for measuring compression set was molded,
When the compression set after heating at 30 ° C. for 96 hours was measured, the compression set after heating at 130 ° C. for 96 hours was 37%. The results are summarized in Table 1. A heat aging test was performed in the same manner as in Example 1. Table 2-4 shows the results.
And FIGS.

[0104]

[Table 1]

[0105]

[Table 2]

[0106]

[Table 3]

[0107]

[Table 4]

As shown in Table 1, the heat of crystal fusion was 4
In Comparative Example 1 using chlorinated polyethylene (B) exceeding 0 J / g or in Comparative Example 2 in which only the melt-kneading was performed without performing dynamic crosslinking, the compression set was larger than that in Example 1. For this reason, it is difficult to apply the present invention to applications that require rubber elasticity to be maintained for a long period of time, particularly applications that are used at high temperatures.

Further, as shown in FIGS. 3 to 5, the molded article comprising the thermoplastic elastomer composition of the present invention described in Example 1 was composed of only the thermoplastic polyester elastomer (A) described in Comparative Example 3. Molded article made of
The heat aging resistance is greatly improved as compared with the molded article made of chloroprene rubber described in (1).

Further, when the thermoplastic elastomer composition of the present invention is used as a constant velocity joint boot for an automobile, it is possible to fix the thin joint boot with a thin metal band, and to use the thermoplastic elastomer composition in an automobile. It can contribute to weight reduction.

[0111]

The thermoplastic elastomer composition of the present invention can be melt-molded, and has mechanical strength, oil resistance, heat resistance,
It is a thermoplastic elastomer composition having excellent flexibility and compression set. Further, it has excellent heat aging resistance, and can be used in applications where it is placed under high temperature conditions for a long time. It is useful as a material for various joint boots, especially for constant velocity joint boots for automobiles.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of a fractured surface of a thermoplastic elastomer composition of Example 1.

FIG. 2 is an electron micrograph of a fracture surface of the thermoplastic elastomer composition of Example 2.

FIG. 3 is a graph showing a temporal change in tensile strength in a heat aging test.

FIG. 4 is a graph showing a change with time of elongation in a heat aging test.

FIG. 5 is a graph showing a temporal change of hardness in a heat aging test.

FIG. 6 is a sectional view of a constant velocity joint boot for an automobile.

FIG. 7 is a perspective view of a metal band.

[Description of Signs] 1 Constant velocity joint boot for automobile 2 Hollow part 3 Bellows shape 4 One end of boot 5 Other end of boot 6 Cylindrical part 7 Band mounting groove 8 Metal band 9 Ring band 10 Welding point 11 Tightening Metal plate 12 fixed blade

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Motoyuki Yokota 58 Kamitomii, Kurashiki-shi, Okayama Marugo Rubber Industries Co., Ltd. F-term (reference) 4F070 AA13 AA47 AB04 AB11 AB16 AB21 AB24 AC18 AC50 AC76 AE08 AE30 GA07 GA10 GB01 GB08 GC01 4F071 AA10 AA15 AA43 AA79 AA89 AE02 AE22 AF15Y AF18 AF45Y AF57Y AH07 AH17 4J002 AA043 AA053 AA063 AA073 BB24X BN003 CCFD4 CD193 CF03W CF05W CF06W CF07W EV08 FEKE 010 KE ger FD203 GM00 GN00

Claims (13)

[Claims] 1. A thermoplastic polyester elastomer (A), a chlorinated polyethylene (B) having a heat of crystal fusion of 40 J / g or less and a chlorine content of 15 to 45% by weight, and a crosslinking agent (C). A thermoplastic elastomer composition which is melt-kneaded and dynamically crosslinked. 2. A thermoplastic polyester elastomer (A) of 30 to 99 parts by weight and a chlorinated polyethylene (B) of 1 to 100 parts by weight of the total of the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B). ~ 7
0 parts by weight, 0.01 to 5 parts by weight of a crosslinking agent (C)
The thermoplastic elastomer composition according to claim 1, which is melt-kneaded. 3. A blend of 0.1 to 20 parts by weight of a compatibilizer (D) with respect to a total of 100 parts by weight of a thermoplastic polyester elastomer (A) and a chlorinated polyethylene (B), and melt kneading. The thermoplastic elastomer composition according to claim 1. 4. The compatibilizer (D) is a polymer containing an epoxy group, and the weight of the oxygen element derived from the epoxy group contained in the compatibilizer (D) is based on the weight of the thermoplastic polyester elastomer (A). The ratio is 1/10000 to 5/10
The thermoplastic elastomer composition according to claim 3, which is 00. 5. The thermoplastic resin according to claim 1, wherein 5 to 100 parts by weight of the basic substance (E) is blended with 100 parts by weight of the chlorinated polyethylene (B) and melt-kneaded. Elastomer composition. 6. The method according to claim 1, wherein the thermoplastic polyester elastomer (A) and the chlorinated polyethylene (B) are melt-kneaded in advance, and then the crosslinking agent (C) is blended and further melt-kneaded. A method for producing a thermoplastic elastomer composition according to the above. 7. A dry-blended or melt-blended chlorinated polyethylene (B) and a basic substance (E) are supplied to an extruder, melt-kneaded with a thermoplastic polyester elastomer (A), and then crosslinked. The method for producing a thermoplastic elastomer composition according to claim 5, wherein the agent (C) is blended and further melt-kneaded. 8. A twin-screw extruder is used when melt-kneading the thermoplastic polyester elastomer (A), the chlorinated polyethylene (B) and the crosslinking agent (C), and the average temperature of the cylinder of the twin-screw extruder is determined. 150 to 200 ° C., and a linear velocity of 5 to 25 m / min.
The method for producing a thermoplastic elastomer composition according to claim 6 or 7, wherein the molten resin at 30 ° C is discharged. 9. The L / L of the screw of the twin screw extruder used
D is 20 or more, and the ratio of the length of the kneading portion to the entire length of the screw is 2/100 to 30/10
The method for producing a thermoplastic elastomer composition according to any one of claims 6 to 8, which is 0. 10. A molded product obtained by melt-molding the thermoplastic elastomer composition according to claim 1. 11. Tensile strength in a heat aging test in air at 150 ° C. shows a minimum value between 20 and 300 hours after the start of the test, and then increases, and after 500 hours, the tensile strength before the test. 11. A value of 50% or more of
The molded article as described. 12. The molded product according to claim 10, wherein the molded product is a joint boot. 13. The molded product according to claim 10, wherein the molded product is a joint boot arranged to cover a constant velocity joint on an engine side of an automobile.