KR970000326B1 - Joint boots - Google Patents

Abstract

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Description

Joint booth

1 is a half sectional view showing a state where the joint booth of the present invention is fitted to a joint.

2 is a perspective view showing a one-touch band for fixing the joint booth of the present invention.

3 is a perspective view showing a one-touch band which is preferably used when fixing a boot made of a thermoplastic polyester elastomer.

4 is a sectional view of a joint boot molded body obtained in Example 1. FIG.

FIG. 5 is a sectional view of a joint boot molded body obtained in Example 2. FIG.

6 is a sectional view of a joint boot molded body obtained in Example 3. FIG.

7 is a sectional view of a joint boot molded body obtained in Example 4. FIG.

8 is a sectional view of a joint boot molded body obtained in Example 5. FIG.

9 is a sectional view of a joint boot molded body obtained in Example 1. FIG.

* Explanation of symbols for main parts of the drawings

1: large diameter sphere 2: small diameter sphere

3: wrinkle portion 4: valley portion

5: Mountain part 9a, 9b: Both tilting part

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to joint boots made of thermoplastic polyester elastomer compositions, and more particularly to corrugated joint boots that can be suitably used in, for example, constant velocity joints of automobiles.

BACKGROUND ART Conventionally, a joint of a vehicle or an industrial machine is fitted with a boot to protect and support the grease enclosed or to prevent dust or the like.

And such a joint booth was manufactured by injection molding rubber materials, such as chloroprene rubber.

However, in recent years, the use of automobiles is required to prolong the warranty period of parts (from 3 to 5 years). As the rubber materials described above have problems in ozone resistance and abrasion resistance, The use of thermoplastic polyester elastomers in place of chloroprene rubbers has changed, and the wonderful ozone and wear resistances have allowed a five year warranty.

However, when making the boot molding agent using the thermoplastic polyester elastomer described above, the yield elongation is low (59-70%) as compared with the conventional rubber material, so that the number of acids in the corrugated box is increased to increase the amount of the film. It was necessary to make the length, and since the elastic modulus was high, it was necessary to make the film thickness into the range of about 0.7-1.8 mm.

In order to make the boot molded body of the above shape by injection molding the thermoplastic polyester elastomer, since the elastic modulus of the thermoplastic polyester elastomer is high, the mold release during the molding is difficult and the undercut to the boot shape is difficult. Special studies were needed to study the undercut ratio, the taper angle to be pulled out, or to divide the center of the mold. Moreover, although it can shape | mold, since plastic deformation or a complicated mold release method should be employ | adopted, productivity may fall.

Therefore, when manufacturing a boot molded body using thermoplastic polyester elastomer, a blow molding method such as a direct blow method or an injection blow method has been generally used.

However, such a blowing molding method had the following problems. For example, in the case of a direct blow method in which a cylindrical parison pushed out by a screw or the like is expanded in a mold to obtain a molded article, a parison control that controls the thickness of the extrusion parison may be used. In forming the wrinkled body, the thickness of the peak portion and the valley portion does not become uniform. In addition, even in the case of the injection blow method in which a molten resin is injected to form a tubular shaped product, and air is blown therein to obtain a molded product, it is also very difficult to increase the precision of the inner surface of the molded product. In other words, making the boot-molded body uniform in thickness is a very important problem in terms of function, and has a great influence on the durability life.

In the blow molding method, even if the above problems are solved by improving the molding machine using precise parison control or the role of a mandrel, for example, the rigidity of the thermoplastic polyester elastomeric joint boot molded body is inserted into the joint. When attaching, it causes many problems. That is, since elastic modulus is high, it is easy to deform | transform, and productivity falls, and the force applied to a fixing band part at the time of boot deformation increases. In addition, in the thermoplastic polyester elastomer single body boot, the compressive permanent strain decreases, so that the tension-bonding force also decreases in the small diameter fixing portion when the boot is used.

Therefore, thermoplastic polyester can not be used as a simple one-touch band for rubber boot in conventional elastomeric booths, but more rigid fixing bands must be used, which must be clamped in a special way, and in many production processes. There is a load.

As described above, the joint boot molded body made of a thermoplastic polyester elastomer is excellent in mechanical properties, oil resistance, heat resistance, durability, etc., but it is difficult to be injection molded due to the high rigidity of the material. There are restrictions. In addition, when the blowing molding method is used, the thickness of the pleats is not uniform, and special studies must be conducted to secure the durability of the joint boot molded body. In addition, there is a disadvantage in that the flexibility and compression set strain are poor, which makes it impossible to use a simple band for rubber boots.

MEANS TO SOLVE THE PROBLEM As a result of repeating research in order to solve the above-mentioned problem, the inventors mix | blend a specific amount of rubber with thermoplastic polyester elastomer, and in some cases, perform a dynamic crosslinking, and lower oil resistance and heat resistance. The present invention provides a thermoplastic polyester elastomer composition having improved flexibility and compression set without straining. In addition, as a result of intensive examination, it has been found that by injection molding the composition, a joint boot having a desired shape can be obtained. It was.

Further, the inventors of the present invention have examined the joint booth, and as a result, they have a durability comparable to that of a joint boot molded body made of a thermoplastic polyester elastomer alone, and can be fixed by a simple one-touch band for a rubber booth. To provide a joint booth.

That is, this invention injects the (C) thermoplastic polyester elastomer composition which has the flexibility by mix | blending 80-1 weight% of (B) rubber to 20-99 weight% of (A) thermoplastic polyester elastomers, It is to provide a joint booth which can be obtained by molding. In addition, the "joint" to which the joint booth of the present invention is applied refers to a joint which is a free part constituting a connection portion between a drive shaft and a wheel and a drive force transmission system in an automobile or an industrial machine.

The thermoplastic polyester elastomer (A) is a block copolymer composed of a high melting point polyester segment and a low melting point polymer segment.

The aromatic polyester unit of the high melting point crystalline segment (A-1), which is a hard segment, is formed of an acid component and a glycol component, which are substantially terephthalic acid and / or 2,6-naphthalenedicarboxylic acid. In addition to terephthalic acid or 2,6-naphthalenedicarboxylic acid, other aromatic dicarboxylic acids such as isophthalic acid or aliphatic dicarboxylic acids such as adipic acid, sebacic acid, cyclohexane-1,4-dicarboxylic acid, dimer acid, You may use together a small amount.

The glycol component forming the aromatic polyester unit is a glycol having 2 to 12 carbon atoms, such as ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanediol, decanediol and the like.

The aliphatic polyether unit constituting the low melting point polymer segment (A-2), which is a soft segment, is formed of polyalkylene glycol. Specific examples of the polyalkylene glycol include, for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol. And polyethylene glycol-polypropylene glycol block copolymers, and the like, and polytetramethylene glycol is particularly preferable. These polyalkylene glycols may be used alone or as a mixture as long as the ratio of their carbon number and oxygen number is 2-4.5.

Another unit constituting the low melting polymer segment (A-2), the aliphatic polyester unit mainly consists of aliphatic dicarboxylic acid and glycols, the main acid component of the aliphatic dicarboxylic acid is, for example, succinic acid, adipic acid, seba Sinic acid, decandicarboxylic acid, and the like. Moreover, you may use together a small amount of aromatic dicarboxylic acids, such as isophthalic acid, in addition to these aliphatic dicarboxylic acids.

Moreover, the glycol component which forms the said aliphatic polyester unit is a C2-C12 glycol component, and the specific example is illustrated as the glycol component which forms the aromatic polyester unit of a high melting-point crystalline segment (A-1). Such as those listed.

The aliphatic polyester unit is obtained by polycondensing the aliphatic dicarboxylic acid and a glycol component in a conventional manner, and may be homopolyester or copolyester, or polylactone obtained by ring-opening a ring-shaped lactone (for example, poly -ε-caprolactone). The upper limit of the melting point of the low melting polymer segment (A-2) is not particularly limited, but is generally 130 ° C. or lower, preferably 100 ° C. or lower. Moreover, the molecular weight of the low melting polymer segment (A-2) is 400-6000 normally.

The composition ratio of the high melting point crystalline segment (A-1) and the low melting point polymer segment (A-2) in the thermoplastic polyester elastomer (A) is preferably 95 / 5-5 / 95 in weight ratio, more preferably Is 70 / 30-30 / 70. Moreover, it is especially preferable that a softening point is 100 degreeC as thermoplastic polyester elastomer (A).

The polyester block copolymers particularly preferably used as the thermoplastic polyester elastomer (A) are polytetramethylene terephthalate or polytrimethylene terephthalate-2,6-na as high melting point crystalline segments (A-1). Phthalate is used, and it is formed using polyethers, such as polyether, such as polytetramethylene glycol, polytetramethylene adipate, and poly- (epsilon) -caprolactone, as low melting-point polymer segment (A-2). Moreover, the polyfunctional hydroxy compound, the oxy acid, etc. may be copolymerized as a part of dicarboxylic acid or glycol.

These polyfunctional components effectively work as high viscosity components by copolymerizing in the range of 3 mol% or less. Examples of the polyfunctional component include trimellitic acid, trimesic acid, pyromellitic acid, benzophenoltetracarboxylic acid, butanetetracarboxylic acid, glycerin, pentaerythritol or esters thereof and acid anhydrides.

The thermoplastic polyether elastomer (A) can be produced by a conventional polymerization method. Preferred methods include heating aromatic dicarboxylic acids or their dimethyl esters with low melting point segmented diols to about 150-260 ° C. in the presence of a catalyst, followed by esterification or transesterification, followed by excess in vacuo. A method of obtaining a thermoplastic elastomer by performing a polycondensation reaction while removing a low molecular diol, reacting with a terminal group of their prepolymers to a pre-adjusted high melting point polyester segment forming prepolymer and a low melting point polymer segment forming prepolymer After mixing and reacting a bifunctional chain extender, the method is obtained by retaining the system in a high vacuum to remove volatiles to obtain a thermoplastic polyester elastomer, by heating and mixing a high-polymerization high melting point polyester and lactones, By transesterification of the lactones by ring opening polymerization And a method of obtaining a plastic polyester elastomer.

As said rubber (B), various synthetic rubber and natural rubber can be used individually or in combination. Preferred rubbers (B) include polar diene rubbers and hydrogenated substances thereof, acrylic rubbers, hydrin rubbers, urethane rubbers, chlorophosphazene rubbers and thermoplastic polyurethane elastomers and thermoplastic polyamide elastomers. Moreover, since silicone rubber and fluorine rubber are oil-resistant, it is used suitably as a solid part (B).

In the present invention, particularly preferred rubbers (B) are non-halogen diene rubbers, hydrogenated materials of non-halogen diene rubbers, epichlorohydrin rubbers, and the like, and more specifically acrylonitrile-butadiene copolymer rubbers and hydrogenated acyrylonitrile. -Butadiene copolymer rubber, hydrogenated acrylic ester-butadiene copolymer rubber, ethylene-propylene copolymer rubber, etc.

The blending ratio of the thermoplastic polyester elastomer (A) and the rubber (B) in the thermoplastic polyester elastomer composition (C) is component (A) / component (B) = 99-20 / 1-80% by weight It is preferably 95-51 / 5-49% by weight, more preferably 85-55 / 15-45% by weight. If the amount of the component (A) is too large, the amount of the component (B) is insufficient as a result, so that the flexibility of the composition (C) obtained and the effect of improving the compression set are not sufficient. In order to anticipate sufficient effect, it is preferable that component (A) is 95 weight% or less. Moreover, when the usage-amount of a component (A) is less than 20 weight%, the workability and fluidity | liquidity of the composition (C) obtained are inferior, and it is not preferable as a joint booth material. Especially as injection molding material, it is preferable that component (A) is 51 weight% or more.

The thermoplastic elastomer composition (C) of the present invention can be obtained by simply blending the thermoplastic polyester elastomer (A) and the rubber (B), but in order to obtain a higher performance composition (C), the dynamic crosslinking To be implemented. Dynamic crosslinking refers to W.M. It is a method developed by Fischer or A.Y.Coran of Monsanto, and it refers to a method of blending rubber into a matrix of thermoplastic resin, highly crosslinking the rubber while kneading with a crosslinking agent, and further dispersing the rubber finely.

As the crosslinking agent used in the dynamic crosslinking, crosslinking agents such as peroxides, resin crosslinking agents and sulfuric acid used for ordinary rubbers can be used. As a specific example of a crosslinking agent, the crosslinking agent, a crosslinking adjuvant, a crosslinking promoter, etc. which are described, for example in the crosslinking agent handbook (Yamashida Shinzo, Kaneko Toge, Daisei Co.) are mentioned.

That is, in the present invention, 1,3-di (t-butylperoxy isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2, Crosslinking agents, such as 5-di (t-butylperoxy) hexane-3 and t-butyl cumyl peroxide, can be used preferably.

Although the addition amount of the said crosslinking agent changes with the performance calculated | required by the composition (C), and the kind of crosslinking agent used, it is 0.01-8 weight part normally with respect to 100 weight part of rubber (B). If more than 8 parts by weight, more crosslinking is not expected and is uneconomical, which is undesirable because undesirable side reactions such as decomposition of polymers are likely to occur. When less than 0.01 part by weight, sufficient crosslinking does not occur.

The dynamic crosslinking in the present invention is performed by training each of the above-described components by various extruders, short-barrel mixers, kneaders, or a combination thereof. However, when productivity is considered, it is most preferable to produce continuously using a twin screw extruder. At this time, a plasticizer and a crosslinking agent are added in the middle of an extruder.

In the case of the thermoplastic polyester elastomer (A) alone, its hardness is H _P : 45 or more (H _S : 96 pionts or more), and the tensile modulus at room temperature (23 ° C. ± 5) is 600 kgf / cm 2 or more. In contrast, the hardness of the thermoplastic polyester elastomer composition (C) blended with rubber (B) is H _D : 20-44 points (H _S : 60-95 points), and the tensile modulus is flexible to 400 kgf / cm 2 or less.

As the thermoplastic polyester elastomer composition (C) of the present invention, a tensile modulus of elasticity of 30-400 kgf / cm 2 is particularly preferable. Such thermoplastic polyester elastomer composition (C) uses polytetramethylene terephthalate or polytrimethylene terephthalate-2,6-naphthalate as the high melting point crystalline segment (A-1), and has a low melting point polymer segment. As (A-2), it forms using polyethers, such as polytetramethylene glycol, or polyesters, such as a polytetramethylene adipate and a poly- (epsilon) -caprolactone. Thermoplastic polyester elastomer (A), rubber (B) such as acrylonitrile-butadiene copolymer rubber, hydrogenated acrylonitrile-butadiene copolymer rubber, hydrogenated acrylic ester-butadiene copolymer rubber, and ethylene-propylene copolymer rubber It is obtained by performing dynamic crosslinking using the above-mentioned crosslinking agent, using the compounding ratio of (A) / component (B) = 85-55 / 15-45 weight%.

By using the composition (C) having a tensile modulus of 30-400 kgf / cm 2, a joint boot molding agent having good rotational expansion and internal pressure characteristics can be obtained. Moreover, when the composition (C) of 50-390 kgf / cm <2> of tensile elasticity modulus is used, caulking by the one-touch band of a molded object can be improved. The JIS A hardness of the composition (C) for obtaining a joint boot molded body having excellent rotational expansion and internal pressure characteristics is 60 point-95 points, preferably 65 point-95 points.

That is, when the tensile modulus and hardness of the composition (C) are below the above-mentioned ranges, the rotational expansion resistance is insufficient, and at the high speed rotation, the pleats of the boot-molded body expand by the rotation centrifugal force. In addition, the internal pressure characteristic is insufficient, the internal pressure of the boot-molded body decreases due to the drop in the ambient temperature, and the length of the wrinkled film is rolled up.

On the other hand, when the tensile modulus or hardness is above the above range, the object of the present invention cannot be achieved.

The tensile strength at break of the thermoplastic polyester elastomer composition (C) is preferably 50-300 kgf / cm 2, more preferably 60-280 kgf / cm 2, still more preferably 70-250 kgf / cm 2. Below 50 kgf / cm 2, the strength required for the joint boot molded body is insufficient, and at 300 kgf / cm 2 or more, sufficient flexibility cannot be obtained unless the rubber content is pressed as much as possible.

In addition, the compressive permanent strain of the composition (C) is 80% or less (JIS K) in order to enable the use of a simple and easy one-touch band, which is the object of the present invention, in order to prevent it from falling out of the small diameter of one of its uses. -6301, 120 degreeC 22 hours), More preferably, it is 75% or less, Especially preferably, it is 70% or less. The hardness was measured in accordance with ASTM D2240 using a Type D Shore Jurometer for the H _D hardness, and in accordance with JIS K6301 using a JIS A Type Jurometer for the H _S hardness. In addition, the tensile modulus of elasticity was calculated by the forced vibration non-resonance method at 23 ± 2 ° C or lower. The measurement was performed by applying a sinusoidal strain with a frequency of 10 Hz and a displacement amplitude of 3 μm to a specimen having a width of about 2 mm, a thickness of about 1 mm, and a length of about 30 mm, and obtaining the dynamic stress, dynamic displacement, and phase angle. It was performed by calculating the tensile tensile modulus of phosphorus.

E * =

E '= E * cos (P) [kgf / cm 2]

E *: complex modulus of elasticity [kgf / cm 2]

E ': dynamic tensile modulus of elasticity [kgf / cm 2]

CD: length of sample [cm]

DF: dynamic stress [gramf]

DD: Dynamic displacement [cm]

P: phase angle [deg]

W: Width of sample [cm]

T: thickness of the sample [cm]

In the present invention, the thermoplastic polyester elastomer composition (C) is injection molded. By manufacturing by injection molding, a joint boot molded body having a uniform thickness can be obtained.

It is preferable that the flowability of the composition (C) at the time of injection molding is more than 0.1 g / min (flowability measured under a 10 kg load) of MFR value in the flowability measurement of the molten polymer based on JISK-7210. If the MFR value is less than 0.1 g / min, fluidity in the mold is bad, and good shaping cannot be performed.

Preferably the injection molding conditions when the above injection molding

Screw speed: 100-400 rpm,

Cylinder temperature: 180-230 ℃,

Nozzle temperature: 210 ° C (near the melting point of the composition),

Injection pressure: 400-1600kgf / ㎠

Injection time: 1-3seconds,

Cooling time: 15-60seconds,

Mold temperature: 20-50 ℃

to be.

According to the joint booth of the present invention described above, a joint booth having a desired shape and structure can be provided.

Moreover, although the shape and structure of the joint booth of this invention are not specifically limited, According to the structure of the joint booth described below, it has the durability comparable to the joint booth which consists of thermoplastic polyester elastomers, A joint booth that can be fixed with a simple one-touch band for rubber boots can be obtained.

That is, according to the present invention, as shown in FIG. 1, the joint booth formed of the corrugation portion 3 having the valley portion 4 and the hill portion 5 between the large-diameter mouth portion 1 and the small-diameter mouth portion 2 is formed. Can be obtained, and the angles (α ₁ , α ₂ , α ₃ , α ₄ , α ₅ ) formed by the valley portions on the side of the large-diameter portion and the valley portions on the side of the valley-side portion adjacent to the valley portion are almost the same. In addition, a joint boot can be obtained in which the ratio of the diameters of the peak portion of the large-diameter portion to the peak portion of the small-diameter portion adjacent to the peak portion is 1: 1.00-0.50.

6, 6 is a joint socket, 7 is an annular groove, and 8 is a drive shaft. The angle formed by the both slopes of the valleys (hereinafter, referred to as the valley angle) is an angle α formed by a straight line drawn along both slopes 9a and 9b as shown in FIG. α ₂ ).

In the case where the joint booth is a constant velocity joint booth for automobiles, the maximum envelope connecting the vertices of the corrugated part in a monotonous curve is a space in which the constant velocity joint booth of the car is fitted, in the vicinity of a booth such as a stabilizer during normal and maximum deformation. The length of the membrane, the number of acids and the thickness of the membrane are determined by the minimum non-interfering space with the part and the amount of folding and widening of the wrinkles at the maximum operating angle.

Therefore, the number of peaks of the corrugations in the joint booth of the present invention is preferably 4 or more in the amount of widening at the maximum operating angle, and at the same time, in the film thickness of 0.5 mm or more, if it is not 9 or less in the amount of folding on the compression side. Many wears occur. Thus, the number of acids in the corrugations is 4-9, preferably 4-8, particularly preferably 5-7.

In the joint booth, the angle formed by the valley portion on the large-diameter portion and the inclined portion of the valley portion on the small-diameter portion adjacent to the valley portion is substantially the same, and the peak portion on the large-diameter portion side of the corrugation portion and the peak portion thereof Since the ratio of the outer diameter to the side of the adjacent small diameter sphere is 1: 1.00-0.50, the film of the wrinkle part is evenly contacted at the time of maximum deformation of the joint boot, and excellent wear resistance can be obtained.

The outer diameter of the maximum peak in the joint booth is preferably within 1.2 times the outer diameter of the joint outer ring due to the limitation of the space in which the boot molded body is fitted.

As the thickness d of the wrinkles, 0.5-2.5 mm is preferable because the elastic modulus of elasticity of the molten resin during injection molding and the tensile elastic modulus of the thermoplastic polyester elastomer composition (C) softened are 400 kgf / cm 2 or less. If the thickness of the crease is 0.5 mm or less, the rotational expansion and internal pressure characteristics are insufficient, resulting in a functional problem of the joint booth. If it is 2.5 mm or more, a large amount of wear occurs at the maximum operating angle even if the number of peaks in the crease is three.

The joint boot of the present invention is fitted by fixing the large diameter portion 1 and the small diameter portion 2 to the joint body by the one-touch band (hereinafter referred to as band A) shown in FIG.

The band A shown in FIG. 2 has the other end 13 attached to the protruding portion 12 extending from one end of the curved member 11 formed by bending a steel plate having a thickness of about 0.3 mm and a width of about 7 mm. It is made by screwing it. When the joint booth is fixed by the band A, the speaker 12 is folded in the direction of the arrow A, and this is fixed by bending the two standing pieces 14 formed at the predetermined portion of the curved member 11. do.

Since this operation can be easily performed with bare hands, it is very easy to fit the joint booth of the present invention.

The one-touch band (hereinafter referred to as band B) shown in FIG. 3 is a projection piece 15 at one end of the curved member 11 'formed by bending a steel plate having a thickness of about 0.4 mm to 0.7 mm and a width of about 10 mm. Is formed, and is engaged with the engaging hole 16 formed in the other end. The fixing of the joint booth by the band B simultaneously inserts the projection pieces 15 into the locking holes 16, and simultaneously tightens the fastening ears 18 formed at the predetermined portions of the curved member 11 'in both directions indicated by arrows B. It is supposed to be inserted.

Band B is preferably used, for example, when fixing a boot made of a thermoplastic polyester elastomer single body such as Hydorel®.

In the case of a boot made of a conventional thermoplastic polyester elastomer single body, since the elastic modulus is larger than 600 kgf / cm 2, the boot band member should be about 0.5-0.7 mm thick, and a corresponding crimping tool is required when tightening. It requires a lot of karate.

However, in the joint booth of the present invention, by using a flexible thermoplastic polyester elastomer composition containing rubber, its elastic modulus is 400 kgf / cm 2 or less, and the band A for rubber boot can be used. Difficulties in the process are greatly improved. That is, the joint boot of the present invention can be fixed to the joint body without using the band B.

The joint booth evaluation methods can be broadly divided into a boot durability test, a boot underpressure test, and a rotation expansion test. The boot endurance test was conducted at an ambient temperature of -5 ° C, the joint angle of 30deg, and the rotational speed of 400rpm. The grease was placed in the booth for 50 hours of continuous operation to determine the time (hrs) until the boot broke. . In this test, if failure does not occur even after 50 hours has elapsed, it is determined that the durability as a booth is satisfactory. The boot negative pressure test uses the inside of the joint as negative pressure and evaluates the shape or material at your boot strain. In the rotation expansion test, the amount of expansion at high speed is measured and evaluated by an optical microscope.

As a result, the joint booting strength, compressive permanent strain, heat resistance weather resistance, cold resistance, and grease resistance of the present invention obtained by injection molding the thermoplastic polyester elastomer composition containing rubber, fatigue resistance, abrasion resistance, etc. It is not only excellent in practical performance but also very flexible. Therefore, according to the joint booth of the present invention, since the flexibility and the compression permanent strain, which were the problems of the conventional thermoplastic polyester elastomeric single body joint boot molded body, are improved and flexible, even when the joint booth of a complicated shape is released from the mold, This becomes easy and injection molding becomes possible.

In addition, according to the present invention, since the joint boot molded body is made by injection molding, the degree of freedom in designing the joint boot shape can be increased, the precision of dimensions can be ensured, and the uniform joint boot of the film thickness can be obtained. Will be.

In addition, according to the joint boot with the specific shape of the present invention, the durability of the joint can be greatly improved, and even in the production process to be attached to the joint, it can be attached very easily because it is flexible, and there is little compression permanent strain, It can be fixed by a simple one-touch band for a rubber boot, and the performance can be remarkably improved compared to a joint booth made of a conventional thermoplastic polyester elastomer alone.

EXAMPLE

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these embodiments unless departing from the gist of the present invention.

Example 1

Using a twin-screw extruder at the ratios shown in Table 1 for thermoplastic polyester elastomers (Enigemu, Polymer, PIBIFLEX 46M) and acrylonitrile butadiene rubber (manufactured by Japan Synthetic Rubber, JSR NBR N230SV: NBR). To prepare a composition (C in Table 1) that was kneaded only at a rotational speed of 200 rpm at 210 ° C., and a composition (copper A and B) subjected to dynamic crosslinking by adding a crosslinking agent in the middle while kneading under the same conditions. The obtained pellets were sufficiently dried and then molded into a sheet having a thickness of 2 mm at an injection molding machine at 210 ° C., and subjected to each test.

In addition, in Table 1, the physical properties of the thermoplastic polyester elastomer alone (composition D) were also shown for comparison.

The test method used for the physical property evaluation is as follows.

(1) Liquidity: (MFR): 230 ℃ × 10㎏

(2) Hardness H _S : JIS K-6301 JIS A Hardness

H _D : ASTM D-2240 Shore D Hardness

(3) Tensile strength T _B : JIS K-6301 JIS No. 3 dumbbell

(4) Tensile elongation E _B : JIS K-6301 JIS No. 3 dumbbell

(5) Tensile modulus: as described above

(6) Heat aging resistance: Tensile strength after 300 hours was measured at 120 DEG C using a JIS K-6301 gear type aging tester, and expressed as a percentage of change in tensile strength before heat test.

(7) Oil resistance: JIS K-6301 After immersion in JIS No. 3 oil at 120 ° C. for 70 hours, the tensile strength was measured and expressed as the percentage of change in tensile strength before oil resistance test.

(8) Wear Resistance: ASTM D 1044 Tapered Wear CS-17 Foil 1000g Weight

(9) Compression permanent strain (JIS K-6301 120 ℃ 22hrs

1): PIBIFLEX 46M (Enigemu: Polyberry Co., Ltd.)

2): JSR NBR N230SV (made by Japan Synthetic Rubber)

3): Palnock PM (made by Dicing Inc.)

4) Gyahexa AD

Next, the composition A-C shown in Table 1 was injection-molded under the following conditions, and the joint boot molding 1 shown in FIG. 4 was shape | molded.

Injection molding condition

Screw Speed: 1000rpm

Cylinder temperature: 210 ℃

Nozzle Temperature: 210 ℃

Injection pressure: 800kgf / ㎠

Injection time: 2seconds

Cooling time: 20seconds

Mold temperature: 40 ℃

As shown in the drawing, the obtained joint boot molded body 1 was a corrugated box in which a corrugation portion 23 was formed between the large-diameter mouth portion 21 and the small-diameter mouth portion 22. The corrugations 23 are formed with four valleys 24, 24, 24, 24 and four hills 25, 25, 25, 25, and the valley angles of the four valleys 24 ( All of?,?,?,?) were almost identical. Moreover, the outer diameter of the mountain part 25, 25, 25, 25 was almost the same, and ratio of the outer diameter R of the mountain part 25 and the outer diameter R of the mountain part 254 was almost 3: 2. Moreover, the film thickness d of the wrinkle part was 1.0 mm.

After evaluating the injection moldability of the obtained joint boot-molded body 1, it stuck to the registration joint for automobiles similarly to the case shown in FIG. 1, and evaluated the fastening property high durability life at that time.

The criteria for evaluation are as follows.

1. Injection molding:

It was said that injection molding was good when there was no short shot and the appearance was not bad (Promark, Delamination).

2. Tightness:

Using the band A shown in FIG. 2 and the band B shown in FIG. 3, the state when the large diameter part 21 and the small diameter part 22 of the molded object 1 were fastened and evaluated was evaluated based on the following reference | standard.

(Circle) shows the case where it can be tightened easily barely about band A, there is no problem, such as sealing property, and it is tightened using a crimping jig about band B, and there is no problem, such as sealing property.

× indicates that the band J can not be tightened with the bare hand, and a crimping jig is required, the band breaks when tightened, or the sealability is a problem. In addition, when the clamping is impossible, the case where the band is broken or when the sealing problem is caused is indicated.

3. Endurance Life:

The durability life at the time of sticking using band A was evaluated by the method mentioned above on condition of the following.

Atmosphere temperature: -5 ℃

Joint working angle: 30deg

RPM: 400rpm

Evaluation method: Grease is put in the booth and operated continuously for 50 hours, and the time (hrs) until breakage occurs in the booth is calculated. Even if 50 hours passed, breakage did not occur and the durability as a booth was judged to be satisfactory. The evaluation results of the physical properties are shown in Table 2.

Example 2

As shown in FIG. 5, except that five valleys 24, 24, 24, 24 and five hills 25, 25, 25, 25, 25 are formed in the pleats 23, as shown in FIG. The joint boot molded body II similar to the joint boot molded body I was injection molded, and the physical properties thereof were evaluated. The evaluation result of the physical property is shown in Table 2.

Example 3

As shown in FIG. 6, five valleys 24, 24, 24, 24 and 24 and five hills 25, 25, 25, 25 and 25 are formed in the pleats 23. The joint boot molded bodies III which were almost the same as the joint boot molded bodies I were obtained except that the outer diameter ratios were R: R = 1: 0.92, R: R = 1: 0.913, R: R = 1: 0.84, and R: R = 1: 0.83. . The evaluation results of the physical properties are shown in Table 2.

Example 4

As shown in FIG. 7, five valleys 24, 24, 24, 24, 24 and five hills 25, 25, 25, 25, 25 are formed in the pleats 23. The joint boot molded bodies IV which were almost the same as the joint boot molded bodies I were obtained except that the outer diameter ratios were R: R = 1: 0.973, R: R = 1: 0.972, R: R = 1: 0.928, and R: R = 1: 0.877. . The evaluation results of the physical properties are shown in Table 2.

Example 5

As shown in FIG. 8, five valleys 24, 24, 24, 24, 24 and six hills 25, 25, 25, 25, 25, 25 are formed in the pleats 23. The joint boot molded body except that the outer diameter ratio of the mountain part is R: R = 1: 0.932, R: R = 1: 0.9273, R: R = 1: 0.922, R: R = 1: 0.864, R: R = 1: 0.843 A joint boot molding V nearly identical to that of I was obtained. The evaluation results of the physical properties are shown in Table 2.

Comparative Example 1

The joint boot-molded article VI shown in FIG. 9 was obtained in almost the same manner as in Example 1 except that the composition D shown in Table 1 was used. In the obtained molded article VI, three valleys 24, 24, 24 and three peaks 25, 25, 25 are formed in the pleats 23, and the angles α, α, and α of the valleys are all different. The outer diameter ratios of the pregnant women were R: R = 1: 0.84 and R: R = 1: 0.82. The evaluation results of the physical properties are shown in Table 3.

Comparative Example 2-6

Except for using the composition D shown in Table 1, under the same conditions as in Example 1-5, a joint booth having the same shape as the joint boot molded body I-V obtained in Example 1-5 was injection molded, but the booth shape was maintained. It was not possible to release the mold with a blank. The evaluation results of the physical properties are shown in Table 3.

.

As apparent from the results shown in Tables 2 and 3, the molded article I-V obtained in Example 1-5 contains rubber, so that the joint obtained by injection molding the flexible thermoplastic polyester elastomer composition is molded. It is made of booths, all can be fixed with band A, and the boot life is sufficient.

On the contrary, the molded article VI obtained in Comparative Example 1 cannot be fixed in the band A. In Comparative Example 2-6, the molded articles I-V could not be released while maintaining the boot shape, and could not be fixed in the band A.

Claims (9)

(A) A joint booth obtained by injection molding a thermoplastic polyester elastomer composition having a flexibility obtained by blending 80-1% by weight of rubber with 20-99% by weight of thermoplastic polyester elastomer. The joint boot according to claim 1, wherein the tensile elastic modulus of the thermoplastic polyester elastomer composition is 30-400 kgf / cm 2. The joint boot according to claim 1, wherein the tensile breaking strength of the thermoplastic polyester elastomer composition is 50-300 kgf / cm 2. The joint boot according to claim 1, wherein the compressive permanent strain of the thermoplastic polyester elastomer composition is 80% or less. The joint boot according to claim 1, wherein the thermoplastic polyester elastomer composition has a tensile modulus of 30-400 kgf / cm 2, a dynamic tensile breaking strength of 50-300 kgf / cm 2, and a dynamic compression strain of 80% or less. The joint booth according to any one of claims 1 to 5, wherein the joint booth is formed of a corrugated portion having a valley portion and a hill portion between the large-diameter portion and the small-diameter portion, and is adjacent to the valley portion on the large-diameter portion side and the valley portion. The angle formed by both inclined portions of the valley portion on the small-diameter portion is almost the same, and the ratio of the outer diameter of the portion on the large-diameter portion side and the portion on the small-diameter portion adjacent to the portion is 1: 1.00-0.55. Joint boot. 7. The joint booth according to claim 6, wherein the number of the peaks of the corrugations is 4-9. The joint boot according to claim 6, wherein the wrinkle portion has a thickness of 0.5-2.5 mm. The joint booth according to claim 6, wherein the number of the peaks of the wrinkles is 4-9, and the thickness of the wrinkles is 0.5-2.5 mm.