JP2007010043A - Resin boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin boot formed of a thermoplastic elastomer resin with injection molding, superior in durability and usable under severe conditions as a constant velocity joint boot. <P>SOLUTION: The resin boot comprises a pair of mounting parts opened to both ends of a large diameter mounting part 3 and a small diameter mounting part 2, and a bellows part 4 integrally connecting the large diameter mounting part 3 and the small diameter mounting part 2 to each other and having a diameter gradually smaller as tending from the large diameter mounting part 3 to the small diameter mounting part 2. It is formed of the thermoplastic elastomer resin with injection molding. An inner diameter d<SB>3</SB>of a valley portion 5c nearest the large diameter mounting part 3 is larger than an opening diameter D<SB>1</SB>of the bellows part 4 on the side of the small diameter mounting part 2 and 60% or less of an opening diameter D<SB>2</SB>on the side of the large diameter mounting pat 3. A curvature radius R of the valley portion 5c is 2-10mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bellows-like resin boot used as, for example, a constant velocity joint boot mounted on an automobile axle or the like, and more particularly to a resin boot manufactured by injection molding of a thermoplastic elastomer resin.

  The constant velocity joint boot for automobiles has no speed difference between the input drive shaft and the output drive shaft, such as between the transmission of the vehicle and the propeller shaft, between the differential gear and the drive shaft, and between the drive shaft and the wheel. A cover that covers the joint portion having a structure that rotates at an equal speed, and prevents foreign matter from entering the joint portion, and also has a function of enclosing lubricating oil (grease). For example, as shown in FIG. 12, the constant velocity joint boot has a small-diameter mounting portion 2 attached to the outer periphery of the shaft and a non-circular outer periphery having three recesses such as a triport type constant velocity joint. A large-diameter attachment portion 3 attached to the outer case, and a bellows portion 4 integrally connecting the two, and the diameter of the bellows portion 4 gradually increases from the large-diameter attachment portion 3 toward the small-diameter attachment portion 2. It is smaller and has a generally truncated cone shape as a whole. The joint part on the axle of an automobile as described above is used under severe conditions in which it is repeatedly bent while rotating at a high speed, so that it does not expand (deform) due to the centrifugal force generated by the high-speed rotation (shake resistance) Both) and flexibility to withstand bending are required at the same time.

  Conventionally, the constant velocity joint boot is generally manufactured by injection molding of chloroprene rubber (Patent Document 1). However, chloroprene rubber is a vulcanized rubber and cannot be recycled. Therefore, boots made by blow molding of a recyclable polyester resin have been used. However, since polyester resins are generally hard and brittle and lack flexibility, to satisfy the flexibility required for constant velocity joint boots, it is necessary to form ridges and valleys in multiple stages in the bellows, If the crests and troughs are formed in multiple stages, the curvature radius of the troughs becomes small, and if it is repeatedly bent, cracks easily occur and cause breakage, so there is a problem in durability (fatigue). Resin boots manufactured by injection molding of thermoplastic resins are also known (see, for example, Patent Documents 2 and 3). However, in the case of a resin boot manufactured by injection molding of a thermoplastic resin, especially in a boot made of a thermoplastic elastomer having high flexibility, if the thickness of the bellows portion is thin, stress is concentrated due to centrifugal force during rotation. There is a risk that the ridges and valleys may crack and break, or the boots may expand and touch the surroundings. In order to prevent such damage and expansion of the boot due to centrifugal force, for example, as shown in FIG. 13, the thickness of the valley portion 5 and the peak portion 6 may be increased. However, when the wall thickness is increased, the accordion portion becomes hard, which causes problems in flexibility and durability. In addition, increasing the wall thickness increases the amount of molding material used and increases costs. As a method of improving the durability of such constant velocity joint boots, based on numerical values of various design factors such as the thickness ratio of the ridges and valleys in the bellows part (bellows part), the curvature radius of the ridges, and the pitch ratio. There has been proposed a method of setting a numerical value of the design element by calculating a characteristic value and comparing it with a limit characteristic value (see Patent Document 4). However, a concrete resin boot having flexibility and durability equivalent to those made of chloroprene rubber has not been provided.

FIG. 14 shows an example of a resin boot that is excellent in durability and can be used even under severe conditions as a boot for a constant velocity joint without impairing the flexibility that is a characteristic of a thermoplastic elastomer. A resin boot having a specific bellows shape has been proposed previously (Japanese Patent Application No. 2005-132203). This resin boot 1 is made of a thermoplastic elastomer from a gate provided on one attachment portion side of a pair of attachment portions 2 and 3 opened at both ends of a small-diameter attachment portion 2 and a large-diameter attachment portion 3 into a mold forming space. It is formed by injecting resin, and each valley portion 5 in the bellows portion 4 is equal to or thicker than the thickness of the peak portion 6 adjacent to each valley portion 5 near the mounting portion on the gate side. It is formed, and at least some of the valleys 5 are formed thicker than the adjacent peaks 6. This resin boot 1 is superior in flexibility and durability as compared with conventional resin boots.
Japanese Patent Laid-Open No. 4-92166 JP-A-6-190878 JP 2003-329059 A JP 2001-116057 A

  The present invention is superior in flexibility and durability even if the bellows portion is thinner than the resin boot previously proposed by the present inventors, and can be used as a constant velocity joint boot under severe conditions. It is intended to provide boots.

  As a result of further examination of the resin boot, the present inventors have a large-diameter mounting portion, a small-diameter mounting portion, and a bellows portion formed by integrally connecting the both, and the bellows portion is attached from the large-diameter mounting portion to the small-diameter mounting portion. In the resin boot made by injection molding with thermoplastic elastomer resin, the inner diameter of the valley portion closest to the large diameter mounting portion in the bellows portion is smaller than that of the conventional one. Resin boots with excellent flexibility and durability that can withstand use under harsh conditions that are repeatedly bent while rotating at high speed, such as constant velocity joint boots. It has been found that durability can be further improved by further increasing the radius of curvature of the valley, and the present invention has been completed.

That is, the resin boot according to the present invention is formed by integrally connecting a pair of attachment portions opened at both ends of the large-diameter attachment portion and the small-diameter attachment portion, and the large-diameter attachment portion and the small-diameter attachment portion. And a bellows portion that gradually decreases in diameter from the portion toward the small-diameter mounting portion, and is a resin boot formed by injection molding with a thermoplastic elastomer resin, the inner diameter of the valley portion closest to the large-diameter mounting portion d is larger than the opening diameter D ₁ on the small diameter attachment portion side in the bellows portion and 60% or less of the opening diameter D ₂ on the large diameter attachment portion side in the bellows portion, and the valley portion closest to the large diameter attachment portion The curvature radius is set to 2 mm to 10 mm.

  In the present invention, the bellows portion in the longitudinal section of the boot means a shape in which convex portions projecting toward the outer side of the boot and concave portions projecting toward the inner side of the boot are alternately continued, and is independent of the outer peripheral surface of the boot. A plurality of protruding ridges and recessed ridges are alternately formed, the peak is a protruding part of the bellows part, and the valley is a concave part. Moreover, the curvature radius of the said trough part is a curvature radius of the inner surface of the recessed part which protruded toward the inner side in the bellows part in the longitudinal cross-section of the said boot.

Wherein the outer diameter of the nearest crest in part with the large-diameter, is preferably smaller than the opening diameter D ₂ of the large-diameter mounting portion side of the bellows portion.

  The wall thickness of the bellows part is preferably 3 mm or less.

  It is preferable to form a cylindrical peripheral wall portion extending in parallel with the axis at the opening edge of the bellows portion on the large diameter attachment portion side.

  Moreover, although there is no limitation in particular in the kind of thermoplastic elastomer resin used by this invention, what contains (A) acrylic block copolymer is preferable, Furthermore, (A) acrylic block copolymer and ( B) A thermoplastic elastomer containing an olefinic thermoplastic elastomer, particularly a thermoplastic elastomer composition containing (C) a compatibilizer in addition to the above (A) and (B) is preferable.

As a preferred embodiment of the thermoplastic elastomer composition,
(A) 100 parts by weight of acrylic block copolymer, (B) 50 to 600 parts by weight of olefin thermoplastic elastomer, (C) 5 to 50 parts by weight of compatibilizer,
The (A) acrylic block copolymer comprises an acrylic polymer block (a) and a methacrylic polymer block (b), and has at least one polymer block having a reactive functional group (c). ,
The reactive functional group (c) in the acrylic block copolymer (A) has the general formula (1):

(Wherein R ¹ is a hydrogen atom or a methyl group, and may be the same or different, p is an integer of 0 or 1, q is an integer of 0 to 3) Having (c1) and / or a unit (c2) containing a carboxyl group,
The thermoplastic elastomer composition contains 0.1 to 50% by weight of a carboxyl group-containing unit (c2) in the entire acrylic block copolymer (A),
The acrylic block copolymer (A) contains 50 to 90% by weight of the acrylic polymer block (a) and 50 to 10% by weight of the methacrylic polymer block (b).
The acrylic block copolymer (A) is a block copolymer produced by atom transfer radical polymerization,
The olefinic thermoplastic elastomer (B) is a dynamically crosslinked EPDM rubber or acrylonitrile-butadiene rubber in an olefin resin. The compatibilizer (C) is an olefinic thermoplastic resin containing an epoxy group. .

In general, resin boots such as constant velocity joint boots are formed such that the diameter of the bellows portion is gradually reduced from the large diameter attachment portion toward the small diameter attachment portion. Resin boot according to the present invention, most having a larger inner diameter within the valleys of the bellows portion, the inner diameter d of the nearest troughs in part with the large-diameter, greater than the opening diameter D ₁ of the small-diameter attaching portion side of the bellows portion In addition, the opening is smaller than 60% of the opening diameter D ₂ on the large diameter attachment portion side in the bellows portion. By reducing the inner diameter d of the valley portion closest to the large-diameter mounting portion, the inner diameters of other valley portions whose diameters are gradually reduced toward the small-diameter mounting portion are inevitably reduced. The smaller the inner diameter of the valley of each step, the smaller the angular velocity during rotation, and the smaller the centrifugal force acting on each valley. As a result, the boots have excellent runout resistance and durability.

  Of the valley portions of the bellows portion of the resin boot, the valley portion closest to the large-diameter mounting portion has the largest inner diameter, so that the largest centrifugal force acts by rotation. Therefore, by increasing the curvature radius of the valley portion to 2 to 10 mm, the stress concentrated on the valley portion is dispersed by the centrifugal force at the time of rotation, and cracking due to bending can be prevented, and the curvature radius of the valley portion can be prevented. The larger the angle, the larger the angle between the two slopes sandwiching the valley with respect to the boot axis, the smaller the angle between the direction of centrifugal force acting and the inclined surface, and the less the expansion of the boot due to the centrifugal force during rotation. Durability is improved.

Further, the outer diameter of the nearest crest in part with the large-diameter is made smaller than the opening diameter D ₂ of the large-diameter mounting portion side of the bellows portion, the outer diameter of the crests of the bellows portion is small, the ridges Centrifugal force acting on is also reduced. As a result, the boots have excellent runout resistance and durability.

  Since the resin boot of the present invention has a small inner diameter of the bellows portion and the peak portion of the bellows portion as described above and has excellent anti-rotation property, even if the wall thickness of the bellows portion is reduced to 3 mm or less, etc. The durability required as a fast joint boot can be satisfied. Further, by reducing the thickness of the bellows portion in this way, it is lightweight and excellent in flexibility, and the amount of thermoplastic elastomer resin used for molding is small, and the manufacturing cost can be reduced.

  Further, as in each boot 1 shown in FIGS. 12 to 14, when the peak portion 6 d is formed so as to protrude outward from the opening edge on the large-diameter mounting portion 3 side in the bellows portion 4, the diameter of the peak portion 6 d becomes large and rotates. It is easy to expand by centrifugal force. However, when the valley portion is formed inward from the opening edge, the inner diameter of the bellows portion 4 on the large-diameter mounting portion 3 side becomes too small, and the shaft is formed on the inner surface of the bellows portion 4 when the joint is bent. It becomes easy to touch. By forming a cylindrical peripheral wall portion extending parallel to the shaft center at the opening edge of the bellows portion on the large diameter attachment portion side, expansion due to centrifugal force during rotation can be suppressed, and as described above Even if the inner diameter of the valley part closest to the part is reduced, the inner surface of the bellows part can be prevented from touching when the joint is bent, and the inner diameter of the valley part closest to the large-diameter mounting part can be reduced and rotated. Expansion at the time can be suppressed.

  Embodiments of the present invention will be described in detail with reference to the drawings based on examples, but the present invention is not limited thereto.

  Fig.1 (a) is a longitudinal cross-sectional view of the resin boots 1 which concern on embodiment of this invention. The resin boot 1 is a boot for a constant velocity joint of an automobile, and includes a small-diameter mounting portion 2 that is attached to a drive shaft, a large-diameter mounting portion 3 that is attached to an outer case, and a trough (concave portion) 5. The small-diameter attaching part 2 and the large-diameter attaching part 3 are provided with the bellows part 4 which is integrally connected to the large-diameter attaching part 3 in a shape in which the mountain parts (projected ridge parts) 6 are alternately continued. As shown in FIG. 2, the large-diameter mounting portion 4 has a plurality of inner peripheral surfaces such as a triport type constant velocity joint so that the large-diameter mounting portion 4 can be attached to a non-circular outer shape outer case having three recesses. The non-circular shape in which the convex part 7 was formed may be sufficient.

  In the boot 1 shown in the figure, the bellows portion 4 is formed with three valleys 5a to 5c and three peaks 6a to 6c. The number of troughs 5 and crests 6 is not particularly limited, but the number of crests 6 is preferably 3 to 5 from the viewpoints of processability of injection molding and expandability during rotation. When there are fewer than three peaks, it may be difficult to remove the mold after injection molding. On the other hand, when the number of ridges is more than five, the pitch between adjacent ridges 6 is narrowed, resulting in a decrease in the radius of curvature R of the valley 5 and stress due to centrifugal force during rotation, causing cracks. It tends to occur.

The boot 1 has a substantially truncated cone shape as a whole, and the bellows portion 4 has a trough portion 5 and a ridge portion 6 with diameters gradually decreasing from the large diameter attachment portion 3 toward the small diameter attachment portion 2. In the present invention, the inside diameter d ₃ of the closest to the large diameter mounting part 3 valleys 5c, the opening diameter of the large diameter mounting portion 3 side of the bellows portion 4, that is, the boot 1 of the illustrated example, the bellows portion 4 larger than the opening diameter D ₁ of the small-diameter attaching portion 2 side, and less than 60% of the inner diameter D ₂ of the large diameter mounting portion 3 side of the cylindrically formed peripheral wall portion 8 extending parallel to the axis X of the boot 1 on the opening edge Formed.

The boot 1 is formed so that the diameter of the bellows portion 4 from the large-diameter attachment portion 3 toward the small-diameter attachment portion 2, that is, the diameters of the valley portions 5 and the crest portions sequentially decreases. The smaller the inner diameter d ₁ of the nearest valley portion 5a, the smaller the inner diameters d ₂ and d ₃ of the valley portions 5b and 5c of each step formed so that the diameter is gradually reduced toward the small-diameter mounting portion 2. Become. Then, the boot 1 of the present invention, the inside diameter d ₃ of the nearest troughs 5c the large diameter mounting portion 3, are reduced to less than 60% of the inner diameter D of the edge portion of the large diameter mounting portion side of the bellows portion 4 As a result, the angular velocity of the valleys 5a, 5b, 5c of each stage during rotation is small, and the centrifugal force that acts is also reduced accordingly. As a result, the boot 1 is excellent in anti-swing resistance and durability.

  Further, the radius of curvature R of the valley portion 5c is increased from 2 to 10 mm as shown in FIG. 2 (c), for example, as shown in FIG. The stress concentrated on the portion 5c is dispersed, and cracking due to bending can be prevented. Further, as the radius of curvature of the valley portion 5c increases, the angle between the two inclined surfaces 4a and 4b sandwiching the valley portion 5c with respect to the boot axis X increases, and the angle between the direction of centrifugal force acting and the inclined surfaces 4a and 4b increases. The inclined surfaces 4a and 4b are less likely to expand due to the centrifugal force during rotation, and the durability is improved.

Further, the large diameter mounting portion of the outer diameter of the nearest crest 6c to, is made smaller than the opening diameter D ₂ of the large-diameter mounting portion side of the bellows portion, the outer diameter of the crest portion 6a~6c the bellows portion 4 The centrifugal force acting on the boot 1 is also reduced, and the boot 1 is further excellent in anti-swing resistance and durability.

Further, as shown in the figure, a cylindrical peripheral wall portion 9 extending in parallel with the shaft core X is formed at the edge on the large-diameter mounting portion 3 side, and the inner side of the boot is defined from the upper peripheral edge 6d of the peripheral wall portion 9 as a base point. By forming the inclined surface 4b toward the trough 5c, as shown in FIGS. 12 to 14, the centrifugal force at the time of rotation is larger than that of the projection 6d projecting outward from the opening edge on the large-diameter mounting portion 3 side. can suppress expansion by the force, and also to reduce the inner diameter d ₃ of the nearest troughs 5c the large diameter mounting portion 3, valleys 5c is spaced further the height of the circumferential wall 9 from the large diameter mounting part 3 from being formed at a position, it is possible that the inner surface is less likely to touch the shaft during bending of the joint, to inhibit the expansion during the rotation by reducing the inside diameter d ₃ of the valley 5c.

  The resin boot according to the present invention as described above is manufactured by injection molding of a thermoplastic elastomer resin. The mold used for injection molding is, for example, as shown in FIG. 3, an openable / closable cavity mold 10 including split molds 10 </ b> A and 10 </ b> B and a core disposed between the split molds 10 </ b> A and 10 </ b> B of the cavity mold 10. A thermoplastic elastomer resin is injected and filled into a molding space 30 formed between the molds 20 and 20 formed between the molds 10 and 20, and the boot 1 is molded. The split molds 10A and 10B are fixed to a base plate (not shown) located on the back side of the split molds 10A and 10B, and are provided so as to be able to open and close together with the base plate. The core mold 20 has a base plate (not shown) on its upper side. ).

  As shown in FIGS. 4 and 5, the split dies 10A and 10B have substantially symmetrical shapes, and forming concave portions 30A and 30B constituting the outer peripheral surface of the molding space 30 are formed on the opposing split surfaces 11A and 11B. It is. The concave portions 30A and 30B are formed in a shape in which the small-diameter mounting portion 2 of the boot 1 is positioned below the dividing surfaces 11A and 11B and expands in a bellows shape upward. In order to form a dome-shaped lid from the opening end of the small-diameter mounting portion 2 of the boot 1 at the bottom of each recess 30A, 30B, approximately 1/4 spherical gate recesses 31A, 31B are formed. Yes, when the split dies 10A and 10B are closed, the outer peripheral surface of the dome-shaped gate is constituted by the pair of gate recesses 31A and 31B. A pair of grooves 41A forming a resin injection port 41 extending in the axial direction of the boot 1 molded in the molding space 30 (molded recesses 30A, 30B) downward from the lower end central portion of each of the gate recesses 31A, 31B, 41B is provided. The lower ends of the grooves 41A and 41B are grooves 42A and 42B that form a resin injection path 42 communicating with a nozzle mounting portion (reference numeral 43 in the split mold 10B) connected to a resin injection nozzle (not shown) of the injection molding machine. Communicate. It is preferable to provide the resin-filled dome-shaped gate 40 on the small-diameter mounting portion 2 side, since the distortion of the boot shape after molding becomes small.

  As shown in FIG. 5, the core mold 20 includes a hollow outer mold 20A that forms the inner peripheral surface of the molding space 30, and a substantially frustoconical middle mold 20B that is fitted in the outer mold 20A. It is fixed on the bottom with bolts. A dome-shaped convex portion 23 that forms the inner peripheral surface of the dome-shaped gate is formed at the lower end portion of the outer mold 20A, and the outer molds 20A and 20B of the core mold 20 are formed from the front end of the central portion of the dome-shaped convex portion 23. A vent hole 24 is formed so as to penetrate the substrate 20C. The lower end opening of the vent hole 24 opens to the dome-shaped gate 40 and is an air hole 21 through which air is ejected toward the inside of the molded product P. An opening / closing shaft 22 is provided in the vent hole 24 so as to be slidable instantaneously by a solenoid or the like. The opening / closing shaft 22 closes the air hole 21 so that the molten thermoplastic resin does not enter from the injection port 41 when the thermoplastic resin is injected, and the molds 10A and 10B of the cavity mold 10 are used when the molded product is removed. Simultaneously with the opening, the air hole 24 slides and rises, and high-pressure air from an air compressor or the like is blown from the air hole 21 toward the inner surface of the molded product, and the molded product is detached from the core mold 20.

  The shape of the dome-shaped gate 40 is not limited to the example shown in the figure, and the flow of the injected resin is not disturbed, and from the air hole 21 to the inside of the molded product, specifically, the dome-shaped gate 40 portion. As long as the high-pressure air blown toward the inner surface of the portion to be molded acts uniformly on the inner surface of the molded product, the longitudinal cross-sectional shape of the dome-shaped gate 40 is substantially hemispherical as shown in FIG. And the molten thermoplastic resin M is injected from the injection hole 41 provided at the apex portion of the substantially hemispherical gate 40, thereby disturbing the flow of the resin M (indicated by an arrow in the figure). Therefore, a molded product excellent in appearance and mechanical properties can be obtained without causing uneven flow and weld lines.

  Furthermore, the opening edge 40a to the molding space 30 in the dome-shaped gate 40 is formed in a cylindrical shape extending in parallel to the axial center of the boot 1 molded in the molding space 30, and the molten thermoplastic resin is formed in a dome shape. By injecting and filling the molding space 30 from the gate 40 toward the axial center of the boot molded in the molding space 30, the resin is injected linearly from the dome-shaped gate 40 into the molding space 30. The turbulent flow can be further effectively suppressed.

  Further, as shown in the figure, a vent hole 24 penetrating in the axial direction of the core mold 20 and connected to a high-pressure air supply means such as a compressor is provided in the core core portion 20, and the tip of the vent hole 24 is formed at the dome. An opening / closing shaft 22 that slides in the axial direction of the core mold 20 is provided in the ventilation hole 24 with the tip 22a facing the dome-shaped gate 40. By making the air hole 21 openable and closable, it is possible to reliably prevent the resin from entering the air hole 30 when the molten thermoplastic resin is injected into the molding space 30 and to form the core metal after molding. When the boot molded product P is released from the mold 20, the boot 1 molded from the core mold 20 is removed by blowing high-pressure air into the boot molded product P that is quickly molded simultaneously with the opening of the cavity mold 10. To do Come, it becomes possible to high productivity of the molding.

  Furthermore, as shown in FIG. 6, the diameter of the portion close to the tip of the vent hole 24 of the core mold 20 is reduced, and on the inner peripheral surface, one or a plurality of vent grooves extending in the axial direction, Four vent grooves 25 are provided, and as shown in FIG. 10, the opening / closing shaft 22 is retracted until the tip of the opening 22a comes to the position where the vent grooves 25 are provided to open the air holes 21 and the vent holes 24. By allowing high pressure air to be blown into the molded boot molded product P through the ventilation groove 25 and the air hole 21, the molten thermoplastic resin is injected into the molding space 30 into the air hole 21. Intrusion of resin can be reliably prevented.

  A procedure for injection-molding the resin boot of the present invention, for example, the constant velocity joint boot 1 from the thermoplastic elastomer, using the above-described injection mold will be described below. First, the core mold 20 is disposed in the cavity mold 10, and the divided molds 10A and 10B are joined together to form a molding space 30 corresponding to the boot shape (FIG. 3). Next, a molten thermoplastic resin is injected from the injection molding machine (not shown) connected to the nozzle mounting portion 43 into the molding space 30 through the resin injection path 42, the injection port 41, and the dome-shaped gate 40 of the mold. A boot molded product P with one end closed is formed by a portion c which is filled and formed on the dome-shaped gate 40 (FIGS. 7 and 8). After molding, when the split molds 10A and 10B are opened to the left and right (FIG. 10), when high-pressure air is blown against the inner surface of the portion c that becomes the lid of the molded product P that is externally fitted to the core mold 20, the core mold Pressure is uniformly applied to the inner surface of the molded product P that is in close contact with the mold 20 by the high-pressure air, and the molded product P is instantaneously expanded to be between the outer peripheral surface of the core mold 20 and the inner peripheral surface of the molded product P. At the same time as the gap is formed, the molded product P is extruded downward from the core mold 20 (FIG. 11).

  The molded product P removed from the core mold 20 is cut off from the portion c which became a lid at the time of molding shown in FIG. The product is a resin boot 1 as shown.

  The thermoplastic elastomer resin used in the production of the resin boot of the present invention is not particularly limited. For example, in the case of a boot for a constant velocity joint of an automobile, in addition to moldability, heat resistance, oil resistance, compression set An acrylic block copolymer having excellent properties and a low tensile permanent strain is preferred, and an olefin / acrylic composite thermoplastic elastomer resin is particularly preferred. Further, for example, thermoplastic polyurethane (TPU), chlorine-containing polymer, polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), chlorinated polyethylene (CPE), fluorine-containing polymer, polyvinylidene fluoride (PDVF), polyesters It is also possible to use thermoplastic polymers such as acrylonitrile-butadiene-styrene copolymer (ABS), styrene-acrylonitrile copolymer (SAN), styrene-maleic anhydride copolymer (SMA), polyacetals, polycarbonates, polyphenylene oxide and the like.

  As an acrylic block copolymer, what was described in Unexamined-Japanese-Patent No. 2004-300164 and Unexamined-Japanese-Patent No. 2004-315803 is mentioned, for example. As the olefin / acrylic composite thermoplastic elastomer resin, those containing (A) an acrylic block copolymer, (B) an olefinic thermoplastic elastomer, and further containing (C) a compatibilizer are suitable.

  A suitable olefin / acrylic composite thermoplastic elastomer resin is a thermoplastic elastomer composition comprising (A) an acrylic block copolymer and (B) an olefinic thermoplastic elastomer, and the above-mentioned (A), (B) In addition, a thermoplastic elastomer composition containing (C) a compatibilizing agent is more preferable.

The acrylic block copolymer (A) is preferably composed of an acrylic polymer block (a) and a methacrylic polymer block (b). The structure of the acrylic block copolymer (A) may be a linear block copolymer, a branched (star) block copolymer, or a mixture thereof, and can be used depending on processing characteristics and mechanical properties. However, a linear block copolymer is preferable in terms of cost and ease of polymerization. The structure of the linear block copolymer is such that the acrylic polymer block (a) and the methacrylic polymer block (b) are represented by the general formula: (ab) _n , general formula: b What is represented by-(ab) _n and general formula: (ab) _n- a (n is an integer of 1-3) is preferable. Among these, an ab type diblock copolymer, a bab type triblock copolymer, or a mixture thereof from the viewpoint of easy handling during processing and physical properties in the case of a composition. Is preferred.

  The acrylic block copolymer (A) preferably has a reactive functional group (c) in at least one of the blocks (a) and (b).

  Further, as the reactive functional group (c), the general formula (1):

(Wherein R ¹ is a hydrogen atom or a methyl group, which may be the same or different from each other, p is an integer of 0 or 1, q is an integer of 0 to 3), The unit (c) composed of the unit (c1) and / or the unit (c2) containing a carboxyl group is per polymer block of at least one of the acrylic polymer block (a) and the methacrylic polymer block (b). In the case where the number is 2 or more, the unit (c) may be polymerized by random copolymerization or block copolymerization. Good.

  When the structure of the block copolymer containing the unit (c) is shown as an example of a b-a-b type tri-block copolymer, (b / c) -ab type, (b / c) -a -(B / c) type, cb-a-b type, c-b-a-b-c type, b- (a / c) -b-type, b-a-c-b type, b- c-a-b type, and any of these may be used. Here, (a / c) means that the unit (c) is contained in the block (a), and (b / c) means that the unit (c) is contained in the block (b). C−a− and a−c− indicate that the unit (c) is bonded to the end of the block (a). In terms of expression, they are (a / c), (b / c), c-a-, a-c-, etc., all of which are acrylic polymer block (a) or methacrylic polymer block ( b).

  The number average molecular weight of the acrylic block copolymer (A) is preferably 30,000 to 500,000, more preferably 40000 to 400,000, and still more preferably 50,000 to 300,000. If the molecular weight is less than 30,000, sufficient mechanical properties as an elastomer may not be exhibited, and if it exceeds 500,000, processing properties may be deteriorated. The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferably 1 to 2, and more preferably 1 to 1.8. If Mw / Mn exceeds 2, the compression set of the acrylic block copolymer (A) may deteriorate. In addition, the said number average molecular weight (Mn) and a weight average molecular weight (Mw) calculated | required the molecular weight of polystyrene conversion using chloroform as a mobile phase using gel permeation chromatography.

  The composition ratio between the acrylic polymer block (a) and the methacrylic polymer block (b) is the required physical properties, the moldability required during processing of the composition, and the acrylic polymer block (a). What is necessary is just to determine from the molecular weight etc. which are each required for a methacrylic polymer block (b). When the range of the composition ratio of a preferable acrylic polymer block (a) and a methacrylic polymer block (b) is illustrated, the acrylic polymer block (a) is 50 to 90% by weight, and further 50 to 80% by weight. In particular, it is 50 to 70% by weight, and the methacrylic polymer block (b) is 50 to 10% by weight, further 50 to 20% by weight, particularly 50 to 30% by weight. When the proportion of the acrylic polymer block (a) is less than 50% by weight, the mechanical properties as an elastomer, particularly the elongation at break may be lowered, or the flexibility may be lowered. In some cases, rubber elasticity at high temperatures may be reduced.

The relationship between the glass transition temperature of the acrylic polymer block (a) and the methacrylic polymer block (b) is that the glass transition temperature of the acrylic polymer block (a) is Tg _a , and the methacrylic polymer block ( When b) is Tg _b , it is preferable to satisfy the following relationship.
Tg _a <Tg _b

The glass transition temperature (Tg) of the acrylic polymer block (a) and the methacrylic polymer block (b) is roughly in accordance with the following Fox formula, using the weight ratio of the monomer in each polymer block. Can be sought.
_{1 / Tg = (W 1 /} Tg 1) + (W 2 / Tg 2) + ... + (W m / Tg m)
W ₁ + W ₂ + ... + W _m = 1
(In the formula, Tg represents the glass transition temperature of the polymer block, and Tg ₁ , Tg ₂ ,..., Tg _m represent the glass transition temperatures of the polymerized monomers (homopolymers), and W ₁ , W ₂ ,..., W _m represent the weight ratio of the polymerized monomers.

  The glass transition temperature of each polymerized monomer in the Fox formula is described in, for example, Polymer Handbook Third Edition (Wiley-Interscience, 1989).

  The acrylic polymer block (a) contains 50 to 100% by weight, preferably 60 to 100% by weight of a unit containing an acrylate ester, and has a functional group serving as a precursor of the unit (c). 0 to 50% by weight, preferably 0 to 40% by weight of the monomer, and 0 to 50% by weight, and further 0 to 25% by weight of other vinyl monomers copolymerizable therewith. It is preferable to contain. If the proportion of the unit containing the acrylate ester is less than 50% by weight, the physical properties, particularly the elongation of the tensile properties, which are characteristics when using the acrylate ester may be reduced.

The molecular weight of the acrylic polymer block (a) may be determined from the required elastic modulus and rubber elasticity, the time required for the polymerization, and the like. When the number average molecular weight of the acrylic polymer block (a) is M _A , the range is exemplified. Preferably, M _A > 3000, more preferably M _A > 5000, still more preferably M _A > 10000, and particularly preferably M _A. > 20000, most preferably M _A > 40000. When the number average molecular weight M _{A of the} acrylic polymer block (a) is smaller than the above range, the tensile elongation becomes low. However, since the polymerization time tends to be longer when the number average molecular weight is large, the polymerization time may be set according to the required productivity, but is preferably 500,000 or less, more preferably 300,000 or less.

  Examples of the acrylic acid ester constituting the acrylic polymer block (a) include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, and acrylic acid. Acrylic aliphatic hydrocarbons such as n-hexyl, n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, stearyl acrylate, etc. ~ 18 alkyl) esters; acrylic acid cycloaliphatic hydrocarbon esters such as cyclohexyl acrylate and isobornyl acrylate; aromatic aromatic hydrocarbon esters such as phenyl acrylate and toluyl acrylate; aralkyl esters of acrylic acid such as benzyl acrylate Ester, ester of acrylic acid such as 2-methoxyethyl acrylate and 3-methoxybutyl acrylate and functional group-containing alcohol having etheric oxygen; trifluoromethyl methyl acrylate, 2-trifluoromethyl ethyl acrylate, acrylic 2-perfluoroethylethyl acid, 2-perfluoroethyl-2-perfluorobutylethyl acrylate, 2-perfluoroethyl acrylate, perfluoromethyl acrylate, diperfluoromethyl methyl acrylate, 2-peracrylate Fluorinated alkyl esters such as fluoromethyl-2-perfluoroethylmethyl, 2-perfluorohexylethyl acrylate, 2-perfluorodecylethyl acrylate, 2-perfluorohexadecylethyl acrylate, etc.These may be used alone or in combination of two or more. Among these acrylate esters, n-butyl acrylate is preferable from the viewpoint of low-temperature characteristics, compression set, cost, and availability. If oil resistance and mechanical properties are required, ethyl acrylate is preferred. When low temperature characteristics, mechanical characteristics, and compression set are required, 2-ethylhexyl acrylate is preferred. From the standpoints of mechanical properties, oil resistance and low temperature properties, 2-methoxyethyl acrylate 10-90% by weight, n-butyl acrylate 10-90% by weight, ethyl acrylate 0% in the whole acrylic polymer block (a) A mixture of ˜80 wt% is preferable, and a mixture of 2-methoxyethyl acrylate 15 to 85 wt%, n-butyl acrylate 15 to 85 wt%, and n-ethyl acrylate 0 to 70 wt% is more preferable.

  Examples of the functional group serving as a precursor of the unit (c) include t-butyl acrylate, isopropyl acrylate, α, α-dimethylbenzyl acrylate, α-methylbenzyl acrylate, and t-butyl methacrylate. , Isopropyl methacrylate, α, α-dimethylbenzyl methacrylate, α-methylbenzyl methacrylate, and the like, but are not limited thereto. The method for introducing the unit (c) into the acrylic block copolymer (A) will be described later.

  Further, examples of the vinyl monomer copolymerizable with the acrylate ester constituting the acrylic polymer block (a) include, for example, a methacrylic acid ester, an aromatic alkenyl compound, a vinyl cyanide compound, and a conjugated diene compound. , Halogenated unsaturated compounds, unsaturated dicarboxylic acid compounds, vinyl ester compounds, maleimide compounds, and the like.

  Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, and n-methacrylate. Methacrylic acid aliphatic carbonization such as hexyl, n-heptyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate, stearyl methacrylate Hydrogen (for example, alkyl having 1 to 18 carbon atoms) ester; methacrylic acid alicyclic hydrocarbon ester such as cyclohexyl methacrylate and isobornyl methacrylate; aralkyl methacrylic acid aralkyl ester such as benzyl methacrylate; phenyl methacrylate Methacrylic acid aromatic hydrocarbon esters such as toluyl methacrylate; Esters of methacrylic acid such as 2-methoxyethyl methacrylate and 3-methoxybutyl methacrylate and functional group-containing alcohols having etheric oxygen; Trifluoromethyl methyl acrylate, 2-trifluoromethyl ethyl methacrylate, 2-perfluoroethyl ethyl methacrylate, 2-perfluoroethyl-2-perfluorobutyl ethyl methacrylate, 2-perfluoro methacrylate Ethyl, perfluoromethyl methacrylate, diperfluoromethyl methyl methacrylate, 2-perfluoromethyl-2-perfluoroethyl methyl methacrylate, 2-perfluorohexyl methacrylate, 2-par methacrylate Fluoro Shiruechiru, such as methacrylic acid fluorinated alkyl esters such as meta 2-perfluoro-hexadecyl acrylate and the like.

  Examples of the aromatic alkenyl compound include styrene, α-methylstyrene, p-methylstyrene, and p-methoxystyrene.

  Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

  Examples of the conjugated diene compound include butadiene and isoprene.

  Examples of the halogen-containing unsaturated compound include vinyl chloride, vinylidene chloride, perfluoroethylene, perfluoropropylene, and vinylidene fluoride.

  Examples of the unsaturated dicarboxylic acid compound include maleic anhydride, maleic acid, monoalkyl esters and dialkyl esters of maleic acid, fumaric acid, monoalkyl esters and dialkyl esters of fumaric acid, and the like.

  Examples of the vinyl ester compound include vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate.

  Examples of the maleimide compound include maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, cyclohexylmaleimide and the like.

  The copolymerizable vinyl monomers may be used alone or in combination of two or more. The vinyl monomer is required when the acrylic block copolymer (A) is used as a composition, and the glass transition temperature, elastic modulus and polarity required for the acrylic polymer block (a). The preferred one can be selected according to the physical properties to be used, compatibility with the olefinic thermoplastic elastomer (B) and the polyorganosiloxane graft polymer (D), and the like. For example, acrylonitrile can be copolymerized for the purpose of improving oil resistance.

The glass transition temperature of the acrylic polymer block (a) is preferably 50 ° C. or lower, more preferably 0 ° C. or lower. When the glass transition temperature is higher than 50 ° C., the rubber elasticity of the acrylic block copolymer (A) may be lowered. Setting the glass transition temperature of the acrylic polymer block _(a) (Tg a) uses the values described in Polymer Handbook Third Edition of the foregoing as the glass transition temperature of the homopolymer of each monomer constituting the polymer block From the polymerization ratio of each monomer, the weight ratio of the monomer constituting the polymer block can be adjusted according to the Fox formula.

  The methacrylic polymer block (b) is a methacrylic polymer block (b) as a whole from the viewpoint of easily obtaining an acrylic block copolymer (A) having desired physical properties, cost and availability. Among them, a monomer containing a methacrylic acid ester is contained in an amount of 50 to 100% by weight, preferably 50 to 85% by weight, and a monomer having a functional group serving as a precursor of the unit (c). Containing 0.1 to 50% by weight, preferably 0.1 to 25% by weight of another vinyl monomer copolymerizable therewith, preferably 20 to 99.5% by weight Is preferred.

The molecular weight of the methacrylic polymer block (b) may be determined from the required cohesive force and the time required for the polymerization. The cohesive force is said to depend on the interaction between molecules (in other words, polarity) and the degree of entanglement, and as the number average molecular weight increases, the entanglement point increases and the cohesive force increases. That is, the number-average molecular weight required for the methacrylic polymer block (b) and M _B, the the entanglement molecular weight of the polymer constituting the methacrylic polymer block (b) of M _B as Mc _B Exemplifying the range, when cohesive force is required, preferably M _B > Mc _B. As a further example, when a further cohesive force is required, preferably M _B > 2 × Mc _B. Conversely, when it is desired to achieve both a certain cohesive force and creep property, Mc _B <M _B <2 × Mc _B is preferred. The molecular weight between the entanglement points may be referred to Wu et al. (Polym. Eng. And Sci., 1990, Vol. 30, p. 753). For example, the range of the number average molecular weight of the methacrylic polymer block (b) when the cohesive force is required assuming that the methacrylic polymer block (b) is entirely composed of methyl methacrylate. Then, it is preferable that it is 9200 or more. However, when the unit (c) is contained in the methacrylic polymer block (b), the cohesive force by the unit (c) is imparted, so the number average molecular weight can be set lower than this. When the number average molecular weight is increased, the polymerization time tends to be longer, so it may be set according to the required productivity, but is preferably 200000 or less, more preferably 100000 or less.

  Examples of the methacrylic acid ester constituting the methacrylic polymer block (b) include those exemplified as vinyl monomers copolymerizable with the acrylate ester constituting the acrylic polymer block (a). It is done. These methacrylic acid esters may be used alone or in combination of two or more. Among these, methyl methacrylate is preferable from the viewpoints of cost and availability.

  Examples of the monomer having a functional group serving as a precursor of the unit (c) include monomers similar to the constituent monomers exemplified in the description of the acrylic polymer block (a).

  Examples of vinyl monomers copolymerizable with the methacrylic acid ester constituting the methacrylic polymer block (b) include acrylic acid esters, aromatic alkenyl compounds, vinyl cyanide compounds, conjugated diene compounds, halogens. Examples thereof include an unsaturated compound, an unsaturated dicarboxylic acid compound, a vinyl ester compound, and a maleimide compound. As the copolymerizable vinyl monomer, at least one of the above constituent monomers is used.

  As said acrylic ester, the monomer similar to the structural monomer illustrated by description of the said acrylic polymer block (a) is mentioned.

  The aromatic alkenyl compound, vinyl cyanide compound, conjugated diene compound, halogen-containing unsaturated compound, unsaturated dicarboxylic acid compound, vinyl ester compound and maleimide compound are the same in the description of the acrylic polymer block (a). Examples thereof include the same monomers as the constituent monomers exemplified as the polymerizable vinyl monomer.

  The polymer of methyl methacrylate is almost quantitatively depolymerized by thermal decomposition, but in order to suppress this, when the methacrylic polymer block (b) is composed of a polymer of methyl methacrylate polymer. Can be copolymerized with acrylate esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-methoxyethyl acrylate or mixtures thereof or styrene. Furthermore, acrylonitrile can be copolymerized with the methacrylic polymer block (b) for the purpose of improving oil resistance.

The glass transition temperature (Tg _b ) of the methacrylic polymer block (b) is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. When the glass transition temperature is less than 100 ° C., rubber elasticity at a high temperature may be lowered from a desired value. The glass transition temperature (Tg _b ) of the methacrylic polymer block (b) is set by the value described in the above-mentioned Polymer Handbook 3rd edition as the glass transition temperature of the homopolymer of each monomer constituting the polymer block. It can be carried out by adjusting the weight ratio of the monomer constituting the polymer block according to the Fox formula from the polymerization ratio of each monomer.

  The reactive functional group (unit (c)) in the acrylic polymer block (a) and / or the methacrylic polymer block (b) has reactivity with a compound having an amino group, a hydroxyl group, an epoxy group, or the like. Thus, the acrylic block copolymer (A) can be used as a crosslinking site with the compatibilizer (C) when blended with the thermoplastic elastomer (B). Moreover, since the unit (c) has a high glass transition temperature (Tg), when introduced into the methacrylic polymer block (b), which is a hard segment, the heat resistance of the acrylic block copolymer (A). Can be improved. The glass transition temperature of the polymer containing the unit (c) is, for example, as high as 159 ° C. in the case of polymethacrylic anhydride, and by introducing the unit (c), the acrylic block copolymer (A) Heat resistance can be improved, which is preferable.

  The unit (c) is represented by the general formula (1):

(Wherein R ¹ is a hydrogen atom or a methyl group, which may be the same or different from each other, p is an integer of 0 or 1, q is an integer of 0 to 3), It consists of a unit (c1) and a unit (c2) containing a carboxyl group.
Q in the general formula (1) is an integer of 0 to 3, preferably 0 or 1, and more preferably 1. When q exceeds 3, polymerization may become complicated or cyclization to an acid anhydride group may be difficult.
In general formula (1), p is an integer of 0 or 1. When q is 0, p is also 0. When q is 1 to 3, p is preferably 1.

The unit (c) is contained in the acrylic polymer block (a) and / or the methacrylic polymer block (b). The introduction site of the unit (c) is required for the reaction point of the acrylic block copolymer (A), the cohesive force and the glass transition temperature of the block constituting the acrylic block copolymer (A), and further. Depending on the physical properties of the acrylic block copolymer (A), it can be used properly. From the viewpoint of improving the heat resistance and heat decomposability of the acrylic block copolymer (A), the unit (c) may be introduced into the methacrylic polymer block (b). From the viewpoint of imparting rubber elasticity to the coalescence (A), the unit (c) may be introduced into the acrylic polymer block (a) as a crosslinkable reaction site (crosslinking point). From the viewpoint of control of the reaction point, heat resistance, rubber elasticity, etc., it is preferable to have the unit (c) in either the acrylic polymer block (a) or the methacrylic polymer block (b). When the unit (c) is contained in the methacrylic polymer block (b), R ^{1 in the} general formula (1) is preferably a methyl group, and is contained in the acrylic polymer block (a). In this case, R ¹ in the general formula (1) is preferably a hydrogen atom. When R ¹ is a hydrogen atom when the unit (c) is contained in the methacrylic polymer block (b), or when R ¹ is a methyl group when contained in the acrylic polymer block (a) The difference in glass transition temperature between the acrylic polymer block (a) and the methacrylic polymer block (b) is reduced, and the rubber elasticity of the acrylic block copolymer (A) tends to be lowered.

  The preferred range of the content of the unit (c) is the cohesive strength of the unit (c), the reactivity with the compatibilizer (C), the structure and composition of the acrylic block copolymer (A), the acrylic block copolymer It varies depending on the number of blocks constituting the coalescence (A), the glass transition temperature, and the site and manner in which the acid anhydride group-containing unit (c1) and carboxyl group-containing unit (c2) are contained. 0.1-99.9 weight% is preferable in the whole acrylic block copolymer (A), 0.1-80 weight% is more preferable, 0.1-50 weight% is still more preferable. When the content of the unit (c) is less than 0.1% by weight, the compatibility between the acrylic block copolymer (A) and the compatibilizer (C) may be insufficient. Further, when the unit (c) having a high Tg is introduced into the methacrylic polymer block (b), which is a hard segment, for the purpose of improving the heat resistance of the methacrylic polymer block (b), 0.1% by weight. If it is less, the improvement in heat resistance is insufficient and the expression of rubber elasticity at high temperatures may be reduced. On the other hand, if it exceeds 99.9% by weight, the cohesive force becomes too strong and the productivity may be lowered.

  When the acrylic block copolymer (A) contains a unit (c2) containing a carboxyl group, heat resistance and cohesive force are improved. The unit (c2) containing a carboxyl group has a strong cohesive force, and the polymer of a monomer containing a carboxyl group has a high glass transition temperature (Tg). For example, the glass transition temperature (Tg) of polymethacrylic acid is As high as 228 ° C., the heat resistance of the block copolymer is improved. A functional group such as a hydroxyl group also has hydrogen bonding ability, but has a lower Tg and a smaller effect of improving heat resistance than the unit (c2) containing a carboxyl group. Therefore, if it contains the unit (c2) containing a carboxyl group, the heat resistance and cohesion of the acrylic block copolymer (A) can be further improved, which is preferable.

  The content of the carboxyl group-containing unit (c2) can be 1 or 2 or more per polymer block. When the number is 2 or more, the unit (c2) is The mode of polymerization may be random copolymerization or block copolymerization.

  The preferred range of the content of the carboxyl group-containing unit (c2) is the cohesive strength of the carboxyl group-containing unit (c2), the structure and composition of the block copolymer, the number of blocks constituting the block copolymer, In addition, it varies depending on the site and mode of the unit (c2) containing a carboxyl group.

  The content of the carboxyl group-containing unit (c2) is preferably from 0.1 to 50% by weight, more preferably from 0.5 to 50% by weight, and more preferably from 1 to 40% by weight in the entire acrylic block copolymer (A). % Is more preferable. If the amount exceeds 50% by weight, the carboxyl group-containing unit (c2) tends to cyclize with the adjacent ester unit at high temperature, so that the physical properties after molding change, and stable physical properties are obtained. It may be difficult to make a product. In addition, when producing | generating the unit (c2) containing a carboxyl group in the introduction process of a unit (c), 0.1 weight% or more is normally produced | generated. When the production amount is less than 0.1% by weight, the heat resistance and cohesion can be improved even if the carboxyl group-containing unit (c2) is introduced into the methacrylic polymer block (b) which is a hard segment. It may be insufficient.

  Although it does not specifically limit as a manufacturing method of an acryl-type block copolymer (A), It is preferable to use controlled polymerization. Examples of the controlled polymerization include living anion polymerization, radical polymerization using a chain transfer agent, and recently developed living radical polymerization. Living radical polymerization is preferable from the viewpoint of controlling the molecular weight and structure of the block copolymer and copolymerizing a monomer having a crosslinkable functional group. Furthermore, atom transfer radical polymerization is preferable from the viewpoint of ease of control.

  In the atom transfer radical polymerization, an organic halide or a sulfonyl halide compound is used as an initiator, and a metal complex having a group metal of group 8, 9, 10, or 11 as a central metal in the periodic table is used as a catalyst ( For example, Matyjaszewski et al., Journal of American Chemical Society, 1995, 117, 5614, Macromolecules, 1995, 28, 7901, Science, 1996, 272, 866, or Sawamoto et al., 28, 17).

  According to these methods, in general, the polymerization rate is very high, and the radical polymerization is likely to cause a termination reaction such as coupling between radicals, but the polymerization proceeds in a living manner and Mw / Mn = 1 having a narrow molecular weight distribution. A polymer having a molecular weight of about 1 to 1.5 is obtained, and the molecular weight can be freely controlled by the ratio of the monomer and the initiator when charged.

  In the atom transfer radical polymerization method, as the organic halide or sulfonyl halide compound used as an initiator, a monofunctional, difunctional, or polyfunctional compound can be used. These can be used properly according to the purpose. When producing a diblock copolymer, a monofunctional compound is preferable. In the case of producing an aba type triblock copolymer or a babb type triblock copolymer, it is preferable to use a bifunctional compound. In the case of producing a branched block copolymer, it is preferable to use a polyfunctional compound.

Examples of the monofunctional compound include compounds represented by the following chemical formulas.
C ₆ H ₅ —CH ₂ X
C ₆ H ₅ -CHX-CH _{3
C 6 H 5 -C (CH 3} ) 2 X
R ¹ —CHX—COOR ^{2
_{R 1 -C (CH 3) X}} -COOR 2
R ¹ —CHX—CO—R ²
R ¹ —C (CH ₃ ) X—CO—R ²
R ¹ —C ₆ H ₄ —SO ₂ X
(In the formula, C ₆ H ₄ represents a phenylene group. The phenylene group may be ortho-substituted, meta-substituted, or para-substituted. R ¹ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and 6 to 6 carbon atoms. 20 represents an aryl group or an aralkyl group having 7 to 20 carbon atoms, X represents chlorine, bromine or iodine, and R ² represents a monovalent organic group having 1 to 20 carbon atoms.)

Examples of the bifunctional compound include compounds represented by the following chemical formulas.
X—CH ₂ —C ₆ H ₄ —CH ₂ —X
_{X-CH (CH 3) -C} 6 H 4 -CH (CH 3) -X
_{X-C (CH 3) 2} -C 6 H 4 -C (CH 3) 2 -X
X—CH (COOR ³ ) — (CH ₂ ) _n —CH (COOR ³ ) —X
_{X-C (CH 3) (} COOR 3) - (CH 2) n -C (CH 3) (COOR 3) -X
X—CH (COR ³ ) — (CH ₂ ) _n —CH (COR ³ ) —X
_{X-C (CH 3) (} COR 3) - (CH 2) n -C (CH 3) (COR 3) -X
_{X-CH 2 -CO-CH 2} -X
_{X-CH (CH 3) -CO} -CH (CH 3) -X
_{X-C (CH 3) 2} -CO-C (CH 3) 2 X
_{X-CH (C 6 H 5} ) -CO-CH (C 6 H 5) -X
X—CH ₂ —COO— (CH ₂ ) _n —OCO—CH ₂ —X
_{X-CH (CH 3) -COO-} (CH 2) n -OCO-CH (CH 3) -X
_{X-C (CH 3) 2} -COO- (CH 2) n -OCO-C (CH 3) 2 -X
_{X-CH 2 -CO-CO-} CH 2 -X
_{X-CH (CH 3) -CO} -CO-CH (CH 3) -X
_{X-C (CH 3) 2} -CO-CO-C (CH 3) 2 -X
X—CH ₂ —COO—C ₆ H ₄ —OCO—CH ₂ —X
_{X-CH (CH 3) -COO} -C 6 H 4 -OCO-CH (CH 3) -X
_{X-C (CH 3) 2} -COO-C 6 H 4 -OCO-C (CH 3) 2 -X
_{X-SO 2 -C 6 H 4} -SO 2 -X
(In the formula, R ³ represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. C ₆ H ₄ represents a phenylene group. The phenylene group is ortho-substituted. C ₆ H ₅ represents a phenyl group, n represents an integer of 0 to 20, and X represents chlorine, bromine or iodine.

Examples of the polyfunctional compound include compounds represented by the following chemical formulas.
C ₆ H ₃ (CH ₂ X) _{3
C 6 H 3 (CH (CH} 3) -X) 3
_{C 6 H 3 (C (CH} 3) 2 -X) 3
_{C 6 H 3 (OCO-CH} 2 X) 3
_{C 6 H 3 (OCO-CH} (CH 3) -X) 3
_{C 6 H 3 (OCO-C} (CH 3) 2 -X) 3
C ₆ H ₃ (SO ₂ X) ₃
(In the formula, C ₆ H ₃ represents a trisubstituted phenyl group. The position of the substituent of the trisubstituted phenyl group may be any of the 1st to 6th positions. X represents chlorine, bromine or iodine.)

  In these organic halides or sulfonyl halide compounds that can be used as initiators, the carbon to which the halogen is bonded is bonded to the carbonyl group, phenyl group, etc., and the carbon-halogen bond is activated to initiate polymerization. To do. The amount of the initiator to be used may be determined from the ratio with the monomer in accordance with the required molecular weight of the block copolymer. That is, the molecular weight of the block copolymer can be controlled by the number of monomers used per molecule of the initiator.

  The transition metal complex used as the catalyst for the atom transfer radical polymerization is not particularly limited, but as a preferred one, a complex of monovalent and zerovalent copper, divalent ruthenium, divalent iron or divalent nickel is preferable. Can be mentioned. Among these, a copper complex is preferable from the viewpoint of cost and reaction control.

Examples of the monovalent copper compound include cuprous chloride, cuprous bromide, cuprous iodide, cuprous cyanide, cuprous oxide, cuprous perchlorate and the like. . In the case of using a copper compound, 2,2′-bipyridyl and its derivative, 1,10-phenanthroline and its derivative, tetramethylethylenediamine (TMEDA), pentamethyldiethylenetriamine, hexamethyl (2-aminoethyl) Polyamines such as amines can also be added as ligands. A tristriphenylphosphine complex of divalent ruthenium chloride (RuCl ₂ (PPh ₃ ) ₃ ) can also be used as a catalyst.

When a ruthenium compound is used as a catalyst, aluminum alkoxides can also be added as an activator. Further, a divalent iron bistriphenylphosphine complex (FeCl ₂ (PPh ₃ ) ₂ ), a divalent nickel bistriphenylphosphine complex (NiCl ₂ (PPh ₃ ) ₂ ), and a divalent nickel bistributylphosphine A complex (NiBr ₂ (PBu ₃ ) ₂ ) can also be used as a catalyst. The amount of the catalyst, ligand and activator used is not particularly limited, but can be appropriately determined from the relationship between the amount of initiator, monomer and solvent used and the required reaction rate.

  The atom transfer radical polymerization can be carried out without solvent (bulk polymerization) or in various solvents. Examples of the solvent include hydrocarbon solvents such as benzene and toluene, halogenated hydrocarbon solvents such as methylene chloride and chloroform, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, methanol, ethanol, propanol, and isopropanol. Alcohol solvents such as n-butanol and t-butanol, nitrile solvents such as acetonitrile, propionitrile, benzonitrile, ester solvents such as ethyl acetate and butyl acetate, carbonate solvents such as ethylene carbonate and propylene carbonate, etc. These can be used by mixing at least one of them. Moreover, when using a solvent, the usage-amount can be suitably determined from the relationship between the viscosity of the whole system, and the required reaction rate (namely, stirring efficiency).

  The atom transfer radical polymerization can be performed preferably in the range of room temperature to 200 ° C, more preferably 50 to 150 ° C. If the atom transfer radical polymerization temperature is lower than room temperature, the viscosity may be too high and the reaction rate may be slow, and if it exceeds 200 ° C., an inexpensive polymerization solvent may not be used.

  As a method for producing the acrylic block copolymer (A) by the atom transfer radical polymerization, a method of sequentially adding monomers, a method of polymerizing the next block using a polymer synthesized in advance as a polymer initiator And a method of bonding separately polymerized polymers by reaction. These methods can be used properly according to the purpose. From the viewpoint of simplicity of the production process, a method by sequential addition of monomers is preferred.

  Furthermore, a method for introducing a unit (c) comprising an acid anhydride group-containing unit (c1) and / or a carboxyl group-containing unit (c2) into the acrylic block copolymer (A) will be described below. .

  The method for introducing the acid anhydride group-containing unit (c1) is not particularly limited, but a unit containing a group that serves as a precursor of the acid anhydride group is introduced into the block copolymer, and then the ring. It is preferable to make it. Details of the method will be described below.

  General formula (2):

(Wherein R ² represents a hydrogen atom or a methyl group, R ³ represents a hydrogen atom, a methyl group or a phenyl group, and may be the same as or different from each other except that it contains at least one methyl group). A block copolymer composition using the monomer exemplified below as a block copolymer having at least one unit, that is, an acrylic ester constituting the acrylic polymer block (a), preferably 180 to 300 It can be introduced by melt-kneading and cyclization at a temperature of ° C. When the temperature is lower than 180 ° C., the acid anhydride group may be insufficiently formed. When the temperature is higher than 300 ° C., the monomers exemplified below as the acrylic acid ester constituting the acrylic polymer block (a) are used. The used acrylic block copolymer itself may be decomposed.

  The unit represented by the general formula (2) is eliminated and cyclized with an adjacent ester unit at a high temperature to generate, for example, a 6-membered cyclic acid anhydride group (for example, Hatada et al., J.M. Chemistry (JMS PURE APPL. CHEM.), A30 (9 & 10), PP.645-667 (1993)). According to these, in general, a polymer having a bulky ester unit and having β-hydrogen is decomposed at a high temperature to produce a carboxyl group, followed by cyclization, such as a 6-membered ring. An acid anhydride group is formed. By using these methods, an acid anhydride group can be easily introduced into the acrylic block copolymer (A). Specific examples of the monomer constituting the unit represented by the general formula (2) include t-butyl acrylate, isopropyl acrylate, α, α-dimethylbenzyl acrylate, α-methylbenzyl acrylate, meta Examples include, but are not limited to, t-butyl acrylate, isopropyl methacrylate, α, α-dimethylbenzyl methacrylate, and α-methylbenzyl methacrylate. Among these, t-butyl acrylate and t-butyl methacrylate are preferable from the viewpoint of availability, ease of polymerization, and ease of formation of acid anhydride groups.

  Various methods can be applied to the introduction of the carboxyl group-containing unit (c2), and there is no particular limitation. However, in the process of introducing the acid anhydride group-containing unit (c1) into the acrylic block copolymer. It is preferable to generate a unit (c2) containing a carboxyl group by appropriately adjusting the heating temperature and time according to the type and content of the unit represented by the general formula (2). This is because it is easy to control the reaction point of the acrylic block copolymer (B) and to introduce the carboxyl group-containing unit (c2) into the acrylic block copolymer (A).

  Therefore, from the viewpoint of the introduction method, the carboxyl group-containing unit (c2) is preferably contained in the same block as the block containing the acid anhydride group-containing unit (c1). From the point of cohesive strength, it is more preferable that it is contained in the methacrylic polymer block (b). That is, by introducing a unit (c2) having a carboxyl group with high Tg and cohesive force into the methacrylic polymer block (b) which is a hard segment, it becomes possible to express rubber elasticity more at high temperatures. It is. On the other hand, when the acrylic polymer block (a) contains a unit (c2) having a carboxyl group, it is preferable from the viewpoint of compatibility with the compatibilizing agent (C).

  Next, (B) the olefinic thermoplastic elastomer in the thermoplastic elastomer composition will be described. The olefinic thermoplastic elastomer (B) is not particularly limited, but is a polyolefin composed of a thermoplastic polyolefin homopolymer or copolymer, and an olefinic rubber or acrylonitrile butadiene that is completely crosslinked or partially crosslinked. What consists of a combination with rubber | gum (NBR) can be used preferably.

  The polyolefins include thermoplastic and crystalline polyolefin homopolymers and copolymers. Among these, those containing polypropylene as a main component are preferable, and a copolymer containing ethylene in polypropylene is more preferable in order to improve low temperature characteristics.

  As the olefin rubber, ethylene / propylene rubber having excellent low temperature characteristics and EPDM rubber which is a terpolymer of non-conjugated diene are preferable, and those obtained by dynamically crosslinking EPDM rubber in an olefin resin are particularly preferable. Since EPDM rubber can be uniformly dispersed in a small amount of olefin resin by dynamically cross-linking EPDM rubber in olefin resin, it has excellent rubber properties such as compression durability strain while having thermoplasticity. Can be expressed.

  Moreover, as an olefin type thermoplastic elastomer (B), it is preferable to use a 23-degree C Shore A hardness of 50-90, especially 65-85. Such olefin-based thermoplastic elastomers are commercially available under trade names such as Santoprene and GEOLLAST (both manufactured by Advanced Elastomers), and can be easily obtained from the market.

  Furthermore, the compatibilizing agent (C) in the thermoplastic elastomer composition is not particularly limited, but in order to better compatibilize the acrylic block copolymer (A) and the olefinic thermoplastic elastomer (B), An olefinic thermoplastic resin (modified polyolefin) containing an epoxy group that reacts with the unit (c) such as polymethacrylic anhydride of the acrylic block copolymer (A) is preferred. Examples thereof include commercially available copolymers of ethylene and glycidyl methacrylate, or ethylene and glycidyl methacrylate having methyl acrylate, polypropylene grafted with glycidyl methacrylate, and the like. The content of glycidyl methacrylate in these modified polyolefin resins is preferably 0.05 wt% to 50 wt%, more preferably 0.1 wt% to 20 wt%. If the glycidyl methacrylate content is less than 0.05% by weight, the compatibility between the acrylic block copolymer (A) and the olefinic thermoplastic elastomer (B) may be insufficient, and the tensile strength may deteriorate. . When the content of glycidyl methacrylate is more than 50% by weight, the cohesiveness of the acrylic block copolymer (A) and the olefinic thermoplastic elastomer (B) becomes too strong, and the tensile elongation may be lowered. These modified polyolefin resins are, for example, commercially available product names such as Bond First (manufactured by Sumitomo Chemical Co., Ltd.), Modiper (manufactured by Nippon Oil & Fats Co., Ltd.), and can be easily obtained from the market.

  The thermoplastic elastomer composition used in the present invention includes (A) an acrylic block copolymer and (B) an olefin thermoplastic elastomer, and in addition to (A) and (B) (C ) Containing a compatibilizing agent is suitable. For example, 50 to 600 parts by weight of the olefinic thermoplastic elastomer (B), more preferably 200 to 100 parts by weight with respect to 100 parts by weight of the acrylic block copolymer (A). It is preferable that it consists of 600 parts by weight, more preferably 400 parts by weight, and (C) 5 to 50 parts by weight of a compatibilizer. When the respective contents are within the above ranges, a molded article having good heat resistance, oil resistance, and injection molding can be obtained, which is particularly preferable in the case of a boot for a constant velocity joint for automobiles.

This thermoplastic elastomer composition measures the acrylic block copolymer (A), olefinic thermoplastic elastomer (B), and compatibilizer (C) before being actually molded and put them into a molding machine. However, from the viewpoint of handling, uniformity of kneading, etc., it is preferable to pelletize before molding.
Below, the pelletization is demonstrated.

  The method for pelletizing the thermoplastic elastomer composition is not particularly limited, but mechanically while heating at an appropriate temperature using a known apparatus such as a Banbury mixer, roll mill, kneader, single-screw or multi-screw extruder. Can be shaped into pellets. What is necessary is just to adjust the temperature at the time of kneading | mixing according to the melting temperature of the acrylic block copolymer (A), olefin type thermoplastic elastomer (B), and compatibilizer (C) to be used, for example, 180-300 degreeC. It can be pelletized by melt kneading.

  Moreover, when the low temperature characteristic is requested | required as a thermoplastic elastomer resin used for this invention, it is a composition which consists of an acrylic type block copolymer (A) and a polyorganosiloxane type graft polymer (D). Is preferred. Further, when a high modulus of elasticity is required, a composition comprising an acrylic block copolymer, a polyorganosiloxane graft polymer (D), a thermoplastic resin, a lubricant and an inorganic filler is preferable.

  The composition of the polyorganosiloxane-based graft polymer (D) in the thermoplastic elastomer resin is not particularly limited, but the monomer (d2) is present in the presence of 40 to 95% by weight of the polyorganosiloxane (d1). ) Is polymerized in an amount of 0 to 10% by weight, and a vinyl monomer (d3) is polymerized in an amount of 5 to 60% by weight [100% by weight in total of (d1), (d2) and (d3)] It is preferably a coalescence. The monomer (d2) is composed of 50 to 100% by weight of a polyfunctional monomer (x) containing two or more polymerizable unsaturated bonds in the molecule, and other copolymerizable vinyl monomers ( y) A monomer composed of 0 to 50% by weight. Furthermore, it is preferable that the content of the graft component combining the monomer (d2) and the vinyl monomer (d3) is 5 to 40% by weight and the polyorganosiloxane content is 95 to 60% by weight.

  The thermoplastic elastomer resin can be blended with a lubricant, an inorganic filler, and a thermoplastic resin in order to increase the elastic modulus at a high temperature. Regarding the blending amount, the polyorganosiloxane graft polymer (D) 10 to 100 parts by weight, the lubricant 0.1 to 10 parts by weight, and the inorganic filler 0 to 100 parts by weight of the acrylic block copolymer (A). 0.1 to 100 parts by weight and 0.1 to 100 parts by weight of a thermoplastic resin can be exemplified as preferable ranges.

  Examples of the lubricant include fatty acids such as stearic acid and palmitic acid, fatty acid metal salts such as calcium stearate, zinc stearate, magnesium stearate, potassium palmitate and sodium palmitate, polyethylene wax, polypropylene wax, and montanic acid wax. Waxes, low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene, polyorganosiloxanes such as dimethylpolysiloxane, octadecylamine, alkyl phosphates, fatty acid esters, amide-based lubricants such as ethylene bisstearamide, 4-fluoro Examples thereof include, but are not limited to, fluorine resin powders such as fluorinated ethylene resin, molybdenum disulfide powder, silicone resin powder, silicone rubber powder, and silica. These may be used alone or in combination of two or more. Of these, stearic acid, zinc stearate, calcium stearate, magnesium stearate, and stearyl amide are preferred from the viewpoint of low friction and processability on the resin surface.

  Inorganic fillers include, for example, titanium oxide, zinc sulfide, zinc oxide, carbon black, calcium carbonate, calcium silicate, clay, kaolin, silica, mica powder, alumina, glass fiber, metal fiber, potassium titanate whisker, asbestos , Wollastonite, mica, talc, glass flake, milled fiber, metal powder, and the like, but are not limited thereto. These may be used alone or in combination. Of these, silica is preferable from the viewpoint of high elastic modulus, and carbon black and titanium oxide are preferable from the viewpoint of weather resistance and use as a pigment.

  Examples of the thermoplastic resin include polyvinyl chloride resin, polyethylene resin, polypropylene resin, cyclic olefin copolymer resin, polymethyl methacrylate resin, polystyrene resin, polyphenylene ether resin, polycarbonate resin, polyester resin, Examples thereof include polyamide resins, polyacetal resins, polyphenylene sulfide resins, polysulfone resins, polyimide resins, polyetherimide resins, polyetherketone resins, polyetheretherketone resins, polyamideimide resins, and imidized polymethylmethacrylate resins. These may be used alone or in combination of two or more. Among these, those having good compatibility with the acrylic block copolymer (A) are preferably used, and those having a functional group capable of reacting with an acid anhydride group are more preferably used. Examples of the functional group capable of reacting with the acid anhydride group include an amino group and a hydroxyl group, and examples of the thermoplastic resin having these include a polyester resin and a polyamide resin. Thermoplastic resins containing functional groups that react with acid anhydride groups other than these can also be suitably used.

  The thermoplastic elastomer resin used in the present invention has a stabilizer (anti-aging agent, light stabilizer, UV absorber, etc.), flexibility imparting agent, flame retardant, release agent, antistatic depending on the required properties. Agents, antibacterial and antifungal agents may be added. These additives may be appropriately selected and used according to the required physical properties, workability, and the like.

  Examples of the stabilizer (anti-aging agent, light stabilizer, ultraviolet absorber, etc.) include, but are not limited to, the following compounds.

  Anti-aging agents include phenyl α-naphthylamine (PAN), octyldiphenylamine, N, N′-diphenyl-p-phenylenediamine (DPPD), N, N′-di-β-naphthyl-p-phenylenediamine (DNPD). N- (1,3-dimethyl-butyl) -N′-phenyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine (IPPN), N, N′-diallyl-p-phenylene Diamine, phenothiazine derivative, diallyl-p-phenylenediamine mixture, alkylated phenylenediamine, 4,4'-α, α-dimethylbenzyldiphenylamine, p, p-toluenesulfonylaminodiphenylamine, N-phenyl-N '-(3- Methacryloyloxy-2-hydropropyl) -p-pheny Diamines, diallylphenylenediamine mixtures, diallyl-p-phenylenediamine mixtures, N- (1-methylheptyl) -N-phenyl-p-phenylenediamine, amine-based antioxidants such as diphenylamine derivatives, 2-mercaptobenzimidazole (MBI) ) Imidazole anti-aging agents, phenolic anti-aging agents such as 2,6-di-t-butyl-4-methylphenol, phosphate anti-aging agents such as nickel diethyl-dithiocarbamate, triphenyl phosphite Secondary anti-aging agents such as

  Examples of light stabilizers and ultraviolet absorbers include 4-t-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2,2′dihydroxy-4-methoxybenzophenone, ethyl-2-cyano-3,3′-diphenyl. Acrylate, 2-ethylhexyl-2-diano-3,3'-diphenyl acrylate, 2-hydroxy-5-chlorobenzophenone, 2-hydroxy-4-methoxybenzophenone-2-hydroxy-4-octoxybenzophenone, monoglycol salicy Rate, oxalic amide, 2,2 ', 4,4'-tetrahydroxybenzophenone and the like. These stabilizers may be used alone or in combination of two or more.

  Examples of the flexibility-imparting agent include plasticizers, softeners, oligomers, oils (animal oil, vegetable oil, etc.) usually used in thermoplastic resins and rubbers, petroleum fractions (kerosene, light oil, heavy oil, naphtha, etc.). However, use of an acrylic block copolymer (A), an olefinic thermoplastic elastomer (B), a compatibilizer (C), and a polyorganosiloxane graft polymer (D) having excellent affinity. Is preferred. Among these, low-volatility plasticizers with low heat loss are adipic acid derivatives, phthalic acid derivatives, glutaric acid derivatives, trimellitic acid derivatives, pyromellitic acid derivatives, polyester plasticizers, glycerin derivatives, epoxy derivatives polyester polymerized plastics. An agent, a polyether polymerization type plasticizer and the like are preferably used.

  Examples of the softener include process oils such as paraffinic oils, naphthenic process oils, and petroleum process oils such as aromatic process oils.

  Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, di- (2-ethylhexyl) phthalate, diheptyl phthalate, diisodecyl phthalate, di-n-octyl phthalate, and phthalic acid. Phthalic acid derivatives such as diisononyl, ditridecyl phthalate, octyldecyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate; isophthalic acid derivatives such as dimethyl isophthalate; tetrahydrophthal such as di- (2-ethylhexyl) tetrahydrophthalic acid Acid derivatives: dimethyl adipate, dibutyl adipate, di-n-hexyl adipate, di- (2-ethylhexyl) adipate, dioctyl adipate, isononyl adipate, diisodecyl adipate, dibutyl diglycol adipate, etc. Dipic acid derivatives; azelaic acid derivatives such as di-2-ethylhexyl azelate; sebacic acid derivatives such as dibutyl sebacate; dodecanedioic acid derivatives; maleic acid derivatives such as dibutyl maleate and di-2-ethylhexyl maleate; fumaric acid Fumaric acid derivatives such as dibutyl; p-oxybenzoic acid derivatives such as 2-ethylhexyl p-oxybenzoate; trimellitic acid derivatives such as tris-2-ethylhexyl trimellitic acid; pyromellitic acid derivatives; citric acid derivatives such as acetyltributyl citrate Itaconic acid derivative; oleic acid derivative; ricinoleic acid derivative; stearic acid derivative; other fatty acid derivative; sulfonic acid derivative; phosphoric acid derivative; glutaric acid derivative; dibasic acid such as adipic acid, azelaic acid, phthalic acid and glycol Yo Polyester plasticizers that are polymers with monohydric alcohols, glycol derivatives, glycerin derivatives, paraffin derivatives such as chlorinated paraffins, epoxy derivatives polyester polymerized plasticizers, polyether polymerized plasticizers, ethylene carbonate, propylene carbonate Carbonate derivatives such as benzenesulfonic acid derivatives such as N-butylbenzeneamide, etc., but are not limited to these, and various types such as those widely marketed as plasticizers for rubber or thermoplastic resins These plasticizers can be used.

  Commercially available plasticizers include Thiocol TP (manufactured by Morton), Adekasizer O-130P, C-79, UL-100, P-200, RS-735 (Asahi Denka Kogyo Co., Ltd.), Sunsosizer N-400 (manufactured by Shin Nippon Rika Co., Ltd.), BM-4 (manufactured by Daihachi Chemical Industry Co., Ltd.), EHPB (manufactured by Ueno Pharmaceutical Co., Ltd.), UP-1000 (manufactured by Toagosei Co., Ltd.), etc. Is mentioned.

  Examples of the oil include vegetable oils such as castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, tall oil, sesame oil, and camellia oil.

  Examples of other flexibility imparting agents include polybutene oil, spindle oil, machine oil, tricresyl phosphate, and the like.

  Examples of the flame retardant include, but are not limited to, triphenyl phosphate, tricresyl phosphate, decabromobiphenyl, decabromobiphenyl ether, and antimony trioxide. These flame retardants may be used alone or in combination of two or more.

  The conditions for injection molding the resin boot of the present invention from the thermoplastic elastomer resin as described above are generally cylinder temperature: 150 to 230 ° C., nozzle temperature: 180 to 240 ° C., injection speed: low speed, cooling time: Examples include molding conditions such as 30 seconds, mold temperature: 30 to 80 ° C.

  The resin boot according to the present invention has excellent low-temperature characteristics, oil resistance, heat resistance, weather resistance, mechanical properties and further fatigue strength, and can be suitably used for automobile constant velocity joint boots, etc. Compared to conventional vulcanized rubber systems, it simplifies the molding process and excels in recyclability.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

  In the following, BA, MEA, MMA, and TBMA mean n-butyl acrylate, 2-methoxyethyl acrylate, methyl methacrylate, and t-butyl methacrylate, respectively.

(Molecular weight)
The molecular weight of the acrylic block copolymer was measured with a GPC analyzer (system: GPC system manufactured by Waters, column: Shodex K-804 (polystyrene gel) manufactured by Showa Denko KK). The molecular weight in terms of polystyrene was determined using chloroform as the mobile phase.

(6-membered cyclic acid anhydride group conversion analysis)
Confirmation of the 6-membered cyclic acid anhydride group conversion reaction of the acrylic block copolymer was performed by infrared spectrum analysis (manufactured by Shimadzu Corporation, using FTIR-8100) and nuclear magnetic resonance analysis (manufactured by BRUKER, AM400). Use).
As a nuclear magnetic resonance analysis solvent, a block body having a carboxylic acid ester structure was analyzed using deuterated chloroform as a measurement solvent together with a block body having a 6-membered cyclic acid anhydride structure.

<Production example of acrylic block copolymer>
After the inside of the polymerization vessel of a 500 L reactor equipped with a stirrer capable of heating and cooling was purged with nitrogen, 840.1 g (5.9 mol) of copper bromide was weighed and 12 L of acetonitrile (nitrogen bubbling) was added. After heating and stirring at 70 ° C. for 30 minutes, 421.7 g (1.17 mol) of diethyl 2,5-dibromoadipate initiator, 41.4 L (288.9 mol) BA, and 18.6 L (144.5 mol) MEA were added. It was. The mixture was heated and stirred at 85 ° C., and 0.1 L (0.59 mol) of ligand diethylenetriamine was added to initiate polymerization.

  About 0.2 ml of the polymerization solution was sampled from the polymerization solution at regular intervals from the start of polymerization, and the conversion rate of BA was determined by gas chromatogram analysis of the sampling solution. The polymerization rate was controlled by adding diethylenetriamine as needed. When the conversion rate of BA was 94% and the conversion rate of MEA was 96%, TBMA 24.9L (153.8mol), MMA 24.7L (230.8mol), copper chloride 580g (5.9mol), butyl acetate 1.2 L (9.1 mol) and 122.8 L of toluene (nitrogen bubbled) were added. Similarly, conversion rates of TBMA and MMA were determined. When the conversion rate of TBMA was 61% and the conversion rate of MMA was 56%, 80 L of toluene was added and the reactor was cooled in a water bath to complete the reaction.

The reaction solution was diluted with 115 L of toluene, 1337 g of p-toluenesulfonic acid monohydrate was added and stirred at room temperature for 3 hours, and then the solid was removed using a bag filter (HAYWARD). To the polymer solution obtained, 1642 g of an adsorbent (trade name KYOWARD 500SH, manufactured by Kyowa Chemical Co., Ltd.) was added and stirred for another 3 hours at room temperature. The adsorbent was filtered using a bag filter to obtain a colorless and transparent polymer solution. Obtained. This solution was dried using a horizontal evaporator (heat transfer area: 1 m ² ) to remove the solvent and residual monomer, thereby obtaining the target block copolymer. When the GPC analysis of the obtained block copolymer was conducted, the number average molecular weight (Mn) was 93700, and molecular weight distribution (Mw / Mn) was 1.36.

  A pressure kneader (((1A40T6.5) 700 g) and a phenolic antioxidant (trade name Irganox 1010, manufactured by Ciba Specialty Chemicals Co., Ltd.) 1.4 g were set at 240 ° C. A target 6-membered cyclic acid anhydride group-containing block copolymer was obtained by melting and kneading at 70 rpm for 20 minutes using a Moriyama Corporation DS1-5MHB-E type kneader. The block of the polymer obtained by the pressure kneader was freeze-pulverized with liquid nitrogen and a pulverizer to obtain the block copolymer pellets.

The conversion of the t-butyl ester moiety to a 6-membered cyclic acid anhydride group could be confirmed by IR (infrared absorption spectrum) analysis and ¹³ C-NMR (nuclear magnetic resonance spectrum) analysis.
That is, in the IR analysis, it was confirmed that an absorption spectrum derived from an acid anhydride group was observed around 1800 cm ⁻¹ after conversion. ^{In the 13} C-NMR analysis, it was confirmed that the 82 ppm signal derived from the methine carbon of the t-butyl group and the 28 ppm signal derived from the methyl carbon disappeared after the conversion.

Example 1
1076.9 g of the acrylic block copolymer obtained in the production example, 2153.8 g of an olefinic thermoplastic elastomer (trade name Santoprene 111-80, manufactured by Advanced Elastomer Systems), and a compatibilizing agent (ethylene-glycidyl methacrylate- (Methacrylate) 269.2 g was thoroughly mixed by hand blending so as to be uniformly dispersed. The kneading conditions were C1 to C3: 100 ° C., C4: 180 ° C., C5: 180 ° C., C6: 200 ° C., C7: 220 ° C., die head: 220 ° C., rotation speed: 150 rpm, and vented twin screw extruder “TEX30HSS- 25.5PW-2V "(manufactured by Nippon Steel Works). The extruded strand was pelletized with a pelletizer “SCF-100” (manufactured by Isuzu Chemical Industries, Ltd.) so as to facilitate injection molding. The obtained pellets were dried at 80 ° C. for 3 hours or more.

The pellets of the thermoplastic elastomer composition obtained as described above were molded into a molding metal having a structure shown in FIGS. 3 to 6 on an injection molding machine “J150E-P” (manufactured by Nippon Steel Works) with a clamping pressure of 150 TON. Using a mold, injection molding was performed under the conditions of a cylinder temperature of 150 to 230 ° C, a nozzle temperature of 230 ° C, an injection speed of 10%, a cooling time of 30 seconds, and a mold temperature of 40 ° C. The mold is removed from the core mold 20 at an air pressure of 5 kg / cm ² (0.49 MPa) emanating from the air holes 21 of the air hole 21, and the obtained molded product is a part c serving as a lid formed on the gate part, a runner part, etc. 11 was cut off from the portion of the line L in FIG. 11 to obtain a constant velocity joint boot 1 having the shape and size shown in FIGS.

(Comparative Example 1)
A constant velocity joint boot was obtained in the same manner as in Example 1 except that the curvature radius R of the valley 5c was 1.5 mm.

(Comparative Example 2 to Comparative Example 4)
A constant velocity joint boot that was injection molded under the same conditions as in Example 1 except that a cavity mold and a core mold having the joint boot shape shown in FIGS. 12 to 14 and Table 1 were used as the injection mold. Got.

The following evaluation was performed on the constant velocity joint boots of Example 1 and Comparative Examples 1 to 4 molded as described above.
(1) Flexibility The load applied when the boot was pressed down by hand from the small diameter mounting portion was measured. The smaller the load, the better the flexibility (if the flexibility is poor, it becomes difficult to attach to the shaft).
(2) Durability 1 (deformability)
The rotation amount of the drive shaft was 2000 rpm, the shaft angle was 10 °, the temperature was 80 ° C., and the maximum expansion amount (deformation amount: mm) was measured. The smaller the deformation, the better. When the deformation is large, the boot hits a peripheral member due to the centrifugal force during rotation, and the bellows part is easily cut.
(3) Durability 2 (Fatigue)
The durability of the drive shaft was measured at a rotational speed of 100 rpm, a joint angle of 40 °, and a temperature of room temperature. Durability was determined by the time taken to crack the bellows part. The longer the time it takes for the bellows to crack, the better the fatigue.

  The evaluation results are shown in Table 1.

As is clear from Table 1, the constant velocity joint boots of Example 1 and Comparative Example 1 are flexible and deformed despite the fact that the bellows portion and the mounting portion are thinner than the boots of Comparative Examples 2 to 4. Excellent in properties. From this result, the present invention, by reducing the outer diameter of the inner diameter d ₃ and crests 6c closest trough portion 5c to the portion with the large-diameter in the bellows portion 4, the expansion is prevented by the centrifugal force upon rotation At the same time, it has been clarified that a boot having excellent flexibility can be obtained by reducing the thickness of the bellows portion. Furthermore, from comparison between Example 1 and Comparative Example 1, it became clear that the fatigue property was improved by increasing the curvature radius of the valley portion 5c.

(A) is a longitudinal cross-sectional view of the boot for constant velocity joints which concerns on embodiment of this invention, (b) and (c) are expanded sectional views of the trough part nearest to a large diameter attachment part. It is a bottom view of the boot shown in FIG. It is sectional drawing of an injection mold. It is a front view of the division surface of one division type of a cavity metal mold | die. It is a front view of the division surface of the other division type | mold of a cavity metal mold | die. It is sectional drawing of the outer mold | type of a core metal mold | die. It is sectional drawing of the metal mold | die in the state which inject | poured resin. It is sectional drawing of a different angle of the metal mold | die in the state which inject | emitted resin. It is sectional drawing explaining the flow of the resin in a dome shaped gate. It is sectional drawing of the state which opened the metal mold | die after shaping | molding. It is sectional drawing which shows a mode that a molded article is demolded from a core metal mold | die by high pressure air. 5 is a longitudinal sectional view of a resin boot of Comparative Example 1. FIG. 5 is a longitudinal sectional view of a resin boot of Comparative Example 2. FIG. It is a longitudinal cross-sectional view of the resin boots of Comparative Example 3.

Explanation of symbols

1 Resin boots (Constant velocity joint boots)
2 Small-diameter mounting part 3 Large-diameter mounting part 4 Bellows part 5 Valley part 6 Mountain part 7 Projection part 8 Peripheral wall part 10 Cavity mold 20 Core mold 21 Air hole 22 Opening / closing axis 30 Molding space 40 Gate c Part L to be cut Part M Resin P Molded product

Claims (4)

A pair of attachment portions opened at both ends of the large diameter attachment portion and the small diameter attachment portion, and the large diameter attachment portion and the small diameter attachment portion are integrally connected, and the diameter is increased from the large diameter attachment portion toward the small diameter attachment portion. A boot made of a thermoplastic elastomer resin, the inner diameter d of the valley portion closest to the large-diameter mounting portion is set on the small-diameter mounting portion side of the bellows portion. It is larger than the opening diameter D ₁ and 60% or less of the opening diameter D ₂ on the large diameter attachment portion side in the bellows portion, and the curvature radius of the valley portion closest to the large diameter attachment portion is 2 to 10 mm. Characteristic resin boots. The large diameter mounting portion of the outer diameter of the nearest crests, the resin boot as claimed in claim 1, wherein comprising smaller than the opening diameter D ₂ of the large-diameter mounting portion side of the bellows portion.   The resin boot according to claim 1 or 2, wherein a thickness of the bellows portion is 3 mm or less. The resin boot according to any one of claims 1 to 3, wherein a cylindrical peripheral wall portion extending in parallel with the axial center of the boot is formed at an opening edge of the bellows portion on the large diameter attachment portion side.

Images