JPH0341499B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel thermoplastic elastomeric composite that is inexpensive, highly flexible, and has excellent heat aging resistance and mechanical strength. Specifically, the present invention relates to a method for adding a large amount of a softening agent to a hydrogenated derivative of a specific block copolymer in a simple manner. In recent years, thermoplastic elastomers (hereinafter abbreviated as TPE), which are rubber-like materials that do not require a vulcanization process and have moldability similar to thermoplastic resins, have been developed.
are used in various fields such as automobile parts, home appliance parts, electric wire coatings, footwear, and miscellaneous goods. Currently, various types of polymers such as polyolefin, polyurethane, polyester, polystyrene, and polyvinyl chloride have been developed and commercially available for such TPE. Among these, styrene-butadiene block copolymer (SBS) and styrene-isoprene
Styrenic TPE such as block copolymer (SIS)
is the most flexible of the various TPEs and has good rubber elasticity at room temperature, and the TPE composition obtained from it has excellent moldability. However, this TPE has a double bond as a conjugated diene block within the polymer molecule, so there are problems with heat aging resistance (thermal stability) and weather resistance, so this double bond is removed by hydrogenation. TPE has been developed to improve this drawback. Since this material is expensive, several methods have been proposed in which a softening agent such as hydrocarbon oil is added to form a composite material (for example, JP-A-50-14742 and JP-A-52-65551). Generally, when blending a large amount of softener into TPE, mechanical kneading methods such as internal kneading machines (e.g. Banbury mixer) or extruder-type kneading machines widely used in the rubber industry, and TPE using a solvent. A solution blending method is used in which the resin is dissolved in water and mixed with a softening agent. However, these methods have the following drawbacks. When blending a softener into synthetic rubber materials using a mechanical kneading method, a Banbury mixer is generally used, but due to constraints in terms of the quality of the resulting product, the softener is added to 100 parts by weight of the synthetic rubber material. It is usual to mix up to about 120 parts by weight at most. Even if a larger amount of softener is blended, it is impossible to mix uniformly and the surface becomes highly sticky, making it difficult to apply it successfully in subsequent steps. In addition, when mixing using an extruder, from the perspective of blending a large amount of softener, the short residence time makes it difficult to expect sufficient mixing, and the softener may be directly discharged from the tip of the extruder. . Furthermore, when using a Banbury mixer,
Production on a commercial scale requires a large amount of equipment (generally an investment in the hundreds of millions of yen). Therefore, it is desirable to use a method that does not use a Banbury mixer as much as possible. On the other hand, the solution blending method is the best in terms of obtaining a homogeneous composition, but the composition obtained by this method has a sticky surface, which hinders the storage process and subsequent processes. Not only does it cause problems, but it also requires a large amount of equipment and a complicated process of removing the solvent, making it an irrational method from an industrial perspective. In order to eliminate these drawbacks, the present invention allows a large amount of softener to be added to TPE simply and economically, and the resulting composition also contains the softener uniformly, and
This research was carried out with the aim of developing a method that would prevent the surface from becoming sticky. That is, the present invention is based on (a) the general formula A-(B-A) _o (where A is a monovinyl-substituted aromatic hydrocarbon polymer block, B is a conjugated diene elastomeric polymer block, and n is It is an integer from 1 to 5.)
(b) 80 to 300 parts by weight of a non-aromatic rubber softener to 100 parts by weight of a hydrogenated derivative of a block copolymer represented by the formula, which has a crumb-like shape and a bulk specific gravity of 0.3 or less. , a method for adding a softener to an elastomer, characterized in that component (b) is impregnated in liquid form at a temperature of 150°C or lower. By the method of the present invention, it is possible to uniformly contain an unprecedentedly large amount of softener in TPE in an extremely simple and economical manner without using extensive equipment, and to obtain a TPE composition without surface stickiness. be able to. A composition with good mechanical strength can also be obtained. Component (a) used in the present invention has the general formula A-(B-A) _o (where A is a polymer block of a monovinyl-substituted aromatic hydrocarbon, and B is an elastomeric copolymer block of a conjugated diene. , n is 1
It is a hydrogenated derivative of a block copolymer represented by: The monomer of block A in the polymer is a monovinyl-substituted aromatic hydrocarbon, preferably styrene, and α-methylstyrene or the like may also be used. The conjugated diene monomer in polymer block B is preferably butadiene or isoprene,
Alternatively, a mixture of both may be used. Polymer block B
When butadiene is used as the single conjugated diene to form a polybutadiene block, the microstructure in the polybutadiene block after the block copolymer is hydrogenated to saturate the double bonds to impart elastomeric properties. Medium 1,2 - Microstructure is 20
It is preferable to adopt polymerization conditions such that the 1,2-microstructure is 35 to 45%.
%belongs to. The number average molecular weight of polymer block A in the block copolymer is 5,000 to 125,000, and that of block B is 15.
Preferably, the range is from 000 to 250,000. Many methods have already been proposed for producing these copolymers, but representative methods include those described in Japanese Patent Publication No. 40-23798, and
As a hydrogenation method, Japanese Patent Publication No. 42-8704, No. 43-
There are methods described in 6636 and 46-20814. This hydrogenation is such that at least 50%, preferably at least 80%, of the olefinic double bonds in polymer block B have been hydrogenated, and no more than 25% of the aromatic unsaturation in polymer block A has been hydrogenated. Reduced by hydrogenation. In addition, the proportion of polymer block B in the total copolymer is at least 65
Weight%. One such hydrogenated block copolymer is commercially available from Shell Chemical Company under the trade name "KRATON-G." In addition, the softener that is component (b) used in the present invention is
It is used for non-aromatic rubbers, and mineral oil-based or synthetic resin-based ones are suitable. Mineral oil-based softeners are a combination mixture of aromatic rings, naphthenic rings, and paraffin chains, and those in which the paraffin chain carbon number accounts for 50% or more of the total carbon are called paraffinic softeners. Those with a carbon number of 30 to 45% are called naphthenic, and those with more than 30% aromatic carbon are called aromatic. Among these, mineral oil softeners preferred as component (b) of the present invention are naphthenic and paraffinic softeners, and have an aromatic carbon number of 30%.
These are as follows. Aromatic types are not very preferable from the viewpoint of dispersion with the component (a) used in the present invention. In terms of properties, the kinematic viscosity at 37.8℃ is 20~500cst, the pour point is -10~-15℃, and the flash point (COC) is 170~
It's like 300℃. As the synthetic resin softener, polybutene, low molecular weight polybutadiene, etc. can be used, but mineral oil softeners are preferred. The amount of the softener (component (b)) is 80 to 300 parts by weight, preferably 100 to 200 parts by weight, based on 100 parts by weight of component (a). If it exceeds 300 parts by weight, the softener tends to bleed out, making the final product sticky and reducing its mechanical strength, which is not preferable. In addition to the above components, for the purpose of further improving mechanical strength, heat resistance, moldability, etc., other synthetic resins, such as olefin polymers such as polyethylene and polypropylene, or other synthetic rubbers, such as styrene, etc. Butadiene rubber (SBR), butadiene rubber (BR), ethylene propylene rubber (EPM,
EPDM), etc., or various inorganic fillers such as calcium carbonate, talc, mica, etc. can be optionally blended to meet the purpose. The general blending amount of these is 30 to 400 parts by weight for synthetic resins per 100 parts by weight of component (a).
In the case of synthetic rubber, the amount is preferably 5 to 100 parts by weight, and in the case of inorganic filler, it is preferably about 10 to 900 parts by weight in terms of balance of flexibility, mechanical strength, heat resistance, etc. Next, the method for adding component (b) above to component (a) is to impregnate component (a) with component (b) in liquid form, but care must be taken when performing this operation. The following two points are important. First, it is important that the polymer of component (a) has a crumb-like appearance. The state of impregnation of component (b) into component (a) is greatly influenced by the surface state of the polymer particles of component (a). If component (a) is not crumb-like, for example, pellet-like, the impregnation time will be very long. Not only does this take a long time to process, making it impractical, but in some cases, it may not be impregnated at all. The term “crumb-like” here refers to the “Polymer Dictionary” (Showa era).
As shown on page 188 of ``Asakura Shoten, published in 1946, edited by the Society of Polymer Science and Technology'', it refers to rubber that is separated into small lumps with low bulk specific gravity after polymerization and before the drying process in the manufacturing process of synthetic rubber, etc. In the case of component (a), it refers to a crumb-like porous material with a bulk specific gravity of 0.3 or less and a particle size of approximately 20 mm or less, preferably 10 mm or less. Second, if component (a) and component (b) come into contact and the temperature of the homogenized atmosphere is higher than 150℃, not only will the impregnation time of component (b) become very long, but the final Even if impregnated somehow, the surface of the resulting composition becomes sticky, the crumb shape collapses, and it becomes plate-like, which hinders subsequent operations. Therefore, this impregnation operation is preferably carried out at a temperature of 150°C or lower, preferably 100°C or lower. The most economical and preferable method is to carry out the reaction at around room temperature without heating. Such an impregnation method is a very simple method and has the advantage that it does not require any particularly large special equipment. In other words, on a laboratory scale,
Weigh the specified amounts of component (a) and component (b), and at around room temperature,
The two may be brought into direct contact in a beaker. At this time, the contents in the beaker (a mixture of component (a) and component (b)) may be stirred, or may be left as is. Approximately 10~ in this condition
After 15 minutes, the large amount of softener is completely impregnated into component (a), and there is no apparent change in appearance, except that the initial particle size of component (a) becomes slightly larger due to swelling. Moreover, the crumb-like composition itself after being impregnated with component (b) has no stickiness on the surface, even though it contains a large amount of component (b). Even the softener slightly attached to the beaker wall etc. is impregnated without any trace. As mentioned above, the impregnation method can be carried out in a static state, but on an industrial scale,
This is generally carried out using a Henschel mixer, ribbon blender, tumbling blender, or other device with a stirring function.At this time, it is convenient to carry out the impregnation with the other ingredients mentioned above mixed according to the purpose. be. The composition obtained by the method of the present invention is an elastomeric composition that exhibits sufficient thermoplasticity, is highly flexible, and has excellent heat deformation resistance, and can be molded with a commonly used thermoplastic resin molding machine. Various molding methods such as injection molding, extrusion molding, blow molding, and calendar molding can be applied. The molded product thus obtained can be used for various electric wire coatings (insulation, sheath), household appliance parts, automobile parts, and other industrial parts. Specific applications include various gaskets, flexible tubes, hose coverings, weather strips,
Includes flexible bumpers, side bumpers, moldings, filler panels, lamp housings, wire cable coverings, air intake hoses, etc. Examples 1 to 3, Comparative Examples 1 and 2 As component (a), KRATON-G1651 (crumb-like,
Put 100 parts by weight (20 g) of bulk specific gravity 0.25, manufactured by SHELLCHEMICAL Co., Ltd. and 80 to 400 parts by weight of paraffin oil PW90 (manufactured by Idemitsu Kosan Co., Ltd.) as component (b) into a 100 c.c. beaker equipped with a stirrer, and stir at 50 rpm. Impregnation was carried out while stirring. The ambient temperature was 20.5°C. The results are shown in Table 1. In addition, KRATON−
In G1651, in the general formula, A is a styrene polymer block, B is a butadiene polymer block,
It is a hydrogenated derivative where n is 1, the total amount of styrene polymer blocks at both ends is about 33% by weight, and the Brookfield viscosity in 20% toluene solution (77〓) is
It is of 2000cps.

[Table] Comparative Example 3 Using the same blending ratio as Example 1 and using a Prabender Plastograph (100 c.c. capacity), 50 rpm,
The mixture was kneaded at 200°C for 7 minutes to obtain a composition. This composition and the composition of Example 1 were molded using a press molding machine, 10 cm wide x 10 cm long x 2 mm thick.
I made a sample. The press molding conditions were 100 kg/cm ² , 200° C., and 5 minutes. Using this sample, tensile properties and hardness were measured in accordance with JIS-K6301. The results are shown in Table 2.

[Table] *Due to the ability of the measuring device, it is possible to measure values higher than this.
I couldn't do it.
Example 4, Comparative Examples 4 and 5 KRATON-G1651 (crumb-like) was granulated at 220°C using a twin screw extruder PCM30 manufactured by Ikegai Iron Works. This pellet and crumb-like KRATON-G1651
and crumb-like ethylene-propylene copolymer rubber (EPM, EP02C manufactured by Mitsubishi Yuka Co., Ltd.).
180 parts by weight of PW90, which is the component (b) used in Example 1, was added to 100 parts by weight of each of these, and the impregnation operation was carried out in the same manner as in Example 1. The results are shown in Table 3.

【table】

【table】

Claims (1)

[Claims] 1 (a) General formula A-(B-A) _o (where A is a monovinyl-substituted aromatic hydrocarbon polymer block, B is a conjugated diene elastomeric polymer block, and n is 1 to 5. 100 parts by weight of a hydrogenated derivative of a block copolymer represented by (an integer) having a crumb-like shape and a bulk specific gravity of 0.3 or less, (b) 80 parts by weight of a non-aromatic rubber softener. ~300 parts by weight,
A method for adding a softener to an elastomer, which comprises impregnating the component (b) in liquid form at a temperature of 150°C or lower.