JPH08176350A - Continuous production of rubber composition - Google Patents

Abstract

PURPOSE: To continuously and efficiently obtain a rubber composition according to simple means by feeding a vulcanizable rubber and a thermoplastic resin to a twin-screw kneading extruder and carrying out the mastication of the rubber and melt kneading thereof with the resin. CONSTITUTION: (A) A vulcanizable rubber (preferably a natural rubber, a butadiene rubber, etc.) and (B) a thermoplastic resin (e.g. a polyolefin or a polyamide) are fed to a twin-screw kneading extruder to carry out the mastication of the component (A) and the melt kneading of the masticated component (A) with the component (B). The ratio of the component (B) used is preferably 50-150 pts.wt. based on 100 pts.wt. component (A). Furthermore, the mastication of the component (A) is preferably carried out in the first kneading zone 6 on the upstream side of the twin-screw kneading extruder 1 and the melt kneading of the components (A) with (B) is preferably performed in the second and third kneading zones 7 and 8 on the downstream side thereof by installing two or more hoppers 2-4 in the twin-screw kneading extruder 1, feeding the component (A) from the hopper 2 on the upstream side in the extruding direction and simultaneously feeding the component (B) from the hoppers 3 and 4 on the downstream side thereof.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for continuously producing a rubber composition by simple means. The rubber composition produced according to the present invention can be suitably used as a raw material for preparing various molded articles.

[0002]

BACKGROUND OF THE INVENTION In Japanese Patent Publication No. 1-17494, a vulcanizable rubber, a polyamide, and a small proportion of an alkylphenol formaldehyde resin are kneaded at a temperature not lower than the melting point of the polyamide, and the kneaded product is a polyamide. A method for producing a rubber composite reinforced with polyamide fibers is disclosed by extruding at a temperature equal to or higher than the melting point of, and stretching the extrudate at a temperature lower than the melting point of polyamide.

In column 7, lines 37 to 41 of the above publication, a Brabender-Plastograph is used as a kneading machine used when kneading a vulcanizable rubber, a polyamide, and an alkylphenol formaldehyde-based resin agent. An extruder is also disclosed, along with a Banbury mixer and roll.

However, in all the examples of the above publications, mastication of vulcanizable rubber and kneading with polyamide are carried out by a batch type Brabeda-Plastograph.
There is no mention or suggestion in this publication of the use of a twin-screw kneading extruder capable of continuous kneading.

[0005]

One of the reasons why a twin-screw kneading extruder is not used when kneading rubber and a thermoplastic resin is that the molding machine used is different between the rubber industry and the plastics industry. It is that. That is, Brabender-Plastograph or Banbury mixers are used only in the rubber industry and twin-screw kneading extruders are used exclusively in the plastics industry. Therefore, it is presumed that the use of the twin-screw kneading extruder for masticating the rubber and melt-kneading the masticated rubber and the thermoplastic resin was not considered in both the rubber industry and the plastics industry.

[0006]

DISCLOSURE OF THE INVENTION The present invention is based on the finding that mastication of rubber and melt kneading of masticated rubber and thermoplastic resin can be continuously and efficiently performed by a twin-screw kneading extruder. ing.

That is, according to the present invention, a vulcanizable rubber and a thermoplastic resin are fed to a twin-screw kneading extruder to masticate the vulcanizable rubber, and the masticated vulcanizable rubber and the thermoplastic resin. It is a continuous method for producing a rubber composition, which comprises melt-kneading with a resin.

The glass transition temperature of the vulcanizable rubber is preferably 0 ° C. or lower, particularly -20 ° C. or lower. Specific examples thereof include natural rubber, isoprene rubber, butadiene rubber, styrene / butadiene rubber, acrylonitrile / butadiene rubber, butyl rubber, chlorinated butyl rubber, chloroprene rubber, ethylene / propylene rubber, ethylene / propylene / diene rubber, ethylene / butene rubber, ethylene. -Butene / diene rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, etc. may be mentioned.

Of these, natural rubber, butadiene rubber, acrylonitrile / butadiene rubber, ethylene / propylene rubber and ethylene / propylene / diene rubber are preferably used. These may be used alone,
You may use it in combination of 2 or more type.

The vulcanizable rubber is cut with a cutting machine such as a guillotine cutter before being fed to a twin-screw kneading extruder, and then cut with a crusher into an appropriately large, for example, 5-20 mm average equivalent diameter. Preferably.

The vulcanizable rubber may contain additives known per se, such as antioxidants.

There is no particular limitation on the thermoplastic resin, for example, polyethylene, polyolefin such as prepropylene, nylon 6, nylon 66, nylon 1
In addition to polyamides such as 2, polyvinyl chloride, polyacetal, polyethylene terephthalate, polycarbonate, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin can be mentioned. These thermoplastic resins may be used alone or in combination of two or more kinds.

The thermoplastic resin is used in an amount of 300 parts by weight or less, particularly 50 to 100 parts by weight, per 100 parts by weight of the vulcanizable rubber.
It is preferably 150 parts by weight. If the proportion of the thermoplastic resin used is too high, the resulting rubber composition tends to have poor creep resistance.

The twin-screw kneading extruder used in the present invention is a device known per se, and is a kneading extruder having two screws rotatable in the same direction or different directions. Specific examples of the twin-screw kneading extruder include TEX manufactured by Japan Steel Works
System extruder, TEM system extruder manufactured by Toshiba Machine, PTE system extruder manufactured by Mitsubishi Heavy Industries, and UME extruder manufactured by Ube Industries.

There is no particular limitation on the means for supplying the vulcanizable rubber and the thermoplastic resin to the twin-screw kneading extruder,
Both can be simultaneously supplied from a hopper provided in the twin-screw kneading extruder, and two or more hoppers can be supplied to the twin-screw kneading extruder.
It is also possible to supply vulcanizable rubber from the hopper on the upstream side in the extrusion direction and to supply the thermoplastic resin from the hopper on the downstream side in the extrusion direction.

In the manufacturing method of the present invention, the vulcanizable rubber and the thermoplastic resin are preferably supplied to the twin-screw kneading extruder by the latter means. According to this aspect,
Only mastication of the vulcanizable rubber supplied to the twin-screw kneading extruder is performed on the upstream side of the twin-screw kneading extruder, and then vulcanization is possible in which the muni-viscosity is reduced to some extent by mastication. Since the rubber and the thermoplastic resin are melt-kneaded, the vulcanizable rubber and the thermoplastic resin can be kneaded more smoothly.

The vulcanizable rubber and the thermoplastic resin must be kneaded at a temperature equal to or higher than the melting point of the thermoplastic resin. This makes it possible to obtain a rubber composition in which the vulcanizable rubber and the thermoplastic resin are uniformly mixed and dispersed. The Mooney viscosity of the vulcanizable rubber can be lowered also in the process of melt-kneading with the thermoplastic resin.

The rubber composition is extruded in the form of strands or sheets from a die attached to the tip of the twin-screw kneading extruder. The rubber composition extruded in the form of strands can be cut into pellets if necessary. When a polyolefin is used as the thermoplastic resin, the polyrheophine has a strong effect of reducing the tackiness of the rubber, and the extrudate can be more smoothly pelletized.

The rubber composition obtained in the present invention is disclosed in Japanese Patent Publication No.
It is suitable as a raw material for preparing a rubber composite reinforced with a polyamide fiber, which is described in JP-A-17494 and JP-A-4-33300.

The above rubber composite comprises a vulcanizable rubber and a polyamide as a thermoplastic resin, an initial condensate of a phenol formaldehyde resin acting as a binder between the rubber and the polyamide, a silane coupling agent, Titan
It can be prepared by treating with a twin-screw kneading extruder according to the present invention in the presence of a coupling agent, unsaturated carboxylic acid, organic peroxide, etc. and extruding into a sheet or strand.

The rubber composition obtained in the present invention was previously proposed by the present applicant as Japanese Patent Application No. 6-70810,
It can be suitably used as a raw material for preparing a fiber-reinforced elastic body in which polyamide fibers are dispersed in a matrix of vulcanizable rubber and polyolefin.

The above-mentioned fiber-reinforced elastic body is prepared by previously treating a vulcanizable rubber, a polyolefin and a polyamide in the presence of the binder, or a vulcanizable rubber, a polyolefin and / or a polyolefin and / or a polyamide. The treated product can be prepared according to the present invention by treating it with a twin-screw kneading extruder and extruding it into a sheet or strand. The extrudate can optionally be stretched and / or rolled at a temperature below the melting point of the polyamide.

The method for producing the rubber composition of the present invention will be described below.
A description will be given based on the embodiment shown in FIG.

A first feed port 2, a second feed port 3 and a third feed port 4 are attached to a twin screw kneading extruder 1 having a twin screw screw (not shown) installed therein. A die 5 having a plurality of holes is installed at the tip of the twin-screw kneading extruder. The twin-screw kneading extruder 1 has three kneading zones, that is, a first kneading zone 6, a second kneading zone 7 and a third kneading zone 8. 9
Is a strand cooler and 10 is a pelletizer.

The vulcanizable rubber and the antioxidant are supplied to the first kneading zone 6 of the twin-screw kneading extruder 1 from the first supply port 2 by the constant quantity feeders 11 and 12, respectively. The polyolefin and the binder for polyolefin are supplied from the second supply port 3 to the second kneading zone 7 of the twin-screw kneading extruder 1 by the constant quantity feeders 13 and 14, respectively. Further, the polyamide and the binder for polyamide are supplied to the third kneading zone 8 of the twin-screw kneading extruder 1 from the third supply port 4 by the constant quantity feeders 15 and 16, respectively.

In the first kneading zone 6 of the twin-screw kneading extruder 1,
The vulcanizable rubber is masticated, and the masticated vulcanizable rubber is sent to the second kneading zone. In the second kneading zone 7, the masticated vulcanizable rubber and the polyolefin are melt-kneaded in the presence of the binder for polyolefin, and the polyolefin is chemically bonded to the vulcanizable rubber. The resulting melted mixture of vulcanizable rubber and polyolefin is fed to the third kneading zone 8.

In the third kneading zone 8, a melt mixture of a vulcanizable rubber and a polyolefin and a polyamide is melt-kneaded in the presence of a binder for polyamide to obtain a vulcanizable rubber, a polyamide and a polyolefin. A rubber composition is obtained which is chemically bonded to each other.

As described above, further, as will be understood from the results of Reference Examples 1 to 3 described later, not only in the first kneading zone 6 but also in the second kneading zone 7 and the third kneading zone 8. ,
The screw of the twin-screw kneading extruder 1 can be used so that the vulcanizable rubber can be masticated and the Mooney viscosity of the vulcanizable rubber in the obtained rubber composition becomes a desired value. The configuration is adjusted.

The obtained rubber composition is extruded in a strand form from a die 5 having circular holes, usually at a draft ratio of 5 to 20, cooled by a strand cooler 9, and then is pelletized by a pelletizer 10. It is cut into pellets.

[0030]

EXAMPLES Examples and comparative examples will be shown below. In the examples and comparative examples, the device shown in FIG. 1 was used. The terms used in Examples and Comparative Examples are defined as follows.

Required power: Net power obtained by subtracting the power consumption during no-load operation from the power required to operate the twin-screw kneading extruder and the Banbury type mixer was converted into per rubber composition pellets and shown as the required power. It was

Pelletization: The shape of the rubber composition pellet (hereinafter simply referred to as "pellet") and the cohesiveness of the pellets were visually evaluated and evaluated as follows. ⊚: No problem at all, ∘: No problem in practical use, ×: Pellets are slightly uneven in shape, or agglomeration of pellets is observed.

Melt Viscosity: The melt viscosity of the pellet was measured by using a capillaryography (manufactured by Toyo Seiki Co., Ltd., nozzle diameter = 1 mm, L / D = 10) at a temperature of 245 ° C. and a shear rate of 121 s ⁻¹ .

Dispersibility: 10 g of pellets were refluxed at 100 ° C. in a mixed solvent of o-dichlorobenzene and xylene (volume ratio 50/50) to extract and remove vulcanizable rubber and polyolefin in the pellets. . The remaining fiber was weighed (Fg). This operation was performed on 10 samples, and the average value (FAg) and the weighing result (FMg) that caused the maximum error with the average value were obtained, and the ratio of FM to FA was taken as the dispersion rate.

Average fiber diameter: The fibers obtained in the above-mentioned dispersibility evaluation were observed with an electron microscope, and the average fiber diameter of 200 dispersed fine fibers was measured from an electron microscope image.

Bonding ratio: NMR of the fiber obtained in the above-mentioned dispersibility evaluation was measured, and it was derived from a vulcanizable rubber, a polyolefin, a modifier for polyolefin and a modifier for polyamide together with a peak derived from polyamide. A peak was observed. From these results, the binding amount of the fiberized polyamide with the vulcanizable rubber and the polyolefin was shown as the ratio to the fiberized polyamide.

Moldability: The pellets were hot pressed at 180 ° C. to prepare a sheet, and the smoothness of the sheet surface was visually observed and evaluated as follows. ⊚: sheet surface is very smooth ∘: smooth surface ×: roughness is observed

Mechanical Properties: Pellets were formed into a sheet by a roll mixer, and a test piece in a parallel direction was cut out in a fiber orientation direction, and tensile breaking strength and elongation were measured according to ASTM D638.

Mooney viscosity: Measured according to JIS-K6300 and expressed as ML _{1 + 4} .

Example 1 700 × 350 × 150 mm veiled natural rubber (N
R, SMR-L, ML _{1+ 4} = 100) with a primary crusher (Horai Co., EH-6090) having an average of 50 mm.
After crushing to φ, it was subsequently crushed to an average of 10 mmφ with a secondary crusher (BO-2572 manufactured by Horai Co., Ltd.).

In order to prevent the crushed rubbers from sticking to each other and lumping when crushing the natural rubber, polypropylene (Ube Industries, Ube Polypro, J109G, melting point 165-170 ° C., MFI = 9 g / 10 minutes of powder was fed to the crusher with rubber. The supply amount of polypropylene powder was 50 parts by weight with respect to 100 parts by weight of rubber. After crushing the crushed natural rubber to remove excess polypropylene powder, 10.0 kg / h
At a rate of r, a constant amount was supplied from the hopper-2 to the zone 6 of the twin-screw kneading extruder 1 by the constant amount supply device 11.

As the natural rubber anti-aging agent (A0), 1 part by weight of N-phenyl-N '-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine is used with respect to 100 parts by weight of natural rubber. (Nocrac G1 manufactured by Ouchi Shinko Co., Ltd.) was quantitatively supplied from the hopper-2 to the zone 6 at the same time by the constant quantity feeder 12.

The same polypropylene pellets as described above were quantitatively supplied from the hopper-3 to the zone 7 of the twin-screw kneading extruder 1 at a rate of 75 parts by weight per 100 parts by weight of natural rubber. As a polypropylene denaturant, 0.5 parts by weight of γ-methacryloxypropyltrimethoxysilane (KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) per 100 parts by weight of polypropylene was simultaneously fed from the hopper-3 to the zone 7 by the constant quantity feeder 14. Was quantitatively supplied.

Nylon 6 (Ube nylon, 1 manufactured by Ube Industries, Ltd.) dried at 70 ° C. for 72 hours under a vacuum of 10 torr.
030B, melting point 215 to 220 ° C, average molecular weight 3,0.
00) was quantitatively supplied from the hopper 15 to the zone 8 of the twin-screw kneading extruder 1 at a rate of 87.5 parts by weight per 100 parts by weight of natural rubber. Further, as a modifying agent for nylon 6, 0.7 parts by weight of N-β (aminoethyl) γ-aminopropyltrimethoxysilane (made by Shin-Etsu Chemical Co., Ltd., KBM6 per 100 parts by weight of nylon 6) is used.
03) was quantitatively supplied to the zone 8 simultaneously from the hopper-4 by the constant quantity feeder 16.

As the twin-screw kneading extruder 1, U manufactured by Ube Industries, Ltd.
ME50-60T (55 mmφ, L / D = 60) was used, a die having 10 holes of 3 mmφ was installed at the exit of the twin-screw kneading extruder 1, and the kneading extrudate was extruded in a strand shape with a draft ratio of 10. It was When the operation was stable, pelletization was performed by using a pelletizer. The physical properties of the pellets were measured. The hoppers-2 and 3 were provided with sampling ports for sampling the kneaded composition of the twin-screw kneading extruder 1.

The screw configuration of the twin-screw kneading extruder 1 is a strong kneading type (strong) type having three kneading zones corresponding to each of the zones 6, 7 and 8 and the operating conditions are the screw rotation speed. Was set to 200 rpm, and the set temperature was set to 150 ° C. in zone 6, 180 ° C. in zone 7, and 240 ° C. in zone 7. Table 1 shows the operating conditions of the twin-screw kneading extruder 1, and Table 2 shows the results.
Shown in

Examples 2 to 8 Rubber compositions were obtained in the same manner as in Example 1 except that the operating conditions were changed as shown in Table 1. Table 2 shows the results.

Comparative Example 1 This comparative example shows the results of masticating natural rubber using a Banbury type mixer according to a known method without using a twin-screw kneading extruder. The pre-propylene and nylon 6 used were pelletized after melt-kneading the same proportion of the modifying agent as in Example 1.

The same natural rubber as in Example 1 was ML
Mastication was carried out with a Banbury mixer until _{1 + 4} became 68. Next, 75 parts by weight of modified polypropylene pellets per 100 parts by weight of natural rubber was put into a Banbury mixer, melt-kneaded at 170 ° C., and then molded into pellets.

175 parts by weight of the pellets and 87.5 parts by weight of the modified nylon 6 pellets were melt-kneaded by a twin-screw kneading extruder set at 240 ° C., extruded in a string shape, and drawn into pellets at a draft ratio of 10. Table 2 shows the results.

[0051]

[Table 1]

[0052]

[Table 2]

Reference Examples 1 to 3 These Reference Examples show the results of masticating a vulcanizable rubber in each kneading zone of the twin-screw kneading extruder 1. In these reference examples, the strand curler 9 and the pelletizer 10 were separated from the twin-screw kneading extruder 1.

The same natural rubbers and antioxidants as in Example 1 were used, respectively, without the use of polypropylene and nylon 6 and their modifiers, 10.0% respectively.
Twin screw kneading extruder 1 at a rate of kg / h and 0.1 kg / h
Example 1 was repeated except that the mixture was supplied to the first kneading zone 6 of No. 1 and operated under the operating conditions shown in Table 3.

The masticated natural rubber was taken out as a sample from the outlets of the second supply port 3, the third supply port 4 and the die 5 and its Mooney viscosity was measured. The results are shown in Table 3. From Table 3, the natural rubber was melted in the flow direction in the twin-screw kneading extruder 1.
It can be seen that the two-viscosity is lowered and the mastication is progressing.

[0056]

[Table 3]

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Twin-screw kneading extruder 2 1st feed port 3 2nd feed port 4 3rd feed port 5 Dai 6 1st kneading zone 7 2nd kneading zone 8 3rd kneading zone 9 Strand cooler 10 Pelletizer 11, 12, 13, 14, 15, 16 constant quantity feeder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Matsuzaki 1980, Okiyama, Ogushi, Ube City, Yamaguchi Prefecture Ube Industries, Ltd.

Claims (1)

[Claims] 1. A vulcanizable rubber and a thermoplastic resin are fed to a twin-screw kneading extruder to masticate the vulcanizable rubber, and melt the masticated vulcanizable rubber and a thermoplastic resin. A continuous method for producing a rubber composition, which comprises kneading.