CN113942214A

CN113942214A - Method and equipment for mixing rubber by double-screw extruder

Info

Publication number: CN113942214A
Application number: CN202110927034.5A
Authority: CN
Inventors: 王若愚
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2022-01-18

Abstract

The invention relates to a method for mixing rubber by a double-screw extruder, which comprises the following steps: (1) preparing mixed master batches, namely uniformly mixing the pre-prepared master batch A and the master batch B according to a formula ratio to prepare the mixed master batches; (2) and (3) placing the uniformly mixed master batch into a feed hopper of a double-screw extruder, performing extrusion operation, synchronously completing a mixing process through the mixing action of screws, and extruding to obtain the rubber compound. The master batch A in the step (1) is a pre-dispersed master batch which contains rubber, EVA or other additives but no sulfur and is subjected to uniform mixing and granulation; the master batch B in the step (2) is pre-dispersed master batch which contains EVA and sulfur or other auxiliary agents and is subjected to uniform granulation. By applying the method, the rubber can be fully and uniformly mixed by using a double-screw extruder, and the rubber compound can be prepared. The invention also provides complete equipment for mixing rubber by the double-screw extruder.

Description

Method and equipment for mixing rubber by double-screw extruder

Technical Field

The invention relates to the field of rubber processing technology, in particular to a method and equipment for mixing rubber by using a double-screw extruder.

Background

The conventional rubber mixing is carried out by using an internal mixer or an open mill under high shear for a long time. The traditional mixing method is based on intermittent operation, needs a large amount of manpower, and has large occupied area and low overall economy.

Because the rubber is massive mostly, the feeding of the rubber in the twin-screw is inherently difficult, and simultaneously because the rubber auxiliaries are various, most of the rubber auxiliaries are powdery, and the density of the rubber auxiliaries is also greatly different, the raw materials with different particle sizes and different densities are fed into the twin-screw, or the raw materials are very easy to generate gradient layering during premixing, and the uniformity of rubber mixing by using the twin-screw is seriously influenced.

CN201910540908.4 relates to a preparation method of a novel vulcanization system TPV material, which at least comprises the following steps: (1) plasticating: adding 10 parts by weight of ethylene propylene diene monomer and 1-5 parts by weight of butadiene rubber into a single-screw extruder, adding 5-14 parts by weight of white oil, and performing oil flushing treatment at 70-90 ℃ to obtain a rubber component; (2) mixing: adding the rubber component obtained in the step (1) into a double-screw extruder, adding (1-3) parts by weight of polypropylene, (0.1-0.5) parts by weight of grafted polypropylene, (3-8) parts by weight of hydrogenated styrene-butadiene block copolymer, (0.1-0.4) parts by weight of vulcanizing agent, (0.1-0.4) parts by weight of vulcanization accelerator, (0.01-0.15) parts by weight of antioxidant and (3-12) parts by weight of filler, mixing at 165-200 ℃, granulating and vulcanizing to obtain the TPV material. In the background technology, a double-screw extruder is selected as mixing equipment to prepare the TPV, and the mixing and vulcanization of rubber are realized at a higher temperature, but the method does not solve the problem of uniform feeding, does not solve the problem of uniform mixing while avoiding rubber vulcanization, is only suitable for preparing the TPV, requires certain compatibility when preparing the TPV, is not suitable for preparing the TPV on the contrary due to too high compatibility, and has the core purpose of dynamic vulcanization, which is completely different from the mixing of the rubber, so the method has no substantial suggestion on the mixing of the rubber.

CN201810127368 provides a preparation method of a rubber material for machinery, which comprises the following steps: a. mixing and mixing the epoxy natural rubber, the ethylene propylene rubber and the styrene butadiene rubber, adding the modified clay emulsion, and stirring to obtain a mixture I; b. mixing the modified rubber emulsion, the modified asphalt emulsion, the coupling agent and the defoaming agent, stirring and heating to obtain a second mixture; c. mixing and pulping diatomite, silicon dioxide powder, an anionic surfactant and deionized water, adjusting the pH, adding a composite material, and stirring to obtain a third mixture; d. and (3) introducing the mixture I, the mixture II and the mixture III into a mixer, adding a cross-linking agent, stirring and mixing, and then extruding and molding by using a double-screw extruder. The background technology is that the components such as rubber are made into emulsion and mixed and then extruded, and the method does not solve the problem of rubber mixing.

CN201611156530 discloses a three-phase material rubber continuous mixing roll for preparing a rubber compound based on a strip-shaped raw rubber, which comprises a screw cylinder with a feeding bin, a double screw, a driving device, and a three-phase material continuous weighing and mixing system connected with the feeding bin and used for continuously, automatically, accurately and uniformly mixing materials and continuously conveying the materials into the continuous mixing roll. The background technology realizes the continuous mixing of strip rubber by using a double-screw extruder, but the method depends on a continuous powder weighing and mixing system, has high technical difficulty, and does not solve the problem of layering of raw materials with different particle sizes and different densities.

CN201610664108 discloses a continuous rubber mixing process, which comprises a continuous mixing step: adding a part of raw rubber raw materials in the weighed formula and other systems in the formula into an internal mixer for mixing; after mixing for a preset time, directly feeding the rubber material into a counter-rotating double-screw extruder for extrusion; directly feeding the extruded rubber material into a double-roller tablet press for tabletting and forming to obtain pre-dispersed masterbatch; continuous plastication two-stage step: adding the rest of raw rubber raw materials in the formula into a continuous plasticator for plastication to obtain plasticated rubber; three continuous mixing steps: and continuously and quantitatively adding the pre-dispersed master batch and the plasticated rubber into a continuous mixing roll for continuous mixing. The present background art mentions the use of a pre-dispersed masterbatch, but the pre-dispersed masterbatch and the masticated rubber both exist in the form of sheets, which are then compounded using a continuous mixer, which is essentially a series of an internal mixer and a counter-rotating twin-screw extruder, and the compounding process is essentially accomplished by an internal mixer, and the morphology and composition of the pre-dispersed masterbatch mentioned in the art cannot be directly compounded by a twin-screw extruder. At the same time, continuous and quantitative feeding of masticated gum and predispersed masterbatch to the mixer presents difficulties, and the background art does not disclose a solution to this problem.

CN201210441618 relates to a rubber additive, and a sulfur pre-dispersion master batch formula comprises the following components in parts by weight: sulfur powder 80; a base material 16; stearic acid 1; and (3) white oil. The matrix materials used were: ethylene Propylene Diene Monomer (EPDM), ethylene-vinyl acetate copolymer (EVA) and ethylene octene copolymer (POE), wherein the type of the used EPDM is 4045, the content of vinyl acetate in the EVA is 30%, and the type of the POE is 8180. The sulfur pre-dispersion master batch particles are prepared by uniformly dispersing sulfur powder into a carrier and then granulating. The background art mentions the use of pre-dispersed master batches of EVA and sulfoyellow powder, but the technology only uses the EVA as a small amount of adhesive, and does not mention the use of the EVA as a high-fluidity plasticizing phase, and meanwhile, the EVA does not have the function of the high-fluidity plasticizing phase due to the large sulfur filling amount. Meanwhile, the technical scheme has no way of mixing rubber in an extruder.

In summary, the direct use of twin screw extruders for rubber compounding has not been a well established and reliable solution in the prior art, nor has the prior art been able to solve the problems of metering or mixing uniformity. These are also important reasons why the use of twin-screw extruders for compounding rubber is not currently commercially available.

Disclosure of Invention

When the double-screw extruder is used for rubber mixing, the problem of insufficient shearing exists, so that when the traditional rubber formula mode is directly used for mixing by using double screws, the required mixing uniformity is difficult to obtain, particularly a sulfur-containing system, sulfur is often agglomerated in the system, the sufficient shearing effect is not available, and the sulfur is difficult to uniformly disperse; meanwhile, the components are numerous during rubber mixing, and when the rubber is directly added into the twin-screw, accurate metering is difficult, so that the mixing uniformity is further reduced, and massive rubber is more difficult to feed and meter in the twin-screw, and even if the powdered rubber is fed after the auxiliary components are mixed, the problem of layering is also caused due to density and particle size difference, so that the traditional rubber formula mode cannot use the twin-screw for mixing.

On the other hand, the rubber has the problem of scorching after the components are mixed, and the mixed raw materials cannot be stored and transported.

In order to solve the above problems, the present invention provides a method for compounding rubber in a twin-screw extruder, comprising the steps of:

(1) preparing mixed master batch, uniformly mixing the pre-prepared master batch A and the pre-prepared master batch B according to the formula proportion, and preparing the mixed master batch.

(2) And (3) placing the uniformly mixed master batch into a feed hopper of a double-screw extruder, performing extrusion operation, synchronously completing a mixing process through the mixing action of screws, and extruding to obtain the rubber compound.

The master batch A in the step (1) is a pre-dispersed master batch which contains rubber, EVA or other additives but no sulfur and is subjected to uniform mixing and granulation.

The master batch B in the step (1) is pre-dispersed master batch which contains EVA and sulfur or other auxiliary agents and is subjected to uniform granulation.

The temperature of each section of the extruder is set according to the requirement, but the temperature of each section of the extruder is not higher than 110 ℃, so that the rubber in the whole mixing process system is not vulcanized and crosslinked.

The master batch of the invention can be uniformly mixed and granulated by adopting a common granulating method in the prior art, such as single screw extrusion granulation, water ring granulation and the like after banburying.

The invention has the beneficial effects that:

1. by using the method, the rubber can be fully and uniformly mixed by using a double-screw extruder, and the rubber compound is prepared. The double-screw extruder can fully exert the characteristic of forced conveying of the double screws by mixing, and avoid scorching caused by long-time residence of rubber in dead corners of the screws; the double-screw extruder can be used for continuously and automatically mixing rubber, the production efficiency is high, and the labor consumption is low.

2. The invention provides a method for using two granular pre-dispersed master batches as raw materials, which is convenient for feeding and quantifying by an extruder hopper, and the quantitative feeding can be simply and reliably carried out by preparing the mixed master batches from A, B master batches with different proportions.

3. In the method for using the two granular pre-dispersed master batches, the master batch B containing sulfur does not contain rubber and an accelerant, and the two master batches have certain granularity, so that the sulfur, the rubber and the accelerant in the mixed master batch cannot be mixed together, therefore, the mixed master batch prepared in the step (1) can be safely stored for a long time without worrying about the problem of scorching, and can also be safely stored in a hopper with a twin screw possibly having certain temperature. Meanwhile, the problem that the fluidity of the system in a double screw is poor and the mixing effect is poor due to early scorching crosslinking is avoided.

4. The two master batches used in the method provided by the invention both contain EVA which can be plasticized in an extruder, and simultaneously the melting point of the EVA is very low, and the best melting point and fluidity can be obtained by selecting products with different VA contents, so that the two master batches can have good fluidity in a double-screw extruder, and are easy to be fully mixed and dissolved in the double-screw extruder, thereby realizing uniform mixing effect.

5. The method provided by the invention can prevent the problems of layering and uneven or gradient distribution of different additives in the feeding process of various additives with different densities in a double-screw extruder.

Further optimization schemes of the present invention may be:

the first optimization scheme is as follows: according to the method of the invention, the mixed master batch can also consist of master batch A, master batch B and master batch C, wherein the master batch C can be pre-dispersed master batch which contains EVA and other rubber additives or rubber and does not contain sulfur and is uniformly mixed and granulated. The masterbatch C can also be further divided into various masterbatches.

The optimization scheme has the characteristics that the formula can be more flexibly set while the advantages of the original scheme are kept.

And the second optimization scheme is as follows: according to the method of the invention, the content of the vinyl acetate of the EVA in the master batch A is 26% or less; and the EVA content in the master batch B is 35% or more.

The beneficial effect of the optimized scheme is that the EVA in the master batch A enables the material prepared by the method to have better mechanical property, and the EVA in the master batch B has lower melting point and higher melting index, so that the master batch B has better flowing property in a double screw, and the sulfur in the master batch B has better dispersion effect. The two factors act together, so that the dispersion effect of sulfur can be improved when the method is used on the premise of not influencing the performance of the material too much.

And the optimization scheme is three: according to the method of the second optimization scheme, the temperature of each section of the double-screw extruder is 60-90 ℃, and the temperature of each section can be different.

The beneficial effects of this optimization scheme are that under this temperature section, the EVA in the master batch B fully melts, and flow property is good, and the EVA in master batch A is not completely melted, still has certain intensity for the whole melt strength of system is higher, and the shearing force is stronger, is favorable to mixing evenly.

And the optimization scheme is four: the content of sulfur in the B master batch of the method is 30 percent or less of the total amount of the sulfur and the EVA, wherein the optimal content is 16-23 percent.

The optimization scheme has the beneficial effects that when the sulfur content in the B master batch is 30% or less, the agglomeration degree of the sulfur in the EVA is very small, and the low sulfur content in the EVA also enables the EVA to have better flow property, so that a better dispersion effect is realized.

And the optimization scheme is five: the rubber of the invention is composed of one or more of various synthetic rubbers and natural rubbers, various thermoplastic elastomers and mixtures thereof.

The optimization scheme has the beneficial effects that when the method is applied to mixing of different rubbers, the compatibility of the rubber and an EVA system can be increased by adding the structural component unit which is similar to the rubber structure, namely has similar polarity with the rubber or has the same structural component unit with the rubber, so that the mixing effect of the method is better.

And the optimization scheme is six: the rubber in the master batch A in the method provided by the invention is a mixed rubber of natural rubber, solution polymerized styrene-butadiene rubber and SEBS.

The beneficial effects of the optimized scheme are that the SEBS and the solution-polymerized styrene-butadiene rubber jointly form a solubilization system, the SEBS and the solution-polymerized styrene-butadiene rubber contain the same structural unit segment styrene segments, so that the SEBS and the solution-polymerized styrene-butadiene rubber are mutually and completely soluble, meanwhile, the solution-polymerized styrene-butadiene rubber has better compatibility with natural rubber due to no emulsifier residue in the system, the thermoplastic SEBS and the EVA have better compatibility, and the solubilization body formed by the SEBS and the EVA can obviously increase the intersolubility of the natural rubber and the EVA, so that the natural rubber can rapidly form a good dispersion effect with the EVA system during mixing in a double screw, further, sulfur in the EVA can be well dispersed in the natural rubber, and the method disclosed by the invention has an excellent mixing effect when being applied to the natural rubber.

The optimization scheme is seven: the other auxiliary agents in the master batch A in the method of the invention refer to rubber common auxiliary agents, including but not limited to reinforcing agents, fillers, plasticizers, anti-aging agents, accelerators and the like, and peroxide vulcanizing agents can also be added. The master batch B can also be added with common additives in rubber.

The optimization scheme has the beneficial effects that the master batch A can be added with all the commonly used rubber additives, so that various performance requirements of rubber mixing are met; the peroxide vulcanizing agent is added to disperse the mixture into the EVA phase in the mixing process of the method, and the crosslinking of the EVA is synchronously realized in the subsequent vulcanizing process. And common additives are added into the master batch B, so that the dispersion of the common additives in a system is facilitated.

The further scheme is as follows: the method also comprises the following steps of (1) directly extruding the extruded rubber compound into a plunger cylinder with fixed volume; (2) the quantitative mixing rubber in the plunger cylinder is injected into a mould in a flat vulcanizing machine for mould pressing and vulcanization to form a product.

The scheme has the beneficial effects that the advantages of the method for mixing the double-screw extruder are further exerted, one-time completion from mixing to vulcanization is realized, and the labor cost and the working procedures are saved.

The invention also provides a set of equipment of the double-screw extruder for mixing rubber, which consists of the co-rotating double-screw extruder, a plunger barrel at the tail end of the extruder and a flat vulcanizing machine directly connected with the plunger barrel.

Wherein the plunger barrel is linked with the extruder, and the extruder stops extruding when the plunger moves to a specific position.

Detailed Description

The present invention is further illustrated by the following examples.

Embodiment effect evaluation method:

the method for evaluating the uniformity is as follows:

method (1): the rubber mixtures obtained by the methods of examples and comparative examples were placed on an open mill to a thickness of 2mm, and the sheets were pressed once and observed with light. And counting the number of sulfur yellow spots in each 5cm square area, wherein the number of sulfur yellow spots which are not visible to naked eyes is excellent, the number of sulfur yellow spots within three is excellent, the number of sulfur yellow spots within 3-10 is medium, and the number of sulfur yellow spots exceeding 10 is poor.

Method (2): and vulcanizing the mixed rubber material for 50min at 160 ℃, and then testing the tensile strength of 5 dumbbell sample sheets, wherein the difference between the maximum strength and the minimum strength is more than 50%, the difference is 30-50%, the difference is 10-30% and good, and the difference is more than 10% and excellent.

Example 1

The selected master batch A is the following formula, and the preparation method is extrusion granulation after mixing.

EVA，30％VA	20 portions of
		Cis-butadiene rubber 9100	100 portions of
Accelerator TBBS	2 portions of
		Basic zinc carbonate	1 part of

The selected master batch B is the following formula, and the preparation method is extrusion granulation after mixing.

EVA，30％VA	70 portions of
		Sulfur	30 portions of

Mixing the master batch A and the master batch B according to the proportion of 10: 1, mixing the mixture for 5min at 100RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder to be 80 ℃ at each section and the rotating speed to be 80RPM, and carrying out mixing extrusion.

Comparative examples 1 to 1

The diced cis-polybutadiene rubber 9100 is prepared according to the following formula

EVA，30％VA	27 portions of
		Cis-butadiene rubber 9100	100 portions of
Accelerator TBBS	2 portions of
		Basic zinc carbonate	1 part of
Sulfur	3 portions of

Mixing the raw materials in a color mixer at 100RPM for 5min, adding the mixture into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder at 80 ℃ in each section and the rotating speed at 80RPM, and mixing and extruding.

Comparative examples 1 to 2

The formulation of butadiene rubber 9100 using cryogenically ground rubber was as follows

Comparative examples 1 to 3

Cis-butadiene rubber 9100	100 portions of
		Accelerator TBBS	2 portions of
Basic zinc carbonate	1 part of

EVA，30％VA	70 portions of
		Sulfur	30 portions of

Comparative examples 1 to 4

Cis-butadiene rubber 9100	70 portions of
		Sulfur	30 portions of

Comparative examples 1 to 5

EVA，30％VA	20 portions of
		Cis-butadiene rubber 9100	100 portions of
Accelerator TBBS	2 portions of
		Basic zinc carbonate	1 part of
Sulfur	3 portions of

Example 2

EVA，30％VA	70 portions of
		Sulfur	30 portions of

The selected master batch C is the following formula, and the preparation method is extrusion granulation after mixing.

EVA，30％VA	20 portions of
		Accelerant CZ	10 portions of
Anti-aging agent 4010NA	10 portions of

Mixing the master batch A with the master batch B and the master batch C according to the proportion of 10: 1: 2, mixing the mixture for 5min at 120RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder to be 91 ℃ at each section and the rotating speed to be 70RPM, and carrying out mixing extrusion.

Example 3

EVA，26％VA	20 portions of
		Natural rubber 3L	5 portions of
Accelerator TBBS	2 portions of
		White carbon black	5 portions of
Basic zinc carbonate	1 part of

EVA，40％VA	80 portions
		Sulfur	20 portions of

Mixing the master batch A and the master batch B according to the proportion of 12: 1, mixing the mixture for 5min at 90RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder to be 96 ℃ at each section and the rotating speed to be 80RPM, and carrying out mixing extrusion.

Example 4

EVA，10％VA	20 portions of
		Natural rubber 3L	5 portions of
Accelerator TBBS	2 portions of
		White carbon black	5 portions of
Basic zinc carbonate	1 part of

Mixing the master batch A and the master batch B according to the proportion of 12: 1, mixing the mixture for 5min at 90RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder to be 95 ℃ at each section and the rotating speed to be 80RPM, and carrying out mixing extrusion.

Example 5

EVA，40％VA	80 portions
		Sulfur	20 portions of

Mixing the master batch A and the master batch B according to the proportion of 12: 1, mixing the mixture for 5min at 90RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder in four sections, and mixing and extruding the mixture at the rotating speed of 80RPM from the hopper to the machine head direction at 60 ℃, 60 ℃, 70 ℃ and 60 ℃.

Example 6

EVA，40％VA	80 portions
		Sulfur	20 portions of
Accelerant CZ	10 portions of
		Anti-aging agent 4010NA	20 portions of

Mixing the master batch A and the master batch B according to the proportion of 12: 1, mixing the mixture for 5min at 90RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder in four sections, and mixing and extruding the mixture at the rotating speed of 80RPM from the hopper to the head direction at 80 ℃, 90 ℃, 90 ℃ and 80 ℃.

Example 7

EVA，40％VA	80 portions
		Sulfur	20 portions of

Mixing the master batch A and the master batch B according to the proportion of 10: 1, mixing the mixture for 5min at 90RPM by using a color mixer, adding the mixed master batch into a hopper of a double-screw extruder, controlling the temperature of the double-screw extruder in four sections, and mixing and extruding the mixture at the rotating speed of 80RPM from the hopper to the head direction at 60 ℃, 70 ℃, 80 ℃ and 70 ℃.

The implementation effect is as follows:

the method for evaluating the uniformity is as follows:

The implementation effect is as follows:

the method and the optimized scheme provided by the invention are exemplified in the above examples, and it can be seen from comparison with the effect of the comparative example that the method provided by the invention can achieve a good mixing effect by using a twin-screw extruder to mix rubber.

It should also be noted that the above methods are only examples of practical applications of the present invention, and not all implementation methods are only the methods mentioned in the above embodiments, and any solutions having the technical features of the present invention or being available to those skilled in the art through limited experiments are within the scope of the present invention.

Claims

1. A method for compounding rubber by a twin-screw extruder, comprising the steps of:

preparing mixed master batches, namely uniformly mixing the pre-prepared master batch A and the master batch B according to a formula ratio to prepare the mixed master batches;

placing the uniformly mixed master batch into a feed hopper of a double-screw extruder, performing extrusion operation, synchronously completing a mixing process through the mixing action of screws, and extruding to obtain a rubber compound;

the master batch A in the step (1) is a pre-dispersed master batch which contains rubber, EVA or other additives but no sulfur and is subjected to uniform mixing and granulation;

the master batch B in the step (1) is a pre-dispersed master batch which contains EVA and sulfur or other auxiliary agents and is subjected to uniform granulation;

2. The method of claim 1, wherein the EVA content of the masterbatch A is 26% or less; the EVA content in the master batch B is 35% or more.

3. The method of claim 3, wherein the temperature of each section of the twin-screw extruder is 60 to 90 ℃ and the temperature of each section may be different.

4. The B-masterbatch of claim 1 having a sulfur content of 30% or less, preferably 16-23%, of the total amount of sulfur and EVA.

5. The rubber of claim 1 comprised of one or more of various types of synthetic rubber, natural rubber, and various types of thermoplastic elastomers, and mixtures thereof.

6. The rubber in the masterbatch A of claim 1, which is a mixed rubber of natural rubber, solution polymerized styrene-butadiene rubber and SEBS.

7. The master batch A of claim 1, wherein the other auxiliary agents are rubber common auxiliary agents, including but not limited to reinforcing agents, fillers, plasticizers, anti-aging agents, accelerators and the like, and peroxide vulcanizing agents can be added; the master batch B can also be added with common additives in rubber.

8. The method of claims 1-7, wherein the mixed masterbatch is further composed of masterbatch A, masterbatch B and masterbatch C, the masterbatch C is pre-dispersed masterbatch containing EVA and other rubber additives, or rubber and sulfur-free, and uniformly mixed and granulated; the masterbatch C can also be further divided into various masterbatches.

9. The method of claims 1-8, further comprising the subsequent steps of (1) extruding the extruded mix directly into a fixed volume plunger barrel; (2) the quantitative mixing rubber in the plunger cylinder is injected into a mould in a flat vulcanizing machine for mould pressing and vulcanization to form a product.

10. A twin-screw extruder complete equipment for mixing rubber is composed of a co-rotating twin-screw extruder, a plunger barrel at the tail end of the extruder and a flat vulcanizing machine directly connected with the plunger barrel;