CN103044696A - Preparation method of thermoplastic vulcanized rubber - Google Patents

Abstract

The invention discloses a preparation method of thermoplastic vulcanizate, which comprises the following steps in sequence: (1) Preparing rubber and plastic premix: premixing rubber, some plastics, fillers and processing aids by melting, participating in the premixing The weight of the plastic accounts for 20-60% of the total weight of the plastic in the thermoplastic vulcanizate to be prepared; (2) Dynamic vulcanization: add a vulcanizing agent, accelerator or auxiliary crosslinking agent to the premix in step (1), and mix for Dynamic vulcanization; (3) Add the remaining plastic, softening oil and anti-aging agent in the later stage: add the remaining plastic, softening oil and anti-aging agent, and continue to mix evenly to obtain thermoplastic vulcanizate. The weight of the softening oil is 10-30% of the total weight of the plastic. %. The thermoplastic vulcanizate prepared by the invention has the advantages of high fluidity, low hardness and low compression permanent deformation.

Description

A kind of preparation method of thermoplastic vulcanizate

the

technical field

The invention relates to the technical field of vulcanized rubber, in particular to a preparation method of thermoplastic vulcanized rubber.

the

Background technique

Thermoplastic vulcanizate refers to adding rubber and vulcanizing agent to thermoplastic resin. In a mixer with high temperature field and high shear field, the resin and rubber are melt blended, and the rubber is chemically cross-linked in situ at the same time. A new type of elastomer is prepared by forming a stable dispersion system in the resin. It is mainly composed of two parts, one is plastic as the continuous phase, and the other is rubber as the dispersed phase. Usually, rubber needs softening oil or plasticizer to cooperate with it, vulcanizing agent and some auxiliary additives are also essential. In addition, in order to reduce costs or improve certain aspects of performance, some inorganic fillers will also be added. Because thermoplastic vulcanizate not only has the processing convenience of thermoplastics, but also has the high elasticity of thermosetting rubber, excellent comprehensive performance, simple industrial process of molding, greatly shortens the processing cycle and can be recycled and reused, so its products are widely used in various production field and gradually replace traditional rubber.

The traditional preparation method of thermoplastic vulcanizate is: first melt and mix plastic and antioxidant in a high-temperature mixer, then add rubber and mix, then add processing aids, fillers, softening oil and mix evenly, and finally add vulcanizing agent and accelerator. Dynamic vulcanization is carried out while mixing to obtain thermoplastic vulcanizate, which is pelletized after cooling. To a certain extent, dynamic vulcanization technology is not suitable for preparing thermoplastic vulcanizates with low hardness and high fluidity. This is because in order to obtain vulcanized rubber with low hardness, the content of rubber components must be increased. The existence of a large number of vulcanized rubber particles increases the elasticity of the material, but the fluidity decreases significantly, which makes the melt easy to break and difficult to achieve extrusion and injection molding. If the rubber content is reduced, the hardness of the material will increase significantly, that is, the elasticity will decrease. Taking into account the low hardness and high fluidity of thermoplastic vulcanizates is the difficulty in preparing thermoplastic vulcanizates.

The invention patent with the Chinese patent publication number CN1916055A discloses a method for improving the fluidity of thermoplastic vulcanizates, which promotes the degradation of PP in thermoplastic vulcanizates by adding dicumyl peroxide, thereby improving the fluidity of products, although thermoplastic vulcanizates The fluidity of the product is improved, but at the expense of the strength of the product; at the same time, the addition of dicumyl peroxide will consume the antioxidant added in the dynamic vulcanization stage, resulting in a loss of product aging performance. The Chinese invention patent with the publication number CN101696279A discloses a method for preparing a dynamically vulcanized thermoplastic elastomer. The method prepares a reactive one-step material, a vulcanizing agent masterbatch, and an accelerator masterbatch in advance, and then blends the three materials to melt and dynamically Crosslinking to prepare thermoplastic vulcanizate, although it can effectively disperse vulcanizing agent and accelerator, and ensure the shear dispersion of rubber phase, but the preparation process is cumbersome and the hardness of the product is relatively high. The Chinese invention patent with the publication number CN1508170A discloses a preparation method of thermoplastic vulcanizate. In this method, rubber and plastic are premixed first, then rubber masterbatch is prepared, and then dynamic vulcanization is carried out, and oil is added later. Since this method is to add the anti-aging agent in the early stage, it will inhibit the dynamic vulcanization process, and at the same time it cannot absorb the free radicals generated during the dynamic vulcanization process; The full dispersion of other processing aids in the rubber is not conducive to the full vulcanization and shear dispersion of the rubber phase, and cannot guarantee the mechanical properties of the final product.

In summary, the preparation methods of existing thermoplastic vulcanizates need to be further improved.

the

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects in the prior art, and provide a method for preparing thermoplastic vulcanizate, which can produce thermoplastic vulcanizate with high fluidity, low hardness and low compression set.

To achieve the above object, the present invention adopts the following technical solutions:

A kind of preparation method of thermoplastic vulcanizate is characterized in that comprising the following steps in sequence:

(1) Preparation of rubber and plastic premix: melt and premix rubber with some plastics, fillers, and processing aids, and the weight of the plastics involved in the premixing accounts for 20-60% of the total weight of plastics in the thermoplastic vulcanizate to be prepared;

(2) Dynamic vulcanization: add a vulcanizing agent, accelerator or crosslinking assistant to the premix in step (1), and mix for dynamic vulcanization;

(3) Add the remaining plastic, softening oil and anti-aging agent in the later stage: Add the remaining plastic, softening oil and anti-aging agent, and continue to mix evenly to obtain thermoplastic vulcanizate. The weight of the softening oil is 10-30% of the total weight of the plastic.

Preferably, the melting and premixing temperature in step (1) is 180-220° C., and the dynamic vulcanization time in step (2) is 5-10 minutes.

The three steps of the preparation method of the present invention can be continuously carried out on internal mixers, open mills, and double-stage twin-screw extruders, avoiding the cumbersome preparation process brought about by dividing the masterbatch or masterbatch. Since the stroke of a single twin-screw extruder is short, it is relatively difficult to ensure a long dynamic vulcanization time. Therefore, the preparation method of the present invention is preferably carried out in a double-stage twin-screw extruder. The upper stage of the double-stage twin-screw extruder is a single-screw extruder, which can run at high speed to convey molten and compacted homogeneous materials; the lower stage of the two-stage twin-screw extruder is a twin-screw extruder, which can Process requirements for long-term dynamic vulcanization. Specifically: in the upper stage of the two-stage extruder, rubber and some plastics, fillers, and auxiliary agents are melted and premixed, and vulcanizing agents, accelerators or auxiliary crosslinking agents are added in the middle; in the extrusion section of the lower stage Carry out dynamic cross-linking; finally add the remaining plastic and anti-aging agent in the middle and back of the lower stage, extrude and water-cool granulate to obtain thermoplastic vulcanizate.

The formula used in the present invention is the formula of conventional thermoplastic vulcanizate in the prior art, and concrete various components are as follows:

The rubber is chloroprene rubber, natural rubber, trans isoprene rubber, EPDM rubber, butadiene rubber, ethylene-vinyl acetate copolymer, chlorinated polyethylene rubber, acrylate rubber, nitrile rubber, styrene-butadiene rubber A mixture of one or more than two types of rubber.

The plastic is one or both of polyethylene, polystyrene, polyvinyl chloride, polypropylene, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer, polymethyl methacrylate A mixture of the above.

The filler is one or a mixture of two or more of white carbon black, carbon black, clay, silica and kaolin.

The vulcanizing agent is organic peroxide or sulfur or phenolic resin.

The organic peroxide is dibenzoyl peroxide, 1,1-bis(tert-amyl peroxy)cyclohexane, tert-butyl peroxybenzoate, 1,4-bis(tert-butyl peroxydiisopropyl)benzene, 1,3-bis(tert-butylperoxydiisopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane alkane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, ethyl-3,3-bis(tert-butylperoxy)butyrate, ethyl- 3,3-Di(tert-amylperoxy)butyrate is one or more than two kinds of mixture.

The accelerator is one or both of dithiocarbamates, xanthates, guanidines, thioureas, sulfenamides, thiurams, aldehydes, amines, and metal halides. A mixture of the above.

The auxiliary crosslinking agent is triallyl cyanurate, triallyl isocyanurate, N, N-phenyl bismaleimide, ethylene glycol dimethacrylate, vinyl dimethacrylate One or two or more of ethylene glycol ester, trimethylolpropyl trimethacrylate, trimethylolpropyl triacrylate and allyl methacrylate are mixed.

The anti-aging agent is anti-aging agent A, anti-aging agent D, anti-aging agent 2246, anti-aging agent 4010, antioxidant 264, antioxidant 1010, antioxidant 1076, antioxidant 245, light stabilizer UV-9, light stabilizer UV-327 , Light stabilizer UV-328, light stabilizer UV-329, light stabilizer UV-531 one or more than two kinds of mixture.

The softening oil is one or a mixture of two or more of naphthenic oil, paraffin oil and vaseline.

The processing aid is stearic acid or polyethylene wax or a mixture of the above two.

The pre-mixing technology of rubber and plastic can make the rubber and some plastics mix very uniformly. After further adding plastics, all the plastics and rubber will form a uniform shape in a short time. Because the process time of dynamic vulcanization is short, the rubber is dispersed while being vulcanized in the traditional preparation method, resulting in that the rubber and plastic cannot be mixed evenly; Migration in the plastic phase affects product performance. Part of the plastic and rubber premixing avoids the above disadvantages, making the rubber well dispersed before dynamic vulcanization, and also creates conditions for the phase reversal of rubber and plastic. Good dispersion of rubber particles also provides the necessary conditions for the high fluidity of the vulcanizate.

The batch adding technology of plastic is conducive to the full dispersion of vulcanizing agent and accelerator in rubber, so as to ensure the full vulcanization and shear dispersion of rubber phase. In the traditional preparation method, various additives inevitably move into the plastic phase, reducing the full contact with the rubber phase; at the same time, various organic peroxides can also cause degradation of the plastic. Adding plastics in batches can reduce the above behavior; at the same time, adding plastics later can further shear and refine the rubber phase and disperse in the plastic phase, thereby improving the fluidity of thermoplastic vulcanizates.

Late oil filling refers to the addition of softening oil equivalent to 10-30% of the plastic content after the dynamic vulcanization is completed. A small part of this part of the oil will penetrate into the rubber particles, but most of it will remain in the plastic phase. The addition of softening oil can plasticize the vulcanizate with a small amount, thereby significantly reducing the hardness and compression set of the vulcanizate, and improving the fluidity.

Adding anti-aging agent in the later stage can avoid the inhibition of these thermal oxygen or light stabilizers on the dynamic vulcanization process, and prevent these additives from being consumed in advance during processing; Absorption, avoiding the degradation of plastics added later, thus ensuring the mechanical properties of the final product.

In summary, the beneficial effects of the present invention are:

1. The technology of adding plastics in batches, premixing some plastics and rubbers, oil filling and adding anti-aging agents in the later stage can effectively increase the vulcanization and shear dispersion of the rubber phase, effectively improve the fluidity of thermoplastic vulcanizates, and prepare products at the same time The hardness is low, and the compression permanent deformation is small. The specific performance parameters are shown in Table 1;

2. The preparation method of the present invention can be continuously produced on internal mixers, open mills, and double-stage twin-screw extruders, and has the advantages of wide application range of equipment, simple preparation process, and low production cost.

the

Detailed ways

The present invention will be described in further detail below through specific implementation examples. The following processing aids are selected from stearic acid or polyvinyl vinegar, and the anti-aging agent is selected from antioxidant 1010 or antioxidant 168 or light stabilizer UV-9 or light stabilizer UV-327.

Example 1

A kind of preparation method of thermoplastic vulcanizate, it comprises the following steps in sequence:

(1) Preparation of rubber and plastic premix: 60 parts of ethylene propylene diene monomer (EPDM), 20 parts of polypropylene (PP), 5 parts of filler white carbon black and 0.5 parts of processing aids were put into 180 ℃ double-roll milling In the machine, mix evenly, make a triangular bag twice, and obtain a rubber-plastic premix.

(2) Dynamic vulcanization: Add 2 parts of organic peroxide dicumyl peroxide (DCP) and 1 part of auxiliary crosslinking agent triallyl cyanurate (TAIC) to the rubber and plastic premix, mix well and Carry out dynamic vulcanization, and the dynamic vulcanization time is 5-10 minutes.

(3) After the dynamic vulcanization is completed, add 20 parts of PP, 20 parts of naphthenic oil, and 1 part of anti-aging agent, mix well, and discharge to obtain EPDM rubber/polypropylene (EPDM/polypropylene) with a rubber-plastic ratio of 60/40 PP) thermoplastic vulcanizate.

Example 2

A kind of preparation method of thermoplastic vulcanizate, it comprises the following steps in sequence:

(1) Preparation of rubber and plastic premix: put 70 parts of styrene-butadiene rubber (SBR), 15 parts of polypropylene (PP), 10 parts of filler white carbon black and 0.5 parts of processing aid into the internal mixer at 200 °C, Mix evenly to obtain a rubber-plastic premix.

(2) Dynamic vulcanization: Add 3 parts of sulfur and 1 part of accelerator thiocarbamoylsulfenamide into the rubber and plastic premix, mix well and perform dynamic vulcanization. The dynamic vulcanization time is 5-10 minutes.

(3) After the dynamic vulcanization is completed, add 15 parts of PP, 15 parts of white oil, and 1 part of anti-aging agent, mix evenly, and discharge materials to obtain a thermoplastic rubber/polypropylene (SBR/PP) with a rubber-plastic ratio of 70/30. vulcanized rubber.

Example 3

A kind of preparation method of thermoplastic vulcanizate, it comprises the following steps in sequence:

(1) Preparation of rubber and plastic premix: Put 65 parts of ethylene propylene diene monomer (EPDM), 20 parts of polypropylene (PP), 5 parts of filler silica and 0.5 parts of processing aid into the double-stage twin-screw The first feeding port on the upper stage of the extruder is used for the pre-mixing of rubber and plastic at the upper screw. The temperature of each section of the two-stage twin-screw extruder is set at 180-220°C.

(2) Mix 2 parts of organic peroxide 2,5-dimethyl-2,5-(di-tert-butylperoxy)hexane and 1 part of co-crosslinking agent triallyl cyanurate (TAIC) in bis The second feeding port of the upper stage of the cascaded twin-screw extruder is added, and the dynamic vulcanization is carried out at the lower stage of the screw.

(3) Add 15 parts of PP, 10 parts of naphthenic oil, and 1 part of anti-aging agent to the middle and rear strokes of the lower screw of the double-stage twin-screw extruder, mix evenly, extrude, and water-cool granulate to obtain EPDM/PP thermoplastic vulcanizate with a rubber-to-plastic ratio of 65/35.

Example 4

A kind of preparation method of thermoplastic vulcanizate, it comprises the following steps in sequence:

(1) Preparation of rubber and plastic premixes: 65 parts of butadiene rubber (BR), 15 parts of polypropylene (PP), 15 parts of filler carbon black and 0.5 parts of processing aids were put into a 180°C double-roll mill, Mix evenly, pack into a triangular bag twice to obtain a rubber-plastic premix.

(2) Add the 4 vulcanizing agent brominated phenolic resin into the rubber plastic premix, mix well and carry out

Dynamic vulcanization. The dynamic vulcanization time is 5-10 minutes.

(3) After the dynamic vulcanization is completed, add 20 parts of PP, 20 parts of naphthenic oil, and 1 part of anti-aging agent, mix well, and discharge to obtain butadiene rubber/polypropylene (BR/PP) with a rubber-plastic ratio of 65/35 Thermoplastic vulcanizate.

Comparative example 1:

Using traditional technology to prepare EPDM/PP thermoplastic vulcanizate with rubber-to-plastic ratio of 60/40, the specific operation process is as follows:

Mix 60 parts of EPDM, 40 parts of polypropylene (PP), 5 parts of filler silica and 0.5 parts of processing aids, 2 parts of machine peroxide dicumyl peroxide (DCP) and 1 Add 1 part of auxiliary crosslinking agent triallyl cyanurate (TAIC), 20 parts of naphthenic oil, and 1 part of anti-aging agent to a 180°C double-roll mill, mix evenly, make triangular bags twice, and discharge to obtain rubber and plastic EPDM/PP thermoplastic vulcanizate with a ratio of 60/40.

Comparative example 2:

The styrene-butadiene rubber/polypropylene (BR/PP) thermoplastic vulcanizate with a rubber-to-plastic ratio of 70/30 was prepared by traditional technology, and the specific operation process was as follows:

70 parts of styrene-butadiene rubber (BR), 30 parts of polypropylene (PP), 10 parts of filler white carbon black and 0.5 parts of processing aids, 3 parts of sulfur and 1 part of accelerator thiocarbamoylsulfenamide, 15 parts Add white oil and 1 part of anti-aging agent to the internal mixer at 180°C, mix evenly, make triangular bags twice, and discharge to obtain thermoplastic vulcanization of styrene-butadiene rubber/polypropylene (BR/PP) with a rubber-to-plastic ratio of 70/30 glue.

Comparative example 3:

Using traditional technology to prepare EPDM/PP thermoplastic vulcanizate with rubber-to-plastic ratio of 70/30, the specific operation process is as follows:

70 parts of EPDM, 30 parts of polypropylene (PP), 5 parts of filler white carbon black and 0.5 parts of processing aids, 2 parts of organic peroxide 2,5-dimethyl-2,5 -(Di-tert-butylperoxy)hexane and 1 part of triallyl cyanurate (TAIC), 10 parts of naphthenic oil, 1 part of anti-aging agent, mix well and add to ordinary twin-screw extruder . The extruder temperature was set at 180-190°C. Extrude, water-cooled and granulate to obtain EPDM/PP thermoplastic vulcanizate with a rubber-to-plastic ratio of 70/30. Due to the large proportion of rubber, the mixing is not sufficient, the strips are often broken during the extrusion process, and the surface of the extruded product is rough.

The products of Examples 1, 2, and 3 were selected as measurement objects, and part of the materials were pressed into tablets to cut samples, and performance tests were carried out according to corresponding national standards. Simultaneously compare it with the performance of the products of Comparative Examples 1, 2, and 3. The specific results are shown in Table 1.

Table 1:

the Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 3 Hardness (Shore D) 40 30 36 58 45 51 Tensile strength MPa 7.2 6.5 6.8 7.0 6.6 6.7 Elongation at break % 330 400 385 315 386 354 Tensile set % 15 13 14 29 26 twenty four Compression set % 27 33 30 42 47 45 The melt flow rate 7.2 6.4 5.7 1.3 2.1 0.9

The condition for measuring compression set is 70°C×22h, and the test condition for melt flow rate is g/10min (230°C, 5Kg). As can be seen from Table 1, compared with Comparative Example 1 and 2, its hardness, tensile set, and compression set are less than Comparative Example 1 and 2; and tensile strength and melt flow rate are higher than Comparative Example 1 ,2. The situation of embodiment 3 is the same as that of comparative example 3. Simultaneously, the extrusion situation of embodiment 3 is stable, easy to draw, and the product surface is smooth. In Comparative Example 3, the extrusion was easy to break, and the surface of the product was rough. In general, the comparison of the above conditions shows that the vulcanizate prepared by the preparation method of the thermoplastic vulcanizate of the present invention has high fluidity, low hardness, and low compression set, so its overall performance is better than that prepared by the traditional process. thermoplastic vulcanizate.

The above-mentioned embodiments are only preferred implementation modes of the present invention, and cannot be used to limit the protection scope of the present invention. Any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention all belong to the present invention protected range.

Claims (10)

1. the preparation method of a thermoplastic sulfurized rubber is characterized in that may further comprise the steps in turn:

(1) preparation rubber and plastics Preblend: with rubber and partly plastic, filler, processing aid melting premix, the weight that participates in the plastics of premix accounts for the 20-60% of plastics gross weight in the thermoplastic sulfurized rubber to be prepared;

(2) dynamic vulcanization: in the Preblend of step (1), add vulcanizing agent, promotor or additional crosslinker, be mixed into the Mobile state sulfuration;

(3) later stage adds leftover and plastic, softening oil and anti-aging agent: add remaining plastics, softening oil and anti-aging agent, continue to mix, namely obtain thermoplastic sulfurized rubber, the weight of softening oil is the 10-30% of plastics gross weight.

2. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1 is characterized in that: the temperature of melting premix is 180-220 ℃ in the step (1), and the dynamic vulcanization time is 5-10min in the step (2).

3. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: the method is to carry out in Banbury mixer, mill or two steps type twin screw extruder; The concrete grammar that carries out in the two steps type twin screw extruder is, add rubber and partly plastic, filler, assistant engineer's auxiliary agent melting premix on the upper rank of two steps type twin screw extruder, add in the middle vulcanizing agent, promotor or additional crosslinker, crosslinked at the enterprising Mobile state of extruding zone on the lower rank of two steps type twin screw extruder; Postmedian on lower rank adds leftover and plastic and anti-aging agent at last, extrudes rear water-cooled granulation, obtains thermoplastic sulfurized rubber.

4. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: described rubber is one or more mixing in chloroprene rubber, natural rubber, trans-isoprene, terpolymer EP rubber, cis-1,4-polybutadiene rubber, ethylene-vinyl acetate copolymer, chlorinated polyethylene rubber, acrylic elastomer, paracril, the styrene-butadiene rubber(SBR).

5. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1 is characterized in that: described plastics be polyethylene, polystyrene, polyvinyl chloride, polypropylene, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer, polymethylmethacrylate, in one or more mixing.

6. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: described filler is one or more mixing in White Carbon black, carbon black, potter's clay, tripoli, the kaolin.

7. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: described vulcanizing agent is organo-peroxide or Sulfur or resol.

8. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: described promotor is one or more mixing in dithiocarbamate(s), xanthogenic acid salt, guanidine class, Thiourea, sulfenamide, thiurams, aldehyde amines, the metal halide class; Described additional crosslinker is triallyl cyanurate, triallyl isocyanurate, N, one or more mixing in N-phenyl-bismaleimide, ethyleneglycol dimethyacrylate, dimethacrylate vinyl glycol ester, trimethylammonium vinylformic acid trishydroxymethyl propyl ester, three vinylformic acid trishydroxymethyl propyl ester, the allyl methacrylate(AMA).

9. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: described anti-aging agent is one or more mixing among antioxidant A, antioxidant D, antioxidant 2246, antioxidant 4010, antioxidant 264, antioxidant 1010, antioxidant 1076, antioxidant 245, photostabilizer UV-9, photostabilizer UV-327, photostabilizer UV-328, photostabilizer UV-329, the photostabilizer UV-531.

10. the preparation method of thermoplastic sulfurized rubber as claimed in claim 1, it is characterized in that: described softening oil is one or more mixing in naphthenic oil, paraffin oil, the Vaseline.