CN107446247B

CN107446247B - Mixed pre-dispersed masterbatch composition and preparation method thereof

Info

Publication number: CN107446247B
Application number: CN201710785446.3A
Authority: CN
Inventors: 连加松
Original assignee: Jiangsu Chemical Ltd By Share Ltd
Current assignee: Jiangsu Chemical Ltd By Share Ltd
Priority date: 2017-09-04
Filing date: 2017-09-04
Publication date: 2020-01-21
Anticipated expiration: 2037-09-04
Also published as: CN107446247A

Abstract

The invention provides a pre-dispersed masterbatch composition comprising a first premix and a second premix, wherein the first premix comprises a rubber substrate, an EVA resin, a dispersant, a processing oil, and optionally other processing aids, the second premix comprises two or more vulcanization accelerators, the first premix comprising 10 to 35 wt.% of the composition and the second premix comprising 65 to 90 wt.% of the composition, based on 100 wt.% of the masterbatch composition, wherein the two or more vulcanization accelerators comprise one or more dithiocarbamate accelerators and one or more thiuram accelerators. The present invention also provides a vulcanization accelerator composition comprising zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide. The invention also provides a method for preparing the pre-dispersed masterbatch particle composition.

Description

Mixed pre-dispersed masterbatch composition and preparation method thereof

Technical Field

The invention relates to a masterbatch particle composition pre-dispersed with a plurality of rubber additives, in particular vulcanization accelerators, and a preparation method thereof. The master rubber particle is particularly suitable for vulcanization molding of rubber sealing rings, especially rubber sealing rings.

Background

With the development of rubber additive applications, various problems of conventional rubber additives during processing and application are gradually exposed. For example, in the case of organic powder assistant powder, the use of an easily-adhesive roller reduces the use efficiency and the production efficiency, dust flies to cause pollution and harm to the body of an operator, and the dispersion time is long and the dispersion efficiency is low.

Although processing of the split aids into masterbatch pellets can solve problems such as dust contamination, existing pre-dispersed masterbatch pellets still have a number of disadvantages. For example, various additives are inconvenient to weigh, the pre-dispersed product with a single component is easy to have poor dispersion, short scorching time and low processing danger, the vulcanization speed is slow, and the processing period is long and the preparation is complex in the early stage and low in efficiency.

The mixed pre-dispersed master batch particles for the sealing ring rubber have more targeted requirements on rubber additives, such as high elasticity and good air tightness required by the sealing ring.

In order to solve the above problems, it is desirable to provide a rubber auxiliary composition which is less in environmental pollution, convenient to store and use, and improves the properties of a seal ring rubber, and a related preparation method.

Disclosure of Invention

Accordingly, the present invention provides in a first aspect a pre-dispersed masterbatch composition comprising a first premix and a second premix, wherein the first premix comprises a rubber substrate, an EVA resin, a dispersant, a processing oil and optionally further processing aids, the second premix comprises two or more vulcanization accelerators, the first premix comprising from 10 to 35 wt% of the composition, the second premix comprising from 65 to 90 wt% of the composition, based on 100 wt% of the masterbatch composition,

wherein the two or more vulcanization accelerators comprise one or more dithiocarbamate accelerators and one or more thiuram accelerators.

The dithiocarbamate accelerator may be selected from one or more of zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate and zinc ethylphenyldithiocarbamate. In a preferred pre-dispersed masterbatch composition according to the invention, the dithiocarbamate accelerator is a mixture of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate and zinc diethyldithiocarbamate.

The thiuram accelerators may be selected from one or more of dipentamethylenethiuram tetrasulfide, tetrabenzylthiuram disulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dimethyldiphenylthiuram disulfide, bis (1, 5-pentamethylene) thiuram tetrasulfide, and tetramethylthiuram tetrasulfide. In a preferred pre-dispersed masterbatch composition according to the invention, the thiuram accelerator is dipentamethylenethiuram tetrasulfide.

In a further preferred embodiment, the second premix is a mixture of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide. Preferably, the weight ratio of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide is 0.5-1: 1-2: 1: 1.5.

The masterbatch composition according to the invention, in the first premix, the respective weights of the substances are as follows:

	weight percent (%)
		Rubber matrix	30 to 70, preferably 40 to 60
Processing oil	15 to 40, preferably 18 to 25
		Dispersing agent	7 to 17, preferably 10 to 15
EVA resin	5 to 20, preferably 10 to 17,

the sum of the percentages by weight of the above substances in the first premix does not exceed 100%.

In a more preferred pre-dispersed masterbatch composition, it comprises, based on 100% by weight of the composition:

a)15-35 wt% of a first pre-mix comprising, in parts by weight,

50 to 70 parts by weight of a rubber base,

20-30 parts by weight of processing oil,

10 to 20 parts by weight of a dispersant, and

10-20 parts by weight of an EVA resin;

b)65 to 85 wt% of a second premix of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide in a weight ratio of 0.5 to 1:1 to 2:1: 1.5.

In the pre-dispersed masterbatch composition according to the invention, the rubber substrate is selected from: ethylene propylene diene monomer, nitrile rubber, styrene butadiene rubber, acrylate rubber, epichlorohydrin rubber or chloroprene rubber, in particular ethylene propylene diene monomer.

In the pre-dispersed masterbatch composition according to the invention, the dispersing agent is selected from C12-C18 fatty acids and polyethylene glycols. The C12-C18 fatty acid is preferably stearic acid.

In the pre-dispersed masterbatch composition according to the invention, the processing oil is selected from aromatic, naphthenic, paraffinic or fatty oils.

In the pre-dispersed masterbatch composition according to the present invention, the processing aid may be selected from stabilizers, flame retardants, lubricants, antistatic agents, coupling agents, fillers, foaming agents, colorants, mold release agents, brighteners, or combinations thereof.

In a second aspect, the present invention provides a pre-dispersed masterbatch composition comprising a rubber substrate, an EVA resin, a dispersant, a processing oil, zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide, and optionally other processing aids.

In a third aspect, the present invention provides a vulcanization accelerator composition comprising zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide. The vulcanization accelerator composition is particularly suitable for use in sealing rubbers. Preferably, the weight ratio of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide is 0.5-1: 1-2: 1: 1.5.

The invention also provides a preparation method of the pre-dispersed masterbatch particles in the fourth aspect, which comprises the following steps:

fully mixing a rubber substrate, EVA resin, a dispersing agent, processing oil and other optional processing aids to obtain a first premix;

thoroughly mixing two or more vulcanization accelerators to obtain a second premix,

uniformly mixing the first premix and the second premix, extruding and granulating to obtain solid pre-dispersed masterbatch particles,

wherein the first premix accounts for 10-35 wt% and the second premix accounts for 65-90 wt% of the total amount of the masterbatch particles of 100 wt%,

wherein the vulcanization accelerator comprises one or more dithiocarbamate type accelerators and one or more thiuram type accelerators.

In a preferred embodiment, the first and second premixes are mixed under a pressure of 0.5-0.6MPa, at a high shear at a speed of 50-110 r/min, and gradually warmed to 60-65 ℃.

The pre-dispersed masterbatch composition according to the present invention may be used in rubber for seal rings. The master rubber particles can promote the stable and uniform generation of cross-linking bonds in the rubber vulcanization process, and avoid the problems of nonuniform formation, poor air tightness and the like of the vulcanization bonds caused by insufficient dispersion of a rubber accelerator, so that the prepared sealing ring can meet the requirements of high elasticity and high air tightness.

Detailed Description

In the process of adding the rubber auxiliary directly or separately to the rubber, the respective rubber auxiliaries are too dispersed in the rubber to interact with each other. In order to allow the various rubber aids such as vulcanization accelerators added to be well mixed, contacted and synergized, the inventors first pre-mixed the various rubber aids in the gum base and made the master batch (composition). The pre-dispersed masterbatch composition according to the present invention is prepared by mixing a specific rubber auxiliary (i.e., the second premix) with a specific base (the first premix) to prepare a crumb, thereby conveniently providing each rubber auxiliary to the rubber for a gasket, and the resulting gasket is also provided with better properties such as better airtightness and higher elasticity.

According to the present invention there is first provided a pre-dispersed masterbatch composition comprising a first premix and a second premix. Including in the first premix a rubber substrate, an EVA resin, a dispersant, a processing oil, and optionally other processing aids; a vulcanization accelerator, which is a mixture of a dithiocarbamate vulcanization accelerator and a thiuram-type vulcanization accelerator, is included in the second premix.

It should be understood that while the description of "first premix" and "second premix" is used herein with respect to the pre-dispersed masterbatch composition, this is for descriptive convenience only, and the ingredients of the first premix are uniformly dispersed and thoroughly mixed in the masterbatch composition with the ingredients of the second premix. Also, the pre-dispersed masterbatch particles according to the present invention are solid at normal temperature, and thus are very convenient in storage and transportation.

First premix

The first premix comprised by the pre-dispersed masterbatch composition according to the invention may be prepared by mixing in a separate step. The rubber substrate, EVA resin, dispersant, processing oil are included in the first premix, and other processing aids may also be added as needed for processing and final properties. It will be appreciated that this first premix is the matrix. The first premix comprises 10 to 35 wt%, preferably 15 to 35 wt%, more preferably 15 to 30 wt% based on the pre-dispersed masterbatch composition.

Rubber substrate

The rubber substrate of the first premix needs to be compatible with the other ingredients used in the pre-dispersed masterbatch, in particular with the rubber of the end application of the pre-dispersed masterbatch. Rubber substrates which can be used in the present invention are those rubbers which are normally used as sealing materials, although other uses are not excluded. Preferably, the rubber substrate may be selected from at least one of the following rubbers: ethylene propylene diene monomer, nitrile rubber, styrene butadiene rubber, acrylate rubber, epichlorohydrin rubber or chloroprene rubber. In a particularly preferred embodiment, the rubber substrate is ethylene propylene diene monomer.

The rubber substrate may be one kind of rubber, or may be a combination of two or more kinds of rubbers.

The content of the rubber base material in the first premix may be 30 to 70% by weight, preferably 40 to 60% by weight.

EVA resin

In addition, to obtain a pelletized composition, an ethylene vinyl acetate copolymer resin, i.e., an EVA resin, is also introduced into the first premix. Foamed grade EVA resins are preferred for use in the present invention. Preferred is an EVA resin with a VA content of 9-33%. More preferably, the melting point of the EVA resin is 60-100 ℃.

One EVA resin may be used in the first pre-mix, or a combination of two or more EVA resins may be used.

The amount of the EVA resin in the first premix is 5 to 20 wt%, preferably 10 to 17 wt%.

Dispersing agent

The dispersants used in the pre-dispersed masterbatch composition of the present invention can increase the activity of the adjuvants, particularly the vulcanization accelerators, allowing them to perform their full function, and in some cases even allow the amount of adjuvant to be reduced appropriately. The dispersant used in the present invention is preferably an organic dispersant, and more preferably a fatty acid and a polyhydric alcohol. The fatty acid is preferably a C12-C18 saturated or unsaturated fatty acid, most preferably stearic acid. The polyol is preferably polyethylene glycol.

The content of the (organic) dispersant in the first premix is 7 to 17% by weight, preferably 10 to 15% by weight.

Processing oil

To obtain the pre-dispersed masterbatch particles of the present invention, it is generally necessary to use a processing oil. The processing oil used in the present invention may be any of various oils that function to disperse, demold, and/or lubricate, including but not limited to aromatic oils, naphthenic oils, paraffinic oils, fatty oils. The process oil used in the present invention is preferably a naphthenic oil.

The amount of process oil in the first premix is 15 to 40 wt%, preferably 18 to 25 wt%.

Other processing aids

Other processing aids may also be included in the first premix to improve or achieve desired properties. Other processing aids include, but are not limited to: one or more of stabilizers, flame retardants, lubricants, antistatic agents, coupling agents, fillers such as inorganic fillers, foaming agents, colorants, mold release agents, and brighteners. The amount of other processing aids can be added in appropriate amounts according to actual needs.

For convenience of processing proportion, each component can also be expressed by weight.

In a further preferred embodiment, the first premix may comprise, expressed in parts by weight:

50-70 parts by weight of a rubber base material;

10 to 20 parts by weight of a processing oil, in particular a naphthenic oil;

10 to 20 parts by weight of a dispersant, in particular stearic acid; and

20-30 parts by weight of EVA resin.

Second premix

The second premix comprised by the pre-dispersed masterbatch composition according to the invention may also be prepared by mixing in a separate step. According to the invention, the second premix is premixed with two or more rubber auxiliaries, in particular vulcanization accelerators. It is understood that the second premix is the rubber auxiliary premix. The second premix comprises 65 to 90 wt%, preferably 65 to 85 wt%, more preferably 70 to 85 wt% based on the pre-dispersed masterbatch composition.

According to the invention, the two or more vulcanization accelerators comprise or consist of a combination of one or more dithiocarbamate accelerators (dithiocarbamate accelerators) and one or more thiuram accelerators (thiuram sacccelerators). That is, one or more dithiocarbamate accelerators and one or more thiuram accelerators are included in or consist of the second premix.

Dithiocarbamate accelerators

Dithiocarbamates used as vulcanization accelerators are generally obtained by reacting carbon disulfide, a secondary amine and an organic or inorganic base, and have the general structural formula:

wherein R, R' independently of each other may be methyl, ethyl, butyl, phenyl, etc.; m is a metal ion or ammonium ion selected from Na, K, Zn, Pb, Ca, Bi, Ni.

Dithiocarbamates are acidic accelerators, also known as superaccelerators, with high activity. Dithiocarbamate accelerators are commonly used for fast curing and low temperature curing of articles. Wherein, ammonium dithiocarbamate, sodium and potassium are water-soluble accelerators and are mainly used as vulcanization accelerators of the rubber and dairy products; the zinc dithiocarbamate has lower promotion activity than ammonium salt, has certain operation safety in dry glue sizing materials, has stronger activation effect on ammonium dithiocarbamate, sodium and potassium promoters in thiazoles, thiurams and latex, and is also the most commonly used variety of the dithiocarbamate promoters.

Potassium, sodium, ammonium, or zinc salts of dithiocarbamic acid can be used in the present invention.

In some embodiments, zinc dithiocarbamate accelerators are preferred. Examples of zinc dithiocarbamate accelerators include, but are not limited to: zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, zinc ethylphenyldithiocarbamate.

According to the present invention, only one kind of the above-mentioned dithiocarbamate may be used, or two or more kinds of the above-mentioned dithiocarbamate may be used in combination. For example, in some embodiments, two, three, four, five or six different dithiocarbamate accelerators are used in combination.

In some preferred embodiments, three different zinc dithiocarbamate accelerators are used in combination. In some more preferred embodiments, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate and zinc dibutyldithiocarbamate are used in combination in the first premix. The zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate and zinc diethyldithiocarbamate are preferably used in a weight ratio of (0.5-1): 1-2): 1.

The sum of the dithiocarbamate accelerators in the second premix may be 50 to 85 wt%, preferably 60 to 75 wt%.

Thiuram accelerators

Thiuram accelerators are also a common class of vulcanization accelerators and have the general structural formula:

in the formula: r, R' are independently selected from alkyl, aryl, cycloalkyl, etc.; x is 1-6.

Thiuram accelerators include thiuram monosulfide, thiuram disulfide and thiuram polysulfide. The accelerator belongs to an acidic super accelerator, has activity between that of dithiocarbamate and thiazole accelerator, is generally used as a second accelerator, and can improve the vulcanization speed and the vulcanization degree of thiazole and sulfenamide accelerators. Thiuram disulfides and polysulfides release active sulfur at standard vulcanization temperatures and are useful as sulfur donors in sulfur-free vulcanization systems.

Exemplary thiuram accelerators are:

in the second premix, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), bis (1, 5-pentamethylene) thiuram tetrasulfide (DPTT), tetramethylthiuram tetrasulfide (TMTT), dimethyldiphenylthiuram disulfide (DDTD), dipentamethylenethiuram disulfide, tetrabenzylthiuram disulfide, and the like can be used.

According to the present invention, one kind of the thiuram-based accelerator may be used, or two or more kinds of the thiuram-based accelerators may be used in combination.

The thiuram type accelerator may be present in the second premix in an amount of 15 to 50 wt%, preferably 25 to 40 wt%.

During the course of the studies on the composition of the predispersed masterbatch, the inventors have also surprisingly found that the use of a specific combination of a dithiocarbamate accelerator and a thiuram accelerator as a rubber aid (i.e. a second premix) for vulcanizing rubber, allows good adaptation to the performance requirements of the sealing rubber, in particular to the requirements in terms of gas tightness and elasticity. In a particularly preferred embodiment, a mixture (second premix) of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, dipentamethylenethiuram tetrasulfide, mixed in a mass ratio of (0.5-1): 1-2): 1:1.5 is preferably used.

Preparation method

The pre-dispersed masterbatch composition according to the invention can be prepared as follows:

1. preparation of the first premix preparation

In this step, the rubber substrate, EVA resin, dispersant, processing oil and optionally other processing aids are thoroughly mixed. For example, the rubber substrate, the EVA resin, the dispersant, the processing oil, and optionally other processing aids are separately charged into an internal mixer (also referred to simply as an internal mixer) in a ratio. Kneading, wherein the mixture is kneaded at a temperature of 85 to 115 ℃ for 10 to 20min, thereby obtaining a first premix;

2. preparation of the second premix

In this step, the required vulcanization accelerator is charged into a mixer in a ratio and sufficiently mixed. The accelerator is usually in powder form.

It will be appreciated that the preparation of the first and second premixes described above is not required to be sequential, and may be performed simultaneously.

3. Preparation of predispersed masterbatch particles (composition)

Mixing the first premix and the second premix according to the proportion. Appropriate amounts of processing oil and processing aids may also be added in this step as desired. For example, the components are added into an internal mixer according to the proportion, fully kneaded, mixed for 5-15 min at the temperature of 50-75 ℃, discharged and put into an extruder, and extruded and granulated to obtain the finished product. Advantageously, the mixing of the first and second premixes is carried out under a pressure of 0.5-0.6MPa, a high shear at a speed of 50-110 r/min and a gradual temperature rise to 60-65 ℃.

The rubber auxiliary agents are pre-dispersed by using a crushing and stirring device such as an internal mixer, and then the pre-dispersed rubber auxiliary agents are fully mixed with the macromolecular carriers in the matrix under proper mixing conditions with the colloidal particle matrix in proper proportion, so that the pre-dispersed powder of the rubber auxiliary agents is fully wrapped by the macromolecular carriers, and the pre-dispersion effect of the rubber auxiliary agents in the colloidal particle matrix is achieved. The predispersion effect is particularly advantageous, compared with the situation of powdery feeding or separate feeding of the rubber auxiliary agent, the predispersion master batch composition according to the invention has the advantages that the rubber base material and the high polymer uniformly wrap the rubber accelerator, so that the compatibility of the rubber accelerator and the high polymer is improved, and the time for dispersing the rubber accelerator in rubber is greatly shortened. In addition, the masterbatch particle composition only needs to be added at one time, so that the masterbatch particle composition is very convenient to use and feed, the weighing and feeding time is reduced, and the processing efficiency is greatly improved.

The predispersed masterbatch composition according to the invention is particularly advantageously applied to rubber for sealing rings. The master rubber particles can promote the stable and uniform generation of cross-linking bonds in the rubber vulcanization process, and avoid the problems of nonuniform formation, poor air tightness and the like of the vulcanization bonds caused by insufficient dispersion of a rubber accelerator, so that the prepared sealing ring can meet the requirements of high elasticity and high air tightness.

Moreover, because each rubber auxiliary agent, particularly the vulcanization accelerator, is pre-dispersed firstly, the dispersibility of the mixed accelerator is improved, and the interaction between the accelerators is obviously improved. Particularly, under the interaction of an accelerator scorch-proof group, the scorching time of rubber can be prolonged, and the production and processing safety of the sealing ring is improved; meanwhile, under the action of the promoting groups of the accelerators, the vulcanization speed is improved, and the vulcanization reaction period is shortened.

The following examples are illustrative of the compositions and methods of the present invention and are not intended to be limiting thereof. Suitable modifications and adaptations of the various conditions and parameters normally encountered in the art and which are obvious to those skilled in the art are within the scope of the invention.

Examples

The source of the raw materials used in the examples and the main properties were as follows:

ethylene propylene diene monomer: compton, usa, 75 parts of white-filled paraffin oil, ENB type, mooney viscosity ML125 ℃ ═ 48, ethylene ═ 67%.

Naphthenic oil: nytex810, a nylon naphthenic rubber oil.

EVA resin: korean LG, brand 260, index: the VA content is 28%; melting point, about 70 ℃.

Stearic acid: shanghai Yanan oil chemical plant Co., Ltd., saponification value (mgKOH/g) 205-; the acid value (mgKOH/g)203-218, and the freezing point is more than or equal to 57 ℃.

Zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, dipentamethylenethiuram tetrasulfide: self-made, the purity is more than 99.5 percent

Example 1:

1. weighing 60 parts by weight of ethylene propylene diene monomer, 25 parts by weight of naphthenic oil, 15 parts by weight of EVA resin and 15 parts by weight of stearic acid, putting into an internal mixer, heating to 95 ℃, and mixing for 20min to obtain a first premix;

2. weighing zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide in a weight ratio of 0.8:1.5:1:1.5, and mixing thoroughly to obtain a second premix;

3. weighing 25 parts by weight of the first premix and 75 parts by weight of the second premix, putting the first premix and the second premix into an internal mixer, gradually raising the temperature to 65 ℃ under the high shear force of about 0.55MPa and at the rotation speed of about 75r/min, and mixing for 5min to obtain a rubber material;

4. and putting the rubber material into an extruder to be extruded and cut into particles to obtain the final pre-dispersed masterbatch particles.

Performance testing

In addition, a mixture of a powder of a vulcanization accelerator and a single accelerator masterbatch was prepared, wherein the vulcanization accelerator components and the mass were the same as those of the vulcanization accelerator contained in the predispersed masterbatch obtained in example 1.

The pre-dispersed masterbatch particles, the powders of the mixed vulcanization accelerators and the mixture of single accelerator masterbatch particles obtained in example 1 were each subjected to a sulfur change test (15 minutes at 160 ℃) in an Ethylene Propylene Diene Monomer (EPDM) vulcanization system. The sulfur change results show an increase in TS1 for the mixed pre-dispersed masterbatch pellet according to example 1 of 5% and 2% and a decrease in TC90 of 7% and 4% respectively over the powder of the mixed vulcanization accelerator and the single accelerator masterbatch pellet.

Example 2:

1. weighing 55 parts by weight of ethylene propylene diene monomer, 28 parts by weight of naphthenic oil, 17 parts by weight of EVA resin and 14 parts by weight of stearic acid, putting into an internal mixer, heating to 87 ℃, and mixing for 22min to obtain a first premix;

3. weighing 20 parts by weight of the first premix and 80 parts by weight of the second premix, putting into an internal mixer, gradually heating to 55 ℃ under the high shear force of about 0.55MPa and 100r/min of rotation speed, and mixing for 5min to obtain a rubber material;

4. and putting the rubber material into an extruder, extruding and cutting into granules to obtain the pre-dispersed masterbatch particles.

Performance testing

In addition, a mixture of a powder of a vulcanization accelerator and a single accelerator masterbatch was prepared, wherein the vulcanization accelerator components and the mass were the same as those of the vulcanization accelerator contained in the predispersed masterbatch obtained in example 2.

The pre-dispersed masterbatch particles, the powders of the mixed vulcanization accelerators and the mixture of single accelerator masterbatch particles obtained in example 2 were each subjected to a sulfur change test (15 minutes at 160 ℃) in an Ethylene Propylene Diene Monomer (EPDM) vulcanization system. The sulfur change results show an increase in TS1 for the hybrid pre-dispersed masterbatch according to example 2 of 4% and 2.5% and a decrease in TC90 of 5.5% and 3.5% respectively over the powder of the hybrid vulcanization accelerator and the single accelerator masterbatch.

Claims

1. A pre-dispersed masterbatch composition comprising a first premix and a second premix, wherein the first premix comprises a rubber substrate, an EVA resin, a dispersant, a processing oil and optionally other processing aids, the second premix comprises two or more vulcanization accelerators, the first premix comprises 10 to 35 wt% of the composition and the second premix comprises 65 to 90 wt% of the composition, based on 100 wt% of the masterbatch composition,

wherein the second premix consists of zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide,

wherein the weight ratio of the zinc dimethyldithiocarbamate, the zinc dibutyldithiocarbamate, the zinc diethyldithiocarbamate and the dipentamethylenethiuram tetrasulfide is 0.5-1: 1-2: 1: 1.5.

2. The masterbatch composition of claim 1, in the first premix,

weight percent (%) Rubber matrix 30～70 Processing oil 15～40 Dispersing agent 7～17 EVA resin 5～20，

3. The masterbatch composition of claim 1, in the first premix,

weight percent (%) Rubber matrix 40～60 Processing oil 18-25 Dispersing agent 10～15 EVA resin 10～17，

4. The masterbatch composition of claim 1, comprising, based on 100% by weight of the composition:

a)15-35 wt% of a first pre-mix comprising, in parts by weight,

50 to 70 parts by weight of a rubber base,

20-30 parts by weight of processing oil,

10 to 20 parts by weight of a dispersant, and

10-20 parts by weight of an EVA resin;

b)65 to 85 wt% of a second premix comprising zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide in a weight ratio of 0.5 to 1:1 to 2:1: 1.5.

5. The masterbatch composition of any one of claims 1 to 4, wherein the rubber substrate is selected from the group consisting of: ethylene propylene diene monomer, nitrile rubber, styrene butadiene rubber, acrylate rubber, epichlorohydrin rubber or chloroprene rubber.

6. The masterbatch composition of claim 5, wherein the rubber substrate is ethylene propylene diene monomer.

7. The masterbatch composition of any one of claims 1 to 4, wherein the dispersant is selected from the group consisting of C12-C18 fatty acids and polyethylene glycol.

8. The masterbatch composition of claim 7, wherein the dispersant is stearic acid.

9. The masterbatch composition of any one of claims 1 to 4, wherein the processing oil is selected from an aromatic oil, a naphthenic oil, a paraffinic oil, or a fatty oil.

10. The masterbatch composition of claim 9, wherein the processing oil is a naphthenic oil.

11. The masterbatch composition of any one of claims 1 to 4, wherein the processing aid is selected from a stabilizer, a flame retardant, a lubricant, an antistatic agent, a coupling agent, a filler, a blowing agent, a colorant, a mold release agent, a brightener, or a combination thereof.

12. A vulcanization accelerator composition comprises zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dipentamethylenethiuram tetrasulfide, wherein the weight ratio of the zinc dimethyldithiocarbamate, the zinc dibutyldithiocarbamate, the zinc diethyldithiocarbamate and the dipentamethylenethiuram tetrasulfide is 0.5-1: 1-2: 1: 1.5.

13. The vulcanization accelerator composition according to claim 12, which is used for a rubber for sealing.

14. A method for preparing pre-dispersed masterbatch particles, comprising the steps of:

15. The process according to claim 14, wherein the first premix and the second premix are mixed under a pressure of 0.5-0.6Mpa, a rotation speed of 50-110 r/min and a high shear force, and the temperature is gradually increased to 60-65 ℃.