WO2009019684A2

WO2009019684A2 - The industrial method of join processing of rubber and oil waste into polymer products

Info

Publication number: WO2009019684A2
Application number: PCT/IL2008/001060
Authority: WO
Inventors: Vital Serdtse
Original assignee: Sercom Ltd
Priority date: 2007-08-08
Filing date: 2008-07-31
Publication date: 2009-02-12
Also published as: IL185122A0; WO2009019684A3

Abstract

The patent offers a way of joint processing of used mineral oils, waste of hydrolysis of vegetable oils and/or animal fats as well as scrap automobile and/or other tires and/or other rubber waste. The principle of the suggested method is based on the fact that low-molecular polymers (in this case waste of vegetative oils - either mineral, or solvents and similar waste) quickly penetrate deep into high-molecular structures (in this case vulcanized rubber of scrap tires or other sources of rubber), promoting, under certain conditions, their effective and adjustable destruction while obtaining useful products. As a result of joint processing of the mentioned materials swelling takes place, as well as plasticization of vulcanized rubbers, which is followed by devulcanization. Thus, under the influence of temperature and pressure, and of adjusting additives, polymeric plastic compound that is suitable for various applications is formed. Adjusting additives that are used as retardants of the chain radical reactions are chosen from a group of insoluble phenols in water, while bis-phenol A (tetra-bis-phenol) is preferred. It was found that without applying the mentioned means, a destruction process of high-molecular part of a composition can become uncontrollable. Therefore, products with random properties are formed. Moreover, reagents which are able to immobilize sulfur (the main vulcanizing agent) and turn it into a solid inertial water insoluble substance, are added into the reaction mixture. In this case sulfur turns into a state, which is safe for the environment. Most effective sulfur immobilization reagents are iron hydro-oxides, the best of which are hydro-oxides of iron (3). Possible applications of the obtained products are: a) Waterproof materials in the construction industry, b) Additives in asphalt for improvement of a road covering, c) A dditives in various plastics, particularly i n polyethylene compositions for improvement of elastic properties, d) Additives in rubber compositions and independent manufacturing of rubber products. e) A sorbent for liophilic liquids (water and soil treatment against pollution by mineral oil and other various liophilic liquids and bioactive agents) f) A sorbent for recultivation and rehabilitation of polluted soils and grounds.

Description

The industrial method of join processing of rubber and oil waste into polymer products

Description

FIELD OF THE INVENTION

This invention relates to various applications of scrap rubber, especially tires scrap rubber. The aim of the invention is to create an effective and universal technological process which allows producing a wide variety of materials by the means of one equipment unit only, by the means of changing the parameters (such as temperature, pressure and reagents dosing).

BACKGROUND OF THE INVENTION

Nowadays several known technologies of rubber devulcanization exist, according to which carrying out the technological process results in a break of sulfuric bonds in a polymeric grid and transformation of vulcanized rubbers in plastic compound.

All these technologies are based on the process of mixing vulcanized rubber in the form of crumb, either powder or pieces, with a chemical reagent - the agent that destroys sulfuric bonds, which is solid (powder, plastic sheets), and then exposing to hashing and frictional action at either room or raised temperature.

Under such circumstances the process does not cause migrations of molecules of a reagent inside of rubber particles which would capture all of the vulcanized rubber volume and provide delivery of reagent molecules to all of vulcanizing knops of a polymeric network.

During the process, molecules of a solid reagent are not able to be dissolved during the short time in solid vulcanized rubber, to form homogeneous reactionary system and to cause devulcanization (break of sulfuric bonds without breaking polymeric chains).

At the same time it is clear, that only in homogeneous system the agent of devulcanization can cause uniform destruction of the network up to formation of rubber plastic compound with rheological properties that are similar to rheological properties of crude rubber mixes.

In that case, when the time of compulsory mixing of vulcanized rubbers with the solid agent of sulfuric bonds destruction is long enough, or the temperature of interaction is high enough, simultaneously with the destruction of sulfuric bonds a deep destruction of polymeric chains takes place. It results in sharp decline of mechanical and operational properties of repeatedly vulcanized rubbers. Attempts to eliminate this shortcoming have not led to essential success yet. The following technologies are the most known ones:

US Patent 6 387 966, US Patent 6 541 526, European Patent EP0690091, US Patent 6 831 109, US Patent 6 313 183, US Patent 6 841 710, US Patent 5 821 395.

On the other hand, it is impossible to use liquid reagent (even theoretically) in the aforementioned patented methods because of the type of equipment used - a roll mill. A liquid reagent simply slides in the roll mill nip. For the same reason (the equipment type - a roll mill) it is also impossible to use relatively high temperatures of processing.

The purpose of the suggested invention is creation of technology in which at the first stage of the technological process a migration of molecules of the agent of sulfuric bonds specific destruction will take place during a short period of time, on the entire volume of a polymeric grid (while the size of vulcanized rubber pieces does not exceed 10-15 mm).

Due to the aforementioned considerations it must be an optimal combination of chemical reagents, mechanical equipment and temperature conditions.

SUMMARY OF THE INVENTION

The desired result is reached by preliminary dissolving the specific destruction agent of sulfuric bonds in an organic liquid. This organic liquid is characterized by capability to swell at temperatures that do not exceed 70 C in vulcanized rubber. It is necessary, that the degree and the rate of swelling would provide an increase in volume of rubber at swelling of not less than 5-10 %, within the timeframe of less than 24 hours. It is desirable, that time of swelling would be shorter and would not exceed 1-6 hours. It is also desirable that a swelling degree would not be less than 15-20%.

In case that all the requirements are fulfilled, the molecules of the specific destruction agent of sulfuric bonds will definitely reach practically all sulfuric bonds and during the processing of rubber into a regenerate at raised temperatures, deep devulcanization of vulcanized rubber will occur.

As hydrophobic org anic liquids our products of choice are products of oil refining - g asoline, kerosene, lubricating oil (including used lubricating oil), liquid products of processing of stone and brown coal, combustible slates and so forth.

The following paragraph presents an explanation of the main conceptions about such materials that guarantee their interchangeability:

1. Automotive or lubricating oils generally are saturated hydro-carbons, characterized by normal structure and common formula CnH2n+2. During its exploitation oils are exposed to thermal and oxygenation actions, mechanical friction, polluted by metal nano- and microparticles. Meanwhile oils undergo several chemical transformations. a) Thermo-destruction: Macromolecules split and form low molecular weight hydro-carbons. Double bonds appear on new molecules ends. In this manner, molecules with common formula CnH2n are formed. b) Double bonds on chain ends are characterized by high chemical activity and therefore they are rather easily oxygenated, therefore carbonic acids of common formula CnH2nCOOH are accumulated in the oils. c) Partial dehydrogenization of hydro-carbon molecules occurs under temperature action (acceleration takes place in the presence of metallic nano-particles). As a result, there is also formation of double bonds not on molecules ends, but in the middle. If a water vapor penetrates into the oil, hydrolysis of these double bonds occurs, w ith formation of alcohol groups -OH. Oxygen bridges between hydro-carbon molecules are created as well.

An accumulation of oxygenated groups in oils decreases the oil's quality as a lubricant. But at the same time these new functional groups are just those chemical agents that provide scrap rubber devulcanization under the aforementioned technological conditions.

At the same time, such waste oil is a very good plasticizer for rubber during devulcanization process. Therefore, waste machine oil can be a very valuable product for scrap rubber processing into new products.

2. During the processing of vegetable oils and animal fats waste products such as fat acids and alcohols are formed. As a rule these waste products are not being used or their use is extremely limited. However, they are very effective agents for rubber devulcanization.

As agents of sulfuric bonds specific destruction we chose to use individual and/or total water- insoluble fat and fat-aromatic saturated and non-saturated acids, in particular products of hydrolysis of vegetable oils and animal fats.

In order to achieve more flexible management of regenerate properties, speed regulators of chain radical reactions (inhibitors) are entered in reactionary system. Regulators are chosen from group of insoluble phenols in water, mainly, bis-phenol. The following technical substances - the analogues of bis-phenol which are manufactured under various commercial names, can be used also:

AgeRite Superlite - polybutylated bisphenol A,

Akrochem Antioxidant 235 - 2,2methylene-bis(4-methyl 6 tertiary butyl phenol,

Anox 29 - phenolic 2,2 ethylidene bis(4,6-dit-butylphenol),

Antioxidant 1024 - high molecular weight hindered phenol,

Antioxidant 2246 - 2,2-methylene-bis(4-methyl-6-butylphenol), and others.

For ecological safety of the process, that is, sulfur immobilization during the process, hydro-oxides of iron are added into the reaction mixture.

In order to initiate the interaction of the agent of sulfuric bonds specific destruction with C-S and S- S bonds in vulcanization network knobs, the temperature of a reactionary mix must be raised up to 150-300 C. The reason of such wide interval of offered temperatures is varying temperatures and time of temperature influence, results in obtaining products that can be used for various purposes. Such products can be:

- Secondary rubber, suitable for secondary (repeating) vulcanization and manufacturing of rubber- technical articles,

- Fireproof and soundproof materials,

- Additives to asphalt,

- Additives to secondary polymers (polyolephines, polystyrene, shock-resistant polystyrene, polyvinylchlorid, polycarbonates and so on),

- Sorbents for hydrophobic liquids and gases.

DETAILED DESCRIPTION OF THE INVENTION

Organic acids, hydrophobic solvent and a retardant of chain radical reactions, which is chosen from group of water-insoluble phenols (preferably bis-phenol) are mixed in a mixer at temperature of 20-70 C until obtaining a liquid homogeneous mix.

Then tetra-bis-phenol (bis-phenol A) and hydro-oxide of iron (3) are added into this mixture. Rubber pieces, or crumb, or scorch, or fine rubber products are carefully mixed in knidler- or brabender-type mixer with the aforementioned separately prepared liquid homogeneous mix.

The temperature of the mix in knidler- or brabender-type mixer is raised up to 30-70 C and at periodic (once in 20-40 minutes) hashing the mix is maintained there during 1 to 23 hours. Afterwards, a chain radical reactions retardant (preferably bis-phenol) is entered and the hashing is continued during another 30-60 minutes.

The mixture is entered i nto a high pressure device (100-500 at), for example, in press or in extruder, equipped with a die with round or crack apertures, and is pressed through these apertures. The temperature in the high pressure device must be in an interval from 150 up to 300 C according to the temperature regime shown in the figure, depending on the material type which is to be produced.

The material leaves the device for cooling to a room temperature by air, or water and /or by water solution containing substances that neutralize harmful emissions from the reactionary mix. In the case of using water or water solution a drying process is necessary.

Further, the obtained product is exposed to further processing (for example, granulating) and packing depending on its consistence, which, in turn, is defined by the purpose of the commodity product. Every application of obtained material needs its special processing parameters depending, first of all, on material consistence.

Examples are presented in table 1, the examples illustrate the most typical applications and the conditions for their obtaining.

H EXAMPLE 1

The aim of this example was to produce an addition to asphalt. Waste machine oil was used as swelling agent - 10 weight parts. As a destruction agent stearin was used - 5 weight parts. Bis- phenol A was used as a radical inhibitor - 0.5 weight parts. All these materials were mixed together with 100 weight parts of rubber crumb in stirrer type mixer during 1 hour under the temperature of 40 degrees Celsius.

Then the mixture was entered into an extruder, in which 3 heating zones existed as well as a heated die on outlet. The temperatures were as following: 1^st zone - 100 C degrees, 2^nd zone - 130

C degrees, 3^rd zone and die - 150 C degrees. The processing time in the extruder, which was controlled by rotation per minute, was 30 sec.

The obtained material was tested in an asphalt laboratory and was found satisfactory for its purpose.

Other examples described in table 1 were carried out in the same manner (see table 1).

S Table 1 : EXAMPLES. Below examples of the offered method execution are presented. The criteria of experiences results estimation was conformity to technical requirements to the given kind of materials.

V

V

References Cited (Referenced By)

6,831,109 Dec.2004 Beirakh 521/41

6,387,966 May 2002 Goldshtein 521/41

EP0690091 Mar.1996 Sekhar C08J 11/10

6,335,377 Jan.2002 Izumoto C08J11/04

6,310,122 Oct.2001 Butler 524/60

5.683.498 Nov.1997 HesD 106/273.1

2

Claims

1. Technology of joint processing of: a. used mineral oils, b. waste of processing of vegetable oils and animal fats, c. vulcanized rubber from scrap automobile, airplane, tractor and other tires, and also from conveyor belts and other rubber-technical articles, as well as from sub-standard, partially vulcanized rubber mixes by consecutive operations of mixing, holding and heating of components in a mixer, which is followed by processing of a reactionary mix by the means of extrusion.

2. Technology described in claim 1, wherein the content for joint processing has the following ratios of components (weight parts):

• vulcanized rubber (pieces, a crumb, scorch, little articles): 100,

• hydrophobic liquid, for example used lubricating oil: 5-20,

• individual and/or total fat and/or fat-aromatic acids, for example, waste of vegetable oil hydrolysis: 2-10,

• retardants of chain radical reactions, chosen from group of insoluble phenols in water, preferably, bis-phenol A: 0.3-1

• reagents, which are used for sulfur immobilization, selected from iron hydro-oxides group, hydro-oxide of iron (3) is preferred: 0.5-1.5

3. Technology described in claims 1 and 2, wherein individual and/or total fat and/or fat- aromatic acids, for example, sour waste of hydrolysis of vegetable oils and/or animal fats are mixed with hydrophobic I iquid, for example, used lubricating oil, until obtaining a homogeneous mix and inhibitors of chain radical reactions, preferably tetra-bis-phenol and reagents which are used for sulfur immobilization, preferably hydro-oxide of iron (3) are added to the aforementioned mix.

4. Technology described in claims 1 and 2, wherein individual and/or total fat and/or fat- aromatic acids, for example, sour waste of hydrolysis of vegetable oils and/or animal fats are mixed with hydrophobic I iquid, for example, used lubricating oil, until obtaining a homogeneous mix and inhibitors of chain radical reactions, preferably tetra-bis-phenol and reagents used for sulfur immobilization, preferably hydro-oxide of iron (3) are added into the aforementioned mix, after that the mixture is exposed to temperatures between 20-70 C.

5. Technology described in claims 1 and 2, wherein vulcanized rubber (pieces, crumb, scorch, and little articles) is mixed with a mix obtained according to claims 3 and 4.

6. Technology described in claims 1 -5, wherein the described mixture is prepared at temperatures between 20-70 C.

7. Technology described in claims 1 and 6, wherein the described m ixer for mixture and heating of components of a mix should provide intensive grinding of firm components of a mix and compulsory diffusion of liquid components in firm particles of the mix.

8. Technology described in claims 1 and 6, wherein the aforementioned mixer is a ball mill.

9. Technology described in claims 1 and 6, wherein the mixer is a mixer with Z-shaped blades.

10. Technology described in claims 1, 8 and 9, wherein the temperature in the mixer is between 30 and 100 C.

11. Technology described in claim 1, wherein the time of stay of the components mix in a mixer is between 1 and 24 hours.

12. Technology described in claim 1, wherein the extrusion of a reactionary mix is executed by an extruder or a thermo-plastic machine or other analogous machine, through round apertures, which diameter is less than 1 mm.

13. Technology described in claim 1, wherein the extrusion of a reactionary mix is executed through crack apertures that have a cross-section section of less than 1 mm.

14. Technology described in claim 1, wherein the temperature of a reactionary mix during extrusion through apertures is maintained in an interval of 150 and 300 C.

15. Technology described in claim 1, wherein partially devulcanized fine crumb is obtained by holding the temperature regime according to curve 1 described in figure 1.

16. Technology described in claim 1, wherein devulcanizate (secondary rubber for repeating vulcanization) is obtained by holding the temperature regime according to curve 2 described in figure 1.

17. Technology described in 1, wherein a sorbent (granulated material for hydro-carbon absorption) is obtained by holding the temperature regime according to curve 3 described in the figure 1.

18. Technology described in 1, wherein the partially destructurized devulcanizate (a component of bitumen compositions) is obtained by holding the temperature regime according to curve 3 described in figure 1.

19. Technology described in claim 1, wherein a material that is formed at extrusion through apertures is cooled up to room temperature by air.

io

20. Technology described in claim I₇ wherein a material that is formed at extrusion through apertures is cooled up to room temperature by water.

21. Technology described in claims 1-14 and 16, wherein a material that is formed at extrusion through apertures is cooled up to room temperature by water solution containing substances, neutralizing harmful emissions from a reactionary mix.

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