KR101491969B1 - Process for production of high quality insoluble sulfur - Google Patents

Abstract

The present invention relates to a method for manufacturing high quality insoluble sulfur by removing liquid sulfur by being passed through a vapor-liquid separator before supplying sulfur vapor to a cooler. The method for manufacturing high quality insoluble sulfur according to the present invention enables high quality insoluble sulfur in which a residue amount is low (100 Mesh 1.5% or less) without problems in a manufacture process such as pipe blockage and the like. The insoluble sulfur manufactured by the manufacturing method of the present invention is able to be used as a vulcanizing and curing agent in rubber industries and, especially, tire manufacture by comprising 90% or more of insoluble sulfur on total sulfur (IS), 1.5% or less of residues, 71 % or more of HTS, wherein a particle size is 5-30 μm.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a process for producing high-quality insoluble sulfur,

The present invention relates to a process for producing high quality insoluble sulfur. More particularly, the present invention relates to a method for producing high quality insoluble sulfur by passing liquid sulfur through a gas-liquid separator before supplying sulfur vapor to the cooler.

Insoluble sulfur refers to sulfur which is insoluble in carbon disulfide (CS ₂ ) and is also referred to as polymeric sulfur. Generally, this type of sulfur is known as a polymer having a molecular weight of thousands of sulfur atoms of 100,000 or more and a particle size of 5 to 30 μm. Insoluble sulfur is an amorphous substance and is distinguished from soluble sulfur whose form is a crystal.

A commonly known method for producing insoluble sulfur consists of heating liquid sulfur (S ₈ ) into sulfur vapor and then rapidly cooling the sulfur vapor using carbon disulfide to form a polymer (- [S] n-) sulfur.

Insoluble sulfur is mainly used as a crosslinking (vulcanizing) agent in rubber compositions.

Although soluble sulfur can perform the basic cross-linking (crosslinking) for rubber compositions, the inclusion of soluble sulfur in the rubber composition causes defects in the rubber products made by making processing difficult. The two most common problems caused by the use of soluble sulfur are 'bloom' and 'bin scorch'. Sulfur blue is the crystallizing action of sulfur on the surface of rubber products. It is caused by the movement of sulfur from the inside to the surface of the rubber product. This phenomenon occurs because the sulfur is soluble in the rubber at the masticating temperature. When the mixture is cooled after mixing, the solubility is reduced and a supersaturated solid solution is formed. When the mixture is cooled and the solubility is reduced, the sulfur begins to emerge from the solid solution and travels to the surface of the rubber article to form crystals. This surface bloom is a serious problem. Because it destroys the natural viscosity of the rubber within the area affected. When several layers of rubber are assembled to fabricate tires, belts, hoses, etc., defects such as bubbles are created due to interference of natural bonds between adjacent layers due to sulfur blue.

On the other hand, when insoluble sulfur is used as a cross-linking agent, surface bloom does not occur. The insoluble sulfur is uniformly distributed throughout the rubber composition during the mixing step and does not enter the solution in the rubber composition. The distribution of insoluble sulfur remains in a dispersed state, no change in concentration occurs, and no migration of sulfur occurs. Insoluble sulfur is reduced to soluble form and enters the solution only when the final article is vulcanized. The vulcanization reaction takes place simultaneously, and the sulfur is part of the rubber polymer product. Thus, the sulfur is chemically bonded, and no bluing appears at the same time as the cooling of the rubber polymer.

Another significant problem caused by the use of soluble sulfur in rubber compositions is the phenomenon of Vince Kochi. The phenomenon of Vince Coochi occurs when the uncured rubber composition is stored after being sufficiently mixed (i.e., mixed, pulverized, etc.). The non-curing composition is temperature sensitive, and curing (i.e., crosslinking) begins too hastily if the storage temperature is not properly controlled. This phenomenon is known as 'Vince Kochi'.

When insoluble sulfur is used, Vince cocci is inhibited. Since insoluble sulfur is used for the reaction only when it reaches the curing (vulcanization) temperature, no reaction takes place at low temperatures. Under low temperatures, the insoluble sulfur only remains as a dispersed solid surrounded by the rubber until vulcanization occurs.

As described above, a method for producing insoluble sulfur has been developed much because of technical advantages provided by insoluble sulfur compared to soluble sulfur. The content of insoluble sulfur (IS) in the final product produced by the conventional method is less than 90%, and the high heat stability (HTS: content not dissolvable and decomposed after heating for 15 minutes or more at 105 캜) among insoluble sulfur is 70 (100% by weight or more) and 1.5% by weight of the sieve residue (100 mesh), so that a high quality (IS content 90% or more, HTS 71% or more and soul residue 1.5% or less) insoluble sulfur which can be used as vulcanizing agent in the tire industry is required Has come.

U.S. Patent No. 2,419,309 discloses a method for producing insoluble sulfur by a cooling method using carbon disulfide. Discloses a method for producing an insoluble sulfur in which sulfur is heated to vaporize and quenched to carbon disulfide at a temperature of 60 占 폚 or lower. According to this method, most of the soluble sulfur is dissolved in the carbon disulfide solution, and the insoluble sulfur is solidified (pulverized) and remains dispersed in the carbon disulfide. The resulting insoluble particles of sulfur are then separated from the carbon disulfide by filtration, centrifugation and similar techniques and finally dried.

EP 0 053 832 discloses a process for the production of insoluble sulfur comprising the steps of vaporizing sulfur, then mixing the hydrogen sulfide with sulfur vapor, quenching and separating the insoluble sulfur in the quench medium. According to this method, the addition of hydrogen sulfide to the sulfur vapor to be treated improves the flowability of the material being treated and improves the stability of the final insoluble sulfur product and virtually inhibits the simultaneous production of tails which contaminate the final product with black spots Lt; / RTI >

On the other hand, when the sulfur vapor is transferred to the cooler, the sulfur vapor is generated by the pressure and the speed of the sulfur vapor flow and the sulfur vapor is generated due to the condensation phenomenon of the gas. Thus, a large amount (20 to 30% If this liquid sulfur is quenched, it becomes a granule instead of a powder form, causing clogging of the pipe or increasing the sludge content in the resulting insoluble sulfur (final product), making it difficult to produce high quality insoluble sulfur. However, in the conventional manufacturing methods, such problems are not recognized or solved, and problems such as clogging of pipes are caused, and it is difficult to produce high quality insoluble sulfur.

Accordingly, it has been urgently required to develop a method for producing high-quality insoluble sulfur having a low sludge content (100 mesh less than 1.5%) without causing manufacturing problems such as clogging of piping.

U.S. Patent 2,419,309 European Patent 0 053 832

As a result of continuing the study, the inventors of the present invention have found that by removing liquid sulfur by passing through a gas-liquid separator before supplying sulfur vapor to a cooler, the body residual amount is low (100 mesh less than 1.5%) and high-quality insoluble sulfur And the present invention has been completed.

Accordingly, an object of the present invention is to provide a method for producing a high-quality insoluble sulfur having a low sieve residue (100 Mesh 1.5% or less).

In order to accomplish the object of the present invention, the present invention provides a process for producing high quality insoluble sulfur comprising the steps of:

I) heating the sulfur to vaporize;

Ii) passing the sulfur vapor through a gas-liquid separator to remove liquid sulfur;

Iii) rapidly cooling the sulfur vapor from which the liquid sulfur has been removed with carbon disulfide at 30 to 60 ° C to form insoluble sulfur;

Iv) aging the insoluble sulfur in the carbon disulfide suspension; And

v) centrifuging the aged insoluble sulfur and drying.

If necessary, the production method of the present invention may further comprise the step of oil coating vi) insoluble sulfur obtained in step v).

Step i) Vaporization

The sulfur is heated to vaporize.

It is preferable to use liquid sulfur of 130 to 145 占 폚, but not limited thereto.

The vaporization can be effected by heating the sulfur to 500 to 650 ° C, preferably 580 to 635 ° C, using a vaporization vessel equipped with a conventional boiler.

The pressure of the vaporizing vessel rises in proportion to the temperature of the sulfur vapor as shown in Table 1 below, and can be appropriately adjusted by those skilled in the art.

TEMP '(占 폚) PRESS '(kg / cm2G) 500 1.0 550 2.5 570 3.5 580 4.0 600 5.0 610 5.8 620 6.5 630 7.5 635 9.0 640 10.0 650 11.0

Step ii) Gas-liquid separation

The sulfur vapor from step i) is passed through a gas-liquid separator to remove liquid sulfur.

The liquid sulfur (sulfur drop) generated by the condensation phenomenon of the gas or the gas is caused by the movement of the sulfur vapor stream. Before the sulfur vapor is supplied to the cooler, it is passed through the gas-liquid separator to remove the liquid sulfur .

The gas-liquid separator is preferably provided with at least one baffle near the inlet where the sulfur vapor is introduced and the outlet where the sulfur vapor is introduced, and the liquid sulfur (sulfur drop) And the piping connected to the lower part of the gas-liquid separator is recirculated to the sulfur vaporization step. The liquid collected at the bottom of the gas-liquid separator by the naked eye through the vent is recycled to the sulfur vaporization tank if it has a foreign-free wine color. The gas-liquid separator is also preferably equipped with a valve at the outlet to control the flow rate of sulfur vapor to the cooler. Sulfur vapor outflow (supply) point to the cooler is also when the sulfur vapor becomes visibly yellow through the vent.

 The pressure of the gas-liquid separator can be appropriately adjusted by a person skilled in the art in proportion to the temperature of the incoming sulfur vapor, and is preferably 4.5 to 9 kg / cm 2.

The sulfur vapor introduced into the gas-liquid separator normally contains 20 to 30% (v / v) of liquid sulfur but the sulfur vapor flowing out after the gas-liquid separation contains liquid sulfur of less than 5% (v / v) .

The supply of sulfur vapor from the gas-liquid separator to the cooler is preferably carried out at a flow rate of 400 to 600 kg / hr.

In the case of using sulfur vapor passing through the gas-liquid separator, the insoluble sulfur produced has a body sludge content of 1.5% or less at 100 mesh.

Step iii) Cooling (forming insoluble sulfur)

The sulfur vapor from which the liquid sulfur is removed is supplied to a cooler filled with carbon disulfide at 30 to 60 ° C at a flow rate of preferably 400 to 600 kg / hr, and quenched to form insoluble sulfur.

The formed polymer sulphate deforms its plastic nature until it reaches the same aspect as the powder.

The carbon disulfide is charged to account for 30 to 50% of the cooler, and the temperature of the carbon disulfide is maintained at 30 to 60 ° C through a heat exchanger installed in the cooler recirculation pipe.

The carbon disulfide in the lower portion of the cooler is continuously recycled to the upper portion of the cooler in accordance with the supply of sulfur vapor. The recycle rate is preferably 100 to 150 ton / hr

The lower part of the cooler is preferably equipped with a stirrer and agitated appropriately so that the insoluble sulfur formed is well suspended in the carbon disulfide. Soluble sulfur other than insoluble sulfur is dissolved in the carbon dioxide disulfide medium and is present. The sulfur vapor released is recirculated and the suspension is allowed to proceed to the aging stage.

The solids concentration in the resulting suspension is about 7-12%, preferably 10% or less.

Step iv): Aging

The insoluble sulfur in the suspension in step iii) is aged.

The purpose of this step is to increase the thermal stability of the resulting insoluble sulfur. The thermal stability of the resulting polymer sulphate is increased to between 15 and 25% compared with the thermal stability of the polymer sulphide not undergoing aging.

The suspension is fed to an aging unit maintained at 50 캜 or less so as to be filled up to 50% (v / v) or less and agitated for 30 to 60 minutes so that the insoluble sulfur is aged.

Step v) Centrifugation and drying

The insoluble sulfur, soluble sulfur and carbon disulfide mixed in the suspension obtained in step iv) are separated by techniques known in the art.

In general, physical separation of insoluble sulfur is carried out by centrifugation, which is a known technique for the treatment of temperature sensitive solids, and drying is carried out by conventional methods to avoid thermal decomposition.

The insoluble sulfur produced according to the process of the present invention is a high quality insoluble sulfur with the following characteristics:

Test Items Test Methods standard color Visually Yellow powder IS (insoluble sulfur in the total product sulfur) content ASTM D4578-89 At least 90% Particle size of insoluble sulfur Electron microscope 5 to 30 μm FINENESS RETENTION WET SCREEN 100 ¹ ASTM D4572-89 Up to 1.5% RKDUFRKAFID (60 DEG C, 2HR) ASTM D4571-94 Up to 0.3% Acid component (AS H2SO4) ASTM D4569-89 Up to 0.5% HTS (thermal stability; heating in paraffin oil at 105 ° C for 15 minutes) ² At least 71% MELTING POINT At least 118 ° C ASH CONTENT ³ Up to 0.1% SPECIFIC GRAVITY AT 25 ℃ ASTM 2598 At least 1.6 ± 0.03

¹ body residue: The final product in powder form is passed through a standard mesh (100 mesh) sieve while washing with running water to obtain a percentage of the content of the substance remaining on the standard

= (Residual amount on the standard g / weight of the sample (initial product) g) X 100

² HTS: Percentage of the content (amount of IS remaining after heating) that is dissolved in the carbon disulfide and decomposed after heating the powdery final product at 105 占 폚 for 15 minutes or more

= [Insoluble content (IS) g / (weight of sample g X IS% in sample)] X 100

³ times: Percentage of residue content after heat treatment of final product (sample)

= (Final residual minutes g / weight of sample g) X 100

Unless indicated otherwise in the present invention,% means% by weight.

Step vi) Oil coating

If desired, the insoluble sulfur prepared in step v) may be coated with oil for storage stability.

The oil coating can be carried out by mixing the insoluble sulfur with the mineral oil known in the art in a ratio of 6.5: 3.5 to 9: 1 and mixing at a high speed using a mixer to prevent temperature rise.

The method for producing insoluble sulfur according to the present invention is a method for producing insoluble sulfur, which eliminates liquid sulfur through a gas-liquid separator and does not cause manufacturing problems such as clogging of piping, And the sulfur vapor can be stabilized through the gas-liquid separator to be uniformly supplied to the cooler and the flow rate of the supplied sulfur vapor can be easily controlled.

Since the insoluble sulfur produced by the production method of the present invention has a high quality of not less than 90% of IS (INSOLUBLE SULFURE ON TOTAL SULFUR), not more than 1.5% of body sludge, not less than 71% of HTS and a particle size of 5 to 30 μm, Can be used as a vulcanizing agent in the industry, especially in the manufacture of tires.

1 is an example of a flow chart of the entire process of the method for producing insoluble sulfur according to the present invention.
2 is a view showing an example of a gas-liquid separator used in the present invention.
FIGS. 3A and 3B are electron micrographs of insoluble sulfur particles prepared in Examples 1 and 2. FIG.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example

Example  One

Sulfur vapor at about 130 ° C is vaporized at about 635 ° C to produce sulfur vapor, which is fed to a gas-liquid separator. Under 9 kg / cm 2, the sulfur vapor becomes bright yellow (confirmed by venting) (Liquid sulfur) was removed from the sulfur vapor and sulfur vapor was supplied to a cooler having about 40% of carbon disulfide charged at 30 to 60 ° C at a flow rate of 500 kg / hr. Lt; / RTI > At this time, the solution was continuously recycled from the bottom of the cooler to the top at 120 tons / hr. The internal temperature of the cooler was maintained at 30 to 60 ° C through a heat exchanger installed in the recirculation pipe of the cooler, the pressure was maintained at 1.0 to 1.2 kg / cm 2, and a carbon disulfide suspension containing insoluble sulfur formed by a stirrer installed at the bottom of the cooler was stirred Respectively.

At the bottom of the cooler, 12,000 kg / hr of suspension was pumped and fed to an aging machine maintained at 50 ° C or less to be filled with 40% (v / v) and aged for 45 minutes to agitate the insoluble sulfur in the suspension.

After aging, the suspension was centrifuged to remove the carbon disulfide solution in which the soluble sulfur was dissolved, and then vacuum-dried to obtain an insoluble sulfur having the following characteristics of yellow powder. The particle size was photographed with an electron microscope 3a: < RTI ID =

IS content: 92%

HTS (105 [deg.] C / 15 min): 71%

Sieve residue (100 MESH): 1.3%

Heat loss (60 ℃ / 2 hours): 0.3% or less

Specific Gravity: 1.6 ± 0.03

Melting point: 118 ℃ or higher

Ash: Not more than 0.1%

Acid content: Not more than 0.5%

Example 2

Sulfur vapor at about 130 ° C is vaporized at about 635 ° C to produce sulfur vapor, which is fed to a gas-liquid separator. Under 9 kg / cm 2, the sulfur vapor becomes bright yellow (confirmed by venting) (Liquid sulfur) was removed from the sulfur vapor and the sulfur vapor was supplied to a cooler charged with about 30% of carbon disulfide at 30 to 60 ° C at a flow rate of 600 kg / hr. Lt; / RTI > At this time, the solution was continuously recycled from the bottom of the cooler to the top at 120 tons / hr. The internal temperature of the cooler was maintained at 30 to 50 ° C through a heat exchanger installed in the recirculation pipe of the cooler, the pressure was maintained at 1.0 to 1.2 kg / cm 2, and a carbon disulfide suspension containing insoluble sulfur formed by a stirrer installed at the bottom of the cooler was stirred .

At the bottom of the cooler, 12,000 kg / hr of suspension was pumped out and fed to an aging machine maintained at 50 ° C or less to be 30% filled, and the insoluble sulfur in the suspension was aged while stirring for 40 minutes.

After aging, the suspension was centrifuged to remove the carbon disulfide solution in which the soluble sulfur was dissolved, and then vacuum-dried to obtain an insoluble sulfur having the following characteristics of yellow powder. The particle size was photographed with an electron microscope 3b:

IS content: 92%

HTS (105 [deg.] C / 15 min): 74%

Sieve residue (100 MESH): 1.4%

Comparative Example

As soon as the sulfur vapor of about 130 ° C was vaporized at about 635 ° C and the sulfur vapor was produced, it was immediately supplied to a cooler charged with about 40% of carbon disulfide at 30 to 60 ° C and cooled. Immediately after the cooling reaction, the liquid sulfur is cooled in a granular form, leading to instability of cooler pump discharge pressure, surge of cooler level and temperature, instability of the sulfur level and temperature of the vaporized boiler, load increase of the cooler agitator, After one hour, the piping was clogged and no further manufacturing progress was possible.

Claims (8)

I) heating the sulfur to 500 to 650 ° C to vaporize;
Ii) passing the sulfur vapor through a gas-liquid separator to remove liquid sulfur;
Iii) rapidly cooling the sulfur vapor from which the liquid sulfur has been removed with carbon disulfide at 30 to 60 ° C to form insoluble sulfur;
Iv) aging the insoluble sulfur in the carbon disulfide suspension; And
V) centrifuging the aged insoluble sulfur and drying
≪ / RTI > The method of claim 1, further comprising oil coating the insoluble sulfur after step (v). The method for producing insoluble sulfur according to claim 1, wherein at least one baffle is provided in the vicinity of an inlet through which the sulfur vapor flows into the gas-liquid separator and an outlet through which the sulfur vapor flows. The method of claim 1, wherein the sulfur vapors discharged after the gas-liquid separation in step ii) contain less than 5 vol% of liquid sulfur. The method of claim 1, wherein the pressure of the gas-liquid separator is maintained at 4.5 to 9 kg / cm < 2 >. The method of claim 1, wherein the gas-liquid separator outlet is equipped with a valve capable of regulating the flow rate of sulfur vapor to the cooler. 7. The method of claim 6, wherein the sulfur vapor flow rate from the gas-liquid separator to the cooler is from 400 to 600 kg / hr. 8. A process for the preparation of a composition according to any one of claims 1 to 7, wherein the IS (insoluble sulfur in produced sulfur) content is at least 90 wt%, the sieve residue is at most 1.5 wt%, the HTS (heat stable insoluble sulfur content) Of at least 71% by weight, and a particle size of from 5 to 30 [mu] m.

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