KR101240692B1 - Method for reclaiming used-up rubber of latex - Google Patents

Abstract

The present invention relates to a waste rubber regeneration method comprising grinding waste rubber of latex material and mixing it with a Soviet accelerator to desulfurize with a twin screw extruder.
According to the present invention, since the use of 0.06 to 0.1% of the Soviet accelerator, which is almost negligible relative to the weight of the rubber, does not use the regenerated oil, it is possible to omit the maturing time required by using the regenerated oil in the conventional rubber regeneration method. Not only can it be recycled in a short time, it can reduce the manufacturing cost, and environmental problems due to odors can also be drastically improved.
In addition, the recycled rubber of the latex material can be recycled to produce a high quality recycled rubber products.

Description

Method for reclaiming waste rubber from latex material {Method for reclaiming used-up rubber of latex}

The present invention relates to a waste rubber recycling method of the latex material, and more particularly, to a waste rubber recycling method characterized in that the waste rubber of the latex material is pulverized, mixed with the Soviet accelerator and desulfurized by a twin screw extruder.

Since rubber is an essential material for modern people's life, rubber products have been developed and commercialized in various fields. These rubber products are characterized by the unique elasticity, elasticity, insulation, and the ability of liquid or gas to pass through. Therefore, it is used quite usefully.

However, due to the environmental problems in the post-use treatment and the situation in which the raw material of the rubber product depends entirely on imports, efforts to recycle the rubber products that are discarded after use are necessary.

The treatment methods of rubber waste mainly used up to now include incineration to recover thermal energy, extraction and utilization of fuel oil, chemical decomposition and utilization of monomer units, and recycling of rubber raw materials.

Among them, the recycling of rubber materials is the most effective method in terms of environmental problems and economics.

Recycling of rubber raw materials is based on the desulfurization method, which is mainly carried out chemically.

Conventional desulfurization treatment involves grinding the regenerated rubber, adding regenerated oil, and desulfurization using steam at high temperature and high pressure.The mixed oil is mixed with a large amount of regenerated oil (about 5 to 15%) and the regenerated oil is Since it needs to be aged for at least 24 hours until it penetrates, not only a lot of time is required, but also a bad odor due to the gas generated by heating the regeneration oil during desulfurization has a fatal effect on the working environment.

As an alternative to solve this problem, the waste rubber was prepared by pulverizing the waste rubber in Korean Patent No. 10-0901561 to prepare fine powdered waste rubber, and desulfurization treatment using only heat and shear force by a twin screw extruder. The desulfurization treatment method of rubber is disclosed. According to this, although the waste rubber can be desulfurized in a short time without using regenerated oil, it is not satisfactory to use the rubber regenerated by desulfurization and satisfies physical properties. To this end, there is still a problem of using a regeneration oil or using a new rubber material. In addition, since the object is a rubber product mainly composed of waste tires for automobiles such as EPDM and SBR, many parts need to be improved to recycle rubber products made of natural rubber latex materials having completely different physical properties.

Therefore, the inventors of the present invention, in order to develop a method for more efficiently recycling the waste rubber of the latex material, as a result of intensive research, finely crushed waste rubber, and then added by adding a small amount of the Soviet accelerator, biaxially according to a specific temperature gradient When the desulfurization using an extruder, it was confirmed that it is possible to efficiently produce a high-quality recycled rubber product that can maintain most of the properties of the original natural rubber latex without using regenerated oil, and completed the present invention.

Therefore, the main object of the present invention is to provide a method of reclaiming waste rubber of natural rubber latex material with high quality recycled rubber with high efficiency in a short time without using regeneration oil.

According to an aspect of the present invention, the present invention comprises the steps of: a) preparing a rubber pulverized product by grinding 50 to 2 mesh (waste) waste rubber products containing 50 to 75% or more of natural rubber latex; b) zinc pentachloro thiophenolate, bis (2-benzamidophenyl) disulfide, zinc-2-benzamido thiophenolic acid preparing a mixture by mixing one or more Soviet accelerators selected from the group consisting of (zinc-2-benzamidothiophenolate) and pentachlorothiophenol; c) the first section of 150 to 200 ° C, the second section of 180 to 250 ° C, the third section of 150 to 200 ° C and the two to four stress shear sections and the ratio of length and diameter (L / D The mixture was introduced into a twin screw extruder having 22 to 46, and desulfurized sequentially for 1 minute to 1 minute 30 seconds in the first section, 2 to 3 minutes in the second section, and 1 minute to 1 minute 30 seconds in the third section. Allowing the reaction to be carried out; And d) provides a waste rubber recycling method by a continuous extrusion method comprising the step of cooling the desulfurized rubber produced in step c).

According to another aspect of the present invention, the present invention provides a recycled rubber produced by the waste rubber recycling method, the natural rubber content of 75 to 97% by weight, the content of oil and organic matter of 3 to 25% by weight. do.

The present invention is biaxially extruded desulfurized waste rubber of the latex material, zinc pentachloro thiophenolate (zinc pentachloro thiophenolate), bis (2-benzamidophenyl) disulfide (bis (2-benzamidophenyl) disulfide), zinc Using a small amount of the Soviet accelerator selected from 2-benzamido thiophenolic acid (zinc-2-benzamidothiophenolate) and pentachlorothiophenol (pentachlorothiophenol), divided into the largest stage 150 to 200 ℃, 180 to 250 ℃ and It uses a temperature gradient of 150 to 200 ℃, characterized in that the desulfurization using a twin-screw extruder to achieve two to four times the stress shear.

Since the present invention is a method suitable for recycling latex waste rubber products, it is preferable to use waste rubber products containing more than 50% of natural rubber latex, household rubber gloves, balloons, condoms, medical rubber gloves, industrial rubber gloves This includes rain boots, medical hoses and rubber bands.

In order to facilitate heat transfer and flow inside the twin screw extruder, it is preferable to grind the waste rubber product into a twin screw extruder by using a mill or the like to inject it into the twin screw extruder. Since it is pulverized once again by the screw of the twin screw extruder after the addition, it is not necessary to pulverize finely less than 50 mesh, and when the particle diameter of the pulverized product exceeds 2 mesh, heat transfer and flow are difficult to be made smoothly even if crushed by the screw.

The grinding method is not particularly limited, but a high temperature shear grinder, a pin mill grinder, a frozen grinder or the like can be used.

In the present invention, the Soviet accelerator to be mixed with the rubber grinding material serves to shorten the desulfurization process by smoothing heat transfer and fluidity in desulfurizing the rubber grinding material, zinc pentachloro thiophenolate, bis ( One or two or more of 2-benzamidophenyl disulfide, zinc-2-benzamidothiophenolate and pentachlorothiophenol You can choose to use it. Such a Soviet accelerator may be applied by mixing the rubber powder with the rubber powder before input to the twin screw extruder, it is preferable to mix the rubber powder to be 0.06 to 0.1% when the rubber powder is 100% by weight. This is because, when the Soviet accelerator is less than 0.06%, the desulfurization process, that is, the shortening effect of the extrusion time is insignificant.

The rubber powder and the Soviet accelerator may be mixed using an agitator, and may be separately mixed and introduced into a twin screw extruder or may be placed at the inlet of the twin screw extruder to be simultaneously added with stirring.

The twin screw extruder is a two screw extruder, which is a machine that continuously extrudes by heating and flowing a raw material. Generally, it consists of a raw material feeder, a screw for transporting raw materials, a barrel in the form of a cylinder surrounding the screw, and an exit die. The barrel is divided into several parts so as to control temperature in each section.

In using the twin-screw extruder, various variables such as feed rate of raw materials, screw type and rotation speed, and temperature conditions of each barrel are applied. Therefore, in order to extrude a specific raw material into a material having desired properties, various variables are adjusted. It is important to do.

According to the present invention, it is preferable to use a twin screw extruder having a ratio of length and diameter (L / D) of 26 to 46, and a rubber pulverized product in the twin screw extruder is 150 to 200 ° C in combination of the temperature and the screw of each barrel. 1 minute to 1 minute 30 seconds (first section), 2 to 3 minutes (second section) at 180 to 250 ° C and 1 minute to 1 minute 30 seconds (third section) at 150 to 200 ℃ In this process, it is desirable to form two to four stress shear sections so that desulfurization and crystallization are possible.

More preferably, it is preferable to use a coaxial twin screw extruder having a ratio of length and diameter (L / D) of 30 to 44, and the rubber powder is 30 to 45 seconds at 160 to 180 ° C (Section 1-1 section). , 30 seconds to 45 seconds (1-2 sections) at 170 to 190 ° C., 2 to 3 minutes (second section) at 200 to 220 ° C., and 1 minute to 1 minute 30 seconds at 150 to 200 ° C. (third section ) It is good to be able to maintain, and the stress shear section is placed in two places between the 1-2 section and the second section and between the second section and the third section, respectively, so that desulfurization occurs in the first stress section and the second stress It is good to allow the chain to be formed in the shear section.

Figure 3 shows an example of the screw configuration of the twin screw extruder and the temperature configuration of each barrel that can satisfy the above conditions, the mixture of rubber crushed powder and the Soviet accelerator through the inlet of the twin screw extruder, but naturally by gravity When the input, and the rotational speed of the screw is applied to 45 to 50rpm, it can satisfy the above desulfurization conditions.

Since the present invention is for the regeneration of rubber, it is preferable to use the screw of the twin screw extruder with a sinusoidal screw focusing on the kneading function rather than the trapezoid focusing on the extrusion function.

The L / D ratio of the twin screw extruder and the arrangement of the screws determine the length of time to stay in the twin screw extruder. If the L / D ratio is high, a wide pitch screw is used. If the L / D ratio is low, a narrow pitch screw is used. According to the situation, an appropriate screw may be configured to satisfy the above conditions.

Extrusion conditions such as the ratio of the length and diameter of the twin-screw extruder, the temperature section and the holding time should be made in harmony with each other, and when all these conditions are satisfied, the high quality rubber can be regenerated.

When the rubber pulverized product is subjected to the desulfurization process as described above, it becomes a semi-solid state that is easily deformed. Therefore, by placing a specific type of adapter at the outlet of the twin-screw extruder can obtain a rubber of the desired shape.

Since the rubber after the extrusion process has a relatively high temperature due to the temperature at the time of extrusion and the shape can be easily deformed by the external pressure, it is preferable to cool the rubber immediately after the extrusion in consideration of operational safety and maintenance of the shape.

Air cooling and water cooling may be used as the cooling method, and it is more preferable to rapidly cool using the water cooling method in view of maintaining the shape of the extruded rubber.

Recycling household rubber gloves that are damaged due to long use or household rubber gloves that are discarded due to molding defects during the manufacturing process are recycled according to the above-mentioned waste rubber manufacturing method, the natural rubber content is 75 to 97% by weight, oil and It can be recycled with recycled rubber having an organic content of 1 to 5% by weight.

As described above, according to the present invention, since 0.06 to 0.1% of the Soviet accelerator is used, which is almost negligible relative to the weight of the rubber without using the regenerated oil, it is required to use the regenerated oil in the conventional rubber regeneration method. It can not only omit the ripening time, but also can be recycled in a short time to reduce the manufacturing cost, and can also significantly improve the environmental problems caused by odor.

In addition, the recycled rubber of the latex material can be recycled to produce a high quality recycled rubber products.

1 is a block diagram showing an embodiment of the present invention.
Figure 2 is a side view of the twin-screw extruder used in one embodiment of the present invention, the mixing device is provided on the top of the inlet (hopper) of the extruder, it is configured so that the rubber pulverized and the Soviet Union is mixed and then introduced into the extruder It is.
3 is a view showing a screw of the twin screw extruder used in one embodiment of the present invention. The part indicated by the dashed box in the arrangement of the screws is for the realization of the stress shear section.
4 is a graph showing the results of fourier transform infrared spectrometry (FT-IR) of rubber regenerated according to the present invention.
5 is a graph showing the results of PGC (process gas chromatography) analysis of rubber regenerated according to the present invention.
6 is a graph showing the results of thermogravimetric analysis (TGA) of rubber regenerated according to the present invention.
Figure 7 is a graph showing the measurement of the content of the inorganic additive of the reclaimed rubber according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, and the scope of the present invention is not to be construed as being limited by these examples.

Example  One.

In the present embodiment, the waste rubber for regeneration was used as a defective product generated during the manufacture of household rubber gloves, and zinc pentachloro thiophenolic acid (Bayer, Germany, trade name: Renacit 4) was used as a Soviet accelerator.

As a twin screw extruder, Ø 83 extruder M / C coaxial twin screw extruder (30L / D, number of barrels: 7) of Jinwooki (see Fig. 2) was used. Screw configuration of the twin-screw extruder was as shown in Figure 3, the barrel temperature of the first barrel 170 ℃, second barrel 180 ℃, third barrel 210 ℃, fourth barrel 210 ℃, fifth barrel 210 ℃, six barrel 180 The seventh barrel was 170 ℃, and the screw was rotated at 45 ~ 50rpm.

The twin-screw extruder used in this example was equipped with a mixing device as shown in FIG. 2, and was introduced into the hopper without separately mixing the rubber powder and the Soviet accelerator.

First, the poor rubber gloves were ground to 50 to 2 mesh, washed with water and dried to remove impurities. 100 kg of this rubber powder and 60-100 g of zinc pentachloro thiophenolic acid were added to a hopper so that the mixture was fed into the twin screw extruder at 1 to 5 kg per minute, and mixed and extruded.

The rubber produced through the extrusion was cooled by immersion in water of about 25 ℃.

Experimental Example  One.

In order to analyze the chemical properties of the regenerated rubber obtained in Example 1, infrared spectroscopy (FT-IR), process gas chromatography (PGC) and thermogravimetric analysis (TGA) method Was used.

The results are as shown in Table 2 and FIGS. 4 to 7.

Chemical Properties of General General Natural Rubber Raw Materials division percentage PHR percentage PHR Sample STR-20 SMR-20 Polymer 96.12 100.0 95.92 100.0 NR base NR base Oil + Organics 3.01 3.13 3.23 3.37 Ash 0.88 0.92 0.85 0.89 Total 100.0 104.0 100.0 104.3

Chemical analysis result of recycled rubber according to the present invention division percentage PHR Sample Play rubber Polymer 96 100 NR base Oil + Organics 3 3 Ash One One Total 100 104

Compared with the properties of the rubber recycled according to the present invention as described above with the natural rubber (STR-20 and SMR-20) imported from Thailand and Malaysia, it was found that the quality is excellent enough to find no difference.

Claims (4)

a) preparing a rubber pulverized product by pulverizing a waste rubber product containing 50% by weight or more of natural rubber latex into 50 to 2 mesh;
b) zinc pentachloro thiophenolate, bis (2-benzamidophenyl) disulfide, zinc-2-benzamido thiophenolic acid preparing a mixture by mixing one or more Soviet accelerators selected from the group consisting of (zinc-2-benzamidothiophenolate) and pentachlorothiophenol;
c) the first section of 150 to 200 ° C, the second section of 180 to 250 ° C, the third section of 150 to 200 ° C and the two to four stress shear sections and the ratio of length and diameter (L / D The mixture was introduced into a twin screw extruder having 26 to 46, and desulfurized sequentially for 1 minute to 1 minute 30 seconds in the first section, 2 to 3 minutes in the second section, and 1 minute to 1 minute 30 seconds in the third section. Allowing the reaction to be carried out; And
d) Waste rubber recycling method by a continuous extrusion method comprising the step of cooling the desulfurized rubber produced in step c). The method of claim 1, wherein the USSR accelerator is 0.06 to 0.1% by weight based on 100% by weight of the crushed rubber. The biaxial extruder of claim 1, further comprising: a first section comprising a 1-1 section of 160 to 180 ° C and a 1-2 section of 170 to 190 ° C; A second section of 200 to 220 ° C; The temperature range of the third section of 170 to 190 ℃, the stress shear section is located between the 1-2 section and the second section and between the second section and the third section, the ratio of length and diameter (L / D) is a coaxial twin-screw extruder of 28 to 32.
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