JPS587641B2 - How to recycle waste rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for effectively recycling waste rubber such as waste tires.

In recent years, with the remarkable development of motorization, the amount of discarded used tires has also increased rapidly, and the disposal of them has become a problem.

Up until now, the methods of disposing of waste tires include reuse in their original form, landfilling,
Incineration has been carried out as an emergency measure, but it cannot be said to meet social demands such as prevention of environmental pollution and effective use of resources.

Two methods have been studied for a long time: one is to desulfurize waste rubber to obtain recycled rubber, and the other is to thermally decompose waste rubber under chemicals to recover oil or carbon black. From the perspective of effective use of resources, this is something that should be actively developed in the future.

However, when comparing the energy required to obtain the desired product for the former two methods, considering that the difference between the two methods is the degree to which the chemical bonds in the waste rubber are broken, the former is better. The latter should consume less energy than the latter.

In the past, a variety of methods have been proposed for recycling waste rubber, but most of them require high temperatures of 150°C or higher and are difficult to implement unless you have special equipment for that purpose. I couldn't do it.

Furthermore, most of the conventional recycling methods were developed for natural rubber, and rubber containing a large amount of synthetic rubber could not be effectively recycled.

The object of the present invention is to provide a new method for recycling waste rubber that overcomes these drawbacks.

The present invention uses waste rubber as (a) a benzenesulfinic acid derivative;
(b) at least one compound selected from Group I consisting of a benzenesulfonyl hydrazide derivative, (C) sulfur dioxide, (d) aromatic disulfide, and (e) thiuram monosulfide or thiuram disulfide. , and (f) DBU or its salts, and (g)
The gist of the present invention is a method for recycling waste rubber, which comprises kneading it with at least one amine compound selected from Group 1 consisting of aliphatic amines or alicyclic amines.

The present inventors have already used the compounds (a), (b), and (e), thiuram disulfide and ge), each alone, and the compounds (e) and (f) in combination. We have discovered that it exhibits excellent regenerative effects by doing so, and we are currently applying for a patent.

However, subsequent research revealed that combinations other than the above (a)
~(e) i.e. at least one selected from group ■
The present invention was achieved by discovering that the regeneration effect is synergistically increased when these compounds are used together with at least one amine compound selected from Group I (f) and (g), that is, at least one amine compound selected from Group I.

According to the method of the present invention, it is possible to effectively perform regeneration at room temperature, which was difficult with conventional methods.

Further, according to the method of the present invention, equipment such as a roll kneader, Brabender, Banbury, Recremeter, etc. normally owned by those engaged in the rubber industry can be used as is.

Furthermore, according to the present invention, not only natural rubber but also waste rubber containing a large amount of synthetic rubber, which has been difficult to regenerate using conventional methods, can be effectively recycled.

Furthermore, the recycled rubber obtained by the method of the present invention exhibits better performance than recycled rubber obtained by conventional methods.

The present invention will be explained in detail below.

The regenerating agent that can be used in the present invention is a combination of at least one compound selected from the above Group (1) and at least one amine compound selected from the above Group I.

Group ■ is (a) a benzene sulfinic acid derivative represented by the general formula (where X is one selected from H, Li, Na, and K) (b) a benzene represented by the general formula Sulfonyl hydrazide derivatives (wherein (a) and (b) R1 and R2 are H,
CH3, C2H5, C3H7, C4H9) (c) sulfur dioxide (d) aromatic disulfide; and (e) thiuram monosulfide or thiuram disulfide represented by the general formula (wherein and n is an integer of l or 2, R3, R4, R
5 and R6 are hydrocarbon groups having 1 to 6 carbon atoms, such as aliphatic groups, alicyclic groups, or aromatic groups, and R3 and R4 and/or R and R6 may form a ring. Group I consists of each component of (f) 1
・8-diazabicyclo[5.4.O]unthecene-7(
(hereinafter abbreviated as DBU), phenol salts of DBU or carboxylic acid salts of DBU, and (g) aliphatic amine or alicyclic amine.

The benzenesulfinic acid derivative of component (a) includes benzenesulfinic acid, p-toluenesulfinic acid,
Alkyl-substituted or unsubstituted benzenesulfuric acids such as 0-toluenesulfuric acid, lithium benzenesulfinate, sodium benzenesulfinate, potassium benzenesulfinate, lithium p-toluenesulfinate, p-toluene Sodium sulfinate, sodium p-toluenesulfinate, potassium p-toluenesulfinate, sodium p-toluenesulfinate, p
Examples include alkali metal salts of alkyl-substituted or unsubstituted benzenesulfinic acids, such as sodium monoethylbenzenesulfinate, sodium ethylbenzenesulfinate, and sodium 2,4-dimethylbenzenesulfinate.

Among these, benzenesulfinic acid, p-toluenesulfinic acid, sodium benzenesulfinate, and sodium p-toluenesulfinate are preferred.

Component (b) benzenesulfonylhydrazide derivatives include benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, o-toluenesulfonylhydrazide, p-ethylbenzenesulfonylhydrazide, o-
Examples include ethylbenzenesulfonyl hydrazide and 2,4-dimethylbenzenesulfonyl hydrazide.

Among these, benzenesulfonyl hydrazide and p=toluenesulfonyl hydrazide are preferred.

Note that free conductors such as sulfonic acid, sulfonyl chloride, sulfonamide, and ester of sulfonic acid having a structure similar to component (b) have no regeneration effect.

The component (C), sulfur dioxide, also has a regenerating effect, but sulfur dioxide remains a gas at room temperature and is inconvenient to handle, so it must be used by reacting with a Group I amine compound in advance or by absorbing it in excess amine compound. is desirable.

As the aromatic disulfide of component (d), diphenyl disulfide, ditolyl disulfide, and dixyl disulfide are preferably used.

Examples of the thiuram monosulfide of component (e) include tetramethylthiuram monosulfide, tetraethylthiuram monosulfide, tetraprobylthiuram monosulfide, tetrabutylthiuram momesulfide, and tetrapentylthiuram monosulfide. Examples of thiuram disulfides include tetrahexylthiuram monosulfide, dipentamethylenethiuram monosulfide, and tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetraprobylthiuram disulfide. ,
Tetrabutylthiuram disulfide, tetrapentylthiuram disulfide, tetrahexylthiuram disulfide, dipentamethylenethiuram disulfide, N-N
'-Siethy-N-N-diphenylthiuram disulfide.

Other examples of thiuram monosulfide and thiuram disulfide include those in which the four hydrocarbons of the above compounds are interchanged.

Among component (e), thiuram disulfide has a more remarkable regenerating effect.

Similar compounds include thiuram polysulfides such as thiuram trisulfide and thiuram tetrasulfide, but when used in combination with Group I amine compounds, a certain degree of regeneration effect was observed, but thiuram monosulfide and thiuram polysulfide It does not have the same regenerative effect as thiuram disulfide.

Group I components (f) include DBU and its phenolic and carboxylic acid salts.

Phenol salt of DBU as phenol salt of DBU,
Examples include cresol salts, resorcinol salts, hydroquinone salts, and the like.

DBU carboxylates include DBU formate, acetate, propionate, n- and iso-monobutyrate, n- and iso-monovalerate, neopentanoate, caprylate, enanthate, 2- Ethylhexylate, pelargonate, cabrate, neodecanoate, undecanoate, laurate, tridecylate, myristate, pentadecylate, palmitate, heptadecylate,
stearate, nonadecanoate, arachate, behenate, lignocerate, cerotate, heptacosanoate, montanate, melisinate, lacerate,
Acrylate, methacrylate, crotonate, incrotonate, undecylenate, oleate, elaidate, cetraate, erucate, brassidate, sorbate, linoleate, linolenic acid acid salt, arachidonate, propiolate, stearolate,
Saturated or unsaturated aliphatic carboxylates such as oxalate, succinate, adipate, cetacean oleate, shark oleate,
Examples include aromatic carboxylates such as benzoates and toluates, and resinates such as rosin salts and tall oil salts.

Among these, particularly preferred are DBU, phenol salts of DBU, cresol salts, and aliphatic carboxylates having 1 to 10 carbon atoms.

Another component (g) belonging to group I is an aliphatic or cycloaliphatic amine.

Preferably these are primary, secondary and tertiary amines having 1 to 10 carbon atoms.

Specific examples include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, probylamine, dipropylamine, triprobylamine, butylamine, dibutylamine, tributylaminepentylamine, dipentylamine, tripentylamine, hexylamine, Examples include dihexylamine, trihexylamine, cyclohexylamine, dicyclohexylamine, morpholine, piperazine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and triethylenediamine.

It is desirable to use the regenerating agent of the present invention in an amount that allows effective regeneration and does not cause any abnormality in the revulcanization reaction of the recycled rubber.

Among the regenerants according to the present invention, DBU, its salts, and thiuram mono- or disulfide all have the function of promoting vulcanization, so their use in excess often makes it difficult to control the vulcanization reaction.

From this point of view, the respective compounds belonging to Groups I and I are usually used in amounts of 0.05 to 100 parts by weight per 100 parts by weight of waste rubber.
About 5 parts by weight is used.

Among these, effective regeneration and revulcanization reaction are carried out in the range of 0.1 to 2 parts by weight.

In the present invention, compounds selected from Group I and compounds selected from Group I must be used in combination.

The ratio of the combination is the number of moles of (a): the number of moles of (b) - l:9
-9:l, but especially in the range of l:3 to 3:l, a great regeneration effect can be obtained.

In the present invention, the regenerant is preferably used together with oil.

Even if the regenerating agent of the present invention is used alone, regeneration will not fail, but it will be insufficient.

On the other hand, when oil is used in combination, a great regeneration effect can be obtained.

The vine oil used in the present invention may be any softening oil or recycled oil used in the rubber industry.

For example, paraffinic, naphthenic, or aromatic process oils, high-boiling oils such as petroleum asphalt and coal tar, and vegetable oils such as tall oil, rosin, pine tar, and dipentene can be used.

The larger the amount of oil used, the more effective it is for regeneration.

However, since excessive use deteriorates the performance of recycled rubber, it is usually 1 to 40 parts, preferably 5 parts per 100 parts of waste rubber.
~20 parts are used.

Recycling of waste rubber is carried out by kneading the waste rubber with the regenerating agent according to the present invention, preferably with the addition of the above-mentioned oil.

It is better to perform the kneading at the lowest possible temperature of 120° C. or below for better workability and greater effectiveness.

The kneading time varies depending on the required degree of plasticity, but is usually 5 to 6 minutes.
Sufficient plasticization can be achieved in a time of 0 minutes.

As the kneading device, a roll, 21-dar, Brabender, Banbury, Recremeter, etc. can be used.
Regeneration can be performed particularly effectively when a roll is used.

The effect of kneading can be further enhanced by narrowing the clearance.

Rubber recycled by the method of the present invention can be reused as a raw material for tires, belts, hoses, sheets, packing, etc., either alone or in combination with new rubber.

The present invention will be explained in more detail with reference to Examples below.

In the examples, the plasticity used as an index of the degree of regeneration was determined using a Rapid Plastymeter manufactured by Wallace at a temperature of 100°C and a load of 12.7k9/cm.
Measured under the condition of cm2.

The smaller this value is, the greater the plasticity is, and a value of 70 or less is practically desired.

The parts in the blending ratio are parts by weight.

Example l 30 mesh powder rubber obtained from waste passenger car tires (about 65% natural rubber, about 35% styrene-butadiene rubber) 1
00 parts, p-toluenesulfinic acid 1.0 parts (6.4 mmol per 1005' of powdered rubber), di-n-butylamine 1.0 parts (7.8 mmol per 100fI of powdered rubber)
and 10 parts of process oil were mixed in a suitable container.

This mixture was transferred onto a roll maintained at 40 to 60° C. with a narrow gap and passed through repeatedly, and the powdered rubber immediately became a sheet.

This sheet initially had poor plasticity and still retained elasticity, but the plasticity increased rapidly during continued kneading.

After 30 minutes, the rubber sheet was collected from the roll. When the plasticity of the rubber sheet thus obtained was measured, a value of 39 was obtained, indicating that the regeneration was effectively carried out.

Further, in the same manner as above, 1.0 part of p-}luenesulfinic acid/and 1.0 part of DBU per 10 parts of waste rubber was added as amine. O
1.6 parts of phenol salt of DBU or 1.9 parts of 2-ethylhexanoate of DBU (10 parts of powdered rubber, respectively)
Experiments were also conducted using 6.6 mmol/0y).

The measurement results of the plasticity are shown in Table 1, and it can be seen that effective regeneration was carried out in all cases.

Comparative Example 1 In order to find out the effect of using each of the above two regenerants alone without combining them, 100 parts of the powdered rubber used in Example 1, 10 parts of the process oil, and each regenerant were used. The same treatment as in Example 1 was carried out using twice the amount of agent used in Example 1.

Furthermore, experiments were also conducted in the case where no regenerant was used.

According to the plasticity measurement results listed in Table 2, di-n-butylamine has almost no regenerative effect, but p-toluenesulfuric acid, DBU, and their salts have a certain degree of regenerative effect. .

However, these effects are also compared to the effects of Example 1.
Since it is quite small, it is clear that the combined use of p-}luenesulfinic acid and the above-mentioned amines produces a synergistic regeneration effect.

Comparative Example 2 100 parts of the powdered rubber used in Example 1, 10 parts of process oil, 1.0 parts of p-toluenesulfinic acid, and 1,0 parts of pyridine or 1.0 parts of p-chloroaniline as an amine. The same treatment as in Example 1 was carried out using each sample.

The plasticity value was 69 for the system using pyridine and 56 for the system using p-chloraniline.

Since these amines have low basicity, p-}
It can be seen that the amine to be used in combination with luenesulfinic acid is preferably an amine with very high basicity, such as the aliphatic amine shown in Example 1 or DBUs.

Example 2 Powder rubber I was prepared using 100 parts of the powdered rubber used in Example 1, IO parts of process oil, and 1 and θ parts of di-n-butylamine.
per OOP) and 1.4 parts of sodium p'toluenesulfinate or benzenesulfonyl hydrazide i. t parts (each per 100f of powdered rubber, 6.
The same treatment as in Example 1 was carried out using 51 mol).

The plasticity of the obtained recycled rubber was 52 for the system using sodium p-}luenesulfinate and 46 for the system using benzenesulfonyl hydrazide, and effective regeneration was carried out in both cases.

Comparative Example 3 In order to know the regeneration effect when the regenerant of Example 2 was used alone without being combined with an amine, 100 parts of the powdered rubber used in Example 1, 10 parts of process oil, and p
-4 Using twice the amount of sodium luenesulfinate or benzenesulfonyl hydrazide as used in Example 2,
Similar treatment was performed.

The plasticity value was 60 for the former and 56 for the latter, and since neither regeneration effect was so large, it can be recognized that the effect of Example 2 used in combination with amine is a synergistic effect.

Comparative Example 4 100 parts of the powdered rubber used in Example 1, 10 parts of process oil, 1.0 parts of di-n-butylamine, and various benzenesulfonic acid derivatives listed in Table 3 were added to powdered rubber 1.
The same treatment was carried out using 6.5 mmol per 00 g.

The results are shown in Table 3, and the plasticity when these derivatives were used was 70 to 80, indicating no effect.

This shows that only alkali metal sulfinates and sulfonic acid hydrazide derivatives exhibit specific regenerative effects when used in combination with amines.

Example 3 100 parts of powdered rubber used in Example 1, 10 parts of process oil, 1.0 part of DBU (per iooy of powdered rubber,
6.6 mmol) and thiuram mono- or disulfide/or aromatic disulfide listed in Table 3, respectively, per powdered rubber ioof (however, thiuram compounds and aromatic odisulfides have two regenerations per molecule). It was calculated as having a function.

) was used to perform the same treatment as in Example 1.

The plasticity values of the obtained recycled rubber are listed in Table 4,
All values were 32 to 45, indicating that the regeneration was performed effectively.

Among these, the effects of thiuram disulfide in Examples 3-2 and 3-3 are particularly large.

Comparative Example 5 In order to know the regeneration effect when the regenerant of Example 3 was used alone without being combined with an amine, 100 parts of the powdered rubber used in Example 1, 10 parts of process oil, and Example 3 were used. Similar treatment was carried out using the same regenerating agent used in Example 3 in twice the amount used in Example 3.

According to the plasticity measurement results listed in Table 5, Comparative Example 5-
Although some examples showed quite good results, such as Examples 2 and 5-3, the results of Comparative Examples 5-1 to 5-4 were compared to Example 3-1 in Table 4.
When compared with the results of 3-4, it can be seen that Example 3 gives much better results.

Comparative Example 6 100 parts of the powdered rubber used in Example 1, 10 parts of process oil, 1 part of DBU, and 1.2 parts of dipentamethylenethiuram tetrasulfide (per powdered rubber too2,
6.5 mmol) was used, and the same treatment as in Example 1 was performed.

The plasticity in this case was 51, and Examples 3-1 to 3
The effect was smaller than the case of using thiuram mono and disulfide shown in -3.

Example 4 Crystals obtained by absorbing sulfur dioxide gas into 100 parts of the powdered rubber used in Example 1, 10 parts of process oil, and n-butylamine (consisting of 1 mole of n-butylamine and 2 moles of sulfur gas) ) Similar treatment was carried out using 1.3 parts.

Furthermore, an experiment was also conducted in which 1.0 part of DBU was used in place of n-butylamine to absorb as much sulfur dioxide gas as possible.

The plasticity values are 55 for the former and 36 for the latter, which indicates that n-butylamine and DBU alone have a plasticity value of 2.
Considering that the plasticity when using 0 parts is 77 and 44, respectively, it can be seen that the combination of sulfur dioxide gas and amine produces a synergistic regeneration effect.

Example 5 2 mm square scrap rubber obtained from waste truck and bus tires (
100 parts (based on natural com), 10 parts of process oil, 5 parts of p-toluenesulfinic acid, and 0.0 parts of DBU. 5
The same treatment as in Example 1 was carried out using
Recycled rubber No. 4 was obtained.

Next, this recycled rubber was compounded and vulcanized according to the method of JIS K6313 to create a slab sheet with a thickness of 2 mm, and the JIS hardness (Hd), strength at break (TB), and elongation at break (EB) were measured. did.

The results are: Hd=61, TB=170k9/cm2, EB
=360%.

Furthermore, in an experiment using 0.4 parts of tetramethylthiuram disulfide and 0.5 parts of DBU instead of the regenerant, the plasticity was 22, the physical properties were Hd=70, TB
=113k9/Cm2, EB=230%.

For comparison, commercially available recycled rubber from waste truck and bus tires was also compounded using the JIS K6313 method.
After vulcanization and measurement of physical properties, Hd=56, TB=74k
g/cm2, EB=310% was obtained.

It is clear from this that the vulcanized physical properties of the rubber recycled by the method of the invention are superior to those of commercially available recycled rubber from similar tires.

Example 6 2 mm square scrap rubber obtained from waste truck and bus tires (
80% natural rubber, 20% styrene butadiene rubber)
Example l
The mixture was kneaded for 30 minutes in the same manner as above.

The plasticity of the obtained recycled rubber was 46, and the physical properties were Hd=
58, TB=82 kg/cm2, EB=270%.

Also, an experiment was conducted using 0.08 part of tetramethylthiuram disulfide and 0.1 part of DBU instead of the regenerant, and the plasticity was 45 and the physical properties were as follows.
Hd=60, TB=102kg/cm2, EB=300
%Met.

Thus, it can be seen that the regenerating agent of the present invention exhibits a sufficiently large regenerating effect even in a small amount, and the physical properties of the recycled rubber are also excellent.

Comparative Example 7 100 parts of the same powdered rubber used in Example 1, 1.0 part of p-toluenesulfinic acid, and 1.0 part of DBU were mixed in a suitable container.

This mixture was kneaded for 45 minutes using a Brabender set at a temperature of 150° C., and then passed through a roll for 5 minutes to form a sheet.

The plasticity of this sheet was 36.

However, when only 2 parts of p-toluenesulfinic acid was used instead of the regenerant, the plasticity was 26.
It cannot be said that the combination of the above two types of regenerants produced a synergistic effect.

Moreover, when 0.7 part of tetramethylthiuram disulfide and 1.0 part of DBU are used instead of the regenerating agent,
No plasticization occurred.

Claims (1)

[Claims] 1. At least one waste rubber selected from group ■
and at least one amine compound selected from Group I: Here, Group II is (a) benzene sulfine represented by the general formula Acid derivative (wherein, R1 and R2 are H.
CH3, C2H5, C3H7, C4H, (e) sulfur dioxide, (d) aromatic disulfide, and (e) ram disulfide (where n is an integer of 1 or 2, R3,
R4, R5 and R6 are hydrocarbon groups having 1 to 6 carbon atoms, and R3 and R4 and/or R5 and R6 may form a ring) (f) 1.8-diazabisic group [5.4・0] Unthecene-7 (hereinafter abbreviated as DBU), phenol salts of DBU or carboxylic acid salts of DBU, and (g) consisting of each component of aliphatic amine or alicyclic amine, provided that Group ■ and Group I The combination of the above-mentioned ram disulfide and the component (f) is excluded. 2. The method for recycling waste rubber according to claim 1, wherein the kneading temperature is 120° C. or lower. 3. The compounding amounts of the Group I compound and the Group I compound are both 0.00% per 100 parts by weight of waste rubber.
The method for recycling waste rubber according to claim 1, wherein the amount is 05 to 5 parts by weight. 4. The method for recycling waste rubber according to claim 1, wherein the molar blending ratio of the compound of Group I and the compound of Group I is 1:9 to 9:1, 5. The waste rubber 1
2. The method for recycling waste rubber according to claim 1, wherein 1 to 40 parts by weight of oil are used per 00 parts by weight. 6. The waste rubber recycling method according to claim 1, wherein the kneading method is roll kneading. 7 The benzenesulfinic acid derivative of component (a) is benzenesulfinic acid, p-toluenesulfinic acid,
The method for recycling waste rubber according to claim 1, wherein at least one selected from sodium benzenesulfinate and sodium p-}luenesulfinate is used. 8 The benzenesulfonylhydrazide derivative of the component (b) is benzenesulfonylhydrazide and p-}
At least one selected from luenesulfonyl hydrazide
A method for recycling waste rubber according to claim 1, which is a seed rubber. 9. The method for recycling waste rubber according to claim 1, wherein the component (e) is thiuram disulfide; 10. The component (f) is DBU, DBU
The method for recycling waste rubber according to claim 1, wherein at least one selected from phenol salts of DBU, cresol salts of DBU, and aliphatic carboxylates having 1 to 10 carbon atoms of DBU is used.