CH622539A5 - Process for improving the rheological properties of a hydrocarbon of the asphalt type - Google Patents

Description

The present invention relates to a process for improving the rheological properties of an asphalt type hydrocarbon by incorporating an organic polysulfide formed by the action of molten sulfur on a compound carrying a thiol group (-SH) in the rest of alcohol from an ester. The process according to the invention is characterized in that this compound is a polyester polythiol derived from an aliphatic polyacid, containing 2 to 5 carboxylic groups and at least 15 carbon atoms in its molecule.

The acids, which can enter into the composition of sulfur polyesters, are saturated or unsaturated aliphatic acids, carrying at least two carboxylic functions, and generally 2 to 5 -COOH groups, the total number of carbon atoms of the polyacid 55 being d 'at least 15. Preferably, the polyacids used are C5 to C66. They can consist of long chain acids, obtained by the gentle oxidation of paraffins and / and olefins. Thus, it is possible to use, for example, tetradecane dicarboxylic and tetracarboxylic acids, hexadecane-dicarboxylic, tricarboxylic or tetra-carboxy-Iic acids; other examples are di, tri, tetra, or penta-carboxylic acids derived from octadecanes, eicosanes, tri-acontanes, nonadecane-dicarboxylic, tetracosane-dicarboxylic, tricarboxylic, tetracarboxylic, or / and penta-carboxylic, f> 5 hexadecene -dicarboxylic, dicarboxylic octadecadienes, tricarboxylic octadecatrienes, etc.

A class of polyacids, which fall into the above series

in which R is an alkylene radical, most often in Cs to C12 and moreover in C2 to C6; R 'is a hydrogen atom or an aliphatic hydrocarbon chain, which may contain one or more double bonds and, optionally, substituents of the sulfo, nitrile, hydroxy type, etc. ; R "is an alkenyl chain which can carry, like R ', double bonds and / or substituents, but R" may not exist; the degree of polymerization n is generally low, not exceeding 10 or better not exceeding 6; most often n is equal to 2 or 3, that is to say that the polyester-polythiol is a dimer or a trimer of the unitary thiol ester, represented in the brackets of formula (1).

The hydrocarbon chains R 'or / and R "can form rings, in the molecule of the oligomer, as currently accepted for the dimer of linoleic acid for example (Journ. Amer. Org. Chem. Soc. - December 1962 - vol. 39 -page 535).

As indicated above in other words, the unitary acid group R'-CH = CH-R "-COO, in formula (1) generally contains up to 30 carbon atoms, but especially 6 to 24 and preferably 11 to 18.

Particularly useful products, which are both readily available industrially, are derived from various natural fatty acids, especially Clg, in particular oleic, elaidic, linoleic, linolenic, ricinoleic acids, etc. For exemple,

for oleic acid, that is to say octadecene-8-carboxylic acid that-1, R 'is CH3- (CH2) t-, the overall formula being thus:

[CH3- (CH2) 7-CH = CH- (CH2) 7-COO-R-SH] n

(2)

In the case of the dimer (n = 2), the structure of the corresponding dithiol diester can be written:

CH3- (CH2) 7-CH = C- (CH2) T-COO-R-SH CH3- (CH2) 7-CH2-CH- (CH2) T-COO-R-SH

(3)

The hydrocarbon group r, connecting the carboxyl to the thiol (-sh) function, can be linear or branched, for example ethenyl, propenyl, iso-propenyl, butenyl, iso-butenyl, hexenyl, oc-tenyl, iso-octenyl etc. Thus, for example, the -coo-r-sh end groups of the oligomers according to the invention can be:

-coo-ch2ch2sh -coo-ch2ch2ch2sh -coo-ch2-c h-sh

CH,

3

622,539

-COO-CH, -C H-CH-.SH I

ch3

-COO- (CH2) 6-SH etc.

As regards the polyester polythiols obtained from the monomeric polyacids, their structure is similar to that of the oligomers. We have for example:

HS-CH, OHU-OOC-CTLCTL-CH2-CH- (CH2) I0-COO-CH2CH2SH

I

COO-CH2CH2SH

in the case of an ethylene thiol triester of a heptadecane tricarboxylic acid.

The polyesters polythiols combine easily with elemental sulfur, to give corresponding polysulphides, useful as plasticizers of various materials, in particular bitumen, of which they improve the cohesiveness and the adhesion with respect to mineral fillers, including gravel. These polysulfides have a composition similar to that of the polyester polythiols described above, in which the hydrogen of the -SH groups reacted with the added sulfur, to give H 2 S and polysulfide groups, according to the well known reaction of training of the latter. The polysulphides obtained have a variable structure according to the temperature at which the operation is carried out, and according to the quantity of sulfur used. Thus, the S content of these polysulfides is from 1 to 10 S atoms per carboxylic group -COO present in the molecule, which corresponds to polysulfides of rank 2 to 20 in S. The most common products contain 2 to 6 S atoms per carboxylic group.

A process which can be used for the production of the polyester polythiols described above consists in esterifying, with a mercapto-alkanol, the chosen aliphatic polyacid. The operation can be carried out in a liquid, such as benzene for example, giving an azeotropic mixture with the water formed by the esterification; the water is thus removed by distillation, as the polyester is formed.

Depending on the nature of the polyacids and that of the mercapto-alkanols used, the temperature of the esterification can vary, but it is generally of the order of 50 ° to 150 ° C, and preferably from 70 ° to 100 ° C. As in other esterifications, it is advantageous to add an acid catalyst, in particular an aryl sulfonic acid.

The various acid oligomers which can be used can be represented globally by the formula:

(4)

35

[R'-CH = CH-R '' -COOH] „

(5)

in which R ', R "and n have the same meanings as above, with regard to formula (1).

At present, there are commercially available oligomers - mainly dimers and trimers - of unsaturated fatty acids, especially C 18, which are perfectly suitable for carrying out the present invention. These are for example the polyacids sold under the name "EMPOL" by the Unile-ver-Emery N.V. Company of Gouda (Holland). Such oligomers of unsaturated fatty acids are also described by Norman O.V. 55 SONNTAG in “INTERSCIENCE” vol. 5 under the title "Fatty Acids" on pages 3572-3580.

As for the mercapto-alkanols, various HO-R-SH compounds can be used, the group R of which is defined above, with regard to formula (1) and in the paragraph following the 6o formula (3). Thus, can the unsaturated polyacid be esterified using mercapto-ethanol, mercapto-propanol (or isopropa-nol), mercapto-butanol (or isobutanol), mercapto-octanols, etc. Mercapto-ethanol is particularly interesting.

Moreover, several different mercapto-alkanols can “be used jointly, to form mixed polyesters-poly-thiols, mixed. Likewise, can it be advantageous to use co-oligomers of different monomeric acids,

as is the case of the oleic-linoleic co-dimer described by J.C. COWAN in vol. 39 of Journ. Am. Org. Chem. Soc. (Dec. 1962) cited above, page 537.

The transformation of polyester-polythiols into polyester-polysulphides can be carried out by heating with elemental sulfur. Although this operation can take place in a fairly wide temperature range, in particular between 50 ° and 250 ° C, it is preferably carried out above the melting point of sulfur, in particular between 120 ° and 200 ° C. When polyester polythiols are derived from unsaturated fatty acids, in Q! at C24, in particular in Clg, their sulfurization is advantageously carried out between 150 ° and 200 ° C. As in other sulfurizations of organic compounds, it is advisable to incorporate into the reaction mixture an appropriate catalyst; such catalysts, known per se, are for example derivatives of guani-dine, in particular diphenyl-guanidine or the like.

The polysulphides described above are used, according to the invention, to improve the rheological properties of a heavy hydrocarbon, of the asphalt type.

A very useful application of these products is the production of coatings, sealants, seals and similar articles, based on hydrocarbon materials such as asphalt, tar, pitch, bitumen, etc. A small addition of these poly-ters-polysulfides, for example from 0.2 to 7% by weight, can be used to very significantly improve the rheological, mechanical and thermal properties of such coatings.

It is especially the polyesters-polysulphides, described above, in particular those which are obtained from dimeric and trimeric acids of unsaturated fatty acids, called "Empol", which are particularly suitable as an adjuvant for bituminous compositions; they have an elastomeric character due to the trimers contained in these acids, which have played the role of crosslinker. This mixture of dimer and trimer acids, readily available commercially, is therefore particularly advantageous, since there is no need to add an additional crosslinker in the bituminous medium.

The polyesters-polysulphides in question in particular give the bitumen considerably increased flexibility, allowing folding without breaking at -50 ° C; on the other hand, they improve cohesion, impact resistance and adhesiveness. These products also have the advantage of not crystallizing in bituminous compositions. Although the polyester polythiols described, themselves, can serve as adjuvants to bituminous compositions, their main utility is to serve as starting material for the preparation of the corresponding polysulphides.

Example a) Preparation of unsaturated polyester-polythiol oligomer

The preparation is carried out from a mixture of oligomers of fatty acids in Clg, known in the trade under the name EMPOL 1024 (Company UNILEVER-EMERY N.V.); this product contains, by weight, 81% of dimer of aliphatic acid unsaturated with 18 carbon atoms, the dimer thus being in C36; the remaining 19% is made up of the corresponding quarter (ie C54); there are only traces of monomeric acid; the acid number is 195; average molecular weight 620.

622,539

1140 g of these oligomers (1.83 moles) are mixed with 312 g of mercapto-ethanol (4 moles) in 1500 ml of benzene containing 10 g of benzene sulfonic acid as an esterification catalyst. The mixture is placed in a 4-liter reactor, equipped with an agitator and a descending coolant, for the distillation of the azeotropic mixture which forms benzene with the water coming from the esterification.

The contents of the flask are heated for 6 hours, distilling the benzene-water mixture / azeotrope as it is formed. 72 g of removed water are thus collected (4 moles).

The product, remaining in the reactor, is washed twice with 1 liter of water, after which the residual benzene is removed by distillation.

1280 g of unsaturated polyester-polythiol oligomer are thus obtained with the following characteristics:

acid number 16 SH% 7.9

iodine index 91 S% 8.7

saponification index 202

Analysis shows that 88.5% of the total sulfur present is in the form of a thiol group (-SH).

b) Preparation of unsaturated polyester polysulfide.

A1000 g of unsaturated polythiol polyester, obtained in the manner described in Example 1, 150 g of sulfur flower are added, and the mixture is heated to 180 ° C. with stirring, until cessation of release of H2S , or for 2 hours. 1110 g of product are obtained.

The elastomeric mass thus obtained has the following characteristics:

SH% close to 0

S% 17.9% or 1.97 S atoms per group -COO

glass transition temperature - 60 ° C

c) Preparation of a polysulphide concentrate in bitumen.

A preparation similar to that according to b) is carried out within a certain amount of bitumen, so as to obtain a polysulphide concentrate, with a view to its addition to bitumen masses for road surfaces.

For this, 300 g of unsaturated polythiol polyester, from Example 1, are introduced, with 50 g of sulfur, into 650 g of 80/100 penetrating bitumen; 1 g of diphenyl-guanidine, accelerator of the sulfurization, is added thereto. The whole is heated 180 ° ± 5 ° C for 2 hours, with stirring. The release of H2S having then greatly decreased, the product is cooled to room temperature; it is in the form of a viscoelastic mass, soluble in bitumen, tar, as well as in chlorinated aromatic solvents. This mass consists of a solution of polyester-polysulfide in bitumen, containing by weight 34% of polysulfide with 66% of bitumen; it has a glass transition temperature Tg of —58 ° C.

The thermal stability of this product is determined by heating at 200 ° C for 3 hours: the weight loss, following this test, is negligible. There is therefore a better stability even than with the good adjuvants based on polysulphides, described in French patents n ° 69 10935 and 70 41788.

d) Influence of polyester-polysulfide on the glass transition temperature (Tg)

On a series of samples, formed by diluting the concentrate to 34% obtained according to c) in variable quantities of fresh bitumen of penetration 80/100, the Tg were determined in the known manner, the following results were obtained:

% by weight of polysulphide 34 13.6 10.2 6.8 1.70 in bitumen

Tg ° C -58 -45 -35 -34 -22

It can be seen that the addition to the bitumen even of a small proportion of polysulphide, according to the invention, makes it possible to very significantly lower the glass transition temperature, which indirectly gives the measurement of the resistance to bending.

e) Application to aggregate compositions, with bitumen

The polysulfide concentrate obtained according to c) is used for the preparation of a composition of 100 parts of pebbles and gravel (“Vignat aggregate”) with 6.6 parts of bitumen penetrating 80/100. The latter contains 6.8% of polysulfide described under b). Test pieces of this composition are subjected to stability determinations, by the known Duriez and Brazilian methods, described in particular in publication No. 2,036,843 of French Patent No. 69,10935, pages 7 and 8, and in "New Treaty of Building Materials" volume III - DUNOD 1962, p. 681.

Similar test pieces, the bitumen of which, however, contains no additives, are subjected to the same tests. The following results are found:

Stability DURIEZ 1mm kg / cm2

Composition

Composition

next to bitumen

the invention without adjuvant

0 ° C 18 ° C 50 ° C

0 ° C 18 ° C 50 ° C

Immediate

168 110 12

121 62 10.6

After 7 days

198 133 14

135 67 12.6

After 7 days

with imbibition

207 140 14.5

127 59 5.8

Brazilian stability

1mm kg

Composition

Bitumen composition

according to the invention without adjuvant

0 ° C

18 ° C

50 ° C

0 ° C

18 ° C

50 ° C

Immediate

3053

2000

138

2300

1250

116

After 7 days

3567

2310

142

2670

1425

183

After 7 days

with imbibition

4133

2780

189

2620

1250

101

It can be seen that at equal temperatures the stabilities of the aggregates containing polysulfide according to the invention are considerably higher than those of similar bituminous aggregates, without additives.

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Claims (9)

622,539 2 1. Process for improving the rheological properties of a heavy hydrocarbon of the asphalt type by incorporation of an organic polysulfide, formed by the action of molten sulfur on a compound carrying a thiol group (-SH) in the alcohol residue j an ester, characterized in that this compound is a polyester polythiol derived from an aliphatic polyacid, containing 2 to 5 carboxylic groups and at least 15 carbon atoms in its molecule. 2. Method according to claim 1, characterized in that m the polyacid of the polythiol polyester is C15 to C66. 3. Method according to claim 1 or 2, characterized in that the polyacid of polyester polythiol is unsaturated, its molecule containing one to three double bonds. 4. Method according to claim 3, characterized in that the polyacid is an oligomer of an unsaturated C3 to C24 acid and more particularly in Cn to C18, the degree of polymerization of this monomeric acid does not exceed 10, and is generally 2 or 3. 5. Method according to claim 4, characterized in that the polyacid is a dimer or trimer of an unsaturated fatty acid, from the series of oleic, elaidic, linoleic, linolenic and ricinoleic acids. 6. Method according to one of claims 1 to 5, characterized in that the polysulfide, formed from the polythiol polyester, contains 1 to 10 sulfur atoms per carboxylic group present. 7. Method according to one of claims 1 to 6, characterized in that the proportion of polysulfide is 1.7 to 34% by weight of the heavy hydrocarbon. 30 8. Method according to one of claims 1 to 6, applied to bitumen for roads, with a view to improving the stability of compositions of bitumen with pebbles and gravel, characterized in that the proportion of polysulfide is from 0.2 to 7 % by weight of bitumen. 35 9. Method according to one of claims 1 to 8, characterized in that the transformation of the polythiol polyester into polysulfide, by reaction with sulfur, is carried out by heating within a portion of heavy hydrocarbon of the asphalt type. indicated, consists of oligomers of unsaturated aliphatic acids. These polyacids can be derived from different ethylenic acid monomers which may contain up to 30 carbon atoms or more. For practical uses, polyesters-polythiols based on fatty acid oligomers, unsaturated, C6 to C24 and especially Cu to Clg, are particularly suitable. The monomeric acids entering into the composition of these polyesters poly-thiols, must contain at least one double bond, but they can advantageously comprise several, as it is, for example, the case of linoleic acids (octadecadiene-carboxylic) ) or linolenic (octadecatriene-carboxylic). On the other hand, these acids can carry other groups, such as nitrile, sulfo etc. and, more particularly, -OH, as for example in ricinoleic acid. Unsaturated polythiesters of this particular class correspond to the general formula: [R'-CH = CH-R '' -COO-R — SH] n (1)