FI67719B - FOER FARING MODIFICATION AV BITUM - Google Patents

Description

6771 9

Method for modifying bitumen

The invention relates to the modification of the properties of blown bitumen by reaction with diisocyanates.

The properties of the blown bitumen, such as softening and viscosity properties, can be significantly altered by treating the bitumen with a diisocyanate, preferably polymeric diphenylmethane-4,4'-diisocyanate, at a temperature well above the softening point.

10 Bitumen means a solid or semi-solid product, mainly hydrocarbons, soluble in trichlorethylene and made from petroleum or naturally derived from asphalt. Today, the main method of bitumen production is petroleum distillation.

Petroleum-based bitumens are divided into two main categories: tis-15 charged bitumens and blown bitumens. Distilled bitumens generally have a lower softening point and a higher breaking point than blown bitumens, with the same penetration. Blasting of bitumens produces bitumens whose viscous properties do not change as much with varying temperature as distilled bitumens. Distilled bitumens are widely used as a binder in road pavements, while blown bitumens are used in water and moisture insulation as well as in the roofing felt industry.

The following table shows the properties of some distilled and blown bitumens:

Distilled bitumens Blown bitumens

Marking_B-45 B-65 B-80 B-120 B-85/40 B-95/35 B-100/40

Penetration x) 30 (0.1 nm; 25 ° C) 35 ... 50 50 ... 70 70 ... 100 100 ... 145 35 ... 50 25 ... 40 35 ... 50 XX )

Softening point (ring-ball method; ° C) 56 52 48 44 80 ... 90 90 ... 100 95 ... 105 X) ASTM D 5-73 XX) ASTM D 36-76 6771 9

Bitumen blowing is performed by blowing air through hot bitumen, whereby the hydrocarbons of the bitumen dehydrate and then polymerize. The oxygen in the air forms with the released hydrogen water, which leaves the blast-5 gases with the column. It is likely that the blowing also produces oxygen-containing groups that can react with the isocyanate to form polymers. Thus, it is conceivable that the softening and viscosity properties of blown bitumen could be altered by isocyanate.

The softening point is the most important quality requirement for blown bitumens and the classification of species is therefore primarily based on it. The general aim is for the bitumen to have a softening point at least 30 ° C higher than the maximum application temperature. In the present invention, it is essential that the softening point of blown bitumens can be significantly increased with small (0.1 to 2%) amounts of diisocyanate. Viscosity properties also change, viscosity increases. Treatment with di-20 isocyanate is most safely and efficiently performed using polymeric diphenylmethane-4,4'-diisocyanate (MDI) or a derivative thereof, as isocyanate resistant to temperatures above 100 ° C is required.

The formula of said diisocyanate is

30 “CH2 ~ n“ lX ^^ VR

wherein R = H or lower alkyl.

Penetration, the second quality-35 classification mark for blown bitumens, becomes slightly smaller during processing.

6771 9

It is previously known (U.S. Pat. No. 3,650,791) to treat a mainly distilled bitumen used as a binder for coatings with a diisocyanate having a number of carbon atoms between 6 and 18, mainly toluene di-5 isocyanate (TDI). In this case, for example, a 1% increase was found to cause an increase in the softening point of about 5 ° C (column 3-4, Table III). Instead of using polymeric MDI (1% Desmodur 44 V 20, Bayer, 1 hour 130 ° C) for the treatment of blown bitumen according to the invention, the changes in softening point were greater. It should be noted that when a similar treatment was applied to distilled bitumens B-65, B-120 and B-300, no change was observed with B-300 and the changes were also small with B-65.

The following table shows the results obtained with blown bi-15 cores after addition of polymeric MDI (Desmodur 44 V 20, Bayer) and stirring for 1 hour at 170 ° C.

% 6771 9 in \ m m ^ r- m o - T- r— o r- ο χ- Ι ffl o id m T-

1— O (N

o oo no -CM CM Γ-

O CM t— O

* 3 ·

OF

0 o o o o

O - CM CM O

T- r— CM

1 Λ

OQ

m T- σ o - n is o r- τ- Ο ιο r ~~ id η σ το n cm ο

- CM T— CM

CM I- r- in n ο 'τ σ o in - cm o r- σ T- r- τ- Ι

PQ

_ in r- n in H - cm ο * · 3 ° 2 o cm n n β η σ »-

B

Or- ΙΟ O

- η σ cm o r- * 3 · \ in 00 in oo 1 - n Orff) o ο σ in oo n oo "x I * • p Q) 4j ^ 4j - · ni" -PX CO IO -rl Λ ^ 'nJ' '• HfOO -PCD L ^ 2 mo U Οι h + j to mn • pc - -ho to 2 - q) -h _ ^

2 in # U ΙΛ · Η 5 ad 0) 0 UQ

3> 1 - '(OCMg ^ g-POi «

rH 10 rtj. - φ | .Η · Ρ f · S

• H OWS-lgCWiDM-- .¾, ¾ S to> i -P g QJIO + J OU “2 w 3 -Hiitd) εεηφΛίο

-P I 10 G r ~ X! C 2 W O

• Η -Η -Η φ - φ φ φ -H r- - ff> Q r-l Ot ^ Q, ffi U, g> <r ^ »X x

X

5 6771 9

The diisocyanate treatment clearly improved the heat resistance (assay: a drop of bitumen was placed on a sheet metal plate, the plate was placed in an oven, the temperature was raised and the flow temperature of the bitumen was determined; cf. SFS 2428 (5011)). Thus, for example, grades 95/35 and 100/40, in which the diisocyanate addition was 2%, no run-off had yet occurred at 150 ° C, when it was at 90 ° C as such for said grades. The cold bending properties were not significantly altered by the addition of diisocyanate, the tensile strength increased slightly and the elongation decreased slightly. It is also expected that the tendency of bitumen to age will decrease as the reactive groups become at least partially bound by diisocyanate treatment.

Treatment of blown bitumen with polymeric MDI or a derivative thereof requires that the bitumen 15 be easily mixed, i.e. the temperature should be at least 20 ° C higher than the softening point of the pure bitumen. In this case, the reaction time becomes long. It has been found that a temperature of 170 ° C is suitable for blown bitumens, but higher temperatures can be used.

Claims (4)

6771 9 A process for modifying the softening and viscosity properties of blown bitumen, characterized in that it is treated with a diisocyanate such as polymeric diphenylmethane-4,4'-diisocyanate or a derivative thereof. Process according to Claim 1, characterized in that the diisocyanate is polymeric diphenylmethane-4,4'-diisocyanate (MDI). Process according to Claims 1 and 2, characterized in that the amount of diisocyanate is 0.1 to 5% of the amount of blown bitumen. Process according to Claims 1 to 3, characterized in that the reaction takes place at least 20 ° C, preferably 50 to 100 ° C, above the softening point of the blown bitumen. Il