Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-08-17
2004-03-30
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S059000, C524S070000
Reexamination Certificate
active
06713539
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to an asphalt composition and its preparation process. More particularly, it is related to a storage-stable polymer-modified asphalt composition and its preparation process.
DESCRIPTION OF THE PRIOR ART
Asphalt materials have rapidly developed as paving and decorating materials in the road and architecture sectors. However, the optimum performance properties of asphalt and its blend such as viscoelasticity, plasticity, adhesiveness, etc. can not exert since they are affected by many factors. Among various factors, climate is the most important one. In the season of high temperature, summer, ruts caused by racing vehicles on express highways are the major factor leading to the damage of the road surface. In winters, fractures on the road surface resulted from the abruptly change of the temperature are the major causes for the transverse crack. In the rain seasons in the south, the intrusion of the rainwater leads to the interaction of asphalt with the blend material at the interface, thereby lowering the adhesive performance of asphalt and making it easy for asphalt to strip from the stones. Therefore, it is necessary to improve the Theological property of asphalt. Addition of a polymer is an effective way to improve the performance of asphalt. Addition of a polymer can enhance the viscosity and high temperature resistance, lower the low temperature sensibility, and improve the low temperature performance at the same time.
Asphalt modified by olefin polymers is reviewed in T. F. Yen, et al.,
Asphaltenes and Asphalts, I Developments in Petroleum Science
. The amount of the polymers is 6 wt %, and the stability of asphalt modified by various polymers is shown in Table 1.
TABLE 1
Polymer type
None
APP
LDPE
EPDM
SBS
Penetration (25° C., 100 g,
133
145
41
50
72
5 s), dmm
Softening point
44
47
98
66
98
(ring-and-ball), ° C.
Stability
Top softening
—
55
>100
87
>100
test
point, ° C.
(163° C.,
Bottom softening
—
45
52
52
61
48 h)
point, ° C.
Softening point
—
10
>50
35
>40
difference, ° C.
It can be seen from Table 1 that when APP (atactic polypropylene), LDPE (low density polyactene), EPDM (ethylenepropylene-diene ternary copolymer), SBS (styrene-butadiene-styrene three-block copolymer) are added to asphalt respectively, phase separation takes place between most of the polymers and asphalt, thus directly affecting the performance properties of the asphalt-polymer compositions.
EP 639630A1 discloses a process for preparing stable asphalt-polymer compositions, wherein a raw asphalt with a certain constitution is first screened as the raw material of the modified asphalt, and then reacted with the three block polymer SBS as a polymer modifier and a vinyl aromatic (such as styrene) as an assistant added thereto in an inert environment to yield a sample with good stable performance. There is a limit to the source of the raw material of the modified asphalt in this process, and styrene as an assistant is of no help in the dispersion of SBS in asphalt. In addition, the reaction cost increases since a nitrogen environment is needed.
U.S. Pat. Nos. 5,336,705, 5,627,225, and 5,348,994 first use fuming sulfuric acid or other sulfonating reagent to sulfonate the raw asphalt and the polymer modifier to incorporate acidic groups into both of them, and then neutralize with alkalis such as CaO, ZnO, etc. as neutralization reagents. This process prolongs the preparation process, increases the production cost, and results in corrosion of the apparatus by sulfonating reagents.
U.S. Pat. No. 5,306,750 discloses a process for reacting a polymer with asphalt, and a polymer-linked-asphalt product. This process is to covalently react 0.05-2 wt % of an epoxide-containing polymer with asphalt at a temperature above 100° C. for longer than 1 h. No phase separation happened with the modified asphalt obtained by this process after storing in a drying oven at 163° C.-177° C. for 4 days.
U.S. Pat. No. 5,331,028 discloses a polymer-modified asphalt composition and its preparation process. The constitution of the composition is that the reaction product derived by the reaction between 100 parts by weight of asphalt and 0.5-11 parts by weight of an ethylene copolymer containing glycidyl accounts for 80-99.7 wt %, and that the styrene/conjugated diene block copolymer accounts for 0.3-20 wt %. The process is to mix 70-99.2 wt % of asphalt, 0.5-10 wt % of the ethylene copolymer containing glycidyl, and 0.3-20 wt % of a styrene/conjugated diene block copolymer, and to react at 170° C.-220° C. for 6-36 h to yield a reaction product.
Although the compatibility of the polymer with asphalt used in U.S. Pat. Nos. 5,331,028 and 5,306,750 is rather good, the high preparation cost of the polymer and the difficulty in reaction are the major control factors.
One of the objectives of the present invention is to provide a storage-stable modified asphalt composition.
Another objective of the present invention is to provide a process for preparing the storage-stable modified asphalt composition.
SUMMARY OF THE INVENTION
The present invention provides a storage-stable modified asphalt composition, which comprises:
base asphalt
50-97.7 parts by weight;
polymer having double bonds
2.0-20.0 parts by weight;
compatibilizer
0.1-20.0 parts by weight;
cross-linking reagent
0.1-10.0 parts by weight;
organic polar compound
0.1-10.0 parts by weight;
and the softening point difference of its product determined by the stability test is lower than 2.5° C.
The present invention also provides a process for preparing the storage-stable modified asphalt composition, which comprises mixing 50-97.7 parts by weight of a base asphalt, a 2.0-20.0 parts by weight of a polymer having double bonds, 0.1-20.0 parts by weight of a compatibilizer, 0.1-10.0 parts by weight of a cross-linking reagent, and 0.1-10.0 parts by weight of a organic polar compound under certain conditions.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a storage-stable modified asphalt composition, which comprises:
base asphalt
50-97.7 parts by weight;
polymer having double bonds
2.0-20.0 parts by weight;
compatibilizer
0.1-20.0 parts by weight;
cross-linking reagent
0.1-10.0 parts by weight;
organic polar compound
0.1-10.0 parts by weight;
and the softening point difference of its product determined by the stability test is lower than 2.5° C.
Said base asphalt is one selected from the group consisting of petroleum asphalts, coal-tar asphalts, tar sand asphalts and native asphalts, or a mixture thereof, wherein the petroleum asphalt is one selected from the group consisting of straight-run asphalts, asphalts obtained by solvent deasphalting, oxidized asphalts, and blended asphalts, or a mixture thereof. Said straight-run asphalt is an atmospheric residue or vacuum residue obtained through atmospheric distillation or vacuum distillation, the Penetration of which at 25° C. is 20-300 dmm (i.e. {fraction (1/10)}mm). Said asphalt obtained by solvent deasphalting is a deoiled asphalt obtained by extracting a residue with one of the C
3
-C
5
hydrocarbons or their mixtures. The Penetration of the deoiled asphalt at 25° C. is 5-200 dmm.
Said polymer having double bonds is a block polymer of styrene-butadiene in a ratio of 20-45:80-55 which mainly refers to the SBS type. The structure of SBS is star or linear, the molecular weight of which is in the range of 100,000 to 350,000. The block polymer can be either a dry rubber, or an oil-extended polymer wherein 2-60 wt % weight of oil is extended.
Said compatibilizer is one selected from the group consisting of styrene tar, tall oil, acid-containing tall oil, catalytically cracked oil slurry, heavy deasphalted oil, extracted oil obtained by solvent refining, naphthenic acid, naphthenic oil, white oil, and coal tar fractions, or a mixture thereof.
Said cross-linking reagent is one selected from the group consisting of crystallized sulfurs, activated sulfurs, sulfur-donors, and “symbolizing” sulfur-donating cross-linking reagents, or a mixture thereof. Said activat
Guo Shuhua
Huang Weiqi
Long Jun
She Yucheng
Wang Zijun
China Petroleum & Chemical Corporation
Szekely Peter
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