KR100473664B1 - Process for preparing bitumen compositions - Google Patents

Abstract

The present invention relates to a method for preparing a bitumen composition comprising mixing an oxidation bitumen having a penetration index of 0 or more with a thermoplastic rubber present at less than 5% by weight based on the total bitumen composition at an elevated temperature; Bitumen compositions obtainable in this way; And the use of such bitumen compositions in asphalt mixtures for road construction.

Description

Production method of bitumen composition {PROCESS FOR PREPARING BITUMEN COMPOSITIONS}

The present invention relates to a process for preparing bitumen compositions, to bitumen compositions obtainable by these methods and to their use in asphalt mixtures for road construction.

Bitumen is used as a binder in road asphalt mixtures and has been continually evolving to meet increasing performance demands from road builders. In general, bitumen performs well on road asphalt, but due to the increasing traffic volume, many roads are prematurely worn due to surface cracks and blemishes. Cracks are a serious defect in road asphalt, causing water to reach the lower layers of the road surface, leading to the need for early repair. Increasing the bitumen content of the asphalt or using more flexible grade bitumen increases the crack resistance of the asphalt at low temperatures but increases the risk of excessive lubrication at high temperatures because the mixture is actually more flexible. Conversely, the rubbing resistance can be improved by reducing the bitumen amount in the asphalt mixture or by using a firm grade bitumen, but the crack resistance is reduced because the mixture is less flexible.

In view of the above, it is clear that it is advantageous to develop a hard bitumen composition that satisfies current cracking requirements, ie a bitumen composition having both good low temperature performance and good high temperature rubbing resistance.

It is known that the low temperature properties of bitumen can be improved by mixing polymers and bitumen. However, when this modification is applied to hard bitumen, incompatibility between bitumen and polymers is generally observed, with little or no improvement in low temperature properties and relatively poor aging. Results in a reaction.

It is also known to conventionally blow the bitumen / polymer mixtures to produce industrial and roofing-grade bitumen. However, these bitumen compositions appear to be inadequate for road construction because of their high softening point and relatively high penetration.

It is an object of the present invention to provide a bitumen composition suitable for road construction which has both good low temperature performance and good high temperature rubbing resistance and further shows an improved aging reaction.

Surprisingly, it has been found that such bitumen compositions can be prepared by mixing certain bitumen with thermoplastic rubber.

Therefore, the present invention relates to a method for producing a bitumen composition comprising mixing an oxidation bitumen having a penetration index of 0 or more with a thermoplastic rubber present at less than 5% by weight based on the total bitumen composition at an elevated temperature.

Preferably, the bitumen has a penetration index of 5 or less. More preferably, bitumen has a penetration index in the range of 0-2.

Suitably, the thermoplastic rubber is present in the range of less than 3% by weight, preferably 0.1 to 2.5% by weight, based on the total bitumen composition.

Suitably, the process is carried out in the temperature range of 160 to 220 ° C.

Preferably, the process according to the invention is carried out in the temperature range of 170 to 190 ° C.

The method can be carried out at ambient or elevated pressure. Usually, however, it is carried out at ambient pressure.

Suitably, the method is carried out for a time of less than 6 hours, preferably less than 2 hours.

Oxidized bitumen is suitably obtained by blowing the bitumen. More preferably, the bitumen oxide is obtained by catalytic blowing the bitumen. Suitable catalysts used in such blowing processing include those familiar in the art such as ferric chloride, phosphorus pentoxide, aluminum chloride, boric acid and phosphoric acid, with phosphoric acid being preferred. The catalyst is usually added to the bitumen to be blown at less than 2.5% by weight based on bitumen. Blowing is carried out with an oxygen containing gas such as air or pure oxygen. Preferably, air is used. Blowing can be performed at ambient or elevated pressures. Usually, however, it is carried out at ambient pressure.

Suitably, the catalytic blowing process is carried out for a time of less than 8 hours, preferably less than 4 hours.

Suitably, this blowing process is carried out in the temperature range from 200 to 350 ° C., preferably from 250 to 300 ° C.

The bitumen to be oxidized can be bitumen derived from propane bitumen, butane bitumen, pentane bitumen or mixtures thereof, distillation residues of crude oil, cracked residues, crude oil extracts. Other suitable bitumens include mixtures of the bitumen with extenders (flushs) such as petroleum extracts, such as aromatic extracts, distillates or residues. Suitably, the bitumen to be oxidized has a chip size (measured by ASTM D 5 at 25 ° C.) in the range of 50 to 400 dmm, preferably 100 to 300 dmm, more preferably 200 to 300 dmm, and 30 to 65 ° C. , Preferably with a softening point (measured by ASTM D 36) in the range from 35 to 60 ° C.

The invasion index (PI) of the oxidized bitumen is determined using the invasiveness and softening point as is well known to those skilled in the art (see, for example, the Shell Bitumen Handbook, 1991, pages 74 and 75).

Bitumen oxide is mixed with thermoplastic rubber. Suitably, the bitumen oxide may be mixed with one or more different types of thermoplastic rubber.

A wide range of thermoplastic rubbers may be suitably used in accordance with the present invention, but preferred thermoplastic rubbers include at least two terminal poly (monovinylaromatic hydrocarbon) blocks and at least one central poly (conjugated diene) block, optionally hydrogenating to form a continuous network. Block copolymers.

Preferably the block copolymer component is selected from the group consisting of the formula A (BA) m or (AB) nX, wherein A is a predominantly block copolymer of poly (monovinylaromatic hydrocarbon), B is mainly poly ( Conjugated diene) block, X represents a residue of a polyvalent coupling agent, n represents an integer of 1 or more, preferably 2 or more, and m represents an integer of 1 or more, preferably 1.

More preferably, block A mainly represents a poly (styrene) block and B block mainly represents a poly (butadiene) block or a predominantly poly (isoprene) block. Multivalent coupling agents used include conventional ones known in the art.

The term “predominantly” means that blocks A and B are each monovinyl aromatic hydrocarbon monomers and conjugated diene monomers, which monomers may be mixed with other structurally related or unassociated comonomers, such as monovinyl aromatic as main component. Mostly derived from hydrocarbon monomers and small amounts (up to 10%) of other monomers or butadiene mixed with isoprene or small amounts of styrene.

More preferably, the block copolymer comprises pure poly (styrene), pure poly (isoprene) or pure poly (butadiene) blocks, wherein the poly (isoprene) or poly (butadiene) blocks are selectively hydrogenated to Residual ethylenic unsaturations of up to 20%, more preferably less than 5%, of the original unsaturated content. However, preferably the block copolymer is not selectively hydrogenated. Most preferably, the applied block copolymer has the structure ABA, where A has a molecular weight of 3000 to 100,000, preferably 5000 to 25,000, and diblock AB has a molecular weight in the range of 50,000 to 170,000. Has Preferably, it has an apparent molecular weight in the range of 70,000 to 120,000.

As used herein, the term "skin molecular weight" refers to the molecular weight of a polymer measured by gel permeation chromatography (GPC) using poly (styrene) assay criteria.

The initially prepared poly (conjugated diene) blocks usually contain 5 to 65% by weight of vinyl groups derived from 1,2-polymerization with respect to conjugated diene molecules, and preferably 10 to 55% by weight of vinyl.

The complete block copolymers used according to the invention usually comprise from 10 to 60% by weight and preferably from 15 to 45% by weight of polymerized vinyl aromatic hydrocarbon monomers.

The apparent molecular weight of the entire block copolymer is usually in the range of 100,000 to 500,000 and preferably in the range of 250,000 to 450,000, and most preferably in the range of 350,000 to 400,000.

Examples of suitable pure block copolymers include KRATON G-1651, KRATON G-1654, KRATON G-1657, KRATON G-1650, KRATON G-1701, KRATON D-1101, KRATON D-1102, KRATON D-1107, KRATON D -1111, KRATON D-1116, KRATON D-1117, KRATON D-1118, KRATON D-1122, KRATON D-1135X, KRATON D-1184, KRATON D-1144X, KRATON D-1300X, KRATON D-4141 and KRATON D -4158 (KRATON is a registered trademark).

The present invention also provides bitumen compositions obtainable by one of the methods described above. Such bitumen compositions are very attractive because they exhibit good low temperature performance and good high temperature scratch resistance.

Suitably, the bitumen composition has a penetration of 30 to 300 dmm, preferably 100 to 200 dmm (measured by ASTM D 5 at 25 ° C.), and a range of 50 to 120 ° C., preferably 60 to 100 ° C. Has a softening point of (measured by ASTM D 36).

Suitably, this bitumen composition has a G * / sinδ-value in the range of at least 1 kPa (at 64 ° C.), preferably in the range of 1 to 2 kPa (at 64 ° C.), and at least 0.30 (at −6 ° C.), preferably Preferably have an m-value of 0.33 (at -6 ° C.) or higher (G * / sinδ-values and m-values are defined in Superpave Series No. 1 (SP-1), Asphalt Institute for reference).

Fillers such as carbon black, silica and calcium carbonate, stabilizers, antioxidants, pigments, and solvents are known to be useful in bitumen compositions and can be incorporated into bitumen compositions of the present invention at concentrations familiar to the art.

The present invention also provides the use of the bitumen composition of the above in an asphalt mixture for road construction.

The invention is illustrated by the following examples.

Example  One

The bitumen of PI -0.7 was subjected to catalytic blow processing using phosphoric acid as a catalyst, and then the blown bitumen obtained was mixed with a naphthenic flux to obtain an oxidation bitumen of PI 0.8. The oxidized bitumen is then mixed with 2% by weight of non-hydrogenated radial polystyrene-polybutadiene-polystyrene block copolymer based on the total bitumen composition at 180 ° C. for 1 hour. The block copolymer contains a polystyrene-polybutadiene diblock having a styrene content of 30% by weight, an apparent molecular weight of 380,000 and an apparent molecular weight of 112,000. The main properties of the bitumen composition thus obtained are given at the top of Table 1.

The bitumen composition obtained is then aged in a pressure aging vessel (AASHTO PP1) via a Rolling Thin film Oven Test (ASTM Test Method D 2572). The main properties of the bitumen composition after these aging tests are given in the lower part of Table 1.

Example  2

The non-oxidized bitumen of PI -0.9 is carried out in a similar manner as described in Example 1 except for mixing with 4 weight percent of the radial polystyrene-polybutadiene-polystyrene block copolymer based on the total bitumen composition. The main properties of the non-oxidized bitumen composition thus obtained are given at the top of Table 1.

The bitumen composition is then aged in a pressure aging vessel (AASHTO PP1) via a rotary thin film oven test (ASTM test method D 2572). The main properties of the bitumen composition after these aging tests are given in the lower part of Table 1.

Bitumen Composition Example 1 Example 2 Penetration at 25 ° C., before RTFOT / PAV , dmm 151 113 Softening Point (R & B), Viscosity at 49.5 62.9135 ° C., Pa.s 0.764 0.81864 ° C. G * / sinδ, kPa 1.13 1.23 RTFOT after 64 ℃ G * / sinδ, kPa 3.87 2.47 RTFOT / PAV in after 19 ℃ G sinδ, kPa 2082 m- value 0.333 0.317 hARDNESS, MPa 124 278-24 ℃ in 4094-24 ℃

The bitumen composition prepared according to the invention from Example 1 (Example 1) is characterized in that i) improved high temperature rubbing resistance (after RTFOT) and ii) improved as compared to the bitumen composition outside of the scope of the invention (Example 2) It is clear to show low temperature performance (after RTFOT / PAV). This is a particularly surprising finding given the fact that much less block copolymer is applied in Example 1.

Claims (13)

A method for producing a bitumen composition comprising mixing a bitumen oxide having a penetration index of 0 or more with a thermoplastic rubber present at less than 5% by weight based on the total bitumen composition. The method according to claim 1, wherein the bitumen has a penetration index of 5 or less. The method of claim 2 wherein the bitumen has a penetration index in the range of 0-2. The process according to any one of claims 1 to 3, wherein the thermoplastic rubber is present in less than 3% by weight. 5. A process according to claim 4 wherein the thermoplastic rubber is present at 0.1 to 2.5 wt%. 4. A process according to any one of claims 1 to 3 wherein the bitumen comprises a catalytically blown bitumen. 4. The preparation according to any one of claims 1 to 3, wherein the thermoplastic rubber comprises an optionally hydrogenated block copolymer consisting of at least two terminal poly (monovinylaromatic hydrocarbon) blocks and at least one central poly (conjugated diene) block. Way. The block copolymer according to claim 7, wherein the block copolymer has the structure A (BA) m or (AB) nX, wherein A mainly represents a poly (monovinylaromatic hydrocarbon) block and B mainly represents a poly (conjugated diene) block, X represents a residue of a polyvalent coupling agent, n is an integer of 1 or more and m is an integer of 1 or more. 9. A method according to claim 8, wherein the A blocks are mainly poly (styrene) blocks and the B blocks are mainly poly (butadiene) blocks or mainly poly (isoprene) blocks. 9. A process according to claim 8 wherein the diblocks prepared from A and B have an apparent molecular weight in the range of 50,000 to 170,000. The process according to claim 1, wherein the temperature is in the range from 160 to 220 ° C. 5. Bitumen composition obtainable by the method as defined in claim 1. 13. The composition of claim 12 wherein the composition is used in asphalt mixture for road construction.