MXPA00001117A - Emulsified bituminous binder - Google Patents

Abstract

A bitumen emulsion comprising bituminous binder, emulsifier, and water. The bituminous binder comprises bitumen and an oxidised wax, and optionally one or more polymers. The incorporation of the oxidised wax into the bituminous binder provides modified bitumen with both a high softening point and a low enough viscosity to allow it to be emulsified. The emulsion may be used as a tack coat in applying a waterproofing layer to a roof base. The emulsion may be made using a static mixing emulsion process.

Description

"EMULSIFIED BITUMINOUS AGLUTINANT" The present invention relates to an asphalt emulsion composition useful, for example, in the bonding of bituminous layers impermeable to substrates such as roof bases. Conventionally, before applying a bituminous layer impervious to a substrate such as a roofing base comprising, for example, iron, steel, or concrete, the substrate must first be coated with a sticky substance, or sticky layer, which acts to bind the waterproof bituminous layer with the substrate. The waterproof layer is then applied, and the sticky layer and the impervious layer are heated together to achieve bonding in the substrate. The sticky layer typically comprises a polymer modified asphalt composition containing a considerable proportion, eg, 40 to 60 weight percent light flux (s), the flux being required to reduce the viscosity of the asphalt to allow Apply to the substrate. After applying the sticky layer to the substrate, a delay is incurred before the impermeable layer can be applied since the flux must first be allowed to evaporate. Even so, there is a possibility that a certain amount of this highly flammable flux may still be present - - causing potential health and safety risks to roofing operators when the sticky coating becomes hot. There is still a need for a sticky layer composition which reduces and retards caused by the flux which evaporates and which minimizes the risks when the sticky layer is heated. One solution could be the use of an asphalt emulsion for the sticky layer. An emulsion has the advantage that it is already in an appropriate form for cold application (i.e., at room temperature) to a substrate, and therefore a flux is not required. Therefore, there is little or no delay in applying the impermeable layer after the application of the sticky layer, ie, there is no need to wait for the flux to evaporate, and the danger of using a flammable flux is eliminated. However, due to the high temperatures at which the waterproofing compounds can be subjected during their duration, it is important that the asphalt binder used for the sticky layer has a softening temperature, for example, roofing applications at the point of softening should typically be at least 80 ° C, preferably at least 90 ° C, and more preferably 100 ° C or higher. However, asphalts with a high softening temperature also tend to have high viscosities at elevated temperatures, making them difficult to emulsify. An alternative route is the use of polymers to modify the asphalt, but they also tend to increase the viscosity of asphalt making it difficult to emulsify. Accordingly, there is a need for a bituminous binder having a viscosity low enough to be emulsified, but a softening temperature high enough to withstand the temperatures that occur during uses such as sticky layers in the binding of a bituminous layer impermeable to a substrate. The present invention provides an oil-in-water emulsion comprising: (a) from 30 percent to 70 percent by weight of a bituminous binder having a penetration of 40 to 150 millimeters / 10 (Method D5 of the American Society) for Material Testing), a softening temperature of 60 ° C to 120 ° C (Method D36 of the American Society for the Testing of Materials) and a kinematic viscosity at 160 ° C of less than 250 square millimeters per second, of preference of 150 to 250 square millimeters per second (Method D2170 of the American Society for the Testing of Materials), the binder comprising from 88 percent to 99.5 percent by weight of asphalt having a penetration of 70 to 300 millimeters / 10 and a softening temperature of 30 ° C to 50 ° C, and 0.5 to 12 weight percent of an oxidized wax; (b) from 0.01 percent to 5 percent by weight of an emulsifier; and (c) from 25 percent to 69.9 percent by weight of water. The oxidized wax is preferably derived from a high density polyethylene wax, for example, by oxidation with air of a high density polyethylene wax. Preferably, the oxidized wax has a melting temperature of 100 ° C to 150 ° C (Method D3418 of the American Society for the Testing of Materials) most preferably from 120 ° C to 140 ° C, a dynamic viscosity at 150 ° C from 200 to 10,000 Pa.s which is measured using a Brookfield viscometer, and an acid number of 10 to 50 milligrams of KOH / gram (Method D1386 of the Company American for the Test of Materials. Commercially available examples of this oxidized wax are LUWAX OA3 obtainable from BASF, and A-C 316 and A-C 330 which are waxes that can be obtained from Allied Signal. LUWAX, A-C 316 and A-C 330 are factory names.

The bituminous binder used in the emulsion according to the invention has the advantage that it is of a sufficiently low viscosity to allow it to emulsify while having a softening temperature high enough to withstand the high temperatures that possibly occur in the applications such as ceiling placement applications. These properties are achieved by incorporating the oxidized wax into the bituminous binder. A polyethylene wax, more especially an oxidized high density polyethylene wax, is characterized by a high melting temperature and low melt viscosity; the wax thus modifies the properties of the bituminous binder where it is incorporated and allows the binder to have a high softening temperature without a high viscosity corresponding to high temperature. It is further believed that the polar functionality of the wax due to its oxidized state improves the compatibility of the wax with the bituminous binder and also facilitates the emulsifier of the binder. It is preferred to incorporate one or more polymers in the bituminous binder according to the invention, to improve the mechanical performance of the bituminous binder through a wide temperature scale, for example, tensile strength, cohesion, flexibility at low temperature. Preferably, the total amount of the polymer material contained in the binder, in addition to the oxidized wax, is 0.5 percent to 10 percent by weight based on the total weight of the binder. The polymers can be elastomers or plastomers and are selected from styrene-alkadiene copolymers, alpha-olefin copolymers, alkylene-vinyl acetate copolymers, alkylene-acrylate copolymers and alkylene-alkyl acrylate copolymers, or a mixture of two or more thereof. Beneficially, the emulsion contains from 0.1 percent to 6 percent by weight, preferably from 1 percent to 4 percent by weight of an elastomer that is selected from styrene-alkadiene-styrene copolymer polymers, and 0.1 percent to 10 weight percent, preferably 1 to 6 weight percent of a plastomer that is selected from alkyl vinyl acetate copolymers, alkylene acrylate copolymers and alkylene alkyl acrylate copolymers, wherein the alkylene monomer contains from 1 to 5 carbon atoms, the percentages by weight being based on the total weight of the bituminous binder. Examples of suitable styrene-alkadiene copolymers for the elastomer include copolymers of ** "" - *** styrene-butadiene block ("SBS") and styrene-isoprene block copolymer, with SBS being a preferred copolymer. The molar ratio of styrene butadiene typically falls within the range of 20:80 to 45:55, and the molecular weight of SBS typically falls within the range of 50,000 to 150,000. Examples of suitable copolymers for the plastomer include ethylene-vinyl acetate copolymer ("EVA"), ethylene-methacrylate copolymer ("EMA") and ethylene-ethylmethacrylate ("EMMA"), with EVA being a preferred copolymer. Preferably, the vinyl acetate content of the EVA is 10 percent to 30 mole percent, and the EVA preferably has a melt index of 100 to 4,000. The molecular weight of the plastomer is preferably from 5,000 to 50,000, more preferably from 10,000 to 30,000. The asphalt used in the emulsion can be obtained from a variety of sources including a vacuum residue of first distillation; vacuum residue mixtures with diluents such as vacuum tower wash oil, paraffin distillate, aromatic and naphthenic oils and mixtures thereof; oxidized vacuum residues or oxidized mixtures of vacuum residues and diluting oils and the like. Typically, the asphalt will have an atmospheric boiling temperature of at least 380 ° C, a penetration (mm / 10) of 70 to 300, preferably 150 to 250, at 25 ° C (Normal Test D5 of the American Society for the Materials Test), a softening temperature (Ring and Ball) of 30 ° C to 50 ° C, preferably 35 ° C to 50 ° C (Method D36 of the American Society for the Testing of Materials), and a kinematic viscosity of 100 to 500 square millimeters per second at 135 ° C (Method D2170 of the American Society for the Testing of Materials). A mixture of two or more different asphalts can be used. The amount of the emulsifier employed may vary from 0.1 to 5 weight percent, but usually an amount of 0.1 weight percent to 2 weight percent more preferably from 0.1 weight percent to 1 weight percent is used, depending on the type of emulsifier, as would be readily determined by a person skilled in the art. The emulsifier can be cationic, anionic or non-ionic, or a mixture of cationic and non-ionic or anionic and nonionic emulsifiers, depending on the desired electrochemical properties of the emulsion and the proposed use of the emulsion, for example the type of surface in where the emulsion is going to be applied as a sticky layer. Suitable cationic emulsifiers include fatty amines, fatty amido-amines, ethoxylated amines, imidoazalins, quaternary ammonium salts, and mixtures thereof. Preferably, the cationic emulsifier is a diamine, for example tallow propylene diamine, and more preferably is a mixture of a diamine with a quaternary ammonium salt. When a cationic emulsifier is employed, it is preferred to include an acid in the emulsion of the asphalt to counteract the alkalinity of the emulsifier. An acid is usually added to adjust the pH of the emulsion to about pH 2 to 7. Typically, 0.01 percent to 1 weight percent acid is added based on the total weight of the emulsion. Suitable acids include inorganic acids, for example, hydrochloric acid. Suitable anionic emulsifiers include long chain carboxylic and sulfonic acids, their salts and mixtures thereof. Suitable nonionic emulsifiers include ethoxylated compounds, for example ethoxylates of sorbitan esters, alcohols and alkylphenols, and mixtures thereof. The emulsion according to the invention may contain other additives well known to those skilled in the art of asphalt emulsions to adjust the properties of the emulsion in relation to the intended use, the method of application, and storage conditions. These include, for example, mineral salts, thickening agents, antifreeze agents and the like. The bitumen binder can be prepared by first mixing the optional polymers in the asphalt with a high efficiency agitator, at a temperature typically within the range of 160 ° C to 200 ° C, for a sufficiently long time to ensure dispersion and swelling of the polymers, as is well known to those skilled in the art of polymer asphalt modification, then adding the oxidized wax and continuing with the mixing, generally for no more than 1 hour. The emulsion can be prepared by any suitable emulsification process but is preferably prepared by a static mixing process as disclosed in published European Patent Application Number 283246A, the disclosure of which is incorporated herein by reference. The process of preference comprises the following steps: a) feeding the bituminous binder towards a first static mixer at a temperature greater than 100 ° C; b) introducing water under pressure in the first static mixer, the pressure being sufficient to prevent considerable evaporation of the water, the weight ratio of the asphalt to the water in the first static mixer being between 2: 1 and 15: 1, preferably between 2: 1 and 10: 1; c) introducing the emulsifier into the first static mixer; d) mixing the components in the first static mixer I i, and then passing the mixture, resulting from the first static mixer towards i 'at least another mixer in which the temperature is lower than the boiling temperature of the water; i) introducing the water into the other mixer (s) J in an amount such that the total amount ji of water present in the resulting emulsion is from 25 percent to 69.9 percent by weight, based on the weight total of the emulsion; and f) passing the mixture through the other mixer (s) and removing the resulting asphalt emulsion. Preferably, the other mixer is also a static mixer. To facilitate the introduction of the emulsifier in the first static mixer, the emulsifier, in paite The asphalt is preferably introduced into the first static mixer at a temperature of 100 ° C to 1 ° C. 200 ° C, more preferably from 30 ° C to 200 ° C, and at a pressure of 2 to 80 bars, more preferably 10 to 50 bars. The water or soap is preferably introduced into the same mixer at a temperature of 20 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. and also at pressure from 2 to 80 bars, more preferably from 10 to 50 bars. The temperature in the first mixer is usually 70 ° C to 200 ° C, 'more preferably, 100 ° C to 160 ° C. A high temperature I facilitates the emulsification of the asphalt and water, and! Relatively high pressure prevents the water from boiling. It is preferred to pass the resulting mixture I from the first static mixer directly to the other mixer, which is also preferably a static mixer I. The remainder of the water is introduced into this other mixer, preferably cold, for example at a temperature of 5 ° C to 20 ° C, so that it cools the emulsion allowing the resulting emulsion to leave the other mixer at its temperature. lower than the boiling temperature the ^ £% * ^ Water. It is also advantageous to operate this other mixer at a reduced pressure relative to the first mixer, so that the emulsion leaves the other mix at atmospheric pressure. Any of the other additives to be included in the emulsion can be added at any stage during the process, still preferably added to the first static mixer to ensure complete mixing, and conveniently added at the same time as the emulsifier. The process of preference is a process of mixers, but more than two mixers can be used. These additional mixers can be static mixers or other types of mixers, such as a colloid mill. Examples of suitable static mixers are those known as Sulzer or Kenics mixers, which are well known to those skilled in the field of static mixing. The static mixing process described above has the advantage that it produces an emulsion in which the droplets of the asphalt are of a small particle size and relatively critical size distribution. Typically the droplets of the asphalt have a median particle size of 1 to 8 micrometers (μm), preferably 2 to 7 micrometers, with a normal deviation of no more < ugly- «k-S j« fó «efc¡fc-. of 0.3 (which is measured using a Coulter® Multisizer particle size analyzer). This has the advantage that the resulting emulsion is stable during storage, but, once it is applied to the substratum, it disintegrates relatively more quickly and uniformly. ! ! The asphalt emulsion according to the invention is beneficially used as a sticky layer to bind a waterproof bituminous layer to a roofing base, even though it may find use in any of the other similar applications where it is used. you need - a binder to bind two substrates or materials together. The asphalt emulsion can be applied to the substrate using any suitable technique, for example, by spraying. The invention will now be illustrated by means of the following Example: EXAMPLE A series of polymer-modified bitumen binders was prepared using one or more of the components as detailed in Table 1 to I, penetration grade asphalt, temperature of. softening and viscosity as shown in Table 1. A linear styrene-butadiene block copolymer ("SBS") having a molar ratio of styrene: butadiene of 31:69, and a weight average molecular weight of 100,000; j an ethylene-vinyl acetate copolymer < ("EVA 1") of a melt index of 3000 grams I for 10 minutes (Method D1238 of the Society '1 American for Material Testing), a content of 14 percent by weight of acetate! of vinyl, and an average molecular weight in j I weight of 14, 000; a low molecular weight ethylene-vinyl acetate copolymer ("EVA 2") of a viscosity, Brookfield of 450 mPa.s at 150 ° C, and a content of vinyl acetate, of 13 weight percent, and a molecular weight in weight of 5,500; and an oxidized high density polyethylene wax with a melting temperature of 128 ° C (Method D3414J of the American Society for the Test of Materials), Brookfield viscosity of 3800 m Pa ,. s at 150 ° C, and an acid number of 22 milligrams < of KOH / gram (Method D1386 of the American Society for the Testing of Materials), j produced by an air oxidation of high density polyethylene wax of molecular weight j of 9,000. 1 The components were mixed with a turbine agitator operating at 175 ° C for 2 to 4 hours in order to obtain a homogeneous mixture. The modified bitumen binders resulting polymers were then emulsified according to the static mixing process described above to produce cationic emulsions from 60 percent to 70 percent by weight binder content. In order to produce the emulsion, a water-mixed soap was first prepared, and a commercially available emulsifier, a saponified tallow propylene diamine with acid, was prepared. which was added an additional amount of water, as indicated in Table 2. fc £ -t ^ BtS * T: Where a satisfactory emulsion was obtained, that is, where the emulsification process was not available! failed because the viscosity of the bituminous binder was too high, the emulsion was tested for particle size distribution and storage stability. The size distribution of the particle was determined by means of a Coulte'r® Multisizer: the particle size mediating d5Q means that 50 percent of the mass of the binder is particles of diameter lower than d5Q; The size variation is obtained by the formula "0.5 log (dg ^ / d ^ g)" with d84¡ and d 5 having the same meaning as d5Q. The storage stability is expressed by the sedimentation percentage at the bottom of a 100 millimeter high flask containing the emulsion and stored for 7 days at 25 ° C, with the exception for Reference Example H where the storage it was maintained for 50 days under the same conditions. Referring to Table 1 it can be seen that the binder A consisting only of hard grade asphalt is of a viscosity low enough to be emulsified but does not have a sufficiently high softening temperature (> 60 ° C in general) to resist the high temperatures that occur in applications such as the sticky layer when agglutinating bituminous layer impermeable to a substrate, for example a roofing base. On the contrary, the binder B has a sufficiently high softening point at 85 ° C for these high temperature applications but is too viscous to emulsify satisfactorily. The binders C to H all comprise a polymer modified asphalt, the asphalt being of a penetration class of 180/220. The binders E and F each contain asphalt and polymer but no oxidized wax. Each one has acceptably high softening temperatures but they are too viscous to emulsify. The binders C, G and H have added oxidized wax, providing the binders with acceptably high softening temperatures comparable to the binders E and F, but with significantly reduced viscosities allowing these binders to emulsify.

Table 1 Composition and Characteristics of Modified Bituminous Binders Reference to A D Binder Composition of Binder Asphalt Quality Pen 10 1 mm 35/50 180/220 180/220 Quality of Asphalt Blown 85/25 Asphalt% of mass 100 100 92 EVA 1 SBS EVA 2 Oxidized HDPE Wax p Binder Properties Brazing Temperature 53 85 81 78 Penetration at 25 ° C 10"41 25 72 59 Viscosity at 160 ° C mm2 / s 183 1150 216 196 Emulsifiability OK Fail OK OK Table 1 (continued) Reference to the Binder Binder Composition Asphalt Quality Pen 10_1 mm 180/220 180/220 180/220 180/220 Asphalt Quality Blown Asphalt% mass 86 95 90 90 EVA 1 p 6 - 5 4 SBS 2 5 2 2 EVA 2 6 - Wax of Oxidized HDPE Binder Properties Brazing Temperature 83 95 89 104 Penetration at 25 ° C 10"79 66 63 Viscosity at 160 ° C mm? S 315 450 215 190 Emulsifiability * Failure Fault OK OK The emulsifiability is defined in this case to mean that the resulting mixture was an emulsion that was stable during storage at 25 ° C for at least 7 days.

Table 2 Manufacturing and Properties of Emulsions Reference to Emulsion Reference to Binder A Composition of the Emulsion Amount of the binder% of 65.5 58.5 59.9 59.9 60.00 mass Water in the first mixer 10.5 13.0 12.4 12.4 12.45 Emulsifier 0.6 0.5 0.5 0.5 0.50 Acid (special quality 1.6) 0.4 0.4 0.4 0.4 0.38 Water in the second mixer 23.0 27.6 26.8 26.8 26.70 - "- > 'f7 * (Picture '2 continuation) Operating Parameters Binder Temperature 164 159 159 163 165 Pressure in the first mixer 10 ° Pa 32 27 32 31 42 Temperature in the first mixer 138 127 132 132 139 Pressure in the second mixer 10D Pa 13 Temperature in the second mixer 90 83 86 Properties of Emulsion Content of% Binder mass 66.5 58.5 58.2 59.8 60.0 PH 3.1 2.2 2.4 2.4 2.6 Medium particle size d50 (*) μm 4.71 5.32 6.55 6.64 3.48 Size Variation 0.25 0.2Í 0.26 0.27 0.32 Sedimentation after 7 days 0 0.04 (50 days) (*) Coulter® Multisizer, 70 micrometer cell

Claims (10)

CLAIMS:

1. An oil-in-water emulsion comprising by weight based on the weight of the emulsion: (a) from 30 percent to 70 percent by weight of the bituminous binder having a penetration of 40 to 150 millimeters / 10 (Method D5 from the American Society for the Testing of Materials), a softening temperature of 60 ° C to 120 ° C (Method D36 of the American Society for the Testing of Materials and a kinematic viscosity at 160 ° C of less than 250 square millimeters per second, (Method D2170 of the American Society for the Testing of Materials), the binder comprising 88 percent to 99.5 percent by weight of asphalt having a penetration of 70 to 300 millimeters / 10 and a softening temperature of 30 ° C at 50 ° C, and from 0.5 percent to 12 percent by weight of an oxidized wax, (b) from 0.01 percent to 5 percent by weight of the emulsifier, and (c) from 25 percent to 69.9 percent by weight of water 2.

An emulsion in accordance with the claim ation 1 wherein the oxidized wax is an oxidized high density polyethylene wax having a melting temperature within the range of 100 ° C to 150 ° C, a Brookfieid dynamic viscosity at 150 ° C of 200 to 10,000 mPa.s , and an acid number of 10 to 50 milligrams of KOH / gram.

An emulsion according to claim 1 or 2, wherein the bituminous binder also comprises from 0.1 percent to 6 weight percent of a styrene-alkad copolymer.

4. An emulsion according to claim 3, wherein the styrene-alkad copolymer is a styrene-butad copolymer ("SBS").

An emulsion according to any of the preceding claims wherein the bituminous binder also comprises from 0.1 percent to 10 percent by weight of a copolymer selected from alkylene-vinyl acetate copolymers, alkylene-acrylate copolymers and alkylene-alkyl acrylate copolymers.

6. An emulsion according to claim 5, wherein the copolymer is ethylene-vinyl acetate.

A method for preparing an emulsion according to any of the preceding claims comprising: a) feeding the bitumen binder towards a first static mixer at a temperature greater than 100 ° C; b) introducing water under pressure in the first static mixer, the pressure being suffic to prevent considerable evaporation of the water, the weight ratio of the asphalt to the water in the first static mixer being between 2: 1 and 15: 1; c) introducing the emulsifier into the first static mixer; d) mixing the components in the first static mixer, and then passing the resulting mixture from the first static mixer to at least one other mixer where the temperature is lower than the boiling temperature of the water; e) introducing water in the other mixer (s) in an amount such that the total amount of water present in the resulting emulsion is from 25 percent to 69.9 percent by weight, based on the total weight of the emulsion; and f) passing the mixture through the other mixer (s) and removing the resulting asphalt emulsion.

8. A composition of the bituminous binder having a penetration of 40 to 150 millimeters / 10 (Method D5 of the American Society for the Testing of Materials), a softening temperature of 60 ° C to 120 ° C (Method D36 of the American Society for Material Test) and a kinematic viscosity at 160 ° C of less than 250 square millimeters per second, (Method D2170 of the American Society for Testing Materials), the binder composition comprises from 88 percent to 99.5 percent by weight of asphalt having a penetration of 70 to 300 millimeters / 10 and a softening temperature of 30 ° C to 50 ° C, and 0.5 to 12 weight percent of an oxidized wax.

9. A composition of the bituminous binder according to claim 8, wherein the oxidized wax has a melting temperature of 100 ° C to 150 ° C (Method D3418 of the American Society for the Testing of Materials), a Brookfield dynamic viscosity at 150 ° C of 200 to 10,000 mPa.s, and an acid number of 10 to 50 milligrams KOH / gram (Method D1386 of the American Society for the Testing of Materials).

10. A bituminous binder composition according to claim 8 or 9, wherein the oxidized wax is an oxidized high density polyethylene wax.