HK1191038B - Synthetic raw elastomeric compositions in free-flowing pellet form and process for obtaining the same - Google Patents

Description

Raw elastomer composition in free-flowing granular form and process for its preparation

RELATED APPLICATIONS

This application claims priority from united states provisional patent application No. 61/467,733, filed on 25/3/2011, the disclosure of which is incorporated herein by reference.

Technical Field

The present invention relates to the art of producing, storing and using elastomeric compositions, and more particularly, to free-flowing particulate elastomeric compositions and methods of making the same.

Background

Synthetic elastomers are generally useful in a variety of different applications, including those described herein or as modifiers of mechanical and/or rheological properties of other polymers or materials. However, many elastomers, such as Styrene Butadiene Rubber (SBR) in its virgin state, tend to agglomerate, which on the one hand makes them of wide utility, for example as adhesives or impact modifiers, but on the other hand also makes their virgin counterparts more difficult to handle.

For example, the most common commercial raw elastomer is an SBR elastomer with a styrene monomer content of between 3% and 45% w/w, the remainder being butadiene. Due to the high butadiene content, viscosity is one of the most significant properties of these materials, mainly because of their glass transition temperature (transition from solid to viscoelastic phase) below-20 ℃. Moreover, the viscosity of the polymer increases when heated above ambient temperature and even when pressure is applied. When butadiene and styrene are mainly in a random state and the polystyrene block is reduced, the sticking phenomenon is enhanced.

This sticking property makes such free-flowing granular, crumb or particulate SBR elastomers impossible to commercialize (commomerialize) because the stickiness between granules naturally agglomerates with time, a phenomenon also known as "cold flow". On this basis, such SBR elastomers are sold as bulk solids, also weighing more than 25 kg, regardless of the polymerization process.

Thus, raw elastomers in commercial applications are typically in the form of large chunks and further cut, milled or otherwise processed into smaller particles depending on the end use application. This size reduction process must be done on-site or at a time closest to the final treatment process, otherwise the raw elastomer will re-agglomerate and form large solid masses.

To temporarily maintain the small particle state of the raw elastomer, the prior art has employed various antiblocking and partitioning agents ranging from talc or inorganic fillers to complexes in which resins, other polymers and waxes have been used. However, most of these treatments have at least one of the following disadvantages:

a) they require some type of treatment (heating, chemical treatment or other type of treatment) in order to be applied to the elastomer or after application to the elastomer.

b) They impair the properties of the elastomer after final application by compromising viscosity, mechanical or flow properties.

c) The amount required for anti-blocking behavior is very large.

d) The anti-blocking effect is limited by the temperature condition and the time.

Obviously, all the above drawbacks seriously affect the applicability or create an economic burden, making most antiblocking agents unusable or limited for elastomer compositions that have been further formulated, crosslinked or vulcanized, and therefore achieving the desired antiblocking effect with a small amount of treating agent is only temporary. However, such treatments are not generally effective for long periods of time when applied to virgin or raw elastomer compositions, and do not enable them to be commercialized, stored and handled in granular, crumb or pellet form for long periods of time.

One application that is most prone to the above problems is the modification of asphalt in elastomeric compositions.

Asphalt is a viscous, black material used as a binder in pavement construction mixes, and as a waterproofing material. Given that bitumen is a highly impervious adhesive and cohesive material, capable of withstanding high instantaneous stresses and flowing under constant loads, it has the desirable characteristics of constructing a pavement complying with the following functions: i) the pavement structure is waterproof, so that the pavement structure is very sensitive to moisture and effectively prevents rainwater from permeating; ii) provide a tight bond and cohesion between the aggregates capable of withstanding the mechanical action of disintegration resulting from vehicle loading.

However, in the virgin state, asphalt has rheological and thermo-mechanical properties, thereby limiting its application and usefulness in paving. For example, the conventional softening temperature range for virgin asphalt is 50 ℃ to 60 ℃ (rheological failure temperature or RFT). However, the use of polymers increases the temperature, making the RFT above 60 ℃, making the asphalt more resistant to the frictional losses associated with rolling of the vehicle.

Another property of interest is that virgin asphalt has a typical SUPERPAVE (high Performance asphalt pavement) PG type performance rating of PG 64-10. With the help of polymers, the PG range can be extended to 82-22PG grades.

The present invention develops polymer modified asphalt to reduce the energy requirements of road asphalt concrete in production, storage and application. The modified asphalt uses a polymer which can form a three-dimensional network by vulcanization, crystal formation or entanglement of a polymer chain.

The purpose of modifying bitumen by means of polymers is:

a) creating a more viscous binder at high temperatures, thereby reducing the permanent set of the compound constituting the bearing layer (bearing layer) and increasing the stiffness;

b) reducing cracking due to low temperature thermal effects and fatigue, thereby increasing elasticity;

c) an adhesive having optimal adhesive properties.

Bitumen is typically modified using an SBR elastomer composition in the raw state having a molecular mass of about 50,000 to 500,000 daltons. As previously mentioned, elastomers are stored and sold in bulk form and subsequently require the user to perform crushing or grinding on site, thereby increasing the overall process cost of asphalt modification due to energy consumption, labor and time.

To solve the above problems, the prior art has tried various solutions.

One solution is to emulsify the SBR elastomer in water to facilitate its incorporation into the bitumen. However, for polymers with molecular weights (Mw) in excess of 100,000 daltons, the emulsification process is difficult and heavy, and in addition, in addition to asphalt oxidation creating a premature aging factor, thereby shortening the useful life of paving applications, the temperature employed in asphalt modification processes is typically higher than the evaporation temperature of water, causing flashing or sudden water vapor formation of the water, which can lead to accidents.

These emulsified elastomers have several applications in bitumen emulsions and are also well known in the art. These emulsions are mixtures of bitumen and emulsifiers that form a stable emulsion with water, allowing their application on cold bitumen surfaces, i.e. at temperatures below 100 ℃.

One of these techniques is described in us patent 6,136,899, in which a specific type of SBR emulsion can be used to modify an asphalt concrete, thereby greatly improving the resistance of the asphalt concrete prepared therefrom to the effects of preventing the asphalt concrete used from being crushed, ground and cracked at low temperatures. This SBR emulsion is compatible with almost all types of asphalt, and the modified asphalt has a very strong level of force ductility, strength and toughness. According to this patent, the SBR used in its inventive practice to modify the bitumen is a mixture of: (i) a high molecular weight (Mw) styrene-butadiene rubber having an average Mw of at least about 300,000 daltons; (ii) a low Mw styrene-butadiene rubber having an average Mw of less than about 280,000 daltons; wherein the ratio of high Mw styrene-butadiene rubber to low Mw styrene-butadiene rubber is from about 80:20 to about 25:75, and other properties are required for the elastomeric composition to function.

On the other hand, U.S. Pat. No. 6,503,968 discloses an asphalt modification of a styrene-butadiene-styrene block copolymer and a styrene-butadiene latex, wherein the asphalt modification is concerned with an asphalt modification comprising 5 to 30wt% of a dispersed styrene-butadiene-styrene block copolymer and 70 to 95wt% of a dispersed styrene-butadiene latex, which has excellent plastic deformation resistance characteristics while preventing the occurrence of low-temperature cracking. However, as described hereinbefore, since this technique has a disadvantage that it requires evaporation of water to recover the elastomer, the above-mentioned problems are generated in some cases, particularly when the asphalt is modified at a high temperature exceeding 100 ℃. In addition, their use requires large amounts of polymer latex emulsions, which affects the final operating costs in view of the fact that the solids content of these materials fluctuates at levels below 70%.

Us patent 5,927,620 discloses an improved method of treating crumb rubber particles for use in asphalt compositions, which is characterized by activating the particles to enhance the rheological properties of the particles. A slurry of crumb-like rubber particles is formed by adding water thereto. The slurry is heated to 85-90 ℃ to release excess oil and chemicals from the particles into the slurry. The slurry is dried to produce a fine particle rubber product having enhanced rheological properties. The disadvantage of this material is that it is no longer an original ecological material but a crosslinked material mixed with additives, such as carbon black, which is the main constituent of tire formulations.

Also, U.S. patent 6,884,831 relates to modified asphalt using a partitioning agent and a method of making the same, characterized by preventing rubber re-aggregation by adding the partitioning agent to a polymer modifier material such as synthetic rubber. The composition of the partitioning agent is quite complex and includes a mixture of phenolic resin (phenol formaldehyde resins) and wax. Although the time required to disperse the modifier material in the asphalt using such a partitioning agent is reported to be shortened and the viscosity of the modified asphalt is reported to be reduced, this technique requires high temperatures for the partitioning agent to be incorporated into the polymer, and because of the resin and wax included therein, its use in emulsions and incorporation of the polymer feedstock during normal production processes becomes costly and difficult, because the additives are incompatible with water, and obviously very difficult to emulsify, thereby making the overall process more expensive due to the energy requirements for incorporating the polymer and the need to add other treating agents and additives for asphalt applications.

The same disadvantages are also found in us patent 7,371,794 and 7,847,006, which mention the same type of separating agent comprising phenolic resin and wax, the latter patent also incorporating precipitated silica. Obviously, the disadvantages of these additives, including waxes and resins, have become quite common, with the preferred temperature for adding the partitioning agent to the polymer exceeding 100 ℃, and the preheating step necessary to increase the flowability of the resin and wax.

Also, U.S. patent application 2010/0187718 relates to a process for preparing modified polymers characterized by re-encapsulating (re-encapsulating) the polymer by extrusion using a cross-linking agent which is mixed with particulate synthetic rubber material to form a mixture which is then heated and conveyed to an extruder. The extruder further heats the mixture to produce strands of the modified polymeric material, which are then cooled and pelletized to form small re-encapsulated modified polymeric particles. The same type of partitioning or antiblocking agents described in other patents, namely phenolic resins and waxes, are added to the pellets to prevent reaggregation of the modified polymer.

The modifier materials or anti-blocking additives described in the above-mentioned U.S. patents have properties capable of solving the problem of agglomeration of raw elastomer particles, but many problems are generated during the preparation process due to the resin and wax contained therein, problems in a drying system during the production of the elastomer due to the temperature used, and an increase in internal pressure and the need for more additives or treatments, so that the application thereof will be very difficult and expensive.

Thus, there is no suggestion or description in the prior art of a raw elastomeric composition in free-flowing pellet form that, in addition to allowing commercialization, storage and application in pellet form, can enhance the performance of rubber for further applications, while maintaining the performance of the elastomeric composition as an asphalt modifier, or adhesive, or for typical rubber applications, despite the use of antiblocking or partitioning agents. Furthermore, there is no technology that allows the incorporation of antiblocking or partitioning agents without further treatment or the use of more additives, while at the same time not compromising the properties of the elastomer in the final application, achieving antiblocking effect over long-term storage and at higher weights, thus allowing commercialization in the form of crumbs, pellets or granules.

Summary of The Invention

Object of the Invention

In view of the drawbacks of the prior art, the object of the present invention is to provide a raw elastomeric composition in free-flowing granular form which can be obtained, stored and commercialized in free-flowing granular form, allowing to maintain this form for a long time during transport and use, without recompression and avoiding the formation of large lumps which are difficult to apply.

Furthermore, it is another object of the present invention to provide a raw elastomeric composition in free-flowing granular form, such that it enhances certain properties when used in some applications, without further treatment or use of additives, in addition to maintaining the desired properties of the raw material in the final application stage.

It is another object of the present invention to provide a raw elastomeric composition in free-flowing granular form, which can be used in smaller quantities than other compositions used in the same applications of the prior art.

It is another object of the present invention to provide a process for obtaining free-flowing granular elastomeric compositions which can be easily used in emulsifying applications without the need for heating during the production of the raw elastomeric compositions, without the need for the use of waxes or complex additives, but which allows easy further processing in the final applications such as bitumen, bitumen emulsions, additives or rubber molding.

It is another object of the present invention to provide modified bitumen with enhanced mechanical properties by the addition of a free-flowing green particulate elastomer composition, including its use in bitumen emulsions.

It is another object of the present invention to provide adhesive compositions whose adhesive properties remain above the minimum parameters required for application as adhesives, but are free-flowing, granular and do not exhibit aggregation.

All the above objects are achieved by a raw elastomeric composition comprising an elastomer having a molecular weight of 50000 to 400000Da and an anti-blocking agent comprising an emulsifiable inorganic filler. The process for obtaining this composition comprises the step of adding an anti-blocking agent in the final drying stage of the raw elastomer, wherein the anti-blocking agent can be added in emulsion or solid form, incorporated without pre-treatment or additional heating.

Brief description of the drawings

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as other objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

fig. 1 is a block diagram showing the sequence of steps of a process developed according to the present invention to obtain a raw elastomeric composition in free-flowing granular form.

Fig. 2 shows the maximum Rheological Failure Temperature (RFT) of several embodiments of the raw elastomeric composition in free-flowing granular form.

Fig. 3 shows the maximum Rheological Failure Temperature (RFT) of an additional embodiment of the free-flowing particulate elastomer composition.

Detailed Description

Although inorganic fillers normally affect the properties of elastomeric compositions, by using emulsifiable inorganic fillers, the present invention can provide free-flowing particulate elastomeric compositions that can be obtained, stored and commercialized in free-flowing particulate form, can maintain this form for long periods of time during transport and use without recompression, and can enhance some properties when used in some applications without further treatment or use of additives, in addition to maintaining the desired properties of the raw materials in the end application.

According to the principle of the present invention, the raw elastomeric composition in free-flowing granular form comprises:

a) a raw elastomer having a molecular weight of 50,000 to 400,000 Da; and

b) from 0.1% to 15% by total weight of an antiblocking agent comprising an inorganic filler capable of forming an emulsion in water.

The term "raw elastomer" as used herein refers to any elastomer obtained from the polymerization process without being crosslinked, vulcanized or chemically treated.

In a preferred embodiment of the invention, the elastomer is selected from the group consisting of solution-SBR, emulsion-SBR, SB diblock copolymer and tapered triblock copolymer, but styrene-butadiene copolymers with butadiene contents above 60% by weight are particularly preferred.

Tapered triblock copolymers include, but are not limited to, elastomers and thermoplastic elastomers made from block copolymers of styrene (S), butadiene (B), and/or isoprene (I) of varying sizes and number of blocks. Examples of such elastomers and thermoplastic elastomers include (S/B-rich) - (B/S-rich) -S, (S/I-rich) - (I/S-rich) -S, (S/B) -S, (S/I) -S, (S/B) m-S and (S/I) m-S (wherein m is an integer), S- (S/B-rich) - (B/S-rich) -S, S- (S/I-rich) - (I/S-rich) -S, S- (B/S-rich) - (S/B-rich) - (B/S-rich) -S, S- (I/S-rich) - (S/I-rich) - (I/S-rich) -S, [ S- (B/S-rich) - (S/B-rich) ] n-X, [ S- (I/S-rich) - (S/I-rich) ] n-X, x- [ S- (B/S-rich) - (S/B-rich) ] n, X- [ S- (I/S-rich) - (S/I-rich) ] n (wherein X is the residue of a coupling agent or a polyfunctional initiator and n is an integer from 2 to about 30) tapered triblock copolymers and their hydrogenated, selectively hydrogenated and partially hydrogenated counterparts. These tapered triblock copolymers are disclosed in U.S. patent application 13/361,740, which is incorporated herein by reference.

As for the inorganic fillers contained in the anti-blocking agent, they are selected from metal carbonates, metal sulfates, metal oxides, metal hydroxides, metal aluminosilicates, alumina, silica, talc and combinations thereof, in combination with compatible emulsifiers also capable of forming an emulsion in water; the inorganic filler is preferably selected from the group consisting of calcium carbonate, magnesium sulfate, calcium oxide, titanium dioxide, calcium hydroxide, potassium aluminosilicate, calcium aluminosilicate, alumina, silica, talc, and combinations thereof, and more preferably selected from the group consisting of magnesium sulfate, titanium dioxide, calcium hydroxide, silica, potassium aluminosilicate, calcium aluminosilicate, talc, and combinations thereof; the emulsifier inorganic filler is selected from alkali metal salts of organic fatty esters having less than 20 carbon atoms (more preferably stearates).

In a particularly preferred embodiment, the antiblocking agent comprises the following components:

a)3-9% w/w calcium hydroxide;

b)0.3-1.1% w/w talc;

c)0.5-2% w/w titanium dioxide;

d)0.3-1% w/w calcium aluminosilicate;

e)0.2-0.7% w/w potassium aluminosilicate

f)0.5-1.5% w/w magnesium sulphate;

g)75-85% w/w silica; and

h)7-11% w/w calcium stearate.

Antiblocking agents in powder form or in the form of water-based emulsions having a content of from about 5% by weight to about 50% by weight can be used. In a specific embodiment of the invention, 2 to 8% by weight of antiblocking agent is added.

The raw elastomer composition in free-flowing pellet form of the present invention has a maximum particle size of 2 inches and a melt flow index of 3 to 13.1 grams/10 minutes measured at 190 deg.C, 2.16kg and 5kg at 200 deg.C, respectively, and requires a maximum of 15 kgf to recover to pellet form after a continuous 90 hour application of 2.76 kgf at 50 deg.C.

The process for obtaining the raw elastomeric composition in free-flowing granular form of the present invention, as shown in FIG. 1, comprises the following steps:

a) polymerizing at least one monomer by a solution polymerization process to obtain elastomer crumbs;

b) forming an aqueous suspension of elastomer crumbs to remove polymerization solvent and residue;

c) dewatering the aqueous suspension to a maximum water content of 25 wt.%;

d) adding from 0.1% to 15% of an antiblocking agent comprising an inorganic filler capable of forming an emulsion in water;

e) drying the dehydrated suspension until the maximum water content reaches 1%; and

f) the elastomer was micronized to form a raw elastomer composition in free-flowing granules with a maximum particle size of 2 inches.

The polymerization and suspension steps in the process are well known in the art, and the specific conditions for polymerization and suspension are readily known to those skilled in the art and depend on the end use of the resulting elastomer.

In a particularly preferred embodiment of the invention, the dewatering step is carried out by using an extrusion apparatus of the single-screw mandrel type, in which the screw cap is provided with ribs (rib) in the lower part of the extrusion apparatus, partially open to drain the water extruded, but without draining the wet elastomeric blocks.

Likewise, the drying step is performed through an extrusion process. The antiblocking additive is preferably added via the hopper of the extrusion apparatus. For the drying step, a single-screw extrusion apparatus with variable configuration is particularly preferred.

In a preferred embodiment where the drying step employs an extrusion process, the elastomer exiting the extruder is immediately pelletized and the resulting pellets are then optionally further dried, preferably by a fluidized bed process employing hot air.

In other embodiments of the invention, the finally obtained pellets are again sprayed with the antiblocking additive in the form of an emulsion having a solids content of from about 5% to about 50% by weight.

The raw elastomeric composition in free-flowing granules of the present invention can be packaged in bags or cartons, up to 1 ton; its shape will remain for at least one year, during which time it is free flowing and will not re-agglomerate.

The raw elastomeric composition in free-flowing granular form of the present invention can be used as an adhesive composition which maintains its adhesive properties above the minimum parameters required for adhesive application, even when it is in free-flowing granular form and does not agglomerate, despite the fact that it contains inorganic compounds. In addition, the raw elastomer composition in free-flowing pellet form of the present invention can be used to obtain modified asphalt by adding 1 to 6% by weight of said raw elastomer composition in free-flowing pellet form to asphalt. The modified bitumen thus obtained has a maximum Rheological Failure Temperature (RFT) of at least 90 ℃. Furthermore, the raw elastomer composition in free-flowing pellet form of the present invention can be used to obtain a modified asphalt emulsion by adding 1 to 6% by weight of said raw elastomer composition in free-flowing pellet form to the asphalt emulsion.

Examples

Using the process of the present invention, dewatering and dry extrusion processes were performed to obtain different pellets of embodiments of the present invention containing SBR elastomers for which performance evaluations were made without the addition of antiblock additives and with varying amounts of antiblock additives. The dewatering step of all examples was carried out by means of an extrusion device of the type known as single-screw mandrel.

Further, the drying step of all examples was carried out by a single screw type extrusion apparatus having a variable configuration, the elastomer leaving the extruder was immediately pelletized, and the obtained pellets were dried by hot air for fluidized bed process, except for examples 1 and 3.

Example 1-raw elastomer without antiblocking agent.

The SBR elastomer was obtained as described above, using a molecular weight of 109,000 daltons and a monomer ratio of 25/75 styrene/butadiene, but no antiblocking agent was used in the process. The material obtained in this example was designated as E1, characterized and used as a comparative reference in the test.

Example 2-raw elastomer containing antiblocking agent of the invention.

The SBR elastomer was obtained as described in example 1, but before the drying step was carried out, an antiblocking agent was added to the extruder. The anti-blocking agent is a mixture of calcium carbonate, magnesium sulfate, calcium oxide, calcium hydroxide, potassium aluminosilicate, calcium aluminosilicate, alumina, titanium dioxide, silica and talc, in combination with sodium stearate as a compatible emulsifier. Antiblocking agents in powder form or in the form of water-based emulsions can be used and added in varying proportions. Examples 2A, 2B and 2C were carried out by this process using (on a dry matter basis) 2%, 3.5% and 6% by weight of antiblocking agent, respectively. The resulting material was further characterized and tested.

Example 3-raw elastomer without antiblocking agent.

The SBR elastomer was obtained as described above, this time using a molecular weight of 240,000 daltons and a monomer ratio of 15/85 styrene/butadiene, but no antiblocking agent was used in the process. The material obtained in this example was designated as E3, characterized and used as a comparative reference in the test.

Example 4-raw elastomer containing antiblocking agent of the invention.

The SBR elastomer was obtained as described in example 3, but before the drying step was carried out, an antiblocking agent was added to the extruder. The anti-blocking agent is a mixture of calcium carbonate, magnesium sulfate, calcium oxide, aluminum oxide, titanium dioxide, silicon dioxide and talcum powder, and sodium stearate is used as a compatible emulsifier in combination. A powdery antiblocking agent was used and added in different proportions, but the extruder was a single-screw type apparatus with a variable configuration. Examples 4A, 4B and 4C were carried out by this process using (on a dry matter basis) 2%, 3.5% and 6% by weight of antiblocking agent, respectively. The resulting material was further characterized and tested.

For all the materials obtained in the examples, two "key" parameters were measured. Adhesion was first measured to determine if the material could be used in an adhesive application. Table 1 below lists the results of all material measurements:

TABLE 1 adhesion

Properties of	Specification of	E1	E2-A	E-2-B	E2-C
						Brookfield viscosity, cP at 177 ℃	Maximum 5741	5289	5301	5423	5507
Softening temperature of	Minimum 75	75	75.6	76	76.9
						Tensile force, MPa	Minimum 1.4	1.5	1.4	1.4	1.4
Initial annular adhesion, kgf	Minimum 1.59	4.08	4.22	4.31	4.40
						Peeling force, kgf	Minimum 1.81	3.81	3.76	3.72	3.63
Shearing in minutes	Minimum 33	55	52	48	44

It will be appreciated that despite the addition of antiblocking agents in accordance with the invention, even if the adhesion is impaired as expected, the parameters are still above the minimum required for the use of these elastomers as adhesives, which is unexpected since inorganic fillers generally have a severe impact on these properties.

In addition, a compression test was performed on the material sample. The test consisted of filling the volume with 628.3cm of each material of the examples³A hollow cylinder (height 12.5cm, bottom diameter 8 cm). The material was filled into a cylinder and another cylinder weighing 2.76kg was placed on the material while the whole system was held at 50 ℃ for 90 hours. After 90 hours, the force required for re-granulation was measured after taking the material out of the cylinder for all materials, with the following results:

TABLE 2 force required to separate the agglomerates formed in the compression test into granules

The compression test simulates the storage conditions of the material, i.e. for 6 months, and the weight of the material on the last layer of the material is at least 700 kg.

The results of the compression test are set forth in table 3 below.

Table 3-force required for the bulk material after compression test.

E1

E2-A

E2-B

E2-C

E3

E4-A

E4-B

E4-C

Dynamics (kgf)

>160

>40

>30

<10

>160

30-40

<15

<5

From the above results, it is apparent that the material of the present invention requires a small force to recover the granular form, equivalent to pressing the material with a finger. Thus, the material obtained according to the principles of the present invention can be stored and transported in pellets without any risk of aggregation and lump formation.

Example 5 comparative antiblocking agent

A compression test was performed on compositions (corresponding to examples 5A to 5O) comprising the SBR elastomer of example 1 and different materials used as antiblocking agents in order to compare the respective properties. The additives used were respectively: petrolite01 dispersant (E5A), micronized hydroxylated polyethylene wax (E5B), calcium stearate (E5C), industrial talc (E5D), calcium carbonate (E5E), Barbe237 (emulsified calcium carbonate) (E5F), erucamide (E5G), oleamide (crodamide) (E5H), talc (E5I), gilsonite (E5J), diatomaceous earth (E5K), reagent a (E5L), reagent B (E5M), Aquastab reagent (pulverized micronized polyethylene) (E5N) and the additive of the invention (E5O). The results are shown in Table 4:

TABLE 4-Performance of some antiblock additives in compression testing

From the above, it can be seen that the materials of the present invention require less force to recover the particulate state after compression testing than elastomers modified with other antiblocking agents.

Now, in order to measure the properties of the materials of the present invention, these materials were tested as asphalt modifiers. Adding the material to asphalt grade AC-20 with a permeability of 60-801/10mm at 25 ℃; the temperature was raised to 170 ℃ and 195 ℃ and the stirring was carried out at a rate of 600 revolutions per minute.

Table 5-results for modified asphalts of sample 1 and 2SBR block copolymers (styrene-butadiene ratio of 25/75) and SBR pellets with antiblock additives.

As can be seen from the results in table 5, the additives do not affect the main thermo-mechanical properties. For example, a torsional elastic recovery at 25 ℃ indicates that the additive improves this property even slightly, with most parameters such as permeability, viscosity, and diffusion time improving, or consistent with typical block elastomers used in the prior art without the addition of antiblocking agents. In the specific case of viscosity, the SHRP-SUPERPAVE standard specifies a maximum permissible viscosity of 3000cP at 135 ℃, which is achieved in all cases.

The highest Rheological Failure Temperature (RFT) of the samples was also tested. This refers to the following temperatures: at this temperature, the ratio of the deformation angle of the asphalt divided by the complex modulus or hardness is less than or equal to 1kPa, which is the basic rheological specification of the modified asphalt.

The RFT with different amounts of polymer composition according to the invention is shown in figure 2. It is readily seen that the required high temperatures can be achieved with the very small amounts of the polymer composition of the present invention, which indicates that the antiblock agent used to maintain the pellet shape not only does not destroy the properties of the asphalt, but the composition also improves its properties because less elastomer is required to achieve the same RFT, which is set at 66 ℃ for very demanding applications such as airport asphalt.

The same tests were carried out for examples 3 and 4 and the results are shown in Table 6 and FIG. 3, which also show that the composition of the invention as a modifier does not affect the properties of the bitumen but improves some of the properties of the modified bitumen.

TABLE 6-results for the 240000Da SBR block copolymer (styrene-butadiene ratio of 15/85) and SBR pellets with antiblock additive of examples 3 and 4.

Example 6 bitumen emulsion

The materials of the present invention were tested and compared to conventional products of asphalt emulsions for chip encapsulants. The materials evaluated were EVA (E6A), butonal (E6B), the SBR elastomer of example 1 (E6C and E6D) and the materials obtained in examples 2A and 2B (E6E and E6F).

The results are shown in Table 7.

TABLE 7 results for bitumen emulsions for chip encapsulants

From the results of table 7, it can be seen that the additives do not affect the characteristics of the asphalt emulsion used for the chip encapsulant, but, on the contrary, improve the adhesion properties even when a smaller amount of the material of the present invention is used, as compared to the products conventionally used for this purpose.

Therefore, the invention should not be construed as limited to the examples only, since many variations of different elastomers or specific compositions, such as the antiblocking agents used in the invention, have been adequately described in the specification. Accordingly, the invention is to be limited only by the scope of the following claims.

Claims (25)

1. A raw elastomeric composition in free-flowing particulate form comprising:

a) a raw elastomer having a molecular weight of 50,000 to 400,000 Da; and

b) from 1% to 15% by total weight of an antiblock agent comprising an inorganic filler capable of forming an emulsion in water, wherein the antiblock agent is not applied as an outer layer of a free-flowing granular composition.

2. The elastomeric composition according to claim 1, wherein the elastomer is selected from the group consisting of solution SBR, emulsion SBR, SB diblock copolymer and tapered triblock copolymer.

3. The elastomeric composition according to claim 2, wherein said elastomer is a styrene-butadiene copolymer having a butadiene content higher than 60% w/w.

4. Elastomeric composition according to claim 1, wherein the inorganic filler comprised in the anti-blocking agent is selected from the group consisting of metal carbonates, metal sulfates, metal oxides, metal hydroxides, metal aluminosilhchloric acids, silicas, talc and combinations thereof, in combination with a compatible emulsifier also capable of forming an emulsion in water.

5. The elastomeric composition according to claim 4, wherein the inorganic filler comprised in the antiblocking agent is selected from the group consisting of calcium carbonate, magnesium sulfate, calcium oxide, titanium dioxide, calcium hydroxide, potassium aluminosilicate, calcium aluminosilicate, alumina, silica, talc and combinations thereof.

6. The elastomeric composition according to claim 5, wherein the inorganic filler comprised in the antiblocking agent is selected from the group consisting of magnesium sulfate, titanium dioxide, calcium hydroxide, silica, potassium aluminosilicate, calcium aluminosilicate, talc and combinations thereof.

7. The elastomeric composition according to claim 4, wherein the compatible emulsifier is selected from the group consisting of alkaline salts of organic fatty acid esters of less than 20 carbon atoms.

8. The elastomeric composition according to claim 7, wherein the compatible emulsifier is a stearate.

9. The elastomeric composition according to claim 1, wherein the antiblocking agent comprises:

a)3-9% w/w calcium hydroxide;

b)0.3-1.1% w/w talc;

c)0.5-2% w/w titanium dioxide;

d)0.3-1% w/w calcium aluminosilicate;

e)0.2-0.7% w/w potassium aluminosilicate

f)0.5-1.5% w/w magnesium sulphate;

g)75-85% w/w silica; and

h)7-11% w/w calcium stearate.

10. The elastomeric composition according to claim 1, wherein the anti-blocking agent can be used in powder form or as a water-based emulsion having a solids content of 5 to 50% by weight.

11. The elastomeric composition according to claim 1, wherein the anti-blocking agent is added at 2 to 8% by weight.

12. The elastomeric composition according to claim 1, wherein the maximum particle size of the particles is 2 inches.

13. The elastomeric composition according to claim 1, wherein the melt flow index of the composition is from 3 to 13.1 g/10 min.

14. The elastomer composition according to claim 1, wherein a force of up to 120kgf is required to loosen the composition into particles after a continuous application of 2.76kg of pressure at 50 ℃ for 90 hours.

15. A process for the preparation of a raw elastomeric composition in free-flowing granular form according to claim 1, comprising the steps of:

a) polymerizing at least one monomer by a solution polymerization process to obtain elastomer crumbs;

b) forming an aqueous suspension of elastomer crumbs, removing polymerization solvent and residues;

c) dewatering the aqueous suspension to a maximum water content of 25 wt.%;

d) adding from 1% to 15% of an antiblocking agent comprising an inorganic filler capable of forming an emulsion in water;

e) drying the dehydrated suspension until the maximum water content reaches 1%; and

f) granulating the elastomer to form a green elastomer composition in free-flowing granular form having a maximum particle size of 2 inches,

wherein the antiblocking agent is not applied as an outer layer of a free-flowing particulate composition.

16. The process for the preparation of an elastomeric composition according to claim 15, wherein said dehydration step is carried out by means of an extrusion device of the type known as single-screw mandrel.

17. The method of preparing an elastomeric composition according to claim 15, wherein said drying step is performed by an extrusion process.

18. The process for preparing an elastomeric composition according to claim 16, wherein said drying step is carried out by means of a single screw extrusion device with variable configuration.

19. The process for preparing an elastomeric composition according to claim 16, wherein said elastomeric composition is additionally dried in a further step by fluidized bed using hot air.

20. An adhesive composition comprising the composition according to claim 1.

21. The adhesive composition of claim 20, wherein the brookfield viscosity at 177 ℃ is at most 5741cP, the softening temperature is at least 75 ℃, the tension is at least 1.4MPa, the loop tack force is at least 1.59lbf, the peel force is at least 1.81lbf, and the shear is at least 33 minutes.

22. A modified asphalt emulsion comprising an asphalt emulsion and an elastomer, wherein the elastomer is the raw elastomer composition in free-flowing pellet form according to claim 1.

23. A modified asphalt emulsion according to claim 22, wherein a small amount of the elastomer composition is used in order to achieve the same adhesion as the asphalt emulsion.

24. A modified asphalt comprising asphalt and an elastomer, wherein the elastomer is the raw elastomer composition in free-flowing pellet form according to claim 1.

25. The modified asphalt of claim 24, wherein the maximum Rheological Failure Temperature (RFT) is at least 90 ℃ when processing the modified asphalt.