A method of producing a composite material comprising a bitumen, polyethylene and polystyrene, composite material and use of said composite material

Abstract

Present invention relates to a method of producing a composite material comprising a bitumen, polyethylene and polystyrene, composite material and use of said composite material. Said composite material comprises 70-90 percent by weight of bitumen, 10-30 percent by weigh of polyethylene, and 3-10 percent by weigh of polystyrene. The method comprises steps wherein in a reaction vessel the bitumen is heated to a temperature of 160-180°C under agitation, a shredded or granulated polyethylene and polystyrene are added to the molten bitumen under continuous agitation, a reaction temperature of the mixture is maintained for period of 0.5 to 4 hours to facilitate a copolymerization reaction.

Description

[0001] A method of producing a composite material comprising a bitumen, polyethylene and polystyrene, composite material and use of said composite material

[0002] Technical Field

[0003] The present invention relates to a composite material formed through the blending and copolymerization of bitumen, polyethylene, and polystyrene. More specifically, the invention concerns a method for producing a composite material that incorporates these elements, a composite material obtained through said method, and its subsequent applications. This composite material exhibits enhanced mechanical properties, such as superior flexibility, tensile strength, and weather resistance, making it suitable for various construction and industrial purposes. The material is particularly advantageous for use in roofing membranes, waterproofing layers, roof-building elements, and road surfacing, where durability and resistance to environmental factors are critical.

[0004] Background Art

[0005] Bitumen has been widely used in construction, particularly for waterproofing and as a binder in road surfaces, due to its adhesive properties and resistance to water. However, bitumen alone can be brittle at low temperatures and soften excessively at high temperatures, which limits its range of applications.

[0006] Bitumen-based roofing materials (BBRM) are commonly used in the construction industry for their durability, weather resistance, and flexibility. These materials are available in two forms: modified bitumen membranes (MBR) and built-up roofing (BUR) systems. BUR systems consist of alternating layers of bitumen and reinforcing fabrics, such as felt or fiberglass, which are then topped with gravel or other surfacing materials to create a waterproof and durable roof.

[0007] MBRs, on the other hand, involve bitumen that is mixed with synthetic rubbers or plastics, such as SBS (styrene-butadiene-styrene) or APP (atactic polypropylene). These blends improve the flexibility and durability of bitumen, but recycling bitumenbased materials remains a challenge. Current recycling methods are limited to crushing and mixing old roofing materials with asphalt for road construction or burning them for energy

[0008] Polyethylene and polystyrene are polymers known for their flexibility, strength, and resistance to various chemicals. Polyethylene, in particular, is noted for its toughness and ductility, while polystyrene offers rigidity and impact resistance. Used plastics can be shredded and reformed into new products. Unfortunately, the recycling degrades the material’s quality due to heat exposure.

[0009] The present invention seeks to overcome these limitations by combining bitumen with polyethylene and polystyrene through a co-blending and copolymerization process. This process results in a composite material that incorporates the beneficial properties of each component, producing a product that is more versatile and durable than bitumen alone.

[0010] Current technologies involving bitumen modification include various polymer blends that improve specific properties of bitumen. Notable among these are:

[0011] APP-Modified Bitumen: This blend uses atactic polypropylene (APP), a plastic that melts at approximately 160°C, transforming into a liquid wax-like substance. This ease of melting makes APP-modified bitumen popular for residential and small commercial roofing applications, offering a user-friendly experience due to its high- temperature tolerance.

[0012] SBS-Modified Bitumen: SBS-modified bitumen incorporates styrene-butadiene- styrene (SBS), which provides a ‘sticky’ melt rather than a free-flowing liquid. This type of bitumen requires less heat during installation, leading to faster application times. The synthetic rubber in SBS enhances the flexibility and stress recovery of the material, making it more resistant to environmental stressors like wind and temperature fluctuations.

[0013] Ethylene Copolymer Bitumen (ECB): ECB is a blend based on high-quality polyethylene copolymers mixed with various bitumen grades. This combination provides a material that maintains a balance between flexibility and durability, making it suitable for a variety of applications.

[0014] Bitumen with Polyethylene: At elevated temperatures (around 50°C), blends of bitumen with high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) have demonstrated improved flow characteristics and mechanical stability. Increasing the proportion of HDPE has been shown to elevate the temperature of onset of flow from 80°C to 120°C. This demonstrates the ability of polyethylene to enhance the performance of bitumen under thermal stress.

[0015] Despite these advancements, there remains a need for a composite material that combines the best properties of these existing technologies while offering improved performance characteristics, particularly in terms of flexibility, tensile strength, and environmental resistance.

[0016] Disclosure of Invention

[0017] Present invention provides a method for producing a composite material. More specifically present invention provides a composite material produced by the blending and copolymerization of bitumen, polyethylene, and polystyrene. The copolymerization process is carried out under controlled conditions to ensure a uniform mixture, resulting in a material with superior mechanical properties. The composite material demonstrates increased flexibility, enhanced tensile strength, and improved resistance to ultraviolet (UV) radiation and environmental degradation compared to standard bitumen.

[0018] Key features of the invention include:

[0019] Composition: The composite material comprises 70-90% bitumen, 10-30% polyethylene, and 3-10% polystyrene by weight.

[0020] Process: The copolymerization process involves heating the bitumen to a fluid state and gradually adding polyethylene and polystyrene under agitation. A catalyst may be used to facilitate the copolymerization reaction, ensuring even distribution of polymers within the bitumen matrix.

[0021] The process results in a spatial matrix structure, where long PE chains are connected with short PS chains, significantly increasing the material's strength and elasticity. Bitumen particles are located in the voids of the resulting matrix, weakly bonded to the plastic through individual links. In general, the process can be carried out by simply crushing and pulverizing the raw materials and heating them to a temperature of 200-280°C. Catalysts (such as such as a peroxide or a transition metal complex, clays, etc.) can significantly accelerate the process, that is to facilitate the copolymerization reaction.

[0022] Properties: The combination of polyethylene and polystyrene greatly enhances the elasticity of the material while reducing its flowability, compared to previous solutions. This is attributed to the formation of a network structure that helps maintain the integrity of bitumen crystallites. Additionally, the material exhibits a higher melting point and significantly improved elongation at break, making it suitable for applications requiring flexibility at both high and low temperatures.

[0023] Applications: The composite material is particularly suitable for use in roofing, waterproofing membranes, roof details and road surfacing. Its enhanced durability and weather resistance make it ideal for environments subject to extreme temperature variations and UV exposure.

[0024] Technical Problem

[0025] During roof renovations, large quantities of waste bitumen-based roofing materials (BBRM) are generated. Unfortunately, the recycling possibilities for these materials have been quite limited. Typically, they are either crushed and mixed with asphalt for road construction or burned for energy recovery. While waste plastic materials, such as polyethylene and polystyrene, can be recycled, the process of re-melting significantly degrades their durability and mechanical properties.

[0026] Given these challenges, there is a need for a more effective recycling method that not only reuses BBRM but also enhances the properties of the recycled materials, making them suitable for high-performance construction applications.

[0027] Technical Solution

[0028] The present invention addresses these recycling limitations by providing a composite material with properties that are, in many respects, superior to the original materials. The resulting composite is durable, weather-resistant, and exhibits exceptionally high mechanical strength. Additionally, the process for producing this material is straightforward and can be carried out directly at the renovation site using a portable device.

[0029] Present invention provides a method of producing a composite material comprising 70-90% by weight of bitumen, 10-30% by weight of polyethylene, and 3-10% by weight of polystyrene. The method includes the following steps: in a reaction vessel the bitumen is heated to a temperature of 160-180°C under agitation, a shredded or granulated polyethylene and polystyrene are added to the molten bitumen under continuous agitation, a reaction temperature of the mixture is maintained for period of 0.5 to 4 hours to facilitate a copolymerization reaction.

[0030] In another embodiment of the invention to facilitate the copolymerization reaction, a catalyst, comprising a peroxide or a transition metal complex, is introduced to the mixture.

[0031] In another embodiment of the invention, the polyethylene is a recycled polyethylene.

[0032] In another embodiment of the invention, the polystyrene is a recycled polystyrene, expanded polystyrene or mixture of thereof.

[0033] In another embodiment of the invention, the bitumen is recycled bitumen, recycled bitumen binder roofing material or mixture of thereof.

[0034] Present invention also provides a composite material comprising a bitumen, polyethylene, and polystyrene produced according to method of the invention.

[0035] Present invention also provides a use of the composite material produced according to method of the invention in the manufacture of roofing membranes, roof details and waterproofing layers, or road surfaces.

[0036] Advantageous Effects

[0037] The invention described herein offers several advantages over traditional bitumen- based materials and existing recycling methods. By incorporating polyethylene and polystyrene through a copolymerization process, this novel composite material overcomes many of the limitations associated with pure bitumen and conventional bitumen-based roofing materials (BBRM).

[0038] Key Benefits:

[0039] 1. The combined use of polyethylene and polystyrene significantly increases the elasticity of the material. This enhanced flexibility allows the composite to perform better under mechanical stress, making it more resistant to cracking and deformation under varying environmental conditions.

[0040] 2. The copolymerization process results in a material that is highly resistant to weathering and environmental degradation. It is particularly effective in resisting ultraviolet (UV) radiation, which is a common cause of deterioration in roofing and construction materials. This leads to a longer lifespan for structures that use the composite material.

[0041] 3. While conventional bitumen tends to soften and flow under high temperatures, the composite material reduces this issue due to the formation of a network structure that stabilizes bitumen crystallites. This ensures that the material retains its shape and mechanical properties even under extreme heat.

[0042] 4. The composite material exhibits a higher melting point than traditional bitumen, making it suitable for applications where exposure to high temperatures is expected, such as in road surfacing and roofing exposed to prolonged sunlight.

[0043] 5. The invention offers a sustainable solution to waste management in the construction industry. By utilizing recycled polyethylene, polystyrene, and bitumen, the method reduces the environmental impact associated with the disposal of these materials. Additionally, the process can be carried out on-site, reducing the need for transportation and further minimizing the environmental footprint.

[0044] 6. Tests have shown that the composite material exceeds the mechanical strength of standard bitumen by a significant margin. For example, the flexural strength of the resulting material exceeds 10 N / mm2, compared to less than 1 N / mm2for pure bitumen, while the compressive strength reaches 5-8 MPa, far surpassing the typical 0.3-0.5 MPa for bitumen.

[0045] Overall, the composite material produced by this invention is ideal for applications in roofing, waterproofing, and road surfaces, where enhanced mechanical properties and environmental resistance are critical. Its unique composition and the ease of on-site production make it a practical and cost-effective solution for both new construction and renovation projects.

[0046] Brief Description of Drawings

[0047] Figure 1 depicts the chemical structure of resulting copolymer.

[0048] Mode(s) for Carrying Out the Invention

[0049] Materials and Methods:

[0050] Bitumen: A commercially available bitumen grade is used, typically with a penetration index suitable for the desired end-use application. Shredded recycled BBRM can be used.

[0051] Polyethylene: High-density polyethylene (HDPE) is preferred for its toughness, though low-density polyethylene (LDPE) may also be used depending on the required flexibility. Recycled polyethylene can be used.

[0052] Polystyrene: General-purpose polystyrene (GPPS) is utilized to impart rigidity and improve the impact resistance of the final product. Recycled polystyrene, including EPS can be used.

[0053] Copolymerization Process:

[0054] Preparation: A bitumen is heated to a temperature of approximately 160-180°C in a reaction vessel equipped with an agitator.

[0055] Addition of Polymers: Shredded or granulated polyethylene and polystyrene are added slowly to the molten bitumen under continuous agitation to ensure even distribution. The temperature is maintained to facilitate the dissolution and mixing of the polymers. Catalysis: A catalyst, such as a peroxide or a transition metal complex, may be introduced to initiate and sustain the copolymerization reaction. The reaction is allowed to proceed for a period ranging from 0.5 to 4 hours, depending on the desired properties of the final material.

[0056] The transition metal complex in this context is for example a simple, short carbon chain with double bonds, to which one or more transition metal such as platinum, copper, nickel etc atoms are attached. They are highly efficient in organic synthesis due to their inherent properties like variable oxidation state (oxidation number), complex ion formation and catalytic activity.

[0057] Cooling and Forming: After copolymerization, the mixture is allowed to cool to room temperature, solidifying into a homogeneous material that can be processed into sheets, pellets, or other forms suitable for industrial use. Cast moulding or extruding can be used for producing 3-dimensional details.

[0058] According to test data, the flexural strength of the resulting material exceeds 10 N / mm2(compared to less than 1 N / mm2for bitumen), and the compressive strength is 5-8 MPa (typically 0.3-0.5 MPa for bitumen).

[0059] Figure 1 a depicts the chemical structure of resulting copolymer obtained by the method of the invention, where C stands for polyethylene chain, X for styrene links and B for bitumen particles.

[0060] Use of obtained composite material

[0061] Example 1 : The liquid composite material produced is poured into molds to create new construction components (e.g., walkways). After solidification, these components can be glued into the required positions using liquid bitumen.

[0062] Example 2: The liquid mixture from the processing machine is extruded to produce long construction components, such as roof slopes. The resulting strip is cut into pieces of the required length and then glued into the necessary positions.

Claims

AMENDED CLAIMS received by the International Bureau on 26 February 2026 (26.02.2026)1 . A method of producing a composite material, said composite material comprises 70-90 percent by weight of bitumen, 10-30 percent by weigh of polyethylene, and 3- 10 percent by weigh of polystyrene, said method comprises steps wherein in a reaction vessel the bitumen is heated to a temperature of 160-180°C under agitation, a shredded or granulated polyethylene and polystyrene are added to the molten bitumen under continuous agitation, a reaction temperature of the mixture is maintained for period of 0.5 to 4 hours to facilitate a copolymerization reaction, characterized in that the bitumen is recycled bitumen, recycled bitumen binder roofing material or mixture of thereof.

2. The method of claim 1 , characterized in that to facilitate the copolymerization reaction, a catalyst, comprising a peroxide or a transition metal complex, is introduced to the mixture.

3. The method of claim 1 or 2, characterized in that the polyethylene is a recycled polyethylene.

4. The method of claim 1 , 2 or 3, characterized in that the polystyrene is a recycled polystyrene, expanded polystyrene or mixture of thereof.

5. A composite material comprising a bitumen, polyethylene, and polystyrene produced according to any preceding claims 1 to 4.

6. Use of the composite material produced according to any preceding claims 1 to 4 in the manufacture of roofing membranes, roof details and waterproofing layers, or road surfaces.

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