A method of modifying HDPE float material to increase surface tension
By grafting highly active polar groups and compounding hydrophilic additives onto HDPE float materials, the problem of low surface tension in HDPE float materials is solved, achieving long-term improvement in surface tension and stable adhesion of functional coatings, making it suitable for industrial production while maintaining the core performance of the float.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI SHUIGUANG TECHNOLOGY CO LTD
- Filing Date
- 2026-03-13
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies struggle to achieve long-term, stable improvement in surface tension on HDPE float materials while maintaining the core performance of the float, and also present problems such as environmental pollution and high production costs.
Using low-temperature melt grafting blending technology, highly active polar groups are grafted onto the HDPE molecular chain. Hydrophilic additives and compatibility additives are compounded, and the intermolecular forces are enhanced through the synergistic effect of acrylic acid, benzoyl peroxide and grafting accelerator, so as to achieve precise and long-term improvement of surface tension. The stability of the modification effect is ensured by anti-migration additives.
It achieves a significant increase in the surface tension of HDPE float material, a significant improvement in surface hydrophilicity and antistatic properties, enhanced adhesion of functional coatings, and maintains stable density, water resistance, corrosion resistance, and mechanical strength of the float, making it suitable for industrial mass production, and is green, environmentally friendly, and pollution-free.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer material modification technology, and in particular to a modification method for increasing the surface tension of HDPE float material. Background Technology
[0002] HDPE molecular chains have a typical nonpolar structure, with van der Waals forces being the dominant intermolecular forces. This results in extremely low surface tension, with conventional HDPE having a surface tension of only 30-34 mN / m. It also exhibits strong surface inertness and poor hydrophilicity. In practical applications, this presents the following prominent technical challenges, severely limiting the performance upgrades and application expansion of HDPE floats.
[0003] Insufficient surface hydrophilicity can easily lead to interfacial problems. The extremely low surface tension results in a significant interfacial tension difference between the surface and water, causing water droplets to easily roll off in a spherical shape and fail to form a uniform water film.
[0004] Functional coatings suffer from poor adhesion stability. With the diversification of floating body applications, it is necessary to laminate functional layers such as hydrophilic coatings, anti-fogging coatings, antibacterial coatings, and antistatic coatings onto the surface of HDPE floating bodies to meet specific usage requirements. However, due to the low surface tension of HDPE, the functional coatings, which are mostly polar systems, have extremely weak interfacial bonding with the HDPE matrix, making them prone to delamination, peeling, and detachment, thus failing to achieve stable functional modification.
[0005] Existing improvement methods have significant drawbacks. Currently, the industry mainly attempts to increase the surface tension of HDPE through physical modification (plasma treatment, ultraviolet irradiation) and chemical modification (strong acid oxidation, polar monomer grafting). However, both methods have insurmountable shortcomings: physical modification methods have short-lasting effects (the modified surface easily returns to inertness, with an effective period of only a few days to a few weeks), poor treatment uniformity, making it difficult to adapt to the mass production of large floats, and the processing cost is high; chemical modification methods (such as strong acid oxidation) are highly corrosive, which will damage the mechanical properties of HDPE floats, causing them to become brittle and prone to cracking, while generating a large amount of waste liquid, polluting the environment, and failing to meet the requirements of green production; conventional polar monomer grafting modification is prone to uneven grafting, and it is difficult to accurately control the increase in surface tension, which can easily lead to "over-modification" and a decrease in the water resistance of the float.
[0006] In summary, existing technologies lack a simple, controllable, and environmentally friendly modification method that can achieve long-term and stable improvement in the surface tension of HDPE float materials while also taking into account the core performance of the float (buoyancy, water resistance, corrosion resistance, and mechanical strength). There is an urgent need to develop a new modification scheme to fundamentally solve the technical pain points of HDPE floats in terms of hydrophilicity, functional composites, and antistatic properties. Summary of the Invention
[0007] In view of this, the purpose of this invention is to propose a modification method to increase the surface tension of HDPE float material, thereby solving the problems in the background art.
[0008] To achieve the above objectives, the present invention provides a modification method for increasing the surface tension of HDPE floating materials, comprising the following steps: Step 1: Raw material pretreatment. Place 90.0-96.0% by weight of HDPE matrix resin in an oven to dry. Step 2, premixing: First, add the dried HDPE matrix resin, 0.5-1.5% by weight of anti-migration additive, and 0.5-1.5% by weight of compatibility additive into a high-speed mixer and mix to obtain the basic premix. Step 3: Mixing. Then, slowly add 1.5-4.0% by weight of acrylic acid, 0.3-1.0% by weight of benzoyl peroxide, 0.2-0.8% by weight of grafting accelerator, and 1.0-3.0% by weight of hydrophilic additives to a high-speed mixer and mix with the base premix to obtain the premix. Step 4, Low-temperature melt grafting: The premix is added to a twin-screw extruder. Through gentle melt shearing, benzoyl peroxide slowly decomposes to generate free radicals, which initiate a grafting reaction between acrylic acid and the HDPE matrix resin molecular chains. At the same time, hydrophilic additives, anti-migration additives, and compatibility additives are uniformly dispersed to form a modified HDPE melt. Step 5, Granulation: After the extruded strip is rapidly cooled and shaped in a cooling water tank, it is cut into modified HDPE granules with a particle size of 3-5mm by a pelletizer, and then placed in an oven to dry and remove moisture, thus obtaining modified HDPE float material.
[0009] Preferably, the oven temperature in step one is 80-90℃, and the drying time is 2-3 hours.
[0010] Preferably, in step two, the high-speed mixer operates at a speed of 800-1000 r / min, a temperature of 50-60℃, and a mixing time of 5-8 minutes.
[0011] Preferably, in step three, the high-speed mixer operates at a speed of 600-800 r / min, and the mixing time is 3-5 minutes.
[0012] Preferably, the temperatures of each section of the twin-screw extruder in step four are as follows: feeding section 130-140℃, melting section 145-155℃, grafting reaction section 155-165℃, homogenization section 150-160℃, and die head 145-155℃; screw speed 180-220 r / min, and vacuum degree -0.06~-0.08 MPa.
[0013] Preferably, in step five, the water temperature in the cooling water tank is 20-30℃, the oven temperature is 80℃, and the drying time is 2 hours.
[0014] Preferably, the mass percentage of the HDPE matrix resin in step one is 92.0-94.5%; In step two, the mass percentage of the anti-migration agent is 0.8-1.2%, and the mass percentage of the compatibility agent is 0.8-1.2%. In step three, the mass percentage of acrylic acid is 2.0-3.0%, the mass percentage of benzoyl peroxide is 0.4-0.7%, the mass percentage of grafting accelerator is 0.3-0.5%, and the mass percentage of hydrophilic additive is 1.5-2.5%.
[0015] Preferably, the anti-migration agent is polymethyl methacrylate; the compatibility agent is HDPE-g-AA with a grafting rate of 1.5-2.0%; the grafting promoter is triethanolamine; and the hydrophilic agent is polyethylene glycol monomethyl ether acrylate.
[0016] The beneficial effects of this invention are as follows: This invention overcomes the shortcomings of existing physical and chemical modifications by adopting a synergistic modification scheme of "polar monomer grafting reinforcement + high-efficiency hydrophilic additive compounding + interface compatibility regulation". By grafting highly active polar groups onto the HDPE molecular chain and compounding with special hydrophilic and compatibility additives, the surface chemical composition of HDPE float material is changed at the molecular level, enhancing intermolecular forces and achieving a precise, long-lasting, and stable increase in surface tension. At the same time, the modification process and ratio are strictly controlled to ensure that the core properties of the modified HDPE float material, such as density, water resistance, corrosion resistance, and mechanical strength, do not decrease.
[0017] A dedicated high-activity grafting system is designed to precisely enhance surface tension. Acrylic acid is selected as a highly active polar grafting monomer, benzoyl peroxide is used as a low-temperature initiator, and a small amount of grafting promoter (triethanolamine) is added. Through melt grafting, a large number of carboxyl (-COOH) polar groups are grafted onto the HDPE molecular chain, breaking the non-polar structure of the HDPE molecular chain, enhancing the hydrogen bonding and polar interaction between molecules, and fundamentally improving surface tension.
[0018] The synergistic formulation of hydrophilic additives enhances the surface tension boosting effect and maintains its long-lasting effect. The formulation combines a specialized hydrophilic additive, polyethylene glycol monomethyl ether acrylate, with an anti-migration additive, polymethyl methacrylate. The hydrophilic additive further enhances the hydrophilicity of the HDPE float surface, assisting in increasing surface tension; the anti-migration additive effectively inhibits the migration and precipitation of grafted monomers and hydrophilic additives to the float surface, ensuring long-term stability of the surface tension boosting effect and preventing the surface tension from decaying during prolonged immersion in water. It also improves the water resistance stability of the float surface.
[0019] Interface compatibility control balances surface modification with core float performance. A specialized compatibility additive (HDPE-g-AA, grafting rate 1.5-2.0%) is introduced to improve the interfacial bonding between the polar graft monomer, hydrophilic additive, and HDPE matrix. This addresses the problem of poor compatibility between polar components and HDPE, leading to decreased mechanical properties, in existing modification schemes. This ensures that while significantly improving surface tension, the float's density, water and corrosion resistance, mechanical strength, and other core properties remain stable.
[0020] Integrated process design, suitable for industrial mass production. Graft modification, additive compounding, and HDPE float molding processes are deeply integrated. Using a conventional twin-screw extruder for melt blending and grafting, modified HDPE float-specific materials are directly prepared without additional surface treatment. Float products can be directly manufactured through conventional processes such as injection molding, blow molding, and rotational molding, simplifying the production process, reducing production costs, and ensuring easy control of process parameters and good uniformity. It is suitable for mass production of small, medium, and large HDPE floats, solving the problems of complex and difficult-to-scale application of existing modification processes.
[0021] This invention takes into account the core performance of the float, with no performance loss and even a slight improvement: by precisely controlling the modification ratio and low-temperature grafting process, while achieving a significant increase in surface tension, it ensures that the core performance of the modified HDPE float material is basically the same as that of the unmodified HDPE, with no obvious loss. The surface tension enhancement effect is significant, precise, and long-lasting: By enhancing the surface polarity of HDPE at the molecular level through AA grafting modification, and with the synergistic effect of hydrophilic additives, the surface tension of HDPE float materials can be increased by 32%-62%, significantly improving surface hydrophilicity and antistatic properties. At the same time, through the regulation of anti-migration additives and compatibility additives, the grafted groups are firmly bonded to the HDPE molecular chain, making it difficult for the additives to migrate and precipitate. When the float is immersed in water for a long time (more than 30 days), the surface tension change rate is ≤3%, and the modification effect is long-lasting and stable, completely solving the problem of easy decay of the effect of existing physical modification.
[0022] The process is simple and suitable for industrial mass production: It adopts the "low temperature melt grafting + floating body integrated molding" process, which eliminates the need for additional surface treatment processes (such as plasma treatment, flame burning, strong acid oxidation), simplifies the production process and reduces production costs. Green and environmentally friendly, with no pollution and safe and controllable: It abandons the corrosive process of existing chemical modification (strong acid oxidation). The entire modification process generates no waste liquid, waste gas, or waste residue. All raw materials used are environmentally friendly additives with no toxic or harmful substances, which meets the requirements of green production. At the same time, it adopts a low-temperature grafting process to avoid the smoke pollution generated by high temperature. The production process is safe and controllable, reducing the environmental treatment costs and safety hazards in the production process.
[0023] With wide adaptability, the application scenarios of floating bodies are expanded: the modified HDPE floating bodies have high surface tension, good hydrophilicity, and strong interfacial bonding force, and can be directly processed with functional composites such as hydrophilic coating, anti-fog coating, antibacterial coating, and antistatic coating without complicated surface pretreatment. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.
[0025] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0026] This embodiment provides a method for modifying HDPE float material to increase surface tension, comprising the following steps: S1, raw material pretreatment: 93.0% by mass of HDPE matrix resin is placed in an oven for drying. The MFR of HDPE matrix resin is 1.5g / 10min, the density is 0.945g / cm³, the oven temperature is 85℃, and the drying time is 3 hours. S2, Premix: First, add the dried HDPE matrix resin, 1.0% by mass of polymethyl methacrylate, and 0.5% by mass of HDPE-g-AA to a high-speed mixer to mix and obtain the basic premix. The speed of the high-speed mixer is 9000 r / min, the temperature is 60℃, and the mixing time is 8 minutes. S3, mix, then slowly add 2.5% by mass of acrylic acid, 0.6% by mass of benzoyl peroxide, 0.4% by mass of grafting accelerator, and 2.0% by mass of hydrophilic additive to a high-speed mixer and mix with the base premix to obtain the premix. The high-speed mixer speed is 600-800 r / min, and the mixing time is 3-5 minutes. S4, Low-temperature melt grafting blending: The premixed material is added to a twin-screw extruder. The temperatures of each section of the twin-screw extruder are as follows: feeding section 140℃, melting section 155℃, grafting reaction section 165℃, homogenization section 160℃, and die head 155℃; the screw speed is 220 r / min, and the vacuum degree is -0.08 MPa. Through gentle melt shearing, benzoyl peroxide slowly decomposes to generate free radicals, which initiates a grafting reaction between acrylic acid and the HDPE matrix resin molecular chains. At the same time, hydrophilic additives, anti-migration additives, and compatibility additives are uniformly dispersed to form a modified HDPE melt. S5, Granulation: The extruded strip is rapidly cooled and shaped in a cooling water tank at a temperature of 30°C. Then, it is cut into modified HDPE granules with a particle size of 5mm by a pelletizer. The granules are then placed in an oven to dry and remove moisture at a temperature of 80°C for 2 hours to obtain modified HDPE float material.
[0027] The performance of the prepared modified HDPE float material was tested according to the following standards: Surface tension: Tested according to GB / T 14216-2008, using the contact angle measurement method to calculate the surface tension value; Surface hydrophilicity: The contact angle of a water droplet on the surface of the float is measured. The smaller the contact angle, the better the hydrophilicity. Coating adhesion: Tested according to GB / T 9286-1998, using the cross-cut test, to evaluate the adhesion level between the hydrophilic coating and the surface of the floating body; Mechanical properties: Tensile strength is tested according to GB / T 1040.2-2006, and notched impact strength is tested according to GB / T 1043.1-2008; Long-term surface tension performance: The surface tension change rate was tested after the floating sample was immersed in distilled water at 25°C for 30 days.
[0028] Using unmodified HDPE floats as a blank control group, the performance indicators tested are shown in the table below. The test results show that the HDPE float material prepared using the method in this embodiment achieves a significant, precise, and long-lasting improvement in surface tension, substantial improvement in surface hydrophilicity, antistatic properties, and adhesion of functional coatings, while maintaining core mechanical properties without loss and even slightly improving them. It also exhibits excellent water resistance and stability, completely solving the technical pain points of existing HDPE floats, such as low surface tension, poor hydrophilicity, easy peeling of functional coatings, and lack of antistatic properties. This method is simple, environmentally friendly, cost-controllable, and suitable for industrial mass production. It can be widely applied to various HDPE float products, significantly improving the performance and application expansion capabilities of HDPE floats, and has extremely high industrial application value.
[0029] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and many other variations of different aspects of the invention as described above exist, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.
Claims
1. A modification method for increasing the surface tension of HDPE floating material, characterized in that, It includes the following steps: Step 1: Raw material pretreatment. Place 90.0-96.0% by weight of HDPE matrix resin in an oven to dry. Step 2, premixing: First, add the dried HDPE matrix resin, 0.5-1.5% by weight of anti-migration additive, and 0.5-1.5% by weight of compatibility additive into a high-speed mixer and mix to obtain the basic premix. Step 3: Mixing. Then, slowly add 1.5-4.0% by weight of acrylic acid, 0.3-1.0% by weight of benzoyl peroxide, 0.2-0.8% by weight of grafting accelerator, and 1.0-3.0% by weight of hydrophilic additives to a high-speed mixer and mix with the base premix to obtain the premix. Step 4, Low-temperature melt grafting: The premix is added to a twin-screw extruder. Through gentle melt shearing, benzoyl peroxide slowly decomposes to generate free radicals, which initiate a grafting reaction between acrylic acid and the HDPE matrix resin molecular chains. At the same time, hydrophilic additives, anti-migration additives, and compatibility additives are uniformly dispersed to form a modified HDPE melt. Step 5, Granulation: After the extruded strip is rapidly cooled and shaped in a cooling water tank, it is cut into modified HDPE granules with a particle size of 3-5mm by a pelletizer, and then placed in an oven to dry and remove moisture, thus obtaining modified HDPE float material.
2. The modification method for increasing the surface tension of HDPE float material according to claim 1, characterized in that, The oven temperature in step one is 80-90℃, and the drying time is 2-3 hours.
3. The modification method for increasing the surface tension of HDPE floating material according to claim 1, characterized in that, In step two, the high-speed mixer operates at a speed of 800-1000 r / min, a temperature of 50-60℃, and a mixing time of 5-8 minutes.
4. The modification method for increasing the surface tension of HDPE floating material according to claim 3, characterized in that, In step three, the high-speed mixer operates at a speed of 600-800 r / min, and the mixing time is 3-5 minutes.
5. The modification method for increasing the surface tension of HDPE float material according to claim 1, characterized in that, The temperatures of each section of the twin-screw extruder in step four are as follows: feeding section 130-140℃, melting section 145-155℃, grafting reaction section 155-165℃, homogenization section 150-160℃, and die head 145-155℃; screw speed 180-220 r / min, and vacuum degree -0.06~-0.08MPa.
6. The modification method for increasing the surface tension of HDPE floating material according to claim 1, characterized in that, In step five, the water temperature in the cooling water tank is 20-30℃, the oven temperature is 80℃, and the drying time is 2 hours.
7. The modification method for increasing the surface tension of HDPE float material according to claim 1, characterized in that, The mass percentage of HDPE matrix resin in step one is 92.0-94.5%; In step two, the mass percentage of the anti-migration agent is 0.8-1.2%, and the mass percentage of the compatibility agent is 0.8-1.2%. In step three, the mass percentage of acrylic acid is 2.0-3.0%, the mass percentage of benzoyl peroxide is 0.4-0.7%, the mass percentage of grafting accelerator is 0.3-0.5%, and the mass percentage of hydrophilic additive is 1.5-2.5%.
8. The modification method for increasing the surface tension of HDPE floating material according to claim 7, characterized in that, The anti-migration agent is polymethyl methacrylate; the compatibility agent is HDPE-g-AA with a grafting rate of 1.5-2.0%; the grafting accelerator is triethanolamine; and the hydrophilic agent is polyethylene glycol monomethyl ether acrylate.