One-component polyurethane adhesive for bonding rubber and plastic foam materials and its preparation method; rubber and plastic foam shock-absorbing and sound-insulating pads and their preparation methods.

Abstract

This invention relates to the field of building materials technology, specifically to a one-component polyurethane adhesive for bonding rubber and plastic foam materials and its preparation method, as well as a rubber and plastic foam vibration damping and sound insulation pad and its preparation method. The raw material components of the one-component polyurethane adhesive include: polyether polyol, hydroxyl-terminated polysiloxane, isocyanate, sulfide, stabilizer, plasticizer, and antioxidant; wherein the stabilizer includes steric hindrance-resistant hydrolysis stabilizer and reactive stabilizer. The one-component polyurethane adhesive of this invention enables the rubber and plastic foam vibration damping and sound insulation pad to have excellent damping performance and sound insulation effect, as well as excellent creep resistance and resilience, significantly increasing the added value of recycled materials.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a single-component polyurethane adhesive for bonding rubber and plastic foam materials and its preparation method, and a rubber and plastic foam shock-absorbing and sound-insulating pad and its preparation method. Background Technology

[0002] How to handle the large amounts of solid waste generated from the construction and industrial sectors? For example, the rubber-plastic (NBR / PVC) insulation pipes widely used in air conditioning systems, commonly known as rubber-plastic foam, have a service life of decades due to their excellent insulation, flexibility, and aging resistance. However, after reaching their service life, these discarded insulation pipes are bulky, chemically stable, and difficult to degrade naturally. Traditional landfill or incineration methods not only occupy land resources but also pose risks of soil and air pollution and the release of toxic gases. Crushing and re-bonding waste rubber-plastic materials is one of the most promising technological pathways to transform them from "waste" into "recycled resources." Furthermore, with the development of the construction industry, noise and vibration interference during building operation has become a core issue affecting human comfort and health. Traditional solutions often involve adding elastic padding layers (such as foam plastics or rubber pads) to the floor structure to block sound bridges and vibration transmission. However, these padding materials are mostly derived from single-use energy sources, and their entire life cycle—from production and use to disposal—presents both resource consumption and environmental pollution pressures. Utilizing the large amounts of solid waste generated in the construction and industrial sectors to produce vibration-damping and sound-insulating rubber and plastic foam pads for building applications not only disposes of solid waste but also produces recycled products with practical value, aligning with the core concept of a circular economy. However, the technological realization of this approach faces multiple challenges in materials science and engineering, with the core bottleneck lying in the adhesive used for bonding. Summary of the Invention

[0003] To facilitate a clearer understanding of the technical solutions and effects of this invention, the following detailed description, in conjunction with specific embodiments, is provided. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the definitions in this specification shall prevail.

[0004] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0005] In a first aspect, the present invention provides a single-component polyurethane adhesive for bonding rubber and plastic foam materials, wherein the raw material components include: polyether polyol, hydroxyl-terminated polysiloxane, isocyanate, sulfide, stabilizer, plasticizer, and antioxidant; wherein the stabilizer includes sterically hindered hydrolysis-resistant stabilizer and reactive stabilizer.

[0006] In this invention, the synergistic effect of reactive stabilizers and sterically hindered hydrolysis stabilizers avoids the gelation risk of traditional urethane adhesives (especially amine-containing systems), while simultaneously resolving storage stratification defects caused by insufficient compatibility between hydroxyl-terminated polysiloxanes and polyether polyols, and effectively inhibiting the degradation of sulfide dynamic bonds under humid and hot environments. Furthermore, the reaction rate between the hydroxyl groups of the hydroxyl-terminated polysiloxane and isocyanates is moderate and stable, allowing for precise control of the prepolymer synthesis process and obtaining polymers with uniform molecular weight distribution. At the same time, the polysiloxane segments possess extremely low surface energy and excellent flexibility, significantly reducing the adhesive's surface tension, enhancing the wetting and adhesion of rubber and plastic foam particles, and imparting excellent resilience and resistance to compression set to the cured products.

[0007] As a preferred technical solution of the present invention, the raw material components of the single-component polyurethane adhesive, by weight, include: 100 parts of polyether polyol, 5-20 parts of hydroxyl-terminated polysiloxane, 65-75 parts of isocyanate, 3-12 parts of sulfide, 0.1-2 parts of stabilizer, 5-35 parts of plasticizer, and 0.1-3 parts of antioxidant.

[0008] As a preferred technical solution of the present invention, the raw material components of the single-component polyurethane adhesive, by weight, include: 100 parts of polyether polyol, 8-15 parts of hydroxyl-terminated polysiloxane, 68-72 parts of isocyanate, 5-10 parts of sulfide, 0.5-1.5 parts of stabilizer, 10-20 parts of plasticizer, and 0.5-1.5 parts of antioxidant.

[0009] In this invention, controlling the various raw material components can better achieve the effects of high sound insulation, high damping, high resilience, and long-term stability.

[0010] The polyether polyols used in this invention can be selected from those commonly found in the art. As a preferred embodiment of this invention, the polyether polyol is selected from at least one of polyether polyol 230, polyether polyol 3050, and polyether polyol 330N, preferably polyether polyol 230. The molecular structure of polyether polyol 230 is adapted to the adhesive properties of rubber and plastic foam, thereby improving the wettability and adhesive strength between the adhesive and the foam particles.

[0011] As a preferred embodiment of the present invention, the hydroxyl-terminated polysiloxane comprises a hydroxyl-terminated polyether-modified silicone oil. This is commercially available, including but not limited to Dow Corning SF-8427 hydroxyl-terminated polyether-modified silicone oil.

[0012] In this invention, the dual-hydroxyl-terminated polyether modified silicone oil contains polyether segments at both ends of its molecular chain, which improves its compatibility with the polyether polyol system, thereby further reducing the risk of storage stratification caused by polarity differences. At the same time, it retains the low surface tension and ultra-flexible properties of the siloxane backbone, making it more efficient at wetting rubber and plastic foams and stronger in terms of resilience and resistance to compression set after curing. In addition, the presence of polyether segments can form a more uniform interpenetrating structure with the sulfide dynamic network, further improving energy dissipation efficiency. This results in the adhesive maintaining excellent stability while achieving a higher weighted impact sound reduction and lower compression set in the product.

[0013] The isocyanate used in this invention can be selected from those commonly found in the art. As a preferred technical solution of this invention, the isocyanate is selected from aromatic polyisocyanates. Examples of aromatic polyisocyanates include at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, liquefied MDI, terephthalic dimethyl diisocyanate (PPDI), and naphthalene 1,5-diisocyanate (NDI). It is preferably diphenylmethane diisocyanate (MDI), specifically MDI-50. MDI-50 has moderate reactivity and can form stable polyurethane molecular chains with polyether polyols and polyether amines, while also synergistically constructing a crosslinking network with sulfides.

[0014] As a preferred embodiment of the present invention, the sulfide is selected from aliphatic dihydroxy compounds containing disulfide bonds and / or aromatic dihydroxy compounds containing thioether bonds.

[0015] As a preferred embodiment of the present invention, the sulfide is selected from aliphatic dihydroxy compounds containing disulfide bonds and aromatic dihydroxy compounds containing thioether bonds.

[0016] As a preferred embodiment of the present invention, the weight ratio of the aliphatic dihydroxy compound containing disulfide bonds to the aromatic dihydroxy compound containing thioether bonds is 1:(0.5-3), for example, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.5 or 1:3, preferably 1:(0.8-1.5).

[0017] In this invention, further research revealed that controlling the sulfide to be a combination of aliphatic dihydroxy compounds containing disulfide bonds (such as 2-hydroxyethyl disulfide) and aromatic dihydroxy compounds containing sulfide bonds (such as 4,4'-dihydroxydiphenyl sulfide), and controlling the weight ratio of the two to be 1:(0.5-3), particularly 1:(0.8-1.5), enables the finally cured rubber-plastic foam damping and sound insulation pad to have better damping sound insulation and creep resistance. The likely reason is that the aforementioned sulfides can construct a dynamic cross-linked network of "rigidity and flexibility" within the system. The flexible disulfide bonds provide reversible breakage and recombination capabilities, efficiently dissipating impact vibration energy, while the rigid sulfide bond aromatic ring structure enhances the network's strength and heat resistance. This combination provides excellent performance balance and process tolerance, thereby endowing the glue-cured product with optimal overall damping sound insulation and creep resistance.

[0018] As a preferred embodiment of the present invention, the aliphatic dihydroxy compound containing disulfide bonds is selected from 2-hydroxyethyl disulfide and / or 2-hydroxypropyl disulfide, preferably 2-hydroxyethyl disulfide.

[0019] As a preferred embodiment of the present invention, the aromatic dihydroxy compound containing a thioether bond is selected from at least one of 4,4'-dihydroxydiphenyl sulfide, bis(2-hydroxyphenyl) sulfide and bis(2-thienyl) sulfide, preferably 4,4'-dihydroxydiphenyl sulfide.

[0020] As a preferred embodiment of the present invention, the weight ratio of the steric hindrance anti-hydrolysis stabilizer to the reactive stabilizer is (5-20):1, for example, 5:1, 8:1, 10:1, 12:1, 15:1 or 20:1, preferably (8-13):1.

[0021] As a preferred embodiment of the present invention, the steric hindrance hydrolysis stabilizer includes polymeric carbodiimide (such as Stabaxol P200).

[0022] As a preferred embodiment of the present invention, the reactive stabilizer is selected from at least one of benzoyl chloride, phosphoric acid, sulfuric acid and anhydrous hydrogen chloride, preferably phosphoric acid.

[0023] The plasticizer in this invention can effectively reduce the inter-chain forces of polymers, thereby significantly improving the wettability of the adhesive to the rubber and plastic foam particles, and can increase the toughness and resilience of the product to a certain extent.

[0024] As a preferred embodiment of the present invention, the plasticizer is selected from at least one of chlorinated fatty acid esters, phosphate esters, phthalates and trimellitates, preferably chlorinated fatty acid esters, specifically chlorinated palm oil methyl ester.

[0025] The antioxidants used in this invention can be any type in the art, including but not limited to antioxidant 1010, antioxidant 1076, or antioxidant 1024.

[0026] In this invention, the weight ratio of sterically hindered hydrolysis stabilizer to reactive stabilizer is controlled within a specific range. The reactive stabilizer (such as phosphoric acid) can effectively suppress the side reactions between hydroxyl-terminated polysiloxane and isocyanate during the prepolymer synthesis stage, ensuring that the hydroxyl-terminated polysiloxane can effectively enhance wettability and resilience. At the same time, an appropriate amount of sterically hindered hydrolysis stabilizer can effectively capture the acidic byproducts generated by the degradation of sulfide dynamic bonds during storage, successfully solving the defect of insufficient long-term humid heat stability. Moreover, because its dosage is controlled within a reasonable range, it can avoid excessive stabilization from inhibiting the dynamic cross-linking network, thus not weakening the wettability and resilience effect.

[0027] In a second aspect, the present invention provides a method for preparing a one-component polyurethane adhesive for bonding rubber and plastic foam materials as described in the first aspect of the present invention, the preparation method comprising: (1) Add polyether polyol, plasticizer, antioxidant and hydroxyl-terminated polysiloxane to the reactor and mix for the first time to obtain the first mixture; (2) Add sulfide to the first mixture to perform a second mixing, thereby obtaining a second mixture; (3) Add a reactive stabilizer to the second mixture to perform a third mixing, and obtain a third mixture; (4) Add isocyanate to the third mixture and perform a fourth mixture to obtain the prepolymer; (5) Degas the prepolymer, then add a steric hindrance hydrolysis stabilizer for the fifth mixing, and then cure it to obtain a one-component polyurethane adhesive.

[0028] The preparation method of the present invention has controllable process parameters, is easy to operate, and is suitable for industrial production. The prepared adhesive is gel-free, has good storage stability, and has excellent bonding performance to rubber and plastic foam materials.

[0029] There are no special restrictions on the first mixing in step (1) of this invention, as long as the components can be mixed evenly. In order to avoid the influence of moisture in the raw materials on the reaction, the polyether polyol and plasticizer are generally dried and then mixed with antioxidant and hydroxyl-terminated polysiloxane to obtain the first mixture. Specifically, in step (1), the polyether polyol and plasticizer are added to the reaction vessel, heated to 100-130°C, and high vacuum is turned on (vacuum degree not less than 0.098MPa) for 2-4 hours to dehydrate. The moisture content is detected to be ≤0.03%. Then, the temperature is lowered to 50-65°C and the antioxidant and hydroxyl-terminated polysiloxane are added and mixed for 20-60 minutes to obtain the first mixture. As a preferred technical solution of the present invention, in step (2), the conditions for the second mixing include: a temperature of 45-50°C and a time of 30-60 minutes.

[0030] Specifically, in step (2), sulfides are added to the first mixture and mixed at 45-55°C for 30-60 minutes to obtain the second mixture.

[0031] In step (3), the reactive stabilizer is preferably added to the second mixture by dripping, and the reactive stabilizer is preferably added in 20-40 minutes. As a preferred technical solution of the present invention, the conditions for the third mixture include: temperature of 45-55℃ and time of 1-2 hours.

[0032] Specifically, in step (3), a reactive stabilizer is added dropwise to the second mixture at 45-55°C, and the addition of the reactive stabilizer is completed in 20-30 minutes. Then, the third mixing is carried out at 45-55°C for 1-2 hours to obtain the third mixture.

[0033] As a preferred technical solution of the present invention, in step (4), the isocyanate is added dropwise into the third mixture. Preferably, the temperature during the dropwise addition is 35-45°C, and preferably, the isocyanate is added completely within 1-1.5 hours. More preferably, after the isocyanate is added completely, the mixture is reacted at 82-88°C for 2-4 hours.

[0034] Specifically, in step (4), the third mixture is cooled to 35-45°C, and isocyanate is slowly added dropwise under stirring, with the addition time controlled at 1-1.5 hours. After the addition is complete, the temperature is raised to 82-88°C and reacted for 2-4 hours to obtain the prepolymer.

[0035] As a preferred technical solution of the present invention, in step (5), the degassing method includes: degassing for 30-50 minutes under the conditions of 82-88℃ and -0.09~-0.075MPa.

[0036] In step (5), there are no special restrictions on the conditions of the fifth mixing, as long as the mixture can be mixed evenly. It is preferred to mix under nitrogen protection at 30-40°C for 20-30 minutes.

[0037] As a preferred technical solution of the present invention, in step (5), the curing conditions include: being carried out under nitrogen protection, at room temperature, for 0.5-1.5 hours.

[0038] Specifically, in step (5), the prepolymer is degassed for 30-50 minutes at 82-88℃ and -0.09~-0.075MPa, cooled to 30-40℃, and under nitrogen protection, a steric hindrance-resistant hydrolysis stabilizer is added, stirred and mixed for 20-30 minutes, and then cured at room temperature for 0.5-1.5 hours to obtain a one-component polyurethane adhesive.

[0039] Thirdly, the present invention provides a method for preparing a rubber and plastic foam vibration damping and sound insulation pad, the method comprising: crushing recycled rubber and plastic foam into granules, and then mixing, molding, curing, opening a mold, and maturing the granules with a single-component polyurethane adhesive to obtain a rubber and plastic foam vibration damping and sound insulation pad; wherein the single-component polyurethane adhesive is the single-component polyurethane adhesive described in the first aspect of the present invention or the single-component polyurethane adhesive prepared by the preparation method described in the second aspect of the present invention.

[0040] As a preferred embodiment of the present invention, the particle size is 1-3 mm.

[0041] As a preferred embodiment of the present invention, the stirring time is 5-10 minutes.

[0042] As a preferred embodiment of the present invention, the mass of the single-component polyurethane adhesive is 5%-12% of the mass of the particles.

[0043] As a preferred technical solution of the present invention, the molding conditions include: molding and curing under steam at 110°C for 40-50 minutes.

[0044] As a preferred technical solution of the present invention, the curing conditions include: standing at room temperature for 30-50 hours.

[0045] Fourthly, the present invention provides a rubber and plastic foam shock-absorbing and sound-insulating pad, which is prepared by the method for preparing the rubber and plastic foam shock-absorbing and sound-insulating pad described in the third aspect of the present invention.

[0046] Compared with the prior art, the present invention has at least the following beneficial effects: The single-component polyurethane adhesive in this invention enables rubber and plastic foam shock-absorbing and sound-insulating pads to have excellent damping performance and sound insulation effect, as well as excellent creep resistance and resilience, which greatly improves the added value of recycled materials. Detailed Implementation

[0047] The present invention will now be described in detail through embodiments: In the following embodiments, unless otherwise specified, the amount of raw materials added refers to parts by weight.

[0048] Example 1 Preparation of one-component polyurethane adhesive: (1) Add 100 parts of polyether polyol 230 and 15 parts of chloropalmitoyl methyl ester to the reactor, heat to 110±2℃, turn on high vacuum (vacuum degree not less than 0.098MPa), dehydrate for 2.5 hours until the moisture content is ≤0.03%, then cool down to 60℃ and add 0.8 parts of antioxidant 1010 and 10 parts of Dow Corning SF-8427 double-hydroxyl-terminated polyether modified silicone oil and mix for 30 minutes to obtain the first mixture; (2) Cool down to 50°C, add 3 parts of 2-hydroxyethyl disulfide and 3 parts of 4,4'-dihydroxydiphenyl sulfide, and stir for 30 minutes; (3) Keep at 50±2℃, add 0.06 parts of phosphoric acid (mass concentration of 85%) dropwise over 30 minutes, stir at 50±2℃ for 1 hour to obtain the third mixture; (4) Cool down to 40±2℃, slowly add 70 parts of MDI-50 dropwise while stirring, and add it over 1.5 hours. Then heat up to 85±2℃ and react for 3.5 hours to obtain the prepolymer. (5) Keep the temperature at 85±2℃ and degas the prepolymer at -0.08MPa for 40 minutes. Cool the temperature to 35±2℃ and add 0.5 parts of polymeric carbodiimide (Stabaxol P200) under nitrogen protection. Stir for 20 minutes and cure at room temperature for 1 hour. Discharge the material to obtain a single-component polyurethane adhesive.

[0049] Example 2 The method is the same as in Example 1, except that the amount of Dow Corning SF-8427 hydroxyl-terminated polyether modified silicone oil is 12 parts, the amount of 2-hydroxyethyl disulfide is 2 parts, the amount of 4,4'-dihydroxydiphenyl sulfide is 5 parts, the amount of polymeric carbodiimide (Stabaxol P200) is 0.6 parts, the amount of MDI-50 is 72 parts, the amount of phosphoric acid is 0.05 parts, the amount of chloropalmitoyl palmitate is 18 parts, and the amount of antioxidant 1010 is 1 part.

[0050] The rest is the same as in Example 1.

[0051] Example 3 The method is the same as in Example 1, except that the amount of Dow Corning SF-8427 hydroxyl-terminated polyether modified silicone oil used is 25 parts.

[0052] Example 4 The method is the same as in Example 1, except that the amount of 4,4'-dihydroxydiphenyl sulfide is 6 parts and no 2-hydroxyethyl disulfide is added.

[0053] Example 5 The method is the same as in Example 1, except that the amount of 2-hydroxyethyl disulfide is 6 parts and 4,4'-dihydroxydiphenyl sulfide is not added.

[0054] Example 6 The method is the same as in Example 1, except that the amount of polymeric carbodiimide used is 2 parts.

[0055] Comparative Example 1 The method of Example 1 differs in that there is no step (2), and steps (3)-(5) are performed directly after step (1) is completed.

[0056] Performance testing Preparation of rubber and plastic foam shock-absorbing and sound-insulating pads: The recycled rubber and plastic foam is crushed into 1-3mm particles and fed into a mixing tank. Then, while stirring, a single-component polyurethane adhesive is sprayed in at a rate of 8% of the particle mass. After mixing evenly, the mixture is molded and cured under 110℃ steam for 45 minutes. After demolding and standing at room temperature for 48 hours, it can be sliced ​​and cut into 5mm thick, 100cm wide, and 100cm long sheets to be used as rubber and plastic foam shock-absorbing and sound-insulating pads.

[0057] 1. Sound insulation performance test: The test shall be conducted in accordance with GB / T 19889.6-2005 "Acoustic Buildings and Building Components Sound Insulation Measurement Part 6: Laboratory Measurement of Impact Sound Insulation of Floor Slabs" and GB50121-2005 "Standard for Evaluation of Building Sound Insulation".

[0058] 2. Loss factor test: Refer to standard GB / T 16406-1996, the test temperature is 20℃.

[0059] 3. Compression set test, referring to standard GB / T 7759, test condition is 70℃. 22h compression 30%.

[0060] The test results are shown in Table 1.

[0061] Table 1 Performance Test Results

[0062] The recycled rubber and plastic foam products prepared using the single-component polyurethane adhesive of the present invention exhibit excellent performance in impact sound insulation, material damping characteristics, and creep resistance.

Claims

1. A one-component polyurethane adhesive for bonding rubber and plastic foam materials, characterized in that, The raw material components include: polyether polyol, hydroxyl-terminated polysiloxane, isocyanate, sulfide, stabilizer, plasticizer, and antioxidant; wherein the stabilizer includes sterically hindered hydrolysis stabilizer and reactive stabilizer.

2. The single-component polyurethane adhesive according to claim 1, characterized in that, By weight, the raw material components of the single-component polyurethane adhesive include: 100 parts of polyether polyol, 5-20 parts of hydroxyl-terminated polysiloxane, 65-75 parts of isocyanate, 3-12 parts of sulfide, 0.1-2 parts of stabilizer, 5-35 parts of plasticizer, and 0.1-3 parts of antioxidant.

3. The single-component polyurethane adhesive according to claim 1 or 2, characterized in that, The polyether polyol is selected from at least one of polyether polyol 230, polyether polyol 3050 and polyether polyol 330N.

4. The single-component polyurethane adhesive according to claim 1 or 2, characterized in that, The hydroxyl-terminated polysiloxane includes a bihydroxyl-terminated polyether modified silicone oil; the isocyanate is selected from aromatic polyisocyanates.

5. The one-component polyurethane adhesive according to claim 1 or 2, characterized in that, The sulfide is selected from aliphatic dihydroxy compounds containing disulfide bonds and / or aromatic dihydroxy compounds containing thioether bonds.

6. The one-component polyurethane adhesive according to claim 5, characterized in that, The aliphatic dihydroxy compound containing a disulfide bond is selected from 2-hydroxyethyl disulfide and / or 2-hydroxypropyl disulfide; the aromatic dihydroxy compound containing a thioether bond is selected from at least one of 4,4'-dihydroxydiphenyl sulfide, bis(2-hydroxyphenyl) sulfide and bis(2-thienyl) sulfide, preferably 4,4'-dihydroxydiphenyl sulfide.

7. The one-component polyurethane adhesive according to claim 1 or 2, characterized in that, The weight ratio of the sterically hindered hydrolysis stabilizer to the reactive stabilizer is (5-20):

1.

8. A method for preparing a one-component polyurethane adhesive for bonding rubber and plastic foam materials as described in any one of claims 1-7, characterized in that, The preparation method includes: (1) Add polyether polyol, plasticizer, antioxidant and hydroxyl-terminated polysiloxane to the reactor and mix for the first time to obtain the first mixture; (2) Add sulfide to the first mixture to perform a second mixing, thereby obtaining a second mixture; (3) Add a reactive stabilizer to the second mixture to perform a third mixing, and obtain a third mixture; (4) Add isocyanate to the third mixture and perform a fourth mixture to obtain the prepolymer; (5) Degas the prepolymer, then add a steric hindrance hydrolysis stabilizer for the fifth mixing, and then cure it to obtain a one-component polyurethane adhesive.

9. A method for preparing a rubber and plastic foam shock-absorbing and sound-insulating pad, characterized in that, The preparation method includes: crushing recycled rubber and plastic foam into granules, then mixing, molding, curing, opening the mold, and maturing the granules with a single-component polyurethane adhesive to obtain a rubber and plastic foam shock-absorbing and sound-insulating pad; wherein the single-component polyurethane adhesive is the single-component polyurethane adhesive according to any one of claims 1-7, or the single-component polyurethane adhesive prepared by the preparation method of claim 8.

10. A rubber and plastic foam shock-absorbing and sound-insulating pad, characterized in that, It is prepared by the method of preparing rubber and plastic foam shock-absorbing and sound-insulating pad as described in claim 9.

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