A polyurethane adhesive and a method for preparing the same
By introducing macromolecular polyols and crosslinking agents into the prepolymer components and controlling the molar ratio to 8/1 to 12/1, the prepared polyurethane adhesive solves the problem of insufficient mechanical properties of low-hardness polyurethane adhesives, achieving high tensile strength and high elongation, and is suitable for bonding fiberglass materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIMING RES INST OF CHEM IND
- Filing Date
- 2023-10-07
- Publication Date
- 2026-07-24
AI Technical Summary
The existing low-hardness polyurethane adhesives have low mechanical properties, which limits their application range, and the use of plasticizers may lead to a decline in material performance and environmental pollution.
By introducing macromolecular polyols and crosslinking agents into the prepolymer components and controlling their molar ratio to be 8/1 to 12/1, the functionality of the polyurethane prepolymer is improved, and a polyurethane adhesive that does not require plasticizers is prepared.
While maintaining low hardness and high elongation, polyurethane adhesives have high tensile strength and bonding performance, making them suitable for bonding fiberglass materials.
Abstract
Description
Technical Field
[0001] This invention relates to the field of polyurethane adhesives, and in particular to a polyurethane adhesive with low hardness and high elongation and its preparation method. Background Technology
[0002] Polyurethane adhesives are adhesives whose molecular chains contain urethane or isocyanate groups. Polyurethane adhesives possess excellent bonding strength, low-temperature resistance, abrasion resistance, water resistance, oil resistance, solvent resistance, and chemical resistance, thus finding widespread application in civil engineering, transportation, electronic components, shoemaking, and packaging. By adjusting the ratio of soft to hard segments in the polyurethane adhesive molecular chain and designing the structure, adhesives with different hardness and elongation can be produced. However, some shortcomings have also been revealed in the use of polyurethane adhesives; for example, low-hardness polyurethane adhesives have relatively low mechanical properties, limiting their application. Therefore, it is necessary to develop low-hardness, high-elongation polyurethane adhesives to further expand the application range of polyurethane adhesives.
[0003] To reduce the hardness of polyurethane adhesives, plasticizers can be added to the formulation. Patent CN102516918B discloses a two-component polyurethane adhesive with high elongation. This adhesive uses a chain extender with internal plasticizing effect in combination with a polyol and a plasticizer, achieving an elongation at break greater than 1000% after curing. However, the material has low tensile strength (only 1.5 MPa), and the use of plasticizers in its formulation may lead to plasticizer precipitation in the later stages of material use, affecting material lifespan and causing environmental pollution.
[0004] Ye Shirong et al. (Ye Shirong, Peng Wei, Wang Gonghai, et al. Synthesis and properties of room temperature curing low hardness polyurethane elastomer. Polyurethane Industry, 2016, 31(4):4.DOI:10.3969 / j.issn.1005-1902.2016.04.013.) prepared a room temperature curing low hardness polyurethane elastomer that can be used as a mold adhesive using polyoxypropylene glycol, diisocyanate and trimethylolpropane as the main raw materials. However, the tensile strength of this material is only 3.5 MPa. In addition, plasticizers are also used in this formulation. Summary of the Invention
[0005] To address the problems existing in the prior art, this invention provides a polyurethane adhesive and its preparation method. The polyurethane adhesive incorporates a macromolecular polyol 1 and a crosslinking agent into the prepolymer component (component A), controlling the molar ratio of macromolecular polyol 1 to the crosslinking agent to be 8 / 1 to 12 / 1, thereby increasing the functionality of the polyurethane prepolymer and thus improving the matrix strength and adhesive performance of the polyurethane adhesive. This polyurethane adhesive formulation requires no plasticizers or other additives and contains no organic solvents, offering advantages of safety and environmental friendliness. Furthermore, the material is liquid at room temperature, facilitating easy handling and application. While maintaining low hardness and high elongation, the polyurethane adhesive also exhibits high tensile strength, making it suitable for bonding fiberglass materials.
[0006] The first aspect of this invention provides a polyurethane adhesive, comprising a prepolymer component (component A) and a chain extender component (component B).
[0007] Component A, by weight, comprises: 190 parts macromolecular polyol, 0.2-0.8 parts crosslinking agent, and 8-18 parts isocyanate;
[0008] Component B, by weight, includes: 20-50 parts of macromolecular polyol, 1-5 parts of chain extender, and 0.1-0.3 parts of catalyst.
[0009] The molar ratio of macromolecular polyol 1 to crosslinking agent in component A is 8 / 1 to 12 / 1.
[0010] The mass ratio of component A to component B is 100 / 20 to 50.
[0011] The macromolecular polyol 1 in component A is a polypropylene oxide diol with a number average molecular weight of 2000-4000 and a functionality of 2, preferably with a number average molecular weight of 4000.
[0012] The crosslinking agent in component A is one or more of trimethylolpropane, glycerol, trimethylolethane, and pentaerythritol, preferably trimethylolpropane.
[0013] The isocyanate in component A is one or more of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI), preferably toluene diisocyanate.
[0014] The macromolecular polyol 2 in component B is one or both of polypropylene oxide diol or polytetrahydrofuran diol with a number average molecular weight of 1000-2000 and a functionality of 2.
[0015] The chain extender in component B is one or more of diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA), 2,4-diamino-3,5-dimethylthiochlorobenzene (TX-2), and 1,4-butanediol (BDO), with dimethylthiotoluenediamine being preferred.
[0016] The catalyst in component B is one or more of organotin, organobismuth, and organomercury; organotin is preferably stannous octoate or dibutyltin dilaurate, organobismuth is preferably bismuth isooctanoate or bismuth carboxylate, and organomercury is preferably phenylmercuric acetate.
[0017] A second aspect of this invention provides a method for preparing a polyurethane adhesive, comprising the following steps:
[0018] (1) Preparation of component A:
[0019] Add macromolecular polyol 1, crosslinking agent, and isocyanate to the reactor and react at 70-85℃. After the NCO% reaches the theoretical value, cool down and discharge the material, then seal and store it.
[0020] (2) Preparation of component B:
[0021] Add macromolecular polyol 2, chain extender and catalyst to the reaction vessel, mix evenly, and then discharge and seal for storage.
[0022] Preferably, in step (1), the macromolecular polyol 1 and the crosslinking agent are dehydrated before use. Specifically, the dehydration operation is carried out at a temperature of 100℃~120℃ and a vacuum degree of -0.095MPa~-0.098MPa until the moisture content is ≤300ppm. The reaction time is preferably 1.5h~3h.
[0023] Preferably, in step (2), the macromolecular polyol 2 is dehydrated before use. The specific dehydration operation is as follows: under the conditions of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa, the water content is stirred and dehydrated until the water content is ≤300ppm. The mixing temperature is preferably 50℃~60℃.
[0024] Compared with existing technologies, this method introduces a high-functionality crosslinking agent into the prepolymer component (component A), and controls the molar ratio of macromolecular polyol 1 to the crosslinking agent to increase the functionality of the polyurethane prepolymer, thereby improving the matrix strength and adhesive properties of the polyurethane adhesive. The polyurethane adhesive of this invention has a hardness below 45A, a tensile strength above 9 MPa, an elongation of at least 850%, and a tensile shear strength greater than 2 MPa. The preferred hardness is 38–42A. Detailed Implementation
[0025] To better understand the content of this invention, the following description is provided in conjunction with specific embodiments, but the invention is not limited thereto. The term "parts" hereafter refers to quantities by weight.
[0026] Example 1
[0027] (1) Preparation of component A: In a three-necked flask, a mixture of poly(propylene oxide) glycol (90 parts) and trimethylolpropane (0.76 parts) with a number average molecular weight of 2000 was added at a molar ratio of 8 / 1. The mixture was stirred and mixed evenly. The mixture was dehydrated to a moisture content of ≤300ppm under the conditions of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa. Then the temperature was lowered to 50~60℃, and 15.2 parts of toluene diisocyanate were added. The reaction was carried out at atmospheric pressure for 1.5h~3h under the condition of 70~85℃. After the NCO% reached the theoretical value, the mixture was cooled, discharged, and sealed for storage.
[0028] (2) Preparation of component B: Add 20 parts of polypropylene glycol with a number average molecular weight of 1000 to a three-necked flask, stir continuously, and dehydrate until the moisture content is ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50℃~60℃, add 2.5 parts of DMTDA and 0.1 parts of dibutyltin dilaurate in sequence, stir continuously for 30min, and after the system materials are mixed evenly, discharge and seal for storage.
[0029] Mix components A and B at a mass ratio of 100 / 23 at room temperature, and after complete maturation at 100℃, conduct performance tests.
[0030] Example 2
[0031] (1) Preparation of component A: In a three-necked flask, a mixture of poly(propylene oxide) glycol (90 parts) and trimethylolpropane (0.27 parts) with a number average molecular weight of 4000 was added at a molar ratio of 10 / 1. The mixture was stirred and mixed evenly. The mixture was dehydrated to a moisture content of ≤300ppm under the conditions of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa. Then the temperature was lowered to 50~60℃, and 10.1 parts of toluene diisocyanate were added. The reaction was carried out at atmospheric pressure for 1.5h~3h under the condition of 70~85℃. After the NCO% reached the theoretical value, the mixture was cooled, discharged, and sealed for storage.
[0032] (2) Preparation of component B: Add 40 parts of polypropylene glycol with a number average molecular weight of 2000 to a three-necked flask, stir continuously, and dehydrate until the moisture content is ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50℃~60℃, add 4.5 parts of DMTDA and 0.1 parts of dibutyltin dilaurate in sequence, stir continuously for 30min, and after the system materials are mixed evenly, discharge and seal for storage.
[0033] Components A and B were mixed at a mass ratio of 100 / 44.5 at room temperature, and then fully cured at 100℃ before performance testing.
[0034] Example 3
[0035] (1) Preparation of component A: In a three-necked flask, a mixture of poly(propylene oxide) glycol (90 parts) and trimethylolpropane (0.23 parts) with a number average molecular weight of 4000 was added at a molar ratio of 12 / 1. The mixture was stirred and mixed evenly. The mixture was dehydrated to a moisture content of ≤300ppm under the conditions of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa. Then the temperature was lowered to 50~60℃, and 14 parts of diphenylmethane diisocyanate were added. The reaction was carried out at atmospheric pressure for 1.5h~3h under the condition of 70~85℃. After the NCO% reached the theoretical value, the mixture was cooled, discharged, and sealed for storage.
[0036] (2) Preparation of component B: Add 20 parts of polypropylene glycol with a number average molecular weight of 1000 to a three-necked flask, stir continuously, and dehydrate until the moisture content is ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50℃~60℃, add 1.1 parts of BDO and 0.1 parts of phenylmercuric acetate in sequence, stir continuously for 30min, and after the system materials are mixed evenly, discharge and seal for storage.
[0037] Components A and B were mixed at a mass ratio of 100 / 21 at room temperature, and then fully cured at 100℃ before performance testing.
[0038] Example 4
[0039] (1) Preparation of component A: Same as in Example 2.
[0040] (2) Preparation of component B: Add 10 parts of polypropylene oxide glycol with a number average molecular weight of 1000 and 10 parts of polytetrahydrofuran glycol with a number average molecular weight of 1000 to a three-necked flask, stir continuously to mix evenly, and stir to dehydrate until the moisture content is ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50℃~60℃, add 2.5 parts of DMTDA and 0.1 parts of dibutyltin dilaurate in sequence, stir continuously for 30min, and after the system materials are mixed evenly, discharge and seal for storage.
[0041] Components A and B were mixed at a mass ratio of 100 / 23 at room temperature, and then fully cured at 100℃ before performance testing.
[0042] Comparative Example 1
[0043] (1) Preparation of component A: Add 90 parts of polypropylene glycol with a number average molecular weight of 2000 to a three-necked flask, stir continuously, and dehydrate to a moisture content of ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50~60℃, add 13.6 parts of toluene diisocyanate, control the reaction temperature at 70~85℃, and react at normal pressure for 1.5h~3h. After NCO% reaches the theoretical value, cool down, discharge, and seal for storage.
[0044] (2) Preparation of component B: Same as in Example 1.
[0045] Components A and B were mixed at a mass ratio of 100 / 23 at room temperature, and then fully cured at 100℃ before performance testing.
[0046] Comparative Example 2
[0047] (1) Preparation of component A: Add 90 parts of polypropylene glycol with a number average molecular weight of 4000 to a three-necked flask, stir continuously, and dehydrate to a moisture content of ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50~60℃, add 10.1 parts of toluene diisocyanate, control the reaction temperature at 70~85℃, and react at atmospheric pressure for 1.5h~3h. After NCO% reaches the theoretical value, cool down, discharge, and seal for storage.
[0048] (2) Preparation of component B: Add 40 parts of polypropylene glycol with a number average molecular weight of 2000 and 0.27 parts of trimethylolpropane to a three-necked flask, stir and mix evenly, and stir and dehydrate until the moisture content is ≤300ppm under the conditions of temperature of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa; then cool down to 50℃~60℃, add 4.5 parts of DMTDA and 0.1 parts of dibutyltin dilaurate in sequence, and continue stirring for 30min. After the system materials are evenly mixed, discharge and seal for storage.
[0049] Components A and B were mixed at a mass ratio of 100 / 44.5 at room temperature, and then fully cured at 100℃ before performance testing.
[0050] Comparative Example 3
[0051] (1) Preparation of component A: In a three-necked flask, a mixture of polypropylene glycol (90 parts) and trimethylolpropane (0.50 parts) with a number average molecular weight of 4000 was added at a molar ratio of 6 / 1. The mixture was stirred and mixed evenly. The mixture was dehydrated to a moisture content of ≤300ppm under the conditions of a temperature of 100℃~120℃ and a vacuum degree of -0.095MPa~-0.098MPa. Then, the temperature was lowered to 50~60℃, and 10.5 parts of toluene diisocyanate were added. The reaction was carried out at atmospheric pressure for 1.5h~3h under the condition of a reaction temperature of 70~85℃. After the NCO% reached the theoretical value, the mixture was cooled, discharged, and sealed for storage.
[0052] (2) Preparation of component B: Same as in Example 1.
[0053] Components A and B were mixed at a mass ratio of 100 / 23 at room temperature, and then fully cured at 100℃ before performance testing.
[0054] Comparative Example 4
[0055] (1) Preparation of component A: In a three-necked flask, a mixture of poly(propylene oxide) glycol (90 parts) and trimethylolpropane (0.18 parts) with a number average molecular weight of 4000 was added at a molar ratio of 16 / 1. The mixture was stirred and mixed evenly. The mixture was dehydrated to a moisture content of ≤300ppm under the conditions of 100℃~120℃ and vacuum degree of -0.095MPa~-0.098MPa. Then the temperature was lowered to 50~60℃, and 10 parts of toluene diisocyanate were added. The reaction was carried out at atmospheric pressure for 1.5h~3h under the condition of 70~85℃. After the NCO% reached the theoretical value, the mixture was cooled, discharged, and sealed for storage.
[0056] (2) Preparation of component B: Same as in Example 1.
[0057] Components A and B were mixed at a mass ratio of 100 / 23 at room temperature, and then fully cured at 100℃ before performance testing.
[0058] The hardness of the materials was tested according to ISO 2039-2-2017; the tensile strength and elongation at break were tested according to GB / T528-2009; and the tensile shear strength of the adhesives was tested according to GB / T 33334-2016. The hardness, tensile strength, elongation at break, and other properties of the polyurethane elastomers prepared in Examples 1-4 and Comparative Examples 1-4 are shown in the table below:
[0059] Group Hardness / Shore A Tensile strength / MPa Elongation / % Tensile shear strength / MPa Example 1 42 9.82 1431 2.18 Example 2 38 9.10 1122 2.22 Example 3 38 9.45 1183 2.16 Example 4 42 10.22 850 2.32 Comparative Example 1 30 1.35 619 1.45 Comparative Example 2 30 3.78 1488 1.74 Comparative Example 3 41 5.01 993 1.89 Comparative Example 4 31 3.56 1362 1.56
[0060] The results from the examples and comparative examples above show that when the molar ratio of macromolecular polyol 1 to crosslinking agent is between 8 / 1 and 12 / 1, the prepared adhesive not only has high tensile strength but also high elongation at break. Furthermore, when used in the bonding experiment of fiberglass, the tensile shear strength of the material is >2 MPa. The experimental results from Example 1 and Comparative Example 1 show that the material performance is relatively low without the addition of a crosslinking agent. Examples 2 and Comparative Example 2 show that the material performance varies significantly after changing the process of adding the crosslinking agent. Comparative Examples 3 and 4 show that the material performance is relatively low when the molar ratio of macromolecular polyol 1 to crosslinking agent is greater than 12 / 1 or less than 8 / 1.
Claims
1. A polyurethane adhesive, comprising a prepolymer component A and a chain extender component B, Component A, by weight, comprises: Macromolecular polyol 1 90, crosslinking agent 0.2-0.8, isocyanate 8-18; Component B, by weight, comprises: 20-50 parts of macromolecular polyol, 1-5 parts of chain extender, and 0.1-0.3 parts of catalyst; The molar ratio of the macromolecular polyol 1 to the crosslinking agent is 8 / 1 to 12 / 1; The number-average molecular weight of the macromolecular polyol 1 is 2000-4000, and its functionality is 2. The macromolecular polyol 2 has a number average molecular weight of 1000-2000 and a functionality of 2. The mass ratio of component A to component B is 100 / 20 to 50.
2. The polyurethane adhesive according to claim 1, characterized in that, The macromolecular polyol 1 is polypropylene glycol.
3. The polyurethane adhesive according to claim 1, characterized in that, The crosslinking agent is one or more of trimethylolpropane, glycerol, trimethylolethane, and pentaerythritol.
4. The polyurethane adhesive according to claim 1, characterized in that, The isocyanate is one or more of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI).
5. The polyurethane adhesive according to claim 1, characterized in that, The macromolecular polyol 2 is one or both of polypropylene oxide diol or polytetrahydrofuran diol.
6. The polyurethane adhesive according to claim 1, characterized in that, The chain extender is one or more of diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA), 2,4-diamino-3,5-dimethylthiochlorobenzene (TX-2), and 1,4-butanediol (BDO).
7. The polyurethane adhesive according to claim 1, characterized in that, The catalyst is one or more of organotin, organobismuth, and organomercury.
8. The polyurethane adhesive according to claim 7, characterized in that, The organotin is stannous octoate or dibutyltin dilaurate, the organobismuth is bismuth isooctanoate or bismuth carboxylate, and the organomercury is phenylmercuric acetate.
9. A method for preparing the polyurethane adhesive according to any one of claims 1-8, comprising the following steps: (1) Preparation of component A: Add macromolecular polyol 1, crosslinking agent and isocyanate to the reaction vessel, react at 70-85℃, and after NCO% reaches the theoretical value, cool down and discharge the material, and seal it for storage. (2) Preparation of component B: Add macromolecular polyol 2, chain extender and catalyst to the reaction vessel, mix evenly, and then discharge and seal for storage.