A PUR adhesive for textiles, its preparation method and application

Abstract

This invention belongs to the field of adhesive technology, and relates to a PUR adhesive for textiles, its preparation method, and its application. The preparation method includes first melt-blending polyol and TPU, then reacting the resulting mixture with isocyanate to prepare a polyurethane prepolymer, then grafting the obtained polyurethane prepolymer with acrylic monomers, and finally adding phosphoric acid to adjust the stability of the system. By strictly controlling the order of feeding, placing the acrylic monomers after prepolymerization and then carrying out the grafting reaction, and adding phosphoric acid in the last step, the occurrence of side reactions is greatly reduced, the dispersion uniformity of TPU and the reaction stability are improved, and the problems of rapid polymerization and gelation caused by premature addition of phosphoric acid as a catalyst are effectively avoided, making the reaction more controllable. The resulting PUR adhesive has the characteristics of stable viscosity, good compatibility, high peel strength, and excellent water resistance, and is suitable for textile fabric lamination and bonding.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, and relates to a PUR adhesive for textiles, its preparation method, and its application. Background Technology

[0002] PUR (Polyurethane Reactive Hot Melt Adhesive) combines the immediate initial tack of hot melt adhesives with the high strength and excellent high-temperature resistance of chemically reactive adhesives. It is widely used in many industrial fields such as textiles, furniture, automobiles, and packaging, and plays a core role, especially in the production of textile composite materials and high-performance functional fabrics.

[0003] Textile PUR adhesives are often prepared by compounding polyols, acrylic monomers, TPU, phosphoric acid, etc. Traditional processes often involve adding the components all at once or arbitrarily, which has the following drawbacks: ① Premature addition of phosphoric acid can violently catalyze the NCO / OH reaction, making the reaction prone to explosive polymerization, resulting in a sudden increase in product viscosity and gel failure; ② Acrylic monomers and isocyanates directly contact each other and compete for a reaction, leading to a decrease in the molecular weight of the main chain of the resulting adhesive and affecting the bonding strength; ③ Uneven dispersion of TPU can easily lead to agglomeration and delamination, resulting in a decrease in the water resistance and flexibility of the adhesive layer; ④ Poor reaction controllability and low batch stability make it difficult to meet the high-end requirements of textile composites.

[0004] Therefore, in response to the above-mentioned technical problems, there is an urgent need to develop a method for preparing PUR adhesives for textiles that has a reasonable feeding sequence, stable reaction, and few side reactions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a PUR adhesive for textiles, its preparation method, and its application. The preparation method significantly reduces side reactions by strictly controlling the order of material addition, making the reaction stable and controllable, and improving the compatibility of various materials. As a result, the final PUR adhesive for textiles is gel-free, has uniform viscosity, and possesses excellent bonding performance and water and aging resistance.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a PUR adhesive for textiles, the method comprising the following steps: (1) Polyol and TPU are melt-blended to obtain a mixture; (2) React the mixture obtained in step (1) with isocyanate to obtain a polyurethane prepolymer; (3) React the polyurethane prepolymer obtained in step (2) with acrylic monomers to obtain acrylic grafted polyurethane prepolymer; (4) The acrylic-grafted polyurethane prepolymer obtained in step (3) is mixed with phosphoric acid to obtain the PUR adhesive for textiles.

[0007] The preparation method of the textile PUR adhesive provided by this invention does not require changing the main formulation. By strictly controlling the order of feeding materials, polyol and TPU are first melt-blended, and then the resulting mixture is reacted with isocyanate to prepare a polyurethane prepolymer. Next, acrylic monomers are used to graft the obtained polyurethane prepolymer, and finally phosphoric acid is added to adjust the stability of the system. By placing the acrylic monomers after the prepolymerization and then performing the grafting reaction with the polyurethane prepolymer, and adding phosphoric acid to the system in the last step, the competitive reaction between acrylic monomers and isocyanate can be effectively reduced, the probability of side reactions can be significantly reduced, the dispersion uniformity of TPU and the reaction stability can be improved, and the problems of rapid polymerization and gelation caused by premature addition of phosphoric acid can also be effectively avoided, making the reaction more controllable. As a result, the PUR adhesive can be guaranteed to have stable viscosity, good compatibility, high peel strength, and excellent water and aging resistance, and is suitable for textile fabric lamination and bonding.

[0008] Preferably, the raw material of the textile PUR adhesive comprises the following components in parts by weight: 40-60 parts by weight of polyol; 10-25 parts by weight of TPU; 10-20 parts by weight of isocyanate; 5-15 parts by weight of acrylic monomers; Phosphoric acid 0.05~0.3 parts by weight.

[0009] The amount of the polyol used can be 40 parts by weight, 42 parts by weight, 44 parts by weight, 46 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 56 parts by weight, 58 parts by weight, or 60 parts by weight, etc.

[0010] The amount of TPU used can be 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 24 parts by weight, or 25 parts by weight, etc.

[0011] The amount of isocyanate used can be 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, or 20 parts by weight, etc.

[0012] The amount of the acrylic monomer can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, or 15 parts by weight.

[0013] The amount of phosphoric acid used can be 0.05 parts by weight, 0.1 parts by weight, 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, or 0.3 parts by weight, etc.

[0014] Preferably, the polyol comprises a polyester polyol.

[0015] In this invention, the polyester polyol includes, but is not limited to, adipic acid-based polyester polyols.

[0016] Preferably, before the melt blending in step (1), the polyol is further subjected to dehydration treatment at a vacuum of 115~125℃ (e.g., 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, 121℃, 122℃, 123℃, 124℃ or 125℃, etc.) and above -0.095 MPa (e.g., -0.095 MPa, -0.096 MPa, -0.097 MPa, -0.098 MPa or -0.099 MPa, etc.) for 1.5~2.5 h (e.g., 1.5 h, 1.7 h, 1.9 h, 2.1 h, 2.3 h or 2.5 h, etc.) to obtain the dehydrated polyol; Preferably, the water content in the dehydrated polyol is ≤0.03% by mass, for example, 0.028%, 0.026%, 0.024%, 0.022%, 0.02%, 0.018%, 0.016%, 0.014%, 0.01%, or 0.08%.

[0017] Preferably, the melting and blending temperature in step (1) is 115~125℃, for example, 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, 121℃, 122℃, 123℃, 124℃ or 125℃.

[0018] Preferably, the melt blending time in step (1) is 30 to 40 minutes, such as 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, or 40 minutes.

[0019] Preferably, the isocyanate includes an aromatic isocyanate.

[0020] In this invention, the aromatic isocyanates include, but are not limited to, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), etc.

[0021] Preferably, the reaction temperature in step (2) is 75~90℃, for example 75℃, 77℃, 79℃, 81℃, 83℃, 85℃, 87℃, 89℃ or 90℃.

[0022] Preferably, the reaction time in step (2) is 2 to 3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours.

[0023] Preferably, the acrylic monomer includes hydroxyacrylic monomers.

[0024] Preferably, the hydroxyacrylate monomer includes hydroxyethyl methacrylate.

[0025] Preferably, the reaction temperature in step (3) is 55~60℃, such as 55℃, 55.5℃, 56℃, 56.5℃, 57℃, 57.5℃, 58℃, 58.5℃, 59℃, 59.5℃ or 60℃.

[0026] Preferably, the reaction time in step (3) is 1 to 2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours.

[0027] Preferably, the mixing temperature in step (4) is 20~45℃, such as 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃ or 45℃, etc.

[0028] Preferably, the mixing time in step (4) is 20 to 30 minutes, such as 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, or 30 minutes.

[0029] Preferably, after the mixing in step (4) is completed, a vacuum degassing step is also included.

[0030] As a preferred embodiment of the present invention, the preparation method of the PUR adhesive for textiles includes the following steps: (1) The polyol is dehydrated at 115~125℃ and vacuum degree above -0.095 MPa for 1.5~2.5 h to obtain dehydrated polyol with a water mass percentage of ≤0.03%. Then the obtained dehydrated polyol and TPU are mixed at 115~125℃ for 30~40 min until completely melted and uniform to obtain a mixture. (2) React the mixture obtained in step (1) and isocyanate at 75~90℃ for 2~3 h to obtain polyurethane prepolymer; (3) The polyurethane prepolymer obtained in step (2) and the acrylic monomer are subjected to a grafting reaction at 55~60℃ for 1~2h to obtain acrylic grafted polyurethane prepolymer. (4) The acrylic-grafted polyurethane prepolymer obtained in step (3) and phosphoric acid are mixed at 20~45°C for 20~30 min, and then degassed under vacuum to obtain the PUR adhesive for textiles.

[0031] In a second aspect, the present invention provides a PUR adhesive for textiles, wherein the PUR adhesive for textiles is prepared by the preparation method described in the first aspect.

[0032] Thirdly, the present invention provides an application of the textile PUR adhesive as described in the second aspect in the bonding of clothing fabrics.

[0033] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of PUR adhesive for textiles provided by the present invention has TPU uniformly dispersed, without layering, white spots, or precipitation, with a low probability of side reactions and high reaction stability. It can effectively avoid explosive polymerization and make the reaction more controllable, thereby effectively improving the stability of the obtained PUR adhesive, making it gel-free and with uniform viscosity. It also has excellent adhesion, water resistance and aging resistance, and is suitable for textile fabric composite, bonding and other scenarios. (2) The preparation method of PUR adhesive for textiles provided by the present invention has clear process parameters, can be stably scaled up for production, and is highly practical. Detailed Implementation

[0034] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0035] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0036] The raw materials involved in the following examples and comparative examples are all conventional materials in the art and can be obtained by purchasing commercially available products.

[0037] Example 1 A method for preparing a PUR adhesive for textiles includes the following steps: (1) 50 parts by weight of polycaprolactone polyol (Japan Daicel PCL 220 N, molecular weight 2000) were dehydrated at 120℃ and -0.098 MPa for 2 h to obtain dehydrated polycaprolactone polyol with a water content of ≤0.03%. Then, the obtained dehydrated polycaprolactone polyol and 15 parts by weight of TPU were mixed at 120℃ for 35 min until completely melted and homogeneous to obtain a mixture. (2) The mixture obtained in step (1) and 15 parts by weight of diphenylmethane diisocyanate (MDI) were reacted at 80°C for 2.5 h to obtain a polyurethane prepolymer; (3) The polyurethane prepolymer obtained in step (2) and 10 parts by weight of hydroxyethyl methacrylate (HEMA) were subjected to a grafting reaction at 60°C for 1.5 h to obtain an acrylic grafted polyurethane prepolymer. (4) The acrylic-grafted polyurethane prepolymer obtained in step (3) and 0.1 parts by weight of phosphoric acid are mixed at 45°C for 25 min, and then vacuum degassed for 30 min to obtain the PUR adhesive for textiles.

[0038] Example 2 A method for preparing a PUR adhesive for textiles includes the following steps: (1) 42 parts by weight of polycaprolactone polyol (Japan Daicel PCL 220 N, molecular weight 2000) were dehydrated at 115°C and -0.099 MPa for 1.5 h to obtain dehydrated polycaprolactone polyol with a water content of ≤0.03% by weight. Then, the obtained dehydrated polycaprolactone polyol and 11 parts by weight of TPU were mixed at 115°C for 40 min until completely melted and homogeneous to obtain a mixture. (2) The mixture obtained in step (1) and 10 parts by weight of diphenylmethane diisocyanate (MDI) were reacted at 76°C for 2 h to obtain a polyurethane prepolymer; (3) The polyurethane prepolymer obtained in step (2) and 5 parts by weight of hydroxyethyl methacrylate (HEMA) were reacted at 55°C for 1 h to obtain acrylic acid grafted polyurethane prepolymer. (4) The acrylic-grafted polyurethane prepolymer obtained in step (3) and 0.05 parts by weight of phosphoric acid are mixed at 40°C for 20 min, and then vacuum degassed for 30 min to obtain the PUR adhesive for textiles.

[0039] Example 3 A method for preparing a PUR adhesive for textiles includes the following steps: (1) 42 parts by weight of polycaprolactone polyol (Japan Daicel PCL 220 N, molecular weight 2000) were dehydrated at 115°C and -0.099 MPa for 1.5 h to obtain dehydrated polycaprolactone polyol with a water content of ≤0.03% by weight. Then, the obtained dehydrated polycaprolactone polyol and 11 parts by weight of TPU were mixed at 115°C for 40 min until completely melted and homogeneous to obtain a mixture. (2) The mixture obtained in step (1) and 10 parts by weight of diphenylmethane diisocyanate (MDI) were reacted at 76°C for 2 h to obtain a polyurethane prepolymer; (3) The polyurethane prepolymer obtained in step (2) and 5 parts by weight of hydroxyethyl methacrylate (HEMA) were reacted at 55°C for 1 h to obtain acrylic acid grafted polyurethane prepolymer. (4) The acrylic-grafted polyurethane prepolymer obtained in step (3) and 0.05 parts by weight of phosphoric acid are mixed at 45°C for 20 min, and then vacuum degassed for 30 min to obtain the PUR adhesive for textiles.

[0040] Example 4 A method for preparing a PUR adhesive for textiles, which differs from Example 1 only in that the reaction time in step (2) is only 1 h, while the other substances, amounts and steps are the same as in Example 1.

[0041] Example 5 A method for preparing a PUR adhesive for textiles, which differs from Example 1 only in that the reaction time in step (2) is 4 h, while the other substances, amounts and steps are the same as in Example 1.

[0042] Example 6 A method for preparing a PUR adhesive for textiles differs from Example 1 only in that an equimolar amount of polyoxypropylene ether diol (Shandong Lanxing Dongda, DL-2000D) is used to replace the polyester polyol. All other substances, amounts, and steps are the same as in Example 1.

[0043] Comparative Example 1 A method for preparing a PUR adhesive for textiles includes the following steps: (1) 50 parts by weight of polycaprolactone polyol (Japan Daicel PCL 220 N, molecular weight 2000) were dehydrated at 120℃ and -0.098 MPa for 2 h to obtain dehydrated polycaprolactone polyol with a water content of ≤0.03% by weight. The obtained dehydrated polycaprolactone polyol and 0.1 parts by weight of phosphoric acid were mixed at 45℃ for 25 min to obtain mixture A. (2) Mix the mixture A obtained in step (1) with 15 parts by weight of TPU at 120°C for 35 min until completely melted and homogeneous to obtain mixture B; (3) The mixture B obtained in step (2) and 15 parts by weight of diphenylmethane diisocyanate (MDI) were reacted at 80°C for 2.5 h to obtain a polyurethane prepolymer; (4) The polyurethane prepolymer obtained in step (3) and 10 parts by weight of hydroxyethyl methacrylate (HEMA) are reacted at 60°C for 1.5 h to obtain the PUR adhesive for textiles.

[0044] Comparative Example 2 A method for preparing a PUR adhesive for textiles includes the following steps: (1) 50 parts by weight of polycaprolactone polyol (Japan Daicel PCL 220 N, molecular weight 2000) were dehydrated at 120°C and -0.098 MPa for 2 h to obtain dehydrated polycaprolactone polyol with a water content of ≤0.03% by weight. Then, the obtained dehydrated polycaprolactone polyol and 15 parts by weight of TPU were mixed at 120°C for 35 min until completely melted and homogeneous to obtain a mixture. (2) The mixture obtained in step (1) and 15 parts by weight of diphenylmethane diisocyanate (MDI) and 10 parts by weight of hydroxyethyl methacrylate (HEMA) were reacted at 80°C for 2.5 h to obtain a polyurethane prepolymer; (3) The polyurethane prepolymer obtained in step (2) and 0.1 parts by weight of phosphoric acid are mixed at 45°C for 25 min, and then vacuum degassed for 30 min to obtain the PUR adhesive for textiles.

[0045] Performance testing: (1) Gel rate: Weigh a certain mass of PUR adhesive sample (m1), soak it in toluene for 24 h, filter it, and dry the insoluble matter at 105℃ to constant weight (m2). Calculate the gel rate according to the formula: gel rate = (m2 / m1)×100%; (2) Viscosity: A rotational viscometer was used at 120°C, with a suitable rotor selected, and the test was conducted at a rotational speed of 10 r / min. (3) Peel strength: According to GB / T 2792-2014 "Test method for peel strength of adhesive tape", the peel is 180°, the sample width is 25 mm, and the test speed is 100 mm / min; (4) Water resistance: The bonded textile sample (preparation method includes: selecting textile fabrics that meet the test requirements (such as common polyester, cotton or blended fabrics), cutting them into standard sizes (corresponding to the requirements of the 180° peel strength test, generally long strips with a length ≥200 mm and a width of 25 mm, each test requires at least 5 samples; gluing and bonding: uniformly apply molten PUR adhesive to the bonding surface of one textile sample, control the thickness of the adhesive layer (usually 0.1~0.3 mm, which can be adjusted according to the process), then align and bond the other textile sample, apply a certain pressure (such as 0.1~0.3 MPa) and cure it at room temperature or at a specified temperature for a sufficient time (such as 24 h) to ensure complete bonding; sample curing: after bonding, place the sample in a standard environment (temperature 23℃, humidity 50%RH) for curing, and ensure that the performance is stable before testing) and immerse it in room temperature water for 24 hours. h, test the peel strength before and after immersion, calculate the peel strength retention rate, water resistance = (peel strength after immersion / initial peel strength) × 100%; (5) Batch stability: Take 3 batches of adhesive produced continuously and test their viscosity at 120℃ to calculate the viscosity fluctuation deviation.

[0046] The textile PUR adhesives provided in Examples 1-6 and Comparative Examples 1-2 were tested according to the above preparation method, and the test results are shown in Table 1. Table 1 According to the data in Table 1: The PUR adhesives for textiles prepared by the methods provided in Examples 1-6 all have a gel rate of 0% and a viscosity of 9500-11000 mPa·, and exhibit high batch stability. When further used in textile samples, they can guarantee a peel strength of up to 14-17 N / 25 mm, and the peel strength retention rate after water immersion is not less than 90%, demonstrating excellent water resistance.

[0047] Compared with Examples 1-6, the textile PUR adhesive obtained by the preparation method provided in Comparative Example 1 is completely gelled, while the textile PUR adhesive obtained by the preparation method provided in Comparative Example 2 has a gelation rate as high as 80%, excessively high viscosity, low peel strength, and poor water resistance.

[0048] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a PUR adhesive for textiles, characterized in that, The preparation method includes the following steps: (1) Polyol and TPU are melt-blended to obtain a mixture; (2) React the mixture obtained in step (1) with isocyanate to obtain a polyurethane prepolymer; (3) React the polyurethane prepolymer obtained in step (2) with acrylic monomers to obtain acrylic grafted polyurethane prepolymer; (4) The acrylic-grafted polyurethane prepolymer obtained in step (3) is mixed with phosphoric acid to obtain the PUR adhesive for textiles.

2. The preparation method according to claim 1, characterized in that, The raw materials for the textile PUR adhesive comprise the following components in parts by weight: 40-60 parts by weight of polyol; 10-25 parts by weight of TPU; 10-20 parts by weight of isocyanate; 5-15 parts by weight of acrylic monomers; Phosphoric acid 0.05~0.3 parts by weight.

3. The preparation method according to claim 1 or 2, characterized in that, The polyols include polyester polyols; Preferably, before the melt blending in step (1), the polyol is further subjected to dehydration treatment at 115~125℃ and a vacuum degree of -0.095 MPa or higher for 1.5~2.5 h to obtain the dehydrated polyol; Preferably, the water content in the dehydrated polyol is ≤0.03% by mass.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The melt blending temperature in step (1) is 115~125℃; Preferably, the melt blending time in step (1) is 30~40 min.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The isocyanate includes aromatic isocyanates; Preferably, the reaction temperature in step (2) is 75~90℃; Preferably, the reaction time in step (2) is 2 to 3 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The acrylic monomers include hydroxy acrylic monomers; Preferably, the hydroxyacrylate monomer includes hydroxyethyl methacrylate; Preferably, the reaction temperature in step (3) is 55~60℃; Preferably, the reaction time in step (3) is 1 to 2 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The mixing temperature in step (4) is 20~45℃; Preferably, the mixing time in step (4) is 20 to 30 minutes.

8. The preparation method according to any one of claims 1 to 7, characterized in that, After the mixing process is completed in step (4), a vacuum degassing step is also included.

9. A PUR adhesive for textiles, characterized in that, The textile PUR adhesive is prepared using the preparation method described in any one of claims 1 to 8.

10. The application of the PUR adhesive for textiles as described in claim 9 in the bonding of clothing fabrics.

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