A recyclable slurry and its preparation, application and recycling method

Abstract

The present invention relates to the field of slurry technology, and specifically to a recyclable slurry and its preparation, application and recycling methods. The slurry comprises the following raw materials in the following weight percentages: 70-80% water-dispersible degradable polyurethane resin, 5-10% wax slurry, and 10-20% foaming powder; the recyclable slurry foams at a specific temperature, and the specific temperature is greater than the highest temperature of the cloth coated with the recyclable slurry when it is prepared as a finished product. The slurry comprises a specific proportion of water-dispersible degradable polyurethane resin, wax slurry and foaming powder. The adhesion of this slurry is normal and no different from that of ordinary slurry below the specific temperature. When recycling is required, the cloth coated with the recyclable slurry is placed in an environment above the specific temperature. The slurry foams and expands, and its strength decreases. Since the expanded wax particles are squeezed to the contact surface of the cloth and the slurry, the peeling strength of the two is reduced, so that the slurry can be easily torn off and clean cloth can be recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of slurry, and in particular to a recyclable slurry and a preparation, application and recycling method thereof. Background Art

[0002] As the environment deteriorates, various recycling issues have gradually become the research focus of various companies. There are physical and chemical methods for recycling simple polyester fabrics, and the process is mature. The polyurethane coating on the fabric is usually recyclable by using a degradable polyurethane coating. For example, the Chinese invention patent with application number 202310793788.5 discloses a synthetic leather based on recyclable bio-based polyurethane resin and its preparation method. Recyclable bio-based polyurethane resin and other materials are used according to different formulas to make impregnation materials for impregnation, knife coatings for knife coating, and back coatings for back coating. The final synthetic leather not only has a high recycling rate, but also has high hydrolysis resistance. However, when recycling this synthetic leather, it is necessary to wait for the coating to degrade naturally before recycling the fabric, which takes a long time, and it is difficult to separate the synthetic leather and polyurethane. After degradation, the polyurethane easily remains on the synthetic leather, and the removal rate is not high. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: a recyclable slurry with short recovery time and high removal rate and a preparation, application and recycling method thereof.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a recyclable slurry, comprising the following raw materials in the following weight percentages: 70-80% water-dispersible biodegradable polyurethane resin, 5-10% wax slurry, and 10-20% foaming powder; the recyclable slurry foams at a specific temperature, and the specific temperature is greater than the maximum temperature of the fabric coated with the recyclable slurry when it is prepared as a finished product.

[0005] Another technical solution of the present invention is: the preparation method of the above-mentioned recyclable slurry is to first add water-dispersible degradable polyurethane resin and stir it, then add wax slurry, foaming powder and additives during stirring, and continue stirring until uniform.

[0006] Another technical solution of the present invention is: the application method of the above-mentioned recyclable slurry comprises the following steps:

[0007] S1: Add curing agent to the recyclable slurry and stir it evenly before coating it on the fabric. After drying, a recyclable slurry coating is obtained.

[0008] S2: Apply other coatings on the recyclable slurry coating.

[0009] Another technical solution of the present invention is: the above-mentioned method for recycling recyclable slurry is to place the cloth coated with recyclable slurry in an environment with a specific temperature until the coating of the recyclable slurry expands, and then tear off the coating to obtain clean cloth.

[0010] The beneficial effects of the present invention are as follows: the recyclable slurry of the present invention comprises a specific ratio of water-dispersible biodegradable polyurethane resin, wax slurry, and foaming powder. The recyclable slurry has normal adhesion, similar to that of ordinary slurry, below a specific temperature, and does not affect the subsequent production of the fabric or the physical properties of the finished product. When recycling is required, the fabric coated with the recyclable slurry is placed in an environment above the specific temperature. The recyclable slurry coating foams and expands, reducing its strength. The expanded wax particles are squeezed onto the contact surface between the fabric and the recyclable slurry coating, reducing the peel strength between the two. This allows the recyclable slurry coating to be easily removed, allowing for the recovery of clean fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a diagram showing the finished product obtained in Example 5 of the present invention without high temperature treatment;

[0012] Figure 2 FIG2 is a diagram showing the finished product after high temperature treatment in Example 8 of the present invention. DETAILED DESCRIPTION

[0013] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the embodiments and accompanying drawings.

[0014] A recyclable slurry comprises the following raw materials in percentage by weight: 70-80% water-dispersible degradable polyurethane resin, 5-10% wax slurry, and 10-20% foaming powder. The recyclable slurry foams at a specific temperature, which is greater than the maximum temperature of the cloth coated with the recyclable slurry when it is prepared as a finished product.

[0015] Preferably, the raw materials include the following weight percentages: 75-80% water-dispersible degradable polyurethane resin, 5-8% wax slurry, and 15-20% foaming powder.

[0016] Preferably, the raw materials include the following weight percentages: 70-80% water-dispersible degradable polyurethane resin, 5-10% wax slurry, 10-20% foaming powder and 1.8-4.6% auxiliary agent.

[0017] As can be seen from the above description, the beneficial effects of the present invention are as follows: the recyclable slurry of the present invention controls the amount of water-dispersible degradable polyurethane resin, wax slurry, and foaming powder added, so that when the recyclable slurry is applied, the wax slurry is encapsulated within the coating, ensuring normal adhesion below a specific temperature, without affecting the subsequent production of the fabric or the physical properties of the finished product. When the coating needs to be removed, the fabric coated with the recyclable slurry is placed in an environment above a specific temperature. The coating foams and expands, reducing its strength. The wax particles in a specific content are squeezed onto the contact surface between the fabric and the recyclable slurry coating after expansion, reducing the peel strength between the two. This allows the recyclable slurry coating to be easily removed, resulting in clean fabric recovery. The recyclable slurry of the present invention can achieve 100% coating removal, significantly accelerating recycling time. Under external temperature and humidity conditions, the degradable resin is absorbed and decomposed into carbon dioxide and other compounds by microorganisms. The foaming of the water-dispersible degradable polyurethane resin creates pores, increasing its contact area with the environment and also increasing the degradation rate of the water-dispersible degradable polyurethane resin.

[0018] The water-dispersible biodegradable polyurethane resin, wax slurry, and foaming powder are added in specific proportions: Excessive wax slurry addition can affect the adhesion and bending resistance of the recyclable slurry coating before high-temperature recycling. Excessive wax slurry addition can prevent the coating from completely migrating to the bottom of the recyclable slurry coating after expansion, reducing the removal rate of the recyclable slurry coating. Excessive foaming powder addition can reduce the tearing effect of the recyclable slurry coating; excessive foaming powder addition can affect the bending resistance of the recyclable slurry coating before high-temperature recycling.

[0019] Furthermore, the recyclable slurry is foamed at a temperature ≥ 200°C.

[0020] Another technical solution of the present invention is: the preparation method of the above-mentioned recyclable slurry is to first add water-dispersible degradable polyurethane resin and stir it, then add wax slurry, foaming powder and additives during stirring, and continue stirring until uniform.

[0021] From the above description, it can be seen that the preparation method is simple and efficient, and does not require the purchase of additional equipment, and can be directly applied to existing production.

[0022] Furthermore, the auxiliary agent includes the following components and the weight percentage of each component in the total raw materials is: 0.1-0.2% pH regulator, 0.1-0.3% defoamer, 0.5-0.6% dispersant, 1.1-2.3% thickener and 0.5-1.2% solvent.

[0023] As can be seen from the above description, the pH regulator is used to enhance the stability of the slurry's viscosity; the defoamer reduces foaming during the slurry preparation process, improving its stability; the dispersant disperses the foam powder and wax slurry; and the thickener increases the slurry's viscosity, making it suitable for coating. The recyclable slurry prepared using the formulation of the present invention has physical properties similar to conventional slurries at room temperature, allowing it to be applied directly to existing production processes without the need for additional special steps.

[0024] Further, the thickener includes PU (polyurethane) thickener and acrylic thickener.

[0025] Furthermore, the mass ratio of the PU thickener to the acrylic thickener is 1 to 13:1.

[0026] From the above description, it can be seen that PU thickener focuses on making the slurry obtain Newtonian fluid viscosity; acrylic thickener focuses on making the slurry obtain non-Newtonian fluid viscosity. The combination of the two thickeners can adapt to the shear viscosity changes during printing.

[0027] Furthermore, the solvent is propylene glycol.

[0028] Another technical solution of the present invention is: the application method of the above-mentioned recyclable slurry comprises the following steps:

[0029] S1: Add curing agent to the recyclable slurry and stir it evenly before coating it on the fabric. After drying, a recyclable slurry coating is obtained.

[0030] S2: Apply other coatings on the recyclable slurry coating.

[0031] As can be seen from the above description, the application method of the present invention has a wide range of applications, and other coatings can be applied on top of the recyclable slurry of the present invention to achieve 100% recycling of the coating.

[0032] Furthermore, the thickness of the recyclable slurry coating is 0.2 to 0.3 mm.

[0033] From the above description, it can be seen that the higher the film thickness of the recyclable slurry, the higher its foaming degree, but at the same time its bending resistance decreases. When the thickness of the recyclable slurry coating is 0.2-0.3mm, it is the most suitable thickness for bending resistance and foaming degree.

[0034] Furthermore, the recyclable slurry coating is applied once or at least twice.

[0035] Furthermore, the other coating is a degradable water-based polyurethane resin coating.

[0036] From the above description, it can be seen that the degradable water-based polyurethane resin coating is degradable and more environmentally friendly, and the recyclable slurry includes water-dispersible degradable polyurethane resin, which has high peel strength with the degradable water-based polyurethane resin coating and is not easy to fall off after production.

[0037] Furthermore, the degradable water-based polyurethane resin coating is prepared from the following raw materials in weight percentage: 85-90% water-dispersible degradable polyurethane resin, 0.1-0.2% pH regulator, 0.1-0.3% silicone defoamer, 0.5-0.6% dispersant, 1.0-1.3% PU thickener, 5.0-8.0% fumed silica powder, 0.1-1.0% acrylic thickener and 0.5-3.6% propylene glycol.

[0038] From the above description, it can be seen that adding fumed silica powder to the degradable water-based polyurethane resin coating can improve the wear resistance.

[0039] Furthermore, the added amount of the curing agent is 3 to 5%.

[0040] From the above description, it can be seen that the coating parameters and curing conditions can be controlled by controlling the amount of curing agent added.

[0041] Furthermore, the curing agent is an isocyanate curing agent.

[0042] From the above description, it can be seen that the curing temperature required by the isocyanate curing agent is not high. It can be cured during the drying process at 40-50°C. The reaction speed is moderate and easy to operate.

[0043] Furthermore, coating can be performed by any existing coating method such as printing, screen printing, brushing, etc.

[0044] Furthermore, the drying temperature in S1 is 50-80°C.

[0045] From the above description, it can be seen that drying at 50-80°C can accelerate drying and curing without generating too high a temperature to cause direct foaming of the recyclable slurry coating, thereby affecting the physical properties of the finished product.

[0046] Another technical solution of the present invention is: the above-mentioned method for recycling recyclable slurry is to place the cloth coated with recyclable slurry in an environment with a specific temperature until the coating of the recyclable slurry expands, and then tear off the coating to obtain clean cloth.

[0047] From the above description, it can be seen that when the cloth coated with the recyclable slurry is placed in an environment with a specific temperature, the recyclable slurry coating expands and its strength decreases. After expansion, the wax particles are squeezed to the contact surface between the cloth and the recyclable slurry coating, so that the recyclable slurry coating can be easily torn off, achieving a removal rate of 100%.

[0048] The following examples include the following types of raw materials: water-dispersible biodegradable polyurethane resin: Covestro water-based polyurethane resin Impranil DLN-SD; pH adjuster: Dow Chemical Company AMP-95; silicone defoamer: Digo TEGO 825; dispersant: Digo TEGO 755W; wax slurry: Siluoke XH-8008; PU thickener: Lamberti PS166; foaming powder: Aksu Expancel 980DU 120; acrylic thickener: Dow Rohm and Haas ASE-60; propylene glycol; fumed silica powder: Cabot M-5; sandwich mesh: the upper and lower surface yarns are polyester, and the middle connecting yarn is polyester monofilament.

[0049] Embodiment 1 of the present invention is: a method for preparing a recyclable slurry, the steps of which are as follows: first, 760g of water-dispersible biodegradable polyurethane resin is added to a dispersion tank, the disperser is turned on and stirred at room temperature at a rate of 800rpm / min, 1.5g of pH regulator, 2g of silicone defoamer, 5.5g of dispersant, 100g of wax slurry, 11g of PU thickener, 100g of foaming powder, 10g of acrylic thickener and 10g of propylene glycol are added in sequence during stirring, and stirring is continued until uniform. The viscosity of the recyclable slurry is 120,000cps.

[0050] Embodiment 2 of the present invention is: a method for preparing a recyclable slurry, the steps of which are as follows: first, add 700g of water-dispersible degradable polyurethane resin into a dispersion tank, turn on the disperser and stir at room temperature at a rate of 800rpm / min, and add 2g of pH regulator, 3g of silicone defoamer, 6g of dispersant, 59g of wax slurry, 13g of PU thickener, 200g of foaming powder, 5g of acrylic thickener and 12g of propylene glycol in sequence during stirring, and continue stirring until uniform.

[0051] Embodiment 3 of the present invention is: a method for preparing a recyclable slurry, the steps of which are as follows: first, add 800g of water-dispersible degradable polyurethane resin into a dispersion tank, turn on the disperser and stir at room temperature at a rate of 800rpm / min, and add 1g of pH regulator, 1g of silicone defoamer, 5g of dispersant, 50g of wax slurry, 10g of PU thickener, 127g of foaming powder, 1g of acrylic thickener and 5g of propylene glycol in sequence during stirring, and continue stirring until uniform.

[0052] Comparative Example 1 of the present invention is:

[0053] The only difference between Comparative Example 1 and Example 1 is that the added amount of foaming powder is 50 g, the added amount of water-dispersible degradable polyurethane resin is 810 g, and the viscosity of the recyclable slurry is 90,000 cps.

[0054] Comparative Example 2 of the present invention is:

[0055] The only difference between Comparative Example 2 and Example 1 is that the amount of foaming powder added is 250 g, the amount of water-dispersible degradable polyurethane resin added is 610 g, and the viscosity of the recyclable slurry is 120,000 cps.

[0056] The fourth embodiment of the present invention is: a recyclable slurry prepared by the preparation method of the first embodiment.

[0057] The fifth embodiment of the present invention is: the application method of the recyclable slurry of the fourth embodiment, characterized by comprising the following steps:

[0058] S1: 40 g of isocyanate curing agent was added to the recyclable slurry and stirred to obtain a mixture. The mixture was first screen-printed twice on a sandwich mesh and dried at 80° C. to obtain a recyclable slurry coating; the thickness of the recyclable slurry coating was 0.25 mm;

[0059] S2: 889 g of water-dispersible biodegradable polyurethane resin was added to a dispersion tank, and the disperser was turned on and stirred at room temperature at a rate of 800 rpm / min. 1.5 g of pH regulator, 2 g of silicone defoamer, 5.5 g of dispersant, 10 g of PU thickener, 78 g of fumed silica powder, 9 g of acrylic thickener, and 5 g of propylene glycol were added in sequence during stirring, and stirring was continued until uniform to obtain a water-based biodegradable polyurethane resin slurry; the viscosity of the water-based biodegradable polyurethane resin slurry was 110,000 cps;

[0060] S4: Use a screen to print a water-based biodegradable polyurethane resin slurry on the recyclable slurry coating under the same printing conditions as S1, and place the printed product in a 50°C oven to dry for 8 hours to obtain a finished product. Figure 1 ;

[0061] The screen needs to be cleaned after each printing process is completed.

[0062] The sixth embodiment of the present invention is: the application method of the recyclable slurry of the fourth embodiment, characterized by comprising the following steps:

[0063] S1: 30 g of isocyanate curing agent was added to the recyclable slurry and stirred to obtain a mixture. The mixture was first screen-printed twice on a sandwich mesh and dried at 80° C. to obtain a recyclable slurry coating; the thickness of the recyclable slurry coating was 0.2 mm;

[0064] S2: Add 850 g of water-dispersible biodegradable polyurethane resin into a dispersion tank, turn on the disperser and stir at room temperature at a rate of 800 rpm / min. Add 2 g of pH regulator, 3 g of silicone defoamer, 6 g of dispersant, 13 g of PU thickener, 80 g of fumed silica powder, 10 g of acrylic thickener and 5-36 g of propylene glycol in sequence during stirring, and continue stirring until uniform to obtain a water-based biodegradable polyurethane resin slurry; the viscosity of the water-based biodegradable polyurethane resin slurry is 110,000 cps;

[0065] S4: Printing a water-based biodegradable polyurethane resin slurry on the recyclable slurry coating using a screen, and drying the printed product in an oven at 50° C. for 8 hours to obtain a finished product;

[0066] The screen needs to be cleaned after each printing process is completed.

[0067] The seventh embodiment of the present invention is: the application method of the recyclable slurry of the fourth embodiment, characterized by comprising the following steps:

[0068] S1: adding 50 g of isocyanate curing agent to the recyclable slurry and stirring to obtain a mixture, first printing the mixture twice on a sandwich mesh with a screen and drying it at 50° C. to obtain a recyclable slurry coating; the thickness of the recyclable slurry coating is 0.3 mm;

[0069] S2: Add 900 g of water-dispersible biodegradable polyurethane resin into a dispersion tank, turn on the disperser and stir at room temperature at a rate of 800 rpm / min. Add 1 g of pH regulator, 1 g of silicone defoamer, 5 g of dispersant, 10 g of PU thickener, 70 g of fumed silica powder, 1 g of acrylic thickener and 12 g of propylene glycol in sequence during stirring, and continue stirring until uniform to obtain a water-based biodegradable polyurethane resin slurry; the viscosity of the water-based biodegradable polyurethane resin slurry is 110,000 cps;

[0070] S4: Printing a water-based biodegradable polyurethane resin slurry on the recyclable slurry coating using a screen, and drying the printed product in an oven at 50° C. for 8 hours to obtain a finished product;

[0071] The screen needs to be cleaned after each printing process is completed.

[0072] Comparative Example 3 of the present invention is:

[0073] The only difference between Comparative Example 3 and Example 1 is that steps S1 and S2 are omitted, and the water-based degradable polyurethane resin slurry is directly printed on the sandwich mesh.

[0074] The eighth embodiment of the present invention is: the finished product prepared in the fifth embodiment is recycled, and the finished product is baked at 200°C for 1 minute. Figure 2After baking, the recyclable slurry coating is removed to obtain a clean cloth.

[0075] The recyclable slurries obtained by the preparation methods of Example 1, Comparative Examples 1, and Comparative Examples 2 were respectively applied using the method of Example 5 to obtain Samples 1-3; Sample 4 was obtained using the preparation method of Comparative Example 3. The differences between Samples 1-4 are shown in Table 1. Adhesion and bending resistance tests were performed on Samples 1-4. Samples 1-4 were then baked at 200°C for 1 minute and then retested for adhesion and bending resistance. The test results are shown in Table 2.

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080] As shown in Table 2, Samples 1 and 4 demonstrate that the recyclable slurry and recycling method of the present invention achieve the same physical properties as conventional adhesives at room temperature, while enabling easy removal after high-temperature foaming. Comparing Sample 1 with Samples 2-3 reveals that too little foaming powder reduces the recyclable slurry coating's removability, while excessive amounts can affect the flexural resistance of the recyclable slurry coating before high-temperature recycling.

[0081] In summary, the recyclable slurry provided by the present invention achieves the technical effect of having the same physical properties as conventional adhesive at room temperature and being easily removable after high-temperature foaming by controlling the addition amounts of water-dispersible biodegradable polyurethane resin, wax slurry, and foaming powder. This recyclable slurry and its preparation, application, and recycling methods have the following advantages:

[0082] 1. The recyclable slurry contains a specific amount of wax slurry, so that when the recyclable slurry is coated, the wax slurry is wrapped in the coating, which does not affect the subsequent production of the fabric and the physical properties of the finished product; when the coating needs to be removed, the wax particles are squeezed to the contact surface of the fabric and the recyclable slurry coating after foaming and expanding at high temperature, reducing the peeling strength between the two, so that the recyclable slurry coating can be easily torn off and clean fabric can be recycled.

[0083] 2. After foaming, the water-dispersible degradable polyurethane resin produces pores, which increases its contact area with the environment and also increases the degradation rate of the water-dispersible degradable polyurethane resin.

[0084] 3. Using a specific proportion of foaming powder to achieve high temperature tearing while maintaining its bending resistance.

[0085] 4. The preparation and application methods of the recyclable slurry are simple, suitable for existing processes and equipment, and can be directly applied to existing production.

[0086] 5. The recyclable pulp is recycled under specific high temperature conditions to achieve an anti-counterfeiting effect.

[0087] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A recyclable slurry, characterized in that: The recyclable slurry comprises the following raw materials in percentage by weight: 70-80% water-dispersible degradable polyurethane resin, 5-10% wax slurry, and 10-20% foaming powder; the recyclable slurry foams at a temperature of 200°C.

2. A method for preparing the recyclable slurry according to claim 1, characterized in that: First add water-dispersible biodegradable polyurethane resin and stir, then add wax slurry, foaming powder and additives during stirring, and continue stirring until uniform.

3. The method for preparing recyclable slurry according to claim 2, characterized in that: The auxiliary agent includes the following components, and the weight percentage of each component in the total raw materials is: 0.1-0.2% pH regulator, 0.1-0.3% defoamer, 0.5-0.6% dispersant, 1.1-2.3% thickener and 0.5-1.2% solvent.

4. The method for preparing recyclable slurry according to claim 3, characterized in that: The thickener includes PU thickener and acrylic thickener.

5. The method for preparing recyclable slurry according to claim 4, characterized in that: The mass ratio of the PU thickener to the acrylic thickener is 1-13:

1.

6. The method for preparing recyclable slurry according to claim 3, characterized in that: The solvent is propylene glycol.

7. A method for applying the recyclable slurry according to claim 1, characterized in that: The following steps are involved: S1: Add curing agent to the recyclable slurry and stir it evenly before coating it on the fabric. After drying, a recyclable slurry coating is obtained. S2: Apply other coatings on the recyclable slurry coating.

8. The method for applying the recyclable slurry according to claim 7, characterized in that: The drying temperature in S1 is 50-80°C.

9. A method for recovering recyclable slurry according to claim 1 or 2, characterized in that: The cloth coated with the recyclable slurry is placed in an environment of 200° C. until the coating of the recyclable slurry expands, and the coating is removed to obtain a clean cloth.

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