TWI852067B - A continuous production method of TPU foam leather - Google Patents

Abstract

A continuous production method of TPU foamed leather comprises the following steps: step 1, preparing the following raw materials: diisocyanate, chain expander, polymer diol and polyethylene glycol; step 2, inputting the raw materials into a reaction container for mixing; step 3, inputting a foaming agent and calcium carbonate into the reaction container to form a melt; step 4, extending the melt to form a TPU film; step 5, inputting a cloth, and laminating the TPU film and the cloth to form a foaming substrate; step 6, softening the foaming substrate; step 7, foaming the foaming substrate to form TPU foamed leather. The TPU foamed leather produced by the production method of the present invention can meet the increasingly stringent environmental protection requirements and has good physical properties. At the same time, it can avoid the collapse problem caused by shear force, pre-foaming and static electricity and has good uniformity.

Description

A continuous production method of TPU foam leather

The present invention relates to the field of TPU foam leather, and in particular to a continuous production method of TPU foam leather.

At present, the market's environmental protection requirements for the synthetic leather and artificial leather industries are becoming increasingly stringent:

PVC artificial leather has many advantages such as the comprehensive feel of various artificial leathers, product diversity, and bright colors, which makes its products popular to this day. It is usually processed by calendering machines. Calendering machines are currently the most efficient equipment for polymer plastic processing and can consume plastics at a rate of 10~20kg/min. However, the physical properties of PVC artificial leather are poor, it is easy to age and crack, and it is not environmentally friendly. In addition, the PVC used in artificial leather contains a large amount of plasticizers, and its main ingredient DEHP has been proven to cause hormone mutations in humans and may even have a carcinogenic risk.

Since polyurethane synthetic leather can solve the problem of physical properties, it replaced a considerable proportion of the artificial leather market in the 1970s, making many high-end leather products with high physical properties use polyurethane synthetic leather. However, since the polyurethane material used in synthetic leather contains a large amount of solvents, especially DMF (dimethylformamide), many medical reports directly point out that it has obvious serious harm to the skin, respiratory tract, liver, etc., and is also suspected of having a carcinogenic risk.

TPU (thermoplastic polyurethane elastomer) has excellent physical properties and no solvent problems, and can be used to replace synthetic leather and artificial leather. At present, most manufacturers use calenders to make TPU films, then compound the TPU films with fabrics, and finally foam them to form TPU foam leather (refer to the preparation method of environmentally friendly flame-retardant and UV-resistant TPU foam leather disclosed in Chinese invention application CN107164972A).

However, the existing TPU foam leather production method usually adopts a segmented independent production process. Specifically, TPU particles are first produced (or TPU particles are directly purchased from the market), and then the TPU particles are successively put into a compacting machine and an open-calender for compacting and open-calendering, so that the TPU material is mixed with other materials, and then put into a calender to produce a TPU film. The TPU foam leather obtained by this production method has poor uniformity, and often has product dents. Some even have a sharp decline in physical properties. The fundamental reason is that the molecular chain of TPU is filled with a large number of hydrogen bonds. Due to the van der Waals force, the shear stress of the product is too large, and a large friction force is generated between it and the roller of the calender in the molten state, affecting its flow rate in the calender. The unstable flow rate causes different times for applying pressure to different positions of the TPU film, which ultimately affects the uniformity of the TPU foam leather.

Adding an appropriate amount of lubricant can solve the above problems. However, in the case of mass production, the amount of lubricant added is difficult to control accurately: adding a slightly insufficient amount will result in the problem of uniformity cannot be completely solved, and adding a slightly excessive amount will cause the calender's turbine to idle.

In addition, increasing the equipment temperature can also reduce shear stress. However, after adding the foaming agent, when the equipment temperature reaches above 210°C, the TPU film will be partially pre-foamed, and there is also the problem of poor uniformity.

In view of this, we, the inventors, have devoted ourselves to further research on the continuous production method of TPU foam leather, and have started to carry out research and development and improvement, hoping to find a better invention to solve the above problems. After continuous testing and modification, the present invention was born.

The technical solution of the present invention is aimed at the above situation, and in order to solve the above problem, a continuous production method of TPU foam leather is provided, and the continuous production method comprises the following steps:

Step 1, prepare the following raw materials: diisocyanate, chain expander, polymer diol and polyethylene glycol, the temperature of diisocyanate and chain expander is 65-75°C, the temperature of polymer diol and polyethylene glycol is 85-95°C;

Step 2: Mix the raw materials at a mixing temperature of 170-220°C;

Step 3, adding a foaming agent, the temperature of the foaming agent is 170-190°C, forming a melt with a temperature of 170-190°C;

Step 4: stretching the melt at a temperature of 170-190° C. to form a TPU film;

Step 5: Laminating the TPU film with the fabric at a laminating temperature of 180-200°C to form a foaming substrate;

Step 6: Softening the foaming substrate at a softening temperature of 170-190°C;

Step 7: Foaming the foaming substrate at a foaming temperature of 210-240° C. to form TPU foamed leather.

Furthermore, in step 1, the following raw materials are also prepared: an antioxidant and an anti-yellowing agent, and the temperature of the antioxidant and the anti-yellowing agent is 85-95°C.

Further, in step 1, the diisocyanate is one or a mixture of MDI and TDI; the chain expander is one or a mixture of 1,4BG and EG; the high molecular diol is one or more mixtures of AA/EG, AA/1,4BG, PCL, PC, PTMEG and PPG; the antioxidant is one or more mixtures of 1010 antioxidant, 1076 antioxidant, 1098 antioxidant and 168 antioxidant; the anti-yellowing agent is one or more mixtures of UV-328, UV-327, UV-P and UV-765; in step 3, the blowing agent is one or more mixtures of DIPA, BaAC, azoaminobenzene, ADCA, DPT, PTSS, benzenesulfonyl chloride and THT.

Furthermore, in step 1, the hydroxyl value of the polymer diol is 20-200, the hydroxyl value of the polyethylene glycol is 30-600, and the resistance value is 1×10 ¹¹ ~9×10 ¹² Ω.

Furthermore, in step 2, the flow rate of the input diisocyanate is 1-3 kg/min, the flow rate of the input chain expander is 0.2-1 kg/min, and the flow rate of the input polymer diol, polyethylene glycol, antioxidant and anti-yellowing agent is 2-4 kg/min.

Furthermore, in step 2, the following steps are included:

Step 2.1, subjecting the raw materials to forced polymerization at a temperature of 200-220°C;

Step 2.2: subject the raw materials to forced cooling at a temperature of 170-190°C.

Furthermore, in step 3, the following steps are included:

Step 3.1, adding a foaming agent and calcium carbonate, the temperature of the foaming agent and calcium carbonate are both 170-190°C;

Step 3.2: Filter the raw materials to form a melt with a temperature of 170-190°C.

Furthermore, in step 7, the following steps are included:

Step 7.1, performing initial foaming on the foaming substrate at a temperature of 210-220°C;

Step 7.2, foaming the foaming substrate in large quantities at a temperature of 220-230° C.;

Step 7.3: Fully foam the foam substrate at a temperature of 230-240°C to form TPU foamed leather.

Furthermore, the continuous production method further comprises the following steps: Step 8, cooling the TPU foam leather at a cooling temperature of 150-160°C.

Furthermore, the continuous production method further comprises the following steps:

Step 9, embossing the TPU foam leather;

Step 10: Cooling and rolling up the embossed TPU foam leather.

After adopting the above technical solution, the beneficial effects of the present invention are:

1. The production method of the present invention adopts a segmented continuous production method, which can ensure that TPU has not yet formed or has only a trace amount of hydrogen bonds during the production process, so that its shear force is relatively small, and the friction force can be reduced in the subsequent extension process, thereby improving the uniformity of the TPU foamed leather.

2. The production method of the present invention can accurately control the temperature before adding the foaming agent, which can effectively avoid the pre-foaming phenomenon. The material foams simultaneously in the foaming furnace, thereby ensuring the uniformity of the TPU foamed leather.

3. The production method of the present invention adds polyethylene glycol to the raw materials, which can enable the melt itself to overcome the problem of electrostatic charge accumulation, eliminate the resistance problem caused by static electricity, ensure the smoothness of the entire production process, and thus ensure the uniformity of the TPU foamed leather.

4. The TPU foam leather produced by the production method of the present invention can meet the increasingly stringent environmental protection requirements and has good physical properties.

Regarding the technical means of our inventors, several preferred embodiments are described in detail below with reference to the drawings so that you can have a deeper understanding and recognize the present invention.

The present invention provides a continuous production method for TPU foamed leather. As shown in FIG1 , the continuous production method mainly uses a filling machine, a reaction-type twin-screw extruder, a calender and a foaming furnace, and specifically includes the following steps:

The first stage is to prepare the melt:

Step 1: prepare the following raw materials in a filling machine: diisocyanate, chain expander, polymer diol and polyethylene glycol. The temperature of diisocyanate and chain expander is 65-75°C, and the temperature of polymer diol and polyethylene glycol is 85-95°C.

Step 2, pouring the raw materials in the pouring machine into the reactive twin-screw extruder for mixing, and the mixing temperature is 170-220°C;

Step 3, adding a foaming agent to a reactive twin-screw extruder, wherein the temperature of the foaming agent is 170-190° C., to form a melt having a temperature of 170-190° C.;

The second stage is to make the foam substrate:

Step 4, extruding the melt from the reactive twin-screw extruder to a calender for stretching at a stretching temperature of 170-190°C to form a TPU film;

Step 5: Feed the fabric into the calender, and laminate the TPU film to the fabric at a laminating temperature of 180-200°C to form a foaming substrate;

The third stage is to make TPU foam leather:

Step 6: feeding the foaming substrate in the calender into the foaming furnace to soften the foaming substrate at a softening temperature of 170-190°C;

Step 7: Foaming the foaming substrate at a foaming temperature of 210-240° C. to form TPU foamed leather.

The TPU foam leather produced by the present invention in a segmented continuous manner has good uniformity, and the key lies in:

1. Compared with the segmented independent production method used in the prior art, the present invention does not directly add the prepared TPU particles, but adopts a segmented continuous production method. The TPU raw materials are mixed and then directly extended. At this time, since the TPU has not undergone a process of cooling to room temperature, no or only a trace amount of hydrogen bonds have been formed in the TPU, and the van der Waals force is small, so its shear force is small, which can reduce friction in the subsequent extension process, thereby improving the uniformity of the TPU foamed leather.

2. After adding the foaming agent, the temperature of the material is kept at 170~190℃ until foaming, which can effectively avoid the phenomenon of pre-foaming. The material foams at the same time in the foaming furnace, thereby ensuring the uniformity of the TPU foamed leather.

3. The present invention adds polyethylene glycol to the raw materials to make TPU have anti-static properties. It is worth mentioning that the purpose of adding polyethylene glycol is not only to make TPU foam leather have anti-static properties, but also to avoid static electricity generated by friction between the melt and the conveying roller of the calender during the production process, thereby forming resistance and affecting the transmission rate. Specifically, although the friction between the melt and the conveying roller of the present invention is relatively small, there is still a phenomenon of mutual friction. At present, the methods of eliminating static electricity in the production process of TPU foam leather mainly include physical elimination and chemical elimination: the physical elimination method generally involves humidifying the workplace to avoid the formation of static electricity, but for large-area production, the humidification method can only eliminate local static electricity in the melt, and it is difficult to ensure that the entire surface does not generate static electricity; the chemical elimination method generally involves adding a hydrophilic surfactant to the surface of the melt. This method can indeed eliminate static electricity on the entire surface of the melt, but as the conveyor roller rolls, the hydrophilic surfactant on the surface will inevitably fall off, thereby losing the effect of eliminating static electricity. In addition, this method cannot be applied to products with greater thickness (i.e., deep static electricity cannot be eliminated). After adding polyethylene glycol, the present invention can make the melt itself overcome the problem of electrostatic charge accumulation, eliminate the resistance problem caused by static electricity, ensure the smoothness of the entire production process, and then ensure the uniformity of TPU foamed leather.

Among them, the present invention can use a calender to press and stretch the melt to form a TPU film, and can also use a casting machine to flow and stretch the melt to form a TPU film.

Specifically, in step 1, the diisocyanate is one or a mixture of MDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate); the chain expander is one or a mixture of 1,4BG (1,4-butanediol) and EG (ethylene glycol); the polymer diol is one or a mixture of AA/EG (polyethylene adipate), AA/1,4BG (AA/1,4-butanediol polymer diol), PCL (polycaprolactone), PC (polycarbonate), PTMEG (polytetrahydrofuran ether) and PPG (polypropylene glycol).

More specifically, the polyethylene glycol is a non-ionic polyethylene glycol. Compared with anionic polyethylene glycol and cationic polyethylene glycol, non-ionic polyethylene glycol has better reactivity and can react completely in a short time.

More specifically, in step 1, the hydroxyl value of the high molecular weight diol is 20-200, the hydroxyl value of the polyethylene glycol is 30-600, and the resistance value is 1×10 ¹¹ ~9×10 ¹² Ω.

More specifically, in step 1, the following raw materials are also prepared in the filling machine: antioxidant and anti-yellowing agent, and the temperature of the antioxidant and anti-yellowing agent is 85-95° C. Adding antioxidant and anti-yellowing agent can make TPU foam leather have good antioxidant and anti-yellowing properties, that is, improve its physical properties.

More specifically, the antioxidant is a mixture of one or more of 1010 antioxidant, 1076 antioxidant, 1098 antioxidant and 168 antioxidant; the anti-yellowing agent is a mixture of one or more of UV-328, UV-327, UV-P and UV-765.

More specifically, the filling machine includes: a first hopper, a second hopper and a third hopper, the diisocyanate is located in the first hopper, the chain expander is located in the second hopper, the polymer diol, polyethylene glycol, antioxidant and anti-yellowing agent are located in the third hopper, the temperature of the first hopper and the second hopper is 65-75°C, and the temperature of the third hopper is 85-95°C. The raw materials in the three hoppers are poured into the reactive twin-screw extruder for mixing.

More specifically, in step 2, the flow rate of diisocyanate (i.e., the first hopper) is 1-3 kg/min, the flow rate of chain expander (i.e., the second hopper) is 0.2-1 kg/min, and the flow rate of polymer diol, polyethylene glycol, antioxidant and anti-yellowing agent (i.e., the third hopper) is 2-4 kg/min.

Specifically, the reactive twin-screw extruder includes: an initial section, a cooling section, a filter and a material hole. The initial section is connected to the front end of the cooling section, the filter is located at the rear end of the cooling section, and the material hole is located on the side of the cooling section.

In step 2, the following steps are specifically included:

Step 2.1, pouring the raw materials in the pouring machine into the initial section for forced polymerization, the forced polymerization temperature is 200-220°C;

Step 2.2: The raw materials in the initial section are transferred to the cooling section for forced cooling at a temperature of 170-190°C.

Among them, the forced polymerization in step 2.1 is relative to the non-forced polymerization. The traditional non-forced polymerization refers to the polymerization of diisocyanate and chain expander at 120-130°C. Although it can reduce energy consumption, the polymerization process is relatively slow. For the segmented continuous preparation method adopted in the present invention, it is easy to have partial incomplete polymerization. Therefore, the present invention preferably adopts the forced polymerization method.

Among them, since the present invention adopts a high-temperature forced polymerization method, before adding the foaming agent, that is, in step 2.2, the raw materials need to be forcedly cooled to avoid pre-foaming.

As a preferred solution, a mixing head can be set at the upper end of the initial section of the reactive twin-screw extruder. The mixing head has a stirring device. The raw materials are initially mixed through high-speed stirring, and then the raw materials are input into the initial section for mechanical energy forced polymerization, thereby improving the polymerization efficiency.

Specifically, in step 3, the foaming agent is one or more of DIPA (diisopropyl azodicarboxylate), BaAC (barium azodicarboxylate), azoaminobenzene, ADCA (azodicarbonamide), DPT (N,N'-dinitrosopentamethylenetetramine), PTSS (p-toluenesulfonyl semicarbazide), benzenesulfonyl chloride and THT (trihydrazinotriazine).

Specifically, in step 3, calcium carbonate is also added to the reactive twin-screw extruder, and the temperatures of the foaming agent and calcium carbonate are both 170-190° C., forming a melt with a temperature of 170-190° C. Calcium carbonate can fix the foamed pores and make the TPU foamed leather stronger.

More specifically, in step 3, the following steps are specifically included:

Step 3.1, adding a foaming agent and calcium carbonate to the cooling section through the material hole, the temperature of the foaming agent and calcium carbonate are both 170~190℃;

Step 3.2: Filter the raw materials through a filter to form a melt with a temperature of 170-190°C.

Among them, after filtering through the filter, the temperature of the melt is maintained at 170~190℃, and the foaming agent and calcium carbonate are evenly dispersed, showing the best plasticization state.

More specifically, in step 3, the flow rate of the foaming agent is 0.1-1 kg/min, and the flow rate of the calcium carbonate is 0.01-0.2 kg/min.

Specifically, the calender includes: a turbine, a cloth supply device and a laminating device.

In step 4, the melt from the reactive twin-screw extruder is extruded into a turbine for stretching at a temperature of 170-190°C to form a TPU film.

Among them, for general calenders on the market, a 10,000-horsepower machine, a front-stage turbine and a filter are usually arranged upstream of the turbine, and the turbine used in the present invention belongs to the rear-stage turbine. Since the present invention adopts a segmented continuous manufacturing method, the upstream of the rear-stage turbine is directly fed through a filling machine and a reactive twin-screw extruder, so the 10,000-horsepower machine, the front-stage turbine and the filter of the turbine are not needed, which is conducive to reducing energy consumption.

More specifically, in step 4, the thickness of the formed TPU film is 0.05 mm to 0.30 mm, that is, the roller spacing of the turbine is 0.05 mm to 0.30 mm.

In step 5, the turbine inputs the TPU film into the laminating device, and the fabric supply device inputs the fabric into the laminating device. The laminating device laminates the TPU film and the fabric at a laminating temperature of 180-200° C. to form a foamed substrate.

Specifically, the foaming furnace includes: a first zone, a second zone, a third zone, a fourth zone and a fifth zone.

In step 6, the foamed substrate in the calender is fed into the first zone to be softened at a softening temperature of 170-190°C.

In step 7, the following steps are specifically included:

Step 7.1, feeding the foamed substrate softened in the first zone into the second zone, and performing initial foaming on the foamed substrate, the temperature of the initial foaming being 210-220°C;

Step 7.2, inputting the foamed substrate after initial foaming in the second zone into the third zone, and performing a large amount of foaming on the foamed substrate, and the temperature of the large amount of foaming is 220-230°C;

Step 7.3: The foamed substrate after the large-scale foaming in the third zone is input into the fourth zone to fully foam the foamed substrate at a temperature of 230-240°C to form TPU foamed leather.

Foaming the foaming substrate by step-by-step heating is conducive to achieving balanced foaming, thereby making the TPU foamed leather more uniform.

Specifically, the continuous production method further includes the following steps:

Step 8: The TPU foamed leather in the fourth zone is fed into the fifth zone and cooled at a temperature of 150-160°C.

More specifically, the above-mentioned continuous manufacturing method also uses an embossing machine, and the continuous manufacturing method also includes the following steps:

Step 9, embossing the TPU foam leather;

Step 10: Cooling and rolling up the embossed TPU foam leather.

Among them, in step 8, the TPU foam leather is not cooled to room temperature, which is conducive to better subsequent embossing operation.

The technical solution of the present invention is further described below by way of embodiments:

[Example 1]

This embodiment provides a continuous production method of TPU foam leather, which specifically includes the following steps:

The first stage is to prepare the melt:

Step 1. Prepare the following raw materials in a filling machine: MDI, 1,4BG, AA/1,4BG (hydroxyl value is 56), non-ionic polyethylene glycol (hydroxyl value is 54), 1010 antioxidant and UV-328. MDI is in the first hopper at a temperature of 70°C, 1,4BG is in the second hopper at a temperature of 70°C, AA/1,4BG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 are all in the third hopper at a temperature of 90°C.

Step 2.1, pouring the raw materials in the pouring machine into the initial section of the reactive twin-screw extruder for forced polymerization, the flow rate of MDI is 1.26 kg/min, the flow rate of 1,4BG is 0.31 kg/min, the flow rate of AA/EG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 is 3.43 kg/min, and the forced polymerization temperature is 210°C;

Step 2.2, transferring the raw materials in the initial section to the cooling section for forced cooling, the forced cooling temperature is 190°C;

Step 3.1, adding DIPA and calcium carbonate to the cooling section through the material hole, the flow rate of DIPA is 0.15 kg/min, the flow rate of calcium carbonate is 0.1 kg/min, and the temperature of DIPA and calcium carbonate is 180°C;

Step 3.2, filtering the raw materials through a filter to form a melt with a temperature of 180° C.;

The second stage is to make the foam substrate:

Step 4, extruding the melt from the reactive twin-screw extruder to the turbine of the calender for stretching at a stretching temperature of 180° C. to form a TPU film with a thickness of 0.25 mm;

Step 5, the turbine inputs the TPU film to the laminating device, the fabric supply device inputs the non-woven fabric with a thickness of 1 mm to the laminating device, and the laminating device laminates the TPU film and the fabric at a laminating temperature of 190° C. to form a foamed substrate with a thickness of 1.2 mm;

The third stage is to make TPU foam leather:

Step 6: feeding the foamed substrate in the calender into the first zone of the foaming furnace at a line speed of 20 m/min, and softening the foamed substrate at a softening temperature of 190° C.

Step 7.1, feeding the foamed substrate softened in the first zone into the second zone, and performing initial foaming on the foamed substrate, the temperature of the initial foaming being 210° C.;

Step 7.2, inputting the foamed substrate after initial foaming in the second zone into the third zone, and performing bulk foaming on the foamed substrate, wherein the bulk foaming temperature is 220° C.;

Step 7.3, the foamed substrate after the large amount of foaming in the third zone is input into the fourth zone, and the foamed substrate is fully foamed at a temperature of 230° C. to form TPU foamed leather;

Step 8, the TPU foam leather in the fourth zone is fed into the fifth zone, and the TPU foam leather is cooled at a cooling temperature of 150°C. The thickness of the TPU foam leather after shaping is 1.6 mm;

Step 9, embossing the TPU foam leather;

Step 10: Cooling and rolling up the embossed TPU foam leather.

The TPU foam leather sample prepared in this embodiment is shown in Figure 2, and the TPU foam leather has no collapse phenomenon.

[Example 2]

This embodiment provides a continuous production method of TPU foam leather, which specifically includes the following steps:

The first stage is to prepare the melt:

Step 1. Prepare the following raw materials in a filling machine: MDI, 1,4BG, AA/1,4BG (hydroxyl value is 110), non-ionic polyethylene glycol (hydroxyl value is 120), 1010 antioxidant and UV-328. MDI is in the first hopper at a temperature of 70°C, 1,4BG is in the second hopper at a temperature of 70°C, PTMEG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 are all in the third hopper at a temperature of 90°C.

Step 2.1, pouring the raw materials in the pouring machine into the initial section of the reactive twin-screw extruder for forced polymerization, the flow rate of MDI is 1.92 kg/min, the flow rate of 1,4BG is 0.46 kg/min, the flow rate of PTMEG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 is 2.62 kg/min, and the forced polymerization temperature is 210°C;

Step 2.2, transferring the raw materials in the initial section to the cooling section for forced cooling, the forced cooling temperature is 180°C;

Step 3.1, adding ADCA and calcium carbonate to the cooling section through the material hole, the flow rate of ADCA is 0.15 kg/min, the flow rate of calcium carbonate is 0.1 kg/min, and the temperature of ADCA and calcium carbonate is 180°C;

Step 3.2, filtering the raw materials through a filter to form a melt with a temperature of 180° C.;

The second stage is to make the foam substrate:

Step 4, extruding the melt from the reactive twin-screw extruder to the turbine of the calender for stretching at a stretching temperature of 180° C. to form a TPU film with a thickness of 0.2 mm;

Step 5, the turbine inputs the TPU film to the laminating device, the fabric supply device inputs the non-woven fabric with a thickness of 1 mm to the laminating device, and the laminating device laminates the TPU film and the fabric at a laminating temperature of 190° C. to form a foamed substrate with a thickness of 1.15 mm;

The third stage is to make TPU foam leather:

Step 6: feeding the foamed substrate in the calender into the first zone of the foaming furnace at a line speed of 20 m/min, and softening the foamed substrate at a softening temperature of 190° C.

Step 7.1, feeding the foamed substrate softened in the first zone into the second zone, and performing initial foaming on the foamed substrate, the temperature of the initial foaming being 210° C.;

Step 7.2, inputting the foamed substrate after initial foaming in the second zone into the third zone, and performing bulk foaming on the foamed substrate, wherein the bulk foaming temperature is 220° C.;

Step 7.3, the foamed substrate after the large amount of foaming in the third zone is input into the fourth zone, and the foamed substrate is fully foamed at a temperature of 230° C. to form TPU foamed leather;

Step 8, the TPU foam leather in the fourth zone is fed into the fifth zone, and the TPU foam leather is cooled at a cooling temperature of 150°C. The thickness of the TPU foam leather after shaping is 1.45mm;

Step 9, embossing the TPU foam leather;

Step 10: Cooling and rolling up the embossed TPU foam leather.

The TPU foam leather sample prepared in this embodiment is shown in Figure 3, and the TPU foam leather has no collapse phenomenon.

[Example 3]

This embodiment provides a continuous production method of TPU foam leather, which specifically includes the following steps:

The first stage is to prepare the melt:

Step 1. Prepare the following raw materials in a filling machine: MDI, 1,4BG, AA/EG (hydroxyl value is 37), non-ionic polyethylene glycol (hydroxyl value is 40), 1010 antioxidant and UV-328. MDI is in the first hopper at a temperature of 70°C, 1,4BG is in the second hopper at a temperature of 70°C, AA/EG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 are all in the third hopper at a temperature of 90°C.

Step 2.1, pouring the raw materials in the pouring machine into the initial section of the reactive twin-screw extruder for forced polymerization, the flow rate of MDI is 2.37 kg/min, the flow rate of 1,4BG is 0.805 kg/min, the flow rate of AA/EG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 is 1.825 kg/min, and the forced polymerization temperature is 200°C;

Step 2.2, transferring the raw materials in the initial section to the cooling section for forced cooling, the forced cooling temperature is 180°C;

Step 3.1, adding PTSS and calcium carbonate to the cooling section through the material hole, the flow rate of PTSS is 0.7 kg/min, the flow rate of calcium carbonate is 0.1 kg/min, and the temperature of PTSS and calcium carbonate is 170°C;

Step 3.2, filtering the raw materials through a filter to form a melt with a temperature of 170°C;

The second stage is to make the foam substrate:

Step 4, extruding the melt from the reactive twin-screw extruder to the turbine of the calender for stretching at a stretching temperature of 170° C. to form a TPU film with a thickness of 0.15 mm;

Step 5, the turbine inputs the TPU film to the laminating device, the fabric supply device inputs the non-woven fabric with a thickness of 1 mm to the laminating device, and the laminating device laminates the TPU film and the fabric at a laminating temperature of 180° C. to form a foamed substrate with a thickness of 1.1 mm;

The third stage is to make TPU foam leather:

Step 6: feeding the foamed substrate in the calender into the first zone of the foaming furnace at a line speed of 20 m/min, and softening the foamed substrate at a softening temperature of 190° C.

Step 7.1, feeding the foamed substrate softened in the first zone into the second zone, and performing initial foaming on the foamed substrate, the temperature of the initial foaming being 210° C.;

Step 7.2, inputting the foamed substrate after initial foaming in the second zone into the third zone, and performing bulk foaming on the foamed substrate, wherein the bulk foaming temperature is 220° C.;

Step 7.3, the foamed substrate after the large amount of foaming in the third zone is input into the fourth zone, and the foamed substrate is fully foamed at a temperature of 230° C. to form TPU foamed leather;

Step 8, the TPU foam leather in the fourth zone is fed into the fifth zone, and the TPU foam leather is cooled at a cooling temperature of 150°C. The thickness of the TPU foam leather after shaping is 2.1 mm;

Step 9, embossing the TPU foam leather;

Step 10: Cooling and rolling up the embossed TPU foam leather.

The TPU foam leather sample prepared in this embodiment is shown in Figure 4, and the TPU foam leather has no collapse phenomenon.

[Example 4]

This embodiment provides a continuous production method of TPU foam leather, which specifically includes the following steps:

The first stage is to prepare the melt:

Step 1, prepare the following raw materials in a filling machine: MDI, 1,4BG, PCL, non-ionic polyethylene glycol, 1010 antioxidant and UV-328, MDI is located in the first hopper at a temperature of 70°C, 1,4BG is located in the second hopper at a temperature of 70°C, PCL, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 are all located in the third hopper at a temperature of 90°C;

Step 2.1, pouring the raw materials in the pouring machine into the initial section of the reactive twin-screw extruder for forced polymerization, the flow rate of MDI is 1.075 kg/min, the flow rate of 1,4BG is 0.215 kg/min, the flow rate of AA/EG, non-ionic polyethylene glycol, 1010 antioxidant and UV-328 is 3.71 kg/min, and the forced polymerization temperature is 220°C;

Step 2.2, transferring the raw materials in the initial section to the cooling section for forced cooling, the forced cooling temperature is 200°C;

Step 3.1, adding BaAC and calcium carbonate to the cooling section through the material hole, the flow rate of BaAC is 0.15 kg/min, the flow rate of calcium carbonate is 0.1 kg/min, and the temperature of BaAC and calcium carbonate is 190°C;

Step 3.2, filtering the raw materials through a filter screen to form a melt with a temperature of 190° C.;

The second stage is to make the foam substrate:

Step 4, extruding the melt from the reactive twin-screw extruder to the turbine of the calender for stretching at a stretching temperature of 180° C. to form a TPU film with a thickness of 0.2 mm;

Step 5, the turbine inputs the TPU film to the laminating device, the fabric supply device inputs the non-woven fabric with a thickness of 1 mm to the laminating device, and the laminating device laminates the TPU film and the fabric at a laminating temperature of 190° C. to form a foamed substrate with a thickness of 1.15 mm;

The third stage is to make TPU foam leather:

Step 6: feeding the foamed substrate in the calender into the first zone of the foaming furnace at a line speed of 20 m/min, and softening the foamed substrate at a softening temperature of 190° C.

Step 7.1, feeding the foamed substrate softened in the first zone into the second zone, and performing initial foaming on the foamed substrate, the temperature of the initial foaming being 210° C.;

Step 7.2, inputting the foamed substrate after initial foaming in the second zone into the third zone, and performing bulk foaming on the foamed substrate, wherein the bulk foaming temperature is 220° C.;

Step 7.3, the foamed substrate after the large amount of foaming in the third zone is input into the fourth zone, and the foamed substrate is fully foamed at a temperature of 230° C. to form TPU foamed leather;

Step 8, the TPU foam leather in the fourth zone is fed into the fifth zone, and the TPU foam leather is cooled at a cooling temperature of 150°C. The thickness of the TPU foam leather after shaping is 1.35mm;

Step 9, embossing the TPU foam leather;

Step 10: Cooling and rolling up the embossed TPU foam leather.

The TPU foam leather sample prepared in this embodiment is shown in Figure 5, and the TPU foam leather has no collapse phenomenon.

The above embodiments will be tested below:

[Semi-finished product physical property test]

Before the foaming agent and calcium carbonate were added to the semi-finished products of each embodiment, some samples were extracted and cooled naturally, crushed and granulated, and hardness, elongation, tensile strength, 100% modulus and tear strength tests were performed respectively. The test results are as follows:

[Table 1] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Hardness (A/D) 83A 92A 68D 65A Elongation (%) 823 751 402 1022 Tensile strength (kg/cm ² ) 376 403 522 323 100% modulus 55 88 216 twenty one Tear strength (kg/cm ² ) 136 182 289 112

As can be seen from [Table 1], the semi-finished products of each embodiment have good hardness, elongation, tensile strength, 100% modulus and tear strength after cooling. TPU foam leathers with different properties can be produced according to the physical properties of the semi-finished products of different embodiments.

[Environmental performance test]

The finished products of each embodiment were tested for polycyclic aromatic hydrocarbons (PAHs), substances of very high concern (SVHC) and N,N-dimethylformamide (DMF) using a gas chromatography-mass spectrometer. The test results are as follows:

[Table 2] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 PAHs (%) 0 0 0 0 SVHC (%) 0 0 0 0 DMF (%) 0 0 0 0

As can be seen from [Table 2], the contents of polycyclic aromatic hydrocarbons, substances of very high concern and N,N-dimethylformamide in each embodiment are all zero, which meets the environmental protection requirements.

[Resistance test]

The finished products of each embodiment were tested for resistance, and the test results are as follows:

[Table 3] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Resistance (Ω) 6×10 ¹¹ 2×10 ¹² 5×10 ¹² 3×10 ¹¹

It can be seen from [Table 3] that the resistance values of the embodiments are all below 9×10 ¹² Ω, the conductivity is good, the generated charges can be quickly transferred, and no spark phenomenon is caused by charge accumulation, which meets the anti-static requirements.

[Foaming test]

The expansion ratio of the finished product of each embodiment was tested and compared with the expected gas emission of each foaming agent. The test results are as follows:

[Table 4] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Foaming agent DIPA ADCA PTSS Bac Expected gas emission (ml/g) 200~300 200~300 130~180 200~300 Foaming ratio (%) 250 250 700 200

It can be seen from [Table 4] that the foaming ratio of each embodiment is consistent with the expected gas generation amount of each foaming agent, that is: foaming ratio ≥ 100% + minimum value of expected gas generation amount × 40%.

[Peel strength test]

The peeling strength test was conducted on the TPU film and TPU foam leather formed by the semi-finished products of each embodiment, and the sample area of the TPU film and TPU foam leather was ^3cm2 . Specifically, the foaming surface of the TPU film was attached to the PET film, and then the peeling strength of the two was tested; the finished fabric was peeled, and the peeling strength of the TPU film and the non-woven fabric was tested. The test results are as follows:

[Table 5] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 TPU film peeling strength (kg/3cm ² ) 11 12 15 9.2 TPU foam leather peeling strength (kg/3cm ² ) 12 13 16 9.8

It can be seen from [Table 5] that the peel strength of the TPU film of each embodiment is above 6kg/ ^3cm2 , and the peel strength of the TPU foamed leather is above 6kg/ ^3cm2 , which meets the peel strength requirements and has good physical properties.

[Weather resistance test]

The finished products of each embodiment were subjected to salt water spray treatment, and the bending resistance and tear strength before treatment were tested. The salt water spray treatment was as follows: 5% sodium hydroxide was added to deionized water to make salt water, and the finished products of each embodiment were sprayed with the above salt water, and placed in a high and low temperature cycle environment of -20~70℃ for 72 hours, and the single cycle time was 12 hours. The test results are as follows:

[Table 6] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Bending resistance before treatment (10,000 times) 40 30 20 50 Bending resistance after treatment (10,000 times) 35 25 15 50 Tear strength before treatment (kg/cm ² ) 136 182 289 112 Tear strength after treatment (kg/cm ² ) 122 180 251 105

It can be seen from [Table 6] that the TPU foam leather of each embodiment can still withstand more than 100,000 bending times and more than 100kg/ ^cm2 of tear strength after salt water spray treatment, which meets the requirements of bending resistance and tear strength and has good physical properties.

[Hydrolysis resistance test]

The finished products of each embodiment were soaked in salt water to observe the degree of fragmentation and precipitation. Specifically, 10% sodium hydroxide was added to deionized water to make salt water, and the finished products of each embodiment were soaked in the above salt water at a temperature of 25°C for 72 hours. The test results are as follows:

[Table 7] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Degree of fragmentation Low Low Low Low Degree of precipitation Low Low Low Low

It can be seen from [Table 7] that the finished products of each embodiment have low degree of fragmentation and precipitation after immersion and good physical properties.

[Abrasion resistance test]

The finished products of each embodiment were tested for wear resistance using a wear resistance tester, and the test results are as follows:

[Table 8] Test Items Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Wear index T (mg) twenty two 26 14 42

As can be seen from [Table 8], the wear index of the finished products of each embodiment is below 100 mg, which meets the industry requirements and has good physical properties.

The above-mentioned embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structures, features and principles described in the patent application scope of the present invention should be included in the scope of the patent application of the present invention.

In summary, the technical means disclosed in this invention can effectively solve the problems of knowledge and achieve the expected purpose and effect. Moreover, it has not been seen in publications and has not been publicly used before the application, and it has long-term progress. It is indeed an invention as referred to in the Patent Law. Therefore, I have filed an application in accordance with the law and sincerely pray that the Supreme Court will give a detailed review and grant the invention patent. I will be very grateful.

However, the above are only several preferred embodiments of the present invention, and should not be used to limit the scope of implementation of the present invention. In other words, all equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the invention specification should still fall within the scope of the present invention patent.

[The present invention] None

[Figure 1] is a schematic diagram of the production line involved in the present invention; [Figure 2] is a photo of the TPU foamed leather sample prepared in Example 1 of the present invention; [Figure 3] is a photo of the TPU foamed leather sample prepared in Example 2 of the present invention; [Figure 4] is a photo of the TPU foamed leather sample prepared in Example 3 of the present invention; [Figure 5] is a photo of the TPU foamed leather sample prepared in Example 4 of the present invention.

Claims (10)

A continuous production method for TPU foamed leather, characterized in that: the continuous production method comprises the following steps: Step 1, prepare the following raw materials: diisocyanate, chain expander, polymer diol and polyethylene glycol, the temperature of diisocyanate and chain expander is 65~75℃, the temperature of polymer diol and polyethylene glycol is 85~95℃; Step 2, mix the raw materials, the mixing temperature is 170~220℃; Step 3, add foaming agent, the temperature of foaming agent is 170~190℃, and form a melt with a temperature of 170~190℃; Step 4, stretch the melt, the stretching temperature is 170~190℃, and form a TPU film; Step 5: Lay the TPU film and the fabric at a laminating temperature of 180-200°C to form a foaming substrate; Step 6: Soften the foaming substrate at a softening temperature of 170-190°C; Step 7: Foam the foaming substrate at a foaming temperature of 210-240°C to form TPU foamed leather. The continuous production method of TPU foamed leather as described in claim 1, wherein in step 1, the following raw materials are also prepared: an antioxidant and an anti-yellowing agent, and the temperature of the antioxidant and the anti-yellowing agent is 85~95℃. The continuous production method of TPU foam leather as described in claim 2, wherein, in step 1, the diisocyanate is one of MDI and TDI or a mixture of two; the chain expander is one of 1,4BG and EG or a mixture of two; the high molecular diol is one of AA/EG, AA/1,4BG, PCL, PC, PTMEG and PPG; the antioxidant is 1010 The anti-yellowing agent is a mixture of one or more of UV-328, UV-327, UV-P and UV-765; in step 3, the foaming agent is a mixture of one or more of DIPA, BaAC, azoaminobenzene, ADCA, DPT, PTSS, benzenesulfonyl chloride and THT. The continuous production method of TPU foamed leather as described in claim 2, wherein, in step 1, the hydroxyl value of the polymer diol is 20-200, the hydroxyl value of the polyethylene glycol is 30-600, and the resistance value is 1×10 ¹¹ ~9×10 ¹² Ω. The continuous production method of TPU foamed leather as described in claim 2, wherein in step 2, the flow rate of inputting diisocyanate is 1~3kg/min, the flow rate of inputting expander is 0.2~1kg/min, and the flow rate of inputting high molecular diol, polyethylene glycol, antioxidant and anti-yellowing agent is 2~4kg/min. The continuous production method of TPU foam leather as described in claim 1, wherein in step 2, the following steps are included: Step 2.1, forced polymerization of the raw materials, the forced polymerization temperature is 200~220℃; Step 2.2, forced cooling of the raw materials, the forced cooling temperature is 170~190℃. The continuous production method of TPU foamed leather as described in claim 6, wherein in step 3, the following steps are included: Step 3.1, adding a foaming agent and calcium carbonate, the temperature of the foaming agent and calcium carbonate are both 170~190℃; Step 3.2, filtering the raw materials to form a melt with a temperature of 170~190℃. The continuous production method of TPU foamed leather as described in claim 7, wherein in step 7, the following steps are included: Step 7.1, initial foaming of the foaming substrate, the temperature of the initial foaming is 210~220℃; Step 7.2, bulk foaming of the foaming substrate, the temperature of bulk foaming is 220~230℃; Step 7.3, full foaming of the foaming substrate, the temperature of full foaming is 230~240℃, to form TPU foamed leather. The continuous production method of TPU foam leather as described in claim 8, wherein the continuous production method further comprises the following steps: Step 8, cooling the TPU foam leather, the cooling temperature is 150~160℃. The continuous production method of TPU foam leather as described in claim 9, wherein the continuous production method further comprises the following steps: Step 9, embossing the TPU foam leather; Step 10, cooling and winding the embossed TPU foam leather.