Preparation method of PUR hot melt adhesive for shoes

Abstract

The invention discloses a preparation method of a PUR (polyurethane) hot melt adhesive for shoes, which comprises the following steps: putting polyether polyol and thermoplastic resin into a reaction kettle, carrying out vacuum stirring and dissolving under the nitrogen condition of 120-130 DEG C, then adding crystalline polyester polyol, liquid amorphous polyester polyol and solid amorphous polyester polyol into the reaction kettle, carrying out vacuum stirring and dissolving under the nitrogen condition of 120-130 DEG C, and carrying out vacuum stirring and cooling to obtain the PUR hot melt adhesive for shoes. Continuously stirring in vacuum under the nitrogen condition of 120-130 DEG C to remove water until the water content does not exceed 500ppm to obtain a primary mixture, cooling the primary mixture to 80 DEG C, adding a pure isocyanate monomer which is melted or returned to the normal temperature under the nitrogen condition, carrying out vacuum stirring reaction at 80-100 DEG C, testing the content of free NCO during the reaction, and if the content does not meet the requirement, stopping the reaction; and if not, continuing the reaction until the content of free NCO reaches the standard. The prepared PUR hot melt adhesive has good bonding strength, mechanical properties and water resistance, the comprehensive use performance of the PUR hot melt adhesive is improved, and the preparation method of the PUR hot melt adhesive is convenient to operate and control and beneficial to industrial production.

Description

Technical Field

[0001] The invention relates to the field of PUR hot melt adhesive, and in particular to a method for preparing PUR hot melt adhesive for shoes. Background Art

[0002] PUR hot melt adhesive is a reactive polyurethane hot melt adhesive that can be applied under molten conditions, has a certain initial viscosity, and solidifies to produce strong adhesion after reacting with moisture on the surface of the substrate. As an important adhesive material in the shoe industry, PUR hot melt adhesive plays a key role in the bonding process between the sole and the upper with its good bonding strength and weather resistance. It can cure quickly and provide adhesion to ensure the tight combination of the sole and the upper. However, with the progress of society, the performance requirements for PUR hot melt adhesive are getting higher and higher. The existing PUR hot melt adhesive often has the problems of low water resistance and mechanical properties, and its adhesion also needs to be further improved. Therefore, a person skilled in the art provides a method for preparing PUR hot melt adhesive for shoes to solve the problems raised in the above-mentioned background technology. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing a PUR hot melt adhesive for shoes, comprising the following steps:

[0004] Step 1: Put the polyether polyol and thermoplastic resin into a reaction kettle, and dissolve them by vacuum stirring under nitrogen at 120°C-130°C;

[0005] Step 2: adding the crystalline polyester polyol, the liquid non-crystalline polyester polyol and the solid non-crystalline polyester polyol into the reaction kettle, and continuing to remove water by vacuum stirring under nitrogen conditions at 120° C. to 130° C. until the water content does not exceed 500 ppm, to obtain a primary mixture;

[0006] Step 3: Cool the primary mixture to 80°C, then add pure isocyanate monomer that has been melted or warmed to room temperature under nitrogen, and perform vacuum stirring reaction at 80°C-100°C;

[0007] Step 4: During step 3, the free NCO content needs to be tested. If it does not meet the requirements, the reaction is continued until the free NCO content meets the requirements to obtain a secondary mixture;

[0008] Step 5: Under nitrogen conditions, add the organic tin catalyst to the secondary mixture and stir it in vacuum for 10 min-15 min. Then, under nitrogen conditions, add the waterproofing agent and antioxidant to the secondary mixture and stir it in vacuum for 10 min-15 min to obtain PUR hot melt adhesive.

[0009] Preferably, in step 1, the vacuum stirring and dissolving time is 2h-2.5h.

[0010] Preferably: in the step 1, the proportion of the polyether polyol is 20%-30%, and the proportion of the thermoplastic resin is 5%-10%.

[0011] Preferably, in step 2, the stirring and water removal time is 1h-2h.

[0012] Preferably, in the step 2, the proportions of crystalline polyester polyol, liquid non-crystalline polyester polyol and solid non-crystalline polyester polyol are 7%-10%, 5%-8% and 8%-12% respectively.

[0013] Preferably, in step 3, the vacuum stirring reaction time is 2h-3h.

[0014] Preferably, the PUR hot melt adhesive is heated to 110° C., and after all bubbles of the UR hot melt adhesive are exhausted, the hot melt adhesive is continuously extruded into strips through an extruder.

[0015] Preferably, the extruded PUR hot melt adhesive is put into a water tank for cooling and shaping, the hot melt adhesive is immediately shaped when it meets water, and is pulled into a second cooling water tank by a traction machine to be fully cooled.

[0016] Preferably, the PUR hot melt adhesive after cooling and shaping is cut according to specific specifications.

[0017] Technical effects and advantages of the present invention:

[0018] The invention enables the prepared PUR hot melt adhesive to have good bonding strength, mechanical properties and water resistance, improves the comprehensive use performance of the PUR hot melt adhesive, and the preparation method of the PUR hot melt adhesive is convenient to operate and control, and is conducive to industrial production. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0020] Example 1

[0021] In this embodiment, a method for preparing a PUR hot melt adhesive for shoes is provided, comprising the following steps:

[0022] Step 1: Put the polyether polyol and the thermoplastic resin into a reaction kettle, and dissolve them by vacuum stirring under nitrogen at 120°C for 2.5 hours. The proportion of the polyether polyol is 20% and the proportion of the thermoplastic resin is 10%;

[0023] Step 2: Add crystalline polyester polyol, liquid non-crystalline polyester polyol and solid non-crystalline polyester polyol into the reactor, continue to stir and remove water under vacuum under nitrogen conditions at 120°C until the water content does not exceed 500ppm, to obtain a primary mixture, the stirring and dehydration time is 2h, and the proportions of crystalline polyester polyol, liquid non-crystalline polyester polyol and solid non-crystalline polyester polyol are 10%, 5% and 12% respectively;

[0024] Step 3: Cool the primary mixture to 80°C, then add pure isocyanate monomer that has been melted or warmed to room temperature under nitrogen, and perform vacuum stirring reaction at 80°C for 3 hours;

[0025] Step 4: During step 3, the free NCO content needs to be tested. If it does not meet the requirements, the reaction is continued until the free NCO content meets the requirements to obtain a secondary mixture;

[0026] Step 5: Under nitrogen conditions, an organic tin catalyst is added to the secondary mixture, and the mixture is stirred in vacuum for 10 minutes. Then, under nitrogen conditions, a waterproofing agent and an antioxidant are added to the secondary mixture, and the mixture is stirred in vacuum for 15 minutes to obtain a PUR hot melt adhesive.

[0027] Step 6: Heat the PUR hot melt adhesive to 110°C, and after all the bubbles in the UR hot melt adhesive are exhausted, extrude it into strips through an extruder;

[0028] Step 7: The extruded PUR hot melt adhesive enters the water tank for cooling and shaping. The hot melt adhesive immediately sets its shape when it meets water, and enters the second cooling water tank through the traction of the traction machine to be fully cooled;

[0029] Step 8: Cut the cooled and shaped PUR hot melt adhesive into pieces according to specific specifications.

[0030] Example 2

[0031] A method for preparing PUR hot melt adhesive for shoes comprises the following steps:

[0032] Step 1: Put the polyether polyol and the thermoplastic resin into a reaction kettle, and dissolve them by vacuum stirring under nitrogen at 130°C for 2 hours. The proportion of the polyether polyol is 30% and the proportion of the thermoplastic resin is 5%;

[0033] Step 2: Add crystalline polyester polyol, liquid non-crystalline polyester polyol and solid non-crystalline polyester polyol into the reactor, continue to remove water by vacuum stirring under nitrogen at 130°C until the water content does not exceed 500ppm, and obtain a primary mixture. The stirring and removing water time is 1h, and the proportions of crystalline polyester polyol, liquid non-crystalline polyester polyol and solid non-crystalline polyester polyol are 7%, 8% and 8% respectively;

[0034] Step 3: Cool the primary mixture to 80°C, then add pure isocyanate monomer that has been melted or warmed to room temperature under nitrogen, and perform vacuum stirring reaction at 100°C for 2 hours;

[0035] Step 4: During step 3, the free NCO content needs to be tested. If it does not meet the requirements, the reaction is continued until the free NCO content meets the requirements to obtain a secondary mixture;

[0036] Step 5: Under nitrogen conditions, an organic tin catalyst is added to the secondary mixture, and the mixture is stirred in vacuum for 15 minutes. Then, under nitrogen conditions, a waterproofing agent and an antioxidant are added to the secondary mixture, and the mixture is stirred in vacuum for 10 minutes to obtain a PUR hot melt adhesive.

[0037] Step 6: Heat the PUR hot melt adhesive to 110°C, and after all the bubbles in the UR hot melt adhesive are exhausted, extrude it into strips through an extruder;

[0038] Step 7: The extruded PUR hot melt adhesive enters the water tank for cooling and shaping. The hot melt adhesive immediately sets its shape when it meets water, and enters the second cooling water tank through the traction of the traction machine to be fully cooled;

[0039] Step 8: Cut the cooled and shaped PUR hot melt adhesive into pieces according to specific specifications.

[0040] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A method for preparing PUR hot melt adhesive for shoes, characterized in that: The following steps are involved: Step 1: Put the polyether polyol and thermoplastic resin into a reaction kettle, and dissolve them by vacuum stirring under nitrogen at 120°C-130°C; Step 2: adding the crystalline polyester polyol, the liquid non-crystalline polyester polyol and the solid non-crystalline polyester polyol into the reaction kettle, and continuing to remove water by vacuum stirring under nitrogen conditions at 120° C. to 130° C. until the water content does not exceed 500 ppm, to obtain a primary mixture; Step 3: Cool the primary mixture to 80°C, then add pure isocyanate monomer that has been melted or warmed to room temperature under nitrogen, and perform vacuum stirring reaction at 80°C-100°C; Step 4: During step 3, the free NCO content needs to be tested. If it does not meet the requirements, the reaction is continued until the free NCO content meets the requirements to obtain a secondary mixture; Step 5: Under nitrogen conditions, add the organic tin catalyst to the secondary mixture and stir it in vacuum for 10 min-15 min. Then, under nitrogen conditions, add the waterproofing agent and antioxidant to the secondary mixture and stir it in vacuum for 10 min-15 min to obtain PUR hot melt adhesive.

2. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: In the step 1, the vacuum stirring dissolution time is 2h-2.5h.

3. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: In the step 1, the proportion of polyether polyol is 20%-30%, and the proportion of thermoplastic resin is 5%-10%.

4. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: In the step 2, the stirring and water removal time is 1h-2h.

5. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: In the step 2, the proportions of crystalline polyester polyol, liquid non-crystalline polyester polyol and solid non-crystalline polyester polyol are 7%-10%, 5%-8% and 8%-12% respectively.

6. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: In the step 3, the vacuum stirring reaction time is 2h-3h.

7. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: The PUR hot melt adhesive is heated to 110° C., and after all bubbles of the UR hot melt adhesive are exhausted, it is continuously extruded into strips through an extruder.

8. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: The extruded PUR hot melt adhesive enters a water tank for cooling and shaping. The hot melt adhesive is immediately shaped when it meets water, and enters a second cooling water tank through the traction of a traction machine to be fully cooled.

9. The method for preparing a PUR hot melt adhesive for shoes according to claim 1, characterized in that: The PUR hot melt adhesive after cooling and shaping is cut according to specific specifications.