Curing process of PUR hot melt adhesive for bookbinding

Abstract

The invention discloses a curing process of a PUR hot melt adhesive for bookbinding, and belongs to the technical field of PUR hot melt adhesive processing.The curing process of the PUR hot melt adhesive for bookbinding comprises the specific implementation steps that firstly, the PUR hot melt adhesive is heated and melted; secondly, the PUR hot melt adhesive and book paper sheets are attached; step 3, cooling and solidifying the PUR hot melt adhesive; and step 4, finishing the surface of the cured PUR hot melt adhesive. By controlling the temperature, the humidity and the melting time of the PUR hot melt adhesive in each stage of melting, adhesive injection and curing, the humidifying and curing efficiency of the PUR hot melt adhesive can be effectively guaranteed, meanwhile, the humidifying and curing stability of the PUR hot melt adhesive is guaranteed, the hardness and the bonding force of the finally cured PUR hot melt adhesive are guaranteed, and the use quality of the PUR hot melt adhesive is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of PUR hot melt adhesive processing, and more specifically to a curing process of PUR hot melt adhesive for book binding. Background Art

[0002] Rigid polyurethane hot melt adhesive (PUR) is generally made of terminal isocyanate (-NCO) polyurethane prepolymer as the base material, with tackifying resin, antioxidant, catalyst, filler, etc. During bonding, the adhesive is heated and melted into a fluid and applied. After the two adherends are attached, the adhesive layer cools and condenses to immediately obtain initial bonding strength; then the active -NCO groups in the adhesive layer react with moisture in the air, moisture adsorbed on the surface of the adherend, and active hydrogen groups to produce chemical cross-linking and curing, generating a high molecular polymer with high cohesion, which significantly improves the adhesion and heat resistance.

[0003] Reactive polyurethane hot melt adhesive has the characteristics of hot melt adhesive such as no solvent, high initial adhesion, and rapid positioning during assembly, as well as the properties of reactive adhesive such as water resistance, temperature resistance, creep resistance, moisture resistance and medium resistance. Since its appearance in 1984, it has developed rapidly and has been used more and more widely.

[0004] At present, in the actual use of PUR hot melt adhesive, PUR hot melt adhesive often reacts naturally with the humidity in the air and waits for curing. However, the humidity value in the air is in a floating state, and different humidity values ​​will affect the curing of PER hot melt adhesive. The natural curing method may affect the final curing effect of PUR hot melt adhesive.

[0005] Therefore, in view of this, the existing structure is studied and improved, and a curing process of PUR hot melt adhesive for book binding is provided, in order to achieve a more practical purpose. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a curing process for PUR hot melt adhesive for book binding, which can effectively ensure the efficiency of PUR hot melt adhesive during wet curing, while ensuring the stability of PUR hot melt adhesive during wet curing, ensuring the hardness and adhesion of the finally cured PUR hot melt adhesive, and ensuring the use quality of PUR hot melt adhesive.

[0008] 2. Technical solution

[0009] To solve the above problems, the present invention adopts the following technical solutions.

[0010] A curing process of PUR hot melt adhesive for book binding, the specific implementation steps of the curing process are as follows:

[0011] Step 1: Heating and melting the PUR hot melt adhesive: Take a clean container, heat the container, and control the temperature. Then add a certain amount of PUR hot melt adhesive into the container and wait for the PUR hot melt adhesive to completely melt into a molten state. Continue heating to maintain the PUR hot melt adhesive in a molten state.

[0012] Step 2: Laminating the PUR hot melt adhesive with the book paper: Align the book paper, then clamp the book paper with a fixing clip, place a glue storage tank at the end of the book paper where the PUR hot melt adhesive needs to be cured, insert the fixed end of the book paper into the glue storage tank, and at the same time, inject PUR hot melt adhesive into the glue storage tank;

[0013] Step 3: Cooling and solidification of PUR hot melt adhesive: Detect the humidity in the air and use a hot air blower or humidifier to adjust the humidity until the humidity meets the requirements. Then, wait for the PUR hot melt adhesive to react with moisture to form a polyurethane molecular chain with a rigid structure.

[0014] Step 4: Surface finishing of the cured PUR hot melt adhesive: After the PUR hot melt adhesive is completely cured, take out the book pages and the cured PUR hot melt adhesive, and perform cutting and grinding finishing operations on the PUR hot melt adhesive.

[0015] Furthermore, in the step 1, when heating the container, the temperature is controlled to 160°C.

[0016] Furthermore, in the step 1, when the container is heated, the humidity in the air is detected, and if the humidity in the air is higher than 30%, the humidity is reduced by heating the air.

[0017] Furthermore, in the step 1, the temperature value of maintaining the molten state of the PUR hot melt adhesive is not less than 150°C.

[0018] Furthermore, in step three, the air humidity for the moisture reaction of the PUR hot melt adhesive is required to be 50% to 80%.

[0019] Furthermore, in step 3, the time for waiting for the PUR hot melt adhesive to react with moisture is determined by the temperature, specifically:

[0020] When the temperature value is greater than 25°C, the control waiting time shall not be less than 30 minutes;

[0021] When the temperature value is ≤25℃, the control waiting time shall not be less than 20min.

[0022] Furthermore, in the step 4, the scraps of the PUR hot melt adhesive after cutting and grinding are collected, and then cleaned and dried, and can be subsequently collected and recycled.

[0023] Furthermore, the hardness value of the PUR hot melt adhesive after curing is Shore hardness A73 degrees to D30 degrees.

[0024] 3. Beneficial effects

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] In this scheme, when using PUR hot melt adhesive for book binding operations, the temperature, humidity and melting time of the PUR hot melt adhesive are controlled during the melting stage of the PUR hot melt adhesive, the temperature of the PUR hot melt adhesive is controlled during the injection stage of the PUR hot melt adhesive, and the humidity near the PUR hot melt adhesive is adjusted by a hot air blower or a humidifier during the curing stage of the PUR hot melt adhesive, so that the humidity is 50% to 80% of the wet curing of the PUR hot melt adhesive, which can effectively ensure the efficiency of the PUR hot melt adhesive during wet curing, and at the same time ensure the stability of the PUR hot melt adhesive during wet curing, ensure the hardness and adhesion of the finally cured PUR hot melt adhesive, and ensure the use quality of the PUR hot melt adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the curing process in the present invention; DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] See also Figure 1 , a curing process of PUR hot melt adhesive for book binding, the specific implementation steps of the curing process are as follows:

[0031] Step 1: Heating and melting the PUR hot melt adhesive: Take a clean container, heat the container, and control the temperature. Then add a certain amount of PUR hot melt adhesive into the container and wait for the PUR hot melt adhesive to completely melt into a molten state. Continue heating to maintain the PUR hot melt adhesive in a molten state.

[0032] Specifically, when heating the container, the temperature is controlled to 160° C. to ensure that the PUR hot melt adhesive can be completely melted. At this time, the PUR hot melt adhesive can be filtered to remove impurities therein and ensure the quality of the PUR hot melt adhesive.

[0033] Specifically, when the container is heated, the humidity in the air is detected. If the humidity in the air is higher than 30%, the air is heated to reduce the humidity. By reducing the humidity, the PUR hot melt adhesive can be effectively prevented from chaining with moisture in advance, thereby avoiding the subsequent unstable connection with the book pages.

[0034] Specifically, in step 1, the temperature of the PUR hot melt adhesive in the molten state is maintained at not less than 150° C. In this way, the PUR hot melt adhesive can be ensured not to solidify prematurely, and at the same time, the PUR hot melt adhesive in the molten state and at a higher temperature has better fluidity, which facilitates the implementation of the subsequent glue injection process.

[0035] Step 2: Laminating of PUR hot melt adhesive and book paper pages: Align the book paper, and then use a fixing clip to clamp the book paper pages. When clamping, pay attention to the contact position between the book paper pages and the PUR hot melt adhesive, and use multiple fixing clips to clamp the book paper pages.

[0036] Then, place a glue storage tank at the end of the book paper where the PUR hot melt glue needs to be cured, and insert the fixed end of the book paper into the glue storage tank. At the same time, inject PUR hot melt glue into the glue storage tank. When injecting glue, pay attention to inject slowly to avoid splashing of PUR hot melt glue.

[0037] Step 3: Cooling and solidification of PUR hot melt adhesive: Use a humidity detection sensor to detect the humidity, especially the humidity in the air around the adhesive storage tank. When the humidity is high, use a hot air blower to reduce the humidity. If the humidity is low, use a humidifier to increase the humidity until the humidity meets the requirements.

[0038] Then, wait for the PUR hot melt adhesive to react with moisture to form a polyurethane molecular chain with a rigid structure. During the curing process, the PUR hot melt adhesive forms a cross-linked network structure through moisture curing reaction. This structure enables the PUR hot melt adhesive to maintain a certain flexibility after curing and is not easy to crack.

[0039] Specifically, in step 3, the air humidity for the PUR hot melt adhesive to react with moisture is required to be 50% to 80%. The higher the humidity, the faster the curing speed. In the wet curing stage, the -NCO group in the PUR reacts with the moisture in the air to generate carbamic acid, which is further decomposed into carbon dioxide and amines, and finally urea to form a high molecular polymer with high bonding strength. The humidity is appropriately increased in the production workshop to promote the curing reaction. If the humidity in the air is lower than 50%, it may lead to insufficient reaction and affect the curing effect.

[0040] Specifically, in step 3, the time for waiting for the PUR hot melt adhesive to react with moisture is determined by the temperature, specifically:

[0041] When the temperature value is greater than 25°C, the control waiting time shall not be less than 30 minutes.

[0042] When the temperature value is ≤25℃, the control waiting time shall not be less than 20min.

[0043] The curing effect at different temperatures is different. Ensuring sufficient waiting time is conducive to complete curing.

[0044] Step 4: Surface finishing of the cured PUR hot melt adhesive: After the PUR hot melt adhesive is completely cured, take out the book pages and the cured PUR hot melt adhesive, and perform cutting and grinding finishing operations on the PUR hot melt adhesive.

[0045] Specifically, in step 4, the scraps of the PUR hot melt adhesive after cutting and grinding are collected, and then cleaned and dried, and can be subsequently collected and recycled.

[0046] By collecting and recycling, the consumption cost of PUR hot melt adhesive in the book binding process can be reduced.

[0047] Embodiment 2:

[0048] Based on the above embodiment 1, further description is given.

[0049] The hardness of PUR hot melt adhesive after curing is from Shore A73 to D30.

[0050] Ensure the hardness of PUR hot melt adhesive after curing, prevent it from being damaged and ensure its service life.

[0051] PUR hot melt adhesive can maintain a certain flexibility after curing and is not easy to crack. It can provide good protection when subjected to external impact.

[0052] After curing, PUR hot melt adhesive exhibits excellent water resistance and chemical resistance. During use, it can effectively withstand the erosion of various liquids and chemicals encountered.

[0053] PUR hot melt adhesive has good low volatility and better environmental protection effect.

[0054] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A curing process for PUR hot melt adhesive for book binding, characterized in that: The specific implementation steps of the curing process are as follows: Step 1: Heating and melting the PUR hot melt adhesive: Take a clean container, heat the container, and control the temperature. Then add a certain amount of PUR hot melt adhesive into the container and wait for the PUR hot melt adhesive to completely melt into a molten state. Continue heating to maintain the PUR hot melt adhesive in a molten state. Step 2: Laminating the PUR hot melt adhesive with the book paper: Align the book paper, then clamp the book paper with a fixing clip, place a glue storage tank at the end of the book paper where the PUR hot melt adhesive needs to be cured, insert the fixed end of the book paper into the glue storage tank, and at the same time, inject PUR hot melt adhesive into the glue storage tank; Step 3: Cooling and solidification of PUR hot melt adhesive: Detect the humidity in the air and use a hot air blower or humidifier to adjust the humidity until the humidity meets the requirements. Then, wait for the PUR hot melt adhesive to react with moisture to form a polyurethane molecular chain with a rigid structure. Step 4: Surface finishing of the cured PUR hot melt adhesive: After the PUR hot melt adhesive is completely cured, take out the book pages and the cured PUR hot melt adhesive, and perform cutting and grinding finishing operations on the PUR hot melt adhesive.

2. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: In the step 1, when heating the container, the temperature is controlled to 160°C.

3. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: In the step 1, when the container is heated, the humidity in the air is detected, and if the humidity in the air is higher than 30%, the humidity is reduced by heating the air.

4. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: In the step 1, the temperature of the PUR hot melt adhesive in a molten state is maintained at no less than 150°C.

5. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: In the step 3, the air humidity for the PUR hot melt adhesive to react with moisture is required to be 50% to 80%.

6. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: In step 3, the time for waiting for the PUR hot melt adhesive to react with moisture is determined by the temperature, specifically: When the temperature value is greater than 25°C, the control waiting time shall not be less than 30 minutes; When the temperature value is ≤25℃, the control waiting time shall not be less than 20min.

7. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: In the step 4, the scraps of the PUR hot melt adhesive after cutting and grinding are collected, and then cleaned and dried, and can be collected and recycled later.

8. The curing process of PUR hot melt adhesive for book binding according to claim 1, characterized in that: The hardness of PUR hot melt adhesive after curing is from Shore A73 to D30.

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