White cardboard production method suitable for hot melt adhesive box pasting

Abstract

The invention discloses a white cardboard production method suitable for hot melt adhesive box pasting, and relates to the technical field of white cardboards, the freeness of fibrils dispersed by a pulper is about 600ml, the fibrils are processed by a mill to reach the required freeness condition, and the LBKP freeness is 400-450; mixing the slurry; performing screening; surfing the Internet; squeezing: squeezing moisture contained in the surface of the wet paper web by using a compression roller, and absorbing the moisture in the paper web by using coarse cotton cloth on the surface of the compression roller; pre-drying; sizing: the sizing amount of the front surface is 2.0-8.0 g / m < 2 >, and the sizing amount of the back surface is 1.0-3.0 g / m Carrying out hard calendaring; coating is conducted, specifically, drying is conducted in an infrared heating mode after each time of coating; the ratio of the back coating latex is 7-10%; soft calendering: enabling the paper web to pass through a steel roller and a rubber covered roller which are arranged up and down and heated; and the coating white cardboard which is completely processed is curled into a paper roll, so that subsequent slitting and storage are facilitated. The box pasting bonding performance of the white cardboard and the hot melt adhesive can be enhanced, so that the packaging quality and the production efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of white cardboard, and in particular to a method for producing white cardboard suitable for hot melt adhesive box pasting. Background Art

[0002] With the rapid development of the packaging industry, hot melt adhesive box gluing has been widely used in the packaging of various products as an environmentally friendly and efficient packaging method. White cardboard, as a commonly used packaging material, has a wide range of applications in the packaging field due to its good printing performance and strength characteristics. However, traditional white cardboard is often difficult to adapt to the special requirements of hot melt adhesive box gluing during the production process, and has problems such as poor adhesive performance and easy debonding. Summary of the invention

[0003] The purpose of the present invention is to address the defects and shortcomings of the prior art and provide a method for producing white cardboard suitable for hot melt adhesive box pasting, which can enhance the bonding performance between white cardboard and hot melt adhesive box pasting to improve packaging quality and production efficiency.

[0004] To achieve the above object, the present invention adopts the following technical scheme: its operation steps are as follows:

[0005] Step 1, refining: the freeness of the original fiber dispersed by the pulper is about 600ml, and it is processed by the mill to the required freeness condition, among which the freeness of NBKP (bleached coniferous pulp by kraft method) is 280-320, and the freeness of LBKP (bleached broadleaf pulp by kraft method) is 400-450;

[0006] Step 2: Mixing pulp: Mix the three layers of raw materials of the surface, core and bottom with wood pulp in different proportions;

[0007] Step 3: Screening: After the slurry is purified, it is screened through a pressure screen to remove the coarse impurities in the slurry system;

[0008] Step 4: Internet: The concentration of the top and bottom webs is controlled at 0.1-0.3%, and the concentration of the core layer is controlled at ≤1.6%; after the water is filtered through the forming net, the dryness reaches 20-22%, and then the three layers of paper are laminated together to enter the next process;

[0009] Step 5: Pressing: Use a press roller to squeeze the moisture on the surface of the wet paper web, and use the felt on the surface of the press roller to absorb the moisture in the paper web;

[0010] Step 6: Pre-drying: The paper web is heated and dried by passing steam through the drying cylinder. The paper web is placed on the surface of the drying cylinder for heat removal, thereby evaporating the moisture in the paper web. After the heating treatment in this section, the dryness of the paper web reaches more than 90%;

[0011] Step 7: Gluing: The raw materials used are mainly enzyme-converted starch, accounting for about 99.5-100%, adding a small amount of sizing agent 0-0.5%, the solid content on the machine is about 10-20%, the preparation viscosity is 60-200cps, and the sizing amount is 2.0-8.0g / m 2 , back side 1.0-3.0g / m 2 ;

[0012] Step 8: Hard calendering: let the paper web pass through heated steel rollers arranged up and down;

[0013] Step 9, coating: After each coating, it is dried by infrared heating; the ratio of back coating latex is 7-10%;

[0014] Step 10: Soft calendering: let the paper web pass through the heated steel roller and rubber-coated roller arranged up and down;

[0015] Step 11: Curling: Curl the fully processed coated white cardboard into a paper roll to facilitate subsequent slitting and storage.

[0016] Preferably, in the step 2, the surface layer is mixed with 10-30% NBKP (bleached coniferous pulp) and 70-90% LBKP (bleached broadleaf pulp); the core layer is mixed with 0-6% LBKP (bleached broadleaf pulp), 57-97% BCTMP (bleached chemical thermal film mechanical pulp) and 5-35% broken paper; the bottom layer is mixed with 10-30% NBKP (bleached coniferous pulp) and 70-90% LBKP (bleached broadleaf pulp).

[0017] Preferably, the step five is performed three times of pressing, the pressure of the first and second pressings is ≤800KN / m, and the pressure of the third pressing is ≤50KN / m. After three pressings, the dryness of the paper web can be increased to 40-45%.

[0018] Preferably, in step eight, the temperature of the vertically arranged heated steel rollers is controlled at 140-180° C., and the pressure is controlled at ≤50 KN / m.

[0019] Preferably, in step nine, the front side is coated three times and the back side is coated once, and the single layer coating amount is controlled at 9.0-20.0 g / m 2 .

[0020] Preferably, in the step 10, the temperature of the heated steel roller and the rubber-coated roller arranged vertically is controlled at 140-180° C., and the pressure is controlled at ≤50 KN / m.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a method for producing white cardboard suitable for hot melt adhesive box pasting, which can enhance the bonding performance between white cardboard and hot melt adhesive box pasting to improve packaging quality and production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a process parameter table of the present invention and the prior art.

[0023] Figure 2 It is an indicator data table of an embodiment of the present invention.

[0024] Figure 3 It is a comparison chart of the box pasting fastness test pictures of Example 1, Example 2, Example 4 and Example 5 in the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. The preferred embodiments in the description are only used as examples, and all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, this specific implementation adopts the following technical solution: its operation steps are as follows:

[0027] Step 1, refining: the freeness of the original fiber dispersed by the pulper is about 600ml, and it is processed by the mill to the required freeness condition, among which the freeness of NBKP (bleached coniferous pulp by kraft method) is 280-320, and the freeness of LBKP (bleached broadleaf pulp by kraft method) is 400-450;

[0028] Step 2, pulp mixing: the three layers of raw materials of the surface, core and bottom are mixed with wood pulp in different proportions, the surface layer is mixed with 10-30% NBKP (bleached coniferous pulp by sulfate process) and 70-90% LBKP (bleached broadleaf pulp by sulfate process); the core layer is mixed with 0-6% LBKP (bleached broadleaf pulp by sulfate process), 57-97% BCTMP (bleached chemical thermal film mechanical pulp) and 5-35% broken paper; the bottom layer is mixed with 10-30% NBKP (bleached coniferous pulp by sulfate process) and 70-90% LBKP (bleached broadleaf pulp by sulfate process);

[0029] Step 3: Screening: To prevent coarse light impurities from having a negative impact on subsequent processing, the slurry is purified and then screened through a pressure screen to remove coarse impurities in the slurry system;

[0030] Step 4: Internet: The concentration of the top and bottom webs is controlled at 0.1-0.3%, and the concentration of the core layer is controlled at ≤1.6%; after the water is filtered through the forming net, the dryness reaches 20-22%, and then the three layers of paper are laminated together to enter the next process;

[0031] Step 5, pressing: the purpose is to further remove the moisture from the paper, by using the pressing roller to squeeze the moisture contained in the surface of the wet paper web, and using the felt cloth on the surface of the pressing roller to absorb the moisture in the paper web; a total of three pressings are performed, the pressure of the first and second pressings is ≤800KN / m, and the pressure of the third pressing is ≤50KN / m. After three pressings, the dryness of the paper web can be increased to 40-45%;

[0032] Step 6: Pre-drying: The purpose is to further remove the moisture contained in the paper web. The paper web is heated and dried by passing steam through the drying cylinder. The paper web is attached to the surface of the drying cylinder for heat removal, thereby evaporating the moisture in the paper web. After the heating treatment in this section, the dryness of the paper web reaches more than 90%;

[0033] Step 7, sizing: The purpose is to apply sizing liquid on the surface of the paper web to form a thin film layer to prevent moisture in the air from penetrating into the paper web. The commonly used raw materials are mainly enzyme-converted starch, accounting for about 99.5-100%, adding a small amount of sizing agent 0-0.5%, the solid content on the machine is about 10-20%, the preparation viscosity is 60-200cps, and the sizing amount is 2.0-8.0g / m 2 , back side 1.0-3.0g / m 2 ;

[0034] Step 8: Hard calendering: The main purpose is to flatten the paper surface and reduce the surface roughness of the paper. The paper web is passed through heated steel rollers arranged up and down. The temperature is controlled at 140-180℃ and the pressure is controlled at ≤50KN / m.

[0035] Step 9: Coating: The main purpose is to evenly coat the paper surface with the coating applied three times on the front and once on the back. The single-layer coating amount is controlled at 9.0-20.0 g / m 2 ; After each coating, it is dried by infrared heating; the ratio of back coating latex is 7-10%;

[0036] Step 10: Soft calendering: The purpose is to finish the paper surface, make the paper smooth and have a higher glossiness; let the paper web pass through the heated steel roller and rubber-coated roller arranged up and down, the temperature is controlled at 140-180℃, and the pressure is controlled at ≤50KN / m;

[0037] Step 11: Curling: Curl the fully processed coated white cardboard into a paper roll to facilitate subsequent slitting and storage.

[0038] Glue fastness test:

[0039] After the paper is die-cut and formed, melted hot melt glue is sprayed on the front of the paper to glue the front and back of the paper together. By tearing the edge of the paper, observe the layering position. If it separates from the hot melt glue bonding position, it means the glue is not strong. If it separates from the inside of the paper, it is qualified. Figure 2 and 3As shown, the higher the grade, the better the pasting fastness (this grade is defined for the convenience of distinguishing fastness and is not a standard method).

[0040] After adopting the above process, the beneficial effects of this specific embodiment are as follows: The present invention provides a method for producing white cardboard suitable for hot melt glue box pasting. By optimizing the production process and raw material formula, the adhesive adaptability and packaging quality of white cardboard are improved. This method not only solves the problems existing in traditional white cardboard when combined with hot melt glue box pasting, ensuring good paste box fastness, but also has the advantages of environmental protection and high efficiency, which is of great significance to promoting the development of the packaging industry.

[0041] For those skilled in the art, they can modify the technical solutions described in the aforementioned embodiments and make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing white cardboard suitable for hot melt adhesive box pasting, characterized in that: Its operation steps are as follows: Step (i), refining: the freeness of the original fibers dispersed by the pulper is about 600 ml, and the freeness is processed by the mill to the required freeness conditions, wherein the freeness of NBKP is 280-320, and the freeness of LBKP is 400-450; Step (ii), mixing pulp: the three layers of raw materials of the surface, core and bottom are mixed with wood pulp in different proportions; Step (iii), screening: After the slurry is purified, it is screened through a pressure screen to remove coarse impurities in the slurry system; Step (IV), web: the web concentration of the top and bottom layers is controlled at 0.1-0.3%, and the core layer concentration is controlled at ≤1.6%; after the water is filtered through the forming wire, the dryness reaches 20-22%, and then the three layers of paper are laminated together to enter the next process; Step (V), pressing: using a press roller to squeeze the moisture contained on the surface of the wet paper web, and using the felt cloth on the surface of the press roller to absorb the moisture in the paper web; Step (six), pre-drying: The paper web is heated and dried by passing steam through the drying cylinder, and the paper web is attached to the surface of the drying cylinder for heat removal, thereby evaporating the water in the paper web. After the heating treatment in this stage, the dryness of the paper web reaches more than 90%; Step (VII), sizing: The raw materials used are mainly enzyme-converted starch accounting for about 99.5-100%, adding a small amount of sizing agent 0-0.5%, the solid content on the machine is about 10-20%, the preparation viscosity is 60-200cps, and the sizing amount is 2.0-8.0g / m 2 , back side 1.0-3.0g / m 2 ; Step (eight), hard calendering: passing the paper web through heated steel rollers arranged one above the other; Step (IX), coating: After each coating, it is dried by infrared heating; the back coating latex ratio is 7-10%; Step (10), soft calendering: let the paper web pass through the heated steel roller and rubber-coated roller arranged up and down; Step (XI), curling: curling the completely processed coated white cardboard into a paper roll to facilitate subsequent slitting and storage.

2. A method for producing white cardboard suitable for hot melt adhesive box gluing according to claim 1, characterized in that: In the step (ii), the surface layer is mixed with NBKP 10-30% and LBKP 70-90%; the core layer is mixed with LBKP 0-6%, BCTMP 57-97% and broken paper 5-35%; and the bottom layer is mixed with NBKP 10-30% and LBKP 70-90%.

3. A method for producing white cardboard suitable for hot melt adhesive box gluing according to claim 1, characterized in that: In the step (V), three pressings are performed, the pressure of the first and second pressings is ≤800KN / m, and the pressure of the third pressing is ≤50KN / m. After three pressings, the dryness of the paper web can be increased to 40-45%.

4. A method for producing white cardboard suitable for hot melt adhesive box gluing according to claim 1, characterized in that: In the step (eight), the temperature of the heated steel rollers arranged up and down is controlled at 140-180° C., and the pressure is controlled at ≤50 KN / m.

5. The method for producing white cardboard suitable for hot melt adhesive box gluing according to claim 1, characterized in that: In the step (IX), the front side is coated three times and the back side is coated once, and the single layer coating amount is controlled at 9.0-20.0 g / m 2 .

6. A method for producing white cardboard suitable for hot melt adhesive box gluing according to claim 1, characterized in that: In the step (10), the temperature of the heated steel roller and the rubber-coated roller arranged up and down is controlled at 140-180° C., and the pressure is controlled at ≤50 KN / m.

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