Production process and device for composite paper with excellent warping degree

Abstract

The invention discloses a production process and device of composite paper with excellent warping degree, for a process from a PET base film to a PET laser aluminized film part, a chemical layer coating and low-temperature drying process is added after mold pressing so as to prevent the composite paper from warping; the chemical layer is a waterborne polyurethane compound; when the chemical layer is coated, the temperature of the coating box is 40-60 DEG C, so that the laser information weakening caused by the influence of the temperature on the laser layer can be avoided. According to the invention, the process from the PET base film to the PET laser aluminum laminated film is mainly improved, and a chemical layer coating process and a low-temperature drying process are added after mold pressing, so as to prevent the composite paper from warping. The chemical layer is made of a waterborne polyurethane compound, and the drying temperature of the chemical layer is 40-60 DEG C. Under the temperature zone, after the chemical layer is dried, the influence on laser information on the PET mould pressing laser film is small, and the phenomenon that the laser layer is influenced by the temperature to cause'extinction 'is prevented.

Description

Technical Field

[0001] The invention relates to the field of packaging materials, and in particular to a production process and a device for composite paper with excellent warping. Background Art

[0002] At present, light packaging materials such as tobacco, alcohol, and medicine are basically divided into two categories: transfer paper and composite paper. Among them, composite paper has a certain weight in the market due to its advantages of moisture resistance and strong toughness. The production process of composite paper is to use a composite machine to bond the base paper and the PET composite film to produce the finished product. However, due to the tension stretching and oven temperature baking of the PET base film, the film will shrink sharply after bonding, causing the PET base film to rebound. If the base paper is a thin and easy to deform paper, then the base paper will easily warp up. This warping problem is mainly manifested in the longitudinal warping of the paper (along the paper grain direction). Once formed, it is difficult to adjust through the environment or the physical and chemical indicators of the paper. The warping of paper will bring about problems such as uneven printing paper feeding, jamming of the machine, and difficulty in boxing, and there are clear warping standards in the packaging industry. The present invention is to solve the problem of warping of thin and light composite paper.

[0003] At present, the mature technology basically adopts the physical anti-warping method, which uses an anti-warping roller and stretches and scrapes the composite paper in the opposite direction of the paper warping to make it warp in the opposite direction, thereby reducing the warping comprehensively. Although this method is widely used, the paper will still rebound after a period of time after cutting, and it cannot completely solve the warping problem. In addition, according to the thermal shrinkage of the PET base film, a secondary baking method can be used to reduce the rebound of the PET base film, but this method can only be used for PET white film. For PET molded laser film with a laser layer or PET aluminum-plated laser film, high baking temperature is likely to cause the brightness of the laser layer to weaken. When the temperature is low, the degree of shrinkage is limited, and the shrinkage and flatness of the final product cannot be achieved. Summary of the invention

[0004] Based on the above description, the present invention provides a production process and device for composite paper with excellent warping, so as to solve the problem of warping of light and thin composite paper.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A production process for composite paper with excellent warpage, in which a chemical coating and low-temperature drying process are added after molding for the process from PET base film to PET laser aluminized film to prevent the composite paper from warping;

[0007] The chemical layer is a water-based polyurethane compound;

[0008] When coating the chemical layer, the low temperature drying temperature is 40° C.-60° C., which can prevent the laser layer from being affected by temperature and causing the laser information to be weakened.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, in the production process of the composite paper with excellent warpage, after the chemical layer is coated and low-temperature dried, there is a curing step, and the curing time is 12-15 hours.

[0011] Furthermore, the production process of the composite paper with excellent warpage includes the steps of coating imaging resin before molding, and aluminum plating, slitting, compounding and cutting after being placed for curing.

[0012] Furthermore, in the above-mentioned production process of composite paper with excellent warpage, the coating amount of the chemical layer does not exceed 8g / m 2 .

[0013] Furthermore, in the production process of the composite paper with excellent warpage, the shrinkage of the PET base film is determined by measuring the plate spacing on the machine and tracking the plate spacing at the winding position, and comparing the plate spacing difference.

[0014] Furthermore, in the production process of the above-mentioned composite paper with excellent warping, a cursor is engraved on the nickel plate of the molding process. After molding, the PET molded laser film has a fixed cursor at a fixed interval. The shrinkage of the PET base film is judged by comparing the difference between the plate spacing measured on the machine and the plate spacing detected by the electric eye tracking before winding.

[0015] A production device for composite paper with excellent warping, used to manufacture composite paper with excellent warping as described in any of the above items, the water cooling station of the coating machine adopts a multi-roller linkage circulating water cooling device, the multi-roller linkage circulating water cooling device includes a water cooling box, and a plurality of water cooling rollers are connected in the water cooling box.

[0016] Furthermore, in the above-mentioned production device of composite paper with excellent warping, the multi-roller linkage circulating water cooling device also includes a first guide roller and a second guide roller, the first guide roller is connected to the front of the water cooling box, and the second guide roller is located behind the water cooling box.

[0017] Furthermore, in the above-mentioned production device for composite paper with excellent warping, the number of the water-cooling rollers is 4.

[0018] Furthermore, the above-mentioned production device of composite paper with excellent warping also includes a nickel plate and an electric eye detection device for the molding process, the electric eye detection device is connected to the position between the winding seat of the chemical layer coating machine and the adjacent guide roller, and a cursor is engraved on the nickel plate.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0020] The present invention mainly improves the process from PET base film to PET laser aluminum-plated film, and adds a chemical layer coating and low-temperature drying process after molding to prevent the composite paper from warping.

[0021] The chemical layer uses water-based polyurethane compounds, and its drying temperature is 40℃-60℃. In this temperature range, the chemical layer has little effect on the laser information on the PET molded laser film after drying, preventing the laser layer from being affected by temperature and causing "extinction" (weakening of the laser information). When the water-based polyurethane compound is replaced with an oil-based polyurethane compound, its stability is poor and it is difficult to control.

[0022] Compared with the original process which takes 18-24 hours to cure, the curing time of the present invention is greatly shortened to only 12-15 hours. On the one hand, it is because there are multiple water-cooled rollers, and on the other hand, the film coated with the chemical layer shrinks greatly, which saves the tension release time of natural rebound.

[0023] The water cooling station of the coating machine adopts a multi-roller linkage circulating water cooling device, the purpose of which is to quickly cool down after the chemical layer is coated so that the PET base film can shrink more significantly.

[0024] The invention provides a production process for producing light and thin composite paper with excellent warping, thereby solving the warping problem of the composite paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The process flow chart of the prior art composite paper production process is as follows;

[0026] Figure 2 A process flow chart of a production process of composite paper with excellent warpage provided by an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the relevant structure of the water cooling station of the coating machine of the composite paper production device in the prior art;

[0028] Figure 4 A schematic diagram of the relevant structure of a water cooling station of a coating machine of a composite paper production device provided in an embodiment of the present invention;

[0029] Figure 5 The composite paper is produced by the production process of the embodiment of the present invention;

[0030] Figure 6 It is a composite paper made by the original process.

[0031] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0032] 1. First guide roller; 2. Second guide roller; 3. Water-cooled roller; 4. Water-cooled box; 5. Electric eye detection device. DETAILED DESCRIPTION

[0033] In order to facilitate understanding of the present application, the present application will be described more comprehensively below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0035] A production process for composite paper with excellent warpage, in which a chemical coating and low-temperature drying process are added after molding for the process from PET base film to PET laser aluminized film to prevent the composite paper from warping;

[0036] The chemical layer is a water-based polyurethane compound;

[0037] When coating the chemical layer, the low temperature drying temperature is 40° C.-60° C., which can prevent the laser layer from being affected by temperature and causing the laser information to be weakened.

[0038] Based on the above technical solution, the present invention can also be improved as follows.

[0039] Furthermore, in the production process of the composite paper with excellent warpage, after the chemical layer is coated and low-temperature dried, there is a curing step, and the curing time is 12-15 hours.

[0040] Furthermore, the production process of the composite paper with excellent warpage includes the steps of coating imaging resin before molding, and aluminum plating, slitting, compounding and cutting after being placed for curing.

[0041] Furthermore, in the above-mentioned production process of composite paper with excellent warpage, the coating amount of the chemical layer does not exceed 8g / m 2 .

[0042] Furthermore, in the production process of the composite paper with excellent warpage, the shrinkage of the PET base film is determined by measuring the plate spacing on the machine and tracking the plate spacing at the winding position, and comparing the plate spacing difference.

[0043] Furthermore, in the production process of the above-mentioned composite paper with excellent warping, a cursor is engraved on the nickel plate of the molding process. After molding, the PET molded laser film has a fixed cursor at a fixed interval. The shrinkage of the PET base film is judged by comparing the difference between the plate spacing measured on the machine and the plate spacing detected by the electric eye tracking before winding.

[0044] A production device for composite paper with excellent warping, used for manufacturing composite paper with excellent warping as described in any of the above items, wherein the water cooling station of the coating machine adopts a multi-roller linkage circulating water cooling device, and the multi-roller linkage circulating water cooling device comprises a water cooling box 4, and a plurality of water cooling rollers 3 are connected in the water cooling box 4.

[0045] Furthermore, in the above-mentioned production device of composite paper with excellent warping, the multi-roller linkage circulating water cooling device also includes a first guide roller 1 and a second guide roller 2, the first guide roller 1 is connected to the front of the water cooling box 4, and the second guide roller 2 is located behind the water cooling box 4.

[0046] Furthermore, in the above-mentioned production device for composite paper with excellent warping, the number of the water-cooling rollers is 4.

[0047] Furthermore, the above-mentioned production device of composite paper with excellent warping also includes a nickel plate and an electric eye detection device 5 for the molding process, and the electric eye detection device 5 is connected to the position between the winding seat and the second guide roller 2 of the chemical layer coating machine, and a cursor is engraved on the nickel plate.

[0048] Example 1

[0049] The present invention is mainly based on the study of the shrinkage of the PET base film, and solves the technical problem of warping by coating a chemical layer and drying at low temperature. The raw material components of composite paper are mainly base paper and PET base film, and the main factor of paper warping is that the rebound of the PET base film after being stretched causes the base paper to stretch and warp. The PET base film is one of the main materials required for anti-counterfeiting laser laser film, so the present invention mainly optimizes and improves the process from PET base film to PET laser aluminum-plated film (finished film). The process flow chart of the production process of composite paper in the prior art is as follows: Figure 1 As shown, the PET base film is subjected to the process of coating with imaging resin - molding - aluminum plating - placing for curing - slitting - compounding. Studies have shown that both the molding and compounding processes involve high temperature heating and large tension stretching, which results in large deformation of the PET base film, and is the main reason for the warping of the paper after compounding. The present invention adds a step of coating a chemical layer and simultaneously drying at low temperature after the molding laser information process is completed. The chemical layer is composed of Shanghai Bobang Chemical PM-3 water-based polyurethane compound, which can be dried at a relatively low temperature and has good drying shrinkage. The process of the present invention, such as Figure 2 As shown, it includes the following steps: coating imaging resin - molding - coating chemical layer and low temperature drying - placing for curing - aluminum plating - slitting - compounding. Figure 1The process of the prior art adds the process of coating a chemical layer and drying at low temperature. PET molded laser film is a film that produces a laser effect by coating a PET base film with an imaging resin and then molding it. PET laser aluminized film refers to a film that is PET molded laser film that has been subjected to the processes of coating a chemical layer and drying at low temperature, placing it for curing, and aluminizing it.

[0050] In order to select a suitable chemical layer, the present invention selects a water-based polyurethane compound, an oily acrylic compound, and a water-based acrylic compound. When other process conditions are the same, the properties of the composite paper are measured when they are used as chemical layers, as shown in Table 1 below. For the comparison of the chemical layers, it can be seen that:

[0051] Table 1 Properties of different chemical layers and the resulting composite paper

[0052]

[0053] As can be seen from Table 1, waterborne polyurethane compounds have low drying temperature requirements, strong shrinkage, and good film-forming properties, and are the best choice. It should be noted that when waterborne polyurethane compounds are replaced with oily polyurethane compounds, their stability is poor and difficult to control.

[0054] The chemical layer used in the present invention is a water-based polyurethane compound, which is dried by a coating machine. During the drying process, the temperature of the coating oven is set in the range of 40°C-60°C. In this temperature range, the chemical layer has almost no effect on the laser information on the PET base film after low-temperature drying, thereby preventing the laser layer from being affected by temperature and causing "extinction" (weakening of the laser information). During the low-temperature drying process of the chemical layer, it is rapidly cooled by a water-cooled roller, and the chemical layer will shrink as much as possible, thereby affecting the shrinkage of the PET molded laser film, and can restore as much as possible the longitudinal deformation of the PET base film caused by the traction tension and high-temperature hot pressing during the molding process. For the new process (the process of the present invention, such as Figure 2 As shown) and the original process (the process of the prior art, such as Figure 1 As shown in the figure, the new process adds a chemical layer coating and low-temperature drying process, and its effect is comparable to Figure 5 , Figure 6 As shown in Table 2:

[0055] Table 2 Comparison of warpage of composite paper made by original process and new process

[0056] Original process No chemical coating + left to cure Paper warping 1cm or more New Technology Apply chemical layer and dry at low temperature + place to cure The paper is relatively smooth

[0057] from Figure 5 It can be seen that the present invention obtains a relatively smooth composite paper by coating a chemical layer and drying at low temperature. Figure 6 The composite paper has obvious warping; from Table 2, it can be seen that the paper obtained by the original process has a warping of more than 1 cm, while the paper obtained by the process of the present invention is relatively flat.

[0058] The chemical layer of the present invention is a water-based polyurethane compound. The drying temperature effect of the chemical layer is compared as shown in Table 3:

[0059] Table 3 Effect of different drying temperatures on the laser layer

[0060] temperature Laser layer changes 1 40℃-60℃ No obvious changes in the laser layer 2 60℃-75℃ The brightness of the laser layer decreases 3 80℃ and above The brightness of the laser layer is greatly attenuated

[0061] It can be seen from Table 3 that when the drying temperature of the waterborne polyurethane compound chemical layer coated in the present invention is 40° C.-60° C., the laser layer has no obvious change.

[0062] In addition, the original process uses a single roller water cooling device, such as Figure 3 As shown; and the coating machine water cooling station of the present invention adopts a multi-roller linkage circulating water cooling device, such as Figure 4 As shown, when applying the chemical layer, the chemical layer is applied and then dried at low temperature, and then water-cooled..., which is completed on the coating machine at the same time. The purpose is to complete the application of the chemical layer and cool it quickly after low temperature drying to allow the PET base film to shrink together with it. The multi-roller linkage circulating water cooling device can avoid the temperature increase of the circulating water during the long production process, and the linkage cooling time of the single roller for the film is short, resulting in a general cooling effect, and the PET molded laser film rebounds slowly and with a small amplitude. The multi-linked water-cooled roller 3 not only adopts an external circulation water cooling device (that is, there is an external water cooling box, which can effectively control the temperature of the circulating water within the target temperature range), but also multiple sets of water-cooled rollers increase the cooling time and cooling effect of the PET molded laser film, allowing the film to shrink more quickly and stably. The placement and curing time of the new process is greatly reduced. The original process cures for 18-24h, and the new process cures for 12-15h, which saves production time and improves production efficiency. Of course, the number of water-cooled rollers can be 2, 3, 4, 5, 6, etc., and the specific number can be adjusted according to actual conditions. In the present invention, 4 are preferred.

[0063] The plate spacing refers to the unit length of the finished paper in the longitudinal direction (along the paper grain direction). In the chemical layer coating stage, an electric eye detection device 5 is added near the position of the coating machine reel. The original nickel plate involved in the molding process is engraved with a cursor. After molding, the PET molded laser film has a fixed cursor at a fixed interval. The electric eye detection device 5 at the coating reel can track the change of the plate spacing through this electric eye. The shrinkage of the PET base film can be judged by comparing the difference between the plate spacing measured on the machine and the plate spacing detection tracked by the electric eye at the reel. Different brands or thicknesses of base films have different shrinkage amounts due to the amount of chemical layer coating and different product warping standards. Take the 15μm thick PET base film as an example, as shown in Table 4:

[0064] Table 4 Warpage of finished paper after chemical layer coating of different brands of films

[0065] Brand film Chemical layer wet coating amount Reduced spacing Warpage of finished paper A <![CDATA[4g / m 2 ]]> 0.5mm 3mm B <![CDATA[4g / m 2 ]]> 0.65mm 0mm C <![CDATA[4g / m 2 ]]> 0.68mm -1mm

[0066] By collecting and comparing this data, we can know that for base films of different brands, the same coating amount of chemical layer will give inconsistent shrinkage feedback. This can be adjusted by adjusting the coating mesh roller of the chemical layer to change the coating amount of the chemical layer. Generally, the coating amount of the chemical layer should not exceed 8g / m 2 On the one hand, the dryness of the chemical layer is taken into consideration, and on the other hand, the coating amount of the chemical layer is too large or may change the original laser layer information. According to the above operation, the coating amount of the chemical layer can be set or adjusted very accurately to achieve the target shrinkage value of the PET base film. After the above process is completed, the film coated with the chemical layer and dried at low temperature and water-cooled needs to be placed for curing. The purpose is to release the tensile tension of the machine and the curing stability of the coated chemical layer, so that the deformation and rebound of the film can reach a stable state, and the chemical layer and the laser information layer can also be cross-linked and stabilized better. In the subsequent related processes of aluminum plating, slitting, compounding, and cutting, the compounding process needs to use as small a film release traction force as possible (not more than 5kg) to avoid secondary over-stretching of the laser aluminum-plated film. Because the film coated with the chemical layer itself is to increase the shrinkage of the PET molded laser film, if a large tension (for example, a tension greater than 5kg) is used to stretch the film at this time, the effect of increasing the shrinkage will not be achieved, causing the coating of the chemical layer and the low-temperature drying process added by the present invention to prevent warping to lose the anti-warping effect, and only adaptive tension can be used to pull the film to stretch to reduce warping. After reaching the finished product process, the paper warping is detected. According to the warping situation, the shrinkage of the coated PET base film is adjusted by the amount of chemical layer. After comparing and summarizing the shrinkage and warping of the PET base films of different composite papers, the warping problem of different composite papers can be solved.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for producing composite paper with excellent warpage, characterized in that: For the process from PET base film to PET laser aluminized film, a chemical coating layer and low-temperature drying process are added after molding to prevent the composite paper from warping. The chemical layer is a water-based polyurethane compound; When coating the chemical layer, the low temperature drying temperature is 40° C.-60° C., which can prevent the laser layer from being affected by temperature and causing the laser information to be weakened.

2. The process for producing composite paper with excellent warpage according to claim 1, characterized in that: After the chemical layer is coated and low-temperature dried, a curing process is performed, and the curing time is 12-15 hours.

3. The process for producing composite paper with excellent warpage according to claim 2, characterized in that: The process includes coating imaging resin before molding, and aluminum plating, slitting, laminating and cutting after curing.

4. The process for producing composite paper with excellent warpage according to claim 1, characterized in that: The coating amount of the chemical layer does not exceed 8g / m 2 .

5. The process for producing composite paper with excellent warpage according to claim 1, characterized in that: The shrinkage of the PET base film can be determined by measuring the plate distance on the machine and tracking the plate distance at the reeling point, and comparing the plate distance difference.

6. The process for producing composite paper with excellent warpage according to claim 5, characterized in that: A cursor is engraved on the nickel plate of the molding process. After molding, the PET molded laser film has a fixed cursor at a fixed interval. The shrinkage of the PET base film is determined by comparing the difference between the plate spacing measured on the machine and the plate spacing detected by the electric eye tracking before winding.

7. A device for producing composite paper with excellent warpage, characterized in that: For manufacturing a composite paper with excellent warping as described in any one of claims 1 to 6, the water cooling station of the coating machine adopts a multi-roller linkage circulating water cooling device, and the multi-roller linkage circulating water cooling device includes a water cooling box, and a plurality of water cooling rollers are connected in the water cooling box.

8. The device for producing composite paper with excellent warpage according to claim 7, characterized in that: The multi-roller linkage circulating water cooling device also includes a first guide roller and a second guide roller, wherein the first guide roller is connected to the front of the water cooling box, and the second guide roller is located behind the water cooling box.

9. The device for producing composite paper with excellent warpage according to claim 7, characterized in that: The number of the water-cooling rollers is 4.

10. The device for producing composite paper with excellent warpage according to claim 8, characterized in that: It also includes a nickel plate for the molding process and an electric eye detection device, wherein the electric eye detection device is connected between the winding seat of the chemical layer coating machine and the adjacent guide roller, and a cursor is engraved on the nickel plate.

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