Process for the production of cake board paper on a long wire vat size press

Abstract

The application belongs to the technical field of papermaking, and particularly relates to a process for producing cake tray paper by a long net large vat belt gluing machine paper machine. The process for producing cake tray paper by the long net large vat belt gluing machine paper machine has the following production process flow: pulp plate -> chain plate conveying -> pulper -> unloading pool -> refiner -> pulp pool -> pre-pulping pool -> pulping pump -> pressure screen -> headbox -> wire section -> press section -> vat -> gluing machine -> cylinder assembly -> calender -> winding section -> rewinding -> packaging and warehousing; by fully utilizing the vat equipment and surface gluing performance, the problems of poor original paper forming degree, stiffness, easy deformation after processing and difficult peeling are solved under the premise of meeting the breaking degree and transparency, the production cost is greatly reduced, the use requirement of food grade is met, and the process has a broad market prospect.

Description

Technical Field

[0001] This invention belongs to the field of papermaking technology, specifically relating to a process for producing cake tray paper on a paper machine with a long wire, large cylinder, and sizing machine. Background Technology

[0002] As the environment deteriorates and people become increasingly environmentally conscious, environmental protection standards are rising, and the concept of green and environmentally friendly consumption is gaining popularity. Green and environmentally friendly paper packaging is becoming increasingly favored by consumers. Replacing non-biodegradable plastic packaging materials with green and environmentally friendly packaging materials has become a development trend. As a recyclable material, paper food packaging materials inevitably have broad development prospects.

[0003] Cake tray paper is made from paper as the base material, through stamping and processing. The product needs good shaping and formability after mechanical processing, requiring the base paper to have good burst strength, stiffness, smoothness, and transparency. It also needs to have a clean surface and meet food-grade requirements. Therefore, the quality of the base paper directly affects the shaping and use of the cake tray paper. Current cake tray paper production processes mainly use 100% softwood pulp, a high-beating viscous pulping method, and calendering. While this process can guarantee a certain level of burst strength and transparency, the raw material cost is high, beating is difficult, and the equipment requirements are demanding. Furthermore, the paper has poor formability and stiffness, and the processed tray paper is prone to deformation and difficult to peel, failing to meet the requirements of rapid mechanized processing of paper cups and packaging suitable for visual appeal. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a process for producing cake tray paper on a paper machine with a long wire mesh and a large cylinder sizing machine. By fully utilizing the large cylinder equipment and the surface sizing performance, the invention solves the problems of poor formability, poor stiffness, easy deformation after processing, and difficulty in peeling of the base paper while meeting the requirements of burst strength and transparency. It also greatly reduces production costs, meets the requirements for food-grade use, and has broad market prospects.

[0005] The process for producing cake tray paper using a paper machine with a long wire, large cylinder, and sizing machine, as described in this invention, is as follows: Pulp board → Chain conveyor → Pulper → Unloading tank → Refiner → Pulp forming tank → Pre-forming tank → Pulp pump → Pressure screen → Headbox → Wire section → Press section → Large cylinder → Sizing machine → Cylinder assembly → Calender → Winding section → Rewinding → Packaging and warehousing; A detailed process flow diagram is shown below. Figure 1 As shown.

[0006] In the aforementioned adhesive application process, the surface adhesive is composed of the following raw materials in parts by weight:

[0007] Baking silicone oil 20-40 parts;

[0008] 40-60 parts of polyvinyl alcohol;

[0009] 920 portions of water.

[0010] In the pulp board process described above, the pulp board ratio is: 50 wt.% of American bleached sulfate softwood pulp (Alabama) and 50 wt.% of Brazilian bleached sulfate hardwood pulp (Parrot).

[0011] The pulping process described above involves using three DD720 double-disc mills connected in series for pulping. The first mill uses cutting fin-type grinding discs, while the second and third mills use broom-type grinding discs. The freeness is 50-52°SR, and the wet weight is 3.0-4.0g.

[0012] Cationic starch 8-12 kg / ton of slurry is added to the pipe between the slurry forming tank and the pre-slurry forming tank; cationic retention aid 150-250 g / ton of slurry is added to the pipe between the slurry pump and the pressure screen; and anionic retention aid 150-250 g / ton of slurry is added to the pipe between the pressure screen and the headbox.

[0013] In the aforementioned slurry pump process, food-grade wet strength agent and AKD are added at the inlet. The amount of food-grade wet strength agent added is 8-15 kg / ton of slurry, and the amount of AKD added is 15-20 kg / ton of slurry. AKD is preferably a commercially available product from Kemira Company, which has demonstrated strong peeling performance in applications.

[0014] The baking silicone oil is composed of 94 wt.% platinum-catalyzed organosilicon release SYL-OFF. TM 7920 emulsion coating agent and 6 wt.% SYL-OFF TM It is a compound of EM 7975 emulsion catalyst.

[0015] The process for producing cake tray paper using a long-wire paper machine with a large cylinder and sizing machine, wherein the surface adhesive preparation process is as follows:

[0016] 1) Preparation of polyvinyl alcohol:

[0017] After mixing polyvinyl alcohol with water in a polyvinyl alcohol cooking tank, steam is introduced and the temperature is raised to 95-100℃. The temperature is maintained for 20-25 minutes, and the concentration is adjusted to 15-16%. The mixture is then transferred to a surface sizing mixing tank.

[0018] 2) Preparation of baking silicone oil:

[0019] Platinum-catalyzed organosilicon release SYL-OFF TM Add 7920 emulsion coating agent (Dow Chemical) to the silicone oil mixing tank, stir for 5-10 minutes until well mixed, then add SYL-OFF. TMEM 7975 emulsion catalyst (Dow Chemical), stir again for 5-10 minutes, mix evenly, adjust to a concentration of 15-16%, and transfer to the surface slurry mixing tank;

[0020] 3) After all the polyvinyl alcohol and baking silicone oil have been added to the surface adhesive mixing tank according to the formula ratio, add the remaining weight of water to the surface adhesive mixing tank and mix to form a surface adhesive solution with a solid content of 11-13%. Transfer the solution to the surface adhesive storage tank for later use.

[0021] The viscosity of the surface adhesive solution is 15-30 mPa·s, pH is 5-6, and temperature is 65-70℃.

[0022] The paper machine operating parameters are as follows:

[0023] (1) Vehicle speed 300-500m / min;

[0024] (2) The steam pressure of the large cylinder is 500-550 kPa;

[0025] The wet end air temperature of the large cylinder hood is 220-280℃, and the dry end air temperature is 220-280℃.

[0026] (3) Control parameters of the film transfer applicator:

[0027] Metering rod type and pressure:

[0028] Front-side metering bar V30, linear pressure 16-20kN / m;

[0029] Reverse metering bar V30, linear pressure 16-20kN / m;

[0030] Paper pick-up weight with surface sizing agent: 1.5-2.0 g / m² (front side) 2 The reverse side has a content of 1.5-2.0 g / m³. 2 ;

[0031] The paper dryness of the paper entering the film transfer sizing machine is ≥90%, and the paper dryness of the paper exiting the film transfer sizing machine is ≥70%.

[0032] The calender is a dual-pressure zone soft calender. The first pressure zone has a hard roller pressing the front side of the paper (the side with higher paper smoothness), and the second pressure zone has a hard roller pressing the back side of the paper (the side with lower paper smoothness). The first pressure is 50-70 kN / m and the temperature is 120℃; the second pressure is 50-70 kN / m and the temperature is 120℃.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. This invention confirms that a high-speed paper machine equipped with a long wire cylinder and sizing machine can produce qualified cake tray paper.

[0035] 2. This invention uses 50% softwood pulp and hardwood pulp, which can maintain good formability and improve paper stiffness.

[0036] 3. This invention employs a high degree of percussion to ensure the uniformity of the paper sheet and improve its transparency and plasticity.

[0037] 4. The use of baking silicone oil in the surface sizing of this invention can significantly improve the transparency and smoothness of the paper, and most importantly, it enables the paper to peel off easily, allowing end consumers to easily separate the cake from the paper when eating it.

[0038] 5. The present invention incorporates appropriate amounts of PVA in the surface sizing process, which improves paper transparency, stiffness, and peeling effect.

[0039] 6. This invention uses a large-cylinder paper machine for production, which fully utilizes the ironing effect of the large cylinder to improve the smoothness of one side of the paper and increase the peeling effect. Attached Figure Description

[0040] Figure 1 This is a process flow diagram of the production of cake tray paper by the long wire mesh large cylinder paper machine with sizing machine described in this invention;

[0041] Figure 2 This is a flow chart of the preparation process of the surface adhesive described in this invention. Detailed Implementation

[0042] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0043] The raw material procurement information used in the examples and comparative examples is as follows:

[0044] Cationic starch is MYZ-307 high molecular weight cationic starch product of Guangxi Nongken Mingyang Biochemical Group Co., Ltd.

[0045] The cationic retention aid is Solis's PC301L-AP product;

[0046] The food-grade wet strength agent is Solis's 888ULX product;

[0047] The anionic retention aid is Solis' SP8338-AP product.

[0048] Oxidized starch is Zaozhuang Dongfang oxidized corn starch.

[0049] Test method:

[0050] 1. Quantitative standard: GB / T 451.2-2002;

[0051] 4. Tensile strength: GB / T12914-2008;

[0052] 5. Transparency: GB / T2679.1-2020;

[0053] 7. Smoothness: GB / T 456;

[0054] 8. Surface strength: GB-T 22837-2008 Determination of surface strength of paper and paperboard (wax stick method).

[0055] Example 1

[0056] The process for producing cake tray paper using a paper machine with a long wire, large cylinder, and sizing machine, as described in this invention, is as follows: Pulp board → Chain conveyor → Pulper → Unloading tank → Refiner → Pulp forming tank → Pre-forming tank → Pulp pump → Pressure screen → Headbox → Wire section → Press section → Large cylinder → Sizing machine → Cylinder assembly → Calender → Winding section → Rewinding → Packaging and warehousing; A detailed process flow diagram is shown below. Figure 1 As shown.

[0057] In the aforementioned adhesive application process, the surface adhesive is composed of the following raw materials in parts by weight:

[0058] 20 parts baking silicone oil;

[0059] 40 parts of polyvinyl alcohol;

[0060] 920 portions of water.

[0061] In the pulp board process described above, the pulp board ratio is: 50 wt.% of American bleached sulfate softwood pulp (Alabama) and 50 wt.% of Brazilian bleached sulfate hardwood pulp (Parrot).

[0062] The pulping process described above involves using three DD720 double-disc mills connected in series for pulping. The first mill uses cutting fin-type grinding discs, while the second and third mills use broom-type grinding discs. The freeness is 50°SR, and the wet weight is 3.0g.

[0063] Cationic starch 8 kg / ton of slurry is added to the pipe between the slurry forming tank and the pre-slurry forming tank; cationic retention aid 150 g / ton of slurry is added to the pipe between the slurry pump and the pressure screen; and anionic retention aid 150 g / ton of slurry is added to the pipe between the pressure screen and the headbox.

[0064] In the aforementioned slurry pump process, food-grade wet strength agent and AKD are added at the inlet. The amount of food-grade wet strength agent added is 8 kg / ton of slurry, and the amount of AKD added is 15 kg / ton of slurry. AKD is preferably a commercially available product from Kemira Company, which has demonstrated strong peeling performance in applications.

[0065] The baking silicone oil is composed of 94 wt.% platinum-catalyzed organosilicon release SYL-OFF. TM7920 emulsion coating agent and 6 wt.% SYL-OFF TM It is a compound of EM 7975 emulsion catalyst.

[0066] The preparation process of the surface adhesive is as follows:

[0067] 1) Preparation of polyvinyl alcohol:

[0068] Add an appropriate amount of water to polyvinyl alcohol and stir evenly in a polyvinyl alcohol cooking tank. Then, introduce steam and heat to 95°C. Keep the temperature for 20 minutes, adjust the concentration to 15%, and transfer to a surface sizing mixing tank.

[0069] 2) Preparation of baking silicone oil:

[0070] Platinum-catalyzed organosilicon release SYL-OFF TM Add 7920 emulsion coating agent (Dow Chemical) to the silicone oil mixing tank, stir for 5 minutes until well mixed, then add SYL-OFF. TM EM 7975 emulsion catalyst (Dow Chemical), stir again for 5 minutes, mix evenly, adjust to concentration of 15%, and transfer to the surface slurry mixing tank;

[0071] 3) After all the polyvinyl alcohol and baking silicone oil have been added to the surface adhesive mixing tank according to the formula ratio, add the remaining water to the surface adhesive mixing tank and mix to form a surface adhesive solution with a solid content of 11%. Transfer the solution to the surface adhesive storage tank for later use.

[0072] The viscosity of the surface adhesive solution is 15 mPa·s, pH is 5, and temperature is 65℃.

[0073] The paper machine operating parameters are as follows:

[0074] (1) Vehicle speed 300 m / min;

[0075] (2) The steam pressure of the main cylinder is 500 kPa;

[0076] The wet end air temperature of the large cylinder hood is 220℃, and the dry end air temperature is 220℃.

[0077] (3) Control parameters of the film transfer applicator:

[0078] Metering rod type and pressure:

[0079] Front-side metering bar V30, linear pressure 16kN / m;

[0080] Reverse metering bar V30, linear pressure 16kN / m;

[0081] Paper pick-up weight with surface sizing agent: 1.5 g / m² (front side) 2 1.5g / m² on the reverse side 2 ;

[0082] The paper dryness after entering the film transfer sizing machine is 90%, and the paper dryness after exiting the film transfer sizing machine is 70%.

[0083] The calender is a dual-pressure zone soft calender. The first pressure zone has a hard roller pressing the front side of the paper (the side with higher paper smoothness), and the second pressure zone has a hard roller pressing the back side of the paper (the side with lower paper smoothness). The first pressure is 50 kN / m and the temperature is 120℃; the second pressure is 50 kN / m and the temperature is 120℃.

[0084] Example 2

[0085] The process for producing cake tray paper using a paper machine with a long wire, large cylinder, and sizing machine, as described in this invention, is as follows: Pulp board → Chain conveyor → Pulper → Unloading tank → Refiner → Pulp forming tank → Pre-forming tank → Pulp pump → Pressure screen → Headbox → Wire section → Press section → Large cylinder → Sizing machine → Cylinder assembly → Calender → Winding section → Rewinding → Packaging and warehousing; A detailed process flow diagram is shown below. Figure 1 As shown.

[0086] In the aforementioned adhesive application process, the surface adhesive is composed of the following raw materials in parts by weight:

[0087] 40 parts baking silicone oil;

[0088] 60 parts of polyvinyl alcohol;

[0089] 920 portions of water.

[0090] In the pulp board process described above, the pulp board ratio is: 50 wt.% of American bleached sulfate softwood pulp (Alabama) and 50 wt.% of Brazilian bleached sulfate hardwood pulp (Parrot).

[0091] The pulping process described above involves using three DD720 double-disc mills connected in series for pulping. The first mill uses cutting fin-type grinding discs, while the second and third mills use broom-type grinding discs. The freeness is 52°SR, and the wet weight is 4.0g.

[0092] Cationic starch 12 kg / ton of slurry is added to the pipe between the slurry forming tank and the pre-slurry forming tank; cationic retention aid 250 g / ton of slurry is added to the pipe between the slurry pump and the pressure screen; and anionic retention aid 250 g / ton of slurry is added to the pipe between the pressure screen and the headbox.

[0093] In the aforementioned slurry pump process, food-grade wet strength agent and AKD are added at the inlet. The amount of food-grade wet strength agent added is 15 kg / ton of slurry, and the amount of AKD added is 20 kg / ton of slurry. AKD is preferably a commercially available product from Kemira Company, which has demonstrated strong peeling performance in applications.

[0094] The baking silicone oil is composed of 94 wt.% platinum-catalyzed organosilicon release SYL-OFF.TM 7920 emulsion coating agent and 6 wt.% SYL-OFF TM It is a compound of EM 7975 emulsion catalyst.

[0095] The preparation process of the surface adhesive is as follows:

[0096] 1) Preparation of polyvinyl alcohol:

[0097] Add an appropriate amount of water to polyvinyl alcohol and stir evenly in a polyvinyl alcohol cooking tank. Then, introduce steam and heat to 100°C. Keep the temperature for 25 minutes, adjust the concentration to 16%, and transfer it to a surface sizing mixing tank.

[0098] 2) Preparation of baking silicone oil:

[0099] Platinum-catalyzed organosilicon release SYL-OFF TM Add 7920 emulsion coating agent (Dow Chemical) to the silicone oil mixing tank, stir for 10 minutes until well mixed, then add SYL-OFF. TM EM 7975 emulsion catalyst (Dow Chemical), stir again for 10 minutes, mix evenly, adjust to concentration of 16%, and transfer to the surface slurry mixing tank;

[0100] 3) After all the polyvinyl alcohol and baking silicone oil have been added to the surface adhesive mixing tank according to the formula ratio, add the remaining weight of water to the surface adhesive mixing tank and mix to form a surface adhesive solution with a solid content of 13%. Transfer the solution to the surface adhesive storage tank for later use.

[0101] The viscosity of the surface adhesive solution is 30 mPa·s, pH is 6, and temperature is 70℃.

[0102] The paper machine operating parameters are as follows:

[0103] (1) Vehicle speed 500m / min;

[0104] (2) The steam pressure of the large cylinder is 550 kPa;

[0105] The wet end air temperature of the large cylinder hood is 280℃, and the dry end air temperature is 280℃.

[0106] (3) Control parameters of the film transfer applicator:

[0107] Metering rod type and pressure:

[0108] Front-side metering bar V30, linear pressure 20kN / m;

[0109] Reverse metering bar V30, linear pressure 20kN / m;

[0110] Paper pick-up weight with surface sizing agent: 2.0 g / m² (front side) 2 2.0g / m² on the reverse side 2 ;

[0111] The paper dryness after entering the film transfer sizing machine is 92%, and the paper dryness after exiting the film transfer sizing machine is 73%.

[0112] The calender is a dual-pressure zone soft calender. The first pressure zone has a hard roller pressing the front side of the paper (the side with higher paper smoothness), and the second pressure zone has a hard roller pressing the back side of the paper (the side with lower paper smoothness). The first pressure is 70 kN / m and the temperature is 120℃; the second pressure is 70 kN / m and the temperature is 120℃.

[0113] Example 3

[0114] The process for producing cake tray paper using a paper machine with a long wire, large cylinder, and sizing machine, as described in this invention, is as follows: Pulp board → Chain conveyor → Pulper → Unloading tank → Refiner → Pulp forming tank → Pre-forming tank → Pulp pump → Pressure screen → Headbox → Wire section → Press section → Large cylinder → Sizing machine → Cylinder assembly → Calender → Winding section → Rewinding → Packaging and warehousing; A detailed process flow diagram is shown below. Figure 1 As shown.

[0115] In the aforementioned adhesive application process, the surface adhesive is composed of the following raw materials in parts by weight:

[0116] 30 parts baking silicone oil;

[0117] 50 parts of polyvinyl alcohol;

[0118] 920 portions of water.

[0119] In the pulp board process described above, the pulp board ratio is: 50 wt.% of American bleached sulfate softwood pulp (Alabama) and 50 wt.% of Brazilian bleached sulfate hardwood pulp (Parrot).

[0120] The pulping process described above involves using three DD720 double-disc mills connected in series for pulping. The first mill uses cutting fin-type grinding discs, while the second and third mills use broom-type grinding discs. The freeness is 51°SR, and the wet weight is 3.5g.

[0121] 10 kg of cationic starch per ton of slurry is added to the pipe between the slurry forming tank and the pre-slurry forming tank; 200 g of cationic retention aid per ton of slurry is added to the pipe between the slurry pump and the pressure screen; and 200 g of anionic retention aid per ton of slurry is added to the pipe between the pressure screen and the headbox.

[0122] In the aforementioned slurry pump process, food-grade wet strength agent and AKD are added at the inlet. The amount of food-grade wet strength agent added is 12 kg / ton of slurry, and the amount of AKD added is 18 kg / ton of slurry. AKD is preferably a commercially available product from Kemira Company, which has demonstrated strong peeling performance in applications.

[0123] The baking silicone oil is composed of 94 wt.% platinum-catalyzed organosilicon release SYL-OFF. TM 7920 emulsion coating agent and 6 wt.% SYL-OFF TM It is a compound of EM 7975 emulsion catalyst.

[0124] The preparation process of the surface adhesive is as follows:

[0125] 1) Preparation of polyvinyl alcohol:

[0126] Add an appropriate amount of water to polyvinyl alcohol and stir evenly in a polyvinyl alcohol cooking tank. Then, introduce steam and heat to 98°C. Keep the temperature for 23 minutes, adjust the concentration to 15.5%, and transfer it to a surface sizing mixing tank.

[0127] 2) Preparation of baking silicone oil:

[0128] Platinum-catalyzed organosilicon release SYL-OFF TM Add 7920 emulsion coating agent (Dow Chemical) to the silicone oil mixing tank, stir for 8 minutes until well mixed, then add SYL-OFF. TM EM 7975 emulsion catalyst (Dow Chemical), stir again for 8 minutes, mix evenly, adjust to a concentration of 15.5%, and transfer to the surface slurry mixing tank;

[0129] 3) After all the polyvinyl alcohol and baking silicone oil have been added to the surface adhesive mixing tank according to the formula ratio, add the remaining weight of water to the surface adhesive mixing tank and mix to form a surface adhesive solution with a solid content of 12%. Transfer the solution to the surface adhesive storage tank for later use.

[0130] The viscosity of the surface adhesive solution is 25 mPa·s, pH is 5.5, and temperature is 68℃.

[0131] The paper machine operating parameters are as follows:

[0132] (1) Vehicle speed 400 m / min;

[0133] (2) The steam pressure of the large cylinder is 525 kPa;

[0134] The wet end air temperature of the large cylinder hood is 260℃, and the dry end air temperature is 260℃.

[0135] (3) Control parameters of the film transfer applicator:

[0136] Metering rod type and pressure:

[0137] Front-side metering bar V30, linear pressure 18kN / m;

[0138] Reverse metering bar V30, linear pressure 18kN / m;

[0139] Paper pick-up weight with surface sizing agent: 1.8 g / m² (front side) 21.8g / m² on the reverse side 2 ;

[0140] The paper dryness after entering the film transfer sizing machine is 91%, and the paper dryness after exiting the film transfer sizing machine is 72%.

[0141] The calender is a dual-pressure zone soft calender. The first pressure zone has a hard roller pressing the front side of the paper (the side with higher paper smoothness), and the second pressure zone has a hard roller pressing the back side of the paper (the side with lower paper smoothness). The first pressure is 60 kN / m and the temperature is 120℃; the second pressure is 60 kN / m and the temperature is 120℃.

[0142] Comparative Example 1

[0143] Except for changing the large cylinder of the paper machine to the front cylinder, the other process conditions are the same as in Example 3, and cake tray paper of the same weight is produced on a long wire multi-cylinder paper machine.

[0144] Production process of long-wire multi-cylinder paper machine:

[0145] Pulp sheet → Chain conveyor → Pulper → Unloading tank → Refining mill → Pulp forming tank → Pre-filling tank → Pulp pump → Pressure screen → Headbox → Wire section → Press section → Front cylinder → Sizing machine → Rear cylinder → Calender → Winding section → Rewinding → Packaging and warehousing.

[0146] The operating parameters of the long-wire multi-cylinder paper machine are as follows:

[0147] (1) Vehicle speed 400 m / min;

[0148] (2) By controlling the steam pressure of the front cylinder and the rear cylinder, the paper dryness of the inlet film transfer sizing machine is controlled to be 91%, and the paper dryness of the outlet film transfer sizing machine is controlled to be 72%.

[0149] (3) Control parameters of the film transfer applicator:

[0150] Metering rod type and pressure:

[0151] Front-side metering bar V30, linear pressure 18kN / m;

[0152] Reverse metering bar V30, linear pressure 18kN / m;

[0153] Paper pick-up weight with surface sizing agent: 1.8 g / m² (front side) 2 1.8g / m² on the reverse side 2 ;

[0154] The paper dryness after entering the film transfer sizing machine is 91%, and the paper dryness after exiting the film transfer sizing machine is 72%.

[0155] The calender is a dual-pressure zone soft calender. The first pressure zone has a hard roller pressing the front side of the paper (the side with higher paper smoothness), and the second pressure zone has a hard roller pressing the back side of the paper (the side with lower paper smoothness). The first pressure is 60 kN / m and the temperature is 120℃; the second pressure is 60 kN / m and the temperature is 120℃.

[0156] Comparative Example 2

[0157] Other process conditions are the same as in Example 3, and the degree of percussion is 35°SR.

[0158] Comparative Example 3

[0159] Other process conditions are the same as in Example 3, except that the baking silicone oil in the surface coating is removed;

[0160] Comparative Example 4

[0161] Other process conditions are the same as in Example 3, except that the PVA in the surface coating is replaced with the same amount of ordinary oxidized starch.

[0162] At 28g / m 2 For example, cake liners:

[0163]

[0164] Comparative Example 1 uses the same process conditions as Example 3, producing cake tray paper of the same weight on a long-wire multi-cylinder paper machine; however, the smoothness is low, resulting in poor leveling of the surface sizing adhesive, uneven coating of silicone oil and polyvinyl alcohol, and thus the wax stick is below 18#.

[0165] Comparative Example 2 uses the same process conditions as Example 3, but uses a freeness of 35°SR, which is lower than the 50-52°SR of the present invention. This results in lower smoothness, poor fiber bonding, low tensile strength of the paper, lower transparency of the paper than the standard, and low dewaxing strength.

[0166] Comparative Example 3 had the same process conditions as Example 3, except that the baking silicone oil in the surface coating was removed; this resulted in poor peeling effect, low wax rod test values, no silicone oil coverage, low smoothness, and could not meet market needs.

[0167] Comparative Example 4 used the same process conditions as Example 3, except that the PVA in the surface sizing was replaced with the same amount of ordinary oxidized starch; this resulted in low transparency and poor paper appearance, which could not meet market demands.

Claims

1. A process for producing cake tray paper on a paper machine with a long wire mesh, large cylinder, and sizing machine, characterized in that: The production process is as follows: Pulp sheet → Chain conveyor → Pulper → Unloading pool → Refining mill → Pulp forming pool → Pre-filling pool → Pulp pump → Pressure screen → Headbox → Wire section → Press section → Large cylinder → Sizing machine → Cylinder assembly → Calender → Winding section → Rewinding → Packaging and warehousing; In the aforementioned adhesive application process, the surface adhesive is composed of the following raw materials in parts by weight: Baking silicone oil 20-40 parts; 40-60 parts of polyvinyl alcohol; 920 portions of water; The pulping process described herein involves using three DD720 double-disc mills connected in series for pulping. The first mill uses cutting fin-type grinding discs, while the second and third mills use broom-type grinding discs. The freeness is 50-52. ° SR; The baking silicone oil is a compound of 94 wt.% platinum-catalyzed organosilicon release agent SYL-OFFTM7920 emulsion coating agent and 6 wt.% SYLOFFTMEM 7975 emulsion catalyst; The calender described is a dual-pressure zone soft calender. The first pressure zone has a hard roller pressing the front side of the paper, and the second pressure zone has a hard roller pressing the back side of the paper. The first pressure is 50-70 kN / m and the temperature is 120℃; the second pressure is 50-70 kN / m and the temperature is 120℃. In the aforementioned pulp board process, the pulp board ratio is: 50 wt.% bleached sulfate softwood pulp and 50 wt.% bleached sulfate hardwood pulp. Paper pick-up weight with surface sizing agent: 1.5-2.0 g / m² (front side) 2 The reverse side has a content of 1.5-2.0 g / m³. 2 .

2. The process for producing cake tray paper using a long-wire paper machine with a large cylinder and sizing machine according to claim 1, characterized in that, In the aforementioned pulping process, the wet weight is 3.0-4.0g.

3. The process for producing cake tray paper on a paper machine with a long wire mesh, large cylinder, and sizing machine according to claim 1, characterized in that, Cationic starch 8-12 kg / ton of slurry is added to the pipe between the slurry forming tank and the pre-slurry forming tank; cationic retention aid 150-250 g / ton of slurry is added to the pipe between the slurry pump and the pressure screen; and anionic retention aid 150-250 g / ton of slurry is added to the pipe between the pressure screen and the headbox.

4. The process for producing cake tray paper on a paper machine with a long wire mesh, large cylinder, and sizing machine according to claim 1, characterized in that, In the aforementioned slurry pump process, food-grade wet strength agent and AKD are added at its inlet. The amount of food-grade wet strength agent added is 8-15 kg / ton of slurry, and the amount of AKD added is 15-20 kg / ton of slurry.

5. The process for producing cake tray paper on a paper machine with a long wire mesh, large cylinder, and sizing machine according to claim 1, characterized in that, The preparation process of the surface adhesive is as follows: 1) Preparation of polyvinyl alcohol: After mixing polyvinyl alcohol with water in a polyvinyl alcohol cooking tank, steam is introduced and the temperature is raised to 95-100℃. The temperature is maintained for 20-25 minutes, and the concentration is adjusted to 15-16%. The mixture is then transferred to a surface sizing mixing tank. 2) Preparation of baking silicone oil: Add the platinum-catalyzed organosilicon release emulsion coating agent SYL-OFFTM7920 to the silicone oil mixing tank, stir for 5-10 minutes until it is evenly mixed, then add the SYL-OFFTMEM 7975 emulsion catalyst, stir again for 5-10 minutes until it is evenly mixed, adjust the concentration to 15-16%, and transfer it to the surface adhesive mixing tank. 3) After all the polyvinyl alcohol and baking silicone oil have been added to the surface adhesive mixing tank according to the formula ratio, add the remaining weight of water to the surface adhesive mixing tank and mix to form a surface adhesive solution with a solid content of 11-13%. Transfer the solution to the surface adhesive storage tank for later use.

6. The process for producing cake tray paper on a long-wire paper machine with a large cylinder and sizing machine according to claim 5, characterized in that, The viscosity of the surface adhesive solution is 15-30 mPa·s, pH is 5-6, and temperature is 65-70℃.

7. The process for producing cake tray paper on a paper machine with a long wire mesh, large cylinder, and sizing machine according to claim 1, characterized in that, The paper machine operating parameters are: (1) Vehicle speed 300-500m / min; (2) The air pressure of the large cylinder is 500-550 kPa; The wet end air temperature of the large cylinder hood is 220-280℃, and the dry end air temperature is 220-280℃. (3) Control parameters of the film transfer applicator: Metering rod type and pressure: Front-side metering bar V30, linear pressure 16-20kN / m; Reverse metering bar V30, linear pressure 16-20kN / m; The paper dryness of the paper entering the film transfer sizing machine is ≥90%, and the paper dryness of the paper exiting the film transfer sizing machine is ≥70%.

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