Preparation method of waterproof and oil-proof base paper for coated paper

Abstract

The application discloses a preparation method of waterproof and oil-proof base paper for coated paper, and belongs to the technical field of coated paper. The base paper raw material comprises pulp and pulp preparation additives. The pulp preparation additives comprise retention aids, filter aids, in-pulp sizing agents, in-pulp reinforcing agents, system process additives and fluorescence eliminating agents. The in-pulp sizing agents comprise rosin size and aluminum sulfate. The rosin size is anionic. The aluminum sulfate is added to a batching pool, and the rosin size is added to a flow feeding position. The application can quickly and stably control the paper fluorescence value to be less than or equal to 0.1%, and can meet the safety of food paper containers. The paper edge penetration stability is stably controlled to be less than or equal to 3 mm (10 min in 95 DEG C hot water), and the water resistance and stability of subsequent processing into a drinking cup, a face bowl and the like are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coated paper, in particular to a preparation method of a waterproof and oil-proof base paper for coated paperboard. BACKGROUND

[0002] The existing waterproof and oil-proof base paper for coated paperboard mainly refers to a kind of paper made of bleached, semi-bleached or unbleached chemical pulp by high beating degree treatment, including a kind of paper produced by adding waterproof and oil-proof agents in pulp or coating on the surface, which can resist water and oil penetration and absorption.

[0003] However, the existing waterproof and oil-proof base paper for coated paperboard has the following problems: the prepared base paper has high fluorescence value, and many waste products are generated during production, causing waste and high cost.

[0004] Through analysis, the main reasons for the above problems are as follows: when producing the waterproof and oil-proof coated paperboard, the paper with fluorescent whitening agent is usually produced first, then the system is washed to remove dust, fluorescent substances and other impurities, and then the production is continued. However, the residual fluorescent substances in the system cannot be completely removed by manual cleaning, resulting in long-time fluorescence value exceeding the standard (standard ≤0.2%) when producing the waterproof and oil-proof coated paperboard, and many waste products are generated, causing waste. In addition, the amount of fluorescent remover used for washing the car is large, which increases the cost. In addition, when producing the waterproof and oil-proof coated paperboard, it is difficult to control the edge penetration of the finished paper (standard: edge penetration ≤5mm, 10 minutes in 95-degree hot water), and the amount of chemical added is large, which also causes many waste products and waste. In order to solve the problem of difficult edge penetration control, rosin size (acid sizing) is usually used for sizing, but when used, the amount of rosin size added may be too high, the wet part system is too bright, and the sizing is difficult, which makes the edge penetration control of the finished paper more difficult. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a preparation method of a waterproof and oil-proof base paper for coated paperboard, which realizes the following purposes:

[0006] (1) The fluorescence value of the finished paper is quickly and stably controlled to be less than or equal to 0.1%, which meets the safety of food paper containers;

[0007] (2) The edge penetration of the finished paper is stably controlled to be less than or equal to 3mm (10 minutes in 95-degree hot water), which improves the water resistance of the subsequent processing into a cup, a bowl and the like, and stability.

[0008] To solve the above technical problems, the present application adopts the following technical solutions:

[0009] A raw material of a waterproof and oil-proof base paper for coated paperboard, comprising pulp and pulp preparation aid;

[0010] The mass ratio of the slurry to the sizing aid is 8-9:0.65-0.75;

[0011] The slurry comprises a top layer slurry, a backing layer slurry, a core layer slurry, and a bottom layer slurry; wherein the mass ratio of the top layer slurry, the backing layer slurry, the core layer slurry, and the bottom layer slurry is 40-44:25-30:76-106:34-42;

[0012] The base paper for the waterproof and oil-proof coated paperboard is a composite of a top layer, a backing layer, a core layer, and a bottom layer; when the composite is formed, the backing layer is first combined with the core layer, then combined with the top layer, and finally combined with the bottom layer;

[0013] The top layer slurry is a combination of bleached broadleaf wood pulp and bleached coniferous wood pulp;

[0014] Preferably, the top layer slurry is 40-60% bleached broadleaf wood pulp + 40-60% bleached coniferous wood pulp;

[0015] The bleached coniferous wood pulp contains no fluorescent substances and has a dustiness of ≤2.5 mm 2 / m 2 ;

[0016] Under the condition of a freeness of (300±15) CSF, the strength index of the bleached coniferous wood pulp requires the following: a tensile index ≥80.0 N.m / g, according to the standard ISO 1924-2; a burst index ≥8.0 KPa.m 2 / g, according to the standard ISO 2758; a folding number ≥700 times, according to the standard ISO 5626; a brightness ≥88.0%, according to the standard ISO 3688;

[0017] The bleached broadleaf wood pulp contains no fluorescent substances and has a dustiness of ≤2.5 mm 2 / m 2 ;

[0018] Under the condition of a freeness of (300±15) CSF, the strength index of the bleached broadleaf wood pulp requires the following: a tensile index ≥50.0 N.m / g, according to the standard ISO 1924-2; a burst index ≥5.0 KPa.m 2 / g, according to the standard ISO 2758; a folding number ≥40 times, according to the standard ISO 5626; a brightness ≥88.0%, according to the standard ISO 3688;

[0019] The backing layer slurry is a combination of bleached coniferous wood pulp and chemi-mechanical pulp;

[0020] Preferably, the backing layer slurry is 15-30% bleached coniferous wood pulp + 70-85% chemi-mechanical pulp;

[0021] The raw material of the chemi-mechanical pulp is one or a mixture of more than one of poplar, acacia, and eucalyptus wood.

[0022] Preferably, the raw material of the chemi-mechanical pulp is: (0%-50%) poplar + (0%-50%) acacia + (0%-50%) eucalyptus;

[0023] The bleached coniferous pulp has no fluorescent substance, and the dustiness is ≤2.5mm2 / m2 2 2 The chemi-mechanical pulp has no fluorescent substance, a freeness of 300CSF, a brightness of 75 degrees, a bulkiness of >2.0cm3 / g, a tensile index of >30N·m / g, a fiber bundle content of <0.10%, and a pH value of 6.0-8.0; 3

[0024] The beating degree of the bleached coniferous pulp is increased to above 50°SR, and the brightness of the chemi-mechanical pulp is required to be above 75 degrees;

[0025] The core layer pulp is bleached coniferous pulp (NBKP) + chemi-mechanical pulp (TMP pulp) + broke paper or chemi-mechanical pulp + broke paper;

[0026] Preferably, the core layer pulp is 8-12% bleached coniferous pulp (NBKP) + 65-75% chemi-mechanical pulp (TMP pulp) + 15-25% broke paper;

[0027] The raw material of the chemi-mechanical pulp is one or more of poplar, acacia, and eucalyptus mixed;

[0028] Preferably, the raw material of the chemi-mechanical pulp is: (0%-50%) poplar + (0%-50%) acacia + (0%-50%) eucalyptus;

[0029] The broke paper is defibrated, screened, and milled by a broke paper treatment system to obtain the pulp;

[0030] The bleached coniferous pulp has no fluorescent substance, and the dustiness is ≤2.5mm2 / m2; the chemi-mechanical pulp has no fluorescent substance, a freeness of 300CSF, a brightness of 75 degrees, a bulkiness of >2.0cm3 / g, a tensile index of >30N·m / g, a fiber bundle content of <0.10%, and a pH value of 6.0-8.0;

[0031] The beating degree of the bleached coniferous pulp is increased to above 50°SR;

[0032] The bottom layer pulp is bleached broadleaf pulp + bleached coniferous pulp;

[0033] Preferably, the bottom layer pulp is 40-60% bleached broadleaf pulp + 40-60% bleached coniferous pulp;

[0034] The bleached coniferous pulp has no fluorescent substance, and the dustiness is ≤2.5mm2 / m2 2 2 ​​​​

[0035] The bleached softwood pulp has the following strength index requirements under the condition of freeness (300±15) CSF: tensile index ≥ 80.0 N.m / g, execution standard ISO 1924-2; burst index ≥ 8.0 KPa.m / g, execution standard ISO 2758; folding number ≥ 700 times, execution standard ISO 5626; brightness ≥ 88.0%, execution standard ISO 3688; 2 / g, execution standard ISO 2758; folding number ≥ 40 times, execution standard ISO 5626; brightness ≥ 88.0%, execution standard ISO 3688;

[0036] The bleached hardwood pulp has no fluorescence and dust degree ≤ 2.5 mm 2 / m 2

[0037] The bleached hardwood pulp has the following strength index requirements under the condition of freeness (300±15) CSF: tensile index ≥ 50 N.m / g, execution standard ISO 1924-2; burst index ≥ 5.0 KPa.m 2 / g, execution standard ISO 2758; folding number ≥ 40 times, execution standard ISO 5626; brightness ≥ 88.0%, execution standard ISO 3688;

[0038] The pulp preparation aid includes a retention aid, a drainage aid, an internal sizing agent, an internal strengthening agent, a system process aid, and a fluorescence eliminating agent;

[0039] The retention aid is a polyacrylamide (PAM) dry powder retention aid, the PAM dry powder retention aid is white particles, solid content ≥ 88 (oven drying method), viscosity (1%, 25°C) ≥ 550 (Brookfield LVDV-II viscometer), and PH (0.3% aqueous solution, 25°C) is 3.0-6.0 (PHS-3C type pH meter);

[0040] The drainage aid includes an organic microparticle drainage aid and a polyacrylamide (PAM) liquid drainage aid;

[0041] The organic microparticle drainage aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, and the model is V602, viscosity (0.5% aqueous solution, S62 / 5, 20°C) ≥ 500 (Brookfield LVDV-II viscometer), and PH (0.5% aqueous solution, 20°C) is 7.0-9.5 (PHS-3C type pH meter);

[0042] The polyacrylamide (PAM) liquid drainage aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, and the model is VL7035, viscosity (1%, 20°C, S62 / 5) mPa·s ≥ 700 (Brookfield viscometer), and PH (0.1%, 20°C) is 3.0-7.0 (PHS-3C type pH meter);

[0043] The internal sizing agent includes rosin glue and aluminum sulfate;

[0044] The rosin size is anionic, white or light yellow emulsion, solid content is 34-36% (oven drying method); viscosity mpa·s (25℃, S61 / 100) ≤50 (Brookfield LVDV-II viscometer); PH (25℃) is 2.0-4.0 (PHS-3C type pH meter);

[0045] The aluminum sulfate is white or light yellow crystal, flaky; PH (1% aqueous solution 25℃) ≥3.0 (PHS-3C type pH meter); di-aluminum oxide content ≥15.8%, water insoluble ≤0.1%; iron ≤0.005%; the execution standard is HG / T 2225-2010;

[0046] The pulp internal reinforcing agent includes raw starch, cationic starch, dry strength agent, wet strength agent;

[0047] The dry strength agent is colorless transparent to slightly white viscous aqueous solution, the manufacturer is Japan starlight, the model is SK101, the solid content is 20% (oven drying method); viscosity (25℃) 5000-15000 mpa·s (Brookfield LVDV-II viscometer); pH (25℃) is 3-5 (PHS-3C type pH meter);

[0048] The wet strength agent manufacturer is Shandong Tiancheng Chemical, model is PAE-TC;

[0049] The system process aid includes defoaming agent, bactericide, system purifier, broken paper fixing agent;

[0050] The defoaming agent is a combination of alcohol type defoaming agent and ether type defoaming agent, wherein the mass ratio of alcohol type defoaming agent and ether type defoaming agent is 0.7-1.3:1.5-2.5;

[0051] The alcohol type defoaming agent and ether type defoaming agent manufacturers are Jining Nantian Agricultural Science, alcohol type defoaming agent model is 8210, ether type defoaming agent model is 526.

[0052] The alcohol type defoaming agent is milky white to off-white emulsion, PH value (original solution, 25℃) is 5.5-8.0 (PHS-3C type pH meter); specific gravity (25℃) is 0.94-1.0 (mass volume method); viscosity (25℃, S62 / 50) ≤1500 (Brookfield LVDV-II viscometer);

[0053] The ether type defoaming agent is brown oily liquid, specific gravity (25℃) is 0.94-1.0 (mass volume method); viscosity (25℃, S62 / 50) ≤700 (Brookfield LVDV-II viscometer); PH (1% aqueous solution) is 2-6 (PHS-3C type pH meter);

[0054] The bactericide includes a composition of a reaction-prepared bactericide and a preservative bactericide, wherein the mass ratio of the reaction-prepared bactericide and the preservative bactericide is 0.7-1.3:0.7-1.3;

[0055] The reaction-prepared bactericide includes a hypochlorous acid and ammonium sulfate reaction-type bactericide, wherein the mass ratio of the hypochlorous acid and ammonium sulfate reaction-type bactericide is 2.5-3.5:1; the preservative bactericide is a hypochlorous acid and ammonium bromide reaction-type bactericide, wherein the mass ratio of the hypochlorous acid and ammonium bromide reaction-type bactericide is 2.5-3.5:1;

[0056] The manufacturer of the hypochlorous acid and ammonium bromide reaction-type bactericide is Nantian Agricultural Science, wherein the model of the hypochlorous acid reaction-type bactericide is 9510, and the model of the ammonium bromide reaction-type bactericide is 9300.

[0057] The system purifier includes a deposit control agent, the manufacturer of which is Fumi, and the model is TEP-E, which is a white emulsion liquid, the PH (20℃) is 5.0-8.0 (PHS-3C type PH meter), and the viscosity (S61 / 20, 20℃) is ≤30 (Bolife LVDV-II viscometer);

[0058] The broke fixing agent is a light yellow to yellow viscous liquid, the manufacturer of which is Fumi, and the model is FC702, the viscosity (20℃, S62 / 10) is ≥150 (Bolife LVDV-II viscometer), the PH (20℃) is 3.5-6.5 (PHS-3C type PH meter), and the specific gravity (20℃) is 0.95-1.20 (mass-volume method);

[0059] The dosage of the retention aid is: 0.06% for the top layer sizing material, 0.06% for the lining layer sizing material, 0.06% for the core layer sizing material, and 0.06% for the bottom layer sizing material;

[0060] The dosage of the filter aid is: 0.03% for the organic microparticle filter aid for the top layer sizing material, the lining layer sizing material, the core layer sizing material, and the bottom layer sizing material; and 0.05% for the polyacrylamide (PAM) liquid filter aid for the core layer sizing material;

[0061] The dosage of the sizing agent in the pulp is: 2.5% for the rosin sizing agent for the top layer sizing material, 3% for the rosin sizing agent for the lining layer sizing material, 3% for the rosin sizing agent for the core layer sizing material, and 2.5% for the rosin sizing agent for the bottom layer sizing material; and 0.8% for the aluminum sulfate for the top layer sizing material, 1.5% for the aluminum sulfate for the lining layer sizing material, 1.5% for the aluminum sulfate for the core layer sizing material, and 0.8% for the aluminum sulfate for the bottom layer sizing material;

[0062] The amount of the internal strengthening agent is: raw starch: 0.2-0.8% for surface layer sizing material, 0.2-0.8% for core layer sizing material, 0.2-0.8% for bottom layer sizing material; cationic starch: 0.2-0.8% for surface layer sizing material, 0.4-1% for lining layer sizing material, 0.4-1% for core layer sizing material, 0.2-0.8% for bottom layer sizing material; dry strength agent: 2-4% for core layer sizing material; wet strength agent: 0.2-1.2% for surface layer sizing material, 0.5-1.5% for lining layer sizing material, 0.5-1.5% for core layer sizing material, 0.2-1.2% for bottom layer sizing material;

[0063] The amount of the system process aid is: defoaming agent: 0.01-0.08% for surface layer sizing material, 0.03-0.09% for lining layer sizing material, 0.03-0.09% for core layer sizing material, 0.01-0.08% for bottom layer sizing material; bactericide: 0.01-0.05% for surface layer sizing material, 0.02-0.06% for lining layer sizing material, 0.02-0.06% for core layer sizing material, 0.01-0.05% for bottom layer sizing material; system purifier: 0.01-0.03% for surface layer sizing material, 0.01-0.05% for lining layer sizing material, 0.01-0.05% for core layer sizing material, 0.01-0.03% for bottom layer sizing material; broke fixing agent: 0.01-0.05% for core layer sizing material;

[0064] The adding point of the aluminum sulfate is the ingredient pool, and the adding point of the rosin size is the flow sending position;

[0065] The raw starch is used as the interlayer spraying for the surface layer, the core layer and the bottom layer;

[0066] The cationic starch and the wet strength agent are added in the pulp; the cationic starch is added at the inlet of the pre-pulping pool pump; the dry strength agent is added at the outlet of the pre-pulping pool pump; and the wet strength agent is added at the inlet of the ingredient pool pump;

[0067] The model of the fluorescence eliminator is TAVA-706, which is a yellow liquid with positive ion, pH is 3.5-6, and is a polyimidazoline salt type fluorescence eliminator;

[0068] The fluorescence eliminator has two adding points, one is used for intermittent adding in the needle wood pulp pulper and the broad leaf wood pulp pulper, and the adding amount is 0.5%, after detecting that the fluorescence value of the pulp is less than or equal to 0.1%, the amount is reduced to 0.2%; the other adding point is the pre-beating pool of the mixed broke paper, and the adding amount is 0.1%, during the adding, the liquid level of each pulp tower and water tower is kept at 60%-70%.

[0069] A preparation method of a waterproof and oil-proof base paper for coated paper, comprising: beating, sizing, flow sending, web forming, pre-drying;

[0070] The beating process is: pulping - pulp storage tower - high consistency sand removal - double disc mill - post-beating pool;

[0071] After beating, the freeness of NBKP bleached softwood pulp and LBKP bleached hardwood pulp is 325 mL, and the beating degree is 38°SR; the freeness of BCTMP chemi-mechanical pulp is 280 mL, and the beating degree is 42°SR; the freeness of bleached softwood pulp (used for the lining and core layers) is 210 mL, and the beating degree is 50°SR;

[0072] The pulp mixing is the same for the lining, core, and bottom layers, and the process is as follows: post-beating tank-mixing tank-pulping tank (pulp mixing is performed in the pulping tank)-paper machine flow system.

[0073] According to the process ratio of each layer of pulp, the mixing of various pulp amounts is controlled, and after sufficient mixing, the pulp is fed into the pulping tank and then into the paper machine flow system and then into the headbox of the paper machine for spraying and forming.

[0074] The flow system is as follows: pulping tank-sand remover-deaerator-pulping pump-pre-screen-pulse attenuation tank-headbox.

[0075] According to the process design and the running speed requirement, the appropriate wire formation consistency and the headbox spraying speed are set.

[0076] The wire formation is as follows: the pulp of the face, lining, core, and bottom layers is uniformly and stably sprayed onto the forming wire through the headbox, respectively, and the pulp is transferred forward with the forming wire, and is gradually dewatered through the water scraping plate, low vacuum box, and high vacuum box at the bottom of the forming wire. The core layer is provided with a top wire, and the pulp is dewatered through the gap between the top and bottom wires. In addition, the pulp is gradually dewatered through the water scraping plate, low vacuum box, and high vacuum box at the bottom of the forming wire. Finally, the pulp is dewatered to a consistency of 0.4-0.8% for the face layer, 0.4-0.8% for the lining layer, 0.5-1.3% for the core layer, and 0.4-0.8% for the bottom layer.

[0077] The dryness of the paper sheet before the four layers are compounded is controlled to be in the range of 10%-14%, and the dryness of the paper sheet after the four layers are compounded is controlled to be in the range of 20%-24%. During the compounding, the lining layer is first compounded with the core layer, then with the face layer, and finally with the bottom layer. The compounding is performed by a vacuum compounding roll, and the vacuum degree of the compounding roll can be adjusted. After the compounding, a subsequent pressing step is performed.

[0078] The pressing is as follows: the paper sheet is pressed by three straight-through shoe presses to further remove the water in the wet paper web transferred from the wire section, and the dryness of the paper sheet is continuously improved. Three shoe presses are used, and the pressure is set in the range of 800-1250 kN / m. The dryness of the paper sheet after the pressing is in the range of 48%-52%.

[0079] The front drying is as follows: the paper sheet is dried in the drying section, and the water content of the paper sheet after the front drying is controlled to be in the range of 6%-12%, and the waterproof and oil-proof base paper for the coated paper is obtained.

[0080] Compared with the prior art, the present application has the following advantages:

[0081] (1) The waterproof and oil-proof coated paperboard raw paper prepared by the present application has stable and controllable fluorescence, a fluorescence value of ≤0.1%, reduced downgrading caused by excessive fluorescence, stable product quality, and improved safety, environmental protection, and recyclability of the paper through control of the fluorescence value, thereby achieving good social, economic, and environmental benefits.

[0082] (2) The waterproof and oil-proof coated paperboard raw paper prepared by the present application has stable and controlled paper edge penetration of ≤3 mm (10 min in hot water at 95°C), meets the requirements of subsequent paper secondary processing, improves the end customer experience, meets the water resistance requirements of the paper, especially the cross-section of the secondary processed paper, which is the weakest part of waterproofing and is most prone to water absorption, swelling, and paper formation damage, and through control of the edge penetration, the yield can be effectively improved, thereby achieving good economic benefits.

[0083] (3) In the prior art, in order to improve the sizing effect, a large amount of aluminum sulfate and rosin size is used, and the system pH value is low (3.5-4.5), and the papermaking environment is acidic, which has a great impact on the stable papermaking of a high-speed paper machine with a speed of more than 1000 m, the wet end system of the paper machine has large foam, and through optimization of the rosin size addition point and use of anionic rosin size, the sizing effect can be improved, the amount of rosin size and aluminum sulfate can be reduced, the pH value can be controlled to 5.5-6, thereby improving the running environment of the paper machine, stabilizing the operation of the paper machine, and stabilizing the edge penetration control of the finished paper. DETAILED DESCRIPTION

[0084] The preferred embodiments of the present application are described below, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0085] Embodiment 1

[0086] The present embodiment provides a raw material for a waterproof and oil-proof coated paperboard raw paper, which comprises pulp and pulp preparation aids.

[0087] The mass ratio of the pulp to the pulp preparation aid is 8:0.7.

[0088] The pulp comprises surface layer pulp, lining layer pulp, core layer pulp, and bottom layer pulp, and the mass ratio of the surface layer pulp, the lining layer pulp, the core layer pulp, and the bottom layer pulp is 40:30:96:38.

[0089] The preparation method of the waterproof and oil-proof coated paperboard raw paper comprises compounding the surface layer pulp, the lining layer pulp, the core layer pulp, and the bottom layer pulp, and in the compounding, the lining layer is first compounded with the core layer, then compounded with the surface layer, and finally compounded with the bottom layer.

[0090] The wood pulp used in the surface layer pulp, the backing layer pulp, the core layer pulp and the bottom layer pulp is virgin wood pulp fiber, free of fluorescent substances, clean, environmentally friendly and safe.

[0091] The surface layer pulp is a combination of bleached broadleaf wood pulp and bleached coniferous wood pulp, wherein the mass ratio of the bleached broadleaf wood pulp to the bleached coniferous wood pulp is 40:60.

[0092] The bleached coniferous pulp is free of fluorescent substances and has a dust content of ≤2.5 mm 2 / m 2 .

[0093] Under the condition of a freeness of (300±15) CSF, the bleached coniferous wood pulp has the following strength indexes: a tensile index ≥80.0 N.m / g, an execution standard ISO 1924-2; a burst index ≥8.0 KPa.m 2 / g, an execution standard ISO 2758; a folding number ≥700 times, an execution standard ISO 5626; a brightness ≥88.0%, an execution standard ISO 3688.

[0094] The bleached broadleaf wood pulp is free of fluorescent substances and has a dust content of ≤2.5 mm 2 / m 2 .

[0095] Under the condition of a freeness of (300±15) CSF, the bleached broadleaf wood pulp has the following strength indexes: a tensile index ≥50.0 N.m / g, an execution standard ISO 1924-2; a burst index ≥5.0 KPa.m 2 / g, an execution standard ISO 2758; a folding number ≥40 times, an execution standard ISO 5626; a brightness ≥88.0%, an execution standard ISO 3688.

[0096] The backing layer pulp is a combination of bleached coniferous wood pulp and chemi-mechanical pulp, specifically 15% bleached coniferous wood pulp + 85% chemi-mechanical pulp.

[0097] The raw material of the chemi-mechanical pulp is a combination of poplar wood, acacia wood and eucalyptus wood, specifically 20% poplar wood + 50% acacia wood + 30% eucalyptus wood.

[0098] The bleached coniferous wood pulp is free of fluorescent substances and has a dust content of ≤2.5 mm 2 / m 2 .

[0099] The chemi-mechanical pulp is free of fluorescent substances, has a freeness of 300 CSF, a brightness of 75 degrees, a bulkiness of >2.0 cm 3 / g, a tensile index of >30 N.m / g, a fiber bundle content of <0.10%, and a pH value of 6.0-8.0.

[0100] The beating degree of the bleached softwood pulp is above 50°SR, and the brightness of the chemi-mechanical pulp is above 75°;

[0101] The core layer pulp is a combination of bleached softwood pulp (NBKP), chemi-mechanical pulp (TMP pulp) and broke paper, specifically 8% bleached softwood pulp (NBKP) + 70% chemi-mechanical pulp (TMP pulp) + 22% broke paper;

[0102] The raw material of the chemi-mechanical pulp is a combination of poplar, acacia and eucalyptus, specifically 20% poplar + 50% acacia + 30% eucalyptus;

[0103] The pulp of the broke paper is obtained after the broke paper is defibrated, screened and milled by a broke paper treatment system;

[0104] The bleached softwood pulp contains no fluorescent substance and has a dust degree of ≤2.5mm2 / m2; the chemi-mechanical pulp contains no fluorescent substance, has a freeness of 300CSF, a brightness of 75 degrees, a bulkiness of >2.0 cm3 / g, a tensile index of >30N·m / g, a fiber bundle content of <0.10%, and a pH value of 6.0-8.0;

[0105] The beating degree of the bleached softwood pulp is above 50°SR;

[0106] The bottom layer pulp is a combination of bleached hardwood pulp and bleached softwood pulp; the mass ratio of the bleached hardwood pulp to the bleached softwood pulp is 50:50;

[0107] The bleached softwood pulp contains no fluorescent substance and has a dust degree of ≤2.5mm 2 / m 2 ;

[0108] Under the condition of a freeness of (300±15) CSF, the strength indexes of the bleached softwood pulp are as follows: a tensile index ≥80.0N·m / g, an execution standard ISO1924-2; a burst index ≥8.0KPa·m 2 / g, an execution standard ISO2758; a folding number ≥700 times, an execution standard ISO5626; a brightness ≥88.0%, an execution standard ISO3688;

[0109] The bleached hardwood pulp contains no fluorescent substance and has a dust degree of ≤2.5mm 2 / m 2

[0110] Under the condition of a freeness of (300±15) CSF, the strength indexes of the bleached hardwood pulp are as follows: a tensile index ≥50N·m / g, an execution standard ISO1924-2; a burst index ≥5.0KPa·m 2 / g, execution standard ISO 2758; folding times ≥40 times, execution standard ISO 5626; brightness ≥88.0%, execution standard ISO 3688.

[0111] The pulp mixing aid includes a retention aid, a filter aid, an internal sizing agent, an internal strengthening agent, a system process aid, and a fluorescent eliminating agent.

[0112] The retention aid is a polyacrylamide (PAM) dry powder retention aid, the PAM dry powder retention aid is white particles, solid content ≥88 (oven drying method), viscosity (1%, 25°C) ≥550 (Brookfield LVDV-II viscometer), and PH (0.3% aqueous solution, 25°C) is 3.0-6.0 (PHS-3C type pH meter).

[0113] The filter aid includes an organic particulate filter aid and a polyacrylamide (PAM) liquid filter aid.

[0114] The organic particulate filter aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, and the model is V602, viscosity (0.5% aqueous solution, S62 / 5, 20°C) ≥500 (Brookfield LVDV-II viscometer), and PH (0.5% aqueous solution, 20°C) is 7.0-9.5 (PHS-3C type pH meter).

[0115] The polyacrylamide (PAM) liquid filter aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, and the model is VL7035, viscosity (1%, 20°C, S62 / 5) mPa·s ≥700 (Brookfield viscometer), and PH (0.1%, 20°C) is 3.0-7.0 (PHS-3C type pH meter).

[0116] The internal sizing agent includes rosin gum and aluminum sulfate.

[0117] The rosin gum is anionic, white or light yellow emulsion, solid content is 34.5% (oven drying method), viscosity mpa·s (25°C, S61 / 100) ≤50 (Brookfield LVDV-II viscometer), and PH (25°C) is 2.0-4.0 (PHS-3C type pH meter).

[0118] The aluminum sulfate is white or light yellow crystal, flaky, PH (1% aqueous solution 25°C) ≥3.0 (PHS-3C type pH meter), aluminum trioxide content ≥15.8%, water insoluble substance ≤0.1%, and iron ≤0.005%, and the execution standard is HG / T2225-2010.

[0119] The internal strengthening agent includes raw starch, cationic starch, dry strength agent, and wet strength agent.

[0120] The dry strength agent is colorless transparent to slightly white viscous aqueous solution, the manufacturer is Japan Starlight, the model is SK101, the solid content is 20% (oven drying method); viscosity (25 DEG C) 5000-15000 mpa.s (Bo Li Fei LVDV-II viscometer); pH (25 DEG C) is 3-5 (PHS-3C type pH meter);

[0121] The wet strength agent is produced by Shandong Tiancheng Chemical, and the model is PAE-TC.

[0122] The system process aid includes defoaming agent, bactericide, system purifier, paper loss fixing agent.

[0123] The defoaming agent is a combination of alcohol defoaming agent and ether defoaming agent, wherein the mass ratio of alcohol defoaming agent and ether defoaming agent is 0.9:1.1.

[0124] The alcohol defoaming agent and ether defoaming agent are produced by Jining Nantian Agricultural Science, the alcohol defoaming agent is model 8210, and the ether defoaming agent is model 526.

[0125] The alcohol defoaming agent is milky white to off-white emulsion, PH value (original solution, 25 DEG C) is 5.5-8.0 (PHS-3C type pH meter); specific gravity (25 DEG C) is 0.94-1.0 (mass volume method); viscosity (25 DEG C, S62 / 50) is less than or equal to 1500 (Bo Li Fei LVDV-II viscometer).

[0126] The ether defoaming agent is brown oily liquid, specific gravity (25 DEG C) is 0.94-1.0 (mass volume method); viscosity (25 DEG C, S62 / 50) is less than or equal to 700 (Bo Li Fei LVDV-II viscometer); PH (1% aqueous solution) is 2-6 (PHS-3C type pH meter);

[0127] The bactericide includes a combination of on-site reaction preparation type bactericide and preservative bactericidal type bactericide, wherein the mass ratio of reaction preparation type bactericide and preservative bactericidal type bactericide is 0.9:1.1.

[0128] The reaction preparation type bactericide includes hypochlorous acid and ammonium sulfate reaction type bactericide, wherein the mass ratio of hypochlorous acid and ammonium sulfate reaction type bactericide is 2.8:1; the preservative bactericidal type bactericide is hypochlorous acid and ammonium bromide reaction type bactericide, and the mass ratio of hypochlorous acid and ammonium bromide reaction type bactericide is 2.8:1.

[0129] The production factory of the hypochlorous acid and ammonium bromide reaction type bactericide is Nantian Agricultural Science, wherein the model of hypochlorous acid reaction type bactericide is 9510, and the model of ammonium bromide reaction type bactericide is 9300.

[0130] The system purifier includes a deposit control agent, the manufacturer is Fumiao, the model is TEP-E, Jiangsu is a white emulsion liquid, PH (20℃) is 5.0-8.0 (PHS-3C type PH meter); Viscosity (S61 / 20, 20℃) ≤30 (Bo Li Fei LVDV-II viscometer);

[0131] The broke paper fixing agent is a light yellow to yellow viscous liquid, the manufacturer is Fumiao, the model is FC702, viscosity (20℃, S62 / 10) ≥150 (Bo Li Fei LVDV-II viscometer); PH (20℃) is 3.5-6.5 (PHS-3C type PH meter); Specific gravity (20℃) is 0.95-1.20 (mass volume method);

[0132] The dosage of the retention aid is (mass fraction of slurry): 0.06% for the surface layer, 0.06% for the lining layer, 0.06% for the core layer, and 0.06% for the bottom layer;

[0133] The dosage of the filter aid is (mass fraction of slurry): 0.03% for the surface layer, 0.03% for the lining layer, 0.03% for the core layer, and 0.03% for the bottom layer; 0.05% for the core layer of the polyacrylamide (PAM) liquid filter aid;

[0134] The dosage of the internal sizing agent is (mass fraction of slurry): 2.5% for the surface layer, 3% for the lining layer, 3% for the core layer, and 2.5% for the bottom layer; 0.8% for the surface layer, 1.5% for the lining layer, 1.5% for the core layer, and 0.8% for the bottom layer of the aluminum sulfate;

[0135] The dosage of the internal strengthening agent is (mass fraction of slurry): 0.2% for the surface layer, 0.5% for the core layer, and 0.6% for the bottom layer; 0.8% for the surface layer, 1% for the lining layer, 1% for the core layer, and 0.8% for the bottom layer of the cationic starch; 2% for the core layer of the dry strength agent; 0.8% for the surface layer, 1.2% for the lining layer, 1.2% for the core layer, and 0.8% for the bottom layer of the wet strength agent;

[0136] The dosage of the system process aid is (mass fraction of slurry): 0.02% for the surface layer, 0.05% for the lining layer, 0.05% for the core layer, and 0.02% for the bottom layer; 0.02% for the surface layer, 0.04% for the lining layer, 0.04% for the core layer, and 0.05% for the bottom layer of the bactericide; 0.02% for the surface layer, 0.03% for the lining layer, 0.03% for the core layer, and 0.03% for the bottom layer of the system purifier; 0.03% for the core layer of the broke paper fixing agent;

[0137] In the use of the internal sizing agent, the dosing point of the internal sizing agent is optimized, the conventional aluminum sulfate dosing point and the rosin sizing dosing point are at the inlet of the pulp pump, and the interval distance is too close, the aluminum ions are not fully combined with the fibers before the rosin sizing is added, the sizing effect is affected, and the rosin sizing amount is too high; in the embodiment, the aluminum sulfate dosing point is changed from the dilute pulp to the thick pulp, to the ingredient pool, the aluminum ions are fully combined with the fibers, and then the rosin sizing is reacted at the flow sending position, the sizing effect is improved, and the chemical amount is greatly reduced;

[0138] In order to improve the sizing effect, a large amount of cationic additives is added to the system, including retention aid, filter aid, rosin sizing, aluminum sulfate, cationic starch and dry strength agent, the white water charge of the system is positive, the conductivity is high, the wet end system is disordered, the system retention rate is low, and the sizing is difficult, by optimizing the rosin sizing dosing point, combining with the running condition of the paper machine, using anionic rosin sizing, neutralizing the excess cation in the system, reducing the system conductivity, improving the sizing efficiency, improving the charge environment of the wet end, and reducing the chemical amount;

[0139] The raw starch is used as an interlayer spray for a surface layer, a core layer and a bottom layer;

[0140] The cationic starch and the wet strength agent are added in the pulp; specifically, the cationic starch is added at the inlet of the pre-pulping pool pump, the dry strength agent is added at the outlet of the pre-pulping pool pump, and the wet strength agent is added at the inlet of the ingredient pool pump;

[0141] The fluorescent eliminator is a yellow liquid with positive charge, with a pH of 3.5-6, and is a polyimidazoline salt type fluorescent eliminator;

[0142] The elimination mechanism of the fluorescent eliminator is that the polyimidazoline salt group is actively cracked, and after the triazine amino group of the whitening agent is neutralized, carboxyl and carbonyl compounds are generated, which have a fluorescence quenching effect, the molecules of fluorescent substances and the molecules of the eliminator react to generate coordination compounds that do not emit light by themselves, thereby eliminating the whitening agent (mainly styrene triazine derivative), and eliminating the ability of the whitening agent to absorb ultraviolet light in the 335-365nm wavelength range of sunlight;

[0143] The fluorescent eliminator has two dosing points, one is for intermittent addition in the needle wood pulp pulper and the hardwood pulp pulper, and the addition amount is 0.5%, after detecting that the pulp has a fluorescence value of ≤0.1%, the amount is reduced to 0.2%; the other is added to the pre-pulping pool of the mixed broke paper, and the addition amount is 0.1%, the liquid level of each pulp tower and water tower is kept at 60%-70% during the addition period, and is stably controlled, and fluctuation is strictly prohibited.

[0144] Example 2

[0145] The embodiment provides a raw material for a waterproof and oil-proof coated card paper, which comprises pulp and pulp preparation aids;

[0146] The mass ratio of the slurry to the sizing aid is 8:0.7;

[0147] The slurry comprises a surface layer slurry, a backing layer slurry, a core layer slurry and a bottom layer slurry; wherein the mass ratio of the surface layer slurry, the backing layer slurry, the core layer slurry and the bottom layer slurry is 38:27:103:36;

[0148] The preparation method of the waterproof and oil-proof base paper for coated paper comprises the steps of: compounding the surface layer slurry, the backing layer slurry, the core layer slurry and the bottom layer slurry, wherein the backing layer and the core layer are compounded first, then the surface layer is compounded, and finally the bottom layer is compounded;

[0149] The wood pulp used in the surface layer slurry, the backing layer slurry, the core layer slurry and the bottom layer slurry is virgin wood pulp fiber, which is free of fluorescent substances, clean, environmentally friendly and safe;

[0150] The surface layer slurry is a combination of bleached broadleaf wood pulp and bleached coniferous wood pulp, wherein the mass ratio of the bleached broadleaf wood pulp to the bleached coniferous wood pulp is 43:57;

[0151] The bleached coniferous wood pulp is free of fluorescent substances, and the dust content is ≤2.5mm 2 / m 2 ;

[0152] Under the condition of a freeness of (300±15) CSF, the strength index of the bleached coniferous wood pulp requires the following: a tensile index ≥80.0 N.m / g, an execution standard ISO1924-2; a burst index ≥8.0 KPa.m 2 / g, an execution standard ISO2758; a folding number ≥700 times, an execution standard ISO5626; a brightness ≥88.0%, an execution standard ISO3688;

[0153] The bleached broadleaf wood pulp is free of fluorescent substances, and the dust content is ≤2.5mm 2 / m 2 ;

[0154] Under the condition of a freeness of (300±15) CSF, the strength index of the bleached coniferous wood pulp requires the following: a tensile index ≥80.0 N.m / g, an execution standard ISO1924-2; a burst index ≥8.0 KPa.m 2 / g, an execution standard ISO2758; a folding number ≥700 times, an execution standard ISO5626; a brightness ≥88.0%, an execution standard ISO3688;

[0155] The backing layer slurry is a combination of bleached coniferous wood pulp and chemi-mechanical pulp, specifically 20% bleached coniferous wood pulp + 80% chemi-mechanical pulp;

[0156] The raw material of the chemi-mechanical pulp is a combination of poplar, acacia and eucalyptus; specifically, 50% poplar + 50% eucalyptus;

[0157] The bleached softwood pulp contains no fluorescent substance, and the dustiness is less than or equal to 2.5 mm 2 / m 2 ;

[0158] The chemi-mechanical pulp contains no fluorescent substance, has a freeness of 300 CSF, a brightness of 75 degrees, a bulkiness of more than 2.0 cm 3 / g, a tensile index of more than 30 N.m / g, a fiber bundle content of less than 0.10%, and a pH value of 6.0-8.0;

[0159] The beating degree of the bleached softwood pulp is more than 50°SR, and the brightness of the chemi-mechanical pulp is more than 75°;

[0160] The core layer pulp is a combination of bleached softwood pulp (NBKP), chemi-mechanical pulp (TMP pulp) and broke paper, specifically, 10% bleached softwood pulp (NBKP) + 65% chemi-mechanical pulp (TMP pulp) + 25% broke paper;

[0161] The raw material of the chemi-mechanical pulp is a combination of poplar, acacia and eucalyptus; specifically, 50% poplar + 50% eucalyptus;

[0162] The pulp of the broke paper is obtained by defibrating, screening and refining the broke paper by a broke paper treatment system;

[0163] The bleached softwood pulp contains no fluorescent substance, and the dustiness is less than or equal to 2.5 mm

[0164] The beating degree of the bleached softwood pulp is more than 50°SR;

[0165] The bottom layer pulp is a combination of bleached hardwood pulp and bleached softwood pulp; the mass ratio of the bleached hardwood pulp to the bleached softwood pulp is 55:45;

[0166] The bleached softwood pulp contains no fluorescent substance, and the dustiness is less than or equal to 2.5 mm 2 / m 2 ;

[0167] The bleached softwood pulp has a freeness of (300±15) CSF, and the strength index requirements are as follows: a tensile index of more than 80.0 N.m / g according to the standard ISO 1924-2, and a burst index of more than 8.0 KPa.m 2Tearing resistance ≥ 40 times, according to standard ISO 5626; brightness ≥ 88.0%, according to standard ISO 3688.

[0168] The bleached hardwood pulp has no fluorescent substance and dust degree ≤ 2.5 mm 2 / m 2

[0169] The bleached hardwood pulp has no fluorescent substance and dust degree ≤ 2.5 mm 2 Tearing resistance ≥ 40 times, according to standard ISO 5626; brightness ≥ 88.0%, according to standard ISO 3688.

[0170] The pulp preparation aid includes a retention aid, a drainage aid, an internal sizing agent, an internal strengthening agent, and a system process aid;

[0171] The retention aid is a polyacrylamide (PAM) dry powder retention aid, the PAM dry powder retention aid is white particles, solid content ≥ 88 (oven drying method), viscosity (1%, 25℃) ≥ 550 (Brookfield LVDV-II viscometer), PH (0.3% aqueous solution, 25℃) is 3.0-6.0 (PHS-3C type PH meter);

[0172] The drainage aid includes an organic particulate drainage aid and a polyacrylamide (PAM) liquid drainage aid;

[0173] The organic particulate drainage aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, the model is V602, viscosity (0.5% aqueous solution, S62 / 5, 20℃) ≥ 500 (Brookfield LVDV-II viscometer); PH (0.5% aqueous solution, 20℃) is 7.0-9.5 (PHS-3C type PH meter);

[0174] The polyacrylamide (PAM) liquid drainage aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, the model is VL7035, viscosity (1%, 20℃, S62 / 5) mPa·s ≥ 700 (Brookfield viscometer); PH (0.1%, 20℃) is 3.0-7.0 (PHS-3C type PH meter);

[0175] The internal sizing agent includes rosin gum and aluminum sulfate;

[0176] The rosin size is anionic, white or light yellow emulsion, solid content is 35.3% (oven drying method); viscosity mpa·s (25℃, S61 / 100) ≤ 50 (Brookfield LVDV-II viscometer); PH (25℃) is 2.0-4.0 (PHS-3C type pH meter);

[0177] The aluminum sulfate is white or light yellow crystal, flaky; PH (1% aqueous solution 25℃) ≥ 3.0 (PHS-3C type pH meter); di-aluminum oxide content ≥ 15.8%, water insoluble ≤ 0.1%; iron ≤ 0.005%; the execution standard is HG / T 2225-2010;

[0178] The pulp internal reinforcing agent includes raw starch, cationic starch, dry strength agent, wet strength agent;

[0179] The dry strength agent is colorless transparent to slightly white viscous aqueous solution, the manufacturer is Japan starlight, the model is SK101, solid content is 20% (oven drying method); viscosity (25℃) is 5000-15000 mpa·s (Brookfield LVDV-II viscometer); pH (25℃) is 3-5 (PHS-3C type pH meter);

[0180] The wet strength agent manufacturer is Shandong Tiancheng Chemical, model is PAE-TC;

[0181] The system process aid includes defoaming agent, bactericide, system purifier, broken paper fixing agent;

[0182] The defoaming agent is a combination of alcohol defoaming agent and ether defoaming agent, wherein the mass ratio of alcohol defoaming agent and ether defoaming agent is 1:2.4;

[0183] The alcohol defoaming agent and ether defoaming agent manufacturers are Jining Nantian Agricultural Science, alcohol defoaming agent model is 8210, ether defoaming agent model is 526.

[0184] The alcohol defoaming agent is milky white to off-white emulsion, PH value (original solution, 25℃) is 5.5-8.0 (PHS-3C type pH meter); specific gravity (25℃) is 0.94-1.0 (mass volume method); viscosity (25℃, S62 / 50) ≤ 1500 (Brookfield LVDV-II viscometer);

[0185] The ether defoaming agent is brown oily liquid, specific gravity (25℃) is 0.94-1.0 (mass volume method); viscosity (25℃, S62 / 50) ≤ 700 (Brookfield LVDV-II viscometer); PH (1% aqueous solution) is 2-6 (PHS-3C type pH meter);

[0186] The bactericide includes a combination of a reaction-prepared bactericide and a preservative bactericide, wherein the mass ratio of the reaction-prepared bactericide to the preservative bactericide is 1:0.9;

[0187] The reaction-prepared bactericide includes a hypochlorous acid and ammonium sulfate reaction-type bactericide, wherein the mass ratio of the hypochlorous acid to the ammonium sulfate reaction-type bactericide is 3:1; the preservative bactericide is a hypochlorous acid and ammonium bromide reaction-type bactericide, wherein the mass ratio of the hypochlorous acid to the ammonium bromide reaction-type bactericide is 3:1;

[0188] The hypochlorous acid and ammonium bromide reaction-type bactericide is produced by Nantian Agricultural Science, wherein the model of the hypochlorous acid reaction-type bactericide is 9510, and the model of the ammonium bromide reaction-type bactericide is 9300.

[0189] The system purifying agent includes a deposit control agent, which is produced by Fumiomo and has a model of TEP-E, is a white emulsion liquid, has a PH (20℃) of 5.0-8.0 (PHS-3C type PH meter), and has a viscosity (S61 / 20, 20℃) of ≤30 (Bolife LVDV-II viscometer);

[0190] The broke paper fixing agent is a light yellow to yellow viscous liquid, which is produced by Fumiomo and has a model of FC702, a viscosity (20℃, S62 / 10) of ≥150 (Bolife LVDV-II viscometer), a PH (20℃) of 3.5-6.5 (PHS-3C type PH meter), and a specific gravity (20℃) of 0.95-1.20 (mass-volume method);

[0191] The dosage of the retention aid (mass fraction of the pulp) is 0.06% for the top layer, 0.06% for the lining layer, 0.06% for the core layer, and 0.06% for the bottom layer.

[0192] The dosage of the filter aid (mass fraction of the pulp) is 0.03% for the top layer, 0.03% for the lining layer, 0.03% for the core layer, and 0.03% for the bottom layer for the organic microparticle filter aid; and 0.05% for the core layer for the polyacrylamide (PAM) liquid filter aid.

[0193] The dosage of the internal sizing agent (mass fraction of the pulp) is 2.5% for the top layer, 3% for the lining layer, 3% for the core layer, and 2.5% for the bottom layer for the rosin sizing agent; and 0.8% for the top layer, 1.5% for the lining layer, 1.5% for the core layer, and 0.8% for the bottom layer for the aluminum sulfate.

[0194] The dosage of the internal strengthening agent (mass fraction of the pulp) is 0.5% for the top layer, 0.5% for the core layer, and 0.7% for the bottom layer for the raw starch; 0.5% for the top layer, 0.8% for the lining layer, 0.8% for the core layer, and 0.8% for the bottom layer for the cationic starch; 2.7% for the core layer for the dry strength agent; and 0.6% for the top layer, 0.8% for the lining layer, 0.8% for the core layer, and 0.8% for the bottom layer for the wet strength agent.

[0195] The dosage of the system process aid is (mass fraction of the pulp): defoaming agent: 0.05% for the surface layer, 0.05% for the backing layer, 0.05% for the core layer, and 0.07% for the bottom layer; bactericide: 0.05% for the surface layer, 0.05% for the backing layer, 0.05% for the core layer, and 0.03% for the bottom layer; system purifier: 0.015% for the surface layer, 0.05% for the backing layer, 0.05% for the core layer, and 0.025% for the bottom layer; broke fixing agent: 0.05% for the core layer;

[0196] In the use of the internal sizing agent, the internal sizing agent dosing point is optimized, the conventional aluminum sulfate dosing point and the rosin sizing agent dosing point are at the inlet of the pulp pump, the interval distance is too close, the aluminum ions are not fully combined with the fibers before the rosin sizing agent is added, which affects the sizing effect and leads to the excessive addition of the rosin sizing agent; in the embodiment, the aluminum sulfate dosing point is changed from the dilute pulp to the concentrated pulp and then to the preparation tank, the aluminum ions are fully combined with the fibers, and then the rosin sizing agent is reacted at the flow sending position, which improves the sizing effect and greatly reduces the chemical dosage;

[0197] In order to improve the sizing effect, a large amount of cationic additives, including retention aid, filter aid, rosin sizing agent, aluminum sulfate, cationic starch, and dry strength agent, are added to the system, the white water charge of the system is positive, the conductivity is high, the wet end system is disordered, the system retention rate is low, and the sizing is difficult; by optimizing the rosin sizing agent dosing point and combining with the paper machine operation, anionic rosin sizing agent is used to neutralize the excess cations in the system, reduce the system conductivity, improve the sizing efficiency, improve the charge environment of the wet end, and reduce the chemical dosage;

[0198] The raw starch is used as the interlayer spraying for the surface layer, the core layer, and the bottom layer;

[0199] The cationic starch and the wet strength agent are added in the pulp; specifically, the cationic starch is added at the inlet of the pre-pulping tank pump, the dry strength agent is added at the outlet of the pre-pulping tank pump, and the wet strength agent is added at the inlet of the preparation tank pump.

[0200] The type of the fluorescent eliminator is TAVA-706, which is a yellow liquid with positive ions, has a pH of 3.5-6, and is a polyimidazoline salt type fluorescent eliminator;

[0201] The elimination mechanism of the fluorescent eliminator is that the polyimidazoline salt group actively splits and reacts with the triazine amino group of the whitening agent to generate carboxyl and carbonyl compounds, which have the effect of quenching fluorescence, the molecules of fluorescent substances and the molecules of the eliminator react to generate coordination compounds that do not emit light by themselves, thereby eliminating the whitening agent (mainly styrene triazine derivatives) and eliminating the ability of the whitening agent to absorb ultraviolet light in the 335-365 nm wavelength range of sunlight;

[0202] The fluorescent eliminator has two adding points, one is used for intermittent adding in the wood pulp slurry and broadleaf wood pulp slurry machine, the adding amount is 0.5%, after detecting that the pulp has a fluorescence value of ≤0.1%, the amount is reduced to 0.2%; the other is added to the front pool of the mixed waste paper, the adding amount is 0.1%, the liquid level of each pulp tower and water tower is kept at 60%-70% during the adding period, stable control is required, and fluctuation is strictly prohibited.

[0203] Embodiment 3

[0204] The embodiment provides a raw material for waterproof and oil-proof coated card paper, which comprises pulp and pulp preparation aid;

[0205] The mass ratio of the pulp to the pulp preparation aid is 8.6:0.66;

[0206] The pulp comprises surface layer pulp, lining layer pulp, core layer pulp and bottom layer pulp; the mass ratio of the surface layer pulp, the lining layer pulp, the core layer pulp and the bottom layer pulp is 38:22:108:36;

[0207] The preparation method of the raw paper for waterproof and oil-proof coated card paper comprises the steps of compounding the surface layer pulp, the lining layer pulp, the core layer pulp and the bottom layer pulp, wherein the lining layer is first compounded with the core layer, then the surface layer is compounded, and finally the bottom layer is compounded;

[0208] The wood pulp used in the surface layer pulp, the lining layer pulp, the core layer pulp and the bottom layer pulp is virgin wood pulp fiber, which is free of fluorescent substances, clean, environmentally friendly and safe;

[0209] The surface layer pulp is a combination of bleached broadleaf wood pulp and bleached coniferous wood pulp, wherein the mass ratio of the bleached broadleaf wood pulp to the bleached coniferous wood pulp is 50:50;

[0210] The bleached coniferous wood pulp is free of fluorescent substances, and the dust degree is ≤2.5mm 2 / m 2 ;

[0211] Under the condition of a freeness of (300±15) CSF, the strength index of the bleached coniferous wood pulp requires the following: a tensile index ≥80.0 N.m / g, an execution standard ISO1924-2; a burst index ≥8.0 KPa.m 2 / g, an execution standard ISO2758; a folding number ≥700 times, an execution standard ISO5626; a brightness ≥88.0%, an execution standard ISO3688;

[0212] The bleached broadleaf wood pulp is free of fluorescent substances, and the dust degree is ≤2.5mm 2 / m 2 ;

[0213] The strength index requirements of the bleached broadleaf wood pulp under the condition of freeness (300±15) CSF are as follows: tensile index ≥ 50.0 N.m / g, execution standard ISO1924-2; burst index ≥ 5.0 KPa.m 2 / g, execution standard ISO2758; folding number ≥ 40 times, execution standard ISO5626; brightness ≥ 88.0%, execution standard ISO3688;

[0214] The lining pulp is a combination of bleached coniferous wood pulp and chemi-mechanical pulp, specifically 30% bleached coniferous wood pulp + 70% chemi-mechanical pulp;

[0215] The raw material of the chemi-mechanical pulp is a combination of poplar, acacia and eucalyptus, specifically 50% poplar + 30% acacia + 20% eucalyptus;

[0216] There is no fluorescent substance in the bleached coniferous wood pulp, and the dust degree is ≤2.5 mm 2 / m 2 ;

[0217] There is no fluorescent substance in the chemi-mechanical pulp, the freeness is 300 CSF, the brightness is 75 degrees, and the bulkiness is >2.0 cm 3 / g, the tensile index is >30 N·m / g, the fiber bundle content is <0.10%, and the pH value is 6.0-8.0;

[0218] The beating degree of the bleached coniferous wood pulp is more than 50°SR, and the brightness of the chemi-mechanical pulp is more than 75°;

[0219] The core layer pulp is a combination of bleached coniferous wood pulp (NBKP), chemi-mechanical pulp (TMP pulp) and broke paper, specifically 11% bleached coniferous wood pulp (NBKP) + 70% chemi-mechanical pulp (TMP pulp) + 19% broke paper;

[0220] The raw material of the chemi-mechanical pulp is a combination of poplar, acacia and eucalyptus, specifically 50% poplar + 30% acacia + 20% eucalyptus;

[0221] The pulp of the broke paper is obtained after the broke paper is defibrated, screened and milled by a broke paper treatment system;

[0222] There is no fluorescent substance in the bleached coniferous wood pulp, and the dust degree is ≤2.5 mm2 / m2; the chemi-mechanical pulp has no fluorescent substance, the freeness is 300 CSF, the brightness is 75 degrees, the bulkiness is >2.0 cm3 / g, the tensile index is >30 N·m / g, the fiber bundle content is <0.10%, and the pH value is 6.0-8.0;

[0223] The beating degree of the bleached coniferous wood pulp is more than 50°SR;

[0224] The bottom layer pulp is bleached broadleaf wood pulp + bleached coniferous wood pulp; wherein the mass ratio of bleached broadleaf wood pulp to bleached coniferous wood pulp is 60:40;

[0225] The bleached coniferous wood pulp is free of fluorescent substances and has a dust degree of ≤2.5 mm 2 / m 2 ;

[0226] The bleached coniferous wood pulp has the following strength index requirements under the condition of a freeness of (300±15) CSF: a tensile index of ≥80.0 N.m / g, according to the standard ISO 1924-2; a burst index of ≥8.0 KPa.m 2 / g, according to the standard ISO 2758; a folding number of ≥700 times, according to the standard ISO 5626; a brightness of ≥88.0%, according to the standard ISO 3688;

[0227] The bleached broadleaf wood pulp is free of fluorescent substances and has a dust degree of ≤2.5 mm 2 / m 2

[0228] The bleached broadleaf wood pulp has the following strength index requirements under the condition of a freeness of (300±15) CSF: a tensile index of ≥50 N.m / g, according to the standard ISO 1924-2; a burst index of ≥5.0 KPa.m 2 / g, according to the standard ISO 2758; a folding number of ≥40 times, according to the standard ISO 5626; a brightness of ≥88.0%, according to the standard ISO 3688.

[0229] The pulp preparation aid includes a retention aid, a filter aid, an internal sizing agent, an internal reinforcing agent, and a system process aid;

[0230] The retention aid is polyacrylamide (PAM) dry powder retention aid, which is white particles, has a solid content of ≥88 (oven drying method), a viscosity (1%, 25°C) of ≥550 (Brookfield LVDV-II viscometer), and a PH (0.3% aqueous solution, 25°C) of 3.0-6.0 (PHS-3C type PH meter);

[0231] The filter aid includes an organic particulate filter aid and polyacrylamide (PAM) liquid filter aid;

[0232] The organic particulate filter aid is a viscous liquid, produced by Jiangsu Fumiao, and has a viscosity (0.5% aqueous solution, S62 / 5, 20°C) of ≥500 (Brookfield LVDV-II viscometer) and a PH (0.5% aqueous solution, 20°C) of 7.0-9.5 (PHS-3C type PH meter);

[0233] The polyacrylamide (PAM) liquid filter aid is a viscous liquid, the manufacturer is Jiangsu Fumiao, the model is VL7035, the viscosity (1%, 20°C, S62 / 5) mPa·s≥700 (Bolife viscosity meter); PH (0.1%, 20°C) is 3.0-7.0 (PHS-3C type PH meter);

[0234] The internal sizing agent comprises rosin size and aluminum sulfate;

[0235] The rosin size is anionic, white or light yellow emulsion, the solid content is 35.8% (oven drying method); the viscosity mPa·s (25°C, S61 / 100)≤50 (Bolife LVDV-II viscosity meter); PH (25°C) is 2.0-4.0 (PHS-3C type PH meter);

[0236] The aluminum sulfate is white or light yellow crystal, flaky; PH (1% aqueous solution 25°C)≥3.0 (PHS-3C type PH meter); the aluminum trioxide content is≥15.8%, the water insoluble substance is≤0.1%; iron is≤0.005%; the execution standard is HG / T 2225-2010;

[0237] The internal strengthening agent comprises raw starch, cationic starch, dry strength agent, wet strength agent;

[0238] The dry strength agent is colorless transparent to slightly white viscous aqueous solution, the manufacturer is Japan Xingguang, the model is SK101, the solid content is 20% (oven drying method); the viscosity (25°C) is 5000-15000 mPa·s (Bolife LVDV-II viscosity meter); pH (25°C) is 3-5 (PHS-3C type PH meter);

[0239] The wet strength agent is produced by Shandong Tiancheng Chemical, the model is PAE-TC;

[0240] The system process aid comprises defoaming agent, bactericide, system purifier, broken paper fixing agent;

[0241] The defoaming agent is a combination of alcohol defoaming agent and ether defoaming agent, wherein the mass ratio of alcohol defoaming agent to ether defoaming agent is 1.2:1.8;

[0242] The alcohol defoaming agent and the ether defoaming agent are produced by Jining Nantian Agricultural Science, the alcohol defoaming agent is model 8210, and the ether defoaming agent is model 526.

[0243] The alcohol defoaming agent is milky white to off-white emulsion, the PH value (original solution, 25°C) is 5.5-8.0 (PHS-3C type PH meter); the specific gravity (25°C) is 0.94-1.0 (mass-volume method); the viscosity (25°C, S62 / 50)≤1500 (Bolife LVDV-II viscosity meter);

[0244] The ether antifoaming agent is a brown oily liquid, the specific gravity (25℃) is 0.94-1.0 (mass-volume method); the viscosity (25℃, S62 / 50) is ≤700 (Bolife LVDV-II viscometer); the PH (1% aqueous solution) is 2-6 (PHS-3C type PH meter);

[0245] The bactericide includes a combination of a reaction-prepared bactericide and a preservative bactericide, wherein the mass ratio of the reaction-prepared bactericide to the preservative bactericide is 1.2:1.1;

[0246] The reaction-prepared bactericide includes a hypochlorous acid and ammonium sulfate reaction type bactericide, wherein the mass ratio of the hypochlorous acid to the ammonium sulfate reaction type bactericide is 3.1:1; the preservative bactericide is a hypochlorous acid and ammonium bromide reaction type bactericide, wherein the mass ratio of the hypochlorous acid to the ammonium bromide reaction type bactericide is 3.1:1;

[0247] The production factory of the hypochlorous acid and ammonium bromide reaction type bactericide is Nantian Agricultural Science, wherein the model of the hypochlorous acid reaction type bactericide is 9510, and the model of the ammonium bromide reaction type bactericide is 9300.

[0248] The system purifier includes a deposit control agent, the production factory is Fumi, the model is TEP-E, Jiangsu is a white emulsion, the PH (20℃) is 5.0-8.0 (PHS-3C type PH meter); the viscosity (S61 / 20, 20℃) is ≤30 (Bolife LVDV-II viscometer);

[0249] The broke paper fixing agent is a light yellow to yellow viscous liquid, the production factory is Fumi, the model is FC702, the viscosity (20℃, S62 / 10) is ≥150 (Bolife LVDV-II viscometer); the PH (20℃) is 3.5-6.5 (PHS-3C type PH meter); the specific gravity (20℃) is 0.95-1.20 (mass-volume method);

[0250] The dosage of the retention aid (mass fraction of the pulp) is: 0.06% for the surface layer, 0.06% for the lining layer, 0.06% for the core layer, and 0.06% for the bottom layer;

[0251] The dosage of the filter aid (mass fraction of the pulp) is: 0.03% for the organic microparticle filter aid for the surface layer, the lining layer, the core layer, and the bottom layer; and 0.05% for the polyacrylamide (PAM) liquid filter aid for the core layer;

[0252] The dosage of the internal sizing agent is (mass fraction of the pulp): rosin size 2.5% for the surface layer, 3% for the lining layer, 3% for the core layer, and 2.5% for the bottom layer; aluminum sulfate 0.8% for the surface layer, 1.5% for the lining layer, 1.5% for the core layer, and 0.8% for the bottom layer;

[0253] The dosage of the internal strengthening agent is (mass fraction of the pulp): raw starch 0.7% for the surface layer, 0.8% for the core layer, and 0.3% for the bottom layer; cationic starch 0.6% for the surface layer, 0.8% for the lining layer, 0.8% for the core layer, and 0.5% for the bottom layer; dry strength agent 3.8% for the core layer; and wet strength agent 0.9% for the surface layer, 1.5% for the lining layer, 1.5% for the core layer, and 1% for the bottom layer;

[0254] The dosage of the system process aid is (mass fraction of the pulp): defoaming agent 0.07% for the surface layer, 0.08% for the lining layer, 0.08% for the core layer, and 0.03% for the bottom layer; bactericide 0.04% for the surface layer, 0.05% for the lining layer, 0.05% for the core layer, and 0.03% for the bottom layer; system purifier 0.02% for the surface layer, 0.045% for the lining layer, 0.045% for the core layer, and 0.03% for the bottom layer; and broke fixing agent 0.025% for the core layer;

[0255] In the use of the internal sizing agent, the dosing point of the internal sizing agent is optimized, the dosing points of the conventional aluminum sulfate and rosin size are at the inlet of the pulp slurry pump, and the interval distance is too close. The aluminum ions are not fully combined with the fibers before the rosin size is added, which affects the sizing effect and leads to an excessively high amount of rosin size. In the embodiment, the dosing point of the aluminum sulfate is changed from the dilute pulp to the concentrated pulp and then to the ingredient pool. The aluminum ions are fully combined with the fibers before the rosin size is added at the flow delivery point, which improves the sizing effect and greatly reduces the amount of chemical used.

[0256] To improve the sizing effect, a large amount of cationic aids, including retention aid, filter aid, rosin size, aluminum sulfate, cationic starch, and dry strength agent, are added to the system. The white water of the system has positive charge and high conductivity, which causes disorder in the wet end system, low retention rate of the system, and difficulty in sizing. By optimizing the dosing point of the rosin size and combining with the operation of the paper machine, anionic rosin size is used to neutralize the excess cations in the system, reduce the conductivity of the system, improve the sizing efficiency, improve the charge environment in the wet end, and reduce the amount of chemical used.

[0257] The raw starch is used as the interlayer spray for the surface layer, the core layer, and the bottom layer.

[0258] The cationic starch and the wet strength agent are added internally. Specifically, the cationic starch is added at the inlet of the pre-pulping pool pump, the dry strength agent is added at the outlet of the pre-pulping pool pump, and the wet strength agent is added at the inlet of the ingredient pool pump.

[0259] The fluorescent eliminator is model TAVA-706, a yellow liquid with positive charge, pH 3.5-6, and a polyimidazoline salt type fluorescent eliminator.

[0260] The elimination mechanism of the fluorescent eliminator is that the polyimidazoline salt group is actively cracked and the triazine amino group of the whitening agent is neutralized to form carboxyl and carbonyl compounds, which have the effect of quenching fluorescence. The molecules of fluorescent substances and the molecules of the eliminator react to form coordination compounds that do not emit light, thereby eliminating the whitening agent (main component: styrene triazine derivative) and eliminating the ability of the whitening agent to absorb ultraviolet light in the range of 335-365 nm of sunlight;

[0261] The fluorescent eliminator has two addition points. One is for intermittent addition in the needle wood pulp pulper and the broadleaf wood pulp pulper, and the addition amount is 0.5%. After detecting that the fluorescence value of the pulp is ≤0.1%, the amount is reduced to 0.2%. The other is to add the fluorescent eliminator to the mixing broke paper pool before the beater, and the addition amount is 0.1%. During the addition, the liquid levels of the pulp tower and the water tower are kept at 60%-70% to be stably controlled, and fluctuations are strictly prohibited.

[0262] Example 4

[0263] A kind of according to the composition of waterproof and oil-proof coated paper for example 1, the method for preparing waterproof and oil-proof coated paper for example 1, specifically:

[0264] 1. Beating

[0265] The beating process is: pulping - storage tower - high consistency sand removal - double disc mill - post-beating pool;

[0266] After beating, the freeness of the NBKP bleached needle wood pulp and the LBKP bleached broadleaf wood pulp is 325 mL, and the degree of beating is 38°SR. The freeness of the BCTMP chemi-mechanical pulp is 280 mL, and the degree of beating is 42°SR. The freeness of the bleached needle wood pulp (used for lining and core layers) is 210 mL, and the degree of beating is 50°SR.

[0267] After the raw material is beaten, the inner and outer walls of the fibers are separated and flocked, and the bonding strength between the fibers is improved, thereby enhancing the physical strength indexes of the paper, such as tensile strength, burst strength, folding endurance, etc.

[0268] 2. Sizing

[0269] The sizing processes of the four layers of surface, lining, core and bottom are the same, and the specific process is: post-beating pool - mixing tank - sizing tank (mixing and sizing in the sizing tank) - paper machine flow delivery system; the setting scheme is automatically controlled through the DCS system.

[0270] According to the process ratio of each layer of pulp, the mixing of various pulp amounts is controlled, and after sufficient mixing and uniformity, the pulp is fed into the sizing tank to the paper machine flow delivery system, and then sprayed onto the wire through the paper machine headbox to form.

[0271] According to the process ratio of each layer of pulp, the mixing of different pulps is stably and uniformly achieved, thereby meeting the quality stability requirements of the paper.

[0272] 3. Headbox

[0273] The headbox process is: slurry tank - sand remover - degasser - slurry pump - pre-screening - pulse attenuation tank - headbox;

[0274] According to the process design and running speed requirements, set the appropriate concentration of the screen, headbox jet speed;

[0275] This process has three main effects, one is the last impurity purification of the slurry, to ensure the quality of the paper; two is to remove the free air in the slurry, improve the filter and provide paper quality; three is the flow and pressure to reach the headbox, reduce the pulse or no pulse, to ensure the stability of the paper quality.

[0276] 4. Forming on the wire

[0277] The surface, liner, core, bottom layer through the headbox respectively slurry uniform stable jet to the forming wire case, slurry with the forming wire forward transmission, through the forming wire bottom of the water plate, low vacuum box, high vacuum box gradually dewatering to the process requirements.

[0278] The top of the core layer is configured with a top wire, and the slurry is dewatered through the upper and lower nets. The dewatering capacity is strengthened, and the slurry is gradually dewatered through the water plate, low vacuum box and high vacuum box at the bottom of the forming wire to the process requirements.

[0279] The surface layer slurry concentration is 0.54%, the liner layer slurry concentration is 0.44%, the core layer slurry concentration is 0.8%, and the bottom layer slurry concentration is 0.58%.

[0280] The surface, liner, core, and bottom four layers are controlled within 11.3% before compounding, and the paper dryness of the four layers is controlled within 22.5% after compounding. During compounding, the liner layer is first compounded with the core layer, then compounded with the surface layer, and finally compounded with the bottom layer. Vacuum compounding can be achieved by adjusting the vacuum degree of the compounding roller. After compounding, the subsequent pressing step is carried out.

[0281] The main two functions of the wire forming are: one is forming, the fiber is sprayed out of the headbox, and the wet paper sheet with uniform quantity is formed on the wire; two is dewatering, the water in the slurry sprayed by the headbox is removed by 95% in the wire, which greatly saves the subsequent dewatering and drying cost.

[0282] 5. Pressing

[0283] The paper is pressed by three straight-through type boots to further remove the water in the wet paper web transmitted from the wire, and the paper dryness is continuously improved. The linear pressure of the three boot presses is set in the range of 1000 kN / m; the paper dryness after the press is in the range of 50.3%.

[0284] The free water in the wet paper web is further removed by a press section, which removes 3% of the water in the pulp jetted out by the headbox, reducing the steam consumption cost of the evaporation drying by the drying cylinder.

[0285] The present process adopts a shoe press, which has the characteristics of high linear pressure and wide press nip, and can remove a large amount of water from the wet paper web in the press nip, has high efficiency, is relatively energy-saving, and can realize a high line speed of more than 1000 m / min.

[0286] 6. Pre-drying

[0287] The paper web is dried by the drying section, and the moisture content of the pre-dried paper web is controlled at 9%. After pre-drying, the base paper for waterproof and oil-proof coated paper is obtained.

[0288] The bound water in the paper web is evaporated and removed, so that the paper web reaches the required dryness and is given appropriate physical strength indexes.

[0289] The base paper for waterproof and oil-proof coated paper prepared in the present embodiment has a fluorescence value of ≤0.1%, and a paper edge bleeding stability of ≤3 mm (10 min in hot water at 95°C), which meets the requirements of subsequent secondary processing of the paper.

[0290] Example 5

[0291] A method for preparing a base paper for waterproof and oil-proof coated paper according to the composition of the base paper for waterproof and oil-proof coated paper in Example 2, specifically comprising:

[0292] 1. Beating

[0293] The beating process is: pulping - pulp storage tower - high consistency sand removal - double-disc refiner - post-beating pool.

[0294] After beating, the freeness of the NBKP bleached softwood pulp and the LBKP bleached hardwood pulp is 325 mL, and the degree of defibration is 38°SR; the freeness of the BCTMP chemi-mechanical pulp is 280 mL, and the degree of defibration is 42°SR; the freeness of the bleached softwood pulp (used for the lining and core layers) is 210 mL, and the degree of defibration is 50°SR.

[0295] After the raw material is treated by beating, the fibers are separated and flocked on the inner and outer walls, and the bonding strength between the fibers is improved, thereby enhancing the physical strength indexes of the paper, such as tensile strength, burst strength, and folding endurance.

[0296] 2. Slurry preparation

[0297] The slurry preparation processes of the four layers of surface, lining, core, and bottom are the same, and the specific process is: post-beating pool - mixing tank - slurry forming tank (slurry is mixed and prepared in the slurry forming tank) - paper machine conveying system; the setting scheme is automatically controlled by the DCS system.

[0298] According to the process ratio of each layer of pulp, the mixing of various pulp quantities is controlled, and after sufficient mixing, it is fed into the pulp tank to the paper machine flow system and then sprayed onto the forming wire through the paper machine headbox.

[0299] According to the process ratio of each layer of pulp, the mixing of various pulp quantities is controlled, and after sufficient mixing, it is fed into the pulp tank to the paper machine flow system and then sprayed onto the forming wire through the paper machine headbox.

[0300] 3. Flow

[0301] The flow process is: pulp tank - sand remover - degasser - pulp pump - pre-screen - pulse attenuation tank - headbox

[0302] According to the process design and running speed requirements, the appropriate wire density and headbox spray speed are set;

[0303] This process mainly has three effects: first, the last impurity purification of the pulp, to ensure the quality of the paper; second, to remove the free air in the pulp, to improve the filter water in the wire part and to provide the paper quality; third, the stable flow and pressure to the headbox, to reduce the pulse or no pulse, to ensure the stability of the paper quality.

[0304] 4. Wire forming

[0305] The surface, lining, core and bottom layers are uniformly and stably sprayed onto the forming wire case through the headbox, and the pulp is transmitted forward with the forming wire, and gradually dehydrated through the water scraping plate, low vacuum box and high vacuum box at the bottom of the forming wire to the process requirement value.

[0306] The top layer of the core is configured with a top wire, and the pulp is dehydrated up and down through the clamping area of the upper and lower wires to strengthen the dehydration capacity, and is gradually dehydrated through the water scraping plate, low vacuum box and high vacuum box at the bottom of the forming wire to the process requirement value.

[0307] The surface layer pulp concentration is 0.75%, the lining layer pulp concentration is 0.65%, the core layer pulp concentration is 1.25%, and the bottom layer pulp concentration is 0.77%.

[0308] The surface, lining, core and bottom four layers are controlled within 11.3% before compounding, and the paper dryness of the four layers after compounding is controlled within 22.5%. During compounding, the lining layer is compounded with the core layer first, then with the surface layer, and finally with the bottom layer. The vacuum degree of the compounding roller can be adjusted, and the subsequent pressing step is carried out after compounding.

[0309] The main two effects of wire forming are: one is forming, the fiber is sprayed out through the headbox, and a uniform wet paper sheet is formed in the wire part; the second is dehydration, the water in the pulp sprayed out of the headbox is removed by 95% in the wire part, which greatly saves the cost of subsequent dehydration and drying.

[0310] 5. Pressing

[0311] The paper is pressed by three straight-through shoes to further remove the water in the wet paper web from the wire section, and to continue to increase the paper dryness. The linear pressure of the three shoe presses is set to 1000 kN / m; the paper dryness after the press is in the range of 50.3%.

[0312] The free water in the wet paper web is further removed by the press section, which removes 3% of the water in the pulp ejected from the headbox, reducing the steam consumption cost of evaporation drying by the drying cylinder.

[0313] The process uses shoe presses, which are characterized by high linear pressure and wide press area, large water removal from the wet paper web in the press area, high efficiency, relative energy saving, and the realization of high line speed of more than 1000 m / min.

[0314] 6. Pre-drying

[0315] The paper is dried by the drying section, and the water content of the pre-dried paper is controlled at 9%. After pre-drying, the base paper for waterproof and oil-proof coated card paper is obtained;

[0316] The bound water in the paper is evaporated and removed to achieve the required paper dryness and give the paper appropriate physical strength indicators;

[0317] The base paper for waterproof and oil-proof coated card paper prepared in this example has a fluorescence value of ≤0.1%, and the paper edge bleeding stability is stably controlled at ≤3 mm (10 min in hot water at 95°C), meeting the requirements of subsequent secondary processing of paper.

[0318] Example 6

[0319] A base paper for waterproof and oil-proof coated card paper according to the composition of Example 3, a method for preparing a base paper for waterproof and oil-proof coated card paper, specifically:

[0320] 1. Beating

[0321] The beating process is: pulping - pulp storage tower - high consistency sand removal - double disc mill - beating pool;

[0322] After beating, the freeness of the NBKP bleached softwood pulp and the LBKP bleached hardwood pulp is 325 mL, and the degree of beating is 38°SR; the freeness of the BCTMP chemi-mechanical pulp is 280 mL, and the degree of beating is 42°SR; the freeness of the bleached softwood pulp (used for lining and core layer) is 210 mL, and the degree of beating is 50°SR;

[0323] After the raw materials are treated by beating, the fibers inside and outside the wall are separated and flocked, and the bonding strength between the fibers is improved. Thus, the physical strength indicators of the finished paper such as tensile strength, burst strength, folding endurance, etc. are enhanced.

[0324] 2. Sizing

[0325] The four-layer pulp mixing process is the same, and the specific process is as follows: knock pool-mixing tank-pulp tank (pulp mixing is carried out in the pulp tank)-paper machine flow system; the setting scheme is automatically controlled through the DCS system.

[0326] According to the process ratio of each layer of pulp, the mixing of various pulp amounts is controlled, and after sufficient mixing, it is fed into the pulp tank to the paper machine flow system and then sprayed onto the forming wire through the paper machine headbox.

[0327] According to the process ratio of each layer of pulp, the mixing of different pulps is stably and uniformly realized, so as to meet the quality stability requirement of the formed paper.

[0328] 3. Flow

[0329] The flow process is as follows: pulp tank-sand remover-degasser-pulp pump-pre-screen-pulse attenuation tank-flow box

[0330] According to the process design and running speed requirement, the appropriate spraying concentration on the wire and the spraying speed of the flow box are set.

[0331] This process mainly has three effects: the last impurity removal and purification of the pulp, which ensures the quality of the paper sheet; the removal of free air in the pulp, which improves the wire section filtration and provides the quality of the formed paper; and the stable flow and pressure to the flow box, which reduces the pulse or no pulse and ensures the stability of the quality of the formed paper.

[0332] 4. Wire forming

[0333] The face, liner, core and bottom layers are respectively sprayed onto the forming wire through the flow box, and the pulp is gradually dewatered through the water scraping plate, low vacuum box and high vacuum box at the bottom of the forming wire to the process requirement value.

[0334] The core layer is provided with a top wire, and the pulp is dewatered through the upper and lower wires, thereby strengthening the dewatering capacity, and the pulp is gradually dewatered through the water scraping plate, low vacuum box and high vacuum box at the bottom of the forming wire to the process requirement value.

[0335] The concentration of the face layer pulp is 0.44%, the concentration of the liner layer pulp is 0.64%, the concentration of the core layer pulp is 0.78%, and the concentration of the bottom layer pulp is 0.54%.

[0336] The dryness of the paper sheet before the four layers are compounded is controlled within 11.3%, and the dryness of the paper sheet after the four layers are compounded is controlled within 22.5%. During the compounding, the liner layer is compounded with the core layer first, then the face layer is compounded, and finally the bottom layer is compounded. The vacuum compounding is carried out by the compounding roller, the vacuum degree of the compounding roller can be adjusted, and the subsequent pressing step is carried out after the compounding.

[0337] The main two functions of the wire section are: one is forming, the fibers are sprayed out through the headbox, and a uniform wet paper sheet is formed in the wire section; the other is dewatering, the water in the pulp sprayed out through the headbox is removed by 95% in the wire section, greatly saving the subsequent dewatering and drying cost.

[0338] 5. Pressing

[0339] The wet paper web is further pressed to remove the water in the wet paper web transmitted from the wire section through three straight-through shoe presses, and the dryness of the paper sheet is continuously improved. The linear pressure of the three shoe presses is set to be in the range of 1000 kN / m; the dryness of the paper sheet after the pressing is in the range of 50.3%.

[0340] The free water in the wet paper web is further removed through the pressing section, and the pressing section removes 3% of the water in the pulp sprayed out through the headbox, reducing the steam consumption cost of evaporation drying through the dryer.

[0341] The process adopts shoe pressing, which has the characteristics of high linear pressure and wide press area, large water removal amount of the wet paper web in the press area, high efficiency, relative energy saving, and high speed of more than 1000 m / min.

[0342] 6. Pre-drying

[0343] The paper sheet is dried through the drying section, and the water content of the paper sheet after pre-drying is controlled to be 9%, and the waterproof and oil-proof coating base paper is obtained after pre-drying;

[0344] The bound water in the paper sheet is evaporated and removed to reach the required dryness of the paper sheet and give the paper sheet appropriate physical strength indicators;

[0345] The waterproof and oil-proof coating base paper prepared in the example has a fluorescence value of ≤0.1%, and the paper sheet bleeding is stably controlled to be ≤3 mm (10 min in 95°C hot water), meeting the requirements of subsequent secondary processing of the paper sheet.

[0346] Comparative Example 1

[0347] The same raw materials of the waterproof and oil-proof coating base paper as in Example 1 and the same method of preparing the waterproof and oil-proof coating base paper as in Example 4 are used, except that the addition points of aluminum sulfate and rosin gum in the surface layer, the backing layer, the core layer, and the bottom layer are changed, and the addition points of aluminum sulfate and rosin gum are changed to the inlet of the pulp pump;

[0348] The waterproof and oil-proof coating base paper prepared in the comparative example has a fluorescence value of ≤0.1%, and the paper sheet bleeding is >3 mm (10 min in 95°C hot water).

[0349] Comparative Example 2

[0350] The same raw material of the water-proof and oil-proof coated paper base paper as in Example 1 and the same method of preparing the water-proof and oil-proof coated paper base paper as in Example 4 are adopted, except that the adding points of aluminum sulfate and rosin size in the surface layer, the lining layer, the core layer and the bottom layer are changed, and the adding points of aluminum sulfate and rosin size are both changed to the inlet of the pulp pump, and the adding amount of rosin size is doubled.

[0351] The water-proof and oil-proof coated paper base paper prepared in the present comparative example has a fluorescence value of ≤0.1%, and the paper edge seepage stability control is ≤3mm (10min in 95℃ hot water), which meets the requirements of subsequent paper secondary processing.

[0352] As can be seen from the results of Comparative Example 1 and Comparative Example 2, after changing the adding points of aluminum sulfate and rosin size, because the interval distance between the adding points of aluminum sulfate and rosin size is too close, the aluminum ions are not fully combined with the fibers before the addition of rosin size, which affects the sizing effect. In order to achieve the required sizing effect, the amount of rosin size needs to be increased, thereby leading to an increase in sizing cost.

[0353] Comparative Example 3

[0354] The same raw material of the water-proof and oil-proof coated paper base paper as in Example 1 and the same method of preparing the water-proof and oil-proof coated paper base paper as in Example 4 are adopted, except that the adding points of the fluorescence eliminating agent are changed from two to one, and the amounts of the two adding points are combined, specifically, the fluorescence eliminating agent is changed to be added intermittently only in the needle pulp and broadleaf pulp pulpers, and the adding amount is 0.6%. When the fluorescence value of the pulp is >0.1% for a long time, it is gradually reduced to ≤0.1%, and a large number of transition products are produced during this period.

[0355] Comparative Example 4

[0356] The same raw material of the water-proof and oil-proof coated paper base paper as in Example 1 and the same method of preparing the water-proof and oil-proof coated paper base paper as in Example 4 are adopted, except that the adding points of the fluorescence eliminating agent are changed from two to one, and the amounts of the two adding points are combined, specifically, the fluorescence eliminating agent is changed to be added intermittently only in the needle pulp and broadleaf pulp pulpers, and the adding amount is 1.2%. When the fluorescence value of the pulp is ≤0.1%, the amount is reduced to 0.4%.

[0357] The water-proof and oil-proof coated paper base paper prepared in the present comparative example has a fluorescence value of ≤0.1%, and the paper edge seepage stability control is ≤3mm (10min in 95℃ hot water), which meets the requirements of subsequent paper secondary processing.

[0358] From the results of Comparative Example 3 and Comparative Example 4, it can be seen that after the adding point of the fluorescence eliminating agent is changed from two to one and the amount of the two adding points is combined, the fluorescence value in the slurry is always maintained at a high level, the amount of the fluorescence eliminating agent needs to be increased to reduce the fluorescence value to ≤0.1%, and a large amount of transition products are produced, indicating that changing the adding point of the fluorescence eliminating agent to two can effectively reduce the amount of the fluorescence eliminating agent and reduce the transition products.

[0359] The above is an example of the best mode of the present application, wherein the parts not described in detail are all the common knowledge of ordinary skilled in the art. The protection scope of the present application is subject to the content of the claims, and any equivalent transformation based on the technical inspiration of the present application is also within the protection scope of the present application.

Claims

1. A method for preparing a base paper for waterproof and oil-resistant coated cardboard, characterized in that, The raw materials for the paper include pulp and pulping aids; The pulping aids include retention aids, filter aids, in-slurry sizing agents, in-slurry reinforcing agents, system process aids, and fluorescence eliminators; The sizing agent used in the slurry includes rosin gum and aluminum sulfate; Rosin gum is anionic, with a solid content of 34-36%. The aluminum sulfate is added at the mixing tank, and the rosin is added at the flow point. The system process additives include defoamers, bactericides, system purifiers, and paper fixatives; The fluorescence scavenger is designated TAVA-706, a yellow liquid with cationic properties, a pH of 3.5-6, and is a polyimidazoline salt type fluorescence scavenger. The fluorescence scavenger has two addition points. One is to add it intermittently inside the pulping machine for both softwood and hardwood pulp, with an addition amount of 0.5%. After the fluorescence value of the pulp is detected to be ≤0.1%, the dosage is reduced to 0.2%. The other is to add it in the mixing waste paper tapping tank, with an addition amount of 0.1%. During the addition, the liquid level of each pulping tower and water tower is maintained at 60%-70%.

2. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 1, characterized in that, The mass ratio of the slurry to the slurry preparation aid is 8-9:0.65-0.75; The slurry includes a surface slurry, a lining slurry, a core slurry, and a bottom slurry; wherein the mass ratio of the surface slurry, the lining slurry, the core slurry, and the bottom slurry is 40-44:25-30:76-106:34-42.

3. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 1, characterized in that, The waterproof and oil-resistant coated cardboard is a composite of a surface layer, a liner layer, a core layer, and a bottom layer. During the lamination process, the liner layer is first laminated with the core layer, then with the surface layer, and finally with the bottom layer. The surface slurry is a combination of bleached hardwood pulp and bleached softwood pulp; The lining slurry is a combination of bleached softwood pulp and chemimechanical pulp; The core layer pulp is bleached softwood pulp + chemimechanical pulp + waste paper or chemimechanical pulp + waste paper; The underlying pulp is composed of bleached hardwood pulp and bleached softwood pulp.

4. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 1, characterized in that, The retention aid is a polyacrylamide dry powder retention aid; The filter aid includes organic particulate filter aid and polyacrylamide liquid filter aid; The organic particulate filter aid is a viscous liquid, manufactured by Jiangsu Fumiao, and its model number is V602. The polyacrylamide liquid filter aid is a viscous liquid, manufactured by Jiangsu Fumiao, and its model is VL7035. The pulp strengthening agent includes native starch, cationic starch, dry strength agent, and wet strength agent; The dry strength agent is a colorless, transparent to slightly white viscous aqueous solution, manufactured by Hoshikatsu Japan, and its model is SK101. The wet strength agent is manufactured by Shandong Tiancheng Chemical Co., Ltd., and its model number is PAE-TC.

5. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 1, characterized in that, The retention aid is used in the following amounts: surface layer slurry 0.06%, lining layer slurry 0.06%, core layer slurry 0.06%, and bottom layer slurry 0.06%. The dosage of the filter aid is as follows: organic particulate filter aid: 0.03% for surface layer slurry, 0.03% for lining slurry, 0.03% for core layer slurry, and 0.03% for bottom layer slurry; polyacrylamide liquid filter aid: 0.05% for core layer slurry; The dosage of the sizing agent in the slurry is as follows: rosin adhesive: 2.5% for the surface layer slurry, 3% for the lining layer slurry, 3% for the core layer slurry, and 2.5% for the bottom layer slurry; Aluminum sulfate: surface slurry 0.8%, lining slurry 1.5%, core slurry 1.5%, bottom slurry 0.8%; The dosage of the in-slurry strengthening agent is as follows: native starch: surface layer slurry 0.2-0.8%, core layer slurry 0.2-0.8%, bottom layer slurry 0.2-0.8%; cationic starch: surface layer slurry 0.2-0.8%, lining layer slurry 0.4-1%, core layer slurry 0.4-1%, bottom layer slurry 0.2-0.8%; dry strength agent: core layer slurry 2-4%; wet strength agent: surface layer slurry 0.2-1.2%, lining layer slurry 0.5-1.5%, core layer slurry 0.5-1.5%, bottom layer slurry 0.2-1.2%. The dosage of process additives in the system is as follows: Defoamer: 0.01-0.08% for top layer slurry, 0.03-0.09% for liner slurry, 0.03-0.09% for core layer slurry, and 0.01-0.08% for bottom layer slurry; Bactericide: 0.01-0.05% for top layer slurry, 0.02-0.06% for liner slurry, 0.02-0.06% for core layer slurry, and 0.01-0.05% for bottom layer slurry; System purifying agent: 0.01-0.03% for top layer slurry, 0.01-0.05% for liner slurry, 0.01-0.05% for core layer slurry, and 0.01-0.03% for bottom layer slurry; Paper fixing agent: 0.01-0.05% for core layer slurry.

6. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 4, characterized in that, The original starch is used as an interlayer spray for the surface layer, core layer, and bottom layer; The cationic starch and wet strength agent are added into the slurry; the cationic starch is added at the inlet of the pre-scouring pool pump; the dry strength agent is added at the outlet of the pre-scouring pool pump; and the wet strength agent is added at the inlet of the batching pool pump.

7. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 1, characterized in that, The preparation method includes: pulping, pulp preparation, conveying, screen forming, and pre-drying.

8. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 7, characterized in that, The pulping process is as follows: pulping - pulp storage tower - high-consistency sand removal - double-disc mill - post-beating pool; After beating, the freeness of NBKP bleached softwood pulp and LBKP bleached hardwood pulp was 325 mL, and the freeness of LBKP bleached hardwood pulp was 38°SR; the freeness of BCTMP chemimechanical pulp was 280 mL, and the freeness of LBKP bleached softwood pulp was 42°SR; and the freeness of bleached softwood pulp was 210 mL, and the freeness of LBKP bleached hardwood pulp was 50°SR.

9. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 7, characterized in that, The pulp preparation process is the same for the four layers: top layer, liner, core layer, and bottom layer. The process is as follows: tapping tank - mixing tank - pulping tank - paper machine flow system; The conveying process is as follows: slurry tank - desander - deaerator - slurry pump - pre-screen - pulse attenuation tank - headbox.

10. The method for preparing the base paper for waterproof and oil-resistant coated cardboard according to claim 7, characterized in that, The mesh forming process involves uniformly and stably spraying slurry onto the forming mesh through a headbox for the surface, lining, core, and bottom layers. As the forming mesh moves forward, the slurry is gradually dehydrated through a scraper at the bottom of the mesh, a low-vacuum chamber, and a high-vacuum chamber. A top mesh is placed on top of the core layer, allowing the slurry to be dehydrated vertically through the gap between the upper and lower meshes, enhancing the dehydration capacity. Additionally, the slurry is gradually dehydrated through the scraper at the bottom of the mesh, a low-vacuum chamber, and a high-vacuum chamber, ultimately resulting in a slurry concentration of 0.4-0.8% for the surface layer, 0.4-0.8% for the lining layer, 0.5-1.3% for the core layer, and 0.4-0.8% for the bottom layer. The paper sheet dryness of the four layers (face, liner, core, and bottom) is controlled within the range of 10%-14% before lamination, and within the range of 20%-24% after lamination. During lamination, the liner is first laminated with the core layer, then with the face layer, and finally with the bottom layer. Vacuum lamination is performed by a laminating roller, and the vacuum degree of the laminating roller is adjusted. Subsequent pressing steps are then performed after lamination. The pressing process involves three straight-through shoe presses to further remove moisture from the wet paper web transmitted from the wire section, thereby increasing the paper's dryness. The three-shoe press is used, with a pressure setting range of 800-1250 kN / m. The dryness of the paper after pressing ranges from 48% to 52%. The pre-drying process involves drying the paper sheets in a drying section, with the moisture content of the pre-dried paper sheets controlled at 6%-12%, to obtain base paper for waterproof and oil-resistant coated cardboard.