Method for reducing methanol release amount of white cardboard for cigarettes

Abstract

According to the method for reducing the methanol release amount of the white cardboard for the cigarette, the white cardboard for the cigarette is prepared in the mode that a citric acid solution is sprayed to the surface of a core layer handsheet, and the reaction of chemical auxiliaries in core layer slurry is not affected in the mode; according to the method, a citric acid solution is directly sprayed to the surface of the core layer handsheet in an atomization spraying mode, citric acid is in direct contact with core layer slurry, and the method is easy to operate and can effectively reduce the release amount of methanol of the cigarette white cardboard subjected to ultraviolet drying.

Description

Technical Field

[0001] The invention belongs to the technical field of papermaking, and in particular relates to a method for reducing the methanol release of white cardboard for cigarettes. Background Art

[0002] Methanol is a toxic volatile organic compound (VOC). Its ingestion or long-term exposure to an environment with excessive methanol content can cause a variety of discomfort symptoms in the human body. Many countries and regions have set limits on the methanol content in food packaging paper and cigarette paper. Cigarette white cardboard is a high-quality paper specially used for cigarette packaging. Cigarette white cardboard has good printing suitability, a smooth surface, and can present clear and bright color patterns. UV ink printing can be quickly cured under ultraviolet irradiation, achieving instant drying, high printing efficiency, and UV ink has developed rapidly. However, ultraviolet light irradiation will induce the residual lignin in the bleached chemical thermomechanical pulp in the cigarette white cardboard, thereby producing methoxyl groups and generating methanol, and the methanol content will continue to increase over time.

[0003] At present, the methods to reduce the methanol content in paperboard include adjusting the pulp cooking conditions, improving the bleaching process, strengthening washing, adding adsorbents, etc. These measures undoubtedly increase the difficulty and cost of production operations.

[0004] Therefore, providing a simple and low-cost method for suppressing the release of methanol during the printing process without affecting the quality of the finished paper becomes a problem to be solved. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for reducing the methanol release of white cardboard for cigarettes. The method provided by the present invention can effectively reduce the methanol release of white cardboard for cigarettes.

[0006] The invention provides a method for reducing the methanol release of white cardboard for cigarettes, comprising: spraying a citric acid solution onto the surface of a core layer hand-sheet.

[0007] Preferably, the method for reducing the methanol release of white cigarette paper comprises the following steps:

[0008] A) respectively making a surface layer pulp, a core layer pulp and a bottom layer pulp of white cardboard to obtain a surface layer hand sheet, a core layer hand sheet and a bottom layer hand sheet;

[0009] B) spraying the citric acid solution onto the surface of the core layer hand sheet, and then compounding the surface layer hand sheet, the core layer hand sheet and the bottom layer hand sheet, pressing and drying them to obtain white card paper for cigarettes.

[0010] Preferably, the mass concentration of the citric acid solution is 0.5-2wt%.

[0011] Preferably, the spraying adopts a spray device, and the spray device has a spray diameter of 30 cm, a spray hole of 0.4 mm, a spray flow rate of 0.1 L / min, a spray pressure of 1 kg, and a spray time of 0.2 s.

[0012] Preferably, the method for preparing the core layer handsheet comprises:

[0013] mixing and diluting the bleached chemical thermomechanical pulp with water to obtain a diluted pulp;

[0014] The diluted slurry is paper-made to obtain a core layer hand sheet;

[0015] Preferably, the concentration of the diluted slurry is 1wt%;

[0016] Preferably, the papermaking amount is 120g / m 2 .

[0017] Preferably, the method for preparing the surface layer hand sheet comprises:

[0018] mixing and diluting the bleached chemical pulp with water to obtain a diluted pulp;

[0019] The diluted slurry is paper-made to obtain a surface layer hand sheet;

[0020] Preferably, the concentration of the diluted slurry is 1wt%;

[0021] Preferably, the papermaking amount is 30g / m 2 .

[0022] Preferably, the method for preparing the bottom layer hand sheet comprises:

[0023] mixing and diluting the bleached chemical pulp with water to obtain a diluted pulp;

[0024] The diluted slurry is paper-made to obtain a surface layer hand sheet;

[0025] Preferably, the concentration of the diluted slurry is 1wt%;

[0026] Preferably, the papermaking amount is 30g / m 2 .

[0027] Preferably, in step B), the pressing pressure is 350 kPa, the positive pressure is 5 min, and the reverse pressure is 2 min.

[0028] Preferably, in step B), the drying temperature is 95° C. and the drying time is 10 min.

[0029] Preferably, the core layer pulp is selected from poplar bleached chemical thermomechanical pulp or pine bleached chemical thermomechanical pulp.

[0030] Compared with the prior art, the present invention provides a method for reducing the methanol release of white cigarette paper. The present invention adopts the method of spraying a citric acid solution onto the surface of a core layer hand sheet to prepare the white cigarette paper. The method does not affect the reaction of chemical additives in the core layer slurry. In addition, the method directly sprays the citric acid solution onto the surface of the core layer hand sheet in an atomized spraying manner, and the citric acid directly contacts the core layer slurry. The method is easy to operate and can effectively reduce the methanol release of the white cigarette paper after ultraviolet drying. DETAILED DESCRIPTION

[0031] The invention provides a method for reducing the methanol release of white cardboard for cigarettes, comprising: spraying a citric acid solution onto the surface of a core layer hand-sheet.

[0032] In the present invention, the method for reducing the methanol release of white cardboard for cigarettes comprises the following steps:

[0033] A) respectively making a surface layer pulp, a core layer pulp and a bottom layer pulp of white cardboard to obtain a surface layer hand sheet, a core layer hand sheet and a bottom layer hand sheet;

[0034] B) spraying the citric acid solution onto the surface of the core layer hand sheet, and then compounding the surface layer hand sheet, the core layer hand sheet and the bottom layer hand sheet, pressing and drying them to obtain white card paper for cigarettes.

[0035] The present invention has no particular limitation on the preparation methods of the surface layer handsheet, the core layer handsheet and the bottom layer handsheet, and any method known to those skilled in the art may be used.

[0036] Wherein, the preparation method of the core layer hand sheet comprises:

[0037] mixing and diluting the bleached chemical thermomechanical pulp with water to obtain a diluted pulp;

[0038] The diluted slurry is paper-made to obtain a core layer hand sheet;

[0039] In the present invention, the core layer pulp is selected from bleached chemical thermomechanical pulp, and the bleached chemical thermomechanical pulp is selected from poplar bleached chemical thermomechanical pulp or pine bleached chemical thermomechanical pulp.

[0040] The bleached chemical thermomechanical pulp and water are placed in a fiber dispersing machine for uniform dispersion, mixing and dilution to obtain a diluted pulp, wherein the concentration of the diluted pulp is 1wt%.

[0041] Next, the diluted slurry was paper-made, and the paper-making amount was 120 g / m 2 .

[0042] The preparation method of the surface layer hand sheet comprises:

[0043] mixing and diluting the bleached chemical pulp with water to obtain a diluted pulp;

[0044] The diluted slurry is paper-made to obtain a surface layer hand sheet;

[0045] Specifically, the bleached chemical pulp and water are placed in a fiber dispersing machine for uniform dispersion, mixing and dilution to obtain a diluted pulp, wherein preferably, the concentration of the diluted pulp is 1wt%.

[0046] Next, the diluted slurry was paper-made, and the paper-making amount was 30 g / m 2 .

[0047] The preparation method of the bottom layer hand sheet comprises:

[0048] mixing and diluting the bleached chemical pulp with water to obtain a diluted pulp;

[0049] The diluted slurry is paper-made to obtain a surface layer hand sheet;

[0050] Specifically, the bleached chemical pulp and water are placed in a fiber dispersing machine for uniform dispersion, mixing and dilution to obtain a diluted pulp, wherein preferably, the concentration of the diluted pulp is 1wt%.

[0051] Next, the diluted slurry was paper-made, and the paper-making amount was 30 g / m 2 .

[0052] The present invention sprays a citric acid solution onto the surface of the core layer hand sheet. The mass concentration of the citric acid solution is 0.5-2wt%, which can be 0.5wt%, 0.7wt%, 0.9wt%, 1.0wt%, 1.2wt%, 1.4wt%, 1.5wt%, 1.7wt%, 1.9wt%, 2.0wt%, or any value between 0.5-2wt%.

[0053] The spraying adopts a spray device, the spray diameter of the spray device is 30cm, the spray hole is 0.4mm, the spray flow rate is 0.1L / min, the spray pressure is 1kg, and the spray time is 0.2s.

[0054] After the core layer hand sheet is sprayed with citric acid solution, the surface layer hand sheet, the core layer hand sheet and the bottom layer hand sheet are compounded, pressed and dried to obtain white card paper for cigarettes.

[0055] The pressing pressure is 350 kPa, the positive pressure is 5 min, and the reverse pressure is 2 min.

[0056] The drying temperature is 95° C. and the drying time is 10 min.

[0057] The present invention dries the sprayed hand sheet, cuts it into 9*5.5cm, preheats it with an ultraviolet device for 10min, and then irradiates the paper sheet with ultraviolet light for 10s. Then, the methanol content of the cigarette white cardboard is detected, and the detection method of the methanol content comprises: placing the bleached chemical thermomechanical pulp hand sheet after ultraviolet irradiation in a headspace bottle and sealing it, and using a gas chromatograph for detection, referring to the standard YC / T207-2014.

[0058] In the present invention, most cigarette paperboards only add bleached chemical thermomechanical pulp to the core layer pulp, and in the papermaking process, before the core layer and the surface layer are compounded, most of the chemicals have completed the reaction, and the addition of citric acid will not affect the reaction of chemical additives. The method provided by the present invention sprays the citric acid solution directly into the core layer pulp in an atomized spraying manner, directly contacts the core layer pulp. This method is easy to operate and can effectively reduce the release of methanol from the white cigarette paperboard after ultraviolet drying.

[0059] In order to further understand the present invention, the method for reducing the methanol release of white cardboard for cigarettes provided by the present invention is described below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0060] In the following examples and comparative examples, the poplar bleached chemical thermomechanical pulp is Crystal brand 100% poplar pulp;

[0061] The bleached pine chemical thermomechanical pulp is Xueshan brand 100% pine pulp.

[0062] Example 1

[0063] The present embodiment provides a method for reducing the methanol release of white cardboard for cigarettes, the method comprising: obtaining a citric acid diluent; papermaking a three-layer slurry of a surface, a core and a bottom; spraying the citric acid diluent evenly onto the core layer; laminating the three layers of the surface, the core and the bottom and then pressing them; drying the hand-made paper sheets and subjecting them to ultraviolet irradiation treatment; storing the hand-made paper sheets after the ultraviolet irradiation treatment in a sealed bag, and taking samples from the sealed bag on the 0th, 4th, 10th and 20th days to detect the methanol content.

[0064] Wherein, a certain amount of the citric acid is added to a certain proportion of water to obtain the citric acid dilution with a concentration of 1%wt;

[0065] The method for making core layer slurry comprises:

[0066] Add a certain amount of water to the poplar bleached chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and prepare it according to the quantitative 120g / m 2 The core layer hand sheet is obtained by papermaking.

[0067] The method for uniformly spraying the citric acid diluent onto the hand sheet comprises:

[0068] The parameters of the spraying device are as follows: spray diameter 30 cm, spray hole 0.4 mm, spray flow rate 0.1 L / min, spray pressure 1 kg, spray time 0.2 s, and the spraying is directly onto the surface of the core layer hand sheet.

[0069] The method for making the bottom slurry of the papermaking surface includes:

[0070] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0071] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0072] The ultraviolet irradiation treatment method comprises:

[0073] After the sprayed hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0074] The detection method of the methanol content comprises:

[0075] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0076] Example 2

[0077] This embodiment provides a method for reducing the methanol release of white cardboard for cigarettes, the method comprising: obtaining a citric acid diluent; making a three-layer slurry of the surface, core and bottom; spraying the citric acid diluent evenly on the core layer; laminating the three layers of the surface, core and bottom and then pressing; drying the hand-made paper sheet and subjecting it to ultraviolet irradiation treatment; placing the hand-made paper sheet after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber and sealing and storing it, and sampling from the sealed bag on the 0th, 4th, 10th and 20th day after the ultraviolet irradiation treatment is completed to detect the methanol content. Wherein, a certain amount of the citric acid is added to a certain ratio of water to obtain the citric acid diluent, with a concentration of 1%wt;

[0078] The method for making core layer slurry comprises:

[0079] Add a certain amount of water to the bleached pine chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and add a certain amount of water to the fiber disperser at 2000 rpm to disperse it evenly for 2 minutes. 2 The core layer hand sheet is obtained by papermaking.

[0080] The method for uniformly spraying the citric acid diluent onto the hand sheet comprises:

[0081] The parameters of the spraying device are spray diameter 30 cm, spray hole 0.4 mm, spray flow rate 0.1 L / min, spray pressure 1 kg, spray time 0.2 s, and the spraying is directly sprayed onto the surface of the hand sheet.

[0082] The method for making the bottom slurry of the papermaking surface includes:

[0083] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0084] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0085] The ultraviolet irradiation treatment method comprises:

[0086] After the sprayed hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0087] The detection method of the methanol content comprises:

[0088] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0089] Example 3

[0090] The present embodiment provides a method for reducing methanol release from white cardboard for cigarettes, the method comprising: obtaining a citric acid diluent; papermaking a three-layer slurry of a surface, a core and a bottom; spraying the citric acid diluent evenly onto the core layer; laminating the three layers of the surface, the core and the bottom and then pressing them; drying the hand-made paper sheets and subjecting them to ultraviolet irradiation treatment; placing the hand-made paper sheets after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber for sealed storage, and sampling and detecting the methanol content from the sealed bag on the 0th, 4th, 10th and 20th days after the ultraviolet irradiation treatment is completed.

[0091] Wherein, a certain amount of the citric acid is added to water of a certain proportion to obtain the citric acid dilution with a concentration of 0.5%wt;

[0092] The method for making core layer slurry comprises:

[0093] Add a certain amount of water to the poplar bleached chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and prepare it according to the quantitative 120g / m2 The core layer hand sheet is obtained by papermaking.

[0094] The method for uniformly spraying the citric acid diluent onto the hand sheet comprises:

[0095] The parameters of the spraying device are spray diameter 30 cm, spray hole 0.4 mm, spray flow rate 0.1 L / min, spray pressure 1 kg, spray time 0.2 s, and the spraying is directly sprayed onto the surface of the hand sheet.

[0096] The method for making the bottom slurry of the papermaking surface includes:

[0097] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0098] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0099] The ultraviolet irradiation treatment method comprises:

[0100] After the sprayed hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0101] The detection method of the methanol content comprises:

[0102] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0103] Example 4

[0104] The present embodiment provides a method for reducing methanol release from white cardboard for cigarettes, the method comprising: obtaining a citric acid diluent; papermaking a three-layer slurry of a surface, a core and a bottom; spraying the citric acid diluent evenly onto the core layer; laminating the three layers of the surface, the core and the bottom and then pressing them; drying the hand-made paper sheets and subjecting them to ultraviolet irradiation treatment; placing the hand-made paper sheets after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber for sealed storage, and sampling and detecting the methanol content from the sealed bag on the 0th, 4th, 10th and 20th days after the ultraviolet irradiation treatment is completed.

[0105] Wherein, a certain amount of the citric acid is added to water of a certain proportion to obtain the citric acid dilution with a concentration of 0.5%wt;

[0106] The method for making core layer slurry comprises:

[0107] Add a certain amount of water to the bleached pine chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and add a certain amount of water to the fiber disperser at 2000 rpm to disperse it evenly for 2 minutes. 2 The core layer hand sheet is obtained by papermaking.

[0108] The method for uniformly spraying the citric acid diluent onto the hand sheet comprises:

[0109] The parameters of the spraying device are as follows: spray diameter 30 cm, spray hole 0.4 mm, spray flow rate 0.1 L / min, spray pressure 1 kg, spray time 0.2 s, and the spraying is directly onto the surface of the core layer hand sheet.

[0110] The method for making the bottom slurry of the papermaking surface includes:

[0111] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0112] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0113] The ultraviolet irradiation treatment method comprises:

[0114] After the sprayed hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0115] The detection method of the methanol content comprises:

[0116] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0117] Example 5

[0118] The present embodiment provides a method for reducing methanol release from white cardboard for cigarettes, the method comprising: obtaining a citric acid diluent; papermaking a three-layer slurry of a surface, a core and a bottom; spraying the citric acid diluent evenly onto the core layer; laminating the three layers of the surface, the core and the bottom and then pressing them; drying the hand-made paper sheets and subjecting them to ultraviolet irradiation treatment; placing the hand-made paper sheets after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber for sealed storage, and sampling and detecting the methanol content from the sealed bag on the 0th, 4th, 10th and 20th days after the ultraviolet irradiation treatment is completed.

[0119] Wherein, a certain amount of the citric acid is added to water of a certain proportion to obtain the citric acid dilution with a concentration of 2%wt;

[0120] The method for making core layer slurry comprises:

[0121] Add a certain amount of water to the poplar bleached chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and prepare it according to the quantitative 120g / m 2 The core layer hand sheet is obtained by papermaking.

[0122] The method for uniformly spraying the citric acid diluent onto the hand sheet comprises:

[0123] The parameters of the spraying device are spray diameter 30 cm, spray hole 0.4 mm, spray flow rate 0.1 L / min, spray pressure 1 kg, spray time 0.2 s, and the spraying is directly sprayed onto the surface of the hand sheet.

[0124] The method for making the bottom slurry of the papermaking surface includes:

[0125] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0126] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0127] The ultraviolet irradiation treatment method comprises:

[0128] After the sprayed hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0129] The detection method of the methanol content comprises:

[0130] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0131] Example 6

[0132] This embodiment provides a method for reducing the methanol release of white cardboard for cigarettes, the method comprising: obtaining a citric acid diluent; making a three-layer slurry of the surface, core and bottom; spraying the citric acid diluent evenly on the core layer; laminating the three layers of the surface, core and bottom and then pressing; drying the hand-made paper sheet and subjecting it to ultraviolet irradiation treatment; placing the hand-made paper sheet after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber and sealing and storing it, and sampling from the sealed bag on the 0th, 4th, 10th and 20th day after the ultraviolet irradiation treatment is completed to detect the methanol content. Wherein, a certain amount of the citric acid is added to a certain ratio of water to obtain the citric acid diluent, with a concentration of 2%wt;

[0133] The method for making core layer slurry comprises:

[0134] Add a certain amount of water to the bleached pine chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and add a certain amount of water to the fiber disperser at 2000 rpm to disperse it evenly for 2 minutes. 2 The core layer hand sheet is obtained by papermaking.

[0135] The method for uniformly spraying the citric acid diluent onto the hand sheet comprises:

[0136] The parameters of the spraying device are spray diameter 30 cm, spray hole 0.4 mm, spray flow rate 0.1 L / min, spray pressure 1 kg, spray time 0.2 s, and the spraying is directly sprayed onto the surface of the hand sheet.

[0137] The method for making the bottom slurry of the papermaking surface includes:

[0138] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0139] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0140] The ultraviolet irradiation treatment method comprises:

[0141] After the sprayed hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0142] The detection method of the methanol content comprises:

[0143] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0144] Comparative Example 1

[0145] The comparative example provides a method for reducing the methanol release of white cardboard for cigarettes, the method comprising: making a three-layer slurry of a face, a core and a bottom; pressing the three layers of the face, the core and the bottom after compounding; drying the hand-made paper sheet and then subjecting it to ultraviolet irradiation treatment; placing the hand-made paper sheet after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber for sealed storage, and sampling from the sealed bag on the 0th, 4th, 10th and 20th day after the ultraviolet irradiation treatment is completed to detect the methanol content.

[0146] The method for making core layer slurry comprises:

[0147] Add a certain amount of water to the poplar bleached chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and prepare it according to the quantitative 120g / m 2 The core layer hand sheet is obtained by papermaking.

[0148] The method for making the bottom slurry of the papermaking surface includes:

[0149] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0150] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0151] The ultraviolet irradiation treatment method comprises:

[0152] After the hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0153] The detection method of the methanol content comprises:

[0154] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0155] Comparative Example 2

[0156] This comparative example provides a method for reducing the methanol release of white cardboard for cigarettes, the method comprising: making a three-layer slurry of a face, a core and a bottom; pressing the three layers of the face, the core and the bottom after compounding; drying the hand-made paper sheet and subjecting it to ultraviolet irradiation treatment; placing the hand-made paper sheet after the ultraviolet irradiation treatment in a sealed bag in a constant temperature and humidity chamber for sealed storage, and sampling from the sealed bag to detect the methanol content on the 0th, 4th, 10th and 20th day after the ultraviolet irradiation treatment is completed. The method for making the core layer slurry comprises:

[0157] Add a certain amount of water to the bleached pine chemical thermomechanical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and add a certain amount of water to the fiber disperser at 2000 rpm to disperse it evenly for 2 minutes. 2 The core layer hand sheet is obtained by papermaking.

[0158] The method for making the bottom slurry of the papermaking surface includes:

[0159] Add a certain amount of water to the bleached chemical pulp and place it in a fiber disperser at 2000 rpm for 2 minutes to disperse it evenly. Dilute the pulp to a concentration of 1% and adjust the amount to 30 g / m 2 Papermaking, to the surface bottom layer hand sheet.

[0160] The surface, core and bottom three layers are compounded, the pressing pressure is 350 kPa, the positive pressure is 5 minutes, the reverse pressure is 2 minutes, and the drying is carried out at 95° C. for 10 minutes to obtain the hand sheet.

[0161] The ultraviolet irradiation treatment method comprises:

[0162] After the hand sheet is dried, it is cut into 9*5.5 cm pieces, and after the ultraviolet device is preheated for 10 minutes, the paper sheet is subjected to ultraviolet irradiation for 10 seconds.

[0163] The detection method of the methanol content comprises:

[0164] The hand sheet after UV irradiation treatment is placed in a headspace bottle and sealed, and detected by gas chromatograph, referring to standard YC / T 207-2014.

[0165] Table 1 Methanol content test results data table

[0166]

[0167]

[0168] As shown in Table 1, citric acid has a significant inhibitory effect on methanol, and a higher citric acid dosage has a better inhibitory effect on methanol. Since the lignin content in pine pulp is higher than that in poplar pulp, the amount of methanol generated will be higher than that in poplar pulp. From the data, the release of methanol slows down with the extension of time, and the methanol removal ratio of poplar and pine is similar, indicating that citric acid has the same effect on inhibiting the generation of methanol for softwood pulp and hardwood pulp.

[0169] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for reducing the methanol release of white cardboard for cigarettes, characterized in that: include: Spray the citric acid solution onto the surface of the core layer hand sheet.

2. The method according to claim 1, characterized in that: The following steps are involved: A) respectively making a surface layer pulp, a core layer pulp and a bottom layer pulp of white cardboard to obtain a surface layer hand sheet, a core layer hand sheet and a bottom layer hand sheet; B) spraying the citric acid solution onto the surface of the core layer hand sheet, and then compounding the surface layer hand sheet, the core layer hand sheet and the bottom layer hand sheet, pressing and drying them to obtain white card paper for cigarettes.

3. The method according to claim 1 or 2, characterized in that: The mass concentration of the citric acid solution is 0.5-2wt%.

4. The method according to claim 1 or 2, characterized in that: The spraying adopts a spray device, the spray diameter of the spray device is 30cm, the spray hole is 0.4mm, the spray flow rate is 0.1L / min, the spray pressure is 1kg, and the spray time is 0.2s.

5. The method according to claim 1 or 2, characterized in that: The preparation method of the core layer hand sheet comprises: mixing and diluting the bleached chemical thermomechanical pulp with water to obtain a diluted pulp; The diluted slurry is paper-made to obtain a core layer hand sheet; Preferably, the concentration of the diluted slurry is 1wt%; Preferably, the papermaking amount is 120g / m 2 .

6. The method according to claim 2, characterized in that The preparation method of the surface layer hand sheet comprises: mixing and diluting the bleached chemical pulp with water to obtain a diluted pulp; The diluted slurry is paper-made to obtain a surface layer hand sheet; Preferably, the concentration of the diluted slurry is 1wt%; Preferably, the papermaking amount is 30g / m 2 .

7. The method according to claim 2, characterized in that The preparation method of the bottom layer hand sheet comprises: mixing and diluting the bleached chemical pulp with water to obtain a diluted pulp; The diluted slurry is paper-made to obtain a surface layer hand sheet; Preferably, the concentration of the diluted slurry is 1wt%; Preferably, the papermaking amount is 30g / m 2 .

8. The method according to claim 2, characterized in that: In step B), the pressing pressure is 350 kPa, the positive pressure is 5 min, and the reverse pressure is 2 min.

9. The method according to claim 2, characterized in that: In step B), the drying temperature is 95° C. and the drying time is 10 min.

10. The method according to claim 2, characterized in that The core layer pulp is selected from poplar bleached chemical thermomechanical pulp or pine bleached chemical thermomechanical pulp.

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