Preparation method of baking paper

Abstract

The invention discloses a preparation method of baking paper, and relates to the technical field of papermaking industry. According to the invention, the acidic bisulfite softwood pulp is used as a raw material, and the paper is endowed with an oil-proof characteristic through high-beating treatment, so that not only can potential harm to a human body caused by the use of an oil-proof agent in the baking paper be avoided, but also the problem of high energy consumption caused by high-beating-degree papermaking of the softwood pulp by a sulfate method in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of the paper-making industry, and particularly relates to a preparation method of baking paper. Background Art

[0002] As a kind of food-use paper, baking paper can be widely used in fields such as dessert baking, food grilling, food microwaving, and food packaging. It is a new type of healthy, environmentally friendly, and multi-functional food processing material favored by consumers. At the same time, it is also required to have comprehensive properties such as water resistance, oil resistance, non-stickiness, easy peeling, high temperature resistance, and food safety.

[0003] In the prior art, in order to meet the oil-resistant characteristics of baking paper, a separate oil-proof agent needs to be added. The oil-proof agent is mainly a fluorine-containing chemical additive. At present, due to the harm of fluorine-containing chemical additives to the human body and the environment, their use has been gradually restricted.

[0004] In addition, in order to meet the use requirements of baking paper, it is required that the fiber raw material of baking paper has a relatively high beating degree, generally above 70°SR. In order to achieve a relatively high beating degree of the raw material, a large amount of electric energy needs to be consumed during the production process of baking paper. At present, in the preparation method of baking paper, sulfate softwood pulp or a mixture of sulfate softwood pulp and sulfate hardwood pulp is mostly used, and the energy consumption during the beating process is relatively high. For example, the prior art CN 116219798 A discloses the preparation of a high-density baking base paper using unbleached sulfate softwood pulp, unbleached sulfate bamboo pulp, and unbleached sulfite softwood pulp. Although the use of sulfite softwood pulp is disclosed, the energy consumption is still relatively high when the composite pulp has a high beating degree.

[0005] Therefore, there is an urgent need to provide a preparation method of baking paper that is environmentally friendly, pollution-free, and has low energy consumption. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a preparation method of baking paper to overcome the potential harm of fluorine-containing oil-proof agents to the human body and the high energy consumption of sulfate pulp at high beating degrees in the prior art.

[0007] To achieve the above purpose, the present invention provides a preparation method of baking paper, including the following steps:

[0008] Beating acid bisulfite softwood pulp to 90 - 92°SR to obtain beaten pulp;

[0009] Adding a wet strength agent and a sizing agent to the beaten pulp to obtain sized pulp;

[0010] Making the sized pulp into paper sheets by papermaking, and subjecting the paper sheets obtained by papermaking to pressing treatment to obtain pressed paper sheets;

[0011] Drying the pressed paper sheets in a vacuum dryer;

[0012] Calender the dried paper sheet to obtain a calendered paper sheet;

[0013] Perform surface coating on the calendered paper sheet and then dry it in an oven to obtain baking paper.

[0014] The preparation method of the baking paper provided by the present invention uses acid bisulfite softwood pulp as raw material. Acid bisulfite softwood pulp is beneficial to beating of the pulp. First, more glucuronic acid is retained during cooking preparation. Second, less arabinose and xylose are retained, which is beneficial to the exposure of the S2 layer. Third, the lignin containing sulfonic groups in acid bisulfite softwood pulp has a hygroscopicity ten times greater than that of lignin containing only hydroxyl groups. The above reasons reduce the beating difficulty and energy consumption; in addition, the oil-proof property of the paper is imparted through a higher beating degree treatment, avoiding the use of oil-proof agents; it can not only avoid the potential harm to the human body caused by the use of oil-proof agents in baking paper, but also solve the problem of high energy consumption caused by high beating degree papermaking with kraft softwood pulp in the prior art. Detailed embodiments

[0015] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] The present invention provides a preparation method of baking paper, including the following steps:

[0017] Beat the acid bisulfite softwood pulp to 90°SR to obtain beaten pulp;

[0018] Add wet strength agent and sizing agent to the beaten pulp to obtain sized pulp;

[0019] Form the sized pulp, and perform pressing on the formed paper sheet to obtain a pressed paper sheet;

[0020] Dry the pressed paper sheet in a vacuum dryer to obtain a dried paper sheet;

[0021] Calender the dried paper sheet to obtain a calendered paper sheet;

[0022] Perform surface coating on the calendered paper sheet and then dry it in an oven to obtain baking paper.

[0023] First, the acidic bisulfite softwood pulp in the present invention is beaten to 90 - 92°SR to obtain beaten pulp. In the present invention, softwood pulp is the pulp obtained after the dissociation of softwood fiber raw materials through the pulping process. The acidic bisulfite softwood pulp in the present invention is obtained by cooking plant fiber raw materials with bisulfite cooking liquor, so that most of the lignin in the raw materials is dissolved and the fibers in the raw materials are separated from each other; controlling the pH of the bisulfite cooking liquor to be acidic can prepare acidic bisulfite softwood pulp; the pH of the bisulfite cooking liquor in the present invention is preferably 1.5 - 2 at room temperature; the bisulfite in the present invention is preferably sodium bisulfite or calcium bisulfite. The present invention has no special requirements for plant fiber raw materials, and softwood can be used. The reasons for using acidic bisulfite softwood pulp in the present invention are as follows: 1. More glucuronic acid is retained during cooking and preparation; 2. Less arabinose and xylose are retained, which is beneficial to the exposure of the S2 layer; 3. The lignin containing sulfonic acid groups in acidic bisulfite softwood pulp has a hygroscopicity ten times greater than that of lignin containing only hydroxyl groups. Therefore, using acidic bisulfite softwood pulp can reduce the beating difficulty and energy consumption.

[0024] In the present invention, the equipment for beating is preferably a Valley beater; the concentration of beating is preferably 1.55 - 1.60%, the time of beating is preferably 90 - 150 min, and the counterweight is preferably a 3 kg weight. In the present invention, the beating degree of beating is preferably 90 - 92°SR. The beating degree of existing kraft softwood pulp is generally 40 - 70°SR. The present invention endows the paper with oil-proof properties through higher beating degree treatment, avoiding the use of oil-proof agents; it can not only avoid the potential harm caused by the use of oil-proof agents in baking paper to the human body, but also solve the problem of high energy consumption caused by high beating degree papermaking of kraft softwood pulp in the prior art. The present invention has no special limitations on the equipment and parameters of the beating process, and conventional equipment and parameters in the art can be used.

[0025] After obtaining the beaten pulp, the present invention adds a wet strength agent and a sizing agent to the beaten pulp to obtain a formulated pulp. In the present invention, the wet strength agent is preferably polyamide epichlorohydrin resin, and based on the amount of absolute dry pulp, the dosage of the wet strength agent is preferably 1 - 2%; and / or, the sizing agent is preferably one or more of alkyl ketene dimer, rosin size, and alkenyl succinic anhydride, and based on the amount of absolute dry pulp, the dosage of the sizing agent is preferably 0.05 - 0.3%. It should be understood that the amount based on absolute dry pulp in the present invention refers to the ratio of the absolute dry amount of the wet strength agent to the absolute dry amount of the fiber. It should be understood that after adding the wet strength agent and the sizing agent to the beaten pulp, the present invention also includes appropriately stirring the pulp. The present invention has no special limitations on the intensity of the stirring, and it is appropriate.

[0026] After obtaining the furnish pulp, the present invention forms the furnish pulp into a paper sheet, and the formed paper sheet is subjected to pressing treatment to obtain the pressed paper sheet. In the present invention, the forming is preferably carried out using a paper former; and / or, the pressure of the pressing is preferably 250 - 350 kPa, and the time of the pressing is preferably 0.5 - 2 min.

[0027] Preferably, after the pressing treatment and before the calendering treatment, the present invention further includes: drying the pressed paper sheet to obtain a dried paper sheet. In the present invention, the drying is preferably carried out using a vacuum dryer, the temperature of the drying is preferably 95 - 105 °C, and the time is preferably 8 - 12 min.

[0028] After obtaining the pressed paper sheet, the present invention subjects the pressed paper sheet to calendering treatment to obtain a calendered paper sheet. In the present invention, the pressure of the calendering treatment is preferably 5 kgf, and each side is calendered once.

[0029] Preferably, after the calendering treatment, the present invention further includes: drying using a drum dryer. Among them, the temperature of the drying is preferably 100 - 120 °C, and the time of the drying is preferably 2 - 10 min.

[0030] After obtaining the calendered paper sheet, the present invention subjects the calendered paper sheet to surface coating treatment, and then dries it in an oven to obtain baking paper. In the present invention, the surface coating treatment is preferably carried out using an organosilicon release agent, and the coating amount is preferably 0.2 - 2 g / m 2 . In the present invention, the temperature of the oven drying is preferably 120 - 160 °C, and the time is preferably 1 - 3 min.

[0031] To better illustrate the technical solution of the present invention, the present invention also provides the following specific examples. It should be understood that the raw materials used in the following examples are all commercially available raw materials unless otherwise specified.

[0032] Example 1

[0033] S1. The acid bisulfite softwood pulp is beaten to 90° SR with a Valley beater, the beating consistency is 1.57%, and the weight is 3 kg weight, to obtain the beaten pulp;

[0034] S2. Add 1.5% of polyamide epichlorohydrin resin (wet strength agent, based on the amount of absolute dry pulp) and 0.1% of alkyl ketene dimer (sizing agent, based on the amount of absolute dry pulp) to the beaten pulp to obtain the furnish pulp;

[0035] S3. The furnish pulp is formed into a paper sheet using a paper former, and the formed paper sheet is pressed at a pressure of 300 kPa for 1 min to obtain the pressed paper sheet;

[0036] S4. Dry the pressed paper sheet in a vacuum dryer at 100 °C for 8 min;

[0037] S5. Calender the dried paper sheet. The pressure for calendering is 5 kgf, and calender each side once to obtain the calendered paper sheet;

[0038] S6. Perform surface coating on the calendered paper sheet. The surface coating is carried out with a silicone release agent, and the coating amount is 1 g / m 2 , and then dry in an oven at 140 °C for 2 min to obtain baking paper.

[0039] Testing the obtained baking paper shows that: beating time is 115 min, basis weight (weight of paper) is 40 g / m 2 , bulk (density of paper) is 1.0 g / cm 3 , water absorbency Cobb (60 s) is 10 g / m 2 , oil resistance kit value is 3, 180° peel strength is 1 N.

[0040] Example 2

[0041] S1. Beat acid bisulfite softwood pulp with a Valley beater to a beating degree of 91° SR for 120 min. The beating consistency is 1.55%, and the counterweight is a 3 kg weight to obtain beaten pulp;

[0042] S2. Add 1% polyamide epichlorohydrin resin (wet strength agent, based on the amount of absolute dry pulp) and 0.3% rosin size (sizing agent, based on the amount of absolute dry pulp) to the beaten pulp to obtain sized pulp;

[0043] S3. Sheet the sized pulp with a sheet former, and press the sheet obtained from sheeting at a pressure of 250 kPa for 2 min to obtain the pressed paper sheet;

[0044] S4. Dry the pressed paper sheet in a vacuum dryer at 105 °C for 10 min;

[0045] S4. Calender the dried paper sheet. The pressure for calendering is 5 kgf, and calender each side once to obtain the calendered paper sheet;

[0046] S5. Perform surface coating on the calendered paper sheet. The surface coating is carried out with a silicone release agent, and the coating amount is 0.2 g / m 2 , and then dry in an oven at 120 °C for 3 min to obtain baking paper.

[0047] Testing the obtained baking paper shows that: beating time is 120 min, basis weight is 40 g / m 2 , bulk is 1.1 g / cm 3, water absorbency Cobb (60s) 10 g / m 2 , oil resistance kit value 4, 180° peel strength 0.8 N.

[0048] Example 3

[0049] S1. Beat the acid bisulfite softwood pulp with a Valley beater to 92° SR, the beating consistency is 1.60%, the counterweight is 3 kg weight, and the beaten pulp is obtained;

[0050] S2. Add 2% polyamide epichlorohydrin resin (wet strength agent, based on the amount of absolute dry pulp) - 0.3% alkenyl succinic anhydride (sizing agent, based on the amount of absolute dry pulp) to the beaten pulp to obtain the mixed pulp;

[0051] S3. Sheet the mixed pulp with a sheet former, press the sheet obtained from sheeting for 0.5 min under a pressure of 350 kPa to obtain the pressed sheet; dry the pressed sheet at 95 °C for 12 min to obtain the dried sheet;

[0052] S4. Calender the dried sheet, the pressure for calendering is 5 kgf, calender both sides once to obtain the calendered sheet; dry the calendered sheet with a drum dryer, the drying temperature is 20 °C, and the drying time is 5 min;

[0053] S5. Surface coat the calendered sheet, the surface coating is carried out with a silicone release agent, and the coating amount is 2 g / m 2 , and then dry in an oven at 160 °C for 1 min to obtain baking paper.

[0054] Testing the obtained baking paper shows that: beating time 150 min, basis weight 40 g / m 2 , density 1.08 g / cm 3 , water absorbency Cobb (60s) 9 g / m 2 , oil resistance kit value 5, 180° peel strength 0.7 N.

[0055] Comparative Example

[0056] In the comparative example, the acid bisulfite softwood pulp in Example 3 was replaced with sulfate softwood pulp, and the beating degree was set to 75° SR, with other conditions remaining unchanged.

[0057] Testing the obtained baking paper shows that: beating time 150 min, basis weight 40 g / m 2 , density 0.9 g / cm 3 , water absorbency Cobb (60s) 12 g / m 2 , oil resistance kit value 0, 180° peel strength 1 N.

[0058] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of baking paper, characterized in that, It includes the following steps: Beating softwood acid bisulfite pulp to 90 - 92°SR to obtain beaten pulp; Adding a wet strength agent and a sizing agent to the beaten pulp to obtain sized pulp; Making the sized pulp by papermaking, and subjecting the formed paper sheet to pressing to obtain a pressed paper sheet; Drying the pressed paper sheet in a vacuum dryer to obtain a dried paper sheet; Calendering the dried paper sheet to obtain a calendered paper sheet; Performing surface coating on the calendered paper sheet, and then drying it in an oven to obtain baking paper.

2. The preparation method according to claim 1, characterized in that, The concentration of the beating is 1.55 - 1.60%, the beating time is 90 - 150 min, and the counterweight is a 3 kg weight.

3. The preparation method according to claim 1, wherein, The wet strength agent is polyamide epichlorohydrin resin, and based on the amount of absolutely dry pulp, the dosage of the wet strength agent is 1 - 2%; and / or, The sizing agent is one or more of alkyl ketene dimer, rosin size, and alkenyl succinic anhydride, and based on the amount of absolutely dry pulp, the dosage of the sizing agent is 0.05 - 0.3%.

4. The preparation method according to claim 1, characterized in that, The papermaking is carried out using a paper former; and / or, The pressure of the pressing is 250 - 350 kPa, and the pressing time is 0.5 - 2 min.

5. The preparation method according to claim 1, characterized in that, The drying temperature in the vacuum dryer is 95 - 105 °C, and the drying time is 8 - 12 min.

6. The preparation method according to claim 1, characterized in that, The pressure of the calendering treatment is 5 kgf, and each side is calendered once.

7. The preparation method according to claim 1 or 6, characterized in that, After the calendering treatment, it further includes: drying using a drum dryer; Wherein, the drying temperature is 100 - 120 °C, and the drying time is 2 - 10 min.

8. The preparation method according to claim 1, characterized in that, The surface coating treatment is carried out with a silicone release agent, and the coating amount is 0.2 - 2 g / m 2 .

9. The preparation method according to claim 1, characterized in that, The drying temperature in the oven is 120 - 160 °C, and the drying time is 1 - 3 min.