Novel insulation paper and preparation method thereof

Abstract

The invention discloses novel insulation paper and a preparation method thereof. The novel insulation paper comprises the following raw materials in parts by weight: 60-65 parts of flame-retardant bamboo pulp; 15-20 parts of waste paper regenerated fiber; 8 to 10 parts of modified montmorillonite; 5-8 parts of a zinc borate compound; 3-5 parts of glycerol ester of rosin; 1 to 2 parts of polyvinyl butyral; the invention relates to the technical field of insulation paper. According to the novel insulation paper and the preparation method thereof, through cooperation of the flame-retardant bamboo pulp, the waste paper regenerated fibers, the modified montmorillonite, the zinc borate compound, the rosin glyceride and the polyvinyl butyral, the low-cost requirement is ensured by utilizing regenerated materials, the breakdown field strength of the insulation paper is improved, the thermal aging life of the insulation paper is prolonged, and the limit oxygen index of the insulation paper is increased; the insulation paper has the advantages that the insulation paper is simple in structure, use reliability is guaranteed, the problems that natural fiber insulation paper is prone to moisture absorption and low in strength are solved, good flame retardance and surface hydrophobicity are achieved, and effective support is provided for light-weight and high-efficiency development of transformers.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating paper, in particular to a novel insulating paper and a preparation method thereof. Background Art

[0002] As the core equipment of the power system, the performance of the insulation system of the transformer directly determines the operating reliability and service life of the equipment. Traditional transformer insulation materials are mainly divided into two categories: One type is synthetic fiber materials, represented by aramid paper. Although they have excellent temperature resistance and electrical properties, the high price of raw materials leads to high equipment manufacturing costs. The other type is natural fiber materials represented by ordinary cellulose insulation paper, such as cable paper and telephone paper. Although they are low in cost, their thermal stability temperature is generally lower than 105°C, which makes it difficult to meet the requirements of new transformers to increase load density.

[0003] In addition, existing modification technologies mostly focus on improving a single performance, such as improving the flame retardancy or mechanical strength of materials by adding flame retardants or nanofillers, but lack innovation at the material system level, especially in balancing environmental performance and cost control. There are obvious shortcomings. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a new type of insulating paper and a preparation method thereof, which solves the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A new type of insulating paper, the raw materials of which include, by weight: Flame retardant bamboo pulp: 60-65 parts; Waste paper recycled fiber: 15-20 parts; Modified montmorillonite: 8-10 parts; Zinc borate complex: 5-8 parts; Rosin glycerol ester: 3-5 parts; Polyvinyl butyral: 1 to 2 parts.

[0006] The present invention is further configured as follows: the raw materials include, by weight: Flame retardant bamboo pulp: 60 parts; Waste paper recycled fiber: 20 parts; Modified montmorillonite: 8 parts; Zinc borate complex: 5 parts; Rosin glycerol ester: 3 parts; Polyvinyl butyral: 1 part.

[0007] The present invention is further configured as follows: the raw materials include, by weight: Flame retardant bamboo pulp: 63 parts; Waste paper recycled fiber: 18 parts; Modified montmorillonite: 9 parts; Zinc borate complex: 7 parts; Rosin glycerol ester: 4 parts; Polyvinyl butyral: 1 part.

[0008] The present invention is further configured as follows: the raw materials include, by weight: Flame retardant bamboo pulp: 65 parts; Waste paper recycled fiber: 15 parts; Modified montmorillonite: 10 parts; Zinc borate complex: 8 parts; Rosin glycerol ester: 5 parts; Polyvinyl butyral: 2 parts.

[0009] The present invention also discloses a method for preparing a novel insulating paper, which specifically comprises the following steps: Step 1: flame-retardant bamboo pulp, waste paper recycled fiber, modified montmorillonite, zinc borate complex, rosin glycerol ester and polyvinyl butyral are sequentially fed into a twin-screw extruder at a feed end temperature of 60° C., a discharge end temperature of 85° C., and a mixing time of 8 to 10 minutes to obtain a slurry; Step 2: Adjust the slurry concentration to 0.8-1.2wt%, add 0.8wt% of dispersant, the dispersant is composed of sodium lignin sulfonate and polyethylene oxide in a mass ratio of 1:0.3; Step 3: Papermaking is carried out using a Fourdrinier paper machine at a speed of 50 to 80 m / min, an initial pressing pressure of 0.5 MPa, a secondary pressing pressure of 2.0 MPa, a drying and preheating section of 80° C., a main drying section of 105° C., and a cooling section of 60° C. to obtain a semi-finished insulating paper product; Step 4: Pre-press the semi-finished insulating paper at 120° C. for 5 minutes with a pressure of 2.0 MPa, then press at 160° C. for 15 minutes with a pressure of 2.0 MPa, and then slowly cool at 140° C. for 10 minutes with a pressure of 2.0 MPa to obtain insulating paper.

[0010] The present invention provides a novel insulating paper and a preparation method thereof. It has the following beneficial effects: The present invention utilizes flame-retardant bamboo pulp, waste paper recycled fiber, modified montmorillonite, zinc borate complex, rosin glycerol ester and polyvinyl butyral to ensure low cost by utilizing recycled materials, thereby improving the breakdown field strength of the insulating paper, and increasing the thermal aging life and limiting oxygen index of the insulating paper to ensure reliability in use. The present invention solves the problems of easy moisture absorption and low strength of natural fiber insulating paper, has good flame retardancy and surface hydrophobicity, and provides effective support for the development of lightweight and efficient transformers. DETAILED DESCRIPTION

[0011] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0012] The embodiments of the present invention provide the following technical solutions: Example 1 A new type of insulating paper, the raw materials of which include, by weight: Flame retardant bamboo pulp: 60 parts. The preparation method of flame retardant bamboo pulp includes: Two-year-old bamboo was sliced ​​and steamed at 160°C for 90 minutes in 18% to 22% NaOH. The pulp was then washed in countercurrent until the pH was less than 9. Impurities were removed by pressure screening with a 0.15mm sieve gap to obtain flame-retardant bamboo pulp. XPS analysis showed that the Si content was 1.2-1.8wt%, indicating that this processing method retains the natural SiO2 deposition layer, providing reliable support for improving the flame retardancy of insulation paper. Waste paper recycled fiber: 20 parts. Waste paper recycled fiber is made from deinked office paper pulp, processed by a heat disperser, and then ground to 35°SR by a double-disc mill with a gap of 0.15mm to ensure that the average fiber length is 2.1-2.5mm; Modified montmorillonite: 8 parts. The preparation method of the modified montmorillonite includes: Sodium montmorillonite was dispersed in deionized water and stirred at 60°C for 2 h to obtain a 2 wt% suspension. Add 1.2 times the mass of sodium montmorillonite cetyltrimethylammonium bromide, heat to 70°C, and stir at 300 rpm for 4 h; After centrifugal washing, the mixture was dried at 80°C to constant weight and crushed through a 200-mesh sieve to obtain modified montmorillonite; Zinc borate complex: 5 parts. The preparation method of the zinc borate complex includes: Prepare a mixed solution of zinc nitrate and boric acid in a molar ratio of 3:1; Add 0.3 M hydroxyapatite suspension dropwise and hydrothermally react at 80 °C for 6 h; After aging for 12 h, centrifugal washing, drying at 105 °C, and air flow milling to D50 = 1.2 μm; Rosin glycerol ester: 3 parts. The preparation method of rosin glycerol ester includes: 0.5 wt% sulfuric acid was added to rosin and glycerol in a molar ratio of 1:1.2, and the reaction was carried out in a vacuum at 220°C for 4 h; 3 wt% activated clay was used for decolorization, and after deodorization at 150°C for 30 min, rosin glycerol ester was obtained by filtering through a 200-mesh sieve; Polyvinyl butyral: 1 part, polyvinyl butyral is Mowital B30H industrial grade PVB.

[0013] The preparation method of the insulating paper comprises: Step 1: flame-retardant bamboo pulp, waste paper recycled fiber, modified montmorillonite, zinc borate complex, rosin glycerol ester and polyvinyl butyral are sequentially put into a twin-screw extruder at a feed end temperature of 60° C., a discharge end temperature of 85° C., and a mixing time of 8 minutes to obtain a slurry; Step 2: Adjust the slurry concentration to 1.2 wt% and add 0.8 wt% of a dispersant, wherein the dispersant is composed of sodium lignin sulfonate and polyethylene oxide in a mass ratio of 1:0.3; Step 3: Papermaking is carried out using a Fourdrinier paper machine at a speed of 80 m / min, an initial pressing pressure of 0.5 MPa, a secondary pressing pressure of 2.0 MPa, a drying and preheating section of 80° C., a main drying section of 105° C., and a cooling section of 60° C. to obtain a semi-finished insulating paper product; Step 4: Pre-press the semi-finished insulating paper at 120° C. for 5 minutes with a pressure of 2.0 MPa, then press at 160° C. for 15 minutes with a pressure of 2.0 MPa, and then slowly cool at 140° C. for 10 minutes with a pressure of 2.0 MPa to obtain insulating paper.

[0014] Example 2 The difference between this embodiment and embodiment 1 is that: a new type of insulating paper, the raw materials of which include, by weight: Flame retardant bamboo pulp: 63 parts; Waste paper recycled fiber: 18 parts; Modified montmorillonite: 9 parts; Zinc borate complex: 7 parts; Rosin glycerol ester: 4 parts; Polyvinyl butyral: 1 part.

[0015] The preparation method of the insulating paper comprises: Step 1: flame-retardant bamboo pulp, waste paper recycled fiber, modified montmorillonite, zinc borate complex, rosin glycerol ester and polyvinyl butyral are sequentially put into a twin-screw extruder at a feed end temperature of 60° C., a discharge end temperature of 85° C., and a mixing time of 9 minutes to obtain a slurry; Step 2: Adjust the slurry concentration to 1.0 wt% and add 0.8 wt% of a dispersant, wherein the dispersant is composed of sodium lignin sulfonate and polyethylene oxide in a mass ratio of 1:0.3; Step 3: Papermaking is carried out using a Fourdrinier paper machine at a speed of 60 m / min, an initial pressing pressure of 0.5 MPa, a secondary pressing pressure of 2.0 MPa, a drying and preheating section of 80° C., a main drying section of 105° C., and a cooling section of 60° C. to obtain a semi-finished insulating paper product; Step 4: Pre-press the semi-finished insulating paper at 120° C. for 5 minutes with a pressure of 2.0 MPa, then press at 160° C. for 15 minutes with a pressure of 2.0 MPa, and then slowly cool at 140° C. for 10 minutes with a pressure of 2.0 MPa to obtain insulating paper.

[0016] Example 3 The difference between this embodiment and embodiment 1 is that: a new type of insulating paper, the raw materials of which include, by weight: Flame retardant bamboo pulp: 65 parts; Waste paper recycled fiber: 15 parts; Modified montmorillonite: 10 parts; Zinc borate complex: 8 parts; Rosin glycerol ester: 5 parts; Polyvinyl butyral: 2 parts.

[0017] The preparation method of the insulating paper comprises: Step 1: flame-retardant bamboo pulp, waste paper recycled fiber, modified montmorillonite, zinc borate complex, rosin glycerol ester and polyvinyl butyral are sequentially put into a twin-screw extruder at a feed end temperature of 60° C., a discharge end temperature of 85° C., and a mixing time of 10 minutes to obtain a slurry; Step 2: Adjust the slurry concentration to 0.8wt% and add 0.8wt% of a dispersant, wherein the dispersant is sodium lignin sulfonate and polyethylene oxide in a mass ratio of 1:0.3; Step 3: Papermaking is carried out using a Fourdrinier paper machine at a speed of 50 m / min, an initial pressing pressure of 0.5 MPa, a secondary pressing pressure of 2.0 MPa, a drying and preheating section at 80° C., a main drying section at 105° C., and a cooling section at 60° C. to obtain a semi-finished insulating paper product; Step 4: Pre-press the semi-finished insulating paper at 120° C. for 5 minutes with a pressure of 2.0 MPa, then press at 160° C. for 15 minutes with a pressure of 2.0 MPa, and then slowly cool at 140° C. for 10 minutes with a pressure of 2.0 MPa to obtain insulating paper.

[0018] It is further explained that in order to improve the hydrophobic properties of the insulating paper, a roller coating process is used to coat the surface of the insulating paper with a prepared nano-SiO2 sol with a solid content of 15wt% and a pH of 9.0. At the same time, 0.2wt% polydimethylsiloxane is added as a leveling agent, and the coating thickness is controlled to 0.3-0.5μm. The paper is then cured with hot air at 120°C for 30s.

[0019] In summary, the present invention provides a nano barrier layer by modifying montmorillonite. Cone calorimeter testing found that CO2 release was reduced by 40%, the zinc borate complex synergistically flame retardant in the gas phase and the condensed phase, and the total heat release was reduced by 35%. The native SiO2 layer in the flame-retardant bamboo pulp was used as the flame-retardant skeleton of the base material to improve the flame retardancy. Rosin glycerol ester formed hydrogen bonds with the hydroxyl groups on the fiber surface, and the contact angle was increased by 32°, thereby improving the surface hydrophobicity. The nano-SiO2 coating was used to construct a hydrophobic barrier with a water contact angle of 110°-115°. The modified montmorillonite sheets formed an intercalated structure with the fibers to improve the tensile strength. The zinc borate nanoparticles filled the gaps between the fibers to further improve the tear resistance.

[0020] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A new type of insulating paper, characterized in that: The raw materials include by weight: Flame retardant bamboo pulp: 60-65 parts; Waste paper recycled fiber: 15-20 parts; Modified montmorillonite: 8-10 parts; Zinc borate complex: 5-8 parts; Rosin glycerol ester: 3-5 parts; Polyvinyl butyral: 1 to 2 parts.

2. The novel insulating paper according to claim 1, characterized in that: The preparation method of the flame retardant bamboo pulp comprises: Two-year-old bamboo was selected, sliced, and steamed at 160°C for 90 minutes in NaOH with a concentration of 18% to 22%. The pulp was washed in countercurrent until the pH value was less than 9. The pulp was sieved with a pressure screen with a sieve gap of 0.15 mm to remove impurities and obtain flame-retardant bamboo pulp.

3. The novel insulating paper according to claim 1, characterized in that: The length of the waste paper recycled fiber is 2.1-2.5 mm.

4. The novel insulating paper according to claim 1, characterized in that: The preparation method of the modified montmorillonite comprises: Sodium montmorillonite was dispersed in deionized water and stirred at 60°C for 2 h to obtain a 2 wt% suspension. Add 1.2 times the mass of sodium montmorillonite cetyltrimethylammonium bromide, heat to 70°C, and stir at 300 rpm for 4 h; After centrifugal washing, the product was dried at 80°C to a constant weight, and pulverized to pass through a 200-mesh sieve to obtain modified montmorillonite.

5. The novel insulating paper according to claim 1, characterized in that: The preparation method of the zinc borate complex comprises: Prepare a mixed solution of zinc nitrate and boric acid in a molar ratio of 3:1; Add 0.3M hydroxyapatite suspension dropwise and hydrothermally react at 80°C for 6 h; After aging for 12 hours, centrifugal washing, drying at 105°C, and air flow milling to D50 = 1.2 μm.

6. The novel insulating paper according to claim 1, characterized in that: The preparation method of the rosin glycerol ester comprises: 0.5 wt% sulfuric acid was added to rosin and glycerol in a molar ratio of 1:1.2, and the reaction was carried out in a vacuum at 220°C for 4 h; The rosin glycerol ester was obtained by decolorization with 3 wt% activated clay and deodorization at 150°C for 30 min and filtering through a 200-mesh sieve.

7. The novel insulating paper according to claim 1, characterized in that: The polyvinyl butyral is Mowital B30H industrial grade PVB.

8. A method for preparing a novel insulating paper, characterized in that: The specific steps include: Step 1: flame-retardant bamboo pulp, waste paper recycled fiber, modified montmorillonite, zinc borate complex, rosin glycerol ester and polyvinyl butyral are sequentially fed into a twin-screw extruder at a feed end temperature of 60° C., a discharge end temperature of 85° C., and a mixing time of 8 to 10 minutes to obtain a slurry; Step 2: Adjust the slurry concentration to 0.8-1.2wt%, add 0.8wt% of dispersant, the dispersant is composed of sodium lignin sulfonate and polyethylene oxide in a mass ratio of 1:0.3; Step 3: Papermaking is carried out using a Fourdrinier paper machine at a speed of 50 to 80 m / min, an initial pressing pressure of 0.5 MPa, a secondary pressing pressure of 2.0 MPa, a drying and preheating section of 80° C., a main drying section of 105° C., and a cooling section of 60° C. to obtain a semi-finished insulating paper product; Step 4: Pre-press the semi-finished insulating paper at 120° C. for 5 minutes with a pressure of 2.0 MPa, then press at 160° C. for 15 minutes with a pressure of 2.0 MPa, and then slowly cool at 140° C. for 10 minutes with a pressure of 2.0 MPa to obtain insulating paper.