Preparation method of inorganic fiber carrier for ignition paper

Abstract

The invention discloses a preparation method of an inorganic fiber carrier for ignition paper, and belongs to the technical field of preparation of ignition paper for thermal batteries. The inorganic fiber carrier for the ignition paper is prepared by adopting non-asbestos inorganic fibers as raw materials and sequentially carrying out fiber beating, purification, pH regulation and a wet-process special paper process, and has no oxidation or oxidation performance. The non-asbestos inorganic fiber is adopted to replace a traditional asbestos material, so that the harm of traditional asbestos dust is reduced; the inorganic fiber papermaking carrier has better loosening and dispersing performance in water and has good retention, adsorption and retention effects on oxidizing agent and reducing agent particles, the thickness of the obtained inorganic fiber carrier is 0.2-0.05 mm, the tightness is smaller than or equal to 0.7 g / cm < 3 >, the longitudinal tensile strength is larger than or equal to 0.20 kN / m, and the tensile strength is larger than or equal to 0.20 kN / m. The thermal battery ignition paper prepared by the method has the characteristics of high uniformity, high bonding strength, small pore-forming aperture, high chemical agent adsorption capacity, high chemical stability and the like, fibers of the thermal battery ignition paper are not wound in water, the debonding degree is qualified, and the thermal battery ignition paper can meet the use requirements of the thermal battery ignition paper.

Description

Technical Field

[0001] The present invention belongs to the technical field of ignition paper materials in a thermal battery activation system, and particularly relates to a preparation method of a thermal battery ignition paper matrix, that is, an inorganic fiber carrier for ignition paper. Background Art

[0002] A thermal battery is a reserve battery with molten salt as the electrolyte and is activated by its own heat source to melt it. Its operating temperature is 350°C to 550°C. The thermal battery uses some alkali metals with small atomic weights and active chemical properties (such as lithium, sodium, calcium, etc.) as the negative electrode material, and has a very high specific power and specific energy. Due to the advantages of short activation time, wide operating ambient temperature, and long storage period, etc., this power supply system is more and more widely used in special power supply systems.

[0003] Thermal battery working principle: When the battery works, an external electrical signal or mechanical force is used to make the igniter inside the battery ignite. The fire source is guided to the heating sheet inside the battery through the ignition paper. The heating sheet burns, making the single battery reach its operating temperature, heating the solid electrolyte that is not conductive at room temperature into a molten ionic conductor. The anode and cathode materials undergo oxidation-reduction reactions through the molten electrolyte to generate electrical energy. Therefore, the ignition paper is an extremely important component in the thermal battery working system, and its preparation quality determines whether the thermal battery can be successfully activated and the length of the thermal battery activation time.

[0004] The preparation method of the ignition paper uses an inorganic fiber material as the carrier, adds powdery chemical drugs such as highly active oxidants and reductants to the slurry containing inorganic fibers, and adopts a wet papermaking process method, and is made through processes such as dehydration by a metal filter screen, suction filtration, and drying. The inorganic fiber material mainly serves as the carrier for the oxidant and reductant and does not participate in the chemical reactions therein.

[0005] Since the thermal battery stack is installed in a closed metal casing, to ensure the safety of the thermal battery, it is required that the inorganic carrier material for preparing the ignition paper has as little gas evolution as possible, has good bonding strength, has good retention of reaction drug particles, and has good dispersion performance in water.

[0006] Currently, the carrier materials for preparing the ignition paper mainly include loosened asbestos paper and a small amount of glass wool paper for air filtration. The loosened asbestos paper is made from asbestos inorganic fibers as raw materials and is made by a wet special paper process after beating treatment. Analyzed from the technical indicators, the loosened asbestos paper has a relatively high ignition loss rate and no strength index, which affects the stability and durability of the material under stress; another problem is that asbestos dust is harmful to human lung diseases and has a great impact on the operators. Many countries have ordered to ban the use of asbestos and related products, and it has also been proposed in China to gradually phase out asbestos products. Therefore, it is particularly important to prepare a new type of carrier material. Summary of the Invention

[0007] Aiming at the technical problems existing in the prior art, the purpose of the present invention is to provide a preparation method for an inorganic carrier of ignition paper for thermal batteries. The above object of the present invention is achieved through the following technical solutions: An inorganic carrier of ignition paper for thermal batteries, which is made of inorganic fibers as raw materials, processed through a beating process and a purification process, adding a pH regulator for the slurry, and made by a wet special paper process. The obtained carrier material has higher bonding strength, lower ignition loss rate, and higher retention rate for chemical drugs.

[0008] The preparation method of the inorganic fiber carrier for preparing the ignition paper used in the present invention uses inorganic fibers as raw materials, and is successively made through fiber beating, purification, pH adjustment and wet special paper process, specifically including the following steps: S1: Put the inorganic fibers into a beater, add water until the beating concentration is 2.0% - 3.5%, and loosen the fibers to single fibers in the beater, and beat to a fiber slurry with a beating degree of 60 - 90°SR and a wet weight of 1 - 30 g; S2: Purify the fiber slurry in step S1, and perform centrifugal sand removal treatment with a conical desander in a wet sand removal method; S3: According to needs, add water to the slurry in step S2 to adjust the pulp concentration to a certain level, and then add acid or alkali to adjust the pH to 7 - 9, that is, adjust the pH value to neutral to weakly alkaline; S4: Use a wet special paper making equipment to make the slurry in step S3 into an inorganic fiber loose paper, which is the inorganic carrier material.

[0009] Preferably, the inorganic fibers are non-asbestos inorganic fibers and do not contain impurities such as grit, crystal bundles, and dust. The inorganic fiber raw materials include a mixture of 90wt% - 100wt% of one or more of wollastonite fiber, palygorskite fiber, sepiolite fiber, brucite fiber, ceramic fiber cotton, high-alumina polycrystalline fiber, and mullite fiber and 0 - 10wt% of glass fiber.

[0010] Further preferably, in step S1, the inorganic fibers are fibrillated by a beater for pulp and paper making, and after beating, the wet weight is 2 - 15 g; Preferably, the purification and sand removal process is a wet sand removal method, and a conical desander and other equipment are used for centrifugal sand removal. The sand removal pulp concentration of the inorganic fibers in step S2 is 0.5 - 3.0%.

[0011] Preferably, the alkali in the pH regulator is caustic soda, liquid caustic soda, potassium hydroxide or lime water, etc., and the acid is oxalic acid, acetic acid, salicylic acid, acetic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, etc., organic acids or inorganic acids, and the pH of the slurry is adjusted to 7 - 9 with the acid-base pH regulator.

[0012] Preferably, in step S3, the papermaking pulp is mixed with water to a concentration of 0.1% to 0.8%.

[0013] The inorganic carrier material prepared by the process defined in the present invention has a thickness of 0.2 ± 0.05 mm, a bulk density ≤ 0.7 g / cm 3 , a longitudinal tensile strength ≥ 0.20 kN / m, and does not have the property of oxidation or being oxidized, and its ignition loss ≤ 10% (600 °C, 15 min).

[0014] By adopting the above technologies, compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention uses non-asbestos inorganic fiber raw materials, which are more environmentally friendly and reduce the impact of traditional asbestos fiber dust on the lungs of workers, meeting the requirements of labor protection; 2. During the preparation of the inorganic fiber carrier of the present invention, by defining specific beating conditions, such as beating time, beating degree, wet weight, etc., while ensuring a high retention rate, corresponding strength can also be achieved, avoiding the problem that when the beating degree of the fiber is too high, the fiber will be cut off, reducing the strength of the carrier material, or when the beating degree of the fiber is too low, the faster the filtration rate of the pulp, and the lower the retention rate of the oxidant and reductant particles; it is beneficial to the uniform adhesion of the oxidant and reductant drug particles, improving the drug retention rate and ensuring stable ignition of the prepared ignition paper; 3. The fiber material obtained by the method defined in the present invention has good bonding strength, high bulk density of the paper formed by wet papermaking, and still has good strength in the ignition paper containing oxidant and reductant particles, meeting the requirements of the battery assembly process and the ignition paper strength during battery transportation; and this material has high temperature resistance, low ignition loss at high temperature, and does not participate in the redox reaction of drug particles, that is, the carrier does not participate in the reaction of the drug during the combustion of the agent and does not generate gas; 5. According to actual needs, the present invention adjusts the pH value of the pulp to be close to neutral or weakly alkaline by acid-base before the wet special paper papermaking process, reducing the influence of fibers on the drug reaction process; 6. The inorganic fiber carrier obtained by the process defined in the present invention has the characteristics of good bonding strength, small pore size, strong ability to adsorb chemical agents, good chemical stability, etc., with a thickness of 0.2 ± 0.05 mm, a bulk density ≤ 0.7 g / cm 3 , a longitudinal tensile strength ≥ 0.20 kN / m, an ignition loss ≤ 10%, and the fiber has a qualified degree of non-entanglement and non-loosening in water, meeting the use requirements of the thermal battery ignition paper. Detailed embodiments

[0015] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law. The following further elaborates on the present invention in conjunction with specific embodiments: Example 1: Weigh 50 kg of wollastonite fiber. After primary screening, put it into a beating machine. The beating consistency is 3.0% (that is, the fiber raw material accounts for 3% of the total weight of the fiber and water mixture, the same below). Beat with the knife until the beating degree reaches 70°SR and the wet weight is 5 - 6 g. The fibers are respectively loosened to single fibers with a light knife in the beating machine. Then, this fiber slurry is centrifugally desanded with a conical desander. The slurry consistency during desanding is 1%. The treated fibers are added with water to make the slurry consistency 0.2%. Adjust its pH = 8.0 by adding 30% liquid caustic soda solution in the pulp according to the pH of the pulp. Then, use a wet special paper making machine to make wollastonite fiber paper, and after appropriate surface finishing treatment, the obtained paper has a thickness of 0.21 mm and a bulk density ≤ 0.7 g / cm 3 , the longitudinal tensile strength ≥ 0.20 kN / m, and the ignition loss rate: 7.1%.

[0016] Example 2: Weigh 50 kg of brucite fiber. After primary screening, put it into a beating machine. The beating consistency is 3.5%. Beat with the knife until the beating degree reaches 85°SR and the wet weight is 5 - 8 g. The fibers are respectively loosened to single fibers with a light knife in the beating machine. Then, the fiber slurry is centrifugally desanded with a conical desander. The slurry consistency during desanding is 1%. The treated fibers are added with water to make the slurry consistency 0.2%. Adjust the pH = 7 by adding 31% hydrochloric acid solution in the pulp according to the pH of the pulp. Then, use a wet special paper making equipment to make wollastonite fiber paper, and after appropriate surface finishing treatment, the obtained paper has a thickness of 0.22 mm and a bulk density ≤ 0.7 g / cm 3 , the longitudinal tensile strength ≥ 0.18 kN / m, and the ignition loss rate: 6.2%.

[0017] Example 3: Weigh 45 kg of sepiolite fiber and 5 kg of glass fiber, and put them into a beating machine at an addition ratio of 9:1. The beating consistency is 3%. Beat with the knife until the beating degree reaches 75°SR and the wet weight is 5 - 6 g. The fibers are respectively loosened to single fibers with a light knife in the beating machine. Then, this fiber slurry is centrifugally desanded with a conical desander. The slurry consistency during desanding is 1%. The treated fibers are added with water to make the slurry consistency 0.2%. Adjust its pH = 7.5 by adding 30% liquid caustic soda solution in the pulp according to the pH of the pulp. Then, use a wet special paper making machine to make inorganic fiber paper, and after appropriate surface finishing treatment, the obtained paper has a thickness of 0.20 mm and a bulk density ≤ 0.7 g / cm 3, the longitudinal tensile strength ≥ 0.20 kN / m, the loss on ignition: 9.1%.

[0018] Example 4 Weigh 50 kg of sepiolite fiber, put it into a beater after primary screening, the beating consistency is 3.0%, cut the pulp until the beating degree reaches 55°SR, the wet weight is 5 - 6 g, the fibers are separately loosened to single fibers in the beater, then the fiber pulp is centrifugally desanded with a conical desander, the pulp consistency during desanding is 1%, the treated fibers are diluted with water to a pulp consistency of 0.2%. Adjust the pH of the pulp to 8.0 by adding 30% liquid caustic soda solution according to the pH of the pulp, then use a wet special paper making machine to make sepiolite fiber paper, and after appropriate surface finishing treatment, the obtained paper has a thickness of 0.21 mm, the longitudinal tensile strength < 0.15 kN / m, and the fiber bonding on the paper surface is poor.

[0019] Example 5 Weigh 50 kg of sepiolite fiber, put it into a beater after primary screening, the beating consistency is 3.0%, cut the pulp until the beating degree reaches 95°SR, the wet weight is 5 - 6 g, the fibers are separately loosened to single fibers in the beater, then the fiber pulp is centrifugally desanded with a conical desander, the pulp consistency during desanding is 1%, the treated fibers are diluted with water to a pulp consistency of 0.2%. Adjust the pH of the pulp to 8.0 by adding 30% liquid caustic soda solution according to the pH of the pulp, then use a wet special paper making machine to make sepiolite fiber paper, and after appropriate surface finishing treatment, but there is difficulty in draining water during the production process, the paper thickness is too thin at 0.15 mm, and the longitudinal tensile strength < 0.15 kN / m.

[0020] Comparative Example Weigh 50 kg of asbestos fiber, put it into a beater after primary screening, the beating consistency is 3.0%, cut the pulp until the beating degree reaches 75°SR, the wet weight is 5 - 6 g, the fibers are separately loosened to single fibers in the beater, then the fiber pulp is centrifugally desanded with a conical desander, the pulp consistency during desanding is 1%, the treated fibers are diluted with water to a pulp consistency of 0.2%. Adjust the pH of the pulp to 7 by adding 31% hydrochloric acid solution according to the pH of the pulp, then use a wet special paper making equipment to make asbestos paper, and after appropriate surface finishing treatment, the obtained loosened paper has a thickness of 0.21 mm, the bulk density 0.7 g / cm 3 , the longitudinal tensile strength 0.15 kN / m, the loss on ignition: 10%.

[0021] For the pH regulator in the examples, other alkalis such as caustic soda flakes, potassium hydroxide or lime water can be used to replace the liquid caustic soda, or acids such as oxalic acid, acetic acid, salicylic acid, acetic acid, citric acid, sulfuric acid, nitric acid or phosphoric acid can be used to replace hydrochloric acid, and the same effect can be achieved.

[0022] The content described in this specification is only an enumeration of the implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. A method for preparing an inorganic fiber carrier for ignition paper, which uses inorganic fiber as raw material, and is successively prepared by fiber beating, purification, pH adjustment and wet special paper process, characterized in that The specific steps include: S1: Put the inorganic fiber into a pulping machine, add water to a pulping concentration of 2.0% to 3.5%, cut it into single fibers in the pulping machine, and beat it into a fiber slurry with a beating degree of 60 to 90°SR and a wet weight of 1 to 30 g; S2: Purify the fiber slurry in step S1 by wet desanding and centrifugal desanding using a conical desander; S3: Add water to the slurry in step S2 to a certain slurry concentration as needed, and then add acid or alkali to adjust the pH to 7-9; S4: The slurry in step S3 is made into inorganic fiber loose paper by using wet-process special paper making equipment, namely, inorganic carrier material.

2. The method for preparing an inorganic fiber carrier for ignition paper according to claim 1, characterized in that The inorganic fiber is non-asbestos inorganic fiber, including a mixture of 90wt% to 100wt% of one or more of wollastonite fiber, palygorskite fiber, sepiolite fiber, brucite fiber, ceramic fiber wool, high alumina polycrystalline fiber, and mullite fiber and 0-10wt% of glass fiber.

3. The method for preparing an inorganic fiber carrier for ignition paper according to claim 1, characterized in that The beating process in step S1 is: using pulping equipment for pulping and papermaking to separate and beat the inorganic fibers, and beating them to a wet weight of 2 to 15 g.

4. The method for preparing an inorganic fiber carrier for ignition paper according to claim 1, characterized in that The slurry concentration during sand removal in step S2 is 0.5-3.0%, preferably 0.5-1.5%.

5. The method for preparing an inorganic fiber carrier for ignition paper according to claim 1, characterized in that In step S3, water is added to prepare the slurry until the slurry concentration is 0.1% to 0.8%.

6. The method for preparing an inorganic fiber carrier for ignition paper according to claim 1, characterized in that The alkali for adjusting the pH value in step S3 is alkali such as flake caustic soda, liquid caustic soda, potassium hydroxide or lime water, and the acid is oxalic acid, acetic acid, salicylic acid, acetic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid.

7. The method for preparing an inorganic fiber carrier for ignition paper according to any one of claims 1 to 6, characterized in that The thickness of the obtained inorganic carrier material is 0.2 ± 0.05 mm, and the density is ≤ 0.7 g / cm 3 , longitudinal tensile strength ≥ 0.20 kN / m, and does not have the ability to oxidize or be oxidized, and its burning reduction rate ≤ 10% (600℃, 15min).