Wear-resistant anti-yellowing white carbon black for smart wear watchband and preparation method thereof

Abstract

The application discloses a kind of wear-resistant and yellowing-resistant white carbon black for intelligent wearing watchband and a preparation method thereof.The white carbon black is prepared from low-iron solid water glass by sequentially performing the following steps: dissolving and diluting to obtain dilute liquid water glass, removing impurities from the dilute liquid water glass by using macroporous strong acid cation exchange resin and amino phosphonic acid chelating resin in series, modifying by using cationic surfactant, acidifying by adding concentrated sulfuric acid, modifying by using non-ionic surfactant, aging and post-treatment.The white carbon black prepared by the application has a significantly reduced iron content and improved whiteness, and the ordered modification improves the interfacial compatibility and binding force between the white carbon black and rubber, fully meeting the requirements of high reinforcement, high dispersion, wear resistance and yellow resistance for intelligent wearing watchband.

Description

Technical Field

[0001] This invention relates to the field of silica production technology, specifically to a wear-resistant and anti-yellowing silica for smart wearable watch straps and its preparation method. Background Technology

[0002] Smart wearable devices are electronic devices that integrate sensing, computing, communication and AI technologies and can be worn directly, such as smartwatches, bracelets, glasses, etc. The smart wearable strap is a key component that connects the watch / bracelet to the wrist. The mainstream materials include rubber, leather, metal, nylon braid, ceramic, etc. Among them, rubber straps are favored by consumers because they are lightweight, soft, waterproof and sweatproof, skin-friendly, have good elasticity, and are inexpensive.

[0003] Silica is a core reinforcing component of rubber watch straps. Because raw silicone rubber is extremely soft, it cannot be used without the reinforcement of silica. Rubber watch straps are prone to yellowing and discoloration due to aging. This is because silica contains a relatively high amount of non-ferrous metals such as iron, copper, and manganese. When used in silicone rubber, these metals easily produce various colors, especially yellow. The main reason for the high content of these metals in silica is that the raw materials used in its production, such as water glass, also contain these metals. Therefore, reducing the content of non-ferrous metals in silica is one effective way to improve the yellowing resistance of rubber watch straps and extend their service life.

[0004] Current research focuses on incorporating silica into silicone rubber systems along with antioxidants, iron-removing complexing agents, or by directly adding dark pigments for masking. However, this method of compensating with additives can lead to their failure in subsequent use due to factors such as ultraviolet radiation, high temperatures, and sweat stains, resulting in loss of anti-yellowing properties and poor durability. In summary, effectively removing non-ferrous metals during the production of silica and fundamentally solving the problem of yellowing when silica is used in the production of silicone rubber is of positive significance for improving the quality and market competitiveness of silicone rubber watch straps. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems. This invention proposes a wear-resistant and anti-yellowing silica for smart wearable watch straps and its preparation method.

[0006] The present invention achieves the above objectives through the following technical solutions: As a first aspect of the present invention, a wear-resistant and anti-yellowing white carbon black for smart wearable watch straps is provided. It is prepared by first dissolving and diluting low-iron solid water glass to obtain dilute liquid water glass, and then subjecting the dilute liquid water glass to impurity removal by a series of macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, modification with cationic surfactant, acidification with concentrated sulfuric acid, modification with nonionic surfactant, aging and post-treatment.

[0007] As a further optimization of the present invention, the cationic surfactant is tetradecylmethyldihydroxyethylammonium bromide or hexadecylmethyldihydroxyethylammonium bromide.

[0008] As a further optimization of the present invention, the nonionic surfactant is alkyl glycoside APG0810 or alkyl glycoside APG1214.

[0009] As a further optimization of the present invention, the modulus of the low-iron solid water glass is 3.1-3.7, the iron content in the low-iron solid water glass is 100-150 ppm, and the mass ratio of the dilute liquid water glass to concentrated sulfuric acid is 6-7:1.

[0010] As a further optimization of the present invention, the amount of the cationic surfactant added accounts for 1.2-1.8 wt% of the mass of the dilute liquid water glass; The amount of the nonionic surfactant added is 2.0-3.0 wt% of the mass of the dilute liquid water glass.

[0011] As a second aspect of the present invention, a method for preparing wear-resistant and anti-yellowing silica for smart wearable watch straps as described in any of the above claims is provided, comprising the following steps: (1) Put low-iron solid water glass into a drum distillation ball, first add deionized water in three stages of heating and pressurization in the drum distillation ball, and then pass water vapor to maintain pressure so that the low-iron solid water glass is completely dissolved. After sedimentation and slag removal, concentrated liquid water glass is obtained. (2) Add deionized water to concentrated liquid water glass to prepare dilute liquid water glass with a concentration of 25-30wt%; (3) Dilute liquid water glass is first introduced into the exchange column of macroporous strong acid cation exchange resin for ion exchange. The dilute liquid water glass flowing out of the macroporous strong acid cation exchange resin is then introduced into aminophosphonic acid chelating resin. The liquid is collected at the outlet of the aminophosphonic acid chelating resin. (4) Dilute liquid water glass, which has been purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to the fluoroplastic-lined reactor. Water vapor is introduced and the water vapor pressure is maintained at 0.4-0.6 MPa. The temperature is raised to 80-90℃ and kept at that temperature. Under stirring conditions, cationic surfactants are added at a uniform speed. Then concentrated sulfuric acid is added for acidification and the pH value is adjusted to 3-4. Under stirring conditions, nonionic surfactants are added at a uniform speed and the reactor is aged. (5) The material obtained in step (4) is filtered, washed and pulped to obtain slurry. The slurry is spray-dried, crushed and sieved to obtain wear-resistant and anti-yellowing white carbon for smart wearable watch straps.

[0012] As a further optimization of the present invention, in step (1), the ratio of the low-iron solid water glass to deionized water is 1:2.4-3.2, and the deionized water is added in a three-stage heating and pressurization manner: the three-stage addition ratio of deionized water is 4:2-3:1-2, the corresponding temperatures of the three stages are 80-90℃, 95-105℃, and 110-115℃, and the heating rate is 2-4℃ / min; the corresponding pressure conditions of the three stages are 0.1-0.15MPa, 0.2-0.3MPa, and 0.5-0.6MPa, and each stage is kept at a temperature for 10-15min after heating.

[0013] As a further optimization of the present invention, in step (3), the pH value is adjusted to 10.5-13.0 before the dilute liquid water glass is introduced into the macroporous strong acid cation exchange resin. The flow rate of the dilute liquid water glass in the macroporous strong acid cation exchange resin is 2-4 BV / h, and the flow rate in the aminophosphonic acid chelating resin is 1-2 BV / h.

[0014] As a further optimization of the present invention, in step (4), the addition time of both the cationic surfactant and the nonionic surfactant is 10-20 min.

[0015] As a further optimization of the present invention, in step (4), the aging temperature is 80-90℃ and the aging time is 30-60min.

[0016] The beneficial effects of this invention are as follows: (1) In the process of dissolving low-iron solid water glass, the present invention adopts a three-stage heating and pressurization addition method for deionized water. Compared with the three-stage heating and constant pressure addition, the three-stage constant temperature and pressurization addition, the three-stage constant temperature and constant pressure addition and the one-stage constant temperature and constant pressure addition method, the dissolution rate of low-iron solid water glass can reach more than 99%, and the residue is less than 0.5%. The raw materials are fully dissolved and the loss is controllable, which can be adapted to industrial continuous large-scale production.

[0017] (2) The present invention adopts a dual resin series impurity removal process of macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, which can effectively reduce the iron content in silica and increase the whiteness of silica.

[0018] (3) The present invention adopts a stepwise modification method of first adding cationic surfactant, then acidifying, and then adding nonionic surfactant alkyl glycoside. This method can achieve in-situ uniform organic coating of silica particles, inhibit agglomeration, increase specific surface area, and at the same time strengthen the interfacial bonding and dispersibility with rubber, thereby effectively improving the product's tanδ (0℃), tensile strength and activation degree.

[0019] In summary, the precipitated silica prepared by this invention has significantly reduced iron content and improved whiteness. At the same time, the orderly modification improves the interfacial compatibility and bonding force between precipitated silica and rubber, fully meeting the requirements of high reinforcement, high dispersion, wear resistance and anti-yellowing for smart wearable watch straps. Detailed Implementation

[0020] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above content.

[0021] The present invention achieves the following technical solution through at least one embodiment: This embodiment provides a method for preparing wear-resistant and yellowing-resistant silica for smart wearable watch straps, including the following steps: (1) Put low-iron solid water glass into a drum distillation ball, add deionized water into the drum distillation ball first, and pass water vapor through to maintain pressure so that the low-iron solid water glass is completely dissolved. After precipitation and removal of residue, concentrated liquid water glass is obtained. The ratio of low-iron solid water glass to deionized water is 1:2.4-3.2. The deionized water is added in three stages with increasing temperature and pressure: the ratio of deionized water added in three stages is 4:2-3:1-2, the corresponding temperatures for the three stages are 80-90℃, 95-105℃, and 110-115℃, and the heating rate is 2-4℃ / min; the corresponding pressure conditions for the three stages are 0.1-0.15MPa, 0.2-0.3MPa, and 0.5-0.6MPa, and each stage is held at that temperature for 10-15 minutes after heating. (2) Add deionized water to concentrated liquid water glass to prepare dilute liquid water glass with a concentration of 25-30wt%; (3) Adjust the pH of the dilute liquid water glass to 10.5-13.0, and first pass it into the exchange column of the macroporous strong acid cation exchange resin for ion exchange. The flow rate is controlled at 2-4 BV / h. Then, pass the dilute liquid water glass flowing out of the macroporous strong acid cation exchange resin into the aminophosphonic acid chelating resin. The flow rate is controlled at 1-2 BV / h. Collect the liquid at the outlet of the aminophosphonic acid chelating resin. (4) Dilute liquid water glass, which has been purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to a fluoroplastic-lined reactor. Steam is introduced and the steam pressure is maintained at 0.4-0.6 MPa. The temperature is raised to 80-90℃ and kept at that temperature. Under stirring conditions, cationic surfactant tetradecylmethyldihydroxyethylammonium bromide or hexadecylmethyldihydroxyethylammonium bromide is added at a uniform rate for 10-20 min. Then, concentrated sulfuric acid with a mass concentration of 98% is added and acidified for 20-30 min. The pH value is adjusted to 3-4. Under stirring conditions, alkyl glycosides (alkyl glycoside APG0810, alkyl glycoside APG1214) are added at a uniform rate for 10-20 min. The reactor is aged at 80-90℃ for 30-60 min. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid is 6-7:1; the amount of cationic surfactant added is 1.2-1.8 wt% of the mass of dilute liquid water glass; and the amount of alkyl glycoside added is 2.0-3.0 wt% of the mass of dilute liquid water glass. (5) The material obtained in step (4) is filtered, washed and pulped to obtain a slurry. The slurry is spray-dried, crushed and sieved to obtain a white powder product, which is white carbon black. The following embodiments do not modify step (5). The operation process of step (5) in the following embodiments is uniformly as follows: the mother liquor is separated by plate and frame pressure separation, and then washed countercurrently until the conductivity of the filtrate is less than 50 μS / cm and the SO4 content is less than 50 μS / cm. 2- <0.5%, pH about 5-7. Add deionized water to the filter cake (solid content of 25%), slurry until uniform (solidified 15%), and finally spray dry at 300℃ at the inlet and 100℃ at the outlet.

[0022] The modulus of low-iron solid water glass is 3.1-3.7; The iron content in low-iron solid water glass is 100-150 ppm; The model of the macroporous strong acid cation exchange resin is D001 type macroporous strong acid cation exchange resin. The aminophosphonic acid chelating resin is designated as D418 macroporous aminophosphonic acid chelating resin. In alkyl glycoside APG0810, 0810 refers to a carbon chain length of 8-10, and the same applies to alkyl glycoside APG1214.

[0023] In the following examples, all reagents are commercially available chemicals unless otherwise specified. Unless otherwise stated, all experimental methods are performed according to conventional methods.

[0024] Example 1

[0025] This embodiment provides a method for preparing wear-resistant and anti-yellowing silica for smart wearable watch straps, including the following steps: (1) Put low-iron solid water glass into a drum distillation ball, add deionized water into the drum distillation ball first, and pass water vapor through to maintain pressure so that the low-iron solid water glass is completely dissolved. After precipitation and removal of residue, concentrated liquid water glass is obtained. The ratio of low-iron solid water glass to deionized water is 1:2.4. The deionized water is added in three stages with increasing temperature and pressure: the ratio of deionized water added in the three stages is 4:3:2, the corresponding temperatures of the three stages are 90℃, 105℃, and 115℃, and the heating rate is 3℃ / min; the corresponding pressure conditions of the three stages are 0.1MPa, 0.3MPa, and 0.5MPa, and each stage is held at that temperature for 10min after heating. (2) Add deionized water to concentrated liquid water glass to prepare dilute liquid water glass with a concentration of 30wt%; (3) Dual resin series impurity removal: Adjust the pH of the dilute liquid water glass to 13.5, and first pass it into the exchange column of the macroporous strong acid cation exchange resin for ion exchange. The flow rate is controlled at 4 BV / h. Then, pass the dilute liquid water glass flowing out of the macroporous strong acid cation exchange resin into the aminophosphonic acid chelating resin. The flow rate is controlled at 2 BV / h. Collect the liquid at the outlet of the aminophosphonic acid chelating resin. (4) Dilute liquid water glass, which has been purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to a fluoroplastic-lined reactor. Water vapor is introduced and the water vapor pressure is maintained at 0.6 MPa. The temperature is raised to 80°C and kept at that temperature. Under stirring conditions, the cationic surfactant cetylmethyldihydroxyethylammonium bromide is added at a uniform rate for 20 min. Then, concentrated sulfuric acid with a mass concentration of 98% is added and acidified for 20 min. The pH value is adjusted to 3-4. Under stirring conditions, alkyl glycoside APG1214 is added at a uniform rate for 20 min. Then, the reactor is aged at 85°C for 30 min. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid was 6:1; the amount of cationic surfactant added accounted for 1.2 wt% of the mass of dilute liquid water glass; and the amount of alkyl glycoside added accounted for 2.0 wt% of the mass of dilute liquid water glass. (5) The material obtained in step (4) is filtered, washed and pulped to obtain slurry. The slurry is spray-dried, crushed and sieved to obtain a white powder product, which is white carbon black.

[0026] Example 2

[0027] This embodiment provides a method for preparing wear-resistant and yellowing-resistant silica for smart wearable watch straps, including the following steps: (1) Put low-iron solid water glass into a drum distillation ball, add deionized water into the drum distillation ball first, and pass water vapor through to maintain pressure so that the low-iron solid water glass is completely dissolved. After precipitation and removal of residue, concentrated liquid water glass is obtained. The ratio of low-iron solid water glass to deionized water is 1:3.2. The deionized water is added in three stages with increasing temperature and pressure: the ratio of deionized water added in the three stages is 4:2:1, the corresponding temperatures are 80℃, 95℃, and 110℃, the heating rate is 4℃ / min, the corresponding pressure conditions are 0.15MPa, 0.3MPa, and 0.6MPa, and each stage is held at that temperature for 15min after heating. (2) Add deionized water to concentrated liquid water glass to prepare dilute liquid water glass with a concentration of 25wt%; (3) Adjust the pH of the dilute liquid water glass to 10.5, and pass it into the exchange column of the macroporous strong acid cation exchange resin for ion exchange. The flow rate is controlled at 2 BV / h. Then, pass the dilute liquid water glass flowing out of the macroporous strong acid cation exchange resin into the aminophosphonic acid chelating resin. The flow rate is controlled at 1 BV / h. Collect the liquid at the outlet of the aminophosphonic acid chelating resin. (4) Dilute liquid water glass, which has been purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to a fluoroplastic-lined reactor. Water vapor is introduced and the water vapor pressure is maintained at 0.4 MPa. The temperature is raised to 90°C and kept at that temperature. Under stirring conditions, the cationic surfactant tetradecylmethyldihydroxyethylammonium bromide is added at a uniform rate for 10 min. Then, concentrated sulfuric acid with a mass concentration of 98% is added and acidified for 30 min. The pH value is adjusted to 3-4. Under stirring conditions, alkyl glycoside APG1214 is added at a uniform rate for 10 min. Then, the reactor is aged at 90°C for 30 min. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid was 7:1; the amount of cationic surfactant added accounted for 1.4 wt% of the mass of dilute liquid water glass; and the amount of alkyl glycoside added accounted for 2.5 wt% of the mass of dilute liquid water glass. (5) The material obtained in step (4) is filtered, washed and pulped to obtain a slurry. The slurry is spray-dried, crushed and sieved to obtain a white powder product, which is white carbon black.

[0028] Example 3

[0029] This embodiment provides a method for preparing wear-resistant and yellowing-resistant silica for smart wearable watch straps, including the following steps: (1) Put low-iron solid water glass into a drum distillation ball, add deionized water into the drum distillation ball first, and pass water vapor through to maintain pressure so that the low-iron solid water glass is completely dissolved. After precipitation and removal of residue, concentrated liquid water glass is obtained. The ratio of low-iron solid water glass to deionized water is 1:3. The deionized water is added in three stages with increasing temperature and pressure: the ratio of deionized water added in the three stages is 4:3:1, the corresponding temperatures are 85℃, 100℃, and 115℃, the heating rate is 2℃ / min, the corresponding pressure conditions are 0.15MPa, 0.25MPa, and 0.55MPa, and each stage is held at that temperature for 10min after heating. (2) Add deionized water to concentrated liquid water glass to prepare dilute liquid water glass with a concentration of 30wt%; (3) Adjust the pH of the dilute liquid water glass to 11.5, and pass it into the exchange column of the macroporous strong acid cation exchange resin for ion exchange. The flow rate is controlled at 3 BV / h. Then, pass the dilute liquid water glass flowing out of the macroporous strong acid cation exchange resin into the aminophosphonic acid chelating resin. The flow rate is controlled at 1 BV / h. Collect the liquid at the outlet of the aminophosphonic acid chelating resin. (4) Dilute liquid water glass, which has been purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to a fluoroplastic-lined reactor. Water vapor is introduced and the water vapor pressure is maintained at 0.5 MPa. The temperature is raised to 85°C and kept at that temperature. Under stirring conditions, cationic surfactant tetradecylmethyldihydroxyethyl ammonium bromide is added at a uniform rate for 15 min. Then, concentrated sulfuric acid with a mass concentration of 98% is added and acidified for 25 min. The pH value is adjusted to 3-4. Under stirring conditions, APG0810 is added at a uniform rate for 15 min. Then, the reactor is aged at 80°C for 60 min. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid was 7:1; the amount of cationic surfactant added accounted for 1.8 wt% of the mass of dilute liquid water glass; and the amount of alkyl glycoside added accounted for 3.0 wt% of the mass of dilute liquid water glass. (5) The material obtained in step (4) is filtered, washed and pulped to obtain a slurry. The slurry is spray-dried, crushed and sieved to obtain a white powder product, which is white carbon black.

[0030] Verification test 1. In the preparation of concentrated liquid water glass in Examples 1-3 of this application, deionized water is added in a three-stage heating and pressurization manner. In order to investigate the effect of different deionized water addition methods on the preparation efficiency of concentrated liquid water glass, the following deionized water addition methods are set up, and the optimal addition method of deionized water is determined by comparing the dissolution rate. Let M0 be the initial mass of low-iron solid water glass, and M1 be the mass of the residue after precipitation and slag removal. The dissolution rate is calculated using the following formula: {(M0-M1) / M0}×100% Comparison with dosing method A: Three-stage heating and constant pressure dosing: The ratio of deionized water added in three stages is 4:2:1, the corresponding temperatures of the three stages are 80℃, 95℃, and 110℃, the heating rate is 4℃ / min; the corresponding pressure conditions of the three stages are all 0.6MPa, and the temperature is maintained for 10min after each stage heating. Comparison with addition method B: Three-stage constant temperature and pressure addition: The ratio of deionized water added in three stages is 4:2:1, the temperature is increased to 110℃ at 4℃ / min, the temperature of each stage is 110℃, the pressure conditions of each stage are 0.15MPa, 0.3MPa and 0.6MPa, and the temperature is maintained for 10min under each pressure condition; Comparison with addition method C: constant temperature and pressure three-stage addition: the ratio of deionized water added in three stages is 4:2:1, the temperature is increased to 110℃ at 4℃ / min, the temperature of each stage is 110℃, the pressure of each stage is 0.6MPa, and the next addition is carried out after each stage is 10min apart. Comparison with addition method D: One-stage constant temperature and pressure addition: Low iron solid water glass and deionized water are added together into the drum steamer at a ratio of 1:3.2, the temperature is raised to 110℃ at 4℃ / min, and water steam is introduced until the pressure value is 0.6MPa, and the pressure and temperature are maintained for 30min.

[0031] The results are summarized in Table 1.

[0032] Table 1. Effects of different deionized water addition methods on the dissolution rate of low-iron solid water glass. As can be seen from the table, in Examples 1-3, the dissolution rate of low-iron solid water glass was over 99% with a residue of less than 0.5% when deionized water was added in a three-stage heating and pressurization manner, and the raw material was fully dissolved with controllable loss. In contrast, the dissolution rate of low-iron solid water glass was reduced to varying degrees when adding water in three stages of heating and pressurization, three stages of constant temperature and pressurization, three stages of constant temperature and pressurization, and one stage of constant temperature and pressurization, which is not suitable for continuous large-scale industrial production.

[0033] To verify the effect of different impurity removal methods on the iron content in the prepared silica, based on the preparation method provided in Example 1, only the step (3) of dual-resin tandem impurity removal was adjusted. The specific comparison after adjustment is as follows: Comparative Example 1 The only difference from Example 1 is that the aminophosphonic acid chelating resin in Example 1 is replaced with a macroporous strong acid cation exchange resin. Comparative Example 2 The only difference from Example 1 is that the macroporous strong acid cation exchange resin of Example 1 is replaced with an aminophosphonic acid chelating resin.

[0034] Comparative Example 3 The only difference from Example 1 is that the order of use of the macroporous strong acid cation exchange resin and the aminophosphonic acid chelating resin in Example 1 is reversed, that is, the aminophosphonic acid chelating resin is used first, followed by the macroporous strong acid cation exchange resin for impurity removal.

[0035] Comparative Example 4 The only difference from Example 1 is that the dual resin series impurity removal process in step (3) is not performed.

[0036] The iron content in the silica prepared in Example 1 and the silica prepared in Comparative Examples 1-4 was determined, and the whiteness of the silica was tested using a ZBD type whiteness meter.

[0037] The iron content in silica was determined in accordance with GB / T36764-2018 "Determination of Heavy Metal Content in Rubber Compounding Agents by Inductively Coupled Plasma Atomic Emission Spectrometry".

[0038] Each group is set up with 3 parallel results, and the results are calculated as the average.

[0039] The results are summarized in Table 2.

[0040] Table 2 Statistical Table of Results As can be seen from Table 2, the dual-resin series purification process of macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin adopted in Example 1 can effectively reduce the iron content in silica, thereby increasing the whiteness of silica. In comparison, using macroporous strong acid cation exchange resin alone or using aminophosphonic acid chelating resin alone is not as effective in reducing the iron content in silica as using both in series. To verify the effect of different modification methods on the iron content in the prepared silica, only step (4) was adjusted based on the preparation method provided in Example 1. The specific comparison after adjustment is as follows: Comparative Example 5 The only difference between this comparative example and Example 1 is that: Dilute liquid water glass, purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, was slowly added to a fluoroplastic-lined reactor. Steam was introduced and maintained at a pressure of 0.6 MPa. The temperature was raised to 80°C and held. Under stirring conditions, the cationic surfactant cetylmethyldihydroxyethylammonium bromide was added at a uniform rate over a period of 20 minutes. Then, concentrated sulfuric acid with a mass concentration of 98% was added, and the mixture was acidified for 20 minutes. The pH was adjusted to 3-4, and the mixture was then aged at 85°C for 30 minutes.

[0041] The mass ratio of dilute liquid water glass to 98% concentrated sulfuric acid is 7:1, and the amount of cationic surfactant cetylmethyldihydroxyethylammonium bromide added accounts for 1.2 wt% of the mass of dilute liquid water glass.

[0042] Comparative Example 6 The only difference between this comparative example and Example 1 is that: Dilute liquid water glass, purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, was slowly added to a fluoroplastic-lined reactor. Steam was introduced and the steam pressure was maintained at 0.6 MPa. The temperature was raised to 80°C and kept at that temperature. Concentrated sulfuric acid with a mass concentration of 98% was added and acidified for 20 minutes. The pH was adjusted to 3-4. Under stirring conditions, alkyl glycoside APG1214 was added at a uniform rate over a period of 20 minutes. The reactor was then aged at 85°C for 30 minutes. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid is 6:1, and the amount of alkyl glycoside APG1214 added accounts for 2.0 wt% of the mass of dilute liquid water glass.

[0043] Comparative Example 7 The only difference between this comparative example and Example 1 is that: Dilute liquid water glass, purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, was slowly added to a fluoroplastic-lined reactor. Steam was introduced and the steam pressure was maintained at 0.6 MPa. The temperature was raised to 80°C and held. Then, concentrated sulfuric acid with a mass concentration of 98% was added and acidified for 20 minutes. The pH was adjusted to 3-4. Under stirring conditions, the cationic surfactants hexadecylmethyldihydroxyethylammonium bromide and APG1214 were added at a uniform rate over a period of 20 minutes. The reactor was then aged at 85°C for 30 minutes. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid is 6:1. The amount of cationic surfactant added accounts for 1.2 wt% of the mass of dilute liquid water glass, and the amount of alkyl glycoside added accounts for 2.0 wt% of the mass of dilute liquid water glass.

[0044] Comparative Example 8 The only difference between this comparative example and Example 1 is that: Dilute liquid water glass, purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, was slowly added to a fluoroplastic-lined reactor. Steam was introduced and the steam pressure was maintained at 0.6 MPa. The temperature was raised to 80°C and held. Under stirring, alkyl glycoside APG1214 was added at a uniform rate over a period of 20 min. Then, concentrated sulfuric acid with a mass concentration of 98% was added and acidified for 20 min. The pH was adjusted to 3-4. Under stirring, the cationic surfactant hexadecylmethyldihydroxyethylammonium bromide was added at a uniform rate over a period of 20 min. The reactor was then aged at 85°C for 30 min. The ratio of dilute liquid water glass to 98% concentrated sulfuric acid is 6:1. The amount of cationic surfactant added accounts for 1.2 wt% of the mass of dilute liquid water glass, and the amount of alkyl glycoside added accounts for 2.0 wt% of the mass of dilute liquid water glass.

[0045] Comparative Example 9 The only difference between this comparative example and Example 1 is that: Dilute liquid water glass, purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to a fluoroplastic-lined reactor. Steam is introduced and the steam pressure is maintained at 0.6 MPa. The temperature is raised to 80°C and held. Concentrated sulfuric acid with a mass concentration of 98% is added, and the reactor is acidified for 20 minutes. The pH value is adjusted to 3-4, and then the reactor is aged at 85°C for 30 minutes.

[0046] The mass ratio of dilute liquid water glass to 98% concentrated sulfuric acid is 6:1.

[0047] The following tests were performed on the silica prepared in Examples 1-3 and Comparative Examples 5-9: Specific surface area determination: The specific surface area (BET) of silica was determined according to GB / T10722-2014 "Determination of total surface area and external surface area of ​​carbon black by nitrogen adsorption method".

[0048] The silica prepared in Examples 1-3 and Comparative Examples 5-9 were respectively prepared into rubber, and their tanδ (0℃) and tensile strength were measured. Specifically, vulcanizates were prepared according to HG / T2404-2020, and the tensile strength of the vulcanizates (MPa) was tested according to GB / T528-2009. The test conditions for the loss factor tanδ (0℃) of the vulcanizate were a frequency of 50Hz and a dynamic strain of 1%, and the test equipment was a dynamic thermomechanical analyzer.

[0049] The activation degree was determined as follows: 50 mL of distilled water was placed in a 100 mL beaker, 1.0 g of silica was added, and the mixture was stirred for 30 min and allowed to stand for 24 h. The silica that sank to the bottom was separated, dried, and weighed. The activation degree was calculated as follows: activation degree = {(total mass of silica - mass of silica that sank to the bottom) / total mass of silica} × 100%.

[0050] The results are summarized in Table 3.

[0051] Table 3 Statistical Table of Results As shown in Table 3, the stepwise modification of Examples 1-3, which involves first adding a cationic surfactant, then acidifying, and finally adding a nonionic surfactant alkyl glycoside, can achieve in-situ uniform organic coating of silica particles, inhibit agglomeration, increase specific surface area, and strengthen the interfacial bonding and dispersibility with rubber. This results in a significant improvement in the product's tanδ (0℃), tensile strength, and activation degree compared to the comparative example. Tanδ (0℃) reflects the rubber's wet slip / abrasion-related loss properties. The orderly modification makes the silica more uniformly dispersed in the rubber, strengthens the interfacial bonding, and allows for more complete energy dissipation under external forces.

[0052] Based on the above experiments, it can be seen that the iron content of the silica prepared by the present invention is significantly reduced and the whiteness is improved. At the same time, the orderly modification improves the interfacial compatibility and bonding force between silica and rubber, which fully meets the requirements of high reinforcement, high dispersion, wear resistance and anti-yellowing of smart wearable watch straps.

[0053] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A type of wear-resistant and anti-yellowing silica for smart wearable watch straps, characterized in that, The process involves first dissolving and diluting low-iron solid water glass to obtain dilute liquid water glass, then subjecting the dilute liquid water glass to a series of impurity removal processes using macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, followed by modification with cationic surfactants, acidification with concentrated sulfuric acid, modification with nonionic surfactants, aging, and post-treatment.

2. The wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 1, characterized in that, The cationic surfactant is tetradecylmethyldihydroxyethylammonium bromide or hexadecylmethyldihydroxyethylammonium bromide.

3. The wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 1, characterized in that, The nonionic surfactant is alkyl glycoside APG0810 or alkyl glycoside APG1214.

4. The wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 1, characterized in that, The modulus of the low-iron solid water glass is 3.1-3.7, the iron content in the low-iron solid water glass is 100-150 ppm, and the mass ratio of the dilute liquid water glass to concentrated sulfuric acid is 6-7:

1.

5. The wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 1, characterized in that, The cationic surfactant is added at a rate of 1.2-1.8 wt% of the mass of the dilute liquid water glass. The amount of the nonionic surfactant added is 2.0-3.0 wt% of the mass of the dilute liquid water glass.

6. A method for preparing wear-resistant and anti-yellowing silica for smart wearable watch straps as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Put low-iron solid water glass into a drum distillation ball, first add deionized water in three stages of heating and pressurization in the drum distillation ball, and then pass water vapor to maintain pressure so that the low-iron solid water glass is completely dissolved. After sedimentation and slag removal, concentrated liquid water glass is obtained. (2) Add deionized water to concentrated liquid water glass to prepare dilute liquid water glass with a concentration of 25-30wt%; (3) Dilute liquid water glass is first introduced into the exchange column of macroporous strong acid cation exchange resin for ion exchange. The dilute liquid water glass flowing out of the macroporous strong acid cation exchange resin is then introduced into aminophosphonic acid chelating resin. The liquid is collected at the outlet of the aminophosphonic acid chelating resin. (4) Dilute liquid water glass, which has been purified by macroporous strong acid cation exchange resin and aminophosphonic acid chelating resin, is slowly added to the fluoroplastic-lined reactor. Water vapor is introduced and the water vapor pressure is maintained at 0.4-0.6 MPa. The temperature is raised to 80-90℃ and kept at that temperature. Under stirring conditions, cationic surfactants are added at a uniform speed. Then concentrated sulfuric acid is added for acidification and the pH value is adjusted to 3-4. Under stirring conditions, nonionic surfactants are added at a uniform speed and the reactor is aged. (5) The material obtained in step (4) is filtered, washed and pulped to obtain slurry. The slurry is spray-dried, crushed and sieved to obtain wear-resistant and anti-yellowing white carbon for smart wearable watch straps.

7. The method for preparing wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 6, characterized in that, In step (1), the ratio of low-iron solid water glass to deionized water is 1:2.4-3.2, and the deionized water is added in three stages with increasing temperature and pressure: the ratio of deionized water added in the three stages is 4:2-3:1-2, the corresponding temperatures of the three stages are 80-90℃, 95-105℃, and 110-115℃, and the heating rate is 2-4℃ / min; the corresponding pressure conditions of the three stages are 0.1-0.15MPa, 0.2-0.3MPa, and 0.5-0.6MPa, and each stage is kept at the temperature for 10-15min after heating.

8. The method for preparing wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 6, characterized in that, In step (3), the pH value is adjusted to 10.5-13.0 before the dilute liquid water glass is introduced into the macroporous strong acid cation exchange resin. The flow rate of the dilute liquid water glass in the macroporous strong acid cation exchange resin is 2-4 BV / h, and the flow rate in the aminophosphonic acid chelating resin is 1-2 BV / h.

9. The method for preparing wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 6, characterized in that, In step (4), the cationic surfactant and the nonionic surfactant are added at a time of 10-20 min.

10. The wear-resistant and anti-yellowing silica for smart wearable watch straps according to claim 6, characterized in that, In step (4), the aging temperature is 80-90℃ and the aging time is 30-60min.

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