Composition, propylene oxide modified cashew phenol, its preparation method and its application in epoxy grout

Abstract

This invention provides a composition, propylene oxide-modified cashew nut shell powder, its preparation method, and its application in epoxy grout. It belongs to the field of epoxy grout technology. The composition forming the propylene oxide-modified cashew nut shell powder comprises, by weight parts: 1000 parts cashew nut shell powder, 720-780 parts propylene oxide, 8-12 parts quaternary ammonium salt phase transfer catalyst, 1.2-1.8 parts antioxidant, and 2.0-3.0 parts acid neutralizer.

Description

Technical Field

[0001] This invention belongs to the field of epoxy grout technology, and particularly relates to a composition, propylene oxide-modified cashew phenol, its preparation method, and its application in epoxy grout. Background Technology

[0002] Epoxy grout, as a core material for filling gaps in building tiles, has stringent requirements regarding low viscosity, smooth application, high transparency after curing, resistance to yellowing, and compatibility. High-end white / light-colored grout, in particular, has even stricter requirements for raw material color and resistance to yellowing. Currently, commonly used epoxy grout thinners have many drawbacks, such as poor environmental friendliness, easy precipitation after curing, and poor yellowing resistance. Furthermore, they are prone to further oxidation and discoloration during storage, making them unsuitable for long-term use in home decoration. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a composition, propylene oxide-modified cashew phenol, its preparation method, and its application in epoxy grout, aiming to at least partially solve the above-mentioned technical problems. The technical solution provided by this invention is as follows.

[0004] As a first aspect of the invention, a composition for forming propylene oxide-modified cashew nut shells is provided, comprising, by weight parts: 1000 parts cashew nut shells, 720-780 parts propylene oxide, 8-12 parts quaternary ammonium salt phase transfer catalyst, 1.2-1.8 parts antioxidant, and 2.0-3.0 parts acid neutralizer.

[0005] As a second aspect of the present invention, a method for preparing propylene oxide-modified cashew nut shells using the above composition is provided, comprising: adding cashew nut shells, a quaternary ammonium salt phase transfer catalyst, and an antioxidant into a reactor; introducing an inert gas to replace the air in the reactor and maintaining a slightly positive pressure; starting stirring and simultaneously raising the temperature to a first temperature to mix and activate the quaternary ammonium salt phase transfer catalyst and cashew nut shells in the reactor; controlling the temperature in the reactor to rise to a second temperature, and then adding propylene oxide dropwise to carry out an addition reaction; after aging and vacuum devolatilization treatment, introducing an inert gas to restore atmospheric pressure and simultaneously lowering the temperature to a third temperature, and adding an acidic neutralizing agent for neutralization to obtain propylene oxide-modified cashew nut shells.

[0006] As a third aspect of the present invention, propylene oxide-modified cashew nut shell powder is provided, which is prepared by the above method, wherein the addition molar ratio of propylene oxide to cashew nut shell powder is 3-4:1, and the propylene oxide-modified cashew nut shell powder is a light yellow transparent liquid.

[0007] As a fourth aspect of the present invention, an epoxy grout sealant is provided, comprising, by weight parts: a first component and a second component, wherein the first component comprises 100 parts epoxy resin, 5-20 parts of propylene oxide-modified cashew nut shell powder as described above, 6-10 parts fumed silica, and 0.1-0.6 parts silicone defoamer; and the second component comprises 100 parts amine curing agent, 5-20 parts of propylene oxide-modified cashew nut shell powder as described above, 6-10 parts fumed silica, 5-10 parts titanium dioxide, and 0.1-0.5 parts silicone defoamer.

[0008] Based on the above technical solutions, the composition, propylene oxide-modified cashew phenol, its preparation method, and its application in epoxy grout provided by the present invention have at least one of the following beneficial effects:

[0009] (1) In this invention, a quaternary ammonium salt phase transfer catalyst is used instead of a traditional strong base catalyst (such as KOH) to activate cashew phenol. The quaternary ammonium salt phase transfer catalyst can form ion pairs with the phenolic hydroxyl groups in cashew phenol, enhance the nucleophilic activity of the phenolic hydroxyl groups, generate stable phenolic anions, and provide reactive sites for the ring-opening addition of propylene oxide. This activation process is mild and has no strong base oxidation effect, effectively avoiding the problem of double bond oxidation in cashew phenol caused by strong base catalyst, thereby obtaining light-colored propylene oxide modified cashew phenol products.

[0010] (2) In the process of preparing propylene oxide modified cashew phenol in this invention, the addition reaction of cashew phenol and propylene oxide is protected by a micro-positive pressure inert gas protection process throughout the process. At the same time, the temperature of the addition reaction is controlled, which can effectively inhibit the oxidation and discoloration of cashew phenol, reduce the occurrence of side reactions, and ensure that the product has low viscosity characteristics, which is convenient for subsequent processing and use of epoxy grout. Detailed Implementation

[0011] Currently, epoxy grout often uses organic solvents such as benzyl alcohol and butyl glycidyl ether as diluents. However, these diluents generally have problems such as easy volatility, poor environmental performance, and easy precipitation after curing, which leads to whitening and poor yellowing resistance of the epoxy grout layer.

[0012] Cashew nut shell phenol, due to its natural origin and the presence of active phenolic hydroxyl groups and long-chain alkenyl groups, is an ideal toughening and viscosity-reducing raw material for epoxy systems. However, the preparation technology of its modified products has significant shortcomings. Currently, strong alkali catalysis such as potassium hydroxide (KOH) is commonly used to prepare propylene oxide-modified cashew nut shell phenol. However, during the reaction, the unsaturated double bonds in the side chains of cashew nut shell phenol are easily oxidized, resulting in discoloration of the product and a deep color (Gardner value 6-8), making it unsuitable for light-colored grout sealants. Moreover, strong alkali catalysis easily produces side reactions, leading to high product viscosity, poor application smoothness, and further oxidation and discoloration during storage, making its yellowing resistance unsuitable for long-term use in home decoration.

[0013] Furthermore, existing modified cashew nut shell grout preparation processes often employ high-temperature reaction conditions (generally above 120℃), which exacerbates the oxidation and discoloration of the raw materials. Additionally, the catalyst and product have poor compatibility, leading to complex subsequent processing and the potential for residual impurities that affect the final performance of the grout. Therefore, this invention proposes using a quaternary ammonium salt phase transfer catalyst instead of the traditional strong alkali catalyst, while simultaneously controlling the preparation process of propylene oxide-modified cashew nut shell grout. This effectively solves the core technical problems of deep color, high viscosity, and poor yellowing resistance in existing epoxy grout using cashew nut shell nut modified diluents. It also considers the compatibility of the product with other components in the epoxy grout, the smoothness of application, and environmental friendliness, making it suitable for the production and application of high-end white / light-colored grout.

[0014] Specifically, as a first aspect of the present invention, a composition for forming propylene oxide-modified cashew nut shells is provided, comprising, by weight parts: 1000 parts cashew nut shells, 720-780 parts propylene oxide, 8-12 parts quaternary ammonium salt phase transfer catalyst, 1.2-1.8 parts antioxidant, and 2.0-3.0 parts acid neutralizer.

[0015] In this invention, a quaternary ammonium salt phase transfer catalyst is used instead of a traditional strong base catalyst (such as KOH) to activate cashew nut shell phenol. The quaternary ammonium salt phase transfer catalyst can form ion pairs with the phenolic hydroxyl groups in cashew nut shell phenol, enhancing the nucleophilic activity of the hydroxyl groups and generating stable phenoxy anions, providing reactive sites for the ring-opening addition of propylene oxide. The activation process of cashew nut shell phenol by the quaternary ammonium salt phase transfer catalyst is mild, without the oxidation effect of strong base catalysts, effectively avoiding the problem of double bond oxidation in cashew nut shell phenol caused by strong bases, thus obtaining a light-colored propylene oxide-modified cashew nut shell phenol product.

[0016] In some embodiments, the composition forming the propylene oxide modified cashew nut shell preferably comprises, by weight parts: 1000 parts cashew nut shell, 750 parts propylene oxide, 10 parts quaternary ammonium salt phase transfer catalyst, 1.5 parts antioxidant, and 2.5 parts acid neutralizer.

[0017] In some embodiments, the quaternary ammonium salt phase transfer catalyst is selected from benzyltrimethylammonium chloride (BTMAC) or tetrabutylammonium bromide (TBAB). In addition to effectively activating cashew nut shells, the quaternary ammonium salt phase transfer catalyst of the present invention avoids the oxidation of double bonds in cashew nut shells, exhibits good compatibility with other components in epoxy grout, simplifies subsequent processing, and leaves no large amount of salt residue.

[0018] In some embodiments, the antioxidant is a compound of phenolic antioxidants and phosphite antioxidants in a 1:1 ratio. Using other existing antioxidants would not effectively prevent oxidative discoloration or would lack good heat resistance and / or UV resistance. The antioxidant compounded by this invention can further improve the yellowing resistance of propylene oxide-modified cashew nut shells while inhibiting oxidative aging during storage, ensuring the long-term stability of the propylene oxide-modified cashew nut shell product. Furthermore, the phenolic antioxidant of this invention is selected from 2,6-di-tert-butyl-4-methylphenol, and the phosphite antioxidant is selected from phosphites.

[0019] In some embodiments, the acid neutralizer is 85 wt% phosphoric acid to neutralize excess quaternary ammonium salt phase transfer catalyst.

[0020] As a second aspect of the present invention, a method for preparing propylene oxide-modified cashew phenol using the above composition is provided, comprising: steps A1-A5.

[0021] Step A1: Add cashew phenol, quaternary ammonium salt phase transfer catalyst, and antioxidant into the reactor.

[0022] Step A2: Inert gas is introduced to replace the air in the reactor and maintain a slightly positive pressure.

[0023] Step A3: Start stirring and simultaneously raise the temperature to the first temperature to mix and activate the quaternary ammonium salt phase transfer catalyst and cashew phenol in the reactor.

[0024] Step A4: After controlling the temperature inside the reactor to rise to the second temperature, add propylene oxide dropwise to carry out the addition reaction.

[0025] Step A5: After aging and vacuum devolatilization, inert gas is introduced to restore normal pressure while cooling to the third temperature. An acidic neutralizing agent is added for neutralization to obtain propylene oxide modified cashew phenol.

[0026] In this invention, a micro-positive pressure inert gas protection process is used throughout the preparation of propylene oxide-modified cashew nut shell powder to protect the addition reaction between cashew nut shell powder and propylene oxide, and the temperature of the addition reaction is controlled. This effectively inhibits the oxidation and discoloration of cashew nut shell powder, reduces the occurrence of side reactions, and obtains a light-colored, yellowing-resistant propylene oxide-modified cashew nut shell powder product. At the same time, it ensures that the product has low viscosity characteristics, which facilitates the subsequent processing and construction of epoxy grout.

[0027] In some implementations, the second temperature is greater than the first temperature, and the first temperature is greater than the third temperature.

[0028] In some embodiments, in step A1, 1000 parts of cashew nut powder, 8-12 parts of quaternary ammonium salt phase transfer catalyst, and 1.2-1.8 parts of antioxidant are added to the reactor.

[0029] In some embodiments, in step A2, an inert gas is introduced into the reactor, and the process of evacuating and purging the reactor with inert gas is repeated at least three times to replace the air inside the reactor and prevent the air from oxidizing and discoloring the double bonds in cashew phenol. The inert gas can be high-purity nitrogen (N2, purity 99.99%). After purging with inert gas, the inert gas acts as a protective gas throughout the process, while maintaining a slightly positive pressure (0.01-0.02 MPa) of the inert gas (such as nitrogen) inside the reactor, laying the foundation for inhibiting the oxidation and discoloration of cashew phenol.

[0030] In some embodiments, in step A3, stirring is started in the reactor to allow the quaternary ammonium salt phase transfer catalyst to mix evenly with cashew phenol and antioxidant. After uniform mixing, the temperature is raised to a first temperature and stirred for 30 min to 1 h, wherein the first temperature is 85-98°C, for example, 85°C, 90°C, 95°C, or 98°C. At this temperature, the phenolic hydroxyl groups in cashew phenol are activated by the quaternary ammonium salt phase transfer catalyst to form active ion pairs.

[0031] Specifically, the mechanism by which the quaternary ammonium salt phase transfer catalyst activates cashew phenol in this invention can be understood as follows: the quaternary ammonium salt phase transfer catalyst forms an ion pair with the phenolic hydroxyl group (Ar-OH) in cashew phenol, enhancing the nucleophilic activity of the phenolic hydroxyl group and generating a stable phenoxy anion (Ar-O). - This provides reactive sites for the ring-opening of propylene oxide. The activation process is mild and does not involve the strong oxidizing effect of strong bases.

[0032] In some embodiments, in step A4, the reactor temperature is raised to a second temperature while the pressure inside the reactor is controlled to be ≤0.25 MPa. The second temperature is 95-105°C, for example, 95°C, 98°C, 100°C, 105°C, or any value within this temperature range. At this second temperature and / or pressure, 720-780 parts of propylene oxide are slowly added to the reactor using a metering pump over a period of 4-5 hours. Slow addition is used to avoid excessively high local concentrations within the reactor, which could trigger side reactions and affect the viscosity of the propylene oxide-modified cashew phenol.

[0033] In some embodiments, in step A5, after the propylene oxide is added dropwise, the temperature inside the reactor is maintained at about 100°C-105°C, the inert gas is kept under a slight positive pressure, and stirring continues to mature until the pressure inside the reactor becomes constant and no longer decreases, thus confirming that the addition reaction is complete. The maturation time is 1-3 hours, preferably 2 hours.

[0034] After the addition reaction is completed, the temperature inside the reactor is maintained at 100℃-105℃, and the vacuum system is turned on to perform deashing treatment to remove the trace amounts of unreacted propylene oxide and the trace amounts of water generated in the reactor. The vacuum deashing is carried out at -0.095MPa to -0.098MPa for 1h-2h, preferably 1h.

[0035] After the vacuum devolatilization process is completed, the vacuum system is shut off, and an inert gas (such as nitrogen) is introduced to restore the pressure to atmospheric level. The temperature inside the reactor is then lowered to the third temperature. 2.0-3.0 parts of an acidic neutralizing agent (such as 85wt% phosphoric acid) are then slowly added to remove unreacted quaternary ammonium salt phase transfer catalyst. The third temperature is 70℃-80℃, for example, 70℃, 72℃, 75℃, 78℃, 80℃, etc. The pH of the product is adjusted to 6.0-7.0 by adding the acidic neutralizing agent, and the neutralization and stirring time is 20min-30min.

[0036] After neutralization, the material is directly added. The resulting propylene oxide-modified cashew phenol product is a light yellow transparent liquid. No additional filtration step is required, and it can be used as a cashew phenol modified diluent for epoxy grout.

[0037] In some embodiments, under the action of a quaternary ammonium salt phase transfer catalyst, the addition molar ratio of propylene oxide to cashew phenol is precisely controlled to be 3-4:1. An addition degree of 3-4 has several advantages: First, it ensures that the molecular chain length of the propylene oxide-modified cashew phenol product is moderate, retaining the toughening properties of the long cashew phenol chain while avoiding molecular chain entanglement caused by a high addition degree. Second, the reaction is mild, reducing byproduct formation and ensuring low viscosity and high fluidity of the product, which is beneficial for balancing the low viscosity characteristics of the propylene oxide-modified cashew phenol product with the epoxy reactivity. Third, it further ensures the smooth application of the propylene oxide-modified cashew phenol as a diluent in epoxy grout sealant, and also allows for sufficient reaction with epoxy resin and amine curing agents, preventing precipitation and whitening after curing.

[0038] The ring-opening addition principle of propylene oxide and cashew nut shell alcohol in this invention is as follows: the phenoxy anion performs nucleophilic attack on the less sterically hindered carbon atom in the three-membered ring of propylene oxide, causing the three-membered ring to open and generating an etherified intermediate containing a hydroxyl group; the hydroxyl group of this etherified intermediate continues to undergo directional ring-opening addition with propylene oxide. By controlling the amount of propylene oxide and cashew nut shell alcohol added, 3-4 propylene oxide molecules can be grafted onto a single cashew nut shell alcohol molecule, thereby forming a modified cashew nut shell alcohol product with isopropoxy groups in the side chain. The overall reaction formula is: Ar-OH + nPO (degree of addition n = 3-4) → Ar-O-[CH(CH3)CH2O] n -H.

[0039] In summary, this invention, in the preparation of propylene oxide-modified cashew nut shells, utilizes the synergistic effect of inert gas protection throughout the process, controlled reaction temperature (such as low-temperature activation, addition, and ripening reactions), and compounded antioxidants to inhibit the oxidative crosslinking of unsaturated double bonds in the cashew nut shell side chains, thus preventing the formation of colored oxides. The presence of antioxidants can capture free radicals during the reaction and storage process, preventing further aging and discoloration of the product and improving its resistance to yellowing.

[0040] As a third aspect of the present invention, a propylene oxide-modified cashew nut shell is provided, which is prepared by the above method, wherein the addition molar ratio of propylene oxide to cashew nut shell is 3-4:1, and the propylene oxide-modified cashew nut shell is a light yellow transparent liquid.

[0041] As a fourth aspect of the present invention, an epoxy grout sealant is provided, comprising, by weight parts: a first component (i.e., an epoxy component) and a second component (a curing agent component), wherein the first component comprises 100 parts epoxy resin, 5-20 parts of propylene oxide-modified cashew nut shell powder as described above, 6-10 parts fumed silica, and 0.1-0.6 parts silicone defoamer; the second component comprises 100 parts amine curing agent, 5-20 parts of propylene oxide-modified cashew nut shell powder as described above, 6-10 parts fumed silica, 5-10 parts titanium dioxide, and 0.1-0.5 parts silicone defoamer.

[0042] In this invention, propylene oxide-modified cashew phenol has light color, high viscosity, and excellent resistance to yellowing. When used as a diluent in the preparation of epoxy grout, it has good compatibility with epoxy and curing agent components, smooth construction, and does not use strong alkalis or other substances, thus exhibiting good environmental friendliness, simplifying the neutralization process, and leaving no large amount of salt residue, making it suitable for the production and application of high-end grout.

[0043] In some implementations, the first component and the second component are mixed in a mass ratio of 1:1. After the mixture is thoroughly mixed and degassed, it can be applied. The curing time is 4-6 hours at room temperature (25°C) and the complete curing time is 24 hours.

[0044] In some implementations, the epoxy resin can be E51 epoxy resin, providing good durability and stain resistance for the epoxy grout.

[0045] In some embodiments, the specific surface area of ​​fumed silica is 200 m². 2 Approximately [amount] g is used to improve the surface smoothness of epoxy grout, while also providing a certain degree of compressive strength. The presence of titanium dioxide can appropriately improve the weather resistance of epoxy grout and prevent discoloration.

[0046] In some embodiments, the amine curing agent includes a modified aliphatic amine curing agent or a polyether amine curing agent, which crosslinks and cures with the epoxy resin.

[0047] In some implementations, the silicone defoamer is selected from BYK A530.

[0048] The technical solutions of the present invention will be described in detail below with reference to specific embodiments. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present invention.

[0049] It should be noted that the five key indicators of the products in the embodiments and comparative examples of this invention, namely color (Gardner value), viscosity (25℃, mPa·s), hydroxyl value (mg KOH / g), yellowing resistance (UV aging for 48h, ΔE (color change)), and compatibility (miscibility with E51 epoxy resin 1:1), were all tested using industry-standard methods.

[0050] Example 1

[0051] The formulation of propylene oxide modified cashew phenol comprises, by mass parts: 1000 parts cashew phenol, 750 parts propylene oxide, 10 parts benzyltrimethylammonium chloride (BTMAC), 1.5 parts antioxidant, and 2.5 parts 85 wt% phosphoric acid, wherein the antioxidant is obtained by compounding 2,6-di-tert-butyl-4-methylphenol and phosphite in a mass ratio of 1:1.

[0052] Method for preparing propylene oxide-modified cashew nut shell powder: Cashew nut shell powder, benzyltrimethylammonium chloride, and antioxidant were added to a high-pressure reactor (hereinafter referred to as "reactor") according to the above-mentioned mass proportions and the reactor was tightly sealed. High-purity nitrogen gas was introduced into the reactor, and the process of vacuuming and nitrogen purging was repeated three times to replace the air in the reactor, ultimately maintaining a slightly positive pressure (0.01-0.02 MPa). Stirring was started for 30 minutes, and the temperature was raised to 90°C to mix BTMAC and cashew nut shell powder in the reactor and activate the phenolic hydroxyl groups in the cashew nut shell powder to form active ion pairs. After controlling the temperature in the reactor to 95°C and the pressure in the reactor to ≤0.25 MPa, propylene oxide was slowly added dropwise to the reactor through a metering pump over a period of 4.5 hours to allow the propylene oxide to undergo a ring-opening addition reaction. After the propylene oxide addition was completed, the temperature was maintained at 100°C and the nitrogen pressure was kept positive, and stirring was continued for 2 hours until the pressure in the reactor became constant and no longer decreased, confirming that the reaction was complete. Maintain the reaction temperature at 100℃, turn on the vacuum system, and perform vacuum devolatilization at a vacuum degree of -0.098MPa for 1 hour to remove unreacted trace amounts of propylene oxide and trace amounts of water generated in the reactor. After the vacuum devolatilization is completed, turn off the vacuum system, introduce nitrogen to restore the pressure to atmospheric level, lower the temperature inside the reactor to 70℃, slowly add 85wt% phosphoric acid, stir and neutralize for 20 minutes, and adjust the pH of the product to 6.0-7.0. After neutralization, discharge the product directly to obtain propylene oxide-modified cashew phenol product. This product is a light yellow transparent liquid that can be used as a diluent for epoxy grout without additional filtration.

[0053] The propylene oxide-modified cashew phenol prepared in Example 1 was tested, and the results were as follows: Gardner value = 1, viscosity = 260 mPa·s, hydroxyl value = 98 mg KOH / g, UV aging for 48 h, ΔE = 1.2, and it was miscible with E51 epoxy resin at a mass ratio of 1:1, clear and without turbidity.

[0054] Example 2

[0055] The formulation of propylene oxide modified cashew phenol comprises, by mass parts: 1000 parts cashew phenol, 720 parts propylene oxide, 8 parts benzyltrimethylammonium chloride (BTMAC), 1.2 parts antioxidant, and 2.0 parts 85 wt% phosphoric acid, wherein the antioxidant is obtained by compounding 2,6-di-tert-butyl-4-methylphenol and phosphite in a mass ratio of 1:1.

[0056] Example 2 uses the same method as Example 1 to prepare propylene oxide modified cashew phenol.

[0057] The propylene oxide-modified cashew phenol prepared in Example 2 was tested, and the results were as follows: Gardner value = 1, viscosity = 225 mPa·s, hydroxyl value = 105 mg KOH / g, UV aging for 48 h, ΔE = 1.3, and it was miscible with E51 epoxy resin at a mass ratio of 1:1, clear and without turbidity.

[0058] Example 3

[0059] The formulation of propylene oxide modified cashew phenol comprises, by mass parts: 1000 parts cashew phenol, 780 parts propylene oxide, 8 parts tetrabutylammonium bromide (TBAB), 1.8 parts antioxidant, and 3.0 parts 85wt% phosphoric acid, wherein the antioxidant is obtained by compounding 2,6-di-tert-butyl-4-methylphenol and phosphite in a mass ratio of 1:1.

[0060] Method for preparing propylene oxide-modified cashew nut shell powder: Cashew nut shell powder, TBAB, and antioxidant are added to a high-pressure reactor (hereinafter referred to as "reactor") according to the above-mentioned mass proportions and the reactor is tightly sealed. High-purity nitrogen is introduced into the reactor, and the process of vacuuming and nitrogen purging is repeated three times to replace the air in the reactor, ultimately maintaining a slightly positive pressure (0.01-0.02 MPa). Stirring is started for 30 minutes, and the temperature is raised to 90°C to allow TBAB and cashew nut shell powder in the reactor to mix and activate the phenolic hydroxyl groups in the cashew nut shell powder, forming active ion pairs. After controlling the temperature in the reactor to 95°C and the pressure in the reactor to ≤0.25 MPa, propylene oxide is slowly added dropwise to the reactor through a metering pump over a period of 5 hours to allow the propylene oxide to undergo a ring-opening addition reaction. After the propylene oxide addition is complete, the temperature is maintained at 100°C and the nitrogen pressure is positive, and stirring is continued for 2 hours until the pressure in the reactor becomes constant and no longer decreases, confirming that the reaction is complete. Maintain the reaction temperature at 100℃, turn on the vacuum system, and perform vacuum devolatilization at a vacuum degree of -0.098MPa for 1 hour to remove unreacted trace amounts of propylene oxide and trace amounts of water generated in the reactor. After the vacuum devolatilization is completed, turn off the vacuum system, introduce nitrogen to restore the pressure to atmospheric level, lower the temperature inside the reactor to 70℃, slowly add 85wt% phosphoric acid, stir and neutralize for 20 minutes, and adjust the pH of the product to 6.0-7.0. After neutralization, discharge the product directly to obtain propylene oxide-modified cashew phenol product. This product is a light yellow transparent liquid that can be used as a diluent for epoxy grout without additional filtration.

[0061] The propylene oxide-modified cashew phenol prepared in Example 3 was tested, and the results were as follows: Gardner value ≤ 1 (near water white), viscosity = 310 mPa·s, hydroxyl value = 92 mg KOH / g, UV aging for 48 h, ΔE = 1.0, and it was miscible with E51 epoxy resin at a mass ratio of 1:1, clear and without turbidity.

[0062] Comparative Example 1

[0063] The formulation of propylene oxide modified cashew phenol comprises, by weight, 1000 parts cashew phenol, 750 parts propylene oxide, 5 parts KOH, and 5.4 parts glacial acetic acid.

[0064] Method for preparing propylene oxide-modified cashew nut shell phenol: Cashew nut shell phenol, KOH, and antioxidant are added to a high-pressure reactor according to the above-mentioned mass proportions and the reactor is tightly sealed. High-purity nitrogen is introduced into the reactor, and the process of vacuuming and nitrogen purging is repeated three times to replace the air in the reactor, ultimately maintaining a slightly positive pressure (0.01-0.02 MPa). Stirring is started for 30 minutes, and the temperature is simultaneously raised to 110℃ to allow the KOH in the reactor to mix with the cashew nut shell phenol and activate the phenolic hydroxyl groups in the cashew nut shell phenol, forming active ion pairs. After controlling the temperature in the reactor to rise to 120℃ and the pressure in the reactor to ≤0.4 MPa, propylene oxide is slowly added dropwise to the reactor using a metering pump over a period of 3 hours to allow the propylene oxide to undergo a ring-opening addition reaction. After the propylene oxide addition is complete, the temperature is maintained at 100℃, and stirring is continued for 2 hours until the pressure in the reactor becomes constant and no longer decreases, confirming the complete reaction. Maintain the reaction temperature at 100℃, turn on the vacuum system, and perform vacuum devolatilization at a vacuum degree of -0.098MPa for 1 hour to remove unreacted trace amounts of propylene oxide and trace amounts of water generated in the reactor. After the vacuum devolatilization is completed, turn off the vacuum system, restore the pressure to normal, lower the temperature inside the reactor to 70℃, slowly add glacial acetic acid, stir and neutralize for 20 minutes, and adjust the pH of the product to 6.0-7.0. After neutralization, discharge the material directly to obtain the propylene oxide-modified cashew phenol product, which can be used as a diluent for epoxy grout.

[0065] The propylene oxide-modified cashew phenol prepared in Comparative Example 1 was tested, and the results were as follows: Gardner value = 7, viscosity = 450 mPa·s, hydroxyl value = 95 mg KOH / g, UV aging for 48 h, ΔE = 5.8, and slight turbidity after being mixed with E51 epoxy resin at a mass ratio of 1:1.

[0066] Comparative Example 2

[0067] The formulation of propylene oxide modified cashew nut shell extract comprises, by weight parts: 1000 parts cashew nut shell extract, 780 parts propylene oxide, 8 parts tetrabutylammonium bromide (TBAB), 1.8 parts antioxidant, and 3.0 parts 85 wt% phosphoric acid, wherein the antioxidant is N-isopropyl-N'-phenyl-p-phenylenediamine.

[0068] Method for preparing propylene oxide-modified cashew nut shell powder: Cashew nut shell powder, TBAB, and antioxidant are added to a high-pressure reactor (hereinafter referred to as "reactor") according to the above-mentioned mass proportions and the reactor is tightly sealed. High-purity nitrogen is introduced into the reactor, and the process of vacuuming and nitrogen purging is repeated three times to replace the air in the reactor, ultimately maintaining a slightly positive pressure (0.01-0.02 MPa). Stirring is started for 30 minutes, and the temperature is raised to 90°C to allow TBAB and cashew nut shell powder in the reactor to mix and activate the phenolic hydroxyl groups in the cashew nut shell powder, forming active ion pairs. After controlling the temperature in the reactor to 95°C and the pressure in the reactor to ≤0.25 MPa, propylene oxide is slowly added dropwise to the reactor through a metering pump over a period of 5 hours to allow the propylene oxide to undergo a ring-opening addition reaction. After the propylene oxide addition is complete, the temperature is maintained at 100°C and the nitrogen pressure is positive, and stirring is continued for 2 hours until the pressure in the reactor becomes constant and no longer decreases, confirming that the reaction is complete. Maintain the reaction temperature at 100℃, turn on the vacuum system, and perform vacuum devolatilization at a vacuum degree of -0.098MPa for 1 hour to remove unreacted trace amounts of propylene oxide and trace amounts of water generated in the reactor. After the vacuum devolatilization is completed, turn off the vacuum system, introduce nitrogen to restore the pressure to atmospheric level, lower the temperature inside the reactor to 70℃, slowly add 85wt% phosphoric acid, stir and neutralize for 20 minutes, and adjust the pH of the product to 6.0-7.0. After neutralization, discharge the product directly to obtain propylene oxide-modified cashew phenol product. This product is a light yellow transparent liquid that can be used as a diluent for epoxy grout without additional filtration.

[0069] The propylene oxide-modified cashew phenol prepared in Comparative Example 2 was tested, and the results were as follows: Gardner value ≤ 1 (near water white), viscosity = 320 mPa·s, hydroxyl value = 94 mg KOH / g, UV aging for 48 h, ΔE = 2.8, and it was miscible with E51 epoxy resin at a mass ratio of 1:1, clear and without turbidity.

[0070] Application examples

[0071] The epoxy grout, by weight, comprises: a first component and a second component, wherein the first and second components are mixed in a 1:1 weight ratio. After thorough mixing and degassing, it is ready for application. The curing time at room temperature (25℃) is 4-6 hours, and the complete curing time is 24 hours. The first component comprises 100 parts E51 epoxy resin, 10 parts propylene oxide-modified cashew nut shell powder (from Examples 1-3), 6 parts fumed silica, and 0.2 parts silicone defoamer (BYK A530). The second component comprises 100 parts polyetheramine curing agent, 10 parts propylene oxide-modified cashew nut shell powder (from Examples 1-3), 6 parts fumed silica, 6 parts titanium dioxide, and 0.2 parts silicone defoamer (BYK A530).

[0072] The propylene oxide-modified cashew phenol from Examples 1-3 above was applied in proportion to prepare epoxy grout, resulting in a white epoxy grout. After application at room temperature, the performance was tested as follows: the application was smooth with no stringing or sagging; after curing, the surface was smooth, highly transparent, without whitening or exudation; after 72 hours of UV aging, there was no obvious yellowing; the epoxy grout layer adhered firmly to the tiles without cracking or peeling, and exhibited excellent toughness.

[0073] In summary, this invention utilizes a quaternary ammonium salt phase transfer catalyst instead of a traditional strong base catalyst, employs a low-temperature, fully inert gas-protected process, and optimizes the addition degree of propylene oxide and cashew phenol, as well as the ratio of antioxidants. The resulting propylene oxide-modified cashew phenol is suitable for use in epoxy grout sealants and achieves the following beneficial effects:

[0074] 1) Excellent light color, suitable for high-end light-colored epoxy grout: It adopts quaternary ammonium salt (such as BTMAC) phase transfer catalysis + low temperature (90-105℃) nitrogen protection + compound antioxidant. The product color Gardner value ≤1, which is light yellow or even close to water white. It completely solves the problem of deep color of traditional strong alkali catalysis products. It can be directly used in the production of high-end grout such as white and light gray, without the interference of base color.

[0075] 2) Excellent resistance to yellowing, ensuring long-term use: The synergistic effect of low temperature and no oxidation reaction + compound antioxidants makes the ΔE of the product after 48h UV aging ≤1.5. After the epoxy grout is cured, it will not show obvious yellowing or aging when exposed to light and air for a long time, maintaining the beauty of the grout layer.

[0076] 3) Excellent compatibility, no whitening or precipitation problems: propylene oxide modified cashew phenol is miscible with E51 epoxy resin and modified cycloaliphatic amine / polyetheramine curing agent, with no turbidity or precipitation. After curing, no small molecules are precipitated, avoiding defects such as whitening, oily surface, and pinholes in the epoxy grout layer, and improving the adhesion between the epoxy grout and the tiles.

[0077] 4) Toughening and crack resistance, improving the mechanical properties of epoxy grout: After the long-chain alkenyl structure of cashew phenol is grafted with propylene oxide, it retains the flexible long-chain characteristics of cashew phenol, which can effectively improve the toughness of epoxy grout after curing, avoid cracking and collapse of epoxy grout layer due to temperature changes and substrate shrinkage, and ensure the integrity of epoxy grout layer.

[0078] 5) Green and low-odor, meeting the environmental protection requirements for home decoration: Based on natural cashew phenol, no strong volatile organic solvents are added during the modification process. After the reaction, trace amounts of unreacted monomers are removed. The product has no irritating odor and no heavy metals or harmful impurities remain, meeting the environmental protection standards for home decoration materials.

[0079] 6) Multifunctional and integrated, replacing multiple traditional diluents: The propylene oxide modified cashew phenol of this invention has three functions at the same time: dilution, toughening and yellowing resistance. It can replace the diluent + toughening agent + anti-yellowing agent in traditional tile grout, simplifying the tile grout formula system and reducing the cost of raw material procurement and production preparation.

[0080] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composition for forming propylene oxide-modified cashew phenol, characterized in that, by weight parts, it comprises: 1000 parts cashew phenol, 720-780 parts propylene oxide, 8-12 parts quaternary ammonium salt phase transfer catalyst, 1.2-1.8 parts antioxidant, 2.0-3.0 parts acid neutralizer.

2. The composition according to claim 1, wherein the quaternary ammonium salt phase transfer catalyst is selected from benzyltrimethylammonium chloride or tetrabutylammonium bromide; The antioxidant is obtained by compounding phenolic antioxidants and phosphite antioxidants.

3. The composition according to claim 2, wherein the phenolic antioxidant is selected from 2,6-di-tert-butyl-4-methylphenol; The phosphite antioxidants are selected from phosphites.

4. The composition according to claim 2 or 3, characterized in that the ratio of phenolic antioxidant to phosphite antioxidant is 1:

1.

5. The composition according to claim 1, wherein the acid neutralizer is 85 wt% phosphoric acid.

6. A method for preparing propylene oxide-modified cashew phenol using the composition according to any one of claims 1-5, characterized in that it comprises: Cashew phenol, quaternary ammonium salt phase transfer catalyst, and antioxidant are added to the reactor; An inert gas is introduced to replace the air inside the reactor and maintain a slightly positive pressure. Start stirring and simultaneously raise the temperature to the first temperature to mix and activate the quaternary ammonium salt phase transfer catalyst and cashew phenol in the reactor; After the temperature inside the reactor is raised to the second temperature, propylene oxide is added dropwise to carry out an addition reaction. After aging and vacuum devolatilization, the inert gas is introduced to restore normal pressure while cooling to a third temperature. An acidic neutralizing agent is added for neutralization to obtain the propylene oxide-modified cashew phenol.

7. The method according to claim 6, characterized in that, The inert gas includes nitrogen; The first temperature is 85-95℃; The second temperature is 95-105℃; The ripening and vacuum devouring temperatures are 100-105°C. The third temperature is 70-80℃; The pH of the propylene oxide-modified cashew phenol is adjusted to 6.0-7.0 using the neutralizing agent.

8. A propylene oxide-modified cashew nut shell powder, characterized in that it is prepared by the method according to claim 6 or 7, wherein the addition molar ratio of propylene oxide to cashew nut shell powder is 3-4:1, and the propylene oxide-modified cashew nut shell powder is a light yellow transparent liquid.

9. An epoxy grout sealant, characterized in that, by weight parts, it comprises: First component: The first component comprises 100 parts epoxy resin, 5-20 parts propylene oxide modified cashew nut shell as described in claim 8, 6-10 parts fumed silica, and 0.1-0.6 parts silicone defoamer; Second component: The second component comprises 100 parts of amine curing agent, 5-20 parts of propylene oxide modified cashew nut shell as described in claim 8, 6-10 parts of fumed silica, 5-10 parts of titanium dioxide, and 0.1-0.5 parts of organosilicon defoamer.

10. The epoxy grout sealant according to claim 9, wherein the first component and the second component are mixed in a mass ratio of 1:1.