Alkaline phenolic resin as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of resin materials, and particularly relates to alkaline phenolic resin as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing phenol, bisphenol A and a solvent, adding an alkali liquor A and an alkali liquor B, carrying out a first reaction, adding formaldehyde, carrying out a second reaction, adding the alkali liquor A and the alkali liquor B, and carrying out a third reaction to obtain a product a; adding formaldehyde into the product a, carrying out a fourth reaction, adding alkali liquor A and alkali liquor B, carrying out a fifth reaction, adding formaldehyde, carrying out a sixth reaction, adding alkali liquor A and alkali liquor B, and carrying out a seventh reaction to obtain a product b; adding alkali liquor A into the product b, reacting for the eighth time, cooling, adding urea for reacting for the ninth time, adding an alcohol polymer and a silane coupling agent, and mixing to obtain alkaline phenolic resin; the alkali liquor A and the alkali liquor B respectively and independently represent a potassium hydroxide solution or a sodium hydroxide solution. The tensile strength of the alkaline phenolic resin prepared by the preparation method is 1.29-1.36 MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of resin materials, and particularly relates to an alkaline phenolic resin and a preparation method and application thereof. Background Art

[0002] The method of using alkaline phenolic resin for casting to form a mold (core) is referred to as the α-Set method, which was invented by the British Borden Company in the 1970s. The α-Set method is widely used in Europe, the United States, Japan and other countries and regions, and is often used to produce large and medium-sized steel castings.

[0003] Alkaline phenolic resin has many advantages. Compared with acid-cured self-hardening furan resin, it does not contain sulfur, phosphorus and other elements harmful to castings. It has "secondary curing" and good yield when poured at high temperature, which can prevent thermal cracking of steel castings. At present, it is still one of the most ideal molding (core) materials for steel castings and ductile iron castings.

[0004] However, since the ester-cured alkaline phenolic resin sand process began to be promoted and applied in China in the 1990s, its application is still relatively small, mainly restricted by the following three factors: 1. The tensile strength of the resin is relatively low. In the industry standard JB / T11739-2013 "Self-hardening alkaline phenolic resin for casting", the room temperature tensile strength of the first-class resin is required to be ≥0.8MPa. Among the advantageous products on the market, the tensile strength is basically 0.86-1.02MPa; 2. The viscosity of the resin is high. The viscosity of similar resins on the market is basically above 80mPa·s (25℃), and those with lower viscosity can reach 60mPa·s (25℃). The high viscosity of the resin makes it relatively difficult to mix the sand, and the mixing is uneven, which has a great impact on the performance. 3. The amount of resin added is relatively large, and the modeling cost needs to be reduced.

[0005] Therefore, there is an urgent need to provide a new alkaline phenolic resin having high tensile strength and low viscosity. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides an alkaline phenolic resin and a preparation method and application thereof.

[0007] In order to solve the technical problems existing in the prior art, the present invention provides an alkaline phenolic resin for casting, which has high tensile strength, low viscosity, longer shelf life and is more environmentally friendly.

[0008] A first aspect of the present invention provides a method for preparing an alkaline phenolic resin.

[0009] Specifically, a method for preparing an alkaline phenolic resin comprises the following steps:

[0010] (1) Phenol, bisphenol A and a solvent are mixed, alkali solution A and alkali solution B are added, a first reaction is carried out, then formaldehyde is added, a second reaction is carried out, and then alkali solution A and alkali solution B are added, a third reaction is carried out, and product a is obtained;

[0011] (2) adding formaldehyde to the product a to carry out a fourth reaction, then adding alkali solution A and alkali solution B to carry out a fifth reaction, then adding formaldehyde to carry out a sixth reaction, then adding alkali solution A and alkali solution B to carry out a seventh reaction to obtain product b;

[0012] (3) adding alkaline solution A to the product b to carry out the eighth reaction, cooling, adding urea to carry out the ninth reaction, and then adding an alcohol polymer and a silane coupling agent, mixing, and obtaining the alkaline phenolic resin;

[0013] The alkali solution A and the alkali solution B respectively and independently represent potassium hydroxide solution or sodium hydroxide solution.

[0014] Preferably, the alkali solution A is a potassium hydroxide solution, further preferably, the alkali solution A is a potassium hydroxide solution with a mass fraction of 40-55%, and even more preferably, the alkali solution A is a potassium hydroxide solution with a mass fraction of 45-50%.

[0015] Preferably, the alkali solution B is a sodium hydroxide solution, further preferably, the alkali solution B is a sodium hydroxide solution with a mass fraction of 25-40%, and even more preferably, the alkali solution B is a sodium hydroxide solution with a mass fraction of 30-36%.

[0016] Preferably, the alcohol polymer is polyethylene glycol, more preferably polyethylene glycol 400.

[0017] Preferably, the temperature of the first reaction is 50-65° C., and the reaction time is 10-15 minutes. More preferably, the temperature of the first reaction is 55-60° C., and the reaction time is 10-15 minutes.

[0018] Preferably, the temperature of the second reaction is 55-75° C., and the reaction time is 20-70 minutes. More preferably, the temperature of the second reaction is 60-70° C., and the reaction time is 30-60 minutes.

[0019] Preferably, the temperature of the third reaction is 65-80°C, and the reaction time is 20-70 minutes. More preferably, the temperature of the third reaction is 70-75°C, and the reaction time is 30-60 minutes.

[0020] Preferably, the temperature of the fourth reaction is 55-75° C., and the reaction time is 20-70 minutes. More preferably, the temperature of the fourth reaction is 60-70° C., and the reaction time is 30-60 minutes.

[0021] Preferably, the temperature of the fifth reaction is 65-80°C, and the reaction time is 20-70 minutes. More preferably, the temperature of the fifth reaction is 70-75°C, and the reaction time is 30-60 minutes.

[0022] Preferably, the temperature of the sixth reaction is 55-75° C., and the reaction time is 50-100 minutes. More preferably, the temperature of the sixth reaction is 60-70° C., and the reaction time is 60-90 minutes.

[0023] Preferably, the seventh reaction process is to first react at 75-80° C. for 60-90 minutes, and then heat to 85-90° C. for 60-80 minutes.

[0024] Preferably, the temperature of the eighth reaction is 50-65° C., and the reaction time is 10-40 minutes. More preferably, the temperature of the eighth reaction is 55-65° C., and the reaction time is 10-30 minutes.

[0025] Preferably, the temperature of the ninth reaction is 45-60°C, and the reaction time is 10-20 minutes. More preferably, the temperature of the ninth reaction is 50-55°C, and the reaction time is 10-20 minutes.

[0026] Preferably, the solvent is water.

[0027] Preferably, before the first reaction, the weight ratio of phenol, bisphenol A, solvent, alkali solution A and alkali solution B is 410-460: (55-75): (38-58): (45-55): (10-20). Further preferably, before the first reaction, the weight ratio of phenol, bisphenol A, solvent, alkali solution A and alkali solution B is 410-460: (55-75): 48: (45-55): (10-20).

[0028] Preferably, after the first reaction is completed and before the second reaction begins, the weight of formaldehyde added is 200-300 parts.

[0029] Preferably, after the second reaction is completed and before the third reaction begins, the weight of the added alkali solution A is 35-45 parts, and the weight of the added alkali solution B is 15-25 parts.

[0030] Preferably, after the third reaction is completed and before the fourth reaction begins, the weight of formaldehyde added is 200-300 parts.

[0031] Preferably, after the fourth reaction is completed and before the fifth reaction begins, the weight of the added alkali solution A is 40-50 parts, and the weight of the added alkali solution B is 10-20 parts.

[0032] Preferably, after the fifth reaction is completed and before the sixth reaction begins, the weight of formaldehyde added is 200-300 parts.

[0033] Preferably, after the sixth reaction is completed and before the seventh reaction begins, the weight of the added alkali solution A is 30-40 parts, and the weight of the added alkali solution B is 170-200 parts.

[0034] Preferably, after the seventh reaction is completed and before the eighth reaction begins, the weight of the alkali solution A added is 122-142 parts.

[0035] Preferably, after the eighth reaction is completed and before the ninth reaction begins, the weight of urea added is 7-12 parts.

[0036] Preferably, the weight of the alcohol polymer is 115-145 parts, and the weight of the silane coupling agent is 10-16 parts.

[0037] Preferably, a method for preparing an alkaline phenolic resin comprises the following steps:

[0038] (1) Add 410-460 parts of molten phenol, 55-75 parts of bisphenol A and 38-58 parts of water into a reaction kettle, start stirring, and stir for 10 minutes;

[0039] (2) Add 45-55 parts of alkali solution A to the reactor, and then add 10-20 parts of alkali solution B. Control the temperature at 55-60°C and react for 15 minutes;

[0040] (3) Add 200-300 parts of formaldehyde to the reactor, control the temperature at 60-70°C and react for 30-60 minutes;

[0041] (4) Add 35-45 parts of alkali solution A to the reactor, and continue to add 15-25 parts of alkali solution B, and control the temperature to 70-75° C. to react for 30-60 minutes;

[0042] (5) Add 200-300 parts of formaldehyde to the reaction kettle, control the temperature at 60-70°C and react for 30-60 minutes;

[0043] (6) Add 40-50 parts of alkali solution A to the reactor, and then add 10-20 parts of alkali solution B. Control the temperature at 70-75°C and react for 30-60 minutes;

[0044] (7) Add 200-300 parts of formaldehyde to the reaction kettle, control the temperature to 60-70°C and react for 60-90 minutes;

[0045] (8) Add 30-40 parts of alkali solution A to the reactor, and then add 170-200 parts of alkali solution B. Control the temperature at 75-80°C and react for 60-90 minutes;

[0046] (9) heating to 85°C, and controlling the temperature at 85-90°C for about 60-80 minutes;

[0047] (10) After the first sample is tested for viscosity and it is qualified, the material is cooled to below 60°C;

[0048] (11) Add 31-41 parts of water to the reaction kettle, continue to add 122-142 parts of alkali solution A, control the temperature to 55-65°C and react for 10-30 minutes;

[0049] (12) After the viscosity of the sample is tested for the second time and it is qualified, the material is cooled to below 55°C;

[0050] (13) Add 7-12 parts of urea to the reactor and react at 50-55°C for 20 minutes;

[0051] (14) Add 115-145 parts of polyethylene glycol 400 to the reaction kettle and stir for 15 minutes;

[0052] (15) Cool the material to 45°C, add 10-16 parts of silane coupling agent, and stir for 15 minutes;

[0053] (16) cooling the material to below 40° C., sampling for a third time to test the viscosity and after it is qualified, discharging the material to obtain the alkaline phenolic resin;

[0054] The alkali solution A is a potassium hydroxide aqueous solution with a mass fraction of 45-50%, and the alkali solution B is a sodium hydroxide aqueous solution with a mass fraction of 30-36%.

[0055] Preferably, the qualified range of the first viscosity test is 30-70 mPa.s (25°C), and more preferably 40-60 mPa.s (25°C).

[0056] Preferably, the qualified range of the second viscosity test is 50-90 mPa.s (25°C), and more preferably 60-80 mPa.s (25°C).

[0057] Preferably, the qualified range of the viscosity in the third test is 20-50 mPa.s (25°C), and more preferably 25-45 mPa.s (25°C).

[0058] A second aspect of the present invention provides a basic phenolic resin.

[0059] An alkaline phenolic resin is prepared by the above preparation method.

[0060] The third aspect of the present invention provides an application of an alkaline phenolic resin.

[0061] The application of the above alkaline phenolic resin in the casting field.

[0062] The alkaline phenolic resin and the preparation method thereof of the present invention have the following advantages:

[0063] 1. Solve the problem of low tensile strength of resin (alkaline phenolic resin).

[0064] The use of formaldehyde and alkali solution in steps greatly increases the proportion of resin methylol, the methylol content is high, the phenolic reaction is more complete, and the free phenol and free formaldehyde are lower, thereby significantly improving the resin curing reaction activity, increasing the resin strength, and improving the resin performance.

[0065] 2. Solve the problem of high resin viscosity. High resin viscosity makes sand mixing difficult, thus affecting the use effect.

[0066] The use of alkaline catalysts in multiple steps is beneficial to more complete hydroxymethylation and higher ratio in the addition reaction process; it is beneficial to the resinification process of the polycondensation reaction, and the molecular weight of the polymer is moderate and evenly distributed, thereby achieving low viscosity of the resin.

[0067] 3. Optimize the types and quantities of raw materials, various process parameters, feeding methods, etc. to reduce resin costs and improve resin performance.

[0068] Alkaline catalysts are mixed and added in a suitable ratio, that is, potassium hydroxide and sodium hydroxide are added step by step in a suitable ratio, which changes the current situation of high viscosity and high cost of resin synthesized by a single alkali (potassium hydroxide with a relatively high price). At the same time, the use of mixed alkali is more conducive to increasing the hydroxymethylation ratio during the reaction, controlling the resinization process, reducing the resin viscosity, and reducing the resin cost.

[0069] Experiments have shown that using modified material bisphenol A to partially replace phenol has a significant effect on improving the tensile strength of the resin. The addition of polyethylene glycol (PEG400) plays an important role in extending the shelf life of the resin.

[0070] The object of the present invention is to provide a unique, low-cost, low-viscosity, low-free phenol, low-free aldehyde, high-strength basic phenol-formaldehyde resin for casting and a preparation method thereof.

[0071] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0072] (1) The preparation method of the present invention achieves a significant increase in the hydroxymethylation ratio during the addition reaction and a uniform and easy-to-control resin formation during the polycondensation reaction by adding formaldehyde and alkali solution in batches, thereby ultimately achieving the purpose of improving resin strength, reducing free phenol and aldehyde, and improving product stability.

[0073] (2) By using alkali solution A and alkali solution B in an appropriate proportion as catalysts, the hydroxymethylation process is promoted, which is beneficial to the resinification process of the polycondensation reaction. The molecular weight of the resin is moderate and evenly distributed, thereby achieving the purpose of reducing viscosity, reducing costs, and ensuring stable product quality.

[0074] (3) By optimizing the type and quantity of raw materials, process parameters, feeding method, reaction process control, etc., the product performance can be greatly improved and more environmentally friendly.

[0075] (4) The free formaldehyde content of the alkaline phenolic resin prepared by the preparation method of the present invention is ≤0.05%, which is more than 50% lower than that of similar products on the market; the free phenol content is ≤0.13%, which is more than 40% lower than that of similar products on the market.

[0076] (5) The tensile strength of the alkaline phenolic resin prepared by the preparation method of the present invention is 1.29-1.36 MPa, while the tensile strength of similar products on the market is 0.96-1.02 MPa, which is more than 30% higher.

[0077] (6) The viscosity of the alkaline phenolic resin prepared by the preparation method of the present invention is only 25-45 mPa·s (25° C.), while the viscosity of similar products on the market is 50-150 mPa·s (25° C.), and the viscosity is significantly lower. DETAILED DESCRIPTION

[0078] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0079] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0080] In the following examples, the qualified range of the first viscosity test is 40-60 mPa.s (25°C), the qualified range of the second viscosity test is 60-80 mPa.s (25°C), and the qualified range of the third viscosity test is 25-45 mPa.s (25°C).

[0081] Example 1

[0082] A method for preparing an alkaline phenolic resin comprises the following steps:

[0083] (1) Add 435 parts of molten phenol, 65 parts of bisphenol A and 48 parts of water into a reaction kettle, start stirring, and stir for 10 minutes;

[0084] (2) Add 50 parts of alkali solution A to the reactor, and then add 15 parts of alkali solution B, and control the temperature to 55° C. to react for 15 minutes;

[0085] (3) Add 250 parts of formaldehyde into the reactor and control the temperature to 65°C for 60 minutes;

[0086] (4) Add 40 parts of alkali solution A to the reactor, and then add 20 parts of alkali solution B, and react at 70°C for 30 minutes;

[0087] (5) Add 250 parts of formaldehyde into the reactor and control the temperature to 60°C for 60 minutes;

[0088] (6) Add 45 parts of alkali solution A to the reactor, and then add 15 parts of alkali solution B, and control the temperature to 70° C. to react for 30 minutes;

[0089] (7) Add 250 parts of formaldehyde into the reactor and control the temperature to 70°C for 90 minutes;

[0090] (8) Add 35 parts of alkali solution A to the reactor, and then add 185 parts of alkali solution B, and react at 75° C. for 60 minutes;

[0091] (9) heating to 85° C. and controlling the temperature at 85° C. for about 70 minutes;

[0092] (10) After the first sample is tested for viscosity and it is qualified, the material is cooled to below 60°C;

[0093] (11) Add 36 parts of water to the reactor, continue to add 132 parts of alkali solution A, and control the temperature to 55°C to react for 20 minutes;

[0094] (12) After the viscosity of the sample is tested for the second time and it is qualified, the material is cooled to below 55°C;

[0095] (13) Add 9.5 parts of urea to the reactor and react at 55°C for 20 minutes;

[0096] (14) Add 130 parts of polyethylene glycol 400 to the reaction kettle and stir for 15 minutes;

[0097] (15) Cool the material to 45°C, add 13 parts of silane coupling agent (KH560), and stir for 15 minutes;

[0098] (16) cooling the material to below 40° C., sampling for a third time to test the viscosity and after it is qualified, discharging the material to obtain an alkaline phenolic resin;

[0099] The alkali solution A is a potassium hydroxide aqueous solution with a mass fraction of 48%, and the alkali solution B is a sodium hydroxide aqueous solution with a mass fraction of 34.4%.

[0100] Example 2

[0101] A method for preparing an alkaline phenolic resin comprises the following steps:

[0102] (1) Add 410 parts of molten phenol, 75 parts of bisphenol A and 38 parts of water into a reaction kettle, start stirring, and stir for 10 minutes;

[0103] (2) Add 45 parts of alkali solution A to the reactor, and then add 20 parts of alkali solution B, and react at 55°C for 15 minutes;

[0104] (3) Add 300 parts of formaldehyde into the reactor and react at 70°C for 60 minutes;

[0105] (4) Add 40 parts of alkali solution A to the reactor, and then add 15 parts of alkali solution B, and react at 70°C for 30 minutes;

[0106] (5) Add 200 parts of formaldehyde into the reactor and react at 65°C for 60 minutes;

[0107] (6) Add 40 parts of alkali solution A to the reactor, and then add 20 parts of alkali solution B, and react at 75°C for 30 minutes;

[0108] (7) Add 250 parts of formaldehyde into the reactor and control the temperature to 65°C for 90 minutes;

[0109] (8) Add 40 parts of alkali solution A to the reactor, and then add 170 parts of alkali solution B, and react at 75° C. for 60 minutes;

[0110] (9) heating to 85° C. and controlling the temperature at 85° C. for about 70 minutes;

[0111] (10) After the first sample is tested for viscosity and it is qualified, the material is cooled to below 60°C;

[0112] (11) Add 41 parts of water to the reactor, continue to add 122 parts of alkali solution A, control the temperature at 60°C and react for 20 minutes;

[0113] (12) After the viscosity of the sample is tested for the second time and it is qualified, the material is cooled to below 55°C;

[0114] (13) Add 7 parts of urea to the reactor and react at 50°C for 20 minutes;

[0115] (14) Add 145 parts of polyethylene glycol 400 to the reaction kettle and stir for 15 minutes;

[0116] (15) Cool the material to 45°C, add 10 parts of silane coupling agent (KH560), and stir for 15 minutes;

[0117] (16) cooling the material to below 40° C., sampling for a third time to test the viscosity and after it is qualified, discharging the material to obtain an alkaline phenolic resin;

[0118] The alkali solution A is a potassium hydroxide aqueous solution with a mass fraction of 48%, and the alkali solution B is a sodium hydroxide aqueous solution with a mass fraction of 34.4%.

[0119] Example 3

[0120] A method for preparing an alkaline phenolic resin comprises the following steps:

[0121] (1) Add 460 parts of molten phenol, 55 parts of bisphenol A and 58 parts of water into a reaction kettle, start stirring, and stir for 10 minutes;

[0122] (2) Add 55 parts of alkali solution A to the reactor, and then add 10 parts of alkali solution B, and react at 55° C. for 15 minutes;

[0123] (3) Add 200 parts of formaldehyde into the reactor and react at 65°C for 60 minutes;

[0124] (4) Add 35 parts of alkali solution A to the reactor, and then add 25 parts of alkali solution B, and react at 75°C for 30 minutes;

[0125] (5) Add 300 parts of formaldehyde into the reactor and react at 60°C for 60 minutes;

[0126] (6) Add 50 parts of alkali solution A to the reactor, and then add 10 parts of alkali solution B, and control the temperature to 75°C for 30 minutes;

[0127] (7) Add 250 parts of formaldehyde into the reactor and control the temperature to 65°C for 90 minutes;

[0128] (8) Add 30 parts of alkali solution A to the reactor, and then add 200 parts of alkali solution B, and react at 75°C for 60 minutes;

[0129] (9) heating to 85° C. and controlling the temperature at 85° C. for about 70 minutes;

[0130] (10) After the first sample is tested for viscosity and it is qualified, the material is cooled to below 60°C;

[0131] (11) Add 31 parts of water to the reactor, and continue to add 142 parts of alkali solution A, and control the temperature to 60°C to react for 20 minutes;

[0132] (12) After the viscosity of the sample is tested for the second time and it is qualified, the material is cooled to below 55°C;

[0133] (13) Add 12 parts of urea to the reactor and react at 55°C for 20 minutes;

[0134] (14) Add 115 parts of polyethylene glycol 400 to the reaction kettle and stir for 15 minutes;

[0135] (15) Cool the material to 45°C, add 16 parts of silane coupling agent (KH560), and stir for 15 minutes;

[0136] (16) cooling the material to below 40° C., sampling for a third time to test the viscosity and after it is qualified, discharging the material to obtain an alkaline phenolic resin;

[0137] The alkali solution A is a potassium hydroxide aqueous solution with a mass fraction of 48%, and the alkali solution B is a sodium hydroxide aqueous solution with a mass fraction of 34.4%.

[0138] Comparative Example 1 (relative to Example 1, the number of times formaldehyde and alkali solution are added is reduced)

[0139] A method for preparing an alkaline phenolic resin comprises the following steps:

[0140] (1) Add 435 parts of molten phenol, 65 parts of bisphenol A and 48 parts of water into a reaction kettle, start stirring, and stir for 10 minutes;

[0141] (2) Add 50 parts of alkali solution A to the reactor, and then add 15 parts of alkali solution B, and control the temperature to 55° C. to react for 15 minutes;

[0142] (3) Add 400 parts of formaldehyde into the reactor and control the temperature to 65°C for 60 minutes;

[0143] (4) Add 40 parts of alkali solution A to the reactor, and then add 20 parts of alkali solution B, and react at 70°C for 30 minutes;

[0144] (5) Add 350 parts of formaldehyde into the reactor and control the temperature to 60°C for 60 minutes;

[0145] (6) Add 80 parts of alkali solution A to the reactor, and then add 200 parts of alkali solution B, and control the temperature at 75°C to react for 60 minutes;

[0146] (7) heating to 85° C. and controlling the temperature at 85° C. for about 70 minutes;

[0147] (8) After the first sample is tested for viscosity and it is qualified, the material is cooled to below 60°C;

[0148] (9) Add 36 parts of water to the reactor, continue to add 132 parts of alkali solution A, and control the temperature to 55°C to react for 20 minutes;

[0149] (10) After the viscosity of the sample is tested for the second time and it is qualified, the material is cooled to below 55°C;

[0150] (11) Add 9.5 parts of urea to the reactor and react at 55°C for 20 minutes;

[0151] (12) Add 130 parts of polyethylene glycol 400 to the reaction kettle and stir for 15 minutes;

[0152] (13) Cool the material to 45°C, add 13 parts of silane coupling agent (KH560), and stir for 15 minutes;

[0153] (14) cooling the material to below 40° C., sampling for a third time to test the viscosity and after it is qualified, discharging the material to obtain an alkaline phenolic resin;

[0154] The alkali solution A is a potassium hydroxide aqueous solution with a mass fraction of 48%, and the alkali solution B is a sodium hydroxide aqueous solution with a mass fraction of 34.4%.

[0155] Comparative Example 2 (Changing the Type of Alkali Solution)

[0156] Compared with Example 1, the difference of Comparative Example 2 is that the alkali solution A is a calcium hydroxide aqueous solution with a mass fraction of 41%, and the alkali solution B is a sodium hydroxide aqueous solution with a mass fraction of 34.4%. The rest of the process is the same as that of Example 1.

[0157] Comparative Example 3 (without bisphenol A)

[0158] Compared with Example 1, the difference of Comparative Example 3 is that bisphenol A is not added, and the other processes are the same as those of Example 1.

[0159] Product effect testing

[0160] The free formaldehyde content, free phenol content, viscosity, and tensile strength of the alkaline phenolic resins prepared in the above examples and comparative examples were tested. The test standards and test results are as follows:

[0161] The free formaldehyde content is measured in accordance with HG / T 2622-1994 "Determination of free formaldehyde content in phenolic resin";

[0162] Free phenol is measured according to GB / T 24411-2009 "Phenolic resin for friction materials";

[0163] The viscosity is measured according to the single cylinder rotation viscometer method of GB / T 2794-2022 "Determination of viscosity of adhesives";

[0164] The tensile strength is determined in accordance with the method for determining the room temperature tensile strength of the specimen in Appendix A of JB / T 11739-2013 “Self-hardening alkaline phenolic resin for casting”.

[0165] Table 1: Test results of the embodiments, comparative examples and similar products sold in China

[0166]

[0167]

[0168] As can be seen from Table 1, the alkaline phenolic resins prepared in Examples 1-3 of the present invention have significantly lower viscosity and significantly higher tensile strength than similar products in the industry standard and domestic advanced products, and all indicators have reached the industry leading level.

[0169] In Comparative Example 1, the stepwise addition of formaldehyde and alkaline catalyst is less than that in Example 1, resulting in a significant decrease in the tensile strength of the prepared alkaline phenolic resin, a significant increase in viscosity, and high free formaldehyde and phenol.

[0170] In Comparative Example 2, the type of alkali solution was changed, resulting in a significant decrease in the tensile strength of the prepared alkaline phenolic resin, and significantly higher free formaldehyde and phenol.

[0171] In Comparative Example 3, no modifier bisphenol A was added, resulting in a significant decrease in the tensile strength of the prepared alkaline phenolic resin.

Claims

1. A method for preparing an alkaline phenolic resin, characterized in that: The following steps are involved: (1) Phenol, bisphenol A and a solvent are mixed, alkali solution A and alkali solution B are added, a first reaction is carried out, then formaldehyde is added, a second reaction is carried out, and then alkali solution A and alkali solution B are added, a third reaction is carried out, and product a is obtained; (2) adding formaldehyde to the product a to carry out a fourth reaction, then adding alkali solution A and alkali solution B to carry out a fifth reaction, then adding formaldehyde to carry out a sixth reaction, then adding alkali solution A and alkali solution B to carry out a seventh reaction to obtain product b; (3) adding alkaline solution A to the product b to carry out the eighth reaction, cooling, adding urea to carry out the ninth reaction, and then adding an alcohol polymer and a silane coupling agent, mixing, and obtaining the alkaline phenolic resin; The alkali solution A and the alkali solution B respectively and independently represent potassium hydroxide solution or sodium hydroxide solution.

2. The preparation method according to claim 1, characterized in that: The alkali solution A is a potassium hydroxide solution; the alkali solution B is a sodium hydroxide solution.

3. The preparation method according to claim 1, characterized in that: The alcohol polymer is polyethylene glycol.

4. The preparation method according to claim 1, characterized in that: The temperature of the first reaction is 50-65°C, and the reaction time is 10-15 minutes; and / or, the temperature of the second reaction is 55-75°C, and the reaction time is 20-70 minutes; and / or, the temperature of the third reaction is 65-80°C, and the reaction time is 20-70 minutes.

5. The preparation method according to claim 1, characterized in that: The temperature of the fourth reaction is 55-75°C, and the reaction time is 20-70 minutes; and / or, the temperature of the fifth reaction is 65-80°C, and the reaction time is 20-70 minutes; and / or, the temperature of the sixth reaction is 55-75°C, and the reaction time is 50-100 minutes; and / or, the process of the seventh reaction is first reacting at 75-80°C for 60-90 minutes, and then heating to 85-90°C and reacting for 60-80 minutes.

6. The preparation method according to claim 1, characterized in that: The temperature of the eighth reaction is 50-65° C., and the reaction time is 10-40 minutes; and / or, the temperature of the ninth reaction is 45-60° C., and the reaction time is 10-20 minutes.

7. The preparation method according to claim 1, characterized in that: Before the first reaction, the weight ratio of phenol, bisphenol A, solvent, alkali solution A and alkali solution B is 410-460: (55-75): (38-58): (45-55): (10-20); and / or, after the first reaction is completed and before the second reaction begins, the weight of formaldehyde added is 200-300 parts; and / or, after the second reaction is completed and before the third reaction begins, the weight of alkali solution A added is 35-45 parts and the weight of alkali solution B added is 15-25 parts; and / or, after the third reaction is completed, After the fourth reaction, before the start of the fourth reaction, the weight of formaldehyde added is 200-300 parts; and / or, after the fourth reaction, before the start of the fifth reaction, the weight of alkali solution A added is 40-50 parts, and the weight of alkali solution B is 10-20 parts; and / or, after the fifth reaction, before the start of the sixth reaction, the weight of formaldehyde added is 200-300 parts; and / or, after the sixth reaction, before the start of the seventh reaction, the weight of alkali solution A added is 30-40 parts, and the weight of alkali solution B added is 170-200 parts.

8. The preparation method according to claim 1, characterized in that: After the seventh reaction is completed and before the eighth reaction is started, the weight of the added alkali solution A is 122-142 parts; and / or, after the eighth reaction is completed and before the ninth reaction is started, the weight of the added urea is 7-12 parts; and / or, the weight of the alcohol polymer is 115-145 parts, and the weight of the silane coupling agent is 10-16 parts.

9. A basic phenolic resin, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the alkaline phenolic resin prepared by the preparation method according to any one of claims 1 to 8 in the field of casting.

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