阅读说明：本技术 一种液体酚醛树脂及其制备方法 (Liquid phenolic resin and preparation method thereof ) 是由 郑皆如 申同伟 王锦程 王文浩 于 2020-07-16 设计创作，主要内容包括：本发明公开了一种液体酚醛树脂,由如下质量百分比的组份混合制备得到：苯酚40～50％、甲醛45～57％、碱性催化剂0.5％～1.0％、糠醇1.0～3.0％、尿素0.5～2.0％,硅烷偶联剂0.01～0.5％。本发明中的液体酚醛树脂与粉体酚醛树脂、磨料和填料经混料、成型、固化制成切割砂轮,由于液体酚醛树脂的pH值调节为中性,所含硅烷偶联剂能改善树脂与无机磨料间的界面性能,而且选用含有疏水性能优良的疏水剂粉体酚醛树脂与之共同作为砂轮的粘结剂,所制的砂轮在运输、储存过程中能够防止空气中的水汽侵入磨料与树脂结合剂的缝隙中,减轻树脂的降解速度和界面剥离速度,使砂轮的抗衰退性能大大提高。(The invention discloses a liquid phenolic resin which is prepared by mixing the following components in percentage by mass: 40-50% of phenol, 45-57% of formaldehyde, 0.5-1.0% of an alkaline catalyst, 1.0-3.0% of furfuryl alcohol, 0.5-2.0% of urea and 0.01-0.5% of a silane coupling agent. The liquid phenolic resin, the powder phenolic resin, the grinding material and the filler are mixed, molded and cured to prepare the cutting grinding wheel, the pH value of the liquid phenolic resin is adjusted to be neutral, the silane coupling agent can improve the interface performance between the resin and the inorganic grinding material, the hydrophobing agent powder phenolic resin with excellent hydrophobic performance and the hydrophobing agent powder phenolic resin are selected to be used as the binder of the grinding wheel, and the manufactured grinding wheel can prevent water vapor in the air from invading into the gap between the grinding material and the resin binder in the transportation and storage processes, so that the degradation speed and the interface stripping speed of the resin are reduced, and the anti-fading performance of the grinding wheel is greatly improved.)

1. The liquid phenolic resin is prepared by mixing the following components in percentage by mass: 40-50% of phenol, 45-57% of formaldehyde, 0.5-1.0% of an alkaline catalyst, 1.0-3.0% of furfuryl alcohol, 0.5-2.0% of urea and 0.01-0.5% of a silane coupling agent.

2. The liquid phenolic resin of claim 1, wherein the basic catalyst is an inorganic catalyst.

3. The liquid phenolic resin of claim 1, wherein the basic catalyst is one or more of NaOH, KOH or ammonia water.

4. The liquid phenolic resin as claimed in claim 1, wherein the silane coupling agent is selected from one or more of vinyltriethoxysilane, vinyltrimethoxysilane and vinyltris (β -methoxyethoxy) silane.

5. A process for the preparation of a liquid phenolic resin according to any one of claims 1 to 4 comprising the steps of:

(1) adding a certain amount of phenol, formaldehyde and an alkaline catalyst into a reaction container, carrying out addition condensation polymerization reaction at a constant temperature of 85 +/-1 ℃, cooling when the water solubility ratio reaches 80-100%,

(2) adjusting the pH value to 6.5-7.5, adding urea for polycondensation reaction, then dehydrating under vacuum and negative pressure until the viscosity is 1200-1600 cps,

(3) adding furfuryl alcohol for modification, adjusting the viscosity range to be unchanged, finally adding a silane coupling agent, uniformly stirring, cooling, discharging and storing to obtain the liquid phenolic resin.

6. The method according to claim 5, wherein in the step (1), the temperature is reduced to 50 ℃ or lower.

7. The preparation method according to claim 5, wherein in the step (2), acid or alkali is added to adjust the pH value, and then urea is added to perform polycondensation reaction for 20-30 minutes.

8. The anti-fading cutting grinding wheel is prepared from the following components in parts by weight: 90-110 of No. 46 calcined brown corundum, 90-110 of No. 60 calcined brown corundum, 15-20 of cryolite powder, 8-12 of iron sulfide, 0.5-1 of carbon black, 40-50 of powdered phenolic resin and 10-15 of liquid phenolic resin according to any one of claims 1-4.

Technical Field

The invention belongs to the technical field of industry, relates to the technical field of grinding tools, and particularly relates to a liquid phenolic resin for an anti-fading cutting grinding wheel and a preparation method thereof.

Background

The cutting grinding wheel is the most important grinding tool in the bonded grinding tools, and is the largest grinding tool in use amount and the widest use range. When the grinding wheel is used, the grinding wheel rotates at a high speed, and can perform grooving, cutting and the like on metal or nonmetal materials. The properties of the grinding wheel are mainly determined by the types and the granularity of the grinding materials, bonding agents, fillers, tissues, shapes, sizes and other factors. The abrasive is the main raw material for manufacturing the grinding wheel and is responsible for cutting work. Therefore, the abrasive must be sharp and have high hardness, good heat resistance and a certain toughness.

The cutting grinding wheel product made of the traditional phenolic resin generally has the problems of reduced cutting performance and the like of the grinding wheel product due to the action of external factors such as water vapor, light, ozone and the like in the transportation and storage processes. The cutting performance of the grinding wheel is reduced, namely grinding wheel recession, generally, the time span from production to use of a customer of the cutting wheel is from several weeks to several months, a period of some outlet grinding wheels is even from half a year to more than one year, due to the influence of ambient temperature, humidity and light in the transportation and storage processes, the cutting performance of the cutting wheel is reduced by 30-40% in one month after production, and is reduced by about 50% in three months, so that great loss is caused to both a manufacturer and the customer. At present, the mode of vacuum plastic package and preservation in the shade has been generally adopted in the market, and the recession speed of the grinding wheel is reduced, but the problem is not thoroughly solved by the method.

Disclosure of Invention

In order to solve the problems, the invention aims to provide a liquid phenolic resin for an anti-recession abrasive cutting wheel and a preparation method thereof.

In order to achieve the above object, the present invention provides the following technical solutions: the liquid phenolic resin is prepared by mixing the following components in percentage by mass: 40-50% of phenol, 45-57% of formaldehyde, 0.5-1.0% of an alkaline catalyst, 1.0-3.0% of furfuryl alcohol, 0.5-2.0% of urea and 0.01-0.5% of a silane coupling agent.

The alkaline catalyst is an inorganic catalyst, preferably NaOH, KOH or ammonia water.

The silane coupling agent is selected from one or a mixture of A151 (vinyl triethoxysilane), A171 (vinyl trimethoxysilane), A172 (vinyl tri (beta-methoxyethoxy) silane) and the like.

The invention also provides a preparation method of the liquid phenolic resin, which comprises the following steps:

(1) adding a certain amount of phenol, formaldehyde and an alkaline catalyst into a reaction container, carrying out addition condensation polymerization reaction at a constant temperature of 85 +/-1 ℃, cooling when the water solubility ratio reaches 80-100%,

(2) adjusting the pH value to 6.5-7.5, adding urea for polycondensation reaction, then dehydrating under vacuum and negative pressure until the viscosity is 1200-1600 cps,

(3) adding furfuryl alcohol for modification, adjusting the viscosity range to be unchanged, finally adding a silane coupling agent, uniformly stirring, cooling, discharging and storing to obtain the liquid phenolic resin.

In the step (1), the temperature is reduced to below 50 ℃; preferably 40 to 50 ℃, otherwise the free phenol and the solid content are too high or too low.

And (3) in the step (2), adding acid or alkali to adjust the pH value, and then adding urea to perform polycondensation reaction for 20-30 minutes, wherein the acid is selected from formic acid or boric acid.

In the invention, the addition amount of urea is 2.5-3.5% of the mass of phenol, so that free aldehyde in the resin is reduced to a great extent, but excessive urea-formaldehyde resin cannot be generated, and the product performance is reduced; the adding amount of the furfuryl alcohol is 2.5-3% of the mass of the resin, so that the dissolubility of the resin powder is effectively improved when the furfuryl alcohol is taken as a raw material and powder resin for ageing.

The furfuryl alcohol is colorless or light yellow transparent liquid; slightly pungent in taste, miscible with water, but unstable in water; it is very soluble in organic solvents such as alcohol and ether, but insoluble in paraffin. Furfuryl alcohol is easily resinated when it meets acid, and when it is stored in air, its colour becomes dark due to condensation.

The anti-fading cutting grinding wheel is prepared from the following components in parts by weight: 90-110 # of calcined brown corundum, 90-110 # of calcined brown corundum 60, 15-20% of cryolite powder, 8-12% of ferric sulfide, 0.5-1% of carbon black, 40-50% of powdered phenolic resin and 10-15% of liquid phenolic resin.

The powder phenolic resin is prepared by pulverizing solid resin and hexamethylenetetramine according to the mass ratio of 160-180: 20-30, preferably 173: 27, wherein the solid resin is prepared by mixing the following components in percentage by mass: 55-65% of phenol, 30-40% of formaldehyde, 1.0-1.5% of an acid catalyst, 3-5% of water and 0.1-0.5% of a hydrophobic agent.

The powder phenolic resin is prepared by crushing solid resin and hexamethylenetetramine according to the mass ratio of 173: 27, wherein the solid resin is prepared by mixing the following components in percentage by mass: 55-65% of phenol, 30-40% of formaldehyde, 1.0-1.5% of an acid catalyst, 3-5% of water, 0.05-0.2% of a defoaming agent and 0.1-0.5% of a hydrophobic agent.

The acidic catalyst is an organic catalyst, preferably oxalic acid or citric acid; the hydrophobic agent is selected from one or a mixture of more of fluorine-containing silicone oil, a reactive hydrophobic interface modifier and the like; (ii) a The defoaming agent is selected from silicone defoaming agents and polyether defoaming agents.

The preparation method of the powder phenolic resin comprises the following steps:

(1) putting a certain amount of phenol and an acid catalyst into a reaction vessel, adding formaldehyde at the temperature of 90-95 ℃, carrying out reflux reaction for 1.5-2.5 hours at the temperature of 100-102 ℃,

(2) then dehydrating under normal pressure until the temperature reaches 145-155 ℃, then dehydrating under vacuum until the temperature reaches 165-175 ℃, preserving the heat for 1.5-2.5 hours at 165-175 ℃, and meeting the requirements when the free phenol reaches less than or equal to 1.5 percent and the fluidity reaches 25-35 mm,

(3) adding a hydrophobing agent, uniformly stirring, discharging and flaking to obtain thermoplastic phenolic resin, adding hexamethylenetetramine, and powdering to obtain powdery phenolic resin for the grinding wheel;

preferably, after the vacuum dehydration in the step (2) is carried out until the temperature reaches 165-175 ℃, adding a proper amount of defoaming agent, and continuously carrying out heat preservation and vacuum for a period of time.

The invention has the advantages that:

the liquid phenolic resin, the powder phenolic resin, the grinding material and the filler are mixed, molded and cured to prepare the cutting grinding wheel, the pH value of the liquid phenolic resin is adjusted to be neutral, the silane coupling agent can improve the interface performance between the resin and the inorganic grinding material, the powder phenolic resin containing the hydrophobic agent with excellent hydrophobic performance and the powder phenolic resin are selected to be used as the binder of the grinding wheel, and the manufactured grinding wheel can prevent water vapor in the air from invading into the gap between the grinding material and the resin binder in the transportation and storage processes, so that the degradation speed and the interface stripping speed of the resin are reduced, and the anti-fading performance of the grinding wheel is greatly improved. The liquid phenolic resin of the invention is added with the silane coupling agent with the mass of 1.5-2.5 per mill of the resin, so that the caking property between the resin and the inorganic abrasive material is well enhanced during the material mixing, the stability of the grinding wheel product is stronger, and the rotary strength and the cutting performance of the cutting grinding wheel are improved.

Detailed Description

The above-described scheme is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes and are not intended to limit the scope of the present invention. The conditions used in the examples may be further adjusted according to the conditions of the particular manufacturer, and the conditions not specified are generally the conditions in routine experiments.