KR100612959B1 - The manufacturing method of resol type phenol resin having the controlled molecular weight - Google Patents

Abstract

The present invention relates to a method for producing a resol type phenol resin having a controlled molecular weight, and more particularly, in a method of producing a resol type phenol resin by condensation polymerization of phenols and formaldehyde under a basic catalyst of a metal hydroxide, Optimized the phenols and formaldehyde to a specific reaction ratio to prepare a methylol phenol precursor having a molecular weight is controlled, then performing a two-step process of polycondensation at a specific reaction temperature and time conditions, such as Compared with the minimized amount of unreacted material, no separate removal and recovery process is required. In particular, the physical properties can be controlled by the regulated molecular weight, and thus various fields such as construction industry, aerospace industry, defense industry and machinery industry It relates to a method for producing a resol-type phenolic resin having a molecular weight applicable to.

Methylolphenol Precursor, Condensation Polymerization, Resol Type Phenolic Resin

Description

 The manufacturing method of resol type phenol resin having the controlled molecular weight             

Figure 1 shows the analysis of the amount of unreacted phenol and formaldehyde according to the change in the reaction molar ratio of phenol and formaldehyde of Examples 1 to 4 of the present invention.

The present invention relates to a method for producing a resol type phenol resin having a controlled molecular weight, and more particularly, in a method of producing a resol type phenol resin by condensation polymerization of phenols and formaldehyde under a basic catalyst of a metal hydroxide, Optimized the phenols and formaldehyde to a specific reaction ratio to prepare a methylol phenol precursor having a molecular weight is controlled, then performing a two-step process of polycondensation at a specific reaction temperature and time conditions, such as Compared with the minimized amount of unreacted material, no separate removal and recovery process is required. In particular, the physical properties can be controlled by the regulated molecular weight, and thus various fields such as construction industry, aerospace industry, defense industry and machinery industry It relates to a method for producing a resol-type phenolic resin having a molecular weight applicable to.

Molding materials using polymer resins such as polystyrene resin (PS), polyurethane resin (PU) and polyepoxy resin (EP) can be used alone or in combination with flame retardants such as halogen-based, phosphorus-based and antimony trioxide to solve the flame retardant problem. Added. However, when such a flame retardant is used, it is known that toxic gases such as hydrogen halide and antimony halide are generated during combustion, and thus, the development movement of resins having a natural heat resistance and flame retardancy, regardless of the use of such flame retardants, is spreading. have. Accordingly, phenolic resins have excellent heat resistance and combustion resistance as organic materials, and thus, they are able to satisfy fire extinguishing standards of various countries.

Phenolic resins are also known as the only plastics that are safe for flames because they generate less smoke and noxious gases during combustion. They do not soften even at high temperatures and do not degrade their strength. Because of this, it is stronger and less deteriorated than other plastics. In addition, it is excellent in light weight, rust prevention, and corrosion resistance compared to metal, and the thermal properties of building interior and exterior materials, mine, and vehicle materials, which are fields that glass-reinforced plastics such as polyester or epoxy do not cope with, are strongly required. Application of the field is expected.

On the other hand, phenol resin is produced by the reaction of phenols and aldehydes, acid and base catalyst is used as the reaction catalyst. In this case, when an acid catalyst is used, a novolac phenol resin is prepared, and when a base catalyst is used, a resol phenol resin is prepared. Such a resol refers to a mixture of small molecules having many methylol groups formed by carrying out the reaction while maintaining a reaction molar ratio of aldehydes / phenols of 1 or more in the presence of a basic catalyst.

Generally, the resol type phenol resin is obtained by reacting phenols with aldehydes under a basic catalyst and neutralizing the condensate obtained, followed by dehydration and cooling. Subsequently, in order to dissolve the solidified resin, it was mixed and dispersed using a solvent, and a hardener was added to cure and used in various fields. In this case, it is important to obtain a final resin in a liquid form because the process of dissolving the solid resin in a highly flammable organic solvent has many problems in terms of safety and environmental issues. In order to synthesize the resol type phenolic resin, the reaction molar ratio of aldehydes is used in the range of 1 mol to 3 mol with respect to the phenols, but a large amount of unreacted aldehydes are left, resulting in work odor, which is undesirable for environmental hygiene. The selection of the appropriate molar ratio of

Due to these problems, many studies have been conducted to remove unreacted phenols and aldehydes, and the most widely known method is steam distillation. However, it takes a long time to completely remove the unreacted substance by steam distillation, and is more effective in removing phenols than aldehydes.

In Japanese Patent Laid-Open No. 8-176404, a step of dissolving a resol-type condensate in a liquid phase and dissolving it in a solvent in the process of adding and dispersing a filler, a releasing agent and a curing agent is required. However, the resulting resol-type condensate has a very high viscosity of 40000 cps at 80 ° C., so the condensate must proceed to the next reaction step while maintaining the temperature before the condensate drops and the viscosity becomes higher. That is, there is a disadvantage in that the physical properties change if not used immediately after the synthesis of the resol-type resin, the synthesis process of the resin and the reaction process using the resin must be carried out continuously, there is a problem that the storage capacity of the synthesized resin is inferior.

In Japanese Patent Laid-Open No. 10-36681, it has been proposed to use a hydrazide compound as an aldehyde deodorant. Aldehydes may be removed by adding an aldehyde catch agent such as urea, but an added aldehyde catch agent may change the physical properties of the resin. The hydrazide compound typically includes R-CO-NHNH ₂ (wherein R represents an aryl group having a hydrogen atom, an alkyl group, and a substituent). It can't get rid of the smell, but it can cause a lot of formaldehyde odor. Therefore, the method of adding the deodorant to remove the aldehydes is not effective.

According to Japanese Unexamined Patent Application Publication No. 58-17211, a large amount generated by adding water to a resin synthesized for removing unreacted phenols and aldehydes and passing it under reduced pressure through a tube previously heated at 100 to 130 ° C. A method of synthesizing the resin while suppressing the overproduction or adhesion of the polycondensation reaction product on the inner surface of the tube wall and performing the dehydration process continuously was proposed. However, this requires a special device and a mechanical operation, so that the reaction process is very difficult and the yield of the resin is low.

As described above, the conventional method of synthesizing the resol-type phenolic resin has various problems such as effective recovery and treatment of unreacted substances generated in excess, problems in the working environment during the reaction process, difficulty in controlling physical properties of the synthesized resin, and deterioration of storage performance. In this situation, development of a more effective method for producing a phenol resin is urgently required.

Accordingly, the present inventors have tried to solve the problems of environmental stability in the process of manufacturing a conventional resol-type phenolic resin, effective recovery and treatment of unreacted materials, control of physical properties of phenolic resin and the like. As a result, a process for producing a methylol phenol precursor having a controlled molecular weight by optimizing phenols and formaldehydes as a specific reaction ratio and a series of two steps of performing condensation polymerization at specific temperature and time reaction conditions As a process, it was found that the separate removal and recovery process is not required by minimizing the amount of unreacted material, and it is found that the control of physical properties is possible by controlling the molecular weight, thereby completing the present invention.

Accordingly, an object of the present invention is to provide a method for preparing a new resol type phenolic resin which is capable of controlling physical properties by controlling the required molecular weight and at the same time environmentally and economically effective.

In the present invention, 0.5-10% by weight of a metal hydroxide catalyst is added to a mixture of formaldehydes / phenols in a molar ratio [F / P] of 1.0 to 2.0, and reacted at a temperature of 60 to 100 ° C. Preparing a methylolphenol precursor,

The manufacturing method of the resol type phenol resin which comprises the process of condensation reaction of the said methylol phenol precursor at 80-150 degreeC for 1.5-3.5 hours is characteristic.

Hereinafter, the present invention will be described in detail.

In general, resol refers to a phenol having 1 or more moles of aldehyde, and when synthesizing a large amount of resol-type phenol resins, 1 to 3 moles of aldehyde are usually used. After mixing the reaction raw materials, a condensation reaction is performed at a temperature range of about 80 to 130 ° C. to thereby prepare a resol type phenolic resin. The above process requires a separate neutralization, removal, and recovery process to form and remove a large amount of unreacted material. Also, the above process requires time-economic loss, catch, hardener, release agent, filler, and the like. The use of the compound was not efficient because it entailed changes in physical properties or required special equipment.

The present invention provides a method for preparing a resol type phenolic resin by reacting phenols and aldehydes under a basic catalyst, optimizing the reaction ratio of the reaction materials of the phenols and aldehydes to prepare a methylol phenol precursor having a controlled molecular weight, A single condensation polymerization process for producing a conventional resol-type phenolic resin in a series of two-step process of condensation polymerization of methylol phenol precursor having a molecular weight adjusted to a specific range under appropriate reaction conditions such as a specific temperature and time. In contrast, the molecular weight of the methylol precursor in which the tri or dimethylolphenol precursor is appropriately adjusted by the optimized reaction ratio is controlled to minimize the amount of unreacted material, and thus does not require a separate recovery and removal process. It is a manufacturing method of the resol type phenol resin which can control physical properties, such as a viscosity, by adjustment.

The following Reaction Scheme 1 illustrates a method for preparing a resol type phenol resin using phenol and formaldehyde as an example of the present invention.

As shown in Scheme 1, the phenol can react with formaldehyde in three places: two ortho and one para with respect to the hydroxyl group of phenol. An empty place to react is called a functional group. At this time, since two functional groups are linear compounds, and three are three-dimensional compounds, the curable resin that needs to be cured to become three-dimensional macromolecules is preferably three functional groups. However, phenols of two functional groups are also useful because partially containing phenols of three functional groups can be made into a three-dimensional structure by using them as crosslinking points. That is, not all phenols need to have three functional groups, and resol-type phenol resins can be produced by mixing a phenol having three functional groups and a phenol having two functional groups required to form a crosslinking point.

The resol-type phenolic resin manufacturing method of the present invention will be described in more detail step by step as follows.

In one step, phenols and formaldehyde, which are reaction materials, are mixed and mixed in a specific molar ratio. Phenols, which are the reaction raw materials, are commonly used in the manufacture of phenol resins. For example, phenol, cresol, and xylsol may be used. Preferably, in consideration of reactivity and curability, phenol or m-cresol may be used. It is good.

In addition, in the present invention, formaldehyde is used among aldehydes, and for example, formaldehyde, paraformaldehyde, polyoxymethylene and the like can be used, and preferably, highly reactive formaldehyde is used. .

Dissolving 1 mole of the formaldehyde generates about 15 kcal of heat, because solvation produces methylene glycol. It is generally assumed that formaldehyde sold as a reagent is made of trioxymethylene glycol, which is polymerized during storage to form a polymer body with methylene glycol, causing precipitation. It contains. Therefore, the temperature control of the initial reaction in the phenol resin synthesis is important.

Phenols and formaldehydes, which are the above reaction raw materials, are mixed and used in a molar ratio [F / P] of 1: 1.0 to 2.0. When the mixing ratio of the formaldehyde is less than 1.0 molar ratio, the amount of methanol groups is not sufficient, and sufficient production is impossible. When the molar ratio is more than 2.0, it is impossible to control the exotherm and molecular weight during the manufacture of the resin, and a large amount of unreacted formaldehyde is generated, resulting in environmental and economic problems in the recovery and removal thereof. It is recommended to minimize the amount of unreacted material by reacting with.

Next, a metal hydroxide is added to the mixture as a catalyst and reacted to prepare a methylolphenol precursor.

The metal hydroxide used as the catalyst is used in a conventional phenol resin, and may be selected from, for example, sodium hydroxide, potassium hydroxide, barium hydroxide and lithium hydroxide as hydroxides of alkali metals or alkaline earth metals. The catalyst is used in an amount of 0.5 to 10% by weight based on the phenols which are the reaction raw materials. When the amount is less than 0.5% by weight, the reaction time is too long, and when the amount exceeds 10% by weight, the physical properties of the phenol resin are excessive. There is a problem with adjustment.

In addition, the reaction temperature for preparing the precursor is preferably maintained at 60 to 100 ℃, if the reaction temperature is less than 60 ℃ reaction time is longer than 30 hours, there is a problem in productivity and if the reaction exceeds 100 ℃ It is desirable to maintain this because the time is too fast to cause side reactions.

Next, the formed methylol phenol precursor is subjected to a condensation polymerization reaction under reaction conditions of a specific temperature and time to form a resol type phenol resin.

In general, the curing of the methylolphenol precursor is caused by a reaction between methylol groups or by a condensation polymerization reaction of a methylol group and a hydroxyl group of phenol. Curing reaction occurs in low molecular weight oligomer resol step, and is formed through hard insoluble Resit step through intermediate Resitol step, and the step of Resitol and Resist in other thermosetting resins It is also divided into. In this case, resol refers to a fusible phenol resin which can be an insoluble resin if the reaction is carried out with sufficient active methylol groups, and resitol is a name attached to an intermediate condensate of a phenol-formaldehyde resin. It refers to the step of not melting, and when it is heated, it softens to exhibit rubbery properties. Resist is a name attached to the final condensate of a phenol-formaldehyde-based resin, and refers to a step that does not melt even when heated, and exhibits insoluble properties in solvents such as alcohol and acetone.

In the condensation polymerization reaction, water and unreacted substances are not removed to perform a neutralization, removal, and recovery process to remove separate unreacted substances. Condensation polymerization is carried out at a reaction temperature of 80 to 150 ℃ for 1.5 to 3.5 hours, if the temperature is less than 80 ℃ condensation reaction time is too long, there is a problem in productivity, if the temperature exceeds 150 ℃ problem that molecular weight is too large Occurs. In addition, when the condensation reaction time is less than 1.5 hours, not only the condensation reaction does not occur sufficiently, but there is a problem that the unreacted material is not completely removed, and when the condensation reaction time exceeds 3.5 hours, the problem of excessively increasing the molecular weight occurs. That is, the above-mentioned condensation polymerization conditions, such as temperature and time, are important requirements of this invention, and it is preferable to maintain the said range.

The progress of the present invention can be seen by the rate of viscosity increase of the reactants, the deceleration rate of phenol (quantification of free phenol) by the analysis of gas chromatography (GC), the average molecular weight, and the clouding point using solubility with water. . The average molecular weight of the resol-type phenol resin synthesized according to the present invention is 500 to 1000 (Column-polystyrene, Solvent-THF), the phenol content is 9.0 wt% or less, the formaldehyde content is 1.0 wt% or less, and the pH is 6.0-7.5 and a viscosity of 6500 cps (Brookfield, 25 degreeC).

When the average molecular weight in the said resol type phenol resin is less than 500, the heat resistance of a resin composition will fall largely, and when it exceeds 1000, there exists a possibility of the moldability problem and the exothermic property of resin itself may be maintained, and it is good to maintain the said range. In addition, by mixing the parasol toluene sulfonic acid aqueous solution (50% by weight) as a curing agent to the resol-type phenolic resin synthesized in the present invention can detect the temperature generated by the progress of the instant curing reaction. Specifically, when 25 wt% of aqueous solution of paratoluenesulphonic acid is added to the phenol resin and stirred to be completely mixed, the temperature rises from the initial stage of the curing reaction, the resol stage, where the viscosity increases rapidly and the temperature gradually rises. This large and hardening begins. Subsequently, in the resist step, the color is completely cured to red color, and the temperature is raised to a maximum of 100 to 140 ° C.

As described above, the resol type phenol resin prepared by performing a specific two-step process different from the conventional single condensation polymerization process according to the present invention does not require a separate removal and recovery process by minimizing the amount of unreacted material. It is possible to control the molecular weight and physical properties, so that it can be applied to a wide range of applications, such as building interior and exterior materials, building materials, and the building industry.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are not intended to limit the present invention.

Example 1

Into the reactor, 26 g of 37% formaldehyde aqueous solution and 28 g of solid phenol were added and mixed at 1.0 / 1 molar ratio (F / P), followed by mixing and stirring.After the solid phenol was completely dissolved, 0.42 g of barium hydroxide as a catalyst was added and purged with nitrogen ( purge). After purging, the reaction mixture was slowly heated to 80 ° C. for 1 hour and reacted for 5 hours. After completion of the reaction, the methylolphenol precursor was separated for one day, and water and the unreacted product were separated by about 12 to 18 g, and the reaction was analyzed by gas chromatography (GC).

The methylolphenol precursor was condensed in a vacuum oven at 120 ° C. to remove water and unreacted formaldehyde, thereby preparing a phenol resin such that the reaction product maintained a solid content of about 85% by weight.

Example 2

In the same manner as in Example 1, a resol-type phenol resin was prepared using a molar ratio (F / P) of formaldehyde to phenol of 1.25 / 1.

Example 3

In the same manner as in Example 1, a resol-type phenol resin was prepared using a molar ratio (F / P) of formaldehyde to phenol of 1.57 / 1.

Example 4

In the same manner as in Example 1, a resol type phenol resin was prepared using a molar ratio (F / P) of formaldehyde to phenol of 1.87 / 1.

Gas chromatography analysis results of the upper water layer and the lower resin layer by separating the methylol phenol precursors prepared in Examples 1 to 4 by layer separation are shown in Table 1 below.

division [F / P] molar ratio layer Phenolic (wt%) Formaldehyde (wt%) Water (wt%) Methylolphenol (% by weight) Example 1 1/1 Water layer 9.2 0 90.8 - Resin layer 6.8 4.1 16.0 73.1 Example 2 1.25 / 1 Water layer 8.9 0.5 90.6 - Resin layer 6.7 4.3 16.9 72.1 Example 3 1.57 / 1 Water layer 8.3 1.0 90.7 - Resin layer 6.0 4.7 15.9 73.4 Example 4 1.87 / 1 Water layer 7.6 1.1 91.3 - Resin layer 5.9 4.8 15.5 73.8

Looking at Table 1, it is found that the water of the formaldehyde solution itself occupies most of the water layer in the upper portion, and the concentration of water is almost constant while increasing the molar ratio of F / P, while the concentration of phenol gradually decreases. Could. This can be interpreted as an increase in the reaction conversion of phenol.

In addition, as the molar ratio of F / P increases, the content of methylolphenol increases and the amount of remaining phenol decreases. The higher the molar ratio of F / P, the more methyl group linkages that can be easily formed to form a multifunctional group. Could. On the other hand, when formaldehyde reacts too much compared to phenol, it is difficult to control the exotherm and molecular weight of the resin itself, and the amount of remaining unreacted formaldehyde gradually increases.

In order to determine the optimum formaldehyde and phenol molar ratio based on the results of Table 1, the result of analyzing the unreacted amount of phenol and formaldehyde according to the molar ratio change of F / P as shown in Figure 1 Indicated.

As can be seen in Figure 1, as the molar ratio of F / P increases the amount of unreacted phenol tends to decrease rapidly, which can be seen that the reaction rate of phenol increases. The most optimal molar ratio of formaldehyde and phenol is 1.4 / 1, which is the molar ratio of F / P at the intersection of formaldehyde and phenol, but at the molar ratio of 1.4 / 1 the amount of unreacted phenol is too high. Many exist. Therefore, it is important to select a molar ratio that minimizes the amount of unreacted phenol in consideration of environmental problems and economics of the reaction raw materials.

Example 5

The molecular weight of the phenolic resin (PF resin) is determined during the condensation process. To determine the change of molecular weight and viscosity according to the condensation reaction time, the molar ratio of F / P is fixed at 1.87 / 1, and the 120 ° C vacuum oven ( The reaction time in a vacuum oven) was changed to 1.5 to 3.5 hours as shown in Table 2 to perform a condensation reaction to prepare a resol type phenol resin. The viscosity and molecular weight of the resol-type phenolic resin according to the condensation time change are shown in Table 2 below.

division F / P molar ratio 120 ℃, condensation time (hours) Viscosity (cps) Molecular Weight Mn Mw Mw / Mn One 1.87 1.5 1500 or less 520 590 1.13 2 1.87 2.0 1500-2500 630 710 1.13 3 1.87 2.5 3000-4000 770 850 1.10 4 1.87 3.0 5000-8000 890 930 1.04 5 1.87 3.5 More than 9000 980 1100 1.12

As shown in Table 2, as the condensation time is increased, the viscosity was increased, the molecular weight was also increased, and even in the distribution index (Mw / Mn) of the molecular weight, it showed a distribution similar to 1.0, which is the most ideal distribution index. It can be said that the molecular weight of the prepared resol-type phenolic resin has almost even distribution without irregularity, so it can be said to be very useful for use as a composite material such as an electronic material which requires a fine material in the future. In addition, since the viscosity and molecular weight of the phenol resin can be variously obtained by controlling the time of the condensation reaction, a resol type phenol resin having a molecular weight and viscosity necessary for various materials can be provided.

As described in Table 1, Table 2 and Figure 1, it was possible to obtain the optimum conditions of the method for synthesizing the resol-type phenolic resin having a suitable molecular weight and physical properties through various conditions change.

 As described above, methylol phenol precursors are prepared by mixing the reaction raw materials in an optimum ratio according to the present invention, and by performing a two-step process of condensation polymerization of these compounds under specific conditions, by minimizing the amount of unreacted materials, Molecular weight and physical properties can be controlled without requiring a recovery process, and the resin can be easily changed to physical properties such as heat resistance, durability, and strength when cured. The interior and exterior walls of transportation means such as interior and exterior materials, sculptures, railways, buses, etc. It is possible to apply a wide range of materials to the overall field of construction materials such as building materials such as materials and other building-related molding materials, aerospace, defense industry, ship, water skiing, canoe, automobile bumper and other mechanical industries.

Claims (4)

To a mixture in which formaldehyde / phenols are mixed at a molar ratio [F / P] of 1.0 to 2.0, 0.5 to 10% by weight of a metal hydroxide catalyst is added to the phenols and reacted at a temperature of 60 to 100 ° C. to methylol phenol. Preparing a precursor, Containing the prepared methylol phenol precursor, condensation reaction for 1.5 to 3.5 hours at a temperature of 80 ~ 150 ℃, A phenolic resin having an average molecular weight of 500 to 1000, a phenol content of 9.0% by weight or less, a formaldehyde content of 1.0% by weight or less, a pH of 6.0 to 7.5, and a viscosity of 6500 cps (25 ° C) is produced. The manufacturing method of the resol type phenol resin whose molecular weight was adjusted to. The method of claim 1, wherein the metal hydroxide is a hydroxide of an element selected from alkali metals or alkaline earth metals. The method of claim 1, wherein the solid content of the product formed by the three-step condensation reaction is maintained in the range of 70 to 90%. delete

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