JPS62172B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing a liquid phenol formaldehyde resin having a benzyl ether bond, low viscosity, and containing little unreacted phenol. Although the modified phenol formaldehyde resin obtained by the production method of the present invention is not limited, it can be used for curing reaction of resin with polyisocyanate having at least two or more isocyanate groups through urethane bonding. It can be used particularly suitably. Therefore, the present invention has application in the industrial field of manufacturing, selling, using, and displaying for sale phenol formaldehyde resins. PRIOR TECHNOLOGY As is well known, phenol formaldehyde resins can be roughly divided into novolac-type phenol formaldehyde resins (hereinafter referred to as novolac resins), which are produced using an acidic catalyst with less than 1 mol of formaldehyde per 1 mol of phenol, and formaldehyde resins. There is a resol type phenol formaldehyde resin (hereinafter referred to as resol resin) which is produced using an alkaline catalyst in a concentration of 1 mole or more. In general, novolak resins are solid at room temperature, and there are few sources of formaldehyde to serve as bonding groups, so it is easy to adjust the molecular weight even when concentrated at high temperatures, but on the other hand, it does not have the property of retaining liquid by itself. Therefore, when producing a cured product using a urethane reaction with a polyisocyanate such as methylene diisocyanate (hereinafter referred to as MDI) or tolylene diisocyanate (hereinafter referred to as TDI), it is necessary to make it into a solution with some kind of solvent or to use propylene as a solution. It is common to use polyether polyol with alkylene oxide such as oxide or ethylene oxide to form a liquid polyhydroxy compound, or to mix it with other polyol components and use it as a liquid mixture. On the other hand, since resol resin has a large formaldehyde component in terms of chemical equivalent, it has a large amount of methylol groups bonded to it, and when heated, a chemical reaction progresses, and it has the property of thermosetting itself and becoming insoluble and infusible. Therefore, in order to concentrate the resin, free moisture is removed at low temperature, but it is necessary to leave a large amount of residual moisture or unreacted monomer to retain the liquid, or to add a solvent to the highly viscous resin after concentration. It is made into a liquid. When producing a cured product using this resol resin, polyisocyanate, and urethane reaction, it contains a solvent and a large amount of water, so when using water, it cures because it generates carbon dioxide gas while forming isocyanate groups and urea bonds. Significantly deteriorates the performance of something. As a prior art that is quite closely related to the present invention, there can be mentioned a method for producing a phenol resin described in Japanese Patent Application Laid-open No. 73094/1983. The gist of this prior art is that in the production process of phenolic resin, there is a first stage step in which phenols and formaldehyde are reacted at pH 8 or higher using an alkaline catalyst, and an acid catalyst is used after the first stage step. PH4～7
This is a method for producing a phenolic resin with a large number of dimethylene ether bonds, which is characterized in that it consists of a second step of reaction. However, since the phenolic resin obtained by this conventional technique is a semi-solid resin, it is impossible to employ it in a situation where it is desired to produce a liquid resin without adding a solvent. Furthermore, other related conventional technologies include:
Examples include those described in JP-A-51-38385. The gist of this prior art is that "1 mole of phenols and 0.5 to 1.0 mole of aldehydes"
mol is subjected to reflux reaction in the presence of sulfuric acid or oxalic acid, then an equivalent amount of barium hydroxide or calcium hydroxide to the previously added acid is added, and then 0.5 to 1.5 mol of an aldehyde and a metal salt consisting of a combination of a weak acid and a weak base are prepared. 1. A method for producing a solid self-curing phenolic resin, which comprises adding and refluxing reaction to perform dehydration condensation. (Here, weak acids include acetic acid, boric acid, etc. whose dissociation constant is
A weak base is one with a dissociation constant of 10 ^-4 or less ^, such as subsalt hydroxide or manganese hydroxide. ). By the way, even in this prior art, since the phenolic resin produced is solid, it is impossible to use a liquid phenolic resin at room temperature as desired. Problems to be Solved by the Invention Therefore, in the prior art, it is liquid at room temperature without the addition of an organic solvent, and the molecular weight distribution is concentrated in the low molecular weight region, so that it always maintains a stable low viscosity at room temperature. However, it has not been possible to provide a phenol formaldehyde resin that can be used in a molding process in a liquid state without adding a solvent. Means for Solving the Problems In the present invention, in order to solve the problems of the prior art described above, phenols and formaldehydes are reacted in an aqueous system with the addition of an appropriate catalyst to perform initial condensation. The step of converting the unreacted monomers and water into a product, and passing the thus obtained initial condensate containing unreacted monomers and water through a heated long tube to vaporize the water and unreacted monomers. , the initial condensate is subjected to a polycondensation reaction in the liquid phase independently of their vaporized products, and the reaction mixture thus obtained is then heated at a temperature of 100°C.
A low-viscosity, unreacted material with a benzyl ether bond is introduced into an atmosphere at a temperature above ℃ and under reduced pressure, and the vaporized water and unreacted monomers are taken out of the system and the polymerized resin component is obtained. A method for producing a liquid phenol formaldehyde resin (hereinafter referred to as benzyl ether type phenol formaldehyde resin) containing less reactive phenol is proposed. The modified benzyl ether type phenol formaldehyde resin obtained according to the method of the present invention has properties intermediate between the above-mentioned two known resins, that is, novolak resin and resol resin, and
For example, in addition to having a benzyl ether bond in its resin structure, it also shares a methylene bond similar to novolak resin and a methylol group like resol resin, and is particularly effective for urethane bonding. What is surprising about the benzyl ether type phenol formaldehyde resin produced by the method of the present invention is that its molecular weight distribution is concentrated in a much lower area than that of conventionally known resins, showing low viscosity, and that there is little unreacted phenol. It is. In other words, as shown in Figure 1, a comparison using GPC (gel permeation chromatography), which measures the molecular weight distribution of resins, shows that conventionally known methods concentrate very much on the high molecular side, yet there is a large amount of unreacted phenol. On the other hand, the benzyl ether type phenol formaldehyde resin according to the present invention has less unreacted phenol while retaining the necessary component peaks, and moreover, the growth of the polymer is suppressed. Therefore, it always exhibits a stable liquid state with low viscosity at room temperature, and there is virtually no need to add a solvent to obtain the desired low viscosity. It's something that doesn't exist. The reason why the modified resin obtained by the method of the present invention is particularly suitable for urethane reactions is that it has a pH range of 3, like novolac resins and resol resins.
It is weakly acidic with a value of 4 to 7, not less than or equal to 8,
It is neither extremely acidic (results in slow curing) nor alkaline (cures too quickly), and the catalyst used in the production of the resin has a mediating catalytic effect as a catalytic reagent to produce the urethane reaction. It seems to be for a reason. To produce the benzyl ether type phenol formaldehyde resin according to the present invention, phenols and formaldehydes are first reacted in an aqueous system with the addition of a suitable catalyst to form an initial condensate. This is quite surprising since, as is well known, the presence of water has heretofore been highly frowned upon in carrying out reactions of this type. It was not only extremely difficult to operate in an anhydrous state as in the past, but also the viscosity of the reaction mixture was high, stirring was difficult, and the consumption of power and human power was significantly large. However, according to the method of the present invention, it has been found that the presence of water contributes to the action as a kind of flushing agent in the next step, thereby significantly speeding up the treatment step. It also has a great effect of suppressing the excessive progress of the initial condensation reaction. Although this initial condensation reaction can be carried out either batchwise or continuously, it is generally preferable to carry out the batchwise process. In the production method of the present invention, the initial condensate containing unreacted monomers and water obtained as described above is passed through a heated long tube to vaporize the water and unreacted monomers. At the same time, the initial condensate undergoes a polycondensation reaction in the liquid phase independently of those vaporized products. When this second step is completed, the reaction mixture thus obtained is introduced into an atmosphere of 100°C or higher and reduced pressure, and the vaporized water and unreacted monomers are taken out of the system, and the condensed resin is removed. The purpose is to obtain
If necessary, the above-mentioned second and third steps can be carried out as a continuous operation in a single long tube. Furthermore, in order to make the entire process continuous, it is also possible to carry out the process as successive steps in a single tube. Example (Example 1) 282Kg of phenol and 287Kg of formalin with a concentration of 47%
was charged into a reaction vessel with stirring. Next, 1.4Kg of lead naphthenate and 0.3Kg of zinc oxide were added and the temperature was raised to room temperature.
The temperature was raised to 100°C in about 60 minutes. at 100℃
The viscosity of the resin after 5.5 hours of reaction was 290 centipoise (hereinafter referred to as CP) at 30°C. Then L=23m, D=0.023m, (L/D=
1000) heated steam with an inlet of 1.5 Kg/cm ² , a middle of 3.5 Kg/cm ² , and an outlet of 3.0 Kg/cm 2 , and heated the product A at a pressure of 0.8 Kg/cm ² and a flow rate of 0.8 Kg/cm ² . Injected at 50Kg/hr. At this time, the evaporation tube at the outlet was set at 60 mmHg to 100 mmHg and 125°C to perform vacuum concentration. The properties of the concentrated resin are viscosity 2500CP/30℃,
Non-volatile content is 85% at 180℃ for 60 minutes, moisture is 1% by Karl Fischer method, free phenol is 5.0% by liquid chromatography, and free formaldehyde is 0.3 by hydrochloric acid hydroxylamine method.
%, methylol group/benzyl ether group=1.1 by IR method. Furthermore, the OH value of the combined phenolic hydroxyl and methylol hydroxyl determined by the acetylation method was 490-500. (Product-I) (Comparative Example 1) After carrying out a condensation reaction under the formulation conditions shown in Table 1, the mixture was heated from 100°C to 125°C in a heated outer shell reaction vessel.
Dehydration was performed under reduced pressure at 100 mmHg. It took about 30 minutes to reach 125°C, and after reaching 125°C, it was immediately discharged, spread widely on a saucer, and cooled while blowing air to obtain a resin of Comparative Example-1. (Examples 2 to 4) In the same manner as in Example 1, resins were reacted and concentrated under the conditions shown in Table 1 to produce products II as shown in Table 1.
~ Got IV.

[Table] (Application example 1) 30 parts of product-I according to Example-1, 12.5 parts of Freon 11 (S-1 manufactured by Daikin Industries) as a foaming agent, 1 part of foam stabilizer L-5420 (manufactured by Nippon Unicar), and 1.1 parts of a mixture of 4-phenylpropylpyridine and dibutyltin dilaurate were mixed as a curing accelerator, 40 parts of methylene diisocyanate (MDI) was added, and the mixture was stirred at high speed to obtain a phenol urethane foam material. At this time, cream time is 10 seconds, rise time is 23
The curing time was 35 seconds, and the resulting foam had a density of 0.019 g/cm ³ and a very uniform foam with a closed cell ratio of 85%. In total, the dimensional change rate of the foam was less than +5% in both the vertical and horizontal directions after being left in an oven at 150°C for 20 hours, and the weight change rate was -1%, making it very stable. (Application Example 2) When compounding Product-III in the same manner as Application Example-1, a foam was produced by adding ammonium polyphosphate powder as a flame retardant in an amount of 7% based on the total amount of resin and polyisocyanate. While known polyether polyol foams rapidly combust and burn out when ignited, this foam exhibited high heat resistance so that even when ignited, it did not burn and was carbonized without a flame. (Application example 3) Silica sand (Australian, Fuka silica sand)
For 100 parts, weigh 1 part of Product IV and 1 part of MDI into a Shinagawa mixer, add 1% of 4-phenylpropylpyridine to the resin as a curing accelerator, and mix for 30 seconds to make a casting model. A test piece was molded. Test method HM-1 established by the Casting Technology Promotion Association
The results of measuring the resistive pressure are shown in Table 2. For comparison, the resin of Comparative Example-1 was mixed with a 60% mixed solvent of ethyl cellosolve acetate and petroleum solvent.
1.3 parts of resin solution dissolved in
75% solution of MDI in organic solvent (Hysol)
A similar strength test was conducted using a mold with 1.3 parts added. As shown in Table 2, the mold strength is sufficient to allow use without the use of organic solvents, there is no odor from organic solvents during molding work, and work circulation is significantly improved, and there is no residual organic solvent in the mold. Therefore, the amount of gas generated at 1000℃ was reduced by 40%.

[Table] (Application example 4) While uniformly mixing 200 parts of silica powder, 2 parts of glass wool, and 2 parts of spirit black, add 100 parts of Product-II and 100 parts of MDI to form a slurry.
The composite was formed by pouring it into a mold. After leaving at room temperature
The transverse rupture strength was measured after 24 hours and was found to be 250 Kg/cm ² . Since this complex does not contain organic solvent, it can be heated at 150℃.
After heat treatment for 60 minutes, the strength was 350 Kg/cm ² , the shrinkage rate was 0%, and the weight change rate was 0%. (Application Example 5) 15 parts of Product-I were mixed with 100 parts of wood flour, and after thorough mixing, 15 parts of MDI was added and mixed. The mixture was placed in a metal frame of 300 x 300 x 5 mm and a pressure of 200 kg/cm ² was applied to obtain a molded product cured at room temperature. The strength of the molded product gradually increased at room temperature, reaching the maximum strength after about 3 hours, and an artificial wooden board could be obtained, and the molded product could be fully used as a building material without the odor of organic solvents. (Application example 6) 20 parts of product-II for 100 parts of aluminum powder
A slurry was prepared by mixing 20 parts of MDI and 20 parts of MDI, and poured into a silicone rubber box model prepared in advance without a curing catalyst. After 30 minutes, the cured product was taken out to obtain a molded product. This material was easy to cut with a knife when the curing reaction had not progressed sufficiently, and the shape could be changed freely. After about 5 hours, the molded product could no longer be cut with a knife and became a very hard molded product, which could be fully used as a mold model for casting or a resin mold for molding. As explained above, the phenol formaldehyde resin for urethane reaction according to the present invention is used not only for foaming but also for foaming.
It is a highly valuable resin that is used in a wide range of applications, including molds, building materials, and sealing, and brings good results. When used for urethane reactions, it is very effective to use it without a solvent when making various molded objects, but it is recommended to dilute it with an organic solvent to lower the viscosity and use it in adhesives, etc. There are no restrictions.

[Brief explanation of the drawing]

Figure 1 compares the phenol formaldehyde resin obtained by the production method of the present invention and a conventional product.
This is a graph showing a GPC chart.

Claims (1)

[Claims] 1. (i) A step of reacting phenols and formaldehyde in an aqueous system with the addition of an appropriate catalyst to form an initial condensate, and (ii) The initial condensate containing unreacted monomers and moisture is passed through a heated long tube to vaporize the moisture and unreacted monomers, and the initial condensate is independent of those vaporized substances. (iii) subjecting the reaction mixture thus obtained to a temperature of 100°C.
A low-viscosity, unreacted material with a benzyl ether bond is introduced into an atmosphere at a temperature above ℃ and under reduced pressure, and the vaporized water and unreacted monomers are taken out of the system and the polymerized resin component is obtained. A method for producing liquid phenol formaldehyde resin with less reactive phenol.