CS199099B1 - Process for preparing epoxy resins - Google Patents

Abstract

The continuous preparation of epoxy resins of low, moderate and high molecular weight is carried out from epichlorohydrin, 2,2-bis(4-hydroxyphenyl)propane, alkali metal hydroxide and water without further starting materials. The raw materials are mixed vigorously and continuously in a reactor at rates of from 15 to 50 ms<-1> in a very small space, where they are reacted in a maximum of 5 s at temperatures of from 60 to 180 DEG C. The reaction is optionally continued in a second reactor, in which case it is possible for only a proportion of the reaction participants to be reacted in the first reactor, while the remainder are added in the second reactor. The resultant resins and the effluent can be extracted in countercurrent with water or organic solvents in a pulsation unit.

Description

A process for producing epoxy resins

The invention relates to an improved process for the continuous production of epoxy resins from 2,2-bis- (4-hydroxyphenyl) -propem, epichlorohydrin and an aqueous solution of an alkali metal hydroxide.

Various processes are known for producing epoxy resins in which 2,2-bie- (4-hydroxyphenyl) -propane, epichlarhydrin and sodium hydroxide are usually reacted. Polyglycidyl ethers of 2,2-bis- (4-hydroxyphenyl) -propane are formed. The epoxy resins obtained are usually mixtures of the condensation products of epichlorohydrin and 2,2-bis- (4-hydroxyphenyl) -propane with different condensation steps.

By varying the ratio of 2,2-bis / 4-hydroxyphenyl / -propane and epichlorohydrin may number n, wherein ^E is mfrou d ^Elongated SOLUTION alkyl chain ^I mo ^ poles Menke thus setting requirements torsionally reeling ^d ^ oic weight epoxy resin.

Depending on the size n, low molecular weight epoxy resins n = 0 of medium molecular weight epoxy resins of high molecular weight epoxy resins n are greater than 2.

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It is known that epoxy resins are produced according to - continuously in mixing tanks, but in this process there is a large variation in product quality and yield depending on the space and time of the continuous devices.

Variants using catalysts or solubilizers have been described to improve the effect of the discontinuous process. However, these changes only lead to a partial improvement and partly affect the resin quality, or cause additional problems, such as the separation of solubilizers.

An effective improvement of the continuous processes was achieved by using high-speed agitators as described in several patents (U.S. Pat. No. 376,618, DOS 2,341,303).

On a technical scale, continuous processes for producing epoxy resins work substantially more economically than long-term processes.

A process for the continuous production of low molecular weight epoxy resins has been described in which the resin synthesis is carried out in multiple stages in a cascade mixer (U.S. Pat. No. 2,840,541), wherein a mixture of epichlorohydrin and 2,2-bis- (4-hydroxyphenyl) -propane is reacted. in two to three reaction zones with sodium hydroxide · When using two reaction zones ae 40 to 75%, preferably 65% of the used sodium hydroxide is introduced into the first reaction zone and the rest in the second reaction zone · The throughput in the first reaction zone is 1 mol dian One reaction space · The resin obtained has a molecular weight of about 380 to 420 ·

It is also known that the use of dissolution aids can reduce the residence time in the reaction boilers (U.S. Pat. No. 2,848,439). An aliphatic secondary alcohol serves as a dissolution facilitator. The reaction temperature is between 70 and 80 ° C. The delay is two hours, throughput of 0.23 mol of 2,2-bis- (4-hydroxyphenyl) propane per hour and one reaction space ·

However, the reaction times in the known processes are still very long, so that only small yields can be achieved in relation to space and time. In addition, when using cascade mixers, mixed products are formed in each reaction channel which negatively affect the resin quality.

Cascade mixers with a large number of reaction boilers were used to alleviate these drawbacks. Thus, according to U.S. Pat. No. 2,986,551, у cascading *

mixer with six reactors · Acetone serves as a solubilizer · Alkali epoxide is added in steps of 12.5 to 45% in steps · Delay is 100 to 180 ° C for 3 to 15 minutes in each stage · Resin obtained molecular weight 366 and viscosity 15 Pa.s at 25 ° C ·

U.S. Pat. No. 3,069,434 also operates in cascade with six reactors.

Alcohol Alkali hydroxide is used as a solubilizer

199 099 is added to each stage. The temperature is 50-80 ° C, 10 to 20 minutes delay in each step.

Although the mixing effects are reduced by the large number of reactors and thus the slow reaction of the reactants, very large production facilities are required.

Continuous processes for producing epoxy resins in which the reaction boiler is discharged are more technically advantageous.

All the ^d axis ^D-Tai Tantan known way ^of working with ^b y ^b u3. ^and the auxiliary wefts, as means, solubilizers or amines and are therefore affected by significant deficiencies or having long reaction times and low yields only implemented in relation to space. and time.

The use of dissolution enhancers increases the cost of the process, complicates the processing of the reaction mixture, and usually requires expensive separation operations. In addition, increased safety technology measures are required. In the catalytic processes, in addition to the cost of the catalysts (often amines or quaternary ammonium salts are used), difficulties in separating the catalysts occur, so that the resins are usually of poor quality.

The relatively small flow rates also impose a disproportionately large design of the production facilities or a large number of reactors.

It is an object of the invention to produce low, medium and high molecular weight epoxy resins in an economical manner and in good resin quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a continuous process for the production of epoxy resins which allows large yields with respect to space and time and does not require any addition of epichlorohydrin, 2,2-bis- (4-hydroxyphenyl) -propane, alkali metal hydroxide and water. other starting materials.

This object is achieved according to the invention by reacting a part of the reactants in the reactor, bringing them to the second part and reacting there with a further portion of the reactants.

By concentrating large kinetic energies in the narrowest space, the phase boundaries of the heterogeneous reaction mixture increase extremely. The reaction proceeds very evenly in the reactor with high space-time yield, and by converting the kinetic energy into thermal energy and the reaction heat of the chemical reaction, the reaction system inside the reactor is kept at the desired reaction temperature.

The reactor can be fed both a solution of 2,2-bie- (4-hydroxyphenyl) propane in an aqueous solution of alkali metal hydroxide and epichlorohydrin, as well as a solution of 2,2-bis- (4-hydroxyphenyl) -propane in epichorohydrin. an alkali metal hydroxide solution continuously, wherein resin synthesis takes place in the reactor.

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This is done as follows:

Starting materials 2,2-bis / 4-hydroxyphenyl / -propane, epichlorohydrin and sodium hydroxide are mixed continua ^AL them reactor spade SADI ^{hl 15-2} ms O "\ preferably 20 to 25 ms" ¹ and ^p řívádí to reaction. If appropriate, the product then flows continuously into a second reactor in which the reaction can be completed. The reaction product is then worked up in a known manner.

In an alternative embodiment, a portion of the starting materials epichlorohydrin, 2,2-bis- (4-hydroxyphenyl) -propane and an aqueous solution of sodium hydroxide are fed continuously into the reactor and allowed to react there and fed to a second reactor. of the starting materials and reacted therein · The color reaction product is worked up in a known manner ·

The reaction may further be conducted in a second reactor, which may be heated, since only a small amount of heat is released when the ee is reacted.

Since the reaction mixture acquires a relatively high viscosity very rapidly during the continuous reaction, this requires maintaining the flow of the substance. water or aqueous alkali metal hydroxide solution ·

The process according to the invention outperforms all known continuous and dlcontinuous processes so far · It has all the advantages of continuous processes over discontinuous processes · It does not need 2,2-bls- (4-hydroxyphenyl) -iroaline, epichlorohydrin and aqueous alkali hydroxide solution or added catalysts or prostfofek solubilizers in ^f Orme organic maiden ^p · ouštědla reaction rate is considerably greater than in all previous processes ·

The use of reaction heat and friction heat results in a very favorable energy blister ·

Example 1

A mixture consisting of 55% by weight, 2,2-Bis- / 4-hydroxyphenyl / -propane and 45% by weight with rhydrinu epich ^ ^ edehHvá to ⁸⁰ ° C and k ^ ^ p ^of discontinuous fed to the reactor to simultaneously · the reactor was fed continuously the direction B, consisting of 50% by weight of h ^yd Roxi ^d with sodium ^é him and 5 ^{0% h ENGINE} nose ^t n ^e c ^h of water, where ^a is straight ^from ptode ^ IVa to ⁸⁰ ° C · ^S MES feeds to the reactor in the ratio of component A to B as 2.38 to 1 ·

^Admixing the reaction flows through the reactor until ^p Rácová ^and VA is stfižMu r ^y c ^{hl three} axes 25 m ICEM ^{instance from} SE nas'tav ^{s t} ep ^l OTA 95 ° ^C · ^MES leaves ^of the esophagus ^L reactor and collected in an RA to ^{D and even} after it is processed in the usual manner ·

The epoxy resin thus obtained had the following properties:

epoxy equivalent viscosity / 20 ° C / saponification ^d SLN ^LT E ^L C Nu ^hl or volatiles

198,

45.2 Pa ^ s,

0.11% a

0.23

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The resin fits very well as a casting resin, since it does not hurt the dielectric properties.

Treasure 2

The mixture, consisting of 23.2% of the mono-mono-2,2-bis- (4-hydroxyphenylA-propane), 5.7% of the mono-o-caustic soda and 71.1% of the mono-mono-water, was heated to 98 ° C and continuously fed to the reactor. The current is continuously fed to the reactor epichloThydrin so as to achieve hmoonootního ratio of 2,2-bis- / 4-hydroxyfenylApropanu to epichlorohydrin of 1.75 to 1. The reaction temperature is 100 ° C, the product was treated in the reactor shear chlootí r ^{y 20} m. s ” ¹ .

The reaction prodirict, the liberating reactor, is worked up in a known manner.

The epoxy resin is characterized by the following analytical values:

epoxy equivalent 350, viscosity at 100 ° C 0.75 Pa.s saponifiable chlorine 0.21% a volatile proportions 0.32%

Example 3

The mixture consists of 20% hmoonoot 2,2-bis / 4-hydroxylphenylApropane, 75.4% hmoonoot water and 4.6% hmoonoot caustic leach, pre-fed to 95 ° C, continuously fed to the reactor. Simultaneously introduced into the reactor continuously epichlorohydrin so as to maintain hmoonnosní ratio of 2,2-bis / 4-hydroxyfenylApropanu to epichlorohydrin ^{of 1.88} to 1. In the reactor, the mixture is treated ^and shear ^y r Chlost ^20m. s “ ¹ . The reaction takes place in a reactor at 95 ° C. the product is then sent to a second reactor in which the product is heated to 100 ° C to complete the reaction. After passing through the second reactor, the product is worked up in the usual manner.

The reaction product has the following properties:

epoxy equivalent viscosity at 100 ° C i; , weekly chlorine volatiles,

495,

2.1 Pa * 3j

0.15% and

0.23%.

Example 4

A solution consisting of 51% hmoonoot water, 12.7% hmoonosine caustic leach and 36.3% hmoonoot 2,2-bis (4'-4 '). At the same time, epichlorohydrin is continuously fed into the reactor, the ratio of 2,2-bis- / 4-hydroxyphenylApropane to epichlorohydrin being maintained in the screed of 2.48 to 1. Reaction temperature б

199 099 is 97 ° С «The product ее processes at a cutting speed of 20 m. ¹ · The reaction mixture leaving the reactor is treated in a known manner:

The epoxy resin is characterized by the following analytical values: epoxide equivalent of 1042, saponifiable chlorine below 0.1% and volatile fractions of 0.21%.

Resin is well suited for the production of castor oil carboxylic acid esters.

Example 5

Mixture A, consisting of 55% by weight of 2,2-bis- (4-hydroxyphenyl) -propane and 45% by weight of epiohlorohydrin, is preheated to 60 ° C and continuously fed to the reactor. 50% by weight sodium hydroxide and 50% by weight water, which is also preheated to 80 ° C. The weight ratio A to V is set to 2.58 to 1, but only 60% of the required amount of B is fed to the first reactor. The product is passed through the first reactor to the second reactor, where an additional 40% of the required amount of B is added. in both reactors the reaction temperature is maintained at 95 ° C. The cutting speed is now 15 m. s * ¹ .

Properties of epoxy resin are:

epoxide equivalent 189, viscosity at 20 ° C 36.4 Pa · s, saponifiable chlorine 0.12% and volatiles 0.16%.

Example 6

Mixture A, preheated to 80 ° C, consisting of 38% by weight of 2,2-bis- (4-hydroxyphenyl) -propane and 62% by weight of epiohlorohydrin is fed continuously to the first reactor. At the same time, mixture B, consisting of 46% by weight sodium hydroxide and 52% by weight water · A to В weight ratio is 6 to 1.6 · After passing through the first reactor, the product is mixed in a second reactor and mixed with 12.4% by weight 2,2-bis- 4-hydroxyphenyl / propane, 43.8% by weight sodium hydroxide and 43.8% by weight water and allowed to react. The shear rate in both reactors is 15 m · s ¹ and the reaction temperature is 120 ° C.

After processing, the product has the following properties: epoxy equivalent 187, viscosity at 20 ° C 31.4 Pa.s ₅ saponifiable chlorine 0.21% and volatiles 0.25% ·

Claims (4)

OBJECT OF THE INVENTION Process for producing low, medium and high molecular weight epoxy resins by reaction of 2,2-bis- (4-hydroxyphenyl) -propane, epichlorohydrin, alkali metal hydroxide and water, characterized in that the reactants are mixed continuously, intensively together to form the space in the reactor at a speed of 15 to 50 m @ 2, whereupon they are allowed to react for a maximum of 5 seconds at temperatures of 60 to 180 DEG C. and the reaction is optionally completed with the same delay in a second reactor of the same design or The components are fed to the second reactor and reacted with another part of the reactants. 2. The process of claim 1, wherein the solution of 2,2-bis- (4-hydroxyphenyl) propane is mixed with epichlorohydrin in an alkali metal hydroxide solution and allowed to react. 3. A process according to claim 1, wherein the solution of 2,2-bis- (4-hydroxyphenyl) propane in epichlorohydrin and an aqueous solution are mixed and reacted. Process according to Claims 1 to 3, characterized in that water or an aqueous solution of an alkali metal hydroxide is continuously fed as a diluent.