KR810001879B1 - Process for the preparation of phenol-formaldehyde foams - Google Patents

Abstract

A resol resin prepd. from 2 mols. phenol and 3-6 mols. HCHO with a basic catalysts, having viscosity 8-60 P, and contg. 70-95% solids was mixed(45-75%) with 25 - 55% novoalk resin(viscosity 5-300 P) contg. a blowing agents, phenolsulfonic acid, and, in some cases, phenol, and the mixture was used to prepd. homogeneous foams with uniform cell structure and no shrinkage. The relative amts. of resol and novolak resins det. the d. of the foams.

Description

Method for preparing phenol-formaldehyde foam

The present invention relates to a process for the preparation of phenol-formaldehyde foams.

According to the conventional method, an anhydrous novolac resin composed of a homogeneous resol phase having a viscosity of 200 to 250 poise at 20 ° C, and a thick solution and composed of methylene chloride (foaming agent), phenol-sulfonic acid (catalyst) and novolak resin The phenol-formaldehyde manufacturing method which mixes at the temperature of 15 degreeC to about 650 degreeC in "mixed tofu" is demonstrated.

The inventors have found that to obtain an extremely homogeneous phenol-formaldehyde foam through its exclusive use using the technique as described above, it is preferable to use a homogeneous resol phase with a significantly lower degree of gum, while the novolac phase is obtained. It was surprising that the foam had no effect on the "homogeneity".

Therefore, according to the present invention, a homogeneous resol phase having a viscosity of about 8 to about 60 poise (viscosity measured at 20 ° C.) and a solid content of 70 to 90% by weight is used, and the resol contained in the homogeneous resol phase is basic. Using a catalyst, the molar ratio of phenol and formaldehyde is obtained by polycondensation of a mixture of 1: 1.5 to 1: 9.

Resol is usually obtained by mixing a phenol and formaldehyde solution in a reactor with the proper proportion of phenol and formaldehyde, followed by heating and boiling of the mixture, followed by the introduction of a basic catalyst (e.g. sodium hydroxide) slowly, Continue boiling for a period of time, then cool and neutralize the mixture with acid (eg acetic acid). Using this known production method, the viscosity of the resol phase (visible in this specification) can be achieved by changing the condensation period or by changing the molar ratio of phenol / formaldehyde or by changing the water content of the phenol phase or by adding a small amount of methanol. Are all BrookFeed viscosity).

The solids content of the resol phase is measured by drying 4 g of this resol phase, weighed in a dish and heated to 140 ° C. in a ventilated oven for 3 hours. The ratio of the amount of product (g) remaining in the dish to the original weighed 4 g is the solids content. This solids content is expressed in% of the original product.

This resol phase contains a surfactant which affects the homogeneity of the obtained mover. Cemulsol B may be used in proportions by weight per 98 parts by weight of the initial resol phase. The resol phase may contain a small amount of methanol, if necessary, up to 10 weights of methanol. The metal-on acts to enhance the guarantee period of the resol phase. This addition leads to an interesting phenomenon in which the viscosity of the resol phase is reduced. Thus, when using the resol whose viscosity is 30 poise at 20 degreeC, when 6 parts of methanol are added with respect to 94 parts of resol, the viscosity will fall to 8 poise.

The resol used contains more than the required amount of formaldehyde. This is because this resol produces 1.9 to 3 moles of formaldehyde per mole of phenol. Thus, especially for the highest formaldehyde phenol ratios (e.g. 2.5 to 3), it can be seen that excess formaldehyde is present and therefore gives an irritating odor to the product itself. In this case, it is advisable to add a substance such as urea, ammonia, sodium sulfite or oxidizing agent on the resol to mask this excess formaldehyde.

According to the present invention, a homogeneous anhydrous noblock phase is used, and the viscosity thereof can be varied within a range of, for example, about 5 to about 300 poise (20 ° C.), and a molar ratio of 2: 1 to 10 to 30% by weight of the foaming agent. To 60 to 90% by weight of a mixture composed of a gin novolak resin obtained by polymerizing a mixture of phenol and formaldehyde of 6: 1 with an acid catalyst, and about 30% by weight of the novolac phase and the novolac phase. It is used as a catalyst and contains 5 to 10% by weight of phenol sulfonic acid based on the total amount of the mixture of the resol phase and the novolac phase.

Furthermore, the relative amounts of resol phase and novolac phase used in mixing are such that the resol phase is 45 to 75% by weight relative to the weight of the final mixture.

Novolak resins are usually obtained by mixing an appropriate relative amount of phenol and formaldehyde aqueous solution in a reactor, which is heated and boiled for a certain period of time by addition of a suitable acid catalyst (e.g. sulfuric acid). The mixture is cooled and the excess contained phenol in the mixture removes the moisture contained by azeotropic distillation. The phenol sulfonic acid acting as a catalyst for foam formation, the phenol used for dilution of novolac phase and the foaming agent are added to the secondary jinnovolac obtained in this way and converted into the novolak phase used in the present invention.

When substantially equal amounts of these two phases are used (eg 45 to 55% by weight) when mixing the resol and the novolak phase, the novolox phase is 60 to 70% by weight of the novolac resin, 10 to 15% by weight of phenolsulfonic acid 16 to 23% by weight of the foaming agent is preferably adjusted.

The novolac phase has a molar ratio of 2: when these two phases are used in a substantially different amount, such as the resol phase 65 to 57% by weight relative to the 35 to 25% by weight of the novolac phase, when mixing the resol and novolac phase ＂Novolak resin＂ 50 to 60% by weight, consisting of 40 to 90% by weight of the phenol novolak resin and 60 to 40% by weight of the phenol no. 1 to 6: 1 mixture obtained by copolymerizing a mixture of phenol and formaldehyde with an acid catalyst, phenolsulfonic acid 20 To 30% by weight, 16 to 23% by weight of the foaming agent, it is preferred that the composition.

In all these cases, foaming agents may be methylene chloride, chloroform, trichloroethylene or 1,1,1, -trichloroethane, and also mixtures of these chlorides with other chlorides or at least one of these chlorides and ethyl It is also possible to use mixtures with alcohols. It is preferable to use a mixture of trichloroethane and ethanol, in particular a mixture of 40 parts by weight of ethanol with respect to 60 parts by weight of trichloroethane in these mixtures. Use of such a mixture further lowers the viscosity of the novolac phase compared to using only trichloroethane itself, whereas using only ethanol alone does not yield adequate foam.

Either phase or the other of the two phases used to carry out the invention may contain surfactants that affect the homogeneity of the foamed tissue as is known in the phenol-formaldehyde foam manufacturing art.

It is prepared by mixing the above two phases of the foam and spraying the mixture onto the surface or the inner space which forms the foam by natural or simultaneous change in the mixture. The relative amounts of these two phases are substantially the same. That is, for example, each phase occupies 45-55% of the mixture.

The temperature at which these two phases are mixed is a critical factor for the properties of the finished product, which, according to the invention, should be between 15 and 65 ° C. Moreover, it is not necessary to heat these two phases to the same temperature when mixing these two phases, while the temperature of the novolak phase (catalyst containing phase) should be slightly higher than the temperature of the resol phase.

The residence time (in the mixed tofu) of the mixture can vary from about 5 seconds to about 1 minute 30 seconds, which of course depends on the reactants themselves and the temperature at which the mixture is produced. It is necessary to adjust the residence time of the mixture in the tofu head when the mixture emerges from the mixed tofu head or after a short time the foaming phenomenon occurs.

It is possible to make certain adjustments to the properties of the obtained foam, in particular its density, in accordance with the change in the relative amounts of the resol phase and the novolac phase when mixing all other than the two phases.

When the present invention is described as an embodiment as follows.

Example 1

[Production of Resol Phase]

Phenol and formaldehyde are introduced into a reactor equipped with a stirrer, a heater and a cooler. The mixture is heated to 50 ° C. and sodium hydroxide (sodium hydroxide solution of 48% concentration) is introduced at this temperature. The reaction is exothermic and the temperature is raised to the boiling point, which reaches about 30 minutes. At this temperature, the mixture is allowed to stand for a period of time to react, followed by distillation of water in vacuo and cooling to 50 ° C. Neutralize to about 7 with 50% acetic acid and maintain the amount of moisture required to obtain a homogeneous resol phase with the desired viscosity. In this way, the resol phase shown in Table I was obtained.

The obtained resin does not contain a phenol phase, and its reactivity (° C./min) is mixed by diluting 100 g of the resin with 10 g of ethyl alcohol at 20 ° C. and adding 10 cm ³ of 50% sulfuric acid (H ₂ SO ₄ ) in 1 minute. It is measured by recording the temperature change as a function of time by putting the whole mixture into a heat insulation container.

Phase R ₁₀ contains 6% by weight of methanol added after the end of the condensation reaction. In general, the resol phase (formaldehyde / phenol = 2.2 to 3) rich in formaldehyde components has proved to be extremely useful in the practice of the present invention in some cases even if a certain amount of formaldehyde is released during foam formation.

The resol phase used in this example was obtained by adding the weight% of the surfactant (Cemulsol B) to the aforementioned resol.

Example 2

[Production of Novolak Resin]

4700 g (50 moles) of phenol at 50 ° C, 25.2 g of oxalic acid anhydride and 612 g (10 moles) of 49% formaldehyde were introduced into a 6 liter reactor equipped with temperature and pressure regulator, mechanical stirrer, distillation column, separator and reflux tower. do. The temperature is linearly raised from 50 ° C. to 114 ° C. to reach reflux in about 30 minutes.

The mixture is heated in about 20 minutes and then dehydrated at a temperature below 180 ° C. to remove moisture under atmospheric pressure. The novolak is then vacuum heated to remove excess free phenol contained. The distillation of phenol never ends (eg, this process is carried out under vacuum produced by a water pump) and almost 1.5-5% of free phenol remains in the resin. Free phenol itself is easily measurable and also according to the present invention this problem is not important because the phenol itself can play a role in controlling the viscosity of the novolac phase, and for this reason, the amount of free phenol in the novolac It will be good to re-add up to 30% by weight.

Basic novolacs N ₁ , N ₂ and N ₃ having the properties shown in Table 2 were obtained by this method.

These novolac phases are produced as follows.

The above-mentioned novolak resin is heated to about 50 DEG C, made to be fluid, and then introduced into a vane equipped with a stirrer, a temperature probe, and a condenser, and a predetermined amount of an acid catalyst (sulfonic acid containing an aromatic nucleus) is added thereto. Next, if necessary, after the catalyst is heated, the foaming agent (or the mixture of the foaming agent according to the present invention) is slowly added while maintaining the temperature at 50 ° C or gradually decreasing the temperature. The mixture is stirred for several minutes.

The novolak phase shown in Table 3 was obtained by this method.

Example 3

[Manufacture of other jin novolak resins and various novolak phases]

4700 g (50 moles) of phenol at a temperature of 50 ° C. and 918 g (15 moles) of formaldehyde at 49% concentration are introduced into a 6 liter reactor equipped with a temperature and pressure regulator, a mechanical stirrer, a distillation column, a separator and a reflux column. To this mixture is added 25.2 g of oxalic acid dihydrate and heated to 60 ° C. The temperature is linearly raised in 30 minutes from 60 ° C to 114 ° C (reflux temperature).

After heating the mixture for about 20 minutes, the water is slowly removed under atmospheric pressure at a temperature of 180 캜 or lower. The novolak is heated in vacuo to remove excess phenol contained therein. The content of phenol present in the novolac phase can be finely adjusted in this way.

In this way, a jin novolak resin having the following properties can be obtained.

Phenolic content: about 2%

Average molecular weight: 265

By adding phenol to this jin novolak resin, novolak resins of various viscosities can be obtained. (Phenol is considered to be the simplest of the jin novolak resins) The novolak phase that can be used in the process of the present invention is prepared by adding 27.3 parts of phenolsulfonic acid and 19.1 parts of a foaming agent. The foaming agent is a mixture of 60% trichloroethane and 40% ethanol, and the remainder of the novolak phase (ie 53.6 parts) is a novolak resin. That is, examples of the mixture of jin novolak and phenol are shown in the following table.

Example 4

[Production of foam using substantially equal amount of resol and novolac phase]

Stable solutions (resol phase and novolac phase) are pumped and fed to the mixed tofu. The relative weight ratio of the two solutions is about 50/50. Mixing is performed at room temperature or slightly higher temperature and the residence time in the mixed tofu is less than 60 seconds. This mixture is sprayed into the vessel to initiate expansion. In this way, foam having a good structure (normal cell formation, cell size of about 0.1 to 1 mm) is obtained.

Example 5

These examples are summarized in Table IV.

In this example and each of the examples below, a foam is obtained by mixing different amounts, that is, 70% by weight of the resol phase and 30% by weight of the novolak phase.

70% by weight of the resol phase obtained in Example 1 was added to the mixer together with 30% by weight of the arbitrary and novolac phases (one of A, B, C, D, E and F) obtained in Example 3. The residence time in the mixer is 30 seconds. The initial temperature of these two phases is 23 ° C. The results are shown in Tables V to V. These relate to the foamability and the properties of the foams.

Table V shows the results for Resol phase R ₅ , Table VI for Resol phase R ₃ , Table VII resol phase R ₁ , and R ₂ , and Resol phase R ₂ and R ₃ containing a small amount of urea. will be.

In all these cases, the foam obtained has a regular cell structure and no shrinkage phenomenon.

Example 6

The method of Example 5 is repeated except that resol phase R ₆ is used instead of resol phase R ₅ . The foam obtained by the reaction between the resol phase R ₆ and the novolac phase D has a specific gravity of 70 kg / m ³ in the object.

Example 7

Les carried sol-like R ₅ instead of sol-like rail R and is carried out except for the use of ₁₀ Example 5 how a repeat of. Les sol-like R ₁₀ and a furnace for obtaining the foam by the reaction between the novolak D has an average density 50kg / m ^3, density of 21kg / m ³ from the object.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

TABLE 6

TABLE 7

TABLE 8

Claims (1)

Injecting the resol phase and the novolak phase into the mixer for about 5 to 90 seconds and then spraying the mixture product from the mixer to prepare a phenol-formaldehyde foam, the resol phase is homogeneous and has a viscosity of 8 to 8 ° C. 60 poise, and the resol contained in this resol phase is obtained by polycondensation of a mixture of phenol and formaldehyde having a molar ratio of 1: 1.5 to 1: 3 with a basic catalyst, the novolak phase being homogeneous and anhydrous at 20 ° C. Jin novolak resin obtained by cocondensing a mixture having an viscosity of about 5 to about 300 Poises and having a molar ratio of 10 to 35% by weight of the foaming agent and a molar ratio of phenol and formaldehyde of 2: 1 to 6: 1 with an acid catalyst. 70 to 90% by weight of the mixture consisting of 5 to 10% by weight of the free phenol relative to the mixture of the sol phase and the novolac phase, wherein the relative amounts of the resol phase and the novolac phase are in the range of 45 to 75 of the mixture. A process for producing a phenol-formaldehyde foam, characterized in that the amount of% by weight.