HU193262B - Process for preparing plastic foam - Google Patents

Abstract

The present invention is a phenolic formaldehyde of resin type by mixing resin, propellant and acid catalyst can be produced from foams that can be produced in such a way that the plastic foam is mechanical strength and structure to improve the initial mixture 2-4% orthoboric acid dissolved in phenol alcohols phenol-formaldehyde • 10% to 50% by weight of resin quantities.

Description

FIELD OF THE INVENTION The present invention relates to a process for the production of phenolic formaldehyde-based resole-type plastic foams which are useful as heat insulating materials in the architectural, conveyor, refrigeration and other applications.

It is known to produce a phenolic formaldehyde-based resole-type resin foam by mixing the resin mixture with a propellant with an acid catalyst and, if desired, other additives, and then foaming and curing the resulting mixture at room temperature or moderately elevated temperature. No. 2,728,702 SU patent specification.

The process, as well as certain characteristics of the finished plastic foam, can be influenced, within certain limits, by the type and amount of blend components to be foamed.

A disadvantage of the process is that in the case of resole concentrates, which are mixtures of cast resins and which exhibit different activities in foaming and curing, a uniformly distributed porous structure cannot be achieved.

In another known process, resole-type phenol-formaldehyde resins are also blended with a propellant and an acidic catalyst, and the resulting mixture is foamed and cured, but the resulting plastic foam has insufficient mechanical strength and porous structure, thus limiting its usefulness. copyright certificate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for producing plastic foam of greater strength and more uniformly distributed in the powder.

The above object can be achieved by a process which comprises mixing a phenol-formaldehyde resin of the resole type with a propellant and an acidic catalyst, and then, before foaming and curing, the resulting mixture is mixed with a 2-4% solution of orthoboric acid in phenol alcohol. added. 10 to 50% by weight, based on the amount of phenol-formaldehyde resin. The phenolic alcohol is prepared from 1 mol of phenol and 0.7 to 1.5 mol of formaldehyde in the presence of a catalytic amount of alkali.

In the process of the invention, the phenolic alcohol solution of orthoboric acid is preferably added to the resole-type resin step, which simplifies the production of the plastic foam by decreasing the viscosity of the blend, increasing stability and reducing the number of components of the blend.

In the process according to the invention, 100 parts by weight of a liquid resole-type phenol-formaldehyde resin are added with 10-50% by weight of a solution of 2-4% orthoboric acid-phenol alcohol, with the necessary amount of acidic catalyst (strong mineral acids such as hydrochloric sulfoaromatic acids or their 2 oligomeric condensation products), the blowing agent (finely dispersed aluminum powder, boiling point chlorofluorocarbons up to 80 ° C), surfactants (e.g. ethylene oxide products of mono- or dialkyl phenols) and optionally other additives, such as fillers, dyes, modifiers, etc., are mixed and the mixture is formulated or applied directly at the application site at ambient pressure and ambient temperature, possibly at elevated temperature / max. 100 ° C / foam and cure. The components may be mixed continuously or batchwise, in-house or directly at the point of use.

Addition of a phenolic alcohol solution of orthoboric acid in an amount of less than 10% or greater than 50% is not advisable, since in the first case the effect is unsatisfactory and in the second case the same result is obtained with less efficiency.

The phenolic alcohol solution of orthoboric acid is preferably added during the preparation of the resole type to be foamed, so that it is possible to neutralize the alkali catalysts used in the preparation and to mix the additive of the invention with the resin. The resultant mixture has a pH of 4.5-7.0, preferably 5.5-6.5, stability during storage and transport, which results in a more uniform quality and easier processing on site.

A very significant advantage of the process according to the invention is that it can also foam high-condensation phenol-formaldehyde resins which, due to their high viscosity, have not been suitable for the production of high quality foams according to the prior art.

Example 1 Reaction of a mole of phenol with 2 moles of formaldehyde in an alkaline medium to obtain a resole resin having a viscosity of 1000 cP and addition of 50% by weight of a 3% solution of orthoboric acid in phenol alcohol containing 1 mole of phenol and 0.7 mole of formaldehyde a primary reaction product formed in the presence of a catalytic amount of alkali. The pH was then lowered from 9.2 to 5.5 by addition of an acid solution and the resin so neutralized was dried in vacuo to give a viscosity of 7000 cP.

To produce the foam, 100 parts by weight of the above resol resin are treated with 3 parts by weight of mono- or dialkyl phenol ethylene oxide, 2 parts by weight of aluminum powder and 20 parts by weight of phenol urea-formaldehyde, previously added with orthophosphoric acid. The resulting mixture was foamed at room temperature and cured. The resulting foam has an apparent density of 72 kg / m ³ and a compressive strength of G _{n /} = 49 x ^{10 4} Pa.

Prepared from a mixture of the same compositions and under similar conditions but without addition of a phenolic alcohol solution of orthoboric acid

At room temperature -2193262 no foam could be produced.

Example 2

The composition of the mixture to be baked is as follows:

-resol-phenol-formaldehyde resin having a viscosity of 50 mPa.s x 100 parts by weight

-4% solution of orthoboric acid in phenol alcohol, made from 1 mol of phenol and

1.5 moles of formaldehyde alkali 10 obtained in primary medium by re- action products 10 parts —Polyether based on propylene oxide ethylene -1,1,2-trichloro-1,2,3-trifluoro- 0.5 parts 15 -ethane / Freon-113 / -acid catalyst / phenol- 7 parts —Sulfocarbamide-formaldehyde condensation. product 20 parts 20

The materials of the above composition are mixed and foamed and cured in the form without external preheating. The resulting foam has an apparent density 57 kg / m ^3, nyomósziiárdsá- 25g G _{"í /} = 40,18xl0 ⁴ Pa.

Example 3

A block of foam material is prepared in a 0.8 x 0.5 x 0.01 m metal form from a mixture of 100 parts by weight of phenol-formaldehyde resin / viscosity in the condensation step of 100 mPa.s, 30 parts by weight of 2% ortho-boron. Reaction product of v-phenol alcohol, 3 parts by weight of mono or dialkyl phenol and ethylene oxide. Reaction product of 1 part by weight aluminum powder and 15 parts by weight of phenolsulfone carbide and formaldehyde, to which is added orthophosphoric acid. The resulting foam material had an apparent average density of 79 kg / m ³ and a compressive strength of G _{7 -} 49.0 x 10 ⁴ Pa.

Example 4.

For the purpose of comparison, a plastic foam is prepared according to a known method. No. 233,898 SU copyright certificate).

The foam was prepared by condensing 100 parts by weight of phenol-formaldehyde resin, prepared by condensing 1 molar phenol and 1.65 mol formaldehyde with water in a 1:10 ratio to caustic soda, to pH 7.0 with acid, and the resulting material was dried in vacuo (1 part by weight of aluminum powder, 3 parts by weight of the reaction product of mono- or dialkylphenol and ethylene oxide) to which orthophosphoric acid was added.

Foaming and curing in a 0.8 x 0.6 x xOJ m metal form at room temperature / approx. 20 ° C. The resulting foam has an apparent density of 75 kg / m ^3, compression strength G ',, = 20,58xl0 ⁴ Pa.

The following table summarizes the characteristics of the plastic foams prepared according to Examples 1-4.

Table I

Example number Copper foam resole · Copper Characteristics of the phenol-formaldehyde plastic foam produced apparent density in kg / m ³ compressive strength kp / cm ² pore structure on cut surface visually 1 2 3 4 5 1. Phenol and one mole of product and a viscosity was 2 moles of alkaline formaldehyde condensation 1000 mPa.s which crosslinking eló'tt 3 ^ 50% aqueous orthophosphoric acid _(Η? Β0 ₃₎ fenolalkoholos is added, the final mixture has a viscosity of 7000 mPa.s, pH 5.5 72 5.0 steady microporous structure bigger cat vernas and we vessels without 2, Resole-phenol-formaldehyde resin, viscosity in condensation step 50 mPaxs 10% by weight mixed with 3% orthoboric acid in phenol alcohol solution 57 4.1 _11 _

-3I93262

Table I (continued)

1 She 3 4 5 Third Rezol-phenol-formaldehyde resin mixed with 3.0 weight% Z 2Z orthoboric acid-phenol in alcohol before foaming 79 5.0 4th Rezol-phenol-formaldehyde resin without phenol-alcoholic solution of orthoboric acid (known procedure) 75 2.0 Smooth powder structure with many large airbags

As can be seen from the table above, the mechanical strength of the foams produced by the process according to the invention and the higher quality porous structure significantly exceed the similar properties of the foam produced by the known process.

In addition, the process according to the invention has the following advantages: - it is possible to produce high-viscosity, high-condensation resole resins in a simple manner, - it is possible to balance the rate of foaming and curing, which ensures a uniform pore structure,

- allows to minimize the number of starting components and to foam at the place of use despite the use of the additive.

The process of the invention without any bi Q ₂ hereinafter used in the industry, because no additional investments or new, requires no special materials.

Claims (2)

PATENT CLAIMS A process for the production of plastic foams by mixing phenol-formaldehyde resins of the zeolite type, a propellant, an acidic catalyst, and subsequently foaming and curing the mixture, characterized in that the phenol-formaldehyde 10 to 50% by weight of a 2 to 4% solution of orthoboric acid-phenol in alcohol is added per 30 resins. The method of claim 1, wherein: This was done by mixing the phenol-formaldehyde resin with a 2-4% solution of orthoboric acid in phenol alcohol.