SI9200129A - Flexible phenol-formaldehyde resins and their application in the production of flexible foams - Google Patents

Abstract

Flexible phenol-aldehyde resin composition. It comprises, per 100 parts by weight of composition: - approximately from 65 to 80 parts by weight of a phenol-aldehyde of resole type, - approximately from 10 to 25 parts by weight of at least one glycol, and - approximately from 5 to 12 parts by weight of at least one oligomer or polymer with a glass transition temperature not exceeding approximately 40 DEG C, miscible with the phenol-aldehyde resin and with the glycol and containing at least one end-functional group capable of reacting with the phenol-aldehyde resin. Application to the production of flexible foams by mixing the said composition with at least one surface-active agent, at least one pore-forming agent and at least one acidic catalyst.

Description

Flexible phenol-formaldehyde resins and their use in the manufacture of flexible foams

The present invention relates to phenol-formaldehyde resins and foams having a flexible nature as well as to a process for their manufacture.

Phenol-formaldehyde is a synthetic resin that has been known for a long time and which, for many uses, has the significant downside of an almost complete lack of flexibility. This is especially reflected in the very small tear elongation and, in the case of foams obtained from such resins, in high brittleness. This latter nature is particularly evident in many uses, including those in mining. When high pressures occur, such as when moving floors or landslides, the phenol-formaldehyde resins used to harden corridors and tunnels in coal mines have poor resistance to stress and break or even break without absorbing shocks.

Therefore, in these applications there is a need to develop phenol-formaldehyde resins and foams that are flexible in nature, and this represents a problem to be solved by the present invention. Moreover, it is readily understood that many uses from which phenol-formaldehyde resins so far have been excluded in spite of their known other qualities, such as fire resistance, could be made available to them by providing them with some flexible nature.

Published Patent Application WO 86/07370 describes - in order to reduce the tendency of the resin to sag during burning and to increase its thermal conductivity without impairing its brittleness, its compressive strength and its low flammability - a process for the preparation of phenol-formaldehyde foam with sealed cells comprising (a) expulsion treatment of a resin-type phenol-aldehyde resin in the presence of a specified amount of a suitable solvent capable of altering its viscosity to a water content not exceeding 7 wt. % by resin, and to a suitable viscosity, preferably below 3.5 Pa.s, and then (b) an addition of 10 to 20% by weight, based on the resin of unbranched polyglycol dihydroxy ether having a molecular weight not exceeding 300. unfortunately, this process does not allow us to obtain phenol-formaldehyde foams that are flexible in nature.

In addition, it describes file EP-A-211,799 foundry sand binder comprising a strong alkane aqueous solution of phenol-formaldehyde resin that can be crosslinked with alkyl formate, from 2 to 10 wt.%, With respect to this solution, glycerol and where suitably, from 1 to 10% by weight, based on this solution, of polyethylene glycol having a molecular weight of between 200 and 600, provided that in this case the sum of glycerol and polyethylene glycol does not exceed 15% by weight of the resin solution.

This binder is embedded in a ratio of 1.4 parts per 100 parts sand.

In order to solve the problems described above, the present invention is based on the surprising discovery that a flexible nature can be achieved using a composition which combines a heat-curable phenol-aldehyde resin, at least one glycol, at least one oligomer or polymer having a low glass transition temperature , is miscible with the phenol-aldehyde resin and with glycol and contains an end-function capable of reacting with the phenolaldehyde resin and, where appropriate, at least one substance capable of binding the remaining aldehyde.

Specifically, the first object of the present invention relates to a resilient phenolaldehyde resin composition comprising, per 100 parts by weight of the composition:

from about 65 to 80 wt. parts of a phenol-aldehyde resin of resolvable type, from about 10 to 25 wt. parts of at least one glycol and from about 5 to 12 wt. parts of at least one oligomer or polymer having a glass transition temperature not exceeding about 40 ° C is miscible with the phenol-aldehyde resin and glycol and contains at least one end-function capable of reacting with the phenol-aldehyde resin.

The resin type resin present in the composition according to the invention is a known resin obtained preferably by condensation of an aldehyde, such as furfural or formaldehyde, and phenol in an aldehyde: phenol mole ratio of generally between about 0.8 and 1, 5, in a basic medium. In particular, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, their higher homologs and mixtures thereof in all ratios may be mentioned as a miscible oligomer or polymer. The numerical average of the molecular weights of these polyalkylene glycols is generally between about 150 and 1500 and preferably between about 700 and 1500.

As the glycol present in the composition according to the invention, in particular ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, their higher homologs and mixtures thereof in all ratios may be mentioned.

The resin composition of the invention may further comprise at least one substance capable of binding the remaining aldehyde, such as e.g. urea. Such a substance will generally be present in a proportion of up to about 3% by weight based on the sum of the other constituents of the composition.

The resin compositions according to the invention typically have a viscosity of between about 0.3 and 10.0 Pa.s at 20 ° C. Their dry extract content, determined according to ISO Standard 8618, is generally between about 65 and 85%. Their residual free aldehyde content is generally less than 1%.

The consequence of the condition of the miscibility of the oligomer or polymer having a low glass transition temperature with the other components of the resin composition according to the invention is that the resin can be prepared by blending it easily in any order of addition of its three main components, and where is suitably a substance for binding the remaining aldehyde.

The compositions of the invention have mechanical properties and, in particular, tear elongation, which greatly exceed the properties of known phenol-formaldehyde resins, i.e. those which do not contain glycol in combination with polyalkylene glycol. In particular, they are characterized by a ruptured elongation, determined in accordance with ISO Standard R 527, which is generally not less than about 20% and can reach as high as about 100%.

Another object of the present invention relates to the use of a resin composition as described above in the manufacture of a flexible phenol-aldehyde foam composition comprising a phenolaldehyde resin, at least one surfactant, at least one pore-forming agent, and at least one acid catalyst , characterized in that a composition comprising 100 wt.% is used as the phenolaldehyde resin. parts from about 65 to 90 wt. parts of phenyl aldehyde resin type resin, from about 5 to 25 wt. parts of at least one glycol and from about 3 to 12 wt. parts of at least one oligomer or polymer having a glass transition temperature not exceeding about 40 ° C, is miscible with the phenol-aldehyde resin and glycol and contains one end-function capable of reacting with the phenol-aldehyde resin.

In such a composition, flexible foams are preferably used per 100 parts by weight of 65 to 80% by weight. parts of resin-type resin, from 10 to 25 wt. parts of glycol and from 5 to 12 wt. parts of an oligomer or polymer having a glass transition temperature not exceeding 40 ° C.

The constituents of the specific phenol-aldehyde resin used in the flexible foam composition of the invention have been described in detail above. Other components of the flexible foam composition according to the invention are typical phenol-aldehyde foam components, and in particular:

An acid catalyst is generally a strong inorganic acid, such as sulfuric, hydrochloric, phosphoric or nitric acid or their concentrated aqueous solutions, or alternatively myoic organic acid, such as benzenesulfonic, toluenesulfonic, phenolsulfonic, para-toluenesulfonic, naphthylenesulfonic or naphthylenesulfonic or naphthylenesulfonic relationships.

The surfactant is generally a non-ionic agent, as a condensation product of alkylene oxides and, where appropriate, at least one compound selected from alkylphenols having from 8 to 12 carbon atoms in the alkyl group, fatty acids having at least 12 carbon atoms, and of alkylsiloxanes. Examples of such non-ionic agents include, in particular, block copolymers of ethylene oxide and propylene oxide, ethoxylated and, where appropriate, hydrogenated castor oil, and flax or castor and ethylene oxide condensation products. Surfactants having a hydrophobic fluorocarbon moiety may also be used.

The pore-forming agent is generally a liquid having a boiling point at atmospheric pressure of about -50 to + 100 ° C and preferably about 0 ° to 50 ° C. Preferred liquids are hydrocarbons and halogenated hydrocarbons such as n-pentane, cyclopentane, 2-methylbutane, trichlorofluoroethane, trichlorofluoromethane, trichlorotrifluoroethane CFC1 ₂ -CC1F ₂ and tetrafluorodichloroethane CF ₃ -CC1 ₂ F. Diethyl ether or ether is also used.

The flexible foam composition according to the invention of both generally per 100 parts by weight of phenolaldehyde resin:

from about 0.5 to 3 parts by weight of the surfactant, from about 0.5 to 15 parts by weight of the pore-forming agent, and from about 10 to 25 parts by weight of the acid catalyst.

The flexible foam composition of the Invention of the invention may comprise up to about 15 parts by weight of the host, such as wood flour or diatomaceous earth, per 100 parts by weight of phenol-aldehyde resin.

The flexible foam composition according to the invention can be obtained by first preparing a mixture of its four major constituents and then pouring the mixture into a mold and allowing it to crosslink. Generally, foam formation begins as soon as an acid catalyst is added. Times, temperatures and other reaction conditions are known to those skilled in the art.

In the case where the flexible foam composition according to the invention is intended to harden corridors and tunnels in coal and metal extractive mines, it is prepared in situ by injecting a mixture of its four main components into a tunnel or corridor.

The flexible foam compositions according to the invention exhibit a particularly advantageous behavior: in contrast to the known foams of the prior art in which the phenol-aldehyde resin is not associated with a combination of glycol and oligomer or polymer as defined above, they are capable of withstanding a pressure of more MPa without damaging their cellular structure and reaching their original volume again after a certain period of time. This behavior differs from that of conventional phenol-formaldehyde resins, which crushes when destroyed by their cellular structure.

In addition, the flexible foam composition according to the invention has the ability to age well. Unlike conventional phenol-formaldehyde foams, whose brittleness and compressive strength increase significantly over time, the flexibility of the foams according to the invention does not change significantly with time.

In view of these different qualities, flexible foam compositions according to the invention are advantageously used in supporting mine corridors by injection molding, as well as in the curing of rocks in public works - especially tunnels - and as a blockage material in the packaging industry.

The examples below are intended to illustrate the invention and are not intended to be limiting in any way.

EXAMPLE 1

2425 g of phenol, 774 g of formaldehyde in 50% aqueous solution and 10.3 g of sodium hydroxide in 50% aqueous solution were placed at 50 ° C in a reactor equipped with a mechanical stirrer and reflux condenser. The temperature was raised to 100 ° C and the metabolism was performed for 60 minutes. The temperature was then lowered to 50 [deg.] C. and the solution neutralized with 0.25 mol of lactic acid and concentrated in vacuo to a viscosity of 18.0 Pa.s. The resulting resolution was added to 413 g of polypropylene glycol with a number average molecular weight of 1000, 67 g of urea and 900 g of diethylene glycol. Thus, a phenol-formaldehyde resin composition capable of crosslinking is obtained which has a flexible nature, which will be demonstrated in the examples below.

EXAMPLE 2

From the flexible phenol-formaldehyde resin obtained in Example 1, foam is prepared by pouring at 20 ° C into an open mold a composition comprising

100 wt. parts of the resin of Example 1, wt. part of a non-ionic emulsifier consisting of a condensate of ethylene oxide and linseed oil sold under the name CEMULSOL B, parts by weight of a catalyst sold by CRAY VALLEY SA under the name C 2965 and comprising a mixture of 27.8% by weight 65 wt% para-toluenesulfonic acid, 64.8 wt% 70% phenolsulfonic acid, 3.7 wt% resorcinol and 3.7 wt% water, wt. parts of a pore-forming agent consisting of trichlorotrifluoroethane CFC1 ₂ -CC1F ₂ commercially available under the name FORANE 113.

The foam formation, which is an exothermic reaction, is completed after 20 minutes and the product is then allowed to cool to room temperature. On the foam thus obtained, a compressive strength test according to ISO Standard 844 is carried out in which changes in the compressive load (expressed in kPa) are recorded as a function of the compression ratio e (expressed in%). These changes are reflected in curve A in the attached figure. The foam sample on which we performed the test regains its initial volume within minutes.

EXAMPLE 3 (Comparative)

The method of operation of Example 1 is repeated to prepare the resin from

- 2425 g of phenol,

-1161 g formaldehyde,

- 80 g urea and

- 319 g ethylene glycol.

From this resin, the foam is prepared according to the method of operation of Example 2. The resulting foam is then subjected to a compressive test according to ISO Standard 844, and the results of this test are shown as curve B in the accompanying figure. This curve is characteristic of the behavior of the crushing foam, with each tip corresponding to the strength of one layer of cells, followed by the collapse of that layer. Of course, we don't get the original volume again.

EXAMPLE 4

The phenol-formaldehyde resin (100 parts by weight) prepared in Example 1 was mixed with a crosslinking catalyst (5 parts by weight) consisting of a mixture

- 81,5 wt. % 65% para-toluenesulfonic acid,

-11,7 wt. % water and

- 6,8 wt. % 75% phosphoric acid.

Such catalyzed resin is exposed for 1.5 hours to the first curing at 50 ° C and then to the subsequent curing for 17 hours at 80 ° C.

The burst deformation rate measured on this crosslinked resin according to ISO Standard R 527 is 84%.

EXAMPLE 5 (Comparative)

The phenol-formaldehyde resin prepared in Example 3 is catalyzed and crosslinked according to the mode of operation of Example 4. The burst deformation rate measured on this crosslinked resin according to ISO Standard R 527 is 2%.

EXAMPLE 6

From the flexible phenol-formaldehyde resin of Example 1, a foam composition was prepared at 20 ° C comprising

-100 parts by weight of resin,

-1.4 wt. part of the pore-forming agent, FORANE 113,

-1 wt. part of the non-ionic emulsifier CEMULSOL B and - 20,5 wt. of catalyst part C 2965.

After 20 minutes, the foam formation is complete and the mixture is allowed to cool. The foam obtained with a density of 0.25 g / cm ³ is characterized by the following values in the compressive test according to ISO Standard 844:

load at 10% compression: 86 kPa load at 90% compression: 33000 kPa

The sample used to make the measurements regains its initial volume within minutes.

EXAMPLE 7

Repeat the method of Example 1, only to replace the polypropylene glycol with an identical amount of polyethylene glycol. Foam obtained from the resin obtained in such a flexible manner as the resin of Example 1 is prepared according to the method of operation of Example 6. The foam obtained, having a density of 0.28 g / cm ^3, is characterized by the following values in the compressive test according to ISO Standard 844:

load at 10% compression: 5.6 kPa load at 90% compression: 7000 kPa

The sample on which the measurement was made regains its initial volume within minutes.

EXAMPLE 8

2425 g of phenol, 774 g of formaldehyde in 50% aqueous solution and 10.3 g of sodium hydroxide in 50% aqueous solution were placed in a reactor equipped with a mechanical stirrer and reflux condenser. The temperature was raised to 100 ° C and metabolized for 45 minutes. The temperature was then lowered to 50 ° C and the solution was neutralized with 0.25 mol of lactic acid and concentrated in vacuo to a viscosity of 5.0 Pa.s. The resulting resolution was added to 413 g of polypropylene glycol with a number average molecular weight of 1000, 67 g of urea and 900 g of diethylene glycol.

From the resin thus obtained, a composition of phenol-formaldehyde foam comprising at 20 ° C is prepared.

-100 parts by weight of phenol-formaldehyde resin,

- 1,4 wt. part of the pore-forming agent, FORANE 113,

- 1 wt. part of the CEMULSOL B nonionic emulsifier and

- 15,4 wt. catalyst part C 2965.

The foam obtained with a density of 0.18 g / cm ³ is characterized by the following values in the compressive test according to ISO Standard 844:

- load at 10% compression: 20,2 kPa

- 90% compression load: 2000 kPa.

The sample on which the measurement was performed regains its initial volume within a few minutes.

Claims (10)

A resilient phenol-aldehyde resin composition, characterized in that it comprises, per 100 parts by weight of the composition, from 65 to 80 parts by weight of the phenol-aldehyde resin of the resolvable type, from 10 to 25 parts by weight of glycol and from 5 to 12% by weight. parts of at least one oligomer or polymer having a glass transition temperature not exceeding 40 ° C, is miscible with the phenol-aldehyde resin and glycol and contains at least one end-function capable of reacting with the phenol-aldehyde resin. A resin composition according to claim 1, characterized in that the oligomer or polymer having a glass transition temperature not exceeding 40 ° C is polyalkylene glycol. Resin composition according to any one of claims 1 and 2, characterized in that the oligomer or polymer having a glass transition temperature not exceeding 40 ° C is polyalkylene glycol with an average molecular weight between 150 and 1500. Resin composition according to one of claims 1 to 3, characterized in that it further comprises at least one substance capable of binding the remaining aldehyde. A resin composition according to claim 4, characterized in that this substance is present in an amount up to 3% by weight based on the sum of the other constituents of the composition. A resin composition according to any one of claims 1 to 5, characterized in that its viscosity at 20 ° C is between 0.3 and 10.0 Pa.s. Resin composition according to one of Claims 1 to 6, characterized in that its tear strength according to ISO Standard R 527 is between 20% and 100%. 8. A resilient phenol-aldehyde foam composition comprising a phenol-aldehyde resin, at least one surfactant, at least one pore-forming agent, and at least one acid catalyst, characterized in that a composition is used as the phenol-aldehyde resin. comprising, per 100 parts by weight, from 65 to 90 parts by weight of the phenol-aldehyde resin type resin type, from 5 to 25 parts by weight of at least one glycol, from 3 to 12 parts by weight of at least one oligomer or polymer having a glass transition temperature, Not exceeding 40 ° C, it is miscible with the phenol-aldehyde resin and with glycol and contains at least one end-function capable of reacting with the phenol-aldehyde resin. A resilient phenol-aldehyde foam composition according to claim 8, characterized in that it comprises 100 parts by weight of phenol-aldehyde resin - from 0.5 to 3 parts by weight of surfactant, from 0,5 to 15 parts by weight of the pore - forming agent, and - from 10 to 25 parts by weight of acid catalyst. A resilient phenol-aldehyde foam composition according to any one of claims 8 and 9, characterized in that it further comprises up to 15 parts by weight of a host per 100 parts by weight of the phenol-aldehyde resin.