FI57437C - FRAMEWORK FOR THE SUSPENSION OF SUSPENSION - Google Patents

Description

[vSr ^ l Μ (11) MONTHLY PUBLICATION 574 37 JMä lj ν} UTLÄGGN I NGSSKRIFT 3 1 H ° '5¾¾ C (4S) r ^ ur.tti 11 -1 ^ (51) Kv.lk.3 / lm. a3 C 08 J 9/14 ENGLISH —EN N LAN D (21) Pwunttlhukumu · - PatmcaraMmifig 1033/72 (22) Hakmnlspeivl — AiMBknlngid «f 12.0U.72 (23) AlkupUvt — Glltighuttdag 12.0U.72 (41) Tullut JulklMksI - Blhrft offmtllg l6.10.72

National Board of Patents and Registration (44) NihUviluip ^ j. Date of issue

Patent- och reglsterstyrelsen ’Amöki» utkgd «eh utUknfUn pubUcmd 30.0U. 80 (32) (33) (31) Requested «uollnus — Begird prlorltet 15.0U. 71

France-Frankrike (FR) 7113238 (71) Saint-Gobain, 62 Bd Victor Hugo, 92 Neuilly sur Seine, France-Frankrike (FR) (72) Daniel Hanton, Estrees-Saint-Denis, France-Frankrike (FR) (7U) Berggren Oy Ab (5U) The present invention relates to a process for the preparation of phenolic resin foam from a phenol-formaldehyde mixture which is condensed with a base. The resulting resole is mixed with a blowing agent, a cell formation regulating agent and an acid to give a cellular product.

The invention seeks to produce a phenolic resin foam, the majority of the cells of which are closed and self-extinguishing, the latter property being obtained without the use of flame retardants.

Phenol resoles commonly used in the manufacture of foams fall into two groups: those obtained by condensation in an alkaline medium and under the influence of heat in aqueous formaldehyde with phenol, with an initial molar ratio of the two reactants of 1.7 or more; these are referred to as Resolutions I, and those obtained by the same method but having an initial molar ratio of less than 1.7 as mentioned above are referred to as Resolutions II.

It is also known to prepare resole resins in two steps by condensing in a first step in an acidic medium to give a novolak resin, which is then condensed in a second step in an alkaline medium by adding excess formaldehyde. These resole resins are not suitable for making cheap self-extinguishing phenolic resin foams.

It is further known to prepare a phenolic resin foam starting from a phenolic compound mixture comprising a polycyclic diphenol. However, these phenolic resin foams are clearly different from foams made from resoles II.

In order to obtain a cellular product, it is always necessary to pre-concentrate the aqueous solutions or dispersions of the resols obtained by condensing formaldehyde with phenol using appropriate physical methods to remove excess water.

The flotation and curing of these resoles can be carried out by introducing a catalyst and in particular a concentrated acid such as hydrochloric acid in the presence of a blowing agent which may decompose by heat releasing a large amount of gas or a low boiling liquid such as pentane. in the presence of a surfactant such as water-soluble silicone oils.

After curing, the foams are dried with hot air to remove water and most of the hydrochloric acid they contain.

In general, the foams finally obtained have a large number of open cells, which is why they are very easily permeable to gases and vapors and are very brittle, which occurs especially when the density of the foams is low.

When fully dried foams obtained from resoles I are subjected to the ASTM D 635-68 fire resistance test, i.e. when subjected to a flame until the temperature in the small test zone exceeds 250 ° C and then the flame effect is then stopped, the resulting combustion spreads throughout the test piece. rise to 800 ° C, whereby the substance is completely charred.

In order to obtain foams which do not spread and do not continue to burn after the action of the flame, it is known to mix these additives, before their expansion, with various additives, such as nitrogen compounds such as urea, dicyandiamide, melamine or their derivatives.

In contrast, foams made from resoles II, which have also been completely dried, are automatically extinguished in a similar ASTM D 635-68 3 57437 test when the effect of the flame has ceased, without the need to add extinguishing agents.

In addition, the production of foams from resoles I is difficult because these resoles are rather slow-reacting and require a large amount of a highly reactive catalyst, such as a concentrated acid such as hydrochloric acid, and very often above 80 ° C to accelerate resin reticulation at the end of the expansion step.

In the production on an industrial scale, cell masses must be heated for a long time in order to remove as completely as possible the acid used as catalyst, or subjected to alkaline substances such as ammonia gas in order to neutralize said acid.

In the production of foams from resoles II, which in turn are obtained by the above method, the difficulties are quite different. These resoles II are very reactive, but the reaction causing the resin to swell and cure only begins when a minimum amount of concentrated acid, such as hydrochloric acid, is added, the reaction is then very rapid and very exothermic, i.e. difficult to control.

For this reason, the cells of the resins obtained are irregular in size, their walls are brittle and most of them are open, which of course means that the product obtained is brittle and permeable to gases and vapors.

It has now been found that the behavior of resoles II when adding hydrochloric acid was due to the large amount of phenol free in the reaction mixture. Namely, the addition of pure phenol to said mixture increases the exotherm of the reaction, which is directly dependent on the amount of phenol added.

The amount of phenol free in the resoles II can be reduced by increasing the condensation time of the phenol and formaldehyde in the reactor or by raising the temperature of the mixture of the two reactants.

However, the resoles II thus obtained are unfortunately slow-reacting and cannot be made into non-dense foams.

It has now been found that resoles II bis can be prepared which in turn allow the production of light, closed cell foams by modifying the condensation process of phenol and formaldehyde by passing formaldehyde and a basic catalyst in two or more successive steps than the final amount of phenol until %.

“57437

The invention thus relates to a process for the preparation of self-extinguishing phenolic resin foams with predominantly closed cells, first preparing an alkali-catalyzed resole with a molar ratio of formaldehyde / phenol of less than 1.7 »and then foaming a mixture containing resole, swelling agent, cell control agent and acid, and the process according to the invention is characterized in that formaldehyde and catalyst are added to the amount of phenol in at least two steps during the preparation of resole, the reaction mixture is neutralized and concentrated to a dry matter content of 66-80%, the free phenol content being less than 8% of the concentrated mixture, after which the flotation is carried out in a manner known per se.

The use of resoles II bis with a lower amount of free phenol causes a decrease in the exotherm of the reaction and consequently slows down the expansion and curing of the resin during the flotation step, creating a balance between the expansion gas pressure and the thickening and curing of the resulting gas-containing solid. For this reason, the initially formed closed cells remain intact until the end of the flotation and curing step.

This gives phenolic foams whose cells are closed, evenly distributed and self-extinguishing.

According to one embodiment of the invention, in the first step the whole amount of phenol, part of the formaldehyde and part of the basic catalyst is derived and in the second step a second part of the formaldehyde and the basic catalyst is added.

The condensation steps of the resole can be performed continuously.

According to the invention, the amount of free phenol contained in the condensed resole may preferably be 6-8% of the total weight of the resulting resole after concentration, and the molar ratio of formaldehyde to phenol may preferably be 1.0-1.6.

The resole condensation catalyst is preferably a base such as sodium hydroxide, barium hydroxide or potassium hydroxide. When using sodium hydroxide, which, as mentioned above, is preferably added to the resole in at least two steps, 0.5-2% of the total weight of phenol is used in each addition step.

The condensation temperature of the first stage may be 70-100 ° C and the condensation time which is shorter the higher the temperature 1 may be 1 / 2-3 hours. The condensation temperature of the later stages is preferably lower than the condensation temperature of the first stage with the condensation time moving within the same limits.

After condensation, the resin is neutralized and then maintained at ambient temperature. Upon cooling, the resin decantes. The decanted phase is then concentrated in vacuo or mechanically centrifuged to remove excess water.

After concentration, the properties of this resin are usually as follows:

Dry extraction 66-80% and preferably 70-75% ·

The amount of free formaldehyde after concentration of the resole is 0.2-1.5%> and preferably 0.4-0.8% of the total weight.

- The amount of free phenol is less than 8% of the total mass after concentration of the resole.

Viscosity at 20 ° C 5-100 poise and preferably 40-80 poise.

6 57437 - the pH is preferably 7-7.5 ·

The following are examples of resin preparation methods according to the invention.

Preparation of Resole A A 4 liter reaction vessel is charged with vigorous stirring to 13 moles of phenol and 21.6 moles of formaldehyde in a 35.5 S »aqueous solution. When the temperature of the reaction vessel has risen to 70 ° C, 16.9 g of NaOH are gradually added.

The temperature rises to 100 ° C and this temperature is maintained for 1 hour, cooled to 70 ° C and 3.6 moles of similar formaldehyde are added. The temperature is raised to 80 ° C and 8.5 g of NaOK are added. This temperature is maintained for 1 hour.

At the end of this time, the sodium hydroxide is cooled and neutralized with 40 ml of 35 ml of hydrochloric acid. The final pH is 7.3 ·

The resole is decanted and a smaller resin phase of about 75% of the total volume is recovered.

The dry extract of this resole is 66%.

The resole is then concentrated in vacuo at a maximum temperature of 30 ° C. After concentration, a clear solution of resole A is obtained, the properties of which are shown in Table I below.

Preparation of resin B.

According to the preparation of Resole A, 18 moles of phenol and 21.6 moles of formaldehyde are introduced into a 4-liter reaction vessel. When the temperature has risen to 70 ° C, 16.9 g of NaOH are introduced. The temperature is raised to 100 ° C and maintained at this value for 1 hour. Cool to 80 ° C and add 3.6 moles of formaldehyde. The temperature is raised to 90 ° C and 8.5 g of NaOH are added. The temperature is maintained at this value for 1/2 hour. The procedure is then the same as for the production of resol A.

After concentration, a clear solution of resolution B is obtained.

Preparation of resin C.

According to the preparation of Resole A · 72 moles of phenol and 86.4 moles of formaldehyde are introduced into a 20 liter reaction vessel as a 35.5% aqueous solution; when the temperature is raised to 70 ° C, 67.6 g of NaOH are gradually added. The temperature is raised to 101 ° C and maintained for 45 minutes. It is then cooled to 80 [deg.] C. and 14.4 mol of formaldehyde and then 67.6 g of NaOH are added. The temperature is kept at the same value for another hour. Cool and neutralize with 36 ml of 18% hydrochloric acid. After decantation, the resole-containing layer is separated and concentrated in vacuo to 7,57437. A clear solution of resole C is obtained.

Table I

Resoli A. B C

Dry extract 72% 74% 70.5%

Viscosity at 20 ° C 45 poise 82 poise 10.5 poise

Free formaldehyde 0.75% 0.24% 1.3%

Free phenol 7 »25% 7.56% 1.1%

Percentages refer to percentages in question. of the total mass of the solution.

The following products are used to foam resole: - A blowing agent selected from resole-soluble or insoluble low-boiling liquids. Of these, aliphatic hydrocarbons such as butane, pentane, hexane and their isomers, halogenated hydrocarbons such as trichloromonofluoromethane, methylene chloride, trichlorotrifluoromethane, etc. can be used, but are not limited to the invention.

- A surfactant that regulates cell structure. This product can be selected from water-soluble and insoluble oxyalkylene-silicone copolymer compounds.

- A reticulation catalyst, preferably chloroformic acid in a 36% aqueous solution with a density of 1.18 to 1.19 ·

The following are examples of the foams of the above resols.

Example 1 To 100 g of resolution A is added 1.5 S of water-soluble silicone oil (e.g. Union Carbiden L 5320), 5 g of technical grade pentane, and then finally 5 g of 36% hydrochloric acid. After vigorous mixing, the paste is drained into a mold preheated to 55 ° C. After 8 minutes, the resin foam with a very fine cellular structure is removed from the mold.

After drying with hot air at 100 ° C, a cellular product with a density of 3b kg / m 2 is obtained.

This foam, which has 95% closed cells, is not brittle and has a compressive strength of 2.2 kg / cm 2 with 5% flattening (NF T 56.101).

2

The water vapor permeability is 0.054 g / m / h at a thickness of 1 m (NF T 56.105).

This foam is self-extinguishing in the ASTM D 635-60 test.

8 57437

Example 2 10 g of silicone oil (e.g. Dow Corning oil MDC 190 ”), 30 g of technical grade pentane and finally 25 g of 36% hydrochloric acid are added. The paste obtained after vigorous mixing is drained into a parallelepiped mold heated to 60 ° C in advance. After 7 minutes, a fine and uniform foam with a density of 28 kg / m 2 is obtained after drying.

This foam is not brittle. The number of closed cells is 55%.

The compressive strength according to NF T 56.101 is 5% 'with a flattening of 1.4 kg / cm2.

The thermal conductivity at 23.9 ° C is 0.029 kcal / m / t / ° C.

In the ASTM D 635-68 test, the foam self-extinguishes.

Example 3 5 g of silicone oil (e.g. Union Carbiden L 5340), then 30 g of technical grade pentane and finally 25 g of 26% hydrochloric acid are added. After vigorous mixing, a homogeneous flowable paste is obtained, which is poured into a pre-heated mold at 55 ° C. After 8-10 minutes, a fine and regular foam similar to that obtained in Example 2 is obtained.

Example 4

The procedure is the same as in Example 1, but instead of a batch of 30 g of technical grade pentane, 70 g of monofluorotrichloromethane are used.

In order to illustrate the differences between the resoles II used so far and the resis II bis prepared according to the invention, both resoles have been prepared using the same equipment, the properties of which are shown in the following Table II:

Table II

Resolution type_Unit_II bis_II

Mole of phenol 1 1 1. vai-ι Mole of formaldehyde (35% aqueous solution) 1.2 1.4

NaOH (% by weight of phenol)% 1 1

Condensation temperature ° C 100 90

Condensation time min. 60 45

Formaldehyde ($ 35 aqueous solution) mole 0.2 2nd step- NaOH (% of phenol mass)% 1 - he Condensation temperature ° C 80

Condensation time min. 60

The molar ratio of total formaldehyde to lfit 1,4 phenol was 9,57437

Resolution type_ Unit_II bis II

Vacuum Dry Extract% 72 74.5 Centro- Viscosity at 20 ° C 100 poise 4500 3500 dun re- Free formaldehyde% 0.75 1.65 so. Free phenol% 7.25 11.2 properties

Percentages refer to percentages in question. of the total mass of the reaction solution after concentration.

The properties of foams made from resoles II bis and II are summarized in Table III.

Table III

Composition Example 1 Example 2

Resole II bis 100 g

Resole II - 100 g

Silicone oil (Union Carbide L 5320) 2 g 2 g pentane 5 g 5 g 35% hydrochloric acid 5 g 5 g curing time 8 min. 2 min.

flotation temperature 55 ° C 20 ° C

Properties of the obtained foams:

Density 36 kg / cm · ^ 18 kg / m · ^ cell size <1 mm 3-4 mm number of closed cells 95% zero brittleness not brittle very brittle compressive strength (5% by flattening NF T 56101) 2.2 kg / cm2 <2 .0 kg / cm2 reaction to fire flame does not spread, (ASTM F 635-68 standard) self-extinguishing This table clearly shows that the foam prepared with the same composition from Resolution II according to Example 2 swells more and faster than the foam from Condensation II condensed in two steps according to the invention. bis made. Therefore, the foam of Example 2 is not as dense, but the cells are open and much larger in size.

The foam of Example 2 has a lower mechanical strength than the foam of Example 1 and is much more brittle.

The advantages of the resoles and foams produced by the process according to the invention are in particular the following: 57437 10 - A simple composition of a foam compound; - Expansion and curing of the foam are easily controlled; - A self-extinguishing foam is obtained without the addition of flame retardants; - The number of closed cells in the foam is very high, which is why it is not fragile even in the least dense and has poor permeability to gases and vapors; - Possibility to produce low density (20-50 kg / m ^) products with good mechanical properties without special difficulties; - Expansion and curing are achieved by the addition of a small amount of catalyst (volatile acid), which facilitates the subsequent drying of the product.

Thanks to these advantages, foams can be produced at very low cost.

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Claims (7)

11 57437 A process for preparing self-extinguishing phenolic resin foams having predominantly closed cells, first preparing an alkali-catalyzed resole with a molar ratio of formaldehyde / phenol of less than 1.7, and then foaming a mixture containing resole, a blowing agent, a cell control agent and an acid, characterized in that that formaldehyde and catalyst are added to the total amount of phenol in at least two steps during the preparation of resole, the reaction mixture is neutralized and concentrated to a dry matter content of 66-80%, the free phenol content being less than 8% of the concentrated mixture, followed by flotation in a manner known per se. Process according to Claim 1, characterized in that the resole is prepared in two steps, the first step adding all the phenol, part of the formaldehyde and part of the alkali catalyst, and in the second step adding the rest of the formaldehyde and the alkali catalyst. Process according to Claims 1 and 2, characterized in that the amount of free phenol in the concentrated resole is 6-8%. Process according to Claims 1 to 3, characterized in that the molar ratio of formaldehyde to phenol is 1.0 to 1.6. Process according to Claims 1 to 4, characterized in that the amount of free formaldehyde in the resole is 0.4 to 0.8% of the concentrated reaction mixture. Method according to Claims 1 to 5, characterized in that the temperature of the condensation step following the first condensation step is lower than the temperature of the first step. 1. A process for the production of phenolic resins and cellulose-containing chlorolymers having the characteristic alkali catalyst and a solution of molybdenum and phenol having a formaldehyde / phenol content of less than 1,7, and the presence of an explosive mixture, in the form of a solution of the resin form and the catalyst in the form of a solid phenol game, the reaction mixture is neutralized and concentrated to a maximum of 66-80% of the color of the phenol