CH662577A5 - FOAMABLE COMPOSITION COMPRISING A PHENOLFORMALDEHYDRESOL. - Google Patents

Description

The invention relates to a foamable composition comprising phenol formaldehyde resoles, which comprises at least one aqueous phenol formaldehyde resole, a surface-active agent, a foaming agent and an acid catalyst, to a use for producing phenolic foams from such compositions and to the foams produced in this way.

Phenolic foams made from phenolic resoles have been known for years. It is generally believed that phenolic foams have the best fire values of any known foam insulation. A phenolic foam does not burn, even if it is brought into contact with the flame of a welding torch, and emits only a small amount of toxic gases. Phenolic foams can withstand temperatures of 191 ° C without serious decomposition. Phenolic foams have an ASTM E-84 Steiner tunnel flame spread value of about 5, a fuel contribution of about 0, and a smoke value of about 5.

Despite these advantages and the generally low cost, phenolic foams have not entered the thermal insulation market. The reason that phenolic foams have been unsuccessful is that the phenolic foams made so far have either had unsatisfactory thermal conductivity from the start or an undesirable increase in thermal conductivity over time. Furthermore, the compressive strength of the known phenolic foams is not as great as would be desirable for normal handling. It has also been reported that the known phenolic foams have serious brittleness and smoldering problems.

The general composition and process for making a phenolic foam is well known. Generally, a foamable phenolic resole composition is made by mixing an aqueous phenolic resole, a foaming agent, a surface active agent, optionally additives and an acid curing agent into a substantially uniform composition i5. The curing catalyst is added in an amount sufficient to initiate the curing reaction, which is highly exothermic. Due to the exothermic nature of the curing reaction, the foaming agent evaporates and expands, which foams the composition. The foaming process is preferably carried out in an essentially closed form.

The general procedure for the continuous manufacture of a phenolic foam insulation sheet is as follows. The foamable phenolic resole composition is prepared by continuously adding an aqueous phenolic resole, a foaming agent, a surface-active agent, optionally additives and an acid curing catalyst to a suitable mixing device. In the mixing device, these ingredients are combined into a substantially uniform composition which is applied evenly and continuously to a moving substrate, generally a protective layer, such as a cardboard, to which the foam adheres. The foaming composition is generally covered with another protective layer, such as a cardboard, that adheres to the foam. The covered foaming composition is then moved to a double wall press device where the exothermic curing 40 continues with evaporation and expansion of the foaming agent, thereby foaming the composition as it cures.

As mentioned, a major disadvantage of the known phenolic foam is the insufficient starting thermal conductivity (k value). It is believed that one of the main reasons that a phenolic foam has poor initial thermal conductivity is due to the cell walls breaking up during foaming and at the start of curing of the foamable phenolic resole-50 composition. This rupture leads to an immediate loss of the fluorocarbon foaming agent, which results in poor initial thermal conductivity. The broken cell walls also allow water to easily penetrate into the foam, which increases the thermal conductivity. The cracked cell walls are also believed to adversely affect the compressive strength and other properties of the phenolic foams. Another major reason for the poor initial thermal conductivity of phenolic foams is the loss of the fluorocarbon foaming agent before the cell walls of the foaming compositions are formed to a sufficient extent to contain the foaming agent.

As also mentioned, a further disadvantage of the 65 known phenolic foams is the undesirable increase in thermal conductivity over time (change in the k value). Even with the known foams that have cell walls that have not broken open and in which the

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Fluorocarbon is trapped in the cells, there is a tendency to lose the fluorocarbon foaming agent over time with a corresponding increase in thermal conductivity. Two main reasons for the increase in thermal conductivity over time are believed. The first and the main reason is the presence of small perforations or small holes in the cell walls. Through these small perforations, the fluorocarbon foaming agent can diffuse out over time and be replaced by air. This slow replacement with air leads to an increase in thermal conductivity and a decrease in thermal insulation value. Due to the small perforations, the phenolic foam can also absorb water, which further increases the thermal conductivity. The perforations are believed to be caused by water present in certain parts of the foamable composition, particularly in the catalyst.

The other main reason for the loss of thermal conductivity over time is the breakdown of the cell walls. In many known phenolic foams, the cell walls are very thin. When phenolic foams with thin cell walls are exposed to high temperatures, the cell walls dry out and break. Since thermal insulation is normally subject to heating and cooling cycles and the associated expansions and contractions, the breaking of the thin cell walls is further promoted. By breaking the cell walls, the fluorocarbon foaming agent can escape over time, increasing the thermal conductivity and decreasing the thermal insulation values.

Several methods are proposed in the prior art to overcome the problem of poor thermal conductivity. For example, one method involves a two-step process in which the foamable phenolic resole composition is initially foamed under vacuum, followed by curing at high temperatures and low pressures. This process creates a foam in which a substantial number of the cell walls are not broken, but there are still numerous cell walls that are either broken or have perforations, or are thin and easily fragile when exposed to thermal stress. This method is also unfavorable in terms of costs because of the equipment required and the time required.

Another method involves foaming and curing the foamable phenolic resoles at low temperatures (i.e., less than 66 ° C). This method also reduces the number of broken cells, but the phenolic foam formed still has thin cell walls and perforations. Another method relates to a method for foaming and curing the foamable phenolic resin composition while maintaining pressure on the foaming and curing composition. This method significantly reduces the number of broken cell walls, but the phenolic foam formed still has a significant number of broken cell walls or there may be a loss of foaming agent before the cell walls are cured, which may be thin.

Further attempts to improve the thermal conductivity of phenolic foams are based on developing specially modified phenolic resoles or surface-active agents, or on using certain additives in the foamable phenolic resole composition. None of these methods has proven successful in practice. Reference is made, for example, to U.S. Patents 3,389,094, 3,821,337, 3,968,300, 3,876,620, 4,033,910.4 133,931, 3,385,010 and 4,303,758.

It has now been found that the breaking up of the cell walls during foaming, the loss of the foaming agent before the cell walls have formed sufficiently to enclose the foaming agent, and the formation of thin cell walls are directly related to the phenolic resole used to make the phenolic foam is used.

Accordingly, it is an object of the invention to provide an improved aqueous phenolic resole which results in a phenolic foam, the cell walls of which have essentially no openings, which does not lose any foaming agent before the cell walls are sufficiently formed to enclose the foaming agent, and the like Cell walls are essentially not subject to cracking due to drying and expansion and contraction.

The subject of the invention is a foamable aqueous composition containing phenolic formaldehyde resols which is suitable for the production of phenolic foam insulation, which has good thermal insulation properties, good compressive strength and good properties in terms of the density, fragility and other properties required for a commercial application are. The composition is defined in claim 1.

The invention further relates to the use for the production of phenolic foams from such compositions as defined in claim 7.

The aqueous phenol formaldehyde resol has a molar ratio of formaldehyde: phenol of 1.75: 1 to 2.25: 1 and particularly preferably of about 2: 1. The phenolic resol has a weight-average molecular weight, determined by gel permeation chromatography (GPC), of more than 800 and preferably of about 950 to 1500. The resol further has a number average molecular weight, determined by GPC, of more than 350, preferably about 400 to about 500, and a polydispersity of more than 1.7, preferably of about 1.8 to 2.6. Phenol formaldehyde resoles which have these properties can be processed reliably and reproducibly according to the invention into closed cell phenolic foams which have an initial k value of 0.10 to 1.13 and a compressive strength of 13,700 to 24,000 Pa and have a density of 0.024 to 0.080 g / cm3. The foam still has excellent fire values.

The aqueous phenol formaldehyde resole can be prepared by any known standard method for the preparation of aqueous phenolic resoles. A preferred process for the preparation of the aqueous phenolic resoles involves the reaction of highly concentrated aqueous phenol (more than 88% by weight) with highly concentrated formaldehyde (more than 85% by weight) in the presence of an alkaline catalyst in a concentration which is somewhat greater than that normally used in the manufacture of phenolic resoles. According to the preferred method, the formaldehyde is added gradually or continuously during the first part of the condensation reaction to a mixture of the phenol and the alkaline catalyst.

The aqueous phenol formaldehydes are generally formulated into foamable compositions which, in addition to the aqueous phenolic resole, contain a surface active agent, a foaming agent, optional additives and an acid foaming and curing catalyst. The foamable compositions result in a phenolic foam with improved properties, especially s

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improved thermal insulation properties compared to the known phenolic foams.

In the drawings, in which the same reference numerals represent the same parts, show:

Figures 1A and 1B schematically, partly in cross-section, an essentially closed mold which is used to produce a phenolic foam in the laboratory;

FIG. 2 schematically shows a side view of a cross section through a device of the two-band type for the continuous production of a phenolic foam;

Figure 3 schematically shows a section along the line

III-III of Figure 2;

Figure 4 schematically shows a cross section along the line

IV-IV of Figure 3;

Figure 5 schematically shows a cross section along the line

V-V according to Figure 3; and

Figures 6 through 22 are scanned electron micrographs (SEM) showing the cells and cell walls of phenolic foams representative of the invention and illustrating the invention. All SEM are magnified 400 times unless otherwise stated.

As mentioned above, there is a great desire to use phenolic foams for thermal insulation, especially for roofs, walls and pipes, since phenolic foams have excellent fire properties. However, the previously known phenolic foams suffer from a generally unacceptable starting k-factor or from their inability to maintain a low k-factor over a long period of time. The thermal insulation ability of a foamed material can generally be assessed by the thermal conductivity or the k-value. The thermal conductivity or k value of a particular insulation material is measured according to the revised ASTM method C-518, its dimension usually being expressed as' BTU per inch per hour per square foot per ° F. To convert the k-value into the corresponding FI unit watt per centimeter per hour per square meter per ° C, it is sufficient to multiply the k-values given here by 0.144. The lower the k value, the better the insulating properties of the material. The longer the foam maintains a low k value, the better the insulating effectiveness of the material.

A low k value is generally understood to mean a k value which is substantially below approximately 0.22, which corresponds approximately to the k value of the air. A low initial k-value is understood to mean a k-value that is substantially below 0.22, measured after the water content of the foam has reached equilibrium after its production, generally after five days. It has been found that the phenolic foam according to the invention leads to a k value which decreases during the first days when the water content of the phenolic foam is in equilibrium with the surroundings. After that, the k-factor remains constant. The phenolic foams according to the invention have an initial k-factor, measured by the ASTM method, of less than 0.15 and are generally in the range between 0.10 and 0.13. The preferred foams according to the invention have a k-value of less than 0.10 if a low water content is found. Phenolic foams can be produced that permanently maintain this low k value.

Phenolic foams which are produced from the compositions according to the invention based on aqueous phenolic resoles generally have a total density (including the foam cover layer) of about

24 to about 80 kg / m3, preferably from about 32 to about 64 kg / m3, and a core density (without the foam cover layer) from about 24 to about 72 kg / m3, preferably from about 32 to about 56 kg / m3. The phenolic foams are essentially closed cell foams (ie, essentially without broken cell walls), generally having at least 90 to 95% closed cells and typically more than 95% closed cells, as measured, for example, with an ASTM D air pycnometer -2865-80 (1976).

The k value of a phenolic foam is directly dependent on the ability of the foamable phenolic resole composition to enclose the foaming agent during foaming and curing and to retain the foaming agent permanently. The thermal conductivity of a phenolic foam is directly dependent on the thermal conductivity of the enclosed gas. In the case of a phenolic foam which only contains air, a k value of about 0.22 can be expected. A phenolic foam containing a fluorocarbon is expected to have a k value that approximates the thermal conductivity of the encapsulated fluorocarbon. Commercial fluorocarbons have k values around 0.10. An excellent phenolic foam will therefore have a k-value around 0.10 and maintain this k-value permanently. The phenolic foams according to the invention generally have such k values and maintain these k values permanently.

As mentioned, it is believed that the generally poor k value of the known phenolic foam is due to two main causes. One cause is the loss of the foaming agent before the cell walls have hardened enough to trap the foaming agent. The other cause is the breakage of the cell walls during foaming. As also mentioned, it is believed that the decrease in thermal insulation over time is caused by many small perforations found in the cell walls, as well as by the breaking of the thin cell walls by thermal stress.

The main cause of cell wall rupture is the pressure caused by the expanding foaming agent during the formation of the phenolic foam. At the temperatures generally used for the industrial production of phenolic foams (ie 51 to 121 ° C.), the pressure exerted by the foaming agent during foaming and curing is greater than that which the cell walls can withstand, especially during the first period of foaming and curing. The cell walls of the phenolic foams produced with the known resols cannot withstand large pressures until the foaming has been completed and substantial curing has taken place. The expanding foaming agent therefore breaks up the cells before they have hardened sufficiently, thereby forming a foam with unacceptable thermal conductivity properties.

Another reason for the rupture of the cell walls is the presence of water in the foamable phenolic resole composition, especially the water that is present in the catalyst system. The rupture of the cell walls due to the water in the foamable phenolic resole composition, particularly the catalyst, is not as severe as the rupture due to the fact that the foaming composition does not contain a force of at least the same order of magnitude as the pressure which is exerted on the foaming composition,

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as severe as the breakup, which is due to the use of a resol that has too strong and too fast exothermic properties. Although measures to prevent the cell walls from being broken open are proposed, they do not prevent the breakdown of all the cell walls. If the composition according to the invention based on phenolic resoles is used, phenolic foams can be produced which have essentially no broken cell walls.

The loss of the foaming agent before the cell walls have solidified sufficiently to trap the foaming agent is determined by two interdependent factors. First, the known resols are very reactive. When amounts of the acid curing agent sufficient to foam and cure the resole in an acceptable time are added to these resoles, they are heated exothermically very quickly, reaching maximum temperatures well in excess of 93 ° C. This rapid and highly exothermic reaction releases most of the foaming agent before the cell walls are sufficiently formed to retain the foaming agent. The result is a phenolic foam with only a small amount of foaming agent trapped in the cells. In addition, a rapid and exothermic reaction leads to a break in the cell walls, even if an inclusion or counterforce is exerted. The known resols also have a low viscosity, especially when they are formulated with foamable compositions, surface-active agents, foaming agents and acid catalysts. As the temperature of the foamable composition increases at the start of foaming, the viscosity of the resin is significantly reduced, and does not increase until substantial resole crosslinking has occurred. Cell walls formed from a low viscosity resin are unable to trap and retain the foaming agent until substantial curing has occurred. Accordingly, much of the foaming agent is lost before the cell walls are firm enough to form a phenolic foam with little or no foaming agent included.

The formation of the cell walls, which are very thin and break when exposed to thermal stress, is also caused by resols which show an exothermic reaction which is too fast and too strong and which have a low viscosity. As mentioned above, the viscosity of the phenolic resin decreases with increasing temperature of the foamable composition at the beginning of the foaming and curing, in any case it does not increase appreciably until substantial crosslinking has taken place. During this time, that is until the viscosity of the phenolic resin increases noticeably, the phenolic resin which forms the cell walls has the property of flowing away. The flow away is accompanied by an increasing thinning of the cell walls and a thickening of the scaffold. If too much flows away before the cell walls have hardened sufficiently, the cell walls formed are very thin. Thin cell walls continue to be easily broken up by the foaming agent and break easily when exposed to high temperatures, drying or normal expansion or contraction.

The phenolic resole used according to the invention is an improved resole compared to the known aqueous phenolic resoles. It is known to catalyze the condensation of phenol and formaldehyde in aqueous solutions to produce liquid condensates,

which are generally called resols. As discussed and known in the present context, the aqueous phenolic resoles are easily cured into crosslinked, higher molecular weight, thermoset resins. The curing reaction is highly exothermic and is accelerated considerably by acidic substances. The known aqueous resols can be combined with foaming agents, surface-active agents and curing agents and optional additives to form a foamable composition which can be foamed and cured to form a phenolic resin. However, the known resols have two disadvantages. This is because they lead to an exothermic reaction that reaches too high a temperature and a too rapid one, and they have a viscosity that is too low. When the known resoles are used in conjunction with the amount of acid catalyst required to foam and cure the composition in an acceptable time, the heat is released too quickly and results in an excessive temperature. As a result, either the cell walls of the foam formed are broken open or the foaming agent flows out before the cell walls are sufficiently firm to enclose the foaming agent. In both cases a phenolic foam is obtained which has a poor starting k value. On the other hand, the viscosity of the known resols is low, especially when they are formulated as foamable compositions. The low viscosity allows the foaming agent to exit before the cell walls are firm enough to trap the foaming agent, with the phenolic resole flowing from the cell walls into the struts and webs or scaffold when foamed, thereby creating very thin cell walls arise that break under normal use. This also results in a phenolic foam with unacceptable thermal insulation properties.

In comparison, the aqueous phenolic resoles which are used according to the invention do not have the disadvantages mentioned above. When formulated in foamable compositions and cured with an amount of the anhydrous arylsulfonic acid required to foam and cure the composition in an economically acceptable time, the exothermic reaction of the resols is not too rapid and does not result in high temperatures . The preferred foamable phenolic resole-containing compositions according to the invention reach a maximum pressure within 2 to 3 minutes after the anhydrous arylsulfonic acid has been added. During this period the temperature of the foaming compositions reaches about 73 to 80 ° C. The temperature never exceeds 88 ° C during this period. The maximum temperature generated during this period is at most 93 ° C and preferably does not exceed 88 ° C. The overpressure generated by the preferred resoles and foamable resole compositions is generally from 27 530 to 41 230 Pa. Accordingly, phenolic foams can be made which contain substantially all of the foaming agent and which have cell walls that are not broken open. In addition, the viscosity of the foamable resole compositions is high enough to include the foaming agent during the initial stage, and they do not go off noticeably, so that thicker and thicker cell walls are formed.

The aqueous phenolic resole used according to the invention is a phenol formaldehyde condensation polymer with a molar ratio of formaldehyde: phenol of 1.75: 1

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up to 2.25: 1 and very particularly preferably from about 2: 1. The phenolic resole has a weight average molecular weight of more than 800, preferably from about 950 to 1500. The phenolic resole has a number average molecular weight of more than 350, preferably from about 400 to about 600, and a polydispersity in water of more than 1 , 7, preferably from about 1.8 to 2.6. The aqueous phenolic resole can be a mixture of more than one resole, provided that the resole formed has the required properties.

The aqueous phenol formaldehyde resoles are generally prepared by reacting phenol and formaldehyde in the desired molar ratio in the presence of a basic catalyst until the phenolic resoles formed have the required molecular weight and the required polydispersity. The reaction can be carried out by any known method. For example, the phenol, formaldehyde and a catalyst can be added in a reactor in the desired molar ratio and reacted until the desired molecular weight is reached. Instead, one or two components can be added to the reactor and the remaining components can be gradually added to the reaction mixture. In a preferred process for the preparation of the aqueous phenolic resole, the phenol and the basic catalyst are added to the reactor and the formaldehyde is metered in stepwise or continuously during the first section of the condensation reaction. The process for making the phenolic resin is not critical provided the phenol and formaldehyde are condensed in the desired molar ratio and the required molecular weight and polydispersity properties are available.

As mentioned, the phenolic resole must have a molecular weight of formaldehyde: phenol of 1.75: 1 to 2.25: 1. If the ratio is greater than 2.3: 1, the phenolic foam formed has a residual free formaldehyde content which can lead to odor problems. In addition, larger molar ratios result in phenolic resoles, which lead to an exothermic reaction which is too slow and which have too high a processing viscosity. Phenolic foams made from resols that have a higher molar ratio also tend to be too brittle and have poor compressive strength. If the molar ratio is less than 1.75: 1, the resol has too low a viscosity, which results in thin cell walls. Phenolic resoles with a molar ratio of less than 1.75: 1 also lead to a strong exothermic reaction, which makes it difficult to enclose the foaming agent and to prevent the cell walls from breaking through. Phenolic foams made from these resins also show excessive shrinkage.

The phenolic resole must have a weight average molecular weight of more than 800, preferably between 950 and 1500. If the weight average molecular weight is less than 800, then the phenolic resin is too reactive and not viscous enough. Phenolic resins, whose weight average molecular weight is less than 800, lead to a pressure and an exothermic temperature maximum, both of which are too fast and too high. These resoles also reach an exothermic temperature that is greater than 93 ° C during this period. This rapid and high exothermic reaction causes numerous cell walls to be broken and fluorocarbon foaming agents to be lost before the cells are formed. In addition, phenolic resins with a weight average molecular weight of less than 800 result in foamable phenolic resole compositions that are not sufficiently viscous to form thick cell walls. The phenolic resin tends to drain from the cell walls into the framework during foaming and at the start of curing, thereby forming thin cell walls. The thin cell walls are easily broken up by the expanding foaming agent and have a tendency to

break after drying and during use.

The upper limit of the weight average molecular weight is a practically predetermined limit. Resoles that have a molecular weight greater than 1500 tend to be very viscous and very difficult to handle. However, they can be processed into acceptable foams.

The phenolic resoles have a number average molecular weight of more than 350, preferably of about 400 to 600 and a polydispersity of more than 1.7, preferably 1.8 to 2.6. If the number average molecular weight is less than 350 or the polydispersity is less than 1.7, the phenolic resole is too low in viscosity. Furthermore, the phenolic resole is too reactive, i.e. it leads to an exothermic reaction which is too high and too fast. It is difficult to trap the foaming agent and prevent the cell walls from breaking open. Phenolic foams made from these resoles also have a shrinkage problem and thin cell walls. If the number average molecular weight is greater than about 600 and the dispersibility is greater than 2.6, the resoles tend to be too viscous to be handled and to react too slowly. These upper values represent practically predetermined limits, it being possible for acceptable foams to be produced from resols which have a number average molecular weight and a dispersibility which exceed these limits.

The phenolic resoles used according to the invention have a free formaldehyde content of up to 7% by weight of the resole and a free phenol content of up to 7% by weight. Preferably the free formaldehyde and phenol content is less than about 4% by weight. Too much free formaldehyde can lead to odor problems. In addition, free formaldehyde and phenol affect the reactivity and viscosity of the aqueous phenolic resole and foamable compositions.

The phenolic resoles generally have a viscosity of about 1000 centipoises to about 20 Pas at 16% water and 25 ° C. The viscosity is preferably between about 6000 and 10 Pas. The viscosity is not a critical factor, provided the molar ratios, molecular weights and polydispersity are as described here. It is possible to produce phenolic resoles which have the above viscosities but do not have the required molecular weights and the required polydispersity. Such resols are not the subject of the invention. Resoles that have viscosities within the above range, particularly the preferred range, are desirable because they can be easily formulated into uniform foamable phenolic resole compositions using conventional devices.

In addition to phenol itself, other phenolic compounds can replace the phenol up to about 10% by weight. Examples of other suitable phenolic compounds are resorcinol, catechol, ortho, meta and para cresol; Xy-lol, ethylphenol, p-tert-butylphenol and the like. Binuclear phenolic compounds can also ver6

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be applied. The preferred phenolic resoles mainly contain phenol itself with only minor amounts, if any, of other phenolic compounds. In addition to formaldehyde itself, other aldehydes can replace formaldehyde by up to about 10%. Examples of other suitable aldehydes are glyoxal, acetaldehyde, chloral, furfural and benzaldehyde. The preferred phenolic resoles mainly contain formaldehyde even with small amounts, if any, of other aldehydes. In the present case, the term phenolic resole is also to be understood as meaning resols which contain small amounts of phenolic compounds other than phenol or small amounts of other aldehydes than formaldehyde.

The phenol is generally added to the reactor as a reactant in an aqueous solution. The concentration of the phenol can vary between about 50% and about 95% by weight. Solutions containing less than 50% by weight can be used, but the reaction mixture formed is very dilute and accordingly the reaction time required to obtain a resol with the desired molecular weight is increased. It is also possible to use pure phenol. However, no benefit is achieved when pure phenol is used compared to an aqueous phenolic solution at a concentration greater than about 85% by weight. According to a preferred embodiment, phenolic solutions with more than 88% by weight are used.

The formaldehyde is added as a reactant to the condensation reaction as a component in a concentration of about 30 to about 97% by weight. Solutions containing less than about 30% by weight formaldehyde can be used, but the reaction mixtures formed are very dilute, increasing the reaction time required to achieve the desired molecular weight. In a preferred embodiment, concentrated formaldehyde sources of more than 85% by weight are used. In a preferred embodiment, para-formaldehyde is used as the formaldehyde source.

The condensation of the phenol with the formaldehyde is catalyzed under basic conditions. The basic catalysts that are generally used are the alkali and alkaline earth metal hydroxides, carbonates, bicarbonates or oxides. However, other basic compounds can also be used. Examples of suitable catalysts are lithium hydroxide, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium oxide, potassium carbonate and the like. The catalysts which are generally used are sodium hydroxide, barium hydroxide and potassium hydroxide. In the preferred embodiment, potassium hydroxide is used.

Although the molar ratios of phenol to formaldehyde are critical, other parameters of the condensation reaction, such as time, temperature, pressure, catalyst concentration, reactant concentration, and the like, are not critical. These parameters can be adjusted to obtain a phenolic resole that has the desired molecular weight and dispersibility. It should be emphasized that in the preferred embodiment, the concentration of the phenol, formaldehyde and catalyst are very important.

The reaction of the phenol and formaldehyde is generally carried out at a temperature between 50 and 150 ° C. The preferred reaction temperature is between 70 and 95 ° C. It should be emphasized that the reaction time depends on the temperature.

The reaction pressure can vary over a wide range from 101 325 Pa (atmospheric pressure) to six times that. The reaction can also be carried out under reduced pressure.

The catalyst concentration can be between about 0.005 and about 0.10 moles of base per mole of phenol. Preferably the range is about 0.005 to about 0.03. In the most preferred embodiment, catalyst concentrations of about 0.10 to 0.020 mole base per mole phenol are used.

The condensation reaction time depends on the temperature, the concentrations of the reactants and the amount of the catalyst used. Generally the reaction time is at least 6 hours but not more than 20 hours. It should be emphasized that the reaction proceeds until the phenolic resole has the desired molecular weight and dispersibility.

The time to complete the reaction can be determined by determining the molecular weights and polydispersity described above. However, this is time consuming and there is a time gap before the results of the determination are completed. However, it has been found that there is a close relationship between bubble viscosity and molecular weights and dispersity for a given set of molar ratios and operating parameters. For example, a preferred industrial method of making a 2: 1 molar ratio resol using concentrated phenol, concentrated formaldehyde and a high catalyst content has been found to have a bubble viscosity of 60 seconds correlated with molecular weights and polydispersity within the preferred ranges. It is therefore possible to consider the bubble viscosity as an indication of when the desired molecular weights and the desired polydispersity have been reached. Control is however exerted by the actual molecular weights and the actual polydispersity. In addition, if any changes in the molar ratios or operating parameters of the process are made, the bubble viscosity / molecular weight-polydispersity relationship must be determined for these particular conditions.

Since the condensation reaction is catalyzed by a base, the phenolic resole formed is alkaline. It is desirable to adjust the pH of the phenolic resole to about 4.5 to about 7.0, preferably 5.0 to 6.0, to prevent further condensation reactions. The pH of the resol is adjusted by adding an acid or an acid-forming compound. Examples of acids that can be used

are hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid and formic acid. The preferred acid is formic acid.

The phenol formaldehyde resol is thus obtained as an aqueous solution with a resole content of about 25 to about 90% by weight. The final concentration depends on how much water has been introduced with the reactants and the catalysts, which are generally used as aqueous solutions. In addition, water is formed as a by-product of the condensation reaction. In a preferred embodiment, the phenolic resole formed has a concentration of about 80 to 90% by weight resole. The concentration of the phenolic resole to a certain predetermined water content is generally achieved in a simple manner by evaporation in a conventional manner at reduced pressure and low temperature.

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In the preparation of the phenol formaldehyde resol used according to the invention, the phenol and the formaldehyde are generally reacted in the presence of a basic catalyst until the resol has the desired molecular weight and the desired dispersibility. The pH of the aqueous resol is then adjusted and the resol is cooled to about 20 ° C. It should be emphasized that if the pH-adjusted aqueous resole is too low in molecular weight, it can be thickened further until the desired molecular weight is reached. The thickening of pH-adjusted resols to increase the molecular weight is known. However, since such thickening is slow compared to the base catalyzed reaction, it is desirable to initially convert and thicken the phenol and formaldehyde to the desired molecular weight before adjusting the pH and cooling the mixture.

The formaldehyde resoles described above are used to make a phenolic foam. The aqueous phenolic resoles are first formulated into a foamable phenolic resole composition which comprises the aqueous phenolic resole, a foaming agent, in particular a fluorocarbon, a surface-active agent, an acid catalyst and optional additives such as plasticizers, formaldehyde scavengers and the like.

The process for making the phenolic foam, generally speaking, involves supplying the foamable phenolic resole compositions to a substantially closed form, the composition being allowed to foam and cure in this form. The shape can withstand the pressure generated by the foaming compositions. The magnitude of the pressure depends on such factors as the amount and kind of the foaming agent, the amount and kind of the acid catalyst, and the amount and kind of the resol. In general, the pressure which the resols according to the invention generate can be 20 661 to 103 308 Pa above atmospheric pressure. The shape should therefore be built accordingly. The preferred resoles, when formulated into the preferred foamable compositions, generate a pressure of 27 530 to 41 230 Pa above atmospheric pressure. The shape should withstand approximately the same pressures generated by the foaming composition to prevent the cell walls from breaking open. The amount of the foamable phenolic resole composition that is added to the mold depends on the desired density, etc. of the phenolic foam.

The numerous components of the foamable phenolic resole composition can be mixed together in any order, provided that the composition formed is uniform. It should be noted, however, that the preferred anhydrous arylsulfonic acid catalyst results in the foamable composition starting to foam within seconds when mixed with the phenolic resole and the foaming composition reaching a maximum pressure within minutes. The catalyst should therefore be the last ingredient added to the foamable phenolic resole composition. In the preferred continuous method, some components are premixed before being metered into the mixer. For the reasons given above, however, the catalyst should be the last ingredient to be added to the mixer.

According to one embodiment of the invention, which is normally used in the laboratory, the foamable phenolic resole composition is placed in a rigid, closed form, as shown, for example, in FIGS. 1A and 1B. The foamable phenolic resole composition initially expands essentially under atmospheric pressure. As the foamable composition expands to fill the mold, pressure is created against the walls of the mold. The mold is designed to withstand pressures in excess of 103 308 Pa above atmospheric pressure.

According to FIGS. 1A and 1B, the shape consists of an upper plate 1, a lower plate 2, side walls 3 and end walls 4. The side walls 3 and an end wall 4 are held together by hinges 5. In the closed position, the upper and lower plates and the side walls are held in place by bolts 6 and wing screws 7. In order to withstand a pressure of more than 103 441 Pa, a plurality of clamps 8 are also arranged around the circumference of the mold during the foaming and curing. The mold is further provided with a pressure gauge 9 to measure the pressure in the mold and with a thermocouple 10 to measure the temperature in the mold. The operation of the laboratory form is described in detail below. The size of the shape can be changed by changing the dimensions of the walls and panels.

In another embodiment of the invention using a preferred continuous processing technique, the phenolic foam is produced in a double belt press type apparatus as shown schematically in Figures 2-5. The constituents of the foamable phenolic resole composition are dosed in suitable proportions into a suitable mixing device (not shown) and then onto a lower feed material 25, for example a cardboard box containing a thin aluminum layer, a glass mat, a solid substrate such as a hard cardboard or a hardboard or placed on a vinyl film, the material exiting from a container (not shown) and moving along the table 29 by means of the lower conveyor 12. The foamable phenolic resole composition of the invention is applied with a suitable dispenser 30 which reciprocates across the direction of travel of the lower material 25, although other suitable devices for evenly distributing the composition may be used, for example a multi-flow mixing head or a series of nozzles. When the foamable composition is transported downstream, it foams and is brought into contact with an upper cover material 27 which is fed by means of rollers 22 and 23 to the area in which the foamable composition is in a very early stage of expansion. When the foamable composition initially expands substantially under normal atmospheric pressure, it is conveyed into a curing recess 28 formed between the lower section of the upper conveyor 11 and the upper section of the lower conveyor 12, as well as two fixed rigid side walls, the side guides are called and not shown in Figure 2, but are designated in Figure 3 with 41 and 42. The thickness of the foam is determined by the distance of the upper conveyor 11 from the lower conveyor 12. The upper conveyor 11 can be moved by any suitable lifting device (not shown) perpendicular to the lower conveyor 12, which in turn can neither be raised nor lowered. When the upper conveyor 11 is raised or lowered, it moves between the fixed rigid side walls 41 and 42 shown in FIG. 3, which walls 42 and 43 immediately the sides of the upper conveyor 8

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rers 11 are adjacent. The surfaces of the conveyor that contact the top and bottom cover materials include a plurality of pressure plates 13 and 14 attached to the conveyor by rigid connecting means. The pressure plates can, if necessary, be heated with hot air which is introduced into the upper and lower conveyors and circulated therein by means of air ducts, not shown in the drawing.

Simultaneously with the upper and the lower cover paper, side papers 43 and 44, which contain a foam-releasing material, such as a thin polyethylene film, are fed into the curing recess by means of rollers 45 and 46 as well as with guide rails 47 and 50. Each of the guide rails 47 and 50 is arranged immediately in front of the curing recess 28 so that the side papers 43 and 44 overlap the upper and the lower cover material, for example as shown in FIG. 4, before they come into contact with the side walls 41 and 42. When the side papers 43 and 44 come into contact with the side walls 41 and 42, they are made flat as shown in FIG.

When the foam has expanded to fill the thickness of the curing recess, further expansion is prevented by the pressure plates 13 and 14, as shown in Figure 2, as well as by the side walls 41 and 42, as illustrated in Figure 3. The pressure applied to the foam through the pressure plates and side walls will change as described herein, but will typically range from about 20,661 to about 103,308 Pa. The pressure plates 13 and 14 and the side walls 41 and 42 are designed to withstand this pressure. The processing parameters, such as the amount of components of the foamable phenolic resole composition, the flow rate of the composition from the distributor, and the conveyor speed can be varied over a wide range to produce a phenolic foam having the desired thickness, density, etc. Sufficient foamable composition must be used to ensure that the foaming composition fills the curing recess and exerts pressure against the recess walls.

After the phenolic foam has left the curing recess, the side papers 43 and 44 are removed, for example with the rollers 48 and 49, as shown in FIG. 3. The foam can be cut to the desired length depending on the intended use.

The amount of aqueous phenolic resole present in the foaming phenolic resole compositions to produce substantially closed cell phenolic foams can vary widely, provided that the amount is sufficient to produce a foam that has the desired density and Has compressive strength. Generally, the amount of phenolic resole present in the foamable composition is 40 to 70% by weight of the composition. An amount in the range between about 45 and about 55% by weight of the foamable composition is preferred. The weight percent of the phenolic resole is based on 100% active phenolic resole. Since the resol is an aqueous solution, the actual concentration of the resol must be used as a basis, by calculating how much aqueous resol solution goes into the foamable phenolic resol composition.

Any suitable foaming agent can be used. When choosing the foaming agent, it should be borne in mind that the k value of the phenolic foam is directly dependent on the k value of the foaming agent enclosed in the phenolic foam. Although foaming agents such as n-pentane, methylene chloride, chloroform and carbon tetrachloride can be used, they are not preferred because they do not have the excellent thermal insulation properties of fluorocarbon foaming agents. In addition, fluorocarbon foaming agents are insoluble in the phenolic foam and therefore do not diffuse out over time, while some of the above foaming agents have some compatibility with the phenolic foam and can therefore diffuse out over time. However, they can be used in conjunction with the preferred fluorocarbon foaming agents. Examples of suitable fluorocarbon foaming agents include dichlorodifluoromethane; 1,2-dichloro-1,1,2,2-tetrafluoroethane; 1,1,1-richlor-2,2,2-trifluoroethane; Trichloromonofluoromethane and 1,1,2-trichloro-1,2,2-trifluoroethane. The foaming agent preferably has a chlorofluorocarbon foaming agent. The foaming agent can be a single foaming agent compound or a mixture of such compounds. In general, fluorocarbon foaming agents having a boiling point at atmospheric pressure, i.e. at an absolute pressure of 101 325 Pa mercury, used in a range from about - 5 ° to about + 55 ° C. A boiling point at atmospheric pressure in the range of about 20 to about 50 ° C is typical. A preferred foaming agent is a mixture of trichloromonofluoromethane and l, l, 2-trichloro-l, 2,2-trifluoroethane. It is particularly preferred that the weight ratio of the trichloromonofluoromethane to the 1,1,2-trichloro-1,2,2-trifluoroethane in the mixture be about 1: 1 to about 1: 3.

The foaming agent is generally present in the foamable composition in an amount that essentially produces a closed cell phenolic foam that has a low initial k value. The amount of the foaming agent can vary within wide limits, but it generally varies between about 5 and about 20% by weight of the foamable composition. Typically, the amount of the foaming agent ranges from about 5 to about 15% by weight of the foamable composition. An amount in the range of about 8 to about 12% by weight is preferred.

The foamable phenolic resole composition also contains a surfactant. The surfactant has properties that enable it to effectively convert the phenolic resole, foaming agent, catalyst, and optional additives of the foamable composition into an emulsion. To make a good foam, the surfactant should have a low surface tension and stabilize the foam cells during expansion. It has been found that non-ionic, non-hydrolyzable silicone glycols are very suitable as surfactants, although any surfactant with the desired properties described above can be used. Specific examples of suitable surfactants include L-7003 silicone, L-5350 silicone, L-5420 silicone and L-5340 silicone (which is preferred), all of which are from Union Carbide Corporation, and SF1188 silicone, from the General Electric Company. Other classes of surfactants that can be used are non-ionic organic surfactants such as condensation products of alkene oxides, e.g. ethylene oxide, propylene oxide, or mixtures thereof, and alkylphenols, e.g. nonylphenol, dodecylphenol and the like. Other suitable organic surfaces5

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active agents are known and include, for example, those described in U.S. Patent 3,389,094, which reference is hereby made to organic surfactants.

Other classes of suitable surfactants that can be used in the practice of the present invention include siloxane-oxyalkylene copolymers, such as those containing Si-O-C and Si-C bonds. Typical siloxane-oxyalkylene copolymers contain a siloxane component which is composed of recurring dimethylsiloxy units which are blocked at the ends with monomethylsiloxy and / or trimethylsiloxy units and at least one polyoxyalkylene chain which consists of There are oxyethylene and / or oxypropylene units blocked with organic groups such as an ethyl group. Specific examples of suitable siloxane-oxyalkylene polymers are described in US Pat. No. 3,271,331, which is incorporated herein by reference with respect to siloxane-oxyalkylene surfactants. The choice of surfactant must be made carefully because some surfactants adversely affect the viscosity of the foamable phenolic resole composition or cause the foam to collapse before it is cured.

The surfactant used in the foamable composition can be a single surfactant or a mixture of surfactants. The surfactant is used in the invention in an amount sufficient to form a good emulsion. Generally, the amount of surfactant is from about 0.1 to about 10% by weight of the foamable phenolic resole composition. Typical for the amount of surfactant is from about 1 to about 6% by weight of the composition. An amount of the surfactant of 2 to 4% by weight of the composition is preferred.

The surfactant can be mixed separately with the phenolic resole, the foaming agent and the catalyst to form a foamable phenolic resole composition, or it can be added to the phenolic resole or the foaming agent before the other components are mixed.

Instead, part of the surfactant can be premixed with the phenolic resole and part can be premixed with the foaming agent. It is preferred to premix about 11% of the surfactant with the fluorocarbon foaming agent and 2% with the phenolic resole.

Although it is believed that water is the main cause of perforations in the cell walls and contributes to the breakdown of the cell walls, the presence of water is necessary. First, it is very difficult and expensive to make a phenolic resole that contains little or no water. In addition, phenolic resoles which have the properties of the resoles used according to the invention are very difficult to handle without water. They are very viscous and difficult to formulate foamable compositions. In addition, it is difficult to control the exothermic reaction without water. Accordingly, water is required in the foamable phenolic resole composition to adjust the viscosity of the phenolic resole and the foamable phenolic resole composition such that it is beneficial for the manufacture of phenolic foams. Water is also desired to absorb heat and to help control exothermic foaming and curing. Most of the water is present in the aqueous phenolic resole, although very small amounts can be tolerated in the fluorocarbon foaming agent or in the surfactant. Only small amounts can be tolerated in the anhydrous arylsulfonic acid catalyst. The foamable phenolic resole composition contains at least about 5% water. A water concentration of more than 20% should be avoided since even the preferred catalyst cannot repel enough water to substantially eliminate breakthroughs and perforations when this excess water is originally present in the foamable composition. An amount of about 7 to about 16% by weight is preferred. As mentioned above, limited amounts of water can be tolerated in the foaming agent, surfactant, or catalyst if the phenolic foam has cell walls that have no perforations or perforations caused by water. It is also important that the water in the aqueous resole is evenly mixed with the resole. If the aqueous resol contains water that is not evenly mixed with the resol, broken cell walls can result.

The acid catalyst component of the foamable phenolic resole composition can be any strong organic or inorganic acid, i.e. with a pKa less than about 2.0. Examples of strong inorganic acids are hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. Examples of strong organic acids are trichloroacetic acid, pigrinic acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, phenolsulfonic acid, methanesulfonic acid, ethanesulfonic acid, butanesulfonic acid and the like. Mixtures of several of the acids listed above can also be used.

As described, a disadvantage of the known phenolic foams is that there are small perforations in the cell walls. It is believed that water, especially water present in the catalyst, is the primary cause of cell wall perforations and also contributes to cell wall breakage. Accordingly, the acids used should contain as little water as possible. The preferred catalysts are certain anhydrous aryl sulfonic acids. Of the anhydrous aryl sulfonic acids, toluenesulfonic acid and xylene sulfonic acid are preferred, mixtures of these two being very particularly preferred.

The amount of acid curing catalyst in the foamable phenolic resole composition can vary within a relatively wide range. A practical limit to the amount of catalyst used is the amount that results in a rise time of about 10 seconds to 1 minute and a curing time of about 0.5 to 5 minutes. In general, the amount of the catalyst, based on the anhydrous catalyst, is about 6 to 20% by weight of the foamable composition, preferably about 12 to 16% by weight.

In addition to the aqueous phenolic resole, the foaming agent, the anhydrous arylsulfonic acid and the surface-active agent, the foamable phenolic resole compositions can contain other known substances in known amounts for known purposes. Examples of such optional components are as follows. Urea and resorcinol can be added to bind free formaldehyde, generally in an amount of 0.5 to 5.0% by weight. Plasticizers, such as triphenyl phosphates, dimethyl terephthalate or dimethyl isophthalate, can also be added in amounts of essentially about 0.5 to 5% by weight. Anti-glow agent, agent against

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Flaking and anti-glow agents can also be added in the usual amounts of 0.5 to 5% by weight. Preferred foamable phenolic resole compositions contain about 3% by weight of urea and about 3% by weight of plasticizer. The urea and plasticizer are preferably premixed with the phenolic resole before it is mixed with the other components of the foamable phenolic resole composition.

The aqueous phenolic resoles are suitable as foundry binders, wood adhesives, binders for plywood and chipboard as well as molded compounds with low shrinkage. However, the aqueous phenolic resoles are particularly suitable for the production of phenolic foam thermal insulation for a wide variety of purposes in the household and in industry. The invention is particularly advantageous for a process for the production of phenolic foams with excellent insulating properties from foamable compositions based on phenolic resoles, which are produced from phenol and formaldehyde, in particular para-formaldehyde, at relatively low costs. The phenolic foam, which is produced from the resols used according to the invention, not only has a good starting k value, but also a good retention of the k value, in contrast to the generally known phenolic foams. The resol compositions according to the invention thus achieve a long-sought, but not yet achievable goal, namely the production of a phenolic foam which has both a good starting k value and good retention of the k value, and from such simple ones phenolic resoles such as phenol formaldehyde resoles, making important progress in the field of phenolic foams.

The values of the numerous properties of the phenolic resoles and the phenolic foam produced therefrom were determined by the following methods, unless stated otherwise.

The viscosity, which is referred to here as bubble viscosity, was determined at 25 ° C. using a Gardner-Holdt bubble viscosity tube according to ASTM D-1545-76 and is referred to here in seconds, bubble seconds or as bubble viscosity.

The viscosity, expressed in Pas, is determined using a Brookfield viscometer, Model RVF. The measurements were made when the resole was at 25 ° C and a spindle was chosen to get a reading near the middle range of 20 revolutions per minute. A number 5 spindle was used for most readings (ASTM D-2196).

The pH of the resol was measured using a Fisher Accument pH Meter, Model 610 A. The pH probe was adjusted to 4.0.7.0 and 10.0 with pH standards before each use (ASTM E-70).

The phenol content in the resol was determined by infrared spectroscopy. Infrared determination was carried out using a recorder infrared spectrophotometer with sodium chloride optics (Perkin Elmer Model No. 21), sealed liquid absorption cells and a 0.1 mm sodium chloride window. The method was to measure the infrared absorption of an acetone solution of the phenolic resol at 14.40 µm. The phenol content of the resole sample was determined by comparing the absorption of the sample with the absorption of standard solutions with known phenol contents, which were measured under identical conditions. This method proved to be reproducible up to a phenol content of + 0.14%.

The free formaldehyde content in the phenolic resole was determined by the hydroxylamine hydrochloride method. The general method is to dissolve the resole sample in methanol, adjust the pH to the bromophenol blue transition point, and add excess hydroxylamine hydrochloride. The reaction releases hydrochloric acid, which is titrated with a standard sodium hydroxide solution in order to obtain the same bromophenol-blue transition point.

A resole sample is first weighed to 0.1 mg (generally a sample of 1-3 grams) in a 150 ml beaker containing 10 ml of methanol. The mixture is stirred until the resol has completely dissolved. The weight of the resole sample should be such that more than 1/1 of the hydroxylamine hydrochloride is complete after the reaction. After the resol has been dissolved in methanol, 10 ml of distilled water and 10 drops of bromophenol blue indicator are added. The pH of the sample solution is adjusted by adding 0.5 N sodium hydroxide or 0.5 N sulfuric acid dropwise until the indicator changes to blue. Then 25 ml of hydroxylamine hydrochloride solution (ACS grade) are pipetted into the beaker and the reaction is allowed to proceed at room temperature for 15 minutes. Then the solution is quickly titrated with 0.5 N sodium hydroxide solution according to the blue color to which the sample solution has previously been adjusted. The sample solution is stirred magnetically during the titration and the stirring speed is very high when the transition point is reached. At the same time, the same procedure is carried out with an empty sample, all components except the resol sample being used. The free formaldehyde of the sample is then calculated as follows:

o / r • c m u j (V, -V2) x N x 3.001

% free formaldehyde = —-

W

wherein

Vi is the volume of the 0.5 N sodium hydroxide solution in ml used to titrate the sample, and

V2 is the volume of the 0.5 N sodium hydroxide solution in ml used to titrate the blank sample.

N is the normality of the sodium hydroxide solution,

W is the weight of the resol sample in grams.

The number 3.001 is a constant to convert the gram equivalent weight of the formaldehyde in percent.

Further details of this method are given in Kline, G.M., "Analytical Chemistry of Polymers", High Polymers, Volume II, Part 1, Interscience Publishers, Inc. (1959).

The water content of the resols was determined using the Karl Fischer method, and modified to determine the end point of the titration electrometrically. The device used was an automatic Karl Fischer titrator, Aquatest II from Photovolt Corp., the device being assembled, filled and electrically connected in accordance with the manufacturer's operating instructions. A suitable sample of the resol, as shown in the table below, was weighed into a clean, dry volumetric bottle. 20 to 50 ml of dry pyridine or methanol are added to the bottle, the bottle is closed and the solution is stirred thoroughly until the resol sample has completely dissolved. The solution is made up to the respective volume with dry pyrite

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Diluted din or methanol, the bottle is sealed with a cuff type rubber stopper and then shaken to mix the solution.

Table of the determined sample size

Resole weight (g) final volume of water (wt .-%)

Sample solution (ml)

3-4 50 0.3-5

2-3 100 5-15

1-2 100 16-25

1 100> 25

Using a suitable dry syringe and needle, draw 1 to 2 ml of the sample to be examined into the syringe and empty into a waste container. This rinsing is repeated a few times. The sample is then drawn into the syringe until the volume is slightly above the desired calibration mark, after which it is adjusted to the desired mark. The syringe needle is cleaned with a paper towel and the needle is inserted through the sample access septum until it is below the surface of the titration solution. The sample is then injected into the titration solution and the syringe is quickly withdrawn. The automatic titration is carried out and the results are recorded,

when the titration is finished. In the same way as described above, the water content of the empty sample is determined. The weight percentage of water is calculated as follows:

(Ci — C2) -

Water content (wt.%) - w x ^

wherein

Ci is the number read off, which represents the total amount of water in the analysis sample,

C2 the number read, which represents the total nm amount of water in the blank,

V2 the volume to which the dissolved sample has been diluted, in ml,

Vi is the volume of the titrated sample in ml and W is the weight of the resol sample in g.

Further details of this procedure can be found in Mitchell, J.Sr. and Smith, D.M., Aquametry, Chemical Analysis Series, Volume 5, Interscience Publishers Inc. (1948).

The weight average molecular weight, the number average molecular weight and the polydispersibility of the resols were determined by gel permeation chromatography. The instrument used was a Waters Associates, Inc. gel permeation chromatograph that had five columns arranged in series (each column was 30.48 cm long) filled with Styragel. The pore size of the Styragel showed the following sequence: 1 column 1000 "10 m, 2 columns 500" 10 m, 2 columns 100 ~ "10 m. The determination was made by the differential refractive index (differential refractometer R401 from Waters) System was operated with tetrahydrofuran (THF) as solvent and at a flow rate of 2 ml / min. The resole sample, which weighs about 220 to 250 mg, was dissolved in 25 ml of THF. In order to prevent deviations due to solvent evaporation, the solutions transferred with the least possible contact with air and weighed in closed flasks. The GPC was calibrated by using monodispersed polymer

Stryrene was used as the standard polymer against which the resol was measured. The calibration was carried out at room temperature using THF as a solution; carried out for polystyrene. The results of the GPC were recorded and recorded using a Waters Associates data recorder (730 Data Module), which performed all calculations and printed out the final results of the analysis. Further details on the mode of operation are described in the literature by Waters. Compare also Waters publication No. 82475 with the title "GPC, Data Reduction & the 730-150 C Combination" and Waters Technical Brief No. 102, "HPLC Column Performance Rating".

The core samples without top layers were used to measure the k-factors according to the revised standard ASTM C 518.

The following examples serve to further explain the invention. Parts and percentages are by weight unless otherwise specified.

Preparation 1

A phenol formaldehyde resol with a molar ratio of formaldehyde to phenol of 2: 1 was produced in the laboratory in a 4 liter reactor equipped with a reflux condenser, a thermocouple for reading the temperature in ° C, a feed funnel, an air stirrer with a two-bladed propeller and a device was provided for heating (jacket) and cooling (ice bath) of the reactor. First, 1434 g of 90% phenol (13.73 mol) was weighed out and added to the reactor. Then 1207 g of flaky 91% para-formaldehyde (36.61 mol) was weighed out and added to the reactor. This phenol formaldehyde mixture was stirred while heating to 78 ° C. In the meantime, a 45% aqueous KOH solution was prepared. Then 35.53 g of the 45% KOH solution (0.285 mol) was added to 478.4 g of the 90% phenol (4.58 mol) and mixed thoroughly. The KOH-phenol mixture was then added to the feed funnel. After the reactor temperature reached 78 ° C, the KOH phenol solution was added dropwise over a period of 150 minutes. During this addition period, the temperature of the reactor was adjusted to 78-80 ° C by heating and / or cooling the reactor. During the early stage of the addition, it was necessary to cool the reactor occasionally to keep the exothermic reaction under control. Also, a light gel was formed during the early stage, which disappeared during the addition period. Particular attention was paid to temperature when the gel was present, since heat transfer through a gel is slow.

After all of the phenol-KOH mixture had been added, the reaction mixture was heated to 85 to 88 ° C and held at this temperature. The bubble viscosity measurements were made at a temperature of 25 ° C in a Gardner-Holdt bubble viscosity tube (ASTM D-1545-76) with samples of the reaction mixture taken every 30 minutes after the temperature was 85 to 88 ° C had achieved. When a bubble viscosity of about 15 seconds was reached, the reaction mixture was gradually cooled (about 15 minutes) to a temperature of about 68 to 79 ° C. When this temperature was reached, it was maintained and further bubble viscosity measurements were made every 30 minutes until a bubble of about 30 seconds was obtained. The bubble viscosities were then determined every 15 minutes until the bubble viscosity was approximately 60 seconds. At a bubble viscosity of 60 seconds

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14.57 g of 90% formic acid solution (0.285 mol) was added to the reactor and the reaction mixture was cooled to 55 ° C. When the reactor temperature had reached 55 ° C, 190 g of "Morflex" 1129 (dimethyl isophthalate) were added and dissolved. The reaction mixture was then transferred to a storage container and stored in a refrigerator until use. The resol obtained had a Brookfield viscosity of 6600 * 10 -3 Pas at 25 ° C. The resol contained 1.9% free phenol, 3.6% free formaldehyde and 17.3% water. The weight average molecular weight was 981, the number average molecular weight 507 and the polydispersibility 1.93.

Preparation 2

A phenol formaldehyde resol with a 2: 1 molar ratio of formaldehyde to phenol was produced on an industrial scale in a 3785 liter reactor equipped with a reflux condenser, a thermocouple for temperature reading in ° C, a device for accurate chemical supply, a device for stirring the mixture and one Device for heating and cooling the reaction mixture was provided.

First, 1726.21 kg of 90% phenol (16 542.3 mol) was added to the reactor. Then 1453.08 kg of flaky 91% para-formaldehyde (44,101.78 mol) was added to the reactor with stirring. The phenol formal dehyde mixture was stirred, heating to 78 ° C and maintaining this temperature for about 2 hours.

In the meantime, a solution of KOH and phenol was prepared in a mixing tank by carefully adding 576.71 kg of 90% phenol (5514.14 mol) and 42.84 kg of 45% KOH solution (343.92 mol) were mixed.

After 2 hours and at a reactor exit temperature of 78 ° C, the KOH-phenol solution was added to the reactor at a rate of 3.401 to 5.11 liters per minute over a period of 2l / z hours. During this addition period, the temperature of the reactor was adjusted to 78-92 ° C by heating and / or cooling the reactor or temporarily stopping the phenol-KOH addition.

After all of the phenol-KOH mixture had been added, the reaction mixture was heated to 85 to 88 ° C and held at this temperature. The bubble viscosity measurement was carried out at a temperature of 25 ° C with a Gardner-Holdt bubble viscosity tube (ASTM D-1546-76) with samples of the reaction mixture which, after the temperature had reached 85 to 88 ° C, every 30 Minutes have been removed. When the bubble viscosity was about 15 seconds, the reaction mixture was gradually cooled to a temperature of about 68 to 79 ° C. When this temperature was reached, the bubble viscosities were again determined every 15 minutes until a bubble of about 30 seconds was obtained. The bubble viscosity. were then determined every 15 minutes until a bubble of about 60 seconds was obtained. At a bubble viscosity of 60 seconds, 17.56 kg of a 90% formic acid solution (343.90 mol) was added to the reactor and the reaction mixture was cooled to 55 ° C. When the reaction mixture had reached 55 ° C., 106.7 kg of "Morflex" 1129 were added and dissolved. The reaction mixture was then transferred to a storage tank and kept refrigerated until used. The resol obtained had a Brookfield viscosity of 7,400 Pas at 25 ° C. The resol contained 3.2% free phenol, 3.5% free formaldehyde and 14.6% water. The resole had a weight average molecular weight of 1222, a number average molecular weight of 550 and a polydispersity of 2.22.

Preparation 3

A phenol formaldehyde resol with a molar ratio of formaldehyde to phenol of 2: 1 was produced in the laboratory according to a preferred method, using a 4 liter reactor which was equipped with a reflux condenser, a thermocouple for temperature reading in ° C, an addition funnel and an air stirrer a double-blade propeller and a device for heating (jacket) and cooling (ice bath) of the reactor was provided. 2550 g of 90% phenol (24.4 mol) were initially weighed out and added to the reactor. Then 45.6 g of 45% KOH solution (0.366 mol) were weighed out and added to the reactor. This phenol-catalyst mixture was stirred while being heated to 78 ° C. In the meantime, 1610 g of 91% para-formaldehyde flakes (48.8 mol) were weighed out. When the reactor has reached a temperature of 78 ° C, the para-formaldehyde flakes (161.0 g) are added to the reactor. This stepwise addition of the para-formaldehyde is carried out in a total of 10 steps at intervals of 10 minutes each with essentially the same amounts. The temperature is maintained at 78 to 82 ° C during the addition period.

After all of the formaldehyde had been added, the reaction mixture was heated to 85 to 88 ° C and held at this temperature. The bubble viscosities were carried out at a temperature of 25 ° C with a Gardner-Holdt bubble viscosity tube (ASTM D-1545-76) with samples of the reaction mixture taken every 30 minutes after the temperature reached 85-88 ° C. When the bubble viscosity is about 15 seconds, the reaction mixture is gradually cooled (about 15 minutes) to a temperature of 78 ° C. When this temperature was reached, the bubble viscosities were again determined every 15 minutes until a bubble of about 60 seconds was obtained. At a bubble viscosity of 60 seconds, 18.7 g of a 90% formic acid solution (0.366 mol) was added to the reactor and the reaction mixture was cooled to 65 ° C. When the reaction temperature reached 65 ° C, 190 g "Morflex" 1129 (dimethyl isophthalate) was added and dissolved. The reaction mixture was then transferred to a storage container and stored in a refrigerator until further use. The resol formed had a Brookfield viscosity of 6000 * 10 3 Pas at 25 ° C. The resol contained 2.3% free phenol, 3.4% free formaldehyde and 17.5 g water. The resole had a weight average molecular weight of 902, a number average molecular weight of 448 and a polydispersity of 2.01.

Preparation 4

A phenol formaldehyde resol with a 2: 1 molar ratio of formaldehyde to phenol was produced on an industrial scale according to a preferred method using a 22 710 liter reactor equipped with a reflux condenser, a thermocouple for temperature reading in ° C, a device for accurate Chemical addition, a device for stirring the mixture and a device for heating and cooling the reaction mixture was provided.

First, 13,755 kg of 90% phenol (131,700.8 moles) were added to the reactor. Then 256.3 kg of 45% KOH solution (2055.8 mol) were added to the reactor with stirring. The mixture was stirred while warming to 78 ° C.

In the meantime, 8701 kg of 91% para-formaldehyde flakes (263,942.7 mol) were weighed out.

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When the reactor reached a temperature of 78 ° C, the para-formaldehyde flakes were metered into the reactor at a substantially uniform rate over a period of 3 hours. During the addition period, the reactor temperature was adjusted to 78 to 82 ° C.

After all of the para-formaldehyde had been added, the reaction mixture was heated to 85-88 ° C and held at this temperature. The bubble viscosities were carried out at a temperature of 25 ° C with a Gardner-Holdt bubble viscosity tube (ASTM D-1576-76) with samples of the reaction mixture taken every 30 minutes after the temperature reached 85-88 ° C. When the bubble viscosity was about 15 seconds, the reaction mixture was cooled to a temperature of about 78 ° C. When this temperature was reached, it was maintained, again determining the bubble viscosities every 15 minutes until a bubble of about 45 seconds was reached. The mixture was then cooled to a temperature of 68 to 70 ° C. and the bubble viscosities were then determined every 15 minutes until a bubble of about 60 seconds was reached. At a bubble viscosity of 60 seconds, 94.8 kg of 90% formic acid solution (1854.8 mol) was added to the reactor and the reaction mixture was cooled to 55 ° C. While the reaction mixture was cooled to 55 ° C., 958.9 kg of “Morflex” 1129 were added and dissolved. The reaction mixture was then transferred to a storage tank and kept cool until further use. The resol obtained had a Brookfield viscosity of 8700-10 "3 Pas at 25 ° C. The resol contained 3.7% free phenol, 2.92% free formaldehyde and 15.6% water. The resol had a weight-average molecular weight of 1480, a number average molecular weight of 582 and a polydispersity of 2.55.

Preparation 5

A phenolic resole with a molar ratio of formaldehyde to phenol of 2: 1 was prepared in the laboratory in accordance with preparation 3, except that the reaction was ended, the pH was adjusted, "Morflex" 1129 was added and the resol solution was cooled when a bubble viscosity of 10 seconds was reached.

The resol obtained had a Brookfield viscosity of 850 * 10 -3 Pas at 25 ° C. The resole contained 4.1% free phenol, 4.9% free formaldehyde and 14.0% water. The resole had a weight average molecular weight of 519, a number average molecular weight of 400 and a polydispersity of 1.26.

Preparation 6

A phenol formaldehyde resol with a molar ratio of formaldehyde to phenol of 2: 1 was produced in the laboratory in a 4 liter reactor equipped as described in preparations 1 and 3. 2550 g of 90% phenol (24.4 mol) were initially weighed out and added to the reactor. Then 1610 g of 91% para-formaldehyde were weighed out and added to the reactor. The phenol formaldehyde mixture was stirred and warmed to 70 ° C. In the meantime, while the phenol formaldehyde mixture was being heated, a 45% KOH solution was prepared. When the temperature reached 70 ° C, '/ ó was added to the KOH solution (7.6 g, 0.061 mol). After 10 minutes another sixth of the KOH solution was added. The rest of the KOH solution was added in the same manner, with the reaction mixture warming to reflux conditions and under reflux 30

Minutes. The reaction mixture was then cooled to 78 ° C and reacted at this temperature until a bubble viscosity of 80 seconds was reached. The pH was then adjusted by adding 18.7 g (0.336 mol) of a 90% formic acid. The phenolic resole solution was then cooled to 65 ° C and 190 g of Morflex was added and the solution was further cooled to 55 ° C. The resol solution was then transferred to a storage container and stored under cooling until further use.

The resol obtained had a Brookfield viscosity at 25 ° C of 7500-10-3 Pas. The resole contained 2.4% phenol, 3.2% formaldehyde and 15.8% water. The resole had a weight average molecular weight of 1055, a number average molecular weight of 534 and a polydispersity of 1.98.

Preparation 7 A phenol formaldehyde resol with a 2: 1 molar ratio of formaldehyde to phenol was made in the laboratory using the device and general procedure described in Preparations 1 and 3, but with the following changes.

First, 1434 g of 90% phenol (13.73 mol) was added to the 4 liter reactor. Then 1207 g of 91% para-formaldehyde flakes (36.31 mol) were added to the reactor. This phenol formaldehyde mixture was stirred and heated to 78 ° C. In the meantime, a 45% KOH solution was prepared and 35.53 g of this 45% KOH solution (0.285 mol) was added to 478 g 90% phenol (4.58 mol) and the KOH Phenol mixture was mixed. The KOH-phenol mixture was then added to the addition funnel. When the phenol-formaldehyde mixture reached a temperature of 78 ° C, the KOH-phenol mixture was added dropwise over 150 minutes. The remaining reaction was carried out according to preparation 3.

The phenolic resole had a Brookfield viscosity of 6000'10-3 Pas at 25 ° C. The resole contained 3.2% phenol, 3.2% formaldehyde and 15.1% water. The resole had a weight average molecular weight of 1156, a number average molecular weight of 543 and a polydispersity of 2.13.

Preparation 8 A phenol formaldehyde resole was performed in the laboratory according to the procedure described in Preparation 3, except that the molar ratio of formaldehyde to phenol was 1.6: 1.

The phenolic resole obtained had a Brookfield viscosity of 6200 "10 -3 Pas at 25 ° C. The resol contained 1.5% formaldehyde, 3.7% phenol and 16% water. The resole had a weight average molecular weight of 1248 , a number average molecular weight of 532.6 and a polydispersity of 2.36.

Preparation 9 A phenol formaldehyde resole was prepared in the laboratory according to the procedure described in preparation 3, but the molar ratio of formaldehyde to phenol was 2.4: 1.

The phenolic resole obtained had a Brookfield viscosity of 6400 * 10 -3 Pas at 25 ° C. The resol contained 6.7% formaldehyde, 1.5% phenol and 18.8% water. The phenol had a weight average molecular weight of 1030, a number average molecular weight of 561 and a polydispersity of 1.85.

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Preparation 10 A phenol formaldehyde resole was performed in the laboratory using the procedure described for Resole No. III in U.S. Patents 4,176,106 and 4,176,216 from column 29, line 15.

The phenolic resole obtained contained 7.3% formaldehyde, 5.6% phenol and 7.9% water. The resole had a weight average molecular weight of 688, a number average molecular weight of 440 and a polydispersity of 1.56.

Preparation 11 A phenol formaldehyde resol was prepared after preparation 10. After the resole was made, the water content was adjusted to 16%. The resol was then heated to 68 to 70 ° C and this temperature was maintained until a bubble viscosity of 80 seconds was reached.

The resol obtained contained 5.4% formaldehyde, 2.3% phenol and 14.8% water. The resole had a weight average molecular weight of 882, a number average molecular weight of 515.8 and a polydispersity of 1.71.

Preparation 12 A phenolic resole was made according to Example 17 of U.S. Patent 3,953,645.

The resol obtained had 1.7% formaldehyde, 8.8% phenol and 10.8% water. The phenolic resole had a weight average molecular weight of 2295, a number average molecular weight of 590 and a polydispersity of 3.89.

example 1

A phenolic foam was made in the laboratory using a laboratory mold as shown in Figures 1A and 1B. The mold was made from 1.27 cm thick aluminum bars for the sides and 0.64 cm thick aluminum plates for the top and bottom and had internal dimensions of 23.8 l x 33.02 x 5.08 cm. The dimensions of the shape can be changed, for example by 3.81 cm or 7.62 cm wide bars instead of the 5.08 cm sides.

The mold was coated with a mold release agent and preheated in a 66 ° C oven. A dry piece of corrugated cardboard of approximately 23.81 cm was dried in an oven heated to 66 ° C for 10-15 minutes. With the mold and cardboard in the oven, the foamable phenolic resin composition was prepared as follows. First, 10 parts (33.2 g) of a fluorocarbon foaming agent from a 50/50 part by weight mixture of "Freon" ll / "Freon" 113 (trichloromonofluoromethane / 1,1,2-trichloro-1,2,2-trifluoroethane ) premixed with a high speed air mixer (3000 rpm) with a portion (3.3 g) of a silicone surfactant (Union Carbide L-7003). The fluorocarbon foaming agent mixture was then placed in an ice bath and cooled to 10-19 ° C. Then 76.6 parts (254.3 g) of an aqueous phenolic resole prepared in accordance with Preparation 1 were mixed with the high speed air mixer with 2.4 parts (8.0 g) of the silicone surfactant L-7003. The fluorocarbon foaming agent / surfactant premix was then mixed with the phenolic resole / surfactant premix. This mixture of phenolic resole, foaming agent and surfactant was then cooled to 10 to 13 ° C in an ice bath. Then 10 parts (33.2 g) of one

Mixture of anhydrous toluenesulfonic acid and anhydrous xylene sulfonic acid (Ultra-TX acid from Witco Chemical) weighed in a syringe and cooled to 4.4 to 7.2 C. The cardboard and mold were then removed from the oven. The anhydrous arylsulfonic acid catalyst was then mixed with the mixture of the phenolic resole, the foaming agent and the surfactant at a high speed for 10 to 15 seconds. Then 210 g of the final foamable phenolic resole composition was immediately poured onto the S-shaped plate as shown in Figure 1B. The cardboard was then folded over the top of the foamable mixture and immediately placed in the mold. The mold was closed with all clamps brought in place and tightened. The mold with the foamable composition was then placed in an oven heated to 66 ° C for 4 minutes. After removal from the oven, the foam was removed from the mold and weighed. The foam was left to stand for 24 hours before samples were cut to determine foam properties.

The cured foam contained 100% closed cells, measured using an air pycnometer according to ASTM D-2856-70, and had a density of approximately 52 kg / cm 3. The foam had an initial k value of 0.135 prior to equilibrium. The SEM of the foam is shown in Figure 6. The SEM shows that the cell walls of the foam have essentially no perforations, perforations or cracks and that the cell walls are thick.

The k values of the foam after aging are given in Table I and also illustrate that the phenolic foam includes the foaming agent and permanently retains the foaming agent. The cell walls are accordingly thick and have essentially no openings, perforations or cracks.

Table I

Old k value

10 days 0.123

30 days 0.122

90 days 0.113

120 days 0.113

280 days 0.118

Example 2

A phenolic resole batch was prepared by mixing 74.6 parts of the phenolic resole prepared in Preparation 2 with 2.4 parts of a silicone surfactant L-7003.

An anhydrous toluenesulfonic acid / xylenesulfonic acid mixture (Ultra-TX catalyst from Witco Chemical) was used as the catalyst.

The added phenolic resole composition, the catalyst and an added fluorocarbon foaming agent containing 6 parts 1, 1, 2-trichlor-1, 2,2-trifluoroethane, 6 parts trichloromonofluoromethane and 1 part L-7003 surfactant silicone agent , were added separately and mixed in a distribution device of the phenolic foam installation, as is shown schematically in FIG. 2.

The added phenolic resole composition, the catalyst and the added foaming agent composition were at a temperature of 9.4 to 12.2 ° C, 0.5 to 8.2 ° C and - 3 to +1.1 ° C before Mixing kept in the distribution facility.

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The foamable composition was continuously applied at a temperature of about 30 ° C for 6 hours on a lower cover layer made of an aluminum-coated cardboard, which is moved with the lower conveyor.

An upper cover layer made of the same material and side papers made of polyethylene-coated kraft paper were fed to the system immediately before the curing recesses, as shown in FIGS. 2 and 3.

The relative amounts of the resol, catalyst and foaming agent added in the foamable composition are measured 8 times within a total of 6 hours and are shown in the table below.

Table!!

No.

Total time elapsed

Parts of added * resol

Parts

catalyst

Parts of added foaming agent

1.

15 minutes

76

12.8

11.2

2nd

45 min

76

13.0

11.0

3rd

61 min

76

13.0

11.0

4th

101 min

76

13.8

10.2

5.

170 min

76

13.6

10.4

6.

255 min

76

13.8

10.2

7.

315 min

76

13.8

10.2

8th.

360 min

76

13.8 '

10.2

The foamable composition was applied to the bottom liner material, the speed of the conveyor being adjusted so that when the foam expanded to substantially fill the curing recess, further expansion was prevented and pressure was generated within the curing recess.

A pressure measurement, which was carried out in the curing recess every 30 minutes during the experiment approximately at a 3/4 distance from the inlet of the curing recess, showed a pressure which the foam in the recess generated from 27 600 to 48 400 Pa. Temperature measurements of the foam immediately after exiting the curing recess were carried out 4 times during the test, the temperatures being between 72 and 82 ° C.

Samples of the foam product were taken every hour. The starting k values, the k values after aging and the core densities of the foam samples are given in Table III. Figure 7 is a scanning electron microphotograph (SEM) of the phenolic foam made according to this example. The SEM clearly shows that the cell walls are essentially free of perforations, perforations and cracks. This is also confirmed by the k-value data according to Table III:

Table III

Sample No.

Output

k value after

Core density

k value

45 days kg / m3

1

0.161

0.118

4,233

2nd

0.158

0.114

4,154

3rd

0.164

0.115

4,508

4th

0.160

0.114

4,197

5

0.171

0.115

4,598

6

0.168

0.121

4,598

Sample # 1 was checked after a period of one year and was found to still have a k-value of 0.118.

Comparative Example 1

A phenolic foam was made in the laboratory on a small scale as follows.

First, 10 parts (33.2 g) of a fluorocarbon foaming agent from a 50/50 parts by weight mixture of "Freon" ll / "Freon" 113 (trichloromonofhiprmethane / l, l, 2-trichloro-l, 2,2-trifluoroethane ) premixed with a high-speed air stirrer (3000 revolutions per minute) with a part (3.3 g) of a surface-active silicone agent (Union Carbide L-7003). The fluorocarbon foaming agent mixture was placed in an ice bath and cooled to 10 to 13 ° C. Then 221 g of the phenolic resole prepared according to preparation 1 were mixed with 2.4 parts (8.0 g) of the surface-active silicone agent L-7003 in a tin can using the high-speed air stirrer. The fluorocarbon foaming agent / surfactant premix was then mixed with the phenolic resole / surfactant premix. This mixture of phenolic resole, foaming agent and surface-active agent was cooled to 10 to 13 ° C. in an ice bath. Then 66 g of a catalyst mixture of phenolsulfonic acid and methanesulfonic acid in a weight ratio of 5/3, which contained 33% by weight of water, were weighed out in a beaker and cooled to 4.4 to 7.2 ° C. The acid catalyst was then canned with the mixture of phenolic resole, foaming agent and surfactant at a high speed for 10-15 seconds. The can with the foamable composition was then placed in an oven heated to 66 ° C for four minutes. After removal from the oven, the foam was left to stand for 24 hours before cutting samples to determine foam properties. The foam of this example is shown in Figure 8.

The SEM clearly shows that the cell walls have numerous perforations. Furthermore, the SEM illustrates the need to produce the phenolic foam in a substantially closed form that is capable of doing so due to the foaming composition. withstand the pressure exerted since most of the cell walls of the foam are broken. The starting k value of this foam was 0.22, which also shows that the cell walls were broken and / or contained perforations since no fluorocarbon was retained in the foam.

Example 3

A phenolic foam was made in a laboratory using a laboratory mold as shown in Figures 1A and 1B. The shape consisted of 1.27 cm thick aluminum bars on the sides and 0.64 cm thick aluminum plates on the top and bottom and had internal dimensions of 23.81 x 33.02 x 5.08 cm.

The mold was coated with a mold release agent and was preheated in an oven heated to 66 ° C. A piece of dry corrugated cardboard measuring 23.81 x 71.12 cm was dried in an oven heated to 66 ° C for 10 to 15 minutes. While the mold and corrugated board were in the oven, the foamable phenolic resin composition was made as follows. First, 10 parts (33.2 g) of a 50/50 parts by weight mixture of "Freon" ll / "Freon" 113 (trichloromonofluoromethane / 1,1,2-trichloro-l, 2,2-trifluoroethane) were used as foaming agents at high speed - Air stirrer (3000 revolutions per minute) premixed with a part (3.3 g) of a surface-active silicone agent (Union Carbide L-5340). This fluorocarbon foaming agent mixture was placed in an ice bath and cooled to 10 to 13 ° C. Then 71.6

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Parts (237.8 g) of the aqueous phenolic resol according to Preparation 3 were mixed with the high-speed air stirrer with 2.4 parts (8.0 g) of the surface-active silicone agent L-5340 and three parts (10 g) of urea. The premix of the fluorocarbon foaming agent and the surfactant was then mixed with the premix of the phenolic resole and the surfactant. This mixture of phenolic resole, foaming agent and surfactant was cooled to 10 to 13 ° C in an ice bath. Then 12 parts (39.8 g) of an anhydrous aryl sulfonic acid containing 65% by weight of toluenesulfonic acid and 35% by weight of xylene sulfonic acid were weighed out with a syringe and cooled to 4.4 to 7.2 ° C. The cardboard and mold were then removed from the oven. The mixture of anhydrous toluene / xylene sulfonic acid was then mixed with the mixture of phenolic resole, foaming agent and surface-active agent at a high number of turns for 10 to 15 seconds. Then 210 g of the final foamable phenolic resole composition was immediately poured onto the S-shaped cardboard as shown in Figure 1B. The cardboard was folded over the top of the foamable mixture and immediately placed in the mold. The mold was closed with all clamps brought in place and tightened. The mold with the foamable composition was placed in a 66 ° C oven for four minutes. After removal from the oven, the foam was removed from the mold and weighed. The foam was left to stand for 24 hours before samples were cut to determine foam properties.

The cured foam contained 100% closed cells, measured using an air pynometer according to the test standard ASTM D-2856-70, and had a density of approximately 52 kg / cm 3. The foam had an initial k value of 0.14 before equilibrium. The SEM of this foam is shown in Figure 9. The SEM clearly shows that the cell walls are thick and have no openings, cracks or perforations. This is also evident from the k-value data, which show that the fluorocarbon foaming agent is trapped in the cells.

The k values of the foam after aging are shown in the table below and show that the foaming agent is included in the foam.

Old k value

10 days 0.117

30 days 0.117

60 days 0.118

90 days 0.114

150 days 0.117

Example 4 •

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole that was used was the phenolic resole that was made after Preparation 4.

The SEM of this foam is shown in Figure 10. The SEM shows that the cell walls have no cracks, perforations or perforations. The starting k value of this foam was 0.120.

Comparative Example 2

A phenolic foam was made according to the procedure outlined in Example 3, except that the phenolic resole used was Preparation 5 phenolic resole.

The SEM of this foam is shown in Figure 11. The SEM shows that some of the cell walls are broken and some of the cell walls are thin and cracked. This example illustrates the need for a resol with the molecular weight properties defined above. The foam had an initial k value of 0.22.

Example 5

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole that was used was the phenolic resole of Preparation 6.

The SEM of this foam is shown in Figure 12. The SEM shows that the cell walls have essentially no cracks, perforations and perforations. The foam had an initial k value of 0.138 and a k value after 90 days of 0.138.

Example 6

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole used was the phenolic resole of Preparation 7.

The SEM of this foam is shown in Figure 13. The SEM shows that the cell walls did not contain any cracks, breakthroughs and perforations. The foam had a k value of 0.118 after 180 days, which clearly shows that the foaming agent was included in the foam.

Comparative Example 3

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole used was the phenolic resole of Preparation 8.

The SEM of this foam is shown in Figure 14. The SEM shows that numerous cell walls were broken or thin and torn. The foam had an initial k value of 0.22.

Comparative Example 4

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole used was the phenolic resole of Preparation 9.

The SEM of this foam is shown in Figure 15. The SEM shows numerous broken cell walls. The foam had an initial k value of 0.26 and a k value after 30 days of 0.224.

Comparative Example 5

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole used was the phenolic resole of Preparation 10.

The SEM of this foam is shown in Figure 16. SEM shows that numerous cell walls had broken open, although a closed form was used.

This illustrates the need to use a resole with molecular weights and dispersity as defined above to obtain a foam that has no perforations, even if a closed shape is used. This foam has an initial k value of 0.22.

Example 6

A phenolic foam was made according to the procedure described in Example 3, except that

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the phenolic resole used was preparation 11 phenolic resole.

The SEM of this foam is shown in Figure 17. The SEM shows that the cell walls have no cracks, breakthroughs and perforations. The foam has an initial k value of 0.127 and a k value after 30 days of 0.118. This example shows that the process of resol production is not important as long as the required molecular weights and the required polydispersibility are obtained.

Comparative Example 6

A phenolic foam was made according to the procedure described in Example 3, except that the phenolic resole used was the phenolic resole of Preparation 12.

The SEM of this foam is shown in Figure 18. The SEM shows that most of the cell walls have broken open. The foam had an initial k value of 0.25. This example illustrates the need to use a primary phenol in the manufacture of the phenol formaldehyde resol.

Example 7

A phenolic resole was prepared according to Preparation 2, except that the reaction was stopped when a bubble viscosity of 80 seconds was reached. This resole had 15.1% water, 3.1% formaldehyde and 3.2% phenol. The resole had a weight average molecular weight of 1504, a number average molecular weight of 591 and a polydispersity of 2.55.

The foam was made from this resole according to the procedure described in Example 3.

The SEM of this foam is shown in Figure 19. The SEM shows that all cell walls have no cracks, openings or perforations. This example illustrates that it is desirable to use the preferred resoles. This foam has an initial k value of 0.121.

Comparative Example 7

A phenolic foam is made in the laboratory using a laboratory mold as shown in Figures 1A and 1B. The shape is made from 1.27 cm thick aluminum bars for the sides and 0.64 cm thick aluminum plates for the top and bottom and has internal dimensions of 23.81 x 33.02 x 5.08 cm. The phenolic resole used in this example is a commercially available phenolic resole from Georgia Pacific, which is sold under the name GP-X-2014/945. This resol is obtained with a water content of 7%. A further 5% by weight of water was added to obtain a resol with a water content of 12% by weight. This resin had a weight average molecular weight of 674, a number average molecular weight of 398.5 and a polydispersity of 1.69. The mold was coated with a mold release agent and preheated in an oven heated to 66 ° C. A piece of dry corrugated cardboard measuring approximately 23.81 x 71.12 cm was dried in an oven heated to 66 ° C for 10-15 minutes. While the mold and cardboard were being dried in the oven, the foamable phenolic resin composition was prepared as follows. First, 10 parts (33.2 g) of a 50/50 by weight mixture of "Freon" ll / "Freon" 113 (trichloromonofluoromethane / l, l, 2-trichloro-l, 2,2-trifluoroethane) were used as fluorocarbon Foaming agent premixed with a high speed air stirrer (3000 rpm) with a portion (3.3 g) of a surface active silicone agent (Union Carbide L-7003). The fluorocarbon foaming agent mixture was placed in an ice bath and cooled to 10 to 13 ° C. Then 76.6 parts (254.3 g) of the phenolic resole was mixed with the high speed air stirrer with 2.4 parts (8.0 g) of the silicone surfactant L-7003. The fluorocarbon foaming agent and surfactant premix was then mixed with the phenolic sol and surfactant premix. This mixture of phenol resol, foaming agent and surface-active agent is cooled to 10 to 13 ° C. in an ice bath. Then 10 parts of an anhydrous mixture of toluenesulfone / xylenesulfonic acid (Ultra-TX acid from Witco Chemical) are weighed out in a syringe and cooled to 4.4 to 7.2 ° C. The cardboard and mold are then removed from the oven. The anhydrous arylsulfonic acid catalyst is then mixed with the mixture of phenolic resole, foaming agent and surface-active agent with a high number of turns for 10 to 15 seconds. Then 210 g of the final foamable phenolic resole composition is immediately poured onto the S-shaped cardboard as shown in Figure 1B. The cardboard is folded over the top of the foamable mixture and the whole thing is immediately placed in the mold. The form is closed, with all clamps being brought in place and tightened. The mold with the foamable composition is placed in an oven heated to 66 ° C for four minutes. After removal from the oven, the foam is removed from the mold and weighed. The foam is left to stand for 24 hours before samples are cut to determine foam properties. The foam has a k-value of 0.22. A scanning electron microphotograph of this phenolic foam is shown in Figure 20. The SEM shows that the foam has cell walls that have essentially no perforations. However, SEM also shows that numerous cell walls are broken or very thin and cracked. This example illustrates the need to use resols that have a higher molecular weight in accordance with the invention.

Comparative Example 8

A phenolic foam was made according to Comparative Example 1, except that the resole was made according to Preparation 4 and there was a ratio of the ingredients according to Example 4.

The SEM of this foam is shown in 200 times magnification in FIG. 21 and in 400 times magnification in FIG. 22. Figures 21 and 22 show that the cell walls are broken. This example demonstrates the need for a substantially closed shape to prevent cell wall breakthrough. A comparison of this SEM with the other SEM, in particular FIGS. 11, 16 and 20, likewise shows the difference in breakdown caused by the lack of back pressure and breakdown caused by a resol that is too reactive when pressure is applied.

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Claims (7)

662577 1. A foamable composition comprising phenol formaldehyde resoles, which comprises at least one aqueous phenol formaldehyde resole, a surfactant, a foaming agent and an acid catalyst, characterized in that the phenol formaldehyde resole has a molar ratio of the formaldehyde to the phenol of 1.75: 1 to 2.25: 1 , has a weight average molecular weight of more than 800, a number average molecular weight of more than 350 and a polydispersity of more than 1.7, the content of free formaldehyde and free phenol each being up to 7 percent by weight. 2. Composition according to claim 1, characterized in that the weight average molecular weight of the phenol formaldehyde resol is 950 to 1500. 2nd PATENT CLAIMS 3. Composition according to claim 1 or 2, characterized in that the number average molecular weight of the phenol formaldehyde resol is 400 to 600. 4. Composition according to one of the claims 1 to 3, characterized in that the polydispersity of the phenol formaldehyde resol is 1.8 to 2.6. 5. Composition according to one of claims 1 to 4, characterized in that the content of free formaldehyde and free phenol is in each case less than 4 percent by weight. 6. Composition according to one of claims 1 to 5, characterized in that the phenol formaldehyde resol has a molar ratio of the formaldehyde to the phenol of 2: 1. 7. Use of the composition according to one of claims 1 to 6 for the production of a phenolic foam, in which the composition is foamed and cured in a substantially closed form. 8. Phenolic foam made according to claim 7.