DE2856717A1 - TABLE OF PHENOLIC RESIN AND METHOD FOR PRODUCING IT - Google Patents

Description

DIPLOMA INGEN »EI

HELMUT LAMPRECHT

PATENT ADVOCATE 2 8 5 6 "" Π 7

. if.

CORNELIUSSTR. 42 D-8000 MÜNCHEN 5-TEL. 089/24 O7 75 ■ TELEX 5 28 425

2654

STRATIFORME s.a.

26, Route Nationale Oersee (North)
France

Phenolic resin board and process for its manufacture

The invention relates to a board made of a phenolic resin enveloping a filler material and a method for its production.

In particular, the invention relates to the manufacture of panels based on a polycondensable resin, namely one Phenolic resin, which is foamed with filler material in the form of balls Polystyrene or expanded clay or microspheres or glass or similar material is provided.

These panels, which are obtained by making the filler material mixed with a liquid mixture that contains phenolic resin and a hardener for this resin, show at their

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POi..SCHECK ACCOUNT MUNICH OSO 4 5 -806 (B LZ 700 1 OO SO) ORIGINAL INSPECTED

DEUTSCHE BANK MUNICH. P RO M E f. AD E SPACE, ACCOUNT NO. 19/30 694 CSLZ 700 700 10} TELEGRAMS / CABLES LAWCLAIMS MUNICH

Stratiform SA - / - 2654

current manufacture has a number of disadvantages that relate to their structure and that one has their Manufacturing poorly mastered.

One of these disadvantages is that under the conditions under which the production is currently carried out, a Phenolic resin with open cells is obtained in which foreign matter, in particular can store water and that, on the other hand, this material is easily combustible due to the enclosed air is. In addition, this open cell resin lacks cohesion.

It is possible to reduce these disadvantages by placing the panel obtained between panels of a suitable type, for example between steel panels, but only panels that form a shell around the panel, which is a suitable one, come into consideration Has cohesion because the board itself lacks cohesion. In particular, it is not possible to shape these diaphragms to produce a coating of polymerizable resin which is firmly bonded to the panel over its entire surface, this restriction restricts the use of the currently known panels based on phenolic resin.

Another disadvantage of these panels is that they lack homogeneity. The fillers with opposite the density of the lower density resin tend to rise when that Resin is not fully polycondensed and especially during the foaming phase, while the denser resin tends to to descend. A section through a panel produced by the currently known method shows a much greater density of the

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Filler material in the upper than in the lower section of the panel, with with the result that the board is more fragile in the upper portion. It is also found that the resin in of a heterogeneous type foams, i.e. it expands or foams much more freely towards the upper portion of the board than towards the lower section, which also degrades the mechanical properties of the panel in the upper section.

Moreover, there are also difficulties in the industrial one Processing of polystyrene beads and phenolic resins their currently known association. Their short service life in the casting vessel or the like, i.e. their short potential Time after preparation considerably limits the amount of resin that can be prepared and, consequently, for one Manufacturing process can be over-used.

The present invention allows these disadvantages to be eliminated altogether, at the same time by suitable selection of the Composition of the polycondensable mixture to be used and by controlling the conditions, in particular the Temperature development during manufacture.

By separating the foaming of the mixture and its polycondensation, i.e. their cure, the invention enables maximum expansion before curing, i. a complete filling of the mold, in which the production is carried out, before the hardening of the mixture, with the result that closed cells and an impermeable

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outer skin, as well as a homogeneous design can be achieved. If you look at the inner surfaces of the foam to be foamed beforehand In particular, a polycondensable and optionally reinforced material based on phenolic resin is attached has, which is suitable to form a screen-like coating after the polycondensation, it allows this possibility the maximum foaming of a limited volume, good penetration of the diaphragm-like coating and the Foamed phenolic resin sheet core in their adjacent one another To obtain boundary layers, resulting in good adhesion of the cover to the phenolic foam core, which also has good cohesion due to the structure of the closed cells.

This separation of the foaming phase and the hardening phase is obtained due to an expedient choice of the pore former, its boiling point below the polycondensation temperature the mixture, but is still significantly higher than the ambient temperature, in order to during the mixing or kneading process To prevent the start of emulsification, which on the one hand reduce the life of the prepared mixture and on the other hand would limit the later ability of the mixture to foam. The way in which the mold is heated after the polycondensable mixture and the fillers is adapted according to the invention so that the separation of the foaming phase of the Resin and the polycondensation phase is effectively achieved in order to control the reaction and to obtain a homogeneous material. When the beads have been enveloped with the necessary amount of resin, one is placed in the area of each bead

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AufschaUming of the resin, which is in the form by pressure is noticeable in all directions and this in the area of each bead. According to the invention one actually causes the Heating in such a way that the temperature increases progressively up to a temperature which is in the range of the boiling temperature of the pore former, whereupon this temperature is kept practically constant for a period of time which is sufficient is to achieve the maximum foaming of the mixture under an increased vapor pressure of the pore former. Afterward the temperature is increased again progressively up to the polycondensation temperature in order to carry out this polycondensation, when the foaming has reached its maximum value, taking into account the limited volume of the mold, in which it takes place. This increase in temperature starting from the temperature level of the foaming phase, i.e. starting from from the temperature adjacent to the boiling point of the pore former to the polycondensation temperature takes place after a preferred embodiment in a progressive manner to allow that water vapor and formol vapor are particularly completely removed under the combined effect of the vacuum. These progressive and thereby particularly complete removal allows an improved surface shape in the case obtained, in which a panel is produced which has a screen for the outer cladding, which can also be made from optionally reinforced phenolic resin.

The composition of the polycondensable mixture is moreover chosen so that a homogeneous coating of the fillers is guaranteed, i.e. a maximum of the mixture in more homogeneous

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Way to attach these fillers before the maximum foaming and then in the manner described above the polycondensation takes place.

To this end, the ratio of surface-active substances is increased Agent in the mixture to allow better adhesion of the resin to the beads. One reduces the proportion of Hardener to reduce the effects that could initiate the polycondensation phase that occurs simultaneously with the foaming phase could take place and this at the selected temperature level. The main purpose of these changes in the mixing ratio compared to known mixing ratios in raising the viscosity to a value before foaming and to maintain it during foaming, which is sufficiently high to ensure sufficient bonding with the fillers and which, on the other hand, is sufficiently low to avoid excessive agglomeration of the mixture around the fillers, which the result could be that the foaming takes place incorrectly for reasons of weight or does not occur at all.

Without intending to be limiting and only as an example, it should be noted here that good results are obtained if the hardening agent in the polycondensable mixture is reduced to a value in the order of 5%, compared to a value in the order of 10 to 15%. in the case of currently known compositions for the manufacture of closed cell phenolic resin, if the level of surfactants is kept around 2 % , which in known compositions is of the order of 1 % , and if

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the proportion of pore-forming agents, which is usually of the order of 5 to 15%, is increased to 20 % in order to improve the foamability of the mixture, these percentages being expressed as percentages by weight based on the unit weight of the phenolic resin.

As follows from the foregoing, the invention exists to solve the problem that in the panel made of a filling material enveloping phenolic resin Phenolic resin is a foamed closed cell phenolic resin.

In addition, the invention for the production of such a panel consists of a method in which the filler material with a liquid mixture is mixed, the at least one phenolic resin, a hardener, a wetting agent, and a pore former which is selected so that it has a boiling point which is below the polycondensation temperature of the mixture and above the ambient temperature during the mixing process.

If you put the mixture in the interior of a closed mold in an amount that leaves room for in the mold the later foaming of the mixture keeps free, a further advantageous embodiment of the invention consists in that one the temperature of the mixture increases progressively up to a temperature in the range of the boiling point of the pore former, that the temperature is then substantially maintained for a period of time sufficient to allow the mixture to foam up to the maximum

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keeps constant, and that the temperature of the mixture is increased again progressively to the maximum polycondensation to induce foamed mixture.

Another advantageous embodiment of the invention is that the mixture is composed such that it is in a gel-like state until this constant temperature is reached, in order to give the mixture such a To give viscosity that it collects in maximum quantity around the fillers before and during foaming.

On the basis of the following description of an embodiment of the invention shown in the drawing, this will be explained in more detail.

It shows:

Fig. 1 is a perspective, partially broken away partial view of a panel according to the invention,

Fig. 2 shows a cross section through an open mold for manufacture the board after pouring the mixture,

Fig. 3 shows a section corresponding to FIG. 2 through the closed form in a subsequent process step and

4 shows a section through the closed mold in a further method step.

These figures are used to identify the finished panel and the same reference numerals have been used to identify these various components during the various stages of panel manufacture.

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In the embodiment shown in Fig. 1, the panel has this an outer facing or an outer coating 1 made of polycondensed phenolic resin, which is preferably for example by a Fiberglass mat or other appropriate reinforcement is reinforced and over its entire surface with the one from one with closed cell foamed phenolic resin existing core 2 is firmly connected, which in turn fillers 3 for example in the form of beads or microbeads made of glass or a foamed material such as expanded polystyrene, expanded clay, etc. ^ surrounds.

The fillers 3 are enveloped by the resin 2, including the contact area between the core and the cladding 1 where the resin 2 forms an impermeable skin.

The board according to the invention can also be shown without the cover 1, because this impermeable skin prevents the board from being leakproof and ensures its mechanical surface strength and, moreover, offers a homogeneous appearance when the panel according to the invention has been made.

To make such a table ^ one mixes or kneads the fillers 3 with the mixture which forms the resin 2 after foaming and polycondensation, this mixture is likewise identified in FIGS. 2 to 4 by the reference number 2.

This initially liquid mixture comprises at least one phenolic resin, a hardener, a wetting agent and a pore former.

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Merely by way of example and without the intention of limiting it, it should be noted that good results are obtained if a mixture is used which contains 5 % of a hardener consisting of sulfuric acid with the addition of alcohol and water, 2% of a wetting agent consisting of silicone oil and 20% % of a pore former consisting of a trichlorotrifluoroethane, these ratios referring to the mass per unit weight of the phenolic resin in the mixture.

The trichlorotrifluoroethane has a boiling point in the range of 47 C, which is between the ambient temperature during mixing and the polycondensation temperature "the Mixture is, which is in the order of 60 C at a pressure of 0.6 bar. This selection is located in accordance with one of the features of the invention, according to which the maximum expansion or foaming before the polycondensation takes place by controlling the temperature increase of the mixture when it is in the mold.

After mixing with the fillers to distribute them as well as possible, the mixture is divided into one of the halves 4 introduced a mold 5, optionally after the inner surfaces of this mold half 4 and the other mold half has painted with a coating of phenolic resin, in which preferably a reinforcing material such as a Glass fiber cloth is embedded, if you want to get a board, the outside of which has a phenolic coating 1 of the same Nature like that of the core. This process step for producing the panel is shown in FIG.

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The optionally reinforced phenolic resin coating is preferably located 1 in a gel-like state before polymerization when the mixture 2 to 3 is poured into the half 4 of the mold 5 will.

The mold 5 is then hermetically sealed in that the mold half 6 is pressed onto the mold half 4, whereupon The volume 7 remains free above the mixture 2 to 3 inside the mold 5 closed in this way, because initially only the mold half 4 was filled with the mixture 2 to 3. A vacuum pump 8 is then connected, which at least during the through the arrows 9 in Fig. 3 indicated heating before the polycondensation following this heating process a negative pressure generated. The negative pressure can occur during the temperature increase phase and stay low during the foaming process, he but is increased during the polycondensation phase to remove vapors.

According to the invention, the heating takes place in three phases first with a duration of 30 minutes, for example, the temperature of the mold and its contents progressively from the Ambient temperature increased to a temperature of, for example, of the order of 40 C, i.e. to a temperature which is close to the boiling point of the pore former used. The temperature is then set to this value of, for example 40 C held for a period of, for example, 30 minutes, during which phase the mixture is foamed under the increased vapor pressure by the pore former. At the end of this foaming phase, the temperature is

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progressively increased from 40 C to 60 C, at which temperature the polycondensation takes place. This final heating process takes about 120 minutes, for example.

A polycondensation temperature of the order of 60 ° C allows 3 beads of expanded polystyrene as a filler to be used, which must not be heated above 80 C.

The heating of the mixture under the above-mentioned conditions allows maximum foaming before the To obtain curing, at the end of the foaming phase and before curing, as shown schematically in Fig. 4, the the entire interior of the mold 5 is filled by the foamed material which is in contact with the surface envelope 1 under pressure, which in turn presses against the wall of the mold. In addition, a homogeneous distribution of the filler materials 3 is obtained inside the board.

The mixture obtained by the composition described has a sufficiently long-lasting workability that a large amount of the mixture can be prepared, the mixture being workable for up to one to two days remain.

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Claims (14)

28b-SV'7 Stratiforme S.A. 2654 claims: 1. Panel made of a phenolic resin enveloping a filler material, characterized in that the phenolic resin is a foamed Closed cell phenolic resin (2). 2. Panel according to claim 1, characterized in that it has an impermeable phenolic skin on its surface. 3. Panel according to one of the preceding claims, characterized characterized in that it has an outer coating (1) based on a polycondensed phenolic resin. 4. Board according to one of the preceding claims, characterized in that the filling material (3) consists of balls or microspheres consists of a material which consists of glass and foamed materials such as polystyrene or expanded clay is selected. 5. A method for producing a board according to any one of the preceding claims, characterized in that the filler material is mixed with a liquid mixture, the at least one phenolic resin, a hardener, a wetting agent and a pore former which is selected to have a boiling temperature 9 0 9 8 2 9/0621 ORIGINAL INSPECTED 28567 ^ 7 Stratiforme S.A. - 2 - 2654 which is below the polycondensation temperature of the mixture and is above the ambient temperature during the mixing process. 6. A method of making a panel according to claim 5, wherein the mixture is in the interior of a closed mold is introduced in an amount which leaves space in the mold for later foaming of the mixture, characterized in that, that the temperature of the mixture is gradually increased up to a temperature in the range of the boiling point of the pore former, that the temperature is then maintained for a period of time sufficient for maximum foaming of the mixture keeps essentially constant, and that the temperature of the mixture is again increased progressively to the polycondensation the maximum foamed mixture. 7. The method according to claim 6, characterized in that the mixture is so composed that it is in a gel-like state until this constant temperature is reached is located in order to give the mixture such a viscosity that it is in before and during foaming maximum quantity to collect the fillers. 8. The method according to any one of claims 6 or 7, characterized in that that a negative pressure is generated in the mold during the heating before and during the polycondensation. 9. The method according to any one of claims 6 to 8, characterized in that that you turn the mold before filling in the 903829/0621 ORIGINAL INSPECTED Stratiforme S.A. - 3 - 2654 Filler material and the mixture in this form with a coating coated with gelled phenolic resin. 10. The method according to any one of claims 5 to 9, characterized in, that during the polycondensation phase one of the boiling point of the pore former to the polycondensation temperature progressive heating takes place. 11. The method according to any one of claims 5 to 10, characterized in that the pore former is a trichlorotrifluoroethane is. 12. The method according to any one of the preceding claims, characterized in that the proportion of the hardener used a value of 5% of the amount of resin is reduced. 13. The method according to any one of claims 5 to 12, characterized in that the proportion of the wetting agent is increased to 2 % compared to the amount of resin. 14. The method according to any one of claims 5 to 13, characterized in that the proportion of the pore former is increased to 20 % . 909829/0621