JPS6053060B2 - Manufacturing method for panels based on polycondensation resins - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing panels based on polycondensable resins.

In particular, the invention relates to the manufacture of panels from phenolic resins containing fillers such as spherical expanded polystyrene or expanded clay, glass microspheres or similar materials. Panels obtained by mixing fillers with liquid mixtures containing phenolic resins and their curing agents have several drawbacks with currently used methods.

These difficulties arise from the construction of the panels and from the fact that their manufacture cannot be adequately controlled. One of the above-mentioned difficulties is that under the manufacturing conditions currently employed to obtain open-celled phenolic resins, water seepage into the resin and air trapped within the resin can cause the resin to burn. It's easy.

Furthermore, this open-celled resin has poor cohesive strength. The above-mentioned disadvantages can be alleviated by sandwiching the resulting panels between suitable facings, such as steel facings.

However, since the panels themselves have poor cohesion, only surface materials that form a cohesive casing around the panels can be used. In particular, it is not possible to produce a facing material in the form of a polymerizable resin layer that is integral with the panel over its entire surface. Therefore, the applications of panels based on phenolic resins are currently limited. Another drawback of the above panels is their lack of homogeneity.

That is, since the density of the filler is smaller than the density of the resin, the filler tends to float, especially in the foaming stage, before the resin is completely polycondensed, whereas a resin with a high density tends to settle. Cutting panels manufactured using currently employed methods shows that the filler is much more concentrated at the top of the panel than at the bottom. the result,
The top of the panel is extremely weak. Furthermore, the resin foams quite unevenly. That is, foaming occurs much more freely at the top of the panel than at the bottom, resulting in lower mechanical strength at the top of the panel. Furthermore, when used industrially according to currently known formulations using spherical polystyrene and phenolic resins, there is a drawback that the shelf life, that is, the period from preparation to use, is short; The amount of resin that can be prepared for use in manufacturing is severely limited.

The object of the present invention is to overcome the above-mentioned difficulties by appropriately selecting the composition of the polycondensable mixture and by controlling the manufacturing conditions, especially the temperature during the manufacturing process.

The method of manufacturing a panel made of a foamed phenolic resin having a closed cell structure and covering a filler according to the present invention is as follows:
a) a filler such as a liquid mixture comprising at least one phenolic resin, a curing agent, a surfactant, and a pore-forming agent having a boiling point below the polycondensation temperature of the mixture and above the ambient temperature at the time of mixing; (b) placing the mixture in a mold leaving a space in the mold for continued foaming of the mixture; and (C) increasing the temperature of the mixture until it reaches near the boiling point of the pore-forming agent. (d) holding the mixture temperature substantially constant for a period sufficient to achieve maximum foaming of the mixture, and (e) further increasing the temperature of the maximally foamed mixture progressively to its polycondensation temperature. It is characterized by

In the present invention, maximum foaming can be obtained before curing by separately performing the foaming of the mixture and its polycondensation (i.e., curing).

That is, prior to curing, the resin mixture completely fills the mold used in manufacturing, resulting in a panel with closed cells, an impermeable skin, and a uniform appearance.
If the polycondensable material based on reinforced phenolic resin is placed in the mold beforehand to form the surface layer after polycondensation, maximum foaming is achieved in the mold and the foamed phenolic resin is The surface layer and the core penetrate into each other at the boundary. As a result, the surface layer has good adhesion to the core made of phenolic foam, and good cohesive strength is obtained due to the closed cell structure. This separation of the foaming stage and the curing stage is made possible by selecting an appropriate pore-forming agent.

The pore-forming agent used has a boiling point below the polycondensation temperature of the reaction mixture but well above ambient temperature. The use of such pore-forming agents prevents the initiation of foaming of the emulsion during the mixing process, thereby avoiding bottoming out the shelf life of the mixture and not restricting the subsequent foaming of the mixture. After introducing the polycondensable mixture and the filler into the mold, the mold is heated so that foaming and polycondensation of the resin occur separately. Such heating allows the reaction to be controlled and a homogeneous product to be obtained. Once the filler particles are coated with the required amount of resin, foaming of the resin occurs around each particle, creating a pressing force acting in all directions around each particle in the mold. According to the invention, heating is actually carried out as follows. That is, the temperature is gradually increased until near the boiling point of the pore former, and then the temperature is held constant for a sufficient period of time to achieve maximum foaming of the mixture under the high vapor pressure of the pore former. The temperature is then raised to the polycondensation temperature and polycondensation is carried out at maximum foaming in a limited volume mold. The temperature is preferably raised gradually from the foaming temperature, ie, a temperature close to the boiling point of the pore-forming agent, to the polycondensation temperature, and if necessary, combined with reduced pressure, to more completely remove water vapor and formaldehyde vapor. This progressive heating and complete removal of steam results in panels with improved appearance when building panels with an optionally reinforced skin coating layer of phenolic resin. The composition of the polycondensable mixture is chosen in such a way that a homogeneous coating layer is formed around the filler, ie, the maximum amount of the resin mixture is homogeneously deposited on the filler.

Maximum foaming is thus achieved and polycondensation as described above is possible. To this end, the amount of surfactant in the resin mixture is increased in order to improve the adhesion of the resin to the filler particles. The amount of curing agent is reduced so that polycondensation does not occur at the same time during the foaming stage. The essential purpose of setting the composition and proportions of the resin mixture is to impart an appropriate viscosity to the mixture before foaming and to maintain this viscosity during the foaming process. This appropriate viscosity is one that exhibits sufficient adhesion to the filler and that does not cause an excessive amount of the resin mixture to aggregate around the filler and cause non-uniform foaming due to gravity. To tell. To give one example, in the case of closed cell forming phenolic resin, conventionally 10-
15% by weight of curing agent is added whereas for the above purpose about 5% by weight is added.

The amount of surfactant used is conventionally about 1%, but this increases to about 2% for the above purpose. Further, the pore-forming agent is conventionally used in an amount of 5-15% by weight, but this amount is increased to about 2% by weight. The above percentages are all percentages by weight based on the weight of the phenolic resin. Good results can be obtained depending on the above-mentioned usage amounts. The method according to the invention comprises a liquid mixture comprising at least one phenolic resin, a curing agent, a surfactant and a pore-forming agent having a boiling point above the ambient temperature during the mixing process and below the polycondensation temperature of the mixture. It is characterized in that it is mixed with a filler.

After all of the above ingredients are filled into the internal space of the closed mold, leaving room for continued foaming and expansion, the temperature of the contents is gradually increased to near the boiling point of the pore-forming agent, and the temperature of the contents is increased to a maximum level. It is also a feature of the process of the present invention to maintain a substantially constant temperature for a period sufficient to achieve foaming and then gradually increase the temperature of the contents to a temperature at which polycondensation occurs. The resin mixture is maintained in a gel state until a temperature near but below the boiling point of the pore forming agent is reached such that a maximum amount of resin mixture is maintained around the filler before and during foaming. Another feature is the viscosity.
The panel obtained by the present invention is characterized in that in the panel made of a phenolic resin covering filler particles, the phenolic resin is a foamed phenolic resin having a closed cell structure.

Hereinafter, specific examples of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a partially cutaway perspective view of a panel obtained by the present invention.

2-4 are diagrams for explaining the manufacturing process of the panel according to the present invention, and show cross sections cut along a vertical plane perpendicular to the substantially horizontal plane of the mold.

These drawings show the various components of the finished panel (Figures 1 and 4) and the various components during the panel manufacturing stage (Figures 2 and 4).
and FIG. 3) are all designated by the same reference numerals.

In the embodiment shown in FIG. 1, the panel obtained according to the invention has a skin layer 1 consisting of a polycondensable phenolic resin, preferably reinforced with, for example, glass fiber fabric or other similar reinforcement.

The outer skin layer 1 is integrally bonded to the entire surface of the core made of foamed phenolic resin having a closed cell structure. The expanded phenolic resin 2 covers the filler, for example spheres or microspheres of expanded material such as glass or expanded polystyrene, expanded clay, etc. The filler 3 is embedded in the resin 2, including the side of the core in contact with the skin layer 1, and the resin 2 forms an impermeable skin. The coating layer 1, which forms an impermeable skin, gives the panel watertightness and mechanical surface resistance, as well as a uniform appearance to the panels according to the invention and thus produced. However, the panel according to the invention may also lack such a covering layer 1. To produce such a panel, the filler 3 is mixed with the mixture to form the resin after foaming and polycondensation.

The mixture comprises at least one phenolic resin, a curing agent, a surfactant and a pore forming agent and is initially a liquid. A specific example of a mixture that gives good results is 5% by weight curing agent consisting of sulfuric acid plus alcohol and water, 2% by weight surfactant consisting of silicone oil and trichlorotrichloride, based on the weight of the phenolic resin in the mixture. Contains 2% by volume of a porogen consisting of fluoroethane.

Trichlorotrifluoroethane has a boiling point of about 4 rc, which is intermediate between the ambient temperature in the mixing stage and the polycondensation temperature of the mixture.

The polycondensation temperature is approximately 6σC at 0.6 atmospheres. Selection of such a pore-forming agent is one of the requirements of the present invention, and by controlling the temperature rise of the mixture placed in the mold, it is possible to achieve maximum foaming before polycondensation. become.
After mixing the filler and resin, the mixture is placed in one mold half 4 of the mold 5 so as to obtain a good distribution of the filler.

To obtain a panel with a phenolic resin coating layer 1 of the same type as the core, before placing the resin mixture in the mold halves 4,
Preferably glass fiber. A layer of phenolic resin containing reinforcing material, such as a layer, has been formed on the inner surface of mold half 4 and the other mold half 6. This manufacturing step is shown in FIG. The phenolic resin layer 1, optionally containing reinforcing agents, is preferably in the state of a prepolymerized gel before the resin mixture 2-3 is introduced into the mold halves of the mold 5;

Next, mold 5 is formed by folding half mold 6 over half mold 4.
Seal it tightly.

Since the resin mixture 2-3 is initially placed only in the half mold 4, there is a free space 7 above the resin mixture 2-3 in the closed mold 5.
This space 7 is connected to a vacuum pump 8. When heating before and during polycondensation (indicated by arrow 9 in FIG. 3) a vacuum pump 8 can be used to create a reduced pressure in the space. Although it is sufficient to reduce the pressure slightly in the temperature raising stage and the foaming stage, the pressure should be greatly reduced in the condensation stage in order to remove the above-mentioned components. In the present invention, heating is performed in three stages. In the first step, the temperature of the mold and its contents is gradually increased from ambient temperature to, for example, about 40C (i.e., near the boiling point of the pore-forming agent used) over, for example, three millings. urge Next, the temperature is maintained near the boiling point (for example, 40'C) for, for example, 30 minutes, during which time the mixture is foamed by high-pressure steam generated from the pore-forming agent. Polycondensation then takes place at the end of the foaming stage when the temperature is gradually increased from 40°C to 60'C. For example, the polycondensation temperature is maintained at about 12 mm. If the polycondensation is carried out at about 60°C, expanded polystyrene particles can be used as filler 3, but in this case the temperature should not be heated above 80'C.

Maximum foaming can be achieved prior to curing by applying heat to the compositions described above under the conditions described above.
That is, the entire interior space of the mold 5 is filled with foamed material, which is pressed against the covering layer 1, and furthermore, at the end of the foaming stage and before the curing stage, the surface covering layer 1 is pressed against the inner wall of the mold ( (See Figure 4). Furthermore, the filler 3 is evenly distributed within the panel. The composition and manufacturing conditions described above are merely examples, and they can of course be modified in various ways without departing from the scope of the present invention.

The compositions described above have a long shelf life and lend themselves to mass production.

This resin mixture can be used for about 1 or 2 days.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a panel obtained by the present invention. Figures 2, 3 and 4 are all diagrams for explaining the manufacturing process of the panel according to the present invention, and show cross sections cut along a vertical plane perpendicular to the substantially horizontal plane of the mold. . 1
...Outer skin layer, 2...Foamed phenolic resin, 3...Filler, 4...Half mold, 5...
...Mold, 6...Half mold, 7...Free space, 8...Vacuum pump.

Claims (1)

[Scope of Claims] 1 (a) at least one phenolic resin, a curing agent,
mixing a filler with a liquid mixture comprising a surfactant and a pore-forming agent having a boiling point below the polycondensation temperature of the mixture and above the ambient temperature at the time of mixing; (b) the mixture is subsequently capable of foaming; (c) gradually increasing the temperature of the mixture until it reaches near the boiling point of the pore-forming agent; and (d) achieving maximum foaming of the mixture. and (e) gradually increasing the temperature of the maximally foamed mixture to its polycondensation temperature. A method for manufacturing a panel made of foamed phenolic resin. 2. Have a composition suitable to maintain the mixture in a gel state until a substantially constant temperature is reached, such that the viscosity is suitable to maintain a maximum amount of the mixture around the filler before and during foaming. A method according to claim 1. 3. A method according to claim 1 or 2, characterized in that a reduced pressure is generated in the free space in the mold before and during the polycondensation, at least during the heating stage. 4. A method according to any one of claims 1 to 3, in which a phenolic resin layer in a gel state is adhered to the inner wall surface of the mold before the filler and the mixture are put into the mold. the method of. 5. The method according to any one of claims 1 to 4, wherein the foaming mixture is gradually heated from the boiling point of the pore-forming agent to the polycondensation temperature. 6. The method according to any one of claims 1 to 5, wherein the pore-forming agent is trichlorotrifluoroethane. 7. The method according to any of claims 1 to 6, wherein the amount of curing agent used is about 5% by weight based on the weight of the resin. 8 The amount of surfactant used is approximately 2% by weight based on the weight of the resin.
The method according to any one of claims 1 to 7. 9. A method according to any one of claims 1 to 8, wherein the amount of pore-forming agent used is about 20% by weight based on the weight of the resin.