JPH0379382B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field This invention relates to a method for producing a foamed phenolic resin composite. More specifically, the present invention relates to a method for producing a foamed phenolic resin composite with improved flexural modulus and surface hardness. (b) Conventional technology Conventionally, foamable powders have been produced by mixing lightweight aggregate particles such as plastic foamed (or unfoamed) particles and inorganic particles with uncured novolac type phenol-formaldehyde resin, curing agent, and blowing agent. A known method is to produce a phenol-foam composite by mixing the mixture with a phenol resin composition, filling a predetermined mold with the mixture, and heating and foaming the mixture to harden it. (c) Problems to be solved by the invention However, in such a manufacturing method, no matter how uniformly the aggregate particles and the expandable phenolic resin composition are mixed before foaming and curing, the aggregate particles It has been difficult to obtain a phenol foam complex in which phenol foam is uniformly dispersed. This is because the balance between the bone particles and the composition before foaming and hardening may be disrupted due to foaming and expansion of the composition during foaming and hardening, and the balance between the aggregate particles and the composition may change during or after filling into the mold. This is thought to be due to natural non-uniformity due to differences in specific gravity and shape. This tendency was particularly strong when aggregate particles with a particle size of 2 mm or more were used, and the larger the particle size, the more pronounced it became. Regarding this point, the present inventors first formed a layer of the foamable phenolic resin composition only on the bottom surface of the mold, and then loaded aggregate particles on the composition layer without mixing the composition with the foamable phenolic resin composition. proposed a method for producing a phenol foam composite in which aggregate particles are uniformly dispersed by heating (Japanese Patent Application Laid-Open No. 1989-1999).
Publication No. 101031). However, when producing a phenol foam composite with a thickness of 20 mm or more using this method, it was difficult to obtain one whose upper surface was completely filled with phenol foam. Therefore, such composites have extremely low flexural modulus and are unsatisfactory as products. Furthermore, if a phenol foam composite with a thickness of 20 mm or less is manufactured by this method, a large amount of foamable phenolic resin composition is required to completely fill the phenol foam up to the upper surface, which increases the cost. Also, a method of manufacturing a phenol foam composite by coating aggregate particles with a foamable phenolic resin composition, filling the foamable resin-coated particles into a mold, and then heating the mold with the mold closed. has also been proposed. In the phenol foam composite produced by this method, pearlite grains are uniformly dispersed throughout, and the density of the phenol foam portion is uniform. However, such a composite has an insufficient flexural modulus because the density inside and outside of the phenol foam portion is the same. Furthermore, if the amount of the foamable phenolic resin composition was small, only a phenol foam composite with a soft surface could be obtained. Furthermore, since a step of coating the aggregate particles with the expandable phenolic resin composition is required, there is a problem in that the manufacturing cost is high. The present invention was made in view of the above situation, and specifically aims to provide a manufacturing method that can easily and inexpensively manufacture a foamed phenolic resin composite having a high flexural modulus and high surface hardness. be. (d) Means and effects for solving the problems Thus, according to the present invention, a granular foamable phenolic resin composition comprising a phenolic resin initial condensate, a separated foaming agent, and a curing agent added as necessary. into a mold to form a granular layer of the composition at the bottom thereof, and then (a) loading aggregate particles onto the granular layer without substantially mixing them with the granular layer; repeating the steps of forming an aggregate particle layer and (b) again dispersing the expandable phenolic resin composition onto the aggregate particle layer to form a granular layer of the composition one to multiple times; A composite layer was formed with a granular layer of an expandable phenolic resin composition on the bottom and an upper part, with an aggregate particle layer having an expandable phenolic resin composition layer optionally interposed therebetween, and then the mold was closed. A method for producing a foamed phenolic resin composite is proposed, which is characterized by foaming and curing a foamable phenolic resin composition by heating the foamed phenolic resin composition. Examples of the phenolic resin initial condensate used in this invention include novolac type and resol type phenolic resin initial condensates. Here, the novolak-type phenolic resin initial condensate is a so-called novolak-type phenolic resin known in the art that is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst. means that polymerization can proceed further. This resin is generally solid at room temperature. On the other hand, the resol-type phenolic resin initial condensate is a so-called resol-type phenolic resin known in the art, which is obtained by reacting phenols and excess aldehydes in the presence of a basic catalyst, and is acid-cured. It means a substance that can undergo polymerization by using an agent and heating. Such resol-type phenolic resin itself is a liquid containing about 20% reaction water, but
This is further dehydrated (water is evaporated) to form a solid product (containing about 1% water), and then this solid product is crushed or cut by extrusion to obtain the granular resol type phenolic resin used in the present invention. Of course, a commercially available powdered resol type phenolic resin may also be used.
Incidentally, in this invention, granules include not only powder but also relatively small-diameter pellets, tablets, flakes, and primary foam particles. The above phenols include, in addition to phenol,
3,5-xylenol, m-cresol, 2,5
-xylenol, 3,4-xylenol, 2,4
-xylenol, o-cresol, p-cresol, etc. The aldehydes include formaldehyde, paraformaldehyde, hexamethylenetetramine, furfural, acetaldehyde, acetals, and the like. A preferred initial condensate for use in this invention is a condensate of phenol and formaldehyde. The term "separable blowing agent" in the present invention refers to inorganic and organic blowing agents that can separate and generate gas during heat curing in a composition mixed with a phenolic resin initial condensate. Typical examples of these are N,
Organic blowing agents such as N′-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, azobisisobutyronitrile, azodicarbonamide, paratoluenesulfonyl hydrazide, as well as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and ammonium nitrite. ,
Examples include inorganic decomposition type blowing agents such as azide compounds (eg CaN ₆ ). All of these are in powder form. The amount of the blowing agent to be added is the required amount mainly taking into consideration the density of the desired final foam, but it is appropriate to be 1 to 50 parts by weight per 100 parts by weight of the phenolic resin initial condensate; ~25 parts by weight is preferred. Hardeners are used in particular when novolak-type phenolic resin precondensates are used. This curing agent means a compound that can be decomposed by heating and can undergo a crosslinking reaction with the novolak type phenolic resin initial condensate.
Such a compound is a compound used to form a phenolic resin by reacting with phenols, similar to formaldehyde, and is usually in powder form. Specific examples include hexamethylenetetramine, paraformaldehyde, methylal, dioxolane, trioxane, tetraoxane, trimethylolphosphine, S-triazine, and the like. The amount of the curing agent added is generally 1 to 30 parts by weight, preferably 4 to 15 parts by weight, per 100 parts by weight of the novolak type phenolic resin. Note that the foamable phenolic resin composition of the present invention may contain small amounts of other various additives, such as fillers such as clay. The amount of these additives is preferably 100 parts by weight or less based on 100 parts by weight of the phenolic resin. The aggregate particles used in this invention include organic or inorganic particles or mixtures thereof, but preferably those that do not react with the expandable phenolic resin composition. Examples of inorganic materials include perlite, shirasu balloons, glass balloons, foamed glass particles, fine glass particles, rock wool particles, slag, foamed clay particles, sand, gypsum particles, and metallic particles. Examples of organic substances include synthetic resin particles and foamed particles thereof, wood powder particles, paper particles, etc., but usually 100
Resins having heat resistance of .degree. C. or higher are preferred, and examples thereof include resol type phenolic resin foam beads, styrene-maleic anhydride copolymer resin foam beads, and polypropylene foam beads. There is no particular limitation on the shape of the aggregate particles, and they may be spherical, crushed fragments, or irregularly shaped.
Particle size ranges from microscopic particles with a particle size of 1 mm to particle sizes of 40 to 50.
Any grain size up to mm is fine. The density of the aggregate particles is not particularly limited; when considering the use of lightweight foam molded products, it is sufficient to select one with a density of 1 g/cm ³ or less, even if the aggregate is of high density. good. The filling rate of the aggregate particles in the mold is 100% to 10%, preferably 100% to 30%. In this invention, first, the above-described foamable phenolic resin composition is introduced into the bottom of a mold such as a metal mold so as to form a substantially uniform layer. This introduction should be adjusted to give a layer of as uniform thickness as possible. This process is shown in FIG. In the figure, 1 indicates a granular layer of a foamable phenolic resin composition, 2 indicates a mold, and 3 indicates a release paper. Instead of the release paper 3, a suitable surface material may be used for integration. The desired aggregate particles 5 are then deposited on the granular layer 1.
is loaded and filled into the cavity 4. At this time, it is necessary to stack the aggregate particles 5 and the granular composition so that they do not mix as much as possible.
In addition, the filling rate of aggregate particles varies from 100% to 10 depending on the purpose.
You can change it up to %. This process is as shown in FIG. After filling the composition layer 1 with aggregate particles 5 in a separated layer state, as shown in FIG. After the layer 1' is formed almost uniformly, a release paper 3' and a suitable surface material are placed on it, an upper mold 6 is set, the mold is closed, and heating is performed. Heating may be carried out at a temperature that allows the composition itself to foam and harden, usually at 120 to 180°C for 3 to 20°C.
It takes about minutes. By such heating, the granular compositions at the bottom and top of the mold undergo a melting process and harden while foaming. At this time, they gradually expand upward and downward, respectively, and the aggregate particles 5 stacked on the mold harden. It fills the cavity as it expands through the individual voids. Then, a foamed phenolic resin composite 7 of the present invention shown in FIG. 5 in which each aggregate particle is bonded and integrated with a phenolic resin foam layer is formed in a mold. In some cases, as shown in FIG. 4, a granular layer (intermediate layer) 8 of a foamable phenolic resin composition may be further interposed within the aggregate particle layer. If the amount of granular layers formed on the bottom and top portions is insufficient in terms of the thickness and density of the intended foamed phenolic resin composite, it is suitable to form such an intermediate layer in advance, and It is also possible to have more layers. At this time, the step (a) and the step
A multilayer structure may be obtained by repeating (b) in a predetermined manner. The amount of the expandable phenolic resin composition forming the granular layer also varies depending on conditions such as the porosity of the aggregate particle layer and the intended foam density. Usually, the amount and thickness of the granular layers constituting the upper and lower layers or the upper and lower layers and the intermediate layer are determined so that the average density of the expandable phenolic resin composition is 5 g/or more relative to the capacity in the mold. Suitable, preferably 5 to 300 g/. Although a mold that can be closed as described above is used as the molding mold, it is appropriate to use a mold that at least discharges air inside the cavity during foaming. According to the manufacturing method of the present invention, a granular layer of a foamable phenolic resin composition is formed at the bottom and top of a mold, and then foam curing is performed to integrate aggregate particles with the phenolic resin foam layer. Therefore, it is possible to obtain a foamed composite with a kind of sandwich structure in which the foam layer on the surface has a high density and the density inside is relatively low. As a result, the flexural modulus is significantly improved and the surface hardness is also increased. (E) Examples Example 1 A mold was used which had internal dimensions of 25 mm in height, 250 mm x 250 mm in width, a flat bottom surface, and a flat lid that could be opened and closed. A release paper was placed on the bottom of the mold, and then 31.3 g of the foamable phenolic resin composition was spread to a uniform thickness to form a powder layer of the composition.
The composition used in this case was a powder obtained according to the following formulation. [Expansible phenolic resin composition] (a) Uncured novolak type phenol-formaldehyde resin (melting point: 81°C, gelation time: 150°C, 76 seconds)
100 mesh pass remaining 0.5%) 100 parts by weight (b) Hexamethylenetetramine (curing agent)
10 parts by weight (c) Dinitropentamethylenetetramine (foaming agent) 10 parts by weight (*100 mesh powder obtained by mixing the above (a), (b), and (c) in a roll mixer at 80°C for 5 minutes and pulverizing the mixture) Next, 140 g of pearlite particles (trade name: Fuyolite: Fuyolite Kogyo Co., Ltd.) with an average particle size of 5 mm are placed in the mold as aggregate particles on the above composition layer without being substantially mixed with the composition. The mold was filled almost uniformly (filling degree 100%).
Furthermore, 31.3 g of the same foamable phenolic resin composition as above was spread to a uniform thickness to form a powder layer of the composition, and after spreading release paper, the lid was covered and pressed at 150°C. At a pressure of 2Kg/ ^cm3
Press heating was performed for 20 minutes. In the obtained phenol foam composite, pearlite grains are uniformly dispersed throughout the phenol foam, and when cut, there are voids between the grains (porosity: 40%).
was completely filled with phenol foam, but the density of the phenol foam on the surface was 115 kg/
m ³ and the surface density at the center was 87 Kg/m ³ . The physical properties of this composite are shown in the table. Example 2 A composite was produced in the same manner as in Example 1 except that the amount of the foamable phenolic resin composition uniformly spread on the bottom and top surfaces was changed to 23.4 g. The obtained phenol foam complex was prepared in Example 1.
Similarly, pearlite grains were uniformly dispersed throughout the phenol foam, and when it was cut, the voids between the grains (porosity 40%) were all filled with phenol foam, but the density of the phenol foam on the surface was 98Kg/m ³ and the surface density in the center is 60Kg/
It was ^m3 . The physical properties of this composite are shown in the table. Example 3 A composite was produced in the same manner as in Example 1, except that 15.6 g of each expandable phenol foam resin was uniformly spread on the bottom, middle, and top surfaces.The obtained phenol foam composite was produced as in Example 1.
Similarly, pearlite grains were uniformly dispersed throughout the phenol foam, and when cut, the voids between the grains (40% porosity) were completely filled with phenol foam, but the density of the phenol foam on the surface was 58 kg/ The density at a distance of 7 mm from the surface of m ³ is 42
It was Kg/ ^m3 . The physical properties of this composite are shown in Table 1. Comparative Example 1 Phenol resin composition powder produced under the same conditions as in Example 1 using pearlite grains (trade name: Fuyolite, Fuyolite Industrial Co., Ltd.) with an average particle size of 5.0 mm as aggregate was processed using a pan-type granulator. , and granulated for 3 minutes. In this case, water was used as the binder and was sprayed in a mist form from a nozzle. The ratio of raw materials during granulation is approximately 3 parts binder to 200 c.c. (bulk) of aggregate.
cc, 80 g of powder of foamable phenolic resin composition. Next, the coated particles obtained in this step were air-dried all day and night, and then dried for 6 hours in a hot air circulation constant temperature bath at 70°C. In the obtained coated particles, the foamable resin composition powder was bonded to the surface of the aggregate pearlite particles (trade name: Fuyolite, Fuyolite Industries Co., Ltd.), and did not peel off even when handled roughly. Please note that this coating has not yet completely foamed and has an average of 0.27
It was about mm thick. Next, place this coated particle on talc powder for 160 min.
The foam was cured for 30 minutes in a constant temperature bath with hot air circulation at ℃. The resulting foam has a yellowish tinge and a particle size of 10-14
It was a composite foam sphere with pearlite inside (aggregate) and a foam tank novolak type phenolic resin with a dense cell structure outside. Next, the coated composite foam spheres were filled into the same mold (25 x 250 x 250 mm) as in Example 1 to almost full capacity (100%), the lid was closed, and the mold was kept at a constant temperature of 160°C with hot air circulation. It was kept in the tank for 1 hour. Thereafter, the mold was taken out of the thermostatic oven, and the foamed molded article was taken out from the mold. In the obtained phenol foam composite, pearlite grains are uniformly dispersed throughout the phenol foam, and when cut, the voids between the grains (porosity 40
%) was uniformly filled with all the phenolic forms. The physical properties of this composite are shown in the table. Comparative Examples 2 and 3 Composites were produced in the same manner as in Comparative Example except that the amount of expandable phenol resin coated on Perlite (trade name: Fuyolite, Fuyolite Kogyo Co., Ltd.) was changed to 60 g and 50 g, respectively. In the obtained phenol foam composite, pearlite grains are uniformly dispersed throughout the phenol foam, and when cut, the voids between the grains (porosity 40
%) was uniformly filled with phenol foam. The physical properties of this composite are shown in the table.

[Table] Example 4 170 g of foamed glass particles with an average particle size of 3.7 mm (product name: Cellobeads Toyota Boshoku Co., Ltd.) as aggregate particles
A composite was produced in the same manner as in the example except that (filling degree was 60%). In the obtained phenol foam composite, pearlite grains were almost entirely dispersed, and the spaces between each grain were completely filled with phenol foam. However, compared to Example 1, the gaps between grains were more uniform. The physical properties of this composite were an apparent density of 133 kg/m ³ and a bending strength of 7.7 kgf/cm ² . Example 5 100 parts of uncured novolak type phenol-formaldehyde resin (melting point: 81°C, gelation time: 150°C, 76 seconds, 100 mesh passes, remaining 0.5%), 8 parts of hexamethylenetetramine, 10 parts of dinitrosopentamethylenetetramine, Pronone #208 (Japanese) Manufactured by Yushi Co., Ltd.)
One part was mixed in a mixer. The resulting mixture was passed through a twin-screw extruder [rotating in different directions (parallel shafts), L/D=22]
The cylinder is charged through the hopper, the lower part of the hopper is cooled to 50℃, and the temperature of the cylinder is then controlled at 80℃. The temperature of the mold was controlled at 90°C, and the mixture was poured out of a φ2 mm cylinder and cut into pellets. The pellets were non-foamed. A composite was produced from the pellets in the same manner as in Example 1. The obtained phenol foam complex was prepared in Example 1.
Similarly, pearlite grains were uniformly dispersed throughout the phenol foam, and when cut, the voids between the grains (40% porosity) were completely filled with phenol foam, but the density of the phenol foam on the surface was 110 kg/m ³ and the center was 90Kg/ ^m3 . The physical properties of this composite were an apparent density of 150 Kg/m ³ and a flexural modulus of 1480 Kgf/cm ² . Example 6 A primary foamed cylindrical phenol foam was produced in the same manner as in Example 5, except that the twin-screw extruder was used, the cylinder temperature was changed to 95°C, and the mold temperature was changed to 110°C. The primary foamed cylindrical phenol foam had an average size of 5 mmφ x 6 mm and an apparent density of 400 Kg/m ³ . A composite was produced from this primary foamed cylindrical phenol foam in the same manner as in Example 1. As in Example 1, the obtained phenol foam composite had pearlite grains uniformly dispersed throughout the phenol foam, and when cut, it was found that the voids between the grains (porosity 40%) were completely filled with phenol foam. However, the density of phenol foam on the surface was 113Kg/m ³ and in the center was 88Kg/m ³ . The physical properties of this composite were an apparent density of 150 Kg/m ³ and a flexural modulus of 1450 Kgf/cm ² . Example 7 10 parts by weight of a blowing agent dinitrosopentimethylenetetramine was added to 100 parts by weight of a resol-type phenolic resin initial condensation powder, and the mixture was kneaded using heated rolls. Thereafter, it was pulverized to obtain a powdered resin composition. This foamable resin composition had a melting point of 75°C after 100 mesh passes. A composite was produced in the same manner as in Example 1, except that 31.3 g of the above-mentioned resol type phenolic resin initial condensation powder was uniformly spread on the bottom and top surfaces. The obtained phenol foam complex was prepared in Example 1.
Similarly, pearlite grains were uniformly dispersed throughout the phenol foam, and when it was cut, all the phenol foam was filled in the voids between the grains (porosity 60%), but the density of the phenol foam on the surface was 113 kg/ m ³ and the surface density at the center is 82Kg/
It was ^m3 . The properties in this complex have an apparent density of 150
Kg/m ³ and flexural modulus of 1470 Kgf/cm ² . Comparative Example 4 A composite was produced in the same manner as in Example 1, except that pearlite particles and a foamable phenolic resin composition were mixed and filled. When the pearlite grains and the expandable phenolic resin composition were mixed, some of the pearlite grains were lost and pearlite powder was generated. Then, I intentionally filled the mixture to make it as uniform as possible to avoid uneven mixing.
The obtained phenol foam composite was non-uniform, with some parts having only a phenol foam layer, and air pockets partly occurring inside the composite. This air pocket is thought to occur because the foamable phenolic resin composition is heated and foamed from the upper and lower surfaces, so there is no space for air to escape. (F) Effects of the Invention According to the method of the present invention, a foamed phenolic resin composite having a high flexural modulus and high surface hardness can be obtained very easily. Since the phenol foam composite of the present invention thus obtained is composed of phenol foam containing aggregate particles, it is useful for applications requiring fire resistance, such as heat-resistant materials, panel core materials, and ceiling materials. can be,
In particular, a phenol foam composite board molded using a plate-shaped mold can be suitably used as an exterior board (sizing board) for construction by laminating it with a metal plate.

[Brief explanation of drawings]

1 to 5 are configuration explanatory views showing each step of the manufacturing method of the present invention, respectively. 1, 1', 8...Grain layer, 2...Mold, 5...
Aggregate particles, 6... Upper mold, 7... Foamed phenolic resin composite.

Claims (1)

[Scope of Claims] 1. A granular foamable phenolic resin composition consisting of a phenolic resin initial condensate, a decomposable foaming agent, and a curing agent added as necessary is introduced into a mold, and the composition is placed in the bottom of the mold. forming a granular layer of material, then (a) depositing aggregate particles on the granular layer without substantially intermixing with the granular layer to form an aggregate particle layer; and (b) forming an aggregate particle layer. The step of spraying the foamable phenolic resin composition again on the aggregate particle layer to form a granular layer of the composition is repeated once to multiple times to form a granular layer of the foamable phenolic resin composition on the bottom and top. A composite layer is formed in which a layer of aggregate granules having an expandable phenolic resin composition layer is optionally interposed between the layers, and then the mold is heated in a closed state to form an expandable phenolic resin composition. A method for producing a foamed phenolic resin composite, characterized in that a foamed composite having a high density surface foam layer and a low density internal foam layer is obtained by foaming and curing.