JPH0464333B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to particles having foamability, in which the surface of granular aggregate is coated with a resin composition having foamability. Conventionally, a foamable resin composition prepared by mixing a novolak-type phenolic resin initial condensate with a required amount of a decomposable blowing agent and a curing agent is usually used in the form of powder, and the size of the powder is 100 mesh or more. The bulk specific gravity is also usually 1 or less. In order to obtain a phenolic resin molded body by mixing this composition and other particles, it is difficult to obtain a uniform mixture unless the particle size is 1 mm or less and the bulk specific gravity is about the same as that of the above composition. Even when heated and foamed, it was extremely difficult to obtain a uniformly foamed phenolic resin molded product. In view of the above circumstances, the inventors of the present invention have determined that when obtaining a molded body of phenolic resin, aggregate particles that are not reactive with the foamable resin composition to be coated, regardless of the shape, size, bulk specific gravity, etc. The inventors discovered the fact that a uniform foamed phenolic resin body can be easily obtained by coating the composition in advance, filling a mold with the foamable resin-coated particles, and heating the mold. Reached. Thus, the gist of the present invention is to provide a foamable resin composition in which aggregate particles are coated with a foamable resin composition containing as essential components a novolac-type phenolic resin initial condensate, a decomposable foaming agent, and a curing agent. Present in resin-coated particles. When heated, the expandable resin-coated particles become a heat-insulating granular material containing aggregate on the inside and covered with a novolak-type phenolic resin foam layer on the outside. For example, if the particles of the present invention are filled into a mold or the like and heated, a phenol molded body in which aggregate particles are uniformly dispersed in the phenol foam can be obtained. The novolak type phenolic resin initial condensate, which is the main raw material of this invention, is a so-called novolak type phenolic resin known in the art, which is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst, and is cured. It means that polymerization can proceed further in the presence of the agent. What are phenols?
In addition to phenol, 3,5-xylenol, m-
Cresol, 2,5-xylenol, 3,4-xylenol, 2,4-xylenol, O-cresol, p-cresol and the like are included. The aldehydes include formaldehyde, paraformaldehyde, hexamethylenetetramine, furfural, acetaldehyde, acetals, and the like. These resins are generally in powder form at room temperature.
Preferred initial condensates for use in this invention are:
It is a condensate of phenol and formaldehyde. In the present invention, the decomposable blowing agent refers to inorganic and organic blowing agents that can decompose and generate gas during heat curing in a composition prepared by mixing a novolak type phenolic resin initial condensate and a curing agent. Typical examples of these include organic decomposable blowing agents such as N,N'-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, azobisisobutyronitrile, azodicarbonamide, and paratoluenesulfonyl hydrazide, as well as sodium bicarbonate, Ammonium carbonate, ammonium bicarbonate, ammonium nitrite, azide compounds (e.g. CaN ₆ )
Inorganic decomposition type foaming agents such as All of these are in powder form. The curing agent used in this invention means a compound that can be decomposed by heating and can undergo a crosslinking reaction with the novolak type phenolic resin initial condensate. Such compounds include, like formaldehyde, compounds that are used to form phenolic resins by reaction with phenols, and are usually in powder form. Specific examples include hexamethylenetetramine, paraformaldehyde, methylal, dioxolane, trioxane, tetraoxane, trimethylolphosphine, S-triazine, and the like. The amount of the blowing agent to be added is determined mainly by considering the desired density of the final foam, but 1 to 50 parts by weight is appropriate for 100 parts by weight of novolak type phenolic resin, and 4 to 50 parts by weight are suitable. 8 parts by weight is preferred. 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. The foamable resin composition of the present invention may contain small amounts of various other 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 novolak type phenolic resin. The foamable resin composition in this invention usually includes:
Its components, such as a novolac-type phenolic resin initial condensate, a decomposable blowing agent, and a curing agent (and other additives), are kneaded and mixed uniformly using heated rolls, etc., and then pulverized to form a powder with an outer diameter of 1 mm or less. used in Of course, granules may also be used. The aggregate may include organic or inorganic particles or mixtures thereof, but preferably aggregates that do not react with the foamable resin composition. Examples of inorganic materials include perlite, shirasu balloons, glass balloons, glass foam particles, glass cotton particles, rock wool particles, slag, clay foam particles, sand, plaster 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 method for coating the aggregate particles with the foamable resin composition is as follows: from the temperature range at which the powdered foamable resin composition melts and adheres, that is, the softening point of about 80°C;
A method of obtaining coated particles by heating aggregate particles to a temperature in the range of about 110 to 120°C at which they foam and harden, and in this state, spraying a foamable resin composition (powder form) and bringing them into contact with each other by sprinkling, etc. Conversely, there is a method in which the foamable composition is softened by heating and coated on aggregate particles. Another method is to use a binder. Typical binders include water, methyl alcohol, toluene, and the like. Among these, water is most preferred. When such a binder is used, for example, the aggregate particles and the powdered foamable resin composition may be rolled together in a pan-type granulator while spraying the binder. When these binders are used, it is preferable to remove the binders through a drying process after coating and granulation. This is because, for example, if water remains, it may have an adverse effect on the expansion ratio and bubbles. Further, any binder may be used as long as it does not adversely affect the foaming process. For example, other binders that may be used include a 3-5% aqueous solution of sticky polyvinyl alcohol, silicone oil, animal and vegetable oils, and the like. When these binders are used, they remain in the coated particles of the present invention, and such coated particles are also included in the present invention. The amount of coating of the foamable resin composition on the aggregate particles varies depending on the foamability of the composition, the type and shape of the aggregate, etc., but it is usually necessary to coat the aggregate particles with a weight of 5 g or more per 1 liter volume of the aggregate particles. Good coverage is 15-500g. The coating condition at this time is good enough that the composition is evenly coated on the aggregate particles, but
When obtaining a molded product, even if it is covered with a patchy coating,
I don't care. Note that the coating resin composition of the obtained expandable resin-coated particles of the present invention may be a composition having secondary foamability, which is partially foamed and cured. Such expandable resin-coated particles can be formed into a foam molded article of any shape. For example, a mold having a desired shape is filled with a foamable resin composition, usually 20 to 100% of its bulk volume, and then heated to a predetermined temperature (for example, 150 to 100%).
When heated to a temperature of about 180°C, each particle easily expands and is fused together to form a foamed molded product. The foamed molded product obtained here differs from one in which the foamable resin composition and aggregate particles are simply mixed and foamed, and the aggregate is substantially uniformly dispersed in the foamed product. Here, a molded product in which aggregate particles are substantially uniformly dispersed means that the aggregate particles are not concentrated only in the surface layer or center of the molded product. Therefore, a molded body in which the aggregate particles are substantially uniformly dispersed is obtained, so that such a molded body has various quality characteristics such as high dimensional stability and uniform heat insulation effect. In addition, during foam molding, it has been recognized that aggregate is substantially uniformly dispersed in the foam molded product even at a filling rate as low as 20% of the bulk volume, and this fact was confirmed by the inventors of the present invention. This is one of the new and surprising findings discovered by researchers. Thus, according to one aspect of the present invention, a foamed material is prepared in which aggregate particles are coated with a foamable resin composition containing as essential components a novolak-type phenolic resin precondensate, a decomposable blowing agent, and a curing agent. Thus, there is provided a novolak type phenolic resin foam molded article containing aggregate particles, characterized in that the aggregate particles are substantially uniformly dispersed. The shape of the molded article of the present invention is not particularly limited, but may be plate-shaped, cylindrical, or the like. For example, if it is plate-shaped, it can be used as a heat insulating board for buildings, and if it is cylindrical, it can be used as a heat-insulating material to cover pipes. Furthermore, this molded product is very lightweight and has excellent adhesiveness to other objects (for example, iron plates, etc.), so it is suitable as a composite molded product such as a sizing board. Next, the present invention will be described with reference to Examples, but the present invention is not limited thereby. Example 1 5 parts by weight of a blowing agent dinitrosopentamethylenetetramine and 10 parts by weight of a hardening agent hexamethylenetetramine were added to 100 parts by weight of a novolac type phenol-formaldehyde resin powder, and the mixture was kneaded with a heated roll. Thereafter, it was pulverized to obtain a powdered resin composition. This foamable resin composition is a powder with a 100 mesh residue of 0.5%, and has a melting point of 81℃ and 150℃.
The gelation time was 76 seconds. Next, the resin composition powder was granulated for 3 minutes using a pan-type granulator using a resol-type phenol-formaldehyde resin spherical foam having an average particle size of 5.0 mm as an aggregate. Note that water was used as the binder at that time, and was sprayed in a mist form from a nozzle. The ratio of raw materials during granulation is approximately 3 c.c. of binder and 75 c.c. (bulk) of novolac type phenolic resin composition powder to 200 c.c. (bulk) of aggregate. 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 (resol type phenolic resin foamed particles), and did not peel off even when handled roughly. Note that this coating was not yet completely foamed and had an average thickness of 0.27 mm. 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 is a composite foam sphere that is spherical with a skin on the surface and has resol type phenolic resin foam particles inside (aggregate) and a novolac type phenolic resin foam layer with a dense cell structure outside. Ta. Then, this coated composite foam sphere is placed into a metal mold (220×220×25mm) almost full (100%) with bulk volume.
The container was filled with water, the lid was closed, and the container was kept in a hot air circulation constant temperature bath at 160°C 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 foam molded product, the novolak type phenolic resin foam layer on the surface further foams, and all the voids between the filled particles are filled with the novolak type phenolic resin foam layer with a yellowish and dense cell structure. It was a novolak-type phenolic resin composite foam molded product in which the particles were completely bonded and the aggregate (resol-type phenolic resin foamed particles) was uniformly dispersed. Incidentally, the density of this molded body was 350Kg/m ³ . In addition, the bulk volume of the above composite foam ball is 30% in a metal mold.
When filled and heated, the aggregate is uniformly dispersed in the molded product, and the space between the particles is a novolac-type phenolic resin foam layer with a dense, yellowish cell structure that has been expanded to a high magnification. It was a fully filled composite foam molded product with a density of 100 Kg/m ³ . Examples 2, 3 and 4 Other examples of coatings using water as a binder are shown in Table 1, including Example 1. Note that the ratio of raw materials during coating is the same as in Example 1.

[Table] Example 5 A powder of a foamable resin composition was prepared in the same manner as in Example 1. Next, foamed glass (trade name: Cellobeads, manufactured by Toyota Boshoku Co., Ltd.) with an average particle size of 3.7 mm was used as an aggregate, and the above resin composition powder was coated in a pan-shaped granulator. A mixture of methyl alcohol (special grade reagent) and trichlorotrifluoroethane in a volume ratio of 1:5 was used as a mist, which was sprayed from a nozzle.The raw material ratio during coating was 200 c.c. of aggregate. (bulk), the binder is approximately 3 c.c., and the novolak-type phenolic resin composition powder is 75 c.c. (bulk). Next, the coated particles obtained in this step are air-dried overnight, and It was dried for 72 hours in a hot air circulating constant temperature oven.The obtained coated particles were obtained by melting the foamable resin mixture powder onto the surface of the aggregate (foamed glass particles) and fused to form a thin film. , the powder was completely dissolved and solidified.Also, this coating was
Even when handled roughly, it did not peel off. Note that this coating had an average thickness of 0.15 mm. 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 is yellowish and has a particle size of 8-10
It was a spherical novolac-type phenolic resin composite foam sphere with a skin on the surface and covered with a foam layer with a dense cell structure containing foamed glass particles inside. Examples 6, 7 and 8 Other examples of granulation using methyl alcohol and trichlorotrifluoroethane (F113) as binders are shown in Table 2, including Example 5. Note that the ratio of raw materials during coating is the same in all cases.

[Table] Example 9 A powder of a foamable resin composition was prepared in the same manner as in Example 1. Next, the resin composition powder was coated using a pan-shaped granulator using foamed glass having an average particle size of 3.7 mm as an aggregate. In addition, the binder at that time should have a molecular weight of 190~
210 polyethylene glycol was used and sprayed from a nozzle. The raw material ratio during coating is 200 c.c. (bulk) of aggregate, 5 c.c. of binder, and 80 c.c. (bulk) of novolak type phenolic resin composition powder.
It is. Next, the coated particles obtained in this step were allowed to stand overnight. The obtained coated particles had the foamable resin mixture powder attached to the surface of the aggregate (foamed glass particles) due to the presence of a binder, and did not peel off even when handled roughly. . Note that this coating had an average thickness of 0.22 mm. This coated particle is then placed on talc powder,
The foam was cured for 30 minutes in a hot air circulation constant temperature bath at 160°C. The obtained foam has a brownish color and a particle size of 6 to 9 mm.
It was a spherical novolak-type phenolic resin composite foam sphere with a skin, foam glass particles inside, and a surface layer of a foam layer. Example 10 A powder of a foamable resin composition was prepared in the same manner as in Example 1. Next, foamed glass with an average particle size of 3.7 mm was heated for 2 hours in a hot air circulation constant temperature bath at 180°C, quickly taken out from the tank, and heated in a pan-shaped granulator pre-adjusted to an atmosphere of 60°C. It was poured into a resin composition powder and coated. The raw material ratio during coating was 75 c.c. (bulk) of the novolak resin composition powder to 200 c.c. (bulk) of foamed glass particles as aggregate. This obtained coated particle is aggregate (foamed glass)
The foamable resin composition powder was softened and melted and adhered to the surface of the sample, forming a uniform thin film. Note that this coating did not peel off even when handled roughly. Also, this coating has an average
It was 0.15mm thick. Next, the expandable coated particles were placed on talc powder and foamed and hardened for 30 minutes in a hot air circulation constant temperature bath at 160°C. The resulting foam is yellowish and has a particle size of 8-10
It was a novolak-type phenolic resin composite foam sphere, which had a skin of 2 mm in diameter and was covered with a foam layer with a dense cell structure containing foamed glass particles inside.

Claims (1)

[Scope of Claims] 1. A foaming property characterized in that aggregate particles are coated with a foamable resin composition containing a novolak type phenolic resin initial condensate, a decomposition type foaming agent, and a curing agent as essential components. Resin coated particles. 2. The particles according to claim 1, wherein the aggregate particles are organic or inorganic particles or a mixture thereof. 3. The particles according to claim 2, wherein the organic particles are foamed resol type phenolic resin particles or foamed styrene-maleic anhydride copolymer resin particles. 4. The particles according to claim 2, wherein the inorganic particles are perlite, shirasu balloons, glass balloons, glass foam particles, glass cotton particles, rock wool particles, or crushed products thereof. 5. The particles according to claim 1, wherein the foamable resin composition is in powder form, and the size thereof is smaller than the size of the aggregate particles. 6. The particles according to claim 1, wherein the amount of foamable resin composition used per liter of aggregate particles is at least 5 g.