JPH0464539B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Object of the invention (industrial field of application) The present invention relates to foamable particles in which the surface of granular aggregate is coated with a solid foamable resin composition. (Prior Art) Conventionally, a foamable resin composition prepared by mixing a resol-type phenolic resin initial condensate and a required amount of a decomposition-type foaming agent has been used even if it is powdered, and the size of the powder is 100 mesh or more. The bulk specific gravity is also usually 1 or less. (Problems to be Solved by the Invention) However, in order to obtain a molded body of phenolic resin by mixing this composition with other particles, the size of the particles must be 1 mm or less, and the bulk specific gravity must be equal to or less than the composition described above. If the level is not the same, it will be difficult to form a homogeneous mixture.
Even when heated and foamed, it is 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 homogeneous phenolic resin foam molded product can be easily obtained by coating the composition in advance, filling a mold with the foamable resin-coated particles, and heating, etc., which led to the present invention. Reached. (B) Structure of the Invention According to the present invention, aggregate particles are coated with a solid foamable resin composition containing a solid resol type phenolic resin initial condensate and a decomposable foaming agent as essential components. Provided are expandable resin-coated particles characterized by: When heated, the expandable resin-coated particles become heat-insulating granular materials containing aggregate on the inside and covered with a resol-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 resol-type phenolic resin initial condensate, which is the main raw material of this invention, 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. It means an acidic curing accelerator or a substance that can further progress polymerization by heating.
Such resol type phenolic resin is a liquid containing about 20% reaction water, which is further dehydrated (evaporates water) to form a solid (containing about 1% water), and then this solid The shaped product is pulverized to obtain a powdered resol type phenolic resin used in the present invention. 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 precondensate for use in this invention is a condensate of phenol and formaldehyde. The decomposable blowing agent in the present invention refers to inorganic and organic blowing agents that can decompose and generate gas during heat curing in the composition mixed with the resol type phenolic resin initial condensate. Representative examples of these include 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. ,
Inorganic decomposition blowing agents such as azide compounds (eg CaN ₆ ) may be mentioned. 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, and 4 to 50 parts by weight, based on 100 parts by weight of the resol type phenolic resin. 8 parts by weight is preferred. 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 resol type phenolic resin. The foamable resin composition in this invention usually includes:
Its components, such as a resol-type phenolic resin initial condensate and a decomposable blowing agent (and other additives), are kneaded and mixed uniformly using heated rolls, etc., and then pulverized and used in the form of a powder with an outer diameter of 1 mm or less. Ru. 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 molding strips, 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, from about 70°C, which is the softening point.
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. (c) Effects of the Invention The expandable resin-coated particles according to the present invention can be formed into a foam molded article of any shape. For example, if a mold having a desired shape is filled with a foamable resin composition, usually 20 to 100% of its bulk volume, and heated to a predetermined temperature (for example, about 150 to 180°C), each particle will easily expand. It can be made into a fused and integrated foamed molded product. Further, since the expandable resin-coated particles of the present invention have a solidified coating layer, they are excellent in storage stability, air structure, and filling into molds, and have good workability. 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, the foamed material is made of aggregate particles coated with a foamable resin composition containing a resol type phenolic resin initial condensate and a decomposed foaming agent as essential components. A resol type phenolic resin foam molded article containing aggregate particles is provided, which is characterized in that the agent 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 construction, and if it is cylindrical, it can be used as a heat insulating material for covering 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. (Example) The present invention will be described below with reference to Examples, but the invention is not limited thereto. Example 1 10 parts by weight of the blowing agent dinitrosopentethylenetetramine was added to 100 parts by weight of a powdered resol type phenolic resin with a flow of 70 to 100 mm at 125°C, a gel time of 85 to 105 seconds at 150°C, and a softening point of 73°C. mix,
A granular foamable resol type phenolic resin composition was obtained. Next, the resin composition powder was granulated for 3 minutes using a pan-type granulator using resol-type phenolic resin spherical foam particles having an average particle diameter of 5.0 mm as aggregate particles. In this case, methyl alcohol (special grade reagent) was used as the binder and was sprayed in a mist form from a nozzle. The raw material ratio during granulation is 1000 c.c. of aggregate.
(bulk), the binder was 8 c.c., and the powder resol type phenolic resin composition was 80 c.c. (bulk). Next, the coated particles obtained in this step were air-dried all day and night, and then dried for 3 hours in a hot air circulation constant temperature bath at 50°C. The obtained coated particles are in a state in which dark brown foamable resin composition powder is dissolved and fused to the surface of the aggregate (resol type phenolic resin foamed particles) to form a thin film, and the powder is disordered. It did not peel off even when handled. Note that this coating was not yet completely foamed and had an average thickness of 56 μm. Next, place the coated particles on talc powder at 160°C.
The foam was cured for 30 minutes in a constant temperature bath with hot air circulation. The obtained foam is yellowish brown, has a particle size of 6 to 9 mm, and is spherical with a skin on the surface, and the inside (aggregate)
It was a composite foam sphere in which resol type phenolic resin foam particles were present on the outside, and a resol type phenolic resin foam layer with a dense cell structure was present on the outside. Next, this coated composite foam sphere is placed in a metal mold (220 x 220 x 25 mm) almost full (100%) of its 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. After that, the mold was taken out of the thermostatic oven, and the foam molded article was taken out from the mold. In this foamed molded product, the powder resol type phenolic resin foam layer on the surface further foams, and the powder resol type phenolic resin foam layer with a dense cell structure fills all the voids between the filled particles, completely filling the spaces between the particles. It was a resol type phenolic resin foam molded article in which the aggregate (resol type phenolic resin foam particles) was uniformly dispersed. Incidentally, the density of this molded body was 200 Kg/m ³ . In addition, the above composite foam ball is placed in a metal mold by 50% of the bulk volume.
The filled and heat molded product has aggregates uniformly dispersed in the molded product, and the intergranular space is a powdered resol type phenolic resin foam with a dense cell structure that is yellow and colored at a high magnification. It was a molded body filled with layers and had a density of 100 Kg/m ³ . Examples 2, 3 and 4 Other examples of granulation using methyl alcohol and trichlorotrifluoroethane (F113) as binders 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】

[Table] Example 5 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 (trade name: Cellobeads, manufactured by Toyota Boshoku Co., Ltd.) having an average particle size of 3.7 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 raw material ratio for coating is 1000 c.c. of aggregate.
(bulk), the binder is approximately 10 c.c., and the resol type phenolic resin composition powder is 80 c.c. (bulk). Next, the coated particles obtained in this step were air-dried all day and night, and then dried for 4 hours in a hot air circulation constant temperature bath at 65°C. The obtained coated particles had the foamable resin mixture powder bonded to the surface of the aggregate (foamed glass particles), and the coating did not peel off even when handled roughly. Note that this coating was not yet completely foamed and had an average thickness of 80 μm. Next, place this coated particle on top of the talc powder for 160 minutes.
The foam was cured for 30 minutes in a constant temperature bath with hot air circulation at ℃. The obtained foam has a yellowish brown color and a particle size of 5 to 8.
It was a spherical resol 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 coatings using water as a binder are shown in Table 2, including Example 5. Note that the ratio of raw materials during coating is the same in all cases.

【table】

[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 ratio of raw materials during coating is 1000 c.c. (bulk) of aggregate, 10 c.c. of binder, and 80 c.c. (bulk) of resol type phenolic resin composition powder. 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 55 μm. Next, the coated particles were placed on talc powder and heated to 160°C.
The foam was cured for 30 minutes in a constant temperature bath with hot air circulation. The obtained foam has a brownish color and a particle size of 6 to 9 mm.
It was a spherical resol 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 is 1000 c.c. (bulk) of foamed glass particles as aggregate to 80 c.c. (bulk) of resol resin composition powder. 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 45μ 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 obtained foam has a yellowish brown color and a particle size of 6 to 9.
It was a resol-type phenolic resin composite foam sphere that had a skin of 1.0 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 solid foamable resin composition containing a solid resol type phenolic resin initial condensate and a decomposition type foaming 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.