JPS61103942A - Expandable resin-coated particles - Google Patents

Abstract

PURPOSE:To obtain the titled particle having excellent storage stability, workability, etc., and giving a uniform foamed article having arbitrary shape, by coating an aggregate particle with a foamable solid resin composition containing a resol-type phenolic resin condensate and a decomposition-type foaming agent as essential components. CONSTITUTION:A foamable solid resin composition containing 100pts.wt. of a solid resol-type phenolic resin precondensate and 1-50pts. of a decomposition- type foaming agent (e.g. N,N'-dinitrosopentamethylenetetramine) is attached in molten state to aggregate particles consisting of organic particles (e.g. foamed particles of resol-type phenolic resin) and/or inorganic particles (e.g. perlite). The amount of the foamable resin composition is >=5g, preferably 15-500g per 1 liter of the particle.

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 is 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 phenolic resin molded product by mixing this composition with other particles, it is necessary to make the particles have a size of 1 cod or less and a bulk specific gravity of the above composition. If the mixture is not the same as that of the phenolic resin, it is difficult to obtain a uniform mixture, and even if the mixture is heated and foamed, it is extremely difficult to obtain a uniformly foamed phenol resin molded product.

In view of the above circumstances, the inventors of the present invention have determined that when obtaining a phenolic resin molded article, 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 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 the molded product. 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 resol-type phenolic resin foam 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-warm 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 base 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% of reaction water, but it is further dehydrated (evaporating water) to form a solid product (containing about 1% of water).
Then, this solid material is pulverized to obtain a powdered resol type phenolic resin used in the present invention.
,.

In addition to phenol, the above-mentioned phenols include 8.5-xylenol, m-cresol, 2.5-xylenol,
Included are 3,4-xylenol, 2,4-xylenol, 0-cresol, p-cresol, and the like. Also, aldehydes include formaldehyde, paraformaldehyde,
Includes hexamethylenetetramine, furfural, acetaldehyde, acetals, etc. A preferred precondensate for use in this invention is a condensate of phenol and formaldehyde.

In this invention, the decomposable foaming agent means that when the composition is mixed with the resol type phenolic resin initial condensate and cured by heating!
Refers to inorganic and organic blowing agents that can be zeta-decomposed to generate gas. 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, Examples include inorganic decomposition blowing agents such as ammonium carbonate, ammonium bicarbonate, ammonium nitrite, and azide compounds (eg, CaN6).

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 the appropriate amount is 1 to 50 parts by weight per 100 parts by weight of the resol type phenolic resin.
4 to 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 is usually produced by kneading its components, such as a resol-type phenolic resin initial condensate and a decomposition-type blowing agent (and other additives), using heated rolls, etc., to uniformly mix them, and then pulverizing them. It is used in powder form with an outer diameter of less than 1++wJl.

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 substances include perlite, shirasu balloon,
Examples include glass balloons, glass foam granules, crow cotton granules, rock wool granules, slap, clay foam granules, sand, plaster granules, and metallic granules.

Examples of the organic material include synthetic resin particles and foamed particles thereof, wood powder particles, abrasive grains, etc., but resins having heat resistance of 100°C or higher are generally preferred, such as resol type phenolic resin foamed particles, styrene-maleic anhydride, etc. Examples include acid 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, pulverized fragments, or irregularly shaped. The size of the particles may be any size from microscopic particles with a particle diameter of 1 mil to large particles with a particle diameter of 40 to 50 mil. Furthermore, the density of aggregate particles is not particularly limited;
When considering the use of lightweight foam molded products, the density if/
It is sufficient to select aggregates having a density of i or less, and high-density aggregates may also be used.

The method of coating the aggregate particles with the foamable resin composition includes a temperature range of 1 degree in which the powdery foamable resin composition melts and adheres;
In other words, aggregate particles are heated to a temperature ranging from the softening point of about 70°C to about 110 to 120°C, which is the point of foaming and hardening, and in this state, a foamable resin composition (in powder form) is sprayed.
There is a method in which coated particles are obtained by contacting the foamed composition by sprinkling or the like, or conversely, a method in which the foamable composition is heated and softened to coat the 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 binder may be sprayed and then rolled together with the aggregate particles and the powdered foamable resin composition in a pan-type granulator. 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 foaming ratio and bubbles7. 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 an 8-5% 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 cover 51 weight or more per liter of aggregate particle volume. Good coverage is 15 to 600 f.

The coating state at this time is good, in which the composition is uniformly coated on the aggregate particles, but if a molded article is obtained, a patchy coating state is also acceptable.

In addition, 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, a foamable resin composition is usually placed in a mold having a desired shape with a bulk volume of 20
~100% filling and a predetermined temperature (e.g. 150~180
When heated to a temperature of about 'C), each particle easily expands and a foamed molded product can be obtained in which the particles are fused and integrated. 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 aggregate particles are not present 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 composed of aggregate particles coated with a foamable resin composition containing a resol type phenolic resin initial condensate and a decomposable foaming agent as essential components, A resol type phenolic resin foam molded article containing aggregate particles is provided, which is characterized in that aggregate particles are substantially uniformly dispersed.

The shape of the molded product of this invention is not particularly limited, but may be plate-shaped,
It may be cylindrical or the like.

For example, if it is plate-shaped, it can be used as a heat insulating board for construction.
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.

(Examples) Next, the present invention will be explained by examples, but the present invention is not limited by these examples.

Example 1 10 parts by weight of a blowing agent dinitrosopenta was added to 100 parts by weight of a powdered resol type phenolic resin having a flow rate of 70 to 100 cm at 125'O, a gel time of 85 to 1051 m at 150°C, and a softening point of 78°C. Mix methylenetetramine,
A powdered foamable resol type phenolic resin composition was obtained.

Next, the above resin composition powder was granulated for 8 minutes using a pan-type granulator using resol deaf phenolic resin spherical foam having an average particle size of 6.0 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.

In addition, the raw material ratio during granulation is aggregate 1000.
tcc@), 8 cc of the binder and 80 cc (volume) of the powdered resol type phenolic resin composition.

Next, the coated particles obtained in the grain process were air-dried for a day and night, and then dried for 8 hours in a hot air circulation thermostat 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 phenol resin foamed particles) to form a thin film, and the powder is disordered. It did not peel off even when handled. In addition,
The coating was not yet fully foamed and had an average thickness of 66 microns.

Next, the coated particles were placed on talc powder and foamed and hardened in a hot air circulation constant temperature bath at 160° C. for 10 minutes.

The obtained foam is yellowish brown, has a particle size of 6 to 9 fl, and is spherical with a skin on the surface, with resol type phenolic resin foam particles present inside (aggregate) and a dense cell structure outside. It was a composite foaming method in which the foam layer included a resol type phenolic resin.

This coated composite foaming process was then applied to a metal mold (220X
220 x 25 m) with a bulk volume almost full (100
%), 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 foam.

In this foamed molded product, the powder resol type phenolic resin foam layer on the surface further expands, and the powder resol type phenol 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 product in which the aggregate (resol type phenol resin foam particles) was uniformly dispersed. Incidentally, the density of this molded body is 200 kl/w! Met.

In addition, when a metal mold is filled with 50% cavity volume using the above composite foaming method and heated, the aggregate is uniformly dispersed in the molded product, and the particles are filled with yellow foam foamed in a high-magnification wheel. It is a molded product completely filled with a powder resol type phenolic resin foam layer with a colored and dense cell structure, and the density is 100 d.
/d.

Example 26.8. Other examples of granulation using methyl alcohol and trichlorotrifluoroethane (F 11g ) as 4° 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.

G? ! Example 5゜The powder of the foamable resin composition is 5j! The resin composition powder was prepared in the same manner as in Example 1, and then the above resin composition powder was mixed with a pan-shaped granulator using foamed glass (trade name: Cellobeads, Toyoda Boshoku Co., Ltd.) with an average particle size of 8.7 as an aggregate. In this case, water was used as the binder and was sprayed in a mist form from a nozzle.

In addition, the raw material ratio at the time of coating is 1000cc of aggregate (
The binder has a volume of 10 cc, and the resol type phenolic resin composition powder has a volume of 80 cc.

Next, the coated particles obtained in this step were air-dried for a day and night, and
It was dried for 4 hours in a hot air circulation constant temperature bath at ℃.

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, the coated particles were placed on talc powder and foamed and hardened for 80 minutes in a hot air circulation constant temperature bath at 160°C.

The resulting foam is yellowish brown, has a particle size of 5 to 8, has a skin on the surface, and is a spherical resol type phenol covered with a foam layer with a dense cell structure containing foamed glass particles inside. It was a resin composite foam ball.

Examples 6, 7 and 8 Other examples coated using water as the binder are shown in Table 2, including Example 5. Note that the ratio of raw materials during coating is the same in all cases.

(Margin below, continued on next page.) Example 9゜ The powder of the 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 8.7 square meters as an aggregate.

In addition, the binder at that time has a molecular weight of 190 to 210.
Polyethylene glycol was used and sprayed from a nozzle. In addition, the raw material ratio at the time of coating is aggregate 1000
cc (volume), the binder was 10 cc, and the resol type phenolic resin composition powder was 80 cc (volume).

The coated particles obtained by this process 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 65 μm.

Next, this coated particle is placed on talc powder and 160'
It was foamed and cured for 80 minutes in a hot air circulation constant temperature bath.

The obtained foam is a spherical resol-type phenolic resin composite foam sphere that has a brownish color and a particle size of 6 to 9 mm, has a skin, has foam glass particles inside, and is covered with a surface layer of a foam layer. there were.

Example 10 A powder of a 0° foamable resin composition was prepared in the same manner as in Example 1.

Next, foamed glass with an average particle size of 8.7 was heated for 2 hours in a hot air circulation constant temperature bath at 180'C, quickly taken out from the chamber, and placed in a pan-shaped granulator pre-adjusted to an atmosphere of 60C. The resin composition was poured into the heated powder and coated.

The raw material ratio during coating is 80 cc (volume) of resol resin composition powder to 1000 cc (volume) of foamed glass particles as aggregate.

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The foamable resin composition powder was softened and melted and adhered to the surface of the '□, forming a uniform thin film. Note that this coating did not peel off even when handled roughly. Moreover, this coating had an average thickness of 45 microns.

Next, the expandable coated particles are placed on talc powder and 16
It was foamed and cured for 80 minutes in a hot air circulation constant temperature bath at 0°C.

The resulting foam is a resol-type phenolic resin composite foam sphere that is yellowish brown in color, has a particle size of 6 to 9, has a skin, and is covered with a foam layer with a dense cell structure in which foamed glass particles exist inside. Met.

Ff:27. -1;-! Tsuyu Agent Patent Attorney Shinta Nogawa 1 Shidate-2b

Claims (1)

[Claims] 1. Foaming 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 1 liter volume of aggregate particles is at least 5 g.