JPH11349720A - Production of inorganic foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To product the subject lightweight foam capable of highly expanding a stabilized uniform cell structure even when a large amount of an inorganic filler is contained as a main component and excellent in heat insulating properties, etc. by adding an additive such as a vinyl chloride resin or a foaming agent to an inorganic filler as a substrate, kneading the resultant mixture and thermally expanding the kneaded mixture. SOLUTION: (C) An additive in an amount of 32-120 pts.wt. is added to (A) 5-50 pts.wt. of a vinyl chloride resin and (B) 50-95 pts.wt. of an inorganic filler and the resultant mixture is then kneaded to provide a compound, which is then thermally expanded in a metal mold. For example, talc having a fineness so as to pass >=90% thereof through a 150-mesh sieve is used as the component B in order to improve the dispersibility thereof, and a foaming agent such as azodicarbonamide, an organic solvent such as toluene and a plasticizer, etc. such as dimethyl phthalate are preferably used as the component C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an inorganic foam. More particularly, the present invention relates to a method for producing an inorganic foam having heat insulation properties, nonflammability, etc., light weight and sufficient mechanical strength.

[0002]

2. Description of the Related Art Foams formed by closed cells are:
It is lightweight and has excellent heat insulation properties, and is widely used as a heat insulating material for various devices and buildings. Among them, vinyl chloride resin foam is particularly excellent in chemical resistance and mechanical strength. , Widely and commonly used. However, this vinyl chloride resin is flame-retardant but not non-flammable. Further, it has a disadvantage that it is relatively weak to heat and that its volume shrinks in a high-temperature atmosphere, and in particular, a toxic hydrogen chloride gas is generated when exposed to a flame. Therefore, taking advantage of the lightweight and heat-insulating properties of the above-mentioned organic foam, the volume shrinkage ratio is kept small even when heated, and the hydrogen chloride gas generated even in contact with the flame is detoxified and becomes more flame-retardant. For the purpose of conversion, a foam obtained by mixing a polyvinyl chloride resin with an inorganic powder and foaming the mixture has been developed.

For example, it is known that an inorganic filler having water of crystallization in a molecule is mixed with a vinyl chloride resin and heated to generate steam to foam. However, such a foam cannot be uniformly dispersed and foamed when a large amount of the inorganic filler is mixed, and a so-called outgassing phenomenon or the like occurs.
It was difficult to mix more than weight%. It is also known that an inorganic filler and a solvent are added to a vinyl chloride resin, the mixture is kneaded with a closed kneader while heating, a solvent in which liquefied butane is dissolved is mixed, and the mixture is heated and foamed in a mold. . This foam can be kneaded and gelled by adding liquefied butane or the like, so that a sufficient foam can be obtained even if 40% by weight or more of the inorganic filler is blended. However, this also requires at least 25% by weight or more of vinyl chloride resin in order to obtain a foam. Therefore, it is difficult to eliminate the generation of toxic gas or to make it nonflammable when the organic foam comes in contact with a flame, and it is also difficult to sufficiently maintain the workability, shape stability, and the like. there were.

[0004]

SUMMARY OF THE INVENTION In view of the above problems and disadvantages, the present inventors have found that a foam made of an inorganic foam has heat insulation and non-combustibility and is lightweight and has sufficient mechanical strength by foaming. We studied diligently to obtain. As a result, the present inventors used an inorganic filler as a base material, added a vinyl chloride resin thereto, and further added additives such as a foaming agent and an organic solvent and kneaded,
By heating and foaming, it has been found that even if a large amount of the inorganic filler is mainly contained, high foaming can be achieved with a stable and uniform cell structure, and heat insulation and nonflammability can be imparted. Such foams are lightweight and have excellent heat insulation, water resistance, sound absorption, mechanical strength, and the like. In addition, the addition of a metal compound allows the vinyl chloride film in the composition to be uniform. It has been found that not only molding at the curing stage after foaming but also press molding by reheating after curing can be performed very easily and favorably. The present invention has been completed from such a viewpoint.

[0005]

That is, the present invention relates to a method for producing a polyvinyl chloride resin comprising 5 to 50 parts by weight of a vinyl chloride resin and 50 to 50 parts by weight of an inorganic filler.
It is an object of the present invention to provide a method for producing an inorganic foam, characterized in that 32 to 120 parts by weight of an additive is added to 95 parts by weight, kneaded to form a compound, and the compound is heated and foamed in a mold. Here, the additive preferably comprises a foaming agent and an organic solvent.
More preferably, the amount is 30 parts by weight and 30 to 100 parts by weight of the organic solvent. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing an inorganic foam according to the present invention, an inorganic filler, a vinyl chloride resin and an additive are used as materials. Examples of the inorganic filler include hydroxides such as aluminum hydroxide, magnesium hydroxide and calcium hydroxide, carbonate compounds such as calcium carbonate and magnesium carbonate, and compounds having crystal water such as gypsum and aluminum sulfate. Compounds such as asbestos, talc, benite, clay, or silicates,
Serpentine is also included. These compounds can be used alone or in combination of two or more.

The particle size of the inorganic filler is determined by the absorption of the plasticizer.
While it is an important factor in determining the amount of oil,
There are preferred values depending on the type. For example, talc @ Mg
_ThreeH _Two(SiO_Three)_Four｝ Improves its dispersibility
For this reason, it passes 90% or more through a 150-mesh sieve.
The above fineness is preferable. In calcium carbonate,
Reacts with chlorine generated by the combustion of vinyl chloride resin
Detoxification and adhesion between vinyl chloride resin and plasticizer
Required in 70-200 mesh to improve
Preferably a cloth. Water to improve non-combustibility
When using aluminum oxide, 300 mesh or less
It is preferred to use the following: In the present invention, the above
50 to 95 parts by weight, preferably based on an inorganic filler, preferably
Is 52 to 90 parts by weight, more preferably 54 to 80 parts by weight
Used.

The vinyl chloride resin used in the present invention may be any polymer having vinyl chloride as the main component of the monomer, and general vinyl chloride resins can be widely used. Its properties are also used without particular limitation,
From the viewpoint of foam production, it is preferable that the resin is a so-called paste resin having a required distribution with a particle size that passes through a 325 mesh sieve. This is because such a paste resin can easily maintain the intimacy between the oil absorption of the plasticizer and the inorganic filler. The mixing ratio of the vinyl chloride resin to the inorganic filler is 5 to 50 parts by weight, preferably 10 to 48 parts by weight, more preferably 20 to 50 parts by weight of the vinyl chloride resin with respect to 50 to 95 parts by weight of the inorganic filler.
４６46 parts by weight. If the compounding ratio of the vinyl chloride resin is less than 5 parts by weight, it is not preferable because sufficient foaming is difficult to be performed, mechanical strength is not obtained, and the resin becomes brittle. Conversely, if the compounding ratio of the vinyl chloride resin exceeds 50 parts by weight, it is difficult to obtain a non-flammable and heat-resistant foam which is one of the objects of the present invention, which is not preferable.

In the inorganic foam of the present invention, a foaming agent, an organic solvent, a plasticizer, a metal, a metal compound, a flame retardant, a ceramic, a mineral, and the like are used as additives. In the present invention,
Carbon black can also be used as one of the additives, and can be widely used without any particular limitation on its properties and the like. If the compounding ratio is too small even if carbon black is added, the resulting inorganic foam will not have sufficient antistatic properties and radio wave absorption. Conversely, if the compounding ratio of carbon black is too large, the mechanical strength will decrease. It is difficult to obtain an excellent foam.

Examples of the foaming agent include inorganic foaming agents such as azodicarbonamide, azobisisobutylnitrile, dinitrosopentatetramine, P-toluenesulfonylhydrazide, and P, P'-oxybis (benzenesulfonylhydrazide) which are organic foaming agents. Certain sodium bicarbonate, ammonium chloride, and the like. As the organic solvent, generally used ones can be widely used.
Xylene and the like are preferred. Examples of the plasticizer include dimethyl phthalate, dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, diisonolyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dicyclohexyl phthalate, tricresyl phosphate, tributyl phosphate, tris (2-ethylhexyl) ) Phosphate, tri (chloroethyl) phosphate, trischloropropyl phosphate, ortho-diphenyl phosphate, tris (isopropylphenyl) phosphate, cresyl diphenyl phosphate, dioctyl azelate, and paraffin chloride.

[0011] Metals that are conductive substances include aluminum (Al), copper (Cu), lead (Pb), tin (Sn),
Iron (Fe), silver (Ag), and the like. Examples of the metal compound include aluminum oxide, iron oxide, zinc oxide, barium sulfate, titanium oxide, magnesium oxide and the like. As a flame retardant, tetrabromobisphenol A,
2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, hexabromobenzene, tris (2
3-dibrimopropyl) isocyanurate, 2,2-bis (4-hydroxyethoxy-3,5-dibromophenyl) propane, ammonium decabromodiphenyl oxide phosphate, tricresyl phosphate, triethyl phosphate, tris (β-chloroethyl ) Phosphate, trischloroethylphosphate, trisdichloropropylphosphate, cresyldiphenylphosphate, xylenyldiphenylphosphate, red phosphorus, tin oxide, antimony trioxide, zirconium hydroxide, barium metaborate, aluminum hydroxide, magnesium hydroxide, etc. Is mentioned. Examples of the ceramic include yttrium oxide, zirconia, silicon carbide, aluminum nitride and the like. Minerals include gallium, zirconium,
Tourmaline and the like.

[0012] The amount of the above-mentioned additives is from 50 to 50% of inorganic filler.
32 to 120 parts by weight, preferably 40 to 100 parts by weight, more preferably 4 to 100 parts by weight, based on 95 parts by weight.
5 to 95 parts by weight are blended. Of these various additives,
Primarily used additives are blowing agents and organic solvents. The amount of the foaming agent is not particularly limited, but is preferably 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 50 to 95 parts by weight of the inorganic filler. It is preferable that the blending ratio of the foaming agent is within the above range, since a stable foam can be obtained. Also, the amount of the organic solvent is not particularly limited, but is preferably 30 to 100 parts by weight, more preferably 4 to 95 parts by weight based on the inorganic filler.
0 to 90 parts by weight are blended.

Of the above additives, metals, metal compounds, flame retardants, ceramics, and minerals are each optionally used as needed, and the amounts thereof are not particularly limited. In the present invention, in addition to the above additives, additives such as a heat stabilizer, an ultraviolet absorber, an antioxidant, a reinforcing filler, a nonflammable dye and a fungicide may be used as needed. it can.

Next, the manufacturing process of the present invention using the above materials will be described. The present invention relates to a vinyl chloride resin 5 to 50.
32 to 120 parts by weight of an additive are added to 50 parts by weight of the inorganic filler and 50 to 95 parts by weight of the inorganic filler, and kneaded to form a compound, and the compound is heated and foamed in a mold. In the production method of the present invention, a vinyl chloride resin, calcium carbonate,
With inorganic fillers such as talc and asbestos as main components,
The above-mentioned foaming agent among the additives is mixed. An appropriate amount of the above organic solvent is added to the mixture, and the mixture is mixed with a kneader or the like. At this time, the temperature of the compound in the mixer preferably does not exceed 0 ° C to 50 ° C so that the vinyl chloride resin does not gel and the blowing agent does not foam.

The compound is filled in a mold and heated to preferably 140 to 170 ° C. to foam the blowing agent and at the same time gel the vinyl chloride resin. At this time, the mold is pressurized with a press or the like so that the contents in the mold are not scattered by foaming of the foaming agent and evaporation of the organic solvent, and the reaction is allowed to proceed while maintaining airtightness. As a result, the inside of the mold
By increasing the pressure, the gas generated by foaming of the foaming agent is uniformly diffused into the gelled vinyl chloride resin and the inorganic filler. After the reaction is sufficiently performed, the mold is cooled to room temperature while maintaining the airtightness, and the product is taken out of the mold by gradually reducing the pressure of the press. At this point, the product is 30-40% of the desired expansion ratio (primary expansion). Next, the product is again subjected to 90 ° C. in a warm air circulation device such as an oven under normal pressure.
C. to 120.degree. C. and a desired expansion ratio of 5 to 20.
Inflate to double (secondary foaming). Then, when expanded, the temperature is lowered again to room temperature and cured. In addition,
The expansion ratio is a value indicating how many times the volume of the obtained foam becomes larger than the initial volume. Thereafter, the product is gradually heated to remove the organic solvent, and a product as a foam is obtained.

On the other hand, when a plasticizer is used, it is kneaded in a kneader or the like at a low speed in a range of ordinary temperature to 0 ° C. and ordinary pressure in addition to the above-mentioned mixed powder. Furthermore, a non-combustibility improving filler having a hydroxide such as aluminum hydroxide or water of crystallization is added to the compound and kneaded. A plasticizer is further added to the obtained compound to obtain a paste-like compound. Thereafter, the compound is heated in a mold and heated to at least a temperature at which the foaming agent is decomposed or vaporized and a temperature at which the vinyl chloride resin gels. As a result, the vinyl chloride resin dissolves in the solvent (plasticizer), wraps the fine particles of the inorganic filler without corners, adheres to the fine particles, and bonds the fine particles to each other.

[0017] The foam obtained by the production method of the present invention, while being a vinyl chloride resin with a small blending ratio, becomes stronger as the viscosity of the film increases. Generally, when the amount of the inorganic filler becomes about 90%, the thermoplasticity is lost, but the foam produced by the method of the present invention has complete thermoplasticity. Therefore, even at the stage of becoming a product as a foam, in a state where it has not yet been cured, it is possible to very easily slice or the like as necessary and easily mold to a desired size. . In addition, the foam in its soft state can be easily deformed and cured to the shape according to the mold only by being placed on a specific mold, and a molded article having an uneven three-dimensional shape can be easily formed. It is possible. On the other hand, the foam once molded into a plate or the like is easily plasticized from the properties of the vinyl chloride resin by reheating later, so that hot press molding is possible and post-processing can be performed. It also has a characteristic.

Further, since the foam obtained by the production method of the present invention is formed by closed cells mainly composed of an inorganic filler, it is lightweight and has heat insulation, sound absorption and water resistance, and It also has mechanical strength, dimensional stability, non-combustibility, etc. Therefore, it is possible to use it as it is, to use it by mixing a pigment or a dye in the foam in advance, or to use the outer surface after coloring such as painting. Furthermore, even if the foam obtained by the present invention is heated to a high temperature due to a fire or the like, the generation of hydrogen chloride gas is suppressed to a very small amount, so that the danger due to the generation of toxic gas is extremely small. It is extremely useful as a building material. Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0019]

EXAMPLE 1 40 parts by weight of vinyl chloride resin, 30 parts by weight of calcium carbonate as an inorganic filler, 15 parts by weight of talc, 15 parts by weight of serpentine, 4 parts by weight of azobisisobutylnitrile as a blowing agent, dinitrosopentatetramine 4 parts by weight and 4 parts by weight of a urea-based foaming aid as another additive were put in a kneader and mixed for 5 minutes. Next, 70 parts by weight of toluene as an organic solvent was gradually added and kneaded for 1 hour. In a pressurized state, the compound obtained by kneading was filled in a mold without gaps, the upper part was covered, and pressurized by a press. In this state, heating was performed to gel the vinyl chloride resin, and at the same time, the blowing agent was decomposed.

After sufficient gelation and decomposition, the mold was cooled down to room temperature while being pressurized, and the product was taken out. The product was heated again at normal pressure and expanded to the required dimensions.
After reaching the predetermined size, the mixture is once cooled to room temperature and heated again gradually, and the toluene is evaporated from the product and completely removed. Thus, the inorganic foam of the present invention was obtained. The obtained foam could be sliced very easily, and could be easily formed into desired dimensions. Further, the foam was easily plasticized due to the characteristics of the vinyl chloride resin by reheating, and post-processing by hot press molding could be performed.

[0021]

According to the method for producing an inorganic foam of the present invention, an inorganic foam having a stable and uniform cell structure containing a large amount of an inorganic filler can be efficiently and stably produced. it can. In addition, the inorganic foam obtained by the present invention has a stable and uniform cell structure mainly containing an inorganic filler, so that it is lightweight and has heat insulation, water resistance, sound absorption, mechanical strength, nonflammability, etc. Is also an excellent foam. Furthermore, the addition of a metal compound and the like makes the vinyl chloride film in the composition uniform and reinforced, so that not only molding at the curing stage after foaming but also press molding by reheating after curing is very easily and favorably performed. I can do it. Therefore, it can be used not only as a heat insulating material but also as a building material, a vehicle interior material, a component material of various devices, and the like.

Claims (2)

[Claims] 1. A compound is prepared by adding 32 to 120 parts by weight of an additive to 5 to 50 parts by weight of a vinyl chloride resin and 50 to 95 parts by weight of an inorganic filler and kneading to form a compound. The compound is heated and foamed in a mold. A method for producing an inorganic foam, comprising: 2. The method for producing an inorganic foam according to claim 1, wherein said additive comprises a foaming agent and an organic solvent.