JP2000000908A - Plastic foamed composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat insulating material not absorbing moisture and not lowering heat insulating properties even if used over a long period of time at a place where there is a temp. gradient. SOLUTION: A plastic skin 1 with a thickness of 1.0 mm or more is formed on a crosslinked foam 2 of low density polyolefin with a density of 0.2 g/cc or less having uniform fine air bubbles and the skin and the foam layer are bonded with strength higher than that of the foam without providing a skin material phase of wall stone like patterns and voids on the foam layer to form a foam composite having hygroscopic resistance and not lowering heat insulating properties even if used over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to claim 1.

[0002] The present invention relates to a heat insulating material, a floating material, and a cushion material.

[Prior Art] Foamed plastic is made of a material having a low thermal conductivity, is an aggregate of small air bubbles, and has a very large volume occupied by gas. It is widely and widely used as a floating material and cushioning material. The biggest disadvantage of insulation is that when placed in a high humidity place, it absorbs moisture and the insulation is reduced, but it can not be used only in low humidity places, there is no good way to improve this For this reason, the world is wasting enormous energy today. Foamed plastic is a hydrophobic material, and has less hygroscopicity than hydrophilic materials such as glass wool, but still absorbs moisture when placed in high humidity places. This is presumably because the foam film of the foamed plastic is thin, and the thickness is uneven and there is a very thin portion. Since the heat insulating material is used for a long time in a place having a temperature gradient, this is further promoted, and the increase in energy usage due to moisture absorption of the heat insulating material cannot be discarded.

[0004] In order to prevent moisture absorption of the foamed plastic and not to lower the heat insulating property, it has been practiced to wrap the foamed plastic with asphalt paper for use. However, asphalt paper does not have sufficient moisture absorption resistance, it is difficult to cover the entire surface of the foam without any gaps, and it is brittle at low temperatures and easily cracked, which is a problem particularly in Japan where earthquakes are frequent. Even in a freezing warehouse, etc., even if the insulation is wrapped with asphalt paper and efforts are made to keep the temperature constant and prevent moisture absorption, the power consumption will be 20 times longer than the power consumption at the time of establishment.
The percentage also rises. Eliminating the 20% rise is an urgent task for energy conservation.

[0005] There is a method of providing a plastic skin having better moisture absorption resistance than asphalt on a plastic foam. As the material for preventing moisture absorption of the plastic foam, plastic is the best in view of its effect, processability, cost and the like, and no other material is conceivable. In addition, when a plastic skin is formed, the mechanical properties are also improved, which is preferable when used as a cushioning material or a floating material. One of the methods is a method in which a hollow molded body is formed by rotational molding, and urethane is injected into the hollow molded body and foamed. This method is much more excellent in the moisture absorption resistance of the foam than the method using asphalt. However, this technique involves two steps of rotational molding and urethane injection, requires two types of molds, is expensive, and has a problem in bonding the skin to the foam. In the composite having the sandwich structure, sufficient adhesion between the skin and the foam is an essential requirement. If the adhesion is insufficient, neither moisture absorption resistance nor mechanical properties such as bending strength can be increased.

[0006] Another method is a method in which a hollow molded body of plastic is made by blow molding, pre-expanded beads such as polystyrene are put in the hollow molded article, and steam is fed into this to integrate the beads. This technique requires three steps of blow molding, production of a pre-foamed body, and integration, and is costly. In addition, the temperature at which the beads are integrated cannot be increased. Insufficient, neither moisture absorption resistance nor mechanical properties.

There is a technique in which powdered plastic and foamable granular material are simultaneously placed in a mold and heated while rotating to obtain a composite having a skin. This technique can be molded in one step, is inexpensive, and has excellent adhesion between the skin and the foam. Rotational molding is the best technique for forming a skin over the entire surface.

[0008] This one is a patent of one of the inventors USP
At 3.814.778, powdered plastic and foamable granules are placed in a mold and heated while rotating or applying an impact to obtain a composite of skin and foam. A skin of uniform thickness is obtained, and the skin and foam are
It is stated that it is glued. This patent relates to a molded product having excellent strength such as a pallet, and does not consider a heat insulating material that does not absorb moisture, and has a heat insulating property, a phase of a stone wall pattern-like skin material in a foam layer, a void, and a foam and a foam layer. Necessary requirements for a heat insulating material that does not absorb moisture, such as adhesiveness and a method using a large amount of a foaming agent, are not described.

US Pat. No. 3,914,361 is also one of the inventor's patents and describes a method for producing a composite comprising a skin and a foam. This method is a method of heating with steam, and uses packing for a mold. When packing is used, the gas in the mold does not escape, so voids are easily formed. In this patent, a valve is attached to the mold. This patent is a method using steam heating, which is not suitable for a method of manufacturing a heat insulating material that does not absorb moisture, because the foam absorbs moisture and suppresses foaming. Also, this patent does not describe a heat insulating material that does not absorb moisture.

[0010] Japanese Patent Application Laid-Open No. 1-253433 describes a method for producing a foamed composite in which the skin is crosslinked. When the skin is crosslinked, foaming is suppressed, and the molded body tends to be deformed and voids are apt to be formed. This patent mentions, but is limited to, insulation, and this method is the best insulation, with a foam density of 0.035 g / c.
This is a method that does not work for c. In addition, this patent also describes a heat insulating material which does not absorb moisture, a heat insulating property, a stone wall-like skin material phase in a foam layer, a void, an adhesive property between a skin and a foam, a method using a large amount of a foaming agent, and the like. There is not enough description.

Japanese Patent Application Laid-Open No. 8-57878 is also an application filed by one of the inventors and describes a method for producing a foam having a skin. In this technique, the mold is mounted on a rotating shaft by tilting it uniaxially. However, it is difficult to form a sphere or a cube by uniaxial rotation, and it is difficult for the skin to have a uniform thickness. And there is no notation of the heat insulating material which does not absorb moisture in this patent.

[0012] The present invention is a composite in which the cross-linked foam of polyolefin is entirely covered with a plastic skin, has excellent moisture absorption resistance, and can be used for a long time in a high humidity place. An object of the present invention is to obtain an energy-saving foamed composite that does not absorb moisture and does not deteriorate in heat insulation.

[Embodiment of the Invention] Polyolefin is a material that hardly absorbs moisture, and this foam has less decrease in heat insulation due to moisture absorption than other plastic foams. Polyolefins are difficult to make into low-density foams without cross-linking and cross-link to improve their viscoelasticity and expand. Therefore, a foam having uniform and fine closed cells can be stably obtained, and since this foam has heat resistance and stable bubbles even at 200 ° C., a foam having a skin can be obtained in one step. As described above, plastic foams having excellent heat insulating properties and having a skin that does not absorb moisture are not considered other than crosslinked foams of polyolefin.

The foam of the present invention is a crosslinked polyolefin foam having a density of 0.2 g / cc or less, preferably 0.1 g / cc or less, more preferably 0.05 g / cc or less.
It is as follows. It is well known that foams having a density near 0.035 g / cc have the best thermal insulation. In the present invention,
The reason why the density of the foam is set to 0.2 g / cc or less is as follows.
Foams of 2 g / cc or more have spherical cells, insufficient heat insulation, and a small amount of a foaming agent. Therefore, heat generated due to decomposition of the foaming agent during molding is insufficient, and voids are formed in the mold. Is easy to do.

The foam of the present invention is a uniform layer as shown in FIG. 1, and is composed of only an extremely thin film and independent small bubbles surrounded by the film, and has excellent heat insulating properties and moisture resistance. It is. The uniform layer and the absence of foreign matter make the heat insulating property and the moisture absorption resistance good. In the present invention, the powdered plastic and the crosslinked expandable granules are simultaneously placed in a mold and heated while rotating. Therefore, powdered plastic may adhere to the surface of the granular material and foam, and as a result,
In the foamed plastic layer, a powdered plastic as shown in FIG. 2 sometimes forms a stone wall pattern-like phase. And
Since the stone wall pattern-like phase is much thicker than the foamed plastic film, the formation of this phase lowers the heat insulating property. In addition, when such a foreign phase is present in the foamed layer, moisture easily passes through the interface and affects the moisture absorption resistance. Therefore, in the present technology, a foam having no such phase is an essential requirement. . The existence of the stone wall pattern phase becomes clear when, for example, powdered plastic and foamable granules are molded in different colors. Then, even if it looks like a thin phase, since it is thicker than the foam film, both the heat insulating property and the moisture absorption resistance decrease.

In the foam of the present invention, since the crosslinked expandable granules are heated in a mold in an assembled state, voids having a diameter of several mm are easily formed as shown in FIG. And if there is this void, the heat insulating properties will naturally deteriorate. In the present invention, in order to suppress the formation of voids, a large amount of a foaming agent is used and molding is performed with a high molding pressure in a mold as compared with molding of a crosslinked polyethylene foam at normal pressure.

The foam of the present invention needs to be uniform and fine cells from the viewpoint of heat insulation. The cell diameter is 1.2 mm.
Or less, preferably 0.8 mm or less, more preferably 0.4 mm or less. Even a low-density foam having a cell diameter of 1.2 mm or more has poor heat insulation due to convection of gas in the cells.

The skin of the present invention is obtained by integrally forming a powder of a thermoplastic resin such as polyolefin, nylon or ABS by rotational molding. Preferred are polyolefins because of their low moisture absorption, and more preferred are high-density polyethylenes. High-density polyethylene has excellent adhesion to the foam of the present application. The skin of the present invention has a thickness of 1.0
If the skin is not less than 1.0 mm and does not reach 1.0 mm, the heat insulating layer absorbs moisture little by little to reduce the heat insulating property.
The thickness of the surface wave is preferably 1.5 mm or more, and more preferably 2.0 mm or more. A skin thicker than 5 mm is not preferable because heat escapes through the skin phase, resulting in poor heat insulation of the molded body. The skin of the present invention needs to be of uniform thickness. With the uniform thickness in the present invention,
The ratio of the minimum thickness of the skin to the standard thickness is 以上 or more. If a thinner part having a minimum thickness is formed, the hygroscopicity increases and the mechanical properties deteriorate. In the present invention, the epidermis may also be foamed, which has a spherical cell density of 0.25.
Limited to foams of g / cc or more.

Since the foamed composite of the present invention is a sandwich structure, it is essential that the skin and the foam be well adhered to each other. Also, mechanical properties such as bending strength are improved. The foam of the present invention is a semi-rigid, low-density cross-linked foam of polyolefin. Therefore, this foam does not have high compressive strength, so it is necessary to adhere firmly to a durable skin to make a strong composite, and the adhesive strength must be higher than the strength of the foam. It is. Composites of skin and foam with poor adhesion are poor in strength because they absorb moisture even with slight flaws and are not supported by the presence of the foam in bending, compressive or impact strength. Since the foamed composite of the present invention is molded at a high molding pressure, the adhesion between the skin and the foam is sufficient, and the flexural strength, impact resistance and the like are good. Therefore, the skin can be made slightly thinner, and from this point, a composite having excellent heat insulating properties can be obtained.

In short, an energy-saving heat insulating material which is excellent in heat insulating properties and does not absorb moisture even when placed in a humid place for a long time is made of a thermoplastic material having a thickness of 1 mm or more and a minimum thickness of the skin. At least 標準 of the standard thickness, the entire surface of the foam is covered with this skin, and the foam is a crosslinked foam of polyolefin having a cell diameter of 1.2 mm or less, and a density of 0.2 g / cc or less. The foamed layer is a composite having no phase of a stone wall pattern-like skin material, no voids, and an adhesive strength between the skin and the foam that is equal to or greater than the strength of the foam. Such a composite does not absorb moisture for as long as 50 years of the service life of a building for the first time as a heat insulating material having excellent heat insulating properties, and therefore, it is possible to suppress an increase in the use of energy without lowering the heat insulating properties.

The crosslinked expandable granular material of the present invention is obtained by crosslinking a polyolefin in which a crosslinking agent and a blowing agent are mixed, or a polyolefin in which a blowing agent is mixed by ionizing radiation. This crosslinked foam has good heat resistance, stable bubbles even at a temperature of 190 ° C. at which the foaming agent decomposes, and enables production of a foamed composite having a skin, but has a strong property of expanding, so that the Foamed grains partially penetrate and locally thin the epidermis, causing a large amount of burrs. In addition, since powdered plastic is adhered to the surface of the crosslinked expandable granules and foamed, the composite becomes a composite having a stone wall pattern-like skin material, which may cause voids.

The present inventors have studied a method for producing a composite having no such disadvantages, and have found that the storage elastic modulus of the powdered plastic used for the skin at 190 ° C. at an angular frequency of 1 (rad / S) is 1 × 10 4. It has been found that this object is achieved by using a material of ³ (Pa) or more. Here, the storage elastic modulus means that when a periodic (sinusoidal) stress is applied to a sample, the corresponding strain also changes periodically (sinusoidally), but the phase shifts. When the stress is divided by the strain, the elastic modulus is obtained. When this is expressed vectorwise or complexly, G ^* =
G '+ iG ". The real part of the elastic modulus is called the storage elastic modulus, and the imaginary part is called the loss elastic modulus. These names are related to the storage and loss of energy (dissipated as heat), and therefore have this name. The method for measuring the storage modulus is, for example, a cone plate rheometer, in which the disc and the cone face each other (with the vertex of the cone facing the center of the disc).
Between which a viscoelastic liquid or melt is filled. By vibrating a disk periodically, the viscoelastic constant (for example,
G ′, G ″). For example, the storage elastic modulus at an angular frequency of 1 (rad / S) at 190 ° C. is 4 × 10
^{When the} material of ² (Pa) is used as the skin material, the storage elastic modulus is too low, so that the composite of the present invention cannot be obtained.

The powdered plastic of the present invention is a thermoplastic resin powder having a storage elastic modulus of 1 × 10 ³ (Pa) or more, and a preferable storage elastic modulus is 5 × 10 ³ (Pa) or more.
Preferably it is at least 1 × 10 ⁴ (Pa). A resin with a low storage modulus that is compatible with a resin with a large storage modulus,
For example, a medium density polyethylene or the like may be mixed and used, whereby the impact resistance is improved. In some cases, low-density polyethylene is mixed with high-density polyethylene to improve the elastic modulus. Another reason to select a storage modulus in this range is to increase the ratio of the minimum thickness to the average thickness and make it more uniform. In addition, an inorganic filler, glass fiber, or the like may be mixed into the skin to reinforce the skin. Then, two kinds of powders having different particle diameters can be used for the skin to form a two-layered skin.

In the present invention, voids may be formed in the foamed layer. For this reason, a large amount of a foaming agent is used, and the inside of the mold is pressurized and molded. In normal-pressure foaming of a crosslinked foam of polyethylene, a compound containing 10 PHR of ADCA usually expands about 20 times. This almost completely uses the gas generation amount of ADCA of 230 cc / g.
(Refer to Simultaneous Decomposition Method of Low Density Polyethylene, Vol. 34, No. 2 of High Polymer Papers.) The method of the present application is a method in which the inside of a mold is pressurized to eliminate voids, and the amount of a foaming agent used. Must be used in an amount of at least 150%, preferably at least 180%, more preferably at least 210%. And by doing so, a foamed composite without voids is obtained.

No. 1 of the first embodiment. 1 is 1000cc mold
It is. And 98 g of powdered plastic and 40 g of foamed compound are used for this. Since the density of the powdered material is 0.96 g / cc, this volume is 98 / 0.9.
6 = 102 cc. The volume of polyethylene contained in the compound is 40 × 100/130 / 0.9.
2 = 33 cc. (The volume of the decomposition residue of the foaming agent is ignored.) Therefore, the volume that can be expanded and expanded in the mold is 1000.
-102-33 = 865 cc. 40 g of the foaming compound is used for this, and the ADCA contained therein is 40 × 30/130 = 9.2 g, and the gas emitted therefrom is 9.2 × 230 = 2116 cc. Therefore, 211
6/865 = 245% of blowing agent is used. For this reason, when the foaming agent is decomposed, the inside of the mold is in a pressurized state, and this molded body has no void.

The crosslinked expandable granules of the present invention can be obtained by mixing polyethylene, polypropylene, EV
A polyolefin such as A, which has a larger grain size than powdered plastic, and has a particle size of at least 3 times, preferably at least 10 times as large as that of powdered plastic, and has a side of 0.3 or more.
It is a granular material of 10 to 10 mm, and preferably 1 to 5 mm. It is preferable to use a shape such as a sphere, a rod, or a cube that is easily moved by rotation in a mold. Further, if an inorganic powder such as talc or clay is adhered to the surface of the granular material and used, the electrification due to friction of the material is prevented, and the skin material is not mixed into the foamed layer.

In some cases, the crosslinked foamable material is formed into a spherical or rod-like shape, and a non-foamed or slightly foamed material is coated as the foamable material. When this material is placed in a mold and foamed, the foamed layer does not foam or a slightly foamed section is formed, and this section becomes a strength member, resulting in a composite having excellent mechanical strength.

The foaming granular material of the present invention comprises
Blowing agents such as azodicarbonamide and dinitrosopentamethylene latramine are used. The amount of the foaming agent is 5 PHR or more and 50 PHR or less, and preferably 10 PHR or more. And the foaming agent is 5PHR
In the following, heat generation due to decomposition of the foaming agent is small, and an unfoamed portion is easily formed, and heat insulation is not sufficient. 50P foaming agent
If the HR or more is added, the amount of gas to be foamed is too large and the foam does not become a closed cell foam. A foaming aid such as zinc stearate may be used together with the foaming agent to lower the foaming temperature.

The crosslinking agent for the expandable granules of the present invention is an organic peroxide such as cumyl peroxide, 2,5-methyl 2,5-tert-butyl peroxyhexane. And, the addition amount of the crosslinking agent is 0.2 PHR or more,
R or less, preferably 0.5 PHR or more, 1.0 PHR
There are: In addition, a crosslinking aid having two or more reactive double bonds in the molecule, such as 1,2 polybutadiene, triallyl cyanurate, triallyl isocyanurate, may be used together with the crosslinking agent. The crosslinker breaks down prior to foaming to crosslink the polyolefin, improving viscoelasticity and making foaming suitable. The gel fraction of the finished foam is usually 3
0 to 80%. Here, the gel fraction is a percentage obtained by immersion in 90 ° C. toluene and excluding the sol content. The decomposition temperature of the cross-linking agent is about 160 ° C., and processing such as kneading and extrusion of the compound containing the cross-linking agent is performed at about 130 ° C.

The mold used in the present invention is made of a plate material or a casting made of a metal material having good heat conductivity, such as iron, aluminum, and brass, and is usually divided into two or a side wall and upper and lower lids. The thickness of the mold is 3 to 15 mm. The mold is usually provided with one or several small holes having a diameter of 1 to 10 mm for allowing the air inside the mold to escape during foaming. And put a heat-resistant plastic pipe in this small hole,
One end goes out and the other end is located as close to the center of the mold as possible so that the powdered plastic does not come out. A Teflon tape, a perforated Teflon tape, or the like may be wrapped around the end of the pipe near the center of the mold to prevent the escape of the plastic powder. When rotational molding is performed using a mold having no small holes, voids are likely to be generated in the foamed phase. In addition, since voids are easily formed when packing is used, packing is not usually used for a mold.

The rotation of the mold is biaxial rotation, swing rotation, and the like. Uniaxial rotation is not used because a thin skin is formed. The rotation is usually 1 to 20 rpm and is a slow rotation such that no centrifugal force is applied to the material placed in the mold. This rotation normally uses both forward rotation and reverse rotation.

The heating is performed by hot air, direct fire or the like. Heating by steam is not used because steam enters the mold, absorbs the resin, and lowers the expansion ratio.
The heating is performed at a temperature of the mold of 170 to 300 ° C., preferably 190 to 250 ° C., and the heating time is 10 to 50 minutes. After heating, the mold is immersed in water or rapidly cooled by a shower, and the foam composite is removed from the mold. The skin is rapidly cured by water cooling, but at this time, the foaming phase in the center is molten, and the skin is hardened while applying foaming pressure, so the surface is smooth and beautiful, as the shape of the mold, over time The molded product does not shrink.
In addition, if it is left in the air and gradually cooled, the impact resistance is reduced.

In this way, a foamed composite is produced, and the plastic powder and the foamable granules present in the mold are put in small amounts at least 10% more than the inner volume of the mold. Therefore, the position in the mold is shifted by the rotation of the mold. Then, since the mold is heated from the outside, first, plastic powder of small particles melts and adheres to the inner surface of the mold to form a skin. Next, expandable granules of large particles adhere to the inside of the epidermis, and when further heated, the crosslinking agent and the foaming agent decompose and expand to fill the mold. At this time, the air existing in the mold gathers at the center of the mold and escapes from the plastic pipe inserted into the mold. The particle size of the powdered plastic is usually 0.1 mm or less, and the crosslinked expandable granular material is about 3 mm. Therefore,
The particle size of the granular material is 30 times that of the powdered plastic, and its volume and weight are 27,000 times its cube. Therefore, the temperature rise is slow, the energy of the movement is large, the adhesion to the mold is delayed, and the two are clearly separated to form a skin and a foam layer.

The skin of the foamed composite of the present invention is formed integrally by rotational molding, has no welding line, and is firmly bonded to the foam, and therefore has excellent moisture absorption resistance and has been used for many years. Even if it does, heat insulation does not decrease. The thickness of the foam layer of the present invention is usually 10 to 100 mm, and if it is 10 mm or less, the separation between the skin and the foam layer tends to be insufficient. 100m
Although it is possible to form a layer having a thickness of not less than m, it is rare that the thickness is not less than 100 mm.

The foam composite of the present invention is prepared by heating the skin and expandable particles at a temperature considerably higher than the melting point in a mold. In addition, since the pressure in the mold is increased and the molding is performed, the skin and the foam layer are melted in the mold and pressed and adhered firmly. The body has high bending strength and impact strength and is hard to absorb moisture. Therefore, even if it is used for a long time in a place with high humidity, the heat insulating property does not decrease. From the foamed composite of the present invention, a joined body of a skin and a foamed layer having a thickness of 5 mm is cut out, and the size is, for example, 10 mm in width and 100 m in length.
m, insert a knife from one end, separate the half skin and foam, and pull the skin and foam in the direction of 180 degrees so that they can be separated. The body cuts. The foam of the present invention is a cross-linked foam of polyolefin, which is elastic and shock absorbing. Therefore, the one using a durable skin material is extremely durable and does not break by impact. The foamed composite of the present invention is also characterized by having a durable skin on its side, which is the bending and compressive strength,
It contributes to high impact strength.

In the present invention, a composite having a skin, a foam layer under the skin, and a gas layer in the middle can be produced. The molded body has excellent elasticity, is lightweight, and is used as a cushion material, a float, and the like. In the present invention, industrial waste can be used as the material for the skin and the material of the crosslinked foamed granular material. Inorganic fillers and the like can be mixed in the skin material and the crosslinked expandable granular material of the present invention. Therefore, even if a small amount of mud or sand enters using plastics of industrial waste, it does not affect the molding. In addition, the foaming of the present invention is based on crosslinked foamable granules, and a large number of small particles foam in an aggregated state to form a foamed layer. Therefore, for example, even if a small amount of particles having poor foamability are mixed, it is fine. In the present invention, it is possible to produce a composite having a skin, a foam layer underneath, and a granular material such as plastic, rubber, wood, or the like, or a granular material obtained by crushing the foam composite in the middle. This molded body is placed in a mold with powdered plastic, cross-linked expandable granules, and plastic, rubber, wood, and expanded composites having a larger shape than the cross-linked expandable granules, and heated while rotating. It is a molded article that is durable and has excellent heat insulation properties, and is suitable for use as waste of plastics, rubber, wood, and the foam composite.
And with this technology, waste of cross-linked polyethylene, FRP, which cannot be used in other ways as plastic waste,
Waste can also be used. In the present invention, a flame retardant can be added to both sides of the skin and the foam layer and molded to obtain a molded article having flame retardancy.

In the present invention, a metal fitting is attached to the mold by making a small hole, and bolts, nuts, pipes, hooks and the like can be embedded in the foam composite. For example, in order to embed a bolt, the bolt is inserted inside the mold, the bolt is passed through a small hole of the mold, and a nut is attached to the tip of the bolt to form the bolt. The heat is transferred from the nut outside the mold to the bolt and heated to form a skin on the surface of the bolt, and this skin is bonded to the skin or foam layer of the foam composite, thereby firmly fixing the bolt. Therefore, there is a part of the metal fitting outside the mold,
From there it is necessary to supply heat to the fittings. And with this metal fitting, a strong connection between the composite molded bodies or other objects can be easily made.

When a skin perpendicular to the board is made using a metal pipe on the foam board, this skin is connected to the upper and lower skins of the board and is well bonded to the foam phase. Significantly improves the compression resistance, impact resistance, and bending resistance of In the present invention, for example, 1000 × 1000 × 50 mm
When the foamed board is made, the product of the present invention forms a strong integral skin over the entire surface. The portion near the edge has the skin on the side, but is strong, but is weak against compression near the center. If nine holes having a diameter of 25 mm are formed in the plate at intervals of 250 mm and a skin is provided in these holes, the compression resistance and impact resistance at the center of the plate are remarkably improved, and the whole plate becomes strong. For example, the increase in compressive strength per small hole having a skin thickness of 3 mm and a diameter of 25 mm can be as much as 300 kg. Therefore, the thickness of the skin can be reduced, and the weight can be reduced. And
When used for thermal insulation, these holes are filled. As a filling, a foamed composite with a skin is best.

As described above, the foamed composite of the present invention can be provided with a metal fitting, and a hole having a skin having a thickness of 1.0 mm or more can be formed by using the metal fitting. When provided, even if water or air is passed through the hole for a long period of time, the foam does not absorb water and moisture, and the heat insulating property does not decrease. In order not to absorb moisture, the skin around the hole is 1.0 mm or more, the minimum thickness is 0.5 mm or more, and this skin is bonded to at least one skin of the molded body, and It is necessary to adhere to the foam and to have an adhesive strength not less than the strength of the foam. Using this hole, a metal fitting can be attached, a foam board can be firmly attached to a building, and a cooler or the like can be fixed to this molded product. Also, fix this board underwater,
It can also be used as an underwater heat insulating plate, which is extremely convenient. This complex is made entirely in the factory, and is simply connected with bolts and nuts on site, and is a method of prefabricated construction.

In the mold of the present invention, a portion where a large amount of heat inflow is desired, for example, the inner box of the heat insulation box may be made of a thin material or a material having a high thermal conductivity. In addition, a fin, a heat pipe, or the like may be attached to the portion to promote heat conduction. In the mold of the present invention, a material having poor heat conductivity or a thick material may be used in a portion where the skin is to be thinned.
The material of the metal fitting is preferably a material having good heat conductivity such as brass in order to shorten the molding time. Next, examples of the present invention will be described. [Example 1]

High density polyethylene, density 0.96 g / c
c. A powder having a storage elastic modulus of 1 × 10 ⁴ (Pa) at an angular frequency of 1 (rad / S) at 190 ° C., a low density polyethylene, a density of 0.92 g / cc, a MI of 1.5 and a dichmi peroxide 0.8 PHR , Azodicarbonamide 30P
The material obtained by kneading the HR to form a cube with a side of 3 mm is
The amounts shown in the table were placed in a mold (internal thickness 4 mm) of 200 × 200 × 25 mm in inner method. This mold has a diameter of 5m at the center of the bottom.
A Teflon tube is attached to this, and the tip inside the mold is covered with a small hole in the Teflon sheet, and it is located at the approximate center of the mold. The mixture was heated at 200 ° C. for 25 minutes. The rotation speed was 10 rpm for one and 5 rpm for the other. The obtained molded body had the same shape as that of a mold having a smooth surface, no burrs appeared, the skin and the foam were clearly separated, and the properties were as shown in Table 1, and the heat insulation and moisture absorption resistance were as shown in Table 1. It was excellent in mechanical strength and did not shrink over time. The amount of water absorption was determined by immersing the molded body in warm water at 90 ° C. for 90 days and then measuring the increase in weight. [Example 2]

Rotational molding was performed in the same manner as in Example 1 except that the amount of azodicarbonamide mixed with low-density polyethylene was changed to 20 PHR and the input amount was changed. The obtained results are shown in Table 2, and a molded article excellent in moisture absorption resistance, heat insulation properties and mechanical strength was obtained. [Example 3]

Rotational molding was carried out in the same manner as in Example 1 except that the mixing amount of azodicarbonamide in Example 1 was changed to 10 PHR, and the amount was changed. The obtained results are shown in Table 3, and a molded article excellent in moisture absorption resistance, heat insulation properties and mechanical strength was obtained. [Example 4]

In the same manner as in Example 1, only 200 × 20
An experiment was performed using a mold of 0 × 50 mm and changing the amounts of the skin material and the crosslinked foamable granules. The results are as shown in Table 4, and a molded article excellent in heat insulation, moisture absorption resistance and mechanical strength was obtained. [Comparative Example 1]

Example 1 except that high-density polyethylene, a density of 0.961 and a storage modulus of 4 × 10 ² (Pa) were used.
Experimented in exactly the same way. The results are as shown in Table 5. The molded product obtained had a low storage elastic modulus of the skin material, and thus had an uneven thickness of the skin, a stonewall-shaped skin material, and also had voids, moisture absorption resistance, and heat insulation. It was a molded article with poor properties. [Comparative Example 2]

No. 1 of the first embodiment. In the same manner as in Example 1, the amount of the skin material was set to 49 g, and a molded body having a skin of 0.5 mm was produced. The minimum thickness of the skin of this molded product is 0.2 m
m (t min / t av = 0.4), the skin was too thin, the shape collapsed, the water absorption was 3.3%, and the foamed composite was hygroscopic. [Comparative Example 3]

No. 1 of the first embodiment. In the same manner as in No. 4, a molded body having a skin of 6 mm was produced only by changing the input amount of the skin material to 541 g. The minimum thickness of the skin is 4.0 mm (t min
/Tav=0.67) and a thermal conductivity of 0.11 (Kcal
/ Mh ° C), the insulation was not good because the skin was too thick. [Comparative Example 4]

In the case of No. 1 in the first embodiment, Under the same conditions as in Example 2, the foaming compound was molded with 15.2 g (100% of the foaming agent used). The obtained molded article uses a small amount of a foaming agent and has a low molding pressure, and thus loses its shape, has many voids in the foamed layer, and has a thermal conductivity of 0.123 (Kcal / mh).
° C). [Example 5]

Outer diameter of inner box 500 mm, height 1600 m
m, 6 small holes with a diameter of 10 mm are made in several places of a cylindrical double mold having an inner diameter of 580 mm and a height of 1640 mm, and a Teflon tube is inserted. One end is located at the center of the mold, and the other end is located outside the mold. Put out. Then, a Teflon sheet having a small hole was wound around the tip of the tube near the center. A 20 mm diameter screw hole was made in the center of the bottom of the inner box and the outer box. Next, insert a bolt with a diameter of 20 mm from the bottom of the outer box,
The nut was put apart by mm and the inner box was pierced and fixed with another nut from above the inner box. In this mold, a high-density polyethylene, a density of 0.950 and an angular frequency of 1 (r) at 190 ° C.
ad / S) storage elastic modulus of 4 × 10 ⁴ (PA) 2
0.4 kg, low density polyethylene (density 0.92, MI
3) Dicumyl peroxide (1 PHR), azodicarbonamide (15 PHR) were mixed, and 8 kg of a foamable material (amount of foaming agent used: 267%) formed into a cube having a side of 2 mm was put into a cubic molding machine. Was heated with hot air at 200 ° C. for 30 minutes while the other was rotating at 6 rpm. After cooling, the bolts and nuts are removed, and the foam composite container taken out of the mold has a smooth and beautiful surface, conforms to the shape of the mold, has an integral skin of 3 mm, and has a minimum thickness of 2.2 m.
m, the core foams 11 times and the bubble diameter is 0.5mm
The skin material around the foam particles is not attached, there is no void, the skin and the foam are clearly separated, the two are firmly bonded, the adhesive strength is more than the strength of the foam, the bottom There is a nut, a screw hole with a diameter of 20 mm passes through the bottom, and there is a 2.0 mm thick skin around the nut and the screw hole. This skin is bonded to the skin of the inner box and outer box, and adheres to the foam. Have been
The adhesive strength was higher than the strength of the foam, was excellent in heat insulating properties and strength, and was an insulated container that could be easily connected to metal fittings to allow hot water to be taken in and out for an extremely long time without absorbing the foam. [Example 6]

At the four corners of a 1000 × 1000 × 50 mm square mold, holes having a diameter of 10 mm were formed in the upper and lower plates, and bolts were passed through the lower plate from the upper plate and fixed with nuts. A hole of 7 MM was separately made in this mold, and a tube was inserted into the hole. 5 kg of the powdered high-density polyethylene of Example 1 and 2 kg of the foaming compound of Example 1 (using amount of foaming agent: 246%)
And heated with hot air of 200 ° C. for 30 minutes while rotating biaxially. The foamed composite removed from the mold with the bolts and nuts removed has a uniform thickness of 2 mm with an integral skin, the minimum thickness is 1.5 mm, and the core has a density of 0.035 g / c.
c, a foam having a cell diameter of 0.5 mm, both of which are firmly adhered to each other, have a 10 mm screw hole in each of the four corners, and a 2 mm thick skin around these holes. It was an insulated plate that was joined, adhered to the foam, easily attached to the wall with bolts, had excellent heat insulation, was strong, and did not absorb moisture at all in water for long periods.

[Effects of the Invention] As described above, the foamed composite of the present invention can be manufactured in one step, and does not absorb moisture even when placed in humid air or a low-temperature tank for a long period of time. This is an extremely excellent heat-insulating material for energy saving without lowering. This molded product has excellent mechanical strength such as impact resistance in addition to moisture absorption and heat insulating properties, and is provided with a metal fitting, a small hole, and a molded product having a thick skin around it. This molded product can be taken in and out of warm water, does not absorb moisture even when used in water, has a cooler, etc., and can be firmly fixed to buildings, etc., and has excellent properties. The forming method is extremely useful, and the formed body is an insulating plate,
It is extremely excellent as a heat insulating material such as a heat insulating box and a heat insulating cover.

[Brief description of the drawings]

FIG. 1 is a heat insulating material that does not absorb moisture,

Fig. 2 is a thermal insulation with a stone wall pattern-like skin material phase.

FIG. 3 is a heat insulating material having a void.

[Explanation of symbols]

 1) Skin 2) Foam 3) Stonework-like skin material phase 4) Void

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 9:00 31:10 31:58 (72) Inventor Hiroji Takase 1-13 Wakabacho, Tachikawa-shi, Tokyo -2-306 F term (reference) 4F100 AH02H AH03H AK01A AK03B AK05 AK06 CA01B CA02 DC11 DD31 DE01A DE01B DJ01B DJ05B EJ05B EJ162 EJ422 GB08 HB11A JA15B JD15 JJ02 JK01 JK07A JK10 JLYA02A03A03A03 AG20 AH48 GA03 GB01 GB26 GB29 GC04 GD02 GN01 GN13 GN18

Claims (3)

[Claims] 1. A composite covering the entire surface of a crosslinked polyolefin foam having a density of 0.2 g / cc or less with a plastic skin having a uniform thickness of 1.0 mm or more and a stone wall pattern on the foam layer. A foamed composite characterized in that there is no skin material phase, no voids, and the adhesive strength between the skin and the foam is equal to or higher than the strength of the foam. 2. A composite in which a plastic powder and a crosslinked expandable particulate polyolefin having a size larger than the particles of the powder are placed in a mold and heated while rotating to form a composite in which the entire surface of the foam is covered with a skin. In the manufacturing method, a plastic powder having a storage elastic modulus of 1 × 10 ³ (Pa) or more at an angular frequency of 1 (rad / S) at 190 ° C. is used, and a large amount of foamed A method characterized in that molding is performed at a high molding pressure using an agent. 3. A composite in which the entire surface of a foam is covered with a plastic skin, and there are small holes at right angles to the plate, and a skin having a thickness of 1.0 mm or more is formed around these small holes. A foamed composite, wherein the foamed composite is firmly bonded to at least one of the skins and adheres to the foam around the small holes, and the adhesive strength is not less than the strength of the foam.