JP2001181365A - Method for manufacturing open-cell rigid polyurethane foam for vacuum heat insulating panel-filler material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an open-cell rigid polyurethane foam molded body at a low material cost per unit volume of the molded body, permitting loading a large amount of a filler material and excellent in surface smoothness as well as excellent in loading properties, directional properties of expansion cells and uniformity in the foam density. SOLUTION: A mixture of expandable raw material components comprising a polyol component and an isocyanate component in an equivalent ratio of NCO/OH of about 0.55-0.95 and a blowing agent, preferably water, is cooled down to solidify before expansion and a curing reaction substantially proceed thereby to give a powder of the expandable raw material components, which, if necessary after addition of a filler material, is poured into a space to be molded, raised in its temperature and compressed to effect expansion molding thereby to give a compressed product, which is further subjected to compression molding to give the open cell rigid polyurethane foam molded body having an open cell content of at least 99% with its skin layer remained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an open-celled rigid polyurethane foam molded article. More specifically, the present invention relates to a method for producing an open-celled rigid polyurethane foam having excellent filling properties.

[0002]

2. Description of the Related Art Recently, in order to protect the ozone layer, prevent global warming, etc., for the purpose of preserving the global environment, many manufacturing fields have been pursuing chlorofluorocarbon and energy saving and are required to switch materials. In particular, heat insulating materials such as rigid polyurethane foams have become targets.

[0003] For this reason, various techniques have been proposed in the field of the production of heat insulating materials. For example, a production method using water as a foaming agent is known as a technique for removing CFCs. Further, for the purpose of energy saving, a bag made of a metal-plastic laminate film having gas barrier properties is filled with a core material such as inorganic powder or open-cell body for maintaining a predetermined shape, and the vacuum heat insulating panel structure is sealed under reduced pressure. Etc. have been proposed.

Under these circumstances, rigid polyurethane foams composed of open cells are considered to be lightweight and have high performance, and are used as heat insulating materials for refrigeration and refrigeration equipment for preventing global warming. It is attracting attention as a core material.

[0005] For example, Japanese Patent Publication No. 63-61589,
In Japanese Patent Application Laid-Open No. 6-213561, the Seminar on Thermophysical Properties of Japan ('89 .6.30), etc., a rigid polyurethane foam having open cells made of water foam is used as a core material to reduce the size of foam cells. Further, it has been proposed to obtain a high-performance vacuum heat insulating material by adjusting the shape of bubbles.

[0006] Generally, a rigid polyurethane foam is produced by mixing a polyol component, an isocyanate component and a foaming agent, and forming a foamed raw material component mixture in a space where the mixture is to be molded before the reaction progresses and the fluidity is lost. Is generally performed by foaming. In this case, when these foaming raw material components are mixed, 5 seconds to 2
Minutes, foaming starts, and after 20 seconds to 5 minutes, expansion and resinification are almost completed.

[0007] When the foaming raw material components are mixed in this way, foaming starts soon, and curing proceeds simultaneously with foaming.
It is necessary to quickly fill the void before foaming substantially begins. If you try to inject after foaming starts, the mixture of foaming raw material components quickly loses fluidity, and you have to stop injecting in the middle of injecting, and you can not inject the required amount into the target space. is there. Further, even if injection is possible, if the fluidity is low, problems may occur such that it is not possible to reliably fill every corner of the void. Furthermore, even if the injection can be performed before foaming starts, depending on the size and shape of the space to be injected, the surface tension of the mixture of the foaming raw material components, the foam hardening time, and the like, the injection cannot be reliably performed over the entire space. Sometimes.

[0008] The core material for a vacuum insulation panel is required to have extremely high filling properties and physical properties. However, the rigid polyurethane foam obtained by the conventional production method has a problem that poor filling or accompanying deterioration in physical properties occurs. .

Most of the open-celled rigid polyurethane foam used as a core material in the above-mentioned conventional vacuum insulation panel is manufactured by a so-called rigid slab foam, a double conveyor system for forming a continuous panel, or a compression molding.

However, in the rigid polyurethane foam obtained by these production methods, open cells are not formed in the surface layer called the skin layer of the obtained molded article. The fact is that we have a form. Moreover,
The skin layer removed in this way is 50% of the total volume
Furthermore, the generated waste not only goes against the preservation of the global environment, but also causes a decrease in productivity and an increase in material cost per unit volume of the molded body. Furthermore, the obtained open-celled rigid polyurethane foam is limited in shape and lacks surface smoothness, and cannot be said to have sufficient strength depending on the use.

[0011] Further, as a baking treatment for removing gas generated from the open-celled rigid polyurethane foam, a treatment using a hot-air circulating furnace is generally performed, but even after such treatment is performed, Furthermore, since gas is generated in the long term, the use of a getter agent for adsorbing the gas is indispensable when the open-celled rigid polyurethane foam is used for a heat insulating material, particularly for a vacuum heat insulating material,
This also causes a drop in productivity and a significant rise in product costs, and is an obstacle to the spread of these products.

Of course, even in the conventional open-celled rigid polyurethane foam, water is used as a foaming agent for the purpose of de-fluorocarbonization during production, but the strength is reduced at the time of foam molding and the flyability (brittleness of the foam) is reduced. At present, high quality molded articles have not been obtained.

[0013]

Accordingly, the present invention solves the above-mentioned problems and can be used without removing the skin layer, the material cost per unit volume of the molded article is low, and the surface smoothness is further improved. It is an object of the present invention to provide a method for producing an open-celled rigid polyurethane foam molded article having excellent filling properties.

[0014]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the foaming raw material components have been mixed, and the foaming and curing reaction has not substantially progressed. After cooling and solidifying the component mixture, by foaming the foamed raw material component mixture powder obtained by pulverization,
A process in which a rigid polyurethane foam having excellent filling properties can be obtained by uniformly injecting into a mold, and furthermore, a blending ratio of a polyol component and an isocyanate component in a foaming raw material component mixture is adjusted to a specific range to perform foam molding. Among them, it was found that by foaming the foam, it was possible to obtain an open-celled rigid polyurethane foam molded article having extremely high communication throughout the molded article even when the skin layer was left. Completed the invention.

That is, the present invention is as follows. (1) An open-cell rigid polyurethane foam molded article having a degree of communication of 99% or more with a skin layer remaining by foaming a foaming raw material component mixture containing a polyol component, an isocyanate component, and a foaming agent. In the production method, the content ratio of the polyol component and the isocyanate component in the foaming raw material component mixture is about 0.55 to 0.95 in equivalent ratio of NCO / OH, and the following step (A)
Method for producing open-celled rigid polyurethane foam molded article containing (F): (A) The foaming raw material component mixture in which foaming and curing reactions have not substantially progressed is cooled and solidified, and then pulverized to form a foaming raw material component. A step of obtaining a mixture powder, (B) a step of injecting the foamed raw material component mixture powder into a space to be molded,
(C) a step of raising the temperature of the foaming raw material component mixture to a foaming reaction temperature or higher, (D) a step of free-foaming the foaming raw material component mixture, and (E) a free-foaming product obtained in the free foaming step of the step (D). A first compression step of compressing before the gel time, and (F) a second compression step of further compressing the compressed material obtained in the step (E) before the rise time. (2) The production method according to (1), wherein the compression in the first compression step of the step (E) is performed by restricting expansion of the free foam. (3) The method according to (1) or (2), wherein the second compression in the step (F) is performed immediately after degassing. (4) The compression in the first compression step of (E) is (D)
Before the gel time of the free-foaming process in the free-foaming step of the step, the free-foaming is carried out by compressing to 40 to 80% of the volume of the free-foaming without compression in the step (D);
The compression in the second compression step is 10 to 30% of the volume of the compressed product obtained in the step (E) immediately before its rise time, and is further expanded without compression in the step (D). (1) The method according to any one of (1) to (3), wherein the method is performed by compressing. (5) The step (G) of dispersing a filler in the foamed raw material component mixture powder obtained in the step (A) is performed before the step (B), in any of (1) to (4). The production method according to one of the above. (6) The production method according to any one of (1) to (5), wherein the blowing agent is water.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (1) Open-cell rigid polyurethane foam of the present invention The open-cell rigid polyurethane foam of the present invention is a rigid polyurethane foam obtained by foam-forming a foaming material containing a polyol component, an isocyanate component and a foaming agent. The molded article has a communication degree of 99% or more with the skin layer remaining.

Here, the “skin layer” of the foam molded article used in the present specification refers to a surface layer portion / surface layer in the foam molded article. As described above, in the conventional rigid polyurethane foam molded article, since the skin layer was not sufficiently open-celled, a foamed rigid polyurethane foam was obtained after foam molding in order to obtain an open-celled rigid polyurethane foam molded article. An operation for removing the skin layer from the foamed molded article was required. The open-celled rigid polyurethane foam molded article of the present invention is characterized by comprising a rigid polyurethane foamed molded article having a degree of communication of 99% or more while leaving a skin layer.

The term "communication degree" as used herein means an open cell ratio, and specifically, ASTM-D19
When the closed cell rate measured based on 40 is defined as Cr, it can be calculated by the formula of 100-Cr.

As described above, the open-celled rigid polyurethane foam molded article obtained by the production method of the present invention has a communication degree of 99% over the entire molded article with the skin layer remaining.
As described above, it has a sufficient degree of communication to be used as a core material or the like of the vacuum heat insulating material.

The density of the open-celled rigid polyurethane foam molded article obtained by the production method of the present invention is appropriately selected according to the use in which the molded article is used, and is not particularly limited. For example, when the molded body is used as a core material of a vacuum heat insulating material,
Specifically, a density in the range of about 90 to 180 kg / m ³ is preferably mentioned, and more preferably 90 to 150 k / m ^3.
g / m ³ , particularly preferably 12 g / m ^3.
Densities in the range of about 0 to 150 kg / m ³ are mentioned.
The density distribution of the open-celled rigid polyurethane foam molded article obtained by the production method of the present invention is not particularly limited as well as the density of the entire molded article, but 0.5 mm from the surface of the molded article toward the inside. It is preferable that the density of the surface layer portion constituting the portion up to and near the density of the center portion excluding the surface layer portion of the molded article is made specific. Specifically, the density of the surface layer portion is set to about 0. The density is preferably 9 to 1.5 times, and more preferably the density of the surface layer is about 1.0 to 1.3 times the density of the central part. Also,
Even in the open-celled rigid polyurethane foam molded article of the present invention in which the density of the surface layer portion is close to the density of the central portion, the degree of communication over the entire molded body is 99% or more. Both are 99% or more. In the manufacturing method of the present invention, in order to set the density ratio between the surface layer portion and the central portion to be in the above range, adjustment of the raw material components and adjustment of the mold temperature may be mainly performed.

Hereinafter, unless otherwise specified, the “surface layer portion” refers to a surface layer portion that constitutes a portion extending from the surface of the molded body to 0.5 mm from the surface to the inside, and the “center portion”
It is the center of the molded body excluding the surface layer. (2) Method for producing open-celled rigid polyurethane foam molded article of the present invention The open-celled rigid polyurethane foam molded article of the present invention can be obtained by mixing and foaming a foaming agent, a polyol component and an isocyanate component. As a specific production method, the content ratio of the polyol component and the isocyanate component in the foaming raw material component mixture is NCO /
A mixture containing the polyol component, the isocyanate component, and the foaming agent having an equivalent ratio of OH of about 0.55 to 0.95 as a foaming raw material component mixture is foamed by a process including the following processes (A) to (F). Molding means may be used. (A) a step of cooling and solidifying the foaming raw material component mixture in which the foaming and curing reaction has not substantially progressed, and then pulverizing to obtain a foaming raw material component mixture powder; (B) the foaming raw material component mixture powder Injecting into the space to be molded,
(C) a step of raising the temperature of the foaming raw material component mixture to a foaming reaction temperature or higher, (D) a step of free-foaming the foaming raw material component mixture, and (E) a free-foaming product obtained in the free foaming step of the step (D). Compress before gel time.
Compression step), (F) the above (E)
A second compression step of further compressing the compressed material obtained in the step before the rise time (hereinafter, also referred to as “second compression”).

In the production method of the present invention, the content ratio of the polyol component to the isocyanate component in the foaming raw material is adjusted to NC.
By setting the equivalent ratio of O / OH to about 0.55 to 0.95, the raw material components containing these are mixed and foamed only, that is, without removing the skin layer after foaming as in the conventional method. That is, the open-celled rigid polyurethane foam molded article of the present invention having a degree of communication of 99% or more over the entire molded article with the skin layer left is obtained. This is because by setting the equivalent ratio of NCO / OH within the above range, the balance of the elongation-strength of the skeletal resin forming the bubbles is lost, and the bubbles from the inside of the foamed molded article to the skin layer are sufficiently dispersed. This is because bubbles can be broken.

The content ratio of the polyol component and the isocyanate component in the foaming raw material of the conventional general open-celled rigid polyurethane foam is determined in consideration of the compressive strength of the open-celled rigid polyurethane foam obtained by removing the skin layer. The equivalent ratio of NCO / OH is 1 to 1.2. For example, as described in JP-A-6-213561, the free foam density is 20 kg / m2 using water as a foaming agent.
^When producing the foam of ( ³ ), the polyol component (A)
The isocyanate component (B) has a B / A (weight ratio) of 1.5 to 2.0 and uses a large amount of the isocyanate component, so that the curing property is poor, the flyability increases as a whole, and the durability is insufficient. And a good molded product could not be obtained.

However, in the present invention, as described above, the equivalent ratio of NCO / OH in the raw material is set to about 0.5
By reducing the flyability to 5 to 0.95, the problem of the flyability can be cleared, and bubbles are sufficiently broken from the inner part of the foamed molded article to the skin layer part, and the skin layer is left as it is. In this state, it is possible to obtain an open-celled rigid polyurethane foam molded article in which the degree of communication is 99% or more over the entire molded body, specifically, the degree of communication between the surface layer portion and the central portion is 99% or more.

When the equivalent ratio of NCO / OH is less than 0.55, the strength is extremely reduced and the molded product is liable to shrink, and when it exceeds 0.95, the cells become coarse and open cells extend to the skin layer. It becomes difficult to convert.

Also, unlike the conventional manufacturing method, such a manufacturing method of the present invention does not require the removal of the skin layer in order to secure the degree of communication, so that the surface is smooth and various shapes are possible. It is an environmentally friendly system that can respond and does not generate any waste in the manufacturing process, and can fully respond to future recycling.

As the polyol component used in the production method of the present invention, any polyol component which is generally used as a foaming raw material component of a polyurethane foam can be used without any particular limitation. Polyether polyols such as tetramethylene glycol and modified products thereof such as, for example, tolylenediamine-based polyethers, sucrose-based polyethers, and ethylenediamine-based polyethers; condensed polyester polyols, lactone-based polyester polyols, and polycarbonate polyols; Polyester polyols; polybutadiene polyols; acrylic polyols; partially saponified ethylene-vinyl acetate copolymers;

As the isocyanate component used in the present invention, any isocyanate component which is usually used as a foaming raw material component of a polyurethane foam can be used without any particular limitation. Specifically, polymeric 4,4 ' Examples include diphenylmethane diisocyanate (polymeric MDI), carbodiimide-modified MDI, and tolylene diisocyanate.

Most of such polyol components or isocyanate components usually used as foaming raw material components for polyurethane foams are commercially available, and can be used in the present invention.

As the foaming agent used in the present invention, HFC,
HCFC, cyclopentane, water and the like can be mentioned, and one or more of them can be appropriately selected. However, considering environmental aspects, ODP (ozone depletion coefficient) is considered.
= 0, GWP (global warming potential) ≒ 0, and it is preferable in the present invention to use highly safe water without explosion or fire.

The foaming raw material of the open-celled rigid polyurethane foam used in the production method of the present invention includes, in addition to the above components, a catalyst, a chain extender, a crosslinking agent, a foam stabilizer, a communicating agent, a filler, a plasticizer, Various additives used in the production of ordinary polyurethane foams, such as a flame retardant, can be appropriately added.

Of these additives, the filler is preferably added after the above step (A) and before the step (B). That is, the step (G) of uniformly dispersing the filler in the foamed raw material component mixture powder obtained in the step (A) is performed. Normally, it is difficult to disperse a solid filler, and it is particularly difficult to add a large amount of a filler. However, in the present invention, the filler is dispersed by adding the filler to the powder of the foamed raw material component mixture. The properties are improved, and an open-cell polyurethane foam having uniform physical properties can be obtained.

Examples of the filler added in the step (G) include metals such as aluminum, iron and lead, and inorganic fillers such as mica, glass, quartz, silica, alumina, talc and graphite. Mica is preferred from the viewpoint of improving the heat insulating property because it prevents radiation heat. As the shape of the filler, powder, fibrous, flake, foil and the like can be mentioned, but from the viewpoint of improving heat insulation, flake and foil are preferable because they prevent radiation heat from the outside. . Although the amount of the filler used depends on the type of the filler, it is 10 parts by mass relative to 100 parts by mass of the polyurethane foam.
It is preferably from 50 to 50 parts by mass, more preferably from 15 to 30 parts by mass.

The other additives are preferably added from the beginning as a foaming raw material component. Examples of the catalyst include organometallic catalysts and amine catalysts such as tertiary amines and amine salts. Specific examples of the chain extender and the crosslinking agent include glycols, and specific examples of the foam stabilizer include various surfactants, preferably silicone surfactants. Further, barium stearate and the like are preferably mentioned as the communicating agent.

The foaming raw material component of the open-celled rigid polyurethane foam molded article of the present invention contains such a polyol component, an isocyanate component, a foaming agent and other various components. The content ratio of the isocyanate component is in the range of about 0.55 to 0.95 in terms of the equivalent ratio of NCO / OH, and is preferably about 0.60 to 0.80.

As the amount of the blowing agent used in the production method of the present invention, the amount of the blowing agent usually used in producing a polyurethane foam can be applied as it is. For example, when water is used as the foaming agent, the blending amount may be about 4 to 8% by mass based on the blending amount of the polyol component in the foaming raw material. Further, as for the other raw material components appropriately blended with the foaming raw material, the amount of the raw material components used in producing a polyurethane foam can be applied as it is.

In the production method of the present invention, a foaming raw material component mixture is prepared by the same method as that used for producing a polyurethane foam, for example, by mixing the raw material components with a high-pressure foaming machine, for example. Method.

In general, the curing reaction of the foamed raw material component mixture already proceeds gradually at room temperature, depending on the type of each of the above-mentioned raw material components. The time until a substantial reaction occurs varies considerably depending on the type of foaming raw material component, ambient temperature, etc.
Although it cannot be said unconditionally, it is about 10 to 60 seconds. In the production method of the present invention, the foaming raw material component mixture is rapidly cooled to a temperature below its freezing point before the foaming and curing reaction of the foaming raw material component mixture substantially proceeds, and the foaming and curing reaction is performed. And the step (A) of solidifying the foamed raw material component mixture. For this reason, it is preferable to cool the foaming raw material component mixture within 5 seconds after the preparation of the foaming raw material component mixture.

In the present invention, the method of cooling and solidifying the foaming raw material component mixture as the above-mentioned step (A) is not particularly limited, and may be any method commonly used. For example, in a mixing vessel equipped with a cooling jacket, a method of stirring and mixing and cooling the foaming raw material component, or directly mixing an inert and volatile cryogen such as liquid nitrogen or dry ice with the foaming raw material component mixture. Methods and the like can be used.
At this time, if the components used in the foaming raw material are cooled in advance so as not to solidify, the energy and time required for cooling after mixing can be reduced, and the time until the foaming and curing reaction starts can be extended. Advantageously, it can be forced.

When an inert volatile cryogen such as liquid nitrogen or dry ice is directly mixed with the foaming raw material component mixture, the amount of the cryogen is not particularly limited as long as it can be cooled and solidified. The amount is preferably 50 to 200 parts by mass, more preferably approximately the same.

The cooling temperature varies depending on the type and amount of the foaming raw material component used, and cannot be specified unconditionally, but may be at least the temperature at which the foaming raw material component mixture is completely solidified in a frozen state and can be pulverized. . Specifically, -30
C. or lower, and more preferably cooled to -50 C. or lower. Further, the time required for cooling to such a temperature is preferably as short as possible, and specifically,
Preferably, the cooling is completed within about one minute. Thereby, the foaming and curing reaction of the foaming raw material component mixture in the present invention can be substantially suppressed.

The foamed raw material component mixture thus cooled and solidified is then pulverized to obtain a foamed raw material component mixture powder. The pulverizing method in the above-mentioned step (A) is not particularly limited, and a usual method can be used. For example, a mechanical pulverizing method using a kneader, a cutter, a ball mill, or the like can be used. Further, a method of pulverizing the obtained solidified product with a stirrer such as a homomixer may also be used. When pulverizing with a stirrer, the number of revolutions for pulverizing is not particularly limited, but is preferably 6,000 to 8,000 rpm, more preferably 7000 to 7,500 rpm. The stirring time is not particularly limited as long as the foaming raw material component mixture is completely powdered, but specifically, about 5 to 10 seconds at the above-mentioned rotation speed is preferable. When performing the step (G) of dispersing the filler, the foaming raw material component mixture is pulverized by the stirrer, and then the filler is added to the obtained foaming raw material component mixture powder and dispersed by the stirrer. Is also good.

The size of the foamed raw material component mixture powder can be varied widely according to the size and shape of the space to be filled, the properties required for the final molded body, and the like. Next, a step (B) of filling the powder into the space to be molded is performed. In the present invention, as the “vacant space”, a mold similar to that used for foam molding of a usual polyurethane foam is used, but it is a mold having a structure that can be compressed in the subsequent steps (E) and (F). Preferably, specifically,
For example, a mold including an upper mold and a lower mold, a resin mold and the like can be mentioned.

Further, in the present invention, by using the foaming raw material component mixture as a powder, an extremely narrow space which cannot be sufficiently spread to every corner by the conventional injection foaming method can be obtained. It is possible to uniformly inject into places and complicated parts. The injection method is not particularly limited, and examples thereof include a method of uniformly spraying with a metal spatula or the like, and a method of uniformly spraying by using bi-blade vibration.

After filling, a step (C) of raising the temperature of the empty space to a temperature equal to or higher than the foaming reaction temperature of the foaming raw material component mixture is performed. This temperature rise depends on the type of the foaming raw material component used, but when the foaming reaction temperature of the foaming raw material component mixture is room temperature, it can be performed by leaving the mixture at room temperature.
Alternatively, the heating may be performed by external heating. In the present invention, the temperature rise is preferably 30 to 80 ° C,
More preferably, it is 40 to 60 ° C.

After the temperature is raised, the following foam molding is performed. The foam molding method in the production method of the present invention is compression molding, and specifically, is a method including the above-described steps (D) to (F).

That is, the step (D) is a step of free-foaming the foamed raw material mixture, and the step (E) is a first step of compressing the free-foamed product in the free-foaming step of the step (D) before the gel time. The step (F) is a second compression step of further compressing the compressed product obtained in the step (D) before the rise time.

The “volume in the case of free foaming without compression in the step (D)” described here means, for example, that when the foamed raw material component mixture is put into a container having an open top and then freely foamed, It means the volume of the foam obtained by free-foaming the foaming raw material component mixture while leaving it open, that is, without restraining the upper surface, and then curing.

As the degree of compression in the compression step (E), specifically, the volume of the obtained compressed product is 40 to 80% of the volume in the case of free foaming without compression in the step (D). Degree, more preferably about 40 to 60%.

The first compression in the step (E) is as follows:
40-80 of the volume when free foaming without compression in the process
%. For example, before gel time,
A method of compressing the free-foamed material expanded by foaming by pressing the free-foamed product to about 40 to 80% of the volume when the free-foamed product is free-foamed without being compressed in the step (D), or at a predetermined position. A method in which a mold or the like is fixed, and the free foam is restrained from expanding due to foaming and is restrained to be about 40 to 80% of the volume when the free foam is free foamed without compression in the step (D). No. In the present invention, the first
The compression in the compression step is preferably performed by restraining the expansion of the free foam.

As the degree of compression in the compression step (F), the volume of the resulting compressed product, that is, the volume of the open-celled rigid polyurethane foam molded article of the present invention is as follows:
Specifically, the degree of compression is preferably about 10 to 30% of the volume of the case where free foaming is performed without compression in the step (D). More preferably, the degree is about 20 to 30%. The second compression in the step (F) is preferably performed before the rise time, and is particularly preferably performed immediately after gas release.

In the open-celled rigid polyurethane foam molded article of the present invention obtained by producing in this manner, the cells have a shape in which the cells are crushed from the inner part of the molded article to the skin layer part, and the resin structure is For example, it is a “fiber laminated shape” in which nonwoven fabrics are laminated.

The first compression in the step (E) and the second compression in the step (F) can be completely performed by one compression operation, respectively, or can be divided into several compression operations. It is also possible to do. Further, it is preferable that the second compression is performed in the same direction as the first compression in that the bubbles are easily formed into a “fiber-laminated shape”.

In the second compression step, the gelation proceeds, the resin strength also develops, and the density is made uniform from the surface layer to the inside by the first compression. Since this is performed, bubbles can be completely broken down to the skin layer by the crushing effect at this time, and communication can be achieved. That is, by performing compression molding in multiple stages at the above timing, it is possible to obtain a molded product having a communication degree of 99% or more including the skin layer.

The terms "gel time", "outgassing" and "rise time" used herein are defined as follows. That is, the time to start drawing a thread when piercing and pulling up a glass rod or the like in foaming during foaming is `` gel time '', the phenomenon that gas is discharged from the foaming foam surface is `` outgassing '', the time when foaming ends, In other words, the time when the expansion of the form stops is called “rise time”.

The molding method including the above steps (D) to (F) will be described with reference to FIGS.
A more specific description will be given in comparison with the production process diagrams of the free foam shown in (1) and (2).

FIGS. 2 (1) and 2 (2) are views showing the above step (D). FIG. 2 (1) shows the above-mentioned process in a space formed by the upper mold 2 and the lower mold 3. 2 (2) shows a state in which the foaming raw material component mixture powder 4 uniformly injected in (1) is free-foamed, and the upper mold 2 The state in which the free foam 5 is formed in the space formed by the lower mold 3 is shown. FIG.
(1) The upper mold 2 represents a state in which the first compression is fixed at a predetermined position in advance in the step (E) because the first compression is performed by restraining the expansion of the free foam. Here, the material and shape of the mold used are appropriately selected. At this time, the mold and the ambient temperature are adjusted to appropriate temperatures by normal temperature or heating.

In comparison with this, FIG. 4 showing the manufacturing process of the free foam is shown in FIG.
Only the foaming raw material component mixture powder 4 similar to the above is injected into the lower mold 3 in the same amount as in the case of FIG. FIG. 4 (2) shows a state in which the foamed raw material component mixture powder injected in FIG. 4 (1) is freely foamed up to the rise time without any restraint, and is further cured in the lower mold 3 as it is. And X indicates the foam obtained thereby.

FIG. 2 (3) is a view showing the above step (E), in which the upper mold 2 is fixed at a predetermined position before the free foam expands by foaming. This shows a state in which the expansion is restrained (first compression) and the compressed material 6 is obtained. The expansion of the free foam is restrained by fixing the upper mold 2 at a predetermined position, and the volume of the obtained compressed material 6 is expanded without being compressed as shown in FIG. It is preferably performed so as to be 40 to 80% of the volume of the foam X. The time when the expansion of the free foam is restricted by the upper mold or the like is before the gel time of the free foam obtained in the step (D). Preferably about 5 to 10 seconds before the gel time. Since the gel time and the volume of the obtained natural foam vary depending on the type of foaming material, mold temperature, and the like, it may be measured in advance by performing a preliminary test under the same conditions as the production conditions.

FIG. 2 (4) is a view showing the above step (F), in which the upper die 2 is further pushed by the press 1 to compress the compressed material 6 (second compression), and the open-cell rigidity is reduced. The state where polyurethane foam 7 was obtained is shown. In the second compression in the step (F), the volume of the obtained compressed product is as shown in FIG.
It is preferable that the foaming is performed so as to be 10 to 30% of the volume of the foam X which is free-foamed without being compressed as shown in (2). The time at which the second compression is performed by the press 1 is not particularly limited as long as it is before the rise time, but a preferable time is immediately after degassing. The outgassing time and rise time are also similar to the gel time above.
It may be measured in advance by a preliminary test or the like.

The first compression in the above-mentioned step (E) is 40 times the volume of the free-foamed product expanded by foaming before the gel time when the free-foamed product is free-foamed without being compressed in the step (A).
FIG. 3 shows the foam molding in the case where the compression molding is performed by, for example, pushing in so as to be about 80%, and specifically, it is as follows.

FIGS. 3 (1) and 3 (2) are views showing the above step (D), and FIG. 3 (1) shows the inside of the cavity formed by the upper mold 2 and the lower mold 3 of the mold. FIG. 3 (2) shows a state where the foamed raw material component mixture powder 4 obtained by sufficiently mixing the respective raw material components described above is uniformly injected.
The foamed raw material component mixture powder uniformly injected in step (1) is free-foamed, and the free-foamed material (5) is placed in the space formed by the upper mold (2) and the lower mold (3).
Respectively show the state filled. Here, the material and shape of the mold used are appropriately selected. Further, the mold may be heated as needed.

FIG. 3 (3) is a view showing the above-mentioned step (E), wherein the expanded free-foamed product is preferably 40 to 80% of the volume when the expanded free-foamed product is free-foamed without being compressed in the step (A). The upper mold 2 is gradually pushed in by the press 1 so as to reach a degree, and the free foam 5 is compressed (first compression) to obtain a compressed product 6. In the first compression, similarly to the constraint in FIG. 2, the volume of the obtained compressed material 6 is 40 to 80% of the volume of the foam X which is freely expanded without compression as shown in FIG.
It is preferable to be performed so that The first compression using the press 1 is performed before the gel time of the free foam obtained in the step (D). The timing of performing the first compression is not particularly limited as long as it is before the gel time of the free foam, but as a preferable timing,
About 5 to 10 seconds before the gel time. Since the degassing time and the volume of the obtained natural foam vary depending on the type of the foaming material, the mold temperature, and the like, it may be measured in advance by performing a preliminary test under the same conditions as the manufacturing conditions. FIG. 3D is similar to FIG. 2D.

FIG. 5 is a view showing an example of an open-celled rigid polyurethane foam molded article obtained by the production method of the present invention. FIG. 5 (a) is an external perspective view, and FIG. 5 (b) is a cross-sectional view. . In the open-celled rigid polyurethane foam molded article 7 shown in FIG. 5, the density of the surface layer is about 0.9% of the density of the central part.
It is an open-celled rigid polyurethane foam molded article of the present invention having a ratio of up to 1.5 times. The surface layer portion 7a and the central portion 7b constituting a portion extending from the surface to 0.5 mm from the surface of the open-celled rigid polyurethane foam molded article 7 shown in FIG. Surface layer 7a
Is about 0.9 to 1.5 times the density of the central portion 7b.

The production method of the present invention preferably further comprises a step of subjecting the foam molded article obtained by the foam molding to a baking treatment by irradiation with far infrared rays. In the baking treatment by irradiation with far-infrared rays, it is possible to perform baking with far-infrared rays at substantially the same temperature from the central portion to the surface layer portion of the foamed molded product. It is possible to obtain a molded body having high strength. This is because the wavelength range of 5 to 20 μm of the far infrared rays coincides with the characteristic absorption of the polyurethane resin, so that resonance vibration is generated by the mutual wavelength action, and the inner layer generates heat from the center of the molded body. It works stably and directly to the part to promote the escape of adsorbed gas such as water and air more quickly, and the after-curing effect often seen in so-called thermosetting resins works more greatly than conventional hot-air drying ovens. This is presumed to be the result of increasing the strength of the resin constituting the cell skeleton.

The open-celled rigid polyurethane foam molded article obtained by the production method of the present invention can be used, for example, as a heat insulating material. Specifically, in the wall of the device that requires heat insulation properties, for example, an outer box of a refrigerator or the like,
It can be used by being directly housed in a wall formed by an inner box.

The open-celled rigid polyurethane foam molded article obtained by the production method of the present invention has excellent strength and a smooth surface. Therefore, a heat insulating material using the same has excellent strength and its surface is smooth, so that its appearance is improved. For example, it is possible to improve the quality. In addition, since the filler can be uniformly dispersed, it is possible to provide a filler having an excellent heat insulating property.

As a method of producing the vacuum heat insulating material of the present invention, the open-celled rigid polyurethane foam molded article obtained by the above-mentioned production method is inserted into a container made of a gas barrier film so as to cover the entire molded article. After depressurizing the inside, it is sealed to form a vacuum heat insulating material.

The shape of the container used in the method for producing the vacuum heat insulating material is not particularly limited, but a bag shape is preferable in consideration of the resistance of the gas barrier film having various structures during vacuum forming. Further, as conditions for reducing the pressure inside the container, 133 × 10 ^{−1 to} 133 × 10 ⁻³ Pa (1 × 10
^{About -1} to 1 × 10 ⁻³ torr).
Here, "depressurizing the inside of the container" means, specifically, all of the void portion inside the open-celled rigid polyurethane foam molded article inserted into the container and the void portion between the container and the molded article are This refers to performing a decompression treatment such that the pressure is reduced.

The gas barrier film constituting the container used in the present invention includes, without particular limitation, those similar to the gas barrier films usually used for vacuum heat insulating materials. A plastic laminated film may be used. More specifically, a laminate film having a three-layer structure of a polyethylene terephthalate film / aluminum foil / a high-density polyethylene film is exemplified. When such a three-layer laminated film is used in the present invention, the inside of the container is configured to be a high-density polyethylene film.

Some of such films use a stainless steel foil as an alternative to the aluminum foil. However, since these films have a low thermal conductivity, they are also effective in avoiding heat bridges. If the production technology is established, higher performance heat insulation can be expected. Further, an acrylonitrile film, a vinyl acetate copolymer film, or the like can be used instead of the polyethylene terephthalate film or the high-density polyethylene film.

In the method of manufacturing the vacuum heat insulating material, the container is sealed after decompression by, for example, heat sealing the gas barrier film. Is preferably composed of a high-density polyethylene film. This is because the high-density polyethylene film is more excellent in the heat-sealing property than the acrylonitrile film or the like, so that the reliability of the gas barrier after sealing is high.

The vacuum heat insulating material using the open-celled rigid polyurethane foam molded article obtained by the above production method is obtained by removing the skin layer from the open-celled rigid polyurethane foam molded article used as the core material. Since the material surface is smooth, the appearance of the obtained product is improved. Further, if a mold used for producing the core material is subjected to processing such as a grain pattern, the design of the product can be improved without post-processing. Furthermore, by using the open-celled rigid polyurethane foam molded article of the present invention that has been subjected to baking treatment by irradiation with far-infrared rays as required, it is possible to achieve high quality, such as excellent strength, in the field of refrigeration equipment only. Instead, it can be widely applied to, for example, freezers, storage containers, pipe covers, and houses.

In the open-celled rigid polyurethane foam molded article of the present invention, the NCO / OH equivalent ratio of the foaming raw material component mixture used for the production is about 0.55 to 0.55.
Since it is 0.95, the heat deformation temperature is low, and since the resin structure has a fiber-laminated shape, the bending Young's modulus is small, and it has good follow-up to deformation. After the used plate-shaped vacuum heat insulating material is heat-treated at 80 to 150 ° C. for several minutes, it can be formed into a vacuum heat insulator having various shapes such as a cylindrical shape having a curvature.

Further, after the above-described open-celled rigid polyurethane foam molded article immediately after foam molding is subjected to baking treatment by irradiation with far-infrared rays, the molded article is entirely covered in a container made of a gas barrier film. The vacuum insulating material obtained by inserting the container, depressurizing the inside of the container, and sealing to form a vacuum insulating material is a conventional open-cell rigid polyurethane foam molded product because the molded product does not generate gas for a long time. A getter agent, which is a gas adsorbent required in a vacuum heat insulating material having a core material of, is unnecessary.
Of course, weak baking conditions (such as using a hot air dryer)
When using an open-celled rigid polyurethane foam molded article performed in the above, or an adsorbed gas generated from the molded article,
It is also possible to use a getter agent for the purpose of further increasing the safety against gas entering from the outside. In addition, in such a method for manufacturing a vacuum heat insulating material, the manufacturing process can be made a continuous continuous process, which is preferable in terms of production efficiency.

[0076]

Embodiments of the present invention will be described below.

[0077]

Example 1 and Example 2 According to the production steps shown in FIGS. 1 and 2, an open-celled rigid polyurethane foam molded article of this example was produced. <Cooling and solidification of the foaming raw material>
100 parts by mass of a mixture of 300 mg KOH / g tolylenediamine-based polyether, 450 mg KOH / g sucrose-based polyether, and 500 mg KOH / g ethylenediamine-based polyether in a ratio of 5: 3: 2 as a polyol component was foamed. 6 parts by mass of water, 1.0 part by mass of a foam stabilizer (trade name "SZ-1919" manufactured by Nippon Unicar), and 0.5 parts by mass of Kao Riser No. 31 manufactured by Kao as a catalyst. Parts, 4 parts by mass of barium stearate as a communicating agent, and a trade name “C-MDI 44V-” manufactured by Sumitomo Bayer Ltd. as an isocyanate component.
20 "is mixed at a ratio of 132 parts by mass (NCO / OH equivalent ratio 0.7) using the high-pressure foaming machine shown in FIG. 1 (1). The discharge rate of the high-pressure foaming machine is 1 kg / min. Using a high-pressure foaming machine, 100 g of a foaming raw material (discharge time: 6.0 seconds) was discharged into a heat insulating container.

At this time, the heat insulating container has been cooled to -15 ° C. As shown in FIG. 1 (2), 100 g of liquid nitrogen (LN ₂ ) was added from the LN ₂ supply valve one second after discharging the foaming raw material component mixture. Next, as shown in FIG. 1 (3), the mixture was stirred using a homomixer 3 seconds after the addition of LN ₂ . The stirring speed was 7000 rpm, and the stirring time was 7 seconds. After the foaming raw material was completely pulverized, the obtained foaming raw material component mixture powder 18 was quickly (after stirring for 2 seconds) sprayed onto the lower mold 3 (200 × 200 mm) of the mold. At this time, the substantial amount of the foamed raw material component mixture powder 18 sprayed was 85 g.

In Example 2, 20 g of flaky mica (average diameter: 1 mm) was dispersed in the powder of the foam raw material mixture of Example 1. The actual amount sprayed on the mold was 105 g.

The mold and the atmosphere temperature were kept at 50 ° C. in advance, and the foamed raw material component mixture powder 18 was evenly sprayed on the aluminum mold. <Foam Molding of Foaming Raw Material> First, as shown in FIG. 4, with the upper mold 2 (not shown in the figure) of the metal mold fully pulled up, the embodiment obtained above in the lower mold 3. The foamed raw material component mixture powder 4 of Example 1 and Example 2 was sprayed and freely foamed, and the gel time, outgassing time, and rise time were measured and completely cured to obtain a hard polyurethane free foam X. (See FIG. 4 (2)). In addition,
The density of the obtained free foam X was 40 kg / m ³ when the foaming raw material of Example 1 was used. The weight was 60 kg / m ³ when the foaming raw material of Example 2 was used.

FIG. 2A shows a state in which the foamed raw material component mixture powder 4 has been sprayed into the space formed by the upper mold 2 and the lower mold 3 of the mold. At this time, as shown in FIG. 4 (2), the upper mold 2 is fixed so that its volume is 60% of the volume of the foam X that has been freely foamed without being compressed.

In FIG. 2 (2), the foaming raw material component mixture powder 4 injected in FIG. 2 (1) was freely foamed in a space formed by the upper mold 2 and the lower mold 3 before the gel time. 4 shows a free foam 5. When the free foam 5 is freely foamed, it comes into contact with the upper mold 2, but when the foaming is further continued, the free foam 5 is suppressed from foaming as shown in FIG. 2 (3) (step (B)), and the foam X Of compressed material 6 which is 60% of the volume of The time when the free foam 5 contacts the upper mold 2, that is, the time when the free foam 5 is restrained by the upper mold 2, is set to be 5 to 10 seconds before the gel time. Immediately after degassing, as shown in FIG. 2 (4), the upper die 2 is further pressed by the press 1 to compress the compressed material 6 ((C) step), and the volume is shown in FIG. 4 (2). An open-celled rigid polyurethane foam 7 having a volume of 25% of the volume of the foam X which was freely foamed without being compressed was obtained. At the stage of FIG. 2A and FIG. 2B, the mold temperature and the ambient temperature were adjusted to 50 ° C.

FIG. 5 is a view showing the open-celled rigid polyurethane foam molded article 7 after demolding. FIG. 5 (a) is an external perspective view, and FIG. 5 (b) is a sectional view. The open cell ratio and the density were measured for the surface layer 7a and the center 7b, which constitute the portion from the surface of the open-celled rigid polyurethane foam molded article 7 shown in FIG. . Table 1 shows the results. For reference, in the first and second embodiments, compression (first compression)
Thereafter, the compressed material 6 was removed from the mold, and the results of measurement of the open cell ratio were performed on the surface layer portion and the center portion other than 0.5 mm from the surface toward the inside, together with the results shown in Table 1. .

[0084]

Comparative Example 1 For the purpose of comparison, a rigid polyurethane foam molded article of a comparative example was prepared in the same manner as in Example 1 except that the foaming material was injected without freezing, and a molded article was formed from the surface to the inside. The open cell ratio and the density were measured for the surface layer portion constituting the portion up to 0.5 mm toward the center and the other central portion. Table 1 shows the results.

In Comparative Example 1, as in Example 1, the foaming material component mixture was freely foamed, and the gel time, outgassing time, and rise time were measured and completely cured. A polyurethane free foam X was obtained. Note that the density of the obtained free foam X is:
It was 40 kg / m ³ . The weight was 60 kg / m ³ when the foaming raw material of Example 2 was used.

[0086]

Comparative Example 2 For comparison, the same procedure as in Example 2 was conducted except that mica was previously added to the polyol component, dispersed, and the foaming raw material component mixture mixed with the isocyanate component was injected without freezing. A rigid polyurethane foam molded article of a comparative example was produced. However, because the amount of the filler was too large, the foaming raw material components were not uniformly mixed, and an unreacted portion was formed, so that the foam was not formed,
The open cell ratio and density could not be measured.

Also in Comparative Example 2, the foaming raw material component mixture was freely foamed as in Example 2, and the gel time, outgassing time, and rise time were measured. The mixture was not mixed, and an unreacted portion was formed, so that a foam was not formed and measurement was not possible.

Incidentally, the open cell ratio is determined by the AST as described above.
The closed cell rate (Cr) was measured based on M-D1940, calculated by subtracting this value from 100, and evaluated according to the following criteria. (Judgment criteria) ○: Open cell rate of 99% or more △: Open cell rate of 90% or more and less than 99% ×: Open cell rate of less than 90%

[0089]

[Table 1]

[0090]

Examples 3 and 4 and Comparative Example 3 The molded articles obtained in Examples 1 and 2 and Comparative Example 1 were removed from the mold and left for 1 day, and then radiated with far infrared rays at 130 to 150 ° C. Vacuum insulation materials containing a getter agent were manufactured for each of those subjected to a baking treatment for 0.5 hour in an oven (Examples 3, 4 and Comparative Example 3). In addition, as the getter agent, COMBOG manufactured by SAES Getter Japan
10 g of ETTER (trade name) was used per vacuum insulation material. The dimensions of the core material are all 200 mm.
X 200 mm x 15 mm.

The change in thermal conductivity over time of the obtained vacuum heat insulating material was examined. Table 2 shows the results. The thermal conductivity was measured using a thermal conductivity device (trade name: HC-0, manufactured by Eiko Seiki Co., Ltd.).
74) at an average temperature of 10 ° C.

[0092]

[Table 2]

[0093]

According to the production method of the present invention, the open-celled rigid polyurethane foam molded article of the present invention having a unique structure can be produced with high productivity. Further, according to the production method of the present invention, since the foaming raw material component mixture is a powder, uniform injection into the mold becomes possible, and the filling property and the directionality of the foaming cell,
It is possible to obtain an open-celled rigid polyurethane foam having excellent uniformity in foam density. Further, after the foamed raw material component mixture is cooled and solidified and powdered, the filler is dispersed to obtain an open-cell rigid polyurethane foam in which the filler is uniformly dispersed even when a large amount of the filler is used. Can be.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a production process in a method for producing an open-celled rigid polyurethane foam molded article of the present invention.

FIG. 2 is a view showing one example of a foam molding step in the method for producing an open-celled rigid polyurethane foam molded article of the present invention.

FIG. 3 is a view showing an example of a foam molding step in the method for producing an open-celled rigid polyurethane foam molded article of the present invention.

FIG. 4 is a view showing a step of producing a free-foamed body without a compression step using a foaming raw material component mixture of the open-celled rigid polyurethane foam molded article of the present invention.

FIG. 5 is a view showing an example of the open-celled rigid polyurethane foam molded article of the present invention. (A) is an external perspective view,
(B) is a sectional view.

[Explanation of symbols]

11: High pressure foaming machine discharge head 12: Insulated container 13: Foaming material component mixture 14: LN ₂ supply valve 15: LN ₂ 16: Homomixer 17: Stir bar 18: Foaming material component mixture powder 1: Press 2: Upper die 3: Lower mold 4: Foaming raw material component mixture powder 5: Free foam 6: Compressed material 7: Open cell rigid polyurethane foam 7a: Surface layer (0.5 mm thick) 7b: Central part R: Polyol component T: Isocyanate component X: Foam obtained by free foaming without compression

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA84 AC37 BA34 BC01 CC03Z CC04Y CC05X CC06Z DA13 DA32 4J034 BA03 DA01 DF01 DF02 DF11 DG04 DG06 DG14 DJ08 DP12 DP18 EA07 GA06 GA33 HA01 HA02 HB06 HC12 HC52 HC03 HC04 QA03 QB16 QC02 RA15

Claims (6)

[Claims] A foaming raw material component mixture containing a polyol component, an isocyanate component, and a foaming agent is foam-molded to have a communication degree of 99 with a skin layer remaining.
% Or more, wherein the content ratio of the polyol component and the isocyanate component in the foaming raw material component mixture is about 0.1% by equivalent ratio of NCO / OH.
55 to 0.95, a method for producing an open-celled rigid polyurethane foam molded article comprising the following steps (A) to (F): (A) the foaming raw material component mixture in which foaming and curing reactions have not substantially proceeded Is cooled and solidified, and then pulverized to obtain a foamed raw material powder, (B) a step of injecting the foamed raw material mixture powder into a space to be molded, and (C) a foaming reaction of the foamed raw material mixture. Raising the temperature above the temperature,
(D) a step of freely foaming the foaming raw material component mixture,
(E) a first compression step of compressing the free-foamed product in the free-foaming step of the step (D) before its gel time, and (F) the compression of the compressed product obtained in the step (E) before its rise time. A second compression step of further compressing the mixture. 2. The method according to claim 1, wherein the compression in the first compression step of the step (E) is performed by restraining the expansion of the free foam. 3. The second compression in the step (F),
The method according to claim 1, wherein the method is performed immediately after degassing. 4. The compression in the first compression step of (E) is performed by free-foaming the free-foamed product in the free-foaming step of the step (D) without compression in the step (D) before the gel time. The compression in the second compression step of (F) is performed by compressing the compressed material obtained in the step (E) immediately before the rise time thereof, and further, by (D). 10) volume of free foaming without compression in the process
Claims 1 to 3 performed by compressing to ~ 30%.
4. The production method according to any one of 3. 5. The method according to claim 1, wherein the step (G) of dispersing a filler in the foamed raw material component mixture powder obtained in the step (A) is performed before the step (B). The production method according to claim 1. 6. The method according to claim 1, wherein the blowing agent is water.