JP2002020444A - Production method for ultrafine-cell foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an ultrafine-cell foam without the necessity for a high-cost equipment, such as a pressure tank, and without requiring long time for gas dissolution. SOLUTION: This method produces an ultrafine-cell foam by using a foam production apparatus which is equipped with a plurality of pumping means for metering and delivering raw material components necessary for producing a polyurethane or polyisocyanurate foam, a plurality of transport means for transporting the raw material components delivered by the pumping means to the objective site, and a mixing chamber for mixing the raw material components. The method is characterized in that the pressure of at least one raw material component flowing through the transport means is set at 20×102 kPa or higher and that a gas is continuously dissolved into the raw material component flowing through the transport means under a pressure higher than that of the component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ultrafine cellular foam such as a polyurethane foam or a polyisocyanurate foam, and more particularly, to a method for injecting a gas under specific conditions in a process of transporting raw material components. The present invention relates to a method for producing an ultrafine cellular foam.

[0002]

2. Description of the Related Art Conventionally, polyurethane foams or polyisocyanurate foams have been produced using equipment generally called a foaming machine. This apparatus mainly includes a plurality of tanks, a plurality of pumps, a mixing chamber (mixing chamber) for mixing a plurality of raw material components, a raw material transport pipe connecting the tank and the pump, and connecting the pump and the mixing chamber. It consists of transportation piping.

[0003] Polyurethane foams or polyisocyanurate foams are generally produced using polyols, polyisocyanates, foam stabilizers, catalysts and foaming agents as essential components. If necessary, these raw materials may be used in combination of two or more. It is divided into components and manufactured by the above-mentioned equipment called a foaming machine. In this case, two or more components that cause a reaction when mixed are separately charged into a plurality of tanks, injected into the mixing chamber via the respective tanks, pump means, and transport means, and mixed.

By the way, in the above-mentioned foaming machine, a production method for dissolving a gas in each raw material component to form a fine cell foam so as to be supersaturated under a pressure condition of a mixing chamber,
It is known. Specific methods include, for example, 1) a method of dissolving a larger amount of gas by applying higher pressure air or N ₂ gas or the like in each raw material component tank, 2) forcing gas into the raw material transport pipe. Injecting and dissolving or dispersing. 3) By reducing the pressure of the mixing chamber to below normal pressure,
A method in which the gas in the raw material components is supersaturated in the mixing chamber, and the like.

The amount of these dissolved gases is extremely smaller than the amount of CO ₂ gas produced by the reaction between water as a foaming agent and an isocyanate component. Is injected to generate microcellular foam by generating cell nuclei.

On the other hand, the CO ₂ gas generated by the reaction between isocyanate and water or the gas generated by the boiling of the organic solvent is a gas that is successively generated, and the bubble nuclei that have already been generated without generating almost new bubble nuclei. Since it only diffuses into the air and enlarges the bubbles, the function differs from that of the dissolved gas.

Conventionally, a method for forming fine bubbles by applying a higher pressure to a raw material component tank is described in, for example, Japanese Patent Publication No. Sho 61-3.
No. 663 (prior art 1), JP-A-10-58462 (prior art 2) and JP-A-59-10915.

(1) Prior art 1 has a drawback in that the reactive mixture is divided into a plurality of passages when flowing the reactive mixture into the extrusion die, and a small die having a die side surface at the center where a gel is easily formed in a center portion. In order to eliminate the drawbacks resulting from the use of an extruded die composed of an assembly, the reactive mixture is introduced through a single die inlet to complete the extruded die without substantially dividing the interior of the die into two or more. It has been disclosed. However, at a tank pressure of several kg (pressure of gas to be injected) shown in the prior art 1, it is impossible to generate a bubble structure of 100 μm or less / micro so-called microcell.

(2) According to the prior art 2, after the respective components in the two closed containers are saturated with gas, the two components are mixed, and the mixture is subjected to pressure and / or temperature in a mold. It is disclosed that a foamed synthetic resin is produced by reacting while changing. Here, the pressure is 60 to 8 in a closed container.
It is described that a pressure of 0 × 10 ² kPa is applied. In this case, fine bubbles can be realized. However, there are disadvantages that the tank equipment is expensive and a long time is required to sufficiently saturate the gas in the closed container.

(3) Prior art 3 discloses that air or N ₂ gas is simply injected into a piping for transporting a polyol component. However, this method is a general technique used in the production of a general block foam, and in this method, the cell size is at most about 50% (about 150 μm / ke) with respect to a foam to which no gas is injected. Is the limit. In addition to the above technique, there is also a method of using a stirrer in combination to speed up the dissolution. However, this method also has a problem in the bubble size as in the case of the prior art 3.

Further, the method of reducing the pressure of the mixing chamber to a normal pressure or less to make the dissolved gas in the raw material component injected into the mixing chamber more supersaturated requires not only high equipment costs but also a large bubble size. However, there is a disadvantage that it does not become extremely small.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not require expensive pressure-resistant tanks and other facilities, and does not require a long time for gas dissolution. It is another object of the present invention to provide a method for producing an ultrafine cell foam capable of producing an ultrafine cell foam continuously for a long time without using a reduced-pressure mixing chamber facility and without requiring a large-capacity tank.

[0013]

SUMMARY OF THE INVENTION The present invention comprises a plurality of pump means for measuring and discharging a plurality of raw material components necessary for producing a polyurethane foam or a polyisocyanurate foam, and a raw material discharged from the pump means. A method for producing an ultrafine foam using a foam producing apparatus comprising a plurality of transporting means for transporting the components to a target location and a mixing chamber means for mixing the plurality of raw material components, wherein the transporting is performed. The pressure of at least one raw material component flowing through the means is set to 20 × 10 ² kPa (20 kg / cm ² )
A method for producing an ultrafine bubble foam, wherein the gas is continuously dissolved at a pressure higher than the pressure of the raw material components flowing through the transport means in the raw material components in the transport means, as set above. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, the raw material component pressure is set to 20 × 1
The reason why the pressure is set to 0 ² kPa or more is that if it is less than 20 × 10 ² kPa, the effect of generating fine bubbles is small. Further, the raw material component pressure is preferably set to 40 × 10 ² kPa or more, and particularly preferably set to 60 × 10 ² kPa or more.

In the present invention, the gas to be injected into the raw material component may be continuously injected directly into the raw material component in a pipe as a transportation means through a capillary such as glass or metal, or an inorganic or organic open cell. . Although it is difficult to dissolve a large amount of gas in the raw material component by the above method, a large amount of gas can be dissolved in the raw material component by increasing the distance from the injection to the mixing chamber and setting a long gas dissolution time. , The effect of fine bubbles can be increased. Here, as a method of effectively injecting a gas into a raw material component, instead of simply injecting the gas, a gas is dispersed by a dynamic mixer or a static mixer, and a large amount of gas is quickly injected into the raw material component. It is good to dissolve in it. A particularly preferred mixer is a static mixer, which does not leak fluid from a rotating shaft due to the pressure of a high-pressure fluid as in a dynamic mixer. Alternatively, ultrasonic agitation can be used as well.

Examples of the dynamic mixer include a screw type and a pin type, and examples of the static mixer include a screw type and a pin type in which a rectangular plate is twisted 180 ° in opposite directions to the left and right. There is a method in which beads are packed in a tube, and the like. The glass beads method when the raw material component is a low-viscosity liquid, and the screw type when the raw material component is a high-viscosity liquid are preferable in terms of small pressure loss.

In the present invention, the gas to be injected into the raw material components flowing through the transportation means is, for example, air, N ₂ gas,
Argon gas, helium gas, CO ₂ is a gas, and the like, in particular CO ₂ gas is preferable.

In the present invention, the high-pressure endurance tank is filled with high-pressure gas for a long time to dissolve a large amount of gas in the raw material components, and the transportation means between the pump means and the mixing chamber means is not used. In order to dissolve the gas in a short time in the process, a CO ₂ gas which is easily dissolved in a polyurethane foam raw material or a polyisocyanurate foam raw material is preferable. In the case of CO ₂ gas, even when used at 20 × 10 ² kPa or more and below the critical pressure, the bubble refining effect is large,
70 × 10 ² kP in transportation means, especially at pressures above the critical pressure
When mixed in the raw material component flowing above a, cell diameter density cell diameter of several tens [mu] m / Ke approximately in the form of 25~100kg / ^{m 3,} density in the form of 300~700kg / ^{m 3} Can produce an ultra-fine cell foam having a size of about several μm / piece.

Incidentally, carbon dioxide gas foaming is completely different from this.
The technology called liquid CO₂Into the mixing chamber
Foaming technology (the former) or gas in the mixing chamber
CO ₂Although there is a technology to inject gas (the latter),
It should be clearly distinguished from technology. The former is liquefied
CO₂Using foam as a foaming agent
Liquid CO in bubble nucleus₂CO generated from₂Gas diffuses
To grow bubble nuclei. So the bubbles are smaller
Instead, the bubbles are slightly larger,
Low-density polyurethane foam without using solvent-based solvents
Or polyisocyanurate foam production technology.
You. The latter is mainly CO₂The gas is agitated in the mixing chamber
Disperses and reduces the bubble diameter
CO than₂Disperse the gas evenly and allow the entire foam
This is a technique to equalize temper.

The CO ₂ gas of the present invention is dissolved in a large amount in the raw material components, and by rapidly lowering the pressure of the raw material transported at a high pressure in the mixing chamber, the bubble nuclei are instantaneously generated in a large amount. This is a technique completely different from the above-described carbon dioxide gas foaming in that it is intended to generate ultrafine bubbles.

In the present invention, the position where the gas is injected is in the raw material components in the raw material transport means, but specifically, in the middle of the pipe connecting the pump and the mixing chamber. However, as a special case, when the pump and the mixing chamber are integrated, it is conceivable to inject gas into the middle of the part that acts as a pump and the part that acts as a mixing chamber. Included in the range.

In the present invention, the pump means may be one used for general-purpose polyurethane foam, such as a gear pump or a Bosch pump. A Bosch pump is preferable because it sends the raw material components to the mixing vessel at a high pressure. . In the case of a gear pump, sent pressure of the feed components are used in 3 × ¹⁰ 2 kPa~60 × ¹⁰ approximately 2 kPa, in the case of Bosch pump, 30 × ¹⁰ 2 kPa~1
50 × 10 ² kPa is a general use range.

In the present invention, the mixing chamber used may include a mechanically rotating mixer or a simple chamber without a mixer. This is based on the pressure of the raw material components injected into the mixing chamber. In general, when the pressure of the raw material is such that the raw materials to be injected can be sufficiently mixed, it is not necessary to incorporate a mixer.

In the present invention, the gas is injected into the raw material components sent from the pump. In general, the gas is injected into the most frequently used component of the polyurethane foam raw material or polyisocyanurate foam raw material. Is effective. That is, it is injected into a polyol component or a polyisocyanate component. Even if it is injected into a trace component such as a foaming agent or a foam stabilizer, the effect is small.

The polyurethane foam raw material or polyisocyanurate foam raw material used in the present invention does not require the use of special raw materials, and contains general-purpose polyols, polyisocyanates, foam stabilizers, catalysts and blowing agents as essential components. By adding a plasticizer, a filler, a stabilizer and the like as needed, an ultrafine cell foam can be produced.

In the present invention, the polyol used may be a commonly used polyol, and typical types include polyether polyols, polyester polyols, polydiene polyols, and polycarbonate polyols. Typical polyether polyols have two or more functional groups, such as polypropylene glycol, polyethylene glycol, glycerin obtained by addition-polymerizing polyethylene and polypropylene, and polyoxytetramethylene glycol.

Typical polyester polyols include polyester polyols having terminal OH groups by condensation of low molecular weight polyols such as ethylene glycol and diethylene glycol with acids such as dicarboxylic acids, and polylactone polyols.

In the present invention, the polyisocyanate to be used is generally used, and examples thereof include aromatic polyisocyanate, aliphatic isocyanate, and alicyclic isocyanate. Particularly preferred polyisocyanates are aromatic isocyanates, such as, for example, 4,4 ′ diphenylmethane diisocyanate, crude polymethylene polyphenylene polyisocyanate, 2,4 tolylene diisocyanate and / or 2,4 ′
There are 6 tolylene diisocyanates. In addition, modified isocyanates, for example, allohanate-modified, buret-modified or carbodiimide-modified products can also be used.

In the present invention, the foam stabilizer used may be a commercially available one.
A surfactant such as a polyoxyalkylene glycol copolymer or a sulfonated castor oil is used. Also, as the catalyst, in the case of polyurethane foam,
What is used for ordinary urethane foam may be used,
For example, tertiary amines such as triethylenediamine and morpholine, or organic metal catalysts such as stannasoctoate and dibutyltin dilaurate are used. In the case of polyisocyanurate foam, NCO is generally used.
A generally known isocyanurate catalyst having an / OH index of 1.1 or more can be used. For example, 4
Grade ammonium salts, organic acid alkali metal salts and the like are used. Specifically, potassium acetate, sodium acetate, N,
N ', N "-tris (3-dimethylaminopropyl) hexahydro-s-triazine and the like are particularly common.

In the present invention, as a foaming agent used
Reacts with the isocyanate to produce CO 2 ₂Water producing gas
And pentane, hexane, cyclohexane, dichlorometa
Low boiling points such as 1,1-dichloro-1-fluoroethane
Liquids can be used.

In the present invention, any foaming method such as a one-shot method, a prepolymer method and a kwaji prepolymer method can be used as the foaming method. Particularly, in the prepolymer method, a polyol and a polyisocyanate are prepared in advance. Since the reaction is carried out to form a prepolymer having a terminal NCO group, the polyol component is eliminated. In this case, gas injection may be limited to the prepolymer.

In the present invention, the above-mentioned polyurethane foam includes all of flexible polyurethane foam, semi-rigid polyurethane foam and rigid urethane foam generally referred to. The polyisocyanurate foam includes all semi-rigid isocyanurate foams and rigid isocyanurate foams. Further, from the viewpoint of the production equipment, all known production methods such as a slab foam production method, a mold foam production method, a spray foam production method, a sandwich foam production method, and an RIM foaming method are included in the scope of the present invention.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing an ultra-fine cell foam according to one embodiment of the present invention will be described. The numerical values, materials, and the like described in the following examples are merely examples, and do not specify the present invention. First, an apparatus for producing an ultrafine cell foam will be described with reference to FIG. Reference numeral 1 in the figure indicates a polyisocyanate component tank (hereinafter, referred to as a first tank) containing a polyisocyanate component 2. An N ₂ gas cylinder 4 is connected to an upper portion of the first tank 1 via an N ₂ gas pipe 3. The bottom of the first tank 1 is connected to a mixing chamber 8 via a pipe 7 in which a Bosch high-pressure pump (pump means) 5 and a static mixer 6 are interposed. Here, the polyisocyanate component 2 is measured and discharged by the high-pressure pump 5,
It is discharged into the mixing chamber 8 via a pipe (transportation means) 7.

The static mixer 6 has a flow rate control.
Via a carbon dioxide pipe 10 with a mass flow meter 9
Liquefied CO₂A cylinder 11 is connected. This liquefaction
CO ₂CO from cylinder 11₂The gas passes through the carbon dioxide pipe 10
Pass through the mass flow meter 9 to the static mixer 6₂Moth
Is injected and CO₂Gas is diffused and dissolved in raw material components
You. The mixing chamber 8 is rotated by a stirring motor 12.
Rotating blades 13 are arranged. Where the mixing chamber
8, a stirring motor 12, and a rotating blade 13 by a mixing chamber means
Is configured.

The mixing chamber 8 contains, in addition to the polyol component,
A polyol component tank (hereinafter, referred to as a second tank) 15 containing a mixture 14 in which a foam stabilizer, a catalyst, and a foaming agent are appropriately mixed is connected via a pipe 16. here,
The pipe 16 is provided with a gear pump (pump means) 17. The polyol component is measured and discharged by the gear pump 17, is injected into the mixing chamber 8 via the pipe 16, and is discharged from the mixing chamber 8 to react with the polyisocyanate to form a foam. Further, the second tank 1
The 5 top, _{N 2} gas cylinder 19 through the _{N 2} gas pipe 18 is connected.

Next, a case where an ultrafine cell foam is manufactured using the apparatus having the above-described configuration will be described. The polyisocyanate component 2 is sent from the first tank 1 via the pipe 7 to the mixing chamber 8, and the polyol component 14 is sent from the second tank 15 via the pipe 16. On this occasion,
A Bosch high-pressure pump 5 is interposed in the pipe 7 so that the pressure of the polyisocyanate component 2 flowing through the pipe 7 is 50 × 1
The pressure is set to 0 ² kPa or more, and a static mixer 6 is interposed in the pipe 7 to dissolve a large amount of CO ₂ gas in a short time at 60 × 10 ² kPa higher than the pressure of the isocyanate component. On the other hand, a gear pump 17 is interposed in the pipe 16 so that the pressure of the polyol component 14 flowing through the pipe 16 is set to 10 × 10 ² kPa or more.

As described above, in the above-described embodiment, the pressure of the polyisocyanate component 2 flowing in the pipe 7 as a transportation means is increased by the Bosch high-pressure pump 5, and the polyisocyanate component in the pipe 7 is removed from the liquefied CO ₂ cylinder 11. 2 and a large amount of CO ₂ gas are dissolved therein, and the pressure is rapidly reduced to normal pressure in the mixing chamber 8 to generate more bubble nuclei, and several μm / piece to several tens μm / piece. An ultrafine cellular foam can be formed. In particular, by increasing the pressure of the raw material flowing in the pipe 7 and injecting the gas with a critical pressure, the injected gas can be dissolved in a very short time, and further shortened by using the static mixer 6 together. A large amount of gas can be dissolved in raw material components in time,
As a result, a very fine cell foam can be produced.

[0039]

As described in detail above, according to the present invention, there is no need for expensive pressure tanks or other equipment, no long time is required for gas dissolution, and the use of a reduced pressure mixing chamber equipment. Thus, it is possible to provide a method for producing an ultrafine cell foam capable of producing a microcellular foam continuously for a long time without requiring a large-capacity tank. In addition, by using ultra-fine bubbles, a flexible foam can be made more flexible, and a rigid foam can have a lower thermal conductivity. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus used for a method for producing an ultrafine cell foam according to the present invention.

[Explanation of symbols]

1 ... polyisocyanate component tank (first tank), 2 ... polyisocyanate component, 3, 18 ... _{N 2} gas pipe, 4 and 19 ... _{N 2} gas cylinder, 5 ... Bosch high pressure pump (pumping device), 6 ... stationary Mixer, 7, 16 Pipe (transportation means), 8 Mixing chamber, 9 Mass flow meter, 10 Carbon dioxide pipe, 11 Liquefied CO ₂ cylinder, 12 Stirring motor, 14 Mixture, 15 Polyol component Tank (second tank), 17 ... Gear pump (pump means).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 04 B29K 105: 04 F term (Reference) 4F204 AA42 AB02 AG20 AR02 EA01 EB01 EE01 EE02 EE03 EL02 4J034 CA01 CB03 CC03 DA01 DB04 DF14 DG02 DG03 DG04 HA07 HB05 HB06 HB08 HC12 KA04 NA01 NA02 NA03 PA05 QA07 QC01

Claims (4)

[Claims] 1. A plurality of pump means for measuring and discharging a plurality of raw materials necessary for producing a polyurethane foam or a polyisocyanurate foam, and conveying the raw materials discharged from the pump to a target place. A method for producing an ultra-fine foam using a foam production apparatus including a plurality of transporting means and a mixing chamber means for mixing the plurality of raw material components, wherein at least one component flowing through the transporting means is used. The raw material component pressure is set to 20 × 10 ² kPa or more, and the gas is continuously dissolved in the raw material component in the transportation means at a pressure higher than the pressure of the raw material component flowing in the transportation means. A method for producing an ultra-fine foam. 2. The method for producing an ultrafine cellular foam according to claim 1, wherein the pressure of at least one raw material component flowing through the transport means is set to 40 × 10 ² kPa or more. 3. The method for producing an ultrafine bubble foam according to claim 1, wherein a static gas dissolver is used for dissolving the gas in the raw material components flowing in the transport means. 4. The method according to claim 1, wherein the gas is CO.₂Gas
Injected into the raw material components flowing through the vehicle at or above the interfacial pressure,
And at least one raw material component pressure is at least 70.
× 10²Source flowing through transportation means set to kPa or more
CO ₂4. The method according to claim 1, wherein the gas component is dissolved.
A method for producing an ultrafine cellular foam according to any of the preceding claims.