JPH0596640A - Manufacture of porous object by reactive injection molding and porous object produced by the process - Google Patents

Abstract

PURPOSE:To obtain uniform void cell with high porosity by a method in which a mold is filled with the eluate composed of globular soluble nylon, and reactive injecting solution is poured into the mold, and after polymerizing and curing, the molded object is taken out, and then it is dipped into solvent and the eluate is eluted, thereby forming voids. CONSTITUTION:The bottom force 2a of a mold 2 is filled with the eluate 1 composed of alcohol-soluble globular nylon. Said filling amount is kept at 50vol.% to the volume of cavity. Next, a top force 2b is superimposed on the bottom force, and the mold 2 is heated at 150 deg.C, and then the elute 1 is melted. then the nylon for reactive injection molding is poured from a pouring port 4 and is polymerized and cured in a cavity 3. Next, a molded object 10 is taken out and is dipped into the mythye alcohol in a liquid tank 6, and them it is cleaned by ultrasonic wave. Consequently, the eluate composed of soluble nylon is eluted, and voids 11 are formed at the position of the eluate 1 in the molded object 10.

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 a porous body by reaction injection molding and a porous body produced by the method. More specifically, it does not cause foaming during molding in a mold, A substance that becomes voids is filled at the time of molding in a mold, and the substance is eluted after molding to form voids, which eliminates the danger at the time of manufacturing the porous body and improves safety.

Further, since the porous body is made of polyamide or cyclopentadiene resin which is excellent in impact resistance and heat resistance, it can be effectively used as a material such as an impact resistant cushioning material and a heat insulating material. Polyamide is also effective as a sound absorbing material because it has excellent vibration damping properties.

[0003]

2. Description of the Related Art Conventionally, as a method for producing a polyamide porous material, a mixture of a lactam, an alkali catalyst, a cocatalyst, and an evaporative blowing agent such as benzene, toluene, xylene or a chemical blowing agent such as allyl azide is substantially anhydrous. A method of polymerizing and foaming a lactam by heating in the above state is proposed in JP-A-49-61254 and JP-A-49-48786.

Further, as another method for producing a polyamide porous body, a method for producing a porous body by generating a nonflammable gas by adding a halogenated hydrocarbon (Japanese Patent Laid-Open No. 51-71395).
JP-A-55-4), a method for producing a porous body by generating carbon dioxide by the reaction of a carboxylic acid and an isocyanate (JP-A-55-4).
No. 3125) has been proposed.

[0005]

When the method of causing foaming in the polymerization reaction of lactam by mixing the above-mentioned evaporative foaming agent is used, the vaporized foaming agent is a flammable substance having a low flash point. , There is a risk of explosion in the manufacturing process. Further, when the chemical type foaming agent is used, the vaporized foaming agent is toxic and has a drawback that it adversely affects the human body.

Further, when the above-mentioned other manufacturing method is used,
Although the above risks are reduced, it is difficult to control in terms of expansion ratio, uniformity of foam cells, etc., performance characteristics are not stable, and the apparent specific gravity is also higher than that of evaporative or chemical type foaming agents. There is a problem that only extremely high porous materials can be manufactured.

The present invention is intended to solve the above-mentioned conventional problems, and a reaction injection molding method is adopted without adopting a method of causing foaming during a lactam polymerization reaction accompanied by the risk of explosion and toxicity. A porous body is produced by using the porous body, and the porosity and the void shape can be arbitrarily designed so that the porosity can be increased and the void cells can be made uniform. ..

[0008]

In order to achieve the above-mentioned object, according to the present invention, a mold is filled with an eluent made of soluble nylon having any shape including granular, powdery and fibrous. After injecting the reaction injection solution into the mold to polymerize and cure and take out the cured molded product from the mold, the molded product is immersed in a solvent to dissolve the eluate, and the eluate is present on the existing part. It is intended to provide a method for producing a porous body by reaction injection molding, which is characterized by forming voids.

The eluent made of soluble nylon to be filled in the mold is brought into contact with each other when the mold is filled, and the contact state is continuous to the eluate exposed on the surface,
Alternatively, by raising the temperature of the mold to the reaction temperature of the reaction injection solution, at least the surfaces are melted so that they are in contact with each other and the contact state is continuous to the eluate exposed on the surface, When soaked in a solvent, it melts from the surface side through a continuous contact portion to form voids that become continuous cells.

The soluble nylon may be either alcohol-soluble, water-soluble, or soluble in both alcohol and water. Depending on the characteristics, the solvent that dissolves the eluate consisting of soluble nylon from the molded article is Selected.

The above-mentioned soluble nylon is a commonly used nylon resin which is chemically modified by reacting formaldehyde with methanol so that it has a characteristic of solubility. Hydrogen of an amide bond is converted into a methoxymethyl group (-). CH ₂
OCH ₃ ). By introducing such a methoxymethyl group, the hydrogen bonding ability due to active hydrogen is lost and the crystallinity of nylon is hindered, so that the solubility in a solvent is increased. By increasing or decreasing the substitution rate of the methoxymethyl group, it is possible to obtain those having different physical properties and adjust the softening point and pour point.

The above-mentioned soluble nylon has a wide range of softening point and pour point, for example, AQ-nylon manufactured by Toray and resin manufactured by Teikoku Kagaku Kogyo are 80 to 190 ° C. Therefore, the reaction injection molding temperature of the matrix resin is In line with
In addition, the soluble nylon to be used can be selected according to the shape of the porous body to be produced.

For example, when a soluble nylon having a softening point or a pour point that becomes a molten state in a mold is used, it is uniformly mixed with the reaction injection liquid, and it depends on the filling amount of the eluent and the melt viscosity. It is possible to disperse into different shapes and form voids corresponding to the dispersed state.

If a material that does not melt in the mold is used, the shape and size of the generated void can be specified by designing the shape and size of the eluent made of soluble nylon. It is possible to manufacture a porous body having the same.

Nylon and cyclopentadiene are preferably used as the matrix resin for the reaction injection molding. When the matrix resin is nylon, that is, in the case of RIM nylon, a reaction injection molding method or a monomer casting method in which molten lactams containing a polymerization catalyst and a polymerization initiator are injected into a mold, and the polyamide is polymerized by heating. Is molded by.

As the ω-lactams which are monomers of the above reaction injection molded nylon, α-pyrrolidone, α-piperidone, ω-enanthlactam, ε-caprolactam,
ω-caprylolactam, ω-pelargonolactam, ω-
Examples include decanolactam, ω-undecanolactam, ω-laurolactam, c-alkyl-substituted-ω-lactams thereof, and mixtures of two or more ω-lactams thereof. Further, the ω-lactam can contain an improving component (soft component), if necessary. The soft component is a compound having a functional group that reacts with the initiator used in the molecule and has a low Tg, and a polyether or liquid polybutadiene having a normal functional group is used.

Commercially available raw materials used as the above-mentioned ω-lactams include UBE nylon (U manufactured by Ube Industries, Ltd.).
X-21) etc. It is composed of an A component consisting of an alkali catalyst and caprolactam, a prepolymer containing a soft component and a B component consisting of caprolactam.

As the above-mentioned polymerization catalyst, sodium hydride is preferable, but other known .omega.-lactam polymerization catalysts such as sodium, potassium and lithium hydride can be used. The amount added is 0 for ω-lactam.
The range of 1-0.5 mol% is preferable.

As the polymerization initiator (activator), N-
Acetyl-ε-caprolactam is used, but other triallyl isocyanurates, N-substituted ethyleneimine derivatives, 1.1′-carbonylbisaziridine, oxazoline derivatives, 2- (N-phenylbenzimidoyl) acetanilide, 2- Compounds such as (N-phenylbenzimidoyl) acetanilide, 2-N-morpholino-cyclohexene-1.3-dicarboxanilide, and known isocyanates and carbodiimides can be used. The addition amount of the above-mentioned polymerization initiator is preferably within the range of 0.05 to 1.0 mol% with respect to the amount of ω-lactam.

When a cyclopentadiene resin is used as the matrix resin, the polymerizable monomer used as the cyclopentadiene resin is a metathesis-polymerizable monomer having a norbornene-type bond.
-Methyl-2-norbornene, 5,6-dimethyl-2-
Norbornene, 5-ethyl-2-norbornene, norbornadiene, synlopentene, dicyclopentadiene,
Dihydrodicyclopentadiene, tricyclopentadiene, methylcyclododecene, methyltetracyclododecene, dimethanehexahydronaphthalene, dimethaneoctahydronaphthalene and the like are used.

As the polymerization catalyst for the cyclopentadiene resin, transition metal compounds such as vanadium, molybdenum, titanium, tungsten compounds, oxyhalide oxides, carbonyls, organic ammonium salts, rhenium and tartan are preferably used.

As the cocatalyst, an alkylaluminum halide, diethylaluminum chloride, ethylaluminum dichloride, an organic tin compound, an alkylaluminum compound, an alkylaluminum halide compound and the like are used.

The present invention further provides a porous body produced by the above-mentioned production method by reaction injection molding. That is, an eluate made of soluble nylon in any shape including granular, powdery, and fibrous is eluted into the inside and the surface of a molded article made of a reaction injection molded polyamide or cyclopentadiene resin after the reaction injection molding. It is intended to provide a porous body including voids formed of continuous cells, which is produced by reaction injection molding in which the volume ratio of the voids is 30 to 95%.

In order to efficiently perform the washing step of dissolving the eluate during the production, a thin plate-shaped open-cell porous body which is eluted at the same time as the immersion in the solvent is provided, and the thin porous body is laminated. Then, a porous body having a required thickness may be formed.

[0025]

According to the manufacturing method of the present invention, in the mold,
An eluent made of soluble nylon is placed in advance in the position of the void portion, and a monomer or prepolymer is injected into the mold to polymerize, and then the molded article is dipped in a solvent to dissolve the eluent. Since the voids are generated by the method, it is possible to eliminate the risk of explosion and toxicity during manufacturing.

The filling amount and shape of the eluent to be filled in the mold,
By adjusting the softening point and the pour point with respect to the mold temperature, the porosity and the void shape can be easily controlled.

The soluble nylon used as the eluent is easily dissolved in water or alcohol. Therefore, by dissolving the soluble nylon in these solvents, voids can be easily formed. Further, the soluble nylon taken out from the molded article after being dissolved can be reused by evaporating the solvent.

[0028]

EXAMPLES Examples of the present invention will be described in detail below. In the first embodiment, an eluate made of granular soluble nylon is used, and at least the surface of the eluate is melted in a mold so that they are in contact with each other to form open cells.

The first embodiment comprises the steps shown in FIG.
First, the granular eluent 1 made of alcohol-soluble nylon is filled inside the cavity 3 provided in the lower mold 2a of the mold 2 ((B) of FIG. 1). The filling amount is set to 50% by weight with respect to the cavity volume. The above alcohol-soluble nylon is Toray's AQ nylon K-80 (melting point 142 ° C)
Made, the particle size is in the range of about 2 mm ² to 4 mm ^2.

Since the eluent 1 is filled in the cavity 3 at a ratio of 50% by weight to the cavity volume as described above, most of the granular eluents are adjacent to each other. It is in contact with the body and is in continuous contact with the eluate exposed on the surface.

After the eluent 1 is filled, the upper mold 2b is replaced with the lower mold 2a.
Then, the mold is closed and clamped ((C) of FIG. 1). After the mold is clamped, the temperature of the mold is raised to 150 ° C. Due to this rise of the mold temperature, the melting point of the eluate 14 filled inside the mold is 142 ° C., so that it melts and various deformations occur in the grain shape.
The eluents 1 have a more dispersed shape and are in a continuous state with each other.

When the temperature of the mold 2 is raised to 150 ° C., nylon for reaction injection molding (UBE Nylon UX-21, Ube Industries Ltd.) is injected through the injection port 4 provided in the upper mold 2b and polymerized inside the cavity 3. -Curing and molding a molded article by reaction injection molding (RIM). After the mold is filled with the reaction injection solution at the time of injection of the reaction injection solution, it is overflowed from the outlet 5.

After curing in the mold to form a molded article,
The mold 2 is released, and the molded product 10 is taken out ((D) of FIG. 1).
The molded article 10 has an eluent 1 made of soluble nylon inside.
Are continuously distributed. The molded product 10 is immersed in a liquid tank 6 containing a solvent composed of methyl alcohol and ultrasonically cleaned for 15 minutes. ((E) in Figure 1)

By the above washing, the eluent 1 made of soluble nylon is melted out from the exposed portion on the surface, and the portions in contact with each other are located inside the molded article 10 as elution passages. The eluent 1 can also be dissolved.

At the portion where the eluent 1 is melted out, that is, at the position where the eluent is present, a void 11 is formed, and this void 11 becomes an open cell. In this way, as shown in FIG.
The porous body 12 made of RIM nylon having the voids 11 in the molded product 10 can be prepared. The foamed RIM nylon of Example 1 had an apparent specific gravity of 0.5 g / cm ³ and formed uniform open cells (cells).

The second embodiment uses an eluate made of powdered soluble nylon, and the melting point of the eluate is higher than the temperature when the mold is heated so that the eluate does not melt inside the mold. Is used. Therefore, increase the filling amount of eluent,
All the eluents have contact portions which are in contact with each other in a state where the eluents are not melted and which are continuous to the surface exposed portion.

That is, as shown in FIG. 3, alcohol-soluble nylon (AQ nylon K-90 manufactured by Toray, melting point 185)
(C) is pulverized to a diameter of 1 mm or less, and the powdery eluent 1 is filled in the cavity 3. The filling amount is set to 95% by weight with respect to the cavity volume. Therefore, all of the powdery eluents 1 are in contact with each other and the contact portion is continuous to the surface.

After the eluent 1 is filled, the mold is clamped, and thereafter,
The mold is heated to 150 ° C., the same nylon for reaction injection molding as in the first embodiment is injected, and RIM molding is performed. At that time, since the melting point of the eluent 1 is 185 ° C. and the mold temperature is 150 ° C., the eluent 1 does not melt in the mold.

After molding, the mold is released, the molded product 10 is taken out, immersed in ethyl alcohol, and ultrasonically cleaned for 10 minutes. By this immersion in the solvent, the eluate 1 inside the molded product melts out, and a void 11 is formed in the melted-out portion, and the porous body 12 shown in FIG. 4 is molded. The apparent specific gravity of the foamed RIM nylon of the second embodiment was 0.05 g / cm ³ .
A uniform open cell porous body 12 was formed.

In the third embodiment shown in FIG. 5, the eluent 1 is
Water-soluble nylon (Toray's AQ nylon A-50: melting point 11
(5 ° C.) in the form of a long fiber, which is filled in the cavity 3 of the mold 2 in a state of being intertwined with each other. The filling rate is 70% by volume of the cavity.
Weight% is used.

After the mold is clamped, the temperature of the mold 3 is raised to 120 ° C. to melt the filled eluate 1 so that the eluates are surely brought into contact with each other. Then, the mold temperature was cooled to 70 ° C., and dicyclopentadiene for reaction injection molding (Teijin Hercules Co., Ltd. METTO
N) is injected and RIM molding is performed. After molding, the mold 3 is released, the molded product 10 is taken out, immersed in water and ultrasonically cleaned for 15 minutes. By the washing with this solvent, the eluent 1 made of water-soluble nylon was melted, and the melted portion was the void 11
As a result, foamed dicyclopentadiene is molded. The apparent specific gravity of the porous body shown in FIG. 6 was 0.3 g / cm ³ .

The eluent made of soluble nylon may be filled in the same cavity by combining eluents having different shapes, for example, granular eluents and fibrous eluents in combination. Similarly, eluates having different melting points may be filled so that one eluate is melted in the mold and the other eluent is not melted in the mold.

[0043]

As is apparent from the above description, according to the method for producing a porous body by the reaction injection molding method according to the present invention, the eluate made of soluble nylon is filled in the mold in advance and the reaction is performed. After injection molding, the eluate filled inside the molded product is melted out with a solvent to form a porous body, so that there is no explosion or toxicity that occurs when foaming occurs during the polymerization reaction of the resin solution as in the past. There is no risk of occurrence, etc., and it can be manufactured while ensuring safety.

Further, as the resin, polyamide and cyclopentadiene, which are excellent in impact resistance, vibration damping characteristics, heat resistance, etc., are molded by RIM molding and used, so that they are used as shock absorbing materials, sound absorbing materials, heat insulating materials and the like. It can be used effectively.

Further, by adjusting the filling amount of the eluent, the shape of the eluent, and the melting point, the expansion ratio and the foaming shape can be freely designed, and a porous body having voids as designed can be obtained. I can.

[Brief description of drawings]

FIG. 1 is a process drawing of a first embodiment of the present invention.

FIG. 2 is a perspective view of a porous body manufactured according to the first embodiment.

FIG. 3 is a process drawing of the second embodiment of the present invention.

FIG. 4 is a perspective view of a porous body manufactured according to a second embodiment.

FIG. 5 is a process drawing of the third embodiment of the present invention.

FIG. 6 is a perspective view of a porous body manufactured according to a third embodiment.

[Explanation of symbols]

 1 Eluent 10 Molded product 11 Void

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29K 105: 06 4F C08L 77:00 9286-4J

Claims (5)

[Claims] 1. A mold is filled with an eluent made of soluble nylon having any shape including granular, powdery, and fibrous, and then a reaction injection solution is injected into the mold to polymerize and cure the solution. After removing the cured molded product from the mold, the molded product is immersed in a solvent to dissolve the eluate, and a void is formed in the portion where the eluate is present to produce a porous body by reaction injection molding. Method. 2. The method for producing a porous body according to claim 1, wherein polyamide or cyclopentaciene is used as the resin for the reaction injection molding. 3. An eluent made of soluble nylon to be filled in a mold is brought into contact with each other when the mold is filled, and the contact state is continuous to the eluate exposed on the surface, and when it is immersed in a solvent. 3. The method for producing a porous body according to claim 1, wherein the porous body is melted from the surface side through a continuous contact portion to form voids that become continuous cells. 4. The eluent made of soluble nylon filled in the mold is melted at least on the surface by raising the temperature of the mold to the reaction temperature of the reaction injection solution so as to be in contact with each other and the contact state. Is formed into a continuous state up to the eluate that is exposed on the surface, and when immersed in a solvent, it dissolves from the surface side through a continuous contact portion to form voids that become open cells. One of
The method for producing a porous body according to item. 5. An eluate made of soluble nylon of any shape including granular, powdery and fibrous is formed inside and on the surface of a molded article made of polyamide or cyclopentadiene resin to be subjected to reaction injection molding after the reaction injection molding. A porous body produced by reaction injection molding, which comprises voids formed by elution and formed of continuous cells, and the volume ratio of the voids is 30 to 95%.