JPH0819230B2 - Method for producing polyamide composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention is a polyamide composite capable of economically and efficiently producing a polyamide composite material having excellent mechanical strength and heat resistance. It relates to a method of manufacturing a material.

(Prior Art) Conventionally, for the purpose of improving mechanical properties of organic polymer materials, addition and mixing of inorganic materials such as glass fiber, calcium carbonate, silicate, and mica have been studied.

As one of them, the inventors of the present invention previously polymerized a polyamide monomer in the presence of a clay mineral to form a composite of the polyamide and the layered silicate constituting the clay mineral at the molecular level, and It has been found that a composite material having excellent heat resistance can be obtained (see JP-A-62-74957).

Furthermore, the present inventors also conducted a study on a method for producing a composite material having excellent mechanical strength and heat resistance.
We have proposed a manufacturing method using a two-step process (Japanese Patent Application No. 62-3164).
(See No. 82). In this production method, a silicate and an organic cation having a carboxyl group as a swelling agent are brought into contact with each other in a dispersion medium such as water, and a composite having a property of being swollen by the monomer above the melting temperature of the polyamide monomer is dispersed in the dispersion medium. A mixing step of mixing the composite with a polyamide monomer; and a polymerization step of heating the mixture in a subsequent polymerization step to polymerize the polyamide monomer in the mixture. To do.

However, in this manufacturing method, it is necessary to set the swelling temperature in the contact step to be higher than 80 ° C. and room temperature, which leads to an increase in manufacturing cost and a decrease in production capacity. There is room for improvement.

(Problems to be Solved by the Invention) As described above, in the method for producing a polyamide composite material having excellent mechanical strength and heat resistance, which comprises a contact step, a mixing step, and a polymerization step, the treatment in the contact step is performed at a high temperature. Since it is necessary, there are problems such as an increase in manufacturing cost and a decrease in production capacity.

Therefore, the present invention aims to solve the above problems, to provide a method for producing a polyamide composite material, which is economically and efficiently, and has excellent mechanical strength and heat resistance as compared with conventional polyamide composite materials. To do.

[Structure of the Invention] (Problems and Actions to be Solved by the Invention) The method for producing a polyamide composite material of the present invention comprises a layered silicate having a cation exchange capacity of 50 to 200 meq / 100 g and a lactam which is a swelling agent. Contacting the organic cation of, in a dispersion medium to obtain a composite in which the organic cation of the lactam is adsorbed to the layered silicate, a step of mixing the composite and a polyamide monomer, and And a step of polymerizing the polyamide monomer in the mixture obtained in the mixing step.

 Hereinafter, the manufacturing method of the present invention will be described for each step.

First, the contact process is performed. The contacting step is a step of contacting a layered silicate and an organic cation of lactam, which is a swelling agent, in a dispersion medium at room temperature to obtain a complex having the swelling agent adsorbed on the silicate. .

The layered silicate used in this process has a cation exchange capacity.
50-200 meq / 100g. If this cation exchange capacity is less than 50 meq / 100 g, the exchange adsorption of the swelling agent will not be sufficiently carried out, and it will be difficult to obtain the target composite material. If it exceeds 200 meq / 100 g, the bonding force between the layers of the layered silicate becomes too strong, and it becomes difficult to obtain the composite material intended by the present invention.

As a raw material of the layered silicate, a layered phyllosilicate mineral composed of a layer of magnesium silicate or aluminum silicate can be exemplified. Specific examples thereof include smectite silicates such as montmorillonite, saponite, beidellite, hectorite, and stevensite, vermiculite, halloysite, and the like, and these may be natural or synthetic.

The layered silicate is preferably pulverized by a mixer, a ball mill, a vibration mill, a pin mill, a jet mill, a crusher, or the like and adjusted in advance to a desired shape and size.

The organic cation of the lactam, which is a swelling agent, has a role of expanding the layers of the layered silicate and a function of giving a force to incorporate the polymer into the layered silicate. The organic cation of lactam is Is a cation represented by. Where X is generally H or CH _3, the group R is generally - (CH ₂₎ n _- in is a alkylene group represented, but the present invention is of course not limited thereto. The organic cation of lactam can be used alone or in combination of two or more. Specific examples of the organic cation of lactam include those derived from lactam shown below.

The dispersion medium serves to facilitate contact with the swelling agent by dispersing the layered silicate. The dispersion medium can be appropriately determined depending on the type of the layered silicate, but it is preferable that the dispersion medium is one in which the layered silicate is uniformly dispersed and which has good compatibility with the swelling agent and the polyamide monomer.

As the dispersion medium, water, methanol, ethanol, propanol, isopropanol, ethylene glycol, 1,4
Examples thereof include butanediol and glycerin. As the dispersion medium, one type can be used, and two or more types can be used in combination.

The amount of the dispersion medium used is preferably such that the dispersion medium is 5,000 parts by weight or less based on 100 parts by weight of the composite obtained in the contacting step. When the amount of the dispersion medium used exceeds 5000 parts by weight, it takes too much time for the dispersion medium to flow out from the composite material in the polymerization step, which is not preferable.

The method of bringing the layered silicate and the organic cation of the lactam into contact is to immerse the layered silicate in a dispersant containing the organic cation of the lactam, and then wash the layered silicate to remove excess organic cation of the lactam. Or a method in which a cation exchange resin previously exchanged with an organic cation of lactam and a liquid in which a layered silicate is suspended in a dispersion medium are brought into contact with each other to perform ion exchange.

The temperature in this contact is not limited at times, but in the present invention, since the organic cation of lactam, which has excellent solubility in water, is used as the swelling agent, the purpose of contact even at room temperature is Can be obtained.

By the treatment in such a contact step, a composite of a layered silicate containing a dispersion medium and an organic cation of lactam can be obtained. This composite has a property of swelling in a molten polyamide monomer and / or a property of swelling in a mixed liquid of a polyamide monomer and a dispersion medium. The swelling in the present invention means that a molten monomer or a mixed liquid of a monomer and a dispersion medium penetrates between layers of the layered silicate to spread the layer. It is considered that the driving force for this swelling phenomenon is the affinity between the cations in the composite and the monomer in the molten state or the monomer and the dispersion medium.

The composite obtained in the contacting step can be subjected to the next step after removing a part or all of the dispersion medium, if necessary.

Next, the mixing process is performed. This mixing step is a step of mixing the composite obtained in the contacting step and the polyamide monomer.

The mixing method is not particularly limited as long as it can uniformly mix both components.

The polyamide monomer used in this step is 6-
Amino acids such as amino-n-caproic acid and 12-aminolauric acid, α-pyrrolidone, ε-caprolactam, ω-
A lactam such as laurin lactam can be exemplified.

The amount of the polyamide monomer used is preferably determined in relation to the contents of the polyamide and the layered silicate in the finally obtained composite material. That is, it is preferable to mix the polyamide such that the layered silicate is 0.1 to 100 parts by weight with respect to 100 parts by weight of the polyamide in the composite material.

If the content of the layered silicate in the composite material is less than 0.1 part by weight, a sufficient reinforcing effect cannot be obtained, which is not preferable. On the other hand, if the amount exceeds 100 parts by weight, the content of the polyamide is relatively reduced and only the intercalation compound powder is obtained, and it is difficult to use this as a molded body, which is not preferable.

Next, the polymerization process is performed. This polymerization step is a step of obtaining a composite material by polymerizing the polyamide monomer in the mixture obtained in the mixing step.

The polymerization method and the polymerization conditions differ depending on the type of the monomer, but no special method and conditions are necessary, and known polymerization methods and conditions for polyamide monomers can be applied.

Further, in the polymerization step, various polymerization catalysts, polymerization accelerators and the like can be added as required.

The composite material thus obtained is composed of polyamide and a layered silicate uniformly dispersed in the polyamide. The layered silicate has a layer thickness of 7 to 12Å,
The interlayer distance of the silicate is 20 Å or more, and the polymer chain of the polyamide and the layered silicate are ionically bonded.
The interlayer distance means the distance between the centers of gravity of the flat silicate slabs.

The composite material obtained by the production method of the present invention can be used by molding by direct injection molding, heat and pressure molding, or the like. Further, a molded body can be manufactured by carrying out the polymerization reaction in the above-mentioned polymerization step in a predetermined mold.

(Examples) Examples 1 to 3 100 g of Yamagata Prefecture montmorillonite (cation exchange capacity
119 meq / 100g, negative charge-occupied area per valence 106Å
² ) is dispersed in 3 of water, 26.9 g of ε-caprolactam and 24.1 g of concentrated hydrochloric acid (concentration 36%) are added thereto, and the mixture is stirred at room temperature for 60 minutes.
Stir for minutes. After further thoroughly washing with water, suction was carried out using a Buchner funnel to obtain a water-containing complex. A part of this composite was sampled, and the water content (the value obtained by the following formula; water content / water-containing composite; the same applies hereinafter) was 96%. The interlayer distance of the complex of ε-caprolactam and montmorillonite was 15Å.

Next, using an autoclave equipped with a stirrer as a reactor, the water-containing complex was added to ε-caprolactam in a ratio shown in Table 1 (numerical values in the table are parts by weight) and mixed with stirring.

Then, with stirring, in a nitrogen stream, the temperature was raised to 260 ° C. to distill water. Then, heating was continued for 3 to 12 hours to obtain a composite material.

The obtained composite material was crushed with a hammer mill, washed with hot water, and then vacuum dried. The interlayer distance of montmorillonite in the composite material after such treatment was measured by the powder X-ray method. The results are shown in the table.

Further, the obtained composite material was molded into a test piece, and a tensile test, a thermal deformation test and an impact resistance test were performed using this. The test method was based on ASTM. The results are shown in the table.

Comparative Examples 1-3 100 g of Yamagata Prefecture montmorillonite (cation exchange capacity
119 meq / 100g, negative charge-occupied area per valence 106Å
Disperse ² ) in 3 of water, add 51.2 g of 12-aminolauric acid and 24.1 g of concentrated hydrochloric acid (concentration 36%) to this, and add at room temperature for 6
Stir for 0 minutes. However, the same complex as in Examples 1 to 3 was not obtained by such a reaction at room temperature. This is obtained by using the one obtained here, dissolving and polymerizing ε-caprolactam in the same manner as in the example to obtain a composite material, and measuring the interlayer distance of montmorillonite in the material (9.
5 Å) and observation of the dispersion state of montmorillonite with a transmission electron microscope (-layer layers were scattered and not evenly dispersed, and large lumps of about 0.1 to 20 µ were formed).

Therefore, after stirring at room temperature for 60 minutes as described above,
Further, the mixture was stirred at 80 ° C for 60 minutes. Then, after further thorough washing with water, suction was performed using a Buchner funnel to obtain a water-containing complex. Collect a portion of this complex,
The water content was 90%.

Next, using an autoclave equipped with a stirrer as a reactor, the water-containing complex was added to ε-caprolactam at a ratio shown in the table and mixed with stirring.

Then, with stirring, in a nitrogen stream, the temperature was raised to 260 ° C. to distill water. Then, heating was continued for 3 to 12 hours to obtain a composite material.

Using this composite material, the interlayer distance was measured in the same manner as in Examples 1 to 3, and a tensile test and the like were further performed. The results are shown in the table.

As described in Examples 1 to 3, since the organic cation of lactam is used as the swelling agent in the production method of the present invention, the treatment in the contact step can be performed at room temperature without heating. On the other hand, in Comparative Examples 1 to 3, it is necessary to heat up to 80 ° C.

Further, as is apparent from the table, in the comparative example, the heat distortion temperature did not rise to 153 ° C or higher even if the amount of montmorillonite was increased, whereas in the examples, 165 ° C and about 35 ° C were improved. The strength, elongation, elastic modulus, and impact strength were equal to or higher than those of the comparative example.

[Effect of the Invention] According to the production method of the present invention, since the organic cation of lactam is used as the swelling agent in the contact step, the swelling temperature can be lowered. Further, according to the production method of the present invention, a polyamide composite material having excellent mechanical strength and heat resistance can be obtained economically and efficiently.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akane Okada Akane, Aichi Prefecture, Nagakute-cho, Aichi Prefecture, Nagatoji, 1 41, Yokomichi, Toyota Central Research Institute Co., Ltd. (56) Reference JP-A-51-109998 (JP, A) ) JP-A-62-74957 (JP, A) JP-A-64-9202 (JP, A)

Claims (1)

[Claims] 1. A cation exchange capacity of 50 to 200 meq / 100 g
A step of contacting the layered silicate with the organic cation of lactam as a swelling agent in a dispersion medium to obtain a complex in which the organic cation of lactam is adsorbed on the layered silicate; Mixing the body and the polyamide monomer,
And a step of polymerizing the polyamide monomer in the mixture obtained in the mixing step, the method for producing a polyamide composite material.