JP2565557B2 - Method for producing polyamide composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial 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 ponomer in the presence of a clay mineral to form a composite with a layered silicate that constitutes the clay mineral of polyamide at the molecular level, resulting in mechanical strength. It has also been found that a composite material having excellent heat resistance can be obtained (see JP-A-62-74957).

Furthermore, the present inventors have examined the method for producing the composite material having excellent mechanical strength and heat resistance, and have proposed a production method by a three-step process (Japanese Patent Application No. 62-31682).
See the specification). 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.

Further, the sound inventors have three steps of a step of obtaining a complex in which the organic cation of the lactam is adsorbed on the layered silicate, a step of mixing the complex with a polyamide monomer, and a step of polymerizing the polyamide monomer. A method for producing a polyamide composite material having the following is also proposed (Japanese Patent Application No. 63-25).
2088 specification). In this method, it is necessary to separate the step of obtaining the composite and the step of mixing the composite and the polyamide monomer.

(Problems to be Solved by the Invention) The present invention solves the above problems and provides a more economical and efficient polyamide composite material having excellent mechanical strength and heat resistance as compared with conventional polyamide composite materials. It is intended to provide a manufacturing method.

[Structure of the Invention] (Problems and Actions to be Solved by the Invention) As a result of research, the present inventors have found that by using a specific amount of a specific acid, the complex in the previous application (Japanese Patent Application No. 63-252088) was obtained. The present invention has been completed by finding that the manufacturing step and the polyamide monomer mixing step can be performed in one step.

That is, the method for producing a polyamide composite material of the present invention comprises a cation exchange capacity of 50 to 200 meq / 100 g of a layered silicate, a compound serving as a swelling agent by the action of an acid, a polyamide monomer and a layered silicate. For total ion exchange capacity
The method is characterized by comprising a step of mixing 0.05 to 5 equivalents of an acid having a pka of 0 to 3 in a dispersion medium, and a step of polymerizing the polyamide monomer in the mixture obtained in the above step.

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

First, the mixing process is performed. In this mixing step, a layered silicate, a compound which becomes a swelling agent by the action of an acid (hereinafter,
Simply referred to as "swelling agent") and polyamide monomer,
By bringing them into contact with each other in a dispersion medium at room temperature in the presence of an acid having a pka of 0 to 3, a composite in which a swelling agent is adsorbed on the layered silicate and a polyamide monomer is adsorbed are obtained. It is a process.

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.

Examples of the raw material of the layered silicate include a layered phyllosilicate mineral composed of a layer of Agnesium silicate or aluminum silicate. 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 swelling agent acts as a cation by the action of an acid having a pka of 0 to 3 existing in the mixed character, expands the layers of the layered silicate, and acts to take the polyamide monomer and finally the polyamide into the layered silicate. It has a role to give. When an amino acid or a lactam is used as the swelling agent, they can be used not only as a swelling agent but also as a polyamide monomer as it is. Examples of the swelling agent include amine, amino acid or lactam. it can. More specifically, actor decyl amine _{CH 3 (CH 2) 17 NH} 2, dimethyl octadecylamine _{CH 3 (CH 2) 17 N} (CH 3) 2, trimethyl octadecylamine _{CH 3 (CH 2) 17 N} (CH 3 ) Aliphatic amines such as ₃ ; p-phenylenediamine H ₂ NC ₆ H ₄ NH ₂ , α-naphthylamine (C ₁₀ H
₇ NH ₂ ), p-aminodimethylaniline N (CH ₃ ) ₂ C ₆ H ₄
NH _2, aromatic amines such as benzene _{H 2 NC 3 H 4 -C 6} H 4 NH 2;
4-amino -n- acid _{H 2 N (CH 2) 3} COOH ,, 6- Amino -
n- caproic acid _{H 2 N (CH 2) 5} COOH, 8- aminocaprylic acid _{H 2 N (CH 2) 7} COOH, 10- aminodecanoic acid H ₂ N (C
H ₂ ) ₉ COOH, 12-aminododecanoic acid H ₂ N (CH ₂ ) ₁₁ COOH, 1
4-amino-tetradecane acid H ₂ N (CH _{2) 13} COOH, 16- amino hexadecanoic acid H ₂ N (CH _{2) 15} COOH, 18-amino-octadecanoic acid H ₂ N (CH ₂₎ amino acids such as ₁₇ COOH; Examples thereof include lactams.

The amount of the swelling agent used is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the layered silicate. When it is less than 5 parts by weight, it becomes difficult to adsorb the polyamide monomer to the layered silicate, and when it exceeds 100 parts by weight, when the swelling agent and the polyamide monomer are different, the swelling agent is a heterogeneous component in the composite material. And is not preferable because it lowers the mechanical strength of the composite material. When the swelling agent is also used as it is as a polyamide monomer, it is necessary to consider the amount of the swelling agent used as a polyamide monomer.

The polyamide monomer used in this step is 6-
Examples thereof include amino acids such as amino-n-caproic acid and 12-aminolauric acid, and lactams such as α-pyrrolidone, ε-caplactam and ω-laurinlactam.

The amount of the polyamide monomer used is preferably determined in relation to the weight ratio 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 0.05 to 150 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 0.05 parts by weight, a sufficient reinforcing effect cannot be obtained, which is not preferable. On the other hand, if it exceeds 150 parts by weight, the content of polyamide is relatively reduced and only intercalation compound powder is obtained, and it is difficult to use this as a molded body, which is not preferable.

The acid used to impart the swelling ability to the swelling agent is pka.
Is in the range of 0 to 3. When pka is less than 0, the reaction vessel is corroded, and when it exceeds 3, the amount of released protons is small and it becomes difficult to make the swelling agent into a cation. Examples of the acid having a pka of 0 to 3 include phthalic acid, phosphoric acid, chloroacetic acid, and trichloroacetic acid.

The addition amount of the acid having a pka of 0 to 3 is preferably 0.05 to 5 equivalents based on the total ion exchange capacity of the layered silicate. If it is less than 0.05 equivalent, the amount of protons released is small and the swelling agent does not exhibit swelling ability. If it is more than 5 equivalents, the acid component becomes excessive and the molecular weight of the polyamide after polymerization is lowered.

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, isoflopanol, ethylene glycol, 1,
4-butanediol, glycerin, etc. can be illustrated. 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 the composite 10 obtained in this mixing step.
The amount is preferably 100 to 5,000 parts by weight with respect to 0 part by weight. When the amount of the dispersion medium used is less than 100 parts by weight, the composite and the polyamide monomer cannot be uniformly mixed, and it becomes difficult to adsorb the polyamide monomer to the composite. On the other hand, if it exceeds 5,000 parts by weight, it takes too much time for the dispersion medium to flow out from the composite material in the weight process, which is not preferable.

The treatment method of this mixing step is not particularly limited, and for example,
After the layered silicate is immersed in a dispersion medium containing a swelling agent, a polyamide monomer and an acid having a pka of 0 to 3, the layered silicate is washed to remove the swelling agent, or a swelling agent is used in advance. Ion-exchanged cation exchange resin and layered silicate,
A method of contacting a liquid in which a polyamide monomer is suspended in a dispersion medium and performing ion exchange can be applied.

The temperature during this mixing is not particularly limited,
If the swelling agent is an organic cation of lactam, which has excellent solubility in water, the target complex can be obtained even when mixing and contacting at room temperature.

By the treatment in such a mixing step, a composite of a layered silicate containing a dispersion medium, a swelling agent and a polyamide monomer can be obtained.

In this composite, a polyamide monomer in a molten state or a mixed liquid of a polyamide monomer and a dispersion medium penetrates between the layers of the layered silicate to spread the layer (that is, swell). It is considered that the driving force for this swelling phenomenon is the affinity between the cations of the composite and the polyamide monomer in the molten state or the polyamide monomer and the dispersion medium.

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

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 required, 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 An autoclave equipped with a stirrer was used as a reactor, and 100 g of Yamagata Prefecture montmorillonite (cation exchange capacity: 119 meq / 100 g, occupied area per negative charge: 106)
Å ² ) is dispersed in 3 of water, and ε-caprolactam and phosphoric acid (pka = 2.1) are added to this at the ratios shown in the table, and 60
Stir for minutes. Then, the temperature was raised to 260 ° C. in a nitrogen stream under stirring, the water was distilled off, and then heating was continued for 5 to 6 hours to obtain a polyamide composite material of the present invention.

The obtained composite material was crushed with a hammer mill, washed with hot water, and then vacuum dried. The interlayer distance of the montmorillonite of the composite material after such treatment was measured by the powder X-ray method. Further, a molded product of the obtained composite material was used as a test piece, and a tensile test, a thermal deformation test and an impact resistance test were performed using the test piece. The test method was based on ASTM. The results are shown in the table.

Comparative Examples 1 to 3 Composite materials were obtained in the same manner as in Example 1 except that acetic acid (pka = 4.8) was used as the acid instead of phosphoric acid, and the same test was performed. The results are shown in the table.

Comparative Examples 4 to 6 Composite materials were obtained in the same manner as in Example 1 except that hydrochloric acid (pka = -3) was used instead of phosphoric acid as the acid, and the same test was performed. The results are shown in the table.

Comparative Examples 7-9 100 g of Yamagata Prefecture montmorillonite (cation exchange capacity
119 meq / 100g, occupied area per negative charge is 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. Then, after thoroughly washing with water, suction was carried out using a Buchner funnel to obtain a water-containing complex.
A part of this complex was taken and the water content was measured.
%Met.

Then, 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. Next, under stirring, in a nitrogen stream, the temperature was raised to 260 ° C. to distill water. Thereafter, heating was continued for 5 to 6 hours to obtain a composite material.

Using this composite material, the same tests as in Examples 1 to 3 were performed. The results are shown in the table.

[Effects of the Invention] According to the production method of the present invention, by using a specific acid in the mixing step, the production step can be simplified (the production time can be shortened), which is more economical and efficient. A polyamide composite material can be obtained.

Moreover, both the mechanical strength and the heat resistance of the obtained molded body of the composite material are excellent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akane Okada Akane Okada, Aichi-gun, Nagakute-cho, Aichi 41, No. 1 Yokomichi Yokomichi No. 1 Yokomichi, Toyota Central Research Institute Co., Ltd. Seiji Sakano (56) Reference JP-A-1-9202 (JP, A) JP 63-230766 (JP, A)

Claims (1)

(57) [Claims] 1. A cation exchange capacity of 50 to 200 meq / 100 g
Layered silicate, a compound which becomes a swelling agent by the action of acid,
A step of mixing 0.05 to 5 equivalents of an acid having a pka of 0 to 3 with respect to the total ion exchange capacity of the polyamide monomer and the layered silicate in a dispersion medium, and polymerizing the polyamide monomer in the mixture obtained in the above step A method for producing a polyamide composite material, comprising: