JP3488295B2 - Method for producing reinforced polyamide resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to the production of a reinforced polyamide resin composition comprising a polyamide (nylon 6 or its copolymer) and a layered silicate and having excellent mechanical strength, toughness, heat resistance and dimensional stability. It is about law.

[0002]

2. Description of the Related Art A resin composition in which polyamide is reinforced with a fiber material such as glass fiber or carbon fiber or an inorganic filler such as calcium carbonate is widely known. However, these reinforcing materials have poor affinity with polyamide, and although the mechanical strength and heat resistance of polyamide are improved by blending them, the toughness is lowered and the resin composition reinforced with fibrous material is also used. Then, there is a problem that the warpage of the molded product becomes large.
Moreover, the resin composition reinforced with these inorganic fillers has a problem that the mechanical strength and heat resistance cannot be improved unless a large amount of the filler is blended.

As an attempt to improve the drawbacks of such a reinforced polyamide, a resin composition comprising a polyamide and a clay mineral represented by montmorillonite has been proposed.
For example, in JP-A-62-74957, JP-A-63-230766, JP-A-2-102261, and JP-A-3-7729,
A resin composition composed of polyamide and montmorillonite is disclosed.

This resin composition is intended to form a finely and uniformly dispersed composite by infiltrating polyamide chains between layers of clay minerals. When montmorillonite is used for such a purpose, each of the above publications is used. As described in (1), a treatment for expanding the interlayer distance of montmorillonite was indispensable by contacting it with a swelling agent such as an amino acid before compounding the montmorillonite with the polyamide or the monomer forming the polyamide. . Therefore, there is a strong demand for an inorganic filler that does not require such a treatment and can eliminate the drawbacks of conventional polyamide resins.

As an attempt to solve such a problem, the present inventors have previously proposed a method for producing a reinforced polyamide resin composition by adding a swelling fluoromica-based mineral to a monomer forming a polyamide and polymerizing the same. Proposed (JP-A-6-2481)
No. 76). In this method, unlike the case of using a conventional clay mineral represented by montmorillonite, it is possible to obtain a resin composition excellent in mechanical strength, toughness, heat resistance and dimensional stability without performing a swelling treatment. It was

However, in order to obtain a resin composition having excellent performance, it is necessary to adopt a high-pressure polymerization method in which polymerization is carried out at a pressure of 10 kg / cm ² or more, which requires a special polymerization apparatus. was there.

Further, as a method for solving this problem,
The present inventors have proposed a method of adding a swelling fluoromica-based mineral in the presence of an acid having a pKa of 0 to 6 and polymerizing a monomer that forms a polyamide (Japanese Patent Application No. 6-96).
-142878). In this method, it is not necessary to increase the pressure at the time of polymerization, and a resin composition excellent in mechanical strength, toughness, heat resistance and dimensional stability can be obtained only by using a pressure of about 5 kg / cm ² for suppressing pressure. I was able to.

However, the resin composition obtained by this method does not sufficiently improve the water absorption, which is one of the drawbacks of the polyamide resin composition, and after the water absorption, the dimensions change greatly and the tensile strength greatly decreases. There was a problem.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a reinforced polyamide resin composition by adding a layered silicate to a monomer forming a polyamide (nylon 6 or a copolymer thereof) and polymerizing the monomer. An object of the present invention is to provide a method capable of obtaining a reinforced polyamide resin composition which is excellent in dynamic strength, toughness, heat resistance and dimensional stability, has a low water absorption rate, and does not deteriorate in these properties even when absorbing water.

[0010]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and its gist is polyamide (nylon 6
Or a copolymer thereof) 0.001 to 1 pKa of fluorine mica relative amount of monomers for forming the 0.01 parts by weight of the polyamide relative to the amount of monomers to form a 100 parts by weight of the negative acid
It is a process for producing a reinforced polyamide resin composition, which comprises polymerizing a monomer in the presence of mol%.

The present invention will be described in detail below.

The polyamide targeted by the present invention is nylon 6 and its copolymer, and the monomer forming nylon 6 is ε-caprolactam and / or 6-aminocaproic acid.

The copolymerizable monomer includes various aminocarboxylic acids or lactams and nylon salts, specifically, 11-aminoundecanoic acid, 12-aminododecanoic acid,
Paraaminomethyl benzoic acid, ω-laurolactam, nylon 46 salt, nylon 66 salt, nylon 610 salt, nylon 6T salt, nylon 6I salt, salts of metaxylylenediamine and adipic acid and the like can be mentioned.

In the present invention, when the nylon 6 or its copolymer is produced, the layered silicate is added to the monomer for polymerization.

As the layered silicate in the present invention, natural products and / or synthetic products can be used, and examples thereof include those of the smectite group, the vermiculite group, the mica group, the brittle mica group and the chlorite group.

The ion exchange capacity of the layered silicate is not particularly limited, but an ion exchange capacity of 20 meq / 100 g or more is preferable. When a layered silicate having a large ion exchange capacity is used, a reinforced polyamide resin composition which is excellent in mechanical strength, toughness, heat resistance and dimensional stability, has a low water absorption rate, and is small in dimensional change and strength reduction due to water absorption can be obtained. . The ion exchange capacity can be measured, for example, by the methylene blue adsorption method (“Clay Handbook Second Edition”, Gihodo Publishing, 1987, page 502).

The layered silicate is added in an amount of 0.01 to 100 parts by weight, preferably 0.1 to 20 parts by weight, and optimally 1 to 10 parts by weight per 100 parts by weight of the polyamide produced during the polymerization of the polyamide. To be done. If the content is too small, the effect of improving mechanical strength, heat resistance, and dimensional stability will not be sufficiently exhibited, and if it is too large, the toughness will be significantly reduced.

For the monomers that form the polyamide,
By polymerizing the monomer in the presence of a predetermined amount of the layered silicate and the acid having a negative pKa, the layered silicate is sufficiently finely dispersed in the polyamide, and the effect of the present invention remarkably appears.

The acid used in the present invention has a negative pKa. With an acid having a pKa of 0 or more, as described above, the improvement of water absorption is not sufficient, and the problems of dimensional change and reduction in tensile strength due to water absorption are not solved.

The acid used in the present invention may be an inorganic acid or an organic acid, specifically, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, perchloric acid, fluorosulfonic acid-pentafluoroantimony. (1: 1) [Commercially available from Aldrich under the trade name of "Magic Acid". ],
Examples include fluoroantimonic acid, oxonium salts such as ethanol hydrochloride, ammonium salts such as 2,4,6-trinitroaniline hydrochloride, and sulfonium salts such as dimethyl sulfide hydrochloride.

The acid is added in an amount of 0.0001 to 1 mol%, preferably 0.005 to 0.
It is necessary to set it to 5 mol%. The amount added is 0.0001
If it is less than 1 mol%, the effect is small, and if it exceeds 1 mol%, the acid component becomes excessive, so that a polymer having a high degree of polymerization cannot be obtained and, as pointed out in Japanese Patent Application No. 6-142878, a polymerization vessel is used. Corrosion and other problems may occur.

To carry out the method of the present invention, a predetermined amount of an aqueous solution of a layered silicate and an acid (an aqueous solution prepared by dissolving an acid in water used as a polymerization initiator) is added to a monomer forming a polyamide, Polymerization may be carried out under the conditions similar to the usual polymerization of nylon 6. The layered silicate does not need to be subjected to a swelling treatment in advance, and may be added to the monomer as it is. The pressure at the time of polymerization does not need to be high, and the pressure at the time of suppression may be about 5 kg / cm ² .

Polymerization must be carried out until a resin having a high degree of polymerization is obtained, and sulfuric acid having a concentration of 96% by weight is used as a solvent.
Relative viscosity measured at a temperature of 25 ° C and a concentration of 1 g / dl
It is preferable that the range of 1.5 to 5 be obtained. If the relative viscosity is too small, the mechanical performance of the resin composition is low, and if it is too large, the moldability of the resin composition rapidly decreases, which is not preferable. After the melt polymerization,
Solid phase polymerization may be performed as necessary.

To the reinforced polyamide resin composition, a pigment, a heat stabilizer, an antioxidant, a weather resistance agent, a flame retardant, a plasticizer, a mold release agent, a reinforcing material, etc. should be added as long as the characteristics are not significantly impaired. Is also possible. Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds,
Hindered amines, sulfur compounds, copper compounds, alkali metal halides or mixtures thereof can be used. In particular, copper compounds and alkali metal halides are most effective. As the reinforcing material, for example, clay, talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, asbestos, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, Zinc oxide, antimony trioxide,
Zeolite, hydrotalcide, metal fibers, metal whiskers, ceramic whiskers, potassium titanate whiskers, boron nitride, graphite, glass fibers, carbon fibers and the like can be mentioned. These additives are added during polymerization or during melt kneading or melt molding of the obtained resin composition.

The resin composition obtained by the method of the present invention can be used as a mixture with other polymers. Examples of such polymers include polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, natural rubber, chlorinated butyl rubber, chlorinated polyethylene and the like. Elastomers and acid modified products of these with maleic anhydride, styrene-maleic anhydride copolymer, styrene-phenylmaleimide copolymer, polyethylene, polypropylene, butadiene-acrylonitrile copolymer, polyvinyl chloride, polyethylene terephthalate, polybutylene Terephthalate, polyacetal, polyvinylidene fluoride, polysulfone, polyphenylene sulfide, polyether sulfone, phenoxy resin, polyphenylene ether, polymethylmethacrylate, polyetherketone, po Carbonate, there is polytetrafluoroethylene.

The resin composition obtained by the method of the present invention can be made into a desired molded article by a usual molding method.
For example, a hot melt molding method such as injection molding, extrusion molding, blow molding, and sintering molding, or a method of forming a thin film from an organic solvent solution by a casting method can be adopted.

The resin composition obtained by the method of the present invention is remarkably improved in mechanical strength, heat resistance and dimensional stability as compared with the case of using polyamide alone, and has little change in mechanical properties and dimensions due to water absorption. . This resin composition, due to its excellent performance, mechanical parts and housings such as switches and connectors in the field of electric and electronic devices, underbonnet parts and exterior parts in the field of automobiles, optical parts such as outer plate parts and reflectors, etc. Alternatively, it is used as a gear or bearing retainer in the mechanical field.

[0028]

EXAMPLES Next, the present invention will be described more specifically by way of examples. The raw materials and measuring methods used in Examples and Comparative Examples are as follows. 1. Raw Material (A) Talc pulverized by a layered silicate fluoromica ball mill to an average particle size of 2 μm and fluorinated silica particles shown in Table 1 having an average particle size of 2 μm are mixed at a ratio (parts by weight) shown in Table 1. , Put it in a magnetic crucible and hold it in an electric furnace at 800 ° C for 1 hour,
-2 Fluorine mica was synthesized. X generated fluoromica
As measured by the wire powder method, the thickness of the raw talc in the C-axis direction
The peak corresponding to 9.2Å disappeared, and the peak corresponding to 12 to 16Å indicating the formation of swelling fluoromica was observed. The results of measuring the ion exchange capacity of the obtained fluorine mica by the methylene blue adsorption method are shown in Table 1.

[0029]

[Table 1]

Bentonite (manufactured by Toyojun Yoko Corp., Hotaka seal, ion exchange capacity 75meq / 100g) (abbreviation BN) (B) Hydrochloric acid (concentration 35% by weight) Sulfuric acid (concentration 96% by weight) Fluorosulfonic acid-pentafluoroantimony (1:
1) ("Magic Acid" manufactured by Aldrich) (abbreviation MA) 2,4,6-trinitroaniline hydrochloride (abbreviation TNA) 2. Measurement method (1) Tensile strength and elongation at break It was measured based on ASTM D638. (2) Izod impact strength Measured based on ASTM D256 using a 3.2 mm thick test piece. (3) Heat distortion temperature (HDT) Based on ASTM D648, load 18.6kg / cm ² and 4.5kg / cm ²
It was measured at. (4) Dimensional change Using a square test piece having a thickness of 2 mm and a width of 50 mm, the thickness and the vertical and horizontal dimensional changes due to water absorption treatment were measured, and the average value was taken as the dimensional change. (5) Water absorption rate Using the same test piece as above, it was determined from the weight change after water absorption treatment. The water absorption treatment was performed by treating the test piece for 24 hours under the conditions of 60 ° C. and 95% RH.

Examples 1 to 4 and Reference Example 10 kg of ε-caprolactam was mixed with 1 kg of water, a layered silicate and an acid in the amounts shown in Table 2 and placed in a reactor having an internal volume of 30 liters. , Heat to 260 ℃ with stirring, 5
The pressure was increased to a pressure of kg / cm ² . Then, the pressure was released to normal pressure, and polymerization was carried out at 260 ° C. for 3 hours. At the end of the polymerization, the reaction product was discharged in a strand form, cooled, solidified, and then cut into pellets made of the reinforced nylon 6 resin composition. The pellets obtained are treated with hot water at 95 ° C to be scoured,
Dried. The pellets were supplied to an injection molding machine and injection-molded at a cylinder temperature of 260 ° C and a mold temperature of 70 ° C to form test pieces. Table 2 shows the results of performance evaluation of the obtained test pieces.

[0032]

[Table 2]

Comparative Examples 1 to 5 The pressure during polymerization was 5 kg / kg as shown in Table 3 without adding acid.
Pellets of the reinforced nylon 6 resin composition were obtained in the same manner as in Example 1 except that the polymerization was performed while changing from cm ² to 15 kg / cm ² . A test piece was molded in the same manner as in Example 1, and the results of performance evaluation using the obtained test piece are shown in Table 3.

Comparative Example 4 ε-caprolactam was polymerized in the same manner as in Reference Example except that the amount of acid added was changed to 5 mol%. Due to the large amount of acid, it was not possible to obtain a high molecular weight reinforced nylon 6 resin composition that can be used for molding.

Comparative Example 7 Pellets of a reinforced nylon 6 resin composition were obtained in the same manner as in Example 1 except that phosphoric acid having a pKa of 2.2 was used as the acid. A test piece was molded in the same manner as in Example 1, and the results of performance evaluation using the obtained test piece are shown in Table 3. The obtained resin composition was excellent in mechanical strength, toughness, heat resistance and dimensional stability, but the water absorption was not sufficiently improved, and the water absorption caused a large change in dimensions and a significant decrease in tensile strength. .

[0036]

[Table 3]

[0037]

According to the present invention, a high-pressure polymerization method is used in a method for producing a reinforced polyamide resin composition by adding a layered silicate to a monomer for molding a polyamide (nylon 6 or its copolymer) and polymerizing it. It is possible to obtain a reinforced polyamide resin composition that has excellent mechanical strength, toughness, heat resistance, and dimensional stability, and has a low water absorption rate and a small dimensional change due to water absorption and a reduction in tensile strength become.

Continuation of front page (56) Reference JP-A-2-173160 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 69/00-69/50 C08L 77/00-77 / 12

Claims (2)

(57) [Claims] 1. A fluorine cloud based on the amount of monomers forming 100 parts by weight of polyamide (nylon 6 or its copolymer).
A method for producing a reinforced polyamide resin composition, which comprises polymerizing a monomer in the presence of 0.01 to 100 parts by weight of a mother and 0.001 to 1 mol% of an acid having a negative pKa relative to the amount of a monomer forming a polyamide. . 2. Fluorine mica has a cation exchange capacity of 20 meq / 10.
Preparation of reinforced polyamide resin composition according to claim 1, wherein the above fluorinated mica 0 g.