JPH037729A - Manufacturing method of polyamide composite material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a polyamide composite material having excellent mechanical strength and heat resistance. More specifically, the polyamide and the layered silicate constituting the clay mineral are uniformly bonded to each other through ionic bonds, and the composite material in which they are uniformly combined can be manufactured without corroding the manufacturing equipment, etc. Regarding the method.

(Prior Art) Conventionally, it has been widely practiced to add and mix inorganic materials such as calcium carbonate, clay minerals, or mica as fillers to polymeric materials for the purpose of improving the mechanical properties of organic polymeric materials. Ta.

As one of the methods, the present inventors first polymerized a polyamide monomer in the presence of a clay mineral, and by bonding the polyamide and the layered silicate that constitutes the clay mineral at the molecular level, the inventors achieved mechanical strength and heat resistance. It was discovered that a polyamide composite material with excellent properties could be obtained (Japanese Patent Application Laid-Open No. 62-749
No. 57).

This method for producing a polyamide composite material consists of three steps: a contact step, a mixing step, and a polymerization step.

First, in the contacting step, a clay mineral and a swelling agent are brought into contact with each other in a dispersion medium such as water, and a composite having a property of swelling by the polyamide in the monomer at a temperature higher than the melting temperature of the polyamide monomer is formed by contacting the clay mineral and a swelling agent in a dispersion medium such as water. Obtained in a state containing

Next, in a mixing step, the composite is mixed with polyamide monomer. Furthermore, in the polymerization step, the mixture is heated to polymerize the polyamide monomers in the mixture. Thereby, a polyamide composite material in which the layered silicate is uniformly dispersed in the polyamide resin is obtained.

The contact step here is mainly performed by immersing the clay mineral in an aqueous chloride solution containing ions to be adsorbed. However, it is difficult to completely remove the chlorine ions contained in this chloride from the complex by simply washing with water several times, and for this reason, metals in contact tanks, mixing tanks, polymerization tanks, and transport pipes due to chlorine ions A problem arose in that the equipment was corroded.

In order to reduce the chloride ion content to a level that does not cause corrosion problems, batch washing with large amounts of water must be repeated ten or more times, which is extremely inefficient.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for efficiently manufacturing a polyamide composite material with improved elastic modulus, heat resistance, etc., without corroding manufacturing equipment.

(Means for Solving the Problems) The present invention has a cation exchange capacity of 50 to 200 milliequivalents/
A contacting step in which 100 g of layered clay mineral, a compound that becomes a swelling agent when used in combination with an acid, and a weak acid with a pKa of 2.0 to 5.0 are brought into contact to form a composite, and the composite and a polyamide monomer are brought into contact with each other. This is a method for producing a polyamide composite material, which comprises a mixing step of mixing a polyamide monomer and a polymerization step of polymerizing a polyamide monomer in the mixture.

Embodiments of the present invention will be described in more detail below.

In the contacting step, first, a layered clay mineral having a cation exchange capacity of 50 to 200 milliequivalents/100 g is dispersed in a dispersion medium. On the other hand, by using an acid in combination, a compound that becomes a swelling agent (hereinafter referred to as a "swelling compound") and a weak acid are dissolved in a dispersion medium to form a swelling agent. The clay mineral dispersion is gradually added to this swelling solution while stirring, thereby bringing the clay mineral and the swelling agent into contact with each other. As a result, the metal cations in the clay mineral and the cations of the swelling agent are exchanged, and the molten polyamide monomer or/and
and a composite having the property of swelling in a monomer dispersion. This complex is preferably washed with a dispersion medium in order to remove excess acid, "swelling compounds" or generated salts. If a large amount of acids, "swelling compounds", salts, etc. remain, they may block the ends of the polyamide during polymerization and reduce the molecular weight. Moreover, even if it is a weak acid, if there is a large amount of residual acid, there is a risk of causing corrosion.

Preferably, the clay mineral has a cation exchange capacity of 50 to 200 milliequivalents/100 g and a large contact area with the monomer. Specifically, there are smectite clay minerals such as montmorillonite, saponite, beidellite, nontronite, hectorite, and stevensite, vermiculite, and halloysite, and they may be natural or synthetic.

This layered clay mineral is composed of layered silicates, which provide polyamide with excellent mechanical properties and heat resistance. The layered silicate is a layered phyllosilicate having a layer thickness of 7 to 12 layers of magnesium silicate or aluminum silicate. These layered silicates are negatively charged due to isomorphic ion substitution or the like. Although the characteristics differ depending on the density or distribution of this negative charge, in the present invention, the area occupied by the layer surface per negative charge is 25 to
Preferably, it is a layered silicate of 200 people.

Here, the cation exchange capacity is 50 to 200 milliequivalents/
The reason why it is set at 100 g is because if it exceeds 200 mequivalents/100g, it is difficult to disperse at the molecular level due to the strong bond between the layers of the mineral, and if it is less than 50 mequivalents/100g, This is because exchange adsorption of the swelling agent cannot be performed sufficiently, making it difficult to obtain the desired composite material.

Note that it is preferable that this clay mineral is pulverized using a mixer, a ball mill, a vibration mill, a bottle mill, a jet mill, a beater, etc., to give it a desired shape and size in advance.

Furthermore, the "swelling agent compound" becomes a cation in the presence of an acid, and has the role of expanding the layers as a swelling agent for clay minerals, and the role of providing the ability to incorporate polyamide monomers or polymers between the layers of clay minerals. Consists of one or more of amines, amino acids, or lactams.

Specifically, octadecylamine (CH3 (CH2),
NHt), methyloctadecylamine (CH3(CH2
), NHCH,) or dimethyloccudecylamine (CH3(CH2) ITN (CH,) 2): aliphatic amines such as p-phenylenediamine (NH2C6
H4NH2), α-naphthylamine (C,.H?N
H2), p-aminodimethylaniline (N (CH3
) 2C,84NH2) or benzidine (p N
Aromatic amines such as HiCeH4C6H4NH2p), 4
-Amino-n-butyric acid (NH2Cs HsCOOH), 6
-amino-n-caproic acid (NH, C5H,, C00H
), 8-aminocaprylic acid (NH2C,H,,C00H
), 10-aminodecanoic acid (NH2C, H+aCOOH
), l 2-aminododecanoic acid (NH2C11H2°C
00H), 14-aminotetradecanoic acid (NH2C+
-HweCOOH), 16-amitsuhexadecanoic acid (N
H2C11H2゜C00H) or amino acids such as 18-aminotetradecanoic acid (N Hz C+, Hs-COOH), or αL-pyrrolidone, N-methyl-2-pyrrolidone, δ-valerolactam, ε-caprolactam, N-methylcaprolactam, ω- enantlactam or omega
- Using lactams such as laurin lactum, or a mixture of one or more of these.

It is preferable to use these "swelling agent compounds" in an amount equal to or more than the exchange equivalent of the clay mineral, but since they are relatively expensive, it is better to use a smaller amount.
It is preferable to use about 1.5 equivalents.

The weak acid releases protons to make the "swelling compound" a cation, and its pKa is 2.
A range of 0 to 5.0 is preferred. The pKa of the weak acid is 2.0
If it is less than 5.0, there is a risk of corroding the manufacturing equipment, and if it exceeds 5.0, cations will not be produced sufficiently, and as a result, the ion exchange reaction cannot proceed quantitatively.

Examples of the weak acids include hypophosphorous acid, phosphoric acid, formic acid, acetic acid, chloroacetic acid, propionic acid, butyric acid, benzoic acid, and phthalic acid.

The dispersion medium has the role of facilitating contact with the "swelling agent compound" by dispersing the layered silicate, and is selected depending on the type of clay mineral, "swelling agent compound" and polyamide monomer.

That is, it is desirable that the clay mineral be uniformly dispersed and have good compatibility with the "swelling agent compound" and the polyamide monomer. Examples of the dispersion medium include water, methanol, ethanol, propatool, etc., and one or more of these may be used.

As for the contact method, it is preferable to gradually add the clay mineral dispersion to the swelling solution while stirring. On the contrary, if it is added, quantitative implementation of ion exchange becomes difficult.

It is preferable to wash the composite containing the dispersion medium obtained by this contact step with the dispersion medium to remove excess acid, "swelling compound", salt, etc. Further, a portion of the dispersion medium in the composite may be removed by a suction filtration method, a centrifugation method, a decantation method, or the like. When part of this dispersion medium is removed, the amount of dispersion medium in the composite is preferably 100 to 3000 parts by weight based on 100 parts by weight of the composite. When the content of the dispersion medium is less than 100 parts by weight, it is difficult to mix the composite and the polyamide monomer uniformly in the mixing step described below. Moreover, when it exceeds 3000 parts by weight, it takes too much time to distill off the dispersion medium from the polyamide composite material after the polymerization process.

Next, the composite containing the dispersion medium obtained in the contacting step and the polyamide monomer are mixed (mixing step).

Specific examples of the polyamide monomer include amino acids such as 6-amino-n-caproic acid and 12-aminododecanoic acid; nylon salts such as adipate of hexamethylenediamine, or caprolactam, butyrolactam, capryllactam, and dodecanolactam. It is a lactam such as.

Further, the composite containing the dispersion medium and the polyamide monomer are mixed by mechanical mixing using a stirrer or the like.

The mixture obtained in the mixing step may be directly subjected to the polymerization step, or the dispersion medium in the mixture may be distilled off before use. To distill off the dispersion medium, there is a method of heating the mixture in a nitrogen stream. For example, when the dispersion medium is water,
Preferably, it is heated to 220°C.

Next, the polyamide monomers in the mixture obtained in the mixing step are polymerized to form a polyamide composite material (polymerization step).

The polymerization method and conditions for this polyamide monomer vary depending on the type of monomer, etc., and if necessary, various polymerization catalysts,
A polymerization accelerator or the like may be added.

The polyamide composite material thus obtained consists of polyamide and a layered silicate uniformly dispersed in the resin, and the layer thickness of the layered silicate is 7 to 12, and the interlayer distance of the silicate is 30 Å. This is the result of ionic bonding between a part of the polymer chain of polyamide and the layered silicate.

Here, the content of silicate in the polyamide is preferably 0.05 to 150 parts by weight based on 100 parts by weight of polyamide. If the amount is less than 0.005 parts by weight, the amount of silicate is too small to provide a sufficient reinforcing effect, and
If the amount exceeds 150 parts by weight, the polyamide component is so small that only an intercalation compound powder is obtained, which is difficult to use as a molding material.

This polyamide composite material has a structure in which ammonium ions and the like are ionicly bonded to layered silicate, which is a constituent unit of negatively charged clay minerals, and the ammonium ions are covalently bonded to the main chain or side chain of the polyamide. are doing.

Further, the polyamide composite material obtained according to the present invention may be used after being molded by direct injection molding, heating and pressure molding, or the like. Alternatively, the molded article may be obtained by allowing the above polymerization reaction to proceed in a predetermined mold.

(Effects of the Invention) Since the method for producing a polyamide composite material of the present invention uses a weak acid in the contacting step, the washing operation can be simplified and the production equipment will not be corroded.

Furthermore, the polyamide composite material produced according to the present invention is a polyamide composite material with excellent mechanical strength, elastic modulus, etc., since the produced polyamide does not deteriorate due to residual acid.

(Examples) Example 1 100 g of montmorillonite from Yamagata Prefecture (cation exchange capacity: 119 meq. 7,100 g, negative charge - occupied area per valence: 106 persons 2) was dispersed in 2.3j2 of water at 95°C. On the other hand, 28 g (1.1 equivalent to the exchange equivalent of montmorillonite) of 12-aminododecanoic acid and 23 g (1.1 equivalent to the exchange equivalent of montmorillonite)
3 equivalents to 2-aminododecanoic acid) of acetic acid (pKa
4.8) was dissolved in 500-degree water at 95°C.

The montmorillonite aqueous dispersion was gradually added to the 12-aminododecanoic acid-acetic acid aqueous solution with stirring, and stirred for about 10 minutes while maintaining the temperature at 95°C. After suction filtration with Buchner filter, 3! The composite was washed with boiling water to obtain a hydrated composite.

In this hydrated composite, 80mm x 30mm x 1
A portion of a 5mm mm 5US304 stainless steel test piece was cut into pieces, left at room temperature for 24 hours, and the state of corrosion was observed.

Further, after freeze-drying the composite in a water-containing state, the organic/inorganic content ratio was determined by the burn-residue method, and the ion exchange rate (%) was calculated using equation (2).

Here, 0.264 is (organic matter) at 100% exchange rate calculated from Kunivia F exchange volume ■
Table 1 shows the (inorganic substance) quantitative ratio, organicization conditions for montmorillonite, ion exchange rate, and corrosion test results.

Next, using an autoclave equipped with a stirring device as a reactor, 100 g of ε-caprolactam and the above water-containing complex were added in the proportions shown in Table 1. Under stirring and nitrogen flow,
The temperature was raised to 180°C and water was distilled off. When the water content is 0.5 parts by weight with respect to 100 parts by weight of monomer,
The autoclave was sealed and heated at 250°C for 2 hours. Heating was continued again at 250° C. for 3 to 12 hours under a nitrogen stream to produce a polyamide composite material. Regarding this product, the interlayer distance of the silicate was measured by powder X-ray diffraction method. In addition, the obtained composite material was molded into a test piece, and a tensile test and a thermal deformation test were conducted. The above results are shown in Table 2.

Example 2 The same procedure as in Example 1 was conducted except that 0.5 equivalent parts of acetic acid was used instead of 3 equivalent parts in Example 1, and the results are shown in Tables 1 and 2.

Example 3 The same procedure as in Example 1 was performed except that 10 equivalent parts of acetic acid was used instead of 3 equivalent parts in Example 1, and the results are shown in Tables 1 and 2.

Example 4 The same procedure as in Example 1 was carried out except that instead of adding the montmorillonite-aqueous dispersion to the amino acid-acetic acid aqueous solution in the mixing method of Example 1, the amino acid-acetic acid aqueous solution was added to the montmorillonite 5 6 monoaqueous dispersion. The results are shown in Tables 1 and 2.

Example 5 The results are shown in Tables 1 and 2 in the same manner as in Example 1, except that in the contact step of Example 1, only suction filtration was performed without washing with water, and the composite was used.

Example 6 The same procedure as in Example 1 was conducted except that phosphoric acid (pKa, 2.1) was used instead of acetic acid as the weak acid, and the results are shown in Tables 1 and 2.

Comparative Example 1 Instead of using 3 equivalent parts of acetic acid in Example 1, hydrochloric acid (pK
The same procedure as in Example 1 was carried out except that 1 equivalent part of a, -8) was used, and the results are shown in Tables 1 and 2.

Comparative Example 2 The same procedure as in Example 1 was conducted except that carbonic acid (pKa, 6.4) was used instead of acetic acid in Example 1, and the results are shown in Tables 1 and 2.

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Claims (1)

[Claims] 1. Cation exchange capacity is 50 to 200 milliequivalents/100
A contact step of contacting the layered clay mineral of g, a compound that becomes a swelling agent by using an acid together, and a weak acid with a pKa of 2.0 to 5.0 to form a composite, the composite and a polyamide monomer and a polymerization step of polymerizing polyamide monomers in the mixture. 2. The production method according to claim 1, wherein the amount of the weak acid used in the contacting step is 2.0 to 6 equivalents relative to the compound that becomes a swelling agent when used in combination with an acid. 3. The manufacturing method according to claim 1, wherein in the contacting step, the clay mineral dispersion is gradually added to a solution in which a weak acid and a compound that becomes a swelling agent by using an acid together are dissolved in a dispersion medium. 4. The manufacturing method according to claim 1, wherein the composite formed in the contacting step is washed with a dispersion medium.