JPS6241527B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyamide composition containing melamine cyanurate. It is already known that melamine cyanurate imparts an excellent flame retardant effect to polyamide (Japanese Patent Application Laid-Open No. 53-31759). Compared to the method of adding melamine and cyanuric acid separately or in combination to polyamide, this method shows the effect of being able to significantly suppress so-called plate-out and blooming phenomena, but transparency is lost and The inherent properties of polyamide are significantly impaired, such as poor colorability and poor molding fluidity. It also has the disadvantage that weld lines appear on injection molded products, impairing their commercial value. On the other hand, the present inventors have found that by adding melamine and cyanuric acid to polyamide under water-containing conditions during polymerization, a melamine cyanurate-containing polyamide composition can be obtained all at once, and the composition thus obtained can be used in the conventional method described above. It has been found that the dispersion state of melamine cyanurate is essentially a heterogeneous composition with no defects. This method has made it possible to economically advantageously produce flame-retardant polyamide compositions of extremely good quality, but when the reaction is carried out according to the polymerization conditions of ordinary polyamides, There is a problem in that the level does not necessarily increase sufficiently.
This tendency becomes more pronounced as the reaction temperature becomes relatively high, such as in the case of nylon 66, nylon 6, and copolymers mainly composed of nylon 66. An object of the present invention is to solve these problems and provide a method for producing high-quality melamine cyanurate-containing polyamide by increasing the degree of polymerization of polyamide by simple means. The object of the present invention described above is to provide a polyamide-forming monomer with a polyamide-forming monomer of 0.2 to 0.2 to
This is accomplished by heating and reacting 6 mole percent of an organic diamine, melamine, and cyanuric acid in the presence of the amount of water necessary to effect the addition reaction between melamine and cyanuric acid. In the present invention, when an organic diamine is used as a component of a polyamide-forming monomer, the organic diamine in the stoichiometric amount for forming a nylon salt belongs to the polyamide-forming monomer, and the excess amount relative to the stoichiometric amount for forming a nylon salt is the same. Alternatively, a polyamide-forming monomer and an organic diamine are defined as different organic diamines corresponding to organic diamines added separately to the above-mentioned polyamide-forming monomer. In the method of the present invention, well-known lactams, polymerizable ω-amino acids, combinations of diamines and dibasic acids can be used as polyamide-forming monomers, and specific examples include ε-caprolactam. , aminocaproic acid, enantholactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone,
α-piperidone and hexamethylenediamine,
Examples include combinations of diamines such as nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, metaxylylene diamine, and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, and glutaric acid. Ru. Particularly preferred are nylon 66, nylon 6, and copolymer-forming monomers thereof. As the organic diamine added to the polymerization system, aliphatic amines such as hexamethylene diamine, nonamethylene diamine, and dodecamethylene diamine, and aromatic amines such as metaxylylene diamine are generally used, and hexamethylene diamine is particularly preferred. Generally, when a base such as hexamethylene diamine or an acid such as adipic acid is added to a polyamide-forming monomer, the balance of end group groups is disrupted and the degree of polymerization decreases. The addition of hexamethylene diamine, etc., has a remarkable effect on increasing the degree of polymerization. When hexamethylene diamine is added to the production system for nylon 66 polyamide, it is common to the polymerization component, but since the polymerization component is usually used in the form of a salt such as adipic acid hexamethylenediammonium salt, that is, a nylon salt, this article The amount of hexamethylene diamine added in the method of the invention can be easily adjusted. As mentioned above, the amount of these organic diamines added is in the range of 0.2 to 6 mol % based on the polyamide-forming monomer, and if it is out of this range, the degree of polymerization will decrease. The mol% here refers to the polyamide-forming monomer.
Refers to the number of moles of diamine added per 100 moles. When the polyamide-forming monomer is a combination of a diamine and a diacid, 1 mole of each salt is 1 mole, and 1 mole of each of the lactams or aminocarboxylic acids is 1 mole. Melamine and cyanuric acid are added to the polymerization system in substantially equimolar amounts. For example, if one of the two is added in a 1.5-fold molar excess, which cannot be said to be substantially equimolar, the degree of polymerization of the polyamide decreases and causes plate-out and blooming phenomena. Of course, the molar ratio does not necessarily have to be strictly equimolar, and a slight variation, for example, a variation of about 0.1 mole, is allowed as long as the above-mentioned drawbacks do not actually occur. Cyanuric acid includes both enol and keto forms. Melamine and cyanuric acid may be added by any appropriate method, such as adding both in the form of fine powder or in the form of a slurry. It is added before high molecular weight polyamide is produced in the polymerization system, usually when monomers or oligomers are present.
Therefore, the polyamide-forming monomer in the present invention includes not only monomers in the narrow sense as exemplified above, but also oligomers thereof. The amount of melamine and cyanuric acid added is preferably 2 to 25% by weight as melamine cyanurate in the final composition. If it is less than 2% by weight, a sufficient flame retardant effect cannot be imparted, and if it exceeds 25% by weight, it becomes impossible to impart clear coloring using a normal amount of pigment during colored molding, and molding fluidity also decreases. Such shortcomings appear. When carrying out the method of the present invention, the presence of water in the polymerization system is essential. The amount of water is the amount necessary for causing the addition reaction between melamine and cyanuric acid, and is usually added in an amount of 5% by weight or more in the polymerization system. The method of the present invention is carried out by heating such a system, and it is desirable that the heating temperature be in the range of 200 to 300°C and avoid high temperature conditions as much as possible. In addition, in the late stage of polymerization, the system is kept under reduced pressure of 700 mmHg or less for 15 minutes to 2 minutes.
It is particularly preferable to keep the time. The flame-retardant polyamide thus obtained has melamine cyanurate finely dispersed in the polyamide, but it is simply different from a composition obtained by mechanically mixing melamine cyanurate into a separately manufactured polyamide. The dispersed particles differ not only in size but also in shape, and can be said to be completely different compositions. The flame-retardant polyamide of the present invention not only has excellent flame retardancy but also extremely excellent mechanical properties, colorability, and molding fluidity. In addition, the injection molded product has almost no weld lines, which were considered unavoidable in the past, and has extremely high commercial value. Next, the present invention will be explained with reference to Examples. The tests and measurement methods in each example are as follows. (1) Measurement of degree of polymerization of polyamide The relative viscosity ηr of a polyamide solution was determined according to JIS-K6810. (2) X-ray diffraction measurement A flat plate of the sample was molded, and the molded flat plate was placed on a Geigerflex DS model X-ray diffractometer (manufactured by Rigaku Denki) to draw a diffraction pattern in the diffraction angle range of 5 to 40° using a copper target. cyanurate, melamine,
The presence or absence of cyanuric acid was determined by the diffraction peak unique to cyanuric acid. (3) Flame retardancy A UL-94 vertical combustion test was conducted. (4) Mechanical properties The tensile strength of injection molded test pieces was measured according to ASTM-D638. (5) Colorability 97.5 parts by weight of pellets of the test composition were blended with 2.5 parts by weight of nylon pellets of a color masterbatch for black coloring (trade name Leona LCO20-M3300; manufactured by Asahi Kasei Corporation) and injection molded. The degree of blackness of the obtained molded product was observed with the naked eye, and Hunter whiteness was measured using a color difference meter. (6) Weld line To injection mold a rectangular shaped product measuring 5 inches long x 0.5 inches wide x 0.03 inches thick, a mold with gates at each end in the length direction is used, and injection molding is carried out at 250℃. did. The molded product has a central part where the molten resin that flowed from both ends merged, and this part was observed and evaluated with the naked eye. The evaluation ranks were 3: extremely conspicuous, conspicuous, and hardly conspicuous. Example 1 18.0 kg of nylon 66/6 copolymer (hereinafter abbreviated as Ny66/6=88/12) containing 88% by weight of bonding units corresponding to nylon 66 and 12% by weight of bonding units corresponding to nylon 6 was produced. The monomer aqueous solution necessary for
It was prepared by mixing Kg and 2.16 Kg of ε-caprolactam. Next, the monomer aqueous solution was mixed with a monomer concentration of 70% by weight.
concentrated to. Next, the monomer aqueous solution and melamine 988
g (7.8 mol) and 1 kg of water to make a slurry, and 1012 g (7.8 mol) of cyanuric acid to 1 kg of water.
Add Kg of water to make a slurry and inject it.
Furthermore, 103 g of hexamethylene diamine (1 mole % to polyamide-forming monomer) was injected and immediately heated while stirring, and reaction and polymerization were carried out for about 4 hours and 40 minutes while controlling the temperature and pressure. FIG. 1 shows the relationship between temperature, pressure, and time during reaction polymerization.
In the figure, curve 1 indicates the heating jacket temperature, 2 indicates the autoclave internal pressure, and 3 indicates the autoclave internal temperature.
After the reaction and polymerization are completed, the contents are discharged in a molten state in the form of a strand through a die with four 5 mm diameter holes at the bottom of the autoclave, and after cooling with water, cut into 3 mm diameter ×
A polyamide composition was prepared by cutting into 3 mm long cylindrical pellets. The degree of polymerization of the obtained polyamide composition was measured. The result was a relative viscosity ηr=3.0, which was a value sufficient for use as an injection molding material. The composition was also subjected to X-ray analysis. Only melamine cyanurate was detected from the diffraction peak, and melamine and cyanuric acid were not detected. Further, as a result of observing the composition under an optical microscope, it was found that the dispersed particles of melamine cyanurate were extremely uniformly and finely dispersed. Next, the flame retardancy and mechanical properties of the composition were evaluated. The results are shown in Table 1. Comparative Example 1 A polyamide composition was produced under the same composition and reaction conditions as in Example 1, except that hexamethylene diamine was not added. From the polyamide composition,
It was confirmed that melamine cyanurate was sufficiently produced, and the degree of polymerization was a relative viscosity ηr=2.5. The flame retardancy and mechanical properties of the composition were evaluated. The results are shown in Table 1.

[Table] Examples 2 to 4 Using the same polymerization apparatus as Example 1, Ny66/6=90/
Mixing of 50% AH brine, ε-caprolactam, melamine-water slurry, cyanuric acid-water slurry necessary to produce a polyamide composition consisting of 92% by weight of nylon copolymer No. 10 and 8% by weight of melamine cyanurate. The solution was adjusted, and further 0.3 mol% of hexamethylene diamine was added to the polyamide-forming monomer (Example 2), 2.0 mol% to the polyamide-forming monomer (Example 3), and 4.0 mol% to the polyamide-forming monomer (Example 3). Example 4) Reaction polymerization was carried out under the same reaction polymerization conditions as in Example 1. The degree of polymerization of the obtained polyamide composition was measured. The results are shown in Table 2. Comparative Examples 2 to 4 7.0 mol% hexamethylene diamine to polyamide forming monomer (Comparative Example 2), no addition of hexamethylene diamine (Comparative Example 3), 1.0 mol % adipic acid to polyamide forming monomer instead of hexamethylene diamine A polyamide composition was manufactured using the same composition and reaction polymerization conditions as in Examples 2 to 4, except that the polyamide composition (Comparative Example 4) was added, and the degree of polymerization was measured. The results are shown in Table 2.

[Table] Examples 5-6 Comparative Examples 5-6 Equipped with a pressure gauge, pressure regulating valve, and stirrer
A monomer forming 45 g of polyamide, 5 g of an equimolar mixture of melamine and cyanuric acid, and diamine were added in the amounts shown in Table 3 to a 200 ml pressure-resistant autoclave, and the usual polyamide polymerization conditions shown in Table 3 were carried out in the presence of water. The reaction and polymerization were carried out. The resulting composition was subjected to X-ray analysis to examine the presence of melamine cyanurate. Furthermore, the degree of polymerization of the polyamide of the composition was measured. The results are shown in Table 3.

【table】

[Table] Example 7 Using the reaction polymerization apparatus of Example 1, the polymerization temperature and pressure were adjusted as shown in FIG.
A polyamide composition was produced with the same composition and under the same conditions as in Example 1, except that a reduced pressure of 300 mmHg was maintained for 1 hour from 40 minutes to the end of the reaction. When the degree of polymerization of the obtained composition was measured, the relative viscosity ηr was 3.2. Comparative Example 7 Ny66/6 with ηr=3.0 using the same equipment as Example 1
=88/12 nylon 66/6 copolymer pellets were produced. The polyamide pellets weigh 9.0Kg and have an average particle size of 3
Premix 1.0 kg of μ melamine cyanurate powder, feed it to a 40 mmφ extruder, extrude it into strands at an extrusion temperature of 265°C, cool it with water, cut it with a cutter, and
A polyamide composition in the form of pellets measuring mmφ×3 mm in length was obtained. In this composition, white secondary agglomerated melamine cyanurate particles that were visible to the naked eye were observed. Example 8 The weld lines and colorability of the compositions of Example 1 and Comparative Example 7 were evaluated. The results are shown in Table 4.

【table】 [Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between temperature and pressure and time during reaction polymerization in Example 1 and FIG. 2 in Example 7.

Claims (1)

[Claims] 1 polyamide-forming monomer, 0.2 to 6 mol% organic diamine based on the polyamide-forming monomer,
1. A method for producing a melamine cyanurate-containing polyamide composition, which comprises heating melamine and cyanuric acid in the presence of an amount of water necessary to cause an addition reaction between melamine and cyanuric acid.