JP3133101B2 - Method for producing polyhexamethylene adipamide with low triamine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyhexene having excellent physical properties.
The present invention relates to a method for producing Samethylene Adipamide . More specifically , manufacture of polyhexamethylene adipamide for industrial materials such as tire cords with excellent physical properties such as strength and fatigue resistance
About the method .

[0002]

2. Description of the Related Art As a method for producing polyhexamethylene adipamide, for example, as described in US Pat. No. 3,562,206, a 50% by weight aqueous solution of hexamethylene ammonium adipate salt (hereinafter referred to as AH salt) is used. A method has been employed in which the polymer is concentrated and melt-polymerized to obtain a prepolymer, which is then subjected to solid-phase polymerization.

[0003] However, in such a method, bishexamethylenetriamine (hereinafter referred to as BHT) that causes branching of the polymer molecular chain is generated. Since this BHT has three reactive groups, it undergoes a polymerization reaction in three directions to cause branching in the polymer molecule. As the reaction proceeds further, the molecules form a network, and the molecules become three-dimensional and form a gel.

[0004] For this reason, the physical properties of the polymer, such as viscoelasticity, are affected. In addition, a fiber or a molded body using this polymer is affected by its physical properties, for example, the fatigue resistance and the like are reduced. Further, when a molded body is produced using this polymer, for example, in the production of fibers, if BHT is present in the polymer molecular chain, unevenness in viscosity occurs, and cut yarns and fluff are generated. For this reason, a polymer with less BHT has been demanded.

As a method for reducing BHT, a method as disclosed in Japanese Patent Application Laid-Open No. 2-99610 has been disclosed. First, a polymer having a formic acid relative viscosity of 70 or less is produced by a melt polymerization method.
This is a method in which solid phase polymerization is performed at a relatively low temperature of 0 to 240 ° C. until the formic acid relative viscosity becomes 80 or more. However, according to this method, BHT in the polymer was only about 2 mol / kg (430 mg / g) as described therein.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide strength,
Po Li hexamethylene adipamide where properties such as fatigue resistance superior
An object of the present invention is to provide a method for producing a mid .

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the relationship between the molecular chain structure of polyhexamethylene adipamide and the physical properties of the fibers and molded articles thereof. I found that there is a close relationship with physical properties of the body. Further, as a result of a detailed study of the formation process of BHT, it was found that BHT is formed due to the contribution of moisture in the early stage of the polymerization process having a large amount of amino terminal groups, and the formation of BHT is further enhanced when a copper compound is present. The present invention was found to be remarkable and led to the present invention.

That is, according to the present invention, the content of a copper compound is set to 3
In a method of melt-polymerizing polyhexamethylene adipamide of 0 ppm or more, a copper compound is added at a water content of 15% by weight or less in a polymerization system.
Bishexamethylene triamid contained in polymer molecules
Wherein the amount of polyhexamethylene adipamide is 0.4 mg or less per gram of polymer .

The hexamethylene adipamide used in the present invention has a molecular chain repeating unit of --NH (CH ₂ ) ₆ NHC
Polyhexamethylene adipamide consisting of O (CH ₂ ) ₄ CO—. Although the molecular weight is not particularly specified, fibers,
In the molded article, the number average molecular weight is 10,000 to 30,000
Is preferred. The copolymer component may be contained in less than 15%. As other components that can be copolymerized, for example, ε-capramide, polyhexamethylene sebacamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polyxylene phthalamide, and the like may be copolymerized.

The copper compound used in the present invention includes cuprous iodide, cuprous bromide, cupric bromide, cuprous chloride, cupric chloride, copper acetate and the like. It is necessary that the amount of the copper compound in the polymer is 30 ppm or more as a copper element. When the content of the copper element is less than 30 ppm, the effect as a heat stabilizer is small.

The stabilizer may be an alkali or alkaline earth metal halide such as potassium iodide, potassium chloride, sodium iodide, sodium bromide, calcium chloride, preferably potassium iodide, together with the copper compound. Is preferred. Furthermore, inorganic and organic phosphorus compounds, for example, sodium pyrophosphate, sodium phosphite, sodium hypophosphite, triphenyl phosphite, potassium phenylphosphinate, potassium phenylphosphonate, preferably containing sodium hypophosphite in combination It is preferred that

Further, other additives may include a catalyst, a light stabilizer, a pigment, a matting agent, and the like. In the polyhexamethylene adipamide of the present invention, the amount of BHT contained in the molecular chain needs to be 0.4 mg or less per 1 g of the polymer. Preferably, 0.3 to 0.01 m
g / g.

When the content of BHT exceeds 0.4 mg / g, the degree of branching of the polymer molecules increases, and the physical properties of the fiber or the molded product are reduced, for example, the fatigue resistance is reduced. In a molten polymer, the viscosity changes due to branching. For example, when the fiber is drawn by spinning, unevenness in the viscosity of the polymer occurs, thereby causing yarn breakage and fluff. The production method in which BHT is contained in the polymer in an amount of 0.4 mg / g or less will be described below.

After the 50% by weight aqueous solution of AH salt is concentrated to 70% by weight, it is preheated, and the polymerization is carried out while removing water under a pressure of 17.5 kg / cm ² in a reactor. When the water content of the polymerization system becomes 15% by weight or less, a copper compound is added. Thereafter, the pressure is returned to normal pressure, and water is further removed to obtain a predetermined polymerization degree. At this time, when the copper compound is added in the presence of water exceeding 15% by weight, the copper compound becomes BHT
In order to promote the formation of BHT, the content of BHT in the polymer cannot be finally reduced to 0.4 mg / g or less.

Therefore, it is necessary to add the copper compound when the water content in the polymerization system becomes 15% by weight or less. The step of adding is at the end of pressure polymerization, at the time of normal pressure polymerization,
Alternatively, any condition may be used as long as the moisture content is 15% by weight or less, such as at the end of polymerization.

[0016]

The present invention will be described in more detail with reference to the following examples. In addition, the measuring method of each characteristic is shown below. BHT 40 mg of the polymer is placed in a 10 ml glass ampoule, 0.4 ml of 47% hydrobromic acid is added, the atmosphere is sufficiently replaced with nitrogen, and the tube is sealed. This is heated at 150 ° C. for 4 hours to hydrolyze the polymer. After cooling, the glass ampule is opened, evaporated to dryness at 60 ° C. for 4 hours using an evaporator, and further dried at 80 ° C. for 2 hours while reducing the pressure with an oil pump.

To this, as an internal standard, 20 mg of p-terphenyl was added with 50 m of pyridine.
0.2 ml of the solution dissolved in l. Next, N,
O-bis (trimethylsilyl) acetamide (N, O-
bis (trimethylsilyl) acetam
ide) is added thereto, and the mixture is heated at 90 ° C. for 0.5 hour to form a trimethylsilyl derivative.

Furthermore, N-methylbistrifluoroacetamide (N-methylbistrifluoro)
acetamide) at 90 ° C.
Heat for 5 hours to trifluoroacetyl derivatize. This was measured by gas chromatography. Using a previously prepared calibration curve, the amount was determined from the peak intensity of BHT. Copper element 0.1 g of nitric acid is added to 1.0 g of the polymer and heated to dissolve. After cooling, the amount was measured by an atomic absorption method and compared with a calibration curve to determine the amount. Relative viscosity of formic acid (hereinafter referred to as VR) The relative viscosity at 25 ° C. of a solution of 90% by weight formic acid dissolved at a polymer concentration of 11.0 g / dl. Fatigue Resistance A dip cord was embedded in rubber to form a tube, and a fatigue test was performed at 150 ° C. for 120 minutes using the tube by the Goodyear method. Die swell ratio Using Capillograph IB (manufactured by Toyo Seiki Seisakusho), 3
The die swell ratio at 00 ° C., that is, the ratio of the spinning diameter (D0) to the diameter (D) of the discharged polymer 2 mm below the spinning was measured. Moisture content in polymer The moisture content was measured at 150 ° C. using a Karl Fischer moisture meter. Cut yarn ratio 9.5 kg wound, determined by the number of cut yarns at 100 yarns

[0019]

EXAMPLE 1 A 50% by weight aqueous solution of hexamethylene diammonium adipate consisting of equimolar hexamethylene diamine and adipic acid was converted to a 70% by weight aqueous solution in a concentration tank.
Concentrated at 20 ° C. Next, at 230 ° C.
The polymerization was carried out while maintaining the temperature at 17.5 kg / cm ² , and the condensed water was removed by evaporation.
The solution was concentrated to a weight% aqueous solution to obtain a polymer having a VR of 10.

At the outlet of the polymerization reactor, the water content of the polymer was 10% by weight. At this time, an aqueous mixed solution of cuprous iodide and potassium iodide comprising 5% by weight of cuprous iodide and 50% by weight of potassium iodide was measured so that the copper content in the polymer was 80 ppm. 5kg / c
It was added in a pressurized state of m ² . The polymer is then
The pressure was reduced from 7.5 kg / cm ² to normal pressure of 1 kg / cm ² , and the dissolved water was removed by evaporation at 280 ° C. to obtain a polymer having a VR of 32. 0.5 kg / cm
^The pressure was reduced to ² , and the condensed water was removed at 290 ° C. to obtain a polymer having a VR of 80.

As a result of measuring the BHT content of this polymer, it was found to be 0.35 mg / g of the polymer. Also,
The copper content was 78 ppm.

[0022]

Comparative Example 1 An equimolar amount of hexamethylene diammonium adipate comprising hexamethylene diamine and adipic acid was prepared in a 50% by weight aqueous solution in a measuring tank. Copper acetate was added to this aqueous solution so as to be 216 ppm based on hexamethylene diammonium adipate.

This 50% by weight aqueous solution was melt-polymerized in the same manner as in Example 1 to obtain a polymer having a VR of 80. The resulting polymer had a BHT content of 0.73 mg / g of polymer. Further, the copper content was 70 ppm.

[0024]

Example 2 Two kinds of polymers having different BHT contents obtained by different polymerization methods were used to produce a 1890d / 312f tire cord raw yarn by a spin draw take-up method. The obtained fiber had a strength of 10.3 g / d and contained BHT of 0.67 mg / g and 0.38 mg / g, respectively.
mg / g. The yarn breakage rate at the time of manufacture is 10.
2% and 4.8%. As described above, by setting the amount of BHT to 0.4 mg / g or less, the yarn breakage rate was drastically reduced.

[0025]

Example 3 The raw cord of the tire cord obtained in Example 2 was twisted and twisted to obtain a raw cord. This cord was treated with an adhesive to obtain a dip cord. Further, the dip cord was embedded in rubber to form a tube, and the tube was used to examine the fatigue resistance.
The strength of 38 mg / g was improved by 5% as compared with 0.67 mg / g.

[0026]

Example 4 Physical properties of four kinds of polymers having different BHT contents obtained by the present invention and the conventional method were examined. When the content of BHT contained in these polymers was measured, they were 0.29 mg / g, 0.35 mg / g, and 0.50 mg, respectively.
/ G, 0.73 mg / g. The die swell ratios of these polymers are 1.41, 1.43, 1.
52 and 1.55.

Thus, the content of BHT was 0.4 mg.
/ G or less, compared with those exceeding 0.4 mg / g,
Die swell ratio is rapidly decreasing. The die swell ratio indicates the elasticity of the polymer, and the larger the die swell ratio, the worse the spinnability and moldability. Therefore, it is understood that the polymer of the present invention has improved spinnability and moldability.

[0028]

The polyhexamethylene adipamide of the present invention has a uniform melt viscosity during melting. Therefore, when the fiber is spun and drawn using the polyhexamethylene adipamide of the present invention, the generation of cut yarn and fluff is extremely reduced, the yield is improved, or the draw ratio is improved, so that high strength can be realized. And physical properties such as strength and fatigue resistance are improved.

Also in plastic molding, the melt viscosity is uniform, and improvement in moldability and properties can be expected. According to the production method of the present invention, polyhexamethylene adipamide having a very low content of BHT as compared with the conventional one can be obtained.

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Claims (1)

(57) [Claims] 1. A method for melt-polymerizing polyhexamethylene adipamide having a copper compound content of 30 ppm or more as a copper element with respect to a polymer by using an aqueous solution of hexamethylene ammonium adipate salt in a polymerization system. Wherein the copper compound is added at a content of not more than 15% by weight.
The amount of methylenetriamine is 0.4 m / g of polymer
g of polyhexamethylene adipamide.