JP3440485B2 - Method for producing polyamide pellets - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyamide pellets blended with a heat-resistant agent. More specifically, the present invention relates to a method for producing polyamide pellets in which a heat-resistant agent is uniformly adsorbed on a polyamide and blended so as not to fall off in a subsequent step.

[0002]

2. Description of the Related Art Polyamides obtained by polymerizing diamines with dicarboxylic acids and / or lactams are relatively susceptible to oxidative deterioration, especially when they come into contact with oxygen at high temperatures, resulting in marked deterioration of the degree of polymerization. Cause deterioration of various physical properties. As for the antioxidant for preventing the oxidative deterioration of the polyamide, many compounds have been proposed so far, for example, N, N′-diphenyl-
Amine compounds such as p-phenylenediamine, diallyl-p-phenylenediamine and di-β-naphthyl-p-phenylenediamine, imidazole compounds such as 2-mercaptobenzimidazole and benzimidazole, 2
-Thiazole-based compounds such as mercaptothiazole,
4,4'-dihydroxyphenylcyclohexane, 2,
Phenolic compounds such as 2'-methylenebis (4-ethyl-6-tert-butylphenol), organic or inorganic phosphorus compounds such as stearyl phosphate, phosphorous acid or salts thereof, hexaiodobenzene, pentaiodobenzene, etc. Organic halogen compounds, organic copper salts such as copper acetate and copper stearate, copper compounds such as copper chloride and inorganic copper salts such as copper iodide, sodium iodide, potassium iodide, potassium bromide, ammonium chloride, bromide Inorganic halides such as ammonium and sodium bromide are used alone or in combination. Of these, copper compounds are known to exhibit surprisingly excellent effects, and it is also known that the combined use of an inorganic halide increases the antioxidant effect. Further, these inorganic halides have a function of preventing the precipitation of a thermally unstable copper compound, and are generally used together with a copper compound.

As a method of adding these, a copper compound and an inorganic halide to a polyamide, usually, a method of blending polyamide pellets or powder into pellets using a blender, a method of adding polyamide during polymerization, and a method of remelting polyamide Various methods such as a method of adding and kneading are adopted. However, all of these methods have the following drawbacks. That is, in the powder blending method, the size and shape of the heat-resistant agent powder influence the uniformity of blending, and a heat-resistant agent having a large powder is unsuitable in terms of blending uniformity. Therefore, it is conceivable to make the heat-resistant agent as fine particles as possible, but the heat-resistant agent adhering to the pellet surface is likely to drop off from the pellet surface due to slight vibration, and the uniformity is impaired. Next, the method of adding the heat-resistant agent at the time of polymerization or the method of adding and kneading at the time of re-melting is good in terms of the uniformity of the heat-resistant agent, but the copper compound is deteriorated due to the heat history at the time of polymerization or re-melting and metal copper or Copper oxide is deposited,
It is not preferable because it deteriorates the operability in the next step and reduces the effectiveness as a heat-resistant agent.

As a method for solving the above-mentioned problems in the conventional techniques, water and an inorganic halide are first added to polyamide pellets or pellets as a first step, and after drying, a copper compound is used as a second step. Japanese Patent Publication No. 54-16543 discloses a method for producing a polyamide composition having improved heat resistance, which comprises adding

However, the above Japanese Patent Publication No. 54-165.
In the method described in Japanese Patent Publication No. 43-43, it is possible to produce a polyamide composition to which an inorganic halide is evenly attached, but a powdery copper compound is added onto dried polyamide pellets or pellets. The copper compound is simply mixed in an impregnated state, and not only is the adhesion not uniform, but it is easy to fall off in the popper and the feeding path during the transfer to the subsequent process and in the subsequent process, and the dropped substance adheres to the side wall and becomes large. After being grown, it was supplied in a lump at once and the quality of the obtained polyamide composition was non-uniform. Further, since the drying treatment is performed between the time of adding the inorganic halide and the time of adding the copper compound, a complicated process is required to obtain the polyamide composition, and there is also a problem in process control. It was

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing polyamide pellets, which solves the problems in the prior art.

[0007]

Means for Solving the Problems The constitution of the present invention is as follows: (1) When a polyamide obtained by polymerizing a diamine and a dicarboxylic acid, and / or a lactam is blended with a copper compound and an inorganic halide as a heat-resistant agent, A method for producing a polyamide pellet , which comprises adding an aqueous solution of a water-soluble copper compound and an aqueous solution of an inorganic halide to a polyamide pellet and mixing them to form copper halide on the surface of the polyamide pellet, and then performing a drying treatment. , (2) The copper compound is copper acetate (1)
The method for producing a polyamide pellet described above.

The polyamide that can be used in the present invention is not particularly limited, and any known polyamide such as nylon 6 or nylon 66 can be used. Also,
Its shape is solid such as pellets, chips, flakes (hereinafter simply referred to as pellets), and polyamide obtained by polymerizing diamine and dicarboxylic acid and / or lactam may be used as it is, You may use the thing containing the adsorption | suction water which dehydrated after extracting with water.

The copper compound in the present invention is soluble in water, for example, cupric chloride, cupric ammonium chloride, cupric bromide, copper nitrate, copper sulfate, cupric acetate, copper formate, etc. can give. Further, as the inorganic halide,
It is soluble in water and examples thereof include alkali metal or ammonium halides such as sodium iodide, potassium iodide, potassium bromide, sodium bromide, ammonium bromide and ammonium chloride. The addition amount of these copper compound and inorganic halide to the polyamide is not particularly limited.

In the method for producing polyamide pellets of the present invention, specifically, the copper compound and the inorganic halide are each made into an aqueous solution. The amount of water added to the copper compound and the inorganic halide is not particularly limited, in the mixing process with the polyamide pellets uniformly adhered to the surface of the pellets in an aqueous solution, to uniformly add the additive, to adsorb I need.

The added copper compound aqueous solution and inorganic halide aqueous solution are sufficiently adsorbed on the polyamide pellets, copper halide is produced on the surface of the polyamide pellets, and penetrates into the inside of the polyamide pellets. The polyamide pellets adsorbing the copper halide are then dried to remove the adsorbed water as a copper compound aqueous solution and an inorganic halide aqueous solution. Drying is performed until the polyamide pellets are melted in a subsequent step so that bubbles are not generated, generally 0.1% or less.

The addition and mixing of the copper compound aqueous solution and the inorganic halide aqueous solution to the polyamide pellets are carried out by a commonly used blender, a rotary dryer or the like. As described above, the polyamide pellets to which the copper compound and the halide obtained by the method of the present invention are added, the copper compound and the halide are integrated to form a copper halide, and the copper halide is a polyamide. Since it has penetrated to the inside of the pellets, the copper compound does not drop off in the polyamide pellet transfer step, the feeding step, and the subsequent step, and the formation of the lump copper compound is eliminated, and homogeneous polyamide pellets can be obtained.

Further, since copper compound deposits do not occur in the route of the feeding process or the like, continuous operation is possible for a long period of time, productivity is remarkably improved, process control is facilitated, and a yarn obtained in a post process is obtained. There is no variation between single yarns of the thread and variation in the length direction. In the case of a film, fish eyes are significantly reduced.

[0014]

【Example】

Example 1 Relative viscosity 2.70 (2% with a 1% solution of 98% by weight sulfuric acid)
Nylon 6 pellets (diameter 2.0 mm, length 3.5 mm, water content 12.5%) dehydrated after hot water treatment)
Charge 100 kg into a rotary vacuum dryer with a capacity of 300 L,
Next, 600 g of a 5 wt% cupric acetate aqueous solution-hydrate and 430 g of a 50 wt% potassium iodide aqueous solution were added, and the drier was operated at room temperature and atmospheric pressure for 1 hour at a rotation speed of 5 times / min. An aqueous cupric acetate solution and an aqueous potassium iodide solution were adsorbed on nylon 6 pellets. Then, the dryer was gradually heated to 180 ° C. and dried in vacuum for 15 hours to carry out solid phase polymerization.

The nylon 6 pellets obtained had a relative viscosity of 3.25 and a water content of 0.020%. Further, the concentration of copper (Cu) and potassium (K) in each of the nylon 6 pellets was measured by an atomic absorption method. Result is,
As shown in Table 1, the dispersion of the additive was extremely small and uniform. Further, the obtained pellets were air-transferred using a transfer tube made of a stainless steel tube, and the residual ratio of Cu and K after passing through the powder separator (the Cu before transfer)
The ratio of Cu concentration and K concentration after transfer to the concentration and K concentration) was investigated. The results are as shown in Table 1, the residual rate was very large, and almost no Cu or K was removed. Example 2 Relative viscosity 2.80 (2% with a 1% solution of 98% by weight sulfuric acid)
Nylon 66 pellets dehydrated after hot water treatment (weight 30 mg per pellet, water content 0.40)
%) 100 kg was charged into a rotary vacuum dryer having a capacity of 300 L, and then 600 g of a 5 wt% copper acetate aqueous solution and 30%
A 450% by weight aqueous solution of potassium bromide was added, and a dryer was operated at room temperature and atmospheric pressure for 2 hours at a rotation speed of 5 times / minute to adsorb the copper acetate aqueous solution and the potassium bromide aqueous solution on the nylon 66 pellets. . After that, the dryer was gradually heated to 170 ° C., and in a vacuum state, a drying treatment and a solid phase polymerization were performed for 10 hours.

The nylon 66 pellets obtained had a relative viscosity of 3.60 and a water content of 0.025%. Further, the concentration of copper (Cu) and potassium (K) in each of the nylon 66 pellets was measured by an atomic absorption method. The results are as shown in Table 1, and the variation in adhesion of the additives was very small and uniform. Further, the obtained pellets were air-transferred using a transfer tube made of a stainless steel tube, and the residual ratio of Cu and K after passing through the powder separator (Cu concentration before transfer, Cu concentration after transfer relative to K concentration) , K concentration ratio). The results are as shown in Table 1, the residual rate was very large, and almost no Cu or K was removed. Comparative Example 1 100 kg of nylon 6 pellets used in Example 1 was charged in a dryer having a capacity of 300 L in the same manner to obtain 50% by weight.
430 g of an aqueous potassium iodide solution was added, and the dryer was operated at room temperature under normal pressure for 1 hour at a rotation speed of 5 times / minute. Next, the temperature was raised and the system was operated in vacuum. At this time, the maximum temperature reached by the dryer was 180 ° C., and the dryer was operated for 15 hours. After cooling to room temperature, 30 g of cuprous iodide powder was added, and operation was performed at room temperature under normal pressure for 1 hour at a rotation speed of 5 times / minute. The Cu and K concentrations of each pellet obtained in the same manner as in Example 1 were measured by the atomic absorption method, and the residual ratios of Cu and K after passing through the powder separator were examined. It was as shown. Compared to Example 1 of the present invention, the variation in adhesion of the copper compound was large and the copper compound was easily removed.

[0017]

[Table 1]

[0018]

According to the method for producing a polyamide pellet of the present invention, a copper compound and an inorganic halide are uniformly adsorbed on the polyamide pellet, which is obtained when the polyamide pellet is formed into a yarn in a subsequent step. Since copper halide is uniformly mixed in the yarn, it is possible to obtain a stable and high-quality product with no unevenness in heat resistance in the length direction of the yarn and each single yarn forming the yarn. If so, the production of fish eyes can be significantly reduced. In addition, there is no drop of copper compound from the polyamide pellets, no formation of lumps and deposits of copper compound, the cleaning interval of the pellet transfer process is lengthened, and continuous operation for a long period of time is possible, significantly improving productivity. Has the effect.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI C08L 77/00 C08L 77/00 (58) Fields investigated (Int.Cl. ⁷ , DB name) C08J 3/12 C08L 77/00 -77/12 C08J 3/205 B29B 9/16

Claims (2)

(57) [Claims] 1. When a polyamide obtained by polymerizing a diamine and a dicarboxylic acid, and / or a lactam is blended with a copper compound and an inorganic halide as a heat-resistant agent, an aqueous solution of a water-soluble copper compound and an inorganic halide are added to polyamide pellets. A method for producing polyamide pellets , which comprises adding and mixing the aqueous solution of 1. to produce copper halide on the surface of the polyamide pellets, and then performing a drying treatment. 2. The method for producing polyamide pellets according to claim 1, wherein the copper compound is copper acetate.