JP3296140B2 - Method for producing polyamide resin particles containing heat-resistant agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in polyamide resin particles containing a heat-resistant agent. For more information,
Polyamide resin particles containing a heat-resistant agent, high temperature,
The present invention relates to a polyamide resin particle in which oxidative deterioration in a high oxygen concentration atmosphere is suppressed and a method for producing the same.

[0002]

2. Description of the Related Art Polyamide articles such as fibers and resin molded articles using a polyamide resin obtained by polymerizing a diamine and a dicarboxylic acid and / or a lactam have excellent toughness and fatigue resistance. Widely used for industrial materials. However, these polyamide resins and articles made therefrom are relatively susceptible to oxidative degradation, and particularly when exposed to oxygen at high temperatures, are significantly oxidatively degraded, causing a decrease in the degree of polymerization and various physical properties.

Many antioxidant compounds have been proposed as heat resistant agents for preventing the oxidative deterioration of the polyamide. For example, amine compounds such as N, N′-diphenyl-p-phenylenediamine, diallyl-p-phenylenediamine, di-β-naphthyl-p-phenylenediamine, 2-mercaptobenzimidazole,
Imidazole compounds such as benzimidazole, thiazole compounds such as 2-mercaptothiazole, 4,
4'-dihydroxydiphenylcyclohexane, 2,
Phenolic compounds such as 2′-methylenebis (4-ethyl-6-tert-butylphenol), organic or inorganic phosphorus compounds such as stearyl phosphate, phosphorous acid or a salt thereof, hexaiodobenzene, pentaiodobenzene, etc. Organic halogenated compounds, copper acetate,
Copper compounds such as organic copper salts such as copper stearate, inorganic copper salts such as copper chloride and copper iodide, and inorganic compounds such as sodium iodide, potassium iodide, potassium bromide, ammonium chloride, ammonium bromide, and sodium bromide. Halides and the like have been proposed, and these are used alone or in combination.

[0004] Among them, particularly, copper compounds exhibit surprisingly excellent effects, and when used together with inorganic halides, their antioxidant effects are enhanced. The inorganic halide also has a function of preventing the precipitation of a thermally unstable copper compound, and is generally used in combination with a copper compound.

[0005] As a method of adding these copper compounds and inorganic halides to polyamide, a method of mixing powder with polyamide chips or flakes using a blender or the like, a method of adding the polyamide compound at the time of polymerization, and a method of adding and kneading the polyamide at the time of remelting. Various methods such as methods have been adopted.

However, these methods have the following disadvantages. That is, in the powder mixing method, the size and the shape of the heat-resistant agent powder determine the uniformity of the mixing, and the heat-resistant agent having a large powder is inappropriate in view of the uniformity of the mixing. Therefore, a method of making the heat resistant agent as fine particles as possible is conceivable. However, the heat resistant agent adhering to the chip surface is easily removed from the chip surface even with a slight vibration, and the uniformity is deteriorated, which is not a preferable method. Next, the method of adding the heat-resistant agent at the time of polymerization or the method of 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. It is not preferable because copper and copper oxide are apt to be precipitated, which deteriorates the operability in the next step and lowers the effectiveness as a heat-resistant agent.

[0007]

SUMMARY OF THE INVENTION In order to solve these problems, the present inventors first disclosed in Japanese Patent Laid-Open No. 6-256649.
As described in the publication, a method was proposed in which an aqueous solution of a copper compound and an aqueous solution of an inorganic halide were mixed and added to a polyamide to form a copper halide on the surface of the polyamide, followed by a drying treatment.

However, with the heat-resistant agent-containing resin particles obtained by this method, it has been found that the heat-resistant agent is easily dropped off by air blow after drying, and furthermore is easily oxidized and deteriorated during drying.

Therefore, the present invention solves this problem, and obtains polyamide resin particles in which the heat-resistant agent is hardly dropped off even during blowing, and the deterioration due to the external atmosphere during drying or solid-phase polymerization is largely suppressed. It is the main purpose.

[0010]

Means for Solving the Problems The present inventors have disclosed in Japanese Patent Application Laid-Open
As a result of further intensive studies on the method of JP-A-256649, when an aging treatment is performed after adding and mixing a heat-resistant agent in a solution state to polyamide resin particles, penetration of the heat-resistant agent is promoted, and the heat-resistant agent is hardly dropped off. Furthermore, the obtained heat-resistant agent-containing polyamide particles have a high concentration of the heat-resistant agent near the surface of the polyamide, and the concentration of the heat-resistant agent tends to decrease toward the inside of the particles. Even when the atmosphere at the time is poor, for example, even when the oxygen concentration at that time is high, it is found that the oxidative deterioration of the polyamide is suppressed, and it is possible to obtain polyamide resin particles of stable quality and an article made thereof, and thus the present invention. Reached.

That is, the above object of the present invention can be achieved by providing heat-resistant agent-containing polyamide resin particles in which the concentration of the heat-resistant agent is substantially reduced from the surface to the inside of the polyamide resin particles.

The heat-resistant agent-containing polyamide resin particles can be produced by adding and mixing the heat-resistant agent in a solution state to the polyamide resin particles, and then subjecting the mixture to an aging treatment.

Hereinafter, the present invention will be described in detail.

As the polyamide which can be used in the present invention, any known polyamide such as nylon 6, nylon 66, etc. may be used. The particles may have any shape, but pellets or chips are preferably used from the viewpoint of ease of handling. Further, a polyamide obtained by polymerizing a diamine and a dicarboxylic acid and / or a lactam may be used as it is, or an adsorbed water-containing polyamide extracted with hot water and then dehydrated may be used.

The heat-resistant agent which can be used by adding to the polyamide in the method of the present invention may be any of the above-mentioned organic and inorganic materials as long as it can be handled as a solution. A copper compound having a very large effect as the above is preferably used. For example, the copper compound that can be used in the present invention may be any compound as long as it is soluble in a solvent, but when water is selected as the solvent in consideration of economy, safety, handling, and the like. , Cupric chloride, ammonium cupric chloride, cupric bromide, copper nitrate, copper sulfate, cupric acetate, copper formate and the like. Of these, copper halide and copper acetate are preferred.

It is preferable to use the copper compound and an inorganic halide in combination. When water is similarly selected as the solvent in this combination, alkali metal or ammonium halides such as sodium iodide, potassium iodide, potassium bromide, sodium bromide, ammonium bromide, and ammonium chloride can be mentioned. Of these, potassium halide is preferred. In addition, it is a preferable method to use a copper halide-inorganic halide mixed aqueous solution when water is used as a solvent by utilizing the property that copper halide dissolves well in a concentrated inorganic halide solution.

The amount of the heat-resistant agent to be added to the polyamide is not particularly limited, except that it is required in a product in a subsequent step. Further, in the method of the present invention, it is essential that a heat-resistant agent is made into a solution, but the amount of the solvent added to these heat-resistant agents is not particularly limited.

The heat-resistant agent solution thus obtained is added to the polyamide particles and mixed. In this mixing process, the heat-resistant agent becomes uniform while adhering to the surface of the polyamide particles. As a method of adding and mixing, any method may be used.
The particles and the heat-resistant agent solution may be blended using an ordinary blender or the like, or may be blended at room temperature and pressure by a rotary dryer.

Next, in the method of the present invention, aging treatment is performed on the polyamide particles to which the heat-resistant agent solution is added and mixed. In this process, the heat-resistant agent penetrates from the surface of the polyamide particles together with the solvent into the inside, while a high-concentration heat-resistant agent is present on the surface, and a concentration distribution is formed in which the concentration decreases toward the inside. The aging treatment of the present invention means that the particles to which the heat-resistant agent solution has been added and mixed are allowed to stand for 2 hours or more without performing an operation such as heating or depressurizing that greatly changes the external atmosphere. There is no particular limitation on the external atmosphere as long as the solvent is retained in the polyamide without volatilization during the aging process.
The time of the aging treatment varies depending on the type of solvent used and the permeation rate to the polyamide. For example, when water is used as the solvent and at normal temperature and normal pressure, the aging time is preferably 2 hours or more. Is complete and preferred.

When the drying treatment is immediately performed while the aging treatment is inadequate, most of the unpermeated heat-resistant agent precipitates on the surface of the polyamide particles to form coarse particles, and if there is external oxygen, the oxidative deterioration reaches the inside of the polyamide. Not only that, the heat-resistant agent tends to fall off in a later step, which is not suitable. Also,
Since the fluidity of the particles is deteriorated due to the surface solution, handling problems such as blocking during transportation and difficulty in removing the particles from the container also occur.

The form of the concentration distribution of the heat-resistant agent in the polyamide resin particles of the present invention may be any as long as the concentration of the heat-resistant agent is higher on the particle surface than on the inside. When particles of the order of magnitude are used, the concentration of the heat-resistant agent at a depth of about several μm from the surface is reduced to the concentration inside the particles (at a depth of about several tens μm to several hundred μm from the surface). Those having about twice or more compared to those used are preferably used.

The polyamide resin particles of the present invention thus obtained have a high concentration of heat-resistant agent near the surface and are compatible with polyamide to a state close to the molecular level in the adsorption / penetration process. Even when oxygen is present at a high concentration during drying treatment such as phase polymerization, oxidative deterioration is suppressed from reaching the inside of the polyamide, and therefore, the next-step article (eg, fiber, resin molded product, etc.) made by melting the polyamide particles ) Can be stable and of good quality. On the other hand, in the conventional powder mixing method, since the heat-resistant agent is only physically attached to the polyamide surface only, it is easily oxidized, and the quality of the article in the next step tends to be inferior.

Further, compared with the case where a heat-resistant agent is added during polymerization, the heat-resistant agent hardly undergoes thermal deterioration due to heat history during polymerization, so that the quality and operability of the next step are good, and the heat-resistant agent is sufficiently adsorbed. / Because it has penetrated, there is almost no dropout of the heat-resistant agent even when transported by air.

[0024]

The present invention will be described in more detail with reference to the following examples. The properties such as physical properties in the following examples were evaluated as follows.

(A) Relative viscosity 2.5 g of a sample was dissolved in 25 ml of 98% sulfuric acid,
It measured at 25 degreeC using the Ostwald type viscometer.

(B) Concentration distribution of Cu and K atoms in particles 5 to 15% by using a secondary ion mass spectrometer (SIMS).
A keV energy ion beam is applied to the sample surface,
Secondary ions generated during sputtering were subjected to mass spectrometry to measure the concentration distribution.

(C) Absorbance (UVA) The sample was dissolved in 2: 1 sulfuric acid, and the absorbance at 292 nm (absorption wavelength of oxidized and degraded nylon) was measured.

(D) Residual rate of Cu and K The particles are pneumatically transported through a stainless steel pipe, passed through a polymer powder separator, and the ratio of the Cu and K amounts after transport to the Cu and K amounts before transport is determined in atomic percent. The evaluation was performed using an absorption method.

(E) Thread strength and elongation Using a Tensilon UTL-4L type tensile tester (manufactured by Orientec Co., Ltd.), JIS L-1017,
Measured according to 7.5.

(F) Number of foreign substances in the yarn The number of foreign substances in the filament of 180 mm was measured under an optical microscope. However, the size of the foreign matter is in the length direction of the filament, the foreign matter having a length of 1/10 or more of the diameter of the filament, and / or in the diameter direction of the filament,
Only the foreign matter having a length of 1/25 or more of the diameter of the filament was counted and converted into the number per 1.0 mg.

(G) Black light color tone The cheese on which the yarn was wound was placed under black light and visually inspected for fluorescence. When there is a substance having a fluorescence coloring tendency, such as a degraded substance, the substance has a white color.

(H) Content of Cu and K in Yarn After adding concentrated sulfuric acid and perchloric acid to the sample, the sample was heated and wet-decomposed, the decomposed liquid was diluted, and atomic absorption analysis was performed.

Example 1 An 80% aqueous solution of hexamethylenediammonium adipate was charged into a polymerization vessel and heated at 300 ° C.
For 2 hours to carry out polymerization. The obtained polymer was pelletized to obtain a nylon 66 pellet having a relative viscosity of 2.70, a diameter of 2.5 mm, and a length of 4.0 mm (pellet A).

The obtained pellets are charged into a blender,
5% by weight cupric acetate monohydrate aqueous solution (60 pp in terms of copper)
m, relative to polymer) and a 50% by weight aqueous solution of potassium iodide (350 ppm in terms of potassium, relative to polymer) were added, and the mixture was mixed at room temperature under normal pressure for 2 minutes. Next, the pellets were sealed in a stainless steel container at room temperature for 3 hours and left to stand for aging.

The concentration distribution of Cu and K atoms from the pellet surface to the inside in the diameter direction of the pellet was measured, and the results shown in FIG. 1 were obtained. The concentrations of Cu and K were highest near the pellet surface, and gradually decreased toward the inside.

Next, the pellet was heated at 160 ° C. and an oxygen concentration of 2
The mixture was allowed to stand under a nitrogen stream of 00 ppm and subjected to solid-state polymerization for 12 hours to obtain nylon 66 pellets having a relative viscosity of 3.60.

The results shown in Table 1 were obtained for the residual ratio of UVA and Cu and K in the pellets.

Next, the pellets were dried at a moisture content of 0.1% by weight.
Then, the polymer was melted to a polymer temperature of 290 ° C. using an extruder type spinning machine, and spun from a 0.3 mmφ die hole. The spun yarn was quenched by passing through a Uniflow chimney, a low-viscosity mineral oil was applied thereto, and hot-drawn.

The relative viscosity, strength, elongation,
The results shown in Table 1 were obtained for the black light color tone, the number of foreign substances in the yarn, and the stretchability (number of single yarn breaks).

Example 2 A pellet A obtained in Example 1 was charged into a blender in the same manner as in Example 1, and a copper iodide-potassium iodide aqueous solution in which copper iodide was dissolved in a 50% by weight aqueous potassium iodide solution. (60 ppm in terms of copper, 350 ppm in terms of potassium, relative to the polymer) and mixed at room temperature under normal pressure for 3 minutes. Next, the pellets were sealed in a stainless steel container at room temperature for 2 hours and left to stand for aging.

The concentration distribution of Cu and K atoms from the pellet surface to the inside in the diameter direction of the pellet was measured, and the results shown in FIG. 1 were obtained.

The pellets were weighed in a nitrogen stream having an oxygen concentration of 200 ppm in the same manner as in Example 1, and had a relative viscosity of 3.61.
Nylon 66 pellets were obtained.

Next, the operation and evaluation were performed in the same manner as in Example 1.
The characteristic values shown in Table 1 were obtained.

Comparative Example 1 The pellet A obtained in Example 1 was charged into a blender in the same manner as in Example 1, and copper iodide powder and potassium iodide powder (60 ppm in terms of copper, 350 ppm in terms of potassium, Polymer) was added thereto, and the mixture was mixed at room temperature and normal pressure for 20 minutes, and then allowed to stand in a closed container at room temperature and normal pressure for 3 days.

The concentration distribution of Cu and K atoms from the pellet surface to the inside in the diameter direction of the pellet was measured, and the results shown in FIG. 1 were obtained. Since Cu and K atoms were not detected from inside the pellet, it was confirmed that the heat-resistant agent was physically attached only to the pellet surface.

The pellets were weighed in a nitrogen stream having an oxygen concentration of 200 ppm in the same manner as in Example 1, and had a relative viscosity of 3.60.
Nylon 66 pellets were obtained.

Next, the operation and evaluation were performed in the same manner as in Example 1.
The characteristic values shown in Table 1 were obtained. Compared with Example 1 and Example 2 of the present invention, the value of UVA is large, the black light color tone is also white, and it can be seen that oxidation deterioration is progressing. In addition, the number of foreign substances in the yarn was large due to the degraded product, and the strength and elongation characteristics and stretchability of the yarn were poor.

Comparative Example 2 An 80% aqueous solution of hexamethylenediammonium adipate was charged into a polymerization vessel, and copper acetate and potassium iodide (60 ppm in terms of copper, 350 ppm in terms of potassium, relative to the polymer) were added.
For 2 hours to carry out polymerization. The obtained polymer was pelletized to obtain nylon 66 pellets having a relative viscosity of 2.69, a diameter of 2.5 mm, and a length of 4.0 mm.

The concentration distribution of Cu and K atoms from the pellet surface to the inside in the diameter direction of the pellet was measured, and the results shown in FIG. 1 were obtained. Since a heat resistant agent was added during the polymerization, the concentration distribution was uniform.

The pellets were weighed in a nitrogen stream having an oxygen concentration of 200 ppm in the same manner as in Example 1, and had a relative viscosity of 3.58.
Nylon 66 pellets were obtained.

Next, the operation and evaluation were performed in the same manner as in Example 1.
The characteristic values shown in Table 1 were obtained. Compared with Example 1 and Example 2 of the present invention, the value of UVA was slightly larger, and the black light color tone was white. Further, the number of foreign substances in the yarn was large, and the strong elongation characteristics and stretchability of the yarn were not good.

[0052]

[Table 1]

[0053]

According to the present invention, a high-concentration heat-resistant agent is present near the surface of resin particles and is compatible with polyamide to a state close to the molecular level, so that oxygen is present at a high concentration during drying treatment such as solid-phase polymerization. Even in this case, it is difficult for the oxidative deterioration to reach the inside of the polyamide, and therefore, it is possible to obtain a stable and high-quality product of the next process made by melting the polyamide particles with high productivity. Therefore, the resin particles of the present invention are fibers,
It is useful for producing films, resin molded products and the like.

[Brief description of the drawings]

FIG. 1 is a diagram of a concentration distribution curve showing the concentration distribution of Cu and K atoms in a pellet (chip) in an example from the result of measurement from the chip surface to the inside.

[Explanation of symbols]

Cu: concentration distribution curve of Cu atoms, K: concentration distribution curve of K atoms

Claims (4)

(57) [Claims] 1. A heat-resistant agent is added to a polyamide resin particle in a solution state.
Aging treatment for 2 hours or more after adding and mixing
By applying a heat-resistant agent, the heat-resistant agent-containing port has a substantially reduced concentration of the heat-resistant agent from the surface to the inside of the resin particles.
A method for producing heat-resistant agent-containing polyamide resin particles , which comprises producing amide resin particles. 2. The process for producing heat-resistant agent-containing polyamide resin particles according to claim 1, wherein the heat-resistant agent is a copper compound and an inorganic halide. 3. The polyamide is nylon 66 or nylon 6.
The method for producing heat-resistant agent-containing polyamide resin particles according to claim 1, wherein: 4. The heat-resistant agent is copper halide and / or copper acetate.
And potassium halide
Item 3. A method for producing a heat-resistant agent-containing polyamide resin particle according to item 2.