JPH11172006A - Polyamide particulate matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous polyamide particulate matter suitable as a fiber- or resin material having a high rigidity at an elevated temperature, which has a high crystallizability and is commercialized through a minimal thermal history. SOLUTION: The total pore volume is from 0.10 to 0.30 cc/g, the size of a particulate matter expressed in terms of average length or average diameter is from 1 to 20 mm and the degree of crystallinity, calculated from the quantity of heat of fusion (ΔH) obtained by differential thermal analysis, is 50% or larger. Preferably, a polyamide is polyhexamethylene adipamide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to polyamide granules. More specifically, the present invention relates to a porous polyamide granular material suitable as a material for fibers and resins having excellent rigidity at high temperatures.

[0002]

2. Description of the Related Art Polyamide has been widely used as a material for fibers such as tire cords and a material for resins such as mechanical parts, electric parts and automobile parts because of its moldability and excellent mechanical properties. However, in recent years, the required characteristic level has become more severe for the purpose of replacing metals and the like, and particularly, improvement in rigidity at high temperatures is strongly desired.

Various methods have been proposed for improving the rigidity of polyamide at high temperatures.
As one of the methods, there is a method using a polyamide having a small amount of by-products obtained by solid-phase polymerization and having high crystallinity. For example, WO 94/21711 discloses a production method in which a diamine or a dicarboxylic acid is fed and polycondensation is carried out under substantially no atmospheric conditions under an inert gas environment under a condition that never takes a molten state. It is described that the polyamide obtained by the above has a high heat of fusion. See also Polymer, Vol. 26, 1582 (1
985), the polyamide obtained by solid-state polymerization is
It is disclosed to have a high melting point and heat of fusion.
The heat of fusion is generally used as an index of crystallinity, which means that the polyamide obtained by solid-state polymerization has high crystallinity. However, according to the study of the present inventors, in these conventional techniques, it is not always possible to obtain polycondensed polyamide granules in a solid state. ) And a plurality of melting steps such as a molding step, and it was found that the characteristics, that is, the high crystallinity disappeared. On the other hand, JP-A-4-27728 discloses that a diamine component is mixed with a dicarboxylic acid component and a catalytically effective phosphorus compound such as a metal hypophosphite in a solvent, and the solvent is removed. After forming a solid salt with the dicarboxylic acid, an inert gas is passed, and while removing generated water, polycondensation is performed at a temperature equal to or lower than the melting point of the salt to obtain a preliminary polycondensate. A method of condensing is disclosed. However, in this method, the molar balance between the diamine component and the dicarboxylic acid is very large, and a polyamide having a high molecular weight cannot be obtained. In Japanese Patent Application Laid-Open No. 7-90077, for example, a powder of polytetramethylene adipamide obtained by compressing polytetramethylene adipamide is used.
Although it is disclosed that pellets having a porosity of 1 to 20% by volume can be operated under mild conditions such as extrusion operation from solid pellets, there is no description about crystallinity or rigidity, and the present inventors have not disclosed. According to these studies, it has become clear that these conventional techniques cannot improve rigidity at high temperatures.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a product having high crystallinity and a minimum heat history,
It is an object of the present invention to provide a porous polyamide granular material having excellent rigidity at high temperatures and suitable as a material for fibers and resins.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the crystallinity calculated from the specific pore volume, granular material size, and heat of fusion is determined. It has been found that a product obtained by using the porous polyamide granules having high rigidity at high temperatures has been achieved.

That is, the present invention provides (1) (A) a total pore volume of 0.10 to 0.30 cc / g, and (B) a particle having an average length or an average diameter of 1 to 1.
And (C) a polyamide granule characterized by having a crystallinity of at least 50% calculated from the heat of fusion (ΔH) determined by differential thermal analysis. The polyamide granule according to the above (1), which is hexamethylene adipamide.

Hereinafter, the present invention will be described in detail. The polyamide in the present invention refers to an amide bond (-
NHCO-) means a polymer having, for example,
It is obtained by polycondensing a salt comprising a diamine component and a dicarboxylic acid component. As the diamine component, for example, tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,
2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine, p-xylylenediamine, 1,3-bis (aminemethyl) cyclohexane, 1,4- Bis (aminemethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5, -trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2, Examples include 2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethylpiperazine and the like.

The dicarboxylic acid component includes malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid,
Pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, suberic acid, dodecane diacid, eicodioic acid, terephthalic acid, isophthalic acid and the like can be mentioned.

The combination of the diamine and the dicarboxylic acid can be arbitrarily selected, and the component ratio of the diamine to the dicarboxylic acid (diamine / dicarboxylic acid) is 1.
A range of 3 to 0.9 is preferable, and a range of 1.2 to 0.95 is more preferable. In addition, a lactam such as ε-caprolactam, ζ-enantholactam, η-caprylactam, ω-laurolactam and the like may be added to the extent that the present invention is not impaired.

Further, a terminal blocking agent may be added for controlling the molecular weight or improving the hot water resistance. The terminal blocking agent is not particularly limited as long as it is a monofunctional compound having reactivity with a carboxyl group or an amino group at the polyamide terminal, but from the viewpoint of reactivity and stability of the blocking terminal,
Monoamines or monocarboxylic acids are preferred. Others
Acid anhydrides such as phthalic anhydride, monoisocyanates, monohalides, monoesters and monoalcohols can also be used.

The monoamine used as the terminal blocking agent is not particularly limited as long as it has reactivity with a carboxyl group. For example, methylamine, ethylamine, propylamine, butylamine, hexylamine,
Octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, aliphatic monoamines such as dibutylamine, cyclohexylamine, alicyclic monoamines such as dicyclohexylamine, aniline, toluidine, diphenylamine, aromatic monoamines such as naphthylamine, Alternatively, an arbitrary mixture thereof can be mentioned.

The monocarboxylic acid which can be used as a terminal blocking agent is not particularly limited as long as it has reactivity with an amino group. For example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid Acids, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, aliphatic monocarboxylic acids such as isobutylic acid, alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid, benzoic acid, toluic acid, α- Naphthalene carboxylic acid, β-naphthalene carboxylic acid, methyl naphthalene carboxylic acid, aromatic monocarboxylic acids such as phenylacetic acid,
Alternatively, an arbitrary mixture thereof can be mentioned.

In the polyamide of the present invention, polycondensation of a salt obtained from hexamethylenediamine as a diamine component and adipic acid as a dicarboxylic acid component is preferred, and 95 mol% or more of the number of repeating units in the molecular chain is hexamethylenediamine. Pamide is most preferred. The number of repeating units of hexamethylene adipamide in the molecular chain is 95
If it is less than mol%, the crystallinity tends to decrease significantly, and the rigidity at high temperatures tends to decrease.

The polyamide granules of the present invention have a total pore volume of 0.10 to 0.30 cc / g, preferably 0.13 to 0.30 cc / g.
0.27 cc / g, more preferably 0.15 to 0.2
5 cc / g. The total pore volume was measured using a mercury porosimeter (Model 1800, manufactured by Carlo Elba). A sample is taken in a dilatometer (sample tube), deaerated in a vacuum at room temperature with a mercury filling device, and measured with a mercury porosimeter in a range of pore radius of 3.5 nm to 5 μm to obtain all pores. The volume was determined. 0.1 total pore volume
Polyamide granules having a content of less than 0 cc / g cause problems such as a long moldability, for example, a long plasticizing time. In addition, polyamide granules having a total pore volume exceeding 0.30 cc / g are insufficient in strength, so that problems such as easy atomization during handling and voids in molded articles are liable to occur.

The polyamide granules of the present invention have a size with an average length or average diameter of 1 to 20 mm. The average length or average diameter is, for example, 100 to 1 arbitrarily selected.
The length or diameter of the 000 polyamide granules can be determined by measuring the length or diameter using a caliper, a micrometer, a microscope, or a projection, and calculating the number average.

The shape of the polyamide particles of the present invention can be arbitrarily selected, but is preferably cylindrical or spherical. In the case of a cylindrical shape, the average length is in the range of 1 to 20 mm, and the average diameter is in the range of 1 to 20 mm. In the case of a spherical shape, the average diameter is in the range of 1 to 20 mm. When the average length or the average diameter is less than 1 mm, problems such as adhesion to equipment occur when handling during molding, and when the average length or average diameter exceeds 20 mm, problems such as difficulty in handling and molding failure occur. .

The polyamide of the present invention has a heat of fusion (ΔH
The crystallinity calculated from (j / g)) is 50% or more, preferably 55% or more. . The heat of fusion is JIS K
In accordance with 7122, for example, it can be determined by the area of a melting curve obtained by a differential thermal analysis method (hereinafter, referred to as DSC) using 5 to 15 mg of a polyamide at a heating rate of 20 ° C./min. Further, the calculation of the degree of crystallinity from the heat of fusion is determined by the value of the heat of fusion of a complete crystal of the polyamide, for example, J. Am. Pol
ym. Sci. , Polym. Phys. Ed. , Vo
l. 22, 1651 (1984), etc.
It can be calculated by dividing by 90 (j / g). When the crystallinity calculated from the heat of fusion is less than 50%, the rigidity at high temperatures is not sufficient.

The polyamide of the present invention has a number average molecular weight of preferably 10,000 or more, preferably 1250 or more.
0 or more is more preferable. The molecular weight of the polyamide can be analyzed by gel permeation chromatography (GPC). For example, hexafluoroisopropanol (HFIP) is used as a solvent, and the sample concentration is 0.5-1.
Under the condition of 0 mg / ml, the obtained elution curve is converted into a molecular weight distribution curve in terms of polymethyl methacrylate (PMMA), and the number average molecular weight can be determined. When the number average molecular weight is less than 10,000, the melt viscosity at the time of molding is low, making molding difficult, and at the same time, properties, particularly toughness, tend to decrease. When the number average molecular weight is less than 10,000, the melt viscosity at the time of molding is low, making molding difficult, and at the same time, properties, particularly toughness, tend to decrease.

As a method for obtaining the polyamide granular material of the present invention, for example, a fine solid salt composed of a diamine and a dicarboxylic acid is obtained, and then a porous solid salt is prepared from the fine solid salt. A method in which polycondensation is always performed in a solid state using a solid salt, or a method in which a fine-grained solid salt composed of diamine and dicarboxylic acid is always pre-polycondensed in a solid state, and the obtained pre-polycondensation polyamide is finely divided by spray drying or pulverization. As a pre-polycondensation polyamide, and after the particulate pre-polycondensation polyamide as a porous pre-polycondensation polyamide,
A method in which polycondensation is performed in a solid state to a target molecular weight is exemplified, but a method in which polycondensation is always performed in a solid state using a porous solid salt composed of a diamine and a dicarboxylic acid is more preferable.

As a method for obtaining a fine solid salt, for example, water having a boiling point of 50 to 180 ° C., alcohols,
A method of dissolving or suspending the mixture in a solvent such as a ketone such as acetone or butanone or the like is exemplified.However, preferably, a dicarboxylic acid and a diamine are added to water to adjust pH as an aqueous solution. After making an aqueous solution containing a neutralized salt by, for example, a method of cooling or concentrating to precipitate a solid salt, a method of adding the aqueous solution in a poor solvent to precipitate at once, a method of spray drying the aqueous solution, and the like, From this aqueous solution, a fine solid salt can be obtained. The size of the obtained finely divided solid salt is 1 to 650 μm
Is more preferable, and the range of 10 to 500 μm is more preferable.

In order to increase the rate of polycondensation and to prevent deterioration during polymerization, a phosphorus compound can be added to the finely divided solid salt. As the phosphorus compound, for example, phosphoric acid, hypophosphorous acid, phosphorous acid, orthophosphorous acid, pyrophosphorous acid, phosphinic acids such as phenylphosphine, phosphonic acids such as phenylphosphonic acid, 2-methoxyphenylphosphonic acid, Examples thereof include 2- (2'-pyridyl) ethylphosphonic acid, and metal salts and partially neutralized salts thereof. As the metal of the metal salt, potassium, sodium, calcium, magnesium, aluminum, vanadium,
Manganese, zinc, lead, nickel, cobalt, ammonium and the like are exemplified. Further, phosphate esters, polymetaphosphoric acids, polyphosphoric acids, phosphine oxides, phosphonium halides and the like are also exemplified.

Further, an antioxidant, a heat stabilizer, a lubricant, a mold release agent, a fine solid salt are added to such an extent that the object of the present invention is not impaired.
Conventional additives such as a flame retardant, a crystal nucleating agent, a fibrous filler, and an antistatic agent can be added. As a method for adding, a known method can be used, but a method using a Henschel mixer is preferable.

A method for obtaining a porous solid salt from a finely divided solid salt is described in, for example, Perry's Chemical Engineers Handbook, 4th Edition (Perry's Chemical).
Engineere 'Handbook, 4th.
Edition, Mc. gra. H. II. New
York,) 8-62 / 61 (1963) (1), a method in which the solid salt is not melted can be adopted. Among them, a solvent is contained in the fine solid salt,
It is preferable to use a Henschel mixer or the like, mix well, granulate the finely divided solid salt with a rotary press granulator, and obtain a porous solid salt.

As the solvent to be contained in the finely divided solid salt,
Solvents having a boiling point of 50 to 180 ° C., for example, water, alcohols, mixtures thereof, and ketones such as acetone and butanone are exemplified. Among these solvents, it is most preferable to use water from the viewpoint of economy and stability. If the content of the solvent is too small, the yield of the porous solid salt is greatly reduced, and if it is too large, the handling tends to be difficult.

Further, as a method for producing a porous pre-polycondensation polyamide from the particulate pre-polycondensation polyamide,
Polycondensation is always performed in the solid state to obtain a pre-polycondensation polyamide, which is then made into a fine-grained pre-polycondensation polyamide by spray drying, pulverization, or the like. And a method of obtaining a porous pre-polycondensation polyamide by pelletizing the fine-particle polyamide with a rotary press granulator.

As the solvent to be contained in the fine-grained preliminary polycondensation polyamide, as in the above-mentioned method for producing a porous solid salt,
Solvents having a boiling point of 50 to 180 ° C., for example, water, alcohols, mixtures thereof, and ketones such as acetone and butanone are exemplified. Further, to the fine granular pre-polycondensation polyamide, a phosphorus compound, an antioxidant, a heat stabilizer, a lubricant, a release agent, a flame retardant, a crystal nucleating agent, a fibrous filler, an antistatic, to the extent that the object of the present invention is not impaired. Ordinary additives such as agents can be added.

As a method for performing polycondensation of the obtained finely divided solid salt or porous solid salt in a solid state at all times, a finely divided solid salt, a porous solid salt, and a porous solid salt are produced in the presence of an inert gas. The method of performing polycondensation below the melting point of the polycondensate to be performed is exemplified. Preferably, when a porous solid salt is used as a starting material for polycondensation,
After obtaining a porous pre-polycondensation polyamide below the melting point of the porous solid salt, a method of continuing the polycondensation to a desired degree of polymerization below the melting point of the porous pre-polycondensation polyamide in the second step is exemplified. . Further, when a fine solid salt is used as a starting material, as a first step, a pre-polycondensation polyamide is obtained at a temperature not higher than the melting point of the fine solid salt, and then a porous pre-polycondensation polyamide is prepared by the method described above. And second
An example is a method in which polycondensation is continued at a stage below the melting point of the porous pre-polycondensation polyamide to a desired degree of polymerization.

Examples of the inert gas include superheated steam, nitrogen,
Examples thereof include carbon dioxide and a mixed gas thereof.
In the polycondensation step, the inert gas may be sealed in the reactor and used, or may be used while constantly flowing through the reactor. The sealing and distribution may be combined as necessary. When flowing an inert gas, the flow rate is 1/20 to 20 times the capacity of the reactor per minute.
Times, preferably 1/10 to 10 times, more preferably 1
/7.5-7.5 times.

The temperature in the first stage of the step of obtaining the preliminary polycondensation is preferably from 130 ° C. to 5 ° C. below the melting point of the fine solid salt or the porous solid salt. Also,
The pressure is preferably ² to 50 kg / cm ^{2 in} terms of gauge pressure. The temperature in the second stage polycondensation step is the first
It is preferable to carry out at a temperature higher than the temperature used in the step and lower than the melting point of the pre-polycondensation polyamide obtained in the first step. The pressure is preferably lower than the pressure used in the first step.

In the first and second steps,
The temperature and pressure may be changed in multiple stages within the above-mentioned condition range. As the polymerization apparatus for obtaining the target polyamide, a known apparatus can be employed.In particular, a decomposer capable of cooling and removing water generated under pressurized conditions is provided, and an inert gas heated from the bottom is provided. An autoclave type polymerization apparatus equipped with a stirring blade having a drawer at the bottom and a sink is preferred.

Now, the present invention will be described in further detail with reference to Examples.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The physical properties were evaluated by the following methods. (1) Total pore volume [cc / g] 0.5 g of a sample was weighed into a dilatometer (sample tube), degassed at room temperature, 5 × 10 ^-2 mmHg for 1 hour with a mercury filling device, and manufactured by Carlo Elba. The measurement was performed using a 1800 type mercury porosimeter with a pore radius in the range of 3.5 nm to 5 μm. (2) Average length and average diameter [mm] of the granules 200 pieces were arbitrarily selected from the samples, and the lengths and diameters were measured with a micrometer, and the number average value was calculated and obtained. (3) Number average molecular weight (Mn) and weight average molecular weight (M
w) Determined by gel permission chromatography (GPC). The apparatus is HLC-8020 manufactured by Tosoh Corporation, the detector is a differential refractometer (RI), the solvent is hexafluoroisopropanol (HFIP), and the column is TSKge manufactured by Tosoh Corporation.
Two 1-SuperHM-H and one H1000 were used. The solvent flow rate is 0.3 ml / min and the sample concentration is 0.5 mg / ml. The obtained elution curve was converted into a molecular weight distribution curve by polymethyl methacrylate conversion (PMMA), and the number average molecular weight and weight average molecular weight were calculated. (4) Melting point (° C.) and heat of fusion (ΔH) (j / g) The measurement was performed according to JIS K7121 and K7122. D
It was determined using SC (PERKIN-ELMER7 type). Using 8 mg of sample, heating rate 20 ° C / min
The melting point was determined from the peak temperature of the melting curve obtained under the above conditions, and the heat of fusion was determined from the area. (5) Flexural modulus and flexural strength at 80 ° C. (Kg
/ Cm ² ) Polyamide injection molding machine (PS40 manufactured by Nissei Plastics Industries, Ltd.)
A test piece was prepared using E). Molding was performed at a cylinder temperature of 280 ° C. and a mold temperature of 80 ° C., with a cycle of 17 seconds of injection and 20 seconds of cooling. The flexural modulus and flexural strength at 80 ° C. were measured in a thermostat controlled at 80 ° C. according to ASTM790. (6) Moisture content (% by weight) Using a moisture vaporizer (VA-06, manufactured by Mitsubishi Chemical Corporation), 0.7 g of a sample was measured and determined by coulometric titration (Karl Fischer method).

[0033]

Example 1 (Preparation of polyamide granular material) Step of Producing Fine Solid Salt 1500 g of distilled water was placed in a 5 liter vessel with stirring blades, heated to 60 ° C., and then heated to 2324 g (20.0 mol).
1) Hexamethylenediamine is charged. Then 292
3 g (20.0 mol) of adipic acid is added and neutralized. The temperature of the neutralized aqueous solution was lowered to 23 ° C., and left standing for one day and night to remove water, to obtain a white precipitate.
It dried at 60 degreeC for 60 hours, and obtained the fine granular solid salt. The water content of the obtained solid salt was 1.6% by weight. 2. Step of preparing porous solid salt 125 g of distilled water was added to 3000 g of the obtained fine solid salt, and the mixture was sufficiently mixed using a Henschel mixer. This solid salt was poured into a granulator (F5-11-17 manufactured by Fuji Paudal).
Using 5), roller rotation speed 130 rpm, rate 3
A cylindrical solid salt was prepared under the conditions of 0 kg / hr and a temperature of 150 ° C., dried at 80 ° C. for 60 hours in a nitrogen stream, and sieved with a sieve (pore size: 0.850 mm) to obtain the desired porous solid. Salt was obtained. The yield of the obtained porous solid salt was 98.7% by weight in terms of weight ratio. The total pore volume was 0.18 cc / g. The water content was 1.3% by weight, and the average diameter and average length were 2.8 mm and 8.2 mm, respectively. Melting point (Tm)
Was 207 ° C. 3. Polycondensation Step Into a 5-liter autoclave-type vessel equipped with stirring blades having a withdrawal section at the bottom, 2,000 g of a porous solid salt was charged, sealed, and sufficiently purged with nitrogen.
The pressure is increased to 0 kg / cm ² , and nitrogen is constantly flowed from the lower part of the autoclave at a flow rate of 4 liter / min while maintaining the pressure. The temperature of the flowing nitrogen and the inside of the autoclave was increased to 170 ° C., and the state was maintained for 3 hours. Continuously, the temperature in the reactor and the temperature of nitrogen were raised to 190 ° C. over 10 hours while maintaining the flow rate and pressure of nitrogen. The flowing nitrogen was stopped, the pressure was reduced to 5 kg / cm ² over 15 minutes, the temperature was raised to 240 ° C. over 2 hours, and the state was maintained for 4 hours. At this time, it was constantly adjusted to be about 5 kg / cm ² . The temperature was lowered to room temperature, and the polycondensate was extracted.
The water generated in the series of pressurizing and heating steps was removed by a decomposer. The withdrawal of the polycondensate was carried out smoothly, and the obtained polymer almost maintained the shape of a porous solid salt. Almost no deposit was found in the autoclave. (Properties of the obtained polyamide granules) The total pore volume is
0.17 cc / g and the average diameter and average length of the granules were 2.5 and 6.7 mm, respectively.
The measurement results of the number average and weight average molecular weights of GPC were 12,500 and 36200, respectively. The melting point (Tm) is 261 ° C. and the heat of fusion is 110 (j /
g), and the crystallinity was calculated to be 57.9 (%).
The molding was carried out smoothly, and the flexural modulus and the flexural strength at 80 ° C. of the obtained molded piece were 7950 and 370 (kg / cm ² ), respectively.

[0034]

Example 2 (Preparation of polyamide granular material) Step of Producing Fine Solid Salt A salt was prepared in the same manner as in Example 1. 2. Preliminary polycondensation step (first stage) After charging 2000 g of finely divided solid salt into a 5-liter autoclave-type vessel equipped with stirring blades, sealing and sufficiently replacing with nitrogen, pressurizing to a gauge pressure of 5 kg / cm ² , The inside of the autoclave was sealed. Raise the temperature to 190 ° C.
Hold that state for hours. The pressure rose to 15 kg / cm ² . Subsequently, it was cooled to normal pressure. The water generated in the series of pressurizing and heating steps was removed by a decomposer. Since the polycondensate was in a lump, the autoclave was decomposed and extracted. Thereafter, it was pulverized by a pulverizer until it became fine particles. This series of polymerization operations was performed twice. 3. Step of preparing porous pre-polycondensation polyamide 1 in 3000 g of the obtained particulate pre-polycondensation polyamide
25 g of distilled water was added and mixed well using a Henschel mixer. Using a granulator (F5-11-175 manufactured by Fuji Paudal Co.), this particulate pre-polycondensation polyamide was used at a roller rotation speed of 130 rpm and at a rate of 30 kg / h.
r and a temperature of 150 ° C., a cylindrical porous pre-polycondensation polyamide was prepared, and a sieve (pore size 0.850) was prepared.
mm). The yield of the obtained porous pre-polycondensation polyamide was 80.1% by weight in terms of weight ratio.
Met. The total pore volume was 0.27 cc / g. The water content was 2.3% by weight, and the average diameter and average length were 2.8 mm and 7.5 mm, respectively. Melting point (Tm) was 271 ° C. 4. Polycondensation Step (Second Step) The porous prepolycondensation polyamide is placed in a 5-liter autoclave-type container equipped with stirring blades having a withdrawal section at the bottom.
After 2,000 g had been charged and sealed, the atmosphere was sufficiently replaced with nitrogen, and then the gauge pressure was increased to 5 kg / cm ² , and the temperature was increased to 240 ° C.
After that, the temperature was maintained for 4 hours. At this time,
It was constantly adjusted to be about 5 kg / cm ² . The water generated in this series of steps was removed by a decompressor.
The temperature was lowered to room temperature, and the polycondensate was extracted. The sample was withdrawn smoothly, and the obtained polymer retained almost the shape of the porous pre-polycondensate. However, a small amount of finely powdered polymer was observed. (Properties of the obtained polyamide granules) The total pore volume is
0.26 cc / g, and the average diameter and average length are:
They were 2.5 and 6.0 mm, respectively. The measurement results of GPC number average and weight average molecular weight were 29
700 and 63700. In addition, melting point (Tm)
Was 279 ° C., the heat of fusion was 120 (j / g), and the crystallinity was calculated to be 63.2 (%). Molding is
The molding was performed without any problem, although the molded article tended to have voids. The flexural modulus and flexural strength at 80 ° C. of the obtained molded product were 7500 and 360, respectively.
(Kg / cm ² ).

[0035]

Example 3 (Preparation of polyamide granular material) Step of Producing Fine Solid Salt 1500 g of distilled water was placed in a 5 liter vessel with stirring blades, heated to 60 ° C., and then heated to 2324 g (20.0 mol).
1) Hexamethylenediamine is charged. Then 292
3 g (20.0 mol) of adipic acid is added and neutralized. 49.0 g of sodium hypophosphite monohydrate was further added to the neutralized aqueous solution, the temperature of the aqueous solution was lowered to 23 ° C., and the solution was left standing overnight to remove water, and a white precipitate was obtained. It was dried at 60 ° C. for 60 hours in a vacuum dryer. 2. Step of preparing porous solid salt 62.5 g of distilled water was added to 3000 g of the obtained fine solid salt, and the mixture was sufficiently mixed using a Henschel mixer.
This solid salt was added to a granulator (F5-11-1 manufactured by Fuji Paudal).
75), a cylindrical solid salt is prepared under the conditions of a roller rotation speed of 130 rpm, a rate of 30 kg / hr, and a temperature of 150 ° C., and is dried in a vacuum dryer at 60 ° C. for 60 hours. .850 mm) to obtain the desired porous solid salt. The yield of the obtained porous solid salt was 93.0% by weight in terms of weight ratio.
The total pore volume was 0.24 cc / g. The water content was 0.04% by weight, and the average diameter and average length were 2.8 mm and 5.3 mm, respectively. The melting point (Tm) was 208 ° C. 3. Polycondensation step 500 g of the porous solid salt was placed in a 5-liter autoclave-type vessel equipped with stirring blades having a withdrawal section at the bottom, sealed, and sufficiently purged with nitrogen.
/ Cm ² , and the inside of the autoclave was sealed. The temperature was raised to 190 ° C. and kept there for 3 hours. The pressure rose to 13.5 kg / cm ² . Continuously, the gauge pressure was reduced to 5 kg / cm ² ,
And kept that state for 4 hours. At this time,
It was adjusted to about 5 kg / cm ² . The water generated in the series of pressurizing and heating steps was removed by a decomposer. In the obtained polymer, a little lumps were observed, but almost the shape of the porous solid salt was maintained. In the following evaluation, lump-shaped materials were removed. (Properties of the obtained polyamide granules) The total pore volume is
0.14 cc / g, and the average diameter and average length are:
They were 2.5 and 5.0 mm, respectively. The measurement results of GPC number average and weight average molecular weight were 22
300 and 50200. In addition, melting point (Tm)
Was 270 ° C., the heat of fusion was 115 (j / g), and the crystallinity was calculated to be 60.5 (%). Molding was performed without any problem, although it took some time for plasticization. The flexural modulus and flexural strength at 80 ° C. of the obtained molded piece were 7550 and 360 (kg / cm ² ), respectively.

[0036]

Comparative Example 1 (Preparation of Polyamide Granules) Step of Producing Fine Solid Salt A salt was prepared in the same manner as in Example 1. 2. Preliminary polycondensation step (first stage) Into a 5 liter autoclave type vessel equipped with stirring blades, 2,000 g of fine solid particles were charged, and 2,000 g of pure water were further charged and stirred well. After sealing, the atmosphere was sufficiently replaced with nitrogen, and the temperature was increased to 220 ° C., and this state was maintained for 2 hours. At this time, the pressure of the autoclave is always about 18k.
The water produced to give g / cm ² was removed out of the system by means of a separator. Thereafter, the autoclave was cooled. Since the polycondensate was aggregated, the autoclave was decomposed and extracted. Then, it was pulverized by a pulverizer until it became fine particles. This polymerization operation was performed twice. 3. Step of Producing Porous Pre-polycondensation Polyamide This was carried out in the same manner as in Example 2. The yield of the obtained porous prepolycondensation polyamide was 82.1% by weight in terms of weight ratio. The total pore volume was 0.27 cc / g. Also,
The water content was 2.4% by weight, the average diameter and average length were 2.8 mm and 7.3 mm, respectively. 4. Polycondensation Step (Second Step) It was carried out in the same manner as in Example 2. (Properties of the obtained polyamide granules) The total pore volume is
0.24 cc / g, and the average diameter and average length are:
They were 2.5 and 6.2 mm, respectively. The measurement results of GPC number average and weight average molecular weight were 21
700 and 44200. In addition, melting point (Tm)
Is 267 ° C., the heat of fusion is 72 (j / g),
The crystallinity was calculated to be 37.9 (%). The molding was performed smoothly, and the flexural modulus and flexural strength at 80 ° C. of the obtained molded product were 6250 and 325, respectively.
(Kg / cm ² ).

[0037]

Comparative Example 2 (Preparation of Polyamide Granules) Step of Producing Fine Solid Salt 1500 g of distilled water was placed in a 5 liter vessel with stirring blades, heated to 60 ° C., and then heated to 2324 g (20.0 mol).
1) Hexamethylenediamine is charged. Then 292
3 g (20.0 mol) of adipic acid is added and neutralized. The temperature of the neutralized aqueous solution was lowered to 23 ° C., and left standing for one day and night to remove water, to obtain a white precipitate.
At 60 ° C. for 60 hours.
0 g of hexamethylenediamine was added and the mixture was stirred well with a Henschel to obtain a finely divided solid salt. 2. Polycondensation Step After charging 2000 g of finely divided solid salt into a 5 liter autoclave-type vessel equipped with stirring blades having a draw-out section at the bottom, tightly closing and sufficiently replacing with nitrogen, the nitrogen was constantly supplied from the lower part of the autoclave under atmospheric pressure. 4 liters /
Per minute, the flowing nitrogen and the temperature inside the autoclave were raised to 180 ° C., and the state was maintained for one hour. Subsequently, while continuously maintaining the flow rate of nitrogen, the temperature in the reactor and the temperature of nitrogen were raised to 240 ° C. over 4 hours, and then the state was maintained for 4 hours. The water generated in the series of pressurizing and heating steps was removed by a decomposer.
Since the polycondensate was in a lump, the autoclave was decomposed and extracted. Then, it was pulverized by a pulverizer to obtain a granular polyamide. 3. Extrusion process Small twin screw extruder (Laboplast Mill ME manufactured by Toyo Seiki Co., Ltd.)
Using a mold, pelletization was performed under the conditions of a cylinder temperature of 280 ° C., a screw rotation speed of 70 rpm, and a rate of 4 kg / hr. (Properties of the obtained polyamide granules) The total pore volume is
0.08 cc / g, and the average diameter and average length are:
They were 1.5 mm and 5.8 mm, respectively. GP
The measurement results of the number average and weight average molecular weights of C were 14,500 and 34500, respectively. The melting point (T
m) was 267 ° C., the heat of fusion was 80 (j / g), and the crystallinity was calculated to be 42.1 (%). Molding was extremely long plasticizing time and very difficult. The flexural modulus and flexural strength at 80 ° C. of the obtained molded product were 6300 and 330 (kg / cm ² ), respectively.

[0038]

Comparative Example 3 (Preparation of Granular Polyamide) Step of Producing Fine Solid Salt It was carried out in the same manner as in Comparative Example 2. 2. Polycondensation step was carried out in the same manner as in Comparative Example 2. The obtained massive polyamide was finely pulverized by a pulverizer. Using a sieve (pore size: 0.850 mm), only those that passed through the sieve were collected. (Properties of the obtained polyamide granules) The total pore volume is
0.15 cc / g and an average diameter of less than 1 mm. The measurement results of the number average and weight average molecular weights of GPC were 14,200 and 35,000, respectively. Also,
The melting point (Tm) is 260 ° C. and the heat of fusion is 113 (j
/ G), and the crystallinity was calculated to be 59.4 (%). When molding was attempted using a molding machine, adhesion to a hopper or the like was extremely large, and a molded product could not be obtained.

[0039]

Comparative Example 4 (Preparation of Polyamide Granules) Step of Producing Fine Solid Salt The procedure was the same as in Example 3. 2. Step of Producing Porous Solid Salt The obtained fine solid salt is converted into a granulator (F5 manufactured by Fuji Paudal).
-11-175), the roller rotation speed is 130 rpm
m, a rate of 30 kg / hr, and a temperature of 150 ° C. to prepare a cylindrical solid salt, which was prepared in a vacuum dryer at 60 ° C. for 6 hours.
After drying for 0 hour, the mixture was sieved with a sieve (pore size: 0.850 mm) to obtain the desired porous solid salt. The yield of the obtained porous solid salt was 35.0% by weight in terms of weight ratio.
Met. The total pore volume was 0.43 cc / g. The water content was 0.04% by weight, and the average diameter and average length were 2.8 mm and 5.3 mm, respectively. 3. Polycondensation step After carefully charging 2,000 g of the porous solid salt into a 5 liter autoclave-type container with stirring blades having a withdrawal section at the bottom, tightly closing, and sufficiently replacing with nitrogen, under atmospheric pressure,
Nitrogen was constantly flowed from the lower part of the autoclave at a flow rate of 4 liters / minute, the flowing nitrogen and the temperature inside the autoclave were raised to 160 ° C., and the state was maintained for 10 hours. Subsequently, the flow rate of nitrogen was continuously increased to 2 liters / minute, the temperature was increased to 170 ° C., and the state was maintained for 4 hours. Continuously, while maintaining the nitrogen flow rate, 180
The polycondensation was carried out under the conditions of 5 ° C. for 5 hours, 190 ° C. for 6 hours and 198 ° C. for 3 hours. The water generated in the series of pressurizing and heating steps was removed by a decomposer. The obtained polymer was divided into those retaining the shape of the porous solid salt and those that were atomized. (Properties of the obtained polyamide granules) The total pore volume is
It was 0.32 cc / g. The measurement results of the number average and weight average molecular weights of GPC were 6200 and 150, respectively.
00. The melting point (Tm) is 260 ° C.
The heat of fusion is 96 (j / g), and the crystallinity is 50.5.
(%). Molding was attempted, but adhesion to the hopper due to atomization was large, and a large amount of voids were generated in the molded product, and evaluation could not be performed.

[0040]

According to the present invention, (1) when commercialized, the extrusion step can be omitted, and it is industrially extremely effective. (2) A product having excellent rigidity at high temperatures can be obtained. (3) When various additives and fillers are added and blended, the resulting polyamide is porous, so that its addition efficiency is higher than in the past and extremely industrially effective.

Claims (2)

[Claims] (A) a total pore volume of 0.10 to 0.30
cc / g, and (B) the size of the granular material is 1 to 20 mm in average length or average diameter, and (C)
A polyamide granular material having a degree of crystallinity calculated from the heat of fusion (ΔH) determined by differential thermal analysis of 50% or more. 2. The polyamide granule according to claim 1, wherein the polyamide is polyhexamethylene adipamide.