JP3106658B2 - Method for producing polyamide resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monomer having a constituent unit.
Also, the present invention relates to a method for producing a polyamide resin for producing a low-order condensate from an aqueous solution of a salt and increasing the degree of polymerization, and more particularly to a method for producing a polyamide resin suitable for automobile parts and electric / electronic parts.

[0002]

2. Description of the Related Art Polyamides have been widely used in the fields of automobiles, electric and electronic fields, etc., utilizing their excellent properties as engineering plastics.

Conventionally, these molded articles have been made of nylon 6 or nylon 66 reinforced with glass fiber (Japanese Patent Application Laid-Open No. 59-161461). With the development of microelectronics, there has been a demand for a material for an ultra-thin molded article that can withstand use in a high-temperature atmosphere. However, the melting points (Tm) of nylon 6 and nylon 66 are 220 ° C. and 260 ° C., respectively, and even when reinforced with glass fiber, the limit of the heat deformation temperature is only the melting point.

Recently, many copolyamide resin compositions containing terephthalic acid and isophthalic acid or glass fiber reinforced products thereof have been proposed as copolyamide resin compositions that can withstand use in such high-temperature atmospheres. JP-A-59-161428, JP-A-59-155426,
(JP-A-59-53536, JP-A-62-156130)
. As a production method, a method of performing a polymerization reaction in a solid state from a nylon salt to a polymer has been proposed (JP-A-62-20527).

[0005]

However, these terephthalic acid and isophthalic acid-containing copolyamide resin compositions have an increased melt viscosity when the terephthalic acid component unit is increased, and cannot be discharged by ordinary melt polymerization. Since the melting point of the polymer was close to the thermal decomposition temperature of the polymer, decomposition or degradation occurred during melt polymerization. In addition, a method of performing a polymerization reaction in a solid state from a nylon salt to a polymer is as follows.
There is a problem that the composition of the polymer is not stable.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, the present inventors have developed a polyamide resin having high rigidity and high heat deformation temperature which can sufficiently withstand use in a high-temperature atmosphere, and which are inexpensive and have good fluidity. As a result of intensive studies on a method for stably producing the composition, a low-order condensate having a large amount of terminal carboxyl groups is produced, and the low-order condensate is efficiently and stably increased by increasing the degree of polymerization. The inventors have found that a polymer is obtained, and have reached the present invention. That is, the present invention provides (1) a repeating unit (I) a hexamethylene terephthalamide unit represented by the following structural unit,

Embedded image And any of the following repeating units (II) to (IV): (II) a hexamethylene isophthalamide unit represented by the following structure:

Embedded image (III) a hexamethylene adipamide unit represented by the following structural unit,

Embedded image (IV) a caproamide unit represented by the following structural unit,

Embedded image And the copolymerization ratio is (I) / (II) = 55 by weight.
/ 45-80 / 20 or (I) / (III) = 20/8
0-80 / 20 or (I) / (IV) = 55 / 45-9
In producing the crystalline copolyamide in the range of 0/10, 0.3 to 1 with respect to the total number of moles of the monomers (I) to (IV) and the dicarboxylic acid component and the diamine component.
0 mol% of a dicarboxylic acid component is charged in excess,
~ 300 ° C, 1% under the condition of 20kg / cm ² -G or less
The relative viscosity (ηr) at 25 ° C. of the sulfuric acid solution is 1.01
A method for producing a polyamide resin, characterized in that a low-order condensate satisfying the conditions of 1.6 is satisfied, and then the degree of polymerization of the low-order condensate is increased.

The crystalline copolyamide of the present invention is selected from (I) hexamethylene terephthalamide unit, (II) hexamethylene isophthalamide unit, (III) hexamethylene adipamide unit and (IV) caproamide unit. And the copolymerization ratio of (I) / (II) is 55/4 by weight.
5 to 80/20 (hereinafter referred to as 6T / 6I copolyamide) or (I) / (III) having a copolymerization ratio of 2 by weight.
0/80 to 80/20 (hereinafter referred to as 6T / 66 copolyamide). Alternatively, it means that the copolymerization ratio of (I) / (IV) is in the range of 55/45 to 90/10 (hereinafter referred to as 6T / 6 copolyamide) by weight ratio.

According to the present invention, the copolymerization ratio of 6T / 6I is 55 / 45-80 / 20, preferably 60 / 40-8.
0/20, more preferably in the range of 60/40 to 70/30. Further, the copolymerization ratio of 6T / 66 is 20/80 to 80/20, preferably 35/65.
~ 70/30, more preferably 40/60 ~ 60/40
Must be in the range of The copolymerization ratio of 6T / 6 is 55/45 to 90/10, preferably 60/4.
0-85 / 15, more preferably 60 / 40-80 / 2
Must be in the range of 0. 6T / 6 here
The copolymerization ratios of I, 6T / 66 and 6T / 6 copolyamides are for crystalline copolyamides having a polymer melting point in the approximate range of 270 ° C to 340 ° C. 6T /
If the copolymerization ratio of 6I, 6T / 66, and 6T / 6 is less than 40/60, 20/80, and 55/45, respectively, the polymer melting point is lowered, so that heat resistance such as heat distortion temperature is lowered. Absent. Also, 6T / 6I, 6T
/ 66 and 6T / 6 have a copolymerization ratio of 80/2, respectively.
If it is more than 0, 80/20, or 90/10, the melting point of the polymer is increased and the heat resistance is improved, but the processing temperature is increased and the polymer is thermally decomposed. The degree of polymerization of the crystalline copolyamide is not particularly limited, and the relative viscosity (ηr) of a 1% sulfuric acid solution at 25 ° C. is usually 1.5 to 5.
What is in 0 can be used arbitrarily.

According to the present invention, 150 ° C. to 300 ° C., 20 kg /
A low-order condensate produced under a condition of not more than cm ² -G refers to a solution in which the above-mentioned monomer or salt is charged into a pressure polymerization vessel usually used for polymerization of nylon 66 or the like, and stirred under a stirring condition for 150 minutes.
Heat to <RTIgt; Reaction temperature is 150 ° C to 300
° C, preferably 180 ° C to 280 ° C,
More preferably, the temperature is 190 ° C to 270 ° C. When the reaction temperature is lower than 150 ° C., the reaction time becomes longer, which is not preferable. On the other hand, when the reaction temperature is higher than 300 ° C., the viscosity of the low-order condensate becomes too high, and it becomes difficult to discharge the low-order condensate. However, it is not preferable because a low-order condensate precipitates and discharge becomes impossible.

The pressure at which the low-order condensate of the present invention is formed means the equilibrium pressure of the mixture of the low-order condensate and water at that time, and the pressure increases as the internal temperature increases.
The system is 20 kg / cm ² -G or less, preferably 10 to 18
It is operated to keep it at kg / cm ² -G. The low-order condensate can be discharged from the polymerization vessel at a temperature of 150 ° C. to 300 ° C. in a molten state in order to give a remarkable freezing point drop due to the presence of a small amount of water.

The low-order condensate having a large amount of terminal carboxyl groups of the present invention refers to the total amount of total COOH groups and total NH contained in monomers and salts in ordinary polyamide polymerization.
_In general, the raw materials are charged so that the amounts of the _two groups are equal, but in the present invention, the dicarboxylic acid component is excessively added at the time of charging the raw materials, and a low-order condensate having a large amount of terminal carboxyl groups is positively produced. In particular, the dicarboxylic acid component is charged in an excess of 0.3 to 10 mol% with respect to the total number of moles of the constituent monomer and the total number of dicarboxylic acid component units and diamine component units of the salt. Means that.
Although there is no particular limitation on the excess dicarboxylic acid component,
Examples thereof include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. Preferred are isophthalic acid and terephthalic acid, and particularly preferred is terephthalic acid.
The amount of excess dicarboxylic acid added is from 0.3 to 10 mol%, preferably from 0.5 to 8 mol%, more preferably from 0.5 to 8 mol%.
It needs to be in the range of 7 mol%. The amount added is 0.
If the amount is less than 3 mol%, the condition for increasing the degree of polymerization becomes narrow, and stable operation becomes impossible, which is not preferable. Also, 10
If it is more than mol%, it is difficult to increase the degree of polymerization, which is not preferable. In order to facilitate the control of the degree of polymerization of the lower-order condensate and the degree of polymerization at a higher degree of polymerization, it is effective to add a degree of polymerization regulator. As the polymerization degree regulator, a monoamine compound or a monocarboxylic acid compound is usually used, but benzoic acid and stearic acid are preferable, and benzoic acid is particularly preferable. The polymerization degree regulator is used in an amount of 0 to 0.1 times, preferably 0.0001 to 0.05 times, the mole number of the constituent monomer and the total mole number of the dicarboxylic acid component unit and the diamine component unit of the salt. Used.

The low-order condensate of the present invention must have a relative viscosity (ηr) of 1.01 to 1.6, preferably 1.0 to 1.5, more preferably 1.01 to 1. .4. Relative viscosity (ηr) is 1.0
If the ratio is lower than 1, the composition ratio may fluctuate in the step of increasing the degree of polymerization, or the degree of polymerization may be insufficient, which is not preferable. On the other hand, if the relative viscosity is larger than 1.6, the melt viscosity of the low-order condensate becomes too high, causing ejection failure,
Or, a low-order condensate is undesirably precipitated because it causes ejection failure.

The apparatus for producing the low-order condensate of the present invention is not particularly limited, and a known apparatus such as a batch reactor or a 1 to 3 tank type continuous reactor can be used.

As a method for increasing the degree of polymerization of the low-order condensate of the present invention, a method using a melter, a method for solid-phase polymerization,
A method in which a melting machine and a solid-state polymerization machine are used together can be used. When a melting machine is used, the melting temperature is preferably in a range of 10 to 70 ° C. higher than the melting point of the low-order condensate. Also 6T
When a low-order condensate having a large content and a high melting point is used, the upper limit temperature must be 360 ° C. or lower in order to prevent thermal decomposition and thermal degradation of the polymer. As the melt extruder, an extruder, a needle
A twin screw extruder and a twin screw kneader are preferred.

The residence time in the melting machine is not particularly limited, but is preferably 1 minute or more, particularly preferably 2 minutes or more. If the residence time is short, it is not preferable because the degree of polymerization does not effectively increase. In order to increase the residence time and increase the degree of polymerization, it is effective to connect two or more melters in series. Although the presence of a phosphorus-based catalyst is effective for increasing the degree of polymerization, it is not preferable to add the catalyst because it has a disadvantage of impairing the heat resistance of the obtained polyamide resin.

The polymer having a high degree of polymerization can be further solid-phase polymerized, if necessary, to further increase the degree of polymerization.

As a method for solid-state polymerization of the low-order condensate of the present invention, a method of pressurizing or normal pressure in the presence of an inert gas,
Alternatively, a method of reducing the pressure or a combination thereof may be used. The solid-state polymerization temperature needs to be 150 ° C. to a melting point or less, preferably 200 ° C. to
Melting point -10C, more preferably 220C to melting point -15
° C. If the solid-state polymerization temperature is lower than 150 ° C., the reaction rate is undesirably slow. The solid-phase polymerization time is such that the relative viscosity (ηr) of the copolyamide used for ordinary molded products is 1.
Any time can be selected until it becomes 5-5. The solid-state polymerization apparatus of the present invention is not particularly limited, and any known method can be used. Specific examples of the solid phase polymerization apparatus include a kneader, a twin-screw paddle type, a tower type, a rotary drum type, and a double cone type solid state polymerization apparatus.

It is preferable to add a filler to the polyamide resin obtained in the present invention. Fillers include glass fibers or beads, talc, kaolin, wollastonite, mica, silica, alumina, diatomaceous earth, clay, gypsum, red iron, graphite, titanium dioxide, zinc oxide, copper, stainless steel, etc. And other polymer fibers (carbon fibers), etc., and preferably glass fibers. As the glass fiber, glass fiber is generally used as a reinforcing agent such as a thermoplastic resin or a thermosetting resin.
Glass rovings, glass chopped strands, glass threads, etc., made from strands of continuous long fibers of about 20 μm. The blending ratio of such a filler is
It is necessary that the amount be in the range of 0 to 200 parts by weight, preferably in the range of more than 0 to 150 parts by weight, particularly preferably 10 to 100 parts by weight. If the mixing ratio of the filler is more than 200 parts by weight, the fluidity at the time of melting becomes poor, and not only is it difficult to injection-mold a thin molded product, but also the appearance of the molded product is unfavorably deteriorated.

The method of blending the filler with the crystalline copolyamide of the present invention is not particularly limited, and any known method can be used. Specific examples of the compounding method include a method in which a filler is dry-blended into crystalline copolyamide pellets, and the mixture is melt-kneaded with a single-screw or twin-screw extruder. When the degree of polymerization is increased by a melter, a method of adding a filler in the middle of the melter is preferable because of high production efficiency.

The crystalline copolyamide resin composition obtained by the present invention may be prepared by adding a catalyst, a heat stabilizer, a weathering agent, etc., if necessary, to form a low-order condensate by melt extrusion, increasing the degree of polymerization, compounding or molding steps. Sex stabilizer, plasticizer, release agent,
Lubricants, nucleating agents, pigments, dyes, other polymers and the like can be added.

In order to improve the color tone of the polyamide resin, it is effective to add an antioxidant in an optional step such as during polymerization or at a higher degree of polymerization or during compounding. In particular, sodium hypophosphite and hindered phenol are effective. It is preferable to add a cellulose-based antioxidant.

[0022]

The present invention will be described in more detail with reference to the following examples. Various properties in the examples and comparative examples were measured by the following methods.

1) Melting point (Tm) Samples 8 to 10 were obtained using DSC (PERKIN-ELMER7 type).
The temperature which shows the maximum value of the melting curve obtained by measuring mg at a heating rate of 20 ° C./min is defined as (T). Sample 8 ~
10 mg is heated at a heating rate of 20 ° C./min and T + 20 ° C.
For 5 minutes, and then at a cooling rate of 20 ° C./min for 3 minutes.
After cooling to 0 ° C and holding at 30 ° C for 5 minutes,
Heat to T + 20 ° C. at a rate of ° C./min. The maximum value of the melting curve at this time was defined as the melting point (Tm).

2) Concentration of terminal group of copolyamide [NH ₂ ] 1 g of copolyamide was added to 100 ml of phenol / ethanol
(50 / 50wt ratio) mixed solvent, 1 / 50N
Was determined by titration with an aqueous hydrochloric acid solution.

3) Concentration of terminal group of copolyamide [COOH] 0.5 g of copolyamide was added to 50 ml of hot benzyl alcohol
In methanol, and titrated with a 1 / 50N-KOH methanol solution.

4) Tensile strength Measured according to ASTM-D638.

5) Flexural strength Measured according to ASTM-D790.

6) Flexural modulus Measured according to ASTM-D790.

7) Izod impact strength Measured according to ASTM-D256. 8) Heat deformation temperature (HDT) Measured according to ASTM-D648, a load of 4.6 kgf / cm ² and a load of 18.6 kgf / cm ² .

Example 1 Hexamethyleneammonium adipate (66 salt) 9.
00 kg, 6.72 kg of terephthalic acid, 7.02 kg of a 64.5 wt% aqueous solution of hexamethylenediamine, and 6.40 kg of ion-exchanged water were charged into a 0.10 m ³ batch-type pressure polymerization pot (diamine component unit and dicarboxylic acid component unit). 1 mol% terephthalic acid is excessively charged with respect to the total number of moles of
Heating was continued under a pressure of 7.5 kg / cm ² -G. After the temperature was raised to 240 ° C. over 3.5 hours with stirring, an additional 30 m
After maintaining the temperature at 240 ° C. to 245 ° C. during the reaction to complete the reaction, the low-order condensate was discharged into water at a differential pressure of 17.5 kg / cm ² -G from the bottom of the polymerization vessel. The viscosity of this low-order condensate is ηr
= 1.14, melting point 304 ° C., [COOH] = 113 × 10
^-5 mol / g, [NH ₂ ] = 88 × 10 ⁻⁵ mol / g, and a low-order condensate rich in 25 × 10 ⁻⁵ mol / g [COOH]. The obtained low-order condensate is treated at 100 ° C. for 24 hours.
After vacuum drying, the antioxidant Irganox 1098
(Antioxidant manufactured by Ciba-Geigy Co., Ltd.) was blended in an amount of 0.2 part by weight, and the residence time was 5 minutes in a vented twin-screw extruder of 30 mmφ,
At a maximum resin temperature of 320 ° C., the degree of polymerization was increased. White pellets having a polymer viscosity ηr = 2.70 and a polymer melting point of 302 ° C. were obtained. 3 mm length for 100 parts by weight of the pellet
× 6 glass fiber chopped strands with a diameter of 13 μm
The mixture was fed from the side feeder of the extruder so as to be 5 parts by weight and melt-mixed. This mixture was molded by an injection molding machine to produce a test piece. Table 1 shows the results of evaluating the obtained test pieces.

Example 2 8.76 kg of terephthalic acid, 8.93 kg of a 64.5 wt% aqueous solution of hexamethylenediamine, 6.00 kg of ε-caprolactam, and 6.66 kg of ion-exchanged water were added in 0.1 ml.
The mixture was charged into a 10 m ³ batch-type pressure polymerization reactor (2 mol% terephthalic acid was excessively charged with respect to the total number of moles of the monomer and dicarboxylic acid components and diamine component). Heating was continued under a pressure of 0.0 kg / cm ² -G. After the temperature was raised to 225 ° C. over 5 hours with stirring, the reaction was further allowed to proceed at 225 ° C. to 232 ° C. for 30 minutes.
The low-order condensate was extracted at 5.0 kg / cm ² -G. The melting point of the obtained low-order condensate is 303 ° C., ηr is 1.12,
[COOH] = 129 × 10 ⁻⁵ mol / g, [NH ₂ ] = 92
× 10 ⁻⁵ mol / g, and 37 × 10 ⁻⁵ mol / g.
[COOH] It was a rich low-order condensate. This low-order condensate was melted to a high degree of polymerization by the method of Example 1, compounded and molded, and evaluated. The results are shown in Table 1.

Example 3 8.12 kg of terephthalic acid, 4.12 k of isophthalic acid
g, 64.5 wt% aqueous solution of hexamethylene diamine 1
2.76 kg and 5.50 kg of ion-exchanged water are added in 0.1
The mixture was charged into a 0 m ³ batch-type pressure polymerization kettle (2 mol% terephthalic acid was excessively charged with respect to the total number of moles of diamine component units and dicarboxylic acid component units), and sufficiently purged with nitrogen. Heating was continued under a pressure of 5 kg / cm ² -G. After the temperature was raised to 230 ° C. over 5 hours with stirring, the temperature was further maintained at 235 ° C. to 240 ° C. for 30 minutes to complete the reaction, and the differential pressure was 17.5 k from the bottom of the polymerization vessel.
The low-order condensate was discharged into water at g / cm ² -G. The viscosity of this low-order condensate was ηr = 1.11 and the melting point was 317 ° C. The resulting low-order condensate was vacuum-dried at 100 ° C. for 24 hours, and then the degree of polymerization was increased by the method of Example 1 except for the conditions described in Table 1, followed by compounding and molding to evaluate. The results are shown in Table 1.

Examples 4 to 5 Table 1 shows the results of the evaluations conducted in accordance with the method of Example 1 while changing the raw material charge, the amounts of terephthalic acid and glass fiber added, and the like.

In each of the methods of Examples 1 to 5, a polyamide resin having a high degree of polymerization was obtained stably, and the molded article had excellent physical properties.

Comparative Example 1 6.48 kg of terephthalic acid, 9.00 kg of 66 salt, 7.02 k of a 64.5 wt% aqueous solution of hexamethylenediamine
g and ion-exchanged water 6.36 kg,
A low-order condensate was produced by the method described above. The viscosity of this low-order condensate is ηr = 1.20, the melting point is 301 ° C., [COOH] = 67 × 1
0 ^-5 mol / g and [NH ₂ ] = 66 × 10 ^-5 mol / g, which were low-order condensates having almost equal terminal group concentrations. The obtained low-order condensate was vacuum-dried at 100 ° C. for 24 hours, and then the degree of polymerization was increased by the method of Example 1. A fish with many fish eyes and a stable polymerization degree could not be obtained.

COMPARATIVE EXAMPLE 2 A batch-type pressure polymerization reactor of 6.68 kg of terephthalic acid, 6.38 kg of a 64.5 wt% aqueous solution of hexamethylenediamine, 10.00 kg of ε-caprolactam and 5.50 kg of ion-exchanged water was 0.10 m ^3. (3 mol% terephthalic acid was excessively charged with respect to the total number of moles of diamine component units and dicarboxylic acid component units), and a low-order condensate was produced by the method of Example 1. The melting point of this low-order condensate is 252 ° C., ηr = 1.33, [COOH] = 69 × 10 ⁻⁵
mol / g, [NH ₂ ] = 21 × 10 ⁻⁵ mol / g, and a low-order condensate rich in 48 × 10 ⁻⁵ mol / g [COOH]. This low-order condensate was vacuum-dried at 100 ° C. for 24 hours, and then was subjected to a high degree of melt polymerization according to the method of Example 1. The melting point of the obtained pellet is 253 ° C., ηr = 2.9.
It was 5.

Table 1 shows the results of evaluation using the pellets according to the method of Example 1. The stiffness and heat distortion temperature were low.

Comparative Example 3 1.19 kg of terephthalic acid, 1.21 kg of a 64.5 wt% aqueous solution of hexamethylene diamine, 0.10 k of 66 salt
g and 0.650 kg of ion-exchanged water to 0.005 m ³
(3 mol% terephthalic acid was excessively charged with respect to the total number of moles of the diamine component unit and the dicarboxylic acid component unit), and a low-order condensate was produced by the method of Example 1. The melting point of this low-order condensate is 361 ° C,
ηr = 1.05. After vacuum drying this low-order condensate at 100 ° C. for 24 hours, the degree of polymerization was increased at a maximum resin temperature of 375 ° C. Good pellets were not obtained because foaming due to thermal decomposition and fish eyes were mixed.

[0039]

[Table 1]

[0040]

The crystalline copolyamide obtained according to the present invention is not only high in rigidity and heat deformation temperature, but also has low water absorption and good moldability. Suitable as.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-283621 (JP, A) JP-A-60-163927 (JP, A) JP-A-2-145621 (JP, A) Patent 2641788 (JP, A) B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 69/00-69/50

Claims (1)

(57) [Claims] (1) a repeating unit (I) a hexamethylene terephthalamide unit represented by the following structural unit: And any one of the following repeating units (II) to (IV): (II) a hexamethylene isophthalamide unit represented by the following structural unit: (III) a hexamethylene adipamide unit represented by the following structural unit: (IV) a caproamide unit represented by the following structural unit: And the copolymerization ratio is (I) / (II) = 55 by weight.
/ 45-80 / 20 or (I) / (III) = 20/8
0-80 / 20 or (I) / (IV) = 55 / 45-9
In producing the crystalline copolyamide in the range of 0/10, 0.3 to 1 with respect to the total number of moles of the monomers (I) to (IV) and the dicarboxylic acid component and the diamine component.
0 mol% of a dicarboxylic acid component is charged in excess,
~ 300 ° C, 1% under the condition of 20kg / cm ² -G or less
The relative viscosity (ηr) at 25 ° C. of the sulfuric acid solution is 1.01
A method for producing a polyamide resin, which comprises producing a low-order condensate satisfying the conditions of 1.6 to 1.6, and then increasing the degree of polymerization of the low-order condensate.