JP2641788B2 - Method for producing polyamide resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polyamide resin which forms a low-order condensate from an aqueous solution of a monomer or a salt of a constituent unit and increases the degree of polymerization using a melt extruder. The present invention relates to a method for producing a polyamide resin suitable for a thin-walled molded product such as a connector or a coil bobbin used in a high-temperature atmosphere.

<Conventional technology> Polyamide has been widely used in the automotive field, electric and electronic fields, etc. due to its excellent properties as an engineering plastic, and is often used as a material for thin molded products such as connectors and coil bobbins. Have been done.

Conventionally, nylon 6 and nylon 66 reinforced with glass fiber have been used for these molded products (Japanese Patent Laid-Open No. 59-1414).
61) With the recent rise in temperature in automobile engine compartments and the development of microelectronics due to technological innovation, there has been a demand for ultra-thin molded products that can withstand use in even higher temperatures. 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-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-62-15613
0). 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 (Japanese Patent Application Laid-Open No. 62-20527).

<Problems to be Solved by the Invention> However, these terephthalic acid and isophthalic acid-containing copolyamide resin compositions have a high melt viscosity when the number of terephthalic acid component units increases, and cannot be discharged by a normal melt polymerization method, Since the melting point of the polymer was close to the thermal decomposition temperature of the polymer, decomposition or degradation occurred during melt polymerization. Further, the method of performing a polymerization reaction in a solid state from a nylon salt to a polymer has a problem that the composition of the polymer is not stable.

<Means for Solving the Problems> In view of the above situation, the present inventors have inexpensive and highly fluid polyamide resin having high rigidity and high heat deformation temperature enough to withstand use in a high temperature atmosphere. As a result of intensive studies on the method of producing the composition, a [NH ₂ ] -rich low-order condensate was produced, and when the degree of polymerization was increased by a melt extruder, the dicarboxylic acid component was added to ensure efficient and stable high polymerization. The present inventors have found that a modified polymer is obtained and arrived at the present invention. That is, the present invention provides (1) a repeating unit A hexamethylene terephthalamide unit represented by any of the following repeating units (II) to (IV): A hexamethylene isophthalamide unit represented by A hexamethylene adipamide unit represented by And a copolymerization ratio of (I) / (II) = 55/4 by weight.
In producing a crystalline copolyamide having a range of 5 to 80/20 or (I) / (III) = 20/80 to 80/20 or (I) / (IV) = 55/45 to 90/10, 0.3 to 10 mol% based on the total number of moles of the monomers or salts of (I) to (IV)
Of diamine component in excess, 150-300 ° C, 10-20
Under a condition of kg / cm ² -G, a [NH ₂ ] -rich low-order condensate satisfying a relative viscosity (ηr) of a 1% sulfuric acid solution at 25 ° C. satisfying 1.01 to 1.6 is formed. A method for producing a polyamide resin, comprising adding a component and then increasing the degree of polymerization of the low-order condensate using a melt extruder.

The crystalline copolyamide of the present invention is any unit selected from (I) hexamethylene terephthalamide unit, (II) hexahemethylene isophthalamide unit, (III) hexamethylene adipamide unit and (IV) caproamide unit. A copolymerized polyamide formed from
(I) / (II) copolymerization ratio is 55/45 to 80/20 in polymerization ratio,
(Hereinafter referred to as 6T / 6I copolyamide) or (I) / (I
II) copolymerization ratio of 20/80 to 80/20 by weight (hereinafter 6T / 6
6 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.

According to the present invention, the copolymerization ratio of 6T / 6I is 55/45 to 80/2.
0, preferably 60 / 40-80 / 20, more preferably 60 / 40-70
Must be in the range of / 30. Further, the copolymerization ratio of 6T / 66 must be in the range of 20/80 to 80/20, preferably 35/65 to 70/30, more preferably 40/60 to 60/40. Further, the copolymerization ratio of 6T / 6 needs to be in the range of 55/45 to 90/10, preferably 60/40 to 85/15, more preferably 60/40 to 80/20. 6T / 6I, 6T / 66 and
The copolymerization ratio of 6T / 6 copolyamide is approximately
It relates to a crystalline copolyamide in the range 270 ° C to 340 ° C. When the copolymerization ratio of 6T / 6I, 6T / 66, and 6T / 6 is less than 40/60, 20/80, and 55/45, respectively, the polymer melting point decreases, and heat resistance such as heat distortion temperature decreases. It is not preferable. Also, when the copolymerization ratio of 6T / 6I, 6T / 66 and 6T / 6 is more than 80/20, 80/20, 90/10, respectively, the polymer melting point becomes higher and the heat resistance improves, but the processing temperature is higher. This is not preferable because the polymer causes thermal decomposition. The degree of polymerization of the crystalline copolyamide used here is not particularly limited, and a 1% sulfuric acid solution having a relative viscosity (ηr) at 25 ° C. of 1.5 to 5.0 can be arbitrarily used.

The low-order condensate produced under the conditions of 150 ° C. to 300 ° C. and 20 kg / cm ² -G or less according to the present invention refers to an aqueous solution of the above monomer or salt charged into a pressure polymerization vessel usually used for polymerization of nylon 66 or the like. Heat to 150-300 ° C under stirring conditions. The reaction temperature must be between 150 ° C and 300 ° C, preferably 180 ° C
280 ° C, more preferably 190 ° C to 270 ° C. If the reaction temperature is lower than 150 ° C., the reaction time becomes longer, which is not preferable.If 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 the time of producing the low-order condensate of the present invention 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.
20kg / cm ² -G, it is operated preferably so as to keep the 10~18kg / cm ² -G. The low-order condensate can be discharged from the polymerization vessel in a molten state at a temperature of 150 ° C. to 300 ° C. in order to give a remarkable freezing point drop due to the presence of a small amount of water.

The [NH ₂ ] -rich low-order condensate of the present invention means that in ordinary polyamide polymerization, the raw materials are charged so that the total amount of COOH groups and the total amount of NH ₂ groups contained in the monomers and salts are equal. However, in the present invention, the main objective is to make a large excess of the diamine component at the time of charging the raw materials and to positively produce a [NH ₂ ] -rich low-order condensate. Or 0.1 to the total number of moles of the dicarboxylic acid component unit and the diamine component unit of the salt.
It means that the diamine component is charged in an excess of 3 to 10 mol%. Here, the diamine component is an aliphatic alkylenediamine having 1 to 18 carbon atoms, and specific examples thereof include hexamethylenediamine, 1,8-diaminooctane, and 1,10-diaminodecane. Hexamethylenediamine, which is a component of the present polyamide, is preferred. The amount of the diamine component added is 0.3 to 10 mol%, preferably 0.5 to
It must be in the range of 8 mol%, more preferably 0.5 to 7 mol%. If the addition amount is less than 0.3 mol%, the conditions for increasing the degree of polymerization by melt extrusion become narrow, and stable operation becomes impossible. Also, 10 mol%
If it is larger than this, it is difficult to increase the degree of polymerization in a melt extruder, which is not preferable.

The relative viscosity (ηr) of the low-order condensate of the present invention is 1.01 to 1.6
And preferably in the range of 1.01 to 1.5, more preferably in the range of 1.01 to 1.4.
If the relative viscosity is lower than 1.01, the composition ratio may fluctuate in the melt-extrusion 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 discharge failure, or the low-order condensate precipitates out, which is not preferable.

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.

The method for increasing the degree of polymerization of the low-order condensate using a melt extruder according to the present invention is a method for increasing the degree of polymerization by melt-extruding the low-order condensate using a melt extruder. The melt extrusion temperature is preferably in the range of 10 to 30 ° C. higher than the melting point of the low-order condensate. When a low-order condensate having a high 6T content and a high melting point is used, the upper limit temperature must be 345 ° C. or lower in order to prevent thermal decomposition and thermal degradation of the polymer. As the melt extruder, a single screw or twin screw extruder can be used, but a twin screw extruder is preferable.

According to the present invention, a stable and highly polymerized polymer can be obtained very efficiently by adding a dicarboxylic acid component to a [NH ₂ ] -rich low-order condensate and performing melt extrusion. The dicarboxylic acid component is not particularly limited,
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 the dicarboxylic acid to be added is preferably in the range of the molar number corresponding to the excess [NH ₂ ] of the low-order condensate to [NH ₂ ] −20 × 10 ⁻⁵ mol / g. The amount of the dicarboxylic acid added may be larger than [NH ₂ ] of the low-order condensate, or [NH ₂ ] −20 × 10 ⁻⁵ mol / g
If the amount is less than this, it is not preferable because good high polymerization degree pellets cannot be obtained.

The method for adding the dicarboxylic acid to the low-order condensate of the present invention is not particularly limited, and any known method can be used. As a specific example of the addition method, a method of dry blending a dicarboxylic acid with a low-order condensate, or a method of separately supplying a low-order condensed portion and a dicarboxylic acid to an extruder using two auto feeders, and the like are simple. Suitable for.

Further, according to the present invention, the presence of a phosphorus-based catalyst is effective for obtaining good high polymerization degree pellets in the melt extrusion step, and the addition amount is preferably 0.02 to 2% by weight based on the low-order condensate. , More preferably 0.05 to 1.2 wt%. Specific examples of the phosphorus compound include H ₃ PO ₄ , H ₃ PO ₃ , H ₃ PO ₂ , H ₄ PO ₇ , and Na.
_{H 2 PO 4 · 2H 2 O} , Na 2 HPO 4 · 12H 2 O, Na 3 PO 4 · 12H 2 O, NaH 2 PO
_{4 · H 2 O, Na 4} P 2 O7 · 10H 2 O, Na 2 H 2 P 2 O 7 · 6H 2 O, Na 5 P
₃ O ₁₀ , C ₆ H ₅ P (OH) ₂ , C ₆ H ₅ PO (ONa) ₂ , C ₆ H ₅ PO (OH)
₂ , Mn (H ₂ PO ₂ ) ₂ , (C ₆ H ₅ O) ₃ P and the like. Preferably from _{H 3 PO 4, H 4 P} 2 O 7. There is no particular limitation on the method for adding the phosphorus compound, and a simple and suitable method is used when a low-order condensate is prepared, or a method in which the low-order condensate is preliminarily blended and melt-extruded.

It is preferable to add a filler to the polyamide resin obtained in the present invention. Fillers are glass fibers or beads, talc, kaolin, wollastonite, mica, silica, alumina, diatomaceous earth, clay, gypsum, redwood, graphite, titanium dioxide, zinc oxide, copper, stainless steel, and other powders. Or plate-like inorganic compounds, 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. Particularly preferred is a glass roving or glass chopped made of a continuous long fiber strand having a diameter of about 3 to 20 μm. Strands, glass threads and the like.
It is necessary that the compounding ratio of such a filler is 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 based on 100 parts by weight of the polyamide. It is. If the compounding ratio of the filler exceeds 200 parts by weight, the fluidity at the time of melting deteriorates, and not only it becomes difficult to injection-mold a thin-walled molded product, but also the appearance of the molded product is 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. As a specific example of the compounding method, dry-blending a filler into crystalline copolyamide pellets,
A method of melting and kneading with a single screw or twin screw extruder is used.

The crystalline copolyamide resin composition obtained by the present invention, when making a low-order condensate, melt extrusion high polymerization degree, such as a compound or molding step, if necessary, catalyst,
Heat stabilizers, weathering stabilizers, plasticizers, release agents, lubricants, nucleating agents, pigments, dyes, other polymers, and the like can be added.

<Example> Hereinafter, the present invention will be described in more detail with reference to examples.
Various properties in the examples and comparative examples were measured by the following methods.

1) Melting point (Tm) 8 to 10 mg of sample using DSC (PERKIN-ELMER7 type)
Is measured at a heating rate of 20 ° C./min, and the temperature at which the maximum value of the melting curve is obtained is defined as (T). Heat 8-10 mg of sample at a heating rate of 20 ° C./min and hold at T + 20 ° C. for 5 minutes, then
After cooling to 30 ° C. at a temperature lowering rate of 20 ° C./min, keeping the temperature at 30 ° C. for 5 minutes, it is heated again to T + 20 ° C. at a temperature increasing rate of 20 ° C./min. The maximum value of the melting curve at this time was taken as the melting point (Tm).

2) Terminal group concentration [NH ₂ ] of copolyamide 1 g of copolyamide was added to 100 ml of phenol / ethanol (5
(0/50 wt ratio) dissolved in a mixed solvent and titrated with a 1 / 50N aqueous hydrochloric acid solution.

3) Terminal concentration of copolyamide [COOH] 0.5 g of copolyamide was dissolved in 50 ml of hot benzyl alcohol and titrated with a 1 / 50N-KOH methanol solution.

4) Appearance of molded article The surface of the molded article was observed to be rough, bubbles, color tone, gloss, and the like.

：: glossy and smooth surface.

Δ: The gloss is reduced, but the surface is smooth.

X: The surface is rough without gloss.

5) Tensile strength Measured according to ASTM-D638.

6) Flexural strength Measured according to ASTM-D790.

7) Flexural modulus Measured according to ASTM-D790.

8) Izod impact strength Measured according to ASTM-D256.

9) Heat distortion temperature (HDT) Measured according to ASTM-D648, load 4.6 kgf / cm ² and load 18.6 kgf / cm ² .

<Example 1> Hexamethylene ammonium adipate (66 salt) 9.00
kg, terephthalic acid 6.47 kg, hexamethylene diamine 64.
8.41kg of 5wt% aqueous solution and 6.40kg of ion-exchanged water 0.05m ³
(5 mol% hexamethylene diamine is excessively charged with respect to the total number of moles of diamine component units and dicarboxylic acid component units), and after sufficient nitrogen replacement, a steam pressure of 17.5 kg / cm ^2. Heating was continued under -G pressure. After raising the temperature to 240 ° C over 3.5 hours with stirring, the reaction was maintained at 240 ° C to 245 ° C for 30 minutes 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 lower part of the polymerization vessel. The viscosity of this low-order condensate is ηr = 1.15, the melting point is 299 ° C., [COOH] = 52 × 10 ⁻⁵ mol / g, [NH ₂ ] = 105 × 10
^-5 mol / g, and was a low-order condensate rich in 53 × 10 ^-5 mol / g [NH ₂ ]. After vacuum drying the obtained low-order condensate at 100 ° C. for 24 hours, 43 g of terephthalic acid was dry-blended with respect to 1 kg of the low-order condensate, and the mixture was dried with a 30 mmφ vent-type twin-screw extruder.
Melt extrusion was performed at a temperature of 0 ° C to 335 ° C. Polymer viscosity η
White pellets with r = 2.90 and polymer melting point 300 ° C. were obtained. To 100 parts by weight of the pellets, 65 parts by weight of a glass fiber chopped strand having a length of 3 mm and a diameter of 13 μm were dry-blended and melt-mixed with a 30 mmφ single screw extruder at a temperature of polymer melting point + 20 ° C. This mixture was molded by an injection molding machine to prepare a test piece. Table 1 shows the results of evaluating the obtained test pieces.

<Example 2> Terephthalic acid 7.21kg, hexamethylene diamine 64.5w
t% aqueous 8.51kg, 3 mol% hexamethylene respect ε- caprolactam 5.25kg were charged deionized water 6.66kg batchwise pressurized polymerization kettle 0.05 m ³ (diamine total number of moles of component units and dicarboxylic acid component unit Methylene diamine is added in excess), and after sufficient nitrogen replacement, the steam pressure is reduced to 1
Heating was continued under a pressure of 5.0 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.
A low-order condensate was extracted at kg / cm ² -G. The melting point of the obtained low-order condensate is 302 ° C., ηr is 1.10, [COOH] = 114 × 10 ^−5.
mol / g, [NH ₂ ] = 143 × 10 ⁻⁵ mol / g, and 29 × 10 ⁻⁵ mo
It was a l / g [NH ₂ ] -rich low-order condensate. 24 kg of terephthalic acid was dry-blended with 1 kg of the low-order condensate, melt-extruded according to the method of Example 1, compounded and molded, and evaluated. The results are shown in Table 1.

<Example 3> terephthalic acid 6.70Kg, isophthalic acid 3.61Kg, were charged 64.5Wt% aqueous 12.26kg and ion-exchanged water 5.50kg of hexamethylenediamine batchwise pressurized polymerization kettle 0.05 m ³ (diamine component units and dicarboxylic 5 mol% hexamethylenediamine is overcharged with respect to the total number of moles of the acid component unit), and after sufficient nitrogen replacement, the steam pressure is 17.5 kg.
Heating was continued under a pressure of / cm ² -G. 230 under stirring for 5 hours
After the temperature was raised to 235 ° C., the temperature was maintained at 235 ° C. to 240 ° C. for 30 minutes to complete the reaction, and the differential pressure was 17.5 kg / cm ² − from the lower part of the polymerization vessel.
At G, the lower condensate was discharged into water. The viscosity of this low-order condensate was ηr = 1.15, and the melting point was 318 ° C. After vacuum drying the obtained low-order condensate at 100 ° C. for 24 hours, 43 g of terephthalic acid was dry-blended with respect to 1 kg of the low-order condensate, melt-extruded by the method of Example 1, compounded and molded, and evaluated. . The results are shown in Table 1.

<Examples 4 to 7> According to the method of Example 1, the raw material charge amount, terephthalic acid,
Table 1 shows the results of evaluation by changing the amount of the phosphorus-based catalyst and glass fiber added.

<Comparative Example 1> 5.89 kg of terephthalic acid, 10.00 kg of 66 salt, 6.37 kg of a 64.5 wt% aqueous solution of hexamethylenediamine, and 6.
A low-order condensate was prepared by the method of Example 1 using 36 kg.
The viscosity of this low-order condensate is ηr = 1.16, the melting point is 296 ° C., [C
OOH] = 78 × 10 ⁻⁵ mol / g, [NH ₂ ] = 69 × 10 ⁻⁵ mol / g, and a low-order condensate rich in 9 × 10 ⁻⁵ mol / g [COOH]. The resulting low-order condensate was vacuum-dried at 100 ° C. for 24 hours, and then melt-extruded at a temperature of 260 ° C. to 325 ° C. using a 30 mmφ vented twin-screw extruder. The foaming was remarkable and could not be pelletized.

<Comparative Example 2> 5.15 kg of terephthalic acid, 64.5 of hexamethylenediamine
5.58 kg of a wt% aqueous solution, 8.75 kg of ε-caprolactam and 5.50 kg of ion-exchanged water were charged into a 0.05 m ³ batch-type pressure polymerization vessel (3 mol% hexamole relative to the total number of moles of the diamine component unit and the dicarboxylic acid component unit). Methylenediamine was excessively charged), and a low-order condensate was prepared by the method of Example 1. The melting point of this low-order condensate is 250 ° C., ηr = 1.31, [COO
H] = 27 × 10 ⁻⁵ mol / g, [NH ₂ ] = 59 × 10 ⁻⁵ mol / g,
It was a low-order condensate rich in 32 × 10 ⁻⁵ mol / g [NH ₂ ]. This low-order condensate was vacuum-dried at 100 ° C. for 24 hours, and then dry-blended with 24 g of terephthalic acid per 100 parts by weight, and melt-extruded according to the method of Example 1. The melting point of the obtained pellet was 252 ° C. and ηr = 3.35.

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> 8.76 kg of terephthalic acid, 64.5 of hexamethylenediamine
wt% aqueous solution 10.15 g, 66 salt 2.63 kg and ion exchanged water 3.45
kg in a batch type pressure polymerization vessel of 0.05 m ³ (excessive addition of 3 mol% hexamethylene diamine to the total number of moles of diamine component units and dicarboxylic acid component units), and low-order condensation by the method of Example 1. I made things. The melting point of this low-order condensate was 343 ° C. and ηr = 1.07. This low-order condensate is vacuum-dried at 100 ° C. for 24 hours, and then dry-blended with 20 g of terephthalic acid for 100 parts by weight,
At a temperature of. Good pellets could not be obtained due to foaming due to thermal decomposition.

<Effect of the Invention> The crystalline copolyamide obtained by the present invention not only has high rigidity and heat deformation temperature, but also has good moldability. Therefore, thin-wall molding of connectors, coil bobbins, and the like used especially in a high-temperature atmosphere. Suitable as product material.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-283621 (JP, A) JP-B-48-36957 (JP, B1)

Claims (1)

(57) [Claims] 1. The repeating unit A hexamethylene terephthalamide unit represented by any of the following repeating units (II) to (IV): A hexamethylene isophthalamide unit represented by A hexamethylene adipamide unit represented by Wherein the copolymerization ratio is (I) / (II) = 55/4 by weight.
In producing a crystalline copolyamide having a range of 5 to 80/20 or (I) / (III) = 20/80 to 80/20 or (I) / (IV) = 55/45 to 90/10, 0.3 to 10 mol% based on the total number of moles of the monomers or salts of (I) to (IV)
Of diamine component in excess, 150-300 ° C, 10-20
Under the condition of kg / cm ² -G, a [NH ₂ ] -rich low-order condensate is prepared which satisfies the relative viscosity (ηr) of a 1% sulfuric acid solution at 25 ° C. satisfying 1.01 to 1.6. A method for producing a polyamide resin, comprising adding a component and then increasing the degree of polymerization of the low-order condensate using a melt extruder.