JPS60163928A - Production of polyamide - Google Patents

Abstract

PURPOSE:To obtain a polyamide excellent in heat resistance, sliding property, etc., by polycondensing a hexamethylenediamine salt of an aromatic dicarboxylic acid component based on terephthalic acid or a lower condensate of this salt in a solid phase at a specified temperature. CONSTITUTION:An aromatic dicarboxylic acid component mixture of 60- 85mol% terephthalic acid component units and 40-15mol% aromatic dicarboxylic acid component units other than terephthalic acid units (e.g., isophthalic acid units) is reacted by heating with hexamethylenediamine to form a hexamethylenediamine salt of the aromatic dicarboxylic acids or a lower condensate of this salt. Said salt of condensate is polycondensed at a temperature ranging from the m.p. of the polycondensation reaction mixture -100 deg.C to the m.p. to obtain the purpose polyamide suitable as, for example, a molding material for sliding materials.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a molding material that has excellent performance in terms of heat resistance, mechanical properties, chemical and physical properties, and moldability, and a polyamide material that has excellent sliding properties. This relates to a manufacturing method.

In general, thermoplastic resins such as polyolefins, polyesters, and polyamides can be melt-molded such as compression molding, injection molding, or extrusion molding, and have excellent moldability, but have poor heat resistance, mechanical properties, and chemical properties. None of these properties are satisfactory as engineering plastics, and they are used in various general-purpose molding fields by taking advantage of their respective characteristics.

Conventionally, engineering plastics with excellent heat resistance, mechanical properties, and chemical and physical properties include polytetrafluoroethylene (Teflon), polyparaphenylene terephthalamide (Kevlar), 4,4'-diaminodiphenyl ether, and pyromelli. Polyimide (Kapton), polyhexamethyleneaziboamide (6,6-nylon), poly2,4.4-1-lymethylene terephthalamide (Trogamide), polyacetal, etc. It has been known. Among these, polytetrafluoroethylene, polyterephthaloyl paraphenylene diamine, and the above-mentioned polyimide resins have excellent heat resistance, mechanical properties, and chemical and physical properties, but they have the disadvantage that they cannot be melt-molded. However, its field of use is extremely limited. Among these engineering plastics, polyhexamethylene aziboamide (6,6-nylon), 2,4.4-trimethylhexamethylene terephthalamide (Trogamide T), and polyacetal are all meltable. Although they have the characteristic of being moldable, all of these polyamides have poor heat resistance properties such as glass transition temperature and heat distortion temperature.
Polyacetal has poor mechanical properties such as tensile properties, bending strength, limit PV value, abrasion resistance, and chemical and physical properties such as chemical resistance, boiling water resistance, and saturated water absorption, and polyacetal has poor heat resistance such as melting point and heat distortion temperature. They each have the disadvantage of being inferior in mechanical properties such as bending strength, impact strength, and abrasion resistance, and are particularly suitable for applications as molding materials for sliding materials that require heat resistance and have excellent sliding properties. Not yet.

The present inventors have developed a molding material for sliding materials that has excellent heat resistance properties, mechanical properties, chemical and physical properties, and moldability, and has particularly excellent sliding properties. As a result of investigation, it was found that a specific polyamide consisting of an aromatic dicarboxylic acid component unit and an alkylene diamine component unit whose main component is a terephthalic acid component skewer is excellent in the above-mentioned performance. However, conventionally, this polyamide has been mainly produced by a method of polycondensing a corresponding aromatic dicarboxylic acid cybaride and an alkylene diamine in the presence of a base, but in this method, the aromatic dicarboxylic acid cybaride is expensive, and the polyamide is could not be manufactured economically.

Another method is to polycondense an alkylene diamine salt of an aromatic dicarboxylic acid or a lower condensate thereof formed from a corresponding aromatic dicarboxylic acid component unit and an alkylene diamine component unit under melting conditions. Although this method is known and is industrially excellent, the polyamide produced by this method has poor mechanical strength, heat resistance, and color tone, and is therefore unsatisfactory for use in the above-mentioned applications.

The present inventors have developed an alkylene diamine salt of an aromatic dicarboxylic acid formed from an aromatic dicarboxylic acid component unit and an alkylene diamine component unit, or a lower-order condensate thereof, through a polycondensation reaction under solid-state conditions to achieve excellent performance. As a result of studying methods for producing polyamide, we found that an alkylene diamine salt of an aromatic dicarboxylic acid formed from an aromatic dicarboxylic acid component unit having a specific composition and an alkylene diamine component at the tI1 position or a lower condensate thereof under specific conditions. It has been discovered that the above object can be achieved by polycondensation with
We have arrived at the present invention. According to the present invention, the polyamide produced by the production method of the present invention has heat resistance properties such as melting point, glass transition point and heat distortion temperature, tensile strength, bending strength,
Impact strength, coefficient of dynamic friction, limits 1) Mechanical properties such as V value and taper wear, especially chemical and physical properties such as sliding properties, chemical resistance, boiling water resistance, saturated water absorption, and fluidity of molten compositions. It is characterized by excellent moldability such as melt compression moldability, melt injection moldability, and melt extrusion moldability.

Further, the method of the present invention is a manufacturing method that is superior in industrial implementation compared to conventional methods, and is characterized in that the polyamide can be manufactured at low cost.

To summarize the present invention, the present invention comprises an aromatic dicarboxylic acid component unit (a) and an alkylene diamine component unit (bl
In a method for producing a polyamide by heating and polycondensing an alkylene diamine salt or a lower condensate of an aromatic dicarboxylic acid formed from an aromatic dicarboxylic acid under solid state conditions, (i) the aromatic dicarboxylic acid component unit ta+ is Terephthalic acid component degree is 60 to 85 mol% and aromatic dicarboxylic acid component units other than terephthalic acid are 15 to 40
and (ii) the polycondensation reaction is conducted under conditions that maintain a solid phase state, and (ii) the polycondensation reaction is carried out under conditions that maintain a solid phase state. The gist of the present invention is a method for producing a polyamide, characterized in that the temperature at that time is 100° C. lower than the melting point of the polycondensation reaction mixture of the polycondensation system or below the melting point.

In the method of the present invention, the alkylene diamine salt or lower condensate of aromatic dicarboxylic acid used as the base vehicle 1 in the polycondensation reaction is the aromatic dicarboxylic acid component unit f described below.
It is formed from at and alkylene diamine component unit (b). The alkylene diamine salt of an aromatic dicarboxylic acid is prepared by mixing an aromatic dicarboxylic acid and an alkylene diamine in the presence of a solvent such as water, alcohol, or phenol as necessary, usually at 40 to 150°C, preferably at 50 to 120°C. It is produced by heating to. The solvent is removed from this reaction mixture by distillation or other methods, and the alkylene diamine salt of aromatic dicarboxylic acid is obtained by drying.

The lower-order condensate is prepared by combining an aromatic dicarboxylic acid or its ester and an alkylene diamine in the presence of a solvent such as water, alcohol, or phenol as necessary, usually at 60 to 350°C, preferably. is 100 to 350℃
It can be obtained by heating the alkylene diamine salt of the aromatic dicarboxylic acid to 60 to 350°C, preferably 150 to 350°C. can get. [η] (value measured in concentrated sulfuric acid at 30°C) of the lower condensate is usually 0.05 to 1.20 dl/
g, preferably from 0.15 to 1.1 dl/g, particularly preferably from 0.30 to Od7/g, and the melting point is usually in the range from 250 to 340°C.

In the method of the present invention, the aromatic dicarboxylic acid component degree (a
l must be a mixed component consisting of 60 to 85 mol% of terephthalic acid component units and aromatic dicarboxylic acid component q other than terephthalic acid (position 15 to 40 mol%, and furthermore, terephthalic acid component Unit is 62
It is preferable that the amount of aromatic dicarboxylic acid component units other than terephthalic acid component units is in the range of 25 to 38 mol%. When the composition of aromatic dicarboxylic acid component units (al) is less than 60 mol% of terephthalic acid component units and the degree of aromatic dicarboxylic acid components other than terephthalic acid component units is greater than 40 mol%, heat resistance properties such as heat distortion temperature , mechanical properties such as tensile strength, limit Pv value, abrasion resistance, especially sliding properties, chemical resistance,
Chemical and physical properties such as water resistance begin to deteriorate.

In addition, when the composition of the aromatic dicarboxylic acid component unit 1al is such that the ni-position of the terephthalic acid component exceeds 85 mol% and the aromatic dicarboxylic acid component units other than the terephthalic acid component unit are less than 15 mol%, the melting point of the polyamide decreases. If it becomes too high, thermal decomposition occurs during melt molding, resulting in a decrease in mechanical strength and heat resistance.

In the method of the present invention, aromatic dicarboxylic acid component units other than the terephthalic acid component (specifically, as al, Examples include respective component units such as isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc. Among these, isophthalic acid component units are preferred.

In the method of the present invention, the alkylene diamine component unit +b constituting the alkylene diamine salt or lower condensate of aromatic dicarboxylic acid used as a raw material in the polycondensation reaction
1 is a hexamethylene diamine component unit.

In the method of the present invention, the polycondensation reaction of an alkylene diamine salt or a lower condensate of an aromatic dicarboxylic acid is carried out under conditions in which the alkylene diamine salt or a lower condensate of an aromatic dicarboxylic acid maintains a solid phase state, In addition, the temperature at that time must be 100°C lower than the melting point of the polycondensation reaction mixture of the polycondensation system, or lower than the melting point of the polycondensation reaction mixture of the polycondensation system. A low temperature range or a temperature range 5° C. lower than the melting point is preferable because a polyamide with good color tone can be obtained.

Further, the pressure during the polycondensation reaction may be under any of the following conditions: increased pressure, normal pressure, or reduced pressure. During the polycondensation reaction, the temperature of the polycondensation reaction mixture is 10° below the melting point.
If the polycondensation reaction is carried out at a temperature below 0°C, the polycondensation rate will be significantly slowed down, resulting in poor heat resistance properties such as heat distortion temperature, mechanical properties such as tensile strength, critical pv value, abrasion resistance, especially sliding properties, and water resistance. Polyamides with excellent chemical and physical properties such as properties cannot be obtained.

The composition of the polyamide obtained by the method of the present invention is aromatic dicarboxylic acid component units consisting of 60 to 85 mol% of terephthalic acid component units and 40 to 15 mol% of aromatic dicarboxylic acid component units other than terephthalic acid component units. (al and hexamethylenediamine component unit (b)
Its intrinsic viscosity [η] (value measured in concentrated sulfuric acid at 30°C) is usually 0.6 to 3.0 dl.
/g, preferably in the range of 0.9 to 2.5 dl/g, and its melting point is usually in the range of 305 to 350°C, preferably 315 to 350°C.

The polyamide obtained by the method of the present invention can be used as a molding material, a sliding material, and various other uses that require the above-mentioned performance. The polyamide may be blended with conventionally known stabilizers, plasticizers, mold release agents, lubricants, etc., if necessary, and may also be blended with glass fibers, carbon fibers, fully aromatic polyamide fibers, Fillers such as fluororesin, graphite, and molybdenum disulfide can also be blended.

The polyamide produced by the method of the present invention can also be molded by conventional melt molding, injection molding, extrusion molding, compression molding, etc.

Next, the method of the present invention will be specifically explained using examples. In addition, in Examples and Comparative Examples, methods for preparing test pieces and evaluation methods for each performance are shown below.

The following abbreviations used in Table 2 below are Each represents the following compound.

TA: DMT terephthalate: Dimethyl terephthalate IA: DMI isophthalate: Dimethyl isophthalate C6DA: 1,6-diamithexane Preparation of test piece and evaluation method of each performance Polyamide was heated at 100°C for 12 hours under conditions of 1 mm and 11 g.
After drying, uniaxial extrusion tJ at a temperature 20°C higher than the melting point
31 (L/D=28.30 mmφ) to obtain pellets.

After drying for 12 hours at 100℃ and l+11m11g, it was press-molded to 100 kg/100 kg in a nitrogen atmosphere.
After hot pressing at a temperature 20° C. higher than the melting point under a pressure of cA, cold pressing was performed at a temperature of 20° C. to produce a compression molded plate having a thickness of 2 mm to 10 mm. After cutting these molded plates to the dimensions of each test piece listed in Table 1, they were left in an atmosphere at a temperature of 23°C and a relative humidity of 65% for 96 hours, and then tested. 2,50M)
, dimethyl terephthalate 340g (1,75M),
146 g (0.75 M) of dimethyl isophthalate and 0.61 g of ion-exchanged water were charged into a 31 flask and reacted under a N2 atmosphere at a bath temperature of 95° C., and the methanol produced was refluxed for 5 hours. Next, the bath salt was heated to 140°C, methanol and water were distilled off over 4 hours, and then the bath temperature was raised from 140°C to 350°C at a constant rate over 6 hours, and the distillate was distilled off. η] is 0.6 dl/g (30
590 g of a lower-order condensate (measured in concentrated sulfuric acid at 0.degree. C.) was obtained.

Table 2 shows the melting points and [η] of the lower-order condensates.

Next, this low-order condensate was heated at 300°C for 0.7 m while stirring.
Solid phase polymerization was carried out for 12 hours under the condition of 1 g of ml, and [η] was 1.
．． 570 g of polyamide with a yield of 45 dl/g (measured in concentrated sulfuric acid at 30° C.) was obtained. The temperature during solid phase polymerization is always 15°C lower than the melting point of the polycondensation reaction mixture to 40°C. Polymers having different contents of terephthalic acid component units in dicarboxylic acid component units were obtained according to the method described in Example 1, except that the polymerization conditions were changed as shown in Table 1. The results are shown in Table 2.

Example 3 494 g of salt of terephthalic acid and hexamethylene diamine
(1,75M), 212g (0,75M) of the salt of isophthalic acid and hexamethylene diamine, and 400ml of ion-exchanged water were charged into an autoclave, and after expelling dissolved oxygen by replacing with N2 gas, while stirring. Heated to a temperature of 225°C for 2 hours. After that, when the temperature was raised to 300° C. over 3 hours, the pressure rose, so water vapor was discharged outside the system so as to maintain the pressure inside the system at 25 kg/cJ. After maintaining the temperature at 300° C. for 1 hour, the pressure was increased to room temperature over 0.5 hours. After maintaining the temperature at 300° C. for 1 hour, the pressure was reduced to normal pressure over 0.5 hours. Part 6 After that, the temperature was raised to 350℃ and kept at this temperature for 0.5 hours.
η] of 0.8 dl/g (measured in concentrated sulfuric acid at 30°C), 581 g of a lower condensate was obtained.

Next, this lower condensate was heated at 290°C, 7mm under stirring.
Solid phase polymerization was carried out for 8 hours under the conditions of [η] of 1.50 di.
560 g of polyamide (measured in concentrated sulfuric acid at 30°C)
I got it. The temperature during solid phase polymerization was always maintained in the range of 35° C. to 50° C. below the melting point of the polycondensation reaction mixture.

Comparative Examples 3 to 5 Nylon-6,6 (DuPont Zytel 101■
), poly(2,4,4-1-limethylhexamethylene terephthalamide (Dynamit Nohel 1i!J+/Rogamid T0')) and polyacetal (Duracon M-90°" manufactured by Polyplastics). 7

Claims (1)

[Claims] (1) A polyamide is produced by heating an alkylene diamine salt or a lower condensate of an aromatic dicarboxylic acid formed from an aromatic dicarboxylic acid component unit (II) and an alkylene diamine component unit (bl) in a solid state to cause polycondensation. (i) the aromatic dicarboxylic acid component units (al is 60 to 85 mol% of the terephthalic acid component phase and the aromatic dicarboxylic acid component units other than terephthalic acid are 15 to 40%);
(b) is a hexamethylene diamine component unit, and (ii) the polycondensation reaction is carried out under conditions that maintain a solid phase state, and A method for producing polyamide, characterized in that the temperature at that time is 100° C. lower than the melting point of the polycondensation reaction mixture of the polycondensation system or below the melting point.