HK1185900B - Polyamide resins and processes for molding them - Google Patents

Description

Polyamide resin and method for molding same

Technical Field

The present invention relates to a polyamide resin and a method for molding the same, and more particularly, to a polyamide resin having high heat resistance and excellent mechanical properties and a method for molding the same.

Background

Polyamide resins are widely used as engineering plastics having excellent mechanical strength such as impact resistance and friction/abrasion resistance, and also excellent heat resistance and oil resistance in the fields of automobile parts, electronic/electric equipment parts, office automation equipment parts, machine parts, building material/housing equipment-related parts, and the like, and their fields of use have been expanded further in recent years.

As the polyamide resin, for example, a plurality of types such as polyamide 6 and polyamide 66 are known, but unlike polyamide 6 and polyamide 66, m-xylylene adipamide (hereinafter, also referred to as "MXD 6") obtained from m-xylylenediamine and adipic acid has an aromatic ring in the main chain, and is extremely excellent in high rigidity, low water absorption and excellent oil resistance, and further, has a small molding shrinkage rate, and is suitable for precision molding because of its small shrinkage (shrinkage) and warpage (warp) during molding. As a result, MXD6 has been widely used in recent years as a molding material, particularly as an injection molding material, in various fields such as parts of electronic/electric devices, parts of transportation machines such as automobiles, general machine parts, precision machine parts, leisure and sports goods, and parts for civil engineering and construction.

On the other hand, in recent years, market demand for applications requiring high heat resistance is also very high, and for example, reflectors (reflective plates) in LED lighting, LED mounting boards, and the like, high heat resistance is required at the time of production and use thereof.

Patent documents 1 to 4 propose the use of various polyamide resin compositions for the above-mentioned applications. Patent document 1 discloses: a composition comprising a semi-aromatic polyamide comprising terephthalic acid, 1, 9-nonanediamine and 2-methyl-1, 8-octanediamine, titanium dioxide, magnesium hydroxide and a filler. However, the melting point of the polyamide is high, for example, around 306 ℃, but this is not preferable because it has problems such as poor melt flowability, easy degradation of the resin, generation of a large amount of gas, difficulty in molding, and poor productivity.

In such high heat resistance applications, polyamide resins having a melting point of 280 ℃ or higher, particularly more than 300 ℃, are desired, but at present, polyamide resins having such a high melting point and excellent in molding processing have not yet reached industrially satisfactory levels at present.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-257314

Patent document 2: japanese patent laid-open No. 2008-182172

Patent document 3: japanese patent laid-open publication No. 2009-99533

Patent document 4: japanese laid-open patent publication No. 2009-202567

Disclosure of Invention

Problems to be solved by the invention

In view of the above-described situation, an object of the present invention is to provide a polyamide resin having high heat resistance, hardly degraded, and excellent molding processability and mechanical properties.

Means for solving the problems

As a result of intensive studies to achieve the above object, the present inventors have found that a polyamide resin having a specific molecular weight and a specific melting point and having a molar ratio of a reacted diamine component to a dicarboxylic acid component reduced to a specific amount or less, which is composed of a diamine component mainly composed of p-xylylenediamine and mixed with m-xylylenediamine and a dicarboxylic acid component mainly composed of adipic acid and, if necessary, mixed with a linear aliphatic dicarboxylic acid such as sebacic acid, is a polyamide resin suitable for the above object, and have completed the present invention.

That is, according to a first aspect of the present invention, there is provided a polyamide resin comprising a diamine unit containing 70 mol% or more of a xylylenediamine unit and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit,

the xylylenediamine unit is composed of 50 to 95 mol% of p-xylylenediamine and 50 to 5 mol% of m-xylylenediamine,

the linear aliphatic dicarboxylic acid unit is composed of 50 to 100 mol% of adipic acid and 0 to less than 50 mol% of sebacic acid or other linear aliphatic dicarboxylic acids,

the molar ratio of reacted diamine units to reacted dicarboxylic acid units (moles of reacted diamine units/moles of reacted dicarboxylic acid units) is less than 0.994,

the polyamide resin has a number average molecular weight of 10000-25000 and a melting point of 285 ℃ or higher.

Further, according to a second aspect of the present invention, there is provided a polyamide resin, wherein in the first aspect, the terminal amino group concentration is 10 to 100 μ equivalent/g.

Further, according to a third aspect of the present invention, there is provided a polyamide resin, wherein in the first aspect, the terminal carboxyl group concentration is 50 to 200 μ equivalent/g.

Further, according to a fourth aspect of the present invention, there is provided a polyamide resin, wherein, in the first aspect, the ratio of the terminal amino group concentration to the terminal carboxyl group concentration ([ NH ]₂]/[COOH]) Is 0.6 or less.

Further, according to a fifth aspect of the present invention, there is provided a polyamide resin characterized in that, in the first aspect, the melting point exceeds 300 ℃.

Further, according to a sixth aspect of the present invention, there is provided a heat-resistant member obtained by molding the polyamide resin according to the first aspect.

Further, according to a seventh aspect of the present invention, there is provided the heat-resistant member according to the sixth aspect, wherein the heat-resistant member is an LED reflector, an LED mounting board, or a heat dissipating member.

Further, according to an eighth aspect of the present invention, there is provided a method for molding a polyamide resin, characterized by melt-molding a polyamide resin with an extruder or a molding machine and then subjecting the polyamide resin to an amidation reaction, wherein,

the polyamide resin is a polyamide resin formed from diamine units containing 70 mol% or more of xylylenediamine units and dicarboxylic acid units containing 70 mol% or more of linear aliphatic dicarboxylic acid units,

the xylylenediamine unit is composed of 50 to 95 mol% of p-xylylenediamine and 50 to 5 mol% of m-xylylenediamine,

the linear aliphatic dicarboxylic acid unit is composed of 50 to 100 mol% of adipic acid and 0 to less than 50 mol% of sebacic acid or other linear aliphatic dicarboxylic acids,

the molar ratio of reacted diamine units to reacted dicarboxylic acid units (moles of reacted diamine units/moles of reacted dicarboxylic acid units) is less than 0.994,

the polyamide resin has a number average molecular weight of 10000 to 25000 and a melting point of 285 ℃ or higher.

Further, according to a ninth aspect of the present invention, there is provided the method for molding a polyamide resin, wherein in the eighth aspect, the number average molecular weight of the polyamide resin after melt molding is increased by 0.5 to 50% relative to the number average molecular weight before melt molding.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a polyamide resin having high heat resistance, hardly degraded, excellent molding processability, and excellent mechanical properties can be stably provided.

Further, the molding method of the present invention, in which the polyamide resin is melt-molded by an extruder or a molding machine and then subjected to an amidation reaction to increase the molecular weight, can provide a polyamide resin molded article having excellent heat resistance and excellent mechanical properties.

Furthermore, molded articles obtained by molding the polyamide resin of the present invention are expected to be used in various high heat resistant applications such as reflectors for LEDs, substrates for mounting LEDs, and heat dissipating members in fields such as high heat resistant members to which polyamide resins have not been applied so far.

As a factor for showing such a feature that the resin is difficult to degrade, a method of increasing the molecular weight by polymerizing a diamine component and a dicarboxylic acid component in a range of about 1:1 is generally employed in the synthesis of a polyamide resin composed of a diamine and a dicarboxylic acid, but in the present invention, the number of moles of the diamine component/the number of moles of the dicarboxylic acid component is set to a low value of less than 0.994 instead, and the terminal carboxyl group is increased (rich) and the terminal amino group is decreased (under) to prevent degradation of the polyamide resin due to heating at the time of molding. Further, it is considered that the amidation reaction proceeds further in the molding machine, and the molecular weight increases, whereby a molded article having excellent mechanical properties such as bending and high heat resistance can be obtained.

Detailed Description

The polyamide resin of the present invention is characterized by being a polyamide resin comprising a diamine unit containing 70 mol% or more of a xylylenediamine unit and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit,

the xylylenediamine unit is composed of 50 to 95 mol% of p-xylylenediamine and 50 to 5 mol% of m-xylylenediamine,

the linear aliphatic dicarboxylic acid unit is composed of 50 to 100 mol% of adipic acid and 0 to less than 50 mol% of sebacic acid or other linear aliphatic dicarboxylic acids,

the molar ratio of reacted diamine units to reacted dicarboxylic acid units (moles of reacted diamine units/moles of reacted dicarboxylic acid units) is less than 0.994,

the polyamide resin has a number average molecular weight of 10000-25000 and a melting point of 285 ℃ or higher.

The polyamide resin and the method for molding a polyamide resin of the present invention will be described in detail below.

In the present specification, "to" are used in a meaning including, unless otherwise specified, numerical values recited before and after the "to" as a lower limit value and an upper limit value.

The diamine unit of the polyamide resin of the present invention is derived from a diamine component containing 70 mol% or more of xylylenediamine, and the xylylenediamine is composed of 50 to 95 mol% of p-xylylenediamine and 50 to 5 mol% of m-xylylenediamine.

If the content of xylylenediamine is less than 70 mol%, the heat resistance and chemical resistance are lowered. The xylylenediamine is preferably 80 mol%, more preferably 90 mol%, still more preferably 95 mol%, and particularly preferably 98 mol%.

Among xylylenediamines, when p-xylylenediamine is less than 50 mol% (m-xylylenediamine is more than 50 mol%), heat resistance and crystallinity are deteriorated, and when p-xylylenediamine is more than 95 mol% (m-xylylenediamine is less than 5 mol%), moldability is deteriorated.

The preferred ratios are: 55-95 mol% of p-xylylenediamine and 45-5 mol% of m-xylylenediamine.

The dicarboxylic acid unit of the polyamide resin of the present invention is derived from a dicarboxylic acid component comprising 70 mol% or more of a linear aliphatic dicarboxylic acid, and the linear aliphatic dicarboxylic acid component is composed of 50 to 100 mol% of adipic acid, 0 to less than 50 mol% of sebacic acid, or another linear aliphatic dicarboxylic acid.

When the content is within this range, a polyamide resin having good heat resistance and excellent moldability can be obtained.

Preferred dicarboxylic acids used as the linear aliphatic dicarboxylic acid other than adipic acid and sebacic acid are α, ω -linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms, and examples thereof include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid, and dodecanedioic acid, and one kind or two or more kinds thereof may be used in combination.

Preferred ratios of linear aliphatic dicarboxylic acids are: 55 to 100 mol% of adipic acid, 45 to 0 mol% of sebacic acid, and less than 50 to 0 mol% of other linear aliphatic dicarboxylic acids.

As the diamine which is a raw material of the polyamide resin, as diamines other than p-xylylenediamine and m-xylylenediamine and usable in a range of less than 30 mol% of the diamine, aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2, 4-trimethylhexamethylenediamine, and 2,4, 4-trimethylhexamethylenediamine; alicyclic diamines such as 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, 1, 3-diaminocyclohexane, 1, 4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) decahydronaphthalene (including structural isomers), and bis (aminomethyl) tricyclodecane (including structural isomers); diamines having an aromatic ring such as bis (4-aminophenyl) ether, p-phenylenediamine, p-xylylenediamine, and bis (aminomethyl) naphthalene (including structural isomers), and the like, may be used singly or in combination.

When a diamine other than p-xylylenediamine and m-xylylenediamine is used as the raw diamine, the diamine is used in a proportion of less than 30 mol%, preferably 1 to 25 mol%, and particularly preferably 5 to 20 mol% based on the diamine structural unit.

Examples of dicarboxylic acids other than the linear aliphatic dicarboxylic acid which can be used in a range of less than 30 mol% of the dicarboxylic acid include phthalic acid compounds such as isophthalic acid, terephthalic acid, and phthalic acid; naphthalenedicarboxylic acids such as isomers of 1, 2-naphthalenedicarboxylic acid, 1, 3-naphthalenedicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, 1, 6-naphthalenedicarboxylic acid, 1, 7-naphthalenedicarboxylic acid, 1, 8-naphthalenedicarboxylic acid, 2, 3-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid and 2, 7-naphthalenedicarboxylic acid, and one kind or two or more kinds may be used as a mixture.

In addition, monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid; polycarboxylic acids such as trimesic acid and pyromellitic acid; carboxylic acid anhydrides such as pyromellitic anhydride and pyromellitic anhydride, and the like.

When a dicarboxylic acid other than the linear aliphatic dicarboxylic acid is used as the dicarboxylic acid, isophthalic acid is preferably used from the viewpoint of molding processability. The ratio of isophthalic acid is less than 30 mol%, preferably 1 to 25 mol%, and particularly preferably 5 to 20 mol% of the dicarboxylic acid constituent unit.

The polyamide resin of the present invention has a terminal amino group concentration of preferably 10 to 100. mu. equivalents/g, more preferably 15 to 70. mu. equivalents/g, and still more preferably 20 to 50. mu. equivalents/g, and a terminal carboxyl group concentration of preferably 50 to 200. mu. equivalents/g, more preferably 60 to 170. mu. equivalents/g, and still more preferably 70 to 150. mu. equivalents/g.

When the terminal amino group concentration and the terminal carboxyl group concentration are in the above ranges, the molecular weight of the polyamide resin tends to be in an appropriate range, the mechanical properties tend to be more favorable, the resin tends to be less likely to degrade during molding, the generation of gas can be suppressed, and the moldability tends to be favorable.

In addition, the ratio of the concentration of the terminal amino group to the concentration of the terminal carboxyl group ([ NH ]₂]/[COOH]) Preferably 0.7 or less, more preferably 0.6 or less, and particularly preferably 0.5 or less. When the ratio is more than 0.6, the polyamide resin tends to have poor heat resistance and to be easily discolored or to generate gas during molding.

The terminal amino group concentration can be measured by dissolving 0.5g of the polyamide resin in 30ml of a phenol/methanol (4:1) mixed solution at 20 to 30 ℃ with stirring and titrating with 0.01N hydrochloric acid. The terminal carboxyl group concentration can be calculated as follows: 0.1g of polyamide resin was dissolved in 30ml of benzyl alcohol at 200 ℃ and 0.1ml of phenol red solution was added at 160 ℃ to 165 ℃. This solution was titrated with a titration solution (0.01 mol/l KOH concentration) prepared by dissolving 0.132g of KOH in 200ml of benzyl alcohol, and the color was calculated by using the point at which the color changed from yellow to red and did not change any more as an end point.

The melting point of the polyamide resin of the present invention is 285 ℃ or higher, preferably 290 ℃ or higher, more preferably 295 ℃ or higher, further preferably 300 ℃ or higher, and particularly preferably 305 ℃ or higher. The upper limit thereof is preferably about 340 ℃, more preferably 335 ℃ or lower, further preferably 330 ℃ or lower, and particularly preferably 320 ℃ or lower. When the melting point is in the above range, the heat resistance is improved.

The glass transition temperature of the polyamide resin is preferably in the range of 60 to 120 ℃, more preferably 65 to 110 ℃, and particularly preferably 70 to 100 ℃.

In the present invention, the melting point and the glass transition temperature of the polyamide resin can be measured by a Differential Scanning Calorimetry (DSC) method, and refer to melting point and glass transition temperature measured by heating and melting a sample once to eliminate the influence of the thermal process on crystallinity, and then raising the temperature again. Specifically, for example, the polyamide resin is rapidly cooled after being melted by raising the temperature from 30 ℃ to a temperature equal to or higher than the predicted melting point at a rate of 10 ℃/min. Then, the temperature was increased at a rate of 10 ℃/min to a temperature equal to or higher than the melting point, whereby the melting point and the glass transition temperature were determined.

The polyamide resin of the present invention has a number average molecular weight of 10000 to 25000, preferably 11000 to 24000, and more preferably 12000 to 23000. When the number average molecular weight is in such a range, the mechanical strength of the molded article is good, and the moldability is good.

The number average molecular weight referred to herein is the terminal amino group concentration [ NH ] of the polyamide resin according to the following formula₂](. mu.eq/g) and terminal carboxyl group concentration [ COOH)]Calculated (. mu.eq/g).

Number average molecular weight =2000000/([ COOH)]＋[NH₂])

The polyamide resin of the present invention has a molar ratio of reacted diamine units to reacted dicarboxylic acid units (the number of moles of reacted diamine units/the number of moles of reacted dicarboxylic acid units, hereinafter also referred to as "reaction molar ratio") of less than 0.994, preferably less than 0.993, more preferably less than 0.992, and particularly preferably less than 0.991, and the lower limit thereof is preferably 0.970 or more, more preferably 0.975 or more, more preferably 0.980 or more, and particularly preferably 0.985 or more.

The polyamide resin of the present invention has a reaction molar ratio of less than 0.994, and thus is suppressed in resin degradation during molding and has stable fluidity. Further, when melt-molding is performed by an extruder or a molding machine and then the amidation reaction is performed, it becomes easy to perform the reaction in an optimum range without excessively performing the amidation reaction. When the reaction molar ratio is 0.994 or more, the resin may be degraded during molding and gas may be easily generated.

Here, the reaction molar ratio (r) was determined by the following equation.

r=(1-cN-b(C-N))/(1-cC＋a(C-N))

In the formula (I), the compound is shown in the specification,

a：M1/2

b：M2/2

c: 18.015 (molecular weight of Water)

M1: molecular weight of diamine (g/mol)

M2: molecular weight (g/mol) of dicarboxylic acid

N: terminal amino group concentration (equivalent/g)

C: terminal carboxyl group concentration (equivalent/g)

When a polyamide resin is synthesized using monomers having different molecular weights as diamines and dicarboxylic acids, M1 and M2 are naturally calculated from the blending ratio (molar ratio) of the monomers blended as raw materials. In addition, if the synthesis reactor is a completely closed system, the molar ratio of the monomer to be charged and the reaction molar ratio are the same, but the actual synthesis apparatus cannot be a completely closed system, and therefore the molar ratio to be charged and the reaction molar ratio are not necessarily the same. Since the charged monomers are not necessarily completely reacted, the charged molar ratio and the reaction molar ratio are not necessarily equal to each other. Therefore, the reaction molar ratio is a molar ratio of monomers actually reacted, which is determined from the terminal group concentration of the obtained polyamide resin.

The reaction molar ratio of the polyamide resin can be adjusted by changing the reaction conditions such as the charging molar ratio of the raw materials dicarboxylic acid and diamine, the reaction time, the reaction temperature, the dropping rate of xylylenediamine, the degree of pressure reduction in the reactor, and the timing of starting the pressure reduction to appropriate values.

In the case where the method for producing the polyamide resin is a so-called salt method, the reaction may be sufficiently carried out so that the reaction molar ratio is less than 0.994, specifically, for example, the ratio of the raw diamine/the raw dicarboxylic acid is less than 0.994. In the case of the method of continuously adding the diamine dropwise to the molten dicarboxylic acid, the amount of the diamine to be refluxed may be controlled during the addition of the diamine, and the diamine to be added dropwise may be discharged to the outside of the reaction system, in addition to the feed ratio being less than 0.994. Specifically, the diamine may be discharged to the outside of the system by controlling the temperature of the reflux column to an optimum range, controlling the packing of the packed column, and controlling the shape and the packing amount of so-called raschig ring, lycra ring, saddle (saddle) and the like to be appropriate. Further, by shortening the reaction time after the diamine is added dropwise, unreacted diamine can be discharged out of the system. Further, by controlling the diamine dropping rate, unreacted diamine can be discharged out of the reaction system as needed. By these methods, the reaction molar ratio can be controlled within a predetermined range even if the feed ratio is higher than 0.994.

The polyamide resin of the present invention is obtained by polycondensation of a diamine component containing 70 mol% or more of xylylenediamine and a dicarboxylic acid component containing 70 mol% or more of adipic acid, sebacic acid, or other linear aliphatic dicarboxylic acids, and the production method thereof is not particularly limited, and can be produced by a conventionally known method such as a normal pressure melt polymerization method or a pressurized melt polymerization method, and polymerization conditions.

For example, the polyamide can be produced by a method in which a polyamide salt composed of p-xylylenediamine, m-xylylenediamine and adipic acid (further, sebacic acid or the like) is heated under pressure in the presence of water, and the polyamide salt is polymerized in a molten state while removing water and condensed water. Alternatively, the polymer can be produced by a method in which p-xylylenediamine and m-xylylenediamine are directly added to adipic acid (further, sebacic acid or the like) in a molten state, and polycondensation is performed under normal pressure. At this time, p-xylylenediamine and m-xylylenediamine were continuously added, and while the reaction system was heated to a temperature not lower than the melting points of the oligoamide and polyamide to be produced, polycondensation was carried out so that the reaction system was not solidified.

When the polyamide resin is obtained by polycondensation, lactams such as epsilon-caprolactam, omega-laurolactam and omega-heptalactam may be added to the polycondensation reaction system within the range not impairing the performance; 6-aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 9-aminononanoic acid, p-aminomethylbenzoic acid and the like.

In the present invention, the polyamide resin is melt-molded by an extruder or a molding machine and then subjected to an amidation reaction, whereby a molded article having an increased molecular weight and excellent mechanical properties such as flexural strength and high heat resistance can be obtained.

The method of melt molding is not particularly limited. For example, when resin pellets are produced from the polyamide resin of the present invention, a dry blend mixed with other components as necessary may be further melt-kneaded to produce the resin pellets. Among them, a method of melt-kneading using various extruders generally used, such as a single-screw extruder and a twin-screw extruder, is preferable, and a method using a twin-screw extruder is particularly preferable in view of productivity, versatility, and the like. In this case, it is preferable to adjust the melt kneading temperature to 290 to 340 ℃ and the residence time to 10 minutes or less, and it is preferable that the screw has at least one or more, preferably two or more, cross-threaded screw elements and/or kneading disks, and the polyamide resin is retained in the screw and melt kneaded.

In addition, when the polyamide resin is produced into molded articles of various shapes by a commonly used molding method, for example, various molding methods such as injection molding, injection compression molding, blow molding, extrusion molding, sheet molding, and the like, the amidation reaction may be carried out by melt kneading. These molding methods can provide a molded article having high heat resistance, which has an increased molecular weight and excellent mechanical properties such as flexural strength. The molding temperature at this time is preferably 290 to 340 ℃ and the residence time is preferably 10 minutes or less.

When the temperature during melt kneading by the extruder and the molding temperature during molding are set to the above ranges, the amidation reaction of the polyamide resin is promoted, the amidation reaction rate of the polyamide resin is increased, and the molecular weight tends to be increased. This improves the mechanical properties of the molded article obtained by molding the polyamide resin. Further, when the screw and the extrusion temperature are set to the above ranges, extrusion kneading failure, degradation of the resin, and deterioration of the polyamide resin are less likely to occur, and coloring tends to be reduced.

The amidation reaction rate is preferably 0.985 to 0.998, more preferably 0.990 to 0.997, in terms of the state of the polyamide resin before melt molding, that is, the polyamide resin after polymerization. The amidation reaction rate is preferably 0.986 to 0.998 after melt molding. When the amidation reaction rate is 0.998 or more in the polymerization, the polyamide resin is undesirably deteriorated by excessive heat history applied to the polyamide resin during the polymerization and further by heat applied to the polyamide resin during the subsequent molding, or the polyamide resin is discolored during the polymerization. By controlling the amidation reaction rate within such a range, a polyamide resin which generates less gas during molding and has good molding processability can be obtained.

The amidation reaction rate (P) is a ratio of reacted monomers, and in the case of a polyamide resin formed from a diamine and a dicarboxylic acid, it can be calculated from a reaction molar ratio, a number average molecular weight, and molecular weights of the monomers and water, and specifically, it can be calculated according to the following formula.

Amidation reaction rate (P) = (Mn + r (Mn-M1) -M2)/(2r (Mn-c))

In the formula (I), the compound is shown in the specification,

mn: number average molecular weight

r: molar ratio of reaction

c: 18.015 (molecular weight of Water)

M1: molecular weight of diamine (g/mol)

M2: molecular weight (g/mol) of dicarboxylic acid

The increase in the number average molecular weight of the polyamide resin after melt molding is preferably 0.5 to 50% relative to the number average molecular weight before melt molding. The increase rate of the molecular weight is defined as an increase rate (%) of the number average molecular weight after molding relative to the number average molecular weight before molding, more preferably 1 to 40%, further preferably 3 to 30%, and particularly preferably 5 to 20%.

Examples of the molded article obtained by using the polyamide resin of the present invention include various molded articles such as films, sheets, laminated films, laminated sheets, pipes, hoses, pipes, profile extrusions, hollow containers, bottles, fibers, and parts having various shapes.

The molded article obtained by using the polyamide resin of the present invention can be applied to various parts requiring heat resistance, and examples thereof include parts for electric/electronic devices, parts for transportation equipment such as automobiles, general machine parts, precision machine parts, and the like, and is particularly suitable for reflectors for LEDs, substrates for mounting LEDs, and heat dissipation parts.

The polyamide resin of the present invention may contain a phosphorus compound for the purpose of improving the processing stability during melt molding or for the purpose of preventing coloration of the polyamide resin. As the phosphorus compound, a phosphorus compound containing an alkali metal or an alkaline earth metal is suitably used, and examples thereof include phosphates, hypophosphites, and phosphites of sodium, magnesium, calcium, and the like. Among these, hypophosphites containing an alkali metal or an alkaline earth metal are preferable because the effect of preventing coloration of the polyamide resin is particularly excellent. When a phosphorus compound is used, it is desirable to contain the phosphorus compound in the polyamide resin so that the phosphorus atom concentration in the finally obtained polyamide resin becomes 1ppm or more and 200ppm or less, preferably 5ppm or more and 160ppm or less, and more preferably 10ppm or more and 100ppm or less.

In addition, in the polyamide resin of the present invention, additives such as a lubricant, a delustering agent, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a nucleating agent, a plasticizer, a flame retardant, an antistatic agent, a color inhibitor, and a gelation inhibitor may be added in addition to the above-mentioned phosphorus compound within a range in which the effects of the present invention are not impaired.

It is also preferable to blend a carbodiimide compound in the polyamide resin of the present invention. The carbodiimide compound is preferably an aromatic, aliphatic or alicyclic polycarbodiimide compound produced by various methods. Among these, from the viewpoint of melt kneading property at the time of extrusion or the like, an aliphatic or alicyclic polycarbodiimide compound is preferably used, and an alicyclic polycarbodiimide compound is more preferably used.

These carbodiimide compounds can be produced by subjecting an organic polyisocyanate to a decarboxylation condensation reaction. Examples thereof include: and a method of synthesizing various organic polyisocyanates by decarboxylation condensation reaction at a temperature of about 70 ℃ or higher in an inert solvent or without using a solvent in the presence of a carbodiimidization catalyst. The content of isocyanate groups is preferably 0.1 to 5%, more preferably 1 to 3%. When the content of the isocyanate group is in the above range, the reaction with the polyamide resin tends to be easy and the hydrolysis resistance tends to be good.

Examples of the organic polyisocyanate which is a raw material for synthesizing the carbodiimide compound include various organic diisocyanates such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate, and mixtures thereof.

Specific examples of the organic diisocyanate include 1, 5-naphthalene diisocyanate, 4 '-diphenylmethane diisocyanate, 4' -diphenyldimethylmethane diisocyanate, 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1, 4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4, 4-diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2, 6-diisopropylphenyl isocyanate, 1,3, 5-triisopropylbenzene-2, 4-diisocyanate, and, Methylene bis (4, 1-cyclohexylene) -diisocyanate, and the like, and two or more of them may be used in combination. Among these, dicyclohexylmethane-4, 4-diisocyanate and methylenebis (4, 1-cyclohexylene) -diisocyanate are preferred.

In order to block the terminal of the carbodiimide compound and control the degree of polymerization thereof, it is also preferable to use a blocking agent such as monoisocyanate. Examples of the monoisocyanate include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate, and the like, and two or more kinds may be used in combination.

The blocking agent is not limited to the above-mentioned monoisocyanate, and may be an active hydrogen compound which can react with isocyanate. Examples of such active hydrogen compounds include compounds having an-OH group such as methanol, ethanol, phenol, cyclohexanol, N-methylethanolamine, polyethylene glycol monomethyl ether, and polypropylene glycol monomethyl ether among aliphatic, aromatic, and alicyclic compounds; secondary amines such as diethylamine and dicyclohexylamine; primary amines such as butylamine and cyclohexylamine; carboxylic acids such as succinic acid, benzoic acid, and cyclohexanecarboxylic acid; and mercaptans such as ethanethiol, allylmercaptan, and thiophenol, and compounds having an epoxy group, and two or more thereof may be used in combination.

Examples of the carbodiimidization catalyst include phospholene oxides such as 1-phenyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, and 3-phospholene isomers thereof; and metal catalysts such as tetrabutyl titanate, among which 3-methyl-1-phenyl-2-phospholene-1-oxide is suitable from the viewpoint of reactivity. Two or more carbodiimidization catalysts may be used in combination.

The carbodiimide compound is preferably contained in an amount of 0.1 to 2 parts by mass, more preferably 0.2 to 1.5 parts by mass, and still more preferably 0.3 to 1.5 parts by mass, based on 100 parts by mass of the polyamide resin. When the amount is less than 0.1 part by mass, hydrolysis resistance is insufficient, discharge unevenness is likely to occur during melt kneading such as extrusion, and melt kneading tends to be insufficient. On the other hand, when the amount exceeds 2 parts by mass, the viscosity during melt kneading is significantly increased, and melt kneading and molding processability are liable to be deteriorated.

In addition, a stabilizer is preferably blended in the polyamide resin of the present invention. As the stabilizer, for example, phosphorus-based, hindered phenol-based, hindered amine-based, organic sulfur-based, oxalic acid aniline-based, aromatic primary amine-based and other organic stabilizers, and copper compound, halide and other inorganic stabilizers are preferable. The phosphorus-based stabilizer is preferably a phosphite compound or a phosphonite compound.

Examples of the phosphite compound include distearylpentaerythritol diphosphite, dinonylphenylpentaerythritol diphosphite, bis (2, 4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-ethylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-isopropylphenyl) pentaerythritol diphosphite, bis (2,4, 6-tri-t-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-sec-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-t-octylphenyl) pentaerythritol diphosphite, dinonylphenylpentaerythritol diphosphite, and mixtures thereof, Bis (2, 4-dicumylphenyl) pentaerythritol diphosphite, etc., and bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2, 4-dicumylphenyl) pentaerythritol diphosphite are particularly preferable.

Examples of the phosphonite compound include tetrakis (2, 4-di-tert-butylphenyl) -4,4 ' -biphenyl diphosphonite, tetrakis (2, 5-di-tert-butylphenyl) -4,4 ' -biphenyl diphosphonite, tetrakis (2,3, 4-trimethylphenyl) -4,4 ' -biphenyl diphosphonite, tetrakis (2, 3-dimethyl-5-ethylphenyl) -4,4 ' -biphenyl diphosphonite, tetrakis (2, 6-di-tert-butyl-5-ethylphenyl) -4,4 ' -biphenyl diphosphonite, tetrakis (2,3, 4-tributylphenyl) -4,4 ' -biphenyl diphosphonite, tetrakis (2,4, 6-tri-tert-butylphenyl) -4,4 ' -biphenyl diphosphonite, and the like, tetrakis (2, 4-di-tert-butylphenyl) -4, 4' -biphenylene diphosphonite is particularly preferred.

Examples of the hindered phenol-based stabilizer include n-octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 1, 6-hexanediol-bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], 3, 9-bis [1, 1-dimethyl-2- { β - (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy } ethyl ] -2,4,8, 10-tetraoxaspiro [5,5] undecane, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate ] (see examples of the hindered phenol-based stabilizer, 3, 5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, 2-thio-diethylenebis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxy-hydrocinnamamide), and the like.

Among these, n-octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 1, 6-hexanediol-bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], 3, 9-bis [1, 1-dimethyl-2- { beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy } ethyl ] -2,4,8, 10-tetraoxaspiro [5,5] undecane, N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxy-hydrocinnamamide).

Examples of the hindered amine-based stabilizer include known hindered amine compounds having a 2,2,6, 6-tetramethylpiperidine skeleton. Specific examples of the hindered amine-based compound include 4-acetoxy-2, 2,6, 6-tetramethylpiperidine, 4-stearoyloxy-2, 2,6, 6-tetramethylpiperidine, 4-acryloyloxy-2, 2,6, 6-tetramethylpiperidine, 4-phenylacetyloxy-2, 2,6, 6-tetramethylpiperidine, 4-benzoyloxy-2, 2,6, 6-tetramethylpiperidine, 4-methoxy-2, 2,6, 6-tetramethylpiperidine, 4-stearyloxy-2, 2,6, 6-tetramethylpiperidine, 4-cyclohexyloxy-2, 2,6, 6-tetramethylpiperidine, 4-benzyloxy-2, 2,6, 6-tetramethylpiperidine, 4-phenoxy-2, 2,6, 6-tetramethylpiperidine, 4-ethylcarbamoyloxy-2, 2,6, 6-tetramethylpiperidine, 4-cyclohexylcarbamoyloxy-2, 2,6, 6-tetramethylpiperidine, 4-phenylcarbamoyloxy-2, 2,6, 6-tetramethylpiperidine, bis (2,2,6, 6-tetramethyl-4-piperidyl) carbonate, bis (2,2,6, 6-tetramethyl-4-piperidyl) oxalate, bis (2,2,6, 6-tetramethyl-4-piperidyl) malonate, bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6, 6-tetramethyl-4-piperidyl) adipate, bis (2,2,6, 6-tetramethyl-4-piperidyl) terephthalate, 1, 2-bis (2,2,6, 6-tetramethyl-4-piperidyloxy) ethane, α' -bis (2,2,6, 6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6, 6-tetramethyl-4-piperidyltoluene) -2, 4-dicarbamate, bis (2,2,6, 6-tetramethyl-4-piperidyl) hexamethylene-1, 6-dicarbamate, tris (2,2,6, 6-tetramethyl-4-piperidyl) -benzene-1, 3, 5-tricarboxylate, tris (2,2,6, 6-tetramethyl-4-piperidyl) -benzene-1, 3, 4-tricarboxylate, 1- [2- { 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy } butyl ] -4- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ]2,2,6, 6-tetramethylpiperidine, a condensate of 1,2,3, 4-butanetetracarboxylic acid with 1,2,2,6, 6-pentamethyl-4-piperidinol with β, β, β ', β', -tetramethyl-3, 9- [2,4,8, 10-tetraoxaspiro (5,5) undecyl ] diethanol, a mixture of the above-mentioned two components, and a process for producing the product, A polycondensate of dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2, 2,6,6, -tetramethylpiperidine, 1, 3-benzenedicarboxylic acid amide-N, N' -bis (2,2,6, 6-tetramethyl-4-piperidyl), and the like.

Examples of the hindered amine compound include those sold under the trade names "ADK STAB LA-52, LA-57, LA-62, LA-67, LA-63P, LA-68LD, LA-77, LA-82 and LA-87" manufactured by ADEKA CORPORATION; trade names "TINUVIN 622, 944, 119, 770, 144" manufactured by Ciba Specialty Chemicals inc; trade name "SUMISORB 577" manufactured by Sumitomo Chemical Company; trade names "CYASORBUV-3346, 3529, 3853" manufactured by American Cyanamid Company, and trade name "Nylostab S-EED" manufactured by Clariant Japan.

Examples of the organic sulfur-based stabilizer include organic thioacid-based compounds such as didodecylthiodipropionate, ditetradecylthiodipropionate, dioctadecylthiodipropionate, pentaerythritol tetrakis (3-dodecylthiopropionate) and thiobis (N-phenyl-. beta. -naphthylamine); mercaptobenzimidazole compounds such as 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole and metal salts of 2-mercaptobenzimidazole; dithiocarbamate compounds such as metal salts of diethyldithiocarbamate and metal salts of dibutyldithiocarbamate; and thiourea-based compounds such as 1, 3-bis (dimethylaminopropyl) -2-thiourea and tributylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropyl xanthate, trilauryl trithiophosphite, and the like.

Among these, mercaptobenzimidazole compounds, dithiocarbamic acid compounds, thiourea compounds and organic thioacid compounds are preferable, and mercaptobenzimidazole compounds and organic thioacid compounds are more preferable. In particular, a thioether-based compound having a thioether structure can be suitably used because it takes oxygen from an oxidized substance and reduces it. Specifically, 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, ditetradecylthiodipropionate, dioctadecylthiodipropionate, and pentaerythritol tetrakis (3-dodecylthiopropionate) are more preferable, ditetradecylthiodipropionate, pentaerythritol tetrakis (3-dodecylthiopropionate), and 2-mercaptomethylbenzimidazole are further more preferable, and pentaerythritol tetrakis (3-dodecylthiopropionate) is particularly preferable.

The molecular weight of the organic sulfur compound is usually 200 or more, preferably 500 or more, and its upper limit is usually 3000.

As the oxalic anilide-based stabilizer, there may be preferably mentioned 4,4 ' -dioctyloxyoxanilide, 2 ' -diethoxyoxanilide, 2 ' -dioctyloxy-5, 5 ' -di-tert-butoxanilide, 2 ' -didodecyloxy-5, 5 ' -di-tert-butoxanilide, 2-ethoxy-2 ' -ethyloxanilide, N ' -bis (3-dimethylaminopropyl) oxanilide, 2-ethoxy-5-tert-butyl-2 ' -ethoxyoxanilide (ethoxanilide) and a mixture thereof with 2-ethoxy-2 ' -ethyl-5, 4 ' -di-tert-butoxanilide, a mixture of o-methoxy-di-substituted oxanilide and p-methoxy-di-substituted oxanilide, a mixture of o-ethoxy-2 ' -ethyl-5, 4 ' -di-tert-butoxanilide, a mixture of o-methoxy, Mixtures of o-ethoxy-disubstituted oxanilides and p-ethoxy-disubstituted oxanilides, and the like.

The aromatic secondary amine-based stabilizer is preferably a compound having a diphenylamine skeleton, a compound having a phenylnaphthylamine skeleton, or a compound having a dinaphthylamine skeleton, and more preferably a compound having a diphenylamine skeleton or a compound having a phenylnaphthylamine skeleton. Specific examples thereof include compounds having a diphenylamine skeleton such as p, p '-dialkyldiphenylamine (having 8 to 14 carbon atoms in the alkyl group), octylated diphenylamine, 4' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine, p- (p-toluenesulfonamide) diphenylamine, N '-diphenyl-p-phenylenediamine, N-phenyl-N' -isopropyl-p-phenylenediamine, N-phenyl-N '- (1, 3-dimethylbutyl) p-phenylenediamine and N-phenyl-N' - (3-methacryloyloxy-2-hydroxypropyl) p-phenylenediamine; compounds having a phenylnaphthylamine skeleton such as N-phenyl-1-naphthylamine and N, N' -di-2-naphthylp-phenylenediamine; and compounds having a dinaphthylamine skeleton such as 2,2 ' -dinaphthylamine, 1,2 ' -dinaphthylamine, and 1,1 ' -dinaphthylamine. Among these, 4 ' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine, N ' -di-2-naphthyl-p-phenylenediamine and N, N ' -diphenyl-p-phenylenediamine are more preferable, and N, N ' -di-2-naphthyl-p-phenylenediamine and 4,4 ' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine are particularly preferable.

As the inorganic stabilizer, a copper compound and a halide are preferable.

The copper compound is a copper salt of various inorganic acids or organic acids, and does not contain a halide described later. The copper may be any of monovalent copper and divalent copper, and specific examples of the copper salt include natural minerals such as hydrotalcite, chromite (stinhite), and pyrolite, in addition to copper chloride, copper bromide, copper iodide, copper phosphate, and copper stearate.

Examples of the halide used as the inorganic stabilizer include halides of alkali metals or alkaline earth metals; ammonium halides and quaternary ammonium halides of organic compounds; examples of the organic halide such as an alkyl halide and an aryl halide include ammonium iodide, stearyl triethylammonium bromide, and benzyl triethylammonium iodide. Among these, halogenated alkali metal salts such as potassium chloride, sodium chloride, potassium bromide, potassium iodide, and sodium iodide are suitable.

The use of a combination of a copper compound and a halide, particularly a combination of a copper compound and a halogenated alkali metal salt is preferable because it exerts excellent effects in terms of thermal discoloration resistance and weather resistance (light resistance). For example, when a copper compound is used alone, the molded article may be colored reddish brown due to copper, and this coloring is not preferable for the intended use. In this case, the copper compound and the halide are used in combination, whereby the discoloration to reddish brown can be prevented.

Among the above stabilizers, in the present invention, organic sulfur-based, aromatic secondary amine-based and inorganic stabilizers are particularly preferable from the viewpoints of processing stability during melt molding, heat aging resistance, appearance of molded articles and prevention of coloring.

The content of these stabilizers is usually 0.01 to 1 part by mass, preferably 0.01 to 0.8 part by mass, relative to 100 parts by mass of the polyamide resin.

The polyamide resin of the present invention may be blended with an inorganic filler within a range not impairing the object of the present invention, and examples thereof include a glass filler (glass fiber, ground glass fiber (milled fiber), glass flake, glass bead, etc.), a calcium silicate filler (wollastonite, etc.), mica, talc, kaolin, potassium titanate whisker, boron nitride, carbon fiber, etc., and two or more of these may be used in combination.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

(example 1)

A reaction vessel equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping funnel, a nitrogen inlet tube, and a strand die was charged with precisely weighed 8.767kg of adipic acid (60mol) and 17.01g of calcium hypophosphite (Ca (pH)₂O₂)₂) (350 ppm in terms of phosphorus atom concentration in the polyamide resin), 8.75g of sodium acetate, nitrogen gas replacement, nitrogen pressure to 0.3MPa, stirring while heating to 170 degrees, adipic acid uniform melting.

8172kg of a mixed diamine (60mol) of m-xylylenediamine and p-xylylenediamine in a ratio of 1:9 was added dropwise thereto under stirring, and the pressure was controlled to 0.5 MPa. Meanwhile, while a predetermined amount of unreacted mixed diamine was discharged out of the system together with the produced condensation water through a partial condenser and a cooler, the temperature in the system was continuously raised to 330 ℃. Controlling the temperature of the partial condenser within the range of 145-147 ℃. After the completion of the dropwise addition of the mixed xylylenediamine, the melt polymerization reaction was continued with the internal temperature set to 330 ℃. After the completion of the diamine addition, the pressure was reduced at a rate of 0.4 MPa/hr and the pressure was reduced to normal pressure over 60 minutes. Thereafter, the pressure was reduced at a rate of 0.002 MPa/min and the pressure was reduced to 0.08MPa for 20 minutes. Thereafter, the reaction was continued at 0.08MPa until the torque of the stirring apparatus reached a predetermined value. The reaction time at 0.08MPa was 10 minutes.

Thereafter, the inside of the system was pressurized with nitrogen, and the polymer was taken out from the strand die and pelletized to obtain about 20kg of a polyamide resin. The resulting pellets were dried under vacuum at 150 ℃ for 7 hours.

The polyamide resin has a melting point (Tm), a glass transition temperature (Tg), a number average molecular weight (Mn), a reaction molar ratio (r), and a terminal amino group concentration ([ NH ]₂]) Terminal carboxyl group concentration ([ COOH ]]) And their ratio ([ NH ]₂]/[COOH]) The amidation reaction rate was as shown in table 1.

The evaluation methods thereof are as follows.

(1) Melting point (Tm) and glass transition temperature (Tg):

the melting point and the glass transition temperature were determined by heating the polyamide resin from 30 ℃ to a temperature equal to or higher than the predicted melting point at a rate of 10 ℃/min by Differential Scanning Calorimetry (DSC) using DSC-60 manufactured by SHIMADZU CORPORATION, then rapidly cooling the molten polyamide resin, and subsequently heating the molten polyamide resin to a temperature equal to or higher than the melting point at a rate of 10 ℃/min.

(2) Number average molecular weight (Mn):

the terminal amino group concentration [ NH ] of the polyamide resin was determined by neutralization titration as follows₂](. mu.eq/g) and terminal carboxyl group concentration [ COOH)](. mu. eq/g) was calculated by the following equation.

Number average molecular weight =2000000/([ COOH)]＋[NH₂])

(3) Reaction molar ratio (r):

the calculation is performed by the following equation.

r=(1-cN-b(C-N))/(1-cC＋a(C-N))

In the formula (I), the compound is shown in the specification,

a：M1/2

b：M2/2

c：18.015

m1: molecular weight of diamine (g/mol)

M2: molecular weight (g/mol) of dicarboxylic acid

N: terminal amino group concentration (equivalent/g)

C: terminal carboxyl group concentration (equivalent/g)

(4) Terminal amino group concentration ([ NH ]₂])：

0.5g of a polyamide resin was precisely weighed, dissolved in 30ml of a phenol/methanol (4:1) mixed solution at 20 to 30 ℃ under stirring, and then neutralized and titrated with 0.01N hydrochloric acid to obtain the polyamide resin.

(5) Terminal carboxyl group concentration ([ COOH ]):

0.1g of polyamide resin was precisely weighed, dissolved in 30ml of benzyl alcohol under stirring at 200 ℃ for about 15 minutes in a nitrogen stream, and after complete dissolution, cooled to 165 ℃ under a nitrogen stream, and 0.1ml of phenol red solution was added under stirring. The solution was maintained at 160 to 165 ℃ and titrated with a titration solution (0.01 mol/l in terms of KOH) prepared by dissolving 0.132g of KOH in 200ml of benzyl alcohol, and the solution was determined with the point at which the color of the solution changed from yellow to red and did not change any more as an end point.

(6) Terminal amino group concentration/terminal carboxyl group concentration ([ NH ]₂]/[COOH])：

Calculated from the above concentrations.

(7) Amidation reaction rate (P):

the calculation is performed by the following equation.

P=(Mn＋r(Mn-M1)-M2)/(2r(Mn-c))

In the formula (I), the compound is shown in the specification,

mn: number average molecular weight

r: molar ratio of reaction

c: 18.015 (molecular weight of Water)

M1: molecular weight of diamine (g/mol)

M2: molecular weight (g/mol) of dicarboxylic acid

(examples 2 to 5, comparative examples 1 to 3)

A polyamide resin was obtained in the same manner as in production example 1, except that the mixing ratio of m-xylylenediamine and p-xylylenediamine and the mixing ratio of sebacic acid and adipic acid in production example 1 were changed to the ratios described in table 1.

The evaluation results of the obtained polyamide resins are shown in tables 1 to 2.

(evaluation of Molding of Polyamide resins of examples 1 to 5 and comparative examples 1 to 3)

Next, 20ppm of calcium stearate as a stabilizer was added to each of the polyamide resins obtained in examples 1 to 5 and comparative examples 1 to 3, and the resulting mixture was mixed by a tumbler, and then an ISO test piece having a thickness of 4mm was produced by an injection molding machine 100T manufactured by FANUC Ltd under conditions of a cylinder temperature of +20 to 30 ℃ which is the melting point of the polyamide resin and a mold temperature of 60 to 90 ℃. The test piece was further kept at 150 ℃ for 1 hour and heat-treated.

The flexural modulus (GPa) of the test piece thus obtained was measured according to JIS K7171 using a tensile-compression tester (Strograph) manufactured by Toyoseiki Seisaku-sho at a measurement temperature of 23 ℃ and a measurement humidity of 50% RH.

The number average molecular weight of the test piece thus obtained was measured by the method described above. In addition, the increase rate (%) of the number average molecular weight after molding relative to the number average molecular weight before molding was also obtained.

The results are shown in tables 1 to 2.

[ Table 1]

[ Table 2]

Industrial applicability

The polyamide resin of the present invention has high heat resistance, excellent molding processability and excellent mechanical properties, and a molding method in which melt molding is performed by an extruder or a molding machine and then amidation reaction is performed to increase the molecular weight can provide a polyamide resin molded product having excellent heat resistance and excellent mechanical properties.

Claims (9)

1. A polyamide resin characterized by being a polyamide resin formed from a diamine unit containing 70 mol% or more of a xylylenediamine unit and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit,

the xylylenediamine unit is composed of 50 to 95 mol% of p-xylylenediamine and 50 to 5 mol% of m-xylylenediamine,

the linear aliphatic dicarboxylic acid unit is composed of 50 to 100 mol% of adipic acid and 0 to less than 50 mol% of sebacic acid or other linear aliphatic dicarboxylic acids,

the molar ratio of reacted diamine units to reacted dicarboxylic acid units (moles of reacted diamine units/moles of reacted dicarboxylic acid units) is less than 0.994,

the polyamide resin has a number average molecular weight of 10000-25000 and a melting point of 285 ℃ or higher.

2. The polyamide resin according to claim 1, wherein the concentration of the terminal amino group is 10 to 100. mu. equivalents/g.

3. The polyamide resin according to claim 1, wherein the concentration of the terminal carboxyl group is 50 to 200. mu. equivalents/g.

4. The polyamide resin as claimed in claim 1, wherein the ratio of the terminal amino group concentration to the terminal carboxyl group concentration ([ NH ]₂]/[COOH]) Is 0.6 or less.

5. Polyamide resin according to claim 1, characterized in that the melting point is above 300 ℃.

6. A heat-resistant member obtained by molding the polyamide resin according to claim 1.

7. The heat-resistant member according to claim 6, wherein the heat-resistant member is a reflector for LED, a substrate for LED mounting, or a heat-dissipating member.

8. A method for molding a polyamide resin, characterized by melt-molding a polyamide resin in an extruder or a molding machine and then subjecting the polyamide resin to an amidation reaction,

the polyamide resin is a polyamide resin formed from diamine units containing 70 mol% or more of xylylenediamine units and dicarboxylic acid units containing 70 mol% or more of linear aliphatic dicarboxylic acid units,

the xylylenediamine unit is composed of 50 to 95 mol% of p-xylylenediamine and 50 to 5 mol% of m-xylylenediamine,

the linear aliphatic dicarboxylic acid unit is composed of 50 to 100 mol% of adipic acid and 0 to less than 50 mol% of sebacic acid or other linear aliphatic dicarboxylic acids,

the molar ratio of reacted diamine units to reacted dicarboxylic acid units (moles of reacted diamine units/moles of reacted dicarboxylic acid units) is less than 0.994,

the polyamide resin has a number average molecular weight of 10000 to 25000 and a melting point of 285 ℃ or higher.

9. The method of claim 8, wherein the number average molecular weight of the polyamide resin after melt molding is increased by 0.5 to 50% relative to the number average molecular weight of the polyamide resin before melt molding.