polyamide

Abstract

A polyamide which comprises a diamine unit and a dicarboxylic acid unit, wherein: not less than 0.1% by mole but less than 36% by mole of a diamine unit (X) is contained in the diamine unit; and the diamine unit (X) is derived from an aliphatic diamine which has from 6 to 10 carbon atoms, wherein if a carbon atom to which an arbitrary one of the amino groups is bonded is taken to be in the 1-position, an alkyl group having 2 or 3 carbon atoms is bonded to the carbon atom in the 2-position.

Description

[Technical Field]

[0001] The present invention relates to a polyamide containing a specific branched diamine unit and a dicarboxylic acid unit. [Background technology]

[0002] Crystalline polyamides, such as nylon 6 and nylon 66, are widely used in industrial parts due to their excellent heat resistance, mechanical properties, moldability, etc. For example, in automotive applications, the use of resins instead of metal parts is progressing in order to reduce weight and increase design flexibility, and crystalline polyamides, which have excellent properties as described above, are widely used. However, the performance requirements for plastic materials are becoming increasingly stringent in order to improve fuel efficiency and comply with environmental regulations, and materials with better performance in terms of heat resistance, etc. are being sought. Furthermore, to reduce the manufacturing costs of parts, there is a demand for materials with a fast crystallization rate, which is the time it takes for the material to cool from a molten state and solidify. A fast crystallization rate can shorten the time required to mold a single part, improving production efficiency.

[0003] For example, Patent Document 1 discloses that a polyamide that simultaneously satisfies requirements for fluidity, toughness, rigidity, etc. can be obtained by including at least 50 mol % of diamine units with a branched structure in the main chain of the polyamide. Patent Document 2 also discloses a method for producing a polyamide composition that includes diamine units with methyl or ethyl branches. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-80055 [Patent Document 2] Special Publication No. 2017-517594 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Documents 1 and 2 describe methyl groups, ethyl groups, n-propyl groups, and the like as substituents branched from the main chain of the structural unit derived from diamine that forms the polyamide. However, the only specific examples given are diamines having methyl groups as branched chains. Neither document specifically discloses branched diamines having a branched chain with a substituent having more carbon atoms than methyl groups, and the effect of having a branched chain with two or more carbon atoms is unclear.

[0006] As mentioned above, there is a demand for materials with a high crystallization rate, while there is also a need for physical properties such as heat resistance that are inherent to crystalline polyamides, and there is a demand for a material that can provide both of these physical properties.

[0007] Therefore, the present invention provides a polyamide having an excellent crystallization rate and heat resistance. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the present inventors have conceived the following invention and found that the problems can be solved. That is, the present invention is as follows.

[0009] 1. A polyamide comprising diamine units and dicarboxylic acid units, The diamine units contain diamine units (X) in an amount of 0.1 mol % or more and less than 36 mol %; The diamine unit (X) is a diamine unit derived from an aliphatic diamine having 6 to 10 carbon atoms and having an alkyl group having 2 or 3 carbon atoms bonded to the carbon atom at the second position, when the carbon atom to which any one amino group is bonded is the first position. polyamide. [Effects of the Invention]

[0010] According to the present invention, a polyamide having an excellent crystallization rate and heat resistance can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes an example of an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment"). However, the embodiment described below is merely an example for embodying the technical idea of ​​the present invention, and the present invention is not limited to the following description. In addition, although preferred embodiments are shown in this specification, a combination of two or more of the individual preferred embodiments is also a preferred embodiment. When there are several numerical ranges for matters shown as numerical ranges, the lower limit and upper limit can be selectively combined to form a preferred embodiment. In this specification, when a numerical range is stated as "XX to YY", it means "XX or more and YY or less." Furthermore, in this specification, the term "unit" (where "" indicates a monomer) means "a structural unit derived from", for example, a "dicarboxylic acid unit" means "a structural unit derived from a dicarboxylic acid", and a "diamine unit" means "a structural unit derived from a diamine".

[0012] [polyamide] The polyamide of this embodiment comprises diamine units and dicarboxylic acid units. In this embodiment, the diamine unit is characterized by containing a specific amount of diamine units (X) derived from an aliphatic diamine having 6 to 10 carbon atoms and having an alkyl group having 2 or 3 carbon atoms bonded to the carbon atom at the second position, when the carbon atom to which any one amino group is bonded is taken as the first position. Generally, when a polymer skeleton contains a component with a large excluded volume, such as a branched chain, the polymer tends to have a slower crystallization rate because the molecular chains are less likely to be regularly arranged. However, in this embodiment, by including a specific amount of a diamine component having an alkyl group with 2 or 3 carbon atoms, such as an ethyl group or a propyl group, as a branched chain, the crystallization rate was unexpectedly increased. Generally, polyamides having bulky substituents such as branched chains tend to have difficulty in forming a crystalline structure and to have a lower melting point. However, the polyamide of this embodiment exhibits only a small decrease in melting point and excellent heat resistance, even when it has relatively bulky substituents with 2 or 3 carbon atoms, such as ethyl or propyl groups, in its branched chains. Furthermore, the lower the molecular mobility of the amorphous portion, the higher the glass transition temperature. Therefore, the glass transition temperature generally tends to be lower when a component with high molecular mobility, such as a branched chain, is contained. However, the polyamide of this embodiment surprisingly exhibits only a small decrease in glass transition temperature and can exhibit excellent heat resistance. One of the reasons why the above-mentioned effects are obtained in this embodiment is thought to be that the number of carbon atoms in the branched chain, the position of the branched chain, and the amount of the branched chain, which are possessed by the diamine units contained in the polyamide, affect the improvement of the crystallization rate while maintaining excellent heat resistance, but the detailed reason is unknown.

[0013] (diamine units) <Diamine unit (X)> The diamine unit contains a diamine unit (X) derived from an aliphatic diamine having 6 to 10 carbon atoms and having an alkyl group having 2 or 3 carbon atoms bonded to the carbon atom at the second position, when the carbon atom to which any one amino group is bonded is considered to be the first position. The diamine unit (X) is derived from an aliphatic diamine having a structure in which, assuming a linear aliphatic chain having carbon atoms to which two amino groups are bonded at both ends, one of the hydrogen atoms on the carbon atom at position 2 adjacent to the carbon atom at position 1 to which any one of the amino groups is bonded is substituted with an alkyl group having 2 or 3 carbon atoms.

[0014] The number of carbon atoms in the branched aliphatic diamine unit forming the diamine unit (X) is preferably 8 to 10, and more preferably 9. When the number of carbon atoms is within the above range, the polymerization reaction between the dicarboxylic acid and the diamine proceeds smoothly, and the physical properties of the polyamide are more likely to be improved.

[0015] In the branched aliphatic diamine unit constituting the diamine unit (X), the alkyl group having 2 or 3 carbon atoms is preferably at least one selected from the group consisting of an ethyl group, a propyl group, and an isopropyl group, and more preferably at least one selected from the group consisting of an ethyl group and a propyl group. If the alkyl group has 1 or 4 or more carbon atoms, the crystallization rate may not be improved and heat resistance may be reduced. The branched aliphatic diamine forming the diamine unit (X) may have a branched chain such as a methyl group (referred to as "another branched chain") on a carbon other than the carbon at position 2, as long as the effects of the present invention are not impaired. The number of other branched chains is preferably one or less, and the diamine unit (X) more preferably does not contain any other branched chains.

[0016] Examples of the diamine unit (X) include structural units derived from 2-ethyl-1,4-butanediamine, 2-ethyl-1,5-pentanediamine, 2-ethyl-1,6-hexanediamine, 2-ethyl-1,7-heptanediamine, 2-ethyl-1,8-octanediamine, 2-propyl-1,5-pentanediamine, 2-propyl-1,6-hexanediamine, 2-propyl-1,7-heptanediamine, and 2,4-diethyl-1,6-hexanediamine. Only one type of these structural units may be contained, or two or more types may be contained. Among these, from the viewpoint of expecting a more excellent improvement in the crystallization rate, it is preferable that the diamine unit (X) contains a diamine unit derived from at least one selected from the group consisting of 2-ethyl-1,7-heptanediamine and 2-propyl-1,6-hexanediamine.

[0017] The diamine unit (X) is contained in an amount of 0.1 mol or more and less than 36 mol % of the diamine unit. If it is less than 0.1 mol %, it is difficult to improve the crystallization rate. If it is 36 mol % or more, there is a risk of excessively decreasing heat resistance. From the viewpoint of obtaining a polyamide having an excellent balance between heat resistance and crystallization rate, the diamine unit (X) is preferably 0.5 mol% or more, more preferably 1 mol% or more, even more preferably 3 mol% or more, and still more preferably 5 mol% or more in the diamine units. Also from the above viewpoint, the diamine unit (X) is preferably 35 mol% or less, more preferably 30 mol% or less, even more preferably 25 mol% or less, still more preferably 20 mol% or less, still more preferably 18 mol% or less, still more preferably 15 mol% or less, and still more preferably 10 mol% or less in the diamine units.

[0018] In addition, as one of the preferred embodiments of the present invention, when the diamine unit (X) contains a structural unit derived from at least one diamine selected from the group consisting of 2-ethyl-1,7-heptanediamine and 2-propyl-1,6-hexanediamine, an example of the content of each structural unit is as follows: The content of the structural units derived from 2-ethyl-1,7-heptanediamine in the diamine units is preferably 0.5 mol% or more, more preferably 2 mol% or more, and preferably 20 mol% or less, more preferably 16 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less. The content of the structural units derived from 2-propyl-1,6-hexanediamine in the diamine units is preferably 0.1 mol % or more, more preferably 0.5 mol % or more, and preferably 5 mol % or less, more preferably 2 mol % or less.

[0019] <Other diamine units> The polyamide of this embodiment contains, as diamine units, diamine units other than the diamine units (X) (hereinafter also referred to as "other diamine units"). The other diamine units are preferably structural units derived from diamines having 6 to 10 carbon atoms, more preferably 8 to 10 carbon atoms, and even more preferably 9 carbon atoms, from the viewpoint of smoothly proceeding with the polymerization reaction between dicarboxylic acid and diamine. Examples of other diamine units include structural units derived from at least one diamine selected from the group consisting of linear aliphatic diamines, branched aliphatic diamines other than the aliphatic diamines constituting the diamine unit (X), alicyclic diamines, and aromatic diamines.

[0020] Examples of linear aliphatic diamines include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanediamine, 1,16-hexadecanediamine, 1,17-heptadecanediamine, and 1,18-octadecanediamine.

[0021] Examples of branched aliphatic diamines include 1,2-propanediamine, 1-butyl-1,2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1,4-butanediamine, 1,4-dimethyl-1,4-butanediamine, 2-methyl-1,3-propanediamine, 2-methyl-1,4-butanediamine, 2,3-dimethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, and 3,3-dimethyl-1,6-hexanediamine. Diamines include 2,2-dimethyl-1,6-hexanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, and 5-methyl-1,9-nonanediamine.

[0022] Examples of alicyclic diamines include cyclohexanediamine, methylcyclohexanediamine, norbornanedimethylamine, tricyclodecanedimethyldiamine, bis(4-amino-3-ethylcyclohexyl)methane, and bis(4-amino-3-ethyl-5-methylcyclohexyl)methane.

[0023] Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylether, and 4,4'-methylenedi-2,6-diethylaniline. The constitutional unit derived from the diamine may be of one type only, or of two or more types.

[0024] Among the other diamine units, structural units derived from at least one diamine selected from the group consisting of linear aliphatic diamines and branched aliphatic diamines having methyl groups in the branched chain are more preferred. The content of structural units derived from at least one diamine selected from the group consisting of linear aliphatic diamines and branched aliphatic diamines having methyl groups in the branched chain of the total amount of other diamine units is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, for example, 100 mol%. From the viewpoint of more clearly exhibiting the effects of the present invention, the other diamine units are more preferably structural units derived from at least one diamine selected from the group consisting of 1,6-hexanediamine, 1,9-nonanediamine, 1,10-decanediamine, 2-methyl-1,5-pentanediamine, and 2-methyl-1,8-octanediamine.

[0025] (dicarboxylic acid unit) The dicarboxylic acid unit may include any dicarboxylic acid unit. The dicarboxylic acid unit may include, for example, a constitutional unit derived from at least one dicarboxylic acid selected from the group consisting of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an alicyclic dicarboxylic acid.

[0026] Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, dimethylmalonic acid, 2,2-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, and trimethyladipic acid.

[0027] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, 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, 2,7-naphthalenedicarboxylic acid, 2,3-furandicarboxylic acid, 2,4-furandicarboxylic acid, 2,5-furandicarboxylic acid, and 3,4-furandicarboxylic acid.

[0028] Examples of alicyclic dicarboxylic acids include 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid. The structural unit derived from the dicarboxylic acid may be comprised of only one type, or two or more types.

[0029] From the viewpoint of making it easier to exhibit the effects of the present invention more significantly, the dicarboxylic acid unit preferably contains a structural unit derived from at least one dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids and alicyclic dicarboxylic acids, and more preferably contains a structural unit derived from at least one dicarboxylic acid selected from the group consisting of terephthalic acid, cyclohexanedicarboxylic acid, and naphthalenedicarboxylic acid.

[0030] The molar ratio of diamine units to dicarboxylic acid units in the polyamide [diamine units / dicarboxylic acid units] is preferably 45 / 55 to 55 / 45. When the molar ratio of diamine units to dicarboxylic acid units is within the above range, the polymerization reaction proceeds smoothly, and a polyamide having desired excellent physical properties is easily obtained. The molar ratio of the diamine unit to the dicarboxylic acid unit can be adjusted depending on the compounding ratio (molar ratio) of the raw material diamine to the raw material dicarboxylic acid.

[0031] The total proportion of diamine units and dicarboxylic acid units in the polyamide (the proportion of the total number of moles of dicarboxylic acid units and diamine units to the total number of moles of all structural units constituting the polyamide) is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and may even be 100 mol%. By having the total proportion of diamine units and dicarboxylic acid units in the above range, a polyamide with better desired physical properties can be obtained.

[0032] (aminocarboxylic acid unit) The polyamide may further contain aminocarboxylic acid units in addition to the diamine units and dicarboxylic acid units. Examples of the aminocarboxylic acid unit include structural units derived from lactams such as caprolactam and lauryllactam, and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. The content of the aminocarboxylic acid unit in the polyamide is preferably 40 mol % or less, and more preferably 20 mol % or less, relative to 100 mol % in total of the diamine units and dicarboxylic acid units constituting the polyamide.

[0033] (polycarboxylic acid unit) The polyamide may also contain structural units derived from trivalent or higher polycarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid, to the extent that melt molding is possible, as long as the effects of the present invention are not impaired.

[0034] (End-capping agent unit) The polyamide may contain structural units derived from an end-capping agent (end-capping agent units). The content of the terminal blocking agent units is preferably 1.0 mol% or more, more preferably 2.0 mol% or more, and preferably 10 mol% or less, more preferably 5.0 mol% or less, relative to 100 mol% of the diamine units. When the content of the terminal blocking agent units is within the above range, polyamides with the desired excellent physical properties are readily obtained. The content of the terminal blocking agent units can be adjusted within the above desired range by appropriately adjusting the amount of terminal blocking agent when charging the polymerization raw materials. Taking into consideration the volatilization of the monomer components during polymerization, it is desirable to finely adjust the amount of terminal blocking agent charged so that the desired amount of terminal blocking agent units is incorporated into the resulting polyamide. As a method for determining the content of the end-capping agent units in a polyamide, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-228690, a method is used in which the viscosity of the solution is measured, the total amount of end groups is calculated from the relation between the viscosity and the number average molecular weight, and the amount of amino groups and the amount of carboxyl groups determined by titration are subtracted from the total amount of end groups; 1 Examples of such a method include determining the value based on the integral values ​​of the signals corresponding to the diamine unit and the end-capping agent unit using H-NMR, with the latter being preferred.

[0035] As the terminal blocking agent, a monofunctional compound reactive with a terminal amino group or a terminal carboxyl group can be used. Specific examples include monocarboxylic acids, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, and monoamines. From the viewpoints of reactivity and the stability of the blocked terminals, monocarboxylic acids are preferred as terminal blocking agents for terminal amino groups, and monoamines are preferred as terminal blocking agents for terminal carboxyl groups. From the viewpoints of ease of handling, monocarboxylic acids are more preferred as terminal blocking agents.

[0036] The monocarboxylic acid used as the end-capping agent is not particularly limited as long as it is reactive with an amino group, and examples thereof include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclopentanecarboxylic acid and cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and mixtures thereof. Among these, at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid is preferred from the standpoints of reactivity, stability of the blocked end, cost, and the like.

[0037] The monoamine used as the terminal blocking agent is not particularly limited as long as it is reactive with a carboxyl group, and examples thereof include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine; and any mixtures thereof. Among these, at least one selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline is preferred in terms of reactivity, high boiling point, stability of blocked terminals, and cost.

[0038] (Physical properties of polyamide) The polyamide preferably has a solution viscosity of 0.5 dL / g or more, more preferably 0.7 dL / g or more, and preferably 2.0 dL / g or less, more preferably 1.5 dL / g or less. A solution viscosity within the above range allows the polyamide to have better desired physical properties. The solution viscosity of the polyamide can be determined by measuring the flow time of a solution in concentrated sulfuric acid at a concentration of 0.2 g / dl and a temperature of 30°C. More specifically, it can be determined by the method described in the examples.

[0039] The polyamide preferably has a melting point of 250°C or higher, more preferably 280°C or higher. A melting point within the above range allows the polyamide to have excellent heat resistance. There is no particular upper limit to the melting point of the polyamide, but in consideration of moldability, it is preferably 330°C or lower. The melting point of the polyamide can be determined as the peak temperature of the endothermic peak that appears when the temperature is increased at a rate of 10°C / min using a differential scanning calorimetry (DSC) analyzer, and more specifically, can be determined by the method described in the examples.

[0040] The polyamide preferably has a glass transition temperature of 110°C or higher, more preferably 120°C or higher. Having a glass transition temperature in the above range allows the polyamide to have excellent heat resistance. There is no particular upper limit to the glass transition temperature of the polyamide, but from the viewpoint of handleability, it is preferably 180°C or lower, more preferably 160°C or lower, and may be 150°C or lower. The glass transition temperature of a polyamide can be determined using a differential scanning calorimetry (DSC) analyzer as the temperature of the inflection point that appears when the temperature is increased at a rate of 20°C / min, and more specifically, can be determined by the method described in the examples.

[0041] Polyamide has a crystallization rate of 0.02℃ -1 It is preferable that the temperature is 0.04°C or higher. -1 When the crystallization rate is in the above range, a polyamide with excellent productivity can be obtained. The crystallization rate can be calculated by the following formula (Formula 1). Crystallization rate (℃ -1 ) = 1 / (melting point (°C) - crystallization temperature (°C)) (Equation 1)

[0042] (Polyamide manufacturing method) The polyamide can be produced by any known method for producing polyamide. For example, it can be produced by a melt polymerization method using dicarboxylic acid and diamine as raw materials, a solid-state polymerization method, a melt extrusion polymerization method, etc. Among these, the solid-state polymerization method is preferred from the viewpoint of being able to better suppress thermal degradation during polymerization.

[0043] Polyamides can be produced, for example, by first preparing a nylon salt by adding diamine, dicarboxylic acid, and, if necessary, a catalyst and end-capping agent all at once, followed by heat polymerization at a temperature of 200 to 250°C to form a prepolymer, which is then further solid-state polymerized or polymerized using a melt extruder. When the final stage of polymerization is carried out by solid-state polymerization, it is preferably carried out under reduced pressure or in an inert gas flow. A polymerization temperature within the range of 200 to 280°C results in a high polymerization rate, excellent productivity, and effective suppression of coloration and gelation. When the final stage of polymerization is carried out using a melt extruder, the polymerization temperature is preferably 370°C or less, and polymerization under such conditions results in polyamides with little decomposition and little degradation.

[0044] Catalysts that can be used in producing the polyamide of this embodiment include, for example, phosphoric acid, phosphorous acid, hypophosphorous acid, or salts or esters thereof. Examples of the salts or esters include salts of phosphoric acid, phosphorous acid, or hypophosphorous acid with metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony; ammonium salts of phosphoric acid, phosphorous acid, or hypophosphorous acid; and ethyl esters, isopropyl esters, butyl esters, hexyl esters, isodecyl esters, octadecyl esters, decyl esters, stearyl esters, and phenyl esters of phosphoric acid, phosphorous acid, or hypophosphorous acid.

[0045] The amount of the catalyst used is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and preferably 1.0% by mass or less, more preferably 0.5% by mass or less, based on 100% by mass of the total mass of the raw materials. If the amount of catalyst used is above the lower limit, polymerization proceeds smoothly. If the amount is below the upper limit, impurities derived from the catalyst are less likely to be produced, and defects due to the impurities can be prevented, for example, when the polyamide or a polyamide composition containing it is formed into a film.

[0046] [Polyamide composition] In one embodiment of the present invention, a polyamide composition containing the above polyamide can be provided. The polyamide composition is produced by adding components other than the polyamide to the polyamide. Examples of such components include additives such as inorganic fillers, heat stabilizers, light stabilizers, lubricants, flame retardants, impact modifiers, and colorants. These may be contained alone or in combination of two or more. The content of the additives is not particularly limited as long as it does not impair the effects of the present invention, but can be 0.02 to 200 parts by mass relative to 100 parts by mass of polyamide. Examples of the method for adding the additives include a method of adding them during the polymerization of polyamide, and a method of dry blending them with polyamide and then melt-kneading them.

[0047] (Method of producing polyamide composition) The method for producing the polyamide composition is not particularly limited, and any method capable of uniformly mixing the polyamide and the above-mentioned additives can be preferably employed. The mixing is usually preferably performed by melt-kneading using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or the like. The melt-kneading conditions are not particularly limited, and examples include melt-kneading for about 1 to 30 minutes at a temperature range about 10 to 50°C higher than the melting point of the polyamide.

[0048] [Molded body] In one embodiment of the present invention, a molded article can be made of the polyamide or the polyamide composition. The molded article of this embodiment can be used as an electric part, an electronic part, an automobile part, an industrial part, a fiber, a film, a sheet, a household product, or any other molded article of any shape and for any purpose.

[0049] Examples of electrical and electronic components include connectors such as FPC connectors, BtoB connectors, card connectors, SMT connectors (coaxial connectors, etc.), and memory card connectors; SMT relays; SMT bobbins; sockets such as memory sockets and CPU sockets; switches such as command switches and SMT switches; optical components such as optical fiber components and optical sensors; LED application components such as LED reflectors; and electronic substrates such as solar cell substrates, LED mounting substrates, flexible printed wiring boards, and resin molded circuit boards.

[0050] Automotive parts include, for example, cooling parts such as thermostat housings, radiator tanks, radiator hoses, water outlets, water pump housings, and rear joints; intake and exhaust system parts such as intercooler tanks, intercooler cases, turbo duct pipes, EGR cooler cases, resonators, throttle bodies, intake manifolds, and tailpipes; fuel system parts such as fuel delivery pipes, gasoline tanks, quick connectors, canisters, pump modules, fuel pipes, oil strainers, lock nuts, and seals; structural parts such as mount brackets, torque rods, and cylinder head covers; bearing retainers, gear tensioners, headlamp actuator gears, and sliding doors. These include drive system parts such as rollers and peripheral clutch parts; brake system parts such as air brake tubes; automotive electrical parts such as wire harness connectors in the engine bay, motor parts, sensors, ABS bobbins, combination switches, and on-board switches; and interior and exterior parts such as sliding door dampers, door mirror stays, door mirror brackets, inner mirror stays, roof rails, engine mount brackets, air cleaner inlet pipes, door checkers, plastic chains, emblems, clips, breaker covers, cup holders, airbags, fenders, spoilers, radiator supports, radiator grilles, louvers, air scoops, hood bulges, tailgates, and fuel sender modules.

[0051] Examples of industrial parts include gas pipes, oil field drilling pipes, hoses, anti-termite cables (communication cables, pass cables, etc.), paint parts of powder coated products (inner coatings of water pipes, etc.), undersea oil field pipes, pressure-resistant hoses, hydraulic tubes, paint tubes, fuel pumps, separators, supercharger ducts, butterfly valves, conveyor roller bearings, railway sleeper spring supports, outboard motor engine covers, generator engine covers, irrigation valves, large switches, and monofilaments (extruded threads) for fishing nets, etc.

[0052] Examples of fibers include airbag base fabrics, heat-resistant filters, reinforcing fibers, brush bristles, fishing lines, tire cords, artificial turf, carpets, and seat fabrics.

[0053] Examples of films and sheets include heat-resistant adhesive tapes such as heat-resistant masking tape and industrial tape; magnetic tape materials such as cassette tapes, magnetic tapes for storing data in digital data storage, and video tapes; food packaging materials such as pouches for retort foods, individual packaging for sweets, and packaging for processed meat products; and electronic component packaging materials such as packaging for semiconductor packages.

[0054] In particular, the polyamide of this embodiment has an excellent crystallization rate and is therefore suitable for use in electrical and electronic components that require the production of a large number of components in a short period of time. Specifically, it can be used in electrical and electronic components that involve SMT processes, more specifically, SMT-compatible connectors, SMT relays, SMT bobbins, sockets, command switches, SMT switches, etc. [Example]

[0055] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0056] The evaluations in the examples and comparative examples were carried out according to the methods shown below.

[0057] ·Solution viscosity For the polyamides obtained in the Examples and Comparative Examples, the solution viscosity (dl / g) at a temperature of 30°C and a concentration of 0.2 g / dl was calculated using concentrated sulfuric acid as a solvent according to the following formula. η=[ln(t1 / t0)] / c In the above formula, η represents the solution viscosity (dl / g), t0 represents the flow time (seconds) of the solvent (concentrated sulfuric acid), t1 represents the flow time (seconds) of the sample solution, and c represents the concentration (g / dl) of the sample in the sample solution (i.e., 0.2 g / dl).

[0058] Melting point, crystallization temperature, glass transition temperature The melting point, crystallization temperature, and glass transition temperature of the polyamides obtained in the examples and comparative examples were measured using a differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Corporation. The melting point and crystallization temperature were measured in accordance with ISO 11357-3 (2011, 2nd edition). Specifically, in a nitrogen atmosphere, a sample (polyamide) was heated from 30°C to 340°C at a rate of 10°C / min, held at 340°C for 5 minutes to completely melt the sample, then cooled to 50°C at a rate of 10°C / min, held at 50°C for 5 minutes, and then heated again to 340°C at a rate of 10°C / min. The peak temperature of the exothermic peak that appeared when the temperature was lowered was taken as the crystallization temperature, and the peak temperature of the endothermic peak that appeared when the temperature was raised again was taken as the melting point (°C). The glass transition temperature (°C) was measured in accordance with ISO 11357-2 (2013, 2nd edition). Specifically, in a nitrogen atmosphere, a sample (polyamide) was heated from 30°C to 340°C at a rate of 20°C / min, held at 340°C for 5 minutes to completely melt the sample, then cooled to 50°C at a rate of 20°C / min and held at 50°C for 5 minutes. The temperature at the inflection point that appeared when the sample was again heated to 200°C at a rate of 20°C / min was taken as the glass transition temperature (°C).

[0059] ·Crystallization speed The crystallization rates of the polyamides obtained in the examples and comparative examples were calculated using the following formula (Formula 1). Crystallization rate (℃ -1 ) = 1 / (melting point (°C) - crystallization temperature (°C)) (Equation 1) In the formula (1), the "melting point (°C)" and the "crystallization temperature (°C)" are measured values ​​according to the above-mentioned method. In addition, in Table 1, the unit of the crystallization rate is "°C". -1 " is written as "1 / ℃", which is synonymous with ".

[0060] [Example 1] 16.4 g of terephthalic acid, 15.9 g of a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, and 2-methyl-1,8-octanediamine [4 / 1 / 95 (molar ratio)], 0.37 g of benzoic acid, 0.03 g of sodium hypophosphite monohydrate (0.1% by mass based on the total mass of the raw materials), and 12.7 mL of distilled water were placed in a 100 mL autoclave and purged with nitrogen. After stirring at 150°C for 30 minutes, the temperature inside the autoclave was raised to 250°C. Heating was continued for 1 hour while maintaining the temperature at 250°C, and water vapor was gradually removed to allow the reaction. After the required amount of water vapor was distilled off, the reaction was continued for another 1 hour to obtain a prepolymer. The resulting prepolymer was crushed to a particle size of 1 mm or less and dried at 120°C under reduced pressure for 12 hours. This was subjected to solid-state polymerization at 240°C and 90 Pa or less to obtain a polyamide having a melting point of 282°C.

[0061] [Example 2] A polyamide having a melting point of 283°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, and 2-methyl-1,8-octanediamine [5.6 / 0.4 / 94 (molar ratio)].

[0062] [Example 3] A polyamide having a melting point of 262°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, and 2-methyl-1,8-octanediamine [12 / 3 / 85 (molar ratio)].

[0063] [Example 4] A polyamide having a melting point of 258°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, and 2-methyl-1,8-octanediamine [16 / 4 / 80 (molar ratio)].

[0064] [Example 5] A polyamide having a melting point of 288°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine and 1,9-nonanediamine [4 / 1 / 20 / 75 (molar ratio)].

[0065] [Example 6] A polyamide having a melting point of 307°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, and 1,9-nonanediamine [0.5 / 14.5 / 85 (molar ratio)].

[0066] [Comparative Example 1] A polyamide having a melting point of 285°C was obtained in the same manner as in Example 1, except that the diamine unit was changed to 2-methyl-1,8-octanediamine.

[0067] Comparative Example 2 A polyamide having a melting point of 306°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-methyl-1,8-octanediamine and 1,9-nonanediamine [15 / 85 (molar ratio)].

[0068] [Example 7] A polyamide having a melting point of 283°C was obtained in the same manner as in Example 1, except that the dicarboxylic acid units were 21.3 g of naphthalenedicarboxylic acid and the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine and 1,9-nonanediamine [4 / 1 / 20 / 75 (molar ratio)].

[0069] Comparative Example 3 A polyamide having a melting point of 294°C was obtained in the same manner as in Example 1, except that the dicarboxylic acid unit was 21.3 g of naphthalenedicarboxylic acid and the diamine unit was a mixture of 2-methyl-1,8-octanediamine and 1,9-nonanediamine [15 / 85 (molar ratio)].

[0070] [Example 8] A polyamide having a melting point of 292°C was obtained in the same manner as in Example 1, except that the dicarboxylic acid units were 17.0 g of cyclohexanedicarboxylic acid (cis / trans = 79.9 / 20.1) and the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine and 1,9-nonanediamine [4 / 1 / 20 / 75 (molar ratio)].

[0071] Comparative Example 4 A polyamide having a melting point of 301°C was obtained in the same manner as in Example 1, except that the dicarboxylic acid units were 17.0 g of cyclohexanedicarboxylic acid (cis / trans = 79.9 / 20.1) and the diamine units were a mixture of 2-methyl-1,8-octanediamine and 1,9-nonanediamine [15 / 85 (molar ratio)].

[0072] [Example 9] A polyamide having a melting point of 289°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-ethyl-1,7-heptanediamine, 2-propyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine and 1,10-decanediamine [4 / 1 / 20 / 75 (molar ratio)].

[0073] Comparative Example 5 A polyamide having a melting point of 301°C was obtained in the same manner as in Example 1, except that the diamine units were a mixture of 2-methyl-1,8-octanediamine and 1,10-decanediamine [20 / 80 (molar ratio)].

[0074] Table 1 shows the compositions of the examples and comparative examples and the measurement results thereof.

[0075] [Table 1]

[0076] The abbreviations for the compounds used in Table 1 above and the details of those compounds are as shown in Table 2 below. In addition, "(EHDA+PHDA)" in Table 1 represents the total amount (mol%) of EHDA and PHDA in the diamine unit.

[0077] [Table 2]

[0078] Table 1 shows that the crystallization rate of the Examples is faster when comparing Examples 1 to 6 with Comparative Examples 1 and 2, Example 7 with Comparative Example 3, Example 8 with Comparative Example 4, and Example 9 with Comparative Example 5. That is, in polyamides containing the same dicarboxylic acid units, if the diamine units contain 2-ethyl-1,7-heptanediamine units and 2-propyl-1,6-hexanediamine units, the polyamide will have a faster crystallization rate and be superior in productivity. Furthermore, compared to Comparative Examples 2 to 5, which contain only 2-methyl-1,8-octanediamine units, whose branched structure is a methyl group, as branched aliphatic diamine units, the Examples contain 2-ethyl-1,7-heptanediamine units and 2-propyl-1,6-hexanediamine units, but the melting point and glass transition temperature do not decrease much, and the heat resistance is excellent. Therefore, it can be seen from Table 1 that the polyamides of the examples have an improved crystallization rate while maintaining excellent heat resistance, and are excellent in both crystallization rate and heat resistance. [Industrial Applicability]

[0079] As described above, the polyamide of the present invention can achieve both excellent heat resistance and high crystallization rate, which has been difficult to achieve until now. Therefore, the polyamide of the present invention can be used for various molded articles that require heat resistance, and can improve productivity in producing molded articles, making it very useful.

Claims

1. 1. A polyamide comprising diamine units and dicarboxylic acid units, The diamine units contain diamine units (X) in an amount of 0.1 mol% or more and less than 36 mol%, the diamine unit (X) is a diamine unit derived from an aliphatic diamine having 6 to 10 carbon atoms and, when the carbon atom to which any one amino group is bonded is the 1st position, an alkyl group having 2 or 3 carbon atoms is bonded to the 2nd position carbon atom, the diamine unit (X) contains a diamine unit derived from at least one selected from the group consisting of 2-ethyl-1,7-heptanediamine and 2-propyl-1,6-hexanediamine; polyamide.

2. 2. The polyamide according to claim 1, wherein the diamine units contain 0.1 to 25 mol % of the diamine unit (X).

3. 3. The polyamide according to claim 1, wherein the diamine units contain 1 to 10 mol% of the diamine unit (X).

4. The polyamide according to any one of claims 1 to 3, wherein the diamine unit comprises a diamine unit other than the diamine unit (X), and the diamine unit other than the diamine unit (X) is a diamine unit derived from at least one selected from the group consisting of a linear aliphatic diamine, a branched aliphatic diamine other than the aliphatic diamine constituting the diamine unit (X), an alicyclic diamine, and an aromatic diamine.

5. The polyamide according to any one of claims 1 to 4, wherein the polyamide contains, as the diamine units, diamine units other than the diamine unit (X), and the diamine units other than the diamine unit (X) are diamine units derived from at least one selected from the group consisting of linear aliphatic diamines and branched aliphatic diamines whose branched chains are methyl groups.

6. The polyamide according to any one of claims 1 to 5, wherein the polyamide contains, as the diamine units, diamine units other than the diamine unit (X), and the diamine units other than the diamine unit (X) are diamine units derived from a diamine having 6 to 10 carbon atoms.

7. The polyamide according to claim 1, wherein the polyamide contains, as the diamine unit, a diamine unit other than the diamine unit (X), and the diamine unit other than the diamine unit (X) is a diamine unit derived from at least one selected from the group consisting of 1,6-hexanediamine, 1,9-nonanediamine, 1,10-decanediamine, 2-methyl-1,5-pentanediamine, and 2-methyl-1,8-octanediamine.

8. The polyamide according to any one of claims 1 to 7, wherein the dicarboxylic acid units comprise dicarboxylic acid units derived from at least one selected from the group consisting of aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and alicyclic dicarboxylic acids.

9. The polyamide according to any one of claims 1 to 8, wherein the dicarboxylic acid units comprise dicarboxylic acid units derived from at least one selected from the group consisting of terephthalic acid, cyclohexanedicarboxylic acid, and naphthalenedicarboxylic acid.

10. A polyamide composition comprising the polyamide according to any one of claims 1 to 9.

11. A molded article comprising the polyamide according to any one of claims 1 to 9 or the polyamide composition according to claim 10.

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