JP5598052B2 - Polyamide resin composition excellent in low-temperature impact resistance and molded product thereof - Google Patents

Description

  The present invention relates to a polyamide resin composition having excellent low-temperature impact properties and a molded article formed by injection molding or extrusion molding a polyamide resin composition having excellent low-temperature impact properties.

  Polyamide resin has excellent mechanical properties such as moldability, chemical resistance, tensile strength, bending strength, and wear resistance, and is used in a wide range of fields such as electrical / electronic parts, mechanical parts, and automotive parts. However, the disadvantage is that the impact resistance is slightly low and the low temperature impact resistance is particularly poor.

Therefore, conventionally, in order to improve the impact resistance of the polyamide resin, a modified elastomer is blended with the polyamide resin (for example, Patent Documents 1 and 2).
Conventionally, general polyamide resins such as polyamide 6 and polyamide 66 have been used for the polyamide resins of these modified elastomer-containing polyamide resin compositions, and there is no example in which the polyamide 5X used in the present invention is used.

Japanese Patent No. 4018139 JP 62-59653 A

  By blending the modified elastomer, the impact resistance of the polyamide resin composition is improved, but the bending elastic modulus is impaired. That is, the modified elastomer can obtain a more excellent impact resistance improvement effect by increasing its blending amount, but the flexural modulus tends to decrease as the blending amount of the modified elastomer increases.

  The present invention provides a polyamide resin composition that can obtain a high low temperature impact improvement effect with a small amount of a modified elastomer, and therefore has an improved low temperature impact property while suppressing a decrease in flexural modulus. Objective.

  As a result of intensive studies to solve the above problems, the present inventors have effectively used the polyamide 5X as a polyamide resin for blending the modified elastomer, so that the effect of improving the impact resistance by the modified elastomer is effectively exhibited, and there is little modification. It has been found that a polyamide resin composition having excellent low-temperature impact properties can be obtained with a blending amount of the elastomer and thus without lowering the flexural modulus.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] As the polymer component, 90 to 50% by weight of the following component (A) and 10 to 50% by weight of the component (B) composed of the following component (B-1) and / or the following component (B-2) are included. A polyamide resin composition, the following polyamide 5X has two endothermic peaks as measured by differential scanning calorimetry, and the temperature difference between the peak tops of the two endothermic peaks is 10 to 50 ° C. A polyamide resin composition having excellent low-temperature impact properties, wherein the 5X terminal amino group concentration is 16 to 100 µeq / g .
Component (A): a polyamide resin having a structure corresponding to a polycondensate obtained by a polycondensation reaction using a diamine containing pentamethylenediamine and a dicarboxylic acid as monomer components (hereinafter, this polyamide resin is referred to as “polyamide 5X”). Called.)
Component (B-1): formed by graft polymerization of an α, β-unsaturated carboxylic acid and / or a derivative thereof onto an olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 or more carbon atoms. Modified Polyolefin Copolymer (B-2) Component: An α, β-unsaturated carboxylic acid is added to a hydrogenated block copolymer containing a vinyl aromatic compound polymer block a and a conjugated diene compound polymer block b. Modified block copolymer obtained by graft polymerization of acid and / or derivative thereof

[2] In [1], the component (A) forms a continuous phase, and the 50-point average particle size of the dispersed phase comprising the component (B) in the component (A) is 1 to 3 μm. A polyamide resin composition having excellent low-temperature impact properties.

[3] Oite to [1] or [2], wherein the polyamide 5X, characterized in that polyamide 56, polyamide 59, polyamide 510, is at least one selected from the group consisting of polyamide 512 and 56/6 A polyamide resin composition having excellent low-temperature impact properties.

[ 4 ] In any one of [1] to [ 3 ], the olefin copolymer in the component (B-1) is an ethylene-butene copolymer and / or an ethylene-propylene copolymer. A polyamide resin composition having excellent low-temperature impact properties.

[ 5 ] In any one of [1] to [ 4 ], the hydrogenated block copolymer in the component (B-2) is a styrene-ethylene-butylene-styrene copolymer. A polyamide resin composition having excellent impact properties.

[ 6 ] In any one of [1] to [ 5 ], the α, β-unsaturated carboxylic acid is maleic anhydride, and the polyamide resin composition having excellent low-temperature impact properties.

[ 7 ] In any one of [1] to [ 6 ], a polyamide resin composition excellent in low-temperature impact property, wherein the Charpy impact value with notch measured at −30 ° C. is 70 kJ / m ² or more.

[ 8 ] An injection-molded product obtained by injection-molding the polyamide resin composition having excellent low-temperature impact properties according to any one of [1] to [ 7 ].

[ 9 ] An extruded product obtained by extruding the polyamide resin composition having excellent low-temperature impact properties according to any one of [1] to [ 7 ].

[ 10 ] An automobile / railway vehicle component or an electric / electronic / OA component, characterized in that at least a part thereof is formed of the molded product according to [ 8 ] or [ 9 ].

  According to the polyamide resin composition of the present invention obtained by blending a specific modified elastomer with polyamide 5X as a polyamide resin, the effect of improving the impact resistance by the modified elastomer is effectively exhibited, and with a small amount of the modified elastomer, Therefore, it is possible to obtain a polyamide resin composition having excellent low-temperature impact properties without reducing the bending elastic modulus.

The action mechanism that exhibits such excellent effects according to the present invention is considered as follows.
That is, the polyamide 5X used as the component (A) in the present invention is grafted to the amino group of the polyamide resin and the modified elastomer as compared with polyamide 6 and polyamide 66, which are polyamide resins used in the conventional polyamide resin composition. High reactivity with substituents derived from polymerized unsaturated carboxylic acids and / or derivatives thereof, and excellent bondability between polyamide resin and modified elastomer, polyamide resin and modified elastomer when impacted Interfacial peeling is reduced, and excellent low-temperature impact properties are obtained.

In particular, in the polyamide 5X having two endothermic peaks as measured by the DSC method, an excellent effect of improving low temperature impact properties can be obtained by the following mechanism.
When the force is dispersed twice, the residual stress of the modified elastomer in the solidified polyamide resin becomes small, and as a result, the particle size of the dispersed phase of the modified elastomer becomes large. A modified elastomer having a large dispersed particle size and a small residual stress has a great effect of effectively stopping crazes generated in a continuous phase when an impact is applied even at a low temperature of, for example, -30 ° C. As a result, excellent low-temperature impact properties can be obtained.
That is, in a polymer alloy in which a modified elastomer forms a dispersed phase in a continuous phase formed of a polyamide resin, the polyamide resin is first crystallized in the solidification process from the time of melting. In this process, the modified elastomer is removed from the crystal part of the polyamide resin, and is fixed in the continuous phase of the amorphous part of the polyamide resin while receiving the compressive stress.
Here, when the polyamide resin constituting the continuous phase has two endothermic peaks, in the solidification process from the time of melting, crystals are first generated at the endothermic peak temperature on the high temperature side of the polyamide resin, and then the endothermic peak on the low temperature side. Since crystals are formed at a temperature, the modified elastomer in the dispersed phase is temporarily relieved between the crystallization on the high temperature side and the crystallization on the low temperature side, and is again subjected to compressive stress in the subsequent crystallization on the low temperature side. Thus, in the solidification process from the time of melting, the stress applied to the modified elastomer is dispersed twice, and the polyamide resin solidified by stress relaxation that occurs between crystallization on the high temperature side and crystallization on the low temperature side. The residual stress of the modified elastomer is small. Further, since it is affected by the crystallization of the polyamide resin twice as described above, the particle diameter of the dispersed phase of the modified elastomer tends to be larger than that of conventional polyamide resins such as polyamide 6 and polyamide 66. Such a modified elastomer with a large dispersed particle size and low residual stress, for example, effectively stops crazing generated in the continuous phase when an impact is applied even at a low temperature of −30 ° C. Is big. As a result, excellent low-temperature impact properties can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[(A) component]
The component (A) according to the present invention is a polyamide 5X, that is, a polyamide resin having a structure corresponding to a polycondensate obtained by a polycondensation reaction using a diamine containing pentamethylenediamine and a dicarboxylic acid as monomer components. is there.

  The diamine used in the polyamide 5X contains pentamethylenediamine as an essential component, but other examples include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, and 1,7-diamino. Heptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane 1,15-diaminopentadecane, 1,16-diaminohexadecane, 1,17-diaminoheptadecane, 1,18-diaminooctadecane, 1,19-diaminononadecane, 1,20-diaminoeicosane, 2-methyl- Aliphatic diamines such as 1,5-diaminopentane; It may contain one or more of such aromatic diamines such as xylylenediamine; alicyclic diamines such Njiamin.

  On the other hand, dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, tetradecanedioic acid, pentadecanedioic acid. 1 type or 2 types or more, such as aliphatic dicarboxylic acid, such as acid and octadecanedioic acid; Cycloaliphatic dicarboxylic acid, such as cyclohexane dicarboxylic acid; Aromatic dicarboxylic acid, such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene dicarboxylic acid Can be mentioned. Other monomer components include, for example, amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and paraaminomethylbenzoic acid; one kind of lactam such as ε-caprolactam and ω-laurolactam or the like Two or more kinds may be included.

  In the present invention, the polyamide 5X as the component (A) preferably has two endothermic peaks measured as melting points by DSC (differential scanning calorimetry), and the temperature difference between the peak tops of the two endothermic peaks is It is preferable that it is 5-50 degreeC, especially 10-45 degreeC. Moreover, when it has two endothermic peaks, the temperature at the peak top of each endothermic peak is preferably 180 to 280 ° C on the high temperature side, more preferably 200 to 270 ° C, and preferably 150 to 250 ° C on the low temperature side. Preferably it is 160-250 degreeC. In the present invention, the endothermic peak is an endothermic peak observed when the sample is heated and melted once to remove the influence of the thermal history on the crystallinity and then heated again. Specifically, in the case of polyamide 56, for example, it can be determined in the following manner. The temperature is raised from 30 to 300 ° C. at a rate of 20 ° C./min, and the sample held at 300 ° C. for 3 minutes is completely dissolved, and then the temperature is lowered to 30 ° C. at a rate of 20 ° C./min. Subsequently, after holding at 30 ° C. for 3 minutes, the temperature is raised to 300 ° C. at a rate of 20 ° C./min, and the temperature at the peak top of the endothermic peak observed at the time of temperature rise is obtained. The maximum temperature at the time of temperature rise may be appropriately adjusted according to the expected peak top temperature of the endothermic peak of the resin. Usually, the peak top temperature of the endothermic peak (when two or more endothermic peaks exist, The temperature may be selected in the range of the peak top temperature of the endothermic peak on the high temperature side) + 50 ° C.

  The presence of two endothermic peaks by the DSC method means that crystallization during molding proceeds in two stages, and as described above, the crystallization proceeds in two stages. Due to the stress relaxation effect of the modified elastomer, an excellent impact resistance improvement effect can be obtained.

  However, if the peak top temperature difference of the endothermic peak is excessively small, the effect of the above two-stage crystallization cannot be sufficiently obtained. If excessively large, the moldability may be impaired. The peak top temperature difference between the two endothermic peaks is preferably 5 to 50 ° C., more preferably 10 to 45 ° C.

  The terminal amino group concentration of the polyamide 5X used in the present invention is preferably 16 to 100 μeq / g, more preferably 20 to 90 μeq / g, and particularly preferably 25 to 80 μeq / g. If the terminal amino group concentration of the polyamide 5X is too low, the reactivity with the modified elastomer of the component (B) is poor, and therefore the impact resistance improving effect due to the blending of the modified elastomer cannot be sufficiently obtained, If it is too high, a gel may be formed, which is not preferable.

  The terminal amino group concentration of polyamide 5X is measured by the method described in the Examples section below.

Further, the molecular weight of the polyamide 5X used in the present invention is not particularly limited and is appropriately selected depending on the purpose. From the viewpoint of practicality, a solution dissolved in 98% sulfuric acid at 25 ° C. (concentration of polyamide 5X: 0) 0.01 g / ml) relative viscosity (η _r ), usually 1.5 to 5.5, preferably 1.6 to 3.5, more preferably 1.8 to 3, particularly preferably 2 to 2.8. Range.

In the present invention, by using polyamide 5X as the polyamide resin, high impact resistance is expressed with a small amount of the modified elastomer. This is considered to be due to the difference in crystal form of the polyamide resin, and is estimated as follows.
That is, the polyamide 5X tends to have a γ-type crystal, but the conventionally used polyamide 6 and polyamide 66 have a tendency to have only an α-type crystal. Since the α-type crystal has a higher elastic modulus than the γ-type crystal, the impact resistance tends to be difficult to improve. Since the polyamide 5X having γ-type crystals does not have the above-described problems, it is considered that the effect of developing impact resistance by the blending of the modified elastomer is enhanced.
Further, when the polyamide resin constituting the continuous phase has two endothermic peaks, as described above, the stress applied to the modified elastomer is dispersed twice during the solidification process from the time of melting, thereby reducing the residual stress. It is considered that a dispersed phase dispersed in an appropriate particle size is formed, and the impact resistance is further improved. From the above, it is particularly preferable to use polyamide 56, polyamide 59, polyamide 510, polyamide 512, and 56/6 as the polyamide 5X.

  In addition, polyamide 5X may be used individually by 1 type, and 2 or more types of things from which a composition, molecular weight, a terminal amino group concentration, etc. differ may be mixed and used for arbitrary combinations and ratios.

[Component (B)]
The component (B) used in the present invention is a modified elastomer composed of either one of the following components (B-1) and (B-2) or a mixture of both.

Component (B-1): formed by graft polymerization of an α, β-unsaturated carboxylic acid and / or a derivative thereof onto an olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 or more carbon atoms. Modified Polyolefin Copolymer (B-2) Component: An α, β-unsaturated carboxylic acid is added to a hydrogenated block copolymer containing a vinyl aromatic compound polymer block a and a conjugated diene compound polymer block b. Modified block copolymer obtained by graft polymerization of acid and / or derivative thereof

  Here, the derivative of α, β-unsaturated carboxylic acid is a derivative in a broad sense including an acid anhydride of α, β-unsaturated carboxylic acid. Hereinafter, the α, β-unsaturated carboxylic acid and / or its derivative is referred to as “α, β-unsaturated carboxylic acid”.

<(B-1) component>
The component (B-1) is a modified polyolefin system obtained by graft polymerization of an α, β-unsaturated carboxylic acid to an olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 or more carbon atoms. It is a copolymer.

  In the olefin copolymer, the α-olefin to be copolymerized with ethylene is preferably one having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 3- Examples include methylbutene-1, 4-methylpentene-1, and two or more of these may be used in combination. Among these, a linear α-olefin having 3 to 10 carbon atoms is preferable, propylene and 1-butene are more preferable, and propylene is particularly preferable.

  Examples of the olefin copolymer include ethylene-propylene copolymer (EPR) and ethylene-butene copolymer (EBR).

  The melt volume rate (MVR) of the olefin copolymer is preferably 0.1 to 400 g / 10 minutes, and more preferably 0.2 to 200 g / 10 minutes. The MVR in the present invention is a value measured at a temperature of 180 ° C. and a load of 21.17 N in accordance with JIS K7210 standard.

  The α, β-unsaturated carboxylic acids to be graft-polymerized on the olefin copolymer include (anhydrous) maleic acid, (anhydrous) itaconic acid, chloro (anhydrous) maleic acid, (anhydrous) citraconic acid, and butenyl (anhydrous). Examples thereof include succinic acid, tetrahydro (anhydride) phthalic acid, and these acid halides, amides, imides, alkyl esters having 1 to 20 carbon atoms, or glycol esters, specifically maleimide, monomethyl maleate, dimethyl maleate. Etc. Here, “(anhydrous)” indicates anhydrous unsaturated carboxylic acid or unsaturated carboxylic acid. Among these, α, β-unsaturated carboxylic acids or acid anhydrides thereof are preferable, and (anhydrous) maleic acid or (anhydrous) itaconic acid, particularly maleic anhydride is more preferable. Two or more of these may be used in combination.

  The graft polymerization amount of α, β-unsaturated carboxylic acids to the olefin copolymer is preferably 0.05 to 5 weights as the amount of α, β-unsaturated carboxylic acids relative to 100 parts by weight of the olefin copolymer. Parts, more preferably 0.1 to 3 parts by weight. By making this graft polymerization amount 0.05 parts by weight or more, impact resistance tends to be improved, which is preferable. Further, when the graft polymerization amount is 5 parts by weight or less, the fluidity at the time of molding is improved and the molding of a thin molded product tends to be facilitated. The graft polymerization amount of α, β-unsaturated carboxylic acids to the olefin copolymer can be changed by changing the amount of α, β-unsaturated carboxylic acids charged to the olefin copolymer during the production of the modified polyolefin copolymer. Can be adjusted.

  In the graft polymerization reaction, a radical generator may be blended together with α, β-unsaturated carboxylic acids. Examples of the radical generator include organic peroxides and azo compounds.

  Specific examples of the organic peroxide include, for example, tert-butyl hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethyl Hydroperoxides such as butyl hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, di-tert- Dialkyl peroxides such as butyl peroxide, tert-butyl cumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, dicumyl peroxide, 2,2-bis-tert- Butyl peroxybutane, 2,2-bis Peroxyketals such as tert-butylperoxyoctane, 1,1-bis-tert-butylperoxycyclohexane, 1,1-bis-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert -Butyl peroxyisophthalate, tert-butyl peroxybenzoate, tert-butyl peroxyacetate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (Benzoylperoxy) peroxyesters such as hexyne-3, tert-butylperoxyisopropyl carbonate, tert-butylperoxyisobutyrate, benzoyl peroxide, m-toluoyl peroxide, acetyl peroxide, lauroyl peroxide Diacyl peroxides such as id and the like.

  Specific examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 1-[(1-cyano-1-methylethyl) azo] formamide, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2′-azobis (2,4,4-trimethylpentane), 2,2′-azobis (2-methylpropane) and the like.

  Among these radical generators, a radical generator having a half-life temperature of 10 hours or less, preferably 190 ° C. or lower, more preferably 120 ° C. or higher, is particularly preferable from the viewpoint of dimensional stability and impact resistance. Among those exemplified above, benzoyl peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, tert-butylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2, 5-Dimethyl-2,5-di (benzoylperoxy) hexyne-3 is particularly preferred.

  The amount of the radical generator used is preferably in the range of 0.01 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and 0.01 to 1 part by weight with respect to 100 parts by weight of the olefin copolymer. More preferred. By making the amount of the radical generator used 0.01 parts by weight or more, a sufficient graft polymerization amount is obtained by the olefin copolymer, and by making it 10 parts by weight or less, the molecular weight of the olefin copolymer is increased. It tends to be easy to manufacture without becoming too small. The radical generator can be dissolved and mixed in an organic solvent or the like. Moreover, what mix | blended inorganic fillers, such as a calcium carbonate, a talc, and a silica, may be used.

(B-1) The modified polyolefin copolymer can be prepared by a conventionally known method as a method for changing the olefin copolymer to reactivity.
For example, it can be produced by a method in which a predetermined amount of an olefin copolymer, α, β-unsaturated carboxylic acid, radical generator and the like are weighed and uniformly mixed, and then melt-kneaded.

  Examples of the mixing device include a tumbler blender, a ribbon blender, a V-type blender, and a Henschel mixer. Examples of the melt kneading device include a mixing roll, a kneader, a Banbury mixer, a Brabender plastograph, and a single or twin screw extruder. It is done. The melt kneading temperature depends on the half-life temperature of the radical generator, but is usually selected in the range of 120 to 300 ° C, preferably in the range of 150 to 280 ° C. The kneading time depends on the kneading temperature, the type of radical generator, the amount added, etc., but is usually 0.1 to 30 minutes, preferably 0.5 to 10 minutes.

  (B-1) As the modified polyolefin copolymer, maleic anhydride graft polymerization ethylene-propylene copolymer (maleic anhydride modified EPR), maleic anhydride graft polymerization ethylene-butene copolymer (maleic anhydride modified EBR). ) Is preferable because the mechanical strength and toughness can be satisfied in a well-balanced manner.

<B-2 component>
Component (B-2) is a graft polymerization of α, β-unsaturated carboxylic acids to a hydrogenated block copolymer containing vinyl aromatic compound polymer block a and conjugated diene compound polymer block b. This is a modified block copolymer.

  The hydrogenated product of the block copolymer is a block copolymer of a vinyl aromatic compound polymer block a and a conjugated diene compound polymer block b, and the aliphatic unsaturated group of the block b by hydrogenation. Means a reduced block copolymer. The arrangement structure of the block a and the block b may be any structure such as a linear structure or a branched structure. Moreover, among these structures, a random chain derived from a random copolymer portion of a vinyl aromatic compound and a conjugated diene compound may be included in part. Among these structures, a linear structure is preferable, and an aba triblock structure is more preferable. The abb type block copolymer may contain an ab type diblock structure. Two or more hydrogenated products of these block copolymers may be used in combination.

  As a vinyl aromatic compound which comprises the vinyl aromatic compound polymer block a, Preferably, styrene, (alpha) -methylstyrene, vinyl toluene, vinyl xylene, etc. are mentioned, More preferably, it is styrene. The conjugated diene compound constituting the conjugated diene compound block b is preferably 1,3-butadiene or 2-methyl-1,3-butadiene.

  The proportion of the repeating unit derived from the vinyl aromatic compound in the hydrogenated block copolymer is preferably in the range of 10 to 70% by mole, more preferably in the range of 10 to 40% by mole, based on the total repeating units. The range of 15-25 mol% is more preferable. By making this ratio 10 mol% or more, the thermal stability tends to be improved, and is less susceptible to oxidative degradation during the production and molding of the resin composition. Moreover, it exists in the tendency for impact resistance to improve by setting it as 70 mol% or less. In addition, the proportion of unsaturated bonds derived from the conjugated diene compound and remaining without hydrogenation in the aliphatic chain portion in the block copolymer is preferably 20% or less of all bonds in the molecule. 10% or less is more preferable. The aromatic unsaturated bond derived from the vinyl aromatic compound may be hydrogenated, but the ratio of the hydrogenated aromatic unsaturated bond is 25% or less of all the bonds in the molecule. It is preferable. As a hydrogenated product of such a block copolymer, a conjugated diene compound that is a monomer constituting the conjugated diene compound polymer block b is 1,3-butadiene, styrene-ethylene-butylene-styrene. Various aba type triblock structures such as copolymers (SEBS) and styrene-ethylene-propylene-styrene copolymers (SEPS) in which the conjugated diene compound is 2-methyl-1,3-butadiene Are commercially available and are readily available. Among these, it is particularly preferable to use SEBS because of its excellent melting heat stability.

  The number average molecular weight of the hydrogenated product of these block copolymers is preferably in the range of 50,000 to 180,000. By making the number average molecular weight 50,000 or more, the impact resistance and dimensional stability of the finally obtained resin composition are excellent, and further, the appearance of the molded product obtained from the resin composition is made good. Can do. Further, it is preferable that the number average molecular weight is 180,000 or less because the fluidity of the finally obtained resin composition is improved and the molding process becomes easy. A more preferable range of the number average molecular weight is 55,000 to 160,000, and particularly preferable is 60,000 to 140,000.

  The component (B-2) is a modified block copolymer obtained by graft polymerization of an α, β-unsaturated carboxylic acid to a hydrogenated product of such a block copolymer. In this graft polymerization, a radical generator may be used in combination with the α, β-unsaturated carboxylic acids. Examples of the α, β-unsaturated carboxylic acids and radical generator include the component (B-1). The compound used in manufacturing can be used, and the graft polymerization reaction can be performed in the same manner as in the component (B-1).

  Each of the (B-1) component and the (B-2) component may be used alone or in a combination of two or more in any combination and ratio. Moreover, you may mix and use 1 type, or 2 or more types of (B-1) component, and 1 type or 2 or more types of (B-2) component.

[Polymer component]
The polyamide resin composition excellent in low-temperature impact properties of the present invention comprises, as a polymer component, the above-described polyamide 5X as the component (A) and the modified elastomer as the component (B), the component (A): 90 to 50% by weight, Component (B): 10 to 50% by weight (however, the total of component (A) and component (B) is 100% by weight). When the component (A) is less than the above range and the component (B) is more than the above range, a good sea-island structure in which the dispersed phase of the component (B) is formed in the continuous phase of the component (A) can be formed. On the contrary, if the amount of the component (A) is larger than the above range and the amount of the component (B) is smaller than the above range, the amount of the modified elastomer is so small that the effect of improving the low temperature impact property cannot be sufficiently obtained.
Preferred blending ratios are (A) component: 85 to 50% by weight, (B) component: 15 to 50% by weight, more preferably (A) component: 80 to 55% by weight, and (B) component: 20 to 20%. 45% by weight
It is.

[Dispersed particle size]
In the polyamide resin composition excellent in low temperature impact property of the present invention, the component (B) is preferably dispersed as a dispersed phase in the continuous phase of the component (A). The 50-point average particle diameter of this dispersed phase is preferably 1 to 3 μm, particularly preferably 1.5 to 2.5 μm.
The fact that the 50-point average particle size is smaller than the lower limit is that, as mentioned above, the stress relaxation effect on the modified elastomer in the crystallization process of the polyamide resin is not sufficient, and a modified elastomer phase having a large residual stress is formed. A sufficient impact resistance improvement effect cannot be obtained. If this 50-point average particle size is larger than the above upper limit, deformation upon impact is large, resulting in a decrease in impact resistance and a decrease in flexural modulus, which is not preferable.

[Various additives and other polymer components]
<Various additives>
Various additives are blended in the polyamide resin composition of the present invention as necessary. Examples of additives include antioxidants, weathering agents, mold release agents, lubricants, pigments, dyes, crystal nucleating agents, plasticizers, antistatic agents, flame retardants, fillers, reinforcing materials, and conductivity-imparting agents. Can be mentioned.

Specifically, examples of the antioxidant or the heat stabilizer include hindered phenol compounds, hydroquinone compounds, phosphite compounds, and substituted products thereof.
Examples of weathering agents include resorcinol compounds, salicylate compounds, benzotriazole compounds, benzophenone compounds, hindered amine compounds, and the like.
Examples of the release agent or lubricant include aliphatic alcohols, aliphatic amides, aliphatic bisamides, bisurea compounds, and polyethylene waxes.
Examples of the pigment include phthalocyanine and carbon black.
Examples of the dye include nigrosine and aniline black.
Examples of the crystal nucleating agent include talc, silica, kaolin, clay and the like.
Examples of the plasticizer include octyl p-oxybenzoate and N-butylbenzenesulfonamide.

Examples of antistatic agents include alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, and betaine amphoteric antistatic agents. Can be mentioned.
Flame retardants include hydroxides such as melamine cyanurate, magnesium hydroxide, aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resins or brominated flame retardants thereof. And a combination of antimony trioxide and the like.

Fillers include graphite, barium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, antimony oxide, titanium oxide, aluminum oxide, zinc oxide, iron oxide, zinc sulfide, zinc, lead, nickel, aluminum, copper, iron, stainless steel , Bentonite, montmorillonite, synthetic mica, and other particulate, needle-like and plate-like fillers.
Examples of the reinforcing material include glass fiber, glass flake, carbon fiber, boron nitride, potassium titanate, and aluminum borate.

These additives may be used individually by 1 type, and 2 or more types may be mixed and used for them in arbitrary combinations and ratios.
If the blending amount of these additives is too small, the blending effect cannot be sufficiently obtained, but if too large, the moldability and mechanical properties are impaired, so the sum of the components (A) and (B) The total amount of additives is preferably 30 parts by weight or less with respect to 100 parts by weight.

<Other polymer components>
Examples of other polymer components include polyamide resins other than polyamide 5X, polyethylene, polypropylene, polyester, polycarbonate, polyphenylene ether, polyphenylene sulfide, liquid crystal polymer, polysulfone, polyether sulfone, ABS resin, SAN resin, polystyrene, and the like.
These other polymer components may be used alone or in a combination of two or more in any combination and ratio.
When blending these other polymer components, if the blending amount is too large, the effects of the components (A) and (B) used in the present invention are impaired. The amount is preferably 1 part by weight or less as the total amount of other polymer components with respect to 100 parts by weight of the total of component (A) and component (B).

  The various additives and other polymer components described above are the manufacturing process of the component (A) and the component (B) used in the present invention, the manufacturing process of the polyamide resin composition having excellent low temperature impact properties of the present invention, and the molding thereof. It can mix | blend in arbitrary processes among processes.

[Production method]
In order to produce the polyamide resin composition having excellent low-temperature impact properties of the present invention, the above-mentioned components (A) and (B) are mixed together with additives and other polymer components used as necessary. Mix by means.

  The known mixing means is not particularly limited, and examples thereof include a melt kneading method using a twin screw extruder or a single screw extruder, a dry blend using a tumbler, a super mixer, a Henschel mixer, or a Nauter mixer.

Specifically, for example, a method of melt kneading the component (A) and the component (B) can be mentioned.
Another method includes dry blending the component (A) and the component (B).
When melt-kneading, the conditions may be general polyamide resin melt-kneading conditions. For example, the peak top temperature of the endothermic peak measured by DSC of the polyamide 5X to be used (if there are two endothermic peaks, the higher one) The temperature for melting and kneading at a temperature setting of about 5 to 50 ° C. higher than the above temperature).

  The polyamide resin composition of the present invention can be molded into a desired shape by any molding method such as injection molding, film molding, melt spinning, blow molding or vacuum molding. Examples of the molded product include injection molded products, films, sheets, filaments, tapered filaments, fibers, and the like.

[Charpy impact value]
The polyamide resin composition excellent in low-temperature impact properties of the present invention is excellent in low-temperature impact properties, and the preferred one is a notched Charpy impact value (−30 ° C.) measured by the method described in the Examples section below. There 70 kJ / ^{m 2} or more, showing a high impact value of particular 80 kJ / ^{m 2} or more.

[Injection molded products]
The polyamide resin composition of the present invention can produce an injection molded product by a known injection molding method.
As an injection molding machine used to obtain an injection molded product, for example, NISSEI Plastics Co., Ltd .: NEX80 type, Toshiba Machine Co., Ltd .: IS80, etc. may be mentioned.
The injection molding conditions in the injection molding method are not particularly limited, and are appropriately selected within the range of conditions for molding known polyamide resins such as polyamide 6 and polyamide 66.

[Extruded product]
The polyamide resin composition of the present invention can produce an extruded product by a known extrusion method.
The known extrusion molding method is not particularly limited, and examples thereof include flat film molding using a T die, water-cooled or air-cooled inflation film molding, tube molding, monofilament molding, and multifilament molding. Further, examples of the extruder used in the extrusion method include known single-screw and twin-screw extruders.

[Usage]
The molded product formed by molding the polyamide resin composition having excellent low temperature impact properties of the present invention has mechanical properties such as chemical resistance and flexural modulus inherent to the polyamide resin, and also has excellent low temperature impact properties. It is extremely useful industrially as part or all of various electric / electronic / OA parts such as automobiles, railcar parts, computer parts, mobile phone parts, home appliance parts, etc. is there.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited by the following examples unless it exceeds the gist.

[Measurement methods for various physical properties and characteristics]
(1) Relative viscosity of polyamide resin (η _r )
The relative viscosity (η _r ) of the polyamide resin was measured by preparing a solution (concentration: 0.01 g / ml) of the polyamide resin in 98% sulfuric acid and using an Ostwald viscometer at 25 ° C.

(2) Endothermic peak temperature of the polyamide resin The endothermic peak temperature of the polyamide resin is measured by using a differential scanning calorimeter ("Diamond DSC" manufactured by Perkin Elmer) in a nitrogen atmosphere by a differential scanning calorimetry (DSC) method. Measured. About 5 mg of a polyamide resin sample is expected to reach a temperature 50 ° C. higher than the expected peak top temperature of the endothermic peak (if there are two endothermic peaks, the temperature at the top of the endothermic peak on the high temperature side), 20 ° C./min The sample was heated at a rate of 5 ° C and held for 3 minutes to completely melt the sample, and then the temperature was lowered to 30 ° C at a rate of temperature drop of 20 ° C / min. Subsequently, after holding at 30 ° C. for 3 minutes, the temperature at the peak top of the endothermic peak observed when the temperature was raised at a rate of temperature rise of 20 ° C./min was measured.

(3) Terminal amino group concentration of polyamide resin 0.1 to 0.2 g of polyamide resin sample was accurately weighed and dissolved in 50 ml of phenol (manufactured by Hayashi Junyaku Kogyo Co., Ltd.), and then an automatic titrator (Mitsubishi Chemical Corporation). The product was calculated by titration with 0.1N hydrochloric acid using “GT-06” manufactured by the company (unit: μeq / g).

(4) Charpy impact value After cutting a notch with a tip notch R = 0.25 mm at the longitudinal center of a bending test piece obtained by the method described below, conditioning was performed for 4 hours in a thermostatic bath at -30 ° C. Then, according to ISO179, the Charpy impact test under -30 degreeC was implemented.

(5) 50-point average particle diameter of the dispersed phase of the modified elastomer After cutting a notch with a tip notch R = 0.25 mm at the center in the longitudinal direction of the test piece obtained by the method described below, it was immersed in liquid nitrogen for 10 minutes. The Charpy impact test was immediately conducted. The specimen including the fracture surface after the Charpy impact test was immersed in a 90 ° C. p-xylene bath for 1 hour to etch the dispersed phase composed of the modified elastomer. Then, after air-drying at 23 ° C. and 50% RH for 24 hours, aluminum deposition was performed, and the fracture surface after the Charpy impact test in which the modified elastomer dispersed phase was etched with SEM-2500 manufactured by Hitachi, Ltd. was observed. The particle size of the dispersed phase of any 50 modified elastomers was measured, and the number average value was calculated.

(6) Bending elastic modulus Using a bending test piece obtained by the method described below, a bending test was performed at 23 ° C. and 50% RH in accordance with ISO178.

[Component (B): Preparation of Modified Elastomer]
As the component (B), the following commercially available modified elastomer was used.
m-EBR: Maleic anhydride-modified EBR “Modic AP730T” manufactured by Mitsubishi Chemical Corporation
m-EPR: Maleic anhydride-modified EPR “Modic APS501” manufactured by Mitsubishi Chemical Corporation
m-SEBS: manufactured by Asahi Kasei Corporation Maleic anhydride-modified SEBS “Tuftec M1943”, styrene content 20% by weight

[Preparation of monomer for polycondensation]
Commercial products were used for ε-caprolactam, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, and hexamethylenediamine.
ε-caprolactam: manufactured by Mitsubishi Chemical Corporation adipic acid: manufactured by Asahi Kasei Chemicals Co., Ltd. sebacic acid: manufactured by Ogura Gosei Co., Ltd. azelaic acid: manufactured by cognis, Inc. dodecanedioic acid: manufactured by Ube Industries, Ltd. hexamethylenediamine: manufactured by Asahi Kasei Chemicals Co., Ltd.

[Preparation of monomer for polymerization]
Pentamethylenediamine was prepared by the following operation.

<Preparation of pentamethylenediamine / adipate aqueous solution>
Using a cadA amplified strain, an aqueous pentamethylenediamine / adipate solution was prepared by the following method using lysine / adipate as a raw material.

E. E. coli JM109 / pCAD1 was pre-cultured in 10 flasks containing LB medium, then 1 L of the culture solution was inoculated into a 200 L jar fermenter containing 99 L of LB medium, and aerated at 0.5 vvm, 35 ° C., 250 rpm. Stirring culture was performed.
Six hours after the start of the culture, the whole culture solution was inoculated into a 5 m ³ volume culture tank containing 3 m ³ of 2 × LB medium and further cultured. The culture conditions in a 5 m ³ volume culture tank were an aeration rate of 0.5 vvm and 35 ° C. The stirring rotation speed was adjusted in the range of 60 to 100 rpm so that the dissolved oxygen concentration had a sufficiently high value. At 4 hours of culture, sterilized IPTG (isopropyl-β-D-thiogalactopyranoside) was added to a final concentration of 0.5 mM, and then the culture was continued for 14 hours.

  Under the conditions of 6,400 rpm and a feed rate of 750 L / hr, the cells were collected from the culture solution using an Alfa Laval separator. The wet weight of the collected cells was 36.9 kg. The wet cells were suspended in 160 L of a 10 mM sodium acetate solution, and then recovered again with a sharp press centrifuge at 15,000 rpm and a feed rate of 1.0 L / min. 18.7 kg of wet cells Acquired the body.

Adipic acid was added to a 50% (w / v) lysine base solution (manufactured by Kyowa Hakko Kogyo Co., Ltd.) to a pH of 6.0 to prepare a concentrated solution of lysine / adipate. A substrate solution (3 m ³ ) was prepared so as to have a lysine concentration of 60 g / L, and placed in a 5 m ³ culture tank. Pyridoxal phosphate was added to the substrate solution to 0.1 mM, and E. coli was further added. coli
The reaction was started by adding cells of JM109 / pCAD1 so that OD660 was 0.5.

The reaction conditions were 37 ° C., 0.5 vvm aeration, and 70 rpm. The pH of the solution during the reaction was controlled to be 6.5 by adding a slurry in which 250 kg of adipic acid was suspended in 400 L of ion-exchanged water.
Further, a substrate concentrated solution (600 L) having a lysine concentration of 318 g / L was continuously fed at about 130 L / h from the start, and the whole amount was added in about 4.5 hours. The reaction was further continued for a total of 22 hours.

At the end of the reaction, the residual concentration of lysine was 0.03 g / L or less, and almost 100% of lysine was converted to pentamethylenediamine.
The solution after the reaction (about 4 m ³ ) is passed through a UF membrane module ACP-3053 (manufactured by Asahi Kasei Kogyo Co., Ltd.) that cuts off a molecular weight of 13,000 or more after performing inactivation treatment (80 ° C., 30 min) of bacterial cells. High molecular weight impurities were removed.
The recovery rate by UF treatment was 99.3%. As described above, an aqueous solution of pentamethylenediamine / adipate containing approximately equimolar amounts of pentamethylenediamine and adipic acid was obtained.

<Purification and isolation of pentamethylenediamine adipate>
An activated carbon tower having a diameter of 700 mm was charged with activated carbon “MM-11” (105 kg, about 440 L) manufactured by Mitsubishi Chemical Calgon Co., Ltd., and deionized water was passed through for 2 days. Next, the pentamethylenediamine / adipate aqueous solution (about 4 m ³ ) was passed at a rate of 1.32 m ³ / h, and finally 500 L of demineralized water was passed. After initially purging 460 L, an activated carbon-treated pentamethylenediamine / adipate aqueous solution was collected.
Before the activated carbon treatment, 4076.5 kg of an aqueous solution of pentamethylenediamine / adipate and 603.9 kg of pentamethylenediamine / adipate contained were contained. After the activated carbon treatment, there were 5029 kg of a pentamethylenediamine / adipate aqueous solution and 603.7 kg of the pentamethylenediamine / adipate contained.

Through PP pleated cartridge filter TCP-JX, starting concentrated pentamethylene diamine adipate aqueous solution after the activated carbon treatment were charged into a 2m ³ stirred tank, jacket temperature 110 ° C., internal temperature 57 ° C., at a vacuum degree 140Torr~150Torr Then, concentration was performed while appropriately charging the aqueous solution of pentamethylenediamine / adipate after the activated carbon treatment.
The weight of the concentrate was 918.4 kg, and the concentration of pentamethylenediamine / adipate was 63.5% by weight.

  The concentration of pentamethylenediamine in the aqueous solution of pentamethylenediamine / adipate such as the concentrated solution was titrated with a 1N-HCl aqueous solution and calculated from the titration amount up to the inflection point of pH. Similarly, the concentration of adipic acid in the pentamethylenediamine / adipate aqueous solution such as the concentrated solution was titrated with a 1N-NaOH aqueous solution and calculated from the titration amount up to the inflection point of pH. For titration, an automatic titration apparatus (GT-06 model manufactured by Mitsubishi Chemical Corporation) was used.

Next, crystallization was performed in the same 2 m ³ stirring tank. The stirring blades are three retreating blades, the stirring speed is 40 rpm, and the cooling rate is 8 ° C./h.
When the internal temperature is 37.4 ° C., 1 kg of pentamethylenediamine / adipate prepared in advance is added as a seed crystal to precipitate crystals, and the crystallization is completed at an internal temperature of 10.5 ° C. An acid salt slurry was obtained. Incidentally, pentamethylenediamine adipate as a seed crystal was prepared on a lab scale according to this example.

  Using a centrifugal filter having a diameter of 1.22 m, the pentamethylenediamine / adipate slurry was centrifugally filtered in three portions. The rotation speed is 980 rpm, the mother liquor shake-off time is 15 minutes, and after the mother liquor is shaken off, about 12 kg of demineralized water at 10 ° C. (about 12 kg of demineralized water is about 20% by weight of the expected wet cake weight) is sprinkled and washed. The demineralized water was shaken off for 15 minutes.

By the above operation, pentamethylenediamine adipate (pentamethylenediamine adipate) having a water content of about 15% by weight was obtained as a seed crystal.
Next, demineralized water (100 kg) and pentamethylenediamine adipate (250 kg) having a water content of about 15% by weight were charged into a 1 m ³ stainless steel container previously purged with nitrogen, and dissolved by stirring.
Next, a 25% by weight aqueous sodium hydroxide solution (273.8 kg) was charged into the solution and neutralized (that is, pentamethylenediamine was desalted to give a free amine). When the sodium hydroxide aqueous solution was charged into the solution, the internal temperature of the solution was adjusted so as not to exceed 70 ° C.
From the neutralized solution, water was distilled off under conditions of an internal temperature of 50 ° C. and a reduced pressure of 50 Torr, and then pentamethylenediamine was distilled under the conditions of an internal temperature of 80 ° C. and a reduced pressure of 20 Torr. The obtained pentamethylenediamine was distilled again under the conditions of an internal temperature of 80 ° C. and a reduced pressure of 20 Torr to obtain pentamethylenediamine having a sodium content of about 2 ppm.

[Production of polyamide resin]
(1) Polyamide 6
50 kg of ε-caprolactam, 1.5 kg of demineralized water, and 3.48 g of disodium hydrogen phosphite pentahydrate were placed in a container, purged with nitrogen, and dissolved at 100 ° C. This raw material aqueous solution was transferred to an autoclave, the jacket temperature was set to 280 ° C., and heating was started. After the temperature of the contents was raised to 270 ° C., the pressure in the autoclave was gradually released, and the polycondensation reaction was terminated when the pressure was further reduced to reach a predetermined stirring power. After completion of the reaction, the pressure was restored with nitrogen, and the contents were introduced into a cooling water tank in the form of a strand and then pelletized with a rotary cutter. Unreacted monomers and oligomers were extracted and removed from the obtained pellets using 1.5 times the amount of boiling water of the obtained pellets. The pellets from which the unreacted material had been removed were dried at 120 ° C. and 1 torr (0.13 kPa) until the water content became 0.1% by weight or less to obtain polyamide 6.
Polyamide 6 had a relative viscosity (η _r ) of 2.8, an endothermic peak temperature of 224 ° C., and a terminal amino group concentration of 32 μeq / g.

(2) Polyamide 56
Pentamethylenediamine, adipic acid, and demineralized water are put in a container so that a concentration of 50% by weight and a quantity of 100 kg of pentamethylenediamine / adipate aqueous solution is obtained, and 3.48 g of disodium hydrogen phosphite pentahydrate is added. Was put in a container and the mixture was dissolved in a nitrogen atmosphere to obtain a raw material aqueous solution. The raw material aqueous solution was transferred to an autoclave which had been previously purged with nitrogen by a plunger pump. The jacket temperature was adjusted to 280 ° C., the autoclave pressure was adjusted to 1.47 MPa, and the contents were heated to 270 ° C. Next, after gradually releasing the pressure in the autoclave, the pressure was further reduced and the polycondensation reaction was terminated when a predetermined stirring power was reached. After completion of the reaction, the pressure was restored with nitrogen, and the contents were introduced into a cooling water tank in the form of a strand and then pelletized with a rotary cutter. The obtained pellets were dried under the conditions of 120 ° C. and 1 torr (0.13 kPa) until the water content became 0.1% by weight or less to obtain polyamide 56.
Polyamide 56 had a relative viscosity (η _r ) of 2.8, endothermic peak temperatures of 232 ° C. and 255 ° C., and a terminal amino group concentration of 33 μeq / g.

(3) Polyamide 510
Pentamethylenediamine, sebacic acid, and demineralized water are placed in a container so that the concentration is 50% by weight and a quantity of 100 kg of pentamethylenediamine / sebacate aqueous solution, and 3.48 g of disodium hydrogen phosphite pentahydrate is added. Was put in a container and the mixture was dissolved in a nitrogen atmosphere to obtain a raw material aqueous solution. The raw material aqueous solution was transferred to an autoclave which had been previously purged with nitrogen by a plunger pump. The jacket temperature was adjusted to 280 ° C., the autoclave pressure was adjusted to 1.47 MPa, and the contents were heated to 270 ° C. Next, after gradually releasing the pressure in the autoclave, the pressure was further reduced and the polycondensation reaction was terminated when a predetermined stirring power was reached. After completion of the reaction, the pressure was restored with nitrogen, and the contents were introduced into a cooling water tank in the form of a strand and then pelletized with a rotary cutter. The obtained pellets were dried under the conditions of 120 ° C. and 1 torr (0.13 kPa) until the water content became 0.1% by weight or less to obtain polyamide 510.
Polyamide 510 had a relative viscosity (η _r ) of 2.5, endothermic peak temperatures of 176 ° C. and 219 ° C., and a terminal amino group concentration of 35 μeg / g.

(4) Polyamide 59
Pentamethylenediamine, azelaic acid, and demineralized water are placed in a container so that the concentration is 50% by weight and a quantity of 100 kg of pentamethylenediamine / azeleate solution, and 3.48 g of disodium hydrogen phosphite pentahydrate is added. Was put in a container and the mixture was dissolved in a nitrogen atmosphere to obtain a raw material aqueous solution. Thereafter, polyamide 59 was obtained in the same manner as (2) production of polyamide 56.
Polyamide 59 had a relative viscosity (η _r ) of 2.8, endothermic peak temperatures of 190 ° C. and 210 ° C., and a terminal amino group concentration of 32 μeq / g.

(5) Polyamide 512
Pentamethylenediamine, dodecanedioic acid, and demineralized water are put in a container so that a concentration of 50% by weight and a quantity of 100 kg of pentamethylenediamine / dodecanedioate aqueous solution is obtained, and disodium hydrogen phosphite pentahydrate 3 .48 g was put in a container and the mixture was dissolved in a nitrogen atmosphere to obtain a raw material aqueous solution. Thereafter, polyamide 512 was obtained in the same manner as (2) production of polyamide 56.
Polyamide 512 had a relative viscosity (η _r ) of 2.8, endothermic peak temperatures of 173 ° C. and 211 ° C., and a terminal amino group concentration of 32 μeq / g.

(6) Polyamide 610
Hexamethylenediamine, sebacic acid, and demineralized water are put into a container so that the concentration is 50% by weight and a quantity of 100 kg of hexamethylenediamine / sebacate aqueous solution, and 3.48 g of disodium hydrogen phosphite pentahydrate is added. Was put in a container and the mixture was dissolved in a nitrogen atmosphere to obtain a raw material aqueous solution. The raw material aqueous solution was transferred to an autoclave which had been previously purged with nitrogen by a plunger pump. The jacket temperature was adjusted to 280 ° C., the autoclave pressure was adjusted to 1.47 MPa, and the contents were heated to 270 ° C. Next, after gradually releasing the pressure in the autoclave, the pressure was further reduced and the polycondensation reaction was terminated when a predetermined stirring power was reached. After completion of the reaction, the pressure was restored with nitrogen, and the contents were introduced into a cooling water tank in the form of a strand and then pelletized with a rotary cutter. The obtained pellets were dried under conditions of 120 ° C. and 1 torr (0.13 kPa) until the water content became 0.1% by weight or less to obtain polyamide 610.
Polyamide 610 had a relative viscosity (η _r ) of 2.8, an endothermic peak temperature of 222 ° C., and a terminal amino group concentration of 33 μeg / g.

(7) Polyamide 56/6 (56/6 charging weight ratio = 80/20)
Pentamethylenediamine, adipic acid, and demineralized water are put in a container so that the concentration is 50% by weight and a quantity of 80 kg of pentamethylenediamine / adipate solution. Further, ε-caprolactam 10 kg, disodium hydrogen phosphite 5 water 3.48 g of the Japanese product and 135 g of pentamethylenediamine were placed in a container, and the mixture was dissolved under a nitrogen atmosphere to obtain a raw material aqueous solution. The raw material aqueous solution was transferred to an autoclave which had been previously purged with nitrogen by a plunger pump. The jacket temperature was adjusted to 280 ° C., the autoclave pressure was adjusted to 1.47 MPa, and the contents were heated to 270 ° C. Next, after gradually releasing the pressure in the autoclave, the pressure was further reduced and the polycondensation reaction was terminated when a predetermined stirring power was reached. After completion of the reaction, the pressure was restored with nitrogen, and the contents were introduced into a cooling water tank in the form of a strand and then pelletized with a rotary cutter.
Unreacted monomers and oligomers were extracted and removed from the obtained pellets using 1.5 times the amount of boiling water of the obtained pellets. The pellets from which unreacted substances were removed were dried at 120 ° C. and 1 torr (0.13 kPa) until the water content became 0.1% by weight or less, and polyamide 56/6 (56/6 feed weight ratio = 80 / 20) was obtained.
Polyamide 56/6 had a relative viscosity (η _r ) of 3.5 and a terminal amino group concentration of 38 μeg / g. The endothermic peak temperatures were 181 ° C. and 216 ° C.

[Examples 1 to 10, Comparative Examples 1 to 5]
As shown in Table 1, the polyamide resin pellets of component (A) and the modified elastomer pellets of component (B) were mixed with a twin screw extruder “TEX-30” manufactured by Nippon Steel Works, with a cylinder temperature of 265 ° C. and a screw. Melt kneading was performed at a rotational speed of 200 rpm to obtain polyamide resin composition pellets. Next, after drying with a 120 ° C. vacuum dryer for 8 hours, using an injection molding machine (“SH100” manufactured by Sumitomo Heavy Industries, Ltd., mold clamping force 100 T), resin temperature (measured temperature of purge resin): 260 ° C., Bending test piece based on ISO178 was molded at a mold temperature of 80 ° C.

With respect to this bending test piece, the bending elastic modulus and Charby impact value were measured, and the results are shown in Table 1.
Table 1 also shows the 50-point average particle size of the dispersed phase of the modified elastomer of component (B).

From Table 1, it can be seen that by using polyamide 5X as the polyamide resin, high low-temperature impact properties can be obtained with a small amount of the modified elastomer and without impairing the flexural modulus.
In particular, by comparing Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 6 and Comparative Example 3, Example 5 and Comparative Example 4, respectively, this example using polyamide 5X as the polyamide resin. The polyamide resin composition of the invention has a marked improvement in low-temperature impact resistance by blending with a modified elastomer, despite having the same flexural modulus as compared with those using other general-purpose polyamide resins such as polyamide 6. It turns out that it shows an effect.
In addition, when the impact resistance at room temperature was examined in the same manner as described above for the polyamide resin compositions of the above Examples and Comparative Examples, there was no significant difference in impact resistance at room temperature, and polyamide 5X was used as the polyamide resin. It has been found that this effect is particularly effective for improving low temperature impact resistance. As described above, this effect is because polyamide 5X has higher reactivity between the amino group and the modified group of the modified elastomer than other general-purpose polyamide resins such as polyamide 6, and further, the solidification process. This is probably due to the small residual stress of the modified elastomer.

Claims (10)

Polyamide resin composition comprising 90 to 50% by weight of the following component (A) and 10 to 50% by weight of component (B) comprising the following component (B-1) and / or the following component (B-2) as the polymer component: A thing,
The following polyamide 5X has two endothermic peaks as measured by differential scanning calorimetry, the temperature difference between the peak tops of the two endothermic peaks is 10 to 50 ° C., and the terminal amino group concentration of the polyamide 5X is 16 A polyamide resin composition excellent in low-temperature impact property, characterized by being -100 μeq / g .
Component (A): a polyamide resin having a structure corresponding to a polycondensate obtained by a polycondensation reaction using a diamine containing pentamethylenediamine and a dicarboxylic acid as monomer components (hereinafter, this polyamide resin is referred to as “polyamide 5X”). Called.)
Component (B-1): formed by graft polymerization of an α, β-unsaturated carboxylic acid and / or a derivative thereof onto an olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 or more carbon atoms. Modified Polyolefin Copolymer (B-2) Component: An α, β-unsaturated carboxylic acid is added to a hydrogenated block copolymer containing a vinyl aromatic compound polymer block a and a conjugated diene compound polymer block b. Modified block copolymer obtained by graft polymerization of acid and / or derivative thereof   2. The low temperature according to claim 1, wherein the component (A) forms a continuous phase, and the 50-point average particle size of the dispersed phase comprising the component (B) in the component (A) is 1 to 3 μm. A polyamide resin composition having excellent impact properties. The polyamide having excellent low-temperature impact characteristics according to claim 1 or 2 , wherein the polyamide 5X is at least one selected from the group consisting of polyamide 56, polyamide 59, polyamide 510, polyamide 512 and 56/6. Resin composition. The low temperature impact according to any one of claims 1 to 3 , wherein the olefin copolymer in the component (B-1) is an ethylene-butene copolymer and / or an ethylene-propylene copolymer. Polyamide resin composition with excellent properties. In any one of claims 1 to 4, wherein (B-2) a hydrogenated product of a block copolymer in component is a styrene - the low-temperature impact resistance, which is a styrene copolymer - ethylene - butylene Excellent polyamide resin composition. The polyamide resin composition excellent in low-temperature impact property according to any one of claims 1 to 5 , wherein the α, β-unsaturated carboxylic acid is maleic anhydride. In any one of claims 1 to 6, polyamide resin composition having excellent low-temperature impact resistance which is notched Charpy impact value measured at -30 ° C. and characterized in that 70 kJ / m ² or more. An injection-molded product obtained by injection-molding the polyamide resin composition having excellent low-temperature impact properties according to any one of claims 1 to 7 . An extruded product obtained by extruding the polyamide resin composition having excellent low-temperature impact properties according to any one of claims 1 to 7 . An automobile / railway vehicle component or an electric / electronic / OA component, wherein at least part of the molded product according to claim 8 or 9 is formed.