JP2023142877A - Polyamide resin composition, and molded body - Google Patents

Abstract

To provide a polyamide resin composition which can suppress lowering of tensile strength of the polyamide resin composition while improving flowability in injection molding.SOLUTION: A polyamide resin composition contains a polyamide resin (A) having a melting point of 280°C or higher, 0.1-30 pts.mass of a fatty acid metal salt (B) with respect to 100 pts.mass of the polyamide resin (A), and 0.1-30 pts.mass of a lubricant (C). The polyamide resin (A) includes a constitutional unit derived from 20-100 mol% of a terephthalic acid, 0-80 mol% of a constitutional unit derived from an aromatic dicarboxylic acid other than the terephthalic acid, and a constitutional unit derived from aliphatic diamine or alicyclic diamine. The lubricant (C) contains aliphatic diamide (C1) obtained by reaction of a saturated aliphatic monocarboxylic acid having 10 to 30 carbon atoms in the main chain, and aliphatic diamine having 2 to 12 carbon atoms in the main chain.SELECTED DRAWING: None

Description

The present disclosure relates to a polyamide resin composition and a molded article.

Since polyamide resin has excellent moldability, mechanical properties, and chemical resistance, it has been widely used as a material for various parts such as clothing, industrial materials, automobiles, electrical/electronic, and industrial applications. It is being

In recent years, the environment in which such polyamide resins are used has tended to become mechanically more severe. For example, polyamide resins used in automobile parts and the like are required to have high mechanical strength so as to be used in place of metals to reduce weight. Furthermore, as the number of parts increases due to hybridization and the introduction of driving support systems, there is a demand for smaller parts, and polyamide resins are also required to have high moldability. That is, polyamide resins are required to have excellent moldability as well as excellent mechanical strength.

A polyamide resin with improved mechanical strength is obtained by heating and extruding 50 mol% of a dicarboxylic acid mixture (containing 60 to 88% by mass of terephthalic acid and 12 to 40% by mass of isophthalic acid) and 50 mol% of hexamethylene diamine. Semi-aromatic polyamides have been proposed (for example, Patent Document 1).

Furthermore, a lubricant such as a fatty acid metal salt may be added to the polyamide resin composition in order to improve fluidity during injection molding and improve moldability. For example, a flame-retardant polyamide composition containing a semi-aromatic polyamide resin and a fatty acid metal salt is known (for example, Patent Document 2).

International Publication No. 2008/155271 International Publication No. 2008/126381

As mentioned above, the fluidity during injection molding can be improved by adding a fatty acid metal salt. However, the addition of fatty acid metal salts sometimes lowers the tensile strength of the polyamide resin composition. In particular, resin materials used for automobile parts are desired to have high tensile strength. That is, it is required to achieve a high level of both injection fluidity and tensile strength.

In view of these circumstances, the present disclosure provides a polyamide resin composition that can suppress a decrease in tensile strength of the polyamide resin composition while improving fluidity during injection molding, and a polyamide molded article containing the polyamide resin composition. The purpose is to provide

The polyamide resin composition of the present disclosure includes a polyamide resin (A) having a melting point of 280° C. or higher as measured by differential scanning calorimetry (DSC), and 0.1 to 0.1 to 100 parts by mass of the polyamide resin (A). The polyamide resin (A) contains 30 parts by mass of a fatty acid metal salt (B) and 0.1 to 30 parts by mass of a lubricant (C) based on 100 parts by mass of the polyamide resin (A), and the polyamide resin (A) contains dicarboxylic acid. It contains a structural unit derived from an acid and a structural unit derived from a diamine, and the structural unit derived from the dicarboxylic acid contains 20 to 100 mol% of terephthalate based on the total number of moles of the structural unit derived from the dicarboxylic acid. Contains a structural unit derived from an acid and a structural unit derived from 0 to 80 mol% of an aromatic dicarboxylic acid other than terephthalic acid, the structural unit derived from the diamine is a structural unit derived from an aliphatic diamine, The lubricant (C) contains at least one of the structural units derived from an alicyclic diamine, and the lubricant (C) contains a saturated aliphatic monocarboxylic acid having a main chain of 10 to 30 carbon atoms and a main chain having 2 to 12 carbon atoms. It includes an aliphatic diamide (C1) obtained by reacting with an aliphatic diamine.

The molded article of the present disclosure includes the polyamide resin composition of the present disclosure.

According to the present disclosure, there is provided a polyamide resin composition that can suppress a decrease in tensile strength of the polyamide resin composition while improving fluidity during injection molding, and a polyamide molded article containing the polyamide resin composition. I can do it.

1. Polyamide Resin Composition The polyamide resin composition of the present disclosure includes a polyamide resin (A), a fatty acid metal salt (B), and a lubricant (C).

1-1. Polyamide resin (A)
The polyamide resin (A) contains a structural unit (a1) derived from a dicarboxylic acid and a structural unit (a2) derived from a diamine.

The structural unit (a1) derived from dicarboxylic acid includes a structural unit derived from terephthalic acid. The content of the structural unit derived from terephthalic acid is preferably 20 to 100 mol%, and preferably 30 to 90 mol%, based on the total number of moles of the structural unit (a1) derived from dicarboxylic acid. More preferably, it is 60 to 80 mol%. When the content of the structural unit derived from terephthalic acid is 30 mol% or more, the melting point (Tm) of the polyamide resin (A) can be sufficiently increased, and the heat resistance and mechanical strength can be easily increased.

The structural unit (a1) derived from a dicarboxylic acid may further contain a structural unit derived from a dicarboxylic acid other than terephthalic acid. Examples of dicarboxylic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, 2-methylterephthalic acid, and naphthalenedicarboxylic acid; furandicarboxylic acids such as 2,5-furandicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. , alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid; malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethyl Included are aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as glutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, and suberic acid. Only one type of structural unit derived from a dicarboxylic acid other than terephthalic acid may be included, or two or more types may be included. Among them, from the viewpoint of easily maintaining heat resistance and low water absorption, the dicarboxylic acid constituent units other than the terephthalic acid constituent unit are preferably constituent units derived from aromatic dicarboxylic acids other than terephthalic acid, and the glass transition temperature From the viewpoint of easy adjustment of Tg below a certain level, a structural unit derived from isophthalic acid is more preferable.

The content of structural units derived from dicarboxylic acids other than terephthalic acid, preferably the content of structural units derived from aromatic dicarboxylic acids other than terephthalic acid, is based on the total number of moles of structural units (a1) derived from dicarboxylic acids. On the other hand, it is preferably 0 to 80 mol%, more preferably 10 to 70 mol%, and even more preferably 20 to 40 mol%. When the content is more than 0 mol%, the fluidity of the polyamide resin composition can be more easily improved. When the content is 80 mol% or less, the heat resistance of the polyamide resin composition is less likely to be impaired.

The structural unit (a2) derived from diamine contains at least one of a structural unit derived from an aliphatic diamine and a structural unit derived from an alicyclic diamine, and preferably contains a structural unit derived from an aliphatic diamine.

The structural unit derived from an aliphatic diamine is preferably a structural unit derived from an aliphatic diamine having 4 to 15 carbon atoms, preferably 6 to 12 carbon atoms. Examples of aliphatic diamines include 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1 , 11-diaminoundecane, 1,12-diaminododecane, etc., and branched alkylene diamines such as 2-methyl-1,5-diaminopentane, 2-methyl-1,8-diaminooctane, etc. included. Only one type of structural unit derived from aliphatic diamine may be included, or two or more types may be included. Among these, linear alkylene diamines are preferred, and 1,6-diaminohexane is more preferred.

The content of the structural unit derived from the aliphatic diamine is preferably 50 to 100 mol%, and preferably 80 to 100 mol%, based on the total number of moles of the structural unit (a2) derived from the diamine. More preferred. When the content of the structural unit derived from aliphatic diamine is 50 mol% or more, the fluidity of the polyamide resin composition during molding can be more easily improved.

The structural unit derived from an alicyclic diamine is preferably a structural unit derived from an alicyclic diamine having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms. Examples of alicyclic diamines include 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(aminomethyl)cyclohexane, and the like.

The structural unit (a2) derived from diamine may further contain a structural unit derived from other diamines other than those mentioned above. Examples of other diamines include aromatic diamines such as p-phenylene diamine, m-phenylene diamine, 4,4'-diaminobiphenyl, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, and the like.

In a preferred example of the polyamide resin (A), the structural unit (a1) derived from dicarboxylic acid is a structural unit derived from terephthalic acid and the structural unit derived from isophthalic acid, and the structural unit (a2) derived from diamine. is a polyamide resin whose structural unit is derived from 1,6-hexanediamine.

The molecular ends of the polyamide resin (A) may be capped with an end capping agent.

Examples of terminal capping agents include monocarboxylic acids and monoamines. Examples of monocarboxylic acids include aliphatic monocarboxylic acids having 2 to 30 carbon atoms such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, and caprylic acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; benzoic acid; Aromatic monocarboxylic acids such as toluic acid, naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid and phenylacetic acid are included. Examples of monoamines include aliphatic monoamines such as butylamine, amylamine, hexylamine, etc.; and araliphatic monoamines such as benzylamine, methylbenzylamine. Among these, since the molecular terminal of the polyamide resin (A) is often an amino group, the terminal capping agent is preferably a monocarboxylic acid.

The glass transition temperature (Tg) of the polyamide resin (A) measured by differential scanning calorimetry (DSC) is preferably 100 to 160°C, more preferably 120 to 145°C. When the Tg of the polyamide resin (A) is 100° C. or higher, molecular movement at high temperatures is suppressed, making it easier to improve heat resistance. When the Tg of the polyamide resin (A) is 160° C. or less, it is easier to increase the solidification rate when the molten polyamide resin composition is cooled, and the cycle time during injection molding can be further shortened.

The polyamide resin (A) preferably has a melting point (Tm) of 280 to 340° C. as measured by a differential scanning calorimeter (DSC). When the melting point of the polyamide resin (A) is 280°C or higher, it is easy to sufficiently increase the mechanical strength and heat resistance of the polyamide resin composition, and when it is 340°C or lower, there is no need to increase the molding temperature excessively. , thermal decomposition of the resin and other components during melt molding can be further suppressed. The melting point of the polyamide resin (A) is more preferably 300 to 330°C.

The melting point (Tm) and glass transition temperature (Tg) of the polyamide resin (A) can be measured using a differential scanning calorimeter (eg, Model DSC220C, manufactured by Seiko Instruments Inc.).

Specifically, about 5 mg of polyamide resin is sealed in an aluminum pan for measurement, and heated from room temperature to 350° C. at a rate of 10° C./min. Hold at 350°C for 3 minutes to completely melt the resin, then cool to 30°C at 10°C/min. After leaving at 30°C for 5 minutes, heating is performed a second time to 350°C at 10°C/min. The temperature (° C.) of the endothermic peak in this second heating is defined as the melting point (Tm) of the polyamide resin, and the displacement point corresponding to the glass transition is defined as the glass transition temperature (Tg).

The melting point and glass transition temperature of the polyamide resin (A) can be adjusted by adjusting the type of dicarboxylic acid or diamine that constitutes the polyamide resin (A). For example, if the content of structural units derived from terephthalic acid is increased, the melting point and glass transition temperature of the polyamide resin (A) tend to increase.

The intrinsic viscosity [η] of the polyamide resin (A) measured in 96.5% sulfuric acid at a temperature of 25°C is preferably 0.7 to 1.6 dl/g, and 0.8 to 1.2 dl. /g is more preferable. When the intrinsic viscosity [η] of the polyamide resin (A) is 0.7 dl/g or more, it is easy to sufficiently increase the mechanical strength of the polyamide resin composition, and when it is 1.6 dl/g or less, the polyamide resin composition Fluidity during molding is less likely to be impaired.

The intrinsic viscosity of the polyamide resin (A) can be measured by the following method. First, about 0.5 g of polyamide resin (A) is dissolved in 50 ml of 96.5% concentrated sulfuric acid. Then, the number of seconds of flow of the obtained solution under the condition of 25° C.±0.05° C. is measured using an Ubbelohde viscometer. Thereafter, the limiting viscosity is calculated based on the following formula.
[η]=ηSP/(C(1+0.205ηSP))

In the above formula, each algebra or variable represents the following.
[η]: Intrinsic viscosity (dl/g)
ηSP: Specific viscosity C: Sample concentration (g/dl)

The above ηSP is determined by the following formula.
ηSP=(t-t0)/t0
t: Number of seconds for sample solution to flow down (seconds)
t0: Number of seconds for blank sulfuric acid flow (seconds)

The polyamide resin can be produced, for example, by polycondensing the above dicarboxylic acid and diamine in a homogeneous solution. Specifically, a lower condensate is obtained by heating a dicarboxylic acid and a diamine in the presence of a catalyst as described in WO 03/085029, and then this lower condensate is It can be produced by applying shear stress to the melt and causing polycondensation.

From the viewpoint of adjusting the intrinsic viscosity of the polyamide resin, the above-mentioned terminal capping agent may be added to the reaction system. The intrinsic viscosity [η] (or molecular weight) of the polyamide resin can be adjusted by the amount of the terminal capping agent added.

The terminal capping agent is added to the reaction system of dicarboxylic acid and diamine. The amount added is preferably 0.07 mol or less, more preferably 0.05 mol or less, per 1 mol of the total amount of dicarboxylic acids.

The content of the polyamide resin (A) is preferably 25 to 90% by mass, more preferably 50 to 70% by mass, based on the polyamide resin composition. When the content of the polyamide resin (A) is within the above range, the heat resistance can be sufficiently increased without impairing the moldability of the polyamide resin composition.

1-2. Fatty acid metal salt (B)
The fatty acid metal salt (B) is used for the purpose of improving the fluidity of the resin composition during injection molding.

The fatty acid constituting the fatty acid metal salt (B) is preferably a higher fatty acid. Examples of higher fatty acids include higher fatty acids having 15 to 30 carbon atoms such as stearic acid, oleic acid, behenic acid, behenic acid, and montanic acid.

Examples of metals constituting the fatty acid metal salt (B) include calcium, magnesium, barium, lithium, aluminum, zinc, sodium, potassium, and the like.

Among these, calcium stearate, magnesium stearate, barium stearate, calcium behenate, sodium montanate, calcium montanate, and the like are preferred, and from the viewpoint of heat resistance, sodium montanate is more preferred.

The content of the fatty acid metal salt (B) is not particularly limited, but is preferably 0.1 to 30 parts by mass, and preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the polyamide resin (A). is more preferable. When the content is 0.1 part by mass or more, the fluidity during molding is likely to be further enhanced. When the content is 30 parts by mass or less, when solidifying the polyamide resin composition in a molten state, aggregation of the fatty acid metal salt (B) can be made more difficult to occur, so that a decrease in tensile strength can be further suppressed.

1-3. Lubricant (C)
The lubricant (C) may be used for the purpose of suppressing aggregation or precipitation of the fatty acid metal salt (B) when cooling the resin composition after molding. Note that the lubricant (C) is different from the fatty acid metal salt (B). The lubricant (C) contains an aliphatic diamide (C1).

As mentioned above, since the fatty acid metal salt (B) is in a liquid state when it is heated and melted, it is easy to reduce the viscosity of the polyamide resin composition and improve the fluidity of the polyamide resin composition. On the other hand, when the molten polyamide resin composition is cooled and solidified, the polyamide resin (A) and the fatty acid metal salt (B) solidify at different timings, so the fatty acid metal salt (B) tends to aggregate. , the tensile strength of the polyamide resin composition sometimes decreased. Such a phenomenon was particularly likely to occur when the amount of fatty acid metal salt (B) was increased.

In contrast, in the present disclosure, by adding aliphatic diamide (C1), the decrease in tensile strength of the polyamide resin composition can be suppressed. Although the reason for this is not clear, since the aliphatic diamide (C1) has an amide bond, it is easily compatible with the polyamide resin (A). Moreover, since the aliphatic diamide (C1) has an aliphatic chain, it also has an affinity with the fatty acid metal salt (B). That is, the aliphatic diamide can function as a compatibilizer between the polyamide resin (A) and the fatty acid metal salt (B). It is thought that this improves the dispersibility of the fatty acid metal salt (B), thereby suppressing a decrease in the tensile strength of the polyamide resin composition. In addition, since aliphatic diamide (C1) has more aliphatic chains and amide bonds than, for example, aliphatic monoamide, it is particularly easy to function as a compatibilizer between polyamide resin (A) and fatty acid metal salt (B). It is thought that bleeding of aliphatic diamide (C1) can also be suppressed.

1-3-1. Aliphatic diamide (C1)
Aliphatic diamide (C1) is a diamide compound obtained by reacting a saturated aliphatic monocarboxylic acid and an aliphatic diamine.

Since the saturated aliphatic monocarboxylic acid constituting the aliphatic diamide (C1) does not have an unsaturated structure, it is difficult to react or interact with, for example, the aromatic ring of the polyamide resin (A), which improves fluidity. It is thought to promote this. The saturated aliphatic monocarboxylic acid is preferably a higher saturated fatty acid. The number of carbon atoms in the main chain of the saturated aliphatic monocarboxylic acid is preferably 10 to 30, more preferably 15 to 20. Such an aliphatic monocarboxylic acid has a similar structure to the fatty acid constituting the fatty acid metal salt (B), and thus has a high affinity with the fatty acid. Examples of saturated aliphatic monocarboxylic acids include lauric acid (C12), stearic acid (C18), behenic acid (C22), and montanic acid (C28).

The number of carbon atoms in the main chain of the aliphatic diamine constituting the aliphatic diamide (C1) is preferably 2 to 12, more preferably 2 to 9. Examples of aliphatic diamine (C1) include ethylenediamine, butanediamine, hexanediamine, and the like.

Examples of the aliphatic diamide (C1) include ethylene bis stearamide, ethylene bis lauryl amide, ethylene bis behenylamide, butylene bis stearamide, and the like, with ethylene bis stearamide being preferred. These may be used alone or in combination of two or more.

The content of the aliphatic diamide (C1) is preferably 10 to 100 parts by mass, more preferably 10 to 79.5 parts by mass, based on 100 parts by mass of the lubricant (C). When the content is 10 parts by mass or more, aggregation and precipitation of the fatty acid metal salt (B) can be suppressed when the polyamide resin composition is cooled after molding.

In addition, the content ratio (C1/B) of aliphatic diamide (C1) and fatty acid metal salt (B) should be 0.01 to 10 (mass ratio) from the viewpoint of achieving both high fluidity and tensile strength. is preferable, and more preferably 0.1 to 5 (mass ratio). When C1/B is at least the lower limit, it is easier to suppress a decrease in the tensile strength of the polyamide resin composition, and when it is at most the upper limit, it is easier to improve the fluidity of the polyamide resin composition.

1-3-2. Low density polyethylene (C2)
It is preferable that the lubricant (C) further contains low density polyethylene (C2). Low density polyethylene (C2) can be used for the purpose of further increasing the fluidity of the polyamide resin composition and making it easier to disperse the aliphatic diamide (C1) in the vicinity of the fatty acid metal salt (B).

The low density polyethylene (C2) is preferably an ethylene homopolymer, but may also be a copolymer of ethylene and a small amount of α-olefin having 3 to 12 carbon atoms (eg, propylene, etc.). The content of structural units derived from ethylene in the copolymer is preferably 90.0 to 99.9% by mass, more preferably 93.0 to 99.9% by mass. On the other hand, the amount of the structural unit derived from α-olefin having 3 to 12 carbon atoms is preferably 0.1 to 10.0% by mass, preferably 0.1 to 7.0% by mass.

The low density polyethylene (C2) may be high pressure low density polyethylene. High-pressure low-density polyethylene is generally polyethylene obtained by radical polymerizing ethylene under high temperature and high pressure. The manufacturing method is not particularly limited, but includes, for example, a radical polymerization method in which radical polymerization is carried out under conditions of 500 to 2,000 atmospheres and 150 to 300°C. Examples of the polymerization initiator include organic peroxides.

The density of the low density polyethylene (C2) measured according to ASTM D1505 is preferably 900 to 925 kg/m ³ , more preferably 910 to 925 kg/m ³ .

The melt flow rate (MFR) of low density polyethylene (C2) measured in accordance with ASTM D1238 at 190°C and a load of 2.16 kg is preferably 0.1 to 50 g/10 minutes, more preferably 1 to 20 g/10 minutes.

The content of low density polyethylene (C2) is preferably 0 to 90 parts by weight, more preferably 10 to 79.5 parts by weight, based on 100 parts by weight of the lubricant (C). When the content is 10 parts by mass or more, the fluidity during molding is likely to be further enhanced. When the content is 79.5 parts by mass or less, decomposition gas derived from low-density polyethylene (C2) can be sufficiently suppressed, and poor appearance during molding can be suppressed.

1-3-2. Copolymer (C3)
It is preferable that the lubricant (C) further includes a copolymer (C3) having a structural unit derived from an olefin and a structural unit derived from an α,β-unsaturated carboxylic acid ester. The copolymer (C3) can further suppress aggregation of the fatty acid metal salt (B) when the polyamide resin composition is cooled and solidified, and can further suppress a decrease in tensile strength.

Although the reason is not clear, it is thought to be as follows. Since the copolymer (C3) has a structural unit derived from an olefin, it is easily compatible with the fatty acid metal salt (B) and the low density polyethylene (C2). Furthermore, since the copolymer (C3) has a polar moiety derived from an α,β-unsaturated carboxylic acid ester, it is easily compatible with the polyamide resin (A) and the aliphatic diamide (C1). Thereby, the copolymer (C3) acts as a compatibilizer between the polyamide resin (A) and the fatty acid metal salt (B) and between the aliphatic diamide (C1) and the low density polyethylene (C2). It seems to work. Further, it is thought that the copolymer (C3) tends to reduce the crystallization rate and melt viscosity of the polyamide resin composition when heated and melted.

Examples of the structural units derived from olefins constituting the copolymer (C3) include structural units derived from ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, and the like. Among these, structural units derived from ethylene are preferred.

Examples of structural units derived from α,β-unsaturated carboxylic acid esters constituting the copolymer (C3) include acrylic esters including methyl acrylate, ethyl acrylate, and butyl acrylate, and methacrylate. Contains structural units derived from methacrylic acid esters, including methyl acid, and ethyl methacrylate. Among these, from the viewpoint of heat resistance, structural units derived from acrylic acid C1-C10 alkyl esters such as methyl acrylate and n-butyl acrylate are preferred, and are easier to improve compatibility with low-density polyethylene (C2). From this viewpoint, structural units derived from C4 to C10 alkyl acrylate are more preferred, and structural units derived from n-butyl acrylate are even more preferred. The content of the structural units derived from the α,β-unsaturated carboxylic acid ester is preferably 5 to 70% based on the total of the structural units derived from the olefin and the structural units derived from the α,β-unsaturated carboxylic acid ester. % by mass, more preferably 10 to 50% by mass.

The copolymer (C3) may further contain other structural units than the above-mentioned structural units. Examples of other structural units include α,β-unsaturated carboxylic acid glycidyl esters such as acrylic acid glycidyl ester and methacrylic acid glycidyl ester; Glycidyl ether; Aromatic vinyl compounds such as styrene, α-methylstyrene, 4-methylstyrene, 4-methoxystyrene, chlorostyrene, and 2,4-dimethylstyrene; Unsaturated vinyl esters such as vinyl acetate and vinyl propionate. Contains the derived structural units.

Examples of the copolymer (C3) include ethylene/n-butyl acrylate copolymer, ethylene/methyl acrylate copolymer, and ethylene/ethyl acrylate copolymer, preferably ethylene/n-acrylate copolymer. It is an acid butyl copolymer. These may be used alone or in combination of two or more.

The melting point of the copolymer (C3) measured by differential scanning calorimetry (DSC) is preferably 40 to 120°C, more preferably 50 to 110°C. When the melting point of the copolymer (C3) is within this range, the fluidity of the polyamide resin composition during molding can be further improved.

The melt flow rate (MFR) of the copolymer (C3) measured in accordance with ASTM D1238 at 190°C and a load of 2.16 kg is preferably 1 to 400 g/10 minutes, more preferably 10 ~100g/10 minutes.

The content of the copolymer (C3) is preferably 0 to 80 parts by weight, more preferably 10 to 79.5 parts by weight, based on 100 parts by weight of the lubricant (C). When the content is 10 parts by mass or more, aggregation and precipitation of the fatty acid metal salt (B) when cooling the polyamide resin composition after molding can be further suppressed. When the content is 79.5 parts by mass or less, surface roughness of the molded article due to gas generation due to thermal decomposition of the copolymer (C3) can be further suppressed.

1-3-4. Aromatic carboxylic acid compound (C4)
It is preferable that the lubricant (C) further contains an aromatic carboxylic acid compound (C4). The aromatic carboxylic acid compound (C4) can further improve the fluidity of the polyamide resin composition.

The reason for this is not clear, but the aromatic carboxylic acid compound attacks the amide bonding site of the polyamide resin (A), cleaving the bond, and a reaction occurs in which the aromatic carboxylic acid compound is incorporated into the bond. Conceivable. That is, it is thought that this is because a reaction similar to hydrolysis occurs and the molecular weight of the polyamide resin (A) is appropriately reduced.

The aromatic carboxylic acid compound (C4) is an aromatic carboxylic acid, an anhydride thereof, or an alkyl (having 1 to 3 carbon atoms) ester thereof, and is preferably an aromatic carboxylic acid. The aromatic carboxylic acid has, for example, 7 to 15 carbon atoms.

Examples of the aromatic carboxylic acid compound (C4) include benzoic acid, 1-naphthalenecarboxylic acid, 2-naphthalenecarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene dicarboxylic acid. acids, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and anhydrides and alkyl C1-3 esters thereof, preferably terephthalic acid and isophthalic acid, more preferably terephthalic acid. be. These may be used alone or in combination of two or more.

The content of the aromatic carboxylic acid compound (C4) is preferably 0 to 80 parts by mass, more preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the lubricant (C). When the content is 0.5 parts by mass or more, fluidity during molding is likely to be further enhanced. When the content is 20 parts by mass or less, a decrease in mechanical strength due to excessive decomposition of the polyamide resin (A) can be sufficiently suppressed.

1-3-5. Common matters The lubricant (C) may be composed only of aliphatic diamide (C1), or may be composed of aliphatic diamide (C1), low density polyethylene (C2), copolymer (C3), and aromatic carboxylic acid compound. Any one or more of (C4) may be combined. Among them, from the viewpoint of achieving a higher degree of both fluidity and tensile strength of the polyamide resin composition, the lubricant (C) preferably contains low density polyethylene (C2) or a copolymer (C3); (C1), low density polyethylene (C2), and copolymer (C3); aliphatic diamide (C1), low density polyethylene (C2), and copolymer (C3). , it is more preferable that the aromatic carboxylic acid compound (C4) is included.

That is, the lubricant (C) contains 10 to 79.5 parts by mass of aliphatic diamide (C1) and 10 to 79.5 parts by mass of low density polyethylene (C2) per 100 parts by mass of the lubricant (C). , 10 to 79.5 parts by mass of the copolymer (C3), and 0.5 to 20 parts by mass of the aromatic carboxylic acid compound (C4).

The content ratio (C2/C1) of low density polyethylene (C2) to aliphatic diamide (C1) is, for example, preferably 0.1 to 10, more preferably 0.2 to 1. When the content ratio is at least the lower limit, it is easy to further improve the fluidity during injection molding while suppressing a decrease in the toughness of the polyamide resin composition. When the content ratio is below the upper limit, the decrease in toughness of the polyamide resin composition can be further suppressed.

The content ratio (C3/(C1+C2)) of the copolymer (C3) to the total amount of aliphatic diamide (C1) and low density polyethylene (C2) is preferably 0.1 to 10, for example, 0. More preferably, it is 2 to 5. When the content ratio is equal to or higher than the lower limit, the aliphatic diamide (C1) and the low-density polyethylene (C2) are easily compatible with each other, and the functions of each component are more easily expressed. When the content ratio is below the upper limit, thickening due to excessive reaction between the copolymer (C3) and the polyamide resin (A) during melting can be easily suppressed.

The content of the lubricant (C) is preferably 0.1 to 30 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polyamide resin (A). When the content is 0.1 parts by mass or more, aggregation and precipitation of the fatty acid metal salt (B) can be suppressed when the polyamide resin composition is cooled after molding. When the amount is 30 parts by mass or less, it is possible to further suppress a decrease in the tensile strength of the polyamide resin composition due to the lubricant (C) itself becoming a foreign substance.

Further, the content ratio (C/B) of the lubricant (C) and the fatty acid metal salt (B) is preferably 0.1 to 10 (mass ratio) from the viewpoint of achieving a high level of both fluidity and strength. It is more preferably 0.2 to 7 (mass ratio), and even more preferably 0.5 to 5 (mass ratio). When C/B is at least the lower limit, it is easier to suppress a decrease in the tensile strength of the polyamide resin composition, and when it is at most the upper limit, it is easier to improve the fluidity of the polyamide resin composition.

1-4. Other Components The polyamide resin composition of the present disclosure may further contain other components other than those described above, as long as the effects of the present disclosure are not impaired. Examples of other ingredients include reinforcing agents, nucleating agents, flame retardants, corrosion resistance improvers, anti-drip agents, ion scavengers, elastomers (rubbers), antistatic agents, mold release agents, antioxidants (phenolic amines, sulfurs, phosphorus, etc.), heat stabilizers (lactone compounds, vitamin E, hydroquinones, copper halides and iodine compounds, etc.), light stabilizers (benzotriazoles, triazines, benzophenones, benzoates, hindered amines, oxanilides, etc.), other polymers (polyolefins, olefin copolymers such as ethylene/propylene copolymers, ethylene/1-butene copolymers, propylene/1-butene copolymers, etc.) olefin copolymers, polystyrene, polyamides, polycarbonates, polyacetals, polysulfones, polyphenylene oxides, fluororesins, silicone resins, and LCP).

The reinforcing material (D) can impart high mechanical strength to the polyamide resin composition. Examples of reinforcing materials (D) include fibrous reinforcing materials such as glass fibers, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, zinc oxide whiskers, milled fibers and cut fibers. , as well as particulate reinforcement. Among these, one type may be used alone or two or more types may be used in combination. Among these, from the viewpoint of easily increasing the mechanical strength of the polyamide resin composition, fibrous reinforcing materials such as wollastonite, glass fiber, and potassium titanate whiskers are preferred, and wollastonite or glass fiber is more preferred.

The average fiber length of the fibrous reinforcing material may be, for example, 1 μm to 20 mm, preferably 5 μm to 10 mm, from the viewpoint of moldability, mechanical strength, and heat resistance of the polyamide resin composition. Further, the aspect ratio of the fibrous reinforcing material may be, for example, 5 to 2,000, preferably 30 to 600.

The average fiber length and average fiber diameter of the fibrous reinforcement can be measured by the following method.
1) After dissolving the resin composition in a hexafluoroisopropanol/chloroform solution (0.1/0.9% by volume), the resulting filtrate is collected by filtration.
2) Disperse the filtrate obtained in 1) above in water, and measure the fiber length (Li) and fiber diameter (di) of each of 300 arbitrary fibers using an optical microscope (magnification: 50x). The number of fibers having a fiber length of Li is set as qi, and the weight average length (Lw) is calculated based on the following formula, and this is taken as the average fiber length of the fibrous reinforcing material.
Weight average length (Lw) = (Σqi×Li ² )/(Σqi×Li)
Similarly, the number of fibers having a fiber diameter Di is set to ri, and the weight average diameter (Dw) is calculated based on the following formula, and this is set as the average fiber diameter of the fibrous reinforcing material.
Weight average diameter (Dw) = (Σri×Di ² )/(Σri×Di)

The content of the reinforcing material (D) is not particularly limited, but is preferably 1 to 300 parts by weight, more preferably 15 to 100 parts by weight, based on 100 parts by weight of the polyamide resin (A). When the content is within the above range, the mechanical strength of the polyamide resin composition can be further increased while ensuring fluidity during injection molding.

1-5. Physical Properties As described above, the polyamide resin composition of the present disclosure can maintain good tensile strength. The tensile strength of the polyamide resin composition measured in accordance with ASTM D638 depends on its composition, but is preferably, for example, 205 MPa or more, and more preferably 205 to 300 MPa.

Specifically, tensile strength can be measured by the following method.
First, an ASTM dumbbell-shaped test piece Type I having a thickness of 3.2 mm is prepared by injection molding under the following conditions.
Molding machine cylinder temperature: melting point (Tm) of polyamide resin composition + 10°C
Mold temperature: 120℃
Injection setting speed: 60mm/sec
Next, the obtained test piece was left in a nitrogen atmosphere at a temperature of 23°C for 24 hours, and then subjected to a tensile test in accordance with ASTM D638 at a temperature of 23°C and a relative humidity of 50% to determine the tensile strength. Measure.

The tensile strength of the polyamide resin composition can be adjusted depending on the composition. For example, by including the fatty acid metal salt (B) and the lubricant (C), the decrease in tensile strength can be further reduced.

The polyamide resin composition has high melt fluidity while maintaining excellent heat resistance and high tensile strength. Therefore, the above polyamide resin composition can be particularly preferably used for automotive parts, preferably automotive cooling parts.

1-6. Manufacturing method The above polyamide resin composition is prepared by mixing the polyamide resin (A), fatty acid metal salt (B), lubricant (C), and other components as necessary using a known resin kneading method, such as a Henschel mixer, a V blender, or a ribbon. It can be produced by mixing in a blender or tumbler blender, or by melt-kneading in a single-screw extruder, multi-screw extruder, kneader, or Banbury mixer, followed by granulation or pulverization.

In addition, when the lubricant (C) is composed of multiple components, the multiple components may be directly melt-kneaded together with other components other than the lubricant (C); or the multiple components may be melt-kneaded in advance. After pelletizing, the pellets may be melt-kneaded with other ingredients. Among these, from the viewpoint of making it easier to disperse the aliphatic diamide (C1), it is preferable to melt-knead the plurality of components in advance and pelletize them, and then melt-knead them together with other components other than the lubricant (C).

2. Molded object The above polyamide composition can be molded into various molded objects by known molding methods such as compression molding, injection molding, and extrusion molding.

A molded article of the above-mentioned polyamide composition can be used for various purposes. Among them, the polyamide resin composition of the present disclosure has high heat resistance and tensile strength, and is therefore particularly suitable as an automobile part. Examples of automotive parts include automotive cooling system parts such as radiator tank parts, coolant reserve tanks, water inlet pipes, water outlet pipes, water pump housings, water pump parts such as water pump impellers, water valves, etc.

Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the scope of the present disclosure is not limited to the description of the Examples.

1. Materials of resin composition 1-1. Polyamide resin (A)
(Preparation of polyamide resin 1)
Terephthalic acid 2774g (16.7mol), isophthalic acid 1196g (7.2mol), 1,6-hexanediamine 2800g (24.3mol), benzoic acid 36.6g (0.3mol), hypophosphorous acid 5.7 g of sodium monohydrate and 545 g of distilled water were placed in an autoclave having an internal capacity of 13.6 L, and the autoclave was purged with nitrogen. Stirring was started at 190°C, and the internal temperature was raised to 250°C over 3 hours. At this time, the internal pressure of the autoclave was increased to 3.03 MPa. After continuing the reaction for 1 hour, the low condensate was extracted by releasing it into the atmosphere from a spray nozzle installed at the bottom of the autoclave. Thereafter, after cooling the low condensate to room temperature, the low condensate was pulverized to a particle size of 1.5 mm or less using a pulverizer, and dried at 110° C. for 24 hours. The water content of the obtained low condensate was 4100 ppm, and the intrinsic viscosity [η] was 0.15 dl/g.

Next, this low condensate was placed in a plated solid phase polymerization apparatus, and after nitrogen purging, the temperature was raised to 180° C. over about 1 hour and 30 minutes. Thereafter, the reaction was carried out for 1 hour and 30 minutes, and the temperature was lowered to room temperature. The intrinsic viscosity [η] of the obtained prepolymer was 0.20 dl/g. Thereafter, this prepolymer was melt-polymerized in a twin-screw extruder with a screw diameter of 30 mm and L/D = 36 at a barrel temperature of 330°C, a screw rotation speed of 200 rpm, and a resin supply rate of 6 kg/h to produce polyamide. Resin (a-1) was prepared. The melting point (Tm) of the obtained polyamide resin was 330°C, and the glass transition temperature (Tg) was 125°C.

The melting point, glass transition temperature, and intrinsic viscosity [η] of the polyamide resin were measured by the following methods.

(Melting point Tm, glass transition temperature Tg)
The melting point (Tm) and glass transition temperature (Tg) of the polyamide resin were measured using a differential scanning calorimeter model DSC220C, manufactured by Seiko Instruments Inc. Specifically, about 5 mg of polyamide resin was sealed in an aluminum pan for measurement, and heated from room temperature to 350°C at a rate of 10°C/min. To completely melt the resin, it was held at 350°C for 3 minutes and then cooled to 30°C at 10°C/min. After leaving it at 30°C for 5 minutes, it was heated a second time to 350°C at 10°C/min. The temperature (°C) of the endothermic peak in this second heating was defined as the melting point (Tm) of the polyamide resin, and the displacement point corresponding to the glass transition was defined as the glass transition temperature (Tg).

(Intrinsic viscosity [η])
0.5 g of polyamide resin was dissolved in 50 ml of 96.5% sulfuric acid solution. The number of seconds of flow of the obtained solution under the condition of 25° C.±0.05° C. was measured using an Ubbelohde viscometer. Thereafter, the intrinsic viscosity was calculated based on the following formula.
[η]=ηSP/(C(1+0.205ηSP))
[η]: Intrinsic viscosity (dl/g)
ηSP: Specific viscosity C: Sample concentration (g/dl)
ηSP was determined by the following formula.
ηSP=(t-t0)/t0
t: Number of seconds for sample solution to flow down (seconds)
t0: Number of seconds for blank sulfuric acid flow (seconds)

1-2. Fatty acid metal salt (B)
・Sodium montanate (NS-8 manufactured by Nitto Kasei Kogyo Co., Ltd., melting point 200-220°C)

1-3. Lubricant (C)
(1) Components - Aliphatic diamide (C1)
Ethylene bisstearamide: Manufactured by Wako Pure Chemical Industries, Ltd. ・Low density polyethylene (C2)
Low density polyethylene 1: manufactured by NUC Corporation, NUC8008 (density: 918 kg/m ³ , melting point: 108°C, MFR: 4.7 g/10 minutes)
・Copolymer (C3)
Ethylene-n-butyl acrylate copolymer 1: Arkema Corporation 35BA320 (n-butyl acrylate content: 26 to 35% by mass, melting point: 65°C, MFR: 32 to 37 g/10 minutes @ 2.16 kg load, 190 ℃)
・Aromatic carboxylic acid compound (C4)
Terephthalic acid: manufactured by Wako Pure Chemical Industries, Ltd.

(2) Preparation of lubricant Low-density polyethylene 1: 720 g, ethylene bisstearamide: 1440 g, terephthalic acid: 400 g, ethylene-n-butyl acrylate copolymer 1: 1440 g were mixed in a tumbler blender, and a twin-screw extruder ( The mixture was melted and kneaded using a TEX30α (manufactured by Japan Steel Works, Ltd.) at a cylinder temperature of 230°C. Thereafter, it was extruded into strands and cooled in a water bath. Thereafter, the strands were taken up with a pelletizer and cut to obtain a pelletized lubricant.

1-4. Reinforcement material (D)
Glass fiber (manufactured by Nittobo Co., Ltd., CSX3J-451)

2. Preparation of polyamide resin composition (Example 1, Comparative Examples 1 to 5)
The components shown in Table 1 were mixed in a tumbler blender at the compounding ratio shown in the table, and then heated in a twin-screw extruder (TEX30α manufactured by Japan Steel Works) at a cylinder temperature (melting point of polyamide resin (A) (Tm)). )+15)°C and melt-kneaded. Thereafter, it was extruded into strands and cooled in a water bath. Thereafter, the strands were taken up with a pelletizer and cut to obtain a pellet-shaped polyamide resin composition.

(evaluation)
(1) Fluidity Injection molding was performed under the following conditions using a barflow mold with a width of 10 mm and a thickness of 0.5 mm, and the flow length (mm) of the resin in the mold was measured.
Injection molding machine: Tupar TR40S3A (manufactured by Sodick Plastech)
Injection setting pressure: 2000kg/ ^cm2
Cylinder setting temperature: 335℃

(2) Tensile Strength The obtained polyamide resin composition was molded using the following injection molding machine under the following molding conditions to obtain an ASTM dumbbell-shaped test piece Type I having a thickness of 3.2 mm.
(Molding condition)
Molding machine: SG50M3 manufactured by Sumitomo Heavy Industries
Molding machine cylinder temperature: 340℃
Mold temperature: 120℃
Injection setting speed: 60mm/sec
The obtained test piece was left at a temperature of 23°C under a nitrogen atmosphere for 24 hours. Next, a tensile test was conducted in accordance with ASTM D638 in an atmosphere of a temperature of 23° C. and a relative humidity of 50% to measure the tensile strength.

The evaluation results of Examples 1 to 2 and Comparative Examples 1 to 5 are shown in Table 1.

As shown in Table 1, the polyamide resin composition of Example 1 containing a fatty acid metal salt (B) and an aliphatic diamide (C1) contained one of the fatty acid metal salt (B) and the aliphatic diamide (C1). It can be seen that the fluidity can be significantly improved while minimizing the decrease in tensile strength, compared to the polyamide resin compositions of Comparative Examples 1 to 5 containing only the polyamide resin compositions. In particular, the fluidity is higher than expected from the polyamide resin composition of Comparative Example 2 using only the fatty acid metal salt (B) and the polyamide resin composition of Comparative Example 4 using only the aliphatic diamide (C2). It showed liquidity at the level.

The polyamide resin composition of the present disclosure can suppress a decrease in tensile strength of the polyamide resin composition while improving fluidity during injection molding. Therefore, it can be used in automobile cooling system parts etc. that are required to have particularly high strength. It can be suitably used.

Claims (15)

A polyamide resin (A) having a melting point of 280° C. or higher as measured by differential scanning calorimetry (DSC);
0.1 to 30 parts by mass of fatty acid metal salt (B) based on 100 parts by mass of the polyamide resin (A),
0.1 to 30 parts by mass of a lubricant (C) per 100 parts by mass of the polyamide resin (A),
including;
The polyamide resin (A) contains a structural unit derived from a dicarboxylic acid and a structural unit derived from a diamine,
The structural units derived from the dicarboxylic acid include 20 to 100 mol% of structural units derived from terephthalic acid and 0 to 80 mol% of structural units other than terephthalic acid, based on the total number of moles of the structural units derived from the dicarboxylic acid. Contains a structural unit derived from an aromatic dicarboxylic acid,
The structural unit derived from the diamine includes at least one of a structural unit derived from an aliphatic diamine and a structural unit derived from an alicyclic diamine,
The lubricant (C) is
Contains an aliphatic diamide (C1) obtained by reacting a saturated aliphatic monocarboxylic acid whose main chain has 10 to 30 carbon atoms and an aliphatic diamine whose main chain has 2 to 12 carbon atoms.
Polyamide resin composition. The lubricant (C) further contains low density polyethylene (C2),
The polyamide resin composition according to claim 1. The lubricant (C) further includes a copolymer (C3) containing a structural unit derived from an olefin and a structural unit derived from an α,β-unsaturated carboxylic acid ester.
The polyamide resin composition according to claim 1 or 2. The lubricant (C) further contains an aromatic carboxylic acid compound (C4),
The polyamide resin composition according to any one of claims 1 to 3. The lubricant (C) is
For 100 parts by mass of the lubricant,
10 to 79.5 parts by mass of the aliphatic diamide (C1),
10 to 79.5 parts by mass of low density polyethylene (C2),
10 to 79.5 parts by mass of a copolymer (C3) containing a structural unit derived from an olefin and a structural unit derived from an α,β-unsaturated carboxylic acid ester,
0.5 to 20 parts by mass of aromatic carboxylic acid compound (C4),
including,
The polyamide resin composition according to any one of claims 1 to 4. The aliphatic diamide (C1) is ethylene bisstearamide,
The polyamide resin composition according to any one of claims 1 to 5. The copolymer (C3) is a copolymer containing a structural unit derived from ethylene and a structural unit derived from a C1-10 acrylic acid alkyl ester.
The polyamide resin composition according to claim 3. The copolymer (C3) contains one or more of ethylene/n-butyl acrylate copolymer, ethylene/methyl acrylate copolymer, and ethylene/ethyl acrylate copolymer,
The polyamide resin composition according to claim 7. The aromatic carboxylic acid compound (C4) is terephthalic acid,
The polyamide resin composition according to claim 4. The content ratio (C/B) of the lubricant (C) and fatty acid metal salt (B) is 0.1 to 10 (mass ratio),
The polyamide resin composition according to any one of claims 1 to 9. Further comprising 1 to 300 parts by mass of glass fiber (D) based on 100 parts by mass of the polyamide resin (A),
The polyamide resin composition according to any one of claims 1 to 10. The glass transition temperature of the polyamide resin (A) measured by differential scanning calorimetry (DSC) is 100 to 145°C.
The polyamide resin composition according to any one of claims 1 to 11. The tensile strength of the polyamide resin composition measured according to ASTM D638 is 205 MPa or more,
The polyamide resin composition according to any one of claims 1 to 12. Comprising the polyamide resin composition according to any one of claims 1 to 13,
Molded object. Used in automotive cooling system parts.
The molded article according to claim 14.