JP2013043976A - Polyamide resin composition and molded product prepared by molding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition which has a low density and improved moldability as well as mechanical properties, is capable of shortening a molding cycle, inhibiting contamination of a deteriorated resin product and a decomposition gas, and providing a molded product excellent in appearance, is excellent in mass productivity since the molding cycle is shortened, and has significantly excellent moldability for molding components subjected to mass production with homogenized quality.SOLUTION: The polyamide resin composition comprises: 100 pts.mass of a polyamide resin containing a terephthalic acid component and a 8-12C straight-chain aliphatic diamine component; and 0.5 to 20 pts.mass of a swelling layer silicate.

Description

  The present invention relates to a polyamide resin composition having improved moldability in addition to mechanical properties.

Semi-aromatic polyamides typified by polyamide 6T and polyamide 9T are excellent in heat absorption and mechanical properties, as well as low water absorption, and are used as many electrical / electronic parts and parts around automobile engines.
On the other hand, high heat-resistant materials represented by polyimide and liquid crystal polyester are used as substrate materials for electric and electronic parts. However, although such a material is very excellent in terms of performance, it is very expensive and inferior in processability. Therefore, the use of the semi-aromatic polyamide for such applications has been studied.
Since the melting point of the homopolymer of the polyamide 6T is too high at 370 ° C., the thermal decomposition of the polyamide 6T at the time of melt processing cannot be suppressed. Therefore, the polyamide 6T is used in a state where the melting point is sufficiently lowered by introducing a large amount of copolymer components. However, such copolymerized polyamide 6T has a loss of crystallinity and cannot accelerate crystallization.

Patent Document 1 discloses a polyamide molded body containing glass fibers with respect to polyamide 10T. However, such a molded body cannot obtain the required mechanical properties unless a large amount of glass fiber is used. On the other hand, the contained glass fiber impairs the fluidity at the time of molding and has a problem in moldability.
Patent Document 2 discloses a polyamide composition containing a layered silicate composed of an organic clay with respect to polyamide 6T / 10T. Although such a polyamide composition was able to improve the fluidity at the time of molding than the composition containing the glass fiber, it takes a long time to crystallize, so that it is short when injection molding is performed. A polyamide resin composition in which the crystallization was sufficiently accelerated and the molding cycle was shortened until it was possible to take out from the mold in time was not obtained.

JP-A-6-239990 JP 2010-159414 A

  An object of the present invention is to provide a polyamide resin composition having low specific gravity and improved moldability in addition to mechanical properties.

  The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.

  That is, the gist of the present invention is as follows.

(1) A polyamide resin composition comprising 100 parts by mass of a polyamide resin comprising a terephthalic acid component and a linear aliphatic diamine component having 8 to 12 carbon atoms, and 0.5 to 20 parts by mass of a swellable layered silicate.
(2) The polyamide resin composition according to (1), wherein 0.5 to 30 parts by mass of a compound having an amino group is inserted between 100 parts by mass of the swellable layered silicate.
(3) The polyamide resin composition according to (1) or (2), wherein the swellable layered silicate is at least one selected from swellable fluoromica, montmorillonite, and hectorite.
(4) The method for producing a polyamide resin composition according to any one of (1) to (3), wherein a compound having an amino group is inserted between layers of the swellable layered silicate and then melt mixed with the polyamide resin.
(5) A molded product obtained by molding the polyamide resin composition of (1) to (4).

According to the present invention, it is possible to provide a polyamide resin composition having low specific gravity and improved moldability in addition to mechanical properties.

Hereinafter, the present invention will be described in detail. The polyamide resin used in the present invention is a polyamide comprising a dicarboxylic acid component and a diamine component. In the present invention, it is necessary to use a dicarboxylic acid component and a diamine component having a specific chemical structure from the viewpoint of high crystallinity.
The dicarboxylic acid component constituting the polyamide resin needs to use terephthalic acid as a main component. The reason is that terephthalic acid is most preferable for obtaining a polyamide resin having high crystallinity and high crystallinity among aromatic dicarboxylic acids.
The diamine component constituting the polyamide resin needs to be a linear aliphatic diamine having 8 to 12 carbon atoms from the viewpoint of the melt processability of the resulting polyamide, and any one of the diamines is preferably used alone. Further, 1,8-octanediamine, 1,10-decanediamine, and 1,12-dodecanediamine are preferable for obtaining a polyamide resin having high crystallinity because of high symmetry of the chemical structure.

  The reason why the diamine used must have an even number of carbon atoms will be described below. In general, a so-called even-odd effect appears in polyamide. That is, when the number of carbon atoms in the monomer unit of the diamine component used is an even number, a more stable crystal structure is formed as compared with the case where the number is an odd number, so that the effect of improving crystallinity is exhibited. Therefore, from the viewpoint of high crystallinity, the linear aliphatic diamine needs to have an even number of carbon atoms.

  When the number of carbon atoms of the diamine is less than 8, the melting point of the obtained polyamide resin exceeds 340 ° C. and exceeds the decomposition temperature, which is not preferable. On the other hand, when the number of carbon atoms of the diamine exceeds 12, the melting point of the obtained polyamide resin is less than 280 ° C., which is not preferable because the heat resistance is insufficient in practical use. The diamine having 9 or 11 carbon atoms lacks crystallinity due to the even-odd effect of polyamide.

  The polyamide resin used in the present invention includes a dicarboxylic acid component other than a terephthalic acid component as a main component and / or a diamine component of a type other than a linear aliphatic diamine component having 8 to 12 carbon atoms (hereinafter referred to as “co-polymer”). May be referred to as “polymerization component”). The copolymer component is preferably 5 mol% or less with respect to the total number of moles of raw material monomers (100 mol%), and more preferably substantially free of the copolymer component. This is because, from the viewpoint of high crystallinity, it is preferable to have a structure close to a homopolymer having high regularity rather than a copolymer having an irregular chemical structure. That is, when the copolymerization component exceeds 5 mol%, the crystallinity is lowered and a polyamide resin having high crystallinity may not be obtained.

  Examples of dicarboxylic acid components other than terephthalic acid that can be used as a copolymer component for polyamide resins include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane Examples thereof include aliphatic dicarboxylic acids such as diacid and dodecanedioic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid.

  Other diamine components that can be used as the copolymer component of the polyamide resin include 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6 -Aliphatic diamines such as hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, Examples include alicyclic diamines such as cyclohexanediamine and aromatic diamines such as xylylenediamine. When any one of 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine is used as an essential diamine component, otherwise The diamine component can be used as a copolymerization component.

  If necessary, the polyamide resin may be copolymerized with lactams such as caprolactam.

  The weight average molecular weight of the polyamide resin is preferably 15,000 to 50,000, more preferably 20,000 to 50,000, and further preferably 26,000 to 50,000. When the weight average molecular weight of the polyamide resin is less than 15,000, crystallization of the obtained polyamide resin is accelerated, but the rigidity is lowered. When the weight average molecular weight of the polyamide resin exceeds 50,000, crystallization is slowed down and the fluidity at the time of injection molding is lowered.

  The relative viscosity of the polyamide resin is not particularly limited, and may be appropriately set depending on the purpose. For example, in order to obtain a polyamide resin that can be easily molded, the relative viscosity is preferably 2.0 or more.

  The polyamide resin used in the present invention preferably has a sufficiently reduced triamine amount. The polyamide resin tends to have a triamine structure as a by-product due to a condensation reaction between diamines during polymerization. When the amount of triamine is large, a crosslinked structure is formed in the molecular chain, and the crosslinked structure restricts the movement and arrangement of the molecular chain, so that the crystallinity is lowered. Further, when the amount of triamine is large, a large amount of gel is generated, so that it may be present as fish eyes or irregularities on the surface of the obtained molded body, which may cause a deterioration of the surface appearance.

  Therefore, the triamine unit contained in the polyamide resin needs to be 0.3 mol% or less of the diamine unit, and preferably 0.2 mol% or less. When the triamine structure in the polyamide resin exceeds 0.3 mol% of the diamine unit, the crystallinity is lowered, the surface smoothness of the molded product obtained by generating a gel is impaired, and the color tone is reduced. Problems may develop. Setting the triamine unit contained in the polyamide resin to 0.3 mol% or less of the diamine unit can improve the viscosity characteristics of the polyamide resin. That is, the fluidity at the time of melting can be improved and the moldability can be improved.

  In order to make the above-mentioned triamine unit 0.3 mol% or less of the diamine unit, when the salt is formed from the terephthalic acid component and the diamine component, the blending amount of water and organic solvent is 100 parts by mass in total of the raw material monomers. It is necessary that the amount be 5 parts by mass or less.

  In general, in order to allow the heat polymerization reaction of polyamide to proceed uniformly, a method is used in which raw materials are mixed in the presence of water and heated to advance the dehydration reaction. However, in such a method, when the total amount of water and the organic solvent during polymerization is more than 5 parts by mass with respect to 100 parts by mass of the raw material monomers, an increase in the degree of polymerization is suppressed. There is. In that case, the residence time in the polymerization apparatus in a state where there are many amine ends becomes longer, and the amount of triamine by-produced by the condensation reaction between diamines increases. As a result, a part of the polyamide takes a crosslinked structure, and gelation is promoted or the color tone is lowered. Gelation causes a decrease in the crystallinity of the polyamide and delays the crystallization rate. And in the semi-aromatic polyamide like this invention, the production | generation of a triamine is more remarkable than an aliphatic polyamide. Therefore, as in the present invention, in order to obtain a polyamide resin in which the triamine unit is 0.3 mol% or less of the diamine unit, the blending amount of water or an organic solvent is 5 with respect to a total of 100 parts by mass of the raw material monomers. It is necessary that the amount is not more than part by mass, and it is more preferable that water is not substantially mixed.

  The swellable layered silicate used in the present invention may be a naturally occurring one, or an artificially synthesized or modified one. , Mica (fluorine mica, muscovite, paragonite, phlogopite, lepidrite) Etc.). These swellable layered silicates may be used in combination of two or more. In particular, swellable fluoromica, montmorillonite and hectorite are preferably used because of their availability.

  There is no particular limitation on the initial particle size of the swellable layered silicate. Here, the initial particle size is the particle size of the swellable layered silicate as a raw material to be used, and is different from the size of the silicate layer in the polyamide resin composition. However, this particle size also has a considerable influence on the physical properties of the obtained polyamide resin composition, in particular, rigidity and heat resistance. Therefore, it is desirable to take this point into consideration when selecting the mixing ratio of the above-mentioned swellable layered silicate, and it is preferable to control the particle size by pulverizing with a jet mill or the like as necessary.

  In the swellable layered silicate used in the present invention, a compound having an amino group is preferably inserted between the layers. Examples of the compound having an amino group include aminocarboxylic acids such as 12-aminododecanoic acid, 11-aminoundecanoic acid, and 6-aminocaproic acid, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetra Aliphatic primary amines such as decylamine, pentadecylamine, stearylamine, oleylamine and the like can be mentioned. By dissolving the halogenated salt or metal salt of these amines in pure water, mixing a predetermined amount of swellable layered silicate into the solution, stirring at room temperature, filtering and drying, A swellable layered silicate having these amine cations inserted between the layers can be obtained.

  When inserting the compound which has an amino group between the layers of swellable layered silicate, it is preferable to set it as 0.5-30 mass parts with respect to swellable layered silicate. When the amount is less than 0.5 parts by mass, the interlayer of the swellable layered silicate is not sufficiently expanded, the dispersibility is insufficient, and the effect of improving the bending strength of the resulting polyamide resin composition is poor, and more than 30 parts by mass In the case of, the reaction between the layers of the swellable lamellar silicate does not occur any more, and when the compound having an unreacted amino group is mixed with the polyamide resin, the mechanical properties of the polyamide resin composition are lowered. This is not preferable because it causes

  The polyamide resin composition of the present invention must contain 0.5 to 20 parts by mass of the swellable layered silicate with respect to 100 parts by mass of the polyamide resin, preferably 0.8 to 15 parts by mass. Most preferably, it is 10 parts by mass. When the blending amount of the swellable layered silicate is less than 0.5 parts by mass, the effect of improving the bending strength, the flexural modulus, and the deflection temperature under load is small, and when it exceeds 20 parts by mass, the workability during melt-kneading is reduced. In addition, it becomes difficult to obtain a pellet of the polyamide resin composition. The use of the swellable layered silicate in an amount of 0.5 to 20 parts by mass with respect to 100 parts by mass of the polyamide resin not only effectively improves the bending strength, flexural modulus, and deflection temperature under load, but also melts. The fluidity at the time can be improved and the moldability can be improved.

  Since the polyamide resin composition of the present invention is intended to accelerate crystallization and improve moldability, the crystallization rate needs to be controlled within a specific range. In the present invention, the crystallization rate can be determined by using the degree of supercooling ΔT measured using a differential scanning calorimeter (DSC) as an index, and ΔT needs to be 40 ° C. or less, and is 35 ° C. or less. Is preferred. If ΔT exceeds 40 ° C, the crystallinity cannot be sufficiently increased, the molding cycle cannot be shortened, and it is difficult to release from the mold, resulting in a decrease in continuous productivity during molding. There are things to do.

In the present invention, as shown in the following formula, the degree of supercooling ΔT is the melting point of the polyamide resin composition (hereinafter sometimes abbreviated as Tm) and the cooling crystallization temperature (hereinafter abbreviated as Tcc). Is defined as the difference.
ΔT = Tm-Tcc
In the above formula, the polyamide resin composition is cooled from the molten state to 25 ° C. at a temperature decreasing rate of 20 ° C./min under an inert gas atmosphere using a differential scanning calorimeter (DSC), and then 20 ° C./min. The temperature of the endothermic peak that appears when the temperature is raised at the rate of temperature rise is defined as the melting point (Tm). Similarly, the temperature of the exothermic peak that appears when the temperature is lowered from the molten state to 25 ° C. at a temperature lowering rate of 20 ° C./min is defined as the temperature-falling crystallization temperature (Tcc). The smaller ΔT, the faster the crystallization from the molten state of the polyamide resin composition.

By satisfying the range of ΔT of 40 ° C. or less and the reinforcing effect of the molded body by the swellable layered silicate, the rigidity of the molded body at the time of taking out from the mold at the time of injection molding is increased. Compared to a polyamide resin molded body that does not contain, the molded body can be taken out from the mold even if the cooling time is shortened. Therefore, it is possible to shorten the time required to form one molded body by injection molding (hereinafter referred to as a molding cycle). This not only improves the production efficiency of the molded body, but also makes it possible to shorten the residence time of the resin staying in the cylinder of the injection molding machine, particularly when performing continuous injection molding. It is possible to suppress deterioration and generation of decomposition gas, to suppress the above-mentioned deteriorated product, decomposition gas, and mold contamination, and to improve the quality of the molded body. Suppression of mold contamination improves mold release at the time of taking out from the mold, and it can maintain good mold release performance continuously. Therefore, mold release failure when performing automatic molding on production lines etc. Continuous productivity capable of continuous molding for a long time can be improved without causing the operation to stop.
In the case of the polyamide resin used in the present invention, when the melting point is higher than that of polyamide 6 and polyamide 66, the resin melting temperature for obtaining a molded body is high, and the resin stays in the molding machine cylinder for a long time. The deterioration of the resin and generation of decomposition gas become remarkable. Therefore, the molding cycle is shortened and the residence of the molten resin in the molding machine cylinder is suppressed as much as possible by molding the polyamide resin composition of the present invention. This is preferable in terms of the quality of a molded body and a molding handling surface for obtaining a molded body having excellent properties.

  A polyamide resin using a diamine component having an even number of carbon atoms has high crystallinity in the first place. In order to achieve further high crystallinity, as described above, the copolymerization component in the polyamide resin of the present invention can be 0 to 5 mol%. In order to achieve further high crystallinity, as described above, the triamine unit relative to the diamine unit in the polyamide resin may be 0.3 mol% or less.

  The polyamide resin used in the present invention can be produced by a conventionally known method for producing polyamide, such as a heat polymerization method or a solution polymerization method. Of these, the heat polymerization method is preferably used because it is industrially advantageous. Examples of the heat polymerization method include a melt polymerization method, a melt extrusion method, and a solid phase polymerization method. The polyamide resin has a high melting point of 280 ° C. to 340 ° C. and is close to the decomposition temperature. Therefore, the melt polymerization method or melt extrusion method in which the reaction is performed at a temperature equal to or higher than the melting point of the produced polymer may be inappropriate because the quality of the product may be deteriorated. Therefore, a solid phase polymerization method at a temperature below the melting point of the produced polymer is preferable.

  In general, the production of a polyamide resin often includes a step (i) of obtaining a reactant from a monomer and a step (ii) of polymerizing such a reactant. In the present invention, the triamine unit is a diamine unit. In order to obtain a polyamide having a content of 0.3 mol% or less, the step of step (i) is carried out under the condition that water and solvent in the polymerization system are low, that is, with respect to a total of 100 parts by mass of dicarboxylic acid and diamine. It is preferable to carry out in the presence of water and / or an organic solvent in which the total amount of the organic solvent is 5 parts by mass or less.

  As a specific example of the step (i), for example, a suspension composed of a molten diamine and a solid dicarboxylic acid is stirred and mixed to obtain a mixed solution, and then at a temperature lower than the melting point of the finally produced polyamide. And a method of obtaining a mixture of a salt and a low polymer by producing a salt by the reaction of a dicarboxylic acid and a diamine and a production reaction of a low polymer by polymerizing the salt. Since such a reaction product is usually in the form of a lump, a powdery reaction product can be obtained by crushing while reacting, or by taking out after the reaction and then crushing.

  As a specific example of the step (ii), for example, the reaction product obtained in the step (i) is solid-phase polymerized at a temperature lower than the melting point of the finally produced polyamide resin to increase the molecular weight to a predetermined molecular weight. And a step of obtaining a polyamide resin. The solid phase polymerization is preferably performed in a stream of inert gas such as nitrogen at a polymerization temperature of 180 to 270 ° C. and a reaction time of 0.5 to 10 hours.

  In the production of a polyamide resin, a polymerization catalyst can be used to increase the efficiency of polymerization, and an end-capping agent can be used to adjust the degree of polymerization, suppress thermal decomposition, and coloring.

  Examples of the polymerization catalyst include phosphoric acid, phosphorous acid, hypophosphorous acid or salts thereof. The addition amount of the polymerization catalyst is usually 0 to 2 mol relative to the total mol of dicarboxylic acid and diamine. % Is preferably used.

  Examples of the terminal blocking agent include monocarboxylic acids such as acetic acid, lauric acid, and benzoic acid, and monoamines such as octylamine, cyclohexylamine, and aniline, and any one of these or a combination thereof can be used. As the addition amount of the end capping agent, it is usually preferable to use 0 to 5% by mole based on the total moles of terephthalic acid and diamine.

  The method of blending the swellable layered silicate is not particularly limited, but melt kneading using a biaxial kneader is preferably used. The kneading temperature needs to be not less than the melting point (Tm) of the polyamide resin, and is preferably less than (Tm + 100 ° C.). If the kneading temperature is less than Tm, the kneader is overloaded, and problems such as vent-up may occur. If the kneading temperature is too high, the polyamide resin may be decomposed or yellowed. The method for collecting the obtained polyamide resin composition is not particularly limited, but it is preferable to produce a strand and pelletize it in consideration of subsequent molding. When a compound having an amino group is inserted between the layers of the swellable layered silicate, the dispersibility of the swellable layered silicate is particularly improved by sufficiently expanding the layer of the swellable layered silicate during melt kneading. It can be implemented preferably. As a method for obtaining such a swelled layered silicate, it is preferable that the swellable layered silicate is previously subjected to a swelling treatment using a compound having an amino group, and then the above melt kneading is performed.

  As a viscosity characteristic at the time of melting of the polyamide resin composition, a melt flow rate (hereinafter referred to as MFR) at 340 ° C. and 1.20 kg is preferably 0.1 to 50 g / 10 minutes, and preferably 1 to 40 g / 10. More preferably, it is 10 to 30 g / 10 minutes. By making MFR into the range of 0.1-50 g / 10min, the fluidity at the time of injection molding of the polyamide resin composition and the obtained molding cycle can be balanced. Furthermore, it is preferable because crystallization of the polyamide resin composition can be accelerated. If the MFR is less than 0.1 g / 10 minutes, the fluidity tends to be insufficient, and melt kneading and injection molding tend to be difficult. If the MFR exceeds 50 g / 10 minutes, the mechanical strength of the resulting molded body is improved. Becomes difficult. In order to obtain the above-mentioned viscosity characteristics, the triamine unit contained in the polyamide resin should be 0.3 mol% or less of the diamine unit, and the swellable layered silicate to be used should be added in an amount of 0.0. It can implement preferably by containing 5-20 mass parts.

  Examples of methods for molding using the polyamide resin composition include injection molding methods, extrusion molding methods, blow molding methods, etc., but in terms of sufficiently improving the moldability of the polyamide resin used in the present invention. The injection molding method can be preferably used. Although it does not specifically limit as an injection molding machine, For example, a screw in-line type injection molding machine or a plunger type injection molding machine etc. are mentioned. The polyamide resin composition heated and melted in the cylinder of the injection molding machine is weighed for each shot, injected into the mold in a molten state, cooled to a predetermined shape and solidified, and then as a molded body from the mold. It is taken out. The resin temperature at the time of injection molding must be heated and melted at a melting point (Tm) or higher of the polyamide resin, and is preferably less than (Tm + 100 ° C.). In addition, when the polyamide resin composition is heated and melted, it is preferable to use a sufficiently dried polyamide resin composition pellet. If the water content is large, the resin foams in the cylinder of the injection molding machine, and it may be difficult to obtain an optimal molded body. The moisture content of the polyamide resin composition pellets used for injection molding is preferably less than 0.3% by mass and more preferably less than 0.1% by mass in 100% by mass of the polyamide resin composition.

  When injection molding the polyamide resin composition used in the present invention, the mold temperature must be kept below the glass transition temperature (Tg) of the polyamide resin composition, and is preferably less than (Tg-30 ° C), More preferably, it is less than (Tg-50 degreeC). When the mold temperature exceeds the Tg of the polyamide resin composition, the effect of improving the mechanical properties due to the swellable layered silicate blend of the polyamide resin cannot be sufficiently obtained. The mold temperature is the actual temperature of the mold dividing surface, and is adjusted using a mold temperature controller so that this portion is within the above temperature range. You may circulate a refrigerant | coolant in a metal mold | die as needed.

  You may add additives, such as another filler and a stabilizer, to the polyamide resin composition of this invention as needed. Examples of the method of addition include addition at the time of polymerization of polyamide, or melt kneading to the obtained polyamide resin composition. Additives include fillers such as talc, silica, alumina, glass beads, graphite, pigments such as titanium oxide, carbon black, etc., antioxidants, antistatic agents, flame retardants, flame retardant aids, etc. Well-known additives are mentioned.

  The polyamide resin composition of the present invention is particularly preferably used in molding applications and can be formed into a molded body. In order to produce a molded body from the polyamide resin composition of the present invention, a normal molding method is used. Examples of the molding method include hot melt molding methods such as injection molding, extrusion molding, blow molding, and sintering molding. By such a method, various molded articles can be obtained.

In the polyamide resin composition of the present invention, ΔT measured using a differential scanning calorimeter (DSC) satisfies the range of 40 ° C. or less, and the crystallization speed is high. Can be shortened, which can contribute to a reduction in molding cost.
The molding cycle refers to the time from the start of the injection of the first shot of the molded body to the start of the injection of the second shot of the molded body when continuously molded under the same injection conditions. That is, it refers to the time required to mold one molded body (total of injection time + cooling time + removal time). The shortening of the molding cycle means a shortening of the cooling time during the time required for molding the one molded body.

Since the polyamide resin composition of the present invention is excellent in moldability in addition to the mechanical strength that has been provided so far, it can be used in a wide range of applications such as automobile parts, electrical and electronic parts, sundries, and civil engineering and building supplies.
Especially, it can be used for durable consumer goods by making use of the reinforcing effect of the swellable layered silicate, and can be suitably used for automobile parts and electrical / electronic parts.
In automotive parts applications, engine covers, air intake manifolds, throttle bodies, air intake pipes, radiator tanks, radiator supports, radiator hoses, radiator grills, timing belt covers, water pump renlets, water pump outlets, cooling fans, fan shrouds Engine peripheral parts such as engine mount, propeller shaft, stabilizer bar linkage rod, accelerator pedal, pedal module, seal ring, bearing retainer, gear and other mechanical parts, oil pan, oil filter housing, oil filter cap, oil level gauge, Fuel tank, fuel tube, fuel cutoff valve, canister, fuel delivery pipe, fuel -Fuel filler and piping system parts such as L filler neck, fuel sender module, fuel pipe joint, wire harness, relay block, sensor housing, encapsulation, ignition coil, distributor, thermostat housing, quick connector, lamp reflector, Electrical parts such as lamp housing, lamp extension, lamp socket, rear spoiler, wheel cover, wheel cap, cowl vent grill, air outlet louver, air scoop, hood bulge, fender, back door, shift lever housing, window regulator, It can be suitably used for various interior and exterior parts such as door locks, door handles, and outside door mirror stays.
In electrical / electronic component applications, connectors, LED reflectors, switches, sensors, sockets, capacitors, jacks, fuse holders, relays, coil bobbins, resistors, ICs, LED housings, and the like can be given.
Since these automobile parts and electrical / electronic parts are mainly molded by injection molding and blow molding, when the polyamide resin composition of the present invention is used, the molding cycle is shortened, and resin degradation products and decomposition gas are mixed. Can be obtained, and a molded article excellent in appearance can be obtained. In addition, since the molding cycle is shortened, it is excellent in mass productivity, and has a remarkably excellent moldability in the molding of parts that are produced in large quantities with uniform quality.

1. Measurement Method Resin performance was evaluated according to the following method.

(1) Relative Viscosity of Polyamide Resin Measured at a concentration of 1 g / dL and 25 ° C. using 96 mass% sulfuric acid as a solvent.

(2) Weight average molecular weight of polyamide resin Using a gel permeation chromatography apparatus manufactured by Tosoh Corporation, GPC analysis was performed using a sample solution adjusted under the following conditions, and then polymethyl methacrylate (manufactured by Polymer Laboratories) was prepared as a standard sample. The weight average molecular weight was determined using a calibration curve.
<Sample preparation>
2 ml of hexafluoroisopropanol containing 10 mM sodium trifluoroacetate was added to 5 mg of polyamide resin and dissolved, followed by filtration with a disk filter.
<Conditions>
・ Detector: Differential refractive index detector RI-8010 (manufactured by Tosoh Corporation)
Eluent: Hexafluoroisopropanol containing 10 mM sodium trifluoroacetate Flow rate: 0.4 ml / min
・ Temperature: 40 ℃

(3) Decreasing crystallization temperature, melting point and degree of supercooling of polyamide resin Using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer Co., Ltd., the temperature was raised to 350 ° C. at a rate of temperature increase of 20 ° C./min. Hold for 5 minutes, the temperature giving the top of the exothermic peak when the temperature is lowered to 25 ° C. at a temperature drop rate of 20 ° C./min is the temperature drop crystallization temperature (Tcc). The top of the endothermic peak when the temperature rise was measured at / min was defined as the melting point (Tm). The difference between the melting point and the cooling crystallization temperature (Tm−Tcc) was defined as the degree of supercooling (ΔT).

(4) Determination of triamine in polyamide resin 3 mL of 47% hydrobromic acid is added to 10 mg of polyamide resin, heated at 130 ° C. for 20 hours, evaporated to dryness, and further dried under reduced pressure at 80 ° C. for 2 hours. To this, 2 mL of pyridine and 1 mL of N, O-bis (trimethylsilyl) trifluoroacetamide are added and heated at 90 ° C. for 30 minutes. After cooling, the solution filtered with a membrane filter was analyzed with a gas chromatography apparatus equipped with a mass spectrometer. Using a calibration curve obtained from diamine and triamine as standard substances separately measured, diamine and triamine in the polyamide resin were quantified, and the molar ratio of triamine to diamine was calculated. As a triamine standard substance, a triamine compound obtained by reacting diamine with heating and stirring at 240 ° C. for 3 hours in an autoclave using palladium oxide as a catalyst was used.

(5) Specific gravity of polyamide resin composition 1 g of the resin pellet of the polyamide resin composition was prepared, and measured by a gas substitution type pinometer method using a dry automatic densimeter (Acupic II 134 type manufactured by Shimadzu Corporation).

(6) Melt flow rate (MFR) of polyamide resin composition
According to JIS K7210, the measurement was performed using a polyamide resin composition pellet at 340 ° C. and a load of 1.2 kgf. The unit is g / 10 minutes.

(7) Flexural strength and flexural modulus of polyamide resin composition Measured according to ASTM D790.

(8) Deflection temperature under load of polyamide resin composition Based on ASTM D648, it was measured at a load of 1.8 MPa.

(9) Moldability After setting the cylinder temperature (melting point + 25 ° C.) and the mold temperature (melting point−185 ° C.) using an injection molding machine EC-100 manufactured by Toshiba Machine Co., Ltd., injection pressure 100 MPa, injection time 10 The molded body (127 mm × 12.7 mm × 10 mm) was molded with a second and a removal time of 5 seconds.
(9-1) Molding cycle The molded body was molded. The shortest cooling time that can be easily taken out without deforming the compact with the protruding pin was measured. Here, the molding cycle refers to the time from the start of the injection of the first shot of the molded body to the start of the injection of the second shot of the molded body when continuously molded under the same injection conditions. That is, it refers to the time required to mold one molded body (total of injection time + cooling time + removal time). This molding cycle is preferably 30 seconds or less, and more preferably 25 seconds or less.
(9-2) Continuous Productivity The molded body was continuously molded according to the molding cycle obtained in (9-1) (maximum 100). At the time of taking out the molded body from the mold, the number of the molded bodies that could be taken out up to the number of times that smooth removal without the deformation of the molded body by the protruding pin was possible was counted. 90 or more are preferable, and 95 or more are more preferable.

2. Raw materials The raw materials used in Examples and Comparative Examples are shown below.
(1) Dicarboxylic acid component, terephthalic acid, isophthalic acid (2) Diamine component, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine (3) Swellable layered Silicate swellable fluorinated mica (trade name “ME-100” manufactured by Coop Chemical Co., Ltd.)
・ Montmorillonite (Kunipia, trade name “Kunipia F”)
-Hectorite (product name "Bentone HC", manufactured by Elementis Specialties)
(4) Interlayer treatment agent, stearylamine (made by Showa Chemical Co., Ltd.)
・ 6-Aminocaproic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
Silane coupling agent: 3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.)
(5) Filler / glass fiber (03JAFT692 manufactured by Asahi Fiber Glass Co., Ltd.), average fiber diameter 10 μm, average fiber length 3 mm
Carbon fiber (HTA-C6-NR manufactured by Toho Tenax Co., Ltd.), average fiber diameter 7 μm, average fiber length 6 mm
・ Talc (Nippon Talc Microace K-1), average particle diameter 7.4 μm

Production Example 1
[Step (i)]
1,10-decanediamine (5050 parts by mass) as a diamine component, powdered terephthalic acid (4870 parts by mass) with an average particle size of 80 μm, benzoic acid (72 parts by mass) as a terminal blocking agent, and sodium hypophosphite as a polymerization catalyst The monohydrate (6 parts by mass) was placed in an autoclave, heated to 100 ° C., stirred using a double helical type stirring blade at a rotation speed of 28 rpm, and heated for 1 hour. The molar ratio of the raw material monomers was 1,10-decanediamine: terephthalic acid = 50: 50. The mixture was heated to 230 ° C. while maintaining the rotation speed at 28 rpm, and then heated at 230 ° C. for 3 hours. The formation reaction and crushing of salt and low polymer were performed simultaneously. After releasing the water vapor generated by the reaction, the resulting reaction product was taken out.

[Step (ii)]
The reaction product obtained in the step (i) was polymerized by heating at 230 ° C. for 5 hours in a dryer under a normal pressure nitrogen stream to obtain a polyamide (P-1). About the obtained polyamide (P-1), the relative viscosity, the weight average molecular weight, the melting point, the cooling crystallization temperature, the degree of supercooling ΔT, and the amount of triamine were measured. The results are shown in Table 1.

Production Example 2
[Step (i)]
A mixture of terephthalic acid powder having a volume average particle size of 80 μm (4870 parts by mass), sodium hypophosphite (6 parts by mass) as a polymerization catalyst, and benzoic acid (72 parts by mass) as a terminal blocking agent is obtained by a ribbon blender type. The reactor was heated to 170 ° C. with stirring at a rotation speed of 30 rpm using a double helical stirring blade under nitrogen sealing. Thereafter, decanediamine (5050 parts by mass, 100% by mass) heated to 100 ° C. using a liquid injection device while maintaining the temperature at 170 ° C. and the rotation speed at 30 rpm was 28 parts by mass / min. Was added to the terephthalic acid powder continuously (continuous liquid injection method) over 3 hours to obtain a reaction product.

[Step (ii)]
The reaction product obtained in step (i) was subsequently polymerized by heating to 230 ° C. under a nitrogen stream and heating at 230 ° C. for 5 hours in the ribbon blender reactor used in step (i). Polyamide (P-2) was obtained. About the obtained polyamide (P-2), the relative viscosity, the weight average molecular weight, the melting point, the cooling crystallization temperature, the degree of supercooling ΔT, and the amount of triamine were measured. The results are shown in Table 1.

Production Examples 3 to 5 and 7
Except changing the kind of monomer to be used and the production conditions as shown in Table 1, polyamides (P-3) to (P-5) and (P-7) were obtained in the same manner as in Example 2, and each characteristic was changed. Measurements were made. The results are shown in Table 1.

Production Example 6
[Step (i)]
1,10-decanediamine (5050 parts by mass) as a diamine component, powdered terephthalic acid (4870 parts by mass) with an average particle size of 80 μm, benzoic acid (72 parts by mass) as a terminal blocking agent, and sodium hypophosphite as a polymerization catalyst Monohydrate (6 parts by mass) and 400 parts by mass of distilled water (4 parts by mass with respect to 100 parts by mass of the raw material monomers) are put in an autoclave, heated to 100 ° C., and then stirred at a rotation speed of 28 rpm. And heated for 1 hour. The mixture was heated to 230 ° C. while maintaining the rotation speed at 28 rpm, and then heated at 230 ° C. for 3 hours. The resulting solid was crushed while the salt and low polymer were formed. After releasing the water vapor, the obtained reaction product was taken out.

[Step (ii)]
The reaction product obtained in the step (i) was polymerized by heating at 230 ° C. for 5 hours under a normal pressure nitrogen stream in a dryer to obtain a polyamide (P-6). About the obtained polyamide (P-6), the relative viscosity, the weight average molecular weight, the melting point, the cooling crystallization temperature, the degree of supercooling ΔT, and the amount of triamine were measured. The results are shown in Table 1. In addition, in obtaining polyamide (P-6), since it superposed | polymerized using 4 mass parts of distilled water with respect to 100 mass parts of total amounts of a raw material monomer, manufacture other than the presence or absence of addition of distilled water is the same conditions Compared to Example 1, the weight average molecular weight was slightly lower and the amount of triamine was higher.

Production Example 8
[Step (i)]
1,10-decanediamine (5050 parts by mass) as a diamine component, powdered terephthalic acid (4870 parts by mass) with an average particle size of 80 μm, benzoic acid (72 parts by mass) as a terminal blocking agent, and sodium hypophosphite as a polymerization catalyst Monohydrate (6 parts by mass), 9200 parts by mass of distilled water (92 parts by mass with respect to 100 parts by mass of the raw material monomers) are put in an autoclave, heated to 100 ° C., and then stirred at a rotation speed of 28 rpm. And heated for 1 hour. The mixture was heated to 230 ° C. while maintaining the rotation speed at 28 rpm, and then heated at 230 ° C. for 3 hours. The resulting solid was crushed while the salt and low polymer were formed. After releasing the water vapor, the obtained reaction product was taken out.

[Step (ii)]
The reaction product obtained in the step (i) was polymerized by heating at 230 ° C. for 5 hours in a dryer under a normal pressure nitrogen stream to obtain a polyamide (P-8). About the obtained polyamide (P-8), the relative viscosity, the weight average molecular weight, the melting point, the cooling crystallization temperature, the degree of supercooling ΔT, and the amount of triamine were measured. The results are shown in Table 1. In addition, in obtaining polyamide (P-8), since it superposed | polymerized using 92 mass parts of distilled water with respect to 100 mass parts of total amounts of a raw material monomer, manufacture other than the presence or absence of addition of distilled water is the same conditions Compared to Example 1, the weight average molecular weight was significantly lower and the amount of triamine was significantly higher.

Production Example 9
[Step (i)]
1,10-decanediamine (5050 parts by mass) as a diamine component, powdered terephthalic acid (4870 parts by mass) with an average particle size of 80 μm, benzoic acid (72 parts by mass) as a terminal blocking agent, and sodium hypophosphite as a polymerization catalyst Monohydrate (6 parts by mass) and 600 parts by mass of distilled water (6 parts by mass with respect to 100 parts by mass of the raw material monomers) are put in an autoclave, heated to 100 ° C., and then stirred at a rotation speed of 28 rpm. And heated for 1 hour. The mixture was heated to 230 ° C. while maintaining the rotation speed at 28 rpm, and then heated at 230 ° C. for 3 hours. The resulting solid was crushed while the salt and low polymer were formed. After releasing the water vapor, the obtained reaction product was taken out.

[Step (ii)]
The reaction product obtained in the step (i) was polymerized by heating at 230 ° C. for 5 hours in a dryer under a normal pressure nitrogen stream to obtain a polyamide (P-9). About the obtained polyamide (P-9), the relative viscosity, the weight average molecular weight, the melting point, the cooling crystallization temperature, the degree of supercooling ΔT, and the amount of triamine were measured. The results are shown in Table 1. In addition, in order to obtain polyamide (P-9), since it superposed | polymerized using 6 mass parts of distilled water with respect to 100 mass parts of total amounts of a raw material monomer, manufacture other than the presence or absence of addition of distilled water is the same conditions Compared to Example 1, the weight average molecular weight was slightly lower and the amount of triamine was higher.

Production Examples 10 and 11
Except changing the compounding quantity of the terminal blocker to be used, polyamide (P-10) and (P-11) were obtained in the same manner as in Example 1, and each characteristic was measured. The results are shown in Table 1.

[Swelling treatment of swellable layered silicate]
1-30 g of the interlayer treating agent was dissolved or dispersed in 10 L of pure water, 100 g of swellable layered silicate was mixed, and stirred at 23 ° C. In addition, the stearylamine and 6-aminocaproic acid used the halogenated salt. Then, swelling layered silicate (A-1)-(A-9) was obtained by filtering and drying.
For (A-1) to (A-8) using stearylamine and 6-aminocaproic acid as an interlayer treatment agent, calcining in air at 600 ° C. to remove organic substances, and then measuring the mass of the residue Thus, the amount of each amine inserted between the layers was calculated. For (A-9) using a silane coupling agent, the amount of each silane coupling agent inserted between layers was calculated from the difference in mass before and after drying. The results are shown in Table 2.

Example 1
100 parts by mass of the polyamide (P-1) obtained in Production Example 1 and 5 parts by mass of the swollen layered silicate (A-1) were weighed using a Kubota loss-in-weight continuous quantitative supply device CE-W-1. The screw was supplied to the main supply port of a twin screw extruder (TEM37BS manufactured by Toshiba Machine Co., Ltd.) having a screw diameter of 37 mm and L / D = 40. The barrel temperature of the extruder was 320 ° C. to 340 ° C., the screw rotation speed was 250 rpm, and the discharge rate was 35 kg / h, and melt kneading was performed. After taking the strand from the die, it was cooled and solidified by passing through a water tank, and cut with a pelletizer to obtain polyamide resin composition pellets.

  Next, using an injection molding machine (EC100 manufactured by Toshiba Machine Co., Ltd.), the obtained polyamide resin composition pellets were injection molded under conditions of a cylinder temperature of 350 ° C. and a mold temperature of 130 ° C. to obtain test pieces. Various evaluation tests were performed using the obtained test pieces. The results are shown in Table 3.

Examples 2-3
Except having changed the compounding quantity of swelling layered silicate, after obtaining the polyamide resin composition pellet like Example 1, it injection-molded, the test piece was obtained, and various evaluation tests were done. The results are shown in Table 3.

Examples 4-12
Except having used the swelling layered silicate of Table 3, after obtaining the polyamide resin composition pellet like Example 1, it injection-molded, the test piece was obtained, and various evaluation tests were done. In Example 12, swellable fluorine mica (A-10) that was not subjected to swelling treatment was used. The results are shown in Table 3.

Examples 13-22
A polyamide resin composition pellet was obtained in the same manner as in Example 1 except that the swollen layered silicate (A-1) was added to each polyamide resin shown in Table 4, and then injection molded to give a test piece. Various evaluation tests were conducted. The results are shown in Table 4.

Comparative Examples 1-11
Without blending the swollen layered silicate, polyamide resins (P-1) to (P-11) were injection molded to obtain test pieces, and various evaluation tests were performed. The results are shown in Table 5.

Comparative Example 12
The same operation as in Example 1 was performed, and melt kneading was performed using 100 parts by mass of the polyamide resin (P-1) and 25 parts by mass of the swollen layered silicate (A-1). Since the blending amount of the salt was excessive, the polyamide resin pellets could not be obtained with the strands being cut.

Comparative Example 13
Except having changed the compounding quantity of swelling layered silicate, after obtaining the polyamide resin composition pellet like Example 1, it injection-molded, the test piece was obtained, and various evaluation tests were done. The results are shown in Table 6.

Comparative Examples 14-17
Instead of the swollen layered silicate, using any one of glass fiber, carbon fiber, and talc, and following the formulation described in Table 6, after obtaining a polyamide resin composition pellets in the same manner as in Example 1, Test pieces were obtained by injection molding, and various evaluation tests were performed. The results are shown in Table 6.

  Since Examples 1-22 obtained the polyamide resin composition using the polyamide resin prescribed | regulated to this invention and a swellable layered silicate, in addition to a mechanical characteristic (bending strength, a bending elastic modulus, load deflection temperature), a moldability A polyamide resin composition excellent in (molding cycle, continuous productivity) could be obtained. Moreover, such a polyamide resin composition is excellent in the fluidity of the molten resin at the time of melt-kneading or injection molding. In addition, among the layered silicates that have undergone swelling treatment, mechanical properties (bending strength, bending elastic modulus, deflection temperature under load) are particularly improved when swelling is performed using a compound having an amino group. It was. In Example 18, a polyamide resin composition having excellent mechanical properties was obtained. However, since the degree of supercooling ΔT exceeded 40 ° C., the molding cycle was long and the continuous productivity was poor.

  Since Comparative Examples 1-11 did not contain a swellable layered silicate, the mechanical properties (bending strength, bending elastic modulus, load deflection temperature) were inferior.

  In Comparative Example 13, since the blending of the swellable layered silicate was below the lower limit, the effect of improving the mechanical properties (bending strength, bending elastic modulus, deflection temperature under load) was poor.

  Comparative Example 15 had high specific gravity and poor fluidity because a large amount of glass fiber was blended as a filler in order to obtain mechanical properties equivalent to the polyamide resin composition obtained in the Examples.

  Since the comparative example 16 mix | blended carbon fiber as a filler in order to acquire the mechanical characteristic equivalent to the polyamide resin composition obtained in the Example, it was inferior to fluidity | liquidity.

  In Comparative Example 17, in order to obtain mechanical properties equivalent to those of the polyamide resin composition obtained in Examples, a large amount of talc was blended as a filler, so that the specific gravity was high and the fluidity was poor.

In Comparative Example 18, since talc was used instead of the swellable layered silicate, the mechanical properties were inferior and the molding cycle was long.

Claims (5)

  A polyamide resin composition comprising 100 parts by mass of a polyamide resin comprising a terephthalic acid component and a linear aliphatic diamine component having 8 to 12 carbon atoms, and 0.5 to 20 parts by mass of a swellable layered silicate.   The polyamide resin composition according to claim 1, wherein 0.5 to 30 parts by mass of a compound having an amino group is inserted between 100 parts by mass of the swellable layered silicate.   The polyamide resin composition according to claim 1 or 2, wherein the swellable layered silicate is at least one selected from swellable fluoromica, montmorillonite, and hectorite.   The method for producing a polyamide resin composition according to any one of claims 1 to 3, wherein a compound having an amino group is inserted between layers of the swellable layered silicate and then melt mixed with the polyamide resin. The molded object formed by shape | molding the polyamide resin composition in any one of Claims 1-4.