JP5371683B2 - Manufacturing method of polyamide resin composition pellets - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a meta-xylylene diamine based polyamide resin composition pellet being excellent in molding stability at molding, especially measurement stability at injection molding or extrusion molding. <P>SOLUTION: The manufacturing method for the polyamide resin composition pellet is characterized in that a polyamide resin composition containing 0-250 pts.mass of a glass fiber (B) relative to 100 pts.mass of a polyamide resin (A) containing xylylene diamine based polyamide (a) is melted and kneaded, is extruded in a strand form, is cooled and cut to obtain the polyamide resin composition pellet, and subsequently, crystallinity of the polyamide resin composition pellet is made higher by 5% than the crystallinity before crystallization treatment by applying the crystallization treatment to the pellet. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a polyamide resin composition pellet, and more particularly relates to a method for producing a polyamide resin composition pellet having excellent molding stability at the time of molding, and particularly excellent metering stability at the time of injection molding or extrusion molding.

  Polyamide resin is an engineering plastics with excellent mechanical strength such as impact resistance, friction resistance and wear resistance, heat resistance, and oil resistance. It is an automotive part, electronic / electric equipment part, OA equipment part, machine. It is widely used in fields such as parts, building materials and housing equipment, and the field of use has expanded in recent years.

  There are many known polyamide resins such as polyamide 6 and polyamide 66, but xylylenediamine-based polyamides obtained from xylylenediamine and α, ω-linear aliphatic dibasic acids such as adipic acid. Unlike polyamide 6 and polyamide 66, it has an aromatic ring in the main chain, has high mechanical strength and elastic modulus, low water absorption, and excellent oil resistance. It is suitable for precision molding because of its small ratio and small shrinkage and warping, and is positioned as an extremely excellent polyamide resin. In addition, xylylenediamine-based polyamide reinforced with glass fiber, inorganic filler, etc. can achieve the highest strength and rigidity among engineering plastics and can be applied to structural parts as a metal substitute material. is there. For these reasons, xylylenediamine-based polyamides are used as molding materials in various fields such as transport parts such as automobiles, general machine parts, precision machine parts, electronic / electric equipment parts, leisure sports equipment, and civil engineering and building materials. In recent years, it has been used more and more widely.

  By the way, to obtain a molded product by molding a polyamide resin containing xylylenediamine-based polyamide, pellets obtained by compounding polyamide with various additives and reinforcing materials are usually produced by injection molding or extrusion molding. There are many cases. For example, in injection molding, a screw is rotatably and reciprocally disposed in a heating cylinder of an injection molding machine, and 1) in front of a resin pellet introduced from a hopper by rotating and reciprocating operation of the screw. 2) Plasticizing and melting by means of screw kneading and compression (compression process), 3) Metering for one shot (metering process), and finally 4) Injection from an injection nozzle (injection process) ) Is performed.

  However, when xylylenediamine-based polyamide is used as a raw material pellet and such molding is performed, the molding stability of xylylenediamine-based polyamide is not sufficient and the molding becomes unstable compared to ordinary polyamide resins. The situation is likely to happen. That is, when xylylenediamine polyamide pellets are introduced from a hopper, and the pellet melt reaches the metering step through the supply step and the compression step, the situation where the metering becomes unstable is likely to occur. This measuring step is a step of storing the melted resin material for one shot in the head portion in front of the screw and having the screw head, the backflow prevention ring and the sealing. It is performed by a method such as monitoring at a predetermined amount of time (measuring time). In the case of xylylenediamine-based polyamide, the measurement time is likely to vary. For example, even if the initial setting time is set to 5 seconds, the measurement time jumps to nearly 2 to 3 times as the shot is repeated. It became clear that measurement instability such as

  Such metering instability is usually thought to be due to insufficient melting in the compression process, but metering instability is not to all of the polyamide resin pellets, but to xylylenediamine-based Since it frequently occurs in the case of polyamide pellets, it is considered to be caused by some circumstances peculiar to xylylenediamine polyamide pellets.

  Conventionally, various proposals have been made to improve the moldability of xylylenediamine-based polyamides or xylylenediamine-based polyamide resin compositions containing glass fibers. For example, there is a method of blending polyamide 66 to shorten the molding cycle time (see Patent Document 1). However, only by blending polyamide 66, this measurement instability is not improved.

  In addition, regarding the production of xylylenediamine-based polyamide pellets, when the molten strand is cooled and solidified, the particle size and amount of the powder in the refrigerant is set to a specified value or less to reduce the foreign matter content of the molded product (Patent Literature). 2), shaped pellets, crushed pieces, powders, etc. in the pellet granulation process, with the parameter values defined in relation to the temperature of the refrigerant, the melted strand, and the semicrystallization time of the xylylenediamine polyamide as a specific range Although a method for suppressing the generation of industrial waste (see Patent Document 3) has been proposed, proposals have been made that lead to stabilization of meterability during molding of xylylenediamine-based polyamide pellets. Absent.

  Under such circumstances, there has been a strong demand for the development of a method for producing MX polyamide resin composition pellets that are excellent in molding stability at the time of molding, particularly metering stability at the time of injection molding or extrusion molding.

Japanese Patent Publication No.54-32458 Japanese Patent Laid-Open No. 2005-2298 JP 2003-327692 A

  An object of the present invention is to provide a method for producing a xylylenediamine-based polyamide resin composition pellet having excellent molding stability during molding, in particular, excellent metering stability during injection molding or extrusion molding. It is to provide.

  As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors have sent xylylenediamine-based polyamide to a molding machine because the crystallization speed is slower than that of other polyamides, and the crystallization is insufficient. In the molding machine, crystallization proceeds and the pellets shrink, and the shrunken pellets stick to the screw in the cylinder, creating a space between the cylinder and the pellet. And due to the effect of this space, the heat of the cylinder is not sufficiently transferred to the pellets, and the pellets are not sufficiently melted and unstable, and as a result, the weighing is difficult to perform well, and the weighing may not be stable. I came to guess. Therefore, if the crystallization of the pellets is sufficiently performed and the degree of crystallization of the pellets is increased in advance, the shrinkage of the pellets is small, and the pellets are sufficiently uniformly melted in the supply process and the compression process, and the weighing is stabilized. The present invention has been completed.

That is, according to the first invention of the present invention, a polyamide resin (A) containing a xylylenediamine-based polyamide (a) obtained by a polycondensation reaction between xylylenediamine and an α, ω-linear aliphatic dibasic acid. ) 100 parts by mass of the polyamide resin composition containing 0 to 250 parts by mass of the glass fiber (B), extruded into a strand, cooled and cut to obtain a polyamide resin composition pellet, By holding the pellet in an air atmosphere at a temperature of 100 to 160 ° C. for 15 minutes or longer , sufficient crystallization treatment is performed so that the degree of crystallization after the crystallization treatment is 5% or more higher than that before the crystallization treatment. and facilities, manufacturing method of injection molding a polyamide resin composition pellets, wherein the crystallinity after crystallization is 23 to 35% is provided.

According to the second invention of the present invention, in the first invention, the polyamide resin (A) contains a polyamide (b) other than the xylylenediamine-based polyamide (a), and the content thereof is Provided is a method for producing polyamide resin composition pellets for injection molding, which is 0.1 to 30% by mass with respect to 100% by mass of the polyamide resin (A).

Further, according to the third aspect of the present invention, in the second invention, xylylenediamine-based polyamide (a) except polyamide (b) is, for injection molding, which is a polyamide 66 or polyamide 6 A method for producing a polyamide resin composition pellet is provided.

According to the fourth invention of the present invention, in any one of the first to third inventions, the content of the glass fiber (B) is a polyamide resin (A) 100 containing a xylylenediamine polyamide (a). The manufacturing method of the polyamide resin composition pellet for injection molding characterized by being 40-150 mass parts with respect to a mass part is provided.

  According to the method for producing a polyamide resin composition pellet of the present invention, it is possible to obtain a xylylenediamine-based polyamide resin composition pellet excellent in molding stability at the time of molding, particularly measurement stability at the time of injection molding or extrusion molding. it can.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the embodiments and examples described below, and may be arbitrarily selected without departing from the scope of the present invention. You can change it to

[1. Overview]
The method for producing the polyamide resin composition pellets of the present invention comprises melt-kneading, extruding, and cooling a polyamide resin composition in which a glass fiber is preferably blended with a polyamide resin (A) containing xylylenediamine polyamide (a). The polyamide resin composition pellets obtained by cutting are subjected to sufficient crystallization treatment so that the degree of crystallization after crystallization treatment is 5% higher than that before crystallization treatment.

[2. Polyamide resin (A)]
The polyamide resin (A) used in the polyamide resin composition of the present invention is a polyamide containing a xylylenediamine-based polyamide (a) obtained by a polycondensation reaction between xylylenediamine and an α, ω-linear aliphatic dibasic acid. Resin.

The xylylenediamine polyamide (a) is obtained by a polycondensation reaction between xylylenediamine and an α, ω-linear aliphatic dibasic acid.
As xylylenediamine, metaxylylenediamine or paraxylylenediamine may be used singly or as a mixture thereof, and in the range of metaxylylenediamine 50-100 mol% and paraxylylenediamine 50-0 mol%. It is preferable to use it. If the amount of paraxylylenediamine exceeds 50 mol%, the melting point of the xylylenediamine-based polyamide obtained becomes too high, and heat deterioration due to heating at the time of molding tends to occur, and molding becomes difficult.

  When using a mixture of metaxylylenediamine and paraxylylenediamine, preferably 15 to 45 mol% of paraxylylenediamine and 85 to 55 mol% of metaxylylenediamine, most preferably paraxylenediamine. It is a mixed diamine composed of 20 to 40 mol% xylylenediamine and 80 to 60 mol% metaxylylenediamine. If the amount of paraxylylenediamine is less than 15 mol%, it is difficult to improve the melting point sufficiently, and if it exceeds 45 mol%, the melting point becomes too high, and there is a risk of inconvenience such as thermal deterioration during polymerization and molding. Therefore, it is not preferable. As the diamine in the mixed diamine, in addition to paraxylylenediamine and metaxylylenediamine, other diamines such as aliphatic diamine, aromatic diamine and alicyclic diamine may be mixed and used. The use ratio is preferably 10 mol% or less of the total diamine, and more preferably 5 mol% or less of the total diamine. Examples of the aliphatic diamine include tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, octamethylene diamine, and nonamethylene diamine. Examples of the aromatic diamine include metaphenylene diamine and paraphenylene diamine. Examples of the alicyclic diamine include 1,3-bisaminomethylcyclohexane and 1,4-bisaminomethylcyclohexane.

  The α, ω-linear aliphatic dibasic acid that is the other condensation raw material is preferably an aliphatic dicarboxylic acid having 6 to 12 carbon atoms. Specific examples include adipic acid, succinic acid, glutaric acid, Examples include pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and among them, adipic acid is particularly preferable. In addition to the aliphatic dicarboxylic acid, a small amount of aromatic dicarboxylic acid can also be used. Examples of the aromatic dicarboxylic acid include 1,5-naphthalenedicarboxylic acid and the like, and use when the aromatic dicarboxylic acid is used. The amount is preferably 10 mol% or less, more preferably 5 mol% or less of the total dicarboxylic acid.

  The relative viscosity of the xylylenediamine-based polyamide (a) (measurement conditions in 96% sulfuric acid, concentration 1 g / 100 ml, temperature 25 ° C.) is preferably 1.6 to 3.0, more preferably 1 0.7 to 2.9, and most preferably 1.8 to 2.8. If the relative viscosity is too low, the mechanical strength is insufficient, and if it is too high, the moldability tends to decrease.

  The polyamide resin (A) in the present invention may contain other polyamides in addition to the xylylenediamine polyamide (a). Other polyamides (b) other than the xylylenediamine polyamide (a) include polyamide 66, polyamide 6, polyamide 46, polyamide 6/66, polyamide 10, polyamide 612, polyamide 11, polyamide 12, metaxylylenediamine, Polyamide MP / 6T composed of paraxylylenediamine, adipic acid and terephthalic acid, polyamide 66 / 6T composed of hexamethylenediamine, adipic acid and terephthalic acid, polyamide 6I / 6T composed of hexamethylenediamine, isophthalic acid and terephthalic acid Can be mentioned. Among these, it is preferable to contain polyamide 66 and polyamide 6, particularly polyamide 66 that has a high crystallization rate, good fluidity, and good thermal stability.

  The relative viscosity of these polyamides (b) (measurement conditions in 96% sulfuric acid, concentration 1 g / 100 ml, temperature 25 ° C.) is preferably 1.8 to 3.5, more preferably 2.0 to 3 .2, most preferably 2.1-3.0. If the relative viscosity is too low, the mechanical strength is insufficient, and if it is too high, the moldability tends to decrease.

  The content of the polyamide (b) other than the xylylenediamine polyamide (a) is the total of the polyamide (b) other than the xylylenediamine polyamide (a) and the xylylenediamine polyamide (a). Polyamide (b) is 0.1 to 30% by mass, preferably polyamide (b) is 1 to 20% by mass, and particularly 3 to 15% by mass with respect to 100% by mass. If the polyamide (b) other than the xylylenediamine polyamide (a) exceeds 30% by mass, the elastic modulus tends to decrease.

  Further, other thermoplastic resins may be added to form a polymer alloy. For example, from the viewpoint of improving the chemical resistance and slidability of polyamide resin, modified polypropylene resin, polyphenylene sulfide resin, from the viewpoint of improving impact resistance, polyphenylene. You may mix | blend ether resin, ABS resin, etc.

  The pellet of the present invention preferably contains glass fiber (B) in order to impart warpage performance, mechanical strength and rigidity to the molded product. The content is 0 to 250 parts by mass, preferably 20 to 200 parts by mass, particularly 40 to 150 parts by mass with respect to 100 parts by mass of the polyamide resin (A). If the glass fiber (B) is less than 20 parts by mass, it may not be sufficient to exhibit strength and rigidity as mechanical parts, and if it exceeds 250 parts by mass, the melt viscosity of the polyamide resin composition becomes very high. Therefore, it is difficult to manufacture a molded product by injection molding or the like.

The composition of the glass fiber is arbitrary, but a composition capable of forming glass fiber is better than molten glass. Preferable compositions include E glass composition, C glass composition, S glass composition, alkali-resistant glass and the like. Usually, E glass is preferable because it is easily available. Although the tensile strength of glass fiber is arbitrary, 290 kg / mm < ² > or more is preferable.

  The glass fiber is preferably surface-treated with a silane coupling agent such as γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. The adhesion amount of the surface treatment agent is usually preferably 0.01% by mass or more of the glass fiber mass.

  Further, if necessary, lubricants such as fatty acid amide compounds, silicone oils, antistatic agents such as quaternary ammonium salt compounds, resin mixtures having film forming ability such as epoxy resins, acrylic resins, urethane resins, film forming ability Glass fiber surface-treated with a combination of a resin having a heat stabilizer, a flame retardant, or the like may be used.

  Moreover, the polyamide resin composition in the present invention can contain other fillers other than glass fibers, and preferably contains talc. There is no restriction | limiting in particular in the kind of talc, what is known conventionally is used, The content becomes like this. Preferably it is 0.1-10 mass parts with respect to 100 mass parts of polyamide resins (A), Especially Is 0.5-8 parts by mass.

  The polyamide resin composition may further contain other fillers, such as carbon fiber, inorganic fibers such as ceramic fibers, metal fibers such as stainless steel fibers, organic fibers such as liquid crystalline wholly aromatic polyamides, Examples include mica, potassium titanate, aluminum borate, titanium oxide, calcium carbonate, and wollastonite.

  Furthermore, the polyamide resin composition may contain other components other than those described above, for example, resin additives and the like, if necessary. For example, heat stabilizer, antioxidant, release agent, ultraviolet absorber, dye / pigment, flame retardant, anti-dripping agent, antistatic agent, antifogging agent, lubricant, antiblocking agent, fluidity improver, plasticizer, A dispersing agent, an antibacterial agent, etc. are mentioned.

[Production of polyamide resin composition pellets]
In order to produce pellets of such a polyamide resin composition, first, using an extruder, xylylenediamine-based polyamide (a) is added to the hopper of the extruder, if necessary, other polyamide (b), Glass fiber (B) or the like is charged, or glass fiber (B) is side-fed, or a premix obtained by mixing them in advance is charged into a hopper and melt-kneaded.
The extruder is a type in which the resin composition raw material is heated and continuously extruded from a die using a screw, and a single-screw extruder, a vented extruder, a multi-screw extruder, etc. are usually used. Although used, it is also possible to use an extruder without a screw.

  With such an extruder, the polyamide resin composition is melt-kneaded and extruded as a strand from a die nozzle. The cross section of the strand is preferably a shape close to a circle such as a circle or an ellipse, and the diameter is usually 1 to 5 mm, preferably 1.5 to 4.5 mm, and more preferably 2 to 4 mm.

  The strand extruded from the die nozzle is in a high-temperature melted state at 240 to 400 ° C., and cannot be cut with a pelletizer as it is, so it needs to be cooled and solidified to 230 ° C. or lower and the normal temperature below the melting point. Usually, water is used for this cooling, and the strand extruded from the die nozzle is cooled with water. In order to cool by water, a method of allowing a strand to pass through a water tank containing water is generally used. However, a method of cooling by showering the strand while conveying the strand on a conveyor belt is also preferable. As temperature of the water used for cooling, it is 20-80 degreeC normally, Preferably it is 30-60 degreeC.

  The cooled strand becomes a pellet by being cut by a pelletizer. As a shape of a pellet, it is cylindrical shape normally, The length is 1-25 mm normally, Preferably it is 2-15, More preferably, it is 2-8 mm.

  The obtained polyamide resin composition pellets are subjected to crystallization treatment. In the crystallization treatment, sufficient crystallization treatment is performed so that the degree of crystallization of the polyamide resin composition pellets is 5% or more higher than the degree of crystallization before the crystallization treatment. As a preferable method for such crystallization, holding in an air atmosphere at a temperature of 100 to 160 ° C. for 15 minutes or more can be mentioned. If the temperature is lower than 100 ° C., crystallization does not proceed so much, and if the temperature exceeds 160 ° C. for a long time, the pellet may be discolored. More preferable crystallization conditions vary depending on the glass fiber content, but are about 15 to 60 minutes at a temperature of 110 to 150 ° C. Moreover, from the point of measurement stability at the time of shaping | molding by a crystallization process, content of glass fiber (B) is 150 mass parts with respect to 100 mass parts of polyamide resins (A) containing a xylylenediamine polyamide (a). It is preferable that it is below, and 120 weight part or less is more preferable. Since the resin composition having such a glass fiber content has a high proportion of amorphous parts in the resin composition after melt-kneading at the time of pellet production, the measurement stability effect at the time of molding by crystallization treatment is remarkable. Tend to be.

Here, the crystallinity before and after the crystallization treatment is measured as follows.
That is, in the method for producing resin composition pellets of the present invention, the crystallinity D ₁ (%) of the resin composition pellets that are not subjected to crystallization treatment can be measured based on the following method.

  The resin composition pellets obtained after melt-kneading are allowed to stand at room temperature for 12 hours and then a 10 mg sample is cut out and heated at a rate of 10 ° C./min from 30 ° C. to 300 ° C. using a differential scanning calorimetry (DSC) method. Then, the calorific value of the exothermic peak and the endothermic peak at the time of temperature rise is obtained, and the crystallinity is calculated by the following equation.

Crystallinity D ₁ (%) = [heat quantity of endothermic peak (J / g) −heat quantity of exothermic peak (J / g)] / [theoretical heat of fusion of polyamide resin (J / g)] × 100
The crystallinity D ₁ (%) in the above formula when the polyamide (b) other than the xylylenediamine polyamide (a) is contained is the total crystallinity of both resins (a) and (b). Say. In this case, an endothermic / exothermic peak derived from xylylenediamine-based polyamide (a) and an endothermic / exothermic peak derived from polyamide (b) other than xylylenediamine-based polyamide (a) are observed (endothermic peaks of both resins, Exothermic peaks may overlap each other), but the endothermic peak in the above formula is the sum of the endothermic peaks derived from the respective resins, and the exothermic peak in the above formula is the sum of the exothermic peaks derived from the respective resins. .
In addition, when the polyamide (b) other than the xylylenediamine polyamide (a) is contained, the theoretical heat of fusion in the above formula is the total heat obtained by multiplying the theoretical heat of heat of each resin by the ratio. . For example, a mixed polyamide containing 90% by mass of a xylylenediamine polyamide (a) having a theoretical heat of fusion Qa and 10% by mass of a polyamide (b) other than the xylylenediamine polyamide (a) having a theoretical heat of heat Qb In the case of resin, the theoretical heat of fusion of the polyamide resin is calculated as “Qa × 0.9 + Qb × 0.1”.

Here, the method of measuring the theoretical heat of fusion of each resin in the present invention will be described using an example of xylylenediamine-based polyamide.
The endothermic peak calories at the melting point of xylylenediamine-based polyamides with various crystallinities were measured by DSC, and the endothermic peak calories and crystallinity obtained were plotted on two axes to create a calibration curve. The amount of heat at an extrapolation point of 100% crystallinity of the line is defined as the theoretical heat of fusion. The crystallinity of the xylylenediamine-based polyamide used for the DSC measurement can be measured in accordance with the JIS K7112 standard using a generally used density gradient tube method.
In the case of polyamide (b) other than xylylenediamine polyamide (a), the theoretical heat of fusion can be determined by the same method as described above.

The crystallinity D ₂ in the resin composition pellets subjected to the crystallization treatment was also measured by measuring 10% of the sample after leaving the resin composition pellets after the crystallization treatment at room temperature for 12 hours, and measuring the crystallinity D ₁ . It can be obtained by the same method.

  In the present invention, the obtained polyamide resin composition pellets are subjected to a crystallization treatment so that the crystallization degree after the treatment is higher by 5% or more than the crystallization degree before the crystallization treatment. The degree of crystallinity before the crystallization treatment is usually about 10 to 20%, but it is preferable to improve this to about 23 to 35% by the crystallization treatment. Thus, by increasing the degree of crystallinity of the pellets by 5% or more, the obtained pellets are sufficiently uniformly melted in the feeding step in the molding machine during actual molded product production, Weighing is performed stably.

The method for obtaining a molded product from the polyamide resin composition pellets obtained in the present invention is not particularly limited, and a molding method generally employed for the polyamide resin composition can be arbitrarily adopted. For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, hollow molding method such as gas assist, molding method using heat insulation mold, rapid heating mold Molding methods, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding method, extrusion molding method, sheet molding method, thermoforming method, rotational molding method, laminate molding method, etc. .
A molded product obtained by molding using the pellets of the present invention is free from defects such as poor appearance due to insufficient measurement.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
The measurement / evaluation methods and materials used in the examples and comparative examples are as follows. The relative viscosity of the polyamide resin was measured in a 96% sulfuric acid solution at a concentration of 1 g / 100 ml and a temperature of 25 ° C.

1. Materials used (A) Polyamide resin (a) Component [Xylylenediamine-based polyamide]
(A-1) Production of meta / para-mixed xylylenediamine polyamide “MP6” 730 g of adipic acid was charged into a 3 liter flask equipped with a stirrer, thermometer, reflux condenser, raw material dripping device, and heating device. In a nitrogen atmosphere, the temperature inside the flask was raised to 160 ° C. to melt adipic acid. Next, 680 g of mixed xylylenediamine containing 30 mol% of paraxylylenediamine and 70 mol% of metaxylylenediamine was successively added dropwise into the flask over 2.5 hours.
During this time, the temperature in the flask was constantly maintained above the melting point of the product while stirring, and the reaction was continued. At the end of the reaction, the temperature was raised to 270 ° C. Water generated by the reaction was discharged out of the reaction system by a partial condenser. After completion of the dropwise addition, the reaction was continued by stirring at a temperature of 275 ° C., and the reaction was terminated after 1 hour. The product was removed from the flask, cooled with water and pelletized. The obtained meta / para mixed xylylenediamine polyamide had a melting point of 258 ° C., a crystallization temperature of 216 ° C., and a relative viscosity of 2.08.

(A-2) Metaxylylenediamine adipamide “MXD6”
Product name “Polyamide MXD6 # 6000” manufactured by Mitsubishi Gas Chemical Company, Inc.
Melting point 243 ° C., relative viscosity 2.14
Component (b) [Polyamide other than xylylenediamine-based polyamide]
(B-1) Polyamide 66 “PA66”
Product name “Zytel (registered trademark) 101” manufactured by DuPont Relative viscosity 3.0
(B-2) Polyamide 6 “PA6”
Product name “Novamid (registered trademark) 1013J” manufactured by Mitsubishi Engineering Plastics Co., Ltd., relative viscosity 2.5

(B) Glass fiber (B-1) "GFA"
Nippon Electric Glass chopped strand "ECS03T-275H"
(B-2) “GFB”
Owens Corning Manufacturing Chopped Strand "CS03JAFT2"
(C) Talc Hayashi Kasei Co., Ltd., trade name "Micron White # 5000S"
(D) Release agent Montanate ester wax Product name “Licowax (registered trademark) Licowax E” manufactured by Clariant Japan

(Examples 1-4, Comparative Examples 1-5)
<Method for producing resin composition>
Examples 1-4 and Comparative Examples 1-5
The above components (A) to (D) are blended in the proportions (parts by mass) shown in Table 1, components other than glass fiber (B) are blended with a tumbler, and a twin screw extruder (Toshiba Machine Co., Ltd. “TEM35B After the glass fiber (B) was contained, the resin pellets were prepared by side-feeding. The temperature setting of the extruder was 280 ° C. up to the side feed part and 260 ° C. from the side feed part. The obtained pellets were put in a tank and kept at the temperature and time shown in Table 1 to perform crystallization treatment. In Comparative Example 5, no crystallization treatment was performed.

<Evaluation method>
[Crystallinity]
A 10 mg sample was cut out from the resin composition pellets obtained by the above method, and the obtained sample was subjected to a rate of 10 ° C./min from 30 to 300 ° C. using a DSC-6200 manufactured by Seiko Instruments. in heated, according to the measurement method described above, it was measured crystallization temperature D ₂ after treatment with the crystallization temperature D ₁ of the pre-crystallization process.

[Formability]
Using the crystallized resin composition pellets obtained by the above method (Comparative Example 5 has no crystallization treatment), using a FANUC injection molding machine 100T, cylinder temperature setting 280 ° C. (uniform), 20 shots of a test piece of length 100 × width 100 × 2 mm thickness were formed under the conditions of a measurement value of 55 mm, an initial measurement time of 5 seconds, a rotation speed of 100 rpm, and a back pressure of 2 MPa, and each shot was measured under the above conditions. The average value of the weighing time was obtained from the time. In addition, the meterability during molding was evaluated according to the following criteria. The fact that the metering time is stable indicates that it is preferable because the pellets are well bite into the molding machine screw and the molding cycle is also stable.
○ (Measurement stability): The maximum and minimum values of the measurement time are less than ± 0.5 sec of the average value of the measurement time.
Δ (Weighing unstable): The maximum value and / or the minimum value of the weighing time is ± 2.0 sec or more of the average value of the weighing time. X (Cannot be measured): The pellet is not sufficiently melted and unstable. Table 1 shows the above evaluation results.

  As can be seen from Examples 1 to 4, it can be seen that the meterability is extremely stable by performing sufficient crystallization treatment so that the degree of crystallization after crystallization treatment is increased by 5% or more. On the other hand, in Comparative Examples 1 to 5 in which the crystallization after the crystallization treatment is insufficient and the increase in the degree of crystallinity is less than 5%, the meterability is very poor, and the average value of the measurement time is 5 seconds as the initial setting time. On the other hand, it can be seen that it has jumped about twice. In addition, the variation in the measurement time of each shot is large.

  Therefore, from the above-mentioned examples and comparative examples, the effect that the molding stability at the time of molding, in particular, the metering stability at the time of injection molding or extrusion molding is excellent can be obtained for the first time by the configuration of the present invention. It was confirmed to be a thing.

  According to the method for producing a polyamide resin composition pellet of the present invention, a xylylenediamine-based polyamide resin composition pellet excellent in molding stability during molding, in particular, metering stability during injection molding or extrusion molding can be obtained. It can be used to form molded products in a wide range of fields such as automobile parts, general machine parts, precision machine parts, electronic / electric equipment parts, leisure sports equipment, civil engineering and building materials, etc. Usability is very high.

Claims (4)

Glass fiber (B) 0 with respect to 100 parts by mass of polyamide resin (A) containing xylylenediamine-based polyamide (a) obtained by polycondensation reaction of xylylenediamine and α, ω-linear aliphatic dibasic acid A polyamide resin composition containing ˜250 parts by mass is melt-kneaded, extruded into a strand, cooled and cut to obtain a polyamide resin composition pellet, and then the pellet is heated to a temperature of 100 to 160 ° C. in an air atmosphere. Te, by holding more than 15 minutes, the degree of crystallinity after crystallization is facilities sufficient crystallization process is higher than 5% than that before the crystallization treatment, the degree of crystallinity after crystallization is 23 A process for producing a polyamide resin composition pellet for injection molding , characterized in that it is -35% . The polyamide resin (A) contains a polyamide (b) other than the xylylenediamine-based polyamide (a), and the content thereof is 0.1 to 30% by mass with respect to 100% by mass of the total polyamide resin (A). The method for producing a polyamide resin composition pellet for injection molding according to claim 1. The method for producing a polyamide resin composition pellet for injection molding according to claim 2 , wherein the polyamide (b) other than the xylylenediamine-based polyamide (a) is polyamide 66 or polyamide 6. Content of the glass fibers (B) is, with respect to the polyamide resin (A) 100 parts by mass of containing xylylenediamine-based polyamide (a), any of the claims 1-3, characterized in that 40 to 150 parts by weight A process for producing a polyamide resin composition pellet for injection molding according to claim 1.