JP5621449B2 - Manufacturing method of polyamide resin composition pellets - Google Patents

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 polyamide obtained from xylylenediamine and an α, ω-linear aliphatic dibasic acid such as adipic acid. Unlike polyamide 6 and polyamide 66, the resin has an aromatic ring in the main chain, high mechanical strength and elastic modulus, low water absorption, excellent oil resistance, and in molding, It is suitable for precision molding due to its small shrinkage and small shrinkage and warping, and is positioned as an extremely excellent polyamide resin. In addition, xylylenediamine-based polyamide resin 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. It is. For these reasons, xylylenediamine-based polyamide resins are molding materials in various fields such as transportation equipment parts such as automobiles, general machine parts, precision machine parts, electronic / electric equipment parts, leisure sports equipment, civil engineering and building materials. In recent years, it has been used more and more widely.

  By the way, in order to obtain a molded product by molding a polyamide resin containing a xylylenediamine-based polyamide resin, pellets obtained by compounding various additives and reinforcing materials in accordance with the desired specifications are usually used. Are often produced by injection molding or extrusion. For example, in injection molding, a screw is rotatably and reciprocally disposed in a heating cylinder of an injection molding machine, and 1) to the front of a resin pellet introduced from a hopper by rotating and reciprocating the screw. 2) Plastic feed and melt (compression process) by kneading and compression with a screw (compression process), 3) Weighing for one shot (metering process), and finally 4) Injection from an injection nozzle (injection process) A series of operations are performed.

  However, when xylylenediamine-based polyamide resin is used as a raw material pellet and such molding is performed, the xylylenediamine-based polyamide resin is not sufficiently stable in molding as compared with ordinary polyamide resin, and molding is difficult. A stable situation is likely to occur. That is, when xylylenediamine polyamide resin pellets are introduced from a hopper and the pellet melt reaches the metering process through the supply process and the compression process, a situation in which metering tends to become 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 resin, the measurement time is likely to vary. For example, even if the initial setting time is set to 5 seconds, the measurement time is nearly 2-3 times as long as the shot is repeated. It became clear that measurement instability such as jumping up was likely to occur.

  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 resin pellets, it is considered to be caused by some circumstances peculiar to xylylenediamine-based polyamide resin pellets.

  Conventionally, various proposals have been made to improve the moldability of xylylenediamine-based polyamide resins 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 polyamide resin pellets, when the molten strand is cooled and solidified, the particle size and amount of the powder in the refrigerant are set below the specified value to reduce the foreign matter content of the molded product (patent Reference 2), the temperature of the refrigerant, the melted strand, and the parameter values defined in relation to the semicrystallization time of the xylylenediamine-based polyamide resin within a specific range, the shaped pellets, crushed pieces and powder in the pellet granulation process Although a method (see Patent Document 3) that attempts to suppress the generation of industrial waste such as body has been proposed, a proposal that leads to stabilization of meterability when molding xylylenediamine-based polyamide resin pellets Has not been made.

Further, in recent years, a polyamide resin from xylylenediamine and sebacic acid (hereinafter also referred to as “xylylene sebacamide polyamide resin”) has been conventionally used as a xylylenediamine polyamide resin as a xylylenediamine polyamide resin. Compared with a polymethoxyxylene adipamide resin (hereinafter, also referred to as “MXD6”), which is widely used, it is highly expected as a material for various parts because it is excellent in chemical resistance and impact resistance. However, the above-described problems are more remarkable in the xylylene sebacamide-based polyamide resin.
Under such circumstances, development of a method for producing a xylylene sebacamide-based polyamide resin composition pellet having excellent molding stability during molding, particularly measurement stability during injection molding or extrusion molding, has been strongly desired.

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

  The object of the present invention is to produce a xylylene sebacamide-based polyamide resin composition pellet excellent in molding stability at the time of molding, in particular, measurement stability at the time of injection molding or extrusion molding, in view of the above-mentioned problems of the prior art. It is to provide a method.

  As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors have found that xylylene sebacamide-based polyamide resin has a slower crystallization rate than other polyamide resins and MXD6, so that crystallization is not possible. If insufficient pellets are fed into the molding machine, crystallization proceeds in the molding machine and the pellets shrink, resulting in the shrinking pellets hugging the screws in the cylinder, creating a space between the cylinder and the pellets. . 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, the organic nucleating agent (B) is added in an amount of 0.1 to 50 per 100 parts by mass of the polyamide resin (A) obtained by the polycondensation reaction of xylylenediamine and sebacic acid. Polyamide resin composition pellets obtained by melt-kneading a polyamide resin composition containing parts by mass, extruding into a strand shape, cooling and cutting, the crystallinity after crystallization treatment being crystallized. A polyamide resin characterized by being subjected to a sufficient crystallization treatment to be higher by 5% or more than before the crystallization treatment, and the melting point of the organic nucleating agent (B) is higher than the melting point of the polyamide resin (A) by 50 ° C. A method for producing a composition pellet is provided.

  According to the second invention of the present invention, in the first invention, the temperature difference between the crystallization temperature of the polyamide resin (A) and the crystallization temperature of the organic nucleating agent (B) is 50 ° C. or less. A method for producing a characteristic polyamide resin composition pellet is provided.

  According to the third invention of the present invention, in the first or second invention, the crystallization treatment is performed by holding the pellet in an air atmosphere at a temperature of 100 to 160 ° C. for 15 minutes or more. A process for producing a polyamide resin composition pellet is provided.

  According to the fourth aspect of the present invention, in any one of the first to third aspects, the difference between the melting point of the polyamide resin (A) and the melting point of the organic nucleating agent (B) is 60 ° C. or higher. A method for producing a characteristic polyamide resin composition pellet is provided.

  According to the fifth aspect of the present invention, in any one of the first to fourth aspects, the temperature difference between the crystallization temperature of the polyamide resin (A) and the crystallization temperature of the organic nucleating agent (B) is 40 ° C. There is provided a method for producing a polyamide resin composition pellet characterized by the following.

  According to a sixth aspect of the present invention, there is provided a method for producing a polyamide resin composition pellet according to any one of the first to fifth aspects, wherein the organic nucleating agent (B) is polyamide 66. Provided.

  Furthermore, according to the seventh invention of the present invention, in any one of the first to sixth inventions, the glass fiber (C) is further contained in an amount of 10 to 250 parts by mass with respect to 100 parts by mass of the polyamide resin (A). A method for producing a polyamide resin composition pellet is provided.

  According to the method for producing a polyamide resin composition pellet of the present invention, a xylylene sebacamide-based polyamide resin composition pellet excellent in molding stability during molding, in particular, metering stability during injection molding or extrusion molding, is obtained. be able to.

  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 comprising a xylylene sebacamide-based polyamide resin (A) and an organic nucleating agent (B). A polyamide resin composition pellet obtained by cutting, and subjecting the pellet to a sufficient crystallization treatment so that the degree of crystallization after the crystallization treatment is 5% or more higher than that before the crystallization treatment. And the melting point of the organic nucleating agent (B) is higher than the melting point of the polyamide resin (A) by more than 50 ° C.

[2. Polyamide resin (A)]
The polyamide resin (A) used in the polyamide resin composition of the present invention is a polyamide resin obtained by a polycondensation reaction between xylylenediamine and sebacic acid.
As xylylenediamine, metaxylylenediamine or paraxylylenediamine may be used alone or as a mixture thereof, and in the range of 40 to 100 mol% of metaxylylenediamine and 60 to 0 mol% of paraxylylenediamine. It is preferable to use it. When the amount of paraxylylenediamine exceeds 60 mol%, the melting point of the xylylene sebacamide-based polyamide resin obtained becomes too high, and heat deterioration due to heating during molding tends to occur, and the crystallization speed becomes too fast. It may get worse.

  When mixing and using metaxylylenediamine and paraxylylenediamine, the mixing ratio is preferably 15 to 60 mol% for paraxylylenediamine, 85 to 40 mol% for metaxylylenediamine, and more preferably Is 15 to 45 mol% paraxylylenediamine and 85 to 55 mol% metaxylylenediamine, most preferably 20 to 40 mol% paraxylylenediamine and 80 to 60 mol% metaxylylenediamine A mixed diamine consisting of If the amount of paraxylylenediamine is less than 15 mol%, the crystallization rate may decrease and the molding cycle may be prolonged, and sufficient melting point may not be improved, resulting in insufficient heat resistance. If it exceeds 50%, the melting point becomes too high, and there is a possibility of causing inconveniences such as thermal degradation during polymerization and molding, such being undesirable. 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.

As sebacic acid, which is the other condensation raw material, sebacic acid may be used alone, or other dicarboxylic acids may be mixed and used.
The dicarboxylic acid used as a mixture is preferably an aliphatic dicarboxylic acid having 6 to 12 carbon atoms, more preferably 6 to 9 carbon atoms. Specific examples include adipic acid, succinic acid, glutaric acid, pimelic acid, and suberin. Examples include acid, azelaic acid, undecanedioic acid, dodecanedioic acid and the like. Among these, adipic acid is particularly preferable. The proportion of other dicarboxylic acids used is preferably 10 mol% or less of the total dicarboxylic acid, and more preferably 5 mol% or less of the total dicarboxylic acid. 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 of the total dicarboxylic acid, more preferably 5 mol% or less of the total dicarboxylic acid.

  The relative viscosity of the polyamide resin (A) (measuring conditions of 96% sulfuric acid, concentration 1 g / 100 ml, temperature 25 ° C.) is preferably 1.6 to 3.5, more preferably 1.7 to 3. Most preferably, it is 1.8 to 2.8. If the relative viscosity is too low, the mechanical strength may be insufficient, and if it is too high, the moldability tends to decrease.

[3. Organic nucleating agent (B)]
The polyamide resin composition in the present invention contains an organic nucleating agent (B).
Examples of organic nucleating agents include polyamide resins having a high crystallization speed such as polyamide 66, polyamide 46, polyamide 6T, and polyamide 9T, and polyamides having a high melting point such as polyamide 66 / 6T, polyamide 66 / 6I, and polyamide 66 / 6T / 6I. Examples thereof include xylylenediamine-based polyamide resins other than resins and polyamide resins (A). The above “I” indicates an isophthalic acid-derived component, and “T” indicates a terephthalic acid-derived component.
The xylylenediamine-based polyamide resin other than the polyamide resin (A) is a polyamide resin obtained by a polycondensation reaction between xylylenediamine, which is a raw material of the polyamide resin (A), and a dicarboxylic acid other than sebacic acid. Is a polymetaxylylene adipamide resin (MXD6) obtained from metaxylylenediamine and adipic acid, or a polyamide resin (polyamide) obtained by polycondensation of a mixed diamine and adipic acid of metaxylylenediamine and paraxylylenediamine MP6).
As the organic nucleating agent (B), polyamide 66 or polyamide MP6 is preferable, and polyamide 66 is particularly preferable because it is inexpensive and easily available, has a high crystallization rate, and has good fluidity.
The relative viscosity of the polyamide resin as component (B) (measuring conditions in 96% sulfuric acid, concentration 1 g / 100 ml, temperature 25 ° C.) is preferably 1 to 4, more preferably 1.8 to 3. 0.5, more preferably 2 to 3.2, and most preferably 2 to 3. Outside this range, the expression of the nucleating agent effect may be insufficient, the mechanical strength may be insufficient, and the moldability may be reduced.

  Since the crystallization speed of the polyamide resin (A) is considerably slower than other polyamide resins, in the present invention, the kind of the organic nucleating agent (B) is selected so as to satisfy the following conditions, and the blending amount thereof Is preferably adjusted.

  That is, first, the melting point of the organic nucleating agent (B) in the case of the polyamide resin composition (after the crystallization treatment described later) is higher than the melting point of the polyamide resin (A) by more than 50 ° C. It is preferable to select the organic nucleating agent (B). When the difference between the melting points of the two is 50 ° C. or less, when the polyamide resin composition is melted and cooled to obtain a molded product, the crystallization of the organic nucleating agent (B) becomes too slow, and the crystallization of the polyamide resin (A) The promotion effect may be insufficient. By setting it as the combination whose melting | fusing point difference exceeds 50 degreeC, the obtained molded article can be made into the thing of a high crystallinity degree. In addition, the molded article thus obtained is excellent in mechanical properties, and is excellent in that the mechanical properties are hardly lowered even when water is absorbed. A preferable melting point difference is 60 ° C. or more, and more preferably 70 ° C. or more.

  In order to make the melting point of the organic nucleating agent (B) higher than the melting point of the polyamide resin (A) by 50 ° C., a method of selecting the type of the polyamide resin (A) and the organic nucleating agent (B), or a polyamide resin What is necessary is just to employ | adopt the method of adjusting manufacturing conditions at the time of obtaining a composition, for example, conditions, such as temperature at the time of melt-kneading, time, and screw rotation speed.

  In the present invention, when the polyamide resin composition (after the crystallization treatment described later) is used, the crystallization temperature of the polyamide resin (A) and the crystallization temperature of the organic nucleating agent (B) The temperature difference is preferably 50 ° C. or less. By setting it as such a temperature difference, it becomes easy to crystallize an organic nucleating agent (B) at the temperature near the area | region where crystallization of a polyamide resin (A) occurs. That is, when the organic nucleating agent (B) is crystallized in a temperature range in which the polyamide resin (A) is easily crystallized, the crystallized organic nucleating agent (B) functions as a crystal nucleating agent for the polyamide resin (A), Crystallization of the polyamide resin (A) can be promoted, and the resulting molded product can have a high crystallinity. The temperature difference between the two is preferably 45 ° C. or less, more preferably 40 ° C. or less.

  In order to set the temperature difference between the crystallization temperature of the polyamide resin (A) and the crystallization temperature of the organic nucleating agent (B) to 50 ° C. or less, the types of the polyamide resin (A) and the organic nucleating agent (B) are selected. In addition, a method of preparing these contents and the amount of an inorganic nucleating agent such as boron nitride and talc to be added as necessary may be adopted.

In the present invention, the melting points of the polyamide resin (A) and the organic nucleating agent (B) are observed when the temperature is increased at a rate of 10 ° C./min in a nitrogen atmosphere in the differential scanning calorimetry (DSC) method. Defined as the peak top temperature of the endothermic peak. The crystallization temperature of the polyamide resin (A) and the organic nucleating agent (B) is the peak top of the exothermic peak observed when the temperature is lowered from the molten state at a rate of 20 ° C./min in a nitrogen atmosphere in DSC measurement. Is defined as the temperature of
Specifically, the polyamide resin composition pellets after the crystallization treatment described later are allowed to stand at room temperature for 12 hours, and then a 10 mg sample is cut out from the pellets and subjected to DSC. As conditions, the temperature was raised from 30 ° C. to the melting point of the organic nucleating agent (B) + about 30 ° C. at a rate of 10 ° C./min. Each melting point is obtained from the peak top temperature of the endothermic peak, and then the temperature is lowered to 30 ° C. at a rate of 20 ° C./min, and the exothermic peaks corresponding to the polyamide resin (A) component and the organic nucleating agent (B) component Each crystallization temperature is obtained from the temperature of the peak top.

  From the balance of crystallization temperature adjustment, moldability and physical properties, the content of the organic nucleating agent (B) is 0.1 to 50 parts by mass, preferably 1 to 100 parts by mass with respect to 100 parts by mass of the polyamide resin (A). 30 parts by mass, particularly preferably 3 to 30 parts by mass. By setting it as such a content ratio, it exists in the tendency which is excellent in a nucleating agent effect and the moldability at the time of shaping | molding is easy to be stabilized. When the content of the organic nucleating agent (B) is less than 0.1 parts by mass, it is difficult to obtain the expected effect of improving the crystallization rate. When the content is more than 50 parts by mass, the crystallization of the polyamide resin (A) It tends to be difficult to set the temperature difference between the temperature and the crystallization temperature of the organic nucleating agent (B) to 50 ° C. or less. In this case, the crystallization of the organic nucleating agent (B) itself proceeds quickly. The crystallization of the polyamide resin (A), which is the original purpose, is less likely to be promoted, and as a result, the mechanical strength such as rigidity may be lowered.

[4. Glass fiber]
The polyamide resin composition of the present invention preferably contains glass fibers in order to impart mechanical strength such as warpage performance and rigidity to the molded product. The content is preferably 10 to 250 parts by mass, more preferably 20 to 200 parts by mass, still more preferably 30 to 150 parts by mass, and particularly preferably 30 to 120 parts by mass with respect to 100 parts by mass of the polyamide resin (A). It is. If the glass fiber is less than 10 parts by mass, it may not be sufficient to exhibit strength and rigidity as a machine part, and if it exceeds 250 parts by mass, the melt viscosity of the polyamide resin composition becomes very high and injection molding is performed. It tends to be difficult to manufacture a molded product by such means.

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.

  The polyamide resin composition can further contain other fillers, such as inorganic fibers such as carbon fibers and ceramic fibers, metal fibers such as stainless steel fibers, and organic fibers such as liquid crystalline wholly aromatic polyamides. , Mica, potassium titanate, aluminum borate, titanium oxide, calcium carbonate, wollastonite and the like.

[5. Other additive ingredients]
In addition, the polyamide resin composition in the present invention includes a flame retardant, an anti-dripping agent, an antistatic agent, an antifogging agent, a lubricant, a plasticizer, a copper halide-based (as long as the purpose of the present invention is not impaired. For example, stabilizers such as copper iodide, copper chloride, copper bromide) and / or alkali metal halides (for example, potassium iodide, potassium bromide, etc.), hindered phenols, phosphites, etc. Antioxidants, mold release agents, inorganic nucleating agents, pigments, dyes, dispersants, ultraviolet absorbers, antibacterial agents and other well-known additives can be blended.

  It is preferable to contain a release agent for the purpose of improving mold release properties during molding, shortening the molding cycle, and obtaining a molded article having a good surface appearance. Examples of the release agent include higher fatty acid alkali (earth) metal salts, higher fatty acid (bis) amides, and polyolefin waxes. Higher fatty acid alkali (earth) metal salts and higher fatty acid (bis) amides are preferable.

The higher fatty acid alkali (earth) metal salt is an alkali metal salt of a higher fatty acid or an alkaline earth metal salt of a higher fatty acid, and the higher fatty acid has 10 to 30 carbon atoms, preferably 14 to 24 carbon atoms. This is preferable because of low dispersibility and good dispersibility.
Specific examples of higher fatty acids include, for example, caproic acid, capric acid, lauric acid, palmitic acid, stearic acid, behenic acid, lignoceric acid, montanic acid, oleic acid, linoleic acid, etc., preferably stearic acid, behenic acid An acid, a montanic acid, etc. are mentioned.

Examples of higher fatty acid alkali (earth) metal salts include alkali metal salts such as potassium salts and sodium salts of these higher fatty acids, and alkaline earth metal salts such as calcium salts and magnesium salts.
Specific examples of the higher fatty acid metal salt include calcium stearate, sodium stearate, magnesium stearate, calcium oleate, sodium oleate, calcium palmitate, sodium palmitate and the like.
Among these, magnesium stearate and calcium stearate are more preferable.

  These higher fatty acid alkali (earth) metal salts may be used alone or in a combination of two or more.

The higher fatty acid (bis) amide is an amide of a higher fatty acid or a bisamide of a higher fatty acid, and a compound obtained by a dehydration reaction between a higher fatty acid and / or a polybasic acid and a diamine is preferable. The higher fatty acid is preferably a saturated aliphatic monocarboxylic acid having 16 or more carbon atoms, for example, 16 to 30 carbon atoms, and specifically includes palmitic acid, stearic acid, behenic acid, montanic acid and the like.
The polybasic acid is a carboxylic acid of dibasic acid or more, for example, aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, sebacic acid, pimelic acid, azelaic acid, and aromatics such as phthalic acid and terephthalic acid. Examples thereof include dicarboxylic acids and alicyclic dicarboxylic acids such as cyclohexyl dicarboxylic acid and cyclohexyl succinic acid.
Examples of the diamine include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, metaxylylenediamine, tolylenediamine, paraxylylenediamine, phenylenediamine, and isophoronediamine.

Specific examples of the higher fatty acid (bis) amide include stearic acid amide, behenic acid amide, and montanic acid amide. Examples of the higher fatty acid bisamides include higher fatty acid bisamides obtained by reacting the above higher fatty acids with aliphatic diamines having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Stearylamide, ethylenebisstearylamide and the like can be mentioned. Of these, stearic acid amide and ethylene bisstearyl amide are preferable from the viewpoint of the effect of preventing the occurrence of burns and spears.
These higher fatty acid (bis) amides may be used alone or in combination of two or more.

  The content of the release agent is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1.2 parts by mass, and 0.07 to 0.8 parts per 100 parts by mass of the polyamide resin (A). Part by mass is more preferable. When the content is less than 0.01 parts by mass, it is difficult to obtain a sufficient effect of improving the releasability. When the content exceeds 2 parts by mass, the mechanical strength is reduced, the resin composition is melt kneaded or the resin composition When molding products, not only may the screw of the extruder or injection molding machine slip, resulting in insufficient kneading, but the mold deposit during molding will increase and the appearance of the molded product will deteriorate, resulting in poor productivity. Problems may occur.

  Furthermore, in the polyamide resin composition in the present invention, other resins than those described above may be blended unless the object of the present invention is impaired. Examples of such other resins include polyamide resins other than the polyamide resin (A) and the organic nucleating agent (B), polycarbonate resins, acrylic resins, polyester resins, polyphenylene ether resins, styrene resins, polyphenylene sulfide resins, and liquid crystals. Polyester resins, polyacetal resins, and polyesters, polyolefins, modified styrene-ethylene-butylene-styrene copolymers (SEBS), styrene-ethylene-propylene-styrene copolymers (SEPS), unmodified elastomers, etc. Can be mentioned. Moreover, as a thermosetting resin which can be mix | blended, a phenol resin, a melamine resin, a silicone resin, an epoxy resin etc. are mentioned, for example. When such other resins are contained, the content of other resins is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 30 parts by mass or less, with respect to 100 parts by mass of the polyamide resin (A). It is.

[6. Manufacture of polyamide resin composition pellets]
In order to produce such polyamide resin pellets, first, an extruder is used, and a polyamide resin (A) and an organic nucleating agent (B) are introduced into the hopper of the extruder, and if necessary, glass fibers and the like. Alternatively, the glass fibers are side-feeded, or alternatively, a premix obtained by mixing them in advance is put 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 molten state at 240 to 400 ° C., and cannot be cut by a pelletizer as it is, so it needs to be cooled and solidified to 150 ° 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.

[7. Crystallization process]
The obtained polyamide resin composition pellets are subjected to crystallization treatment. Sufficient crystallization treatment is performed so that the crystallization degree of the polyamide resin composition pellets is higher by 5% or more than the crystallization degree 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. Further, from the viewpoint of measurement stability at the time of molding by crystallization treatment, the content of the glass fiber (C) is more preferably 150 parts by mass or less with respect to 100 parts by mass of the polyamide resin (A), and 120 parts by mass. Part or less is particularly 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, then a 10 mg sample is cut out, and the differential scanning calorimetry (DSC) method is used. The temperature is raised at a rate of, 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 formula.
Crystallinity D ₁ (%) = [heat quantity of endothermic peak (J / g) −heat quantity of exothermic peak (J / g)] / [theoretical melting heat quantity (J / g) of polyamide resin (A)] × 100

When there are a plurality of endothermic peaks (for example, those derived from the polyamide resin (A) and those derived from the organic nucleating agent (B)), the heat amounts of the plurality of peaks are summed. The same applies to the case where there are a plurality of exothermic peaks, and the crystallinity D ₁ (%) obtained by the above formula is the total crystallinity of the plurality of peaks. The crystallinity D ₁ (%) in the above formula when the crystalline resin (a) other than the polyamide resin (A) and the organic nucleating agent (B) is contained is determined by the polyamide resin (A), the organic nucleating agent ( B) and the total crystallinity of the crystalline resin (a). In this case, an endothermic / exothermic peak derived from the polyamide resin (A), an endothermic / exothermic peak derived from the organic nucleating agent (B), and an endothermic / exothermic peak derived from the crystalline resin (a) are observed (respective endotherms). The endothermic peak in the above formula is the total 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. It is.
In addition, the theoretical heat of fusion in the above formula when there are a plurality of endothermic / exothermic peaks is the total heat obtained by multiplying the theoretical heat of fusion of each resin by its proportion. For example, in the case of a composition containing 90% by mass of the polyamide resin (A) having the theoretical heat of fusion Qa and 10% by mass of the organic nucleating agent (B) (for example, polyamide 66) having the theoretical heat of heat Qb, the theoretical melt The amount of heat is calculated as “Qa × 0.9 + Qb × 0.1”.

Here, the method for measuring the theoretical heat of fusion of each resin in the present invention will be described using an example of the polyamide resin (A).
The endothermic peak heat at the melting point of the polyamide resin (A) having various crystallinities is measured by DSC, and the obtained endothermic peak heat and crystallinity are 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. In addition, the crystallinity degree of the polyamide resin (A) used for DSC measurement can employ the density gradient tube method generally used, and can measure it based on JISK7112.
In the case of the organic nucleating agent (B) and other crystalline resins (a), the theoretical heat of fusion can be determined by the same method as described above.

Further, the crystallinity D ₂ (%) of the resin composition pellets subjected to crystallization treatment was also determined by cutting out a 10 mg sample after leaving the resin composition pellets after crystallization treatment at room temperature for 12 hours. It can be obtained by the same method as the measurement of ₁ .

  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.

[8. Molding method]
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.

<Materials used>
Polyamide resin (A) ("MXD10")
What was manufactured with the following method was used as a polyamide resin (A) in this invention.
In a reaction can, sebacic acid (Ito Seiyaku, TA grade) was heated and melted at 170 ° C., and then the contents were stirred while metaxylylenediamine (Mitsubishi Gas Chemical Co., Ltd., MXDA) was sebacic acid. The temperature was raised to 240 ° C. while gradually dropping so that the molar ratio of to was 1: 1. After completion of dropping, the temperature was raised to 260 ° C. After completion of the reaction, the contents were taken out in a strand shape and pelletized with a pelletizer. The obtained pellets were charged into a tumbler and subjected to solid phase polymerization under reduced pressure to obtain a polyamide resin having an adjusted molecular weight.
The obtained polyamide resin had a melting point of 190 ° C. measured by the method described below. The relative viscosity was 2.1.

Organic nucleating agent (B)
(B-1) Polyamide 66 (“PA66”)
The melting point measured by the following description method made by Toray Industries, Inc., trade name “Amilan (registered trademark) CM-3001N” was 262 ° C. The relative viscosity was 3.0.
(B-2) Polyamide MP6 (“MP6”)
What was manufactured with the following method was used.
730 g of adipic acid was charged into a 3 liter flask equipped with a stirrer, thermometer, reflux condenser, raw material dripping device, heating device, etc., and the temperature inside the flask was raised to 160 ° C. in a nitrogen atmosphere. The acid was melted. Into the flask, 680 g of mixed xylylenediamine containing 30 mol% of paraxylylenediamine and 70 mol% of metaxylylenediamine was successively added dropwise over about 2.5 hours. During this time, the reaction was continued with stirring while maintaining the internal temperature always above the melting point of the product, and the temperature was raised to 270 ° C. at the end of the reaction. 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 polyamide resin had a melting point of 258 ° C. measured by the method described below. The relative viscosity was 2.1.

Glass fiber (C)
(C-1) Glass fiber (“GFA”)
Chopped strand manufactured by Nippon Electric Glass Co., Ltd., trade name “ECS03T-275H”
(C-2) Glass fiber (“GFB”)
Owens Corning Manufacturing Chopped Strand Product name “CS03JAFT2”
Release agent (D)
Calcium montanate Made by Clariant Japan, trade name “Recommont CaV102”
Inorganic nucleating agent (E)
Talc, manufactured by Hayashi Kasei Co., Ltd., trade name "Micron White # 5000S"

(Examples 1-6, Comparative Examples 1-4)
<Method for producing resin composition>
(1) The above components (A), (B), (D) and (E) excluding glass fiber (C) are blended in the proportions (parts by mass) shown in Table 1, blended with a tumbler, biaxial After being charged from the base of an extruder (“TEM35B” manufactured by Toshiba Machine Co., Ltd.) and melted, when glass fiber (C) was contained, this was side fed to prepare a resin composition pellet. The temperature of the extruder was 280 ° C. up to the side feed part, 260 ° C. from the side feed part, and the discharge rate was 20 kg / hour.
(2) Next, the obtained pellets were put in a tank and kept at the temperature and time shown in Table 1 for crystallization treatment. Using the pellets thus obtained, the melting point and the crystallization temperature were measured by the methods described below.

<Evaluation method>
[Melting point and crystallization temperature]
The resin composition pellet obtained by the above method (2) was allowed to stand at room temperature for 12 hours, then a 10 mg sample was cut out, and the obtained sample was used under a nitrogen atmosphere using “DSC-6200” manufactured by Seiko Instruments Inc. The temperature was raised from 30 ° C. to 300 ° C. at a rate of 10 ° C./min, and the melting point was determined from the peak top temperature of the endothermic peaks corresponding to MXD10 (component (A)), PA66, and MP6 (component (B)). . After holding at 300 ° C. for 3 minutes, the temperature was decreased from 300 ° C. to 30 ° C. at a rate of 20 ° C./min, and the crystallization temperature was determined from the peak top temperature of the endothermic peaks corresponding to MXD10, PA66, and MP6 components.

[Crystallinity]
The resin composition pellets obtained by the above method (before and after the crystallization treatment) are allowed to stand at room temperature for 12 hours, then 10 mg of a sample is cut out, and the obtained sample is made by “DSC-” manufactured by Seiko Instruments Inc. 6200 "using a nitrogen atmosphere, the temperature was raised at a rate of 10 ° C. / min up to 30 to 300 ° C., according to the measurement method described above, the crystallization temperature D after treatment with the crystallization temperature D ₁ of the pre-crystallization process ₂ was measured.

[Weighing time and measurement]
Using the resin composition pellets after crystallization treatment obtained by the above method, using a FANUC injection molding machine “100T”, cylinder temperature setting 280 ° C. (uniform), weighing value 55 mm, weighing initial setting time 5 seconds A test piece having a thickness of 100 × 100 × 2 mm was molded into 20 shots under the conditions of a rotational speed of 80 rpm and a back pressure of 3 MPa, and an average value of the metering time was obtained from the metering time for each shot when molded under the above conditions. 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 seconds 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 seconds or more of the average value of the weighing time. X (Cannot be measured): The pellet is not sufficiently melted and unstable. Yes, the bite of the pellet into the screw was so bad that it could not be weighed.

  As can be seen from Examples 1 to 6, the melting point of the organic nucleating agent (B) after the crystallization treatment is higher than the melting point of the polyamide resin (A) by more than 50 ° C., and the crystallization degree after the crystallization treatment is high. It can be seen that the meterability is extremely stable by performing sufficient crystallization treatment so as to increase by 5% or more. On the other hand, in Comparative Examples 1 to 4 in which the crystallization after the crystallization treatment is insufficient and the increase in the degree of crystallinity is less than 5%, the meterability becomes very bad, and the average value of the measurement time is the initial setting time of 5 seconds. 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 measurement 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 xylylene sebacamide-based polyamide resin composition pellet excellent in molding stability during molding, in particular, measurement stability during injection molding or extrusion molding, is obtained. Therefore, it can be used to form molded products in a wide range of fields, such as automobile parts such as automobiles, general machine parts, precision machine parts, electronic / electric equipment parts, leisure sports equipment, and civil engineering building materials. The above usability is very high.

Claims (9)

Melting and kneading a polyamide resin composition containing 0.1 to 50 parts by mass of the organic nucleating agent (B) with respect to 100 parts by mass of the polyamide resin (A) obtained by polycondensation reaction of xylylenediamine and sebacic acid And a polyamide resin composition pellet obtained by extruding into a strand shape, cooling and cutting, and the pellet has a crystallinity degree after crystallization treatment sufficient to be higher by 5% or more than before crystallization treatment. A method for producing a polyamide resin composition pellet, characterized in that a crystallization treatment is performed, and the melting point of the organic nucleating agent (B) is higher than the melting point of the polyamide resin (A) by 50 ° C. The method for producing a polyamide resin composition pellet according to claim 1, wherein the temperature difference between the crystallization temperature of the polyamide resin (A) and the crystallization temperature of the organic nucleating agent (B) is 50 ° C or less. The method for producing a polyamide resin composition pellet according to claim 1 or 2, wherein the crystallization treatment is performed by holding the pellet in an air atmosphere at a temperature of 100 to 160 ° C for 15 minutes or more. The method for producing a polyamide resin composition pellet according to any one of claims 1 to 3, wherein the difference between the melting point of the polyamide resin (A) and the melting point of the organic nucleating agent (B) is 60 ° C or more. . The polyamide resin composition according to any one of claims 1 to 4, wherein the temperature difference between the crystallization temperature of the polyamide resin (A) and the crystallization temperature of the organic nucleating agent (B) is 40 ° C or less. Manufacturing method of food pellets. The method for producing a polyamide resin composition pellet according to any one of claims 1 to 5, wherein the organic nucleating agent (B) is polyamide 66. Furthermore, 10-250 mass parts of glass fibers (C) are contained with respect to 100 mass parts of polyamide resin (A), The polyamide resin composition pellet of any one of Claims 1-6 characterized by the above-mentioned. Manufacturing method. The crystallization treatment is performed by subjecting a polyamide resin composition pellet having a crystallization degree of 10 to 20% to a crystallization treatment so that the crystallization degree after the crystallization treatment is 23 to 35%. The manufacturing method of the polyamide resin composition pellet of any one of 1-7. The said crystallization process is a manufacturing method of the polyamide resin composition pellet of any one of Claims 1-8 performed after the solid-phase polymerization of a polyamide resin composition pellet.