JP5451522B2 - Method for producing long fiber reinforced polyamide resin composition - Google Patents

Description

  The present invention relates to a method for producing a long fiber reinforced polyamide resin composition.

  Generally, the short fiber reinforced polyamide resin is manufactured by a method in which short fibers such as polyamide resin and chopped strands are kneaded with an extruder. However, this method has a problem that glass fibers break during kneading in an extruder and cannot meet the demand for high mechanical properties.

  On the other hand, in recent years, it has been studied to lengthen the reinforcing fiber in order to sufficiently bring out the inherent performance of the fibrous reinforcing material (reinforcing fiber). For example, the long fiber reinforced polyamide resin is obtained by a pultrusion method in which a reinforcing fiber roving is used and a polyamide resin is impregnated into the reinforcing fiber roving while taking a fiber bundle in which the reinforcing fibers are bundled to obtain a polyamide resin strand. The long fiber reinforced polyamide resin composition obtained by this method is superior in mechanical strength as compared with the short fiber reinforced polyamide resin (see, for example, Patent Documents 1 and 2).

  On the other hand, as a method for obtaining resin pellets with high impregnation properties using a high molecular weight polyamide resin, for example, a method described in Patent Document 3 has been proposed. According to Patent Document 3, the melt viscosity of a polyamide resin when a glass fiber roving is impregnated with a polyamide resin is defined, and the glass fiber strand impregnated with the resin is pulled while being twisted. As a result, it is said that even a high molecular weight polyamide resin can provide a molded article having excellent resin impregnation properties and excellent mechanical strength and color tone.

  Further, as a method of using a high molecular weight polyamide resin, there has been proposed a method in which a fiber is first coated with a low molecular weight polymer such as a terpene phenol polymer, and then a high molecular weight polyamide resin is coated (for example, a patent). References 4 and 5). Thereby, it is said that a long fiber reinforced thermoplastic resin material with few molding defects such as gas burning and mold deposit can be obtained with high productivity.

  Further, the fiber bundle to which the polyamide resin is adhered is obtained by pulling a fiber bundle obtained by bundling a plurality of reinforcing fibers through the through hole of the die in which the through hole is formed together with the hot melted polyamide resin. There has been proposed a manufacturing method comprising a pellet manufacturing step for obtaining a pellet and a heating step for heating the pellet at a temperature lower than the melting point under low oxygen conditions (see, for example, Patent Document 6). According to this production method, it is said that a fiber-reinforced polyamide resin composition having improved mechanical strength and improved adhesive strength of polyamide resin glass fibers can be obtained.

JP-A 46-4545 JP 2006-16463 A International Publication No. 2007/105497 Japanese Patent No. 3774959 JP 2009-155363 A JP 2008-291192 A

  However, in the methods described in Patent Documents 1 and 2, in order to sufficiently impregnate the glass fiber roving with the resin, it is necessary to considerably reduce the melt viscosity of the polyamide resin during production. Therefore, in order to obtain highly impregnated resin pellets, a low molecular weight polyamide resin must be used. As a result, long-term characteristics such as vibration fatigue characteristics are insufficient. In addition, when a high molecular weight polyamide resin is used, the impregnation property of the resin is insufficient, or it is necessary to heat the polyamide resin at a temperature higher than the decomposition temperature in order to lower the melt viscosity of the polyamide resin. There is a problem that the strength is insufficient or the color tone of the pellet is deteriorated.

  Further, in the method described in Patent Document 3, since the glass fiber strand is pulled while being twisted, a molded product obtained by injection molding the resin pellet has insufficient fiber dispersion, and the appearance of the molded product is poor. Problems arise. Further, the methods described in Patent Documents 4 and 5 are not sufficient for exhibiting the performance of a high molecular weight polyamide resin because the composition contains a low molecular weight polymer.

  In the method described in Patent Document 6, it is suggested that heating at a temperature lower than the melting point of the polyamide resin improves the impregnation property of the pellets and improves the mechanical strength. No investigation has been made on the high molecular weight.

  Therefore, conventionally, it is required to produce a long fiber reinforced polyamide resin composition excellent in all of the color tone, impregnation property, long-term characteristics and appearance of a molded product of resin pellets.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a long fiber reinforced polyamide resin composition excellent in all of the color tone, impregnation property, long-term characteristics and appearance of a molded product of resin pellets.

  As a result of intensive studies to solve the above problems, the present inventors have used a polyamide resin having a specific sulfuric acid relative viscosity and pelletized a strand obtained by impregnating a molten polyamide resin into a fiber roving. Production of resin pellets and a step of increasing the molecular weight by heating the resin pellets having a specific end group concentration obtained in the above step at a temperature below the melting point of the polyamide resin and solid-phase polymerization The present inventors have found that the method can solve the above-mentioned problems and have completed the present invention.

That is, the present invention is as follows.
[1] A first step of pelletizing a strand obtained by impregnating a reinforced fiber roving with a molten polyamide resin to obtain a first resin pellet, and the first resin pellet below the melting point of the polyamide resin And a second step of obtaining a second resin pellet by high-molecular weight heating by solid phase polymerization, and the polyamide resin has a sulfuric acid relative viscosity (ηr) of 1.80 to 2.40. The terminal amino group concentration and the terminal carboxyl group concentration of the first resin pellet are both 50 meq / kg or more, and the sulfuric acid relative viscosity (ηr) of the second resin pellet is 2.60 to 5.00. A method for producing a certain long fiber reinforced polyamide resin composition.
[2] The method for producing a long fiber reinforced polyamide resin composition according to [1], wherein the sulfuric acid relative viscosity (ηr) of the second resin pellet is 2.60 to 3.20.
[3] The method for producing a long fiber reinforced polyamide resin composition according to [1] or [2], wherein the moisture content of the first resin pellet is 0.08 to 3.00 mass%.
[4] The method for producing a long fiber reinforced polyamide resin composition according to any one of [1] to [3], wherein the diameter of the first resin pellet is 2.00 to 2.60 mm.
[5] The method for producing a long fiber-reinforced polyamide resin composition according to any one of [1] to [4], wherein both the terminal amino group concentration and the terminal carboxyl group concentration of the polyamide resin are 50 meq / kg or more.
[6] The method for producing a long fiber reinforced polyamide resin composition according to any one of [1] to [5], wherein a concentration of the reinforcing fiber is 30 to 80% by mass with respect to a total amount of the long fiber reinforced polyamide resin composition. .

  ADVANTAGE OF THE INVENTION According to this invention, the long fiber reinforced polyamide resin composition excellent in all of the color tone of a resin pellet, an impregnation property, a long-term characteristic, and a molded article external appearance can be provided.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail.

[Production method]
The method for producing a glass long fiber reinforced polyamide resin composition (hereinafter also simply referred to as “resin composition”) of the present embodiment is obtained by pelletizing a strand obtained by impregnating a molten polyamide resin into a reinforcing fiber roving. The first step of obtaining the first resin pellets and the second step of obtaining the second resin pellets by heating the first resin pellets at a temperature below the melting point of the polyamide resin and increasing the molecular weight by solid phase polymerization And have.

  Hereinafter, the manufacturing method of a resin composition is demonstrated concretely.

  In the first step, first, a polyamide resin is melt-kneaded using a commonly used single-screw or twin-screw extruder. The melt kneading method may be a known method. The polyamide resin may contain various additives described below. Next, the polyamide resin in a molten state after melt-kneading is impregnated with reinforcing fiber roving, preferably by a pultrusion method, to obtain a strand.

The pultrusion method is not particularly limited as long as it is a known pultrusion method in which, for example, a continuous reinforcing fiber roving is impregnated with a molten thermoplastic resin.
Further, the polyamide resin in a molten state may be impregnated with reinforcing fiber roving, and the reinforcing fiber strand may be taken out while being twisted. Thereby, the strand excellent in the impregnation property of the polyamide resin is obtained.

  Next, the cooled strands are pelletized as necessary to obtain first resin pellets. The method of pelletizing is not particularly limited, and examples thereof include a method of cutting a strand in a direction intersecting the length direction of the strand by a known cutting machine.

  The moisture content of the first resin pellet obtained is lower than that of the second resin pellet described later from the viewpoint of preventing discoloration of the pellet during solid phase polymerization described later and performing high molecular weight in as short a time as possible. It needs to be set higher. A preferable range of the moisture content is 0.08 to 3.00% by mass, a more preferable range is 0.10 to 2.00% by mass, and a further preferable range is 0.20 to 1.00% by mass. When the moisture content is 0.08% by mass or more, discoloration prevention of the pellet can be efficiently realized. Moreover, when the moisture content is 3.00% by mass or less, an effect of shortening the molecular weight can be obtained. In addition, a moisture content is measured according to the method as described in the below-mentioned Example, and is based on the whole quantity of a 1st resin pellet.

  The method for controlling the moisture content within the above range is not particularly limited, but in the first step, the strand is cooled with cooling water, and the temperature of the cooling water at that time and the contact of the strand with the cooling water. It is convenient and preferable to control the amount of water by adjusting the time.

  The terminal amino group concentration and terminal carboxyl group concentration of the first resin pellet are both 50 meq / kg or more from the viewpoint of obtaining a high molecular weight composition after solid phase polymerization. Their concentration is more preferably 55 meq / kg or more, and still more preferably 60 meq / kg or more. These concentrations are measured according to the method described in the examples described later, and are based on the amount of polyamide resin contained in the first resin pellet.

  The method for controlling the terminal amino group concentration and the terminal carboxyl group concentration within the above ranges is not particularly limited. For example, a method of setting the terminal amino group concentration and terminal carboxyl group concentration of the polyamide resin used in the first step high. And / or a method of suppressing the decrease in the terminal amino group concentration and the terminal carboxyl group concentration by shortening the heat residence time of the polyamide resin during the impregnation in the first step.

  Here, “thermal residence time” means the residence time of the polyamide resin in the impregnation die when the reinforcing fiber roving is impregnated with the polyamide resin, and is represented by the formula (a) / (b). . Here, in the formula, (a) indicates the volume (unit: cc) of the impregnation die per strand, and (b) indicates the take-up speed (unit: cc / min) of the polyamide resin per strand. (B) can be calculated from the take-up linear velocity of the strand and the volume ratio of the polyamide resin contained in the unit length of the strand.

  In addition, the diameter of the first resin pellet is preferably 2.00 mm or more from the viewpoint of productivity of the first resin pellet, and 2.60 mm or less from the viewpoint of efficiently performing solid phase polymerization in the second step. Is preferable. A more preferable diameter is 2.10 to 2.50 mm, and a still more preferable diameter is 2.20 to 2.40 mm.

  In the second step, the first resin pellet obtained as described above is heated at a temperature not higher than the melting point of the polyamide resin to carry out solid phase polymerization, and the solid phase polymerization is carried out using a commonly used apparatus. Can be implemented. That is, it can be carried out batchwise with a corn type tumbler, or can be carried out continuously with a fluidized drying furnace. By heating the first resin pellet to a temperature not higher than the melting point of the polyamide resin, for example, by passing an inert gas such as nitrogen in an inert gas atmosphere, or by maintaining a reduced pressure state, Solid phase polymerization is performed to increase the molecular weight of the polyamide resin contained in the first pellet.

  A preferable heating temperature range in the case of solid phase polymerization is a range from a glass transition temperature (Tg) of the polyamide resin + 10 ° C. to a melting point (Tm) −10 ° C. of the polyamide resin. A more preferable heating temperature range is Tg + 20 ° C. to Tm−20 ° C. When the heating temperature is equal to or higher than the lower limit, solid phase polymerization can proceed smoothly.

  The resin composition according to the present embodiment is obtained as a second resin pellet by polymerizing the first resin pellet by solid phase polymerization as described above.

The sulfuric acid relative viscosity (ηr) of the resin composition according to this embodiment is 2.60 to 5.00 from the viewpoint of mechanical strength and long-term characteristics. The sulfuric acid relative viscosity (ηr) is more preferably 2.60 to 4.00, still more preferably 2.60 to 3.20. In the present specification, the sulfuric acid relative viscosity (ηr) is obtained from the following equation by measuring a sample solution at 25 ° C. using an Ostwald viscometer.
Sulfuric acid relative viscosity (ηr) = (sample solution dropping seconds) / (sulfuric acid solution dropping seconds)

  The sample solution used here is obtained by dissolving what is to be measured (herein, the second resin pellet) so as to have a concentration of 0.01 g / mL in a 96% sulfuric acid solution. Moreover, the sulfuric acid relative viscosity of a 2nd resin pellet is a sulfuric acid relative viscosity of what removed the reinforcement fiber from there. This relative viscosity of sulfuric acid can be controlled by adjusting the temperature and / or time of solid phase polymerization in the second step.

  Hereinafter, the polyamide resin and the reinforcing fiber roving which are raw materials used in the manufacturing method of the present embodiment will be described in detail.

[Polyamide resin]
A known polyamide can be used as the polyamide resin according to the present embodiment. Examples of such polyamide resins include polyamide 66, polyamide 6, polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide MXD6, polyamide (polyamide 6I) obtained by polymerizing hexamethylenediamine and isophthalic acid, and isophthalic acid. Homopolymers such as polyamide (polyamide PACMI) obtained by polymerizing acid and bis (3-methyl-4aminocyclohexyl) methane, polyamides obtained by polymerizing adipic acid, isophthalic acid and hexamethylenediamine (polyamide 66 / 6I copolymer), polyamide obtained by polymerizing adipic acid, terephthalic acid and hexamethylenediamine (polyamide 66 / 6T copolymer), polyamide obtained by polymerizing isophthalic acid, terephthalic acid and hexamethylenediamine. Polyamide 6I / 6T copolymer), polyamide obtained by polymerizing adipic acid, isophthalic acid, terephthalic acid and hexamethylenediamine (polyamide 66 / 6I / 6T copolymer), terephthalic acid and 2,2,4-trimethyl Polyamide obtained by polymerizing hexamethylenediamine and 2,4,4-trimethylhexamethylenediamine (polyamide TMDT copolymer), polyamide obtained by polymerizing terephthalic acid and nonanediamine (polyamide 9T), isophthalic acid and terephthalic acid , Hexamethylenediamine and bis (3-methyl-4aminocyclohexyl) methane, and a copolymerized polyamide, and isophthalic acid, terephthalic acid, hexamethylenediamine, bis (3-methyl-4aminocyclohexyl) methane, Copolymer poly formed by polymerizing A mixture of bromide and polyamide 6, and a mixture of polyamide MXD6 and polyamide 66.

  Among these, it is preferable to use polyamide 66 as the polyamide resin from the balance of long-term characteristics and appearance of the molded product.

  The relative viscosity (ηr) of sulfuric acid of the polyamide resin used in the first step is 1.80 to 2.40 in order to obtain sufficient impregnation of the resin into the glass fiber roving by a known pultrusion method. . The preferable range of the sulfuric acid relative viscosity (ηr) is 1.90 to 2.30, and the more preferable range is 2.00 to 2.20.

  The terminal amino group concentration and terminal carboxyl group concentration of the polyamide resin used in the first step are both 50 meq / kg or more in order to achieve high polymerization and high molecular weight by solid phase polymerization in the second step. It is preferable that Their concentration is more preferably 55 meq / kg or more, and still more preferably 60 meq / kg or more. These concentrations are measured according to the method described in the examples described later, and are based on the total amount of the polyamide resin.

[Reinforcing fiber roving]
The reinforcing fiber roving according to the present embodiment is not particularly limited as long as it is a roving in which continuous fibers of reinforcing fibers are converged, but in order to improve the adhesion between the reinforcing fibers and the polyamide resin, the reinforcing fibers Is preferably subjected to a surface treatment such as a coupling agent. The reinforcing fiber is not particularly limited as long as it is used for reinforcing ordinary resins, and for example, glass fiber, carbon fiber, metal fiber and organic fiber can be used. Glass fiber is most widely used. The content ratio of the glass fiber in the reinforcing fiber is preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

  The blending amount of the reinforcing fiber in the resin composition of the present embodiment is preferably 30 to 80% by mass or more based on the total amount of the resin composition from the viewpoint of mechanical strength. The blending amount of the reinforcing fibers is more preferably 35 to 75% by mass, and further preferably 40 to 70% by mass.

  Reinforcing fibers for polyamide resin that are preferably used in the present embodiment are those that have been surface-treated with a sizing agent for polyamide resin. The sizing agent here may contain a sizing component for so-called sizing and a surface treatment component for the purpose of adhesion between the polyamide resin. The constituent of the sizing agent is not particularly limited. For example, a preferable sizing agent includes a main component, ie, 50% by mass or more, of a copolymer of maleic anhydride and an unsaturated monomer and a silane coupling agent from the viewpoint of improving mechanical properties. More preferably, these components are used.

  Specific examples of the copolymer of maleic anhydride and unsaturated monomer constituting the sizing agent include styrene, α-methylstyrene, butadiene, isoprene, chloroprene, 2,3-dichlorobutadiene, 1,3- Mention may be made of copolymers of unsaturated monomers such as pentadiene and cyclooctadiene with maleic anhydride. Among them, butadiene or a copolymer of styrene and maleic anhydride is particularly preferable. Further, two or more of these monomers may be used as one copolymer monomer. Alternatively, for example, a mixture of a maleic anhydride / butadiene copolymer and a maleic anhydride / styrene copolymer may be used as a mixture. The copolymer of maleic anhydride and unsaturated monomer preferably has a weight average molecular weight of 2000 or more. Further, the ratio of maleic anhydride and unsaturated monomer is not particularly limited. Furthermore, as a sizing agent, in addition to the copolymer, an acrylic acid copolymer or a urethane polymer may be used in combination.

  As a silane coupling agent which is another suitable component constituting the sizing agent, a silane coupling agent usually used for surface treatment of glass fibers is preferable, and an amino group-containing silane coupling agent is more preferable. Specific examples of the silane coupling agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, and N-β (aminoethyl). Amino group-containing silane coupling agents such as aminopropyltrimethoxysilane and N-β (aminoethyl) aminopropyltriethoxysilane; γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, Epoxy group-containing silane coupling agents such as γ-glycidoxypropyltriethoxysilane; γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ- Methacryloxypropyl Methacryloxy group-containing silane coupling agents such as silane; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (beta-methoxyethoxy) vinyl-containing silane coupling agents such as silane. These silane coupling agents can be used alone or in combination of two or more.

  Of these, amino group-containing silane coupling agents are particularly preferable from the viewpoint of affinity with polyamide resin, and among them, γ-aminopropyltriethoxysilane and N-β (aminoethyl) γ-amino are particularly preferable. Propyltriethoxysilane is preferred. The ratio of the maleic anhydride copolymer and the silane coupling agent used is preferably a ratio of 0.01 to 20 parts by mass of the latter with respect to 100 parts by mass of the former from the viewpoint of providing a relatively good balance of physical properties. Usually, a maleic anhydride copolymer and a silane coupling agent are mixed in an aqueous solvent and used as a sizing agent. If necessary, a surfactant, a lubricant, a softening agent, an antistatic agent or the like may be added to the sizing agent.

  Further, the diameter (average fiber diameter) of the monofilament of the reinforcing fiber is not particularly limited. However, the diameter is preferably 5 μm or more from the viewpoint of obtaining highly impregnated resin pellets, and preferably 20 μm or less from the viewpoint of improving mechanical properties. The diameter is more preferably 10 to 18 μm from the viewpoint of improving the mechanical properties of the resin composition.

  Further, the fiber length of the reinforcing fiber in the first and second resin pellets of the present embodiment is a weight average fiber length, and is preferably 5 mm or more from the viewpoint of a balance between mechanical strength and long-term characteristics, and molding fluidity. In view of the above, it is preferably 15 mm or less. The fiber length is more preferably 6 to 14 mm, still more preferably 7 to 13 mm. Moreover, the fiber length of the reinforcing fiber in the first and second resin pellets is longer than the pellet length. Here, the “pellet length” means a distance between the end portions of the pellet in a direction orthogonal to the radial direction of the resin pellet corresponding to the radial direction of the strand, and a cutting machine (pelletizer) as described later. When pelletizing by cutting by means of, it means the distance between the cut surfaces.

In addition, the measurement of a weight average fiber length is performed as follows. That is, first, resin pellets are heated to burn organic components such as polyamide resin. Thereafter, the remaining reinforcing fibers were transferred onto a slide glass, observed under an optical microscope, and the length of 400 arbitrarily selected reinforcing fibers was measured using an image analyzer. Find the length.
Weight average fiber length = Σ (L _{(GF) i} ² ) / ΣL _{(GF) i}
Here, the length of each fiber is L _{(GF) 1} , L _{(GF) 2} ,..., L _{(GF) 400} .

  Further, the number of TEXes of roving used for obtaining one strand is not particularly limited, but is preferably 500 to 8000 TEX, more preferably 1000 to 7000 TEX, and further preferably 1500 from the viewpoint of productivity. ~ 6000TEX.

  Moreover, it is possible to mix | blend various additives with the resin composition of this embodiment as desired. Specific examples of additives include heat stabilizers for polyamides such as copper compounds and phosphorus compounds, antioxidants such as hindered phenols and hindered amines, light stabilizers such as manganese compounds, and nucleating agents such as talc and boron nitride. , Lubricants such as higher fatty acid metal salts represented by metal stearates, mineral fillers such as calcium carbonate, wollastonite, kaolin, calcined kaolin and mica, plasticizers, antistatic agents, flame retardants, dyes, pigments, Examples include thermoplastic resins other than polyamide.

  The resin composition is obtained in the form of pellets, but the pellets may be further processed according to the application.

  The resin composition of this embodiment is suitably used as a raw material for various molded products. The method for producing a molded product from the resin composition may be the same as the method for producing a molded product from known resin pellets. As the molded product according to the present embodiment, for example, a front end module, an engine cover, a radiator tank, a car heater tank, a water valve, a water pump, a radiator pipe, an intake manifold, a timing chain cover, an oil pan, an anti-vibration bush, etc. Examples include automobile parts and electrical / electronic parts.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said this embodiment. The present invention can be variously modified without departing from the gist thereof.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited only to these Examples. In addition, the raw material and the measuring method which were used for the Example and the comparative example are shown below.

[raw materials]
1. Polyamide resin (A)
a-1: Polyamide 66 resin (sulfuric acid relative viscosity (ηr): 2.10, terminal amino group concentration: 65 meq / kg, terminal carboxyl group concentration: 130 meq / kg, melting point (Tm): 260 ° C., glass Transition temperature (Tg): 66 ° C)
a-2: Polyamide 66 resin (sulfuric acid relative viscosity (ηr): 2.10, terminal amino group concentration: 20 meq / kg, terminal carboxyl group concentration: 175 meq / kg, melting point (Tm): 260 ° C., glass Transition temperature (Tg): 66 ° C)
a-3: Polyamide 66 resin (product name “Leona (registered trademark) 1300S”, manufactured by Asahi Kasei Chemicals Corporation, sulfuric acid relative viscosity (ηr): 2.64, terminal amino group concentration: 40 meq / kg, terminal carboxyl group concentration: 80 meq / kg, melting point: 260 ° C., glass transition temperature (Tg): 66 ° C.)
a-4: Polyamide 66 resin, sulfuric acid relative viscosity (ηr): 2.40, terminal amino group concentration: 55 meq / kg, terminal carboxyl group concentration: 90 meq / kg, melting point (Tm): 260 ° C., glass Transition temperature (Tg): 66 ° C)
a-5: Polyamide 66 resin, sulfuric acid relative viscosity (ηr): 1.80, terminal amino group concentration: 90 meq / kg, terminal carboxyl group concentration: 180 meq / kg, melting point (Tm): 260 ° C., glass Transition temperature (Tg): 66 ° C)
a-6: Polyamide 66 resin, sulfuric acid relative viscosity (ηr): 2.10, terminal amino group concentration: 98 meq / kg, terminal carboxyl group concentration: 98 meq / kg, melting point (Tm): 260 ° C., glass Transition temperature (Tg): 66 ° C)
a-7: Polyamide 66 resin, sulfuric acid relative viscosity (ηr): 2.10, terminal amino group concentration: 130 meq / kg, terminal carboxyl group concentration: 65 meq / kg, melting point (Tm): 260 ° C., glass Transition temperature (Tg): 66 ° C)

2. Reinforcing fiber (b)
b-1: Glass fiber roving (product name “ER4301H”, manufactured by Chongqing International Composites Co., Ltd., fiber diameter: 17 μm, roving TEX number: 1200 TEX)

[Measurement of Sulfuric Acid Relative Viscosity (ηr) of Resin Composition]
About the obtained second resin pellet, using the solution obtained by dissolving the remaining components excluding the glass fiber therefrom in a 96% sulfuric acid aqueous solution to a concentration of 0.01 g / mL, The sulfuric acid relative viscosity (ηr) was measured and used as the sulfuric acid relative viscosity (ηr) of the resin composition.

[Measurement of terminal carboxyl group concentration [COOH]]
The sample was dissolved in benzyl alcohol at 170 ± 5 ° C. and titrated with 0.1N sodium hydroxide to measure the terminal carboxyl group concentration. Phenolphthalein was used as an indicator.

[Measurement of terminal amino group concentration [NH ₂ ]]
The sample was dissolved in phenol and subjected to potentiometric titration with 0.02N hydrochloric acid to measure the terminal amino group concentration.

[Measurement of moisture content of first resin pellet]
The moisture content of the first resin pellet was measured according to JIS K 7251 using a moisture meter (product name “CA-06 type”, Karl Fischer method, manufactured by Mitsubishi Chemical Corporation), and the moisture content was measured. Asked.

[Measurement of flexural modulus and flexural strength]
Using an injection molding machine (product name “FN-3000”, screw diameter 40 mm, manufactured by Nissei Plastic Industry Co., Ltd.), cylinder temperature 295 ° C., mold temperature 80 ° C., injection pressure 50 MPa, injection time 5 seconds, cooling time The resin pellets were injection-molded into a flat plate under molding conditions of 25 seconds and a screw speed of 200 rpm to obtain a flat plate (15 cm × 15 cm, thickness 4 mm). A test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm was obtained by cutting the flat plate so that the bending elastic modulus and bending strength in the flow direction during injection molding could be measured. Next, in accordance with ISO 178, the test piece was subjected to an evaluation of bending elastic modulus and bending strength under the conditions of a crosshead speed of 5 mm / min and a span of 64 mm by an autograph (manufactured by Shimadzu Corporation, product name “AG-5000D”). Measurements were made.

[Measurement of appearance of molded product]
Ten flat plates obtained by the above [Measurement of flexural modulus and bending strength] were visually observed. When no lump of glass fiber was observed on the surface, “◯”, lump of glass fiber was 1 The case where it was observed also in a place was evaluated as “x”.

[Vibration fatigue resistance]
Using an injection molding machine (product name “FN-3000”, screw diameter 40 mm, manufactured by Nissei Plastic Industry Co., Ltd.), cylinder temperature 295 ° C., mold temperature 80 ° C., injection pressure 65 MPa, injection time 5 seconds, cooling time The resin pellets were injection-molded into a flat plate under molding conditions of 25 seconds and a screw speed of 200 rpm to obtain a flat plate (15 cm × 15 cm, thickness 3 mm). An ASTM No. 1 test piece was cut out from the flat plate in a direction perpendicular to the flow direction during injection molding. About the obtained test piece, according to JIS K7118, using a hydraulic servo fatigue tester (product name “EHF-50-10-3”, manufactured by Kakinomiya Seisakusho Co., Ltd.), under an environment of 120 ° C. and a frequency of 20 Hz. A tensile load was applied with a sine wave, and the stress that caused the load to break 1 million times was determined. The higher the fracture stress, the better the vibration fatigue resistance.

[Measurement of impregnation]
One end of the resin pellet (length 10 mm) (strand cut surface) is a color indicator methyl red propanol solution (50 mL of methyl red propanol saturated solution is adjusted to pH to adjust the pH) For 30 minutes. Thereafter, the penetration state of the color indicator in the length direction of the resin pellet was observed. Observation was made on 10 arbitrarily selected resin pellets. Count the number of resin pellets in which the penetration of the color indicator of 2 mm or more is seen in the length direction of the resin pellets. The case of 0 is “◯”, the case of 1-5 is “Δ”, 6-10 The case was evaluated as “x”. If the glass fiber roving is sufficiently impregnated with resin, the propanol solution of methyl red will not penetrate into the resin pellets. The smaller the number of pellets in which penetration of 2 mm or more is observed, the better the resin impregnation into the glass fiber roving.

[Measurement of color tone]
The color tone of the resin pellet was measured according to JIS K 7105. The color tone was evaluated with respect to a standard white plate using a color difference meter (product name “ND-300A”, manufactured by Nippon Denshoku Co., Ltd., projection lens diameter 30 mm) with a measurement area of 30 mm in diameter. The YI value indicates yellowishness, and a smaller numerical value means whiter and better.
The color tone of the resin pellets was measured by filling the pellets in a dedicated glass holder.

[Example 1]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-1) was melted at a melting temperature of 280 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP” -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 40 cm), and then cut with a pelletizer to obtain a first resin pellet (c-1). In the obtained first resin pellet (c-1) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes. Here, “immersion length” means the length of the strand immersed in the cooling water in the water-cooled bath.

  The water content of the first resin pellet (c-1) is 0.20% by mass, the sulfuric acid relative viscosity is 2.10, the terminal amino group concentration is 63 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
10 kg of the first resin pellet (c-1) is filled into a 20-liter corn type tumbler apparatus, solid phase polymerization is performed at 180 ° C. for 8 hours under a nitrogen stream, and a second sulfuric acid relative viscosity of 2.64 is obtained. Resin pellet (resin composition) (d-1) was obtained.
Table 1 shows the evaluation results of the second resin pellet (d-1).

[Example 2]
(First step)
As in Example 1, except that the bundle of glass fiber roving (b-1) to be introduced was changed from three to one and the nozzle diameter of the impregnation die was changed from 2.4 mm to 1.4 mm. Resin pellet (c-2) was obtained. In the obtained first resin pellet (c-2) (length 10 mm, diameter 1.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 6 minutes.
The water content of the first resin pellet (c-2) is 0.55% by mass, the sulfuric acid relative viscosity is 2.10, the terminal amino group concentration is 55 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-2) in the same manner as in Example 1, and a second resin pellet (resin composition) (d-2) having a relative viscosity of sulfuric acid of 2.64 was obtained. Obtained.
The evaluation results of the second resin pellet (d-2) are shown in Table 1.

[Example 3]
(First step)
The first glass fiber roving (b-1) bundle was changed from 3 to 2 and the nozzle diameter of the impregnation die was changed from 2.4 mm to 2.0 mm. Resin pellet (c-3) was obtained. In the obtained first resin pellet (c-3) (length 10 mm, diameter 2.0 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 3 minutes.
The water content of the first resin pellet (c-3) is 0.45% by mass, the sulfuric acid relative viscosity is 2.10, the terminal amino group concentration is 57 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-3) in the same manner as in Example 1, and a second resin pellet (resin composition) (d-3) having a relative viscosity of sulfuric acid of 2.64 was obtained. Obtained.
The evaluation results of the second resin pellet (d-3) are shown in Table 1.

[Example 4]
(First step)
Except that the bundle of glass fiber roving (b-1) to be introduced was changed from 3 to 4 and the nozzle diameter of the impregnation die was changed from 2.4 mm to 2.9 mm, the same procedure as in Example 1 was carried out. Resin pellets (c-4) were obtained. In the obtained first resin pellet (c-4) (length 10 mm, diameter 2.9 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 30 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 3 minutes.
The moisture content of the first resin pellet (c-4) is 0.35% by mass, the sulfuric acid relative viscosity is 2.10, the terminal amino group concentration is 57 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-4) in the same manner as in Example 1 except that the solid phase polymerization time was changed from 8 hours to 15 hours, and the relative viscosity of sulfuric acid was 2.64. A second resin pellet (resin composition) (d-4) was obtained.
The evaluation results of the second resin pellet (d-4) are shown in Table 1.

[Example 5]
(First step)
A first resin pellet (c-5) was obtained in the same manner as in Example 1 except that the immersion length in the water-cooled bath was changed from 40 cm to 15 cm. In the obtained first resin pellet (c-5) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes.
The water content of the first resin pellet (c-5) is 0.08% by mass, the sulfuric acid relative viscosity is 2.10, the terminal amino group concentration is 63 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-5) in the same manner as in Example 1, and a second resin pellet (resin composition) (d-5) having a relative viscosity of sulfuric acid of 2.64 was obtained. Obtained.
Table 1 shows the evaluation results of the second resin pellet (d-5).

[Example 6]
(First step)
A first resin pellet (c-6) was obtained in the same manner as in Example 1 except that the distance of the water-cooled bath was changed from 40 cm to 10 cm. In the obtained first resin pellet (c-6) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes.
The water content of the first resin pellet (c-6) is 0.05% by mass, the sulfuric acid relative viscosity is 2.10, the terminal amino group concentration is 63 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-6) in the same manner as in Example 1, and a second resin pellet (resin composition) (d-6) having a relative viscosity of sulfuric acid of 2.64 was obtained. Obtained.
Table 1 shows the evaluation results of the second resin pellet (d-6).

[Example 7]
(First step)
A first resin pellet (c-7) was obtained in the same manner as in Example 1 except that the immersion length in the water-cooled bath was changed from 40 cm to 500 cm. In the obtained first resin pellet (c-7) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes.
The water content of the first resin pellet (c-7) is 2.80% by mass, the relative viscosity of sulfuric acid is 2.10, the terminal amino group concentration is 63 meq / kg, and the terminal carboxyl group concentration is 130 meq / kg. there were.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-7) in the same manner as in Example 1 except that the solid phase polymerization time was changed from 8 hours to 25 hours, and the relative viscosity of sulfuric acid was 2.80. A second resin pellet (resin composition) (d-7) was obtained.
The evaluation results of the second resin pellet (d-7) are shown in Table 1.

[Example 8]
(First step)
A first resin pellet (c-1) similar to that in Example 1 was obtained.

(Second step)
The solid phase polymerization was performed on the first resin pellet (c-1) in the same manner as in Example 1 except that the solid phase polymerization time was changed from 8 hours to 20 hours, and the relative viscosity of sulfuric acid was 3.20. A second resin pellet (d-8) was obtained.
The evaluation results of the second resin pellet (d-8) are shown in Table 1.

[Comparative Example 1]
The 1st resin pellet (c-1) in Example 1 was made into the resin composition. The evaluation results are shown in Table 1.
The resin composition of this comparative example was inferior in vibration fatigue characteristics as compared with the examples.

[Comparative Example 2]
(First step)
Resin pellets (c-8) were obtained in the same manner as in the first step of Example 1, except that the polyamide resin (a-1) was changed to the polyamide resin (a-2). In the obtained resin pellet (c-8) (length 10 mm, diameter 2.4 mm), the glass fiber concentration was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes.
The moisture content of the resin pellet (c-8) was 0.20% by mass, the sulfuric acid relative viscosity was 2.10, the terminal amino group concentration was 16 meq / kg, and the terminal carboxyl group concentration was 175 meq / kg.

(Second step)
The resin pellet (c-8) was subjected to solid phase polymerization in the same manner as in Example 1 to obtain a resin pellet (resin composition) (d-9) having a relative viscosity of sulfuric acid of 2.32. Thereafter, solid phase polymerization was further performed, but the terminal amino group was consumed, so that the relative viscosity of sulfuric acid did not change from 2.32.
The evaluation results of the resin pellet (d-9) are shown in Table 1.
The resin composition of this comparative example was inferior in vibration fatigue characteristics as compared with the examples.

[Comparative Example 3]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-3) was melted at a melting temperature of 290 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP” -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 10 cm), and then cut with a pelletizer to obtain resin pellets (c-9). In the obtained resin pellet (c-9) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 10 m / min, and the heat residence time of the polyamide resin in the impregnation die was 12 minutes.

  The moisture content of the resin pellet (c-9) was 0.65% by mass, the sulfuric acid relative viscosity was 2.45, the terminal amino group concentration was 40 meq / kg, and the terminal carboxyl group concentration was 110 meq / kg.

(Second step)
A resin having a relative viscosity of 2.64 sulfuric acid was obtained by subjecting the resin pellet (c-9) to solid phase polymerization in the same manner as in Example 1 except that the solid phase polymerization time was changed from 8 hours to 2.5 hours. Pellets (resin composition) (d-10) were obtained.
The evaluation results of the resin pellet (d-10) are shown in Table 1.
The resin composition of this comparative example was inferior to the impregnation property and color tone of the pellet as compared with the example.

[Comparative Example 4]
Resin pellets (resin composition) (c-9) obtained by drying the resin pellets (c-9) obtained in the first step of Comparative Example 3 with a dehumidifying dryer to reduce the moisture content to 0.05% by mass. ') Got. The evaluation results of the resin pellet (c-9 ′) are shown in Table 1.
The resin composition of this comparative example was not only inferior to the color tone and impregnation property of the pellets, but also inferior in vibration fatigue properties as compared with the examples.

[Comparative Example 5]
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-1) was melted at a melting temperature of 290 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP” -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 5 cm), and then cut with a pelletizer to obtain a resin pellet (resin composition) (c-10). In the obtained resin pellet (c-10) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10.6 mm. Moreover, about a pair of roller which picks up this strand, the strand was twisted by making it pass between the rollers arrange | positioned by shifting the angle of a mutual roller axis | shaft and making it oppose. The strand take-up speed at this time was 60 m / min, and the twist pitch was 24 mm. The heat residence time of the polyamide resin in the impregnation die was 2 minutes.

The moisture content of the resin pellet (c-10) was 0.08% by mass, and the relative viscosity of sulfuric acid was 2.64.
Table 1 shows the evaluation results of the resin pellet (c-10).
The resin composition of this comparative example resulted in inferior appearance of the molded product as compared with the example.

[Example 9]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-1) was melted at a melting temperature of 310 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP” -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of five glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.6 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 20 cm), and then cut with a pelletizer to obtain resin pellets (c-11). In the obtained resin pellet (c-11) (length 10 mm, diameter 2.6 mm), the glass fiber concentration (blending amount) was 65 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was 2.2 minutes.

  The moisture content of the resin pellet (c-11) was 0.20% by mass, the sulfuric acid relative viscosity was 2.10, the terminal amino group concentration was 63 meq / kg, and the terminal carboxyl group concentration was 130 meq / kg.

(Second step)
In the same manner as in Example 1, solid phase polymerization was performed on the resin pellet (c-11) to obtain a resin pellet (resin composition) (d-11) having a relative viscosity of sulfuric acid of 2.64.
Table 2 shows the evaluation results of the resin pellet (d-11).

[Comparative Example 6]
The 1st resin pellet (c-11) in Example 9 was made into the resin composition. The evaluation results are shown in Table 2.
The resin composition of this comparative example was inferior in vibration fatigue characteristics as compared with the examples.

[Example 10]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-4) was melted at a melting temperature of 310 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP”). -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 40 cm), and then cut with a pelletizer to obtain resin pellets (c-12). In the obtained resin pellet (c-12) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 40 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 3 minutes.
The moisture content of the resin pellet (c-12) was 0.13% by mass, the sulfuric acid relative viscosity was 2.35, the terminal amino group concentration was 52 meq / kg, and the terminal carboxyl group concentration was 90 meq / kg.

(Second step)
The resin pellet (c-12) was subjected to solid phase polymerization in the same manner as in Example 1 except that the time of solid phase polymerization was changed from 8 hours to 4 hours, and resin pellets having a relative viscosity of sulfuric acid of 2.67 ( Resin composition) (d-12) was obtained.
The evaluation results of the resin pellet (d-12) are shown in Table 3.

[Example 11]
(First step)
In the same manner as in Example 10, a first resin pellet (c-12) was obtained.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-12) in the same manner as in Example 10 except that the time of solid phase polymerization was changed from 4 hours to 32 hours, and the relative viscosity of sulfuric acid was 4.56. A second resin pellet (d-13) was obtained.
Table 3 shows the evaluation results of the second resin pellet (d-13).

[Example 12]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-5) was melted at a melting temperature of 310 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP” -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 80 cm), and then cut with a pelletizer to obtain resin pellets (c-13). In the obtained resin pellet (c-13) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 80 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 1.5 minutes.
The moisture content of the resin pellet (c-13) was 0.13% by mass, the sulfuric acid relative viscosity was 1.80, the terminal amino group concentration was 90 meq / kg, and the terminal carboxyl group concentration was 180 meq / kg.

(Second step)
The resin pellet (c-13) was subjected to solid phase polymerization in the same manner as in Example 1 except that the solid phase polymerization time was changed from 8 hours to 12 hours. Resin composition) (d-14) was obtained.
Table 3 shows the evaluation results of the resin pellet (d-14).

[Comparative Example 7]
(First step)
In the same manner as in Example 10, a first resin pellet (c-12) was obtained.

(Second step)
Solid phase polymerization was performed on the first resin pellet (c-12) in the same manner as in Example 10 except that the solid phase polymerization time was changed from 4 hours to 40 hours, and the relative viscosity of sulfuric acid was 5.10. A second resin pellet (d-15) was obtained.
An attempt was made to evaluate the second resin pellet (d-15). However, since the relative viscosity of sulfuric acid was extremely high, it was impossible to obtain a test piece by injection molding, and various characteristics could not be evaluated.

[Comparative Example 8]
The 1st resin pellet (c-12) in Example 10 was made into the resin composition. The evaluation results are shown in Table 3.
The resin composition of this comparative example was inferior in vibration fatigue characteristics as compared with the examples.

[Comparative Example 9]
The first resin pellet (c-13) in Example 12 was used as the resin composition. The evaluation results are shown in Table 3.
The resin composition of this comparative example was inferior in vibration fatigue characteristics as compared with the examples.

[Example 13]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), the polyamide resin (a-6) was melted at a melting temperature of 280 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP” -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 40 cm), and then cut with a pelletizer to obtain resin pellets (c-14). In the obtained resin pellet (c-14) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes.
The moisture content of the resin pellet (c-14) was 0.20% by mass, the sulfuric acid relative viscosity was 2.10, the terminal amino group concentration was 95 meq / kg, and the terminal carboxyl group concentration was 98 meq / kg.

(Second step)
In the same manner as in Example 1, solid phase polymerization was performed on the resin pellet (c-14) to obtain a resin pellet (resin composition) (d-16) having a sulfuric acid relative viscosity of 2.64.
Table 4 shows the evaluation results of the resin pellets (d-16).

[Example 14]
(First step)
Using a twin screw extruder (product name “ZSK25”, manufactured by Coperion), a polyamide resin (a-7) is melted at a melting temperature of 280 ° C. and a screw rotation speed of 300 rpm, and a long fiber reinforced resin production apparatus (product name “KOSLFP”). -212 ", manufactured by Kobe Steel, Ltd.) and supplied to an impregnation die (volume: 375 cc) equipped with a resin impregnation roller. On the other hand, a bundle of three glass fiber rovings (b-1) was introduced from the roving table into an impregnation die filled with molten polyamide resin. A bundle of glass fiber rovings impregnated with polyamide resin in the impregnation die was continuously pulled out from the nozzle (nozzle diameter: 2.4 mm) of the impregnation die to obtain one strand. Subsequently, the strand was cooled and solidified in a water-cooled bath (immersion length: 40 cm), and then cut with a pelletizer to obtain resin pellets (c-15). In the obtained resin pellet (c-15) (length 10 mm, diameter 2.4 mm), the glass fiber concentration (blending amount) was 50 mass%, and the fiber length of the glass fiber was 10 mm. The strand take-up speed at this time was 60 m / min, and the heat residence time of the polyamide resin in the impregnation die was about 2 minutes.
The moisture content of the resin pellet (c-15) was 0.13% by mass, the sulfuric acid relative viscosity was 2.10, the terminal amino group concentration was 127 meq / kg, and the terminal carboxyl group concentration was 65 meq / kg.

(Second step)
In the same manner as in Example 1, solid phase polymerization was performed on the resin pellet (c-15) to obtain a resin pellet (resin composition) (d-17) having a relative viscosity of sulfuric acid of 2.64.
Table 4 shows the evaluation results of the resin pellets (d-17).

Claims (6)

A first step of pelletizing a strand obtained by impregnating a molten polyamide resin into a reinforcing fiber roving to obtain a first resin pellet; and the first resin pellet at a temperature not higher than the melting point of the polyamide resin. A second step of heating and increasing the molecular weight by solid phase polymerization to obtain a second resin pellet,
The polyamide resin has a sulfuric acid relative viscosity (ηr) of 1.80 to 2.40, and both the terminal amino group concentration and the terminal carboxyl group concentration of the first resin pellet are 50 meq / kg or more, The manufacturing method of the long fiber reinforced polyamide resin composition whose sulfuric acid relative viscosity ((eta) r) of 2 resin pellets is 2.60-5.00.   The method for producing a long fiber reinforced polyamide resin composition according to claim 1, wherein the sulfuric acid relative viscosity (ηr) of the second resin pellet is 2.60 to 3.20.   The manufacturing method of the long fiber reinforced polyamide resin composition of Claim 1 or 2 whose moisture content of a said 1st resin pellet is 0.08-3.00 mass%.   The manufacturing method of the long fiber reinforced polyamide resin composition as described in any one of Claims 1-3 whose diameter of a said 1st resin pellet is 2.00-2.60 mm.   The manufacturing method of the long fiber reinforced polyamide resin composition as described in any one of Claims 1-4 whose terminal amino group density | concentration and terminal carboxyl group density | concentration of the said polyamide resin are both 50 milliequivalent / kg or more.   The manufacturing method of the long fiber reinforced polyamide resin composition as described in any one of Claims 1-5 whose density | concentration of the said reinforced fiber with respect to the whole quantity of the said long fiber reinforced polyamide resin composition is 30-80 mass%.