JP5846971B2 - Sandwich molding - Google Patents

Description

  The present invention relates to a sandwich molded body.

  Polyamide resins are widely used as metal substitute materials because their molded products have excellent mechanical properties. When imparting high rigidity and heat resistance to a polyamide molded body, a polyamide resin composition containing a specific amount of glass fiber as a fibrous reinforcing material is usually used. In the polyamide resin composition reinforced with glass fiber, various molding methods for enhancing the reinforcing effect have been proposed. For example, in a sandwich molded body in which the primary material is the skin part and the secondary material is the core part, the primary material is made of long fiber reinforced resin, and the secondary material is made of short fiber reinforced resin, thereby improving its strength. Has been proposed (Patent Document 1).

  However, the molded article of Patent Document 1 does not have practically sufficient performance such as deformation and breakage of a molded product when used as a mechanical member that requires a great load over a long period of time. In addition, since the sandwich molded body of Patent Document 1 has low mechanical properties in a high temperature environment, as a part used under severe conditions such as a high temperature and high humidity environment exceeding 100 ° C. in an automobile engine room, It is difficult to use in place of metal parts.

  In addition, in the polyamide resin composition reinforced with glass fiber, a combination of various weathering agents and carbon black (Patent Document 2) or a combination of carbon black and nigrosine in order to impart weather resistance. (Patent Document 3) is presented. However, in the case of using carbon black in this way, the weather resistance is improved, but the mechanical strength of the polyamide resin composition is lowered, and when it is used as a mechanical member that takes a heavy load over a long period of time, it is deformed. In addition, it does not have practically sufficient performance such as breakage of molded products.

Japanese Patent No. 2972024 JP 2004-107536 A JP-A-11-279399

  An object of the present invention is to provide a sandwich molded body with little reduction in mechanical strength even under a high temperature environment.

The inventor has found that sandwich molded articles using specific polyamide resin compositions for the skin part and the core part are excellent in weather resistance, and have a low decrease in mechanical strength even in a high temperature environment. The present invention has been reached.
That is, the gist of the present invention is as follows.

  (1) A sandwich having a structure in which a skin portion is formed on the surface of the core portion, and the core portion is sandwiched between the skin portions, and satisfies the following (I) to (IV) simultaneously: Molded body.

(I) The polyamide resin composition (A) constituting the skin portion contains the polyamide resin (a) and the glass fiber (x), and the mixing ratio (a / x) is 45/55 to 70 by mass ratio. / 30.
(II) The polyamide resin composition (B) constituting the core portion contains the polyamide resin (b) and the glass fiber (y), and the mixing ratio (b / y) is 35/65 to 55 by mass ratio. / 45.
(III) Melting viscosity ηa measured at a melting point of polyamide resin composition (A) + 30 ° C. and shear rate 1000 s ⁻¹ , and a melting point ηa measured at polyamide resin composition (B) + 30 ° C. and shear rate 1000 s ⁻¹ The melt viscosity ηb is
1 <log ηa / log ηb <1.4
It is.
(IV) The content X of the glass fiber (x) contained in the polyamide resin composition (A) and the content Y of the glass fiber (y) contained in the polyamide resin composition (B) are:
X ≦ Y
It is.

  (2) The sandwich molded article according to (1), wherein the volume ratio of the skin part is 40 to 70% of the total volume.

  (3) The polyamide resin composition (A) further contains 0.1 to 3 parts by mass of carbon black (c) with respect to 100 parts by mass in total of the polyamide resin (a) and the glass fiber (x). A sandwich molded article according to (1) or (2), which is characterized.

  (4) The polyamide resin composition (B) further contains 0.03 to 3 parts by mass of a higher fatty acid metal salt (d) with respect to 100 parts by mass in total of the polyamide resin (b) and the glass fiber (y). (1) to (3) according to any one of the above-mentioned sandwich molded articles.

  According to the present invention, since a specific polyamide resin composition is used for each of the skin portion and the core portion, it is possible to provide a sandwich molded body with little decrease in mechanical strength even under a high temperature environment.

(A) shows the schematic perspective view of the cross section perpendicular | vertical to the resin flow direction of one Embodiment of the sandwich molded object of this invention, (b) is explanatory drawing for calculating the thickness of the sandwich molded object of (a). Show. The schematic perspective view of the cross section parallel to the resin flow direction of the sandwich molding of FIG. 1 is shown. (A) is a schematic perspective view of another embodiment of the sandwich molded product of the present invention, (b) is a schematic diagram of a cross section perpendicular to the resin flow direction of the sandwich molded product of (a), (c) FIG. 4 is an explanatory diagram for calculating the thickness of the sandwich molded body of (a). (A) is a schematic front view of still another embodiment of the sandwich molded body of the present invention, (b) is a schematic plan view of the sandwich molded body of (a), and (c) is a sandwich of (a). The schematic of the cross section perpendicular | vertical to the resin flow direction of a molded object is shown, (d) shows explanatory drawing for calculating the thickness of the sandwich molded object of (a).

  The sandwich molded body of the present invention has a core part and a skin part formed on the surface of the core part. Specifically, the sandwich molded body of the present invention has a core portion sandwiched between skin portions, and has a skin portion on the peripheral surface of the core portion at least in a cross section perpendicular to the resin flow direction during molding. . Specifically, for example, as shown in FIG. 1A, the sandwich molded body of the present invention has a skin portion A on the peripheral surface of the core portion B in a cross section perpendicular to the resin flow direction L at the time of molding. Is formed. Furthermore, as shown in FIG. 2, the sandwich molded body of the present invention may have a skin portion A formed on the peripheral surface of the core portion B even in a cross section parallel to the resin flow direction L during molding. Furthermore, in the sandwich molded body of the present invention, the skin portion A may or may not be formed on the end surface C in the resin flow direction L (see, for example, FIG. 2).

  In the sandwich molded body of the present invention, the polyamide resin composition (A) constituting the skin portion contains the polyamide resin (a), and the polyamide resin composition (B) constituting the core portion contains the polyamide resin (b). To do. These polyamide resins (a) and (b) are polyamides having an amide bond in the main chain. For example, polyε-capramide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene Adipamide (nylon 66), polyhexamethylene sebamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecamethylene adipamide (nylon 116), polyundecanamide (nylon 11), Polydodecanamide (nylon 12), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene terephthalamide (nylon 6T), polynonamethylene terephthalamide (nylon 9T), polymetaxylylene adipamide (nylon MXD6), polyhexamethylene Telefu Luamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), polycaproamide / polyhexamethylene isophthalamide copolymer (nylon 6 / 6I), poly Hexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polytrimethylhexamethylene terephthalamide (nylon TMDT), Polybis (4-aminocyclohexyl) methane dodecamide (nylon PACM12), polybis (3-methyl-4-aminocyclohexyl) methane dodecamide (nylon dimethyl PACM1) ), And polyamide copolymers comprising at least two kinds of structures different amide component of the amide component constituting these polyamide (monomer), as well as mixtures thereof. Among these, nylon 6 or nylon 66 is particularly preferably used alone or in combination from the viewpoints of strength, moldability, and economy.

  In the sandwich molded body of the present invention, the polyamide resin composition (A) constituting the skin portion contains glass fibers (x), and the polyamide resin composition (B) constituting the core portion contains glass fibers (y). To do. As these glass fibers (x) and (y), for example, generally supplied glass fibers can be appropriately used. Specific examples thereof include glass fibers made of glass materials such as E glass (Electrical glass), C glass (Chemical glass), A glass (Alkali glass), S glass (High strength glass), and alkali-resistant glass. Can be mentioned.

  Glass fibers (x) and (y) are produced by a known method for producing glass fibers. For example, it can be obtained by melt spinning the glass material. The glass fibers (x) and (y) may be used in the form of so-called chopped strands that are bundled with a sizing agent and collected into a certain length by collecting the bundled glass fiber strands as necessary. preferable. As the sizing agent, a coupling agent can be used from the viewpoint of adhesion to the matrix resin and uniform dispersibility. Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, and a zirconia coupling agent. Especially, it is preferable to use a silane coupling agent, and it is especially preferable to use an aminosilane coupling agent and a glycidylsilane coupling agent.

  The fiber diameter of the glass fibers (x) and (y) is preferably 4 to 13 μm, and more preferably 7 to 11 μm. When the fiber diameter is less than 4 μm, it is difficult to quantitatively supply the polyamide resins (a) and (b) with melt-kneading, and the mechanical properties of the polyamide resin compositions (A) and (B) are insufficiently dispersed. There is a tendency that the strength, that is, the mechanical strength of the molded body is lowered. On the other hand, when the fiber diameter exceeds 13 μm, the reinforcing effect is reduced, and the mechanical strength of the polyamide resin compositions (A) and (B) is lowered. The average fiber length of the glass fibers (x) and (y) is preferably 1 to 10 mm, and more preferably 1.5 to 6 mm. When the average fiber length is less than 1 mm, the remaining fiber length in the pellet obtained by melt-kneading is short, and the mechanical strength when a sandwich molded body is obtained becomes low. On the other hand, when the average fiber length exceeds 10 mm, the glass fiber in the sandwich molded body does not remain with a certain fiber length or more, so that the reinforcing effect is saturated and does not contribute to the improvement of the mechanical strength. In addition, the quantitative supply becomes unstable during melt kneading, and the operability tends to deteriorate.

  The average fiber length / fiber diameter (L / D) of the glass fibers (x) and (y) is preferably 80 to 2500 from the viewpoint of improving the mechanical strength of the molded article at room temperature and high temperature. More preferably, it is 140-850.

The sandwich molded body of the present invention is required to satisfy the following requirements (I) to (IV) at the same time.
(I) The polyamide resin composition (A) constituting the skin portion contains the polyamide resin (a) and the glass fiber (x), and the mixing ratio (a / x) is 45/55 by mass ratio. 70/30.
(II) The polyamide resin composition (B) constituting the core portion contains the polyamide resin (b) and the glass fiber (y), and the mixing ratio (b / y) is 35/65 to 55 by mass ratio. / 45.
(III) Melting viscosity ηa measured at a melting point of polyamide resin composition (A) + 30 ° C. and shear rate 1000 s ⁻¹ , and a melting point ηa measured at polyamide resin composition (B) + 30 ° C. and shear rate 1000 s ⁻¹ The melt viscosity ηb is
1 <log ηa / log ηb <1.4.
(IV) The content rate X of the glass fiber (x) contained in the polyamide resin composition (A) and the content rate Y of the glass fiber (y) contained in the polyamide resin composition (B),
X ≦ Y.

  Regarding the requirement (I), the polyamide resin composition (A) constituting the skin part of the sandwich molded body of the present invention comprises 45 to 70% by mass of the polyamide resin (a) and 30 to 55% by mass of the glass fiber (x). It is necessary to contain. Preferably, they are polyamide resin (a) 50-65 mass% and glass fiber (x) 35-50 mass%. When the content of the glass fiber (x) is less than 30% by mass, the mechanical strength of the sandwich molded product particularly in a high temperature environment is lowered. On the other hand, if it exceeds 55% by mass, the fracture strain of the polyamide resin composition (A) tends to be small, so that the mechanical strength of the sandwich molded product particularly at room temperature is lowered.

  Regarding the requirement (II), the polyamide resin composition (B) constituting the core part of the sandwich molded body of the present invention comprises a polyamide resin (b) of 35 to 55% by mass and a glass fiber (y) of 45 to 65% by mass. It is necessary to contain. Preferably, they are polyamide resin (b) 40-55 mass% and glass fiber (y) 45-60 mass%. When the glass fiber (y) content is less than 45% by mass, the strength of the resulting polyamide resin composition (B) is low, so that the mechanical strength of the sandwich molded article at room temperature and high temperature is lowered. On the other hand, if it exceeds 65% by mass, the dispersibility of the glass fiber (y) in the polyamide resin tends to decrease, and the fracture strain of the polyamide resin composition (B) tends to be small. Decreases.

Regarding the requirement (III), in the sandwich molded body of the present invention, for the polyamide resin composition (A), the melting point + 30 ° C., the melt viscosity ηa measured at a shear rate of 1000 s ⁻¹ , and the polyamide resin composition (B), Melting viscosity ηb measured at melting point + 30 ° C. and shear rate 1000 s ⁻¹ is
1 <log ηa / log ηb <1.4
It must be.

In the present invention, as will be described later, after the polyamide resin composition (A) constituting the skin part and the polyamide resin composition (B) constituting the core part are heated and melted, they are simultaneously flowed, cooled and solidified. By doing so, a sandwich molded body is obtained. Alternatively, after the polyamide resin composition (A) is fluidized, the polyamide resin composition (B) is fluidized and cooled and solidified to obtain a sandwich molded body. At this time, the skin portion should not be extremely thin, or a part of the skin portion should not be broken and the inner core portion should not protrude. In order to prevent the occurrence of such a situation, as described above, between the melt viscosity ηa of the polyamide resin composition (A) and the melt viscosity ηb of the polyamide resin composition (B),
1 <log ηa / log ηb <1.4
It is necessary to have a relationship.
1.05 <log ηa / log ηb <1.3
It is more preferable that there is a relationship of

  When logηa / logηb ≦ 1, the thickness of the skin portion of the sandwich molded body is reduced due to the flow of the polyamide resin composition (B) that forms the core portion having a high melt viscosity, and the mechanical properties at room temperature are particularly low. Strength decreases. When logηa / logηb ≧ 1.4, the melt viscosity of the polyamide resin composition (B) forming the core portion is low and the flow is disturbed, so that the core portion is not uniformly formed and the entire sandwich molded body is machined. The mechanical strength is reduced.

  The difference in melting points of the polyamide resin compositions (A) and (B) constituting the skin part and the core part is preferably as small as possible because it is easy to satisfy the requirement (III). The following is preferable.

  Regarding requirement (IV), the glass fiber (x) content X in the polyamide resin composition (A) and the glass fiber (y) content Y in the polyamide resin composition (B) are X ≦ Y. It is necessary. When X> Y, the skin portion is hardly distorted when an external force is applied, and a large stress is generated, so that the skin portion is easily broken, and sufficient mechanical strength as a sandwich molded body cannot be ensured.

  By satisfying the requirements (I) to (IV), the glass fibers of the skin part and the core part of the sandwich molded body are oriented (the flow direction of the molten resin in the molding process coincides with the fiber axis direction of the glass fibers). The orientation region of the glass fiber is wide and the degree of orientation can be increased. As a result, the strain resistance of the sandwich molded body against external force can be increased, and the mechanical strength of the resulting sandwich molded body can be effectively increased.

  The volume ratio of the skin portion of the sandwich molded body to the entire sandwich molded body is preferably 40 to 70%, and preferably 45 to 65%. When the volume ratio of the skin part occupying the entire sandwich molded body is less than 40%, the mechanical strength may be lowered. When this volume ratio exceeds 70%, particularly in a high temperature environment of 100 ° C. or more. The mechanical strength may be greatly reduced. By setting the volume ratio of the skin portion of the sandwich molded body to 40 to 70% of the entire sandwich molded body, the skin portion and the core portion constituting the sandwich molded body can be formed in a preferable thickness and a uniform state. .

  It is preferable that the polyamide resin composition (A) further contains carbon black (c). By containing carbon black (c), the crystallinity of the resulting polyamide resin composition is improved, and the mechanical strength of the sandwich molded product, particularly in a high temperature environment, can be increased. Moreover, it also has the effect that weather resistance can be provided. Carbon black can be contained not only in the polyamide resin composition (A) but also in the polyamide resin composition (B). However, the inclusion of only the polyamide resin composition (A) makes it possible to clearly determine the interface between the skin part and the core part of the sandwich molded article, and also has an effect of easily confirming the uniformity between the skin part and the core part. . A known carbon black can be used. The pH of carbon black is preferably 8 or more, more preferably 9 or more. When the pH is less than 8, the deterioration of the polyamide resin is promoted and the strength thereof may be lowered. The pH of carbon black here is the pH of an aqueous suspension in which 1 g of carbon black is dispersed in 20 ml of distilled water. Further, the oxygen-containing group concentration of carbon black is preferably less than 0.5% by mass, and more preferably less than 0.4% by mass. When the oxygen-containing group concentration exceeds 0.5% by mass, the polyamide resin may be deteriorated or the adhesion between the polyamide resin and the glass fiber may be inhibited, leading to a decrease in strength of the polyamide resin composition. The oxygen-containing group concentration can be calculated from the weight loss when carbon black is heated at 950 ° C. for 7 minutes.

The DBP absorption amount and primary particle diameter of carbon black are not particularly limited. However, DBP absorption amount is preferably 40~200cm ³ / 100g, and more preferably 60~170cm ³ / 100g. The primary particle diameter is preferably 10 to 40 nm, and more preferably 15 to 30 nm. If the DBP absorption amount or the primary particle diameter is out of the above range, the dispersibility of the carbon black is lowered, and the mechanical strength of the sandwich molded article may be lowered or the weather resistance may not be satisfied. The DBP absorption can be measured based on JIS K6217, and the primary particle diameter can be obtained as an arithmetic average diameter by an electron microscope.

  The content of carbon black (c) in the polyamide resin composition (A) is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass in total of the polyamide resin (a) and the glass fiber (x). More preferably, it is 0.2-2 mass parts. If it is less than 0.1 mass part, there exists a tendency for the crystallinity improvement of a polyamide resin composition to become inadequate. On the other hand, when the amount exceeds 3 parts by mass, the affinity between the polyamide resin composition and the glass fiber tends to be hindered. As a result, the fracture strain of the polyamide resin composition is lowered, and the mechanical strength of the sandwich molded body is lowered. Sometimes.

  The polyamide resin composition (B) preferably further contains a higher fatty acid metal salt (d). By containing the higher fatty acid metal salt (d), the dispersion of the polyamide resin and the glass fiber is improved, and the glass fiber contained in the core part is oriented in the flow direction in the vicinity of the skin part of the sandwich molded body. Therefore, the mechanical strength of the sandwich molded body can be increased. A well-known thing can be used as a higher fatty acid metal salt (d). Among them, arachidic acid having 20 carbon atoms, 22 behenic acid, 24 lignoceric acid, and 28 montanic acid metal salt are preferable, and a mixture thereof may also be used. A metal salt of behenic acid is particularly preferable. Examples of metals generally include sodium, calcium, magnesium, lithium, aluminum, zinc, potassium, barium, and the like. Among these metals, sodium, calcium, and magnesium are highly versatile and can be preferably used.

  The content of the higher fatty acid metal salt (d) in the polyamide resin composition (B) is 0.03 to 3 parts by mass with respect to 100 parts by mass in total of the polyamide resin (b) and the glass fiber (y). Preferably, it is 0.1-2 mass parts. If it is less than 0.03 parts by mass, the effect of improving the dispersion of the glass fibers and improving the orientation in the flow direction is poor, and the mechanical strength of the sandwich molded product may not be sufficiently increased. On the other hand, when the amount exceeds 3 parts by mass, a large amount of decomposition gas is generated during the molding process of the polyamide resin composition (B), causing voids in the molded body, and the mechanical strength of the sandwich molded body decreases. There is. On the other hand, it is not preferred that the polyamide resin composition (A) contains a higher fatty acid metal salt. When a higher fatty acid metal salt is blended in the polyamide resin composition (A), the melt viscosity during the molding process of the polyamide resin composition (A) is greatly reduced, and the shear rate near the mold interface is reduced, Since the orientation of the glass fiber becomes weak, the mechanical strength of the sandwich molded body may be lowered.

  The skin part and / or the core part may be, for example, a heat stabilizer, an antioxidant, a crystal nucleating agent, a pigment, an anti-coloring agent, a weathering agent, and a plasticizer as long as the properties are not impaired. Additives may be included. These additives may be independently contained in the pellet for forming the skin part, may be contained in the pellet for forming the core part, or may be used by mixing with the pellets during the molding process. .

  Examples of the heat stabilizer and the antioxidant include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and mixtures thereof. Examples of the crystal nucleus material include talc.

  When the above-mentioned additive is contained in the skin part, the total content of the additive is preferably 5% by mass or less with respect to the total amount of the resin composition constituting the skin part.

  When the above-mentioned additives are contained in the core part, the total content of the additives is the total amount of the resin composition constituting the core part from the viewpoint of not impairing the mechanical properties of the polyamide resin in the core part. On the other hand, 5 mass% or less is suitable.

  In addition, the skin part and / or the core part may contain a reinforcing material other than glass fibers and / or a flame retardant as required, as long as the properties are not impaired. These may be independently contained in the pellet for forming the skin part, may be contained in the pellet for forming the core part, or may be used by mixing with the pellets during the molding process.

  Examples of reinforcing materials other than glass fibers include talc, mica, and wollastonite. Examples of the flame retardant include halogen-based flame retardants, non-halogen flame retardants such as phosphorus, magnesium hydroxide, and aluminum hydroxide.

  In the case where a reinforcing material other than glass fiber and / or a flame retardant are contained in the skin part or the core part, the content of the reinforcing part other than glass fiber in order to exert the function as the reinforcing material or flame retardant It is preferable that it is 10-30 mass% in total with a flame retardant.

  The skin portion and / or the core portion contain a thermoplastic resin other than the polyamide resins (a) and (b) (hereinafter referred to as “other thermoplastic resins”) as long as the effects of the present invention are not impaired. May be. Examples of other thermoplastic resins include polybutadiene, butadiene / styrene copolymer, acrylic rubber, ethylene / propylene copolymer, ethylene / propylene / butadiene copolymer, natural rubber, chlorinated butyl rubber, and chlorinated polyethylene. Elastomers or their modified products such as maleic anhydride, styrene / maleic anhydride copolymer, styrene / phenylmaleimide copolymer, polyethylene, polypropylene, polystyrene, syndiotactic polystyrene, butadiene / acrylonitrile copolymer, polyvinyl chloride , Polyethylene terephthalate, polyacetal, polyvinylidene fluoride, polysulfone, polyphenylene sulfide, polyether sulfone, phenoxy resin, polyphenylene ether, polymethyl methacrylate , Polyether ketone, polycarbonate, polytetrafluoroethylene, polyarylate, and the like. Other thermoplastic resins may be contained in the pellet for forming the skin part, may be contained in the pellet for forming the core part, or may be used by mixing with these pellets at the time of molding.

  When other thermoplastic resin is contained in the skin part or the core part, the content of the other thermoplastic resin is not limited to the mechanical properties of the polyamide resin. It is preferable that it is 10 mass% or less with respect to the resin composition whole quantity, and it is more preferable that it is 5 mass% or less.

  The thickness of the skin part of the sandwich molded body is not particularly limited, and may be appropriately set according to the use of the sandwich molded body. The thickness of the skin part is preferably 0.5 to 3 mm, for example, and more preferably 1.0 to 2.5 mm. The thickness of the skin part with respect to the total thickness of the sandwich molded body is preferably 10% or more and 60% or less, and more preferably 15% or more and 55% or less. The thickness of the skin portion does not need to be constant, and may vary depending on the shape of the sandwich molded body.

  The thickness of the core part of the sandwich molded body is not particularly limited, and may be set as appropriate according to the use of the sandwich molded body. The thickness of the core part is preferably 3 to 20 mm, for example, and more preferably 3 to 15 mm. The thickness of the core portion does not need to be constant, and may vary depending on the shape of the sandwich molded body.

  The overall thickness of the sandwich molded body is not particularly limited, but is preferably 8 mm or more, particularly preferably 8 to 20 mm, and more preferably 8 to 15 mm. Since a thick molded body having a thickness of 8 mm or more tends to generate voids and the like, it is generally difficult to improve mechanical properties, particularly bending strength. However, even when the sandwich molded body of the present invention has such a thick shape, voids and the like are hardly generated, and an improvement in bending strength in a high temperature environment can be easily achieved.

  The sandwich molded body can be manufactured by manufacturing the pellet for forming the skin part and the pellet for forming the core part, and then supplying the obtained pellets as a primary material and a secondary material in a so-called sandwich molding method, respectively. .

  The method for producing the skin portion forming pellets or the core portion forming pellets is not particularly limited. For example, a method of kneading using a twin-screw extrusion kneader is preferably used. Specifically, polyamide resin is supplied from the upstream side of the cylinder, and an inorganic filler such as glass fiber or carbon fiber is side-fed at the middle part of the cylinder. Thereafter, the resin composition can be drawn from the die in a strand shape, cooled and solidified, and cut with a pelletizer to obtain pellets. Such a method is economically suitable.

  The sandwich molding method is a molding method generally performed in the field of synthetic resins. As a specific sandwich molding method, an injection molding method or a sandwich molding method by an extrusion molding method can be selected.

  In the sandwich molding method by the injection molding method, the skin portion forming pellet is used as a primary material, and the core portion forming pellet is used as a secondary material. Specifically, first, the molten primary material is injected into a mold. Next, the molten secondary material is injected into the mold with a time difference. At this time, the injection of the primary material may be stopped or may be injected together with the secondary material without stopping. Then, the secondary material is stopped, the primary material is injected again, and the gate is closed with the primary material. During this time, either the primary material or the secondary material is always injected, and the flow of the resin does not stop in the mold. By doing so, the secondary material flows in the primary material melted in the mold, the primary material is spread and forms a skin part, and the gate is also closed by the primary material. A primary material is formed on all surfaces. Finally, the material in the mold is sufficiently cooled / solidified to obtain a sandwich molded body. As shown in FIGS. 1 and 2, the sandwich molded body thus obtained has a sandwich structure in which the secondary material (core part B) is sandwiched or encased in the primary material (skin part A). Have.

  As a sandwich molding method by an extrusion molding method, a film-shaped or sheet-shaped sandwich molded body can be obtained by co-extrusion molding with a layer configuration of primary material / secondary material / primary material. Such a sandwich molded body can be cut into a required size and used in the form of a film or a sheet. Alternatively, the obtained film-shaped or sheet-shaped sandwich molded body can be used after being heated and then shaped into a required shape by vacuum forming, pressure forming, punching forming, or the like. .

  The sandwich molded body of the present invention can take various shapes depending on the application. For that purpose, at the time of molding, the shape of the mold may be a shape corresponding to the desired shape of the sandwich molded body.

  For example, the sandwich molded body of the present invention may have a flat plate shape as shown in FIGS.

  For example, the sandwich molded body of the present invention may have a convex shape as shown in the perspective view of FIG. In FIG. 3A, L is the resin flow direction during molding. A schematic diagram of a cross section perpendicular to the resin flow direction L is shown in FIG. A is a skin part and B is a core part.

  For example, the sandwich molded body of the present invention may have a dumbbell shape as shown in the front view of FIG. 4A and the plan view of FIG. 4 (a) and 4 (b), L is the direction of resin flow during molding. A schematic diagram showing a cross section perpendicular to the resin flow direction L is shown in FIG. That is, FIG. 4C is a cross-sectional view taken along the XY cut plane in FIGS. 4A and 4B. A is a skin part and B is a core part.

  The thickness of the above-mentioned sandwich molded body is that the cross-sectional area of the sandwich molded body is Sk in the cross section perpendicular to the resin flow direction L during molding, and the layer formed by the skin portion and the core portion in the cross section of the sandwich molded body. When the center line, which is a line passing through the substantially central portion of m, is m, and the length of the center line m in the cross section of the sandwich molded body is p, it can be expressed by Sk / p.

  For example, the cross-sectional area Sk (shaded area), the center line m (broken line), the length p of the center line m, and the thickness t when the sandwich molded body has a flat plate shape as shown in FIGS. As shown in FIG.

  Further, for example, a cross-sectional area Sk (shaded area) and a center line m (broken line) in the case where the sandwich molded body has a convex shape as shown in FIGS. 3A and 3B are shown in FIG.

  For example, FIG. 4D shows a cross-sectional area Sk (shaded area) and a center line m (broken line) when the sandwich molded body has a dumbbell shape as shown in FIGS.

  The average fiber length / fiber diameter (L / D) of the glass fibers (x) and (y) in the sandwich molded body is 80 to 2500 from the viewpoint of improving the mechanical strength under normal temperature and high temperature environment. Is preferable, and it is more preferable that it is 140-850.

  In order to make the L / D of the glass fibers (x) and (y) in the sandwich molded body within such a range, the average fiber length of the glass fibers (x) and (y) in the sandwich molded body is 130 to 600 μm is preferable, and 165 to 700 μm is more preferable. In addition, the fiber diameters of the glass fibers (x) and (y) in the sandwich molded body are equal to the fiber diameters of the glass fibers used as a raw material.

  The sandwich molded body of the present invention is useful for, for example, automobile parts, electrical parts, household goods and the like. Specifically, the parts used in automobiles include cylinder head covers, air intake manifolds, throttle bodies, air intake pipes, radiator tanks, water pump renlets, water pump outlets, thermostat housings, cooling fans, fan shrouds. , Oil pan, oil filter housing, oil filter cap, oil level gauge, timing belt cover, engine cover, door mirror stay, inner mirror stay, roof rail, door mirror bracket, accelerator pedal, brake pedal, clutch pedal, shift lever, gear, seat Suitable for frame, wiper arm, wiper arm link bracket, tonneau cover frame, antenna base, etc.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the raw material used for the Example and the comparative example and the physical property measuring method are as follows.

1 Raw material (A) Polyamide resin [PA-1]: Nylon 6 (A1015 manufactured by Unitika), melting point 220 ° C., melt viscosity 40 Pa · s
[PA-2]: nylon 66 (E2001R manufactured by Unitika), melting point 260 ° C., melt viscosity 40 Pa · s
[PA-3]: Nylon 66 (A125 manufactured by Unitika), melting point 260 ° C., melt viscosity 80 Pa · s
[PA-4]: Nylon 66 (A142 manufactured by Unitika), melting point 260 ° C., melt viscosity 600 Pa · s
[PA-5]: Nylon 66 (ET-1 manufactured by Unitika; test product), melting point 260 ° C., melt viscosity 10 Pa · s
In addition, the said melt viscosity is a value in melting | fusing point +30 degreeC and shear rate 1000s < ^-1 >.

(B) Glass fiber [GF]: CS3H459 manufactured by Nittobo Co., Ltd., glass fiber diameter 10 μm, fiber length 3 mm

(C) Carbon Black [CB-1]: Mitsubishi Chemical Corp. # 4000B, pH 10, oxygen-containing groups concentration of 0.3 wt%, DBP absorption amount 102cmm ³ / 100g, a primary particle diameter 24nm
[CB-2]: Mitsubishi Chemical Corp. # 3030B, pH 6.5, oxygen containing groups concentration of 0.5 wt%, DBP absorption amount 130cmm ³ / 100g, a primary particle diameter 55nm
[CB-3]: Mitsubishi Chemical Corporation # 45, pH 8, oxygen containing groups concentration 1.1 wt%, DBP absorption amount 46cmm ³ / 100g, a primary particle diameter 24nm

(D) Higher fatty acid metal salt [D-1]: Sodium behenate (NS-7 manufactured by Nitto Kasei Kogyo Co., Ltd.)
[D-2]: Calcium montanate (Recommont CaV101 manufactured by Clariant)

2 Measuring method (1) Melt viscosity of polyamide resin composition It evaluated with the measuring method based on JISK7199. The diameter of the orifice was 1 mm, the resin pellets were put in a cylinder heated to the melting point + 30 ° C., preheated for 3 minutes, and then measured at a shear rate of 1000 s ⁻¹ . The melting point of the polyamide resin composition was measured by a differential scanning calorimeter (DSC) according to JIS K7121, and when a plurality of different melting points were detected, the higher melting point was adopted.

(2) Bending strength A
A two-point support bending test was performed at 23 ° C. and a span of 100 mm using a test piece of a sandwiched rod of 127 mm in length, 35 mm in width, and 12 mm in thickness that was sufficiently conditioned in an atmosphere of 50% RH at 23 ° C. Measured. In the test piece of the sandwich molded body, the longitudinal direction was the resin flow direction during molding, and the measurement was performed with the test piece of the sandwich molded body supported at two points in the longitudinal direction. The bending strength A is 300 MPa or more (◯) in a practically unproblematic range, preferably 320 MPa or more, and more preferably 365 MPa or more (（). Less than 300 MPa (x) is a practically problematic range.

(3) Bending strength B
The bending strength B was measured in a high-temperature environment at 100 ° C. in air. Otherwise, the bending test similar to the bending strength A test was performed for measurement. The bending strength B is 200 MPa or more (◯) in a range where there is no practical problem, preferably 210 MPa or more, and more preferably 235 MPa or more (◎). Less than 200 MPa (x) is a practically problematic range.

(4) Volume ratio of skin part (primary material) When molding a test piece of bending strength A, the injection volume of the skin part (primary material) of the sandwich molded body and the core part (secondary material) by an injection molding machine The injection volume of was measured.
The volume ratio of the skin part (primary material) was obtained by adding the injection volume of the primary material measured by the injection molding machine and the injection volume of the secondary material, and calculating the ratio of the injection volume of the primary material to the added total volume. . The injection volume of the primary material and the injection volume of the secondary material were calculated by the product of (screw movement distance during injection molding) and (cylinder cross-sectional area), respectively. The screw movement distance at the time of injection molding was calculated from the difference between (screw position at the completion of metering) and (screw position at the completion of injection). The volume ratio of the skin part is preferably 40 to 70%.

[Preparation and characterization of pellets]
Production Example 1
For the production of the pellet, a same-direction twin screw extruder (TEM37BS manufactured by Toshiba Machine Co., Ltd.) was used. This co-directional twin-screw extruder is equipped with a main hopper for charging the main material and a continuous quantitative supply device (manufactured by Kubota) that supplies the main material to the main hopper at the upstream part, and the auxiliary material is charged in the middle part. Side feeders were provided, and a cooling water tank and a pelletizer were provided downstream.
As the main raw material, the extrusion temperature of the same direction twin screw extruder is set to 270 to 300 ° C., and from the position upstream of the same direction twin screw extruder, from the main hopper to the same direction twin screw extruder by the continuous quantitative supply device. , 45 parts by mass of polyamide resin PA-3, 10 parts by mass of polyamide resin PA-4, and 0.5 parts by mass of carbon black, while the middle position of the same direction twin screw extruder From the side feeder, the glass fiber GF was supplied to 45 parts by mass, and the polyamide resins PA-3 and PA-4 and the glass fiber GF were melt-kneaded at a screw rotation speed of 300 rpm. The blending ratio of the polyamide resins PA-3 and PA-4 and the glass fiber GF was adjusted by the ratio of the feed rate of the main material by the continuous quantitative feeder and the side feed rate of the auxiliary material by the side feeder. Thereafter, a resin composition containing polyamide resins PA-3 and PA-4 and glass fiber GF is taken out in a strand form from a die at a discharge rate of 35 kg / h, cooled and solidified through a cooling water tank, and cut by a pelletizer to form a pellet. Pellets PS-1 having a length of 3 mm were obtained. The resin temperature of the resin composition coming out of the die was 290 ° C. The melt viscosity of the pellet PS-1 was measured at 290 ° C. and 1000 s ⁻¹ and found to be 700 Pa · s. The results are shown in Table 1.

Production Examples 2 to 26
Compared to Production Example 1, the types and blending ratios of the thermoplastic resin and the inorganic filler were changed as shown in Tables 1 and 2. Other than that, pellets were obtained in the same manner as in Production Example 1. The results are shown in Tables 1 and 2.

[Production and physical property evaluation of sandwich moldings]
Example 1
Using a sandwich molding machine (J180AD-2M, manufactured by JSW) that has two primary and secondary cylinders connected by a merge nozzle at the tip, PS-1 is the primary cylinder. PC-1 as a secondary material is injected into the secondary cylinder, and both of them are injected at the same time as the injection of the primary material under the conditions of the cylinder temperature of 300 ° C and the mold temperature of 100 ° C. Under such sequence control, a test piece of a sandwich molded body for measuring physical properties was prepared by injection molding. At this time, injection molding of a test piece (a length of 127 mm, a width of 35 mm, a thickness of 12 mm) of a sandwich molded body for measuring physical properties is performed so that the primary material forms a skin portion and the secondary material forms a core portion. went. And about the test piece of the shape | molded sandwich molded object, various evaluation tests (The test of bending strength A, the test of bending strength B) were done. As a result of separate analysis, the average thickness of the skin part is 1.5 mm, the average thickness of the core part is 9 mm, the volume ratio of the skin part is 60%, and the thickness of the skin part is 25% of the thickness of the sandwich molded body. Accounted for. The results are shown in Table 3.

Examples 2 to 23 / Comparative Examples 1 to 9
The pellets shown in Tables 3 to 5 were used as the primary material (skin part) and the secondary material (core part). And the other than that produced the test piece of the sandwich molded object like Example 1, and performed the same various evaluation tests. The results are shown in Tables 3-5. In addition, Comparative Example 8 was formed only from the primary material, and Comparative Example 9 was formed only from the secondary material.

  In Examples 1 to 23, since a sandwich molded body was produced with the prescription prescribed in the present invention, the bending strength A and the bending strength B under a high temperature environment are both sufficient values, and the strength is excellent even under a high temperature environment. It was possible to obtain a sandwich molded body having

  Since the comparative example 1 had too many glass fibers of the polyamide resin composition (A) in a skin part, the bending strength in normal temperature was low.

  Since the comparative example 2 had too few glass fibers of the polyamide resin composition (A) in a skin part, the bending strength in normal temperature and a high temperature environment was low.

  In Comparative Example 3, since the glass fiber of the polyamide resin composition (B) in the core portion was excessive, the bending strength in a normal temperature and high temperature environment was low.

  Since the comparative example 4 had too few glass fibers of the polyamide resin composition (B) in a core part, the bending strength in a high temperature environment was low.

  Since the ratio of the glass fiber (x) contained in the polyamide resin composition (A) in the skin part and the glass fiber (y) of the polyamide resin composition (B) in the core part was outside the regulation in Comparative Example 5, The bending strength at was low.

  In Comparative Example 6, since the melt viscosity ηa of the polyamide resin composition (A) in the skin portion and the melt viscosity ηb of the polyamide resin composition (B) in the core portion were too small and out of specification, The bending strength at room temperature was low.

  In Comparative Example 7, since the melt viscosity ηa of the polyamide resin composition (A) in the skin portion and the melt viscosity ηb of the polyamide resin composition (B) in the core portion were too large to be specified, The bending strength in a high temperature environment was low.

  Since Comparative Example 8 was formed using only the primary material, the bending strength under a high temperature environment was low.

  Since Comparative Example 9 was formed only from the secondary material, the bending strength under normal temperature and high temperature environment was low.

L: Resin flow direction A: Skin part B: Core part

Claims (4)

A sandwich molded body having a structure in which a skin part is formed on the surface of a core part, the core part being sandwiched by the skin part, and satisfying the following (I) to (IV) simultaneously.
(I) The polyamide resin composition (A) constituting the skin portion contains the polyamide resin (a) and the glass fiber (x), and the mixing ratio (a / x) is 45/55 to 70 by mass ratio. / 30.
(II) The polyamide resin composition (B) constituting the core portion contains the polyamide resin (b) and the glass fiber (y), and the mixing ratio (b / y) is 35/65 to 55 by mass ratio. / 45.
For (III) the polyamide resin composition (A), the melting point + 30 ° C., and a melt viscosity ηa measured at a shear rate of 1000 s ^-1, the polyamide resin composition for (B), the melting point + 30 ° C., measured at a shear rate of 1000 s ^-1 The melt viscosity ηb is
1 <log ηa / log ηb <1.4
It is.
(IV) The content X of the glass fiber (x) contained in the polyamide resin composition (A) and the content Y of the glass fiber (y) contained in the polyamide resin composition (B) are:
X ≦ Y
It is.   The sandwich molded body according to claim 1, wherein the volume ratio of the skin portion is 40 to 70% of the total volume.   The polyamide resin composition (A) further contains 0.1 to 3 parts by mass of carbon black (c) with respect to 100 parts by mass in total of the polyamide resin (a) and the glass fiber (x). The sandwich molded article according to claim 1 or 2.   The polyamide resin composition (B) further contains 0.03 to 3 parts by mass of a higher fatty acid metal salt (d) with respect to 100 parts by mass in total of the polyamide resin (b) and the glass fiber (y). The sandwich molded body according to any one of claims 1 to 3.

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