JP5459005B2 - Press molding method and molded body thereof - Google Patents

Description

  The present invention relates to a press molding method using a molding material composed of reinforcing fibers and a thermoplastic resin, and a molded body obtained by the press molding method, and in particular, a press excellent in moldability for complex shapes and surface appearance. The present invention relates to a molding method.

  In recent years, industrial parts such as automobiles, electrical / electronic equipment, and home appliances that were manufactured by press molding of metal materials have been replaced by molding materials made of reinforcing fibers and thermoplastic resins. ing. This is because a molded body using such a molding material has high strength and is lightweight. Here, press molding is a method of forming, working by applying deformation such as bending, shearing, compression, etc. to various materials exemplified by metals, plastic materials, ceramic materials, etc. using a processing machine, a die, a tool, etc. It is. In addition, press molding is characterized by the ability to produce a large amount of products with relatively uniform accuracy, and there are high demands for high speed, high accuracy, and stable quality for mass production. In order to achieve this, the market demand for improving workability and formability is very high.

  In particular, in a molding method of a molding material using a thermoplastic resin which is a conventional reinforcing fiber and a matrix resin, a mold consisting of a pair of male and female molding materials preheated to a temperature higher than the melting temperature of the thermoplastic resin. Although a press molding method for obtaining a molded product having a desired shape by supplying in between and then pressurizing and cooling is widely known, in the press molding of a fiber reinforced thermoplastic resin molding material, the shape of the mold cavity is obtained. There was a problem related to moldability that the surface appearance of the obtained molded article was wrinkled without shaping.

  In order to improve the surface appearance of the molded body in the press molding described above, a method for uniformly heating the molding material in the preheating step of the molding material composed of reinforcing fibers and a thermoplastic resin has been disclosed. (Patent Document 1). This is because the temperature difference in the thickness direction of the molding material is substantially reduced by controlling the strength of the heating to the molding material by providing a plurality of temperature control zones inside the heating device in the step of preheating the molding material. This is a method of making uniform and then proceeding to press molding. However, the above method has been invented by focusing only on temperature control of the heating device in heating the molding material. Therefore, it has not been stepped into the molding process, which is a subsequent process, and is not a fundamental solution to the market demand for improved moldability.

  Therefore, when a molding material made of a glass fiber reinforced thermoplastic resin is preheated to a sheet material having a different thickness, each of the molding materials can be heated to a predetermined temperature to obtain a molded product having a complicated shape with a low pressure. An intended proposal is disclosed (Patent Document 2). This is because the thickness of the molding material is changed in advance according to the shape of the molded body, and each is heated to the required temperature. It is very difficult to control the temperature of the molding material to be heated, and the moldability is low. It is not a fundamental solution to the market demand for improvement.

JP 63-302007 A JP 61-104814 A

  Accordingly, an object of the present invention relates to a press molding method using a molding material composed of a reinforcing fiber and a thermoplastic resin, and a molded body obtained by the press molding method. It is an object of the present invention to provide a press molding method that is excellent in formability with respect to shape and surface appearance.

(1) In a method for press-molding a molding material composed of reinforcing fibers and a thermoplastic resin, the press-molding method includes the following steps (I) to (IV).
Step (I): After previously laminating the sheet-shaped molding material, when the laminated molding material is heated to a moldable temperature, the temperature is equal to or higher than the plasticizing temperature of the thermoplastic resin constituting the molding material , and The molding material is heated in a heating device until the difference (ta / tb) between the thickness (tb) before heating and the thickness (ta) after heating is 2 to 10 times , and the molding material Heating is performed so that the temperature difference (ΔT = B−A) between the temperature (A) of the outermost layer and the center temperature (B) in the thickness direction of the molding material is within a range of 20 ° C. or more and 100 ° C. or less. Process.
Step (II): A step of conveying the molding material heated to the plasticizing temperature and placing it on the lower mold of the released mold.
Step (III): A step of obtaining a molded product by pressurizing and cooling the molding material by clamping the molding die.
Step (IV): Step of releasing the mold after cooling and taking out the molded product from the mold.

( 2 ) The press molding method according to (1 ), wherein in the step (I), the thickness of the molding material before the molding material is heated is in the range of 1 to 10 mm.

( 3 ) The press molding method according to (1) or (2) , wherein the pressure applied to the projected area of the molded product is in the range of 10 to 50 MPa in the step (III).

( 4 ) The steps (III) to (IV) are performed within a temperature range in which the temperature of the mold is 20 ° C. to 100 ° C. lower than the solidification temperature of the thermoplastic resin constituting the molding material. ( 3 ) The press molding method according to any one of the above.

( 5 ) The press molding method according to any one of (1) to ( 4 ), wherein the molding material comprises the following component (a) and component (b).
Component (a): Reinforcing fiber: 25-80% by mass
Component (b): at least one thermoplastic selected from the group consisting of polycarbonate resin, styrene resin, polyamide resin, polyester resin, polyphenylene sulfide resin, modified polyphenylene ether resin, polyetherimide resin, polyolefin resin and polyacetal resin Resin: 20-75% by mass.

( 6 ) The press molding method according to ( 5 ), wherein the mass average fiber length of the component (a) is in the range of 1 to 50 mm.

( 7 ) The press molding method according to ( 5 ) or ( 6 ), wherein the component (a) is at least one selected from carbon fiber, glass fiber, aramid fiber, and mineral fiber.

( 8 ) The press molding method according to any one of ( 5 ) to ( 7 ), wherein the component (b) is at least one selected from polyolefin resins, polyamide resins, polyester resins, and polyetherimide resins. .

( 9 ) A molded article obtained by the press molding method according to any one of (1) to ( 8 ), which is a part / member used for automobiles, electrical / electronic devices, household electrical appliances, or aircraft.
It is.

  The press molding method using the molding material comprising the reinforcing fiber and the thermoplastic resin of the present invention improves the formability of the molding material with respect to the molding die having a complex shape, and further, the molded body obtained by the press molding method. Is excellent in surface appearance. For this reason, it is extremely useful for parts / members used in automobiles, electrical / electronic devices, household electrical appliances, or aircraft applications.

It is the simplified diagram which showed one Example of the heating profile of the molding material. It is the simplified diagram which showed one embodiment of the molding material arrange | positioned in a heating apparatus and a state change. It is the simplified diagram which showed one embodiment of the molding material arrange | positioned in a heating apparatus and a state change. It is the simple figure which showed the temperature measurement location of the molding material heated from the thickness direction. It is the simple figure which showed the temperature measurement location of the molding material heated from the plane part. It is a simplified diagram which shows the positional relationship of a heating apparatus and a shaping | molding die used for the Example and the comparative example. In one Example of press molding, it is the simple figure which showed the aspect by which the molding material is arrange | positioned. In one Example of press molding, it is the simple figure which showed the aspect from which the shape of a molding material changes. In one Example of press molding, it is the simple figure which showed the aspect by which the molding material was shaped. It is a simplification figure of one Example of the molded object obtained by the press molding method of this invention. It is a simplification figure of one comparative example of the molded object obtained by the press molding method. It is the simplification figure which showed the cavity of the shaping | molding die from the opening-and-closing direction of the press apparatus.

  Hereinafter, preferred embodiments of the present invention will be described.

  The present invention is a press molding method comprising the following steps (I) to (IV) in a method of press molding a molding material comprising reinforcing fibers and a thermoplastic resin.

  Steps (I) to (IV) are described below, and a series of operations performed in steps (I) to (IV) are shown in FIGS. 6-a, 6-b, and 6-c.

  In the step (I), a sheet-shaped molding material is laminated in advance, and then heated to a temperature equal to or higher than the plasticizing temperature of the thermoplastic resin constituting the molding material, and the temperature (A) of the outermost layer of the molding material And a temperature difference (ΔT = B−A) of the center temperature (B) in the thickness direction of the molding material is heated to a temperature in the range of 20 ° C. or more and 100 ° C. or less (FIG. 1). . Since it is necessary to heat the laminated molding material to a plasticizing temperature or higher that can be molded, it is heated using a heating device exemplified by a far-infrared heater, a heating plate, a high-temperature oven, dielectric heating, etc. A melted and softened state (plasticization) can be obtained, and among them, a far infrared heater can be preferably used because of easy control of the heating state. FIG. 2 shows a simplified diagram of a molding material heated by a far infrared heater. Furthermore, FIG. 5 shows the positional relationship between a heating device and a molding die installed in a press device (not shown). The heating device is disposed in the vicinity of the molding die installed in the press device, and is disposed so that the heated molding material can be immediately conveyed into the molding die. In order to prevent cooling before molding, and from the viewpoint of workability, the arrangement layout can be changed as appropriate. However, from the above viewpoint, it is preferably installed in the vicinity of the mold.

  Next, the raw materials used for the sheet-shaped molding material will be described. Reinforcing fibers (component (a)) constituting the molding material used in the press molding method of the present invention, the molded body has a high strength of the molded body in order to meet demands such as weight reduction of its members, High rigidity is strongly desired. For this reason, fibers having high strength and elastic modulus are often used as reinforcing fibers, and the fiber length tends to be as long as possible. In addition, from the viewpoint of the freedom of the form of the thermoplastic resin, which is the component (b) constituting the sheet-shaped molding material, and the economics of the production method, it is often used after being processed into a nonwoven fabric by a papermaking method or the like. . A sheet-like molding material is obtained by impregnating the reinforcing fiber processed into the nonwoven fabric form with a thermoplastic resin (component (b)) in the form of a film, powder or fiber.

  In the molding material having such a form, the thermoplastic resin is melted by heating in the step (I) described later, so that the reinforcing fibers that have been restrained by the thermoplastic resin are released. As a result, the reinforcing fibers pressed down by the thermoplastic resin are elastically recovered, and the apparent thickness of the molding material increases. This increase in thickness is called a springback and tends to increase as the fiber length increases and as the tensile elastic modulus of the reinforcing fiber increases.

  In other words, this spring back represents an increase in the amount of voids in the molding material, and in the heating process, the surface of the molding material (outermost layer) is preferentially heated, so the thickness direction of the molding material The center of is apparently insulative. Thus, although the surface is difficult to be heated above a certain temperature due to the balance with the atmosphere, the central portion in the thickness direction continues to rise in proportion to the amount of energy applied. When the molding material is heated under high energy for a long time, it becomes higher than the decomposition temperature of the thermoplastic resin, so that the moldability is inferior. On the other hand, since the melt viscosity of the thermoplastic resin is lowered, the formation of the molding die tends to be improved.

  Therefore, in step (I), the temperature (A) (4) of the outermost layer shown in FIGS. 4-a and 4-b of the molding material and the temperature (B) ( It is essential that the temperature difference (ΔT = B−A) in 5) is heated to a temperature in the range of 20 ° C. or more and 100 ° C. or less. The temperature difference (ΔT = B−A) needs to be a temperature at which the central temperature (B) in the thickness direction of the molding material exceeds the temperature (A) of the outermost layer, as shown in FIG. By setting (ΔT) to be 20 ° C. or more and 100 ° C. or less, the heated molding material is affected by heat exchange with the mold and the ambient temperature in the heating apparatus, and the process (II) and the process (III In any case, the problem that the thermoplastic resin constituting the molding material is solidified prior to molding and cannot be molded into the desired shape can be solved.

  That is, since the surface of the molding material first comes into contact with the mold, the molding material is preferentially solidified at a high speed due to heat exchange with the mold, making it difficult to flow and deform the molding material. . In other words, if ΔT is not included in such a range, the molding material will be inferior in shape. Therefore, by maintaining ΔT within this range, this fluid and deformable state can be maintained. This is a point for improving the formability.

  On the other hand, among the press molding methods, for molding materials composed of reinforcing fibers and thermoplastic resins, the mold press method is used to raise the temperature of the molding die to a temperature equal to or higher than the plasticizing temperature of the thermoplastic resin in advance. The molding material is placed in the formed mold, pressed by clamping, and then the mold is cooled while maintaining the state, or the molding material is placed in the mold in advance, There is a so-called hot press method in which pressurization and heating are performed together with mold clamping, and then the molding material is cooled by cooling the mold while the mold is clamped. According to this hot pressing method, it is widely known that the shapeability and surface appearance of a molded product are excellent, and it can be said to be an ideal molding method. However, for example, in order to mold a molding material using a polyamide-based resin by a hot press method, after the molding die is heated to 230 to 280 ° C., the molding material is placed in the molding die, and the mold is clamped. After the molding is completed, the mold must be cooled to 160 ° C. or lower, so that the advantages over the present invention are not achieved in terms of production speed and production cycle.

  Here, the plasticizing temperature of the thermoplastic resin constituting the molding material can be determined by DSC (Differential Scanning Calibration). The measurement is performed at a temperature rising rate of 10 ° C./min, and the peak top of the melting peak in the obtained DSC curve is defined as the plasticization temperature.

  Step (II) is a step of conveying the molding material heated to the plasticizing temperature and placing it on the lower mold of the released molding die. Step (II) is a step of conveying the molding material heated to the plasticizing temperature and placing it in the released mold. The heated molding material is conveyed manually or by a robot and placed in the released mold. When transporting, a manpower or a robot is appropriately selected from the viewpoint of work safety and placement accuracy of a molding material on a molding die in which press molding is performed.

  Step (III) is a step of obtaining a molded product by pressure-cooling the molding material by clamping the molding die. Step (III) is a step of pressurizing and cooling the molding material heated to the plasticizing temperature by clamping the mold. In the step of pressure cooling, press molding is used, and the type can be selected according to the obtained molded body. Here, press molding is a method of obtaining a molded body by applying deformations such as bending, shearing, and compression to various materials exemplified by metals, plastic materials, ceramic materials, etc. using a processing machine, a mold, a tool, and the like. However, examples of the forming form include drawing, deep drawing, flange, call gate, edge curling, and stamping. Examples of the press molding method include a mold pressing method in which molding is performed using a mold, a rubber press method (hydrostatic pressure molding method), and the like. Among the above press molding methods, a mold press method in which molding is performed using a metal mold can be preferably used from the viewpoint of flexibility in molding pressure and temperature.

  Step (IV) is a step of releasing the mold after cooling and taking out the molded product from the mold.

In the present invention, when the molding material is heated in the step (I), the difference between the thickness (tb) of the molding material before heating (illustrated in FIG. 2) and the thickness after heating (ta) (illustrated in FIG. 2) By including the step of heating in the heating device until (ta / tb) becomes 2 to 10 times, the effect of the present invention can be maximally utilized by the above-described control of the spring back, and the shapeability and It is required from the viewpoint of improving the surface appearance of the molded body. In particular, it is preferable that (ta / tb) is in the range of 2 to 5 times since the transporting step, which is the later step (II), becomes simple.

  In the step (I), it is preferable that the thickness of the molding material before the molding material is heated is in the range of 1 to 10 mm because the heating time can be shortened. Especially preferably, it exists in the range of 1-5 mm from stability of a heating state, and the balance of process time.

  In the step (II), as shown in FIG. 3, two pairs of molding materials having a thickness exceeding 50% of the thickness of the molded body obtained in the step (III) can be transferred simultaneously from the heating device to the mold. This is preferable from the viewpoints of workability and economical efficiency because the carrying work can be simplified and the ability of the carrying device can be minimized.

  In the step (III), it is easy to form a molding material that is plasticized so that the pressure applied to the projected area of the cavity of the concave portion of the molding die forming the molded product is within a range of 10 to 50 MPa, molding This is preferable from the viewpoint of ease of body thickness control. In particular, the range of 15 MPa to 30 MPa is preferable from the viewpoint of the equipment cost of the press molding machine. Here, the projected area of the cavity of the concave portion of the mold (a) is a two-dimensional flat area viewed from the opening and closing direction of the mold as shown in 8 of FIG. When it has, it becomes smaller than the development area of an actual molded product.

  In the steps (III) to (IV), the plasticizing molding material should be applied in such a manner that the temperature of the molding die is 20 ° C. to 100 ° C. lower than the solidification temperature of the thermoplastic resin constituting the molding material. It is preferable from the viewpoint of ease of shape and surface appearance of the molded body. For example, when a polyamide 6 resin is used as the matrix resin (component (B)), a preferable range is within the range of 120 ° C. to 160 ° C., and when a polypropylene resin is used, a preferable range is within the range of 80 ° C. to 120 ° C.

  Further, the press molding method of the present invention can simplify the molding operation when the step of operating the ejector is included between the steps (III) and (IV) for the purpose of assisting the step (IV). It is preferable in that it can prevent troubles in forming and molding. In addition, the ejector can be preferably used by either a method of blowing compressed air or a method of pushing up by a mechanical structural member.

  The molding material composed of the reinforcing fiber and the thermoplastic resin is not particularly limited as long as it is a thermoplastic resin reinforced with the reinforcing fiber. For example, a plurality of strand-shaped reinforcing fibers are pierced with a needle and the fibers are entangled with each other. Laminated mat-like strand reinforced fiber is laminated with a thermoplastic resin, molding material obtained by heating and pressurizing this, molten thermoplastic resin is attached to the reinforcing fiber bundle, molding material obtained by pressing, only reinforcing fiber, Or the molding material obtained by disperse | distributing the thermoplastic resin of a powder form and a fiber form, and heating and pressing this. Reinforced fibers, powdered and fiber-shaped thermoplastic resin are dispersed in water, and a non-woven material obtained by making a paper from a mixed suspension is heated and pressed to form a molding material. Only reinforcing fibers are dispersed in water. A nonwoven material obtained by paper-making from a suspension is heated and pressed with a thermoplastic resin in the form of powder, fiber, film or nonwoven fabric, and the heat is applied to the nonwoven material of the reinforcing fiber obtained by paper-making. A known molding material such as a molding material formed by adhering a plastic resin can be used. Among these, a molding material obtained by adhering the thermoplastic resin to the nonwoven material of the reinforcing fiber is preferable from the viewpoints of dispersibility of the reinforcing fiber and freedom of the form of the thermoplastic resin, and economics of the manufacturing method. Can be used.

  The component (a) is preferably at least one selected from carbon fiber, glass fiber, aramid fiber, and mineral fiber, which can be expected to have a great reinforcing effect by the reinforcing fiber. The fiber is more preferable because a high reinforcing effect can be obtained, and carbon fiber having a large reinforcing effect on the thermoplastic resin by the reinforcing fiber is particularly preferable.

  Furthermore, it is preferable that this component (a) is contained in the ratio of 25-80 mass%. In view of the mechanical properties of the molded article obtained by the present invention, it is more preferably contained in a proportion of 30 to 75 mass%, particularly preferably 35 to 70 mass%. When the mass content of the carbon fiber is 25% by mass or more, the reinforcing effect of the reinforcing fiber of the molded body obtained by the press molding method of the present invention is exhibited, so that the bending strength required when used as a structural member is obtained. Can demonstrate. Moreover, when the mass content of the carbon fiber is 80% by mass or less, the impregnation of the thermoplastic resin between the reinforcing fiber and the thermoplastic resin can be satisfied, and the moldability can be secured.

  Furthermore, it is preferable that the mass average fiber length of the said component (a) is 1-50 mm. The mass average fiber length of the reinforcing fibers is more preferably 1.5 to 26 mm, and further preferably 2 to 6.5 mm. When the mass average fiber length of the reinforcing fiber is longer than 1 mm, the fiber reinforcing effect is large, which is suitable for use as a structural member. Further, when the mass average fiber length of the reinforcing fibers is shorter than 50 mm, the steric hindrance due to the entanglement of the reinforcing fibers can be reduced, so that the occurrence of defects in the molded body obtained by the press molding method of the present invention can be suppressed. This is preferable because it is possible. The average fiber diameter of the reinforcing fibers is not particularly limited, but is preferably in the range of 1 to 20 μm and in the range of 3 to 15 μm from the viewpoint of mechanical properties and surface appearance of the obtained molded product. More preferred.

  The reinforcing fiber may be included as a reinforcing fiber bundle in which single yarns of a plurality of reinforcing fibers are combined. In this case, the number of single yarns of the reinforcing fiber bundle is not particularly limited, and can be used within the range of 100 to 350,000, and particularly within the range of 1,000 to 250,000. preferable. Further, from the viewpoint of productivity of reinforcing fibers, those having a large number of single yarns are preferable, and it is preferable to use them within a range of 20,000 to 100,000. When reinforcing fibers are included as reinforcing fiber bundles, a composition such as urethane resin, polyamide resin, epoxy resin, acrylic resin, etc., is given as appropriate in order to give the reinforcing fiber bundle a converging property and improve handling. It may be what you did. Furthermore, in order to make dispersion | distribution of a reinforced fiber favorable in a fiber reinforced thermoplastic resin composition, you may use what cut the reinforced fiber bundle. In addition, the reinforcing fiber is preferably in the form of a web or mat-like sheet in which reinforcing fibers are randomly oriented from the viewpoint of obtaining a mechanically isotropic fiber.

  The component (b) includes, for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, and liquid crystal polyester, polyolefins such as polyethylene, polypropylene, and polybutylene, polyoxymethylene, polyamide, Fluorine resins such as polyphenylene sulfide, polyketone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyethernitrile, polytetrafluoroethylene, crystalline resins such as liquid crystal polymer, styrene resin, polycarbonate, Polymethyl methacrylate, polyvinyl chloride, polyphenylene ether, polyimide, polyamideimide, polyetherimide, polysulfone, polyether Amorphous resins such as rusulphone, polyarylate, phenolic resin, phenoxy resin, polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, fluorine, acrylonitrile, etc. And thermoplastic resins selected from these copolymers and modified products. In the present invention, at least one of these can be employed as the thermoplastic resin. Preferably, from the economical viewpoint, the component (b) is a polycarbonate resin, a styrene resin, a polyamide resin, a polyester resin, a polyphenylene sulfide resin, a modified polyphenylene ether resin, a polyetherimide resin, a polyolefin resin, or a polyacetal resin. It is at least one thermoplastic resin selected from the group, and more preferably at least one selected from polyolefin resins, polyamide resins, polyester resins, and polyetherimide resins. This is from the viewpoint of moldability in which a thermoplastic resin is impregnated between the reinforcing fibers.

  Furthermore, it is preferable that the compounding quantity of the said component (b) is a ratio of 20-75 mass%. Like the viewpoint of the content of the reinforcing fiber, it is more preferably contained in a proportion of 25 to 70 mass%, particularly preferably 30 to 65 mass%.

  In addition, the component (b) can include a mixture of the above-described thermoplastic resins or a polymer alloy using these thermoplastic resins and a modified product thereof, if necessary. Includes all of these. Such thermoplastic resins may optionally contain various compounding agents that are usually compounded, such as stabilizers, pigments, and fillers.

  The molded body obtained by the press molding method of the present invention can be developed for various uses. Parts for automobiles and motorcycles such as various modules such as instrument panels, door beams, under covers, lamp housings, pedal housings, radiator supports, spare tire covers, front ends, notebook computers, mobile phones, digital still cameras, PDAs, plasmas Electrical and electronic parts such as displays, telephones, facsimiles, VTRs, photocopiers, televisions, microwave ovens, audio equipment, toiletries, laser discs, refrigerators, air conditioners and other household and office electrical parts, civil engineering and construction parts, aircraft It can be used for various applications such as automotive parts, and is particularly preferably used for electronic equipment parts and automobile parts.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the raw material used for the Example is as follows.

(Reference Example 1)
Component (a) Reinforcing fiber (PAN-based carbon fiber)
The PAN-based carbon fiber that is a reinforcing fiber was produced as follows.

Using a copolymer composed of 99.4 mol% of acrylonitrile (AN) and 0.6 mol% of methacrylic acid, an acrylic fiber bundle having a single fiber denier 1d and a filament number of 24,000 was obtained by a dry and wet spinning method. The obtained acrylic fiber bundle is heated at a draw ratio of 1.05 in air at a temperature of 240 to 280 ° C., converted to flame-resistant fiber, and then heated in a temperature range of 300 to 900 ° C. in a nitrogen atmosphere. After 10% stretching at a rate of 200 ° C./min, the temperature was raised to a temperature of 1,300 ° C. and fired. This carbon fiber bundle was subjected to an electrolytic surface treatment of 3 coulombs per gram of carbon fiber with an aqueous solution containing sulfuric acid as an electrolyte, and dried in heated air at a temperature of 120 ° C. to obtain a PAN-based carbon fiber bundle.
Total number of filaments: 24,000 Single fiber diameter: 7 μm
Mass per unit length: 0.8 g / m
Specific gravity: 1.8 g / cm ³
Tensile strength (Note 1): 4.2 GPa
Tensile modulus (Note 2): 230 GPa.

(Note 1) Tensile strength, (Note 2) Tensile modulus measurement conditions It was determined by the technique described in Japanese Industrial Standard (JIS) -R-7601 “Resin Impregnated Strand Test Method”. However, the resin-impregnated strand of carbon fiber to be measured is impregnated with “BAKELITE” (registered trademark) ERL 4221 (100 parts by mass) / 3 boron fluoride monoethylamine (3 parts by mass) / acetone (4 parts by mass). And cured at 130 ° C. for 30 minutes. The number of strands measured was 6, and the average value of each measurement result was the tensile strength and tensile modulus of the carbon fiber.

(Reference Example 2)
As the component (b-1) thermoplastic resin, polyamide 6 resin (manufactured by Toray Industries, Inc., “Amilan (registered trademark)” CM1001, specific gravity: 1.13, plasticization temperature: 225 ° C.) was used.

  Use a Teflon (registered trademark) sheet (thickness 1 mm) as a release sheet between the hot platen surfaces of a hydraulic press machine composed of upper and lower hot platen surfaces heated to 240 ° C., and sandwich the polyamide 6 resin. Arranged. Polyamide 6 resin was added and arranged so that there was no bias. Then, it was pressed at 3 MPa. Next, it is placed between the cooling plates of a hydraulic press machine composed of upper and lower hot plate surfaces controlled to a temperature of 30 ° C., cooled at 3 MPa, and has a length of 1000 mm, a width of 1000 mm, and a thickness of 0.1 mm. A polyamide film (hereinafter abbreviated as PA) was obtained.

(Reference Example 3)
As the component (b-2) thermoplastic resin, an unmodified polypropylene resin (manufactured by Prime Polymer Co., Ltd., “Prime Polypro (registered trademark)” J105G, specific gravity: 0.91, plasticizing temperature: 160 ° C.) was used.

  Use a Teflon (registered trademark) sheet (thickness 1 mm) as a release sheet between the hot platen surfaces of a hydraulic press machine composed of upper and lower hot platen surfaces heated to 200 ° C., and sandwich polypropylene resin between them. Arranged. Polypropylene resin was added and arranged so that there was no bias. Then, it was pressed at 3 MPa. Next, it is placed between cooling plates of a hydraulic press machine composed of upper and lower hot plate surfaces controlled to a temperature of 30 ° C., and is cooled and pressed at 3 MPa, and has a length of 1000 mm, a width of 1000 mm, and a thickness of 0.13 mm. Of polypropylene film (hereinafter abbreviated as PP).

(Reference Example 4)
As a component (a), the carbon fiber continuous bundle obtained in Reference Example 1 was cut with a cartridge cutter to obtain a chopped yarn having a fiber length of 6.4 mm. Surfactant (manufactured by Wako Pure Chemical Industries, Ltd., “Sodium n-dodecylbenzenesulfonate” (product name), 100 liters of a 1.5 wt% aqueous solution was stirred to prepare a pre-foamed dispersion. 100 g of the chopped yarn obtained was put into the liquid, stirred for 10 minutes, then poured into a paper machine having a paper surface of 1000 mm length × width 1000 mm, dehydrated by suction, and then at a temperature of 150 ° C. for 2 hours. It dried and obtained the nonwoven fabric (henceforth CF) which consists of carbon fibers.

(Reference Example 5)
One non-woven fabric made of carbon fiber obtained in Reference Example 4 and one sheet of PA obtained in Reference Example 2 are sandwiched between both sides of the non-woven fabric made of carbon fiber, and the sheet has a configuration of [PA / CF / PA]. It was. Further, a Teflon (registered trademark) sheet (thickness: 1 mm) was used as the release sheet, and the sheet was disposed so as to be sandwiched. Subsequently, it arrange | positioned between the hot platen surfaces of the hydraulic press machine comprised from the upper and lower hot platen surface heated to the temperature of 240 degreeC, and pressed at 5 MPa. Next, it was placed between cooling plates controlled at a temperature of 30 ° C. and cooled and pressed at 5 MPa to obtain a molding material composed of reinforcing fibers having a length of 1000 mm, a width of 1000 mm, and a thickness of 0.26 mm and a thermoplastic resin. .

(Reference Example 6)
One non-woven fabric made of carbon fiber obtained in Reference Example 4 was sandwiched between both sides of the non-woven fabric made of carbon fiber and PP obtained in Reference Example 3 to obtain a sheet having a structure of [PP / CF / PP]. Further, a Teflon (registered trademark) sheet (thickness: 1 mm) was used as the release sheet, and the sheet was disposed so as to be sandwiched. Subsequently, it arrange | positioned between the hot platen surfaces of the hydraulic press machine comprised from the upper and lower hot platen surface heated to the temperature of 200 degreeC, and pressed at 5 MPa. Next, it was placed between cooling plates controlled at a temperature of 30 ° C. and cooled and pressed at 5 MPa to obtain a molding material composed of reinforcing fibers and a thermoplastic resin having a length of 1000 mm, a width of 1000 mm, and a thickness of 0.31 mm. .

(Reference Example 7)
In the step (I), the temperature of the molding material was measured under the following conditions.

  4-a and 4-b, the center point 4 of the molding material was the outermost layer A, and the center point 5 in the thickness direction of the molding material was the center layer B in the thickness direction. The measurement was performed at 1 second intervals using a K-type thermocouple and a Keyence data logger “NR600”. The K thermocouple was sandwiched between molding materials and carefully placed in a heating device so as not to be displaced during temperature measurement.

(Reference Example 8)
The apparent thickness change of the molding material in step (I) was measured as follows.

  The thickness of the molding material before heating was measured with a micrometer to obtain (tb). Further, the molding material after heating was taken out and sufficiently cooled at room temperature and no load, and then the thickness was measured with a micrometer (ta). The multiple of the apparent change in thickness was the left equation (ta / tb).

  Here, the evaluation criteria of the molded bodies obtained by Examples and Comparative Examples are described below.

(Evaluation 1) Evaluation of surface appearance The molded body obtained by the press molding method was visually observed and judged according to the following criteria.
A: The surface appearance of the molded article is excellent with no fading or swelling.
B: Although there is no practical problem, a faint trace is observed on the surface.
C: It is inferior because of faintness and swelling.

(Evaluation 2) Evaluation of shape moldability The molded body obtained by the press molding method was visually observed and judged according to the following criteria.
A: The surface appearance of the molded body is excellent with no standing walls, deep drawing, unfilled portions of the overhanging portions, and perforated portions.
B: Although there is no problem in practical use, a faint trace can be seen on the standing wall, deep drawing, and overhang.
C: Inferior because there are unfilled or perforated standing walls, deep drawing and overhangs

  In any evaluation, A and B were acceptable and C was not.

Example 1
Using the component (a) for the reinforcing fiber and the component (b-1) for the thermoplastic resin, the sheet-like molding material obtained in the manner described in Reference Example 5 is laminated so as to satisfy the conditions described in Table 1. It was adjusted. The mold shown in FIG. 5 was used. Also, the mold temperature was adjusted to 6 and 7 in FIG. 5 using oil at 150 ° C. Thereafter, the molding material was placed in two pairs in an oven equipped with a far infrared heater (FIG. 3), held for 500 seconds, and preheated. The temperature of each point in the molding material at that time was measured in the manner described in Reference Example 7. Subsequently, the molding material was arranged so that the molding material of the molding material was accommodated on the projection surface of the concave portion of the mold cavity surface (FIG. 6A). Thereafter, the convex mold was immediately lowered at a speed of 20 mm / second, and the mold was filled in the cavity (FIG. 6B), and the mold was clamped until the bottom thickness of the cavity became 1.5 mm. Thereafter, pressurization and cooling were performed for 50 seconds so as to maintain this state (FIG. 6C), and then the molding die was opened to remove the surplus portion and obtain a molded body (FIG. 7). The evaluation conditions and results are summarized in Table 1.

(Example 2)
The molding material was preheated by holding for 450 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 1.

(Example 3)
The molding material was preheated by holding for 400 seconds in an oven equipped with a far infrared heater. The temperatures at each point of the molding material at that time are summarized in Table 1. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 1.

Example 4
The molding material was preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 1.

(Example 5)
The molding material was preheated by holding for 300 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 1.

(Comparative Example 1)
The molding material was held in an oven equipped with a far-infrared heater for 300 seconds, and the temperature of the outermost layer was cooled by air blowing, and the temperature was adjusted as shown in Table 1. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 1.

(Example 6)
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 2.

(Example 7)
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. The temperatures at each point of the molding material at that time are summarized in Table 2. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 2.

(Example 8)
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 2.

Example 9
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 2.

(Example 10)
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 3.

(Example 11)
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 3.

(Example 12)
The number of molding material layers and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 3.

(Example 13)
The blending amounts of component (a) and component (b) constituting the molding material, and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 4.

(Example 14)
The blending amounts of component (a) and component (b) constituting the molding material, and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 4.

(Example 15)
The blending amounts of component (a) and component (b) constituting the molding material, and the molding material were preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 1. The evaluation conditions and results are summarized in Table 4.

(Example 16)
Using the component (a) for the reinforcing fiber and the component (b-2) for the thermoplastic resin, the sheet-like molding material obtained in the manner described in Reference Example 6 is laminated so as to satisfy the conditions described in Table 1. It was adjusted. The mold shown in FIG. 5 was used. The mold temperature was adjusted to 130 ° C. using oil. Thereafter, the molding material was placed in an oven equipped with a far-infrared heater in two pairs (FIG. 3), held for 500 seconds, and preheated. The temperatures at each point of the molding material at that time are summarized in Table 5. Next, the molding material was arranged so that the molding material was accommodated in the concave portion of the mold cavity surface (FIG. 6A). Thereafter, the convex mold was immediately lowered at a speed of 20 mm / second, and the mold was filled in the cavity (FIG. 6B), and the mold was clamped until the bottom thickness of the cavity became 1.5 mm. Thereafter, pressurization and cooling were carried out for 50 seconds so as to maintain this state (FIG. 6C), and then the mold was opened to remove the surplus portion and obtain a molded body. The evaluation conditions and results are summarized in Table 5.

(Example 17)
The molding material was preheated by holding for 450 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 16. The evaluation conditions and results are summarized in Table 5.

(Example 18)
The molding material was preheated by holding for 400 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 16. The evaluation conditions and results are summarized in Table 5.

(Example 19)
The molding material was preheated by holding for 350 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 16. The evaluation conditions and results are summarized in Table 5.

(Example 20)
The molding material was preheated by holding for 300 seconds in an oven equipped with a far infrared heater. Otherwise, a molded body was obtained in the same manner as in Example 16. The evaluation conditions and results are summarized in Table 5.

(Comparative Example 2 )
The molding material was held in an oven equipped with a far-infrared heater for 300 seconds, and the temperature of the outermost layer was cooled by air blowing, and the temperature was adjusted as shown in Table 5. Otherwise, a molded body was obtained in the same manner as in Example 16. The evaluation conditions and results are summarized in Table 5.

  As mentioned above, in Examples 1-20, the press molding method which was excellent in both the shape moldability and surface appearance as shown in FIG. 7 was able to be obtained. Moreover, the press of Examples 13-15 which changed the compounding quantity of Examples 6-8, 10-12, 14, 15, component (a) and component (b) which changed the number of lamination | stacking within the scope of the present invention Also in the molding method, a molded article having excellent surface appearance and shape shaping property could be obtained, and good results were obtained.

On the other hand, in Comparative Examples 1 and 2 , as shown in FIG. 8, the side surface was blurred and the appearance of the surface was deteriorated due to distortion. Moreover, the shape shaping property that the desired shape due to insufficient filling could not be obtained was inferior .

A Temperature of outermost layer of molding material B Center temperature of molding material in thickness direction ΔT B / A temperature difference 1 Stacked molding material 2 Stacked and expanded molding material 3 Distant provided in heating device Infrared heater ta Simplified diagram showing the thickness of the molding material (thickness before heating) immediately after being put into the heating device tb Simplified diagram showing the thickness of the molding material (thickness after heating) that was put into the heating device and completed heating 4 Measurement points for the temperature of the outermost layer in the molding material 5 Measurement points for the center temperature in the thickness direction of the molding material 6 Mold used in the example (upper mold)
7 Mold used in the examples (lower mold)
8 Cavity portion of the mold used in the examples 9 Heated molding material arranged in the mold 10 Cross section of the molded body obtained by the example 11 Side surface of the molded body obtained by the example 12 Obtained by the example Molded body 13 Defective part (distortion) in the cross section of the molded body obtained by the comparative example
14 Defective part (fading) on the side surface of the molded product obtained by the comparative example
15 Molded body obtained by Comparative Example

Claims (9)

A press molding method comprising the following steps (I) to (IV) in a method of press molding a molding material comprising a reinforcing fiber and a thermoplastic resin.
Step (I): After previously laminating the sheet-shaped molding material, when the laminated molding material is heated to a moldable temperature, the temperature is equal to or higher than the plasticizing temperature of the thermoplastic resin constituting the molding material , and The molding material is heated in a heating device until the difference (ta / tb) between the thickness (tb) before heating and the thickness (ta) after heating is 2 to 10 times , and the molding material Heating is performed so that the temperature difference (ΔT = B−A) between the temperature (A) of the outermost layer and the center temperature (B) in the thickness direction of the molding material is within a range of 20 ° C. or more and 100 ° C. or less. Process.
Step (II): A step of conveying the molding material heated to the plasticizing temperature and placing it on the lower mold of the released mold.
Step (III): A step of obtaining a molded product by pressurizing and cooling the molding material by clamping the molding die.
Step (IV): Step of releasing the mold after cooling and taking out the molded product from the mold . The press molding method according to claim 1, wherein in the step (I), the thickness of the molding material before the molding material is heated is in the range of 1 to 10 mm. The press molding method according to claim 1 or 2 , wherein, in the step (III), a pressure applied to a projected area of the molded product is within a range of 10 to 50 MPa. Wherein step (III) ~ (IV) is, the temperature of the mold than the solidification temperature of the thermoplastic resin constituting the molding material is effected within the range of 20 ° C. to 100 ° C. lower temperatures, more of claims 1 to 3 A press molding method according to claim 1. The press molding method according to any one of claims 1 to 4 , wherein the molding material comprises the following component (a) and component (b).
Component (a): Reinforcing fiber: 25-80% by mass
Component (b): at least one thermoplastic selected from the group consisting of polycarbonate resin, styrene resin, polyamide resin, polyester resin, polyphenylene sulfide resin, modified polyphenylene ether resin, polyetherimide resin, polyolefin resin and polyacetal resin Resin: 20 to 75% by mass The press molding method according to claim 5 , wherein the mass average fiber length of the component (a) is in the range of 1 to 50 mm. The press molding method according to claim 5 or 6 , wherein the component (a) is at least one selected from carbon fiber, glass fiber, aramid fiber, and mineral fiber. The press molding method according to any one of claims 5 to 7 , wherein the component (b) is at least one selected from polyolefin resins, polyamide resins, polyester resins, and polyetherimide resins. The molded object obtained by the press molding method in any one of Claims 1-8 which are the components and members used for the use of a motor vehicle, an electrical / electronic device, a household appliance, or an aircraft.

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