JP2015051630A - Method for producing laminate substrate and laminate substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably producing a laminate substrate which has low variation in dynamic characteristics and excellent shapability into a complicated shape and can be formed in a short time while maintaining excellent dynamic characteristics such as flexural strength or tensile elasticity applicable to a structural material and to provide a laminate substrate.SOLUTION: There is provided a method for producing a laminate substrate in which two or more prepregs containing a reinforced fiber and a thermoplastic resin are laminated and the laminate is heated at a boiling point of the thermoplastic resin or the glass transition temperature or more while pressurizing the laminate by sandwiching between plates to heat and then integrated by cooling at the boiling point of the thermoplastic resin or the glass transition temperature or less while pressurizing at a pressure during heating or more, wherein the ratio between the area of the laminate substrate after the integration and the area of the laminate substrate before the integration is 1.01 to 1.10.

Description

  The present invention is excellent in shaping into a complicated shape at the time of stamping molding, can be molded in a short time, and has excellent mechanical properties and low variability in which the molded part can be applied to a structural material And a manufacturing method thereof. More specifically, an intermediate base of fiber reinforced plastic that easily follows the molding of three-dimensional shapes such as ribs and bosses, maintains mechanical strength as a structural member, and is suitably used for, for example, aircraft members, automobile members, sports equipment, and the like. The present invention relates to a method for producing a laminated base material and a laminated base material.

  As a method for molding fiber-reinforced thermoplastics, stamping is performed by laminating a base material impregnated with a thermoplastic resin into continuous reinforcing fibers called prepregs, and shaping into the desired shape by heating and pressing with a press or the like Molding is most commonly performed. The fiber reinforced plastic obtained in this way has excellent mechanical properties because it uses continuous reinforcing fibers. Further, by arranging the continuous reinforcing fibers regularly, it is possible to design the required mechanical properties, and the variation in the mechanical properties is small. However, since it is a continuous reinforcing fiber, it is difficult to form a complicated shape such as a three-dimensional shape, and it is mainly limited to members close to a planar shape.

  In order to fill the drawbacks of the above materials, by cutting into a prepreg made of continuous fibers and thermoplastic resin, it can be molded in a short time, and exhibits excellent formability at the time of molding. A laminated base material that is said to exhibit excellent mechanical properties when disclosed (Patent Document 1). Patent Document 1 describes that in the production of a laminated base material, it is preferable to laminate a plurality of cut prepregs, heat the laminated cut prepreg base material, and repeat the pressurization and decompression until a predetermined void ratio is obtained. It is described. Moreover, this patent document 1 has illustrated the double belt press as an apparatus used for manufacture of a laminated base material. The Patent Document 1 does not disclose a method for removing voids between prepreg layers and maintaining the laminated structure of the laminated base material.

  Moreover, as a base material composed of discontinuous fibers and a thermoplastic resin, the ratio of reinforcing fibers having a fiber length of 10 mm out of 100% by weight of reinforcing fibers is 0 to 50% by weight, and the ratio of reinforcing fibers having a fiber length of 2 to 10 mm is A base material made of a prepreg containing reinforcing fibers and a thermoplastic resin, in which the ratio of reinforcing fibers having a fiber length of 50 to 100% by weight and a fiber length of less than 2 mm is 0 to 50% by weight is known (Patent Document 2). This base material also does not disclose a method for removing voids between prepreg layers and maintaining the laminated structure of the laminated base material.

Japanese Patent No. 5167953 Japanese Patent No. 4862913

  The present invention is intended to solve the problems associated with the prior art as described above, and has excellent mechanical properties such as bending strength and tensile elastic modulus applicable to a structural material, and variations in mechanical properties. It is an object of the present invention to provide a method for stably producing a laminated base material that is low, has excellent shapeability into a complicated shape, and can be molded in a short time, and a laminated base material.

  As a result of intensive studies to solve the above problems, the present invention has a ratio of the area of the laminated base material after the integration of the prepreg laminate / the area of the laminated base material before the integration of 1.01 to 1.10. As a result, the inventors have found that it is sufficient to control so that the present invention is completed. That is, the gist of the present invention resides in the following (1) to (18).

  (1) Two or more prepregs containing reinforcing fibers and a thermoplastic resin are laminated, heated while being heated above the melting point or glass transition temperature of the thermoplastic resin while pressing the laminate sandwiched between the plates, It is a method of integration by cooling below the melting point or glass transition temperature of the thermoplastic resin while pressurizing above the pressure, and the ratio of the area of the laminated base material after integration / the area of the laminated base material before integration Is 1.01-1.10, The manufacturing method of the laminated base material characterized by the above-mentioned.

  (2) The production method according to (1), wherein the reinforcing fibers of the prepreg are oriented in one direction.

(3) The laminated base material is a laminated base material obtained by laminating a plurality of prepregs including reinforcing fibers oriented in one direction and a thermoplastic resin, and the prepreg cuts the reinforcing fibers in a direction crossing the reinforcing fibers. It has a depth of cut, the cut is straight, the angle between the cut and the reinforcing fiber is 30 ° or more and 60 ° or less, and the sum of the cut lengths per 1 m ^{2 of the} prepreg is The method for producing a laminated base material as described in (2) above, comprising a prepreg of 20 m or more and 150 m or less.

(4) The laminated base material is a laminated base material in which a plurality of prepregs including reinforcing fibers oriented in one direction and a thermoplastic resin are laminated, and the prepreg cuts the reinforcing fibers in a direction crossing the reinforcing fibers. A notch having a depth, wherein the notch is a curve along a straight center line, and when the curve is projected onto the center line, there is no overlap, and the angle formed by the center line and the reinforcing fiber is The method for producing a laminated base material according to (2) above, comprising a prepreg that is 30 ° or more and 60 ° or less and that has a total cutting depth per 1 m ^{2 of the} prepreg of 20 m or more and 150 m or less. .

  (5) The production of a laminated base material according to (3) or (4) above, wherein the laminated base material contains a prepreg having a length of reinforcing fibers cut by cutting of 10 mm or more and 50 mm or less. Method.

  (6) The laminated base material according to the above (1), wherein the reinforcing fiber constituting the prepreg is 50% to 100% by weight in a fiber length of 2 mm to 10 mm among 100% by weight of the reinforcing fiber. Production method.

  (7) Of the above-mentioned 100% by weight of reinforcing fibers, the ratio of reinforcing fibers having a fiber length of more than 10 mm is 0 to 50% by weight, and the ratio of reinforcing fibers having a fiber length of less than 2 mm is 0 to 50%. The manufacturing method of the laminated base material as described in 6).

  (8) Any of (1) to (5) above, wherein the plurality of prepregs constituting the laminated base material are laminated so that the directions of the reinforcing fibers contained in the prepreg are pseudo-isotropic. The manufacturing method of the laminated base material of description.

  (9) The above (1), wherein the plurality of prepregs constituting the laminated base material are alternately laminated with prepregs in which the direction of reinforcing fibers contained in the prepreg is 0 ° and 90 °. The manufacturing method of the laminated base material in any one of (5).

  (10) The laminated substrate according to any one of (1) to (9), wherein the reinforcing fiber is a carbon fiber having an average single fiber fineness of 0.5 dtex or more and 2.4 dtex or less. Manufacturing method.

  (11) The method for producing a laminated base material according to any one of (1) to (10), wherein the laminated base material further includes a layer made of only a thermoplastic resin.

  (12) The volume content of the reinforcing fibers contained in the prepreg constituting the laminated base material is 20% by volume or more and 55% by volume or less, according to any one of (1) to (11) above The manufacturing method of the laminated base material of this.

  (13) The method for producing a laminated base material according to any one of (1) to (12) above, wherein the thickness of the prepreg constituting the laminated base material is 50 μm or more and 200 μm or less.

  (14) The method for producing a laminated base material according to any one of (1) to (13), wherein prepregs constituting the laminated base material are adhered to each other.

  (15) The method for producing a laminated base material as described in (14) above, wherein the bonding method is performed using thermal welding.

  (16) The method for producing a laminated base material as described in (14) above, wherein the bonding method is performed by vibration welding.

  (17) The method for producing a laminated base material as described in (14) above, wherein the adhesion method is performed using a hot press.

  (18) A laminated substrate produced by any one of the methods (1) to (17).

  According to the present invention, it is excellent in formability to a complicated shape and can be formed in a short time, and has excellent mechanical properties such as bending strength and tensile elastic modulus applicable to a structural material, and a laminate having low variability thereof. The substrate can be stably obtained while removing voids between the prepregs and maintaining the laminated structure of the laminated substrate.

The 1st example of the cutting of the prepreg of this invention. The 2nd example of the cutting of the prepreg of this invention. First example of manufacturing method of laminated substrate Second example of laminated substrate manufacturing method

  In the present invention, two or more prepregs containing reinforcing fibers and a thermoplastic resin are laminated, and the laminate is heated between the melting point of the thermoplastic resin or the glass transition temperature while being pressed between the plates, and then heated. It is related with the manufacturing method of the laminated base material which integrates a laminated body by cooling to below melting | fusing point or glass transition temperature of a thermoplastic resin, pressurizing more than this pressure.

  In the first method disclosed by the present invention, the ratio of the area of the laminated base material after the integration / the area of the laminated base material before the integration is 1.01 to 1.10, which is excellent in mechanical properties and is a reinforcing fiber. A substrate without any disturbance can be obtained. Specifically, by setting the ratio of the area of the laminated base material after integration / the area of the laminated base material before integration to 1.01 or more, voids between prepregs can be reduced and mechanical properties can be reduced. Can be increased. Moreover, by making the ratio of the area of the laminated base material after integration / the area of the laminated base material before integration 1.1 or less, the disturbance of the reinforcing fibers can be suppressed, the appearance is good, and the prepreg A laminated structure can be maintained.

In the second method disclosed in the present invention, it is essential that the reinforcing fibers of the prepreg are oriented in one direction. As a prepreg, it has a notch of the depth which cuts a reinforcing fiber in the direction which crosses a reinforcing fiber, and the said notch is a straight line, Comprising: The angle which a notch and a reinforcing fiber make (theta in Drawing 1 and Drawing 2) Is 30 ° or more and 60 ° or less, and a prepreg having a total cutting length per 1 m ^{2 of the} prepreg of 20 m or more and 150 m or less is used.

In the third method disclosed by the present invention, it is essential that the reinforcing fibers of the prepreg are oriented in one direction. As a prepreg, it has a depth of cut that cuts the reinforcing fiber in a direction crossing the reinforcing fiber, and the notch is a curve along a straight center line, and when the curve is projected onto the center line There is no overlap, the angle between the center line and the reinforcing fiber (θ in FIGS. 1 and 2) is 30 ° or more and 60 ° or less, and the total cutting length per 1 m ^{2 of the} prepreg is 20 m or more and 150 m or less. Use a prepreg that is

  In general, the longer the length of the reinforcing fiber contained in the laminated substrate, the better the mechanical properties, but the fluidity during stamping molding decreases. In order to improve the fluidity during stamping molding, it is effective to cut the reinforcing fiber to a certain length, thereby obtaining a laminated base material that can flow even in complicated three-dimensional shapes such as ribs and bosses. Can do. However, a stamping molding base material made of a cut reinforcing fiber and a resin composition, which is generally called a random material, has a variation in mechanical properties, so that it is difficult to design a part. As a solution to this problem, there has been proposed a laminated base material in which a plurality of prepregs having cuts are laminated, the mechanical properties are good, the variation is small, and the fluidity during stamping molding is excellent.

The fluidity at the time of stamping molding depends not only on the angle θ formed by the notches for cutting the fibers and the reinforcing fibers, but also on the total length la of the notches per 1 m ² . The larger θ is, the smaller the shear force between the fibers is, and thus the higher the fluidity is. The larger la is, the more the cut portion in the prepreg is, the higher the fluidity is. In the case of flat stamping, θ is preferably 25 ° or more, and la is preferably 10 m or more. Furthermore, in the case of stamping molding having a complicated shape such as a rib, θ is preferably 30 ° or more, and la is preferably 20 m or more.

Mechanical properties represented by bending strength and flexural modulus depend not only on the angle θ formed by the notch for cutting the fiber and the reinforcing fiber but also on the total length la of the notch length per 1 m ² . It is known that the smaller the angle θ between the cut and the reinforcing fiber is, the higher the mechanical properties are, and the smaller la is, the smaller the number of cut parts in the prepreg, the higher the mechanical properties. For example, θ is preferably 70 ° or less and la is preferably 200 m or less in order to be used for a semi-structure member of an automobile. For use in structural members that require higher mechanical strength, θ is preferably 60 ° or less, and la is preferably 150 m or less.

The time and manufacturing cost for manufacturing the prepreg with the cut greatly depend not only on the angle θ between the cut for cutting the fiber and the reinforcing fiber but also on the total length la of the cut length per 1 m ² . When θ is small and la is large, and when cutting with a cutting plotter, the time required for the cutting process becomes long. In addition, when the cut is processed by punching, not only the manufacturing cost of the punching blade is increased, but also a tear is easily generated in the direction of the reinforcing fiber when punching, and a sheet is lost between adjacent cuts. Therefore, θ is preferably 15 ° or more, and la is preferably 200 m or less. Further, in consideration of the lamination process after the cutting process, θ is preferably 30 ° or more, and la is more preferably 150 m or less.

The shape of the notch need not be linear. By using the curve, it is possible to increase the total sum la of the cut length per 1 m ² while maintaining the same cut angle and the same fiber length. In this case, an improvement in stamping moldability can be expected while maintaining high mechanical properties.

  In the fourth method disclosed by the present invention, the reinforcing fiber constituting the prepreg uses a prepreg in which the ratio of reinforcing fibers having a fiber length of 2 to 10 mm is 50 to 100% by weight among 100% by weight of the reinforcing fibers. In the prepreg, the total of the reinforcing fiber having a fiber length of more than 10 mm and the reinforcing fiber having a fiber length of less than 2 mm is 0 to 50% by weight, and more preferably, the reinforcing fiber having a fiber length of more than 10 mm out of 100% by weight of the reinforcing fiber. A prepreg having a ratio of 0 to 50% by weight and a ratio of reinforcing fibers having a fiber length of less than 2 mm is 0 to 50% by weight. When the reinforcing fiber longer than 10 mm exceeds 50% by weight, there is a problem that the expansion of the thickness in the laminating process or the molding process becomes large. Moreover, when the reinforcing fiber of less than 2 mm exceeds 50% by weight, the prepreg or the laminate does not have sufficient strength, and there is a problem in handleability, and the physical properties of a molded product obtained from the laminate are deteriorated. is there.

  As the reinforcing fiber that can be used for the prepreg included in the laminated base material of the present invention, the type of the reinforcing fiber is not particularly limited, and inorganic fiber, organic fiber, metal fiber, or a hybrid fiber that combines these is used. Can be used. Examples of the inorganic fiber include carbon fiber, graphite fiber, silicon carbide fiber, alumina fiber, tungsten carbide fiber, boron fiber, and glass fiber. Examples of organic fibers include aramid fibers, high density polyethylene fibers, other general nylon fibers, and polyesters. Examples of the metal fibers include fibers such as stainless steel and iron, and may be carbon fibers coated with metal. Among these, carbon fibers are preferable in consideration of mechanical properties such as strength of the final molded product. Moreover, it is preferable that the average fiber diameter of a reinforced fiber is 1-50 micrometers, and it is more preferable that it is 5-20 micrometers.

  When the reinforcing fiber is a carbon fiber, the average single fiber fineness is preferably a carbon fiber that is 0.5 dtex or more and 2.4 dtex or less. If the average single fiber fineness is too low, it may be difficult to impregnate the carbon fiber with the resin, and if it is too high, the interface area between the carbon fiber and the resin may be reduced. The average single fiber fineness of the reinforcing fibers is more preferably 0.55 to 2.0 dtex or more, and further preferably 0.6 to 1.5 dtex or more.

  It is necessary to use a thermoplastic resin for the prepreg contained in the laminated base material of the present invention. That is, in the case of a fiber reinforced plastic using discontinuous reinforcing fibers, in order to break so as to connect the ends of the reinforcing fibers, it is generally possible to use a thermoplastic resin having a higher toughness value than a thermosetting resin. , Strength, especially impact properties are improved. Furthermore, since the thermoplastic resin is cooled and solidified without a chemical reaction to determine the shape, it can be molded in a short time and has excellent productivity. Examples of such thermoplastic resins include polyamide (nylon 6, nylon 66, aromatic nylon, etc.), polyolefin (polyethylene, polypropylene, etc.), modified polyolefin, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polyamideimide, Polyphenylene oxide, polysulfone, polyether sulfone, polyether ether ketone, polyether imide, polystyrene, ABS, polyphenylene sulfide, liquid crystal polyester, a copolymer of acrylonitrile and styrene, and the like can be used. Moreover, you may use these mixtures. Further, it may be a copolymer of nylon 6 and nylon 66 such as copolymerized nylon. In addition, depending on the required characteristics of the molded product to be obtained, flame retardants, weather resistance improvers, other antioxidants, heat stabilizers, ultraviolet absorbers, plasticizers, lubricants, colorants, compatibilizers, conductive fillers, etc. Can also be added.

  In the first to third methods disclosed by the present invention, the prepreg contained in the laminated base material needs to have the reinforcing fibers cut by cutting. The length L of the cut reinforcing fiber is not particularly limited, but is preferably 5 mm or more and 100 mm or less from the viewpoint of mechanical properties and fluidity. In particular, 10 mm or more and 50 mm or less is more preferable in order to achieve both sufficient mechanical properties and flow to a thin portion such as a rib during stamping molding.

In the laminated base material of the present invention, the prepreg constituting the laminated base material satisfies the range of the sum la of the angle θ formed by the cuts for cutting the fibers and the reinforcing fibers and the cut length per 1 m ^2. For example, prepregs having different lengths of cuts and different numbers of cuts may be laminated. At the time of stamping molding, it is preferable to increase θ and increase la in a thin and three-dimensional portion such as a boss or rib. On the other hand, it is preferable that θ is small and la is small in a portion where the flow is two-dimensional and the flow length is small and high mechanical properties are required.

  In the laminated base material of the present invention, it is preferable that a layer made of only a thermoplastic resin is laminated between a plurality of prepregs constituting the laminated base material in terms of further improving the fluidity during pressing. Such a layer consisting of only a thermoplastic resin is the same resin composition as the resin composition contained in the prepreg, or polyamide (nylon 6, nylon 66, aromatic nylon, etc.), polyolefin (polyethylene, Polypropylene, etc.), modified polyolefin, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polyamideimide, polyphenylene oxide, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polystyrene, ABS, polyphenylene sulfide, liquid crystal polyester Or a copolymer of acrylonitrile and styrene can be preferably used.

  In the laminated base material of the present invention, it is preferable that a plurality of prepregs are laminated so that the directions of the reinforcing fibers are pseudo-isotropic from the viewpoint of reducing flow anisotropy during pressing.

  In the laminated substrate of the present invention, the strength anisotropy of the laminated substrate is reduced by alternately laminating the prepregs in which the directions of the reinforcing fibers contained in the prepreg are 0 ° and 90 °. This is preferable.

  If the fiber volume content Vf is 55% or less, the prepreg contained in the laminated base material of the present invention is preferable because sufficient fluidity can be obtained. The lower the value of Vf, the better the fluidity. However, if the value of Vf is less than 20%, the mechanical properties necessary for the structural material cannot be obtained. Considering the relationship between fluidity and mechanical properties, 20% to 55% is preferable. Such Vf value can be measured based on JIS K7075.

  Since the prepreg contained in the laminated base material of the present invention has a cut, the strength tends to decrease as the thickness of the prepreg to be divided increases, and if it is assumed to be applied to a structural material, The thickness is preferably 200 μm or less. On the other hand, if the thickness is less than 50 μm, it is difficult to handle the prepreg, and the number of prepregs to be laminated becomes extremely large in order to obtain a laminated base material. Therefore, it is preferable that it is 50 micrometers or more and 200 micrometers or less from a viewpoint of productivity.

  The prepreg that can be used for the laminated base material of the present invention is preferably such that the prepregs are bonded to each other in terms of easy handling. Examples of the bonding method include a method using an adhesive and a method of melting a resin contained in a prepreg. In particular, when the resin contained in the prepreg is a thermoplastic resin, the method described in the latter is preferable. Examples of the latter method include a thermal welding method, a vibration welding method, and a hot pressing method. The heat welding method is a method of heating a place to be bonded with a heating plate or the like, and the vibration welding method is a method of melting resin by vibrating and rubbing the place to be welded. This is a method of applying a load by heating the part to be bonded.

  Hereinafter, an embodiment of a method for producing a prepreg that can be used for the laminated base material of the present invention will be described, but the present invention is not particularly limited thereto.

  The prepreg that can be used for the laminated base material of the present invention is prepared by, for example, preparing two sheets of thermoplastic resin in the form of a film, and reinforcing fiber sheets or reinforcing fibers in which reinforcing fibers are arranged in a sheet shape between the two sheets. It can be obtained by sandwiching a mat-like material that is cut and made by a papermaking method, etc., and heating and pressing. More specifically, two sheets of thermoplastic resin are sent out from two rolls, and two sheets of film are sent out from two rolls, and a reinforcing fiber sheet and a reinforcing fiber mat supplied from a roll of a reinforcing fiber sheet and a reinforcing fiber mat. Is sandwiched between two films, and then heated and pressurized. As a means for heating and pressurizing, known means can be used, which requires a multi-step process such as using two or more heat rolls or using multiple pairs of preheating devices and heat rolls. It may be. Here, the thermoplastic resin constituting the film does not have to be one type, and a film made of another type of thermoplastic resin may be further laminated using the apparatus as described above.

  Although the said heating temperature is based also on the kind of thermoplastic resin, it is preferable that it is 100-400 degreeC normally. On the other hand, the pressure during pressurization is preferably 0.1 to 10 MPa. If it is this range, since it can be made to impregnate a thermoplastic resin between the reinforced fiber contained in a prepreg, it is preferable. Moreover, the prepreg which can be used for the laminated base material of this invention can also use the prepreg marketed.

  The prepreg that can be used for the laminated substrate of the present invention can be obtained by making a cut using a laser marker, a cutting plotter, a cutting die, or the like, but the cut was made using a laser marker. It is preferable because it has an effect of processing a complex cut such as a curve or a zigzag line at a high speed, and when the cut is made using a cutting plotter, it is large in size of 2 m or more. This is preferable because the prepreg layer can be processed. Furthermore, it is preferable that the cut is made by using a punching die because there is an effect that processing can be performed at high speed.

  In the next step, the prepreg obtained as described above is laminated so that the direction of the reinforcing fibers is pseudo-isotropic or alternately laminated to create a laminated base material. At this time, a laminated base material spot-welded with an ultrasonic welder can be used for ease of handling. Moreover, it is preferable that the laminated base material of this invention laminate | stacks a prepreg so that it may become 4 ~ 96 layers.

  In the next step, the laminated substrate obtained as described above is heated and pressurized to form an integrated laminated substrate. This process consists of sandwiching the laminated base material between plates and heating while applying pressure. The shape of the plate may be a flat plate or a mold such as a stamping die. Although the material of a plate is not specifically limited, A metal, resin, ceramics, etc. are illustrated. The plate or the mold may be an object for integrating the sheet-type prepreg, or may be a continuous type like a double belt press.

  In the said heating, it heats more than melting | fusing point or glass transition temperature of the thermoplastic resin contained in a laminated base material. Specifically, although it depends on the thermoplastic resin contained in the laminated substrate, it is preferably heated at (melting point or glass transition temperature + 5 ° C.) to (melting point or glass transition temperature + 200 ° C.), more preferably (melting point Or it is preferable to heat at (glass transition temperature +10 degreeC)-(melting | fusing point or glass transition temperature +150 degreeC). Prior to the heating, preliminary heating may be performed. The preheating is preferably from (melting point or glass transition temperature−100 ° C.) to (melting point or glass transition temperature + 100 ° C.). Pressurization may be performed at the time of preheating or may not be performed.

  The pressure applied to the laminated substrate in the pressurization is preferably 0.1 to 10 MPa, and more preferably 0.2 to 2 MPa. The pressure is a value obtained by dividing the pressing force by the area of the laminated base material.

  The heating and pressurizing time is preferably 0.1 to 30 minutes, more preferably 0.5 to 10 minutes.

  A cooling process is implemented after a heating process. By performing the cooling, the thermoplastic resin is solidified, so that the laminated base material can be integrated.

  In the said cooling, it cools below to melting | fusing point or glass transition temperature of the thermoplastic resin contained in a laminated base material. Specifically, although it depends on the thermoplastic resin contained in the laminated substrate, it is preferable to cool at (melting point or glass transition temperature−250 ° C.) to (melting point or glass transition temperature−5 ° C.), more preferably. It is preferable to cool at (melting point or glass transition temperature−200 ° C.) to (melting point or glass transition temperature−10 ° C.).

  The pressure applied to the laminated substrate in the cooling is not less than the pressure during heating. By setting the pressure during cooling to be equal to or higher than the pressure during heating, voids between prepregs can be reduced and mechanical properties can be enhanced. Even if the pressure at the time of cooling is higher than the pressure at the time of heating, since it is lower than the melting point or glass transition temperature of the thermoplastic resin, disturbance of the reinforcing fibers can be suppressed. Lamination after integration with heating temperature above the melting point or glass transition temperature of the thermoplastic resin, cooling temperature below the melting point or glass transition temperature of the thermoplastic resin, and cooling pressure above the heating pressure The ratio of the area of the base material / the area of the laminated base material before integration is 1.01 to 1.10, thereby providing a laminated base having excellent mechanical properties, good appearance, and maintaining a prepreg laminated structure. A material can be obtained.

  The cooling and pressurizing time is preferably 0.1 to 30 minutes, more preferably 0.5 to 10 minutes.

  The thickness of the integrated laminated base material according to the present invention that has undergone the above molding is preferably 0.3 to 10 mm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the invention as described in an Example.

Example 1
Carbon fibers (Mitsubishi Rayon, product name: Pyrofil TR-50S15L, average single fiber diameter of about 7 μm, average single fiber fineness of about 0.6 dtex) are aligned in a plane so that the direction of the reinforcing fibers is one direction. A continuous reinforcing fiber sheet having a basis weight of 72.0 g / m ² was obtained. The both sides of this reinforcing fiber sheet are sandwiched between films made of acid-modified polypropylene resin (acid-modified polypropylene resin: manufactured by Mitsubishi Chemical, product name: Modic P958, melting point 165 ° C., basis weight: 36.4 g / m ² ), and passed through a calendar roll. Then, a reinforcing fiber sheet was impregnated with a thermoplastic resin to obtain a continuous prepreg having a fiber volume content (Vf) of 33%, a thickness of 0.12 mm, a width of 50 cm, and a length of 500 m.

The obtained continuous prepreg is continuously removed by a punching die having a punching blade embedded in a roll, except for the inner portion 5 mm from the end of the sheet, and the length L of the reinforcing fiber is constant 25.0 mm, the average cutting length l = The cutting which cut | disconnects a fiber and the angle theta which a reinforcement fiber makes | forms = 30 degree was performed so that it might be set to 20.0 mm. At this time, the total length of cuts per 1 m ² was la = 80.0 m.

  From the prepreg cut as described above, 16 layers of non-continuous prepreg of 30 cm in length and 30 cm in width are cut out, and the reinforcing fiber direction is pseudo-isotropic ([0 ° / 45 ° / 90 ° / −45 °] s2). The laminated base material was created by spot welding with an ultrasonic welder (manufactured by Emerson Japan, product name: 2000LPt).

The laminated base material thus obtained was placed between metal molds (material, SUS304) having an internal size of 30.5 cm square, pressed at 220 ° C. for 5 minutes at a pressure of 1 MPa, and then 50 at a pressure of 1 MPa. A laminated substrate was obtained by pressing at 3 ° C. for 3 minutes. The laminated base material occupies the whole area inside the mold, and the area was 30.5 cm × 30.5 cm = 930.25 cm ² . The ratio of the area of the laminated base material after integration / the area of the laminated base material before integration was 1.03.

  A bending strength test piece having a length of 100 mm and a width of 25 mm was cut out from the obtained laminated base material so that the fiber directions of the front and back surfaces of the test piece were parallel to the length direction of the test piece. According to the test method specified in JIS K-7074, using a universal testing machine (Instron, product name: Model 4465), the distance between the gauge points is 80 mm, and the crosshead speed is 5.0 mm / min. A test was conducted. The number of test pieces measured was n = 6, the average bending strength was 325 MPa, and the average bending elastic modulus was 28.1 GPa.

(Example 2)
The same operation as in Example 1 was performed except that a mold having an inner dimension of 31 cm square was used. The laminated base material occupies the whole area inside the mold, and the area was 31 cm × 31 cm = 961 cm ² . The ratio of the area of the laminated base material after integration / the area of the laminated base material before integration was 1.07. In the test results carried out in the same manner as in Example 1, the average bending strength was 320 MPa, and the average bending elastic modulus was 27.5 GPa.

(Comparative Example 1)
The same operation as in Example 1 was performed except that a mold having an inner dimension of 30.1 cm square was used. The laminated base material occupies the whole area inside the mold, and the area was 30.1 cm × 30.1 cm = 906 cm ² . The ratio of the area of the laminated base material after integration / the area of the laminated base material before integration was 1.007. When the cross section of the laminated substrate was observed, voids were observed between the layers of the prepreg. In the test results carried out in the same manner as in Example 1, the average bending strength was 300 MPa, and the average bending elastic modulus was 25.8 GPa.

(Comparative Example 2)
The same operation as in Example 1 was performed except that a mold having an inner dimension of 32 cm square was used. The laminated base material occupies the whole area inside the mold, and the area was 32 cm × 32 cm = 1024 cm ² . The ratio of the area of the laminated base material after integration / the area of the laminated base material before integration was 1.14. When the cross section of the laminated substrate was observed, no void was observed between the prepreg layers, but the carbon fibers meandered in each prepreg.

(Comparative Example 3)
The same operation as in Example 1 was performed except that the pressure during cooling was 0.9 MPa. Voids were observed between the prepreg layers of the laminated substrate.

Example 4
A double belt press as shown in FIG. 4 was used instead of the mold. The first half of the double belt press was 220 ° C., the heating zone length was 1.5 m, the second half was 50 ° C., and the cooling zone length was 1.5 m. Moreover, it set so that the same pressure might be applied to a laminated base material in a heating zone and a cooling zone. The belt used was made of iron and had a thickness of 1.5 mm and a width of 350 mm. The distance between the upper and lower belts is set to 1.8 mm, and a 30 cm square laminated substrate consisting of 16 layers is continuously put on the lower belt of the double belt press machine at intervals of 10 cm. A laminated base material was obtained continuously by driving in minutes. The thickness of the laminate before integration was calculated to be 1.92 mm by 0.12 × 16, and the thickness of the laminate after integration was 1.8 mm. Therefore, the ratio of the area of the laminated base material after integration / the area of the laminated base material before integration = thickness before integration / thickness after integration = 1.92 / 1.8 is calculated as 1.067. there were. When the cross section of the laminated substrate was observed, no voids were observed between the prepreg layers. In the test results carried out in the same manner as in Example 1, the average bending strength was 323 MPa, and the average bending elastic modulus was 27.8 GPa.

(Examples 5 and 6)
The same operation as in Example 4 was performed except that the distance between the upper and lower belts was as shown in Table 1.

(Comparative Examples 4 and 5)
The same operation as in Example 4 was performed except that the distance between the upper and lower belts was as shown in Table 1.

(Example 7)
Carbon fiber (manufactured by Mitsubishi Rayon, product name: Pyrofil TR-50S15L) was cut into a total amount of 6 mm to obtain a mat-like reinforcing fiber sheet having a basis weight of 72.0 g / m ² by a papermaking method. Both sides of this reinforcing fiber sheet are sandwiched between films made of acid-modified polypropylene resin (acid-modified polypropylene resin: manufactured by Mitsubishi Chemical, product name: Modic P958, basis weight: 36.4 g / m ² ), and are passed through a calender roll to be a thermoplastic resin. Was impregnated into a reinforcing fiber sheet to obtain a prepreg having a fiber volume content (Vf) of 33%, a thickness of 0.2 mm, a length of 30 cm, and a width of 30 cm. 10 layers of prepregs 30 cm long and 30 cm wide were stacked and spot welded with an ultrasonic welding machine (manufactured by Emerson Japan, product name: 2000LPt) to prepare a laminate.

  And the laminated base material was created by the method similar to Example 4 except the distance between upper and lower belts having been 1.85 mm.

(Example 8, Example 9)
The same operation as in Example 7 was performed except that the distance between the upper and lower belts was as shown in Table 2.

(Comparative Examples 6 and 7)
The same operation as in Example 7 was performed except that the distance between the upper and lower belts was as shown in Table 2.

DESCRIPTION OF SYMBOLS 1, 11: Laminating base material 2: Lower die 3: Upper die 12: Lower belt 13: Upper belt

Claims (18)

  Two or more prepregs containing reinforcing fibers and a thermoplastic resin are laminated, and the laminate is heated between the melting point of the thermoplastic resin or the glass transition temperature while pressing between the plates, and then the pressure exceeds the pressure at the time of heating. It is a method of integrating by cooling below the melting point or glass transition temperature of the thermoplastic resin while applying pressure, and the ratio of the area of the laminated base material after integration / the area of the laminated base material before integration is 1 A method for producing a laminated base material, characterized by being from 0.01 to 1.10.   The manufacturing method according to claim 1, wherein the reinforcing fibers of the prepreg are oriented in one direction. The laminated base material is a laminated base material in which a plurality of prepregs including reinforcing fibers oriented in one direction and a thermoplastic resin are laminated, and the prepreg has a depth of cutting the reinforcing fibers in a direction crossing the reinforcing fibers. Having a notch, the notch is linear, the angle between the notch and the reinforcing fiber is not less than 30 ° and not more than 60 °, and the sum of the notch lengths per 1 m ^{2 of the} prepreg is not less than 20 m, The method for producing a laminated base material according to claim 2, comprising a prepreg having a length of 150 m or less. The laminated base material is a laminated base material in which a plurality of prepregs including reinforcing fibers oriented in one direction and a thermoplastic resin are laminated, and the prepreg has a depth of cutting the reinforcing fibers in a direction crossing the reinforcing fibers. A notch, the notch is a curve along a straight center line, and there is no overlap when the curve is projected onto the center line, and the angle between the center line and the reinforcing fiber is 30 ° or more The method for producing a laminated base material according to claim 2, comprising a prepreg that is 60 ° or less and a total of the cut lengths per 1 m ^{2 of the} prepreg is 20 m or more and 150 m or less.   5. The method for producing a laminated base material according to claim 3, wherein the laminated base material includes a prepreg having a length of reinforcing fibers cut by cutting of 10 mm or more and 50 mm or less.   2. The laminated base material according to claim 1, wherein the reinforcing fiber constituting the prepreg is 50% to 100% by weight of a reinforcing fiber having a fiber length of 2 mm to 10 mm out of 100% by weight of the reinforcing fiber. Method.   The ratio of reinforcing fibers having a fiber length of more than 10 mm out of 100% by weight of reinforcing fibers is 0 to 50% by weight, and the ratio of reinforcing fibers having a fiber length of less than 2 mm is 0 to 50%. The manufacturing method of the laminated base material of this.   The laminated base material according to any one of claims 1 to 5, wherein a plurality of prepregs constituting the laminated base material are laminated so that directions of reinforcing fibers contained in the prepreg are pseudo-isotropic. Manufacturing method.   The plurality of prepregs constituting the laminated base material, wherein the prepregs whose directions of reinforcing fibers contained in the prepreg are 0 ° and prepregs of 90 ° are alternately laminated. The manufacturing method of the laminated base material of crab.   The method for producing a laminated base material according to any one of claims 1 to 9, wherein the reinforcing fibers are carbon fibers having an average single fiber fineness of 0.5 dtex or more and 2.4 dtex or less.   The method for producing a laminated base material according to any one of claims 1 to 10, wherein the laminated base material further includes a layer made of only a thermoplastic resin.   The volume content of the reinforcing fibers contained in the prepreg constituting the laminated base material is 20% by volume or more and 55% by volume or less, and the production of the laminated base material according to any one of claims 1 to 11, Method.   The method for producing a laminated base material according to any one of claims 1 to 12, wherein a thickness of a prepreg constituting the laminated base material is 50 µm or more and 200 µm or less.   The method for producing a laminated base material according to any one of claims 1 to 13, wherein the prepregs constituting the laminated base material are adhered to each other.   The method for producing a laminated base material according to claim 14, wherein the bonding method is performed using heat welding.   The method for producing a laminated base material according to claim 14, wherein the adhesion method is performed using vibration welding.   The method for producing a laminated base material according to claim 14, wherein the bonding method is performed using a hot press.   The laminated base material manufactured by the method in any one of Claims 1-17.