JP2018122523A - Bagging sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate wrinkles when a reinforced fiber substrate follows a three-dimensional shaped surface of a mold, control the uniformity of the plate thickness of a molding product, and obtain a complicated three-dimensional shaped fiber-reinforced plastic with a corner, a curve or a bent shape.SOLUTION: A bagging sheet, covering a whole reinforced fiber substrate placed on a mold and used for shaping the reinforced fiber substrate into a mold shape in a vacuum condition, is constituted to have portions with different expansion ratios according to the configuration of a three-dimensional shape of the reinforced fiber substrate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bagging sheet for use in molding by pressing the inside of a bagging sheet under vacuum and pressing a reinforcing fiber substrate against a mold, and in particular, manufacturing a fiber reinforced plastic having a complicated shape such as a curved or bent mold. It is related with the bagging sheet suitable for.

  In recent years, fiber reinforced plastic capable of reducing the weight of components has been widely used as a material due to increasing interest in global environmental problems. The fiber reinforced plastic is manufactured by placing the reinforcing fiber base on a mold of the desired shape and curing the matrix resin impregnated in the reinforcing fiber base to integrate the reinforcing fiber and the matrix resin. The method to do is common.

As a method for producing fiber-reinforced plastics, molded under pressure press the upper and lower mold a reinforcing fiber base material with a lower mold and the upper mold of the desired shape RTM (R esin T ransfer M olding ) method or SMC ( and S heet M olding C ompaund) method compression molding method such as by placing the reinforcing fiber base material on the lower mold of the desired shape, the upper reinforcing fiber substrate is covered with Bagingushito such as a film material, there are Bagingushito internal prepreg process to mold against the mold a reinforcing fiber base material was vacuum aspirated and VaRTM (V acuum a ssisted R esin T ransfer M olding) method bagging molding method such as.

  The RTM method uses two upper and lower molds and a press device for pressurization, so that the plate thickness can be controlled with high accuracy, but the equipment is large and complex, and it is expensive. There is a problem that requires equipment costs.

  In contrast, in the VaRTM method, a reinforcing fiber base is disposed on a mold, the entire reinforcing fiber base is sealed with a bagging sheet, the inside of the bagging sheet is depressurized, and the inside of the bagging sheet and the external pressure are reduced. This is a method of injecting a resin into a reinforced fiber base using a differential pressure with respect to (atmospheric pressure), curing the resin, and demolding after curing to obtain a fiber reinforced plastic. The VaRTM method has the advantage that it can be manufactured with a very simple equipment consisting only of the lower mold and the heating device, but the plate thickness of the reinforcing fiber base is difficult to be uniform with respect to a shape having a complicated shape such as an uneven portion. There are challenges. That is, when the entire reinforcing fiber base is sealed with a bagging sheet and the bagging sheet is decompressed, excessive shaping pressure is locally applied due to the convex shape, and the bagging sheet does not adhere to the concave portion. In some cases, the thickness of the reinforcing fiber substrate becomes non-uniform due to the occurrence of bridging or the occurrence of wrinkles due to the fact that the bagging sheet cannot suppress the out-of-plane deformation. When the matrix resin is injected in such a state that the plate thickness is not uniform, the resin hardens without spreading over the entire reinforcing fiber base material, and there is a problem that a non-impregnated portion of the resin is formed in the molded product. There was a problem that the mechanical properties deteriorated due to the non-uniform thickness.

  In Patent Document 1 (Japanese Patent Laid-Open No. 2001-47507), “a prepreg made of fiber-reinforced plastic is stacked on a lower mold for product production, and this prepreg is covered with a silicon rubber sheet. A bagging method is described in which a mold is sealed, a vacuum is drawn between the lower mold and the silicon rubber sheet, and the prepreg is cured by an autoclave method, and a vacuum is drawn between the lower mold and the silicon rubber sheet. By heating while heating, the silicon rubber sheet adheres to the lower mold side, and the prepreg can be heat-cured to a shape that follows the shape of the lower mold, allowing easy bagging, reducing man-hours and economy The effect of “improvement can be achieved” is disclosed.

  However, in the method of Patent Document 1, when a silicon rubber sheet having a high expansion / contraction ratio is used for an uneven surface having a three-dimensional shape, wrinkles occur because the silicon rubber sheet cannot suppress out-of-plane deformation. In addition, if a silicon rubber sheet with a low expansion / contraction ratio is used, excessive shaping pressure is locally applied due to the convex shape, and further bridges are generated due to the concave shape, resulting in a reduction in the plate thickness. There is a problem of non-uniformity.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 2006-212877), “a pressure bag that covers a prepreg in order to evacuate a prepreg placed on a mold in molding of a composite material molded article is a silicon rubber sheet. By producing a pressure bag using pre-sheet-shaped silicon rubber made of unvulcanized silicon, uniform thickness can be obtained without the need for complicated work of attaching sheet-shaped unvulcanized silicon. Furthermore, the unvulcanized silicon is placed on the cubic curved surface portion and / or corner portion of the mold, and the silicon rubber sheet is placed on the flat portion of the mold. Thus, an effect of being able to obtain a pressure bag having a complicated three-dimensional shape is disclosed.

  However, in the method of Patent Document 2, if a pressure bag having a three-dimensional shape is used in the step of shaping the reinforcing fiber base into a shape having an uneven surface, the difference in circumference of the reinforcing fiber substrate caused by the uneven surface Is not sufficiently stretched to escape, and there is a problem that a large number of wrinkles are generated in the reinforcing fiber base material.

JP 2001-47507 A Japanese Patent Laid-Open No. 2006-212877

  Therefore, in view of the problems of the prior art, the present invention can control the thickness of the molded product to be uniform when the reinforcing fiber substrate follows the three-dimensional shape surface of the mold, An object of the present invention is to provide a bagging sheet capable of molding a fiber reinforced plastic having a complicated three-dimensional shape having a bent shape.

In order to solve the above problems, the present invention employs the following means. That is,
(1) A bagging sheet that covers the entire reinforcing fiber base disposed on a mold and is used for shaping the reinforcing fiber base into a mold shape under reduced pressure, and is a tertiary of the reinforcing fiber base. A bagging sheet characterized by comprising different expansion / contraction ratio portions depending on the form of the original shape.
(2) The bagging sheet according to (1), wherein the different stretch ratio portions are portions where the thickness of the bagging sheet is partially different.
(3) The bagging sheet according to (2), wherein the bagging sheet is 1.2 to 25 times thicker.
(4) The thickness of the low stretch ratio part is 0.1 to 0.5 mm, and the thickness of the part other than the low stretch ratio part is 0.02 to 0.1 mm (2) or ( The bagging sheet according to 3).
(5) The elongation at break of the low stretch ratio part is 100 to 200%, and the break elongation of parts other than the low stretch part is 350 to 1000% (1) to (4) A bagging sheet according to any of the above.
(6) The bagging sheet according to any one of (1) to (5), wherein the different stretch rate portions are portions where a bagging sheet having a lower stretch rate than the bagging sheet is partially adhered.
(7) The three-dimensional shape of the reinforcing fiber substrate is any one of a flat shape, a convex shape, or a concave shape, and the expansion / contraction rate of the portion corresponding to the bent shape portion shaped into the convex shape is The bagging according to any one of claims (1) to (6), characterized in that the low expansion / contraction rate part is lower than the expansion / contraction rate of the part corresponding to the flat shape or the part to be shaped into the concave shape. Sheet.

  When the reinforcing fiber substrate follows the three-dimensional shape surface of the mold, it can be controlled so that there is no wrinkle and the plate thickness of the molded product is uniform, and the complex three-dimensional shape with corners, curved or bent shapes Fiber reinforced plastic can be molded.

It is the top view and side surface sectional view which show the state which covered the reinforced fiber base material arrange | positioned on the shaping | molding die using the bagging sheet which concerns on this invention. It is side surface sectional drawing which shows the state which shape | molded the reinforcement fiber base material in the three-dimensional shape by vacuum suction using the bagging sheet which concerns on this invention. It is an expanded sectional view which shows the state which shape | molded the reinforced fiber base material along the curved surface shape of a shaping | molding die by vacuum suction using the bagging sheet which concerns on this invention. It is an expanded sectional view which shows the state which shaped the reinforcement fiber base material along the curved surface shape of the shaping | molding die by vacuum suction using the conventional bagging sheet. It is an expanded sectional view which shows the state which shaped the reinforcement fiber base material along the curved surface shape of the shaping | molding die by vacuum suction using the conventional bagging sheet.

  Hereinafter, embodiments of the present invention will be sequentially described. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  The bagging sheet 3 according to the present invention is a bagging sheet 3 that covers the entire reinforcing fiber base 2 disposed on the mold 1 and is used for shaping the reinforcing fiber base 2 into a mold shape under reduced pressure. Thus, the reinforcing fiber base 2 has a different stretch ratio depending on the shape of the three-dimensional shape.

  In the bagging sheet 3 according to the present invention, as shown in the plan view and the side sectional view of FIG. 1, the reinforcing fiber base 2 is arranged on a molding die 1 having a desired three-dimensional shape having a convex bent shape. Then, the reinforcing fiber base 2 is covered with the bagging sheet 3 and the periphery is sealed with the sealing 4. FIG. 1 shows a form of a laminated body in which a plurality of reinforcing fiber substrates 2 are stacked, and the bagging sheet 3 is disposed so as to protrude beyond the end portion 7 of the reinforcing fiber substrate 2.

  Thereafter, the inside of the bagging sheet 3 is sucked with a vacuum pump 5 under reduced pressure, thereby pressing the bagging sheet 3 against the mold 1 as shown in the side sectional view of FIG. It is shaped along with it. At that time, when the bagging sheet 3 according to the present invention is used, as shown in FIG. 3 in which the bent shape portion 6 of the mold 1 is enlarged, the compression state of the laminated reinforcing fiber base material 2 in the vicinity of the bent shape portion 6 is The shape is formed almost unchanged from the compressed state of the flat portion in the vicinity other than the bent shape portion 6. This is because the entire periphery of the bagging sheet 3 is shaped using the low tension of the high expansion / contraction rate sheet portion 8, so that it does not receive excessive shaping pressure in the vicinity of the bent shape portion 6, and is applied to the mold 1 side. It is because it can suppress pushing in locally. Furthermore, since the low expansion / contraction rate sheet portion 9 is arranged in advance near the bent shape portion 6, the shape change of the reinforcing fiber base 2 outside the surface of the bagging sheet 3 at this portion is suppressed, and local Generation of general wrinkles can be suppressed and the thickness can be controlled.

  On the other hand, when forming only with the conventional single bagging sheet 3, the reinforcing fiber base material 2 is covered with the bagging sheet 3, and the reinforcing fiber base material 2 is formed into a mold by sucking the inside of the bagging sheet 3 under reduced pressure. 4, the bagging sheet 3 has a low expansion / contraction rate, and as shown in FIG. In some cases, the base material 2 is pushed to the mold 1 side at the bent portion 6 to cause a bias, and the fiber density is likely to be higher than that of the flat surface portion.

  Further, when the expansion ratio of the bagging sheet is high, as shown in FIG. 5, the thickness of the reinforcing fiber substrate 2 is pushed into the mold 1 with a weak shaping pressure in the vicinity of the bent portion 6, and the vacuum suction process thereafter. Depending on the process in which wrinkles change, wrinkles may occur near the bent portion 6. Injecting the matrix resin in such a state may cause uneven distribution of the resin impregnation, and further, the thickness of the molded product after the resin is cured may be uneven.

  Thus, it is important to provide the bagging sheet 3 with partially different stretch ratio portions. In the present invention, the different expansion / contraction ratio parts are preferably parts where the thickness of the bagging sheet 3 is partially different.

  As shown in FIG. 1, in order to provide the bagging sheet 3 with a different stretch ratio portion, the high stretch ratio sheet portion 8 and the low stretch ratio sheet portion 9 having a different thickness are provided. By taking a means for making the thickness partially different, it is possible to appropriately cope with a place where it is necessary to change the shaping pressure on the reinforcing fiber base 2 by a simple method.

  Moreover, in this invention, it is preferable to make the site | part which thickened the thickness of the bagging sheet 3 1.2 to 25 times into a low expansion-contraction rate site | part.

  By changing the thickness of the bagging sheet 3, the shaping pressure on the reinforcing fiber substrate 2 can be adjusted according to the three-dimensional shape of the mold. Preferably, the thickness of the bagging sheet 3 is 2 to 22 times, more preferably 5 to 20 times.

  If the thickness of the low expansion / contraction part of the bagging sheet 3 is less than 1.2 times the thickness of the part other than the low expansion / contraction part of the bagging sheet 3, the shaping pressure applied to the reinforcing fiber substrate 2 is changed. When the thickness of the low expansion / contraction part of the bagging sheet 3 exceeds 25 times the thickness of the part other than the low expansion / contraction part of the bagging sheet 3, the three-dimensional shape of the mold is maintained. In some cases, it may be difficult to shape them.

  Moreover, in this invention, it is preferable that the thickness of the low expansion-contraction part of the bagging sheet 3 is 0.1-0.5 mm, and the thickness of parts other than a low expansion-contraction part is 0.02-0.1 mm.

  By setting the bagging sheet 3 to a predetermined thickness, the shaping pressure on the reinforcing fiber base 2 can be adjusted according to the shape of the three-dimensional mold. Preferably, the thickness of the low stretch ratio part of the bagging sheet 3 is 0.2 to 0.4 mm, and the thickness of parts other than the low stretch ratio part is 0.04 to 0.08 mm, more preferably the low stretch ratio part. The thickness of the part is 0.25 to 0.35 mm, and the thickness of parts other than the low stretch ratio part is 0.05 to 0.07 mm.

  When the thickness of the low stretch ratio portion of the bagging sheet 3 is less than 0.1 mm, it becomes impossible to suppress the shape change of the reinforcing fiber base 2 out of the bagging sheet 3 when shaping the bent portion 6. In some cases, when the thickness of the low expansion / contraction ratio portion of the bagging sheet 3 exceeds 0.5 mm, it may be difficult to shape the bagging sheet 3 along the three-dimensional shape.

  If the thickness of the bagging sheet 3 other than the low expansion / contraction part is less than 0.02 mm, there is a risk that the bagging sheet 3 is broken in the process of shaping the bagging sheet 3 along the three-dimensional shape of the mold. Rise. Further, in the process of shaping the bagging sheet 3 along the mold 1, the reinforcing fiber base 2 is pushed into the bent shape part 6 with a weak shaping pressure, and the reinforcing fiber base 2 is then pressed in the subsequent vacuum suction process. Depending on the process of changing the thickness, wrinkles may occur near the bent portion 6. On the other hand, when the thickness of the part other than the low expansion / contraction part of the bagging sheet 3 exceeds 0.1 mm, in the process of shaping the bagging sheet 3 along the three-dimensional shape of the mold, The reinforcing fiber base material 2 receives an excessive shaping pressure, and the reinforcing fiber base material 2 is locally pushed into the mold 1 side.

  Moreover, in this invention, it is preferable that the breaking elongation of a low expansion-contraction part is 100 to 200%, and the breaking elongation of parts other than a low expansion-contraction part is 350 to 1000%.

  By defining the breaking elongation of the low expansion / contraction ratio part of the bagging sheet 3 within a certain range, the shaping pressure on the reinforcing fiber base 2 can be adjusted according to the three-dimensional shape of the mold. Preferably, the elongation at break of the low stretch ratio part is 120 to 180%, the break elongation at the part other than the low stretch ratio part is 400 to 900%, and more preferably, the break elongation of the low stretch part is 140. ~ 160%, the elongation at break of the part other than the low stretch ratio part is 500 to 800%.

  If the elongation at break of the low stretch ratio portion of the bagging sheet 3 is less than 100%, it may be difficult to form the bagging sheet 3 along the shape of the three-dimensional mold. If the breaking elongation at the rate portion exceeds 200%, the shape change of the reinforcing fiber base 2 outside the bagging sheet 3 may not be suppressed when the bent shape portion 6 is shaped.

  If the elongation at break of the bagging sheet 3 other than the low expansion ratio is less than 350%, in the process of shaping the bagging sheet 3 along the shape of the three-dimensional mold, the bent part 6 is near the bent part 6. The reinforcing fiber base material 2 receives an excessive shaping pressure, and the reinforcing fiber base material 2 is locally pushed into the mold 1 side. On the other hand, when the elongation at break of the bagging sheet 3 other than the low expansion / contraction ratio exceeds 1000%, the reinforcing fiber base 2 is weakly applied in the process of shaping the bagging sheet 3 along the mold 1. Wrinkles may occur in the vicinity of the bent shape portion 6 depending on the process of being pushed into the bent shape portion 6 by the forming pressure and the thickness of the reinforcing fiber substrate 2 changing in the subsequent vacuum suction process.

  The material of the bagging sheet 3 is not particularly limited as long as it is stretchable, flexible enough to perform bagging work, heat resistant at high temperatures, and resistant to tearing and pinholes. However, an impermeable sheet mainly composed of a polyamide resin or a polyester resin can be preferably used.

  Moreover, in this invention, it is preferable to adhere | attach a low expansion-contraction sheet partially with respect to a high expansion-contraction sheet. Thereby, the bagging sheet 3 which comprises the expansion-contraction rate part which changes according to the form of the three-dimensional shape of the reinforced fiber base material 2 can be produced easily.

  In the present invention, the three-dimensional shape of the reinforcing fiber base 2 is any one of a flat shape, a convex shape, or a concave shape, and the expansion / contraction rate of a portion corresponding to the bent shape portion 6 shaped into the convex shape. However, it is preferable that it is a low expansion / contraction rate site | part lower than the expansion / contraction rate of the site | part corresponding to the location shape | molded in a flat shape or a concave shape.

  Thereby, it can respond | correspond appropriately to the location which needs to change the shaping pressure to a reinforcement fiber base material. When the reinforcing fiber base material 2 is shaped in the bent shape portion 6 of the mold 1, the occurrence of wrinkles can be effectively achieved by using the bagging sheet portion corresponding to the bent shape portion 6 of the mold 1 as the low stretch ratio sheet portion 9. Can be suppressed.

  Thus, the configuration of the bagging sheet 3 is a configuration having the high stretch rate sheet portion 8 and the low stretch rate sheet portion 9, and the configuration pattern of the high stretch rate sheet portion 8 and the low stretch rate sheet portion 9 is a reinforcing fiber base. By providing appropriately according to the form of the three-dimensional shape of the material 2, it is possible to uniformly mold the thickness of the molded product without wrinkles.

  The reinforcing fiber substrate 2 used in the present invention may be a sheet-like prepreg material in which a resin is impregnated in advance with a reinforcing fiber, or may be a dry reinforcing fiber substrate in which a resin is not impregnated. . The form of the reinforcing fiber base 2 is not particularly limited as long as it can be shaped into the three-dimensional mold 1, but a bi-directional woven fabric using reinforcing fiber bundles such as plain weave, twill weave, satin weave and the like is used. Other examples include unidirectional weaves in which the warp yarns are thin wefts, and multiaxial weaves in which base materials made of unidirectional weaves are stacked. Glass fibers, aramid fibers, carbon fibers, etc. are suitable as the material for the reinforcing fiber bundle. Used for.

  In the case where the reinforcing fiber substrate 2 is a sheet-like prepreg material in which a reinforcing fiber is pre-impregnated with a resin, the bagging sheet 3 is used to cover the entire reinforcing fiber substrate 2 arranged on the mold and in a reduced pressure state. A fiber reinforced plastic is formed by shaping the reinforcing fiber substrate into a three-dimensional shape and then curing it.

  In the case of the dry reinforcing fiber base material 2, the reinforcing fiber base material 2 is covered with a bagging sheet 3, the inside of the bagging sheet 3 is sucked under reduced pressure, shaped into a three-dimensional shape, and then thermoset into a reduced pressure molding space. A fiber reinforced plastic is formed by injecting a liquid resin mainly composed of a functional resin, injecting and impregnating the reinforcing fiber base material 2 with the liquid resin, and curing the liquid resin impregnated in the reinforcing fiber base material 2. .

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to these Examples.

Example 1
A nylon film having a breaking elongation of 400% and a thickness of 0.05 mm is applied to the high stretching ratio sheet portion 8 of the bagging sheet 3, and a polyester film having a breaking elongation of 200% and a thickness of 0.2 mm is applied to the low stretching ratio sheet portion 9. Was applied to produce a bagging sheet A (3) partially having a portion with a different stretch ratio. The reinforcing fiber base material 2 is disposed on the mold 1 having the bent shape 6 so that the laminate thickness is 3 mm, and the low expansion / contraction ratio sheet portion 9 of the bagging sheet A (3) becomes the bent shape portion 6 of the mold. Correspondingly, the reinforcing fiber base 2 was covered with the bagging sheet A (3), and the reinforcing fiber base 2 was shaped by sucking the inside of the bagging sheet A (3) under reduced pressure. Thereafter, the reinforcing fiber base material was impregnated with a matrix resin, and the resin was cured to obtain a molded product. The obtained molded product was a molded product having a good surface design with no occurrence of wrinkles in the bent portion.

(Comparative Example 1)
Two reinforcing fiber bases are arranged on the mold 1 having the bent shape 6 so that the laminate thickness is 3 mm, and the bagging sheet 3 is a bagging whose entire surface is a nylon film having a breaking elongation of 400% and a thickness of 0.05 mm. The reinforcing fiber base material 2 was shaped by covering the reinforcing fiber base material 2 with the film B (3) and sucking the inside of the bagging sheet B (3) under reduced pressure. Thereafter, the reinforcing fiber substrate 2 was impregnated with a matrix resin, and the resin was cured to obtain a molded product. The obtained molded product was a molded product having a poor surface design with wrinkles occurring in the bent portion.

  Due to the above characteristics, the composite structure of the present invention is preferably used as a component or member for electrical and electronic equipment casings and internal members, automobiles, two-wheeled vehicles, aircraft, building materials, and the like that can be suitably used for various applications such as Can be used.

DESCRIPTION OF SYMBOLS 1 Mold 2 Reinforcement fiber base material 3 Bagging sheet 4 Sealing 5 Vacuum pump 6 Bending shape part 7 Reinforcement fiber base material edge 8 High stretch ratio sheet part 9 Low stretch ratio sheet part

Claims (7)

A bagging sheet that covers the entire reinforcing fiber base disposed on a mold and is used for shaping the reinforcing fiber base into a mold shape under reduced pressure, wherein the reinforcing fiber base has a three-dimensional shape. A bagging sheet characterized by having different expansion / contraction ratio parts depending on the form. The bagging sheet according to claim 1, wherein the different expansion / contraction ratio parts are parts where the thickness of the bagging sheet is partially different. The bagging sheet according to claim 2, wherein the thickness of the bagging sheet is increased by 1.2 to 25 times. The thickness of a low stretch ratio part is 0.1 to 0.5 mm, and the thickness of parts other than the low stretch part is 0.02 to 0.1 mm. Bagging sheet. The breaking elongation of a low stretch ratio part is 100 to 200%, and the breaking elongation of a part other than the low stretch ratio part is 350 to 1000%. Bagging sheet. The bagging sheet according to any one of claims 1 to 5, wherein the different stretch rate portions are portions where a bagging sheet having a lower stretch rate than the bagging sheet is partially adhered. The three-dimensional shape of the reinforcing fiber substrate is any one of a flat shape, a convex shape, or a concave shape, and the expansion / contraction rate of the portion corresponding to the bent shape portion shaped into the convex shape is the flat shape. The bagging sheet according to any one of claims 1 to 6, wherein the bagging sheet is the low expansion / contraction rate part lower than the expansion / contraction rate of the part corresponding to the part to be shaped into the concave shape.