WO1989010833A1 - Method for moulding of fibre-reinforced articles - Google Patents

Method for moulding of fibre-reinforced articles Download PDF

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Publication number
WO1989010833A1
WO1989010833A1 PCT/NL1989/000034 NL8900034W WO8910833A1 WO 1989010833 A1 WO1989010833 A1 WO 1989010833A1 NL 8900034 W NL8900034 W NL 8900034W WO 8910833 A1 WO8910833 A1 WO 8910833A1
Authority
WO
WIPO (PCT)
Prior art keywords
resin
layers
mould
fibre
fibre material
Prior art date
Application number
PCT/NL1989/000034
Other languages
French (fr)
Inventor
Jan Van Turnhout
Louis Petrus Valentijn Marie Van Rijn
Original Assignee
Nederlandse Organisatie Voor Toegepast-Natuurweten
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nederlandse Organisatie Voor Toegepast-Natuurweten filed Critical Nederlandse Organisatie Voor Toegepast-Natuurweten
Publication of WO1989010833A1 publication Critical patent/WO1989010833A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/12—Incorporating or moulding on preformed parts, e.g. inserts or reinforcements
    • B29C44/14—Incorporating or moulding on preformed parts, e.g. inserts or reinforcements the preformed part being a lining
    • B29C44/16—Incorporating or moulding on preformed parts, e.g. inserts or reinforcements the preformed part being a lining shaped by the expansion of the material

Definitions

  • the present invention relates to a method for the production of fibre-reinforced articles, with which method a number of layers of fibre material are introduced into a mould and impregnated with resin and the resin is cured.
  • the resin used with this method can be, for example, epoxy resin, polyester resin or vinyl ester resin or a silicone resin or polyurethane resin.
  • the first three resins give a hard product on curing and the last two a flexible rubber resin product.
  • the fibre material used with this method can be a non-woven, woven fabric or knitted fabric, consisting of fibres of glass, plastic or metal or of a combination of such fibres.
  • the fibre layers are, for example, each spread separately with fluid resin.
  • the product thus obtained therefore consists of a resin matrix in which the layers of fibre material are embedded.
  • the layers are placed on a mould under an airtight film, after which a partial vacuum is created in the space between mould and film and resin is admitted to said space ("resin transfer moulding").
  • resin can also be injected under an excess pressure into the space in which the vacuum has been created; the strength (thickness) of the film must, of course, be adjusted in this case.
  • the closed method has the advantage that it is cleaner, more environmentally friendly and less labour-intensive; moreover, it yields better products since the formation of air pores during impregnation is avoided.
  • a sandwich construction of this type has, of course, a greater stiffness in flexure, while the weight is the same as that of the above entioned product.
  • the aim of the invention is, therefore, to provide a method of the type named in the preamble with which fibre-reinforced products with a foam core can also be produced in a single operation.
  • the volume of the resin is increased, the fibre layer or layers being pushed away towards the outside of the resin body.
  • One or more layers of fibre material can be used.
  • the volume of the resin present between the fibre layer and the mould surface is increased.
  • at least two layers of fibre material are used; in this case the volume of the resin in between the layers is increased.
  • the volume of the resin is increased by foaming the resin, the viscosity and surface tension of the resin and the porosity of the fibre material being such that the layers impregnated with resin cannot be penetrated by the foaming resin.
  • foaming of the resin the known means suitable for this purpose can be used.
  • the volume of the resin is increased by feeding a resin filled with a filler between the layers of fibre material.
  • the filler can consist, for example, of small hollow or expandable spheres. In this case also means known per se can be used for forming such small hollow or expandable spheres.
  • Other fillers can also be used, for example wood flour, powdered quartz and the like.
  • short fibres can be used as filler. Fibres of this type increase the strength of the finished product. Elastomeric particles can also be used as filler; the finished product then has better impact resistance.
  • an airtight film is fitted on the package consisting of the layers of fibre material, the edges of the film are sealed airtight, a partial vacuum is created in the space between film and mould and the resin is admitted into said space in order to impregnate the fibre material.
  • the film When the layers of fibre material are pressed apart, the film must therefore move with them.
  • this is achieved in that the film fitted is oversize such that, during foaming, the film can move over the required distance with the sheets of fibre material when these are pushed apart. If a stretchable film is used with this procedure, a regular, smooth surface is obtained after curing of the foamed resin.
  • the lower mould half is preferably that having the smallest length in cross- section. Consequently it is relatively flat, which makes it easier to lay the layers of fibre material.
  • an article with differently moulded surfaces can now also be produced in that the upper layer of fibre material is inserted pleated, such that where the upper profile has a greater length than the lower profile there is a pleat in the uppermost fibre layer with an oversize of material relative to the lower fibre layer such that after the uppermost fibre layer has been pushed upwards this lies without pleats against the upper profile.
  • the procedure is that the resin is injected as a mixture with foaming agent.
  • a resin without foaming agent is first introduced and then a resin with foaming agent is introduced.
  • the two resins can differ or can be identical.
  • epoxy resin can be used for the outside and a hard polyurethane resin for the core.
  • Fig. 1 shows a mould during a first phase of the method.
  • Fig. 2 shows the mould of Fig. 1 during a second phase.
  • Fig. 3 shows the mould of Fig. 1 during a third phase.
  • Fig. 4 shows a second mould for carrying out the method according to the invention, before foaming.
  • Fig. 5 shows the mould of Fig. 4, after foaming.
  • the mould shown in Fig. 1 consists of a lower half 1 and an upper half 2.
  • a number of layers of fibre material 3 have been laid in the lower half 1 and covered by a film 4.
  • the edges of the film 4 have been clamped between the edges of the mould halves 1 and 2 so as to provide a seal.
  • a partial vacuum is applied to the space between the film 4 and the mould half 1 via the connection 5, after which resin is injected via the connection 6.
  • Fig. 2 shows how the front 7 of resin spreads through the package of fibre layers 3.
  • a foaming agent is injected via the injection point 8 into the resin between the layers of fibre material.
  • Fig. 4 shows a second mould in which the shape of the upper half of the mould deviates from that of the lower half.
  • the film 4 and the uppermost layer of fibre material 3 are provided with a pleat 11 and 12 respectively.

Abstract

In a method for moulding fibre reinforced articles with a foam core, an outer fibre layer (3) is placed in a mould (1, 2) and impregnated by injecting resin (7). Upon injecting the resin (7), the fibre layer is pressed towards the wall of the mould. Thereafter, and before hardening of the resin, a core material is injected for forming the foam core (14). The mould applied may consist partly of a foil (4) (11) which is movable together with the fibre layer (3) towards the wall of the mould (2).

Description

Method for moulding of fibre-reinforced articles
The present invention relates to a method for the production of fibre-reinforced articles, with which method a number of layers of fibre material are introduced into a mould and impregnated with resin and the resin is cured. The resin used with this method can be, for example, epoxy resin, polyester resin or vinyl ester resin or a silicone resin or polyurethane resin. The first three resins give a hard product on curing and the last two a flexible rubber resin product. The fibre material used with this method can be a non-woven, woven fabric or knitted fabric, consisting of fibres of glass, plastic or metal or of a combination of such fibres.
A method of this type is known. With this method, according to a first possibility, the fibre layers are, for example, each spread separately with fluid resin. The product thus obtained therefore consists of a resin matrix in which the layers of fibre material are embedded.
According to another possibility, the layers are placed on a mould under an airtight film, after which a partial vacuum is created in the space between mould and film and resin is admitted to said space ("resin transfer moulding"). With this procedure the resin can also be injected under an excess pressure into the space in which the vacuum has been created; the strength (thickness) of the film must, of course, be adjusted in this case. The closed method has the advantage that it is cleaner, more environmentally friendly and less labour-intensive; moreover, it yields better products since the formation of air pores during impregnation is avoided.
For certain applications it is desirable to introduce a foam core between the layers of fibre material. A sandwich construction of this type has, of course, a greater stiffness in flexure, while the weight is the same as that of the above entioned product.
Attempts have been made, for this purpose, to position blocks of foam material between the layers before they are impregnated with resin. However, with this procedure there is a great risk that, despite the generation of vacuum, the layers of fibre material will still not be impregnated well, so that air pores could form in the resin. These phenomena are caused by the fact that the surface of the foam material is not completely flat, as a result of which differences in thickness arise in the space in which the fibre material is located. As a result, the flow rate of the resin will vary appreciably in said space, with the consequence that air pores (tongues) form. A further disadvantage is that cutting the foam blocks to size and positioning is labour-intensive. Finally, it is a disadvantage that the foam blocks and the fibre material do not adhere well at the boundary surfaces, so that delamination can occur.
The aim of the invention is, therefore, to provide a method of the type named in the preamble with which fibre-reinforced products with a foam core can also be produced in a single operation.
This is achieved in that, after impregnation, the volume of the resin is increased, the fibre layer or layers being pushed away towards the outside of the resin body. One or more layers of fibre material can be used. In the first case, the volume of the resin present between the fibre layer and the mould surface is increased. Preferably, however, at least two layers of fibre material are used; in this case the volume of the resin in between the layers is increased. In this way a product is obtained which has a foam core surrounded on either side by fibre layers embedded therein, which product is light and stiff in flexure, while all parts adhere well to one another.
According to a first preferred procedure, provision is made that the volume of the resin is increased by foaming the resin, the viscosity and surface tension of the resin and the porosity of the fibre material being such that the layers impregnated with resin cannot be penetrated by the foaming resin. With regard to the foaming of the resin, the known means suitable for this purpose can be used. According to a second preferred possibility, provision is made that the volume of the resin is increased by feeding a resin filled with a filler between the layers of fibre material. The filler can consist, for example, of small hollow or expandable spheres. In this case also means known per se can be used for forming such small hollow or expandable spheres. Other fillers can also be used, for example wood flour, powdered quartz and the like. Furthermore, short fibres can be used as filler. Fibres of this type increase the strength of the finished product. Elastomeric particles can also be used as filler; the finished product then has better impact resistance.
According to a known method, provision is made that an airtight film is fitted on the package consisting of the layers of fibre material, the edges of the film are sealed airtight, a partial vacuum is created in the space between film and mould and the resin is admitted into said space in order to impregnate the fibre material. When the layers of fibre material are pressed apart, the film must therefore move with them. According to the invention this is achieved in that the film fitted is oversize such that, during foaming, the film can move over the required distance with the sheets of fibre material when these are pushed apart. If a stretchable film is used with this procedure, a regular, smooth surface is obtained after curing of the foamed resin.
It is also known to produce a product moulded on two surfaces by moulding the product in a mould space enclosed by two mould halves. According to the invention, a layered product with a foam core can now also be moulded on two surfaces in that the upper layer of fibre material is pressed upwards until it lies against the upper mould half. With this method the mould halves can have different shapes. With this method any differences in thickness in the product are compensated for by the uniform distribution of the resin foam forming between the layers of fibre material which are pressed apart. It is therefore simple to mould products with a fluctuating stiffness, for example with weakening zones in the form of regions with a smaller thickness, or of reinforcing zones in the form of ribs. In general, with this type of mould halves of different shapes one will possess a greater length in cross-section along the mould surface than the other. In this case, the lower mould half is preferably that having the smallest length in cross- section. Consequently it is relatively flat, which makes it easier to lay the layers of fibre material.
According to the invention, an article with differently moulded surfaces can now also be produced in that the upper layer of fibre material is inserted pleated, such that where the upper profile has a greater length than the lower profile there is a pleat in the uppermost fibre layer with an oversize of material relative to the lower fibre layer such that after the uppermost fibre layer has been pushed upwards this lies without pleats against the upper profile.
The foaming must take place directly after the impregnation as otherwise the resin would no longer be sufficiently fluid to push the layers of fibre material apart.
According to the invention the procedure is that the resin is injected as a mixture with foaming agent.
It is, however, also conceivable that before impregnation a resin without foaming agent is first introduced and then a resin with foaming agent is introduced. The two resins can differ or can be identical. For example, epoxy resin can be used for the outside and a hard polyurethane resin for the core.
The invention will now be described further with the aid of -several illustrative embodiments.
Fig. 1 shows a mould during a first phase of the method. Fig. 2 shows the mould of Fig. 1 during a second phase. Fig. 3 shows the mould of Fig. 1 during a third phase.
Fig. 4 shows a second mould for carrying out the method according to the invention, before foaming.
Fig. 5 shows the mould of Fig. 4, after foaming. The mould shown in Fig. 1 consists of a lower half 1 and an upper half 2. A number of layers of fibre material 3 have been laid in the lower half 1 and covered by a film 4. The edges of the film 4 have been clamped between the edges of the mould halves 1 and 2 so as to provide a seal. A partial vacuum is applied to the space between the film 4 and the mould half 1 via the connection 5, after which resin is injected via the connection 6.
Fig. 2 shows how the front 7 of resin spreads through the package of fibre layers 3. When the entire package has been impregnated, a foaming agent is injected via the injection point 8 into the resin between the layers of fibre material.
As shown in Fig. 3, as a consequence of this the uppermost layer of fibre material 3, together with the film 4, is pressed upwards against the upper half 2 of the mould. During this operation the air above the film 4 can escape via the vent 9. By virtue of the oversize material at the edges of the film 4, this can follow the upwards movement without problems. The layer of resin in foam form which is formed is indicated by 14. Fig. 4 shows a second mould in which the shape of the upper half of the mould deviates from that of the lower half. At the location of each recess 10 in the upper half 2 of the mould both the film 4 and the uppermost layer of fibre material 3 are provided with a pleat 11 and 12 respectively. By this means the shape shown in Fig. 5 can be obtained on foaming, the projections 13 being formed at the location of each recess 10 by the pleats 11, 12. After foaming, the film 4 and the uppermost layer of fibre material 3 lie smoothly against the upper half 2 of the mould.

Claims

Claims
1. Method for the production of fibre-reinforced articles, with which method a number of layers of fibre material are introduced into a mould and impregnated with resin and the resin is cured, characterized in that after impregnation but before curing, the volume of the resin is increased, the fibre layer or layers being pushed away towards the outside of the resin body.
2. Method according to Claim 1, in which at least two layers of fibre material are used, characterized in that the volume of the resin between the layers is increased.
3. Method according to Claim 1 or 2, characterized in that the volume of the resin is increased by foaming the resin, the viscosity and surface tension of the resin and the porosity of the fibre material being such that the layers impregnated with resin cannot be penetrated by the foaming resin.
4. Method according to Claim 1 or 2, characterized in that the volume of the resin is increased by feeding a resin filled with a filler between the layers of fibre material.
5. Method according to Claim 4, characterized in that the filler consists of small hollow or expandable spheres.
6. Method according to one of the preceding claims, characterized in that the resin is mixed with short fibres.
7. Method according to one of the preceding claims- characterized in that the resin is mixed with elastomeric particles.
8. Method according to one of the preceding claims, in which an airtight film is fitted on the package consisting of the layers of fibre material, the edges of the film are sealed airtight, a partial vacuum is created in the space between film and mould and the resin is admitted into said space in order to impregnate the fibre material, characterized in that the film fitted is oversize such that, during the increase in the volume of the resin, the film can move over the required distance with the layers of fibre material when these are pushed apart.
9. Method according to one of the preceding claims, in which the layers of fibre material are placed in a closed mould space between two mould halves, characterized in that the upper layer of fibre material is pressed upwards until it lies against the upper mould half.
10. Method according to one of Claims 1 to 7 inclusive, in which, in cross-section, the upper mould half has a profile with a greater
'5 length, measured along the mould surface, than the lower mould half, characterized in that the upper layer of fibre material is inserted pleated, such that where the upper profile has a greater length than the lower profile there is a pleat in the uppermost fibre layer with an oversize of material relative to the lower 0 fibre layer such that after the uppermost fibre layer has been pushed upwards this lies without pleats against the upper profile.
11. Method according to one of the preceding claims, characterized in that the resin is injected as a mixture with foaming agent. 5 12. Method according to one of the preceding claims, characterized in that a resin without foaming agent is first of all introduced and then a resin with foaming agent is introduced.
PCT/NL1989/000034 1988-05-11 1989-05-10 Method for moulding of fibre-reinforced articles WO1989010833A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8801244 1988-05-11
NL8801244A NL8801244A (en) 1988-05-11 1988-05-11 METHOD FOR FORMING FIBER REINFORCED ARTICLES

Publications (1)

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WO1989010833A1 true WO1989010833A1 (en) 1989-11-16

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB840394A (en) * 1957-06-26 1960-07-06 Standard Pressed Steel Co A method of moulding a double-walled structure such as a refrigerator door
DE1147029B (en) * 1958-06-04 1963-04-11 Bayer Ag Process for the production of plastic composite bodies
FR2187526A1 (en) * 1972-06-14 1974-01-18 Gall Gilles K Composite mouldings of resins and textiles - made by lining a mould cavity with a permeable textile or mat
EP0001442A1 (en) * 1977-10-01 1979-04-18 Bayer Ag Method for filling sandwich elements with a foam of reaction mixtures
EP0007431A1 (en) * 1978-06-24 1980-02-06 Schock & Co. GmbH Profile member, especially for the production of window frames, and process for the manufacture of this profiile member
US4250136A (en) * 1979-10-22 1981-02-10 Composite Technology Corporation Method of forming a composite structure
US4379103A (en) * 1980-08-25 1983-04-05 Detroit Gasket & Manufacturing Co. Method of forming a foam resin core structure having a smooth composite reinforced integral skin
US4510105A (en) * 1982-08-19 1985-04-09 Kent Sherwood Method of manufacturing a surface-reinforced foam article
EP0177736A2 (en) * 1984-09-11 1986-04-16 Mitsubishi Jukogyo Kabushiki Kaisha Fiber reinforced plastic product and method of forming products

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB840394A (en) * 1957-06-26 1960-07-06 Standard Pressed Steel Co A method of moulding a double-walled structure such as a refrigerator door
DE1147029B (en) * 1958-06-04 1963-04-11 Bayer Ag Process for the production of plastic composite bodies
FR2187526A1 (en) * 1972-06-14 1974-01-18 Gall Gilles K Composite mouldings of resins and textiles - made by lining a mould cavity with a permeable textile or mat
EP0001442A1 (en) * 1977-10-01 1979-04-18 Bayer Ag Method for filling sandwich elements with a foam of reaction mixtures
EP0007431A1 (en) * 1978-06-24 1980-02-06 Schock & Co. GmbH Profile member, especially for the production of window frames, and process for the manufacture of this profiile member
US4250136A (en) * 1979-10-22 1981-02-10 Composite Technology Corporation Method of forming a composite structure
US4379103A (en) * 1980-08-25 1983-04-05 Detroit Gasket & Manufacturing Co. Method of forming a foam resin core structure having a smooth composite reinforced integral skin
US4510105A (en) * 1982-08-19 1985-04-09 Kent Sherwood Method of manufacturing a surface-reinforced foam article
EP0177736A2 (en) * 1984-09-11 1986-04-16 Mitsubishi Jukogyo Kabushiki Kaisha Fiber reinforced plastic product and method of forming products

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Composites, volume 26, no. 3, June 1986, (Paris, FR) M. Delzant: "Contribution à l'étude du comportement des composites chargés de microsphères pleines ou Creuses en verre ou avec renfort hybride fibres-sphères", pages 203-213 *

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Publication number Publication date
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