SE420991B - KIT FOR PREPARATION OF FORMULA OF GLASS FIBER ARMED HARDWARE - Google Patents

Description

15 20 25 50 55 7801615-1 2 When manufacturing objects of reinforced thermosetting plastic in molds, which consist of mold parts, which can be closed so that a closed mold is formed, problems caused by open single molds are avoided. The fiberglass material is then placed. in the dry state in the closable, form. When injecting the plastic into the mold or when injecting the plastic with the aid of a vacuum cleaner, the plastic is supplied after the tube with the fiberglass material applied therein has been closed. When pressing the object, the plastic is poured on. the glass fiber material when it is applied in the lower mold half of the mold, after which the upper mold half is pressed down against the lower mold half to form a closed mold ridge, in which the plastic impregnates: the glass fiber material. The glass fiber material can, among other things, consist of a preform of chopper: glass fiber. The glass fiber is then preformed to the shape the amering should have when it fills the foam cavity and is held together with an adhesive so that the preform can be applied in the foam cavity.

Preforming according to known methods is done as follows. that a net shape, usually of perforated pm, which 1 has a small design like the five mashed plastic part, is placed over the suction opening of a powerful centrifugal fan. The fan sucks with large capacity air through the holes in the net shape. Fiberglass roving is cut to the lcmlppen with a chopping block and may fall down against the net form or be blown with one. blowing device against the net shape. Through the powerful. negative pressure generated under the mesh shape of the fan, the cut fiber is sucked against the mesh shape and forms a blanket.

To get so. even distribution of the fiber as possible, the negative pressure must be. large. A binder is powdered or sprayed on. meanwhile the fiberglass accumulates on the mesh form. Polyester powder or a polyester ester emulsion is usually used as a binder. The polyester is then provided with a harder. Solutions of polyester in, for example, ethyl acetate, alcohol or acetone were also used in practice. Then fiberglass and binder collected. the mesh is dried and the binder is normally cured. The net shape is then placed. in a protection zone or oven, still with the fan sucking fiberglass and binder fixed to the mesh surface. It is essential that the fiberglass bundles are tightly bound to each other so. that they do not accompany the plastic in its flow: The shape in connection with the shaping of the eroded object and thus gives rise to an uneven distribution of the glass fibers in the finished object. Preforming of the glass fiber material is common in the production of small and medium-sized objects by hot pressing. The process time is short.

The pre-processing process requires large investments, especially due to the required, substantial. the fans, and the operating costs (are high. The method is not suitable for the manufacture of large objects due to the then required large fan capacity for the preforms. Because it is the fan that directs! 10 15 20 25 30 55 7801615-1 the glass fiber to the preforming mold different parts there is the big problem a few .the same amount of fiberglass at t er corners and edges as on less curved surfaces ..

It is also difficult to provide preforms with intentionally different thicknesses of the glass fiber layer at different locations.

The present invention relates to a method of manufacturing glass fiber reinforced plastic articles using a forming method which requires a simple equipment and which allows practically unlimited possibility of directing the glass fiber to desired portions of the preform so. that the fiberglass layer can be given an intended thickness everywhere and regardless of the shape and size of the mold.

The preforming can be performed without the use of environmentally harmful substances. Then. the shaping of the reinforced object also takes place with closed. molding methods, the invention assumes the advantages from an environmental point of view as such. methods have. In order for the properties of the finished article to be at least equivalent to those of an article made by spraying, a binder in the preform which has time to dissolve in the plastic is preferably used before it cures.

More particularly, the present invention relates to a method of making articles of fiberglass-reinforced thermosetting plastic, wherein a preform of chopped fiberglass having substantially the same. shape in which the object is made by distributing the glass fiber and a binder for the glaze fiber. the surface of a preform and the one produced. the preform is placed in a closable mold space in a mold for the molding of the object and the plastic in the uncured state is added to the mold space and then brought to hard, characterized cloat thereof, that the preform is produced by feeding chopped fiberglass a jet of finely divided liquid containing a binder for the glass fiber and the beam with its content of 'glass fiber and binder is directed towards different parts of the surface of the preform. until a required amount of fiberglass has been built up. the surface and that the preform of the glass fiber held together with the binder is placed in the mold and the plastic in an uncured state is supplied. In the particularly preferred embodiment, a binder soluble in the uncured plastic is used and the binder is 'maintained' in soluble form when the preform is placed in the mold space and the plastic is applied in the uncured state.

The method according to the invention is particularly suitable for use in the production of reinforced objects in which. the plastic is injected or sucked in with a vacuum in the closed area. the mold cavity or the preform is applied before closing the mold run, followed in the latter case by a pressing, and especially then in such. cases where the shaping of the object shoes using sv low. pressure and low temperature such as room temperature or moderately elevated temperature. 7 151615-1 7801615-1 e, p, In order to produce the preform, conventional spraying devices of the types used in the spraying of plastic and fiberglass can be used. By transporting the glass fiber elements to the preform of the atomized liquid jet and the jet can be directed towards any portion. the preforms found, the desired thickness of the glass fiber layer can be achieved in each part of the preform.

The preform is suitably made of a material with through holes, for example of a net of metal or plastic, such as pve, or of perforated sheet metal. An advantageous design of the mold has been found to be an open fiberglass fabric which has been impregnated with plastic and which, after excess plastic has been allowed to drain off, is placed in a mold and hardened. According to the present invention, it may also be appropriate in some cases to place the preform on a sole to accelerate the evaporation of the liquid and to retain the sprayed fiber on. vertical. surfaces on. the preform. For such tasks, however, a substantially lower fan capacity is required than in conventional preforming, where the fiber distribution, in contrast to what is the case according to the present invention, is controlled by the fan.

As a liquid in the jet, water is preferred for environmental and fire risk reasons. As such, however, it would be possible to use other solvent-type liquids such as ethanol and methanol.

It has been found that the liquid with binder must have * a low viscosity to give satisfactory bonding and a low dry matter content in order to be able to spray: glass fiber is constantly built up on the preform without leaving too much binder content in the finished preform after drying. . The viscosity is preferably at 1-10 centipois and the dry matter content is preferably at 5-20% by weight. The binder belt in the finished preform, i.e. when the liquid has evaporated, is preferably at 3-15 7% of the total weight of binder and fiberglass in the preform.

According to a preferred embodiment of the present invention, the solubility of the binder in the plastic is such that the binder holds the glass fiber on a plate in the mold, when the plastic in the uncured state is added to the mold and distributed in the glass fiber and that the binder is at least substantially dissolved in the plastic. the curing of the resin starts. By holding the glass fiber in place until it is distributed in the preform, the formation of portions with a low glass fiber content and veo formation in the object is avoided. Because the adhesive is dissolved in the plastic when the curing starts, a binder film is avoided. the glafiber 10 15 20 25 30 7801615-1 prevents direct contact between plastic and fiberglass and as a result the mechanical properties of the object deteriorate.

As an example of. Suitable binders include polyvirxylacetate, alkali metal epoxy acrylate and styrene and urethane plastics. The exemplified agents are soluble, emulsifiable or suspensible in water.

It has proved advantageous in some cases to use a mixture of at least two binders with different solubilities, one having a short solubility time and one having a longer solubility time in the one used. plastic. By varying the amounts of the binders, however, the solubility time of the mixture can be affected and thus adapt it to the shape and thickness of the material used.

The plastic is preferably an unsaturated ester plastic thereof. types conventionally used in the manufacture of glass fiber reinforced plastics. Its unsaturated monomer is preferably styrene, methyl metal acrylate or vinyl toluene.

The plastic lean too. consists of other solvent-free plastics such as epoxy plastics and urethane plastics.

The invention will be explained in more detail by describing an exemplary embodiment with reference to the accompanying drawing, in which Fig. 1 shows a device for manufacturing a preform according to the present invention, Fig. 2 and Fig. 3 details in Fig. 1 on a larger scale and Fig. 4 a device for producing a reinforced object of the preform according to Fig. 1.

According to Fig. 1, a atomized jet 1 of water containing a binder is generated in a syringe assembly consisting of a pressure vessel 2 or of a pump with a line 5 to a gun 4. The line 3 is so flexible. that the gun can stir and rotate in arbitrary directions. The munetyoke of the pistol is provided with a slot 5 (Fig. 2) and Sa, respectively. and oh (Fig. 5) which affects the shape of the beam.

In the embodiment shown in Fig. 2, the slot 5 is horizontal and gives a substantially horizontal beam 1. In the embodiment shown in Fig. 5, two are used. pistols 4a and 4b with slots See. respectively 51: »which form oblique. works with the horizontal plane and as in theirs. extensions downwards form an oblique angle with each other. In this case, a beam 1 with a V-shaped cross section is obtained. The jet consists of water containing 8% by weight of polyvinyl acetate.

Glass fiber in the form of roving 6 with a thickness of 2400 g per km and with a diameter of 10 .mu.m of the individual sparse fiber is fed from a storage mill 7 to a chopping tool B. The chopping plant consists of a smooth rubber mill 9 and a with knives "" n7so1s1s-1 10 15 20 25 50 55 40 6 10 fitted metal roller 11, where the roving is cut to about 5 cm long. bundles 12, as vie. a sloping table 13 may fall into the beam 1. The beam transports The fiber is then permeable to gas and liquid, and is made of a glass fiber fabric, which is impregnated with an unsaturated ester plastic and cured after excess resin has been drained off, leaving openings 15 at the meshes. The mold 14 is placed on a funnel-like table 16, in which a low capacity fan 17 is provided to facilitate the escape of water from the layer of fiberglass formed on the mold 14 and to help retain sprayed fiber on vertical surfaces. on .form.Then form 14 on. all surfaces are provided with a fibrous layer of the desired thickness, the process is interrupted amt the preform 18 is dried, so. that the water is removed.

The preform is then applied in the form in which the final object is to be manufactured. An example of such a manufacture, injection molding of the plastic, is illustrated in Fig. 4. The mold of Fig. 4 has two. mold parts the two mold halves 21 and 22, which between them form the mold rim 25 and which are held in a certain position relative to each other with the spacer styok 24. The mold parts are kept pressed against each other with a clamping device (not shown). The shape can be. made of eg fiberglass-reinforced plastic, aluminum or steel. Prior to the joining of the mold parts 21 and 22, the previously described preform 18 has been placed in the mold. The edges of the preform protrude into the compression gap 26 and are clamped there between the front parts 21 and 22. The thickness of the gap 26 is adapted accordingly. that it lets air through from the mold run but not or only to a small extent plastic in the uncured state. The upper mold part is provided with an inlet 27 for unhardened plastic.

The part of the inlet closest to the mold space is formed as a valve, consisting of the valve seat 28 and the loose valve opening 29 of polypropylene. The plastic, which in the exemplified case consists of an unsaturated ester plastic with styrene as monomer (eg Crystic 2230 from AB Syntes, Sweden), is supplied by being pressed in with an injection gun 30 ,, The content of styrene in the ester plastic amounts to 35 7% by weight ester plastic including styrene. The plastic is mixed in the gun immediately before its injection by mixing plastic containing catalyst, eg 1% by weight of benzoyl peroxide, from line 31 with plastic of the same type containing aocelerator, eg 0.05% by weight dimethylparatoluidine, from line 52. After the plastic has been injected, the out moldmnxmet ooh is distributed in the preforms 18 at the same time as air is forced out into the gap 26. So. as soon as the plastic has reached the gap 26, which when using a low-viscosity plastic can take only a few minutes, the plastic supply x is interrupted by switching off the gun. During this. process, the binder effectively holds the fiberglass lozipps in the preform in place. During

Claims (2)

1. 0 7801615-1: The injection body is pushed downwards by the plastic so that a gap 33 is maintained between the valve seat 28 and the valve mop 29. When the injection is interrupted, the valve body is automatically pushed upwards by the pressure of the plastic in the foam chamber 23 and closes inloppet. When the plastic starts to harden after about 10 minutes, all the binder is dissolved. After chlorination for 50 minutes, curing is complete. The finished article is then removed from the mold and the edges are cut off at 56. The mold parts may contain. built-in, pipe loops 37; Boom can be used for cooling if the mold gets too hot. due to an exothermic curing reaction of the plastic or for a certain deterioration of the mold before the exothermic reaction keeps it at the desired temperature, for example slightly above room temperature. PATEEIT REQUIREMENTS 1. A method for producing articles of fiberglass-reinforced hardening plate, wherein a preform of the bug glass fiber having a substantially sanzma shape on which the object is made is distributed by gleefibre and a binder for the glass fiber. the surface of a preform mold and the produced preform are placed in a closable mold space in a mold for molding the article and the plastic in the uncured state adjoins the mold cavity and then caused to cure, characterized in that the preform is produced by the bug fiberglass is supplied to a jet of atomized 'liquid / containing' a binder for the glaze fiber, and the jet with its: fiberglass content and binder is directed towards different parts of the preform surface until a required amount of fiberglass is built up on the surface and the preform is removed with Concentrated fiberglass is placed in the mold and the plastic in the uncured state is added. 2. A method according to claim 1, characterized in that a binder soluble in the uncured plastic is used and that the binder is maintained in soluble form when the preform is placed in the mold and the plastic is applied in the uncured state. 5. A method according to claim 1 or 2, characterized in that the liquid consists of water. LEADING PUBLICATIONS = Switzerland 553 642 (B29D 3 / oz)