WO1984002491A1

WO1984002491A1 - Arrangement comprising plastic ingredients and reinforcement

Info

Publication number: WO1984002491A1
Application number: PCT/SE1983/000453
Authority: WO
Inventors: Jan Christensen
Original assignee: Rovac Ab
Priority date: 1982-12-23
Filing date: 1983-12-14
Publication date: 1984-07-05
Also published as: ZA839492B; JPS60500284A; ES285338U; OA07785A; IL70501A0; IT1170064B; EP0134218A1; FI843318A0; FI843318A; IT8324381A0; EP0131015A1; IT1170063B; ES285338Y; NO842890L; WO1984002490A1; KR840006930A; JPS60500440A; IT8324380A0

Abstract

An arrangement or a semi-manufactured item comprises plastic ingredients (6) and reinforcement contained inside a tightly sealed plastic film cover (5). Said ingredients consist of a based material contained inside the cover in a moisture-proof fashion together with the appropriate initiator and activator for polymerization to nylon-6 or nylon-6 copolymers. Polymerization is capable of being initiated at a temperature considerably above the temperature or the temperatures achieved during the manufacture and storage of the arrangement.

Description

TITLE OF THE INVENTION

Arrangement comprising plastic ingredients and reinforcement.

TECHNICAL FIELD

The present invention relates to an arrangement comprising plastic ingredients and reinforcement enclosed inside a tightly sealed plastic film cover in which the ingredients are intended to assume a de-activated condition, in which a chemical process for the transformation of the ingredients into a finished plastic material is not initiated, and an activated condition, in which the process is initiated.

DESCRIPTION OF THE PRIOR ART

Previously disclosed, for instance in European Patent Application 17452, is the method of enclosing plastic material containing a cure system which will commence to function as soon as initiation takes place via suitable initiation organs, whereby the intended curing process will be achieved.

DESCRIPTION OF THE PRESENT INVENTION

TECHNICAL PROBLEM

A number of advantages are achieved by enclosing plastic ingredients inside a tightly sealed plastic film cover. This will permit a centralized production of the environmentally harmful factors, more simple handling procedures than are required, for example, with SMC materials (Sheet Moulding Compounds) due, arongst other things, to the fact that the ingredients are packed in individual portions. The accurate weighing-out of the relative proportions of the plastic ingredients and minimal waste, etc. can be achieved. The need exists, however, in the case of this type of semi-manufactured item which is capable of being initiated into the activated condition with the help of heat, to be able to achieve a better distinction between the de-activated and the activated conditions of the arrangement so as to avoid the risk of accidental activation taking place. There is also a requirement for semi-manufactured items which remain stable during storage and which contain a high level of reinforcement in order to produce strong and durable finished products.

SOLUTION

The principal object of the present invention is to propose an arrangement which, amongst other things, will solve the problem outlined in the foregoing. What may essentially be regarded as the characteristic feature of the novel arrangement is that the plastic ingredients consist of a base material contained inside the plastic film cover in a moisture-proof fashion together with the appropriate initiator and activator for polymerization to nylon-6 or nylon-6 copolymers, whereby polymerization is capable of being initiated only at a temperature, for instance of about 150ºC, which is considerably higher than the temperature or the temperatures achieved during the manufacture and storage of the arrangement.

In further developments of the idea of invention it is proposed that the reinforcement, preferably being glass fibre reinforcement, shall comprise long fibres and/or one or more continuous and possibly braided fibre mats (roving). The reinforcement should then preferably account for about 30 per cent by weight of the total weight of the arrangement. The arrangement should preferably also be of relatively thin execution, for example 1-3 mm in thickness.

In one preferred embodiment the plastic film cover is made of nylon. In a second preferred embodiment the cover is made of polyolefine, polyester or fluorinated vinyl polymer. The plastic film is comparatively thin, preferably between 0.02 and 0.2 mm in thickness.

The base material is also metered in order to compensate for shrinkage due to polymerization.

Other further developments of the idea of invention are concerned more with the structure of the arrangement. Thus, in a preferred embodiment, the composition of the ingredients of the unit, the geometrical position of the ingredients inside the unit and the external form of the unit must be determined with great accuracy in the course of the manufacture of the unit, which may be achieved by the use of a computer-controlled production process. The plastic cover may be part of or may be separated from the unit when it is activated or transformed into a finished product. The unit may be executed with internal walls or with internal pockets and/or may be provided with an inner unit which, for the purpose of separation, encloses those ingredients which are to form part of said chemical process when the unit is activated.

ADVANTAGES

The proposed arrangement provides advantages, amongst other things in the area of manufacture. The base material is liquid at temperatures in excess of 69ºC, and polymerization will only occur at a temperature of about 140ºC. The base material may be brought during manufacture to a temperature, for instance of about 70-75ºC, which is not critical from the point of view of polymerization. At said temperature a glass fibre mat, for example, may be dipped into or sprayed with the base material containing an initiator and an activator. At ambient temperature (20-25°C) the material will have solidified, and an essentially dry and rigid filling can then be enclosed by the thin plastic film cover. Transport and storage are simplified in this way. The proposed arrangement also enables a finished product to be produced in nylon-6 or nylon-6 copolymers with long fibres (glass fibre) or continuous and possibly braided fibre mats (in glass). Until now it has been possible to execute the reinforcement in nylon-6 products only in the form of millimetre-thick glass fibres.

Moisture-proof enclosure can be provided with the help of a vacuum chamber inside which the humidity level is kept down by the use of low pressure, for example 0.1-0.3 bar. Enclosure can also make use of an inert gas (nitrogen gas), if necessary in combination with the use of a vacuum chamber.

The finished product is then conditioned in order to produce increased tenacity (toughness) in the material.

If so desired, a very advantageous external structure can be achieved which does not require any further processing, for example in the form of grinding, washing and/or cleaning, but which may be painted or finished in some other way directly. The characteristics built into the unit in the course of its manufacture mean that it can be stored for lengthy periods (in some cases for a number of months).

In the event of manufacture taking place inside a vacuum chamber a very high degree of freedom from air bubbles will be achieved in the finished product, which offers particular advantages in the area of, amongst other things, the manufacture of components which will subsequently be subjected to surface treatment, for example painting at high temperature, when air bubbles would otherwise appear and cause local porosity in the material.

The foregoing also means that components which previously had to be produced from sheet and metal, for example within the automobile and marine industries, can now be produced either entirely or in part from plastics. This also means that much of the rust problem encountered, for instance, within the automobile industry can now be resolved, and that the noise level associated with the production of such components can be reduced.

DESCRIPTION OF THE DRAWINGS

Preferred embodiments of an arrangement in accordance with the invention are described below with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view seen from above and from the right of a first arrangement or a semi-manufactured item, and of an identical arrangement joined to said first arrangement and illustrated in part only;

Figures 2a-2b show respectively a horizontal and a side view of a second arrangement;

Figure 3 shows in vertical longitudinal section a low-pressure chamber inside which the production of a semi-manufactured item can take place; and

Figures 4a-4b show in diagrammatic form the underlying principle of a production line for a third arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Figure 1 shows two arrangements or units 1 and 2 applied to a base U , said arrangements or units being joined together by means of a connecting piece 3 and 4 along one edge of each unit. The units may also be separate or connected to other units. Each unit is represented as a polygon, in particular as a square or rectangular unit having a length L , a width 8 and a thickness H . The thickness is selected so as to permit thin finished products to be produced having a thickness preferably of between 0.5 and 5.0 mm, and in particular of between 1 and 3 mm. The unit may, however, be tailor-made (pre-moulded) for each particular application and may accordingly exhibit other shapes depending on the intended application.

Each unit comprises a thin (e.g. 0.02 - 0.2 mm) cover of plastic material, referred to here as a plastic film cover 5 , and ingredients 6 contained inside the plastic cover and so arranged that, with the unit in its storage or transport position, they do not take part in a mutual chemical reaction for the purpose of producing a finished plastic material, and that, with the unit in an activation and utilization position initiated by means of an activation process, they take part in said chemical reaction.

When viewed from the outside, each unit may be executed in a more or less rigid form depending, amongst other things, on the viscosity of the enclosed ingredients and on any reinforcement. The plastic cover 5 encloses the ingredients 6 in an essentially air-tight condition and, in the embodiment shown here, in an air-evacuated condition. The type of the plastic cover may vary depending on whether the cover is to be included as part of the finished plastics material or is to be used as a means of protection in, amongst other things, moulds which will possibly be used for the final moulding of and/or for combination with some other part of the unit. The cover which, as a general rule, will be wished to be flexible, may be selected from amongst the following groups of materials, for example: the polyolefins, the polyamides, the polyesters or the fluorinated vinyl polymers. The plastic cover is welded or is joined in some other fashion (e.g. by glueing) around its outside edges, of which 3, 3a and 3b are shown here. The plastic film must be capable of being glued or welded and must as a rule be capable of being stretched and must exhibit low permeability by liquid ingredients. The plastic cover may in a typical embodiment be executed with barrier walls and pockets for the purpose of forming various spaces inside the unit. This will enable different ingredients to be kept separate inside the various spaces. On the aforementioned activation taking place, which may involve activation by compression, these walls will rupture, causing the ingredients to mix, and the chemical reaction can then be initiated by the supply of external heat. A barrier wall of this kind is indicated as a broken line by the reference designation 7 . The plastic cover itself may also be double, whereby the first (outer) plastic cover is given a first characteristic and the second (inner) plastic cover is given a second characteristic.

Each unit is a geometrical fit with, or can be made to fit the shape of the object or the addition to said object which the unit is to form. Figures 2a and 2b illustrate typical examples of the unit E which has been pre-moulded during manufacture so as to provide a good fit with the final shape of, for example, a chair. The edge E' may be welded or glued together in a previously disclosed manner using previously disclosed welding or glueing organs S . The quantity of material which the unit represents or includes is in itself sufficient to form the object or the addition. It will be necessary to waste only a small amount of material. The distribution of the ingredients inside the unit is provided (controlled) preferably at an optimum level in the course of manufacture, which is also true of the composition of the ingredients. It is possible in this way, for example, to place reinforcements A in their precise positions inside the unit, which is thus able to exhibit first parts (A') with a first ingredient composition and second parts D with a second ingredient composition. This is true both in the horizontal and in the vertical plane.

Figure 3 illustrates a more detailed example of the construction and manufacture of the unit. The unit should be produced in an essentially moisture-free environment preferably inside a chamber 8 at a pressure well below atmospheric pressure, e.g. about 10-30 kpa (0.1 - 0.3 bar) or below. The entrapment of moisture and air is eliminated to a very great extent in this way.

The unit in accordance with the invention will form a reinforced (glass fibre-reinforced) semi-manufactured product in nylon-6 or in a nylon-6 copolymer Onto a film 9 of nylon-6 or a similar material are laid one or more thin glass fibre mats prepared beforehand in an appropriate manner. Said mat or mats are impregnated with monomer/monomers, an initiator and an activator for the polymerization reaction. Before impregnation takes place, the materials are heated to bring them to a suitable viscosity, for example to a temperature of 70-75ºC. Impregnation may then take place by spraying, for example by means of the sprayer organ 12 , or by dipping. Once the glass fibre mat has been coated with the aforementioned ingredients it is cooled, causing the coated material to solidify, thereby producing a relatively dry and rigid, impregnated glass fibre mat. It is, of course, possible to build up in accordance with the above several layers of the impregnated glass fibre mat. Similarly, the impregnation of the fibre-glass fabric or the glass fibre mat may take place before the preparation operation.

Once the desired number of glass fibre mats has been laid-up and impregnated, a film 13 of nylon-6 (in accordance with the above) is laid on top. Said upper and lower sheets 9, 13 are then joined together, either by welding or by glueing, so as to form a tightly sealed cover. The welding organs and/or the glueing organs 14a, 14b and 15a, 15b may be executed from previously disclosed elements and are so arranged as to be capable of being moved around the peripheral edge of each semi-manufactured item. The organs 14a, 14b and 15a, 15b are also capable of being moved in other directions towards and away from each other. A base for the film 9 is indicated by the reference designation 16 and clamping organs for the films are indicated by the reference designations 17a, 17b and 18a, 18b . The film 13 is capable of being unrolled over the finished laminate by means of an organ 19 , for example an unrolling organ capable of being moved over the laminate. The flow of material leaving the application organ 12 is indicated by the reference designation 20 . The end 13 of the film is shown by means of a broken line. The chamber is provided with air evacuation equipment 21 and 22 which also incorporates air de-humidification organs 21a, 22a and temperature-controlling equipment 21b and 22b of a previously disclosed kind. The parts of the equipment 21 and 22 are joined together via a line 23 which extends through the wall of the chamber 8 . Material containers 24 for the base material and for the initiator and the activator are connected via the line 25 . The organ 12 can be controlled by a robot 26 in a previously disclosed fashion in various directions 27a, 27b . Fibre mats 10, 11 and film 9, 13 can be introduced via a door 8a in the chamber. By arranging for the enclosure operation to take place under high negative pressure, the finished material can be made to contain only very small quantities of entrapped gas, for example not more than of the order of 0.5 per cent by volume, and for example 0.2-0.3 per cent by volume of the total volume of the unit. The chamber is able, as an alternative to the moisture-free enclosure environment, to form by means of negative pressure and the air evacuation organ an enclosure environment containing an inert gas, for example nitrogen gas, which eliminates the problems associated with entrapped moisture. The equipment 21,22 may, either as an alternative or in addition, incorporate organs 21c, 22c to guarantee the supply of the nitrogen environment into the chamber.

Since the selected materials are not subjected at any stage during manufacture to a temperature sufficiently high to initiate the polymerization reaction, the risk of the premature polymerization or activation of the unit is eliminated. The initial temperature at which said polymerization will usually begin is about 130-150°C.

Polymerization will start, therefore, when the unit and its contents are heated to the temperature referred to above. The unit is easily moulded into a product, since all the materials apart from the glass fibre mat become liquid at temperatures in excess of 69°C.

The expression monomer used in connection with nylon-6 shall be understood to denote ε-caprolactam in this context. The expression initiator denotes a compound from one of the following groups: the alkali metals; the alkali earth metals; the oxides, hydrides or alcolates of the last-mentioned metals; or their compounds with the lactams, in this case sodium caprolactamate. The expression activator is used in this context to dunote an acylating compound, in this case a prepolymer isocyanate.

When metering the quantities of said ingredients supplied to the unit (impregnation of the glass fibre mat) allowance must be made for the shrinkage which occurs during the polymerization reaction. The pre-forming of the unit into a finished product or an addition may take place at low pressure in a simple mould. One requirement associated with this is that the mould shall be capable of being heated to the temperature at which the polymerization reaction will start and will continue in a satisfactory manner, in this case about 140ºC. Heatable moulds of this kind have already been disclosed and do not, therefore, require to be discussed in any more detail here.

When using nylon-6 copolymers, use may be made of the complete systems which are generally available on the market, for example a system marketed by Monsanto under the name Nyrim 2025 MG.

The unit may, in accordance with Figures 4a-4d, also be used in the production of a semi-manufactured item, for example for a door with windows. A sheet 28 of nylon-6 (Capran ER 20) is vacuum-formed to the appropriate initial dimensions of a semi-manufactured blank for a door 29 , the outline for the window of which is indicated by the reference designation 30 . This operation may be performed at a first station. The reinforcement material 31 which has been given a shape corresponding to the shape of the door is applied to the vacuum-formed sheet at a second station. The pre-forming of the reinforcements 31 may be done separately by means of stamping or by layer cutting or by some other previously disclosed method. Hoses 32, 33 or similar are applied to the components in question at a third station. A covering sheet 48' of the same nature as the bottom sheet is then positioned over the components and the hoses 32, 33 . The top and bottom sheets are then welded or glued along their edges 39 . The sheets are then stamped or cut in such a way that the unit in accordance with Figure 4c is produced. The hose 33 is then connected to a vacuum pump 34 and the hose 32 is connected to a connector unit 35 for a nylon monomer containing an initiator and an activator. Once the unit 36 has been filled with the monomer/monomers in question, the hoses 32, 33 are sealed, for example by welding, so that the cover formed by the top and the bottom sheets encloses the ingredients contained therein under essentially moisture-proof and, if necessary, air-evacuated conditions.

The sheet may simply be caused to weld together with the laminate contained inside it by raising the temperature during hardening to 200-220ºC. In order to prevent adhesion in the mould in this case, double sheets may be used, whereby the outer sheet shall exhibit a melting temperature in excess of the last-mentioned temperature. The proportion of the reinforcement present may assume values of up to about 30 per cent by weight. As an alternative to or in addition to said continuous fibre mats, use may be made of long fibres, for example of glass, of about 25 cm in length or longer. The arrangement or the semi-manufactured item may be given a lengthy storage capacity, for example several months, enabling the arrangement or the semi-manufactured item to be stored and handled under ordinary ambient temperature conditions. Finish-formed plastic material is conditioned so as to produce a certain amount of toughness in the material. The present invention is not restricted to the embodiments specified above by way of example, but may undergo modifications within the context of the following Patent Claims and the idea of invention.

Claims

PATENT CLAIMS

1. Arrangement comprising plastic ingredients (6) and reinforcement (10, 11) contained inside a tightly sealed plastic film cover (9, 13) in which the ingredients are intended to adopt a de-activated condition, in which a chemical process for transforming the ingredients into a finished plastic material is not initiated, and an activated condition, in which the process is initiated, c h a r a c t e r i z e d in that the plastic ingredients consist of a base material (20) contained inside the plastic film cover in a moisture-proof fashion together with the appropriate initiator and activator for the polymerization of nylon-6 or nylon-6 copolymers, whereby polymerization is capable of being initiated only at a temperature, for instance of about 130-150ºC, which is considerably higher than the temperature or the temperatures achieved during the manufacture and storage of the arrangement.

2. Arrangement in accordance with Patent Claim 1, c h a r a c t e r i z e d in that the reinforcement, preferably being of glass, comprises long fibres, for instance fibres of at least 25 mm in length.

3. Arrangement in accordance with Patent Claim 1 or 2, c h a r a c t e r i z e d in that the reinforcement, preferably being of glass, comprises one or more continuous and possibly braided fibre-glass mats.

4. . Arrangement in accordance with Patent Claim 1, 2 or 3, c h a r a c t e r i z e d in that the reinforcement accounts for about 30 per cent by weight of the total weight of the arrangement.

5. Arrangement in accordance with any of the preceeding Patent Claims, c h a r a c t e r i z e d in that together with its reinforcement it is sufficiently thin to permit a material thickness for a finished product which is between 0.5 and 5.0 mm in thickness, and preferably 1-3 mm in thickness.

6. Arrangement in accordance with Patent Claim 1, c h a r a c t e r i z e d in that the plastic film cover is executed in nylon and is preferably between 0.02 and 0.2 mm in thickness.

7. Arrangement in accordance with Patent Claim 1, c h a r a c t e r i z e d in that the plastic film cover is executed in polyolefine, polyester and/or fluoriπated vinyl polymer and is preferably between 0.02 and 0.2 mm in thickness.

8. Arrangement in accordance with any of the preceeding Patent Claims, c h a r a c t e r i z e d in that the base material is metered in order to compensate for shrinkage due to polymerization.