NL1019320C2 - Formation of thin-walled products from plastic mold comprises introducing heated plastic in mold cavity while mold is partly open, and pressing away plastic in mold cavity by wall parts of mold cavity - Google Patents

Formation of thin-walled products from plastic mold comprises introducing heated plastic in mold cavity while mold is partly open, and pressing away plastic in mold cavity by wall parts of mold cavity Download PDF

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Publication number
NL1019320C2
NL1019320C2 NL1019320A NL1019320A NL1019320C2 NL 1019320 C2 NL1019320 C2 NL 1019320C2 NL 1019320 A NL1019320 A NL 1019320A NL 1019320 A NL1019320 A NL 1019320A NL 1019320 C2 NL1019320 C2 NL 1019320C2
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NL
Netherlands
Prior art keywords
mold
plastic
mold cavity
product
part
Prior art date
Application number
NL1019320A
Other languages
Dutch (nl)
Inventor
Hendricus Antonius Hoogland
Original Assignee
Novem Internat B V
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Publication date
Application filed by Novem Internat B V filed Critical Novem Internat B V
Priority to NL1019320A priority Critical patent/NL1019320C2/en
Priority to NL1019320 priority
Priority claimed from CNB028261062A external-priority patent/CN100522552C/en
Application granted granted Critical
Publication of NL1019320C2 publication Critical patent/NL1019320C2/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14778Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles the article consisting of a material with particular properties, e.g. porous, brittle
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/46Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/56Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
    • B29C45/561Injection-compression moulding
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C2045/0096Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor drying the moulding material before injection, e.g. by heating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/46Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/56Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
    • B29C45/561Injection-compression moulding
    • B29C2045/563Enlarging the mould cavity during injection
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0017Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor moulding interconnected elements which are movable with respect to one another, e.g. chains or hinges
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/26Scrap or recycled material

Abstract

A method for forming thin walled products comprises introducing heated plastic (30) in mold cavity (10) while mold is partly open, and pressing away plastic in mold cavity (16) by wall parts of mold cavity after mold is closed so the plastic completely fills the mold. An Independent claim is also included for an apparatus for forming products comprising mold having mold cavity, mechanism for introducing plastic, and mechanism for closing the mold after plastic is introduced.

Description

Title: Method and device for forming thin-walled products and a product manufactured with them.

The invention relates to a method for forming thin-walled plastic products in a mold.

Thin-walled products are usually made from plastic by injection molding in a mold. Materials 5 with a relatively high Melt Flow Index (MFI), or at least a high melt, are used for this. Such a high MFI means that the plastic in liquid form has a low viscosity and can therefore travel relatively long flow paths with small dimensions in a mold cavity. The ratio between the length of a flow path and the minimum passage height of the flow path in question is usually referred to as the Melt Flow Rate (MFR). A high MFR therefore means a relatively long, narrow flow path. Injection molding is in principle possible with plastics with a high MFI, where there is a direct relationship between the MFI and the MFR. A higher MFR requires a higher MFI. It will be clear, therefore, that plastics with a low melt, at least a low MFI, cannot be injection molded, at least not in thin-walled plastic products. After all, thin-walled plastic products have an MFR that is too high for that. This means that from low-melt plastics only products are injection molded with relatively thick walls and relatively short flow paths.

Moreover, such methods require relatively high closing forces and a relatively long cycle time, which is economically disadvantageous.

An object of the invention is to provide a new method for molding plastic products into a mold.

A further object of the invention is to provide such a method with which products can be formed in a mold from plastics with a relatively low melt.

1019320 2

A further object of the invention is to provide a method with which products can be manufactured in a mold, made of plastic, wherein a relatively low closing force can be applied and a method with which relatively short cycle times can be achieved.

These and further objects are achieved with a method according to the invention.

In a method according to the invention, plastic is introduced into a mold cavity, the volume of the mold cavity slightly deviating from the volume of the product to be formed therein. Only when the quantity of plastic required for the formation of the product has been introduced into the mold cavity, is it brought into its final shape such that plastic is displaced and distributed through the entire mold cavity. The plastic can in principle be introduced under relatively low pressure, so that relatively low closing force will suffice. The resistance that the plastic encounters during insertion will be smaller than with injection molding of a product from the same plastic, if at all possible, in a conventional manner.

In a method according to the present invention, plastic products can be formed relatively quickly, that is to say at low cycle times, from all kinds of plastics, with relatively small wall thicknesses which, moreover, if desired, can differ relatively strongly in the product.

In a further embodiment of a method according to the invention, low-melt plastic is heated in a mold cavity, wherein the mold is at least partially opened. Without wishing to be bound by any theory, this appears to result in flow paths being obtained over a first part of the filling range of the mold with dimensions such that an MFR is obtained that matches the MFI of the plastic in question. During or after insertion of the plastic into the mold cavity, such that it is partially filled with the plastic, the mold is closed, at least the mold cavity is shaped into the mold corresponding to the desired end product, whereby the plastic is further placed in the mold cavity. pressed. Because the mold cavity is initially only partially filled, as a result of the fact that the total volume of the mold cavity with the mold open is larger than the final volume with the mold closed, a filling front is created. In this context, filling front is to be understood to mean the edge of plastic in the mold cavity in front of flow direction. The closure of the mold can in this case be regulated such that a flow path always lies directly in front of said filling front, the Melt Flow Rate of which fits approximately, is at least equal to or smaller than the MFI of the plastic in question. This means that it is always ensured that the plastic is displaced over the desired distance and therefore in a simple manner leads to complete filling of the mold cavity.

In a method according to the invention, a mold cavity is preferably used which, in a fully closed state, has a Melt Flow Rate from the or each injection point for the plastic that is higher, in particular much higher, than the MFI of the use plastic, at least higher than suitable for injection molding the relevant plastic. However, at the start of the injection of the plastic, the shape of the mold cavity 20 is adjusted such that a suitable MFR is obtained for the MFI of the plastic in question. The mold cavity is preferably brought increasingly further towards the final desired shape as the degree of filling increases, whereby the plastic is constantly kept moving and a suitable MFR is always maintained for the relevant or remaining part of the flow paths.

In a method according to the invention, it is preferred that the plastic is constantly kept moving during filling of the mold cavity by movement of mold parts and / or mold cavity parts. This prevents unwanted coagulation 30 from occurring, as a result of which undesirable haze formation can be prevented, in particular when transparent plastics A η Λ n Q o n 4 are used. In particular with plastics such as PET (polyethylene terephthalate) with particularly good transparency and high impact strength, a method according to the invention is particularly advantageous because it allows the clarity to be retained, also with mold shapes of thin-walled products, without using conventional blow molding techniques.

In further elaboration, a method according to the invention is preferably characterized by the features according to claim 4.

As a result of the thermal insulation of mold cavity-forming parts of the further mold, at least of cooling means thereof, the advantage is achieved that cooling of the plastic that is introduced into the mold cavity can be delayed, in particular until the mold is partially or completely closed, at least the mold cavity is completely filled in the final form. The heat capacity of the thermally insulated molded parts is preferably such that they can be heated up particularly quickly by the heated imported plastic, while these can be cooled relatively quickly by the cooling means of the mold. With such a method the flow of the plastic is promoted even better, while moreover with clear plastics this brightness is retained even better.

In a further advantageous embodiment, when the plastic is introduced, at least when the mold is closed, at least a part of the mold cavity forming parts is withdrawn, so that with substantially closed mold the volume of the mold cavity is greater than the volume of the final mold. forms product. After inserting at least substantially all of the required plastic, said retracted part is then actively moved into the mold cavity, such that the final desired shape of the product is obtained, whereby plastic is displaced to obtain the desired, complete filling.

4 Λ Q Λ 9 0 5

An additional advantage of a method according to the invention can be that stresses of the mold, such as with conventional injection molding, can at least largely lag behind, which can simplify the required devices and lead to shorter cycle times.

It is furthermore preferred that in a method according to the invention the plastic is dried prior to being fed into the mold cavity, at least that any moisture present therefrom is at least largely removed, whereby undesired disturbing influence of the moisture in the mold cavity is avoided. This is particularly advantageous, again, in the case of clear plastics, because haze formation is thereby even better prevented.

Surprisingly, it has been found that with a method according to the present invention, products can be manufactured in a simple manner that are thin-walled, in addition to which hinges can be formed. Such integrated hinges, commonly referred to as living hinges, offer the advantage that movable parts can be obtained without the necessity of mounting steps. With a method according to the present invention, such hinges can even be formed in substantially completely transparent products, that is to say products with a haze of less than 5%, more in particular less than 3%, whereby, for example, (blister) packages, containers and the like can be formed with a particularly pleasant appearance.

In a further advantageous embodiment, an at least partially container-shaped product is manufactured, wherein a label or similar cover is provided on the inside, which shields the plastic from content to be received therein. This prevents contact between the contents and the plastic during use, which is particularly advantageous when, for example, foodstuffs, pharmaceutical agents or the like have to be stored in the container. In such a method, recycled plastics can also be used in said application, such as recycled PE, PET, PS and the like. Moreover, this achieves the advantage that relatively inexpensive plastics, for example such as the aforementioned, can be used to manufacture relatively thin-walled container-shaped products which are light and yet sufficiently rigid.

In further elaboration such a label can be applied on the inside of said holder-shaped part, wherein a printing is provided on said label, on the side facing the wall against which this is arranged, or on said wall covered by said label, wherein the wall is made of a plastic that is at least partially and preferably completely transparent, so that said printing is visible from the outside of said product. Hereby the printing is protected against external influences, while, as indicated, contact between the plastic and the contents during use is avoided. For applying a label, for example, use can be made of in-mold label technology or the label can be introduced later. Of course, the printing can also be applied to the inside of the container, whereafter it can be covered, for example, by a protective lacquer layer or the like. In an alternative embodiment, at least said holder-shaped part of the product can also be labeled and / or printed on both sides, that is to say inside and outside.

The invention furthermore relates to a mold-shaped, substantially thin-walled plastic product, characterized by the features of claim 18.

Such a product offers the advantage that all kinds of special product properties can be obtained that were not possible with products according to the prior art. For example, products can be formed from plastic with a melt that is particularly low, for example an MFI smaller than 18, with wall thicknesses that are particularly small in comparison with the other dimensions of the respective wall parts.

For example, curved or flat wall parts can be obtained with a thickness of a few tenths of millimeters with outer dimensions of the relevant wall part of a few centimeters or more. Products that until now could only be manufactured from plastics with a high MFI, for example polyethylene or polystyrene.

A product according to the invention can be manufactured relatively inexpensively and simply from relatively inexpensive plastic, for instance impact-resistant, flexible, with integrated hinges, crystal clear or opaque, wherein moreover materials can be used which are less environmentally harmful than, for example, PVC.

A product according to the invention can for instance be manufactured from PET (polyethylene terephthalate) with for instance at least one integrated hinge and is particularly suitable as a storage device for for instance disc-shaped information carriers such as CDs, CDi, CD-ROM, Chipcard, Simcard or the like, but also for other products, for example writings, foodstuffs and the like, also as blister packs.

The invention furthermore relates to a device for forming products according to the invention or application of a method according to the invention, characterized by the features according to claim 27.

With such a device, products can be manufactured in a particularly simple manner that are relatively thin-walled, with relatively long flow paths, i.e. with a high MFR, from plastic with a low melt, or at least low MFI. With this, products can be manufactured with particularly advantageous product properties, such as, for example, high brightness, high impact resistance, high flexibility, low costs, FDA approval, recyclability, mono-packaging, suitability against low and / or high temperatures and the like, depending on the plastic chosen.

In a method and device according to the invention, the advantage is furthermore achieved that the closing force for closing and keeping the mold closed is relatively low relative to that required for the manufacture of comparable products in a conventional manner, i.e. by injection molding. This means that relatively small, light machines can be used.

Further advantageous embodiments of a method, product and device according to the invention are described in the further subclaims. To clarify the invention, exemplary embodiments of a method, product and device according to the invention will be further elucidated with reference to the drawing. In the drawing: Figure 1 shows diagrammatically in sectional side view a device according to the invention; figures 2 and 3 use the device according to figure 1 in two steps; figures 4A-C show the filling of a mold cavity in a method and device according to the invention in three steps; Fig. 5 is a sectional side elevation of an alternative embodiment of a device according to the invention; figures 6-8 show, in side, top and partially sectioned front view, a storage device according to the invention; Figure 9 schematically shows in side view a holder manufactured with a method and device according to the invention; figures 10A-C show in three steps the use of a device according to the invention, in an alternative embodiment; figure 11 shows diagrammatically in perspective view a product 30 with a device according to figure 10; Figure 12 shows a further alternative embodiment of a holder according to the invention; figures 13A-B show in sectional view a part of a wall of a product according to figure 12; and figure 14 shows diagrammatically in cross-sectional side view a device according to the invention in a further alternative embodiment.

In this description, the same or corresponding parts have the same or corresponding reference numerals. In this description use is made of the indications Melt-Flow-Rate (MFR) which is a usual indication of the ratio between the minimum passage height in a flow path, at least the minimum passage and the length of the flow path. Moreover, the term Melt-Flow Index (MFI) is used, which is a material-related index for the viscosity in "liquid" form, that is at a temperature at which the plastic 15 can at least flow slightly. The MFR and MFI are, among others, standardized in ISO standard 1133. It will be clear, however, that the application is not limited thereto.

Figure 1 shows diagrammatically in cross-sectional side view a part of a device 1 according to the invention, which comprises a mold 2 provided with a first mold part 4 and a second mold part 6. The second mold part 6 comprises a female part 8 of a mold cavity 10 in the first mold part 4 a male mold part 12 of said mold cavity 10. The male mold part 12 is defined by a molding 14 which is movably received in a cavity 16 in the first mold part 4. The molding 14 is hollow with relatively thin walls 18, indicated by the broken line, so that the heat capacity of this molded part 14 is relatively small. A thermally insulating seal 20 is provided around the mold part 14 over a part of the height of the chamber 16, while the first and second mold parts 4, 6 are provided with cooling means 22, schematically indicated by a pipe with a pump 1019320 10 24. These cooling means 22 are, for example, designed in the usual way as cooling channels (not shown) extending around the mold cavity 10 through which cooling liquid can be pumped at relatively low temperature, for example a few degrees Celsius.

In figure 1 the mold 2 is shown in the open position, such that a distance X exists between the closing surfaces 26. In the chamber 16 pressure means are included for biasing the molded part 14 in an extended position shown in figure 1, such that male part 12 is located at a relatively small distance Hi from the female part 8, at least the bottom 10 thereof. The pressure means in the chamber 16 can for instance be formed by a slightly compressible liquid, elastic material or the like or, as will be described in more detail with reference to Figure 5, comprise controllable pressure means. The pressure means 28 in the chamber 16 are designed such that upon introduction of plastic 30 into the mold cavity 10 in the chamber 16 the male part 12 can be pressed away, so that the distance between the male part 12 and the female part 8 increases, for example up to a distance H2. Plastic 30, for example polyethylene terephthalate (PET) or another plastic with a low Melt-Flow Index, for example less than 18, more in particular 20 less than 12 and preferably for example about 6 or less, via an injection channel 32 with the aid of a pump 34 or other injector known from the injection molding technique introduced into a mold cavity 10, displacing the molded part 14, which molded part is rapidly heated to a comparable temperature as a result of the temperature of the plastic, for example approximately 270 ° C for PET thermally insulated by the seal 20. This prevents premature change in the material properties, in particular coagulation and turbidity of the plastic 30, in particular the said PET. Prior to introduction of the plastic 30 into the cavity 10, the 1019320 11 plastic 30 is dried in a device 36, for example by suitable preheating, wherein moisture 38 is discharged.

After the plastic 30 has been introduced into the mold cavity 10 as a relatively thick, high viscose liquid, the space in the mold cavity 10 being relatively large as a result of the distance H2, the mold is closed, as shown in Fig. 3. In this condition the molding 14 is received almost completely in the chamber 16 and the closing surfaces 26 lie against each other. The mold cavity 10 is completely filled with plastic 30, the desired shape of the product 40 being obtained. A relatively large amount of contact exists here between the mold part 4 and thus the cooling means 22 and the mold part 14, so that the desired cooling of the product 40 is obtained, such that upon full opening, that is to say further than said distance X in figure 1, the product 40 can be taken out and the mold can be made suitable for a new production run. During the filling of the mold cavity and closing of the mold, care is taken to ensure that the plastic 30 continues to flow in the direction of the ends of the mold cavity 10, thereby preventing premature changes in material properties from occurring.

It has been found that, in particular when PET is used, for example, it is particularly advantageous if the plastic continues to flow during insertion and filling of the mold, while this plastic is almost completely dried prior to introduction and the walls of the mold cavity 10 are relatively warm during filling the mold, because the brightness of the plastic is thereby maximally retained. This offers the possibility of manufacturing thin-walled products as shown in, for example, Figures 6-9 as a replacement for, for example, polystyrene, polycarbonate, polypropylene and the like.

Figure 5 schematically shows, in cross-sectional side view, an alternative embodiment of a device according to the invention.

401 n Q O Π 12

Herein, not only is the male part 12 included as part of a molded part 14 movably in a chamber 16, but also the female part 8 on a second molded part 14A in a second chamber 18A in the second mold part 6. In this embodiment, the means 28 for prestressing the molded parts 14, 14A designed as at least one supply line 42 with a pump 44 for introducing and discharging from the chamber 16, 16A, respectively, a pressure fluid as hydraulic oil, with which the back pressure of the two is always accurate molded parts 14, 14A and thus the distance H can be controlled. Again, the mold parts 14, 14A of the mold parts 4, 6 are thermally separated by the sealing means 20, 20A, at least in the position shown in Figure 5. Only when the mold 2 is closed does thermal contact arise between the mold parts 4, 6 and the mold parts 14, 14A for cooling it and thereby the product. It will be clear that combinations of the different parts 15 as shown in Figs. 1-3 and 5 are possible.

Figures 4A-C schematically show the flow of the plastic 30 into the mold cavity 10. The plastic 30 is shown here by hatching, the mold cavity schematically as a rectangle.

In figure 4A the distance H2 between the mold parts is relatively large, as a result of which the plastic 30 has been displaced from the inflow line 32 over a relatively short distance Di in the mold cavity 10, on either side, at least to all sides. The flow front 50 is therefore close to the inlet opening 32.

After the desired amount of plastic 30 has been introduced into the mold cavity 10, the feed line 32 is closed, schematically represented by a cross 52 and the distance between the mold parts is reduced to Ηχ, thereby the flow front 50 is displaced in the direction remote from the feed line 32. so that the total flow path of the plastic 30 increases to D2. This means that the plastic is moved between figures 4A and 4B over a distance D2 - Di, with decreasing passage height H.

1 ii 1 93 2 0 13

When the mold parts, at least forming the mold cavity 10, move further towards each other, the flow front 50 is pushed even further until, as shown in Fig. 4C, the mold cavity 10 is completely filled and the desired product thickness Hi has been reached. It will be clear that just before the condition as shown in Fig. 4C is reached, the plastic must be pressed through a minimum passage height Hi. Since this only has to be done over a particularly short distance, a suitable Melt-Flow Rate, which matches the plastic, is always obtained.

Figure 6-8 shows a storage device 70, known per se from international patent application PCT / NL96 / 00459, which is hereby incorporated by reference. It is explicitly noted that this example should not be construed as being limitative in any way.

A device 70 according to the invention is particularly suitable for storing and transmitting information carriers such as CDs 72.

Information carriers should be understood in the broadest sense of the word and may also comprise other information-bearing products, such as paper, cardboard, plastic, provided with printing, figures, text or the like.

A storage device 70 according to the invention comprises a first cover part 74, a second cover part 76 and an intermediate part 78 connecting the two cover parts 74, 76. The cover parts 74, 76 are provided with edges 80, 82 in such a way that a closed package is closed. as schematically represented by the broken line 84. Closing means 81, 83 are schematically shown which can hold the storage device 70 in the closed position. The intermediate part 78 is connected on either side via an integrated hinge (living hinge) to an adjacent cover part 74, 76. Securing means 86 are provided on the intermediate part 78, for example in the form of pairs of clamping fingers 88 between which an edge of the information carrier 72 can can be clamped, as shown in figure 8. Optionally, the fingers 88 can be mutually connected by ridges 90 for increasing the clamping force. It will be clear that the information carrier can be secured in many different ways, at least confined within the storage device 70, for example also in a manner as known from the Jewel box on one or both cover parts 74, 76. Such and other fastening means are sufficiently known from practice.

In a particularly advantageous embodiment, an information carrier 70 according to the invention, for example as shown in the drawing, is manufactured from a clear transparent plastic such as PET and manufactured in a previously described manner, so that the transparency is completely retained. The haze can thereby be, for example, smaller than 5%, even smaller than 3%. With suitable process parameters, which can be easily determined by the person skilled in the art within the limits outlined, even a substantially completely haze-free plastic can be obtained.

Fig. 9 shows an alternative holder 92, in the form of a cup-shaped container 94 with a lid 98 connected thereto via a hinge 96. The hinge 96 is molded along, that is to say integrated with the container 94 and the lid 98. a blister package can be manufactured in the same manner, for example by making the container 94 slightly less high, whereby closing means 20 can be provided in the usual manner, which can be integrally formed, for confining a product or products to be packaged in the blister .

In a method according to the invention, for example applied to a holder 92 according to figure 9, different parts can get different transparency, for instance by previously cooling the cover part 98 of the mold, whereby this part is made somewhat milky white and less transparent opaque. It is even possible to give different cooling speeds by providing different surface parts of the mold cavity, as a result of which, for example, an opaque logo can be formed as an integral part on a relatively clear cover part, without, for example, other roughnesses being necessary, although possible.

Figures 10A-C schematically show, in cross-sectional side view, a device 1 according to the invention, in a further alternative embodiment, in three successive steps when a method according to the invention is applied. The same parts again have the same reference numerals.

In figure 10A the mold 1 is shown in the open position. The lower mold half 6 comprises a female part 8 of the mold cavity 10, the upper mold half 4 a male part 12, partly determined by a slider 13, which can slide along a fixed part 12A. In the embodiment shown, the slider is connected to a connecting rod 28A and a schematically shown piston-cylinder assembly 28B. However, of course, any other suitable means for moving the slider 13 can be used, for example as previously described. With the mold 1 open, as shown in Fig. 10A, the slider 13 is retracted, i.e., moved in the direction of the upper mold part 4, away from the female part 8.

In Fig. 10B, the mold halves 4, 6 are brought together, so that the mold cavity 10 is closed, the slide 13 being held in the retracted position and the volume of the mold cavity 10 being larger than the volume of the product to be formed. The distance H2 between the free end of the slide 13 and the opposite bottom surface of the female part 8 is thereby relatively large. In this state, plastic is introduced into the mold cavity 10 via the supply line 32. The amount of plastic is thereby adjusted to the volume of the product ultimately to be formed, for example a holder 92 as shown in Fig. 11.

After the plastic has been introduced into the mold cavity 10, as shown in Fig. 10C, the slide 13 is further moved into the female part 8 of the mold cavity 10, such that the distance H between the free end Λ Λ Λ Λ Ο Ο Π 13 and the bottom surface of the female part 8 corresponds to the desired wall thickness. As a result, plastic is displaced in the manner described above, so that a complete, at least desired filling of the mold cavity 10 is obtained.

Figure 11 shows diagrammatically in perspective view a product 92 with a holder-shaped part 93 and a rear wall 94, for example formed with a device according to figures 10 or 14.

Figure 12 shows an alternative embodiment of a holder-shaped product 92 according to the invention, for instance in the form of a butter tub, comprising a longitudinal wall 94 with a turned-over upper edge 95, wherein a content can be stored in the inner side 99, for instance foodstuffs such as butter or margarine, other lubricants, pharmaceutical or body care products or the like. Of course, other products can also be stored herein. On the inner side 99 of the wall 94, as shown in Fig. 13A, a covering 97 is arranged, in particular a plastic label which can be applied, for example, by in-mold labeling. The label 97 preferably covers the entire inside of the wall 94 up to or over the longitudinal edge 95, so that direct contact between the wall 94 and the contents on the inside 99 is avoided. The wall 94 can herein for instance be manufactured from recycled plastic without FDA approval, while the label 97 is preferably suitable for contact with foodstuffs, pharmaceuticals and the like. It is thereby preferred that the wall 94 is made of transparent plastic such as PET, wherein on the side of the label 97 facing the wall 94 a printing 91 is provided which is visible from the outside of the holder 92 through the wall 94. Incidentally, the printing 91 can also be applied to the wall 94 and subsequently covered by a covering, for example the label 97 mentioned.

1n1Q3? 0 17

Figure 13B shows a cut-through wall part of the holder 92, with a first label 97 on the inside and a second label 97A on the outside. Hereby the wall 94 is protected on both sides, while moreover an attractive appearance is obtained.

Figure 14 shows a further alternative embodiment of a device 1 according to the invention, somewhat comparable to that shown in Figure 10. However, in this embodiment, a slider 13 is movable in a direction Pi, perpendicular to the direction P2 in which the mold parts 4, 6 can be moved relative to each other. An activation slide 28 as operating means for the slide 13 is provided in the upper mold part 4, which is movable in a direction P3. In the embodiment shown in figure 14 a product 92 can be formed in this device 1 with a holder-shaped part 93 and a lid 98 connected thereto via a hinge 96. With the mold open (not shown), the slide 13 is moved away to the maximum, in figure 14 to the left, whereby a product 92 is released therefrom and can be removed. Subsequently, the slide 13 is moved back to the position shown in Figure 14 and the mold parts 4, 6 are pressed onto each other so that a mold cavity 10 is obtained with a content that is somewhat larger than the content of the product to be formed. In particular, a cavity 10A is provided for the free end 13E of the slide 13 shown on the right-hand side in Fig. 14. The distance H2 between the free end 13E and the opposite surface of the mold cavity is greater than the wall thickness to be formed there. After the mold has been closed and plastic 30 has been inserted therein, the slide 28 in Figure 14 is lowered, whereby, as a result of the cooperating, inclined surfaces 28C, 28D, the slide 13 is moved to the right by such a distance that plastic the cavity 10A is pushed away and the distance between the free end 13E and the opposite surface is reduced to a distance H according to the desired bottom thickness.

1n 1 q3? 0 18

Movement of the slider 28 can for instance be obtained with the aid of the mechanism with which the mold halves 4, 6 are pressed onto each other, but can also be effected in another way, for instance by external means, hydraulic, pneumatic or the like.

The holder 92 as shown in figure 14 can for instance be a multimedia storage device, as described earlier, but it can also be a different type of device provided with parts that can be formed with moving mold parts. It will be clear that any combination of methods, devices and products, as well as parts thereof and plastics which are mentioned only as examples, is possible within the scope of the invention as outlined by the claims.

With a method and device according to the invention, the additional advantage is achieved that relatively low injection pressures can be applied.

The invention is by no means limited to the exemplary embodiments shown in the description and the drawing. Many variations thereof are possible within the scope of the invention as set forth in the claims.

For example, different parts of different exemplary embodiments described can be combined and varied, for example different mold shapes and different means for creating back pressure for the movable mold parts. A plurality of mold cavities can also be included in one mold and products can also be formed without a hinge or with a plurality of hinges. Other plastics can be used with a relatively low Melt-Flow-Index, such as for example PC, PON, PEN and the like. Plastics with a higher MFI, such as PP, PE and the like, can also be processed with a method according to the invention, with which at least part of the advantages are achieved. Other types of products can also be manufactured with a method and device according to the invention, for example trays, household products, covering elements, while moreover other means can be used for closing containers, such as screw thread, bayonet means and the like, which are integral can be formed with it. All kinds of other means can also be used for biasing the movable mold parts. These movable molded parts can also be designed such that the mold parts are first brought against each other and then the or each molded part is moved such, for instance with means as shown in Fig. 5, that the mold cavity is brought into the desired shape. It is otherwise noted that an advantage of the previously described method is that venting of the mold cavity is possible in a particularly simple manner. If desired or necessary, the or each movable molded part can be preheated. It is also possible to use two component technology in a mold according to the invention and several injection points can be used.

These and many comparable variations are understood to fall within the scope of the invention as set forth in the claims.

ϋ λ 1 0¾ ^ 0

Claims (30)

1. Method for forming thin-walled products from plastic in a mold, wherein an amount of said plastic is introduced into a mold cavity, with at least partially opened mold, after which the mold is closed, such that the plastic in the mold cavity is passed through the mold cavity. wall parts of the mold cavity is pressed away, whereby a complete filling of the mold cavity is obtained.
2. Method according to claim 1, wherein a plastic is used with a relatively low melt, in particular a melt that is so low that the product to be formed therefrom cannot be molded into a mold by conventional injection molding.
3. Method as claimed in claim 1 or 2, wherein a mold is used of which at least one wall part is arranged movably, wherein during insertion of the plastic said at least one wall part is pressed away by the plastic, such that between said at least one wall part and an opposite wall part, a flow passage for the plastic is formed with a thickness measured between said wall parts that is greater than the thickness of the product part to be formed therefrom, said flow passage being slightly compressed to the desired thickness for the ter when the mold is closed product part to be formed on site.
A method according to any one of claims 1 to 3, wherein during the introduction of the plastic and the closing of the mold the plastic is kept in constant motion until the entire mold cavity is closed.
5. A method according to any one of the preceding claims, wherein a mold is used of which at least movable wall parts determining the mold cavity and preferably all mold-forming wall parts are thermally insulated from the further mold at 1 mold opened wall mold, wherein said mold thermally insulated wall parts of the mold are designed such that they have such a low heat capacity that the temperature of these wall parts is raised to near the temperature of the plastic when the plastic is introduced, while the other mold parts are kept relatively cool, while closing the the mold said wall parts of the mold cavity are cooled by thermal conduction between said wall parts and the further relatively cold mold parts.
6. Method as claimed in any of the foregoing claims, wherein a mold is used wherein the or each mold cavity comprises a male and a female part, wherein at least the male part is movably enclosed in a mold part, the confinement being embodied such that an outward facing face of the male part when the mold is opened is held relatively close to an opposite face of the female part, the plastic being inserted between said surfaces under such a pressure that the male part is slightly pressed away to provide a desired flow passage, wherein the pressure with which the male part is forced outward is smaller than the pressure of the plastic when introduced.
7. Method as claimed in any of the claims 1-5, wherein a mold is used wherein the or each mold cavity comprises a male and a female part, wherein at least the male part is movably confined in a mold part, the confinement being embodied such that an outwardly facing surface of the male part with the mold open is held relatively far from an opposite surface of the female part, the plastic being introduced, the male part being introduced in the direction of the female part at least after the plastic has been introduced forced to obtain the desired 4 ft λ r \ O o Π product, whereby the plastic is partially pressed into the mold cavity by the male part.
8. Method as claimed in any of the foregoing claims, wherein the plastic is dried prior to being fed into the mold cavity, such that at least largely the moisture is removed therefrom.
The method of claim 8, wherein drying of the plastic is achieved by pre-heating.
10. Method as claimed in any of the foregoing claims, wherein a mold cavity is used with a Melt-Flow Rate (MFR) that in closed condition is too high for the Melt-Flow-Index (MFI) of the plastic to be used, wherein the when the plastic is introduced, the mold is set such that at least a first part of the flow path has dimensions such that the minimum Melt-Flow index (MFI) and Melt-Flow-Rate (MFR) for the relevant plastic and product dimensions are met, wherein during and / or after introduction of the desired amount of plastic into the mold cavity the mold is closed, such that a flow front of the plastic is always created that is chosen such that the remaining part of the mold cavity still to be filled has a Melt Flow Rate (MFR) that matches the Melt-Flow Index (MFI) of the plastic.
A method according to any one of the preceding claims, wherein at least one hinge is formed in the mold cavity in the product.
A method according to any one of the preceding claims, wherein a clear, transparent plastic is used.
13. Method as claimed in any of the foregoing claims, wherein a plastic is used with an MFI that is smaller than 18, in particular smaller than 15, more in particular smaller than 10 and preferably at most 6.
A method according to any one of the preceding claims, wherein PET is used, at least a plastic with comparable MFI. 1019320
Method as claimed in any of the foregoing claims, wherein at least on the inside of a holder-shaped part of the product a label or similar cover is provided which shields the plastic from content to be received therein.
The method of claim 15, wherein the plastic used is at least partially recycled plastic.
17. Method as claimed in claim 15 or 16, wherein the plastic used is at least largely transparent, wherein said label is applied on the inside of the product, preferably by labeling in mold 10, wherein on said label a printing is applied which is through the wall of the product is visible.
18. Mold formed, substantially thin-walled plastic product, made from a plastic with a relatively small MFI, for example smaller than 18, wherein for parts of the product it applies that the MFR, calculated from an insertion position of the plastic in the mold cavity in which the mold cavity product is larger than the MFI of the plastic.
19. Product according to claim 13, wherein the product is formed from a plastic with an MFI smaller than 15, in particular smaller than 10, and preferably at most 6.
20. Product, preferably according to claim 18 or 19, which product is at least partially somewhat holder-shaped, wherein a label is arranged on the inside of said holder-shaped part, such that thereby the wall of said holder-shaped part is covered towards the inside .
The product of claim 20, wherein said plastic has no food authorization while the label does.
22. Product according to claims 18 - 21, wherein the plastic is transparent, in particular clear transparent with a haze of less than 5%, more in particular less than 3%. 191920
The product of any one of claims 18 to 22, wherein the product is made from PET.
The product of any one of claims 18 to 23, wherein the product is provided with at least one integrated hinge.
25. Product as claimed in any of the claims 18-24, wherein the product is a storage device for a multi-media carrier, in particular a storage device for a disc-shaped information carrier.
26. Product according to claim 25, wherein clamping means for the information carrier and closing means for the storage device are also formed.
27. Device for forming products according to one of claims 18 - 26 or for applying a method according to one of claims 1 - 17, comprising a mold with at least one mold cavity, wherein at least a part of the mold cavity wall is arranged movably and is biased into an extended position, means being provided for introducing plastic into the mold cavity, at least against said movable mold cavity wall part under such pressure that said mold cavity wall part can be pressed away thereby, means being provided for closing the mold after plastic has been introduced into the mold cavity, which means are arranged such that with the mold closed and the plastic cavity filled with mold the or each said movable mold cavity wall part is moved from the extended position to a collapsed position for determining the outer shape of the product to be formed.
Device for forming products according to one of claims 18 - 26 or for use of a method according to one of claims 1 - 17, comprising a mold with at least one mold cavity, wherein at least a part of the mold cavity wall is arranged movably and can be brought into a retracted position, wherein means are provided for introducing plastic into the mold cavity, at least against said movable mold cavity wall part, wherein means are provided for closing the mold after plastic has been placed in the mold cavity. mold cavity is provided, which means are arranged such that with the mold closed and the mold cavity filled with plastic, the or each said movable mold cavity wall part can be moved from the retracted position to an extended position for determining the outer shape of the product to be formed.
29. Device as claimed in claim 27 or 28, wherein the mold cavity is at least partially and preferably wholly determined by one or more molded parts which, when the mold is open, are thermally insulated from cooling means of the further mold, wherein when the mold is closed a thermal coupling is obtained between the or each molded part and the said cooling means, wherein the heat capacity of the or each molded part is relatively low with respect to the heat capacity of the further mold, at least of the cooling means, such that the or each molded part can be relatively fast are heated by the heat of the plastic to be introduced into the mold cavity, while these can be cooled relatively quickly by the cooling means.
30. Device as claimed in any of the claims 27-29, wherein furthermore means are provided for drying the plastic prior to introduction thereof into the mold cavity. j ft <
NL1019320A 2001-11-07 2001-11-07 Formation of thin-walled products from plastic mold comprises introducing heated plastic in mold cavity while mold is partly open, and pressing away plastic in mold cavity by wall parts of mold cavity NL1019320C2 (en)

Priority Applications (2)

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NL1019320A NL1019320C2 (en) 2001-11-07 2001-11-07 Formation of thin-walled products from plastic mold comprises introducing heated plastic in mold cavity while mold is partly open, and pressing away plastic in mold cavity by wall parts of mold cavity
NL1019320 2001-11-07

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
NL1019320A NL1019320C2 (en) 2001-11-07 2001-11-07 Formation of thin-walled products from plastic mold comprises introducing heated plastic in mold cavity while mold is partly open, and pressing away plastic in mold cavity by wall parts of mold cavity
CNB028261062A CN100522552C (en) 2001-10-25 2002-10-25 Method and apparatus for forming thin-walled products, and a product manufactured therewith
PCT/NL2002/000680 WO2003039838A1 (en) 2001-10-25 2002-10-25 Method and apparatus for forming thin-walled products, and a product manufactured therewith
TW91124980A TW568822B (en) 2001-10-25 2002-10-25 Method and apparatus for forming thin-walled products, and a product manufactured therewith
JP2003541711A JP2005507803A (en) 2001-10-25 2002-10-25 Method and apparatus for forming thin-walled products and products produced thereby
EP20020770316 EP1467851A1 (en) 2001-10-25 2002-10-25 Method and apparatus for forming thin-walled products,and a product manufactured therewith
US10/493,734 US7718110B2 (en) 2001-10-25 2002-10-25 Method and apparatus for forming thin-walled products, and a product manufactured therewith
HK05109242A HK1077254A1 (en) 2001-10-25 2005-10-20 Method and apparatus for forming thin-walled products, and a product manufactured therewith

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WO2004099480A3 (en) * 2003-05-08 2005-01-20 Fountain Patents B V Method and apparatus for manufacturing vehicle parts
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