Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
PROCESS FOR THE PREPARATION OF THERMOPLASTIC MATERIALS
Document Type and Number:
WIPO Patent Application WO/2009/013767
Kind Code:
A1
Abstract:
The object of the present invention is a process for the preparation of a material based on thermoplastic resin, in particular, a resin of the urea-formaldehyde type, a method for the processing of said material, as well as the use of said material for the preparation of finished items of various kinds such as, for example buckles, froggings (frogs), trays, dishes, handles, knobs, and hooks.

Inventors:
ZAVARITT RICCARDO (IT)
Application Number:
PCT/IT2007/000518
Publication Date:
January 29, 2009
Filing Date:
July 23, 2007
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
COROZITE S P A (IT)
ZAVARITT RICCARDO (IT)
International Classes:
C08L61/24; A44B1/02
Domestic Patent References:
WO2005111127A12005-11-24
Foreign References:
GB596363A1948-01-02
GB238904A1927-02-24
US4802838A1989-02-07
DE4237067A11994-05-05
Attorney, Agent or Firm:
TRUPIANO, Federica (Gilson e Trupiano S.r.l.Via Larg, 16 Milano, IT)
Download PDF:
Claims:
CLAIMS

1. Process for the preparation of a thermoplastic material based on a urea-formaldehyde resin that comprises a mixing step of at least one solid phase with at least one liquid phase, said liquid phase, or the total of said liquid phases being equal or higher than 15% in weight in relation to the said solid phase or the total of said solid phases.

2. Process according to claim 1 , characterised in that said liquid phase, or the total of said liquid phases is comprised between 20% and 40% in weight in relation to said solid phase or total of said solid phases.

3. Process according to claim 1, characterised in that said solid phase comprises at least one urea-formaldehyde resin.

4. Process according to claim 1 , characterised in that said liquid phase comprises water. 5. Process according to claim 1 , characterised in that said liquid phase, or total of said liquid phases has a pH comprised between 7 and 8.

6. Process according to claim 5, characterised in that said pH is equal to 7,4. 7. Process according to claim 1 , characterised in that said solid phase comprises other components selected among: flour, horn powder.

8. Process according to claim 1 , characterised in that said liquid phase comprises other components selected among: glycerine, glycol, and soda.

9. Thermoplastic material based on urea-formaldehyde resin, characterised in that it has a humidity percentage higher than 10%.

10. Thermoplastic material based on urea-formaldehyde resin according to claim 9, characterised in that it has a liquid content

comprised between 15% and 35% in weight in relation to the total weight.

1 1. Thermoplastic material based on urea-formaldehyde resin according to claim 10, characterised in that said liquid content is comprised between 20% and 30% in weight in relation to the total weight.

12. Thermoplastic material based on urea-formaldehyde resin according to claim 10, characterised in that said liquid content is comprised between 21% and 28% of the said paste weight. 13. Thermoplastic material based on urea-formaldehyde resin according to claim 9, characterised in that it is produced in logs having a total weight less than 10 kg .

14. Apparatus for the preparation of a thermoplastic material based on urea-formaldehyde resin that comprises: at least one extrusion unit mounted with a "cylinder" or "bell" in which said thermoplastic material is placed, at least one extrusion head, at least one cutting unit characterised in that said extrusion unit is equipped with at least one adjustable speed extrusion piston.

15. Apparatus according to claim 14, characterised in that said cutting unit has four blades.

16. Use of the thermoplastic material as in claims 9 to 13, for the preparation of buttons.

17. Use of the thermoplastic material as in claims 9 to 13, for the preparation of buckles, froggings (frogs), fashion accessories, small plaques, small general plates, switch plates, trays, dishes, sanitary components, WC seats, handles, knobs, and hooks.

18. Counter in thermoplastic material obtained according to the method as described in claims 1 to 8.

19. Button in thermoplastic material obtained through the

processing of said counter as in claim 18.

Description:

"PROCESS FOR THE PREPARATION OF THERMOPLASTIC MATERIALS"

************

FIELD OF THE INVENTION

The object of the present invention is to provide α method for the preparation of a material based on thermoplastic resins, in particular resins of the urea-formaldehyde type, a process or the preparation of said material, as well as the use of said material for the preparation of finished items of various kinds, such as buttons, buckles, frogs, trays, dishes, handles, knobs and hooks, for example. PRIOR ART

Among the ammine thermoplastic resins, particularly important are the urea-formaldehyde resins formed from the reaction between urea and formaldehyde, conducted according to variable schemes, depending on the specific resin characteristics to be obtained. Urea-formaldehyde resins are commonly used as adhesives, in particular in processes used for the preparation of rigid cardboards, plywood, and wood chipboard. They are also advantageously employed for the preparation of buttons of the so-called "synthetic" or "partially synthetic" type, as an alternative to buttons produced from materials such as mother of pearl, wood, glass paste, corozo, bakelite, galatite, or also as an alternative to buttons produced from different materials such as polyester, abs, nylon and acetate, for example. According to prior art, the method used for the preparation of urea- formaldehyde resin buttons, comprises a step of mixing a range of dry components, in the form of powders having different characteristics, among which also the basic urea-formaldehyde resin, with the minimum possible amount of liquid, having an aqueous base, in order to obtain a hard paste. Among the powders used for the mixing step,

α colorant or a colouring mix must be foreseen, destined to provide the final colour for the thermoplastic material, and therefore for the button that is to be prepared. Therefore the hard paste thus obtained is coloured in a uniform manner. In fact, since the amount of water or liquid employed during this processing stage is minimal, it would not be possible to colour the prepared paste in a successive step, because it would be too hard and difficult to model. Therefore according to this process, different pastes having different colours must be foreseen, having uniform colouring, since the colour must be introduced during the preliminary step of the preparation of the thermoplastic material paste.

Once the coloured paste has been obtained, this is "moulded" or "sliced" into sheets of variable thickness, each having a single uniform colour. At this point, the process involves the combination of different coloured sheets according to specific schemes and compositions in order to create a cylindrical "log" of thermoplastic material, composed of a plurality of sheets of various colours overlaid on top of one another, and which when seen in section, present a particular combination of colours, depending on the aesthetic effect required for the final button. Any colour effect and colour combination must be obtained by combining the sheets of coloured paste in a specific manner while forming the thermoplastic material "log". Once said "log" has been formed, it is placed in a specific closable cylinder also equipped with hinged jaws, having a fixed dimension, inside which the

"log" thus composed, is subject to a certain level of pressure to obtain complete adhesion between the various sheets that form the "log".

Following this step, the "log" which can also possibly undergo other processes, is inserted into a specific device equipped with a "cylinder"

or "bell" through which the material is extruded and sliced into sections forming discs of varying thickness and diameter to obtain so- called "counters". The top and bottom surfaces of the "counters" obtained in this manner possess colouring derived from the composition of the different coloured sheets used to form the initial "log". The "counters" thus obtained, are then processed according to traditional methods to obtain the finished button. The process according to the prior art as described above, presents numerous drawbacks. Since the mixture of the initial powders results in providing a hard paste, which cannot be easily moulded and can be only sliced into sheets of differing colour and thickness, but cannot be moulded to assume other forms, these single colour sheets must be combined in various ways in order to obtain a "log" whose section is composed of varying and interesting colours from an aesthetic point of view. It is obvious that in order to obtain more varied and complex colouring in the final log section, the number of sheet layers must be far greater in number for combination with one another in order to obtain, in section, a sophisticated and varying decorative pattern. The fact that it is necessary to combine such a high number of sheets leads to very large sized logs, having a weight that can vary between 20, 35 or even 40 Kg.

As well as being difficult to handle, these logs must be extruded using specific equipment after they have been placed in a cylinder having fixed dimensions, on which extrusion heads of various sizes and shapes can be mounted, to produce "counters" with a variety of different forms and sizes. The extrusion method used to convert the log into counters, according to prior art, foresees that after the log is positioned in the cylinder, it is extruded using constant force and

pressure suited to the hardness characteristics of the log in question. In this case, the speed and the amplitude of the counter cutting process are varied during the extrusion phase to obtain the shape and thickness required. However, in this case as well, the possibility of varying the cutting conditions is rather limited and this results in a limited range of shapes and sizes for the counters thus obtained. From the aforesaid description it is obvious that a large sized log will produce a large number of counters, and therefore a large number of buttons. However, it often occurs that the more complicated colourings require a limited sample range because of the need to vary the colouring pattern rather often but without the need for accumulating a large number of buttons.

In short, the method according to prior art always leads to the production of a large number of buttons that are then often difficult to sell. For this reason it is not advantageous from an economical production view point to create a great variety of different decorations, because in this way far too great a quantity of buttons would be produced for each different colour, and this would create marketing problems because of a number of buttons superior to market demands, leading to obvious drawbacks from an economical point of view.

Therefore the method according to prior art does not permit the production of a vast range of different colours without necessarily producing an excess of buttons that cannot be sold and that finish as waste products with obvious economical disadvantages.

The result of the aforesaid situation is that producers of urea- formaldehyde resin buttons according to prior art are not able to offer a wide sample range with a varied choice of buttons in different colours, colour combinations and decorations of different kinds, but

are forced to offer a limited choice, because of the productive limits described above. OBJECT OF THE INVENTION

The object of the present invention is to provide a process for the preparation of a thermoplastic material based on a urea- formaldehyde resin that is able to provide said material in a malleable and easily moulded form.

Another object of the invention is to provide a process for the preparation of a thermoplastic material with based on urea- formaldehyde resin that enables said material to be subjected to colouring at a successive step.

Yet another object of the present invention is to provide a method for the preparation of a thermoplastic material with based on urea- formaldehyde resin that permits further processing of the aforesaid material using various different conditions according to the required results.

A further object of the present invention is to use said material for the preparation of buttons having varying sizes, shapes and colours, even very complex. Yet a further object of the present invention is to provide an apparatus for the processing of said material. DESCRIPTION OF THE INVENTION

These and other further objects and further advantages that will be made more apparent by the following description, are achieved by a process for the preparation of a thermoplastic material based on urea-formaldehyde resin characterised in that it comprises a mixing step of at least one solid phase with at least one liquid phase, said liquid phase, or the total of said liquid phases, being equal to or higher than 15%, preferably comprised between 20% and 40%, in weight, with

respect to said solid phase or total of said solid phases, to obtain a paste whose liquid content is comprised between 15% and 35% in weight with respect to the total weight.

More specifically, said liquid content ranges between 21 % and 28% in weight in relation to said paste, and more specifically is approximately 26% of the weight of the said paste.

Again, according to the present invention, said solid phase comprises at least a urea-formaldehyde resin and said liquid phase comprises water. Furthermore, once again according to the invention, said liquid phase preferably has a pH level ranging between 7 and 8, more preferably equal to 7,4.

Advantageously said solid phase can comprise at least one urea- formaldehyde resin, other components of the type chosen from among: flour, horn powder and similar products, for example, while said liquid phase, in addition to or as an alternative to water, can comprise glycerine, glycol, soda and similar products. Using the process according to the present invention, the mixing of said solid phase and said liquid phase in the ratios described, leads to the forming of a paste which is far softer and more ductile than that previously obtained according to the prior art. In particular, given that the paste obtained according to the invention is softer and easier to manipulate, it can advantageously be obtained in a neutral colour, and successively different colorants can be added according to the colours required. Colouring is performed by adding a colorant or mixture of colorants to the soft paste which has been previously formed and placed in a paste mixer together with the colorant. According to the mixing level set in the machine, the paste will assume either a uniform or non-homogenous colour which can be

used to obtain special decorative effects. The aforesaid method represents a great advantage in relation to prior art because the traditional method does not provide non-homogenous colouring. Furthermore another advantage is the fact that since it is possible to apply colouring on a previously formed soft paste, the paste can be divided into portions and coloured in different ways to obtain small quantities of different coloured paste.

Once the soft paste has been obtained according to the invention, it is no longer necessary to perform any "slicing" operations, since the paste is easy to manipulate, malleable and easy to be processed. As a result, logs can be formed using previously moulded portions, or pre- shaped portions of soft paste in different colours, even non homogeneous, without the need to overlay different coloured sheets to realise the required decorative effect. The log obtained according to the process object of the invention, is therefore much smaller than the logs obtained using traditional methods according to prior art, but the colour and decoration of the counters obtained are penalised in no way. The advantage of using a log of a smaller size is represented by the fact that once it is positioned in the cylinder or "bell" and extruded, a lesser number of counters can be obtained, and therefore fewer buttons. This signifies that it is possible to produce a wide variety of different decorations without necessarily having to produce a too large a quantity of buttons for each sample range or production, thus making it simple to produce small batches in answer to current market flexibility.

The soft log, or thermoplastic material obtained according to the invention, has a humidity percentage higher than 10%, and generally has an average weight much lighter than the logs produced according to prior art. In fact, according to the invention, it is possible

to produce logs having a total weight of approximately 9 kg. According to the present invention, the soft log obtained in this manner, which as stated above, is characterised by a liquid content in relation to total weight, of between 15% and 35% in weight, preferably equal to approximately 26% in weight in relation to the total weight, can eventually be successively subjected to further processing, is placed in a specific cylinder or "bell" and extruded to produce counters that are processed successively to obtain the final buttons. The particular apparatus makes it possible to apply variable force and pressure on the cylinder, during the extrusion stage, thanks to an encoder or some other electronic component which permits piston travel control, a variable force and pressure, according to the characteristics of the paste to be extruded, in order to regulate the exit speed of the paste from the extruder head and consequently, also the blades that cut the extruded paste. Thus it is possible to vary the parameters of both the blade rotation speed an of the piston thrust, obtaining a corresponing variation of the thickness of the counters thus formed. The possibility of regulating the extrusion speed is provided exclusively by the ductile characteristics of the soft paste according to the invention. Furthermore, the extrusion apparatus, which also forms part of the present invention, permits the use of a A- blade cutting shaft, in place of the previous system using two blades only. The advantage to be gained in relation to prior art is obvious, in that the cutting speed can be increased considerably. Therefore, described schematically, the apparatus according to the invention foresees an extrusion unit comprising the "cylinder" or "bell" to contain the soft log, previously prepared, coloured and composed according to requirements, an extrusion head which is replaced according to the shape and size of the counters to be produced, a

cutting unit dedicated to slicing extruded materials into counters. As stated previously, the apparatus presents innovative aspects in relation to the extrusion unit which is equipped with a variable speed extrusion piston, to permit the extrusion of soft paste at various speeds, according to the thickness and the shape of the counter required. In this aspect, the apparatus differs from that of prior art, which has a constant extrusion speed, imposed by the characteristics of the hard paste to be extruded. Given that the method according to the invention is able to provide a soft paste which can be coloured and combined in different ways to produce a "log" having a smaller size than those used in prior art, the cylinder or "bell" mounted on the apparatus according to the invention, also represents an innovation in that it is manufactured in a size much smaller than the cylinders mounted on apparatus according to prior art. The advantage, once again, relates to the possibility of producing a limited quantity of counters, and therefore buttons, where necessary.

A further innovative aspect of the apparatus according to the invention is provided by the cutting unit which is able to work at a constant cutting speed, and can be equipped with a four-blade shaft, with the obvious advantage of increased cutting speed. In one embodiment of the present invention, the soft paste thus obtained can be advantageously subjected to at least one drying cycle in favourable temperature and humidify conditions. This also applies to the counters which after the extrusion stage can be subjected to at least one drying cycle and at least one pressing stage under predetermined conditions, according to the type of characteristics required of the finished product. Naturally the soft paste obtained using the process object of the

invention, can be processed using traditional equipment, regulating the amount of paste to be extruded in relation to the size of the cylinder.

The method according to the present invention, therefore provides a thermoplastic material that can be advantageously used for the production of buttons according to the aforesaid description, but it can also be advantageously used to produce items such as buckles, froggings, fashion accessories, small plaques, switch plates, trays, dishes, sanitary components, WC seats, handles, knobs, hooks and other small/medium components in general.

The same thermoplastic material can be advantageously subject to moulding to obtain different forms and applications. Below are indicated some examples for the preparation of a thermoplastic material suitable for button production. EXAMPLE 1

PREPARATION OF THE LIQUID PHASE = SYRUP

Kg

Water and dehydratation agent 1400 and 50

Emolient 30

Catalyst from 0 to 2

Base Up to pH=7,4

PREPARATION OF THE PASTE

Kg

Moulding powder 38

Additive ligands 9

Resin 26

Syrup 25

Total for 1 log 9

EXAMPLE 2 Kg

PREPARATION OF THE PASTE

Water 15

Base 0,1

Horn from 20 to 25 Moulding powder 15

Resin from 42 to 47 Emolient 0,200

Total for 1 log 9

According to the present invention, EXAMPLE 1 describes the formulation of a liquid phase as distinct from the solid phase. The two phases are successively mixed together to obtain a soft paste as described previously, characterised in that the liquid content is equal to approximately to 28% in relation to the final soft log. On the other hand, EXAMPLE 2 describes a formulation that does not foresee the preparation of a liquid phase separate from the solid phase, but foresees direct mixing of the various components. In this case a part of the liquid present in the soft log obtained by the mixing of the two phases, is provided by certain components which already contain a certain liquid percentage.

In the case of the formulation described in EXAMPLE 2, the liquid represents approximately 21% of the final soft log .