Plate and section manufacturing process and installation, and plates and sections obtained using said process

Abstract: This invention concerns a continuous manufacturing process of sections (11) or plates from soft matter (2) which is extruded under heat and encased by at least one strip sheet (3,3), said encased matter subsequently being calendered, shaped to the desired profile and finally cut into lengths. The process is particularly remarkable in that the matter used is a mixture containing a non-synthetic binder and water, so that the mixture becomes sticky by undergoing said heat treatment in an aqueous medium, which assures adhesion of the casing onto the matter during calendering, while the product undergoes at least one drying operation after said calendering operation. The binder is advantageously starch-based and the mixture may also contain a plasticizer, for example containing urea. The invention also concerns an installation for implementation of the process and the products thus obtained.

Description: This invention relates to a continuous manufacturing process for sections or plates, and more particularly for corner bars. The invention also concerns an installation to implement the process, and the products manufactured using said process. For the manufacture of corner bars, strips of paper or cardboard are known to be glued together and covered with a casing that is preferably impermeable. Also, paper-polythene complexes are known to be glued together under a flame and subsequently encased or not. Products entirely in plastic material also exist. However, French patent 2 528 350 filed by the same holder, suggests in interesting manner that sections and plates can be made from a soft material which is extruded under heat and encased in at least one strip sheet, which unit is subsequently calendered, shaped to the desired profile and finally cut into lengths. The material used is a thermoplastic material which may or may not contain other materials, and the process described in the above-mentioned patent is chiefly innovative compared with some other processes using thermoplastics, in that it avoids plastic flow of the thermoplastic material by fully encasing the material with one or two strip sheets taking care that the edges are properly covered. WO-A-9723333 discusses the replacement of thermoplastics packaging materials with environmentally friendly materials such as articles formed from starch-containing compositions. For example, articles may be formed by gelating starch in water, the starch is then heated so that it dries as a solid material. The invention sets forth a process of interest, of which one objective is to manufacture a product that is recyclable by the paper industry and/or biodegradable. For this purpose, the invention describes a process of the above-mentioned type, that is to say a manufacturing process using a soft material which is extruded under heat and encased at least in part by at least one strip sheet, and subsequently calendered, shaped to the desired profile and finally cut into lengths, characterised in that the matter used is a mixture containing a non-synthetic binder and water, so that the mixture becomes sticky by undergoing said heat treatment in an aqueous medium, which ensures that the casing adheres to the matter during calendering, while the product undergoes at least one drying operation after said calendering operation, and in that the casing is permeable or made permeable to steam in order to facilitate drying of the finished or semi-finished product. Not only does the invention give the benefit of all the advantages of biodegradable materials, but the choice of materials also assures simple, effective adhesion of the casing. In fully advantageous manner, the non-synthetic binder contains starch which becomes sticky after gelling and fusion due to the heat treatment in an aqueous medium. Generally, the starch-containing binder is derived from flour of non-foodstuff quality whose dry mass proportion in the mixture exiting the extruder is between 4 and 30%. Preferably, the sheet or sheets intended to form the casing are chiefly made up of resistant paper or cardboard, and they may evidently be made up of a complex. To assure good adhesion, the water content of the mixture exiting the extruder is, for example, between 4.5% and 15%. According to one embodiment, the mixture comprises a plasticizer, contained for example in the mixture in a dry mass proportion of between 5% and 15%, said plasticizer containing a fatty acid or urea. With a starch-based binder, the temperature of the material in the extruder is maintained between the melting point of starch, which depends upon its water content, and the degradation temperature of urea, this temperature being for example maintained for at least a certain time within a range of between 130°C and 150°C. The temperature is adjusted in relation to the chosen water content. Advantageously, the mixture also comprises biodegradable loads, the latter being for example contained in the mixture in a dry mass proportion of 40% to 85% and comprising mainly paper for example up to 4/5. According to one embodiment, the product undergoes drying during processing, using for example infra-red and/or micro-wave and/or high frequency radiation. However, and in addition, specific drying can be provided at the end of manufacture on each length of section or plate, which are passed in front of means blowing hot air. According to one embodiment, at least one of the sheets intended to form the casing is made permeable by perforation in numerous places before depositing the matter. The sheet or sheets intended to form the casing, may only partially surround the matter in order to facilitate drying of the finished or semi-finished product. The invention also concerns an installation for implementing the process, said installation comprising extrusion means for soft matter, means for encasing the latter at least in part, and processing means including means for its calendering, forming and cutting into lengths, the installation being characterized in that it also comprises drying means placed between at least some of said processing means, and means to perforate the casing. Said installation may also comprise a drying unit positioned after the length cutting means, said unit comprising means of blowing hot air and means of transporting section lengths. Finally, the invention evidently relates to any section or plate formed from the soft matter encased by at least one sheet which is manufactured according to the above-mentioned process. A particular embodiment will now be described with reference to the accompanying drawings; in which:- Figure 1 is an schematic side elevation of the manufacturing installation; Figure 2 is a perspective view of part of the installation; Figure 3 is a perspective view of the drying unit; Figures 4, 5 and 6 are cross sections through corner bars manufactured according to the invention; and, Figures 7, 8, 9 and 10 are plan views of sheets intended to form the casing. The drawings show, as an example, one manufacture of corner bars according to the invention, but they could evidently relate to other types of sections or even plates. In Figures 1 and 2, an extruder 1 is shown intended to produce a soft matter 2 in relatively thick ribbon form. Matter 2, which will be further described below in respect of composition, is deposited on strip sheet 3, which is unrolled from spool 4 then given translation motion, said matter 2 being carried by sheet 3 during its translation motion. As shown more particularly in Figure 2, sheet 3 is then folded along its longitudinal edges by system 5 to raise said edges and means 6 and 7 to fold the latter before it reaches a calendering device 8 (Figures 1 and 2). After calendering, the product is formed into a corner bar, in this example by passing through two pairs of rollers 9, 9' before being cut into lengths for example by knives 10 (Figure 1). The section lengths 11 thus obtained are then dried in a drying unit 12 illustrated in Figure 1 and seen in more detail in Figure 3. In the embodiment shown in Figure 2, sheet 3 only partly encases matter 2 so that a section of type 11a in Figure 4 is obtained, but it could evidently entirely encase the product as is shown by the section of type 11b in Figure 5. It would even be fully feasible to use two strip sheets and, for example, to have another strip 3' brought over the top of them as illustrated in the chain dotted line in Figure 1 in order to obtain a section of type 11c in Figure 6. Figure 1 also illustrates a cross section of different possible products under manufacture when the latter are still in flat shape, that is to say before they are formed. Also, for reasons which shall be explained below, sheet 3 (and possibly likewise sheet 3') is perforated, here by barbed roll 13 (Figures 1 and 2) in order to provide a multitude of perforations. Figures 7 to 10 show four types of sheet respectively 3a to 3d, sheet 3a not being specially perforated, while sheets 3b, 3c and 3d are possible examples of perforations, the perforations of sheet 3d (Figure 10) even representing special patterns or signs. The presence of perforations in the paper does not give rise to any technical problem when press gluing by calendering owing to the relatively low fluidity of the mixture and the considered working temperatures which shall be examined below. Soft matter 2 is obtained on exiting extruder 1 from a heated mixture containing a non-synthetic binder, of polysaccharide type for example, and advantageously containing starch or even proteins. The starch is derived for example from low quality flour which is a particularly advantageous starch source notably for cost reasons, such flour being for example contained in the mixture exiting the extruder in a dry mass proportion of between 4% and 30%. The mixture also contains a plasticizer of fatty acid type, for example, of between C12 and C30 or is advantageously urea-based, said plasticizer being contained in the mixture in a dry mass proportion of between 5% and 15%. With this plasticizer, the matter can be processed at lower temperatures and with a lower water content as shall be seen below. The urea has the advantage, among others, of exerting positive action on destructuration, gelling and fusion of the starch. Finally, the mixture contains water and various loads, preferably paper loads (shredded paper, sawdust, plant products etc..) in a dry mass proportion in the region of 40. to 85%, and possibly additives (borax, soda silicate, ...) The mixture's passage through the extruder assures mixing and homogenisation of the mixture, gelling then fusion of the binder, and finally produces the ribbon of matter. The water content of the mixture on exiting the extruder advantageously lies between 4.5% and 15%, that is to say evidently a higher content than on entering the extruder while the temperature of the matter inside the extruder is maintained at least for a certain time within a range of 130°C to 150°C, that is to say at a temperature that is higher than the melting point of starch and lower than the degradation temperature of urea. If this description gives dry proportions for the raw materials and water content for the mixture, it must be understood that each material comprises its own humidity and that water is not generally added to the mixture. The water content of urea and of the additives is in the region of zero while the water content of the flour is fairly constant (in the region of 14 to 17%) so that it is chiefly the biodegradable loads which are likely to alter the water content of the mixture. This is the reason why, while having a water content of between 5% and 15% for the mixture, the proportions of raw materials could have been given with their own humidity, the proportion for flour being increased from 4-30% when dry to about 5-35% with the relatively constant humidity level mentioned above, and it will be understood that the percentage of flour will relate in particular to that of the loads and vice versa. Sheet 3, and possibly sheet 3', are for the most part in paper or cardboard, but they may be in photographic paper or a paper-polyethylene complex, or otherwise (for example a complex containing aluminium..). The advantage of heat treatment in an aqueous medium of this matter so formed is to make it naturally sticky, so that sheet 3 or sheets 3 and 3' can be easily made to adhere to said matter during calendering, and consequently with no other particular means. On the other hand, owing to this humidity, the product must evidently undergo a drying operation and it even proved to be of advantage to conduct this drying during actual manufacture using, for example, apparatus such as 14, 15 and 16 (Figures 1 and 2), apparatus of infra-red lamp type (or even micro-wave or high frequency), apparatus 14 even being positioned on the manufacturing line before the ribbon of matter is even encased. Drying is important to allow the product to acquire optimum rigidity and mechanical resistance and to reach stable humidity as swiftly as possible. It is also for the purpose of facilitating drying that sheet 3 used is permeable and/or perforated (Figures 8, 9, 10) and that in the embodiment shown in Figure 2 the product is only partially encased contrary to French patent 2 528 350 initially cited. However, the cut section lengths require additional drying which may of course stabilize during storage, but a drying unit of the type shown by 12 in Figures 1 and 3 may also be provided. Drying unit 12 shown in closer detail in Figure 3, has transporting means 17 intended to collect section lengths 11 and cause them to move in front of means blowing hot air such as means 18 and 19 shown. It will be understood that the product thus obtained is advantageously recyclable and/or easily biodegradable. This product offers appreciable mechanical qualities owing to the use of a casing, which also allows inscriptions for example to be made. Numerous other means and variants can evidently be provided, in particular in respect of the casing of the matter or the number of ribbons of matter extruded at the same time, etc. The profiles obtained by the technique here above described are nevertheless sensitive to relative humidity (water vapour of gaseous H 2 O) due to their not negligible content of starch. It has been demonstrated that during long storage of these products above 65-70% relative humidity, a not negligible lowering in mechanical performance of the profiles was observed. The addition to the level of 2 to 10% in ratio to the quantity of starch present in the mixture, of calcium stearate, polyvinyl alcohol, malic anhydride or more polyethylene very effectively improves the performance of the product even after prolonged storage in a very humid area.

Claims: Continuous manufacturing process of sections (11) or plates from soft matter (2) which is extruded under heat and encased at least in part by at least one strip sheet (3,3'), said encased matter subsequently being calendered, shaped to the desired profile and finally cut into lengths, process characterised in that the matter used is a mixture containing a non-synthetic binder and water, so that the mixture becomes sticky by undergoing said heat treatment in an aqueous medium, which ensures adhesion of the casing onto the matter during calendering, while the product undergoes at least one drying operation after said calendering operation, and in that the casing is permeable or made permeable to steam in order to facilitate drying of the finished or semi-finished product. Process according to claim 1, wherein at least one of the strip sheets (3, 3') intended to form the casing is permeable. Process according to either of claim 1 or claim 2, wherein at least one of the strip sheets (3, 3') intended to form the casing is made permeable by perforating it in numerous places before depositing the soft matter (2). Process according to any one of claims 1 to 3, wherein the sheet or sheets (3, 3') intended to form the casing only partly surround the soft matter (2). Process according to any one of claims 1 to 4, wherein the non-synthetic binder is starch-based, which becomes sticky after gelling and fusion owing to the heat treatment in an aqueous medium. Process according to claim 5, wherein the starch-based non-synthetic binder is derived from flour which is contained in the mixture exiting the extruder in a dry mass proportion of between 4 and 30%. Process according to any one of claims 1 to 6, wherein the sheet or sheets (3,3') intended to form the casing are chiefly made up of resistant paper or cardboard. Process according to any one of the preceding claims, wherein the sheet or sheets (3,3') intended to form the casing are made up of a complex. Process according to any one of the preceding claims, wherein the water content of the mixture on exiting the extruder lies between 4.5% and 15%. Process according to any one of the preceding claims, wherein the mixture comprises a plasticizer. Process according to claim 10, wherein the plasticizer is contained in the mixture in a dry mass proportion of between 5% and 15%. Process according to either of claims 10 or 11, wherein the plasticizer is fatty acid based. Process according to either of claims 10 or 11, wherein the plasticizer is urea-based. Process according to claim 13, wherein the temperature of the matter in the extruder is maintained at between the melting point of starch, which depends upon its water content, and the decomposition temperature of urea. Process according to claim 14, wherein the temperature of the mixture is maintained for at least a certain time within a range of 130°C and 150°C. Process according to any one of the preceding claims, wherein the mixture also contains biodegradable loads. Process according to claim 16, wherein the biodegradable loads are contained in the mixture in a dry mass proportion of 40% to 85% and chiefly contain paper. Process according to any one of the preceding claims, wherein the product undergoes drying during processing. Process according to claim 18, wherein drying during processing is made by infra-red and/or micro-wave and/or high frequency. Process according to any one of the preceding claims, wherein one drying operation is conducted at the end of manufacture of each section or plate length, which are made to move in front of hot air blowing means. A process according to claim 5 or any claim dependent upon claim 5, wherein the starch based non-synthetic binder is chemically modified by the addition of a hydrophobic compound of calcium stearate or malic anhydride, to the level of 2-10% of the quantity of starch. A process according to claim 5 or any claim dependent upon claim 5, wherein the extuded product is made resistant to humidity by the addition of 2 to 10% of polyvinyl alcohol or polyethelyne in the ratio to the quantity of starch. Installation to implement the process according to any one of the preceding claims, comprising extrusion means (1) of a soft matter (2) and encasing means (5,6,7) to encase the latter, at least in part, and processing means including means for its calendering (8), forming (9,9) and cutting into lengths (10), characterized in that it also comprises drying means (14,15,16) positioned between at least some of said processing means and means to perforate (13) the casing. Installation according to claim 23, further comprising a drying unit (12) positioned after the means for cutting into lengths (10), said drying unit comprising means (18,19) to blow hot air and means (17) to transport section lengths. Section (11) or plate formed from soft matter which is encased by at least one sheet (3, 3'), manufactured by implementation of the process of any one of claims 1 to 22.

Inventors: BIRKEL THIERRY, DUCHANOIS DOMINIQUE, REGENASS PATRICE, VAN DE VEN JACQUES, BIRKEL, THIERRY, DUCHANOIS, DOMINIQUE, REGENASS, PATRICE, VAN DE VEN, JACQUES
Applicants: ITW LITEC FRANCE
Application year: 1999
Main classification: B29D31
IPC codes: C08L101, B29C69, D21J3, B27N3, B32B29, B29D99