CA1130523A - Process for eliminating densification of the bottom area during manufacture of blocks of polyurethane foam - Google Patents
Process for eliminating densification of the bottom area during manufacture of blocks of polyurethane foamInfo
- Publication number
- CA1130523A CA1130523A CA319,766A CA319766A CA1130523A CA 1130523 A CA1130523 A CA 1130523A CA 319766 A CA319766 A CA 319766A CA 1130523 A CA1130523 A CA 1130523A
- Authority
- CA
- Canada
- Prior art keywords
- foam
- temperature
- belt
- area
- tunnel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/20—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of indefinite length
- B29C44/28—Expanding the moulding material on continuous moving surfaces without restricting the upwards growth of the foam
Landscapes
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Polyurethanes Or Polyureas (AREA)
- Laminated Bodies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The disclosure describes a process for eliminating den-sification of the bottom area during the manufacture of blocks of polyurethane foam. It is characterized in that: (1) the end-less conveyor belt of the foaming tunnel of the foam-producing installation is made to function for a period of time of between 15 and 90 minutes, at the same time as the endless belt is heated, so that the surface temperature of the upper portion of the belt, which constitutes the floor of the tunnel, passes from room temp-erature to a temperature Tp of between 60 and 80°C; (2) the move-ment of the endless belt is stopped, a web of material, prefer-ably paper, is placed on the belt to be interposed between the foam and the plates of the belt, and immediately feeding is begun from the mixer-feeder head of the mixture of the reactants consti-tuting the foam upstream of the endless belt, the temperature during this stopped period decreasing from the value Tp to a value TR; (3) at the moment the value TR is attained the endless belt is again put into motion, operation is started of the devices for supplying and taking up the web of material, preferably paper, which covers the surface of the endless belt, controlling at the same time the temperature of the surface of the upper portion of the belt forming the floor of the tunnel so that in a first reac-tion area situated upstream of the endless belt it acquires a constant value TR, and in a second consolidation area another constant value TC, the temperature values being constant for each type of foam, and in that the time the temperature is maintained for each type of foam is determined by the ratio tT = tR + tC, tT
being the total time of permanence of the foam in the reaction tunnel, tR being the time it takes a foam element to traverse the reaction area, a fixed value for each type of foam and tC
being the time it takes a foam element to traverse the consolida-tion area; and (4) after leaving the foaming tunnel the block in formation undergoes, in at least one area located either before the drawing conveyors, between them or after the last of the conveyors which constitute the drawing means, drying in the lower part of the block in a so-called drying area which is held at a constant temperature TS notably higher than TR and TC, after the passing of which removal is made of the web of material, prefer-ably paper, to which is adhered a thin film of foam, thus obtain-ing a block of polyurethane foam having no densified bottom and a uniform surface which does not require final trimming.
The disclosure describes a process for eliminating den-sification of the bottom area during the manufacture of blocks of polyurethane foam. It is characterized in that: (1) the end-less conveyor belt of the foaming tunnel of the foam-producing installation is made to function for a period of time of between 15 and 90 minutes, at the same time as the endless belt is heated, so that the surface temperature of the upper portion of the belt, which constitutes the floor of the tunnel, passes from room temp-erature to a temperature Tp of between 60 and 80°C; (2) the move-ment of the endless belt is stopped, a web of material, prefer-ably paper, is placed on the belt to be interposed between the foam and the plates of the belt, and immediately feeding is begun from the mixer-feeder head of the mixture of the reactants consti-tuting the foam upstream of the endless belt, the temperature during this stopped period decreasing from the value Tp to a value TR; (3) at the moment the value TR is attained the endless belt is again put into motion, operation is started of the devices for supplying and taking up the web of material, preferably paper, which covers the surface of the endless belt, controlling at the same time the temperature of the surface of the upper portion of the belt forming the floor of the tunnel so that in a first reac-tion area situated upstream of the endless belt it acquires a constant value TR, and in a second consolidation area another constant value TC, the temperature values being constant for each type of foam, and in that the time the temperature is maintained for each type of foam is determined by the ratio tT = tR + tC, tT
being the total time of permanence of the foam in the reaction tunnel, tR being the time it takes a foam element to traverse the reaction area, a fixed value for each type of foam and tC
being the time it takes a foam element to traverse the consolida-tion area; and (4) after leaving the foaming tunnel the block in formation undergoes, in at least one area located either before the drawing conveyors, between them or after the last of the conveyors which constitute the drawing means, drying in the lower part of the block in a so-called drying area which is held at a constant temperature TS notably higher than TR and TC, after the passing of which removal is made of the web of material, prefer-ably paper, to which is adhered a thin film of foam, thus obtain-ing a block of polyurethane foam having no densified bottom and a uniform surface which does not require final trimming.
Description
3~s~3 ~ he present invention relates to an important improve-ment obtained in -the manufacture of bloc~s of polyurethane foam.
Specifically, it relates to obtaining blocks of polyurethane foam which do not have the densified bottom of the blocks obtained by the usual process.
As is known, polyurethane foarn is a plastic which has acquired increasiny importance over recent years. It is a pro-duct of many uses in such different industrial sectors such as, for example, the automotive industry and the textile industry.
In Spain, the distribution of consumpti.on of polyurethane foarn is represented by the following approximate percentages:
Upholstery 40%
Mattresses 38%
Automative 14%
Textile industry 3%
Others (containers for foods" toys, etc) 5yO
Total 100%
Polyurethane foam is basically the product of the re-20 action of a polyol with a polyisocyanate, which are the princi- ~ -pal ingredients. Other products are also necessary, such as water, catalyst, activator, blowing agents, dyes, etc. As is known to experts in -the art there is a great variety of types of foams, which is the result of the possibility of variation in the nature of the various components of which they are made, and in their relative proportions. ~mong the characteristics which can be varied, according to the selection of components and propor-tions, are stiffness, density, resistance to degradation, tensile strength, cell size, etc. Among the parame-ters involved, of spe-cial importance are -the nature of the polyol and of the polyiso-cyanate, and the ratio between polyol/polyisocyanate/water/blow-ing agent.
.3~ 3 Industrially, polyurethane foam is obtained in the form of blocks. These blocks can have a length of even more than 100 metres, their width normally bein~ 2 metres anc1 their height varying between 80 cm and 130 cm. The shape of the cross-section of the blocks of foam obtained by the conventional process is re-presented in Figure 1 of the drawings, which shall be described below on in this specification.
Independently of the type of foam produced, a serious problem associated with the manufacture of the block is the den-sification occurring in the bottom thereof. As a result of thisdensification it is necessary to waste an important part of the finished material, because its density is notably greater and its mechanical characteristics are very much inferior to those of the rest of the block.
As experts in the art will admit, frequently the per-centage of the densified area comes to be 5% by weight, even reaching 7%, in relation to the total weight of the block.
The disadvantage supposed by obtaining blocks of foam having a densified bottom is obvious, if the following fac-tors are considered:
a) The amount of wasted raw material can be of consider-able importance, in light of the fact that the daily production of an average-sized polyurethane foam installation exceeds 20,000 kg.
b) There is the added cost of trimming with proper mech-anical means, preferably saws designed specifically for this pur-pose, the densified layer of foam which can have a length of more than 100 metres (the length of the block~, a width of two metres and a thickness of 10-15 mm.
c) The difficulty of marketing said trimmed densified layer as a by-product.
d) Since an important part of the components OL the
Specifically, it relates to obtaining blocks of polyurethane foam which do not have the densified bottom of the blocks obtained by the usual process.
As is known, polyurethane foarn is a plastic which has acquired increasiny importance over recent years. It is a pro-duct of many uses in such different industrial sectors such as, for example, the automotive industry and the textile industry.
In Spain, the distribution of consumpti.on of polyurethane foarn is represented by the following approximate percentages:
Upholstery 40%
Mattresses 38%
Automative 14%
Textile industry 3%
Others (containers for foods" toys, etc) 5yO
Total 100%
Polyurethane foam is basically the product of the re-20 action of a polyol with a polyisocyanate, which are the princi- ~ -pal ingredients. Other products are also necessary, such as water, catalyst, activator, blowing agents, dyes, etc. As is known to experts in -the art there is a great variety of types of foams, which is the result of the possibility of variation in the nature of the various components of which they are made, and in their relative proportions. ~mong the characteristics which can be varied, according to the selection of components and propor-tions, are stiffness, density, resistance to degradation, tensile strength, cell size, etc. Among the parame-ters involved, of spe-cial importance are -the nature of the polyol and of the polyiso-cyanate, and the ratio between polyol/polyisocyanate/water/blow-ing agent.
.3~ 3 Industrially, polyurethane foam is obtained in the form of blocks. These blocks can have a length of even more than 100 metres, their width normally bein~ 2 metres anc1 their height varying between 80 cm and 130 cm. The shape of the cross-section of the blocks of foam obtained by the conventional process is re-presented in Figure 1 of the drawings, which shall be described below on in this specification.
Independently of the type of foam produced, a serious problem associated with the manufacture of the block is the den-sification occurring in the bottom thereof. As a result of thisdensification it is necessary to waste an important part of the finished material, because its density is notably greater and its mechanical characteristics are very much inferior to those of the rest of the block.
As experts in the art will admit, frequently the per-centage of the densified area comes to be 5% by weight, even reaching 7%, in relation to the total weight of the block.
The disadvantage supposed by obtaining blocks of foam having a densified bottom is obvious, if the following fac-tors are considered:
a) The amount of wasted raw material can be of consider-able importance, in light of the fact that the daily production of an average-sized polyurethane foam installation exceeds 20,000 kg.
b) There is the added cost of trimming with proper mech-anical means, preferably saws designed specifically for this pur-pose, the densified layer of foam which can have a length of more than 100 metres (the length of the block~, a width of two metres and a thickness of 10-15 mm.
c) The difficulty of marketing said trimmed densified layer as a by-product.
d) Since an important part of the components OL the
- 2 -.~ I
3L~3~15~3 foam is of petrochemical origin, the need is readily seen to economize those materials to the maximum considering the present high cost of petroleum and its derivatives.
It is deduced from the foregoing that the object of obtaining blocks without the lower densified area is highly desirable for the polyurethane foam industry.
me preceding problems and inconveniences are solved by the process of the invention which provides a block . without the densified area, thus attaining notable utilization 10 of the raw materials and a substantial saving in manufacturing ~ -costs.
According to the invention there is provi.ded a : process for eliminating densification of the bottom area during the manufacture of blocks of polyurethane foam, in which said . blocks are produced in a foam-producing installation which : includes a foaming tunnel, an endless conveyor belt formed of hinged plates, said belt running through the tunnel, a mixer- ~-feeder head for depositing a liquid mixture of reactants on ;
said endless belt at a location defining a foam upstream of said enaless belt, and drawing means made of drawing conveyors for drawing the polyurethane foam, characterized in that (1) the endless conveyor belt is made to function for a period of ~ -~
;~ time of between 15 and 90 minutes, at the same time as said : -endless belt is heated, so that the surface temperature of the upper portion of said belt, which constitutes the floor of the ~-tunnel, passes from room temperature to a temperature Tp of between 60 and 80C; (2) the movement of the endless belt is stopped, a web of material is placed on the belt to be inter- -posed between the foam and the plates of the belt, and immediately feeding is begun from the mixer-feeder head of the mixture of the reactants constituting the foam upstream of said ;.
endless belt, the temperature during this stopped period decreasing from the value Tp to a value TR; ~3) at the f~ _ 3 _ ~ ,, ~L~L30~23 moment the value TR is attained the endless belt is again put into motion, operation is started of devices for supplying and taking up the web of material which covers the surface of said endless belt, controlling at the same time the temperature of the surface of the upper portion o:E the belt forming the floor of the tunnel so that in a first reaction area situated upstream on said endless belt it acquires a constant value TR, and in a second consolidation area another constant value T~, said temperature values being constant for each type of foam, and in that the time said temperature is maintained for each type of foam is determined by the ratio tT = tR ~ tc~ tT being the total time of permanence of the foam in the reaction tunnel, tR
being the time .it takes a foam element to traverse the reaction area, said tR being fixed for each type of foam, and tc being the time it takes a foam element to traverse the consolidation area, and (4) after leaving the foaming tunnel the block in . formation undergoes, in at least one area located either before the drawing conveyors, between them or after the last of said conveyors which constitute the drawing means, drying in the ~ 20 lower part of the block in a drying area which is held at a : constant temperature TS higher than TR and Tc, after the passing of which removal is made of the web of material, thus obtaining a block of polyurethane foam having no densified bottom and a -. ~miform surface which does not require final trimming.
In order that the invention may be better understood, drawings are accompanied in which:
Figure 1 illustrates the cross-section of a block of foam as obtained by the conventional processO
Figure 2 is a schematic side view of the installation for producing polyurethane foam blocks in which the invention is carried out' and finally - 3a -1~3~5~3 Figure 3 is a graph showing temperature in C
on the vertical axis, and time on the horizontal axis. m e horizon-tal length CO' represents the time during which, with the endless conveyor belt of the foaming tunnel in operation without any feeding of the components of the foam, a hinged element thereof passes from ambient temperature to a value Tp.
The length o tOI~ represents the time during which said endless belt remains stopped. The length O"B' represents the time it takes an element of said belt, upon which foam is being formed, to pass through the foaming tunnel. Finally, the length B'G' represents the time it takes an element of the block of foam to travel the distance between the end of the foaming tunnel and the end of the drying area.
With reference to Figure 2, the following is a ; description of the conventional process for manufacturing blocks f l?oly-.
, .
:, , ` ~.
~ 3b -`` .~.~.~5i23 urethane foam. The fundamental parts of the installation are:
A foaming tunnel constituted by an inclined conveyor belt 1, formed by hinged plates P, the upper or conveying run of said belt constituting the floor of the foaming tunnel. The rest of said tunnel is formed by walls 5 and the roof T, in which as may be seen in the Figure there are three conduits for evacuating the gases which are formed and/or released during the reaction, such as C02 and the blowing agent. In the upstream par~ of the foam~
ing tunnel there is a mixer-feeder head MA, in which the various components of the foam are mixed in the proper proportions and then fed to the endless belt.
Situated beyond the endless conveyor belt, -the upper or conveying run of which constitutes the floor of the foaming tunnel, are several drawing conveyors, represented as 2 and 3 in Figure 2, which draw the foam formed in the foaming tunnel to an arrangement of idle rollers 6, from which the bloc~ of foam E is then cut and stored.
A web, which moves over the surfaces of the conveyors 1, 2 and 3 and has the same width as said conveyors, is inter-posed between the mass of foam E and said surface of the convey-- ors. Said web, fed from a supply reel 4, moves a-t the same speed ; as conveyors 1, 2 and 3, and is removed by a take-up reel 4'.
The web can be of paper, polyethylene film or any other material ~ -which has the necessary properties of strength, stiffness and ; resistance to rupture. The need for said web, which for conve-nience will hereafter be called "paper web", is because as has already been said, the moving conveyor does not have a continuous surface but rather is formed by a plurality of hinged plates ~
having a space between them. Thus the indispensable need for a ~ `
web of paper or of other material is easily understood if it is borne in mind that the foam ingredients deposited at the start of the tunnel are liquid at the moment of mixture in the mixer-; '' , .. ~ ~. . , : .: .
feeder head, 90 that without the paper web said mixed liquidwould pass into the hinges o-f the endless conveyor belt.
With respect to Figure 2 just briefly described, it must be noted that:
1) it represents merely a schematic representation and does not include all elements such as reactant tanks, pumps, con-veyor drive motors, etc.
!
2) in the installation in which the conventional pro-cess is carried out there are no elements as are represented here by Sl, S2 and S3, which constitute an aspect of the present in-vention which will be described farther on in this descrip-tive specification. This means that conveyors 1, 2 and 3, as well as the arrangement of idle rollers 6, are contiguous and do not have the separations or spaces between said conveyors as shown in Figure 2.
In the said installation, once operation commences at '~ the progxammed speed, conveyors 1, 2 and 3 as well as the devices for supply 4 and take-up ~' of the web, the li~uid mixture of ~
reactants is fed at the proper flow rate from the mixer-feeder head MA. and the liquid mixture of reactants is deposited at the upstream end of the foaming tunnel at A, upon the web of material which moves along with the floor of said foaming tunnel. At the moment of its deposit the reactant mixture is a viscous liquid which progressively reacts exothermically, increasing its volume and forming the block of foam. This phase of formation of the foam is represented in ~igure 2 by an ascending curve the position of which varies from one type of foam to another. so that point C
of the tunnel surface, which corresponds to the projection of the end of said ascending curve, can be moved to the right or to the left of its position in Figure 2, depending upon the reactivity of the formulation. After attaining its maximum height the formed block grows progressively in length, being drawn by the movement !
5 ~
~r.
5~23 :
of conveyors 1, 2 and 3. Upon passing the last of the drawing conveyors, represented by 3 in the Figure, and the paper web having been removed, the block is cut into pieces of varying size and after a curing period of 24 hours is stored.
The cross-section of sa:id block is represented in Fig-ure 1, in which can be seen the densified bottom area F whose undersurface is not smooth. Therefore said densified bottom F
must be trimmed to remove the densification and surface irregula-rities, with the inconveniences this supposes as explained above.
The improved process of the invention comprises, as a first step, running the endless conveyor belt of the foaming tun-nel without any feeding of the components of the foam, and rais-ing the temperature of the enclosure of said endless conveyor belt. The result of this heating is that the temperature of the upper portion of the belt forming the floor of the cited foaming tunnel passes, in a period of time ranging between 0 and 90 min-utes, from room temperature (Ta) to a temperature tTp) of about 80C, This temperature variation is represented in the left part ~1 of Figure 3.
,~ 20 The movement of the endless conveyor belt is then stop-ped for a proper period of time, the paper web is placed on the ' belt to be interposed between the plates of the belt and the -, block of foam, and in the upstream part of the said foaming tunnel the mixture of the reactants which create the foam begins --1 to be fed through the mixer-feeder head onto the paper web. Du-ring this period when the belt is stopped the temperature drops from Tp to a value called reaction temperature TR, fixed for each j type of foam, at which moment (point A of Figures 2 and 3) move-ment of the endless belt is resumed, and simultaneously the '!1 30 devices for feeding and taking up the paper web are activated.
Commencing from this moment, the temperatu~ of the sur-face of the upper portion of the endless belt of the foaming
3L~3~15~3 foam is of petrochemical origin, the need is readily seen to economize those materials to the maximum considering the present high cost of petroleum and its derivatives.
It is deduced from the foregoing that the object of obtaining blocks without the lower densified area is highly desirable for the polyurethane foam industry.
me preceding problems and inconveniences are solved by the process of the invention which provides a block . without the densified area, thus attaining notable utilization 10 of the raw materials and a substantial saving in manufacturing ~ -costs.
According to the invention there is provi.ded a : process for eliminating densification of the bottom area during the manufacture of blocks of polyurethane foam, in which said . blocks are produced in a foam-producing installation which : includes a foaming tunnel, an endless conveyor belt formed of hinged plates, said belt running through the tunnel, a mixer- ~-feeder head for depositing a liquid mixture of reactants on ;
said endless belt at a location defining a foam upstream of said enaless belt, and drawing means made of drawing conveyors for drawing the polyurethane foam, characterized in that (1) the endless conveyor belt is made to function for a period of ~ -~
;~ time of between 15 and 90 minutes, at the same time as said : -endless belt is heated, so that the surface temperature of the upper portion of said belt, which constitutes the floor of the ~-tunnel, passes from room temperature to a temperature Tp of between 60 and 80C; (2) the movement of the endless belt is stopped, a web of material is placed on the belt to be inter- -posed between the foam and the plates of the belt, and immediately feeding is begun from the mixer-feeder head of the mixture of the reactants constituting the foam upstream of said ;.
endless belt, the temperature during this stopped period decreasing from the value Tp to a value TR; ~3) at the f~ _ 3 _ ~ ,, ~L~L30~23 moment the value TR is attained the endless belt is again put into motion, operation is started of devices for supplying and taking up the web of material which covers the surface of said endless belt, controlling at the same time the temperature of the surface of the upper portion o:E the belt forming the floor of the tunnel so that in a first reaction area situated upstream on said endless belt it acquires a constant value TR, and in a second consolidation area another constant value T~, said temperature values being constant for each type of foam, and in that the time said temperature is maintained for each type of foam is determined by the ratio tT = tR ~ tc~ tT being the total time of permanence of the foam in the reaction tunnel, tR
being the time .it takes a foam element to traverse the reaction area, said tR being fixed for each type of foam, and tc being the time it takes a foam element to traverse the consolidation area, and (4) after leaving the foaming tunnel the block in . formation undergoes, in at least one area located either before the drawing conveyors, between them or after the last of said conveyors which constitute the drawing means, drying in the ~ 20 lower part of the block in a drying area which is held at a : constant temperature TS higher than TR and Tc, after the passing of which removal is made of the web of material, thus obtaining a block of polyurethane foam having no densified bottom and a -. ~miform surface which does not require final trimming.
In order that the invention may be better understood, drawings are accompanied in which:
Figure 1 illustrates the cross-section of a block of foam as obtained by the conventional processO
Figure 2 is a schematic side view of the installation for producing polyurethane foam blocks in which the invention is carried out' and finally - 3a -1~3~5~3 Figure 3 is a graph showing temperature in C
on the vertical axis, and time on the horizontal axis. m e horizon-tal length CO' represents the time during which, with the endless conveyor belt of the foaming tunnel in operation without any feeding of the components of the foam, a hinged element thereof passes from ambient temperature to a value Tp.
The length o tOI~ represents the time during which said endless belt remains stopped. The length O"B' represents the time it takes an element of said belt, upon which foam is being formed, to pass through the foaming tunnel. Finally, the length B'G' represents the time it takes an element of the block of foam to travel the distance between the end of the foaming tunnel and the end of the drying area.
With reference to Figure 2, the following is a ; description of the conventional process for manufacturing blocks f l?oly-.
, .
:, , ` ~.
~ 3b -`` .~.~.~5i23 urethane foam. The fundamental parts of the installation are:
A foaming tunnel constituted by an inclined conveyor belt 1, formed by hinged plates P, the upper or conveying run of said belt constituting the floor of the foaming tunnel. The rest of said tunnel is formed by walls 5 and the roof T, in which as may be seen in the Figure there are three conduits for evacuating the gases which are formed and/or released during the reaction, such as C02 and the blowing agent. In the upstream par~ of the foam~
ing tunnel there is a mixer-feeder head MA, in which the various components of the foam are mixed in the proper proportions and then fed to the endless belt.
Situated beyond the endless conveyor belt, -the upper or conveying run of which constitutes the floor of the foaming tunnel, are several drawing conveyors, represented as 2 and 3 in Figure 2, which draw the foam formed in the foaming tunnel to an arrangement of idle rollers 6, from which the bloc~ of foam E is then cut and stored.
A web, which moves over the surfaces of the conveyors 1, 2 and 3 and has the same width as said conveyors, is inter-posed between the mass of foam E and said surface of the convey-- ors. Said web, fed from a supply reel 4, moves a-t the same speed ; as conveyors 1, 2 and 3, and is removed by a take-up reel 4'.
The web can be of paper, polyethylene film or any other material ~ -which has the necessary properties of strength, stiffness and ; resistance to rupture. The need for said web, which for conve-nience will hereafter be called "paper web", is because as has already been said, the moving conveyor does not have a continuous surface but rather is formed by a plurality of hinged plates ~
having a space between them. Thus the indispensable need for a ~ `
web of paper or of other material is easily understood if it is borne in mind that the foam ingredients deposited at the start of the tunnel are liquid at the moment of mixture in the mixer-; '' , .. ~ ~. . , : .: .
feeder head, 90 that without the paper web said mixed liquidwould pass into the hinges o-f the endless conveyor belt.
With respect to Figure 2 just briefly described, it must be noted that:
1) it represents merely a schematic representation and does not include all elements such as reactant tanks, pumps, con-veyor drive motors, etc.
!
2) in the installation in which the conventional pro-cess is carried out there are no elements as are represented here by Sl, S2 and S3, which constitute an aspect of the present in-vention which will be described farther on in this descrip-tive specification. This means that conveyors 1, 2 and 3, as well as the arrangement of idle rollers 6, are contiguous and do not have the separations or spaces between said conveyors as shown in Figure 2.
In the said installation, once operation commences at '~ the progxammed speed, conveyors 1, 2 and 3 as well as the devices for supply 4 and take-up ~' of the web, the li~uid mixture of ~
reactants is fed at the proper flow rate from the mixer-feeder head MA. and the liquid mixture of reactants is deposited at the upstream end of the foaming tunnel at A, upon the web of material which moves along with the floor of said foaming tunnel. At the moment of its deposit the reactant mixture is a viscous liquid which progressively reacts exothermically, increasing its volume and forming the block of foam. This phase of formation of the foam is represented in ~igure 2 by an ascending curve the position of which varies from one type of foam to another. so that point C
of the tunnel surface, which corresponds to the projection of the end of said ascending curve, can be moved to the right or to the left of its position in Figure 2, depending upon the reactivity of the formulation. After attaining its maximum height the formed block grows progressively in length, being drawn by the movement !
5 ~
~r.
5~23 :
of conveyors 1, 2 and 3. Upon passing the last of the drawing conveyors, represented by 3 in the Figure, and the paper web having been removed, the block is cut into pieces of varying size and after a curing period of 24 hours is stored.
The cross-section of sa:id block is represented in Fig-ure 1, in which can be seen the densified bottom area F whose undersurface is not smooth. Therefore said densified bottom F
must be trimmed to remove the densification and surface irregula-rities, with the inconveniences this supposes as explained above.
The improved process of the invention comprises, as a first step, running the endless conveyor belt of the foaming tun-nel without any feeding of the components of the foam, and rais-ing the temperature of the enclosure of said endless conveyor belt. The result of this heating is that the temperature of the upper portion of the belt forming the floor of the cited foaming tunnel passes, in a period of time ranging between 0 and 90 min-utes, from room temperature (Ta) to a temperature tTp) of about 80C, This temperature variation is represented in the left part ~1 of Figure 3.
,~ 20 The movement of the endless conveyor belt is then stop-ped for a proper period of time, the paper web is placed on the ' belt to be interposed between the plates of the belt and the -, block of foam, and in the upstream part of the said foaming tunnel the mixture of the reactants which create the foam begins --1 to be fed through the mixer-feeder head onto the paper web. Du-ring this period when the belt is stopped the temperature drops from Tp to a value called reaction temperature TR, fixed for each j type of foam, at which moment (point A of Figures 2 and 3) move-ment of the endless belt is resumed, and simultaneously the '!1 30 devices for feeding and taking up the paper web are activated.
Commencing from this moment, the temperatu~ of the sur-face of the upper portion of the endless belt of the foaming
3~
tunnel - which is substantially the same as that of the conti-nuous paper web and consequently substantially equal to that of the bottom part of the block of foam in formation which rests upon said paper web - is r~gulated so that in a first area called the reaction area the aforesaid value TR is maintained, and in a ~ second area downstream of the first, called the consolidation-~ area. a value superior to TR is maintained, hereafter called Tc.
In at least one area downstream of the foaming tunnel, i the bottom of the consolidated moving block is sub~ected to a10 drying temperature called TS as it passes through a drying area.
In Figure 2 three drying areas are represented as Sl, S2 and S3.
Following the drying process, the paper web is -taken up and wound onto the take-up device 4', and adhered -to it can be w seen a thin uniform layer of foam. The block passing to the idle rollers has a bottom with no densification and a smooth and uni-form aspect which does not re~uire trim~ming, an indispensable , operation in the process of the prior art.
The foam in formation runs through the first area, the reaction area situated upstream o the bel-t, in a previously de-s, 20 termined time which varies from one foam to another. As has beenindicated, in this area the surface of the endless belt is held -at a constant temperature TR. which also varies from one foam to another. ~ ;
The time it takes the foam to traverse the consollda-tion area depends on the predetermined time in the reaction area.
' The fundamental parameters constituting the object of ;, the invention are defined as follows:
TR = Surface temperature of the reaction area.
C = Surface temperature of the consolidation area.
30 TS = Surface temperature of the drying area.
tR = The time it takes an element of the endless belt, or -the bottom part of the paper-lined block which rests on it to tra-., I .
~ 7 ~
verse the reaction area, that is, from point A to point C repre-- sented in Figures 2 and 3 of the drawings.
; tC = The time it -takes the aforesaid element to traverse the con-solidation area; that is, from point C to point B shown in Fig-ures 2 and 3 of the drawings.
tT = The time it takes the mentioned element to traverse the ~; floor of the foaming tunnel, that is, from point A to point B
shown in Figures 2 and 3 of the clrawings.
If it is borne in mind that the floor of the foaming tunnel traverses the reaction and consolidation areas, it is rea-dily seen that ., tT = tR + tC (1 ) and since the value of tR is predetermined for each type of foam, it is deduced that tC = tT ~ tR (2) While the values tR and TR are fixed for a given foam, they vary from~one foam to another, since as experts in the art will understand the exothermicity of the reaction of polyurethane formation varies according to the nature of the principal ingre-dients, and of the ratio between them. As was indicated pre-!~ viously, the principal ingredients are polyol and polyisocyanate.
However, the percentage of water in the mixture has an important role.
fundamental characteristic of the improvements ob-tained with the present invention is that the surface temperatures of the three areas fulfil the condition C ~ TS
, In general, the difference TC - TR - ~ T ranges from between 10 and 15C, about 10C being preferable. A temp-ature inside the foaming tunnel in the reaction area above a maxi-~3~ 3 .
mum limit can cause cracking of the foarn. and even its combustion.
Keeping in mind that this cracking temperature varies from one formulation to another, between approximately 45 and 80C, we have TR ~ C ~ 80C
The temperature of the drying area TS can attain appa-rently high values, ranging between 100 and 250C, in very short periods of time. This is not in contradiction with what was said ; above with respect to cracking and/or combustion, if it is kept in mind that said surface drying temperature is produced in an area outside the foaming tunnel, which is traversed by the block in a very short time.
Although in the foregoing only one drying area has been mentioned, the invention is not necessarily limited to only one area of this type and several can exist, although practical reasons limit this number to three. Nevertheless, a single dry~
ing area is the most preferable.
As a consequence of the difference in the mentioned three thermic levels, once the drying area is passed and the paper web is removed, a block is obtained having no densified bottom and a smooth and uniform surface, a thin and uniform layer of foam of a density similar to that of the rest of the block having re-mained adhered to the paper web.
;, The length of the belt 1 which constitutes the reaction ;~
area is represented by AC, CB being the longitudinal edge of the " consolidation area. From the foregoing it will be seen that the location of point C, although fixed for a given type of foam, varies from one foam to another and can be to the right or to the left of the position shown in the Fiyure.
Beyond the foaming tunnel itself three drying areas can _ g _ ... ., . ., , . ,, ., ~ ..,, ~ ,~, ,;, ,", , be seen in Flgure 2, represented by Sl, S2 and S3. Said drying areas are generally narrower in wid-th than the other -two areas, the width (or what is the same thing, the time it takes a certain element of the consolidated block to pass said drying area) being related with the temperature in inverse ratio. That is, a rela-tively narrow drying area (or its equivalent, a short time in passing that area) will require a high temperature and vice versa.
Figure 3 illustrates the temperature variation o a sur-face element of the foam block bottom with respect to time. In said Figure Oo' is the operation time of the belt of the foaming tunnel without any feeding of the components of the foam and O'O" is the stopping time of said belt, TR, TC and tR~ tc and Tt having the previously indicated meanings.
It can be easily seen that the transition of the temper-ature between the reaction and consolidation areas is not sudden and thus the inclined length of Figure 3 e~ists, point C being at a temperature which can be considered as intermediate between TR
and Tc. Once the plate element of reference has reached the point of return, the part of the block bottom in contact with said plate of reference undergoes, if the drying area Sl exists, a rise in temperature until the value TSl is reached. If the drying area lies downstream, for example at S2 or S3, the -temper-ature of the block commences to diminish, tending to equal that of the atmosphere. The dotted line represented by BF would be the variation of the temperature with respect to time if there -were no drying areas. ~t is also seen that the farther away the foaming tunnel, the higher the temperature will have to be in the drying area to counteract the decrease of the consolidation temperature. Naturally, once past the drying area the temperature of the block surface will diminish from points D, E or G of Fig-ure 3 to ambient temperature.
The removal of the paper web being one of the important ~3C~ 3 : aspects of the improvements obtained with this invention, it must be noted that while in the foregoing reference has been made to paper as the most common material used for the web inserted be-tween the block of foam in formation and the rectangular hinged plates which form the endless conveyor belt, any other weblike material can be used which fulfils the same function.
The following is an e~ample of how commercial polyure-thane foam can be obtained in accordance with the improved pro-cess of this invention. This example is given only for the pur-pose of illustration, and in no case must be considered limita-tive.
Feeding is made from the mixing head, in an operation as previously described, of a composition constituted by the fol-lowing materials in the amounts as indicated in parts by weight:
` Polyol 100 Toluenediisocyanate 51.3 Water 4.1 -~ Dimethylaminoethanol 0.4 ~~ Silicone ., Freon-ll ~trade mark) 6.5 i Tin octoate 0.2 `
Dye 0.3 The temperature of the reaction area is maintained at a ~~
value TR = 41.5 + 1C and the temperature of the consolidation area at a value TC - 51.5 + 1C, with a time tR = 2 to 3 min-utes in the reaction area and a time tc = 3 to 2 minutes of per-' manence in the consolidation area. A block is obtained which ` after being subjected to a temperature of 120C in the drying area, and the continuous paper web having been removed from the bottom, has a substantially uniform density throughout its vol-ume of 20 kg/m3, that is, without any densification in the bottom and without irregularities, and which does not need trimming.
S~;l' - 11 -:, , ;: , , . , - .
-~3~ 3 The following shows, by simple calculation, the econom~
ic advantages of the process of the invention.
An average-sized plant produces foam 200 days of the year and in each foaming produces a continuous block of 20 Tm, or in other words its yearly production is ~0 x ~00 = ~,000 Tm =
tunnel - which is substantially the same as that of the conti-nuous paper web and consequently substantially equal to that of the bottom part of the block of foam in formation which rests upon said paper web - is r~gulated so that in a first area called the reaction area the aforesaid value TR is maintained, and in a ~ second area downstream of the first, called the consolidation-~ area. a value superior to TR is maintained, hereafter called Tc.
In at least one area downstream of the foaming tunnel, i the bottom of the consolidated moving block is sub~ected to a10 drying temperature called TS as it passes through a drying area.
In Figure 2 three drying areas are represented as Sl, S2 and S3.
Following the drying process, the paper web is -taken up and wound onto the take-up device 4', and adhered -to it can be w seen a thin uniform layer of foam. The block passing to the idle rollers has a bottom with no densification and a smooth and uni-form aspect which does not re~uire trim~ming, an indispensable , operation in the process of the prior art.
The foam in formation runs through the first area, the reaction area situated upstream o the bel-t, in a previously de-s, 20 termined time which varies from one foam to another. As has beenindicated, in this area the surface of the endless belt is held -at a constant temperature TR. which also varies from one foam to another. ~ ;
The time it takes the foam to traverse the consollda-tion area depends on the predetermined time in the reaction area.
' The fundamental parameters constituting the object of ;, the invention are defined as follows:
TR = Surface temperature of the reaction area.
C = Surface temperature of the consolidation area.
30 TS = Surface temperature of the drying area.
tR = The time it takes an element of the endless belt, or -the bottom part of the paper-lined block which rests on it to tra-., I .
~ 7 ~
verse the reaction area, that is, from point A to point C repre-- sented in Figures 2 and 3 of the drawings.
; tC = The time it -takes the aforesaid element to traverse the con-solidation area; that is, from point C to point B shown in Fig-ures 2 and 3 of the drawings.
tT = The time it takes the mentioned element to traverse the ~; floor of the foaming tunnel, that is, from point A to point B
shown in Figures 2 and 3 of the clrawings.
If it is borne in mind that the floor of the foaming tunnel traverses the reaction and consolidation areas, it is rea-dily seen that ., tT = tR + tC (1 ) and since the value of tR is predetermined for each type of foam, it is deduced that tC = tT ~ tR (2) While the values tR and TR are fixed for a given foam, they vary from~one foam to another, since as experts in the art will understand the exothermicity of the reaction of polyurethane formation varies according to the nature of the principal ingre-dients, and of the ratio between them. As was indicated pre-!~ viously, the principal ingredients are polyol and polyisocyanate.
However, the percentage of water in the mixture has an important role.
fundamental characteristic of the improvements ob-tained with the present invention is that the surface temperatures of the three areas fulfil the condition C ~ TS
, In general, the difference TC - TR - ~ T ranges from between 10 and 15C, about 10C being preferable. A temp-ature inside the foaming tunnel in the reaction area above a maxi-~3~ 3 .
mum limit can cause cracking of the foarn. and even its combustion.
Keeping in mind that this cracking temperature varies from one formulation to another, between approximately 45 and 80C, we have TR ~ C ~ 80C
The temperature of the drying area TS can attain appa-rently high values, ranging between 100 and 250C, in very short periods of time. This is not in contradiction with what was said ; above with respect to cracking and/or combustion, if it is kept in mind that said surface drying temperature is produced in an area outside the foaming tunnel, which is traversed by the block in a very short time.
Although in the foregoing only one drying area has been mentioned, the invention is not necessarily limited to only one area of this type and several can exist, although practical reasons limit this number to three. Nevertheless, a single dry~
ing area is the most preferable.
As a consequence of the difference in the mentioned three thermic levels, once the drying area is passed and the paper web is removed, a block is obtained having no densified bottom and a smooth and uniform surface, a thin and uniform layer of foam of a density similar to that of the rest of the block having re-mained adhered to the paper web.
;, The length of the belt 1 which constitutes the reaction ;~
area is represented by AC, CB being the longitudinal edge of the " consolidation area. From the foregoing it will be seen that the location of point C, although fixed for a given type of foam, varies from one foam to another and can be to the right or to the left of the position shown in the Fiyure.
Beyond the foaming tunnel itself three drying areas can _ g _ ... ., . ., , . ,, ., ~ ..,, ~ ,~, ,;, ,", , be seen in Flgure 2, represented by Sl, S2 and S3. Said drying areas are generally narrower in wid-th than the other -two areas, the width (or what is the same thing, the time it takes a certain element of the consolidated block to pass said drying area) being related with the temperature in inverse ratio. That is, a rela-tively narrow drying area (or its equivalent, a short time in passing that area) will require a high temperature and vice versa.
Figure 3 illustrates the temperature variation o a sur-face element of the foam block bottom with respect to time. In said Figure Oo' is the operation time of the belt of the foaming tunnel without any feeding of the components of the foam and O'O" is the stopping time of said belt, TR, TC and tR~ tc and Tt having the previously indicated meanings.
It can be easily seen that the transition of the temper-ature between the reaction and consolidation areas is not sudden and thus the inclined length of Figure 3 e~ists, point C being at a temperature which can be considered as intermediate between TR
and Tc. Once the plate element of reference has reached the point of return, the part of the block bottom in contact with said plate of reference undergoes, if the drying area Sl exists, a rise in temperature until the value TSl is reached. If the drying area lies downstream, for example at S2 or S3, the -temper-ature of the block commences to diminish, tending to equal that of the atmosphere. The dotted line represented by BF would be the variation of the temperature with respect to time if there -were no drying areas. ~t is also seen that the farther away the foaming tunnel, the higher the temperature will have to be in the drying area to counteract the decrease of the consolidation temperature. Naturally, once past the drying area the temperature of the block surface will diminish from points D, E or G of Fig-ure 3 to ambient temperature.
The removal of the paper web being one of the important ~3C~ 3 : aspects of the improvements obtained with this invention, it must be noted that while in the foregoing reference has been made to paper as the most common material used for the web inserted be-tween the block of foam in formation and the rectangular hinged plates which form the endless conveyor belt, any other weblike material can be used which fulfils the same function.
The following is an e~ample of how commercial polyure-thane foam can be obtained in accordance with the improved pro-cess of this invention. This example is given only for the pur-pose of illustration, and in no case must be considered limita-tive.
Feeding is made from the mixing head, in an operation as previously described, of a composition constituted by the fol-lowing materials in the amounts as indicated in parts by weight:
` Polyol 100 Toluenediisocyanate 51.3 Water 4.1 -~ Dimethylaminoethanol 0.4 ~~ Silicone ., Freon-ll ~trade mark) 6.5 i Tin octoate 0.2 `
Dye 0.3 The temperature of the reaction area is maintained at a ~~
value TR = 41.5 + 1C and the temperature of the consolidation area at a value TC - 51.5 + 1C, with a time tR = 2 to 3 min-utes in the reaction area and a time tc = 3 to 2 minutes of per-' manence in the consolidation area. A block is obtained which ` after being subjected to a temperature of 120C in the drying area, and the continuous paper web having been removed from the bottom, has a substantially uniform density throughout its vol-ume of 20 kg/m3, that is, without any densification in the bottom and without irregularities, and which does not need trimming.
S~;l' - 11 -:, , ;: , , . , - .
-~3~ 3 The following shows, by simple calculation, the econom~
ic advantages of the process of the invention.
An average-sized plant produces foam 200 days of the year and in each foaming produces a continuous block of 20 Tm, or in other words its yearly production is ~0 x ~00 = ~,000 Tm =
4,000,000 Kg. Operating in accordance with the conventional pro-cess and supposing an average value of 4.5% in weight for the densified bottom, we have:
Yearly production of dense foam ~,000,000 X 0.045 = 180,000 Kg.
Yearly production of foam of uniform density 4,000,000 - 180,000 = 3,820,000 Kg.
A plant of the same size working with the process of the present invention, and estimating as 0.5% the percentage in weight of the thin layer of foam adhered to the paper web, would have a yearly pxoduction of foam of uniform density of:
~ 4,000,000 - (4,000,000 x 0.005) = 3,980,000 KgO
This means that with the process of the invention year-ly output would increase:
3,980,000 - 3,820,000 = 160,000 kg/year It is deduced from this that the advantage of the sys-tem consists of manufacturing 160,000 kg of foam without any cost of raw materials. Added to this saving would be the cost of power, labor, etc. necessitated by the trimming, storage and sale of the dense foam.
Yearly production of dense foam ~,000,000 X 0.045 = 180,000 Kg.
Yearly production of foam of uniform density 4,000,000 - 180,000 = 3,820,000 Kg.
A plant of the same size working with the process of the present invention, and estimating as 0.5% the percentage in weight of the thin layer of foam adhered to the paper web, would have a yearly pxoduction of foam of uniform density of:
~ 4,000,000 - (4,000,000 x 0.005) = 3,980,000 KgO
This means that with the process of the invention year-ly output would increase:
3,980,000 - 3,820,000 = 160,000 kg/year It is deduced from this that the advantage of the sys-tem consists of manufacturing 160,000 kg of foam without any cost of raw materials. Added to this saving would be the cost of power, labor, etc. necessitated by the trimming, storage and sale of the dense foam.
Claims (4)
1. Process for eliminating densification of the bottom area during the manufacture of blocks of polyurethane foam in which said blocks are produced in a foam-producing installa-tion which includes a foaming tunnel, an endless conveyor belt formed of hinged plates, said belt running through the tunnel, a mixer-feeder head for depositing a liquid mixture of react-ants on said endless belt at the upstream end of the endless belt upper run, and drawing means made of drawing conveyors for drawing the polyurethane foam, characterized in that (1) the endless conveyor belt is made to function for a period of time of between 15 and 90 minutes, at the same time as said endless belt is heated, so that the surface temperature of the upper portion of said belt, which constitutes the floor of the tunnel, passes from room temperature to a temperature Tp of between 60 and 80°C; (2) the movement of the endless belt is stopped, a web of material is placed on the belt to be inter-posed between the foam and the plates of the belt, and immed-iately feeding is begun from the mixer-feeder head of the mixture of the reactants constituting the foam upstream onto said belt, the temperature during this stopped period decreas-ing from the value Tp to a value TR; (3) at the moment the value TR is attained the endless belt is again put into motion, operation is started of devices for supplying and taking up the web of material which covers the surface of said endless belt, controlling at the same time the temperature of the surface of the upper portion of the belt forming the floor of the tunnel so that in a first reaction area situated upstream on said endless belt it acquires a constant value TR, and in a second consolidation area another constant value TC, the temp-erature value TC being higher than the temperature value TR, said temperature values being constant for each type of foam, and in that the time said temperature is maintained for each type of foam is determined by the ratio tT= tR + tC tT being the total time of permanence of the foam in the reaction tunnel, tR being the time it takes a foam element to traverse the reaction area, said tR being fixed for each type of foam, and tC being the time it takes a foam element to traverse the consolidation area; and (4) after leaving the foaming tunnel the block in formation undergoes, in at least one area located either before the drawing conveyors, between them or after the last of said conveyors which constitute the drawing means, drying in the lower part of the block in a drying area which is held at a constant temperature TS higher than TR and TC, after the passing of which removal is made of the web of material thus obtaining a block of polyurethane foam having no densified bottom and a uniform surface which does not require final trimming.
2. Process according to claim 1, characterized in that the difference of temperature between the area of consolidation and the area of reaction of the .DELTA. T = TC - TR is 15°C maximum, preferably 10°C.
3. Process according to claims 1 or 2, characterized in that the web of continuous material is selected from the group consisting of paper and film-forming material which resists the high temperatures of the drying area and has sufficient strength that it does not break.
4. Process according to claims 1 or 2, characterized in that the web of continuous material consists of paper.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ES466.102 | 1978-01-18 | ||
| ES466102A ES466102A1 (en) | 1978-01-18 | 1978-01-18 | Improved production of polyurethane for foam block |
| ES473730A ES473730A2 (en) | 1978-09-28 | 1978-09-28 | Improved manufacture of block of polyurethane foam |
| ES473,730 | 1978-09-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1130523A true CA1130523A (en) | 1982-08-31 |
Family
ID=26155941
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA319,766A Expired CA1130523A (en) | 1978-01-18 | 1979-01-17 | Process for eliminating densification of the bottom area during manufacture of blocks of polyurethane foam |
Country Status (18)
| Country | Link |
|---|---|
| AT (1) | AT381277B (en) |
| AU (1) | AU521610B2 (en) |
| BR (1) | BR7900294A (en) |
| CA (1) | CA1130523A (en) |
| CH (1) | CH635028A5 (en) |
| DE (1) | DE2900525A1 (en) |
| DK (1) | DK153303C (en) |
| FI (1) | FI783792A (en) |
| FR (1) | FR2414996A1 (en) |
| GB (1) | GB2012657B (en) |
| GR (1) | GR63066B (en) |
| IT (1) | IT1114302B (en) |
| MX (1) | MX150391A (en) |
| NL (1) | NL7900372A (en) |
| NO (1) | NO790027L (en) |
| PT (1) | PT69056A (en) |
| SE (1) | SE420582B (en) |
| YU (1) | YU7479A (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES423754A1 (en) * | 1974-02-28 | 1976-05-01 | Policastilla | Apparatus and methods of manufacturing expanded foam blocks of circular cross-section |
| DE2517664C3 (en) * | 1975-04-22 | 1981-06-19 | Metzeler Schaum Gmbh, 8940 Memmingen | Process for the continuous production of rectangular foam blocks |
| ES215157Y (en) * | 1975-09-16 | 1976-12-01 | Policastilla, S. A. | PERFECTED DEVICE FOR THE CONTINUOUS MANUFACTURE OF BLOCKS OF EXPANDED CELLULAR MATERIAL WITH CIRCULAR SECTION. |
| ES448190A1 (en) * | 1976-05-24 | 1977-08-01 | Roday Espumaciones Ind | Manufacture of polyurethane foam blocks with reduced compacting of peripheral portions |
| DE2748733A1 (en) * | 1977-10-29 | 1979-05-10 | 5090 Leverkusen | PROCESS AND EQUIPMENT FOR THE CONTINUOUS PRODUCTION OF BLOCK-SHAPED FOAM |
-
1978
- 1978-12-08 FI FI783792A patent/FI783792A/en unknown
- 1978-12-21 AU AU42789/78A patent/AU521610B2/en not_active Expired
- 1978-12-29 AT AT0937278A patent/AT381277B/en active
- 1978-12-29 GB GB7850274A patent/GB2012657B/en not_active Expired
-
1979
- 1979-01-03 FR FR7900122A patent/FR2414996A1/en active Granted
- 1979-01-04 NO NO790027A patent/NO790027L/en unknown
- 1979-01-05 IT IT47543/79A patent/IT1114302B/en active
- 1979-01-08 DE DE19792900525 patent/DE2900525A1/en active Granted
- 1979-01-10 PT PT69056A patent/PT69056A/en unknown
- 1979-01-11 SE SE7900266A patent/SE420582B/en not_active IP Right Cessation
- 1979-01-15 YU YU00074/79A patent/YU7479A/en unknown
- 1979-01-16 CH CH40779A patent/CH635028A5/en not_active IP Right Cessation
- 1979-01-16 BR BR7900294A patent/BR7900294A/en unknown
- 1979-01-17 GR GR58116A patent/GR63066B/en unknown
- 1979-01-17 MX MX176314A patent/MX150391A/en unknown
- 1979-01-17 CA CA319,766A patent/CA1130523A/en not_active Expired
- 1979-01-17 NL NL7900372A patent/NL7900372A/en not_active Application Discontinuation
- 1979-01-18 DK DK021979A patent/DK153303C/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| GR63066B (en) | 1979-08-06 |
| FI783792A (en) | 1979-07-19 |
| DK153303C (en) | 1988-11-14 |
| NL7900372A (en) | 1979-07-20 |
| SE7900266L (en) | 1979-07-19 |
| IT1114302B (en) | 1986-01-27 |
| GB2012657A (en) | 1979-08-01 |
| DK21979A (en) | 1979-07-19 |
| AU521610B2 (en) | 1982-04-22 |
| MX150391A (en) | 1984-04-30 |
| PT69056A (en) | 1979-02-01 |
| DE2900525A1 (en) | 1979-07-19 |
| IT7947543A0 (en) | 1979-01-05 |
| CH635028A5 (en) | 1983-03-15 |
| DE2900525C2 (en) | 1988-03-31 |
| FR2414996A1 (en) | 1979-08-17 |
| ATA937278A (en) | 1986-02-15 |
| AU4278978A (en) | 1979-07-26 |
| FR2414996B1 (en) | 1983-11-18 |
| DK153303B (en) | 1988-07-04 |
| SE420582B (en) | 1981-10-19 |
| GB2012657B (en) | 1982-03-31 |
| YU7479A (en) | 1982-10-31 |
| AT381277B (en) | 1986-09-25 |
| BR7900294A (en) | 1979-08-14 |
| NO790027L (en) | 1979-07-19 |
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| MKEX | Expiry |