NL8302884A - BUILDING PLATE, APPARATUS AND METHOD FOR ITS FORMATION. - Google Patents

Description

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Building board, device and method for its formation.

The present invention relates to construction products and more particularly to an apparatus and method for making construction products which are provided with non-woven webs or mats.

Techniques for forming non-woven webs from at least substantially dry components have been known for a long time; however, with the advent of high energy costs, the desirability of using such techniques instead of wet molding processes has become even more apparent.

Nevertheless, significant problems have been encountered in preparing dry-formed web materials with a relatively uniform structure. This invention relates to some special apparatus and method which can be used to prepare such uniform nonwoven webs as well as products provided with these webs.

Several patents are of particular interest in connection with the present invention. U.S. Patent 3,356,780 describes a cloth making apparatus. A mixture of fiber particles and binder 20 is fed into a chamber where it is contacted with a rapidly rotating cylinder and a pressurized air stream. The rapidly rotating cylinder and the air throw the fibers into slowly rotating perforated cylinders, the interior of which has a vacuum. The fibers 25 and the binder form a mat on the cylinders that roll together to form a layered fiber material.

U.S. Pat. Nos. 4,097,209 and 4,146,564 relate to a device, respectively. process for forming a mineral wool fiberboard product. A mixture of mineral wool fibers and a binder is prepared and fed through a venturi in an air stream of relatively high speed so that the material mixture is entrained and fed to a mat forming zone. In the mat forming zone, the material is deposited on converging open wire meshes by drawing air through the open wire meshes. The wire meshes are then converged to obtain a mineral wool fiberboard product. Unfortunately, the process and apparatus according to these patents have characteristics which essentially restrict them to the production of relatively thick materials having very variable basis weights.

The object of the present invention is to provide composite sandwich-like building materials, the construction of which can be varied as desired to obtain good acoustic properties or good strength properties and which have uniform basis weights.

This object is achieved with a building board as described in claims 1-7 / by the method of claim 8 and with the device described in claims 9-16.

The present invention comprises a building board, which is provided with a core material and non-woven outer surfaces, the plate being obtained by forming two non-woven webs, which consist of a binder and in principle inorganic fiber material, a core mixture consisting of a binder and a filler is placed between the webs; the webs and core mixture are reinforced to provide a composite structure and this structure is compressed and cured.

The present invention includes a method of forming a building board consisting of a core material and nonwoven outer surfaces, and this method comprises the steps of preparing a first mixture and a second mixture consisting of a binder and inorganic fiber material in principle made; the first mixture is fed into the upper zones of an upper mat forming zone and the second mixture into the upper zones of a lower mat forming zone, each mat forming zone consisting of a first movable open wire mesh disposed in its lower zone and, optionally, a second movable open wire mesh arranged to converge with the first open wire mesh at a pinch opening disposed therebetween, each mixture being introduced through a first opening so that it falls into and is entrained in a horizontal or upwardly directed air stream introduced by a second opening in each mat forming zone, 40 the second openings being provided with associated means for controlling the direction passing therethrough, the entrainment air being adjustable by suction the first open wire meshes and any second open wire meshes for optionally depositing the mixtures thereon and, wherein the second openings and any second wire meshes are disposed relative to the first open wire meshes so that the mixtures deposited on the wire meshes are deposited substantially evenly, thereby strengthening the deposited mixtures to form the top and bottom webs of material. and wherein a core mixture consisting of a filler and a binder is deposited on the bottom web and the resulting layered material is reinforced with the top web to obtain a composite structure and the composite structure is compressed and cured.

The present invention further comprises an apparatus for forming a building material consisting of a binder and inorganic inorganic fiber material, which apparatus is provided with (A) preparation means for preparing at least a mixture consisting of a binder and inorganic inorganic fiber material. (B) a first and second mat-forming zone, each zone in terms of supply belonging to a preparation agent for receiving a mixture therefrom and comprising (1) a first opening in its upper zone which opening is provided with means for introduction of the mixture therethrough, (2) a second opening arranged therein such that the air introduced through the second opening is directed horizontally or upwardly so that it crosses and entrains the mixture therein, the second opening having means associated therewith for controlling the direction of the air passing therethrough, (3) a first movable open wire mesh disposed in the lower zone of the mat forming zone, the wire mesh exiting the mat forming zone through a pinch opening, and, optionally, a second movable open wire mesh arranged to converge with the first open wire mesh at the pinch opening, the optionally disposed second open wire mesh s and the second opening with respect to the first open wire mesh are arranged 40 such that the mixture is deposited substantially uniformly on the wire meshes 8302384 f ΐ - 4 - s, (4) means for adjusting the entrainment air in an adjustable manner through the open wire meshes to optionally deposit the mixture thereon, (5) means for moving the first open wire mesh and the optionally applied second open wire mesh to the nip opening and (6) means to stiffen the deposited material nonwoven web, (C) means for converging the nonwoven webs formed by the first and second mat forming zones, and (D) means for stiffening the webs and hardening the binders.

The apparatus described in U.S. Pat. No. 4,097,209 has proven useful in producing mineral wool products with a thickness of about one inch or more. Although particle clumping and the presence of wave patterns have caused some difficulties, these difficulties are not particularly important because the product obtained had to be of a thick size. However, when thinner size products are desired, problems arise due to the presence of the clogs and waves which have been found to be virtually insurmountable.

Applicant teas herein have discovered that the primary cause of these problems is the sequential process of entraining the particulate material in the air stream and then introducing the entrained mixture into the mat forming zone. Rapid airflow is required to maintain entrainment. The feed mechanism that separates the mass of solids into individual particles and introduces them into the air stream attempts to develop a static charge on the particles. The rapid airflow 30 in combination with the static charge results in turbulence and lump formation of the particles. Small clogs of material initially form on the walls of the venturi as well as in the forming chamber. If the clogs collect more material, two effects are obtained. First, the clogs break off periodically and are deposited on the open wire meshes. Second, the clogs attempt to channel the passing air and thus cause an uneven entry of the particulate material into the mat forming zone. The latter effect, in combination with the rapid entry of the entrained material into the mat forming zone

Souk, q 8 4 fc- - 5 - and over the surfaces of the open wire meshes attempts to form uneven deposits and wave patterns in the material that is deposited on the wire meshes. The entrainment process is thus virtually excluded if uniform base weights are desired.

Surprisingly, applicants have discovered that significant improvements in base weight uniformity can be achieved by separately introducing the particulate matter and airflow into the mat forming zone and making other important changes in the known process. By variably directing the airflow horizontally or preferably upwardly into the particulate material fed through an opening located in the upper zones of the mat-forming zone so that the particulate material crosses and is entrained in the airflow and through the open wire meshes and Placing the openings relative to each other so that the entrained particles do not attempt to pass at high speed parallel to the surfaces of the open wire meshes prior to deposition, the problems of non-uniform deposition are reduced dramatically. As a result, uniform webs with uniform basis weights and thicknesses of the order of 1 mm can be produced on a routine basis.

The present invention will become apparent from the description of preferred embodiments that follow.

Fig. 1 illustrates an apparatus for preparing a nonwoven web according to the present invention, which apparatus comprises means for preparing a mixture consisting of a binder and fiber material, a mat forming zone and means for processing the mat that has been produced.

Fig. 2 illustrates an end view of a mat forming zone according to the present invention taken along line D-D of FIG. 1.

Fig. 3 illustrates a top view of a preferred aperture through which air enters the mat forming zone.

Fig. 4 illustrates a device consisting of two mat forming zones according to the present invention.

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The preferred device used to practice the present invention is illustrated in Pig. 1. Several features thereof are described in U.S. Patent No. 4,097,209, especially the means for preparing the particulate mixture and the curing and finishing agents. Mineral wool is typically received in bales 10 which must be cut into pieces before use. Fig. 1 illustrates bales 10 resting on a conveyor 11. The bales are partially sectioned at 12, transferred to the inclined conveyor 13, and then fed under a flail 14 causing an initial separation of the bales 10 into fibers 15. From the conveyor 13, the fibers 15 fall onto a conveyor 16 and are then fed onto an inclined pin-fed feed conveyor 17. At the top of the conveyor 17, the fibers are combed by a rotary comb 18 whereby the feed is leveled. The supplied material is thrown through the roll 19 into a gravimetric feeder 20 which is provided with a trough 21, compression rollers 22 and 23 and a flow rate balance 24. The device 20 feeds the fibers 15 through feed rolls 25 and 26 on a combing roller 27. The combing roller 27 drops the fibers 15 onto a conveyor 30 which carries them under a binder supply station 31. The binder feed station 31 also includes a gravimetric feeder (not shown) and deposits a desired amount of binder 32 on the fibers 15 fed on the conveyor 30. The layered fibers 15 and the binder 32 are mixed by a comb roller 33 and then fed in a shredder 34 of a first opening 35 of a mat forming zone 36. Shredder 34 comprises feed rollers 40 and 41, a retractor roller 42 and a take-off brush 43.

The mat forming zone 36, with the exception of wire meshes 45 and 46, is constructed where possible from material 35 which is substantially electrically non-conductive such as plexiglass. Although some metal parts are required for construction and other purposes, electrically conductive surfaces cause the deposition of statically charged particles on these surfaces. So they should be avoided whenever possible. Open wire meshes that are usually con-φ ‘ΓΓΓ a /.

The construction of a conductive material and the use of such material for the lower wire mesh 45 is preferred. However, a wider choice is possible with the top wire mesh 46 and may be constructed of a non-conductive material such as plastic. Air enters the mat forming zone 36 through a second opening 44 and entrains the mineral wool / binder mixture. The entrained mixture is then felted on the first open wire mesh 45 and the second open wire mesh 46 as described below. The wire meshes 45 and 46 are brought together at a pinch opening 47, at which point the felted mixture is reinforced in a reinforcing zone 48. Before exiting from the reinforcing zone 48 at the pinch opening 49, an upper tamping device 50 and a lower anti-stiffener are promoted. static device 51 separates the reinforced material from the open wire meshes. The reinforced material passes over transfer rollers 52 in an oven 53 where it can be dried, cured or the like.

Although the mat forming zone 36 includes a first open wire mesh 45 and a second open wire mesh 46, as preferred, it is also to be noted that in some cases it may be possible to omit the second open wire mesh 46. Wire mesh 46 could thus be replaced, for example, by a panel of non-conductive material or a dense wire mesh. Nonwoven webs produced using the device comprising only an open wire mesh may in some cases have relatively more random particle size distributions than webs produced using an apparatus comprising two such wire meshes. Nevertheless, in many cases, and especially in the production of core building boards, the random distribution of particles makes little difference in the final product.

When such changes are applied, other changes to the device will also be required. For example, if the second wire mesh 46 is replaced by a panel, the reinforcement of the felted web could be done very suitably at the pinch opening 47 using a sealing roller. Furthermore, the absence of an upper wire mesh in the reinforcing zone 48 would in most cases obviate the ramming device 50, the primary function of which is to separate the path of this upper wire-5. gauze.

In the preferred embodiment shown in Figs. The wire mesh 45 in direction A passes through the lower zone of the mat forming zone 36, while the wire mesh 46 enters into the mat forming zone 36 by passing around the wire mesh roll 58, and moves in the direction B to the nip opening 47 and exits the mat forming zone 36 by passing around the wire mesh roll 59. The open wire meshes 45 and 46 are provided with means 60 to 63 for drawing air through these wire meshes. The mat forming zone 36 also includes ceiling sections 64 and 65, a hood 66 in which the felting device 34 is mounted, a rear panel 67 and side panels 68 and 69 (Fig. 2).

The second opening 44 is provided in the rear panel 67 and is oriented upwardly so that the air supplied into the mat forming zone 36 through this opening generally passes in the direction C. It is also possible to allow the air to enter through the opening 44 in a horizontal manner; however, a less satisfactory felting is achieved with a horizontal embodiment. Furthermore, as a warning, downward directing of the air through the opening 44 should be avoided because extremely poor results are often obtained.

Although shown in Figs. The illustrated preferred embodiment depicts openings 35 and 44 as individual openings, the present invention also encompasses those devices which, for reasons of size or otherwise, include multiple openings which allow the particulate material or air into the mat forming zone. Thus, the use of single terminology herein will be understood to include a multiple of the indicated device.

Preferably, the second opening 44 will also include means for variably controlling the direction of the incoming air as it enters mat forming zone 36. Oscillating blades have been found particularly suitable 40 and shown in FIG. 2 and 3, wherein FIG. 2 is OS C 2 3 84 ♦ t ·· - 9 - taken along lines D-D of FIG. 1 and FIG. 3 is a plan view of the second opening 44.

The second opening 44 consists of side panels 73 and 74, a top panel 75 and a bottom panel 76, with the two ends of this opening open. A row of blades 77 is arranged within the opening. The blades 77 are mounted on pins 78, which rotatably engage the top panel 75 and the bottom panel 76 so that the blades 77 pivot about the axes of the pins 78. The ends of the blades 77 furthest from the mat forming zone 36 are connected to a blade oscillation axis by connectors 80. While the sheared blade configuration has been found to be particularly suitable for controlling the direction of air flow, other flow control means arranged in or behind the second opening 44 or in the mat forming zone 36 may also be advantageously used. . Thus, all of these air control means are contemplated by the present invention.

During operation, the first open wire mesh 45 and the second open wire mesh 46 are moved in the direction A, respectively. B (Fig. 1) so that they converge at the pinch opening 47. Suction means 60, 61 and 62 draw air from the mat forming zone 36 through the first open wire mesh and suction means 63 draw air through the second open wire mesh.

The extracted air is replaced by air entering the mat forming zone through the second opening 44. Thus, an underpressure is always maintained in the mat forming zone 36.

Mineral wool is the preferred inorganic fiber material for practicing the present invention, but other fibers can also be used. Examples of such material are inorganic fibers of glass, ceramic material and wollastonite, natural fibers such as cotton, wood fibers or other cellulosic materials and organic fibers such as polyester or polyolefins. Furthermore, other materials such as perlate and different clays can also be used.

When a mixture of binder and mainly inorganic fiber material is introduced through the first opening 35, it is crossed by the upwardly directed air entering through the second opening 44. The 40 blade arrangement of the second opening 44 channels the air 8302884-10 in a variable manner. and the opening 44 is preferably oriented such that the air crosses the mixture of material immediately below the first opening 35. The resulting entrained mixture of material is deposited on the first 5 and second open wire meshes 45 and 46 as the entrained air is extracted through these wires. The manner in which the air is extracted through these wires can be varied as desired by those skilled in the art to obtain products with different properties. Although a single suction means can be used behind each wire mesh, Figs. a plurality of suction means 60, 61 and 62 disposed below the first open wire mesh 45. The air suction can thus be varied in two ways, namely by varying the amount of suction through the different zones of a single wire mesh, for example, via the means 60, 61 and 62 and by varying the relative amounts extracted by the upper and lower wire meshes 46 and 45.

Fine particles lighter than large particles try to follow the airflow and are therefore felted on those parts of the wire mesh through which most of the air is extracted. Thus, for example, if 90% of the air is extracted through one wire mesh, most of the fine particles will be deposited on that wire mesh. Layering and basis weight control will also be affected by variable suction of air through different parts of a single wire mesh. It will therefore be clear that if thin strips are desired, variable extraction of the air via means 60, 61 and 62 is very advantageous. Under these conditions, most of the air is preferably extracted through the wire mesh 45 to the rear of the mat forming zone using the suction means 62, while smaller amounts are extracted using the suction means 60 and 61. Variable suction is another a way of avoiding turbulent passage of the entrained material across the surface of the wire mesh 45 at the pinch opening 47, the consequences of which are indicated below.

Variable air extraction also provides an alternative to replacing the second open wire mesh 46 with a panel or closed wire mesh. Thus, by depositing the suction means behind the wire mesh 46, almost all air will be extracted through the first open wire mesh 45. However, this alternative is not entirely satisfactory because even if all the air passes through the wire mesh 45, part of the particulate material will stick to the wire mesh 46, leading to some thickness variation in the resulting product.

A major drawback of the device described in US Pat. No. 4,097,209 was the lack of uniformity of the material obtained. A number of factors contributing to the unevenness have been explained above; however, another factor not mentioned is the narrow angle between the converging open wire meshes. Due to this narrow angle, as the entrained material enters the mat forming zone, the particulate material streaks across the surfaces of the open wire meshes at great speed. This turbulent passage coincided with the static charges present on the entrained material, resulting in wave patterns in the deposited material.

For these reasons, the angle between the wire meshes 45 and 46 at the pinch opening 46 should be such that turbulent passage of the entrained material across the surfaces of these wire meshes is avoided. The angle illustrated at the pinch opening of the device described in U.S. Patent 4,097,209 is about 12 °; however, according to the present invention, it has been found that angles of not less than about 20 ° are preferred. Furthermore, the angle should not be too great because material deposited on the wire mesh 46 tends to crack or fall off the wire mesh as it passes around the wire mesh roll 59 specially produced as 35 thick mats. Thus, a maximum angle of not more than about 55 ° is preferred.

In addition to the horizontal or upward supply of air through the second opening 44 referred to previously, another factor influencing the manner in which the particulate material is deposited on this open is 83 0 2 8 8 4 h.

* * - 12 - * wire mesh where the second opening 44 is provided in the rear panel 67. If the point of intersection of the incoming air and the particulate material is too far below the opening 35, appropriate entrainment cannot occur and the particulate material passes at a relatively flat angle across the first open wire mesh 45. Both effects promote wave patterns and unevenness. Thus, it is preferable that the second opening 44 is provided in the upper parts of the back panel 67.

Similar problems can also arise if the second opening 44 is facing down into the particulate material or if it is too far away from the first opening 35. For a device constructed as illustrated in the Pig. and having an approximate size as described below, it has been found that the best results are obtained if the distance between the first opening 35 and the first open wire mesh 45 is not less than 90 cm and if the distance between the inner end of the second opening 44 and the point where the upwardly directed airflow crosses the material-mixture is about 60 cm.

While these results can be varied somewhat by increasing the angle on the pinch opening 47, this angle and the location of the second opening 44 can both be varied to achieve the same result. Thus, it should be borne in mind that it is desirable that the particulate material approach the surfaces of the open wire meshes 45 and 46 in a non-turbulent and approximately non-parallel fashion.

The blades disposed in the second opening 44 make a particularly valuable contribution to the present invention. The build-up of wave patterns with time in the prior device was due in part to channeling caused by the statically induced deposition of the particulate materials in different parts of the passage through which the entrained material passes, and in part in the manner in which the entrained material passes over the material previously felted on the open wire mesh. The blades 77 attempt to overcome this problem by oscillating back and forth. When shaft 79 oscillates back and forth generally along the 8302884 c-13 track EP (Fig. 3), the blades are first directed to one side of the mat forming zone 36 and then to the other side of this zone. As a result, there is little chance of channeling and the particulate material deposited on the open wire mesh 45 and 46 is much more uniform.

The advantage of the present invention is clearly seen in the nature of the material produced with the present device according to the present method. As previously indicated, only 10 relatively thick products could be obtained using the earlier devices. For example, when a mixture of binder and mineral wool fiber is entrained in an air stream and passed into the mat forming zone described in U.S. Pat. No. 4,097,209, materials having a thickness of about 2.5 cm or more and many uneven zones obtained. Thick products can also be obtained according to the present invention but they can be produced at a high line speed and they do not have any of the clumps or wave patterns inherent in the prior art products.

As another example of the advantage of the present invention, prior art attempts to obtain thinner materials have been completely unsuccessful due to the clumps found in the final product. Such difficulties do not arise with the present invention. Nonwoven webs of uniform basis weights and thin construction have been obtained using the present apparatus in which the present process is carried out. The advantages of these thin material layers are remarkable. For example, by using two mat forming zones as described herein, it is possible to form sandwich-like building products with thin outer layers and a central core. An example of such a device is illustrated in

Fig. 4, wherein the means for preparing the particulate mixture and the curing and finishing agents are not trimmed.

A lower mat forming zone 83 and an upper 40 mat forming zone 84 are constructed as previously described, and as with the individual mat forming zones, they may optionally contain one or two open wire meshes. Mixtures of binder and a suitable fiber material are supplied to each zone and are converted into webs of material as described previously. The webs exit from zones 83 and 84 at the pinch openings 85, respectively. 86. The bottom web 87 is fed from the conveyor 88 over transfer rollers 89 to the conveyor 90. A core deposition station 91 then deposits a core mixture 92 onto the web 87 and a thickness gauge 93 levels the core material. Station 91 includes a gravimetric feeder (not shown) such as that previously described.

Meanwhile, the upper web 94 exits the pinch opening 86, passes over transfer rollers 95 on the conveyor 96 and down along the slide 97 depositing it on the top of the leveled core mixture. The loose composite material can then be compressed by a pre-compression assembly 98 in which case it emerges from the pinch opening 99 as a structure having sufficient strength to be able to transport it through further processing and curing steps without undergoing significant damage.

A wide variety of products can be obtained by using this device. For example, if a mixture of expanded perlite and binder is used as the core mixture, the products produced can be varied from those having good acoustic properties to those having high fracture values. Furthermore, the plate is produced in a single pass operation 30, which is special. The prior art teaches that some sandwich-like products can be produced by separately making the outer layers and then adhering them to a core material with a layer of adhesive. The present invention is remarkably more favorable not only because of its simplicity in avoiding the adhesive layers but also because the nature of the process allows differential compaction of the product without resorting to separate laminating and pressing operations.

40 The above, of a perlite core for 83 0 2 834: - 15 -

This product is a particularly good example of this I.

phenomenon. The outer layers of mineral wool and binder have a low compressive strength, while the expanded per- I

the core has a relatively high compressive strength. When the composite structure is compressed, the core I works

as an anvil against which the outer layers are pressed together.

This leads to compaction of the outer layers, but almost I.

no compaction of the core. At the same time, the core I

irregularities in the outer layers, resulting in smooth I

10 outer surfaces with uniform density are obtained.

Another method of differential differential I

sealing the composite structure includes the back I

subsequently hardening the core and the outer layers. For example I

image, if a composite structure is manufactured with I.

15 a core with a binder which has a lower curing temperature than the binder for the outer layers and the composite is passed through a convection

oven set at a temperature at which the core I

tape material hardens but not the outer layer tie

20, a structure with uncured outer I is obtained

layers. If these outer layers are then pressed against I.

the core and hardened, can be very dense outer layers I.

obtained. Likewise, the same effect can be obtained by using binders with similar curing properties but with a necessary curing component omitted from the outer layer binder. When the necessary component is then added and the composite material is compressed and cured, dense hard outer layers are again obtained. An example of the latter alternative is the use of a binder such as a novalak phenol formaldehyde resin from which the cross binder hexamethylene tetramine has been omitted.

These and a variety of other structures with different characteristics can be produced according to the present invention. Other advantages I

parts of the present invention will become even more apparent with reference to the following examples.

Example I

This example illustrates the preparation of a product with about 87% mineral wool and 13% powdered phenol binder, the resulting product having a thickness of about 3.8 cm and a density of about 96 3 kg / m. The product was manufactured using the dual baking mold zone device as shown in FIG. 4. Reference numbers refer to the numbers used in Figs. The lower mat forming zone 83 used for this and the following examples was constructed from plexiglass so that the distance between the pinch opening 47 and the back panel 67 is about 272 cm, the zone width measured between the side panels 68 and 69 was about 65 cm and the height measured vertically between the wire mesh 45 and the center point of the retractor roller 42 was about 105 cm. The angle of the pinch opening 47 was about 25 °. The top mat forming zone 84 had a distance between the pinch opening 47 and 15 the rear panel 67 of about 210 cm, the width and the height were about the same as for the mat forming zone 83.

The angle at the pinch opening 47 was about 48 °.

For each mat forming zone 83 and 84, mineral wool fibers were separated and fed to the conveyor 20 at a rate of 3.44 kg per minute using a Vectroflo gravimetric feeder. The phenolic resin was fed to the fiber through the station 32 at a rate of 1.02 kg per minute. This material was mixed together by the combing roller 33 and fed to the various shredders 34.

The wire meshes in the respective chambers were converged at about 3 m per minute and air was supplied to the respective chambers at a volume of about 142 m3 per minute and extracted through the forming wires 45 and 46. The pressure within each forming chamber was about 5. 3 cm of water under atmospheric pressure, measured using a Dwyer meter. In the lower molding chamber, approximately 90% of the entraining air was extracted through the lower molding wire mesh 45, with most of this air being occluded by the suction means 62. In the upper molding chamber, approximately 60% of the air was aspirated through the upper molding wire mesh 46 with no attempt to variably extract the air. The blades 77 were oscillated within each opening 44 at about 30 cycles per minute.

40 The mat materials were converged at the pinch openings 47 and reinforced in the reinforcement zones 48. Immediately prior to exit from the reinforcement zones 48, the composite materials were simultaneously rammed by the ramming devices 50 and exposed to the anti-static devices 51. The ramming devices 50 were adjusted to strike the back of the wire mesh 46 approximately 30 times per minute, alternately compressing and releasing the mats. These devices promote the reduction of mechanical bonding. The anti-static devices 51 were conventional alpha particle emitters that remove the charges from the fiber mats and reduce static adhesion. When these devices were used individually or not at all, complete separation of the mat materials from the wire meshes was not obtained. However, the simultaneous use of these devices has yielded good separation leading to high quality products.

The individual webs exiting from the mat forming zones 83 and 84 were converged and pre-compressed using the pre-compression assembly 98. This device was adjusted so that the pinch opening contacts the reinforced web very lightly. The stiffened material was then fed into a continuous convection dryer oven (TCD) and exposed to the air heated at about 205 ° C for about 3 minutes. During this exposure time, the resinous binder was melted and at least substantially cured. The distance between the pressure conveyors of the TCD oven was about 3.9 cm; therefore, when the plate emerged from the TCD-over in a slightly plastic state, it was recalibrated and cooled. Post-calibration adjusted the thickness of the plate to about 3.8 cm and cooling with the ambient air simultaneously reduced the plate temperature to slightly less than 121 ° C. The product produced in this way without the use of an after-calibration device was found to be a thickness variation of ± 1 mm, while material produced using the post-calibrator was found to have a thickness variation of ± 0.25 mm.

40 The acoustic performance of products formed in this 8302884 s-18 manner was: sound insulation class (NIC) of 20 and sound reduction coefficient (NRC) of 95. Thus, it was suitable for a variety of high performance acoustic applications.

Example II

This example illustrates the manufacture of a sandwich-like product with an overall composition as follows:

Weight percent 10 Ingredient (solids base) mineral wool 24.21 powdered phenolic binder '1.82 expanded perlite 64.35 liquid phenolic resin 9.62 15 The outer layers consisted of 93% mineral wool and 7% powdered phenolic binder, while the core mixture consisted of 87% expanded perlite and 13% liquid phenolic resin.

Mineral wool fibers were fed to the conveyor 30 of the upper and lower molding systems 83 and 84 at a rate of 1.12 kg per minute. Powdered phenolic resin was then fed to the conveyor 30 through station 32 at a rate of 0.084 kg per minute. This material was mixed together with the combing roller 33 and fed to shredders 34 of each mat forming zone. Except as noted below, the operating parameters were the same as those set forth in Example I.

The mineral wool binder compositions were fed to the respective matforming zones and felt on the open wire meshes 45 and 46 substantially as described in Example I. In this case, however, the air was extracted at different rates through the open wire meshes in the lower chamber; thus about 75% of the air was extracted through the lower mold wire mesh 45 of the zone 83 and about 25% was extracted through the upper mold wire mesh 46. The static pressure in each of these chambers was about 4.5 cm of water under atmospheric pressure, measured using a Dwyer meter.

The mats were converged at the respective nip openings 47, reinforced in compression zones 48, 40 treated with ramming devices 50 and anti-static devices 83 - 2 - 8 - direction 51 and then fed to the pre-compression rollers 98. After the bottom mat was transferred to the conveyor 90, a mixture of 23% liquid phenolic resin and 77% expanded perlite was deposited through the addition station 91 on the underlay at a rate of 4.3 kg per m2 (wet base). The core mixture was leveled with the scraper mold 93, combined with the top mat 94, and reinforced using the pre-compression rollers 98. The height of the pre-compression rollers at the entry point was about 3.3 cm above the conveyor 98, while the opening nip 99 had the height about 1.4 cm. This caused the exiting material to be extruded through the narrow pinch opening.

The thickness of the pre-assembled material obtained was about 1.8 cm.

The pre-compression served to impart to the resulting unpaved sheet a sufficient strength and edge formation so that the sheet could be conveyed by the following preheating and curing operations without loss of perlite from the core or damage to the composite material. After pre-compression, the plate was transferred to a TCD device such as that illustrated in Fig. 1? however, the top compressors were not used in the manufacture of the cored product. The purpose of the TCD device was to preheat the cored product with a downward flow of air, thus causing significant drying and curing of the core mixture while leaving the outer layers virtually uncured.

Thus, the temperature of the air in the TCD oven 30 remained below 149 ° C, a temperature at which the outer layer binder did not set. A period of about 2 minutes was used for preheating.

In the preheating step, the plate was cut into pieces and fed through an accelerator conveyor to a flat bed press. Due to the desired thickness of about 1.6 cm for the product, suitable stops were used in the press to ensure that no excessive compression occurred. The final cure temperature was 232 ° C, although variations between 40-177 ° C and 288 ° C could be used. Residence times in the press ranged from about 15 seconds to about 15 minutes, although a compression time of 1 minute and 30 seconds gave good results at 232 ° C. Optionally, a hand press could also be used for final curing 5 and pressing steps.

The obtained sheet had a total length of 1.6 cm and a density of 317 kg / m3. The thickness of each of the top and bottom skins was approximately 0.1 cm and the core thickness was 1.4 cm. The density of the outer layer was approximately 550 kg / m3, while the core density was approximately 252 kg / m3.

Example III

This example illustrates the manufacture of a pressed sandwich-like building board. The product 15 was manufactured in exactly the same manner as described in Example II up to the point where the uncured sheet emerges from the pre-compression rollers 98. In this case, the material was transported into the TCD device and air was passed through the sheet of the bottom to the top-20 side. Due to the reverse flow, the top compression means is set to lightly touch the top surface of the plate to prevent lifting or buckling due to the upward pressure of the airflow.

As a result of this treatment, curing occurred from the bottom of the plate upward and conditions were set so that the curing occurred within 1.6 mm - 6.4 mm of the top surface of the core material.

Following the preheating step, the plate was cut into pieces and fed to a flat bed press, the top plate of the press being provided with an insertion plate. The press was set so that the indentation plate penetrated only into the top uncured zone of the plate. As described for Example II, a temperature of 232 ° C was used for a residence time of 1 minute and 30 seconds. The density and basis weight values were almost the same as for the product of Example II.

Example IV

This example illustrates the manufacture 40 of a sandwich-like product with a thin moisture resistant δ 3 0 2 3 8 4 - 21 - high density interior. The total composition was as follows

Weight percent

Ingredients (solid base) 5 mineral wool 34 # 14 powdered phenolic binder 6.10 cement grade perlite 50.76 urea-formaldehyde resin 9.00

The outer layers consisted of 85% mineral wool and 15% powder-phenolic binder, while the core blend consisted of 85% cement grade perlite and 15% urea-formaldehyde resin.

The plate was manufactured almost as described in Example II, but because the desired final thickness was 4.76 mm, the stops in the pre-compression device were set at 4.56 mm. The obtained sheet had a density of 673 kg / m3 and a basis weight of 3.21 kg / m2.

The weight of the outer layers was 1.92 kg / m2.

Example V

This example illustrates the manufacture of a damage resistant board with wood fiber material. The total composition of the record was as follows:

Weight percent

Ingredients (solids base) 25 mineral wool 22.17 powdered phenolic binder 3.87 expanded perlite 48.10 de-sapwood fiber 11.08 liquid phenolic resin 14.78 30 This board was produced in the same manner as described in Example II to describe a product with a thickness of 1.59 mm and a density of 317 kg / m3. The total weight of the outer layers was 1.32 kg / m2. The presence of the wood fiber in this product had the effect of increasing the toughness of the board and reducing the effects of impact damage.

Example VI

This example, describing two alternative changes, further illustrates the technology of sequential curing. The basic procedure was similar to that used in Example II except that (1) the phenolic resin did not contain a hexamethylene tetramine curing agent and (2) the previously used core-5 binder was replaced with a starch powder.

The total composition of the plate, calculated on a dry basis, was as follows:

Weight percent

Ingredient (solids base) 10 mineral wool 24.21 powdered novalac phenol binder plus hexamethylene tetramine 1.82 expanded perlite 64.35 powdered starch binder 9.62 15 The outer layers consisted of 93% mineral wool and 7% binder based on the proportions of the above ingredients, while the dry core mixture consisted of 87% expanded perlite and 13% powdered starch.

The top and bottom layers were produced as described in Example II except that the powdery binder was added at a rate of 0.077 kg / minute due to the absence of the curing agent. Before adding the core mixture 25, it was wetted with water at a level of 19% based on the weight of the wet mixture. The wetted core mixture was then added through the core depositor 91 at a level of 4.8 kg / m2, the difference from the amount reported in Example II 30 being due to the added moisture.

After the added material was leveled with the scraper die 93, the composite materials were reinforced with the top mat using the pre-compression molds 98. The composite material was then transferred to a TCD device which, unlike the device in Example II was provided with a steam device. The steam device was placed at the entrance of the TCD device and consisted of a steam distribution pipe above the plate and a vacuum device below the 40 plate under the TCD conveyor.

83C 2 3 8 4

V

- 23 - '

As the plate passed in the TCD oven, the steaming device was used to draw steam into the plate at a rate sufficient to raise the temperature of the water in the core mixture above 82 ° C, where the starch gelled . The plate passed through the TCD device, where the core was dried and preheated in the usual manner. However, in this case it was possible to use temperatures higher than 149 ° C, because the binder in the outer layers did not contain the curing agent.

Following the gelling and drying steps, the plate was cut into pieces and fed into a spray booth. In this booth, a 10% solution of hexamethylene tetramide was applied to the top and bottom surfaces of the plate at a rate of 65 g / m2. The plate was then conveyed by an accelerator conveyor to a flat bed press and cured as described in Example II.

Under the action of the press, the hexamethylene tetramine disintegrated to release the formaldehyde curing agent, thereby setting the resin. The physical properties of the plate were almost the same as those measured for the product of Example II.

Pressed products can also be manufactured in the same manner and they provide the additional advantage of avoiding the partial pre-curing step as set forth in Example III. Thus, when the top and bottom layers are cured in the presence of the hexamethylene tetramine solution, the water that evaporates softens the starch core binder, allowing it to be deformed to the desired embossed shape.

The invention is not limited to the described embodiments, which can be modified within the scope of the invention.

Q 7 ~ o 3.

Claims (15)

Building board, characterized by a reinforced composite structure consisting of two non-woven webs (87.94) containing a binder and mainly inorganic fiber material, and a core layer (92) disposed between the non-woven webs (87.94) which contains a binder and a filler. 2. Plate according to claim 1, characterized in that the fiber material consists of mineral wool. Plate according to claim 1 or 2, characterized in that the core layer (92) contains expanded perlite. Plate according to any one of claims 1-3, characterized in that the composite structure 15 is hardened successively. 5. Plate according to claim 4, characterized in that the mixture of the core layer hardens at a temperature at which the binder in the non-woven webs remains virtually unhardened. 6. Sheet according to claim 4, characterized in that the binder in the nonwoven webs does not contain a curing agent, while the webs remain unhardened when the core layer mixture hardens, the web curing agent being added afterwards judging from the hardening of the jobs. Plate according to any one of claims 1-6, characterized in that the composite structure is differently compacted. 8. Method for forming a building board according to any one of claims 1-7, characterized in that a first mixture and a second mixture are prepared consisting of a binder and mainly inorganic fiber material, the first mixture is introduced in the upper zones of an upper mat forming zone and the second mixture in the upper zones of a lower mat forming zone, each mat forming zone comprising a first movable open wire mesh arranged in 83 0 2 3 8 4 ï - 25 - its lower zone and optionally a second movable open wire mesh arranged to converge with the first open wire mesh at a pinch opening therebetween, each mixture being introduced through a first opening so that it falls into and is dragged in a horizontal or upward direction airflow introduced through a second opening in each mat forming zone, the second openings having associated means for reg parts of the air passing therethrough, with the entrainment air being selectively extracted through the first open wire meshes and the optionally applied second open wire meshes to selectively deposit these mixtures thereon, the second openings and the optionally provided second wire meshes are arranged relative to the first 15 open wire meshes so that the mixtures deposited on these wire meshes are deposited almost evenly, the deposited mixtures being reinforced to form upper and lower webs, a core mixture consisting of a filler and a binder 20 is deposited on the bottom web, the resulting layered material being reinforced with the top web to form a composite structure and the composite structure being pressed and cured. 9. A building material forming apparatus according to any one of claims 1-7, characterized by (A) preparation means for preparing at least one mixture consisting of a binder and mainly inorganic fiber material, (B) a first and second mat forming zone, where each zone is connected with respect to the feed to a preparation agent for taking up a mixture therefrom and consists of (1) a first opening in its upper zone, which opening is provided with means for feeding the mixture therethrough mixture, (2) a second opening arranged therein such that air supplied through the second opening is directed horizontally or upwardly so that it crosses and entrains the mixture 40, the second opening being 8502284, - 26 - I Η ♦ means connected to control the direction of the air passing therethrough, (3) a first movable open wire mesh disposed in the lower zone of the mat forming zone, wherein the wire mesh exits the mat forming zone through a nip opening and optionally a second open wire mesh arranged to converge with the first open wire mesh at the nip opening, the optionally arranged second open wire mesh and the second opening arranged relative to the first open wire mesh so that the mixture is deposited almost evenly on the wire meshes, (4) means for adjusting the entrainment air in an adjustable manner through the open wire meshes to selectively deposit the mixture thereon, (5) means for moving the first open wire mesh and the optionally applied second open wire mesh to the nip opening and (6) means for stiffening the deposited material to obtain a nonwoven web, (C) means for converging the nonwoven webs formed by the first and second mat forming zones, and (D) means for reinforcing the webs and hardening the binders. 10. Device according to claim 9, characterized in that the optionally arranged second open wire mesh is replaced by a panel of non-conductive material. 11. Device according to claim 9, characterized in that the optionally arranged second open wire mesh is replaced by a closed wire mesh. 1¾. Device according to any one of claims 9-11, characterized in that air is extracted through the first open wire mesh using multiple suction means. 13. Device as claimed in any of the claims 9-11, characterized in that the means for controlling the air passing through the second openings (3 ή nή / Q v \ 3 sL 0 TT * - 27 - consists of a blade assembly. 14. Device according to any one of claims 9-12, characterized by ramming devices, anti-static devices or combinations thereof which facilitate the separation of the wire mesh webs. Device according to any one of claims 9-13, characterized in that the angle at the pinch openings is not less than about 20 ° and not more than about 55 °. Device according to any one of claims 9-15, characterized by means for applying the core mixture between the converging webs and means for strengthening the obtained material to obtain a composite structure. 15 o t λ λ .λ Λ f V - U ::, Ο 4