FI120794B - Process for making wood fiber insulation - Google Patents

Description

A method of making wood fiber insulation

The present invention relates to a process for the production of wood fiber insulation according to the preamble of claim 1.

According to such a method, a fibrous raw material consisting of wood fibers, cellulose or a combination thereof is mixed with adjuvants modifying its properties to form a fiber mixture, and the fiber composition 10 is formed into an insulating layer of the desired shape.

Fiberglass or wood fiber insulation, also called "cellulose" insulation, has long been known. It is a natural product with excellent heat insulating properties. from a treated wood raw material as disclosed in EP 0 694 094.

The properties of wood wool can be modified with additives and additives. Accordingly, excipients are known to be admixed with the mate-20 material, which render said insulation both "·" "irreversible and non-flammable. The most important of these excipients are boric acids, its salts and other compounds (borates, borax). • · · '* in the literature! many other substances have been proposed to be added, e.g. water glass, and various mi- • ·. mineral pigments such as fine silica and carboxymethylcellulose • ♦♦. *. / 25 • · • ·

Further, it is known to add thermoplastic fibers to wood fibers or to cellulosic fibers to bind wood fibers by heat treatment. • · ·. ···. (U.S. Patent 5,491,186).

Examples of other solutions in which the properties of wood fiber insulation have been modified include the fully refractory product known from EP 842 232, which is obtained by the addition of pigments and Al 2 (SO 4) 3 to the fibers. According to JP-A-95-159237, cellulose fibers can be made into panels by blending the fibers with a foamed phenolic resin and curing said mixture in a microwave heater. Hydrophilic wood fiber insulators using silicone compounds are also known in the art.

In all of the above solutions, it is essential that the excipients be well bonded to the wood fibers. Another important goal in the manufacture of wood fiber insulation is to make the material as unbending as possible so that it does not collapse over time. Preventing the latter phenomenon is particularly important when insulating layers of wood fibers are formed in vertical structures. By the known methods, both of these objectives have not yet been fully achieved.

The object of the present invention is to eliminate the drawbacks of the prior art and to provide a completely new solution for the manufacture of non-pressurized and solid insulators. In particular, it is an object of the invention to provide a wood fiber insulator that is inflatable to a desired insulating site and to which adjuvants that improve its fire and mold resistance are reliably fixed.

The invention is based on the idea that adjuvants for modifying wood fibers are attached to wood fibers with polyvinyl alcohol. From other connections, it is known that, for example, boric acid and its compounds are capable of rapidly gelling · · · ·; polyvinyl alcohol in aqueous solution. In the present invention, this property can be utilized in the manufacture of a fiber material by first blending the fiber material with excipients and thereby contacting the modified fiber blend with an aqueous solution of polyvinyl alcohol. For example, said solution may be sprayed onto a fiber mixture or mixed in an insulating object 0 · * or an aqueous solution of polyvinyl alcohol may be mixed with an insulating object in a stream of fiber immediately before it encounters the insulated site. Boo ····: Acid, borates and similar excipients then provide a rapid gelation of polyvinyl alcohol *: * ·: 30, whereby the polyvinyl alcohol solidifies and attaches to the fibers X while binding the excipients to them.

• ·· • * ··· t · * * 9 · «3

The aqueous solution of polyvinyl alcohol may be diluted with a water-soluble carbohydrate product or glycol or polyethylene glycol or the like with a high molecular weight hydroxyl group compound.

More specifically, the method according to the invention is essentially characterized by what is stated in the characterizing part of claim 1.

The solution of the invention achieves considerable advantages. Thus, according to our invention, non-pressurized, bonded wood fiber insulators suitable for the manufacture of panels can be manufactured, with the additional advantage that fiber modification aids, such as boric acid or borate compounds, remain long-lasting and reliable, even if completely wet.

Particularly advantageously, the invention can be utilized in the manufacture of insulating material panels, since the invention allows the insulating layer to be brought into the desired shape upon injection or immediately thereafter, and then adheres to that shape within a short period of time.

The invention will now be further explored by means of a detailed description.

The wood fiber fibers used in the invention, i.e. pulp, can be made by conventional means;; * ·: by tearing the paper and grinding it using, for example, a hammer mill, and mixing the fibers with a flame retardant, which kytemättömäksi. An example of the prior art is U.S. Patent No. 4,804,695, according to which the fibrous material X is ground either in wood or (refractory) paper X together with boric acid powder (14% boric acid in the fibers). * ·; · * Lift) using a hammer mill for grinding.

Preferably, however, the cellulose used in the present process comprises a fibrillated fibrous product obtained by grinding a suitable cellulose or ligno-cellulose-containing raw material. Additives are partially added before grinding. Reference is made in this connection to the solution according to EP 0 694 094. This product is marketed under the trade name EKOVILLA (supplied by Ekovilla Oy, 4

Kuusankoski). The most economical product is obtained by scrapping the recycled paper, but the products can also be made directly from wood or from unused pulp / paper. The milling is performed so as to produce an abrasive effect which leads to the fibrillation of the fibers to give a product similar to a fluff (i.e. pulp-5 tear). Thus, for example, refiners such as plate and conical refiners and similar refiners having rotary refining discs or blades are suitable. Particularly preferably, the refiners are provided with grooved or serrated blades.

The recycled paper used as the fibrous raw material may be woody, i.e., paper containing essentially only mechanical pulp, it may be wood-free or substantially chemical pulp, or it may be a combination thereof, such as LWC paper consisting essentially of mechanical pulp, among which is mixed with chemical pulp to reinforce the pulp. The recycled paper may further contain or be substantially free of fillers and pigments. All of the above raw materials are also referred to as "fibrous raw materials" in the context of the present invention.

To produce a suitable dielectric material, the fibrous raw material is ground to the desired fineness. By "desired fineness" is meant here the disintegration of the fibrous raw material into smaller parts. Generally, the raw material is disintegrated into flakes of about 0.1 to about 50 mm, preferably about 1 to about 10 mm.

• · * · · · · ·

During or after milling, the fiber raw material is mixed with auxiliaries, *: ··: in particular flame retardants such as boric acid [B (OH) 3] or its salts and esters, salts: /, da, urea, alkali metal salts of phosphoric acid etc. Of the borates, borax may be mentioned separately, i.e. disodium tetraborate as well as calcium salts of boric acid (bonocalcite, pandermite and boracite) and esters of boric acid such as triethoxyborane. In particular, · · · v: preferably borax, boric acid or a combination of these are used as the flame retardant. As stated in the above-mentioned EP patent, flame retardant - *: **! they can be mixed with pulverized pulp and cone grinders. In this case, it is advantageous to introduce part X of about 1/4 -1/2 X of flame retardants into the fiber material: * ♦. Before grinding anhydrous and part X about 1/2 to 3/4 X of anhydrous powder 9 9: ***: hat after. Of course, all flame retardants can be blended dry during fiber refining, but a greater amount of flame retardant is required to provide an initial fire protection of the material. The aim is to distribute the excipients as evenly as possible into the material.

The addition of the excipient provides a modified fiber raw material blend that is non-ho-5 juicy and non-flammable. According to the invention, polyvinyl alcohol is then added to the mixture, which binds the excipients to the fibers. Typically, polyvinyl alcohol is used in an amount of 0.01% to 10%, preferably 0.1% to 2%, particularly preferably about 0.15% to 0.5% by weight of the dry fibrous material. Polyvinyl alcohol (PVA) has previously been used as a binder in paper coatings. However, it has not been used in combination with boron compounds in paper coating technology because boron compounds provide very rapid gelling which reduces the controllability of the coating process. In the present invention, on the other hand, rapid gelling has a considerable advantage, since the fibrous material to be bonded together does not have time to collapse.

PVA is added to the modified (i.e., excipient-containing) fiber material during the formation of the dielectric layer. This means that the dry fiber stream and the aqueous PVA solution are combined just before or at the point of insulation. Adding PVA too soon causes problems with fiber injection and easily clogs nozzles and other devices.

M * • · · • · · ·

Preferably, the polyvinyl alcohol is added to the fiber mixture in an aqueous solution, '· *' *! to which may also be added water-soluble cellulose derivatives. The aqueous solution is generally dilute with respect to PVA, most preferably the concentration of PVA is from about 0.1% to about 10% by weight, preferably from about 1% to about 5% by weight. PVA can be blended into the fiber at room temperature or at elevated temperature.

When water is a solvent for both PVA and borate or boric acid or their combination: *: **: and when the water begins to evaporate, the boron compounds are always slightly concentrated 30 on top of a PVA layer and so on provides excellent protection against mold: * ·. ·. PVA, in turn, binds boron compounds so that they do not migrate with the moisture and · · · · · · and do not drop away from the insulation as loose particles. PVA does not dissolve in water at all except at> 80 ° C, and once dried, PVA also remains in the insulation under normal building conditions. By introducing flame retardants and / or other salts in a partially anhydrous state into the mixture, the bonding and crystallization of the crystal water binds the fibrous mass in place, as stated in the above-mentioned EP 0 694 094. The combination effect of PVA and boron compounds greatly increases the binding effect and can be used simultaneously.

Gelation of PVA with boric acid and its salts has been described above. It should be noted that many other excipients, such as those containing aluminum and zirconium, have a similar effect. Therefore, zirconium salts can especially be used for the gelation of PVA, since they give an even stronger gel than the boron compounds. These agents can also be used simultaneously.

Other water-soluble functional chemicals, such as more potent mold inhibitors and insecticides such as copper sulfate and tin compounds, can be further mixed with the insulator. Other additives, such as soda ash and anhydrous gypsum, can be used, all of which have the advantageous ability to bind excess water.

The amount of excipients added may vary widely; typically, a total of about 0.01% to about 50% of the dry weight of the fibers is added to the fibers. Suitable addition amounts for boron compounds are from about 0.1 to about 20% by weight. Generally, the boron compounds comprise at least 10%, preferably at least 30%, and particularly preferably at least 40%, of the total amount of additional excipients.

Carboxymethylcellulose (CMC) has also been used as a binder in our experiments, which gave a surprising result in combination with PVA. According to our experience, in this way, the adhesion of the binder combination to the environment, such as wood and concrete, improved markedly.

• · *: ··: 30 The better interaction between CMC. and PVA. seems to be due to the fact that CMC slightly slides down the gelation rate of PVA as a diluent and thus slightly more • · · * ··. time to adhere to desired surfaces.

The M * 7 CMC is also cheaper than PVA and thus user friendly. The delayed gelation also gives time for diffusion of fire and mold inhibitors as the surface dries further.

Corresponding other water soluble cellulose derivatives work in the same way. These include: hydroxyethylcellulose (HEC) and methylcellulose (MC) and its ether derivatives, such as hydroxyalkyl ethers, e.g., hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), and hydroxybutylmethylcellulose (HBM).

10

In general, the amount of water-soluble cellulose derivative that may be used is at least 5%, preferably at least 10%, and particularly preferably about 25-75% of the total amount of polyvinyl alcohol and cellulose derivative.

The aqueous solution of the polyvinyl allyl lifter can be diluted with a water-soluble carbohydrate product such as starch or cationic starch in an amount of at least about 1%, preferably 10-50% by weight of PVA. The PVA solution can also be diluted with glycol or polyethylene glycol or a corresponding water-soluble, high molecular weight hydroxyl group compound.

As mentioned above, the wood fiber insulation (cellulose) treated according to the invention is particularly suitable for use in the production of injection molded insulators. As used herein, the terms "dielectric" and "dielectric layer" are used interchangeably with one another. The dielectric layer can be of any shape and the term "layer" in this context means that the finished dielectric has overlapping and adjacent fibers in every dimension.

··· • · · · · ·

According to a preferred embodiment of the invention, the fibrous wool is treated as a fluff *: * ·: e.g. by blowing the fibers along the pipeline to the application. The inflatable mass Ί * ·: 30 comprises wood fibers treated with boric acid and / or borate compounds and possibly other auxiliaries. The wood pulp is then mixed prior to or at the latest with the application of dilute aqueous PVA. The mixing may conveniently be performed in a mixing nozzle which combines the wood fiber pulp pipeline with an aqueous PVA solution. The resulting mixture is blown 8 surface or panel forming molds or insulating cavities.

According to a particularly advantageous embodiment, the mixing nozzle is constructed such that mixing of the pulp and the aqueous PVA solution occurs only on the way from the nozzle to the application. As such a mixing nozzle can be used an apparatus solution which includes, for example, concentricly arranged nozzles for wood fibers and an aqueous solution of PVAZ, whereby the outlet ends of the nozzles are in close contact with each other. The arrangement may be, for example, such that wood fiber and air are blown in the inner tube and, through the water nozzles or nozzle ring arranged immediately outside, an aqueous solution of PVA. The arrangement can also be the other way around.

With the device shown in the test plant, effective fiber insulator binding was achieved with amounts as low as 0.25% by weight of air-dry cellulose wool.

15

According to a particularly important embodiment, the invention is used for providing wooden or concrete elements with a non-compression and solid thermal insulation layer. Such elements can be used, for example, in wall surfaces of a building.

20 In this application, the product prepared as above is sprayed on the edge. Sat and rear panel. After spraying, the product is • ·: **. · Leveled. The alignment is made, for example, by a blade rotating at a sufficient speed, * · ·: * ··, which tears the fibers out of the pulp and has a minimum circumferential velocity of 5 m / s. The separable fibers can be blown back into the blowing nozzle of the fresh thermal insulator. Preferably, the nozzle in question then has a vacuum, i.e. a suction-forming tap for recirculation, which accelerates the velocity of the air: v. After leveling, the PVA + additive solution is preferably sprayed onto the surface of the product and on the edges to which a moisture barrier is attached by means of this adhesive.

* • ·: ··: 30 To dry the product, a suitable amount of drying agent may be sprayed on the surface of the product prior to equalization, which will bind water or crystal water and reduce • ·· * •. ···. to a desired level the relative humidity of the contents of the thermal insulation element. For this use, the anhydrous anhydrous salts are e.g. calcium sulfate, magnesium sulfate, sodium carbonate, sodium bicarbonate or a suitable mixture thereof. An example of other desiccants is silica gel.

In connection with the invention, a blowing apparatus has been developed, whereby the blowing of pulp wool into the building elements can be made particularly smoothly. This apparatus comprises a blow nozzle which is arranged to move back and forth from the edge of the element to the edge and at the same time steadily forward. According to our invention, this device must be constructed in such a way that there is no excess material at the pivot point of the reciprocating movement. The use of linear motion would increase the amount of 10 blown on the edges by almost twice the amount of the center section.

We have found that if the blowing nozzle is controlled by an elliptical actuator having at its pivot points the control ellipse at the extreme position of either of the foci when the nozzle is in the flip position, accelerated movement near the flange can be reduced thereby reducing asymmetric insulating material accumulation. The material flow from the nozzle is reduced to evenly distribute the material.

The reciprocating motion of the nozzle assembly is controlled by a rotating elliptical orbit so arranged that, at and around the pivot point, the nozzle assembly travels no-20 more than in the center. The best result is obtained with an ellipse having a ratio of axes between a / b = 1.5 to 2.5, preferably 1.75 to 2.0.

• · • 1 · • · · • • • • • • • • • • • • • • • • • • • •

• M

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ·

IM

• • • • • • • • • • • • 1

Claims (11)

A process for making a wood fiber insulation material from a raw material consisting of wood fiber, cellulose or a combination thereof comprising: admixing excipients to modify the properties thereof, - binding the excipients to the raw material with polyvinyl alcohol, and - the insulating layer is formed from the modified raw material, characterized in that - the polyvinyl alcohol is fed in an aqueous solution with added starch, cationized starch, glycol or polyethylene glycol, first the adjuvants are mixed with the polyvinyl alcohol, 15 during the formation of the insulating layer. Process according to Claim 1, characterized in that boric acid and / or its salts or esters, which act as flame retardants and mold inhibitors, are used at least in part. : \ 20 • Il fcV : * · *; The process according to claim 1 or 2, wherein the wood fiber insulation is prepared by injection of boric acid and / or its compounds *: ··: the raw material is fed by pipeline to an object, characterized in that the polyvinyl alcohol is mixed with boric acid and / or wood containing its salts: ", * · * 25 fiber insulation on the way to or from the object to be isolated. ··· v 1 The process according to any one of the preceding claims, characterized in that the polyvinyl alcohol is used in an amount of 0.1 to 2% by weight of the dry fibrous material, preferably: 0.15 to 0.5%. ·: * ·: 30 A method according to any one of the preceding claims, characterized in that the wood fiber insulation is sprayed onto a building element with edges and backside and, after spraying, the surface of the product is leveled. Method according to Claim 5, characterized in that, after blowing into the element, the product is leveled with a rotating cutting blade of sufficient speed, which tears the fibers out of the pulp and has a minimum circumferential velocity of 5 m / s. 5 Method according to Claim 6, characterized in that the fibers to be separated in the alignment are blown back into the blowing nozzle of the fresh thermal insulator. A method according to any one of the preceding claims, characterized in that, after leveling the surface of the wood fiber insulator, a solution containing polyvinyl alcohol and any additives is applied to the surface of the product and to the edges to which the moisture barrier is attached. Method according to one of Claims 6 to 8, characterized in that, prior to any surface treatment with a polyvinyl alcohol solution, the product is sprayed with a desiccant which binds crystal water or crystal water and reduces the relative humidity of the thermal insulation. "· 20 : * · *; Process according to Claim 9, characterized in that an anhydrous salt such as calcium sulfate - *: *, magnesium sulfate, sodium carbonate, sodium bicarbonate or a mixture thereof, or silica gel - is used as the spray drying agent. • · «'· * 25 ··· w A process according to claim 1, characterized in that the starch * · v; The amount of lysine or cationic starch used is at least about 1%, preferably ··· 10-50%, of polyvinyl). • · ·: · *: 30 • · · · · · · · · · · ···