FI109709B - A method of making wood fiber insulation - Google Patents

Description

1 109709

A method of making wood fiber insulation

The present invention relates to a process for making 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.

Wood fiber wool or wood fiber insulation, also called "cellulose11" insulation, has long been known. It is a natural product with excellent thermal insulation properties. Wood wool is made from a fibrous raw material, such as mechanical pulp, recycled fibers or chemical pulp. Particularly preferably, wood fiber wools are made from a wood raw material processed by treatment with a fibrillating wool, as disclosed in EP 0 694 094.

The properties of wood wool can be modified with additives and additives. Thus, excipients are known to be admixed with the material, 20, which make said insulating as well. unbreakable and unbreakable. The most important of these excipients is boron ·. . acid and its salts and other compounds (borates, borax). The literature insulates ·. Many other substances have been proposed to be added to the. water glass, and various mineral pigments such as fine silica and carboxymethylcellulose::: 25

Further, it is known to include thermoplastic fibers among wood fibers or cellulosic fibers, which are capable of bonding wood fibers by heat treatment (U.S. Patent No. 5,491,186).

; ; 30 Examples of other solutions in which the properties of wood fiber insulation have been modified include the fully refractory product known from EP application 842 232: a product obtained by adding pigments and Al 2 (SO 4) 3 to fibers. According to JP application 95-159 237, cellulose fibers can be made into panels by mixing the fibers with a foamed phenolic resin and curing said mixture in a microwave oven. 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 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 object and to which its auxiliary agents for improving 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. Other connections are; It is known that, for example, boric acid and its compounds are capable of rapidly gelling polyvinyl alcohol in an aqueous solution. In the present invention, this property can be utilized in the manufacture of a fibrous material by first mixing the fibrous material with excipients and thereby contacting the modified fiber mixture with an aqueous solution of polyvinyl alcohol. For example, said solution may be sprayed onto the fiber mixture or mixed in the object to be isolated, or the aqueous solution of polyvinyl alcohol may be mixed with the fiber stream injected into the object immediately prior to contacting the object to be isolated. Boolic acid, borates, and the like, then cause a rapid gelation of the polyvinyl alcohol 30, whereby the polyvinyl alcohol solidifies and attaches to the fibers: * \. while binding the excipients to them.

3, 109709

The combined use of borax and / or boric acid and polyvinyl alcohol for fiber binding is known in the art from WO-A-9705205, US-A-5,853,802 and AU-A-598414 and Derwent Abstract, 1979-62394B.

5

In the context of the present invention, it has been found that the gelation of polyvinyl alcohol can be retarded to provide slightly more time by bonding to the desired surfaces by feeding polyvinyl alcohol in an aqueous solution of water-soluble cellulose derivative . The excipients are first mixed with the raw material, followed by the addition of an aqueous solution of polyvinyl alcohol to which a water-soluble cellulose derivative has been added.

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

The solution according to the invention provides considerable advantages. Thus, according to our invention, non-pressurized and suitable panels can be manufactured; 20, bonded wood fiber insulators, with the additional advantage that adjuvants used for fiber modification, such as boric acid or borate compounds, remain long and reliable in the insulation, even if it is sometimes completely wet.

It is particularly advantageous to utilize the invention in the manufacture of insulating panels because, by means of the invention, the insulating layer can, upon injection or immediately thereafter, be brought into the desired shape and then adhered to it within a short period of time.

The invention will now be described in more detail with reference to the detailed description.

The wood fiber fibers used in the invention, i.e. pulp, can be made by conventional techniques by tearing paper and grinding it with, for example, a hammer mill and blending flame retardant with fibers to render the insulation non-combustible and non-flammable. An example of the prior art is U.S. Patent No. 4,804,695, according to which the fibrous material X is ground either wood or (waste) paper X together with boric acid powder (14% boric acid by weight of the fibers) using a hammer mill.

5

Preferably, however, the pulp used in the present process comprises a fibrillated fibrous product obtained by grinding a suitable cellulose or lignocellulosic feedstock. Additives are partially added before grinding. Reference is also made in this connection to Solution 10 of EP 0 694 094. This product is marketed under the trade name EKOVILLA (supplied by Ekovilla Oy, Kuusankoski). The most economical product is obtained by pulping recycled paper with this technique, but the products can also be made directly from wood or from unused pulp / paper. The milling is carried out so as to produce a grinding effect which results in the fibrillation of the fibers to give a product similar to a fluff (i.e. pulp-15 tear). Thus, for example, refiners such as plate and cone refiners and similar refiners having rotary refiner 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 having essentially only mechanical pulp, it may be wood-free or substantially chemical pulp, or it may be a combination of these, such as LWC paper consisting essentially of mechanical pulp. chemical pulp has been blended to form the reinforcement mass. The recycled paper may further comprise or be substantially free of fillers and pigments. All of the above: The raw materials used in this invention are also referred to as "fibrous raw materials".

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 the milling, the fiber raw material is mixed with excipients, in particular flame retardants such as boric acid [B (OH) 3] or its salts and esters, soda, urea, alkali metal salts of phosphoric acid, etc. The borates may be specifically mentioned as borax or disodium tetraborate. as well as calcium salts of boric acid (borocalcite, pandermite and boracite) and esters of boric acid such as triethoxyborane. Particularly preferably, borax, boric acid or a combination thereof is used, at least in part, as a flame retardant. As stated in the aforementioned EP patent, flame retardants can be blended into the pulverized pulp by plate and cone grinders. In this case, it is preferable to introduce part X of about 1/4 -1/2 X of the flame retardants into the fibrous material before milling in anhydrous form and part X of about 1/2 to 3/4 X after milling in crystalline water. 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 flame retardant to 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 which is non-moldy 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 dry fibrous material. Polyvinyl alcohol (PVA) is early; . used as a binder in paper coatings. However, it has not been used in combination with boron compounds in paper coating technology because the boron: 20 compounds provide very rapid gelling which reduces the controllability of the coating process. The present invention, on the other hand, has the considerable advantage of rapid gelation, since the fibrous material to be bound together does not have time to collapse.

'25 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 only at the point of insulation. Adding PVA too early causes problems with fiber injection and easily clogs: nozzles and other equipment.

"* ·: 30

According to the invention, polyvinyl alcohol is added to the fiber mixture in an aqueous solution to which also water-soluble cellulose derivatives have been added. The aqueous solution is generally dilute with respect to PVA, most preferably the concentration of PVA is from about 0.1 to about 10 670709% by weight, preferably from about 1 to about 5% by weight. PVA can be blended into the fiber material at room temperature or at elevated temperature.

When water is a solvent for both PVA and borate or boric acid or a combination thereof, and when the water begins to evaporate, the boron compounds are always slightly concentrated on the PVA layer to provide excellent protection against mold. PVA, in turn, binds boron compounds so that they do not migrate with moisture in the insulation and do not fall off the insulation as loose particles. PVA does not dissolve in water at any temperature other than> 80 ° C and thus 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 boo 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 be used in particular for gelation of PVA because 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.

: j: The amount of excipients added can 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 excipients added.

7 109709

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

5 Better interaction between CMC and PVA seems to be due to the fact that CMC as a diluent slightly slows down the gelation rate of PVA and thus gives a little more time to bond to the desired surfaces.

10 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 15 may be mentioned e.g. hydroxyethylcellulose (HEC) and methylcellulose (MC) and its ether derivatives such as hydroxyalkyl ethers, e.g., hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC) and hydroxy. sibutylmethylcellulose (HBMC).

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

An aqueous solution of polyvinyl alcohol can be diluted with a water-soluble carbohydrate; 25 products, such as starch or cationic starch, in an amount of at least about 1%, preferably 10 to 50%, by weight of PVA. The PVA solution may also be: diluted with glycol or polyethylene glycol or a similar 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 sprayable insulators. As used herein, the terms "dielectric" and "dielectric layer" are used interchangeably. The insulating layer may be of any shape and "layered" is used herein to mean that the finished insulator has overlapping and adjoining fibers in every dimension.

According to a preferred embodiment of the invention, the fibrous wool is treated as a fluff 5, for example by blowing the fibers along the pipeline to the application. The inflatable pulp then comprises wood fibers treated with boric acid and / or borate compounds and possibly other auxiliaries. The wood pulp is then mixed with the diluted aqueous PVA solution before or at the latest. Advantageously, mixing can be performed in a mixing nozzle, where the wood-pulp pulp line is connected to an aqueous PVA solution line. The mixture thus obtained is blown onto an insulating surface or into panel-forming molds or insulating cavities.

According to a particularly preferred 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 a device solution which includes, for example, concentricly arranged nozzles for wood fibers and an aqueous solution of PVA, the nozzle outlet ends being in close prox. . in tact with each other. The arrangement may, for example, be such that the inner tube • is blown. 20 through the water nozzles or the nozzle ring arranged directly outside it, the aqueous solution of PVA. Still life can 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.

; 25

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

....: 30 In this application, the product prepared as described above is injected into a building element with edges and backside. After spraying the product is leveled. The alignment is made, for example, by a cutting blade rotating at a sufficient speed, which tears the fibers out of the pulp and has a minimum peripheral speed 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 taper for recirculation, which accelerates the air velocity. 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.

5

Prior to leveling, the product may be sprayed with a suitable amount of desiccant, which binds crystal water or crystal water and reduces the relative humidity of the contents of the thermal insulation element to the desired level. Anhydrous anhydrous salts for this use include e.g. calcium sulphate, magnesium sulphate, sodium carbonate, sodium bicarbonate or a suitable mixture thereof. An example of other desiccants is silica gel.

In connection with the invention, a blowing device has been developed, whereby the blowing of cellulose wool into the building elements can be made particularly smoothly. This apparatus comprises 15 blowing nozzles arranged to move reciprocally from edge to 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 motion. The use of linear motion would increase the amount of insulation blown on the edges by almost twice that of the center section.

A: 20

We have found that if the blowing nozzle is controlled by an elliptical actuator in which the control ellipse at the pivot points is in the extreme position of either of the foci when the nozzle is in the flip position, the movement near the flank can be accelerated and thereby reduce asymmetric insulating material accumulation. Material • '-: To distribute 25 alpha evenly, material flow from the nozzle is reduced.

The reciprocating motion of the nozzle assembly is controlled by a rotating ellipse, so ...: arranged that, at and around the inflection point, the nozzle assembly passes no-::: more than in the center. The best result is obtained with an ellipse, where the ratio of the axes ·: ··: 30 is between a / b = 1.5 ... 2.5, preferably 1.75 ... 2.0.

Claims (14)

10 109709 Claims: A process for making a wood fiber insulation material from a raw material consisting of wood fiber, cellulose or a combination thereof, comprising: the modified raw material is formed into an insulating layer, characterized in that: followed by addition of an aqueous solution of polyvinyl alcohol to which the water-soluble cellulose derivatives have been added to the modified raw material when forming a 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 partially as excipients. A process according to claim 1 or 2, wherein the wood fiber insulation is prepared by injection of a boron-containing and / or compound-containing: raw material into a pipe-insulated object, characterized in that the polyvinyl alcohol is mixed with the boric acid and / or its salts isolated object or object. 'J'; A 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%, preferably 0.15 to 0.5% by weight of the dry fibrous material. j i Process according to any one of claims 1 to 4, characterized in that carboxymethylcellulose, hydroxyethylcellulose, methylcellulose or hydroxyalkyl ether such as hydroxypropylmethylcellulose, hydroxyethylmethylcellulose or hydroxyethylcellulose is used as the water-soluble cellulose derivative. 5 Process according to one of Claims 1 to 5, characterized in that the amount of water-soluble cellulose derivative is 25-75% of the total amount of polyvinyl alcohol and cellulose derivative. Process according to one of Claims 1 to 6, characterized in that a carbohydrate product such as starch or cationic starch is preferably incorporated in an aqueous solution of polyvinyl alcohol, preferably in an amount of 10-50% by weight of the PVA. Process according to one of Claims 1 to 7, characterized in that glycol, polyethylene glycol or similar water-soluble, high molecular weight substance containing hydroxyl groups is incorporated in the aqueous solution of polyvinyl alcohol. Method according to one of the preceding claims, characterized in that '. 20 that the wood fiber insulation is sprayed onto a building element with edges and backside: · after spraying, the surface of the product is leveled. A method according to claim 9, characterized in that, after blowing into the element, the product is made to rotate at a sufficient speed. i 25 cutting blades, which tear the fibers off the pulp and have a minimum peripheral speed of 5 m / s. A method according to claim 10, characterized in that ·: ·. In this process, the fibers to be separated are blown back to the blasting of fresh thermal insulation ....: 30 blowing nozzle. 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 possible additives is applied to the surface of the product and to the edges of which the moisture barrier is fixed. A method according to any one of claims 10 to 12, characterized in that a drying agent which binds crystal water or crystal water and reduces the relative humidity of the thermal insulation is sprayed on the surface of the product prior to any surface treatment with polyvinyl alcohol solution. Process according to Claim 13, 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. 13 109709