FIELD
[0001] The present invention relates to improved acoustic structures and natural fibrous
acoustic coatings on porous building materials.
BACKGROUND
[0002] When planning and implementing structures, more and more attention is paid to the
acoustics of rooms, offices and other spaces. Naturally, functioning acoustics are
a prerequisite, for example, in concert halls, but, the acoustics also have significant
impacts on the levels of satisfaction, work efficiency, and even human health, for
example, in homes, schools, and workplaces. Since structural solutions cannot be selected
on the terms of acoustics alone, different acoustic elements or acoustic surfaces,
which are installed in the spaces and on their surfaces after the actual construction
stage, are needed.
[0003] A primary requirement for the functioning of the acoustic surface or element, naturally,
is that it has suitable acoustic properties. Generally, this signifies a sound absorption
that is sufficiently strong or has a frequency response of a suitable form. On one
hand, since the acoustic elements and surfaces are structures that remain in sight,
their architectural image should also be suitable for their environment and the other
surfaces of the space. The thickness of the panel or surface should remain within
reasonable limits, which, on the other hand, is inconsistent with the high requirement
of sound absorption. Naturally, the acoustic elements or surfaces should also fulfil
the criteria of purity which is set for the surface materials of interiors, and they
should also have mechanical and physical properties that are suitable for their environment
of use. Similarly to other structural elements, the requirement of considering environmental
aspects, to an increasing extent, also applies to the acoustic surfaces and elements
with respect to the manufacture and recyclability of the materials, for example.
[0004] The most common commercially available, ready-made acoustic elements include mineral
wool-based (fibreglass or rock wool-based) acoustic panels. On the sides of these
which remain in sight, the surface of the mineral wool is coated, for example, with
paper, plastic, fabric or glass fleece. Being relatively light components, these acoustic
elements, which are based on insulating wool panels, are simple to install, for example,
on the ceiling or walls of the space that is to be provided with sound absorption,
either as separate elements or as an unbroken surface. They can also be formed into
acoustic planes that are lowered down from the ceiling, for example.
[0005] For the coating of walls, ceilings or the like in different interiors, various fibre-based
coating compounds are also known, which are sprayed or applied in another way and
which provide a mechanical surface structure that is more elastic and durable than
glass and rock-based coatings, and which can also contribute to the acoustics of the
premises.
[0006] For example, the specifications
FI 95041 and
WO 2007/063178 disclose natural fibre-based coatings that are sprayed when mixed with water, or
applied in a similar manner and hardened through drying. The fibre of the coating
compound of the specification
FI 95041 comprises fine cellulose fibre. In the solution of the specification
WO 2007/063178, in addition to the fibre material and the binder, the compound includes particle-like,
typically mineral-based fillers, by means of which the surface of the coating becomes
smooth and which can adjust the acoustic properties of the coating.
[0007] Typically, the fibre-based coatings are attached to the desired acoustic properties
requiring surface by binders.
[0008] US 3,044,919 relates to a surfacing or facing construction particularly adaptable for application
on wall and ceiling areas or surfaces and to a method or system of applying the surface
of facing to an area, the surfacing or facing construction embodying a thin mat, layer
or sheet of mineral material adapted to be adhesively joined to the surface or area
to be finished. However, it does not disclose natural fibrous acoustic coatings on
cinder block, nor especially fixing the coating to a desired surface without binders.
[0009] GB 358,995 relates to improvements in sound-absorbing materials adapted to be used in buildings,
enclosures and the like. It discloses an acoustic composition having desirable sound-absorbing
properties of various fibrous materials combined with the advantages with respect
to durability and appearance of plastic or stone-like materials. The composition comprises
a layer of a resilient sound-absorbing material or fibre-board having a hard facing
or protective layer of granular particles which has pores or openings leading into
the sound-absorbing material. The publication is however silent on natural fibrous
acoustic coatings on cinder block, nor especially fixing the coating to a desired
surface without binders.
[0010] Document
RU2369495 C2 discloses an acoustic structure with the features of the preamble of claim 1.
[0011] Thus, there is a need for improved acoustic structures and reverberation reducing
surfaces utilizing natural fibrous acoustic mass.
SUMMARY OF THE INVENTION
[0012] The invention is defined by the features of independent claim 1. Preferred embodiments
of the invention are defined in the dependent claims.
[0013] According to an aspect of the present disclosure, there is provided an acoustic structure,
such as a wall, made of a porous background material and coated with a natural fibrous
acoustic material.
[0014] According to another aspect of the present disclosure, there is provided an acoustic
structure, such as a wall, made of porous incompressible or load-bearing background
structures and coated with a natural fibrous acoustic material, wherein the acoustic
coating is attached to the surface of the background structure without using any binders.
The background structure neither needs to be felted before applying the acoustic coating.
[0015] This and other aspects, together with the advantages thereof over known solutions
are achieved by the present invention, as hereinafter described and claimed.
[0016] The acoustic structure of the present invention is characterized by what is stated
in the characterizing part of claim 1.
[0017] Considerable advantages are obtained by means of the invention. For example, the
natural acoustic coating can be applied, for example by spraying, straight on to a
surface of a wall made of e.g. cinder blocks without any ground work, yet providing
a plain surface. In addition, the natural fibrous acoustic coating according to the
present invention is applicable to the surface of the wall material the without using
any binders. Furthermore, natural fibrous coatings are not harmful for consumers and
they enable moisture vaporization from the below structures.
[0018] Next, the present technology will be described more closely with reference to certain
embodiments.
EMBODIMENTS
[0019] The present technology provides coatings on porous background structures that improves
the acoustic properties of premises and reduces the drawbacks of the known solutions.
The present technology is particularly suitable for reducing reverberation in inner
acoustics of premises.
[0020] One purpose of the invention, in particular, is to provide an acoustic structure,
which is formed by utilising a natural fibrous coating composition, which is particularly
suitable for the purpose and which provides effective sound absorption, and from which
no significant amounts of dust or other particles come off, even after drying.
FIGURE 1 is a photo of a cinder block coated with the natural fibrous acoustic coating
according to the present invention.
FIGURES 2 and 3 are schematic drawings of a porous coating consisting of natural fibres
on top of a porous (Fig.2) and perforated or micro-perforated (Fig. 3) background
structure.
FIGURE 4 is a diagram showing acoustic properties of another possible acoustic structure,
wherein porous cinder blocks (thicknesses 90 mm and 125 mm) were coated with approximately
6 to 8 mm fibrous coating according to the present invention.
FIGURE 5 is a diagram showing improvement of the acoustic properties of perforated
metal when coated with the fibrous 8 mm thick coating according to the present invention.
Diameter of the perforation holes is approximately 5 mm.
[0021] The present invention is based on a combination of a porous background material and/or
structure and a natural fibrous coating on at least one surface of the porous background
material and/or structure.
[0022] One aspect of the present invention is a combination of a porous background structure
and an acoustic coating, wherein the acoustic coating is made of natural fibrous matter
and is applied on at least one surface of the porous background structure, and wherein
the natural fibrous matter forms a plain network on top of the holes in the surface
of the porous background.
[0023] Herein the term "porous background structure" is intended to comprise all materials,
where to holes have been made or formed during the production of such structure. Porous
background structure may therefore be for example a building material such as cinder
block, or a perforated or micro-perforated structure consisting of for example wood
or metal.
[0024] The acoustic structure can be for example an acoustic element, or a wall structure,
or any other structure, which requires sound-proofing and is preferably made of a
porous building material, such as a cinder block.
[0025] According to one embodiment of the present invention, the natural fibrous matter
is plant or plant-based fibre, such as cellulose, flax, cotton or hemp fibre, or animal-based
fibre, such as silk or wool-based fibre, or a mixture of such fibres. The acoustic
coating comprises the natural fibrous matter 20-100% of the dry-matter mass of the
acoustic coating.
[0026] In one embodiment of the present invention the coating has a thickness between 1
to 30 mm, preferably between 3 to 10 mm.
[0027] In one embodiment of the present invention, the acoustic coating further comprises
0-80% of mineral filler from its dry matter mass, preferably mineral silicate, mineral
sulphate or mineral carbonate, most preferably kaolin.
[0028] In a further embodiment of the present invention, the coating comprises a fire retardant
and an anti-rot agent, selected from a group of boron-based substances, such as boric
acid or borax or a mixture thereof, hydroxides, such as aluminium or magnesium hydroxide
or a mixture thereof, or absorbing agents, such as talc or calcium carbonate or a
mixture thereof, most preferably boric acid or borax, particularly a mixture thereof,
in an amount of 8-25% by weight of the dry matter at the most.
[0029] In one embodiment of the present invention, the structure below the acoustic coating,
such as a cinder block, has a density of 300 to 2200 kg/m
3 and a pore size preferably of 1 to 16 mm. The thickness of the structure varies based
on the used building material, but should be at least 2 mm, more preferably at least
5 mm.
[0030] In a further aspect of the present disclosure, the porous background structure underneath
the natural fibrous acoustic coating is incompressible. In another embodiment of the
present invention, the porous background structure is a load-bearing structure.
[0031] In one aspect of the present disclosure, the background structure underneath the
natural fibrous acoustic coating is a perforated or micro-perforated structure, which
alone without the coating provides very poor acoustic properties. Similarly, the background
structure may be any other kind of porous or perforated structure having holes, on
top of which the natural fibrous coating matter forms a plain network.
[0032] In accordance with the present invention, the acoustic coating does not contain any
binders for binding into the surface of the porous background. This embodiment is
achieved by the network of the natural fibrous matter formed on top of the holes in
the porous background. Porous acoustic coating can thus be prepared without binders
by utilizing particles of different size scales, for example by combining cellulosic
fibres with micro-fibrillated or nano-fibrillated cellulose.
[0033] One aspect of the present invention is that because of the fibre network on top of
the holes in the surface of the porous background, the surface can be made plain.
[0034] Another aspect of the present invention is that the porous background structure does
not need to be felted before applying the acoustic coating, which reduces the process
steps and costs as well as provides easier yet effective acoustic solutions. The present
invention also provides material savings for example in binder and seaming materials.
[0035] Reference throughout this specification to one embodiment or an embodiment means
that a particular feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the present invention. Thus,
appearances of the phrases "in one embodiment" or "in an embodiment" in various places
throughout this specification are not necessarily all referring to the same embodiment.
Where reference is made to a numerical value using a term such as, for example, about
or substantially, the exact numerical value is also disclosed.
[0036] As used herein, a plurality of items, structural elements, compositional elements,
and/or materials may be presented in a common list for convenience. However, these
lists should be construed as though each member of the list is individually identified
as a separate and unique member. While the forgoing examples are illustrative of the
principles of the present invention in one or more particular applications, it will
be apparent to those of ordinary skill in the art that numerous modifications in form,
usage and details of implementation can be made without the exercise of inventive
faculty, and without departing from the principles and concepts of the invention.
Accordingly, it is not intended that the invention be limited, except as by the claims
set forth below.
[0037] The verbs "to comprise" and "to include" are used in this document as open limitations
that neither exclude nor require the existence of also un-recited features. The features
recited in depending claims are mutually freely combinable unless otherwise explicitly
stated. Furthermore, it is to be understood that the use of "a" or "an", that is,
a singular form, throughout this document does not exclude a plurality.
INDUSTRIAL APPLICABILITY
[0038] The present invention is applicable to for example walls and other kinds of structures
comprising porous or perforated background structures in for example buildings, providing
acoustic solutions mainly to the inner acoustic needs of the space formed by such
structures.
EXAMPLE
[0039] Preparation and characterization of the natural fibre coated cinder block structure
as illustrated in Figure 1 is herein described. Coating was be prepared by dissolving
or dispersing additives, such as binders, thickeners and fire retardants, into a solvent
and dispersing the fibres by mechanical mixing to form a suspension. The coating was
applied onto the surface of the cinder block by spraying an approximately 6 mm thick
layer using specially designed pumping and spraying equipment. The coating was then
dried in ambient conditions. Absorption coefficient of the coating, cinder block and
coated cinder block (Figure 3) were measured by using a reverberation chamber built
in a shipping container (6 m × 2.4 m × 2.4 m) using ISO 354:2003 "Acoustics. Measurement
of sound absorption in a reverberation room" as a guideline. Measurements were done
with 8 "Superlux ECM 999" microphones using ARTA software (
www.artalabs.hr/) for measurement and calculation of the results. Results illustrate clearly the advantage
of using porous background material underneath the coating.
CITATION LIST
Patent literature
1. An acoustic structure comprising a combination of a porous background structure and
an acoustic coating, characterized in that the acoustic coating is made of natural fibrous matter, does not contain any binders
and is applied by spraying on at least one surface of the porous non-felted background
structure, wherein the natural fibrous matter forms a fibre network on top of the
holes in the surface of the porous background structure, so that said surface can
be made plain.
2. The acoustic structure according to claim 1, characterized in that the natural fibrous matter is plant or plant-based fibre, such as cellulose, flax,
cotton or hemp fibre, or animal-based fibre, such as silk or wool-based fibre, or
a mixture of such fibres.
3. The acoustic structure according to any of the preceding claims, characterized in that the acoustic coating has a thickness between 1 to 30 mm, preferably between 3 to
10 mm.
4. The acoustic structure according to any of the preceding claims, characterized in further comprising 0-80% of mineral filler from its dry matter mass, preferably mineral
silicate, mineral sulphate or mineral carbonate, most preferably kaolin.
5. The acoustic structure according to any of the preceding claims, characterized in that the acoustic coating further comprises a fire retardant and an anti-rot agent, selected
from a group of boron-based substances, such as boric acid or borax or a mixture thereof,
hydroxides, such as aluminium or magnesium hydroxide or a mixture thereof, or absorbing
agents, such as talc or calcium carbonate or a mixture thereof, most preferably boric
acid or borax, particularly a mixture thereof, in an amount of 8-25% by weight of
the dry matter at the most.
6. The acoustic structure according to any of the preceding claims, characterized in that the acoustic coating comprises particles of different size scales, such as a combination
of cellulosic fibres with micro-fibrillated or nano-fibrillated cellulose.
7. The acoustic structure according to any of the preceding claims, characterized in that the porous background structure has density of 300 to 2200 kg/m3 and thickness of at least 2 mm, preferably at least 5 mm.
8. The acoustic structure according to any of the preceding claims, characterized in that the porous background structure preferably has a pore size of 1 to 16 mm.
9. The acoustic structure according to any of the preceding claims, characterized in that the porous background structure is for example a cinder block, or a perforated or
micro-perforated structure consisting of for example wood or metal.
1. Akustische Struktur, umfassend eine Kombination aus einer porösen Untergrundstruktur
und einem akustischen Belag, dadurch gekennzeichnet, dass der akustische Belag aus natürlichem Faserstoff hergestellt ist, der keine Bindemittel
enthält und durch Aufsprühen auf mindestens eine Oberfläche der porösen nicht gefilzten
Untergrundstruktur aufgetragen wird, wobei der natürliche Faserstoff ein Fasernetz
auf Löchern in der Oberfläche der porösen Untergrundstruktur bildet, sodass die Oberfläche
geebnet werden kann.
2. Akustische Struktur nach Anspruch 1, dadurch gekennzeichnet, dass der natürliche Faserstoff pflanzliche oder auf Pflanzen basierende Faser, wie Zellulose-,
Flachs-, Baumwoll- oder Hanffaser, oder Faser auf tierischer Basis, wie Faser auf
Seide- oder Wollbasis, oder ein Gemisch solcher Fasern ist.
3. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass der akustische Belag eine Dicke von 1 bis 30 mm, vorzugsweise von 3 bis 10 mm aufweist.
4. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass sie weiter 0-80% Mineralfüllstoff ihrer Trockenmasse umfasst, vorzugsweise Mineralsilicat,
Mineralsulphat oder Mineralcarbonat, am bevorzugtesten Kaolin.
5. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass der akustische Belag weiter ein Flammschutzmittel und ein Antifäulnismittel umfasst,
ausgewählt aus einer Gruppe von Substanzen auf Borbasis, wie Borsäure oder Borax oder
ein Gemisch davon, Hydroxiden, wie Aluminium- oder Magnesiumhydroxid oder ein Gemisch
davon, oder Absorptionsmitteln, wie Talk oder Kalziumcarbonat oder ein Gemisch davon,
am bevorzugtesten Borsäure oder Borax, insbesondere ein Gemisch davon, in einer Menge
von höchstens 8-25 Gewichtsprozent der Trockensubstanz.
6. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass der akustische Belag Partikel unterschiedlicher Größenskalen umfasst, wie eine Kombination
aus Cellulosefasern mit mikrofibrillierter oder nanofibrillierter Cellulose.
7. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die poröse Untergrundstruktur eine Dichte von 300 bis 2200 kg/m3 und eine Dicke von mindestens 2 mm, vorzugsweise mindestens 5 mm aufweist.
8. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die poröse Untergrundstruktur vorzugsweise eine Porengröße von 1 bis 16 mm aufweist.
9. Akustische Struktur nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die poröse Untergrundstruktur zum Beispiel ein Schlackenbetonblock oder eine perforierte
oder mikroperforierte Struktur ist, die zum Beispiel aus Holz oder Metall besteht.
1. Structure acoustique comprenant une combinaison d'une structure de fond poreuse et
d'un revêtement acoustique, caractérisée en ce que le revêtement acoustique est fabriqué en matière fibreuse naturelle, ne contient
pas de liant et est appliqué par pulvérisation sur au moins une surface de la structure
de fond poreuse non feutrée, dans laquelle la matière fibreuse naturelle forme un
réseau de fibres au-dessus des trous de la surface de la structure de fond poreuse,
de sorte que ladite surface peut être rendue lisse.
2. Structure acoustique selon la revendication 1, caractérisée en ce que la matière fibreuse naturelle est une fibre végétale ou d'origine végétale, telle
que la fibre de cellulose, de lin, de coton ou de chanvre, ou une fibre d'origine
animale, telle qu'une fibre à base de soie ou de laine, ou un mélange de telles fibres.
3. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce que le revêtement acoustique présente une épaisseur comprise entre 1 et 30 mm, de préférence
entre 3 et 10 mm.
4. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce qu'elle comprend en outre de 0 à 80 % de charge minérale à partir de sa masse de matière
sèche, de préférence du silicate minéral, du sulfate minéral ou du carbonate minéral,
le plus préférentiellement du kaolin.
5. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce que le revêtement acoustique comprend en outre un agent ignifuge et un agent anti-pourriture,
choisi parmi un groupe de substances à base de bore, telles que l'acide borique ou
le borax ou un mélange de ceux-ci, des hydroxydes, tels que l'hydroxyde d'aluminium
ou de magnésium ou un mélange de ceux-ci, ou des agents absorbants, tels que le talc
ou le carbonate de calcium ou un mélange de ceux-ci, le plus préférentiellement l'acide
borique ou le borax, en particulier un mélange de ceux-ci, en une quantité de 8 à
25 % en poids de la matière sèche au maximum.
6. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce que le revêtement acoustique comprend des particules de différentes échelles de taille,
comme une combinaison de fibres cellulosiques avec de la cellulose micro-fibrillée
ou nano-fibrillée.
7. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce que la structure de fond poreuse présente une densité de 300 à 2200 kg/m3 et une épaisseur d'au moins 2 mm, de préférence d'au moins 5 mm.
8. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce que la structure de fond poreuse présente de préférence une taille de pore de 1 à 16
mm.
9. Structure acoustique selon l'une quelconque des revendications précédentes, caractérisée en ce que la structure de fond poreuse est par exemple un parpaing, ou une structure perforée
ou micro-perforée constituée par exemple de bois ou de métal.