GB2461541A

GB2461541A - Insulating batt with multidirectional tearability

Info

Publication number: GB2461541A
Application number: GB0812088A
Authority: GB
Inventors: Stephen Andrew Midgley; Carl Antony Rushden; Simon John Irwin
Original assignee: John Cotton Group Ltd
Current assignee: John Cotton Group Ltd
Priority date: 2008-07-02
Filing date: 2008-07-02
Publication date: 2010-01-06
Anticipated expiration: 2028-07-02
Also published as: GB2461541B; GB0812088D0

Abstract

There is disclosed a method of manufacturing a non-woven insulating batt, comprising forming the batt by air laying predetermined staple fibres such that the staple fibres are randomly oriented at least within a plane of the batt, optionally with the addition of at feast one binder in a predetermined amount. The batt thus formed can be ripped or torn by hand in more than one direction parallel to the planes of the layers of the web.

Description

INSULATING BATT WITH MULTIDIRECTIONAL TEARABILITY

The present invention relates to an insulating batt and a method of manufacturing an insulating batt, the batt being particularly well-suited for thermal insulation of buildings, especially roof spaces, although other applications are not excluded.

BACKGROUND

It is well-known to provide fibre-based insulating products for thermal insulation of buildings, especially in roof spaces thereof. Such products typically comprise man-made mineral fibres (MMMF) which are spun fibres, commonly known as rock wool, slag wool or glass wool. Such fibres can be supplied in batt form, or may be air deposited (blow filled) in situ or simply poured into the roof or loft space (loose fill). Other types of loose fill material include polystyrene beads, vermiculite, cellulose and blown polyurethane foam.

It is known to provide fibre-based loft insulation in the form of batts which are provided in roll form and then simply unrolled, for example between and over joists, in a roof space so as to provide additional thermal insulation for a house. Such materials can also be used in timber frame walls and between rafters, as well as in many other situations, such as around water tanks and pipes.

This type of insulation is easy to install, even by homeowners themselves without requiring specialist help, and can be relatively cheap to manufacture. By installing insulation, a significant reduction in heating energy to keep a building warm can be realised, which is not only economically advantageous, but also environmentally important.

Alternative insulation batts can be made from natural or recycled materials such as wool, hemp, cotton, flax, polyester, recycled textiles or cellulose. These fibrous materials can be processed through fibre opening and process equipment, for example by way of fibre openers and carding machines.

However, carding becomes less practical as a manufacturing technique when very fine fibres are used, although it is desirable to use fine fibres since these generally have better thermal insulating properties.

Conventionally, fibres that have been carded are cross-layed or cross-lapped to obtain a batt of desired thickness and weight. In cross-laying, the fibres tend to be oriented across the laying machine direction, and the resulting batt can be easily torn in one direction (parallel to the fibres, i.e. across the machine direction) but not the other (across the fibres, i.e. with the machine direction). It is possible to improve tearability by using short fibres, for example less than 38mm in length. Poor carding of the fibre, resulting in balling or nepping, can improve "With Machine Direction" (WMD) tearing, but the resulting product loses a significant degree of its insulating properties. Drafting of the batt can also improve WMD tear, but drafting is not a realistic solution when dealing with a high loft, high weight insulation.

It is known, for example from GB1151720, to provide an apparatus and method for forming non-woven webs by way of an air laying process. Fibres are blown in an air stream onto a surface of a rotating screen drum to form a web, which web is then transferred to a conveyor belt and transported away for additional processing steps, such as folding into batts. The web formed in this method tends to have the fibres mainly oriented in the plane and longitudinal direction of the web. Alternatively, two counter-rotating screen drums can be used to form a web in having top and bottom surfaces with fibres oriented in the direction of the web, and a fibre orientation between the top and bottom surfaces that is perpendicular to the plane of the web.

A more recent example of an air laying process is described in AT502643, which describes the formation of a web by blowing fibres along a channel bounded by walls directly onto a suction belt rather than onto a surface of a drum. This is stated to provide improved directionality of the fibres in the resulting non-woven web.

A disadvantage that arises from rotating screen drum air laying of fibres when forming a web is that fibre "chimneys" can form between the top and bottom surfaces of the batt, thus assisting heat transfer through the batt.

Another disadvantage is that batts formed from non-woven fibres having a high directionality is that these batts are easily tearable in one direction across the batt, but not in an orthogonal direction (this is a similar disadvantage to that displayed by cross-layed carded fibre batts). This means that it can be difficult to tear out parts of an insulating batt so as to help it conform to an area in which it is being deployed, for example in a roof space around and between joists and pipework.

Yet another disadvantage of batts formed from non-woven fibres with high directionality is that such batts generally do not have good loft recovery. In other words, if they are compressed, especially for a prolonged period of time (as is often the case when such batts are packaged for transport and sale), they do not recover their original dimensions quickly and easily, if at all. This is particularly problematic when fine staple fibres are used. Compressed batts can be less effective thermal insulators, since less air is held stationary in such batts to act as an insulating layer. Since finer fibres generally provide the best insulation, poor loft recovery can be a major problem. Indeed, cross-layed fibre batts with staple fibres having a linear density of less than around 1 to 5 dtex do not have good loft recovery.

BRIEF SUMMARY OF THE DISCLOSURE

According to a first aspect of the present invention, there is provided a method of manufacturing a non-woven insulating batt, comprising forming the batt by air laying predetermined staple fibres such that the staple fibres are randomly oriented at least within a plane of the batt, optionally with the addition of at least one binder in a predetermined amount.

According to a second aspect of the present invention, there is provided a non-woven insulating batt formed by air-laying predetermined staple fibres in a substantially random orientation within at least a plane of the insulating batt such that the insulating batt can be ripped or torn by hand in more than one direction parallel to the planes of the layers of the web.

Preferably, the fibres are configured such that the batt can be torn (by hand) in at least two generally orthogonal directions in its plane, the tearing force required in each direction preferably being substantially the same.

In some embodiments, the fibres are configured to allow the batt to be torn (by hand) in any direction in the plane of the batt, the tearing force in each direction preferably being substantially the same.

By providing multidirectional tearability, in contrast to insulating batts made by processes in which fibres are generally aligned in one predominant direction, insulating batts of embodiments of the present invention are easy to fit around joists and pipework and the like.

The fibres are preferably substantially randomly oriented in three dimensions, i.e. in all directions, throughout the batt.

Another important advantage obtained by a substantially random fibre orientation is that batts of embodiments of the present invention tend to recover their loft more quickly after compression than standard cross laid fibre batts.

Where the staple fibres are newly-manufactured or "virgin" man-made fibres, such as polyester, polypropylene, acrylic, nylon or similar fibres, it is possible to specify a preferred staple fibre length or a well-defined range of fibre lengths. This is because the virgin fibres can be spun and chopped into the preferred lengths during initial manufacture. It is also possible to specify a preferred linear density or range of linear densities of such virgin fibres. In currently preferred embodiments where virgin man-made fibres are used as the staple fibre (or as a constituent of a staple fibre blend), an average fibre length of 30 to 80mm, preferably 40 to 60mm, most preferably 50 or 51mm, gives good tearability and loft recovery. A linear density of no more than 7 dtex is also preferred, particular for polyester fibres.

Alternatively, natural materials such as flax, wool, cotton, hemp and the like may be used as the staple fibre, or as a component in a blend of staple fibres including the virgin man-made fibres described above. Man-made mineral fibres may also be used, by themselves or as part of a blend, as may recycled polymer fibres or recycled textile fibres. It is generally not easy or even possible to specify a tightly-defined range of fibre lengths and densities when not using virgin fibres, but by ensuring a substantially random fibre orientation within the batt, and also trying to use fibres that tend not to be too long, can assist multidirectional tearability and loft recovery. Including virgin fibres having well-defined length and linear density characteristics as previously described in a blend also containing natural or recycled fibres can provide reasonable control of multidirectional tearability and improved loft recovery.

Advantageously, the staple fibre is bonded by blending in binder fibres, for example polyester binder fibres (e.g. from 4 to 5 dtex, preferably 4.4 dtex, and 40 to 60mm, preferably 51mm). A high percentage of binder fibre will be detrimental to tearability.

The present applicant has found that good tearability is found in the range from 3 to 18% binder fibre, preferably 7 to 15%.

If no binder fibre is used, tearability in all directions is good, but the resulting batt tends to lack handling integrity and will tend to come apart easily.

The bond strength generally depends on the processing temperature as well as the amount of binder fibre. For example, using high percentage levels of binder fibre (e.g. 18%) and a relatively low processing temperature (e.g. 110°C) results in a product having a similar tear strength as one using a lower percentage level of binder fibre (e.g. 3%) and a relatively high processing temperature (e.g. <130°).

With regard to the staple fibres (as opposed to the binding fibres), a long staple length (e.g. >80mm) will reduce tearability. In addition, random staple lengths (as in natural fibres) will also reduce tearability. It is therefore preferred to use a virgin man-made staple fibre chopped into relatively consistent lengths, preferably between 30mm and 80mm. The applicant has found experimentally that a staple fibre length of around 51mm works well.

Fine fibres (e.g. <7dtex) will have more bond points. Moreover, fine fibres generally have better insulating properties.

Suitable materials for the staple fibre include (but are not limited to) polyester, cotton, wool, hemp, flax, recycled textiles, polymers, recycled polymers (for example sourced from polymer-based packaging and bottles) and glass.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS: 1. A method of manufacturing a non-woven insulating batt, comprising forming the batt by air laying predetermined staple fibres such that the staple fibres are randomly oriented at least within a plane of the batt, optionally with the addition of at least one binder in a predetermined amount.
2. A method according to claim 1, wherein binder fibres are included in addition to the predetermined staple fibres.
3. A method according to claim 2, wherein the binder fibres are polyester or polypropylene fibres.
4. A method according to claim 2 or 3, wherein the binder fibres have a linear density of 4 to 5 dtex, preferably 4.4 dtex.
5. A method according to claim 2, 3 or 4, wherein the binder fibres have an average length of 40 to 60mm, preferably 51mm.
6. A method according to any one of claims 2 to 5, wherein the binder fibres comprise 3 to 18%, preferably 7 to 15%, of the total fibre weight.
7. A method according to any preceding claim, wherein the staple fibres are man-made virgin polymer fibres.
8. A method according to claim 7, wherein the staple fibres are made of at least one material selected from the group comprising polyester, polypropylene, acrylic and nylon.
9. A method according to claim 7 or 8, wherein the staple fibres have an average length from 30 to 80mm, preferably 40 to 60mm, most preferably 50 or 51mm.
10. A method according to any one of claims 7 to 9, wherein the staple fibres are all of substantially the same length as each other.
11. A method according to any one of claims 7 to 10, wherein the staple fibres have an average linear density of no more than 7 dtex.
12. A method according to any one of claims 1 to 6, wherein the staple fibres are made of at least one material selected from the group comprising: cotton, wool, hemp, flax, recycled textiles, recycled polymers, mineral fibres and glass.
13. A method according to any preceding claim, wherein the staple fibres comprise a blend of man-made virgin polymer fibres and natural or recycled fibres.
14. A method according to any preceding claim, wherein the batt is subjected to heating after being formed, preferably to a temperature of at least 110°C.
15. A method according to any preceding claim, wherein the fibres are oriented substantially randomly in all directions throughout the batt.
16. A non-woven insulating batt formed by air-laying predetermined staple fibres in a substantially random orientation within at least a plane of the insulating batt such that the insulating batt can be ripped or torn by hand in more than one direction parallel to the planes of the layers of the web.
17. A batt as claimed in claim 16, wherein the batt is tearable by hand in at least two generally orthogonal directions in its plane, the tearing force required in each direction preferably being substantially the same.
18. A batt as claimed in claim 16 or 17, wherein the batt is tearable by hand in any direction in the plane of the batt, the tearing force in each direction preferably being substantially the same.
19. A batt as claimed in any one of claims 16 to 18, wherein binder fibres are included in addition to the predetermined staple fibres.
20. A batt as claimed in claim 19, wherein the binder fibres are polyester or polypropylene fibres.
21. A batt as claimed in claim 19 or 20, wherein the binder fibres have a linear density of 4 to 5 dtex, preferably 4.4 dtex.
22. A batt as claimed in any one of claims 19 to 21, wherein the binder fibres have an average length of 40 to 60mm, preferably 50 or 51mm.
23. A batt as claimed in any one of claims 19 to 22, wherein the binder fibres comprise 3 to 18%, preferably 7 to 15%, of the total fibre weight.
24. A batt as claimed in any one of claims 16 to 23, wherein the staple fibres are man-made virgin polymer fibres.
25. A batt as claimed in claim 24, wherein the staple fibres are made of at least one material selected from the group comprising polyester, polypropylene and acrylic.
26. A batt as claimed in claim 24 or 25, wherein the staple fibres have an average length from 30 to 80mm, preferably 40 to 60mm, most preferably 50 or 51mm.
27. A batt as claimed in any one of claims 24 to 26, wherein the staple fibres are all of substantially the same length as each other.
28. A batt as claimed in any one of claims 24 to 27, wherein the staple fibres have an average linear density of no more than 7 dtex.
29. A batt as claimed in any one of claims 16 to 23, wherein the staple fibres are made of at least one material selected from the group comprising: cotton, wool, hemp, flax, recycled textiles, recycled polymers, mineral fibres and glass.
30. A batt as claimed in any one of claims 16 to 29, wherein the staple fibres comprise a blend of man-made virgin polymer fibres and natural or recycled fibres.
31. A batt as claimed in any one of claims 16 to 30, wherein the fibres are oriented substantially randomly in all directions throughout the batt.
32. A method of manufacturing a non-woven insulating batt substantially as hereinbefore described.
33. A non-woven insulating batt substantially as hereinbefore described.