Studs of lined paper layers

Abstract

The present invention relates to a stud, which stud (1) comprises walls (2, 3) about a hollow core (6), said walls (2, 3) being made up of a plurality of joined layers of paper (4) surrounding said hollow core (6), said walls (2, 3) having a homogeneous thickness (T) in the range of 3-8 mm and comprising pairs of parallel walls (2, 3), with a first pair of shorter walls (2) having a width (B) substantially less than the corresponding cross-sectional length (L) of a second pair of parallel longer walls (3), wherein said walls (2, 3) comprise 7-15 layers of a paper layer (4) bonded with glue (5) wherein a plurality of said layers (40) have a grammage above 200 grams / m2, preferably 250 - 500 grams / m2 and wherein said plurality of said layers (40) comprise at least 80% recycled fibres.

Description

[0001] STUDS OF LINED PAPER LAYERS

[0002] TECHNICAL FIELD

[0003] The present invention relates to a novel stud of lined paper layers and a method of producing studs of lined paper layers.

[0004] TECHNICAL BACKGROUND

[0005] The construction industry is affected as well as other areas of the environmental requirements that consumers demand in different stages. In addition, financial requirements are always imposed on the end products, which means there is a need for reduced costs. These requirements that are desired to be met must not be at the expense of something else, such as safety, strength, workplace environment or the like.

[0006] From, US 610308, it is known that studs can be made of materials other than conventional wood and steel, in this case of composite. From SE 7702029-5 it IS known to make a stud by combining wood and plastic materials. Composite / plastic is a significantly worse alternative from an environmental point of view than wood and it may not compete from a price point of view. In case of fire, such a stud will contain much more energy that will lead to heavy heat generation and harmful flue gases from the plastic, not just carbon dioxide.

[0007] Construction elements made from cellulose fibres, e.g. paper, would bring about many benefits in relation to the above disadvantages related to studs in alternate materials. Many solutions are known, but none that may fulfil required needs for a stud in as successful manner. One specific problem when using paper has been to achieve sufficient reliability regarding strength to enable attachment by means of screws.

[0008] From DE 29610779 there is known a modular system using building elements that are built by layers of fiber material, e.g. paper, wherein the focus is to use the paper building elements as a concrete shed to enable in situ building with concrete, i.e. providing a significantly less heavy structural element to be shipped than in conventional concrete building. From WO 2015012692 and US 3159235 there are known foldable construction elements made up of corrugated board walls, which is rather complex and therefore relatively expensive. Further, from US 3238690 and GB 1391035D5 there are corrugated board elements in the form of supporting beams, i.e. large structural elements that are to carry heavy loads. A recent innovation is known from WO2017202836 wherein a specific combination of glued, spiral wound layers of paper provides studs that have reliable strength for attachment thereto by means of screws and which provide advantages regarding cost sustainability and ergonomic in relation to prior art studs. However, it has been found that there exist difficulties in obtaining sufficient straightness, i.e. many studs produced according to the novel concept get lengthwise twisted after being produced, in an undesirable manner.

[0009] BRIEF DESCRIPTION OF THE INVENTION

[0010] It is an object of the present invention to greatly reduce environmental impact, price and fire risk compared with current studs, which is achieved by a stud according to claim 1.

[0011] Thanks to the invention, a structural element is obtained primarily for use in houses and other buildings where demands from consumers regarding the environment, fire risk and price can be more easily met, while at the same time building standards can be met. A stud in paper has significant environmental benefits, both in relation to composite, wood and steel. None of the previously known materials can achieve the economic benefits that a stud in paper can.

[0012] Thanks to the invention, a stud is obtained which provides an easier-to-use product with high environmental and cost advantages, which meets durability requirements, etc. in comparison with known materials, i.e. mainly steel and wood. The invention relates to a structural element which is primarily intended for use in houses and other buildings. Thanks to the invention, the working environment for construction workers will also be improved since a stud according to the invention of paper is substantially less heavy than known studs and hence better from a handling point of view, as well as possible to cut off without chip formation and with substantially noiseless methods.

[0013] The invention also relates to a beneficial method of making a stud having a bent joint according to claim 11.

[0014] BRIEF FIGURE DESCRIPTION

[0015] In the following, the invention will be described in more detail, with reference to the two accompanying figures wherein;

[0016] Fig. 1 shows a perspective view of an upper part of a stud according to the invention, Fig. 2 shows a schematic enlargement of a corner of this stud,

[0017] Fig. 3 shows a bunch of studs in a preferable mode in connection with production thereof.

[0018] Fig. 4 shows a partly cut through stud to create a strong bent joint, Fig. 5 shows a bent joint of 90° according to a novel concept,

[0019] DETAILED DESCRIPTION

[0020] In Figure 1, a perspective view of a stud 1 is shown of one embodiment of the invention, presenting a hollow rectangular cross-section with a short wall 2 and a long wall 3. The stud 1 is made up of a plurality of joined layers of paper 4.

[0021] The stud is preferably designed so that its short wall 2 has a width B which is substantially less than the corresponding cross-sectional length L of the longer wall 3, preferably the ratio is such that 2B> L> 1.3B. The thickness of the wall is chosen to be about 5-12 mm, preferably 5-10 mm. According to a preferred embodiment, the walls 2,3 comprise 7-15 layers of a paper layers 4 (see Fig. 2) wherein each layer 40 of a more part of the plurality of paper layers 4 has a grammage above 200 grams / m2, more preferred the more part of said layers 40 comprise 7-12 layers with a grammage of 250- 500 grams / m2. Preferably, paper is used mainly made of short, recycled paper fibers, which is an advantageous choice because the short-fiber composition causes the paper of said layers 40 to have a tight structure that provides good strength, and form stability.

[0022] The paper layers 4 are joined with glue 5. The adhesive used is preferably polyvinyl acetate, which is an advantageous choice because it is water-soluble and cost-effective.

[0023] The invention relates to a stud 1 as a structural element primarily for use in houses and other buildings, which means that requirements from consumers regarding the environment and price can be met without impairing other requirements.

[0024] Today, for the most part, studs are made of steel for building inner, non- supporting walls, alternatively wood, which, from several view-points, present disadvantages. With the inventive stud 1, there is provided a more easy-to-use product with great environmental and cost advantages that, in principle, meet all the requirements in terms of durability, etc., as competing materials have.

[0025] The stud 1 has hollow core 6, see Fig. 1. One embodiment of the stud 1 preferably has outer dimensions B = 45 and L = 70 mm. The construction of it has been made by winding several layers of paper layers 4 glued with, e.g. polyvinyl acetate, adhesive 5 around a rectangular core (not shown) so that the total thickness preferably is 5-10 mm. The main part of the fibers in the majority of the paper layers 40 are suitably made from pulp of recycled short fibers.

[0026] Thanks to the invention, a stud is obtained with many advantages, as mentioned above. Further, tests have shown that with a construction element according to the invention a stud can be created of unexpectedly good strength and form stability. Below are test results comparing the novel design with the previous design

[0027] As can be noted from the above table significant improvements may be achieved with the novel design, i.e. 500% improvement of form stability.

[0028] When used to build a wall (not shown), the stud 1 may be attached in principle in a same manner as a stud made of wood, by desired attachment means (not shown) e.g. screw or nail and / or glue. Then, building boards or other construction elements (not shown) can be attached to chosen side / s of the studs 1. The rigidity and strength when combined with building boards, such as a plasterboard, is fully sufficient to meet all the building requirements that authorities require.

[0029] In case of fire, the paper stud 1 will not lead heat in the same way that metal does. The paper stud 1 also contains no more than a fraction of the energy contained in a wood stud, whereby no significant amount of heat will develop by the studs in a fire. There is also only an insignificant amount of harmful flue gases in the event of fire.

[0030] A stud 1 in hollow-core paper also has the advantage of being able to process it with simple means, for example by means of a regular knife, e.g. to make holes in it for water and electricity pipes and / or to cut off it into desired lengths. In addition, it is very light weight which is a great advantage from the working environment point of view.

[0031] In Fig. 3 it is shown that the studs 1 in connection with production thereof after termination of gluing, preferably are grouped together in bunches of at least four and kept tightly in contact with each other in the bunch by means of resilient wrapping 7. Immediately after production the studs 1 have a relatively high moist content (normally within the range of 10-20% of the weight) due to the added glue, which is in liquid form. Hence, drying of the studs 1 is needed before delivery / use. During the drying process it is beneficial to have a plurality of studs grouped together in a bunch that by some tensioning arrangement keeps the studs tightly together, which will assist in allowing the studs 1 to become dry under conditions providing a relatively little twist, i.e. within acceptable limits of twist. The drying process wherein the plurality of studs are grouped together in a bunch is preferably performed until the moist weight content is at or below 6%, preferably at or below 5%.

[0032] Preferably a bunch includes at least four studs, in two rows and two columns, such that each stud may be in contact with at least one neighbouring stud both with a side wall 2 and a top or bottom wall 3. Two rows and three columns may be more preferred under some conditions and under other conditions three rows and three columns may be more preferred, etc. The resilient wrapping 7 preferably comprises a plurality of wrapping members 70 dispersed, e.g. at every 0,5-1 m, along the length of the bunch. Each wrapping member 70 should preferably be less than 100 mm wide, preferably less than 60 mm wide, to not negatively affect the drying process. Multiple layers of plastic film (preferably very thin) may be a suitable wrapping member 70 since it is cost-efficient and may contribute with a controllable tension (the more layers the more tension may be applied).

[0033] The exact production of a stud 1 is not limited to what has been described above, but may be varied within the scope of the appended claims.

[0034] In Fig. 4 it is shown that the stud 1 may be prepared for being bent into a bent joint 8, e.g. 90° as shown in Fig. 5.

[0035] The stud in Fig. 4 is provided with a plurality of cuts 21, 31, 32 (thicker lines) that cut through the walls 2, 3 of the stud 1. On each side wall 2 there is a first angled side cut 21 that extends at an angle a in relation to the plane of a bottom wall 35 up to the top wall 36. From the end point 2 IB at the top there extend longitudinal through cuts 31 along the corners of transition between the top wall 36 and the side walls 2. The ends 31A of the longitudinal through cuts 31 are bridged by a transversal through cut 32, that extends perpendicularly across the top wall. The distance of the longitudinal cuts 31 corresponds to an angle y that is formed between the line of the side cuts 21 and side piece folding lines 22, that along each side wall 2 run along an angle P and having its lower end point coinciding with the start point 21A of the first cutting lines 21. The angles a + P + y = 180°. In the shown example a = P = 45° and y = 90°, i.e. providing a a bent joint 8 of 90°, i.e. a corner as shown in Fig 5.

[0036] Further it is shown that there is a further folding line 23 on each side wall 2, which folding lines will facilitate folding of each cut loose triangular side piece into the hollow space 6 of the stud 1. Finally, there is a through cut 32 that runs from the end 31A of the corner cutting lines 31 transversally through the top side wall 3, which will form a loose rectangular tongue part 30.

[0037] Accordingly, there will be produced a rectangular piece 30 that is cut loose from the top side wall 36 and which may be arranged with a folding line 33 at its bottom.

[0038] In Fig. 5 it is shown that the rectangular tongue 30 has been bent down into the hollow inner 6 of the stud 1, by means of pivoting along its folding line 33. Further it is shown that the triangular side pieces 20 have been folded along the middle folding lines 23 and pressed into the hollow inner 6 of the stud 1. Then by pivoting the stud 1 along a bottom folding line 24 the rectangular tongue 30 will be pushed into the hollow inner 6 of the stud 1. The pivoting enables an upper part 2B, 3B of the stud 1 to form an angle a + P in relation to a lower part 2A, 3A, such that a bend of corresponding to the two angles a+P will be achieved. Hence the pivoting is terminated, the a bent joint 8 produced, when the area of the upper folding line 33 of the tongue 30 meets the transversal cut 32 and also the area of the side folding lines 22 of the triangular parts 20 meet the angled side cuts 21. In the shown embodiment a and P are 45° such that the stud 1 when folding along the folding line 24 will form a bend of 90°. As is evident also the triangular folded side pieces 20 will be contained within the hollow inner 6 of the stud 1.

[0039] Thanks to the design the tongue 30 will add strength to the a bent joint 8 and as will also the triangular folded pieces 20 within the interior of the stud, by being in contact with the inner walls that form the limits of the hollow inner 6. Accordingly, a stabilized, strengthened a bent joint 8 will be formed.

[0040] It is evident for the skilled person that by amending the angles a and P the angle y of the triangular side pieces 20 will also change, providing the possibility to create a bent joints 8 of different angles, e.g. a bent joint of 135°, wherein a= P = 67,5° and y = 45° or of 45°, wherein a= P = 22,5° and y = 135°. It is understood that improved stability / strength is also achieved if merely the tongue piece 30 is used, i.e. cutting through also at folding lines 22, such that the side pieces 20 are taken away. Further it is understood that the tongue piece 30 must not be parallel epipetric to provide strength, since normally it will be the cut edges adjacent the folding line 33 that provide more support than the distant part of the cut edges. Moreover, this leads to understand that not the whole part of the cut tongue piece 30 must be used, i.e. it is foreseen that an outer part of the cut tongue piece 30 may be cut off prior to making the joint / bend. Further it is understood that the bent joint 8 according to the invention may also be used for other studs than the embodiment claimed in claim 1, i.e. it may be used for any kind of stud 1 made of a plurality of joined layers of paper 4 surrounding a hollow core 6, which may be the subject for a separate divisional application.

Claims

CLAIMS1. A stud for buildings, which stud (1) comprises walls (2, 3) about a hollow core (6), said walls (2, 3) being made up of a plurality of joined layers of paper (4) surrounding said hollow core (6), said walls (2, 3) having a homogeneous thickness (T) in the range of 3 -8 mm and comprising pairs of parallel walls (2, 3), with a first pair of shorter walls (2) having a width (B) substantially less than the corresponding cross-sectional length (L) of a second pair of parallel longer walls (3), characterized in that said walls (2, 3) comprise 7-15 layers of a paper layer (4) bonded with glue (5) wherein a plurality of said layers (40) have a grammage above 200 grams / m2, preferably 250 - 500 grams / m2 and wherein said plurality of said layers (40) comprise recycled fibres.

2. A stud according to claim 1, characterized in that said plurality of said layers (40) comprise at least 60%, more preferred at least 80% recycled fibres least, even more preferred at least 90% recycled fibres, even more preferred at least 95% recycled fibres, most preferred 100% recycled fibres.

3. A stud according to claim 1, characterized in that said walls (2, 3) have a homogeneous thickness (T) above 4 mm, preferably in the range of 5-12 mm, more preferred 5-10 mm.

4. A stud according to claim 1, characterized in that said walls (2, 3) comprise at least one outer layer of a paper layer (41) with a grammage, below 200 grams / m2, of 170-180 grams / m2.

5. A stud according to claim 4, characterized in that said outer paper layer (41) has a hydrophobicity that is at least 50% better than the hydrophobicity of said inner layers (40), preferably at least 100% better.

6. A stud according to any one of claims 1 to 4, characterized in that said paper layer (4) is joined by a polyvinyl acetate adhesive (5).

7. A stud as claimed in any of claims 1 to 6, characterised in that it includes a bent joint (8) forming a first stud part (2A, 3 A) joined at an angle (a+P) by means of an integral pivot line (24) formed in an outer wall (35) of said stud (1) having a bent joint (8).

8. A stud according to claim 7, characterized in that said bent joint (8) includes at least one cut loose piece (20, 30) positioned within said hollow space (6).

9. A stud according to claim 8, characterized in that said at least one cut loose piece (20, 30) positioned within said hollow space (6) includes at least a tongue piece (30), which is cut loose from an inner wall (36) opposite to the outer wall (35).

10. Method in connection with production of a stud according to any preceding claim, characterized by after termination of gluing tightly grouping together at least four studs (1), wherein each stud (1) each stud is in contact with at least one neighbouring stud both with a side wall (2) and a top or bottom wall (3) in a bunch by means of resilient wrapping (7) and subsequently drying of the studs (1) to a humidity level below 10%, preferably at or below 6%, before releasing said resilient wrapping (7), wherein preferably said resilient wrapping (7) comprises a plurality of wrapping members (70) having a width of less than 100 mm positioned at intervals, suitably at every 0,5 -1,5 m, along the length of said bunch, wherein more preferred each wrapping members (70) includes multiple layers of plastic film.

11. A method for forming a bent joint (8) of a stud (1) made of a plurality of lined paper layers (4) with a hollow interior (6), including the following steps: a), making a plurality of through cuts (21, 31, 32) in two side walls (2) and an inner wall (36) of the stud (1), forming at least one cut loose piece (20, 30) attached by means of a pivot line (22,33), wherein said cuts (21) in the side walls (2) extend parallel at a first sharp angle (a) in relation to a plane of extension of the outer wall (36) along the whole side wall (2) from an outer end point (21 A) to an inner end point (2 IB) and said cuts (31, 32) in said inner wall (36) include two longitudinal parallel cuts (31) along the longitudinal corner areas of the inner wall (36) having as one end point the inner end point (21B) of said side cuts (21) and a second end point (3 IB) wherein a transversal cut (32) in said inner wall (36) bridges the two end points (3 IB) of said longitudinal cuts (31) such that a cut loose tongue piece (30) is formed attached by means of a pivot line (23), b) inserting at least said one cut loose piece (20, 30) into a hollow interior (6) of said stud (1) and pivoting said stud (1) around a pivot line (24) extending transversally in an outer wall (35) of said stud (1) and simultaneously allowing said at least one cut loose piece (20, 30) to be maintained in the hollow interior (6) of said stud (1) such that s stud with a bent joint (7) is produced.

12. A method according to claim 11, wherein at least two of said cut loose pieces are introduced into said hollow interior (6),13. A method according to claim 11 or 12, wherein said longitudinal parallel cuts (31) along the longitudinal comer areas of the top wall (35) extend a distance (L) such that lines (22) along each side wall (2) between said outer end point (2 IB) and said tongue end point (31 A) form a second sharp angle (P) in relation to the extension of the plane of the outer wall (36) that is equal to the first sharp angle (a).

Images