HUP0300019A2 - Glass fibre mat and use thereof for built-up roofing - Google Patents

Abstract

The subject of the invention is a fiber-based veil, which can be used for the formation of bituminous membranes and which contains glass fibers, organic fibers and a binder. The essence of the invention is that the rate of contraction of organic fibers at 130 °C is less than or equal to 5%. The invention is also a bituminous membrane, which has a coating base and is coated or impregnated with a bituminous sticker, the base of which is 1-8. Veil according to claims. HE

Description

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FIBER-BASED VEIL 97.355-7649 KH

The invention relates to a fiber-based web that can be used to form bituminous membranes and that comprises glass fibers, organic fibers and a binder.

In the field of coverings or sealings, it is known to use bituminous membranes which are applied to the surface to be covered or sealed. These membranes generally consist of a sheet base which is coated or impregnated with a bituminous matrix.

The sheet materials can be of various natures and are generally made of organic fibers or mineral fibers, preferably in non-woven form.

Of the materials that can be used, glass fleeces are of the greatest importance, as they ensure dimensional stability for the lifetime of the bituminous membrane.

The glass veils can be produced by any known technique, especially by a wet method, such as that described in the following publication: "The Manufacturing Technology of Continuous Glass Fibres, K. L. LOEWENSTEIN, Ed. ELSEVIER, 1983, pages 315-317.

This technique, which is part of the papermaking process, consists of preparing an aqueous suspension of chopped glass fibers, placing this suspension in a film on a filter mat that is subjected to suction to remove some of the water from the film applied, applying a binder composition to the wet film, then drying the web and crosslinking the binder in a drying chamber, then conditioning the web as desired. The final product appears in the form of a fairly fine sheet, 0.2 to 0.8 mm thick, which is usually rolled up in the form of a cylinder.

The binder is often an aqueous composition based on urea-formalin resin, which resin exhibits satisfactory behavior at temperatures

-2which occurs during the subsequent impregnation of the bitumen.

Glass veils have several shortcomings, including their relatively low resistance to tearing, which affects their potential applications and forces the user to take precautions when producing the membrane or placing it on the roof.

To overcome this shortcoming, complex bases exist that combine an organic fiber-based web with good tear resistance and a glass grid that gives the unit dimensional stability. These complex shapes, which are composed of two products, require complicated manufacturing.

The aim of the invention is to create a glass-like material with better resistance to tearing, without being more complicated to manufacture than conventional veils.

EP-A-0 763 505 describes a mat of glass fibres for the manufacture of bituminous roof shingles, the strength of which is improved by a urea-formalin binder modified with a vinyl self-shrinking additive. In this mat, a minor proportion of the fibres may be glass fibres, which may be selected from organic materials such as nylon, polyester, polypropylene, etc. This specification does not give precise guidance on organic fibres and does not contain any examples illustrating this possibility.

The invention is based on the recognition that many organic fibers are not suitable for producing a web, and even have a very negative effect on the properties of the web when used in bituminous pavements, but by very precise selection of synthetic materials this deficiency can be overcome.

Therefore, the object of the invention is to provide a web based on fibers suitable for producing bituminous membranes, which web comprises glass fibers and organic fibers bonded with a binder and which web is characterized in that the shrinkage of the fibers is less than or equal to 5% at 130° C.

It is noted that the term "glass fiber web" in the context of the invention refers to materials that are well known to those skilled in the art and that are glass fiber-based products. It refers to thin sheet-shaped standing materials that generally have an isotropic structure, i.e. the fibers do not have a preferred orientation. In practice, a web can be characterized by the isotropic ratio, i.e. the tensile strength of the web in the machine direction / the tensile strength of the web in the cross direction, which ratio is generally of the order of 1, or of the order of 1-1.5, sometimes 2. This orientation of the fibers is generally achieved from the time the glass fibers appear as chopped strands for the purpose of forming the web, for example in the wet process mentioned above.

The choice of organic fibers based on the above criteria gives the veil good quality, in particular a mechanical and thermal strength comparable to the previous use, which was done by impregnation with bitumen, while the other fibers give the veil insufficient thermal and mechanical strength.

The organic fibers used in the production of the web primarily have a higher melting point in order to avoid their degradation during each thermal stage of the web production, namely drying and crosslinking in the drying chamber, as well as during the use of the web, especially in contact with the bituminous binder. In general, the synthetic organic material is chosen so that its melting point is higher than 220 C.

According to the invention, the fibers are selected for their degree of thermal shrinkage. This degree corresponds to a change in size, a spatial shortening of the fiber after it has been exposed to a given temperature for a given time. For this purpose, the initial length Li of the fiber before heating, then the final length Lf, is measured and the degree of shrinkage is:

-4r = (Li - Lf) / Li

The critical shrinkage values were determined at a temperature of 130°C, in a steam atmosphere, for a period of 30 minutes.

According to the invention, the shrinkage is chosen to be less than or equal to 5%, preferably 4%, in particular 3%, for example 2-3%.

Preferably, fibers of this quality can be obtained from semi-crystalline polymer materials, especially those in which the fiberization allows a stretching that increases the degree of crystallinity. Other manufacturing conditions, such as the presence of nucleating agents or the temperature factor, can also result in underlying macromolecular structures, so that the starting amorphous polymer begins to transform into a crystalline structure and becomes semi-crystalline.

Fibers that meet the requirements of the invention can be found among polyester fibers, in particular alkylene polyterephthalate or ethylene polyterephthalate.

Preference is given to organic fibers that are suitable for the production of nonwovens by the wet process and that, with the use of oiling, allow the dispersion of the individual Substrates in water.

The dimensions of the organic fibers can vary, with an average diameter of the order of 7-25 mm for a titer of 0.5-2 dtex. The fibers are preferably cut to lengths of the order of one or a few tenths of a mm, preferably 6-30 mm.

The effect of organic fibers is noticeable when their proportion is at least 5% by weight, based on the total weight of the fibers. The proportion of organic fibers is preferably 5-30% by weight, especially 20-30% by weight and most preferably about 25% by weight, based on the total weight of the fibers.

The glass fibers used in the invention are glass fibers commonly used in the production of webs, preferably in the form of chopped strands, the length of which is in the order of tenths of a millimeter, namely 6-30 mm, preferably 1020 mm, for example 12-18 mm. It is understood that a certain portion of the fibers, for example 5-10%, can be chopped to a length that can be 100 mm. In addition

X

-5 A continuous fiber, especially glass fiber, can be introduced into the web as reinforcement in the longitudinal direction.

The binder used to form the web is preferably based on urea-formalin resin, which is suitably modified with vinyl and/or acrylic additives, as described in US 4,681,802 and EP - A - 0 763 505. The amount of binder is generally 15-30% by weight of dry matter relative to the web.

The veil is made in the usual weight for glass veils, which is 30-150 g/m , or especially 50-120 g/m .

Taking into account the density difference between glass and organic fibers, the amount of material present in the web of the invention per gram weight is slightly higher than in glass webs, which results in a relatively greater thickness and lower porosity. The porosity is, for example, 1500 l/m ² /s for a 50 g/m ² web.

The veil according to the invention is highly suitable for use as a seal and/or covering, so that the subject of the invention is a bituminous membrane having a coating base and this is coated or impregnated with a bituminous matrix, the base being the veil described above.

The bituminous matrix can be selected from known matrices, it can be natural bitumen, modified or unmodified, synthetic binder, such as a glossy binder, which gives the membrane a decorative color.

The invention is described below with reference to examples.

Example 1

An aqueous suspension is prepared from the fibers, in which the fibers contain:

- 75% by weight of chopped glass fiber, with a filament diameter of 10 millimicrons and a linear mass of 360 tex, and a cut length of 12 mm,

- 25% by weight of staple polyester fiber, which is distributed by KURARAY EP

-6133 and is used in papermaking and is water-dispersible. This fiber is characterized by a filament diameter of 12 millimicrons, a linear mass of 1.4 dtex and a cut length of 15 mm. It is an ethylene-polyterephthalate fiber, stretched to increase its crystallinity, and has a shrinkage rate of 2% at 130° C in a humid environment in 30 minutes and a shrinkage rate of 3% at 170° C in a dry atmosphere in 15 minutes.

The suspension of fibers, which surrounds the usual additives such as antifoams, dispersants, viscosity enhancers, is applied under normal conditions on a web-forming machine, which machine comprises a hydraformer on which a wet shell is formed by partial extrusion, and a binder application station which applies the binder by spraying, or by dipping, or by passing through a bath containing an aqueous solution based on a urea-formalin resin, plasticized with acetate and acrylic, which deposits on the web a binder amount of 19% by weight of dry matter, relative to the weight of the web. Finally, it comprises a drying and crosslinking chamber, which has several temperature stages from 135 to 215°C, where the web is passed around with an average residence time of 30 seconds, or preferably slightly less than 30 seconds.

The production of the veil does not present any problems and is produced with a gram weight of 50 g/m ² , a thickness of 0.3 mm and a porosity of 1580 l/m ² /s.

The veil was subjected to mechanical strength testing at ambient temperature and high temperature, the results of which are shown in Table 1.

Resistance to pulling:

From the fleece sample, 10 test pieces are cut in the longitudinal direction and 10 test pieces in the transverse direction, which are 50 mm wide and 250 mm long. The test pieces are clamped between the jaws of a tensile machine and the pulling system of the moving jaw is operated until the test piece breaks. At this time, the breaking force in N and the elongation in percentage of the nominal length at break are read.

-7We perform the same strength measurement at 250°C with a fixed load equal to 20% of the previously measured breaking value and measure the time required for the sample to break.

Measuring resistance to tearing:

From the fleece sample, 10 test pieces are cut in the longitudinal direction and 10 test pieces in the transverse direction, each 50 mm wide and 100 mm long. On each test piece, starting from the short side, a small notch is made, parallel to the longer side, halfway along the longer sides and 50 mm long. On a tensile testing machine, the distance between the jaws is set to be 50 mm, the test pieces are mounted on the jaws and the dynamo is operated by setting the speed to 100 mm/N. The maximum load in N is read when the test piece is completely torn into two pieces. The resistance to tearing is given by the average of 10 measurements.

The first example of the veil shows very good mechanical and dimensional stability characteristics. It was applied to a bituminous membrane manufactured on a continuous production line by impregnating it with hot bitumen at about 200 °C, which tolerated the impregnation well and gave the membrane a very satisfactory aesthetic appearance.

First comparative example:

A web is prepared using only glass fiber as described in Example 1. The web has a grammage of 50 g/ ^m2 , a binder content of 24% by weight of dry matter relative to the weight of the web, a thickness of 0.3 mm and a porosity of 2000 l/ ^m2 /s. The web is subjected to the same mechanical tests as the web of Example 1.

Second comparative example:

Example 1 is reproduced with an organic fiber that does not meet the requirements of the invention. This is a polyester fiber marketed by the company TERGAL FIBRES under the reference 1.6 dtex T110 mi-mat coupé. It is also dispersible in water and is characterized by a titer of 1.6 dtex, a cutting length of 12 mm and a shrinkage rate of 7% at 130 ⁰ C in a steam atmosphere.

-8A veil is prepared which has a weight of 50 g/m ² , a binder content of 24 wt %, a thickness of 0.3-0.4 mm, and a porosity of 1700 l/m ² .s.

Production causes problems at the end of the line, as wrinkles can be observed at the exit from the drying chamber, which can be explained by the fact that heat shrinkage occurs in the organic fiber.

As mechanical tests show, the veil has a poor mechanical strength, which is worse than the classic glass veil. It can be stated that the anisotropy of the veil is strongly increased, and moreover, at 250 °C the mechanical strength disappears. Therefore, this veil is not suitable for making bituminous membranes.

Claims (9)

-9Patent claims: 1. A fiber-based web suitable for forming bituminous membranes and comprising glass fibers, organic fibers and a binder, characterized in that the organic fibers have a shrinkage rate of less than or equal to 5% at 130°C. 2. The web according to claim 1, characterized in that the shrinkage of the organic fibers at 130°C is less than or equal to 3%. 3. A web according to claim 1 or 2, characterized in that the organic fibers are based on a semi-crystalline polymer. 4. A web according to any one of claims 1 to 3, characterized in that the organic fibers are polyester fibers, in particular ethylene-polyterephthalate fibers. 5. A web according to any one of claims 1 to 4, characterized in that the organic fibers contain an oiling which enables the dispersion of the individual sub-components in water. 6. A veil according to any one of claims 1-5, characterized in that the proportion of organic fibers is 5-30% by weight relative to the total weight of the fibers. 7. A web according to any one of claims 1-6, characterized in that the binder content is in the range of 15-30% by weight, relative to the total weight of the web. 8. A web according to any one of claims 1-7, characterized in that it has a weight of 30-150 g/m ² . 9. A bituminous membrane having a coating base and being coated or impregnated with a bituminous matrix, characterized in that the base is a web according to claims 1-8. The authorized person DANUBIA Patent and Trademark Office Ltd. Kalmár Henriette Patent Attorney