PL202476B1 - Glass fibre mat and use thereof for built-up roofing - Google Patents

Abstract

The invention relates to a fiber-based screen for use in the production of bituminous membranes, comprising glass fibers, organic fibers and a binder, the organic fibers having a shrinkage coefficient at 130°C of less than or equal to 5%. The invention also relates to the use of a screen for the production of a bituminous membrane comprising a substrate coated, covered or saturated with bitumen, in which the substrate is the above screen. The screen and membrane are used to produce coverings and/or seals. PL PL PL PL

Description

The present invention relates to the field of fiber-based sheet materials and more particularly relates to a glass screen used as a substrate in the manufacture of coated, coated or impregnated products with bitumen, particularly for use as a covering and / or sealant.

The use of bituminous membranes for a covering or sealing surface is known in the field of coatings or seals. The membranes usually consist of a sheet substrate coated with or impregnated with bituminous mass.

Sheet materials can come from a variety of origins and are usually made of organic or mineral fibers, preferably in the form of a non-woven fabric.

Among the materials used, glass screens are of great interest as they guarantee dimensional stability over time when applied to a bituminous membrane.

Glass screens can be produced by any known technique, particularly the so-called wet process, as detailed in the reference work The Manufacturing Technology of Continnous Glass Fibers, KL LOEWENSTEIN, Ed. ELSEVIER, 2nd ^e edition, 1983, pp 315-317. This technique, similar to papermaking techniques, consists in creating an aqueous suspension of chopped glass fibers, laying the suspension in the form of a film on a suction mat under suction to remove some of the water from the applied film, applying a binder composition to the wet film, drying the screen and cross-linking the binder in a dryer then on the screen packaging as desired. The end product is in the form of fairly thin sheets (thickness of the order 0.2 to 0.8 mm) usually stored in the form of rolls.

The binder is often an aqueous composition based on urea formaldehyde resin which withstands a temperature suitable for subsequent bitumen impregnation.

Glass screens, however, suffer from a relatively low tear strength, which reduces the convenience of use and forces the user, in particular, to be careful when handling the membrane in its manufacture or laying on the roof.

To overcome this disadvantage, composite substrates are used, which consist of a screen based on organic fibers having good tear strength and a glass mesh giving the overall dimensional stability. These complexes combining two intermediates, however, require complex preparation.

The invention aims to provide a glass based material whose tear strength is improved and its manufacture is not more complex than that of a conventional screen.

EP-A-O 763505 describes a glass fiber mat for the production of bituminous roof shingles, the strength of which is improved by a urea-formaldehyde binder modified with a vinyl self-crosslinking additive. In this mat, a minor proportion may not be glass fibers, but selected from organic fibers such as Nylon®, polyester, polyethylene, polypropylene. This document does not provide specific information on these organic fibers and does not contain any specific example explaining this possibility.

The present invention is based on the discovery that many organic fibers are not beneficial for the fabrication of the screen and even have a very negative effect on the screen properties when used for bituminous coverings, but a very careful selection of synthetic materials overcomes these drawbacks.

The present invention relates to a fiber-based screen used in the manufacture of bituminous membranes having an isotropic or random structure comprising glass fibers, organic fibers and a binder, the organic fibers having a shrinkage factor at 130 ° C less than or equal to 5%. Preferably, the organic fibers have a shrinkage factor of less than or equal to 3% at 130 ° C.

According to the invention, the basis of organic fibers is a semi-crystalline polymer.

Organic fibers are polyester fibers, especially polyethylene terephthalate.

Preferably, the organic fibers contain a lubricant that allows the individual individual fibers to be dispersed in water.

According to the invention, the proportion of organic fibers is in the order of 5 to 30% by weight, based on the total weight of the fibers.

The proportion of binder is in the order of 15 to 30% by weight in relation to the total weight of the screen.

PL 202 476 B1

According to the invention, the screen weight is from 30 to 150 g / m2. The invention also relates to the use of the screen previously described for the production of a bituminous membrane comprising a substrate coated, coated or impregnated with bituminous mass, the substrate being said screen.

According to the invention, the term "glass screen" includes materials well known to those skilled in the art of glass fiber products. This is the case for thin sheet materials which are substantially isotropic in structure, that is to say that they do not have a predominant fiber orientation.

In practice, the shield can be determined by the "isotropy ratio", the machine direction tensile strength of the machine direction screen tensile strength of typically about 1, particularly in the order of 1 to 1.5, and sometimes up to 2. This fiber orientation essentially random is usually achieved by the presence of staple glass fibers for producing the screen, for example according to the wet process technique mentioned above.

The selection of organic fibers according to the above criterion gives the screen a good quality, in particular a mechanical and thermal strength compatible with the subsequent use of bitumen impregnation, while other fibers give the screen insufficient thermal and / or mechanical resistance.

First, the organic fibers used to make the screen have an elevated melting point to avoid their decomposition in all the thermal stages of screen fabrication, especially during drying and cross-linking in the dryer and when handling the screen, especially in contact with the bituminous binder. Generally, the synthetic organic material is selected such that its melting point is greater than about 220 ° C.

According to the invention, the fibers are selected on the basis of their thermal shrinkage coefficient: this value is related to the dimensional variation in the form of the shortening of the fiber after it has been exposed to a given temperature for a certain time. To this end, the initial fiber length Li before heating is measured and then the final fiber length Lf, and the shrinkage factor r is equal to:

r = (Li-Lf) / Li (percent)

The shrinkage coefficients determined according to the invention are determined at a temperature of 130 ° C generated in a steam atmosphere for a period of 30 minutes.

According to the invention, a shrinkage of less than or equal to 5%, preferably 4%, especially 3%, for example of the order of 2 to 3%, is selected.

Advantageously, this fiber quality can be obtained by using semi-crystalline polymeric materials, in particular those whose drawing method allows to obtain an elongation increasing the crystallinity index. Other manufacturing conditions, such as the presence of nucleating agents or the temperature factor, can also lead to the ordering of the primary macromolecules such that the polymer with an initially amorphous structure begins to acquire a crystalline structure and become semi-crystalline.

Fibers meeting the requirements of the invention can be found among polyester fibers, especially polyalkylene terephthalate and especially polyethylene terephthalate.

Organic fibers which are adapted to wet fiber methods and which contain a lubricant which enables the individual filaments to be dispersed in water are preferred.

The organic fibers may vary in size with a mean diameter in the order of 7 to 25 μ ^ ι, and a titer of 0.5 to 2 dtex. The fibers are preferably cut to a length in the order of one or several tens of millimeters, especially from 6 to 30 mm.

The effect of organic fibers is well appreciable from 5% by weight based on the total weight of the fibers. The proportion of organic fibers is preferably in the order of 5 to 30%, in particular 20 to 30% and especially about 25% by weight, based on the total weight of the fibers.

The glass fibers used according to the invention for the production of the screen are of the conventional type, preferably in the form of staple fibers in the order of tens of millimeters, in particular from 6 to 30 mm, especially about 10 to 20 mm, for example 12 to 18 mm. It is understood that a certain proportion of the fibers (e.g. 5 to 10%) can be cut to lengths up to 100 mm. Moreover, a continuous fiber, especially glass fiber, can be introduced into the screen as a reinforcement in the longitudinal direction.

The binder used in the manufacture of the screen is preferably based on urea formaldehyde resin, preferably modified with vinyl and / or acrylic additives in a manner known per se.

Especially from US-4,681,802, EP-A-0 763505. The proportion of binder is usually from 15 to 30% by weight of dry substance, based on the weight of the screen.

₂

The screen is prepared with a weight of typical glass screen, of the order of 30 to 150 g / m ^2, particularly from 50 to 120 g / m ^2.

Taking into account the difference in the density of glass fibers and organic fibers, the amount of substance in the screen according to the invention, for a given grammage, is slightly larger than in the glass screen, which results in its thickness being relatively greater and / or less porous. The porosity is, for example, on the order of 1500 to 1900 l / m2 for a 50 g / m2 screen.

The screen according to the invention is particularly suited for sealing and / or coating applications.

The bituminous mass can be chosen from among the known masses: natural, modified or unmodified bitumen, or a synthetic binder, such as a "light binder", making it possible in particular to impart a decorative color to the membrane.

The following examples illustrate the invention without limiting it.

P r z k ł a d 1

An aqueous suspension of fibers is prepared, in which the fibers are:

- 75% by weight of cut E glass fiber with a monofilament diameter of 10 μm and a linear mass of 360 dtex, the cutting length is 12 mm,

- 25% by weight of chopped polyester fiber, available from KURARAY, EP 133 symbol, suitable for paper processes, dispersible in water. This fiber has a monofilament diameter of 12 µm, a linear weight of 1.4 dtex, and a cut length of 15 mm. It is a polyethylene terephthalate fiber, drawn to increase its crystallinity, having a shrinkage factor of 2% at 130 ° C in a humid environment with an exposure of 30 minutes and a shrinkage ratio of 3% at 170 ° C in a dry atmosphere with an exposure of 15 minutes.

The fiber suspension, also containing the usual additives such as antifoam, dispersing, viscosity increasing, is processed under standard conditions in a screen fabricator comprising (i) a hydroforming device to form a partially dehydrated wet film, (ii) application station adhesives by spraying, coating (using the device "cascade" or "curtain coating") or passing through a bath with a water composition based on urea-formaldehyde resin softened with acetate and acrylic compound, applying to the screen an amount of binder 19% by weight of dry substance in relation to weight of the screen, (iii) a drying and cross-linking dryer with multiple temperature zones from 135 to 215 ° C, where the screen circulates, with an average residence time of 30 seconds, preferably slightly less than 30 seconds.

₂

Manufacture of the screen does not present any problems, it is obtained with a weight of 50 g / m ^2, a thickness of 0.3 mm and a porosity of 1580 l / m ² .s.

The screen is subjected to mechanical strength tests at ambient temperature and high temperature, and the test results are given in Table 1 below.

Tensile strength

10 samples are cut from the screen sample in the longitudinal direction and 10 samples in the transverse direction, 50 mm wide, 250 mm long. The specimen is clamped between the jaws of the stretching machine and the drive of the movable chuck is engaged until the specimen breaks: the breaking force (in Newtons) and elongation at break (in percent of the nominal length) are read.

The tensile strength is also measured at 250 ° C, under a constant load of 10% of the breaking force value determined previously, and the time until the sample breaks is measured.

Tear strength

10 samples are cut from the screen sample in the longitudinal direction and 10 samples in the transverse direction, 50 mm wide and 100 mm long. On each sample, a distinct incision is made on the edge of the short side, parallel to the long sides halfway between the larger sides and 50 mm long. On the stretching machine, the distance between the jaws is adjusted to 50 mm, the sample is locked in the jaws and the dynamometer is actuated setting the climb speed to 100 mm / min. The maximum load (in N) is read when the sample is completely divided in two. The tear strength is expressed as the mean value of the ten measurements.

PL 202 476 B1

The screen of example 1 has very satisfactory mechanical properties and dimensional stability. It was introduced into a continuous line for producing bituminous membranes by impregnating with hot bitumen at a temperature of about 200 ° C, showing good impregnation suitability and even giving the membrane a very satisfactory aesthetic appearance.

Comparative example 1

The screen is prepared on the basis of only the glass fiber as described in Example 1. The screen has a basis weight of 50 g / m, the proportion of binder 24% by weight of dry] substance relative to the weight of the screen, thickness of 0.3 mm and a porosity of 2000 l / m ² . s. It is subjected to the same mechanical tests as the screen in example 1.

Comparative example 2

Example 1 is repeated with an organic fiber that does not meet the criteria of the invention. It is a polyester fiber sold by TERGAL FIBRES with the symbol 1.6 dtex T110, semi-matt cut, also dispersible in water, marked as 1.6 dtex, cut length 12 mm, shrinkage factor at 130 ° C in a steam atmosphere equal to 7%.

The screen is prepared with a weight of 50 g / m, involving 24% by weight of the binder, of a thickness of 0.3 to 0.4 mm and a porosity of 1700 l / m ^2. s.

Manufacturing is problematic at the end of the line as it is found to form a fold as it exits the dryer which may be related to the thermal shrinkage phenomenon of the organic fiber.

As indicated by mechanical tests, the screen is characterized by low mechanical strength, lower in relation to the classic glass fiber screen. In particular, it has been found that the screen anisotropy is significantly increased. In addition, it has no mechanical strength at 250 ° C.

This screen is not suitable for the manufacture of bituminous membranes.

T a b l i c a 1

Ex. 1 Ex. see 1 Ex. see 2 Tensile strength Longitudinal (N / 5cm) 214 165 150 Transverse (N / 5cm) 133 93 70 Anisotropy 1.6 1.7 2.1 Elongation (%) 1.9 1.1 1.2 Tear strength Longitudinal (N) 3.0 1.5 3.2 Transverse (N) 3.5 1.7 3 Strength at 250 ° C > 4 min > 4 min 0 Fold on the line No No Yes

The invention describes in detail the case of manufacturing a screen of a certain grammage, by a wet method, for use in the production of bituminous membranes, but it should be understood that the invention is not limited to this manufacturing method and particularly covers other screen manufacturing techniques (dry method), other screen qualities, optionally continuous glass fiber reinforced as well as other products used as coverings and / or seals.

Claims (9)

1. A fiber-based screen used in the manufacture of bituminous membranes having an isotropic or random structure, including glass fibers, organic fibers and a binder, characterized in that the organic fibers have a shrinkage factor at 130 ° C less than or equal to 5%. The screen according to claim 1, characterized in that the organic fibers have a shrinkage factor of less than or equal to 3% at a temperature of 130 ° C. The screen according to claim 1 or 2, characterized in that the basis of the organic fibers is a semi-crystalline polymer. PL 202 476 B1 The screen according to any one of claims 1-3, characterized in that the organic fibers are polyester fibers, especially polyethylene terephthalate. 5. Screen according to any one of claims 1-4, characterized in that the organic fibers contain a grease that enables the dispersion in water of the individual individual fibers. The screen according to any one of claims 1-5, characterized in that the proportion of organic fibers is in the order of 5 to 30% by weight in relation to the total weight of the fibers. The screen according to any one of claims 1-6, characterized in that the proportion of binder is in the order of 15 to 30% by weight with respect to the total weight of the screen. The screen according to any of claims 1-7, characterized in that its basis weight is from 30 to 150 g / m ² . 9. Use of a screen as defined in any one of claims 1-8 for the manufacture of a bituminous membrane comprising a coated, coated or impregnated substrate, the substrate being said screen.