Patent ID: 12187642

In a preferred embodiment the method of the present invention further comprises, between step (c) of drying and step (d) of shaping, a step of blending thermosetting mineral wool (binding fibers) with virgin mineral wool and/or with recycled mineral wool and/or with natural organic fibers (non-binding fibers).

The natural organic fibers are non-thermoplastic fibers, of plant or animal origin. The plant fibers are preferably selected from the group consisting of lignocellulosic fibers and cotton fibers. The lignocellulosic fibers are preferably selected from wood fibers, hemp fibers, flax fibers, sisal fibers, cotton fibers, jute fibers, coco fibers, raffia fibers, abaca fibers, cereal straw or rice straw. The animal fibers are preferably selected from the group consisting of animal wools, such as sheep's wool.

This blending can in principle be implemented by any appropriate mechanical and/or pneumatic means. The inventors have found that the mechanical properties of the final insulation products were better the longer the blending method preserved the length of the blended mineral fibers. Indeed, when the blending step leads to a considerable reduction in the size of the fibers, this results in less mineral fiber entanglement and lower tensile strength of finished products. In a preferred embodiment of the method of the invention, the blend of binding fibers and non-binding fibers is implemented by means of a stream of compressed air passing through a swirl chamber. Such a device makes it possible indeed to obtain highly regular blends without excessively reducing the length of the fibers.

When the blend of the two types of fibers uses a pneumatic means it is important to ensure that the stream of compressed air is at a low enough temperature to prevent a possible softening of the organic binder.

Indeed, in a preferred embodiment of the method of the invention, the dried organic binder forming the organic sheath surrounding the fibers of the thermosetting mineral wool has thermoplastic behavior, that is to say, it softens or liquefies when it is heated to a certain temperature, referred to hereinafter as “softening temperature” or “glass transition temperature”, determined by differential scanning calorimetry (DSC). This softening temperature is greater than the drying temperature but less than the crosslinking onset temperature of the binder. This softening advantageously grants a certain tack to the fibers which thus become capable of adhering to one another and also to non-binding mineral fibers (virgin/recycled mineral wool) or to natural organic non-binding fibers, optionally present. The inventors have observed that whereupon the dry organic binder fluidifies enough when hot, it migrates even from the fibers of thermosetting mineral wool to the fibers of the virgin/recycled mineral wool or to the natural organic fibers. When inspecting under optical microscopy the insulation products obtained by blending 50% by weight of thermosetting mineral wool and 50% by weight of virgin mineral wool, the inventors have observed the presence of organic binder on all the fibers and not only on half of them.

The respective proportions of thermosetting mineral fibers (binding fibers) and virgin/recycled mineral fibers or natural organic fibers can vary within rather broad ranges. These ranges are dependent, among others, on the homogeneity of the blend of fibers and on the thermosetting binder content of the binding fibers. The greater the uniformity of the blend and the higher the thermosetting binder content of the binding fibers, the higher the proportion of non-binding virgin/recycled fibers or natural organic fibers can be.

Generally, 100 parts by weight of thermosetting mineral wool is blended with 10 to 400 parts by weight, preferably with 20 to 300 parts by weight, in particular with 30 to 200 parts by weight of virgin and/or recycled mineral wool (non-binding mineral wool) or natural organic fibers.

In a particularly advantageous embodiment, the method for manufacturing insulation products based on mineral wool bound by an organic binder thus comprises the following seven successive steps:providing mineral wool at room temperature,applying, to the mineral wool, an aqueous thermosetting binder composition,drying the mineral wool impregnated with the aqueous thermosetting binder composition to obtain thermosetting mineral wool,blending the thermosetting mineral wool with virgin and/or recycled mineral wool or with natural organic fibers,shaping the blend of thermosetting mineral wool and virgin and/or recycled mineral wool or natural organic fibers, andheating the shaped blend at a temperature for long enough to enable the constituents of the binder to crosslink and an insoluble binder to be formed.

The step of shaping the thermosetting mineral wool (or the blend of thermosetting mineral wool and virgin and/or recycled mineral wool or natural organic fibers) is preferably carried out by molding and/or compression. The mold used for molding the products must be made of a material capable of withstanding the temperature of the thermosetting step. It must also have a structure that allows the hot air from the curing oven to easily penetrate the molded product. The mold can for example consist of a box-shaped metal screen. The metal-screen box is preferably filled with a volume of loose thermosetting mineral wool that is greater than its capacity and is then closed by a metal-screen cover. The thermosetting mineral wool thus is more or less compressed depending on the excess filling volume. This excess filling volume of the box by the thermosetting mineral wool is for example comprised between 10% and 150%, preferably between 15 and 100% and in particular between 20 and 80%.

When the method of the present invention is a continuous method, the shaping of the thermosetting mineral wool can be done for example by compression by means of a roller located at the inlet of the curing oven on a conveyor.

The step of setting the shaped thermosetting mineral wool by heating it at a temperature for long enough to enable the constituents of the binder to be condensed (polymerization/crosslinking) and an insoluble binder to be formed is carried out under conditions that are familiar to a person skilled in the art. When the method is a continuous method, the curing oven is advantageously identical to the oven of a line for manufacturing insulation products of the prior art, wherein very hot compressed air is passed through the mat of mineral wool.

The heating temperature of step (e) is advantageously comprised between 130° C. and 240° C., preferably between 180° C. and 230° C., in particular between 190° C. and 220° C. The heating time is advantageously comprised between 30 seconds and 15 minutes, preferably between 1 minute and 10 minutes, in particular between 2 and 8 minutes.

It is easy to adjust the density and the thickness of the insulation products based on mineral wool obtained by the method of the present invention by varying the compression rate of the thermosetting mineral wool during the curing step. The insulation products generally have a density comprised between 4 and 150 kg/m3, preferably between 5 and 60 kg/m3, in particular between 6 and 40 kg/m3. Their thickness is generally comprised between 20 mm and 500 mm, advantageously between 40 mm and 300 mm, preferably between 50 mm and 200 mm, and in particular between 60 mm and 150 mm.

The method for manufacturing insulation products based on mineral wool disclosed hereinbefore can in principle be implemented with any thermosetting organic binder currently used in the field of mineral wools.

Examples of such binders include those that arebased on resole resins (phenol-formaldehyde), preferably modified with urea,based on Maillard reagents (reducing sugars and amines),based on acrylic polymers and crosslinking agents such as polyhydroxylated and polyaminated reagents,based on non-reducing sugars and/or hydrogenated sugars and polycarboxylated reagents, such as citric acid,based on aminoamides obtained by reaction of carboxylic anhydrides and alkanolamines.

The binder is preferably formaldehyde-free and advantageously comprises biosourced reagents, renewable in the short term. In one advantageous embodiment, the aqueous binder composition comprises more than 50% by dry weight of biosourced reagents.

These biosourced reagents are selected for example from saccharides and saccharide hydrogenation products. The aqueous binder compositions additionally contain a crosslinking agent that is typically a polycarboxylic acid, preferably citric acid. The reaction between the saccharides and the saccharide hydrogenation products and the polycarboxylic acid is advantageously catalyzed by a catalyst, especially by sodium hypophosphite (HPS).

Thermosetting binder systems for mineral wool based on reducing saccharides, non-reducing saccharides and/or hydrogenated sugars and polycarboxylic acids are disclosed in detail in international applications WO2009/080938, WO2010/029266, WO2013/014399, WO2013/021112 and WO2015/132518 in the name of the applicant.

To the applicant's knowledge, the intermediate product obtained at the end of step (c) of the method of the invention, that is to say the thermosetting mineral wool formed from mineral fibers surrounded by a dry, thermosetting organic layer, in thermal equilibrium with their environment, has not been disclosed beforehand in the prior art.

As a result, the present application also relates to loose thermosetting mineral wool containing binding mineral fibers surrounded by a dry layer of thermosetting organic binder and, optionally, non-binding fibers. This mineral wool is loose, that is to say that it consists of individual fibers that can interlace, but which do not adhere to one another so as to form a mat of fibers.

This thermosetting mineral wool is not sticky because the organic binder layer on the surface of the fibers does not contain water and thus is not an aqueous viscous composition of an organic binder.

Furthermore, this thermosetting mineral wool is in thermal equilibrium with its environment, that is to say that it is not in the process of cooling (for example after fiberizing) or heating (for example in the oven).

The thermosetting mineral wool of the present invention is a stable intermediate product that can be stored, transported and transformed under environmental conditions of temperature and relative humidity.

It can consist exclusively of binding fibers (mineral fibers surrounded by a layer of thermosetting organic binder) or else contain both binding fibers and non-binding fibers. In the latter case, the non-binding fibers are advantageously selected from fibers of virgin mineral wool and/or fibers of recycled mineral wool and/or natural organic fibers, as defined and disclosed hereinbefore.

When the loose thermosetting mineral wool of the present invention is a blend of binding fibers and non-binding fibers it generally comprises 10 to 400 parts by weight, preferably 20 to 300 parts by weight, in particular 30 to 200 parts by weight of virgin and/or recycled mineral wool (non-binding mineral wool) or natural organic fibers per 100 parts by weight of thermosetting mineral wool.