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EP-4741567-A1 - SYNTHETIC LEATHER BASED ON POLYVINYL CHLORIDE REINFORCED WITH CITRUS AND/OR PRICKLY PEAR VEGETABLE FIBRES FOR USE IN THE ROAD, RAIL, MARITIME TRANSPORT AND FURNITURE SECTORS

EP4741567A1EP 4741567 A1EP4741567 A1EP 4741567A1EP-4741567-A1

Abstract

The invention relates to a synthetic leather based on polyvinyl chloride (PVC) reinforced with vegetable fibres derived from citrus and/or prickly pear, suitable for use in the road, rail, maritime transport and furniture sectors. The leather comprises at least three layers, wherein a first skin layer contains, per 100 parts of PVC, from 3 to 15 parts by weight of at least one vegetable fibre and from 30 to 50 parts by weight of at least one (cyclo)alkyl-based plasticiser; and second and third layers, identical or different, contain, per 100 parts by weight of PVC, from 10 to 40 parts by weight of at least one vegetable fibre and from 80 to 120 parts by weight of at least one (cyclo)alkyl-based plasticiser, and a blowing agent. The vegetable fibres are obtained from citrus and/or prickly pear and impart improved mechanical, thermal and light resistance to the material, enabling the manufacture of eco-sustainable synthetic leathers with reduced environmental impact and high durability.

Inventors

  • SANTANOCITO, Adriana Maria
  • MAZZETTI, STEFANO
  • MERIGHI, ROBERTO

Assignees

  • Ohoskin S.r.l.

Dates

Publication Date
20260513
Application Date
20251105

Claims (10)

  1. A synthetic leather based on polyvinyl chloride reinforced with citrus and/or prickly pear vegetable fibres for use in the road, rail, maritime transport and furniture sectors, said leather comprising at least three layers, wherein: a. a first layer, referred to as the skin layer, comprises, per 100 parts of PVC, from 3 to 15 parts by weight, preferably from 5 to 10 parts by weight, of at least one vegetable fibre and from 30 to 50 parts by weight of at least one (cyclo)alkyl-based plasticiser; b. a second and a third layer, having identical or different compositions, comprise, per 100 parts by weight of PVC, from 10 to 40 parts by weight, preferably from 15 to 35 parts by weight, of at least one vegetable fibre and from 80 to 120 parts by weight of at least one (cyclo)alkyl-based plasticiser, and a blowing agent; and wherein the at least one vegetable fibre is selected from a fibre derived from citrus, a fibre derived from prickly pear pads, or a mixture thereof.
  2. The synthetic leather according to claim 1, wherein the vegetable fibre has a moisture content equal to or lower than 12% by weight, preferably equal to or lower than 8% by weight.
  3. The synthetic leather according to any one of claims 1-2, wherein the leather contains a citrus-derived fibre having an ADL lignin content (van Soest) of less than 10% by weight, preferably less than 7% by weight; an ADF fibre content (van Soest) greater than 14% by weight, preferably greater than 16% by weight; and an NDF fibre content (van Soest) greater than 24% by weight, preferably greater than 28% by weight.
  4. The synthetic leather according to any one of claims 1-2, wherein the leather comprises a prickly pear-derived fibre obtained from pads older than three years and not older than seven years, preferably not older than five years.
  5. The synthetic leather according to claim 4, wherein the prickly pear-derived fibre has an ADL lignin content according to van Soest of less than 6% by weight, preferably less than 5% by weight; an ADF fibre content according to van Soest greater than 20% by weight, preferably greater than 24% by weight; and an NDF fibre content according to van Soest greater than 20% by weight, preferably greater than 24% by weight.
  6. The synthetic leather according to any one of claims 1-5, wherein the plasticiser of the first layer consists of 50-100% by weight of a dialkyl ester of 1,2-cyclohexane dicarboxylic acid and 0-50% by weight of an epoxidised fatty acid.
  7. The synthetic leather according to any one of claims 1-6, wherein the plasticiser used in the second and third layers consists of 80-100% by weight of a dialkyl ester of 1,2-cyclohexane dicarboxylic acid and 0-20% by weight of an epoxidised fatty acid.
  8. The synthetic leather according to any one of claims 1-7, wherein the citrus fibres are calcined fibres.
  9. The synthetic leather according to any one of claims 6-7, wherein the plasticiser is a mixture of diisononyl ester of 1,2-cyclohexane dicarboxylic acid and epoxidised soybean oil.
  10. The synthetic leather according to any one of claims 1-9, wherein the citrus fibres contain less than 2% by weight of particles having a diameter greater than 400 µm.

Description

Field of the invention . The present invention relates to a synthetic leather based on polyvinyl chloride reinforced with citrus and/or prickly pear vegetable fibres and comprising an (cyclo)alkyl-based plasticiser. The synthetic leather according to the invention exhibits highly ecological characteristics while maintaining extremely high performance properties. Background of the invention . A major trend in industry in general, and in particular in the automotive, railway, maritime and furniture industries, is the use of materials, and thus finished products, made from raw materials that result in a reduced carbon footprint and minimise the consumption of natural resources. . Polyvinyl chloride (PVC) is an extremely versatile plastic material, also used as a main component in the formulation of synthetic leathers. From a chemical standpoint, PVC is an amorphous thermoplastic polymer and therefore exhibits a characteristic structural rigidity, which is lost only above its glass transition temperature (approximately 80 °C), when it begins to soften and gradually becomes more fluid as the temperature increases. In order to render PVC liquid at lower temperatures, plasticising agents are used which interpose themselves between the polymer chains (solvation), reducing the strength of the intermolecular bonds and thereby making the PVC flexible at temperatures at which it would otherwise be too rigid (ambient temperature). Typically, up to 30% by weight of plasticiser is added relative to the PVC. . In the automotive, railway, maritime and furniture sectors, synthetic leathers are normally based on PVC. This is because PVC ensures high durability of the leather, a feature that is essential for use in components typical of the aforementioned industries, which are often expected to last for more than ten years. In fact, the only alternative to PVC is polyurethane, which, however, degrades much more rapidly. . It is therefore necessary to develop PVC-based synthetic leathers having a lower environmental impact. Document US 2022/025576 discloses a foamed PVC-based synthetic leather comprising, in addition to PVC, a lignocellulosic-based material and expandable microspheres. Summary of the invention The present invention relates to a PVC-based synthetic leather comprising at least one alkyl- or cycloalkyl-based plasticiser and at least one vegetable fibre. Detailed description of the invention The at least one vegetable fibre is preferably a citrus fibre and/or a prickly pear fibre, used alone or in combination, having the following characteristics. A moisture content lower than 12% by weight, preferably lower than 8% by weight. For citrus fibres, an ADL lignin (van Soest) content lower than 10% by weight, preferably lower than 7% by weight; an ADF fibre content higher than 14% by weight, preferably higher than 16% by weight; an NDF fibre content higher than 24% by weight, preferably higher than 28% by weight. For citrus sources, it is preferable to use fibres dried by the addition of calcium oxide (so-called "calcined" fibres). For citrus fibres, preferably not more than 2% by weight of the powder shall have a particle size above 400 µm. The prickly pear fibres are preferably obtained from pads older than three years and not older than seven years, more preferably not older than five years, which are sufficiently fibrous without being excessively lignified. The prickly pear fibre has an ADL lignin content (van Soest) lower than 6% by weight, preferably lower than 5% by weight; an ADF fibre content (van Soest) higher than 20% by weight, preferably higher than 24% by weight; an NDF fibre content (van Soest) higher than 20% by weight, preferably higher than 24% by weight. For prickly pear powders (which are more fibrous and tend to form "needles" of nonuniform length), not more than 2% by weight of the powder shall have a particle size above 600 µm, preferably with an average diameter D50 of about 100-200 µm, more preferably about 150 µm. As regards the plasticisers used within the scope of the invention, they must be nonvolatile, chemically inert towards PVC, stable to heat and light, and resistant to oxidation. Preferably, they should also be non-flammable, odourless and colourless. Various commercial types exist, mostly containing phthalates, which perform well but are suspected of being carcinogenic, and have been extensively investigated under a risk-assessment process conducted by the European Community and subsequently regulated under REACH, being therefore subject to strict limitations. To avoid such issues, also perceived negatively from a commercial standpoint, it is preferable to use non-phthalate plasticisers such as: Cyclohexane esters (DINCH): the most commonly used is the diisononyl ester of 1,2-cyclohexane dicarboxylic acid. It has an excellent toxicological profile, low viscosity, low density, excellent low-temperature flexibility, low volatility, good migration and extraction resistance. It is soluble