COMPOSITE COMPRISING A PLASTISOL MATRIX AND AN ADHESION PROMOTER

Abstract

The invention relates to a composite based on at least one textile reinforcement element embedded in a polyvinyl chloride-based matrix, a plasticizer, a thermal stabilizer and a phenol-aldehyde resin based on: at least one aromatic polyphenol comprising at least one trivalent aromatic ring bearing at least one hydroxyl function and a group comprising a function selected from a hydroxyl function and a methoxy function, and at least one hardening agent.

Description

Title of the invention: COMPOSITE COMPRISING A PLASTISOL MATRIX AND AN ADHESION PROMOTER Technical field of the invention

[0001] The present invention relates to the field of composites based on a plastisol and a textile element and to products comprising such composites. Previous art

[0002] Plastisols are pastes obtained from a colloidal dispersion of a resin in powder form in a liquid plasticizer. These pastes are gelled by cooking and used in numerous applications such as fabric coating, the manufacture of hollow bodies, or the coating of metal surfaces. The adhesion of the plastisol to its substrate, particularly textile substrates, is an important characteristic for the lifespan of the articles using it.

[0003] Several adhesion promoters have been proposed to improve the adhesion of a PVC (polyvinyl chloride) plastisol-based matrix to textile elements.

[0004] Document FR 2 304 464 describes a reinforcing band comprising a multiplicity of parallel textile filaments embedded in a polyvinyl chloride plastisol comprising a binder intended to improve adhesion to the filaments by forming a condensation resin containing formaldehyde, in particular the association of resorcinol and hexamethylenetetramine (HMT).

[0005] US patent 4,623,686 describes a PVC plastisol comprising polyisocyanates in order to limit the increase in viscosity while ensuring proper adhesion to textile materials such as polyamides or polyesters. Patent WO2016 / 137738, for its part, proposes the use of a mixture of an isocyanurate and an organophosphate.

[0006] Another solution for improving the adhesion of textile elements to a PVC plastisol-based matrix is ​​to use a bonding layer, for example, an adhesive applied to one or more contact surfaces, and numerous adhesive formulations have been proposed. However, this solution involves additional steps of coating the surface(s), as well as taking into account the specific crosslinking dynamics of the adhesives and the gelation of the plastisol.

[0007] Continuing its research, the applicant discovered that a resin based on a specific methylene acceptor and a hardener improved adhesion performance without impacting the stability of the plastisol, thus facilitating its use in forming composites and promoting the di The invention addresses known health, safety, and environmental issues related to the raw materials used in the resin. The composite material, which allows the use of bio-based compounds, helps reduce pressure on fossil resources. Detailed description of the invention

[0008] The invention relates to a composite based on at least one textile reinforcement element embedded in a polyvinyl chloride (PVC)-based matrix, a plasticizer, a thermal stabilizer, and a phenol-aldehyde-based resin:

[0009] of at least one aromatic polyphenol comprising at least one trivalent aromatic ring bearing at least one hydroxyl function and a group comprising a function selected from a hydroxyl function and a methoxy function, and

[0010] of at least one hardening agent.

[0011] Definitions

[0012] In the present, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0013] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition can thus be in a totally or partially gelled state or in a non-gelled state.

[0014] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from greater than a to less than b (that is, excluding the bounds a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (that is, including the strict bounds a and b). In the present case, when an interval of values ​​is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably designated.

[0015] The carbon-containing compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. This includes, in particular, polymers, plasticizers, fillers, etc.

[0016] PVC Matrix

[0017] The composite according to the invention is based on a polyvinyl chloride-based matrix, a plasticizer, a thermal stabilizer and a phenol-aldehyde resin.

[0018] The PVC-based matrix and a plasticizer is known to those skilled in the art under the name "plastisol", which is a paste obtained by colloidal dispersion of a powdery synthetic resin, in this case a PVC powder, in a liquid plasticizer.

[0019] The plasticizer's main role is to improve the flexibility and resistance to impact and cold of PVC by reducing interactions between polymer chains and lowering the glass transition temperature (Tg). This temperature, which is between 75 and 85°C for rigid PVC, can reach -40°C for flexible PVC. The addition of plasticizer, which can represent up to 50% of the final mass of the material, improves its elongation at break.

[0020] This type of plasticizing is therefore often preferred by manufacturers. Thus, during external plasticizing, the plasticizer is inserted between the polymer chains and acts as a "solvent." The plasticizer and the polymer are then bound by Van der Waals type electrostatic interactions. These interactions occur between the chlorine atoms of the PVC and the electrophilic groups of the plasticizers, and their intensity depends in particular on the polarity of the plasticizer.

[0021] The plasticizer can be any plasticizer commonly used in the field of plastisols and is preferably chosen from phthalates, dicarboxylic aliphatic acid esters, epoxides and phosphates.

[0022] The polyvinyl chloride-based matrix of the composite according to the invention also includes a thermal stabilizer.

[0023] The role of thermal stabilizers is to bind the hydrogen chlorides released during dehydrochlorination, an autocatalytic reaction due to heat, light, and oxygen. Thus, the stabilizers prevent secondary reactions during the processing of PVC and also increase its thermal stability.

[0024] The thermal stabilizer can be any thermal stabilizer commonly used in the field of plastisols, and is preferably chosen from lead-based stabilizers, tin-based stabilizers or calcium / zinc or calcium / organic stabilizer mixtures.

[0025] Aromatic polyphenol

[0026] The PVC-based matrix of the composite according to the invention comprises a phenol-aldehyde resin based on at least one aromatic polyphenol comprising at least one aromatic trivalent ring bearing at least one hydroxyl function and a group comprising a function selected from a hydroxyl function and a methoxy function, and a hardening agent.

[0027] The expression "phenol-aldehyde resin based on" should of course be understood to mean a resin comprising the mixture and / or the product of the reaction between the various basic constituents used for the final condensation of this resin, of The term "basic constituents" refers only to the product of the reaction between the various basic constituents used for this resin. Some of these constituents may be intended to react, or are likely to react, with each other or with their immediate chemical environment, at least partially, during the various phases of the manufacturing process of the composition, composites, or an article comprising this composition or these composites, particularly during a curing step. Thus, the basic constituents are the reactants intended to react together during the final condensation of the resin and are not reactants intended to react together to form these basic constituents.

[0028] In a preferred arrangement, the aromatic polyphenol is a lignin compound.

[0029] In another preferred arrangement, the aromatic polyphenol has three hydroxyl groups in meta positions relative to each other, the two ortho positions of at least one of the hydroxyl groups being unsubstituted. In this preferred arrangement, the aromatic polyphenol is preferably phloroglucinol.

[0030] Hardener

[0031] The PVC-based matrix of the composite according to the invention comprises a phenol-aldehyde resin based on at least one aromatic polyphenol and a hardening agent.

[0032] Preferably, the hardening agent content in the PVC-based matrix ranges from 0.5 to 15% relative to the weight of PVC, preferably from 0.5 to 5% relative to the weight of PVC.

[0033] Any hardener suitable for crosslinking the aromatic polyphenol compound used in the PVC matrix of the composite according to the invention may be used as a hardening agent. In particular, the hardening agent may be chosen from among aldehyde compounds.

[0034] Preferably, the hardening agent is an aldehyde compound, for example, a compound such as 5-(hydroxymethyl)furfural, or an aromatic dialdehyde compound. Such an aldehyde compound is highly advantageous because it avoids the production of formaldehyde, unlike conventional methylene donors. An aromatic dialdehyde is a compound comprising at least one aromatic ring, this aromatic ring bearing at least two aldehyde groups.

[0035] In a preferred arrangement, the aromatic dialdehyde compound is an aldehyde of formula A: zXx (A) rV H

[0036] in which X comprises N, S or O and R represents -CHO.

[0037] According to a preferred embodiment, X represents O. The aromatic dialdehyde compound then has the formula Bb: HH

[0038] In this embodiment, the aromatic dialdehyde compound is preferably 2,5-furanedicarboxaldehyde.

[0039] In another preferred embodiment, X comprises N. In a variant of this embodiment, X represents NH. The aromatic dialdehyde compound then has the formula Ca: H

[0040] Preferably, in this variant, the aromatic dialdehyde compound is 2,5-IH-pyrroledicarboxaldehyde.

[0041] In another variant of this embodiment, X represents NR1 with RI representing a radical chosen from the group consisting of alkyl, aryl, arylalkyl, alkylaryl, and cycloalkyl radicals. The aromatic dialdehyde compound then has the formula Cb: RI (Cb) H

[0042] In another preferred embodiment, X comprises S. In a variant of this embodiment, X represents S and the aromatic dialdehyde compound then has the formula Da: H

[0043] Preferably, in this variant, the aromatic dialdehyde compound is 2,5-thiophenedic arboxaldéhy de.

[0044] In another variant of this embodiment, X represents SR2 with R2 representing a radical chosen from the group consisting of alkyl, aryl, arylalkyl, alkylaryl, and cycloalkyl radicals. The aromatic dialdehyde compound then has the formula Db:

[0045] In another variant of this embodiment, X represents R3-S-R2, with R2 and R3 each independently representing a radical chosen from the group consisting of alkyl, aryl, arylalkyl, alkylaryl, and cycloalkyl radicals. The aromatic dialdehyde compound then has the formula De: R3 (From) rV H

[0046] In another variant of this embodiment, X represents S=O. The aromatic dialdehyde compound then has the formula Dd: O (Dd) H

[0047] In another variant of this embodiment, X represents O=S=O. The aromatic dialdehyde compound then has the formula De: .0 (From) H

[0048] Among the different embodiments described above, preference will be given to the embodiments and variants in which X represents NH, S or O. In these embodiments and variants, R, which represents the -CHO group, will preferably be in position 5 and the -CHO group in position 2 on the aromatic ring.

[0049] Preferably, the two meta positions of at least one aldehyde function of the hardening agent are unsubstituted.

[0050] Most preferably, the aromatic aldehyde is chosen from the group consisting of 1,4-benzene-dicarboxaldehyde, 1,3-benzene-dicarboxaldehyde, 2,5-furanedicarboxaldehyde and mixtures of these compounds, and most preferably 1,4-benzene-dicarboxaldehyde.

[0051] Preferably, the hardening agent is chosen from a carbamide, 5-(hydroxymethyl)furfural, 1,4-benzene-dicarboxaldehyde and the 1,3-benzene-dicarboxaldehyde, preferably chosen from 1,4-benzene-dicarboxaldehyde and 1,3-benzene-dicarboxaldehyde.

[0052] Additives

[0053] The PVC-based matrix of the composite according to the invention may also include all or part of the usual additives and processing agents known to those skilled in the art and commonly used in plastisol compositions, such as pigments or protective agents.

[0054] Preferably, the PVC-based matrix of the composite according to the invention does not comprise isocyanate compounds or comprises less than 5% by weight relative to the weight of PVC, preferably less than 2% by weight, preferably less than 1% by weight and most preferably less than 0.5% by weight.

[0055] Reinforcing element

[0056] The composite according to the invention comprises at least one textile reinforcement element. A textile reinforcement element is made of an organic material, in particular a polymer, or an inorganic material, such as for example glass, quartz, basalt or carbon.

[0057] The textile reinforcement element may be wire-like, that is to say, have a length at least 10 times greater than the largest dimension of its cross-section, regardless of the shape of the latter: circular, elliptical, oblong, polygonal, in particular rectangular, square, or oval. In the case of a rectangular cross-section, the textile reinforcement element has the form of a strip.

[0058] The textile reinforcement element can also be in the form of a film, that is to say, it extends in two main directions and has a very small thickness compared to each of its other main dimensions, at least 100 times smaller, preferably at least 1000 times smaller.

[0059] The textile reinforcing element may be a basic textile monofilament. This basic textile monofilament is obtained, for example, by melt spinning, solution spinning, or gel spinning. Each basic textile monofilament is made of an organic material, in particular a polymer, or an inorganic material, such as glass, quartz, basalt, or carbon. The polymeric materials may be thermoplastic, such as aliphatic polyamides, in particular polyamide 6-6, and polyesters, in particular polyethylene terephthalate. The polymeric materials may be non-thermoplastic, such as aromatic polyamides, in particular aramid, and cellulose, both natural and artificial, in particular rayon. Each basic textile monofilament preferably has a substantially circular cross-section with a diameter ranging, for example, from 2 µm to 100 µm.

[0060] The textile reinforcement element can be an assembly of several monofilaments textile components as defined above, also called a strand. A strand preferably comprises more than 10 elementary textile monofilaments, preferably more than 100 elementary textile monofilaments and more preferably more than 500 elementary textile monofilaments.

[0061] The textile reinforcement element can also be an assembly of several strands as defined above.

[0062] The textile reinforcement element is preferably of the polyester type, advantageously of the polyethylene terephthalate, polyamide, glass, carbon, quartz or basalt type.

[0063] According to a preferred embodiment, the composite according to the invention comprises a multiplicity of reinforcing elements as defined above arranged side by side along a principal direction.

[0064] According to another preferred embodiment, the composite comprises several fibers assembled in a knit or fabric.

[0065] Knitting refers to an assembly of textile reinforcement elements as defined above, comprising stitches formed by one or more of these textile reinforcement elements. Each stitch comprises a loop interlaced with another loop. Examples include jersey or English rib knits for knitted fabrics and charmeuse or atlas knits for knitted fabrics with cast-on stitches.

[0066] By fabric, we mean an assembly of textile reinforcement elements either in an ordered manner, in which a first family of reinforcement elements, called warp elements, substantially parallel to each other and extending along a first principal direction, and a second family of reinforcement elements, called weft elements, substantially parallel to each other and extending along a second principal direction are assembled together, the warp elements passing successively over and under the weft elements according to a pattern defining the weave of the fabric, or in a disordered, or random, manner, so as to form a non-woven fabric.

[0067] In a preferred embodiment, which can be associated with any reinforcement element configuration described above, the reinforcement element consists of at least two different materials (so-called "hybrid" element) chosen from an organic material, in particular polymeric, or an inorganic material, such as for example glass, quartz, basalt or carbon.

[0068] Reinforced product

[0069] The invention also relates to a reinforced product comprising at least one composite according to the invention or a semi-finished article according to the invention.

[0070] The reinforced product is preferably a product comprising at least one composite according to the invention embedded in a rubber composition matrix.

[0071] Said rubber composition matrix is ​​based on at least one elastomer, diene or non-diene (for example thermoplastic). It is preferably a crosslinked or crosslinkable type composition, that is to say, it includes a crosslinking system, in particular a vulcanization system, adapted to allow crosslinking of the composition during its curing, or during the curing of the finished product in which the composite is incorporated.

[0072] Such a reinforced product may be chosen in particular, but not exclusively, from conveyor belts, transmission belts, tracks, tires for pneumatic or non-pneumatic wheels.

[0073] A pneumatic tire is defined as a tire made capable of supporting a load by virtue of being pressurized by a gas, generally air. A non-pneumatic tire is defined as a tire made capable of supporting a load by means other than pressurization, for example by means of stays.

[0074] Manufacturing process

[0075] The invention also relates to a method for manufacturing a composite according to the invention comprising at least the steps of:

[0076] Mixture of the aromatic polyphenol with a portion of the plasticizer sufficient to solubilize said aromatic polyphenol at a temperature between 100°C and 150°C

[0077] Mixing polyvinyl chloride powder with a fraction of the plasticizer to obtain a homogeneous paste;

[0078] Addition of the thermal stabilizer and the rest of the plasticizer to the polyvinyl chloride paste;

[0079] Incorporation of the solubilized aromatic polyphenol into the polyvinyl chloride paste at room temperature;

[0080] Incorporation of the hardening agent into the polyvinyl chloride paste at room temperature. Examples

[0081] Preparation of compositions

[0082] Each composition shown in Table 1 is prepared by mixing the components at low speed in a blender equipped with a dough hook at room temperature until a homogeneous dough is obtained.

[0083] The PVC powder is first introduced into the blender, then a small amount of liquid plasticizer is mixed with the powder until a homogeneous paste is obtained. Finally, the remaining plasticizer and the thermal stabilizer are added.

[0084] Part of the plasticizer is used to solubilize resorcinol or phloro-glucinol at 130°C, before introduction into the plastisol mixture described above. The hardening agent is introduced last into the composition.

[0085] The plastisol mixture is then kept in an airtight container at room temperature for 24 h before preparing the test specimens.

[0086] Viscosity measurement

[0087] After the preparation of the different compositions, the viscosity is measured immediately after preparation (viscosity "at 0 days") and after 14 days.

[0088] Viscosity is measured using a Brookfield / Mobil No. 62 / LV-02 type viscometer according to the following protocol: the sample is transferred into the temperature-controlled chamber up to approximately 150 mL (inner beaker graduation), taking care to avoid the formation of air bubbles. The sample is allowed to regulate itself at the measurement temperature of 23°C for the specified time, i.e., 1 to 20 minutes, depending on the initial temperature of the composition. In a manner known to those skilled in the art, the speed is selected, for example, 10 rpm or 30 rpm, and the spindle is set to rotate. The axis is allowed to stabilize (1 minute) before taking the first reading, and the result is read from the digital display (viscosity in cP).

[0089] Preparation of test tubes

[0090] A PET yarn made up of 8 strands of 1100 dTex is attached on either side of a mold made up of two parts, each part comprising a cavity in the shape of a half-cylinder, and is held under low tension by means of a weight and screws, without altering the torsion of the yarn.

[0091] The two parts of the mold are heated separately to 160°C. The composition to be tested is then deposited into each of the semi-cylindrical cavities. The mold is left open for 5 minutes at 160°C, allowing for pre-gelation. The mold is then closed and pressed at 200 kN for 20 minutes to form a cylindrical specimen, with the filament passing through the cylinder along its axis. Once the mixture has gelled, the mold is cooled to room temperature before removing the specimens. The specimens are stored at room temperature for at least 24 hours before being tested.

[0092] Measurement of pull-out forces

[0093] To measure the pull-out force of the yarn from the composition, the PET yarn is pulled out of the cylindrical block using a tensile testing machine according to the method described in ASTM D 2229-02. The pulling speed is 250 mm / min. The adhesion of the composition to the reinforcement is thus characterized by the force required to pull the reinforcement out of the specimen at a temperature of 23 °C.

[0094] [Tables 1] Compositions (as % of PVC) Tl T2 Cl C2 PVC (1) 100 100 100 100 Plasticizer (2) 7'7 77 7^' 77 Thermal stabilizer (3) 4 4 4 4 Resorcinol (δ) 0 1.6 0 δ Phloeoglucinol (6) 0 0 1.9 1.9 Hexamine dispersion (4) 0 2.4 δ -4 δ G Terephthalaldehyde (7) 0 0 0 9 Results Pull strength at 23°C (base 100) 100 111 161 139 Viscosity at 23°C δ0 mm. 2650 2200 3050 Viscosity <cp>at 14 days nm 2609 2188 3300

[0095] (1) Vinnolit PVC, “P 4472”

[0096] (2) phthalate-type plasticizer, “Reofos” from the Lanxess company

[0097] (3) thermal stabilizer for PVC, “AKCROSTAB LZB6159” from the company Valtris

[0098] (4) dispersion of Hexamine in a chlorinated paraffin from the company PolyBlend UK

[0099] (5) Resorcinol (CAS no. 108-46-3) from Sigma Aldrich

[0100] (6) Phloroglucinol (CAS No. 108-73-6) from Sigma Aldrich

[0101] (7) Terephthalaldehyde (CAS No. 623-27-8) from Sigma Aldrich

[0102] Compositions according to the invention exhibit improved adhesion performance and low evolution over time.< / cp>

Claims

Demands

1. Composite based on at least one textile reinforcement element embedded in a polyvinyl chloride-based matrix, denoted PVC, a plasticizer, a thermal stabilizer and a phenol-aldehyde resin based on: • at least one phloroglucinol compound or a lignin compound, and • at least one hardening agent selected from a carbamide, 5-(hydroxymethyl)furfural, 1,4-benzene-dicarboxaldehyde and 1,3-benzene-dicarboxaldehyde.

2. Composite according to claim 1 in which the hardening agent is selected from 1,4-benzene-dicarboxaldehyde and 1,3-benzene-dicarboxaldehyde.

3. Composite according to any one of the preceding claims wherein the hardening agent content in the PVC-based matrix ranges from 0.5 to 15% by weight of PVC, preferably from 0.5 to 5% by weight of PVC.

4. Composite according to any one of the preceding claims wherein the textile reinforcement element comprises a material selected from aliphatic polyamides, polyesters, aromatic polyamides, cellulose, glass, quartz, basalt or carbon and mixtures thereof.

5. Composite according to the preceding claim in which the textile reinforcement element comprises a material selected from aliphatic polyamides, polyesters, aromatic polyamides and cellulose and mixtures thereof.

6. Composite according to claim 4 in which the textile reinforcement element comprises a material selected from glass, quartz, basalt or carbon.

7. Composite according to any one of the preceding claims comprising a multiplicity of textile reinforcement elements arranged side by side along a principal direction.

8. Composite according to any one of claims 1 to 7 comprising several fibers assembled into a knit or fabric.

9. Reinforced product comprising at least one composite according to one any of claims 1 to 8.

10. Reinforced product according to the preceding claim selected from conveyor belts, transmission belts, tracks, tires for pneumatic or non-pneumatic wheels.

11. A method for manufacturing a composite according to any one of claims 1 to 8 comprising at least the steps of: • Mixing phloroglucinol or a lignin compound with a portion of the plasticizer sufficient to solubilize said phloroglucinol or lignin compound at a temperature between 100°C and 150°C; • Mixing polyvinyl chloride powder with a fraction of the plasticizer to obtain a homogeneous paste; • Adding the heat stabilizer and the remainder of the plasticizer to the polyvinyl chloride paste; • Incorporating the solubilized phloroglucinol or lignin compound into the polyvinyl chloride paste at room temperature; • Incorporation of the hardening agent chosen from a carbamide, 5-(hydroxymethyl)furfural, 1,4-benzene-dicarboxaldehyde and 1,3-benzene-dicarboxaldehyde into the polyvinyl chloride paste at room temperature;• Embedding of at least one textile reinforcement element.