Wiping blade for windscreen wiper

Abstract

Wiping sheet for a windshield wiper, at least a portion of which comprises a material based on (i) an elastomer containing natural rubber and ethylene-propylene-diene monomer (EPDM) and (ii) at least one additive, characterized in that the additive is at least one bio-based oil, the present invention relates to a fatty acid composition comprising free fatty acids and monoacylglycerols, diacylglycerols and triacylglycerols of fatty acids having a C28-C31 hydrocarbon chain and / or a C34-C36 hydrocarbon chain. The invention also relates to the use of the modified bio-based oil as a plasticizer and to a method for producing a wiper blade for a windscreen wiper.

Description

Technical Field

[0001] The present invention relates to a wiper blade for windscreen wipers, in particular a wiper blade consisting partly of a bio-based material, and also to a method for producing such a wiper blade. Background Art

[0002] Motor vehicles are usually equipped with a windscreen wiper system to wash and / or wipe the windscreen and prevent the driver's view of the surroundings from being obstructed. The windscreen wipers of such systems are usually driven by an arm that performs an angular back-and-forth movement. These wiper blades rub against the outer surface of the glass, such as the windscreen, removing water and moving it out of the driver's field of vision. In the traditional version, the wipers are manufactured in the form of an articulated yoke that holds the wiper blade at several points. In the more recent versions, known as "flat wiper blades", the wipers are manufactured in the form of a semi-rigid assembly that holds the wiper blade in place along its entire length.

[0003] Generally speaking, wipers are made from an elastically deformable material based on an elastomer to which additives are added, particularly to improve its mechanical properties, elasticity, wear resistance, and resistance to external corrosion, or to facilitate the manufacturing process. Examples include reinforcing fillers, plasticizers, vulcanizing agents, and agents that protect against UV radiation, oxidation, ozone, and / or wear. These additives are necessary to achieve a material with sufficient properties—especially mechanical strength and sliding properties—without generating excessive noise, to be used in the automotive industry.

[0004] In most cases, elastomers and additives are petrochemicals. However, the growing desire to protect the environment and reduce CO2 emissions has led to restrictions on the use of such petrochemicals.

[0005] In the rubber industry, natural rubber is used as a base elastomer, offering high performance in terms of elasticity and inherent mechanical properties. Natural rubber comes from rubber plantations and is a bio-based material. Combined with bio-based fillers and plasticizers, the use of natural rubber significantly reduces the proportion of petrochemical materials.

[0006] Application EP 3546302 describes a material for windscreen wiper blades in which the elastomer consists of a mixture of natural rubber, in particular unfunctionalized natural rubber, and EPDM (ethylene-propylene-diene monomer) of bio-based origin.

[0007] WO 2017 / 194776 describes a wiper blade for a windscreen wiper comprising a material based on natural rubber and at least one plasticizer which is a bio-based vegetable oil, for example sunflower oil.

[0008] The use of these materials makes it possible to prepare wipers with a reduced amount of raw materials of petroleum origin; wipers manufactured from these materials have good characteristics in terms of mechanical strength and sliding properties.

[0009] Typically, the wipes are manufactured from the produced mixture by compression in a mould or extrusion through a mould before vulcanisation begins. These materials are well suited for manufacturing wipes by a compression moulding process which involves vulcanisation at a temperature of about 180°C.

[0010] A particular problem arises when using extrusion as a manufacturing process. The crosslinking reaction temperature, for example in a salt bath, is typically around 200-210°C. At these temperatures, the bio-based oils present in the rubber compound will generate fumes, particularly due to their high volatility.

[0011] The resulting fumes will make the atmosphere in the production area unsafe. Furthermore, the vegetable oil will likely reach its flash point. At this temperature, the volume of gas formed will increase in pressure and, if it comes into contact with a heat source, such as an electric arc, will cause combustion.

[0012] For example, rapeseed oil has a flash point slightly above 200°C, which is very close to the salt bath temperature of 210°C. Using this oil would pose too great a risk of salt bath ignition.

[0013] Therefore, it is difficult to use bio-based vegetable oils in extrusion processes.

[0014] Therefore, the mixtures of elastomers and oils of vegetable origin described in the prior art are usually used in compression molding processes with relatively low temperature set points. Extrusion processes are performed using materials containing oils of petroleum origin with a flash point temperature above 220°C. Summary of the Invention

[0015] There is therefore a need to provide a composition comprising raw materials not originating from the petroleum industry, in particular bio-based plasticizers, which does not exhibit the above-mentioned drawbacks and which is suitable for use in a process for manufacturing windscreen wiper blades by extrusion.

[0016] The present inventors have now discovered that it is possible to prepare wipes in a process of this type using modified oils of plant origin.

[0017] The present invention therefore relates to a wiper blade for windscreen wipers, at least a portion of which comprises a material based on: (i) an elastomer comprising natural rubber and ethylene-propylene-diene monomer (EPDM), and (ii) at least one additive, characterised in that the additive is at least one bio-based oil comprising a C28-C31 hydrocarbon chain and / or a C34-C36 hydrocarbon chain.

[0018] The invention also relates to the use of such a bio-based oil as a plasticizer in a composition for wiper blades for windscreen wipers.

[0019] The present invention also relates to a method for producing a windshield wiper blade, comprising preparing a mixture of at least natural rubber, EPDM, and a plasticizer, the plasticizer being a bio-based oil containing C28-C31 hydrocarbon chains and C34-C36 hydrocarbon chains; subsequently extruding the mixture and then vulcanizing it at a temperature greater than or equal to 200° C. The method then comprises a step of recovering the vulcanized material to constitute at least a portion of the wiper blade.

[0020] The invention finally relates to a wiping blade for a windscreen wiper obtainable by such a method.

[0021] In particular, bio-based oils, particularly oils of plant origin, that have been treated to alter their physicochemical properties can be used in extrusion manufacturing processes at high temperatures.

[0022] The vegetable oil is notably chosen from sunflower oil, olive oil, rapeseed oil, linseed oil, coconut oil, castor oil, soybean oil and mixtures thereof.The modified bio-based oil according to the invention may in particular be sunflower oil.

[0023] Work-up may include filtration, oligomerization, hydrogenation and / or distillation steps.

[0024] Oils suitable for the practice of the present invention consist of a mixture of linear and branched long chain hydrocarbon compounds having typical molecular weights of C20, C30 and up to C36.

[0025] In particular, the oil contains C30 triacontan (melissa acid) chains and C36 hexatriacontan (hexatriacoate) chains.

[0026] This structure can be characterized by gas chromatography coupled to mass spectrometry (GC / MS). The modified bio-based oils useful according to the invention comprise a mixture of hydrocarbon compounds having long linear chains and therefore of the alkane type; this mixture advantageously comprises from 10% to 34% of C28-C31 chains and from 90% to 64% of C34-C36 chains, in particular from 10% to 30% of C28-C31 chains, and in particular a ratio of one third C28-C31 (including C30 triacontanes) and two thirds C34-C36 (including C36 hexatriacontanes).

[0027] Advantageously, the ratio between C28-C31 chains and C34-C36 chains is 1:2.

[0028] Preferably, the oil of biobased origin used as plasticizer according to the invention does not contain substantially free fatty acids or triglycerides, that is to say the content of these components in the oil is less than or equal to 0.1%, in particular less than or equal to 0.01%.

[0029] Processing oils or plasticizers of this type are characterized by a low degree of unsaturation, which can be measured by the iodine value method according to NF EN ISO 3961 or NF EN 14111 methods.

[0030] The iodine value is related to the amount of unsaturation. Specifically, for example, the greater the amount of iodine absorbed by the oil, the greater the amount of unsaturation, because the iodine chemically binds to the unsaturation during the experiment. On the other hand, an oil composed entirely of saturated fatty acids would have an iodine value of zero.

[0031] The iodine value of the oil is less than 40, in particular between 0.4 and 10, preferably between 0.5 and 2, preferably less than or equal to 1.5, more preferably less than or equal to 0.9.

[0032] In particular, the bio-based plasticizer according to the present invention has an iodine value of about 0.9. This level is almost comparable to the iodine value of polyalphaolefin plasticizers commonly used in rubber formulations for wipe applications (e.g., Durasyn 166 / INEOS), which are characterized by an iodine value of 0.1, or to the iodine value of commonly used and proven high-quality stearic acid, which has an iodine value of 0.4.

[0033] This characteristic suggests that chemical transformations have a considerable impact on the vegetable oils used as feedstock, which typically have much higher iodine values, such as sunflower oil, which has an iodine value of 127, or palm oil, which has an iodine value of 50, which is considered one of the most saturated oils. In comparison, rapeseed oil has an iodine value of 97 to 107.

[0034] The oil is fully compatible with rubber and EPDM and is characterized by a Hildebrand solubility parameter of 14 to 16 (J / cm 3 ) 1 / 2 This value is very close to that of natural rubber (NR) and EPDM, which are 16.6 and 15.8 (J / cm 3 ) 1 / 2 .

[0035] Advantageously, the pour point of the oil is less than or equal to -15° C., in particular a pour point of -25° C. In practice, the oil must remain fluid at low temperatures.

[0036] The flash point is higher than 270℃.

[0037] The boiling point is higher than 400℃.

[0038] From the perspective of its consistency, the oil behaves similarly to vegetable oil and may have a dynamic viscosity of about 50 to 60 cSt at 40°C according to DIN ISO 3104.

[0039] Advantageously, the modified oil is substantially free of sterols, vitamins, or residual fatty acids.

[0040] The present invention particularly relates to a method for producing a wiping blade for a windshield wiper, comprising:

[0041] a) preparing a mixture comprising at least natural rubber, EPDM and a plasticizer, said plasticizer being a bio-based oil comprising a C28-C31 hydrocarbon chain and a C34-C36 hydrocarbon chain as defined in the present description,

[0042] b) extruding the resulting mixture and then vulcanizing it at a temperature greater than or equal to 200° C.,

[0043] c) recovering the vulcanized material to form at least a portion of the wiper.

[0044] Such modified vegetable oils can be used in dual-material synthesis processes.

[0045] The process may notably comprise a step of peroxide vulcanization.

[0046] The additives to the material may further include at least one agent selected from fillers, antioxidants, and vulcanizing agents.

[0047] According to one embodiment of the invention, the EPDM is at least partly bio-based. The EPDM may thus contain up to 70% bio-based ethylene, preferably between 40% and 60%.

[0048] For the purposes of this invention, the term "biobased" refers to products that are not of fossil origin, but rather are obtained from renewable resources. Where applicable, it also refers to biological processes. The term "fossil-based" refers to any product derived from petroleum or coal or from petroleum or coal derivatives, in particular traditional fuel products derived from petrochemicals.

[0049] For example, bio-based ethylene can be produced from ethanol obtained from at least one plant material, in particular selected from sugar cane, sugar beets, woody plants or mixtures thereof.

[0050] Such blends of natural rubber and EPDM are described in patent application EP3546302.

[0051] In particular, an elastomer made from a blend of natural rubber and EPDM, half of which is produced from sugarcane ethanol, will be used.

[0052] Advantageously, the material comprises:

[0053] between 30 and 45% by weight of natural rubber, preferably between 35 and 40% by weight of natural rubber,

[0054] between 10 and 20% by weight of at least partially bio-based EPDM, preferably between 15 and 20% by weight of at least partially bio-based EPDM,

[0055] between 35% and 55% by weight of reinforcing filler, preferably between 40% and 45% by weight of reinforcing filler, and

[0056] Between 1 and 10% by weight of plasticizer, preferably between 2 and 5% by weight of plasticizer.

[0057] The wipe sheet material may comprise over 50% and up to 85% recycled and / or bio-based materials.

[0058] The composition may also contain one or more processing facilitators, particularly chemical-based lubricants such as stearic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The invention will be better understood from a reading of the following description, given by way of example only, and with reference to the accompanying drawings, in which:

[0060] Figure 1 A wiper blade for a windscreen wiper according to the invention is shown. DETAILED DESCRIPTION

[0061] according to Figure 1 The wiper blade 1 of the windscreen wiper according to the present invention has an elongated shape and is intended to be carried by a wiper body (not shown). The wiper blade 1 comprises a lip 3 and a root 5, which are connected by a hinge 7. The assembly of the lip 3, the root 5 and the hinge 7 forms the base of the wiper blade 1.

[0062] The root 5 allows the wiper blade 1 to be hooked into the wiper body. The lip 3 is designed to come into contact with the outer surface of a window, such as a windscreen, in order to wipe it.

[0063] The hinge 7 is formed from a thin strip of material which gives the wiper blade a certain flexibility and allows the wiper blade to tilt when the direction of movement of the wiper is changed, in other words, the lip tilts back and forth.

[0064] The wiper 1 is obtained by conventional manufacturing processes known to those skilled in the art.

[0065] Advantageously, at least a portion of the wipe 1 comprises a material as previously described; notably, the base of the wipe comprises such a material. Thus, embodiments can be envisaged in which, for example:

[0066] - Only lip 3 comprises this material,

[0067] - only the root 5 comprises this material,

[0068] - The entire wipe 1 comprises this material.

[0069] If desired, all or part of the surface of the wiper 1 may also be treated to modify it, for example by graphitization, plasma treatment, halogenation, ion implantation and / or coating. Such treatment enhances the mechanical properties, wiping properties and / or wear resistance of the wiper.

[0070] The wiper 1 can thus comprise a single or multiple coating layers. The coating layers cover the base of the wiper 1 .

[0071] Example 1: Preparation of composition

[0072] For illustrative purposes, examples of material formulations for the manufacture of wipes according to the invention are given here. Amounts are expressed as weight percentages and phr (parts per hundred parts of rubber).

[0073] The following formulation was produced in a 130 liter industrial Krupp mixer, enabling approximately 120 kg of the raw compound to be conveyed in the form of a continuous strand to feed the extruder.

[0074] [Table 1]

[0075]

[0076] Processing accelerators / anti-dispersants are mixtures of fatty alcohols, fatty acids and fatty acid esters, such as Aflux® 42 sold by Lanxess.

[0077] The antioxidant used in this example is 2,2,4-trimethyl-1,2-dihydroquinoline.

[0078] *The oil used is the product sold under the name Vivaspes 10227®

[0079] The wipes were then prepared in the following manner.

[0080] The composition is introduced into an extruder heated to 60-90°C in order to fully fluidize the material; the fluidized mixture is then forced through a die that will give it the final part geometry.

[0081] The profile leaving the die is then vulcanized in the presence of NaNO3 / NaNO2 or NaNO3 / KNO3 salts at a temperature reaching 210°C in a salt bath 20 to 30 m long.

[0082] By immersing the profile in this fluidized salt bed for a sufficient period of time, approximately 1 minute 30 seconds, the profile is stretched and forced through an oven so that the rubber is cured, that is, vulcanized, upon exiting this type of tunnel.

[0083] This operation is obviously carried out with the cover closed to avoid any emission due to vulcanization of the rubber.

[0084] However, if the cover is temporarily lifted and the behavior of the profile is observed when it is immersed in the salt bath, it can be observed that no smoke is generated when passing through the salt bath at 210°C.

[0085] Example 2

[0086] Evaluate the performance of materials.

[0087] The following performance is evaluated:

[0088] Mooney viscosity ML: According to ISO 289, determines the viscosity of the material in its original state to obtain good ability to be molded by extrusion

[0089] Shore A: The hardness of rubber according to ISO 868. To remove water from a windshield, a high scraping force is required. The hardness of the rubber used for wipers must be in the range of 55 to 70 Shore A points.

[0090] Mechanical properties are measured in tension / elongation mode according to ISO 37. This allows the determination of the modulus at 100% elongation (100% modulus) and the properties at break, resistance to break or modulus of rupture and elongation at break. These last two values ​​represent the ultimate properties of the rubber, as commonly expressed in the rubber industry.

[0091] 100% modulus (MPa) is a measurement related to the stiffness of the rubber wipe but under elongation.

[0092] International Rubber Hardness (IRHD) (pts) at 7 days / 85°C is measured according to ISO 48. Rubber tends to become harder or softer after being exposed to hot air at 85°C for a long time.

[0093] It is desirable to ensure that the hardness level remains stable with aging; the change must not exceed 3 hardness points.

[0094] Change in breaking strength (%) after 7 days at 85°C and change in breaking elongation (%) after 7 days at 85°C were measured according to ISO 37. These data allow the evaluation of a secondary result of hot air aging by measuring the loss in breaking strength.

[0095] Elongation set = The permanent set measured at 50% constant elongation after exposure to hot air at 85°C for 72 hours according to NF ISO 2285. At the end of the 72-hour period, the length of the specimen is measured. This length has increased relative to the initial length. Good properties correspond to the smallest possible difference.

[0096] The results are shown in the following table.

[0097] [Table 2]

[0098]

Claims

1. A wiper blade for a windshield wiper, at least a portion of which comprises a material based on: (i) an elastomer containing natural rubber and ethylene-propylene-diene monomer (EPDM), and (ii) at least one additive It is characterized by: The additive is at least one bio-based oil comprising a C28-C31 hydrocarbon chain and / or a C34-C36 hydrocarbon chain.

2. The wiping blade for a windshield wiper according to claim 1, characterized in that: The ratio between the C28-C31 chain and the C34-C36 chain is 1:

2.

3. The wiping sheet according to any one of claims 1 and 2, characterized in that The oil contains chains of the C30 triacontan type and chains of the C36 hexatriacontan type.

4. The wiping blade for a windshield wiper according to any one of claims 1 to 3, characterized in that: The iodine value of the oil is less than 40, in particular between 0.4 and 10, preferably less than or equal to 1.

5.

5. The wiping blade for a windshield wiper according to any one of claims 1 to 4, characterized in that: The oil has a 14 to 16 (J / cm 3 ) 1 / 2 Hildebrand solubility parameter.

6. The wiping blade for a windshield wiper according to any one of claims 1 to 5, characterized in that: The oil has a pour point less than or equal to -15°C.

7. The wiping blade for a windshield wiper according to any one of claims 1 to 6, characterized in that: The oil is a modified bio-based oil containing 10% to 34% C28-C31 chains and 90% to 64% C34-C36 chains.

8. The wiping blade for a windshield wiper according to any one of claims 1 to 7, characterized in that: The additives further include at least one agent selected from fillers, antioxidants, and vulcanizing agents.

9. The wiping blade for a windshield wiper according to any one of claims 1 to 8, characterized in that The EPDM contains up to 70% bio-based ethylene.

10. Use of a bio-based oil comprising a C28-C31 hydrocarbon chain and / or a C34-C36 hydrocarbon chain as defined in any one of claims 1 to 7 as a plasticizer in the composition of a windscreen wiper blade.

11. A method for preparing a wiping blade for a windshield wiper, characterized in that: The method comprises: a) preparing a mixture comprising at least natural rubber, EPDM and a plasticizer, said plasticizer being a bio-based oil comprising a C28-C31 hydrocarbon chain and / or a C34-C36 hydrocarbon chain as defined in any one of claims 1 to 7, b) extruding the mixture obtained and then vulcanizing it at a temperature higher than or equal to 200° C., in particular peroxide vulcanizing it, c) recovering the vulcanized material to form at least a portion of the wiper.

12. A wiping blade for a windscreen wiper obtainable by the method according to claim 11.

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