Method for controlling the crosslinking time for a silicone gel that gives off a volatile organic substance

Abstract

The present invention relates to a method for preparing a silicone gel that gives off a volatile organic substance, the method comprising the following steps: 1) providing a part A comprising (i) from 10% to 89.99% by weight of a dihydroxy PDMS polymer that has a viscosity measured at 25°C of between 3000 and 100,000 cSt (mm2 / s) and (ii) from 10% to 90% by weight of a mixture including a volatile solvent capable of solubilising the dihydroxy polydimethylsiloxane polymer and a volatile organic substance; 2) providing a part B comprising (iii) from 10% to 30% by weight of MMT and (iv) from 70% to 90% by weight of a non-functionalised polydimethylsiloxane silicone oil that has a viscosity measured at 25°C of between 10 and 245 cSt (mm2 / s) capable of solubilising N-morpholinomethyl triethoxysilane; 3) preparing a mixture comprising from 95% to 99% by weight of part A and from 1% to 5% by weight of part B; characterised in that part A also comprises from 0.01% to 5% by weight of a carboxylic acid and does not comprise a metal catalyst, and a gel that can be obtained by this method and the kit for implementing this method.

Description

Method for controlling the crosslinking time of a silicone gel diffusing volatile organic substance Technical field

[0001] The present invention relates to the field of articles used for perfuming or deodorizing the atmosphere or laundry, or as insect repellents or insecticides, which comprise a solid polymeric material containing a volatile organic substance. More particularly, the present invention relates to a transparent anhydrous silicone gel diffusing volatile organic substances, said gel not comprising a reinforcing agent or a toxic catalyst and having the advantage of having an easily controllable crosslinking time. Prior art

[0002] Many types of devices exist to release and / or diffuse volatile organic substances into the environment, such as perfume, molecules to absorb unpleasant odors, or insecticides. These devices can take different forms adapted to their uses and can be obtained in different ways. Generally, these products are made of an organic matrix (particularly polymeric) such as silicone.

[0003] Different technologies currently exist for producing this type of organic polymer matrix, in particular matrices obtained from silicone elastomers in which one or more volatile organic substances are dispersed.

[0004] A preferred type of silicone elastomer is cold vulcanizable (CV) silicone elastomers formulated from reactive polydimethylsiloxanes (PDMS) of varying degrees of polymerization. Crosslinking occurs at room temperature using a crosslinking agent that reacts with the reactive groups of the polysiloxane chains and a catalyst that controls the crosslinking. The elastomer is either single-component (CV1) or two-component with one of the two parts containing the catalyst (CV2, also called RTV for "Room Temperature Vulcanization"). When the product is single-component, the polymerization reaction is activated by the product's contact with moisture in the air. When the product is two-component, crosslinking is not activated by moisture in the air. It begins when the two components are mixed together.

[0005] Japanese Patent No. 82-40,558 describes the process for manufacturing a silicone elastomer matrix for diffusing perfume into the atmosphere. The composition silicone elastomer is mixed with the perfume and then by adding an organometallic salt, the crosslinking of the composition is triggered in a mold. The matrix thus obtained has a non-linear diffusion of the perfume due to an incompatibility of the polymer and the perfume composition.

[0006] European Patent No. EP2247318 describes a transparent anhydrous gel in the form of a crosslinked silicone network, comprising one or more volatile substances, in particular perfume and non-volatile substances, and not comprising any filler or reinforcing agent. The crosslinking of the silicone gel is obtained by the presence of a metallic catalyst such as tin, titanium or platinum.

[0007] However, many of these devices have notable drawbacks. For example, the use of catalysts, particularly metallic ones, makes these devices potentially hazardous to the environment due to their toxicity. Other devices require fillers or reinforcing agents, which have the disadvantage of making the gels opaque or increasing their hardness. Some devices are opaque once formed, which makes them less attractive to consumers who want transparent products. For other types of devices, the problem will be related to the quantity of volatile organic substance, which will be limited and therefore less effective in space and time.

[0008] The biggest problem faced by manufacturers is that silicone-type polymer RTV matrices, obtained by mixing two separate parts, require a very high crosslinking time when very little crosslinking agent is added, which is difficult to manage on an industrial scale. Today, manufacturers require technology that allows them to control the crosslinking time of polymer matrices as they wish, and more specifically to accelerate said crosslinking time, while using a very small amount of crosslinking agent (which is necessary in order to obtain a gel that is not opaque and does not give off an unpleasant fishy odor). Summary

[0009] This disclosure improves the situation as presented above while resolving several technical issues.

[0010] Indeed, the Applicant discovered that the addition of a very small quantity of carboxylic acid in a two-part system to manufacture an organic polymeric matrix also called hereinafter silicone gel, made it possible to control the crosslinking time of said system.

[0011] Thus, the present invention relates to a process for preparing a silicone gel diffusing volatile organic substance prepared using a two-component cold-vulcanizable silicone elastomer not comprising a metal catalyst, and the crosslinking time of which can be controlled.

[0012] More specifically, a first subject of the present invention relates to a process for preparing a silicone gel diffusing volatile organic substance, said process comprising the following steps: 1) Providing a Part A comprising (i) from 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity measured at 25°C between 3000 and 100000 cSt (mm 2 / s) and (ii) from 10% to 90% by weight of a mixture including a volatile solvent capable of solubilizing the dihydroxy PDMS polymer and a volatile organic substance; 2) Providing a Part B comprising (iii) from 10% to 30% by weight of MMT and (iv) from 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity measured at 25°C between 10 and 245 cSt (mm 2 / s) capable of solubilizing MMT; 3) Preparation of a mixture comprising from 95% to 99% by weight of part A and from 1% to 5% by weight of part B; characterized in that part A also comprises from 0.01% to 5% by weight of a carboxylic acid and does not comprise a metal catalyst.

[0013] A second subject of the present invention relates to a silicone gel capable of being obtained by the process which is the subject of the present invention, characterized in that it does not comprise a metal catalyst.

[0014] A third subject of the present invention relates to the use of a carboxylic acid in a process for preparing a silicone gel diffusing volatile organic substance from a two-component cold-vulcanizable silicone elastomer to control the crosslinking time of said elastomer.

[0015] A fourth object of the present invention relates to a kit for implementing the method according to the present invention, characterized in that it comprises: - a part A comprising (i) from 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity measured at 25°C between 3000 and 100000 cSt (mm 2 / s) and (ii) from 10% to 90% by weight of a mixture including at least one volatile solvent capable of solubilizing the dihydroxy PDMS polymer and a volatile organic substance; - a part B comprising (iii) from 10% to 30% by weight of MMT and (iv) from 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity measured at 25°C between 10 and 245 cSt (mm 2 / s) capable of solubilizing MMT; characterized in that Part A also comprises from 0.01% to 5% by weight of a carboxylic acid and does not comprise a metal catalyst and in that Part A and Part B are physically separated from each other. Brief description of the drawings

[0016] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1

[0017] [Fig. 1] shows the effect of adding myristic acid on crosslinking time. Fig. 2

[0018] [Fig. 2] shows the molar ratio of carboxylic acid / N-Morpholinomethyl triethoxysilane (MMT). Detailed description of embodiments of the invention

[0019] The volatile organic substance-diffusing silicone gel according to the present invention is a gel obtained from a two-component system that is crosslinkable at room temperature (RTV). Such systems are typically packaged in two distinct and physically separate parts, namely a part comprising a crosslinkable silicone elastomer (part A) and a crosslinking part (part B). The silicone gel is prepared by mixing the two parts together and then allowing the gel to form, for example in a mold. The crosslinkable silicone compositions according to the present invention are functionalized silicone polymers.

[0020] According to the present invention, the volatile organic substance diffusing silicone gel is prepared as follows: 1) Providing a Part A comprising (i) from 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity measured at 25°C between 3000 and 100000 cSt (mm 2 / s) and (ii) from 10% to 90% by weight of a mixture including a volatile solvent capable of solubilizing the dihydroxy PDMS polymer and a volatile organic substance; 2) Providing a Part B comprising (iii) from 10% to 30% by weight of MMT and (iv) from 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity measured at 25°C between 10 and 245 cSt (mm 2 / s) capable of solubilizing MMT; 3) Preparation of a mixture comprising from 95% to 99% by weight of Part A and from 1% to 5% by weight of Part B; Part A also comprising from 0.01% to 5% of a carboxylic acid and not comprising a metal catalyst.

[0021] Gel means a homogeneous elastic composition forming a network having a relative resistance of less than 20 g / mm, in particular less than 15 g / mm, preferably less than 10 g / mm. The relative resistance to gel is measured at 25°C using a texturometer.

[0022] For example, the RHEO company's TA-XT Texturometer can be used in the "compressive force measurement" mode using a Stable Micro Systems SMS P / 6 6 mm stainless steel cylindrical probe; test speed 0.50 mm / sec; target mode: distance; rupture mode: Rate; and rupture sensitivity 5.0 g.

[0023] Part A

[0024] Part A comprises from 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity measured at 25°C between 3000 and 100000 cSt (mm 2 / s) (measured at 25°C). In the context of the present invention, said functionalized silicone polymers are polydimethylsiloxanes functionalized at their two ends by a hydroxyl group (also called dihydroxy PDMS) having a viscosity of between 3000 and 100000 cSt (mm 2 / s). Their viscosity measured at 25°C can be between 3000 and 75000 cSt (mm 2 / s), between 3000 and 50000 cSt (mm2 / s), between 3000 and 35000 cSt (mm 2 / s), between 3000 and 10000 cSt (mm 2 / s), between 3000 and 9000 cSt (mm 2 / s), between 4000 and 8000 cSt (mm 2 / s), between 5000 and 7000 cSt (mm 2 / s). Preferably, the dihydroxy PDMS polymer has a viscosity measured at 25°C approximately equal to 6000 cSt (mm 2 / s). The viscosity of the dihydroxy PDMS polymer, which is expressed as kinematic viscosity in cSt (mm 2 / sec), is measured as dynamic viscosity (units Pa-sec) at 25 °C using a TA Instruments Discovery HR-2 rheometer and the standard method provided by DIN 53019 (2008) (including their calibration), and then converted from dynamic viscosity to kinematic viscosity by dividing the former by the density of the dihydroxy PDMS polymer.

[0025] The advantage of the present invention over existing systems is that said system does not require the addition of a metal catalyst to carry out crosslinking, in particular a tin catalyst.

[0026] Additionally, Part A comprises from 10% to 90% by weight of a mixture including a volatile solvent capable of solubilizing the dihydroxy PDMS polymer and a volatile organic substance.

[0027] A "volatile organic substance" means a product containing one or more organic molecules, which has a vapor pressure greater than atmospheric pressure at room temperature, i.e. 25°C. The substance The volatile organic compound used according to the invention may be chosen from a perfume, an odor-masking agent or an insecticide. Preferably, it is a perfume.

[0028] The fragrance may be selected from a large number of odoriferous compounds. The fragrance according to the invention may be one or a combination of several odoriferous compounds. Such odoriferous compounds are mentioned, for example, in S. Arctander, “Perfume and Flavor Chemicals” (Montclair, NJ, 1969), or in “Common Fragrance and Flavor Materials,” Wiley-VCH, Weinheim, 2006.

[0029] Non-limiting examples of the latter are compounds belonging to the following families: o aromatic, terpene and / or sesquiterpene hydrocarbons, in particular essential oils containing these molecules and in particular essential oils of citrus fruits (lemon, orange, grapefruit, bergamot), nutmeg, etc., o aromatic alcohols and in particular benzyl alcohol, phenylethyl alcohol and phenylpropyl alcohol, o alcohols and in particular non-aromatic cyclic or acyclic, saturated or unsaturated, primary, secondary or tertiary linalool, citronellol, geraniol, nerol, dihydromyrcenol, terpineol and fatty alicyclic alcohols whose chain contains from 4 to 10 carbon atoms, o aldehydes and in particular saturated and unsaturated alicyclic fatty aldehydes whose carbon chain contains from 4 to 12 carbon atoms carbon, aromatic aldehydes such as cinnamaldehyde,alpha-amylcinnamaldehyde and aromatic aldehydes of alpha-hexylcinnamaldehyde, lilial and phenolics such as vanillin and ethylvanillin, o phenols and in particular aromatic phenols such as eugenol and isoeugenol, as well as methyl ethers thereof, o carboxylic acid esters, in particular acetic esters of benzyl alcohol, geraniol, citronellol, nerol, terpineol, borneol or linalool, o aromatic acid esters such as benzoates and salicylates, as well as cinnamates esterified with alcohols of the aliphatic series containing a chain of 1 to 6 carbon atoms, o phenol aromatic acids mainly in their aromatic lactone form, such as coumarin and dihydrocoumarin, o alcohol carboxylic acids in their lactone form, and dodeca-lactones, more particularly octa-, undeca- and gamma, delta-, undeca-, delta- and delta-dodeca-lactones in their saturated or unsaturated form, o macrocyclic compounds in which the carbon chain contains from 12 to 16 carbon atoms, o ethers and acetals in their acyclic or cyclic form, and in particular aromatic and non-aromatic aldehyde acetals containing a carbon chain of 4 to 10 carbon atoms, as well as cyclic ethers of substituted furfuran and substituted or unsubstituted pyran, o heterocyclic compounds containing one nitrogen atom, and in particular indole derivatives, as well as heterocyclic compounds containing 2 nitrogen atoms, and in particular those of the pyrazine series, o ketones,in particular aromatic ketones such as 4 (p-hydroxyphenyl)-2-butanone and cyclic or acyclic, saturated or unsaturated non-aromatic ketones and in particular those of the pyrazine series, o aromatic or non-aromatic sulfides, disulfides and mercaptans.,

[0030] The term "odor masking agent" or "odor neutralizing agent" means an agent capable of reducing or eliminating the perception of a bad odor generated by one or more molecules included in the composition of a product.

[0031] The odor masking agent may be chosen from: a) monoesters; b) di- and / or triesters; c) alcohols, advantageously monoalcohols, comprising from 1 to 30 carbon atoms, said carbon atoms forming a linear or branched chain optionally comprising one or more unsaturations in the form of double bond(s), and optionally comprising a cyclic structure with 5 or 6 members, saturated, or totally or partially unsaturated;d) aldehydes and / or ketones, in particular aldehydes and / or ketones of formula R -CO-Rb, in which R represents a hydrocarbon chain comprising from 1 to 6 carbon atoms, linear or branched, optionally comprising one or more unsaturations in the form of double bond(s), and R represents a hydrogen atom, a cyclic hydrocarbon chain or a linear or branched hydrocarbon chain, optionally, but preferably, substituted by a cyclic structure, R comprising from 6 to 12 carbon atoms, optionally comprising one or more unsaturations in the form of double bond(s) and being optionally substituted by one or more hydroxyl groups; and e) terpenes.;

[0032] The term "insecticide" means an active substance or preparation having the property of killing insects and more particularly mosquitoes, or other invertebrates (mites, myriapods). The insecticide can be obtained by chemical synthesis or of plant origin. In the context of the present invention, the insecticide is of plant origin. It can be chosen from limonene, or geraniol.

[0033] The concentration of the volatile organic substance in the volatile solvent may range from 0.05% to 50% by weight, in particular from 1% to 45% by weight, in particular from 2% to 40% by weight, in particular from 3% to 35% by weight, in particular from 5% to 30% by weight, or in particular from 10% to 45% by weight, in particular from 15% to 40% by weight, in particular from 20% to 35% by weight relative to the total weight of part A.

[0034] The volatile solvent according to the invention may be chosen from a large number of solvents and may be one or a combination of several solvents. Preferably, the volatile solvent is odorless or very slightly odorous. In all cases, the volatile solvent must be capable of solubilizing the dihydroxy PDMS.

[0035] In a first embodiment of the invention, the volatile solvent capable of solubilizing the dihydroxy PDMS is chosen from apolar solvents, such as C7 to C12 isoparaffins, silicone hexamethyl disiloxane, octamethyl trisiloxane, decamethyl tetrasiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, docamethyl cyclohexasiloxane, hexane. Commercial examples of volatile isoparaffins are ISOPAR C® to ISOPAR P® from the company EXXON CHEMICAL, with Flash Point, from 40 to 100°C. Preferably, the volatile solvent is C10-12 isoparaffin.

[0036] In a second embodiment of the invention, the volatile solvent capable of solubilizing the dihydroxy PDMS is chosen from low molecular weight alkanes and low polar solvents, such as fatty acid esters such as isopropyl myristate, butyl myristate, isobutyl oleate, isopropyl oleate, and diisopropyl adipate.

[0037] Furthermore, Part A of the system comprises from 0.01% to 5% by weight of a carboxylic acid, in particular 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.21%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.50%, 1%, 1, 50%, 2%, 2.50%, 3%, 3.50%, 4%, 4.50% or 5%.

[0038] Carboxylic acid allows you to control the curing time of the silicone elastomer by adjusting the amount of carboxylic acid used. The more acid is used, the better the cure time. The higher the curing time, the shorter the curing time. The carboxylic acid thus helps to accelerate the curing time of the silicone elastomer.

[0039] The carboxylic acid is chosen in particular from the carboxylic acids of the following formula (I): Q HAS. R" OH (i) in which R represents hydrogen, a linear or branched C1-C17 alkyl, a linear or branched C5-C17 alkenyl, in particular a branched C4-C5 alkenyl, or a phenyl group.

[0040] The carboxylic acid may be selected from stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, undecylenic acid, capric acid, methyl-2-pentenoic acid, acetic acid, formic acid, isovaleric acid, methyl-2-butyric acid, or phenylacetic acid.

[0041] In a preferred embodiment, the carboxylic acid is myristic acid.

[0042] In a preferred embodiment, the carboxylic acid is present between 0.02% and 1% by weight based on the weight of Part A. In an even more preferred embodiment, the carboxylic acid is present between 0.05% and 0.5% by weight based on the weight of Part A.

[0043] Part B

[0044] Part B of the system comprises 10% to 30% N-Morpholinomethyltriethoxysilane (MMT). This compound acts as a crosslinking agent within the system. This crosslinking agent is diluted in a solvent consisting of a non-functionalized PDMS silicone oil with a viscosity between 10 and 245 cSt (mm 2 / s) (measured at 25 °C) capable of solubilizing said MMT. The viscosity of the non-functionalized PDMS silicone oil, which is expressed as kinematic viscosity in cSt (mm2 / sec), is measured as dynamic viscosity (Pa-sec units) at 25 °C using a TA Instruments Discovery HR-2 rheometer and the standard method provided by DIN 53019 (2008) (including their calibration), and then converted from dynamic viscosity to kinematic viscosity by dividing the former by the density of the non-functionalized PDMS silicone oil. The solvent is, in turn, present in an amount between 70% and 90% of Part B.

[0045] Preferably, the non-functionalized PDMS silicone oil has a viscosity measured at 25°C of 10 cSt (mm 2 / s).

[0046] The Applicant has found that there is an advantageous molar ratio between the amount of carboxylic acid and the amount of MMT used in the process of the present invention. This advantageous molar ratio between the amount of carboxylic acid and the amount of MMT is between 0.1 and 1. In a particular embodiment of the invention, the ratio between the amount of carboxylic acid and the amount of MMT is between 0.1 and 1. A ratio greater than 0.1 makes it possible to obtain good crosslinking times, i.e. less than 2 hours, without using too much carboxylic acid. When the ratio is above 1, the addition of carboxylic acid has less effect on the crosslinking time.

[0047] A second subject relates to a silicone gel capable of being obtained by the process which is the subject of the present invention, characterized in that it does not comprise a metal catalyst.

[0048] The gel according to the invention is characterized in that it allows diffusion, that is to say a controlled release in time and space of the volatile organic substance. Thus, the gel can be used to perfume or deodorize the atmosphere, the laundry, or as an insect repellent or insecticide. Preferably the gel is used to perfume the atmosphere. When used as a perfuming or deodorizing product, the silicone gel can be used in any type of environment, in particular in premises for domestic, commercial or industrial use or in a car.

[0049] The silicone gel according to the present invention is characterized in that it has the advantage of being transparent.

[0050] By transparent is meant a gel having a gel turbidity of less than 40 NTU (nephelometric turbidity units) at 25°C, measured using a turbidimeter. By "transparent" according to the present invention is not meant "colorless". Thus, a transparent gel can be a transparent and colored gel.

[0051] In a preferred embodiment of the invention, the turbidity of the gel is less than 20 NTU, more preferably less than 12 NTU, most preferably less than 8 NTU. NTU (nephelometric turbidity units) is the unit used to describe turbidity. The greater the scattering, the higher the turbidity. Therefore, low NTU values ​​indicate high clarity, while high NTU values ​​indicate low clarity. The measurement method of a turbidimeter is based on a comparison of the intensity of light scattered by the sample under defined conditions with the intensity of light scattered by a standard reference suspension, which is normally water without turbidity (distilled water or distilled water passed through a 0.45 µm membrane filter). The turbidimeter will consist of a nephelometer with a light source to illuminate the sample and one or more detectors photoelectric with a readout device to indicate the intensity of scattered light at right angles to the incident light path. The turbidimeter should be designed so that little stray light reaches the detector in the absence of turbidity and should be free from significant drift after a short warm-up period.

[0052] The Hach Model 2100 and 2100 A turbidimeter is widely used and has proven reliable; however, other instruments meeting the above design criteria are acceptable, for example, the T u rbi-di rect® marketed by Aqua lytique.

[0053] Advantageously, the silicone gel according to the invention does not comprise a reinforcing agent.

[0054] Advantageously, the silicone gel according to the invention has a relative resistance of less than 20 g / mm.

[0055] Furthermore, the gel according to the invention is anhydrous. Anhydrous means "water-free", i.e. a gel in which no water is present in the form of hydrate or water of crystallization.

[0056] A third subject of the present invention relates to the use of a carboxylic acid in a process for preparing a silicone gel diffusing volatile organic substance from a two-component cold-vulcanizable silicone elastomer to control the crosslinking time of said elastomer.

[0057] Not only does the carboxylic acid allow the crosslinking time to be controlled, but more specifically it allows the crosslinking time of said elastomer to be accelerated in a controlled manner.

[0058] The carboxylic acid usable in the present invention is of general formula (I) as follows in which R represents hydrogen, a linear or branched C1-C17 alkyl, a linear or branched C5-C17 alkenyl, in particular a branched C4-C5 alkenyl, or a phenyl group.

[0059] In a preferred embodiment, the carboxylic acid used is chosen from stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, undecylenic acid, capric acid, methyl-2-pentenoic acid, acetic acid, formic acid, isovaleric acid, 2-methylbutyric acid, phenylacetic acid. Preferably, the carboxylic acid is myristic acid.

[0060] A fourth object of the present invention relates to a kit for implementing the method according to the present invention, characterized in that it comprises: - a part A comprising (i) from 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity measured at 25°C between 3000 and 100000 cSt (mm 2 / s) and (ii) from 10% to 90% by weight of a mixture including at least one volatile solvent capable of solubilizing the dihydroxy PDMS polymer and a volatile organic substance; - a part B comprising (iii) from 10% to 30% by weight of MMT and (iv) from 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity measured at 25°C between 10 and 245 cSt (mm 2 / s) capable of solubilizing MMT; characterized in that part A also comprises from 0.01% to 5% by weight of a carboxylic acid and does not comprise a metal catalyst and in that part A and part B are physically separated from each other.

[0061] In the kit, parts A and B are as defined previously.

[0062] The invention is illustrated below by the following examples, which should not be considered as limiting the scope of the invention, and should be read with reference to the figures. Examples

[0063] Example 1: Composition of Part A (Silicone Matrix): Dihydroxy PDMS (polymer purchased from WACKER®, trade name FD6 6000cSt (mm 2 / s)) =60g (60% by weight) Perfume = 30g (30% by weight) Isopar L (Exxon) = 4.6g (4.6% by weight) Isopar M (Exxon) = 5g (5% by weight) Myristic Acid (MA) = 0.4g (0.4% by weight) The preferred percentage of myristic acid is 0.4% by weight, but this amount can change depending on the fragrance used and the desired crosslinking time.

[0064] Example 2: Composition of Part B (crosslinking agent): Silicone oil 10cSt (mm 2 / s) = 85% by weight MMT ((N-Morpholinomethyl) triethoxysilane) CAS# 21743-27-1 =15% by weight This crosslinking agent solution is purchased from WACKER® under the name HC1015 and is used as such.

[0065] Example 3: Scented silicone gel Part A according to Example 1 = 97% by weight Part B according to Example 2 = 3% by weight Add Part B (crosslinking agent) to Part A and mix until smooth. Pour the mixture into a glass or PET container, close, and allow the gel to form.

[0066] Example 4: Action of different acids To highlight the similar effect of different carboxylic acids, several silicone gels were prepared with the same molar amount of acid. The gels were prepared according to the formula and method indicated in Example 3. To prepare these gels, the perfume described in Example 1 was replaced by an equivalent amount of Isopar L. Approximately 1 g of this mixture is then loaded into the rheometer to measure the crosslinking time.

[0067] Procedure for measuring crosslinking time The curing time is measured using a TA-Instruments Discovery HR-2 rheometer. The measurement is made in Oscillation-Time mode and the curing time is taken at the intersection of the elastic modulus and the losses G' and G”.

[0068] The rheometer measurement protocol is described below: Geometry: 40.0mm 3.9875° flat cone Mode: Oscillation-Time Temperature: 25°C Sampling interval: 30.0 s / pt Constraint: 1% Frequency: 1 Hz Gap: 110 pm

[0069] This example highlights that various carboxylic acids of different chain lengths can be used to reduce crosslinking time. Furthermore, it is found that the chain length of the carboxylic acid used has no influence on the crosslinking time.

[0070] Example 5: Control of crosslinking time

[0071] To demonstrate the possibility of controlling the crosslinking time by adding a very small amount of carboxylic acid, several gels were prepared with different amounts of myristic acid. The gels were prepared according to the formula and method given in Example 3. To prepare these gels, the perfume described in Example 1 was replaced by an equivalent amount of Isopar L. Approximately 1g of this mixture is then loaded into the rheometer to perform the crosslinking time measurement as described previously.

[0072] To highlight the possibility of controlling the crosslinking time by adding a very small amount of myristic acid.

[0073] Table 2: Effect of the percentage of myristic acid on crosslinking time 0074] As shown in Table 2 and Figure 1, the addition of a very small amount of myristic acid reduces the crosslinking time of the silicone matrix + crosslinking agent mixture (Part A + Part B). The higher the amount of acid, the shorter the crosslinking time. The user can thus control the crosslinking time by adjusting the amount of acid (here myristic) added.

[0075] Figure 2 represents the molar ratio (r) = n acid / n MMT. The graph shown in Figure 2 is useful when one wishes to know how much of a given carboxylic acid should be used to obtain the desired crosslinking time.

[0076] Example 6: Crosslinking time of perfumed formulations

[0077] To highlight the fact that the crosslinking time can be controlled when using different perfume compositions, several gels were made according to the formula given in Example 3.

[0078] Table 3: Crosslinking time obtained when producing silicone gels made with different perfume compositions

[0079] As this table shows, the addition of carboxylic acid significantly reduces the crosslinking time of the scented gels described in Table 3.

Claims

Claims

1. A method of preparing a silicone gel for diffusing volatile organic substance, said method comprising the following steps: 1) Provision of a Part A comprising (i) from 10% to 89.99% by weight of a dihydroxy polydimethylsiloxane polymer having a viscosity measured at 25°C between 3000 and 100000 mm 2 / s and (ii) from 10% to 90% by weight of a mixture including: - a volatile solvent which is capable of solubilizing the dihydroxy polydimethylsiloxane polymer and - a volatile organic substance; 2) Provision of a Part B comprising (iii) from 10% to 30% by weight of N- Morpholinomethyl triethoxysilane and (iv) from 70% to 90% by weight of a non-functionalized polydimethylsiloxane silicone oil having a viscosity measured at 25°C between 10 and 245 mm 2 / s capable of solubilizing N-Morpholinomethyl triethoxysilane; 3) Preparation of a mixture comprising from 95% to 99% by weight of part A and from 1% to 5% by weight of part B; characterized in that part A also comprises from 0.01% to 5% by weight of a carboxylic acid and does not comprise a metal catalyst.

2. Process according to claim 1, characterized in that the carboxylic acid is of the following general formula (I): in which R represents hydrogen, a linear or branched C1-C17 alkyl, a linear or branched C5-C17 alkenyl, in particular a branched C4-C5 alkenyl, or a phenyl group.

3. Process according to claim 1 or 2, characterized in that the carboxylic acid is chosen from stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, undecylenic acid, capric acid, methyl-2-pentenoic acid, acetic acid, formic acid, isovaleric acid, methyl-2-butyric acid or phenylacetic acid.

4. Process according to any one of claims 1 to 3, characterized in that the carboxylic acid is myristic acid.

5. A process according to any one of claims 1 to 4, characterized in that the carboxylic acid is present between 0.02% and 1% by weight relative to the total weight of part A.

6. Method according to any one of claims 1 to 5, characterized in that the dihydroxy polydimethylsiloxane has a viscosity measured at 25°C between 4000 and 8000 mm 2 / s.

7. Method according to any one of claims 1 to 6, characterized in that the volatile organic substance is chosen from a perfume, an odor masking agent or an insecticide.

8. A method according to any one of claims 1 to 7, characterized in that the concentration of the volatile organic substance in the volatile solvent is from 0.05% to 50% by weight, in particular from 5% to 30% by weight relative to the total weight of part A.

9. Process according to any one of claims 1 to 8, characterized in that the volatile solvent capable of solubilizing the dihydroxy polydimethylsiloxane is chosen from apolar solvents, such as C7 to C12 isoparaffins, silicone hexamethyl disiloxane, octamethyl trisiloxane, decamethyl tetrasiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, docamethyl cyclohexasiloxane, hexane.

10. Process according to any one of claims 1 to 8, characterized in that the volatile solvent capable of solubilizing the dihydroxy polydimethylsiloxane is chosen from low molecular weight alkanes and low polar solvents, such as fatty acid esters such as isopropyl myristate, butyl myristate, isobutyl oleate, isopropyl oleate, and diisopropyl adipate.

11. A method according to claim 9, characterized in that the volatile solvent is C10-C12 isoparaffin.

12. Process according to any one of claims 1 to 11, characterized in that the molar ratio between the quantity of carboxylic acid and the quantity of N- Morpholinomethyl triethoxysilane is between 0.1 and 1.

13. Silicone gel diffusing volatile organic substance capable of being obtained by the process according to any one of claims 1 to 12, characterized in that it does not comprise a metal catalyst.

14. Silicone gel for diffusing volatile organic substance according to claim 13, characterized in that it is transparent.

15. Silicone gel for diffusing volatile organic substance according to claims 13 or 14, characterized in that it does not comprise a reinforcing agent.

16. Silicone gel for diffusing volatile organic substance according to any one of claims 13 to 15, characterized in that it has a relative resistance of less than 20 g / mm.

17. Use of a carboxylic acid in a process for preparing a silicone gel diffusing volatile organic substance from a two-component cold-vulcanizable silicone elastomer to control the crosslinking time of said elastomer.

18. Use according to claim 17, for accelerating in a controlled manner the crosslinking time of said elastomer.

19. Use according to claims 17 or 18 characterized in that the carboxylic acid is of the following general formula (I): in which R represents hydrogen, linear or branched C1-C17 alkyl, linear or branched C5-C17 alkenyl, in particular branched C4-C5 alkenyl, or a phenyl group.

20. Use according to any one of claims 17 to 19, characterized in that the carboxylic acid is chosen from stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, undecylenic acid, capric acid, methyl-2-pentenoic acid, acetic acid, formic acid, isovaleric acid, methyl-2-butyric acid or phenylacetic acid.

21. Use according to any one of claims 17 to 20, characterized in that the carboxylic acid is myristic acid.

22. Kit for implementing the method according to any one of claims 1 to 12, said kit comprising: - a part A comprising (i) from 10% to 89.99% by weight of a dihydroxy polydimethylsiloxane polymer having a viscosity measured at 25°C between 3000 and 100000 mm 2 / s and (ii) from 10% to 90% by weight of a mixture including at least one volatile solvent capable of solubilizing the dihydroxy polydimethylsiloxane polymer and a volatile organic substance; - a part B comprising (iii) from 10% to 30% by weight of N-Morpholinomethyl triethoxysilane and (iv) from 70% to 90% by weight of a polydimethylsiloxane silicone oil non-functionalized having a viscosity measured at 25°C between 10 and 245 mm 2 / s capable of solubilizing N-Morpholinomethyl triethoxysilane; characterized in that part A also comprises from 0.01% to 5% by weight of a carboxylic acid and does not comprise a metal catalyst and in that part A and part B are physically separated from each other.

Images