Method for controlling the crosslinking time of polysiloxane gel releasing

Abstract

The present invention relates to a method for preparing a volatile organic substance-releasing polysiloxane gel, said method comprising the steps of: 1) providing a part A comprising (i) 10 to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity measured at 25 DEG C of from 3000 to 100000 mm2 / s, and (ii) from 10% to 90% by weight of a mixture comprising a volatile solvent capable of dissolving the dihydroxypolydimethylsiloxane 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 polydimethylsiloxane silicone oil having a viscosity of from 10 to 245 cSt (mm2 / s), measured at 25 DEG C, capable of solubilizing N-morpholine methyltriethoxysilane, and (iv) from 70% to 90% by weight of a non-functionalized polydimethylsiloxane silicone oil having a viscosity of from 10 to 245 cSt (mm2 / s), measured at 25 DEG C, capable of solubilizing N-morpholine methyltriethoxysilane; 3) preparing a mixture comprising 95% to 99% by weight of a Part A and 1% to 5% by weight of a Part B; characterised in that Part A further comprises 0.01% to 5% by weight of a carboxylic acid and does not comprise any metal catalyst, as well as gels obtainable by this method and kits for carrying out this method.

Description

Field of the Invention

[0001] The present invention relates to the field of articles for perfuming or deodorizing air or laundry, or as insect repellents or insecticides, said articles comprising a solid polymeric material containing volatile organic substances. More particularly, the present invention relates to transparent anhydrous polysiloxane gels which diffuse volatile organic substances, said gels not containing reinforcing agents or toxic catalysts and having the advantage that the crosslinking time is easily controllable. Background Art

[0002] Currently, there are various devices for releasing and / or diffusing volatile organic substances (such as fragrances, odor-absorbing molecules or insecticides) into the environment. These devices can be in various forms suitable for their uses and can be obtained in various ways. Generally, these products are composed of organic matrices (especially polymers) of siloxane type.

[0003] Currently, there are various techniques for producing such organic polymer matrices, especially matrices obtained from polysiloxane elastomers, in which one or more volatile organic substances are dispersed.

[0004] A preferred polysiloxane elastomer is a cold vulcanized polysiloxane elastomer (CVE), which is formulated from reactive polydimethylsiloxanes (PDMS) with different degrees of polymerization. Crosslinking is achieved at room temperature by a crosslinking agent and a catalyst, which reacts with the reactive groups in the polysiloxane chains, and the catalyst allows control of the crosslinking. The elastomer can be single-component (EVF1) or two-component (EVF2, also known as "room temperature vulcanization" RTV), where one or both parts contain a catalyst. When the product is single-component, the polymerization reaction is activated by contact of the product with atmospheric humidity. When the product is two-component, the crosslinking is not activated by atmospheric humidity. It starts when the two components are mixed.

[0005] Japanese Patent 82-40 558 describes a method for manufacturing a polysiloxane elastomer matrix for diffusing fragrances into the air. A siloxane elastomer composition is mixed with a fragrance, and then the crosslinking of the composition is triggered in a mold by adding an organometallic salt. Due to the incompatibility of the polymer and the fragrance composition, the resulting matrix has non-linear fragrance diffusion characteristics.

[0006] European Patent EP 2 247 318 describes transparent anhydrous gels in the form of crosslinked polysiloxane networks, containing volatile substances (especially fragrances) and non-volatile substances, and not containing any fillers or reinforcing agents. The crosslinking of the polysiloxane gel is achieved by the presence of metal-based catalysts (such as tin, titanium or platinum).

[0007] However, many of these devices have significant drawbacks. For example, the use of catalysts, especially metal catalysts, makes these devices potentially harmful to the environment due to their toxicity. Other devices require fillers or reinforcing agents, which have the disadvantage of making the gel opaque or increasing its hardness. Some devices become opaque once formed, which makes them less attractive to consumers who desire transparent products. For other types of devices, the problem will be related to the amount of volatile organic substances, which is limited and thus less effective in terms of space and time.

[0008] The biggest problem faced by manufacturers is that the polysiloxane-based RTV polymer matrix obtained by mixing two different parts requires a very long cross-linking time, which is difficult to manage on an industrial scale when very little cross-linking agent is added. Nowadays, manufacturers need a technology that enables them to control the cross-linking time of the polymer matrix at will, especially to accelerate the cross-linking time, while using a very small amount of cross-linking agent (which is necessary to obtain an opaque gel that does not emit an unpleasant fishy smell). Summary of the Invention

[0009] The present disclosure is an improvement based on the above situation and solves several technical problems at the same time.

[0010] Specifically, the applicant has found that adding a very small amount of carboxylic acid to a two-part system for manufacturing an organic polymer matrix (also known as a polysiloxane gel) can control the cross-linking time of the system.

[0011] Therefore, the present invention relates to a method for preparing a polysiloxane gel for diffusing volatile organic substances, which is prepared using a two-component cold-curing polysiloxane elastomer without a metal catalyst and whose cross-linking time can be controlled.

[0012] More precisely, the first subject of the present invention relates to a method for preparing a polysiloxane gel for diffusing volatile organic substances, the method comprising the following steps:

[0013] 1) Providing part A, which contains (i) 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity of 3000 to 100,000 cSt (mm 2 / s) measured at 25 °C, and (ii) 10% to 90% by weight of a mixture containing a volatile solvent and volatile organic substances capable of dissolving the dihydroxy PDMS polymer;

[0014] 2) Providing part B, which contains (iii) 10% to 30% by weight of MMT, and (iv) 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity of 10 to 245 cSt (mm2 / s) measured at 25 °C and capable of dissolving MMT;

[0015] 3) Prepare a mixture comprising 95% to 99% by weight of part A and 1% to 5% by weight of part B;

[0016] Characterized in that part A further comprises 0.01% to 5% by weight of carboxylic acid and does not contain any metal catalyst.

[0017] The second subject of the present invention relates to a polysiloxane gel obtainable by the method according to the present invention, characterized in that it does not contain any metal catalyst.

[0018] The third subject of the present invention relates to the use of carboxylic acid in a method for preparing a polysiloxane gel for diffusing volatile organic substances from a two-component cold-curing polysiloxane elastomer to control the crosslinking time of the elastomer.

[0019] The fourth subject of the present invention relates to a kit for carrying out the method according to the present invention, characterized in that the kit comprises:

[0020] - Part A, which comprises (i) 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity of 3000 to 100000 cSt (mm2 / s) measured at 25°C, and (ii) 10% to 90% by weight of a mixture comprising at least one volatile solvent and volatile organic substances capable of dissolving the dihydroxy PDMS polymer;

[0021] - Part B, which comprises (iii) 10% to 30% by weight of MMT, and (iv) 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity of 10 to 245 cSt (mm2 / s) measured at 25°C and capable of dissolving MMT;

[0022] Characterized in that part A further comprises 0.01% to 5% by weight of carboxylic acid and does not contain any metal catalyst, and part A and part B are physically separated from each other. Description of the Drawings

[0023] Other features, details and advantages will become apparent upon reading the following detailed description and analyzing the drawings, wherein:

[0024] Figure 1

[0025] Figure 1 shows the effect of adding myristic acid on the crosslinking time.

[0026] Figure 2

[0027] Figure 2 shows the molar ratio of carboxylic acid / N-morpholinomethyltriethoxysilane (MMT).​​ DETAILED DESCRIPTION OF THE INVENTION

[0029] The polysiloxane gel for diffusing volatile organic substances according to the present invention is obtained from a two-component system (RTV) that can be crosslinked at room temperature. Such a system is typically packaged in two different and physically separated parts, namely, a part containing a crosslinkable polysiloxane elastomer (Part A) and a crosslinking part (Part B). The polysiloxane gel is prepared by mixing the two parts together and then allowing the gel to form, for example, in a mold. The crosslinkable silicone composition according to the present invention is a functionalized silicone polymer.

[0030] According to the present invention, the polysiloxane gel for diffusing volatile organic substances is prepared in the following manner:

[0031] 1) Provide Part A, which contains (i) 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity of 3000 to 100,000 cSt (mm2 / s) measured at 25°C, and (ii) 10% to 90% by weight of a mixture containing a volatile solvent and a volatile organic substance capable of dissolving the dihydroxy PDMS polymer;

[0032] 2) Provide Part B, which contains (iii) 10% to 30% by weight of MMT, and (iv) 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity of 10 to 245 cSt (mm2 / s) measured at 25°C and capable of dissolving MMT;

[0033] 3) Prepare a mixture containing 95% to 99% by weight of Part A and 1% to 5% by weight of Part B;

[0034] Part A further contains 0.01% to 5% by weight of carboxylic acid and does not contain any metal catalyst.

[0035] The term "gel" means a homogeneous, elastic, network-forming composition having a relative resistance of less than 20 g / mm, particularly less than 15 g / mm, preferably less than 10 g / mm. The relative resistance of the gel is measured at 25°C using a texture analyzer.

[0036] For example, the "compression force measurement" mode of the TA-XT texture analyzer from Rheo company can be used, with a 6 mm Stable Micro Systems SMS P / 6 stainless steel cylindrical probe; test speed 0.50 mm / sec; target mode: distance; break mode: rate; break sensitivity 5.0 g.

[0037] Part A

[0038] Part A contains 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity of 3000 to 100,000 cSt (mm2 / s) measured at 25°C. In the context of the present invention, the functionalized siloxane polymer is a functionalized polydimethylsiloxane with hydroxyl groups at both ends (also known as dihydroxy PDMS), which has a viscosity of 3000 to 100,000 cSt (mm2 / s). Its viscosity measured at 25°C can be 3000 to 75,000 cSt (mm2 / s), 3000 to 50,000 cSt (mm 2 / s), 3000 to 35,000 cSt (mm 2 / s), 3000 to 10,000 cSt (mm 2 / s), 3000 to 9000 cSt (mm 2 / s), 4000 to 8000 cSt (mm2 / s), 5000 to 7000 cSt (mm2 / s). Preferably, the dihydroxy PDMS polymer has a viscosity of about 6000 cSt (mm2 / s) measured at 25°C. The viscosity of the dihydroxy PDMS polymer is expressed in terms of dynamic viscosity cSt (mm2 / sec), and the dynamic viscosity (in Pa-sec units) is measured at 25°C using a TA Instruments Discovery HR-2 rheometer according to the standard method provided by DIN 53019 (2008) (including its calibration), and then the dynamic viscosity is converted to kinematic viscosity by dividing the former by the density of the dihydroxy PDMS polymer.

[0039] The advantage of the present invention over the existing systems is that the system does not require the addition of metal catalysts, especially tin catalysts, for crosslinking.

[0040] Part A also contains 10% to 90% by weight of a mixture containing a volatile solvent and volatile organic substances capable of dissolving the dihydroxy PDMS polymer.

[0041] The term "volatile organic substances" means products containing one or more organic molecules, the vapor pressure of which is higher than atmospheric pressure at room temperature (i.e., 25°C). The volatile organic substances used according to the present invention can be selected from fragrances, odor masking agents, or insecticides. Preferably, it is a fragrance.

[0042] The fragrance can be selected from a large number of aromatic compounds. The fragrance according to the present invention can be a combination of one or more aromatic compounds. For example, such aromatic compounds as those mentioned in S. Arctander, "Perfume and Flavors" (Montclair, N.J., 1969) or "Common Fragrance and Flavor Materials", Wiley-VCH, Weinheim, 2006.

[0043] The latter are non-limiting examples of compounds belonging to the following classes:

[0044] - Aromatic hydrocarbons, terpenes and / or sesquiterpenes, especially essential oils containing these molecules, especially essential oils of citrus fruits (lemon, orange, grapefruit, bergamot), nutmeg essential oil, etc.,

[0045] - Aromatic alcohols, especially benzyl alcohol, phenethyl alcohol and phenylpropyl alcohol,

[0046] - Alcohols, especially cyclic or acyclic, saturated or unsaturated, primary, secondary or tertiary non-aromatic linalool, citronellol, geraniol, nerol, dihydromyrcenol, terpineol and alicyclic alcohols with a carbon chain containing 4 to 10 carbon atoms,

[0047] - Aldehydes, especially saturated and unsaturated alicyclic aliphatic aldehydes with a carbon chain containing 4 to 12 carbon atoms, aromatic aldehydes (such as cinnamaldehyde, α-amylcinnamaldehyde and α-hexylcinnamaldehyde aromatic aldehydes), lily aldehyde and phenolic aldehydes (such as vanillin and ethyl vanillin),

[0048] - Phenols, especially aromatic phenols, such as eugenol and isoeugenol, and related methyl ethers,

[0049] - Carboxylic acid esters, especially acetate esters of benzyl alcohol, geraniol, citronellol, nerol, terpineol, borneol or linalool,

[0050] - Aromatic acid esters, such as benzoate esters and salicylate esters, and cinnamate esters esterified with alcohols from the series of aliphatic alcohols containing 1 to 6 carbon atoms,

[0051] - Aromatic phenolic acids, mainly in their aromatic lactone forms, such as coumarin and dihydrocoumarin,

[0052] - Alcohol carboxylic acids, in their lactone forms, and dodecalactones, especially octalactones, undecalactones and γ-dodecalactones, δ-decalactones, δ-undecalactones and δ-lactones in saturated or unsaturated forms, [[ID=...]]

[0053] - Macrocyclic compounds with a carbon chain containing 12 to 16 carbon atoms,

[0054] - acyclic or cyclic ethers and acetals, especially aromatic and non-aromatic aldehyde acetals with a carbon chain containing 4 to 10 carbon atoms, and substituted furan ring ethers and substituted or unsubstituted pyran ring ethers,

[0055] - heterocyclic compounds containing one nitrogen atom, especially indole derivatives, and heterocyclic compounds containing two nitrogen atoms, especially compounds of the pyrazine series,

[0056] - ketones, especially aromatic ketones such as 4-(p-hydroxyphenyl)-2-butanone and cyclic or acyclic, saturated or unsaturated non-aromatic ketones, especially those of the pyrazine series,

[0057] - aromatic or non-aromatic sulfides, disulfides and thiols.

[0058] The term "odor masking agent" or "odor neutralizer" means a reagent capable of reducing or eliminating the perception of an unpleasant odor generated by one or more molecules in the composition of a product.

[0059] The odor masking agent can be selected from the following: a) monoesters; b) diesters and / or triesters; c) alcohols, advantageously monoalcohols containing 1 to 30 carbon atoms, the carbon atoms forming a straight-chain or branched structure, optionally containing one or more unsaturated bonds in the form of double bonds, and optionally containing a saturated or partially or fully unsaturated 5- or 6-membered ring structure; d) aldehydes and / or ketones, especially aldehydes and / or ketones having the structural formula R-CO-Rb, where R represents a straight-chain or branched hydrocarbon chain containing 1 to 6 carbon atoms, optionally containing one or more unsaturated bonds in the form of double bonds, and Rb represents a hydrogen atom, a cycloalkyl chain or a straight-chain or branched hydrocarbon chain, optionally but preferably substituted by a cyclic structure, R contains 6 to 12 carbon atoms, optionally containing one or more unsaturated bonds in the form of double bonds, and optionally substituted by one or more hydroxyl groups; e) terpenes.

[0060] The term "pesticide" means an active substance or preparation having the property of killing insects (especially mosquitoes) or other invertebrates (mites, centipedes). Pesticides can be obtained by chemical synthesis or from plants. In the context of the present invention, the pesticide is derived from plants. It can be limonene or geraniol.

[0061] Relative to the total weight of Part A, the concentration of volatile organic substances in the volatile solvent can be 0.05% to 50% by weight, especially 1% to 45%, especially 2% to 40%, especially 3% to 35%, especially 5% to 30%, especially 10% to 45%, especially 15% to 40%, especially 20% to 35%.

[0062] The volatile solvent according to the present invention can be selected from a large number of solvents and can be a combination of one or several solvents. Preferably, the volatile solvent is odorless or has only a very slight odor. In all cases, the volatile solvent must be able to dissolve dihydroxy PDMS.

[0063] In a first embodiment of the present invention, the volatile solvents capable of dissolving dihydroxy PDMS are selected from non-polar solvents such as C7-C12 isoparaffins, polysiloxanes hexamethyldisiloxane, octamethytrisiloxane, decamethyldisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and hexane. Commercial examples of volatile isoparaffins are Isopar from Exxon Chemical Company to Isopar with a flash point of 40 to 100 °C. Preferably, the volatile solvent is C10-12 isoparaffin.

[0064] In a second embodiment of the present invention, the volatile solvents capable of dissolving dihydroxy PDMS are selected from low molecular weight alkanes and weakly polar solvents such as fatty acid esters, such as isopropyl myristate, butyl myristate, isobutyl oleate, isopropyl oleate, and diisopropyl sebacate.

[0065] In addition, part A of the system contains 0.01% to 5% by weight, 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%, 0.23%, 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% of carboxylic acid.

[0066] The carboxylic acid can control the crosslinking time of the polysiloxane elastomer by adjusting the amount of carboxylic acid used. The higher the amount of acid, the shorter the crosslinking time. Therefore, the carboxylic acid can accelerate the crosslinking time of the polysiloxane elastomer.

[0067] The carboxylic acid is particularly selected from carboxylic acids of the following formula (I):

[0068]

[0069] Wherein R represents hydrogen, a linear or branched C1-C17 alkyl group, a linear or branched C5-C17 alkenyl group, especially a branched C4-C5 alkenyl group, or a phenyl group.

[0070] The carboxylic acid can 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.

[0071] In a preferred embodiment, the carboxylic acid is myristic acid.

[0072] In a preferred embodiment, the carboxylic acid is present in an amount of 0.02 wt% to 1 wt% relative to the weight of part A. In a more preferred embodiment, the carboxylic acid is present in an amount of 0.05 wt% to 0.5 wt% relative to the weight of part A.

[0073] Part B

[0074] Part B of the system comprises 10 wt% to 30 wt% of N-morpholinomethyltriethoxysilane (MMT). This compound acts as a crosslinking agent in the system. This crosslinking agent is diluted in a solvent composed of a non-functionalized PDMS silicone oil having a viscosity of 10 to 245 cSt (mm2 / s) (measured at 25 °C) and capable of dissolving the MMT. The viscosity of the non-functionalized PDMS silicone oil, expressed in terms of dynamic viscosity cSt (mm2 / sec), is measured at 25 °C using a TA Instruments Discovery HR-2 rheometer and according to the standard method provided by the DIN 53019 (2008) standard (including its calibration) for measuring dynamic viscosity in units of Pa-sec, and then the dynamic viscosity is converted to kinematic viscosity by dividing the former by the density of the non-functionalized PDMS silicone oil. The solvent, as part of it, is present in an amount of 70% to 90% of part B.

[0075] Preferably, the non-functionalized PDMS silicone oil has a viscosity of 10 cSt (mm 2 / s) measured at 25 °C.

[0076] The applicant has found that there is a favorable molar ratio between the amount of carboxylic acid and the amount of MMT used in the method of the present invention. This favorable molar ratio is 0.1 to 1. In a specific embodiment of the present invention, the ratio of the amount of carboxylic acid to the amount of MMT is 0.1 to 1. A ratio greater than 0.1 can shorten the crosslinking time to less than 2 hours without using an excessive amount of carboxylic acid. When the ratio exceeds 1, the addition of carboxylic acid has a smaller effect on the crosslinking time.

[0077] The second subject matter relates to a polysiloxane gel obtainable by the method according to the present invention, characterized in that it does not contain any metal catalyst.

[0078] The gel according to the invention is characterized in that it allows the diffusion of volatile organic substances, i.e., controlled release in time and space. Thus, the gel can be used for scenting or deodorizing air or clothing, or as an insect repellent or pesticide. Preferably, the gel is used for scenting air. When used as a fragrance or deodorant product, the polysiloxane gel can be used in any type of environment, especially in homes, commercial or industrial premises or cars.

[0079] The polysiloxane gel according to the invention is characterized in that it has the advantage of being transparent.

[0080] The term "transparent" means that the haze of the gel measured using a hazemeter at 25 °C is less than 40 NTU (nephelometric turbidity units). The term "transparent" according to the invention does not mean "colorless". Thus, a transparent gel can be a transparent and colored gel.

[0081] In a preferred embodiment, the haze of the gel is less than 20 NTU, more preferably less than 12 NTU, and most preferably less than 8 NTU. NTU (nephelometric turbidity units) is the unit for describing haze. The greater the scattering, the higher the haze. Thus, a low NTU value indicates high transparency, while a high NTU value indicates low transparency. The measurement process of the hazemeter is based on comparing the intensity of the scattered light of the sample under specific conditions with the intensity of the scattered light of a standard reference suspension, which is usually haze-free water such as distilled water or distilled water filtered through a .45 μm membrane. The hazemeter consists of a nephelometer with a light source (for irradiating the sample) and one or more photodetectors with a reading device for indicating the intensity of the light scattered perpendicular to the incident light path. The hazemeter must be designed such that in the absence of haze, very little stray light reaches the detector and there is no significant drift after short-term heating.

[0082] Hach company's models 2100 and 2100A hazemeters are widely used and proven to be reliable; however, other instruments meeting the above design criteria are also acceptable, such as the Turbi- machine sold by Aqualytique company.

[0083] Advantageously, the polysiloxane gel according to the invention does not contain any reinforcing agents.

[0084] Advantageously, the polysiloxane gel according to the invention has a relative resistance of less than 20 g / mm.

[0085] Furthermore, the gel according to the invention is anhydrous. The term "anhydrous" means "water-free", i.e., there is no water present in the gel in the form of hydrates or water of crystallization.

[0086] The third subject of the present invention relates to the use of carboxylic acids in a method for preparing a polysiloxane gel that diffuses volatile organic substances from a two-component cold-vulcanizing polysiloxane elastomer to control the crosslinking time of the elastomer.

[0087] Carboxylic acids can not only control the crosslinking time, but in particular, can accelerate the crosslinking time of the elastomer in a controlled manner.

[0088] The carboxylic acids that can be used in the present invention have the following general formula (I):

[0089]

[0090] wherein R represents hydrogen, a linear or branched C1-C17 alkyl group, a linear or branched C5-C17 alkenyl group, especially a branched C4-C5 alkenyl group, or a phenyl group.

[0091] In a preferred embodiment, the carboxylic acids used are selected from stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, undecenoic acid, capric acid, methyl-2-pentenoic acid, acetic acid, formic acid, isovaleric acid, methyl-2-butyric acid, and phenylacetic acid. Preferably, the carboxylic acid is myristic acid.

[0092] The fourth subject of the present invention relates to a kit for carrying out the method according to the present invention, characterized in that it comprises:

[0093] - Part A, which contains (i) 10% to 89.99% by weight of a dihydroxy PDMS polymer having a viscosity of 3000 to 100000 cSt (mm 2 / s) measured at 25 °C, and (ii) 10% to 90% by weight of a mixture comprising at least one volatile solvent and volatile organic substances capable of dissolving the dihydroxy PDMS polymer;

[0094] - Part B, which contains (iii) 10% to 30% by weight of MMT, and (iv) 70% to 90% by weight of a non-functionalized PDMS silicone oil having a viscosity of 10 to 245 cSt (mm2 / s) measured at 25 °C and capable of dissolving MMT;

[0095] Characterized in that Part A further contains 0.01% to 5% by weight of a carboxylic acid and does not contain any metal catalyst, and Part A and Part B are physically separated from each other.

[0096] In the kit, Part A and B are as defined above.

[0097] The present invention is illustrated by the following examples, which should not be considered as limiting the scope of the present invention and should be read with reference to the accompanying drawings. Examples

[0098] Example 1: Composition of Part A (Silicone Matrix):

[0099] Dihydroxy PDMS (polymer purchased from The product name is FD6 6000cSt(mm 2 / s))=60g (60% by weight)

[0100] Fragrance = 30 g (30% by weight)

[0101] Isopar L (Exxon) = 4.6 g (4.6% by weight)

[0102] Isopar M (Exxon) = 5 g (5% by weight)

[0103] Myristic acid (MA) = 0.4 g (0.4% by weight)

[0104] The preferred percentage of myristic acid is 0.4% by weight, but this amount can be adjusted depending on the flavor used and the desired crosslinking time.

[0105] Example 2: Composition of Part B (crosslinking agent):

[0106] Silicone oil 10cSt(mm 2 / s) = 85% by weight

[0107] MMT ((N-morpholinomethyl)triethoxysilane) CAS# 21743-27-1 = 15% by weight

[0108] This crosslinker solution was purchased from The trade name is HC1015 and it was used directly.

[0109] Example 3: Perfumed silicone gel

[0110] Part A according to Example 1 = 97% by weight

[0111] Part B according to Example 2 = 3% by weight

[0112] Add Part B (crosslinker) to Part A and mix until a homogeneous mixture is obtained. Pour the mixture into a glass or PET container, seal and allow to gel.

[0113] Example 4: Effects of various acids

[0114] To demonstrate similar effects of different carboxylic acids, several polysiloxane gels were prepared using the same molar amounts of acids.

[0115] Gels were prepared according to the formula and method given in Example 3. To prepare these gels, the fragrance described in Example 1 was replaced by an equal amount of Isopar L.

[0116] Then, about 1 g of this mixture was placed in a rheometer for crosslinking time measurement.

[0117] Crosslinking time measurement procedure

[0118] The crosslinking time was measured using a TA-Instruments Discovery HR-2 rheometer. The measurement was carried out in oscillatory-time mode, and the crosslinking time was taken at the intersection of the elastic modulus G' and the loss modulus G".

[0119] The rheometer measurement protocol was as follows:

[0120] - Geometry: 40.0 mm 3.9875° cone plate

[0121] - Mode: Oscillatory-time

[0122] - Temperature: 25 °C

[0123] - Sampling interval: 30.0 s / pt

[0124] - Stress: 1%

[0125] - Frequency: 1 Hz

[0126] - Gap: 110 μm

[0127]

[0128]

[0129] This example highlights the fact that various carboxylic acids with different chain lengths can be used to reduce the crosslinking time.

[0130] Furthermore, it was found that the chain length of the carboxylic acid used had no effect on the crosslinking time.

[0131] Example 5: Controlling the crosslinking time

[0132] To highlight 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.

[0133] These gels were prepared according to the formula and method given in Example 3. To prepare these gels, the fragrance described in Example 1 was replaced with an equal amount of Isopar L.

[0134] Then, about 1 g of this mixture was placed in a rheometer, and the crosslinking time was measured according to the method described previously.

[0135] To highlight the possibility of controlling the crosslinking time by adding a very small amount of myristic acid.

[0136] Table 2: Influence of myristic acid percentage on crosslinking time

[0137]

[0138] As shown in Table 2 and Figure 1 shown, adding a very small amount of myristic acid can reduce the crosslinking time of the polysiloxane matrix + crosslinker mixture (Part A + Part B). The greater the amount of acid, the shorter the crosslinking time. Therefore, the user can control the crosslinking time by adjusting the amount of acid added (in this case, myristic acid).

[0139] Figure 2 The molar ratio (r) = n acid / n MMT is represented. When it is necessary to know how much of a given carboxylic acid must be used to obtain the desired crosslinking time, Figure 2 the graph shown is advantageous.

[0140] Example 6: Crosslinking time of the perfumed formulation

[0141] To highlight the fact that the crosslinking time can be controlled when using different perfume formulations, several gels were prepared according to the formulation given in Example 3.

[0142] Table 3: Crosslinking times obtained when preparing polysiloxane gels with different perfume formulations.

[0143]

[0144] As shown in this table, adding carboxylic acid can significantly reduce the crosslinking time of the perfumed gels described in Table 3.

Claims

1. A method for preparing a polysiloxane gel for diffusing volatile organic substances, the method comprising the following steps: 1) Providing Part A, which contains (i) 10% to 89.99% by weight of a dihydroxypolydimethylsiloxane polymer having a viscosity of 3000 to 100000 mm2 / s measured at 25 °C, and (ii) 10% to 90% by weight of a mixture containing: - A volatile solvent capable of dissolving the dihydroxypolydimethylsiloxane polymer, and - A volatile organic substance; 2) Providing Part B, which contains (iii) 10% to 30% by weight of N-morpholinomethyltriethoxysilane, and (iv) 70% to 90% by weight of a non-functionalized polydimethylsiloxane silicone oil having a viscosity of 10 to 245 mm2 / s measured at 25 °C, which is capable of dissolving N-morpholinomethyltriethoxysilane; 3) Preparing a mixture containing 95% to 99% by weight of Part A and 1% to 5% by weight of Part B; Characterized in that Part A further contains 0.01% to 5% by weight of a carboxylic acid and does not contain any metal catalyst.

2. The method according to claim 1, wherein The carboxylic acid has the following general formula (I): wherein R represents hydrogen, a straight-chain or branched C1-C17 alkyl group, a straight-chain or branched C5-C17 alkenyl group, especially a branched C4-C5 alkenyl group, or a phenyl group.

3. The method according to claim 1 or 2, characterized in that, The carboxylic acid is selected from stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, undecenoic acid, capric acid, methyl-2-pentenoic acid, acetic acid, formic acid, isovaleric acid, methyl-2-butyric acid or phenylacetic acid.

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

5. The method according to any one of claims 1 to 4, characterized in that The carboxylic acid is present in an amount of 0.02% to 1% by weight relative to the total weight of Part A.

6. The method according to any one of claims 1 to 5, characterized in that The dihydroxypolydimethylsiloxane has a viscosity of 4000 to 8000 mm2 / s measured at 25 °C.

7. The method according to any one of claims 1 to 6, characterized in that, The volatile organic substance is selected from fragrances, odor masking agents or pesticides.

8. The 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 0.05% to 50% by weight, especially 5% to 30% by weight, relative to the total weight of Part A.

9. The method according to any one of claims 1 to 8, characterized in that, The volatile solvent capable of dissolving dihydroxypolydimethylsiloxane is selected from non-polar solvents such as C7-C12 isoparaffins, polysiloxane hexamethyldisiloxane, octamethytrisiloxane, decamethyldisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane and hexane.

10. The method according to any one of claims 1 to 8, characterized in that, The volatile solvent capable of dissolving dihydroxypolydimethylsiloxane is selected from low molecular weight alkanes and weakly polar solvents such as fatty acid esters, for example isopropyl myristate, butyl myristate, isobutyl oleate, isopropyl oleate and diisopropyl sebacate.

11. The method according to claim 9, wherein The volatile solvent is C10-C12 isoparaffin.

12. The method according to any one of claims 1 to 11, characterized in that, The molar ratio of the amount of the carboxylic acid to the amount of the N-morpholinomethyltriethoxysilane is 0.1 to 1.

13. A polysiloxane gel that diffuses volatile organic substances, which can be obtained by the method according to any one of claims 1 to 12, characterized in that, It does not contain any metal catalyst.

14. The polysiloxane gel for diffusing volatile organic substances according to claim 13, characterized in that, It is transparent.

15. The polysiloxane gel for diffusing volatile organic substances according to claim 13 or 14, characterized in that, It does not contain any reinforcing agent.

16. The polysiloxane gel for diffusing volatile organic substances 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 polysiloxane gel which diffuses volatile organic substances from a two-component cold-curing polysiloxane elastomer to control the crosslinking time of the elastomer.

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

19. The use according to claim 17 or 18, characterized in that, The carboxylic acid has the following general formula (I): wherein R represents hydrogen, a straight-chain or branched C1-C17 alkyl group, a straight-chain or branched C5-C17 alkenyl group, in particular a branched C4-C5 alkenyl group, or a phenyl group.

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

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

22. A kit for carrying out the process according to any one of claims 1 to 12, the kit comprising: - Part A, which contains (i) 10% to 89.99% by weight of a dihydroxypolydimethylsiloxane polymer having a viscosity of 3000 to 100000 mm2 / s measured at 25 °C, and (ii) 10% to 90% by weight of a mixture comprising at least one volatile solvent and a volatile organic substance capable of dissolving the dihydroxypolydimethylsiloxane polymer; - Part B, which contains (iii) 10% to 30% by weight of N-morpholinomethyltriethoxysilane, and (iv) 70% to 90% by weight of a non-functionalized polydimethylsiloxane silicone oil having a viscosity of 10 to 245 mm2 / s measured at 25 °C, which is capable of dissolving the N-morpholinomethyltriethoxysilane; It is characterized in that Part A further contains 0.01% to 5% by weight of a carboxylic acid and does not contain any metal catalyst, and Part A and Part B are physically separated from each other.

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