Silane type emulsion polymerization stabilizer, application and silicon-acrylate emulsion stabilized thereby

Abstract

The application relates to the technical field of high polymer compound synthesis, in particular to a silane type emulsion polymerization stabilizer, application and a silicone-acrylate emulsion stabilized by the same. The preparation steps of the silane type emulsion polymerization stabilizer are as follows: (1) an epoxy silane is subjected to ring-opening reaction and polyether amine to form a polyether silane-epoxy silane mixture, and (2) the mixture is prepared into a polyether silane-epoxy silane oligomer through condensation reaction. By optimizing the preparation raw materials and preparation method of the polyether silane-epoxy silane mixture, the use amount of the stabilizer is controlled, the emulsion stabilized by the stabilizer can exhibit excellent stability, and in addition, the stabilizer can also improve the physicochemical properties of the emulsion, such as hardness, adhesion and water resistance. The stabilizer is synthesized without inert solvent, the method is environment-friendly, simple and effective.

Description

Technical Field

[0001] This invention relates to the field of polymer synthesis technology, C08G65 / 00, specifically to a silane-type emulsion polymerization stabilizer, its application, and the silicone-acrylic emulsion stabilized by it. Background Technology

[0002] Emulsion polymerization is a commonly used polymerization process for synthesizing emulsion polymers. Stabilizers play a crucial role in emulsion polymerization, effectively preventing emulsion instability, enhancing polymer stability, and improving the physicochemical properties of the emulsion. Traditional emulsion polymerization stabilizers are mainly based on polymers such as polyvinyl alcohol and polyethers, but these still have shortcomings such as insufficient stability in practical applications.

[0003] Chinese patent CN103342782B discloses a silicone-modified acrylate emulsion, its preparation method, and the resulting water-based artificial stone. This patent mixes octamethylcyclotetrasiloxane D4, Y-methacryloyloxypropyltrimethoxysilane KH570, and hexamethyldisiloxane MM to form a siloxane intermediate emulsion, which is then used as a pre-emulsion in the preparation of a silicone-acrylic copolymer emulsion. The resulting silicone-modified acrylate emulsion exhibits good emulsion hardness, stain resistance, and water resistance, but its stabilizing effect on the emulsion is poor. Chinese patent CN104861107B discloses a method for preparing a silicone-acrylic fine emulsion, which improves the stability of the emulsion by adding acrylate monomers, organosilicon monomers, and stabilizers. The organosilicon monomers include functional organosilicon monomers selected from one of 3-(methacryloyloxy)propyltrimethoxysilane (MEMO), 3-(methacryloyloxy)propyltriethmethoxysilane, vinyltriisopropoxysilane, and vinyltriethoxysilane. However, the content of functional organosilicon monomers in this technology is the industry standard, approximately 5%, and this technology cannot solve the problem of a significant decrease in emulsion stability when using high levels of functional organosilicon monomers (≥10%). Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention first provides a silane-type emulsion polymerization stabilizer. The preparation steps of the silane-type emulsion polymerization stabilizer are as follows: (1) epoxy silane undergoes a ring-opening reaction and polyether amine to form a polyether silane-epoxy silane mixture; (2) the mixture is used to prepare a polyether silane-epoxy silane oligomer through a condensation reaction.

[0005] Further, step (1) is as follows: after mixing polyetheramine and epoxysilane, heat and react at 90-140℃ for 4-10h to obtain a polyethersilane-epoxysilane mixture.

[0006] Furthermore, in step (1), the heating temperature is 100-120℃ and the heating time is 5-8h.

[0007] Furthermore, the molar ratio of EO / PO in the polyetheramine is (19-41):(3-10), such as 19:3, 41:4, 33:10, 20:8, etc.

[0008] Furthermore, the weight-average molecular weight of the polyetheramine is 1000-3000, such as 1000, 2000, 3000, etc.

[0009] Further, the epoxysilane is selected from at least one of structure A or structure B, wherein structure A is:

[0010]

[0011] The structure B is:

[0012]

[0013] Furthermore, in structures A and B, R1, R2, R4, and R5 are independently selected from any one of C1-C20 alkyl groups, C2-C15 alkenyl groups, C1-C10 ester groups, and C2-C10 acyl groups.

[0014] Furthermore, the alkyl groups of the C1-C20 are including, but are not limited to, any one of methyl, ethyl, propyl, butyl, isopropyl, pentyl, isopentyl, tert-butyl, hexyl, heptyl, octyl, nonyl, and decyl.

[0015] Furthermore, R3 and R6 are independently selected from any one of C1-C30 alkyl groups, C1-C10 alkoxy groups, and C2-C15 alkenyl groups.

[0016] Preferably, R3 is selected from C1-C30 alkyl or C1-C10 alkoxy, more preferably from any one of methyl, ethyl, propyl, methoxy, ethoxy, and propoxy.

[0017] Preferably, R6 is selected from C1-C10 alkoxy groups, and more preferably from any one of methoxy, ethoxy, and propoxy groups.

[0018] Furthermore, x is an integer from 0 to 15, and y is an integer from 1 to 9.

[0019] Preferably, x is an integer from 1 to 10, and y is an integer from 1 to 6.

[0020] More preferably, x is an integer from 2 to 5, and y is an integer from 1 to 4.

[0021] In a preferred embodiment, x is 3 and y is 1 or 2.

[0022] Furthermore, n is an integer from 1 to 8, preferably an integer from 1 to 6, and more preferably an integer from 2 to 5.

[0023] In a preferred embodiment, n is 2.

[0024] Further, the epoxy silane having structure A is selected from at least one of 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-glycidyl etheroxypropyltri-n-propoxysilane, 3-glycidyl etheroxypropyltriisopropoxysilane, 3-glycidyl etheroxypropyltri-n-butoxysilane, and 3-glycidyl etheroxypropyltriisobutoxysilane.

[0025] Preferably, the epoxy silane having structure A is selected from any one of 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, and 3-glycidyl etheroxypropyltriethoxysilane.

[0026] Further, the epoxy silane having structure B is selected from at least one of 2-(3,4-epoxycyclohexyl)ethanedimethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethanedimethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltri-n-propoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltriisopropoxysilane, γ-(3,4-epoxycyclohexyl)-propyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)-propyltriethoxysilane, γ-(3,4-epoxycyclohexyl)-propyltri-n-propoxysilane, and γ-(3,4-epoxycyclohexyl)-propyltriisopropoxysilane.

[0027] Preferably, the epoxy silane having structure B is 2-(3,4-epoxycyclohexyl)ethoxysilane or 2-(3,4-epoxycyclohexyl)ethoxysilane.

[0028] Further, the mass ratio of the polyetheramine to the epoxysilane is 100:(2-40), preferably 100:(5-20), and can be selected as 100:5, 100:10, 100:15, 100:20, etc.

[0029] The oligomer of polyetheramine and epoxysilane in this application, polyethersilane, contains numerous polyethylene glycol segments in its molecular chain. These polyethylene glycol segments participate in the polymerization of silicone-acrylic emulsion monomers, preventing the condensation of some monomers, such as acrylate silanes, through steric hindrance, thus avoiding demulsification caused by excessive condensation of the latter. Furthermore, polyethersilane molecules not involved in the reaction encapsulate the silicone-acrylic emulsion through their polar groups, preventing interactions between adjacent silicone-acrylic latex particles and collectively promoting system equilibrium. Notably, the participation of silane segments in the polyethersilane in the polymerization reaction of silicone-acrylic emulsion monomers can increase the physicochemical properties of the emulsion, such as hardness, adhesion, and water resistance. The relative amounts of polyetheramine and epoxysilane determine the number of polyethylene glycol segments and silicon-oxygen bonds in the polymer; only when the amounts of both are appropriate can the prepared polyethersilane exert its optimal effect in the above process.

[0030] In one embodiment, when the weight-average molecular weight of the polyetheramine is 1000-2000, the epoxysilane is selected from either structure A or structure B.

[0031] In one embodiment, when the weight-average molecular weight of the polyetheramine is 2100-3000, the epoxysilane is selected from any one of structure B.

[0032] Further, step (2) is as follows: at room temperature, 100 parts by mass of deionized water are added to the reactor, and 0.8-3 times the mass of water of polyether silane-epoxy silane mixture is added under stirring. The hydrolysis is deheated, and the process ends when the temperature gradually decreases and returns to room temperature, thus obtaining polyether silane-epoxy silane oligomer.

[0033] Furthermore, in step (2), the stirring speed is 150-1000 rpm, preferably 200-500 rpm.

[0034] Furthermore, the mass concentration of the polyether silane-epoxy silane oligomer is 30-70%.

[0035] Secondly, this application also provides the application of the silane-type emulsion polymerization stabilizer in the preparation of silicone-acrylic emulsions.

[0036] Furthermore, the amount of the silane-type emulsion polymerization stabilizer accounts for 2-20% of the total mass of the silicone-acrylic emulsion raw material, preferably 3-15%, and more preferably 5-10%.

[0037] Furthermore, in the preparation process of silicone-acrylic emulsion, the silane-type emulsion polymerization stabilizer needs to be added before the monomer is added.

[0038] Furthermore, this application also provides a silicone-acrylic emulsion stabilized by the silane-type emulsion polymerization stabilizer.

[0039] Furthermore, the raw materials for preparing the silicone-acrylic emulsion include: 1-6% emulsifier, 2-20% silane-type emulsion polymerization stabilizer, 0.3-3% initiator, 30-45% monomer, and deionized water to make up the balance.

[0040] Preferably, the raw materials for preparing the silicone-acrylic emulsion include: 2-3.5% emulsifier, 5-10% silane-type emulsion polymerization stabilizer, 0.5-1.0% initiator, 30-45% monomer, and deionized water to make up the balance.

[0041] Furthermore, the emulsifier is selected from anionic emulsifiers and / or nonionic emulsifiers, preferably anionic emulsifiers and nonionic emulsifiers.

[0042] Further, the mass ratio of the anionic emulsifier to the nonionic emulsifier is (0.5-3):(0.5-3), preferably (0.5-2.5):(0.5-2.0).

[0043] Furthermore, the anionic emulsifier is selected from at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecyl diphenyl ether disulfonate, sodium alkyl polyoxyethylene ether sulfate, ammonium alkyl polyoxyethylene ether sulfate, and sodium succinate sulfonate, preferably sodium dodecylbenzenesulfonate.

[0044] Furthermore, the nonionic emulsifier is selected from at least one of dehydrated sorbitan fatty acid ester, sorbitan fatty acid ester, alkylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether, preferably alkylphenol polyoxyethylene ether.

[0045] Furthermore, the initiator is selected from at least one of peroxides and azo compounds.

[0046] Furthermore, the peroxide initiator is selected from persulfates, including but not limited to at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0047] Furthermore, the azo initiator is selected from at least one of azobisisopropylimidazoline hydrochloride (AIBI), azobisisobutylimidazoline hydrochloride (AIBA), and diiso(N-aminoethyl)butamidine (ABEA).

[0048] Furthermore, the monomers include, but are not limited to, at least one of hard monomers, soft monomers, and functional monomers.

[0049] Further, the monomers include, but are not limited to, at least two of styrene, methyl methacrylate, ethyl methacrylate, n-butyl acrylate, ethyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, n-octyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, acrylamide, N-butoxymethyl (methyl)acrylamide, N-hydroxymethylacrylamide, diacetone acrylamide, ethyl acetoacetate methacrylate, divinylbenzene, methacrylic acid, acrylic acid, methylene succinic acid, styrene sulfonic acid, sodium vinyl sulfonate, and acrylate silanes.

[0050] Further, the monomer includes acrylate silanes; the acrylate silanes include, but are not limited to, at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, and γ-methacryloyloxypropyltrimethoxysilane, preferably including γ-methacryloyloxypropyltrimethoxysilane.

[0051] Furthermore, the amount of acrylic silane added accounts for more than 5% of the total mass of the raw materials used to prepare the silicone-acrylic emulsion, preferably more than 10%, more preferably 10-15%, and can be selected from 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, etc.

[0052] Furthermore, the preparation method of the silicone-acrylic emulsion is as follows:

[0053] S1: Mix the monomers evenly to obtain a monomer mixture; mix the initiator with 1 / 8 to 1 / 5 of the mass of deionized water evenly to obtain an initiator aqueous solution for later use;

[0054] S2: Mix the emulsifier, silane emulsion polymerization stabilizer and the remaining deionized water, stir and heat to 27-50℃;

[0055] S3: After the temperature rises to 80℃, add 1 / 4 to 2 / 5 of the mass of the initiator aqueous solution while stirring;

[0056] S4: Simultaneously add 1 / 5 to 4 / 5 of the mass of the monomer mixture and the initiator aqueous solution, and complete the addition within 2 to 2.5 hours;

[0057] S5: Add the remaining initiator aqueous solution, keep warm for 1-5 hours, and then cool to below 40°C; to obtain silicone-acrylic emulsion.

[0058] Furthermore, the stirring speed during the reaction is 100-500 rpm.

[0059] Beneficial effects

[0060] 1. The stabilizer in this application uses polyether silane-epoxy silane oligomers as the main component. Through the protection of the polyethylene glycol segments, the polyether silane-epoxy silane oligomers react with the acrylic silane monomer in the silicone-acrylic emulsion, improving the steric barrier effect and preventing demulsification caused by the polycondensation of acrylic silanes. Even when the acrylic silane content is as high as 15%, the prepared emulsion still exhibits excellent stability. Furthermore, this stabilizer can improve the physicochemical properties of the emulsion, such as hardness, adhesion, and water resistance. The stabilizer is synthesized without inert solvents, a method that is environmentally friendly, simple, and effective.

[0061] 2. This application strictly optimizes the molecular structure of epoxy silane to react with suitable polyether silane, controls the flexibility and molecular chain mobility of the prepared stabilizer, thereby improving its stabilizing effect on silicone-acrylic emulsion and enhancing the adhesion and water resistance of the film layer after the silicone-acrylic emulsion is formed.

[0062] 3. This application strictly optimizes the relative amounts of polyetheramine and epoxysilane in the preparation method of polyether silane-epoxysilane mixture and oligomer. By controlling the number of polyethylene glycol segments and the number of siloxane bonds, the stable storage performance of the silicone-acrylic emulsion is improved, and demulsification is avoided. Detailed Implementation

[0063] Example

[0064] Examples 1-5

[0065] Examples 1-5 provide a polyether silane-epoxy silane mixture, and the details of the raw materials for preparing the polyether silane-epoxy silane mixture are shown in Table 1;

[0066] The preparation method of the polyether silane-epoxy silane is as follows: polyether amine and epoxy silane are added to a reactor, stirred evenly at a speed of 300 r / min, and reacted at 80℃ for 5 h to finally obtain a polyether silane-epoxy silane mixture.

[0067] Table 1

[0068]

[0069] Examples 6-10

[0070] Examples 6-10 provide a silane-type emulsion polymerization stabilizer—polyether silane-epoxy silane oligomer;

[0071] The 6-10 polyether silane-epoxy silane oligomers were prepared from the polyether silane-epoxy silane mixtures of Examples 1-5 according to the following method: at room temperature, 100 parts by mass of deionized water were added to the reactor, and at a rotation speed of 400 r / min, 100 parts by mass of the polyether silane-epoxy silane mixture were added. The hydrolysis was deheated, and the mixture was allowed to gradually decrease and return to room temperature to obtain the polyether silane-epoxy silane oligomers.

[0072] Examples 11-15

[0073] Examples 11-15 provide a silicone-acrylic emulsion stabilized by a silane-type emulsion polymerization stabilizer. The raw material information for preparation is shown in Table 2.

[0074] The preparation method of the silicone-acrylic emulsion is as follows:

[0075] S1: Mix the monomers evenly to obtain a monomer mixture; mix the initiator with 1 / 10 of the mass of deionized water evenly to obtain an initiator aqueous solution for later use;

[0076] S2: Mix the emulsifier, silane emulsion polymerization stabilizer and the remaining deionized water, and stir at 300 rpm to raise the temperature to 30°C;

[0077] S3: After the temperature rises to 80℃, add 1 / 5 of the mass of the initiator aqueous solution while stirring;

[0078] S4: Simultaneously add 3 / 5 of the mass of the monomer mixture and the initiator aqueous solution, controlling the addition to be completed within 2.5 hours;

[0079] S5: Add the remaining initiator aqueous solution, keep warm for 2 hours, and then cool to below 40°C; to obtain silicone-acrylic emulsion.

[0080] Table 2

[0081]

[0082]

[0083] Comparative Example 1

[0084] It is basically the same as Example 11, except that the amount of stabilizer added is 0.

[0085] Comparative Example 2

[0086] It is basically the same as Example 11, except that the stabilizer is replaced by epoxy silane (Shin-Etsu KBM-403).

[0087] Comparative Example 3

[0088] It is basically the same as Example 11, except that the stabilizer is replaced by the polyether silane-epoxy silane mixture of Example 1.

[0089] Performance testing methods:

[0090] 1. Silicone-acrylic emulsion:

[0091] (1) Gel ratio: The synthesized silicone-acrylic emulsion was filtered through a 1000-mesh filter, and the resulting filter material was dried at 120°C for 24 hours. The filter material was weighed, and its percentage of the theoretical solid content of the emulsion was calculated.

[0092] (2) Freeze-thaw stability: The synthesized emulsion was frozen at a low temperature of -(20±1)℃ for 18h and then melted at 20℃ for 6h. If there was no emulsion breakage, it was considered to have passed the test once.

[0093] 2. Coating performance:

[0094] Add 5% dodecyl alcohol ester (film-forming aid) to the silicone-acrylic emulsions of Examples 11-15, stir evenly at 500 r / min to prepare the corresponding coatings, and measure the various properties of the coatings.

[0095] (1) Hardness: The hardness of paint film was determined according to the standard GB / T 6739-2006 Pencil method for determination of paint film hardness.

[0096] (2) Adhesion: The adhesion was determined according to the standard GB / T 9286-2021 Cross-cut test for paints and varnishes.

[0097] (3) Water resistance: The test shall be conducted in accordance with the standard GB / T1733-1993 Test Method for Water Resistance of Coating Film.

[0098] The specific test results are shown in Table 3.

[0099] Performance test results:

[0100] Table 3

[0101]

[0102]

[0103] Summary: Table 3 shows that the emulsions and coatings prepared in Examples 11-15 differ significantly from those in Comparative Examples 1-3. In Comparative Example 1, which received no treatment, the emulsion demulsified, and the polymerization process was unstable. The emulsion in Comparative Example 2, treated only with 3-glycidyl etheroxypropyltrimethoxysilane (Shin-Etsu KBM-403), was not stable. The silicone-acrylic emulsion in Comparative Example 3, which was not stabilized by the condensed polyether silane-epoxy silane mixture, had a gel rate as high as 17.8%, could only withstand three freeze-thaw cycles, and exhibited low hardness, adhesion, and water resistance.

[0104] The silicone-acrylic emulsions of Examples 11-15 of this application exhibit excellent gelation rate and freeze-thaw stability. Even when the amount of γ-methacryloyloxypropyltrimethoxysilane, a monomer capable of slow cross-linking, is added up to 15% of the emulsion preparation raw materials, the emulsion still demonstrates excellent stability. Notably, after film formation, the silicone-acrylic emulsion of this application also possesses hardness, adhesion (including adhesion after freeze-thaw storage), and water resistance.

Claims

1. A silicone-acrylic emulsion, characterized in that, The raw materials for preparing the silicone-acrylic emulsion include: 1-6% emulsifier, 2-20% silane emulsion polymerization stabilizer, 0.3-3% initiator, 30-45% monomer, and deionized water to make up the balance; The preparation steps of the silane-type emulsion polymerization stabilizer are as follows: (1) epoxy silane undergoes a ring-opening reaction and polyether amine to form a polyether silane-epoxy silane mixture; (2) the mixture is used to prepare a polyether silane-epoxy silane oligomer through a condensation reaction. The EO / PO molar ratio in the polyetheramine is (19-41):(3-10), and the weight-average molecular weight of the polyetheramine is 1000-3000. The epoxysilane is selected from at least one of structure A or structure B, wherein structure A is: ； The structure B is: ； R1, R2, R4, and R5 are independently selected from any one of C1-C20 alkyl, C2-C15 alkenyl, C1-C10 ester, and C2-C10 acyl; R3 and R6 are independently selected from any one of C1-C30 alkyl, C1-C10 alkoxy, and C2-C15 alkenyl; x is an integer from 0 to 15, y is an integer from 1 to 9, and n is an integer from 1 to 8; The monomer includes acrylic silane; the amount of acrylic silane added accounts for more than 10% of the total mass of the raw materials used in the preparation of the silicone-acrylic emulsion.

2. The silicone-acrylic emulsion according to claim 1, characterized in that, R3 is selected from C1-C30 alkyl or C1-C10 alkoxy groups, and R6 is selected from C1-C10 alkoxy groups.

3. The silicone-acrylic emulsion according to claim 2, characterized in that, x is an integer from 2 to 5, y is an integer from 1 to 4, and n is an integer from 2 to 5.

4. The silicone-acrylic emulsion according to claim 1, characterized in that, The mass ratio of the polyetheramine to the epoxysilane is 100:(2-40).

5. The silicone-acrylic emulsion according to claim 4, characterized in that, The mass ratio of the polyetheramine to the epoxysilane is 100:(5-20).

6. The silicone-acrylic emulsion according to claim 1, characterized in that, Step (2) is as follows: At room temperature, add 100 parts by mass of deionized water to the reactor, and add 0.8-3 times the mass of water of polyether silane-epoxy silane mixture while stirring. The water is deheated and the mixture is allowed to gradually decrease and return to room temperature to obtain polyether silane-epoxy silane oligomer.

7. The silicone-acrylic emulsion according to claim 1, characterized in that, The amount of acrylic silane added accounts for 10-15% of the total mass of the raw materials used in the preparation of the silicone-acrylic emulsion.

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