An mq silicone resin for medical silicone pressure-sensitive adhesive and a preparation method thereof

Abstract

The application belongs to the field of medical silicone pressure-sensitive adhesive preparation, and particularly relates to a kind of medical silicone pressure-sensitive adhesive MQ silicone resin and its preparation method, comprising the following steps: mixing catalyst, deionized water, solvent I, adding into a reaction vessel, and stirring in advance;Adding component A, and reacting;When the temperature in the reaction vessel does not change, continue to stir;Adding component B and solvent II, increasing the temperature, and keeping the temperature to continue the reaction, after the reaction, quickly reduce to room temperature, and add extractant;Pour the reaction liquid after the reaction into a separatory funnel, then discharge the acid liquid, add baking soda to adjust pH, so that the pH is adjusted to neutral;Add anhydrous magnesium sulfate and activated carbon, and carry out water absorption, decolorization and odor absorption, then place in a vacuum drying oven to remove the solvent, and the MQ silicone resin is obtained.The MQ silicone resin prepared by the application can not only improve the initial adhesion of the silicone resin, but also has good holding adhesion for the prepared pressure-sensitive adhesive product.

Description

Technical Field

[0001] This invention belongs to the field of medical silicone pressure-sensitive adhesive preparation, specifically relating to an MQ silicone resin for medical silicone pressure-sensitive adhesives and its preparation method. Background Technology

[0002] Medical pressure-sensitive tape, as an indispensable part of the medical field, is becoming increasingly important with the advancement of medical technology and the significant improvement of public health awareness. In modern medical practice, this tape plays a crucial role in wound healing, dressing fixation, and skin protection due to its unique properties and wide applicability.

[0003] Silicone pressure-sensitive adhesives are a type of pressure-sensitive adhesive primarily used in the manufacture of pressure-sensitive tapes. Based on their main resin composition, pressure-sensitive adhesives can be divided into two categories: rubber-based and resin-based. Rubber-based adhesives can be further divided into natural rubber and synthetic rubber; resin-based adhesives mainly include acrylic, silicone, and polyurethane types.

[0004] The choice of medical pressure-sensitive adhesive is directly related to skin condition. It's important to note that excessively strong adhesion can cause epidermal peeling, some pressure-sensitive adhesives can cause allergic reactions, and poor breathability can lead to skin maceration. Different medical pressure-sensitive adhesives have different effects on the skin; patients with poor skin conditions should carefully consider the type of pressure-sensitive adhesive they choose. Silicone pressure-sensitive adhesives, due to their mild adhesion and minimal change in adhesive properties over time, can be reused without causing skin peeling.

[0005] The properties and applications of MQ silicone resin mainly depend on its synthesis process conditions and the type and number of organic groups in the molecule, i.e., the ratio of M-units to Q-units; the organic group R mainly increases compatibility with other components and acts as a thickener; SiO 4 / 2 Linkages primarily serve as reinforcements to improve the strength of composite materials.

[0006] Currently, with the increasing market competition, medical pressure-sensitive adhesive products are facing increasingly stringent performance requirements, such as functionality, durability, strength, reliability, and safety. In this process, the silicone MQ resin used as a raw material must not only be non-toxic and functional, but its preparation process must also be strictly controlled to find an ideal silicone MQ resin as a raw material for preparing medical pressure-sensitive adhesives, thereby enhancing the product's market competitiveness. Based on the above, the development of silicone MQ resin has become a highly anticipated research topic. For example:

[0007] Chinese Patent Publication No. CN104072776B discloses an MQ silicone resin for preparing medical pressure-sensitive adhesive and its preparation process. The MQ silicone resin is prepared by reacting the following components: Component A: hydrochloric acid solution; Component B: silicate solution; Component C: siloxane with the general formula X3SiOSiX3 and chlorosilane with the general formula Y3SiCl; Component D: siloxane with the general formula Z... 0 The trifunctional silane of Si(OZ)3; component E: solvent; the general formula of the prepared MQ silicone resin is: (R 1 3SiO 1 / 2 )a(R 2 Si 3 / 2 )b(SiO 4 / 2 However, this invention generates a large amount of wastewater, causing serious pollution and resulting in high costs for subsequent wastewater treatment.

[0008] Chinese Patent Publication No. CN114316269A discloses a method for preparing MQ resin for pressure-sensitive adhesives. The preparation process includes: a) preparing an MQ resin solution under acidic conditions using silicate ester and a capping agent as raw materials; b) preparing a hydrogen-containing capping agent using alkoxysilane and hydrogen-containing silane as raw materials; c) treating the obtained MQ resin solution with the self-made hydrogen-containing capping agent under the action of a catalyst, and removing excess solvent and small molecules under reduced pressure to obtain the MQ resin. The MQ resin prepared by this invention has a hydroxyl content of less than 0.3 wt% and an alkoxy content of less than 0.5 wt%. However, the prepared silicone resin still needs further optimization in terms of molecular weight and dispersion index to improve product performance.

[0009] In addition, existing technologies also have the following drawbacks:

[0010] 1. The traditional preparation process of MQ silicone resin involves acid water discharge, complex process, high energy consumption, and the presence of gels and low molecular weight substances that affect compatibility and performance.

[0011] 2. Residual silanol groups can decompose at high temperatures, producing bubbles and residues, which may pose safety risks for medical products.

[0012] 3. Insufficient performance of MQ resin, such as low peel strength and low light transmittance, may affect the effectiveness and appearance of medical patches. Summary of the Invention

[0013] To address the shortcomings of the prior art, this invention provides an MQ silicone resin for medical silicone pressure-sensitive adhesives and its preparation method.

[0014] The specific technical solution is as follows:

[0015] The first objective of this invention is to provide a method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives, comprising the following steps by weight:

[0016] (1) Preparation stage: First, mix 2-3 parts of catalyst, 100-140 parts of deionized water and 60-70 parts of solvent I, add them to the reaction vessel, stir for 10-20 minutes beforehand, and keep the temperature inside the reaction vessel at 20-25℃.

[0017] (2) Self-polymerization stage: Add 260 parts of component A, control the temperature inside the reaction vessel at 30-35℃, and react for 60-90 minutes. When the temperature inside the reaction vessel does not change, continue stirring for 20-30 minutes.

[0018] (3) Copolymerization stage: Add 102-131 parts of component B and 30-50 parts of solvent II, raise the temperature, control the temperature inside the reaction vessel at 50-65℃, and continue the reaction at this temperature for 3-4 hours, and then add 120-160 parts of extractant;

[0019] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a separatory funnel, then release the acid solution, add baking soda to adjust the pH to neutral; add 12 parts of anhydrous magnesium sulfate and 2 parts of activated carbon to absorb water, decolorize and absorb odor, then place it in a vacuum drying oven at 150-170℃ to remove the solvent, and the product is obtained.

[0020] Furthermore, in step (4), before placing the container in a vacuum drying oven to remove the solvent, the following steps are also included:

[0021] Step (5) Reprocessing stage I: Add 15-25 parts of component B and 8-12 parts of catalyst, control the temperature inside the reaction vessel at 30-40℃, and carry out the reaction for 5-6 hours;

[0022] Step (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to neutral, add 50 parts of anhydrous magnesium sulfate and 2 parts of activated carbon to absorb water, decolorize and absorb odor.

[0023] Furthermore, in step (1) or step (5), the catalyst is one or more of hydrochloric acid, concentrated sulfuric acid, formic acid, acetic acid, and trifluoromethanesulfonic acid.

[0024] Furthermore, in step (1), solvent I is one or both of isopropanol and anhydrous ethanol.

[0025] Furthermore, in step (1), the reaction vessel is a four-necked flask equipped with a stirrer, a thermometer, and a nitrogen port.

[0026] Furthermore, in step (2), component A is one or both of ethyl silicate and methyl silicate.

[0027] Further, in step (3) or step (5), component B is: a siloxane with the general formula X3SiOSiX3 or a chlorosilane with the general formula Y3SiCl, wherein X is derived from one of the monovalent hydrocarbon groups and Y is derived from one of the monovalent hydrocarbon groups.

[0028] Furthermore, in step (3), solvent II is one or both of toluene and xylene.

[0029] Furthermore, in step (3), the extractant is one or both of toluene and xylene.

[0030] The second objective of this invention is to provide an MQ silicone resin for medical silicone pressure-sensitive adhesives, which is prepared using the preparation method described above.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) The MQ silicone resin of the present invention is prepared by using silicate ester. The preparation of MQ silicone resin by tetraethyl orthosilicate method has the advantages of high yield and controllable average molar mass of product, as well as low wastewater production. The wide molecular weight distribution can not only improve the initial tack of silicone resin, but also has good holding power for the pressure-sensitive adhesive product.

[0033] (2) The MQ silicone resin for medical silicone pressure-sensitive adhesive prepared by the present invention is safe, reliable and non-toxic. Since silicate ester is used as the source of Q chain segment in its preparation, it can not only improve the initial tack of silicone resin, but also have good holding power for the pressure-sensitive adhesive product. The performance is very stable and suitable for widespread use, especially in fields with high safety requirements such as medical and hygiene products.

[0034] (3) The preparation method of MQ silicone resin provided by the present invention is simple and effectively meets the performance testing requirements of pressure-sensitive adhesives in the medical field, greatly expanding the application scope and having broad application prospects. Detailed Implementation

[0035] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0036] In each embodiment, the preparation formula of MQ silicone resin for the medical silicone pressure-sensitive adhesive is as follows:

[0037]

[0038] Example 1

[0039] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0040] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0041] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0042] (3) Copolymerization stage: Add 124g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0043] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0044] Example 2

[0045] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0046] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0047] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0048] (3) Copolymerization stage: Add 120g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0049] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0050] Example 3

[0051] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0052] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0053] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0054] (3) Copolymerization stage: Add 115g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0055] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0056] Example 4

[0057] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0058] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0059] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0060] (3) Copolymerization stage: Add 110g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0061] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0062] Example 5

[0063] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0064] (1) Preparation stage: First, mix 2g of concentrated sulfuric acid, 100g of water and 60g of anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 15 minutes beforehand and keep the temperature inside the flask at 23℃.

[0065] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 32℃, and react for 70min. When the temperature inside the flask does not change, continue stirring for 25min.

[0066] (3) Copolymerization stage: Add 102g hexamethyldisiloxane and 30g xylene, raise the temperature to 55℃, and continue the reaction at this temperature for 3.5h. Then add 120g xylene for extraction.

[0067] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 150℃ to remove the solvent, and the product is obtained.

[0068] Example 6

[0069] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0070] (1) Preparation stage: First, mix 3g concentrated sulfuric acid, 140g water and 70g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 10 minutes beforehand and keep the temperature inside the flask at 22℃.

[0071] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 34℃, and react for 80min. When the temperature inside the flask does not change, continue stirring for 25min.

[0072] (3) Copolymerization stage: Add 131g hexamethyldisiloxane and 50g xylene, raise the temperature to 60℃, and continue the reaction at this temperature for 4h. Then add 160g xylene for extraction.

[0073] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 165℃ to remove the solvent, and the product is obtained.

[0074] Example 7

[0075] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0076] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 15 minutes beforehand and keep the temperature inside the flask at 25℃.

[0077] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 35℃, and react for 90min. When the temperature inside the flask does not change, continue stirring for 30min.

[0078] (3) Copolymerization stage: Add 124g of trimethylchlorosilane and 30g of xylene, raise the temperature to 65℃, and continue the reaction at this temperature for 4h. Then add 150g of xylene for extraction.

[0079] (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 170℃ to remove the solvent, and the product is obtained.

[0080] Example 8

[0081] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0082] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0083] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0084] (3) Copolymerization stage: Add 124g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0085] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0086] (5) Reprocessing stage I: Add 20g hexamethyldisiloxane and 10g concentrated sulfuric acid, raise the temperature to 40℃, and maintain this temperature to continue the reaction for 6h;

[0087] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0088] Example 9

[0089] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0090] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0091] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0092] (3) Copolymerization stage: Add 120g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0093] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0094] (5) Reprocessing stage I: Add 20g hexamethyldisiloxane and 10g concentrated sulfuric acid, raise the temperature to 40℃, and maintain this temperature to continue the reaction for 6h;

[0095] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0096] Example 10

[0097] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0098] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0099] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0100] (3) Copolymerization stage: Add 115g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0101] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0102] (5) Reprocessing stage I: Add 20g hexamethyldisiloxane and 10g concentrated sulfuric acid, raise the temperature to 40℃, and maintain this temperature to continue the reaction for 6h;

[0103] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0104] Example 11

[0105] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0106] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 20 minutes beforehand and keep the temperature inside the flask at 20℃.

[0107] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 30℃, and react for 60min. When the temperature inside the flask does not change, continue stirring for 20min.

[0108] (3) Copolymerization stage: Add 110g hexamethyldisiloxane and 30g xylene, raise the temperature to 50℃, and continue the reaction at this temperature for 3h. Then add 150g xylene for extraction.

[0109] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0110] (5) Reprocessing stage I: Add 20g hexamethyldisiloxane and 10g concentrated sulfuric acid, raise the temperature to 40℃, and maintain this temperature to continue the reaction for 6h;

[0111] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 160℃ to remove the solvent, and the product is obtained.

[0112] Example 12

[0113] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0114] (1) Preparation stage: First, mix 2g of concentrated sulfuric acid, 100g of water and 60g of anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 15 minutes beforehand and keep the temperature inside the flask at 23℃.

[0115] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 32℃, and react for 70min. When the temperature inside the flask does not change, continue stirring for 25min.

[0116] (3) Copolymerization stage: Add 102g hexamethyldisiloxane and 30g xylene, raise the temperature to 55℃, and continue the reaction at this temperature for 3.5h. Then add 120g xylene for extraction.

[0117] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0118] (5) Reprocessing stage I: Add 15g hexamethyldisiloxane and 8g concentrated sulfuric acid, raise the temperature to 40℃, and continue the reaction at this temperature for 5h;

[0119] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 150℃ to remove the solvent, and the product is obtained.

[0120] Example 13

[0121] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0122] (1) Preparation stage: First, mix 3g concentrated sulfuric acid, 140g water and 70g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 10 minutes beforehand and keep the temperature inside the flask at 22℃.

[0123] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 34℃, and react for 80min. When the temperature inside the flask does not change, continue stirring for 25min.

[0124] (3) Copolymerization stage: Add 131g hexamethyldisiloxane and 50g xylene, raise the temperature to 60℃, and continue the reaction at this temperature for 4h. Then add 160g xylene for extraction.

[0125] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0126] (5) Reprocessing stage I: Add 25g hexamethyldisiloxane and 12g concentrated sulfuric acid, raise the temperature to 30°C, and maintain this temperature to continue the reaction for 6h;

[0127] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 165℃ to remove the solvent, and the product is obtained.

[0128] Example 14

[0129] A method for preparing MQ silicone resin for medical silicone pressure-sensitive adhesives includes the following steps:

[0130] (1) Preparation stage: First, mix 2.5g concentrated sulfuric acid, 120g water and 65g anhydrous ethanol and add them to a four-necked flask equipped with a stirrer, thermometer and nitrogen port. Stir for 15 minutes beforehand and keep the temperature inside the flask at 25℃.

[0131] (2) Self-polymerization stage: Add 260g of tetraethyl orthosilicate, control the temperature inside the flask at 35℃, and react for 90min. When the temperature inside the flask does not change, continue stirring for 30min.

[0132] (3) Copolymerization stage: Add 124g of trimethylchlorosilane and 30g of xylene, raise the temperature to 65℃, and continue the reaction at this temperature for 4h. Then add 150g of xylene for extraction.

[0133] (4) Post-treatment stage: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 12g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor.

[0134] (5) Reprocessing stage I: Add 20g hexamethyldisiloxane and 10g concentrated sulfuric acid, raise the temperature to 30℃, and maintain this temperature to continue the reaction for 5h;

[0135] (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a pear-shaped separatory funnel, then release the acid solution, add baking soda to adjust the pH to 7, add 50g of anhydrous magnesium sulfate and 2g of activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven at 170℃ to remove the solvent, and the product is obtained.

[0136] test:

[0137] The silicone resins prepared in each embodiment were tested as pressure-sensitive adhesives. The pressure-sensitive adhesive formulations are as follows:

[0138] Component A': First, dissolve the silicone resins prepared in each example in toluene, then add hydroxyl polysiloxane (molecular weight 700,000-900,000), disperse evenly (mass ratio of the two is 1.1:1, and the solid content of the evenly dispersed resin is 30%), add 0.02g of chloroplatinic acid catalyst, and react at 100°C for 4 hours to obtain a weakly cross-linked component A'.

[0139] Component B': 10% BPO (benzoyl peroxide) crosslinking agent;

[0140] Component B' was added to the weakly cross-linked component A' at a concentration of 2%, and the mixture was stirred until homogeneous to obtain an organosilicon pressure-sensitive adhesive. The prepared organosilicon pressure-sensitive adhesive was uniformly coated onto the surface of a 125 μm thick polyimide film, with an adhesive thickness of 30 μm. After being heated in an oven at 150℃ for 5 minutes, a pressure-sensitive tape was obtained.

[0141] Initial tack was tested according to GB / T4852-2022 Test Method for Initial Tack of Pressure-Sensitive Adhesive Tape (Rolling Ball Method);

[0142] The tackiness was tested according to GB / T4851-2014 Test Method for Adhesive Tape Holding Power;

[0143] The peel force was tested according to GB / T2792-2014 Test Method for Peel Strength of Adhesive Tapes.

[0144] The test results for each embodiment are shown in Table 1.

[0145] Table 1 Test data for each embodiment

[0146]

[0147] Comparing the test data in Table 1, it can be concluded from Examples 1-4 that the peel force of the pressure-sensitive adhesive decreases as the amount of end-capping agent B component added to the silicone resin decreases; it can be concluded from Examples 8-11 that after reprocessing the silicone resin, the peel force of the pressure-sensitive adhesive decreases as the amount of end-capping agent B component added to the silicone resin decreases; it can be concluded from Examples 7 and 14 that there is no significant difference in peel force between the silicone resin prepared using chlorosilane as an end-capping agent and the silicone resin prepared using siloxane as an end-capping agent; and it can be concluded from Examples 1-14 that the pressure-sensitive adhesives made using the silicone resin of the present invention have good holding power; and under the condition that the amount of end-capping agent B component added to the silicone resin is the same, the peel force of the pressure-sensitive adhesive prepared by the reprocessed silicone resin is higher than that of the pressure-sensitive adhesive prepared by the unreprocessed silicone resin.

[0148] In summary, the MQ silicone resin prepared by this invention has the advantages of high yield (over 90%), controllable average molar mass of the product (around 4000-6000), and low wastewater production. Its wide molecular weight distribution and low hydroxyl content not only improve the initial tack of the silicone resin but also provide good holding power for the resulting pressure-sensitive adhesive products. The preparation method of the MQ silicone resin for medical pressure-sensitive adhesives of this invention is simple, effectively meets the performance testing requirements of pressure-sensitive adhesives in the medical field, greatly expands its application scope, and has broad application prospects.

[0149] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing MQ silicone resin for medical organosilicon pressure-sensitive adhesives, characterized in that, By weight, the following steps are included: (1) Preparation stage: First, mix 2-3 parts of catalyst, 100-140 parts of deionized water and 60-70 parts of solvent I, add them to the reaction vessel, stir for 10-20 minutes beforehand, and keep the temperature inside the reaction vessel at 20-25℃. (2) Self-polymerization stage: Add 260 parts of component A, control the temperature inside the reaction vessel at 30-35℃, and react for 60-90 minutes. When the temperature inside the reaction vessel does not change, continue stirring for 20-30 minutes. (3) Copolymerization stage: Add 102-131 parts of component B and 30-50 parts of solvent II, raise the temperature, control the temperature inside the reaction vessel at 50-65℃, and continue the reaction at this temperature for 3-4 hours. After the reaction is completed, quickly lower the temperature to room temperature, and then add 120-160 parts of extractant. (4) Post-processing stage: Pour the reaction solution after the reaction is completed into a separatory funnel, then release the acid solution, add baking soda to adjust the pH to neutral; add anhydrous magnesium sulfate and activated carbon to absorb water, decolorize and absorb odor, and then place it in a vacuum drying oven to remove the solvent, and the product is obtained. In step (1), the catalyst is concentrated sulfuric acid; In step (2), component A is ethyl silicate; In step (3), component B is: a siloxane with the general formula X3SiOSiX3 or a chlorosilane with the general formula Y3SiCl, wherein X is derived from one of the monovalent hydrocarbon groups and Y is derived from one of the monovalent hydrocarbon groups.

2. The preparation method of MQ silicone resin for medical organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, In step (4), before placing the container in a vacuum drying oven to remove the solvent, the following steps are also included: Step (5) Reprocessing stage I: Add 15-25 parts of component B and 8-12 parts of catalyst, control the temperature inside the reaction vessel at 30-40℃, and carry out the reaction for 5-6 hours; Step (6) Reprocessing stage II: Pour the reaction solution after the reaction is completed into a separatory funnel, then release the acid solution, add baking soda to adjust the pH to neutral; add anhydrous magnesium sulfate and activated carbon to absorb water, decolorize and absorb odor.

3. The preparation method of MQ silicone resin for medical organosilicon pressure-sensitive adhesive according to claim 2, characterized in that, In step (5), the catalyst is one or more of hydrochloric acid, concentrated sulfuric acid, formic acid, acetic acid, and trifluoromethanesulfonic acid.

4. The preparation method of MQ silicone resin for medical organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, In step (1), solvent I is one or both of isopropanol and anhydrous ethanol.

5. The method for preparing MQ silicone resin for medical organosilicon pressure-sensitive adhesive according to claim 2, characterized in that, In step (5), component B is a siloxane with the general formula X3SiOSiX3 or a chlorosilane with the general formula Y3SiCl, wherein X is derived from one of the monovalent hydrocarbon groups and Y is derived from one of the monovalent hydrocarbon groups.

6. The preparation method of MQ silicone resin for medical organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, In step (3), solvent II is one or both of toluene and xylene.

7. The preparation method of MQ silicone resin for medical organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, In step (3), the extractant is one or both of toluene and xylene.

8. An MQ silicone resin for medical silicone pressure-sensitive adhesives, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 7.

Images