A silicone polymer, a method of preparation and use thereof in a release agent

Abstract

The application discloses an organic silicon polymer, a preparation method and application of the organic silicon polymer in a release agent. The preparation method comprises the following steps: 1) adding tetramethylcyclotetrasiloxane, glycidyl ether-based cyclotrisiloxane, fluoroalkyl cyclotrisiloxane and octamethylcyclotetrasiloxane into a reaction kettle, and performing ring-opening polymerization under catalysis to obtain an organic silicon intermediate; and 2) adding hexamethyldisiloxane dropwise into the organic silicon intermediate, and performing polymerization under catalysis to obtain the organic silicon polymer. The organic silicon polymer provided by the application has improved reactivity, so that the release agent can be cured faster under low-temperature conditions, the release force is stable after aging, the residual sticking rate is high, the adhesion is good, the high-temperature-resistant substrate can be coated, meanwhile, the coating speed can be improved, and the production efficiency is increased. In addition, the problems, such as silicon dropping caused by the fact that the coating and the substrate surface are not fully contacted due to low temperature and fast curing, are overcome.

Description

Technical Field

[0001] This invention relates to an organosilicon material for release agents, and more particularly to an organosilicon polymer, its preparation method, and its application in release agents. Background Technology

[0002] Silicone release coatings refer to a substrate with a layer of anti-stick film applied to its surface. This allows highly adhesive substances to be easily peeled off. The chemicals that provide this anti-sticking and isolating effect are called release agents or release agents. Silicone release agents are the most widely used due to their advantages such as low toxicity, low surface tension, good wettability with paper, easy formation of a strong film on the paper surface, wide temperature range, and low migration of adhesives. Silicone release agents are mainly used in the production of self-adhesive label paper, pressure-sensitive adhesive paper, composite release paper for decorative materials, release paper for artificial leather, and release paper for medical diagnostic equipment.

[0003] In practical applications of silicone release agents, the following problems need to be addressed: (1) The curing temperature of commonly used release agents is above 120℃, but the heat-sensitive substrates coated cannot be cured at high temperatures and the curing temperature is required to be below 120℃. The decrease in temperature will lead to insufficient curing of the release agent, unstable release force, low residual adhesion rate, and affect the long-term use of the product. (2) As people's demand for high efficiency and energy saving gradually increases, the coating speed of release agents is required to be faster and faster. The common coating speed is about 300m / min. The coating speed of newly built production lines has reached 500m / min and above. However, the length of the drying tunnel has not been increased, which leads to a reduction in the curing time of the release agent, insufficient curing of the release agent, high aging release force, and low residual adhesion rate. (3) With the increase in coating speed, the contact time between the silicone release agent and the substrate is reduced, resulting in insufficient contact between the release agent and the substrate, decreased adhesion, and silicone shedding during long-term storage. (4) As the coating speed increases, the release agent will quickly enter the drying tunnel after coating, which shortens the time for the release agent to wet and spread on the paper, and easily leads to uneven coating of the release agent on the paper.

[0004] To address the above problems, existing technologies have proposed different solutions, such as:

[0005] Chinese patent CN111225960B discloses a low-temperature curing silicone coating. It improves the reactivity of the mixture by extending the main chain length of hydrogen-containing polysiloxane to be greater than that of vinyl polysiloxane, and by increasing the amount of hydrogen-containing polysiloxane added to make the molar ratio of silane groups to vinyl groups greater than 2:1. This allows the coating to cure at low temperatures while maintaining good adhesion. However, excessive silane groups can react with polar groups in the adhesive or form hydrogen bonds during downstream coating applications, resulting in higher aging release forces.

[0006] Chinese patent CN113164647 discloses a low-temperature curing silicone lubricating coating. It improves the catalytic activity of a new catalyst prepared with vinylcyclohexanol, enabling it to cure rapidly at low temperatures. However, due to the low temperature of the substrate, the tightness of the coating on the substrate surface and the bonding between the coating and the substrate decreases, resulting in poor adhesion of the coating to the substrate surface. Long-term storage will lead to a decrease in coating adhesion.

[0007] Chinese patent CN108699339A discloses a method for preparing a low-temperature curing siloxane elastomer. It improves the reactivity of the system by introducing a branched polysiloxane, which enables it to cure at low temperatures and in a short time. However, rapid curing in a short time will result in insufficient density of the coating on the substrate surface and the substrate, which will lead to a decrease in the adhesion of the coating during long-term storage or in high temperature and high humidity environments.

[0008] Chinese patent CN107760098B discloses a method for preparing and applying a low-temperature curing silicone ink. It introduces a high molecular weight methyl vinyl silicone resin, which can react and cure at low temperatures (80-100℃). However, the introduction of the high molecular weight silicone resin will increase the viscosity of the bath system, which will easily lead to uneven coating during the coating process, resulting in unstable release force.

[0009] literature <Demirci A,Yamamoto S,Matsui J,et al.Facile synthesis ofcyclosiloxane-based polymers for hybrid film formation[J].Polymer Chemistry,2015,6(14):2695-2706> The report describes the preparation of intermediates by reacting cyclic siloxanes with small-molecule linear-terminated vinyl polysiloxanes. First, all the vinyl groups are reacted off, and the remaining silanol groups are used to prepare a polymer through internal self-crosslinking. However, because the remaining silanol groups readily react with water to produce easily aggregated silanol groups, the resulting product needs to be stored in an inert gas environment. It is prone to gelation in ordinary air, which cannot meet the needs of daily production.

[0010] In summary, although existing technologies have been extensively studied for low-temperature curing and rapid curing, they can only partially solve the relevant problems and have other performance defects to varying degrees. Therefore, it is necessary to propose a silicone release agent with improved overall performance. Summary of the Invention

[0011] To address the above technical problems, this invention proposes an organosilicon polymer, its preparation method, and its application in release agents.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A method for preparing an organosilicon polymer includes the following steps:

[0014] 1) Tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane are added to a reaction vessel and undergo ring-opening polymerization under catalysis to obtain organosilicon intermediates;

[0015] 2) Hexamethyldisiloxane is added dropwise to an organosilicon intermediate, and a polymerization reaction occurs under catalysis to obtain an organosilicon polymer.

[0016] In some preferred examples, the glycidyl ether-based cyclosiloxane is 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane;

[0017] Preferably, the fluoroalkyl cyclosiloxane is 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and / or 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane.

[0018] In some preferred examples, the mass ratio of tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane is (1-50):(1-100):(1-100):1, preferably (1-25):(1-50):(1-50):1.

[0019] In some preferred examples, step 1) uses at least one of concentrated sulfuric acid, p-toluenesulfonic acid, acidic clay, and solid heteropoly acid as a catalyst. Preferably, the amount of catalyst used in step 1) is 0.1-5% of the total mass of the raw materials tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane.

[0020] In some preferred examples, the reaction conditions in step 1) are stirring at 50-150°C for 2-48 hours, preferably stirring at 80-120°C for 4-24 hours.

[0021] In some preferred examples, in step 2), the amount of hexamethyldisiloxane used is 0.1-10% of the total mass of the organosilicon intermediate, preferably 1-5%.

[0022] In some preferred examples, step 2) uses at least one of concentrated sulfuric acid, p-toluenesulfonic acid, acidic clay, and solid heteropolyacid as a catalyst;

[0023] Preferably, the amount of catalyst used in step 2) is 0.1-5% of the total mass of hexamethyldisiloxane and organosilicon intermediate.

[0024] In some preferred examples, the reaction conditions in step 2) are: a reaction temperature of 50-150℃, preferably 80-120℃, and a holding time of 2-48h, preferably 4-24h.

[0025] The present invention also provides an organosilicon polymer prepared according to the method described above.

[0026] The present invention also provides the application of the organosilicon polymer prepared according to the method described above in organosilicon release agents, especially in solvent-free organosilicon release agents.

[0027] As a feasible example of the solvent-free silicone release agent provided by the present invention, the silicone release agent comprises the following components: vinyl polysiloxane, silicone polymer, catalyst and inhibitor provided above in the present invention;

[0028] Specifically, by weight, the organosilicon isolator contains 100 parts of vinyl polysiloxane, 1-20 parts of organosilicon polymer, 0.5-5 parts of catalyst, and 0.01-1 parts of inhibitor.

[0029] The vinyl polysiloxane, also known as vinyl silicone oil, is a terminal vinyl polysiloxane, a side vinyl polysiloxane, or a terminal-side vinyl polysiloxane, with a suitable product viscosity of 10-1000 cst.

[0030] The catalyst in the organosilicon release agent of the present invention is a group VIII catalyst for rapid formation of cross-linked films under high temperature conditions, preferably a platinum complex or a rhodium complex; more preferably an organically active platinum complex, and even more preferably a Karstedt catalyst, namely 1,3-divinyl-1,1,3,3-tetramethyldisiloxaneplatinum(0).

[0031] The inhibitor in the organosilicon release agent of the present invention is at least one of alkynyl alcohols, enynyl alcohols, organonitrogen compounds, organophosphorus compounds, and acid anhydrides, preferably alkynyl alcohols or acid anhydrides. The alkynyl alcohols are preferably at least one of 3-methyl-1-butyn-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-hexyn-3-ene, and 1-ethynyl-1-cyclohexanol; the acid anhydrides are preferably dimethyl maleate and / or dimethyl transbutenedioate.

[0032] The silicone release agent described in this invention can be applied to various substrates such as paper, polyolefin laminated paper, synthetic resin film, coated paper, and metal foil, and then cured at high temperature to form an anti-stick coating that can be peeled off from the adhesive material on the substrate surface.

[0033] The advantages of this invention over the prior art are as follows:

[0034] (1) The obtained organosilicon polymer introduces glycidyl ether groups and fluorinated alkyl groups into the hydrogen-containing polysiloxane molecular chain, which reduces the arrangement density of hydrogen-containing groups and reduces the steric hindrance when it undergoes addition reaction with vinyl groups, thereby improving its reactivity under the same conditions and enabling the release agent to cure faster at low temperature.

[0035] (2) The silicone release agent prepared from the silicone polymer not only cures more fully at low temperatures and has stable release force after aging, but also has high residual adhesion and good adhesion. It can be used to coat substrates that are not resistant to high temperatures, and can also increase coating speed and production efficiency.

[0036] (3) The introduction of glycidyl ether groups in organosilicon polymers can form an interaction force with polar groups on the substrate surface, which improves the adhesion of the release coating to the substrate and overcomes problems such as silicon drop caused by insufficient contact between the coating and the substrate surface due to low temperature and rapid curing.

[0037] (4) The introduction of fluorinated alkyl groups in organosilicon polymers reduces the molecular surface energy, making it easier to wet the substrate when coating low surface energy substrates and form a uniform coating on the substrate surface. This avoids the problem of uneven coating caused by the short spreading time of the coating on the substrate surface due to the fast coating speed.

[0038] (5) The organosilicon polymer in this invention has high reactivity, which is also conducive to reducing the amount of catalyst used under the same curing performance requirements, thereby reducing the production cost of release agent. Detailed Implementation

[0039] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0040] The main testing methods used in this invention are as follows:

[0041] (1) Determination of curing performance: The silicone release agent was coated onto glassine paper using a coating machine at a speed of 500 m / min and a silicone coating amount of 1 g / m. 2The drying tunnel temperature was 200℃, and the tunnel length was 32m, resulting in release paper products. The curing performance of the release paper products was tested within the range of tunnel length divided by coating speed and time. If there was no matte finish when rubbed by hand, the curing performance was excellent; if there was a matte finish when rubbed by hand, the curing performance was poor.

[0042] (2) Determination of release force: A force sensor-type peel force tester was used. The tensile speed was 30 m / min, the tensile distance was 100 mm, and the sample size was 150 × 25 mm. Test method: The silicone release agent was coated onto glassine paper using a coating machine at a speed of 500 m / min, a drying tunnel temperature of 200℃, and a drying tunnel length of 32 m to obtain the release paper product. The silicone coating amount was 1 g / m. 2 Apply commercially available pressure-sensitive Tesa 7475 tape to the surface of the offset paper coated with a release agent curing film, taking care not to create air gaps inside (roll back and forth twice with a 2kg roller), and then perform a 180° peel test.

[0043] (3) Determination of release force under aging: A force sensor-type peel force tester was used, with a tensile speed of 30 m / min, a tensile distance of 100 mm, and a sample size of 1500 × 25 mm. Test method: Commercially available pressure-sensitive Tesa7475 tape was pasted onto the surface of the offset paper coated with a release agent curing film, taking care not to create air gaps inside (using a 2 kg pressure roller to roll back and forth twice), and aged at 70℃ for 20 h, and then a 180° peel test was performed.

[0044] (4) Determination of residual adhesion rate: The residual adhesion rate is determined by the reduction in adhesive force caused by silicone migration. Commercially available Nitto 31B tape is pasted onto the surface of offset paper coated with a release agent curing film, taking care not to create air gaps inside (rolling back and forth twice with a 2kg pressure roller), and then aged at 70℃ for 20h. Then, the Nitto 31B tape is peeled off and transferred to PET, and rolled back and forth twice with a 2kg pressure. After 1h, a 180° peel test is performed, and the force measured is F1. At the same time, Nitto 31B tape is pasted onto PET, and rolled back and forth twice with a 2kg pressure. After 1h, a 180° peel test is performed, and the force measured is F2. The value obtained by F1 / F2*100% is the residual adhesion rate.

[0045] (5) Adhesion test: After coating, the substrate is placed in a high temperature and high humidity chamber (65℃ / 90%) for different aging times. The substrate is then removed and rubbed by hand to test whether there is any silicone removal. If the silicone can be removed by hand within three days of aging, the performance is poor. If no silicone is removed after 3 days or more of aging, the performance is excellent.

[0046] The main raw material information in the following embodiments of the present invention is as follows:

[0047] Tetramethylcyclotetrasiloxane: Shandong Maofa Chemical Co., Ltd.

[0048] Karstedt catalyst: platinum metal content 5000 ppm; Heraeus catalyst:

[0049] Octamethylcyclotetrasiloxane: Shandong Qiyun Chemical Co., Ltd.

[0050] Chloroplatinic acid: Aladdin;

[0051] Chloroauric acid: Aladdin;

[0052] Glycidyl etheroxypropylcyclotetrasiloxane: Jiehua New Materials;

[0053] 1,3,5-Trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane: Bailingwei Technology;

[0054] Concentrated sulfuric acid: Yangzhou Huafu Chemical Co., Ltd.

[0055]

Example 1

[0056] 100g of octamethylcyclotetrasiloxane, 300g of tetramethylcyclotetrasiloxane, 1000g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane and 2000g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane were added sequentially to a flask and stirred at 100 rpm. The mixture was heated to 120°C, and 34g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a rate of 5ml / min. The mixture was kept at this temperature and stirred for 20 hours to obtain an organosilicon intermediate. 5g of hexamethyldisiloxane was added dropwise to 500g of the organosilicon intermediate, and the mixture was kept at 120°C for 10 hours. The mixture was then cooled to room temperature, washed with water, and dried to obtain an organosilicon polymer.

[0057]

Example 2

[0058] 10g of octamethylcyclotetrasiloxane, 500g of tetramethylcyclotetrasiloxane, 1000g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane and 1000g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane were added sequentially to a flask and stirred at 100 rpm. The mixture was heated to 150°C, and 2.6g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a rate of 5ml / min. The mixture was kept at this temperature and stirred for 48 hours to obtain an organosilicon intermediate. 0.5g of hexamethyldisiloxane was added dropwise to 500g of the organosilicon intermediate, and the mixture was kept at 150°C for 12 hours. The mixture was then cooled to room temperature, washed with water, and dried to obtain an organosilicon polymer.

[0059]

Example 3

[0060] 100g of octamethylcyclotetrasiloxane, 100g of tetramethylcyclotetrasiloxane, 100g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane and 100g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane were added to a flask and stirred at 100 rpm. The mixture was heated to 50°C, and 20g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a rate of 5ml / min. The mixture was kept at this temperature and stirred for 2 hours to obtain an organosilicon intermediate. 10g of hexamethyldisiloxane was added dropwise to 100g of the organosilicon intermediate, and the mixture was kept at 50°C for 2 hours. The mixture was then cooled to room temperature, washed with water, and dried to obtain an organosilicon polymer.

[0061]

Example 4

[0062] 100g of octamethylcyclotetrasiloxane, 1000g of tetramethylcyclotetrasiloxane, 500g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane and 100g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane were added to a flask and stirred at 100 rpm. The mixture was heated to 100°C, and 17g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a rate of 5ml / min. The mixture was kept at this temperature and stirred for 24 hours to obtain an organosilicon intermediate. 10g of hexamethyldisiloxane was added dropwise to 1000g of the organosilicon intermediate, and the mixture was kept at 80°C for 24 hours. The mixture was then cooled to room temperature, washed with water, and dried to obtain an organosilicon polymer.

[0063]

Application Example

[0064] Using the organosilicon polymers prepared in each embodiment as raw materials, organosilicon release agents were prepared according to the following formulations, and then the performance tests in Table 1 were performed.

[0065] 50g of organosilicon polymer, 500g of vinyl polysiloxane (brand name VS200, viscosity 200cst, Shandong Shengyou New Material Co., Ltd.), 1g of 1-ethynyl-1-cyclohexanol, and 2g of Karstedt catalyst.

[0066] In addition, using hydrogen-containing polysiloxane (brand name 1107, viscosity 20 cst, Dow Chemical) as a comparative example, an organosilicon release agent was prepared according to the above formulation. The performance test results of release agents prepared from different organosilicon polymers are compared below:

[0067] Table 1. Performance Test Results

[0068]

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an organosilicon polymer, characterized in that, Includes the following steps: 1) Tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane are added to a reactor and undergo ring-opening polymerization under catalysis to obtain an organosilicon intermediate; the mass ratio of tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane is (1-50):(1-100):(1-100):

1. 2) Hexamethyldisiloxane is added dropwise to an organosilicon intermediate, and a polymerization reaction occurs under catalysis to obtain an organosilicon polymer.

2. The method for preparing the organosilicon polymer according to claim 1, characterized in that, The glycidyl ether-based cyclosiloxane is 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane.

3. The method for preparing the organosilicon polymer according to claim 2, characterized in that, The fluoroalkyl cyclosiloxane is 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and / or 2,4,6,8-tetramethyl-2,4,6,8-tetra(3,3,3-trifluoropropyl)cyclotetrasiloxane.

4. The method for preparing the organosilicon polymer according to claim 1, characterized in that, The mass ratio of tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane is (1-25):(1-50):(1-50):

1.

5. The method for preparing the organosilicon polymer according to any one of claims 1-4, characterized in that, Step 1) Use at least one of concentrated sulfuric acid, p-toluenesulfonic acid, acidic clay, or solid heteropoly acid as a catalyst.

6. The method for preparing the organosilicon polymer according to claim 5, characterized in that, Step 1) The amount of catalyst used is 0.1-5% of the total mass of the raw materials tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane, and octamethylcyclotetrasiloxane.

7. The method for preparing the organosilicon polymer according to any one of claims 1-4, characterized in that, The reaction conditions in step 1) are: stirring at 50-150℃ for 2-48 hours.

8. The method for preparing the organosilicon polymer according to claim 7, characterized in that, The reaction conditions in step 1) are to stir the reaction at 80-120℃ for 4-24 hours.

9. The method for preparing the organosilicon polymer according to any one of claims 1-4, characterized in that, In step 2), the amount of hexamethyldisiloxane used is 0.1-10% of the total mass of the organosilicon intermediate.

10. The method for preparing the organosilicon polymer according to claim 9, characterized in that, In step 2), the amount of hexamethyldisiloxane used is 1-5% of the total mass of the organosilicon intermediate.

11. The method for preparing the organosilicon polymer according to any one of claims 1-4, characterized in that, Step 2) Use at least one of concentrated sulfuric acid, p-toluenesulfonic acid, acidic clay, and solid heteropoly acid as a catalyst.

12. The method for preparing the organosilicon polymer according to claim 11, characterized in that, Step 2) The amount of catalyst used is 0.1-5% of the total mass of hexamethyldisiloxane and organosilicon intermediate.

13. The method for preparing the organosilicon polymer according to any one of claims 1-4, characterized in that, The reaction conditions in step 2) are: reaction temperature of 50-150℃, and holding temperature for 2-48 hours.

14. The method for preparing the organosilicon polymer according to claim 13, characterized in that, The reaction conditions in step 2) are: reaction temperature of 80-120℃, and holding temperature for 4-24 hours.

15. An organosilicon polymer prepared by the method according to any one of claims 1-14.

16. The use of an organosilicon polymer prepared by the method according to any one of claims 1-14 in an organosilicon release agent.

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