Organosilicon polymer, preparation method and application of organosilicon polymer in release agent

Abstract

The invention discloses an organosilicon polymer, a preparation method and application of the organosilicon polymer in a release agent. The preparation method comprises the following steps: 1) adding tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane and octamethylcyclotetrasiloxane into a reaction kettle, and carrying out ring-opening polymerization reaction under the catalytic action to obtain an organic silicon intermediate; and 2) dropwise adding hexamethyldisiloxane into the organic silicon intermediate, and carrying out polymerization reaction under the catalytic action to obtain the organic silicon polymer. The organic silicon polymer provided by the invention has improved reaction activity, so that the release agent can be more quickly cured under a low-temperature condition, the aging release force is stable, the residual adhesion rate is high, the adhesiveness is good, a base material which is not resistant to high temperature can be coated, the coating speed can be increased, and the production efficiency can be improved. In addition, the problems of silicon falling and the like caused by insufficient contact between the coating and the surface of the base material due to low temperature and rapid curing are solved.

Description

Technical Field

[0001] The invention relates to an organosilicon material for a release agent, and in particular to an organosilicon polymer, a preparation method and application thereof in a release agent. Background Art

[0002] Silicone release coating refers to a substrate with a layer of anti-adhesive film on the surface, which can easily peel off highly adhesive materials. The chemical that plays an anti-adhesive and isolating role is called an isolating agent or release agent. Silicone release agents are the most widely used because of their low toxicity, low surface tension, good wettability with paper, easy to form a firm film on the surface of paper, wide temperature application range, and low migration to 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, artificial leather release paper, and release paper for medical diagnostic equipment.

[0003] In the practical application of silicone release agents, the following problems need to be solved: (1) The curing temperature of the commonly used release agents is above 120°C, but some heat-sensitive substrates cannot be cured at high temperatures. The curing temperature is required to be within 120°C. The reduction in temperature will lead to insufficient curing of the release agent, unstable release force, and low residual adhesion rate, which will 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 the release agent is required to be faster and faster. The common coating speed is about 300m / min. The coating speed of the newly built production line has reached 500m / min and above, but the length of the drying tunnel has not been extended, 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) As the coating speed increases, the contact time between the silicone release agent and the substrate is reduced, resulting in insufficient contact between the release agent and the substrate, reduced adhesion, and the problem of silicon falling during long-term storage. (4) As the coating speed increases, the release agent will quickly enter the drying tunnel after coating, thereby shortening the time for the release agent to wet and spread on the paper, which can easily lead to the problem of uneven coating of the release agent on the paper.

[0004] In order to solve the above problems, the prior art has proposed different solutions, such as:

[0005] Chinese patent CN111225960B discloses a low-temperature curing silicone coating, which increases the reactivity of the mixture by extending the main chain length of hydrogen-containing polysiloxane to make it greater than the main chain length of vinyl polysiloxane, and by increasing the amount of hydrogen-containing polysiloxane added so that the molar ratio of silicon hydrogen groups to vinyl groups is greater than 2:1, so that it can be cured at low temperatures and has good adhesion. However, excessive silicon hydrogen groups will react with polar groups in the glue or form hydrogen bonds and other interactions during downstream coating applications, resulting in a high aging release force.

[0006] Chinese patent CN113164647 discloses a low-temperature curing silicone lubricating coating, which uses vinyl cyclohexanol to prepare a new catalyst to improve its catalytic activity so that it can cure quickly at low temperatures. However, due to the low temperature of the substrate, the tightness of the coating applied to the substrate surface and the substrate bonding will decrease, and the adhesion of the coating to the substrate surface is not good enough. Long-term storage will lead to a problem of decreased adhesion of the coating.

[0007] Chinese patent CN108699339A discloses a method for preparing a low-temperature curing silicone elastomer, which improves the reaction activity of the system by introducing branched polysiloxane, so that it can be cured at low temperature and in a short time. However, rapid curing in a short time will result in insufficient density of the coating applied on the surface of the substrate and the substrate, which will lead to a decrease in the adhesion of the coating during long-term storage or in a high temperature and high humidity environment.

[0008] Chinese patent CN107760098B discloses a method for preparing and applying a low-temperature curing silicone ink, which can react and cure at low temperatures (80-100°C) by introducing a high molecular weight methyl vinyl silicone resin. However, the introduction of the high molecular weight silicone resin will lead to an increase in the viscosity of the bath system, which can easily lead to uneven coating during the coating process, thereby causing 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> It is reported that an intermediate is prepared by reacting cyclic siloxane and small molecule linear terminal vinyl polysiloxane, in which all the vinyl groups are reacted first, and the remaining silicon hydrogen groups are used to produce a high molecular polymer through internal self-crosslinking reaction; because the remaining silicon hydrogen groups easily react with water to produce easily condensed silanol groups, the obtained product needs to be stored in an inert gas and is easy to produce gel in an ordinary air environment, which cannot meet the use needs in daily production.

[0010] In summary, although a lot of research has been done on the known technologies for low temperature curing and rapid curing, they can only partially solve the related problems and have more or less defects in other performance aspects. Therefore, it is necessary to propose a silicone release agent with improved comprehensive performance. Summary of the invention

[0011] In order to solve the above technical problems, the present invention provides an organosilicon polymer, a preparation method and application thereof in a release agent.

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

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

[0014] 1) adding tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane and octamethylcyclotetrasiloxane into a reaction kettle, and performing a ring-opening polymerization reaction under the action of a catalyst to obtain an organosilicon intermediate;

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

[0016] In some preferred examples, the glycidyl ether cyclosiloxane is 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl 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-tetrakis(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 heteropolyacid as a catalyst. Preferably, the amount of the 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 the reaction at 50-150° C. for 2-48 h, preferably stirring the reaction at 80-120° C. for 4-24 h.

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

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

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

[0024] In some preferred examples, the reaction conditions in step 2) are: reaction temperature is 50-150°C, preferably 80-120°C, and the reaction is kept warm for 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 an application of the organosilicon polymer prepared according to the method described above in an organosilicon release agent, especially in a solvent-free organosilicon release agent.

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

[0028] Specifically, the organosilicon release agent comprises, by weight, 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 is also called vinyl silicone oil, which is terminal vinyl polysiloxane, side vinyl polysiloxane or terminal side vinyl polysiloxane, and the suitable product viscosity is 10-1000cst.

[0030] The catalyst in the silicone release agent of the present invention is a Group VIII catalyst for rapidly forming a cross-linked film under high temperature conditions, preferably a platinum complex or a rhodium complex; more preferably an organically active platinum complex, and further preferably a Karstedt catalyst, i.e. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (0).

[0031] The inhibitor in the silicone release agent of the present invention is at least one of acetylenic alcohol compounds, ene acetylenic compounds, organic nitrogen compounds, organic phosphorus compounds and acid anhydride compounds, preferably acetylenic alcohol compounds and acid anhydride compounds. The acetylenic alcohol compound is preferably at least one of 3-methyl-1-butynol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-hexyn-3-ene, and 1-ethynyl-1-cyclohexanol; the acid anhydride compound is preferably dimethyl maleate and / or dimethyl fumarate.

[0032] The silicone release agent of the present invention can be coated on 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-sticking coating that can be peeled off from sticky substances on the surface of the substrate.

[0033] The beneficial effects of the present invention compared to the prior art are:

[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 the hydrogen-containing groups and reduces the steric hindrance when it undergoes addition reaction with the vinyl group, thereby improving its reaction activity under the same conditions and allowing the release agent to cure faster under low temperature conditions.

[0035] (2) The silicone release agent prepared from the silicone polymer not only has more complete low-temperature curing and stable aging release force, but also has a high residual bonding rate and good adhesion. It can be coated on substrates that are not resistant to high temperatures, and at the same time can increase the coating speed and increase production efficiency.

[0036] (3) The introduction of glycidyl ether groups in silicone polymers can form forces with polar groups on the surface of the substrate, thereby improving the adhesion of the release coating to the substrate and overcoming problems such as silicon peeling 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 silicone polymers reduces the molecular surface energy, making it easier to wet the substrate when coating low surface energy substrates and easier to form a uniform coating on the substrate surface, thereby avoiding the problem of uneven coating caused by fast coating speed and short coating time on the substrate surface.

[0038] (5) The organic silicon polymer in the present invention has high reactivity, which is also beneficial to reduce the amount of catalyst used under the same curing performance requirements, thereby reducing the production cost of the release agent. DETAILED DESCRIPTION

[0039] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0040] The main test methods used in the present invention are as follows:

[0041] (1) Determination of curing performance: The silicone release agent was applied to glassine paper by a coating machine at a coating speed of 500 m / min and a silicone coating amount of 1 g / m 2, drying tunnel temperature 200℃, drying tunnel length 32m, to obtain release paper products. Test the curing performance of release paper products within the time range of drying tunnel length divided by coating speed. If there is no matting phenomenon when rubbing by hand, it means the curing performance is excellent. If there is matting phenomenon when rubbing by hand, it means the curing performance is poor.

[0042] (2) Determination of release force: A force sensor type peeling force tester was used, with a tensile speed of 30 m / min, a tensile distance of 100 mm, and a sample size of 150×25 mm. Test method: The silicone release agent was applied to glassine paper through a coating machine, with a coating speed of 500 m / min, a drying oven temperature of 200°C, and a drying oven length of 32 m to obtain a release paper product, and the silicone coating amount was 1 g / m 2 The commercially available pressure-sensitive Tesa7475 tape was pasted onto the surface of the offset paper coated with the release agent cured film, taking care not to create air gaps inside (rolled back and forth twice with a 2kg roller), and then a 180° peeling test was performed.

[0043] (3) Determination of aging release force: Use a force sensor type peeling force tester, with a tensile speed of 30m / min, a tensile distance of 100mm, and a sample size of 1500×25mm. Test method: Paste the commercially available pressure-sensitive Tesa7475 tape to the surface of the offset paper coated with the release agent cured film, taking care not to create air gaps inside (roll back and forth twice with a 2kg roller), place it at 70℃ for aging for 20h, and then perform a 180° peeling test.

[0044] (4) Determination of residual adhesion: The residual adhesion is a measure of the reduction in adhesion caused by silicone migration. The commercially available Nitto 31B tape was pasted to the surface of the offset paper coated with a release agent cured film, and it was noted that no air gap was generated inside (rolled back and forth twice with a 2kg roller), and then aged at 70°C for 20 hours. The Nitto 31B tape was then peeled off and transferred to PET. It was rolled back and forth twice with a pressure of 2kg. After 1 hour, a 180° peeling test was performed. The force measured was F1. At the same time, the Nitto 31B tape was pasted to PET, rolled back and forth twice with a pressure of 2kg. After 1 hour, a 180° peeling test was performed. The force measured was F2. The value obtained by F1 / F2*100% was the residual adhesion.

[0045] (5) Adhesion test: The coated substrate was placed in a high temperature and high humidity chamber (65°C / 90%) for different aging times, and then taken out and rubbed by hand to test whether the silicon had fallen off. If the silicon had fallen off by hand within three days of aging, the performance was poor, and if the silicon had not fallen off after aging for 3 days or more, the performance was excellent.

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

[0047] Tetramethylcyclotetrasiloxane: Shandong Maofa Chemical;

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

[0049] Octamethylcyclotetrasiloxane: Shandong Qiyun Chemical;

[0050] Chloroplatinic acid: Aladdin;

[0051] Chloroauric acid: Aladdin;

[0052] Glycidyl ether oxypropyl cyclotetrasiloxane: Jiehua New Materials;

[0053] 1,3,5-Trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane: J&K Technologies;

[0054] Concentrated sulfuric acid: Yangzhou Huafu Chemical.

[0055] [Example 1]

[0056] 100g of octamethylcyclotetrasiloxane, 300g of tetramethylcyclotetrasiloxane, 1000g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether)cyclotetrasiloxane and 2000g of 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane were added to a flask in sequence, stirring was started, the speed was 100rpm, and the mixture was heated to 120°C. 34g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a dropping rate of 5ml / min, and the mixture was stirred for 20h to obtain an organosilicon intermediate. 5g of hexamethyldisiloxane was added dropwise to 500g of the organosilicon intermediate, the mixture was reacted at 120°C for 10h, the mixture was 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(propyl glycidyl ether)cyclotetrasiloxane and 1000g of 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane were added to a flask in sequence, stirring was started, the speed was 100rpm, and the mixture was heated to 150°C. 2.6g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a dropping rate of 5ml / min, and the mixture was stirred for 48h to obtain an organosilicon intermediate. 0.5g of hexamethyldisiloxane was added dropwise to 500g of the organosilicon intermediate, the mixture was reacted at 150°C for 12h, the temperature was lowered to room temperature, the mixture was washed with water, and the mixture was dried to obtain an organosilicon polymer.

[0059] [Example 3]

[0060] 100 g of octamethylcyclotetrasiloxane, 100 g of tetramethylcyclotetrasiloxane, 100 g of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether)cyclotetrasiloxane and 100 g of 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane were added to a flask in sequence, stirring was started, the speed was 100 rpm, and the mixture was heated to 50° C. 20 g of concentrated sulfuric acid (98 wt%) was added dropwise to the flask at a dropping rate of 5 ml / min, and the mixture was stirred for 2 h to obtain an organosilicon intermediate; 10 g of hexamethyldisiloxane was added dropwise to 100 g of the organosilicon intermediate, the mixture was reacted at 50° C. for 2 h, the mixture was 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(propyl glycidyl ether)cyclotetrasiloxane and 100g of 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane were added to a flask in sequence, stirring was started, the speed was 100rpm, and the mixture was heated to 100°C. 17g of concentrated sulfuric acid (98wt%) was added dropwise to the flask at a dropping rate of 5ml / min, and the mixture was stirred for 24h to obtain an organosilicon intermediate. 10g of hexamethyldisiloxane was added dropwise to 1000g of the organosilicon intermediate, the mixture was reacted at 80°C for 24h, the mixture was cooled to room temperature, washed with water, and dried to obtain an organosilicon polymer.

[0063]

Application examples

[0064] The organosilicon polymers prepared in the examples were used as raw materials to prepare organosilicon release agents according to the following formulas, and then the performance tests shown in Table 1 were performed.

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

[0066] In addition, hydrogenated polysiloxane (brand 1107, viscosity 20 cst, Dow Chemical) was used as a comparative example to prepare a silicone release agent according to the above formula. The performance test results of release agents prepared from different silicone polymers are compared as follows:

[0067] Table 1. Performance test results

[0068]

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an organosilicon polymer, characterized in that: The following steps are involved: 1) adding tetramethylcyclotetrasiloxane, glycidyl ether cyclosiloxane, fluoroalkyl cyclosiloxane and octamethylcyclotetrasiloxane into a reaction kettle, and performing a ring-opening polymerization reaction under the action of a catalyst to obtain an organosilicon intermediate; 2) Hexamethyldisiloxane is added dropwise to the organosilicon intermediate, and a polymerization reaction occurs under the action of a catalyst to obtain an organosilicon polymer.

2. The method for preparing an organosilicon polymer according to claim 1, characterized in that: The glycidyl ether cyclosiloxane is 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether) cyclotetrasiloxane; 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-tetrakis(3,3,3-trifluoropropyl)cyclotetrasiloxane.

3. The method for preparing an organosilicon polymer according to claim 1, characterized in that: 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.

4. The method for preparing an organosilicon polymer according to any one of claims 1 to 3, characterized in that: In step 1), at least one of concentrated sulfuric acid, p-toluenesulfonic acid, acidic clay and solid heteropolyacid is used as a catalyst. Preferably, the amount of the 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.

5. The method for preparing an organosilicon polymer according to any one of claims 1 to 4, characterized in that: The reaction conditions in step 1) are stirring at 50-150° C. for 2-48 h, preferably stirring at 80-120° C. for 4-24 h.

6. The method for preparing an organosilicon polymer according to any one of claims 1 to 5, characterized in that: In step 2), the amount of hexamethyldisiloxane used is 0.1-10%, preferably 1-5%, of the total mass of the organosilicon intermediate.

7. The method for preparing an organosilicon polymer according to any one of claims 1 to 6, characterized in that: Step 2) using 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 2) is 0.1-5% of the total mass of hexamethyldisiloxane and the organosilicon intermediate.

8. The method for preparing an organosilicon polymer according to any one of claims 1 to 7, characterized in that: The reaction conditions in step 2) are: reaction temperature is 50-150° C., preferably 80-120° C., and the reaction is kept warm for 2-48 hours, preferably 4-24 hours.

9. An organosilicon polymer obtained by the method according to any one of claims 1 to 8.

10. Use of the organosilicon polymer prepared by the method according to any one of claims 1 to 8 in an organosilicon release agent.

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