A release coating and methods of use and processing thereof

Abstract

The present application relates to a kind of release coating and its use and processing method, belong to investment casting, injection molding and rubber forming technical field, the integrity and precision of the formed piece in prior art are low, easy to be corroded, the forming die is harmed to environment and worker health, easy to be remained on the surface of forming material, need to be supplemented before forming, extend process and work time and intensify harm.Pressing is separated from the forming material after being covered with the release coating disclosed in the present application, and the pulling force and shear force required for pressing is reduced, and the release coating is firmly combined with the pressing, and the adhesive layer is further set to strengthen the combination of the two, the size of the formed piece is accurate, the surface roughness is low, and the release can be repeated.Production cost is saved by simplifying process and work time;The release coating does not corrode the pressing, and no toxic substances are released during pressing, and there is no residue on the surface of the pressed part after demolding, so there is no need to supplement before casting, which is friendly to worker health and environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of investment casting, injection molding and rubber forming technology, and particularly relates to a release coating and a use and processing method thereof. BACKGROUND

[0002] In the production industry, many products with fixed shapes are obtained by casting in a mold to obtain stable shape and size. The raw materials of such products mainly include plastics, composite materials and metal materials, and the mold is generally made of metal materials such as aluminum, copper and stainless steel. In the material forming process, in order to prevent the adhesion of elastic materials such as rubber and plastic and other materials on the surface of the mold during processing, a release agent is often sprayed between the mold and the organic polymer material or other products, so that the finished product prototype can be quickly and cleanly separated from the mold. There are many types of release agents, and the silicon oil release agent mainly using organosiloxane and siloxane compounds as the main material is mainly used for plastic and rubber products. In addition, investment casting produces precision parts by preparing a wax mold of the required casting, forming a refractory shell by lost wax method, and finally pouring metal liquid. The main component of the wax mold raw material is straight-chain alkane, and a silicon oil release agent is also selected in industrial production to help the wax mold and the metal mold to be separated smoothly. The silicon oil release agent can form a micron-level thick isolation layer on the surface of the mold, effectively reducing the adhesion between the formed material and the mold, so that the product can be smoothly and completely separated from the mold. The molecules of the release agent form a film layer on the surface of the metal mold due to adsorption, but the weak adsorption force makes the isolation layer easily damaged during the demolding process, part of which remains on the mold, and the other part is transferred to the stripping surface of the formed material. In actual production process, the release agent needs to be sprayed again to form a uniform isolation layer before re-forming, and the formed part also needs to be cleaned with an organic solvent to avoid pollution, which not only prolongs the process and working hours, but also increases the difficulty of wastewater treatment. In addition, the release agent can corrode the mold material, and the release agent contains harmful substances such as halogenated hydrocarbons and n-hexane, which are harmful to workers' health and the environment when sprayed into the air.

[0003] In summary, the existing technology has the following two problems: (1) when no release agent is used, rubber, plastic and wax are easy to adhere to the surface of the mold, which reduces the integrity and precision of the formed part, and (2) when the release agent is used, the release agent is easy to corrode the mold, volatile to harm the environment and workers' health, easy to remain on the surface of the formed material and need to be cleaned with an organic solvent, which needs to be treated wastewater, and needs to be sprayed again before re-forming, which prolongs the process and working hours and intensifies the harm to the environment and workers' health. SUMMARY

[0004] In view of the above problems, the present application provides a release coating and its use and processing method, which solves the two problems existing in the prior art: (1) when no release agent is used, rubber, plastic and wax are easy to adhere to the surface of the mold, thereby reducing the integrity and precision of the molded part; (2) when a release agent is used, the release agent is easy to corrode the mold, volatile, harm the environment and the health of workers, easy to remain on the surface of the molded material and need to be cleaned with an organic solvent, thereby needing to treat wastewater, and needing to be re-sprayed before the next molding, thereby prolonging the process and working hours and intensifying the harm to the environment and the health of workers.

[0005] The present application provides a release coating, which is prepared from raw materials in the following mass percentage: 1-10% of a first raw material and 90-99% of a second raw material; wherein the first raw material is a group-modified silicone oil, and the second raw material is a resin with O active groups; the first raw material and the second raw material are pre-polymerized to form the release coating through a film forming process.

[0006] Further, the mass percentage of the first raw material is 4-7%.

[0007] Further, the second raw material is an oxygen-containing polyester resin or an epoxy resin.

[0008] Further, the first raw material is an amino-terminated silicone oil or an epoxy-modified silicone oil.

[0009] Further, the present application also provides a mold, the inner cavity surface of which is provided with the above-mentioned release coating.

[0010] The present application also provides a use method of the above-mentioned release coating, in which the above-mentioned release coating is provided on the inner cavity surface of a mold.

[0011] Further, an adhesive layer is provided between the inner cavity surface of the mold and the release coating, which is used to improve the bonding force between the release coating and the inner cavity surface of the mold.

[0012] Further, the adhesive layer is a cured product of at least one adhesive selected from polyurethane adhesive, epoxy adhesive, phenolic adhesive and silicone adhesive, and the corresponding adhesive is selected according to the second raw material.

[0013] Further, the thickness of the release coating is less than 20 μm.

[0014] The present application also provides a processing method of the above-mentioned release coating, which comprises the following steps:

[0015] cleaning and drying the inner cavity surface of the mold;

[0016] mixing the first raw material and the second raw material at room temperature and pre-polymerizing by fully stirring;

[0017] The prepolymer is deposited on the inner cavity surface of the mold by a film forming process, and the release coating is formed after the second raw material is completely cured at room temperature for 24 hours.

[0018] Compared with the prior art, the present application has at least the following beneficial effects:

[0019] (1) Compared with not using a release agent or the release coating disclosed in the present application, the pulling force and shear force required for the mold material to separate from the rubber, plastic and wax mold after the release coating disclosed in the present application is set is reduced, and the release coating is firmly combined with the mold metal, and the adhesive layer further strengthens the combination of the release coating and the mold material, so that repeated demolding can be realized while ensuring the dimensional accuracy and surface roughness of the molded part.

[0020] (2) Compared with using a release agent, the present application simplifies the process and working hours of the investment casting, injection molding and rubber molding process, saves production costs; the release coating does not corrode the mold, and does not release toxic substances during the pressing process, and there is no coating residue on the surface of the molded part after demolding, so that repeated demolding can be realized, and there is no need to perform re-spraying before re-molding, which is friendly to workers and the environment. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings are for the purpose of illustrating preferred embodiments of the present application and are not to be construed as limiting the same thereto.

[0022] Figure 1 Functional group action diagram for the release coating in the embodiments of the present application;

[0023] Figure 2 Cross-sectional view of the release coating in the embodiments of the present application;

[0024] Figure 3 Cross-sectional view of the release coating and the adhesive layer in the embodiments of the present application;

[0025] Figure 4 Process flow chart of the release coating in the embodiments of the present application;

[0026] Figure 5 Test diagram of the contact angle of the medium temperature wax liquid in the comparative example 1 of the present application;

[0027] Figure 6 Test diagram of the contact angle of the rubber in the comparative example 2 of the present application;

[0028] Figure 7 Test diagram of the contact angle of the polypropylene plastic in the comparative example 3 of the present application;

[0029] Figure 8 Test diagram of the contact angle of the medium temperature wax liquid in the example 3 of the present application;

[0030] Figure 9Figure for testing contact angle of the mold release coating of the present application after 10 times of demolding with a medium temperature wax liquid;

[0031] Figure 10 Figure for testing contact angle of the mold release coating of the present application after 10 times of demolding with a medium temperature wax liquid; DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present application more clearly understood, the present application will be further described below with reference to the drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. In addition, the present application can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0033] The mold release agent is a spraying material used during casting, which is sprayed on the surface of the mold to make the surface of the mold material have very low surface energy, and at the same time form a certain thickness of isolation layer on the surface of the mold.

[0034] In actual production, there are many problems in the use of mold release agent: the traditional silicone oil mold release agent has great harm to the health of workers and the environment, and there is a hidden danger of burning and explosion during use. In addition, the use of mold release agent can also cause corrosion to the molding material, affecting the precision of the size of the parts. Moreover, after the molded parts are removed, they need to be cleaned with organic solvents, which increases the process and working hours, and further affects the parts and the environment. Although there are currently non-ionic, non-toxic and easy-to-clean mold release agents, such mold release agents are water-soluble and may cause corrosion to metal molds during use. In addition, the use of mold release agent inevitably requires repeated spraying of mold release agent and cleaning of molded parts during each pressing process, making the casting process more complicated and affecting production efficiency.

[0035] Therefore, the embodiments of the present application provide a mold release coating and its use and processing method, which replace the silicone oil mold release agent, help the molded parts to demold by arranging the mold release coating on the inner cavity surface of the pressing type, and the coating can be repeatedly demolded after being arranged, thereby omitting the steps of repeatedly spraying and cleaning the mold release agent in the pressing process, saving production cost, minimizing harm to the health of workers and the environment, and responding to the call for green production and cost reduction and efficiency improvement.

[0036] Embodiment 1

[0037] In one specific embodiment of the present application, a mold release coating and its use and processing method are disclosed, which are prepared from a first raw material and a second raw material, wherein the first raw material is a group-modified silicone oil, and the second raw material is a resin with O active groups.

[0038] Silicone oil is a kind of mineral oil, and group-modified silicone oil refers to a kind of silicone oil that changes its molecular structure and properties by introducing different organic groups into the silicone oil molecules. Group-modified silicone oil has a wide range of applications in different fields due to its diverse molecular structure and adjustable properties.

[0039] It is worth noting that the existing technology uses release agents by spraying, which has a greater impact on air and worker health. However, the silicone oil in the release coating of the present scheme is pre-polymerized with the resin and stably exists, without volatility, thus being environmentally friendly. Group-modified silicone oil is selected to have functional groups that can react with the resin.

[0040] Common group-modified silicone oils include: (1) alkyl-modified silicone oil: introducing alkyl groups into the silicone oil molecules can increase their lipophilicity and lubricity; (2) alkenyl-modified silicone oil: introducing alkenyl groups into the silicone oil molecules can increase their reactivity and film-forming properties; (3) siloxane-modified silicone oil: introducing siloxane groups into the silicone oil molecules can increase their high-temperature resistance and oxidation resistance; (4) silane-modified silicone oil: introducing silane groups into the silicone oil molecules can increase their compatibility and adhesion with inorganic materials; (5) hydroxyl-modified silicone oil: introducing hydroxyl groups into the silicone oil molecules can increase their hydrophilicity and biocompatibility.

[0041] O-active groups refer to chemical groups containing oxygen atoms in the molecule, such as: hydroxyl (-OH), carbonyl (C=O), ester (-COO-), carboxyl (-COOH), thiol (-SH), peroxide (-O-O-), etc. Resins with O-active groups are a type of resin with special oxidative groups that can react with other substances to form new compounds. The O-active groups in these resins give the resin many special properties and uses, such as hydrophilicity, biocompatibility, adhesion, etc., and are widely used in various fields.

[0042] There are many types of resins with O-active groups, including: (1) hydroxyl resins: hydroxyl resins refer to resins containing hydroxyl (-OH) groups, such as phenolic resins, epoxy resins, etc.; (2) carboxyl resins: carboxyl resins refer to resins containing carboxyl (-COOH) groups, such as polyester resins, polyamide resins, etc.; (3) ester resins: ester resins refer to resins containing ester (-COO-) groups, such as polyvinyl acetate, polyacrylate, etc.; (4) siloxane resins: siloxane resins refer to resins containing siloxane groups, such as silicone rubber, silane coupling agent, etc.; (5) thiol resins: thiol resins refer to resins containing thiol (-SH) groups, such as vulcanized rubber, thiol-modified polymers, etc.

[0043] In the embodiment, the group-modified silicone oil as the first raw material and the resin with O-active group as the second raw material are mixed, the O-active group is pre-polymerized with the silicone oil as an initiator, the film is formed with the solvent in the resin evaporated, the silicone oil is solidified to form a stable isolation effect on the surface of the coating, and the release coating is obtained.

[0044] For example, the -OH, -NH2, etc. on the end group or side chain of the first raw material reacts with the O-active group such as -NCO, -CH(O)CH- of the second raw material in the following way:

[0045]

[0046]

[0047] In the formula (1), -NH2 reacts with -NCO, in the formula (2), -OH reacts with -NCO, and in the formula (3), -OH reacts with -CH(O)CH-. The first raw material is crosslinked to the molecular chain or network of the second raw material, the crosslinked segment migrates to the coating / air interface due to the low surface energy of the first raw material, as shown in Figure 1 , and the surface energy of the coating is reduced, thereby being beneficial to the release of the molded part.

[0048] The cross section of the release coating of the embodiment is shown in Figure 2 After the inner cavity surface of the mold 10 is coated with the release coating 20, the release effect is formed on the inner cavity surface of the mold 10.

[0049] Preferably, in order to improve the bonding force between the release coating 20 and the inner cavity surface of the mold 10, the oil stains and machining residues on the inner cavity surface of the mold 10 are cleaned and dried before the coating is coated, the first raw material and the second raw material are mixed and pre-polymerized by fully stirring, and are deposited on the inner cavity surface of the mold 10 by the film forming process at room temperature.

[0050] Optionally, the film forming process refers to the conventional spraying method, brushing method, scraping method, etc. In the embodiment, in order to simplify the preparation of the coating, the pre-polymer of the first raw material and the second raw material is coated on the inner cavity surface of the mold 10 by brushing or spraying at room temperature, the mold 10 coated with the coating is dried at room temperature, and the release coating 20 is formed after the resin is completely solidified. The solidification time can be set to 24 h.

[0051] Preferably, on the basis of ensuring the release effect, in order not to affect the dimensional accuracy of the molded part, the thickness of the release coating 20 can be set to be less than 20 μm.

[0052] Preferably, as shown in Figure 3As shown, in order to improve the adhesion of the release coating 20 to the surface of the mold 10, an adhesive layer 30 is arranged between the release coating 20 and the inner surface of the mold 10. Before the release coating 20 is applied, the adhesive layer 30 is first applied to the inner surface of the mold 10, and then the release coating 20 is applied to the upper surface of the adhesive layer 30. The release coating 20 is more stably attached to the inner surface of the mold 10 through the adhesive layer 30, thereby improving the stability and service life of the release coating 20. Figure 4 As shown, the specific processing procedure of the release coating 20 is as follows.

[0053] It is worth noting that the adhesive layer does not cause corrosion to the profiled material and can be removed by organic solvents. The adhesive does not need to be treated by organic solvents unless the coating needs to be removed and repaired due to damage. This is different from the cleaning treatment after each use of the release agent.

[0054] Preferably, considering that the material of the mold 10 is usually metal, such as steel, and the main component of the release coating 20 is resin, the adhesive layer 30 is selected to be commercially available epoxy steel glue or polyurethane glue.

[0055] Specifically, the release coating disclosed in the embodiment of the present application has, in mass fraction, 1% of the first raw material of amino-terminated silicone oil and 99% of the second raw material of polyurethane, and the thickness of the coating is 10 μm. The raw material of the adhesive layer is polyurethane glue, and the thickness of the adhesive layer is 10 μm. The material of the profiled mold is NAK80 mold steel. The component of the profiled material is medium-temperature wax, and the melting point thereof is 60-80℃.

[0056] It is worth noting that the mold structures in Examples 2-23 and Comparative Examples 1-3 below are the same as those in the embodiment of the present application, but the profiled materials are different. The profiled material in Examples 16-19 and Comparative Example 2 is rubber, and the melting point thereof is 150℃. The profiled material in Examples 20-23 and Comparative Example 3 is polypropylene plastic, and the melting point thereof is 170℃. The raw materials of the corresponding adhesive layers are also different.

[0057] Example 2

[0058] The difference between the embodiment of the present application and Example 1 is that the release coating disclosed in the embodiment of the present application has, in mass fraction, 4% of the first raw material of amino-terminated silicone oil and 96% of the second raw material of polyurethane.

[0059] Example 3

[0060] The difference between the embodiment of the present application and Example 2 is that the release coating disclosed in the embodiment of the present application has, in mass fraction, 7% of the first raw material of amino-terminated silicone oil and 93% of the second raw material of polyurethane.

[0061] Example 4

[0062] The difference between the embodiment of the present application and embodiment 3 is that the first raw material of the release coating disclosed by the embodiment of the present application is 10% of amino-terminated silicone oil, and the second raw material is 90% of polyurethane.

[0063] Embodiment 5

[0064] The difference between the embodiment of the present application and embodiment 3 is that the second raw material of the release coating disclosed by the embodiment of the present application is 93% of epoxy resin, and the raw material of the adhesive layer is epoxy steel adhesive.

[0065] Embodiment 6

[0066] The difference between the embodiment of the present application and embodiment 5 is that the second raw material of the release coating disclosed by the embodiment of the present application is 93% of phenolic resin, and the raw material of the adhesive layer is phenolic adhesive.

[0067] Embodiment 7

[0068] The difference between the embodiment of the present application and embodiment 6 is that the second raw material of the release coating disclosed by the embodiment of the present application is 93% of acrylic resin, and the raw material of the adhesive layer is acrylic adhesive.

[0069] Embodiment 8

[0070] The difference between the embodiment of the present application and embodiment 3 is that the first raw material of the release coating disclosed by the embodiment of the present application is 7% of epoxy modified silicone oil.

[0071] Embodiment 9

[0072] The difference between the embodiment of the present application and embodiment 8 is that the first raw material of the release coating disclosed by the embodiment of the present application is 7% of alkyl modified silicone oil.

[0073] Embodiment 10

[0074] The difference between the embodiment of the present application and embodiment 9 is that the first raw material of the release coating disclosed by the embodiment of the present application is 7% of polyether modified silicone oil.

[0075] Embodiment 11

[0076] The difference between the embodiment of the present application and embodiment 10 is that the first raw material of the release coating disclosed by the embodiment of the present application is 7% of hydroxyl silicone oil.

[0077] Embodiment 12

[0078] The difference between the embodiment of the present application and embodiment 3 is that the embodiment of the present application does not set the adhesive layer.

[0079] Embodiment 13

[0080] The embodiment of the present application differs from embodiment 12 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% epoxy resin.

[0081] Embodiment 14

[0082] The embodiment of the present application differs from embodiment 13 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% phenolic resin.

[0083] Embodiment 15

[0084] The embodiment of the present application differs from embodiment 14 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% acrylic resin.

[0085] Embodiment 16

[0086] The embodiment of the present application differs from embodiment 3 in that the raw material of the molding material disclosed in the embodiment of the present application is rubber.

[0087] Embodiment 17

[0088] The embodiment of the present application differs from embodiment 16 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% epoxy resin, and the raw material of the adhesive layer is epoxy steel adhesive.

[0089] Embodiment 18

[0090] The embodiment of the present application differs from embodiment 17 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% phenolic resin, and the raw material of the adhesive layer is phenolic adhesive.

[0091] Embodiment 19

[0092] The embodiment of the present application differs from embodiment 18 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% acrylic resin, and the raw material of the adhesive layer is acrylic adhesive.

[0093] Embodiment 20

[0094] The embodiment of the present application differs from embodiment 16 in that the raw material of the molding material disclosed in the embodiment of the present application is polypropylene plastic.

[0095] Embodiment 21

[0096] The embodiment of the present application differs from embodiment 20 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% epoxy resin, and the raw material of the adhesive layer is epoxy steel adhesive.

[0097] Embodiment 22

[0098] The embodiment of the present application differs from example 21 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% phenolic resin, and the raw material of the adhesive layer is phenolic adhesive glue.

[0099] Example 23

[0100] The embodiment of the present application differs from example 22 in that the second raw material of the release coating disclosed in the embodiment of the present application is 93% acrylic resin, and the raw material of the adhesive layer is acrylic adhesive glue.

[0101] Comparative example 1

[0102] In the comparative example, the raw material of the molding material is medium-temperature wax, and no release coating and adhesive layer are provided.

[0103] Comparative example 2

[0104] In the comparative example, the raw material of the molding material is rubber, and no release coating and adhesive layer are provided.

[0105] Comparative example 3

[0106] In the comparative example, the raw material of the molding material is polypropylene plastic, and no release coating and adhesive layer are provided.

[0107] The coating raw materials and properties of the samples prepared in examples 1-23 and comparative examples 1-3 of the present application are shown in Table 1.

[0108] Table 1: Coating raw materials and properties of each sample

[0109]

[0110]

[0111] In the above embodiments of the present application, by providing the release coating 20 on the inner cavity surface of the mold 10, a uniform and lubricating protective layer is formed, which can achieve repeated release of the molded part, thereby eliminating the process of repeatedly spraying and cleaning the release agent. The main function of the release coating 20 is to improve the smoothness of the inner cavity surface of the mold 10, prevent the molding material from adhering to the inner cavity surface of the mold 10, thereby ensuring the surface quality of the molded part and achieving rapid release. Considering the need for long-term repeated use, the release coating 20 is required to have good adhesion and not be easily detached, and to be stably and firmly combined on the inner cavity surface of the mold 10. Considering the convenience of release, the release coating 20 needs to have a small release force between the release coating 20 and the molded part, and also needs to have certain high temperature resistance. In addition, considering that the investment casting is an industrial precision casting method, the surface quality of the workpiece is an important index, therefore the surface roughness of the coating is tested. In order to comprehensively investigate the use effect of the release coating 20, the present application is evaluated by the following method:

[0112] 1. The dewaxing effect is investigated by detecting the contact angle between the inner cavity surface of the mold 10 and the molding material before and after applying the release coating. The contact angle is measured by an OCA25 full-automatic contact angle tester. The specific test method is as follows: the molding material is loaded into the needle tube of the tester and heated to melt into liquid state, and then the inner cavity surface of the mold 10 is heated to the same temperature and the measurement is started; the molding material is pushed out to hang on the needle tip (the needle tube is located above the compression mold), and then the sample table of the compression mold is slowly raised and placed after the molding material is static; the molding material is gently placed on the inner cavity surface of the mold 10, and then the sample table is slowly lowered; after the molding material wets the inner cavity surface of the mold 10 and the shape is stable, a photo is taken, and the included angle between the interface of the molding material and the inner cavity surface of the mold 10 and the tangent of the outer contour of the molding material is the contact angle. Figure 5 Figure is the test diagram of the contact angle between the inventive example 1 and the medium temperature wax liquid. Figure 6 Figure is the test diagram of the contact angle between the inventive example 2 and the rubber. Figure 7 Figure is the test diagram of the contact angle between the inventive example 3 and the polypropylene plastic. Figure 8 Figure is the test diagram of the contact angle between the inventive example 3 and the medium temperature wax liquid.

[0113] 2. The release effect is investigated by detecting the change of the release force required for the molding material to release before and after applying the release coating. The release force is decomposed into pure tension and pure shear force, and the specific test method is as follows: the molding material is melted and dropped into the inner cavity surfaces of two closely arranged molds 10, and the tension and shear force required for the two compression molds to separate are tested by a universal testing machine to test the dewaxing tension and the release shear force.

[0114] 3. The weather resistance of the release coating is investigated by detecting the change of the contact angle between the inner cavity surface of the mold 10 and the molding material after the release coating is used for 10 times of release and 10 days at an environmental temperature of-18℃. The compression mold coated with the release coating is subjected to 10 times of medium temperature wax release process, Figure 9 Figure is the test diagram of the contact angle between the inventive example 3 and the medium temperature wax liquid after 10 times of release. The compression mold coated with the release coating is placed in a refrigerator at-18℃ for 10 days, and then the contact angle is measured. Figure 10 Figure is the test diagram of the contact angle between the inventive example 3 and the medium temperature wax liquid after 10 days of storage at-18℃. The results show that the release coating can maintain stable wax-repellent ability after 10 times of release and 10 days at-18℃.

[0115] 4. The influence of the release coating on the size precision of the molded part is investigated by detecting the surface roughness of the inner cavity surface of the mold 10 before and after applying the release coating. The surface roughness is detected by a surface profilometer.

[0116] The release effects of the samples prepared in the inventive examples 1-23 and the comparative examples 1-3 are shown in Table 2.

[0117] Table 2: Release effects of various samples

[0118]

[0119]

[0120] As can be seen from Tables 1-2, compared with Comparative Examples 1-3 without coating, the contact angle of each of the embodiments with the molding material is greater than that of the corresponding comparative example, and the shear force and tensile stress of each of the embodiments during demolding are also correspondingly lower, so it can be concluded that the demolding coating designed in the present application is beneficial to the demolding process of the molded part in the investment casting, injection molding and rubber molding processes. Comparing the contact angle and demolding force between the coatings with the same raw material and different content, the demolding effect of the coating exists certain difference. Among them, the demolding coating of Example 1 and Example 2 has less amount of silicone oil added, and the resin linked with the silicone oil cannot cover the entire surface of the coating, resulting in a slight deficiency in the demolding ability of the coating. The demolding coating of Example 4 has more silicone oil, and after each resin segment links with more silicone oil, the migration of the segment is blocked, and the silicone oil with low surface energy cannot move to the surface of the coating, thereby reducing the demolding effect of the coating. Therefore, the content range of the group-modified silicone oil in the demolding coating to achieve the demolding effect is 1-10%, and when the first raw material accounts for 4-7%, the coating has better demolding assistance, and when the first raw material accounts for 7%, the demolding effect of the coating reaches the best.

[0121] The second raw material resin of the release coating of Examples 6, 7, 18, 19, 22, and 23 has a high viscosity, resulting in a large surface roughness of the release coating, which is not suitable for molded parts with high requirements for size and surface state; and the resin used in the above examples has a large low-temperature brittleness, which is not suitable for low-temperature environments (when the temperature is low in winter). When the molding material is rubber or polypropylene plastic with a high melting point, the release coating of Examples 16, 19, 20, and 23 has a low service temperature of the resin used, and the chain is damaged at high temperatures, resulting in a decrease in the contact angle with the molding material. The release coating of Examples 5, 17, and 21 has a high use temperature and a low viscosity (lower surface roughness of the coating), which is suitable for molding materials with high temperatures, complex workpieces, and higher requirements for size accuracy, but the reaction between the epoxy groups of the coating and the silicone oil pre-polymerization is violent, and the reaction temperature needs to be controlled, increasing the coating preparation procedure and cost. The coating of Example 8 is also reacted by the epoxy groups and active groups, and the reaction conditions are relatively harsh. The end of the silicone oil of the coating of Example 9 is an alkane with good stability, which is not easy to react with the active groups in the resin, so the release effect of the coating is poor. In Example 10, the modified silicone oil is mainly replaced by a polyether side chain, and the end is still an alkane, so its reactivity with the resin is similar to that of Example 9, and the stress required for release is large. The modified group of Example 11 is more active, which is easy to overreact with the active groups in the resin to increase the molecular weight, and the chain movement is blocked, thereby affecting the release effect. In summary, when the first raw material is selected from amino silicone oil, epoxy modified silicone oil, and hydroxyl silicone oil, the reaction activity is good, and the release effect of the obtained coating is excellent, but the epoxy modified silicone oil and the hydroxyl silicone oil are more active, and it is more difficult to prepare the coating for large-sized molded parts. When the second raw material is selected from epoxy resin and phenolic resin, the use temperature range is relatively wide, polyurethane and acrylic resin are suitable for molding materials with a melting point lower than 80°C, among which, polyurethane has a better surface roughness and is more suitable for the investment casting industry with high requirements for size accuracy; when the melting point of the molding material is higher than 100°C, the service performance of the epoxy resin and the phenolic resin is better, but the surface roughness of the phenolic resin is large, and the active epoxy group is not conducive to the preparation of the coating for large workpieces.

[0122] Examples 12 to 15 are coating systems composed of various types of resins with amino-terminated silicone oil without an intermediate adhesive layer, and the release effect is not affected compared with Examples 3, 5 to 7 corresponding to each of them. The intermediate layer is only used to improve the bonding force between the functional coating and the molding material, and prolong the service life of the release coating.

[0123] Compared with the case where no release agent or the release coating disclosed by the present application is used, the pulling force and shearing force required for the mold to separate from the molding material after the release coating disclosed by the present application is applied are reduced, the release coating is firmly combined with the profiled metal, the adhesive layer is further arranged to strengthen the combination of the release coating and the profiled metal, repeated release can be realized while ensuring the dimensional accuracy and surface roughness of the molded part; compared with the use of the release agent, the present application simplifies the processes and working hours of the investment casting, injection molding and rubber molding processes, saves the production cost; the release coating does not corrode the profiled product and does not release toxic substances during the casting process, the surface of the molded part after release is free of coating residues, repeated release can be realized, and the profiled product does not need to be sprayed before being profiled, which is friendly to the health of workers and the environment.

[0124] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A release coating characterized by, The release coating is prepared from raw materials in the following mass percentage: 1% to 10% of a first raw material and 90% to 99% of a second raw material; wherein the first raw material is a group-modified silicone oil, and the second raw material is a resin with O active groups; the first raw material and the second raw material are pre-polymerized and then formed into the release coating through a film forming process.

2. The release coating according to claim 1, wherein The mass percentage of the first raw material is 4% to 7%.

3. The release coating of claim 2, wherein, The second raw material is an oxygen-containing polyester resin or an epoxy resin.

4. The release coating of claim 3, wherein, The first raw material is an amino-terminated silicone oil or an epoxy-modified silicone oil.

5. A mold characterized in that, The inner cavity surface of the mold is provided with the release coating according to any one of claims 1 to 4.

6. A method of using a release coating characterized by, The inner cavity surface of the mold is provided with the release coating according to any one of claims 1 to 4.

7. The method of using a release coating of claim 6, wherein, An adhesive layer is provided between the inner cavity surface of the mold and the release coating, and the adhesive layer is used to improve the bonding force between the release coating and the inner cavity surface of the mold.

8. The method of using a release coating of claim 7, wherein, The adhesive layer is a cured product of at least one adhesive selected from polyurethane adhesive, epoxy adhesive, phenolic adhesive, and silicone adhesive, and the corresponding adhesive is selected according to the second raw material.

9. The method of using a release coating of claim 8, wherein, The thickness of the release coating is less than 20 μm.

10. A method of processing the release coating according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: cleaning and drying the inner cavity surface of the mold; mixing the first raw material and the second raw material at room temperature and pre-polymerizing by fully stirring; depositing the pre-polymer on the inner cavity surface of the mold through a film forming process, and curing at room temperature for 24 h to form the release coating after the second raw material is completely cured.

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