Internal release agent for polyester molding compound as well as preparation method and application of internal release agent

Abstract

The invention relates to an internal release agent of a polyester molding compound and a preparation method of the internal release agent, reactants of the internal release agent comprise 48-60 parts by weight of fatty acid, 30-40 parts by weight of epoxy resin and 0.01-0.05 part by weight of a catalyst, and the reactants further comprise 2-20 parts by weight of maleic anhydride and 0.01-0.1 part by weight of a polymerization inhibitor. The internal release agent provided by the invention is liquid or paste, can be completely dissolved in resin used in a molding compound and is easy to add, an excellent demolding effect can be achieved only by using a small amount of the internal release agent, a product prepared from the internal release agent is good in surface gloss and high in quality, and the product added with the internal release agent does not need to be polished, so that the production cost is reduced. A product needing to be sprayed can be prepared only through simple cleaning and drying treatment, and the adhesive force of the product and the primer is not affected.

Description

Technical Field

[0001] The invention relates to an internal mold release agent for polyester molding materials and a preparation method of the internal mold release agent, belonging to the technical field of polymer materials. Background Art

[0002] The molding process of polyester molding compounds often requires high temperature and molds. After the molding compounds are completely cured, they will be combined with the molds and difficult to demold. The general solution is to add internal mold release agents to the polyester molding compounds or spray external mold release agents on the molds. Because spraying external mold release agents is troublesome and affects production efficiency, and the solvents or small molecules in the external mold release agents are harmful to the human body, external mold release agents are only used to assist demolding and are used in small amounts. The most widely used is the internal mold release agent. Zinc stearate is currently the most used internal mold release agent for polyester molding compounds because of its low price and good demolding effect. However, with the development of the times and the increasing requirements of upstream customers for product quality, zinc stearate has also exposed some of its problems in some high-end products. For example, because zinc stearate is a powdered inorganic product, it is easy to agglomerate. The dispersion of zinc stearate in liquid resin is particularly important for the surface quality of molding compound products. If the agglomerated zinc stearate migrates to the surface of the product, it will more or less cause the surface of the product to become flowery and the gloss to deteriorate. Excessive uneven dispersion and agglomeration of zinc stearate may also reduce its demoulding ability, causing sticking of products, seriously affecting product quality and yield rate. In addition, most products of some high-end automotive parts customers need to undergo secondary processing such as painting. Most of the zinc stearate, which has a demoulding effect, will migrate to the surface of the product, affecting the adhesion between the primer and the product, thereby affecting the painting effect. These manufacturers often adopt the method of polishing the surface of the product to remove the zinc stearate that affects the adhesion of the primer to improve the bonding between the primer and the product, which increases labor costs and causes certain environmental pollution.

[0003] Chinese patent document CN106079182A discloses an unsaturated polyester resin internal mold release agent, including 30-220 parts of phosphorus pentoxide, 9-18 parts of cocoa butter, 30-90 parts of lecithin, 100-250 parts of soybean oil, 50-180 parts of linseed oil, 20-70 parts of zinc stearate, and 15-75 parts of phenolic resin. Chinese patent document CN112497585A discloses an efficient and environmentally friendly internal mold release agent, which is composed of the following components by weight: 20-60 parts of phenolic compounds, 10-40 parts of stearic acid, 20-70 parts of phenolic resin, 1-10 parts of lubricating oil, and 15-25 parts of solid powder. Chinese patent document CN1040758A discloses an internal mold release agent for unsaturated polyester resin, which is made of lecithin, soybean oil, linseed oil, cocoa butter, and zinc stearate. The weight percentage of its formula is lecithin 28-36%, soybean oil 18-22%, linseed oil 18-22%, cocoa butter 9-11%, and zinc stearate 15-19%. Its preparation process is as follows: first, the above-mentioned fat and oil are added to the reactor in proportion, stirred at 90-100°C for 10-15 hours to fully dissolve each other, and finally zinc stearate is added, and the product is obtained by continuing to stir at 90-100°C for 3-5 hours. The internal mold release agent in the above patents will add inorganic zinc stearate as a raw material, and there is a problem of uniform dispersion of zinc stearate. In addition, there is no report on the adhesion of the demoulding product to the paint. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an internal mold release agent for polyester molding materials, which has good compatibility with resin, is easy to add, has good product surface gloss, high quality, does not need to be polished, and has good adhesion to primer, as well as a preparation method and application of the internal mold release agent. In order to solve the above technical problems, the present invention provides an internal mold release agent for polyester molding materials, which is obtained by mixing reactants and reacting at 120 to 145° C. until the acid value is 10 mgKOH / g to 98 mgKOH / g, wherein the reactants include 48 to 60 parts by weight of fatty acid, 30 to 40 parts by weight of epoxy resin, and 0.01 to 0.05 parts by weight of catalyst.

[0005] Furthermore, the reactants further include 2 to 20 parts by weight of maleic anhydride and 0.01 to 0.1 parts by weight of a polymerization inhibitor.

[0006] Furthermore, the polymerization inhibitor is one or both of 2,6-di-tert-butyl-4-methylphenol and methyl hydroquinone.

[0007] Furthermore, the fatty acid is one or more of stearic acid, linseed oil fatty acid and palmitic acid.

[0008] Furthermore, the epoxy resin is liquid epoxy resin 840S.

[0009] Furthermore, the catalyst is triphenylphosphine.

[0010] In order to solve the above technical problems, the present invention provides a method for preparing an internal mold release agent for polyester molding materials, comprising the following steps:

[0011] A. adding 48 to 60 parts by weight of fatty acid, 30 to 40 parts by weight of epoxy resin, 0.01 to 0.05 parts by weight of catalyst and 0.01 to 0.05 parts by weight of first polymerization inhibitor into a reaction kettle, heating the reaction kettle to 120 to 145° C. at a heating rate of 4 to 6° C. per minute, and keeping the temperature to react until the acid value is less than 10 mgKOH / g;

[0012] B. Add 5 to 20 parts by weight of maleic anhydride and 0.01 to 0.03 parts by weight of a second polymerization inhibitor, heat the reactor to 120 to 145° C. at a heating rate of 4 to 6° C. per minute, keep the reaction mixture warm until the acid value is 10 mgKOH / g to 98 mgKOH / g, and then add 0.01 to 0.03 parts by weight of the second polymerization inhibitor;

[0013] C. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0014] In order to solve the above technical problems, the present invention provides a method for preparing an internal mold release agent for polyester molding materials, comprising the following steps:

[0015] A. 48 to 60 parts by weight of fatty acid, 30 to 40 parts by weight of epoxy resin, 0.01 to 0.05 parts by weight of catalyst and 0.01 to 0.05 parts by weight of first polymerization inhibitor are added into a reaction kettle, and the temperature of the reaction kettle is heated to 120 to 145° C. at a heating rate of 4 to 6° C. per minute, and the reaction is kept warm until the acid value reaches 10 mgKOH / g to 98 mgKOH / g;

[0016] B. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0017] Furthermore, in step A, nitrogen is introduced into the reactor.

[0018] In order to solve the above technical problems, the present invention provides an internal mold release agent for polyester molding materials, which is added together with unsaturated polyester resin as a mold release agent for preparing unsaturated polyester molding materials.

[0019] Positive effects of the present invention: The present invention solves the shortcomings of the traditional internal mold release agent zinc stearate in the performance of polyester molding materials, and reacts fatty acids with a demoulding effect with epoxy resins through a certain process to synthesize an internal mold release agent for polyester molding materials. The internal mold release agent provided by the present invention is in liquid or paste form, can be completely soluble in the resin used in the molding material, and is easy to add. Only a small amount of the internal mold release agent is needed to achieve an excellent demoulding effect, and the surface gloss of the product prepared by it is good and the quality is high. What is important is that the product added with the internal mold release agent does not need to be polished, and only a simple cleaning and drying process is required to prepare the product to be sprayed, and it will not affect the adhesion between the product and the primer, reducing the two processes of polishing and scraping putty to fill defects. The product can be directly sprayed with primer, which not only saves labor costs, but also reduces environmental pollution and energy consumption during the polishing process, and protects the health of operators. The preparation method of the present invention is simple, easy to promote, and has broad application prospects. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0021] Example 1

[0022] The preparation method of the internal mold release agent for polyester molding material of this embodiment comprises the following steps:

[0023] A. Nitrogen was introduced into a reactor, and 53.83 parts by weight of stearic acid, 36.35 parts by weight of epoxy resin 840S, 0.03 parts by weight of catalyst triphenylphosphine, and 0.01 parts by weight of the first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reactor, and the reactor temperature was heated to 125° C. at a heating rate of 4° C. per minute, and the reaction was kept warm until the acid value was less than 10 mgKOH / g.

[0024] B. Add 9.77 parts by weight of maleic anhydride and 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone, heat the reactor to 125°C at a heating rate of 4°C per minute, keep the reaction mixture warm until the acid value reaches 55.1 mgKOH / g, and then add 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone.

[0025] C. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0026] Example 2

[0027] The preparation method of the internal mold release agent for polyester molding material of this embodiment comprises the following steps:

[0028] A. Nitrogen was introduced into a reactor, and 49.48 parts by weight of stearic acid, 33.41 parts by weight of epoxy resin 840S, 0.03 parts by weight of catalyst triphenylphosphine, and 0.01 parts by weight of the first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reactor, and the temperature of the reactor was heated to 130° C. at a heating rate of 5° C. per minute, and the reaction was kept warm until the acid value was less than 10 mgKOH / g.

[0029] B. Add 17.05 parts by weight of maleic anhydride and 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone, heat the reactor to 130°C at a heating rate of 5°C per minute, and keep the reaction until the acid value reaches 97.2 mgKOH / g, then add 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone.

[0030] C. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0031] Example 3

[0032] The preparation method of the internal mold release agent for polyester molding material of this embodiment comprises the following steps:

[0033] A. Nitrogen was introduced into a reactor, 53.3 parts by weight of linseed oil fatty acid, 36.76 parts by weight of epoxy resin 840S, 0.03 parts by weight of catalyst triphenylphosphine and 0.01 parts by weight of the first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reactor, the reactor temperature was heated to 140° C. at a heating rate of 6° C. per minute, and the temperature was kept to react until the acid value was less than 10 mgKOH / g.

[0034] B. Add 9.88 parts by weight of maleic anhydride and 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone, heat the reactor to 140°C at a heating rate of 6°C per minute, keep the reaction mixture warm until the acid value reaches 53.5 mgKOH / g, and then add 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone.

[0035] C. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0036] Example 4

[0037] The preparation method of the internal mold release agent for polyester molding material of this embodiment comprises the following steps:

[0038] A. Nitrogen was introduced into a reactor, and 48.94 parts by weight of linseed oil fatty acid, 33.76 parts by weight of epoxy resin 840S, 0.03 parts by weight of catalyst triphenylphosphine and 0.01 parts by weight of the first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reactor, and the temperature of the reactor was heated to 145° C. at a heating rate of 5° C. per minute, and the temperature was kept to react until the acid value was less than 10 mgKOH / g.

[0039] B. Add 17.23 parts by weight of maleic anhydride and 0.01 parts by weight of the second polymerization inhibitor methyl hydroquinone, heat the reactor to 145°C at a heating rate of 5°C per minute, keep the reaction mixture warm until the acid value reaches 93.1 mgKOH / g, and then add 0.02 parts by weight of the second polymerization inhibitor methyl hydroquinone.

[0040] C. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0041] Example 5

[0042] The preparation method of the internal mold release agent for polyester molding material of this embodiment comprises the following steps:

[0043] A. Nitrogen was introduced into a reactor, 59.66 parts by weight of linseed oil fatty acid, 40.29 parts by weight of epoxy resin 840S, 0.03 parts by weight of catalyst triphenylphosphine and 0.01 parts by weight of the first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reactor, the reactor temperature was heated to 145° C. at a heating rate of 5° C. per minute, and the temperature was kept to react until the acid value reached 10 mgKOH / g; and 0.02 parts by weight of the second polymerization inhibitor methylhydroquinone was added.

[0044] B. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0045] Example 6

[0046] The preparation method of the internal mold release agent for polyester molding material of this embodiment comprises the following steps:

[0047] A. Nitrogen was introduced into a reactor, and 32.68 parts by weight of stearic acid, 25.62 parts by weight of palmitic acid, 41.64 parts by weight of epoxy resin 840S, 0.03 parts by weight of catalyst triphenylphosphine and 0.01 parts by weight of the first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reactor, and the reactor temperature was heated to 135° C. at a heating rate of 6° C. per minute, and the temperature was kept to react until the acid value reached 12.1 mgKOH / g; and 0.02 parts by weight of the second polymerization inhibitor methylhydroquinone was added.

[0048] B. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

[0049] The acid value and state of the internal mold release agent of the polyester molding compound in the six embodiments of the present invention are shown in Table 1:

[0050] Table 1 Acid value and state data of internal release agent

[0051] Performance Indicators Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Acid value (mgKOH / g) 55.10 97.20 53.50 93.10 10.00 12.10 At room temperature (15°C) Paste Paste liquid liquid liquid liquid

[0052] The internal mold release agents of the polyester molding compounds in the six embodiments of the present invention were used to prepare handmade boards according to the typical SMC sheet molding compound formula in Table 2.

[0053] Table 2 SMC sheet molding compound formula

[0054] Components Ratio Unsaturated polyester resin PS-520 70 parts by weight Low shrinkage agent PS-954C 30 parts by weight Synthetic liquid internal release agent 3-4 parts by weight Color paste HRC30004 8 parts by weight Curing agent TBPB 1 part by weight Ultrafine Calcium Carbonate LD-400 160 parts by weight Thickener MA-25C 4 parts by weight Glass fiber ECT55-4800 18% of SMC weight

[0055] Among them, the amount of glass fiber in the typical SMC formula is 18% of the weight of SMC, and it is a short fiber that has been cut to a length of 25mm. The remaining raw materials are configured by weight. Unsaturated polyester resin PS-520, low shrinkage agent PS-954C, color paste HRC30004 and thickener MA-25C are products of Changzhou Huari New Materials Co., Ltd. Curing agent TBPB is produced by Akzo Nobel. Ultrafine calcium carbonate LD-400 is produced by Lida Superfine Industry Co., Ltd. Glass fiber ECT55-4800 is produced by Chongqing International Composite Materials Co., Ltd.

[0056] Preparation method of SMC handmade board: put the unsaturated polyester resin PS-520, low shrinkage agent PS-954C, liquid internal release agent, color paste HRC30004 and curing agent TBPB in Table 2 into a stirring kettle according to the ratio and stir evenly, and control the temperature at 35-39°C, add the thickener MA-25C into the stirring kettle and stir quickly and evenly, pour the liquid resin paste on the release film and spread it evenly, then sprinkle the weighed glass fiber evenly, press it with a pressure roller, wrap it with aluminum plastic film and put it in a 50°C oven for aging for 24 hours.

[0057] According to the formula in Table 2, different proportions of liquid internal mold release agents were used to prepare SMC handmade boards, and then they were pressed using molds to see the demoulding effect and product surface effect. The pressed boards were cleaned and sprayed with paint to see the adhesion effect with the primer as shown in Table 3.

[0058] Table 3 Data table of demoulding effect, surface effect, and adhesion effect of primer

[0059]

[0060]

[0061] Among them, the press used for pressing is a 100-ton press produced by Hefei Hyde Company, and the pressing process is: 1. Pressing time: holding pressure 4 minutes; 2. Molding pressure: 18MPa; 3. Pressing temperature: upper mold temperature: 150-152℃, lower mold temperature: 138-142℃; 4. Pressed product thickness: 4mm.

[0062] Evaluation of demoulding effect: It is judged based on whether there is any residual material on the mold after the press demoulding. It is judged according to two grades: excellent and poor. If there is residual material, it is judged as poor, and if there is no residual material, it is judged as excellent.

[0063] Surface effect evaluation of SMC board: if the surface has no flowery or foggy and the gloss is greater than or equal to 85, it is judged as excellent; if the surface has no flowery or foggy and the gloss is less than 85, it is judged as good; if the surface has flowery or foggy and the gloss is greater than or equal to 85, it is judged as medium; if the surface has flowery or foggy and the gloss is less than 85, it is judged as poor.

[0064] Adhesion evaluation with primer: First clean the pressed board with clean water, then clean it with two layers of deionized water, dry it in a 50℃ oven, spray UV paint, and then cure it in a UV curing channel. After 24 hours, test the adhesion. The steps for testing adhesion are as follows: First, use a utility knife to scratch the paint coating in the shape of a cross grid, make ten cuts horizontally and vertically, and form one hundred small squares, with a grid of 1mm×1mm; use a brush to brush five or six times in the diagonal direction to brush off the small fragments, then stick tape on the cut and pull it apart; finally, use a magnifying glass to observe the grid area. The test results are shown in the following test standards: Level 0, the paint peeling area is greater than 65%; Level 1, some squares are partially or completely peeled off, and the peeling area is greater than 35%-65%; Level 2, represents partial peeling or large-scale paint peeling along the edge of the cut, and even some grid parts are peeled off in pieces, with an area of ​​more than 15%-35%; Level 3, represents that the peeling area of ​​the cut and the intersection edge is greater than 5%-15%; Level 4, this represents that there are small pieces of paint peeling at the intersection of the cut, and the actual damage in the grid area is less than or equal to 5%; Level 5, this represents that there is no peeling on the edge of the grid, and the edge of the cut is completely smooth. The UV paint used in the paint adhesion experiment is UB-155 primer produced by Tianjin Enbi Paint Co., Ltd., and the UV curing equipment model is LT-UV102.

[0065] The present invention is a highly efficient liquid internal mold release agent synthesized by reacting fatty acid with demoulding effect with unsaturated polyester resin through a certain process, wherein epoxy group and fatty acid which react with unsaturated polyester resin are synthesized, and then the liquid mold release agent is synthesized with anhydride group. Since maleic anhydride has a double bond structure, the synthesized liquid internal mold release agent also has a double bond structure which can react with unsaturated polyester resin, so that the surface glossiness of the product is better. During the pressing process, the reactive double bond in the liquid mold release agent reacts with the unsaturated polyester resin in the product, and the demoulding group is evenly distributed on the surface of the product and keeps lubrication with the mold to ensure smooth demoulding of the product, which can effectively solve the shortcomings of the traditional internal mold release agent zinc stearate in the performance of polyester molding materials.

[0066] Obviously, the above embodiments are merely examples for clearly illustrating the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. However, these obvious changes or modifications derived from the spirit of the present invention are still within the scope of protection of the present invention.

Claims

1. An internal mold release agent for polyester molding materials, characterized in that: The reactants are mixed and reacted at 120-145° C. until the acid value reaches 10 mgKOH / g-98 mgKOH / g. The reactants include 48-60 parts by weight of fatty acid, 30-40 parts by weight of epoxy resin and 0.01-0.05 parts by weight of catalyst.

2. The internal mold release agent for polyester molding compound according to claim 1, characterized in that: The reactants also include 2 to 20 parts by weight of maleic anhydride and 0.01 to 0.1 parts by weight of a polymerization inhibitor.

3. The internal mold release agent for polyester molding compound according to claim 2, characterized in that: The polymerization inhibitor is one or both of 2,6-di-tert-butyl-4-methylphenol and methyl hydroquinone.

4. The internal mold release agent for polyester molding compounds according to any one of claims 1 to 3, characterized in that The fatty acid is one or more of stearic acid, linseed oil fatty acid and palmitic acid.

5. The internal mold release agent for polyester molding materials according to any one of claims 1 to 3, characterized in that: The epoxy resin is liquid epoxy resin 840S.

6. The internal mold release agent for polyester molding compounds according to any one of claims 1 to 3, characterized in that: The catalyst is triphenylphosphine.

7. A method for preparing an internal mold release agent for polyester molding materials, characterized in that: The following steps are involved: A. Add 48-60 parts by weight of fatty acid, 30-40 parts by weight of epoxy resin, 0.01-0.05 parts by weight of catalyst and 0.01-0.05 parts by weight of first polymerization inhibitor into a reaction kettle, heat the reaction kettle to 120-145°C at a heating rate of 4-6°C per minute, and keep the temperature to react until the acid value is less than 10mgKOH / g; B. Add 5 to 20 parts by weight of maleic anhydride and 0.01 to 0.03 parts by weight of a second polymerization inhibitor, heat the reactor to 120 to 145° C. at a heating rate of 4 to 6° C. per minute, keep the reaction mixture warm until the acid value is 10 mgKOH / g to 98 mgKOH / g, and then add 0.01 to 0.03 parts by weight of the second polymerization inhibitor; C. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

8. A method for preparing an internal mold release agent for polyester molding materials, characterized in that: The following steps are involved: A. Add 48-60 parts by weight of fatty acid, 30-40 parts by weight of epoxy resin, 0.01-0.05 parts by weight of catalyst and 0.01-0.05 parts by weight of first polymerization inhibitor into a reaction kettle, heat the reaction kettle to 120-145°C at a heating rate of 4-6°C per minute, and keep the temperature to react until the acid value reaches 10mgKOH / g-98mgKOH / g; B. Stop heating and reduce the product temperature to below 70°C to obtain an internal release agent.

9. The method for preparing an internal mold release agent for polyester molding materials according to claim 7 or 8, characterized in that: In the step A, nitrogen is introduced into the reaction vessel.

10. Use of the internal mold release agent for polyester molding materials as claimed in claim 1 as a mold release agent added together with unsaturated polyester resin for preparing unsaturated polyester molding materials.

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