Internal mold release for polyester molding compounds, process for the preparation and use thereof

Abstract

The present invention relates to an internal mold release agent for polyester molding compound and a method for preparing the same, wherein the reactants of the internal mold release agent include 48-60 parts by weight of a fatty acid, 30-40 parts by weight of an epoxy resin, and 0.01-0.05 parts by weight of a catalyst, and further include 2-20 parts by weight of maleic anhydride and 0.01-0.1 parts by weight of a polymerization inhibitor. The internal mold release agent according to the present invention is in a liquid or paste form, is completely soluble in the resin used in the molding compound, is easy to add, and can achieve excellent mold release with a small amount of the internal mold release agent. The product prepared using the internal mold release agent has a good surface gloss and high quality, and the product to which the internal mold release agent is added does not need to be polished, but only needs to be simply washed, dried, and treated to prepare a product that needs to be sprayed without affecting the adhesion of the product to a primer.

Description

TECHNICAL FIELD

[0001] The present application relates to an internal release agent for polyester molding compound and a preparation method thereof, and belongs to the technical field of high polymer materials. BACKGROUND

[0002] The molding process of polyester molding compound often requires high temperature and mold, and it is difficult to demold after the molding compound is completely cured. The general solution is to add an internal release agent to the polyester molding compound or to spray an external release agent on the mold. Spraying an external release agent is more troublesome and affects production efficiency, and the solvents or small molecule substances in the external release agent can harm the human body. Therefore, the external release agent is only used to assist demolding and is used in small amounts. The most widely used is the internal release agent. Zinc stearate is the most commonly used internal release agent for polyester molding compound because of its low price and good demolding effect. However, with the development of the times and the increasing quality requirements of upstream customers, zinc stearate has also exposed some problems in some high-end products. For example, because zinc stearate is a powdery inorganic product, it is easy to agglomerate, and the dispersion of zinc stearate in liquid resin is particularly important to the surface quality of the molding compound product. If the agglomerated zinc stearate migrates to the surface of the product, it will more or less cause the product surface to bloom and the gloss to deteriorate. Excessive uneven dispersion and agglomeration of zinc stearate can also reduce its demolding ability, causing the product to stick to the mold, and seriously affecting product quality and yield. In addition, most of the products of some high-end automotive parts customers need to be painted and processed for secondary processing. The zinc stearate with demolding effect will mostly migrate to the surface of the product, which will affect the adhesion of the primer to 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, thereby improving the adhesion of the primer to the product and increasing the labor cost, which will cause environmental pollution.

[0003] Chinese patent document CN106079182A discloses an unsaturated polyester resin internal release agent, which comprises phosphorus pentoxide 30-220 parts, cocoa oil 9-18 parts, lecithin 30-90 parts, soybean oil 100-250 parts, linseed oil 50-180 parts, zinc stearate 20-70 parts, and phenolic resin 15-75 parts. Chinese patent document CN112497585A discloses a high-efficiency environmentally friendly internal release agent, which consists of the following components in parts by weight: phenolic compound 20-60 parts, stearic acid 10-40 parts, phenolic resin 20-70 parts, lubricating oil 1-10 parts, and solid powder 15-25 parts. Chinese patent document CN1040758A discloses an internal release agent for unsaturated polyester resin, which is made of lecithin, soybean oil, linseed oil, cocoa oil, and zinc stearate, and the weight percentage of the formula is as follows: lecithin 28-36%, soybean oil 18-22%, linseed oil 18-22%, cocoa oil 9-11%, and zinc stearate 15-19%. The preparation process is as follows: first, the above-mentioned fats and oils are added to a reaction kettle in proportion, stirred at 90-100°C for 10-15 hours to make them fully miscible, 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 release agents in the above-mentioned patents all add inorganic zinc stearate as raw material, and there is a problem of uniform dispersion of zinc stearate. In addition, the adhesion of the product after demolding to paint has not been reported. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an internal release agent for polyester molding material, 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 release agent. In order to solve the above technical problem, the present application provides an internal release agent for polyester molding material, which is obtained by reacting reactants at 120-145°C until the acid value is 10-98 mgKOH / g, the reactants comprising 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.

[0005] Further, the reactants further comprise 2-20 parts by weight of maleic anhydride and 0.01-0.1 parts by weight of polymerization inhibitor.

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

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

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

[0009] Further, the catalyst is triphenylphosphine.

[0010] To solve the above technical problems, the application provides a preparation method of an internal release agent for polyester molding compounds, comprising the following steps:

[0011] A. 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 are added into a reaction kettle, the temperature of the reaction kettle is heated to 120-145 DEG C at a heating rate of 4-6 DEG C per minute, and the reaction is kept until the acid value is less than 10 mgKOH / g;

[0012] B. 5-20 parts by weight of maleic anhydride and 0.01-0.03 parts by weight of second polymerization inhibitor are added, the temperature of the reaction kettle is heated to 120-145 DEG C at a heating rate of 4-6 DEG C per minute, the reaction is kept until the acid value is 10-98 mgKOH / g, and 0.01-0.03 parts by weight of second polymerization inhibitor is further added;

[0013] C. the heating is stopped, and the temperature of the product is reduced to below 70 DEG C, so that the internal release agent is obtained.

[0014] To solve the above technical problems, the application provides a preparation method of an internal release agent for polyester molding compounds, comprising the following steps:

[0015] A. 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 are added into a reaction kettle, the temperature of the reaction kettle is heated to 120-145 DEG C at a heating rate of 4-6 DEG C per minute, and the reaction is kept until the acid value is 10-98 mgKOH / g;

[0016] B. the heating is stopped, and the temperature of the product is reduced to below 70 DEG C, so that the internal release agent is obtained.

[0017] Further, the nitrogen is introduced into the reaction kettle in step A.

[0018] To solve the above technical problems, the application provides an application of the internal release agent for polyester molding compounds as a release agent together with unsaturated polyester resin for preparing unsaturated polyester molding compounds.

[0019] The positive effect of the present application: the present application solves the performance deficiency of traditional internal release agent zinc stearate applied to polyester molding compound, and synthesizes the internal release agent for polyester molding compound by the reaction of fatty acid with epoxy resin through a certain process. The internal release agent provided by the present application is liquid or paste, can be completely compatible with the resin used in the molding compound, and is easy to add. Only a small amount of the internal release agent can achieve excellent release effect, the product prepared by the internal release agent has good surface gloss and high quality, and importantly, the product added with the internal release agent does not need to be polished, but only needs to be simply cleaned and dried to prepare the product that needs to be sprayed, and the adhesion of the product and the primer is not affected, two processes of polishing and puttying are reduced, the product can be directly sprayed with primer, which not only saves the labor cost, but also reduces the environmental pollution and energy consumption in the polishing process, and protects the health of the operators. The preparation method of the present application is simple, easy to popularize, and has a wide application prospect. DETAILED DESCRIPTION

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

[0021] Example 1

[0022] The preparation method of the internal release agent for polyester molding compound in the present embodiment comprises the following steps:

[0023] A. Nitrogen is introduced into a reaction kettle, 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 first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol are added into the reaction kettle, the temperature of the reaction kettle is heated to 125℃ at a heating rate of 4℃ per minute, and the reaction is kept until the acid value is less than 10 mgKOH / g.

[0024] B. 9.77 parts by weight of maleic anhydride and 0.01 parts by weight of second polymerization inhibitor methyl hydroquinone are added, the temperature of the reaction kettle is heated to 125℃ at a heating rate of 4℃ per minute, and the reaction is kept until the acid value is 55.1 mgKOH / g, and then 0.01 parts by weight of second polymerization inhibitor methyl hydroquinone is added.

[0025] C. Stop heating, and the product temperature is reduced to below 70℃ to obtain the internal release agent.

[0026] Example 2

[0027] The preparation method of the internal release agent for polyester molding compound in the present embodiment comprises the following steps:

[0028] A. In a reaction kettle, nitrogen was bubbled into the kettle, 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 first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reaction kettle, the temperature of the reaction kettle was heated to 130°C at a heating rate of 5°C per minute, and the reaction was kept until the acid value was less than 10 mgKOH / g.

[0029] B. 17.05 parts by weight of maleic anhydride and 0.01 parts by weight of second polymerization inhibitor methylhydroquinone were added, the temperature of the reaction kettle was heated to 130°C at a heating rate of 5°C per minute, and the reaction was kept until the acid value was 97.2 mgKOH / g, and then 0.01 parts by weight of second polymerization inhibitor methylhydroquinone was added.

[0030] C. The heating was stopped, and the temperature of the product was reduced to below 70°C to obtain the internal mold release agent.

[0031] Example 3

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

[0033] A. In a reaction kettle, nitrogen was bubbled into the kettle, 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 first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reaction kettle, the temperature of the reaction kettle was heated to 140°C at a heating rate of 6°C per minute, and the reaction was kept until the acid value was less than 10 mgKOH / g.

[0034] B. 9.88 parts by weight of maleic anhydride and 0.01 parts by weight of second polymerization inhibitor methylhydroquinone were added, the temperature of the reaction kettle was heated to 140°C at a heating rate of 6°C per minute, and the reaction was kept until the acid value was 53.5 mgKOH / g, and then 0.01 parts by weight of second polymerization inhibitor methylhydroquinone was added.

[0035] C. The heating was stopped, and the temperature of the product was reduced to below 70°C to obtain the internal mold release agent.

[0036] Example 4

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

[0038] A. In a reaction kettle, nitrogen was introduced, 48.94 parts by weight of flaxseed 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 first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reaction kettle, the temperature of the reaction kettle was heated to 145℃ at a heating rate of 5℃ per minute, and the reaction was kept until the acid value was less than 10 mgKOH / g.

[0039] B. 17.23 parts by weight of maleic anhydride and 0.01 parts by weight of second polymerization inhibitor methyl hydroquinone were added, the temperature of the reaction kettle was heated to 145℃ at a heating rate of 5℃ per minute, and the reaction was kept until the acid value was 93.1 mgKOH / g, and then 0.02 parts by weight of second polymerization inhibitor methyl hydroquinone was added.

[0040] C. The heating was stopped, and the product temperature was reduced to below 70℃ to obtain the internal release agent.

[0041] Example 5

[0042] The preparation method of the internal release agent for polyester molding compound in this example comprises the following steps:

[0043] A. In a reaction kettle, nitrogen was introduced, 59.66 parts by weight of flaxseed 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 first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reaction kettle, the temperature of the reaction kettle was heated to 145℃ at a heating rate of 5℃ per minute, and the reaction was kept until the acid value was 10 mgKOH / g; and then 0.02 parts by weight of second polymerization inhibitor methyl hydroquinone was added.

[0044] B. The heating was stopped, and the product temperature was reduced to below 70℃ to obtain the internal release agent.

[0045] Example 6

[0046] The preparation method of the internal release agent for polyester molding compound in this example comprises the following steps:

[0047] A. In a reaction kettle, nitrogen was introduced, 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 first polymerization inhibitor 2,6-di-tert-butyl-4-methylphenol were added into the reaction kettle, the temperature of the reaction kettle was heated to 135℃ at a heating rate of 6℃ per minute, and the reaction was kept until the acid value was 12.1 mgKOH / g; and then 0.02 parts by weight of second polymerization inhibitor methyl hydroquinone was added.

[0048] B. The heating was stopped, and the product temperature was reduced to below 70℃ to obtain the internal release agent.

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

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

[0051] Performance index 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 State at normal temperature (15°C) Paste Paste Liquid Liquid Liquid Liquid

[0052] The internal release agent of the polyester molding compound in the six embodiments of the present application is prepared into a hand plate according to the typical SMC sheet molding compound formula in Table 2.

[0053] Table 2 SMC sheet molding compound formula table

[0054] Components Proportion 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 Ultra-fine calcium carbonate LD-400 160 parts by weight Thickening agent MA-25C 4 parts by weight Glass fiber ECT55-4800 18% of SMC weight

[0055] The amount of glass fiber in the SMC typical formula is 18% of the weight of SMC, and is a short fiber with a length of 25 mm that has been cut, and the rest of the raw materials are configured by weight fraction. Unsaturated polyester resin PS-520, low shrinkage agent PS-954C, color paste HRC30004 and thickening agent MA-25C are products of Changzhou Huarixin New Material Co., Ltd. Curing agent TBPB is produced by AkzoNobel. Ultra-fine calcium carbonate LD-400 is produced by Lida Ultrafine Industry Co., Ltd. Glass fiber ECT55-4800 is produced by Chongqing International Composite Material Co., Ltd.

[0056] The method for making SMC hand plate is as follows: 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 are put into a stirring kettle according to the proportion, stirred uniformly and the temperature is controlled at 35-39℃, the thickening agent MA-25C is added to the stirring kettle and stirred quickly and uniformly, the liquid resin paste is poured on the release film and spread evenly, then the weighed glass fiber is evenly sprinkled, and then the aluminum plastic film is used for packaging after pressing with a roller, and then placed in a 50℃ oven for curing for 24h.

[0057] After preparing SMC hand plates according to the formula in Table 2 using different proportions of liquid internal release agent, the release effect and product surface effect are observed by using a mold, and the adhesion effect with primer is observed by cleaning and painting the pressed plate as shown in Table 3.

[0058] Table 3 Release effect, surface effect, and adhesion effect with primer data table

[0059]

[0060]

[0061] The press used for pressing is a 100-ton press produced by Hefei Hyde Company, and the pressing process is as follows: 1, pressing time: 4 min of pressure keeping; 2, mold pressing pressure: 18 MPa; 3, pressing temperature: upper mold temperature: 150-152 ℃, lower mold temperature: 138-142 ℃; 4, pressing product thickness: 4 mm.

[0062] Evaluation of demolding effect: according to whether there is residual material on the mold after the press is demolded, it is judged according to two levels of excellent and poor, and residual material is judged as poor, and no residual material is judged as excellent.

[0063] Evaluation of surface effect of SMC plate: surface without bloom and haze and gloss greater than or equal to 85 is judged as excellent; surface without bloom and haze and gloss less than 85 is judged as good; surface with bloom or haze and gloss greater than or equal to 85 is judged as medium; surface with bloom or haze and gloss less than 85 is judged as poor.

[0064] Evaluation of adhesion to primer: the pressed plate is first cleaned with water, then cleaned with two passes of deionized water, then dried in an oven at 50 ℃, sprayed with UV paint, then cured in a UV curing channel, and the adhesion is detected after 24 h. The steps of detecting adhesion are as follows: first, use a knife to draw a cross-shaped grid on the paint coating, draw ten knives horizontally and vertically, forming one hundred small squares, the grid is 1 mm x 1 mm; use a brush to brush five or six times in the diagonal direction, clean the small fragments, then use tape to stick on the cut and pull it off; finally, observe the grid area with a magnifying glass. The detection results are as follows: 0 level, paint peeling area greater than 65%; 1 level, some grid parts or all are peeled off, peeling area greater than 35%-65%; 2 level, represents partial peeling or large area paint peeling along the cut edge, even some grid parts are peeled off, area more than 15%-35%; 3 level, represents the cut and intersection edge peeling area greater than 5%-15%; 4 level, which represents small pieces of paint peeling at the intersection of the cut, the actual damage in the grid area is less than or equal to 5%; 5 level, which represents that the grid edge has no peeling, and the cut edge is completely smooth. The UV paint used in the paint adhesion experiment is UB-155 primer produced by Tianjin Enbi Coating Co., Ltd., and the UV curing equipment model is LT-UV102.

[0065] The present application is a high-efficiency liquid internal release agent synthesized by a certain process through the reaction of fatty acid with unsaturated polyester resin having a release effect, which is synthesized after the reaction of epoxy group and fatty acid with unsaturated polyester resin and then the reaction of anhydride group. Since maleic anhydride has a double bond structure, the synthesized liquid internal release agent also has a double bond structure which can react with unsaturated polyester resin, so that the product surface gloss is better. In the pressing process, the reactive double bond in the liquid release agent reacts with unsaturated polyester resin in the product, and the group having release property is uniformly distributed on the product surface to keep lubrication with the mold and ensure smooth release of the product, which can effectively solve the performance deficiency of traditional internal release agent zinc stearate applied to polyester molding compound.

[0066] Obviously, the above embodiments are only examples for clearly illustrating the embodiments of the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to enumerate all the embodiments. The changes or variations which are obviously extended from the spirit of the present application are still within the protection scope of the present application.

Claims

1. An internal release agent for polyester molding compounds, characterized in that, It is obtained by mixing reactants and reacting them at 120-145°C until the acid value is 10mgKOH / g-98mgKOH / g. The reactants include 48-60 parts by weight of fatty acids, 30-40 parts by weight of epoxy resin and 0.01-0.05 parts by weight of catalyst. The epoxy resin is liquid epoxy resin 840S.

2. The internal release agent for polyester molding compounds 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 polymerization inhibitor.

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

4. The internal 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, linolenic acid, and palmitic acid.

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

6. A method for preparing an internal release agent for polyester molding compounds, characterized in that, Includes the following steps: 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 to a reactor, heat the reactor to 120-145°C at a heating rate of 4-6°C per minute, and maintain the temperature until the acid value is less than 10 mg KOH / g. The epoxy resin is liquid epoxy resin 840S. B. Add 5-20 parts by weight of maleic anhydride and 0.01-0.03 parts by weight of the second polymerization inhibitor, heat the reactor to 120-145°C at a heating rate of 4-6°C per minute, and maintain the temperature until the acid value is 10mgKOH / g-98mgKOH / g, then add 0.01-0.03 parts by weight of the second polymerization inhibitor. C. Stop heating and lower the product temperature to below 70°C to obtain the internal release agent.

7. A method for preparing an internal release agent for polyester molding compounds, characterized in that, Includes the following steps: 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 to a reactor, heat the reactor to 120-145°C at a heating rate of 4-6°C per minute, and maintain the temperature until the acid value is 10mgKOH / g-98mgKOH / g, wherein the epoxy resin is liquid epoxy resin 840S; B. Stop heating and lower the product temperature to below 70°C to obtain the internal release agent.

8. The method for preparing an internal release agent for polyester molding compounds according to claim 6 or 7, characterized in that, In step A, nitrogen gas is introduced into the reactor.

9. The use of an internal release agent of the polyester molding compound as described in claim 1, added together with unsaturated polyester resin, for the preparation of unsaturated polyester molding compounds.

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