Preparation method of vinyl ester resin for optimizing heat-release during curing

Abstract

A preparation method of vinyl ester resin for optimizing heat-release during curing includes: (A) providing a vinyl ester, a solvent and a phase change material to perform mixture; (B) performing a heating process to remove the solvent, so as to obtain a vinyl ester resin containing the phase change material. Thereby, the organic PCM material with high heat absorption and good resin affinity can be used as the temperature control agent of the vinyl ester resin during the curing process for avoiding the defects such as bubbles and cracks being generated in the vinyl ester resin.

Claims

1. A preparation method of vinyl ester resin for optimizing heat-release during curing, comprising: (A) providing a vinyl ester, a solvent and a phase change material to perform mixture; and (B) performing a heating process to remove the solvent, so as to obtain a vinyl ester resin containing the phase change material.

2. The preparation method of vinyl ester resin for optimizing heat-release during curing of claim 1, wherein the solvent is ethanol or acetone.

3. The preparation method of vinyl ester resin for optimizing heat-release during curing of claim 1, wherein the phase change material comprises one or more selected from the group consisting of p-xylene dichloride, methyl fumarate, catechol, quinone, acetanilide, succinic anhydride, benzoic acid, stilbene, benzamide, sebacic acid and adipic acid.

4. The preparation method of vinyl ester resin for optimizing heat-release during curing of claim 1, wherein a weight mixing ratio of the phase change material to the vinyl ester ranges from 0.1% to 5%.

5. A preparation method of composite material containing vinyl ester resin, comprising: (a) providing a vinyl ester resin prepared by claim 1, a solvent, a glass fiber, a curing agent and a promoter to perform mixture; and (b) performing a curing process to obtain a composite material containing the vinyl ester resin.

6. The preparation method of composite material containing vinyl ester resin of claim 5, wherein the solvent is ethanol or acetone.

7. The preparation method of composite material containing vinyl ester resin of claim 5, wherein the phase change material comprises one or more selected from the group consisting of p-xylene dichloride, methyl fumarate, catechol, quinone, acetanilide, succinic anhydride, benzoic acid, stilbene, benzamide, sebacic acid and adipic acid.

8. The preparation method of composite material containing vinyl ester resin of claim 5, wherein a weight mixing ratio of the phase change material to the vinyl ester ranges from 0.1% to 5%.

9. The preparation method of composite material containing vinyl ester resin of claim 5, wherein the curing agent is methyl ethyl ketone peroxide (MEKPO).

10. The preparation method of composite material containing vinyl ester resin of claim 5, wherein the promoter is cobalt salt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow diagram illustrating a preparation method of a vinyl ester resin for optimizing heat-release during curing according to the present invention;

(2) FIG. 2 is a flow diagram illustrating a preparation method of a composite material containing a vinyl ester resin according to the present invention; and

(3) FIG. 3 is a schematic diagram illustrating curing processes of the vinyl ester resins containing PCM (i.e. adipic acid) doped with different content ratios according to the present invention.

DETAILED DESCRIPTION

(4) Specific examples will be detailed in the follow description to explain an implementation of the present invention. Those skilled in the art can easily understand an advantage and an effect of the present invention from contents disclosed in this specification.

(5) Generally, a curing process of a vinyl ester resin is guided by a curing agent. A peroxide (i.e. the curing agent) is reacted with cobalt to generate a free radical, and then, a free radical copolymerization of the free radical and a double bond of the vinyl ester resin is performed. Surely, heating alone can also have the double bond of the vinyl ester open to generate the primary free radical, thereby causing a chain extending reaction, but there are two disadvantages that cannot be ignored: (1) if the temperature is too low, the startup of the reaction is slow, and if the temperature is too high, the reaction is difficult to control; (2) the instantaneous rate of the startup of the reaction is quick, but the reaction in final may easily be incomplete. In comparison, curing with the curing agent may effectively control the reaction rate and the reaction in final may be completed, and the quality of the product is stable.

(6) The phase change material (PCM) covers organic molecules and inorganic molecules. The present invention utilizes a characteristic of PCM, which is easy crystallization, for controlling the change of the heat of the system during the curing process of the vinyl ester resin by absorbing and releasing heat in the crystallization-melting phase conversion. The addition of PCM not only absorbs the heat released by the resin during the curing process, but also slowly releases heat to slow down the cooling rate after the curing process is completed. Therefore, due to the addition of PCM, the temperature changing rate in the curing process can be reduced, and the highest temperature that can be achieved in the curing process can be controlled, thereby reducing the defects of the product.

(7) Referring to FIG. 1, FIG. 1 is a flow diagram illustrating a preparation method of a vinyl ester resin for optimizing heat-release during curing according to the present invention. As shown in FIG. 1, the present invention provides a preparation method of a vinyl ester resin for optimizing heat-release during curing, where steps are shown as following: step (A) is providing a vinyl ester, a solvent and a phase change material to perform mixture (step S101), wherein in this example, the solvent in step (A) is acetone, and the phase change material in step (A) is adipic acid; step (B) is performing a heating process to remove the solvent, so as to obtain a vinyl ester resin containing the phase change material (step S102).

(8) Referring to FIG. 2, FIG. 2 is a flow diagram illustrating a preparation method of a composite material containing a vinyl ester resin according to the present invention. As shown in FIG. 2, the present invention provides a preparation method of composite material containing a vinyl ester resin for optimizing heat-release during curing, where steps are shown as following: (a) providing a vinyl ester resin having the phase change material PCM and prepared by the above method, a solvent, a glass fiber, a curing agent and a promoter to perform mixture (step S201), wherein in this example, the curing agent in step (a) is methyl ethyl ketone peroxide (MEKPO), the promoter is cobalt octoate, the solvent is acetone and the phase change material is adipic acid.

(9) In order to verify that the addition of the organic PCM can effectively absorb the heat released by the resin during the curing process and achieve the purpose of decreasing the heating rate and the highest curing temperature, and at the same time, to verify what content ratio of the PCM with the crystal phase may cause the obvious flame retardant effect, the present invention use an example to verify them, the example includes the following steps:

(10) (1) standing the vinyl ester resin containing the organic PCM (i.e. the adipic acid) with different content ratios (total amount in 120 ml) and the reactants, which are the methyl ethyl ketone peroxide (MEKPO), the cobalt octoate and the acetone, etc., in an ice water bath at about 6 C. for 30 minutes respectively;

(11) (2) then, after confirming the temperature equilibrium of all the reactants, mixing the above reactants with the resin and stirring slowly for 15 minutes;

(12) (3) pouring the mixture into a plastic bottle and standing it in an oil bath at approximately 23 C., and then, performing the curing process and a temperature monitoring, so as to know the highest temperature and the curing time in the curing process.

(13) Referring to FIG. 3, FIG. 3 is a schematic diagram illustrating the curing processes of the vinyl ester resins containing the PCM (i.e. the adipic acid) doped with different content ratios according to the present invention. As shown in FIG. 3, variation curves show the temperatures of the resins containing the adipic acid with different content ratios during the curing process, wherein each sample contains the curing agent of 5.0 wt % and the cobalt salt of 0.4 wt %. According to FIG. 3, the present example may obtain the Table 1 having content ratio of PCM, the highest curing temperature and the curing start time. It can be discovered that the highest curing temperature is decreased and the curing start time is delayed when mixing the PCM.

(14) TABLE-US-00001 TABLE 1 The different content ratio of PCM, the highest curing temperature and the curing start time Content ratio of PCM 0.0 wt % 0.5 wt % 1.0 wt % 1.5 wt % 2.0 wt % 3.0 wt % Highest 222 C. 200 C. 173 C. 179 C. 114 C. 47 C. curing temperature Curing ~20 min ~115 min ~120 min ~185 min ~240 min ~300 min start time

(15) Referring to Table 2 and Table 3, Table 2 shows the temperature increasing rate during the curing process of this example, and Table 3 shows the time of released heat during the curing process of this example. As shown in Table 2 and Table 3, from the comparison of the total released heat of the reaction, it can be confirmed that adding different content ratios of the PCM only suppresses the highest temperature in the curing process, and does not affect the reaction progress. The total released heat of the reaction may still be maintained, and therefore, it can be indicated that the curing reaction is performed completely and does not affect the demand intensity. Moreover, the PCM doped with different content ratios affects the temperature rising curve in the curing process. Thus, when the composite material is made of the vinyl ester resin and different materials, the content ratios of the PCM may be determined based on the property of the material.

(16) TABLE-US-00002 TABLE 2 The temperature increasing rate during the curing process Content ratio of PCM (wt %) 0.0 0.5 1.0 1.5 2.0 3.0 Height temperature 116.3 71.8 65.5 41.5 3.3 0.4 increasing rate ( C./min)

(17) TABLE-US-00003 TABLE 3 The time of released heat during the curing process of this example Content ratio of PCM-A 0.0 wt % 0.5 wt % 1.0 wt % 1.5 wt % Start time of 22 min 88 min 128 min 116 min released heat End time of 148 min 226 min 325 min 387 min released heat Total time of 126 min 138 min 197 min 271 min released heat Released heat 247.3 226.2 227.3 249.7 (J/g)

(18) According to the verification of the example, the present invention can decrease the highest curing temperature and the temperature changing rate during the curing process. Therefore, it can greatly reduce the bubbles and cracks in the resin after curing, form a uniform and fine curing structure, and greatly reduce the defects of the interface between the resin and the material (such as the glass fiber).

(19) The above examples are merely to explain the features and effects of the present invention and not to limit the scope of the present invention. Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made without departing from the spirit and scope of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.