CN115160781A

CN115160781A - Production process of high-thermal-conductivity flame-retardant synthetic resin

Info

Publication number: CN115160781A
Application number: CN202210527462.3A
Authority: CN
Inventors: 唐代全; 马世军; 李福辉; 石风浪
Original assignee: Huizhou Chuangxinlong Industrial Co ltd
Current assignee: Huizhou Chuangxinlong Industrial Co ltd
Priority date: 2022-05-16
Filing date: 2022-05-16
Publication date: 2022-10-11

Abstract

The invention discloses a production process of high-thermal-conductivity flame-retardant synthetic resin, which belongs to the technical field of synthetic resin production processes, and comprises the steps of adding cyanate ester resin into a reaction kettle, and then raising the temperature in the reaction kettle to 125 ℃ so as to completely melt the cyanate ester resin; then, adding the organic phosphorus-containing flame retardant into the reaction kettle for multiple times, and maintaining the temperature in the reaction kettle at 125 ℃; then adding boron nitride or aluminum nitride into the reaction kettle, and raising the temperature in the reaction kettle to 150 ℃ to melt the blend; then, starting a stirrer to uniformly disperse the components, and vacuumizing for 30 minutes; and finally, pouring the defoamed blend into a mold with the preheating temperature of 150 ℃, treating according to a preset curing system, naturally cooling the blend to room temperature after curing is finished, and demolding. The invention solves the technical problem of how to improve the heat conductivity and the flame retardant level of the cyanate ester synthetic resin.

Description

Production process of high-thermal-conductivity flame-retardant synthetic resin

Technical Field

The invention relates to the technical field of synthetic resin production processes, in particular to a high-heat-conductivity flame-retardant synthetic resin production process.

Background

The high-performance thermosetting resin has important application in many advanced industrial fields such as aerospace, electronic information, electrical insulation and the like due to excellent comprehensive performance. Cyanate Ester (CE) resin is a typical high performance thermosetting resin, and has excellent properties after curing, such as low dielectric constant and loss, excellent thermal properties, and high glass transition temperature. However, in recent years, there has been an increasing demand for high-performance thermosetting resins having high flame retardancy and suppressing toxic volatiles. Although cyanate ester has excellent dimensional stability and thermal stability, it still has the disadvantages of low thermal conductivity, etc.; thus, it still cannot meet its severe use requirements in some sophisticated fields. Hybrid organic polymer or inorganic particle composites have attracted a great deal of research interest, which combine the advantages of organic polymers and inorganic particles, such as easy processing, low dielectric properties, high thermal stability, good mechanical properties, etc., and this process is dedicated to meet the ever-increasing demand for high-performance polymer materials.

Based on the above, chinese patent CN108264765B discloses a preparation method of a toughened, heat-conducting and insulating cyanate resin-based composite material. The method comprises the following steps: step (1), surface modification of hexagonal boron nitride; step (2), preparing an environment-friendly acrylate core-shell toughener emulsion; step (3), preparing composite particles; and (4) preparing the toughened heat-conducting insulating cyanate resin-based composite material, namely preparing boron nitride emulsion treated by a silane coupling agent by adopting a hydrothermal synthesis method, and preparing composite particles by utilizing a freeze drying technology. According to the preparation method of the toughening heat-conducting insulating cyanate ester resin matrix composite, a small amount of composite particles are added into a resin matrix, so that the mechanical property of the thermosetting material is kept excellent while the heat conductivity of the obtained cyanate ester composite is improved, and the toughening heat-conducting effect is also obtained.

However, in the above-disclosed preparation method of the toughened heat-conducting insulating cyanate resin-based composite material, although the toughness of the cyanate resin is improved, there is room for improvement in the heat-conducting and flame-retardant properties of the cyanate resin. In particular, cyanate ester resins have been widely proposed as a replacement for epoxy resins in high temperature applications. However, the electrical and thermal properties of cyanate ester resins themselves are still unsatisfactory, and studies on these properties of cyanate ester resins are still insufficient. Although the cyanate resin contains a large amount of flame-retardant nitrogen elements in the molecule, the cyanate resin has certain flame retardant performance, but the cyanate resin still cannot meet the use requirement in some special use environments. In addition, the heat conductivity of the cyanate ester resin can be reduced while the toughness of the cyanate ester resin is improved; the low thermal conductivity of cyanate ester resins, in turn, causes a large amount of heat energy to build up, which may affect their mechanical properties for long term use at high temperatures. Therefore, it becomes very important to improve the flame-retardant thermal conductivity of the cyanate ester resin. Although, the flame retardant can be added into the cyanate ester resin to improve the flame retardant property; however, from a macroscopic point of view, the thermal conductivity of the polymer mainly depends on the dispersibility and compatibility of the filler in the matrix and whether the thermally conductive network can be effectively formed, and therefore, the properties of the cyanate ester resin can be improved from the point of view of the filler.

Disclosure of Invention

Therefore, it is necessary to provide a production process of a high thermal conductive flame retardant synthetic resin for the technical problem of how to prepare a cyanate ester-based polymer integrating excellent thermal conductive flame retardant property, thermal stability, insulation property and simple preparation process.

A production process of high-thermal-conductivity flame-retardant synthetic resin comprises the following steps:

s1: adding a preset amount of cyanate ester resin into a reaction kettle, and then raising the temperature in the reaction kettle to 125 ℃ to completely melt the cyanate ester resin;

s2: then, adding a preset amount of organic phosphorus-containing flame retardant into the reaction kettle for multiple times, and maintaining the temperature in the reaction kettle at 125 ℃;

s3: then, adding a preset amount of boron nitride into the reaction kettle, and raising the temperature in the reaction kettle to 150 ℃ to melt the blend;

s4: then, starting a stirrer to uniformly disperse the components, and vacuumizing for 30 minutes;

s5: and finally, pouring the defoamed blend into a mold with the preheating temperature of 150 ℃, treating according to a preset curing system, naturally cooling the blend to room temperature after curing is finished, and demolding.

Specifically, in step S2, the organic phosphorus-containing flame retardant is one or a mixture of more of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenyl phosphate, tricresyl phosphate, propylbenzene phosphate, butylbenzene phosphate or cresyldiphenyl phosphate.

Specifically, in step S3, the particle size of the added boron nitride is 0.5 μm, 1 μm, 2 μm, or 4 μm.

Specifically, 10 parts of organic phosphorus-containing flame retardant and 10-40 parts of boron nitride are added for each 100 parts of cyanate ester resin.

Specifically, in step S3, a mixture of 4 μm boron nitride and 50nm aluminum nitride was added to the reaction tank at 20wt% of the amount of cyanate ester resin added, and the temperature in the reaction tank was controlled at 150 ℃ to melt the blend.

Specifically, the ratio of boron nitride to aluminum nitride is 1:1 or 2.

Specifically, the curing system is 180 ℃/4 hours, 220 ℃/2 hours or 260 ℃/2 hours.

In summary, the production process of the high thermal conductivity flame retardant synthetic resin provided by the invention aims at the technical problems of insufficient thermal conductivity and poor flame retardant property of the cyanate ester resin with the characteristics of high-performance thermosetting resin, and firstly, the cyanate ester is modified by the organic phosphorus-containing flame retardant to prepare the phosphorus-containing flame retardant cyanate ester resin; then, adding an inorganic filler into the system of the phosphorus-containing flame-retardant cyanate ester resin; the inorganic filler is one or two of boron nitride or aluminum nitride; and the filler is uniformly dispersed in the matrix to form a heat conduction path; thereby improving the heat-conducting property of the cyanate ester synthetic resin. In addition, the inorganic material or the organic composite material contained in the cyanate ester synthetic resin forms a synergistic flame retardant effect, thereby improving the flame retardant capability of the cyanate ester synthetic resin. Therefore, the production process of the high-heat-conductivity flame-retardant synthetic resin solves the technical problem of how to prepare the cyanate ester-based polymer integrating excellent heat-conductivity flame-retardant property, thermal stability and insulativity and a simple preparation process.

Drawings

FIG. 1 is a flow chart of a process for producing a high thermal conductivity flame retardant synthetic resin according to the present invention;

fig. 2 is a thermal conductivity line graph of a cyanate ester cured product prepared by the production process of the high thermal conductivity flame retardant synthetic resin of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will recognize without departing from the spirit and scope of the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the second feature or the first and second features may be indirectly contacting each other through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, fig. 1 is a flow chart of a process for producing a high thermal conductive flame retardant synthetic resin according to the present invention. As shown in FIG. 1, the invention relates to a production process of a high-thermal-conductivity flame-retardant synthetic resin, which comprises the following steps:

Specifically, the cyanate ester resin (CE) is a novel thermosetting resin having a molecular structure including two or more cyanate ester functional groups (-OCN), and the molecular structural formula thereof is: NCO-R-OCN. After the cyclotrimerization reaction of three-OCN groups, rigid triazine ring forms a firm three-dimensional polymer network. In addition, the molecular structure of the cured CE contains a large number of triazine ring structures and aromatic/alicyclic ring structures, which provide the CE with a high glass transition temperature and maintain high strength even under high temperature conditions. The hard triazine ring structure and the aromatic ring are connected by an ether bond which is easy to rotate, and the crosslinking point of the CE is trifunctional, so that the toughness of the CE after curing is relatively good. In the molecular structure of CE, electronegative O atoms and C atoms are symmetrically distributed around a central electropositive C atom, and the triazine ring structure also has symmetry such that its polarity is very small, which can avoid dipole polarization, so CE has a low dielectric constant and dielectric loss tangent.

Furthermore, although CE has excellent overall properties, it is inferior in toughness to other thermosetting resins, and even though CE has higher toughness than other high-performance thermosetting resins, in some special use cases, the interlayer shear strength and fracture toughness thereof still cannot meet the higher application requirements. And the high-purity CE resin has poor thermal reaction performance, and monomers are easy to separate out when the composite material prepreg is prepared. Therefore, CE resins cannot be applied in a wide range due to the above-mentioned deficiencies. The production process of the high-thermal-conductivity flame-retardant synthetic resin takes the cyanate ester resin as a matrix, and organic phosphorus-containing flame retardant and inorganic heat-conducting filler are selected to carry out modification research on the cyanate ester so as to prepare a mixed resin system with excellent heat-conducting, flame-retardant, insulating and other properties. Therefore, on one hand, the organic/inorganic synergistic flame retardant effect is disclosed, and on the other hand, the influence of the type, particle size and content of the heat-conducting filler and single or compound addition on various performances such as the heat conductivity of the phosphorus-containing cyanate is disclosed.

Specifically, according to the prior art, a synergistic flame retardant effect can occur under the combined action of phosphorus and nitrogen, so that the flame retardancy of cyanate can be further improved by performing flame retardant modification on cyanate by using a flame retardant containing phosphorus. The organic phosphorus flame retardant is selected for carrying out flame retardant modification on the organic phosphorus flame retardant, so that the flame retardance of the organic phosphorus flame retardant can be further improved; the organophosphorus flame retardant may be: 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenyl phosphate, tricresyl phosphate, propylbenzene-based phosphate, butylbenzene-based phosphate, tolyldiphenyl phosphate, or the like. The organophosphorus flame retardant has a molecular structure containing P-H bonds with high activity, can react with various functional groups, and shows an excellent gas-phase flame retardant effect. In addition, the flame retardant of the 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide has the advantages of low smoke, low toxicity, good compatibility with polymers, lasting flame retardant effect and the like, so that the flame retardant can be applied to the flame retardance of materials such as electronic circuit boards and the like.

In particular, an effective and economical way to improve the thermal conductivity of the composite is to add thermally conductive fillers to the matrix, including metals such as aluminum or copper, carbonaceous materials such as graphene or multiwall carbon nanotubes, and ceramic particles such as boron nitride, aluminum nitride, or silicon carbide. Among these usable fillers, the metal particles are limited in their applications due to their high density and high conductivity characteristics; the carbonaceous particles exhibit the disadvantages of high cost, poor dispersibility and high conductivity; ceramic particles are widely used because of their low cost, high thermal conductivity, good electrical insulation and thermal stability, etc. Boron nitride-based polymers are expected to meet the heat dissipation requirements of advanced electronic devices because of their good electrical insulation, high thermal conductivity, easy processability, light weight, corrosion resistance, vibration damping properties, and the like. However, the properties of the filler itself have a great influence on the thermal conductivity of the filled composite material, including the thermal conductivity, content, particle size, shape and phase interface of the filler, wherein the size and shape of the filler particles have the most direct influence on the thermal conductivity of the composite material.

Furthermore, the contents of the respective mixtures can be respectively adjusted according to the data in table 1 below, so as to reveal the influence of the particle size and the proportion of the organic phosphorus-containing flame retardant and the filler on the heat conduction and the flame retardant performance of the cyanate ester resin. Wherein, the blank control sample is a sample of pure cyanate ester resin; the flame retardant control is a control with only the flame retardant added and no filler added; 0.5 μm samples 1 to 4 were a control sample in which the particle size of boron nitride was controlled to 0.5 μm; similarly, the samples 4 to 7 having a particle size distribution of 0.5 μm to 4 μm were the control samples in which the particle size distribution of boron nitride was controlled to be 0.5 μm to 4 μm. Respectively carrying out a heat conductivity coefficient test experiment and a limited oxygen index test experiment on each sample according to a vertical combustion test; thereby revealing the influence of the organic phosphorus-containing flame retardant on the heat-conducting property and the flame-retardant property of the modified cyanate ester resin according to the boron nitride. The thermal conductivity test is to use a DRL-II thermal conductivity tester and test the thermal conductivity performance of samples by a steady-state heat flow method, wherein the size of each sample is 30 mm in diameter. The limiting oxygen index test, LOI, means that the limiting oxygen index of the product is measured using an oxygen index measuring instrument according to the standard of ASTM D2863Tests were carried out in which the dimensions of the individual test specimens were 100X 6.5X 3 mm ³ . Further, the vertical burning test, also called UL-94 test, is a test for testing the burning properties of products using a vertical burning tester in accordance with the standard of GBT2408-2008, wherein each test specimen has a size of 130X 13X 3 mm ³ 。

Table 1: cyanate ester resin cured product formula

Furthermore, the heat conduction of the filled heat-conducting polymer material is mainly realized by the vibration of lattice phonons among fillers, wherein the heat conductivity of the filler boron nitride is 300W/mK, while the heat conductivity of the pure cyanate ester resin is only about 0.1W/mK, so that the sufficient contact among BN particles in the cyanate ester matrix is promoted to form a heat-conducting network, which is very critical for improving the heat conductivity of the polymer. The effect of boron nitride content and particle size on the thermal conductivity of different samples is shown in figure 2. As can be seen from fig. 2, as the content of boron nitride increases, the thermal conductivity of the polymer also increases, because the thermal conductivity of the polymer depends on the amount of the filler added. When the amount of boron nitride added was 40wt%, the thermal conductivities of sample 4, sample 5, sample 6 and sample 7 reached 0.28W/mK, 0.24W/mK, 0.21W/mK and 0.20W/mK, respectively. The results show that different particle sizes of BN have different effects on the thermal conductivity of the composite material. The smaller the particle size of the boron nitride is, the higher the thermal conductivity of the polymer is at the same addition amount, and the thermal conductivity of the boron nitride with the four particle sizes is ranked as follows: 0.5 μm >1 μm >2 μm >4 μm. This is because, at the same amount of filler added, the smaller the particle size, the larger the surface area, the larger the contact area with the matrix, and therefore, the better the dispersibility in the matrix, the easier the formation of the heat conduction path, which is advantageous for the transfer of phonons, and the higher the heat conductivity. Further, it can be seen from FIG. 2 that when the boron nitride content is 30wt%, the thermal conductivity of sample 7 is higher than that of sample 6 because the particle size is largest in sample 7, the dispersibility in the matrix is not so good, and the measurement of the thermal conductivity is slightly affected. It can also be seen that the thermal conductivity of the blended systems filled with smaller particle size boron nitride grows faster and faster as the boron nitride content increases. This is because, at a low addition amount of boron nitride, the boron nitride particles are randomly dispersed alone in the cyanate ester resin, and although the thermal conductivity of boron nitride itself is high, in the case where the filler particles do not sufficiently contact each other, the filler cannot form a heat conductive network in the matrix, and most of the filler is surrounded by the cyanate ester resin, and the entire cured product system takes the form of islands, so that the thermal conductivity is low. As the content of boron nitride increases, the boron nitride particles can contact each other, thereby constituting a continuous heat conductive chain throughout the resin matrix and forming a heat conductive path.

Further, the limited oxygen index and the vertical burning rating test are applied to research on the flame retardant performance of the synthetic resin, and the experimental results are shown in the following table 2. As shown in Table 2, the pure CE cured product failed the UL-94 test, but the LOI value was 26.8wt%, which is a combustible material, indicating that the CE itself is not low in LOI value and has a certain flame retardant ability as compared with other resins. This is because CE contains a large amount of nonflammable N element, and the N element is decomposed endothermically during combustion to generate some nonflammable gases, such as NO, NO2, N2, NH3, and CO2, which can reduce the concentration of O2 and combustible gases generated by the thermal decomposition of the polymer in the gas source, and the N oxide can trap radicals to hinder the combustion reaction of the polymer. Then, after the addition of the organic phosphorus flame retardant to CE, the LOI value of the flame retardant control reached 30.5wt%, which was converted into a flame-retardant material with UL-94 rating V-1, indicating that the organic phosphorus flame retardant had high thermal stability and flame retardancy. As is clear from Table 2, the LOI value increases with the addition amount of boron nitride, and reaches a maximum of 33.7wt% when the addition amount of boron nitride is 40 wt%. When the BN addition amount is 40wt%, the smaller the particle diameter of boron nitride is, the higher the LOI value thereof is. When the content of boron nitride is more than 10wt%, that is, the sample shown in test specimen 2-6 reaches V-0 grade in the UL-94 rating test. As can be seen from fig. 2, the flame retardancy of the cyanate ester resin synthetic resin is enhanced as the thermal conductivity is increased. All of samples 2 to 6 except sample 7 achieved a V-0 rating in the UL-94 rating test, and sample 7 showed a LOI value smaller than that of the CEP sample due to the aforementioned less uniform dispersion of boron nitride having a particle size of 4 μm in the matrix. Further, as can be seen from Table 2, the LOI value of the flame retardant control sample is the same as that of the sample of specimen No. 1, thereby showing that the addition of 10% by weight of boron nitride having a particle diameter of 0.5 μm is not flame-retardant with respect to the cyanate ester resin synthetic resin because its content is too small.

Table 2: LOI and UL-94 of cyanate ester synthetic resin

Further, different types of fillers are added in combination to the resin matrix to improve its overall properties compared to a single inorganic filler system, such as: such as BN and AlN, multi-walled carbon nanotubes and SiC, BN and Al ₂ O ₃ BN and multi-wall carbon nano-tube, siO2, BN and CeO ₂ And BN and the like. By comprehensively considering the economy and performance of a polymerization system, the production process of the high-thermal-conductivity flame-retardant synthetic resin disclosed by the invention is disclosed by compounding the ceramic fillers BN and AlN, so that the thermal conductivity and flame retardance of the polymer system are improved while the electrical insulation property of the polymer system is kept. Since the amount of filler added affects the viscosity of the resin/filler blend system, which is a critical parameter for processability. When more filler is added, a larger total filler surface area results in a higher viscosity and thus affects the flowability of the system, and it is therefore important to maintain a certain viscosity. Therefore, a particle size of 50nmALN is preferably selected. Experiments prove that when 30wt% of AlN is added into the phosphorus-containing cyanate, the viscosity of the mixed system is very high, so that the mixed system cannot be smoothly cast into a mold, and therefore, the addition amount of the heat-conducting filler of the mixed system with different components is controlled to be 20wt%, and the compounding ratio of BN and AlN is changed; for example, the ratio of BN to ANL is set to 1:2, 1:1 or 2:1.

Further, in the aforementioned step S3, a mixture of 4 μm boron nitride and 50nm aluminum nitride was added to the reaction tank in an amount of 20wt% of the amount of the cyanate ester resin added, and the temperature in the reaction tank was controlled at 150 ℃ to melt the blend. More specifically, the proportion of boron nitride to aluminum nitride is 1:1 or 2. For example, several examples are shown in table 3 below:

table 3: formulation examples of cyanate ester synthetic resins

In particular, thermal conduction in an electrically insulating material is the process of conducting heat from one particle to its neighbors by phonon transfer, i.e., particle vibration from high vibration frequency atoms to low frequency atoms. The structure of each component in the composite and the interface between the matrix and the filler will have different effects on the heat transfer. The thermal conductivity test tests of the above examples 1 to 3 in combination with comparative example 1 (cyanate ester resin, organic phosphorus-containing flame retardant and boron nitride) and comparative example 2 (cyanate ester resin, organic phosphorus-containing flame retardant and aluminum nitride) revealed that: the thermal conductivity was the highest in comparative example 1 and the lowest in comparative example 2, because the thermal conductivity of the filler itself had a large influence on the thermal conductivity of the mixed resin system, and the thermal conductivity of boron nitride was 300W/mK, whose solid crystal structure and strong atomic bonding facilitated phonon transfer through the lattice. And the thermal conductivity of the aluminum nitride is smaller than that of the boron nitride and is 160W/mK. Thus, mixed particle systems with different filler sizes and geometries increase the likelihood that each particle will contact each other to form an effective conductive path. In a compound system of boron nitride and aluminum nitride, the thermal conductivity of a quaternary blending system under three proportions is higher than that of a ternary blending system with aluminum nitride added independently and lower than that of the ternary blending system with boron nitride added independently, and in addition, the thermal conductivity is higher when the proportion of the quaternary blending system to the aluminum nitride is 1:1, which indicates that the combination of two fillers under the proportion is better.

Further, the limiting oxygen index, LOI, is used as a parameter index for characterizing the combustion behavior of the material and represents the volume fraction of oxygen when the sample can just sustain combustion under the mixed gas condition of oxygen and nitrogen, so that the LOI can evaluate the flame retardant performance of the material. While the vertical burn test, also known as the UL-94 test, can characterize the self-extinguishment of the specimen after burning and the burning rate upon burning. Thus, the flame retardant property of the cyanate ester synthetic resin can be analyzed by the LOI test and the UL-94 rating test. Specific data for the cyanate ester system at different formulation ratios are set forth below in table 4. As can be seen from Table 4, all the polymer systems achieved a flame retardant material, and the LOI value of comparative example 1 was the highest, 29.9; while the LOI value of comparative example 2 was 28.1. In the compounding system of boron nitride and aluminum nitride, the LOI value is not much different when the compounding ratio is 2:1 and 1:1, wherein the ratio is higher than that of the 2:1 system. For the UL-94 rating, the test results for all systems are V-1 rating.

Table 4: LOI and UL-94 of cyanate ester synthetic resin

Specifically, under the condition that the addition amount of the filler is 20wt%, the thermal conductivity of the mixed system of the cyanate ester resin, the organic phosphorus-containing flame retardant and the boron nitride is higher than that of the mixed system of the cyanate ester resin, the organic phosphorus-containing flame retardant and the aluminum nitride. When the two fillers are compounded, the quaternary blend system has the best thermal conductivity at a ratio of 1: 1. In addition, the UL-94 grade of the cyanate ester synthetic resin prepared by the compound filler can reach the V-1 grade level, and a good flame retardant effect can be realized.

Specifically, in the step S5, the curing system is 180 ℃/4 hours, 220 ℃/2 hours or 260 ℃/2 hours; so that different curing stabilities correspond to different curing times, so that the cyanate ester synthetic resin can be demolded after cooling.

In summary, the production process of the high thermal conductivity flame retardant synthetic resin provided by the invention aims at the technical problems of insufficient thermal conductivity and poor flame retardant property of the cyanate ester resin with the characteristics of high-performance thermosetting resin, and firstly, the cyanate ester is modified by the organic phosphorus-containing flame retardant to prepare the phosphorus-containing flame retardant cyanate ester resin; then, adding an inorganic filler into the system of the phosphorus-containing flame-retardant cyanate ester resin; the inorganic filler is one or two of boron nitride or aluminum nitride; and the filler is uniformly dispersed in the matrix to form a heat conduction path; thereby improving the heat-conducting property of the cyanate ester synthetic resin. In addition, the inorganic material or the organic composite material contained in the cyanate ester synthetic resin forms a synergistic flame retardant effect, so that the flame retardant capability of the cyanate ester synthetic resin is improved. Therefore, the production process of the high-thermal-conductivity flame-retardant synthetic resin solves the technical problem of how to prepare the cyanate ester-based polymer integrating excellent thermal-conductivity flame-retardant property, thermal stability and insulativity and a simple preparation process.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A production process of high-thermal-conductivity flame-retardant synthetic resin is characterized by comprising the following steps:

2. The production process of the high-thermal-conductivity flame-retardant synthetic resin according to claim 1, wherein: in step S2, the organic phosphorus-containing flame retardant is one or more of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenyl phosphate, tricresyl phosphate, propylbenzene phosphate, butylbenzene phosphate or cresyldiphenyl phosphate.

3. The production process of the high-thermal-conductivity flame-retardant synthetic resin according to claim 1, wherein: in the step S3, the particle size of the added boron nitride is 0.5 μm, 1 μm, 2 μm or 4 μm.

4. The process for producing a flame-retardant synthetic resin with high thermal conductivity according to claim 1, wherein the process comprises the following steps: 10 parts of organic phosphorus-containing flame retardant and 10-40 parts of boron nitride are added for every 100 parts of cyanate ester resin.

5. The process for producing a flame-retardant synthetic resin with high thermal conductivity according to claim 1, wherein the process comprises the following steps: in step S3, a mixture of 4 μm boron nitride and 50nm aluminum nitride was added to the reaction tank at 20wt% of the amount of cyanate ester resin added, and the temperature in the reaction tank was controlled at 150 ℃ to melt the blend.

6. The process for producing a high thermal conductivity flame retardant synthetic resin according to claim 5, wherein: the proportion of the boron nitride to the aluminum nitride is 1:1 or 2.

7. The process for producing a flame-retardant synthetic resin with high thermal conductivity according to claim 1, wherein the process comprises the following steps: in step S5, the curing regime is 180 ℃/4 hours, 220 ℃/2 hours, or 260 ℃/2 hours.