Low-dielectric modified epoxy resin as well as preparation method and application thereof

Abstract

The invention relates to the technical field of epoxy resin modification, in particular to low-dielectric modified epoxy resin as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing epoxy resin, a curing agent, polyhedral oligomeric silsesquioxane-octa-epoxy group and a catalyst to obtain a resin mixed system, and curing the resin mixed system to obtain the low-dielectric modified epoxy resin. According to the invention, a cage type polysilsesquioxane-octa-epoxy space structure and a group effect are utilized, after anhydride is used as a curing agent, epoxy group ring-opening cross-linking curing is simultaneously carried out with bisphenol A type epoxy resin, a hybrid system is obtained, and the overall dielectric property of the modified epoxy resin is promoted to be improved. Test results show that when the mass ratio of the POSS-101 is 10%, the modified epoxy resin shows a relatively low dielectric constant of about 2.87 under the condition of 1GHz, and the dielectric loss tangent value can reach (0.02). The whole modification scheme is simple in process step, high in operation feasibility and easy for practical production.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin modification, and in particular to a low-dielectric modified epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resin, a key chemical raw material, is a high-molecular-weight oligomer whose molecular structure is based on aliphatic, alicyclic, or aromatic compounds as the backbone, with reactive epoxy groups on side or intermediate surfaces. After reaction, epoxy resin forms a three-dimensional cross-linked network within the material. This material exhibits advantages such as low shrinkage, high adhesion, strong chemical resistance, and excellent mechanical and electrical properties. Consequently, it is widely used in various fields, including machinery, electronics, aerospace, coatings, and adhesives.

[0003] With the continuous development of society and science and technology, ultra-large-scale integrated circuit technology in high-frequency and high-speed fields has placed higher demands on substrate materials. However, the application of traditional epoxy resin materials in high-frequency communication substrates is limited, mainly due to their high dielectric constant and poor insulation, which leads to reduced signal propagation speed and increased transmission loss in the circuit, thereby affecting the efficient transmission of information. In the field of printed circuit boards (PCBs), epoxy resin, as an important component of the base resin of copper-clad laminates, has become the mainstream resin matrix due to its low cost, good heat resistance, and easy processing and molding. However, epoxy resin has poor dielectric properties, especially during the curing process, which produces a large number of secondary alcohol hydroxyl groups. These hydroxyl groups have strong polarity and are easily absorbed by water, resulting in a decrease in the dielectric properties of the copper-clad laminates, seriously affecting their application in high-frequency printed circuit boards. Therefore, how to prepare high-frequency, high-speed, low-dielectric epoxy resin materials has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-dielectric modified epoxy resin and its preparation method and application, so as to solve the problem that traditional epoxy resins contain a large amount of hydroxyl groups in their cured products and have strong polarity, resulting in their dielectric properties not meeting the requirements of high-frequency printed circuit boards.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a low-dielectric modified epoxy resin, comprising the following steps:

[0007] The epoxy resin, the curing agent, the cage-type polysilsesquioxane-octaepoxy group and the catalyst are mixed to obtain a resin mixed system, and the resin mixed system is cured to obtain a low-dielectric modified epoxy resin.

[0008] Optionally, the weight proportion of the cage-type polysilsesquioxane-octaepoxy group in the resin mixing system is 5 to 20%.

[0009] Optionally, the epoxy resin accounts for 48-57% by mass in the resin mixing system; the curing agent accounts for 31-42% by mass in the resin mixing system; and the catalyst accounts for 0.4-0.5% by mass in the resin mixing system.

[0010] Optionally, the epoxy resin includes alicyclic epoxy resin, bisphenol F epoxy resin or bisphenol A epoxy resin.

[0011] Optionally, the structural formula of the cage-type polysilsesquioxane-octaepoxy group is as shown in Formula 1:

[0012]

[0013] Optionally, the curing agent includes methyltetrahydrophthalic anhydride or an amine curing agent.

[0014] Optionally, the catalyst includes 4-(dimethylamino)pyridine or an imidazole catalyst.

[0015] Optionally, the curing is first carried out at 80-90° C. for 2-3 hours, then at 120-130° C. for 2-3 hours, and finally at 160-170° C. for 4-5 hours.

[0016] The present invention also provides a low-dielectric modified epoxy resin prepared by the above preparation method.

[0017] The present invention also provides the use of the low-dielectric modified epoxy resin in high-frequency communication panels.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention utilizes cage-type polysilsesquioxane-octaepoxy (POSS-101) spatial structure and group effect, and after acid anhydride is made into curing agent, carries out epoxy group ring-opening crosslinking and curing simultaneously with bisphenol A type epoxy resin, obtains hybrid system, promotes the overall dielectric properties of modified epoxy resin to improve (that is: reducing dielectric constant improves high-frequency communication signal transmission, simultaneously, reduces dielectric loss tangent and reduces signal loss during communication). Test results show that, when POSS-101 mass accounts for 10%, the modified epoxy resin shows lower dielectric constant of about 2.87 under 1GHz conditions, and dielectric loss tangent value can reach (0.02). The whole modification scheme process step is simple, and operational feasibility is high, and it is easy to produce practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the experimental flow chart of POSS-101 modified bisphenol A epoxy resin;

[0021] Figure 2 The infrared spectra of epoxy systems modified with different mass fractions of POSS-101;

[0022] Figure 3 is the TGA curve of epoxy system modified with different mass fractions of POSS-101;

[0023] Figure 4 SEM images of the POSS-101 / E51 system; wherein: (a) is 0 wt% P, (b) is 5 wt% P, (c) is 10 wt% P, (d) is 15 wt% P, and (e) is 20 wt% P;

[0024] Figure 5 The dielectric properties of the POSS-101 / E51 system are shown in Figure 2, where (a) is the dielectric constant and (b) is the dielectric loss. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] The raw materials used in the present invention can be obtained commercially or prepared using existing technologies.

[0031] The present invention provides a method for preparing a low-dielectric modified epoxy resin, comprising the following steps:

[0032] The epoxy resin, the curing agent, the cage-type polysilsesquioxane-octaepoxy group and the catalyst are mixed to obtain a resin mixed system, and the resin mixed system is cured to obtain a low-dielectric modified epoxy resin.

[0033] The present invention selects cage-type polysilsesquioxane-octaepoxy (POSS-101) as a modifier, regulates its component ratio to improve the dielectric properties of epoxy resin, utilizes the siloxane characteristics of POSS-101 with a macromolecular spatial structure, Si-O alternating cage type, possesses organic properties, and the top Si can carry an organic substituent group. On the basis of maintaining the outer diameter (~1.5nm) and inner diameter (~0.5nm) of the cage structure, it can be effectively blended with other organic materials to prepare functional hybrid materials. On the one hand, the hollow structure can effectively regulate the dielectric properties of the epoxy system. On the other hand, when the R group is an epoxy substituent, based on the epoxy resin curing cross-linking effect, it can react with the phenolic hydroxyl group during the curing stage and can be integrated into the epoxy cured structure, so that POSS-101 can become a part of the modified epoxy hybrid material.

[0034] The invention comprises the following steps: firstly mixing epoxy resin and curing agent, stirring for 20 minutes, then adding cage-type polysilsesquioxane-octaepoxy and continuing to stir for 20 minutes, finally adding catalyst and stirring for 20 minutes, placing the obtained mixture in a vacuum oven, vacuuming and degassing at 55° C. for 30 minutes, and obtaining a resin mixed system after no bubbles are left.

[0035] The present invention pours a resin mixture system into a mold and then solidifies it; before use, a release agent needs to be evenly applied to the surface of the mold, and then the mold is placed in an oven for preheating. The release agent is dimethyl silicone oil, the purity of the dimethyl silicone oil is 99%, and the manufacturer of the dimethyl silicone oil is McLean.

[0036] In the present invention, the mass proportion of the cage-type polysilsesquioxane-octaepoxy group in the resin mixture system is 5-20%, for example, 5%, 10%, 15%, 20%, etc.

[0037] In the present invention, the mass proportion of the epoxy resin in the resin mixing system is 48-57%, preferably 50-56%, more preferably 52-55%, and further preferably 53-54%; the mass proportion of the curing agent in the resin mixing system is 31-42%, preferably 36-40%, and further preferably 37-39%; the mass proportion of the catalyst in the resin mixing system is 0.4-0.5%, preferably 0.42-0.45%.

[0038] In the present invention, the epoxy resin includes alicyclic epoxy resin, bisphenol F epoxy resin or bisphenol A epoxy resin. In an embodiment of the present invention, bisphenol A epoxy resin is preferred. The purity of the bisphenol A epoxy resin is 99%, and the manufacturer of the bisphenol A epoxy resin is McLean.

[0039] In the present invention, the structural formula of the cage-type polysilsesquioxane-octaepoxy group is shown in Formula 1:

[0040]

[0041] The manufacturer of the cage-type polysilsesquioxane-octaepoxy is Guangzhou Yixin Technology Co., Ltd.

[0042] The present invention selects POSS-101 as a modifier for epoxy resins. On the one hand, the abundant organic molecular segments surrounding POSS are easily functionalized, making it highly compatible and particularly suitable for modification. On the other hand, POSS-101 has a highly symmetrical cage structure, resulting in an extremely low dielectric constant and an extremely stable polyhedral core, which makes it heat-resistant and stable. Furthermore, POSS-101 reduces the reactivity of the epoxy resin base, thereby lowering water absorption and improving dielectric properties.

[0043] In the present invention, the curing agent includes methyltetrahydrophthalic anhydride or an amine curing agent, and the amine curing agent is preferably isophoronediamine. In an embodiment of the present invention, the curing agent is preferably methyltetrahydrophthalic anhydride, and the purity of the methyltetrahydrophthalic anhydride is 98%. The manufacturer of the methyltetrahydrophthalic anhydride is Macklin.

[0044] In the present invention, the catalyst includes 4-(dimethylamino)pyridine or an imidazole catalyst, and the imidazole catalyst is preferably 2-methylimidazole. In an embodiment of the present invention, the catalyst is preferably 4-(dimethylamino)pyridine, and the purity of the 4-(dimethylamino)pyridine is 98%. The manufacturer of the 4-(dimethylamino)pyridine is Aladdin.

[0045] In the present invention, the curing is first kept at 80-90°C for 2-3 hours, then kept at 120-130°C for 2-3 hours, and finally kept at 160-170°C for 4-5 hours. In an embodiment of the present invention, it is first kept at 80°C for 2 hours, then kept at 120°C for 2 hours, and finally kept at 160°C for 4 hours.

[0046] The present invention also provides a low-dielectric modified epoxy resin prepared by the above preparation method.

[0047] The present invention also provides the use of the low-dielectric modified epoxy resin in high-frequency communication panels.

[0048] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1

[0050] (1) Take a small amount of release agent (dimethyl silicone oil) and apply it evenly on the surface of the mold, then put the mold into the oven for preheating.

[0051] (2) Weigh 55 parts of E51 epoxy resin, 39.5 parts of methyltetrahydrophthalic anhydride, 5 parts of POSS-101, and 0.5 parts of 4-(dimethylamino)pyridine by weight; mix 55 parts of E51 epoxy resin and 39.5 parts of methyltetrahydrophthalic anhydride and stir, stir for 20 minutes, add 5 parts of POSS-101 to the mixture, continue stirring for 20 minutes, then add 0.5 parts of 4-(dimethylamino)pyridine and continue stirring for 20 minutes, place the mixture in a vacuum oven, evacuate and degas at 55° C. for 30 minutes, and obtain a resin mixture system after no bubbles are left;

[0052] (3) Quickly take the mold out of the oven and slowly pour the above resin mixture into the mold groove;

[0053] (4) Place the mold in an oven and heat treat and cure it at 80°C for 2 hours, 120°C for 2 hours, and 160°C for 4 hours, then turn off the power and allow it to cool naturally;

[0054] (5) After the oven temperature drops to room temperature, the mold is removed from the oven and the sample is taken out of the mold to obtain the POSS-101 modified epoxy resin.

[0055] Example 2

[0056] The only difference from Example 1 is that, by weight, 53 parts of E51 epoxy resin, 36.5 parts of methyltetrahydrophthalic anhydride, 10 parts of POSS-101, and 0.5 parts of 4-(dimethylamino)pyridine were weighed.

[0057] Example 3

[0058] The only difference from Example 1 is that, by weight, 49.5 parts of E51 epoxy resin, 35 parts of methyltetrahydrophthalic anhydride, 15 parts of POSS-101, and 0.5 parts of 4-(dimethylamino)pyridine were weighed.

[0059] Example 4

[0060] The only difference from Example 1 is that, by weight, 48 parts of E51 epoxy resin, 31.5 parts of methyltetrahydrophthalic anhydride, 20 parts of POSS-101, and 0.5 parts of 4-(dimethylamino)pyridine were weighed.

[0061] Comparative Example 1

[0062] The only difference from Example 1 is that POSS-101 is not added.

[0063] Figure 2 is the infrared spectrum of epoxy system modified with different mass fractions of POSS-101. Figure 2 The infrared spectrum results show that the trends of the curves of different POSS-101 contents are roughly consistent with the curve of 0wt% P, but the peak intensities at the corresponding positions are different, indicating that the curing process of the epoxy resin is not affected after the addition of POSS-101. For all modified samples, all spectra at 910cm -1 There is no infrared characteristic peak of epoxy group in the modified materials, which proves that all modified materials have been basically cured and no obvious epoxy group remains. In addition, the Si-O-Si bond stretching vibration peak in POSS-101 is at 1100cm -1 In the spectra of pure E-51 and 0wt% POSS-101, the Si-O-Si bond stretching vibration absorption peak is almost invisible. However, when the POSS-101 content increases to more than 10wt%, the Si-O-Si bond stretching vibration peak becomes slightly more obvious. This may be due to the increase in POSS-101 content, which leads to the crystallization of particles and the increase in the number of particles after agglomeration.

[0064] Figure 3 is the TGA curve of epoxy system modified with different mass fractions of POSS-101. Figure 3As can be seen, the decomposition temperature (Td, 5wt%) when the system weight loss is 5%, the maximum decomposition rate temperature (Td, max) and the residual carbon rate (Yc) data when 800 ℃ are summarized in Table 1. After adding POSS-101, Td, 5wt% is promoted to 364.0 ℃ from 292.9 ℃, and residual amount also increases, indicating that the thermal stability of the material increases as POSS-101 content increases. This is because after POSS-101 adds, on the one hand, an appropriate amount of POSS-101 contains epoxy group, which can form crosslinking with epoxy resin when curing, and crosslinking density increases, and segment flexibility descends, thereby improving thermal decomposition temperature and residual carbon rate; on the other hand, there is a larger Si-O bond, Si-C bond and the O on the POSS-101 molecular cage structure of bond energy in the system and the hydroxyl on the epoxy resin molecular chain to form hydrogen bonding, and the POSS-101 molecule contains a cage-type similar SiO2 inorganic structure, which itself has excellent heat resistance. However, as the POSS-101 content continues to increase, the molecules agglomerate, resulting in interface defects and reduced dispersion. Furthermore, the agglomerates may become heat conduction channels or stress concentration points, weakening the integrity of the protective layer and reducing the carbon residue rate.

[0065] Table 1 Thermogravimetric data of POSS-101 / E51 system

[0066]

[0067] The cross-sectional SEM images of epoxy resin materials obtained by mixing epoxy resin E-51 with methyltetrahydrophthalic anhydride curing agent and heating them with different contents of POSS-101 are shown in the figure. Figure 4 As shown by Figure 4 It can be seen that without adding POSS-101 ( Figure 4 a) and adding 5 wt% POSS-101 ( Figure 4 b) The fracture surface of the obtained sample is relatively smooth, showing a typical brittle fracture. As the POSS-101 content increases, the fracture surface of the POSS-101 / E51 sample gradually becomes wrinkled and rough ( Figure 4 c, d), especially POSS-101 content of 20wt% ( Figure 4 e), there are a lot of tear bands in the sample, which can absorb a lot of energy when fracture occurs and enhance the mechanical properties of epoxy.

[0068] Figure 5 This is the dielectric performance diagram of the POSS-101 / E51 system. POSS-101 is a weakly polar material with a low dielectric constant and a strong steric hindrance effect. Introducing it into the polymer will restrict the movement of the molecular chain, reduce the free volume, and lower the dielectric constant. Figure 5As can be seen in, when adding POSS-101 mass percent is 5wt% and 10wt%, two kinds of sample dielectric constant and dielectric loss angle all reduce, lower than the sample (0wt%P) value that does not add POSS-101. When POSS-101 content increases to 15wt%, sample dielectric loss begins to rise, higher than the sample (0wt%P) value that does not add POSS-101; And after adding 20wt%POSS-101, sample dielectric constant begins to rise, higher than the sample (0wt%P) value that does not add POSS-101. Therefore, along with the further increase of POSS-101 addition, the dielectric properties of epoxy resin are not reduced always, but the dielectric properties of sample are adversely affected on the contrary. When POSS-101 addition is at 10%, the dielectric properties of sample are best, and at this moment, the decline of epoxy polarity to dielectric properties and the improvement of spatial volume to dielectric properties reach optimal equilibrium state. When the POSS-101 content exceeds 10%, the influence of polarity on the dielectric properties becomes dominant; when the content is less than 10%, the influence of spatial volume on the dielectric properties becomes dominant. In summary, for the POSS-101 / EP system, the dielectric properties are optimal when the POSS-101 addition amount is 10%, with the material dielectric constant dropping to 2.87 (1GHz) and the dielectric loss factor dropping to 0.02 (1GHz).

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a low dielectric modified epoxy resin, characterized in that: The following steps are involved: The epoxy resin, the curing agent, the cage-type polysilsesquioxane-octaepoxy group and the catalyst are mixed to obtain a resin mixed system, and the resin mixed system is cured to obtain a low-dielectric modified epoxy resin.

2. The preparation method according to claim 1, characterized in that The weight proportion of the cage-type polysilsesquioxane-octaepoxy group in the resin mixing system is 5 to 20%.

3. The preparation method according to claim 1, characterized in that The mass proportion of the epoxy resin in the resin mixing system is 48-57%; the mass proportion of the curing agent in the resin mixing system is 31-42%; and the mass proportion of the catalyst in the resin mixing system is 0.4-0.5%.

4. The preparation method according to claim 3, characterized in that The preparation method according to claim 1, characterized in that the epoxy resin comprises an alicyclic epoxy resin, a bisphenol F epoxy resin or a bisphenol A epoxy resin.

5. The preparation method according to claim 2, characterized in that The structural formula of the cage-type polysilsesquioxane-octaepoxy group is shown in Formula 1:

6. The preparation method according to claim 3, characterized in that The curing agent includes methyltetrahydrophthalic anhydride or an amine curing agent.

7. The preparation method according to claim 3, characterized in that The catalyst includes 4-(dimethylamino)pyridine or imidazole catalyst.

8. The preparation method according to claim 1, characterized in that The curing is firstly kept at 80-90° C. for 2-3 hours, then kept at 120-130° C. for 2-3 hours, and finally kept at 160-170° C. for 4-5 hours.

9. The low dielectric modified epoxy resin prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the low-dielectric modified epoxy resin according to claim 9 in the matrix resin of high-frequency low-dielectric board materials.

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