阅读说明：本技术 一种作为抗沉降剂的聚硅氧烷对苯二甲酸烯基酯化合物 (Polysiloxane alkenyl terephthalate compound as anti-settling agent ) 是由 袁珊 姜宏伟 郑杰华 于 2021-10-14 设计创作，主要内容包括：本发明属于化工领域,具体涉抗沉降剂的生产合成技术,主要针对导热硅胶行业,而提供一种作为抗沉降剂的聚硅氧烷对苯二甲酸烯基酯化合物,其通过将对苯二甲酸烯基酯、含氢硅油、铂金催化剂在氮气氛围下发生硅氢加成反应制备得到。本发明提供的聚硅氧烷对苯二甲酸烯基酯化合物,通过酯基与粉体表面、以及酯基之间的相互作用力搭接形成空间网状结构,从而提高导热粉体的分散性和抗沉降性。将其作为抗沉降剂添加在导热有机硅胶体系中,能有效防止有机硅胶在储存过程中发生的沉降现象,且其流动性优良,可保证后期灌封胶的施工效果。(The invention belongs to the field of chemical industry, in particular relates to a production and synthesis technology of an anti-settling agent, and mainly aims at the industry of heat-conducting silica gel to provide a polysiloxane alkenyl terephthalate compound serving as the anti-settling agent, which is prepared by carrying out hydrosilylation on alkenyl terephthalate, hydrogen-containing silicone oil and a platinum catalyst under the nitrogen atmosphere. The polysiloxane alkenyl terephthalate compound provided by the invention forms a spatial network structure by overlapping the ester groups with the surface of the powder and the interaction force between the ester groups, thereby improving the dispersibility and the anti-settling property of the heat-conducting powder. The organic silicon gel is used as an anti-settling agent to be added into a heat-conducting organic silicon gel system, so that the settling phenomenon of the organic silicon gel in the storage process can be effectively prevented, the fluidity is excellent, and the construction effect of the later-stage pouring sealant can be ensured.)

1. A polysiloxane alkenyl terephthalate compound as an anti-settling agent is prepared by the following steps:

(1) putting vinyl alcohol, terephthalic acid, an acid catalyst and toluene into a flask of a Dean-Stark device provided with a stirrer, starting stirring, heating to 100 ℃ and 120 ℃ for reaction until azeotrope is not separated out, naturally cooling to room temperature, adding toluene and a sodium carbonate aqueous solution for washing once, adding deionized water for washing once, adding anhydrous magnesium sulfate for drying, standing for 12 hours, filtering, and carrying out rotary evaporation on a filtrate to obtain vinyl terephthalate;

(2) adding the obtained alkenyl terephthalate, hydrogen-containing silicone oil and a platinum catalyst into a reaction kettle, and carrying out hydrosilylation reaction for 5-6h at 70-90 ℃ in a nitrogen atmosphere to obtain polysiloxane alkenyl terephthalate;

wherein, the acid catalyst is p-toluenesulfonic acid or concentrated sulfuric acid.

2. The polysiloxane alkenyl terephthalate compound of claim 1, wherein the polysiloxane alkenyl terephthalate compound has the general structural formula:

wherein n is more than or equal to 2; r is-CH₂-,-CH₂CH₂-,-CHCH₃-,-CH₂CH₂CH₂-,-CH₂CH₃CH-,-CH₂CH₂CH₃CH-。

3. The polysiloxane alkenyl terephthalate compound of claim 1, wherein the alkenyl alcohol is one of allyl alcohol, 3-butenol, 3-buten-2-ol, 4-pentenol, 4-penten-2-ol, and 1-hexen-3-ol.

4. The polysiloxane alkenyl terephthalate compound of claim 1, wherein the hydrogen-containing silicone oil is a single-ended hydrogen-containing silicone oil having a molecular formula:

HMe₂SiO(SiMe₂O)_mSiMe₃

wherein m is more than or equal to 1.

5. Use of the alkenyl terephthalate polysiloxane compound prepared according to any one of claims 1 to 4 in a heat conductive silicone potting adhesive, a heat conductive silicone grease.

6. A two-component heat conductive silicone potting adhesive comprising the polysiloxane alkenyl terephthalate compound prepared according to any of claims 1-5, comprising the following operations:

the component A comprises: weighing 100 parts of vinyl silicone oil, 1-3 parts of platinum catalyst, 100-200 parts of inorganic heat-conducting filler and 1-3 parts of polysiloxane alkenyl terephthalate compound, and mixing for 10-30min in a high-speed dispersion machine;

and B component: weighing 100 parts of vinyl silicone oil, 100 parts of inorganic heat-conducting filler, 200 parts of hydrogen-containing silicone oil, 0.01-0.05 part of inhibitor and 1-3 parts of polysiloxane alkenyl terephthalate compound, and mixing for 10-30min in a high-speed dispersion machine.

Technical Field

The invention relates to a production and synthesis technology of an anti-settling agent, and provides a polysiloxane alkenyl terephthalate compound as the anti-settling agent mainly aiming at the industry of heat-conducting organic silica gel.

Background

The room temperature vulcanized liquid organic silica gel usually contains solid fillers, such as reinforcing or semi-reinforcing fillers, functional fillers and the like, the solid fillers and oil materials are layered and easily form sedimentation in the natural storage process, so that the oil materials are separated, the fillers cannot be uniformly dispersed in the silica gel, the sedimentation of powder is divided into soft sedimentation and hard sedimentation according to the sedimentation degree, the soft sedimentation is stirred before use, the oil powder can be uniformly mixed again, the curing performance, the bonding performance and other functional performances of the materials cannot be directly influenced, the application cost is increased, and the stability of the application performance of the pouring sealant is not facilitated; and hardening is easily formed by hard sedimentation, and dispersion cannot be realized only by simple stirring, so that even if oil-powder mixing is realized by strong mechanical force, the application performance of the material is influenced, and the construction difficulty is increased. In order to solve the problem of powder sedimentation, an anti-sedimentation agent is usually added to promote the dispersion of filler particles in a liquid phase and prevent the filler from agglomerating and settling, so as to enhance the anti-sedimentation property and anti-caking property of a corresponding system and improve the stability.

At present, the commonly used anti-settling agents are mainly divided into pseudoplastic anti-settling agents and thixotropic anti-settling agents, and the difference between the two is the speed of the system structure recovery after the external shear force is removed. The addition type heat conduction anti-settling silica gel and the preparation method thereof are disclosed in patent No. CN102675882A, the addition type heat conduction anti-settling silica gel adopts gas phase white carbon black, hexamethyldisilazane, distilled water and vinyl silicone oil as anti-settling agents, the obtained addition type heat conduction anti-settling silica gel can be solidified at room temperature or low temperature, the flowing property is excellent, the use is convenient, but the pseudoplastic anti-settling agent has too fast shear recovery and larger viscosity, and can generate adverse effect on the convection level. In order to meet the construction requirements of the organic silicon pouring sealant in the process of encapsulating electronic devices, the pouring sealant needs to have low viscosity and good fluidity so as to ensure smooth encapsulation in products, so that a thixotropic anti-settling agent with relatively slow shear recovery is often selected, the anti-settling performance of a resin part of a pre-filling material is improved, and the viscosity after mixing is reduced to improve the fluidity.

The thixotropic anti-settling agent mainly comprises organic bentonite, polyurea, organic wax and the like, after external shearing force is removed, hydrogen bonds are gradually recovered at a proper speed, and the patent number CN109777344A discloses an anti-settling liquid rheological aid of a bi-component organic silicon pouring sealant and application thereof. The thixotropic settling agent can effectively improve the anti-settling effect of the material, has excellent flowing and leveling properties, mostly forms a network structure through hydrogen bonds in the prior thixotropic settling agent, partially contains N, S and other elements poisoning platinum, and is not suitable for an addition type organic silicon gel system, so that the development of the anti-settling agent for the organic silicon system with new type of bonding force through technical innovation has important significance.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a polysiloxane alkenyl terephthalate compound as an anti-settling agent, which is added into heat-conducting organic silica gel liquid, ester groups are overlapped by virtue of an interaction force to form a space network structure, so that the high viscosity is ensured under low shear to play a role in preventing heat-conducting filler from settling, and the damaged viscosity of the network structure is rapidly reduced under high shear (as shown in figure 1), so that the excellent fluidity of the heat-conducting filler is ensured, the use is convenient, and the problem of filler settling in the organic silica gel is solved.

The invention relates to a polysiloxane alkenyl terephthalate compound as an anti-settling agent, which is prepared by the following steps:

(1) putting vinyl alcohol, terephthalic acid, an acid catalyst and toluene into a flask of a Dean-Stark device provided with a stirrer, starting stirring, heating to 100 ℃ and 120 ℃ for reaction until azeotrope is not separated out, naturally cooling to room temperature, adding toluene and a sodium carbonate aqueous solution for washing once, adding deionized water for washing once, adding anhydrous magnesium sulfate for drying, standing for 12 hours, filtering, and carrying out rotary evaporation on a filtrate to obtain vinyl terephthalate;

(2) adding the obtained alkenyl terephthalate, hydrogen-containing silicone oil and a platinum catalyst into a reaction kettle, and carrying out hydrosilylation reaction for 5-6h at 70-90 ℃ in a nitrogen atmosphere to obtain polysiloxane alkenyl terephthalate;

wherein, the acid catalyst is p-toluenesulfonic acid or concentrated sulfuric acid.

Preferably, the molar ratio of the alkenyl alcohol to the terephthalic acid is 1:0.6 to 1:0.5, the molar ratio of the acid catalyst to the alkenyl alcohol is 0.01:1 to 0.02:1, the volume of the toluene is equal to the volume of the alkenyl alcohol, the molar ratio of the alkenyl terephthalate to the hydrogen-containing silicone oil is 1:0.6 to 1:0.5, and the molar ratio of the alkenyl phthalate to the metal catalyst is 1:0.003 to 1: 0.005.

Preferably, the alkenyl alcohol is one of allyl alcohol, 3-butenol, 3-buten-2-ol, 4-pentenol, 4-penten-2-ol and 1-hexen-3-ol.

Preferably, the hydrogen-containing silicone oil is single-end hydrogen-containing silicone oil, and the molecular structural formula of the hydrogen-containing silicone oil is as follows:

HMe₂SiO(SiMe₂O)_mSiMe₃

wherein m is more than or equal to 1.

The structural general formula of the polysiloxane alkenyl terephthalate compound is as follows:

wherein n is m + 1.

The specific synthetic route of the polysiloxane alkenyl terephthalate compound as the anti-settling agent is as follows:

wherein m is more than or equal to 1; n is m + 1; r is-CH₂-,-CH₂CH₂-,-CHCH₃-,-CH₂CH₂CH₂-,-CH₂CH₃CH-,-CH₂CH₂CH₃CH-。

In the formula I, under the action of an acid catalyst, terephthalic acid and alkenyl alcohol are prepared into alkenyl terephthalate by taking toluene as a water-carrying agent; in the formula II, the prepared alkenyl terephthalate is mixed with single-end hydrogen-containing silicone oil, and polysiloxane alkenyl terephthalate can be obtained under the catalytic action of platinum.

The invention takes polysiloxane terephthalic acid alkenyl ester compound as an anti-settling agent, and comprises polysiloxane chain segments and terephthalic acid alkenyl ester chain segments. Ester groups in the vinyl terephthalate chain segment can be used as anchoring groups to be connected to the surface of the inorganic filler by hydrogen bonds on one hand, and can be mutually overlapped by orientation force to form a space network structure on the other hand, the network structures generate high viscosity under low shearing force to prevent sedimentation, the network structure damage viscosity is rapidly reduced under high shearing force, and the flowability is excellent; the phenyl in the terephthalic acid alkenyl ester chain segment has steric hindrance, so that the rigidity of the high molecular chain in the ester group segment is enhanced, and the dispersion among the powder is facilitated. The polysiloxane segment can be combined with organic resin to improve the dispersibility of inorganic filler in organic resin.

The application of the polysiloxane alkenyl terephthalate compound prepared by the technical method in the heat-conducting organic silica gel liquid. The two-component heat-conducting organic silicon pouring sealant containing the polysiloxane alkenyl terephthalate compound prepared by the technical scheme specifically comprises the following operations:

the component A comprises: weighing 100 parts of vinyl silicone oil, 1-3 parts of platinum catalyst, 100-200 parts of inorganic heat-conducting filler and 1-3 parts of polysiloxane alkenyl terephthalate compound, and mixing for 10-30min in a high-speed dispersion machine;

and B component: weighing 100 parts of vinyl silicone oil, 100 parts of inorganic heat-conducting filler, 200 parts of hydrogen-containing silicone oil, 0.01-0.05 part of inhibitor and 1-3 parts of polysiloxane alkenyl terephthalate compound, and mixing for 10-30min in a high-speed dispersion machine;

curing the heat-conducting organic silicon pouring sealant: a, B components are uniformly mixed according to equal mass parts, and the mixture is defoamed in a vacuum defoaming machine for 5 to 10 minutes to obtain the heat-conducting organic silica gel.

Wherein the inorganic heat-conducting filler is one or more of aluminum oxide, magnesium oxide, zinc oxide, silicon micropowder and aluminum nitride, and the median diameter D50 of the heat-conducting filler is 1-50 μm.

Compared with the prior art, the invention has the following advantages:

(1) different from the currently common organic polymer anti-settling agent, the polysiloxane alkenyl terephthalate anti-settling agent prepared by the invention does not contain N, S and other platinum poisoning elements, so that the problems of incomplete curing and no curing after the anti-settling agent is added in an organic silicon system are avoided;

(2) compared with the currently common inorganic anti-settling agent, the anti-settling agent provided by the invention contains a novel ester group type bonding force, the ester groups are mutually overlapped to form a network structure to prevent powder from settling, but the orientation force between the ester groups is weaker than a hydrogen bond, and the formed network structure is easier to break under the action of external shearing force, so that the shaking effect is easier to achieve;

(3) compared with the conventional anti-settling agent, the polysiloxane chain segment at one end of the polysiloxane alkenyl terephthalate can be combined with organic resin, so that the compatibility of inorganic filler and organic resin is improved, and the polysiloxane alkenyl terephthalate plays a role of a dispersing agent;

(4) the polysiloxane alkenyl terephthalate provided by the invention is added in the heat-conducting organic silicon pouring sealant as an anti-settling agent, so that the problem that powder oil is layered and bottom cake is formed due to the introduction of a large amount of heat-conducting filler is avoided, the anti-settling property of powder is effectively improved, the pouring sealant after mixing is low in viscosity and excellent in fluidity, and the construction requirement of the product during pouring is met.

Drawings

FIG. 1 is a graph of the data of the viscosity test of example 1 at the rotation speed of 6r/min and 60 r/min.

Detailed Description

The technical features of the technical solutions provided by the present invention are further clearly and completely described below with reference to the following embodiments, which are not intended to limit the scope of protection thereof.

Example 1

Preparation of anti-settling agent: (1) to a vessel equipped with a stirrerAdding 13.6mL of allyl alcohol, 16.6g of terephthalic acid, 1.06mL of concentrated sulfuric acid and 13.6mL of methylbenzene into a flask of a Dean-Stark device, heating to 120 ℃, stirring at a rotating speed of 50r/min for reacting for 2h to obtain a product, washing with sodium carbonate for 3 times, drying, and distilling and purifying again to obtain diallyl terephthalate; (2) 11.7g of diallyl terephthalate, 26g of HMe₂SiO(SiMe₂O)₂SiMe₃Hydrogen-containing silicone oil and 0.23g of platinum catalyst are added into a pressure-resistant stainless steel reactor and reacted for 5 hours at 80 ℃ in a nitrogen atmosphere to obtain polysiloxane diallyl terephthalate.

Example 2

Preparation of anti-settling agent: (1) adding 16.8mL of methyl allyl alcohol, 16.6g of terephthalic acid, 5.55mL of p-toluenesulfonic acid and 16.8mL of toluene into a flask of a Dean-Stark device with a stirrer, heating to 100 ℃, stirring at a rotating speed of 50r/min for reaction for 3h to obtain a product, washing with sodium carbonate for 3 times, drying, and distilling and purifying again to obtain the dimethyl propylene terephthalate; (2) 13.4g of dimethyl propylene terephthalate and 26g of HMe₂SiO(SiMe₂O)₂SiMe₃Adding hydrogen-containing silicone oil and 0.19g of platinum catalyst into a pressure-resistant stainless steel reactor, and reacting for 5 hours at 70 ℃ in a nitrogen atmosphere to obtain polysiloxane dimethyl propylene terephthalate.

Comparative example 1

Comparative example 1 differs from example 1 in that a polysiloxane diallyl cyclohexanedicarboxylate anti-settling agent was prepared using an equimolar amount of 1, 4-cyclohexanedicarboxylic acid instead of terephthalic acid.

Example 3

Preparing heat-conducting organic silica gel liquid:

(1) 100 parts of vinyl silicone oil (5000mPa · s, containing vinyl 0.40%), 1 part of platinum catalyst, 150 parts of alumina, 50 parts of magnesium oxide, 2 parts of the anti-settling agent prepared in example 1 were mixed in a high-speed disperser for 20min to obtain component A;

(2) 100 parts of vinyl silicone oil (5000 mPas, containing vinyl groups 0.40%), 150 parts of alumina, 50 parts of magnesium oxide, 4 parts of hydrogen-containing silicone oil (150 mPas, containing hydrogen 0.18%), 0.03 part of inhibitor, and 2 parts of the anti-settling agent prepared in example 1 were mixed in a high-speed disperser for 20min to obtain component B;

(3) curing the glue solution: and adding 100 parts of the component A and 100 parts of the component B into a mixer, mixing for 10min at the rotating speed of 600r/min, and defoaming for 10min in a vacuum defoaming machine to obtain the heat-conducting organic silica gel.

Example 4

Example 4 differs from example 3 in that the anti-settling agent is exchanged for an equal mass of the anti-settling agent prepared in example 2.

Examples 5 to 7

Examples 5-7 differ from example 3 in that the amount of anti-settling agent was reduced to 1/2, 1/5, 1/10, respectively.

Comparative example 2

Comparative example 2 differs from example 3 in that the anti-settling agent is exchanged for an equal mass of the anti-settling agent prepared in comparative example 1.

Comparative example 3

Comparative example 3 differs from example 3 in that no anti-settling agent is added.

80mL of the thermally conductive silicone rubber prepared in each of examples 3 to 7 and comparative examples 2 to 3 was placed in a 100mL measuring cylinder, placed in a shady and ventilated place and left to stand for 120 days, and the heights of the supernatants were measured at 30 days, 60 days, and 120 days, respectively, and the results are shown in Table 1.

TABLE 1

	Day 30	Day 60	Day 120
				Example 3	0	0	0
Example 4	0	0	0
				Example 5	0	1	3
Example 6	3	4	6
				Example 7	5	9	13
Comparative example 2	5	10	18
				Comparative example 3	15	27	32

As can be seen from Table 1, the supernatant heights of examples 3 and 4 after 120 days were 32 lower than that of comparative example 3 without the anti-settling agent and 18 lower than that of comparative example 2 using the polysiloxane diallyl cyclohexanedicarboxylate anti-settling agent, and the anti-settling agent of the present invention was substantially free of delamination after standing for a long time and was excellent in anti-settling effect; the heights of the supernatants of examples 5-7 increased progressively with decreasing amounts of anti-settling agent compared to example 3, indicating that the anti-settling properties of the invention become increasingly poorer with decreasing amounts of anti-settling agent.

The performance test methods of examples and comparative examples are as follows:

the thermally conductive silicone rubbers prepared in examples 3 to 7 and comparative examples 2 to 3 were cured at room temperature at 25 ℃ for 12 hours, respectively, and the viscosity was measured at 25 ℃ using a rotational viscometer (NDJ-8S digital display rotational viscometer) and a B-type viscometer (BHII type viscometer), and the test data was recorded at 6r/min and 60r/min, and the viscosity measured at 60r/min as the viscosity ratio at 6r/min was used as the thixotropic ratio, and the results are shown in Table 2. Testing the heat conductivity coefficient of the cured silica gel composition by using a DRL-III heat conductivity coefficient tester, wherein the diameter of a sample is 20mm, and the thickness of the sample is 2 mm; measuring the hardness of the silica gel cured material by using a rubber hardness tester (LX-A type), wherein the hardness refers to GB/T531-2008; tensile strength and elongation at break of the cured silica gel were measured by a tensile tester (model ZwickZ 010) and the results are shown in Table 3, with reference to GB/T528-1998.

TABLE 2

The thixotropic ratio in Table 2 is a ratio of the viscosity at 6r/min to the viscosity at 60r/min, and is used to characterize how easily it is changed from a viscous state to a fluid state by shearing. From the table, it can be observed that the thixotropic ratio of example 3 is 3.57, which is higher than that of examples 5-7, indicating that the gel is more easily changed from a viscous state to a fluid state with an increase in the amount of the anti-settling agent added under the same shearing force; similarly, the thixotropic ratios of comparative example 2 to which other anti-settling agent is added and comparative example 3 to which no anti-settling agent is added are 1.86 and 1.17 in this order, which are lower than those of example 3, indicating that the colloid to which the anti-settling agent of the present invention is added is more likely to change from a viscous state to a fluid state under shear.

TABLE 3

As can be seen from Table 3, in example 3 of the present invention, compared with the comparative example, the hardness and tensile strength of the product are significantly better than those of the comparative example, as is example 4, and the defect of the sedimentation of the heat conductive filler during the storage of the heat conductive silicone rubber can be solved.

The above embodiments are merely examples for clearly illustrating the present invention and do not limit the present invention. Other variants and modifications of the invention, which are obvious to those skilled in the art and can be made on the basis of the above description, are not necessary or exhaustive for all embodiments, and are therefore within the scope of the invention.