阅读说明：本技术 一种有机硅柔性包封材料及其制备方法和用途 (Flexible organic silicon encapsulating material and preparation method and application thereof ) 是由 罗兴成 吴先鹏 刘旭 李富强 李强 唐玲 张程夕 陶云峰 于 2020-05-14 设计创作，主要内容包括：本发明涉及一种有机硅柔性包封材料及其制备方法和用途,尤其用于PTC限流片的包封材料。本发明的有机硅柔性包封材料包括乙烯基聚硅氧烷、氢基聚硅氧烷、增粘剂、催化剂、功能填料、处理剂、色母料、稀释剂等组分。本发明的材料使用过程满足现有硅树脂材料施工工艺,包封的PTC限流片产品电性能优异,耐高低温冲击,耐通断测试。包封的PTC限流片能应用于电机启动、PTC加热器启动等存在较大冲流的场合,包封的焊接型PTC启动器产品能完全替代壳体类PTC启动器。(The invention relates to an organic silicon flexible encapsulating material, a preparation method and application thereof, in particular to an encapsulating material for a PTC flow-limiting sheet. The flexible organosilicon encapsulating material comprises vinyl polysiloxane, hydrogen polysiloxane, a tackifier, a catalyst, a functional filler, a treating agent, a color masterbatch, a diluent and the like. The use process of the material meets the requirements of the existing silicone resin material construction process, and the encapsulated PTC current limiting sheet product has excellent electrical property, high and low temperature impact resistance and on-off test resistance. The encapsulated PTC current-limiting sheet can be applied to occasions with large rush current such as motor starting, PTC heater starting and the like, and the encapsulated welding type PTC starter product can completely replace a shell type PTC starter.)

1. A flexible organosilicon encapsulating material comprises the following components in parts by weight:

(a) 100 parts of vinyl-containing polysiloxane;

(b) 1-12 parts of a tackifier, preferably 2-10 parts;

(c) 3-15 parts of hydrogen-containing polysiloxane, preferably 4-12 parts;

(d) 0.025-0.1 part of catalyst, preferably 0.04-0.08 part;

(e) 50-150 parts of functional filler, preferably 110-145 parts;

(f) 0.5-5 parts of treating agent, preferably 1-3 parts;

(g) 0-18 parts of color masterbatch, preferably 1-15 parts;

(h) 18-80 parts of diluent, preferably 20-70 parts;

(i) 0.007 to 0.2 part of polymerization inhibitor, preferably 0.01 to 0.1 part.

2. The flexible silicone encapsulating material according to claim 1, wherein the vinyl-containing polysiloxane (a) is a polysiloxane containing terminal vinyl groups or terminal vinyl groups, and the vinyl-containing polysiloxane has a viscosity at 25 ℃ in the range of 100 to 300000mpa.s, preferably a viscosity at 25 ℃ in the range of 1500 to 50000mpa.s (viscosity test according to the standard GB/T10247 rotational viscometer method), and preferably has a specific molecular structure as shown in formula (I):

wherein Vi represents vinyl, m is an integer of 50-10000, n is an integer not less than 0, and (m + n) makes the viscosity of the vinyl polysiloxane (a) meet the requirement of 100-300000 mPa.s at room temperature of 25 ℃; when n is 0, the vinyl polysiloxane represented by (I) is a terminal vinyl polysiloxane, and when n is an integer > 0, the vinyl polysiloxane represented by (I) is a terminal vinyl polysiloxane, and n is preferably such that the vinyl content of the vinyl polysiloxane (a) is 0.01 to 3 wt%.

3. The flexible silicone encapsulating material according to claim 1 or 2, wherein the tackifier (b) is one or more reactive oligomers containing epoxy functional groups, such as siloxane ring bodies or oligomers containing a silicon-hydrogen structure (such as tetramethylcyclotetrasiloxane) and oligomers obtained by hydrosilylation reaction of monomers containing double bonds and epoxy functional groups (such as allyl glycidyl ether) under the action of platinum catalyst, Allyl Glycidyl Ether (AGE), 3- (2, 3-epoxypropoxy) propyltrimethoxysilane and 3- (methacryloyloxy) propyltrimethoxysilane.

4. The flexible organosilicon encapsulating material according to any one of claims 1 to 3, wherein the hydrogenpolysiloxane (c) is selected from a functional hydrogenpolysiloxane terminated with trimethylsilyl groups and uniformly distributed side hydrogen or a functional hydrogenpolysiloxane containing hydrogen at end side, the viscosity is 20 to 200mPa.s at room temperature of 25 ℃, and the hydrogen content is 0.15 to 1 wt%;

preferably, the molecular structure of the hydrogenpolysiloxane is shown as formula (II):

wherein R is₂Is methyl or hydrogen, x is more than or equal to 0, y is more than 0, wherein x + y is satisfied to make the viscosity of the hydrogenpolysiloxane (II) at room temperature and 25 ℃ be 20-200 mPa.s, and y is satisfied to make the hydrogen content of the hydrogenpolysiloxane (II) be 0.15-1 wt%.

5. The flexible silicone encapsulant according to any of claims 1-4, characterised in that catalyst (d) is a compound containing platinum, rhodium, ruthenium, palladium metal elements or a complex thereof, preferably a platinum-containing compound or complex, more preferably chloroplatinic acid or a complex of chloroplatinic acid with a vinyl-containing compound, for example a complex of chloroplatinic acid with 1, 3-divinyl-1, 1,3, 3-tetramethyldisiloxane (Karstedt catalyst).

6. The flexible organosilicon encapsulating material according to any of claims 1 to 5, wherein the functional filler (e) is selected from one or more of quartz, talc, mica powder, alumina, fumed silica, preferably from quartz with a median diameter D50 of 0.2 to 25 μm, mica powder, alumina, a specific surface area (according to BET method) of 100 to 400m²Per g, preferably 150 to 380m²One or more of fumed silica per gram;

preferably, the e) functional filler comprises:

e1) quartz with a median diameter of 0.2-20 μm;

e2) talcum powder with a median diameter of 0.2-25 mu m;

e3) mica powder with the median diameter of 0.2-25 mu m;

e4) the specific surface area is 200-380 m²(ii) fumed silica per gram;

e5) alumina with a median diameter of 1-15 μm;

the functional filler comprises the following components in parts by weight:

e1) 0 to 55 parts, preferably 5 to 30 parts;

e2) 0 to 120 parts, preferably 5 to 105 parts;

e3) 0 to 70 parts, preferably 5 to 65 parts;

e4) 0 to 40 parts, preferably 5 to 30 parts;

e5) is 0 to 50 parts, preferably 5 to 40 parts.

7. A silicone flexible encapsulant according to any of claims 1-6, characterized in that treatment agent (f) is selected from one or more of methyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, hexamethyldisilazane, octyltriethoxysilane, dodecyltrimethoxysilane and the like.

8. The flexible silicone encapsulant according to any of claims 1-7, wherein diluent (h) is a good solvent for silicone, preferably selected from one or more of xylene, toluene, solvent gasoline, n-hexane, petroleum ether; and/or

The polymerization inhibitor is an alkynol compound, such as 1-ethynyl cyclohexanol.

9. The method for preparing the flexible encapsulating material of silicone as claimed in any one of claims 1 to 8, comprising the steps of:

(A) preparation of sizing material

Adding the functional filler (e), the vinyl polysiloxane (a) and the treating agent (f) into a mixing device such as a kneader and the like, heating to 80-100 ℃, preferably 85-95 ℃ for sizing, uniformly stirring, treating for 1-6 h to obtain a basic sizing, continuously heating to 110-130 ℃, drying (such as vacuum drying for 2-4 h), cooling and grinding;

(B) glue preparation

Adding the basic rubber material into a rubber preparation container, adding the catalyst (d), the tackifier (b), the hydrogen-containing polysiloxane (c), the color master batch (g), the diluent (h) and the polymerization inhibitor (i), and uniformly stirring.

10. Use of a silicone flexible encapsulant material as claimed in any of claims 1-8 for encapsulation of PTC flow-restriction sheets.

Technical Field

The invention relates to an organic silicon flexible encapsulating material, a preparation method and application thereof, in particular to the technical field of encapsulating materials for PTC current-limiting sheets.

Background

PTC is a thermistor with positive temperature coefficient, and its main application can be divided into switching and heating.

The PTC material has the switching characteristics of heat sensitivity, current limitation, time delay and the like, and the characteristics of no contact, no noise and long service life, and can be applied to small household appliances such as refrigerator starting, motor transformer protection, stored program control switch protection, mosquito dispeller, hair curler, electric iron and the like.

Various heater products manufactured by utilizing the characteristics of stable performance, rapid temperature rise, small influence of power supply voltage fluctuation and the like of heating PTC are widely applied to heaters, clothes dryers, air curtains, air conditioners and the like at present.

A PTC thermistor is a semiconductor resistor typically having temperature sensitivity, and its resistance value increases stepwise with an increase in temperature (curie temperature) beyond a certain temperature. The change of the temperature of the PTC thermistor body can be obtained by the current flowing through the PTC thermistor, or by the external input of heat, or by the superposition of the two.

The PTC current-limiting sheet is generally encapsulated by silicone resin and epoxy resin, and the encapsulated current-limiting element can only be used in occasions with low overall current of a line and low heat generation during operation.

For the scenes that high current impact exists in the starting of a servo motor, the starting of a PTC heater of an air conditioner and the like, a shell type PTC current-limiting starter is generally used. If the conventional encapsulated type PTC current limiting starter is used, there are the following problems:

(1) the traditional encapsulating material cannot resist high and low temperature impact, and the encapsulating layer cracks and pulverizes under the high and low temperature impact.

(2) And the PTC current-limiting sheet encapsulated by the traditional material is aged, and the conditions of cracking of an encapsulating layer and poor external insulation occur after short-term on-off test.

(3) The PTC current-limiting sheet encapsulated by the traditional material has low external insulation strength, and cannot meet the requirement that the external insulation strength of the current-limiting sheet is higher than 1500V.

Compared with the encapsulated PTC current-limiting starter and the shell type PTC current-limiting starter, the encapsulated PTC current-limiting starter has the following advantages:

(1) the structure is simple, the semi-automatic production can be carried out in batches, the production efficiency is high, and the cost is low.

(2) Good heat dissipation and fast response speed.

(3) The product is small in size, and the use space of the circuit is reduced.

(4) Reduce overall power consumption.

Although the encapsulated PTC current-limiting starter has more advantages, the encapsulated PTC current-limiting starter has poor reliability due to the limitation of the conventional encapsulating material, and cannot be used in batches.

Disclosure of Invention

Aiming at the problems that the traditional encapsulating material cannot meet the requirements of large-current multiple impact, high-low temperature impact resistance and the like, the invention develops a high-performance PTC current-limiting sheet encapsulating material which is composed of organosilicon flexible chain segments, is high-low temperature impact resistant and has excellent external insulation performance. The PTC current-limiting sheet encapsulated by the material has the external insulation voltage higher than 1500V, impacts thousands of times (-40-120 ℃) at high and low temperatures, has no obvious change in the performance of the elements in on-off test, and can completely replace a shell PTC current-limiting starter.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a flexible organosilicon encapsulating material comprises the following components in parts by weight:

(a) 100 parts of vinyl-containing polysiloxane;

(b) 1-12 parts of a tackifier, preferably 2-10 parts;

(c) 3-15 parts of hydrogen-containing polysiloxane, preferably 4-12 parts;

(d) 0.025-0.1 part of catalyst, preferably 0.04-0.08 part;

(e) 50-150 parts of functional filler, preferably 110-145 parts;

(f) 0.5-5 parts of treating agent, preferably 1-3 parts;

(g) 0-18 parts of color masterbatch, preferably 1-15 parts;

(h) 18-80 parts of diluent, preferably 20-70 parts;

(i) 0.007 to 0.2 part of polymerization inhibitor, preferably 0.01 to 0.1 part.

Furthermore, the vinyl polysiloxane (a) is polysiloxane with terminal vinyl or terminal vinyl, the viscosity range at 25 ℃ is 100-300000 mPa.s, preferably vinyl polysiloxane with viscosity at 25 ℃ of 1500-50000 mPa.s (viscosity test is according to standard GB/T10247 rotational viscometer method), and the specific molecular structure is shown as (I).

Wherein Vi represents a vinyl group, m is an integer of 50 to 10000, n is an integer of 0 or more, and the viscosity of the vinylpolysiloxane (m + n) is preferably such that the viscosity of the vinylpolysiloxane (a) at room temperature of 25 ℃ satisfies the requirement of 100 to 300000mPa.s, the larger the m + n is, the larger the viscosity becomes. When n is 0, the vinyl polysiloxane represented by (I) is a terminal vinyl polysiloxane, and when n is an integer > 0, the vinyl polysiloxane represented by (I) is a terminal vinyl polysiloxane, and n is preferably such that the vinyl content of the vinyl polysiloxane (a) is 0.01 to 3 wt%.

The vinyl polysiloxane (a) can be prepared by equilibrium reaction of siloxane ring containing methyl vinyl group, dimethyl siloxane ring and vinyl double head under the catalyst of basic silicon alkoxide, and can be one or more of V-300, V-500, V-1000, V-1500, V-5000, V-15000, V-20000 and V-60000, produced by Jiangsu Happy New materials Co., Ltd, Andisil VS100, Andisil VS200, Andisil VS500, Andisil VS1000, Andisil VS5000, Andisil VS10000, Andisil VS20000 and Andisil VS165000, produced by AB Specialty Silicones (Nantong) Co., L td.

Further, the tackifier (b) is a reactive oligomer containing epoxy functional groups, such as the tackifier with the structure described in chinese patent CN104694004A, and the preparation method of the tackifier can be obtained by hydrosilylation reaction of siloxane ring or oligomer containing silicon-hydrogen structure (such as tetramethylcyclotetrasiloxane) and monomer containing double bonds and epoxy functional groups (such as allyl glycidyl ether) under the action of platinum catalyst. Other adhesion promoters may be Allyl Glycidyl Ether (AGE) available from Profenov technologies, Inc., 3- (2, 3-glycidoxy) propyl trimethoxysilane (KH-560) available from Jiangxi Chenguang New materials, Inc., 3- (methacryloyloxy) propyl trimethoxysilane (KH-570), and Dowsil (Dowsil) as additives for promoting adhesion of addition type release agentsS L9250 and the like.

Further, the hydrogen-containing polysiloxane (c) includes a functional hydrogen-containing polysiloxane terminated with trimethylsilyl groups and uniformly distributed side hydrogen or a polysiloxane containing hydrogen at the end side. Under the condition of room temperature of 25 ℃, the viscosity is 20 to 200mPa.s, and the hydrogen content is 0.15 to 1 wt%.

The specific molecular structure of the hydrogenpolysiloxane is shown as (II):

wherein R is₂Is methyl or hydrogen, x is more than or equal to 0, y is more than 0, wherein x + y is satisfied to make the viscosity of the hydrogenpolysiloxane (II) at room temperature and 25 ℃ meet 20-200 mPa.s, and y is satisfied to make the hydrogenpolysiloxane (II) meet(II) has a hydrogen content of 0.15 to 1 wt%.

The preparation method of hydrogen-containing polysiloxane (c) is well known in the industry, and polymethyl (hydrogen) siloxane with high hydrogen content and dimethyl siloxane ring body are obtained by equilibrium reaction under the action of acid catalyst such as cation resin, trifluoromethanesulfonic acid and the like, commercially available hydrogen-containing polysiloxane is one or more of SH-18, SH-25, SH-36, SH-50, SH-75, DSH-100, DSH-28 and the like, and one or more of Andisil X L-1B, Andisil X L-10, Andisil X L-11, Andisil X L-12, Andisil X L-13, Andisil X L-1340, Andisil X L-1341 and Andisil X L-1342 which are produced by Jiangsu Ke Hakkoni, Nguchi, Nashiki, and the like.

Further, the catalyst (d) is a compound containing a metal element such as platinum, rhodium, ruthenium, palladium or the like or a complex thereof, and preferably a compound or a complex containing platinum, such as chloroplatinic acid or a complex of chloroplatinic acid and a vinyl-containing compound, or the like. The most preferred catalyst is the complex of chloroplatinic acid with 1, 3-divinyl-1, 1,3, 3-tetramethyldisiloxane (Karstedt catalyst). Commercial Karstedt catalysts may be selected from Pt-5000 by Shanghai Heley Industrial technology materials, Inc. and Pt-5000 by Guimo platinum industries, Inc. In both catalysts, the Pt content was 5000 ppm.

Further, the functional filler (e) is selected from one or more of quartz, talc powder, mica powder, alumina, fumed silica, and the like. When the functional filler is inorganic powder such as quartz, mica powder, alumina and the like, the particle size range of the functional filler is that the median diameter D50 is 0.2-25 mu m; when the functional filler is fumed silica, the specific surface area (according to BET method) is preferably 100 to 400m²Per g, preferably 150 to 380m²/g。

In a preferred embodiment, the e) functional filler comprises:

e1) quartz with a median diameter of 0.2-20 μm;

e2) talcum powder with a median diameter of 0.2-25 mu m;

e3) mica powder with the median diameter of 0.2-25 mu m;

e4) the specific surface area is 200-380 m²Perg fumed silica；

e5) Alumina with a median diameter of 1-15 μm.

In the technical scheme, the functional filler comprises the following components in parts by weight:

e1) 0 to 55 parts, preferably 5 to 30 parts;

e2) 0 to 120 parts, preferably 5 to 105 parts;

e3) 0 to 70 parts, preferably 5 to 65 parts;

e4) 0 to 40 parts, preferably 5 to 30 parts;

e5) is 0 to 50 parts, preferably 5 to 40 parts.

Further, the treating agent (f) is mainly a treating agent (coupling agent) for powder surface modification, and may be, for example, one or more selected from methyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, hexamethyldisilazane, octyltriethoxysilane, dodecyltrimethoxysilane, and the like.

Preferably, the color masterbatch (g) is a homogeneous mixture of a pigment or dye and a vinyl-terminated polysiloxane prepared in a certain ratio. The preparation method can be used for preparing the vinyl-terminated polysiloxane by mixing organic or inorganic pigments, organic dyes and the like with vinyl-terminated polysiloxane with the viscosity of 100-1000 mPa.s at room temperature according to a certain proportion and grinding the mixture by three rollers. The organic or inorganic pigment and dye includes carbon black, titanium dioxide, iron oxide red, iron yellow, iron black, phthalocyanine blue, phthalocyanine green, etc.

Commercially available color masterbatch (g) can be selected from one or more of carbon black masterbatch SM-001, iron red masterbatch SM-003, phthalocyanine green masterbatch SM-007 and iron yellow masterbatch SM-008 which are produced by Dutuoli science and technology Limited.

Preferably, the diluent (h) is a good solvent of organosilicon, and can be one or more selected from xylene, toluene, solvent gasoline, n-hexane and petroleum ether.

In the technical scheme, the catalyst can further comprise a polymerization inhibitor (i); the polymerization inhibitor is preferably 0.01-0.1 part by weight; the polymerization inhibitor is preferably an alkynol compound, such as 1-ethynylcyclohexanol.

According to a second aspect of the present invention, there is provided a method for preparing the silicone flexible encapsulating material, comprising the following steps;

in the above technical scheme, the functional filler is a pretreated filler, and the pretreatment process of the functional filler is as follows:

(A) preparation of sizing material

Adding the functional filler (e), the vinyl polysiloxane (a) and the treating agent (f) into a mixing device such as a kneader, heating to 80-100 ℃, preferably 85-95 ℃ for sizing, uniformly stirring, treating for 1-6 h to obtain a basic sizing, continuously heating to 110-130 ℃, drying (for example, vacuum drying for 2-4 h), cooling and grinding.

(B) Glue preparation

Adding the basic rubber material into a rubber preparation container, adding the catalyst (d), the tackifier (b), the hydrogen-containing polysiloxane (c), the color master batch (g), the diluent (h) and the polymerization inhibitor (i), and uniformly stirring.

According to a third aspect of the invention, the use of the silicone flexible encapsulating material for encapsulating the PTC current-limiting sheet is provided, and particularly the encapsulating of the PTC current-limiting element of the circuit with rush current and frequent starting is carried out, so that the encapsulating material has the functions of insulation, heat dissipation, moisture prevention and prolonging the service life of the element. The PTC current-limiting element encapsulated by the high-performance material can be used for a rush current circuit with larger circuit total current, such as the current-limiting protection of rush current when an air conditioner heating system is started, the current-limiting protection of motor start, and the current-limiting protection of the rush current circuit with larger circuit total current or the overheat protection of a specific occasion.

THE ADVANTAGES OF THE PRESENT INVENTION

The invention adopts silicon rubber as a basic polymer, and functional filler and auxiliary agent are added to prepare the material for encapsulating the PTC restrictor plate. The use process of the material meets the requirements of the existing silicone resin construction process, and the encapsulated PTC current limiting sheet product has excellent electrical property, high and low temperature impact resistance and on-off test resistance. The encapsulated PTC current-limiting sheet can be applied to occasions with large rush current such as motor starting, PTC heater starting and the like, and the encapsulated welding type PTC starter product can completely replace a shell type PTC starter.

Detailed Description

The invention is further illustrated by the following specific examples.