Single-component epoxy adhesive for thermosensitive component and preparation and use method of single-component epoxy adhesive

Abstract

The invention relates to the technical field of packaging materials for electrical components, and discloses a single-component epoxy adhesive for thermosensitive components, which comprises the following components: 5-25 parts by mass of flexible resin; 1-5 parts by mass of high-temperature-resistant resin; 30-50 parts by mass of epoxy resin; 0-5 parts by mass of a pigment; 0-3 parts by mass of an additive; 30-50 parts by mass of a filler; 0-3 parts by mass of a rheological aid; and 5-15 parts by mass of a curing agent. The invention also discloses a preparation and use method of the single-component epoxy adhesive. The adhesive provided by the invention is moderate in viscosity, and a formed adhesive cured product is high-temperature-resistant and high in insulating strength.

Description

Technical Field

[0001] This invention relates to the field of electrical component packaging materials, and in particular to a one-component epoxy adhesive for thermal components and its preparation and application method. Background Technology

[0002] Both PPTC and PTC are positive temperature coefficient thermistors, but the difference lies in their operating conditions: PPTC operates with high current and low voltage, while PTC operates with low current and high voltage. PTC is a new type of overcurrent and overtemperature protection device, essentially a resettable fuse, providing overcurrent and overtemperature protection. Based on manufacturing materials, it can be divided into organic polymer PPTC and ceramic PTC. In contrast to PTC, NTC thermistors have resistance that decreases with increasing temperature and can be used for surge suppression and temperature measurement.

[0003] To protect thermal components, adhesives are needed to provide waterproofing and insulation. However, existing adhesives are not heat-resistant and are prone to cracking after reflow soldering (240-260℃ for 10 minutes). They fail to provide adequate waterproofing and insulation, leading to the failure of thermal components and consequently increasing the risk of electronic product malfunctions.

[0004] Chinese patent "Epoxy Acrylic Polymer Mixture for NTC Temperature Sensor Encapsulation and its Preparation Process" (Publication No.: CN121203352A) discloses an epoxy acrylate polymer mixture that enables the temperature sensor to withstand temperatures up to 200°C. The resin encapsulates the sensor through a multi-stage curing process involving UV curing and thermal curing. However, the high-temperature resistance of the encapsulation layer is not ideal, and the curing process is complex. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide a single-component epoxy adhesive for thermal components and its preparation and use method. The adhesive has a moderate viscosity and the cured adhesive has high temperature resistance and high insulation strength.

[0006] The technical solution adopted in this invention is:

[0007] A one-component epoxy adhesive for thermal components, characterized in that it comprises the following components: 5-25 parts by weight of flexible resin; 1-5 parts by weight of high-temperature resistant resin; 30-50 parts by weight of epoxy resin; 0-5 parts by weight of pigment; 0-3 parts by weight of additive; 30-50 parts by weight of filler; 0-3 parts by weight of rheology modifier; and 5-15 parts by weight of curing agent.

[0008] Furthermore, the flexible resin is one or more of core-shell modified epoxy resin, rubber modified epoxy resin, and sulfur rubber modified epoxy resin.

[0009] The high-temperature resistant resin is one or more of the following: phenolic modified epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, multifunctional epoxy resin, and naphthalene ring epoxy resin.

[0010] The epoxy resin is one or both of bisphenol A epoxy resin and bisphenol F epoxy resin;

[0011] The pigment is one or more of the following: red, yellow, blue, white, and black;

[0012] The additive is one or both of organosilicon defoamers and silane coupling agents;

[0013] The filler is one or both of alumina and silica powder;

[0014] The rheology modifier is one or two of thixotropic rheology modifiers and fumed silica;

[0015] The curing agent is one or two of imidazole adducts, tertiary amine adducts, and modified amine curing agents.

[0016] Furthermore, the thermistor is a PTC, PPTC, or NTC.

[0017] A method for preparing a one-component epoxy adhesive for thermal components, characterized in that,

[0018] Includes the following steps,

[0019] (a) Add flexible resin, high temperature resistant resin, epoxy resin, pigment and additives to the mixing tank in the order of the mass parts of each component, and stir for 30 to 60 minutes.

[0020] (b) Add the filler and rheology modifier in the order of mass parts, and stir for 2 hours;

[0021] (c) Then cool to below 40°C;

[0022] (d) Add the curing agent according to the mass fraction, stir for 10 minutes, and keep the temperature below 40℃;

[0023] (e) Disperse the product five times using a three-roll mill, keeping the temperature below 40°C;

[0024] (f) Stir for 10 minutes, keeping the temperature below 40°C;

[0025] (g) Vacuum degassing for 60 minutes;

[0026] (h) The single-component epoxy adhesive is obtained.

[0027] A method for using a one-component epoxy adhesive for thermal components, characterized in that the one-component epoxy adhesive is coated or screen-printed onto the thermal component and cured at 90°C to 120°C for 20-60 minutes to form a cured one-component epoxy adhesive.

[0028] The beneficial effects of this invention are:

[0029] (1) The epoxy adhesive of this patent is environmentally friendly and meets the halogen-free standard: total chlorine ≤ 900 ppm, total bromine ≤ 900 ppm, total chlorine + bromine ≤ 1500 ppm;

[0030] (2) The adhesive is resistant to high temperature after curing and does not crack after being reflowed at a high temperature of 240-260℃ for 10 minutes;

[0031] (3) It has the characteristics of high insulation strength and low water absorption, which protects the thermal components very well;

[0032] (4) The adhesive has a moderate viscosity, which is suitable for coating and screen printing to cover thermal components. Detailed Implementation

[0033] The following is a detailed description of the specific implementation of a single-component epoxy adhesive for thermal components and its preparation and application method according to the present invention.

[0034] The present invention discloses a formulation for a high-temperature resistant single-component epoxy adhesive for thermal components, which is applied to thermal components (PTC, PPTC, NTC) to protect the thermal components.

[0035] The adhesive is a single-component adhesive, comprising the following components: 5-25 parts by weight of flexible resin; 1-5 parts by weight of high-temperature resistant resin; 30-50 parts by weight of epoxy resin; 0-5 parts by weight of pigment; 0-3 parts by weight of additive; 30-50 parts by weight of filler; 0-3 parts by weight of rheology modifier; and 5-15 parts by weight of curing agent.

[0036] in,

[0037] The flexible resin is one or more of the following: core-shell modified epoxy resin, rubber modified epoxy resin, and sulfur rubber modified epoxy resin.

[0038] The high-temperature resistant resin is one or more of the following: phenolic modified epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, multifunctional epoxy resin, and naphthalene ring epoxy resin.

[0039] The epoxy resin is one or both of bisphenol A epoxy resin and bisphenol F epoxy resin;

[0040] The pigment is one or more of the following: red, yellow, blue, white, and black;

[0041] The additive is one or both of the following: organosilicon defoamer and silane coupling agent;

[0042] The filler is one or both of alumina and silica powder;

[0043] The rheology modifier is one or two of thixotropic rheology modifiers and fumed silica.

[0044] The curing agent is one or two of imidazole adducts, tertiary amine adducts, and modified amine curing agents.

[0045] The method for preparing the adhesive includes the following steps:

[0046] (a) Add flexible resin, high temperature resistant resin, epoxy resin, pigment and additives to the mixing tank in the order of the mass parts of each component, and stir for 30 to 60 minutes.

[0047] (b) Add the filler and rheology modifier in the order of mass parts, and stir for 2 hours;

[0048] (c) Then cool to below 40°C;

[0049] (d) Add the curing agent according to the mass fraction and stir for 10 minutes (temperature controlled below 40℃).

[0050] (e) Disperse 5 times with a three-roll mill (temperature controlled below 40°C);

[0051] (f) Stir for 10 minutes (keeping the temperature below 40°C);

[0052] (g) Vacuum degassing for 60 minutes;

[0053] (h) The single-component epoxy adhesive is obtained.

[0054] The single-component epoxy adhesive is cured at 115°C for 20 minutes, 120°C for 20 minutes, or 90°C for 60 minutes to obtain the cured single-component epoxy adhesive.

[0055] The overall properties of the cured product are shown in the table below:

[0056] Test Project Test conditions index Reference Standard hardness Shore D 25℃ 90 Shore D Water absorption rate 100℃ boiling water for 1 hour % ≤0.35 Insulation strength KV / mm 25℃ ≥20 Volume resistivity Ω.cm 25℃ <![CDATA[≥1.0×10 15 ]]> Halogen-free Total chlorine ≤ 900 ppm, total bromine ≤ 900 ppm, total chlorine + bromine ≤ 1500 ppm High temperature resistance Reflow soldering at 240-260℃ for 10 minutes No cracking

[0057] Example 1

[0058] The adhesive is composed of the following components: 5 parts by weight of flexible resin; 1 part by weight of high-temperature resistant resin; 50 parts by weight of epoxy resin; 2.5 parts by weight of pigment; 1.5 parts by weight of additive; 50 parts by weight of filler; 1.5 parts by weight of rheology modifier; and 10 parts by weight of curing agent.

[0059] in,

[0060] The flexible resin is one or more of the following: core-shell modified epoxy resin, rubber modified epoxy resin, and sulfur rubber modified epoxy resin.

[0061] The high-temperature resistant resin is one or more of the following: phenolic modified epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, multifunctional epoxy resin, and naphthalene ring epoxy resin.

[0062] The epoxy resin is one or both of bisphenol A epoxy resin and bisphenol F epoxy resin;

[0063] The pigment is one or more of the following: red, yellow, blue, white, and black;

[0064] The additive is one or both of the following: organosilicon defoamer and silane coupling agent;

[0065] The filler is one or both of alumina and silica powder;

[0066] The rheology modifier is one or two of thixotropic rheology modifiers and fumed silica.

[0067] The curing agent is one or two of imidazole adducts, tertiary amine adducts, and modified amine curing agents;

[0068] The preparation method includes the following steps:

[0069] (a) Add flexible resin, high temperature resistant resin, epoxy resin, pigment and additives to the mixing tank in the order of the mass parts of each component, and stir for 30 to 60 minutes.

[0070] (b) Add the filler and rheology modifier in the order of mass parts, and stir for 2 hours;

[0071] (c) Then cool to below 40°C;

[0072] (d) Add the curing agent according to the mass fraction and stir for 10 minutes (temperature controlled below 40℃).

[0073] (e) Disperse 5 times with a three-roll mill (temperature controlled below 40°C);

[0074] (f) Stir for 10 minutes (keeping the temperature below 40°C);

[0075] (g) Vacuum degassing for 60 minutes;

[0076] (h) The single-component epoxy adhesive is obtained.

[0077] The single-component epoxy adhesive is cured at 115°C for 20 minutes, 120°C for 20 minutes, or 90°C for 60 minutes to obtain the cured single-component epoxy adhesive.

[0078] The properties of the cured product are shown in the table below:

[0079] Test Project Test conditions index Reference Standard hardness Shore D 25℃ 91 Shore D Water absorption rate 100℃ boiling water for 1 hour % 0.15 Insulation strength KV / mm 25℃ 22 Volume resistivity Ω.cm 25℃ <![CDATA[3.0×10 15 ]]> Halogen-free Total chlorine ≤ 900 ppm, total bromine ≤ 900 ppm, total chlorine + bromine ≤ 1500 ppm High temperature resistance Reflow soldering at 240-260℃ for 10 minutes No cracking

[0080] Example 2

[0081] The adhesive is composed of the following components: 25 parts by weight of flexible resin; 5 parts by weight of high-temperature resistant resin; 30 parts by weight of epoxy resin; 2.5 parts by weight of pigment; 1.5 parts by weight of additive; 50 parts by weight of filler; 1.5 parts by weight of rheology modifier; and 5 parts by weight of curing agent.

[0082] in,

[0083] The flexible resin is one or more of the following: core-shell modified epoxy resin, rubber modified epoxy resin, and sulfur rubber modified epoxy resin.

[0084] The high-temperature resistant resin is one or more of the following: phenolic modified epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, multifunctional epoxy resin, and naphthalene ring epoxy resin.

[0085] The epoxy resin is one or both of bisphenol A epoxy resin and bisphenol F epoxy resin;

[0086] The pigment is one or more of the following: red, yellow, blue, white, and black;

[0087] The additive is one or both of the following: organosilicon defoamer and silane coupling agent;

[0088] The filler is one or both of alumina and silica powder;

[0089] The rheology modifier is one or two of thixotropic rheology modifiers and fumed silica.

[0090] The curing agent is one or two of imidazole adducts, tertiary amine adducts, and modified amine curing agents;

[0091] The preparation method includes the following steps:

[0092] (a) Add flexible resin, high temperature resistant resin, epoxy resin, pigment and additives to the mixing tank in the order of the mass parts of each component, and stir for 30 to 60 minutes.

[0093] (b) Add the filler and rheology modifier in the order of mass parts, and stir for 2 hours;

[0094] (c) Then cool to below 40°C;

[0095] (d) Add the curing agent according to the mass fraction and stir for 10 minutes (temperature controlled below 40℃).

[0096] (e) Disperse 5 times with a three-roll mill (temperature controlled below 40°C);

[0097] (f) Stir for 10 minutes (keeping the temperature below 40°C);

[0098] (g) Vacuum degassing for 60 minutes;

[0099] (h) The single-component epoxy adhesive is obtained.

[0100] The single-component epoxy adhesive is cured at 115°C for 20 minutes, 120°C for 20 minutes, or 90°C for 60 minutes to obtain the cured single-component epoxy adhesive.

[0101] The properties of the cured product are shown in the table below:

[0102] Test Project Test conditions index Reference Standard hardness Shore D 25℃ 90 Shore D Water absorption rate 100℃ boiling water for 1 hour % 0.17 Insulation strength KV / mm 25℃ ≥23.1 Volume resistivity Ω.cm 25℃ <![CDATA[3.6×10 15 ]]> Halogen-free Total chlorine ≤ 900 ppm, total bromine ≤ 900 ppm, total chlorine + bromine ≤ 1500 ppm High temperature resistance Reflow soldering at 240-260℃ for 10 minutes No cracking

[0103] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A one-component epoxy adhesive for thermal components, characterized in that: It comprises the following components: 5-25 parts by weight of flexible resin; 1-5 parts by weight of high-temperature resistant resin; 30-50 parts by weight of epoxy resin; 0-5 parts by weight of pigment; 0-3 parts by weight of additives; 30-50 parts by weight of filler; 0-3 parts by weight of rheology modifier; and 5-15 parts by weight of curing agent.

2. The single-component epoxy adhesive for thermal components according to claim 1, characterized in that: The flexible resin is one or more of the following: core-shell modified epoxy resin, rubber modified epoxy resin, and sulfur rubber modified epoxy resin. The high-temperature resistant resin is one or more of the following: phenolic modified epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, multifunctional epoxy resin, and naphthalene ring epoxy resin. The epoxy resin is one or both of bisphenol A epoxy resin and bisphenol F epoxy resin; The pigment is one or more of the following: red, yellow, blue, white, and black; The additive is one or both of organosilicon defoamers and silane coupling agents; The filler is one or two of alumina and silica powder; The rheology modifier is one or two of thixotropic rheology modifiers and fumed silica; The curing agent is one or two of imidazole adducts, tertiary amine adducts, and modified amine curing agents.

3. A one-component epoxy adhesive for thermal components according to claim 1 or 2, characterized in that: The thermal component is a PTC, PPTC, or NTC.

4. A method for preparing a one-component epoxy adhesive for thermal components as described in any one of claims 1 to 3, characterized in that: Includes the following steps, (a) Add flexible resin, high temperature resistant resin, epoxy resin, pigment and additives to the mixing tank in the order of the mass parts of each component, and stir for 30 to 60 minutes. (b) Add the filler and rheology modifier in the order of mass parts, and stir for 2 hours; (c) Then cool to below 40°C; (d) Add the curing agent according to the mass fraction, stir for 10 minutes, and keep the temperature below 40℃; (e) Disperse the product five times using a three-roll mill, keeping the temperature below 40°C; (f) Stir for 10 minutes, keeping the temperature below 40°C; (g) Vacuum degassing for 60 minutes; (h) The single-component epoxy adhesive is obtained.

5. A method of using a one-component epoxy adhesive for thermal components as described in any one of claims 1 to 3, characterized in that: The one-component epoxy adhesive is coated or screen-printed onto the heat-sensitive component and cured at 90°C to 120°C for 20-60 minutes to form a cured one-component epoxy adhesive.