Polyester resin for polyurethane structural adhesive with high heat conductivity coefficient and low viscosity

Abstract

The invention provides polyester resin for a polyurethane structural adhesive with high heat conductivity coefficient and low viscosity. The polyester resin is prepared by polymerization reaction of ethylene acrylic acid copolymer, polybasic acid and polyhydric alcohol in the presence of a catalyst, wherein the ethylene-acrylic acid copolymer is prepared by carrying out polymerization reaction on ethylene, acrylic ester and silicon-containing acrylic ester in the presence of a catalyst; acrylate is selected from one or more of ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, dodecyl (meth) acrylate and hexadecyl (meth) acrylate; the silicon-containing acrylate is selected from one or more of (methyl) acrylic acid triethoxy silane propyl ester. According to the polyurethane structural adhesive containing the polyester resin, the heat conductivity coefficient can be larger than 5.0 W / (m * K), the viscosity (25 DEG C) is smaller than 25000mpa. S, and the aluminum-to-aluminum bonding shear strength is larger than 32 Mpa. The content of a polyurethane structural adhesive filler containing the polyester resin is not more than 40%.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, in particular to a polyester resin used for a polyurethane structural adhesive with high thermal conductivity and low viscosity. Background Art

[0002] With the rapid development of electric vehicles, more and more electric vehicle industries have high requirements for bonding strength, thermal conductivity, and structural adhesive viscosity for lithium battery structural bonding. Therefore, the electric vehicle industry has a strong demand for the research and development of polyester resins for high thermal conductivity polyurethane structural adhesives for lithium batteries. In order to improve the thermal conductivity, conventional polyurethane structural adhesives have a high content of thermal conductive fillers, resulting in a large density of the adhesive, which is not conducive to the development of lightweight power batteries, and the increase in thermal conductive fillers will inevitably lead to a decrease in resin content, thereby affecting the adhesive's bonding performance to the material. In view of this, the present invention is specially proposed to achieve a polyurethane structural adhesive containing polyester resin that can meet the requirements of thermal conductivity greater than 5.0W / (m*K), viscosity (25°C) less than 25000mpa.s, and the filler content of the polyurethane structural adhesive containing this polyester resin is not more than 40%. Summary of the invention

[0003] In view of the fact that existing plastic film packaging materials cannot fully meet the use requirements in terms of strength and barrier properties, products placed in the packaging for a long time are easily deteriorated and oxidized due to air penetration. The present invention provides a high barrier coating for nylon film and a preparation method thereof.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive, wherein the polyester resin is prepared by polymerization reaction of ethylene acrylic acid copolymer, polyacid and polyol under the action of a catalyst;

[0006] Wherein, the ethylene acrylic acid copolymer is prepared by polymerization reaction of ethylene, acrylic acid ester and silicon-containing acrylic acid ester under the action of a catalyst;

[0007] The acrylate is selected from one or more of ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, dodecyl (meth)acrylate and hexadecyl (meth)acrylate;

[0008] The silicon-containing acrylate is selected from one or more of triethoxysilylpropyl (meth)acrylate.

[0009] Furthermore, the polymerization method of ethylene acrylic acid copolymer is carried out in a stirred autoclave, the stirring time is 12-96 hours, the selected pressure is 5-300 MPa, and the polymerization temperature is 150-300°C.

[0010] Furthermore, the contents of ethylene, acrylate and silicon-containing acrylate are respectively 40%-70% for ethylene, 10%-50% for acrylate and 0.2%-10% for silicon-containing acrylate.

[0011] Furthermore, the molecular weight of the ethylene acrylic acid copolymer is 1000-5000 g / mol.

[0012] Furthermore, the polyol is one or a combination of neopentyl glycol, methyl propylene glycol, and 3-methyl-1,5-pentanediol.

[0013] Furthermore, the polyacid is selected from one or a combination of terephthalic acid, isophthalic acid, phthalic anhydride, adipic acid, and 1,4-cyclohexanedicarboxylic acid.

[0014] Furthermore, the contents of ethylene acrylic acid copolymer, polyacid and polyol are respectively 2%-20% of ethylene acrylic acid copolymer, 25%-80% of polyacid and 15%-85% of polyacid, and the catalyst accounts for 0.0005-0.2% of the total mass of the raw materials of the modified polyester resin.

[0015] Furthermore, the catalyst is one or a combination of titanium catalysts and tin catalysts.

[0016] Furthermore, the preparation method of the modified polyester resin is: stirring and dehydrating the polyacid, polyol and catalyst at 130°C to 200°C for 1 to 4 hours, then heating to 210°C to 270°C, evacuating until the vacuum degree is below -0.099Mpa, then setting the temperature to 210°C to 280°C for ester exchange reaction until the hydroxyl value is 170 to 250mgKOH / g, terminating the reaction, reducing the pressure and temperature to discharge the material.

[0017] Furthermore, the mass ratio of isocyanate to polyester resin in the polyurethane structural adhesive containing polyester resin is 1:20-400.

[0018] Compared with the prior art, the invention has the following beneficial effects: the polyurethane structural adhesive containing polyester resin can meet the requirements of thermal conductivity greater than 5.0W / (m*K), viscosity (25°C) less than 25000mpa.s, and aluminum-to-aluminum bonding shear strength greater than 32Mpa. The filler content of the polyurethane structural adhesive containing the polyester resin is not more than 40%. The polyurethane structural adhesive containing the polyester resin can meet the requirements of thermal conductivity bonding of lithium battery packs, and the low viscosity of the structural adhesive is convenient for production and coating. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] Example 1

[0021] This embodiment provides a polyester resin, which is prepared by the following method:

[0022] Into a stirred high-pressure reactor, 40 g of ethylene, 30 g of butyl methacrylate, 28 g of dodecyl methacrylate, 2 g of triethoxysilylpropyl acrylate and 0.003 g of a homemade catalyst were introduced in sequence, stirring was turned on, the temperature was set to 180° C. and the pressure was 180 MPa for 3 hours, the temperature was raised to 240° C. and the pressure was 210 MPa for 24 hours, then normal pressure was restored, small molecular monomers were removed through a distillation tower, the temperature was lowered to 130° C., the material was discharged and stored, and an ethylene acrylic acid copolymer A with a molecular weight of 1750 g / mol was obtained.

[0023] Add 10g of ethylene acrylic acid copolymer A, 15g of isophthalic acid, 25g of adipic acid, 35g of methyl propanediol, 15g of 3-methyl-1,5-pentanediol and 0.007g of titanium catalyst to the reactor in sequence, turn on stirring, start heating to 155°C and keep the temperature constant for 3h, stabilize the dehydration rate (through the distillation tower, the top temperature is maintained at 120°C), continue to heat to 190°C and turn on the vacuum pump, control the vacuum degree to slowly increase to -0.1MPa. Heat to 245°C for ester exchange reaction, and introduce nitrogen to take away excess polyols and small molecule alcohols. After 8h from the start of vacuuming, take samples every 2h for central control analysis until the final acid value is about (1.0-3.0) mgKOH / g and the hydroxyl value is 195mgKOH / g, restore normal pressure, reduce to 140°C, discharge and store, and obtain polyester resin D.

[0024] Example 2

[0025] This embodiment provides a polyester resin, which is prepared by the following method:

[0026] Into a stirred high-pressure reactor, 25 g of ethylene, 20 g of dodecyl methacrylate, 51.5 g of hexadecyl methacrylate, 3.5 g of triethoxysilylpropyl methacrylate and 0.005 g of a homemade catalyst were introduced in sequence, stirring was turned on, the temperature was set to 170° C. and the pressure was 180 MPa for 3 h, the temperature was raised to 220° C. and the pressure was 210 MPa for 18 h, the temperature was further raised to 250° C. and the pressure was 220 MPa for 12 h, then normal pressure was restored, small molecular monomers were removed through a distillation tower, the temperature was lowered to 140° C., the material was discharged and stored, and an ethylene acrylic acid copolymer B with a molecular weight of 2200 g / mol was obtained.

[0027] 12g of ethylene acrylic acid copolymer B, 10g of isophthalic acid, 12g of phthalic anhydride, 8g of adipic acid, 20g of methyl propylene glycol, 36g of neopentyl glycol and 0.004g of titanium catalyst were added to the reactor in sequence, stirring was turned on, and the temperature was kept constant for 5h when the temperature was raised to 160°C, the dehydration rate was stabilized (through the distillation tower, the tower top temperature was kept at 110°C), and the temperature was continued to rise to 185°C, and the vacuum pump was turned on, and the vacuum degree was controlled to be gradually increased to -0.1MPa. The temperature was raised to 220°C for ester exchange reaction, and nitrogen was introduced to take away the excess polyols and small molecule alcohols. After 6h from the start of vacuuming, the sample was taken every 2h for central control analysis until the final acid value was about (1.0-3.0) mgKOH / g and the hydroxyl value was 220mgKOH / g, and the normal pressure was restored, and the temperature was reduced to 140°C, and the material was discharged and stored to obtain polyester resin E.

[0028] Example 3

[0029] This embodiment provides a polyester resin, which is prepared by the following method:

[0030] Into a stirred high-pressure reactor, 60 g of ethylene, 37.5 g of hexadecyl methacrylate, 2.5 g of triethoxysilylpropyl methacrylate and 0.045 g of a homemade catalyst were introduced in sequence, stirring was turned on, the temperature was set to 180° C. and the pressure was 180 MPa for 10 h, the temperature was raised to 220° C. and the pressure was 210 MPa for 10 h, the temperature was further raised to 250° C. and the pressure was 220 MPa for 6 h, then the pressure was restored to normal pressure, small molecular monomers were removed through a distillation tower, the temperature was lowered to 140° C., the material was discharged and stored, and an ethylene acrylic acid copolymer C with a molecular weight of 3300 g / mol was obtained.

[0031] 6g of ethylene acrylic acid copolymer C, 12g of phthalic anhydride, 6g of terephthalic acid, 15g of adipic acid, 15g of methyl propanediol, 15g of neopentyl glycol, 21g of 3-methyl-1,5-pentanediol and 0.004g of titanium catalyst were added to the reactor in sequence, stirring was turned on, and the temperature was kept constant for 4h when it began to rise to 170℃, the dehydration rate was stabilized (through the distillation tower, the tower top temperature was kept at 115℃), and the temperature was continued to rise to 18℃ and the vacuum pump was turned on, and the vacuum degree was controlled to be gradually increased to -0.1MPa. The temperature was raised to 240℃ for ester exchange reaction, and nitrogen was introduced to take away the excess polyols and small molecule alcohols. After 8h from the start of vacuuming, the sample was taken every 2h for central control analysis until the final acid value was about (1.0-3.0) mgKOH / g and the hydroxyl value was 240mgKOH / g, and the normal pressure was restored and dropped to 140℃, and the material was discharged and stored to obtain polyester resin F.

[0032] After mixing polyester resin DF with spherical alumina of different particle sizes, PM-200 (from Wanhua Chemical) was used as a curing agent. ① After comparing with common resins on the market, the relevant data are as follows.

[0033]

[0034] v The amount of curing agent used is 1.05 in the molar ratio of hydroxyl group in polyester resin or aromatic polyol to isocyanate group in PM-200.

[0035] AC-005 ② and AC-006 ② , among which, ② Ito Oil Manufacturing Co., Ltd. contains aromatic polyols.

[0036] BAK-5 ③， and BAK-40 ③ , among which, ③ Baitu Co., Ltd. spherical alumina.

[0037] It should be noted that the above description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. In addition, the above are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

Claims

1. A polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive, characterized in that: The polyester resin is prepared by polymerization reaction of ethylene acrylic acid copolymer, polyacid and polyol under the action of a catalyst; Wherein, the ethylene acrylic acid copolymer is prepared by polymerization reaction of ethylene, acrylic acid ester and silicon-containing acrylic acid ester under the action of a catalyst; The acrylate is selected from one or more of ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, dodecyl (meth)acrylate and hexadecyl (meth)acrylate; The silicon-containing acrylate is selected from one or more of triethoxysilylpropyl (meth)acrylate.

2. A polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive as claimed in claim 1, characterized in that: The polymerization method of ethylene acrylic acid copolymer is carried out in a stirred autoclave, the stirring time is 12-96 hours, the selected pressure is 5-300 MPa, and the polymerization temperature is 150-300°C.

3. A polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive as claimed in claim 1, characterized in that: The contents of ethylene, acrylate and silicon-containing acrylate are respectively 40%-70% for ethylene, 10%-50% for acrylate and 0.2%-10% for silicon-containing acrylate.

4. A polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive as claimed in claim 1, characterized in that: The molecular weight of the ethylene acrylic acid copolymer is 1000-5000 g / mol.

5. The polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive according to claim 1, characterized in that: The polyol is one or a combination of neopentyl glycol, methyl propylene glycol, and 3-methyl-1,5-pentanediol.

6. A polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive as claimed in claim 1, characterized in that: The polyacid is selected from one or a combination of terephthalic acid, isophthalic acid, phthalic anhydride, adipic acid, and 1,4-cyclohexanedicarboxylic acid.

7. The polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive according to claim 1, characterized in that: The contents of ethylene acrylic acid copolymer, polyacid and polyol are respectively 2%-20% of ethylene acrylic acid copolymer, 25%-80% of polyacid and 15%-85% of polyacid. The catalyst accounts for 0.0005-0.2% of the total mass of the raw materials of the modified polyester resin.

8. The polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive according to claim 1, characterized in that: The catalyst is one or a combination of titanium catalysts and tin catalysts.

9. The polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive according to claim 1, characterized in that: The preparation method of the modified polyester resin is as follows: the polyacid, polyol and catalyst are stirred and dehydrated at 130° C. to 200° C. for 1 to 4 hours, then the temperature is raised to 210° C. to 270° C., and vacuumed until the vacuum degree is below -0.099 MPa, and then the temperature is set to 210° C. to 280° C. for ester exchange reaction until the hydroxyl value is 170 to 250 mgKOH / g, the reaction is terminated, and the pressure and temperature are reduced to discharge the material.

10. The polyester resin for high thermal conductivity and low viscosity polyurethane structural adhesive according to claim 1, characterized in that: The mass ratio of isocyanate to polyester resin in the polyurethane structural adhesive containing polyester resin is 1:20-400.

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