Self-crosslinking flame-retardant insulating material and method of preparation

Abstract

The present application relates to self-crosslinking flame-retardant insulating material and preparation method, belong to insulating material preparation technical field.The self-crosslinking flame-retardant insulating material includes the following raw materials: polyethylene, modified vinyl silane, epoxy flame retardant, water production agent, catalyst, initiator;Modified vinyl silane is made by ring-opening reaction product and diamine compound through condensation reaction;Ring-opening reaction product is made by epoxy silane coupling agent and 2,2-dihydroxy methyl propionic acid derivative reaction;2,2-dihydroxy methyl propionic acid derivative is made by 2,2-dihydroxy methyl propionic acid and acrylic acid through esterification reaction;Epoxy flame retardant is made by terminal hydroxyl dendrimer and epoxidation agent through epoxidation reaction;Terminal hydroxyl dendrimer is made by hexachloro cyclotriphosphazene and alkyl binary primary alcohol through substitution reaction.The present application introduces modified vinyl silane and epoxy flame retardant, forms double crosslinking interpenetrating network in the obtained material, and further solves the problems in the background art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of insulating material preparation, and particularly relates to a self-crosslinking flame-retardant insulating material and a preparation method. BACKGROUND

[0002] Insulating materials are often used in the field of cable sheath materials, and are used to achieve the purpose of protecting cables and ensuring the safety of cable applications due to their excellent insulating properties. Common insulating materials are usually made by melting and mixing high molecular materials, fillers and additives, and then forming. Among them, the common high molecular materials include traditional natural rubber, polyvinyl chloride, polyolefin, etc. The aforementioned various high molecular materials have their own advantages and disadvantages. Therefore, the development trend of existing insulating materials is to mix different types of high molecular materials to form a blended material, so as to play to the strengths of each material and overcome the weaknesses of each material, and obtain a sheath material with excellent comprehensive performance. Among them, the self-crosslinking insulating material is a multi-component high molecular material that forms a crosslinked interpenetrating network in the mixed system. This self-crosslinking insulating material greatly improves the insulating property and mechanical property of the obtained material due to the formation of an interpenetrating network system in the material system. The most commonly used self-crosslinking insulating material is a silane crosslinking polyethylene material, which is made by melting and mixing polyethylene and olefin silane. The silane crosslinking polyethylene material overcomes the low temperature resistance of polyethylene and takes advantage of the excellent elastic properties of polyethylene due to the introduction of silane (a high-temperature-resistant high molecular material) and the formation of a crosslinked interpenetrating network (material structure enhancement) in the formed material.

[0003] In order to obtain a high-flame-retardant silane crosslinking polyethylene material, it is necessary to introduce a flame-retardant filler into the mixed system of polyethylene and olefin silane. Whether the introduced flame-retardant filler is an inorganic flame-retardant filler or an organic flame-retardant filler, the mechanical property of the obtained material will be reduced due to the space effect and steric hindrance effect of the filler itself which does not participate in crosslinking. SUMMARY

[0004] The purpose of the present application is to provide a self-crosslinking flame-retardant insulating material and a preparation method, which can solve the problem of reduced mechanical property caused by the introduction of a flame-retardant filler in the crosslinked material, and obtain a self-crosslinking insulating material with excellent mechanical property and flame-retardant property.

[0005] One purpose of the present application can be achieved by the following technical solutions:

[0006] The self-crosslinking flame-retardant insulating material comprises the following raw materials by weight: 100 parts of polyethylene, 5-12 parts of modified vinyl silane, 20-35 parts of epoxy flame retardant, 0.05-0.4 parts of water-producing agent, 0.1-1 parts of catalyst, and 0.1-0.5 parts of initiator.

[0007] The modified vinyl silane is made by condensation reaction of a ring-opening reaction product and a diamine compound; the ring-opening reaction product is made by reaction of an epoxy silane coupling agent and a 2,2-dimethylol propionic acid derivative; the 2,2-dimethylol propionic acid derivative is made by esterification reaction of 2,2-dimethylol propionic acid and acrylic acid;

[0008] The epoxy flame retardant is made by epoxidation reaction of a hydroxyl-terminated dendrimer and an epoxidation agent; the hydroxyl-terminated dendrimer is made by substitution reaction of hexachlorotriphosphazene and an alkyl primary diol.

[0009] Further, the condensation reaction condition is: reaction in a first organic solvent and a condensation agent, reaction temperature is 70-95℃, and reaction time is 4-8h.

[0010] Further, the ring-opening reaction condition is: reaction in a second organic solvent, reaction pH is 9-10, reaction temperature is 50-70℃, and reaction time is 2-4h.

[0011] Further, the esterification reaction condition is: reaction in a third organic solvent and an esterification reaction catalyst, reaction temperature is 70-95℃, and reaction time is 3-8h.

[0012] Further, the molar ratio of the epoxy silane coupling agent, the 2,2-dimethylol propionic acid derivative, and the diamine compound is 1:1-1.3:1-1.3; the molar ratio of the 2,2-dimethylol propionic acid and the acrylic acid is 1:1-1.2.

[0013] Further, the first organic solvent is one of tetrahydrofuran, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, and dichloromethane.

[0014] Further, the diamine compound is one of 1,4-butanediamine and 1,6-hexanediamine.

[0015] Further, the condensation agent is a mixture of dicyclohexyl carbodiimide (DCC) and 4-N,N-dimethylpyridine (DMAP).

[0016] Further, the second organic solvent is one of tetrahydrofuran, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, and dichloromethane.

[0017] Preferably, when the first organic solvent and the second organic solvent are the same, after the ring-opening reaction, no impurity removal step of the ring-opening reaction product is needed, and the condensation reaction is directly performed.

[0018] Further, the third organic solvent is one of tetrahydrofuran, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane.

[0019] Further, the esterification reaction catalyst is one of concentrated sulfuric acid with a mass fraction of 98%, p-toluenesulfonic acid.

[0020] In the preparation process of the modified vinyl silane, a double bond and a carboxyl group are introduced into the silane coupling agent through ring-opening grafting (ring-opening reaction of epoxy and hydroxyl groups) of the epoxy silane coupling agent and the 2,2-dimethylol propionic acid derivative, and then an amino group is introduced into the silane coupling agent through condensation reaction of the carboxyl group and the amino group in the diamine compound, so as to obtain the modified vinyl silane containing both the double bond and the amino group.

[0021] The 2,2-dimethylol propionic acid derivative contains a double bond through esterification reaction of the hydroxyl group in the 2,2-dimethylol propionic acid and the carboxyl group in the acrylic acid.

[0022] Further, the molecular structure of the 2,2-dimethylol propionic acid derivative is as follows.

[0023]

[0024] Further, the conditions of the epoxidation reaction are as follows: the reaction pH is 10.5-11, the reaction temperature is 50-70°C, and the reaction time is 6-10 h in the fourth organic solvent.

[0025] Further, the fourth solvent is one of ethanol, tetrahydrofuran, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, benzene, toluene.

[0026] Further, the substitution reaction conditions are as follows: the reaction is carried out under the protection of nitrogen in the fifth organic solvent and an acid-adsorbing agent, the reaction temperature is 0-10°C, and the reaction time is 1-6 h.

[0027] Further, the fifth organic solvent is one of acetone, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, benzene, toluene.

[0028] Further, the acid-adsorbing agent is one of potassium carbonate and sodium carbonate.

[0029] Further, the molar ratio of the hexachlorotriphosphazene and the alkyl primary diol is 1:6-10.

[0030] Further, the number of carbon atoms in the alkyl group in the alkyl primary diol is greater than or equal to 4, such as 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, etc.

[0031] Preferably, the alkyl di-primary alcohol is 1,12-dodecanediol.

[0032] Further, the molecular structure of the hexachlorotriphosphazene is shown as follows.

[0033]

[0034] Further, the molar ratio of the alkyl di-primary alcohol and the epoxidizing agent is 1:2-3.

[0035] Further, the epoxidizing agent is epichlorohydrin.

[0036] In the present application, the hexachlorotriphosphazene is used as a rigid flame-retardant core of a hydroxyl-terminated dendrimer compound, and then an etherification reaction of chloro groups and alcohol hydroxyl groups is carried out to obtain a hydroxyl-terminated dendrimer compound, wherein, by screening alcohol hydroxyl compounds, an alkyl di-primary alcohol is used as a source of alcohol hydroxyl groups to introduce a flexible alkyl chain outside the rigid flame-retardant core, so that the obtained hydroxyl-terminated dendrimer compound has a rigid flame-retardant core and a flexible outer chain, and finally the hydroxyl groups at the end of the flexible outer chain are epoxidized to form an epoxy flame retardant.

[0037] Further, the self-crosslinking flame-retardant insulating material further comprises 1-10 parts by weight of an auxiliary agent, which is one or a mixture of several of the commonly known antioxidants and lubricants in the technical field.

[0038] Further, the water-producing agent is zinc acetate.

[0039] Further, the catalyst is one of the organic tin catalysts.

[0040] Further, the initiator is one of the peroxides.

[0041] The second object of the present application is to provide a preparation method of a self-crosslinking flame-retardant insulating material, comprising:

[0042] After mixing the polyethylene, the modified vinyl silane and the initiator, melt blending is carried out through a double-screw extruder, and granulation is carried out to obtain a first material, wherein the extrusion temperature is 170-190°C.

[0043] After mixing the first material, the epoxy flame retardant, the water-producing agent and the catalyst, melt blending is carried out through a double-screw extruder, and extrusion and molding are carried out to obtain a self-crosslinking flame-retardant insulating material, wherein the extrusion temperature is 180-200°C.

[0044] The present application has the following beneficial effects:

[0045] In the present application, the amino group, double bond and dendritic epoxy flame retardant in the modified vinyl silane are used to form a double crosslinking interpenetrating network in the obtained self-crosslinking flame-retardant insulating material, wherein one crosslinking interpenetrating network is a double bond crosslinking interpenetrating network formed by one-step grafting and two-step catalytic crosslinking of the double bond in the modified vinyl silane and polyethylene, and the other crosslinking interpenetrating network is an interpenetrating crosslinking network formed by ring-opening crosslinking between the amino group (derived from the modified vinyl silane) in the former crosslinking network and the end epoxy group of the flexible long chain in the dendritic epoxy flame retardant. While introducing the flame retardant, the crosslinking degree of the obtained material is not reduced, but is improved, and a self-crosslinking network with a rigid flame-retardant core and a flexible long chain is formed on the basis of the original self-crosslinking network. Not only is the mechanical property of the material further improved, and the technical problems mentioned in the background art are solved, but also the combination of the rigid flame-retardant core and the flexible long chain can coordinate to play an excellent toughening effect, so that the obtained material has good toughness. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0047] Embodiment 1

[0048] Preparation of modified vinyl silane:

[0049] A1, 0.1 mol 2,2-dimethylol propionic acid, 0.1 mol acrylic acid and 100 mL toluene were uniformly mixed, then 0.5 g p-toluenesulfonic acid was added under stirring, heated to 70℃, and the reaction was kept stirring for 8 h. Subsequently, the reaction solution was concentrated by rotary evaporation, water was added, and the mixture was extracted with ethyl acetate, washed and dried to obtain a 2,2-dimethylol propionic acid derivative;

[0050] A2, 0.1 mol epoxy silane coupling agent (KH560), 0.1 mol 2,2-dimethylol propionic acid derivative obtained in step A1 and 120 mL DMF were uniformly mixed, heated to 50℃, and the pH of the reaction solution was adjusted to 9-10. The reaction was kept stirring for 4 h, then 50 mL containing 0.16 mol DCC and 0.03 mol DMAP was added under stirring, and the mixture was stirred for 1.5 h. Subsequently, 40 mL containing 0.1 mol 1,4-butanediamine in DMF was added, and the reaction was kept stirring for 6 h. Subsequently, the reaction solution was concentrated, water was added, and the mixture was extracted with ethyl acetate, washed and dried to obtain a modified vinyl silane.

[0051] Embodiment 2

[0052] Preparation of modified vinyl silane:

[0053] A1, 0.1 mol 2,2-dimethylol propionic acid, 0.12 mol acrylic acid and 100 mL toluene were mixed uniformly, 0.5 g p-toluenesulfonic acid was added under stirring, heated to 95℃, and the reaction was carried out under stirring for 3 h, then the solvent was removed by rotary evaporation, washed and dried to obtain 2,2-dimethylol propionic acid derivative;

[0054] A2, 0.1 mol epoxy silane coupling agent (KH560), 0.13 mol 2,2-dimethylol propionic acid derivative obtained in step A1 and 120 mL DMF were mixed uniformly, heated to 70℃, and the pH of the reaction solution was adjusted to 9-10 with sodium hydroxide, and the reaction was carried out under stirring for 2 h, then 50 mL containing 0.16 mol DCC and 0.03 mol DMAP was added under stirring, and the reaction was carried out under stirring for 1 h, then 40 mL containing 0.1-0.15 mol 1,4-butanediamine in DMF was added, and the reaction was carried out under stirring for 3 h, then the reaction solution was concentrated, extracted with ethyl acetate after adding water, washed and dried to obtain modified vinyl silane.

[0055] Example 3

[0056] Preparation of epoxy flame retardant:

[0057] B1, 0.1 mol hexachlorotriphosphazene, 0.7 mol 1,12-dodecanediol, excess potassium carbonate powder (0.5 mol) and 200 mL acetone were mixed uniformly, and the reaction was carried out under stirring for 6 h under nitrogen protection and at 0-10℃, then the filtrate was obtained by suction filtration, water was added to the filtrate, the formed precipitate was suction filtered, and the filter cake was washed and dried to obtain hydroxyl-terminated dendrimer;

[0058] B2, the hydroxyl-terminated dendrimer obtained in step B1, 1.4 mol epichlorohydrin and 300 mL tetrahydrofuran were mixed uniformly, the pH of the reaction solution was adjusted to 10.5-11 with sodium hydroxide, heated to 50℃, and the reaction was carried out for 10 h, then the solvent was removed by rotary evaporation, washed and dried to obtain epoxy flame retardant.

[0059] Example 4

[0060] Preparation of epoxy flame retardant:

[0061] B1, 0.1 mol hexachlorotriphosphazene, 1 mol 1,12-dodecanediol, excess potassium carbonate powder (0.5 mol) and 200 mL acetone were mixed uniformly, stirred at 10°C for 1 h under nitrogen protection, filtered, water was added to the filtrate, the formed precipitate was filtered, and the filter cake was washed and dried to obtain the hydroxyl-terminated dendrimer;

[0062] B2, the hydroxyl-terminated dendrimer obtained in step B1, 3 mol epichlorohydrin and 300 mL tetrahydrofuran were mixed uniformly, the pH of the reaction solution was adjusted to 10.5-11 with sodium hydroxide, heated to 70°C, and reacted for 5 h, the solvent was removed by rotary evaporation, washed and dried to obtain the epoxy flame retardant.

[0063] Example 5

[0064] Preparation of the self-crosslinking flame-retardant insulation material:

[0065] First step, including the following raw materials by weight: low-density polyethylene 100 parts, modified vinyl silane prepared in Example 1 5 parts, epoxy flame retardant prepared in Example 2 20 parts, water generating agent (zinc acetate) 0.05 parts, catalyst (dibutyltin dilaurate) 0.1 parts, initiator (benzoyl peroxide tert-butyl ester) 0.1 parts;

[0066] Second step, the low-density polyethylene, modified vinyl silane and initiator were mixed and melt blended by a twin-screw extruder, and then granulated to obtain a first material, wherein the extrusion temperature was 170-190°C; the first material, the epoxy flame retardant, the water generating agent and the catalyst were mixed and melt blended by a twin-screw extruder, and then extruded and molded (radiation) to obtain the self-crosslinking flame-retardant insulation material, wherein the extrusion temperature was 180-200°C.

[0067] Example 6

[0068] Preparation of the self-crosslinking flame-retardant insulation material:

[0069] First step, including the following raw materials by weight: low-density polyethylene 100 parts, modified vinyl silane prepared in Example 1 5 parts, epoxy flame retardant prepared in Example 2 20 parts, water generating agent (zinc acetate) 0.05 parts, catalyst (dibutyltin dilaurate) 0.1 parts, initiator (benzoyl peroxide tert-butyl ester) 0.1 parts;

[0070] Second step, the low-density polyethylene, modified vinyl silane and initiator were mixed and melt blended by a twin-screw extruder, and then granulated to obtain a first material, wherein the extrusion temperature was 170-190°C; the first material, the epoxy flame retardant, the water generating agent and the catalyst were mixed and melt blended by a twin-screw extruder, and then extruded and molded (radiation) to obtain the self-crosslinking flame-retardant insulation material, wherein the extrusion temperature was 180-200°C.

[0071] Example 7

[0072] Preparation of self-crosslinking flame-retardant insulation material:

[0073] The first step includes the following raw materials by weight: 100 parts of low-density polyethylene, 12 parts of modified vinyl silane prepared in Example 1, 35 parts of epoxy flame retardant prepared in Example 2, 0.4 parts of water production agent (zinc acetate), 1 part of catalyst (dibutyltin dilaurate), and 0.5 parts of initiator (benzoyl peroxide tert-butyl ester);

[0074] The second step is to melt blend the low-density polyethylene, modified vinyl silane, and initiator after mixing, granulate to obtain a first material, wherein the extrusion temperature is 170-190°C; and melt blend the first material, epoxy flame retardant, water production agent, and catalyst after mixing, extrude and shape (radiate) to obtain a self-crosslinking flame-retardant insulation material, wherein the extrusion temperature is 180-200°C.

[0075] Example 8

[0076] Preparation of self-crosslinking flame-retardant insulation material:

[0077] The first step includes the following raw materials by weight: 100 parts of low-density polyethylene, 5 parts of modified vinyl silane prepared in Example 1, 20 parts of epoxy flame retardant prepared in Example 2, 0.05 parts of water production agent (zinc acetate), 0.1 parts of catalyst (dibutyltin dilaurate), 0.1 parts of initiator (benzoyl peroxide tert-butyl ester), 0.5 parts of lubricant (polyethylene wax), and 1.2 parts of antioxidant 1010;

[0078] The second step is to melt blend the low-density polyethylene, modified vinyl silane, and initiator after mixing, granulate to obtain a first material, wherein the extrusion temperature is 170-190°C; and melt blend the first material, epoxy flame retardant, water production agent, lubricant, antioxidant 1010, and catalyst after mixing, extrude and shape (radiate) to obtain a self-crosslinking flame-retardant insulation material, wherein the extrusion temperature is 180-200°C.

[0079] Comparative Example 1

[0080] Preparation of self-crosslinking insulation material:

[0081] Compared with Example 5, the epoxy flame retardant in the raw materials is replaced with an equal amount of organic phosphorus flame retardant DMMP, and the rest is the same.

[0082] Comparative Example 2

[0083] Preparation of self-crosslinking insulation material:

[0084] Comparative Example 3

[0085] Comparative Example 3

[0086] Preparation of self-crosslinking insulation material:

[0087] Comparative Example 3

[0088] The insulation materials obtained in Examples 5-8 and Comparative Examples 1-3 were subjected to physical property tests, and the test results are shown in Table 1.

[0089] Table 1

[0090] tensile strength tensile elongation at break notched impact strength flame retardant rating GB / T 1040.2 GB / T 1040.2 GB / T 1043.1 UL-94 unit Mpa ％ KJ / m 2 ]] \ Example 5 26.6 259 10.0 V-0 Example 6 27.1 276 10.5 V-0 Example 7 28.2 285 11.1 V-0 Example 8 26.9 263 10.3 V-0 Comparative Example 1 19.2 202 4.2 V-0 Comparative Example 2 23.7 232 7.4 V-0 Comparative Example 3 23.3 238 6.7 V-2

[0091] As can be seen from the data in Table 1, the insulation materials obtained in Examples 5-8 have good flame retardant properties, tensile strength and notched impact strength.

[0092] In the description of the specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0093] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A self-crosslinking flame-retardant insulating material, characterized in that, The composition comprises the following raw materials by weight: 100 parts of polyethylene, 5-12 parts of modified vinyl silane, 20-35 parts of epoxy flame retardant, 0.05-0.4 parts of water production agent, 0.1-1 parts of catalyst, and 0.1-0.5 parts of initiator. The modified vinyl silane is prepared by condensation reaction of a ring-opening reaction product and a diamine compound; the ring-opening reaction product is prepared by reaction of an epoxy silane coupling agent and a 2,2-dimethylol propionic acid derivative; and the 2,2-dimethylol propionic acid derivative is prepared by esterification reaction of 2,2-dimethylol propionic acid and acrylic acid. The epoxy flame retardant is prepared by epoxidation reaction of a hydroxyl-terminated dendrimer and an epoxidizing agent; and the hydroxyl-terminated dendrimer is prepared by substitution reaction of hexachlorotriphosphazene and an alkyl primary alcohol.

2. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The condensation reaction is carried out in a first organic solvent and a condensing agent, at a temperature of 70-95℃ for 4-8 hours.

3. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The ring-opening reaction is carried out in a second organic solvent, at a pH of 9-10, a temperature of 50-70℃ for 2-4 hours.

4. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The esterification reaction is carried out in a third organic solvent and an esterification catalyst, at a temperature of 70-95℃ for 3-8 hours.

5. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The molar ratio of the epoxy silane coupling agent, the 2,2-dimethylol propionic acid derivative, and the diamine compound is 1:1-1.3:1-1.3; and the molar ratio of the 2,2-dimethylol propionic acid and the acrylic acid is 1:1-1.

2.

6. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The diamine compound is one of 1,4-butanediamine and 1,6-hexanediamine.

7. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The epoxidation reaction is carried out in a fourth organic solvent, at a pH of 10.5-11, a temperature of 50-70℃ for 6-10 hours.

8. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The substitution reaction is carried out in a fifth organic solvent, an acid-adsorbing agent, and nitrogen protection, at a temperature of 0-10℃ for 1-6 hours.

9. A self-crosslinking flame-retardant insulating material according to claim 1, characterized in that, The molar ratio of the hexachlorotriphosphazene and the alkyl primary alcohol is 1:6-10; the alkyl primary alcohol has a carbon atom number greater than or equal to 4; and the molar ratio of the alkyl primary alcohol and the epoxidizing agent is 1:2-3, and the epoxidizing agent is epichlorohydrin.

10. The method of claim 1, wherein the self-crosslinking flame-retardant insulation material is prepared by mixing the flame retardant, the crosslinking agent, the crosslinking catalyst, the antioxidant, the filler, and the solvent. The composition comprises: The polyethylene, the modified vinyl silane, and the initiator are mixed, melt-blended by a double-screw extruder, and granulated to obtain a first material; The first material, the epoxy flame retardant, the water production agent, and the catalyst are mixed, melt-blended by a double-screw extruder, extruded, and molded to obtain a self-crosslinking flame-retardant insulation material.

Images