Nanoscale organosilicon cluster hypophosphite flame retardant and preparation method thereof

Abstract

The application discloses a nanoscale organosilicon cluster phosphinic acid flame retardant and a preparation method thereof. The flame retardant is a reticular macromolecular structure flame retardant with group synergistic effect, which is prepared based on hypophosphorous acid, siloxane compound and free radical initiator. The flame retardant realizes the combination of siloxane and hypophosphorous acid in the same structure unit, and improves the flame retardant efficiency. Meanwhile, the structure unit contains hydroxyl functional groups, crosslinking with a matrix such as epoxy resin to improve the crosslinking density. The polymer particle size reaches the nanoscale through a physical method, and the mechanical properties of the material are improved. In addition, the application has high yield, and the preparation process and product post-processing process operation are simple. The flame retardant has the characteristics of high flame retardant efficiency and excellent compatibility, and is a halogen-free high-efficiency phosphorus-silicon synergistic flame retardant.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of nanometer organic silicon system cluster phosphinic acid flame retardant and its preparation method, belong to the technical field of synthesis of material science flame retardant. BACKGROUND

[0002] With the development of social life and the increasing of means of production, the risk source of fire is increasing, and the harm of fire is becoming more and more serious, which seriously threatens public safety and social development. Therefore, the development of high-performance and high-efficiency flame-retardant polymer has become the research focus in the current flame-retardant field.

[0003] In recent years, hypophosphorous acid is widely used in the preparation of gas-phase flame retardant due to its high phosphorus content, but it lacks condensed phase flame retardant effect. Silicon-based flame retardant has excellent condensed phase flame retardant effect, and generates dense residual carbon during heating process, which can isolate heat transfer. The synergistic effect of silicon-based and phosphorus-based flame retardants can efficiently flame-retard the matrix material.

[0004] Due to the introduction of flame retardant, the mechanical properties of the matrix material are affected, thereby limiting the application range of the material. In order to solve this problem, nanoscale flame retardant can be more uniformly dispersed in the matrix, and silicon element can improve the compatibility of flame retardant and matrix material, reducing the loss of mechanical properties. While ensuring the improvement of flame retardant performance, the mechanical strength is maximized. SUMMARY

[0005] The present application provides a new type of nanoscale organic silicon system cluster phosphinic acid flame retardant with little effect on mechanical properties and phosphorus-silicon synergistic effect, and its preparation method. The preparation process of the flame retardant system is simple, fast and high-yield, which can combine hypophosphorous acid and siloxane in the same molecular unit to prepare a flame retardant with synergistic effect of gas phase and condensed phase.

[0006] To solve this problem, the technical scheme adopted by the present application is:

[0007] A preparation method of nanoscale organic silicon system cluster phosphinic acid flame retardant, comprising:

[0008] Hypophosphorous acid and mono- and / or polysiloxane compound are reacted in the presence of a free radical initiator in a solvent system to obtain an organic silicon system phosphinic acid polymer. When exothermic or viscosity increase (such as climbing phenomenon) occurs during the reaction, the solvent system needs to be added to the reaction system for cooling or dilution. After reaction, filter and clean, and the obtained preliminary product organic silicon system cluster phosphinic acid polymer is ball milled to obtain nanoscale organic silicon system cluster phosphinic acid flame retardant.

[0009] In the above technical solution, further, the solvent system contains an additive, the additive is one or more of methanol, ethanol, n-propanol, and isopropanol, and the solvent system contains 70 to 100% by weight of the additive and 0 to 30% by weight of water, preferably, the solvent system contains 80 to 100% by weight of the additive and 0 to 20% by weight of water.

[0010] Further, the siloxane compound is a polysiloxane compound, and can be one or more of tetramethyldivinyldisiloxane, 2,2,4,4-tetramethyltetraethenylcyclotetrasiloxane, methyltrivinylsiloxane, and 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane. Further, the siloxane compound is a polysiloxane compound, and can be one or more of tetramethyldivinyldisiloxane, 2,2,4,4-tetramethyltetraethenylcyclotetrasiloxane, methyltrivinylsiloxane, and 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane.

[0011]

[0012] Further, the free radical initiator is one or more of a compound capable of forming a peroxide, a peroxide compound, and an azo compound, and is preferably the azo compound 2,2'-azobisisobutyronitrile.

[0013] Further, the free radical initiator is added to the reaction system at a rate of 0.1% to 10% of its molar amount per hour based on the molar amount of the olefin compound, and the total amount added is 0.5% to 10%.

[0014] Further, the molar ratio of the olefin to the hypophosphorous acid in the siloxane compound is 3:1 to 1:3, preferably 2:1 to 1:2, and more preferably 1:2.5 to 1:2.05. The above ratio can improve the yield, and can maximize the addition reaction of the phosphorus-carbon bond, so that the contents of silicon and phosphorus are maximized, and the synergistic flame retardation can be maximized.

[0015] Further, the reaction is carried out at a temperature of 50 to 90°C under stirring, the stirring speed is 100 to 500 r / min, preferably 200 to 400 r / min, in the initial reaction, the stirring speed is 300 to 800 r / min, preferably 500 to 800 r / min, when the solvent system is added again to reduce the temperature or dilution, when heat release and / or climbing rod phenomenon occurs, 30 to 50 ml of the solvent system can be added to reduce the temperature and / or reduce the viscosity, and the speed can be appropriately increased, when the heat release and / or climbing rod phenomenon disappears and / or weakens, the speed can be reduced.

[0016] Further, the cleaning is performed with water and / or a solvent additive to a pH value of 4 to 7, the ball milling speed is 400 to 800 r / min, and the ball milling time is 8 to 20 h.

[0017] The present application has the following beneficial effects:

[0018] 1. The nanoscale organosilicon cluster hypophosphite flame retardant of the present application has simple and convenient preparation method, short reaction time and high yield of more than 80%.

[0019] 2. The nanoscale organosilicon cluster hypophosphite flame retardant of the present application combines hypophosphorous acid and siloxane compound in the same molecular unit through chemical bond, forms group synergistic effect, improves flame retardant efficiency, and can obtain high flame retardant effect at a lower addition amount.

[0020] 3. The nanoscale organosilicon cluster hypophosphite flame retardant of the present application has high carbon residue rate; for example, the carbon residue rate at 800℃ in the thermal gravimetric test reaches 50%.

[0021] 4. The nanoscale organosilicon cluster hypophosphite flame retardant of the present application has cluster macromolecular structure, and the silicon element is gathered on the surface, which greatly improves the crosslinking density of the matrix.

[0022] 5. The nanoscale organosilicon cluster hypophosphite flame retardant of the present application introduces siloxane group, and the hydroxyl group reacts with the polymer matrix such as epoxy resin to improve the crosslinking density of the matrix, and greatly improves the compatibility with the polymer; for example, after brittle fracture in the application in the epoxy resin, no obvious defects are found.

[0023] 6. The nanoscale organosilicon cluster hypophosphite flame retardant of the present application introduces siloxane group, which maximizes the mechanical properties of the material; for example, under the same addition amount, the limiting oxygen index of the epoxy resin modified by the phosphorus hetero-fused derivative and the epoxy resin modified by the nanoscale organosilicon cluster hypophosphite are both higher than 29%, the impact strength of the epoxy resin modified by the nanoscale organosilicon cluster hypophosphite is twice that of the epoxy resin modified by the phosphorus hetero-fused derivative, and the impact strength of the epoxy resin modified by the nanoscale organosilicon cluster hypophosphite is only 5% less than that of the pure epoxy resin. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the thermal gravimetric spectrum of the nanoscale organosilicon cluster hypophosphite (MVCP) prepared in Example 1 of the present application.

[0025] Figure 2 is the infrared spectrum of the nanoscale organosilicon cluster hypophosphite (MVCP) prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0026] Example 1

[0027] Step 1 : 80.39 g of hypophosphorous acid was added to a flask, 100 g of 2,2,4,4-tetramethyltetra-vinylcyclotetrasiloxane (MVC) was dissolved in ethanol and then added to the flask by constant pressure dropping funnel while stirring. At the same time, 0.95 g of 2'2-azobis isobutyronitrile (AIBN) was added. Then 0.95 g of AIBN was added every hour, and a total of 3.8 g of AIBN was added. The reaction was maintained at 72 °C. When the reaction exotherm or viscosity rise occurred, 30 ml of ethanol was added to cool down or reduce the viscosity. The crude product precipitated out of the flask and was washed with ethanol and deionized water (i.e. water washing) until the filtrate pH was 6, and a silicone-based clustered hypophosphorous acid polymer was obtained. The silicone-based clustered hypophosphorous acid polymer was dried at 120-180 °C to obtain a dry white solid MVCP with a yield of 97.4%. The MVCP was ball-milled at 500 r / min for 4 hours, paused for 30 minutes, repeated four times. The target product, a nano-sized silicone-based clustered hypophosphorous acid flame retardant, was obtained.

[0028] The flame retardant MVCP prepared in this example was applied in a bismaleimide cyanate ester (BCI) reinforced epoxy resin (BCIEP) system. Its blend was made into a sample of 125 mm x 13 mm x 3 mm. When the addition amount was only 2%, the vertical burning test (UL 94) level was V-1.

[0029] Example 2

[0030] The specific implementation steps were the same as those of Example 1, except that the reaction temperature was changed to 70 °C. The target product, a nano-sized silicone-based clustered hypophosphorous acid flame retardant, was obtained with a yield of 91.7%. It was applied in a BCIEP system. When the addition amount was only 2%, the UL 94 level was V-1.

[0031] Example 3

[0032] The specific implementation steps were the same as those of Example 1, except that the initiator was changed to 2'2-azobis isobutylamidine dihydrochloride (AAPH). The target product, a nano-sized silicone-based clustered hypophosphorous acid flame retardant, was obtained. It was applied in a BCIEP system. When the addition amount was only 2%, the UL 94 level was V-1.

[0033] Example 4

[0034] The specific implementation steps were the same as those of Example 1, except that the reaction solvent was changed to deionized water. The target product, a nano-sized silicone-based clustered hypophosphorous acid flame retardant, was obtained. It was applied in a BCIEP system. When the addition amount was only 2%, the UL 94 level was V-1.

[0035] Example 5

[0036] The same procedure as in Example 1 was followed, except that the raw materials were 76.74 g of hypophosphorous acid and 100 g of methyltrivinylsiloxane, and the amount of initiator AIBN was 1.9 g. The application was in the BCIEP system. When the amount of addition was only 2%, the UL 94 level was V-1.

[0037] Example 6

[0038] The same procedure as in Example 1 was followed, except that the raw materials were 141.9 g of hypophosphorous acid and 100 g of tetramethyldivinyl disiloxane, and the amount of initiator AIBN was 1.7 g. The application was in the BCIEP system. The blend was made into a sample of 125 mm x 13 mm x 3 mm. When the amount of addition was only 2%, the UL 94 level was V-1.

[0039] Example 7

[0040] The same procedure as in Example 1 was followed, except that the raw materials were 122.6 g of hypophosphorous acid and 100 g of 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, and the amount of initiator AIBN was 1.5 g. The application was in the BCIEP system. The blend was made into a sample of 125 mm x 13 mm x 3 mm. When the amount of addition was only 2%, the UL 94 level was V-1.

[0041] Comparative Example 1

[0042] The same procedure as in Example 1 was followed, except that no initiator was added.

[0043] It was found that the target product could not be obtained in this comparative example.

[0044] Comparative Example 2

[0045] The same procedure as in Example 1 was followed, except that no water washing was performed.

[0046] It was found that when the application was in the BCIEP, the UL 94 test result was no level in this comparative example.

[0047] Comparative Example 3

[0048] The same procedure as in Example 1 was followed, except that the MVC was added at one time.

[0049] It was found that the yield of this comparative example was less than 50%.

[0050] The above examples are used to explain the present application, but are not intended to limit the present application, and any modifications and changes made to the present application within the spirit and protection scope of the claims are suitable for the protection scope of the present application.

Claims

1. A method for producing a nanoscale organosilicon-based clustered phosphinic acid flame retardant, characterized by, The solvent system comprises one or more of methanol, ethanol, n-propanol, and isopropanol, and contains 70 to 100% by weight of the additive and 0 to 30% by weight of water. The reaction of hypophosphorous acid with mono and / or polysiloxane compounds in the presence of a radical initiator in a solvent system, wherein the siloxane compound is an olefin compound, the siloxane compound is added by constant pressure dropping funnel, when exothermic or viscosity increase occurs during the reaction, the solvent system is added to the reaction system for cooling or dilution, after the reaction, the obtained primary product, organosilicon cluster hypophosphite polymer, is filtered and washed, and the obtained organosilicon cluster hypophosphite polymer is ball milled to obtain a nanoscale organosilicon cluster hypophosphite flame retardant; the solvent system contains an additive, the washing is washing with water and a solvent additive until the pH value is 4-7, the molar ratio of the olefin to hypophosphorous acid in the siloxane compound is 3:1 to 1:3, and the olefin compound is one or more of 、 、 .

2. The production method according to claim 1, wherein The solvent system contains 80 to 100% by weight of the additive and 0 to 20% by weight of water.

3. The production method according to claim 2, wherein The free radical initiator is one or more of peroxide compounds and azo compounds.

4. The production method according to claim 1, wherein The free radical initiator is azo compound 2,2'-azobisisobutyronitrile.

5. The production method according to claim 1, wherein The free radical initiator is added to the reaction system at a rate of 0.1% to 10% of its molar amount per hour, and the total amount added is 0.5% to 10% of the molar amount of the olefin compound.

6. The production method according to claim 1, wherein The molar ratio of the olefin to hypophosphorous acid in the siloxane compound is 2:1 to 1:

2.

7. The production method according to claim 1, wherein The reactions are all carried out at a temperature of 50 to 90℃ and under stirring, with an initial stirring speed of 100 to 500 r / min, and a stirring speed of 300 to 800 r / min when the solvent system is added again for temperature reduction or dilution.

8. The production method according to claim 1, wherein The reactions are all carried out at a temperature of 50 to 90℃ and under stirring, with an initial stirring speed of 200 to 400 r / min, and a stirring speed of 500 to 800 r / min when the solvent system is added again for temperature reduction or dilution.

9. The production method according to claim 1, wherein The ball milling speed is 400 to 800 r / min, and the ball milling time is 8 to 20 h.

10. The production method according to claim 1, wherein The method is prepared by using any one of claims 1 to 10.

11. A nanoscale organosilicon-based clustered phosphinic acid flame retardant characterized in that, The method is prepared by using any one of claims 1 to 10.

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