Surface-modified zinc alkyl phosphinate flame retardants and modified polycarbonates based thereon

文档序号：1810653 发布日期：2021-11-09 浏览：30次中文

阅读说明：本技术 表面改性的烷基次膦酸锌阻燃剂和基于其的改性聚碳酸酯 (Surface-modified zinc alkyl phosphinate flame retardants and modified polycarbonates based thereon ) 是由罗典岳杰何达程柯左翔于 2021-08-30 设计创作，主要内容包括：本发明属于复合材料领域,具体涉及一种表面改性的烷基次膦酸锌阻燃剂和基于其的改性聚碳酸酯。本发明提供的烷基次膦酸锌阻燃剂,利用硅烷偶联剂对C-(1-2)烷基次膦酸锌表面改性,所得改性阻燃剂的稳定性和残碳量均有提高,阻燃性能提升。本发明将上述烷基次膦酸锌阻燃剂添加至聚碳酸酯基体材料中,所得改性聚碳酸酯在高温高剪切力作用下加工稳定性提高,并充分利用硅系阻燃剂与膦系阻燃剂复配效果,提高阻燃效率。(The invention belongs to the field of composite materials, and particularly relates to a surface-modified zinc alkyl phosphinate flame retardant and modified polycarbonate based on the same. The alkyl zinc phosphinate flame retardant provided by the invention utilizes a silane coupling agent to react with C 1‑2 The alkyl zinc phosphinate is subjected to surface modification, so that the stability and the residual carbon content of the obtained modified flame retardant are improved, and the flame retardant property is improved. According to the invention, the alkyl zinc phosphinate flame retardant is added into the polycarbonate matrix material, the processing stability of the obtained modified polycarbonate is improved under the action of high temperature and high shear force, and the flame retardant efficiency is improved by fully utilizing the compounding effect of the silicon flame retardant and the phosphine flame retardant.)

1. The surface-modified zinc alkyl phosphinate flame retardant is characterized in that the zinc alkyl phosphinate flame retardant is obtained by surface modification through a silane coupling agent, and the zinc alkyl phosphinate is C_1-2Zinc alkyl phosphinate.

2. The surface-modified zinc alkyl phosphinate flame retardant of claim 1, characterized in that the surface modification comprises the following steps: mixing the silane coupling agent with the zinc alkyl phosphinate in a solvent, the silane coupling agent hydrolyzing to surface modify the zinc alkyl phosphinate;

preferably, the surface modification comprises the steps of:

dispersing the zinc alkyl phosphinate in an aqueous solvent to obtain a mixed solution I;

dispersing the silane coupling agent in an anhydrous solvent to obtain a mixed solution II;

and mixing the mixed solution II with the mixed solution I, heating to 60-100 ℃, and adjusting the pH value to 9-10 to obtain the composite material.

3. The surface-modified zinc alkyl phosphinate flame retardant of claim 1 or 2, characterized in that the performance of the surface-modified zinc alkyl phosphinate flame retardant satisfies one or a combination of two or more of the following conditions:

Td_5％at 460 ℃ or higher, preferably Td_5％At a temperature above 485 ℃;

Td_10％at 470 ℃ or higher, preferably Td_10％Above 495 ℃.

4. The surface-modified zinc alkyl phosphinate flame retardant of any one of claims 1 to 3, characterized in that the performance of the surface-modified zinc alkyl phosphinate flame retardant satisfies one or a combination of two or more of the following conditions:

preference is given to

Preference is given to

5. The surface-modified zinc alkyl phosphinate flame retardant of any one of claims 1 to 4, characterized in that the performance of the surface-modified zinc alkyl phosphinate flame retardant satisfies the following condition:

the residual carbon content is more than or equal to 40 percent, and the preferred residual carbon content is more than or equal to 46 percent.

6. According to the claimsThe surface-modified zinc alkyl phosphinate flame retardant of any one of claims 1 to 5, characterized in that C is_1-2The zinc alkyl phosphinate is zinc methyl ethyl phosphinate and/or zinc diethyl phosphinate, and is preferably zinc methyl ethyl phosphinate.

7. The zinc alkyl phosphinate flame retardant of any one of claims 1 to 6, characterized in that the silane coupling agent comprises one or a combination of two or more of gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane and gamma- (methacryloyloxy) propyltrimethoxysilane, preferably gamma-aminopropyltriethoxysilane.

8. A modified polycarbonate comprising the surface-modified zinc alkyl phosphinate flame retardant of any one of claims 1 to 7.

9. The modified polycarbonate of claim 8, wherein the surface-modified zinc alkyl phosphinate flame retardant is present in the modified polycarbonate in an amount of from 5% to 20%, preferably from 9% to 10% by weight.

10. The modified polycarbonate according to claim 8 or 9, wherein the modified polycarbonate is prepared by:

drying the polycarbonate and the surface-modified zinc alkyl phosphinate flame retardant, and mixing in a high-speed mixer to obtain a mixture;

and extruding the mixture through a double-screw extruder, cooling, drying, granulating and drying to obtain the composite material.

Technical Field

The invention belongs to the field of composite materials, and particularly relates to a surface-modified zinc alkyl phosphinate flame retardant and modified polycarbonate based on the same.

Background

Polycarbonate (PC) is a thermoplastic plastic with excellent comprehensive properties, and is widely used in various fields such as automobile parts, electronic and electrical appliances, mechanical parts and the like because of having good mechanical properties, high and low temperature resistance, electrical insulation and the like. However, carbonate bonds in PC are sensitive to water, acid and heat, so that the PC is easy to age, degrade, yellow and the like in the processing process, and is not beneficial to use; in addition, when the PC is applied to the industries of electronics, electrical, automobiles, buildings and the like, stricter flame retardant performance is often needed, and the PC needs to be modified to improve the flame retardant grade to V-0 grade.

The flame retardants commonly used in PC are brominated, phosphorus/phosphine, phosphorus/phosphazene, silicon, and sulfonate flame retardants. Most of flame retardants applied to PC in the market at present are sulfonate flame retardants, and the flame retardant has the advantages of small addition amount and obvious flame retardant effect.

Commonly used sulfonate-type flame retardants are mainly potassium 3-benzenesulfonyl benzenesulfonate (KSS), potassium perfluorobutyl sulfonate (PPFBS), and sodium 2,4, 5-trichlorobenzenesulfonate (STB). The KSS has a wide application range, does not contain halogen, cannot meet the requirement of preparing thin-walled products when used alone, and needs to be compounded with flame retardants such as polysiloxane and the like, so that the product cost is greatly increased; the PPFBS and STB contain halogen, which has high flame retardant efficiency, but cause environmental hazards during use, and particularly, the use of such flame retardants is increasingly restricted with the implementation of the RoHS directive and REACH regulation of the european union.

The zinc alkyl phosphinate is used as a phosphine flame retardant, is halogen-free and environment-friendly, and can endow the material with good flame retardance after being added into PC, but researches show that the PC material added with the zinc alkyl phosphinate is easy to degrade in the processing process, so that the yellowing phenomenon is generated.

Disclosure of Invention

Problems to be solved by the invention

Aiming at the defects of the polycarbonate added with the zinc alkyl phosphinate in the field in the aspect of processability, the invention provides the surface modified zinc alkyl phosphinate flame retardant, which has the advantages of improved thermal stability and residual carbon content, improved flame retardant property and capability of endowing the polycarbonate with good processability.

Furthermore, the invention also provides modified polycarbonate, which is modified by the alkyl zinc phosphinate flame retardant, so that the processing stability is improved, and the degradation phenomenon can be reduced.

Means for solving the problems

The invention utilizes silane coupling agent pair C_1-2The alkyl zinc phosphinate is subjected to surface modification to obtain the modified flame retardant with high thermal stability and high carbon residue, and the modified flame retardant is applied to polycarbonate, so that the processability of the polycarbonate can be improved, and the technical problem can be solved.

[1]Firstly, the invention provides a surface-modified zinc alkyl phosphinate flame retardant, the zinc alkyl phosphinate flame retardant is obtained by surface modification through a silane coupling agent, and the zinc alkyl phosphinate is C_1-2Zinc alkyl phosphinate.

[2] The surface-modified zinc alkyl phosphinate flame retardant of [1], the surface modification comprising the steps of: mixing the silane coupling agent with the zinc alkyl phosphinate in a solvent, the silane coupling agent hydrolyzing to surface modify the zinc alkyl phosphinate.

[3] The surface-modified zinc alkyl phosphinate flame retardant according to [1] or [2], the surface modification comprising the steps of:

dispersing the zinc alkyl phosphinate in an aqueous solvent to obtain a mixed solution I;

dispersing the silane coupling agent in an anhydrous solvent to obtain a mixed solution II;

and mixing the mixed solution II with the mixed solution I, heating to 60-100 ℃, and adjusting the pH value to 9-10 to obtain the composite material.

[4] The surface-modified zinc alkyl phosphinate flame retardant according to any one of [1] to [3], having a property satisfying one or a combination of two or more of the following conditions:

Td_5％at a temperature above 460 ℃;

Td_10％above 470 ℃.

[5] The surface-modified zinc alkyl phosphinate flame retardant according to any one of [1] to [4], having a property satisfying one or a combination of two or more of the following conditions:

Td_5％at a temperature above 485 ℃;

Td_10％above 495 ℃.

[6] The surface-modified zinc alkyl phosphinate flame retardant according to any one of [1] to [5], having a property satisfying one or a combination of two or more of the following conditions:

[7] the surface-modified zinc alkyl phosphinate flame retardant according to any one of [1] to [6], having a property satisfying one or a combination of two or more of the following conditions:

[8] the surface-modified zinc alkyl phosphinate flame retardant according to any one of [1] to [7], having properties satisfying the following conditions:

the residual carbon content is more than or equal to 40 percent.

[9] The surface-modified zinc alkyl phosphinate flame retardant according to any one of [1] to [8], having properties satisfying the following conditions:

the residual carbon content is more than or equal to 46 percent.

[10]According to [1]]To [9]]The surface-modified zinc alkyl phosphinate flame retardant of any one of, C_1-2The zinc alkyl phosphinate is zinc methyl ethyl phosphinate and/or zinc diethyl phosphinate.

[11]According to [1]]To [10 ]]The surface-modified zinc alkyl phosphinate flame retardant of any one of, C_1-2The zinc alkyl phosphinate is zinc methyl ethyl phosphinate.

[12] The surface-modified zinc alkyl phosphinate flame retardant of any one of [1] to [11], the silane coupling agent comprising one or a combination of two or more of gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and gamma- (methacryloyloxy) propyltrimethoxysilane.

[13] The surface-modified zinc alkyl phosphinate flame retardant of any one of [1] to [12], the silane coupling agent being gamma-aminopropyltriethoxysilane.

[14] Further, the present invention provides a modified polycarbonate comprising the surface-modified zinc alkylphosphinate flame retardant as described in any one of [1] to [13].

[15] The modified polycarbonate according to [14], wherein the surface-modified zinc alkyl phosphinate flame retardant is present in the modified polycarbonate in an amount of 5 to 20% by mass.

[16] The modified polycarbonate according to [14] or [15], wherein the mass fraction of the surface-modified zinc alkylphosphinate flame retardant in the modified polycarbonate is from 9% to 10%.

[17] The modified polycarbonate according to any one of [14] to [16], which is produced by:

drying the polycarbonate and the surface-modified zinc alkyl phosphinate flame retardant, and mixing in a high-speed mixer to obtain a mixture;

and extruding the mixture through a double-screw extruder, cooling, drying, granulating and drying to obtain the composite material.

ADVANTAGEOUS EFFECTS OF INVENTION

The surface modified zinc alkyl phosphinate flame retardant provided by the invention is prepared by coupling silane coupling agent to C_1-2The surface of the zinc alkyl phosphinate is modified, the thermal decomposition temperature is greatly increased, the stability of the polycarbonate matrix material under the action of higher processing temperature and higher shearing force can be improved, and the matrix material is prevented from being degraded and yellowed. In addition, the surface-modified zinc alkyl phosphinate flame retardant has better carbon forming property, and the flame retardant effect of the matrix material on a condensed phase is improved; meanwhile, the surface energy of the surface-modified zinc alkyl phosphinate flame retardant is reduced, the agglomeration property is reduced, the dispersibility of the flame retardant in a matrix material is improved, and the flame retardant has a more excellent flame retardant property macroscopically, so that the flame retardant becomes a choice for the flame retardant in a thin-walled workpiece of a halogen-free flame-retardant polycarbonate matrix material.

Furthermore, the surface-modified zinc alkyl phosphinate flame retardant provided by the invention selects a silane coupling agent as a surface modifier, and is cheap, easy to obtain and environment-friendly.

Furthermore, the modified polycarbonate provided by the invention is stable under the action of higher processing temperature and higher shearing force by adding the surface-modified zinc alkyl phosphinate flame retardant, so that the yellowing phenomenon caused by degradation is avoided, the compounding effect of the silicon flame retardant and the phosphine flame retardant is fully utilized, and the flame retardant efficiency is high.

Detailed Description

Various exemplary embodiments, features and aspects of the invention will be described in detail below. The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In other instances, methods, means, devices and steps which are well known to those skilled in the art have not been described in detail so as not to obscure the invention.

All units used in the specification are international standard units unless otherwise stated, and numerical values and numerical ranges appearing in the present invention should be understood to include systematic errors inevitable in industrial production.

In the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

< first aspect >

In a first aspect of the invention, there is provided a surface-modified zinc alkyl phosphinate flame retardant obtained by surface modification with a silane coupling agent, the zinc alkyl phosphinate being C_1-2Zinc alkyl phosphinate.

The alkyl phosphinate is a phosphine flame retardant, is halogen-free and environment-friendly, and can be added into high polymer materials such as polycarbonate, polyamide and the like to endow the base material with good thermal stability and flame retardance. However, in practical application, different alkyl phosphinates have different pyrolysis mechanisms and different thermal stability in polycarbonate, for example, some alkyl phosphinates are easy to cause degradation of polycarbonate during processing to generate yellowing phenomenon.

The inventors of the present invention found for the first time that the reason for the deterioration of processability of the polycarbonate base material is:when containing C_1-2Polycarbonate of zinc alkyl phosphinate under high temperature high shear processing conditions, C_1-2Zinc alkyl phosphinate has poor stability and is easily decomposed to release acidic substances such as phosphoric acid and phosphoric acid ester, thereby causing ester bond cleavage of the matrix material. The invention utilizes silane coupling agent pair C_1-2The surface modification is carried out on the zinc alkyl phosphinate, the thermal stability and the carbon residue of the obtained modified flame retardant are improved, the flame retardant property is improved, and the addition of the modified flame retardant to polycarbonate can help to reduce or avoid the yellowing phenomenon caused by the degradation of the polycarbonate under the processing conditions.

[ raw materials ]

The surface-modified zinc alkyl phosphinate flame retardant of the present invention comprises C_1-2Zinc alkyl phosphinate and silane coupling agents. Specifically, the method comprises the following steps:

_1-2c alkyl zinc phosphinate

In some preferred embodiments of the invention, C_1-2The zinc alkyl phosphinate is zinc methyl ethyl phosphinate (Zn-MEP) and/or zinc diethyl phosphinate.

In some more preferred embodiments of the invention, C_1-2The zinc alkyl phosphinate is zinc methyl ethyl phosphinate (Zn-MEP).

Silane coupling agent

The silane coupling agent has the greatest characteristic of containing two groups with different chemical properties, wherein one group is a hydrophilic polar group and is easy to chemically react with the surface of an inorganic substance; the other is a hydrophobic non-polar group which is easily chemically reacted with synthetic resin or other polymers. Therefore, the silane coupling agent is called a "molecular bridge" to improve the interfacial action between inorganic and organic substances, thereby greatly improving the performance of the composite material.

In some preferred embodiments of the present invention, the silane coupling agent comprises one or two of gamma-aminopropyltriethoxysilane (trade designation KH550), gamma-glycidoxypropyltrimethoxysilane (trade designation KH560) and gamma- (methacryloyloxy) propyltrimethoxysilane (trade designation KH570)A combination of (a) and (b). The invention utilizes the hydrolysate pair C of the silane coupling agent_1-2The surface of the zinc alkyl phosphinate is modified to improve C_1-2The thermal stability and the carbon forming property of the zinc alkyl phosphinate reduce the release of acidic substances caused by decomposition under the action of high-temperature and high-shear force, on one hand, the zinc alkyl phosphinate is beneficial to improving the stability of a polycarbonate matrix material in processing, preventing the polycarbonate matrix material from being degraded and yellowed and improving the optical transmittance of the material; on the other hand, the compounding effect of the silicon flame retardant and the phosphine flame retardant can be utilized to improve the flame retardant efficiency, so that the flame retardant property of the polycarbonate matrix material can reach the V-0 grade.

In some more preferred embodiments of the invention, the silane coupling agent is gamma-aminopropyltriethoxysilane, such silane coupling agent pair C being comparable to the other two surface modifying agents described above_1-2The zinc alkyl phosphinate has the best surface modification effect, the largest thermal decomposition temperature and carbon formation promotion range, the highest stability promotion range and the most obvious reduction of agglomeration.

With respect to the content of each component in the surface-modified zinc alkyl phosphinate flame retardant, in some specific embodiments of the present invention, the silane coupling agent has a mass C_1-23-5% of the mass of the zinc alkyl phosphinate. If the content of the silane coupling agent is less than 3%, the content of the P-type epoxy resin is adjusted to C_1-2The surface modification of the zinc alkyl phosphinate is incomplete, so that the polycarbonate still has yellowing phenomenon during processing and cannot achieve good flame retardant effect; if the content of the silane coupling agent is more than 5%, the mechanical properties of the base material are affected, and the cost is increased. Illustratively, the ratio may be 3%, 4%, 5%.

In some preferred embodiments of the invention, the mass of the silane coupling agent is 4% of the mass of the zinc methylethylphosphinate.

[ surface modification ]

In some embodiments of the present invention, C is treated for good surface modification_1-2The surface modification of the zinc alkyl phosphinate comprises the following steps: the silane coupling agent is mixed with the zinc alkyl phosphinate in a solvent, and the silane coupling agent is hydrolyzed to modify the surface of the zinc alkyl phosphinate.

Since the degree of hydrolysis of the silane coupling agent directly affects the surface modification effect, in order to promote the hydrolysis to be better carried out, in some specific embodiments of the present invention, for C_1-2The surface modification of zinc phosphinate comprises the following steps:

c is to be_1-2Dispersing zinc alkyl phosphinate in an aqueous solvent to obtain a mixed solution I;

dispersing a silane coupling agent in an anhydrous solvent to obtain a mixed solution II;

and mixing the mixed solution II with the mixed solution I, heating to 60-100 ℃, and adjusting the pH value to 9-10 to obtain the composite material.

The dispersing solvent is not particularly limited in the present invention, but considering that the dispersing effect of the raw materials in the solvent will affect the progress of the hydrolysis reaction and the surface modification effect, in some preferred embodiments of the present invention, the aqueous solvent used in the preparation of the mixed solution is a mixed solvent of deionized water and absolute ethyl alcohol; and when preparing the mixed solution II, the used anhydrous solvent is absolute ethyl alcohol. The proper solvent is selected to improve the dispersion effect of the raw materials.

The invention is not particularly limited with respect to the ratio of the materials in the surface modification process. In some preferred embodiments of the invention, C_1-2The mass ratio of the zinc alkyl phosphinate to the silane coupling agent to the deionized water to the two-part absolute ethyl alcohol is 100 (3-5) to (80-120) to (600-800), and illustratively, the mass ratio may be 100:3:80:600, 100:4:100:700, 100:5:120:800, and the like, and is preferably 100:4:100: 700; wherein the mass ratio of the first prepared mixed solution to the absolute ethyl alcohol used for preparing the second mixed solution is 5: 2.

For temperature control during surface modification, in some embodiments of the invention, the temperature is from 60 to 100 deg.C, preferably from 85 to 100 deg.C. Illustratively, the above temperatures may be 60 ℃, 65 ℃, 70 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃ and the like.

Based on the above-mentioned several optional embodiments, the present invention further prefers that the surface modification method comprises the following steps:

c is to be_1-2Alkyl radicalAdding zinc phosphonate into a mixed solvent of deionized water and absolute ethyl alcohol to obtain a mixed solution I;

adding a silane coupling agent into absolute ethyl alcohol to obtain a mixed solution II;

adding the mixed solution II into the mixed solution I, heating to 85-100 ℃, adjusting the pH value to 9-10, and stirring to obtain a modified mixed solution;

filtering the modified mixed solution, and drying to obtain the modified mixed solution;

wherein, C_1-2The mass ratio of the zinc alkyl phosphinate to the silane coupling agent to the deionized water to the anhydrous ethanol is 100 (3-5) to 80-120 (600-800), and the mass ratio of the prepared mixed solution I to the anhydrous ethanol used for preparing the mixed solution II is 5: 2.

Further, the present invention provides in a more preferred embodiment, the surface modification step comprises the steps of:

sequentially adding C into a three-neck flask with a condenser_1-2Heating zinc alkyl phosphinate, deionized water and absolute ethyl alcohol to 60-70 ℃, fully stirring and dispersing at the stirring speed of 300-350 rpm for 25-35 min to obtain a mixed solution I;

uniformly mixing a silane coupling agent and absolute ethyl alcohol to obtain a mixed solution II;

dropwise adding the mixed solution II into a three-neck flask, maintaining the stirring speed at 300-350 rpm, heating to 85-100 ℃ after dropwise adding, simultaneously adding ammonia water to adjust the pH value to 9-10, and continuously stirring for 2.5-3.5 hours to obtain a modified mixed solution;

and after the reaction is finished, filtering the modified mixed solution, collecting the filtrate, decompressing, pumping out the solvent, and then putting the filtrate into a 120 ℃ blast oven for drying to obtain the modified mixed solution.

Wherein, C_1-2The mass ratio of the zinc alkyl phosphinate to the silane coupling agent to the deionized water to the anhydrous ethanol is 100:4:100:700, and the mass ratio of the prepared mixed solution I to the anhydrous ethanol used for preparing the mixed solution II is 5: 2.

In the preparation of the mixed solution I, for the dispersion temperature, in some specific embodiments of the invention, the temperature is raised to 60-70 ℃ and the mixed solution I is obtained after stirring. Temperature riseHelp to quickly connect C_1-2The zinc alkyl phosphinate is uniformly dispersed in the mixed solvent, so that the temperature is conveniently raised to the reaction temperature in a short time at the later stage, and the preparation efficiency is improved. Illustratively, the above temperatures may be 60 ℃, 62 ℃, 64 ℃, 65 ℃, 66 ℃, 68 ℃, 70 ℃, etc.

In the first step of preparing the mixed solution, the stirring speed and the stirring time are respectively 300-350 rpm and 25-35 min in some specific embodiments of the invention. Illustratively, the agitation rate may be 300rpm, 325rpm, 350rpm, etc.; the stirring time can be 25min, 30min and 35 min. In some preferred embodiments of the invention, the stirring rate is 300rpm and the stirring time is 30 min.

In preparing the modified mixed solution, as for the stirring rate, in some specific embodiments of the present invention, the stirring rate is 300 to 350rpm, and for example, the stirring rate may be 300rpm, 325rpm, 350rpm, or the like. If the stirring speed is lower than 300rpm, the dispersion is not easy, the uniformity of surface modification is influenced, and aggregation is easy to occur; if the stirring speed is higher than 350rpm, the shearing force in the container is too high, and the surface modification efficiency is influenced.

In the preparation of the modified mixed solution, as for the reaction temperature, in some specific embodiments of the present invention, the temperature is raised to 85 to 100 ℃ after the completion of the dropwise addition, and for example, the temperature may be 85 ℃, 90 ℃, 100 ℃, and the like, and preferably 90 ℃.

In the preparation of the modified mixed solution, the pH value is adjusted to 9-10 in some specific embodiments of the invention, and may be, for example, 9, 9.5, 10, etc. And ammonia water is adopted to adjust the pH value, so that the post-treatment is convenient.

When the pH adjustment is completed, in some specific embodiments of the present invention, the stirring is continued for 2.5 to 3.5 hours, and for example, the stirring time may be 2.5 hours, 3 hours, 3.5 hours, and preferably 3 hours. If the reaction time is too short, the reaction is incomplete, and the surface modification effect is poor; if the reaction time is too long, the cost is increased.

[ Performance requirements ]

The surface-modified zinc alkyl phosphinate flame retardant provided by the invention can be applied to modified polycarbonate. By adding the surface-modified zinc alkyl phosphinate flame retardant into polycarbonate, the flame retardant can be kept stable under the action of high temperature and high shear force, the yellowing phenomenon caused by degradation is avoided, the compounding effect of a silicon flame retardant and a phosphine flame retardant is fully utilized, and the flame retardant efficiency is high.

The performance of the surface modified zinc alkyl phosphinate flame retardant of the invention should meet the following conditions:

in some specific embodiments of the present invention, the thermal decomposition temperature (Td) of the surface-modified zinc alkyl phosphinate flame retardant of the present invention should satisfy one or a combination of two or more of the following conditions:

Td_5％at a temperature above 460 ℃;

Td_10％at a temperature above 470 ℃;

one or a combination of two or more of the following conditions should further be satisfied:

Td_5％at a temperature above 485 ℃;

Td_10％above 495 ℃.

In some preferred embodiments of the present invention, the surface-modified zinc alkyl phosphinate flame retardant of the present invention should also have a specific particle size distribution that satisfies one or a combination of two or more of the following conditions:

one or a combination of two or more of the following conditions should further be satisfied:

in some more preferred embodiments of the present invention, the surface-modified zinc alkyl phosphinate flame retardant of the present invention should also have a specific carbon residue, specifically, the carbon residue should satisfy the following condition:

the residual carbon content is more than or equal to 40 percent.

Further, the residual carbon content is more than or equal to 46 percent.

In some more preferred embodiments of the present invention, the surface-modified zinc alkyl phosphinate flame retardant of the present invention should have properties that satisfy one or a combination of two or more of the following conditions:

Td_5％491.3 ℃ is adopted;

Td_10％501.0 ℃ is adopted;

23.05 μm;

3.67 μm;

the residual carbon content was 47.1%.

< second aspect >

In a second aspect of the invention, there is provided a modified polycarbonate comprising the above surface-modified zinc alkyl phosphinate flame retardant.

In some specific embodiments of the present invention, in the modified polycarbonate, when the mass fraction of any one of the surface-modified zinc alkyl phosphinate flame retardants is 5 to 20%, the modified polycarbonate can be kept stable under the action of high temperature and high shear force, so as to avoid yellowing caused by degradation, and the flame retardant efficiency is high by fully utilizing the compounding effect of the silicon flame retardant and the phosphine flame retardant. If the content of the surface-modified zinc alkyl phosphinate flame retardant is lower than 5 percent, a good flame retardant effect cannot be achieved; if the content of the surface-modified zinc alkyl phosphinate flame retardant is higher than 20%, the cost is increased, and the mechanical properties of the matrix material are affected.

In some preferred embodiments of the present invention, in the modified polycarbonate, the mass fraction of any one of the surface-modified zinc alkyl phosphinate flame retardants is 9 to 10%, and illustratively, the mass fraction may be 9%, 9.3%, 9.5%, 9.7%, 10%, and the like.

In some specific embodiments of the invention, gamma-aminopropyltriethoxysilane modified zinc methylethylphosphinate is selected and added to polycarbonate, and when the mass fraction of the gamma-aminopropyltriethoxysilane modified zinc methylethylphosphinate is 9%, the flame retardant performance of the modified polycarbonate material can reach UL 94V-0 grade.

The modified polycarbonate provided by the invention is prepared by the following method:

drying the polycarbonate and the surface-modified zinc alkyl phosphinate flame retardant, and mixing in a high-speed mixer to obtain a mixture;

extruding the mixture through a double-screw extruder, cooling, air-drying, granulating and drying to obtain the composite material;

wherein the mass ratio of the alkyl zinc phosphinate flame retardant polycarbonate is (9-10) to (90-91).

In some preferred embodiments of the present invention, there is further included a step of forming the modified polycarbonate in a pellet form by a press vulcanizer.

In some more preferred embodiments of the invention, the following steps are included:

drying the polycarbonate in a vacuum oven at 80-100 ℃ for 24-48 hours, and drying the surface-modified zinc alkyl phosphinate in the vacuum oven at 80-100 ℃ for 4-8 hours; weighing dry polycarbonate and the surface-modified zinc alkyl phosphinate flame retardant according to the mass percentage, and mixing for 3-5 min at room temperature in a high-speed mixer to obtain a mixture;

adding the mixture into a feeding port of a double-screw extruder, controlling the rotating speed of the double-screw extruder to be 100rpm and the processing temperature to be 210-270 ℃, wherein the temperature of an extrusion section is 265-270 ℃, and cooling, air-drying, granulating and drying the extruded material passing through the double-screw extruder to obtain granular modified polycarbonate;

preheating the granular modified polycarbonate on a flat vulcanizing machine for 5 minutes, then exhausting for 10-15 times, carrying out hot pressing for 1 minute under 10MPa, and then carrying out cold pressing for 1 minute under 5MPa to obtain the flaky modified polycarbonate. Wherein, the temperature of the upper hot plate and the lower hot plate is 270 ℃ and 270 ℃ respectively during hot pressing, and the temperature is room temperature during cold pressing.

Wherein the mass ratio of the dried surface-modified zinc alkyl phosphinate flame retardant to the polycarbonate is (9-10) to (90-91).

Preparation of the mixture

When the mixture is prepared, the interference of water vapor in the raw materials on the processing of the polycarbonate can be eliminated by drying the raw materials of the polycarbonate and the surface-modified alkyl zinc phosphinate flame retardant. The degradation of polycarbonate is mainly caused by two reasons: first, the above-mentioned acid releasing factors; secondly, raw materials are not dried, so that water vapor is generated in the processing process, and the water vapor promotes ester bonds of the polycarbonate to be broken, so that degradation is initiated. If the raw materials are dried and the degradation yellowing phenomenon still occurs during the preparation of the modified polycarbonate, the degradation phenomenon can be concluded to be caused by the release of an acid source under the action of high temperature and high shear of the zinc alkyl phosphinate flame retardant.

In some specific embodiments of the present invention, the drying temperature of the polycarbonate is 80 to 100 ℃, and for example, the drying temperature may be 80 ℃, 90 ℃, 100 ℃, or the like; the drying time is 24 to 48 hours, and illustratively, the drying time may be 24 hours, 30 hours, 36 hours, 42 hours, 48 hours, or the like.

In some specific embodiments of the present invention, the drying temperature of the surface-modified zinc alkyl phosphinate flame retardant is 80 to 100 ℃, and for example, the drying temperature may be 80 ℃, 90 ℃, 100 ℃, and the like; the drying time is 4 to 8 hours, and illustratively, the drying time may be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or the like.

In some specific embodiments of the present invention, the high speed mixer has a rotation speed of 100rpm, a mixing time of 3 to 5min and a mixing temperature of room temperature, and the purpose of the present invention is to uniformly disperse the components. Illustratively, the mixing time may be 3 minutes, 4 minutes, 5 minutes, and the like.

Preparation of modified polycarbonate

In some specific embodiments of the present invention, in the extruding step, the processing temperature of the twin-screw extruder is 210 to 270 ℃, wherein the temperatures of the first zone to the ninth zone of the twin-screw extruder are set to 210 ℃, 230 ℃, 245 ℃, 255 ℃, 265 ℃ and 265 ℃, respectively, and the head temperature is 270 ℃. The temperature of each zone can deviate from 1 to 5 ℃. Wherein the temperature of the extrusion section is preferably 265-270 ℃.

Examples

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

EXAMPLE 1 preparation of surface-modified Zinc alkyl phosphinate flame retardants

Sequentially adding zinc methyl ethyl phosphinate, deionized water and absolute ethyl alcohol into a three-neck flask with a condenser, heating to 65 ℃, and fully stirring at the stirring speed of 300rpm for 30min to obtain a mixed solution I;

uniformly mixing a silane coupling agent and absolute ethyl alcohol to obtain a mixed solution II;

adding the mixed solution into a three-neck flask in a dropwise manner, maintaining the stirring speed at 300rpm, heating to 90 ℃ after the dropwise addition is finished, adding ammonia water to adjust the pH value to be about 10.0, and continuously stirring for 3 hours to obtain a modified mixed solution;

and after the reaction is finished, filtering the modified mixed solution, collecting filtrate, decompressing, pumping out the solvent, and then putting the filtrate into a 120 ℃ forced air oven for drying to obtain the surface modified methyl ethyl zinc phosphinate flame retardant.

The mass ratio of the methyl ethyl zinc phosphinate to the silane coupling agent to the deionized water to the anhydrous ethanol is 100:4:100:700, wherein the mass ratio of the anhydrous ethanol used for preparing the mixed solution I to the anhydrous ethanol used for preparing the mixed solution II is 5: 2.

According to the preparation method, the methyl ethyl zinc phosphinate flame retardants with KH550, KH560 and KH570 surface modified are named as 55-Zn, 56-Zn and 57-Zn respectively.

Example 2

The raw material formula is as follows: 900g of polycarbonate, 55-Zn 100 g;

the preparation method comprises the following steps:

1. drying the polycarbonate in a vacuum oven at 90 ℃ for 24 hours to obtain dried polycarbonate;

2. drying the surface-modified zinc methyl ethyl phosphinate in a vacuum oven at 100 ℃ for 5 hours to obtain dried surface-modified zinc methyl ethyl phosphinate;

3. mixing the dried polycarbonate and the dried surface-modified zinc methyl ethyl phosphinate in a high-speed mixer for 3min at room temperature according to the gram number, so that the components are uniformly dispersed to obtain a mixture;

4. adding the mixture into a feeding port of a double-screw extruder, setting the temperatures of a first zone to a ninth zone of the double-screw extruder to be 210 ℃, 230 ℃, 245 ℃, 255 ℃, 265 ℃ and 265 ℃, setting the head temperature to be 270 ℃ and the rotating speed to be 100rpm, and cooling, air-drying, granulating and drying the extruded material of the double-screw extruder to obtain the modified polycarbonate;

5. preheating the granular modified polycarbonate on a flat vulcanizing machine for 5 minutes, then exhausting for 10-15 times, carrying out hot pressing for 1 minute under 10MPa, and then carrying out cold pressing for 1 minute under 5MPa to obtain the flaky modified polycarbonate. Wherein, during hot pressing, the temperatures of the upper hot plate and the lower hot plate are 270 ℃ and 270 ℃ respectively; at cold pressing, the temperature is room temperature.

Example 3

The raw material formula is as follows: polycarbonate 900g, 56-Zn 100 g;