CN114716826B - PPS/PA blend biaxially oriented film and preparation method thereof - Google Patents

Abstract

The application discloses a PPS/PA blend biaxially oriented film and a preparation method thereof, wherein the PPS/PA blend biaxially oriented film comprises 60-70% of PPS resin, 12-18% of PA resin, 1-1.2% of antioxidant, 14.8-18% of heat conducting filler and 2-3% of lubricant: 2-3% of other auxiliary agents, wherein the heat conducting filler comprises boron nitride nano-sheets and nano-magnesia. The preparation method of the film comprises the following steps: drying the PPS resin; mixing PA, an antioxidant, dried PPS resin, a heat conducting filler, a lubricant and other auxiliary agents according to a proportion, and extruding and granulating to obtain modified PPS resin; and (3) carrying out melt casting on the modified PPS resin to obtain a sheet, and then carrying out biaxial stretching on the sheet to obtain the PPS/PA blend biaxially oriented film. The PPS/PA blend biaxially oriented film has good film forming performance, and meanwhile has heat conducting performance, so that the service life of the low-loss capacitor is prolonged.

Description

PPS/PA blend biaxially oriented film and preparation method thereof

Technical Field

The application relates to the field of film materials, in particular to a PPS/PA blend biaxially oriented film and a preparation method thereof.

Background

Polyphenylene sulfide, abbreviated as PPS in English, has a melting point as high as 280-290 ℃ and a decomposition temperature of more than 400 ℃, has the advantages of high temperature resistance, corrosion resistance, radiation resistance, incombustibility, no toxicity, excellent mechanical properties, excellent electrical properties and the like, and is thermoplastic crystalline resin with excellent comprehensive properties. Among them, the PPS resin has a small influence of temperature and frequency on dielectric constant and dielectric loss, and the PPS film produced using the PPS resin has excellent electrical properties and can be used for low-loss capacitors.

At present, the PPS film is generally prepared by biaxially stretching PPS, which is beneficial to improving the tensile strength of the PPS film. However, PPS molecular chains are rigid, the crystallinity can reach 75%, and the toughness is poor, so that the PPS biaxially oriented film has a problem of difficulty in film formation.

In the related art, in order to improve the film forming performance of the PPS biaxially oriented film, a PPS/PA blend biaxially oriented film is prepared by blending PPS and PA. Wherein, the incorporation of PA improves the elongation at break of PPS resin, which is beneficial to reducing the difficulty of film formation of PPS resin.

However, the biaxially oriented film of the PPS/PA blend has poor heat conductivity, and when the capacitor heats, the film cannot rapidly conduct heat, thereby causing damage to the capacitor.

Disclosure of Invention

In order to solve the problem that heat cannot be quickly conducted out of a film, so that a capacitor is damaged, the application provides a PPS/PA blend biaxially oriented film and a preparation method thereof.

In a first aspect, the present application provides a biaxially oriented film of PPS/PA blend, which adopts the following technical scheme:

a PPS/PA blend biaxially oriented film is prepared from the following raw materials in percentage by weight:

PPS resin: 60-70%

PA resin: 12-18%

Antioxidant: 1-1.2%

And (3) a heat conducting filler: 14.8-18%

And (3) a lubricant: 2-3%

Other auxiliaries: allowance of

The heat conducting filler comprises boron nitride nanosheets and nano magnesium oxide.

By adopting the technical scheme, the compatibility of the PA resin and the PPS resin is good, and the blending modification is carried out on the PPS resin by adopting the PA resin, so that the elongation at break of the PPS biaxially oriented film is improved, and the film forming difficulty of the PPS biaxially oriented film is reduced.

The boron nitride nano-sheet has good heat conduction performance and stable performance, but has the problems of poor dispersibility and poor compatibility with PPS/PA blend; the heat conduction performance of the nano magnesium oxide is poorer than that of the boron nitride nano sheet, but the dispersion performance of the nano magnesium oxide in the PPS/PA blend is better than that of the boron nitride nano sheet. Wherein, uneven dispersion of the heat conducting filler can have adverse effect on the improvement of the toughness performance of the PPS/PA blend biaxially oriented film. In order to obtain the PPS/PA blend biaxially oriented film with good heat-conducting property and good toughness property, the heat-conducting filler adopts the compound of the boron nitride nanosheets and the nano magnesium oxide, and the dispersion property of the boron nitride nanosheets and the PPS/PA blend is improved under the action of the nano magnesium oxide, so that the PPS/PA blend biaxially oriented film with good toughness property and good heat-conducting property is obtained, the heat of the capacitor is led out quickly, and the service life of the capacitor is prolonged.

In order to better improve the toughness performance of PPS, the PA is selected from any one or two of PA6 resin and PA6 and PA66 copolymer.

Optionally, the heat-conducting filler is prepared from the following raw materials in parts by weight:

boron nitride nanoplatelets: 10-20 parts

Nano magnesium oxide: 40-80 parts

Silane coupling agent: 10-15 parts

Polyethyleneimine: 40-80 parts

Water: 1000 parts.

By adopting the technical scheme, the polyethylene imine and polyamide PA have better compatibility, the silane coupling agent can reduce the interface difference between the boron nitride nanosheets, the nano magnesium oxide and the PPS/PA blend, and the combined action of the two is beneficial to simultaneously improving the dispersion performance of the boron nitride nanosheets and the nano magnesium oxide in the PPS/PA blend, so that the toughness performance of the biaxially oriented film of the PPS/PA blend is further improved.

Optionally, the preparation method of the heat conducting filler comprises the following steps:

dissolving polyethyleneimine and a silane coupling agent in water to obtain a polyethyleneimine-silane coupling agent mixed solution;

adding nano magnesium oxide into the polyethyleneimine-silane coupling agent mixture liquid, and uniformly stirring to obtain coating liquid;

adding boron nitride nano-sheets into the coating liquid, stirring uniformly, vibrating for 1.5-2.5h by ultrasonic, separating solid from liquid, drying and sieving the solid to obtain the heat-conducting filler.

By adopting the technical scheme, the polyethylene imine-silane coupling agent mixed solution mixed with the nano magnesium oxide is coated on the outer side of the boron nitride nano sheet, so that the dispersion performance of the boron nitride nano sheet and the nano magnesium oxide can be greatly improved, the heat conducting filler can be uniformly dispersed into the PPS/PA blend, the toughness performance of the PPS/PA blend biaxially oriented film can be further improved, and the film forming performance of the PPS/PA blend biaxially oriented film can be further improved. However, the heat conduction performance of the boron nitride nano sheet coated by the polyethylenimine is reduced, but the application can form a complete heat conduction network by mixing the nanometer magnesia in the polyethylenimine-silane coupling agent mixed solution, so that the introduction of the polyethylenimine can not cause obvious adverse effect on the heat conduction performance of the PPS/PA blend biaxially oriented film.

Optionally, the boron nitride nanosheets are porous boron nitride nanosheets, and the preparation method of the porous boron nitride nanosheets comprises the following steps:

adding boric acid with the concentration of 0.5-0.6mol/L and melamine with the concentration of 0.005-0.008 mol/L into a container, stirring until white jelly is generated, and heating the mixed solution in the container in a water bath, wherein the temperature of the water bath is controlled at 85-90 ℃; wherein the molar ratio of boric acid to melamine is (2.0-2.2): 1;

after the mixed solution in the container becomes clear and transparent, preserving heat for 1-2 hours at 68-72 ℃, then cooling to 40-45 ℃, preserving heat for 1-2 hours, then naturally cooling to room temperature, and gradually generating white floccules by the clear and transparent mixed solution; filtering to separate white floccules, washing the white floccules with deionized water, and drying at 80-85 ℃ to obtain boron nitride precursors;

calcining the boron nitride precursor for 5-6 hours at 1300-1500 ℃ in a nitrogen atmosphere of 300-400 mL/min to obtain the porous boron nitride nanosheets.

By adopting the technical scheme, when the porous boron nitride nanosheets are prepared according to the method, the surface roughness of the porous boron nitride nanosheets is larger, and the bonding fastness of the polyethylenimine-silane coupling agent solution and the boron nitride nanosheets is further improved, so that the heat conducting filler with more uniform or better dispersion performance is obtained.

Alternatively, the polyethyleneimine has a viscosity of 5 to 8 ten thousand cps.

By adopting the technical scheme, when the concentration of the polyethyleneimine is 5-8 ten thousand cps, the bonding fastness of the polyethyleneimine and the boron nitride nanosheets is better, and meanwhile, the dispersion performance of the nano magnesium oxide in the polyethyleneimine is better, thereby being beneficial to the formation of a complete and conductive heat conduction network.

Optionally, the particle size of the heat conducting filler ranges from 800 meshes to 1000 meshes.

By adopting the technical scheme, when the particle size of the heat conducting filler is 800-1000 meshes, the dispersion performance of the heat conducting filler in the PPS/PA blend is best.

Optionally, the antioxidant comprises an antioxidant 1010 and an antioxidant 168, and the weight ratio of the antioxidant 1010 to the antioxidant 168 is 3:2.

by adopting the technical scheme, the antioxidant 1010 is a high molecular weight hindered phenol antioxidant with low volatility, can improve the discoloration resistance of the polymer material under the high-temperature processing condition, and can effectively prevent the thermal oxidative degradation of the polymer material in the long-term aging process. The antioxidant 168 can effectively decompose the hydroperoxide generated in the thermal processing process of the polymeric material, and the antioxidant 1010 can improve the stability of PPS resin and PA resin in the processing process.

Optionally, the lubricant is a silicone masterbatch.

By adopting the technical scheme, the silicone master batch is an ultra-high molecular weight plastic efficient lubricant without an organic carrier, and can improve the processing fluidity of the PPS/PA blend.

Optionally, the other auxiliary agent comprises 1.8-2.2% of an open-ended slipping agent, and the open-ended slipping agent is selected from one or a combination of more of erucamide, talcum powder and silicon dioxide.

By adopting the technical scheme, the addition of the opening slipping agent can improve the opening performance of the PPS/PA blend biaxially oriented film, and the influence of erucamide, talcum powder or silicon dioxide and the like on the dielectric constant and dielectric loss of the PPS/PA blend biaxially oriented film is small.

In a second aspect, the present application further provides a preparation method of a PPS/PA blend biaxially oriented film, which adopts the following technical scheme:

a preparation method of a PPS/PA blend biaxially oriented film comprises the following steps:

s1, drying PPS resin;

s2, mixing PA, an antioxidant, dried PPS resin, a heat conducting filler, a lubricant and other auxiliary agents in a ratio, extruding and granulating to obtain modified PPS resin;

and S3, carrying out melt casting on the modified PPS resin to obtain a sheet, and then carrying out biaxial stretching on the sheet to obtain the PPS/PA blend biaxially oriented film.

By adopting the technical scheme, when the biaxially oriented film of the PPS/PA blend is prepared, the PPS resin is dried, so that the dispersion performance of the PPS resin and other components is improved, a uniform system is obtained, and the quality of the biaxially oriented film of the PPS/PA blend is improved.

Preferably, the preparation method of the PPS/PA blend biaxially oriented film comprises the following steps:

s1, drying PPS resin in a dryer at 110 ℃ for 4 hours to obtain dried PPS resin;

s2, proportionally adding the dried PPS resin, PA, an antioxidant, a heat-conducting filler, a lubricant and other auxiliary agents into a double-screw extruder for extrusion granulation, wherein the temperature of the extruder is as follows: one zone 280+/-2 ℃,2-5 zone 280+/-2 ℃, die head 290+/-2 ℃ and extruder rotating speed: 40+/-2 r/min to obtain modified PPS resin particles, and drying at 80+/-2 ℃ for 4 hours for later use;

s3, putting the modified PPS resin into a single screw extruder, wherein the temperature is set to be 300+/-2 ℃ and the rotating speed is set to be 30+/-2 r/min; extruding the modified PPS melt to a casting roller through a connecting pipe to a die head, wherein the temperature of the casting roller is 130+/-2 ℃, and the die lip clearance and the speed of the casting roller are regulated so that the thickness of the cast sheet is 160+/-10 microns;

s4, feeding the sheet obtained by casting into a synchronous stretching system, wherein specific equipment is a large-sized oven with a rotatable chain clamp, the temperature of the oven is set to 240+/-5 ℃, and the rotating speed of an oven fan is 2500+/-50 r/min; the speed of the chain at the inlet of the oven is 50+/-5 m/min; the running speed of the chain at the outlet is 150+/-5 m/min, and the stretching multiplying power is as follows: each 3 times transverse and longitudinal.

In summary, the present application has the following beneficial effects:

(1) The PPS/PA blend biaxially oriented film has toughness performance and heat conduction performance, and is favorable for rapidly leading out the heat of the capacitor, so that the service life of the capacitor is prolonged.

(2) The compatibility of the polyethylenimine and polyamide PA is good, the silane coupling agent can reduce the interface difference of the boron nitride nanosheets, the nano magnesium oxide and the PPS/PA blend, and the combined action of the two is beneficial to improving the dispersion performance of the boron nitride nanosheets and the nano magnesium oxide in the PPS/PA blend at the same time, so that the toughness performance of the biaxially oriented film of the PPS/PA blend is further improved.

Detailed Description

The present application is described in further detail below in connection with preparation examples, examples and comparative examples.

Preparation example

The proportions (unit: kg) of the respective components of the heat conductive fillers in preparation examples 1 to 10 are shown in Table 1 below.

TABLE 1 proportions of the respective components of the thermally conductive fillers in preparation examples 1 to 10

Preparation example	Boron nitride nanosheets	Nanometer magnesia	Silane coupling agent	Polyethylene imine	Water and its preparation method
						1	20	80	0	0	0
2	10	40	10	40	0
						3	20	80	15	80	0
4	20	80	95	0	0
						5	20	80	0	95	0
6-8	20	80	15	80	1000
						9	20	0	15	80	1000
10	0	80	15	80	1000

Preparation example 1

A thermally conductive filler, the method of making comprising the steps of:

the boron nitride nanosheets and the nano magnesium oxide were uniformly mixed according to the proportions in table 1 to obtain the heat conductive filler.

PREPARATION EXAMPLES 2 to 5

A thermally conductive filler, the method of making comprising the steps of:

uniformly mixing the boron nitride nanosheets, the nano magnesium oxide, the silane coupling agent and the polyethyleneimine according to the proportion in the table 1, and drying to obtain the heat conducting filler.

The silane coupling agent may be KH550 or KH560 or a combination of both, wherein KH550 is used as the silane coupling agent in the present preparation examples 2 to 5.

When the method is adopted to prepare the heat-conducting filler, the dispersibility of the heat-conducting filler is better when the molecular weight of the polyethyleneimine is 5000-10000; wherein the molecular weight of the polyethyleneimine in the preparation example 2 is 10000, and the molecular weight of the polyethyleneimine in the preparation examples 3 and 5 is 5000.

Preparation example 6

A thermally conductive filler, the method of making comprising the steps of:

dissolving polyethyleneimine and a silane coupling agent in water according to the proportion in the table 1 to obtain a polyethyleneimine-silane coupling agent mixed solution;

adding nano magnesium oxide into the polyethyleneimine-silane coupling agent mixture liquid, and uniformly stirring to obtain coating liquid;

adding boron nitride nano-sheets into the coating liquid, stirring uniformly, vibrating for 2 hours by ultrasonic, separating solid from liquid, drying and sieving the solid to obtain the heat-conducting filler with the particle size range of 800-1000 meshes.

When the method is adopted to prepare the heat-conducting filler, the dispersibility of the heat-conducting filler is better when the molecular weight of the polyethyleneimine is 5-8 ten thousand; among them, the molecular weight of polyethyleneimine in this preparation example was 5 ten thousand.

Preparation example 7

A heat conductive filler differs from preparation example 6 in that:

the boron nitride nano-sheet is a porous boron nitride nano-sheet, and the preparation method of the porous boron nitride nano-sheet is as follows:

sa, adding boric acid with the concentration of 0.55mol/L and melamine with the concentration of 0.006mol/L into a container, stirring until white jelly is generated, and heating the mixed solution in the container in a water bath, wherein the temperature of the water bath is controlled at 85 ℃; wherein the molar ratio of boric acid to melamine is 2.1:1;

after the mixed solution in the container becomes clear and transparent, preserving heat for 1.5h at 70 ℃, and naturally cooling to room temperature, wherein the clear and transparent mixed solution gradually generates white floccules; filtering to separate white floccules, washing the white floccules with deionized water, and drying at 82 ℃ to obtain boron nitride precursors;

and Sc, calcining the boron nitride precursor for 5.5 hours at 1400 ℃ in a nitrogen atmosphere of 350mL/min to obtain the porous boron nitride nanosheet.

Preparation example 8

A heat conductive filler differs from preparation example 7 in that:

after the mixed solution in the container becomes clear and transparent, preserving heat for 1.5h at 70 ℃, then cooling to 45 ℃, preserving heat for 1.5h continuously, and then naturally cooling to room temperature; filtering to separate white floccules, washing the white floccules with deionized water, and drying at 82 ℃ to obtain boron nitride precursors;

preparation example 9

A thermally conductive filler, the method of making comprising the steps of:

dissolving polyethyleneimine and a silane coupling agent in water according to the proportion in the table 1 to obtain a polyethyleneimine-silane coupling agent mixed solution; the molecular weight of the polyethyleneimine in the preparation example is 5 ten thousand;

adding boron nitride nano-sheets into the polyethylene imine-silane coupling agent mixed solution, stirring uniformly, performing ultrasonic vibration for 2 hours, performing solid-liquid separation, drying and sieving the solid to obtain the heat-conducting filler with the particle size range of 800-1000 meshes.

Preparation example 10

A thermally conductive filler, the method of making comprising the steps of:

dissolving polyethyleneimine and a silane coupling agent in water according to the proportion in the table 1 to obtain a polyethyleneimine-silane coupling agent mixed solution; the molecular weight of the polyethyleneimine in the preparation example is 5 ten thousand;

adding nano magnesium oxide into the mixture liquid of the polyethylenimine and the silane coupling agent, stirring uniformly, vibrating for 2 hours by ultrasonic, separating solid from liquid, drying and sieving the solid to obtain the heat-conducting filler with the particle size range of 800-1000 meshes.

Examples

The PPS resin in each example of the present application has a melting point of 280℃and is available from Selanis corporation under the trade name 0309; PA6 is derived from basf B32. The above is a selection of the embodiments of the present application, but is not limited to the manufacturer type.

The proportions (unit: kg) of the components of the biaxially oriented film of the PPS/PA blend in examples 1 to 3 are shown in Table 2 below.

Table 2 proportion of the components of the biaxially oriented PPS/PA blend film of examples 1 to 3

Examples	PPS resin	PA6	Antioxidant agent	Heat conductive filler	Silicone master batch
						1	60	18	1	18	3
2	65	15	1	16.5	2.5
						3	70	12	1.2	14.8	2

Examples 1 to 3

The preparation method of the PPS/PA blend biaxially oriented film comprises the following steps:

s1, drying PPS resin in a dryer at 110 ℃ for 4 hours to obtain dried PPS resin

S2, adding the dried PPS resin, PA, an antioxidant, a heat-conducting filler, silicone master batch and other auxiliary agents into a double-screw extruder according to the proportion shown in the table 1 for extrusion granulation, wherein the extruder temperature is as follows: one zone 280 ℃,2-5 zone 280 ℃, die temperature 290 ℃, extruder speed: 40r/min to obtain modified PPS resin particles, and drying at 80 ℃ for 4 hours for later use;

s3, putting the modified PPS resin into a single screw extruder, wherein the temperature is set to 300 ℃ and the rotating speed is 30r/min; extruding the modified PPS melt to a casting roller through a connecting pipe to a die head, wherein the temperature of the casting roller is 130 ℃, and the die lip clearance and the speed of the casting roller are regulated so that the thickness of the cast sheet is 160 micrometers;

s4, feeding the sheet obtained by casting into a synchronous stretching system, wherein specific equipment is a large-sized oven with a rotatable chain clamp, the temperature of the oven is set to 240 ℃, and the rotating speed of an oven fan is 2500r/min; the speed of the chain at the inlet of the oven is 50m/min; the running speed of the chain at the outlet is 150m/min, and the stretching multiplying power is as follows: and 3 times of the transverse direction and the longitudinal direction respectively to obtain the PPS/PA blend biaxially oriented film.

Wherein, in examples 1-3, the heat conductive filler was the heat conductive filler prepared in preparation example 1, the antioxidant comprises antioxidant 1010 and antioxidant 168, and the weight ratio of antioxidant 1010 to antioxidant 168 is 3:2.

Examples 4 to 10

A PPS/PA blend biaxially oriented film, differing from example 2 in that: the preparation methods of the heat conductive fillers were different, wherein the heat conductive fillers of examples 4 to 10 were the heat conductive fillers prepared in preparation examples 2 to 8, respectively, as shown in Table 3 below.

TABLE 3 Heat conductive filler corresponding to examples 4-10

Examples	Heat conductive filler	Examples	Heat conductive filler
				4	Preparation example 2	8	Preparation example 6
5	Preparation example 3	9	Preparation example 7
				6	Preparation example 4	10	Preparation example 8
7	Preparation example 5

Example 11

A PPS/PA blend biaxially oriented film, differing from example 10 in:

2kg of an open-mouth slipping agent was also added, and the amount of PPS resin was 63kg.

Wherein, the opening slipping agent can be selected from one or a combination of more than one of erucamide, talcum powder or silicon dioxide.

Comparative example

Comparative example 1

A PPS/PA blend biaxially oriented film, differing from example 2 in that: the heat conductive filler is replaced by equivalent boron nitride nano-sheets.

Comparative example 2

A PPS/PA blend biaxially oriented film, differing from example 2 in that: the heat conductive filler is replaced by an equivalent amount of nano magnesium oxide.

Comparative example 3

A PPS/PA blend biaxially oriented film, differing from example 2 in that: no thermally conductive filler is added.

Comparative example 4

A PPS/PA blend biaxially oriented film, differing from example 2 in that: the heat conductive filler was replaced with the same amount of the heat conductive filler in preparation example 9.

Comparative example 5

A PPS/PA blend biaxially oriented film, differing from example 2 in that: the heat conductive filler was replaced with the same amount of the heat conductive filler in preparation example 10.

Performance test data

(1) Tensile strength: testing was performed according to ISO 527-1-2012.

(2) Elongation at break: testing was performed according to ISO 527-1-2012.

(3) Shrinkage ratio: GB/T12027-2004 test method for testing the heating dimensional change rate of plastic film and sheet, wherein the test temperature is 150 ℃ and the test time is 30min.

(4) Thermal conductivity coefficient: the test is carried out by referring to GB/T3399-1982 Heat protection plate method of test method for thermal conductivity coefficient of plastics.

TABLE 4 Performance data for the films of examples 1-11 and comparative examples 1-5

Examples	Tensile Strength (MPa)	Elongation at break (%)	Shrinkage (%)	Coefficient of thermal conductivity (W/m.K)
					Example 1	172	31	1.6	0.56
Example 2	174	33	1.6	0.59
					Example 3	170	30	1.7	0.52
Example 4	176	35	1.5	0.60
					Example 5	182	38	1.5	0.60
Example 6	176	35	1.6	0.58
					Example 7	178	36	1.6	0.56
Example 8	185	40	0.9	0.76
					Example 9	198	54	0.7	0.82
Example 10	206	58	0.5	0.96
					Example 11	208	58	0.5	0.98
Comparative example 1	140	20	2.8	0.33
					Comparative example 2	168	28	2.7	0.39
Comparative example 3	185	40	2.9	0.30
					Comparative example 4	170	30	2.2	0.45
Comparative example 5	175	36	2.6	0.33

Example 2 differs from comparative examples 1-3 in that: the heat conductive filler in example 2 was a mixture of boron nitride nanosheets and nano magnesium oxide, the heat conductive filler in comparative example 1 was boron nitride nanosheets alone, the heat conductive filler in comparative example 2 was nano magnesium oxide alone, and the heat conductive filler was not added in comparative example 3.

As is clear from the data shown in table 4, when the boron nitride nanosheets were used alone as the heat conductive filler, the tensile strength and elongation at break of the PPS/PA blend biaxially oriented film were both greatly reduced, and the anti-shrinkage property and heat conductive property of the PPS/PA blend biaxially oriented film were not significantly changed from those of the film without the heat conductive filler. When the nano magnesium oxide is adopted as the heat conducting filler, the anti-shrinkage performance and the heat conducting performance of the PPS/PA blend biaxially oriented film are similar to those of the heat conducting filler which adopts the boron nitride nano sheet alone, and the tensile strength and the elongation at break of the PPS/PA blend biaxially oriented film are reduced compared with those of the film in the embodiment 2, but the reduction amplitude is smaller than that of the film which adopts the boron nitride nano sheet alone.

The inventors analyzed the reason for this as follows: the dispersibility of the boron nitride nano-sheets in the PPS/PA blend is extremely poor, and the dispersibility of the nano-magnesia in the PPS/PA blend is superior to that of the boron nitride nano-sheets, so that when the nano-magnesia is singly adopted as the heat-conducting filler, the influence on the stretching resistance and fracture resistance of the biaxially oriented film of the PPS/PA blend is small; however, the heat conduction performance of nano magnesium oxide is worse than that of boron nitride nano sheet, so when the nano magnesium oxide is singly adopted as the heat conduction filler, the heat conduction performance of the biaxially oriented film of PPS/PA blend can not be improved well under the use level of the nano magnesium oxide. However, the boron nitride nanosheets have good heat conducting performance, but when the boron nitride nanosheets are adopted as the heat conducting filler alone due to poor dispersibility, a complete heat conducting passage cannot be formed, so that the heat conducting performance of the PPS/PA blend biaxially oriented film is not obviously improved.

In the application, the inventor adopts the compound product of the boron nitride nanosheets and the nano magnesium oxide as the heat conducting filler, and simultaneously takes the dispersion property and the heat conducting property of the heat conducting filler into consideration, so that the PPS/PA blend biaxially oriented film with good tensile property, fracture resistance, shrinkage resistance and heat conducting property is obtained.

Example 2 differs from examples 5-7 in that: the heat conductive filler is different. The heat conducting filler in the embodiment 2 is a blend of boron nitride nano-sheets and nano-magnesia, the heat conducting filler in the embodiment 5 is a blend of boron nitride nano-sheets, nano-magnesia, a silane coupling agent and polyethyleneimine, the heat conducting filler in the embodiment 6 is a blend of boron nitride nano-sheets, nano-magnesia and a silane coupling agent, and the heat conducting filler in the embodiment 7 is a blend of boron nitride nano-sheets, nano-magnesia and polyethyleneimine.

It is understood from the data shown in Table 4 that the tensile properties and fracture resistance of the biaxially oriented PPS/PA blend film can be improved by adding the silane coupling agent or the polyethylenimine to the boron nitride nanosheets and the nano magnesium oxide alone or by adding the silane coupling agent and the polyethylenimine to the boron nitride nanosheets and the nano magnesium oxide simultaneously, but the shrinkage resistance and the heat conductivity of the biaxially oriented PPS/PA blend film are not significantly changed.

For this, the inventors analyzed that the cause may be: the silane coupling agent has little effect on improving the dispersion performance of the boron nitride nano-sheet in the PPS/PA blend, and is beneficial to improving the dispersion performance of the heat-conducting filler when the silane coupling agent and the polyethyleneimine are used for modifying the boron nitride nano-sheet and the nano-magnesia together, but the addition of the polyethyleneimine or the silane coupling agent can reduce the heat-conducting performance of the boron nitride nano-sheet and the nano-magnesia, so that the shrinkage resistance and the heat-conducting performance of the PPS/PA blend biaxially oriented film have no obvious change.

Example 5 differs from example 8 in that: the heat conductive filler is different. The heat conductive filler in the embodiment 5 is a blend of boron nitride nanosheets, nano magnesium oxide, a silane coupling agent and polyethyleneimine; the heat conductive filler in the embodiment 8 is further introduced with raw water, and is prepared by uniformly mixing the polyethyleneimine with the silane coupling agent and water to obtain a polyethyleneimine-silane coupling agent mixed solution, uniformly mixing the polyethyleneimine-silane coupling agent mixed solution with nano magnesium oxide to obtain a coating solution, adding the boron nitride nano-sheet into the coating solution, and finally carrying out solid-liquid separation, drying and sieving.

As can be seen from a combination of the data of examples 5 and 8 in table 4: compared with the embodiment 5, the tensile property, the fracture resistance, the shrinkage resistance and the heat conduction property of the biaxially oriented film of the PPS/PA blend in the embodiment 8 are further improved, which proves that the dispersion property of the heat conduction filler is more favorable to be improved when the heat conduction filler is prepared by adopting the method in the embodiment 8, and the formation of a heat conduction network of the biaxially oriented film of the PPS/PA blend is not influenced.

Comparative examples 4 to 5 differ from example 8 in that: in contrast to example 8, no nano magnesium oxide was added in comparative example 4 and no boron nitride nanoplatelets were added in comparative example 5. From the data in Table 4 for example 8 and comparative examples 4-5, it can be seen that the PPS/PA blend biaxially oriented films of comparative examples 4, 5 have significantly reduced shrink resistance and heat conductivity compared to example 8. In this regard, the inventor may analyze that the reason is that when no nano magnesium oxide or boron nitride nano sheet is added in the heat conducting filler, the formation of the complete heat conducting network is not facilitated, so that the anti-shrinkage performance and the heat conducting performance of the PPS/PA blend biaxially oriented film are greatly reduced.

Example 8 differs from example 9 in that: the boron nitride nanoplatelets in example 9 are porous boron nitride nanoplatelets. As can be seen from the data of example 8 and example 9 in table 4, the biaxially oriented film of PPS/PA blend of example 9 has significantly increased tensile properties and elongation at break, further improving the film forming properties of PPS/PA blend, as compared to example 8. Meanwhile, the anti-shrinkage performance and the heat conduction performance of the PPS/PA blend biaxially oriented film are further enhanced, and the reason is probably that the combination fastness of the porous boron nitride nanosheets and the polyethyleneimine-silane coupling agent solution is stronger, so that the dispersion performance of the heat conduction filler is further improved.

Example 9 differs from example 10 in that: example 10 when preparing porous boron nitride nanoplatelets, a two-step cooling mode was employed. As can be seen from the data of example 9 and example 10 in table 4, the properties of the PPS/PA blend biaxially oriented film of example 10 are further improved as compared to example 9, probably due to: when two-step cooling is adopted, the surface roughness of the porous boron nitride nano-sheet is larger, which is beneficial to further improving the bonding fastness of the polyethylenimine-silane coupling agent solution and the boron nitride nano-sheet, thereby obtaining the heat conducting filler with more uniform or better dispersion performance.

Claims (10)

1. The PPS/PA blend biaxially oriented film is characterized by being prepared from the following raw materials in percentage by weight:

PPS resin: 60-70%

PA resin: 12-18%

Antioxidant: 1-1.2%

And (3) a heat conducting filler: 14.8-18%

And (3) a lubricant: 2-3%

Other auxiliaries: allowance of

The heat conducting filler comprises boron nitride nanosheets and nano magnesium oxide.

2. The PPS/PA blend biaxially oriented film according to claim 1, wherein the heat conductive filler is made of raw materials comprising, by weight:

boron nitride nanoplatelets: 10-20 parts

Nano magnesium oxide: 40-80 parts

Silane coupling agent: 10-15 parts

Polyethyleneimine: 40-80 parts

Water: 1000 parts.

3. The biaxially oriented film of PPS/PA blend according to claim 2, wherein the heat conductive filler is prepared by the process comprising:

dissolving polyethyleneimine and a silane coupling agent in water to obtain a polyethyleneimine-silane coupling agent mixed solution;

adding nano magnesium oxide into the polyethyleneimine-silane coupling agent mixture liquid, and uniformly stirring to obtain coating liquid;

adding boron nitride nano-sheets into the coating liquid, stirring uniformly, vibrating ultrasonically, separating solid from liquid, drying and sieving the solid to obtain the heat-conducting filler.

4. A PPS/PA blend biaxially oriented film according to claim 3, wherein: the boron nitride nano-sheet is a porous boron nitride nano-sheet, and the preparation method of the porous boron nitride nano-sheet comprises the following steps:

adding boric acid with the concentration of 0.5-0.6mol/L and melamine with the concentration of 0.005-0.008 mol/L into a container, stirring until white jelly is generated, and heating the mixed solution in the container in a water bath, wherein the temperature of the water bath is controlled at 85-90 ℃; wherein the molar ratio of boric acid to melamine is (2.0-2.2): 1;

after the mixed solution in the container becomes clear and transparent, preserving heat for 1-2h at 68-72 ℃, then cooling to 40-45 ℃, preserving heat for 1-2h continuously, and then naturally cooling to room temperature; filtering to separate white floccules, washing the white floccules with deionized water, and drying at 80-85 ℃ to obtain boron nitride precursors;

calcining the boron nitride precursor for 5-6 hours at 1300-1500 ℃ in a nitrogen atmosphere of 300-400 mL/min to obtain the porous boron nitride nanosheets.

5. A PPS/PA blend biaxially oriented film according to claim 3, wherein said polyethylenimine has a viscosity of 5-8 ten thousand cps.

6. A biaxially oriented film of PPS/PA blend according to claim 3, wherein the particle size of said heat conductive filler is in the range of 800-1000 mesh.

7. A biaxially oriented PPS/PA blend film according to any one of claims 1 to 6, wherein: the antioxidant comprises an antioxidant 1010 and an antioxidant 168, and the weight ratio of the antioxidant 1010 to the antioxidant 168 is 3:2.

8. A biaxially oriented PPS/PA blend film according to any of claims 1-6, wherein the lubricant is silicone master batch.

9. A biaxially oriented PPS/PA blend film according to any one of claims 1 to 6, wherein: the other auxiliary agent comprises 1.8-2.2% of an open-ended slipping agent, wherein the open-ended slipping agent is one or a combination of more than one of erucamide, talcum powder and silicon dioxide.

10. A method for preparing a biaxially oriented PPS/PA blend film according to any one of claims 1 to 9, comprising the steps of:

s1, drying PPS resin;

s2, mixing the PA, the antioxidant, the dried PPS resin, the heat conducting filler, the lubricant and other auxiliary agents according to the proportion, and extruding and granulating to obtain modified PPS resin particles;

and S3, carrying out melt casting on the modified PPS resin to obtain a sheet, and then carrying out biaxial stretching on the sheet to obtain the PPS/PA blend biaxially oriented film.