CN111183175A

CN111183175A - Polymer film and loudspeaker diaphragm comprising the same

Info

Publication number: CN111183175A
Application number: CN201880064133.1A
Authority: CN
Inventors: 安德鲁·艾里瑞; 柯林·瑞默
Original assignee: Victrex Manufacturing Ltd
Current assignee: Victrex Manufacturing Ltd
Priority date: 2017-10-12
Filing date: 2018-10-11
Publication date: 2020-05-19
Also published as: WO2019073242A1; GB201716764D0; GB2567468A; EP3694911A1

Abstract

A polymer film is disclosed. The membrane comprises a polymeric material having repeat units of the formula-O-Ph-CO-Ph- (I) and repeat units of the formula-O-Ph-O-Ph-CO-Ph- (II), wherein Ph represents a phenylene moiety, and wherein the shear viscosity SV of the polymeric material, as measured by the standard method defined in ISO11443:2014, is in the range of from about 400pa.s to about 600pa.s at 340 ℃. A loudspeaker diaphragm and a method of manufacturing a loudspeaker diaphragm are also disclosed.

Description

Polymer film and loudspeaker diaphragm comprising the same

Technical Field

A polymer film is disclosed. In particular, a polymer film suitable for micro-speaker diaphragms used in portable devices is disclosed.

Background

As personal devices such as smartphones and smartwatches become smaller, the demand for miniaturization of the acoustic components that make up the devices such as speakers and receivers has proliferated. However, the acoustic performance of small loudspeakers and receivers can also be affected. The most affected by the miniaturization of speakers and receivers is the low frequency acoustic performance, e.g., low pitch.

Polymeric films are often used in such devices. Polyaryletherketones (PAEKs) generally have excellent mechanical properties and are used in portable devices. PAEKs are the material of choice for many acoustic devices because of their excellent mechanical properties. However, even if high performance polymers (e.g., PAEKs) are used to make polymer membranes for acoustic assemblies, it is still a challenge to achieve the performance requirements needed to further miniaturize the acoustic assemblies.

There is a need for a polymer membrane suitable for use as a micro-speaker diaphragm that exhibits improved low frequency acoustic performance while still providing good mechanical properties to provide improved fatigue performance.

Disclosure of Invention

In a first aspect, a polymeric film is disclosed, the film comprising a polymeric material having a repeat unit of the formula

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

Wherein Ph represents a phenylene moiety, and wherein the shear viscosity SV of the polymeric material, measured by the standard method defined in ISO11443:2014, is in the range of about 400pa.s to about 600pa.s at 340 ℃.

It has surprisingly been found that the above-described polymer films are particularly suitable for many applications, including but not limited to acoustic devices, layered structures and optical devices.

Preferably, the SV of the polymeric material is in the range between 450pa.s or more and 550pa.s or less at 340 ℃. More preferably, the SV is in the range between 480Pa.s and 520Pa.s at 340 ℃.

In particular, one benefit of the polymeric material is that it exhibits improved optical properties. For example, the polymer films of the present invention were determined to have significantly reduced% haze compared to PEEK polymer films of the same thickness. In some examples, a reduction in measured haze% of up to 6% is measured when compared to other polymer films having similar thicknesses.

Preferably, a polymer film having a nominal thickness of 6 μm has a transmission haze of less than 5% as measured by ASTM D1003-2013. More preferably, the polymeric film has a transmission haze of less than 2%, or less than 1%. Most preferably, the polymeric film has a transmission haze of 0.5% or less.

Optionally, the polymer film is amorphous. It has surprisingly been found that when configured as a single loudspeaker diaphragm (spaker diaphragm), the amorphous polymer film exhibits a lower resonance frequency F than other comparative films configured as single loudspeaker diaphragms₀。

Alternatively, the polymer film is crystalline.

Preferably, the polymer film has a thickness of 3 μm to 100 μm, more preferably a thickness of 3 μm to 25 μm, or 3 μm to 12 μm or less, or 3 μm to 9 μm or less, or 3 μm to less than 5 μm.

Alternatively, the polymer film has a thickness of 50 μm to 70 μm, or 55 μm or more to 65 μm or less.

In a second aspect, a loudspeaker diaphragm is disclosed, comprising:

at least one film comprising a polymeric material having a repeating unit of the formula

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

It has surprisingly been found that in use the loudspeaker diaphragm exhibits a significant improvement in sound production, in particular at low frequencies, resulting in an overall improved loudspeaker performance, especially at lower frequencies compared to known loudspeaker diaphragms.

Preferably, at least one of the films has a thickness of 3 μm to 25 μm, more preferably a thickness of 3 μm to 12 μm or less, or most preferably 3 μm to 9 μm or less, or 3 μm to less than 5 μm.

Preferably, the loudspeaker diaphragm has a measured lowest resonance frequency F of up to 50Hz, compared to a comparative loudspeaker diaphragm₀There is a reduction in. It has surprisingly been found that the loudspeaker diaphragm of the invention exhibits a lower resonance frequency F compared to loudspeaker diaphragms made from PEEK₀。

Preferably, at least one of the films is amorphous. It was surprisingly found that the film in the amorphous state exhibited an even lower resonance frequency than the film in the amorphous state.

In one example, the loudspeaker diaphragm is improved in the lowest achievable resonance frequency up to 50Hz compared to other loudspeaker diaphragms.

Alternatively, the at least one thin film is crystalline. In this example, the loudspeaker diaphragm may be improved in the lowest attainable resonance frequency up to 20Hz compared to other loudspeaker diaphragms.

Optionally, the membrane is a layered structure comprising a plurality of material layers. The membrane may comprise layers of different polymeric materials, or layers of adhesive or backing materials.

In another aspect, there is provided a method of manufacturing a loudspeaker diaphragm, the method comprising the steps of:

(i) extruding a film comprising a polymeric material having a repeating unit of the formula

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

Wherein Ph represents a phenylene moiety;

wherein the relative molar ratio I to II of the recurring units I and II is 65:35 to 95: 5;

(ii) thermoforming the film into a film sheet.

The method may further comprise the step of laminating the film after step (i). The lamination process may include adding a damping layer to the film.

The following features apply to the polymeric material:

preferably, the relative molar ratio of recurring units I and II is from 65:35 to 95:5, for example 75: 25.

Preferably, in the polymeric material, the following relationship applies:

log₁₀(X％)>1.50-0.26MV；

wherein X% refers to the crystallinity measured as described in example 31 of WO2014207458A1 incorporated herein, and wherein MV refers to the melt viscosity using a circular cross-section tungsten carbide die of 0.5mm (capillary diameter) X3.175 mm (capillary length) also as described in WO2014207458A1, using a capillary rheometer at 1000s at 340 deg.C^-1Measured by shear rate manipulation. MV measurements were taken 5 minutes after the polymer was completely melted, which was 5 minutes after the polymer was loaded into the rheometer barrel.

The phenylene moieties (Ph) in each repeat unit can independently have 1, 4-para bonds or 1, 3-meta bonds to the atoms to which they are bonded. In the case where the phenylene moiety includes a1, 3-bond, the moiety will be in the amorphous phase of the polymer. The crystalline phase will comprise phenylene moieties having 1, 4-linkages. In many applications, the polymeric material is preferably highly crystalline, and therefore, preferably includes a high level of phenylene moieties having 1, 4-linkages.

In a preferred embodiment, at least 95%, preferably at least 99% of the number of phenylene moieties (Ph) in the repeat unit of formula I have 1, 4-linkages to the moiety to which they are bonded. It is particularly preferred that each phenylene moiety in the repeat unit of formula I has a1, 4-bond to the moiety to which it is bonded.

In a preferred embodiment, at least 95%, preferably at least 99% of the number of phenylene moieties (Ph) in the repeat unit of formula II have 1, 4-linkages to the moiety to which they are bonded. It is particularly preferred that each phenylene moiety in the repeat unit of formula II has a1, 4-bond to the moiety to which it is bonded.

Preferably, the phenylene moieties in the repeat units of formula I are unsubstituted. Preferably, the phenylene moieties in the repeating units of formula II are unsubstituted.

The repeat unit of formula I suitably has the structure

The repeating unit of formula II suitably has the structure

Preferred polymeric materials according to the present invention have a crystallinity greater than that contemplated by the prior art. Preferably, log₁₀(X%) is more than 1.50-0.23 MV. More preferably, log₁₀(X％)＞1.50～0.28MV+0.06MV²。

The polymeric material may comprise at least 68 mol%, preferably at least 71 mol% of recurring units of formula I. Particularly advantageous polymeric materials may comprise at least 72 mol%, or especially at least 74 mol%, of recurring units of the formula I. The polymeric material may comprise less than 90 mol%, suitably 82 mol% or less of repeat units of formula I. The polymeric material may comprise 68 to 82 mol%, preferably 70 to 80 mol%, more preferably 72 to 77 mol% of the repeat units of formula I.

The polymeric material may comprise at least 10 mol%, preferably at least 18 mol%, of recurring units of formula II. The polymeric material may comprise less than 32 mol%, preferably less than 29 mol% of repeat units of formula II. Particularly advantageous polymeric materials may comprise less than 28 mol%, or less than 26 mol% of recurring units of formula II. The polymeric material may comprise from 18 to 32 mol%, preferably from 20 to 30 mol%, more preferably from 23 to 28 mol% of units of formula II.

The sum of the mol% of the units of formulae I and II in the polymeric material is suitably at least 95 mol%, preferably at least 98 mol%, more preferably at least 99 mol%, especially about 100 mol%.

The ratio defined as the mol% of the unit of formula I divided by the mol% of the unit of formula II may be in the range of 1.8 to 5.6, suitably in the range of 2.3 to 4, and preferably in the range of 2.6 to 3.3.

The Tm of the polymeric material (suitably measured as described herein) may be less than 330 ℃, suitably less than 320 ℃, preferably less than 310 ℃. In some embodiments, the Tm may be less than 306 ℃. The Tm can be greater than 280 ℃, or greater than 290 ℃, 295 ℃, or 300 ℃. The Tm is preferably in the range of 300 ℃ to 310 ℃.

The Tg of the polymeric material (suitably measured as described herein) may be greater than 130 ℃, preferably greater than 135 ℃, more preferably greater than 140 ℃. The Tg may be less than 175 deg.C, less than 165 deg.C, less than 160 deg.C or less than 155 deg.C. The Tg is preferably in the range from 145 ℃ to 155 ℃.

The difference between Tm and Tg (Tm-Tg) may be at least 130 ℃, preferably at least 140 ℃, more preferably at least 150 ℃. The difference may be less than 170 ℃ or less than 165 ℃. In a preferred embodiment, the difference is in the range of 145-165 ℃.

In a preferred embodiment, the polymeric material has a Tg in the range of 145 ℃ to 155 ℃, a Tm in the range of 300 ℃ to 310 ℃, and a difference between Tm and Tg in the range of 145 ℃ to 165 ℃.

The polymeric material may have a crystallinity of about 10 to 20% as measured as described in example 31 of WO2014207458a1 incorporated herein.

The polymeric material suitably has at least 0.10kNsm^-2Preferably has a Melt Viscosity (MV) of at least 0.15kNsm^-2More preferably at least 0.20kNsm^-2In particular at least 0.25kNsm^-2The MV of (1). Using a tungsten carbide mold of 0.5mm by 3.175mm, using a mold at 340 ℃ for 1000s^-1Suitably MV is measured with a capillary rheometer operating at a shear rate. The polymeric material may have less than 1.8kNsm^-2Suitably less than 1.2kNsm^-2。

The polymeric material may have a tensile strength of at least 40MPa, preferably at least 60MPa, more preferably at least 80MPa, measured according to ISO 527. The tensile strength is preferably in the range of 80 to 110MPa, more preferably in the range of 80 to 100 MPa.

The polymeric material may have a flexural strength of at least 130MPa measured according to ISO 178. The bending strength is preferably in the range of 135 to 180MPa, more preferably in the range of 140 to 150 MPa.

The polymeric material may have a flexural modulus of at least 2GPa, preferably at least 3GPa, measured according to ISO 178. The flexural modulus is preferably in the range of 3.0 to 4.5GPa, more preferably in the range of 3.0 to 4.0 GPa.

The polymeric material may be in the form of pellets or granules, wherein the pellets or granules comprise at least 95 wt%, preferably at least 99 wt%, especially about 100 wt% of the polymeric material. The pellets or granules may have a maximum dimension of less than 10mm, preferably less than 7.5mm, more preferably less than 5.0 mm.

In the context of the present invention, the glass transition temperature (Tg), the cold crystallization temperature (Tn), the melting temperature (Tm) and the heat of nucleation (Δ Hn) and heat of fusion (Δ Hm) are determined using the DSC method described below.

The dried polymer samples were compression molded into amorphous films by heating 7g of the polymer in a 400 ℃ mold under a pressure of 50bar for 2 minutes and then quenching in cold water to produce films having dimensions of 120X 120mm and a thickness of about 0.20 mm. 8mg plus or minus 3mg samples of each film were scanned by DSC as follows:

step 1 an initial thermal cycle was performed and recorded by heating the sample from 30 ℃ to 400 ℃ at 20 ℃/min.

Step 2 was held for 5 minutes.

Step 3 was cooled to 30 ℃ at 20 ℃/min and held for 5 minutes.

Step 4 reheat from 30 ℃ to 400 ℃ at 20 ℃/min and record Tg, Tn, Tm, Δ Hn and AHm.

From the DSC trace obtained from the scan in step 4, the onset of Tg can be obtained, which is the intersection of a line drawn along the pre-transition baseline and a line drawn along the maximum slope obtained during the transition. Tn is the temperature at which the main peak of the cold crystallization exotherm reaches a maximum. The Tm is the temperature at which the main peak of the melting endotherm reaches a maximum.

The heat of fusion for nucleation (Δ Hn) and the heat of fusion (Δ Hm) are obtained by connecting two points where the cold crystallization and melting endotherms deviate from a relatively flat baseline. The integrated area under the endotherm as a function of time yields the enthalpy of the particular transition (mJ), and the mass normalized heat of fusion is calculated by dividing the enthalpy by the mass of the sample (J/g).

Polymeric materials

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

Wherein Ph represents a phenylene moiety, can be produced using the following process, and is described in WO2014207458a1 and incorporated herein, comprising polycondensing a mixture of at least one dihydroxybenzene compound and at least one dihydroxybiphenyl compound with at least one dihalobenzophenone in a molar ratio of 65:35 to 95:5 in the presence of sodium carbonate and potassium carbonate, wherein:

(i) the mole% of the potassium carbonate is at least 2.5 and less than 5, and/or

(ii) The following relationship (referred to as the "D50/mol%) applies:

the mole% of potassium carbonate is suitably defined as:

d50 of sodium carbonate can be measured as described in example 29 of WO2014207458a1 incorporated herein.

The mole% of potassium carbonate is suitably defined as:

in option (i), the mole% of the potassium carbonate may be at least 3 mole%, preferably at least 3.5 mole%, more preferably at least 3.9 mole%. The mole% of the potassium carbonate may be in the range of 3.5 to 4.9 mole%.

Suitably, the total moles of carbonate used in the process (i.e. the total number of moles of carbonate used in the process divided by the total number of moles of hydroxyl monomer(s) used, expressed as a percentage) is at least 100%.

The total mole% of carbonate may be greater than 100 mole%. It may be less than 105 mole%.

The mole% of sodium carbonate used in the process may be at least 90 mole%, preferably at least 92 mole%, more preferably at least 95 mole%.

The sum of the mole% of sodium carbonate and potassium carbonate used in the process (again in relation to the moles of the hydroxyl monomer (s)) is preferably at least 100 mole%, and more preferably more than 100 mole%. It may be in the range of 100-105 mole%.

Mole% of carbonates other than sodium carbonate and potassium carbonate used in the process (the term is intended to cover Carbonates (CO)₃ ^2-) And bicarbonate (HCO)₃ ^-) Preferably less than 5 mole%, more preferably less than 1 mole% (again with respect to the moles of hydroxyl monomer (s)).

Preferably, the most suitable carbonates for use in the process are sodium carbonate and potassium carbonate.

Under option (ii), the D50/mol% relationship is preferably less than 44, more preferably less than 42, in particular less than 40. The relationship may be less than 30 or 26. D50 was suitably measured as described in example 29 of WO2014207458a1 incorporated herein.

Preferably, both the relationships described in options (i) and (ii) apply.

The potassium carbonate selected for use in the process is preferably capable of passing through a 500 μm mesh screen.

The sodium carbonate suitably has a D50 of less than 140 μm, preferably less than 125 μm, more preferably less than 110 μm. D50 may be at least 50 μm.

The following features are generally applicable to the present invention:

the polymeric material may form part of a composition, which may comprise the polymeric material and fillers (fillers). The filler may comprise a fibrous filler or a non-fibrous filler. The filler may include both fibrous fillers and non-fibrous materials. The fibrous filler may be continuous or discontinuous.

The fibrous filler may be selected from inorganic fibrous materials, non-melting and high melting point organic fibrous materials, such as aramid fibers, and carbon fibers.

The fibrous filler may be selected from glass fibers, carbon fibers, asbestos fibers, silica fibers, alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, fluorocarbon resin fibers and potassium titanate fibers. Preferred fibrous fillers are glass fibers and carbon fibers.

The fibrous filler may comprise nanofibers.

The non-fibrous filler may be selected from mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate, fluorocarbon resin, graphite, carbon powder, nanotubes and barium sulfate. The non-fibrous filler may be introduced in the form of a powder or a flake-like particle.

The composition may define a composite material which may be prepared as described in "impregnation technique of thermoplastic matrix composites". Polymer and Polymer composites by Miller and A G Gibson4(7) 459-481(1996), EP102158 and EP102159, the contents of which are incorporated herein by reference. Preferably, in the method, the mixing of the polymeric material and the filler is carried out at an elevated temperature, suitably at a temperature at or above the melting temperature of the polymeric material. Thus, suitably, the polymeric material and the filler are mixed while the polymeric material is molten. The elevated temperature is suitably below the decomposition temperature of the polymeric material. The above-mentionedThe elevated temperature is preferably at or above the main peak of the melting endotherm (Tm) of the polymeric material. The elevated temperature is preferably at least 300 ℃. Advantageously, the molten polymeric material can readily wet the filler and/or penetrate into a consolidated filler, such as a fibrous mat or woven fabric, thus producing a composite comprising the polymeric material and the filler substantially uniformly dispersed throughout the polymeric material.

The composite material may be prepared in a substantially continuous process. In this case, the polymeric material and the filler may be continuously supplied to the location where they are mixed and heated. An example of such a continuous process is extrusion. Another example, where it may be particularly relevant for the filler to comprise a fibrous filler, involves moving a continuous filamentous substance through a melt or aqueous dispersion containing the polymeric material. The continuous filamentous material may comprise a continuous length of fibrous filler, or more preferably, a plurality of continuous filaments that have been consolidated, at least to some extent. The continuous fiber material may comprise tow, roving, braid, woven or nonwoven fabric. The filaments making up the fibrous mass may be arranged substantially uniformly or randomly within the mass. The composite material may be prepared as described in PCT/GB2003/001872, US6372294 or EP 1215022.

Alternatively, the composite material may be prepared in a discontinuous process. In this case, a predetermined amount of the polymeric material and a predetermined amount of the filler may be selected and contacted and the composite material prepared by melting the polymeric material and mixing the polymeric material and the filler to form a substantially homogeneous composite material.

The composite material may be formed into particulate form, for example into pellets or granules. The pellets or granules may have a largest dimension of less than 10mm, preferably less than 7.5mm, more preferably less than 5.0 mm.

Preferably, the filler comprises one or more fillers selected from glass fibers, carbon black and fluorocarbon resins. More preferably, the filler comprises glass fibers or carbon fibers.

In the following discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limits of a parameter's permissible range, plus an indication that one of the stated values is more highly preferred than the other, is to be interpreted as an implied statement that each intermediate value of the parameter, lying between the more preferred and less preferred of the stated alternative values, is itself preferred to the less preferred value, and is also preferred to each value lying between the less preferred value and the intermediate value.

Throughout the specification, the term "comprising" means including the specified components, but not excluding the presence of other components. The term "consisting essentially of … …" means to include the specified components, but not to include other components except for materials present as impurities, materials inevitably present due to processes for providing the components, and components added for purposes other than achieving the technical effects of the present invention. Generally, when referring to a composition, a composition consisting essentially of one set of components will comprise less than 5 weight percent, typically less than 3 weight percent, more typically less than 1 weight percent of non-specified components.

The term "consisting of" means including the specified components but not including other components.

References herein such as "in the range of x to y" are meant to include such interpretations as "from x to y" and thus include both x and y values.

The use of the term "comprising" may also be considered to include the meaning "consisting essentially of", and may also be considered to include the meaning "consisting of", where appropriate, depending on the context.

Drawings

Embodiments of the invention will be further described hereinafter with reference to the accompanying drawings, in which:

FIG. 1 illustrates a typical film extrusion process; and

fig. 2 illustrates the measurement of the resonant frequency of many receivers.

Detailed Description

The polymer film is formed using a typical sheet/film extrusion process in which polymer particles are added to a hopper 2 and melted to form a polymer melt. The polymer melt is then directed under pressure through an extruder 4 to a die 6. The shape of the die 6 controls the width and thickness of the film 10. The film is then cooled under tension by a plurality of rollers or calenders 12. The roll or calender 12 may be arranged to stretch the film to further control the dimensions of the film, such as the thickness of the film. The film is then wound onto a core.

Example 1 measurement of shear viscosity

Using a circular cross-section tungsten carbide die of 0.5mm (capillary diameter) × 3.175mm (capillary length), using a capillary rheometer at 340 ℃ for 1000s^-1Shear viscosity SV is measured according to the standard method defined in ISO11443: 2014. The SV range of the selected polymeric material is from about 400Pa.s to about 600Pa.s at 340 deg.C.

Example 1 crystallinity measurement of thin films

The crystallinity of a polymer film can be assessed by several methods, for example by density, by infrared spectroscopy, by X-ray diffraction or by Differential Scanning Calorimetry (DSC). The DSC method has been used to evaluate the degree of crystallinity formed in a polymer using a DSC Q100, Q2000 or Q2500 instrument from TA Instruments under a nitrogen flow rate of 40 ml/min.

The glass transition temperature (Tg), the cold crystallization temperature (Tn), the melting temperature (Tm) and the heat of fusion of nucleation (Δ Hn) and melting heat of fusion (Δ Hm) of the polymer film were determined using the following DSC method.

Samples of each polymer film were prepared by cutting small pieces of a suitable standard aluminum DSC pan until an amount of between 5-10mg was reached. The sample was then scanned by DSC as follows:

1: equilibrating at 40.00 deg.C

2: isothermal for 2.00 min

3: ramping to 400.00 deg.C at 20.00 deg.C/min

5: equilibrating at 40.00 deg.C

From the DSC curve scanned in step 4, the onset of Tg can be obtained, which is the intersection of a line drawn along the pre-transition baseline and a line drawn along the maximum slope obtained during the transition. The determined Tg was about 150 ℃. Tn corresponds to the temperature at which the main peak of the cold crystallization exotherm reaches a maximum. The Tm corresponds to the temperature at which the main peak of the melting endotherm reaches a maximum. Tc corresponds to the temperature at which the main peak of crystallization from the melt exotherm reaches a maximum.

The heat of fusion (Δ H (J/g)) can be obtained by connecting two points that deviate the melting endotherm from a relatively straight baseline. The integrated area under the endotherm as a function of time yields the enthalpy of melting transition (mJ): by dividing the enthalpy by the sample mass (J/g), the mass normalized heat of fusion can be calculated. The degree of crystallinity (%) was determined by dividing the heat of fusion of the sample by the heat of fusion of the fully crystalline polymer, assuming a heat of fusion of 130J/g for PEEK: PEDEK.

Using the DSC method described above, the amorphous polymer film of the present invention has a crystallinity of about 5% which is less than that found for the comparative PEEK film having a crystallinity of about 10%. The crystalline polymer film of the present invention was found to have a crystallinity of about 20%, whereas the comparative PEEK film had a crystallinity of about 30%. These values are, however, based on the assumption that the melting enthalpy of PEDEK is the same as the melting enthalpy of PEEK according to the invention.

Example 2 measurement of haze

The transmission haze of the films according to the invention was determined using the standard test method ASTM D1003. Transmission haze determines the transmission properties of the transparent film. Light transmission through a film can be affected by irregularities (irregularities) in the film. The singularities may cause light to scatter in different directions. When light is scattered by small singularities, this scattering behavior is called wide angle scattering, which causes haze due to loss of transmission contrast. Transmission haze is therefore the amount of light that undergoes wide angle scattering at angles greater than 2.5 ° from normal.

Polymer film samples were prepared using 6 μm and 8 μm film sheets and measured on a 57D Hazemeter (haze Meter). Table 1 shows the% haze and% transmission properties. Surprisingly, it was found that the PEEK-PEDEK films according to the invention have a significantly lower haze than PEEK films prepared in the same way.

Table 1: haze and Transmission measured according to ASTM D1003

One advantage of the polymer films of the present invention is in electronic displays. The combination of low haze and good mechanical properties makes this particular film suitable for use in flexible electronic displays.

Example 3 comparison of lowest resonance frequencies

The polymer film of the present invention is thermoformed into a single speaker diaphragm and used to construct a simple receiver to measure the resonant frequency of the speaker diaphragm. A comparative film comprising PEEK was also thermoformed into a speaker diaphragm and constructed as a simple receiver to provide comparative data between the speaker diaphragm of the present invention and a speaker diaphragm made of PEEK. The receiver is identical except for the film used to form the membrane. The receivers are low power speakers and are used for comparative testing because they are easy to test. To manufacture the receiver, the film is first thermoformed into a membrane and then configured to form the receiver.

Thermoforming is a manufacturing process in which a film is heated to a pliable forming temperature, then formed into a particular shape in a mold, and trimmed to produce a usable film sheet. Typically, the membrane is placed in a tool comprising male and female portions and held under pressure. A temperature is applied to the tool to shape the film into the shape of the tool. The temperature of the tool is set at about 130 ℃ to about 150 ℃ to form the membrane. For crystalline films, the tool temperature will rise to up to about 185 ℃. Samples 2, 3 and 5 correspond to crystalline film sheets. The film had a nominal thickness of 6 μm. Once configured as a receiver, an impedance test is performed to determine the lowest resonant frequency of the receiver.

Sample (I)	Mean resonance frequency (Hz)
		1-PEEK 6um thin film-amorphous	426
2-PEEK 6um film-crystal	454
		Thin film-crystal of 3-PEEK 6um	410
4-PEEK-PEDEK 6um thin film-amorphous	366
		5-PEEK-PEDEK 6um film-crystals	390

TABLE 2 measurement of resonant frequency of loudspeaker diaphragm (speak)

FIG. 2 and Table 2 show the results of impedance measurements to determine the resonant frequency F of receivers produced using different films₀. Samples 1 and 4 correspond to amorphous film samples and samples 2 and 5 correspond to crystalline film samples that were crystallized using a thermoforming process. Sample 3 corresponds to a crystalline film that is crystalline prior to thermoforming. Surprisingly, the receiver with the membrane according to the invention exhibits lower resonance frequencies in use compared to a similar receiver made from PEEK film.

Even more surprising is that receivers made using amorphous films exhibit the lowest measurable F in use₀. It has been found that the use of the loudspeaker membrane of the invention results in a significant improvement of the performance of the micro-loudspeaker in the lower frequency range.

Without being bound by theory, it is believed that the polymer film of the present invention provides a speaker diaphragm (thermoformed) having a lower modulus than other polymeric materials thermoformed speaker diaphragms. The modulus of the polymer film according to the invention is similar to that of the extruded PEEK film, but when thermoformed into a speaker diaphragm and configured as a simple receiver, it shows that the modulus of the polymer film of the invention is reduced. Is thought to be due to F₀Is related to the modulus of the film, and therefore F can be considered₀The reduction in (c) is associated with lower modulus membranes.

Figure 2 shows that a receiver formed using a diaphragm of the polymer film of the present invention provides a reduction of up to 50Hz at the lowest acoustic frequencies measured.

The Tg of the polymeric material is also suitably high, allowing the loudspeaker diaphragm of the present invention to withstand higher temperatures without failure.

Another benefit of the film is that it can be used in laminates. Under certain processing conditions, the film provides excellent adhesion to other material layers. The crystalline film is particularly useful in laminates.

It should be understood that optional features applicable to one aspect of the invention may be used in any combination and in any number. Moreover, they may also be used with any other aspect of the invention in any combination and in any number. This includes, but is not limited to, a dependent claim from any claim which is used as a dependent claim from any other claim in the claims of this application.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A polymeric membrane comprising a polymeric material having a repeat unit of the formula

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

2. The polymer film of claim 1, wherein the SV is in a range between 450pa.s or more and 550pa.s or less at 340 ℃.

3. The polymer film according to claim 1 or 2, wherein the SV is in the range between 480 Pa-s and 520 Pa-s at 340 ℃.

4. The polymer film of any one of the preceding claims, wherein the polymer film has a nominal thickness of 6 μ ι η and a transmission haze of less than 5% as measured by ASTM D1003-2013.

5. The polymeric film of claim 4, wherein the polymeric film has a transmission haze of less than 2%, or less than 1%, or the polymeric film has a transmission haze of 0.5% or less.

6. The polymer film of any one of the preceding claims, wherein the polymer film is amorphous.

7. The polymer film of any one of claims 1 to 5, wherein the polymer film is crystalline.

8. The polymer film according to any one of the preceding claims, wherein the polymer film has a thickness of from 3 to 100 μ ι η, or has a thickness of from 3 to 25 μ ι η, or has a thickness of from 3 to 12 μ ι η or less, or has a thickness of from 3 to 9 μ ι η or less, or has a thickness of from 3 to less than 5 μ ι η.

9. The polymer film according to any one of claims 1 to 7, wherein the polymer film has a thickness of from 50 μm to 70 μm, or a thickness of 55 μm or more and 65 μm or less.

10. A loudspeaker diaphragm comprising:

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

11. The loudspeaker diaphragm of claim 10, wherein the SV of the polymeric material is in a range between 450pa.s or more and 550pa.s or less at 340 ℃.

12. A loudspeaker diaphragm according to claim 10 or 11, wherein the SV of the polymeric material is in the range between 480 Pa-s and 520 Pa-s at 340 ℃.

13. A loudspeaker diaphragm according to any one of claims 10 to 12, wherein the at least one film has a thickness of from 3 μm to 25 μm; or

The at least one thin film has a thickness of 3 to 12 μm or less; or

The at least one thin film has a thickness of 3 μm to 9 μm or less; or

The at least one thin film has a thickness of 3 μm to less than 5 μm.

14. The loudspeaker diaphragm of any one of claims 10 to 13, wherein the at least one thin film is amorphous.

15. A loudspeaker diaphragm according to any one of claims 10 to 14, wherein the loudspeaker diaphragm has an improvement over the lowest achievable resonance frequency up to 50Hz compared to the other loudspeaker diaphragms.

16. A loudspeaker diaphragm according to any one of claims 10 to 13, wherein the at least one thin film is crystalline.

17. The speaker diaphragm of claim 16, wherein the speaker diaphragm has an improvement in the lowest resonance frequency achievable up to 20Hz compared to other speaker diaphragms.

18. A loudspeaker diaphragm according to any one of claims 10 to 17, wherein the diaphragm is a laminated structure comprising a plurality of layers of material.

19. A method of manufacturing a loudspeaker diaphragm, the method comprising the steps of:

-O-Ph-O-Ph-CO-Ph- I

And a repeating unit of the formula

-O-Ph-Ph-O-Ph-CO-Ph- II

Wherein Ph represents a phenylene moiety, and wherein the shear viscosity SV of the polymeric material, measured by the standard method defined in ISO11443:2014, is in the range of about 400pa.s to about 600pa.s at 340 ℃;

(ii) thermoforming the film into a film sheet.

20. The method of claim 19, wherein the method further comprises the step of laminating the film after step (i).

21. The method of claim 20, wherein the lamination process includes adding a damping layer to the film.