Patent Application
20250116878
Camera modules (or components) are often employed in mobile phones, laptop computers, digital cameras, digital video cameras, etc. Generally, the camera module includes a lens unit and an image sensor for converting an image of an object into an electrical signal. The lens unit may be disposed in a housing unit and include a lens barrel having one or more lenses disposed therein. In addition, the camera module may include an actuator unit for optical image stabilization (OIS) to reduce resolution loss, or blurring, caused by hand-shake. The actuator unit functions by moving the lens unit to a target position after receiving a certain signal. To help ensure proper alignment of the lens unit during movement, many actuator units include ball bearings to help guide the lens unit in the desired direction. Conventionally, these ball bearings are formed from a ceramic material that is sufficiently strong to withstanding the forces exerted during use. While strong, the ball bearings can nevertheless cause dents and scratches to form on surfaces of the camera module, which create noise and impact performance. To help minimize these issues, camera modules often employ an elastic “damper” that acts as a shock absorbing agent to minimize damage to the surfaces of the camera module. Although elastic materials, such as natural rubber, can be good shock absorbing materials, it can nevertheless be difficult to apply such materials within the intricate spaces of a small camera module due to their inability to be readily molded. As such, a need currently exists for a damper that can be flexible and yet still readily molded into a part with a small dimensional tolerance for a camera module.
In accordance with one embodiment of the present invention, a camera module is disclosed that comprises a lens unit mounted in a housing unit, an actuator unit configured to allow relative movement of the lens unit with respect to the housing unit, and a damper disposed between the housing unit and the lens unit. The damper comprises a polymer composition that includes a liquid crystalline polymer and that exhibits a Shore D hardness of about 75 or less as determined in accordance with ISO 868:2003.
Other features and aspects of the present invention are set forth in greater detail below.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention.
Generally speaking, the present invention is directed to a damper for use in a camera module that contains a lens unit mounted in a housing unit and an actuator unit configured to allow relative movement of the lens unit with respect to the housing unit. The damper is disposed between the housing unit and the lens unit so that it is capable of minimizing surface damage and/or noise due to contact of portions of the camera module with each other, such as the housing unit, lens unit, ball members, etc. The damper contains contains a polymer matrix including a liquid crystalline polymer. By selectively controlling the particular nature of the composition, the present inventor has discovered that the resulting composition can exhibit a high degree of flexibility and/or shock absorbing qualities, but still be readily molded or formed into a damper having a small dimensional tolerance.
The polymer composition may, for example, exhibit a tensile modulus of about 5,500 MPa or less, in some embodiments from about 500 MPa to about 5,200 MPa, in some embodiments from about 1,000 MPa to about 5,000 MPa, and in some embodiments, from about 1,500 MPa to about 4,500 MPa, as determined in accordance with ISO 527:2019 at 23° C. The tensile break strain (or elongation) may also be about 1% or more, in some embodiments from about 2% to about 15%, in some embodiments from about 3% to about 12%, and in some embodiments, from about 4% to about 10%, as determined in accordance with ISO 527:2019 at 23° C. Likewise, the composition may exhibit a flexural modulus of about 6,000 MPa or less, in some embodiments from about 500 MPa to about 5,800 MPa, in some embodiments from about 1,000 MPa to about 5,500 MPa, and in some embodiments, from about 2,000 MPa to about 5,000 MPa, as determined in accordance with ISO 178:2019 at 23° C. The polymer composition may also exhibit a Rockwell surface hardness of about 90 or less, in some embodiments about 75 or less, in some embodiments about 40 or less, in some embodiments about 30 or less, in some embodiments about 25 or less, and in some embodiments, from about 5 to about 20, as determined in accordance with ASTM D785-08 (Scale M). The ability to achieve such a tensile modulus, tensile break strain, flexural modulus, and/or Rockwell hardness may, among other things, help improve the softness and the flexibility of the composition so that it better serve as a shock absorbing material for use in applications requiring a small dimensional tolerance.
Of course, the polymer composition may still retain a high degree of strength. For example, the tensile strength of the composition may range from about 30 to about 250 MPa, in some embodiments from about 40 to about 230 MPa, and in some embodiments, from about 60 to about 200 MPa as determined in accordance with ISO 527:2019 at 23° C. Likewise, the polymer composition may exhibit a flexural strength of from about 30 to about 250 MPa, in some embodiments from about 40 to about 230 MPa, and in some embodiments, from about 60 to about 200 MPa, as determined in accordance with ISO 178:2019 at 23° C. The composition may also exhibit a high degree of impact strength, such as exhibited by a high Charpy notched impact strength of about 10 kJ/m2 or more, in some embodiments about 20 kJ/m2 or more, in some embodiments from about 40 to about 120 kJ/m2, and in some embodiments, from about 50 to about 100 kJ/m2, and/or a Charpy unnotched impact strength of about 5 kJ/m2 or more, in some embodiments from about 10 to about 120 kJ/m2, and in some embodiments, from about 15 to about 100 kJ/m2 as measured at a temperature of 23° C. according to ISO 179-1:2010.
While possessing the properties of good softness, flexibility and strength, the polymer composition is also highly flowable, which can facilitate the ability of the composition to be used in dampers having a very small thickness and/or overall size. The thickness of the damper may, for example, be from 0.01 to about 5 millimeters, in some embodiments from about 0.05 to about 2.5 millimeters, and in some embodiments, from about 0.1 to about 1 millimeter. The polymer composition may exhibit a melt viscosity of about 300 Pa-s or less, in some embodiments about 250 Pa-s or less, in some embodiments from about 5 to about 200 Pa-s, in some embodiments from about 10 to about 150 Pa-s, and in some embodiments, from about 20 to about 100 Pa-s, as determined at a shear rate of 1,000 s−1 in accordance with ISO 11443:2021 at a temperature that is 15° C. higher than the melting temperature of the composition. The heat resistance of the polymer composition may also be good. For example, the melting temperature of the composition and/or liquid crystalline polymer(s) used in the polymer matrix may be about 200° C. or more, in some embodiments about from about 210° C. to about 360° C., and in some embodiments, from about 260° C. to about 340° C. Further, the deflection temperature under load (DTUL) may be about 70° C. or more, in some embodiments about 80° C. or more, in some embodiments about 90° C. or more, in some embodiments about 100° C. or more, and in some embodiments, from about 110° C. to about 160° C., as measured according to ASTM D648-18 (technically equivalent to ISO 75-2:2013) at a specified load of 1.8 MPa.
Various embodiments of the present invention will now be described in more detail.
The polymer matrix typically constitutes from about 30 wt. % to about 90 wt. %, in some embodiments from about 35 wt. % to about 85 wt. %, in some embodiments from about 40 wt. % to about 80 wt. %, and in some embodiments, from about 45 wt. % to about 75 wt. % of the polymer composition. As indicated above, the polymer matrix generally contains a liquid crystalline polymer. Liquid crystalline polymers are generally classified as “thermotropic” to the extent that they can possess a rod-like structure and exhibit a crystalline behavior in their molten state (e.g., thermotropic nematic state). Such polymers may be formed from one or more types of repeating units as is known in the art. A liquid crystalline polymer may, for example, contain one or more aromatic ester repeating units generally represented by the following Formula (I):
wherein,
ring B is a substituted or unsubstituted 6-membered aryl group (e.g., 1,4-phenylene or 1,3-phenylene), a substituted or unsubstituted 6-membered aryl group fused to a substituted or unsubstituted 5- or 6-membered aryl group (e.g., 2,6-naphthalene), or a substituted or unsubstituted 6-membered aryl group linked to a substituted or unsubstituted 5- or 6-membered aryl group (e.g., 4,4-biphenylene); and
Y1 and Y2 are independently O, C(O), NH, C(O)HN, or NHC(O).
Typically, at least one of Y1 and Y2 are C(O). Examples of such aromatic ester repeating units may include, for instance, aromatic dicarboxylic repeating units (Y1 and Y2 in Formula I are C(O)), aromatic hydroxycarboxylic repeating units (Y1 is O and Y2 is C(O) in Formula I), as well as various combinations thereof.
Aromatic hydroxycarboxylic repeating units, for instance, may be employed that are derived from aromatic hydroxycarboxylic acids, such as, 4-hydroxybenzoic acid; 4-hydroxy-4′-biphenylcarboxylic acid; 2-hydroxy-6-naphthoic acid; 2-hydroxy-5-naphthoic acid; 3-hydroxy-2-naphthoic acid; 2-hydroxy-3-naphthoic acid; 4′-hydroxyphenyl-4-benzoic acid; 3′-hydroxyphenyl-4-benzoic acid; 4′-hydroxyphenyl-3-benzoic acid, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof, and combination thereof. Particularly suitable aromatic hydroxycarboxylic acids are 4-hydroxybenzoic acid (“HBA”) and 6-hydroxy-2-naphthoic acid (“HNA”). When employed, repeating units derived from hydroxycarboxylic acids (e.g., HBA and/or HNA) typically constitute about 30 mol. % or more, in some embodiments from about 50 mol. % to 100 mol. %, and in some embodiments, from about 70 mol. % to 100 mol. % of the polymer.
In certain embodiments, the liquid crystalline polymer may contain only components derived from aromatic hydroxycarboxylic repeating units, such as HBA and HNA. In other embodiments, however, aromatic dicarboxylic repeating units may also be employed that are derived from aromatic dicarboxylic acids, such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4′-dicarboxybiphenyl, bis(4-carboxyphenyl)ether, bis(4-carboxyphenyl)butane, bis(4-carboxyphenyl)ethane, bis(3-carboxyphenyl)ether, bis(3-carboxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof, and combinations thereof. Particularly suitable aromatic dicarboxylic acids may include, for instance, terephthalic acid (“TA”), isophthalic acid (“IA”), and 2,6-naphthalenedicarboxylic acid (“NDA”). When employed, repeating units derived from aromatic dicarboxylic acids (e.g., IA, TA, and/or NDA) each typically constitute from about 1 mol. % to about 50 mol. %, in some embodiments from about 2 mol. % to about 40 mol. %, and in some embodiments, from about 5 mol. % to about 30 mol. % of the polymer.
Other repeating units may also be employed in the polymer. In certain embodiments, for instance, repeating units may be employed that are derived from aromatic diols, such as hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl (or 4,4′-biphenol), 3,3′-dihydroxybiphenyl, 3,4′-dihydroxybiphenyl, 4,4′-dihydroxybiphenyl ether, bis(4-hydroxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof, and combinations thereof. Particularly suitable aromatic diols may include, for instance, hydroquinone (“HQ”) and 4,4′-biphenol (“BP”). When employed, repeating units derived from aromatic diols (e.g., HQ and/or BP) each typically constitute from about 1 mol. % to about 30 mol. %, in some embodiments from about 2 mol. % to about 25 mol. %, and in some embodiments, from about 5 mol. % to about 20 mol. % of the polymer. Repeating units may also be employed, such as those derived from aromatic amides (e.g., acetaminophen (“APAP”)) and/or aromatic amines (e.g., 4-aminophenol (“AP”), 3-aminophenol, 1,4-phenylenediamine, 1,3-phenylenediamine, etc.). When employed, repeating units derived from aromatic amides (e.g., APAP) and/or aromatic amines (e.g., AP) typically constitute from about 0.1 mol. % to about 20 mol. %, in some embodiments from about 0.5 mol. % to about 15 mol. %, and in some embodiments, from about 1 mol. % to about 10 mol. % of the polymer. It should also be understood that various other monomeric repeating units may be incorporated into the polymer. For instance, in certain embodiments, the polymer may contain one or more repeating units derived from non-aromatic monomers, such as aliphatic or cycloaliphatic hydroxycarboxylic acids, dicarboxylic acids, diols, amides, amines, etc. Of course, in other embodiments, the polymer may be “wholly aromatic” in that it lacks repeating units derived from non-aromatic (e.g., aliphatic or cycloaliphatic) monomers.
In some embodiments, the polymer matrix may contain a “low naphthenic” liquid crystalline polymer having a low content of repeating units derived from naphthenic hydroxycarboxylic acids and naphthenic dicarboxylic acids, such as naphthalene-2,6-dicarboxylic acid (“NDA”), 6-hydroxy-2-naphthoic acid (“HNA”), or combinations thereof. That is, the total amount of repeating units derived from naphthenic hydroxycarboxylic and/or dicarboxylic acids (e.g., NDA, HNA, or a combination of HNA and NDA) can be about 15 mol. % or less, in some embodiments about 10 mol. % or less, in some embodiments about 6 mol. % or less, and in some embodiments, from 0 mol. % to about 5 mol. % of the polymer. In such embodiments, the polymer may contain repeating units derived from HBA in an amount of from about 40 mol. % to about 80 mol. %, and in some embodiments from about 45 mol. % to about 75 mol. %, and in some embodiments, from about 50 mol. % to about 70 mol. %. The polymer may also contain aromatic dicarboxylic acid(s) (e.g., IA and/or TA) in an amount of from about 1 mol. % to about 26 mol. %, and in some embodiments, from about 5 mol. % to about 20 mol. %, and/or aromatic diol(s) (e.g., BP and/or HQ) in an amount of from about 1 mol. % to about 20 mol. %, and in some embodiments, from about 4 mol. % to about 15 mol. %.
In other embodiments, the polymer matrix may contain a “high naphthenic” liquid crystalline polymer containing a relatively high content of repeating units derived from naphthenic hydroxycarboxylic acids and naphthenic dicarboxylic acids, such as naphthalene-2,6-dicarboxylic acid (“NDA”), 6-hydroxy-2-naphthoic acid (“HNA”), or combinations thereof. That is, the total amount of repeating units derived from naphthenic hydroxycarboxylic and/or dicarboxylic acids (e.g., NDA, HNA, or a combination of HNA and NDA) can be greater than about 15 mol. %, in some embodiments about 18 mol. % or more, and in some embodiments, from about 20 mol. % to about 60 mol. % of the polymer. In one particular embodiment, for instance, the repeating units derived from 6-hydroxy-2-naphthoic acid (“HNA”) may constitute from about 10 mol. % to about 40 mol. %, in some embodiments from about 15 mol. % to about 35 mol. %, and in some embodiments, from about 20 mol. % to about 30 mol. % of the polymer. In such embodiments, the liquid crystalline polymer may also contain various other monomers, such as aromatic hydroxycarboxylic acid(s) (e.g., HBA) in an amount of from about 20 mol. % to about 85 mol. %, in some embodiments from about 40 mol % to about 82 mol % and in some embodiments, from about 70 mol. % to about 80 mol. %. The polymer may also contain aromatic dicarboxylic acid(s) (e.g., IA and/or TA), such as in an amount of from about 0 mol. % to about 30 mol. %, and in some embodiments, from about 2 mol. % to about 25 mol. %, and/or aromatic diol(s) (e.g., BP and/or HQ), such as in an amount of from about 0 mol. % to about 40 mol. %, and in some embodiments, from about 2 mol. % to about 35 mol. %. In some embodiments, the high naphthenic liquid crystalline polymer contains a small amount of aromatic dicarboxylic acid in addition to a naphthenic hydroxycarboxylic acid and HBA. For instance, the liquid crystalline polymer can contain TA and/or IA in an amount from about 0.1 mol. % to about 5 mol. %, in some embodiments from about 0.2 mol. % to about 2 mol. %, and in some embodiments, from about 0.5 mol. % to about 1 mol. %.
In certain embodiments, all of the liquid crystalline polymers are “low naphthenic” polymers such as described above. In other embodiments, all of the liquid crystalline polymers are “high naphthenic” polymers such as described above. In some cases, blends of such polymers may also be used. For example, high naphthenic liquid crystalline polymers may constitute from about 50 wt. % to about 95 wt. %, in some embodiments from about 60 wt. % to about 90 wt. %, and in some embodiments, from about 75 wt. % to about 85 wt. % of the total amount of liquid crystalline polymers in the composition, and low naphthenic liquid crystalline polymers may constitute from about 5 wt. % to about 50 wt. %, in some embodiments from about 10 wt. % to about 40 wt. %, and in some embodiments, from about 15 wt. % to about 25 wt. % of the total amount of liquid crystalline polymers in the composition. In other embodiments, low naphthenic liquid crystalline polymers may constitute from about 50 wt. % to about 99 wt. %, in some embodiments from about 80 wt. % to about 97 wt. %, and in some embodiments, from about 90 wt. % to about 95 wt. % of the total amount of liquid crystalline polymers in the composition, and high naphthenic liquid crystalline polymers may constitute from about 1 wt. % to about 50 wt. %, in some embodiments from about 3 wt. % to about 20 wt. %, and in some embodiments, from about 5 wt. % to about 10 wt. % of the total amount of liquid crystalline polymers in the composition.
As indicated above, an impact modifier is also employed within the polymer composition. Typically, impact modifier(s) constitute from about 20 parts to about 150 parts, in some embodiments from about 25 to about 130 parts, and in some embodiments, from about 30 to about 120 parts by weight per 100 parts by weight of the polymer matrix. For example, the impact modifiers may constitute from about 15 wt. % to about 50 wt. %, in some embodiments from about 18 wt. % to about 45 wt. %, and in some embodiments, from about 20 wt. % to about 40 wt. % of the polymer composition.
To help impart the desired combination of softness, flexibility, and scratch resistance, it is generally desired that the impact modifier is a polymer that contains a (meth)acrylic component. As used herein, the term “(meth)acrylic” includes acrylic and methacrylic monomers, as well as salts or esters thereof, such as acrylate and methacrylate monomers. The (meth)acrylic component may, for example, constitute from about 5 wt. % to about 45 wt. %, in some embodiments from about 10 wt. % to about 42 wt. %, and in some embodiments, from about 20 wt. % to about 40 wt. % of the impact modifier.
The (meth)acrylic component may be derived from one or more types of monomeric components. In one embodiment, for example, the (meth)acrylic component may be derived entirely or in part from an “epoxy-functionalized” (meth)acrylic component. The term “epoxy-functionalized” generally means that the component contains, on average, two or more epoxy functional groups per molecule. For example, suitable epoxy-functionalized (meth)acrylic monomers may include, but are not limited to, those containing 1,2-epoxy groups, such as glycidyl acrylate and glycidyl methacrylate. Other suitable epoxy-functionalized monomers include allyl glycidyl ether, glycidyl ethacrylate, and glycidyl itoconate. When employed, the epoxy-functionalized (meth)acrylic monomer(s) typically constitute from about 1 wt. % to about 35 wt. %, in some embodiments from about 2 wt. % to about 20 wt. %, and in some embodiments, from about 4 wt. % to about 12 wt. % of the impact modifier.
Of course, (meth)acrylic monomer(s) may also be employed that are not epoxy-functionalized. Examples of such (meth)acrylic monomers may include methyl acrylate, ethyl acrylate, propyl acrylate (e.g., n-propyl acrylate, i-propyl acrylate, etc.), butyl acrylate (e.g., n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butyl acrylate, etc.), amyl acrylate (e.g., n-amyl acrylate, i-amyl acrylate, etc.), isobornyl acrylate, hexyl acrylate (e.g., n-hexyl acrylate), 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, octyl acrylate (e.g., n-octyl acrylate), decyl acrylate (e.g., n-decyl acrylate), methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, propyl methacrylate (e.g., n-propyl methacrylate, i-propyl methacrylate, etc.), butyl methacrylate (e.g., n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, etc.), amyl methacrylate (e.g., n-amyl methacrylate, i-amyl methacrylate, etc.), hexyl methacrylate (e.g., n-hexyl methacrylate), 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, etc., as well as combinations thereof. When employed, the non-epoxy-functionalized (meth)acrylic monomer(s) typically constitute from about 5 wt. % to about 40 wt. %, in some embodiments from about 10 wt. % to about 35 wt. %, and in some embodiments, from about 15 wt. % to about 30 wt. % of the impact modifier.
The impact modifier may also contain an olefinic monomeric unit that is derived from one or more α-olefins. When employed, such α-olefin monomer(s) typically constitute from about 50 wt. % to about 90 wt. %, in some embodiments from about 60 wt. % to about 85 wt. %, and in some embodiments, from about 65 wt. % to about 75 wt. % of the copolymer. Examples of such monomers include, for instance, linear and/or branched α-olefins having from 2 to 20 carbon atoms and typically from 2 to 8 carbon atoms. Specific examples include ethylene, propylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired α-olefin monomers are ethylene and propylene.
In one particular embodiment, for example, the impact modifier may be a random copolymer of an olefinic monomer (e.g., ethylene) and an epoxy-functionalized (meth)acrylic monomer (e.g., glycidyl methacrylate). One commercially available example of such an impact modifier is Lotader® AX8840 (8 wt. % glycidyl methacrylate and 92 wt. % ethylene). In another embodiment, the impact modifier may be a terpolymer formed from an olefin monomer (e.g., ethylene), an epoxy-functionalized (meth)acrylic monomer (e.g., glycidyl methacrylate), and a non-epoxy functionalized (meth)acrylic monomer (e.g., butyl acrylate, methyl acrylate, butyl methacrylate, methyl methacrylate, etc.). Commercially available examples of such impact modifiers include Elvaloy® PTW (5 wt. % glycidyl methacrylate, 28 wt. % butyl acrylate, and 67 wt. % ethylene), Lotader® AX8900 (8 wt. % glycidyl methacrylate, 24 wt. % methyl acrylate, 68 wt. % ethylene), Lotader® AX8750 (5 wt. % glycidyl methacrylate, 25 wt. % butyl acrylate, and 70 wt. % ethylene), and Lotader® AX8750T (5 wt. % glycidyl methacrylate, 27 wt. % butyl acrylate, and 68 wt. % ethylene).
The resulting melt flow index of the impact modifier may vary, but is typically from about 1 to about 50 grams per 10 minutes (“g/10 min”), in some embodiments from about 2 to about 40 g/10 min, and in some embodiments, from about 3 to about 25 g/10 min, as determined in accordance with ISO 1133-1:2022 at a load of 2.16 kg and temperature of 190° C.
Although by no means required, the polymer composition may also contain an inorganic filler that is distributed within the polymer matrix. Such fillers generally constitute from about 10 wt. % to about 40 wt. %, in some embodiments from about 15 wt. % to about 38 wt. %, and in some embodiments, from about 20 wt. % to about 35 wt. % of the polymer composition. Any of a variety of different types of inorganic fillers may generally be employed, such as those formed from a natural and/or synthetic silicate mineral, such as talc, mica, halloysite, kaolinite, illite, montmorillonite, vermiculite, palygorskite, pyrophyllite, calcium silicate, aluminum silicate, wollastonite, etc.; sulfates; carbonates; phosphates; fluorides, borates; and so forth. In certain cases, the inorganic filler may have a certain hardness value to help improve the mechanical strength, adhesive strength, and surface properties of the composition, which enables the composition to be uniquely suited to form small components, such as in a camera module. For instance, the hardness values may be about 2.0 or more, in some embodiments about 2.5 or more, in some embodiments about 3.0 or more, in some embodiments from about 3.0 to about 11.0, in some embodiments from about 3.5 to about 11.0, and in some embodiments, from about 4.5 to about 6.5 based on the Mohs hardness scale.
The nature of the inorganic filler may also vary as desired. In one embodiment, for instance, the polymer composition may contain inorganic filler particles that are distributed within the polymer matrix. For instance, the particles may be formed from a natural and/or synthetic mineral, such as talc, mica, halloysite, kaolinite, illite, montmorillonite, vermiculite, palygorskite, pyrophyllite, calcium silicate, aluminum silicate, wollastonite, etc. Other suitable inorganic filler particles may include, for instance, barium sulfate, calcium sulfate, silica, alumina, calcium carbonate, etc. The particles may possess a variety of different forms and shapes depending upon the desired performance. For instance, the particles may be in the shape of a sphere, crystal, rod, disk, tube, string, etc. In one embodiment, for example, the particles may be generally spherical in that the aspect ratio (ratio of the median diameter to the thickness) is from about 0.7 to about 1.3, in some embodiments from about 0.8 to about 1.2, in some embodiments from about 0.9 to about 1.1 (e.g., 1). Regardless of their particular shape, however, the particles are generally selectively controlled to have a certain a median (D50) diameter, such as about 5 micrometers or less, in some embodiments from about 0.01 to about 4 micrometers, in some embodiments from about 0.05 to about 3 micrometers, and in some embodiments, from about 0.1 to about 2.5 micrometers, such as determined by a laser diffraction particle size analyzer (e.g., Mastersizer 3000) or sedimentation analysis (e.g., Sedigraph 5120). The particles may also have a narrow size distribution. That is, at least about 70% by volume of the particles, in some embodiments at least about 80% by volume of the particles, and in some embodiments, at least about 90% by volume of the particles may have a size within the ranges noted above. Furthermore, within the general size ranges noted above, it may sometimes be desirable to employ a blend of particles having different sizes to achieve the target properties. The particles may also have a controlled specific surface area, such as from about 1 to about 50 square meters per gram (m2/g), in some embodiments from about 2 to about 20 m2/g, and in some embodiments, from about 4 to about 12 m2/g. The term “specific surface area” generally refers to surface area as determined by the physical gas adsorption (B.E.T.) method of Bruanauer, Emmet, and Teller, Journal of American Chemical Society, Vol. 60, 1938, p. 309, with nitrogen as the adsorption gas. The moisture content may also be relatively low, such as about 5% or less, in some embodiments about 3% or less, and in some embodiments, from about 0.1 to about 1% as determined in accordance with ISO 787-2:1981 at a temperature of 105° C.
Various other types of inorganic fillers may also be employed in the polymer composition. In one embodiment, for instance, mineral fibers (or “whiskers”) may be employed, such as those that are derived from silicates, such as neosilicates, sorosilicates, inosilicates (e.g., calcium inosilicates, such as wollastonite; calcium magnesium inosilicates, such as tremolite; calcium magnesium iron inosilicates, such as actinolite; magnesium iron inosilicates, such as anthophyllite; etc.), phyllosilicates (e.g., aluminum phyllosilicates, such as palygorskite), tectosilicates, etc.; sulfates, such as calcium sulfates (e.g., dehydrated or anhydrous gypsum); mineral wools (e.g., rock or slag wool); and so forth. Particularly suitable are fibers derived from inosilicates, such as wollastonite, which are commercially available from Nyco Minerals under the trade designation Nyglos® (e.g., Nyglos® 4W or Nyglos® 8). The mineral fibers may have a median diameter of from about 1 to about 35 micrometers, in some embodiments from about 2 to about 20 micrometers, in some embodiments from about 3 to about 15 micrometers, and in some embodiments, from about 7 to about 12 micrometers. In addition to possessing the size characteristics noted above, the mineral fibers may also have a relatively high aspect ratio (average length divided by median diameter) to help further improve the mechanical properties and surface quality of the resulting polymer composition. For example, the mineral fibers may have an aspect ratio of from about 2 to about 100, in some embodiments from about 2 to about 50, in some embodiments from about 3 to about 20, and in some embodiments, from about 4 to about 15. The volume average length of such mineral fibers may, for example, range from about 1 to about 200 micrometers, in some embodiments from about 2 to about 150 micrometers, in some embodiments from about 5 to about 100 micrometers, and in some embodiments, from about 10 to about 50 micrometers.
A wide variety of additional additives can also be included in the polymer composition, such as lubricants, thermally conductive fillers, pigments (e.g., carbon black), flow modifiers, antioxidants, stabilizers, surfactants, waxes, flame retardants, anti-drip additives, nucleating agents, and other materials added to enhance properties and processability. Lubricants, for example, may be employed in the polymer composition that are capable of withstanding the processing conditions of the liquid crystalline polymer without substantial decomposition. Examples of such lubricants include fatty acids esters, the salts thereof, esters, fatty acid amides, organic phosphate esters, and hydrocarbon waxes of the type commonly used as lubricants in the processing of engineering plastic materials, including mixtures thereof. Suitable fatty acids typically have a backbone carbon chain of from about 12 to about 60 carbon atoms, such as myristic acid, palmitic acid, stearic acid, arachic acid, montanic acid, octadecinic acid, parinric acid, and so forth. Suitable esters include fatty acid esters, fatty alcohol esters, wax esters, glycerol esters, glycol esters and complex esters. Fatty acid amides include fatty primary amides, fatty secondary amides, methylene and ethylene bisamides and alkanolamides such as, for example, palmitic acid amide, stearic acid amide, oleic acid amide, N,N′-ethylenebisstearamide and so forth. Also suitable are the metal salts of fatty acids such as calcium stearate, zinc stearate, magnesium stearate, and so forth; hydrocarbon waxes, including paraffin waxes, polyolefin and oxidized polyolefin waxes, and microcrystalline waxes. Particularly suitable lubricants are acids, salts, or amides of stearic acid, such as pentaerythritol tetrastearate, calcium stearate, or N,N′-ethylenebisstearamide. When employed, the lubricant(s) typically constitute from about 0.05 wt. % to about 1.5 wt. %, and in some embodiments, from about 0.1 wt. % to about 0.5 wt. % (by weight) of the polymer composition.
One beneficial aspect of the present invention is that good mechanical properties may be achieved without adversely impacting the dimensional stability of the resulting part. To help ensure that this dimensional stability is maintained, it is generally desirable that the polymer composition remains substantially free of conventional fibrous fillers, such as glass fibers. Thus, if employed at all, glass fibers typically constitute no more than about 10 wt. %, in some embodiments no more than about 5 wt. %, and in some embodiments, from about 0.001 wt. % to about 3 wt. % of the polymer composition.
Regardless of the components employed, they may be combined together using any of a variety of different techniques as is known in the art. In one particular embodiment, for example, the liquid crystalline polymer, impact modifier, and other optional additives are melt processed as a mixture within an extruder to form the polymer composition. The mixture may be melt-kneaded in a single-screw or multi-screw extruder, such as at a temperature of from about 210° C. to about 360° C. In one embodiment, the mixture may be melt processed in an extruder that includes multiple temperature zones. The temperature of individual zones is typically set within about −60° C. to about 25° C. relative to the melting temperature of the polymer. By way of example, the mixture may be melt processed using a twin screw extruder such as a Leistritz 18-mm co-rotating fully intermeshing twin screw extruder. A general purpose screw design can be used to melt process the mixture. In one embodiment, the mixture including all of the components may be fed to the feed throat in the first barrel by means of a volumetric feeder. In another embodiment, different components may be added at different addition points in the extruder, as is known. For example, the polymer may be applied at the feed throat, and certain additives (e.g., impact modifier) may be supplied at the same or different temperature zone located downstream therefrom. Regardless, the resulting mixture can be melted and mixed then extruded through a die. The extruded polymer composition can then be quenched in a water bath to solidify and granulated in a pelletizer followed by drying.
The polymer composition may be readily formed into a molded component for use in various product applications. The molded component may be formed using a variety of different molding techniques. Suitable molding techniques may include, for instance, injection molding, low-pressure injection molding, extrusion compression molding, gas injection molding, foam injection molding, low-pressure gas injection molding, low-pressure foam injection molding, gas extrusion compression molding, foam extrusion compression molding, extrusion molding, foam extrusion molding, compression molding, foam compression molding, gas compression molding, etc. For example, an injection molding system may be employed that includes a mold within which the polymer composition may be injected. The time inside the injector may be controlled and optimized so that polymer matrix is not pre-solidified. When the cycle time is reached and the barrel is full for discharge, a piston may be used to inject the composition to the mold cavity. Compression molding systems may also be employed. As with injection molding, the shaping of the polymer composition into the desired article also occurs within a mold. The composition may be placed into the compression mold using any known technique, such as by being picked up by an automated robot arm. The temperature of the mold may be maintained at or above the solidification temperature of the polymer matrix for a desired time period to allow for solidification. The molded product may then be solidified by bringing it to a temperature below that of the melting temperature. The resulting product may be de-molded. The cycle time for each molding process may be adjusted to suit the polymer matrix, to achieve sufficient bonding, and to enhance overall process productivity.
The polymer composition is particularly well suited for use as a damper in a camera module. The camera module itself may be used in a variety of different applications, such as portable electronic devices (e.g., mobile phones, portable computers, tablets, watches, etc.), computers, televisions, automotive parts, etc. In one particular embodiment, the polymer composition may be employed as a damper of a camera module of a wireless communication device (e.g., cellular telephone). Generally speaking, the damper may be disposed between the housing unit and the lens unit so that it is configured to help act as a shock absorbing material to minimize the formation of dents and/or scratches on a surface of the camera module caused by collision of portions of the module (e.g., lens unit, housing unit, ball members, etc.), as well as help reduce noise.
Referring to
The actuator unit 200 may be configured to move the lens unit 300 in one or more directions. For example, the actuator unit 200 may be configured to move the lens unit 300 in a direction of an optical axis (Z axis direction with reference to
The first actuator 210 may be mounted in the housing 110 and a first frame 310 of the lens unit 300. For example, a portion of the first actuator 210 may be mounted on the first side surface of the housing 110 and a remaining portion of the first actuator 210 may be mounted on a first side surface of the first frame 310. The first actuator 210 may include an element for moving the lens unit 300 in the direction of the optical axis. As an example, the first actuator 210 may include the first coil 212, a first permanent magnet 214, a first substrate 216, and a first sensor 218. The first coil 212 and the first sensor 218 may be formed on the first substrate 216. The first substrate 216 may be mounted on the first side surface of the housing 110, and the first permanent magnet 214 may be mounted on the first side surface of the first frame 310 facing the first substrate 216. The first actuator 210 may allow relative movement of the first frame 310 and a lens barrel 340 with respect to the housing 110 by changing intensity and a direction of magnetic force generated between the first coil 212 and the first permanent magnet 214. In addition, the first actuator 210 may detect a position of the first frame 310 based on a change in a magnetic flux detected by the first sensor 218.
The second actuator 220 may be mounted in the housing 110 and a third frame 330 of the lens unit 300. For example, portions of the second actuator 220 may be mounted on the second through fourth side surfaces of the housing 110, respectively, and a remaining portion of the second actuator 220 may be mounted on second through fourth side surfaces of the third frame 330. The second actuator 220 may include an element for moving the lens unit 300 in the direction perpendicular with respect to the optical axis. As an example, the second actuator 220 may include a plurality of second coils 222, a plurality of second permanent magnets 224, a second substrate 226, and one or more second sensors 228. The plurality of second coils 222 and the one or more second sensors 228 may be formed on the second substrate 226. The second substrate 226 may be generally formed to be mounted to surround the second through fourth side surfaces of the housing 110. The plurality of second permanent magnets 224 may be mounted on the second through fourth side surfaces of the third frame 330 to face three surfaces of the second substrate 226, respectively. The second actuator 220 may allow relative movement of the second frame 320 and the third frame 330 with respect to the first frame 310 by changing intensity and a direction of magnetic force generated between the plurality of second coils 222 and the plurality of second permanent magnets 224. For reference, the lens barrel 340 may move in the same direction as that of the second frame 320 and the third frame 330 by movement of the second frame 320 and the third frame 330. The second actuator 220 may detect positions of the second frame 320 and the third frame 330 based on a change in a magnetic flux detected by the second sensor 228.
The lens unit 300 may be mounted in the housing unit 100. For example, the lens unit 300 may be accommodated in an accommodation space formed by the housing 110 and the shield can 120 in a manner in which the lens unit 300 may move in at least three axis directions. The lens unit 300 may contain a plurality of frames. For example, the lens unit 300 may include the first frame 310, the second frame 320, and the third frame 330.
The first frame 310 may be configured to move with respect to the housing 110. As an example, the first frame 310 may move in a height direction (Z axis direction with reference to
The third frame 330 may be mounted in the second frame 320. For example, the third frame 330 may be mounted on a top surface of the second frame 320. The third frame 330 may be configured to move in the direction perpendicular with respect to the optical axis, with respect to the second frame 320. For example, the third frame 330 may move in the direction (X axis direction with reference to
The lens unit 300 may include a lens barrel 340 that contains one or more lenses. The lens barrel 340 may be mounted in the third frame 330. For example, the lens barrel 340 may be inserted into the third frame 330 to move integrally with the third frame 330. The lens barrel 340 may be configured to move in the direction of the optical axis and the direction perpendicular with respect to the optical axis. For example, the lens barrel 340 may move in the direction of the optical axis by the first actuator 210, and may move in the direction perpendicular with respect to the optical axis by the second actuator 220.
The lens unit 300 may further include a cover member 350, a ball stopper 360, and a magnetic body 370. The cover member 350 may be configured to prevent the second frame 320 and the third frame 330 from escaping from the interior of the first frame 310. For example, the cover member 350 may be combined with the first frame 310 to suppress escaping of the second frame 320 and the third frame 330 upwardly of the first frame 310. The ball stopper 360 may be mounted in the first frame 310. The ball stopper 360 may be disposed to obscure the first guide grooves 312 of the first frame 310 to suppress escaping of first ball members 410 mounted in the first guide grooves 312 therefrom.
The magnetic body 370 may be mounted in the first frame 310. For example, the magnetic body 370 may be mounted in at least one of the second through fourth side surfaces of the first frame 310 to generate magnetic attractive force between the second coil 222 and the second permanent magnet 224 of the second actuator 220. The magnetic body 370 configured as above may fix positions of the second frame 320 and the third frame 330 with respect to the first frame 310 in an inactive state of the actuator unit 200. For example, the lens unit 300 may be maintained at a predetermined position inside the housing 110 by magnetic attractive force between the magnetic body 370 and the second coil 222.
The ball member 400 may be configured to smoothly move the lens unit 300. For example, the ball member 400 may be configured to smoothly move the lens unit 300 in the direction of the optical axis and the direction perpendicular with respect to the optical axis. The ball member 400 may be divided into first ball members 410, second ball members 420, and third ball members 430 based on a disposition position. As an example, the first ball members 410 may be disposed in each of the first guide grooves 312 of the first frame 310 to smoothly move the first frame 310 in the direction of the optical axis. As another example, the second ball member 420 may be disposed in each of the second guide grooves 314 of the first frame 310 to smoothly move the second frame 320 in a direction perpendicular with respect to the optical axis. As still another example, the third ball member 430 may be disposed in each of the third guide grooves 322 of the second frame 320 to smoothly move the third frame 330 in another direction perpendicular with respect to the optical axis. For reference, although not illustrated in
As noted above, the camera module 10 also contains one or more dampers 500. Each damper 500 may be configured to reduce noise and/or surface damage caused by collision of portions of the camera module, such as by movement of the lens unit 300. For example, the damper 500 may be configured to reduce collision damage and/or noise caused by moving the lens unit 300 in the direction of the optical axis and the direction perpendicular with respect to the optical axis due to external impacts. As an example, the damper 500 may be formed in the cover member 350 to reduce collision noise and/or damage generated between the lens unit 300 and the housing unit 100.
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As discussed herein, the polymer composition of the present invention is particularly well suited for use in a damper of a camera module, such as one or more of the dampers 500 (including the fixing unit 502 and/or modification unit 504 shown in
The present invention may be better understood with reference to the following examples.
Melt Viscosity: The melt viscosity (Pa-s) may be determined in accordance with ISO 11443:2021 at a shear rate of 1,000 s−1 or 400 s−1 and temperature 15° C. above the melting temperature using a Dynisco LCR7001 capillary rheometer. The rheometer orifice (die) had a diameter of 1 mm, length of 20 mm, L/D ratio of 20.1, and an entrance angle of 180°. The diameter of the barrel was 9.55 mm+0.005 mm and the length of the rod was 233.4 mm.
Melting Temperature: The melting temperature (“Tm”) may be determined by differential scanning calorimetry (“DSC”) as is known in the art. The melting temperature is the differential scanning calorimetry (DSC) peak melt temperature as determined by ISO 11357-2:2020. Under the DSC procedure, samples were heated and cooled at 20° C. per minute as stated in ISO Standard 10350 using DSC measurements conducted on a TA Q2000 Instrument.
Deflection Temperature Under Load (“DTUL”): The deflection under load temperature may be determined in accordance with ISO 75-2:2013 (technically equivalent to ASTM D648-18). More particularly, a test strip sample having a length of 80 mm, thickness of 10 mm, and width of 4 mm may be subjected to an edgewise three-point bending test in which the specified load (maximum outer fibers stress) was 1.8 Megapascals. The specimen may be lowered into a silicone oil bath where the temperature is raised at 2° C. per minute until it deflects 0.25 mm (0.32 mm for ISO Test No. 75-2:2013).
Tensile Modulus, Tensile Stress, and Tensile Elongation: Tensile properties may be tested according to ISO 527:2019 (technically equivalent to ASTM D638-14). Modulus and strength measurements may be made on the same test strip sample having a length of 80 mm, thickness of 10 mm, and width of 4 mm. The testing temperature may be 23° C., and the testing speeds may be 1 or 5 mm/min.
Flexural Modulus, Flexural Stress, and Flexural Elongation: Flexural properties may be tested according to ISO Test No. 178:2019 (technically equivalent to ASTM D790-10). This test may be performed on a 64 mm support span. Tests may be run on the center portions of uncut ISO 3167 multi-purpose bars. The testing temperature may be 23° C. and the testing speed may be 2 mm/min.
Charpy Impact Strength: Charpy properties may be tested according to ISO 179-1:2010) (technically equivalent to ASTM D256-10, Method B). This test may be run using a Type 1 specimen size (length of 80 mm, width of 10 mm, and thickness of 4 mm). When testing the notched impact strength, the notch may be a Type A notch (0.25 mm base radius). Specimens may be cut from the center of a multi-purpose bar using a single tooth milling machine. The testing temperature may be 23° C.
Rockwell Hardness: Rockwell hardness is a measure of the indentation resistance of a material and may be determined in accordance with ASTM D785-08 (Scale M). Testing is performed by first forcing a steel ball indentor into the surface of a material using a specified minor load. The load is then increased to a specified major load and decreased back to the original minor load. The Rockwell hardness is a measure of the net increase in depth of the indentor, and is calculated by subtracting the penetration divided by the scale division from 130.
Scratch Resistance: Five (5) ISO tensile bars are formed from a particular sample. One of the tensile bars is held in hand like a pencil and rubbed back and forth 20 times against the surface of the other ISO tensile bars. For each bar, the scratch resistance is rated on a scale of 1 to 5, with a “5” rating means nearly no scratches and a “1” rating meaning numerous scratches. The average scratch resistance is then determined and recorded.
Samples 1-5 are formed from various weight percentages of LCP 1, colorant, Impact Modifier 1, Mineral 1, and a lubricant, as shown in Table 1. LCP 1 is formed from 62.5 mol. % HBA, 5 mol. % HNA, 16.4 mol. % TA, 11.2 mol. % BP, and 5 mol. % APAP. Mineral 1 is barium sulfate particles having a median particle size of 4 micrometers. Impact Modifier 1 is a terpolymer of ethylene, n-butyl acrylate, and glycidyl methacrylate having a melt flow index of 12 g/10 min, Shore A hardness of 73 (equates to a Shore D hardness of about 23), a glycidyl methacrylate monomer content of about 5 wt. %, and a butyl acrylate content of about 28 wt. %.
Parts are injection molded from the samples of Examples 1-5 into plaques and tested for various thermal and mechanical properties. The results are set forth below in Table 2.
Samples 6-10 are formed from various weight percentages of LCP 1, colorant, Impact Modifier 1, Mineral 1, and a lubricant, as shown in Table 3.
Parts are injection molded from the samples of Examples 6-10 into plaques and tested for various thermal and mechanical properties. The results are set forth below in Table 4.
Samples 11-17 are formed from various weight percentages of LCP 1, colorant, Impact Modifier 1, Mineral 1, Mineral 2, Mineral 3, and a lubricant, as shown in Table 5. Mineral 2 is wollastonite fibers (Nyglos® 8) and Mineral 3 is talc particles having a median particle diameter of 1.9 μm.
Parts are injection molded from the samples of Examples 11-17 into plaques and tested for various thermal and mechanical properties. The results are set forth below in Table 6.
Samples 18-22 are formed from various weight percentages of LCP 1, LCP 2, colorant, Impact Modifier 2, and Mineral 4, as shown in Table 7. LCP 2 is formed from 73 mol. % HBA and 27 mol. % HNA. Mineral 4 is talc particles having a median particle size of 7.5 μm. Impact Modifier 2 is a random copolymer of ethylene and glycidyl methacrylate having a melt flow index of 5 g/10 min, a Shore D hardness of about 50, and a glycidyl methacrylate monomer content of about 8 wt. %.
Parts are injection molded from the samples of Examples 18-21 into plaques and tested for various thermal and mechanical properties. The results are set forth below in Table 8.
These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.
The present application is based upon and claims priority to U.S. Provisional Patent Application Ser. No. 63/589,067, having a filing date of Oct. 10, 2023, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63589067 | Oct 2023 | US |
