KR20170101750A - Functional film - Google Patents

Abstract

The present invention provides a functional film having a very small thickness unevenness. The functional film comprises a thermoplastic elastomer, and has the thickness of 10 to 100 m, and tolerance in thickness unevenness is 2 m or less. By a coating method, the solid content of the thermoplastic elastomer in a solution containing the thermoplastic elastomer and the thickness of applied coating are kept constant, further, the temperature of the solution is kept at a constant value of 10 to 40 deg. C and the viscosity of the solution is kept at a constant value of 100 to 50,000 mPas while being made into a film.

Description

Functional Film {FUNCTIONAL FILM}

The present invention relates to a functional film comprising a thermoplastic elastomer.

It is known to use a functional film including a thermoplastic elastomer, for example, as a vibrating-member supporting member of a loudspeaker and a vibration damping material application requiring acoustic characteristics (see, for example, Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2004-269756 Japanese Patent Laid-Open No. 2001-59057

In order to improve the sound quality of the speaker in the above-mentioned vibration damper application, it is required to minimize the thickness unevenness of the functional film to be used and to make the thickness uniform.

However, since the thermoplastic elastomer has a high molecular weight of about 100,000 to 500,000 and a large viscosity fluctuation during melting, it is difficult to obtain a film having a uniform thickness, and it is difficult to provide a stable sound quality.

An object of the present invention is to provide a functional film having a very small thickness variation.

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained the following findings. That is, it is known that the thickness unevenness of a film obtained by controlling the solid content concentration, viscosity and the like in a solution containing the thermoplastic elastomer can be suppressed within a desired range by the coating method.

The present invention is based on the knowledge of the present inventor, and means for solving the above-mentioned problems are as follows.

<1> A functional film comprising a thermoplastic elastomer and having a thickness of 10 to 100 μm and a tolerance of 2 μm or less.

<2> The solid content of the thermoplastic elastomer in the solution containing the thermoplastic elastomer and the applied thickness of the coating in the solution containing the thermoplastic elastomer are kept constant, and the temperature of the solution is 10 to 40 DEG C and the viscosity is 100 to 50,000 mPa < / RTI > &lt; RTI ID = 0.0 &gt; m / s. &lt; / RTI &gt;

<3> The solution according to <2>, wherein the solution contains 10 to 50% by weight of the thermoplastic elastomer.

(4) The thermoplastic elastomer is at least one of urethane, polyester, polyamide, olefin and styrene.

<5> The thermoplastic elastomer is a functional film according to <4> which is a polyurethane elastomer (TPU).

&Lt; 6 > The functional film according to < 1 >, which is used for a vibration system supporting member of a speaker.

&Lt; 7 > The functional film according to < 2 >, which is used for a vibration system supporting member of a speaker.

<8> The vibration damping material according to <1>, wherein the thermoplastic elastomer is at least one of urethane, polyester, polyamide, olefin and styrene.

<9> The vibration film according to <2>, wherein the thermoplastic elastomer is at least one of urethane, polyester, polyamide, olefin and styrene.

<10> A functional film according to <2>, wherein the thermoplastic elastomer is a polyurethane elastomer (TPU).

According to the present invention, it is possible to provide a high-precision functional film having a thickness tolerance of 2 mu m or less and having a very small thickness unevenness.

This makes it possible to obtain good sound quality in applications where the functional film such as a vibration damper is used.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing changes in the storage modulus at a temperature between 0 and 80 占 폚 when the hardness is different in the ester type polyurethane film of the present invention. Fig.
Fig. 2 is a graph showing changes in the storage modulus at low temperatures at 0 to 80 캜 when the hardness of the ether type polyurethane film of the present invention is changed.
Fig. 3 is a graph showing changes in the storage modulus at low temperature at 0 to 80 캜 when the hardness is different in the polyester film of the present invention. Fig.

The functional film of the present invention comprises a thermoplastic elastomer and has a thickness of 10 to 100 占 퐉 and a tolerance (thickness unevenness) of 2 占 퐉 or less, more preferably 1 占 퐉 or less.

By setting the tolerance within 2 占 퐉, it is possible to suppress the fluctuation of the stress when the film is stretched to be very small, and to improve the sound quality of the speaker when used for the vibration damper application. In other words, when the tolerance exceeds 2 탆, it is difficult to suppress the fluctuation of the stress to this range, and it becomes impossible to provide the speaker with sufficiently good sound quality.

When the thickness is less than 10 mu m, it is difficult to apply it in a desired application, while when it exceeds 100 mu m, it becomes difficult to manufacture and, in terms of cost, it is not preferable to make it thick.

The thickness of the functional film can be measured in accordance with JIS Z1072 using a commercially available film thickness measuring machine, and an average value obtained by measuring 30 points randomly in the obtained 1 m x 1 m film is employed. The tolerance is the difference between the maximum value and the minimum value.

The stress variation can be measured on the basis of JIS K7127. In the above-mentioned film of 1 m 占 1 m, the difference between the values measured at five random places is regarded as a variation value. In order to stably provide a good sound quality, the stiffness of a stable film is required, and the index is generally expressed by the elastic modulus. However, since the stiffness changes as the film becomes thicker, it is required to stabilize the stress during the stretching described above. When the stress at the time of elongation is stable, the storage elastic modulus at a temperature that can be assumed in a living environment of 0 to 80 ° C is also stable, and the provision of good sound quality, that is, the sound characteristic is excellent.

The hardness of the film is not particularly limited. In other words, if the thickness tolerance is within 2 占 퐉, good sound quality can be provided without being affected by high and low hardness.

The thermoplastic elastomer of the functional film of the present invention is produced by a coating method. The thermoplastic elastomer can be produced by an extrusion method. In the extrusion method, however, solid powder or pellets are softened and melted in a heating cylinder and extruded into a metal mold having a screw slit formed therein. They have a large molecular weight and a large variation in viscosity at the time of melting. This variation in viscosity causes thickness unevenness at the time of molding, and it is difficult to obtain a film having a uniform thickness. In other words, in the extrusion method, only a solid component such as powder or pellets is used. Therefore, there is no method other than increasing the film forming accuracy in order to control the film thickness. In order to produce a film having a uniform thickness, It is very difficult to have.

On the other hand, the coating method is a method in which a solution is coated with a certain weight (thickness) and the solvent in the solution is volatilized to thereby use a solute-only coating. Therefore, even if thickness unevenness occurs due to the solution, By adjusting the viscosity, thickness irregularity can be reduced.

However, it is not always possible to accommodate the thickness irregularities within the desired range of the present invention by the coating method. As a result of repeated trial and error by the inventors of the present invention, the following conditions are appropriate. That is, the solid content of the thermoplastic elastomer and the applied thickness of the thermoplastic elastomer in the solution containing the thermoplastic elastomer are kept constant, while the temperature of the solution is maintained at 10 to 40 ° C and the viscosity is kept constant in the range of 100 to 50,000 mPa · s Film.

The concentration of the thermoplastic elastomer in the solution is preferably 10 to 50% by weight. If the content is less than 10% by weight, unevenness of the film may occur, resulting in difficulty in imparting an apparent quality. On the other hand, if the content is more than 50% by weight, viscosity increases and it becomes difficult to suppress thickness irregularity within a desired range of the present invention.

Similarly, when the viscosity is less than 100 mPa s, it is difficult to maintain the apparent quality of the film. When the viscosity exceeds 50,000 mPa · s, it becomes difficult to suppress the thickness variation within a desired range. The viscosity can be measured in accordance with JIS Z7117-1.

When the temperature of the solution is outside the above-mentioned range, the viscosity changes and the thickness irregularity may not be controlled within a desired range. Therefore, the temperature is set within the above-mentioned temperature range which can be assumed as room temperature.

The solid content and the coating thickness of the thermoplastic elastomer in the solution containing the thermoplastic elastomer differ depending on the performance and scale of the production apparatus to be used and can not be specifically defined. For the solid content, for example, a thermoplastic elastomer (Tolerance) of the film is 2 占 퐉, if the thickness unevenness of the applied thickness is 8 占 퐉 in the solution containing 25% .

In order to make the thickness of the obtained film uniform, the liquid pressure of the solution must be maintained at a constant pressure in order to apply the solution in a predetermined amount. For example, in the case of a comma coater, To be constant.

The solid content is a condition that it is kept constant as described above in that a uniform amount of solids can not be obtained if the solid content in the solution is not constant during the production even if a certain amount of the solution is applied. Particularly, the solvent used for the solution is mainly an organic solvent, which is liable to volatilize, and because the solids content may fluctuate due to the volatilization of the solvent, it is not easy to keep it constant. Thereby, during the production of the film, the solution is fed from a hermetically sealed container.

Since the coating amount (thickness) is determined by the width of the gap, such as the gap between the backup roll and the knife roll in a roll knife coater, the thickness of the formed film is measured, , The thickness of the applied coating in the solution state during the coating process is measured and adjusted to a predetermined uniform coating thickness.

The coater used for the coating is not particularly limited and may be suitably selected according to the intended use. Examples of the coater include a gravure coater, a reverse roll coater, a kiss coater, a roll knife coater and a die coater. Among these, a roll knife coater and a die coater are preferable in that the control of the applied thickness is relatively easy. In the case of a roll knife coater, the gap between the back-up roll and the knife roll can be made uniform by making the gap and the die inner pressure of the die inlet at the die coater constant.

As the solution containing the thermoplastic elastomer, any of a solution produced by a solution polymerization method and a solution obtained by dissolving a solid resin produced by bulk polymerization in a solvent may be used.

The resin produced by this bulk polymerization may be a solvent in which a thermoplastic elastomer such as toluene, N, N-dimethylformamide (DMF), methyl ethyl ketone (MEK), dimethylacetamide (DMAc) To obtain a solution.

The thermoplastic elastomer is not particularly limited and may be appropriately selected depending on the purpose. Examples of the thermoplastic elastomer include urethane, polyester, polyamide, olefin and styrene. They may be used alone or in combination of two or more.

Among these, it is preferable that the change of the storage elastic modulus at 0 to 80 캜 is small.

As the urethane system, for example, urethane-based polyurethane elastomer (TPU) is suitably used. Examples of the ester type in the kind of polyol that can be used in the polymerization of the TPU include polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexamethylene adipate (PHA), poly-3-methyl And polyols such as pentane adipate (PMPA) and polycaprolactone (PCL). Examples of the ether type include polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG).

As the polyester type, for example,

Polyester ether type using polybutylene terephthalate (PBT) as a hard segment, polytetramethylene ether glycol (PTMG) as a soft segment,

Polyester ester type using polybutylene terephthalate (PBT) for hard segment and polybutylene adipate (PBA) for soft segment

May be used alone or in combination of two or more.

Examples of olefins include olefin resins such as polyethylene (PE) and polypropylene (PP), and soft segments such as ethylene propylene rubber (EPM) and ethylene propylene diene rubber (EPDM) , And any known resins may be used singly or in combination of two or more.

Examples of the styrene type resin include styrene-ethylene butylene styrene block copolymer (SEBS), styrene butadiene rubber (SBR), styrene ethylene propylene styrene block copolymer (SEPS), styrene butadiene (SB), styrene block copolymer (SBC) May be used alone or in combination of two or more.

As the polyamide system, for example,

A polyether ester type using nylon 6, nylon 11 and nylon 12 as a hard segment, polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG)

Polyether amide type using polypropylenediamine, polybutylenediamine, etc. for soft segment

May be used alone or in combination of two or more.

In addition to the above-mentioned thermoplastic elastomer, the functional film of the present invention may suitably be used in accordance with the purpose, such as a colorant, a lubricant, an antioxidant, an antistatic agent and the like which can be usually used as an additive. As the additive, a master batch diluted with a polymer or a filler may be used.

The functional film of the present invention may have a single-layer structure or a multi-layer structure. The method of forming the multilayer structure is not particularly limited, and may be multilayered by a commonly known lamination method or the like.

Since the functional film of the present invention is excellent in acoustic characteristics and can provide good sound quality, it can be suitably used for damping material applications such as a vibration system supporting member of a speaker, for example, And the like. In addition to acoustic use, it can be used in various applications requiring thickness precision, such as in the field of precision instruments in general, and requiring less variation in stress at the time of elongation.

[Example]

Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

1. Relationship between Film Thickness and Tensile Stress

A TPU film produced using a solution containing 20.0% by weight of an ester type polyurethane thermoplastic elastomer (TPU), 40% by weight of N-dimethylformamide (DMF) and 40% by weight of methyl ethyl ketone (MEK) 15.0 占 퐉, 17.0 占 퐉, 19.0 占 퐉 and 21.0 占 퐉, and the film was formed into a film using a die coater while maintaining the viscosity at 5,000.0 mPa 占 퐏 and the solution temperature at 23.0 占 폚 constant. At this time, a film was produced in the order of 72.0 占 퐉, 80.0 占 퐉, 94.0 占 퐉 and 100.0 占 퐉 while the thickness of the applied film was kept constant from the thinner the set thickness (see Table 1 above). Further, the film was produced while keeping the liquid pressure constant by making the liquid amount of the solution supplied from the die coater constant.

On the other hand, a die coater is used to set the thicknesses of 17.0 mu m and 19.0 mu m for the same TPU sample, respectively. However, without controlling to keep the solid content, the solution temperature, Respectively.

For each of the obtained films, the hardness, the elastic modulus, the average value of the film thickness, the maximum value, the minimum value and the tolerance, the stress variation at the time of 5% elongation and the tensile elongation (N / 20 mm) were measured.

Here, the purpose of the measurement is to evaluate the variation of the thickness for each component, but as described above, since the stress variation (stiffness) also remarkably increases as the thickness increases, the stress variation at the time of elongation is more accurate . In addition, regarding the hardness and the modulus of elasticity, a specific value of the material was obtained, and therefore, the sample was measured for identification.

These results are shown in Table 2. In addition, the hardness was 91 A and the modulus of elasticity was 29.0 MPa in all cases.

The hardness, the elastic modulus, the viscosity, the film thickness, and the stress at the elongation were measured as follows.

Hardness: Measured according to JIS K6253 using a durometer (spring type rubber hardness meter).

Modulus of elasticity: The dynamic viscoelasticity measurement device &quot; Q800 &quot;, manufactured by T.A. Instrument, Japan K.K., was used and measured in accordance with JIS K7244-4 under an environment of 25 占 폚.

Viscosity: Measured according to JIS Z7117-1 using "Viscometer BII type viscometer" manufactured by Toki Sangyo K.K.

Film Thickness: Thirty places were randomly measured in a 1 m 占 1 m film obtained in accordance with JIS Z1072 using a film thickness gauge &quot; dial gauge 0.001 mm &quot; manufactured by Ozaki Seisakusho. Among them, the difference between the maximum value and the minimum value is defined as the maximum value, the minimum value is the minimum value, the average value is obtained by dividing each measured value by 30, and the difference between the maximum value and the minimum value.

Stress variation at the time of elongation: Using a precision universal testing machine &quot; Autograph AG-500NX &quot; manufactured by Shimadzu Seisakusho, based on JIS K7127, the above-mentioned 1 m x 1 m film was randomly measured at five places , And the difference between the maximum value and the minimum value of these values is called a variation value. The smaller the variation value, the more stable sound quality can be obtained and the more excellent the acoustic characteristic can be.

As can be seen from Tables 1 and 2, in the film of the present invention produced by controlling various conditions such as solid content and viscosity by the coating method, a thickness of less than 1 mu m and a very small thickness unevenness and a uniform thickness was obtained. Also, the stress variation at the time of elongation is suppressed to at least about 0 and at most 20% within the range of at least about 0 and 10% elongation at the time of 5% elongation, and when it is used as a vibration damper of a speaker or the like, The sound quality can be provided, and the acoustic characteristics can be stabilized.

On the other hand, in the conventional film produced without controlling various conditions, the tolerance is greatly exceeded by 2 mu m, the stress variation at the time of elongation is 0.05 N / 20 mm or more at 5% elongation, 0.1 N / 20 mm or more, a maximum fluctuation width of 20% or more at any elongation, and it was found that it was difficult to obtain stable sound quality.

From these, it was found that, in order to provide the film with excellent acoustic characteristics, it is necessary to make the thickness unevenness to be very small within 2 탆.

Subsequently, as shown in Table 3, the viscosity and the applied film thickness of the solution containing 10 to 50% by weight (solid content) of the ether type TPU having different hardness and elastic modulus were adjusted to the set thickness, A film was produced in the same manner as the above-mentioned ester type TPU while keeping various conditions at the time of construction constant. The hardness and the modulus of elasticity shown in Table 3 are speculative values after fabrication before fabrication.

For each of the obtained films, the hardness, the elastic modulus, the average value of the film thickness, the maximum value, the minimum value and the tolerance, the stress variation at the time of 5% elongation and the tensile elongation (N / 20 mm) were measured. The results are shown in Table 4. The measurement method of each indicator is also the same as that of the above-mentioned ester type TPU.

As can be seen from Tables 3 and 4, even when a film was produced using an ester type TPU, the tolerance was suppressed to 1 μm or less by controlling various conditions such as solid content and viscosity by a coating method. Also, the stress variation at the time of elongation is suppressed to at least 0.01 N / 20 mm at 5% elongation, at least 0.04 N / 20 mm elongation at 10% elongation, and within 10% It was found to be stable.

Thus, by appropriately controlling various conditions such as the solid content and the viscosity by the coating method, it is possible to suppress the fluctuation of the stress at the time of elongation by making the thickness unevenness to be a film of 2 탆 or less even in the case of different types of thermoplastic elastomers, And it was found that excellent results were obtained.

2. Verification of storage modulus

In order to say that the acoustic characteristics are good, it is required that the variation of the storage elastic modulus in the living environment is also small. Therefore, a film is prepared from a plurality of samples of ester type and ether type of TPU, and polyester by controlling the solid content, viscosity and the like as described above, and the hardness and the storage modulus at 0 to 80 ° C Were measured. The results are shown in Table 5 for the values at 0 deg. C, 25 deg. C and 80 deg. C, and for the variation values which are the difference between the maximum value and the minimum value, the TPR ester type thermosensitive temperature change is shown in Fig. And the light temperature change of the polyester is shown in Fig. 3, respectively. It was also confirmed that the tolerance of all of the obtained films was within 2 占 퐉 and the variation of the stress at the time of elongation was extremely small in these samples.

The hardness of the film produced from each sample was measured by the method described previously and the storage modulus was measured in the same manner except that the measurement temperature was changed.

From the results shown in Table 5 and Figs. 1 to 3, it was found that the variation of the storage elastic modulus due to the light temperature was small in the film of any sample, and excellent acoustic characteristics were obtained. It was also found that the variation of the storage elastic modulus was small as the hardness was low in any type.

Although the embodiments and examples of the present invention have been described in detail above, the functional films of the present invention are not limited to the above-described embodiments, and may include all technical ideas assumed within the range.

The present invention can be applied to various applications requiring thickness precision such as vibration generators of loudspeakers, vibration damping materials of speakers, and the like in the field of precision instruments, as well as requiring less variation in stress at the time of elongation.

Claims (8)

A thermoplastic elastomer composition comprising a thermoplastic elastomer having a thickness of 10 to 100 mu m and a tolerance of 2 mu m or less. The method according to claim 1,
The solid content and the coating thickness of the thermoplastic elastomer in the solution containing the thermoplastic elastomer are kept constant by the coating method and the temperature of the solution is adjusted to 10 to 40 占 폚 and the viscosity is in the range of 100 to 50,000 mPa 占 퐏 The functional film being formed into a film. 3. The method of claim 2,
Wherein the solution comprises 10 to 50 wt% of the thermoplastic elastomer. 4. The method according to any one of claims 1 to 3,
Wherein the thermoplastic elastomer is at least one of a urethane type, a polyester type, a polyamide type, an olefin type and a styrene type. 4. The method according to any one of claims 1 to 3,
Wherein the thermoplastic elastomer is a polyurethane elastomer (TPU). 4. The method according to any one of claims 1 to 3,
A functional film used for a vibration-meter supporting member of a speaker. 5. The method of claim 4,
A functional film used for a vibration-meter supporting member of a speaker. 6. The method of claim 5,
A functional film used for a vibration-meter supporting member of a speaker.

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