CN105866867B

CN105866867B - white reflective film

Info

Publication number: CN105866867B
Application number: CN201610413037.6A
Authority: CN
Inventors: 小野光正; 仓垣雅弘; 楠目博
Original assignee: Teijin DuPont Films Japan Ltd
Current assignee: Toyobo Film Solutions Ltd
Priority date: 2012-08-03
Filing date: 2013-08-02
Publication date: 2017-10-31
Anticipated expiration: 2033-08-02
Also published as: CN105866867A; KR20140122715A; CN104603647B; CN105866866A; TWI595271B; TWI632403B; TW201809737A; TWI632402B; TW201418790A; CN104603647A; TW201809738A; WO2014021476A1; KR101524992B1

Abstract

A kind of white reflective film, the white reflective film forms the outermost support layer B of side comprising reflecting layer A and at least, the support layer B is formed by thermoplastic resin and the inert particle for being dispersed therein and containing, and has the projection caused by above-mentioned inert particle on the surface for forming outermost support layer B side opposite with reflecting layer A.The film can fully suppress the stickup with light guide plate, at the same time, suppress the damage of light guide plate, suppress particle and come off.In addition, can also produce the advantage that：Even if reclaiming film, it is used as preparing film from recovery raw material, the film forming of obtained film is also excellent.

Description

White reflective film

The application is the applying date for August in 2013 2 days, Application No. 201380022733.9, entitled " white is anti- The divisional application of the application for a patent for invention of penetrating property film ".

Technical field

The present invention relates to white reflective film.More particularly to it is used for the white reflective film of liquid crystal display device.

Background technology

The back light unit of liquid crystal display device (LCD) has directly-below type and sidelight (edge light) type, and the directly-below type exists The back side of liquid crystal display panel possesses light source, and then possesses reflectance coating in light source back surface；The side light type is in liquid crystal display panel Back side configuration overleaf possess the light guide plate of reflecting plate, possess light source in the side of such light guide plate.In the past, as The back light unit of large LCD, it is main using just from the viewpoint of the excellent in uniformity of the brightness in the brightness and picture of picture Mo(u)ld bottom half (predominantly directly-below type CCFL), side light type is usually used in the more small-sized LCD such as notebook type PC, but in recent years due to light source, The development of light guide plate, the uniformity of the lightness in side light type backlight unit in brightness and picture is also improved, not only In more small-sized equipment, also begin to use side light type backlight unit in large LCD.In addition, the reason is that thus also having LCD advantage can be thinned.

In side light type backlight unit, the structure that light guide plate is directly contacted with reflectance coating is formed.Therefore, in such structure In, if light guide plate and reflectance coating are pasted, the brightness for the part pasted becomes abnormal, there is asking for deviation in the face for producing brightness Topic.Accordingly, it would be desirable to which there is gap (gap) between light guide plate and reflectance coating, and such gap is kept certain.For example, can So that the gap between light guide plate and reflectance coating is kept into certain by having pearl on the surface of reflectance coating, theirs can be prevented Paste.

But, if the light guide plate now formed by softer raw material is contacted with reflectance coating, have because of reflectance coating or surface Pearl and the problem of damage light guide plate.It is used as its countermeasure, such as Japanese Unexamined Patent Publication 2003-92018 publications, Japanese Unexamined Patent Application Publication 2008- No. 512719 publications like that, there is the report for the reflective sheet for possessing the antisitic defect layer using elastomer class pearl.

But, if making as above-mentioned Japanese Unexamined Patent Publication 2003-92018 publications, Japanese Unexamined Patent Application Publication 2008-512719 publications With soft pearl, although can then suppress the damage of light guide plate, can not reach it is required in recent years ensure gap, if for example applying Larger stress, then possibly can not ensure gap, it is impossible to suppress to paste.For it is such ensure gap the problem of, as pearl, examine Consider using high pearls of the hardness such as inorganic particulate or the organic filler with cross-linked structure such as true spherical silicon dioxides, but they can not Suppress the damage of light guide plate.In addition, using the high pearl of such hardness（The pearl, which has fully to reach, ensures the journey in gap The size of degree）When, the present inventor's new discovery simultaneously pays close attention to problems with：The film of product is not formed in recovery, is used as from recovery In the case that raw material prepares new film again, remain in the pearl reclaimed in raw material and be mixed into film, be particularly in reflecting layer, thus film Multiple, the film forming step-down of film is ruptured, substantially can not be from recovery.

The content of the invention

Therefore, it is an object of the present invention to provide a kind of recyclable white reflective film, the white reflective film can Fully suppress the damage of light guide plate, at the same time, even if reclaiming film and being used as preparing film from recovery raw material, obtained film Film forming is also excellent.

The other other objects and advantages of the present invention can be clear and definite by following explanation.

According to the present invention, above object and advantages of the invention can be reached by a kind of white reflective film, the white Reflective membrane includes reflecting layer A and support layer B, the support layer B thermoplastic resin containing agglutination particle in thermoplastic resin Oil/fat composition is formed, and the primary particle size (dp) of the agglutination particle is less than 3 μm, and aggregate particle size (ds) is less than 8 μm, to support On the basis of layer B volume, the content in support layer B is below the volume % of more than 1 volume % 50,

The outermost layer of at least side of support layer B formation white reflective films, form the outermost support layer B with it is anti- 10 mean roughness (Rz) for penetrating the surface of the opposite sides of layer A meet following formula (1),

The aggregate particle size (ds) of agglutination particle in support layer B meets following formula (2) with support layer B thickness (t)：

0.1×ds(μm)≤Rz(μm)≤0.7×ds(μm)···(1)

0.07≤ds(μm)/t(μm)≤20···(2)。

According to the white reflective film of the feature with above-mentioned a, (hereinafter referred to as white reflective film a), can successfully reach Above-mentioned 1st purpose of the present invention；According to the white reflective film of the invention of the feature with above-mentioned b, (hereinafter referred to as white is anti- Penetrating property film b), can successfully reach above-mentioned 2nd purpose of the present invention.

Brief description of the drawings

Fig. 1 be show the present invention light guide plate Damage Evaluation and particle come off evaluation method schematic diagram.

Fig. 2 is the schematic diagram for showing the structure that the adhesion plaque (adherence spot) for the present invention is evaluated.

Fig. 3 is the photo of an example in the section for showing the projection of the present invention.

The best mode carried out an invention

In the white reflective film of the present invention, no matter white reflective film a or white reflective film b, is respectively provided with reflection Layer A and support layer B.

Each constituent for constituting the present invention is illustrated in detail below.

First, white reflective membrane a is illustrated.

[reflecting layer A]

The present invention reflecting layer A be to be formed by thermoplastic resin and void initiating agent, by containing void initiating agent Contain space in layer so that the layer of white is presented.As such void initiating agent, details are described later, for example, nothing can be used Machine particle, the resin incompatible with constituting reflecting layer A thermoplastic resin (have the situation of referred to as incompatible resin below.). In addition, reflectivity of the reflecting layer A under 550nm wavelength is preferably more than 95%, more preferably more than 96%, particularly preferably More than 97%.Thus become that white reflective film a reflectivity easily is set into preferred scope.

As described above, reflecting layer A has space, the volume institute of the volume relative to reflecting layer A in such space in layer The ratio (voidage rate) accounted for is preferably in the range of 15 ~ 70 volume %.By being set to such scope, reflectivity can be made Improve effect to uprise, become to be easy to get to reflectivity as described above.In addition, can uprise the raising effect of film forming.In space In the case that volume fraction is too low, the trend in distress for obtaining preferred reflectivity.From such a viewpoint, reflecting layer A space The lower limit of volume fraction is more preferably 30 volume %, particularly preferably 40 volume %.On the other hand, in the case of too high, have The trend of the raising effect step-down of film forming.From such a viewpoint, the upper limit of reflecting layer A voidage rate is further excellent Elect 65 volume %, particularly preferably 60 volume % as.

Voidage rate can be reached by the species, size, amount of the void initiating agent for adjusting reflecting layer A.

(thermoplastic resin)

As the thermoplastic resin for constituting reflecting layer A, for example, it can include by polyester, polyolefin, polystyrene, acrylic acid The thermoplastic resin of resin (acryl) formation.Wherein, from the white reflective film for obtaining mechanical property and excellent heat stability Viewpoint is set out, preferably polyester.

As such polyester, the polyester formed by dicarboxylic acid component and diol component is preferably used.It is used as the dicarboxylic acids Composition, can be included from terephthalic acid (TPA), M-phthalic acid, NDA, 4,4 '-biphenyl dicarboxylic acid, adipic acid, The composition of decanedioic acid etc..As diol component, can include from ethylene glycol, BDO, 1,4-CHDM, The composition of 1,6-HD etc..In these polyester, preferably aromatic polyester, particularly preferred polyethylene terephthalate.Though Right polyethylene terephthalate can be homopolymer, but make stretching from film is suppressed into crystallization when uniaxially or biaxially stretching Property, film forming become good aspect and set out, preferred copolymer.As copolymer composition, above-mentioned dicarboxylic acid component, two can be included Alcohol composition, but from heat resistance and film forming and from the viewpoint of depositing, preferably M-phthalic acid, NDA.With polyester On the basis of all 100 moles of % of dicarboxylic acid component, the ratio of copolymer composition is, for example, 1 ~ 20 mole of %, preferably 2 ~ 18 moles %, is entered One step is preferably 3 ~ 15 moles of %, particularly preferably 7 ~ 11 moles %.By the way that the ratio of copolymer composition is set into the scope, film forming Raising excellent effect.In addition, thermal dimensional stability is excellent.

(void initiating agent)

In the A of reflecting layer, in the case where using inorganic particulate as void initiating agent, as inorganic particulate, preferably in vain Color inorganic particulate.As the white inorganic particle, can example go out the particle of barium sulfate, titanium dioxide, silica, calcium carbonate. As long as these inorganic particulates select average grain diameter and content white reflective film is had appropriate reflectivity, their nothings Particular determination.As long as it is preferred that making reflecting layer A, the reflectivity of white reflective film be changed into preferred scope of the invention.In addition, As long as making reflecting layer A voidage rate be changed into the preferred scope of the present invention.In view of these situations, inorganic particulate it is flat Equal particle diameter is, for example, 0.2 ~ 3.0 μm, preferably 0.3 ~ 2.5 μm, more preferably 0.4 ~ 2.0 μm.In addition, with reflecting layer A's On the basis of quality, content preferably 20 ~ 60 the mass %, most preferably further preferred 25 ~ 55 mass %, 31 ~ 53 matter of inorganic particulate Measure %.In addition, by using particle shape as described above, can moderately disperse in the polyester, the aggegation hardly possible of particle occurs, can The film without thick projection is obtained, in addition, can also suppress rupture when oversize grain turns into the stretching of starting point simultaneously.Inorganic particulate can For arbitrary shape of particle, for example, can be tabular, spherical.Inorganic particulate can also carry out improving the surface treatment of dispersiveness.

In the case where using incompatible resin as void initiating agent, as incompatible resin, if the heat with constituting layer Plastic resin is incompatible, then is not particularly limited.For example, in the case where such thermoplastic resin is polyester, preferred polyolefm, Polystyrene etc..They can be the form of particle.As long as in addition, its content selects average grain in the same manner as the situation of inorganic particulate Footpath, content make white reflective film have appropriate reflectivity, and they are not particularly limited.As long as it is preferred that make reflecting layer A, The reflectivity of white reflective film is changed into the preferred scope of the present invention.As long as in addition, becoming reflecting layer A voidage rate For the preferred scope of the present invention.In view of these situations, on the basis of reflecting layer A quality, content preferably 10 ~ 50 matter Measure %, further preferred 12 ~ 40 mass %, most preferably 13 ~ 35 mass %.

(other compositions)

As long as the without prejudice to purpose of the present invention, reflecting layer A can contain other compositions, such as ultra-violet absorber, antioxygen Agent, antistatic additive, fluorescent whitening agent, wax, different from particle or resin of void initiating agent etc..

[support layer B]

The support layer B of the present invention is formed by polyester resin, contains inert particle.

(polyester resin)

As the polyester of the polyester resin as support layer B, same with above-mentioned reflecting layer A polyester gather can be included Ester.In these polyester, from the viewpoint of the white reflective film for obtaining mechanical property and excellent heat stability, preferred aromatics Polyester, particularly preferred polyethylene terephthalate.Although polyethylene terephthalate can be homopolymer, from can carry Height suppresses from the viewpoint of the raising effect of guide-lighting dash-board injury, preferred copolymer.As such copolymer composition, it can include State dicarboxylic acid component, diol component, but same from the viewpoint of damage is suppressed, preferably M-phthalic acid, NDA. On the basis of 100 moles of % of all dicarboxylic acid components of polyester, the ratio of copolymer composition is preferably 1 mole of more than %, more preferably 1.5 moles of more than %, more preferably 2 moles more than %, particularly preferably 3 moles more than %.Additionally, it is preferred that for 20 moles of % with Under, more preferably 18 moles below %, more preferably 15 moles below %, particularly preferably 12 moles below %.By by altogether The ratio being polymerized to point is set to more than lower limit, can especially improve the raising effect for suppressing guide-lighting dash-board injury.On the other hand, by being set to Below the upper limit, become the hardness easily because of crystalline orientation etc. with appropriateness, thus can improve the raising effect for suppressing to paste.

(inert particle)

Can be organic inert particle, inorganic inert particle or organo-mineral complexing inertia as support layer B inert particle Particle.

As organic inert particle, for example, it can include styrene resin beads, organic siliconresin particle, acrylic acid tree Fat granule, styrene-acrylic resins particle, divinylbenzene-acryl resin particle, polyester resin particle, polyimides The macromolecule resin particles such as resin particle, melmac particle.Wherein, have especially in order to ensure gap from easy formed From the viewpoint of the projection of the hardness of appropriateness, particularly preferred organic siliconresin particle, acrylic resin particle.

In addition, as inorganic inert particle, (1) silica (comprising hydrate, silica sand, quartz etc.), (2) can be included The aluminum oxide of various crystal habits, the SiO of (3) containing more than 30 mass %₂Silicate (such as noncrystalline or crystalline of composition Clay mineral, aluminosilicate (include calcined material, hydrate), chrysotile, zircon, flyash (fly ash) etc.), (4) Mg, Zn, Zr and Ti oxide, (5) Ca and Ba sulfate, (6) Li, Ba and Ca phosphate (include monohydric salt, dihydro Salt), (7) Li, Na and K benzoate, (8) Ca, Ba, Zn and Mn terephthalate, (9) Mg, Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, Co and Ni titanate, (10) Ba and Pb chromate, (11) carbon (such as carbon black, graphite), (12) glass Glass (such as glass dust, bead), (13) Ca and Mg carbonate, (14) fluorite, (15) spinel oxides etc..Its In, formed from easy from the viewpoint of the projection in order to ensure gap with especially appropriate hardness, preferably silicon dioxide granule, Particularly preferred aggegation silicon dioxide granule.

In addition, in the present invention, being used as inert particle, it is possible to use the inorganic particulate that is such as coated to by organic matter, by inorganic Organo-mineral complexing inert particle as the coated organic filler of thing.Specifically, as organo-mineral complexing particle, for example Following particle can be included：As having the high score of the organo-metallic compound base as silyl alkyl in side chain or end Son and the inorganic compound composition as silica by covalent bond it is compound obtained by organic-inorganic mixing material formed Particle；It is fusible coated just like grain obtained by organic polymer particulate as crosslinked polystyrene in inert inorganic particle surface Son；Or it is coated just like particle obtained by inert inorganic particulate as aluminum oxide in the adhesion of inertia organic polymer particle surface Deng.

In the present invention, from the viewpoint of the more excellent effect of easy performance, it is used as the preferred inorganic particulate of inert particle.It is special It is not, when using inorganic inert particle as inert particle, inorganic inert particle to be typically due to firmly, so easily being made to light guide plate Into damage, thus it is particularly useful using the present invention.

In order to suppress to paste, as long as average grain diameter and the content selection of support layer B inert particle such as meet at following 10 points Scope as mean roughness Rz or projection frequency.

For example, from the interval holding of light guide plate and film is certain, easily suppressing from the viewpoint of their stickups, average grain diameter is excellent Elect 2 μm ~ 100 μm as.If average grain diameter is too small, Rz has the trend diminished, has white reflective film partly to adhere to leaded light The trend that the possibility of plate is uprised.From such a viewpoint, the lower limit of average grain diameter is preferably 5 μm, more preferably 10 μm, particularly preferably 15 μm.On the other hand, in the case of excessive, particle becomes caducous trend, if occurring de- Fall, then white-spot defects are formed in back light unit.From such a viewpoint, the higher limit of average grain diameter is preferably 80 μm, is entered One step is preferably 75 μm, particularly preferably 70 μm, most preferably 65 μm.

In addition, for example on the basis of support layer B volume, content is preferably the volume % of 0.1 volume % ~ 20.If very few, have Ensure the trend of the raising effect step-down in gap.Therefore, lower limit is more preferably 0.2 volume %, particularly preferably 0.3 body Product %.On the other hand, if excessively, there is the trend for suppressing the raising effect step-down that particle comes off.Therefore, higher limit is further excellent Elect 15 volume %, particularly preferably 12 volume % as.

(other compositions)

In the range of the without prejudice to purpose of the present invention, support layer B can contain the composition beyond above-mentioned constituent.As Such composition, can for example include ultra-violet absorber, antioxidant, antistatic additive, fluorescent whitening agent, wax, different from upper State particle or resin of inert particle etc..

In addition, support layer B, by being set to such form, be able to can be improved containing the void initiating agent enumerated in the A of reflecting layer The raising effect of reflectivity.If conversely, make the content of support layer B void initiating agent reduce or not contain void initiating agent, Can uprise the raising effect of film forming.From these viewpoints, the support layer B voidage rate (body in support layer B space The ratio of volume of the product relative to support layer B) it is preferably 0 volume % ~ be less than 15 volume %, more preferably 0 ~ 5 volume %, it is special You Xuanwei not 0 ~ 3 volume %.Particularly in the present invention, due to the raising effect of reflection characteristic and draftability, institute can be played simultaneously With particularly preferably simultaneously using above-mentioned reflecting layer A preferred voidage rate and the preferred voidage of the support layer B Rate.

(support layer B form)

In the present invention, formed and the support layer B containing inert particle as described above by polyester resin as described above Form the outermost layer of at least side of white reflective film.Moreover, formed such outermost support layer B's and reflecting layer There is the projection formed by above-mentioned inert particle on the surface of the opposite sides of A.In addition, the projection is by constituting the poly- of support layer B The structure of the resin-coated above-mentioned inert particle of ester.

When polyester resin is coated to inert particle, thickness is coated in the range of 50nm ~ 10 μm.Herein, coated thickness is Refer to the thickness of the apex polyester resin of projection.Due to coated thickness within the above range, the damage of light guide plate can be suppressed.Separately Outside so that projection has the hardness of appropriateness, thus can ensure that gap, it can suppress to paste.If coated thickness is excessively thin, do not simply fail to Suppress the damage of light guide plate, and have the possibility for causing particle to come off because of friction.In addition, becoming difficulty ensures gap.It is another Aspect, the blocked up deep inside for causing the particle for forming the projection to be present in support layer B of coated thickness, thus there is shape for lugs It is changed into the possibility of big " gentle " shape of curvature, so as to be difficult to prevent the stickup with light guide plate.From these viewpoints, projection The inert particle lower limit preferably 200nm of coated thickness that is formed by polyester resin, more preferably 1 μm；In addition, higher limit Preferably 8 μm, more preferably 7.5 μm.

So, due in the white reflective film of the present invention, having in the outermost layer of white reflective film and passing through polyester tree Fat is coated to the projection of the structure of inert particle with specific coated thickness, thus, is being connected with light guide plate in use, can suppress because being somebody's turn to do Projection and damage light guide plate.Come off in addition, particle can be suppressed.In addition, it can be ensured that gap.It should be noted that, now make possess this The surface of the side of the projection of sample is light guide plate side.

In addition, from the viewpoint of the gap for ensuring light guide plate and reflectance coating, form outermost support layer B with it is anti- The surface of the opposite sides of layer A is penetrated, above-mentioned projection needs the height with appropriateness, and exists with the frequency of appropriateness.

The height of projection is following height：Surface in the side opposite with reflecting layer A for forming outermost support layer B, ten Point mean roughness (Rz) is 5 ~ 100 μm.By this highly with following projection frequencies, the gap with light guide plate can be substantially ensured that, Paste inhibition excellent.If Rz is too small, inhibition is pasted poor.On the other hand, if Rz is excessive, particle, which comes off, suppresses effect It is really poor.From these viewpoints, Rz lower limit is preferably 7 μm, more preferably 10 μm；In addition, higher limit is preferably 75 μm, more Preferably 50 μm.It should be noted that, such Rz form is mainly obtained by above-mentioned projection.If the reason is that by not The projection for possessing above-mentioned projection form forms main high projection, then cannot get the injury inhibitory effect of light guide plate.

In addition, the frequency that height is more than 5 μm of projection is to form the opposite with reflecting layer A of outermost support layer B The surface of side, the number of per unit area is 10⁶~10¹⁰Individual/m².By the frequency and above-mentioned Rz, it can substantially ensure that and light guide plate Gap, paste inhibition it is excellent.If projection frequency is very few, inhibition is pasted poor.On the other hand, if projection frequency mistake It is many, then the trend that the probability for having particle to come off is improved or reflectivity is reduced.From these viewpoints, the lower limit of projection frequency is excellent Elect 10 as⁷Individual/m², more preferably 5 × 10⁷Individual/m²；In addition, higher limit is preferably 2 × 10⁹Individual/m², more preferably 5 × 10⁸Individual/ m²。

In addition, the damage in order to further suppress light guide plate, also easily ensures enough when light guide plate is crimped with reflectance coating Gap, and further prevent that particle from coming off from film surface and be changed into foreign matter, the mesh that display quality is reduced by screen defect , above-mentioned projection preferred hardness is 10⁰~10³。

If hardness is really up to the mark, there is the trend that damage is easily caused to light guide plate.On the other hand, if excessively soft, having ensures gap Effect step-down trend, or have and suppress the trend of effect step-down that particle comes off.From such a viewpoint, projection hardness The preferred value of lower limit is 5, more preferably 10；In addition, higher limit is more preferably 500, more preferably 200.

Above-mentioned projection hardness can be represented with values below：Based on JIS Z2244, with microhardness testers (such as Elionix Inc. ENT-1100a processed) value that determines.Berkovich (バー U PVC ッチ can be used) pressure head (positive the three of angle=115 ° between rib Pyramidal front end), it will be pressed into load (P) and be set to 500mgf (about 4.9mN), according to the maximum compression distance (h [μm]) of measure Value, hardness (H) is calculated by following formula.

H=0.038×P/h²

(selection height is that the method for more than 5 μm of projection is preferred to the projection that measure preferred pair is randomly selected from sample One kind of determination method), for example such as more than 30 points of multiple projections are carried out, using their average value as projection hardness.Separately Outside, the height of projection can be confirmed by laser microscope.

[Rotating fields]

The reflecting layer A of present invention thickness is preferably 80 ~ 300 μm.The raising effect of reflectivity can thus uprised.If crossing Thin, then the raising effect of reflectivity is low；On the other hand, blocked up then efficiency is low.From such a viewpoint, more preferably 150~250μm。

In addition, support layer B thickness (is be formed into light guide plate side outermost 1 layer with the case of multiple Thickness) be preferably 10 ~ 70 μm.Thus, with the combination of shape and state of above-mentioned preferred inert particle, preferred Rz and projection are easily set to The form of frequency, easily ensures the gap with light guide plate.In addition, can become the raising effect of reflectivity and the raising effect of draftability It is high.If excessively thin, hardly possible reach preferred Rz, have particle come off inhibition reduction trend.In addition, the raising for having draftability is imitated The trend of fruit step-down.On the other hand, if blocked up, there is the trend of the raising effect step-down of reflectivity, and in distress obtain preferred Rz and projection frequency trend.From such a viewpoint, the lower limit of thickness is more preferably 20 μm；In addition, higher limit More preferably 60 μm.

In the present invention, in order to easily make using the rising height represented by the coated thickness and Rz of above-mentioned inert particle as this hair The average grain diameter (d) of inert particle in scope specified in bright, support layer B preferably meets following with support layer B thickness (t) Formula (2) -1,

0.05≤d(μm)/t(μm)≤20···(2)-1

Following formula (2) -2 is more preferably met,

0.1≤d(μm)/t(μm)≤10···(2)-2

Further preferably meet following formula (2) -3.

0.2≤d(μm)/t(μm)≤2.5···(2)-3。

In the case where the d/t values are too small, become the projection of the difficult enough height of generation, having ensures and the gap of light guide plate Improve the trend of effect step-down；On the other hand, in the case of excessive, there is coated thickness to become easy not enough trend, there is suppression The trend for the raising effect step-down that particle comes off.From these viewpoints, the lower limit of above-mentioned ratio is particularly preferably 0.5, enters One step is preferably 0.6；In addition, higher limit is particularly preferably 2.0, more preferably 1.8.

When reflecting layer A to be expressed as A, support layer B is expressed as into B, the stepped construction of white reflective film can be included B is at least configured at outermost the 5 of either side by B/A 2 Rotating fields, B/A/B 3-tier architecture, B/A/B/A 4 Rotating fields Sandwich construction more than layer.Particularly preferably B/A 2 Rotating fields, B/A/B 3-tier architecture.Most preferably the 3 of B/A/B layers knot The problems such as structure, difficult labour life curling.

On reflecting layer A and support layer B, when the overall thickness of white reflective film is calculated as into 100%, preferably reflecting layer A Thickness proportion be 50 ~ 90% and support layer B thickness proportion be 5 ~ 50% so that be 5 ~ 25% form, the flat of each characteristic can be made Weighing apparatus becomes better.Herein, in the case of with multiple each layers, the cumulative thickness that the thickness proportion of each layer refers to them is mutual Ratio.

In the present invention, in addition to reflecting layer A and support layer B, as long as not damaging the purpose of the present invention, there can be others Layer.For example, can have the layer to assign the function such as antistatic behaviour or electric conductivity, ultra-violet resistance.

[characteristic of reflectance coating]

(reflectivity, brightness)

The reflectivity determined from support layer B sides of the white reflective film of the present invention is preferably more than 96%, more preferably More than 97%, more preferably more than 97.5%.Because reflectivity is more than 96%, for liquid crystal display device or illumination etc. In the case of, it can obtain high brightness.Such reflectivity can be by being set to make reflecting layer A voidage rate to become high preferred Form, or by making reflecting layer A thickness thickening or making the thinning grade of support layer B thickness that the form of each layer is set into preferred Form reach.

In addition, the brightness determined from support layer B sides can be tried to achieve by following assay methods, preferably 5400cd/m²More than, enter The preferred 5450cd/m of one step²More than, particularly preferred 5500cd/m²More than.

In white reflective film, with light guide plate in use, above-mentioned reflectivity and brightness are one as light guide plate side The value in the face of side.

(volatile organic solvent amount)

In the white reflective film of the present invention, the volatile organic solvent amount determined with following methods is preferably below 10ppm. Thus, such as in sidelight liquid crystal display can example go out the light guide plate directly contacted with reflectance coating durability improve it is excellent Point.From such a viewpoint, more preferably below 5ppm, preferably more preferably below 3ppm, 0ppm.In this hair In bright, in order that volatile organic solvent quantitative change is few, does not preferably use and applied using the solution of organic solvent in support layer B formation Cloth method, and use following methods.

Then, white reflective membrane b is illustrated.

[reflecting layer A]

Explanation to reflecting layer A can directly apply the described above to white reflective membrane a.That is, to white reflective membrane a Described above also include the explanation of (thermoplastic resin), (void initiating agent) and (other compositions), for white reflective Film b, can directly be applied.

[support layer B]

The support layer B of the present invention is formed by thermoplastic resin, contains agglutination particle.

(thermoplastic resin)

As the thermoplastic resin for constituting support layer B, it can be used same with the thermoplastic resin for constituting above-mentioned reflecting layer A Thermoplastic resin.Wherein, from the viewpoint of the white reflective film for obtaining mechanical property and excellent heat stability, preferred polyester Resin.

As such polyester resin, the polyester same with above-mentioned reflecting layer A polyester can be used.In these polyester, From the viewpoint of the white reflective film for obtaining mechanical property and excellent heat stability, preferred aromatic polyester is particularly preferably poly- Ethylene glycol terephthalate.Although polyethylene terephthalate can be homopolymer, uniaxially or biaxially drawn from by film It can suppress to crystallize and make draftability become good aspect and set out when stretching, preferred copolymer.As such copolymer composition, it can arrange Enumerate above-mentioned dicarboxylic acid component, diol component, but from heat resistance and film forming and from the viewpoint of depositing, preferably M-phthalic acid, 2,6- naphthalenedicarboxylic acids.On the basis of 100 moles of % of all dicarboxylic acid components of polyester, the ratio of copolymer composition is, for example, 1 ~ 20 to rub You are %, preferably 2 ~ 18 moles %, more preferably 3 ~ 17 moles %, particularly preferably 12 ~ 16 moles %.By by copolymer composition Ratio be set to the scope, the raising excellent effect of film forming.In addition, thermal dimensional stability is excellent.

(agglutination particle)

In the present invention, as the particle for the concave-convex surface for forming the stickup to ensure gap, suppression and light guide plate, lead to Cross use present invention provide that agglutination particle so that can carry out film from reclaim, even if using from reclaim raw material prepare film, film Film forming it is still excellent.If thinking the reason is that agglutination particle, then preparing from particle when reclaiming raw material by moderately powder It is broken.

Can be organic agglutination particle or inorganic agglutination particle as support layer B agglutination particle.It is used as organic aggegation grain Son, for example, can include polyester agglutination particle, acrylic resin (acryl) agglutination particle, polyurethane agglutination particle, polyethylene and coagulate Collect particle etc..Wherein, preferred polyester agglutination particle, polyester agglutination particle is considered as not filling even in crushing from recovery process Point, the compatibility with the polyester as primary raw material is still good, and the influence to film forming etc. is limited.As inorganic agglutination particle, Such as can include silica agglutination particle, aluminum oxide agglutination particle, ceramic agglutination particle.If particle is really up to the mark, drawing Stretch easily rupturable during film, film forming is poor, so preferred silica agglutination particle from this viewpoint.

On support layer B agglutination particle, 10 μ are must be over as the aggregate particle size (ds) of the average grain diameter of agglutination particle M and for less than 100 μm.Thus it is the interval holding of light guide plate and film is certain, it can favorably inhibit them and paste, at the same time, Comprising using from the situation for reclaiming raw material, draftability during film forming becomes good.If aggregate particle size is too small, there is white reflective Film becomes easily partly to adhere to the trend of light guide plate.From such a viewpoint, the lower limit of aggregate particle size is preferably 12 μm, More preferably 14 μm, particularly preferably more preferably 15 μm, 16 μm.On the other hand, in the case of excessive, there is draftability The trend of difference, and have the trend of recyclability difference, that is, there is the trend from the film forming difference for reclaiming caudacoria.In addition, there is particle to become easy The trend come off, if falling off, forms white-spot defects in back light unit.From such a viewpoint, aggregate particle size Higher limit is preferably 95 μm, more preferably 90 μm, more preferably 85 μm, particularly preferably 80 μm, most preferably 30 μm.

In addition, the primary particle size (dp) for constituting the primary particle of agglutination particle is preferably more than 0.01 μm, additionally, it is preferred that being Less than 5 μm.By meeting the primary particle size and above-mentioned aggregate particle size scope simultaneously, it can further improve using from when reclaiming raw material Film forming raising effect.If primary particle size is too small, the trend that the intensity for having agglutination particle excessively dies down, therefore obtain foot Enough big aggregate particle sizes become difficult.From such a viewpoint, the lower limit of primary particle size is more preferably 0.02 μm, further Preferably 0.03 μm, particularly preferably 0.05 μm.On the other hand, in the case of excessive, when preparing from recovery raw material Offspring is destroyed, still can the larger particle of remaining particle diameter, have the trend of the raising effect step-down of the film forming after reclaiming. From such a viewpoint, higher limit is more preferably 4 μm, more preferably 3 μm, most preferably particularly preferably 2 μm, 1 μm.

In addition, on the basis of support layer B volume, the content of support layer B agglutination particle is 1 ~ 50 volume %.If very few, Then the concave-convex surface of white reflective film is few, it is impossible to will be certain with the interval holding of light guide plate.Therefore, lower limit is further preferred For 2 volume %, particularly preferably 3 volume %.On the other hand, if excessively, support layer B intensity difference has production energy during film forming The mechanical strength for the film that power deteriorates or obtained becomes not enough trend.In addition, it is many from particle quantitative change when reclaiming, improve the rate of recovery Become difficult, so as problem.Therefore, higher limit is more preferably 45 volume %, particularly preferably 40 volume %.

(other compositions)

Inert particle during this can be illustrated to the explanation of white reflective membrane a above-mentioned (other compositions) replaces with solidifying Collect particle and apply.

(support layer B form)

In the present invention, formed by thermoplastic resin as described above, the support layer B containing agglutination particle as described above Form the outermost layer of at least side of white reflective film.Forming the opposite with reflecting layer A of such outermost support layer B The surface (situation for having referred to as outermost surface below) of side, with the projection formed by above-mentioned agglutination particle.From ensuring leaded light From the viewpoint of the gap of plate and reflectance coating, in outermost surface, such projection needs the height with appropriateness.

Therefore, in the present invention, agglutination particle of 10 mean roughness (Rz) of outermost surface with constituting support layer B Aggregate particle size (ds) need to meet following formula (1).

0.1×ds(μm)≤Rz(μm)≤0.7×ds(μm)···(1)

Due to meeting above-mentioned formula (1), moderately it is buried in support layer in the agglutination particle of outermost surface and moderately Protrusion so that with concave-convex surface, the concave-convex surface has the height of appropriateness, and thus can play excellent ensures the effect in gap Really.In above-mentioned formula, the situation that Rz value is smaller than the value on the left side represents the form that agglutination particle is excessively buried in support layer B, Therefore there is the trend for the effect difference for ensuring gap.From such a viewpoint, preferably meet 0.2 × ds (μm)≤Rz's (μm) Form, more preferably meets 0.3 × ds (μm)≤Rz (μm) form.On the other hand, the Rz value situation bigger than the value on the right Represent that agglutination particle, from support layer B excessively prominent forms, there is the trend of particle deciduous difference when being contacted with light guide plate.From this From the viewpoint of sample, Rz (μm)≤0.6 × ds (μm) form is preferably met, Rz (μm)≤0.5 × ds is more preferably met The form of (μm).

In order to be set to form as described above, as long as considering the aggregate particle size of agglutination particle used, adjustment support layer B's Thickness.For example, in the case of the agglutination particle with certain aggregate particle size, if making support layer B thickness thinning, becoming For Rz value close to the direction of the value on the right, if excessively it is thinning, more than the value on the right.On the other hand, if making support layer B thickness Degree is thickening, then is changed into Rz value close to the direction of the value on the left side, such as excessively thickening, then less than the value on the left side.It is contemplated that such Trend is adjusted.

As the form of the concave-convex surface of outermost surface, from the viewpoint of the gap for ensuring light guide plate and reflectance coating, Preferably appropriate projection frequency.

In outermost surface, the number for being highly the preferred per unit area of projection frequency of more than 5 μm of projection is 10⁶~ 10¹⁰Individual/m².By the projection frequency and above-mentioned Rz, the gap with light guide plate can be more fully ensured, suppress the raising effect pasted It is really excellent.If projection frequency is very few, the raising effect for suppressing to paste is poor.On the other hand, if projection frequency is excessive, there is particle The trend that the probability come off is improved or reflectivity is reduced.

[Rotating fields]

In addition, support layer B thickness (is be formed into light guide plate side outermost 1 layer with the case of multiple Thickness) be preferably 10 ~ 70 μm.Thus, with the combination of shape and state of above-mentioned preferred agglutination particle, easily by the secondary grain of agglutination particle Footpath ds and 10 mean roughness Rz relation are set to preferred form as described above, easily ensure the gap with light guide plate.Separately Outside, Rz and projection frequency form are easily set to above-mentioned preferred form.In addition, the raising effect and draftability of reflectivity can be made Raising effect uprise.If excessively thin, hardly possible reach preferred Rz, have particle come off inhibition reduction trend.In addition, there is drawing The trend of the raising effect step-down of stretching property.On the other hand, if blocked up, there is the trend of the raising effect step-down of reflectivity, and have Seldom arrive the trend of preferred Rz and projection frequency.From such a viewpoint, lower limit is more preferably 20 μm；In addition, Higher limit is more preferably 60 μm.

In the present invention, the thickness (t) of the aggregate particle size (ds) of the agglutination particle in support layer B and support layer B is preferably full Foot column (2) -1 ',

0.05≤ds(μm)/t(μm)≤20···(2)-1’

Following formula (2) -2 ' is more preferably met,

0.1≤ds(μm)/t(μm)≤10···(2)-2’

Further preferably meet following formula (2) -3 '.

0.2≤ds(μm)/t(μm)≤2.5···(2)-3’。

Due to meeting above-mentioned formula, in outermost surface, easily with concave-convex surface, the concave-convex surface has the height of appropriateness Degree, thus can uprise the raising effect for ensuring gap.In above-mentioned formula (2) -1 ', in the ds/t value feelings smaller than the value on the left side Under condition, the trend for thering is agglutination particle to be easily buried in support layer B, the trend for having the raising effect difference for ensuring gap.From such Viewpoint is set out, and lower limit is particularly preferably 0.07≤ds of satisfaction (μm)/t (μm) form, more preferably meets 0.09≤ds (μ M)/t (μm) form, more preferably meets 0.3≤ds (μm)/t (μm) form, particularly preferably meets 0.4≤ds (μm)/t (μm) form.On the other hand, in the case where the value on the ds/t the right of value than above-mentioned formula (2) -1 ' is big, there is aggegation The trend that particle is easily protruded from support layer B, the trend for having the raising effect come off difference when suppressing to contact with light guide plate.From so From the viewpoint of, it is desirable to higher limit particularly preferably meets ds (μm)/t (μm)≤19, more preferably meets ds (μm)/t (μm)≤18, Particularly preferably meet ds (μm)/t (μm)≤2.

In the present invention, in addition to reflecting layer A and support layer B, as long as not damaging the purpose of the present invention, there can be others Layer.For example, can have the layer to assign the function such as antistatic behaviour or electric conductivity, ultra-violet resistance.In addition, particularly passing through When rubbing method or laminating set support layer B, it may also set up to improve the layer of the film forming of the film with reflecting layer A.

[characteristic of reflectance coating]

(reflectivity, brightness)

Related explanation can directly apply the explanation to white reflective membrane a.

(volatile organic solvent amount)

In the white reflective film of the present invention, the volatile organic solvent amount determined with following methods is preferably below 10ppm. Thus, obtaining from raw material is reclaimed, during using it by film film forming, the angry trace (gas mark) of difficult labour, draftability is improved.From so From the viewpoint of, more preferably below 5ppm, more preferably below 3ppm, preferably 0ppm.In the present invention, in order to Make volatile organic solvent quantitative change few, preferably do not use and adopted using the solution coating method of organic solvent in support layer B formation With following methods.

Then, white reflective membrane a and b preparation method are illustrated.

[preparation method of film]

Explanation prepares an example of white reflective the film a or b of present invention method below.

When preparing the white reflective film of the present invention, lead to preferably on the reflecting layer A obtained by extrusion by melting etc. The formation support layer B such as molten resin rubbing method (including melting extrusion resin rubbing method), coetrusion and laminating is crossed, so that shape Into stepped construction.Wherein, white reflective film of the invention particularly preferably by coetrusion by B layers of reflecting layer A and support layer Fold and prepare.Additionally, it is preferred that reflecting layer A and support layer B are directly laminated by coetrusion.By so being entered with coetrusion Row stacking, not only can uprise reflecting layer A and support layer B interface adhesiveness, and need not undergo for by film laminating or Support layer B process will be re-formed after film film forming, thus can inexpensively, easily carry out volume production.

Below to using polyester as the thermoplastic resin and composition support layer B thermoplastic resin for constituting reflecting layer A, adopting Illustrated with coetrusion as the situation of laminating method, but the present invention is not limited to such preparation method, can be with The description below is that the other forms of reference pair are similarly prepared.Now, in the case where not containing extrusion operation, as long as Following " melting extrusion temperature " is replaced with " melting temperature ".It should be noted that, herein by the fusing point of the polyester used It is designated as Tm (units：DEG C), glass transition temperature is designated as Tg (units：℃).

First, as the polymer blend to form reflecting layer A, prepare polyester, void initiating agent and other The composition that meaning composition is mixed.In addition, as the polymer blend to form support layer B, preparing polyester, inertia grain The composition that son and other any conditions are mixed.These polymer blends are dried and fully removes moisture and uses.

Then, dry polymer blend is put into different extruders respectively, carries out melting extrusion.Melting is squeezed Go out temperature and need for more than Tm, as long as being set to Tm+40 DEG C or so.

In addition, the polymer blend, the polymer blend particularly for reflecting layer A that are now used to prepare film preferably use line Footpath is that the non-woven fabric type filter that the average pore size that less than 15 μm of stainless steel filament is made is 10 ~ 100 μm is filtered.Pass through Carry out the filtering, can suppress generally easily aggegation and form the aggegation of the particle of thick agglutination particle, obtain the film of thick few foreign. It should be noted that, the average pore size of non-woven fabrics is preferably 20 ~ 50 μm, more preferably 15 ~ 40 μm.Filtered polyester combination Thing while in the state of melting by using material feeding block (feed block) multilayer extrusion method (coetrusion) with many stratiforms State is extruded from die head, prepares unstretched layer stacks of sheets.The unstretched layer that will be extruded with curtain coating drum (casting drum) by die head Stacks of sheets is cooled and solidified, and non-stretched stacked film is made.

Then, heated by roller, infrared heating etc. heats the non-stretched stacked film, the mechanical direction of principal axis of film forming (with Under have referred to as longitudinal, length direction or MD situation.) stretching obtain longitudinal stretching film.The stretching is preferably by the roller of more than 2 Difference carry out.Film after longitudinal stretching is then directed into stenter, in the side vertical with thickness direction with longitudinal direction To (have below referred to as laterally, width or TD situation.) stretching, biaxially-stretched film is made.

As draft temperature, preferably in more than the Tg of polyester (polyester for preferably comprising reflecting layer A) and less than Tg+30 DEG C Temperature is carried out, and film forming is excellent, and easily preferably forms space.In addition, as stretching ratio, being longitudinally, laterally both preferably 2.5 ~ 4.3 times, more preferably 2.7 ~ 4.2 times.If stretching ratio is too low, the trend that the uneven thickness for having film deteriorates, and Interstitial trend in distress；On the other hand, if too high, there is the trend easily ruptured in film forming.

Herein, in the white reflective film a of present invention preparation, in order to which the shape that suitable inert particle is coated is made State, it is preferred to use highly oriented stretching condition.Highly oriented stretching condition refers to the stretching condition for easily forming high molecularly oriented, for example, make Elongating temperature step-down or the stretching condition for making stretching ratio uprise or combine them.Therefore, it is set in low stretching ratio Low draft temperature condition, on the contrary high stretching ratio is set in high draft temperature, it is preferably set to such combination.

In addition, it is also preferred that using the draw speed of appropriateness.If the reason is that draw speed is excessively slow, thering is resin to become Easily loose trend, is difficult to the trend to form projection so having, there is the thinning trend of coated thickness；If in addition, draw speed mistake It hurry up, then inert particle is easily pressed into the trend in support layer B so having, has coated thickness to become by the trend for having tensile stress to uprise Thick trend.Specifically, as the draw speed of longitudinal direction, particularly preferably preferably 5 ~ 1000%/second, 200 ~ 500%/second. In addition, being used as horizontal draw speed, particularly preferably preferably 0.2 ~ 100%/second, 3 ~ 10%/second.

So, if the preparation method for returning to white reflective the film a or b of the present invention continues to record, longitudinal direction is such as being implemented As stretching and then progress cross directional stretch during successively biaxial drawing, preferably compare the 2nd stage (being in this case cross directional stretch) High 10 ~ 50 DEG C or so of the draft temperature in the 1st stage.The reason is that by being orientated in the stretching in the 1st stage, being used as single shaft The Tg of film rises.

Additionally, it is preferred that film is preheated before being stretched at each time.As long as the pre-heat treatment of such as cross directional stretch is from than polyester (preferably Constitute reflecting layer A polyester) temperature Tg+5 DEG C high start gradually to heat up.The heating of cross directional stretch process can be continuous Or substep (successively), generally in turn heated up.For example the regions of lateral stretch of stenter is divided into along film moving direction many It is individual, heated up in each area by flowing through the heating medium of set point of temperature.

Film after biaxial stretch-formed then implements thermal finalization, hot wire-CVD and handles and Biaxially oriented film is made successively, is squeezed from melting Go out until stretching, these processing can also be carried out while film is moved.

Polyester (can preferably comprised the poly- of reflecting layer A by the film after biaxial stretch-formed in the state of two ends are held with clip Ester) (Tm-20 DEG C) ~ (Tm-100 DEG C) of fusing point when being designated as Tm under, reduced with constant width or less than 10% width and carry out heat Handle and thermal finalization, reduce percent thermal shrinkage.If such heat treatment temperature is too high, the trend that the flatness for having film is deteriorated has Uneven thickness becomes big trend.On the other hand, if too low, percent thermal shrinkage becomes big trend.

In addition, in order to adjust thermal shrinking quantity, the draw rate of film longitudinal direction by two tip cut-offs of the film of holding, can be adjusted, made It is in longitudinal relaxation.It is used as loose method, the speed of the roller group of adjustment tenter outlet side.As loose ratio, relatively In stenter film linear velocity carry out roller group reduction of speed, implement preferably 0.1 ~ 2.5%, further preferred 0.2 ~ 2.3%, particularly preferably 0.3 ~ 2.0% reduction of speed, so as to relax and (be referred to as the value " relaxation rate ") film, longitudinal heat is adjusted by controlling relaxation rate Shrinkage factor.In addition, film laterally untill by two tip cut-offs during width reduce, can obtain desired percent thermal shrinkage.

It should be noted that, when biaxial stretch-formed, in addition to the successively biaxial drawing method of longitudinal direction-transverse direction as described above, Can be horizontal-longitudinal successively biaxial drawing method.In addition, simultaneously biaxial drawing method can be used to carry out film forming.Twin shaft is drawn at the same time It it is, for example, 2.7 ~ 4.3 times, preferably 2.8 ~ 4.2 times in stretching ratio longitudinally, laterally in the case of stretching method.

It so can obtain the white reflective film of the present invention.

Finally, the recovery for preparing closely related film especially pair with the white reflective film b of the present invention is illustrated.

[from the preparation for reclaiming raw material]

In the present invention, the white reflective film that will be obtained can be used by crushing, melting extrusion material bits (chip) change The material obtained makes an addition in film, preferably made an addition in the A of reflecting layer as from raw material is reclaimed, and prepares as described above white anti- Penetrating property film.Now, if the film for reclaiming the origin of raw material as oneself is the white reflective film for possessing the form of the present invention, even if Preparing in the process of film film forming from the process for reclaiming raw material or using it, the agglutination particle in support layer B is being crushed, and makes It contains in freshly prepd film, the reduction that the optical characteristics such as film forming or reflectivity do not occur yet, can obtain good film forming Property.Therefore, as the process for preparing material bits, although have no specifically limited, but mechanism as described above is considered, it is desirable to possess powder Broken mechanism, make containing agglutination particle crush as much as possible.Thus, use from reclaim raw material made again as film raw material Used time, also the influence containing agglutination particle can be made to become smaller, obtain the more excellent white reflective film such as film forming.

When such raw material of recovery certainly is made an addition in film, on the basis of the overall quality of film, 5 ~ 50 matter are preferably set to % is measured, can uprise the raising effect of above-mentioned film forming.In addition, preferred form is while makes an addition to support layer B and reflecting layer Form in A, and substantially without the form made an addition in support layer B in the A of reflecting layer.In this case, with On the basis of reflecting layer A quality, reflecting layer A's is preferably set to 10 ~ 70 mass %, the raising of film forming from the content for reclaiming raw material Effect is more excellent.It should be noted that, although it can also be added into support layer B from recovery raw material, but particularly preferably will be former from reclaiming Expect to be used for reflecting layer A and be substantially not used in support layer B.By the way that such form is made, can not only maintain good film forming, Reflectivity, and can obtain suppressing the superficiality and excellent production capacity with the stickup of light guide plate, it is advantageous to.

Embodiment

Narration is of the invention in detail by the following examples.It should be noted that, each characteristic value is determined using the following method.

(A) it is directed to the assay method of reference example 1 ~ 9, embodiment 2,3,10 ~ 17 and comparative example 1,4

(1) light reflectance

Integrating sphere is installed on spectrophotometer (Shimadzu Seisakusho Ltd. UV-3101PC), being determined under 550nm wavelength will BaSO₄The reflectivity when albedometer of blank is 100%, regard the value as reflectivity.It should be noted that, determine in support layer B The surface of side is carried out.In the case where table, the back of the body have different support layer B, the support layer surface in light guide plate side is measured.

(2) average grain diameter of void initiating agent (inorganic particulate)

With particle size distribution meter (hole makes made LA-950), the size distribution of particle is tried to achieve, by d₅₀Particle diameter as flat Equal particle diameter.

(3) volatile organic solvent amount

Under room temperature (23 DEG C), 1g membrane sample is put into 10L fluororesin bag, will wherein be purged simultaneously with purity nitrogen Sealing.Then, immediately with the flow of 0.2/ minute respectively from the nitrogen of nitrogen collection 0.2L, 1.0L in such bag to 2 analyses With in TENAX-TA trap tubes, using them, by HPLC and GCMS, to Elements in Organic Solvents contained in the nitrogen of collection Quality is quantified.Obtained value is scaled the amount in 10L nitrogen, having in trying to achieve the nitrogen for evaporating into 10L from 1g membrane sample The quality of machine solvent, is used as volatile organic solvent amount (unit：Ppm, on the basis of the quality of membrane sample).It should be noted that, close In aldehydes, with acetonitrile by aldehyde derivatives from trap tube dissolution, and quantified by HPLC.In addition, in HPLC and GCMS value In the case of difference, using the value of one side of more detection.

It should be noted that, it is below 10ppm's by volatile organic solvent amount for embodiment 10 ~ 17 and comparative example 5 ~ 11 Situation is evaluated as zero, the situation more than 10ppm is evaluated as ×.

(4) film thickness and Rotating fields

White reflective film is cut into slices with slicer, exposing for section is carried out, Hitachi's S-4700 types are used Emission type SEM is observed under 500 times of multiplying power to such section, and film entirety, reflecting layer are tried to achieve respectively A, support layer B thickness.It should be noted that, overall and support layer B the thickness of film is set to eliminate agglutination particle or inert particle Thickness from the part for the part for supporting layer surface protrusion.The thickness ratio of each layer is calculated afterwards in the thickness (μm) for trying to achieve each layer.

(5) calculating of voidage rate

Polymer, addition particle, the density of other each compositions and the Blend proportion of the layer as requested for obtaining space volume fraction Example tries to achieve calculating density.Meanwhile, the layer peel off etc. to separate, quality measurement and volume, calculate actual according to them Density, is tried to achieve according to calculating density and actual density by following formula.

Voidage rate=100 × (1- (actual density/calculating density))

It should be noted that, the density of M-phthalic acid copolymerization polyethylene terephthalate (after biaxial stretch-formed) is set to 1.39g/cm³, the density of barium sulfate is set to 4.5g/cm³。

In addition, the only layer of separation determination voidage rate, tries to achieve the quality of per unit volume to try to achieve actual density.Just For volume, sample is cut into 3cm²Area, will with electronic gauge (Anritsu (ア Application リ Star) K-402B processed) measure 10 Average value is calculated as thickness with area × thickness obtained by thickness under the size of individual point.Quality electronic balance Weighed.

It should be noted that, as the proportion of agglutination particle, use the value for the bulk specific gravity tried to achieve with following graduated cylinder method.To Volume determines overall weight, by the overall weight to fill the agglutination particle of absolute dry condition in 1000ml graduated cylinder The weight of graduated cylinder is subtracted so as to try to achieve the weight of the agglutination particle, the volume of the graduated cylinder is determined, by using the weight of the agglutination particle Measure (g) divided by the volume (cm³) try to achieve.

(6) fusing point, glass transition temperature

Device (DSC of TA Instruments 2100) is determined using Differential Scanning Calorimetry, with 20 DEG C/min of heating speed Degree is measured.

(7) ten mean roughness (Rz)

Device SE-3CKT (strain formula can small slope study made) is determined with three-dimensional roughness, cutoff in 0.25mm, The projection distribution map (profile) on film surface is determined under 1mm measured length, 2 μm of sweep span, the scan stripes number of 100, Projection distribution map is recorded under height multiplying power, 200 times of scanning direction multiplying power at 1000 times.In obtained projection distribution map, 5 points are taken from peak (Hp) high side, a low side takes 5 points from paddy (Hv), and 10 mean roughness are tried to achieve by following formula (Rz, unit：nm).It should be noted that, using three-dimensional roughness resolver SPA-11, (Co., Ltd. little Ban is ground in parsing Study carefully made).

In addition, according to obtained projection distribution map (transverse axis：Rising height, the longitudinal axis：The projection distribution map of projection number), ask Obtain projection number (individual/m that height is more than 5 μm²), it is used as projection frequency.

(8) Damage Evaluation (ploughing evaluation) of light guide plate and the evaluation that comes off of particle

As shown in Figure 1, length 200mm × width 200mm × thickness 3mm is pasted securely in one end of handle portion (1) Iron plate (2, weight is about 200g), thereon, paste to evaluate reflection of the face as width 250mm × length 200mm above Film (3), each 25mm part is stretched out from iron plate (makes the 200mm × 200mm in center part It is overlapping with iron plate).Now, making the evaluation face (support aspect) of reflectance coating turns into outside.In addition, by the width of reflectance coating The unnecessary 25mm in two ends the partially folded dorsal part to iron plate, knife (is inserted in the end for excluding reflectance coating during sampling because of knife etc. The part of sword) scraping light guide plate influence.

Then, will (4, at least 400mm × 200mm size be led by light guide plate above of point face with point (401) Tabula rasa) it is fixed on horizontal desk, the reflectance coating of iron plate that is fixed on produced above is put with facing down to for reflectance coating side Put on light guide plate, evaluation face is contacted with light guide plate, and then in the counterweight (5) for placing 500g thereon, with 200mm distance (so that the mobile reflectance coating for being fixed on iron plate in 400mm × 200mm region) is come and gone with the speed that 1 time comes and goes about 5 ~ 10 seconds It is mobile 15 times.Then, in light guide plate surface, the particle come off using 20 times of magnifying glasses for its scraping situation and from reflectance coating The presence or absence of observed, evaluated according to following benchmark.

In all scopes of rubbed 400mm × 200mm on light guide plate, put after reciprocating 15 times without available Big sem observation to the situation of damage be designated as " non-scraping " (scraping is evaluated as zero), without observable after reciprocating 10 times Damage but " difficult scraping " (scraping is evaluated as △) is designated as reciprocating the situation that has observable damage after 15 times, past The situation that return has observable damage after mobile 10 times is designated as " scraping " (scraping be evaluated as ×).

In addition, after reciprocating 15 times, in all scopes of rubbed 400mm × 200mm on light guide plate, if The white foreign matter that can not be observed with magnifying glass, then be designated as " particle is not fallen off " (come off and be evaluated as zero).In addition, there is observable During the white foreign matter arrived, by white foreign matter as microscopic, if confirming as inert particle (agglutination particle), and come off Particle be less than 5, then be designated as " particle is not almost fallen off " (come off and be evaluated as △), if more than 6, then be designated as " particle Come off " (come off be evaluated as ×).

It should be noted that, when carrying out above-mentioned evaluation, it should strongly suppress the influence of spot size, in light guide plate, strongly select The big region of spot size is selected, is as one man carried out in each evaluation sample.

(9) adhesion plaque evaluation (paste and evaluate)

Casing (6) is taken out from LG company LED liquid crystal television machine (LG42LE5310AKR), is placed on horizontal desk, Make inside television side upward, the reflectance coating of size almost identical with casing is being placed thereon, is making support layer up, Jin Er Light guide plate and 3 optical sheets (diffusion barrier 2,1, prism) (7) that television set possessed originally are placed thereon.Then, exist In its face, in the region of the concavo-convex most violent part comprising casing, place possess three a diameter of 5mm as illustrated in fig. 2 Circular leg equilateral triangle type pedestal (801), thereon further place 15kg counterweight (802), this is observed by visual observation Three leg areas encompassed of sample, if bright part without exception, are designated as " no adhesion plaque " (adhesion plaque is evaluated as zero).Separately Outside, in the case where there is abnormal bright part, the DBEF that television set possessed originally is further placed on 3 optical sheets Sheet material, likewise by being visually observed, if not restoring abnormal bright part, is designated as " having adhesion plaque " and (is evaluated as ×), if there is no abnormal bright part, being designated as " almost without adhesion plaque " (being evaluated as △).It should be noted that, three leg institutes The approximate equilateral triangle that the length that the region surrounded is set to each side is 10cm.

(B) for embodiment 2,3, reference example 1 ~ 9 and comparative example 1,4

(10) primary particle size (dp) of agglutination particle

For the film containing agglutination particle and recovery raw material, using solvent dissolving resin composition, the particle (two thus reclaimed Secondary particle) observed using Hitachi S-4700 type field emission type SEM under 1000 times of multiplying power, see The aggegation situation of the primary particle on offspring surface is examined, particle size determination is carried out to any 100 primary particles, it is average according to it Value tries to achieve primary particle size (dp).

In the above-mentioned methods, agglutination particle is (such as organic in the case of also dissolving when by solvent dissolving resin composition In the case of particle), it is aobvious using Hitachi S-4700 type field emission types scanning electron using the agglutination particle before blending Micro mirror, is observed under 10000 times of multiplying power, the aggegation situation of the primary particle on observation offspring surface, to any 100 Individual primary particle carries out particle size determination, and primary particle size (dp) is tried to achieve according to its average value.

1 μm is designated as less than 3 μm of situation " ＜ 3 ", the situation that will be less than 1 μm is designated as " ＜ 1 ".

(11) aggregate particle size (ds) of agglutination particle

For the film containing agglutination particle and recovery raw material, using solvent dissolving resin composition, the particle (two thus reclaimed Secondary particle) observed using Hitachi S-4700 type field emission type SEM under 1000 times of multiplying power, it is right Any 100 particles carry out particle size determination, and aggregate particle size (ds) is tried to achieve according to its average value.It should be noted that, beyond spherical In the case of tried to achieve by (major diameter+minor axis)/2.Herein, minor axis refers to the maximum gauge with major diameter vertical direction.

In the above-mentioned methods, agglutination particle is (such as organic in the case of also dissolving when by solvent dissolving resin composition In the case of particle), it is aobvious using Hitachi S-4700 type field emission types scanning electron using the agglutination particle before blending Micro mirror, is observed under 1000 times of multiplying power, determines the particle diameter of 100 particles, aggregate particle size is tried to achieve according to its average value (ds).It should be noted that, tried to achieve in the case of with major diameter and minor axis by (major diameter+minor axis)/2.Herein, minor axis refers to and length The maximum gauge of footpath vertical direction.

(12) brightness

Reflectance coating is taken out from LG company LED liquid crystal television machine (LG42LE5310AKR), being arranged at various reflectance coatings (will Support layer side uses luminance meter (big tomb electronics as on picture side (face being connected with light guide plate) in the state of back light unit Model MC-940 processed), under 500mm mensuration distance brightness is determined from front to the center of backlight.

(13) white point evaluation

Using the reflectance coating and light guide plate used in the evaluation of above-mentioned (8), so that support layer is face-up on desk Mode places reflectance coating, thereon to make a little face-down mode place light guide plate, is placed respectively on four sides of light guide plate and solid Fixed each 200g counterweight, using the back light of LG company LED liquid crystal television machine (LG42LE5310AKR), from light guide plate Side incident light, if there is the bright point beyond the light guide plate point that can be observed by visual observation, is designated as generation white point and (is evaluated as ×).On the other hand, if the abnormal bright point that can not be observed by visual observation, is designated as not producing white point (being evaluated as zero).

(14) film forming draftability

The continuous film forming method by using stenter is observed by film forming stability during film film forming described in embodiment, is pressed Evaluated according to following benchmark.

◎：Can stably film forming more than 3 hours.

○：Can stably film forming more than 1 hour.

△：1 cut-out occurred in 1 hour.

×：Repeatedly cut-out occurred within 1 hour, it is impossible to stably film forming.

(C) embodiment 10 ~ 17 and comparative example 5 ~ 11 are directed to

(15) the coated thickness of inert particle

Using slicer, section sample is cut from the film of epoxy resin embedding.Now, note inserting direction etc. of blade with Just projection is not crushed.For the section of section sample, Hitachi S-4700 type field emission type scanning electrons are used Microscope, is observed under 3000 times of multiplying power.

100 particle sections are taken pictures, as shown in figure 3, drawing the horizontal line (a) on film surface in photo, being put down with (a) Row ground by the straight line (b) on projection summit, with the straight line (c) of (a) parallel through the particle topmost in projection, according to (b) (c) thickness (d) of the resin-coated part of measuring space projection apex, the coated thickness using its average value as particle.

Preparation example 1：The synthesis of M-phthalic acid copolymerization polyethylene terephthalate 1

By the dimethyl terephthalate (DMT) of 136.5 mass parts, 13.5 mass parts (relative to obtained polyester it is all acid into Points of 100 moles % are 9 moles of %) DMIP, the ethylene glycol of 98 mass parts, the diethylene glycol (DEG) of 1.0 mass parts, 0.05 The manganese acetate of mass parts, the lithium acetate of 0.012 mass parts are fitted into the flask for possessing rectifying column, distiller condenser, while stirring It is heated to 150 ~ 240 DEG C and distills methanol, carries out ester exchange reaction.After methanol is distilled, the phosphorus of 0.03 mass parts is added The germanium dioxide of sour trimethyl, 0.04 mass parts, reactant is transferred in reactor.Then, while stirring gradually by instead Answer and 292 DEG C are warming up to while 0.3mmHg is decompressed in device, carry out polycondensation reaction, obtain M-phthalic acid copolymerization poly- to benzene two Formic acid glycol ester 1.The fusing point of the polymer is 235 DEG C.

Preparation example 2：The synthesis of M-phthalic acid copolymerization polyethylene terephthalate 2

Dimethyl terephthalate (DMT), 21.0 mass parts for being changed to 129.0 mass parts are (all relative to obtained polyester Sour 100 moles of % of composition are 14 moles of %) DMIP, in addition, between being obtained in the same manner as above-mentioned preparation example 1 Phthalic acid copolymerization polyethylene terephthalate 2.The fusing point of the polymer is 215 DEG C.

Preparation example 3：The synthesis of M-phthalic acid copolymerization polyethylene terephthalate 3

Dimethyl terephthalate (DMT), 7.5 mass parts for being changed to 142.5 mass parts are (all relative to obtained polyester Sour 100 moles of % of composition are 5 moles of %) DMIP, in addition, between being obtained in the same manner as above-mentioned preparation example 1 Phthalic acid copolymerization polyethylene terephthalate 3.The fusing point of the polymer is 245 DEG C.

Preparation example 4：The preparation of organic agglutination particle

Load following described raw material in autoclave, heated 120 minutes in 180 ~ 240 DEG C, carry out ester exchange reaction. Then, reaction system is warming up to 245 DEG C, pressure in system is set to 1 ~ 10mmHg, continue the reaction of 60 minutes, so as to obtain Copolyester.

The mass parts of dimethyl terephthalate (DMT) 134

The mass parts of DMIP 5

The mass parts of 5- sodium sulfonates DMIP 3

The mass parts of p-tert-butyl benzoic acid methyl esters 5

The mass parts of ethylene glycol 136

The mass parts of four titanium butoxide acid esters 0.1

By the slow aggegation of obtained resin, organic agglutination particle (aggegation polyester granules) is obtained.

Preparation example 5：The preparation of particle masterbatch bits 1

Using a part for the M-phthalic acid copolymerization polyethylene terephthalate 1 as above obtained, and using flat Equal particle diameter (marks in table for 1.0 μm of barium sulfate particles and is₄.) as void initiating agent, with society of Kobe Steel NEX- T60 serial type extruders, so that the content of barium sulfate particles is 63 relative to the quality of obtained masterbatch bits (master chip) Quality % mode is mixed, and is extruded under 260 DEG C of resin temperature, prepares the inorganic particulate containing barium sulfate particles Masterbatch bits 1.

Preparation example 6：The preparation of particle masterbatch bits 2

Into the M-phthalic acid copolymerization polyethylene terephthalate 2 as above obtained, aggegation titanium dioxide silicon grain is used as Sub- A, mixing Tosoh Silica Corporation (East ソーシリカ Co., Ltd.) AY-603 processed is 8 mass %, Extruded under 235 DEG C of melt temperature, prepare inorganic particulate masterbatch bits 2.

Preparation example 7 ~ 14：The preparation of particle masterbatch bits 3 ~ 10

Into the M-phthalic acid copolymerization polyethylene terephthalate 3 as above obtained, inertia as shown in table 1 is added Particle simultaneously is mixed to for content as shown in table 1, be extruded under 235 DEG C of melt temperature, prepare particle masterbatch Bits 3 ~ 10.

Table 1

It should be noted that, SHIN-ETSU HANTOTAI organic siliconresin company system KMP series is used as organic siliconresin particle, propylene is used as Acid resin particle uses ponding chemical conversion product society MBX series.

Preparation example 15：The preparation of particle masterbatch bits 11

Into the polyethylene terephthalate 2 of the copolymerization M-phthalic acid as above obtained, addition is obtained in preparation example 4 To aggegation polyester granules and mixed so that its content be 15 mass %, extruded under 235 DEG C of melt temperature, system Standby particle masterbatch bits 11.

Reference example 1

(preparation of white reflective film)

M-phthalic acid copolymerization polyethylene terephthalate 1 obtained above and particle masterbatch bits 1 are used as reflection The raw material of layer (A layers), is used as support layer (B by M-phthalic acid copolymerization polyethylene terephthalate 2 and particle masterbatch bits 2 Layer) raw material, to make each layer be mixed as the composition described in table 2 in the way of, input extruder in, A layers 255 DEG C melt Melt under extrusion temperature, B layers at a temperature of 230 DEG C of melting extrusion, are collaborated, to form such as table 2 using 3 layers of feed block assembly The Rotating fields of shown B layers/A layers/B layers, keep the laminated arrangement to be directly shaped to sheet by die head.Now, each extrusion is adjusted The discharge rate of machine, so that B layers/A layers/B layers of thickness ratio is 10/80/10 after biaxial stretch-formed.And then by the piece timber-used surface temperature The unstretching film of cooling and solidifying is made in the cooling drum spent for 25 DEG C.By the unstretching film by 73 DEG C of preheating zone, then pass through 75 DEG C of preheating zone, importing remains 92 DEG C of longitudinal stretching area, is being longitudinally stretched to 2.9 times, is being carried out with 25 DEG C of roller groups cold But.Then, while the two ends of film are fixed with clip by 115 DEG C of preheating zone, import and remain 130 DEG C of cross directional stretch Area, in cross directional stretch to 3.6 times.Then, thermal finalizations are carried out in 185 DEG C in stenter, is subtracted with the 2% wide rate that subtracts at 130 DEG C Transverse direction is carried out at wide temperature subtracts wide (width enters れ), then by the tip cut-off of film two, and hot wire-CVD is carried out with 2% longitudinal relaxation rate, cold But to room temperature, the biaxially-stretched film that thickness is 250 μm is obtained as shown in table 2.

The film is reclaimed and crushed, melting extrusion is carried out and expects bitsization to prepare from raw material is reclaimed, with reflecting layer A matter On the basis of amount, added into reflecting layer A as 35 mass % from raw material is reclaimed, thickness is obtained as described above for 250 μm Biaxially-stretched film, obtain white reflective film.The evaluation result of obtained film is illustrated in table 3.

Reference example 2

Aggegation silicon dioxide granule A is changed to aggegation silicon dioxide granule B (Grace Japan Co., Ltd. (グレースジャパ Application Co., Ltd.) C812 processed), in addition, it is prepared as biaxially-stretched film with reference example 1 and reclaims certainly Raw material, white reflective film, implementation evaluation are prepared using them.Evaluation result is illustrated in table 3.

Reference example 3

Aggegation silicon dioxide granule A is changed to aggegation silicon dioxide granule C (by Fuji Silysia Chemical Ltd. (シリシア KCCs of Fuji) Cariact processed (キャリア Network ト) P-10 remove 30 μm with air classifier Powder obtained from above), in addition, it is prepared as biaxially-stretched film and from raw material is reclaimed with reference example 1, uses them Prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Reference example 4

Aggegation silicon dioxide granule A is changed to aggegation silicon dioxide granule D (Fuji Silysia Chemical Ltd. (シリシア KCCs of Fuji) Cariact processed (キャリア Network ト) P-10), in addition, with reference example 1 It is prepared as biaxially-stretched film and from raw material is reclaimed, white reflective film, implementation evaluation is prepared using them.By evaluation result It is illustrated in table 3.

Reference example 5

(preparation of white reflective film)

Particle masterbatch bits 2 are changed to particle masterbatch bits 11, in addition, are prepared as with reference example 1 biaxial stretch-formed Film and certainly recovery raw material, white reflective film, implementation evaluation are prepared using them.Evaluation result is illustrated in table 3.

Reference example 6

By reflecting layer A void initiating agent be changed to as shown in table 2 the resin incompatible with polyester (cycloolefin, Polyplastics Co., Ltd.s system " TOPAS 6017S-04 "), in addition, it is prepared as twin shaft with reference example 1 and draws Stretch film and from raw material is reclaimed, white reflective film, implementation evaluation are prepared using them.Evaluation result is illustrated in table 3.

Reference example 7,8

Aggegation silicon dioxide granule A addition is set to as shown in table 2, in addition, is prepared as with reference example 1 Biaxially-stretched film and certainly recovery raw material, white reflective film, implementation evaluation are prepared using them.Evaluation result is illustrated in table 3 In.

Reference example 9

The form of preparation condition, Rotating fields is changed as shown in table 2, in addition, twin shaft is prepared as with reference example 1 Stretched film and certainly recovery raw material, white reflective film, implementation evaluation are prepared using them.Evaluation result is illustrated in table 3.

Comparative example 1

Agglutination particle is added not into the support layer B of reference example 1 (using M-phthalic acid copolymerization poly terephthalic acid second two Alcohol ester 2 replaces particle masterbatch bits 2.Moreover, regarding such layer as superficial layer C.), in addition, in the same manner as reference example 1 Prepare after the biaxially-stretched film that thickness is 250 μm, in the one side of the film, with the coating of die head apparatus for coating by following tune formula of liquid 1 The coating fluid that shown composition is constituted, is dried to form support layer B, obtains film in baking oven in 80 DEG C.Such branch The dry thickness for holding layer B is 2 μm.Then, this film is reclaimed and crushed, carried out melting extrusion and expect bitsization to prepare from recovery They are added 35 mass % in the A of reflecting layer on the basis of reflecting layer A quality and used, again as described above by raw material The film forming of film, but the foreign matter such as a large amount of non-fused mass of generation, gas trace when by film film forming are attempted in ground, and draftability is greatly reduced, so Sample can not be gathered.

(adjusting formula of liquid 1, solid component concentration is 35 mass %)

Particle：Ponding finished industrial BM30X-8 (crosslinked acrylic resin particle, non-porous paricles, powder) 17.6 quality %

Acryloid cement：DIC Acrydic (ア Network リディッ Network) A-817BA17.5 mass %

Crosslinking agent：Japanese polyurethane industry society Koronate (U ロネート) HL11.7 mass %

Organic solvent：The mass % of butyl acetate 53.2

It should be noted that, the solid constituent ratio of the support layer B obtained by above-mentioned formula each composition is as follows.

Particle：50 mass %

Adhesive：25 mass %

Crosslinking agent：25 mass %.

Embodiment 2

Aggegation silicon dioxide granule A is changed to aggegation silicon dioxide granule E (Tosoh Silica Corporation (East ソーシリカ Co., Ltd.) BY601 processed), in addition, it is prepared as biaxially-stretched film with reference example 1 and returns certainly Raw material is received, white reflective film, implementation evaluation are prepared using them.Evaluation result is illustrated in table 3.

Embodiment 3

Aggegation silicon dioxide granule A is changed to aggegation silicon dioxide granule F (Fuji Silysia Chemical Ltd. (シリシア KCCs of Fuji) Sylysia processed (サイリシア) 350), it is in addition, same with reference example 1 Prepare biaxially-stretched film and from raw material is reclaimed sample, white reflective film, implementation evaluation are prepared using them.Evaluation result is shown For in table 3.

Comparative example 4

Aggegation silicon dioxide granule A is changed to spherical silicon dioxide particle (marshy land KCC Silton (シ Le ト Application) JC), in addition, it is prepared as biaxially-stretched film and from raw material is reclaimed with reference example 1, is prepared using them White reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

From above-described embodiment 2,3, according to the present invention, it is possible to provide：The damage of light guide plate can fully be suppressed, meanwhile, i.e., Make recovery film and be used as preparing film from reclaiming raw material, film forming still excellent recyclable white reflective film.

Embodiment 10

(preparation of white reflective film)

It regard M-phthalic acid copolymerization polyethylene terephthalate 1 obtained above and particle masterbatch bits 1 as reflection The raw material of layer (A layers), is mixed so that the content of barium sulfate uses for 45 weight %, M-phthalic acid is total to by another aspect Poly- polyethylene terephthalate 3 and particle masterbatch bits 3 are mixed with as the institute of table 4 as the raw material of support layer (B layers) The content of record and use, input extruder in, using 3 layers feed block assemblies collaborated, to form B layers/A layers/B layers of layer Structure, keeps the laminated arrangement to be directly shaped to sheet by die head.Now, the discharge rate of each extruder is adjusted, so that B layers/A Layer/B layers of thickness ratio is changed into 10/80/10 after biaxial stretch-formed.And then the piece timber-used surface temperature is roused into system for 25 DEG C of cooling Into the unstretching film of cooling and solidifying.The unstretching film is imported into sensing heating roller group and 73 DEG C are preheated to, then side is from the upper of film So that film surface temperature is changed into 95 DEG C between lower 2 groups of rolls with infra-red light irradiation, while before being utilized with the draw speed of 350%/second The difference of roller afterwards is being longitudinally stretched to 2.9 times, is cooled down with 25 DEG C of roller group.Then, pressed from both sides at the two ends of film By 95 DEG C of preheating zone while son is fixed, imports and remain 110 DEG C of cross directional stretch area, expand the interval of clip so as to draw Speed is stretched for 5.8%/second, in cross directional stretch to 3.6 times.Then, thermal finalizations are carried out in 185 DEG C in stenter, width is subtracted with 2% Rate 130 DEG C subtract carry out at wide temperature it is horizontal subtract width, then by the tip cut-off of film two, heat pine is carried out with 2% longitudinal relaxation rate Relax, be cooled to room temperature, obtain the biaxially-stretched film that thickness is 250 μm.The evaluation result of obtained film is illustrated in table 4.

Embodiment 11 ~ 17, comparative example 5 ~ 11

The form (particle masterbatch bits) for the inert particle for making to make an addition in B layers, the Rotating fields of film, stretching condition such as table 4,5 It is shown, in addition, film is obtained similarly to Example 10.The evaluation result of obtained film is illustrated in table 4,5.

From above-described embodiment 10 ~ 17, according to the present invention, it is possible to provide can fully suppress same with the stickup of light guide plate When, suppress the damage of light guide plate and suppress the white reflective film that particle comes off.

Industrial applicability

The white reflective film of the present invention suppresses the damage of light guide plate and suppresses particle and come off, even if using from reclaiming raw material The film forming of still difficult reduction film, so the area source reflecting plate for possessing light guide plate can be especially suitable for use as, wherein, it can be suitable as It is used for the reflectance coating of side light type backlight unit as such as liquid crystal display device.

Claims

1. a kind of white reflective film, the white reflective film includes reflecting layer A and support layer B, the support layer B is by thermoplastic The thermoplastic resin composition containing agglutination particle is formed in property resin,

The primary particle size dp of the agglutination particle is less than 3 μm, and aggregate particle size ds is less than 8 μm, using support layer B volume as base Content in standard, support layer B is below the volume % of more than 1 volume % 50,

The outermost layer of at least side of support layer B formation white reflective films, formed the outermost support layer B's and reflecting layer 10 mean roughness Rz on the surface of the opposite sides of A meet following formula (1),

The aggregate particle size ds and support layer B of agglutination particle in support layer B thickness t meet following formula (2)：

0.1×ds(μm)≤Rz(μm)≤0.7×ds(μm)···(1)

0.07≤ds(μm)/t(μm)≤20···(2)。

2. the white reflective film of claim 1, wherein, volatile organic solvent amount is below 10ppm.

3. the white reflective film of claim 1 or 2, wherein, reflecting layer A voidage rate is the volume % of more than 15 volume % 70 Hereinafter, support layer B voidage rate is that more than 0 volume % is less than 15 volume %.

4. the white reflective film of claim 1 or 2, it is used as edge-lit backlight unit reflecting plate.