CN105866866A

CN105866866A - White reflective film

Info

Publication number: CN105866866A
Application number: CN201610410121.2A
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: 2016-08-17
Also published as: CN105866867A; CN105866867B; KR20140122715A; CN104603647B; TWI595271B; TWI632403B; TW201809737A; TWI632402B; TW201418790A; CN104603647A; TW201809738A; WO2014021476A1; KR101524992B1

Abstract

The invention discloses a white reflective film comprising: a reflective layer A; a support layer B which contains a thermoplastic resin and inactive particles that are dispersed within the thermoplastic resin, and which forms the outermost layer on at least one side; and protrusions caused by the inactive particles on the surface on the reverse side of the support layer B to the reflective layer A, the support layer B forming the outermost layer. This film can sufficiently suppress adhesion to a light guide plate, can suppress damage to a light guide plate, and can suppress particle loss. Furthermore, even if the film is recovered and used as a self-recovered raw material in the manufacture of a film, the resulting film exhibits excellent film forming properties.

Description

White reflective film

The application is filing date on August 2nd, 2013, Application No. 201380022733.9, invention entitled " white is anti- Penetrating property film " the divisional application of application for a patent for invention.

Technical field

The present invention relates to white reflective film.Particularly relate to the white reflective film for liquid crystal indicator.

Background technology

The back light unit of liquid crystal indicator (LCD) has directly-below type and sidelight (edge light) type, and described directly-below type exists The back side of display panels possesses light source, and then possesses reflectance coating in light source back surface；Described side light type is at display panels The back side be arranged in the back side and possess the light guide plate of reflecting plate, possess light source in the side of such light guide plate.In the past, as being used for The back light unit of large LCD, from the viewpoint of the excellent in uniformity of the brightness in the brightness and picture of picture, main use is just 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, even if the uniformity of the lightness in brightness and picture is also improved, not only in side light type backlight unit In more small-sized equipment, also begin to use side light type backlight unit in large LCD.It addition, its reason is the most also have Can the advantage of thinning LCD.

In side light type backlight unit, form the structure that light guide plate directly contacts with reflectance coating.Therefore, in such structure In, if light guide plate and reflectance coating are pasted, then the brightness of the part pasted becomes abnormal, has asking of deviation in the face producing brightness Topic.Accordingly, it would be desirable to have gap (gap) between light guide plate and reflectance coating, and such gap is kept certain.Such as, may be used The gap between light guide plate and reflectance coating is kept certain by having pearl on the surface of reflectance coating, it is possible to prevent theirs Paste.

But, if the light guide plate now formed by softer raw material contacts with reflectance coating, then have because of reflectance coating or surface Pearl and the problem of damaging light guide plate.As its countermeasure, such as Japanese Unexamined Patent Publication 2003-92018 publication, Japanese Unexamined Patent Application Publication 2008- No. 512719 publications are such, have the report of the reflective sheet possessing the antisitic defect layer using elastomer class pearl.

But, if making as above-mentioned Japanese Unexamined Patent Publication 2003-92018 publication, Japanese Unexamined Patent Application Publication 2008-512719 publication With soft pearl, although the damage of light guide plate then can be suppressed, but cannot reach and required in recent years guarantee gap, if such as applying Bigger stress, then possibly cannot guarantee gap, it is impossible to suppression is pasted.For such problem guaranteeing gap, as pearl, examine Consider and use the inorganic particulate such as true spherical silicon dioxide or there is the pearl that the hardness such as organic filler of cross-linked structure is high, but they cannot The damage of suppression light guide plate.It addition, using the high pearl of such hardness, (described pearl has fully to reach and guarantees the journey in gap The size of degree) time, the present inventor's new discovery also pays close attention to problems with: is reclaiming the film not forming goods, is being used as from reclaiming In the case of new film prepared again by raw material, remain in the pearl reclaimed in raw material be mixed in film, particularly in reflecting layer, thus film Rupture multiple, the film property step-down of film, substantially can not be from reclaiming.

Summary of the invention

Therefore, it is an object of the invention to, it is provided that a kind of white reflective film, described white reflective film suppression light guide plate Damage, and suppress particle to come off.

Other purpose and advantage that the present invention is other can be clear and definite by following description.

According to the present invention, the above object and advantages of the present invention can be reached by a kind of white reflective film, described white Reflective membrane have reflecting layer A and support layer B, described support layer B by comprise in polyester resin mean diameter (d) be 2 μm with The polyester and resin composition of the inert particle below upper 75 μm is formed,

Support that layer B forms the outermost layer of at least side of white reflective film, form this outermost support layer B with reflection The surface of layer A opposition side has the projection formed by described inert particle,

On this surface, projection frequencies more than height 5 μm is 10⁶~10¹⁰Individual/m²,

Described projection by described inert particle by constitute the described polyester resin of described support layer B with more than 50nm 10 μm below Coating thickness be coated to surface and formed.

(hereinafter referred to as white reflective film a) can successfully reach this to white reflective film according to the feature with above-mentioned a Bright above-mentioned 1st purpose；White reflective film (the hereinafter referred to as white reflective of the present invention according to the feature with above-mentioned b Film b), can successfully reach above-mentioned 2nd purpose of the present invention.

Accompanying drawing explanation

Fig. 1 is to illustrate that the light guide plate Damage Evaluation of the present invention and particle come off the schematic diagram of the method evaluated.

Fig. 2 is the schematic diagram of the structure illustrating that the adhesion plaque (adherence speckle) for the present invention evaluates.

Fig. 3 is the photo of an example in the cross section of the projection illustrating 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, be respectively provided with reflecting layer A and Support layer B.

In detail below each constituent constituting the present invention is illustrated.

First, white reflective membrane a is illustrated.

[reflecting layer A]

The reflecting layer A of the present invention is to be formed by thermoplastic resin and void initiating agent, by containing void initiating agent in layer Containing space so that present the layer of white.As such void initiating agent, details are described later, such as, can use inorganic grain Son and the resin constituting the thermoplastic resin of this reflecting layer A incompatible (have the situation of referred to as incompatible resin below.).It addition, A reflectance under 550nm wavelength in reflecting layer is preferably more than 95%, more preferably more than 96%, particularly preferably 97% with On.Thus become easily the reflectance of white reflective film a to be set to preferred scope.

As it has been described above, reflecting layer A has space in layer, the volume in the such space volume institute relative to reflecting layer A The ratio (voidage rate) accounted for is preferably in the range of 15 ~ 70 volume %.By being set to such scope, reflectance can be made Improve effect to uprise, become the reflectance as above that is easy to get.It addition, the raising effect of film property can be made to uprise.In space In the case of volume fraction is too low, the trend obtaining preferred reflectance in distress.From such a viewpoint, the space of reflecting layer A The lower limit of volume fraction 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 property.From such a viewpoint, the upper limit of the voidage rate of reflecting layer A is the most excellent Elect 65 volume %, particularly preferably 60 volume % as.

Voidage rate can be reached by the adjustment kind of void initiating agent of reflecting layer A, size, amount.

(thermoplastic resin)

As the thermoplastic resin of composition reflecting layer A, include, for example out by polyester, polyolefin, polystyrene, acrylic resin (acryl) thermoplastic resin formed.Wherein, from the viewpoint of the white reflective film obtaining mechanical property and excellent heat stability Set out, preferably polyester.

As such polyester, the polyester that by dicarboxylic acid component and diol component formed is preferably used.As this dicarboxylic acids Composition, can list derive from p-phthalic acid, M-phthalic acid, NDA, 4,4 '-biphenyl dicarboxylic acid, adipic acid, The composition of decanedioic acid etc..As diol component, can list derive 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 So polyethylene terephthalate can be homopolymer, but from film suppresses when uniaxially or biaxially stretching crystallization make stretching Property, film property become good aspect and set out, preferred copolymer.As copolymer composition, can list above-mentioned dicarboxylic acid component, two Alcohol composition, but from thermostability and film property and from the viewpoint of depositing, preferably M-phthalic acid, NDA.With polyester On the basis of 100 moles of % of all dicarboxylic acid component, for example, 1 ~ 20 mole % of the ratio of copolymer composition, preferably 2 ~ 18 moles %, enter One step is preferably 3 ~ 15 moles of %, particularly preferably 7 ~ 11 moles %.By the ratio of copolymer composition is set to this scope, film property Raising excellent effect.It addition, thermal dimensional stability is excellent.

(void initiating agent)

In the A of reflecting layer, in the case of using inorganic particulate as void initiating agent, as inorganic particulate, preferred white without Machine particle.As this white inorganic particle, the particle of barium sulfate, titanium dioxide, silicon dioxide, calcium carbonate can be exemplified.These As long as inorganic particulate selects mean diameter and content to make white reflective film have suitable reflectance, they are without special Limit.As long as preferably making reflecting layer A, the reflectance of white reflective film become the preferred scope of the present invention.As long as it addition, The voidage rate making reflecting layer A becomes the preferred scope of the present invention.In view of these situations, the average particle of inorganic particulate Footpath for example, 0.2 ~ 3.0 μm, preferably 0.3 ~ 2.5 μm, more preferably 0.4 ~ 2.0 μm.It addition, with the quality of reflecting layer A On the basis of, the content of inorganic particulate preferably 20 ~ 60 mass %, further preferred 25 ~ 55 mass %, most preferably 31 ~ 53 mass %. It addition, by using particle shape as above, can the most moderately disperse, the coagulation difficulty of particle occurs, available Without the film of thick projection, it addition, rupturing when oversize grain simultaneously also can be suppressed to become the stretching of starting point.Inorganic particulate can be to appoint The shape of particle of meaning, such as, can be tabular, spherical.Inorganic particulate also can carry out improving the surface of dispersibility and process.

In the case of using incompatible resin as void initiating agent, as incompatible resin, if with the heat constituting layer Plastic resin is incompatible, then without particular determination.Such as, in the case of such thermoplastic resin is polyester, preferred polyolefm, Polystyrene etc..They can be the form of particle.As long as it addition, its content selects average particle in the same manner as the situation of inorganic particulate Footpath, content make white reflective film have suitable reflectance, and they are without particular determination.As long as preferably make reflecting layer A, The reflectance of white reflective film becomes the preferred scope of the present invention.As long as it addition, making the voidage rate of reflecting layer A become Preferred scope for the present invention.In view of these situations, on the basis of the quality of reflecting layer A, content preferably 10 ~ 50 matter Amount %, further preferred 12 ~ 40 mass %, most preferably 13 ~ 35 mass %.

(other composition)

As long as not hindering the purpose of the present invention, reflecting layer A can containing other composition, such as UV absorbent, antioxidant, Antistatic additive, fluorescent whitening agent, wax, the particle being different from void initiating agent or resin etc..

[supporting layer B]

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

(polyester resin)

As being used as to support the polyester of the polyester resin of layer B, the polyester as the polyester of above-mentioned reflecting layer A can be listed.? In these polyester, from the viewpoint of the white reflective film obtaining mechanical property and excellent heat stability, preferably aromatic polyester, Particularly preferably polyethylene terephthalate.Although polyethylene terephthalate can be homopolymer, but presses down from improving From the viewpoint of the raising effect of the guide-lighting dash-board injury of system, preferred copolymer.As such copolymer composition, above-mentioned two can be listed Carboxylic acid composition, diol component, but equally from the viewpoint of suppression damage, preferably M-phthalic acid, NDA.With poly- On the basis of 100 moles of % of all dicarboxylic acid component of ester, the ratio of copolymer composition is preferably 1 mole of more than %, and more preferably 1.5 rub You are more than %, more preferably 2 moles of more than %, particularly preferably 3 moles more than %.Additionally, it is preferred that be 20 moles of below %, more It is preferably 18 moles of below %, more preferably 15 moles of below %, particularly preferably 12 moles below %.By being copolymerized into The ratio divided is set to more than lower limit, can improve the raising effect of suppression light guide plate damage especially.On the other hand, by being set to the upper limit Hereinafter, become easily because of crystalline orientation etc., there is the hardness of appropriateness, thus can improve the raising effect that suppression is pasted.

(inert particle)

As the inert particle of support layer B, can be organic inert particle, inorganic inert particle or organo-mineral complexing inertia grain Son.

As organic inert particle, include, for example out 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 being easily formed From the viewpoint of the projection of the hardness of appropriateness, particularly preferred organic siliconresin particle, acrylic resin particle.

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

It addition, in the present invention, as inert particle, it is possible to use such as the inorganic particulate being coated to by Organic substance, by inorganic Organo-mineral complexing inert particle as the organic filler that thing is coating.Specifically, as organo-mineral complexing particle, such as Following particle can be listed: by side chain or end, there is the high score of organo-metallic compound base as silyl alkyl Son with inorganic compound composition as silicon dioxide by covalent bond be combined obtained by organic-inorganic mixing material formation Particle；Inert inorganic particle surface fusible coating just like crosslinked polystyrene as grain obtained by organic polymer microgranule Son；Or particle obtained by inert inorganic particulate as the adhesion of inertia organic polymer particle surface is coating just like aluminium oxide Deng.

In the present invention, from the viewpoint of easily playing more excellent effect, as the preferred inorganic particulate of inert particle.Special Not when using inorganic inert particle as inert particle, being typically due to inorganic inert particle hard, so easily light guide plate being made Become damage, therefore use the present invention particularly useful.

In order to suppress to paste, as long as supporting that the mean diameter of the inert particle of layer B and content select such as to meet following 10 points Scope as mean roughness Rz or projection frequency.

Such as, keeping certain from by the interval of light guide plate and film, easily from the viewpoint of they stickups of suppression, mean diameter is excellent Elect 2 μm ~ 100 μm as.If mean diameter is too small, then Rz has the trend diminished, and has white reflective film partly to adhere to leaded light The trend that the probability of plate uprises.From such a viewpoint, the lower limit of mean diameter is preferably 5 μm, more preferably 10 μm, particularly preferably 15 μm.On the other hand, in the case of excessive, there is particle to become caducous trend, if occurring de- Fall, then in back light unit, form white-spot defects.From such a viewpoint, the higher limit of mean diameter is preferably 80 μm, enters One step is preferably 75 μm, particularly preferably 70 μm, most preferably 65 μm.

It addition, such as on the basis of the volume supporting layer B, content is preferably 0.1 volume % ~ 20 volume %.If very few, then have Guarantee the trend of the raising effect step-down in gap.Therefore, lower limit more preferably 0.2 volume %, particularly preferably 0.3 body Long-pending %.On the other hand, if too much, then there is the trend of the raising effect step-down suppressing particle to come off.Therefore, higher limit is the most excellent Elect 15 volume %, particularly preferably 12 volume % as.

(other composition)

Do not hindering in the range of the purpose of the present invention, supporting that layer B can be containing the composition beyond above-mentioned constituent.As so Composition, include, for example out UV absorbent, antioxidant, antistatic additive, fluorescent whitening agent, wax, be different from above-mentioned lazy The particle of property particle or resin etc..

It addition, support that layer B, can be able to improve by being set to such form containing the void initiating agent enumerated in the A of reflecting layer The raising effect of reflectance.Otherwise, if making the content of the void initiating agent of support layer B reduce or not contain void initiating agent, then The raising effect that can make film property uprises.From these viewpoints, support that the voidage rate of layer B (supports the body in the space of layer B The long-pending ratio relative to the volume supporting layer B) preferably 0 volume % ~ less than 15 volume %, more preferably 0 ~ 5 volume %, special You Xuanwei 0 ~ 3 volume %.The most in the present invention, owing to can play the raising effect of reflection characteristic and draftability, institute simultaneously Particularly preferably to use preferred voidage rate and the preferred voidage of described support layer B of above-mentioned reflecting layer A simultaneously Rate.

(supporting the form of layer B)

In the present invention, polyester resin as above formed and formed containing the support layer B of inert particle as above The outermost layer of at least side of white reflective film.And, formed such outermost support layer B with reflecting layer A phase There is on the surface tossed about the projection formed by above-mentioned inert particle.Additionally, this projection is by constituting the polyester tree supporting layer B Fat is coated to the structure of above-mentioned inert particle.

When polyester resin is coated to inert particle, coating thickness is in the range of the μm of 50nm ~ 10.Herein, coating thickness is The thickness of the apex polyester resin that phalangeal process rises.Due to coating thickness within the above range, the damage of light guide plate can be suppressed.Separately Outward so that projection has the hardness of appropriateness, thus can ensure that gap, can suppress to paste.If coating thickness is the thinnest, do not simply fail to The damage of suppression light guide plate, and have the probability causing particle to come off because of friction.It addition, become difficulty to guarantee gap.Another Aspect, the coating blocked up particle making to form this projection of thickness is present in the deep inside supporting layer B, thus has shape for lugs also Become the probability of big " gently " shape of curvature, thus be difficult to prevent the stickup with light guide plate.From these viewpoints, projection The lower limit of coating thickness that formed by polyester resin of inert particle be preferably 200nm, more preferably 1 μm；It addition, higher limit It is preferably 8 μm, more preferably 7.5 μm.

So, owing to, in the white reflective film of the present invention, the outermost layer at white reflective film has by polyester tree Fat is coated to the projection of the structure of inert particle with specific coating thickness, thus, when being connected use with light guide plate, can suppress because being somebody's turn to do Projection and damage light guide plate.It addition, particle can be suppressed to come off.It addition, can ensure 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.

Additionally, from the viewpoint of the gap guaranteeing light guide plate and reflectance coating, formed outermost support layer B with instead Penetrating a layer surface for A opposition side, above-mentioned projection needs the height with appropriateness, and exists with the frequency of appropriateness.

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

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

Additionally, for the damage suppressing light guide plate further, the most easily guarantee when light guide plate is crimped with reflectance coating enough Gap, and prevent particle from coming off from film surface further and become foreign body, mesh that display quality reduces because of screen defect , above-mentioned projection preferred hardness is 10⁰~10³。

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

Above-mentioned projection hardness can represent by values below: based on JIS Z2244, with microhardness testers (such as Elionix ENT-1100a the most processed) value that measures.Can use Berkovich (バ U PVC ッチ) pressure head (between rib positive the three of angle=115 ° Pyramidal front end), will be pressed into load (P) and be set to 500mgf (about 4.9mN), according to the maximum compression distance (h [μm]) measured Value, calculates hardness (H) by following formula.

H=0.038×P/h²

Measure and preferably (select to be highly that the method for the projection of more than 5 μm is for preferably measuring to the projection randomly drawed from sample The one of method), such as multiple projections of more than such as 30 are carried out, using their meansigma methods as the hardness of projection.It addition, it is prominent Height can be confirmed by laser microscope.

[Rotating fields]

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

It addition, support layer B thickness (have multiple in the case of, be formed into light guide plate side outermost 1 layer Thickness) be preferably 10 ~ 70 μm.Thus, with the combination of shape and state of above-mentioned preferred inert particle, preferred Rz and projection easily it are set to The form of frequency, easily guarantees the gap with light guide plate.It addition, the raising effect of reflectance and the raising effect of draftability can be made to become High.If crossing thin, then difficulty reaches preferred Rz, have particle come off inhibition reduce trend.It addition, there is the raising of draftability to imitate The really trend of step-down.On the other hand, if blocked up, then there is the trend of the raising effect step-down of reflectance, and in distress obtain preferably Rz and the trend of projection frequency.From such a viewpoint, the lower limit of thickness more preferably 20 μm；It addition, higher limit More preferably 60 μm.

In the present invention, in order to easily make with the rising height represented by the coating thickness of above-mentioned inert particle and Rz for this The scope of bright middle regulation, supports that the mean diameter (d) of the inert particle in layer B preferably meets following with the thickness (t) supporting layer B Formula (2)-1,

0.05≤d(μm)/t(μm)≤20···(2)-1

More preferably meet following formula (2)-2,

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 of this d/t value is too small, become the difficult projection generating enough height, have the gap that guarantees with light guide plate Improve the trend of effect step-down；On the other hand, in the case of excessive, there is coating thickness to become the trend of easily deficiency, have suppression The trend of 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；It addition, higher limit is particularly preferably 2.0, more preferably 1.8.

When reflecting layer A being expressed as A, support layer B being expressed as B, the stepped construction of white reflective film can list 2 Rotating fields of B/A, the 3-tier architecture of B/A/B, 4 Rotating fields of B/A/B/A or B is at least configured at outermost the 5 of either side The multiple structure that layer is above.Particularly preferably 2 Rotating fields of B/A, the 3-tier architecture of B/A/B.Most preferably 3 layers of knot of B/A/B Structure, the problems such as raw curling of having difficult labour.

About reflecting layer A and support layer B, when the thickness that white reflective film is overall is calculated as 100%, preferably reflecting layer A Thickness proportion be 50 ~ 90% and support the thickness proportion of layer B 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 having multiple each layer, the thickness proportion of each layer refers to that their cumulative thickness is each other 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, can have other Layer.Such as, can have to give antistatic behaviour or the layer of the function such as electric conductivity, ultra-violet resistance.

[characteristic of reflectance coating]

(reflectance, brightness)

The white reflective film of the present invention from support layer B side measure reflectance be preferably more than 96%, more preferably 97% with On, more preferably more than 97.5%.Owing to reflectance is more than 96%, in the situation for liquid crystal indicator or illumination etc. Under, available high brightness.Such reflectance can be by being set to make the preferred shapes such as the voidage rate of reflecting layer A uprises State, or by making the thickness of reflecting layer A thickening or making the lower thickness etc. of support layer B that the form of each layer is set to preferred shape State is reached.

It addition, from supporting that the brightness that layer B side measures can be tried to achieve by following assay method, preferably 5400cd/m²Above, enter The one preferred 5450cd/m of step²Above, particularly preferred 5500cd/m²Above.

In white reflective film, when using with light guide plate, above-mentioned reflectance and brightness are become light guide plate side one 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 measured by following method is preferably below 10ppm.By This, the durability that such as can exemplify the light guide plate directly contacted with reflectance coating in sidelight liquid crystal display puies forward advantages of higher. From such a viewpoint, more preferably below 5ppm, more preferably below 3ppm, preferably 0ppm.In the present invention In, in order to make volatile organic solvent quantitative change few, in the formation supporting layer B, preferably do not use the solution coating using organic solvent Method, and use following method.

Then, white reflective membrane b is illustrated.

[reflecting layer A]

The described above to white reflective membrane a can be directly applied in explanation to reflecting layer A.That is, to white reflective membrane a upper State and bright also include (thermoplastic resin), (void initiating agent) and the explanation of (other composition), for white reflective film b, Can directly apply.

[supporting layer B]

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

(thermoplastic resin)

As constituting the thermoplastic resin supporting layer B, the thermoplastic as the thermoplastic resin constituting above-mentioned reflecting layer A can be used Property resin.Wherein, from the viewpoint of the white reflective film obtaining mechanical property and excellent heat stability, preferably polyester tree Fat.

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

(agglutination particle)

In the present invention, as the particle of the concave-convex surface of the stickup formed in order to guarantee gap, suppression and light guide plate, by adopting With the agglutination particle that present invention provide that so that certainly reclaiming of film can be carried out, prepare film even if using from recovery raw material, the one-tenth of film Film is the most excellent.Think that its reason is, if agglutination particle, then moderately pulverized at preparation particle in time reclaiming raw material.

As the agglutination particle of support layer B, can be organic agglutination particle or inorganic agglutination particle.As organic coagulation grain Son, include, for example out polyester agglutination particle, acrylic resin (acryl) agglutination particle, polyurethane agglutination particle, polyethylene coagulate Collection particle etc..Wherein, preferably polyester agglutination particle, even if polyester agglutination particle is considered not fill pulverizing in recovery process Point, the compatibility with the polyester as primary raw material is still good, and the impact on film property etc. is limited.As inorganic agglutination particle, Include, for example out silicon dioxide agglutination particle, aluminium oxide agglutination particle, pottery agglutination particle etc..If particle is really up to the mark, then drawing Stretching during film easily rupturable, film property is poor, so preferred silicon dioxide agglutination particle from this viewpoint.

About the agglutination particle of support layer B, the aggregate particle size (ds) as the mean diameter of agglutination particle must be over 10 μ M and be below 100 μm.Thus the interval of light guide plate and film is kept certain, can favorably inhibit them and paste, meanwhile, Comprising situation about using from reclaiming raw material, draftability during film forming becomes good.If aggregate particle size is too small, then 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, more preferably 15 μm, particularly preferably 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, i.e. there is the trend from the film property difference reclaiming caudacoria.It addition, there is particle to become easy The trend come off, if falling off, then 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.

It addition, the primary particle size (dp) constituting the primary particle of agglutination particle is preferably more than 0.01 μm, additionally, it is preferred that be Below 5 μm.By meeting this primary particle size and above-mentioned aggregate particle size scope simultaneously, can further improve use in time reclaiming raw material The raising effect of film property.If primary particle size is too small, then there is the trend that the intensity of agglutination particle excessively dies down, therefore obtain foot Enough big aggregate particle sizes become difficulty.From such a viewpoint, the lower limit of primary particle size is more preferably 0.02 μm, further It is preferably 0.03 μm, particularly preferably 0.05 μm.On the other hand, in the case of excessive, even if in preparation in time reclaiming raw material Offspring is destroyed, still can the remaining bigger particle of particle diameter, have the trend of the raising effect step-down of the film property after recovery. From such a viewpoint, higher limit is more preferably 4 μm, more preferably 3 μm, particularly preferably 2 μm, most preferably 1 μm.

It addition, on the basis of the volume supporting layer B, support that the content of the agglutination particle of layer B is 1 ~ 50 volume %.If it is very few, Then the concave-convex surface of white reflective film is few, it is impossible to by and the interval of light guide plate keep certain.Therefore, lower limit is further preferred It is 2 volume %, particularly preferably 3 volume %.On the other hand, if too much, then support the intensity difference of layer B, have production energy during film forming The mechanical strength of the film that power deteriorates or obtains becomes not enough trend.Additionally, the particle quantitative change in time reclaiming is many, improve the response rate Become difficulty, so becoming problem.Therefore, higher limit more preferably 45 volume %, particularly preferably 40 volume %.

(other composition)

Inert particle in this explanation can be replaced with coagulation grain by the explanation to above-mentioned (other the composition) of white reflective membrane a Son and apply.

(supporting the form of layer B)

In the present invention, thermoplastic resin as above formed, support layer B containing agglutination particle as above is formed The outermost layer of at least side of white reflective film.Formed such outermost support layer B with A opposition side, reflecting layer (there is the situation of referred to as outermost surface on surface) below, has the projection formed by above-mentioned agglutination particle.From guarantee light guide plate with From the viewpoint of the gap of reflectance coating, at outermost surface, such projection needs the height with appropriateness.

Therefore, in the present invention, 10 mean roughness (Rz) of outermost surface and the agglutination particle 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)

Owing to meeting above-mentioned formula (1), the agglutination particle at outermost surface is moderately buried in support layer and moderately protrudes, Making have concave-convex surface, described concave-convex surface has the height of appropriateness, thus can play the effect guaranteeing gap of excellence.? In above-mentioned formula, the situation that the value of Rz is less than the value on the left side represents that agglutination particle is excessively buried in the form supported in layer B, therefore has Guarantee the trend of the weak effect in gap.From such a viewpoint, it is preferably the form meeting 0.2 × ds (μm)≤Rz (μm), More preferably meet the form of 0.3 × ds (μm)≤Rz (μm).On the other hand, the situation that the value of Rz is bigger than the value on the right represents solidifying Collection particle, from the form supporting that layer B excessively highlights, has the trend that particle deciduous when contacting is poor with light guide plate.From such sight Point sets out, and preferably meets the form of Rz (μm)≤0.6 × ds (μm), more preferably meets Rz (μm)≤0.5 × ds's (μm) Form.

In order to be set to form as above, as long as considering the aggregate particle size of the agglutination particle used, adjusting and supporting layer B's Thickness.Such as, in the case of there is the agglutination particle of certain aggregate particle size, if making the lower thickness of support layer B, then become For the value of Rz close to the direction of the value on the right, if the most thinning, then exceed the value on the right.On the other hand, if making the thickness of support layer B Spend thickening, then become the value direction close to the value on the left side of Rz, as the most thickening, then less than the value on the left side.It is contemplated that it is such Trend is adjusted.

As the form of the concave-convex surface of outermost surface, from the viewpoint of guaranteeing the light guide plate gap with reflectance coating, It is preferably the projection frequency of appropriateness.

At outermost surface, it is highly that the number of the preferred per unit area of projection frequency of the projection of more than 5 μm is 10⁶~ 10¹⁰Individual/m².By this projection frequency and above-mentioned Rz, the gap with light guide plate can be guaranteed more fully, the raising effect that suppression is pasted Fruit is excellent.If projection frequency is very few, then suppress the raising weak effect pasted.On the other hand, if projection frequency is too much, then there is particle The probability come off improves or the trend of reflectance reduction.

[Rotating fields]

It addition, support layer B thickness (have multiple in the case of, be formed into light guide plate side outermost 1 layer Thickness) be preferably 10 ~ 70 μm.Thus, and the combination of shape and state of above-mentioned preferred agglutination particle, easily by the secondary grain of agglutination particle The relation of footpath ds and 10 mean roughness Rz is set to preferably form as above, easily guarantees the gap with light guide plate.Separately Outward, easily the form of Rz and projection frequency is set to above-mentioned preferred form.It addition, raising effect and the draftability of reflectance can be made Raising effect uprise.If crossing thin, then difficulty reaches preferred Rz, have particle come off inhibition reduce trend.It addition, draw The trend of the raising effect step-down of stretching property.On the other hand, if blocked up, then there is the trend of the raising effect step-down of reflectance, and have Rare to preferred Rz and the trend of projection frequency.From such a viewpoint, lower limit more preferably 20 μm；It addition, Higher limit more preferably 60 μm.

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

0.05≤ds(μm)/t(μm)≤20···(2)-1’

More preferably meet following formula (2)-2 ',

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’。

Owing to meeting above-mentioned formula, at outermost surface, easily having concave-convex surface, described concave-convex surface has the height of appropriateness Degree, thus can make the raising effect guaranteeing gap uprise.In above-mentioned formula (2)-1 ' in, the feelings that value at ds/t is less than the value on the left side Under condition, there is agglutination particle to be easily buried in the trend supported in layer B, have the trend improving weak effect guaranteeing gap.From such Viewpoint is set out, and lower limit particularly preferably meets the form of 0.07≤ds (μm)/t (μm), more preferably meets 0.09≤ds (μ The form of m)/t (μm), more preferably meets the form of 0.3≤ds (μm)/t (μm), particularly preferably meets 0.4≤ds The form of (μm)/t (μm).On the other hand, in the value of ds/t than above-mentioned formula (2)-1 ' the value on the right big in the case of, have coagulation The particle trend improving weak effect come off easily from supporting trend prominent for layer B, when having suppression 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, can have other Layer.Such as, can have to give antistatic behaviour or the layer of the function such as electric conductivity, ultra-violet resistance.It addition, particularly passing through When rubbing method or laminating arrange support layer B, it is possible to the layer of the setting film property in order to improve the film with reflecting layer A.

[characteristic of reflectance coating]

(reflectance, brightness)

The explanation to white reflective membrane a can be directly applied in relevant explanation.

(volatile organic solvent amount)

In the white reflective film of the present invention, the volatile organic solvent amount measured by following method is preferably below 10ppm.By This, obtaining from reclaiming raw material, and when using it by film film forming, the angry trace (gas mark) of difficult labour, draftability improves.From such Viewpoint is set out, more preferably below 5ppm, more preferably below 3ppm, preferably 0ppm.In the present invention, in order to make Volatile organic solvent quantitative change is few, does not preferably use in the formation supporting layer B and uses the solution rubbing method of organic solvent to use Following method.

Then, white reflective membrane a and the preparation method of b are described.

[preparation method of film]

Following description prepares an example of the method for white reflective film a or b of the present invention.

When preparing the white reflective film of the present invention, preferably logical on the reflecting layer A obtained by extrusion by melting etc. Cross molten resin rubbing method (including melt extruding resin-coated method), coetrusion and laminating etc. to be formed and support layer B, thus shape Become stepped construction.Wherein, the white reflective film of the present invention particularly preferably by reflecting layer A and supports layer B layer by coetrusion Fold and prepare.Additionally, it is preferred that by reflecting layer A and support the direct stacking of layer B by coetrusion.By so entering with coetrusion Row stacking, not only can make reflecting layer A with support layer B interface adhesiveness uprise, and without experience for by film laminating or By forming the operation supporting layer B after film film forming again, so volume production can inexpensively, easily be carried out.

Below to using polyester as constituting the thermoplastic resin of reflecting layer A and constituting the thermoplastic resin of support layer B, adopt Illustrate as the situation of laminating method with coetrusion, but the present invention be not limited to such preparation method, it is also possible to The description below is that other form is prepared by reference similarly.Now, in the case of not containing extrusion operation, as long as Following " melt extruding temperature " is replaced with " melt temperature ".It should be noted that, herein by the fusing point of the polyester of use It is designated as Tm (unit: DEG C), glass transition temperature is designated as Tg (unit: DEG C).

First, as the polymer blend in order to form reflecting layer A, prepare polyester, void initiating agent and other appoint The compositions that meaning composition mixes.It addition, as in order to form the polymer blend supporting layer B, prepare polyester, inertia grain The compositions that son and other any composition mix.These polymer blends are dried and fully remove moisture and use.

Then, the polymer blend being dried is put into respectively to different extruders, melt extrudes.Melted crowded Go out temperature and need for more than Tm, as long as being set to about Tm+40 DEG C.

It addition, now for preparing the polymer blend of film, preferably using line especially for the polymer blend of reflecting layer A Footpath is that the non-woven fabric type filter that average pore size is 10 ~ 100 μm that the stainless steel filament of below 15 μm is made filters.Pass through Carry out this filtration, the most easily coagulation can be suppressed to form the coagulation 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 when melted by multilayer extrusion method (coetrusion) while using material feeding block (feed block) with many stratiforms State is extruded from die head, prepares unstretched layer stacks of sheets.The unstretched layer will extruded by die head by curtain coating drum (casting drum) Stacks of sheets cools and solidifies, and makes non-stretched stacked film.

Then, by roller heating, infrared heating etc. by this non-stretched stacked film heat, film forming machinery direction of principal axis (with Under have referred to as longitudinally, length direction or the situation of MD.) stretching obtain longitudinal stretching film.This 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 longitudinal direction and thickness direction To (having referred to as horizontal, width or the situation of TD below.) stretching, make biaxially-stretched film.

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

Herein, in the preparation of the white reflective film a of the present invention, the shape coating in order to make applicable inert particle State, it is preferred to use highly oriented stretching condition.Highly oriented stretching condition refers to be easily formed the stretching condition of high molecularly oriented, such as, make Elongating temperature step-down or the stretching condition making stretching ratio uprise or they being combined.Therefore, it is set to when low stretching ratio Low draft temperature condition, on the contrary high stretching ratio it is set to when high draft temperature, it is preferably set to such combination.

It addition, it is also preferred that use the draw speed of appropriateness.Its reason is, if draw speed is the slowest, then has resin to become The most lax trend, so there being the trend being difficult to form projection, has the trend of coating lower thickness；If it addition, draw speed mistake Hurry up, then have the trend that tensile stress uprises, so having easily by the trend in inert particle press-in support layer B, having coating thickness to become Thick trend.Specifically, as longitudinal draw speed, preferably 5 ~ 1000%/second, particularly preferably 200 ~ 500%/second. It addition, as horizontal draw speed, preferably 0.2 ~ 100%/second, particularly preferably 3 ~ 10%/second.

So, if the preparation method returning to white reflective film a or b of the present invention continues to record, then longitudinal direction is such as being implemented Stretching, then carry out cross directional stretch such the most biaxial stretch-formed time, preferably make the 2nd stage (in the case of Gai for cross directional stretch) compare The draft temperature in the 1st stage is high about 10 ~ 50 DEG C.Its reason is, by being orientated in the stretching in the 1st stage, as single shaft The Tg of film rises.

Additionally, it is preferred that film is preheated before each stretching.As long as the pre-heat treatment of such as cross directional stretch is from than polyester (preferably Constitute the polyester of reflecting layer A) the temperature of Tg+5 DEG C high start gradually to heat up.The intensification of cross directional stretch process can be continuous Or substep (successively), the most in turn heat up.Such as the regions of lateral stretch of stenter is divided into many along film moving direction Individual, heat up by flowing through the adding thermal medium of set point of temperature in each area.

Film after biaxial stretch-formed implements thermal finalization, heat-relaxing treatment and make Biaxially oriented film the most successively, squeezes from melted Going out until stretching, these process also can be carried out while film moves.

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

It addition, in order to adjust thermal shrinking quantity, two tip cut-offs of the film of holding can be adjusted the draw rate that film is longitudinal, make It is at longitudinal relaxation.As lax method, adjust the speed of the roller group of tenter outlet side.As lax ratio, relatively Film linear velocity in stenter carries out the reduction of speed of roller group, implements preferably 0.1 ~ 2.5%, further preferred 0.2 ~ 2.3%, particularly preferably The reduction of speed of 0.3 ~ 2.0%, thus by lax for film (this value is referred to as " relaxation rate "), adjust longitudinal heat by controlling relaxation rate Shrinkage factor.It addition, film laterally till by two tip cut-offs during width reduce, available desired percent thermal shrinkage.

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

The white reflective film of the so available present invention.

Finally, the recovery preparing closely-related film to the white reflective film b with the present invention especially illustrates.

[preparation from reclaiming raw material]

In the present invention, can use the white reflective film obtained by pulverizing, melt extrude obtained by material bits (chip) change Material, as certainly reclaiming raw material, makes an addition in film, preferably makes an addition to, in the A of reflecting layer, prepare white reflective as described above Film.Now, if as the white reflective film that film is the form possessing the present invention from the origin reclaiming raw material, even if then in system Standby will support that the agglutination particle in layer B is pulverized from reclaiming the operation of raw material or using it by the operation of film film forming, and make its Freshly prepd film contains, the reduction of the optical characteristics such as film property or reflectance does not the most occur, available good film property.Cause This, as the operation preparing this material bits, although there is no particular restriction, but considers mechanism as above, it is desirable to possesses pulverizer Structure, make containing agglutination particle pulverize as much as possible.Thus, recovery raw material certainly is being used to reuse as film raw material Time, it is possible to make the impact containing agglutination particle become less, obtain the more excellent white reflective films such as film property.

When being made an addition in film by such raw material of recovery certainly, on the basis of the quality that film is overall, it is preferably set to 5 ~ 50 matter Amount %, can make the raising effect of above-mentioned film property uprise.It addition, preferred form is for making an addition to support layer B and reflecting layer simultaneously Form in A, and substantially make an addition to the form in the A of reflecting layer without in support layer B.In this case, with On the basis of the quality of reflecting layer A, reflecting layer A is preferably set to 10 ~ 70 mass % from the content reclaiming raw material, the raising of film property Effect is more excellent.It should be noted that, although also can certainly reclaim raw material to supporting layer B adds, but particularly preferably will be former from reclaiming Material is substantially not used in support layer B for reflecting layer A.By making such form, not only can maintain good film property, Reflectance, and superficiality and the production capacity of excellence of the stickup of suppression and light guide plate can be obtained, it is advantageous to.

Embodiment

Describe the present invention the most in detail.It should be noted that, each characteristic value measures using the following method.

(A) for embodiment 1 ~ 17 and comparative example 1,4,6,9,11, assay method with reference to comparative example 5,7,10

(1) light reflectance

Integrating sphere installed by spectrophotometer (Shimadzu Seisakusho Ltd. UV-3101PC), measures BaSO under 550nm wavelength₄ The albedometer of blank is reflectance when 100%, using this value as reflectance.It should be noted that, measure and supporting layer B side Surface is carried out.In the case of table, the back of the body have different support layer B, it is measured on the support layer surface of light guide plate side.

(2) mean diameter of void initiating agent (inorganic particulate)

With particle size distribution meter (hole field makes made LA-950), try to achieve the particle size distribution of particle, by d₅₀Particle diameter as average particle Footpath.

(3) volatile organic solvent amount

Under room temperature (23 DEG C), the membrane sample of 1g is put into the fluororesin bag of 10L, will wherein purge and close with purity nitrogen Envelope.Then, the nitrogen of 0.2L, 1.0L is gathered to 2 analysis use with the flow nitrogen from such bag respectively of 0.2/ minute immediately In TENAX-TA trap tube, use them, by HPLC and GCMS, the matter to Elements in Organic Solvents contained in the nitrogen gathered Amount is carried out quantitatively.The value obtained is scaled the amount in 10L nitrogen, and that tries to achieve that the membrane sample from 1g evaporates into the nitrogen of 10L is organic The quality of solvent, as volatile organic solvent amount (unit: ppm, on the basis of the quality of membrane sample).It should be noted that, about Aldehydes, with acetonitrile by aldehyde derivatives from trap tube dissolution, and is carried out quantitatively by HPLC.It addition, HPLC Yu GCMS value not In the case of Tong, use the value of more detection one side.

It should be noted that, for embodiment 10 ~ 18 and comparative example 6,9,11, with reference to comparative example 5,7,10, will volatilize organic Quantity of solvent is that the situation of below 10ppm is evaluated as zero, the situation more than 10ppm is evaluated as ×.

(4) film thickness and Rotating fields

With microtome, white reflective film is cut into slices, carry out exposing of cross section, use Hitachi S-4700 type Flied emission Such cross section is observed under the multiplying power of 500 times by type scanning electron microscope, tries to achieve film entirety, reflecting layer A respectively, props up Hold the thickness of layer B.It should be noted that, film is overall and supports that the thickness of layer B is set to eliminate agglutination particle or inert particle from propping up Hold the thickness of the part of the prominent part in layer surface.The thickness ratio of each layer is calculated afterwards at the thickness (μm) trying to achieve each layer.

(5) calculating of voidage rate

As requested space volume fraction layer polymer, add particle, other the density of each composition is asked with mixing proportion Density must be calculated.Meanwhile, this layer is carried out stripping etc. thus separates, quality measurement and volume, calculate actual density according to them, Tried to achieve by following formula according to calculating density and actual density.

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。

It addition, the layer of only separation determination voidage rate, try to achieve the quality of per unit volume thus try to achieve actual density.Just For volume, sample is cut 3cm²Area, 10 will be measured with electronic gauge (Anritsu (ア Application リ Star) K-402B processed) Obtained by thickness under this size of individual point, meansigma methods is as thickness, calculates with area × thickness.Quality electronic balance Weigh.

It should be noted that, as the proportion of agglutination particle, use the value of the bulk specific gravity tried to achieve by following graduated cylinder method.To Volume be 1000ml graduated cylinder in fill the agglutination particle of absolute dry condition, measure overall weight, by the weight of this entirety Deduct the weight of graduated cylinder thus try to achieve the weight of this agglutination particle, measure the volume of this graduated cylinder, by with the weight of this agglutination particle Amount (g) is divided by this volume (cm³) try to achieve.

(6) fusing point, glass transition temperature

Use Differential Scanning Calorimetry determinator (TA Instruments 2100 DSC), enter with the programming rate of 20 DEG C/min Row measures.

(7) ten mean roughness (Rz)

With three-dimensional roughness determinator SE-3CKT (strain formula can little slope research made), at the cutoff of 0.25mm, 1mm The projection scattergram (profile) on film surface is measured under measured length, the sweep span of 2 μm, the scan stripes number of 100, Projection scattergram is recorded under the height multiplying power of 1000 times, the scanning direction multiplying power of 200 times.In the projection scattergram obtained, from The side that peak (Hp) is high takes 5 points, takes 5 points from the side that paddy (Hv) is low, by following formula try to achieve 10 mean roughness (Rz, Unit: nm).It should be noted that, use three-dimensional roughness resolver SPA-11 (Kosaka Laboratory Ltd. in parsing System).

It addition, according to the projection scattergram (transverse axis: rising height, the longitudinal axis: the projection scattergram of projection number) obtained, ask Must be highly the projection number (individual/m of more than 5 μm²), 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, the one end at handle portion (1) pastes the ferrum of length 200mm × width 200mm × thickness 3mm securely Plate (2, weight is about 200g), thereon, pastes with reflectance coating that evaluation face is above width 250mm × length 200mm (3), making the two ends of width the part of each 25mm from iron plate stretch out (make central authorities 200mm × 200mm part with Iron plate is overlapping).Now, the evaluation face (support aspect) making reflectance coating becomes outside.It addition, by the width at reflectance coating The partially folded dorsal part to iron plate of the 25mm that two ends are unnecessary, blade (is inserted because of cutter etc. during sampling in the end getting rid of reflectance coating Part) impact of scraping light guide plate.

Then, by with have the some face of point (401) be above light guide plate (4, leading of the size of at least 400mm × 200mm Tabula rasa) it is fixed on the desk of level, the produced above reflectance coating being fixed on iron plate is put with facing down to of reflectance coating side Put on light guide plate, make evaluation face contact with light guide plate, and then place the counterweight (5) of 500g thereon, with the distance of 200mm (making the mobile reflectance coating being fixed on iron plate in the region of 400mm × 200mm) comes and goes with the speed that 1 time comes and goes about 5 ~ 10 seconds Mobile 15 times.Then, in light guide plate surface, use the magnifier of 20 times for its scraping situation and the particle that comes off from reflectance coating Presence or absence observe, be evaluated according to following benchmark.

Rubbed 400mm × 200mm on light guide plate all in the range of, puts without available after reciprocating 15 times 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 have the situation of observable damage to be designated as " difficult scraping " (scraping is evaluated as △), past after reciprocating 15 times The situation of observable damage is had to be designated as " scraping " (scraping be evaluated as ×) after returning mobile 10 times.

It addition, after reciprocating 15 times, the rubbed 400mm × 200mm on light guide plate all in the range of, if The white foreign matter observed without available magnifier, then be designated as " particle does not falls off " (come off and be evaluated as zero).It addition, there is being observable During the white foreign matter arrived, by the such white foreign matter of microscopic, if confirming as inert particle (agglutination particle), and come off Particle be less than 5, then be designated as " particle does not almost fall 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, the impact of inhibition point size should be done one's utmost, in light guide plate, do one's utmost choosing Select the region that spot size is big, as one man carry out in each evaluation sample.

(9) adhesion plaque evaluation (is pasted and is evaluated)

Take out casing (6) from LG company LED liquid crystal television machine (LG42LE5310AKR), be placed on the desk of level, make electricity Depending on machine private side upward, place the reflectance coating of size almost identical with casing thereon, make support aspect upward, and then thereon Place light guide plate and 3 optical sheets (diffusion barrier 2,1, prism) (7) that television set was possessed originally.Then, in its face In, in the region of concavo-convex the most violent part comprising casing, place the circle possessing three a diameter of 5mm as illustrated in fig. 2 Equilateral triangle type pedestal (801) of shape lower limb, places the counterweight (802) of 15kg the most further, such by visualization Three lower limb areas encompassed, if bright part without exception, are then designated as " without adhesion plaque " (adhesion plaque is evaluated as zero).It addition, In the case of having abnormal bright part, 3 optical sheets are placed DBEF sheet that television set was possessed originally further Material, likewise by being visually observed, if abnormal bright part not restored, is then designated as " having adhesion plaque " and (is evaluated as ×), if no longer there being abnormal bright part, then it is designated as " almost without adhesion plaque " (being evaluated as △).It should be noted that, three lower limb institutes The region surrounded is set to the approximation equilateral triangle of a length of 10cm on each limit.

(B) for embodiment 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, use solvent dissolving resin composition, the particle thus reclaimed (secondary grain Son) use S-4700 type field emission type scanning electron microscope in Hitachi to observe under the multiplying power of 1000 times, observe two Any 100 primary particles are carried out particle size determination, ask according to its meansigma methods by the coagulation situation of the primary particle of secondary particle surface Obtain primary particle size (dp).

In the above-mentioned methods, when by solvent dissolving resin composition, agglutination particle is (the most organic in the case of also dissolving In the case of particle), use the agglutination particle before blending, use S-4700 type field emission type scanning electron in Hitachi to show Micro mirror, observes under the multiplying power of 10000 times, observes the coagulation situation of the primary particle on offspring surface, to any 100 Individual primary particle carries out particle size determination, tries to achieve primary particle size (dp) according to its meansigma methods.

Less than the situation of 3 μm, 1 μm is designated as " ＜ 3 ", and 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, use solvent dissolving resin composition, the particle thus reclaimed (secondary grain Son) use S-4700 type field emission type scanning electron microscope in Hitachi to observe under the multiplying power of 1000 times, to arbitrarily 100 particles carry out particle size determination, try to achieve aggregate particle size (ds) according to its meansigma methods.It should be noted that, the feelings beyond spherical Tried to achieve by (major diameter+minor axis)/2 under condition.Herein, minor axis refers to and the maximum gauge of major diameter vertical direction.

In the above-mentioned methods, when by solvent dissolving resin composition, agglutination particle is (the most organic in the case of also dissolving In the case of particle), use the agglutination particle before blending, use S-4700 type field emission type scanning electron in Hitachi to show Micro mirror, observes under the multiplying power of 1000 times, measures the particle diameter of 100 particles, tries to achieve aggregate particle size according to its meansigma methods (ds).It should be noted that, tried to achieve by (major diameter+minor axis)/2 in the case of there is major diameter and minor axis.Herein, minor axis refers to long The maximum gauge of footpath vertical direction.

(12) brightness

Take out reflectance coating from LG company LED liquid crystal television machine (LG42LE5310AKR), be arranged at various reflectance coating and (will support Layer side, as on picture side (face being connected with light guide plate), uses luminance meter (big tomb electronics system when back light unit Model MC-940), the center of backlight is measured brightness from dead ahead under the mensuration distance of 500mm.

(13) white point evaluation

Use the reflectance coating and light guide plate used in the evaluation of above-mentioned (8), to make the supine mode of support layer on desk Place reflectance coating, thereon to make a little ventricumbent mode place light guide plate, place respectively on four limits of light guide plate and fixing each The counterweight of 200g, uses the back light of LG company LED liquid crystal television machine (LG42LE5310AKR), from the side of light guide plate Incident illumination, if there being the bright point beyond the light guide plate point that can pass through to be visually observed, then is designated as producing white point (being evaluated as ×). On the other hand, if then can not be designated as not producing white point (being evaluated as zero) by the bright point of the exception that is visually observed.

(14) film forming draftability

Observe by use the continuous film forming method of stenter by film forming stability during film film forming described in embodiment, according to Lower benchmark is evaluated.

◎: can stably film forming more than 3 hours.

Zero: can stably film forming more than 1 hour.

△: occurred 1 time to cut off in 1 hour.

×: occurred repeatedly to cut off within 1 hour, it is impossible to stably film forming.

(C) for embodiment 10 ~ 18 and comparative example 6,9,11, with reference to comparative example 5,7,10

(15) the coating thickness of inert particle

Use microtome, cut section sample from the film of epoxy resin embedding.Now, notice that the direction etc. inserting blade is not so that Projection is crushed.For the section of section sample, use Hitachi S-4700 type field emission type scanning electron microscopy Mirror, observes under the multiplying power of 3000 times.

100 particle sections are taken pictures, as it is shown on figure 3, draw the horizontal line (a) on film surface in photo and (a) puts down Capablely by the straight line (b) on projection summit and (a) parallel through the straight line (c) of the particle topmost in projection, according to (b) C the thickness (d) of the resin-coated part of the measuring space projection apex of (), using its meansigma methods as the coating thickness of 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 (all acid compositions relative to the polyester obtained 100 moles of % are 9 moles of %) dimethyl isophthalate, the ethylene glycol of 98 mass parts, the diethylene glycol of 1.0 mass parts, 0.05 matter The amount manganese acetate of part, the lithium acetate of 0.012 mass parts load in the flask possessing rectifying column, distiller condenser, add while stirring Methanol is distilled by heat to 150 ~ 240 DEG C, carries out ester exchange reaction.After being distilled by methanol, add the phosphoric acid of 0.03 mass parts Trimethyl, the germanium dioxide of 0.04 mass parts, be transferred to reactant in reactor.Then, the most gradually will react It is warming up to 292 DEG C while being decompressed to 0.3mmHg in device, carries out polycondensation reaction, obtain the poly-terephthaldehyde of M-phthalic acid copolymerization Acid glycol ester 1.The fusing point of this polymer is 235 DEG C.

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

Be changed to the dimethyl terephthalate (DMT) of 129.0 mass parts, 21.0 mass parts (become relative to all acid of the polyester obtained Point 100 moles of % are 14 moles of %) dimethyl isophthalate, in addition, obtain isophthalic two in the same manner as above-mentioned preparation example 1 Formic acid copolymerization polyethylene terephthalate 2.The fusing point of this polymer is 215 DEG C.

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

Be changed to the dimethyl terephthalate (DMT) of 142.5 mass parts, 7.5 mass parts (become relative to all acid of the polyester obtained Point 100 moles of % are 5 moles of %) dimethyl isophthalate, in addition, obtain isophthalic two in the same manner as above-mentioned preparation example 1 Formic acid copolymerization polyethylene terephthalate 3.The fusing point of this polymer is 245 DEG C.

Preparation example 4: the preparation of organic agglutination particle

Raw material described below loading in autoclave, heats 120 minutes in 180 ~ 240 DEG C, carries out ester exchange reaction.Connect , reaction system is warming up to 245 DEG C, pressure in system is set to 1 ~ 10mmHg, continue the reaction of 60 minutes, thus be total to Polyester.

Dimethyl terephthalate (DMT) 134 mass parts

Dimethyl isophthalate 5 mass parts

5-sodium sulfonate dimethyl isophthalate 3 mass parts

P-tert-butyl benzoic acid methyl ester 5 mass parts

Ethylene glycol 136 mass parts

Four titanium butoxide acid esters 0.1 mass parts

The slow coagulation of resin that will obtain, obtains organic agglutination particle (coagulation polyester granules).

Preparation example 5: the preparation of particle masterbatch bits 1

Use a part for the M-phthalic acid copolymerization polyethylene terephthalate 1 as above obtained, and use average particle Footpath is that the barium sulfate particles of 1.0 μm (is labeled as BaSO in table₄.) as void initiating agent, go here and there with society of Kobe Steel NEX-T60 Connection formula extruder, so that the content of barium sulfate particles is 63 mass % relative to the quality of masterbatch bits (master chip) obtained Mode mix, extrude under the resin temperature of 260 DEG C, preparation containing barium sulfate particles inorganic particulate masterbatch bits 1。

Preparation example 6: the preparation of particle masterbatch bits 2

In the M-phthalic acid copolymerization polyethylene terephthalate 2 as above obtained, as coagulation silicon dioxide granule A, Mixing Tosoh Silica Corporation (ソシリカ Co., Ltd.) AY-603 processed is 8 mass %, Extrude under the melt temperature of 235 DEG C, prepare inorganic particulate masterbatch bits 2.

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

In the M-phthalic acid copolymerization polyethylene terephthalate 3 as above obtained, add inert particle as shown in table 1 And be mixed to into content as shown in table 1, extrude under the melt temperature of 235 DEG C, prepare particle masterbatch bits 3 ~ 10。

Table 1

It should be noted that, use organic siliconresin company of SHIN-ETSU HANTOTAI KMP series as organic siliconresin particle, as acrylic acid tree Fat granule uses hydrops chemical conversion product society MBX series.

Preparation example 15: the preparation of particle masterbatch bits 11

In the polyethylene terephthalate 2 of the copolymerization M-phthalic acid as above obtained, it is added on and preparation example 4 obtains Coagulation polyester granules also carries out mixing so that its content is 15 mass %, extrudes, prepare grain under the melt temperature of 235 DEG C Primary and secondary material bits 11.

Embodiment 1

(preparation of white reflective film)

Consider M-phthalic acid copolymerization polyethylene terephthalate 1 obtained above and particle masterbatch to be worth doing 1 and be used as reflecting layer (A Layer) raw material, M-phthalic acid copolymerization polyethylene terephthalate 2 and particle masterbatch are considered to be worth doing 2 and are used as to support layer (B layer) Raw material, to make each layer mix for the mode of the composition described in table 2, puts in extruder, and A layer squeezes 255 DEG C melt At a temperature of going out, B layer, at a temperature of 230 DEG C melt extrude, uses 3 layers of material feeding block device to collaborate, to be formed as shown in table 2 The Rotating fields of B layer/A layer/B layer, keep this laminated arrangement to be directly shaped to lamellar by die head.Now, each extruder is adjusted Output, so that the thickness of B layer/A layer/B layer is 10/80/10 than after biaxial stretch-formed.And then by this sheet material surface temperature be The drum cooler of 25 DEG C makes the unstretching film of cooling and solidifying.By this unstretching film by the preheating zone of 73 DEG C, then pass through 75 DEG C Preheating zone, import and remain the longitudinal stretching district of 92 DEG C, be longitudinally stretched to 2.9 times, cooling down by the roller group of 25 DEG C.Connect , pass through the preheating zone of 115 DEG C while fixing at the two ends of film clip, import the cross directional stretch district remaining 130 DEG C, Cross directional stretch is to 3.6 times.Then, in stenter, carry out thermal finalization in 185 DEG C, with 2% subtract wide rate 130 DEG C subtract wide temperature Carry out under degree horizontal subtracting width (width enters れ), then by film two tip cut-off, carry out hot wire-CVD with the longitudinal relaxation rate of 2%, be cooled to Room temperature, obtains the biaxially-stretched film that thickness is 250 μm as shown in table 2.

This film is reclaimed and pulverizes, carries out melt extruding and expect bitsization thus preparation is from reclaiming raw material, with the matter of reflecting layer A On the basis of amount, adding the such from reclaiming raw material of 35 mass % in the A of reflecting layer, obtaining thickness as described above is 250 μm Biaxially-stretched film, obtain white reflective film.The evaluation result of the film obtained is illustrated in table 3.

Embodiment 2

Coagulation silicon dioxide granule A is changed to coagulation silicon dioxide granule B (Grace Japan Co., Ltd. (グレスジャパ Application Co., Ltd.) C812 processed), in addition, prepare biaxially-stretched film and former from reclaiming similarly to Example 1 Material, uses them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Embodiment 3

Coagulation silicon dioxide granule A is changed to coagulation silicon dioxide granule C (by Fuji Silysia Chemical Ltd. (Fuji シリシア KCC) Cariact processed (キャリア Network ト) P-10 air classifier removes more than 30 μm And the powder body obtained), in addition, prepare biaxially-stretched film similarly to Example 1 and certainly reclaim raw material, using them to prepare White reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Embodiment 4

Coagulation silicon dioxide granule A is changed to coagulation silicon dioxide granule D (Fuji Silysia Chemical Ltd. (Fuji シリシア KCC) Cariact processed (キャリア Network ト) P-10), in addition, similarly to Example 1 Ground is prepared biaxially-stretched film and certainly reclaims raw material, uses them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated In table 3.

Embodiment 5

(preparation of white reflective film)

By particle masterbatch bits 2 be changed to particle masterbatch bits 11, in addition, prepare similarly to Example 1 biaxially-stretched film and From reclaiming raw material, them are used to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Embodiment 6

The void initiating agent of reflecting layer A is changed to as shown in table 2 the resin incompatible with polyester (cycloolefin, Polyplastics Co., Ltd. system " TOPAS 6017S-04 "), in addition, prepare twin shaft similarly to Example 1 and draw Stretch film and certainly reclaim raw material, using them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Embodiment 7,8

The addition of coagulation silicon dioxide granule A is set to as shown in table 2, in addition, prepares twin shaft similarly to Example 1 Stretched film and certainly reclaim raw material, uses them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Embodiment 9

Change the form of preparation condition, Rotating fields as shown in table 2, in addition, prepare biaxial stretch-formed similarly to Example 1 Film and certainly reclaim raw material, uses them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Comparative example 1

In the support layer B of embodiment 1, do not add agglutination particle (use M-phthalic acid copolymerization polyethylene terephthalate 2 replace particle masterbatch bits 2.And, using such layer as surface layer C.), in addition, preparing similarly to Example 1 After thickness is the biaxially-stretched film of 250 μm, in the one side of this film, it is coated with by shown in following tune formula of liquid 1 with die head apparatus for coating Composition constitute coating fluid, in baking oven in 80 DEG C be dried thus formed support layer B, obtain film.Such support layer B Dry thickness be 2 μm.Then, this film reclaimed and pulverize, carrying out melt extruding and expect bitsization thus prepare certainly to reclaim raw material, They add on the basis of the quality of reflecting layer A in the A of reflecting layer 35 mass % use, taste the most as described above The film forming of examination film, but when by film film forming, produce the foreign body such as non-fused mass, gas trace in a large number, draftability is greatly reduced, so cannot Gather sample.

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

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

Acryloid cement: DIC Acrydic (ア Network リディッ Network) A-817BA 17.5 mass %

Cross-linking agent: Japanese polyurethane industry society Koronate (U ロネト) HL 11.7 mass %

Organic solvent: butyl acetate 53.2 mass %

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

Particle: 50 mass %

Binding agent: 25 mass %

Cross-linking agent: 25 mass %.

Comparative example 2

Coagulation silicon dioxide granule A is changed to coagulation silicon dioxide granule E (Tosoh Silica Corporation ( ソシリカ Co., Ltd.) BY601 processed), in addition, prepare biaxially-stretched film and former from reclaiming similarly to Example 1 Material, uses them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in table 3.

Comparative example 3

Coagulation silicon dioxide granule A is changed to coagulation silicon dioxide granule F (Fuji Silysia Chemical Ltd. (Fuji シリシア KCC) Sylysia processed (サイリシア) 350), in addition, similarly to Example 1 Prepare biaxially-stretched film and certainly reclaim raw material, using them to prepare white reflective film, implementation evaluation.Evaluation result is illustrated in In table 3.

Comparative example 4

Coagulation silicon dioxide granule A is changed to spherical silicon dioxide particle (marshy land KCC Silton (シ Le ト Application) JC), in addition, prepare biaxially-stretched film similarly to Example 1 and certainly reclaim raw material, using they preparation whites anti- Penetrating property film, implementation evaluation.Evaluation result is illustrated in table 3.

From above-described embodiment 1 ~ 9, according to the present invention, it is possible to provide: can fully suppress the stickup with light guide plate, meanwhile, Even if reclamation film also is used as preparing film from reclaiming raw material, the callable white reflective film that film property is still excellent.

Embodiment 10

(preparation of white reflective film)

M-phthalic acid copolymerization polyethylene terephthalate 1 obtained above and particle masterbatch are considered 1 to be worth doing as reflecting layer (A Layer) raw material, carry out mixing so that the content of barium sulfate is 45 weight % uses, on the other hand, M-phthalic acid copolymerization gathered Ethylene glycol terephthalate 3 and particle masterbatch bits 3, as the raw material of support layer (B layer), carry out mixing to become described in table 4 Content and use, put in extruder, use 3 layers of material feeding block device to collaborate, to form the layer knot of B layer/A layer/B layer Structure, keeps this laminated arrangement to be directly shaped to lamellar by die head.Now, adjust the output of each extruder, so that B layer/A layer/B The thickness of layer becomes 10/80/10 than after biaxial stretch-formed.And then the drum cooler that this sheet material surface temperature is 25 DEG C is made cold But the unstretching film solidified.This unstretching film is imported induction heating roller group and is preheated to 73 DEG C, then limit using up and down from film So that film surface temperature becomes 95 DEG C between 2 groups of rolls of infra-red light irradiation, while before and after utilizing with the draw speed of 350%/second The difference of roller is being longitudinally stretched to 2.9 times, cools down by the roller group of 25 DEG C.Then, solid with clip at the two ends of film By the preheating zone of 95 DEG C while Ding, import the cross directional stretch district remaining 110 DEG C, expand the interval of clip so that stretching is fast Degree is 5.8%/second, at cross directional stretch to 3.6 times.Then, in stenter, carry out thermal finalization in 185 DEG C, exist with the wide rate that subtracts of 2% 130 DEG C subtract carries out at wide temperature horizontal subtracting width, then by film two tip cut-off, carries out hot wire-CVD with the longitudinal relaxation rate of 2%, It is cooled to room temperature, obtains the biaxially-stretched film that thickness is 250 μm.The evaluation result of the film obtained is illustrated in table 4.

Embodiment 11 ~ 18, comparative example 6,9,11, with reference to comparative example 5,7,10

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

From above-described embodiment 10 ~ 18, according to the present invention, it is possible to provide suppress the damage of light guide plate and suppress particle to come off White reflective film.

Industrial applicability

The white reflective film of the present invention suppresses the damage of light guide plate and suppresses particle to come off, even if using recovery raw material certainly the most difficult Reduce the film property of film, so the area source reflecting plate possessing light guide plate can be especially suitable for use as, wherein, can be suitable as such as For such reflectance coatings for side light type backlight unit such as liquid crystal indicators.

Claims

1. a white reflective film, described white reflective film has reflecting layer A and supports that layer B, described support layer B are by poly- The polyester and resin composition comprising the inert particle that mean diameter (d) is below more than 2 μm 75 μm in ester resin is formed,

2. the white reflective film of claim 1, wherein, supports at 10 of the surface with A opposition side, reflecting layer of layer B the most slightly Rugosity (Rz) is less than 5 μm.

3. the white reflective film of claim 1 or 2, wherein, on the basis of the volume supporting layer B, supports the inertia grain in layer B The content of son is 0.1 ~ 20 volume %.

4. the white reflective film any one of claim 1 ~ 3, wherein, the mean diameter (d) of the inert particle in support layer B Following formula (1) is met with the thickness (t) supporting layer B:

0.2≤d(μm)/t(μm)≤2.5···(1)。

5. the white reflective film any one of claim 1 ~ 4, wherein, volatile organic solvent amount is below 10ppm.

6. the white reflective film any one of claim 1 ~ 5, it is used as edge-lit backlight unit reflecting plate.