KR20170086218A - Pet bead for preventing blocking, manufacturing method thereof, reflective film and light source assembly - Google Patents

Abstract

The present invention relates to a PET bead which is softer than PMMA beads and PBMA beads, has better blocking effect than PE beads, and has a large effect of preventing white spots and scratches, a process for producing the same, a reflective film coated with the PET beads, To a light source assembly.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a PET bead for preventing blocking, a production method thereof, a reflective film and a light source assembly,

The present invention relates to a PET bead for preventing blocking, a method for producing the same, a reflective film, and a light source assembly, and more particularly, to a PET bead for preventing blocking, which is softer than polymethyl methacrylate (PMMA) beads and polybutyl methacrylate The present invention relates to a PET bead having a blocking effect rather than a PE bead and having a large effect of preventing white spots and scratches, a method for producing the PET bead, a reflective film coated with PET beads, and a reflective film.

In recent years, LED (Light Emitting Diode) has been used as a light source of a backlight unit for reducing the thickness and power consumption of a liquid crystal display device. In a so-called edge type backlight unit in which a double LED light source is disposed on the side of a liquid crystal display device, A reflective film is disposed, and a light guide plate and a light diffusion film are disposed thereon to constitute a backlight unit.

However, edge type displays such as the above-mentioned edge type backlight unit and the like are likely to come into contact with the reflective film because the light source is located only at the edge portion, which is a major cause of white point.

Therefore, in order to solve the above problems, the antiblocking agent mainly used is PMMA bead (Korean Patent Laid-Open No. 10-2010-0130045), PBMA bead (Korean Patent Laid-Open Publication No. 10-2012-0136894) This is a problem in that scratches (scratches) due to vibration are likely to occur due to the same material as the doping plate.

On the other hand, when soft polyethylene (PE) beads are used, there is a problem that a white point is generated due to a pressing phenomenon due to impact.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a PET bead which is softer than PMMA beads and PBMA beads, has better blocking effect than PE beads, .

Another object of the present invention is to provide a method for producing the PET beads.

It is still another object of the present invention to provide a reflective film comprising the PET beads.

It is still another object of the present invention to provide a light source assembly including the reflective film.

In order to achieve the above object, the present invention provides a polyethylene terephthalate (PET) of the following general formula (1): polyethylene terephthalate represented by the following general formula (2) wherein a part of terephthalic acid (TPA) is substituted with isophthalic acid (PET) represented by the following formula (3) in which a part of ethylene glycol (EG) is substituted with neopentyl glycol (NPG) and copolymerized with polyethylene terephthalate (PET) A PET bead for preventing blocking is provided.

[Chemical Formula 1]

(2)

(3)

(In the above formulas (1) to (3), m and n are independently integers of 1 to 1000.) In addition, the present invention relates to a process for producing a PET bead by pulverizing a polyethylene terephthalate (PET) chip, PET of Formula 2 in which a part of terephthalic acid is replaced with isophthalic acid or PET of Formula 1 wherein PET is PET of Formula 3 in which a part of ethylene glycol is substituted with neopentyl glycol, And a manufacturing method thereof.

The present invention also provides a reflective film comprising a base film and anti-blocking beads coated on either side of the base film, wherein the anti-blocking beads are the PET beads.

In addition, the present invention provides a light source assembly including a light source, a light guide plate for reflecting incident light from the light source, and a reflective film disposed on a surface facing the light guide plate.

According to the present invention, it is possible to solve the problem of the white point of the edge type display such as the edge type backlight unit by preventing the blocking efficiently, and to provide the anti-blocking PET bead excellent in scratch resistance, the reflective film using the PET bead, A light source assembly can be provided.

The present invention relates to a polyethylene terephthalate (PET) represented by the following formula (2) or a polyethylene terephthalate (PET) represented by the following formula (1) in which a part of terephthalic acid is substituted with isophthalic acid in polyethylene terephthalate (PET) in which a part of ethylene glycol is substituted with neopentyl glycol and is copolymerized with polyethylene terephthalate (PET).

[Chemical Formula 1]

(2)

(3)

(In the above formulas (1) to (3), m and n are independently an integer of 1 to 1000)

In the anti-blocking PET bead of the present invention, the number average molecular weight of Formula 1 is preferably 30,000 to 40,000 and the weight average molecular weight is preferably 40,000 to 50,000.

In the anti-blocking PET bead of the present invention, the number average molecular weight of Formula 2 is preferably 20,000 to 30,000 and the weight average molecular weight is preferably 30,000 to 40,000.

In the anti-blocking PET bead of the present invention, the number average molecular weight of Formula 3 is preferably 35,000 to 45,000 and the weight average molecular weight is preferably 45,000 to 60,000.

PET (polyethylene terephthalate) is a thermoplastic plastic that is one of polyester polymers and is widely used as case and packaging materials for drinking bottles (PET bottles), household goods, toys, electric insulators, (methylmethacrylate) and PBMA (poly (butylmethacrylate)).

In the anti-blocking PET bead of the present invention, the content of the copolymerized isophthalic acid or neopentyl glycol may be 0.6 to 14 mol%, preferably 1 to 10 mol%.

The present invention also relates to a method for producing a PET bead by pulverizing a polyethylene terephthalate (PET) chip, wherein the PET chip is a PET of the formula (2) in which a part of the terephthalic acid is substituted with isophthalic acid, Or PET of Formula (1) wherein PET is substituted with neopentyl glycol in part of ethylene glycol.

In the method for producing PET beads of the present invention, PET beads can be prepared by pulverizing the PET chips in a frozen state.

In the method of manufacturing PET beads of the present invention, the PET chips may be frozen using liquid nitrogen as a refrigerant.

Since PET is a thermoplastic resin, it has a property of being melted and adsorbed by thermal deformation, general pulverization is difficult, and a method of grinding a PET chip with a bar type rotor in a liquid nitrogen atmosphere is adopted.

The method of manufacturing PET beads of the present invention may further include a sphering process of sphering the outer circumferential surface of the PET bead.

The present invention also relates to a base film and a reflection film comprising anti-blocking beads coated on either side of the base film, wherein the anti-blocking beads are the PET beads.

The reflective film of the present invention is a blocking bead for a reflective film, and the PET bead may be coated on the base film to produce a reflective film.

In the reflective film of the present invention, as the base film, a transparent film capable of transmitting light is used, and examples thereof include, but are not limited to, polycarbonate, polyacrylate, polystyrene, A known polymer film such as a chloride-based film can be used.

In the reflective film of the present invention, the coating of the PET beads on the base film uses one or two or more transparent binder resins selected from the group consisting of acrylic, epoxy, vinyl, polyester and polyamide polymers, This makes it possible to prevent the bead particles from falling off from the base film.

In addition, if necessary, inorganic pigment particles and the like may be coated together with the PET beads and the binder resin, and a reflective film can be obtained by coating them. Since the coating method is well known in the art, detailed description is omitted here.

In addition, the present invention relates to a light source, a light guide plate for reflecting incoming light from the light source into the inside, and a light source assembly disposed on a surface facing the light guide plate and including the reflection film.

The light source assembly of the present invention may be a reflective film for a light source assembly, and the reflective film may be provided on one side of the light guide plate.

The light source assembly of the present invention can be used as a backlight unit of a display device using, for example, an LED as a light source for backlight. The light source assembly includes a light source that is made of, for example, an LED and emits light, And a light guide plate disposed on the top of the reflective film and reflecting light incident from the light source to the inside, and may further include a diffusion film and a prism, if necessary. Since these structures are well-known structures, detailed description is omitted here.

In addition, the light source assembly of the present invention is not limited to the above structure, and any known structure may be used as long as it uses a reflection film and a light guide plate. Importantly, the light source assembly of the present invention, Any structure may be used as long as it is a light source assembly including a film.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the present invention is not limited to the following examples.

≪ Examples and Comparative Examples &

In the following Examples 1 to 6 and Comparative Examples 1 to 6, PET beads were prepared by freeze-pulverization of PET chips, liquid nitrogen was used as a medium for freezing PET chips, and the freezing temperature Was performed within a range of about -20 캜 to -70 캜.

As the grinding machine for freezing and grinding, a well-known freezing grinder was used. As the grinding PET chip, a PET chip cut to a size of about 2.0 x 3.0 mm was used. The grinding conditions were grinding rpm at 3,500 rpm , And the feed rate of the PET chips supplied into the feeder of the freeze-crusher was 75 kg / h.

On the other hand, the PET used in the following Examples 1 to 6 and Comparative Examples 1 to 6 has a number average molecular weight of 20,000 to 40,000 and a weight average molecular weight of 30,000 to 60,000. The molecular weight was measured by gel permeation chromatography (GPC) (GPC Autochro) using a standard polystyrene reduced weight average molecular weight and number average molecular weight.

The polymer to be measured was dissolved in hexafluoroisopropanol so as to have a concentration of 0.1 wt%, and 500 ul was injected into GPC. The mobile phase of GPC was flowed at a flow rate of 1.0 mL / min using hexafluoroisopropanol and analysis was performed at 40 < 0 > C.

At this time, two columns of guard columns and one 5 μl mixed-D of PL were connected in series. In addition, the detector was measured using a 410 RI detector.

≪ Comparative Example 1 &

PET beads were prepared by grinding PET chips with a bar type rotor in a liquid nitrogen atmosphere using a PET homopolymer of the following formula (1) as PET chips.

The PET homopolymer has high heat resistance compared with general-purpose PET, and is widely used as a container molding injection molding and sheet molding material requiring high temperature, and has excellent strength and durability. The PET used herein had a number average molecular weight of 32,210 and a weight average molecular weight of 44,127.

[Chemical Formula 1]

≪ Comparative Example 2 &

PET beads were prepared in the same manner as in Comparative Example 1, except that a PET chip of Formula 2 was used which was copolymerized with 0.5 mol% of isophthalic acid (IPA) in terephthalic acid (TPA) as a raw material.

Since the IPA is copolymerized with the linear TPA by chain bending, the IPA has a soft characteristic as the content is higher. The PET used herein had a number average molecular weight of 23,750 and a weight average molecular weight of 36,292.

(2)

≪ Comparative Example 3 &

PET beads were prepared in the same manner as in Comparative Example 1, except that a PET chip of Formula 3, which was copolymerized by adding 0.5 mol% of neopentyl glycol (NPG) to ethylene glycol (EG) as a raw material, was used.

Since the methyl group is formed as a side chain in the NPG, the distance between the molecular chains is increased and the flow distance is increased to provide a more soft effect. The PET used herein had a number average molecular weight of 38,432 and a weight average molecular weight of 51,657.

(3)

≪ Comparative Example 4 &

PET beads were prepared in the same manner as in Comparative Example 1, except that the PET chips of the following formula (4) were used in which 0.5 mol% of cyclohexanedimethanol (CHDM) was added to ethylene glycol (EG) as a raw material.

Since the PET chip has soft properties because it is difficult to crystallize, it is possible to alleviate the chipping phenomenon, but on the other hand, the PET chip is copolymerized with the benzene ring structure, so that the chipping phenomenon can be further amplified. Also, due to the copolymerized benzene ring, the solvent resistance may be improved. The PET used herein had a number average molecular weight of 42,492 and a weight average molecular weight of 58,243.

≪ Formula 4 >

≪ Example 1 >

PET beads were prepared in the same manner as in Comparative Example 2 except that PET chips copolymerized with 1 mol% of copolymerized IPA were used. The PET used herein had a number average molecular weight of 27,512 and a weight average molecular weight of 31,753.

≪ Example 2 >

PET beads were prepared in the same manner as in Comparative Example 2 except that the PET chips were used in which the content of copolymerized isophthalic acid (IPA) was increased to 5 mol%. The PET used herein had a number average molecular weight of 27,753 and a weight average molecular weight of 38,732.

≪ Example 3 >

PET beads were prepared in the same manner as in Comparative Example 2 except that the PET chips were used in which the content of copolymerized IPA was increased to 10 mol%. The PET used herein had a number average molecular weight of 24,320 and a weight average molecular weight of 35,651.

<Example 4>

PET beads were prepared in the same manner as in Comparative Example 3 except that the PET chips were used in which the content of copolymerized neopentyl glycol (NPG) was increased to 1 mol%. The PET used herein had a number average molecular weight of 42,780 and a weight average molecular weight of 58,432.

&Lt; Example 5 >

PET beads were prepared in the same manner as in Comparative Example 3 except that the amount of copolymerized NPG was increased to 5 mol% and PET chips were used. The PET used herein had a number average molecular weight of 40,752 and a weight average molecular weight of 53,524.

&Lt; Example 6 >

PET beads were prepared in the same manner as in Comparative Example 3 except that the amount of copolymerized NPG was increased to 10 mol% to prepare a PET chip. The PET used herein had a number average molecular weight of 42,421 and a weight average molecular weight of 57,249.

&Lt; Comparative Example 5 &

PET beads were prepared in the same manner as in Comparative Example 2 except that the amount of copolymerized IPA was increased to 15 mol% to prepare a PET chip. The PET used herein had a number average molecular weight of 27,531 and a weight average molecular weight of 36,423.

&Lt; Comparative Example 6 >

PET beads were prepared in the same manner as in Comparative Example 3 except that the amount of copolymerized NPG was increased to 15 mol% to prepare a PET chip. The PET used herein had a number average molecular weight of 44,324 and a weight average molecular weight of 58,433.

<Experimental Example> Measurement of physical properties of particles

In order to compare the PET beads ground in Examples 1 to 6 and Comparative Examples 1 to 6, the average particle size, product yield, compressive modulus, scratching and pressing degree of each sample were measured and the results are shown in Table 1 below Respectively.

At this time, the average particle size, product yield, compressive modulus, scratch and degree of pressing were evaluated in the following manner.

(One). Average particle size

Beckman coulter counter Multisizer 3, which measures the volume and particle size distribution of particles using an electrical resistance method.

In the above measurement, ISOTO was used as a base solution, the concentration at the time of particle administration was adjusted to 3 to 4%, and the Aperture Tube was used at 200.

(2). Product yield

After pulverization and classification, the mixture was pulverized to have an average particle diameter of 35 to 45 mu m, a C.V. The yield of particles less than 35% was measured.

(3). Evaluation of compressive modulus

The compressive modulus was evaluated by pulverized beads according to the type of PET.

At this time, MCT-500W (SHIMADZU Corp) equipment was used for evaluation of compressive modulus, and the measurement condition was Flat 50 type, and the test force was 100 mN.

In addition, the loading rate was 10 and the holding time was 5 seconds, and the average value after 5 measurements was confirmed.

(4). Scratch evaluation

The particles prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were coated on a PET film, and then the coated surface was bonded to another PET film, and mounted on a vibration tester to perform reciprocating vibration evaluation. At this time, the shaker C-SK-6 was used as the vibration tester, and the operation was carried out at 300 rpm for 1 hour.

As a criterion for judgment, when the degree of scratching of the light guide plate after vibration was confirmed by a microscope, and a plate with 2 cm size of "star", "bee" and "sun" If you can clearly read A, if you can easily distinguish between letters A and B, and if you can not distinguish between letters, you can not distinguish between letters C and D.

       (5). Pressed evaluation

After the particles prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were coated on a PET film, the coated surface was joined to the light guide plate, and a weight of 6 kg was placed thereon. Then, light was irradiated to the lower portion, .

At this time, as the criterion, the degree of white spot was visually confirmed and classified as good or bad.

[Table 1]

As shown in Table 1, when the pulverized beads were prepared using the PET homopolymer chip of Comparative Example 1, it was found that the average particle size and product yield were high, but the scratching phenomenon was severe.

However, Comparative Example 2 and Comparative Example 3 using PET copolymerized with IPA and EG showed generally good scratch characteristics, and Comparative Example 4 copolymerized with CHDM exhibited almost the same level of physical properties as Comparative Example 1.

These results are also related to compressive modulus. The higher the value of compressive modulus, the harder the particles, and thus the greater the scratching effect, indicating that the PET copolymerized with IPA and EG is superior in terms of scratch resistance.

However, in Comparative Example 4 copolymerized with CHDM, as in the case of the PET homopolymer, the average particle size was low and the yield was high, but the compressive modulus was high and the scratch resistance was degraded.

This seems to be due to the fact that the polymer chains are still hard, even if CHDM is used as a comonomer. That is, since the aromatic ring is replaced with a saturated cyclic alkylene and the free space is not increased to a meaningful level, the effect of improving the scratch characteristics as the crystallization speed is slowed is insignificant.

On the other hand, in Examples 1 to 6 in which IPA or NPG was copolymerized, it was found that as the copolymerization content was increased, the softening property decreased, and the scratch resistance was further improved.

This is because as the PET copolymerized with IPA is transformed from the linear structure of TPA to the jigged structure, the free space of the polymer chain inside the particle is increased. This is because the range in which the polymer can flow when the impact is applied is increased Of the total population.

In the case of NPG, as described above, it is considered that the addition of the methyl group provides the effect of increasing the free space by blocking the distance between the molecular chains with the side chain as in the case of IPA.

However, as shown in Comparative Example 5 and Comparative Example 6, when the content of IPA and NPG was increased to 15 mol% or more, it was found that the pressing property was worse, which is caused by excessive compression elastic modulus.

Accordingly, when the beads manufactured in Comparative Example 5 and Comparative Example 6 are used, the distance between the light guide plate and the reflective film can not be maintained due to the external impact, It is difficult to use

While the present invention has been described with reference to the preferred embodiments, it is to be understood that the invention is not limited to the exemplary embodiments, but is capable of various modifications and alterations within the scope of the invention.

Claims (9)

A polyethylene terephthalate (PET) represented by the following formula (2) wherein a part of terephthalic acid is substituted with isophthalic acid and copolymerized in polyethylene terephthalate (PET) represented by the following formula
An anti-blocking PET bead comprising polyethylene terephthalate (PET) represented by the following formula (3) wherein a part of ethylene glycol is substituted with neopentyl glycol in polyethylene terephthalate (PET)
[Chemical Formula 1]

(2)

(3)

(In the above formulas (1) to (3), m and n are independently an integer of 1 to 1000) The antiblocking PET bead according to claim 1, wherein the content of the copolymerized isophthalic acid or neopentyl glycol is 0.6 to 14 mol%. 3. The anti-blocking PET bead according to claim 2, wherein the content of the copolymerized isophthalic acid or neopentyl glycol is 1 to 10 mol%. In the production of PET beads by pulverizing a polyethylene terephthalate (PET) chip,
Wherein the PET chip is a PET of the following formula (2) wherein a part of the terephthalic acid is substituted with an isophthalic acid and copolymerized,
A process for producing a PET bead characterized in that PET is represented by the following formula (3) in which a part of ethylene glycol is substituted with neopentyl glycol in PET of the following formula (1)
[Chemical Formula 1]

(2)

(3)

(In the above formulas (1) to (3), m and n are independently an integer of 1 to 1000) 5. The method of producing PET beads according to claim 4, wherein the PET chips are pulverized in a frozen state to produce PET beads. The method for producing PET beads according to claim 5, wherein the PET chip is frozen by using liquid nitrogen as a refrigerant. 5. The method of manufacturing PET beads according to claim 4, further comprising a sphering process of sphering the outer circumferential surface of the PET bead produced. Base film, and
And an anti-blocking bead coated on either side of the substrate film,
The anti-blocking bead is the PET bead according to any one of claims 1 to 3. Light source,
A light guide plate that reflects incident light from the light source to the inside, and
The light source assembly according to claim 8, which is disposed on a surface facing the light guide plate.