KR20170058592A - Primer composition for reflective sheet and method for manufacturing retroreflective sheet using the same - Google Patents

Abstract

A disclosed primer composition for a reflective sheet comprises urethane polyol and a curable isocyanate compound obtained by conducting reaction of ester-based polyol obtained through a reaction of polybasic acid and polybasic alcohol with an additional isocyanate compound. The polybasic acid comprises at least one selected from the group consisting of adipic acid, isophthalic acid, and terephthalic acid and at least one selected from the group consisting of azelaic acid, sebacic acid, and dodecanediol acid. The polybasic alcohol includes bisphenol-based glycol and at least one selected from the group including ethylene glycol, 1,4-butandiol, neopentylglycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol. When the composition of the present invention is used, an adhesive layer having high adhesion with a metal film can be provided on a reflective sheet.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primer composition for a reflective sheet and a method for manufacturing the same, and a method of manufacturing a retroreflective sheet using the primer composition.

The present invention relates to a primer composition for a reflective sheet, and more particularly, to a primer composition for a reflective sheet and a method for producing a retroreflective sheet using the same.

A retroreflective sheet is a reflective sheet that reflects light in a direction parallel to incident light, as opposed to being reflected at an angle equal to the incident angle when light is incident. Such a retroreflective sheet returns light toward a light source, so that when the light source is exposed at night, it is very distinguishable and widely used for safety belts, traffic signs, clothing accessories, and the like.

The retroreflective sheet may include a glass bead coated for retroreflection, or may include a microprism. The light incident on the glass beads may be refracted from the back surface of the beads and then reflected toward the light source. The light incident on the microprism can be reflected toward the light source in the same direction as the direction in which the light is refracted in order from the inclined plane.

The retroreflective sheet including the micro-prism has a structure that further includes a reflective layer including a metal to increase the reflectance. However, there is a problem that the reflective layer is easily peeled or damaged by use.

An object of the present invention is to provide a primer composition for a reflective sheet which can increase the adhesiveness of a metal reflection layer.

It is another object of the present invention to provide a method for producing a retroreflective sheet using the primer composition.

The primer composition for a reflection sheet according to an embodiment of the present invention includes a urethane polyol and a cured isocyanate compound obtained by reacting an ester polyol obtained through a reaction of a polyhydric acid with a polyhydric alcohol with an additional isocyanate compound. The polyhydric acid includes at least one selected from the group consisting of adipic acid, isophthalic acid and terephthalic acid and at least one selected from azelaic acid, sebacic acid and dodecanediol acid. The polyhydric alcohol includes at least one selected from the group consisting of ethylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, and bisphenol- .

In one embodiment, the bisphenol-based glycol comprises bisphenol A bispropylene glycol ether.

In one embodiment, the additional isocyanate compound comprises at least one selected from 2,4-toluene diisocyanate, 4,4-methylene bis (phenyl isocyanate) and hexamethyl diisocyanate.

In one embodiment, the additional isocyanate is reacted with 1 to 4 parts by weight based on 100 parts by weight of the ester-based polyol.

In one embodiment, the number average molecular weight of the urethane polyol is from 5,000 to 15,000 and the weight average molecular weight is from 20,000 to 35,000.

In one embodiment, the cured isocyanate compound comprises at least one selected from trimethylolpropane-added toluene diisocyanate and hexamethylene diisocyanate trimersisocyanurate.

In one embodiment, the cured isocyanate compound is mixed in an amount of 1 to 4 parts by weight based on 100 parts by weight of the urethane polyol.

In one embodiment, the urethane primer composition further comprises a silane coupling agent.

According to the present invention, it is possible to provide an adhesive layer having high adhesion to a metal film. Further, the urethane primer composition for forming the adhesive layer is formed from an ester-based polyol containing a urethane main chain, whereby the stretchability of the adhesive layer is improved and the peel resistance and the like can be improved.

1 and 2 are sectional views showing a method of manufacturing a retroreflective sheet according to an embodiment of the present invention.
3 to 6 are sectional views showing a retroreflective sheet manufactured according to an embodiment of the present invention.

Hereinafter, a urethane primer composition for a reflective sheet and a method for manufacturing a retroreflective sheet according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

It is to be understood that the invention is not to be limited to the specific embodiments thereof, and that all changes, equivalents, and equivalents falling within the spirit and scope of the invention, It should be understood that it includes water and alternatives.

In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

1 and 2 are sectional views showing a method of manufacturing a retroreflective sheet according to an embodiment of the present invention.

Referring to FIG. 1, a urethane primer composition containing a urethane polyol and a cured isocyanate compound containing a urethane bond in a main chain is coated on a base substrate 100 to form an adhesive layer 110.

The base substrate 100 may include a polymer film including a resin, a polymer sheet or release paper, and the like. For example, the base substrate 100 may be formed of a material selected from the group consisting of polyethylene terephthalate, nylon, polymethylmethacrylate, polycarbonate, polyimide, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, triacetylcellulose, . ≪ / RTI >

Further, in terms of the shape, the base substrate 100 may have an uneven upper surface. For example, the adhesive layer 110 may be applied directly onto a microprism having a cube corner.

The urethane primer composition may be of a two-part type. That is, the urethane primer composition may be obtained by mixing a curing agent containing the curing isocyanate compound and a subject containing the urethane polyol.

The urethane polyol is an ester-type polyol obtained by condensation polymerization of an ester compound obtained through a reaction between a polyhydric acid and a polyhydric alcohol. In addition, the ester-based polyol includes a urethane bond in the main chain by reacting with the diisocyanate for increasing the molecular weight.

For example, the polyvalent acid includes at least two acid groups (-COOH). Specifically, the polyvalent acid includes at least one selected from the group consisting of adipic acid, isophthalic acid, and terephthalic acid. For example, the polyvalent acid may be a mixture comprising both adipic acid, isophthalic acid and terephthalic acid.

More preferably, the polybasic acid mixture may further include a polyvalent acid containing a straight chain alkylene group having 7 to 10 carbon atoms. For example, the polybasic acid mixture may include at least one selected from the group consisting of azelaic acid, sebacic acid and dodecanedioic acid, more preferably dodecanedioic acid . The polyvalent acid containing a straight chain alkylene group having 7 to 10 carbon atoms imparts flexibility to the resin, thereby improving the durability and adhesion of the adhesive layer to an external force.

The polyhydric alcohol contains at least two or more hydroxyl groups (-OH). Specifically, the polyhydric alcohol includes at least one selected from the group consisting of ethylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol and 1,6-hexanediol. For example, the polyhydric alcohol may be a mixture comprising both ethylene glycol, 1,4-butanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol.

More preferably, the polyhydric alcohol mixture may further comprise a bisphenol glycol compound. For example, the bisphenol glycol compound may include bisphenol A bis propylene glycol ether. The bisphenol-based glycol compound can improve the adhesive strength of the adhesive layer.

The polybasic acid mixture and the polyhydric alcohol can be reacted at, for example, 200 ° C to 260 ° C to form an ester-based polyol. Specifically, the polybasic acid mixture and the polyhydric alcohol may be reacted with each other at 220 ° C to 230 ° C to be esterified, and then the ester polyol may be formed through condensation polymerization at 240 ° C to 260 ° C. For example, the ester-based polyol may be represented by the following formula (1).

≪ Formula 1 >

(Wherein, in the formula (1), the above and below are a single connected formula).

The ester-based polyol may be reacted with an additional isocyanate compound so as to have an appropriate molecular weight. For example, the additional isocyanate compound may include at least one selected from 2,4-toluene diisocyanate, 4,4-methylene bis (phenyl isocyanate) and hexamethyl diisocyanate. The amount of the additional isocyanate compound added for the reaction may be 0.1 to 5 parts by weight, more preferably 1 to 4 parts by weight, based on 100 parts by weight of the ester-based polyol.

Through the reaction, a urethane polyol containing a urethane group in the main chain can be obtained. For example, the number average molecular weight of the polyol may be from 5,000 to 15,000 and the weight average molecular weight may be from 20,000 to 35,000. If the molecular weight of the polyol is smaller than the above range, the coating property may be deteriorated. If the molecular weight is larger than the above range, the adhesive strength of the adhesive layer 110 may be lowered.

The urethane primer composition further includes a silane coupling agent to improve adhesion with the metal layer to be formed later. Examples of the silane coupling agent include trialkoxysilane having an amino group such as 3-aminopropyltriethoxysilane and N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, trialkoxysilane having 3-glycidoxypropyltrimethoxysilane Trialkoxysilane having a glycidyl group such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane can be used. These may be used singly or in combination. The silane coupling agent may be provided in the above-mentioned subject, for example, the content may be 1,000 ppm to 8,000 ppm.

The cured isocyanate compound reacts with the subject polyol to form a cured urethane primer composition. For example, the cured isocyanate compound may include trimethylolpropane-added toluene diisocyanate, hexamethylene diisocyanate trimethyl isocyanurate, and specifically, Coronate L, Coronate HX (available from Tosho) Desmodur L75, Desmodur N3300 (manufactured by Bayer), AK-75 and DN-980S (available from Aekyung Chemical Co., Ltd.).

Preferably, the content of the cured isocyanate compound relative to 100 parts by weight of the urethane polyol having a urethane bond in the main chain may be 3 to 5 parts by weight.

The urethane primer composition may further comprise an appropriate solvent. The solvent may be included in the subject or the curing agent. For example, the solvent may include cyclohexanone, toluene, xylene, ethyl acetate, methyl ethyl ketone, etc., which may be used singly or in combination.

The solvent may be provided such that the polyurethane resin has an appropriate viscosity. For example, the solids content of the urethane primer composition including the solvent may be from 30% by weight to 40% by weight, and the viscosity may be from about 200 to 350 mPa.s.

The urethane primer composition may be provided by a gravure coater, a microgravure coater, a die coater, a spray, or the like. For example, the urethane primer composition may be provided so that the thickness of the adhesive layer 110 is 1 탆 or less.

Referring to FIG. 2, a metal film 120 is provided on the adhesive layer 110. The metal film 120 may include aluminum, copper, silver, gold, nickel, and the like. The metal film 120 may be formed on the adhesive layer 110 through deposition or sputtering. Preferably, the metal film 120 is formed directly on the adhesive layer 110.

For example, the metal film 120 may be formed through plasma ion implantation. The ion implantation process may be performed using a gas comprising argon, nitrogen, oxygen, helium, or a combination thereof. For example, the ion implantation energy may be 10 kV to 70 kV, the ion implantation time may be 5 seconds to 30 seconds, and the ion implantation dose may be 2 × ^{10 15} / cm 2 to 4 × 10 ¹⁷ / cm 2.

According to the present invention, it is possible to provide an adhesive layer having high adhesion to a metal film. Further, the urethane primer composition for forming the adhesive layer is formed from an ester-based polyol containing a urethane main chain, whereby the stretchability of the adhesive layer is improved and the peel resistance and the like can be improved.

3 to 6 are sectional views showing a retroreflective sheet according to an embodiment of the present invention.

Referring to FIG. 3, the retroreflective sheet includes a micro prism array 10, a front protective layer 20, an adhesive layer 30, and a metal film 40.

The front surface protection layer 20 is coupled to one surface of the micro prism array 10. The front surface protection layer 20 may include an acrylic resin having a high transparency, polymethyl methacrylate resin, or the like.

The micro prism array 10 is disposed so as to protrude in a direction opposite to the front protective layer 20. The micro prism array 10 may include a corner cube for reflecting light incident from the front protective layer 20 in a direction opposite to the incident direction, that is, toward the light source. For example, the height of the corner cube may be about 20 [mu] m to 500 [mu] m. Since the shape of the corner cube for retroreflection is known, a detailed description thereof may be omitted. For example, the corner cubes may have a triangular pyramid shape and may have different sizes. In addition, the shape of the corner cube is not limited to the triangular prism, but may have a shape such as a square pyramid or hemisphere.

For example, the corner cube can be manufactured by a method such as a flying cutting, a grinding, a thermal transfer method, a cast rolling method, or the like.

For example, the corner cube may include polycarbonate, polymethyl methacrylate, polyethylene terephthalate, and the like.

The adhesive layer 30 may be formed from a urethane primer composition comprising a urethane polyol containing a urethane bond in the main chain and a cured isocyanate compound. For example, on the lower surface of the microprism array 10, that is, on the projecting surface. For example, the urethane primer composition may be applied to the projecting surface of the microprism array 10 and cured by heating or the like.

The polyol is an ester-based polyol obtained by condensation polymerization of an ester compound obtained through the reaction of a polyhydric acid with a polyhydric alcohol. In addition, the ester-based polyol includes a urethane bond in the main chain by reacting with the diisocyanate for increasing the molecular weight.

The urethane primer composition may be the same as that used in the method of manufacturing the reflective sheet according to the embodiment of the present invention described above, and thus a detailed description thereof will be omitted.

A metal film (40) is disposed on the lower surface of the adhesive layer (30). The metal film 40 may be formed directly on the lower surface of the adhesive layer 30 through deposition, plasma ion implantation, sputtering, or the like. For example, the metal film 40 may include aluminum, copper, silver, gold, nickel, and the like.

4, the retroreflective sheet includes a micro prism array 10, a front protective layer 20, an adhesive layer 30, a metal film 40, and a spacing member 50.

The gap holding member 50 is partially disposed between the micro-prism array 10 and the adhesive layer 30 to form an air layer 55 between the micro-prism array 10 and the adhesive layer 30 .

The air layer 55 may increase the refractive index difference in the retroreflective sheet to increase the reflection efficiency.

5, the retroreflective sheet includes a micro prism array 10, a front protective layer 20, an adhesive layer 30, a metal film 40, and an intermediate layer 50.

The intermediate layer 50 is disposed between the micro-prism array 10 and the adhesive layer 30. The intermediate layer 50 may contact the corner cube of the microprism array 10 as shown, or may be spaced apart by a spacing member, as shown in Fig. For example, the intermediate layer 50 may include polyethylene terephthalate or the like.

The adhesive layer 30 may be bonded to the lower surface of the intermediate layer 50 to be spaced apart from the microfilm array 10. When the urethane primer composition for forming the adhesive layer 30 is applied directly to the microprism array 10, the corner cubes of the microfilm array 10 may be damaged by the solvent of the urethane primer composition.

In this embodiment, the microfilm array 10 can be prevented from being damaged by forming the adhesive layer 30 on the intermediate layer 50.

Referring to FIG. 6, the retroreflective sheet may include a micro prism array 10, a front protective layer 20, an adhesive layer 30, a metal film 40, and a rear protective layer 70.

The rear protective layer 70 protects the metal film 40. For example, the backside protective layer 70 may comprise polypropylene.

In order to adhere the rear protective layer 70 to the metal film 40, a rear adhesive layer may be additionally provided therebetween, and the same urethane primer composition as the contact layer 30 may be used.

Hereinafter, the structure and effects of the present invention will be described in detail through synthesis examples, examples and experimental results of the present invention.

Synthetic example

According to the following Table 1, a polybasic acid and a polyhydric alcohol were reacted to obtain an ester-based polyol. In Synthesis Example 1, titanium isopropoxide was used as a reaction catalyst, tin octoate was used as an esterification catalyst in Synthesis Examples 2 to 4, antimony trioxide (Synthesis Example 2, Synthesis Example 3) was used as a polycondensation catalyst, And tetrabutyl titanate (Synthesis Example 4) were used. The esterification reaction temperature was about 225 캜, and the polycondensation temperature was about 250 캜.

Table 2 shows the solid content and viscosity of the ester-based polyol obtained according to Table 1.

Table 1

Table 2

The ester-based polyol of Synthesis Example 1 was reacted with 2,4-toluene diisocyanate to obtain a polyol having a urethane bond in the main chain. A urethane primer composition was prepared by mixing 100 parts by weight of the polyol and trialkoxysilane (5,000 ppm) having a glycidyl group as a coupling agent, and 4 parts by weight of Coronate HX as a cured isocyanate compound. The urethane primer composition was coated on a polycarbonate sheet and cured to form an adhesive layer having a thickness of about 1 탆, and then an aluminum film having a thickness of about 100 nm was formed by sputtering. Linking polyol was synthesized by different reaction ratios of the ester polyol and 2,4-toluene diisocyanate (addition isocyanate), and the storage stability (observation of transparency change and observation of the formation of precipitate after visual observation after one month storage) (JIS K 5600-5-6) was evaluated and shown in Table 3 below. The content of the additional isocyanate was about 100 parts by weight of the ester-based polyol, and the adhesive strength was expressed by the number of the remaining pieces after peeling off the test tape having the piece of 10 X 10.

Table 3

The ester-based polyol of Synthesis Example 2 was reacted with 2,4-toluene diisocyanate to obtain a polyol having a urethane bond in the main chain. A urethane primer composition was prepared by mixing 100 parts by weight of the polyol and trialkoxysilane (5,000 ppm) having a glycidyl group as a coupling agent, and 4 parts by weight of Coronate HX as a cured isocyanate compound. The urethane primer composition was coated on a polycarbonate sheet and cured to form an adhesive layer having a thickness of about 1 탆, and then an aluminum film having a thickness of about 100 nm was formed by sputtering. Linking polyol was synthesized by different reaction ratios of the ester polyol and 2,4-toluene diisocyanate (addition isocyanate), and the storage stability (observation of transparency change and observation of the formation of precipitate after visual observation after one month storage) (JIS K 5600-5-6) were evaluated and are shown in Table 4 below. The content of the additional isocyanate was about 100 parts by weight of the ester-based polyol, and the adhesive strength was expressed by the number of the remaining pieces after peeling off the test tape having the piece of 10 X 10.

Table 4

The ester-based polyol of Synthesis Example 3 was reacted with 2,4-toluene diisocyanate to obtain a polyol having a urethane bond in the main chain. A urethane primer composition was prepared by mixing 100 parts by weight of the polyol and trialkoxysilane (5,000 ppm) having a glycidyl group as a coupling agent, and 4 parts by weight of Coronate HX as a cured isocyanate compound. The urethane primer composition was coated on a polycarbonate sheet and cured to form an adhesive layer having a thickness of about 1 탆, and then an aluminum film having a thickness of about 100 nm was formed by sputtering. Linking polyol was synthesized by different reaction ratios of the ester polyol and 2,4-toluene diisocyanate (addition isocyanate), and the storage stability (observation of transparency change and observation of the formation of precipitate after visual observation after one month storage) (JIS K 5600-5-6) were evaluated and are shown in Table 5 below. The content of the additional isocyanate was about 100 parts by weight of the ester-based polyol, and the adhesive strength was expressed by the number of the remaining pieces after peeling off the test tape having the piece of 10 X 10.

Table 5

The ester-based polyol of Synthesis Example 4 was reacted with 2,4-toluene diisocyanate to obtain a polyol having a urethane bond in the main chain. A urethane primer composition was prepared by mixing 100 parts by weight of the polyol and trialkoxysilane (5,000 ppm) having a glycidyl group as a coupling agent, and 4 parts by weight of Coronate HX as a cured isocyanate compound. The urethane primer composition was coated on a polycarbonate sheet and cured to form an adhesive layer having a thickness of about 1 탆, and then an aluminum film having a thickness of about 100 nm was formed by sputtering. Linking polyol was synthesized by different reaction ratios of the ester polyol and 2,4-toluene diisocyanate (addition isocyanate), and the storage stability (observation of transparency change and observation of the formation of precipitate after visual observation after one month storage) (JIS K 5600-5-6) were evaluated and shown in Table 6 below. The content of the additional isocyanate was about 100 parts by weight of the ester-based polyol, and the adhesive strength was expressed by the number of the remaining pieces after peeling off the test tape having the piece of 10 X 10.

Table 6

Referring to Tables 3 to 6, it can be confirmed that when the content of the additional isocyanate is increased, the storage stability is lowered. This may be due to the fact that the unreacted isocyanate group reacts with moisture or the like in the air.

Further, in order to obtain excellent adhesion, the content of the additional isocyanate compound needs to be used within a specific range, and it is preferable to include dodecanethiol acid and bisphenolic glycol in the synthesis of the ester-based polyol.

INDUSTRIAL APPLICABILITY The present invention can be applied to various industries that require a reflective sheet such as a reflective band.

Claims (9)

A urethane polyol obtained by reacting an ester-type polyol obtained through the reaction of a polyvalent acid with a polyvalent alcohol with an additional isocyanate compound; And
A cured isocyanate compound,
Wherein the polyvalent acid comprises at least one selected from the group consisting of adipic acid, isophthalic acid and terephthalic acid and at least one selected from azelaic acid, sebacic acid and dodecanediol acid,
Wherein the polyhydric alcohol comprises at least one selected from the group consisting of ethylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, and bisphenol- Wherein the primer composition is a primer composition. The primer composition for a reflective sheet according to claim 1, wherein the bisphenol-based glycol comprises bisphenol A bispropylene glycol ether. The reflective sheet of claim 1, wherein the additional isocyanate compound comprises at least one selected from 2,4-toluene diisocyanate, 4,4-methylene bis (phenyl isocyanate) and hexamethyl diisocyanate. Composition. 2. The primer composition for a reflective sheet according to claim 1, wherein the additional isocyanate compound is reacted at 1 to 4 parts by weight with respect to 100 parts by weight of the ester-based polyol. The primer composition for a reflective sheet according to claim 1, wherein the urethane polyol has a number average molecular weight of 5,000 to 15,000 and a weight average molecular weight of 20,000 to 35,000. The primer composition for a reflective sheet according to claim 1, wherein the cured isocyanate compound comprises at least one selected from trimethylolpropane-added toluene diisocyanate and hexamethylene diisocyanate trimethyl isocyanurate. 7. The primer composition for a reflective sheet according to claim 6, wherein the cured isocyanate compound is mixed in an amount of 1 to 4 parts by weight based on 100 parts by weight of the urethane polyol. The primer composition for a reflective sheet according to claim 1, further comprising a silane coupling agent. Applying the primer composition of any one of claims 1 to 8 on a base substrate to form an adhesive layer; And
And depositing a metal film on the adhesive layer.

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