KR20140132667A - Method for ethylenevinylacetate with low melt index - Google Patents

Abstract

The present invention relates to a method for manufacturing ethylene vinyl acetate (EVA) whose melt index is not more than 10 g per 10 minutes, comprising a step of radiating 1-25 kg of electron beam to ethylene vinyl acetate resin compositions including ethylene vinyl acetate resin whose content of vinyl acetate is 15-50 wt%. According to the manufacturing method of the present invention, the manufactured ethylene vinyl acetate has a high content vinyl acetate, and the physical properties such as transparency and elasticity thereof are excellent leading to the ease of process. In addition, the manufactured ethylene vinyl acetate can be used in various industries due to excellent mechanical physical properties like low melt index.

Description

METHOD FOR ETHYLENEVINYLACETATE WITH LOW MELT INDEX < RTI ID = 0.0 >

The present invention relates to a process for producing ethylene vinyl acetate having a low melt index and, more particularly, to a process for producing ethylene vinyl acetate having a low melt index, which is excellent in physical properties such as transparency and elasticity, including a high content of vinyl acetate, The present invention relates to a process for producing ethylene vinyl acetate having a low melt index capable of improving productivity and economy by preparing ethylene vinyl acetate which can be applied to various industrial applications by a method including a simple reforming step.

Ethylene vinyl acetate is a thermoplastic resin that is used in a variety of industrial applications such as shoes, adhesives, coatings, wires, flame retardant compounds, and solar cells. Particularly, ethylene vinyl acetate having a vinyl acetate content of 18% or more has excellent dispersibility of elasticity and inorganic additives and is very transparent. Therefore, the use amount of ethylene vinyl acetate is greatly increased in the fields of shoe foam, electric wires, fire retardant compounds and solar cell encapsulants.

In particular, the shoe foam sector requires high elasticity, low specific gravity and flexibility. In order to maintain high price elasticity, low specific gravity and flexibility while maintaining price competitiveness, it is necessary to use ethylene vinyl acetate. As the vinyl acetate content increases, , The content of vinyl acetate in ethylene vinyl acetate is increased.

In order to improve the flame retardancy of the flame retardant compound, the content of the flame retardant should be increased. In order to secure the excellent flame retardancy of the ethylene vinyl acetate, at least 40% of the inorganic flame retardant such as magnesium hydroxide, aluminum hydroxide and antimony trioxide should be contained. The higher the content of vinyl acetate in ethylene vinyl acetate is, the more compatibility with the inorganic material increases, so it is advantageous to increase the vinyl acetate content in order to increase the amount of the inorganic flame retardant.

The ethylene vinyl acetate sheet used as the encapsulant in the solar module has higher transparency of the sheet as the vinyl acetate content is higher, and the efficiency of the module is increased. Therefore, the ethylene vinyl acetate sheet usually contains 26% or more of vinyl acetate.

On the other hand, ethylene vinyl acetate can be prepared by injecting ethylene and vinyl acetate into an autoclave reactor or a tubular reactor at an appropriate ratio and polymerizing at a high temperature / high pressure. At this time, if the content of vinyl acetate introduced into the reactor is increased, some vinyl acetate may act as a telomer, and the molecular weight of ethylene vinyl acetate may be lowered. As the molecular weight of ethylene vinyl acetate decreases, the melt index increases and the melt strength decreases. For example, in the case of producing ethylene vinyl acetate having a content of 33% vinyl acetate, the melt index which can be maximally lowered is about 10, and the melt strength is about 30 mN.

As described above, when the melt index increases simultaneously with the increase of the vinyl acetate content, there is a limit in lowering the mechanical properties and lowering the workability. Therefore, when ethylene vinyl acetate having a high content of vinyl acetate is used, flexibility and elasticity are excellent, but mechanical properties and processability are degraded. Thus, ethylene vinyl vinyl acetate is used in shoe foam, electric wire, There was a restriction to use it.

In order to overcome the limitation of ethylene vinyl acetate, a method of post-reaction of ethylene vinyl acetate produced in the reactor to increase the mechanical properties and processability has been used. A modification method using peroxide, which is a method mainly used in the post-treatment, is an extrusion reaction method in which ethylene vinyl acetate resin and peroxide are fed into an extruder, the melt index is lowered in the extruder, and the melt strength is increased. The peroxide modification method can reform ethylene vinyl acetate in various combinations and methods, but the amount of work loss is very large, and various problems such as contamination, repackaging, and processing defect are caused.

The work loss and repacking caused by the peroxide modification process become the main factor of the cost increase and become the limitation of commercialization. The pollutants which are introduced during the reforming process or generated during the reforming process are the quality of the ethylene vinyl acetate finished product It can cause problems.

As a result, it has been found that ethylene vinyl acetate which is excellent in transparency and elasticity including a high content of vinyl acetate, has a high melt strength and excellent mechanical properties through a simple after-treatment process and can be applied to various industrial applications such as shoe foam, There is still a need to develop a method that can be manufactured simply and economically.

The present invention relates to a process for producing ethylene vinyl acetate which is excellent in physical properties such as transparency and elasticity and which is easy to process but which has excellent mechanical properties and can be applied to various industrial applications by a simple reforming step And a process for producing ethylene vinyl acetate having a low melt index capable of improving productivity and economical efficiency.

The present invention relates to a method for producing an ethylene vinyl acetate resin composition, which comprises irradiating an ethylene vinyl acetate resin composition containing an ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% with electron beams of 1 to 25 kGy, ≪ / RTI > with ethylene vinyl acetate (EVA).

Hereinafter, a method for producing ethylene vinyl acetate (EVA) having a low melt index according to a specific embodiment of the present invention will be described in detail.

According to an embodiment of the present invention, there is provided a method for producing an ethylene vinyl acetate resin composition, comprising: irradiating an ethylene vinyl acetate resin composition containing an ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% with electron beams of 1 to 25 kGy; Of ethylene vinyl acetate (EVA) having a melt index of < RTI ID = 0.0 >

The present inventors have recognized that ethylene vinyl acetate having a high content of vinyl acetate has a low melt strength and a high melt index and thus has a limit of deteriorating mechanical properties and processability. It has been found out that, while having high transparency, flexibility and elasticity, Studies were conducted to produce ethylene vinyl acetate with excellent processability. Ethylene vinyl acetate having a low melt index of 10 g / 10 min or less can be prepared by irradiating an ethylene vinyl acetate composition containing a high content of vinyl acetate with a certain irradiation dose of electron beam Through experiments, we confirmed and completed the invention.

In particular, the process for producing ethylene vinyl acetate described above is less economical than conventional peroxide reforming methods due to less contamination or defective processing in the manufacturing process, and less work loss. In addition, the manufacturing method of this embodiment can omit the step of unpacking and repackaging the packaging, thereby efficiently producing ethylene vinyl acetate containing a high content of vinyl acetate in a simple and economical manner and having a low melt index .

In addition, the above-described production method can be applied to a method for producing ethylene vinyl acetate by a simple modification method of irradiating an ethylene vinyl acetate composition with an electron beam of a certain irradiation dose, and also by a method such as melt strength, melt index, shear thinning index, Ethylene vinyl acetate having excellent physical properties can be produced by improving mechanical properties.

Therefore, the ethylene vinyl acetate provided by the manufacturing method of one embodiment exhibits a low melt index with a high content of vinyl acetate and can be used for film molding, extrusion molding, foam molding, etc., and has a high shear thinning index, And the extrusion load, power consumption, pressure and the like can be lowered under a high shear force, so that the mechanical properties and workability are excellent.

Meanwhile, in the manufacturing method of the embodiment, before the step of irradiating the electron beam, the step of spreading the ethylene vinyl acetate resin composition to the auxiliary frame to a thickness of 1 to 16 cm; Or packaging the ethylene vinyl acetate resin composition into a packaging bag.

That is, the ethylene vinyl acetate resin composition is spread to 1 to 16 cm thick on the auxiliary frame and irradiated with electron beams of 1 to 25 kGy, or the ethylene vinyl acetate resin composition is packed in a packaging bag, and electron beams of 1 to 25 kGy You can investigate. The thickness means the height from the bottom surface of the ethylene vinyl acetate resin composition spread on the bottom surface of the auxiliary frame.

The auxiliary frame may be any frame commonly known in the art and may include, for example, metal, paper, polymer film, wood, plastic, and the like.

As the packaging bag, materials known to be commonly used in the art may be used without limitation, and examples thereof include a polyolefin film, a Yarn woven fabric, a paper, a coated paper, a paper including a liner film, Etc. may be used.

In addition, the polyolefin film may be specifically formed of a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), an ultra low density polyethylene (VLDPE), a high density polyethylene (HDPE), a polypropylene (PP), an ethylene elastomer, Propylene-based elastomer, propylene-based plastomer, or a mixture thereof.

On the other hand, the step of irradiating the packaging bag with the electron beam can be carried out by placing the packaging bag in a metal roll or a metal frame-type conveyor and passing through the electron beam irradiation section. Therefore, if the irradiation of the electron beam is continued, the temperature of the metal roll or the mold may rise, and the packaging bag may melt so that the contents may flow out into the packaging bag or the packaging bag may not move smoothly on the conveyor. In order to prevent this, it is preferable to use a material made of a material which is stable even at a high temperature as a main material.

The total weight of the packaging bag is not limited, but may be 1000 kg or less for convenience of transportation. The packaging bag may be transported by using a manpower or a machine. In this case, the total weight of the packaging bag may be limited depending on the transportation mode, and the total weight of the packaging bag includes both the weight of the ethylene vinyl acetate resin composition and the packing bag . When the packaging bag is transported using a machine, about 1000 kg or less of the ethylene vinyl acetate resin composition can be packed using flecon packing or cargon packing, and preferably about 500 to 600 kg or less of ethylene The vinyl acetate resin composition can be packaged. And, when transported by hand, the total weight of the packaging bag can be about 50 kg or less, preferably about 5 to 50 kg, more preferably about 10 to 40 kg.

The size and shape of the auxiliary frame and the packing bag are not limited, but it is preferable that the auxiliary vinyl and the packing bag are constantly 1 cm or more in height and the ethylene vinyl acetate resin composition can be spread or packed to a constant thickness.

The method for producing ethylene vinyl acetate according to one embodiment of the present invention is a method for producing an ethylene vinyl acetate resin by spreading an ethylene vinyl acetate resin composition on a support frame or by packing it in a packaging bag and irradiating it with an electron beam through an electron beam processor to improve the physical properties of ethylene vinyl acetate Ethylene vinyl acetate can be produced economically and easily without addition of a special step or a reforming substance such as a peroxide.

In particular, the process for producing ethylene vinyl acetate has significantly less work loss than that using conventional peroxides, and the working speed can also be improved to over 700 kg per hour.

The ethylene vinyl acetate resin composition may be injected into an electron beam irradiating apparatus and irradiated with an electron beam. In particular, when the ethylene vinyl acetate resin composition is packaged in a packaging bag and irradiated with electron beams, the packaging bag may be formed in a raised or laid-down form depending on the shape and position of the irradiation apparatus. Preferably, So that the bag can pass through.

The electron beam may be irradiated on the ethylene vinyl acetate resin composition in one or both sides. If the thickness of the resin composition is thin, the cross-section irradiation is preferable. If the thickness of the resin composition is small, double-side irradiation is preferable, and the electron beam irradiation can be performed once or repeatedly on both sides or cross section.

The ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% may have a Rheotens melt strength of 1 mN to 30 mN. The ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% may have a melt index (190 ° C, 2.16 kg) of 15 g / 10 min or more, preferably a melt index of 190 g / 10 min Lt; 0 > C, 2.16 kg). Although the ethylene vinyl acetate resin has a low melt strength and a too high melt index, there is a limit in processability and moldability. However, as described above, the ethylene vinyl acetate resin is irradiated with an electron beam in a certain irradiation dose and is modified with ethylene vinyl acetate can do.

On the other hand, the ethylene vinyl acetate produced may have a melt index (190 DEG C, 2.16 kg) of 10 g / 10 min or less and preferably has a melt index (190 DEG C, 2.16 kg) of 0.01 to 5 g / . In particular, when the EVA has a melt index of 0.01 or less, the strength in the molten state is so high that the extruded load and the extruded torque are greatly increased and the stretching is not properly performed, which can make foaming, film molding, sheet molding, compounding and the like very difficult .

The melt index is related to the molecular weight, and it is a phenomenon that vinyl acetate acts as a reaction terminal (telomer) to lower the molecular weight of ethylene vinyl acetate containing a large amount of vinyl acetate and to increase the melt index, May appear. However, the ethylene vinyl acetate produced by the production method of one embodiment may contain a low melt index of 10 g / 10 min or less even though it contains a high content of vinyl acetate of 15 to 50 wt%, so that the mechanical properties and the processability Can be overcome.

The ethylene vinyl acetate produced may have a Rheotens 占 melt strength (170 占 폚) of 30 mN or more, and preferably 30 to 150 mN. Ethylene vinyl acetate having a melt strength of less than 30 mN is weak in elasticity and strength in a molten state, so that it is impossible to produce a sufficient sponge due to failure to form and grow bubbles during foaming molding. In the injection / extrusion process, It is difficult to form the desired shape.

In addition, the ethylene vinyl acetate produced may have an ARES (150 DEG C, 15% strain) shear thinning index of 4 to 25. The Shear Mint Index is the ratio of the viscosity at 1 rad / sec to the viscosity at 100 rad / sec. The higher the Shear Mint Index, the higher the viscosity at lower shear forces and the lower the viscosity at higher shear forces. Ethylene vinyl acetate having an ARES shear thinning index within the above range exhibits a high viscosity at low shear force and can maintain its shape without deformation and exhibits low viscosity at high shear force, thereby reducing extrusion load and power consumption.

The ethylene vinyl acetate to be produced may have a molecular weight distribution of 10 or more, and preferably 10 to 50. The molecular weight distribution in the above range is significantly higher than that of ethylene vinyl acetate resin having a content of vinyl acetate of 15 to 50 wt% before electron beam irradiation, and has a wide range of molecular weight distributions that can secure adequate mechanical strength and processability by electron beam modification Ethylene vinyl acetate can be produced.

The ethylene vinyl acetate resin composition may further comprise a photoreactive monomer, an antioxidant, a slip agent, an antiblocking agent, a UV stabilizer, a reaction aid, or a mixture thereof as an additive.

The antioxidant may increase the thermal stability and the oxidation stability of ethylene vinyl acetate to be produced. Specifically, the antioxidant may be a phenol-based antioxidant, a biphenol-based antioxidant, or a mixture thereof. In order to lower the complex viscosity and shear-thinning index of the ethylene vinyl acetate resin and to minimize discoloration, It is preferable to use an inhibitor.

As the phenolic antioxidant, antioxidants known to be commonly used in the art may be used without limitation, for example, octadecyl-3- (3,5-di-tert.butyl-4-hydroxyphenyl) -propionate Butylated hydroxytoluene, Pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 2 ', 3-bis [3- [3,5- hydroxyphenyl] propionyl]] propionohydrazide, or a mixture thereof.

As the non-phenolic antioxidant, antioxidants known to be commonly used in the art may be used without limitation, for example, Tris (2,4-ditert-butylphenyl) phosphite, 4,4'-Thiobis (6-tert-butyl-m-cresol), Bis- (2,4-di-t-butylphenol) Pentaerythritol Diphosphite, 2- (tert- , 8,10-tetrakis (tert-butyl) dibenzo [d, f] [1,3,2] dioxaphosphepin-6-yl) oxy) propyl) -methylphenyl) -ethyl-phosphite, Tris (Nonylphenyl) Phosphite, or a mixture thereof.

The antioxidant may be contained in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the ethylene vinyl acetate resin composition. When the antioxidant is contained in an excessively small amount, the oxidation stability of the produced ethylene vinyl acetate may be weakened, and if the antioxidant is contained too much, the electron beam reforming efficiency may be greatly reduced and discoloration of the ethylene vinyl acetate may be caused.

The ethylene vinyl acetate resin composition may further include an ultraviolet stabilizer that does not lower the efficiency of electron beam modification while maintaining thermal stability and oxidation stability of ethylene vinyl acetate to be produced. As such ultraviolet stabilizer, a hindered amine-based ultraviolet stabilizer may be preferably used, and a hindered amine ultraviolet stabilizer commonly known in the art may be used without limitation. Particularly, the hindered amine-based ultraviolet stabilizer can maintain the electron beam modifying effect of ethylene vinyl acetate to a satisfactory level, and can keep the required amount of electron beam to satisfy the target physical property low, thereby making ethylene vinyl acetate economically .

Specific examples of the ultraviolet stabilizer include Polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol, Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, Bis 1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, Poly [6 - [(1,1,3,3-tetramethylbutyl) amino] -1,3,5-triazine- [(2,2,6,6-tetramethyl-4-piperidinyl) imino] hexamethylene [2,2,6,6-tetramethyl-4-piperidinyl) imino]] or a mixture thereof, And 0.01 to 0.5 parts by weight of an ultraviolet stabilizer based on 100 parts by weight of the vinyl acetate resin composition.

Examples of the anti-blocking agent include, but are not limited to, olefins such as oleamide, stearamide, erucamide, ethylene bis-stearamide, and ethylene Bis-oleamide, or a mixture thereof. The antiblocking agent may be included in an amount of 0.02 to 0.5 part by weight based on 100 parts by weight of the ethylene vinyl acetate resin composition. If the content of the anti-blocking agent is too high, it may cause a color change in the electron beam modification process. When the content of the anti-blocking agent is too low, a problem of sticking to the pellets occurs. Therefore, desirable.

The photoreactive monomer serves as an electron beam modifying auxiliary for efficiently modifying an electron beam. The photoreactive monomer may be an acrylic acid, an acrylate, a methacrylate, a methacrylate, a dicarboxylic acid having a double bond, A dicarboxylic acid ester having a bond, a dicarboxylic acid anhydride having a double bond, a silane coupling agent, or a mixture thereof.

In one embodiment of the photoreactive monomer, the dicarboxylic acid is selected from the group consisting of maleic acid, phthalic acid, itaconic acid, citraconic acid, alkenylsuccinic acid, cis-1,2,3,6 tetrahydrophthalic acid, (Meth) acrylic acid compound may be selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, vinyl acetate, methyl-acrylic acid, ethyl-acrylic acid, butyl-acrylic acid, methyl-methacrylic acid, And silane coupling agents may be vinyltrimethoxysilane, vinyltriethoxysilane, gamma-metaacryloxypropyltrimethoxysilane, gamma-acroxypropyltrimethoxy Silane, and acroxymethyltrimethoxysilane.

Since the ethylene vinyl acetate resin composition includes the electron beam modification aid, it is possible to increase the efficiency of electron beam irradiation, and the introduction of the polar group enables the production of ethylene vinyl acetate having an improved integrated adhesion and improved mechanical properties such as melt strength and shear thinning index can do. The photoreactive monomer may be added in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the ethylene vinyl acetate resin composition.

As the reaction aid, a peroxide type crosslinking agent and a crosslinking aid may be used. Examples of the peroxide crosslinking agent include dicumyl peroxide, 1,1-di- (tert-butylperoxy) -3,3,5-trimethylcyclohexane, di- (2-tert-buty-peroxyisopropyl) (2,4-dichlorobenzoyl) -peroxide, di- (2,4-dichlorobenzoyl) -peroxide, dibenzoyl peroxide Butyl peroxybenzoate, tert-butyl cumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexane, di- Dimethyl-2,5-di (tert-butylperoxy) hex-3 or a mixture thereof. Examples of the crosslinking aid include triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylpropane trimethacrylate, divinylbenzene, ethylene glycol dimethacrylate, pentaerythritol triacrylate, Trimethylol propane triacrylate, triaryl isocyanurate, or a mixture thereof.

The ethylene vinyl acetate resin composition may further contain, in addition to the ethylene vinyl acetate resin, an ethylene copolymer including ethylene vinyl acetate copolymer, metallocene polypropylene, metallocene polyethylene, Ziegler-Natta polyethylene, low density polyethylene (LDPE) Polyethylene (LLDPE), high density polyethylene (HDPE), a thermoplastic polyethylene elastomer, a thermoplastic polyethylene plastomer, or a mixture thereof.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a process for producing ethylene vinyl acetate, which comprises ethylene vinyl acetate having a high content of vinyl acetate and is excellent in physical properties such as transparency and elasticity, A method of producing ethylene vinyl acetate having a low melt index capable of improving productivity and economy can be provided.

Fig. 1 is a graph showing the molecular weight distribution according to the electron beam irradiation dose in Example 5. Fig.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Experimental Example  1]: Measurement of penetration depth of radiation according to electron beam energy

The irradiation dose of 2.5MeV and 10MeV was irradiated in the vertical direction with a maximum scanning width of 60 kW and the actual irradiation dose according to the penetration depth with respect to the irradiation dose of the 25 KGy reference electron beam energy was measured and shown in Table 1 below.

2.5 MeV 10 MeV Depth (cm) Dose (KGy) Depth (cm) Dose (KGy) 0.00 21.11 0.00 21.20 0.80 24.12 0.80 23.30 1.60 25.00 1.60 24.40 2.40 18.10 2.40 25.00 3.20 1.08 3.20 24.00 4.00 0 4.00 23.80 4.80 0 4.80 20.60 5.60 0 5.60 18.10 6.40 0 6.40 13.60 7.20 0 7.20 8.12 8.00 0 8.00 1.52 8.80 0 8.80 0 9.60 0 9.60 0 10.40 0 10.40 0 11.20 0 11.20 0 12.00 0 12.00 0

As shown in Table 1, the penetration depth at 2.5 MeV was 3.2 cm at maximum, and the maximum penetration depth at 8 MeV was 8 cm. Therefore, it can be confirmed that when the electron beam is irradiated on both sides, it can be irradiated at a depth of 6.4 cm at 2.5 MeV and at a depth of 16 cm from 10 MeV.

[ Example  1]: Melt index according to the content of vinyl acetate and irradiation dose of electron beam

EVA having a melt index of 60 g / 10 min (190 ° C under 2.16 kg) and a vinyl acetate (VA) content of 40%, EVA having a melt index of 30 g / 10 min (190 ° C. under 2.16 kg) and a vinyl acetate content of 33% * After spreading uniformly to a thickness of 3 to 4 cm in a metal tray of 10 cm, the melt index was measured according to the irradiation dose of the electron beam, and is shown in Table 2 below.

Example EVA
thickness
(cm) Electron beam dose (kGy) The melt index
(g / 10 min, @ 190 DEG C, 2.16 kg) 1-1 60MI / 40VA% 3 ~ 4cm 5 9.73 1-2 10 1.99 1-3 15 0.5 1-4 30MI / 33VA% 3 ~ 4cm 5 4.2 1-5 10 1.0

As shown in Table 2, it was confirmed that the ethylene vinyl acetate (EVA) decreased in melt index as the dose of electron beam irradiation was increased.

* Measuring method of melt index: A 2.096 mm orifice is placed in a cylinder of a melt index measuring instrument set at 190 占 폚, and 4 to 5 g of EVA is filled. Put the piston into the cylinder and put a weight of 2.16 kg to load the EVA. Preheat the EVA inside the cylinder for about 5 minutes, measure the amount of EVA passed for 1 minute, and convert it to the amount passed for 10 minutes.

[ Example  2]: content of vinyl acetate and EVA  The melt index

EVA having a melt index of 60 g / 10 min (190 ° C under 2.16 kg) and a vinyl acetate (VA) content of 40% and a EVA having a melt index of 30 g / 10 min (190 ° C. under 2.16 kg) and a vinyl acetate content of 33% The thickness and the weight of the EVA were measured and the EVA melt index was measured after electron beam irradiation. 6.3 cm, and 12 cm when both sides are irradiated.

Example EVA Thickness (cm) Weight (kg) Investigation method Electron beam
Irradiation dose (kGy) After irradiation, the melt index (g / 10 min, @ 190 DEG C, 2.16 kg) 2-1 60MI / 40VA% 6.3 10 section 10 1.0 2-2 7.9 15 section 10 0.9 2-3 12 25 both sides 10 1.3 2-4 12 25 both sides 8 3.0 2-5 30MI / 33VA% 12 25 both sides 5 3.8

[ Example  3]: electron beam To radiation dose  Following EVA of Melt strength  change

40VA% EVA was irradiated with an electron beam at a different dose, and its melt strength (Rheotens 占 170 占 폚) was measured and shown in Table 4 below.

Electron beam dose (kGy) Melt strength (mN) Example 3-1 5 30 Example 3-2 10 135 Example 3-3 15 1200 Comparative Example 3-1 0 4.2

* Measuring method of melt strength (Rheotens® 170 ° C):

The melt strength was measured with a Gottfert Rheotens 71.97 instrument connected to a capillary rheometer. Ethylene vinyl acetate was melted in a capillary barrel having a length of 15 mm at 170 ° C for about 4 minutes and passed through a piston having a length of 32 mm and a diameter of 1.0 mm at a rate of 3 mm per minute. The ethylene vinyl acetate molten resin passed through the orifice was placed at a rate of 3 mm / s ² The melt strength was measured while passing between two rotating wheels that were engaged by an acceleration.

As shown in Table 4, in Comparative Example 3-1 in which the electron beam was not treated, the strength was not sufficient for extrusion, injection, foaming and the like at a melt strength of 4.2 mN. However, EVA of 1 to 3-3 exhibited a melt strength of 30 mN or more, indicating that the EVA exhibited sufficient strength for film forming, extrusion molding, foam molding and the like.

[ Example  4]: electron beam To radiation dose  Following EVA of Shear Mint Index  change

40VA% EVA was irradiated with an electron beam, and a shear thinning index (ARES 占 170 占 폚, 15% strain) was measured and shown in Table 5 below. The Shear Melt Index is the ratio of the viscosity at 1 rad / sec to the viscosity at 100 rad / sec. The higher the Shear Melt Index, the higher the viscosity at lower shear forces and the lower the viscosity at higher shear forces.

Shear Melt Index = (Viscosity at 1 rad / sec) / (Viscosity at 100 rad / sec)

Electron beam dose (kGy) Shear Mint Index Example 4-1 5 4.9 Example 4-2 10 7.1 Example 4-3 15 10.2 Comparative Example 4-1 0 2.6

As shown in Table 5, in Comparative Example 4-1, the shear thinning index was 2.6, and no shearing effect was observed. In Examples 4-1 to 4-3 irradiated with electron beams of 5 to 15 kGy, values of 4.9 to 10.2 And it can be confirmed that the workability is excellent.

[ Example  5]: electron beam To radiation dose  Following PDI  change

The EVA of 40 VA% was irradiated with electron beams at different doses, the molecular weight thereof was measured, and the molecular weight distribution was calculated and shown in Table 6 and FIG. The molecular weight distribution is the number average molecular weight divided by the weight average molecular weight divided by the weight average molecular weight.

Electron beam dose (kGy) PDI Example 5-1 5 11.2 Example 5-2 10 22.9 Example 5-3 15 14.3 Comparative Example 5-1 0 4.8

As shown in Table 6 and Fig. 1, in Examples 5-1 to 5-3 irradiated with an electron beam than EVA not irradiated with an electron beam, not only the PDI value was large, but also the molecular weight distribution was wide and the appropriate mechanical strength and processability Can be secured.

Claims (15)

Irradiating an ethylene vinyl acetate resin composition containing an ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% with an electron beam of 1 to 25 kGy, the ethylene vinyl resin having a melt index of 10 g / 10 min or less Acetate (EVA).
The method according to claim 1,
Before the step of irradiating the electron beam,
Dissolving the ethylene vinyl acetate resin composition in an auxiliary mold to a thickness of 1 to 16 cm; or
And packaging the ethylene vinyl acetate resin composition into a packaging bag. ≪ RTI ID = 0.0 > 11. < / RTI >
3. The method of claim 2,
Wherein the packaging bag is selected from the group consisting of a polyolefin film, a Yarn woven, a paper, a coated paper, a paper with a liner film, and a cloth.
The method of claim 3,
The polyolefin film may be formed of a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), an ultra low density polyethylene (VLDPE), a high density polyethylene (HDPE), a polypropylene (PP), an ethylene elastomer, an ethylene plastomer, And a propylene-based plastomer. The present invention also provides a method for producing ethylene vinyl acetate (EVA).
3. The method of claim 2,
Wherein the total weight of the packaging bag is 1000 kg or less.
The method according to claim 1,
Wherein the electron beam is irradiated on the ethylene vinyl acetate resin composition in a cross-section or on both sides thereof.
The method according to claim 1,
Wherein the ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% has a Rheotens melt strength of 1 mN to 30 mN.
The method according to claim 1,
Wherein the ethylene vinyl acetate resin having a vinyl acetate content of 15 to 50 wt% has a melt index (190 캜, 2.16 kg) of 15 g / 10 min or more.
The method according to claim 1,
Wherein the ethylene vinyl acetate produced has a melt index of 0.01 to 5 g / 10 min.
The method according to claim 1,
Wherein the ethylene vinyl acetate produced has a Rheotens melt strength of 30 mN or higher.
The method according to claim 1,
Wherein the ethylene vinyl acetate produced has an ARES shear thinning index of from 4 to 25.
The method according to claim 1,
Wherein the ethylene vinyl acetate produced has a molecular weight distribution of 10 or more.
The method according to claim 1,
Wherein the ethylene vinyl acetate resin composition further comprises at least one additive selected from the group consisting of a photoreactive monomer, an antioxidant, a slip agent, an antiblocking agent, a UV stabilizer, and a reaction aid.
14. The method of claim 13,
Examples of the photoreactive monomer include acrylic acid, acrylic acid esters, methacrylic acid, methacrylic acid esters, dicarboxylic acid having a double bond, dicarboxylic acid esters having a double bond, dicarboxylic acid anhydride having a double bond, And a silane coupling agent. 2. The method of producing ethylene vinyl acetate (EVA) according to claim 1,
The method according to claim 1,
The ethylene vinyl acetate resin composition may further comprise at least one selected from the group consisting of an ethylene copolymer including an ethylene vinyl acetate copolymer, a metallocene polypropylene, a metallocene polyethylene, a Ziegler-Natta polyethylene, a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE) (HDPE), a thermoplastic polyethylene elastomer, and a thermoplastic polyethylene plastomer. The method of producing ethylene vinyl acetate (EVA) according to claim 1,

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