KR20120002393A - Method of producing highly flowable and flame retardant modified polyethylene powder for metal coating - Google Patents

Abstract

PURPOSE: A manufacturing method of modified polyethylene powder is provided not to generate volatile organic compound during coating film formation, to prevent environment contamination, and to secure the safety of a worker. CONSTITUTION: A manufacturing method of modified polyethylene powder comprises: a step(S10) of manufacturing modified resin by reacting and extruding high density polyethylene which has the high flexability of 60-100 melt index, and 0.5-1.5 parts by weight maleic anhydride on the basis of total modified resin(P1); a step(S20) of manufacturing resin composition(P2) by mixing 10-40 parts by weight the modified resin(P1), 30-85 parts by weight adhesive resin, and 5-30 parts by weight flame retardant; and an additional step(S30) of manufacturing powder by pulverizing the resin composition(P2) to the size of 10-300 micron.

Description

Method of producing modified polyethylene powder for metal coating having high flowability and flame retardancy {Method of producing highly flowable and flame retardant modified polyethylene powder for metal coating}

The present invention relates to a method for producing modified polyethylene powder for metal coating having high fluidity and flame retardancy.

In general, the coating of metal parts aims to prevent the metal parts from oxidizing by finishing the paint on the surface, and to increase durability and aesthetic effect. Conventional liquid paints are a mixture of polymer resins, binders, and pigments in volatile organic solvents. After coating, the coating film is formed by volatilization of organic solvents. Most of the organic solvents used are hazardous substances of VOC. There is a problem that affects directly or indirectly.

On the other hand, conventional thermoplastic powder coatings which do not generate volatile organic compounds are mainly powdered coatings made of non-polar polyolefin such as polyethylene, polypropylene, ethylene vinyl acetate, etc. There is no simple adhesive coating, and if a part of the coating is broken, there is a problem that the lifting phenomenon is easily spread to the entire coating film and the durability is insufficient.

As a characteristic of the powder coating, there is an advantage of forming a coating film having a thickness of 100 to 500 with one coating. However, since the melt flow index is low, the wettability to the coating is poor and the adhesiveness is low, which causes heat and moisture. When coated on metal structures (such as air conditioners, refrigerator rear trays, and outdoor mesh pans) that are frequently exposed to many external environments, the coating may be lifted or cracked, and it may continue to accelerate the rusting of the peeled areas. I have a problem.

In addition, since the powder coating is significantly lower in flowability than the liquid coating, it is difficult to form a uniform coating film. Therefore, when the powder coating is applied to the coating material, it is difficult to constantly adjust the coating film thickness. It is used more limitedly than paints, and powder coatings containing inorganic additives have a high economic burden due to the high incidence of poor coating such as orange peel and pinholes on the surface of the coating film, which requires the use of additives such as leveling agents and surface improving agents. .

Recently, as the amount of paint is increased at home and abroad, there is a growing interest and demand for environmental stability and stability. Accordingly, an environmentally friendly flame retardant composition and powder coating containing the same can exhibit the effects of combustion and delay in the event of a fire. Interest in the situation is increasing.

The present invention is a method of manufacturing a modified polyethylene powder for metal coating having a high flowability and flame retardancy to meet the corrosion protection and aesthetic appearance of the metal and to prevent environmental pollution since no volatile organic compounds occur at all when forming a coating film Promote the safety of workers. In addition, by using modified polyethylene as the main resin, the purpose of the present invention is to improve the adhesive performance, form a smooth coating film according to high fluidity, and to impart flame retardance as compared with the conventional powder coating.

In the method of manufacturing modified polyethylene powder for metal coating of the present invention, 0.5 to 1.5 parts by weight of maleic anhydride of high density polyethylene (HDPE, High Density Polyethylene) having a melt index of 60 to 100 and total modified resin (P1) Reaction extrusion to prepare a modified resin (P1) (S10);

The modified resin (P1) 10 to 40 parts by weight, high density polyethylene (HDPE), low density polyethylene (LDPE, low density polyethylene), linear low density polyethylene (LLDPE, linear low density polyethylene), medium density polyethylene (MDPE, medium density polyethylene) ), Polycarbonate (PC, polycarbonate), ethylene vinyl acetate (EVA, ethylene vinyl acetate), polyethylene terephthalate (PET, polyethylene terephthalate), ethylene propylene diene monomer (EPDM, ethylene propylene diene monomer), styrene butadiene styrene (SBS, Adhesive resin composed of at least one material selected from stylene butadiene stylene (SBR), styrene butadiene rubber (SBR), styrene ethylene butadiene styrene (SEBS), butadiene rubber (BR) It comprises a; step (S20) to produce a resin composition (P2) by mixing ~ 85 parts by weight, and 5 to 30 parts by weight of the flame retardant.

According to the present invention, it satisfies the corrosion protection and aesthetic appearance of the metal and does not generate any volatile organic compounds as in the case of the liquid coating when forming the coating film, thereby preventing environmental pollution and promoting the safety of the worker, and also modified resin polyethylene The present invention provides a method for producing modified polyethylene powder for metal coating having high flowability and flame retardancy, which can improve adhesion performance and form a smooth coating film according to high flowability as compared with conventional powder coating.

1 is a process chart of the modified polyethylene powder for metal coating having a high flowability and flame retardancy of the present invention.

Hereinafter, a method for preparing modified polyethylene powder for metal coating having high fluidity and flame retardancy according to an embodiment of the present invention will be described in detail. 1 is a process chart of the modified polyethylene powder for metal coating having a high flowability and flame retardancy of the present invention.

As shown in FIG. 1, the method of manufacturing modified polyethylene powder for metal coating having high flowability and flame retardancy according to an embodiment of the present invention includes the steps of preparing modified resin (P1) in the first step (S10) and secondly. It comprises a step (S20) of preparing a resin composition (P2), and a step (S30) of preparing a powder in the third.

First, in the step of manufacturing the modified resin (P1) (S10), 0.5 ~ 1.5 weight of the high-density polyethylene (HDPE, High Density Polyethylene) and total modified resin (P1) having a high melt melt index of 60 ~ 100 Reaction extruded negative maleic anhydride.

When maleic anhydride is lower than 0.5 parts by weight, the effect is low when the adhesive is mixed with the adhesive resin, the effect is lowered, more than 1.5 parts by weight of the unreacted substances are generated, rather the effect of the reaction extrusion is reduced.

The reason why the melt index of the first modified resin and the added HDPE is 60 to 100 is high because the flow index is lowered according to manufacturing stages, so that the flow index of the final development composition is in the range of 20 to 40. That is, the reason for using high density polyethylene having a high initial melt index is that the melt index is lowered when the final composition (modified resin + adhesive resin + flame retardant) is prepared to have a melt index of 20 to 40.

Next, in the step of preparing a resin composition (P2) (S20), 10 to 40 parts by weight of the modified resin (P1) prepared in the previous step (S10), high density polyethylene (HDPE), low density polyethylene (LDPE, low density) polyethylene), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), polycarbonate (PC, polycarbonate), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET) , polyethylene terephthalate, ethylene propylene diene monomer (EPDM), styrene butadiene styrene (SBS, stylene butadiene stylene), styrene butadiene rubber (SBR, stylene butadiene rubber), styrene ethylene butadiene styrene (SEBS, styrene etylene butadiene 30 to 85 parts by weight of an adhesive resin composed of at least one material selected from styrene) and butadien rubber (BR), and 5 to 30 parts by weight of a flame retardant. Combined to produce a resin composition (P2). At this time, the mixing is performed using an extruder.

If the primary compound modified resin (P1) is less than 10% by weight, the adhesive strength of the powder coating resin composition is weak and when the weight is more than 40% by weight, the melt index of the powder coating composition including the final flame retardant is lowered due to the excessive increase in the crosslinking degree between the resins. There is a problem in that it is difficult to express uniform melt coating performance.

The adhesive resin agent is mixed with the reaction extruded modified high density polyethylene resin and serves to exhibit adhesiveness and mechanical properties. The reason for reacting the modified high density polyethylene resin alone is to increase the reactivity of the high density polyethylene with maleic anhydride.

Adhesiveness is imparted only when the modified high density polyethylene and the adhesive resin are mixed together. In addition, by using the adhesive resin composition serves to complement the coating properties so that the final product can act as a coating agent.

The flame retardant is preferably an organic mixed flame retardant, the content of the flame retardant of the final product (resin composition (P2)) is 5 to 30 parts by weight, if less than 5 parts by weight, there is a problem of combustion due to lack of flame retardancy, 30 parts by weight The flame retardancy is excellent but has a problem of reducing the coating properties of the coating agent is limited in use. In consideration of flame retardancy and coating properties, it is preferable to adjust the content of the flame retardant to 20 parts by weight or less. Organic mixed flame retardants of melamine polyphosphate (MPP, Melamine poly phosphate phosphorus 14-17%, nitrogen content 40-44%, average particle size 3.5-4.5μm) and Red Phosphate (average particle size 10μm or less) may be used.

Method for producing a modified polyethylene powder for metal coating having a high flowability and flame retardancy according to an embodiment of the present invention, the resin composition (P2) is prepared in the form of pellets, the step of preparing the resin composition (P2) S20), preferably, further comprising the step (S30) of preparing a powder by grinding the resin composition (P2) to 10 ~ 300 μm through the coarsely pulverized / finely ground step.

In the method of manufacturing a modified polyethylene powder for metal coating having high flowability and flame retardancy according to an embodiment of the present invention, the step of preparing the modified resin (P1) (S10), the pellet form of high density polyethylene and powder It is preferable to proceed by grafting maleic anhydride with an extruder at 180-220 degreeC conditions.

The temperature range is a condition under which ethylene of the high density polyethylene is terminated by reaction extrusion and maleic anhydride can be bound. 180 to 220 degrees shows a condition in which the extruder zone from the raw material input part to the reacted part is elevated in stages.

At least one of an antioxidant or an initiator is additionally mixed in the step (S10) of preparing a modified resin (P1) of the modified polyethylene powder for metal coating method having a high fluidity and flame retardancy according to an embodiment of the present invention. It is preferable to be. The antioxidant is one selected from phenol and phosphate compounds, and the initiator is preferably dicumyl peroxide (DCP).

The melt index of the resin composition (P2) according to an embodiment of the present invention of the present invention is preferably 20 to 40. If the melt index of the final product is less than 20, there is a problem of low coating properties due to the lack of flowability and wettability, and high to 40 or more because it is difficult to uniformly adjust the coating film thickness during coating.

In addition, in the step (S20) of preparing the resin composition (P2), the coloring pigment selected from titanium dioxide (carbon dioxide), carbon black (carbon black), phthalocyanine (phthalocyanine) is the total weight of the resin composition (P2) It is preferable that 1 to 5% by weight of is further mixed.

It will be described in more detail with respect to the method of producing a modified polyethylene powder for metal coating having a high flowability and flame retardancy of the present invention.

In the present invention, the melt flow index (MI, 190 degrees, 2.16kg conditions) is 80% high-density polystyrene (HDPE, High Density Polyethylene) has a high fluidity reaction extruded to give adhesion to the maleic anhydride and give it as the main resin use.

In addition, the present invention, in addition to the main resin, high density polyethylene (HDPE, low density polyethylene (LDPE, low density polyethylene), linear low density polyethylene (LLDPE) so as to have a coating characteristic according to the use and required properties , Medium density polyethylene (MDPE), polycarbonate (PC, polycarbonate), ethylene vinyl acetate (EVA, ethylene vinyl acetate), polyethylene terephthalate (PET), ethylene propylene diene monomer (EPDM, ethylene propylene diene monomer), styrene butadiene styrene (SBS), styrene butadiene rubber (SBR, stylene butadiene rubber), styrene ethylene butadiene styrene (SEBS), butadiene rubber (BR, butadien rubber) It manufactures the modified polyethylene resin composition for metal coatings containing the above.

In this case, in addition to maleic anhydride, an initiator, dicumyl peroxide (DCP, dicumyl peroxide) may be added, and the reaction extrusion process of high density polyethylene may include at least one or more of a phenol and a phosphate compound as an antioxidant.

The primary compound (modified resin, P1) manufacturing step of the manufacturing process is to produce a modified high-density polyethylene resin through the reaction extrusion, the primary compound (modified resin) is used to formulate 10 to 40% by weight of the secondary compound desirable.

In addition, in the secondary compounding process of the modified and modified main resin (modified resin) and the resin composition, titanium dioxide and carbon black, which are not chemically reactive and have excellent heat resistance, for coloring the final coating composition. ), And colored pigments such as phthalocyanine may be added in an amount of 1 to 5% by weight of the total weight of the resin composition, and a powder having a size of 1 to 20 μm is preferable.

In the present invention, a flame retardant having a non-mechanical machine was used in order to impart flame retardancy, and as an organophosphorus flame retardant, ammonium polyphosphate (APP, ammonium polyphosphate), melamine phosphate (MP, melamine phosphate), and organic phosphoric acid having a phosphorus content of about 25 to 30% Organophorus ester, melamine polyphosphate (MPP), red phosphate (Red Phosphate) and the like belonging to the group of one or more may be selected, the particle size of the final powder coating composition 50 The particle size of the organophosphorous flame retardant is 1-20 μm in consideration of the fact that it is less than μm, and more preferably 5-10 μm.

In addition, as the inorganic flame retardant, at least one or two or more kinds may be used in the group consisting of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc borate compound, and molybdenum compound, wherein the particle size of the inorganic flame retardant is 1-20 μm, more preferably. Preferably it is 5-10 micrometers.

In addition, calcium carbonate, talc, or the like may be used as the inorganic additive, and the surface hardness of the coating film may be improved.

When the particle size of the organic mixed flame retardant is less than 1, the load in the extruder increases when the main resin and the compound are mixed, and thus, workability may be degraded or uniform dispersion due to agglomeration may be difficult. When the particle size is larger than 20 μm, coating properties may be uneven. It is not preferable because it may cause the appearance quality to deteriorate.

In addition, since the flame retardant has a property of making carbonaceous char difficult to burn during pyrolysis, and can express effective flame retardancy in a smaller amount when mixed, the organic-based mixed flame retardant is used in the present invention.

The non-halogen organic mixed flame retardant is added to 5 to 30% by weight relative to the total composition, preferably 5 to 20% by weight is used. If the content of the flame retardant composition is 5% by weight or less, it is difficult to expect flame retardancy, while if it exceeds 20% by weight, compounding in a twin screw extruder is difficult, which may lower the mechanical properties of the plastic, which is the main resin. .

Finally, the modified high-density polyethylene main resin, resin additive, and flame retardant compound composition are manufactured in pellet form through compounding process, and then used as a powder paint to be coarsely pulverized in the first powdering step through mechanical grinding to obtain 500 μm. In the pulverization, which is the second powdering step, the powder is pulverized to have a particle size in the range of about 10 to 300 μm.

Extrusion process  Content and working condition

Stage 1 : In reaction extrusion  by Main resin  Manufacturing stage

-Content: HDPE and maleic anhydride are grafted using twin screw twin extruder. HDPE itself is nonpolar and non-adhesive. Therefore, grafting with maleic anhydride introduces a polar group (-COOH) into HDPE.

Dicumyl peroxide (DCP), an initiator, breaks down the ethylene bond of HDPE and forms radicals upon reaction extrusion, thereby allowing the polar group of maleic anhydride to be grafted thereto.

HDPE is pellet, maleic anhydride and DCP are mixed in powder form in the hopper of the extruder. The actual manufacturing process is made through a twin screw extruder with two screws, and the working conditions are set to 180 ~ 220 ℃ to raise the temperature from the hopper to the die (inlet).

Step 2: coating composition (resin composition, P2 A) manufacturing steps

-Contents: Since the present invention aims to produce a powder coating agent, the reaction product prepared in step 1 is used as a main resin, and other resins and additives are kneaded to give physical properties as a coating agent, thereby preparing a coating composition. Go through the steps.

In the second stage, the modified high density polyethylene (HDPE) prepared in the first stage, high density polyethylene (HDPE), low density polyethylene (LDPE, low density polyethylene), linear low density polyethylene (LLDPE, linear) to have coating characteristics according to the use and required properties low density polyethylene), medium density polyethylene (MDPE), polycarbonate (PC, polycarbonate), ethylene vinyl acetate (EVA, ethylene vinyl acetate), polyethylene terephthalate (PET), ethylene propylene diene monomer ( EPDM, ethylene propylene diene monomer, styrene butadiene stylene (SBS), styrene butadiene rubber (SBR, stylene butadiene rubber), styrene ethylene butadiene styrene (SEBS), butadiene rubber (BR, butadien rubber) To prepare a modified polyethylene resin composition for metal coating comprising any one or more of Flame retardants, coloring pigments and inorganic additives are added to impart functionality.

Adhesive resins include high density polyethylene (HDPE), low density polyethylene (LDPE, low density polyethylene), linear low density polyethylene (LLDPE, linear low density polyethylene), medium density polyethylene (MDPE, medium density polyethylene), polycarbonate (PC, polycarbonate), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET, polyethylene terephthalate), ethylene propylene diene monomer (EPDM), styrene butadiene styrene (SBS, stylene butadiene stylene), styrene butadiene It is composed of at least one material selected from rubber (SBR, stylene butadiene rubber), styrene ethylene butadiene styrene (SEBS), butadiene rubber (BR, butadien rubber).

The working conditions of the second stage are the same as the first stage and are produced in pellet form because they are manufactured through an extruder.

Step 3: Grinding process for use as modified polyethylene powder coating

-Contents: Steps 1 and 2 above are for preparing pellets by mixing the basic properties of the coating agent with the flame retardant, and this step means grinding to use as a powder coating agent. Grinding is made to 500㎛ or less through the first coarse grinding, and grinding to have a range of 10 ~ 300㎛ through the second fine grinding. Preferably, a modified polyethylene powder coating having a size of 250 μm is prepared.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, the scope of the present invention is not limited to these embodiments, and the scope of the present invention is defined by the following claims, and equivalent scope of the present invention. It will include various modifications and variations belonging to.

The reference numerals set forth in the claims below are merely to aid the understanding of the present invention, not to affect the interpretation of the scope of the claims, and the scope of the claims should not be construed narrowly.

P1: Modified resin, 1st compound
P2: Resin Composition, Secondary Compound

Claims (7)

A step of preparing a modified resin (P1) by reacting and extruding high density polyethylene (HDPE, High Density Polyethylene) having a melt index of 60 to 100 and 0.5 to 1.5 parts by weight of maleic anhydride of the total modified resin (P1). (S10);
The modified resin (P1) 10 to 40 parts by weight, high density polyethylene (HDPE), low density polyethylene (LDPE, low density polyethylene), linear low density polyethylene (LLDPE, linear low density polyethylene), medium density polyethylene (MDPE, medium density polyethylene) ), Polycarbonate (PC, polycarbonate), ethylene vinyl acetate (EVA, ethylene vinyl acetate), polyethylene terephthalate (PET, polyethylene terephthalate), ethylene propylene diene monomer (EPDM, ethylene propylene diene monomer), styrene butadiene styrene (SBS, Adhesive resin composed of at least one material selected from stylene butadiene stylene (SBR), styrene butadiene rubber (SBR), styrene ethylene butadiene styrene (SEBS), butadiene rubber (BR) Containing ~ 85 parts by weight, 5 to 30 parts by weight of the flame retardant to prepare a resin composition (P2); Method for producing a modified polyethylene powder for metal coating, characterized in that. The method of claim 1,
The flame retardant is a method for producing a modified polyethylene powder for metal coating, characterized in that the particle size is 1 ~ 20 μm. The method according to claim 1 or 2,
The resin composition (P2) is prepared in the form of a pellet, after the step of preparing the resin composition (P2) (S20),
Method for producing a modified polyethylene powder for metal coating, characterized in that it further comprises; (S30) to produce a powder by grinding the resin composition (P2) to 10 ~ 300 μm. The method of claim 1,
The step of preparing the modified resin (P1) (S10),
Method for producing a modified polyethylene powder for metal coating, characterized in that the grafting of high density polyethylene in the form of pellets and maleic anhydride on a powder in an extruder at 180 ~ 220 ℃ condition. The method of claim 1,
At least one of an antioxidant or an initiator is further mixed in the step of preparing the modified resin (P1),
The antioxidant is one selected from phenol and phosphate compounds,
Initiator is dicumyl peroxide (DCP, dicumyl peroxide) characterized in that the method for producing a modified polyethylene powder for metal coating. The method according to claim 1 or 2,
Melt index of the resin composition (P2) is a metal coating modified polyethylene powder manufacturing method, characterized in that 20 to 40. The method of claim 1,
In the step of preparing the resin composition (P2) (S20),
Metal pigments, characterized in that 1 to 5% by weight of the total weight of the resin composition (P2) is further mixed with a pigment selected from titanium dioxide, carbon black, and phthalocyanine. How to prepare modified polyethylene powder.

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