KR20220026254A - Molded object, sandwich panel using same, and method for manufacturing same - Google Patents

Abstract

The present invention relates to a molded article having a nonwoven fiber aggregate structure comprising two or more nonwoven fiber aggregates. The present invention relates to the molded article and a sandwich panel using the same as a core layer, and method for manufacturing the same, wherein the molded article includes: a polypropylene composite fiber; and a glass fiber, and the polypropylene composite fiber may include polypropylene; and polypropylene grafted with maleic anhydride. The present invention provides the sandwich panel of high rigidity which does not deteriorate mechanical properties.

Description

Molded article, sandwich panel using same, and manufacturing method thereof

The present invention relates to a molded article, a sandwich panel using the same, and a method for manufacturing the same.

A typical sandwich panel has structural rigidity similar to that of a metal panel and is effective in reducing weight, so it is used in various fields such as construction materials.

In such a sandwich panel, a core layer (molded body) is formed between skin layers formed of aluminum, iron, or the like to control the physical properties of the panel. For example, a foamed resin material may be used for the core layer to increase the weight reduction effect of the panel, or a general resin, composite, or balsa wood material may be used to increase the mechanical strength of the panel. However, such a conventional sandwich panel has disadvantages in that it is light-weight and has insufficient mechanical strength.

Typically, attempts have been made to manufacture a sandwich panel by applying polyethylene (PE) foam as the core material, but it is difficult to say that the effect of weight reduction is excellent, and in the event of a fire in a building where the sandwich panel is installed, due to the nature of polyethylene, a thermoplastic resin, it can lead to a large fire. Safety vulnerabilities have been consistently pointed out.

In order to overcome the above problem, research has been continued to secure semi-incombustible performance by adding an inorganic filler during extrusion of polyethylene foam, but even if the combustibility of the core material is reduced by the addition of the inorganic filler, the low heat resistance of polyethylene Due to this, there was still a limit point in which irregularities were generated on the surface or the surface was deformed when exposed to outdoor for a long time.

Therefore, in order to overcome the above limitations, it is possible to secure quasi-non-combustible performance for safety in the event of a fire, and research and development for a core material that does not rapidly deteriorate mechanical properties even when exposed to the outside for a long period of time and a sandwich panel using the same are required. .

Korean Patent Publication No. 10-2004-0052631, Composite Sandwich Panel Board

In order to solve the above problem, the present inventors completed the present invention by researching a sandwich panel having excellent heat resistance, which not only secures semi-incombustible performance in preparation for fire, but also does not show rapid deterioration of mechanical properties during long-term outdoor exposure.

Therefore, it is an object of the present invention to prepare a nonwoven fiber aggregate structure using 'polypropylene composite fiber and glass fiber' instead of 'polyethylene foam and inorganic filler' used as a conventional core material in manufacturing a sandwich panel, thereby securing semi-incombustible performance and It is to provide a molded article, a sandwich panel, and a method for manufacturing the same, which reduce the panel weight and secure heat resistance even under high temperature conditions.

According to a first aspect of the invention,

A molded article having a nonwoven fiber aggregate structure comprising two or more nonwoven fiber aggregates, the molded article comprising: polypropylene composite fibers; and glass fiber; wherein the polypropylene composite fiber comprises: polypropylene; and polypropylene grafted with maleic anhydride; it provides a molded article comprising.

In one embodiment of the present invention, the molded article may include 1 to 60% by weight of polypropylene composite fibers and 40 to 99% by weight of glass fibers based on the total weight of the molded article.

In one embodiment of the present invention, the polypropylene composite fiber may include 91 to 99% by weight of polypropylene and 1 to 9% by weight of maleic anhydride grafted polypropylene based on the total weight of the polypropylene composite fiber. .

In one embodiment of the present invention, the glass fiber is C-glass (C-Glass), E-glass (E-Glass), S-glass (S-Glass), glass wool (Glass-Wool) and these It may be selected from the group consisting of combinations.

According to a second aspect of the invention,

core layer; a skin layer laminated on at least one surface of the core layer; an adhesive layer for adhering the core layer and the skin layer; and a fluorine-based resin coating layer formed on at least one surface of the skin layer, wherein the core layer uses the molded body.

In one embodiment of the present invention, the fluorine-based resin coating layer is polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), fluorinated ethylene-propylene (FEP) ) and may include those selected from the group consisting of combinations thereof.

In one embodiment of the present invention, the mass per unit area of the sandwich panel may be 2.5 to 6.5 kg/m ² .

In one embodiment of the present invention, when the temperature of the sandwich panel is raised from 25°C to 80°C, the reduction in flexural rigidity (%) may be 25 to 36%.

In one embodiment of the present invention, the sandwich panel may have a flexural stiffness of 29 to 40 GPa at 25°C.

In one embodiment of the present invention, the sandwich panel may have a flexural stiffness of 18 to 30 GPa at 80°C.

According to a third aspect of the invention,

a) preparing a polypropylene composite fiber; b) preparing a nonwoven fiber aggregate by mixing the polypropylene composite fiber and glass fiber; c) manufacturing a core layer by performing a needle punching process on the nonwoven fiber assembly at a number of punches per minute of 300 to 1000 times, a moving speed of 1 to 8 m/min, and a punching density of 100 to 500 punches/cm ² ; d) forming an adhesive layer on at least one surface of the core layer; and e) forming a skin layer in which a fluorine-based resin coating layer is formed on at least one surface on the adhesive layer.

In one embodiment of the present invention, step a) comprises a polypropylene chip; and a polypropylene chip grafted with maleic anhydride; it may be a step of spinning polypropylene composite fibers by blending.

The sandwich panel according to the present invention improves heat resistance by including polypropylene composite fibers when manufacturing a nonwoven fiber aggregate structure used as a core material, and provides excellent semi-incombustible performance by adding glass fibers. In addition, although the formability is improved by using a nonwoven fiber assembly as a core material and the panel is lightened due to a porous structure, there is provided a sandwich panel of high rigidity in which mechanical properties are not deteriorated.

The sandwich panel having the above effect is suitable for use in interior and exterior boards for construction, structural materials for home appliances (TV back covers, washing machine boards, etc.), interior and exterior materials for automobiles, interior and exterior materials for trains/ships/aircraft, various partition boards, elevator structural materials, etc. .

1 is a schematic diagram of a sandwich panel according to a preferred embodiment 1 of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a molded article and a sandwich panel according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As a result of the experiments of the present inventors, the core material used in conventional sandwich panels is very vulnerable to fire by applying polyethylene foam, and even if inorganic fillers are added, there is a problem that deformation such as irregularities occurs on the surface during long-term outdoor exposure. .

In order to solve the above problems, the inventors of the present invention improve heat resistance by preparing a polypropylene composite fiber-based nonwoven fiber assembly instead of extrusion of polyethylene foam when manufacturing a molded article having a nonwoven fiber aggregate structure used as a core material. At the same time, it led to the invention of a molded article securing semi-incombustible performance by adding glass fiber instead of an inorganic filler, a sandwich panel using the same, and a manufacturing method thereof.

molded body

The molded article according to the present invention is a molded article having a nonwoven fiber aggregate structure including two or more nonwoven fiber aggregates, wherein the molded article comprises: polypropylene composite fibers; and glass fiber; wherein the polypropylene composite fiber comprises: polypropylene; and polypropylene grafted with maleic anhydride.

In the present invention, the 'nonwoven fiber aggregate structure' is a structure in which two or more nonwoven fiber aggregates are bonded, and the 'nonwoven fiber aggregate' refers to a nonwoven fiber on a web or a sheet by bonding with an adhesive or , refers to a thing bonded using a thermoplastic fiber, and since the molded article according to the present invention has a nonwoven fiber aggregate in which the fibers are entangled with each other, all or part of the fibers are fused by a binder, and thus natural pores are formed in the molded article It is included, and the breathability is improved, and weight reduction can be improved. That is, since the fibers have natural pores formed while being entangled with each other, unlike the case where pores are artificially formed by an additive such as a foaming agent, it is a non-foaming core, so manufacturing costs can be reduced and the foaming process can be omitted. Efficiency can also be increased. Through the structure of the nonwoven fiber aggregate, moldability and processability may be improved compared to conventional thermoplastic or thermosetting foamed resins.

The molded body includes polypropylene composite fibers. The polypropylene composite fiber is polypropylene (PP); and maleic anhydride grafted polypropylene (MA-g-PP).

As the polypropylene (PP), those commonly used in the industry may be used. The polypropylene may be blended into the polypropylene chip grafted with maleic anhydride when spinning polypropylene composite fibers in the form of chips.

The maleic anhydride-grafted polypropylene (MA-g-PP) may be prepared by copolymerizing polypropylene having a molecular weight of 100,000 to 500,000 and maleic anhydride. The maleic anhydride-grafted polypropylene (MA-g-PP) may be prepared by copolymerizing polypropylene and maleic anhydride in a weight ratio of 70:30 to 90:10. When the above weight ratio is satisfied, mechanical properties such as flexural rigidity may be improved.

In contrast to the case of using only polypropylene as the molded article used for the core layer, when using the polypropylene composite fiber including polypropylene and maleic anhydride grafted polypropylene together, bonding strength between glass fibers and polypropylene to increase the correspondence between fibers.

The polypropylene composite fiber may comprise 91 to 99% by weight, preferably 93 to 98% by weight, more preferably 95 to 97% by weight of polypropylene based on the total weight of the polypropylene composite fiber. When the above weight ratio is satisfied, a polypropylene-based nonwoven fiber aggregate structure compared to the existing polyethylene foam may be used as a core material to have light weight and excellent heat resistance through a porous structure.

The polypropylene composite fiber may include 1 to 9% by weight, preferably 2 to 7% by weight, more preferably 3 to 5% by weight of maleic anhydride grafted polypropylene based on the total weight of the polypropylene composite fiber. there is. When the above weight ratio is satisfied, mechanical properties such as flexural rigidity and flexural modulus can be improved by improving the bonding force between the glass fiber and the polypropylene composite fiber.

The molded body includes glass fibers.

The glass fiber is intended to replace the inorganic filler added to the conventional core material, and has the effect of securing semi-incombustible performance to the polypropylene composite fiber-based nonwoven fiber assembly.

The molded article may have improved dimensional stability under various temperature and humidity conditions compared to the core material of the conventional thermoplastic or thermosetting foam due to the addition of glass fibers. In addition, in the event of a fire, even after ignition, the shrinkage or melting of the molded body may have insignificant effects.

The glass fiber may be selected from the group consisting of C-Glass, E-Glass, S-Glass, Glass-Wool, and combinations thereof. , preferably E-glass (E-Glass).

The molded article may include 1 to 60 wt%, preferably 15 to 55 wt%, more preferably 30 to 50 wt% of polypropylene composite fibers based on the total weight of the molded article. When the above weight ratio is satisfied, a nonwoven fiber assembly based on polypropylene composite fiber is manufactured to maintain the formability of the core layer, and mechanical properties are not rapidly deteriorated even when exposed to the outside for a long period of time or under high temperature conditions. It is possible to prevent the occurrence of irregularities or deformation.

The molded body may include 40 to 99% by weight, preferably 45 to 85% by weight, and more preferably 50 to 70% by weight of glass fibers based on the total weight of the molded body. When the above weight ratio is satisfied, it is possible to prevent the spread of fire when the sandwich panel is constructed by securing improved semi-incombustible performance through the addition of glass fiber.

The binder included in the core layer is not particularly limited as long as it has a structure capable of bonding a nonwoven fiber aggregate on a web or a sheet.

All or part of the polypropylene composite fibers included in the molded article according to the present invention may be fused by the binder, and the binder may have a melting point of 130° C. or higher.

The molded article having a nonwoven fiber aggregate structure according to the present invention has an apparent density of 0.1 to 0.8 g/cm ³ . Since it satisfies the above density range, it may have sufficient mechanical strength for use in building exterior materials and the like.

Since the molded article according to the present invention satisfies the mechanical strength as described above, it is included as a core layer in a sandwich panel, so that the interior and exterior boards for construction, structural materials for home appliances (TV back cover, washing machine board, etc.), interior and exterior materials for automobiles, and trains /Can be used as interior and exterior materials for ships/aircraft (boards such as partitions), boards for various partitions, and elevator structural materials.

In addition, the molded article according to the present invention may further include fillers such as carbon fibers and polymer fibers. In addition, a non-halogen-based flame retardant may be further included. In addition to this, additives such as impact modifiers, heat stabilizers, and antioxidants may be further included.

Manufacturing method of molded body

The manufacturing method of the molded article according to the present invention may be manufactured by the following method.

The manufacturing method of the molded article according to the present invention comprises the steps of: a) preparing a polypropylene composite fiber; b) preparing a nonwoven fiber aggregate by mixing the polypropylene composite fiber and glass fiber; c) performing a needle punching process of 300 to 1000 punchings per minute, a moving speed of 1 to 8 m/min, and a punching density of 100 to 500 punches/cm ² to the nonwoven fiber assembly to prepare a core layer (molded body); includes

In step a), (A) polypropylene and (B) maleic anhydride grafted polypropylene may be prepared in order to prepare polypropylene composite fibers first.

Specifically, step a) may include (A) a polypropylene chip; and (B) maleic anhydride grafted polypropylene chips; may be a step of spinning polypropylene composite fibers by blending them. In the spinning step, a non-halogen-based flame retardant may be prescribed. By adding a non-halogen-based flame retardant during fiber spinning so that the polymer resin does not burn easily during combustion, the flame retardant performance of the molded article, which is a nonwoven fiber aggregate structure, can be improved. The non-halogen-based flame retardant may preferably be a phosphoric acid ester-based flame retardant.

At this time, based on the total weight of the polypropylene composite fiber (A) 91 to 99% by weight, preferably 93 to 98% by weight, more preferably 95 to 97% by weight of polypropylene and (B) 1 to 9% by weight , preferably 2 to 7% by weight, more preferably 3 to 5% by weight of maleic anhydride grafted polypropylene may be mixed and used. When the content of (A) polypropylene and (B) maleic anhydride-grafted polypropylene does not satisfy the above range, the bonding force between the glass fiber and the polypropylene composite fiber may decrease, and mechanical properties of the molded article may be deteriorated.

In step b), (D) glass fiber may be mixed with (C) polypropylene composite fiber prepared in step a) to prepare a nonwoven fiber aggregate. At this time, based on the total weight of the molded article (C) 1 to 60% by weight, preferably 15 to 55% by weight, more preferably 30 to 50% by weight of polypropylene composite fibers and (D) 40 to 99% by weight, preferably Preferably, 45 to 85% by weight, more preferably 50 to 70% by weight of glass fibers may be mixed to prepare a nonwoven fiber aggregate. If the content of the (C) polypropylene composite fiber and (D) glass fiber does not satisfy the above range, the quasi-noncombustible performance is deteriorated even if it has excellent heat resistance when exposed to the outside for a long period of time, or, conversely, the flammability in case of fire is lowered. A molded body for a sandwich panel core material having excellent incombustibility performance but poor heat resistance can be manufactured.

Thereafter, in step c), a needle punching process of 300 to 1000 punches per minute, a moving speed of 1 to 8 m/min, and a punching density of 100 to 500 punches/cm ² is performed on the nonwoven fiber assembly to form a nonwoven fiber assembly structure. can be manufactured.

In the needle punching process, the number of punches per minute is 300 to 1000 times per minute for the mixed nonwoven fiber assembly, the movement speed of the nonwoven fiber assembly is 1 to 8 m/min, and the punching density is 100 to 500 punches/cm ² , A needle punching process may be performed, and more preferably, the number of punches per minute is 400 to 700 times per minute, the movement speed of the nonwoven fiber assembly is 1.5 to 6 m/min, and the punching density is 200 to 400 punches/cm ² to proceed with the needle punching process.

If the number of punches per minute is less than 300, there is a problem in that the degree of binding between the nonwoven fiber aggregates is lowered, and if the number of punchings per minute is more than 1000 times, there is a problem in that the nonwoven fiber aggregate is broken. In addition, if the moving speed of the nonwoven fiber aggregate is slower than 1 m/min, there is a problem in that the production speed is too slow, and if it is faster than 8 m/min, there is a problem in that it is not easy to control the punching density. In addition, when the punching density is less than 100 punches/cm ² , there is a problem in that the degree of binding between the nonwoven fiber aggregates is lowered, and when the punching density is more than 500 punches/cm ² , there is a problem in that the nonwoven fiber aggregate is broken.

The needle punching process may be performed two or more times. When the needle punching process is performed two or more times, it is possible to increase the binding force of the interlayer fibers, which is effective in preventing delamination.

As the needle punching process in the above range is performed, the physical bonding force by needle punching is improved, and physical properties such as tensile strength of the molded body used as the core layer are improved, and through this, the shear stiffness strength and sag of the finally manufactured sandwich panel degree can be improved.

Specifically, after adding and mixing glass fibers to the polypropylene composite fiber, carding is performed using a carding machine, and then a needle punching process of the above conditions is performed to aggregate a nonwoven fiber having a basis weight of 600 to 2400 gsm (nonwoven fabric) to manufacture

After that, the manufactured nonwoven fiber aggregate (nonwoven fabric) is mounted on a plurality of unwinding devices, and then moved to a hot press. At this time, after mounting 1 to 10 manufactured nonwoven fiber aggregates in a plurality of unwinding devices according to the number, it may be moved to a hot press for manufacturing a molded body. When a plurality of nonwoven fiber aggregates are used by using a plurality of unwinding devices in this way, since the thickness of each nonwoven fiber aggregate becomes thin, the length of the nonwoven fiber aggregate wound around one unwinding device becomes longer. Therefore, since it is possible to reduce the number of times of use of the softener for connecting the nonwoven fiber aggregates continuously input during the continuous process, there is an advantage that the process can be simplified.

Thereafter, the plurality of nonwoven fiber aggregates (nonwoven fabrics) moved by the hot press are heated and pressed under a temperature condition of 170 to 210° C. and a pressure condition of 1 to 10 MPa to prepare a molded body having a nonwoven fiber aggregate structure.

The heating press is not particularly limited as long as it is commonly used in the industry, and as a specific example, a double belt press or the like may be used.

In addition, the manufacturing method of the molded article according to the present invention,

After performing the needle punching process of step c), preheating for 3 to 10 minutes at a temperature of 160 to 210° C. may be further included.

sandwich panel

1, the core layer 100; a skin layer 300 laminated on at least one surface of the core layer; an adhesive layer 200 for adhering the core layer and the skin layer; and a fluorine-based resin coating layer 400 formed on at least one surface of the skin layer, wherein the core layer uses the molded body.

The core layer of the sandwich panel according to the present invention is composed of the above-described molded body according to the present invention. The thickness of the core layer is preferably 0.5 to 10 mm. If the thickness is less than 0.5 mm, there is a problem in that it is difficult to maintain excellent mechanical strength, and if the thickness exceeds 10 mm, there is a problem in that the formability is deteriorated during bending or deep drawing molding of the sandwich panel.

The sandwich panel according to the present invention includes a skin layer laminated on at least one surface of the core layer.

The skin layer of the sandwich panel according to the present invention may be formed of a metal material, and may include at least one selected from the group consisting of aluminum, iron, stainless steel (SUS), magnesium, and electrogalvanized steel sheet (EGI). and preferably aluminum or electrogalvanized steel (EGI). For example, in order to have excellent formability and flexural rigidity, a skin layer including an electrogalvanized steel sheet (EGI) may be applied to the sandwich panel. In addition, a skin layer including aluminum may be applied to the sandwich panel in order to reduce the weight.

The thickness of the skin layer may be 0.2 to 2 mm. The skin layer of the conventional sandwich panel had a problem in that the thickness of the skin layer had to be thick due to the low mechanical strength of the core material, thereby increasing the weight of the sandwich panel. Although the thickness is within the above range, it is possible to reduce the weight without rapidly lowering the mechanical properties.

The sandwich panel according to the present invention includes an adhesive layer for bonding the core layer and the skin layer.

The adhesive layer of the sandwich panel according to the present invention is applied between the core layer and the skin layer to adhere the core layer and the skin layer. The adhesive layer is preferably applied with a uniform thickness in consideration of the viscosity. In the present invention, a sandwich panel may be manufactured by laminating the core layer and the skin layer and then curing, or the core layer and the skin layer may be laminated and then thermocompressed to manufacture a sandwich panel. In this case, as the adhesive penetrates into the core layer during curing or thermocompression bonding, there is an effect of improving the adhesion between the skin layer and the core layer by mechanical bonding as well as chemical bonding with the components constituting the core layer. The chemical bonding means that the adhesive becomes a covalent bond with the upper surface and the lower surface of the core layer, a hydrogen bond, a van der Waals bond, an ionic bond, and the like.

The mechanical bonding refers to a form in which the rings are physically hung as if they were hung with each other while the adhesive permeated into the core layer. This form is also called mechanical interlocking. Due to the natural pores contained in the core layer, the adhesive permeates the upper and lower surfaces of the core layer.

The adhesive constituting the adhesive layer may include at least one of an olefin-based adhesive, a urethane-based adhesive, an acrylic adhesive, and an epoxy-based adhesive. The olefin-based adhesive may be at least one selected from the group consisting of polyethylene, polypropylene, and amorphous polyalphaolefin adhesives. The urethane-based adhesive may be used without limitation as long as it is an adhesive including a urethane structure (-NH-CO-O-). The acrylic adhesive may include at least one of a polymethyl methacrylate adhesive, a hydroxyl group-containing polyacrylate adhesive, and a carboxy group-containing polyacrylate adhesive. The epoxy adhesive includes at least one of bisphenol-A type epoxy adhesive, bisphenol-F type epoxy adhesive, novolak epoxy adhesive, linear aliphatic epoxy resins, and cycloaliphatic epoxy resins. may include

In addition, the adhesive may include a photocurable adhesive, a hot melt adhesive, or a thermosetting adhesive, and any one of a photocuring method and a thermosetting method may be used. For example, a sandwich panel can be manufactured by thermosetting a laminate including a skin layer, a core layer, and an adhesive. The thermosetting may be performed for about 5 minutes to 2 hours at 50 to 110° C., which is the curing temperature of the epoxy resin, and curing may be performed for about 1 to 10 hours even at room temperature.

The adhesive layer may be applied to a thickness of about 20 to 300 μm, but is not limited thereto.

As a method of applying the adhesive layer to one surface of the skin layer, any one method selected from among a die coating method, a gravure coating method, a knife coating method, and a spray coating method may be used.

The sandwich panel according to the present invention includes a fluorine-based resin coating layer formed on at least one surface of the skin layer. The fluorine-based resin coating layer may be formed to a thickness of 5 to 100 μm, but is not particularly limited thereto. By forming a fluorine-based resin coating layer on one surface of the skin layer, even when the sandwich panel is exposed to the outside for a long period of time, excellent weather resistance, corrosion resistance and abrasion resistance prevent deterioration of the mechanical properties of the sandwich panel and enable long-term use without replacement. there is.

The fluorine-based resin coating layer is from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), fluorinated ethylene-propylene (FEP), and combinations thereof. It may include selected ones, preferably polyvinylidene fluoride (PVDF).

The mass per unit area of the sandwich panel may be 2.5 to 6.5 kg/m ² , preferably 3 to 6 kg/m ² , and more preferably 3.5 to 5.5 kg/m ² . The sandwich panel may be lightweight due to the porous structure of the nonwoven fiber aggregate used for the core layer, and may have excellent sound absorption performance due to the open-cell type pore structure.

In this case, based on semi-noncombustible standards (total heat release of 8MJ/m ² or less, and peak heat release rate of 200 kW/m ² or less according to ISO 5660-1) and flexural strength standards (KS F 4737, flexural strength of 90N/mm ² or more, It is desirable to reduce the weight while satisfying the 4mm panel thickness standard). When the range of the mass per unit area is satisfied, there is an effect that the sandwich panel can be made lighter in weight compared to the prior art while simultaneously securing semi-incombustible performance and flexural strength.

The sandwich panel may have a flexural stiffness of 29 to 40 GPa, preferably 29 to 35 GPa, more preferably 29 to 33 GPa at 25°C. The flexural stiffness at 25° C. is a value measured according to ASTM C393, and when the above range is satisfied, even though the sandwich panel is lightweight, it has the effect of having mechanical properties suitable for multi-purpose use such as exterior materials for construction.

The sandwich panel may have a flexural stiffness of 18 to 30 GPa, preferably 18 to 25 GPa, more preferably 18 to 22 GPa at 80°C. The flexural stiffness at 80°C is a value measured in accordance with ASTM C393, and when the above range is satisfied, the mechanical properties of the sandwich panel do not rapidly deteriorate even under high temperature conditions. It has a suitable effect to be used as

When the temperature of the sandwich panel is raised from 25°C to 80°C, the reduction in flexural rigidity (%) may be 25 to 36%, preferably 28 to 36%, more preferably 30 to 36%. Through the decrease in flexural rigidity (%) when the temperature is raised from 25° C. to 80° C., the deterioration of mechanical properties according to temperature change, that is, heat resistance, which means the ability of a material to withstand high temperatures without permanent change, can be evaluated. If the flexural stiffness reduction rate (%) in the above range is satisfied, heat resistance to withstand severe conditions is secured due to a sudden change in external temperature after sandwich panel construction, so that the sandwich panel can be used in various temperature and climatic conditions. there is an effect

Sandwich panel manufacturing method

The sandwich panel according to the present invention is formed by sequentially stacking the skin layer 300 , the core layer 100 , and the skin layer 300 , and a fluorine-based resin coating layer 400 is formed on at least one surface of the skin layer 300 . is formed, and is manufactured by applying the adhesive layer 200 between the core layer 100 and the skin layer 300 . After the above components are laminated, the curing and pressing steps may be performed, but the present invention is not limited thereto.

Specifically, the method for manufacturing a sandwich panel according to the present invention comprises:

a) preparing a polypropylene composite fiber; b) preparing a nonwoven fiber aggregate by mixing the polypropylene composite fiber and glass fiber; c) manufacturing the core layer by performing a needle punching process on the nonwoven fiber assembly at a number of punches per minute of 300 to 1000 times, a moving speed of 1 to 8 m/min, and a punching density of 100 to 500 punches/cm ² ; d) forming an adhesive layer on at least one surface of the core layer; and e) forming a skin layer in which a fluorine-based resin coating layer is formed on at least one surface on the adhesive layer.

The core layer of the sandwich panel according to the present invention is composed of the above-described molded body according to the present invention. Accordingly, steps a), b), and c) are the same as the above-described method for manufacturing the molded body.

Thereafter, in step d), an adhesive layer may be formed on at least one surface of the core layer.

The adhesive constituting the adhesive layer may include at least one of an olefin-based adhesive, a urethane-based adhesive, an acrylic adhesive, and an epoxy-based adhesive. The olefin-based adhesive may be at least one selected from the group consisting of polyethylene, polypropylene, and amorphous polyalphaolefin adhesives. The urethane-based adhesive may be used without limitation as long as it is an adhesive including a urethane structure (-NH-CO-O-). The acrylic adhesive may include at least one of a polymethyl methacrylate adhesive, a hydroxyl group-containing polyacrylate adhesive, and a carboxy group-containing polyacrylate adhesive. The epoxy adhesive includes at least one of bisphenol-A type epoxy adhesive, bisphenol-F type epoxy adhesive, novolak epoxy adhesive, linear aliphatic epoxy resins, and cycloaliphatic epoxy resins. may include

In addition, the adhesive may include a photocurable adhesive, a hot melt adhesive, or a thermosetting adhesive, and any one of a photocuring method and a thermosetting method may be used. For example, a sandwich panel can be manufactured by thermosetting a laminate including a skin layer, a core layer, and an adhesive. The thermosetting may be performed for about 5 minutes to 2 hours at 50 to 110° C., which is the curing temperature of the epoxy resin, and curing may be performed for about 1 to 10 hours even at room temperature.

The adhesive layer may be applied to a thickness of about 20 to 300 μm, but is not limited thereto.

As a method of applying the adhesive layer to one surface of the skin layer, any one method selected from among a die coating method, a gravure coating method, a knife coating method, and a spray coating method may be used.

Thereafter, in step e), a skin layer in which a fluorine-based resin coating layer is formed on at least one surface may be formed on the adhesive layer. In this case, referring to FIG. 1 , one surface of the skin layer in direct contact with the adhesive layer may be an opposite surface to one surface of the skin layer on which the fluorine-based resin coating layer is formed.

The fluorine-based resin coating layer may be formed on one side of the skin layer exposed to the outside, and even if the sandwich panel is exposed to the outside and used, the weather resistance, corrosion resistance and abrasion resistance are improved by the formation of the fluorine-based resin coating layer, after the sandwich panel is constructed It has the effect of extending the life of use.

The fluorine-based resin coating layer is from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), fluorinated ethylene-propylene (FEP), and combinations thereof. It may include selected ones, preferably polyvinylidene fluoride (PVDF).

The fluorine-based resin coating layer may be formed to a thickness of 5 to 100 μm, but is not particularly limited thereto.

The skin layer of the sandwich panel according to the present invention may be formed of a metal material, and preferably, any one or more selected from the group consisting of aluminum, iron, stainless steel (SUS), magnesium, and electrogalvanized steel sheet (EGI). may include For example, in order to have excellent formability and flexural rigidity, a skin layer including an electrogalvanized steel sheet (EGI) may be applied to the sandwich panel. In addition, a skin layer including aluminum may be applied to the sandwich panel in order to reduce the weight.

In order to form the skin layer on the adhesive layer, any one of a photocuring method, a thermosetting method, and a thermocompression bonding method may be used. For example, a sandwich panel may be manufactured by thermosetting or thermocompression bonding a laminate including a skin layer, a core layer, and an adhesive.

The thermosetting may be performed for about 5 minutes to 2 hours at 50 to 110° C., which is the curing temperature of the epoxy resin, and curing may be performed for about 1 to 10 hours even at room temperature.

As described above, the sandwich panel according to the present invention is lightweight and uses a core layer with good mechanical properties, so that it not only has excellent mechanical strength and formability, but also has excellent heat resistance because its flexural rigidity does not decrease rapidly even at room temperature and high temperature conditions Do,

In addition, due to the above effects of the sandwich panel, interior and exterior boards for construction, structural materials for home appliances (TV back cover, washing machine board, etc.), interior and exterior materials for automobiles, interior and exterior materials for trains/ships/aircraft (boards such as partitions), various partitions It is suitable for use as a board, elevator structure, etc.

Hereinafter, preferred examples are presented to help the understanding of the present invention, but the following examples are provided for easier understanding of the present invention, and the present invention is not limited thereto.

Example: Preparation of Sandwich Panels

Preparation of core layer (molded body): Preparation Examples 1 to 3

[Production Example 1]

After preparing a polypropylene (PP) chip (Lotte Chemical) and a polypropylene (MA-g-PP) chip grafted with maleic anhydride (polypropylene and maleic anhydride grafted in an 80:20 ratio), these were 95:5 Polypropylene composite fibers were spun by blending in a weight ratio of

After spinning, the polypropylene composite fiber was mixed with glass fiber E-Glass (Owen Corning, SE4121) in a weight ratio of 40:60.

After mixing the fibers, carding is performed using a carding machine, the number of punches per minute is 500 times, the moving speed of the nonwoven fiber aggregate is 2 m/min, and the punching density is 200 punches/cm ² Needle punching process A nonwoven fiber aggregate (nonwoven fabric) having a basis weight of 1500 gsm was prepared through the

After the nonwoven fiber assembly is mounted on two unwinding devices, the number of punches per minute is 500 times, the movement speed of the nonwoven fiber assembly is 2 m/min, and the punching density is 200 punches/cm ² The needle punching process is repeated. Physical recombination was formed between the nonwoven fiber aggregates.

The non-woven fiber aggregate bonded by needle punching was preheated for 3 minutes after entering the preheating chamber having a chamber temperature of 210°C.

Thereafter, the nonwoven fiber aggregate was transferred to a double belt press at a speed of 5 m/min. At this time, the heating temperature of the double belt press was 200° C. and the pressure was 5 MPa, and a core layer (molded body) having a nonwoven fiber aggregate structure was prepared by heating/pressing treatment for 10 minutes.

[Production Example 2]

A polyethylene foam composition was prepared by mixing polyethylene (PE) and a foaming agent. While extruding the polyethylene foam composition, magnesium hydroxide (Mg(OH) ₂ ) as an inorganic filler was added to prepare a core layer (molded body). When the core layer was manufactured, the weight ratio of polyethylene and inorganic filler was 30:70.

[Production Example 3]

With respect to the polypropylene composite fiber, polyethylene terephthalate fiber (PET) (Daeyang Industrial, Super A) instead of glass fiber was mixed in a weight ratio of 40:60 to prepare a nonwoven fiber assembly in the same manner as in Preparation Example 1 , a core layer (molded body) having a nonwoven fiber aggregate structure was prepared.

Preparation of Sandwich Panels: Example 1 and Comparative Examples 1 and 2

[Example 1]

On both sides of the core layer prepared in Preparation Example 1, a polyolefin adhesive (Samsung Gratech) was applied to a thickness of 50 μm. In addition, after preparing a 0.5 mm thick aluminum plate (Dongbu Steel, 3003H32) coated on one side to a thickness of 25 μm with polyvinylidene fluoride (PVDF) as a skin layer, it is laminated on the applied adhesive layer, and the laminated result is After heat curing at 130° C., a sandwich panel having a thickness of 4 mm was finally prepared.

[Comparative Example 1]

A sandwich panel was manufactured in the same manner as in Example 1, except that the core layer prepared in Preparation Example 2 was used.

[Comparative Example 2]

A sandwich panel was manufactured in the same manner as in Example 1, except that the core layer prepared in Preparation Example 3 was used.

Experimental Example 1: Heat resistance evaluation of sandwich panels

After preparing the same 4 mm thick sandwich panel prepared in Example 1 and Comparative Examples 1 and 2 as a specimen, the flexural stiffness was measured at room temperature (25°C) and high temperature (80°C) conditions according to ASTM C393 did. The measurement results are shown in Table 1 below.

Flexural stiffness at 25°C (GPa) Flexural stiffness at 80℃ (GPa) Flexural stiffness reduction rate (%) Example 1 30 20 33 Comparative Example 1 28 12 58 Comparative Example 2 26 16 38

Referring to Table 1, it can be seen that Example 1 has superior flexural rigidity than Comparative Examples 1 and 2 as mechanical properties under the same 25°C or 80°C conditions, respectively.

In addition, in the case of Example 1 including a core layer of a nonwoven fiber aggregate structure prepared by including polypropylene composite fibers instead of polyethylene foam, the flexural rigidity was reduced by only 33% compared to 25 °C even when the temperature was raised to 80 ° C. could confirm that

On the other hand, Comparative Example 1 including polyethylene foam in the core layer had a decrease in flexural rigidity by 58% when the temperature was raised to 80° C., and it was confirmed that the heat resistance was significantly lower than that of Example 1.

Experimental Example 2: Evaluation of semi-incombustible performance of sandwich panel

For Example 1 and Comparative Examples 1 and 2, total heat release and peak heat release rate were measured based on ISO 5660-1, and the results are shown in Table 2 below. it was

Total heat release within 10 minutes (MJ/m ² ) Highest heat dissipation rate (kW/m ² ) Example 1 0.5 1.7 Comparative Example 1 2 3.4 Comparative Example 2 8.8 (after 5 minutes) 204

Through the measurement results in Table 2, in the case of Example 1, the total heat release within 10 minutes is 8MJ/m ² or less, and the highest heat release rate is 200 kW/m ² or less, so ISO 5660-1 regarding semi-incombustible performance It was confirmed that the sandwich panel satisfies the standard. Through this, it was confirmed that Example 1 exhibited a semi-non-combustible performance equal to or higher than that of Comparative Example 1, in which an inorganic filler was added to secure the semi-incombustible performance of the existing polyethylene foam.

However, in the case of the sandwich panel of Comparative Example 2, even when polypropylene composite fibers are used as binders in the same manner as in Example 1 when manufacturing the nonwoven fiber assembly of the core layer, glass fibers are not included in the above ISO 5660-1 standard. It was confirmed that the semi-nonflammable performance was significantly lower than that of Example 1.

Experimental Example 3: Evaluation of the weight reduction rate of sandwich panels

For Example 1 and Comparative Examples 1 and 2, the weight per unit area was measured based on the same 4 mm thick sandwich panel, and is shown in Table 3 below.

Weight per unit area (kg/m ² ) Example 1 4.3 Comparative Example 1 7.1 Comparative Example 2 4.3

Through the experimental results in Table 3, it can be confirmed that the sandwich panel of Example 1 is a lightweight sandwich panel in which the weight per unit area is reduced by 39% even though it has superior heat resistance and semi-incombustibility performance in Experimental Examples 1 and 2 than in Comparative Example 1. could

Through this, it was found that Example 1 had the effect of reducing the weight of the panel even though the heat resistance and semi-incombustible performance were improved by the addition of the nonwoven fiber aggregate structure and glass fiber based on the polypropylene composite fiber.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will become apparent from the appended claims.

100: core layer
200: adhesive layer
300: skin layer
400: fluorine-based resin coating layer

Claims (12)

A molded article having a nonwoven fiber aggregate structure comprising two or more nonwoven fiber aggregates,
The molded article may include polypropylene composite fibers; and glass fibers; and
The polypropylene composite fiber may include polypropylene; and a polypropylene grafted with maleic anhydride.
The method of claim 1,
The molded body is based on the total weight of the molded body
1 to 60% by weight of polypropylene composite fibers and
40 to 99% by weight of glass fibers.
The method of claim 1,
The polypropylene composite fiber is based on the total weight of the polypropylene composite fiber.
91 to 99% by weight of polypropylene and
A molded article comprising 1 to 9% by weight of maleic anhydride grafted polypropylene.
The method of claim 1,
The glass fiber is selected from the group consisting of C-glass (C-Glass), E-glass (E-Glass), S-glass (S-Glass), glass wool (Glass-Wool), and combinations thereof, molded body.
core layer;
a skin layer laminated on at least one surface of the core layer;
an adhesive layer for adhering the core layer and the skin layer; and
Including; a fluorine-based resin coating layer formed on at least one surface of the skin layer;
A sandwich panel, wherein the core layer uses the molded body of claim 1 .
6. The method of claim 5,
The fluorine-based resin coating layer is from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), fluorinated ethylene-propylene (FEP), and combinations thereof. A sandwich panel comprising a selection.
6. The method of claim 5,
A mass per unit area of the sandwich panel is 2.5 to 6.5 kg/m ² , a sandwich panel.
6. The method of claim 5,
The sandwich panel has a reduction in flexural stiffness (%) of 25 to 36% when the temperature is raised from 25°C to 80°C.
6. The method of claim 5,
The sandwich panel has a flexural stiffness of 29 to 40 GPa at 25°C.
6. The method of claim 5,
The sandwich panel has a flexural stiffness of 18 to 30 GPa at 80°C.
a) preparing a polypropylene composite fiber;
b) preparing a nonwoven fiber aggregate by mixing the polypropylene composite fiber and glass fiber;
c) manufacturing a core layer by performing a needle punching process on the nonwoven fiber assembly at a number of punches per minute of 300 to 1000 times, a moving speed of 1 to 8 m/min, and a punching density of 100 to 500 punches/cm ² ;
d) forming an adhesive layer on at least one surface of the core layer; and
e) forming a skin layer in which a fluorine-based resin coating layer is formed on at least one surface on the adhesive layer;
12. The method of claim 11,
Step a) is a polypropylene chip; and a polypropylene chip grafted with maleic anhydride; the step of spinning polypropylene composite fibers by blending, a method for producing a sandwich panel.

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