KR102127944B1 - Non crosslinked olefin resin composition and foam and method for manufacturing the same - Google Patents

Abstract

Disclosed is a crosslinked olefin resin composition having an increased melt viscosity.
The crosslinked olefin-based resin composition according to the present invention comprises a random polypropylene resin containing 10% by weight or less of ethylene, based on 100% by weight of propylene and ethylene; A high melt strength polypropylene resin having a melt index of 0.5 to 4 g/10 min; Olefin-based elastomers; A fluorine-based polymer resin containing polytetrafluoroethylene; And a crystal nucleating agent.

Description

Non-crosslinked olefin resin composition and foam using the same, and a manufacturing method therefor{NON CROSSLINKED OLEFIN RESIN COMPOSITION AND FOAM AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a foam using a crosslinked olefinic resin composition, and more particularly, to a crosslinked olefinic resin composition and a foam using the same, and a method for manufacturing the foam.

Generally, the foam is manufactured using a crosslinking process or a crosslinking process.

The non-crosslinking process is a method of manufacturing a foam by melting and extruding a volatile solvent and an inorganic foaming agent together with a resin composition under high temperature and high pressure. On the other hand, the crosslinking process is a method of manufacturing a foam by extruding a resin composition and then crosslinking it in various ways. That is, the crosslinking process is different from the non-crosslinking process in that foaming conditions are obtained by adjusting the viscosity of the resin during foaming to the degree of crosslinking.

Foams manufactured through such a crosslinking process or a crosslinking process are used in various fields. In particular, the foam applied to the automobile interior material is produced by foaming after undergoing an electron beam crosslinking or chemical crosslinking process to increase the vehicle's weight and increase the melt viscosity of the resin composition. Such a crosslinking process causes problems such as the necessity of pretreatment, an increase in manufacturing cost, and a decrease in productivity.

On the other hand, foams using a non-crosslinking process are being developed, but there are difficulties in controlling the flow of resin and the processing time.

Accordingly, there is a need for a foam capable of exhibiting effects such as simplification of the manufacturing process and reduction in manufacturing cost without requiring a separate crosslinking process.

Background art related to the present invention is Republic of Korea Patent Registration No. 10-1318403 (2013.10.08. registration), the document discloses a method of manufacturing a double foamed inner skin material for automobile interior materials.

An object of the present invention is to provide a crosslinked olefinic resin composition capable of increasing the melt viscosity of the resin composition.

Another object of the present invention is to provide a foam having improved processing properties and foaming properties and a method for manufacturing the same, using the above-mentioned crosslinked olefin-based resin composition.

The cross-linking olefin-based resin composition according to the present invention for achieving the above object comprises a random polypropylene resin containing 10% by weight or less of ethylene, relative to 100% by weight of propylene and ethylene; A high melt strength polypropylene resin having a melt index of 0.5 to 4 g/10 min; Olefin-based elastomers; A fluorine-based polymer resin containing polytetrafluoroethylene; And a crystal nucleating agent.

The non-crosslinked olefin-based resin composition is based on 100 parts by weight of the random polypropylene resin, 10 to 50 parts by weight of the high melt strength polypropylene resin, 50 to 300 parts by weight of the olefin elastomer, 0.3 to 3 parts by weight of the fluoropolymer resin, and crystals It may contain 0.1 to 2 parts by weight of the nucleating agent.

The olefin-based elastomer may have a melt index of 3-10 g/10 min.

The fluorine-based polymer resin forms small fibers at 120 to 250° C., and the small fibers form a network structure intertwined with the random polypropylene resin, the high-melting-tensile polypropylene resin, and the olefin-based elastomer. May be

The nucleating agent may include talc.

Method for producing a foam according to the present invention for achieving the other object is (a) propylene and 100% by weight of ethylene, random polypropylene resin containing 10% by weight or less of ethylene; A high melt strength polypropylene resin having a melt index of 0.5 to 4 g/10 min; Olefin-based elastomers; A fluorine-based polymer resin containing polytetrafluoroethylene; And mixing the crystal nucleating agent to prepare a crosslinked olefin-based resin composition. And (b) melt-extruding and foaming the uncrosslinked olefin-based resin composition.

In the step (b), melt extrusion may be performed at 120 to 250°C.

In step (b), the fluorine-based polymer resin forms fibrils at 120 to 250° C., and the fibrils are entangled with the random polypropylene resin, the high-melting-tensile polypropylene resin, and the olefinic elastomer. It may be to form a (network) structure.

The fibrils may have an average diameter of 10 to 500 nm and an average length of 1 to 50 μm.

The foam according to the present invention for achieving the above another object comprises a foam of the crosslinked olefin-based resin composition according to any one of claims 1 to 5, and has a density of 0.04 to 0.1 g/cm ³ It is characterized by.

The foam may include a network structure.

The foam may include foam cells having an average diameter of 50 to 350 μm.

The foam may have a thickness of 0.5 to 2 mm.

The crosslinked olefin-based resin composition according to the present invention may improve processing characteristics and foaming characteristics of a resin composition, including a fluorine-based polymer resin, to increase melt viscosity.

The foam produced using the crosslinked olefin-based resin composition of the present invention can replace the foam manufactured using the existing cross-linked olefin-based resin, and provides effects such as simplification of the process, reduction in manufacturing cost, and productivity improvement. do.

1 is a flow chart showing a method for producing a foam according to the present invention.
2 is a cross-sectional view showing a foam according to the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Hereinafter, a crosslinked olefin resin composition according to a preferred embodiment of the present invention and a foam mill using the same will be described in detail with reference to the accompanying drawings.

The crosslinked olefin resin composition of the present invention can provide a crosslinked foam by forming a network structure of the resin composition by including polytetrafluoroethylene, which is a fluorine polymer resin, to increase melt viscosity.

The foam of the present invention may be applied to automobile interior materials, and more specifically, to a seat cover, door trim, and the like.

Non-crosslinked olefin resin composition

The crosslinked olefin-based resin composition of the present invention includes a random polypropylene resin, a high-melting-tensile polypropylene resin, an olefin-based elastomer, a fluorine-based polymer resin, and a crystal nucleating agent.

Polypropylene (PP) is produced by polymerizing propylene, and is a polymer composed of tertiary-carbon atoms. Random polypropylene (random polypropylene) is a polymer with a small amount of ethylene added during polymerization of the polypropylene, the arrangement of the monomers has a disordered form, and the polymer has a low stereoregularity. Random polypropylene has a characteristic that the impact strength and flexibility are improved and the transparency is improved, as compared to homo polypropylene, a polymer polymerized only with propylene, has many amorphous parts.

The random polypropylene resin of the present invention is a resin formed by copolymerizing propylene and ethylene, and is a form in which ethylene is bonded to propylene, which is a backbone. The random polypropylene resin may contain 10% by weight or less of ethylene with respect to 100% by weight of propylene and ethylene, and when the content of ethylene exceeds 10% by weight, transparency may decrease or elongation of the resin may decrease. .

The random polypropylene resin may have a weight average molecular weight of 2Х10 ⁵ ~10Х10 ⁵ , and in this range, a melt flow index (MFI) may be 4-10g/10min. When the weight average molecular weight of the random polypropylene resin is out of the above range, elongation of the uncrosslinked olefin resin composition may be reduced or compatibility between components may be reduced.

The weight average molecular weight refers to the average molecular weight obtained by calculating the average molecular weight of the polymer compound having a molecular weight distribution as a weight fraction. The melt index is an index indicating the flow of the melt, and the fluidity of the resin can be grasped from the melt index.

The high melt strength PP of the present invention (high melt strength PP) is higher than the general polypropylene melt viscosity, long-chain branch (LCB) structure increases the viscosity during stretching, strain hardening (strain hardening) ) Characteristic. Strain hardening refers to a phenomenon in which the hardness and strength of the material increase in the plastic zone.

That is, the high-melting-strength polypropylene resin increases the melt viscosity of the non-crosslinked olefin-based resin composition by a long chain branch structure to suppress the coalescence of the bubbles during molding, and prevents bubbles of the inert gas from escaping to the outside. do. Accordingly, the foam cell is uniformly formed and maintained in the foam.

The high melt strength polypropylene resin is preferably a melt index of 0.5 ~ 4g / 10min. If the melt index is less than 0.5g/10min, it may be difficult to satisfy the properties required in the foam due to the high viscosity. Conversely, when the melt index exceeds 4 g/10 min, the flowability of the high-melting-tensile polypropylene resin may be difficult to expect the melt tension effect while decreasing the viscosity.

It is preferable that the solid solution melt strength polypropylene resin is contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the random polypropylene resin. When the content of the high-solution melt tension polypropylene resin is less than 10 parts by weight, it may be difficult to obtain an effect of improving wear resistance and melt tension, and when it exceeds 50 parts by weight, processability may be deteriorated while the flowability of the non-crosslinked olefin resin composition decreases. Can.

The olefinic elastomer of the present invention is an elastomer having viscoelasticity, and can be produced by blending olefinic resins with various types of rubbers such as ethylene-propylene rubber. For example, ethylene-propylene rubber (EPR), ethylene-propylene-diene monomer (EPDM), and the like may be included, and it is preferable that it is an olefin-based elastomer showing elasticity and flexibility.

The olefin-based elastomer preferably has a melt index of 3 to 10 g/10 min, and if it is outside this range, there is a problem that the flowability of the non-crosslinked olefin-based resin composition decreases or the elasticity of the foam decreases.

In addition, the olefin-based elastomer may have a Shore hardness of 65 to 90A or an elongation of 500 to 1200%, but is not limited thereto.

It is preferable that the olefin-based elastomer is contained in an amount of 50 to 300 parts by weight based on 100 parts by weight of the random polypropylene resin. When the content of the olefin-based elastomer is less than 50 parts by weight, the flexibility of the foam decreases, and when it exceeds 300 parts by weight, the flexibility of the foam may be excellent, but mechanical properties and process stability are deteriorated, which is not preferable.

The fluorine-based polymer resin of the present invention is added to increase the melt viscosity of the uncrosslinked olefin-based resin composition, and may include polytetrafluoroethylene (PTFE).

The polytetrafluoroethylene may be prepared using a monomer having tetrafluoroethylene as a main component.

The polytetrafluoroethylene is present as a powder in the form of spherical particles, and then mixed and melt-extruded with random polypropylene, high-melting-tensile polypropylene, and the like. At this time, the polytetrafluoroethylene is transformed into a small fiber form by a shear stress at a high temperature of 120 ~ 250 ℃. Accordingly, the melt tension of the crosslinked olefin-based resin composition increases, and the fibrils form fibrosis together with other resins. Fibrosis means forming a entangled region in the shape of a net, and the network structure in which the random polypropylene resin, the high-melting-tensile polypropylene resin, the olefin-based elastomer and the small fibers are intertwined by such fiberization Is formed.

That is, the fluorine-based polymer resin containing the polytetrafluoroethylene forms small fibers through shear stress at 120 to 250°C, and the small fibers form a network structure to melt the crosslinked olefin-based resin composition. Increase viscosity. The shear stress means that the force acting in a direction parallel to the surface is divided by the acting area.

The polytetrafluoroethylene is preferably included in an amount of 0.3 to 3 parts by weight based on 100 parts by weight of the random polypropylene resin. When the content is less than 0.3 parts by weight, the melt viscosity of the non-crosslinked olefin-based resin composition may be too low to control the size of the foamed cell, and when the content exceeds 3 parts by weight, melting of the cross-linked olefin-based resin composition Since the viscosity is considerably high, the formation of the foam cell is not smooth, and thus the physical properties of the foam may be deteriorated.

Since the polytetrafluoroethylene is included in the resin composition, physical properties of the final product foam, in particular, elasticity and surface glossiness may be affected.

The crystal nucleating agent of the present invention can improve mechanical properties such as hardness, elongation, and foam magnification of the produced foam by contributing to the foam molding process.

The crystal nucleating agent of the present invention may include talc, and the crystal nucleating agent may further include an organic nucleating agent such as a rosin-based nucleating agent.

It is preferable that the crystal nucleating agent is contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the random polypropylene resin. When the content of the crystal nucleating agent is less than 0.1 parts by weight, foaming may not be properly performed, and thus it may be difficult to form a foam cell having a uniform diameter. Conversely, when it exceeds 2 parts by weight, it is difficult to disperse the crystal nucleating agent, and a foam cell having a small diameter is formed, and the effect of improving the mechanical properties of the foam is insufficient.

The crosslinked olefin resin composition of the present invention may or may not include a blowing agent. In the case of including a blowing agent, a gas blowing agent can be used, and for example, an inorganic gas-based blowing agent such as nitrogen, argon, or air can be used.

The crosslinked olefin-based resin composition of the present invention may further include additives such as a heat stabilizer and an antibacterial agent, in addition to the suggested components, but is not limited thereto.

As described above, the non-crosslinked olefin-based resin composition of the present invention may include a fluorine-based polymer resin, thereby increasing the melt viscosity of the resin composition as the network structure is formed.

In the present invention, the melt viscosity of the composition may be increased by about 1.5 to 3 times compared to the melt viscosity of the existing olefin-based resin composition.

Method for manufacturing foam

1 is a flow chart showing a method for producing a foam according to the present invention.

Referring to Figure 1, the method for producing a foam according to the present invention comprises a crosslinking olefin-based resin composition production step (S110) and melt extrusion to the foaming step (S120).

Manufacturing step of non-crosslinked olefin resin composition (S110)

First, a crosslinked olefin-based resin composition is prepared.

The crosslinked olefin-based resin composition may be as described above.

Foaming step by melt extrusion (S120)

Next, the crosslinked olefin resin composition is injected into an extruder and melt-extruded to foam.

The temperature of the extruder is preferably 120 ~ 250 ℃, the composition can be uniformly dispersed and mixed in this temperature range is melt-extruded.

When melt extrusion is performed at a temperature of less than 120°C, the crosslinked olefin-based resin composition may be difficult to uniformly disperse and mix, and when melt extrusion is performed at a temperature exceeding 250°C, the melt viscosity of the resin composition is It can be difficult to form normal foam cells, such as low closed cells.

While melt extrusion is performed at 120 to 250° C., the fluorine-based polymer resin forms fibrils through high temperature and shear stress, and the fibrils form a network structure with the resin contained in the non-crosslinked olefin resin composition. And, it is possible to manufacture a foam having a network structure.

The fibrils may have an average diameter of 10 to 500 nm and an average length of 1 to 50 μm. When the diameter and length of the small fibers are out of this range, it may be difficult to form fiberization with other polypropylene resins, and thus it may be difficult to form a network structure.

After the melt extrusion, the temperature may be changed to room temperature ±5°C to maintain the shape of the foam, but is not limited thereto.

2 is a cross-sectional view showing a foam according to the present invention.

The foam 10 according to the present invention is a non-crosslinked foam, and forms a network structure 20 by a viscosity modifier containing polytetrafluoroethylene, so that a foam cell (cell, not shown) is preserved for a long time.

The foam 10 is formed by foaming a non-crosslinked olefin-based resin composition, and may have a density of 0.04 to 0.1 g/cm ³ . When the density is outside the above range, it is difficult to expect a light weight effect and the physical properties of the foam may be deteriorated.

As described above, the foam 10 forms a network structure in which the resin and fibrils are entangled, so that the formation of a foam cell during the extrusion process is well maintained.

The foam cell may be classified into a closed cell in which all the walls of the pores are closed, or a continuous cell in which some of the walls of the pores are open.

Continuous pores (opened cell) may be formed by the gas generated in the process of foaming the composition to form a bubble, the bubble continues to grow and then rupture. In addition, as the bubble grows, the bubble wall surface between neighboring bubbles and those separating them becomes thinner and may be formed by bursting of bubbles.

The foam of the present invention may include 80 to 100% of closed pores, and may include a foam cell that is 20% or less of the remaining pores.

For example, closed pores may include 80-90%, continuous pores may include 10-20%, or closed pores may consist of 100%. When the content of the closed pores, that is, the independent pores is less than 80%, since it is difficult to exhibit excellent strength and light weight of the foam, the closed pores are preferably 80% or more.

The foam of the present invention preferably includes a foam cell having an average diameter of 50 to 350 μm, which may mean an average diameter of closed pores. When the average diameter of the foamed cell is less than 50 μm, the diameter of the cell becomes too small, resulting in problems of reduced flexibility and physical properties of the foamed body. Conversely, when the diameter exceeds 350 μm, the cells may be formed into continuous pores as the cells burst or the wall becomes thinner.

As shown in Fig. 2, the foam 10 of the present invention may have a thickness (d) of 0.5 to 2 mm, and if it is outside this range, it is difficult to thermally bond with the surface fabric layer to improve the moldability as a vehicle interior material. There is a problem.

As described above, the foam of the present invention is a non-crosslinked foam, and can be applied to automobile interior materials, and more specifically, to a seat cover, door trim, and the like.

The specific examples of the non-crosslinked olefin resin composition and the foam using the same and a method of manufacturing the same are as follows.

1. Preparation and results of foam

Example

With respect to 100 parts by weight of a random polypropylene resin containing 10% by weight of ethylene and 90% by weight of propylene, 20 parts by weight of a high melt strength polypropylene resin having a melt index of 2g/10min and an olefinic elastomer having a melt index of 6g/10min (Vistamaxx of ExxonMobil Chemical) 100 parts by weight, 3 parts by weight of polytetrafluoroethylene and 1 part by weight of talc as a crystal nucleating agent were mixed to prepare a resin composition.

In the process of melting and extruding the resin composition at 170° C. to form a fibrous fiber having a diameter of 100 nm and a length of 30 μm, the fibrous fiber forms a network structure entangled with the resin and elastomer contained in the composition. Did.

As a result, a foam cell having a diameter of 300 µm, a thickness of 1.5 mm, and a density of 0.06 g/cm ³ was prepared.

Comparative example

With respect to 100 parts by weight of a random polypropylene resin containing 10% by weight of ethylene and 90% by weight of propylene, 20 parts by weight of a high melt strength polypropylene resin having a melt index of 2g/10min and an olefinic elastomer having a melt index of 15g/10min (Vistamaxx of ExxonMobil Chemical) 100 parts by weight and 1 part by weight of talc as a crystal nucleating agent were mixed to prepare a resin composition.

The resin composition was melt-extruded at 170° C. to foam to produce a foam cell having a diameter of 700 μm, a thickness of 1.5 mm, and a density of 0.4 g/cm ³ .

The foam of the embodiment includes polytetrafluoroethylene, thereby forming small fibers in the process of extrusion and foaming to form a network structure, and the shape of the foam cell is maintained by the intertwined network structure to maintain a density of 0.06 g/cm ³ It was shown.

On the other hand, the foam of the comparative example did not contain polytetrafluoroethylene, and the melt index of the olefin-based elastomer was outside the scope of the claims of the present invention, and thus, the result was larger than the foam cell diameter of the examples, and the density was high.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and may be manufactured in various different forms, and having ordinary knowledge in the art to which the present invention pertains. It will be understood that a person can be practiced in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: foam
20: network structure
d: foam thickness

Claims (14)

A random polypropylene resin containing 10% by weight or less of ethylene to 100% by weight of propylene and ethylene;
A high melt strength polypropylene resin having a melt index of 0.5 to 4 g/10 min;
Olefin-based elastomers;
Fluorine-based polymer resins; And
Crystal nucleating agent;
The fluorine-based polymer resin forms a small fiber at 120 ~ 250 ℃,
The fibril is a non-crosslinked olefin resin composition characterized by forming a network structure intertwined with a random polypropylene resin, a high melt strength polypropylene resin, and an olefin elastomer through fiberization.
According to claim 1,
The fluorine-based polymer resin is a cross-linked olefin-based resin composition comprising a polytetrafluoroethylene.
According to claim 1,
The crosslinked olefin-based resin composition is
It contains 10 to 50 parts by weight of high melt strength polypropylene resin, 50 to 300 parts by weight of olefin-based elastomer, 0.3 to 3 parts by weight of fluorine-based polymer resin, and 0.1 to 2 parts by weight of crystal nucleating agent with respect to 100 parts by weight of random polypropylene resin. A crosslinked olefin-based resin composition, characterized in that.
According to claim 1,
The olefin-based elastomer is a crosslinked olefin-based resin composition, characterized in that the melt index is 3 ~ 10g / 10min.
delete According to claim 1,
The crystal nucleating agent is a crosslinked olefin-based resin composition, characterized in that it comprises a talc (talc).
(a) random polypropylene resin containing 10% by weight or less of ethylene to 100% by weight of propylene and ethylene; A high melt strength polypropylene resin having a melt index of 0.5 to 4 g/10 min; Olefin-based elastomers; A fluorine-based polymer resin containing polytetrafluoroethylene in powder form; And mixing the crystal nucleating agent to prepare a crosslinked olefin-based resin composition. And
(b) the step of melting and extruding the crosslinked olefin-based resin composition at 120 to 250°C to foam;
In step (b),
The fluorine-based polymer resin forms fibrils, and the fibrils are foams characterized by forming a network structure intertwined with a random polypropylene resin, a high-melting-tensile polypropylene resin, and an olefin-based elastomer. Method of manufacture.
delete delete The method of claim 7,
The small fiber has an average diameter of 10 ~ 500nm, the average length of 1 ~ 50㎛ foam manufacturing method characterized in that.
Claims 1 to 4, comprising a foam of the crosslinked olefin-based resin composition according to any one of claims 6,
The density is 0.04~0.1g/cm ³ ,
A foam comprising a network structure.
delete The method of claim 11,
The foam is a foam, characterized in that it comprises a foam cell having an average diameter of 50 ~ 350㎛.
The method of claim 11,
The foam is a foam, characterized in that the thickness is 0.5 ~ 2mm.

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