KR20220070972A - Preparing method of polypropylene resin composition with excellent foaming performance and article foamed with the same - Google Patents

Abstract

Disclosed are a method for preparing a polypropylene resin composition for forming with more improved foaming properties in a polypropylene for foaming which is prepared by irradiating an electron beam to general linear polypropylene, and a method for preparing polypropylene foam using the same. The present invention provides a method for preparing a polypropylene resin composition for foaming and a method for preparing a polypropylene foam using the same, wherein the method comprises the steps of: obtaining a mixture by mixing 0.01 to 3 parts by weight of a crosslinking agent with respect to 100 parts by weight of polypropylene; and irradiating the mixture with an electron beam in an inert gas atmosphere in which active oxygen is used in an amount of 0.1 volume % or less.

Description

A polypropylene resin composition for foaming and a method for producing a polypropylene foam having excellent foaming performance {Preparing method of polypropylene resin composition with excellent foaming performance and article foamed with the same}

The present invention relates to a polypropylene resin composition for foaming and a method for producing a polypropylene foam, and more particularly, to a polypropylene resin composition for foaming excellent in foaming performance and a method for producing a polypropylene foam.

Polypropylene has been used in various applications such as food containers, packaging materials, automobile parts, and industrial parts due to its excellent properties, moldability, chemical resistance, and low price. However, general polypropylene has a low melt strength by forming a linear structure, and does not exhibit a shear thickening behavior in which the viscosity increases according to the shear rate. Due to insufficient melt strength and shear thickening behavior, the cell wall becomes thinner in the foaming process, and it is easy to form a fused cell due to the opening of the cell, which causes a problem in that the physical properties of the foaming container are deteriorated.

As a way to solve this problem, a method for producing polypropylene with improved melt strength has been developed, but most have been carried out as a method of reforming linear polypropylene by introducing long-chain branching through reaction extrusion after addition of organic peroxide. This method cannot directly control the degree of introduction of long-chain branches according to the organic peroxide reaction, and the physical properties of the final polymer are affected by the type and content of the organic peroxide.

Another method for producing a polypropylene foam with improved foaming performance is to use a method for improving melt strength through electron beam irradiation. When the linear polypropylene is irradiated with an electron beam, free radicals are generated, and the chains that are broken due to the radicals are introduced into the branches and the melt strength is improved by entanglement between the chains. In this method, the melt strength can be improved by simply exposing the polymerized linear polypropylene to an electron beam accelerator for a short period of time. In order to cause branching introduction more than chain breakage, high-energy electron beam irradiation is required.

Korean Patent No. 10-0311290 is a method of manufacturing a propylene polymer material with high melt strength by irradiating electron beams on polypropylene. After polymerization of linear polypropylene, electron beams are irradiated in a nitrogen atmosphere in a spinning chamber and pelletized to form non-linear propylene The polymer was prepared. As a result of the foaming evaluation of the manufactured polymer, it showed a good foaming ratio of up to 8 times, but there was a problem that Chlorofluorocarbon (CFC) gas, an ozone depleting substance currently banned internationally, was used as a foaming agent at a high content of 8%. have.

Japanese Patent Application Laid-Open No. 2011-510128 uses a photoinitiator and triallyl cyanurate-based material in an olefin polymer and improves melt strength and melt strength by UV irradiation, but a photoinitiator is essential to introduce free radicals before UV irradiation. It has to be added, and although the melt strength is improved, the actual expansion ratio is only 2 times, so there is a problem that the foaming performance is low.

The present invention relates to a method for producing a polypropylene resin composition for foaming having more improved foaming properties in a polypropylene for foaming produced by irradiating an electron beam to a general linear polypropylene, and a polypropylene resin composition for foaming and polypropylene using the same An object of the present invention is to provide a method for manufacturing a foam.

As a first aspect for solving the above problems, the present invention comprises the steps of mixing 0.01 to 3 parts by weight of a crosslinking agent with respect to 100 parts by weight of polypropylene to obtain a mixture; and irradiating the mixture with an electron beam in an inert gas atmosphere containing 0.1% by volume or less of active oxygen by volume.

In addition, the polypropylene is at least one selected from the group consisting of a propylene homopolymer, a propylene random copolymer, and an impact polypropylene having a melt index (230° C., 2.16 kg load) of 0.1 to 50 g/10 min, and the crosslinking agent is a tri Allyl isocyanurate, triallyl cyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl trimesate trimesate), triallyl phosphate (Triallyl phosphate), pentaerythritol triacrylate (Pentaerythritol triacrylate) and divinylbenzene (Divinylbenzene) provides a method for producing a polypropylene resin composition for foaming, characterized in that at least one selected from the group consisting of do.

In addition, the electron beam irradiation dose provides a method for producing a polypropylene resin composition for foaming, characterized in that 1 to 70 kGy.

In order to solve the another problem, the present invention is prepared according to the above method, and the elongational viscosity measured according to the following method is 1,000 to 5,000 kPa·s, and the polypropylene for foaming having a gel content of 0.1 to 5% by weight A resin composition is provided.

[Method for measuring elongational viscosity]

Specimens with a width of 20 mm, a length of 10 mm, and a thickness of 7 mm were fixed on the sample holder using an advanced rheometric expansion system (ARES), It is measured as the resistance value taken when the specimen rotates around the axis at speed, and the maximum value of the tension that changes according to the rotational distance (elongation rate) of the specimen is referred to as the extensional viscosity.

[Method for measuring gel content]

The dried mixture is ground in xylene according to ASTM D2765 standard, dissolved at the boiling point for 12 hours, and then the insoluble content is measured.

As a second aspect for solving the above problem, the present invention also comprises the steps of mixing 0.01 to 3 parts by weight of triallyl isocyanurate as a crosslinking agent with respect to 100 parts by weight of polypropylene to obtain a mixture; and irradiating the mixture with an electron beam; provides a method for producing a polypropylene resin composition for foaming comprising.

In order to solve the another problem, the present invention provides a method for producing a polypropylene foam comprising the step of adding 0.01 to 3 parts by weight of a nucleating agent to 100 parts by weight of the resin composition, and adding a foaming agent to foam.

In addition, the nucleating agent is talc, calcium carbonate, bentonite, zeolite, ammonium bicarbonate, sodium bicarbonate, sodium borohydride, Azodicarbonamide (ADCA), Dinitrosopentamethylenetetramine (DPT), Benzenesulfonyl hydrazide (BSH), Toluenesulfonyl hydrazide (TSH) and toluenesulfonyl hydrazide (TSH) It provides a method for producing a polypropylene foam, characterized in that at least one selected from the group consisting of sulfonyl semicarbazide (Toluenesulfonyl semicarbazide, PTSS).

In addition, the blowing agent is selected from the group consisting of carbon dioxide (CO ₂ ), nitrogen (N ₂ ), hydrofluorocarbon (HFC), chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), isobutane and cyclopentane It provides a method for producing a polypropylene foam, characterized in that at least one type.

The present invention prepares a polypropylene resin composition through electron beam irradiation after mixing and melt-extruding a crosslinking agent into polypropylene, but performing electron beam irradiation after removing active oxygen, and further crosslinking by introducing long-chain branches during electron beam irradiation using a specific crosslinking agent It is possible to provide a method for preparing a polypropylene resin composition for foaming in which the effect is maximized and the melt strength is improved by controlling the content of the crosslinking agent and the amount of electron beam absorption.

In addition, when foaming using a polypropylene resin composition, a nucleating agent capable of maximizing cell nucleation is added and a specific foaming agent is added to facilitate cell formation and growth during foaming, thereby improving the expansion ratio. can provide

In addition, in the prior art, a high content of Freon gas, a prohibited substance, was added to improve the foaming ratio, or a crosslinking agent, photoinitiator, auxiliary additive, etc. were additionally added to improve the melt strength, but the improvement in the foaming ratio was insignificant. According to the invention, without using a prohibited substance such as Freon gas, by injecting a small amount of carbon dioxide as a foaming agent and irradiating an electron beam under active oxygen removal, the crosslinking performance can be maximized, thereby greatly improving the foaming ratio compared to the prior art.

Hereinafter, preferred embodiments of the present invention will be described in detail. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

As a first aspect, the present invention comprises the steps of mixing and melt-extruding 0.01 to 3 parts by weight of a crosslinking agent with respect to 100 parts by weight of polypropylene to obtain a mixture; And irradiating the mixture with an electron beam in an inert gas atmosphere having an active oxygen content of 0.1% by volume or less; Mixing and melt-extruding 0.01 to 3 parts by weight of Triallyl isocyanurate to obtain a mixture; and irradiating the mixture with an electron beam; discloses a method for producing a polypropylene resin composition for foaming comprising.

The present invention is to provide a method for producing a polypropylene resin composition for foaming used in the production of foams such as low-density polypropylene containers having excellent foaming properties by irradiating electron beams on general linear polypropylene, and a method for producing a polypropylene foam using the same. , polypropylene foam is commercially used in various forms such as automobile cushions, insulation materials, lightweight buoyancy materials, and foam mats. The present invention provides a method for preparing a polypropylene resin composition for foaming that can be foamed at a high magnification applicable to these uses.

Although the technology for producing polypropylene with high melt strength by irradiating electron beams is already known, polypropylene with too high melt strength has a limitation in cell growth during foaming, so foaming performance is rather deteriorated. In the present invention, polypropylene in which a specific crosslinking agent such as triallyl isocyanurate (TAIC) is mixed with linear polypropylene is irradiated with electron beams in an environment in which active oxygen is removed. Polypropylene having melt strength suitable for foaming It can be prepared as a resin composition, and by adding a specific nucleating agent to the produced polypropylene resin composition to improve the expansion ratio, low-density foams such as foam containers can be molded.

In the present invention, the polypropylene is not particularly limited as long as it is a resin for improving melt strength through electron beam irradiation, but propylene homopolymer, propylene random copolymer, or impact polypropylene may be used. In this case, the comonomer used for preparing the propylene copolymer is preferably an α-olefin having 2 to 10 carbon atoms other than propylene, and the content of the comonomer may be 30% by weight or less, preferably 1 to 10% by weight. These polypropylenes can be used as those produced by conventionally known processes.

At this time, the polypropylene may have a melt index (230° C., 2.16 kg load) of 0.1 to 50 g/10 min, preferably 1 to 10 g, in consideration of moldability and improvement of melt strength due to low-dose electron beam irradiation. /10 min. If the melt index is less than 0.1 g/10min, non-melting of the pellets may occur due to an increase in the bonding of the generated radicals, and the defect rate may increase due to the low flowability, such as non-molding. In addition, if the melt index exceeds 50 g/10 min, molding may be difficult due to insufficient magnification during foaming or high flowability during container molding due to a relatively low molecular weight.

In the present invention, the crosslinking agent includes triallyl isocyanurate, triallyl cyanurate, trimethylolpropane trimethacrylate, and trimethylolpropane triacrylate. , triallyl trimesate, triallyl phosphate, pentaerythritol triacrylate, divinylbenzene, etc. may be used, and crosslinking by introduction of long-chain branches during electron beam irradiation It is preferable to select triallyl isocyanurate (TAIC) having the structure of the following formula 1 in consideration of maximizing the effect and realizing the maximized foaming performance by controlling the amount of crosslinking agent and electron beam absorption.

[Formula 1]

The crosslinking agent may be mixed in an amount of 0.01 to 3 parts by weight, preferably 0.1 to 2 parts by weight, more preferably 0.5 to 1.5 parts by weight based on 100 parts by weight of the polypropylene. When the content of the crosslinking agent is less than 0.01 parts by weight, it is difficult to expect a satisfactory crosslinking effect, and when it exceeds 3 parts by weight, the crosslinking effect of polypropylene increases and many long chain branches can be introduced. Thus, the foaming performance is rather reduced.

In the present invention, the polypropylene and the crosslinking agent may be mixed according to a conventional method known in the art. For example, it can be prepared into pellets by melt-extruding the components in a mixer in the required amount and then mixing them with an extruder having an extrusion temperature of 190 to 230° C. and a screw rotation speed of 95 to 100 rpm.

In the present invention, electron beam irradiation is performed on the mixture of polypropylene and crosslinking agent prepared above in order to generate free radicals in polypropylene and to improve melt strength due to the occurrence of entanglement between chains by introducing into branches the broken chains due to radicals. The free radicals generated by performing electron beam irradiation in an oxygen-removed atmosphere are maintained so that the crosslinking effect of the crosslinking agent is further maximized, thereby realizing more improved foaming performance than the conventional technology in which a crosslinking agent is added. In this case, the removal of active oxygen may be performed, for example, by purging the prepared mixture of polypropylene and a crosslinking agent with an inert gas such as nitrogen in an airtight container, and there is no particular limitation on the method.

In the present invention, electron beam irradiation may be performed using, for example, an electron beam accelerator having an irradiation amount of 10 MeV. In the present invention, even with low-dose electron beam irradiation to have an absorption of 1 to 70 kGy, preferably 10 to 60 kGy, and more preferably 20 to 50 kGy, chain entanglement sufficient to improve the desired melt strength is possible. If the irradiation dose is less than 1 kGy, it may be difficult to impart high melt strength due to the small number of generated radicals. have.

The polypropylene resin composition for foaming according to the present invention may further include one or more conventional additives known in the art as other additives, for example, an antioxidant, a neutralizing agent, a heat-resistant stabilizer, and the like. At this time, the content of each of these additives may be used in the range of 0.01 to 1 part by weight based on 100 parts by weight of the polypropylene resin composition for foaming of the present invention, but is not particularly limited thereto.

The polypropylene resin composition for foaming according to the present invention above exhibits melt strength properties suitable for foam molding, specifically, has an elongational viscosity of 1,000 to 5,000 kPa s measured according to the following method, and a gel content of 0.1 to 5% by weight. and preferably have an elongational viscosity of 1,500 to 3,000 kPa·s, and a gel content of 0.5 to 3 wt%.

[Method for measuring elongational viscosity]

Specimens with a width of 20 mm, a length of 10 mm, and a thickness of 7 mm were fixed on the sample holder using an advanced rheometric expansion system (ARES), It is measured as the resistance value taken when the specimen rotates around the axis at speed, and the maximum value of the tension that changes according to the rotational distance (elongation rate) of the specimen is referred to as the extensional viscosity.

[Method for measuring gel content]

The dried mixture is ground in xylene according to ASTM D2765 standard, dissolved at the boiling point for 12 hours, and then the insoluble content is measured.

The present invention discloses a method for producing a foam using the polypropylene resin composition for foaming prepared above, the method comprising adding 0.01 to 3 parts by weight of a nucleating agent to the resin composition and foaming by introducing a foaming agent do.

The nucleating agent serves to maximize cell nucleation when foaming using the polypropylene resin composition, and by adding a foaming agent together with the addition of the nucleating agent, cell formation and growth are facilitated during foaming, so that the expansion ratio is improved. That is, the nucleating agent is dispersed in the melted polypropylene and acts as a nucleating agent for the cells formed during foaming to form cells, thereby increasing the cell density after foaming and improving the expansion ratio. Due to the polypropylene resin composition containing a preferred nucleating agent described later in the present invention, the cell density can be increased to increase the number of cells during foaming, and as described above, the polypropylene resin composition containing the crosslinking agent is irradiated with electron beams. By appropriately improving the melt strength, the melt strength required for each cell growth is secured during foaming to enable cell growth without cell fusion, thereby making it possible to manufacture a foam with improved foaming performance.

The nucleating agent includes, for example, talc, calcium carbonate, bentonite, zeolite, ammonium bicarbonate, sodium bicarbonate, sodium borohydrate. ), azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), benzenesulfonyl hydrazide (BSH), toluenesulfonyl hydrazide (TSH) And toluenesulfonyl semicarbazide (Toluenesulfonyl semicarbazide, PTSS) may be used at least one member selected from the group consisting of, dispersibility in the polypropylene resin composition and cell density during foaming and foaming performance through cell growth in consideration It is preferred to use talc or sodium bicarbonate.

As the blowing agent used in the foaming process in the present invention, for example, carbon dioxide (CO ₂ ), nitrogen (N ₂ ), hydrofluorocarbon (HFC), chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), iso butane, cyclopentane, and the like, and carbon dioxide or nitrogen may be preferably used in consideration of the environmental aspect, and as described above, through the use of a specific crosslinking agent and electron beam irradiation under active oxygen removal, Freon gas, etc. is prohibited It is possible to greatly improve the expansion ratio compared to the prior art by maximizing the crosslinking performance while adding a small amount of carbon dioxide without using a substance.

In the past, in order to improve the foaming ratio, it was possible to increase the melt strength by injecting a high content of Freon gas as a foaming agent or by adding a triallyl cyanurate-based material and a photoinitiator to UV irradiation. When triallyl isocyanurate is added as a specific crosslinking agent in the present invention, the decomposition reaction between the polypropylene chain and triallyl isocyanurate is suppressed by irradiating electron beams in an environment in which active oxygen is removed, thereby further enhancing the crosslinking effect. . In this case, the effect of the crosslinking agent can be expressed without the use of additional additives such as the existing photoinitiator, thereby eliminating the need for high-energy electron beam irradiation. In addition, by injecting a small amount of carbon dioxide or the like without using a toxic gas as a foaming agent, the density is greatly reduced, so that it is possible to manufacture a foam having an improved expansion ratio.

In the present invention, the foaming process is not particularly limited and a conventional method known in the art may be used. For example, a nucleating agent is dry blended into a pellet of polypropylene irradiated with electron beam and a crosslinking agent, and a foaming agent such as carbon dioxide is added, the foaming temperature is 160 to 200 ° C, the screw rotation speed 100 to 200 rpm, a gear pump ( gear pump) The foaming process may be performed under the conditions of a rotation speed of 10 to 30 rpm.

The polypropylene foam produced according to the present invention can be applied to food containers such as lunch boxes, cup noodle containers, and meat trays, thereby reducing the amount of plastic used, and polystyrene (PS) containers and polyethylene terephthalate (PET) used in the past It has the advantage of being able to cook in a microwave compared to a container. In addition, when used as a packaging material, it is possible to prevent impact of the product in electronic products, etc.

Hereinafter, specific examples according to the present invention will be described.

Example 1

To 100 parts by weight of the propylene homopolymer, 0.7 parts by weight of triallyl isocyanurate as a crosslinking agent was melt-kneaded with a single screw extruder at an extrusion temperature of 190 to 230° C. and a screw rotation speed of 95 to 100 rpm to prepare a pellet mixture. The prepared pellets were placed in a bag and cross-linked at an electron beam absorption of 20 kGy using an electron beam accelerator with a dose of 10 MeV to prepare a polypropylene resin composition.

Examples 2 to 4, Comparative Examples 1 to 8

A polypropylene resin composition was prepared in the same manner as in Example 1, except that the content of the crosslinking agent and the amount of electron beam absorption in Example 1 were adjusted as shown in Table 1.

Example 5

To 100 parts by weight of the propylene homopolymer, 0.7 parts by weight of triallyl isocyanurate as a crosslinking agent was melt-kneaded with a single screw extruder to prepare a pellet mixture. The prepared pellets were placed in a bag and purged with nitrogen to remove active oxygen at a concentration of 0.1% by volume or less. A polypropylene resin composition was prepared by crosslinking in an environment in which active oxygen was removed at an electron beam absorption of 20 kGy.

Example 6

According to Example 1, 0.3 parts by weight of talc (nucleating agent 1) was added as a nucleating agent to the pellets irradiated with electron beam according to Example 1 and dry blended, carbon dioxide was added as a foaming agent, a foaming temperature of 160 to 200 ° C, and a screw rotation speed of 150 rpm , a polypropylene foam was prepared by foaming under the conditions of a gear pump rotation speed of 20 rpm.

Examples 7 to 9, Comparative Examples 9 to 12

A polypropylene foam was prepared in the same manner as in Example 6, except that the polypropylene pellets used in Example 6, the type and content of the nucleating agent were adjusted as shown in Table 2 below. In Table 2, sodium hydrogen carbonate was used as 'nucleating agent 2'.

test example

For the polypropylene pellets and foams prepared according to the Examples and Comparative Examples, elongational viscosity, gel content, density, and expansion ratio were measured by the following method, and the results are shown in Tables 1 and 2 below.

[Method for measuring elongational viscosity]

Specimens with a width of 20 mm, a length of 10 mm, and a thickness of 7 mm were fixed on the sample holder using an advanced rheometric expansion system (ARES), It was measured as the resistance value taken when the specimen rotates around the axis at speed, and the maximum value among the tensions that change according to the rotational distance (elongation rate) of the specimen was used as the extensional viscosity.

[Method for measuring gel content]

The dried mixture was pulverized according to ASTM D2765 standard, put in xylene, dissolved at the boiling point for 12 hours, and then the insoluble content was measured.

[Method for measuring density and expansion ratio]

Density was measured by an underwater displacement method according to ASTM D792 standard. The foam is cut and a weight is suspended in water to obtain the volume, and the mass of the foam is measured using an upper plate scale to calculate the density, and the measured density is divided by 0.9 g/cm 3, the known density of polypropylene, to increase the expansion ratio. was calculated.

division Example 6 Example 7 Example 8 Example 9 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 polypropylene pellets Example 1 Example 1 Example 5 Example 5 Comparative Example 5 Comparative Example 5 Comparative Example 5 Example 1 nuclear number 1
(parts by weight) 0.3 - 0.3 - - 0.3 - - nuclear second
(parts by weight) - 0.3 - 0.3 - - 0.3 - Density (g/cm3) 0.30 0.27 0.22 0.21 0.78 0.62 0.59 0.51 Firing ratio (x) 3.0 3.3 4.1 4.3 1.2 1.5 1.5 1.8

Referring to Tables 1 and 2, when triallyl isocyanurate is mixed with polypropylene in a specific content range as a crosslinking agent in accordance with the present invention and then electron beam irradiation is performed (Examples 1 to 4), elongational viscosity is significantly improved Therefore, it can be confirmed that the melt strength of polypropylene is greatly improved due to the addition of a specific crosslinking agent and electron beam irradiation. In addition, as a result of measuring the gel content, it can be confirmed that the crosslinking effect was exhibited by introducing long-chain branches into polypropylene at a level of 0.9 to 1.8 wt%.

At this time, as the amount of electron beam absorption increases, the crosslinking effect increases, increasing the elongational viscosity and the gel content (comparison of Examples 1 and 2, comparison of Examples 3 and 4), and as the content of the crosslinking agent increases, the polypropylene has long-chain branching As the introduction progressed more, it can be seen that the elongational viscosity and the gel content further increased (Comparison of Examples 1 and 3, Comparison of Examples 2 and 4).

In contrast, when the crosslinking agent in the present invention was not added (Comparative Example 2) or electron beam was not irradiated (Comparative Example 5), the elongational viscosity was significantly lowered.

In addition, referring to the results of Comparative Examples 2 to 4, although the electron beam was irradiated, the crosslinking agent was not included, so the crosslinking effect by electron beam irradiation did not appear at all. It can be seen that a decrease

In addition, referring to the results of Comparative Examples 5 and 7, although the crosslinking agent in the present invention was added in a specific content range, the effect of introducing a long chain branch by the crosslinking agent did not appear because the electron beam was not irradiated, and when the crosslinking agent was not added (Comparative Example There was no difference between 1) and elongational viscosity and gel content.

In addition, when the crosslinking agent in the present invention is added in a specific content range and the electron beam absorption amount is 80 kGy (Comparative Examples 6 and 8), the electron beam absorption amount increases and the crosslinking effect is excessive, which results in a significant increase in the gel content And, the elastic effect of the sample was maximized, so it was impossible to measure the elongational viscosity.

On the other hand, when the electron beam irradiation according to the present invention is carried out in an environment in which active oxygen is removed (Example 5), it can be confirmed that the elongational viscosity and the gel content are further increased.

Next, when foaming is performed by adding a specific nucleating agent in the present invention (Examples 6 and 7), the foaming ratio shows excellent foaming properties at a level of 3 times or more, and electron beam irradiation is performed in an environment in which active oxygen is removed. When foaming using the prepared pellets (Examples 8 and 9), it can be seen that the foaming property is further improved to a level of 4 or more times the foaming ratio.

In contrast, when foaming is performed without adding a nucleating agent (Comparative Examples 9 and 12) or when foaming is performed using pellets prepared without irradiating an electron beam even with the addition of a nucleating agent (Comparative Examples 10 and 11) It can be seen that the properties are significantly reduced.

The preferred embodiment of the present invention has been described in detail above. The description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains will understand that other specific forms can be easily modified without changing the technical spirit or essential features of the present invention.

Accordingly, the scope of the present invention is indicated by the claims to be described later rather than the above detailed description, and all changes or modifications derived from the meaning, scope, and equivalent concept of the claims are included in the scope of the present invention. should be interpreted

Claims (8)

mixing 0.01 to 3 parts by weight of a crosslinking agent with respect to 100 parts by weight of polypropylene to obtain a mixture; and
irradiating the mixture with an electron beam in an inert gas atmosphere in which active oxygen is 0.1% by volume or less;
A method for producing a polypropylene resin composition for foaming comprising a. According to claim 1,
The polypropylene is at least one selected from the group consisting of a propylene homopolymer, a propylene random copolymer, and an impact polypropylene having a melt index (230° C., 2.16 kg load) of 0.1 to 50 g/10 min,
The crosslinking agent is triallyl isocyanurate, triallyl cyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl tri Polypropylene resin composition for foaming, characterized in that at least one selected from the group consisting of mesate (Triallyl trimesate), triallyl phosphate (Triallyl phosphate), pentaerythritol triacrylate (Pentaerythritol triacrylate) and divinylbenzene (Divinylbenzene) manufacturing method. mixing 0.01 to 3 parts by weight of triallyl isocyanurate as a crosslinking agent with respect to 100 parts by weight of polypropylene to obtain a mixture; and
irradiating the mixture with electron beams;
A method for producing a polypropylene resin composition for foaming comprising a. According to claim 1,
The method for producing a polypropylene resin composition for foaming, characterized in that the electron beam irradiation dose is 1 to 70 kGy. A polypropylene resin composition for foaming prepared according to any one of claims 1 to 4, having an elongational viscosity of 1,000 to 5,000 kPa·s, and a gel content of 0.1 to 5% by weight, measured according to the following method:
[Method for measuring elongational viscosity]
Specimens with a width of 20 mm, a length of 10 mm, and a thickness of 7 mm were fixed to the sample holder using an advanced rheometric expansion system (ARES), It is measured as the resistance value when the specimen rotates around the axis at speed, and the maximum value of the tension that changes according to the rotational distance (elongation rate) of the specimen is referred to as the extensional viscosity.
[Method for measuring gel content]
In accordance with ASTM D2765, the dried mixture is ground in xylene, dissolved at the boiling point for 12 hours, and the insoluble content is measured. A polypropylene foam manufacturing method comprising a; adding 0.01 to 3 parts by weight of a nucleating agent to 100 parts by weight of the resin composition of claim 5, and foaming by adding a foaming agent. 7. The method of claim 6,
The nucleating agent is talc, calcium carbonate, bentonite, zeolite, ammonium bicarbonate, sodium bicarbonate, sodium borohydride, azo Azodicarbonamide (ADCA), Dinitrosopentamethylenetetramine (DPT), Benzenesulfonyl hydrazide (BSH), Toluenesulfonyl hydrazide (TSH) and toluenesulfonyl hydrazide (TSH) Polypropylene foam manufacturing method, characterized in that at least one selected from the group consisting of ponyl semicarbazide (Toluenesulfonyl semicarbazide, PTSS). 6. The method of claim 5,
The blowing agent is selected from the group consisting of carbon dioxide (CO ₂ ), nitrogen (N ₂ ), hydrofluorocarbon (HFC), chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), isobutane and cyclopentane A method for producing a polypropylene foam, characterized in that at least one kind.