KR20230141077A - Manufacturing method of irradiation cross-linked foam using non-harmful foaming agent and non-harmful irradiation cross-linked foam manufactured therefrom - Google Patents

Abstract

The present invention provides a method for producing an electron beam cross-linked foam that is harmless to the human body, and (S1) a foam raw material composition containing 100 parts by weight of a base resin, 0.1 to 5.0 parts by weight of a cross-linking aid, and 2 to 50 parts by weight of a sodium bicarbonate blowing agent is extruded. manufacturing an extruded sheet by melting and extruding the product; (S2) crosslinking the base resin by irradiating the extruded sheet with an electron beam; and (S3) heating the result of (S2) to foam the sodium bicarbonate foaming agent.

Description

Manufacturing method of electron beam cross-linked foam using non-harmful foaming agent and non-harmful irradiation cross-linked foam manufactured therefrom}

The present invention relates to a method of producing an electron beam cross-linked foam using a foaming agent harmless to the human body and to an electron beam cross-linked foam produced therefrom.

Foams are used in automotive interior materials such as door trims and instrument panels, and as sealing materials or shock absorbers such as window tape for electronic products such as Flat Panel Display (FPD) and Touch Screen Panel (TSP) devices. It is used for various purposes.

Foam is manufactured by melting and extruding a resin composition containing a foaming agent through an extruder, then performing crosslinking and foaming the resin composition.

Various types of foaming agents are known, but azodicarbonamide (ADCA) is commonly used. ADCA is decomposed during the foaming process as shown in the formula below, and foaming is achieved by the gas generated from this. However, when ADCA is decomposed, formamide and ammonia are generated as by-products, raising concerns about its toxicity to the human body.

Formamide is irritating to the eyes, skin, and mucous membranes and may require medical attention if large amounts of formamide vapor are inhaled. It is also known as a substance that causes deformities.

Ammonia is corrosive and, if swallowed, can cause burns to the mouth, throat and stomach, and in severe cases can cause death. Additionally, it can cause sore throat, vomiting, and diarrhea. Skin contact can cause pain, redness, severe inflammation or third-degree burns due to corrosion by the base.

Accordingly, there is a need for a method of manufacturing foam using a foaming agent that is harmless to the human body without using azodicarbonamide.

The purpose of the present invention is to provide a method for producing foam, especially electron beam crosslinked foam, using a foaming agent that is harmless to the human body.

Another object of the present invention is to provide an electron beam crosslinked foam that is harmless to the human body manufactured by a method of producing an electron beam crosslinked foam using a foaming agent that is harmless to the human body.

Other objects and advantages of the present invention may be understood by the following description. Meanwhile, it will be readily apparent that the objects and advantages of the present invention can be realized by means or methods described in the patent claims, and combinations thereof.

The first aspect of the present invention is,

(S1) preparing an extruded sheet by putting a foam raw material composition containing 100 parts by weight of a base resin, 0.1 to 5.0 parts by weight of a crosslinking aid, and 2 to 50 parts by weight of a sodium bicarbonate foaming agent into an extruder and melt-extruding it;

(S2) crosslinking the base resin by irradiating the extruded sheet with an electron beam; and

(S3) heating the result of (S2) to foam the sodium bicarbonate foaming agent; providing a method for producing an electron beam crosslinked foam that is harmless to the human body, including the step.

The second aspect of the present invention is, in the first aspect,

A method for producing an electron beam cross-linked foam harmless to the human body is provided, wherein the base resin is polyolefin.

The third aspect of the present invention is that, in the second aspect,

The polyolefin provides a method for producing an electron beam cross-linked foam harmless to the human body, characterized in that the polyolefin is a mixture of polypropylene and polyethylene.

The fourth aspect of the present invention is,

An electron beam cross-linked foam harmless to the human body manufactured according to the manufacturing method of an electron beam cross-linked foam harmless to the human body according to the above-mentioned aspects,

The density is 70 to 500 g/L,

Provided is an electron beam cross-linked foam that is harmless to the human body and has a thickness of 0.1 to 10 mm.

According to the manufacturing method of the electron beam cross-linked foam harmless to the human body according to the present invention, by using sodium bicarbonate foam as a foaming agent, components harmful to the human body, such as azodicarbonamide (ADCA), are not released when the foam is decomposed.

Accordingly, it is possible to provide an electron beam crosslinked foam that is harmless to the human body during the manufacturing process or even after manufacturing.

Terms or words used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

According to the manufacturing method of the electron beam crosslinked foam harmless to the human body of the present invention,

First, a foam raw material composition containing 100 parts by weight of base resin, 0.1 to 5.0 parts by weight of crosslinking aid, and 2 to 50 parts by weight of sodium bicarbonate blowing agent is put into an extruder and melt-extruded to prepare an extruded sheet (step S1).

The base resin can be varied depending on the purpose of the electron beam crosslinked foam. For example, polyolefin resins such as polyethylene resin and polypropylene resin can be used alone or in combination, and in addition to polyolefin resin, polyurethane resin, Resins used in electron beam cross-linked foams, such as polyacrylic resin and polyvinyl chloride resin, can be used as the base resin.

For example, when polyethylene resin and polypropylene resin are mixed, they can be mixed at a content ratio of 1:9 to 9:1, but are not limited thereto. Within this content range, the advantages of polypropylene-based resins, such as excellent heat resistance, and the advantages of polyethylene-based resins, such as excellent flexibility and ease of foam production, can be exhibited at the same time.

Here, the polypropylene resin may be a mixture of a polypropylene homo-copolymer (homo-copolymer) and a copolymer containing polypropylene as a main component. At this time, the copolymer containing polypropylene as the main component is an α-olefin copolymer (random or block copolymer) containing more than 85% polypropylene or a terpolymer (ter polymer) in which two types of α-olefin are copolymerized. Examples of the α-olefin include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, and 1-pentene.

Polyethylene resins include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene polyethylene, ethylene-propylene rubber (EPR), and ethylene-propylene diene monomer (EPDM). ) copolymers, etc. may be exemplified, but are not limited thereto.

By containing 0.1 to 5.0 parts by weight of the crosslinking aid, an appropriate crosslinking degree of 10 to 50% can be maintained. The crosslinking aid may be any one selected from the group consisting of vinyl monomers, acrylic compounds, methacrylic compounds, and epoxy compounds, or a mixture of two or more of them.

Sodium bicarbonate foam is decomposed according to the following chemical formula through the foaming process.

The decomposed ingredients are harmless to the human body. In other words, unlike ADCA, it does not emit substances harmful to the human body such as formamide.

The foam raw material composition may include, if necessary, a cadmium compound, a calcium compound, a zinc compound, a magnesium compound, an iron compound, a copper compound, and Additional foaming aids such as the same can be added.

Additionally, the foam raw material composition may further include 1 to 30 parts by weight of an inorganic material based on 100 parts by weight of the base resin. Here, the inorganic material is located between cells formed inside the extruded sheet, and plays a role in improving the size of the cells by connecting independent cells to each other during the stretching process, thereby further improving the flexibility of the foam. The inorganic material that can be used at this time may be any one selected from the group consisting of silicon compounds, magnesium compounds, calcium compounds, and carbon black, or a mixture of two or more of these.

In addition, the foam raw material composition may further include 1 to 3 parts by weight of an antioxidant based on 100 parts by weight of the base resin. Within this content range, it is advantageous to maintain good processability, economic efficiency, and mechanical properties of the product during extrusion and foaming. The antioxidant that can be used at this time may be any one selected from the group consisting of phenol-based, amino-based, phosphorus-based, and sulfur-based, or a mixture of two or more of these.

The foam raw material composition is melt-extruded to produce an extruded sheet. Regarding the extruder, a single extruder can be used, but it is preferred to use a twin extruder. The twin extruder can be of both the counter-rotation type and the co-rotation type, but more desirable extrusion performance can be secured by using the latter co-rotation type twin extruder.

The number of kneading blocks among the screws inside the twin extruder cylinder can be adjusted to about 10 to 40%, and if it does not reach the lower limit of the numerical range, the kneading property of the introduced resin composition decreases, and the upper limit of the numerical range is lowered. If it is exceeded, the performance of the foaming agent may deteriorate.

Next, the base resin is crosslinked by irradiating the extruded sheet with an electron beam (step S2).

At this time, for example, a crosslinking degree of 10 to 50% can be obtained by irradiating an accelerated electron beam with a voltage of 100 to 1,000 kV and an electron dose of 0.5 to 10 Mrad.

Next, the result of (S2) is heated to foam the sodium bicarbonate foaming agent in the electron beam crosslinked base resin (step S3).

The foaming step may be performed by any one of the following: a horizontal foaming method in which the foaming furnace is installed horizontally, a vertical foaming method in which the foaming furnace is installed vertically, and a salt foaming method that uses liquid salt as a heat transfer medium. However, vertical foaming It is preferable to stretch while using the method.

At this time, the result of (S2) can be foamed while being stretched so that the stretch ratio in the width direction is 1.0 to 3.0 times and the stretch ratio in the longitudinal direction is 2.0 to 10.0 times. By satisfying the above numerical range, an ultra-thin electron beam crosslinked foam can be obtained.

The extrusion sheet retraction speed may be 1 to 5 m/min, the withdrawal speed may be 3 to 50 m/min, and the heating temperature may be 180 to 300°C. By maintaining the drawing speed and drawing speed, the extruded sheet is foamed/stretched, making it possible to obtain a foam of increased length without difficulty.

The thickness of the foam produced by this method may be, for example, 0.1 to 10 mm and the density may be 70 to 500 g/L, but are not limited thereto.

Claims (4)

(S1) preparing an extruded sheet by putting a foam raw material composition containing 100 parts by weight of a base resin, 0.1 to 5.0 parts by weight of a crosslinking aid, and 2 to 50 parts by weight of a sodium bicarbonate foaming agent into an extruder and melt-extruding it;
(S2) crosslinking the base resin by irradiating the extruded sheet with an electron beam; and
(S3) heating the result of (S2) to foam the sodium bicarbonate foaming agent. According to paragraph 1,
A method of producing an electron beam cross-linked foam harmless to the human body, characterized in that the base resin is polyolefin. According to paragraph 2,
A method of producing an electron beam crosslinked foam harmless to the human body, characterized in that the polyolefin is a mixture of polypropylene and polyethylene. An electron beam cross-linked foam harmless to the human body manufactured according to the method for producing the electron beam cross-linked foam harmless to the human body according to any one of claims 1 to 3,
The density is 70 to 500 g/L,
An electron beam cross-linked foam harmless to the human body with a thickness of 0.1 to 10 mm.