KR20180087906A - A Foam Composition Being Able to Mold the Foam in standard Pressure and A Molding Method Using Thereof - Google Patents

Abstract

The present invention relates to a foam composition capable of molding atmospheric pressure-type foamed articles, and a molding method using the same. To this end, the foam composition is produced by mixing a thermoplastic polymer, a crosslinking agent, a co-crosslinking agent, and a foaming agent, and a melting index (MI) of the mixture is 15-90. In addition, the molding method comprises the following steps: a first step of mixing the thermoplastic polymer, the crosslinking agent, the co-crosslinking agent, and the foaming agent in a kneader and then heating the same to produce a compound; a second step of processing the compound in a form of pellets at a temperature of 80-100°C by using an extruder; a third step of melting the pellet until an injector of an injection device reaches 150-170°C, so as to inject and foam the same; and a fourth step of injecting the composition in the third step into a mold and then molding the same while a temperature of the mold is within 50-80°C.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a foam composition capable of forming an atmospheric pressure type foam, and a molding method using the foam composition.

The present invention relates to a foam composition and a molding method using the foam composition. More particularly, the present invention relates to a foam composition capable of forming an atmospheric pressure type foam capable of injecting an amount equal to the molding mold volume into a molding mold when the foam is foamed, ≪ / RTI >

Examples of the method for producing a foam using a thermoplastic polymer include a method in which a chemical foaming agent or an inorganic foaming agent capable of generating a foaming gas at a predetermined temperature and pressure is added. At present, generally used foaming method using chemical foaming agent is a method in which a polymer is mixed with a chemical foaming agent which generates various additives and a gas to produce a compound, and the mixture is heated at a temperature higher than the decomposition temperature of the foaming agent. Press molding, injection molding, and the like correspond to press molding. Compressing the compound obtained by mixing a thermoplastic polymer, an additive, a crosslinking agent and a chemical foaming agent into a sheet or a pellet, and heating the mixture at a predetermined temperature and pressure for a certain period of time to produce a foam And the injection process is a molding method in which the pelletized compound is injected into an injection device, melted, injected into a closed mold, heated for a certain period of time, pressure-molded, and foamed. And a method in which the resin is injected into a mold which is foamed and closed in an injection using a transfer molding machine such as an injection machine.

However, the conventional method has the following problems.

There arises a problem of molding defects such as foaming relatively more than the forming mold or further foaming in the molding mold when the amount of the molding mold is directly injected into the forming mold immediately after molding the foam.

Published Japanese Patent Application No. 10-2015-0084962

An object of the present invention is to provide a foam composition capable of forming an atmospheric pressure type foam in which molding is performed safely even when the same amount of the foam is molded into the molding mold immediately after molding the foam, and a molding method using the foam composition .

In order to achieve the above object, the foam composition capable of forming atmospheric pressure type foam according to the present invention is obtained by mixing ethylene vinyl acetate (EVA), a crosslinking agent, a crosslinking aid and a foaming agent so that the mixture has a melt index .

The thermoplastic polymer is characterized by being composed of a mixture of a first thermoplastic polymer having a low melt index and a second thermoplastic polymer having a high melt index.

5 to 10 parts by weight of a foaming agent, 1 to 2 parts by weight of a capsule foaming agent, 0.15 to 0.3 parts by weight of a crosslinking agent, and 0.5 to 2.0 parts by weight of a crosslinking auxiliary to 100 parts by weight of the thermoplastic polymer.

A molding method using a foam composition capable of molding an atmospheric pressure type foam, which is another embodiment of the present invention, includes a first step of mixing a thermoplastic polymer, a crosslinking agent, a crosslinking aid and a foaming agent in a kneader and heating the mixture to prepare a compound; A third step in which the pellets are melted at an injector temperature of the injection machine of 150 to 170 DEG C and foamed while being injected; And a fourth step of molding the composition at a temperature of 30 to 60 DEG C by injecting the composition of the composition into the mold only as much as the volume of the mold.

A molding method using a foam composition capable of forming an atmospheric pressure type foam, which is another embodiment of the present invention, includes a first step of mixing a thermoplastic polymer, a crosslinking agent, a crosslinking assistant, and a foaming agent in a kneader and heating the mixture to prepare a compound; A third step of foaming the sheet at atmospheric pressure in an oven at a temperature of 150 to 180 캜, a second step of foaming the sheet at a temperature of 80 to 120 캜 using a roll, And a fourth step of injecting the composition into the mold only by the volume of the mold and molding the mold at a temperature of 30 to 60 캜.

The foam composition capable of molding an atmospheric pressure type foam according to the present invention and the molding method using the same provide the following effects.

The compound is foamed in a pellet or sheet form at a predetermined composition ratio, foamed at normal pressure, the foamed material is directly introduced into a molding mold, and the temperature is controlled at 50 to 80 ° C to prevent further foaming, There is an advantage.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing a first embodiment of a molding method using a foam composition identical to a molding mold volume according to the present invention. Fig.
Fig. 2 is a flowchart showing a second embodiment of a molding method using a foam composition identical to the molding mold volume according to the present invention. Fig.
Figure 3 shows a molding apparatus to which the method of Figure 1 is applied.

Hereinafter, preferred embodiments of a foam composition capable of forming an atmospheric pressure type foam according to the present invention and a molding method using the foam composition will be described in detail with reference to the accompanying drawings.

The foam composition capable of forming an atmospheric pressure type foam according to the present invention may be composed of a mixture of a thermoplastic polymer, a crosslinking agent, a crosslinking assistant, and a foaming agent.

First, a thermoplastic polymer is provided in the foam composition according to the present invention. The thermoplastic polymer may be at least one selected from the group consisting of ethylene vinyl acetate (EVA), ethylene vinyl acetate copolymer, low density polyethylene (LDPE), low density polyethylene copolymer (low density polyethylene) Octene Block Copolymer, Ethylene Butene Copolymer, and Ethylene Butene Copolymer) may be used.

The resin may be a mixture of two or more resins, and the melt index (MI) of the entire mixture mixed with the additives to be described below may be set within a range of 15 to 90. [

This is for the purpose of facilitating the operation when the melt index of the mixture is molded by atmospheric pressure foaming. When the melt index of the mixture is less than 15, foaming becomes unsuitable and the melt index is 90 There is a problem that the expansion ratio is excessively large or the cell is broken and the whole is difficult to be formed.

A crosslinking agent is provided in the foam composition of the present invention. The crosslinking agent may be at least one selected from the group consisting of 2,5-bis (tert-butylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tert- butylperoxy) Hexane, dibenzoyl peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tert- butylperoxy) Trimethyl chlorohexane, tert-butyl peroxybenzoate, lauryl peroxide, dicumyl peroxide, and the like.

The cross-linking agent may be mixed in an amount of 0.15 to 0.3 parts by weight based on 100 parts by weight of the thermoplastic polymer. If the amount of the cross-linking agent is less than 0.15 part by weight based on 100 parts by weight of the thermoplastic polymer, the cross-linking degree of the foam is low so that the mechanical strength is lowered as well as the loss of the foaming gas may be increased and the foam may not be formed If the amount is more than 0.3 part by weight, the crosslinking degree is high and the expansion is inhibited, resulting in a problem that the foaming cell pops up.

The foam composition according to the present invention is provided with a crosslinking aid. The crosslinking agent is added in order to prevent excessive decomposition of the thermoplastic polymer and to maintain the stability of the produced radical. The crosslinking agent may be any one selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, triallyl cyanurate, diethylene glycol dimethacrylate, Acrylate, trimethylolpropane trimethacrylate, and the like can be used. The crosslinking assistant may be mixed in an amount of 0.5 to 2.0 parts by weight based on 100 parts by weight of the thermoplastic polymer.

The foam composition according to the present invention is provided with a foaming agent. The foaming agent may be at least one selected from the group consisting of azodicarbonamide (ADCA), dinitrosopentamethylene tetramine (DPT) A toluene sulfonyl hydrazide (TSH) system, an inorganic system, and a capsule type foaming agent (Micropearl).

It is preferable that 5 to 10 parts by weight of the foaming agent and 1 to 2 parts by weight of the capsule foaming agent are mixed and applied. If the capsule foaming agent is less than 1, foaming can not be completed. If the amount is more than 2, discoloration of the capsule foaming agent becomes severe and the product can not be used as a product.

Further, an additive may be further added to the foam composition according to the present invention. The additive may be classified into a metal oxide, stearic acid, and a filler.

The metal oxide to be used in the present invention is added in order to control the crosslinking rate and promote the decomposition of the foaming agent and is added to the group consisting of zinc oxide, magnesium oxide, titanium oxide, calcium oxide, cadmium oxide, Or two or more of them may be used in combination, but it is preferable not to use oxidized cadmium, silver oxide, lead oxide, or tin oxide, which is likely to detect heavy metals, and 4 to 8 parts by weight based on 100 parts by weight of the thermoplastic polymer.

If the amount of the metal oxide is less than 4 parts by weight, the crosslinking speed and the foaming speed may be delayed. If the amount of the metal oxide is more than 8 parts by weight, the density of the foam increases and the performance may deteriorate.

The stearic acid used in the present invention is added in order to improve storage stability and processability, and it is preferable to use 0.5 to 1 part by weight based on 100 parts by weight of the thermoplastic polymer. There is a fear that it may fall or the workability may not be controlled.

The filler to be used in the present invention may be calcium carbonate, magnesium carbonate, silica, carbon black or calcium sulfate for improving the physical properties and forming a stable foam. The filler may be used in an amount of 5 to 10 parts by weight per 100 parts by weight of the thermoplastic polymer And if the amount of use is out of the above range, the above effect may not be realized.

Further, an antioxidant may be further included. The antioxidant is preferably mixed in an amount of 1 part by weight based on 100 parts by weight of the thermoplastic polymer.

Next, a molding method using a foam composition capable of forming an atmospheric pressure type foam according to the present invention will be described.

1 and 3, a first embodiment of a molding method using a foam composition capable of molding an atmospheric pressure type foam according to the present invention is a method in which a thermoplastic polymer, a crosslinking agent, a crosslinking assistant and a foaming agent are mixed in a kneader and heated, A second step of preparing the compound in the form of pellets at a temperature of 80 to 120 DEG C by using an extruder, a step of melting the pellet at an injector temperature of 150 to 170 DEG C A third step of foaming while being injected, and a fourth step of injecting the composition of the third step into the mold only by the volume of the mold and molding the mold at a temperature of 30 to 60 ° C.

In the second embodiment of the molding method using the foam composition capable of forming the atmospheric pressure type foam according to the present invention, the thermoplastic polymer, the crosslinking agent, the crosslinking aid and the foaming agent are mixed in a kneader as shown in Figs. 2 and 4 A second step of producing the compound by heating in a sheet form at a temperature of 80 to 120 캜 using a roll; and a step of heating the sheet in an oven at a temperature of 150 to 180 캜 A third step of foaming at atmospheric pressure, and a fourth step of injecting the composition of the third step into the mold only by the volume of the mold and molding the mold at a temperature of 30 to 60 캜.

Hereinafter, the present invention will be described in detail with reference to experimental results obtained by varying composition ratios of the respective compositions by a molding method according to the above-described method.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 EVA (MI: 2.5) 85 65 65 65 45 35 30 90 95 100 - - EVA (MI: 150) 35 45 45 45 55 65 70 10 5 - 100 - EVA (MI: 2.2) 100 ZnO 2 St / A 0.7 TiO2 4 Antioxidant One CaCO3 7 Cross-linking agent 0.22 Crosslinking auxiliary 1.3 blowing agent 7 Capsule foaming agent One 0.5 1.5 2.7 One One One One One - - - Melt Index 41 66 65 64 81 90 95 15 10 2.5 150 2.1

1. EVA (MI: 2.5): EVA 1328 2.5 (Hanhwa)

2. EVA (MI: 150): EVA 1528 150 (Hanwha)

3. EVA (MI: 2.2): EVA 1327 2.2 (Hanhwa)

4. Antioxidant: Songnox 1010 (Songwon Industrial)

5. Crosslinking agent: DCP

6. Crosslinking aid: TMPTMA

7. Foaming agent: ADCA

8. Capsule blowing agent: F100d (Matsumoto Chemical)

[Comparative Example 1]

In Comparative Example 1, 100 g of EVA having an MI of 2.5, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO 2, 1 g of antioxidant, 7 g of CaCO 3, 0.22 g of DCP, 1.3 g of TMPTMA and 7 g of ADCA were mixed and heated The compound was prepared in the form of pellets at a temperature of 100 ° C using an extruder. The pellets were melted at an injector temperature of 160 ° C and then foamed while being injected. The composition was injected into the mold, Lt; RTI ID = 0.0 > 45 C. < / RTI >

[Comparative Example 2]

In Comparative Example 2, 100 g of EVA having an MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO 2, 1 g of antioxidant, 7 g of CaCO 3, 0.22 g of DCP, 1.3 g of TMPTMA and 7 g of ADCA were mixed and heated The compound was prepared in the form of pellets at a temperature of 100 ° C using an extruder. The pellets were melted at an injector temperature of 160 ° C and then foamed while being injected. The composition was injected into the mold, Lt; RTI ID = 0.0 > 45 C. < / RTI >

[Comparative Example 3]

In Comparative Example 3, 100 g of EVA having an MI of 2.2, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO 2, 1 g of an antioxidant, 7 g of CaCO 3, 0.22 g of DCP, 1.3 g of TMPTMA and 7 g of ADCA were mixed and heated to prepare a compound The compound was prepared in the form of pellets at a temperature of 100 ° C using an extruder. The pellets were melted at an injector temperature of 160 ° C and then foamed while being injected. The composition was injected into the mold, Lt; RTI ID = 0.0 > 45 C. < / RTI >

[Example 1]

In Example 1, 85 g of EVA having MI of 2.5, 35 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 1 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C and then injected Foaming, molding the composition into a mold, and molding the mold at a temperature of 45 캜.

[Example 2]

In Example 2, 65 g of EVA having MI of 2.5, 45 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 0.5 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C, And the composition was injected into the mold and molded at a mold temperature of 45 캜.

[Example 3]

In Example 3, 65 g of EVA having an MI of 2.5, 45 g of EVA having an MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of an antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, And the compound was prepared in the form of pellets at a temperature of 100 DEG C using an extruder. The pellets were melted at an injector temperature of the injection machine of 160 DEG C, And the composition was injected into the mold and molded at a mold temperature of 45 캜.

[Example 4]

In Example 4, 65 g of EVA having MI of 2.5, 45 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, And the compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of the injection machine of 160 DEG C, And the composition was injected into the mold and molded at a mold temperature of 45 캜.

[Example 5]

In Example 5, 45 g of EVA having MI of 2.5, 55 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 1 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C and then injected Foaming, molding the composition into a mold, and molding the mold at a temperature of 45 캜.

[Example 6]

In Example 6, 35 g of EVA having MI of 2.5, 65 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 1 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C and then injected Foaming, molding the composition into a mold, and molding the mold at a temperature of 45 캜.

[Example 7]

In Example 7, 30 g of EVA having MI of 2.5, 70 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 1 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C and then injected Foaming, molding the composition into a mold, and molding the mold at a temperature of 45 캜.

[Example 8]

In Example 8, 90 g of EVA having an MI of 2.5, 10 g of EVA having an MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of an antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 1 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C and then injected Foaming, molding the composition into a mold, and molding the mold at a temperature of 45 캜.

[Example 9]

In Example 9, 95 g of EVA having MI of 2.5, 5 g of EVA having MI of 150, 2 g of ZnO, 0.7 g of St / A, 4 g of TiO2, 1 g of antioxidant, 7 g of CaCO3, 0.22 g of DCP, 1.3 g of TMPTMA, 1 g were mixed in a kneader and heated to prepare a compound. The compound was prepared in the form of pellets at a temperature of 100 DEG C by using an extruder. The pellets were melted at an injector temperature of 160 DEG C and then injected Foaming, molding the composition into a mold, and molding the mold at a temperature of 45 캜.

Table 2 shows the results of the specific gravity and hardness and the results of examining the molding conditions after the injection of the foam into the mold.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 importance 0.210 0.205 0.200 0.211 0.214 0.201 0.200 0.199 0.199 0.200 0.198 0.199 Hardness 51 50 50 52 53 50 50 50 50 50 49 50 Whether it is molded ○ ○ ○ ○ ○ ○ △ ○ △ X X X Melt Index 41 66 65 64 81 90 95 15 10 2.5 150 2.1

As shown in Table 2, in the case of Examples 1 to 6 and Example 8, no deformation occurred as a result of molding by injecting the foam in accordance with the volume of the mold. In Comparative Examples 1 to 3, however, . In the case of Examples 7 and 9, the frequency of occurrence of deformation during molding was high.

As a result, it is judged that there is no change in the physical properties due to the similar specific gravity and hardness as a whole, and it is possible to mold the foam directly into the mold within the range of 15 to 90 in the range of the melt index. However, It is possible to obtain a result that is high or can not be formed at all.

It is to be understood that the invention is not limited to the disclosed embodiment, but is capable of many modifications and variations within the scope of the appended claims. It is self-evident.

Claims (5)

Wherein the mixture has a melt index (MI) of 15 to 90 by mixing a thermoplastic polymer, a crosslinking agent, a crosslinking aid and a foaming agent. The method according to claim 1,
The thermoplastic polymer
A first thermoplastic polymer having a low melt index and
And a second thermoplastic polymer having a high melt index is mixed with the first thermoplastic polymer and the second thermoplastic polymer. The method according to claim 1,
With respect to 100 parts by weight of the thermoplastic polymer,
5 to 10 parts by weight of a foaming agent,
1 to 2 parts by weight of a capsule foaming agent,
0.15 to 0.3 parts by weight of a crosslinking agent,
And 0.5 to 2.0 parts by weight of a crosslinking auxiliary. A first step of mixing a thermoplastic polymer, a crosslinking agent, a crosslinking aid and a foaming agent in a kneader and heating the mixture to prepare a compound;
A second step of preparing the compound in the form of pellets at a temperature of 80 to 120 DEG C by using an extruder;
A third step of melting the pellet at a temperature of 150 to 170 DEG C and injecting the pellet while the injector is being injected;
And a fourth step of injecting the composition of the third step into the mold only by the volume of the mold and molding the mold at a temperature of 30 to 60 ° C. Using molding method. A first step of mixing a thermoplastic polymer, a crosslinking agent, a crosslinking aid and a foaming agent in a kneader and heating the mixture to prepare a compound;
A second step of lowering the compound in a sheet form at a temperature of 80 to 120 캜 using a roll;
A third step of foaming the sheet at atmospheric pressure in an oven at a temperature of 150 to 180 DEG C;
And a fourth step of injecting the composition of the third step into the mold only by the volume of the mold and molding the mold at a temperature of 30 to 60 DEG C. 4. A molding method using a foam composition capable of forming an atmospheric pressure type foam.

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