KR101669196B1 - Environment-friendly foam sheet - Google Patents

Abstract

Environmentally friendly foamed sheets that are foamed using a foaming agent after mixing aliphatic polycarbonate, chain extenders and nucleating agents are free of dioxin emission at the time of disposal and can be used for foods or building materials because of their high degree of expansion and uniform foaming It is possible.

Description

{ENVIRONMENT-FRIENDLY FOAM SHEET}

The present invention relates to an eco-friendly foam sheet used for food packaging materials or building materials.

BACKGROUND OF THE INVENTION [0002] A foam sheet used as a heat-insulating material for food containers and building materials is mainly composed of a polyethylene-based resin, a polypropylene-based resin, and a polystyrene-based resin. In particular, the polystyrene-based foamed resin is light in weight and has excellent heat insulation, but has a problem of causing environmental pollution such as generation of dioxin upon incineration.

Accordingly, it is required to develop an environmentally friendly foam sheet capable of high magnification and uniform foaming, and free from dioxin emission during disposal.

Accordingly, an object of the present invention is to provide an eco-friendly foam sheet which can be used for food packaging or building materials and which is free from dioxin emissions at the time of disposal, and which can be produced at high power and uniform foaming.

Another object of the present invention is to provide a packaging material or a foamed molded product comprising the foamed sheet.

According to the above object, the present invention provides an eco-friendly foamed sheet produced by mixing an aliphatic polycarbonate resin, a chain extender and a nucleating agent, followed by foam molding using a foaming agent.

According to another aspect of the present invention, there is provided a foam sheet composition comprising: (a1) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender, a nucleating agent, and a foaming agent; (b1) heating and melt kneading the composition for forming a foamed sheet to prepare a melt-kneaded product; (c1) cooling the melt-kneaded product; And (d1) extruding and blowing the cooled melt-kneaded product.

According to another aspect of the present invention, there is provided a foam sheet composition comprising: (a2) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender, and a nucleating agent; (b2) heating and melt kneading the composition for forming a foamed sheet while adding a foaming agent to prepare a melt-kneaded product; (c2) cooling the melt-kneaded product; And (d2) extruding and blowing the cooled melt-kneaded product.

The present invention also provides a packaging material or a foamed molded article comprising the environmentally friendly foam sheet.

The eco-friendly foam sheet according to the present invention can be used for foods or building materials because of its high magnification and uniform foaming, and there is no fear of dioxin emission at the time of disposal.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a process for producing an environmentally friendly foam sheet useful as a food or a building material without the fear of dioxin emission at the time of disposal at a high magnification and uniform foaming by adding an aliphatic polycarbonate as a main component and adding a chain extender and a nucleating agent .

That is, the environmentally friendly foam sheet according to the present invention is produced by mixing (a) an aliphatic polycarbonate resin, (b) a chain extender, (c) a nucleating agent, and (d) foam molding using a foaming agent. Depending on the use of the foam sheet, it may further contain (e) additives.

Hereinafter, each component used for manufacturing the environmentally friendly foam sheet of the present invention will be described in detail.

(a) an aliphatic polycarbonate resin

The aliphatic polycarbonate resin may be prepared by copolymerizing carbon dioxide with an epoxide compound selected from the group consisting of alkylene oxides, cycloalkene oxides, and mixtures thereof. As the polymerization catalyst, a zinc precursor such as diethyl zinc, a complex compound containing an onium salt (Korea Patent No. 0853358), a cobalt catalyst, and a zinc catalyst may be used.

Specific examples of the epoxide compound include ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene monoxide, , 2-epoxide-7-octene, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, 2,3-epoxide norbornene, limonene oxide and mixtures thereof.

The pressure of the carbon dioxide in the aliphatic polycarbonate resin copolymerization may be atmospheric pressure to 100 atm, preferably 5 to 30 atm. In addition, the polymerization temperature may be 20 to 120 캜, preferably 50 to 90 캜.

Examples of the method of copolymerizing the aliphatic polycarbonate resin include a batch polymerization method, a semi-batch polymerization method, and a continuous polymerization method. In the case of using the batch or semi-batch polymerization method, the reaction time may be from 1 to 24 hours, preferably from 1.5 to 4 hours, and when the continuous polymerization method is used, the average residence time of the catalyst is also from 1.5 to 4 hours .

Specific examples of the aliphatic polycarbonate resin include polyethylene carbonate, polypropylene carbonate, and mixtures thereof.

The number average molecular weight (Mn) of the aliphatic polycarbonate resin used in the present invention may be 50,000 to 500,000. Here, the number average molecular weight (Mn) means the number average molecular weight measured by GPC after correcting polystyrene of a single molecular weight distribution with a standard material.

In general, aromatic polycarbonates are very dangerous from the manufacturing process because they are produced using toxic substances such as bisphenol A and phosgene, while aliphatic polycarbonates utilize carbon dioxide, which contributes to the reduction of carbon dioxide emitted to the atmosphere There are also advantages. In addition, the aromatic polycarbonate does not decompose spontaneously and emits environmentally harmful substances upon incineration, but aliphatic polycarbonate can be decomposed into carbon dioxide and water even when incinerated.

It is preferable that the aliphatic polycarbonate resin is used in an amount of 60 to 99.9% by weight based on the total weight of the composition for forming a foam sheet because a uniform and sufficient foaming effect can be obtained. When the content of the aliphatic polycarbonate resin is less than 60% by weight, the foaming magnification is too low, which is undesirable. When the content of the aliphatic polycarbonate resin is more than 99.9% by weight, crystallinity is deteriorated, not.

(b) chain extender

The chain extender serves to increase the molecular weight of the aliphatic polycarbonate during the production of the foam sheet to increase the mechanical strength and to increase the melt index of the aliphatic polycarbonate to a melt index suitable for sheet extrusion.

Specific examples of the chain extender include isocyanate compounds such as hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate and triisocyanate; Or an acrylic compound having an epoxy functional group. These may be used alone or in combination of two or more.

The chain extender is preferably used in an amount of 0.01 to 20% by weight based on the total weight of the composition for forming a foam sheet. When the content of the chain extender is less than 0.01% by weight, it is not easy to prepare the composition in the form of a sheet. If the content of the chain extender is more than 20% by weight, the viscosity may increase rapidly due to excessive cross-linking.

(c)

The nucleating agent serves to induce foaming of the aliphatic polycarbonate resin, and may be formed of inorganic materials such as talc and silica; Or organic materials such as calcium stearate. The nucleating agent may be added per se or may be mixed with the aliphatic polycarbonate resin and added in the form of a master batch.

The nucleating agent is preferably used in an amount of 0.01 to 20% by weight based on the total weight of the composition for forming a foam sheet. When the content of the nucleating agent is less than 0.01% by weight, the foaming magnification is not so large, non-uniform foaming occurs, and crystallization is not induced, which may cause fusion of the expanded particles in molding in the mold. On the other hand, when the content is more than 20% by weight, the melt adhesion is reduced in the foaming molding but the mechanical properties of the foam sheet are rapidly lowered and the stiffness is increased as the content of the inorganic substance is increased.

(d) blowing agent

Examples of the foaming agent include azodicarbonamide, a mixture of citric acid and sodium bicarbonate, zinc-ditoluenesulfinite, 5-phenyltetrazole, chemical foaming agents such as p-toluenesulfonylsemicarbazide, N, N-dinitrosopentamethylene tetramine, and benzenesulfonylhydrazide; Or gas blowing agents such as carbon dioxide, nitrogen, argon, air, butane, and pentane.

(e) Additive

The foam sheet according to the present invention may further contain, in addition to the above components, additives such as a dispersant (for example, stearamide) for increasing the dispersibility of the nucleating agent.

The additive may be appropriately included within the range not impairing the object of the present invention. Specifically, the additive is preferably used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the composition for forming a foamed sheet.

The foam sheet according to the present invention made of the above-mentioned components has a specific gravity of 1.30 or less, more preferably 0.5 to 1.30. If the specific gravity exceeds 1.30, void formation through foaming may not be performed, which is not preferable.

The foam sheet according to the present invention has a strength of 3 kgf / mm ² or more, and more preferably 3 to 20 kgf / mm ² . If the strength is less than 3 kgf / mm < ^{2 >,} cracks may easily occur due to impact, which is not preferable.

The foam sheet according to the present invention has a modulus of 30 to 500 kgf / mm ² . When the modulus is less than 30 kgf / mm ² , it is not preferable since it is easily deformed by an external impact or easily broken or broken. When the modulus exceeds 500 kgf / mm ² , the hardness of the sheet is increased, It is undesirable because there is a possibility that it may be deteriorated.

The foam sheet according to the present invention preferably has a thickness of 500 탆 or more.

The environmentally friendly foam sheet of the present invention can be produced by mixing an aliphatic polycarbonate resin, a chain extender, and a nucleating agent, followed by foam molding using a foaming agent.

Specifically, in the case of using a chemical foaming agent, the environmentally friendly foam sheet according to the present invention comprises (a1) an aliphatic polycarbonate resin, a chain extender, a nucleating agent, and a chemical agent Mixing a foaming agent to prepare a composition for forming a foam sheet; (b1) heating and melt kneading the composition for forming a foamed sheet to prepare a melt-kneaded product; (c1) cooling the melt-kneaded product; And (d1) extruding and blowing the cooled molten kneaded product.

In the case of using a gas blowing agent, the environmentally friendly foam sheet according to the present invention comprises: (a2) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender and a nucleating agent; (b2) heating and melt kneading the composition for forming a foamed sheet while injecting a gas blowing agent to prepare a melt-kneaded product; (c2) cooling the melt-kneaded product; And (d2) extruding and blowing the cooled melt kneaded product.

The types and contents of the aliphatic polycarbonate resin, chain extender and nucleating agent used in the above steps (a1) and (a2) are the same as those described above.

In the above steps (b1) and (b2), the melt-kneading step is preferably carried out in an extruder or an extrusion foaming machine, and the temperature is preferably 130 to 280 ° C.

The chemical foaming agent or gas foaming agent used in the above steps (a1) and (b2) is the same as described above.

In the above-mentioned steps (c1) and (c2), the cooling temperature is preferably 30 DEG C or less.

The foam sheet produced by the above-described production method contains an aliphatic polycarbonate as a main component, so there is no fear of dioxin emission at the time of disposal, and the aliphatic polycarbonate is uniformly foamed at a high magnification and is useful for food packaging materials or building materials Do.

Accordingly, the present invention also provides a packaging material or a foamed molded body comprising the above foam sheet.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only illustrative of the present invention, and the present invention is not necessarily limited thereto.

Example  1: Production of foam sheet

After mixing with the compositions shown in Table 1 below, they were foam-molded to prepare foamed sheets.

Specifically, 94 wt% of polypropylene carbonate (PPC, Empower, QPAC40), 3 wt% of an acrylic compound having an epoxy functional group (Johnson Polymer Co., ADR4368) as a chain extender, Mu m) were mixed in a mixer and mixed well to prepare a composition for forming a foamed sheet. The prepared composition was supplied to the pressure starting furnace and melted and kneaded by heating at 190 DEG C while feeding CO ₂ as a blowing agent into the pressure starting furnace to prepare a melt kneaded product. The resulting melt-kneaded product was cooled to 10 DEG C and extruded from a cyclic die to foam, and the resultant foam was cooled while being discharged in the take-out and extrusion directions to obtain a foamed sheet.

Example  2: Production of foam sheet

After mixing with the compositions shown in Table 1 below, they were foam-molded to prepare foamed sheets.

Specifically, a mixture of 80% by weight of polyethylene carbonate (PPC, Empower, QPAC40), 7% by weight of an acrylic compound having an epoxy functional group as a chain extender (Johnson Polymer Co., ADR4368), a mixture of talc and silica (UNICELL C # 709MT) as a foaming agent and 3 wt% of a mixture of citric acid and sodium bicarbonate (weight ratio: 50:50) as a foaming agent were mixed and mixed well to prepare a composition for forming a foamed sheet. The prepared composition was supplied to the pressure starting furnace and heated to 190 캜 and melt-kneaded to prepare a melt-kneaded product. The resulting melt-kneaded product was cooled to 10 DEG C and extruded from a cyclic die to foam, and the resultant foam was cooled while being discharged in the take-out and extrusion directions to obtain a foamed sheet.

Comparative Example  1: Production of foam sheet

A foam sheet was obtained in the same manner as in Example 1, except that each component was mixed with the composition shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Aliphatic
Polycarbonate Polypropylene carbonate (94% by weight) Polyethylene carbonate
(80% by weight) Expanded polystyrene
(100% by weight) Chain extender Acrylic compound having an epoxy functional group
(3% by weight) Epoxy-functional
Acrylic compound
(7% by weight) - Nucleophilic agent Talc
(3% by weight) Mixture of talc and silica
(10% by weight) - blowing agent Gas blowing agent (CO ₂ ) Chemical foaming agents (citric acid and
Mixture of sodium bicarbonate)
(3% by weight) Gas blowing agent (butane)

Test Example

The properties of the foamed sheets prepared in the above Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 2 below.

(1) Specific gravity

The specific gravity of the foam sheet prepared in Examples and Comparative Examples was measured using a density sphere pipe.

(2) Foaming uniformity

The foaming sheets prepared in Examples and Comparative Examples were observed using a scanning electron microscope to determine whether the foam cell size was uniform.

(3) Heat resistance

The foamed sheets prepared in Examples and Comparative Examples were immersed in water at 50 캜 for 3 minutes, and changes in sheet shape were visually observed and classified according to the following criteria.

Good: No change in shape

Defective: severe form change

(4) Strength and Modulus

The strength and modulus of the foam sheet prepared in Examples and Comparative Examples were measured using a tensile universal testing machine (UTM 4206-001, INSTRON) according to ASTM D 882. Specifically, the foam sheet was cut at a distance of 5 cm or more in the direction orthogonal to the main shrinkage direction of the foam sheet sample and 15 mm in the main shrinkage direction, and then attached to a clip of 5 cm apart, stretched at room temperature, The curve was obtained. (Kgf / mm ² ), and the modulus (kgf / mm ² ) obtained from the stress-strain gradient was defined as the force applied when the fracture per unit area occurred.

Example 1 Example 2 Comparative Example 1 importance 1.2 1.0 0.9 Foam uniformity Uniformity Uniformity Uniformity Heat resistance Good Good Good Strength (kgf / mm ² ) 3.5 4.0 2.0 Modulus (kgf / mm ² ) 300 250 550

As can be seen from the above Table 2, the foam sheets of Examples 1 and 2 exhibited the same effects in terms of specific gravity, foam uniformity and heat resistance as compared with the foam sheet of Comparative Example 1, but the strength was increased and the modulus And it was more excellent in impact resistance.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It is to be understood that the invention may be practiced within the scope of the appended claims.

Claims (16)

(a1) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender, a nucleating agent and a foaming agent;
(b1) heating and kneading the composition for forming a foamed sheet at 130 to 280 DEG C to prepare a melt-kneaded product;
(c1) cooling the melt-kneaded product to 30 DEG C or lower; And
(d1) extruding and blowing the cooled melt-kneaded product,
Wherein the blowing agent is selected from the group consisting of azodicarbonamide, a mixture of citric acid and sodium bicarbonate, zinc-di-toluenesulfinate, 5-phenyltetrazole, p- toluenesulfonylsemicarbazide, N, N-dinitrosopentamethylenetetramine, Sulfonyl hydrazide, and is a chemical foaming agent selected from the group consisting of
Wherein the composition for forming a foam sheet comprises from 60 to 99.9% by weight of an aliphatic polycarbonate resin, from 0.01 to 20% by weight of a chain extender and from 0.01 to 20% by weight of a nucleating agent.
(a2) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender and a nucleating agent;
(b2) melt-kneading the composition for forming a foamed sheet at 130 to 280 DEG C while adding a foaming agent to prepare a melt-kneaded product;
(c2) cooling the molten kneaded product to 30 DEG C or lower; And
(d2) extruding and blowing the cooled melt-kneaded product,
Wherein the blowing agent is a gas blowing agent selected from the group consisting of carbon dioxide, nitrogen, argon, air, butane and pentane,
Wherein the composition for forming a foam sheet comprises from 60 to 99.9% by weight of an aliphatic polycarbonate resin, from 0.01 to 20% by weight of a chain extender and from 0.01 to 20% by weight of a nucleating agent.
3. The method according to claim 1 or 2,
Wherein the aliphatic polycarbonate resin is obtained by copolymerization of carbon dioxide with an epoxide compound selected from the group consisting of alkylene oxides, cycloalkene oxides, and mixtures thereof.
3. The method according to claim 1 or 2,
Wherein the aliphatic polycarbonate resin is selected from the group consisting of polyethylene carbonate, polypropylene carbonate, and mixtures thereof.
3. The method according to claim 1 or 2,
Wherein the aliphatic polycarbonate resin has a number average molecular weight (Mn) of 50,000 to 500,000.
3. The method according to claim 1 or 2,
Wherein the chain extender is selected from the group consisting of an isocyanate compound, an acrylic compound, and a mixture thereof.
3. The method according to claim 1 or 2,
Wherein the nucleating agent is selected from the group consisting of talc, silica, calcium stearate, and mixtures thereof.
3. The method according to claim 1 or 2,
Wherein the foam sheet has a specific gravity of 1.30 or less.
3. The method according to claim 1 or 2,
Wherein the foam sheet has a strength of 3 to 20 kgf / mm ² .
3. The method according to claim 1 or 2,
Wherein the foam sheet has a modulus of 30 to 500 kgf / mm < ² >.
(a1) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender, a nucleating agent and a foaming agent;
(b1) heating and kneading the composition for forming a foamed sheet at 130 to 280 DEG C to prepare a melt-kneaded product;
(c1) cooling the melt-kneaded product to 30 DEG C or lower; And
(d1) extruding and foaming the cooled melt kneaded product,
Wherein the blowing agent is selected from the group consisting of azodicarbonamide, a mixture of citric acid and sodium bicarbonate, zinc-di-toluenesulfinate, 5-phenyltetrazole, p- toluenesulfonylsemicarbazide, N, N-dinitrosopentamethylenetetramine, Sulfonyl hydrazide, and is a chemical foaming agent selected from the group consisting of
The method for producing a foamed sheet according to claim 1, wherein the composition for forming a foamed sheet comprises 60 to 99.9% by weight of an aliphatic polycarbonate resin, 0.01 to 20% by weight of a chain extender and 0.01 to 20% by weight of a nucleating agent.
delete (a2) preparing a composition for forming a foam sheet by mixing an aliphatic polycarbonate resin, a chain extender and a nucleating agent;
(b2) melt-kneading the composition for forming a foamed sheet at 130 to 280 DEG C while adding a foaming agent to prepare a melt-kneaded product;
(c2) cooling the molten kneaded product to 30 DEG C or lower; And
(d2) extruding and foaming the cooled melt kneaded product,
Wherein the blowing agent is a gas blowing agent selected from the group consisting of carbon dioxide, nitrogen, argon, air, butane and pentane,
The method for producing a foamed sheet according to claim 2, wherein the composition for forming a foamed sheet comprises 60 to 99.9% by weight of an aliphatic polycarbonate resin, 0.01 to 20% by weight of a chain extender and 0.01 to 20% by weight of a nucleating agent.
delete A packaging material comprising the foam sheet according to claim 1 or 2.
A foamed molded product comprising the foam sheet according to any one of claims 1 to 3.