KR101584133B1 - Expanded articles using different types of expanded particles and process for producing the same - Google Patents

Abstract

The present invention relates to a uniform composite foaming molded article using different kinds of foamed particle, and to a production method thereof. according to the present invention, in terms of the composite foaming molded article formed by fusion of two or more different kinds of foamed particles, in the composite foaming molded article, uniformly mixed are a secondary foamed particle of high density preliminary foamed particle which is relatively has large density while being in a preliminary foamed particle form, and a secondary foamed particle of a coated low density preliminary foamed particle on which a coating layer capable of increasing density is formed on a surface of the low density preliminary particle which is relatively low in density when being in the preliminary foamed particle form. Provided is the uniform composite foamed molded article using different kinds of foamed particles.

Description

[0001] The present invention relates to a composite foamed article and a method of manufacturing the same,

The present invention relates to a molded article using expanded particles and a method for producing the same, and more particularly, to a method for manufacturing a molded article using expanded particles, which comprises the steps of blending dissimilar foamed particles having different densities and characteristics, And to a method for producing the same.

BACKGROUND OF THE INVENTION [0002] A foamed molded article using expanded particles such as expanded polystyrene is light in weight, and is widely used for packaging materials, building materials, and the like because it is excellent in water resistance, heat insulation, sound absorbing property and buffering property.

The foamed molded product may be prepared by prefoaming a foamed resin particle containing a foaming agent supplied in the form of a small bead having a diameter of 0.2 to 0.3 mm or a pellet having a length of about 2.5 mm, And then pre-agglomerating and drying the pre-expanded beads. The pre-agglomerated pre-expanded beads are put into a mold, heated with high temperature and high pressure steam, and molded into a desired shape.

The foamed molded article thus produced generally has 98% of the total volume of air, accounts for only about 2% of the resin, and has a unique foam structure in which the air is sealed in the foam of the polymer resin. Therefore, excellent foamability, heat insulation, sound- Sex and so on.

In recent years, in order to impart special functionality to such foamed molded articles, various types of foamable particles having various functional additives added thereto have been supplied. For example, Korean Patent Registration No. 10-0801275 discloses a method for preparing a micropellet comprising the steps of mixing a graphite particle with a styrene resin to prepare a mixed composition, and extruding the composition to obtain micropellets of suspendable and uniform particles; And a step of suspending the micropellets containing graphite in water, adding a styrene monomer and a C6 to C10 aromatic hydrocarbon to perform nucleation polymerization, and injecting a blowing agent to impregnate the micropellets with water, thereby producing foamed polystyrene particles having excellent adiabatic properties WO 98/51735 discloses a particulate expandable styrene polymer which comprises homogeneously dispersed graphite particles and which can provide a self-expanding foam having a density of 35 g / liter or less. Also, Korean Patent Laid-Open Publication No. 10-2010-0085069 discloses a foamable material comprising an opaque particle selected from the group consisting of carbon black, graphite, aluminum powder, titanium dioxide, and mixtures thereof encapsulated by at least one vulcanized rubber Styrene polymer and a foam having a density of 5 to 200 g / l produced by foaming the styrene polymer.

As in the above-mentioned inventions, the foams can be improved to some extent by the addition of various functional additives, but the foaming resin to which such a functional additive is added has a problem that the price is too high or the formability is poor Or the mechanical properties and shape of the molded product obtained by the addition of the functional additive may become poor.

Therefore, in order to compensate for deficient physical properties other than the above-mentioned improved performance, it is necessary to prepare a composite foamed article by mixing with other foamed particles.

However, it is not easy to produce a composite foamed article by mixing foamed particles of different properties, that is, different kinds of foamed particles, in order to improve the performance or the function of the deteriorated physical properties, Particularly, it is very difficult to obtain a composite foamed article in which different kinds of expanded particles are uniformly distributed due to the difference in specific gravity between them in the state of prefoamed particles.

That is, as described above, the foamed molded article such as foamed polystyrene is foamed first to obtain prefoamed particles capable of further foaming by foaming the foamed resin beads, and then the prefoamed particles are molded into a desired shape by re- , And it is often the case that there is a significant difference in the specific gravity between the pre-expanded particles due to the addition of the functional additive or the difference in the expansion ratio.

However, when the pre-expanded beads having different specific gravity are mixed in this manner, the pre-expanded beads having a high specific gravity are settled downward, and even when foam molding is performed in a mold, pre- It is possible to obtain a foamed product having a block shape or a layered shape separated from each other by being localized in a certain region according to the specific gravity without uniformly distributing different kinds of expanded particles having different specific gravity. As described above, unless the composite foamed article is in the form of a homogeneous mixture, there is a problem that it is difficult to obtain an improvement in physical properties to be obtained by mixing different kinds of expanded particles.

Because of such a problem, conventionally, a composite foamed article in which preformed particles obtained from foamable particles having a high specific gravity added with a functional additive as described above are mixed with preformed particles having different specific gravity and heterogeneous foamed particles uniformly mixed And they have been used in the form of a layered product or a block-shaped product by using a foamed molded product in which different kinds of expanded particles are respectively molded.

DISCLOSURE OF THE INVENTION The present invention has been made to solve the problems of the conventional composite foamed articles using the above-mentioned heterogeneous expanded particles, and the advantages of the heterogeneous particles are maximized and the disadvantages of the heterogeneous particles are complemented, Uniform foamed particles of uniformly distributed heterogeneous expanded particles capable of ensuring uniform physical properties and functionalities throughout the formed product and a method for producing the same.

In order to accomplish the above object, the present invention provides a composite foam,

A composite foamed article obtained by fusion bonding two or more kinds of expanded particles,

In the composite foamed molded product, secondary foamed particles of high-boiling pre-expanded beads having a relatively large specific gravity in the state of pre-expanded beads; The secondary expanded particles of the low specific gravity pre-expanded beads having a coating layer for increasing the specific gravity on the surface of the low specific gravity pre-expanded beads having relatively low specific gravity in the state of pre-expanded beads are uniformly mixed.

Preferably, the high-boiling pre-expanded beads are formed by prefoaming a mixture of a functional additive in the inside of the expandable resin particles and / or a low expansion ratio relative to low specific gravity pre-expanded beads, The functional additive may also be incorporated into the coating layer of the low specific gravity prefoamed particles.

The method for producing a composite foamed molded article according to the present invention comprises:

Foamed polymer particles which form heterogeneous pre-expanded beads having different specific gravities in the state of pre-expanded beads are foamed to obtain pre-expanded beads having a relatively high specific gravity and pre-expanded beads having a relatively low specific gravity A foaming step;

A specific gravity adjusting step of forming a coating layer on the surface of the low specific gravity pre-expanded beads to adjust the specific gravity of the low specific gravity pre-expanded beads to an even level capable of forming a uniform mixture with the high specific gravity pre-

A pre-expanded bead mixing step of obtaining a uniform mixture of the high specific gravity pre-expanded beads and the coated low specific gravity pre-expanded beads;

And a composite foam molding step of supplying a uniform mixture of the pre-expanded beads into a mold and performing foam molding.

According to the present invention, it is possible to obtain a composite foamed article in which two or more different kinds of foamable polymer particles designed to have different specific gravities in the state of pre-expanded beads are used for imparting various functions, have.

The resultant composite foamed product exhibits different performances of different kinds of particles, so that the advantages of the two kinds of particles complement each other's disadvantages and can exert an excellent function as a whole. In addition, different foamed particles are uniformly distributed This functionality can be uniformly exerted throughout the composite foam.

For example, high-boiling pre-expanded beads having relatively high specific gravity due to the addition of graphite to the interior due to their excellent heat insulation and low expansion ratio, and general low-density pre-expanded beads having relatively low specific gravity, The coated preformed foamed particles having a specific gravity equal to that of the high specific gravity pre-expanded particles are uniformly mixed to form a coating layer with a functional coating liquid added with a flame retardant on the surface of the high specific gravity pre- It is possible to form a composite foamed article in which the distribution of the expanded particles is uniformly mixed as a whole, and the resulting composite foamed molded article can have excellent heat resistance and flame retardancy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a cross-sectional structure of a composite foamed molded article according to an embodiment of the present invention;
FIGS. 2A and 2B are diagrams schematically showing cross sections of high specific gravity pre-expanded particles and coated low specific gravity pre-expanded particles;
3 is a flowchart showing a process for producing a composite foamed molded article according to the present invention;

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings, in which: FIG.

FIG. 1 is a view schematically showing a cross-sectional structure of a composite foamed molded article according to an embodiment of the present invention. FIGS. 2a and 2b are schematic cross-sectional views of a high specific gravity pre- Fig.

Referring to FIG. 1, the composite foamed product 1 according to the present invention comprises two or more kinds of expanded particles 10 ', 20'.

The foamed particles 10 'and 20' are obtained by foaming the pre-expanded beads 10 and 20 as shown in FIG. 2 obtained by primarily foaming expandable resin particles into a molding die, The surfaces of the secondary expanded particles 10 'and 20' are fused to each other to form a composite foam article 1 in the form of a lump. The expandable resin particle includes a foamed polystyrene-based resin, and a known expandable resin such as a foamed polypropylene-based or expanded polyethylene-based resin.

According to this embodiment, in the composite foamed molded article 1, the secondary expanded particles 10 'of the high specific gravity pre-expanded beads 10 having a relatively large specific gravity in the pre-expanded bead state and the secondary expanded beads 10' The secondary expanded particles 20 'of the coated low specific gravity pre-expanded particles 20 having the coating layer 22 for increasing the specific gravity are formed on the surface of the low specific gravity pre-expanded particles 21 having a relatively low specific gravity, have.

The high specific gravity pre-expanded beads 10 may be formed by foaming expandable particles made of a polymer having a relatively low expansion ratio or having a relatively high density, or may be formed by adding a functional additive 11 that increases the specific gravity inside the expandable particles It may be included, or it may be high by both.

The functional additive 11 that increases the specific gravity is added for imparting specific functionality to the foamed molded product and includes various types of functional additives such as an adiabatic agent, a filler, a reinforcing agent, a colorant, an impact resistance agent, and a flame retardant agent And foamable resins in which various kinds of functional additives are added as well as the above-described conventional techniques for imparting various functions are known.

Among these functional additives, in the case where an inorganic additive having a high specific gravity, no foaming property, or an inorganic additive is contained or a large amount of additive is contained, the volume is increased by the preliminary foaming, Of pre-expanded beads.

In particular, when a heat insulating material is added as a functional additive in order to further improve the performance of a foam such as expanded polystyrene as a heat insulating material, a relatively large amount of a high-boiling inorganic heat insulating material is added in an amount of 1 to 30 wt%. Examples of such a heat insulating material include an airgel such as diatomaceous earth, expanded vermiculite, zeolite, bentonite, perlite, silica airgel, or the like having high thermal conductivity selected from graphite, silver, copper, carbon black, aluminum powder, titanium dioxide, And mixtures of two or more of these.

Further, in order to maximize the shape stability and the heat insulating property, the foamed particles to which the above-mentioned heat insulating substance is added are recommended to have a foam expansion ratio as low as about 30 times, and the specific gravity is higher than that of ordinary foamed polystyrene having a foam expansion ratio of 80 to 90 times.

On the other hand, the low specific gravity pre-expanded particles 21 having a relatively low specific gravity in the state of the pre-expanded particles may be pre-expanded foamed particles made of a polymer having a high expansion ratio or a relatively low density, It may be a pre-expanded bead which does not increase the specific gravity by the functional additive such as not containing the functional additive such as the above, or containing the small amount.

When the low specific gravity pre-expanded beads 21 having a relatively low specific gravity are mixed with the high specific gravity pre-expanded beads 10 as described above, when the pre-expanded beads 10 having high specific gravity are mixed down and molded together It becomes very difficult to obtain a foamed molded article in which different kinds of expanded particles are uniformly dispersed and distributed.

Therefore, in the present invention, the coating layer 22 for increasing the specific gravity is formed on the surface of the low specific gravity pre-expanded beads 21 to have a specific gravity equal to that of the high specific gravity pre-expanded beads 10 to be mixed together. The coated low specific gravity pre-expanded beads 20 in which the coating layer 22 is formed are mixed with the high-boiling pre-expanded beads 10 so that any one kind of the pre-expanded beads is not locally biased and uniformly mixed as a whole And the foamed molded product can be foamed and molded to obtain a foamed product in which the secondary expanded particles are uniformly mixed.

The method of forming the coating layer 22 that increases the specific gravity on the surface of the low specific gravity pre-expanded bead 21 is not particularly limited as long as it does not affect the physical properties and moldability of the low specific gravity pre-expanded bead 21. However, since the pre-expanded beads have already been foamed to a certain degree, the surface of the pre-expanded beads is likely to be eroded by external forces such as chemical substances, heat, and pressure, so that the coating layer 22 is formed by a method that does not cause such problems desirable.

The coating layer 22 may be formed on the surface of the low specific gravity pre-expanded bead 21, which has undergone pre-foaming and aging, such as a solution or emulsion type thermoplastic resin adhesive, a thermosetting resin adhesive, A method of spraying a liquid coating liquid containing an adhesive composed of two or more of these, or adding a low specific gravity prefoamed particle 21 to a coating liquid, mixing the coating liquid with the coating liquid, .

The thermoplastic resin used for the thermoplastic resin-based adhesive should have a softening point of the low specific gravity of the expanded particles 21 and a softening point of the low specific gravity of the thermoplastic resin in order to prevent the lowering of the moldability such as the lowering of the meltability due to the lowering of the foaming power during the foam molding by steam heating. It is preferable to use a resin having a softening point and a melting point lower than the melting point.

In the case of the foamed polystyrene prefoamed particles most commonly used, it is preferable that the vinyl acetate resin be one or more of water, alcohols, esters, ketones, carboxylic acids, aromatic hydrocarbons and halogenated hydrocarbons It is preferable to use a thermoplastic resin solution having a concentration of 3 to 80 wt% in the vinyl acetate resin as a coating solution.

When the coating liquid containing the adhesive is added in an amount of about 0.1 to 30% by weight based on the weight of the low specific gravity prefoamed particles, methylene diphenyl diisocyanate (MDI) or TDI (toluene diisocyanate) Is improved.

Since the adhesive components are basically higher in specific gravity than the pre-expanded beads having a markedly lowered density due to the pre-foaming, the specific gravity of the low specific gravity pre-expanded beads 21 can be increased only by coating them, The thickness of the coating layer 22 may be adjusted in consideration of the specific gravity of the high-boiling pre-expanded beads 10.

However, it is possible to add various additives in addition to the adhesive component. Among the additives, the additive having a high specific gravity may increase the specific gravity of the coating layer and increase the specific gravity of the coated pre-expanded beads, In this case, the thickness of the coating layer may be reduced.

The functional additive 23 having various functionalities including a filler may be used as an additive to improve the functionality of the composite foamed molding. Examples of the additives include a foaming agent, a nucleating agent, a lubricant, an antioxidant, a heat stabilizer, a UV stabilizer, A lubricant, a surfactant, a stabilizer, an excipient, a medicament, a solvent, an antioxidant, an antistatic agent, a plasticizer, a plasticizer, a colorant, an impactor, a flame retardant, an antistatic agent, A hardener, a moisture absorber, a reinforcing agent, a perfume, an antibacterial agent, or the like, or a mixture of two or more thereof may be used.

In particular, flame retardant or nonflammable functional additives are preferred. For example, when a flame retardant is included in the functional additives, a flame retardant partition wall is formed between the expanded particles in the composite foamed article by the coating layer, so that it can have excellent flame retardancy which is difficult to obtain in a conventional foamed article. Can also contribute to the increase of the specific gravity of the low specific gravity pre-expanded beads by the coating.

Examples of the inorganic flame retardant include a type such as expanded graphite that forms a carbonized layer on the surface upon exposure to a fire to block contact with oxygen and a type that acts to block contact with oxygen and an inorganic flame retardant such as aluminum hydroxide, magnesium hydroxide, zinc oxide, A flame retardant of the type that acts to prevent the carbonization layer from collapsing due to a decrease in mass due to oxidation while cooling is suitable is suitable.

When the low specific gravity pre-expanded particles 20 having the coating layer 22 containing the inorganic flame retardant are mixed with the pre-expanded particles 10 having a high specific gravity to form a composite, a low specific gravity pre- The number of the expanded particles 20 is 50% or more of the total number of the pre-expanded beads, so that the expanded particles 20 'of the low specific gravity pre-expanded particles 20 having the coating layer containing the flame retardant at the time of mixing, It is preferable to enclose the expanded particles 10 'of the high-boiling pre-expanded beads 10 so that the flame-retardant partition walls can be formed around the expanded particles of the high-boiling pre-expanded beads.

On the other hand, the coating layer 22 is formed by coating the surface of the low specific gravity pre-expanded beads 21 with a coating solution containing a functional additive such as a flame retardant to thereby obtain a specific gravity equivalent to that of the high specific gravity pre- And the preformed foamed particles can be uniformly mixed to thereby produce a uniform composite foamed molded article. In addition, since the foamed foamed product (1) thus obtained exhibits different performances, The advantages of the particles of the present invention complement each other's disadvantages and can exert excellent functionality as a whole. Further, since different kinds of expanded particles are uniformly distributed throughout the composite foamed molded article 1, such functionality can be exerted uniformly throughout the composite foamed article 1. [

A method for producing a uniform composite foamed article using the above-mentioned different kind of expanded particles will be described with reference to Fig.

First, two or more kinds of foamable polymer particles forming heterogeneous pre-expanded particles having different specific gravities in the state of pre-expanded beads are foamed to obtain relatively high pre-expanded beads 10 and low pre-expanded pre-expanded beads 21 (Pre-foaming step).

The surface of the low specific gravity pre-expanded particles 21 is coated with a coating liquid or the like to form a coating layer 22 to form a coated low specific gravity pre-expanded bead 20. Through this process, the specific gravity of the low specific gravity pre-expanded beads can be adjusted to an even level to be uniformly mixed with the high specific gravity pre-expanded beads (specific gravity adjusting step).

Next, the high specific gravity pre-expanded beads 10 and the coated low specific gravity pre-expanded beads 20 are mixed to obtain a homogeneous mixture in which these pre-expanded beads are uniformly mixed throughout (pre-expanded bead mixing step) .

 Finally, a homogeneous mixture of the pre-expanded beads is fed into a mold and subjected to foam molding to obtain a uniform composite foamed article using heterogeneous expanded particles having desired properties (composite foam molding step).

Example

Hereinafter, the present invention will be described in more detail by way of examples.

Examples 1 to 2

Expanded foamed polystyrene particles ("Neopole", trade name of BASF) having graphite added therein were prefoamed 30 times to prepare prefoamed particles having a high specific gravity (density of 33 kg / m3).

The commercially available expandable polystyrene particles were prefoamed at 90 times to prepare low specific gravity pre-expanded beads having a density of 11.2 kg / m < 3 >.

Aluminum hydroxide was added to the aqueous solution of vinyl acetate to prepare a coating liquid having a solid content of 60%, and this coating liquid was applied to the surface of the low specific gravity prefoamed particles. The coating liquid used was 300% of the weight of the low specific gravity prefoamed particles, and the density of the coated low specific gravity prefoamed particles was measured to be 32 kg / m < 3 >

The high specific gravity pre-expanded beads and the coated low specific gravity pre-expanded beads were mixed at a ratio of 1: 1 (Example 1) and 1: 9 (Example 2), respectively, .

As a result of examining the cross sections of the composite foamed products obtained in Examples 1 and 2, it was found that the composite foamed products obtained in Example 1 had high uniformity of foam distribution and high specific gravity pre- It was in the form of foamed molding.

On the other hand, the composite foam produced in Example 2 had a density of 29.6 kg / m < 3 >, and as a result of thermal insulation test, the thermal conductivity was 0.037 W / mK, which was similar to the thermal conductivity of general expanded polystyrene. Also, as a result of the test of the flame retardant material and the semi-combustible material, it was confirmed that they exhibited excellent flame retardancy and semi-flammability as 3.7 MJ / m 2 and 5.4 MJ / m 2, respectively.

1: Compound foamed molding
10: prefoamed prefoamed particle 11: functional additive
20: Coated low specific gravity prefoamed particle 21: Low specific gravity prefoamed particle
22: Coating layer 23: Functional additive

Claims (11)

A composite foamed molded product obtained by fusion-bonding two or more kinds of heterogeneous expanded particles,
In the composite foamed molding,
A secondary expanded particle of a high specific gravity pre-expanded bead having a relatively large specific gravity in the state of pre-expanded beads;
Characterized in that the secondary expanded particles of the coated low specific gravity pre-expanded particles having a coating layer for increasing the specific gravity on the surface of the low specific gravity pre-expanded particles having relatively low specific gravity in the state of pre-expanded beads are uniformly mixed Composite foamed molding using particles. The composite foamed molded article using the heterogeneous expanded beads according to claim 1, wherein the high-boiling pre-expanded beads are formed by prefoaming a mixture of a functional additive in the inside of the expandable resin beads. 3. The method of claim 2, wherein the functional additive is selected from the group consisting of graphite, silver, copper, carbon black, aluminum powder, titanium dioxide, and zinc, And a porous inorganic material selected from airgel, and a mixture of two or more thereof. The uniformly foamed composite foam according to any one of claims 1 to 3, wherein the functional additive is incorporated in the coating layer of the coated low specific gravity prefoamed particles. 4. The method of claim 2 or 3, wherein the functional additive is incorporated into the coating layer of the coated low specific gravity pre-expanded beads, wherein the functional additive incorporated into the coating layer of the coated low specific gravity pre- A composite foamed article using the heterogeneous expanded particles, characterized by having functionalities different from those of functional additives incorporated therein. The composite foamed molding according to claim 5, wherein the functional additive added to the coating layer is a flame retardant or a nonflammable additive. The composite foamed article according to any one of claims 1 to 3, wherein the high specific gravity pre-expanded particles have a low expansion ratio as compared with the low specific gravity pre-expanded particles. The uniformly foamed composite foam according to claim 7, wherein a functional additive is incorporated in the coating layer of the coated low specific gravity prefoamed particles. The foamed preform according to claim 2 or 3, wherein the high specific gravity pre-expanded bead has a lower expansion ratio than the low specific gravity pre-expanded bead, and the functional additive is incorporated into the coating layer of the coated low specific gravity pre- Characterized in that the functional additive incorporated into the coating layer of the coated low specific gravity pre-expanded particles has a different functionality from the functional additive incorporated into the inside of the high specific gravity pre-expanded beads. The composite foamed article according to claim 9, wherein the functional additive added to the coating layer is a flame retardant or a nonflammable additive. A prefoaming step of foaming at least two kinds of foamable polymer particles forming heterogeneous prefoamed particles having different specific gravities in the state of prefoamed particles to obtain prefoamed particles having relatively high specific gravity and relatively low specific gravity of prefoamed particles ;
A specific gravity adjusting step of forming a coating layer on the surface of the low specific gravity pre-expanded beads to adjust the specific gravity of the low specific gravity pre-expanded beads to an even level capable of forming a uniform mixture with the high specific gravity pre-
A pre-expanded bead mixing step of obtaining a uniform mixture of the high specific gravity pre-expanded beads and the coated low specific gravity pre-expanded beads;
And a composite foam forming step of supplying a uniform mixture of the pre-expanded beads into a molding mold and performing foam molding. The method of producing a composite foamed article using the heterogeneous expanded beads according to claim 1,

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