JP3424500B2 - Aggregate molded body of expanded beads and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collective molding of foam beads having a large number of beads made of a foam having pulp as a skeleton and an adhesive for bonding these beads to each other.
Also, the present invention relates to a method for manufacturing the molded body. More specifically,
INDUSTRIAL APPLICABILITY The present invention can be used as a cushioning material for electric appliances and food packaging, a building material such as a heat insulating material and a soundproofing material, and does not cause waste pollution even if it is incinerated at the time of disposal. Manufacturing technology.

[0002]

2. Description of the Related Art Styrofoam is widely used as a cushioning material for packaging, a building material, etc. because it is inexpensive and has excellent performance. However, when this material is incinerated after use, it generates high heat and damages the furnace, and when it is landfilled, it is not decomposable and bulky, which causes a shortage of treatment sites. Have a

In recent years, interest in environmental problems has increased significantly, and the ease of processing when a product is discarded or the recyclability is becoming an important point in product design. Therefore, the advent of a new material replacing the styrofoam having the above problems is desired.

For these reasons, pulp molds, which are one of recycled products of waste paper, as well as corrugated cardboard and recycled paper, and which can be used as a cushioning material, have been attracting attention.
Pulp mold is manufactured from recycled pulp as a raw material,
By devising the shape, it is possible to impart a buffering force, strength, and the like, and it has the advantage that both incineration and landfill processing are easy.

However, the cushioning strength of the pulp mold is not sufficient and the range of use is limited. In addition, it takes time because it is necessary to create a die having a complicated shape dedicated to the design and manufacture of the cushioning material, and it is difficult to prototype and develop a new shape. Furthermore, it is difficult to apply it to applications other than cushioning materials such as styrofoam, and it has poor moldability, processability, and water resistance.

On the other hand, the present applicant has proposed a pulp foam bead having pulp as a skeleton and a method for producing the same, or a pulp foam cushioning material obtained by adhering the pulp foam beads into a molded body and a method for producing the same. (Japanese Patent Laid-Open No. 05-27
No. 1457, Japanese Patent Laid-Open No. 05-171458, Japanese Patent Laid-Open No. 05
-230269, Japanese Patent Laid-Open No. 06-015753).

The above-mentioned pulp foam beads have a pulp and a biodegradable thickener as a main raw material of a three-dimensional network structure, and have bubbles caused by a decomposable foaming agent or a surfactant inside. The foamed bead of pulp can be used as it is as a cushioning material, or can be used as an aggregate, and has excellent cushioning performance. In addition, for the purpose of molding convenience, etc., a method has also been proposed in which a thermoplastic resin layer is provided on the surface of the pulp foam beads, and heat fusion is performed to produce an aggregate molded body.

[0008]

However, the proposed method for producing an aggregated molded product of pulp expanded beads is required to maintain necessary facilities and operations, or properties such as elasticity and easy incineration of the pulp expanded beads as a raw material. In some respects, there are places where further improvement is desired.

The present invention has been made based on this point of view, and is a method for producing an aggregate molded body of expanded beads, which requires simple equipment and operation and does not impair the characteristics of the raw material beads in the production process. And an aggregate molded body of foam beads produced by the same method.

[0010]

The first aspect of the present invention is as follows.
In the method for producing an aggregate molded body of foam beads, an applying step of applying a coating agent containing a water-soluble adhesive to a large number of beads made of a foam having a pulp skeleton, and after the applying step, a large number of the beads are applied. A filling step of filling the inside of the molding frame, and a watering step of melting the adhesive by pouring steam into the molding frame to add water to the coating agent on the plurality of beads after the filling step, and After the water addition step, by stopping the supply of the water vapor and reducing the pressure inside the molding frame, the beads are dried and the adhesive is solidified, and a drying and adhering step of adhering the plurality of beads together, and It is characterized by having.

A second aspect of the present invention is a method for producing an aggregated molded product of expanded beads, in which a large number of beads made of a foam having pulp as a skeleton are coated with a coating agent containing a heat-melting adhesive. Step, after the applying step, a filling step of filling the large number of beads in a molding frame, and after the filling step, a heating fluid is caused to flow in the molding frame to heat the coating agent on the large number of beads. By
A heating step of melting the adhesive, and after the heating step,
And a step of adhering the plurality of beads to each other by solidifying the adhesive by stopping the supply of the heating fluid.

A third aspect of the present invention is characterized in that, in the method for producing an aggregate molded body of expanded beads of the first or second aspect, the coating agent contains expandable particles. A fourth aspect of the present invention is a method for producing an aggregated molded product of expanded beads, wherein a large number of beads made of a foam having pulp as a skeleton contain a thermoplastic resin, expandable particles and a water-soluble adhesive. An application step of applying a coating agent,
After the coating step, a filling step of filling the large number of beads in a molding frame, and after the filling step, heated steam is caused to flow in the molding frame to heat and hydrate the coating agent on the large number of beads. By heating and watering step of melting the thermoplastic resin and the adhesive and foaming the expandable particles, and after the heating and watering step, the supply of the heated steam and the inside of the molding frame are stopped. The drying and bonding step of drying the beads by reducing the pressure and solidifying the thermoplastic resin and the adhesive to bond the plurality of beads to each other is performed.

According to a fifth aspect of the present invention, in an aggregate molded body of expanded beads, a large number of beads made of a foam having a pulp as a skeleton and an adhesive for adhering the large number of beads are provided. It is characterized by being manufactured by the manufacturing method according to any one of the first to fourth aspects.

[0014]

1 (a) to 1 (d) are views showing the operation of a molding frame 12 in the order of steps in the method of manufacturing an aggregated molded product of foam beads according to an embodiment of the present invention. Figure 1
(A) As illustrated, the molding frame 12 is detachably combined to form a molding space 18, and the female mold 14 and the male mold 1 are joined together.
Have six. The female mold 14 has an inner frame 22 for defining the molding space 18 and an outer frame 24 for supporting the inner frame 22. Between the inner frame 22 and the outer frame 24, a vapor reservoir 26 that faces the molding space 18 via the wall surface of the inner frame 22 is formed. Male 1
6 also has an inner frame 32 for defining the molding space 18 and an outer frame 34 for supporting it. A vapor reservoir 36 that faces the molding space 18 via the wall surface of the inner frame 32 is formed between the inner frame 32 and the outer frame 34.

In order to evacuate the interior of the molding space 18 under reduced pressure, an exhaust passage 28 is formed corresponding to the connecting portion between the female mold 14 and the male mold 16. The exhaust passage 28 communicates with a vacuum exhaust system (not shown) arranged outside the molding frame 12, and also communicates with the molding space 18 through a hole 38 formed in the male mold 16. Hole 3
The inner end portion of 8 is covered with a mesh (not shown) having meshes of such a degree that the pulp foam beads as a raw material do not pass through.

A large number of holes 42 are formed in the inner frames 22, 32 for introducing steam from the steam reservoirs 26, 36 into the molding space 18. The inner end of the hole 42 has a mesh (not shown) whose roughness is such that the pulp foam beads do not pass through.
Covered by. In addition, the steam reservoir 2 is provided from the outside of the molding frame 12.
In order to introduce steam into the inner frames 6 and 36, the outer frames 24 and 34 are formed with a large number of holes 44 having a larger diameter than the holes 42 of the inner frames 22 and 32.

An introduction pipe 46 is connected to the center of the female mold 14 in order to introduce the expanded pulp beads into the molding space 18.
The introduction pipe 46 penetrates the inner frame 22 and the outer frame 24 of the female mold 14 to connect the molding space 18 and the outside of the molding frame 12 to each other.
A shutter 48 that opens and closes the introduction pipe 46 is provided at the inner end of the introduction pipe 46. The shutter 48 is composed of a mesh (not shown) having meshes of such a degree that the pulp foam beads do not pass through.

In order to extrude the molded body after molding from the molding space 18, a plurality of extruding plates 52 are arranged in the molding space 18 so as to surround the inner end portion of the introducing pipe 46. The pushing plate 52 is
The operation bar 5 penetrating the inner frame 22 and the outer frame 24 of the female mold 14.
4 and can be operated from the outside of the molding frame 12.

Next, a method of manufacturing the aggregate molded body of foam beads according to the embodiment of the present invention using the molding frame 12 will be described in order. First, a raw material bead is prepared by applying a coating agent to a large number of expanded beads, that is, a large number of beads made of a foam having pulp as a skeleton. The foam beads may be any foam beads having a skeleton of pulp and appropriately dimensioned. However, in the present embodiment, as described later in detail, Japanese Patent Application Laid-Open No. 05-271
It is assumed that the pulp foam beads disclosed in Japanese Patent Application Laid-Open No. 457 and JP-A No. 05-271458 are used.

The coating agent is used for the first purpose of adhering the expanded beads to each other in the completed molded product of the expanded beads. Therefore, it is essential that the coating agent contains at least an adhesive. From the viewpoint of facilitating the manufacturing process, either one or both of a heat-melting adhesive and a water-soluble adhesive can be used as the adhesive.

The coating agent may further contain expandable particles. In this case, in the molded body after completion,
Since the space between the foam beads is further filled with the foam layer formed by foaming the expandable particles, the cushioning property and the soundproofing property of the molded body are improved. In the case of heat-fusible expandable particles, the expandable particles can also be used as an adhesive.

In the present embodiment, a coating agent containing a thermoplastic resin, expandable particles, and a water-soluble adhesive is used. Here, the expandable particles are composed of microcapsules made of a heat-fusible resin in which a solvent having a low boiling point is enclosed, and have an expansion coefficient of about 50 to 100 times. Note that these materials contained in the coating agent will be described later in detail.

On the other hand, as shown in FIG. 1A, the molding frame 12
The female mold 14 and the male mold 16 are combined to form a molding space 18. At this time, a gap of several mm to several tens of mm may be provided between the female mold 14 and the male mold 16 so that the compressed air escapes better in the next step.

Next, as shown in FIG. 1 (b), a large number of beads B coated with the coating agent as described above are passed through the introducing pipe 46 with the shutter 48 opened, and the molding frame 12 is formed.
The molding space 18 is filled. At this time, the beads B are forcedly sent from the introduction pipe 46 into the molding space 18 using compressed air (see arrow L1), and the exhaust passage 28 and the hole 38 are formed.
The interior of the molding space 18 is evacuated via a vacuum exhaust system (not shown) (see arrow L2). Thereby, the beads B are discharged as the compressed air is discharged through the holes 38 and 42 of the inner frames 22 and 32, the exhaust passage 28, and in some cases, the gap between the female mold 14 and the male mold 16. It is filled so as to extend to every corner of the molding space 18.

After filling a predetermined amount of beads B, as shown in FIG.
(C) As shown in the figure, the supply of compressed air and the operation of exhausting are stopped, and the shutter 48 of the introduction pipe 46 is closed. If a gap is left between the female mold 14 and the male mold 16, this is completely closed. Then, from the holes 44 of the outer frames 24, 34 to the holes 4 of the vapor reservoirs 26, 36 and the inner frames 22, 32.
Heated steam is caused to flow into the molding space 18 through 2 (see arrows L3 and L4).

When the coating agent applied to the beads B is heated by the heated steam, the thermoplastic resin and the microcapsules of expandable particles contained therein are melted. For this reason, the low boiling point solvent enclosed in the microcapsules undergoes rapid expansion, and the gap between the beads B is somewhat widened and the gap between the beads B is filled. Further, when the heated steam condenses on the beads B, the water-soluble adhesive in the coating agent is watered, and this starts melting. Since the bead B has already been foamed, it does not foam itself in this step.

After flowing the heated steam for a predetermined time, for example, 1 to 2 minutes, as shown in FIG. 1D, the supply of the heated steam is stopped and the molding space is formed through the exhaust passage 28 and the hole 38. The inside of 18 is evacuated by a vacuum exhaust system (not shown) (see arrow L5). In the initial stage of this process, the temperature inside the molding space 18 is lowered with the stop of the supply of the heated steam, so that the condensation or condensation of the steam is further promoted. Therefore, the water-soluble adhesive in the coating agent is hydrolyzed and melted, and wraps around between the beads B and between the beads B and the foam layer F formed by foaming of the expandable particles (see FIG. 2). .

However, when the pressure inside the molding space 18 is reduced to below atmospheric pressure by evacuation, the boiling point of water lowers, so that the water in the molding space 18 evaporates. Therefore, the water-soluble adhesive is hardened and becomes the adhesive layer A for adhering the beads B to each other or the beads B and the foamed layer F. Further, at this time, the residual water in the molding space 18 and the excess water that has permeated the body of the beads B are also evaporated, and the beads B are dried. Removal of water by depressurization
For example, for the supply of heated steam for 1 to 2 minutes, the reduced pressure for about 30 seconds is sufficient.

Further, when the temperature in the molding space 18 is sufficiently lowered, the thermoplastic resin in the coating agent is also hardened, and together with the water-soluble adhesive, the beads B or the adhesive layer for adhering the beads B and the foam layer F together. Form A. If molding space 1
If the temperature decrease in 8 is insufficient, the supply system used to introduce the beads B from the introduction pipe 46 is used as it is, and the compressed air at room temperature is sent to the molding space 18, Cooling can be promoted.

In this way, the structure shown in FIG.
The gap between the beads B is filled with the foam layer F, and the beads B
An aggregate molded body of foam beads having excellent cushioning properties and soundproofing, which has a structure in which the beads B and the foam layer F are bonded to each other by the adhesive layer A, is completed. After completion, female mold 14 and male mold 1
The molded body can be taken out from the female mold 14 by separating 6 and projecting the extruding plate 52 via the operation bar 54.

The foamed bead aggregate molding according to the present invention can be manufactured even when the coating agent applied to the beads B does not contain expandable particles and is composed only of an adhesive. In this case, in the completed molded body of the expanded beads, as shown in FIG.
Therefore, it has a structure in which it is almost point-bonded.

When only a heat-melting adhesive is used as the adhesive to be added to the coating agent applied to the beads B, dry heated gas, for example, hot air, is flowed into the molding space 18 instead of the heated steam. be able to. in this case,
Since the beads B and the coating agent can be heated without water, the reduced pressure drying step shown in FIG. 1D is not necessary. However, there is a problem that hot air is far inferior to the heated steam in terms of thermal conductivity. According to the experiment, the heating process time is 1 to 1 when heated steam is used.
2 minutes was sufficient, while 4 with hot air
It took 0-50 minutes.

Next, the raw materials used in the method for producing the aggregated molded body of expanded beads according to the present invention will be described. As described above, the pulp foam beads used in the above-mentioned embodiment are disclosed in Japanese Patent Laid-Open Nos. 05-271457 and 05-27.
It is disclosed in Japanese Patent No. 1458. That is, the pulp expanded beads are produced as expanded beads containing pulp containing recycled pulp and a biodegradable thickener as main raw materials of a three-dimensional network structure, and containing bubbles due to the decomposition type foaming agent inside. It

Pulp containing recycled pulp, which constitutes the expanded beads of pulp, includes bleached or unbleached kraft pulp, soda pulp, groundwood pulp, sulfite pulp, thermomechanical pulp, etc. made from softwood or hardwood, and recycled paper. , Recycled corrugated paper, recycled pulp derived from old magazines, etc. can be used alone or in combination of two or more. There is no problem if the residual components such as the binder contained in the waste paper are small. Further, cotton-like pulp or the like produced in a process such as paper processing can also be used.

An appropriate amount of solvent is added to the pulp containing the recycled pulp, and the mixture is suspended and kneaded. As a solvent,
Although not particularly limited, the raw material is selected so as not to be affected by aggregation or the like. Specific examples thereof include water and alcohols such as ethyl alcohol, which may be mixed and used.

Next, a biodegradable thickener is added to this and mixed. The amount to be added may be changed according to the conditions such as the added substance or the strength of the aggregated molded product of the expanded beads after completion. As this biodegradable thickener, sodium alginate, natural polysaccharides such as starch, agar and mannan, processed products of natural polysaccharides such as carboxymethyl cellulose, or synthetic water-soluble polymers such as polyvinyl alcohol can be used. Is.

In order to make this into pulp expanded beads, 2
There are two ways. One is a method in which a foaming agent is added, and the mixture is molded into particles and then foamed. The other is a method in which a surfactant is added to cause foaming, and then it is formed into particles.

When a foaming agent is added, an appropriate amount is added depending on the required strength of the pulp foam beads. As the foaming agent, specifically, a heat decomposition type foaming agent is preferably used. After being formed into particles of an appropriate size, it is heated to foam. As such a foaming agent, for example, an inorganic foaming agent such as sodium bicarbonate or ammonium carbonate, an organic foaming agent such as azodicarbonamide, benzenesulfonylhydrazide, or the like can be used.

Also, when a surfactant is added, an appropriate amount is selected and added depending on the required strength of the expanded pulp beads. Specifically, nonionic surfactants such as soap (higher fatty acid salt), Tween (trade name of Kanto Chemical Co., Ltd.) type and span (trade name of Kanto Chemical Co., Ltd.) type fatty acid ester, etc. An amphoteric surfactant, an anionic surfactant such as a sulfonated compound, a cationic surfactant, etc. can be used. These and the above-mentioned mixture are vigorously stirred to form bubbles. The rate of foaming due to stirring can be adjusted as desired. The foamed beads are obtained by molding the raw material containing the air bubbles into granules and heating and drying.

As described above, the coating agent applied to the pulp expanded beads in the first step of the method for producing the aggregated molded product of expanded beads according to the above-described embodiment is the thermoplastic resin, the expandable particles, and the water-soluble adhesive. Including and

As the expandable particles contained in this coating agent, heat-expandable microcapsules in which a solvent having a low boiling point is enclosed in heat-fusible microcapsules can be used. That is, the polymer of the outer shell is softened by heating and the solvent inside is gasified to expand the volume several tens of times.

Concretely, as the internal solvent, an organic solvent such as isoptane, pentane, petroleum ether, hexane, etc. is wrapped with a thermoplastic resin made of vinylidene chloride, acrylonitrile, acrylic acid ester, methacrylic acid ester or the like. Expandable microcapsules can be preferably used.

As the thermoplastic resin contained in the coating agent, polyethylene resin, polyester resin, polyacrylic ester, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, acrylic resin, polyamide such as polyvinylidene chloride and nylon, Examples thereof include polyvinylpyrrolidone and the like, or copolymers thereof, such as vinyl acetate-polyethylene copolymer and polyethylene-acrylic acid copolymer. The thermoplastic resin is prepared by using these materials alone or in combination.

As the water-soluble adhesive contained in the coating agent, a processed cellulose product such as carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, a compound such as polyvinyl alcohol or polyvinyl pyrrolidone, or a natural product such as starch. Adhesives based on can be used.

The coating agent containing a thermoplastic resin, expandable particles, and a water-soluble adhesive can be used as an emulsion obtained by dissolving the thermoplastic resin and the water-soluble adhesive in an appropriate solvent.
It can be prepared by mixing expandable particles. Further, the coating agent can be applied to the surface of the foamed bead beads by a method such as spray coating or impregnation. Alternatively, a powdered thermoplastic resin or a water-soluble adhesive may be used as a dispersion, and the expandable particles may be mixed with the dispersion to apply the dispersion by spraying or the like.

The amount of the thermoplastic resin, the expandable particles, the water-soluble adhesive, etc. contained in the coating agent depends on the adhesive strength required for the aggregated molded product of the expanded beads and the expanded expandable particles. It can be appropriately selected depending on the conditions such as the added elasticity and the buffering property. After the coating agent is applied, the expanded pulp beads are dried at an appropriate temperature to evaporate the solvent, whereby a dried coating agent layer can be formed on the surface of the expanded pulp beads.

[0047]

EFFECTS OF THE INVENTION According to the present invention, the adhesive and the coating agent containing the expandable particles as the case requires are applied to the foam beads, and the beads are treated in the molding frame. The equipment and operations required to manufacture the body are simplified. In particular, when a water-soluble adhesive is used as the adhesive in the coating agent, heating steam is caused to flow in the molding frame for processing, and then the drying process is performed by depressurizing the molding frame. Not only is the operation simple, but the characteristics of the raw material beads are not impaired during the manufacturing process. Also, when expandable particles are put in the coating agent, the space between the expanded beads can be filled with the expanded layer,
It becomes possible to improve the cushioning property and the soundproofing property of the molded body.

[Brief description of drawings]

FIG. 1A to FIG. 1D are diagrams showing, in the order of steps, the operation of a molding frame in the method of manufacturing an aggregated molded body of expanded beads according to an embodiment of the present invention.

FIG. 2 is a schematic view showing the internal structure of an aggregated molded body of expanded beads produced by the method shown in FIG.

FIG. 3 is a schematic diagram showing an internal structure of an aggregate molded body of expanded beads produced by a modification of the method shown in FIG.

[Explanation of symbols]

12 ... Molding frame 14 ... Female 16 ... Male 18 ... Molding space 26, 36 ... Vapor reservoir 28 ... Exhaust path 38, 42, 44 ... holes 46 ... Introduction tube 48 ... Shutter 52 ... Extruded plate 54 ... Operation bar A ... Adhesive layer B ... Beads F ... Foam layer

Continued Front Page (72) Inventor Tadashi Hongo 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (56) Reference JP-A-6-15753 (JP, A) JP-A-10-265607 ( JP, A) JP-A-10-138273 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9/236 B29C 67/20

Claims (5)

(57) [Claims] 1. A coating step of coating a coating agent containing a water-soluble adhesive on a large number of beads made of a foam having a pulp skeleton, and after the coating step, a molding frame is filled with the large number of beads. A filling step, and a watering step of melting the adhesive by pouring water vapor into the molding frame to water the coating agent on the plurality of beads after the filling step, and the water vapor after the watering step. And a step of drying and adhering the plurality of beads by adhering the adhesive to each other by drying the beads and solidifying the adhesive by stopping the supply of the mixture and depressurizing the molding frame. A method for producing an aggregate molded body of foam beads. 2. An applying step of applying a coating agent containing a heat-melting adhesive to a large number of beads made of a foam having pulp as a skeleton, and a molding frame is filled with the large number of beads after the applying step. And a filling step after the filling step, by heating the coating agent on the large number of beads by flowing a heating fluid in the molding frame, to heat the adhesive, after the heating step, And a step of adhering the large number of beads to each other by solidifying the adhesive by stopping the supply of the heating fluid. 3. The method for producing an aggregate molded body of expanded beads according to claim 1, wherein the coating agent contains expandable particles. 4. An applying step of applying a coating agent containing a thermoplastic resin, expandable particles and a water-soluble adhesive to a large number of beads made of a foam having pulp as a skeleton, and after the applying step, A filling step of filling a large number of beads in a molding frame, and after the filling step, heating steam is caused to flow in the molding frame to heat and water the coating agent on the large number of beads, whereby the heat A heating and watering step of melting the plastic resin and the adhesive and foaming the expandable particles, and after the heating and watering step, by stopping the supply of the heated steam and reducing the pressure in the molding frame, A step of drying and adhering the plurality of beads to each other by drying the beads and solidifying the thermoplastic resin and the adhesive. Method of manufacturing a set molded body of foam beads. 5. The method according to claim 1, comprising a large number of beads made of a foam having pulp as a skeleton and an adhesive for adhering the large number of beads to each other. An aggregate molded body of foam beads characterized in that