JP3009261B2 - Moisture-proof starch molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a molded product mainly composed of starch,
More particularly, the present invention relates to a moisture-proof coated starch molded product having excellent moldability, particularly useful in the field of packaging materials.

[0002] Starch is abundant as a natural polymer substance, but has poor coating properties, lacks water resistance, and has high chemical resistance,
There are problems such as inferior physicochemical properties such as mechanical strength. In fields other than foods, they are only slightly used as oblate, fractionated amylose membrane, medical capsule and the like.

[0003] On the other hand, synthetic resins made from petroleum, which is a finite resource, and packaging materials, which are consumables made of paper pulp that are squeezing forest resources due to rapid consumption rather than reproduction, are basically made of artificial cultivation. Conversion to resources is necessary.

[0004] Further, the waste treatment of synthetic resin causes an environmental pollution problem. In particular, the waste treatment of plastic products in the field of packaging and distribution is an important task at present, but the technical problem of waste treatment is high. At present, the issues are overwhelming and are far from being solved. For example, there is no concrete progress in the separation and recycling of urban garbage and the recycling of resources, there are many environmental problems in incineration, and it is difficult to mass-process plastic photolysis and biodegradation. .

Accordingly, the present inventors have focused on starch which can be mass-produced at low cost as a crop and can be directly used in fertilizers and feeds after use. If a starch product that has various physical properties that can be molded and used like a product and can be mass-produced with current synthetic resin molding and processing equipment without using special equipment is obtained, From the viewpoint that the above-mentioned problems can be solved at a glance, diligent studies have been made on the development of starch products meeting such a purpose.

As a result, this time, a solid filler, water and the like were blended with the starch, and the mixture was heated and dissolved to form a gelatinized composition. The gelatinized composition was formed into a film, for example, and its surface was modified. After that, the moisture-proof starch molded product obtained by bonding the moisture-proof coating layer to the surface of the molded product as a core layer can be molded like a synthetic resin molded product, and can be formed in the same manner as a synthetic resin or paper pulp packaging material. The inventors have found that they can be used, and that they can be used as fertilizers, feeds, etc. after use by pulverization, and have completed the present invention.

Thus, according to the present invention, at least the surface of a gelatinized composition containing starch, an incompatible solid filler and water as a basic composition having a water content of 1 to 20% by weight is modified. The present invention provides a moisture-proof starch molded article comprising a core layer and a moisture-proof coating layer bonded to the surface of the core layer.

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

Core layer : The starch which is the main component of the core layer of the molded product of the present invention is, for example, potatoes such as potatoes; cereals such as corn, rice and wheat; and other starch-containing plant materials such as tapioca. Any of the usual starches issued can be used. In addition, dextrin, acid-treated starch, oxidized starch, cross-linked starch, starch ester, starch ether, graft copolymer, α-starch, fractionated amylose, wet heat-treated starch, etc., also known as modified starch, may be used as starch. [For “processed starch”, refer to “Starch Science Handbook”
(Asakura Shoten issued November 1, 1989) 496-5
See section “23. Modified Starch” on page 22], since processed starch is more expensive than unprocessed starch, it is not very practical to use the modified starch alone in practice. Is preferably used in combination with raw starch. The mixing ratio of the modified starch to the unmodified starch when used in combination can vary over a wide range depending on the use of the molded product, the type of the starch and / or the modified starch, etc., but in general, the amount is 100 parts by weight of the starch. 50 parts by weight or less, preferably 30 parts by weight or less.

[0010] Further, for the purpose of enhancing the mechanical strength of the core layer by promoting fusion adhesiveness with a filler and water retention, the starch may contain other natural polymer substances such as gum arabic. , Natural rubber such as crystal rubber; cellulose derivatives such as carboxymethylcellulose and acetylcellulose; chitin, casein, gluten, collagen,
Animal or plant high molecular substances such as glue, gelatin, etc., or hydrophilic synthetic high molecular substances, for example, water-soluble nylons such as polyvinyl acetate, polyvinyl alcohol, 2-nylon; aliphatic polyesters such as polycaprolactone; polyvinyl methyl ether and the like And the like can also be appropriately compounded. The amount is not strictly limited,
In general, the amount of starch is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less, based on 100 parts by weight of starch (when raw starch and processed powder are used in combination, the same applies hereinafter).

On the other hand, the immiscible solid filler constituting a part of the core layer is a solid substance that does not melt under the molding conditions of the molded article or does not dissolve in the starch melt. It is preferable that the surface has affinity for starch or is subjected to affinity treatment. The shape is not particularly limited and can be freely selected depending on the use of the molded product and the like. For example, it can be in the form of powder, granules, flakes, short fibers, narrow tapes, or the like. . Specifically, for example, an inorganic or organic solid powder having an average particle diameter of 100 μm or less, preferably 1 to 30 μm, for example, calcium carbonate, talc, clay, silica, alumina, glass powder, slag, metal (eg, : Stainless steel, aluminum, copper, iron) powder, wood flour, dry powder of plant foliage, thermosetting resin powder, etc .; the average particle diameter is 100 μm or less, preferably 3 to 50 μm and the aspect ratio is 10 or more flaky solid fine materials, such as mica, stainless steel pieces and the like; fiber length 10 mm or less, preferably 3 mm or less, and fiber diameter 100 μm or less, preferably 3
Short fibers of 0 μm or less, for example, glass fiber, carbon fiber, asbestos, wollastonite, slag fiber, magnesium sulfate fiber, cellulose fiber, cotton, hemp, various synthetic fibers, etc., each of which may be used alone Or a combination of two or more.

The amount of these solid fillers is not strict, and can be varied according to the purpose of use of the molded product, the type of the fillers, and the like. Parts, preferably from 15 to 80 parts by weight, more preferably from 20 to 50 parts by weight. The rigidity of the core layer, mechanical strength, uniform mixing and dispersion of additives, etc. are controlled by the addition of a solid filler. Can be enhanced.

Further, the core layer is used in an amount of 1 to 20% by weight, preferably 5 to 16% by weight, more preferably 8 to 13% by weight, based on 100% by weight of the whole starch composition, in order to maintain the impact resistance of the formed starch. It is important to keep the water content in the range of weight percent. The moisture content of the core layer can be measured by using a Shimadzu electronic moisture meter EB-330MOC according to the heating and drying weight method (weight fluctuation width monitoring method).

[0014] The starch in the core layer may be modified for the purpose of improving the mechanical strength of the core layer, improving the water retention, and facilitating surface treatment. The modification may be either thermal modification or chemical modification, or a combination of both. Thermal denaturation may occur spontaneously depending on the heating conditions used when heat-gelatinizing a mixture of starch and water when forming the molded article of the present invention. ° to about 250 ° C,
In particular, it is preferable to perform the heating by heating at a temperature of about 160 ° to about 220 ° C. for about 3 to about 15 minutes. On the other hand, chemical modification can be achieved by preliminarily compounding a chemical modifier in a starch composition for forming a core layer. The chemical modifier includes a substance capable of undergoing a crosslinking reaction or graft polymerization at a hydroxyl group or a depolymerization break point in starch, and specifically includes a vinyl monomer, a crosslinkable polyfunctional compound, etc. (the surface of the core starch layer described below). Can be used in a small amount of 3% by weight or less, preferably 0.5% by weight or less of the total 100% by weight of the starch composition, and the degree of chemical modification is small. Modification with a low degree of substitution, that is, modification of the starch in the core layer, is mainly performed by thermal modification such as thermal decomposition, dextrinization, and gelatinization.

Further, a surfactant (eg, a nonionic surfactant such as a fatty acid alkanolamide, a fatty acid monoglyceroid, a polyethylene glycol fatty acid ester, etc.), a humectant (eg, polyethylene glycol) may be added to the core layer. Glycerin, polyhydric alcohols such as polyvinyl alcohol, etc.), lubricants (eg, fatty acid amides, fatty acid metal salts, polyethylene wax, etc.), ultraviolet absorbers, antioxidants, coloring agents, and the like.

The molded article of the present invention may be in a state in which the core layer is foamed. For this purpose, a foaming agent may be added to the core layer in advance. The foaming agent may be any of a heat evaporation type and a thermal decomposition type. Specific examples of the heat evaporation type include alcohols such as water (containing water), ethanol, propanol and cyclohexanol; ethyl acetate. Esters such as dioxane; azo compounds such as azodicarbonamide; nitroso compounds such as N, N'-dinitrosopentamethylenetetramine; and benzenesulfonyl hydrazide. Such sulfonyl hydrazide compounds; sodium bicarbonate, ammonium carbonate and the like. The amount of these foaming agents depends on the degree of foaming desired in the core layer, but is usually 5 parts by weight or less, particularly 2 parts by weight or less based on 100 parts by weight of the total amount of starch and solid filler. .

The degree of foaming of the core layer is not particularly limited and can be varied over a wide range depending on the use of the molded product. Generally, the foaming ratio is 3 times or less for a hard plate and 10 times for a sheet. It can be set as a standard, for example, at most 10 times, and at least 10 times with a buffer material.

The core layer of the molded article of the present invention has at least its surface modified in order to enhance the bonding property with the moisture-proof coating layer adhered on the surface. Modification of the surface of the core layer may be any of physical modification and chemical modification,
A combination of both may be used. The physical modification of the former includes flame treatment, rapid heating treatment, sand blast treatment, corona discharge treatment, ultraviolet / α / infrared irradiation treatment, etc. of the surface of the molded core layer. it can.

The latter chemical modification is a particularly preferred treatment,
Chemical modifiers that can be used include substances that change the starch surface into resin by a substitution / crosslinking reaction or graft polymerization at the hydroxyl group or depolymerization break point of the starch on the surface of the core layer,
Specifically, crosslinkable polyfunctional compounds such as maleic acid, phthalic acid, acrylic acid, methacrylic acid, oleic acid, acetic acid and their anhydrides and esters; acrylic acid, acrylonitrile, acrylamide, olefin, styrene, acetic acid Graft polymerized vinyl monomers such as vinyl and the like, and organic peracids [dicumyl peroxide, 2, 2,
5-di-methyl-2,5-di (t-butylperoxy)
Hexane etc.]. Cyclic monomers such as various epoxies, imines and lactams; hydroxyalkyl ethers, diisocyanates,
Formaldehyde and the like and acids can be used for substitution reaction modification and reaction activity.

The treatment with a chemical modifier is carried out, for example, by coating or impregnating the surface of starch, after the modification reaction, by laminating a moisture-proof layer or a moisture-proof layer, and by post-modification reaction, or by mixing with an adhesive layer to modify the laminated layer. For example, modified joining can be performed by lamination extrusion.

The purpose of the modification of the surface of the core layer is to convert the resin into a resin and strongly bond the moisture-proof layer, and the test standard that can most appropriately grasp this is "7.5 heat sealing" of JIS "Food packaging plastic film Z1707". Strength "kg / 1
5 mm width (peeling strength), the degree of denaturation of the core-surface is the peeling strength of the moisture-proof layer = heat sealing strength 0.1 kg / 15
mm or more, preferably 0.2 kg / 15 mm or more. The degree of substitution is also used, and DS = 2 or more [see the above-mentioned “Starch degree” in the lower column of the starch handbooks p497 to p498].

In addition to the chemical or physical modification described above, the surface of the starch in the core layer becomes resinous and the substitution progresses, and the JIS “Moisture Permeability Test Method Z0208 for Moisture Proof Materials” (the following moisture permeability values are based on this test method) moisture permeability of 50g / m ² · 24 ^h
In the following cases, there is no need to bond the moisture-proof layer, and the starch molded product itself becomes moisture-proof and can be a product of the present invention.

Moisture-proof coating layer : The moisture-proof coating layer to be bonded on the core layer according to the present invention is for keeping moisture contained in the core layer so as not to escape from the core layer for a long period of time, and has a moisture permeability ( A continuous thin film having low moisture permeability and a certain degree of flexibility is preferably used. Moisture permeability of the thin film (at 25 μm)
In general, 100g / m ² is / 24hr · 40 ℃ · 90RH
Hereinafter, especially ^{50g / m 2 / 24hr · 40} ℃ · 90RH
Or less, more particularly ^{30g / m 2 / 24hr · 40} ℃ · 9
It is desirable that it be 0 RH or less.

Materials for forming such a moisture-proof thin film include, for example, polyolefin-based resins (eg, polyethylene, polypropylene, etc.), polyester-based resins (eg, polyethylene terephthalate, polybutylene terephthalate, etc.), and vinyl-based resins. Thermoplastic resins such as resins (eg, polyvinyl chloride, polyvinylidene chloride, etc.); fluororesins, silicone resins, paraffins; metals such as aluminum, ceramics and the like.

Among the above, the resins can be applied on the core layer by a method of bonding a preformed film, a coating method, an extrusion lamination method, or the like. The metal can be applied by a vapor deposition method, and the ceramic can be applied by a sol-gel method or the like.

When the resin film is applied to the core layer, the adhesion to the surface of the core layer can be carried out by heat fusion. Alternatively, the resin film may be bonded via an adhesive. Examples of adhesives that can be used include, for example, ethylene-
Elastoplastics such as vinyl acetate resin adhesives, modified olefin resin adhesives, and urethane elastomers are exemplified.

The thickness of the moisture-proof coating layer is not particularly limited as long as it is at least a barrier layer for permeation of moisture, but is generally at least 25 μm or more, preferably 3 μm or more.
The range of 0 to 200 μm, particularly preferably 30 to 60 μm, is suitable. When the thickness is large, it not only serves as a moisture-proof layer but also serves to increase the strength of a molded product.

As described above, since the moisture-proof coating layer serves as a barrier layer for maintaining the water content of the core layer, it is desirable to cover substantially the entire surface of the core layer. In this case, it is desirable that at least both surfaces are covered with a moisture-proof coating layer.

The form of the molded article of the present invention is not particularly limited, and can take various forms according to the application and the like. For example, it takes the form of a round bar square shaped article, an injection molded article, a cushioning material and the like. Can be, but often sheet-like.

The molded product of the present invention can be produced by a method known per se suitable for the form. Hereinafter, the production method will be described more specifically, focusing on a suitable sheet-like molded product. .

The sheet-like molded product of the present invention basically comprises
For example, the starch, the incompatible solid filler and other optional components (modifying agent, foaming agent,
Other additives) are mixed with water, heated to form a gelatinized composition, formed into a sheet, and dried to reduce the water content to 1
After modifying the surface of the moldings to adjust to within the range of ~ 20% by weight, applying a moisture-proof coating layer, with or without an adhesive, and foaming the core layer if necessary Can be manufactured.

First, the components of the core layer can be mixed using an ordinary mixer, blender, tumbler, or the like, and in some cases, can be granulated by heating and mixing.

The starch composition thus mixed and prepared can be heated and melted and melted and homogenously mixed and dispersed in a mixer by a closed pressurizing device, and formed into a film by a gear pump or the like. It is preferable to form a film by melting and dispersing by heating and kneading in a substantially closed state using an extruder. It is preferable that the injection machine also employs an in-line screw and has an extrusion function.

Mixing, extrusion film formation, injection molding and processing of the starch composition can be carried out using general-purpose thermoplastic synthetic resin machinery and methods.

Extrusion film formation can be performed by either low-temperature extrusion or high-temperature extrusion as described below.

Low-temperature extrusion : Many starches and hydrophilic resins are often melted and melted at 100 ° C. or lower due to the presence of water. It can be a starch composition film for a layer.

Depending on the composition of the components of the core layer, it may be necessary to melt and melt the extruder at a maximum temperature of about 140 ° C. In this case, a stirrer mixer or a single tube is provided for cooling and the die is cooled and temperature-controlled. When extruded at 95 ° C. or less, a film without foaming can be obtained.

When extruded from an extruder at 90 ° C. or higher, the discharged film may foam due to rapid evaporation of water. However, a die former direct roll, a sizing die that circulates cooling water near the T-die discharge port. For example, when contacting a cooling metal surface or extruding into a cooling water tank, spraying water, or cooling with an air knife, the discharged film becomes non-foamed.

If further high-temperature treatment is required, a tandem system in which a high-temperature heat-melting extruder and a cooling temperature-controlling extruder are directly connected can be used, whereby sufficient melt-kneading and extrusion at 90 ° C. or less can be performed. It becomes possible. In this case, it is also possible to use a twin screw extruder.

High-temperature extrusion : The extrusion of a starch composition containing water at 100 ° C. or higher foams. In the case of laminating extrusion, when a starch composition is used for the core layer and a moisture-proof resin such as an olefin resin is used for the outer layer, the melting temperature of the resin is high, and the modified layer on the surface of the core layer is also high in temperature, so that molding can be performed. The body will generally be a foam. Such foams are particularly useful, for example, as cushioning materials.
The production of expandable beads is also obtained by high-temperature lamination extrusion cutting and quenching.

The film formed product obtained as described above is dried to adjust the water content to obtain the required water content. When the amount of moisture in the molded product is large, it is desirable to perform drying using a drying furnace or a drying drum. However, when the amount of moisture is relatively small, hot air or the like is blown for a short time after film formation. The required moisture content can be determined by the degree.

According to the present invention, a moisture-proof coating layer is provided on the surface of a core layer mainly composed of a starch and an incompatible solid filler formed as described above. This moisture-proof coating layer,
While keeping the water content in the core layer almost constant, it prevents the components of the core layer from evaporating and leaching to the outside, and further prevents the penetration of moisture, bacteria and other substances from the outside. Thus, the molded article of the present invention can be used in the same manner as a synthetic resin molded article.

When the moisture-proof coating layer is provided on the surface of the core layer formed as described above, the surface of the core layer mainly composed of starch generally has poor affinity with the above-mentioned materials constituting the moisture-proof coating layer. It is often the case that bonding is not performed with sufficient strength if it is applied directly or melt-laminated. Therefore, it is necessary to modify the surface of the core layer in order to improve the bonding property.

The modification of the surface of the core layer can be achieved by, for example, applying a chemical modifier as described above and heating and / or performing a physical treatment to thermally decompose and / or degrade the starch on the surface of the core layer. Alternatively, the adhesion and affinity with the moisture-proof coating layer can be increased by reaction modification with a modifier.

The bonding of the moisture-proof coating layer to the core layer surface thus modified can be performed, for example, as follows.

The physical modification of the starch surface of the core layer starch by corona discharge or the like, or without modification, is carried out by dispersing and applying a chemical denaturant in a lower alcohol, and drying the alcohol.
Heat in a heating furnace of 80 ° to 220 °, or heat only the surface to 200 ° C or more by flame treatment, rapid high-temperature heating,
A method in which a chemical denaturant reacts to modify the starch surface as required, laminates a moisture-proof film and joins by heating under pressure; b. A method of joining; a method of providing an adhesive layer in (a) and (b).

As a method of incorporating a chemical modifier into the adhesive layer, an adhesive layer is applied and laminated on a moisture-proof film or on the surface of a core starch layer at a temperature at which a decomposition reaction does not occur. Method of joining by pressing and heating as a layer / moistureproof layer,
Using a three-layer, five-layer laminating extruder, a starch layer was used as the core layer, a moisture-proof layer was used as the skin layer, and an adhesive layer containing a chemical modifier was used as the intermediate layer.
A method in which all layers are integrally joined by extruding at 60 ° to 220 ° is exemplified.

In the above-mentioned sheet-like molded product of the present invention, the water content of the starch in the core layer is 12% by weight or more, preferably 14% by weight.
As described above, vacuum / pressure forming can be performed.

The expandable beads are extruded in a linear form of 10 mm or less in a three-layer configuration using, for example, a three-type five-layer extruder. If the outlet is not in contact with water and water is sprayed on the discharged material to prevent foaming expansion, it can be manufactured by forming non-foamed or microfoamed pellets covered with a moisture-proof film.

The production of the sheet-shaped molded product of the present invention will be described more specifically with reference to the accompanying drawings.

FIG. 1 is a flowchart in the case of manufacturing a sheet-like molded product using an endless belt capable of performing a heat treatment in a substantially closed state. In this figure, a low-temperature extruded film (1--) of a starch composition produced through an extruder (2), a T-die (3) and a cooling device (4) in a usual manner.
a) is adjusted to a required moisture content by a drying device (5), taken off by a nip roll (6), and a chemical modifier is applied by a modifier coating device (7). The coating agent is dried in a drying oven (8), and physical modification is performed before and after the coating agent if necessary. A moisture-proof film (b) fed through a moisture-proof film feeding device (9), an adhesive layer coater (10), an expander roll (11), etc., is simultaneously fed between the endless belts (12) while being laminated on both sides, and a belt-supporting heating roll In (13), heat compression is performed, and heat treatment and cooling are performed in a substantially closed state.

The endless belt (12) is tensioned by a tension roll (14) and the belt is maintained by a heating roll (16) while maintaining the belt gap.
In step 5), heating treatment is performed as necessary to carry out a denaturation treatment, and the starch molded product (1-
b).

This molded product (1-b) is cooled by a cooling roll (1).
7), a cooling device (19) and a belt supporting cooling roll (2)
0) to 70 ° C. or lower and a non-foaming moisture-proof starch molded product (1-c)
Or a cooling roll (17) and a gap roll (1)
Between 8), the desired belt gap is expanded and foamed, and the temperature is set to 80 ° C. or less by the cooling device (19) and the belt cooling roll (20) to obtain a foamed moisture-proof starch molded product (1-c).

FIG. 2 is a flow sheet of a system for performing a heat treatment in an open state, which is produced through an extruder (2), a T-die (3) and a cooling device (4) by a usual method. The low-temperature extruded membrane (1-a) of the starch composition was adjusted to the required moisture content in a drying oven (5), and nip rolls (6) were prepared.
And the modifier is applied by the modifier applying device (7). Physical denaturation is performed before and after this as necessary.

The adhesive layer and the moisture-proof layer are laminated by the adhesive coater (8) and the moisture-proof coater (9), respectively, and sent to the heating furnace (10).

Then, a moisture-proof starch molded product (1-b) in which the adhesive layer and the moisture-proof layer are fused and bonded by a decomposition reaction modification is cooled by a cooling roll (12) and a cooling device (13) to obtain a final moisture-proof product. A starch molded product (1-c) can be obtained.

In the moisture-proof starch molded product provided by the present invention, a thick sheet-like material is used as a paperboard for boxes, cardboards, and the like. The film can be used for containers such as boxes and packs. The film can be used in the field of packaging films such as bags, printing paper, and the like, and highly foamed materials, foamed beads, and the like are useful as cushioning materials.

In the molded article of the present invention, it is ideal that the core layer is substantially completely surrounded by the moisture-proof coating layer. However, the core layer is formed by a method for producing the molded article or a subsequent processing of the molded article. It may be partially exposed, and in this case, if necessary, the exposed portion is coated with a coating solution capable of forming a moisture-proof coating, or subjected to a rapid heating treatment or a flame treatment, for example. Water resistance can be improved. The waste after use of the molded article of the present invention is crushed and buried in the soil as a fertilizer, and the starch contained therein is decomposed by microorganisms or by an enzyme such as α-amylase and taken in as a nutrient source of the plant, and the starch is released. The remaining filler and some resin whose composition has collapsed are powdered and scattered in the soil without any problem and are in the ecological circulation system. As described above, one of the great advantages is that the molded article of the present invention does not require a special disposal treatment unlike a synthetic resin.

An effective waste disposal method after use of the molded article of the present invention is a treatment in a water tank, which is pulverized and thrown into a water tank, and vortexed with water, blows air, and rubs between vibrating rolls. And elutes and removes water-soluble substances such as natural polymers by heating, etc., and separates after the filler has fallen off or the resin has become water-insoluble and powdered. This process is repeated and the water tank is installed at many stages, and the shape of the molded product collapses. The filler dropped from the molded product can be separated and recovered, and the natural polymer eluted in water can be used as it is as an aqueous solution or separated and used for feed or fertilizer or reused.

The starch molded product of the present invention can be used similarly to synthetic resins and paper pulp products, and the main raw material is starch.
Starch is an agricultural product of artificial cultivation resources, is inexpensive, and can be expected to increase production and lower price. Unlike pulp and paper resources, reproduction does not catch up with demand and does not lead to the destruction of forest resources, reduces the use of petroleum, a finite resource, and wastes pollute the global environment Don't worry about doing it. Furthermore, the moisture-proof starch molded product of the present invention can be mass-produced by the conventional synthetic resin film formation molding equipment technology.

Next, the present invention will be described more specifically with reference to examples.

[0062]

Example 1 Starch Constarch 60 kg Filler Talc MS Average particle size 9μ 40 Water Tap water 15 Modifier 3EDMA 1: Phthalic anhydride 1 1 Hydrophilic resin Water-soluble nylon 5 Additive Fatty acid alcohol amide 1 Foaming agent Bicarbonate Sodium 2 The above mixture was stirred with a mixer at 55 ° C. for 5 minutes to obtain wet coarse particles, and molded using the apparatus shown in FIG.

The extruder (2) heats and melts the mixture at 90 ° C. to 120 ° C., cools and regulates the temperature with a stellar mixer / T die (3) and a cooling device (4), and forms a gelatinized starch sheet having a thickness of 270 μm at 92 ° C. Produced in a drying oven (5) with a water content of 9 wt%
The starch composition sheet (1-a) has a thickness of about 240 μm.

The modifier (3EDM) is applied to the modifier applying device (7).
A 4: phthalic anhydride 2: organic peroxide 1: mixing ratio)
Sheet (1-wt.)
The composition was applied to both sides of a), the alcohol content was removed in a drying oven (8), and the mixture was flame-treated.

On the other hand, polypropylene C was fed from the feeding device (9).
30 μm of the PP film is fed out, melt-extruded and coated with an adhesive polypropylene to a thickness of 2 to 3 μm by a coater (10), and the sheet (1-b) is laminated on the modifier-coated surface of the sheet (1-a) while the sheet (1-b) is an endless belt. (12) It is fed between the [belt supporting heating rolls (13)] and fastened between the belts.

Subsequently, the heating device (15) and the heating roll (1)
6) are placed and heated to 200 ° C. to 240 ° C., and the moisture-proof CPP film is tightly joined by heat denaturation of the adhesive resin and the starch-combined sheet bonding surface, between the cooling roll (17) and the cooling device (19). 3 times foaming 900 with gap roll (18)
μm and cooled between the endless belt (12) and the belt-supporting cooling roll (20).
c) was obtained.

This rigid plate-like foamed sheet can be used as paperboard, cardboard, liner carton paper.

Example 2 Starch potato starch 9: CMC 170 kg Filler Charcoal 30 Water Tap water 20 The above mixture was stirred and mixed with a mixer at 50 ° C. for 8 minutes to form wet coarse particles and molded with the apparatus shown in FIG. did.

The extruder (2) heats and melts at 90 ° to 110 ° C., cools and cools with a cooling device (4) directly connected to a T-die (3), and forms a gelatinized starch sheet having a thickness of 34 μm at 90 ° C. The starch composition sheet (1-a) having a water content of 10 wt% is made 30 μm thick in a drying furnace (5).

The modifier (3EDM) is applied to the modifier applying device (7).
A3: phthalic anhydride 2: acrylic acid monomer 4: organic peroxide 1) was applied to both sides of the sheet (1-a) as an 8 wt% ethyl alcohol solution to remove the alcohol content.

Subsequently, EVA 2 μm was applied using an adhesive layer coater (8).
m is coated and laminated on both surfaces of the sheet (1-a), LDPE 5 μm is coated and laminated by the moisture-proof layer coater (9), and is pressure-tightened by the nip roll (6) and sent to the heating furnace (10).

The sheet is heated to 190 ° C. to 220 ° C. in a heating furnace (10) while being fed by a support belt (11) to improve the physical properties by a melt decomposition reaction.
b) is discharged and cooled by a cooling roll (12) and a cooling device (13) to obtain a moisture-proof starch molded product (1-c) having a thickness of 45.
μm was obtained.

This film had a wrapping paper feel and was suitable for use in that application.

Example 3 Using a three-layer stacking extruder shown in FIG. 3, a feeder shown in FIG. 4 was used to form three types and five layers as follows.

Starch Constarch 70 kg Filler Charcoal 7.5: Wood flour 2.5 30 Water Distilled water 25 Modifier EDMA 1.5 Hydrophilic resin PVA 5 Additive PEG 1: LDE 1 3 The mixture is stirred and mixed at 75 ° C. for 25 minutes, and the mixture is put into a 65 mm extruder (2) as a mixture for a core layer with a water content of 15 wt%.

EVA 90 wt% and denaturant 10 wt% (3
EDMA 3: acetic anhydride 2: styrene monomer 4: organic peroxide 1) and mix the mixture into a 30-mm extruder (3) for an adhesive layer (intermediate layer).

LDPE is introduced into a 40 mm extruder (4) for use as a moisture-proof skin layer.

Extruder (2) 180 ° -210 ° C. 300 μm 30 extruder (3) 180 ° -200 ° C. 5 μm × 2 40 Extruder (4) 190 ° -220 ° C. 20 μm × 2 laminated sheet Each extruder, feed block (5), T-die (6), and cooling device (7) were adjusted to obtain a sheet-shaped moisture-proof starch molded product having a thickness of 700 μm and an overall expansion ratio of about 2 times.

This foamed sheet can be molded and used in the same manner as general-purpose thermoplastic resin molding such as vacuum / pressure molding, and is suitable for trays, lunch boxes and the like.

Example 4 Using the laminating extrusion apparatus shown in FIG. 3, a molded product is obtained as follows using a laminating die shown in FIG.

Starch Corn starch 8: Acrylamide copolymerized starch 2 50 kg Filler Charcoal 9: Pulp powder 1 50 Water Tap water 25 Hydrophilic resin PVA 5 Foaming agent ADCA 1.5 Mix the above mixture at 75 ° C for 30 minutes with a mixer. And water content 1
The mixture is introduced as a core layer into a 65 mm extruder (2) as a 1 wt% mixture.

EVA 88 wt% and denaturant 12 wt% (E
DMA 3: styrene monomer 4: organic peroxide 1) and charge the mixture as an adhesive layer (intermediate layer) into a 30 mm extruder (3).

LDPE is introduced into a 40 mm extruder (4) as a moisture-proof skin layer.

Extruder 65 (2) 180 ° to 210 ° C.
1 mm φ Round bar shape 30 mm Extruder (3) 180 ° -200 ° C Thickness 25
μm on the outer circumference of 1 mm φ round bar 40 mm extruder (4) 190 ° -220 ° C. Thickness 10
0 μm on the outer periphery of (1.050 μmφ) by extrusion lamination sequentially with a lamination die (5) to 1250 μm
Shape φ round bar.

A round bar produced on the side of the discharge port (6) of the laminating die (5) was cut with a cutting device (7) covering the adhesive layer and the moisture-proof layer and cutting it at intervals of 4 mm.

The cut product having a diameter of 1.25 mm and a length of 4 mm was immediately expanded to obtain a foamed moisture-proof starch molded product (1) having a diameter of about 6 to 8 mm and a length of about 20 times the length of about 20 mm.

This highly foamed molded product is used as a cushioning material.

Example 5 The operation is carried out by using the laminating apparatus shown in FIG. 3 and the laminating die and the water tank shown in FIG.

The same operation as in Example 4 was carried out, and the laminated die (5)
The discharge port (6) is in contact with the water in the water tank and rotates in contact with the discharge port (6), and the discharge round bar is covered with the moisture-proof layer and cut in water (cut underwater). A 2.5-mm pellet-shaped moisture-proof starch molded product was obtained.

The pellets can be used as expandable beads which expand by heating.

Example 6 This was carried out using a tandem array extruder shown in FIG.

Starch potato starch 9: CMC 1 60 kg Filler talc MS 4: pulp powder 1 40 water Distilled water 20 Modifier EDMA 2 The above mixture was stirred and mixed with a mixer at 60 ° C. for 30 minutes to obtain a crude water having a moisture content of 12 wt%. Granular.

The first stage 65 extruder (2) was charged and
The mixture is heated and kneaded to 0 ° to 210 ° C., subjected to a melt-decomposition process, and then sent to a second-stage 90-abrasion extruder (3), where the temperature is 200 ° C. → 90 ° C.
And extruded at 93 ° C 400 μm thick from T-die (4)
The sheet (1) is produced. Corona discharge is applied to both sides of the sheet, adhesive polypropylene 30 wt%, modifier 70 w
t% (mixing ratio of EDMA 2: acetic anhydride 1: styrene monomer 6: organic peroxide 1) to 20 wt% of benzene
The liquid was applied to the surface and dried, and then subjected to a flame spray treatment to obtain a moisture-proof starch molded product having a moisture permeability of 30 g / m ² · 24 hr.

This sheet was used for a cardboard box.

Example 7 The operation was carried out using an in-line screw injection molding machine shown in FIG.

Natural polymer Corn starch 60 kg Fine material Talc 8: Mica 3 40 Water Purified water 25 Modifier 3 EDMA 1: Acetic anhydride 1 3 Other compounding agents Solvent LDE 3 All the above compounds are stirred and mixed by a mixer at 75 ° C. for 25 minutes. The mixture was formed into coarse particles having a water content of 9 wt%, and the mixture was injected into a 40 ° C mold (3) at 180 ° to 240 ° C using an inline screw injection molding machine (2) to form a starch composition (1).

The modified product described in Example 1 was sprayed on the surface of the molded product to remove the alcohol, and a silicone resin was sprayed on the surface and heat-treated in a furnace at 120 ° to 160 ° C.
A moisture-proof starch molded product was obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart for manufacturing a sheet-like molded product using an endless belt.

FIG. 2 is a flowchart for producing a sheet-like molded product in an open state.

FIG. 3 is a plan view showing an arrangement of a three-layer extruder.

FIG. 4 is an explanatory sectional view of a feed block and a die for a three-type five-layer sheet-like molded product.

FIG. 5 is an explanatory sectional view showing a laminated state in which linear round bars are laminated and extruded.

FIG. 6 is a layout side view of the tandem array extruder.

FIG. 7 is an explanatory sectional view of an in-line screw injection molding machine.

Claims (2)

(57) [Claims] The present invention provides a gelatinized composition comprising a starch, an incompatible solid filler and water as a basic compound.
What is claimed is: 1. A moisture-proof starch molded product comprising 20% by weight of at least a surface-modified core layer and a moisture-proof coating layer bonded to the surface of the core layer. 2. The core layer according to claim 1, wherein the surface of the core layer has a moisture permeability of 5.
0g / m ² / 24hr moisture starch molding having no moisture barrier is a resin-modified below.