JP2000129600A - Production of molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a molded product having excellent thickness and surface strength, applicable even to a material such as pulp, etc., friendly to an environment. SOLUTION: A slurry comprising a composition having >=550 mL Canada Standard Freeness(CSF) is used. Water as a medium for the slurry is removed from a great number of small holes of a molding mold having the small holes so that a small hole impenetrable fine component in the slurry is piled in the molding mold to give a wet molded product having >=10 mm thickness of the piled layer. The wet molded product is dried inside or outside the mold. Immediately after the drying, outside the mold, before the surface temperature of the dried molded product is dropped to a normal temperature, the dried molded product is subjected to a surface strength-up treatment by an apparatus in close proximity to a molding apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing a molded product having a good thickness and a high surface strength, which is applicable to materials such as pulp which is environmentally friendly.

[0002]

2. Description of the Related Art Styrofoam conventionally used as a cushioning material has excellent characteristics such as cushioning and heat insulation, and can be easily processed into an arbitrary shape, and is inexpensive and lightweight. And the appearance is good. However, in recent years, as interest in environmental issues has increased, like other so-called plastic products, there has been an increasing demand for treating the processability after use. In other words, it has been pointed out that in the case of incineration after use, damage to the furnace and generation of toxic gas due to generation of high temperature. Further, when the landfill treatment is performed, it is considered to be one of the causes of shortage of the treatment plant because it is not decomposable and is bulky.

Recently, pulp molds have been attracting attention as a cushioning material to solve the problems in the processing of polystyrene foam, and are increasingly used as substitutes for polystyrene. The pulp mold is manufactured using recycled pulp as a raw material, and can be given a buffering power and strength by devising its shape, and can be easily incinerated or landfilled.

However, in a conventional pulp molding method in which pulp in a slurry is deposited on a mold having a large number of small holes while sucking and dewatering, and then dried to obtain a molded product, pulp in the mold is not used. As the accumulation of pulp fiber progresses, the adhesion between pulp fibers progresses, and the drainage becomes worse.Therefore, it takes a long time for the suction and dewatering steps to obtain a molded product with a thick sedimentary layer. Has a thickness of 10
mm could not be obtained. For that reason,
Insufficient cushioning properties, and to make up for it, it is necessary to devise structural measures such as adopting a rib structure. To take a long time. In addition, there is a problem that the mold is extremely expensive because it takes time to design and manufacture, and the manufacturing cost of small lot products becomes extremely high. In addition, the rib-structured shock absorber exerts a sufficient effect on the first drop impact, but is extremely poor in shock resistance on the second and subsequent drop impacts. He had problems.

[0005]

As a means for solving this problem, the present inventors have disclosed Japanese Patent Application Nos. 9-10343 and 1
0-32920 and 10-33551, the use of a Canadian Standard Freeness (CSF) of 550 ml or more, which has excellent drainage, as a slurry composition, suppresses the adhesion between fine pore-impermeable fine components and reduces the water content. It has been found that the removal is improved, and a molded product having a sufficient thickness can be efficiently obtained even by the suction / dehydration molding method of the slurry, and it has been found that the following merits arise. A molded article applicable to heavy objects is obtained. A molded article exhibiting excellent shock-absorbing properties against the second or subsequent drop impact is obtained. In addition, since there is no need to devise structural measures such as the rib structure, complicated molds such as the conventional pulp molding method are not required, and the time required for mold design and manufacturing can be greatly reduced. The mold can be manufactured at low cost. Since the mold can be manufactured at low cost, productivity can be increased by increasing the number of attached molds, and the production cost can be suppressed to a relatively low production cost even for a small lot.

However, when such a raw material having good drainage is used, the surface strength is extremely poor as compared with that obtained by the conventional pulp molding method, and the falling off substances (for example, paper powder when pulp is the raw material) are generated. For example, when it is used as a packaging material, there are problems such as contamination of wrapped goods, and contamination of air and workers in a manufacturing site or a handling work place. An object of the present invention is to eliminate the problem of insufficient surface strength of a molded product, which is a problem when using a slurry composition having a Canadian standard freeness (CSF) of 550 ml or more and having excellent drainage, and having a good thickness. Another object of the present invention is to provide a molding method capable of producing a molded product having surface strength with high production efficiency.

[0007]

Means for Solving the Problems In view of the present situation, the present inventors have intensively studied a molding method capable of efficiently producing a molded article having a good thickness and surface strength.
After forming a molded article using a slurry composition having a specific Canadian Standard Freeness (CSF) as a raw material, the surface temperature of the molded article is kept at room temperature or higher, and the next treatment for increasing the surface strength is performed. It has been found that this can be achieved by the application, and the present invention has been completed.

That is, the present invention uses a slurry comprising a composition having a Canadian Standard Freeness (CSF) of 550 ml or more to remove water, which is a medium of the slurry, from small holes of a mold having a large number of small holes. By depositing the fine pore-impermeable fine components in the slurry on the molding die to form a wet molded product, the wet molded product is dried inside or outside the mold, and immediately thereafter, the dry molding is performed outside the mold. This is a method for producing a molded article, characterized in that a surface strength increasing treatment is performed by an adjacent device before the surface temperature of the molded article falls to room temperature.

In the present invention, the molded product preferably has a portion where the thickness of the deposited layer is 10 mm or more. In the present invention, it is preferable that the surface strength increasing treatment is application of an adhesive to the surface of a molded product. In the present invention, it is preferable that the surface strength increasing treatment is bonding of the film to the surface of the molded product. In the present invention, the main component of the slurry composition is preferably pulp. Preferably, the pulp is a curled fiber. Further, it is preferable that the pulp is used paper fiber that has been subjected to at least one of water repellency, water resistance, and curing. In the present invention, it is preferable that the main component of the slurry composition is a cellulosic coarse powder. Further, it is preferable that the cellulosic coarse powder is obtained by mechanically pulverizing wood.
In the present invention, it is preferable that the density of the dried green body subjected to the surface strength increasing treatment is 0.02 to 0.30 g / cm ³ .

[0010] The primary cause of the success of the present invention is the adhesion between small pore-impermeable microcomponents that occurs when attempting to obtain thick moldings using a slurry composition having a Canadian Standard Freeness (CSF) of 550 ml or more. The problem is that the problem of insufficient surface strength caused by poor properties can be solved by a surface treatment in a later step. A second cause of the success of the present invention is that it has been found that by performing the surface treatment before the surface temperature of the dry molded product is lowered to room temperature, the heat improves the treatment efficiency.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses a slurry composition having a Canadian standard freeness (hereinafter referred to as "freeness") of 550 ml or more, forms a wet molded product, and then dries it. The surface treatment is carried out before the surface temperature decreases to room temperature to increase the surface strength.

As the slurry raw material of the present invention, a single material having a freeness of 550 ml or more must be used, but a slurry having a freeness of less than 550 ml must be used in a combined system with other materials. it can. As the main raw material, for example, most of the impervious to the small holes of the mold, natural organic polymer fiber, synthetic organic polymer fiber, semi-synthetic organic polymer fiber, natural organic polymer coarse powder and fine particles, Synthetic organic polymer coarse powder / fine particles, semi-synthetic organic polymer coarse powder / fine particles, inorganic fibers, inorganic coarse powder / fine particles, and fibers or coarse powder / fine particles of an organic-inorganic composite material. Among them, those preferred as main raw materials are:
Those having a freeness of 550 ml or more, particularly preferably those having a freeness of 600 ml or more, by which the molded article is particularly excellent in low density and productivity. As a matter of course, the raw materials recovered for recycling can also be used. The size of the raw material is not particularly limited, but is usually in the range of 0.1 to 50 mm in consideration of the dispersibility when forming a slurry and the raw material yield during molding. These raw materials may be used in combination of two or more. The following are more specific examples of the raw material.

Examples of the natural organic polymer fiber include unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of coniferous or hardwood, GP, RMP, TMP, CTMP, etc. Mechanical pulp, or cotton pulp, linter pulp, waste paper pulp, liquid ammonia-treated pulp, mercerized pulp, cellulosic fiber such as curled fiber, hemp fiber, bamboo fiber, and protein fiber such as wool, silk, and collagen fiber; Complex sugar chain fibers such as chitin / chitosan fiber and alginic acid fiber are exemplified. As synthetic organic polymer fibers, for example, polyethylene fibers, polypropylene fibers,
Examples include polyethylene-polypropylene sheath core fiber, polyacrylonitrile fiber, acrylic fiber, polyester fiber, aliphatic polyester fiber, polyamide fiber and the like.
Examples of the semi-synthetic organic polymer fibers include acetylcellulose fibers.

Examples of the natural organic polymer coarse powder and fine particles include coarsely crushed or unground rice husks of cellulosic materials such as wood chips, bacas, rice straw, rice hulls, beer lees, and soybean lees.
Cellulose coarse powders such as sawdust, beer lees, soy lees and the like can be mentioned. Examples of the synthetic organic polymer coarse powder and fine particles include beads of synthetic resin such as polyethylene and polystyrene, coarsely crushed foamed resin such as expanded polystyrene, foamed microcapsules, and crushed old tires.
The semi-synthetic organic polymer coarse powder / fine particles include, for example, coarsely pulverized acetyl cellulose.

As the inorganic fiber, for example, glass fiber,
Examples thereof include carbon fiber, alumina fiber, silicon carbide fiber, silica / alumina silicate fiber, rock wool fiber, and stainless steel fiber. Examples of the inorganic coarse powder / fine particles include shirasu balloons, glass beads, granular activated carbon, and the like.

Among these, in terms of shape, needle-like or fibrous or those obtained by subjecting them to deformation treatment such as curling are preferable because of their excellent low density and cushioning properties. In terms of materials, natural organic polymer fibers, coarse powder, fine particles,
A coarsely crushed aliphatic polyester fiber, acetylcellulose fiber, or acetylcellulose has biodegradability and is environmentally friendly and preferable. Above all, cellulosic fiber or cellulosic coarse powder is preferable because of its excellent low density and easy material procurement.

Among the cellulosic fibers, those having a freeness of 550 ml or more in terms of low density and productivity of the molded product,
Among them, those having 600 ml or more, particularly those having 650 ml or more are preferable. Among the cellulosic fibers having a freeness of 550 ml or more, those which have been subjected to at least one of water repellency, water resistance, and curing can provide a molded article particularly excellent in terms of low density and buffer properties. It is preferred. Among them, a curled fiber having a curled shape is particularly preferable since a molded article excellent in low density and cushioning property can be obtained. In particular, among curled fibers, curled fibers having a wet curl factor in the range of 0.4 to 1.0 have a property that the curl shape is well maintained even when dispersed in water for a long time. It is particularly preferable because it is suitable for stably producing a molded article having excellent low density and cushioning properties for a long time.

Incidentally, the wet curl factor is an index indicating the degree of deformation of the fiber in a wet state, and the actual length (LA) of the fiber after immersing the curled fiber in pure water at room temperature for 24 hours. And the maximum projected length of the fiber (the length of the longest side of the rectangle surrounding the fiber, LB) is measured using a microscope,
This is a value calculated by [(LA / LB) -1], which is a numerical value indicating how much the fiber is curved from the original length of the linear fiber.

The curled fiber is a pulp fiber having an apparent length smaller than that of the original fiber, in which deformation such as curling or twisting is fixed by chemical bonding by a crosslinking reaction. Usually, it is obtained by adding a cross-linking agent to the cellulosic fiber, performing mechanical stirring to deform the fiber, and then performing fluffing and heat treatment to fix the deformation. Known ones include, for example, C2-
C8 dialdehyde and C2 to C8 having an acid function
Crosslinked fiber having an average water retention of 28% to 50% obtained by crosslinking the inside of a cellulosic fiber using the monoaldehyde of the formula (Japanese Patent Publication No. 5-71702), and a cellulosic fiber using a C2 to C9 polycarboxylic acid. Water retention 2 with internal cross-linking
5% to 60% crosslinked fiber (Japanese Patent Application Laid-Open Nos. 3-206174, 3-206175, 3-206)
176) and commercially available products, for example, trade name: HBA-F, manufactured by Warehauser, USA
F, NHB405, NHB416 and the like.

Among the cellulosic coarse powders, those having a freeness of 550 ml or more in terms of low density and productivity of molded products,
Among them, those having 600 ml or more, particularly those having 650 ml or more are preferable. Among the cellulose-based coarse powders having a freeness of 550 ml or more, those obtained by increasing the freeness to 550 ml or more by removing a fine region by performing an 80 mesh pass treatment are preferable. Further, among the cellulosic coarse powders, needle-like or fibrous ones are preferable because they have excellent low density and buffer properties, and easily exhibit interlayer strength. Above all, needle-like ones are particularly excellent in buffering property and are preferable. Among needle-shaped and fibrous shapes, coarse powders obtained by coarsely pulverizing wood chips, such as those used for particle board raw materials, are excellent in low density and easy to procure raw materials. Particularly preferred. Examples of the pulverization method include a well-known method in the particle board industry, such as an asplund method.
Those crushed at a high temperature of 130 ° C. or more, particularly at a high temperature of 130 ° C. or more, tend to have higher rigidity than those crushed at a lower temperature, and therefore are likely to be excellent in low density and cushioning property. As the pulverizing treatment, a weak treatment that does not normally become a raw material for paper, such as a single-stage treatment in a refiner, is preferable because it tends to have high rigidity. In addition, as a means for increasing the rigidity, a method of performing a crosslinking reaction treatment, a hydrophobic treatment, and a surface resin treatment before and after the pulverization treatment of the wood chips is also effective. In the case of the above-mentioned pulverized product or the processed product further subjected to curling treatment with a kneader or the like, the improvement of the buffering characteristics becomes more remarkable. Also, among coarse powders, a fine area is removed by passing 30 to 200 meshes to increase the freeness to 550.
When the content is increased to not less than ml, the wastewater treatment during the production of the molded body is easy, and the raw material yield during the production of the molded body is good. The main raw material is usually blended in a range of 60 to 100% by weight based on the absolute dry weight of the slurry composition.

When the desired interlayer strength is not obtained by using only the above-mentioned raw materials, it is effective to add natural pulp-based fine fibers and an adhesive to the slurry. Among them, natural pulp-based fine fibers are particularly preferable because they have such advantages as an effect of increasing the interlayer strength, and easy drainage treatment at the time of manufacturing a molded article.

Natural pulp-based fine fibers include conifers,
Unbleached or bleached chemical pulp obtained by hardwood kraft pulping, sulfite pulping, alkali pulping, etc.
Alternatively, mechanical pulp such as GP, RMP, TMP, and CTMP, or natural pulp fiber such as cotton pulp, linter pulp, and waste paper pulp, is further wet-processed with a medium stirring mill, a vibration mill, a high-pressure homogenizer, a colloid mill, a beater, and the like. Number average fiber length obtained by mechanical processing 0.01 to 0.80 m
m. Among them, fine fibers having a bond reinforcing factor of 0.15 or more are particularly preferable since the effect of increasing the interlayer strength is particularly remarkable.

The binding enhancement factor (BF) referred to in the present invention.
Is calculated by (E2−E1) / E1. However, E1
Is a mixture of bleached hardwood kraft pulp 50% by weight and softwood bleached kraft pulp 50% by weight to form an aqueous slurry,
After beaten to 500 ml of Canadian Standard Freeness (CSF), dewatered and air-dried with a hand making machine according to JIS-P-8209 to produce a sheet having a basis weight of 60 g / m ² ,
The figure shows the ultrasonic elastic modulus measured after heat treatment at 30 ° C. for 2 minutes and humidity control at 20 ° C. and 65% RH. E2 indicates the ultrasonic elastic modulus when an aqueous slurry was prepared by replacing 50% of the pulp fibers with fine fibers, and a sheet was prepared and measured in the same manner as in the measurement of E1. Two or more of the above-mentioned natural pulp-based fine fibers may be used in combination. The fine fibers are usually 0 to 35% by weight based on the absolute dry weight of the slurry composition.
Is added within the range.

Examples of the adhesive include resins such as urea formaldehyde resin, melamine formaldehyde resin, polyamide urea formaldehyde resin, ketone resin, polyamide epichlorohydrin resin, polyamide polyamine epichlorohydrin resin, glycerol polyglycidyl ether resin, polyethylene imine resin, starch, and the like. Water-soluble binders such as processed starch, vegetable gum, gelatin, PVA, and CMC; emulsions such as vinyl acetate resin, acrylate resin, ethylene-vinyl acetate copolymer, and styrene-butadiene copolymer; The adhesive is usually added in the range of 0 to 25% by weight based on the absolute dry weight of the slurry composition.

In addition to the above-mentioned raw materials, a water-resistant agent, a water-repellent agent, a foamable microcapsule, a sizing agent, a dye, a pigment, Yield improvers, fillers, pH regulators, slime control agents, thickeners, preservatives, fungicides, antibacterials, flame retardants, preservatives, rodenticides, insect repellents, moisturizers, fresheners, deoxidizers , A microcapsule, a foaming agent, a surfactant, an electromagnetic shielding material, an antistatic agent, a rust preventive, an aromatic, a deodorant and the like can be selected and blended. These may be used in combination of two or more.

Examples of the water-proofing agent include formaldehyde having an aldehyde group, glyoxal, dialdehyde starch, and ammonium zirconium carbonate which is a polyvalent metal compound. Examples of water repellents include various waxes (natural wax, petroleum wax, chlorinated paraffin, wax emulsion, etc.), higher fatty acid derivatives,
Examples include synthetic resins, chromium complex salts, zirconium salts, and silicone resins.

The slurry used in the present invention is prepared by blending the above-mentioned raw materials so that the freeness becomes 550 ml or more, and is usually prepared batchwise or continuously by using a device having a stirrer. Water is usually used as a medium used for slurry formation. Alternatively, a mixture of water and an alcohol (methanol or ethanol) can be used. Heating the medium has the effect of increasing the drying rate. The concentration of the slurry is usually adjusted so that the dry solid content is in the range of 0.05 to 10% by weight, but preferably in the range of 0.05 to 3% by weight in terms of the dispersed state.

As a molding die, an ordinary pulp molding die can be used. However, when a block-like molded product is required, a deep-bottomed container having a large number of small holes (for example, a cylinder or a cylinder) is required. A cylindrical container such as a square tube) or a split container is usually used. (Hereinafter, in the present invention, the mold is referred to as a mold container)

The small holes of the molded container may have any shape such as a circle, an ellipse, a square, and a rectangle. The size of the pores may be such that the dispersion components other than water, which is the medium of the slurry, hardly leak, and usually have a diameter of 30 μm.
Circular ones in the range of μm to 3 mm are used, but are not particularly limited in the present invention. Like a mold used in a pulp mold, a mold in which a fine mesh is attached to a molding container wall having a relatively large hole can also be used. Further, the size of the small hole can be changed in the portion of the molding container.

The small holes need not necessarily be present on the entire surface of the wall of the molded container. For example, in the case of a cylindrical container, they may be present only on the bottom. In consideration of the dehydration efficiency and the like, it is preferable that small holes are present in a portion of 20% or more of the wall of the molding container, more preferably 35% or more. The number of parts to in pores small pores there is preferably made present one or more per cm ^2, and more preferably four or more per cm ^2.

In the case of a cylindrical container, the slurry is poured into a molding container having an opening opening upward by a pump from the opening, and the slurry is opened downward as in a normal pulp mold. The slurry is immersed in the tank and sucked into the forming container from the downward opening by sucking through the small hole. It is possible to take a method such as sucking it inside. In the case of a split mold container, a method such as press-fitting into a molded container using a slurry injection tube can be employed. As a method for removing the medium of the slurry from the small holes, there are a suction dehydration method, a gas pressure dehydration method, a mechanical pressure dehydration method, an electroosmotic dehydration method and the like, and these can be combined.

The wet filling formed in the molding container by dehydration is thereafter taken out of the container or taken out of the container and dried. In the case of drying in a container, a molded product having high dimensional accuracy can be obtained, but the productivity is poor. on the other hand,
In the case of drying outside the container, the dimensional accuracy is slightly inferior, but the productivity is excellent. As an intermediate proposal, a method may be adopted in which after drying in a container is performed halfway, the container is taken out and dried outside the container.

As a drying method, known methods such as hot air drying, infrared drying, microwave drying and the like can be used. Heating steam is effective for drying halfway. To increase the drying speed, heat air is injected into the wet molded product, or suction is applied from the opposite side of the molded product while heating air is being introduced, so that the air flow in the voids between the small pore non-passing fine components is increased. It is effective to improve it. Further, it is also effective to increase the surface area by intentionally forming irregularities on the surface of the molded article, or to improve the flow of air by forming a penetrating or non-penetrating hole in the molded article. When air is injected into the hole, a method may be employed in which a cylindrical projection having a small hole on the wall is inserted into the hole, and hot air is blown into the molded body through the small hole. In addition, a method in which the forming container is heated before pouring the slurry has an effect of increasing the drying speed.

As a method for forming irregularities or making holes in a molded product, a wet molded product inside or outside a molding container is post-processed by using a pressing press machine, a cutting machine, a water jet, an air jet, or the like. And a method in which the shape is imparted to a molded article simultaneously with molding using a molded container having irregularities or projections. The projections preferably have a tapered structure so that the molded product can be easily taken out of the container.

A thick molded article prepared by the above-mentioned method using a slurry composition having a Canadian Standard Freeness (CSF) of 550 ml or more is superior in terms of buffering properties and the like as compared with a normal pulp molded article. However, it is inferior in surface strength and needs improvement. The present invention is characterized in that the surface strength increasing treatment is performed on the molded product taken out of the mold before the surface temperature of the molded product immediately after drying is lowered to room temperature, compared with the case where the surface temperature is increased after the room temperature is reached. There are merits such as a large effect of improving the surface strength or good production efficiency. In particular, when heating is required in the surface treatment step, the effect is remarkable. The surface temperature is preferably 35 ° C. or higher, particularly preferably 50 ° C. or higher. The treatment is preferably performed in a device close to the molding device.

Preferred examples of the surface strength increasing treatment used in the present invention include application of an adhesive to the surface of a molded product and bonding of a film to the surface of the molded product. In this case, the process is simple and the effect of increasing the strength is great. In addition, in the case of (1), the effect of improving the buffering property can be expected in addition to the effect of increasing the surface strength.

Examples of the adhesive used for application to the surface of the molded product include starch, processed starch, CMC, hydroxyethyl cellulose, vegetable gum, gelatin, casein, PV
A, urea formaldehyde resin, melamine formaldehyde resin, polyamide urea formaldehyde resin, ketone resin, polyamide epichlorohydrin resin, polyamide polyamine epichlorohydrin resin, glycerol polyglycidyl ether resin, polyethylene imine resin,
SBR resin, acrylic resin, vinyl acetate resin, vinyl chloride resin, rosin-based resin, terpene-based resin, natural rubber, synthetic rubber, UV or EB-cured resin, and the like can be used alone or in combination. Can be. These are usually dissolved in water or a solvent, or as an emulsion, or in the case of a liquid, applied as they are. Among them, the use of an aqueous system is preferred in terms of the working environment. The coating is usually performed by spraying, brushing, impregnation, or the like. The coating amount is usually 0.1 to
50 g / m ² (surface area of the molded body). After application, drying and curing are performed using hot air, infrared rays, microwaves, ultraviolet rays, electron beams, or the like, as necessary. The dried state of the molded article to which the adhesive is applied is not necessarily perfect, but the moisture content is preferably 20% by weight or less from the viewpoint of the dimensional accuracy of the molded article.

The above-mentioned adhesive coating liquid may optionally contain a water repellent, a dye, a pigment, an antiseptic, a fungicide, an antibacterial agent, a flame retardant, a rodenticide, etc., as necessary, for improving the performance and imparting functions. , An insect repellent, a freshness-retaining agent, a deoxidizer, an electromagnetic shielding material, an antistatic agent, a rust inhibitor, a fragrance, a deodorant, and the like.

Examples of the film used for bonding to the surface of the molded product include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, nylon, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl acetate alcohol. Polymer (EVAL), polycarbonate, polyester (PE
T), aliphatic polyester, acetate, cellophane and the like. Among them, a film made of a biodegradable resin or a water-soluble resin is particularly preferable because it can be easily disposed of. Specifically, Bionole (Showa Kogaku), Lacia (Mitsui Chemicals), Lunar ZT (Nippon Shokubai), cellophane,
Polyvinyl alcohol and the like. Further, a film having a pigment or a small hole can be used as the film. In the present invention, a film having a thickness of usually 3 to 100 μm is used. As a method of laminating, an aqueous or solvent-based adhesive, a hot-melt type or a non-solvent type adhesive or a pressure-sensitive adhesive is applied to the surface of the film, and then dried in some cases. Laminating, bonding at room temperature or under heating, applying an aqueous, solvent, hot melt, or solventless adhesive or pressure-sensitive adhesive to the surface of the molded product, and then drying in some cases. A method of laminating a film on the surface of the molded product and bonding it at room temperature or under heating, a method of applying water to the surface of the film and then superimposing it on a surface of the molded product and bonding at room temperature or under heating, during drying Alternatively, it is possible to use a method such as a method of laminating a film on a molded product whose surface is wet by applying water after drying and bonding the film at room temperature or under heating. Examples of the method of wrapping the molded product include a method of wrapping the entire surface of the molded product with one film at a time, and a method of bonding and wrapping the film in units of the surface of the molded product.
Above all, a shrink film in which a single film covers the entire surface of the molded article at once is preferable because of its high production efficiency. When wrapping by the shrink method, if the molded body has a concave portion, it is preferable to perform suction from inside or pressurize from outside so that the film and the surface of the molded body are completely adhered. When suctioning from the inside or pressurizing from the outside, it is desirable that the inside of the film be kept at 1 atm after bonding. As an adhesive or adhesive used for bonding,
For example, a vinyl acetate resin, an acrylic resin, an SBR resin, an acrylic pressure-sensitive adhesive, or the like can be used.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. FIG.
6 to 6 are cross-sectional views showing an embodiment of the present invention. Here, a description will be given using a pulp slurry having good drainage as the slurry, but the raw material of the present invention is not limited to this. As shown in FIG. 1, the molding container 10 is a double-walled container having an open-top cylindrical shape, having a large number of small holes 11 for dehydration on the inner wall, and a step portion provided on the inner peripheral portion at the bottom of the inner wall. A suction chamber 13 is formed by an inner and outer double wall, and a suction port 14 is attached to the bottom of the outer wall. Although the shape of the lower mold 12 is schematically illustrated as a simple one with a stepped portion, the shape of the unevenness may be more complicated according to the shape of the product protected by the cushioning material.

FIG. 1 shows a state in which a pulp slurry 16 having good drainage is injected from an upper guide 15 while a lower suction port 1 is provided.
4 shows a state in which pulp is deposited so as to swell on the open surface of the container by suction dewatering from the container 4, and filling of the container 10 with pulp is completed. Reference numeral 17 denotes water droplets oozing out by suction, and reference numeral 18 denotes a wet pulp filling.

FIG. 2 shows a state in which an unnecessary portion raised and deposited on the open surface of the molding container of FIG. Cutting is performed while moving the water jet nozzle.

FIG. 3 shows a press machine 20 having a flat bottom surface and a large number of small holes 21 on the bottom surface. Indicates a dry state. At this time, if suction is performed from the suction port 14, drying proceeds more efficiently.

FIG. 4 shows a molded product 23 obtained by taking out from the molding container 10 after drying. By the way, if the bottom of the press upper die 20 of FIG. 3 is made to have a special shape, a molded product having a more complicated surface shape can be obtained.

FIG. 5 shows a state in which the water-based adhesive is sprayed on the surface of the molded product 23 immediately after drying and the surface temperature of which is still high.

FIG. 6 shows a final molded product 24 obtained by drying after applying the adhesive. This drying speed is much faster than when the treatment is performed after the surface temperature has decreased to room temperature. This final molded product 24 has significantly better surface strength than the molded product 23 that has not been subjected to surface treatment.
In addition, the surface strength improving effect tends to be greater than that of the surface treated after the surface temperature is lowered to room temperature.

The molded product obtained by the method of the present invention is
In addition to cushioning materials for packaging and the like, it can be widely applied to fields in which foamed resin molded articles are currently used, such as building materials and tatami core materials. Hereinafter, the present invention will be described in detail with reference to examples, but of course, the present invention is not limited thereto. In Examples and Comparative Examples, “parts” and “%” indicate “parts by weight” and “% by weight” unless otherwise specified.

Example 1 Unnecessary newsprint (200 g, absolutely dry weight) was cut by a press cutter and cut to 50 mm × 50 m.
m, and then imidazolidone-based crosslinking agent (trade name: Sumitex NF-500K, manufactured by Sumitomo Chemical Co., Ltd.)
Aqueous solution 2 containing 6 g and 3 g, respectively, in terms of active ingredients
00g. The used paper impregnated with the crosslinking agent is placed in a wet condition in a 1-liter double-arm kneader (model: S1-1, manufactured by Moriyama Seisakusho), and the double arms are rotated at room temperature at 60 rpm and 100 rpm, respectively, for 40 minutes. Kneading treatment was performed. Next, the used paper subjected to the kneading treatment was put into a Warburg blender in a wet state, and was fibrillated. Further, the fiber was taken out of the bag, put in a stainless steel bat,
The mixture was heated in a blow dryer at 30 ° C. for 30 minutes to complete the crosslinking reaction, thereby obtaining curled fibers. The wet curl factor of the used paper fiber which was curled at the same time as the crosslinking agent treatment was 0.53. When the freeness of this fiber was measured, it was 705 ml.

A water slurry of bleached kraft pulp having a solid content of 1% and a 80-% glass bead having an average particle diameter of 2 mmφ for a 1.5-liter dyno mill (model: KDL-PILOT type, Shinmaru. It was introduced and passed through an apparatus (manufactured by Enterprises) at 350 ml / min to obtain fine fibers having a number average fiber length of 0.28 mm and a bond reinforcing factor of -0.53. The water retention of the fine fibers was measured and found to be 285%. Water was added to a mixture of 95 parts of the recycled fiber and 5 parts of fine fibers obtained as described above to adjust the solid concentration to 1%, and the mixture was sufficiently stirred to obtain a pulp slurry.

Next, the pulp slurry was prepared using a small pulp mold manufacturing machine (model: SDM type, manufactured by Noritake Company) having a molding die capable of producing a disc-shaped molded body having a diameter of 100 mmφ and a thickness of 50 mm. After the pulp was deposited on the molding die by suction dehydration, the portion of the deposit protruding from the molding die was cut off using a water gun to obtain a disk-shaped wet molded product having a diameter of 100 mmφ and a thickness of 50 mm. Subsequently, the wet molded product was put into a blow dryer at 150 ° C. and completely dried.

Subsequently, a 10% aqueous solution of PVA (trade name: Gohsenol NH-18, manufactured by Nippon Synthetic Chemical Industry) was uniformly sprayed on the entire surface of the molded product having a surface temperature of 60 ° C. immediately after drying using a sprayer. It was applied so that the amount became 3 g / m ^2, and it was again put into a blow dryer at 150 ° C. and dried. still,
The time required for drying was 20 seconds. When the density of the obtained molded body was measured, it was 0.12 g / cm ³ .

In order to measure the amount of paper dust generated from the compact, the compact was placed on black paper of A0 size, and from a height of 300 mm from the upper end of the compact, a diameter of 80 mmφ and a height of 300 mm were measured. A 13 mm disc-shaped stainless steel product was dropped 50 times. Subsequently, the molded body is turned upside down for another 5 minutes.
Dropped 0 times. The paper powder generated by this was collected and its weight was measured to be 13 mg.

<Comparative Example 1> A surface-treated molded article was obtained in exactly the same manner as in Example 1 except that the surface temperature of the molded article during the spray treatment of PVA was lowered to room temperature. The time required for drying the surface treatment was 60 seconds. The amount of paper dust generated was measured by the same method as in Example 1, and was found to be 20 mg.

<Comparative Example 2> The amount of paper dust generated from the molded body obtained in the same manner as in Example 1 before the surface treatment was measured by the same method as in Example 1 and found to be 197 mg.

<Example 2> A starch (trade name: Ace A, manufactured by Oji Cornstarch) was added to a molded body having a surface temperature of 60 ° C, which had not been subjected to surface treatment, and was obtained in the same manner as in Example 1.
10% aqueous solution using a sprayer to make the solid content 3
g / m ^2, and then put again in a blow dryer at 150 ° C. and dried. The time required for drying was 12 seconds. The amount of paper dust generated from the molded product was measured by the same method as in Example 1 to be 28 mg.

Comparative Example 3 A surface-treated molded article was obtained in exactly the same manner as in Example 2 except that the surface temperature of the molded article during the spray treatment of starch was lowered to room temperature. The time required for drying the surface treatment was 50 seconds. The amount of paper dust generated was 42 mg.

Example 3 Vinyl acetate (trade name: Sakunol SN-04, manufactured by Denki Kagaku Kogyo Co., Ltd.) was applied to a molded body having a surface temperature of 60 ° C., which had not been subjected to surface treatment, and was obtained in the same manner as in Example 1. Was dissolved in a methanol / water mixture (50/50) to a concentration of 10%, and the whole surface was uniformly applied using a sprayer so that the solid content became 3 g / m ^2.
It was put into a blow dryer at 50 ° C. and dried. The time required for drying was 8 seconds. The amount of paper dust generated from this molded product was measured by the same method as in Example 1 and found to be 15 mg.

Comparative Example 4 A surface-treated molded article was obtained in exactly the same manner as in Example 3 except that the surface temperature of the molded article during the spray treatment with vinyl acetate was lowered to room temperature. The time required for drying the surface treatment was 30 seconds. The amount of paper dust generated was 28 mg.

<Example 4> An ethylene-vinyl chloride copolymer (trade name: Sumilite 1210, Sumitomo) was applied to a molded body having a surface temperature of 60 ° C, which had not been subjected to a surface treatment, and was obtained in the same manner as in Example 1. Aqueous thermosensitive adhesive aqueous solution obtained by adding a plasticizer (manufactured by Chemical Industry Co., Ltd.) and a solid plasticizer to water at a solid weight ratio of 2: 5 to adjust the concentration to 20%, and using a sprayer to uniformly uniform the solid content. 7 g / m ^2, and
It was put into a blow dryer at 50 ° C. and dried. The time required for drying was 27 seconds. Next, a vinylon film of 30 μm (trade name: Vinylon sheet # 3000, manufactured by Nippon Synthetic Chemical Co., Ltd.) was affixed to the entire surface of the molded body coated with the heat-sensitive adhesive. The amount of paper dust generated was 0 mg.

Comparative Example 5 A surface-treated molded article was obtained in exactly the same manner as in Example 4 except that the surface temperature of the molded article during the spray treatment of the heat-sensitive adhesive was lowered to room temperature. The time required for drying the heat-sensitive adhesive was 73 seconds. The amount of paper dust generated is 0
mg.

[0061]

As described above, the present invention uses a slurry composed of a composition having a Canda Standard Freeness (CSF) of 550 ml or more and removes the medium of the slurry from the small holes of a mold having a large number of small holes. This is a method of applying surface strength improvement treatment when the surface temperature immediately after drying the wet molded product obtained by removing the water is normal temperature or higher, so that the generation of paper powder excellent in low density and buffering property It is effective in providing a compact with little production efficiency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a molding container used for producing a molded article of the present invention, in which a solid content of a slurry is deposited on the molding container.

FIG. 2 shows a state where unnecessary portions accumulated on the open surface of the molding container of FIG. 1 are cut.

FIG. 3 is a cross-sectional view illustrating a state where a wet deposit in FIG. 2 is dried.

FIG. 4 is a cross-sectional view of the dried compact obtained in FIG. 3;

FIG. 5 is a view in which a chemical for increasing the surface strength is sprayed on the molded body of FIG. 4;

FIG. 6 is a sectional view of a final product obtained by the processing of FIG. 5;

[Explanation of symbols]

10: Mold (molding container), 11: Small hole, 12: Lower mold,
13: suction chamber, 14: suction port, 15: guide, 16: fiber slurry, 17: water droplet, 18: fiber deposit, 19: water jet, 20: upper die, 21: small hole,
22: Hot air port, 23: Dry molded product with high surface temperature, 2
4: Sprayer nozzle, 25: Final product

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L055 AA11 AF09 AF44 AF46 AG47 AG59 AG64 AG68 AG89 AH37 AJ02 BA10 BE08 BE14 BF09 EA05 EA08 FA13 FA16 GA04

Claims (9)

[Claims] The Canadian Standard Freeness (CSF) is 55
Using a slurry composed of 0 ml or more of the composition, water, which is a medium of the slurry, is removed from the small holes of the mold having a large number of small holes, and thereby the small components that do not pass through the small holes in the slurry are added to the mold. Is deposited into a wet molded product, and the wet molded product is dried in the mold or outside the mold. Immediately thereafter, outside the mold, before the surface temperature of the dry molded product falls to room temperature, the molding device is used. A method for producing a molded article, wherein a surface strength increasing treatment is performed by an adjacent device. 2. The method for producing a molded article according to claim 1, wherein the surface strength increasing treatment is an application of an adhesive to the surface of the molded article. 3. The method for producing a molded article according to claim 1, wherein the surface strength increasing treatment is bonding of a film to a molded article surface. 4. The method according to claim 1, wherein a main component of the slurry composition is pulp. 5. The method according to claim 4, wherein the pulp is a curled fiber. 6. The method for producing a molded article according to claim 4, wherein the pulp is waste paper fiber that has been subjected to at least one of water repellency, water resistance, and curing. 7. The method according to claim 1, wherein a main component of the slurry composition is a cellulosic coarse powder. 8. The method according to claim 7, wherein the cellulosic coarse powder is obtained by mechanically pulverizing wood. 9. The method for producing a molded article according to claim 4, wherein the density of the dried molded article subjected to the surface strength increasing treatment is 0.02 to 0.30 g / cm ^3.