JPH07119098A - Biodegradable board and molded article - Google Patents

Abstract

PURPOSE:To produce a light-weight paper board producible at a low cost, enabling fabrication such as draw forming by a hot-press and having biodegradability as the paper board and its formed article. CONSTITUTION:This paper board is produced by pressing or hot-pressing a mixture of 50-90wt.% of flake or fiber of a cellulosic material and 50-10wt.% of flake or fiber of a biodegradable aliphatic polyester resin, thereby melting and welding the polyester resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used as a biodegradable fiberboard or particleboard, or as a food cushioning material, food container, tray, seedling pot for agriculture and horticulture, etc., by various drawing processes by hot pressing. Pulp board useful as a next moldable board, or sound absorbing, building board for the purpose of heat insulation, perforated sound absorbing material, furniture material, building material such as wall, floor, ceiling, cushioning material, etc. Regarding a molded body.

[0002]

2. Description of the Related Art Conventionally, so-called fiberboards such as insulation boards, semi-hardboards, and hardboards do not use single fibers or fiber bundles obtained by crushing wood, pine resin soap, binders such as phenol-formaldehyde resin, at all. Alternatively, it is manufactured by a wet method in which a small amount is added and a dry method in which crushed fibers are dried and a considerable amount of a binder is added to form a board. After the board obtained by these manufacturing methods is once dried to determine the shape or after the binder is hardened to determine the shape, secondary molding by hot pressing or the like is impossible except for processing such as cutting. When a thermosetting resin such as phenol-formaldehyde resin is used as the binder,
The entire board loses its biodegradability and its disposal method does not result in degradation in soil. Especially one-way containers,
It is used in large quantities in cushioning materials for packaging etc. due to its convenience, but it is normally discarded after one use, and since it is not biodegradable, there is no way to treat it other than by incineration. Become.

Unlike the above-mentioned fiberboard, the particleboard is obtained by drying wood chips and then using a thermosetting resin such as urea resin or phenol resin as a binder to heat and pressurize the particles. It is a board and can be given various properties depending on the raw material, manufacturing method, etc.However, even though it is made of wood as a raw material, it has lost its biodegradability because it is a binder, so it must be incinerated for disposal. Is needed.

As described above, the fiber board or particle board has the advantages that it is lightweight, its thickness, shape, etc. can be arbitrarily selected and it can be manufactured at low cost, but it has no secondary moldability and biodegradability. A fundamental solution is required.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a light weight pulp board which can be manufactured at low cost, and is capable of secondary molding such as draw molding by hot pressing, and the board and its molded body. The purpose of the present invention is to develop a pulp board having a biodegradability as a whole, a method for producing the same, and a molded product thereof.

[0006]

According to the present invention, 50 to 90% by weight of cellulosic flakes or fibers and 50 parts of biodegradable aliphatic polyester resin flakes or fibers are used.
Pulp board characterized by pressurizing, or press-drying, a mixture of 10 to 10% by weight, and partially or wholly heating and pressing the above pulp board to melt the biodegradable aliphatic polyester resin The above-mentioned object is to develop a laminated pulp board in which a fusion-bonded pulp board, or one or both surfaces of these pulp boards is coated with a biodegradable aliphatic polyester resin, or a film of the resin is laminated. Was achieved.

Further, they have found that a pulp board can be easily produced by mixing paper-like flakes or fibers dispersed in water and flakes or fibers of a biodegradable aliphatic polyester resin, compressing and drying them. The present invention has been completed.

In the present invention, 50 to 90% by weight of cellulosic flakes or fibers and 50 to 10% by weight of biodegradable aliphatic polyester resin flakes or fibers are mixed, preformed into a container and dried. The above-mentioned object was achieved by developing a biodegradable molded product obtained by the above, or a biodegradable molded product obtained by further hot pressing this molded product.

The cellulosic flakes or fibers referred to in the present invention may be pulps such as wood pulp, linter pulp, rayon pulp, and thin small pieces of wood that can be easily corroded by microorganisms.

[0010] When the amount of lignin is large, the decomposition is blocked,
Pulp-based fibers are preferred.

The biodegradable aliphatic polyester resin mainly comprises a polyester synthesized from glycol and an aliphatic dibasic acid or its derivative, or has hydroxyl groups at both ends in order to sufficiently increase the molecular weight. Is obtained by synthesizing the polyester (prepolymer) having a relatively high molecular weight having ## STR4 ## and coupling the prepolymer with a coupling agent.

The polyester (prepolymer) for obtaining the aliphatic polyester to be coupled used in the present invention is obtained by reacting glycol with an aliphatic dibasic acid or its derivative, and the terminal group is substantially a hydroxyl group. Is a saturated aliphatic polyester having a number average molecular weight of 5,000 or more, preferably 10,000 or more, a relatively high molecular weight, and a melting point of 60 ° C. or more.

When the number average molecular weight is less than 5,000, for example, about 2,500, a polyester having good physical properties cannot be obtained even if a small amount of the coupling agent of 0.1 to 5 parts by weight is used. Number average molecular weight is 5,000
A polyester prepolymer of 0 or more can synthesize a high molecular weight polyester by using a small amount of a coupling agent without forming a gel during the reaction even under severe conditions such as a molten state.

Examples of glycols used include ethylene glycol, butanediol-1,4, hexanediol-1,6, decamethylene glycol, neopentyl glycol and 1,4-cyclohexanedimethanol. Ethylene oxide can also be utilized. These glycols may be used together.

As the aliphatic dibasic acid or its derivative which reacts with glycol to form an aliphatic polyester,
There are lower alcohol esters such as succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, succinic anhydride, adipic anhydride or dimethyl ester,
These are commercially available and can be used in the present invention. You may use together an aliphatic dibasic acid or its derivative (s). These glycols and the aliphatic dibasic acid or its derivative may be previously made into low molecular weight esters and polymerized by a deglycol reaction.

These glycols and aliphatic dibasic acids or their derivatives are mainly composed of aliphatic compounds, but small amounts of other components such as trifunctional or tetrafunctional polyhydric alcohols, oxycarboxylic acids and polycarboxylic acids or It is preferable to use a polyfunctional component such as the acid anhydride together.

The trifunctional polyhydric alcohol component is typically trimethylolpropane, glycerin or its anhydride, and the tetrafunctional polyhydric alcohol component is typically pentaerythritol.

As the trifunctional oxycarboxylic acid component, malic acid is practically advantageous, and as the tetrafunctional oxycarboxylic acid component, citric acid is practical because commercial products can be easily obtained at low cost. .

As the trifunctional polyvalent carboxylic acid (or acid anhydride thereof) component, for example, trimesic acid, propanetricarboxylic acid, etc. can be used, but trimellitic anhydride is advantageous in practical use.

Examples of the tetrafunctional polycarboxylic acid (or acid anhydride thereof) component include pyromellitic dianhydride, benzophenonetetracarboxylic acid anhydride and cyclopentanetetracarboxylic acid anhydride.

The proportion of the polyfunctional component used is such that the glycol component or the aliphatic (including cycloaliphatic) dibasic acid or its derivative component is a trifunctional component relative to 100 mol%. Is 5 mol% or less, preferably 0.
It is 5 mol% or more and 3 mol% or less, and in the case of a tetrafunctional component, it is 3 mol% or less, preferably 0.2 mol% or more and 2 mol% or less.

If the proportion of the trifunctional component used is more than 5 mol%, or if the proportion of the tetrafunctional component used is more than 3 mol%, the risk of gelation during the esterification reaction increases significantly.

The synthesis of relatively high molecular weight polyester prepolymers requires the use of a deglycolization catalyst during the deglycolization reaction following esterification.

Examples of the deglycolization catalyst include acetoacetoyl type titanium chelate compounds and titanium compounds such as organic alkoxy titanium compounds.
These titanium compounds can be used in combination. Examples of these include diacetoacetoxyoxytitanium ("Narsem titanium" manufactured by Nippon Kagaku Sangyo Co., Ltd.), tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium and the like. The titanium compound is used in an amount of 0.001 to 100 parts by weight of the polyester prepolymer.
It is 1 part by weight, preferably 0.01 to 0.1 part by weight.
The titanium compound may be added from the beginning of esterification or immediately before the deglycolization reaction.

As a result, the polyester polymer or prepolymer usually has a number average molecular weight of 5,000 or more,
It is more preferable that those having a melting point of 60 ° C. or higher and a melting point of 10,000 or higher can be easily obtained and have crystallinity.

In order to obtain the aliphatic polyester resin of the present invention, a polyester prepolymer having a number average molecular weight of 5,000 or more, preferably 10,000 or more, whose terminal group is substantially a hydroxyl group, is further added. Coupling agents are used to increase the number average molecular weight.

Examples of the coupling agent include diisocyanate, oxazoline, diepoxy compound and acid anhydride, and diisocyanate is particularly preferable.

In the case of an oxazoline or diepoxy compound, it is necessary to react the hydroxyl group with an acid anhydride or the like to convert the terminal to a carboxyl group before using it as a coupling agent.

The diisocyanate is not particularly limited,
For example, the following types are listed. 2,4-tolylene diisocyanate, 2,4-tolylene diisocyanate and 2,
Mixture with 6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, especially hexa Methylene diisocyanate is preferable from the viewpoint of the hue of the resin produced, the reactivity when the polyester is added, and the like.

The amount of these coupling agents added is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the polyester prepolymer.

The addition is preferably carried out under the condition that the polyester prepolymer is in a uniform molten state and can be easily stirred. It is not impossible to add it to a solid polyester prepolymer and melt and mix it through an extruder, but add it to an aliphatic polyester production device or to a molten polyester prepolymer (for example, in a kneader). Is practical.

In this case, the aliphatic polyester has a number average molecular weight of 10,000 or more, which makes the polyester resin and the polyester resin composition have sufficient mechanical properties.

The aliphatic polyester resin thus obtained has a temperature of 190 ° C. and a shear rate of 100 (sec ⁻¹ ).
Has a melt viscosity of 1.0 × 10 ^{3 to} 1.0 × 10 ⁶ poise. Particularly preferably 1.0 × 10 ^{4 to} 5.0 ×
It is 10 ⁴ poise.

The melt viscosity was measured with a nozzle diameter of 1.0.
mm, using a nozzle of L / D = 10, resin temperature 1
Shear rate 100 sec from the relational graph between shear rate and apparent viscosity measured by capillary rheometer at 90 ° C
The viscosity at ^-1 was determined.

The aliphatic polyester resin is then processed into flakes or fibers, preferably fibers. In the case of using fibers, it is convenient to use as short fibers having a length substantially equal to that of the cellulosic fibers for mixing and mixing with the cellulosic fibers.

In the present invention, in order to produce a pulp board as shown in FIG. 1, both flakes or fibers of cellulosic and aliphatic polyester resins are dispersed as they are or in water containing a small amount of a papermaking binder,
Papermaking is performed, and if necessary, a plurality of papermaking wet webs are stacked, pressed, compressed, and dried to obtain a pulp board. The thickness after drying varies depending on the purpose and application, but is about 1.0 to 30 mm for insulation boards, and about 0.5 to 10 for semi-hard boards, hard boards, etc.
mm, about 0.5 to 50 m for particle board
It is about m.

In this case, in the case of pressurized and dried pulp board, the melting point of the aliphatic polyester resin (varies depending on the type of the raw material aliphatic dibasic acid and glycol, the degree of polymerization, the type and amount of the coupling agent used). Is 90-1
It is in the range of 20 ° C. ) The following temperature, for example 80-90
Press and dry at a temperature up to about ℃.

In order to manufacture the pulp board as shown in FIG. 1, the above-mentioned wet method is preferable, but it may be manufactured by a dry method. When the pulp board is produced by a dry method, it is sufficient to press at a temperature of 80 ° C. or less and 10 to 30 kg / cm ² , and it is not particularly necessary to dry.

In the present invention, in order to produce a mere flat-plate pulp board by a wet method, a paper-made wet web is passed through a nip roller to squeeze water, cut into a desired size, pressurized and dried. good.

The pressing pressure is 10 to 20 kg / cm ² , and the pressing temperature is preferably 80 ° C. or lower.

In the case of partially heating and fusing as shown in FIGS. 3 and 4, it is necessary to heat and press at a heating temperature higher than the melting point of the aliphatic polyester resin, and as shown in FIG. It is preferable to use a pressed or pressure-dried pulp board, but when heat fusion is performed on the entire surface as shown in FIG. 2, the papermaking wet web is directly heated to a temperature not lower than the melting point of the aliphatic polyester resin. The heating method is preferable because the number of steps can be reduced.

Further, a solution or a melt of the biodegradable aliphatic polyester resin is coated on one side or both sides of the pressed or pressure-dried pulp board or the heat-fused pulp board, or the polyester resin. It is also possible to use a pulp board in which films are laminated by dry lamination.

In the present invention, when the pressured or pressure-dried pulp board and the completely fused pulp board are further processed (shaped), the pressure is the use of the aliphatic polyester resin. Inversely proportional to quantity. Generally, the pressure is 10 to 30 kg / cm ² , and it is preferable to press at a temperature not lower than the melting point of the aliphatic polyester resin.

From the pressed or pressure-dried pulp board and the completely fused pulp board, a shallow-drawing tray, a dish, and a deep-drawing container are formed by secondary forming by hot pressing. However, in order to manufacture a deep-drawing container, it is preferable to preform the wet web after paper making into a container shape in advance and dry it to obtain a container of good quality. Further, this container may be further hot pressed.

By hot pressing, a molded product having a surface with excellent smoothness can be obtained. Press pressure is 1
The press temperature is 0 to 30 kg / cm ² , and the pressing temperature is not lower than the melting point of the aliphatic polyester resin.

When manufacturing a deep-drawing container, a deep-drawing ratio (depth / caliber) of about 1 at maximum is suitable.

Cellulosic flakes or fibers 50-9
0 to 10% by weight of biodegradable aliphatic polyester resin flakes or fibers 50 to 10% by weight (total 100
% By weight). When the polyester resin content exceeds 50% by weight, the resulting pulp board has low rigidity. On the other hand, when the amount is less than 10% by weight, not only deep drawing cannot be performed, but also the fusion bondability by thermocompression bonding deteriorates.

The pulp board of the present invention is used as a soundproofing material, cushioning material,
When used as a heat insulating material, the amount of flakes or fibers of the aliphatic polyester resin is preferably in the range of 10 to 30% by weight.

The pulp board thus obtained has a specific gravity of 0.4 or less as an inflation board, 0.4 to 0.8 as a semi-hard board, and 0.8 or more as a hard board or particle board. It is possible to freely produce a pulp board that is highly breathable and completely impermeable to air.

[0050]

The conventional fiber board or particle board uses a prepolymer of a thermosetting resin which does not biodegrade when no binder is used or when it is used. Deep drawing by hot press could not be performed. The biodegradability was also significantly impaired. A feature of the present invention is that flakes or fibers of a biodegradable aliphatic polyester resin are used as a binder together with a cellulosic material as a constituent material of this board. Therefore, it is possible to exert the biodegradability and excellent rigidity and other mechanical properties of the cellulosic material without losing the properties, and the elasticity, thermoplasticity (deep drawing processability) and melting by thermocompression of the aliphatic polyester resin. , The formation of boards by fusion, etc. could be given the performance which was not possible with simple fiber boards.

[0051]

The present invention will be described in more detail with reference to the following examples.

(Synthesis Example 1) A 700 L reactor was purged with nitrogen, and then 183 kg of 1,4-butanediol and 224 kg of succinic acid were charged. The temperature was raised in a nitrogen stream, and the esterification reaction by dehydration condensation was carried out for 3.5 hours at 192 to 220 ° C. for 3.5 hours, and then nitrogen was stopped for 3.5 hours under a reduced pressure of 20 to 2 mmHg. The sample collected had an acid value of 9.2 mg / g, a number average molecular weight (Mn) of 5,160, and a weight average molecular weight (Mw) of 10,67.
It was 0. Subsequently, 34 g of tetraisopropoxytitanium as a catalyst was added under a nitrogen stream under normal pressure. Raise the temperature to 15 ~ 0.2mmHg at 215 ~ 220 ℃
The deglycolization reaction was performed for 5.5 hours under reduced pressure. The sample collected had a number average molecular weight (Mn) of 16,800 and a weight average molecular weight (Mw) of 43,600. The yield of this polyester (A1) is 339 when condensed water is removed.
It was kg.

5420 g of hexamethylene diisocyanate was added to a reactor containing 339 kg of polyester (A1), and a coupling reaction was carried out at 180 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelation occurred. Next, 1700 g of Irganox 1010 (manufactured by Ciba Geigy) as an antioxidant and 1700 g of calcium stearate as a lubricant were added, and stirring was continued for another 30 minutes. This reaction product was extruded into water with an extruder and cut into pellets with a cutter. 90 ° C
The yield of polyester (B1) after vacuum drying for 6 hours was 300 kg.

The obtained polyester (B1) is a slightly ivory white waxy crystal having a melting point of 110.
C., the number average molecular weight (Mn) is 35,500, the weight average molecular weight (Mw) is 170,000, the MFR (190 ° C.) is 1.0 g / 10 minutes, the viscosity of a 10% solution of orthochlorophenol is 230 poises, Temperature 190 ℃, shear rate 10
The melt viscosity at ⁰ sec ⁻¹ was 1.5 × 10 ⁴ poise. The average molecular weight is measured by Shodex GPC.
System-11, the solvent is a solution of CF ₃ COONa in 5 mmol hexafluoroisopropyl alcohol, the concentration is 0.1% by weight, and the calibration curve is Showa Denko KK's PMMA standard sample Shodex Standard M-75.
I went there.

(Synthesis Example 2) A 700 L reactor was purged with nitrogen, and then 177 kg of 1,4-butanediol, 198 kg of succinic acid, and 25 kg of adipic acid were charged. The temperature is raised under a nitrogen stream and the temperature is set at 190 to 210 ° C for 3.5 hours.
Further stop the nitrogen, and under a reduced pressure of 20-2 mmHg 3.5.
The esterification reaction by dehydration condensation was performed over time.
The sample collected had an acid value of 9.6 mg / g, a number average molecular weight (Mn) of 6,100, and a weight average molecular weight (Mw).
Was 12,200. Subsequently, 20 g of tetraisopropoxytitanium as a catalyst was added under a nitrogen stream under normal pressure. Raise the temperature to 15-
The deglycol reaction was performed for 6.5 hours under a reduced pressure of 0.2 mmHg. The collected sample has a number average molecular weight (Mn)
Is 17,300, and the weight average molecular weight (Mw) is 46,
It was 400. The yield of this polyester (A2) was 337 kg when condensed water was removed.

4.66 kg of hexamethylene diisocyanate was added to a reactor containing 333 kg of polyester (A2), and a coupling reaction was carried out at 180 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelation occurred. Next, 1.70 kg of Irganox 1010 (manufactured by Ciba Geigy) as an antioxidant and 1.70 kg of calcium stearate as a lubricant were added, and stirring was continued for another 30 minutes. This reaction product was extruded into water with an extruder and cut into pellets with a cutter. 9
Polyester (B2) after vacuum drying at 0 ° C for 6 hours
The yield was 300 kg.

The polyester (B2) obtained was a slightly ivory white waxy crystal and had a melting point of 103.
° C, number average molecular weight (Mn) is 36,000, weight average molecular weight (Mw) is 200,900, MFR (190 ° C) is 0.52 g / 10 minutes, 10% of orthochlorophenol.
Viscosity of the solution is 680 poise, temperature 190 ℃, shear rate 1
The melt viscosity at 00 sec ⁻¹ was 2.2 × 10 ⁴ poise.

(Example 1) The polyester (B1) obtained in Synthesis Example 1 was extruded from a nozzle at a molding temperature of 230 ° C.
It was cooled and solidified in a water tank at 30 ° C. and then stretched to produce a multifilament having a single yarn fineness of 5 denier. The obtained multifilament was cut into a length of 5 mm to obtain a staple fiber.

A mixture of 40% by weight of the above staple fibers and 60% by weight of wood pulp fibers has a thickness of about 1.5 m.
A wet sheet of m was obtained. This wet sheet vertically 1
After preforming into a container of 6 cm × width 8 cm × depth 5 cm and drying, it is loaded in the same mold of the hot press and pressed at a mold temperature of 115 ° C and a pressure of 20 Kg / cm ² for about 45 seconds to form a lunch box shape. The food container of was produced. The molded body was taken out of the mold, left to cool in air, and the container had a wall thickness of about 1 mm and a flexural modulus of about 28,000 Kg / cm ² .

Further, when this molded body was buried in soil for 5 months, the shape as the original container was not left.

(Example 2) The polyester (B2) obtained in Synthesis Example 2 was extruded from a nozzle at a molding temperature of 230 ° C,
It was cooled and solidified in a water tank at 30 ° C. to produce a multifilament having a single yarn fineness of 8 denier. The obtained multifilament was cut into a length of 5 mm to obtain a staple fiber.

A wet sheet was obtained by mixing 30% by weight of the above staple fibers and 70% by weight of wood pulp fibers. The wet sheet was sandwiched between nip rolls to squeeze the water in the wet sheet and then dried with heated air at 60 ° C. to obtain a pulp board having a thickness of about 5 mm (pulp board 1).

Then, the pulp board 1 is heated to a temperature of 110.
The pulp board was heat-pressed at 25 ° C. and a pressure of 25 Kg / cm ² to produce a pulp board having a thickness of 3.2 mm in which the entire surface of the pulp board was fused (pulp board 2). The flexural modulus of this fused pulp board 2 was about 23,000 Kg / cm ² .

When the fused pulp board 2 was buried in soil for 5 months, the original pulp board 2 had no shape.

(Example 3) On one side of the pulp boards 1 and 2 obtained in Example 2, a biodegradable aliphatic polyester resin (trade name: Bionore, density = 1.3, MFR
= 20 g / 10 min (190 ° C.), melting point 119 ° C.) 65 mmφ extruder (L / D = 28, compression ratio = 3.2)
Was extrusion laminated from a 1,200 mm wide T-die. The extruder head pressure is 220 kg / cm ² , the resin temperature is 193 ° C., and the laminate thickness is pulp board 1.
(Main body thickness 5 mm) was 80 μ, and pulp board 2 (main body thickness 3.2 mm) was 22 μ. The tensile breaking strength of the laminated pulp board 1 is 420 kg / cm.
² , the flexural modulus was 2100 Kg / cm ² , and the water vapor permeability was 800 g / m ² , 24 hours. Similarly, the pulp board 2 has a breaking strength of 750 Kg / cm ² and a flexural modulus of 2
9,600Kg / cm ² , water vapor transmission rate is 650g / m
It was ² , 24 hours.

[0066]

The biodegradable aliphatic polyester resin used in the pulp board of the present invention comprises glycol as a raw material,
The melting point of the resin can be freely adjusted within a range of about 90 to 120 ° C. according to the purpose of use by changing the types of the aliphatic dibasic acid and the polyfunctional component, the degree of polymerization of the polyester prepolymer, and the type and amount of the coupling agent. It is possible to set, and it is easy to manufacture flakes or fibers by using it, and it is also easy to manufacture pulp board by mixing it with cellulosic flakes or fibers. In particular, the density of the aliphatic polyester resin is appropriate, and mixing with wood pulp or the like can be easily performed.

Further, by changing the mixing ratio of the cellulosic flakes or fibers and the polyester resin, and further selecting the degree of fusion, fiberboard to particleboard can be freely manufactured.

In particular, the air permeability can be freely produced from a pulp board that is simply pressurized and has extremely high air permeability to a completely non-air permeable board that is pressed under heating conditions above the melting point of the polyester resin.

Further, the water vapor transmission rate of the polyester resin is much larger than that of the polyolefin resin and the like.
1,000 g · 30 μm / m ² , 24H and cellulose film (2,000 to 4,000 g · 30 μm / m ² ,
24H) and has breathing of water vapor even when coated or laminated.

Thus, even when the pulp board itself or the surface of the pulp board is coated with the polyester resin or laminated with a film of the resin, it has the biodegradability which is a feature of the present invention.
Even so, the goal is to be able to produce as large a board as the paper machine allows.

When a resin having heat resistance is used for this pulp board, the molded product can withstand boiling and steam heating, and therefore can be used as a food container which can be sterilized, cooked and the like.

The amount of polyester resin fiber blended is 30
% Or less, it can be effectively used as a soundproofing material, a heat insulating material, a cushioning material and the like.

Particularly, the pulp board of the present invention, which comprises 30% by weight or less of polyester resin and pulp, in which the polyester resin is completely melted, is a pulp board in which the fibers of pulp are reinforced with biodegradable aliphatic polyester resin. A particleboard-like pulp board which is in the form of fibers and which can be subjected to secondary processing having high mechanical properties, particularly toughness, is obtained.

[Brief description of drawings]

FIG. 1 Pulp board of the present invention simply pressed or pressure-dried.

FIG. 2 is a pulp board of the present invention which is entirely thermocompression bonded.

FIG. 3 is a partially heat-pressed pulp board of the present invention.

FIG. 4 is a pulp board of the present invention partially thermocompressed.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location D04H 1/54 A 7199-3B D21H 27/36 17/53 13/24 D21J 3/00 7199-3B 7199-3B D21H 5/20 E

Claims (7)

[Claims] 1. Cellulosic flakes or fibers
A pulp board comprising a mixture of 0 to 90% by weight and 50 to 10% by weight of flakes or fibers of a biodegradable aliphatic polyester resin, which is pressed or pressure-dried. 2. A pulp board obtained by partially or wholly heating and pressing the pulp board according to claim 1 to melt and fuse the biodegradable aliphatic polyester resin. 3. A laminated pulp board, characterized in that one side or both sides of the pulp board according to claim 1 or 2 is coated with a biodegradable aliphatic polyester resin, or a film of the resin is laminated. . 4. A biodegradable aliphatic polyester resin,
A number average molecular weight synthesized from glycol and an aliphatic dibasic acid or its derivative is at least 10,000.
The pulp board according to claims 1 to 3, which is an aliphatic polyester having 0. 5. A method for producing a pulp board, which comprises mixing and mixing cellulosic flakes or fibers dispersed in water with flakes or fibers of a biodegradable aliphatic polyester resin, and compressing and drying them. 6. Cellulosic flakes or fibers 50.
Of 90 to 90% by weight and flakes or fibers of a biodegradable aliphatic polyester resin in an amount of 50 to 10% by weight are preformed into a container-like wet web and dried to form a biodegradable mold. body. 7. A biodegradable molded article obtained by hot pressing the biodegradable container according to claim 6.