JPS6347600B2 - - Google Patents

Description

[Detailed description of the invention]

It is an object of the present invention to provide a die board for paper carton punching that has excellent dimensional stability, can be punched out many times per hour, has a long lifespan of punching, and can have a punching blade replaced many times, and is strong and lightweight. It is something. Conventionally, the die board for paper carton punching uses plywood approximately 18 mm thick, which is formed from orthogonal Chinese veneer. However, in the case of plywood, the punching dimensions vary due to variations in raw wood and large dimensional changes due to changes in atmospheric conditions (temperature, humidity) during use, which limits the number of punches that can be punched per hour. ,
Furthermore, since the plywood is soft, there is a drawback that the number of punching lifetimes and the number of times the blade can be replaced is limited. Recently, materials stronger than conventional paper, such as rubber, plastic, asbestos boards, paper laminates, and paper-plastic laminates, are sometimes punched out. In addition, these strong materials can be used for items that require dimensional accuracy to prevent water leakage, such as water containers such as milk cartons and alcohol cartons, or for conventional cardboard boxes such as packaging containers for precision electrical and electronic parts. There are times when we punch out items that require much higher dimensional accuracy than cases. Furthermore, there are cases in which die boards for punching paper cartons are required to have greater dimensional stability, as electronic parts such as floppy disks are sometimes punched out that require a high degree of dimensional accuracy. On the other hand, paper carton punching machines have also improved, and previously they could cut 120 to 2,000 shots per hour.
Recent cutting machines made by Bobst (Switzerland) are capable of producing 3,000 to 15,000 shots per hour, and die boards for paper carton cutting are increasingly required to have dimensional stability and robustness for high-speed punching. It has become like that. The performance of conventional china veneer plywood is insufficient to meet this demand. In order to meet this demand, some molds are used for punching die boards, but this method has drawbacks such as being heavy, not versatile, and high cost. In addition, attempts were made to improve plywood by using lauan veneer, beech veneer, maple veneer, etc. other than China veneer, but the dimensional changes caused by changes in atmospheric conditions were large, and the number of punches that could be punched per hour was limited. There were drawbacks such as a limit to the number of times the blade could be replaced. As mentioned above, the reality is that no punching die board has ever been manufactured that is lightweight, inexpensive, and has excellent durability, robustness, and dimensional stability. The inventors have improved the drawbacks of china veneer plywood and molds, making it robust, having good dimensional stability, allowing for more punches per hour, and being lightweight, reducing the number of punching cycles and the number of blade replacements. We have been considering die boards that are often used for paper carton punching. As a result, it was discovered that a structure in which a synthetic resin is combined with a laminated cardboard obtained by heating and pressurizing two or more layers of paper pulp mat has excellent properties (Patent Application No. 57-
130371, patent application Sho-57-130372, patent application Sho-57-
130373, patent application Sho-58-45949). As a result of further investigation, we found a configuration with extremely good dimensional stability when using a die board. The present invention was invented as a result of studying various materials, and it has excellent dimensional stability, which allows for a large number of punches per hour. This relates to a die board for punching paper cartons that can be changed many times, is strong, and is lightweight. That is, laminated cardboard 6 to 0.5 to 2.6 mm thick obtained by heating and pressing two or more layers of paper pulp mats.
A die board material consisting of a laminate of 36 sheets pasted with resin, with a specific gravity in which at least the inside of the laminated cardboard contains 2 to 40% (by weight, the same applies hereinafter) of thermosetting resin. 1.1~1.5, thickness 15~
The die board for paper carton punching, which is 19 mm in diameter and has a volatile content of 3.5 to 0%, has much better dimensional stability than the cardboard laminated die board that the inventors have been researching. I found that it is suitable for a die board. In the present invention, the pulp used for the laminated cardboard may be ordinary pulp, but among these, a mixture of kraft pulp and kraft linter pulp is preferable, and if a mixture of these and waste paper pulp is used, strength and dimensional stability can be improved. A die board with excellent durability and durability can be obtained. Among kraft pulps, thick and long pulps obtained from coniferous trees are good, and among these, kraft pulps obtained from red pine, black pine, etc. are the best. The laminated cardboard that can be used in the present invention is obtained by paper-making the above-mentioned pulps so that they are intertwined, and then laminating two or more layers of pulp while wet with water under heat and pressure in a conventional manner.
Furthermore, in order to obtain multi-layered laminated cardboard, multiple pulp mats are wound around a drum, or they are placed in a predetermined case and dried appropriately using a conventional method, and then laminated under pressure and heat using a press. If the obtained cardboard is used, a die board with excellent strength and dimensional stability and good durability can be obtained. The pulp mat may have two or more layers, but preferably eight or more layers. Among these laminated cardboards, pressboard is particularly suitable as a dieboard material because it has excellent dimensional stability and strength. Even in these pressboards, the volatile content
If 3.5 to 0% is used, the dimensional stability is very good, and especially if 1 to 0% is used, the dimensional stability is very good. Examples of pressboard are JIS C2305 (1966), B S-231 (1967),
Among those that correspond to standards such as DIN-7733 (1962) and ASTM D-1305 (1973), volatile content of 3.5 to 0%,
Preferably it is 1 to 0%. When making these laminated cardboards, additives that are normally added when making paper are added, or inorganic base materials, organic base materials,
Alternatively, such fibers or fillers can be added. It is also possible to color laminated cardboard. As the resin contained in the laminated cardboard of the present invention, a thermosetting resin is used in order to obtain a die board for paper carton punching that has good dimensional stability and can be punched out many times per hour. However, in order to obtain a die board for paper carton punching that has better dimensional stability and can be punched out more times per hour, the heat distortion temperature is 60℃.
(ASTM D-648), thermal expansion coefficient is 20×10 ^-5
(ASTM P-696) thermosetting resins are preferred. Unsaturated polyester resins and epoxy resins are suitable resins if the reinforcement of the laminated cardboard, dimensional stability, and number of punches per hour are taken into account. The amount of resin contained in the laminated cardboard is preferably 2 to 40%, preferably 5 to 30%.
If it is less than 2%, no effect of imparting dimensional stability can be expected, and if it is more than 40%, the cost will increase. Methods for incorporating resin include dissolving the resin in water during pulp mat papermaking, or finely crushing it into 8 or more meshes and dispersing it in water to obtain pulp mat, and laminating two or more layers of this, and a method in which the resin is laminated in two or more layers. There is a method in which cardboard obtained by laminating multiple layers is coated, impregnated, or immersed. When performing coating impregnation or dipping impregnation, in the case of liquid resin, there are two methods: using it as it is, and dissolving the liquid resin in water or a solvent such as alcohol, ketone, aromatic, ester, etc., or a mixture thereof, or emulsifying it. use. In the case of solid resin, like liquid resin, it is used by dissolving it in water or an organic solvent. When the thermosetting resin 2 is contained inside the laminated cardboard 1 of the surface layer as shown in FIG. 3, it is preferably 1 to 30%. In this case, the same resin as the resin 3 normally used for coating and impregnating or pasting is impregnated under pressure. The thickness of the laminated cardboard is preferably 0.5 to 2.6 mm. If it is less than 0.5 mm, the cost will be high, and if it is more than 2.6 mm, it will not be possible to obtain a paper carton die board with good dimensional stability even if it contains a thermosetting resin and is attached with resin. The resin for pasting the laminated cardboard used in the present invention can be selected arbitrarily because the laminated cardboard is reinforced with a thermosetting resin that has good dimensional stability. In order to obtain resin properties, in terms of dimensional stability, heat distortion temperature is 60℃ or higher (ASTM D-648), and thermal expansion coefficient is 60℃ or higher (ASTM D-648).
In terms of ^strength , the bending strength is preferably 5 kg/mm ² or more (JIS-K-6911). Among these, good thermosetting resins are melamine resin, urea resin, epoxy resin, and unsaturated polyester resin, and good thermoplastic resins are polyvinyl alcohol, vinyl acetate resin, and vinyl acetate copolymer resin.
Modifications and mixtures of these resins may also be used.
In addition, tackifiers, plasticizers, softeners,
fillers, waxes, antioxidants, other additives,
etc. can also be added. Methods for using this resin include a method in which it is applied directly to laminated cardboard, or a method in which it is impregnated or applied to a sheet-like fibrous base material and thereby the laminated cardboard is attached. In the former method, the amount of resin is 1 on the adhesive side of the cardboard.
1 to 500 g per square meter is good, preferably 4 to 300 g. If it is less than 1g, it will not be able to stick well, and if it is more than 500g, the cost will be high.
Resin is wasted. In the latter method, paper,
Impregnating or coating cloth, nonwoven fabric, glass fiber cloth, etc. with resin. The amount of resin per 100 parts (parts by weight, same hereinafter) of this fibrous base material is preferably 30 to 200 parts; if it is less than 30 parts, sufficient adhesion cannot be obtained, and if it is more than 200 parts, the cost will be high. The thickness of the fibrous base material containing the resin to be adhered is preferably 0.05 to 0.5 mm; if it is less than 0.05 mm, sufficient adhesion and dimensional stability cannot be obtained;
Above that, the cost will be high. Furthermore, there is a method of using resin in sheet form, but this method uses sheets with a thickness of 9 μm or more.
0.4 mm is good, preferably 30 μm to 0.2 mm. If it is less than 9μ, sufficient adhesion cannot be obtained, and if it is more than 0.4mm, the cost will be high. The volatile content of the die board of the present invention is 300mm x 300mm x
When a test piece with a large thickness is dried at 150° C. for 3 hours, a good range is 3.5 to 0%, and a range with the best dimensional stability is 1 to 0%. Volatile content 3.5% or more15
% or less, it has much better dimensional stability and robustness than China veneer plywood, but in the range of 3.5 to 0
%, even if 500,000 shots are continuously punched, the dimensional stability is very good, and the number of punches per hour is large, and at 1 to 0%, there is almost no dimensional change. The specific gravity of the paper carton punching die board of the present invention is 1.1~
1.5 is good. If the specific gravity is less than 1.1, the desired dimensional stability cannot be obtained, and if it exceeds 1.5, it will be heavy and impractical, and furthermore, it will be difficult to process the die board and increase the cost. The thickness of the die board of the present invention is preferably 15 to 19 mm.
If it is less than 15mm, it is difficult to fix the punching blade or folding blade.
If it is 19 mm or more, the rubber or spring for taking out the punched material cannot be used effectively. As a method for obtaining a paper carton die board with a volatile content of 3.5 to 0% according to the present invention, a volatile content of 3.5% containing a thermosetting resin obtained by heating and pressing two or more layers of paper pulp mats is 2 to 40%. There are two methods: using laminated cardboard that has been dried to ~0%, and laminating cardboard obtained by heating and pressing two or more layers of paper pulp mat with a resin containing 2 to 40% thermosetting resin. When putting on clothes, there is a method of applying pressure while heating and drying. In order to obtain a laminated cardboard with a volatile content of 3.5 to 0% containing a thermosetting resin of 2 to 40%, a method of coating or dipping the laminated cardboard with a volatile content of 3.5 to 0% and applying a thermosetting resin; There are a method of drying a laminated cardboard into which a thermosetting resin has been incorporated during paper making, and a method of drying a laminated cardboard after containing a thermosetting resin, and these methods can also be combined. The structure of the present invention is as follows: (a) As shown in FIG. 1, a laminated cardboard 1 containing 2 to 40% thermosetting resin is pasted with resin 2; (b) As shown in FIG. A laminated cardboard 3 containing no thermosetting resin constituting the surface layer and a laminated cardboard 1 containing 2 to 40% of thermosetting resin are pasted together with resin 2, as shown in (c) in Fig. 3. Like,
Laminated cardboard 4 containing 1 to 30% thermosetting resin on the inside and 2 to 40% thermosetting resin constituting the surface layer.
(d) As shown in FIG. 4, the surface (both sides) of the structure of (a) is coated with synthetic resin 5 or thermoset It is coated with a 0.05 to 0.5 mm fibrous base sheet 5 containing a synthetic resin. When a paper carton die board having the structure shown in FIGS. 1 and 4 is created, the surface can be matted or roughened to facilitate the attachment of rubber for taking out the punched product. In the case of Figures 1 to 4, the thermosetting resin is
The lamination of the laminated cardboard containing 40% can be made in the same direction, or in the orthogonal direction, or in part in the same direction and in part in the orthogonal direction. When laminated cardboard containing thermosetting resin is pasted with resin, the paper is assembled and laminated as shown in each figure. The lamination method is pressurized lamination by a conventional method such as a press molding method or a block lamination method. In this case, the pressure applied to the laminate is preferably 50,100 kg/cm ² , and the pressing time and temperature may be conditions suitable for the resin used, the thermosetting resin contained in the laminated cardboard, and the lamination method. The above-mentioned sticky die board material for paper carton punching is processed by mechanical methods such as sawing, cutting, and drilling, thermal methods such as carbon dioxide laser, or hydraulic processing such as Aquajet to create groove widths for inserting cutting blades. Machining grooves of 0.7±0.05mm, 0.9±0.05mm, etc. A punching blade having a predetermined thickness is inserted into this groove. When punching paper such as kraft paper, cardboard, cardboard, linter paper, rubber, plastic, asbestos, board, paper plastic laminate products, paper adhesive plastic laminate products, etc., use the conventional die board for punching paper cartons made of plywood plywood. In comparison, the paper carton die board of the present invention has extremely good dimensional stability, can be punched out many times per hour, has excellent robustness and durability, and is lightweight. Examples will be shown below. Comparative example 1 Ten Chinese veneers of approximately 1.85 mm were arranged orthogonally,
A die board material for punching paper cartons made of 17.9 mm Chinese veneer plywood was obtained by pressure-heat molding and sanding using a urea adhesive and a normal plywood manufacturing method. Comparative Example 2 Eight polyurethane sheets were inserted between nine sheets of 48-layer laminated cardboard thicker than 1.9 mm made of kraft/linter mixed paper, and pressed using a press.
Heat and pressurize at 140℃, 15Kg/cm ² for 60 minutes, then heat at the same pressure for 15 minutes.
Cool for minutes to a thickness of 18.2 mm (approx. 1.7 mm thick paper, approx. 0.3 mm)
A die board material for paper carton punching with a specific gravity of 1.15 and a volatile content of 7% was obtained. Example 1 A press board with a thickness of approximately 1.6 mm that complies with JIS C2305 (1966) was dried at 130°C for 50 minutes to remove volatile matter.
0.1% or less, unsaturated polyester resin, RT-
10 parts of 400 (manufactured by Mitsui Toatsu, base resin for low shrinkage) and R
-372 (manufactured by Mitsui Toatsu) and 1 part of BPO paste were immersed in a liquid resin for 48 hours at room temperature to obtain a laminated cardboard containing 23% resin. On the other hand, 57 parts of diallyl phthalate prepolymer, 3 parts of diallyl phthalate monomer, unsaturated polyester resin (R-
372) Polyester modified diallyl phthalate resin solution prepared by dissolving 40 parts of BPO paste, 2 parts of BPO paste, and 0.5 parts of calcium laurate in 100 parts of acetone was added to 200 m2 of polyester modified diallyl phthalate resin solution.
A prepreg with a resin content of 50% was obtained by impregnating kraft paper (g) with the resin and drying it at 100°C for 10 minutes. The 210 sheets of prepreg and the 111 sheets of laminated cardboard were assembled into the configuration shown in Figure 1, and heated at 140°C for 40 minutes using a press.
Kg,/cm ² for 60 minutes and cooled for 30 minutes at the same pressure to obtain a die board material for paper carton punching having a thickness of 17.0 mm, a specific gravity of 1.42, and a volatile content of 0.1% or less. Example 2 A press board with a thickness of about 2 mm that complies with JIS C2305 (1966) was mixed with 100 parts of epoxy resin EP-1001 (manufactured by Ciel Chemical) and 9 parts of 4,4'diaminodiphenylmethane.
200 parts of acetone at room temperature for 4 hours, and dried at 60°C for 1 hour to reduce the resin content to 16.
A laminated cardboard with a volatile content of 5.5% was obtained. A varnish made by dissolving 100 parts of epoxy resin Ep-1001 and 12 parts of 4,4'diaminodiphenylmethane in 100 parts of methyl ethyl ketone was impregnated into a glass cloth with a weight of 166 g, which corresponds to JIS R3414 (ES-13), and heated to 110℃ for 5 minutes.
After drying for 30 minutes, a prepreg with a resin content of 55% was obtained. The 10 sheets of prepreg 2 and 5 and the 19 sheets of laminated cardboard were assembled alternately so that the papermaking direction of each sheet of laminated cardboard was perpendicular to each other, and the structure shown in FIG.
The material was heated and pressurized at Kg/cm ² for 120 minutes and cooled at the same pressure for 15 minutes to obtain a paper carton die board material having a thickness of 17.8 mm, a volatile content of 3.2%, and a specific gravity of 1.27. The die board materials obtained in Examples and Comparative Examples were grooved using a carbon dioxide laser and router processing, a punching blade was embedded therein, and a rubber spring was attached to create a die board for paper carton punching. A 1000ml water container was created by punching out 1.0mm thick liquid pack paper that had been waterproofed with resin using a print-linked punching machine manufactured by Swiss Bobst.
The number of punching cycles per hour, the number of punching cycles, and the number of times the blade can be replaced were measured. As shown in Table 1, compared to the china veneer plywood that was conventionally used as a cutting die,
Due to its good dimensional stability, the number of punches per hour can be approximately tripled, and the number of times the punching blade can be used for punching and the number of times the punching blade can be replaced is also quite large. In addition, since it has better dimensional stability than a laminated board with a volatile content of 7%, the number of punches per hour can be doubled.
Furthermore, in Example 1, the dimensional change during punching of 500,000 shots was ±0.02 since the volatile content was less than 0.1%.
%, which was very good.

【table】

[Table] Comparative example 3 1.5 corresponding to press board DIN-7733 (1962)
An ethylene-vinyl acetate copolymer resin sheet of approximately 0.1 mm was placed as an adhesive film between each of the 12 sheets thicker than 1 mm, and heated at 140°C using a press.
The material was heated and pressurized at 50 kg/cm ² for 30 minutes, and then cooled at the same pressure for 20 minutes to obtain a die board material for paper carton punching having a thickness of 18.1 mm, a specific gravity of 1.2, and a volatile content of 7%. Comparative Example 4 100 parts of unsaturated polyester M-2101 (manufactured by Mitsui Toatsu) and 1 part of BPD paste were added to a press board with a thickness of approximately 1.7 mm that corresponds to JIS C2305 (1966) in acetone.
Apply 10 parts of resin solution with a roller and apply 40 parts of resin solution.
It was dried at ℃ for 10 minutes to obtain a laminated cardboard containing 12% resin content. On the other hand, 130 g of kraft paper was impregnated with the polyester modified diallyl phthalate resin liquid used in Example 1, and dried at 100°C for 10 minutes to reduce the amount of resin.
50% prepreg was obtained. The 9 sheets of laminated cardboard and the 10 sheets of prepreg were laminated alternately, and the layers were coated on both surfaces.
Two sheets of 0.8 mm thick pressboard conforming to JIS C2305 (1966) were assembled into the configuration shown in Figure 2, and heated under pressure at 140°C and 20 kg/cm ² for 60 minutes using a press machine.
A die board material for paper carton punching with a diameter of 17.4 mm, a specific gravity of 1.30, and a volatile content of 4.0% was obtained. Example 3 100 parts of epoxy resin Ep-1001 (manufactured by Ciel Chemical),
9 parts of 4,4' diaminodiphenylmethane and 1 part of calcium stearate are kneaded with two rolls, crushed with an atomizer mill, and sieved to a fine powder of 100 mesh or more, which is dispersed in water during Akamatsu pulp papermaking to form pulp. Contains 12% paper and consists of 48 layers.
A laminated cardboard thicker than 1.5 mm was obtained. 1 at 60℃
It was dried under reduced pressure of 20 mmHg for a period of time to reduce the volatile content to 0.4% or less. Press board that corresponds to JIS C2305 approximately 1.6
100 parts of Ep-1001 and 9 parts of 4,4' diaminodiphenylmethane were dissolved in 100 parts of acetone and applied with a roller to the inside of the 100 mm, and dried at 60℃ for 20 minutes to obtain cardboard containing 8% resin content. Ta. This is heated to 20mm for 1 hour at 60℃.
It was dried under reduced pressure of Hg to reduce the volatile content to 0.4% or less.
110 sheets of resin-filled laminated cardboard were assembled so that the papermaking directions were alternately perpendicular to each other, the prepreg 2 obtained in Example 2 was inserted between each sheet, and the inner resin-coated cardboard 4 was arranged on both surfaces. 140℃ with configuration as in 3.
The material was heated and pressurized at 50 kg/cm ² for 40 minutes and cooled at the same pressure for 20 minutes to obtain a die board material for paper carton punching having a thickness of 17.1 mm, a specific gravity of 1.38, and a volatile content of 0.2%. Example 4 Approximately 0.8 mm corresponding to ASTM-D-1305 (1973)
Unsaturated polyester resin on thick pressboard
PS-951 (manufactured by Dainippon Ink) 100 copies perg chill
1.5 parts of Z were mixed and coated on both sides using a roll coater. After 24 hours, both sides were coated, and again after 24 hours, both sides were coated to obtain a laminated cardboard containing 16% resin. Also, mix 100 parts of melamine/formaldehyde resin (methylol type) with 50 parts of methanol and water.
A 130 g kraft paper was impregnated with varnish dissolved in 50 parts of a mixed solvent and dried at 110°C for 10 minutes to obtain a prepreg with a resin content of 60%. Said laminated cardboard 1
22 sheets and the 223 prepreg sheets were alternately laminated,
The press board 3 with a thickness of about 0.5 mm is used as both surface layers, and the paper is assembled in the configuration shown in Figure 2, using a press machine.
Pressure and heat dry for 120 minutes at 130℃, 60Kg/cm ² intermittently for 10 minutes, then cool for 40 minutes at the same pressure to reduce thickness.
A die board material for paper carton punching with a diameter of 17.8 mm, a specific gravity of 1.32, and a volatile content of 2.8% was obtained. Die boards for punching were prepared by router processing the die board materials obtained in the Examples and Comparative Examples. The blade was embedded in this die board and cut to a thickness of 0.5 mm using a Swiss Bobst autoplaten type punching machine.
Cases of 20 cigarettes were punched out of kraft paper, and the dimensional stability, number of punches possible per hour, number of punching cycles of the punching blade, number of times the blade could be replaced, etc. were measured. As shown in Table 2, the number of punches that can be punched per hour is approximately three times that of the plywood plywood that was conventionally used as a cutting die, and the number of times that the punching blade can be used for punching and the number of times that the punching blade can be replaced is also considerably higher. Also, since it has better dimensional stability than a laminated board with a volatile content of 7%, the number of punches per hour can be approximately doubled. Furthermore, in Example 3, the dimensional change during punching of 100,000 shots was due to the volatile content being 0.2%.
It was very good, less than ±0.01%.

【table】

【table】 [Brief explanation of the drawing]

1 to 4 are cross-sectional views of die boards for punching paper cartons obtained according to examples of the present invention. 1... Laminated cardboard containing thermosetting resin, 2... Adhesive resin layer, 3... Laminated cardboard not containing resin, 4...
...Laminated cardboard containing thermosetting resin only on the inside,
5...Surface resin layer.

Claims (1)

[Scope of Claims] 1. 6 to 36 sheets of laminated cardboard with a thickness of 0.5 to 2.6 mm obtained by heating and pressing two or more layers of paper pulp mats and containing 2 to 40% of thermosetting resin. Specific gravity is 1.1~1.5, thickness is 15~
A paper carton die board with a diameter of 19 mm and a volatile content of 3.5% or less. 2. 4 to 34 sheets of laminated cardboard with a thickness of 0.5 to 2.6 mm obtained by heating and pressing two or more layers of paper pulp mats and containing 2 to 40% of thermosetting resin are used as the core material layer, and on both sides Same laminated cardboard that does not contain thermosetting resin is arranged as the surface layer, and resin is attached between each cardboard and the surface layer, specific gravity is 1.1 ~ 1.5, thickness is 15 ~
A paper carton die board with a diameter of 19 mm and a volatile content of 3.5% or less. 3 4 to 34 sheets of laminated cardboard with a thickness of 0.5 to 2.6 mm obtained by heating and pressing two or more layers of paper pulp mats and containing 2 to 40% of thermosetting resin are used as the core material layer, and on both sides , the same laminated cardboard containing 1 to 30% thermosetting resin on only one side is arranged as a surface layer with the side containing the thermosetting resin inside, and the space between each cardboard and the surface layer is covered with resin. The specific gravity is 1.1 to 1.5, the thickness is 15 to 19 mm, and the volatile content is 3.5.
% or less paper carton die board. 4 6 to 36 sheets of laminated cardboard with a thickness of 0.5 to 2.6 mm obtained by heating and pressing two or more layers of paper pulp mats and containing 2 to 40% of thermosetting resin are used as the core material layer, and on both sides , a sheet of fibrous base material coated with synthetic resin or containing thermosetting resin with a thickness of 0.05 to 0.5 mm is placed as the surface layer, and the space between each cardboard and the surface layer is bonded with resin, and the specific gravity is 1.1 to 1.5 mm, thickness is 15 to 19 mm, and paper carton die-cut die board with volatile content of 3.5% or less.