JP3363599B2 - High strength composite paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cardboard box for packaging, a partitioning material for packaging, a partition for a corrugated box, a partition for construction, and the like, which is a plate-shaped product for general industry, and particularly relates to a paper material requiring strength.

[0002]

2. Description of the Related Art Paper is often used for general industrial materials such as packaging materials and surface materials such as walls of houses as well as information recording and display materials and for construction. Recycled waste paper is often used for such industrial and construction purposes, which is preferable in terms of effective utilization of natural resources. However, such recycled waste paper has a short pulp fiber, which is a constituent material of the paper, and has a weak strength. For this reason, generally used is a method of mixing with a new long pulp fiber, or a method of thickening it to compensate for the strength reduction.

However, even with such a method, there is a limit in improving the strength, and it is difficult to develop it in a field requiring particularly strength, such as a partition core material for a house and an intermediate partition for packaging heavy goods. Further, generally, paper is apt to absorb moisture, and if moisture is absorbed, strength is reduced, and therefore it is difficult to use in an environment with a lot of water.

As one of the methods for solving these problems, there are means such as sticking paper with an adhesive to improve strength as thick paper, and sticking a thin resin film to take measures against moisture. However, even such a method has not completely solved the problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide higher strength, lighter weight and greater rigidity than conventional materials alone.
It is to provide a high-strength composite paper with excellent water resistance and durability.

[0006]

Means for Solving the Problems The present inventors have used paper as a core material and apply uniform tension to both front and back surfaces or one surface of the core material.
Reinforcing fibers aligned in one direction while pulling
Is contacted with molten thermoplastic resin and impregnated with resin
A prepreg obtained, which contains reinforcing fibers in a weight content of 40% or more and 80% or less and heats in a fiber direction.
It has been found that this can be achieved by laminating a prepreg having a coefficient of expansion of 10 ⁻⁵ / ° C. or less and a prepreg laminate (hereinafter referred to as a reinforcing layer) in which prepregs are laminated.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the high-strength composite paper according to the present invention, which shows the high-strength composite paper in which a reinforcing layer is attached to the surface of the paper. FIG. 2 shows a high-strength composite paper with a surface material attached thereto. FIG. 3 is a cross-sectional view showing a state in which an end portion is treated to prevent moisture absorption and water absorption. Figure 4
Shows an outline of an apparatus for integrating the reinforcing layer and the paper.

In FIG. 1, the thermoplastic resin constituting the reinforcing layers 12 and 13 is not particularly limited, and has a melting temperature at which the paper is not burnt at the temperature at which it is integrated with the paper and the paper does not deteriorate. For example, polystyrene, polyvinyl chloride, high density polyethylene, polypropylene, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyether sulfone, polysulfone, polyetherimide (trademark: ULTEM), polyetheretherketone, polyphenylene. Although sulfide can be used, polypropylene, polyethylene, and polystyrene resins are recommended as the most desirable resins from the viewpoints of strength, abrasion resistance, price, and ease of recycling when discarded. .

Examples of polypropylene resins include homopolymers of propylene, α of propylene and ethylene, butene, etc.
-In order to improve the adhesion between olefin copolymers and fibers and polypropylene resins, polypropylene resins are grafted with radically polymerizable unsaturated compounds such as maleic anhydride using an organic peroxide catalyst in a hydrocarbon solvent. An example is a polymerized grafted polypropylene resin.

As the polystyrene resin, a homopolymer of styrene, a copolymer of styrene and acrylonitrile, a polymer of butadiene and styrene, a polymer of acrylonitrile, and the like, and to improve adhesion to glass fiber, A grafted polystyrene resin obtained by graft-polymerizing a radically polymerizable unsaturated compound such as maleic anhydride with a polystyrene resin by using an organic peroxide catalyst in a hydrocarbon solvent can be mentioned.

As the polyethylene resin, HDPE,
LDPE, or a copolymer of ethylene and α-olefins, and a grafted polyethylene resin obtained by graft-polymerizing a radically polymerizable unsaturated compound such as maleic anhydride with a polyethylene resin in a hydrocarbon solvent with an organic peroxide catalyst are used. can give.

As the fibers to be added to the material of the reinforcing layers 12 and 13, synthetic resin fibers such as aramid fibers (registered trademark "Kepler"), natural organic fibers, titanium,
Examples thereof include metal fibers such as boron and stainless steel, and inorganic fibers such as glass, carbon and silicon carbide. Although glass fiber is particularly preferable, the glass fiber is not necessarily limited to these, and any one that has sufficient strength and is inexpensive and available in large quantities can be used.

Regarding the compounding ratio of this fiber in the reinforcing layer, if it is less than 40% by weight, the fluidity of the resin increases at high temperatures, which makes it difficult to shape the reinforcing layer and is necessary as a plate. Rigidity and abrasion resistance cannot be obtained. On the other hand, when it exceeds 80%, the adhesiveness is lowered and the molding process becomes difficult. Therefore, the blending ratio of fibers is 40% or more and 80% or less, preferably 45% or less. % To 60%.

When glass fibers are used as the fibers, mat-like or woven fabric-like ones are generally used because they are easy to handle and are lightweight, but in order to sufficiently exert the reinforcing effect, they are strong. Is required to be effectively utilized, and for that purpose, it is desirable to use a fiber reinforced resin in which fibers are aligned and arranged in one direction, that is, a prepreg is used. Further, it is recommended to provide a surface material such as a printing paper, a non-woven fabric such as felt, a woven fabric such as cloth, or a resin film on the surface of the reinforcing layer on the surface side in order to improve appearance and appearance. It is recommended that the fiber orientation be aligned with the direction in which it will undergo bending stress during use. It is also recommended to use this reinforcing layer as a laminate of a layer having fibers oriented in the width direction and a layer having fibers oriented in the longitudinal direction. The prepreg of the present invention is Japanese Patent Publication No. 02-042.
It can be manufactured by the method disclosed in Japanese Patent No. 168. That is, a monofilament of a reinforcing glass fiber is treated with a coupling agent, for example, γ-methacryloxy-propyltrimethoxysilane, and about 1800 converged yarns are aligned and heat-melted while being pulled with a uniform tension. It is obtained by contacting with a plastic resin and impregnating with a hot roll while squeezing.

This prepreg may be used as a single layer or as a stack of two or more layers. When the prepreg is laminated on one side of the paper, if the prepreg layer is thick, the coefficient of thermal expansion is large. In some cases, the composite plate warps. Therefore, the thickness of one layer of prepreg is 200 μm or less, and it is a supplementary layer in which two or more layers of prepreg are laminated.
The strong layer is preferably 1 mm or less. Further, since the double slip sheet is warped even if the thermal expansion coefficient of the prepreg is large,
The thermal expansion coefficient is preferably 10 ^-5 / ° C or less.

In FIG. 1, reference numeral 1 denotes a front surface and a back surface of a paper 11 on which reinforcing layers 12 and 13 composed of glass fibers aligned in one direction with a thermoplastic resin are laminated. The lamination of the paper and the reinforcing layer is achieved by placing the reinforcing layer in a molten state, which is heated to the melting temperature of the reinforcing layer or higher, on the paper and pressurizing it while cooling in the press. The pressure to be applied is preferably 3 kg / cm ² or less, and is 0.
01 kg / cm ² or more is preferable. Also, 0.1-3k
g / cm ² is more preferable. At this time, the molten thermoplastic resin of the reinforcing layer flows to the uneven portions of the lower paper on the surface of the paper, and then is cooled and solidified, so that the paper and the reinforcing layer are firmly bonded. Therefore, it is an effective method to preheat the paper to a temperature at which the resin can flow so that the resin flows and the uneven portions are filled with the paper. This temperature is preferably above the melting point of the thermoplastic resin and below the decomposition point, from the melting point to the melting point +50 to 1
00 ° C is more preferable. Resin does not flow below the melting point,
If it exceeds the decomposition point, the resin is decomposed and the desired physical properties cannot be obtained.

In addition, it is desirable to fuse the resin film to the surface of the paper in advance so that the resin film bites into the uneven portion of the paper surface in order to firmly bond the paper and the prepreg laminate. Alternatively, it is also an effective method to firmly integrate the reinforcing layer and the paper by interposing a resin film between the prepreg laminate in the molten state and the paper and performing simultaneous integral molding.

It is desirable that the resin film is the same as the resin constituting the reinforcing layer because of good compatibility. The resin film is compatible with the reinforcing layer when melted, and it is difficult for unevenness on the paper surface to enter, so
This is because strong adhesion between the reinforcing layer and the paper can be exhibited. According to the above method, the reinforcing layer is firmly attached to the surface of the paper without using an adhesive, so that the reinforcing effect can be obtained.

Reference numeral 10 in FIG. 2 denotes a surface material laminated on the surface of the high-strength composite paper 1. When the surface material 14 is used for a wall in a room, a partition, etc., a non-woven fabric or a woven fabric on which a pattern is printed, a printing paper on which a pattern such as wood grain is printed, or a wood-based thin plate is used as the surface material. You can Also,
When used outdoors, a resin film or equipment having excellent weather resistance can be used for the purpose of imparting weather resistance.

As a material for the surface material, a foamed or non-foamed sheet such as polypropylene or polystyrene, a thermoplastic resin product such as polyvinyl chloride or PZT sheet,
In addition to metal foils, woven fabrics and non-woven fabrics made of various fibers such as those having fibers exposed on the surface can be mentioned.

When this surface material is to be joined to the surface of the reinforcing layer by an adhesive, the thermoplastic resin in the reinforcing layer has a poor surface activity, so that the effect of the adhesive is reduced. Therefore, sanding the surface of the reinforcing layer, pretreatment such as corona discharge treatment, chemical etching, etc. are required, which causes an increase in cost. To solve this problem, it is effective to attach thick paper, non-woven fabric or the like on the reinforcing layer in advance as an auxiliary material for improving the adhesive strength at the time of melting.
Since the auxiliary material such as paper and non-woven fabric attached here has a function of impregnating and holding the adhesive, the surface material can be bonded by adhesion. That is, the auxiliary material is impregnated with an adhesive in order to improve the adhesive strength attached to the reinforcing layer, and the surface material is bonded thereto. The adhesive may be of any type such as an epoxy type and may be a thermoplastic type or a thermosetting type.

FIG. 3 shows an example of an end portion for preventing moisture absorption and water absorption of the high-strength composite paper. Reference numeral 16 denotes the back reinforcing layer 13 while the front reinforcing layer 11 is in a molten state. It is folded back and melted and integrated. Reference numeral 17 denotes a structure in which the front and back reinforcing layers 12 and 13 are melted and integrated while they are in a molten state.

FIG. 4 is a schematic diagram showing a method for producing a high-strength composite paper. Reference numeral 30 in FIG. 4 is a preheating device for preheating the prepreg of the reinforcing layer to give fluidity, and reference numeral 40 in FIG. 4 is a paper. This is an integrated device that integrates and cools the prepreg of the reinforcing layer during melting.

The paper usable in the present invention includes, but is not limited to, corrugated board, white paperboard, yellow paperboard, chipboard, colored paperboard, construction material paperboard, paperboard paperboard, paperboard, corrugated board and the like. is not.

The method for producing these high-strength composite papers will be described below. A material sheet of a prepreg laminate composed of fibers and a thermoplastic resin is heated to a temperature equal to or higher than the melting temperature of the thermoplastic resin, laminated on both sides of the paper 11, and then,
A high-strength composite paper is obtained by pressurizing and shaping with a press roller or the like and, if necessary, attaching a desired surface material to the surface thereof.

As a method of integrating the prepreg laminate and the paper by heat welding, the laminated prepregs are simultaneously heated to a melting temperature or higher, and if necessary, the paper to a melting temperature of the resin constituting the prepreg or less, and then to the prepreg. The laminated bodies are superposed, and are pressed at a pressure of 3 kg / cm ² or less in a press heated at room temperature to 80 ° C. to be cooled and integrated to form a laminated body.

At this time, it is necessary to deaerate the air present in the reinforcing layer. Usually, the air is heated to a temperature above the melting point of the resin forming the reinforcing layer and pressurized at a pressure of 3 kg / cm ² or less to deaerate. . If the pressure is within this range, the paper will not be crushed, so this deaeration can be performed in the step of integrating with the paper. As a matter of course, it is possible to use a laminated plate which is deaerated in advance and cooled.

The heating of the reinforcing layer and the paper may be performed without heating the prepreg and the paper (FIG. 430), or by heating the reinforcing layer and the paper in contact with each other ( Figure 440) is also possible.

At this time, when the high-temperature reinforcing layer comes into contact with the surface of the paper, the melted resin flows to the uneven portion of the surface of the paper, the melt is cooled and solidified, and the uneven portion is firmly fixed. It cuts in and the paper and the reinforcing layer are integrally joined.

The thermoplastic resin heated at the melting temperature or higher is generally in a state where it can be melted and flowed, but the weight ratio is 40.
% Composite fibers, the resin is held in the lattice of fibers in a state in which it cannot flow freely, so that when pressure for shaping is applied in that state, the fibers are skeletonized. Since the overall shape is determined as a stable shape, a highly accurate molded product can be obtained.

Since the reinforcing layer and the paper must be integrated while the reinforcing layer is in a molten state, it is necessary to devise a device so that the step of heating is changed to the step of integrating in a short time. is necessary. As an example of such a device, as shown in FIG. 4, a press 40 that integrates a reinforcing layer and paper is used.
It is recommended to combine this press with a preheating device 30 for the reinforcing layer provided with a moving means for moving the material rapidly. Paper burns at high temperatures, so 50 ° C
To 200 ° C., more preferably 100 ° C. to 200 ° C., for heating and molding.

The high-strength composite paper thus obtained is
It can be used for cardboard liners, dividers, wallpaper, etc. Further, the present invention will be described in detail with reference to specific examples.

[0033]

EXAMPLE The prepreg used in this example is of Japanese Patent Publication No.
It was manufactured by the method disclosed in JP-A-2-042168. In the case of glass fiber, the surface of a monofilament with a thickness of 13μ is treated with γ-methacryloxy-propyltrimethoxysilane, and about 1800 filaments are bundled into a twist-free yarn, and the yarn is pulled in one direction while pulling it with uniform tension. The resin was entangled with the yarn, and the yarn was impregnated with the resin while the resin was ironed with a hot roll to produce a prepreg. In the case of carbon fiber, without using a sizing agent, 12,000 tow collected monofilaments with a thickness of 7μ are aligned in one direction while pulling with a uniform tension, the resin is entangled with the yarn, and the resin is heated on a heat roll. The prepreg was manufactured by impregnating the yarn while squeezing. The prepreg manufactured in this manner has excellent adhesion between the fiber and the thermoplastic resin, and the fiber content can be changed as required to 30 to 90% by weight, and the thickness is 0.01 to 1.0 mm.
The fiber content is 40-80.
It is preferably used at a weight percentage of 0.01-0.6 mm. When the weight content of the fibers is 40% or less, the amount of the fibers is small and the strength is low, and when it is 80% or more, the amount of the resin is small and the adhesion between the fibers and the resin is lowered, and the strength is lowered, which is not preferable. Table 1 shows the constitution of prepregs manufactured for use in Examples and Comparative Examples of the present invention. Table 2 shows the properties of the paper used in the present invention.

[Example 1] Paper N is 400 mm in the longitudinal direction.
A rectangular piece having a length of 300 mm in the width direction was prepared. In addition, the prepreg A has a length of 400 in the fiber direction.
mm, one piece is cut into a length of 300 mm in the direction perpendicular to the fiber, similarly, a length of 300 mm is cut in the direction of the fiber and one piece is cut into a length of 400 mm in the direction perpendicular to the fiber, and the fiber directions of the two prepregs are orthogonal to each other. Thus, a two-layer laminated body was formed by stacking two sheets on top and bottom. The press type laminated body preheating device 30 shown in FIG. 4 is heated to 200 ° C., the prepreg laminated bodies 12 and 13 are sandwiched between the release films 22, and the resulting mixture is put into the preheating device to be 0.1 k.
Preheat at a pressure of g / cm ² for 2 minutes. After the preheating is completed, the pressure of the press type laminated plate preheating device 30 is released. Integrated device 40 in which the upper release film 22 is peeled off and heated to 70 ° C.
Then, the prepreg laminates 12 and 13 were superposed on both sides of the paper so that the surfaces of the prepreg laminates 12 and 13 without the release film were aligned. This time,
The prepreg laminates were laminated so that the surface having a fiber direction length of 400 mm was the surface. Next, the integrated device was tightened and pressurized with a pressure of 0.1 kg / cm ² for 1 minute, and then the high-strength composite paper was taken out. The high-strength composite paper was weighed and converted into a weight per 1 m ² . Further, the specific compressive strength of this high-strength composite paper was measured by the method specified in JIS P3902. Since the test body for compressive strength measurement is a laminated body in which the reinforcing layers are 0 degree and 90 degree, the longitudinal direction of the paper was cut out so as to match the longitudinal direction of the test body. The results are summarized in Table 3.

Example 2 A high-strength composite paper was molded in the same manner as in Example 1 except that prepreg B was used, and the physical properties were evaluated in the same manner as in Example 1. The results are summarized in Table 3.

[Example 3] A high-strength composite paper was molded in the same manner as in Example 1 except that prepreg C was used, and the physical properties were evaluated in the same manner as in Example 1. The results are summarized in Table 3.

[Example 4] A high-strength composite paper was molded in the same manner as in Example 1 except that prepreg D was used, and the physical properties were evaluated in the same manner as in Example 1. The results are summarized in Table 3.

[Example 5] A high-strength composite paper was molded in the same manner as in Example 1 except that prepreg E was used, and the physical properties were evaluated in the same manner as in Example 1. The results are summarized in Table 3.

Example 6 A high-strength composite paper was molded in the same manner as in Example 2 except that the paper O was used, and the physical properties were evaluated in the same manner as in Example 1. The results are summarized in Table 3. [Example 7] A high-strength composite paper was molded in the same manner as in Example 1 except that 0-degree prepreg A was used in place of the 0-degree and 90-degree two-layer laminate of the prepreg A. Physical properties were evaluated in the same manner as in Example 1. However, the test piece for measuring the specific compressive strength was cut out from the 0 degree direction and the 90 degree direction of the prepreg and tested. The results are shown in Table 3.

Example 8 High strength was obtained in the same manner as in Example 1 except that 0 degree prepreg A was used instead of the 0 degree and 90 degree two-layer laminate of prepreg A and O was used as the paper. Composite paper was molded. Physical properties were evaluated in the same manner as in Example 1. However, the test piece for measuring the specific compressive strength was cut out from the 0 degree direction and the 90 degree direction of the prepreg and tested. The results are shown in Table 3.

Example 9 A high-strength composite paper was produced in the same manner as in Example 1. However, after the prepreg laminate 12 from which the upper release film 22 has been peeled off is placed on the paper 11 with the release film 22 facing upward, the release film 22 is peeled off,
A non-woven fabric made of polyethylene terephthalate having a weight of 30 g per 1 m ² was placed on the prepreg laminate 12 as a surface material, and then the integrated device was tightened to 0.1 kg / cm ²
After pressurizing with the pressure of 1 minute for 1 minute, the high-strength composite paper was taken out. Next, apply an adhesive to the surface to which the non-woven fabric is attached,
A surface material for decoration, which was a thin plate having a wall nut thickness of 0.2 mm, was bonded with a slicer. By this method, a composite plate having a beautiful appearance was obtained. Physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 1 A high strength composite paper was molded in the same manner as in Example 1 except that prepreg F was used. However, the flow of resin disturbs the fibers and warps the composite paper,
It was not possible to cut out a test body for measuring the specific compressive strength. The weight was measured by cutting out a flat part. The results are summarized in Table 3.

Comparative Example 2 A high-strength composite paper was molded in the same manner as in Example 1 except that prepreg G was used, and the physical properties were evaluated in the same manner as in Example 1. Since the adhesion between the paper and the reinforcing layer was poor, a test sample for measuring the specific compressive strength could not be obtained. The weight was measured by the same method as in Example 1. The results are summarized in Table 3.

[Comparative Example 3] Physical properties of the paper N alone were evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 4 The physical properties of paper O alone were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

High-strength composite sheet according to the present invention is, above having a high compression strength, its both sides in the stiffness and tensile strength is very rather large, the reinforcing layer coefficient of thermal expansion is made of not lower fiber-reinforced synthetic resin formed The overall rigidity is extremely high,
It does not warp and can be constructed to be a very solid structure when used. Further, the end face coating makes the material highly durable.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a high-strength composite paper according to the present invention.

FIG. 2 is a schematic view showing a structure of high-strength composite paper in which a surface material is attached to one surface of a reinforcing layer.

FIG. 3 is a schematic view showing an embodiment of a high-strength composite paper having a processed end portion according to the present invention.

FIG. 4 is a schematic view showing a method for producing a high-strength composite paper by integrating a paper and a prepreg laminate of a reinforcing layer.

[Explanation of symbols] 1 High strength composite paper 10 High-strength composite paper with surface material 11 paper 12 Reinforcement material 13 Reinforcement material 14 Surface material 16 High-strength composite paper with edges processed 17 High-strength composite paper with processed edges 22 Release film 30 Press-type reinforcement preheating device 40 Integrated device

Continuation of the front page (56) Reference JP-A 61-229511 (JP, A) JP-A 49-99778 (JP, A) JP-A 50-160508 (JP, A) JP-A 1-163062 (JP , A) JP-A 2-160511 (JP, A) JP-A 63-74606 (JP, A) JP-A 58-31716 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) (Name) B32B 1/00-35/00 B29B 11/16 B29B 15/08-15/14 C08J 5/04-5/10 C08J 5/24

Claims (8)

(57) [Claims] 1. Obtained by impregnating one side surface or both front and back sides of a paper with reinforcing fibers aligned by aligning in one direction while pulling with uniform tension to a molten thermoplastic resin and impregnating the resin. Reinforcing layer which is a prepreg and contains reinforcing fibers in a weight content range of 40% or more and 80% or less, and a single or a plurality of prepregs having a coefficient of thermal expansion in the fiber direction of 10 ^-5 / ° C or less. A high-strength composite paper characterized by being laminated. 2. The high-strength composite paper according to claim 1, wherein the thermoplastic resin forming the reinforcing layer is a polypropylene resin, a polyethylene resin or a polystyrene resin. 3. The high-strength composite paper according to claim 1, wherein the fibers contained in the reinforcing layer are glass fibers. 4. The high-strength composite paper according to claim 1, wherein the prepreg containing the unidirectional fiber used as the reinforcing layer has a thickness of 1 mm or less. 5. The high-strength composite paper according to claim 1, wherein the reinforcing layer on the front surface side has a surface material on the surface thereof. 6. The high-strength composite paper according to claim 5, wherein the surface material is a non-woven fabric. 7. The end surface is coated with a surface material.
High-strength composite paper described in. 8. A prepreg obtained by impregnating a reinforcing fiber aligned in one direction while being pulled by a uniform tension with a molten thermoplastic resin to impregnate the resin, the reinforcing fiber comprising: A reinforcing layer in which a prepreg having a weight content of 40% or more and 80% or less and having a coefficient of thermal expansion in the fiber direction of 10 ^-5 / ° C or less is singly or laminated,
Heated above the melting temperature of the thermoplastic resin, overlaid on both sides of the paper, then press, roller or the like 0.0
A method for producing a high-strength composite paper, which comprises pressurizing and shaping at 1 kg / cm ² or more and 3 kg / cm ² or less, and further adhering a desired surface material to the surface thereof, if necessary.