JP2001328224A - Laminated sheet and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated sheet using a polypropylene resin foamed sheet, excellent in lightweight properties, bending rigidity, compression rigidity, thermal shaping properties and dimensional stability and capable of being made thin-walled and increased in an expansion ratio, and a method for manufacturing the same. SOLUTION: A reinforcing sheet is superposed on one surface of a foamable sheet consisting of a polypropylene resin having a long chain branch and a foaming agent to form a laminated sheet, and this laminated sheet is heated and foamed to integrally laminate the reinforcing sheet on one surface of the foamed sheet comprising the polypropylene resin having the long chain branch. The aspect ratio DZ/DXY of cells of the foamed sheet is 1.2 or more and the expansion ratio of the foamed sheet is 5-50 cm3/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated sheet of a polypropylene-based resin foam having a long chain branch which is excellent in light weight, flexural rigidity, compressive rigidity, thermoformability and dimensional stability, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, foams made of a thermoplastic resin have been used for various heat insulating materials, cushioning materials, flotation materials, etc. because of their excellent light weight, heat insulating properties and flexibility. Among them, in particular, polypropylene resin foam is widely used for interior parts such as vehicle doors, ceilings, instrument panels, etc. by secondary thermoforming because it is excellent in heat resistance and dimensional stability etc. Have been.

Conventionally, vehicle interior materials have been attached after attaching peripheral members such as a roof silencer to a vehicle. However, in recent years, modularization in vehicle assembly work has progressed, and peripheral members have been previously attached to vehicle interior materials. The mounting method of mounting the vehicle interior material with the peripheral members attached to the vehicle has been widely adopted, and the vehicle interior material is required to have higher bending rigidity and compression rigidity than ever. I have. In particular, ceiling materials are also required to be thin and lightweight.

Japanese Patent Application Laid-Open No. 11-291425 discloses that a sheet capable of suppressing foaming is laminated on a foamable sheet comprising a foaming agent and a modified resin obtained by reacting a polyolefin resin with a modifying monomer. There has been proposed a composite foam suitable for an interior material for a vehicle having a polyolefin-based resin foam having a spindle-shaped cell shape by foaming by heating.

[0005] However, in order to improve the expansion ratio of the thermoplastic resin foam for the purpose of improving the lightness of the composite foam, it is necessary to add a modifying monomer. Although a desired elongational stress can be applied to the thermoplastic resin, it is difficult to reduce the thickness of the raw sheet of the foam at the time of extrusion because the extensibility of the resin is reduced. It was impossible to produce a laminated sheet using the body.

[0006] In addition, there is a problem that odor and smoke are generated during the production and the working environment is inferior, and that the obtained foam is colored due to the modifying monomer.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention focuses on the high melt tension (elongational viscosity) of a polypropylene resin having a long chain branch, and is excellent in light weight using the same. In addition, the present invention provides a laminated sheet which is excellent in bending rigidity, compressive rigidity, thermoformability and dimensional stability, and can be made thin and has a high expansion ratio, and a method for producing the same.

[0008]

According to the first aspect of the present invention, there is provided a laminated sheet in which a reinforcing sheet is laminated and integrated on at least one surface of a foamed sheet made of a polypropylene resin having a long chain branch. is the aspect ratio D _Z / D _XY of the bubbles is 1.2 or more, and the expansion ratio laminated sheet, which is a 5 to 50 cm ³ / g is provided.

According to a second aspect of the present invention, there is provided the laminated sheet according to the first aspect, wherein a surface layer made of a thermoplastic resin is laminated and integrated on the surface of the reinforcing sheet.

According to a third aspect of the present invention, there is provided the laminated sheet according to the first or second aspect, wherein the reinforcing sheet is formed of glass fiber or carbon fiber.

According to the fourth aspect of the present invention, a foamable laminated sheet is formed by laminating a reinforcing sheet on at least one surface of a foamable sheet comprising a polypropylene resin having a long chain branch and a foaming agent. Is heated and foamed, and the method for producing a laminated sheet according to any one of claims 1 to 3 is provided.

The polypropylene resin having a long chain branch used in the present invention has a higher melt tension (elongational viscosity) than a conventional polypropylene resin, and foams using this resin are also known. ing. As a method for producing a polypropylene resin having this long chain branch, for example,
As disclosed in JP-A-2-69533,
A method in which a linear homopolypropylene is treated with ionizing radiation in an inert gas atmosphere and then subjected to high-temperature aging to produce the same. Through this series of operations, the free radicals generated in the molecular chain of the polypropylene are recombined in a reaction-controlled state, and a long-chain branch is formed in the main chain of the polypropylene. The polypropylene resin having a long chain branch produced in this manner is sold, for example, by Montel SDC Sunrise Co., Ltd. under the trade name: HMS.
HMS is a homopolymer of propylene.

In the present invention, the polypropylene resin having a long-chain branch preferably has a melt index (MI) of 0.05 to 20 as measured according to JIS K6758. If the MI is less than 0.05, the viscosity is too high to obtain a foam of high magnification, and the load on the extruder increases, making extrusion difficult. This is because the resin has a low viscosity with respect to the elongation of the resin at the time of foaming, and easily breaks, so that a foam having a high magnification cannot be obtained.

The long-chain branching of the resin mainly has a great effect on the viscoelasticity of the flow region. Therefore, the presence or absence of significant long-chain branching is determined, for example, by the fact that the melt-elongational viscosity of a polypropylene-based resin having long-chain branching and a polypropylene having no long-chain branching corresponding to substantially the same weight average molecular weight. It can be confirmed by the ratio with the melt extensional viscosity of the system resin. The melt extensional viscosity of the resin can be easily measured using a commercially available melt extensional viscometer (for example, a melten rheometer manufactured by Toyo Seiki Co., Ltd.).

The polypropylene resin having a long chain branch used in the present invention has an elongation strain rate of 0.01 to 1.0 (s).
^-1 ) The melt elongation viscosity η _A (Pa ·
s), the maximum value of the ratio of η _B (Pa · s) is η _B / η _A = 3
-100, B / A = 10, and A = 0.1-1.0.

[0016] The reason is that it is less than η _B / η _A 3.0, viscosity tends to foam breaking low to elongation of the resin upon foaming is not a high magnification of the foam is obtained, conversely, eta _B / Η _A
This is because it is difficult to obtain a polypropylene resin having a value of more than 100. Incidentally, η _B / η _A of a conventional polypropylene resin having no long-chain branch is generally 2 or less.

The polypropylene resin having a long chain branch used in the present invention includes a propylene homopolymer and a propylene resin containing 85% by weight or more of propylene.
α-olefin copolymers or mixtures thereof. Here, as the α-olefin, ethylene, 1-
Hexene, 4-methyl-1-pentene, 1-octene,
Examples thereof include 1-butene and 1-pentene.

A general-purpose thermoplastic resin may be added to the polypropylene resin having a long-chain branch, if necessary, in order to adjust the fluidity, expansion ratio, aspect ratio and the like of the resin. Thus, when a laminated sheet is manufactured using the method for manufacturing a laminated sheet described later, it is possible to easily and reliably adjust the aspect ratio D _Z / D _XY of the bubbles of the foamed sheet to be within a predetermined range. Can, so,
A laminated sheet having excellent bending rigidity can be reliably manufactured.

Moreover, since the resin thus obtained has excellent fluidity, the resulting laminated sheet has excellent moldability and also has excellent elongation stress and fluidity during foaming. The foamed sheet can be foamed at normal pressure, the resulting foamed sheet has excellent thickness accuracy, and the resulting laminated sheet also has excellent thickness accuracy, and therefore, the molded product obtained by molding the laminated sheet is also complicated. It can be shaped and has excellent surface properties.

The above-mentioned general-purpose thermoplastic resin is not particularly limited as long as it has been conventionally used for foams, and examples thereof include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Polyethylene, isotactic polypropylene, polypropylene such as syndiotactic polypropylene, polybutene, polyolefin resins such as ethylene-α-olefin copolymer, ethylene-propylene-diene terpolymer, ethylene-vinyl acetate Copolymer, ethylene-
Acrylic ester copolymers, polystyrene, polystyrene-based resins such as polystyrene-based thermoplastic resin elastomers, etc., among which polyolefin-based resins are excellent in all of light weight, chemical resistance, flexibility and high elasticity Resins are preferable, and general-purpose polypropylene is more preferable from the viewpoint of compatibility with a polypropylene resin having a long-chain branch. In addition, the said thermoplastic resin may be used independently or may be used together.

The α-olefin includes propylene, 1-butene, 1-pentene, 1-hexene, 4-
Examples thereof include methyl-1-pentene, 1-heptene, and 1-octene. The copolymer containing an ethylene component may be any of a block copolymer and a random copolymer.

The amount of the thermoplastic resin is 200 parts by weight or less, preferably 150 parts by weight or less, based on 100 parts by weight of the polypropylene resin having a long chain branch.
More preferably, it is 100 parts by weight or less. The reason is that if the amount exceeds 200 parts by weight, foaming is significantly inhibited, and it becomes difficult to obtain a high-magnification foam.

The polypropylene resin having a long chain branch may contain a cell nucleating agent, a flame retardant, a filler,
Additives such as antioxidants and pigments may be blended.

[0024] Such additives are widely known. For example, examples of the foam nucleating agent include calcium carbonate, talc, magnesium oxide, zinc oxide, silicon dioxide, titanium oxide, citric acid, sodium bicarbonate, orthoboric acid and talc, and alkali metal salts of fatty acids.

Examples of the flame retardant include brominated flame retardants such as hexabromobiphenol ether and decabromodiphenyl ether; phosphorus-containing flame retardants such as ammonium polyphosphate, trimethyl phosphate and triethyl phosphate;
There are melamine derivatives, inorganic flame retardants and the like.

Most of the cells of the foamed sheet made of the polypropylene resin having long chain branches are formed in a spindle shape in which the length direction is oriented in the thickness direction of the foamed sheet. By orienting in this way, the foamed sheet is formed to have excellent compression rigidity in the thickness direction.

The aspect ratio D _Z of the cells of the above foamed sheet
When the / D _XY is small, the compression stiffness in the thickness direction of the obtained foamed sheet is reduced.
5 or more is preferable, and 2 or more is more preferable.

Note that the aspect ratio D _Z / D _XY of the cells of the foam sheet is measured in the following manner.
That is, first, the foamed sheet is cut in the thickness direction, and an electron micrograph (for example, about 40 times) of the cut surface is taken. The cut surface of the bubbles are exposed on the cut surface, singled out 50 bubbles throughout the thickness direction, and cut in perpendicular to the maximum thickness direction length D _Z and the thickness direction of the foamed sheet of the foamed sheet The maximum length D _XY in the direction along the plane is measured, and the aspect ratio (D _Z / D _XY ) of each bubble is calculated. Then, the aspect ratio (D _Z / D) of each of the obtained bubbles is obtained.
The average value of _XY ) is calculated, and is set as the aspect ratio D _Z / D _XY of the cells of the foam sheet.

If the foaming ratio of the foamed sheet is too large, the mechanical strength such as compression stiffness and bending stiffness of the obtained laminated sheet is reduced, and if it is too small, the lightweight property of the obtained laminated sheet is reduced. limited to ^{5~50cm 3 / g, 10~30cm 3 /} g are preferred. The expansion ratio of the foamed sheet is the reciprocal of the apparent density measured according to JIS K6767.

When the thickness of the foamed sheet is the same, there is an opposing relationship between the expansion ratio and the bending strength.
If it exceeds 0 cm ³ / g, it tends to be difficult to obtain the necessary bending stress described later when formed into a laminated sheet. Therefore, the expansion ratio of the foam sheet is 50 cm.
³ / g or less.

The laminated sheet of the present invention is formed by laminating and integrating a reinforcing sheet on one side of the above foam sheet, preferably on both sides. Examples of the reinforcing sheet include a dry thermal bonding method, a needle punching method and a wet type. Thermal nonwoven fabrics made of inorganic fibers such as glass fibers and carbon fibers by a papermaking method performed in, a thermal cloth mat woven by roving, a glass cloth made by weaving glass fibers or carbon fibers, and the like. A thermal face mat which is a nonwoven fabric made of glass fiber or carbon fiber by a wet papermaking method is preferable.
When the reinforcing sheets are laminated and integrated on both sides of the foamed sheet, these reinforcing sheets may be of different types, but are of the same type from the viewpoint of dimensional stability of the obtained laminated sheet. It is preferable to use

When the inorganic fibers constituting the thermal face mat are glass fibers, the diameter of the glass fibers is 8
To 25 μm, and the length of the glass fiber is preferably 30 mm or less. When the inorganic fibers constituting the thermal face mat are carbon fibers, the diameter of the carbon fibers is 4
To 15 μm, and the carbon fiber preferably has a length of 30 mm or less. Further, the thermal face mat preferably has a thickness of 10 μm to 1 mm and a weight of 10 to 50 g / m ² .

The thermal face mat contains a binder for binding the inorganic fibers to each other. Examples of such a binder include polyvinyl alcohol-based resins, saturated polyester-based resins, unsaturated polyester-based resins, and the like. Acrylic resins such as polymethyl (meth) acrylate, polybutyl (meth) acrylate, poly-n-tetradecyl (meth) acrylate, poly-n-propyl (meth) acrylate, polyisobutyl (meth) acrylate, and linear urethane resins Urethane resin,
A thermoplastic resin such as an epoxy resin and a vinyl acetate resin is exemplified.

If the glass transition temperature Tg of the thermoplastic resin used as the binder is high, the moldability of the obtained laminated sheet may be reduced, and if the glass transition temperature Tg is low, the strength of the obtained thermal face mat may be reduced. Because there is
0-40 ° C is preferred.

The tensile strength of the reinforcing sheet is preferably 30 kPa or more for the following reasons. That is,
As described below, the laminated sheet is manufactured by foaming a foamed laminated sheet obtained by laminating and integrating a reinforcing sheet on one or both sides of a foamable resin sheet made of a polypropylene resin having a long chain branch. The foaming in the plane direction is regulated by the reinforcing sheet, while the foaming in the thickness direction is in a free foaming state, and the foaming direction is directed in the thickness direction of the foamable resin sheet, and the bubbles of the obtained foamed sheet are removed. Formed in a spindle shape with its length direction oriented in the thickness direction of the foam sheet, that is, its aspect ratio D
It is formed so that _Z / _DXY falls within a predetermined range described later.

Therefore, when the tensile strength of the reinforcing sheet is small, the foaming of the foamable resin sheet in the surface direction cannot be effectively regulated by the reinforcing sheet, and the aspect ratio of the cells of the obtained foamed sheet cannot be effectively controlled. Ratio D _Z / D
_XY does not fall within the predetermined range, and it may not be possible to impart desired bending rigidity to the obtained laminated sheet,
The reinforcing sheet cannot withstand the inflation pressure of the foam sheet, and may be torn.

Further, when the linear expansion coefficient of the reinforcing sheet is large, the linear expansion coefficient of the obtained laminated sheet also becomes large, and the expansion and contraction of the laminated sheet due to a temperature change becomes large, and the dimensional stability is lowered, Sometimes it hangs down due to its own weight, so 5 × 10 ^-5 /
C. or lower, more preferably 1 × 10 ⁻⁵ / ° C. or lower.

Further, a surface layer made of a thermoplastic resin may be laminated and integrated on the surface of the reinforcing sheet. By further laminating and integrating the surface layer on the surface of the reinforcing sheet, the reinforcing sheet can be made of inorganic fibers. When it is formed from, it functions as a binder for binding the inorganic fibers to each other, and can reduce the coefficient of linear expansion of the reinforcing sheet, and thus, the resulting laminated sheet has excellent dimensional stability. It can be. When the reinforcing sheet is laminated and integrated on both sides of the foam sheet, the surface layer may be laminated and integrated only on the surface of one of the reinforcing sheets.

Examples of the surface layer include films made of thermoplastic resins such as polystyrene, polyethylene, polypropylene, polybutene, nylon, and polyethylene terephthalate.

When a film made of a thermoplastic resin is used as the surface layer and a sheet made of inorganic fibers is used as the reinforcing sheet, the thermoplastic resin constituting the surface layer is made of the reinforcing sheet. Since it also serves as an adhesive between the reinforcing sheet and the foamed sheet by entering between the inorganic fibers constituting the foamed sheet, the thermoplastic resin constituting the surface layer is a thermoplastic resin constituting the foamed sheet. Those having compatibility are preferred.

On the other hand, if the thickness of the surface layer is too large, the lightness of the resulting laminated sheet may be reduced. If the thickness is small, the effect of laminating and integrating the surface layer on the reinforcing sheet may not be exhibited. Therefore, 10 to 200 μm is preferable.

If the maximum bending stress of the laminated sheet of the present invention is low, the bending strength of the foamed sheet is reduced.
It is preferably at least MPa, and more preferably at least 4 MPa.

Next, a method of manufacturing the laminated sheet will be described. As a method of manufacturing the laminated sheet, for example, a reinforcing sheet is laminated and integrated on one or both sides of a foamable resin sheet made of a polypropylene resin having a long chain branch and a foaming agent, and further, if necessary, the reinforcing sheet A method for producing the laminated sheet by laminating and integrating the thermoplastic resin film constituting the surface layer thereon to form a foamable laminated sheet, and foaming the foamable laminated sheet, polypropylene having a long chain branch. A reinforcing sheet is superimposed on one or both surfaces of a foamable resin sheet composed of a base resin and a foaming agent, and if necessary, the thermoplastic resin film constituting a surface layer is superimposed on the reinforcing sheet to form a foamable laminate. A sheet is formed, and the foamed laminated sheet is foamed, and at the same time, the foamed resin sheet is foamed. Sheets, if necessary, and a method of producing the laminated sheet and the like by a thermoplastic resin film may be integrated.

The foaming agent is not particularly limited as long as it is widely used in the production of foams. Inorganic pyrolysis such as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and azide compounds is not limited. Foaming agent, azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, toluenesulfonylhydrazide, 4,4
-Oxybis (benzenesulfonylhydrazide), barium azodicarboxylate, trihydrazinotriazine, p
Organic pyrolysis-type foaming agents such as toluenesulfonyl semicarbazide.

If the amount of the foaming agent is too large, the foam may be broken, and if the amount is small, the foam may not be foamed. Mixed resin of thermoplastic resin 1
1 to 50 parts by weight is preferable with respect to 00 parts by weight.

The method for producing the foamable resin sheet includes, for example, a polypropylene resin having a long chain branch,
Then, the thermoplastic resin to be blended as required is supplied to an extruder, melted and kneaded, and the foaming agent is uniformly dispersed in the resin by adding the foaming agent to the resin in the molten state. Extruded into a foamed resin sheet.

As a method for laminating and integrating a reinforcing sheet on one surface of the foamable resin sheet, for example, a method for laminating and integrating the reinforcing sheet on one surface of the foamable resin sheet while heating, A method in which a reinforcing sheet is pressed onto one surface of a foamed resin sheet and laminated and integrated, that is, a foamable resin sheet is extruded from a T-die attached to the tip of an extruder, and the surface immediately after the extrusion is melted. After placing the reinforcing sheet on one side of the foamable resin sheet in a state, the sheet is supplied between a pair of cooling rolls, and the foamable resin sheet is sandwiched and integrated by these cooling rolls, thereby forming one side of the foamable resin sheet. A method of laminating and integrating a reinforcing sheet, a method of laminating and integrating a foamable resin sheet and a reinforcing sheet via an adhesive, and the like. The above method is preferred since it is possible to finely adjust.

When a surface layer is further laminated and integrated on the surface of the reinforcing sheet, for example, a reinforcing sheet and a thermoplastic resin film are formed on one surface of the foamable resin sheet so that the reinforcing sheet is on the inside. After laminating, a method in which the thermoplastic resin film is heated to a temperature equal to or higher than the softening temperature and the surface layer made of the reinforcing sheet and the thermoplastic resin film is laminated and integrated on one surface of the foamable resin sheet.

As a method for heating the foamable laminated sheet manufactured as described above, a general-purpose heating apparatus conventionally used for manufacturing a foam is used. For example, a pair of heating apparatuses arranged in a facing state is used. A roll-type heating device or a belt-type heating device for supplying a foamable laminated sheet between heating rolls or heating belts to heat the foamable laminated sheet, a hot-air constant temperature bath for blowing hot air to the foamable laminated sheet, and a foamable laminated sheet Bath, metal bath, salt bath and the like. If the foaming temperature is too low, the elongational viscosity is too low to cause outgassing, and a desired foaming ratio may not be obtained. If the foaming time is too short, a sufficient foaming ratio cannot be obtained.If the foaming time is too long, not only the foaming ratio decreases due to outgassing, but also the coarsening of the bubbles and the decrease in the aspect ratio occur, and the strength decreases. There is a possibility that. Therefore, although the foaming time greatly varies depending on the foaming method, it is desirable to cool the foam immediately after the maximum foaming ratio is obtained.

When the foamable resin sheet of the foamable laminated sheet is foamed in the above manner, the foaming of the foamable resin sheet is performed because the reinforcing sheet is laminated and integrated on one surface of the foamable resin sheet. While the foaming in the direction is regulated by the reinforcing sheet, the foaming in the thickness direction is in a free foaming state without being regulated by the reinforcing sheet.

However, the foaming direction of the foamable resin sheet is regulated so as to be oriented in the thickness direction.
The cells of the foamed sheet obtained by foaming the foamable resin sheet are formed into a spindle shape having its length direction oriented in the thickness direction of the foamable resin sheet and having an aspect ratio D _Z / D _XY within a predetermined range. Is done.

Therefore, the obtained laminated sheet is partially formed of a foamed sheet, and has excellent compression rigidity and bending rigidity while maintaining lightness.

Further, since the laminated sheet is formed by laminating and integrating a reinforcing sheet on one surface of a foamed sheet excellent in formability, a hot press method of performing heat molding with a general compression molding machine, and a method of forming a foamed sheet. After heating to the softening point or higher, the foamed sheet can be formed into a desired shape by a general-purpose molding method such as a cold press method or a vacuum molding method in which shape transfer is performed in a mold maintained at a temperature lower than the softening point.

[0054]

The laminated sheet of the present invention uses a polypropylene resin having a long chain branch, which exhibits a higher melt tension (elongational viscosity) than a conventional polypropylene resin, as the foamed sheet. A reinforcing sheet is laminated and integrated on one side, and the above-mentioned foamed sheet is oriented with its length direction in the thickness direction of the laminated sheet.
Since it has air bubbles having the above aspect ratio D _Z / D _XY and has a bending strength of 2.0 MPa or more, it has excellent compression rigidity, bending rigidity, and compression rigidity in the thickness direction.

In particular, in the foamed sheet of the laminated sheet, since the bubbles are oriented in the length direction in the thickness direction of the laminated sheet and have an aspect ratio D _Z / D _XY within a predetermined range, the foaming ratio is increased. Even in such cases, it has excellent bending rigidity.

Therefore, since the laminated sheet of the present invention uses a polypropylene resin having a long-chain branch in the foamable resin sheet, the foamed sheet having a high expansion ratio as the foamed sheet is not crosslinked. It can be used, and is formed to be easily recyclable with excellent bending rigidity and compressive rigidity while maintaining high lightness.

The laminated sheet of the present invention has excellent dimensional stability with almost no dimensional change due to temperature change because the reinforcing sheet is laminated and integrated on one surface of the foamed sheet.

Further, when a surface layer made of a thermoplastic resin is laminated and integrated on the surface of the reinforcing sheet of the laminated sheet, the surface layer is used for reinforcing the reinforcing sheet. In order to play a role, the obtained laminated sheet has more excellent mechanical rigidity such as bending rigidity and compressive rigidity.

In addition, when the reinforcing sheet of the laminated sheet is made of glass fiber or carbon fiber as described in claim 3, the reinforcing sheet has excellent moldability, and thus is obtained. The laminated sheet has excellent moldability. Moreover, when a surface layer made of a thermoplastic resin is laminated and integrated on the surface of the reinforcing sheet, this surface layer penetrates between the glass fibers or carbon fibers constituting the reinforcing sheet and serves as a binder to reinforce. Since the rigidity of the sheet is improved, the obtained laminated sheet has further excellent mechanical rigidity such as bending rigidity and compressive rigidity.

In producing the laminated sheet, a reinforcing sheet is laminated on one side of the foaming resin sheet to form a foaming laminated sheet, and then the foaming laminated sheet is heated and foamed. If the method of manufacturing a laminated sheet to be used is used, a foamable laminated sheet is manufactured by a simple operation of laminating a reinforcing sheet on one side of a foamable resin sheet, and then the foamable laminated sheet is foamed using a general-purpose heating means. By doing so, it is possible to easily and reliably manufacture a laminated sheet having excellent mechanical rigidity such as bending rigidity and compressive rigidity as described above, and excellent in light weight, dimensional stability and moldability.

[0061]

(Example 1) In order to produce an expandable polypropylene sheet, a co-rotating twin-screw extruder (trade name "TEX-4" manufactured by Nippon Steel Works Co., Ltd.) was used.
4 ", hereinafter referred to as" TEX-44 ").

The TEX-44 is a self wiping 2
With a L / D of 45.5 and D of 47
mm. The cylinder barrel is divided into a first barrel to a twelfth barrel from upstream to downstream of the extruder, and a coat hanger die having a width of 500 mm is attached to the tip of the twelfth barrel.

Further, a side feeder is provided in the sixth barrel for supplying the foaming agent, and a vacuum vent is provided in the eleventh barrel for recovering components volatilized in the cylinder barrel.

In the following operation, the temperature of the first barrel is set to 200 ° C., and the temperature of the second to sixth barrels is set to 22 ° C.
At 0 ° C., raise the temperature of barrels 7 through 12 to 180 ° C.
Temperature of the adapter and coat hanger die to 16 ° C.
The temperature was set at 5 ° C., and the screw rotation speed was set at 40 rpm.

From a hopper provided at the rear end of the first barrel of the TEX-44, a polypropylene resin “HMS PF-814” having a long chain branch (Montell SDK Sunrise, melt index (MI) = 3) .
0 g / min, density = 0.90 g / cm ³ ) and a general-purpose homopolypropylene resin “PB170A” (manufactured by Montell SDC Sunrise, MI = 0.35 g / 10)
And a density of 0.91 g / cm ³ )
Azodicarbonamide is supplied from a side feeder provided in the sixth barrel of EX-44, and a polypropylene-based resin having a long-chain branch and homopolypropylene and azodicarbonamide are melted and kneaded, and then TEX-4.
0.4 from the coat hanger die attached to the tip of No.4
mm foamable resin sheet was obtained. The amount of the polypropylene resin having a long chain branch was 6 kg / hour, the amount of the homopolypropylene was 4 kg / hour, and the amount of the azodicarbonamide was 0.24 kg / hour.

On the other hand, a continuous sheet of paper having a width of 500 mm
Spaper (Olivest product name "SUO-025"
C ", coefficient of linear expansion = 0.4 × 10^-Five/ ° C, weight = 25 g
/ M ^Two, Thickness = 0.22 mm, glass fiber diameter = 9 μm,
Glass fiber length = 25 mm, binder = polyvinyl alcohol
70% by weight coal and 30% by weight thermoplastic urethane resin
%) On one side, a width of 500 mm and a thickness of 80 μm
Homopolypropylene “SH-152” (manufactured by Tokuyama Corporation,
MI = 15 g / 10 min, density = 0.91 g / cm ^Three) Or
Layer by heat laminating
The laminated body material (reinforcement sheet) was obtained.

Then, on both sides of the foamable resin sheet,
The laminated face material was overlapped so that the glass paper was on the inside, heated to a temperature equal to or higher than the softening temperature of the constituent resin and equal to or lower than the foaming temperature, and thermocompression bonded to produce a foamable laminated sheet. The obtained foamable laminated sheet is cut into a square of 100 cm, and the foamable laminated sheet is stretched over a belt-type heating foaming apparatus (a preheating zone 1, a foaming zone 2, a cooling zone 3, and these three zones shown in FIG. 1). And a pair of conveyor belts 4 arranged at regular intervals in the up-down direction) and transported while heating to 220 ° C. in the foaming zone 2 via the preheating zone 1. The foamed laminated sheet is foamed in the foaming zone 2, and the foamed laminated sheet 5 being foamed is sandwiched and pressed from above and below between the opposing inner surfaces of the pair of conveyor belts 4, and cooled and cooled in the cooling zone 3. A 6 mm laminated sheet was obtained.

(Example 2) The same procedure as in Example 1 was carried out except that the amount of azodicarbonamide was 0.32 kg / hour and the thickness of the foamable resin sheet was 0.3 mm. A 6 mm laminated sheet was obtained.

Comparative Example 1 A homopolypropylene resin “PB” was prepared without adding a polypropylene resin having a long chain branch.
170A "was carried out in the same manner as in Example 1 except that the input amount was 10 kg / hour. However, the thickness of the foam was thin, and no sample worthy of evaluation was obtained.

(Comparative Example 2) The following apparatus was used to produce an expandable polypropylene sheet slightly crosslinked with p-quinonedioxime. That is, a co-rotating twin screw extruder (trade name “B
(T40), hereinafter referred to as "BT40"), using a manufacturing apparatus in which TEX-44 is connected via an adapter to the tip.

The BT 40 is provided with a self-wiping double-start screw having an L / D of 35 and a D (diameter) of 39 mm.
It is. The cylinder barrel is divided from the first barrel to the fourth barrel from the upstream to the downstream side of the extruder, and an adapter which can be continuously connected to a TEX-44 type co-rotating twin-screw extruder is provided at the tip of the fourth barrel. Provided.

In the BT40, in the following operation, the temperature of the first barrel was set to 180 ° C., the temperature of the second to fourth barrels was set to 220 ° C., and the screw rotation speed was set to 150 rpm.

Regarding TEX-44, in the following operation, the first barrel is constantly cooled and the second barrel to the fourth barrel are cooled.
Setting the temperature of the barrel to 150 ° C., the temperature of the fifth to eighth barrels to 170 ° C., the temperature of the ninth to twelfth barrels to 180 ° C., the temperature of the adapter and the coat hanger die to 160 ° C., Screw speed 40
rpm.

A random type polypropylene (manufactured by Nippon Polychem Co., Ltd., MI = 0.8 g / 10 min, density =
0.9 g / cm ³ ) and p-quinone dioxime (trade name “Barnock GM-P” manufactured by Ouchi Shinko Chemical Co., Ltd.) as a modifying additive are separately supplied, melted and kneaded to produce a modified polypropylene. At the same time, the resulting modified polypropylene was continuously supplied to TEX-44 via an adapter. Incidentally, the input amount of the above-mentioned polypropylene was 10 kg / hour, and the input amount of p-quinonedioxime was 0.0
8 kg / hour.

Further, a homopolypropylene “MA3” (manufactured by Nippon Polychem Co., Ltd., melt index = 10 g / 10) was supplied from a hopper provided at the rear end of the first barrel of TEX-44.
Min., Density = 0.91 g / cm ³ ), and azodicarbonamide was supplied from a side feeder provided in the sixth barrel of TEX-44.
Was melted and kneaded, and a foamable polypropylene sheet having a thickness of 0.4 mm was obtained from a coat hanger die attached to the tip of TEX-44. The amount of homopolypropylene was 10 kg /
At this time, the input amount of azodicarbonamide was 0.24 kg / hour. Lamination and foaming of the following glass paper were performed in the same manner as in Example 1 to obtain a laminated sheet having a thickness of 6 mm.

(Comparative Example 3) The same procedure as in Comparative Example 2 was carried out except that the amount of azodicarbonamide added was 0.32 kg / hour and the thickness of the expandable polypropylene sheet was set to 0.3 mm. However, a uniform sample having a thickness of 0.3 mm could not be obtained due to severe drilling and tearing of the raw material during extrusion.

Of the laminated sheets obtained in Example 1, Example 2, and Comparative Examples 1 to 3, samples having a desired thickness of 6.0 mm were obtained. And the aspect ratio D _Z / D _XY and the maximum bending stress and the coefficient of linear expansion of the laminated sheet were measured by the following methods. The results are shown in Table 1.

(Expansion ratio) Measured in accordance with JIS K6767.

(Maximum bending stress) A laminated sheet having a length of 150
mm and a width of 50 mm, and measured according to JIS K7221.

(Linear Expansion Coefficient) Length 150
A test piece having a size of 20 mm × width 20 mm × thickness 6.0 mm was cut out and left in an atmosphere of 85 ° C. for 24 hours.
The test piece is marked with a mark having a distance of 130 mm on the surface of the test piece. Then, place the test piece in an 80 ° C.
Measure the length ( _L80 mm) between the marked lines after standing for a period of time. Next, the test piece was left in a thermostat at 0 ° C. for 6 hours, and then the length (L ₀ mm) between the marked lines was measured, and the coefficient of linear expansion was calculated by the following equation. α = (L ₈₀ −L ₀ ) / (130 × 80 ° C.)

[0081]

[Table 1]

[0082]

Since the laminated sheet of the present invention has the above-mentioned structure, it is possible to obtain a foam having a high working ratio, a safe working environment, a thin foam, and a light weight, flexural rigidity, and the like. Since it has excellent compression rigidity, heat shaping properties and dimensional stability, it is suitably used for interior materials for automobiles, heat insulating materials, cushioning materials and the like.

According to the method for producing a laminated sheet of the present invention, a reinforcing sheet is laminated on one side of a foamable resin sheet to obtain a foamable laminated sheet. The above-mentioned laminated sheet can be reliably obtained by a simple process of using and foaming.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a heating device used in an example.

[Description of Signs] 1 Preheating zone 2 Foaming zone 3 Cooling zone 4 Conveyor belt 5 Laminated sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 9:00 B29C 67/22 F term (Reference) 4F100 AD11B AD11D AG00B AG00D AK01C AK01E AK07A AK07K AT00B AT00D BA02 BA03 BA05 BA06 BA07 BA10A BA10B BA10C BA10E CA01A DG01B DG01D DJ01A EC032 EG00 EJ022 EJ172 EJ422 EJ503 GB33 GB90 JA20A JB16C JB16E JJ02 JK01 JK01B JK01D JK04 JK05 JK11 JL03 JL02 AD02A02A02A03A03 UG07

Claims (4)

[Claims] 1. A laminated sheet in which a reinforcing sheet is laminated and integrated on at least one surface of a foamed sheet made of a polypropylene resin having a long chain branch, wherein the foamed sheet has an aspect ratio D _Z / D of cells. A laminated sheet having an _XY of 1.2 or more and an expansion ratio of 5 to 50 cm ³ / g. 2. The laminated sheet according to claim 1, wherein a surface layer made of a thermoplastic resin is laminated and integrated on the surface of the reinforcing sheet. 3. The laminated sheet according to claim 1, wherein the reinforcing sheet is formed from glass fiber or carbon fiber. 4. A foamable laminated sheet is formed by laminating a reinforcing sheet on at least one surface of a foamable sheet made of a polypropylene resin having a long chain branch and a foaming agent, and then heating and foaming the foamable laminated sheet. The method for producing a laminated sheet according to any one of claims 1 to 3, wherein: