JP2001191353A - Manufacturing method of foam composite sheet - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] A cell shape of a foam is a spindle shape oriented in a thickness direction, and therefore, exhibits excellent compressive strength, load resistance, bending strength, and the like, and has a smooth surface. A foam composite sheet having excellent properties can be obtained with high productivity. SOLUTION: When the foamable sheet 1 is heated on both sides of a foamable sheet 1 made of a thermoplastic resin composition containing a pyrolytic foaming agent, the foaming force in the in-plane direction of the sheet 1 is suppressed. In a state where the sheet-like surface material 2 having the obtained strength is laminated, the sheet-like surface material 2 is sandwiched between two upper and lower continuous endless belts 7,
At a temperature that is equal to or higher than the melting point of the thermoplastic resin and equal to or lower than the decomposition temperature of the pyrolytic foaming agent, the material is heated and fused under pressure, and then heated to foam the foamable sheet 1. Cool to a temperature below the melting point of the plastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a foamed composite sheet made of a thermoplastic resin.

[0002]

2. Description of the Related Art Conventionally, foams made of thermoplastic resins such as polyolefin resins have been widely used as various heat insulating materials, cushioning materials, flotation materials, etc. because of their excellent lightness, heat insulating properties, and flexibility. ing. However, except for foams made of hard resin, most of foams made of ordinary thermoplastic resin generally have a low compressive strength, and therefore, excellent compression properties such as roof insulation of buildings and core materials under floors are used. There is a problem that the use in fields and applications where strength and load resistance are required is limited.

[0003] In order to cope with such a problem, various studies have been made. For example, Japanese Patent Laid-Open No. 9-150431
Japanese Patent Application Laid-Open Publication No. H11-260, "A heat-expandable thermoplastic resin sheet containing a pyrolyzable foaming agent, at least one surface of the heat-expandable thermoplastic resin sheet when heated in the in-plane direction (longitudinal direction and width direction) of the sheet. Laminating a sheet-like material having a strength capable of suppressing foaming, a step of obtaining an integrated foamable sheet, and a step of foaming the foamable sheet by heating the foamable sheet to a decomposition temperature of a pyrolytic foaming agent or higher. The present invention discloses a method for producing a foam containing the same, and a foamable sheet in which the sheet-like material is made of an inorganic fiber and a binder binding the same.

The foam obtained by the manufacturing method disclosed in the above disclosure has a spindle shape having a major axis in the thickness direction of the sheet, and thus exhibits high strength in the thickness direction of the sheet.
Therefore, the compressive strength of the foam is increased, and the range of application in fields and applications where excellent compressive strength and load resistance are required is widened. In addition, since the spindle-shaped cells are arranged neatly in the thickness direction of the sheet, the mechanical properties of the foam have extremely strong anisotropy. For example, although the compression strength is high, the foam has good flexibility in the bending direction. And other unique characteristics. Therefore, the above-mentioned foam in which sheet-like materials are laminated on both sides can be suitably used as a roof insulation material, an automobile ceiling material and the like.

FIG. 3 is a schematic view showing the steps of the extrusion laminating method, and FIG. 4 is a schematic view showing a state where the foamable thermoplastic resin sheet is sandwiched between rolls.

As shown in FIG. 3, when the foamed thermoplastic resin sheet 14 immediately after being extruded from the extrusion die 13 is passed between two rolls 16 as shown in FIG. The sheet-like material 15 having a strength capable of suppressing foaming in the direction was sandwiched on one or both sides between the roll 16 and the foamable thermoplastic resin sheet 14 and laminated (extruded lamination method).

In the case of the above manufacturing method, the expandable thermoplastic resin sheet 14 and the sheet material 15 are
The layers are laminated and fused by pressing to exhibit lamination strength (adhesion strength).

However, the roll 16 also plays a role in equalizing the thickness distribution of the expandable thermoplastic resin sheet 14 formed into a sheet by the extrusion die 13, and the thickness unevenness (fine) generated minutely in the width direction. As shown in FIG. 4, the peaks and the valleys are equalized by a so-called bank 17 that is generated when the sheet is nipped by the roll 16.

When the foamable thermoplastic resin sheet 14 is used alone, the thickness distribution can be equalized as described above. However, when the foamable thermoplastic resin sheet 14 and the sheet-like material 15 are laminated and fused, the above-described thickness distribution can be obtained. When the distribution equalization and the lamination and fusion of the sheet-like material 15 are simultaneously performed, the sheet-like material 15 is involved in the flow in the width direction generated in the process of equalizing minute thickness unevenness (peaks and valleys).

As a result, when a soft sheet-like material 15 such as a non-woven fabric is used, for example, a streak-like wrinkle is apt to be formed when the sheet is bitten into the foamable thermoplastic resin sheet 14 during lamination and fusion and foamed in a later step. This causes a problem that the surface smoothness of the obtained foam is impaired. Further, for example, a brittle and easily breakable sheet material 1 such as glass paper
When 5 is used, there is a problem that the sheet-like material 15 is liable to be damaged or torn at the time of lamination, resulting in poor foaming and making it difficult to obtain a foam having good surface smoothness.

As described above, in the case of the method for producing a foam according to the above-mentioned disclosure, it is relatively difficult to obtain a foam having good surface smoothness, and the process of extruding the foamable thermoplastic resin sheet 14 and the sheet It takes a long time to stabilize the laminating / fusing step with the object 15 and the start loss increases, so that the efficiency of the obtained foam is low, and thus the productivity is low and the cost is high. There is a problem that becomes.

[0012]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a spindle having a cell shape of a foam oriented in a thickness direction. It is an object of the present invention to provide a method for producing a foamed composite sheet which exhibits strength and the like and is capable of obtaining a foamed composite sheet having excellent surface smoothness with good productivity.

[0013]

According to a first aspect of the present invention, there is provided a method for producing a foamed composite sheet, wherein the foamable sheet is formed on both sides of a foamable sheet comprising a thermoplastic resin composition containing a pyrolytic foaming agent. In a state where a sheet-like surface material having a strength capable of suppressing foaming force in the in-plane direction of the sheet when heated is laminated, the upper and lower sides are sandwiched between two continuous endless belts,
At a temperature that is equal to or higher than the melting point of the thermoplastic resin and equal to or lower than the decomposition temperature of the pyrolytic foaming agent, the foamable sheet and the sheet-like surface material are fused by heating at a pressure of 2 kPa or more for 60 seconds or more, Then, after foaming the foamable sheet by raising the temperature to a temperature equal to or higher than the decomposition temperature of the pyrolytic foaming agent,
It is characterized in that a foam having a cell shape oriented in the thickness direction is obtained through a step of cooling to a temperature lower than the melting point of the thermoplastic resin.

According to a second aspect of the present invention, there is provided a method for producing a foamed composite sheet according to the first aspect, wherein the thermoplastic resin composition comprises a polyolefin resin, a modifying monomer and a thermosetting resin. A composition containing a decomposition-type blowing agent, wherein the modifying monomer is selected from the group consisting of a dioxime compound, a bismaleimide compound, divinylbenzene, an allyl-based polyfunctional monomer, an acrylic-based polyfunctional monomer, and a quinone compound. It is characterized in that it is at least one kind of modifying monomer.

The thermoplastic resin contained in the thermoplastic resin composition constituting the foamable sheet used in the method for producing a foamed composite sheet according to claim 1 (hereinafter simply referred to as “production method”). Is not particularly limited as long as it is a resin that is melted when heated to a temperature equal to or higher than the melting point or the softening point. Examples thereof include a polyolefin resin such as polyethylene and polypropylene, polyvinyl chloride and chlorinated polychlorinated resin. Polyvinyl chloride resin such as vinyl, A
BS resins, polystyrene resins, polycarbonate resins, polyamide resins, polyvinylidene fluoride resins, polyphenylene sulfide resins, polysulfone resins, polyether ether ketone resins, and the like are used, and are preferably used. Polyolefin resins are particularly preferably used.

The thermoplastic resin may be a homopolymer or a copolymer, and the thermoplastic resin may be used alone or in combination of two or more. May be.

A thermally decomposable foaming agent contained in the thermoplastic resin composition constituting the foamable sheet used in the production method according to claim 1 (hereinafter simply referred to as "foaming agent").
Is not particularly limited as long as it can generate a decomposition gas by heating to foam the thermoplastic resin, and is not particularly limited. For example, azodicarbonamide (AD
CA), benzenesulfonyl hydrazide, dinitrosopentamethylenetetramine, toluenesulfonyl hydrazide, 4,4-oxybis (benzenesulfonyl hydrazide) and the like, which are preferably used.
CA is particularly preferably used. These foaming agents may be used alone or in combination of two or more.

The amount of the foaming agent to be added may be appropriately set according to the type of the thermoplastic resin and the desired expansion ratio.
Although not particularly limited, it is generally preferred that the amount of the foaming agent be 1 to 50 parts by weight, more preferably 2 to 35 parts by weight, based on 100 parts by weight of the thermoplastic resin.

The above-mentioned foaming agent is a foaming agent which starts to decompose at a temperature not lower than the temperature at which the foaming agent is decomposed by heating, and generates a decomposed gas to foam the thermoplastic resin.
The temperature at which the foaming agent decomposes depends on the type of the foaming agent and whether or not a foaming aid is used in combination.
When no foaming aid is used in combination, the temperature is generally about 200 ° C.

[0020] In the production method according to the second aspect, the thermoplastic resin composition constituting the foamable sheet contains a polyolefin resin, a modifying monomer, and the above-mentioned foaming agent, and further comprises the above-mentioned modifying monomer. Is a dioxime compound, a bismaleimide compound, divinylbenzene,
At least one selected from the group consisting of allylic polyfunctional monomers, acrylic polyfunctional monomers and quinone compounds
A thermoplastic resin composition which is a kind of modifying monomer is used.

The polyolefin resin is not particularly limited as long as it is a homopolymer or a copolymer of an olefin monomer. Examples of the polyolefin resin include low-density polyethylene, high-density polyethylene, and linear low-density polyethylene. Polyethylene such as polyethylene, propylene homopolymer, propylene random polymer, polypropylene such as propylene block polymer, polybutene, ethylene-
Copolymers containing ethylene as a main component such as propylene copolymer, ethylene-propylene-diene terpolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, etc. And the like, and are preferably used. Among them, polyethylene and polypropylene are particularly preferably used. These polyolefin resins may be used alone or in combination of two or more.

Further, the polyolefin resin may contain another resin of less than 30% by weight based on the polyolefin resin. Examples of the other resin include, but are not particularly limited to, polystyrene and a styrene-based elastomer. These other resins may be used alone or in combination of two or more.

When the amount of the other resin added to the polyolefin resin is at least 30% by weight, the excellent properties of the polyolefin resin such as light weight, chemical resistance, flexibility and elasticity may be impaired, In addition, it may be difficult to secure a necessary melt viscosity during foaming.

In the thermoplastic resin composition according to the second aspect, at least one selected from the group consisting of a dioxime compound, a bismaleimide compound, divinylbenzene, an allyl polyfunctional monomer, an acrylic polyfunctional monomer, and a quinone compound. Is contained.

When foaming a polyolefin resin using the above-mentioned foaming agent, the polyolefin resin must have a certain degree of viscosity and strength in a molten state. However, ordinary polyolefin-based resins have low viscosity and strength at the time of melting, and when bubbles are generated by a foaming agent or the like and foamed, the generated bubbles lose foam internal pressure and break. As a result, there is a problem that a good foam cannot be obtained.

For this reason, a method has been heretofore performed in which a polyolefin resin is previously crosslinked before foaming to improve its melt viscosity and melt strength, and then foamed after being brought into a state capable of withstanding the foaming internal pressure. However, in the case of this method, although the crosslinked polyolefin-based resin melts and softens, there is a problem that its fluidity is significantly reduced.

However, in the present invention, since the modifying monomer having two or more functional groups capable of radically reacting with the polyolefin resin is added to the polyolefin resin as the main component, the polyolefin resin is modified. A finely crosslinked structure is formed by the reaction with the monomer for use, and has both the necessary melt viscosity and melt strength at the time of foaming. Therefore, the above problems are solved, and a foam having excellent characteristics can be obtained.

The dioxime compound which can be used as a modifying monomer is a compound having two or more substituted oxime groups in the molecule in which an oxime group or its hydrogen group is substituted with another atomic group such as a hydrocarbon group. Good,
For example, p-quinone dioxime, p, p'-dibenzoylquinone dioxime and the like can be mentioned. These dioxime compounds may be used alone or in combination of two or more.

As the bismaleimide compound which can be used as a modifying monomer, a maleimide structure is contained in a molecule.
Any number of compounds may be used, for example, N, N'-
Examples include p-phenylenebismaleimide, N, N'-m-phenylenebismaleimide, diphenylmethanebismaleimide, and polymaleimide. These bismaleimide compounds may be used alone or in combination of two or more.

Examples of divinylbenzene which can be used as a modifying monomer include o-divinylbenzene,
m-divinylbenzene, p-divinylbenzene and the like. These divinylbenzenes may be used alone or in combination of two or more.

The allyl-based polyfunctional monomer which can be used as a modifying monomer may be any compound having two or more allyl groups in the molecule, such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, diallyl. Chlorendate and the like. These allyl-based polyfunctional monomers may be used alone or in combination of two or more.

Examples of the acrylic polyfunctional monomer that can be used as a modifying monomer include a di (meth) acrylic compound, a tri (meth) acrylic compound, and a tetra (meth) acrylic compound. These mean compounds having two, three, and four (meth) acryl groups in the molecule, for example, compounds having two, three, and four (meth) acryloyloxy groups in the molecule. Is applicable. These acrylic polyfunctional monomers may be used alone or in combination of two or more.
In addition, "(meth) acryl" here means "acryl"
Or "methacrylic".

Examples of the di (meth) acryl compound having two (meth) acryloyloxy groups in the molecule include alkanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, and propylene glycol di (meth) acrylate. Acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, di (meth) acrylate adduct of bisphenol A with ethylene glycol And di (meth) acrylate of a propylene glycol adduct of bisphenol A. These di (meth) acryl compounds having two (meth) acryloyloxy groups in the molecule may be used alone or in combination of two or more.

Examples of the tri (meth) acryl compound having three (meth) acryloyloxy groups in the molecule include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate,
Trimethylolpropane ethylene oxide-added tri (meth) acrylate, glycerin propylene oxide-added tri (meth) acrylate, tri (meth) acryloyloxyethyl phosphate and the like can be mentioned. These tri (meth) acryl compounds having three (meth) acryloyloxy groups in the molecule may be used alone or in combination of two or more.

As the tetra (meth) acryl compound having four (meth) acryloyloxy groups in the molecule,
For example, pentaerythritol tetra (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate and the like can be mentioned. These tetra (meth) acryl compounds having four (meth) acryloyloxy groups in the molecule may be used alone or in combination of two or more.

Examples of the quinone compound which can be used as the modifying monomer include hydroquinone, p-benzoquinone, tetrachloro-p-benzoquinone and the like. These quinone compounds may be used alone or in combination of two or more.

In the second aspect, the amount of the modifying monomer added to the polyolefin resin may be appropriately set according to the type of the polyolefin resin or the modifying monomer, and is not particularly limited. Generally, it is preferably 0.05 to 5 parts by weight, more preferably 0.2 to 2 parts by weight, of the modifying monomer based on 100 parts by weight of the polyolefin resin.

If the amount of the modifying monomer is less than 0.05 part by weight based on 100 parts by weight of the polyolefin resin, the melt viscosity and melt strength required during foaming may not be effectively imparted. System resin 100
If the amount of the modifying monomer to 5 parts by weight exceeds 5 parts by weight, the degree of cross-linking due to the reaction between the polyolefin resin and the modifying monomer becomes too high, and the extrudability during foamable sheet production deteriorates, The uniform kneading of the foaming agent becomes difficult, and the gel fraction is unnecessarily increased, and the quality and recyclability of the foam may be impaired. In addition, an excessive amount of the modifying monomer may remain as an unreacted substance in the foamed composite sheet, giving an undesired irritation to the human body, or lowering the product efficiency with respect to the raw material input amount.

The foaming agent is contained in the thermoplastic resin composition according to the second aspect. The kind and amount of the foaming agent may be the same as those of the thermoplastic resin composition in the first aspect.

The thermoplastic resin composition according to the present invention may contain an organic peroxide, if necessary.

The organic peroxide may be any one which is generally used for a graft reaction of a polyolefin resin, such as benzoyl peroxide, 2,4
-Dichlorobenzoyl peroxide, t-butylperoxyacetate, t-butylperoxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,
5-di (t-butylperoxy) hexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 and the like. These organic peroxides may be used alone or in combination of two or more.

The amount of the organic peroxide to be added is not particularly limited, but is preferably 0.001 to 0.5 parts by weight of the organic peroxide with respect to 100 parts by weight of the polyolefin resin. Preferably it is 0.005 to 0.15 parts by weight.

If the amount of the organic peroxide is less than 0.001 part by weight based on 100 parts by weight of the polyolefin resin, the conversion rate of the graft reaction of the polyolefin resin may be insufficient. Resin 10
When the addition amount of the organic peroxide with respect to 0 parts by weight exceeds 0.5 parts by weight, particularly when the polyolefin-based resin is polypropylene, so-called β-cleavage occurs remarkably, causing deterioration in the physical properties of the thermoplastic resin composition or melting. Poor foaming due to a decrease in viscosity may occur.

In the present invention, first, a composition comprising a polyolefin resin, a modifying monomer and a predetermined amount of an organic peroxide to be added as required is prepared by using a kneading device such as a screw extruder or a kneader. The product is melt-kneaded and a graft reaction is performed on the polyolefin-based resin to produce a grafted polyolefin-based resin (hereinafter, referred to as “modified polyolefin-based resin”).

The melt kneading temperature is 170 ° C. or higher and the decomposition temperature of the polyolefin resin is lower than 170 ° C.
Specifically, the temperature is preferably from 170 to 250 ° C, more preferably from 200 to 250 ° C. If the melt-kneading temperature is lower than 170 ° C., the expansion ratio of the obtained foam may not be sufficiently high, and if it exceeds 250 ° C., the polyolefin-based resin is easily decomposed.

The above-mentioned modified polyolefin-based resin may be further melt-kneaded with the same or different polyolefin-based resin or another thermoplastic resin. The kind and amount of the same or different polyolefin-based resin or other thermoplastic resin to be melt-kneaded are determined according to the moldability and appearance of the foamable sheet obtained by the method described below, and the adhesion to the sheet-like surface material described later. And the like, and the expansion ratio, mechanical properties, thermal properties, cell shape, and the like of the finally obtained foamed composite sheet may be appropriately set.

The method of adding the blowing agent to the thermoplastic resin used in the first aspect or the modified polyolefin resin used in the second aspect is not particularly limited, and examples thereof include a thermoplastic resin and a modified polyolefin. A method of melt-kneading a foaming agent by post-adding a foaming agent to a resin, or a melt-kneading of a thermoplastic resin or a polyolefin resin and a foaming agent in advance to prepare a masterbatch of a foaming agent. A method of melting and kneading a thermoplastic resin or a modified polyolefin-based resin is exemplified. The melt-kneading of the composition containing a blowing agent is preferably performed at a temperature equal to or lower than the decomposition temperature of the blowing agent.

The thermoplastic resin composition used in claim 1 or the thermoplastic resin composition (modified polyolefin resin composition) used in claim 2 can achieve the object of the present invention in addition to the essential components. Foaming aid, filler, tackifier, softener, plasticizer, surfactant, coupling agent, antioxidant (antiaging agent), heat stabilizer, light stabilizer One or more of various additives such as an agent, an ultraviolet absorber, a colorant, a lubricant, an antistatic agent, and a flame retardant may be added.

[0049]

Next, embodiments of the present invention (claims 1 and 2) will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an example of the production method of the present invention, and FIG. 2 is a cross-sectional view showing a foamed composite sheet obtained by the production method of the present invention.

In the production method of the present invention, first, the thermoplastic resin composition used in claim 1 or the thermoplastic resin composition (modified polyolefin resin composition) used in claim 2 is formed into a sheet shape. And foamable sheet 1
Is prepared.

The method of shaping the sheet is not particularly limited, and is generally used in plastic molding such as extrusion molding, press molding, blow molding, calendering molding, and injection molding. The extrusion method in which the thermoplastic resin composition discharged from a screw extruder is directly formed into a sheet shape is preferable because the productivity is excellent. In the case of this method, a continuous foamable sheet 1 having a certain width can be obtained.

In the production method of the present invention, when the foamable sheet 1 is heated on both sides in the in-plane direction (longitudinal direction and width direction) of the foamable sheet 1 obtained above. The foamed composite sheet 10 is obtained by laminating the sheet-like surface materials 2 having a strength capable of suppressing the foaming force.

The sheet-like surface material 2 is made of a foamable sheet 1
Since it is laminated and integrated, it is preferable to develop a certain degree of adhesiveness with the foamable sheet 1. However, even if it does not exhibit adhesiveness, it can be bonded by a physical anchor effect. And, through a thermoplastic resin film or the like that can exhibit an adhesive or adhesive or adhesive function,
Any material that can be bonded to the foamable sheet 1 may be used.

The sheet-like surface material 2 is made of a foam sheet 1
When the foamable sheet 1 is heated and foamed after being laminated and integrated, the foaming sheet 1 exerts a function of suppressing the foaming force in the in-plane direction of the foamable sheet 1. The foam 11 composed of the spindle-shaped cells 12 thus obtained can be obtained.

In order to effectively exert the function of suppressing the foaming force in the in-plane direction of the foamable sheet 1, the sheet-like surface material 2 is formed according to the expansion ratio desired to be imparted to the foam 11.
It preferably has a constant tensile strength.

That is, when the expansion ratio desired to be applied to the foam 11 is 5 times or less, the tensile strength of the sheet-like surface material 2 is preferably 0.01 to 0.04 MPa, and the expansion ratio is 5 to 5 MPa. In the case of 15 times, the tensile strength is 0.1.
The tensile strength is preferably 0.5 to 1 MPa when the expansion ratio is 15 times or more.
It is preferably MPa.

If the above-mentioned tensile strength of the sheet-like surface material 2 is less than the respective lower limits, the sheet-like surface material 2 is torn when the foamable sheet 1 is heated and foamed, so that the foaming force suppressing function is sufficiently obtained. If the tensile strength exceeds the respective upper limits, the flexibility of the obtained foamed composite sheet 10 may be poor.

Examples of the sheet-like surface material 2 which can be used in the present invention include a sheet-like material made of glass fiber or carbon fiber, and a woven or non-woven fabric made of paper, organic fiber or inorganic fiber. . Specifically, for example, glass paper or nonwoven fabric (surface mat) obtained by forming glass fiber, glass cloth woven with glass roving, and the like can be mentioned. Among them, glass paper is preferably used.

As the above-mentioned glass paper, for example, short fibers having a fiber length of 30 mm or less and glass fibers having a diameter of 8 to 15 μm are combined with each other by, for example, polyvinyl alcohol, saturated polyester resin, unsaturated polyester resin, acrylic resin, urethane resin, One bound with a binder made of an epoxy resin or the like can be used. The above glass paper is
Although not particularly limited, the thickness is 10 μm to 1 m
m and a weight of 10 to 50 g / m ² are preferred.

The sheet-like surface material 2 laminated on one surface of the foamable sheet 1 and the sheet-like surface material 2 laminated on the other surface may be the same or different types. It may be.

Next, the steps of manufacturing the foam composite sheet 10 according to the manufacturing method of the present invention will be described.

As shown in FIG. 1, first, the raw material of the foamable sheet 1 prepared in advance is loaded on a load roll 3 for preheating and fusing.
And a heating furnace 4 provided with a heating furnace 4 and a foaming furnace 6 for foaming, and the sheet-like surface material 2 having a width equal to or larger than the width of the raw material is supplied so as to overlap the raw material above and below. Further, in a state where the upper and lower portions of the superposed product of the foamable sheet 1 and the sheet-like surface material 2 are sandwiched between two continuous endless belts 7, the foamable sheet 1 and the sheet are heated by the hot air 5 from the heating furnace 4. The foamable sheet 1 and the sheet-like surface material 2 are laminated and fused to be integrated while being pressed with the weight rolls 3 while heating the surface-like material 2. The type of the continuous endless belt 7 is not particularly limited, and may be, for example, a belt obtained by impregnating glass fiber or aramid fiber with Teflon, or a metal belt such as a steel belt.

At this time, the heating temperature of the heating furnace 4 is not lower than the melting point of the thermoplastic resin contained in the foamable sheet 1 and not higher than the decomposition temperature of the foaming agent contained in the foamable sheet 1. Preferably, there is. If the heating temperature is lower than the melting point of the thermoplastic resin, the fusion of the foamable sheet 1 and the sheet-like surface material 2 may be insufficient, and if the heating temperature exceeds the decomposition temperature of the foaming agent. , Foam sheet 1
In a state where the sheet material 2 and the sheet-like surface material 2 are not sufficiently fused, early foaming may occur, and the foam 11 in which the cell shape is oriented in the thickness direction may not be obtained.

Further, the foamable sheet 1 and the sheet-like surface material 2
Is preferably performed under the pressure of 2 kPa or more by the load roll 3 for 60 seconds or more at the heating temperature. If the pressure is less than 2 kPa or the time is less than 60 seconds, the fusion between the foamable sheet 1 and the sheet-like surface material 2 may be insufficient. The upper limit of the pressing and the time is not particularly limited, but it is preferable that the pressing or the time is such that the foamable sheet 1 is not deformed.

It is preferable that a part of the load roll 3 is disposed at a position where the temperature of the foamable sheet 1 does not reach the melting point of the thermoplastic resin. By arranging in this manner, it is possible to perform such a pressure that the foamable sheet 1 and the sheet-like surface material 2 before fusion are fixed so that the positions thereof do not shift.

In the next step, the laminated body of the foamable sheet 1 and the sheet-like surface material 2 thus fused is supplied to the foaming furnace 6.
Is heated to a temperature equal to or higher than the decomposition temperature of the foaming agent, whereby the foamable sheet 1 is formed into a foamed laminate. The heating temperature at the time of the foaming is preferably a temperature equal to or lower than the decomposition temperature of the thermoplastic resin.

In the next step, the foam laminate obtained above is cooled by a cooling roll 8 and cut by a fixed-size cutter 9 to form a foam composite sheet 10 having a desired expansion ratio.

The foam composite sheet 10 thus obtained is
As shown in FIG. 2, a foam composite sheet 10 is obtained by using a foam 11 in which cells 12 each having a spindle shape are oriented in a thickness direction as a core material and a sheet-like surface material 2 laminated on both surfaces thereof.

[0069]

According to the production method of the present invention, when a foamable sheet is heated, a sheet-like surface material having a strength capable of suppressing a foaming force in an in-plane direction (longitudinal direction and width direction) of the sheet is formed. Since foaming is performed in a state of being laminated on both sides of the sheet, a foamed composite sheet comprising a foam having a spindle-shaped cell shape oriented in the thickness direction and the sheet-like surface material can be obtained. Since the foam has the specific cell shape, the foam composite sheet has excellent compressive strength, load resistance, bending strength, and the like.

Further, according to the production method of the present invention, a method is employed in which a raw material of a foamable sheet is prepared in advance, and a sheet-like surface material having the strength is laminated on both surfaces of the raw material.
In addition, since the fusion of the foamable sheet and the sheet-like surface material is performed at a specific temperature under a pressure of 2 kPa or more for 60 seconds or more, the extrusion lamination method disclosed in Japanese Patent Application Laid-Open No. 9-150431 is used. Unlike the case, the sheet-like surface material does not bite into the foamable sheet at the time of fusion, and does not cause streak-like wrinkles at the time of foaming. Therefore, a foam composite sheet having excellent surface smoothness can be obtained.

Further, according to the production method of the present invention, the start loss is greatly reduced as compared with the extrusion lamination method, so that a low-cost foam composite sheet can be obtained with good productivity.

[0072]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 (1) Preparation of Modified Polyolefin Resin In order to prepare a modified polyolefin resin, a model “B” was used.
T40 ”(Plastic Engineering Laboratory Co., Ltd.)
An axial screw extruder was used. This extruder is equipped with a self-wiping double-start screw whose L / D is 35, D
(Diameter) is 399 mm. The cylinder barrel is divided into a first barrel to a fourth barrel from the upstream side to the downstream side of the extruder, and a tip end of the fourth barrel is provided with a three-hole strand die (hereinafter, simply abbreviated as “three-hole die”). ing. In addition, a vacuum vent is provided in the fourth barrel in order to collect components (particularly, a modifying monomer) volatilized in the cylinder barrel. In the following operation, the temperature of the first barrel is set to 180 ° C., the second barrel, the third barrel,
The temperature of the fourth barrel and the three-hole die was set to 220 ° C., and the screw rotation speed was set to 150 rpm.

From a hopper provided at the rear end of the first barrel of the above-described extruder, a random polymer type polypropylene resin (trade name “EG
8 ", melt index 0.8, density 0.9 g / cm
³ , manufactured by Mitsubishi Chemical Corporation), and divinylbenzene (manufactured by Sankyo Chemical Co., Ltd.) as a modifying monomer. The polypropylene resin was charged at a rate of 10 kg / hour, and divinylbenzene was charged by a metering pump at a ratio of 1.5 parts by weight to 100 parts by weight of the polypropylene resin, and melt-kneaded to prepare a modified polypropylene resin. The modified polypropylene resin thus obtained was discharged from a three-hole die, cooled with water, and then cut with a pelletizer to obtain a pellet-shaped modified polypropylene resin.

(2) Preparation of Raw Material of Foamable Sheet In order to add an unmodified polypropylene resin and a foaming agent to the modified polypropylene resin obtained as described above, a model “TEX-44” (manufactured by Nippon Steel Works, Ltd.) ) A co-rotating twin screw extruder was used. This extruder is equipped with a self-wiping double-start screw, the L / D of which is 45.5, the D / D
Is 47 mm. The cylinder barrel is divided into a first barrel to a twelfth barrel from upstream to downstream of the extruder, and a T-die (width of 1,000 m) is provided at the tip of the twelfth barrel.
m, lip interval 0.6 mm).

Further, a side feeder is provided in the sixth barrel to supply the foaming agent, and a vacuum vent is provided in the eleventh barrel in order to recover the components (especially the foaming agent) volatilized in the cylinder barrel. Is provided. In the following operation, the first barrel is constantly cooled, the temperature of the first zone (second barrel to fourth barrel) is set to 150 ° C.,
The temperature of the zone (the fifth barrel to the eighth barrel) is 170 ° C.,
Set the temperature of the third zone (9th barrel to 12th barrel) to 18
The temperature of the fourth zone (T-die and adapter section) was set to 160 ° C., and the screw rotation speed was set to 40 rpm.

From the hopper provided at the rear end of the first barrel of the above-described extruder, the pellet-shaped modified polypropylene resin obtained in (1) and the unmodified homopolymer-type polypropylene resin (trade name “EA7 ”, Melt index 1.2, density 0.9 g / cm ³ , manufactured by Mitsubishi Chemical Corporation)
Was introduced. Both polypropylene resins were charged at a rate of 10 kg / hour (total 20 kg / hour),
1.2 kg of azodicarbonamide (ADCA) as a foaming agent from the side feeder provided in the barrel
/ Hour and melt-kneaded. The melt-kneaded product was extruded from a T-die and shaped into a sheet, and then cooled by a cooling roll to produce a continuous foamed sheet having a width of 1,000 mm and a thickness of 0.6 mm.

(3) Preparation of Foamed Composite Sheet Load roll 3, heating furnace 4, foaming furnace 6, as shown in FIG.
A heating and foaming machine equipped with a continuous endless belt 7 and a cooling roll 8 was used. Heating furnace 4
Is divided into two stages, a preheating furnace and a fusion furnace, and the foaming furnace 6 is divided into a foaming furnace I and a foaming furnace II. Furnace length is 4m
The length of each of the preheating furnace, the fusion furnace, the foaming furnace I and the foaming furnace II was 1 m. Further, a load roll 3 can be arbitrarily attached from the preheating furnace to the fusion furnace, and a maximum of 14 sets of upper and lower load rolls can be attached to each furnace. Further, the cooling zone has a total length of 2 m, and is provided with 10 sets of upper and lower cooling water circulating cooling rolls 8, and the gap between the upper and lower cooling rolls 8 is adjustable.

In Example 1, a heating and foaming machine in which 14 sets of upper and lower 30 kg load rolls 3 were attached to a fusing furnace in a heating furnace 4 was used. In this case, the load applied to the unit area of the raw material of the foamable sheet 1 was 4.2 kPa.

In Example 1, glass sheet (trade name “SUO-30”) was used as the sheet-like surface material 2.
B ", coefficient of linear expansion 1 × 10 ^-5 / ° C, weight 33.6 g / m
² , a thickness of 0.3 mm, a glass fiber length of 25 mm, and a glass fiber diameter of 9 μm) were used.

The heating furnace 4 and the foaming furnace 6 were both set to 220 ° C.
The surface temperature of the cooling rolls 8 was set to 25 ° C., and the gap between the upper and lower cooling rolls 8 was set to 6 mm.

The above-mentioned glass paper is continuously supplied to the heating furnace 4 in a state where the above-mentioned glass paper is superimposed on both sides of the original sheet (width: 1000 mm, thickness: 0.6 mm) of the foamable sheet 1 obtained in (2), It was integrated by fusion. Next, the mixture is heated and foamed in a foaming furnace 6, cooled to room temperature by a cooling roll 8, cut into a length of 1800 mm by a fixed-size cutter 9, and expanded into a foam composite sheet 10 (length 1800 mm, width 10
00 mm, thickness 0.6 mm). In the above-described manufacturing process, a thermocouple was attached to the surface of the raw material of the foamable sheet 1 and immediately before coming into contact with the load roll 3 and the heat roll 3.
The temperature immediately after contact with was measured.

(4) Evaluation The performance (foaming ratio, maximum bending load, presence or absence of floating of the surface material, production efficiency) of the foamable sheet obtained above was evaluated by the following methods. The results were as shown in Table 1.

Expansion ratio: After scraping off the sheet-like surface material from the expanded composite sheet with a cutter, JIS K-676
7 The apparent density of the foam was measured in accordance with “Polyethylene foam test method”, and the reciprocal thereof was used to calculate the expansion ratio (c
c / g).

Maximum bending load: JIS K-7221
In accordance with "Bending test method of rigid foamed plastic",
A bending test was performed on the foamed composite sheet cut into a length of 150 mm and a width of 50 mm, and the maximum bending load (N / 50 mm) was measured.

Presence / absence of surface material: The appearance of both surfaces of the foamed composite sheet was visually observed to determine whether or not the sheet-like surface material was floating (peeled) from the foam.

Production efficiency: Production efficiency (% by weight) was calculated from the ratio of the amount of commercialized foam composite sheet to the total amount of raw materials used.

(Example 2) 20 kg in a fusion furnace in a heating furnace
A foam composite sheet was obtained in the same manner as in Example 1 except that a heating and foaming machine having 14 sets of load rolls was used. In this case, the load applied to the unit area of the raw material of the foamable sheet was 2.8 kPa.

(Comparative Example 1) 10 kg was added to the fusion furnace in the heating furnace.
A foam composite sheet was obtained in the same manner as in Example 1 except that a heating and foaming machine having 14 sets of load rolls was used. In this case, the load applied to the unit area of the raw material of the foamable sheet was 1.4 kPa.

(Comparative Example 2) Three half of the fusion furnace in the heating furnace
A foam composite sheet was obtained in the same manner as in Example 1 except that a heating foaming machine having seven sets of upper and lower load rolls of 0 kg was used, and the distance passing through the load rolls was set to 50 cm. In this case, the load applied to the unit area of the raw material of the foamable sheet was 2.1 kPa.

(Comparative Example 3) 30 kg in a preheating furnace in a heating furnace
A foam composite sheet was obtained in the same manner as in Example 1 except that a heating and foaming machine having 14 sets of load rolls was used. In this case, the load applied to the unit area of the raw material of the foamable sheet was 4.2 kPa.

(Comparative Example 4) The extruder “T” used in Example 1
EX-44 ”and two opposing rolls are placed immediately after
Immediately after the raw sheet of the foamed sheet extruded in the same manner as in Example 1, the glass paper (sheet-like surface material) is overlapped on the upper and lower sides of the raw sheet immediately after passing through the T-die, and the foamable sheet is passed through the roll. And the lamination of the foamable sheet and the glass paper was simultaneously performed. Then
This laminate was introduced into the heating furnace used in Example 1, and the foamable sheet was heated and foamed to obtain a foamed composite sheet. still,
In this case, since no load roll was required, no load roll was attached to either the preheating furnace or the fusing furnace in the heating furnace.

The performance (expansion ratio, maximum bending load, presence / absence of surface material floating, production efficiency) of the foamed composite sheets obtained in Example 2 and Comparative Examples 1 to 4 was measured in Example 1.
The evaluation was performed in the same manner as in the above case. The results were as shown in Table 1. In addition, since the maximum bending load of the foam composite sheet obtained in Comparative Example 3 was extremely low and the glass paper (sheet-like surface material) floated (peeled) from the foam, the production efficiency was calculated. Did not.

[0094]

[Table 1]

As is clear from Table 1, the foamed composite sheets of Examples 1 and 2 according to the production method of the present invention exhibited excellent maximum bending load and surface smoothness, and also had high production efficiency. .

On the other hand, the fusion between the foamable sheet and the glass paper (sheet-like surface material) was less than 2 kPa (1.4 kPa).
kPa) The foam composite sheet of Comparative Example 1 performed under a pressure of
Further, the foamed composite sheet of Comparative Example 2 in which the fusion of the foamable sheet and the glass paper (sheet-like surface material) was performed with a pressing time of less than 60 seconds (30 seconds) had a low maximum bending strength,
Lifting of the glass paper (sheet-like surface material) from the foam was also observed, and the surface smoothness was poor. Also, the production efficiency was low.

Also, without attaching the load roll to the fusing furnace,
The foamed composite sheet of Comparative Example 3 produced using a heating foaming machine attached to a preheating furnace has an extremely low maximum bending load, and the glass paper (sheet-like surface material) floats sharply from the foam, which makes it practical. The calculation of production efficiency was not performed because it was missing.

Further, the foamed composite sheet of Comparative Example 4 produced by the extrusion laminating method was excellent in quality performance but low in production efficiency.

[0099]

As described above, according to the production method of the present invention, a foamed composite sheet exhibiting excellent compressive strength, load resistance, bending strength and the like and having excellent surface smoothness can be produced with high productivity. Can be obtained at

The foam composite sheet obtained by the production method of the present invention has excellent compressive strength, load resistance, bending strength, etc., and also has excellent surface smoothness. And core materials under floors, interior materials for automobiles and vehicles, various heat insulating materials, cushioning materials, floating materials and the like.

[0101]

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a production method of the present invention.

FIG. 2 is a cross-sectional view showing a foam composite sheet obtained by the production method of the present invention.

FIG. 3 is a schematic view showing a process of an extrusion lamination method.

FIG. 4 is a schematic view showing a state when a foamable thermoplastic resin sheet is sandwiched between rolls.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foamable sheet 2 Sheet-shaped surface material 3 Load roll 4 Heating furnace 5 Hot air 6 Foaming furnace 7 Continuous endless belt 8 Cooling roll 9 Fixed-size cutter 10 Foam composite sheet 11 Foam 12 Cell 13 Extrusion mold 14 Foamable thermoplastic resin Sheet 15 Sheet 16 Roll 17 Bank

Continued on the front page F-term (reference) 4F074 AA16 AA24 AD01 AD07 AD13 AD21 BA13 BB03 BB07 BB10 BB28 CA24 CA29 CC03X CC03Y CC04X CC05Z CC22X CC34Y DA20 DA32 DA33 DA42 DA59 4F212 AA03 AA11 AB02 AD04 AD08 AD16 AG03 AG20 AU09 AU09 UG02 UG05 UG07 UH06 UH18 UW05 4J002 BB001 BB031 BB041 BB121 BB141 BB151 BB171 BP021 EA046 EE056 EH076 ES016 EU026 FD146 FD32 GF00 GT00

Claims (2)

[Claims] 1. A strength capable of suppressing the foaming force in the in-plane direction of the foamable sheet when the foamable sheet is heated on both sides of the foamable sheet made of a thermoplastic resin composition containing a pyrolytic foaming agent. In the state where the sheet-like surface material having the above is laminated, the upper and lower sides are sandwiched between two continuous endless belts, and at a temperature not lower than the melting point of the thermoplastic resin and not higher than the decomposition temperature of the pyrolytic foaming agent, 2 kPa or higher The foamable sheet and the sheet-like surface material were fused by heating for 60 seconds or more under pressure, and then heated to a temperature equal to or higher than the decomposition temperature of the pyrolytic foaming agent to foam the foamable sheet. Thereafter, a method for producing a foamed composite sheet, characterized by obtaining a foam having a cell shape oriented in the thickness direction by passing through a step of cooling to a temperature equal to or lower than the melting point of the thermoplastic resin. 2. A thermoplastic resin composition comprising a polyolefin resin, a modifying monomer and a pyrolytic blowing agent, wherein the modifying monomer is a dioxime compound, a bismaleimide compound, divinylbenzene, The method for producing a foamed composite sheet according to claim 1, wherein the method is at least one kind of a modifying monomer selected from the group consisting of an allyl-based polyfunctional monomer, an acrylic-based polyfunctional monomer, and a quinone compound.