JP2001212832A - Method for continuously producing foamed resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for continuously producing a foamed resin which can produce the foamed resin in which an expandable thermosetting resin composition is filled with a filler stably and continuously without causing quality deterioration. SOLUTION: When a molding material 14 in which the composition is filled with the filler is expanded and cured, the material 14 is supplied to a continuously moving molding passage in which a resistance area 3 for preventing the back flow of the material 14, a foaming area 4 from a pressure increasing point to the end of foaming, and a curing area 5 from the end of foaming to the curing of the composition are formed in turn. In the resistance area 3, the material 14 is pressurized perpendicularly to the advance direction of the passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously producing a resin foam, which is suitable for continuously producing a foam molded article in which a filler is highly filled in a foamable thermosetting resin composition.

[0002]

2. Description of the Related Art Conventionally, wood and concrete have been widely used as construction materials. However, wood tends to be corroded and damaged, and has problems in durability such as deterioration of physical properties due to water absorption. On the other hand, concrete has excellent durability and strength, but has problems such as being very heavy and easily cracking due to vibration.

In order to address these problems, fiber-reinforced resin foams have been used as an alternative to the above wood and concrete. Those having sufficient mechanical properties such as breaking strength (bending strength, tensile strength, compressive strength, etc.) and hardness have been developed and used for various applications. However, since these use expensive continuous filaments, the cost is high, and depending on the outer wall or the application, a high breaking strength may not always be required.

For example, in Japanese Patent Application Laid-Open No. Hei 5-138797, a core material (which may contain a filler) made of a thermosetting resin foam is integrated with at least one surface side and an opposite surface side of the core material. There has been proposed a composite material composed of a thermally laminated resin material, wherein the surface material is made of a thermosetting resin foam reinforced by long fibers along the longitudinal direction.

Further, a method for producing a panel in which a filler is mixed in a resin composition for polyurethane foam has been proposed (JP-B-56-24613, JP-B-55-1).
8130, JP-A-50-109913, etc.).

As described above, it has been conventionally performed to add a relatively inexpensive filler to a foamable thermosetting resin composition to obtain a resin foam having improved hardness and self-holding property. At the time of molding, due to foaming of the thermosetting resin, the filled filler flows in the upstream direction of the line, and as a result, it is difficult to secure a predetermined filling rate of the filler.
In particular, there is a case where fatal quality deterioration is brought about for a product that develops physical properties by highly filling the filler.

That is, when a molding material in which a filler is highly filled in a foamable thermosetting resin composition is supplied to a continuously moving molding passage and foamed and cured, a resin interposed in a gap between the fillers is formed. In the composition, the generation of foaming gas and the increase in viscosity are simultaneously performed from the time when the reaction starts, and cells are formed. At the stage when the gap is filled up, foaming tends to proceed in the gap of the filler upstream of the foaming area, but a foaming force is generated due to the flow path resistance of the gap. This foaming force pushes the filler on the upstream side and tends to return to the upstream. As a result, the filling rate of the filler of the molding material is reduced, resulting in quality deterioration.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and provides a stable and continuous resin foam obtained by highly filling a foamable thermosetting resin composition with a filler without deteriorating the quality. It is an object of the present invention to provide a method for continuously producing a resin foam which can be produced at a low cost.

[0009]

According to a first aspect of the present invention, there is provided a method for continuously producing a resin foam (hereinafter referred to as "the present invention"), comprising a molding material in which a foaming thermosetting resin composition is highly filled with a filler. In the foaming thermosetting resin composition, a molding material highly filled with a filler, in foaming and curing, from the resistance zone for preventing the backflow of the molding material, from the point where the pressure starts to rise, until the foaming is completed Are supplied to a continuously moving molding passage provided in this order with a foaming region and a curing region from the end of foaming until the thermosetting resin composition is cured.

According to a second aspect of the present invention, in the present invention, in the present invention, the molding material in the molding passage is pressed in the resistance region in a direction orthogonal to the moving direction of the molding passage. Things.

The foamable thermosetting resin composition used in the present invention comprises a thermosetting resin and a foaming agent.

The thermosetting resin is not particularly restricted but includes, for example, urethane resins, phenol resins, unsaturated polyester resins, epoxy resins and the like. These may be used alone or in combination of two or more. In particular, urethane-based resins are preferably used because they have relatively high mechanical strength as a foam and have excellent non-water-absorbing properties because they form closed cells during foaming.

Examples of the foaming agent include carbon dioxide,
Physical foaming agents such as chlorofluorocarbons and pentane; thermal decomposition foaming agents such as azo compounds and baking soda; and reactive foaming agents such as by-products such as decomposition gas generated during the curing reaction of the thermosetting resin. . When a urethane resin is used as the thermosetting resin, water can be used as a reactive foaming agent, and carbon dioxide gas generated by the reaction between isocyanate and water contributes to foaming.

In particular, in recent years, regulations have been tightened because chlorofluorocarbons may destroy the ozone layer. Therefore, in the case of urethane resins, it is preferable to use water. In addition, it is preferable to mix the above-mentioned foaming agent with other components forming the foamable thermosetting resin composition in advance, since foaming is performed uniformly.

The foamable thermosetting resin composition used in the present invention may contain, if necessary, a catalyst, a foam stabilizer, a foaming aid, a coloring agent, an ultraviolet absorber, an antioxidant, a crosslinking agent, a stabilizer, Plasticizers, flame retardants and the like may be added.

The filler used in the present invention does not melt in the above-mentioned thermosetting resin, but when dispersed in the thermosetting resin,
Are bonded to each other via a thermosetting resin,
Depending on the purpose of filling, it is to impart the desired properties to the matrix, compressive strength, to increase the rigidity, to increase the hardness, to reduce the raw material cost as a bulking material, to impart vibration damping action, Amorphous substances such as rock powder, glass powder, calcium silicate, pulverized cement concrete, silica sand, calcium carbonate, fly ash, etc .; , Wollastonite and other inorganic short fibrous materials; vermiculite, perlite, expanded shale, fly ash hollow powder and other inorganic hollow particles; pulverization of plastic products such as vinyl chloride resin pipes and polyethylene terephthalate bottles Dry matter and sludge from sludge treatment plant; inorganic fiber such as glass fiber; organic fiber; metal fiber; Plastic ground material, fiber-reinforced resin pulverized such fiber-reinforced rigid polyurethane foam pulverized product; rubber; like foam pulverized. These may be used alone or in combination of two or more.

The above-mentioned filler is preferably filled at a high level in a state where the powders and granules are in contact with each other. By doing so, for example, the effect of improving the physical properties represented by compressive strength and the like, and the low cost can be obtained. The effect of cost reduction and the like by high filling of a simple filler is exhibited. The volume filling rate of the filler varies depending on the shape, particle size, particle size distribution, and the like of the filler used. For example, in the case of an amorphous powder such as silica sand, 45 to 70 vol.
1% is preferable, and in the case of a sphere, 50 to 75 vol%
Is preferred.

The above-mentioned volume filling ratio is a value calculated from an apparent specific gravity, and is obtained, for example, from the density measured in a liquid that cannot enter the pores. This corresponds to the value calculated from the specific gravity, and in the case of open cells, the bubbles are not included in the volume.

In the present invention, as described above, in order to highly fill a foamable thermosetting resin composition with a filler, for example,
First, a foamable thermosetting resin composition and a filler are mixed,
The mixture is compacted. The mixing method is not particularly limited, and for example, a continuous mixer such as a clay kneader; a batch mixer such as a mixer / kneader can be used.
The consolidation method is not particularly limited, and for example, an intermittent press method, a roll method, a plunger method, an endless belt method, a slat conveyor method, and the like can be used. From the viewpoint of being possible, a roll system, an endless belt system, and a slat conveyor system are preferred. In addition, if the material after mixing has a property of recoverability after compaction, an endless belt system and a slat conveyor system which can be formed while maintaining the compacted state are preferable.

In the present invention, first, a molding material in which the above-mentioned expandable thermosetting resin composition is highly filled with a filler is supplied to a continuously moving molding passage. The continuously moving molding passage is formed of, for example, a cylindrical cavity formed by an endless belt system, a slat conveyor system, or the like.
The material of the endless belt is not particularly limited as long as it has heat resistance and does not inhibit the foaming and curing reaction, and examples thereof include steel, resin, and rubber. If the cross-sectional shape of the obtained molded product is square, four belts are installed at positions corresponding to the four side surfaces of the molded product. When a urethane-based resin is used as the foamable thermosetting resin composition, an endless belt system is preferred from the viewpoint of adhesion to the wall surface of the molding passage. On the other hand, in the slat conveyor system, it is easy to give an irregular shape in the longitudinal direction. In addition, endless belt method,
When the slat conveyor system is used, the slat conveyor system can also be used for consolidation of the mixture of the foamable thermosetting resin composition and the filler.

In the above-mentioned molding passage, a resistance region for preventing a backflow of the molding material, from the point at which the pressure starts to increase after the foaming thermosetting resin composition fills the gap between the fillers, from the point at which the foaming ends. And a cured region from the end of the foaming to the curing of the thermosetting resin composition are provided in this order.

The resistance region is provided for the purpose of preventing the backflow of the molding material, for example, in order to suppress the movement of the upstream filler due to the foaming pressure generated in the foaming region downstream in the direction of travel of the molding material. It is a thing. That is, in the resistance region, in order to prevent the backflow of the molding material, it is necessary to develop a resistance greater than the foaming pressure, and specific examples include the following methods. A method of obtaining a resistance force by contact pressure between the compacted molding material and the molding passage wall portion, for example, by applying a press load in a direction perpendicular to the direction of travel of the molding passage, and applying a press load to the molding passage. Pressurizing molding material.

In the case of the above, there is a contact pressure inherent to the molding material,
The resistance of the contact pressure can be adjusted by the length of the resistance region according to the molding material. In the case of (1), an arbitrary resistance force can be expressed by changing the pressing pressure, and the ability to cope with the molding material is high. The method for applying the press pressure is not particularly limited, but a simple method is to provide a pressure receiving segment on the back surface of the belt or the slat and mechanically apply a load thereto.

The foaming zone and the hardening zone are areas in which foaming and hardening reactions of the compacted molding material are performed, and the foaming zone usually requires a pressure-resistant structure against foaming pressure.

It is preferable that each of the resistance region, the foaming region, and the hardening region has a temperature control function.
The temperature control method is not particularly limited.For example, a metal segment is provided in each region so as to be in contact with the outer periphery of an endless belt forming a molding passage, a slat conveyor, and the like. A method of adjusting the temperature of the molding passage by adjusting the temperature, a method of applying hot air / cold air to each region, and the like can be given. Also, if necessary,
By providing a cooling area downstream of the hardening area, the line length can be shortened.

The molding passage is preferably driven by an endless belt or the like itself forming the passage, but a take-up machine is provided downstream in the traveling direction to supply the molding material onto the base material at the start of production. By taking off the substrate, the cured molded product is taken out, and the endless belt or the like can be driven by conveying the molding material.

In the above-mentioned molding passage, a dam plate may be provided at the tip of the molding material at the start of production. By doing so, it is possible to prevent the molding material introduced into the molding passage from leaking in front of the endless belt or the like. The barrier plate is removed when the curing of the molding material is completed, and the molded product is drawn into the take-off machine, so that continuous molding can be stably performed.

(Function) In the method for continuously producing a resin foam according to the present invention, the backflow of the molding material is prevented when the molding material in which the filler is highly filled in the foamable thermosetting resin composition is foamed and cured. The resistance zone to be subjected to, from the point where the pressure starts to rise, the foaming zone until the foaming is completed, and the curing zone from the end of the foaming until the thermosetting resin composition is cured, are provided in this order, continuously. Is supplied to the molding passage that moves to the next position.

The gap between the fillers supplied to the molding passage is fine, and a foaming force is exhibited by the flow passage resistance when the resin viscosity increases during foaming, but a resistance region for preventing a backflow of the molding material is provided. Accordingly, the upstream movement of the filler due to the foaming force is suppressed, and the resin foam can be stably and continuously manufactured without deteriorating the quality.

[0030] In particular, as described in claim 2, by pressing the molding material in the molding passage in the resistance region in a direction orthogonal to the advancing direction of the molding passage, the fillers are mutually separated. It comes into contact with the compacted state, and the force in the direction perpendicular to the direction of travel of the molding passage can be transmitted to the entire resistance area,
The upstream movement of the filler due to the foaming force is further suppressed.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic side view showing one example of a production apparatus used in the continuous production method of a resin foam of the present invention. In FIG. 1, 1 is a molding material introduction area, 2 is a consolidation area,
Reference numeral 3 denotes a resistance zone, 31 denotes a belt pressing device, 4 denotes a foaming zone, 5 denotes a hardening zone, and 7 denotes an endless belt. As shown in FIG. 1, the manufacturing apparatus used in the present invention comprises a molding material introduction region 1, a consolidation region 2, a resistance region 3, a foaming region 4, a hardening region 5, and a cooling region 6. Endless belt 7 up to cooling zone 6
Are connected by Hereinafter, the continuous production method of the resin foam of the present invention will be sequentially described for each region. The molding passage is a space in which the molding material 14 is filled in the endless belt 7 in the figure.

(1) Molding Material Introducing Area In the method for continuously producing a resin foam of the present invention, the resin tank 1
From 1, the foaming thermosetting resin composition is supplied from the resin supply pump P to the continuous mixer 13 from the filler silo 12 by the filler supply feeder F. Then, the shaft of the continuous mixer 13 is rotated to mix the foamable thermosetting resin composition and the filler, and the obtained molding material 14 is manufactured by using a bottom surface and both side surfaces (not shown). And is conveyed to the consolidation area 2.

(2) Consolidation Area The consolidation area 2 of the above-mentioned manufacturing apparatus is composed of a bottom surface and both side surfaces (not shown) and an inclined portion 21 of the endless belt 7 provided above. Conveyed molding material 1
4 is reduced in thickness in the vertical direction by the inclined portion 21 and is compacted. At this time, the inclination angle of the inclined portion 21 is set so that the molding material 14 does not stay. At this time, both side surfaces of the consolidation area 2 may be inclined so as to gradually narrow in the direction in which the molding material 14 advances. Then, when being conveyed from the consolidation area 2 to the resistance area 3, the molding material 14
Is compacted to the cross-sectional dimensions of the foam to be produced.

(3) Resistance area In the resistance area 3, the compacted molding material 14 applies a predetermined pressing pressure in a direction orthogonal to the traveling direction.
Given from 1. Then, a resistance force is generated between the fillers and between the filler and the endless belt 7. What may be affected by the foaming force from the foaming zone 4 described later is the filler in the upstream resistance zone 3 that is not completely fixed. However, since the above-described resistance acts on the filler in the resistance region 3, the filler does not move due to the foaming force.

(4) Foaming Zone The molding material 14 that has passed through the resistance zone 3 is conveyed to the foaming zone 4. Here, the decomposition and volatilization of the foaming agent are gradually progressing, and the gap between the fillers in the foaming area 4 is filled with the foamable thermosetting resin composition and the foaming gas, and the foaming force is generated. . With this foaming force, as described above, the movement of the filler in the resistance region 3 does not occur. Therefore, the molding material 14 is conveyed to the hardening zone 5 while maintaining a predetermined filling rate.

(5) Curing Zone In the curing zone 5, a polymerization reaction of the thermosetting resin composition containing a foaming gas is performed, and a resin foam is obtained.

(6) Cooling Zone The polymerization reaction in the curing zone 5 is usually an exothermic reaction, and the temperature of the resin foam in which the molding material 14 has been foamed and cured rises. Therefore, it is preferable to provide a cooling zone 6 as needed to cool to a required temperature. By lowering the surface temperature of the resin foam and increasing the surface rigidity in this way, it is possible to suppress the swelling phenomenon due to the foaming energy remaining inside the resin foam.

(7) Taking and Cutting After that, the resin foam passes through the taking-up machine 8 and is cut into a desired length by the cutting machine 9.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail based on embodiments.

Example 1 As a foamable thermosetting resin composition, polyether polyol (having a hydroxyl value of 390) 10
0 parts by weight, 110 parts by weight of polymethylene polyphenyl polyisocyanate (hereinafter simply referred to as "parts"),
0.5 part of a silicone oil agent for foam control, 0.3 part of water, and 0.05 part of dibutyltin laurate as a reaction catalyst are supplied to the resin tank 11 of the manufacturing apparatus shown in FIG. While being supplied to the mixer 13, No. 7 silica sand as a filler is supplied from the filler silo 12 by the filler supply feeder F to the continuous mixer 13 so that the volume filling rate is 55%, and mixed. A molding material 14 was obtained. Then, the obtained molding material 14 is supplied to the manufacturing apparatus main body (1 to 7 in FIG. 1), and the consolidation having the inclined portion 21 with the inclination angle of 5 ° is moved while moving in the molding passage at a conveying speed of 1 m / min. Zone 2, room temperature resistance zone 3, 50 in which the length of the portion having a resistance greater than the foaming pressure is 2,000 mm
C., passed through a foaming zone 4 at 80.degree. C., a hardening zone 5 at 80.degree. C., and a cooling zone 6 at room temperature.
A resin foam having a thickness of 00 mm and a height of 100 mm was obtained.

(Example 2) No. 3 silica sand and No. 7 silica sand were used as filler, and the volume filling ratio of the filler was 65% (including 52% of No. 3 silica sand and 13% of No. 7 silica sand) in the resistance region. The length of the part having a resistance greater than the foaming pressure is 2,000 m
m, and a press pressure of 0.1 MPa from the pressurizing device 31.
A resin foam was obtained in the same manner as in Example 1 except that the molding material was pressurized through the endless belt 7 with the following pressure.

Comparative Example 1 A resin foam was obtained in the same manner as in Example 1 except that the resistance region 3 was eliminated.

(Comparative Example 2) The same procedure as in Example 2 was carried out except that no press pressure was applied by the pressurizing device 31 (the length of the portion having a resistance greater than the foaming pressure was 0 mm).
A resin foam was obtained.

(Evaluation of Resin Foam) The resin foams obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to the following evaluations, and the results are shown in Table 1.

Filling Ratio of Filler The obtained resin foam was placed in a muffle furnace at 750 ° C. for 60 hours.
After baking for minutes, removing organic components, remaining inorganic substances,
That is, the weight of the filler component was measured and calculated.

Compressive Strength The compressive strength of the obtained resin foam was measured in accordance with JIS K6911.
It measured according to.

Backflow of molding material The above-mentioned resin foam was manufactured continuously for 3 hours, and during this period, near the entrance of the consolidation area 2, the backflow of the molding material, that is, the presence or absence of overflow was visually observed.

[0049]

[Table 1]

[0050]

As described above, the present invention has a structure as described above, so that a resin foam made of a molding material in which a foaming thermosetting resin composition is highly filled with a filler can be stably produced without deteriorating the quality. And it can be manufactured continuously.

Further, by pressing the molding material in the molding passage in the resistance region in a direction perpendicular to the direction of travel of the molding passage, the resin foam made of the molding material can be further stably and securely formed. It can be manufactured continuously.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of a production apparatus used for a continuous production method of a resin foam of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding material introduction area 2 Consolidation area 3 Resistance area 31 Belt pressing device 4 Foaming area 5 Hardening area 7 Endless belt

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 06 B29C 67/22

Claims (2)

[Claims] 1. When foaming and curing a molding material in which a filler is highly filled in a foamable thermosetting resin composition, foaming is performed from a resistance region for preventing backflow of the molding material and a point where pressure starts to rise. The foaming area until the completion, the curing area until the thermosetting resin composition is cured after the foaming is completed, and the curing area provided in this order, is supplied to a continuously moving molding passage. Continuous production method of resin foam. 2. The continuous resin foam according to claim 1, wherein the molding material in the molding passage is pressurized in the resistance region in a direction orthogonal to a traveling direction of the molding passage. Production method.