JPH0446941A - Preparation of phenol foam and phenol foam prepared therewith - Google Patents

Abstract

PURPOSE:To improve the friability, shrinkage during foaming, and permanent set of a phenol foam by placing a fiber or fabric to a phenol resin compsn. and irradiating the compsn. with a high-frequency wave to foam and cure the compsn. CONSTITUTION:The title foam is prepd. by placing a fiber or fabric into and/or on the surface of a phenol resin compsn. and irradiating the compsn. with a high frequency wave to foam and cure the compsn. The fiber or fabric pref. comprises a composite fiber consisting of one component which has a low dielectric constant and hardly generates heat when irradiated with the high-frequency wave and the other component which has a high dielectric constant and easily generates heat when irradiated. When the compsn. contains a highly water- absorbent resin, it can be foamed and cured more effectively by the irradiation, giving a phenol foam having further improved friability and surface uniformity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a phenol foam and a phenol foam.

[Prior Art] Phenol foam is lightweight and has excellent heat and sound insulation properties, as well as excellent performance such as fire resistance, solvent resistance, low temperature resistance, and dimensional stability. It is attracting attention as a material for various constructions such as panels due to its safety and economic efficiency.

The method for manufacturing phenolic foam is to heat, foam, and harden a phenolic resin compound that is a phenolic resin initial condensate called resol or novolac mixed with a curing agent, foaming agent, foam stabilizer, coloring agent, etc. When heated, the foaming agent contained in the compound vaporizes to form a foamed structure, and the polymerization reaction of the phenolic resin initial condensate progresses to form a foam. There are two main methods for foaming and curing by heating.

That is, there are (1) an external heating method in which the phenolic resin compound is heated from the outside, and (2) a so-called internal heating method in which the compound itself generates heat by irradiating high frequency waves including microwaves.

Among these methods, external heating methods include electric heating, steam,
Thermal energy from a heating source such as gas is supplied from the outside, and foaming starts from the outer layer of the compound and then progresses to the inside, with the outer layer having thermal insulation properties at the initial stage of foaming. It forms a foam structure that makes it difficult for heat to be transferred to the inside. Therefore, thermal efficiency, i.e. foaming,
This is not preferable because the curing efficiency becomes extremely poor and causes a decrease in productivity. In addition, since foaming starts from the outer layer, the density in the thickness direction of the foam is low in the outer layer and high in the inner layer, resulting in a foam structure that is one of the factors that makes phenol foam brittle. Undesirable.

On the other hand, the internal heating method, which aims at foaming and curing by irradiating high frequency waves including microwaves, overcomes the drawbacks of the external heating method described above in terms of thermal efficiency and uniformity of foam density.
This is the preferred method. As a specific proposal, Japanese Patent Application Laid-Open No. 59-32417 discloses a method of generating high frequency waves by interposing conductive filaments in a foamable synthetic resin to generate foam. Also, JP-A-60-2628
No. 35 discloses a method in which a foamable resin is melted by preheating and then foamed by a heating method including microwave irradiation. Also, JP-A-6.1-25
No. 81.0 discloses a method of foaming a gelled phenol liquid film by irradiating it with microwaves by heating a metal molded plate and using far infrared rays. The method of manufacturing a foam by irradiating microwaves or high frequency waves as described above is well known.

However, with all of these methods, shrinkage and stickiness occur during foaming, and dimensions are likely to change.Furthermore, unevenness may occur on the surface of the foam, and the overall shape of the foam may be uneven due to uneven irradiation. It has disadvantages inherent to high-frequency irradiation, such as being susceptible to corrosion, and also has the problem of brittleness, which is not preferable.

[Problems to be Solved by the Invention] The present invention provides a foaming and curing method that improves the brittleness of the phenol foam and also improves the above-mentioned problems such as shrinkage and stiffness during foaming in the production of phenol foam. The purpose is to provide.

[Means to solve the problem] The present invention has the following configuration.

That is, the method for producing a phenol foam according to the present invention includes disposing fibers and/or fabrics inside and/or on the surface of a phenol resin compound, and then irradiating the phenol resin with high frequency to foam and harden the phenol resin. A method for producing a phenolic foam, which is preferably characterized in that the fiber and/or fabric comprises a composite fiber composed of two or more composite components having different dielectric constants. The conjugate fiber is a core-sheath type conjugate fiber, and the dielectric constant of the core component is smaller than the dielectric constant of the sheath component.

In addition, the method for producing a phenol foam is characterized by mixing a super absorbent resin in a phenol resin compound, and then irradiating the phenol resin with high frequency to foam and harden the phenol resin. This method of producing a phenol foam is characterized by mixing carbon into a compound and then irradiating the phenol resin with high frequency to foam and harden the phenol resin. Furthermore, after arranging fibers and/or fabrics inside and/or on the surface of the phenolic resin compound and mixing super absorbent resin and/or carbon, the phenolic resin is foamed and hardened by irradiation with high frequency. This is a method for producing a phenol foam characterized by the following.

Furthermore, the phenol foam according to the present invention is a phenol foam foamed and cured by high frequency irradiation, and the inside and/or surface of the foam is reinforced with fibers and/or fabrics. A phenol foam characterized in that the phenol foam preferably comprises a composite fiber whose fibers and/or fabrics are composed of two or more composite components having different dielectric constants. Further, the composite fiber is a core-sheath type composite fiber, and the dielectric constant of the core component is smaller than the dielectric constant of the sheath component.

Further, it is a phenol foam that is foamed and cured by high frequency irradiation, and is characterized in that a super absorbent resin is mixed in the foam; The present invention is a hardened phenol foam characterized in that carbon is mixed in the foam. Alternatively, a phenol foam foamed and cured by high-frequency irradiation, the interior and/or surface of the foam is reinforced with fibers and/or fabric, and the foam has high water absorption properties. The present invention relates to a phenol foam characterized by containing resin and/or carbon.

[Action Co. The present invention will be explained in detail below.

As mentioned in the conventional technology, in the external heating method, the outer layer forms a foam structure with heat insulation properties at the initial stage of foaming, and the structure is such that heat is not easily transmitted to the inside, so thermal efficiency, that is, foaming and curing efficiency, is extremely high. This can lead to a decline in productivity, and foaming starts from the outer layer.
The foam structure has a density distribution in the thickness direction that is low in the outer layer and high in the inner layer, which has the disadvantage of making the phenol foam brittle.

As a means of improving the brittleness of such phenolic foams,
Is there a known idea of reinforcing phenol foam by mixing fibers in it?According to the external heating method, foaming starts from the outside of the foam, so the foaming energy pushes the fibers inside, improving brittleness. The fiber content in the areas near the outside of the foam, where it is most needed for this purpose, is lower, and its effectiveness is significantly reduced. Furthermore, since the adhesion between the fibers and the foam is poor, the actual situation is that no substantial reinforcing effect can be obtained.

On the other hand, with the internal heating method, i.e., the foaming and curing method using high-frequency irradiation, conventionally known methods tend to cause shrinkage and sagging during foaming, resulting in dimensional changes.Furthermore, unevenness may occur on the surface of the foam. High-frequency irradiation has inherent drawbacks such as the fact that the shape of the entire foam tends to become non-uniform due to irradiation spots, and there is also a problem of brittleness, which is not preferable.

Therefore, the present invention solves the disadvantages of fiber reinforcement by filling a foam with fibers using the external heating method, and the disadvantages in foaming and curing using the internal heating method, as well as the drawbacks in terms of the performance of the foam.

That is, the present invention involves mixing or mixing any one or a combination of a. fibers and/or fabrics, b. super absorbent resin, and C. carbon into a phenolic resin composition, and then It foams and hardens by irradiating it with high frequency waves including waves. The present invention is characterized by such a configuration, and for the first time in this configuration, highly efficient foaming, curing, uniform foaming structure, elimination of shrinkage and sagging,
It is possible to provide a method for producing a phenol foam and a phenol foam that satisfies improved brittleness and surface uniformity.

The high frequency processing of the present invention is performed by a waveguide method or an open method using a high frequency irradiation device that generates high frequency waves with a frequency of 106 to 1012 Hz.

In other words, since the present invention is high frequency processing in a broad sense including the frequency range (109 to 1012) generally referred to as microwaves, this will be collectively referred to as high frequency hereinafter.

By placing a phenolic resin formulation containing any one or a combination of a, b, and c above in the electric field generated by such a device, the components contained in the formulation self-heat due to the action of dielectric heating, causing the The foaming agent contained in the compound is vaporized to form a foamed structure, and the phenol resin initial condensate is further polymerized and cured to form a foamed product.

Therefore, the feature of the present invention is that the compound foams and hardens due to self-heating, so unlike the external heating method,
By starting foaming from the surface layer, a heat insulating layer is formed on the surface layer, which solves the problem of difficulty in transmitting heat to the inside, allowing for uniform, rapid and efficient foaming and curing to the inside.

A phenolic resin compound is a compound containing any one or a combination of the above a, bSC, and at least a material constituting a foam, for example,
It refers to a product containing a phenolic resin initial condensate, a curing agent for curing the condensate, a foaming agent for foaming, a foam stabilizer for controlling the cell condition, and the like. In addition, additives such as flame retardants, neutralizers, and colorants may also be included depending on the purpose and use. These formulations include, but are not limited to, all of the additives normally used in the production of phenolic foams.

As the phenol resin in the present invention, novolac type and resol type phenol resin initial condensates are used. Here, the novolak-type phenolic resin initial condensate is a so-called novolak-type phenol resin known in the art, which is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst, and is a hardening agent. In its presence, polymerization can proceed further.

On the other hand, the resol type phenolic resin initial condensate is a so-called resol type phenol resin (including benzylic ether type) known in the art, which is obtained by reacting phenols and aldehydes in the presence of a basic catalyst. Polymerization can usually proceed by heating.

The high frequency applied in the present invention has a frequency of 105 to 10'.
It is between 2■Tz. Although it varies depending on the formulation, foaming and curing can be performed particularly efficiently in 107 to ]081-1z.

The irradiation device is not particularly limited, and various commercially available devices that irradiate high frequency waves can be used. For example, depending on the arrangement of the electrode plates, any high frequency irradiation device can be used, such as a box type, parallel plate type, opposing grid type, one side grid type, and opposing houndstooth type. In addition, methods for molding phenolic resin compounds include hand mixing,
Block foaming method, injection foaming method, continuous lamination method, current
This can be carried out by providing the above-mentioned apparatus in a commonly used molding method for producing phenol foam, such as a field spray method, and incorporating a high-frequency irradiation step.

Further, in the present invention, not only heating using high frequency waves but also other heating means may be used in combination. For example, electric heat, gas,
After preheating with an external heating device using steam,
These methods include high-frequency irradiation, high-frequency irradiation followed by passing through another heating device, and high-frequency irradiation followed by hot pressing and molding, which are preferable in order to reduce foaming and hardening spots.

High-frequency irradiation may be performed continuously or intermittently,
Furthermore, the irradiation output and frequency may be constant or may be varied.

The present invention combines the above-described foaming and curing treatment by high-frequency irradiation with the following means, and can obtain various effects that cannot be obtained by conventional foaming and curing by high-frequency irradiation.

In other words, ■ This is a method in which fibers and/or fabrics are placed inside and/or on the surface of a phenolic resin compound and then irradiated with high frequency to foam and harden, making it possible to extremely effectively reinforce the phenol foam. .

The present invention is completely different from conventionally known fiber reinforcement of foams, in that after fibers and/or fabrics are provided, a phenolic resin compound is irradiated with high frequency to foam and harden the foam, as well as to achieve fiber reinforcement. Although the effect is not always clear,
It is thought that the surface of the fibers is activated, and the major feature is that the adhesive and integration of the fibers and the foam is extremely good, and that a reinforcing effect that cannot be obtained with conventionally known fiber reinforcement is exhibited.

Fibers used for such reinforcement include polyesters, nylons, polyvinyl alcohol, polypropylene, polyethylene, polytan, polyacrylonitrile, polyacrylic acid ester, polystyrene, copolymer modified products, or mixtures of other components. Any known spinnable polymer can be used. Preferably, one or more polymers from these polymer groups are used depending on the use and purpose.

In particular, the components of dielectric early maturing that do not easily generate heat due to high-frequency irradiation (
Composite fibers are preferably used, which are a combination of component A) and a dielectric fast-onset component that easily generates heat (component B). Such composite fibers include core-sheath type fibers, bimetal type fibers, multilayer bonded fibers, radial multilayer type fibers, etc. Among these, core-sheath type fibers using component A in the core and component B in the sheath are preferable.
In particular, polymer array fibers and mixed spun fibers in which a plurality of cores are arranged in a sheath are preferably used. A multicore sheath-type fiber using polyethylene terephthalate as a core and low-melting nylon as a sheath is a particularly preferred combination because the sheath component heats up and melts when exposed to high frequency irradiation, resulting in good adhesion to the foam. In addition, it may be a composite yarn (core-sheath type composite yarn, bimetal type composite yarn, etc.) in which the A component and the B component are mixed or twisted. It is also preferable that a fabric (any one of a woven fabric, a knitted fabric, a nonwoven fabric, a reticulated sheet, or a composite or a mixture thereof) containing such composite fibers is disposed inside and/or on the surface of the foam. Can be reinforced.

(2) By mixing a super absorbent resin in a phenol resin compound and irradiating it with high frequency, the efficiency of foaming/curing can be further increased, and the brittleness and surface uniformity of the phenol foam can be improved.

The superabsorbent resin used in the present invention is also called a polymer absorber, which has a high water absorbency several tens to hundreds of times its own weight. Typical examples include modified starch, cellulose, crosslinked starch/acrylic graft polymers, polyacrylonitrile derivatives, polyacrylamide, polyacrylate, saponified vinyl acetate/methyl acrylate copolymer, and polyacrylic. These are acid salt polyvinyl alcohol polymer crosslinked products, etc., and these are used alone or as a mixture of two or more kinds. Among these, crosslinked starch-acrylic graft polymers and polyacrylates are preferably used.

These superabsorbent resins may be in the form of particles, powder, film, or lumps, and the particle size and size are not particularly limited, but it is preferable to use them in a state with a large surface area.

The content ratio of the super absorbent resin in the foam is not particularly limited, but the super absorbent resin is usually mixed in 0.1 to 50 parts by weight per 100 parts by weight of the foam structure. is preferred, and it is particularly preferred that 1 to 20 parts by weight be further mixed.

(2) By mixing carbon in the phenol resin compound and applying high frequency irradiation, the efficiency of foaming and curing can be further increased, and furthermore, the brittleness of the phenol foam can be significantly improved.

Furthermore, conductive properties can also be imparted to the phenol foam.

Such carbons include carbon black, activated carbon, porous carbon, carbon fiber, carbate, graphite, etc. Among these, porous carbon and activated carbon have the property of being well integrated with the phenol foam, so they are less brittle. It is a preferred additive as it can significantly improve the

As described above, the present invention can obtain unprecedented effects by using any one or a combination of the above a, b, and c. The combinations of a, b, and c may be all or any combination depending on the use and purpose of the phenol foam.

The phenol foam produced by the production method of the present invention can be used in metal sizing, wall panels, ceiling panels, housing materials such as underground insulation materials, chemical plants, LPG, LNG tanks, heavy oil/crude oil tanks, various types of insulation covers, and other plant industrial fields. ,
It can be preferably used in the field of ships and vehicles such as refrigerated ships, refrigerated vehicles, marine containers, and automobile ceiling materials, and in the field of insulation equipment such as showcases, stockers, and vending machines.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the validity and scope of the rights of the present invention are not limited or restricted by these Examples. Rather, it brings about the next application and development.

In addition, in the examples, all "proportions" are based on weight.

Example 1 A phenol foam was molded using the following phenol formulation and high frequency equipment.

■Resol type phenol resin for foaming phenolic compound 100 parts Foam stabilizer: Nonionic activator 1 part Foaming agent: Freon 113
10 parts Hardening agent: Organic sulfonic acid
15 parts Super absorbent resin: polyacrylate system 10 parts Reinforcement fiber: 5 mm fiber length polyester (core) / low melting point nylon (sheath) core-sheath composite fiber 10 parts ■High frequency device frequency: 2450 MHz output / 10 KW electrode plate Arrangement: Opposed houndstooth type conveyor: Polyfluoroethylene fiber Irradiation time: 5 minutes After stirring and mixing the phenol compound, it is extruded into a sheet using an extruder with a slit-shaped nozzle, and foamed through a high-frequency device. , hardened.

As a result, this foaming and curing process can be performed faster than conventional processing methods, and the resulting foam also has better mechanical performance than conventional phenol foams. It was in good condition and was easy to construct as a residential construction panel because the surface and edges were not chipped.

Example 2 A phenol foam was molded using the following phenol formulation and high frequency equipment.

■Novolac type phenol resin for foaming phenolic compound 100 parts Foam stabilizer
Silicone-based 2 parts Foaming agent, dinitrosopentamethylene 10 parts Tetramine Hardening agent Hexamethylenetetramine 15 parts Reinforcement fiber: core-sheath composite fiber of polypropylene (core) with a fiber length of 10 mm/low melting point nylon (sheath) 10 parts super absorbent resin : Starch/acrylic 10 parts Graft polymer crosslinked carbon: Activated carbon 10 parts High frequency device frequency: 27.12 MHz Output 28 KW (effective output 15 KW) Arrangement of electrode plates Two opposing houndstooth type conveyor: Polyfluorinated ethylene fiber Irradiation time: 5 minutes After the phenol mixture was stirred and mixed, it was placed in a polypropylene container, and foamed and cured through a high-frequency device. As a result, this foaming and hardening process can be performed faster than conventional processing methods, and furthermore,
The obtained foam had excellent shape retention compared to conventional phenol foam, and was suitable as a heat insulating material for residential construction and the like.

[Effects of the Invention] The present invention provides high frequency treatment of a phenolic resin compound containing any one or a combination of the following: (a) fibers and/or fabrics, (b) super absorbent resins, and (C) carbons. It is irradiated to foam and harden to form a phenol foam.

According to the present invention, the brittleness of the foam can be significantly improved compared to the conventional method of manufacturing phenol foam using external heating method for fiber reinforcement or simple high-frequency irradiation. It is capable of high foaming and curing, and has effects such as creating a uniform foam structure, eliminating shrinkage and sagging, and improving surface uniformity.

Claims (1)

[Scope of Claims] (1) A phenol characterized by arranging fibers and/or fabric inside and/or on the surface of a phenol resin compound, and then irradiating the phenol resin with high frequency to foam and harden the phenol resin. Method of manufacturing foam. (2) The method for producing a phenol foam according to claim 1, wherein the fiber and/or fabric comprises a composite fiber composed of two or more composite components having different dielectric constants. (3) The phenolic foam according to claim 2, wherein the composite fiber is a core-sheath type composite fiber, and the dielectric constant of the core component is smaller than the dielectric constant of the sheath component. Production method. (4) A method for producing a phenol foam, which comprises mixing a super absorbent resin in a phenol resin compound, and then irradiating the phenol resin with high frequency to foam and harden the phenol resin. (5) A method for producing a phenol foam, which comprises mixing carbon into a phenol resin compound, and then irradiating the phenol resin with high frequency waves to foam and harden the phenol resin. (6) After arranging fibers and/or cloth inside and/or on the surface of the phenolic resin compound and mixing superabsorbent resin and/or carbon, the phenolic resin is foamed by irradiation with high frequency. A method for producing a phenol foam, characterized by curing it. (7) A phenol foam foamed and cured by high-frequency irradiation, characterized in that the interior and/or surface of the foam is reinforced with fibers and/or fabrics. (8) The phenol foam according to claim 7, wherein the fiber and/or fabric comprises a composite fiber made of two or more composite components having different dielectric constants. (9) The phenolic foam according to claim 8, wherein the composite fiber is a core-sheath type composite fiber, and the dielectric constant of the core component is smaller than the dielectric constant of the sheath component. (10) A phenol foam foamed and cured by high-frequency irradiation, characterized in that a superabsorbent resin is mixed in the foam. (11) A phenol foam foamed and cured by high-frequency irradiation, characterized in that carbon is mixed in the foam. (12) A phenolic foam foamed and cured by high-frequency irradiation, the interior and/or surface of the foam is reinforced with fibers and/or fabric, and the foam contains a superabsorbent resin and A phenol foam characterized by containing/or carbon.