JPH0542974B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial application field This invention relates to a highly expanded phenolic resin foam and a method for producing the same. More specifically, the present invention relates to a highly expanded phenolic resin foam useful as a heat insulating material such as a building heat insulating material, a sound insulating material, and a shock absorbing material, and a method for producing the same. (B) Prior Art Phenol resin foams are useful as various building materials because they have heat insulating properties, cushioning properties, and are themselves flame retardant. Such phenolic resin foams are usually produced by mixing a novolac type or resol type phenolic resin initial condensate with an appropriate amount of an inorganic or organic decomposition type blowing agent and, if necessary, a curing agent, and then placing this mixture in a mold of a predetermined shape. This is done by filling the foam and heating it to a temperature higher than the foam curing temperature. And usually, foam curing consists of resin softening (50~90℃), blowing agent decomposition (90~120℃), and resin hardening (130~120℃).
It is carried out through a process of 150℃). (C) Problems to be Solved by the Invention However, in the above conventional method, even if the amount of the decomposable blowing agent added is increased or the molecular weight of the initial condensate and the foam curing conditions are variously adapted, It was only possible to obtain a foam with an expansion ratio of about 60 times. This invention was made in view of these problems and in response to the ever-desired demand for highly foamed materials to reduce the weight of foamed materials. It is an object of the present invention to provide a manufacturing method that can easily manufacture foams. (d) Means for Solving the Problems Thus, according to the present invention, a foamable phenolic resin composition comprising an initial condensate of phenolic resin, a decomposition type blowing agent, and a curing agent added as necessary, Curing of the foamable phenolic resin composition at a temperature equal to or higher than the softening temperature of (a) 0.5 to 20 parts by weight of a surfactant and (b) 1 to 30 parts by weight of the above phenolic resin initial condensate per 100 parts by weight of the condensate. This composition is filled into a mold of a desired shape and heated to a temperature higher than the foam curing temperature to reduce the average cell diameter.
A method for producing a highly expanded phenolic resin foam is provided, which is characterized by obtaining a phenolic resin foam of 0.1 to 0.9 mm and an expansion ratio of 70 to 200 times. The most distinctive feature of this invention is that when heating and foaming a foamable phenolic resin composition containing a phenolic resin initial condensate, a surfactant and a specific solvent such as water or alcohol are added to the composition in a specific amount. By allowing it to exist, a significantly highly foamed phenolic resin molded article can be provided. In particular, the above fact can be said to be surprising since conventionally, in the foaming of phenolic resins, it is preferable to avoid water and the like as much as possible during molding, and the foam molding is usually carried out after drying. (Expansible Phenol Resin Composition) Examples of the phenolic resin initial condensate in the present invention include novolac-type and resol-type phenolic resin initial condensates. Here, the novolak type phenolic resin initial condensate is a so-called novolak type phenolic resin known in the art, which is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst, and is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst. It means that polymerization can proceed further. This resin is generally in powder form at room temperature. On the other hand, the resol type phenolic resin initial condensate is a so-called resol type phenolic resin known in the art, which is obtained by reacting phenols and excess aldehydes in the presence of a basic catalyst, and is usually heated. means that polymerization can proceed. Among these, it is preferable to use a powdered resol type phenolic resin. The above phenols include, in addition to phenol,
3,5-xylenol, m-cresol, 2,5
-xylenol, 3,4-xylenol, 2,4
-xylenol, 0-cresol, p-cresol, etc. Further, aldehydes include formaldehyde, paraformaldehyde, hexamethylenetetramine, furfural, acetaldehyde, acetals, and the like. A preferred precondensate for use in this invention is a condensate of phenol and formaldehyde. In the present invention, the decomposable blowing agent refers to inorganic and organic blowing agents that can decompose and generate gas during heat curing in a composition mixed with the above-mentioned phenolic resin initial condensate. Typical examples of these are:
N,N'-dinitrosopentamethylenetetramine,
Organic decomposition type blowing agents such as benzenesulfonyl hydrazide, azobisisobutyronitrile, azodicarbonamide, paratoluenesulfonyl hydrazide, as well as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonium sulfite,
Examples include inorganic decomposition type blowing agents such as azide compounds (eg CaN ₆ ). All of these are in powder form. The amount of the blowing agent to be added is the required amount, mainly taking into consideration the density of the desired final foam, but it is 1 to 50 parts by weight per 100 parts by weight of the phenolic resin initial condensate. ~100 parts by weight is preferred. Hardeners are used in particular when novolak-type phenolic resin precondensates are used. This curing agent means a compound that can be decomposed by heating and can undergo a crosslinking reaction with the novolak type phenolic resin initial condensate.
Such compounds include, like formaldehyde, compounds that are used to form phenolic resins by reaction with phenols, and are usually in powder form. Specific examples include hexamethylenetetramine, paraformaldehyde, methylal, dioxolane, trioxane, tetraoxane, trimethylolphosphine, S-triazine, and the like. The amount of the curing agent added is generally 1 to 30 parts by weight, preferably 4 to 15 parts by weight, per 100 parts by weight of the novolak type phenolic resin initial condensate. The foamable phenolic resin composition in this invention usually includes the above-mentioned phenolic resin initial condensate,
The decomposable foaming agent and the hardening agent added as necessary are kneaded using a heating roll or the like at a temperature below the foaming curing temperature, mixed uniformly, and pulverized to be used in the form of a powder with an outer diameter of 1 mm or less. Of course, granules may also be used. It may also be temporarily lumpy. In addition, additional additives such as fillers may be mixed in the resin composition, examples of which include inorganic powdered substances such as clay, talc, borax, zinc oxide, and calcium carbonate; Examples include fluorine-based and silicon-based organic polymer powders. (Surfactant) A surfactant that acts as a foam stabilizer or foam regulator. As such a surfactant, various known surfactants can be used. Specific examples of such surfactants include nonionic surfactants such as alcohols, alkylphenols, fatty acids, alkylsilane polysiloxanes, etc. to which polyalkylene oxide (especially polyethylene oxide) is added (for example, polyoxyalkylene alkyl ether polysilicon). oxyalkylene alkyl phenol ether,
Fatty acid alkylene oxide adducts, polyoxyalkylene fatty acid esters, alkylsilane alkylene oxide adducts, polyorganosiloxane alkylene oxide adducts, polyoxyethylene/
polyoxypropylene copolymers, etc.), nonionic surfactants such as fatty acid esters of polyhydric alcohols (e.g. sorbitan monolaurate, sorbitan monopalmitate, etc.), cationic surfactants of the quaternary ammonium salt type ( For example, cetyldimethylpenzylammonium chloride, octadecyldimethylbenzylammonium chloride,
octadecanol-9-dimethylethylammonium bromide, diisobutylphenoxyethyldimethylbenzylammonium chloride, etc.). Among these, silicone type surfactants are particularly suitable, dimethylpolysiloxane surfactants are preferred, and dimethylpolysiloxane-polyoxyalkylene copolymers are particularly preferred. The amount of surfactant used may vary depending on the type of surfactant, but it is usually about 0.5 to 20 parts by weight per 100 parts by weight of the phenolic resin initial condensate.
The amount is preferably 0.5 to 5 parts by weight. If these amounts are too large, the foam may collapse during molding, so it is not suitable. (Solvent) A solvent having a boiling point within a temperature range that is higher than the softening temperature of the phenolic resin initial condensate and lower than the curing temperature of the foamable phenolic resin composition is used. Those outside this range are not useful for high foaming because they volatilize before the condensate is softened or volatilize after curing. However, if the softening temperature of the phenolic resin initial condensate is lowered by the solvent, a solvent whose boiling point is lower than the resin softening temperature can also be used. Note that the boiling point here means the boiling point at the time of thermoforming, and although there is some variation, it is generally almost the same as the normal pressure boiling point, so it is sufficient to judge based on the normal pressure boiling point. Generally, the softening temperature of the above condensate is about 50-90℃,
Since the curing temperature is approximately 130 to 150°C, the solvent usually selected has a normal pressure boiling point of approximately 50 to 150°C.
A temperature of about 90 to 130°C is preferred. As these solvents, not only hydrophilic ones but also lipophilic ones can be used, but hydrophilic ones are usually suitable, and examples include water and hydrophilic solvents. Acetone, methanol, ethanol, etc. are suitable as hydrophilic solvents. These may be a mixture. These solvents are contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the phenolic resin initial condensate in the foamable phenolic resin composition. If the amount is less than 1 part by weight, high foaming cannot be achieved, and if it exceeds 30 parts by weight, foam breakage will be significant and the molded product will not be able to hold its shape, which is inappropriate. Among these, the content of the solvent is usually preferably 3 to 20 parts by weight, particularly 100 parts by weight.
In order to obtain a highly foamed product more than double the amount, the amount is preferably 5 to 20 parts by weight. The composition of these solvents and the activator is as follows:
Although it depends on the form of the foamable phenolic resin composition, it is usually suitable to use a powder or granule as the resin composition and directly add and mix the resin composition. However, this may be carried out by immersing the lumps of the resin composition before granulation into the above-mentioned solvent, or it may be added at the time of mixing and adjusting the resin composition. (Molding) The highly foamable phenolic resin foam of the present invention can be obtained by filling the foamable phenolic resin composition containing the above solvent and surfactant into a mold of a desired shape and heating it above the foaming curing temperature. The heating at this time is usually suitably carried out at a temperature of about 130 to 200°C. Further, it is usually preferable that the above-mentioned composition is filled into a mold in the form of powder or granules when the amount of solvent contained is low, but in some cases it may be filled in the form of pellets or fragments. When the amount of solvent contained is large, it is used in a viscous or paste form. The filling factor is adjusted according to the intended expansion ratio and should be at least 70
It is set to obtain a magnification of 2 times or more. The mold used is one equipped with a gas vent hole, and it is suitable to use one that can be divided into upper and lower or left and right parts.
The intermediate material that expands during molding is subject to pressure because it is closed in a mold, but it is appropriate to set this pressure to be lower than before, and usually
Approximately 0.5 to 2.0 kgf/ ^cm2 is suitable. In addition, it is preferable to set a release paper inside the mold, especially at the bottom or the top, because it makes it easier to release the mold after foaming. By using a decorative board made of wood, synthetic resin, etc., or a film material made of synthetic resin, synthetic fiber, etc.), the present foamed molded article having the surface material on the surface can be easily obtained. The foam thus obtained has an average cell diameter of
Although the foam size is 0.1 to 0.9 mm, the foaming ratio is 70 to 200 times, which is a high foaming ratio, and the shape is good enough to maintain its shape. Therefore, due to its high expansion ratio, its thermal conductivity is extremely low. Such foams are novel in themselves and are useful for applications such as building materials. Therefore, the present invention also provides a highly foamed phenolic resin body in which the base resin is made of a phenolic resin, the average cell diameter is 0.1 to 0.9 mm, and the expansion ratio is 70 to 200 times. Of course, this foam itself may have a surface material on its surface. (e) Effect In this invention, although it is not clear how well a highly foamed product can be obtained, it is not only the curing that acts as a blowing agent itself, but also the foaming effect of the decomposable blowing agent in which the solvent is used to increase its volatility. An auxiliary action based on the action, an action that suppresses the rapid rise in resin temperature to the curing temperature due to the heat of vaporization of the solvent, an action that preferentially advances foaming, an action that prevents local heating, and a plasticizer for the initial resin condensate. This is thought to be based on the chemical effect and the effect that bubbles are adjusted by the surfactant. (f) Examples Example 1 [a] Uncured novolac type phenol-formaldehyde resin 100 parts by weight [b] Hexamethylenetetramine (curing agent)
8 parts by weight [c] Dinitrosopentamethylenetetramine (foaming agent) 10 parts by weight The uncured phenolic resin in [a] above is
It has an ortho-para random structure, an average molecular weight of 530, and a free phenol content of about 2%. Further, 5 parts by weight of a silicone-type surfactant (dimethylpolysiloxane-polyoxyalkylene copolymer, trade name SH-193 manufactured by Toray Silicone Co., Ltd.) was added to the above [a], [b], and [c], and mixed by roll. The mixture was kneaded in a machine at 80° C. for about 5 minutes, cooled, and pulverized to prepare 100 mesh passes of foamable phenolic resin powder. This foamable phenolic resin composition has a melting point of 76°C and a gelation time of 150 seconds at 150°C.
The flowability was 270 seconds at 130°C and 49 mm at 125°C. Next, add 25 g of water to 100 g of this foamable resin composition.
and mixed for 5 minutes at about 50°C. The moisture content of the foamable resin mixture thus obtained was measured by drying it in a desiccator for 96 hours using silica gel as a drying agent according to the method of JIS-K6910. for
The water content was 19.42g). This water-containing mixture was in the form of yellowish clay and had plasticity (fluidity) at temperatures above about 30°C. Next, the dimensions inside the mold are height 25mm, width 250mm x 250
After placing a release paper on the bottom of a mold with a flat bottom and an openable lid, 17.5g of the crushed foamed resin mixture was placed, and release paper was placed on the top of the mold. , the lid was closed, and press heating was performed for 30 minutes at a heating temperature of 150° C. and a molding pressure of 2 kg/cm ² . The obtained phenol foam was a yellowish foam having a uniform, fine cell structure with an average cell diameter of 0.3 mm in which the entire mold was uniformly filled with phenol foam. The density of this phenol form is 9
It was a phenol foam with a high expansion ratio of 150 times (phenolic resin true specific gravity: 1.35) at Kg/m ³ . The physical properties of this molded body are shown in the table below.

【table】

[Table] Example 2 20 g of acetone (special grade reagent) was added to 100 g of the same foamable phenolic resin composition powder used in Example 1, and mixed for 5 minutes at room temperature to prepare a foamable resin mixture. This mixture of acetone and foamable resin was a viscous substance that had fluidity even at room temperature. Next, 10 g of the above foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol form has a diameter of 0.4 m/mφ
It was a brownish, highly foamed material with an average cell diameter of , and exhibited the highest foaming ratio in the free state. The density of this phenol form is 15.7
Kg/m ³ and the foaming ratio was 86 times. Example 3 Add methyl alcohol (special grade reagent) to 100 g of the same foamable phenolic resin composition powder used in Example 1.
20g was added and mixed for 5 minutes at room temperature to prepare a foamable resin mixture. This mixture of methyl alcohol and foamable resin was a viscous substance that had fluidity even at room temperature. Next, 10 g of the above foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol form has a diameter of 0.7m/mφ
It was a yellowish, highly foamed material with an average cell diameter of , and exhibited the highest foaming ratio in the free state. The density of this phenol form is 10.0
Kg/m ³ and the foaming ratio was 135 times. Example 4 Ethyl alcohol (special grade reagent) was added to 100 g of the same foamable phenolic resin composition powder used in Example 1.
20g was added and mixed for 5 minutes at room temperature to prepare a foamable resin mixture. This mixture of ethyl alcohol and foamable resin was a viscous substance that had fluidity even at room temperature. Next, 10 g of the above foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol form has a diameter of 0.7m/mφ
It was a yellowish, highly foamed material with an average cell diameter of , and exhibited the highest foaming ratio in the free state. The density of this phenol form is 13.3
Kg/m ³ and the foaming ratio was 102 times. Example 5 Ethyl alcohol (special grade reagent) was added to 100 g of the same foamable phenolic resin composition powder used in Example 1.
4 g and 16 g of xylene (special grade reagent) were added and mixed for 5 minutes at room temperature to prepare a foamable resin mixture. This mixture of ethyl alcohol, xylene, and foamable resin had clay-like plasticity at room temperature. Next, 10 g of the above foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol form is 0.8m/mφ
It was a yellowish, highly foamed material with an average cell diameter of , and exhibited the highest foaming ratio in the free state. The density of this phenol form is 18.0
Kg/m ³ and the foaming ratio was 75 times. Example 6 A mixture of the same water-containing foamable resin composition as used in Example 1 (moisture content: 16.42 wt%) was used, and the pulverized mixture was heated in a hot air circulation thermostat with an internal air velocity of 3 m/sec. Dry, foamable resin compositions with different water contents were prepared. In addition, the drying conditions and the water content of the obtained foamable resin composition are shown in the table below.

【table】

[Table] Next, 10 g of the above water-containing composition powder was placed in the same mold as in Example 1, and press-heated under the same molding conditions. The obtained phenol foams were all yellowish and highly foamed with a fine cell structure, and exhibited the highest expansion ratio in the free state. The weight and volume of this molded product, the density of the phenol foam, and the expansion ratio are shown in the table below and FIG. 1.

[Table] Example 7 [a] Uncured novolak type phenol-formaldehyde resin (ortho and para random structure type, average molecular weight 540, free phenol 2%) [B] Uncured novolak type phenol-formaldehyde resin (high ortho structure) Type, average molecular weight
500, free phenol 2%) [c] Hexamethylenetetramine (hardening agent) [d] dinitrosopentamethylenetetramine (foaming agent) The above [a], [b], [c], and [d] in the mixing ratios shown in the table below. Dry blend and add a silicone type surfactant (dimethylpolysiloxane-polyoxyalkylene copolymer, trade name manufactured by Toray Silicone Co., Ltd.)
5 parts by weight of SH-193) were added to prepare a foamable resin composition.

[Table] These foamable resin compositions were prepared into a water-containing mixture in the same manner as in Example 1. The water content at this time was in the range of 16.1 to 16.7 wt%. Next, a pulverized product of this water-containing foamable resin composition mixture
10 g was pressed and heated in the same mold as in Example 1 under the same molding conditions. The obtained phenol foams were all yellowish foams with a fine cell structure and a high expansion ratio, and exhibited the highest expansion ratio in a free state. The density and expansion ratio of these phenol foam molded bodies are shown in the table below.

【table】

[Table] Example 8 A foamable phenolic resin composition powder was prepared using the same raw materials, formulation, and formulation as in Example 1 except that it did not contain a silicone type surfactant. 100 g of this foamable phenolic resin composition, 5 g of an organic surfactant (propylene glycol added to polypropylene glycol, trade name Pronon 208, manufactured by NOF Corporation) and methyl alcohol.
A foamable resin mixture was prepared by spraying 25 g of the mixture and mixing at room temperature for about 5 minutes. Next, 10 g of the above foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol foam is a yellowish highly foamed material with an average cell diameter of 0.9 mmφ.
It showed the highest foaming ratio in the free state. The density of this phenol form is 18.0
Kg/m ³ and the foaming ratio was 75 times. Example 9 A foamable phenolic resin composition powder was prepared using the same raw materials, blending, and prescription as in Example 1 except that the silicone type surfactant was not included. A silicone type surfactant and a solvent were mixed with 100 g of this foamable phenolic resin composition at the blending ratio shown in the table below to prepare a foamable resin mixture.

[Table] Next, 10 g of the foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol foams were all yellowish foams with a high expansion ratio, and exhibited the highest expansion ratio in a free state. The density, expansion ratio, and average cell diameter of these phenol foam molded products are shown in the table below.

[Table] Example 10 [A] Uncured resol type phenol-formaldehyde resin 100 parts by weight [B] Dinitrosopentamethylenetetramine (foaming agent) 10 parts by weight The above [A] and [B] were heated at 80°C in a roll mixer.
The mixture was kneaded for about 5 minutes, cooled, and then ground to obtain a powdered foamable resin composition. This foamable resin composition
The melting point was 75°C after 100 mesh passes. Add a silicone type surfactant (dimethylpolysiloxane) to 100g of this foamable phenolic resin composition.
3 g of polyoxyalkylene copolymer (manufactured by Toray Silicone Co., Ltd., trade name SF2933) and 20 g of water were sprinkled and mixed at about 50° C. for 5 minutes to prepare a foamable resin mixture. This water-containing mixture had a reddish-brown clay-like form and was plastic at temperatures above about 30°C. Next, 10 g of the pulverized foamable resin mixture was placed in the same mold as in Example 1, and press heating was performed under the same molding conditions as in Example 1. The obtained phenol foam was a yellowish, highly foamed material having a uniform, fine cell structure with an average cell diameter of 0.3 mmφ, and exhibited the highest expansion ratio in the free state. The density of this phenol foam was 10.3 Kg/m ³ and the expansion ratio was 131 times. Comparative Example Using the same five types of foamable phenolic resin compositions as used in Example 7, press heating was performed using the same mold, resin amount, and molding conditions as in Example 7 without mixing with water. The obtained phenol foam was a foam having a dense cell structure and exhibited the highest expansion ratio in a free state, but the phenol foam density was about 25 to 40 kg/m ³ . The densities and expansion ratios of these phenol foams are shown in the table below and in FIGS. 2 and 3.

[Table] (G) Effects of the Invention According to the present invention, an extremely highly foamed phenolic resin foam, which has been difficult to produce in the past, can be easily obtained. It also has good moldability, so it can be formed into any shape by selecting the mold.For example, it can be made into a plate shape for use as a heat insulating board for construction, or a cylindrical shape as a heat insulating material for covering pipes. is also possible.

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the relationship between solvent content and foam density in Examples of the present invention, and FIGS. 2 and 3 are graphs illustrating the foam densities of Examples together with Comparative Examples.

Claims (1)

[Scope of Claims] 1. A foamable phenolic resin composition consisting of a powdered phenolic resin initial condensate, a decomposable foaming agent, and a curing agent added as necessary, is added to (1) per 100 parts by weight of the phenolic resin initial condensate. a) 0.5 to 20 parts by weight of a surfactant and (b) 1 to 30 parts by weight of a boiling point within a temperature range that is above the softening temperature of the above phenolic resin initial condensate and below the curing temperature of the above foamable phenolic resin composition. This composition is filled into a mold of a desired shape, heated to a temperature higher than the foam curing temperature, and the average cell diameter is
A method for producing a highly expanded phenolic resin foam, characterized by obtaining a phenolic resin foam of 0.1 to 0.9 mm and an expansion ratio of 70 to 200 times. 2. The manufacturing method according to claim 1, wherein the surfactant is a silicone type surfactant. 3. Claim 2 in which the silicone type surfactant is a dimethylpolysiloxane type surfactant.
Manufacturing method described in section. 4. The manufacturing method according to claim 2, wherein the silicone type surfactant is a dimethylpolysiloxane-polyoxyalkylene copolymer. 5. The manufacturing method according to claim 1, wherein the solvent has a normal pressure boiling point of about 50 to 150°C. 6. The manufacturing method according to claim 5, wherein the solvent is water or a hydrophilic organic solvent. 7. The production method according to claim 6, wherein the hydrophilic organic solvent is acetone, methanol, or ethanol. 8. The manufacturing method according to claim 1, wherein the solvent is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the phenolic resin initial condensate.