JPS61233526A - Preparation of composite phenol resin expanded molded product - Google Patents

Abstract

PURPOSE:To obtain a molded body having a composite expanded layer in which fiber and phenol resin expanded layers are mixed, by heating an expandable composite to the expanding and curing temp. of a resin composition or more in a mold. CONSTITUTION:A powdery resin composition 1 is scattered on a fluffy sheet material 2 impregnated with a liquid substance and the same impregnated fluffy sheet material 2 is laminated onto the scattered powder 1 to hold said powder between both sheet materials. Heat treatment is applied at temp. less than the expanding and curing temp. of the resin composition not only to fill the fluffy sheet materials with the resin composition 1' but also voltatilize the liquid substance and the plate shaped expandable composite is subjected to expansion molding in a mold to perform the formation of expanded layers 3 and the expansion of the fluffy sheet materials in the thickness direction. By this manufacturing method, a composite phenol resin expanded molded body having a composite expanded layer, in which fibers and the phenol resin expanded layers are uniformly mixed, can be obtained with good efficiency.

Description

Detailed Description of the Invention (a) Purpose of the Invention (Field of Industrial Application) This invention relates to a method for producing a composite phenolic resin foam molded article. The present invention relates to a method for producing a composite phenolic resin foam molded product, which has a composite foam layer containing a mixture of phenolic resins and is useful as various cushioning materials, heat insulating materials, exterior panels, and partition boards.

[Prior art]

Conventionally, in order to improve the mechanical strength of phenolic resin foam moldings, it has been considered to mix various reinforcing fiber materials into the phenolic resin foam, and shredded glass fibers, phenol, and resin initial materials have been considered. A method of mixing a foamable resin composition powder containing a condensate (a raw material for phenolic resin foam) and foaming and curing it in a mold, and a cotton-like sheet material in which a large number of powdered foamable resin compositions are laminated. After spreading and sandwiching them between the sheets, the resin composition is preformed using a hot roll or hot press at a temperature that allows the resin composition and the phenol resin initial condensate to melt, and the resin composition is applied inside each cotton-like sheet. A method is known in which the multilayer body is impregnated and held, and then heated to foam and harden the multilayer body (see Japanese Patent Publication No. 8945/1989).

(Problems to be Solved by the Invention) However, in the former method, it is difficult to mix III and the resin composition uniformly, and it is difficult to obtain a foam molded product in which the phenolic resin foam layer and fibers are uniformly mixed. In the latter method, the resin is melted at as low a temperature as possible without causing foaming or curing, and is impregnated into the cotton-like sheet material. However, because the viscosity of the molten resin is high, Even when the sheet is clamped, it is difficult to uniformly impregnate these resins into the sheet, and high pressure (10 to 201 g/ad) is required.
), which requires press processing to roughly improve melt moisture and foaming.
Due to the narrow range from the curing temperature, some foaming and
It may harden, requiring strict heat control, and it has been difficult to easily obtain the intended composite molded product.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a method for easily manufacturing a composite foam molded article in which fibers and a phenol resin foam layer are uniformly mixed.

As a result of extensive research, the present inventors found that when sandwiching the foamable phenolic resin composition powder between the cotton-like sheet materials, a liquid substance compatible with the phenolic resin initial condensate was added to the sheet materials. By impregnating it, at most 1
The resin composition can be uniformly impregnated into the inside of the cotton-like sheet material by a lamination pressure of around kMcd and by low-temperature heat treatment below the melting temperature of the resin composition, and by using a volatile liquid substance, the above-mentioned heating can be carried out. The present invention was achieved by discovering the fact that these substances are substantially removed during processing and that no adverse effects of the liquid substances occur during foam molding.

(B) Structure of the Invention Thus, according to the present invention, a powdered resin composition consisting of a phenolic resin initial condensate, a decomposable blowing agent, and a curing agent added as necessary is prepared in advance with the phenolic resin initial condensate. The above resin composition is sandwiched between a plurality of cotton sheet materials impregnated with a compatible and volatile liquid substance and/or between a cotton sheet material impregnated with the liquid substance and a predetermined face material. By heat-treating at a temperature lower than the melting temperature of the cotton-like sheet material, the resin composition is uniformly impregnated inside the cotton-like sheet material, and each cotton-like sheet material and/or the cotton-like sheet material and the face material are integrated. A composite foam layer containing a mixture of IIAN and a phenolic resin foam layer is obtained by heating the foam composite in a mold to a temperature higher than the foaming/curing temperature of the resin composition. Provided is a method for producing a composite phenolic resin foam molded article, which is characterized by obtaining a molded article having the following.

The most distinctive feature of this invention is that the cotton-like sheet material is pre-impregnated with a volatile liquid substance that is compatible with the resin. As a result, the resin composition softens even at a concentration below its melting temperature and permeates the entire cotton-like sheet material impregnated with the liquid substance, resulting in a composite structure in which the resin composition is uniformly impregnated inside the cotton-like sheet material. By using this, the intended composite phenol resin foam molded product can be easily obtained.

The phenolic resin initial condensate used in this invention includes:
Examples include novolac type and resol type phenolic resin initial condensates. 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. This means that the 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 acid-cured. This means that polymerization can proceed with a chemical agent and heating.

Such a resol type phenolic resin itself is a liquid containing about 20% of reaction water, but it is further dehydrated (evaporated to remove water) to form a solid (containing about 1% of water). Next, this solid material is pulverized to obtain a powdered resol type phenol resin used in the present invention. Of course, a commercially available powdered resol type phenol resin may also be used.

In addition to phenol, the above phenols include 3,5-xylenol, ■-cresol, 2,5-xylenol,
Includes 3.4-xylenol, 2.4-xylenol, 0-cresol, p-cresol, and the like. Also, aldehydes include formaldehyde, paraformaldehyde,
Includes hexamethylenetetramine, furfural, acetaldehyde, acetals, etc. A preferred precondensate for use in this invention is a condensate of phenol and formaldehyde.

The decomposable blowing agent in the present invention refers to inorganic and organic blowing agents that can decompose and generate gas during heat curing in a composition mixed with a phenolic resin initial condensate. A typical example of these is N.

N'-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, azobisisobutyronitrile,
Examples include organic decomposable blowing agents such as azodicarbonamide and paratoluenesulfonyl hydrazide, as well as inorganic decomposable blowing agents such as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonium nitrite, and azide compounds (eg, Ca Ns ). All of these are in powder form.

The amount of the blowing agent to be added is determined based on the desired density of the final foam, but the appropriate amount is 1 to 50 parts by weight per 100 parts by weight of the phenolic resin initial condensate. ~15 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 decomposes when heated and undergoes a crosslinking reaction with the novolac type phenol resin initial condensate.

Such a compound is, like formaldehyde, a compound used to form a phenol resin through a reaction with phenols, and is usually in powder form.

Specific examples include hexamethylenetetramine, paraformaldehyde, methylal, dioxolane, trioxane, tetraoxane, trimethylolphosphine,
Examples include s-triazine.

The amount of curing agent added is generally 1 to 30 parts by weight per 100 parts by weight of novolac type phenolic resin, and 4 parts by weight.
~15 parts by weight is preferred.

The powdered resin composition of the present invention is usually prepared by kneading the above-mentioned phenolic resin initial condensate, a decomposable blowing agent, and, if necessary, a curing agent, using a heated roll or the like to uniformly mix the mixture, and then crushing it. It is used in powder form with a diameter of 1 mm or less. Of course, granules may also be used.

The foamable resin composition of the present invention may also contain small amounts of other various additives, such as fillers such as clay and talc. The amount of these additives is preferably 100 parts by weight or less per 10 parts by weight of the novolac type or resol type phenolic resin.

Examples of the cotton-like sheet material used in this invention include organic nonwoven fabrics such as cotton, recycled fibers, and synthetic fibers, and inorganic nonwoven fabrics such as glass fibers, metal fibers, and carbon fibers, and those having a thickness of 20 μm to i omm are suitable. The basis weight is 20~
1000g4 is suitable. In this invention, two cotton-like sheet materials are usually used, and the resin composition may be sandwiched between them, but in some cases, multiple layers may be laminated and the resin composition is sandwiched between each layer. Alternatively, it may be constructed by laminating a cotton-like sheet material and a face material. Examples of the surface material used in this case include organic plate-like materials such as plywood and hardboard, metal plates such as stainless steel, aluminum, iron, and galvanized iron, and inorganic plate-like materials such as asbestos cloth and gypsum board.

The liquid substance with which the cotton-like sheet material is impregnated in advance is a volatile liquid substance that is compatible with the phenolic resin initial condensate and easily dissipates at a temperature below the melting point of the resin composition. used.

Preferred examples include lower alcohols such as methanol and ethanol, aromatic solvents such as benzene, toluene, and xylene, acetone, and water; Any liquid material that can dissolve the resin precondensate can be used.

The amount of the liquid substance impregnated varies depending on the thickness and basis weight of the cotton-like sheet material and the amount of resin composition applied, but usually 5 to 2 parts per sheet material per 100 parts by weight of the resin composition to be interposed.
It is sufficient to impregnate it with 00 parts by weight of a liquid substance, and 15~
The amount is preferably 50 parts by weight. Impregnation may be carried out by coating or dipping when the amount of liquid substance is large.
Generally, it is preferable to use a spray method from the viewpoint of uniformity of impregnation.

A predetermined amount of the resin composition powder is sprinkled or placed between cotton-like sheet materials impregnated with a liquid substance or between this cotton-like sheet material and a predetermined surface material, and these are applied to the cotton-like sheet material or surface material. A plate-shaped foamable composite material, which is the foaming material of the present invention, can be obtained by heat-treating the composite material while being sandwiched between the two materials. At this time, it is sufficient to hold each cotton-like sheet material or face material to the extent that they appear to be in close contact with each other, and may be carried out by hand, but in practice it is suitable to apply a pressure of around 1 kg4. There is. In any case, high-pressure pressing is not particularly required. Note that, depending on the type and amount of the liquid substance, a part of the resin composition held in this state is dispersed within the cotton-like sheet material, but is not impregnated throughout. The subsequent heat treatment is
This is carried out by heating to a temperature below the melting temperature of the resin composition. At this time, it is preferable to carry out the process at a temperature and atmosphere where the liquid substance present in the cotton-like sheet material can easily escape, and it is usually carried out at a temperature of about 40 to 70°C in a dryer. Are suitable. Through such heat treatment, the resin composition is softened by the presence of the liquid substance even though it is below its melting point, and penetrates uniformly into the inside of the cotton-like sheet, and the liquid substance is gradually volatilized and removed. A plate-shaped foamed composite is obtained in which the inside is uniformly impregnated and each cotton-like sheet material and face material are laminated together. Note that the amount of the resin composition interposed and sandwiched is usually 10 to 3
It is suitable to use 4 sheets of 000g.

The plate-shaped foamable composite is placed in a predetermined mold and heated to a temperature at which the resin composition foams and hardens, thereby causing the foaming and hardening and the fiber layer of the sheet material to expand accordingly. Finally, a single-layer or multilayer phenolic resin foam molded product having a composite foam layer in which 111i and the phenol resin foam layer are uniformly mixed can be obtained. In this case, it is suitable to use a mold that can expand in the thickness direction of the above-mentioned plate-shaped foamable composite, and the composite itself can be formed by laminating multiple sheets according to the desired thickness of the molded product. You may let them. Further, the heating temperature is usually preferably 120 to 200°C, and preferably 150 to 180°C.

An example of the process of the manufacturing method of this invention is shown in FIG. In the figure, A is a cotton-like sheet material (2) impregnated with a liquid substance.
Step B is a step of scattering the resin composition powder (1) on top of the powder, B is a step of scattering a similar impregnated cotton-like sheet material (2) on the spread powder (1).
C is a step of heat-treating at a temperature lower than the foaming/curing temperature of the resin composition to fill the cotton-like sheet material with the resin composition (1') and volatilize the liquid substance; D is an explanatory diagram showing the steps of subjecting the plate-like foamable composite obtained in step C to foam molding in a mold to form a foam layer (3) and expanding the cotton-like sheet material in the thickness direction. be.

Example 1 To 100 parts by weight of novolac type phenol resin initial condensate powder, 10 parts by weight of dinitrosopentamethylenetetramine as a blowing agent and 10 parts by weight of hexamethylenetetramine as a curing agent were added and kneaded using heated rolls. Thereafter, it was pulverized to obtain a powdered resin composition. This foamable resin composition had a 150 mesh residue of 2.4% and a melting point of 80°C.

Next, methyl alcohol (reagent special grade) was used as a binder.
and trichlorotrifluoroethane in a volume ratio of 1:5, and sprayed into a 25 cm x 25
5g of the solution was sprayed onto a polyester nonwoven fabric having a thickness of 400μ. 30 g of the above foamable resin composition was spread on the nonwoven fabric that had absorbed the binder, and then the nonwoven fabric that had also absorbed the binder was placed on top of it, preformed at a pressure of about 1 ka61, and then heated at 60°C. 100℃ in a hot air circulation constant temperature bath
Dry heat for minutes.

The resulting sheet-like foamed composite has a thickness of approximately 800 mm.
The structure was yellowish at μ, and the foamable resin composition was uniformly melted and dispersed between the nonwoven fabrics, completely filling the voids in the nonwoven fabrics.

Next, this sheet-like foamable composite was mixed into 22QIX22a.

Place it in a metal mold (22 x 22
Holds time. Thereafter, the mold was taken out of the thermostatic oven, and the foamed molded article was taken out from the mold.

The resulting foam molded product was a foamed sheet that filled the entire mold, and all the voids were uniformly filled with a yellowish novolac type phenolic resin foam layer with a dense cell structure, which was used as a surface material. The structure was such that the nonwoven fabric was located on the upper and lower surfaces of the molded body and was integrated with the foamed molded body.

Incidentally, the density of this molded body was 110 kg4.

Example 2 A novolac type phenolic resin composition similar to that used in Example 1 was prepared.

Next, water is used as a binder and sprayed in a mist form from a nozzle.
5g of 53X25al was sprayed onto a 200μ thick glass fiber mat. Spread 1 og of the above foamable resin composition on the glass fiber mat that has absorbed the binder, place the glass fiber mat that has also absorbed the binder on top of it, and while heating it to about 10°C, It was preformed at a pressure of about 1 kQ4, and then dried and heated for 3 hours in a hot air circulation constant temperature bath at 70°C.

The resulting sheet-like foamed composite has a thickness of approximately 300 μm.
The foamable resin composition is glass l11111.
It penetrated uniformly between the mats, formed a melted film and dispersed, and further integrated the two glass fiber mats.

This operation was further repeated to adjust three sheets.

Next, cut this sheet into 22 x 223 pieces and make a metal mold (2
2X 22X O, 53), the lid was closed, and the mixture was kept in a hot air circulation constant temperature bath at 160° C. for 1 hour.

Thereafter, the mold was taken out of the thermostatic oven, and the foamed molded article was taken out from the mold.

The resulting foamable molded product is a foamed sheet that fills the entire mold, and all the voids are filled with a novolak-type phenolic resin foam layer with a yellowish, dense cell structure. However, it was a composite foam molded product dispersed in a foam layer.

Incidentally, the density of this molded body was approximately 180k (14).

Example 3 10 parts by weight of a blowing agent dinitrosopentamethylenetetramine was added to 100 parts by weight of resol-type phenol resin initial condensate powder, and the mixture was kneaded using heated rolls. Thereafter, it was pulverized to obtain a powdered resin composition. This foamable resin composition had a melting point of 75° C. after 100 mesh passes.

Next, a mixture of methyl alcohol (reagent grade) and trichlorotrifluoroethane in a volume ratio of 1:5 was used as a binder, and a 2501 x 2 atomized mixture was sprayed from a nozzle.
5g of the solution was sprayed onto a polyester nonwoven fabric measuring 5cm and having a thickness of 400μ.

The above-mentioned R foamable resin composition 40Q is spread on the nonwoven fabric that has absorbed this binder, and a 0.21 mm aluminum plate is placed on top of it, preformed at a pressure of about 1 ka4, and then heated with hot air at 60°C. Dry heating was performed for 2 hours in a circulating constant temperature bath.

The resulting sheet-like foamed composite has a thickness of approximately 1 mm.
The reddish-brown foamable resin composition was uniformly melted into a film, dispersed, and bonded between the upper aluminum plate and the nonwoven fabric, and the voids in the nonwoven fabric were also completely filled.

Next, cut this sheet into 223x22cm, place it in a metal mold (22x 22x O, 501), close the lid,
It was kept in a hot air circulation constant temperature bath at 160°C for 1 hour. Thereafter, the mold was taken out of the thermostatic oven, and the foamed molded article was taken out from the mold.

The resulting foam molded product is a foamed sheet that fills the mold, and all the voids are uniformly filled with a dark yellow resol type phenolic resin foam layer with a dense cell structure, and the aluminum used as the surface material. The plate and nonwoven fabric were located on the upper and lower surfaces of the molded body, and the structure was integrated with the foamed molded body.

Incidentally, the density of this composite molded body was approximately 300 kg/m'.

Comparative Example 1 A novolac type phenol resin composition similar to that used in Example 1 was prepared.

30 g of this powdered resin composition was added to a
x 22aa on a 400μ thick polyester non-woven fabric without any binder. Further, a similar nonwoven fabric was placed on top of it to form a sandwich.

This sheet allows the powdered resin to easily move during handling.
It was extremely difficult to handle. This sheet was placed in a metal mold <22X 22X O, 53>, the lid was closed, and the mold was kept in a 160° C. hot air circulation constant temperature bath for 1 hour. Thereafter, the mold was taken out of the thermostatic oven, and the foamed molded article was taken out from the mold.

This foamed molded product had pores everywhere that were not filled with the phenol foam layer, and was obviously non-uniform. Incidentally, the density of this foam molded product is 120 Yu/m
"Met.

Comparative Example 2 A novolac type phenolic resin composition similar to that used in Example 1 was prepared.

This powdered resin composition 30Q was mixed with the same 25X as in Example 1.
No. 253 was applied onto a polyester nonwoven fabric having a thickness of 400 μm without using any binder. A similar nonwoven fabric was placed on top of it to form a sandwich.

The sheet was carefully placed on a hot plate press to prevent the powdered resin in the sheet from moving as much as possible, and was heated to 100° C. and molded at a pressure of ka/cj for 10 minutes.

The obtained sheet was approximately 1 mm thick and had a deep yellow color, and the foamable resin composition was melted and formed into a film, but was dispersed in a mottled and uneven state, with a slightly foamed state near the center. It was a sheet.

Next, cut this sheet into 22x22cm pieces and make a metal mold (
22x 22x 005 pieces), close the lid, and
It was kept in a hot air circulation constant temperature bath at 0°C for 1 hour. after that,
The mold was taken out of the thermostatic oven, and the foamed molded article was taken out from the mold.

This foam molded product is a foamed sheet that fills the entire mold, and although all the voids are filled with a yellowish novolac type phenolic resin foam layer, there are some areas with large bubbles. The molded product was non-uniform and had areas with extremely low magnification.

Incidentally, the density of this foamed molded product was 110 kg/m''.

(C) Effects of the Invention According to the manufacturing method of the present invention, it is possible to efficiently obtain a composite phenolic resin foam molded article having a composite foam layer in which fibers and a phenolic resin foam layer are uniformly mixed. This method does not require heat treatment above the melting point of the resin composition as in conventional methods during preforming, and does not require high-pressure press treatment, making the work extremely simple.
In addition, it is possible to obtain a uniform composite phenol resin foam molded article without particularly strict control, making it an extremely useful method industrially.

[Brief explanation of the drawing]

FIGS. 1A to 1D are configuration explanatory diagrams illustrating each step in the manufacturing method of the present invention. (1)...Resin composition powder, (1')...
...resin composition, (2... cotton-like sheet material, (3
)...Foam layer.

Claims (1)

[Claims] 1. A powdered resin composition consisting of a phenolic resin initial condensate, a decomposable blowing agent, and a curing agent added as necessary is impregnated with a volatile liquid substance that is compatible with the phenolic resin initial condensate. The resin composition is sandwiched between a plurality of cotton-like sheet materials impregnated with the liquid substance and/or between a cotton-like sheet material impregnated with the liquid substance and a predetermined face material, and heat-treated at a temperature lower than the melting temperature of the resin composition itself. By this, a plate-shaped foamable composite is obtained in which the inside of the cotton-like sheet material is uniformly impregnated with the resin composition and the cotton-like sheet materials are integrated with each other and/or the cotton-like sheet material and the face material are integrated. , by heating this foamable composite in a mold above the foaming/curing temperature of the resin composition to obtain a molded article having a composite foam layer in which fibers and a phenol resin foam layer are mixed. A method for producing a composite phenolic resin foam molded product.