JPS5842215B2 - Keiryoutaino Seizouhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a lightweight body.

More specifically, the present invention relates to a method for producing a lightweight body with excellent compressive strength from a phenolic resin blended with a foaming agent and hollow microparticles.

Plastic foams obtained by foaming various plastics are lightweight and have low thermal conductivity, so they are widely used as insulation materials and core materials, but their range of use is limited due to their generally low compressive strength. The current situation is that there are restrictions.

On the other hand, lightweight bodies made of calcium silicate, pearlite, etc. have high compressive strength, but have the drawbacks of low specific gravity, low elasticity, and high thermal conductivity.

A heat insulating material made by blending hollow microparticles with a thermosetting resin such as an unsaturated polyester resin is known (Kokai No. 18957/1989).

However, when mixing hollow microparticles and ordinary phenolic resin and heating and curing the mixture, in order for the phenolic resin to connect and bond between the hollow microparticles, it is necessary to increase the blending ratio of the former. As a result, the specific gravity increases, and it loses its meaning as a lightweight body.

On the other hand, if the blending ratio of the phenol resin is reduced, the specific gravity will be reduced, but the connection between the hollow microparticles will be incomplete, resulting in only crumbly particles with a lot of powder falling off.

Therefore, the desired objective was not achieved in any case.

However, the present inventors have completed the method of the present invention as a result of intensive research to improve the various drawbacks of the above-mentioned conventional methods.

That is, in the method for producing a lightweight body according to the present invention, phenol and formaldehyde are subjected to addition condensation in an aqueous solvent in the presence of an acid catalyst to obtain an aqueous solution of a novolac type phenol/aldehyde initial condensate, and the pH of the aqueous solution is adjusted to 6.5. 7.5, dehydrated and pulverized until the viscosity at 80° C. reached 50 poise or higher to obtain a powdery novolak-type phenol/aldehyde initial condensate, and then the powdered initial condensate (A ) Powdered novolac type phenolic resin (I) containing 20 to 80% by weight of a blowing agent (B) in a ratio of 3 to 10 parts by weight per 100 parts by weight, having closed cells and having a particle size of 0.1 ~1.2 mrn.

80 to 20% by weight of hollow microparticles (III) having a bulk specific gravity in the range of 0.05 to 0.75 are mixed, and the mixture is molded in the presence of a curing agent that can decompose and generate aldehyde when heated. Or heat it in a container at a temperature in the range of 110 to 180°C to foam and harden it so that the coefficient of thermal expansion is 0.4X10-5 or more.
This is done by obtaining a lightweight body in the range 5x10-'.

The powdered novolac type phenol-aldehyde initial condensate (A) used in the present invention contains 1 mol of phenol and 0.5 to 1 mol of formaldehyde or one type of polymer thereof.
0.01 to 5% by weight of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, etc. or organic acids such as benzenesulfonic acid, toluenesulfonic acid, formic acid, oxalic acid, etc. to phenol. present to form an aqueous solution, 80~
Addition condensation is carried out by heating at 100° C. for 2 to 5 hours to obtain an aqueous solution of a novolac type phenol/aldehyde initial condensate,
The aqueous solution is adjusted to a pH of 6.5 to 7.5 with a suitable alkali or alkali-forming substance, such as sodium hydroxide, potassium hydroxide, sodium carbonate, etc., and then transferred to a dehydration step, where the pH is adjusted to 80°C. 50 at °C
It is obtained by dehydrating and concentrating until it exhibits a viscosity of poise or higher, and then pulverizing it.

At this time, if the viscosity is less than 50 poise, it will take a long time to cure and the bubbles will be non-uniform, making it difficult to form a product with commercial value.

In the present invention, phenolic resin is used because, among thermosetting resins, it has particularly strong adhesive strength, and the foamed form of phenolic resin itself has high heat resistance (approximately 1.5
0°C), and has many advantages such as a small coefficient of thermal expansion, excellent chemical resistance, and self-extinguishing properties.

The blowing agent (B) used in the present invention may be any substance that decomposes and generates gas during heating and curing in the composition mixed with the initial condensation novolac type resin and the curing agent.
Either can be used.

Therefore, even dinitrosopentamethylenetetramine, which has a decomposition temperature of 200'C or higher when used alone, decomposes into amines such as hexamethylenetetramine, which is used as a curing agent, when mixed in the initial condensate. It is possible to use those that can accelerate the decomposition temperature and control the decomposition temperature to 120°C or less.

Therefore, there are various blowing agents that can be used, including, for example, dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide,
These include abbisisobutyronitrile, abdicarboxylic acid amide, paratoluenesulfonyl hydrazide, ammonium carbonate, and sodium bicarbonate.

These blowing agents are added in an amount of 3 to 10 parts by weight, preferably 5 to 8 parts by weight, per 100 parts by weight of the initial condensate.

In the present invention, the curing agent added to the initial condensate must be a compound that can decompose during heating to produce aldehyde.

Examples of such compounds include hexamethylenetetramine and paraformaldehyde. Among these, hexamethylenetetramine generates ammonia or amines together with aldehyde when heated, so it accelerates curing and crosslinks the resin. It is the most effective because it completes quickly.

The amount of these curing agents used is 4 to 20 parts by weight, preferably 10 to 15 parts by weight, based on ioo parts by weight of the initial condensate.

To mix the above-mentioned three types of substances, there are two methods: mixing in the form of solid powder, and heating the initial condensate at around 60° C. to make it fluid, and then mixing the curing agent and the foaming agent.

Furthermore, hollow microparticles (II
), particle size of 0.1 to 1.2 with closed cells,
Preferably between 0.2 and 0.6, bulk specific gravity between 0.05 and 0.
75 (preferably one with a bulk specific gravity as small as possible), such as the so-called shirasu balloon, which is made by heating and foaming shirasu, a type of volcanic ash, or the so-called micro balloon, which is manufactured from glass, various plastics, etc. A balloon or the like is suitable.

In particular, if an inorganic material is used, it has the advantage of further doubling the flame retardancy of the phenol resin.

In order to mix the hollow microparticles (II) with the powdered novolac type ferro resin (I) blended with the above-mentioned foaming agent, etc.,
Any conventional method of powder mixing can be used.

The blending ratio of both is 20 to 80% by weight to 80 to 2% by weight.
0% by weight, preferably 40-600-60 parts by weight, 60-40% by weight.

That is, as the proportion of hollow microparticles (1) increases, the compressive strength increases, but the specific gravity decreases, so it is determined according to the purpose of use.

However, if the content of the hollow microparticles (II) exceeds 80% by weight, the connection between the particles by the foamed phenol resin becomes insufficient.

On the other hand, if the hollow microparticles (II) are less than 20% by weight, the compressive strength is significantly reduced.

When molding is performed using only the novolac type phenol initial condensation resin, the novolac type phenol initial condensation resin is loaded into a mold having a desired shape, inserted into a heating furnace or steam press, and heated at 110 to 130'C.

In this case, the temperature of the resin gradually increases, and when the resin becomes plastic and reaches the temperature, the blowing agent decomposes and generates gas, and the resin fills the predetermined mold.

When heated further to reach a temperature of 1.50 to 180°C, the resin hardens and can form a desired molded product.

From the above points, the conditions for molding and heating using only resin are melting,
The process order of foaming, curing, and cooling is a necessary process order to prevent rough foam, cracks, and variations in foam specific gravity in the product, but in the present invention, preheating and melting during molding is unnecessary. , after loading the mixture of (I) and (II) into a desired mold, the heat insulating effect of the hollow microparticles (n) that coexist even if heated all at once to the resin curing temperature in a heating furnace or steam press. As a result, the temperature rise gradient becomes gentler, compared to the case where only the resin is used,
The hot molding time is significantly shortened, the work procedure is simplified, and it is possible to manufacture homogeneous products.

This is because when foaming in a container, when the resin is alone, the plastic state expands while containing gas due to the decomposed gas pressure of the blowing agent, and the container is filled with excess gas pressure. This results in its high specific gravity.

However, in the present invention, hollow microparticles (II
) controls the fluidity of the resin in its plastic state and also contributes to uniformity of specific gravity, which results in good results in terms of the physical properties of the product as shown in Table 1 below.

In some cases, the material may be heated in a heating furnace in a box-shaped container to foam and harden, and then cut into a desired shape.

Therefore, the resulting lightweight body can be used not only as a heat insulating material and core material, but also to prevent cracks (or cracks) caused by concentrated loads, which is a drawback of inorganic foam materials (e.g. cellular glass lightweight concrete, pearlite molded products, etc.). The ease of generation and the severity of wear due to vibration are improved, and the lightweight body obtained by the present invention has a compression creep resistance 1.5 to 2.0 times higher than that of a phenolic resin foam of the same density. It is suitable as a heat insulating material for building floors that require compression stability and as a support material for heat insulation pipes.

In particular, the thermal expansion coefficient of the lightweight insulation material obtained by the present invention is in the range of 0.4 x 10-'' to 5 , for example, -2
It can also be fully used as an insulating material for ultra-low temperatures of 00'C.

Next, the method of the present invention will be explained in more detail with reference to Examples.

In addition, all parts in the following examples are based on parts by weight.

Examples 1-3 A mixture of 1 mole of phenol, 0.8 mole of formaldehyde (used as a 37% by weight aqueous solution) and 0.5% (by weight relative to the phenol) of hydrochloric acid is heated to 95-100' using a reflux condenser. Condensation was carried out by heating at a temperature of C for 3 hours.

Then, the pH was adjusted to 6 using an aqueous solution of sulfur hydroxide.
．． After neutralizing the hydrochloric acid to a concentration of 5 to 7.5, the solution was dehydrated under reduced pressure.

The dehydration was completed when the resin viscosity reached 150 voids in SO'C, and the mixture was then ground to obtain a powdered novolak-type phenol-aldehyde initial condensate.

To 100 parts of the powder thus obtained, 12 parts of hexamethylenetetramine and 6 parts of benzenesulfonyl hydrazide were added and mixed uniformly with a stirrer.

30 parts of the powdered mixture thus obtained, 50 parts
Take part and 70 parts, and add particle size 0.6 to 0.1.5m to this.
70 parts, 50 parts, and 30 parts of shirasu balloons with bulk specific gravity of 0.07 kg/l were mixed in a rotary mixer.

Next, this was supplied to a 30 cr I'L square mold with a depth of 50 mm, and was foamed and cured by heating at 160° C. for 30 minutes in a hot press, resulting in a strong and lightweight body.

Its physical properties were as shown in Table 1.

Comparative Example 1 Powdered initial condensate 10 prepared by the same method as Example 1
60 parts of the same shirasu balloon as used in Examples 1 to 3 were added to 40 parts of a resin mixture obtained by adding 12 parts of hexamethylenetetramine to 0 parts by weight, and the mixture was prepared in the same manner as in Examples 1 to 3. I did the molding.

Although the obtained product had a -6 shape, it was extremely powdered from the surface and was not suitable for practical use.

Comparative Example 2 1 mol of phenol, 1.5 mol of formaldehyde (used as a 137% by weight aqueous solution) and 1% sodium hydroxide
(% by weight relative to phenol) was heated at 95° C. for 2 hours using a reflux condenser to carry out addition polymerization to obtain an aqueous solution of resol type phenol-formaldehyde initial condensate.

Next, the solution was neutralized using lactic acid until the pH reached 6.5, and then dehydrated under reduced pressure.

The dehydration is completed when the resin viscosity becomes 20 poise at 25°C, and the initial condensate thus obtained is 10
To 0 parts by weight, 10 parts by weight of para-toluenesulfonic acid and 5 parts by weight of Freon 11 were added and mixed uniformly with a stirrer.

To 50 parts by weight of the mixture thus obtained, 50 parts by weight of shirasu balloons having a particle size of 0.6 to 0.15 grains and a bulk specific gravity of 0.07 kg/l were mixed using a rotary mixer.

Next, this was supplied to a mold with a depth of 50 mounds and a size of 30 crrL square, and the lightweight bodies (A) thus obtained at room temperature and the lightweight bodies obtained in Examples 1 to 3 were molded with metal having metallic luster. When the pieces were inserted, 24 hours later, rusting was observed only on the metal pieces inserted into the lightweight body (A).

Comparative Example 3 When the same method as in Example 2 was carried out except that the pH of the aqueous solution was adjusted to 5, the resin viscosity at 80° C. was 1000 poise.

This novolac type phenol-aldehyde initial condensate was blended with 50 parts of shirasu balloons in the same manner as in Example 2 to obtain a foam, which had a compressive strength of 3.5 kg/-.

Comparative Example 4 The same method as in Comparative Example 3 was performed except that the pH was adjusted to 9, and the same results were obtained.

Comparative Example 5 In the method of Example 2, the resin viscosity at 80°C was set to 30
When the same method was carried out except that the foam was changed to poise, the foam broke at the foaming stage and homogeneous cells were not formed.

Comparative Example 6 When the same method as in Example 2 was carried out except that the foaming effect was carried out at 100'C or lower, no solidification occurred.

Comparative Example 7 When the same method as in Example 2 was carried out except that foam curing was carried out at 220° C., the resin decomposed and the compressive strength decreased to 15 ky/ffl.

Claims (1)

[Claims] 1. Addition condensation of phenol and formaldehyde in an aqueous solvent in the presence of an acid catalyst was carried out to obtain an aqueous solution of a novolac type phenol/aldehyde initial condensate, and the pH of the aqueous solution was adjusted to 6.
After adjusting it to a range of 5 to 7.5, it is dehydrated and pulverized until the viscosity at a temperature of 80°C becomes 50 poise or more to obtain a powdery novolac type phenol/aldehyde initial condensate, and then the powdered initial condensate ( A) Powdered novolac type phenolic resin (I) containing 20 to 80% by weight of a blowing agent (B) in a ratio of 3 to 10 parts by weight per 100 parts by weight, and having closed cells and a particle size of 0. Hollow microparticles (I) in the range of 1 to L2rnm and bulk specific gravity of 0.05 to 0.75
80 to 20% by weight, and the mixture is foamed and cured by heating in a mold or container at a temperature in the range of 110 to 1800 C in the presence of a curing agent that can decompose to produce aldehyde when heated. The characteristic coefficient of thermal expansion is 0.4X1
A method for manufacturing a lightweight body in the range of 0-5 to 5X10-5.