KR820002068B1 - Novel expandable particles of a styrene polymer - Google Patents

Abstract

The application of a liq. triglyceride of a fatty acid to expandable particles of a styrene polymer contg. a foaming agent shortens the cooling time during molding of the particles without increasing the water content on the surface of the moldings. Thus, 10kg expandable polystyrene contg. 4% butane-propane foaming agent was mixed with 21g glycerol triester. The particles were preexpanded by heating for 140sec, added to poly(vinylidene chloride), and shaped into pieces suitable for use as thermal insulation.

Description

New foamable styrene resin particles

The present invention relates to a novel foamable styrene resin particles.

The present invention is an ester of aliphatic carboxylic acid and aliphatic alcohol on the surface of a styrenic resin particle containing a blowing agent, which does not have a hydroxyl group in the structure, and can exist as a solid state compound at room temperature, thereby greatly reducing the cooling time during molding. The present invention relates to expandable styrene resin particles.

The method widely used in the production of styrene resin foams is first heated by styrenic resin particles by steam, expanded expansion (primary foaming), and left for a certain period of time (aging), and then small pores and gaps are formed. It is filled into a metal mold, and then heated by steam (secondary foaming), the metal mold is cooled, waiting for a decrease in the foam pressure in the molded body, the mold is opened, and the foam molded body is lifted out. In this process, the long and short cooling time of the metal mold has the greatest influence on productivity.

Therefore, although the cooling time is shortened during the molding of the styrene resin foam, such a request is made of a large-density cube (13-17 g / l. About that, it was a strong one. In recent years, however, relatively high density low to medium foams (25 to 200 g / l, volume multiples of 25 to 40) have been used for structural parts having heat insulation. Because of the nature of the product, strict dimensional accuracy is required, and there is a need to mold the parts of the structural parts so as not to cause distortion due to the foam residual pressure during heating and shrinkage due to excessive cooling.

Therefore, since cooling at the time of shaping | molding takes a long time simultaneously with making it slow, reduction of the cooling time at the time of shaping | molding is especially requested | required.

For large cubes, called appendixes, several experiments have been conducted to reduce the cooling time during this molding.

For example, US Pat. No. 2,989,782 discloses a liquid organic compound having a boiling point of 100 ° C. or more on the outer surface or surface of the expandable styrene resin particles, for example, aromatic compounds such as benzene, chlorinated hydrocarbons such as chlorobenzene, and dimethyl phthalate. It is described that the molding time can be shortened by having an alkyl ester of phthalic acid, or linseed oil, a monoglyceride of a fatty acid having 12 to 20 carbon atoms, and the like. However, according to this method, since the liquid organic compound has a high affinity with the styrene-based resin, the liquid organic compound penetrates into the vicinity of the surface of the expandable styrene-based resin particles and has a plastic effect. In some cases, the particles before foaming may stick to each other, and blocking is likely to occur during primary foaming. In addition, the liquid organic compound penetrates into the interior during the storage of the expandable styrene resin particles, which has the drawback that the effect is significantly reduced. In the case of the present invention, a foaming agent is used in the liquid state at room temperature and atmospheric pressure. However, in most cases, when the electro-liquid organic compound is applied to styrene resin particles containing a gaseous blowing agent at normal temperature and pressure, Electrical defects increase rapidly and cannot be provided for practical use. In the case of gas blowing agents at room temperature and atmospheric pressure, the pressure exerted on the inside of the particles is large and cracks tend to burst, which is because they diverge quickly due to the crack and lose foaming performance.

Further, West German Patent Publication No. 2,133,253 covers the surface of a foamed styrene resin particle with a lipophilic surfactant, specifically, a mixture of mono, di- and triesters of glycerin and saturated fatty acid. It is described that shortening of the cooling time at the time and good fusion between the foamed particles can be achieved.

However, the present inventors, as described later, in the formation of the partial ester of glycerin and saturated fatty acid, which are lipophilic surfactants, and the structure of these partial esters, other than the structural part having a hydroxyl group, that is ester Dominated by the structural part, such a surfactant is hydrophilic by hydroxyl groups, and during foaming, surface adhering water of primary foamed particles increases due to condensed water of steam, and also in the molded body during formation. It has been found to have the drawback that the water content of is increased.

The inventors of the present invention have solved such a drawback that styrene resin particles containing a gaseous blowing agent at room temperature and atmospheric pressure have no triglycerides of triglycerides of liquid fatty acids exemplified by linseed oil. It has been found that when applied to the present invention, a great effect is shown in shortening the cooling time during molding.

However, there have been cases where cracks of the particles occur due to the penetration of the triglyceride of the liquid fatty acid into the expandable styrene resin particles. However, as a result of further studies, the present inventors found that solids at room temperature as esters of aliphatic carboxylic acids and aliphatic alcohols, for example, as triglycerides of fatty acids, are more excellent. That is, compared with the case of the fatty acid-triglyceride in the liquid state at room temperature, the blocking phenomenon at the time of the first foaming is further reduced, there is no fear of electrical defects due to penetration into the expandable styrene resin particles and In the case of long-term storage, there is no reduction in the effect of shortening the cooling time during molding, and the addition of the ester to the expandable styrene resin particles by a mixing machine or the like is easy by using the ester as a powder state.

Furthermore, the present inventors have conducted a series of studies on the effect of esters of fatty acids on shortening of the cooling time during molding of the expandable styrene resin particles. As a result, a compound having a hydroxyl group in the structure has no shortening effect on cooling time. Or found to be significantly smaller. That is, a compound having a hydroxyl group in the carbon chain, for example, triglyceride of hydroxy unsaturated fatty acid (main component of castor oil) and triglyceride of hydrogenated hydroxy saturated fatty acid (common name, hardened castor oil) have no effect. In addition, in the ester of polyhydric alcohol and general fatty acid, in the case of partial ester, the higher the ratio of the remaining alcohol moiety, the smaller the effect.

In addition, when the hydroxyl group in the ester structure of fatty acid is coated on the surface of the styrene resin particles, the particles are made hydrophilic to increase the water functionality during primary foaming or secondary foaming by steam, It takes extra drying time to remove water, and in case of the container or structural parts where the molded body comes into contact with ice such as fish box, water, etc., it is easy to cause leakage and absorption of the molded body itself in the part where internal fusion is incomplete. To have.

Furthermore, Special Publication No. 39-22212 discloses isopentane in a liquid state at room temperature and atmospheric pressure as a blowing agent in styrene resin particles, as a nucleating agent, paraffinic hydrocarbons, saturated or unsaturated nitriles, or 10 to 60 carbon atoms in the carbon chain. When it has a saturated or unsaturated and substituted or unsubstituted fatty acid ester of aliphatic alcohol, etc., there is a description that a foam having fine and uniform cells is obtained. However, the present invention is directed to the surface or near the surface of the expandable styrene resin particles. The presence of an ester of an aliphatic carboxylic acid and an aliphatic alcohol (without a hydroxyl group in the molecule) achieves a shortening of the cooling time during molding and basically differs in purpose, composition, and effect from the known art.

The first first invention is an ester of an aliphatic carboxylic acid and an aliphatic alcohol, which does not have a hydroxyl group in the molecule, and attaches a solid ester at room temperature or a mixture of a finely divided agent of the ester to the surface of the expandable styrene resin particles. It relates to a novel foamable styrene resin particles.

The ester of the aliphatic carboxylic acid and the aliphatic alcohol used in the present invention meets the following conditions. The first is to have no hydroxyl in the structure. When hydroxyl group exists, it exists in carbon chain like ester of hydroxy fatty acid, and it exists as non-esterified alcoholic hydroxyl group like ester of polyhydric alcohol and fatty acid. In some cases, this means that no case exists in the present invention. The reason why this condition is added is that if there is a hydroxyl group in the molecule as described above, there is no shortening effect of the cooling time at the time of molding or it is small, and since the hydroxyl group acts as a hydrophilic group, foaming by steam This is because it is easy to cause an accident of increasing the water content of the foamed molded product at the time, and also the giant hydrophilicity of the incomplete part of the molded product itself.

The second condition is that in the solid state at room temperature and atmospheric pressure, preferably in the range of the melting point of 50 ℃ to 110 ℃.

The reason for the solid state is to prevent the cracking of the particles caused by the penetration of the ester of fatty acid carboxylic acid and aliphatic alcohol into the inside of the expandable styrene resin particles as described above, and to penetrate deeply into the particles to reduce the effect. To prevent.

The preferable range for melting | fusing point is for the following reason.

It is preferable that the melting point of 50 ° C. or more is that when the surface of the expandable styrene resin particles is coated with an ester of a solid aliphatic carboxylic acid and an aliphatic alcohol, the particle size of the ester has a large effect in order to coat efficiently. Particularly, fine powder finer than 60 mesh is preferable, but it is difficult to make powder having a melting point of less than 50 ° C finer than 60 mesh, and even in the case of fine powder by freeze grinding, etc. This is because it is easy to solidify again and form a lump.

It is preferable that melting | fusing point is 110 degrees C or less, The temperature in the molded object at the time of secondary foam molding sets the lower limit to 110 degreeC normally, and melt | dissolves the said ester below this temperature, and foaming polystyrene system at the time of shaping | molding This is in order not to inhibit the mutual fusion of the resin particles.

Illustrative ester compounds of aliphatic alcohols and aliphatic carboxylic acids conforming to the above two conditions include aliphatic alcohols such as pentyl alcohol, hexyl alcohol, octyl alcohol, deganyl alcohol, lauryl alcohol, palmityl alcohol, stearyl alcohol, beh There are monohydric alcohols such as heyl alcohol, dihydric alcohols such as ethylene glycol, propylene glycol, trihydric alcohols such as glycerin, and tetrahydric alcohols such as pentaerythritol, and as aliphatic carboxylic acid, for example, lauric acid, palmitic acid, stearic acid , Unsaturated monobasic acids such as saturated monobasic acid, oleic acid, linoleic acid, such as allazinic acid and behenic acid, and dibasic acids such as adipic acid, succinic acid, sebacic acid, and maleic acid. It is an ester which does not contain the hydroxyl group of such aliphatic alcohol and aliphatic carboxylic acid.

Among the esters, some of these esters are contained in the materials marketed under the names, for example, hydrogenated oil, hydrogenated oil, hydrogenated fish oil, and hydrogenated lead.

Although the use amount of the said ester needs to consider the magnitude | size of particle | grains, ie the magnitude | size of a specific surface area slightly, it is 0.03 to 0.5 weight% normally with respect to foamable styrene resin particle. If the content exceeds 0.5% by weight, the effect of shortening the cooling time is so strong that partial shrinkage may occur in the molded article, and the mechanical strength of the finally obtained molded article appears.

At less than 0.03% by weight, the effect is too small. Preferably 0.05 to 0.3% by weight is used. In general, there is a sufficient effect at 0.3% by weight or less, and if it is more than that, a part of the ester may be released during air transportation of the expandable styrene resin particles, which may cause a hole in the filter of the air transportation device. The ester may partially penetrate near the surface of the expandable styrene resin particles.

The expandable styrenic resin particles used in the present invention include a blowing agent to the styrene resin particles, and in some cases, a solvent having affinity with the styrene resin as a plasticizer, or a bubble adjusting agent, an anti-blocking agent, or the like. It is present containing.

The styrene resin is, in addition to the homopolymer of styrene, for example, less than half of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, hydroxyethyl methacrylate, acrylonitrile, α-methyl styrene, butadiene , Copolymers with divinylbenzene, ethylene glycol, dimethacrylate, and the like, or mixtures with other polymers based on polystyrene, for example, a mixture of polystyrene and polystyrene, Refers to a mixture of polystyrene and polyphenylene oxide.

The blowing agent is a gaseous petroleum hydrocarbon at normal temperature or atmospheric pressure, or a mixture with a foaming agent in a liquid state at normal temperature and atmospheric pressure mainly containing the same. At room temperature, the liquid state and the blowing agent are n-pentane-, isopentane, neopentane, n-hexane, isohexane, etc., but they remain in the particles for a long time after the primary foaming, and in the second foam molding, The effect of the cooling time by addition and coating agent is reduced.

Therefore, the blowing agent used in the present invention is preferable only if it is a mixture of only a gaseous blowing agent or a main component at room temperature, normal pressure, such as n-butane, isobutane, propane, methyl chloride, dichlorodipoormethane, and together with a liquid blowing agent. When it does, it is preferable to set it as less than 50 weight% of the total foaming quantity.

The presence or absence of the plasticizer contained therein, its kind, and the amount used thereof are not limited. Examples of the plasticizer include aromatic hydrocarbons such as styrene monomer, ethylbenzene, and toluene, and chain aliphatic hydrocarbons such as cycloaliphatic hydrocarbons such as cyclohexane and cyclopentane, heptane, and octane. .

Examples of the finely divided agent include metal soaps such as zinc stearate, calcium stearate, aluminum stearate, and cadmium stearate, and fatty acid amides such as ethylene bis stearamide, methylene bis stearamide, and stearic acid amide.

The ester exhibits sufficient effects even when used alone, or when used in admixture with the above-mentioned fine powder, to produce several secondary effects. The fine powder is particularly preferably an ultra fine powder having a finer particle diameter than 300 mesh.

Among the above esters, in particular, when the melting point is about 70 ° C. or less, the obtained expandable styrene resin particles are particularly stacked below when they are stacked and stored in a bag. This results in a significant reduction in the performance of the present invention and the need for regrinding. This can be prevented by mixing the fine powder with the esters in advance. It is considered that this is because the fine lubricating agent adheres and protects the surface of the ester powder to act as a dispersant of the ester. As for the usage-amount of a fine grinding | polishing agent, the weight ratio of ester to a fine grinding | pulverization agent is 100-100-100-3 as preferable range of 100-100.

As a method of presenting an ester of an aliphatic carboxylic acid aliphatic alcohol on the surface of the expandable styrene resin particles, a method of mechanically mixing the ester in a powder state with the expandable styrene resin particles, lower esters of metholethanols, pentane, Although dissolved in lower aliphatic hydrocarbons such as hexane and the like, mixed with expandable styrene resin particles, and then volatilized and removed, the former method is preferable. A particularly effective method is a method of mixing and kneading a powder having a particle size finer than 60 mesh of the ester, preferably finer than 100 mesh, with the expandable styrene resin particles to coat the surface of the particle as the ester.

The second invention is an ester of an aliphatic carboxylic acid and an aliphatic alcohol, which does not have a hydroxyl group in the molecule, has a solid form at room temperature, and has a melting point of 50 to 110 ° C. and a particle diameter of 60 mesh or more and the ester and finely divided agent. The present invention relates to a method for producing novel foamable styrene resin particles, wherein the mixture is stirred and mixed with expandable styrene resin particles.

Here, the said ester, expandable styrene resin particle, a fine powder, and a compounding ratio thereof are as above-mentioned.

When the fine powder is mixed with the ester, addition of the fine powder to the surface of the expandable styrene resin particles by stirring and mixing of the ester powder is facilitated, and uniformity is increased. In particular, when carrying out the batch type automatic mixing tank (Hencierumic company) which has a stirring blade which rotates at high speed, the said esters and a screw-woo feeder fall down the center of a pipe, Since the fluidity of the powder body has a great influence on the quantitative addition, the ester powder alone lacks this fluidity and may stay in the feeder, but this defect can be eliminated by mixing and using a fine powder. . At the same time, due to the improvement of the activity and fluidity in the mixing tank, the generation of frictional heat between the particles is reduced and the uniform coating can be achieved in a short time.

In addition, even if the ester of the aliphatic carboxylic acid and the aliphatic alcohol in the solid state at room temperature, the melting point of less than about 70 ℃ is remelted and adhered to the impact heat during grinding, it is difficult to make a fine powder in the usual method, dry It needs to be pulverized while cooling with ice or liquid nitrogen.

Next, an embodiment of the present invention will be shown. In addition, "%" means "weight%" in an Example.

Example 1

10 kg of expandable polystyrene particles having a diameter of 1-1.2 mm were prepared. This is a 1% solution of toluene and a relative viscosity of ubbelohde viscometer at 2.1C at 30 ° C, which is 2.1, and polystyrene contains 1.5% ethylbenzene and styrene monomer 0.2% propane / butane = 4/6 It is 4% of blowing agent and 0.08% of ethylene bis stearamide is added to the surface.

On the other hand, a saturated fatty acid mixture composed of 63% stearic acid, 30% palmitic acid, 4% myristic acid, and 3% of other fatty acids, and glycerin triester with glycerin having a rising melting point of 59 ° C. (Japanese fats and oils, Uji extremely hardened oil) 10 kg of the state article (flakes) was prepared, 5 kg of dry ice crushed materials were mixed, and ground in an impact mill.

From this, triglycerides of saturated fatty acids in a finely divided state were obtained. Next, 5 kg of this powder was added 0.25 kg of zinc stearate and mixed well. Next, 21 kg of the prepared fine powder of effervescent polystyrene and 21 kg of a mixture of triglyceride of saturated fatty acid and zinc stearate were added to a high speed mixer (SMV-20 manufactured by Kawada Co., Ltd.), and stirred and mixed for 40 seconds.

1 kg of this was taken out and heated in steam for 2 minutes and 20 seconds, and it foamed by 33 times the volume ratio. There was no blocking or leakage of the particle surface.

The foamed particles were placed in a net of polyvinylidene chloride and allowed to stand for 24 hours, followed by a molding test. The cooling time, internal fusion degree, and moisture content during molding were measured.

The cooling time was measured by the following method. The molding condition is a heating method in which the time until the internal pressure reaches 1.2 kg / cm 2 is 30 seconds by steam of 3 kg / cm 2 of original pressure, and after completion of heating, water is passed through the outside of the mold. When the mold surface temperature approached 70 ° C., the coolant was stopped, and after that, it was left to cool and the temperature at which the molded bodies were taken out was about 70 ° C.

The metal mold | die used for shaping | molding has a part of 50x75x400 / m / m in a thick part, and 10x75x400m / m as a thin part. This assumes a heat insulating material and a structural part which isolate | separate the freezer compartment and the refrigerating compartment of a two-stage door refrigerator. If the cooling time is short and the cooling is insufficient, the 50m / m thick part swells and leans to the thin part, and the crooked change occurs, but when the cooling is performed at an appropriate temperature, the thick part becomes 49 to 50 m / m and leans to the thin part. There is no loss, no crooked change.

The cooling time was measured by the sum of the time required for cooling the water and cooling the air, which is necessary for the thick part of the molded body to be 50 m / m when the mold was opened.

Water content (%) during molding

As a numerical value expressed as, the degree of fusion indicates the percentage of particles broken at the time of breaking the 50 m / m thick portion, not from the grain boundary.

A molded article absorption rate is measured according to Japanese Industrial Standard A-9511-1974, and an absorption rate is obtained by the following formula.

The above measuring methods and measured values are common to the following examples.

In this example, the cooling time was 130 seconds, the water content 13% internal fusion during molding was 80%, and the molded article absorption rate was 4.6%.

Example 2

In the same materials and methods as those of Example 1, the addition amount of the triglyceride and zinc stearate mixtures of the saturated fatty acid mixture was 10.5 g (the amount of triglycerides 10 g, 0.1% based on the foamable particles). Second, internal fusion was 80%, water content was 10% at the time of molding, and the absorbency of the molded body was 4.1%.

Example 3

As in the same method as in Example 1, the result of only 5.025 g of additives (5 g of triglycerides and 0.05% of the foamable particles) was found to have a cooling time of 190 seconds, a welding degree of 70%, a molding water content of 9%, and a molded product. Absorption rate was 3.3%.

Example 4

Example 1 and 1 kg of ground expandable polystyrene particles were taken, and 10 g of ethyl alcohol heated to 40 ° C. was dissolved in 2 g of cetyl alcohol and palmitate ester (lead hardened by Nippon Co., Ltd.). I) The same evaluation was performed about mixing. Cooling time was 180 seconds, fusion degree 70%, molding water content 13%, molded body absorption rate 5.9%.

Comparative Example 1

When 1 kg of expandable polystyrene particles used in Example 1 were taken and evaluated in the same manner, the cooling time was 270 seconds, the fusion rate was 60%, the water content during molding 9%, and the molded body absorption rate 28%.

Comparative Examples 2 to 5

1 kg of the same foam as the foamed polystyrene particles used in Example 1 were taken, and each of (1) sorbitan monopalmitate, (2) stearic acid, and (3) hydroxystearic acid triglyceride in powder form was separately 0.2%, and separately (4) Ore. Mono and deglyceride mixtures of phosphoric acid were evaluated according to the examples, using the liquid state. All of them had a cooling time of 270 to 230 seconds, which had no shortening effect or was small, and had a high water content of 24 to 34% and a water absorption of 13.6 to 27.2%.

Comparative Examples 6 to 8

1 kg of the same foam as the expanded polystyrene particles used in Example 1 was prepared, and fine powders of glycerides of stearic acid (45% monoester, 45% diester, and 10% trieste) of ① 20 g ② 30 g and ③ 40 g were separately prepared. It mixed and added and evaluated like Example 1.

As shown in the asterisk, the effect was recognized as Comparative Example 2 to 5 for 220 to 190 seconds, but the same addition amount was smaller than that of the Examples of the present invention, and 0.3% or more was added to show almost equivalent shortening effects. Was needed. In addition, the moisture content at the time of shaping | molding in all was 20% or more, and the molded object absorption rate was 10% or more.

Table 1 shows the results of the evaluation of the above examples and comparative examples.

[Table 1 Evaluation Results]

Example 5

Four 10 kg foamable polystyrene particles used in Example 1 were prepared. In addition, 500 g of solid fatty acid triglyceride used in Example 1 was treated for 30 minutes with a bleach, divided into sieves of 30, 60 and 100 meshes, which were rougher than 30 meshes. 4 kinds of triglyceride powders of finer than 2, 30-60 mesh, 3, 60-100 mesh and 4, 100 mesh.

20 g of this was added to the above-mentioned expandable polystyrene particles, charged into a high-speed mixer, and treated for 40 seconds, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Table 2 Test Results

As apparent from Table 2, it can be seen that the smaller the particle size of the triglyceride powder, the more the effect of shortening the cooling time required during molding can be imparted to the expandable styrene resin particles. However, this does not always mean that the particle size of the triglyceride must be small, and in the case where a large particle size is used, a sufficient effect cannot be obtained unless the stirring time is lengthened.

The expandable styrene resin particles according to the present invention can shorten the cooling time by coating the surface of the particles with esters of aliphatic carboxylic acids and aliphatic alcohols in a solid state at room temperature, and a tree of liquid fatty acids at room temperature. The use of glycerides is free from the drawbacks of cracks, cracks, and performance deterioration caused by penetration into the styrene resin during storage, and the efficiency of the addition operation is good.

In addition, the foamed styrene-based resin using a liquid or solid surfactant has a hydrophilic group (OH group) in its structure, which increases the water content during molding by steam, or a container or structure in which the molded body is in contact with water. In the case of parts, it is easy to cause absorption and leakage, but in the foamable styrene-based resin particles according to the present invention, the water content during molding is small, the absorbency in contact with water of the molded body is small, and the thermal insulation due to leakage and absorption of the molded body is reduced. It is difficult to cause a back.

Claims (1)

A novel foamable styrene resin particle having a triglyceride of a fatty acid in solid form or a mixture of the triglyceride and an undivided agent in a molecule having no hydroxyl group in a molecule, on the surface of the expandable styrene resin particle.