KR840001491B1 - Method of producing for foamable polymeric composition - Google Patents

Abstract

Low-density, foamable, polymeric compsns. are prepd. by mixing thermally plasticized resins with a foaming agent under an elevated pressure; adding 1.0-10 wt.% glycol ester of fomula [(R1CO)l(OR2)mO nM to the mixt.; and passing the products to a low-temp., low-pressure zone. R1 is an aliphatic C10-24 radical; R2 is an aliphatic C1-5 polyhydric alcohol resin residual; l is an integer, which is greater than l and less than [(atomic valency of alcohol in R2)-1 ; m is an integer, which is greater than l; and the number of C in R1/(mx(no. of C in R2)/(atomic valency of alcohol in R2))>=0.8; n is 1-3; and M is boric acid or phosphoric acid residual.

Description

Manufacturing method of foamable synthetic resin

FIG. 1 is a graph showing foam volume (in% volume based on initial foam volume) as a function of time required for foaming formed in Test 1 of Operation Example 1 and Test 1 of Comparative Example 1. FIG.

FIG. 2 is a graph showing foam weight (in weight percent based on initial foam weight) as a function of time required for foaming formed in Test 1 of Operation Example 1 and Test 1 of Comparative Example 1. FIG.

The present invention comprises in the thermoplastic synthetic resin in an amount of 0.1 to 10% by weight of one or more compounds which prevent leakage of the blowing agent gas from the foaming material, improve the gas efficiency of the blowing agent and prevent significant shrinkage of the foaming material. It relates to an expandable synthetic resin composition.

Generally, thermoplastic resin foams are added to a resin in a plastically heated form and the foaming agent is vaporized to give the desired thermoplastic resin foam. Typical blowing agents used are relatively expensive materials. Therefore, improvement of the gas efficiency of the blowing agent is very important in the industrial field.

It is very difficult to foam the polyolefin resin in an unchanged form in the thermoplastic resin. This is because the thermofluid viscoelastic properties of polyolefin resins are significantly dependent on temperature during the melting process, and thin films or membranes forming bubble walls in the foamed resins may allow gas to penetrate and thus require gas pressure in the foam. This is because it is difficult to maintain. This factor has a complex effect on heat absorption, swelling and heat of crystallization generated during foaming, and therefore it is difficult to set foaming conditions. As a result, in the foaming of the polyethylene resin, in particular in the high foaming drainage or the high foaming ratio (about 5 or more), the foaming is essentially combined with the resin modified by crosslinking-modified resin or by mixing with another resin. It is common sense to carry out.

As an exception, a technique for extrusion foaming of a comparatively bonded polyolefin resin is described in Japanese Patent Laid-Open No. 4431 (1960). However, this method is economically disadvantageous because it cannot be carried out except by a relatively expensive blowing agent such as 1,2-dichlorotetrafluoroethane. In addition, the foam obtained shrinks gradually over time resulting in the inability to obtain a foam of the intended density without recovering (and gradually recovering) to its original size. Even if the size recovers (or gradually recovers), a relatively long time is required and sometimes deep wrinkles remain on the surface of the foam, making the appearance of the formed product undesirable. Therefore, a problem related to the scaling which has not been solved yet is a disadvantage.

The present invention has been developed in the above state, and thus, the production of thermoplastic foams economically and in particular in the case of the non-crosslinked polyolefin resin, the foam obtained by easily forming the foam does not shrink over time. It is an object to obtain a foamable thermoplastic synthetic resin composition having good dimensional stability and surface smoothness.

As described above, the present invention relates to a expandable thermoplastic synthetic resin composition containing a glycol ester compound of formula (I) or more.

In the above general formula,

R ₁ is aliphatic hydrocarbon radical having 10 to 24 carbon atoms,

R ₂ is an aliphatic polyhydric alcohol resin residue having 1 to 5 carbon atoms,

l is a positive number greater than 1 and less than [(alcohol atoms of R ₂ group) -1],

m is a positive number greater than 1 that satisfies

n is a positive number from 1 to 3,

M is boric acid or a phosphate residue.

In the above-mentioned resin composition, the compound of general formula (I) serves to suppress the leakage (or foaming) of the blowing agent during the manufacture of the foamed product from the composition, which is not known but novel.

In the glycol ester compounds of the essential formula (I) in the present invention, R ₁ of the general formula R ₁ CO unit of the aliphatic hydrocarbon residue having a carbon number of 10 to 24 is undecanoate acid, La Ulsan, myristic acid, stearic acid, arachic acid, and The carbonyl containing residue of fatty acids, such as behenic acid, is shown. These can be used in the form of a single or a mixture. These carboxylic acids are generally prepared from natural oils and fats because they are present in mixtures in most cases and may contain some unsaturated aliphatic hydrocarbon residues. These mixtures can also be used suitably.

R ₂ is a hydrocarbon moiety of an aliphatic polyalcohol residue having 1 to 5 carbon atoms, for example referring to methylene, ethylene, trimethylene and tetramethylene groups (containing isomers). The polyhydric alcohol which can be used is a C3-C5 glycol or polyglycol ether of polyhydric alcohol chosen from compounds, such as glycerin, erythritol, pentaerythritol, and arabitol, for example. L, m and n are positive and are determined stoichiometrically according to the choice of R ₁ , R ₂ and M (borate or phosphate residues) mentioned above. For single compounds this value is an integer. However, mixtures are often used as industrial products and may be classified as averages for the mixture as a whole when the mixture is used.

When R ₁ is less than 10 or greater than 24, the effect of the present invention cannot be obtained. The reason for this is not clear, but it is considered to be due to the solubility and aggregation characteristics of the compound of the general formula (I) in the resin. 13 to 17 carbon atoms are preferable. Moreover, even if carbon number is larger than 5 in R <_2> , the effect of this invention cannot be acquired. This reason is also considered to be due to solubility and aggregation characteristics as described above. Moreover, the effects of the present invention are suppressed by compounds in which m is a positive number satisfying the following formula.

In the case of using a material that does not satisfy this essential condition, it is not preferable because of the solubility in the resin and the coagulation property, and the object of the present invention cannot be obtained.

Examples of representative compounds of general formula (I) include tri- (1-stearyl-glycero-3) borate, tri (1,2-distearyl-glycero-3) borate, tri (monostearyl polyethylene glycol ) Borate, tri (monostearyl polypropylene glycol) borate, di (1-stearyl-glycero-3) phosphinic ester, di (1,2-distearyl-glycero-3) phosphinic ester, di (Monostearyl polyoxyethylene glycol) phosphinic ester, di (monostearyl polypropylene glycol) phosphinic ester, tri (1-palmyl-glycero-3) borate, tri (1,2-dipalmityl- Glycerol-3) borate, tri (monopalmitylpolyoxyethylene glycol) borate tri (monopalmitylpolypropylene glycol) borate, di (1-palmityl-glycero-3) phosphinic acid ester, di (1,2 -Palmityl-glycero-3) phosphinic acid ester, di (monopalmitylpolyoxyethylene glycol) phosphinic acid Esters and di (monopalmitylpropyleneglycol) phosphinic acid esters.

The amount of the compound of formula (I) added in the practice of the present invention should be at least 0.1% by weight or more per weight of the resin and the total amount should be 0.1 to 10% by weight. It is preferable to select this amount according to the shape and characteristic (density, mechanical property, etc.) of resin and foaming agent which are used, and foam. However, 0.3 to 7% by weight is particularly preferable. When the amount is 0.1% by weight or less, the appearance of the foam is considerably lowered (wrinkle, shrinkage), so that it is impossible to obtain a preferable foam. In addition, the properties of the obtained foam also deteriorate. On the other hand, when 10% by weight or more is used, there is no improvement in terms of effects of the present invention and there is an economic disadvantage. In addition, the plasticizing effect is suppressed, and the properties of the foam are also reduced, which is not preferable.

The thermoplastic resin which is a component of the present invention is a copolymer of styrene and other monomers copolymerizable with polystyrene and styrene, and an olefin polymer resin. Olefin polymer resins in which olefins are the sole or important component, for example, low density polyethylene, medium and high density polyethylene, isotactic polypropylene, polybutene-1, copolymers of ethylene or propylene with monomers copolymerizable with ethylene or propylene (E.g., propylene-octene-1-ethylene copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinylchloride copolymer and ethylene Zinc, sodium, calcium and magnesium salts of acrylate copolymers. This resin can be used alone or in the form of a mixture.

The compounds of the present invention can be introduced into the resin by kneading or heating using kneaders such as single screw extruders, twin screw extruders, rollers and Banbury mixers. Other methods include dry mixing and master batch methods and fusion injection methods.

Known methods can be used to obtain the foams using the components of the invention. For example, a method in which extruded foaming is carried out at low pressure by heating and melting the resin component of the present invention, mixing the blowing agent, and melting at high temperature and high pressure, and placing the foaming agent by applying the blowing agent to the resin component under high temperature and high pressure to remove the pressure and performing foaming. The batch method and the method of crosslinking the resin component with a chemical crosslinking agent or an electron beam, introducing a blowing agent, and heating and foaming can be selected according to the target. In particular, the effect of the present invention is more remarkable in the method for producing an expanded low density foam having a foaming drainage (i.e., foaming ratio) of 5 by extrusion foaming.

Blowing agents which can be used in the preparation of the foams are conventional chemical blowing agents and volatile organic foaming agents. Volatile organic foaming agents are particularly preferred, and blowing agents boiling below the melting point of the thermoplastics under atmospheric pressure may also be used. Representative hydrocarbons include propane, butane, pentane, pentene, hexane, hexene, heptane and octane. Also included are halogenated hydrocarbons with similar limits for boiling points. Examples of halogenated hydrocarbons that can be used include methylene chloride, trichlorofluoromethane, dichlorofluoromethane, chlorodifluoromethane, trifluoromethane, 1, 1'-dichloroethane, 1-chloro-1,1'- Difluoroethane, 1,2-dichlorotetrafluoroethane, clopentafluoroethane and similar halogenated hydrocarbons. Mixtures of these materials are also useful. Chemical blowing agents include azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetraamine and p-toluenesulfonylhydrazide. Mixtures of chemical blowing agents and volatile organic blowing agents described above are also useful.

In addition to the compounds and blowing agents described above, the foaming components contain small amounts of metal salts such as zinc stearate and finely ground inorganic materials such as calcium silicate as lubricants and foaming regulators. Depending on the environment, shrinkage inhibitors, charge inhibitors, stabilizers, colorants, lubricants and the like due to ultraviolet irradiation can be added to 5% by weight or less.

The method of the present invention can be used for various types of foamed products, such as foamed products such as paper, blocks, rods, tubes, wires and sheathed cables.

The following methods and criteria are useful for measuring the purpose of the invention in the practice of the invention.

The effect of the present invention is evaluated based on the shrinkage ratio after foaming and the surface state of the foam after dimensional stabilization.

In the examples, the shrinkage ratio (% by volume) after foaming is calculated as follows.

Shrinkage ratio when “n” days after firing =

The foam used as a test sample for measuring the shrinkage ratio is foamed on a round rod (about 25 mm in diameter and about 50 cm in length). The diameter is measured with slide calipers and the length is measured with steel. The diameter and the area after n days are measured in the same manner based on the volume calculated based on the volume measured immediately after foaming. Calculate the volume and find the shrinkage ratio based on the above formula.

In the following examples the relative evaluation of the surface properties of the foam after dimensional stabilization is as follows:

From an industrial and practical point of view, the shrinkage of the foam should be as small as possible. The shrinkage ratio at the beginning (1 day after foaming) should be less than about 15%. If it is larger than this, recovery to the original size and achievement of dimensional stabilization require a long time (1 month or more), and the quality of the foam surface is also degraded. In addition, the difference between the shrinkage ratio at an early stage and the shrinkage ratio after 10 days should be within about 10%. If it is larger than this, the size cannot be adjusted well, and as a result, the product size changes considerably.

The following operational examples illustrate the invention in detail. All parts and percentages in this example are by weight unless otherwise indicated.

[Mobile Example 1 and Comparative Example 1]

Resin: Ethylene-Vinyl Acetate Copolymer

(D-2021))(Vinyl acetate content: 10%; Density: 0.93 g / cm ³ ; MI = 1.5; Evaate of Sumitomo Chemical

(D-2021))

100 copies

Foam Control Agent: Calcium Stearate 0.1part

Calcium silicate 0.6part

Various components to which the resin and the bubble control agent were added together with the compounds shown in Table 1 were passed through a 40 mm diameter single screw extruder equipped with an extrusion die with a 5 mm diameter hole. Then, they are kneaded together with the volatile organic foaming agent supplied from the separation compressor. At this time, the extrusion foaming is made in the extrusion die.

Compounds A, B, C and D in Table 1 are tri (1-stearyl-glycero-3) borate, tri (1,2-di-stearyl-glycero-3) borate and tri (monopalmityl Polyoxyethylene glycol) borate (m 7 of general formula (I)) and tri (monopalmitylethylene glycol) borate. Blowing agents I, II and III are dichlorodifluoromethane, 1,2-dichlorotetrafluoroethane and butane, respectively.

In the test of Comparative Example 1, the components were foamed in the same manner as in Operation Example 1, but the additives were changed, and the results are summarized in Table 1.

In this comparative example, shrinkage occurs after foaming in all cases. Recovery to the state immediately after foaming does not occur even after the product is left for a long time. The surface of the obtained foam is very uneven and wrinkled and the quality of the product is poor.

In Table 1, additives A ′, A ″, C ′ and D are tri (1-captyl-glycero-3) borate, tri (1-certyl-glycero-3) borate and tri (monopalmitylpoly), respectively. Oxyethylene glycol) borate (m = 20 in formula (I)) and tri (monocapryl ethylene glycol) borate.

1 and 2 show the change in volume and weight of the foam over time of Experiment 1 of Operation Example 1 over Experiment 1 of Comparative Example 1. FIG.

As shown in FIG. 1, when the components of the present invention are foamed, the volume change of the foam over time is extremely small, and an excellent foam is obtained. As shown in FIG. 2, in comparison with the change in weight, the transmission of the blowing agent gas is suppressed by the present invention. In addition, the surface and appearance of the foam of the present invention proved to be excellent.

[Mobile Example 2 and Comparative Example 2]

)을 사용하고, 기포조절제로서 스테아린산 칼슘 0.06부와 규산칼슘 0.36부의 혼합물을 사용한다.Extrusion foaming was carried out under the same conditions as in Operation Example 1 and Comparative Example 1, except that polyethylene (density: 0.919 g / cm ³ ; MI = 2.0; F-1920 of Asahi-Dow) was used as the resin.

) And a mixture of 0.06 parts of calcium stearate and 0.36 parts of calcium silicate is used as the bubble control agent.

The results are shown in Table II.

TABLE I

TABLE II

Operation Example 3

0.3% by weight of dicumyl peroxide as a crosslinking agent and 1.5% by weight of shrinkage inhibitor A1.5 were kneaded and poured into the same polyethylene resin as used in Operation Example 2. The crosslinked polyethylene resin having a gel ratio of 60% (1.2 mm in diameter) was immersed in dichlorodifluoromethane in a pressure vessel under elevated pressure and elevated temperature, and then the product was cooled. The obtained polyethylene foam particles (containing 14% by weight of dichlorodifluoromethane) were foamed by heating in water vapor. (Heating conditions and water vapor pressure 0.23kg / cm ² G, 45 seconds). The first foam particles obtained are uniform foam particles having a density of 90 kg / cm ³ . The obtained foamed particles were first injected into a pressure-resistant container and treated at 80 ° C. for 15 minutes while being pressurized at 10 kg / cm ² G. Foaming through water vapor at a pressure of 0.32 kg / cm ² G gives a second foamed particle having a density of 25 kg / m ³ .

This second foamed particle is compressed at an air pressure of 1.5 kg / cm ² and filled in a metal molded foaming machine (Model ECHO-120, manufactured by Kinjoku Co., Ltd.). The foam is formed by heating at a pressure of 1.2 kg / cm ² G in water vapor. The density of the obtained foam is 31 kg / m ³ . At this time, the fusion between the particles was excellent and the free-foaming property was less than 0.01.

Comparative Example 3

Foamed particles were prepared in the same manner as in Operation Example 3, except that no shrinkage inhibitor A was added. The density of the first obtained particles was 110 kg / m ^3, and the density of the secondly obtained foam particles was 30 kg / m ³ . When these particles were compared with the particles obtained in Operation Example 3, they shrunk in all cases and wrinkled the surface.

The useful life of the foamed particles immersed in the blowing agent according to this comparative example was very short compared to the foamed particles in the operation example 3, the life of the material of the operation example 3 compared to the life of the material of the comparative example is only 20 minutes It was about 6 hours.

Furthermore, when the formed foams were compared with those obtained in Operation Example 3, the free foaming properties were large, and their buffering capacity and mechanical properties were found to be poor.

Operation Example 4

690, MI=8.0) 100중량부에 첨가한 수지조성물을 디클로로디플루오로메탄(F-12) 10.0중량부를 사용하여 가동실시예 1의 방법으로 발포한다.0.5 parts by weight of tri (1-stearyl-glycero-3) borate and talc polystyrene resin (Asahi Dow; styron

690, MI = 8.0) The resin composition added to 100 parts by weight was foamed by the method of Operation Example 1 using 10.0 parts by weight of dichlorodifluoromethane (F-12).

As a result of measuring the weight of the foaming agent in the obtained foam (foam density of 40 kg / m ³ ), it was found to be 9.5 parts by weight / 100 parts by weight of resin.

Comparative Example 4

A foam was prepared in the same manner as in Operation Example 4 except that tri (1-stearyl-glycero-3) borate was not added.

The weight of the blowing agent in the foam (density 40 kg / m ³ ) is 7.4 parts by weight / 100 parts by weight of resin.

Comparing Operation Example 4 and Comparative Example 4, it can be seen that the gas efficiency of the blowing agent is significantly increased by adding a small amount of the compound of the present invention (that is, the compound of formula (I)).

The above described embodiments are illustrative of the present invention and do not limit the scope of the present invention.

Claims (1)

A method for producing a low density, independent foamed synthetic resin foamed product by mixing the resin together with a blowing agent in a thermoplasticized form under elevated pressure and sending the resulting mixture at a low temperature and low pressure, wherein the resin is used before being sent to the low temperature and low pressure. An improved production method characterized by incorporating 1.0 to 10% by weight of the glycol ester compound of the following general formula (I) into the mixture of the thermoplastic resin / foaming agent based on the amount.

In the above general formula, R ₁ is an aliphatic hydrocarbon radical having 10 to 24 carbon atoms, R ₂ is an aliphatic polyhydric alcohol resin residue having 1 to 5 carbon atoms, and ℓ is greater than 1 and [(an alcohol atom of the R ₂ group) -1 Is a positive number less than], m is a positive number greater than 1 that satisfies

n is a positive number of 1 to 3, M is boric acid or phosphate residues.

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