KR840001712B1 - Forming synthetie resin compositions - Google Patents

Abstract

A foamable synthetic resin compsn. is composed of a solid-state aliphatic olefin polymer, a volatile organic foaming agent, and 0.1-10 wt.% (based on olefin polymer) of one or more compds. of formula R1-X-R2. R1 and R2 are C3-24 hydrocarbon, either one of them being) C10 X is -C(=0)-o-, -C(=0)-S-, -C(=0)-o-C(=0)-, -S-, or -o-.

Description

Expandable synthetic resin compositions stabilized with higher ethers, esters or anhydrides

FIG. 1 is the percent change in foam volume over time based on the initial foam volume of the foam sample resulting from Formulation 1 of Example 1 and Form 1 of Reference Experiment 1. FIG.

FIG. 2 is the percent change in foam weight over time based on the initial foam weight of the foam sample resulting from Formulation 1 of Example 1 and Form 1 of Reference Experiment 1. FIG.

The present invention relates to a foamable synthetic resin composition comprising at least one compound (0.1 to 10% by weight based on the aliphatic olefin polymer) for suppressing the release of the blowing agent gas from the aliphatic olefin polymer, the blowing agent and the expanded foam. Gas efficiency is improved and shrinkage of the expanded foam is significantly reduced.

It is generally known to produce a resin foam by adding a foam foaming agent to a thermoplastic synthetic resin and heating the resulting resin / foaming agent mixture to gasify the foaming agent to expand the resin. This efficiency improvement of the blowing agent is important for the commercial scale mass production of synthetic thermoplastic foams.

Among thermoplastic resins, in particular aliphatic olefin polymers are difficult to directly expand into commercial scale manufacturing processes. This is because their thermodynamic viscoelasticity in the molten state is highly temperature dependent and the permeability of the blowing agent gas to the foam cell membrane is high. Another problem is the latent heat of crystallization and thermal expansion that can occur during the foaming of such aliphatic olefin polymers. The aliphatic olefin polymers are mixed or crosslinked with other resins and modified before expansion to bring the expansion rate to 5 or more.

In contrast, Japanese Patent Publication No. 35 (1960) -4341 discloses an extrusion-foaming process of a non-crosslinked polyolefin using a relatively expensive blowing agent such as 1,2-dichlorotetrafluoroethane. The resulting foam product, however, sometimes shrinks gradually and changes in density, resulting in a corrugated appearance. Therefore, it is desirable to improve the quality and dimensional control of foams produced by such processes.

Recently, several chemical additives have been discovered that improve the quality of the olefin polymer foam and improve the dimensional stability without cross-linking and / or resin blending techniques, and have been somewhat valued instead of 1,2-dichlorotetrafluoroethane. Inexpensive volatile organic foaming agents can be used. Such additives include saturated higher fatty acid amides, saturated higher fatty acid amines, and complete esters of saturated fatty acids (see Wadanabe et al., US Pat. No. 4,214,054), partial esters of long chain fatty acids (Cronine, US Pat. No. 3,644,230, and renfreund). , US Pat. Nos. 3,755,208), partial and complete esters of aliphatic fatty acids (see Komori, US Pat. No. 4,217,319 and related Japanese Laid-Open Patent Publications 53-102971, 54-34374, and 54-39476).

The present invention provides chemical additives that improve the dimensional stability of aliphatic olefin polymer foams. In particular, the present invention provides an olefin polymer composition consisting of a generally solid aliphatic olefin polymer that is readily expanded by using commercially available inexpensive blowing agents, resulting in a foam product with reduced shrinkage and improved dimensional stability and surface. do.

According to the present invention, the expandable olefin polymer composition consists of an aliphatic olefin polymer, a volatile organic foaming agent and a compound of general formula (I) of 0.1% to 10% by weight, based on the olefin polymer.

R ₁ -XR ₂ (I)

In the above general formula

R ₁ and R ₂ each represent an aliphatic hydrocarbon group having 3 to 24 carbon atoms, at least one of which is 10 or more carbon atoms,

중에서 선택된 기를 나타낸다.

The group selected from among these is shown.

The expandable aliphatic olefin polymer compositions of the present invention are particularly advantageous in that high quality foam products with increased dimensional stability are obtained even with comparatively bonded olefin polymers and relatively cheap volatile organic blowing agents. The use of these new types of additives, stabilizers, gives greater flexibility to the foam production process.

FIG. 1 is a chart showing the change in volume over time of the foam generated from Formulation 1 of Example 1 and Formulation 1 of Reference Example 1 in percent based on the original foam volume.

FIG. 2 is a plot of the change in weight over time of the foam resulting from the same formulation in percent based on the original foam weight.

Suitable stabilizers for use in the present invention are compounds of formula (I).

R ₁ -XR ₂ (I)

Wherein R ₁ and R ₂ each represent an aliphatic hydrocarbon group having 3 to 24 carbon atoms, at least one of which has 10 or more carbon atoms.

Examples of compounds which provide such hydrocarbon groups are butyric acid, isobutyric acid, caproic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, arachic acid, Alcohols obtained by reduction of henic acid, erucic acid and diacids by known methods, acid anhydrides obtained by dehydration of thiols and esters, thioesters, ethers, thioethers.

These compounds may be mixtures of fatty acids and derivatives thereof produced from natural fats or oils. Some of these compounds may be replaced by compounds containing unsaturated aliphatic hydrocarbon groups.

As mentioned earlier, at least one of R ₁ and R ₂ must be an aliphatic hydrocarbon group having 10 or more carbon atoms. If both R ₁ and R ₂ are less than or equal to 9 carbon atoms, the advantageous results of the present invention are not obtained because the compounds do not provide the necessary combination of binding strength and solubility to the aliphatic olefin polymers used.

Examples of the compound represented by the general formula (I) include undecanoic anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, behenic anhydride, caprodecanoic anhydride, and capr As well as stearic anhydride, stearoolthenic anhydride, beheneulux anhydride, diundecyl ether, dimyristyl ether, dipalmityl ether, distearyl ether, caprylcearyl ether and thioether corresponding to this ether, Decanundecanoate, undecane laurate, dodecane myrilate, stearyl stearate, stearyl oleate, stearyl behenate docoic acid erugate, thioesters corresponding to this ester, and the like.

According to the present invention, the expandable resin composition should contain at least 0.1% by weight of at least one compound of the general formula (I) based on the aliphatic olefin polymer, and when the two or more compounds are used, the total content should be 0.1% to 10% by weight. .

The amount of the compound of formula (I) is determined within this range depending on the form of the desired foam, the physical and mechanical properties as well as the type of blowing agent and polymer used. Generally, the total amount is preferably 0.3% to 7% by weight. If the content of the compound of formula (I) is less than 0.1% by weight, the resulting foam is of poor quality. On the contrary, even if more than 10% by weight, no further improvement will be made and an undesirable plasticizing effect will occur.

The aliphatic olefin polymers mentioned here are low density polyethylene, medium density polyethylene, high density polyethylene, isotactic polypropylene and poly-1-butene and propylene with (1-octene) -ethylene copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate Copolymers of ethylene or propylene such as copolymers, ethylene-acrylic acid copolymers, ethylene-ethylacrylate copolymers, ethylene-vinylchloride copolymers with other monomers that may be copolymerized therewith, zinc, sodium of ethylene-acrylic acid copolymers And magnesium salts, usually solid polymers consisting mainly of olefins. These polyolefin resins can be used individually or in mixtures of two or more.

In mixing the compound of formula (I) of the present invention with an aliphatic olefin polymer, such components may be mixed and kneaded by any suitable conventional method such as a single-screw extruder, a twin-screw extruder, a compound roller and a Banbury mixer. . Preliminary mixtures of compounds of formula (I) and olefin polymers may be prepared as dry mixtures or master batches, or compounds of formula (I) may be mixed just prior to expansion with the polymer in a molten or thermoplasticized state.

The expandable olefin polymer composition of the present invention can be expanded into a foam in a conventional manner. For example, conventional extrusion foaming techniques heat a mixture of an olefin polymer and a compound of formula (I) of the present invention to melt or thermoplasticize and add volatile organic blowing agents at elevated temperatures at elevated pressures. The resulting molten or thermoplastic mixture is then extruded to low pressure to produce a foam. Alternatively, a batch process may be employed in which the olefin polymer composition is added to the molten olefin polymer composition at elevated temperature under elevated pressure and then pressure is removed from the molten mixture. The compound of formula (I) olefin may also be crosslinked, if necessary, with an electron beam or chemical crosslinker before expansion. However, the present invention is particularly effective when applied to extrusion-expansion of olefin polymer compositions, in particular when inflating these mixtures to five times or more of their original volume before expansion.

Any conventional volatile organic blowing agent can be used. However, particularly effective in the present invention are volatile organic foaming agents having lower boiling points than the melting points of the aliphatic olefin polymers used. Representative examples of such effective blowing agents are propane, butane, pentane, pentene, hexane, hexene, heptane, octane and the like. Also used as blowing agents are methylene chloride, thiochlorofluoromethane, dichlorofluoromethane, chlorodifluoromethane, chlorotrifluoromethane, dichlorodifluoromethane, 1,1-dichloroethane, 1- Halogenated hydrocarbons having the aforementioned conditions with respect to boiling points such as chloro-1, 1-difluoroethane, 1,8-dichlorotetrafluoroethane, croropentafluoroethane and mixtures thereof and the like. In addition to such volatile organic blowing agents, known chemical blowing agents such as azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetraamine, p-toluenesulfonyl hydrazide can be used together with such volatile organic blowing agents.

The foamable olefin polymer compositions according to the present invention may comprise small amounts of zinc stearate or similar metal salts and lubricants such as finely divided calcium silicates or inorganics and nucleating agents. In addition, the resin composition of the present invention may contain a UV absorber, an antistatic agent, a stabilizer, a colorant and / or a lubricant, wherein the total amount thereof should not exceed 5% by weight.

The expandable aliphatic olefin polymer compositions of the present invention can be expanded to almost any form, such as sheets, blocks, shelves, pipes, or can be used for applications such as sheathing or designing wires or cables and for various other foam products.

The invention is better illustrated by the following examples and comparative examples (reference experiments). The resulting foam product is evaluated as shrinkage after expansion (ie shrinkage over time after expansion) and as the surface state of the foam after dimensional stabilization. All parts and percentages are by weight unless otherwise indicated.

Shrinkage after expansion (percent relative to initial expansion volume) is measured using a round foam rod test sample (diameter 25 mm, length 50 cm) obtained by extruding the olefin polymer composition. Immediately after foaming and after n days, the diameter and length of each sample were measured with a vernier measuring instrument (JIS Class 1) and a steel ruler (JIS Class 1) to determine the volume. Their post-expansion shrinkage is calculated by the formula:

Shrinkage after n Days of Expansion

The surface state of various test samples is evaluated by the following three relative grades.

For industrial use, it is desirable to minimize the shrinkage of the foam after expansion. In general, the initial contraction (shrinkage rate within one day after expansion) should be less than 15%. If the initial shrinkage exceeds this rate, it will take much longer (about 1 month) to restore the original dimensions, and the foam will generally have excessive wrinkles on the surface. Furthermore, the difference between the initial shrinkage rate and the shrinkage rate after 10 days of expansion is preferably 10% or less. If the shrinkage difference exceeds this level, the deviation of the dimensions of the resulting foam product becomes undesirably large.

Example 1 and Reference Example 1

Base resin: Ethylene-vinyl acetate copolymer (containing 10% vinyl acetate, density 0.93% cm 3 and MI is

The base resin and nucleating agent components, together with each component in the following Table 1, are fed to a single-screw extruder with a barrel diameter of 40 mm, equipped with a die with a round diameter of 5 mm in diameter. The resulting resin composition is melted and kneaded with a separately supplied volatile blowing agent (see Table 1) and then the melt mixture is extruded through the die into the atmosphere to expand into a foam.

Additives A, B, C, D and E in Table 1 are behenic anhydride, distearyl ether, distearyl thioether, stearyllaurate and stearyl thilaurate, respectively. Dichlorodifluoromethane and 1,2-dichlorotetrafluoroethane were used as blowing agents I and II, respectively.

In Reference Example 1, the same procedures and conditions as in Example 1 were used and no additives were used or other additives A ', A ", C' or D 'instead of additives A, B, C, D and E were used. Additives A ', A ", C' and D 'are ethyl stearate, stearylpropioate, stearylmethyl ether and nonan carbonate, respectively.

The experimental results of Example 1 and Reference Experiment 1 are summarized in Table 1.

As a result of all the experiments in Reference Example 1, the resulting foam exhibited significant post-expansion shrinkage, most of which remained intact for a long time. They also have numerous wrinkles on the surface and irregular surfaces.

FIG. 1 and FIG. 2 show that the volume and weight of the foam sample according to Form 1 of Example 1 and Form 1 of Reference Experiment 1 change over time. As apparent from FIG. 1, the foam prepared by extruding the resin composition of the present invention hardly changed in volume over time. According to FIG. 2 showing the change in weight of the foam sample according to Form 1 of Example 1 and Reference Experiment 1 according to FIG. 2, the foam of Formulation 1 of Example 1 was formed at a higher time than the foam of Form 1 of Reference Experiment 1. The weight loss is small. From this, it can be seen that in the foam prepared by expanding the resin composition of the present invention, the degree of blowing of the blowing agent gas through the cell wall is significantly reduced. Furthermore, the gas permeability through the cell walls is reduced, thereby reducing the changes in the volume and weight of the foam and improving the appearance of the resulting foam surface.

TABLE 1

* Not an embodiment of the invention

Example 2 and Reference Example 2

을 사용하고 핵생성제성분, 즉 칼슘 스테아레이트 및 칼슘 실리케이트 성분을 각각 0.06부 및 0.36부로 변경시킨 이외에는 실시예 1 및 참조실시예 1과 같이 조작을 반복한다. 실험결과는 표 2에 요약하였으며 여기서 발포제 I 및 Ⅲ은 각각 디크로로디플루오로메탄과 부탄이다.Example 1 and Reference Example 1 are F-1920 produced by Ashai-Dow LTD with 100 parts of polyethylene (density 0.919 g / cm 3 and MI 2.0 as base resin instead of ethylene-vinylacetate copolymer).

The procedure is repeated as in Example 1 and Reference Example 1 except that the nucleating agent component, that is, calcium stearate and calcium silicate component is changed to 0.06 part and 0.36 part, respectively. The experimental results are summarized in Table 2, where blowing agents I and III are dichlorodifluoromethane and butane, respectively.

TABLE 2

* Not an embodiment of the invention

Example 3

The same polyethylene resin as used in Example 2 was mixed and kneaded with 0.3 percent dicumyl peroxide as a crosslinking agent and 2.5 percent behenic anhydride as a water resistant agent to obtain a crosslinked polyethylene resin having a gel ratio of about 60% ( As a granular material having an average diameter of about 1.2 mm). The granular material is impregnated with dichlorodifluoromethane in a pressure vessel at atmospheric pressure and then cooled to prepare an expandable crosslinked polyethylene granular material containing 14 percent of dichlorodifluoromethane. This expandable particulate material is expanded by heating with 0.23 kg / cm 2 G (22.6 kPa) steam for 45 seconds. The primary expanded granular material thus obtained has an almost uniform density distribution of about 90 kg / m 3. Thereafter, the first expanded granular material was heated in a pressure vessel at 80 ° C. for 15 hours while being pressurized with 10 kg / cm 2 G (981 kPa) of compressed air. Subsequently, a secondary expanded granular material having a density of 25 kg / m 3 was prepared by blowing 0.32 kg / cm 2 G (31.4. KPa) steam into the granular material.

The obtained secondary expanded granular material was compressed into 1.5 kg / cm 2 G (147 kPa) compressed air, and charged into a compression molding machine (ECHO-120 type manufactured by Toyo Machinery & Metal Co., Ltd.) and 1.2 kg / A molded product is manufactured by heating with cm 2 (118 kPa) steam. The density of the molded product is 31kg / ㎥ and the melting state between the granular materials is excellent.

Subsequently, a 100mm × 100mm × 25mm product piece was made and the product piece was immersed in water in a vacuum chamber (the upper part of the test piece was present at about 5cm below the water surface), and the pressure inside the chamber was reduced to 460mmHg (absolute pressure). The water absorption of the molded foam product obtained by accurately measuring the volume (V) and weight (W ₀ ) of the test piece by standing in water for 10 minutes is measured. Subsequently, the chamber internal pressure is reduced to atmospheric pressure, the test piece is taken out and soaked in methanol having a purity of 95% or more for 2 seconds. The treated specimens were then air dried at 60 ° C. for 5 minutes to accurately re-weigh the specimen weights (W ₁ ) and obtain moisture absorption from the measurements W ₀ , W ₁ and V by the following formula.

The moisture absorption rate obtained in the above formula indicates the closed cell characteristics of the foam test piece, and the fact that the water absorption rate is low (that is, a relatively small amount of water is absorbed into the sample) means that most of the foam test pieces are closed pores. That is, almost no open cells).

The water absorption of the molded foam article mentioned in this particular example is 0.01 g / cm 3 or less.

[Reference Experiment 3]

The first and second expanded granular materials were prepared under the same conditions and preparations as those used in Example 3 except that no additive of behenic anhydride was used. The density was 110 kg / m 3 and 30 kg / m 3, respectively. These primary and secondary expandable particulates exhibited significant shrinkage as compared to the product obtained in Example 3 so that the surface was full of wrinkles.

In addition, the expandable particulate material of Reference Experiment 3, deposited with a blowing agent, was only 20 minutes shorter in service life than can be observed in Example 3.

In addition, the molded article obtained in Reference Experiment 3 had a high water absorption rate (0.015 g / cm 3) compared with Example 3, and its impact canceling and mechanical properties were significantly inferior to those of Example 3.

Claims (1)

A synthetic resin composition composed of 0.1 to 10% by weight of at least one compound of the following general formula (I), based on an aliphatic olefin polymer, a volatile organic foaming agent and an olefin polymer, which are usually in the solid state. R ₁ -XR ₂ (I) In the above formula R ₁ and R ₂ each represent an aliphatic hydrocarbon having 3 to 24 carbon atoms, at least one of which has 10 or more carbon atoms,

It is a group selected from.

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