GB2107326A - Soft thermoplastic resin and its production and use - Google Patents

Abstract

A soft thermoplastic resin is produced by polymerizing vinyl chloride or a mixture consisting of vinyl chloride and a monomer which is copolymerizable therewith and gives a homopolymer having a glass transition temperature of less than 30 DEG C, in the presence of a water medium, a suspending agent and an oil-soluble polymerization initiator and in the presence of a thermoplastic polyurethane elastomer soluble in the monomeric vinyl chloride and having a softening point of 20 DEG C to 100 DEG C in a proportion of 10 to 200 parts by weight per 100 parts by weight of the monomer or monomer mixture. Said thermoplastic resin can be suitably used in the manufacture of medical appliances, a surface protection coating of optical fiber cables, a coating of electrical wire, a laminate, a wrapping film and a flexible hose.

Description

SPECIFICATION Soft thermoplastic resin and its production and use This invention relates to thermoplastic resins and their production and uses.

Various processes have hitherto been proposed for producing internally plasticized resin of polyvinyl chloride type. Examples of these processes including a process in which MVC is graftcopolymerized on an ethylene/vinyl acetate copolymer, an ethylene/acrylate copolymer, an ethylene/propylene copolymer or the like and a process in which MVC and an acrylate are copolymerized. Copolymers obtained from these processes are internally plasticized and have a flexibility in the umplasticized state; however they are unsatisfactory in moldability, heat resistance, oil resistance and transparency. Therefore, their applications are limited.

The present invention provides a process for producing soft thermoplastic resin comprising polymerizing 100 parts by weight of monomeric vinyl chloride (hereinafter abbreviated as MVC) or a monomer mixture consisting of MVC and a monomer copolymerizable with MVC and giving a homopolymer having a glass transition temperature of less than 300C (hereinafter, MVC and the said monomer mixture are collectively referred to as MVC-type monomer) in the presence of 10 to 200 parts by weight of a thermoplastic polyurethane elastomer soluble in MVC and having a softening point of 200 to 1 000C (hereinafter abbreviated as MVC-soluble TPU) and also in the presence of an aqueous medium, a suspending agent and an oil-soluble polymerization initiator.

The present invention also provides resins obtained by the process.

By proceeding in accordance with the present invention it is possible to obtain a soft thermoplastic resin having a flexibility in the unplasticized state and that is superior in moldability, heat resistance, oil resistance, low-temperature resistance and transparency.

The resins obtained can be used in the manufacture of medical appliances, in surface protection coating of optical fiber cables, as coating for electrical wires, as a laminate, as a wrapping film and in a flexible hose.

More specifically, the soft thermoplastic resin of the invention is produced by polymerizing the MVC type monomer in the state that the MVC-soluble TPU is dissolved in the MVC type monomer. The mechanism of this reaction is not clarified but it is inferred that there occurs a certain chemical bonding (so-called graft copolymerization) between the MVC-soluble TPU and the MVC type monomer. This is based on the fact that the polymer obtained by the process of this invention is signifiantly improved, that is, superior in moldability, transparency, flexibility and so forth, as compared with a polymer blend of the same TPU and PVC.

The MVC-soluble TPU in this invention must be substantially soluble in the MVC type monomer under the polymerization conditions under which the process of this invention is carried out, and also must have a softening point of 1000 to 200C, preferably 600 to 300C. The softening point used herein means the softening point determined according to a temperature-gradually-increasing method by means of a Shimazu Koka flow tester under the following conditions: Size of nozzle: 1 mmf x 2 mmL Load: 30 kg Temperature-increasing rate: 30C/min When the softening point exceeds 1 000C, the TPU is difficult to dissolve in the MVC type monomer.

When the softening point is less than 20"C, the polymer product obtained is inferior in tensile strength, heat resistance and oil resistance. As the MVC-soluble TPU, a non-yellowing type TPU in which an aliphatic diisocyanate is used as the raw material is preferable.

In general, the thermoplastic polyurethane elastomer refers to an elastomer having a urethan linkage in the structure, and is a linear block copolymer consisting of a linear polyurethane as a soft segment (long chain polyol), which is usually formed by reacting a diisocyanate with a polymer diol having OH groups at both ends, and a linear polyurethane as a hard segment (including short chain polyol, crosslinking agent, and chain-extender), which is formed by reacting a glycol or diamine with a diisocyanate. The thermoplastic polyurethane elastomer used in this invention is required to be soluble in MVC and have a softening point of 200 to 1 000C. It is necessary to determine the soft segment and the hard segment so as to meet these requirements.When the hard segment (chain extender) is too much, the molecular weight becomes too large, the solubility becomes unsatisfactory and the elastomer becomes too hard and has a softening point of more than 1 000C. Therefore, the amount of the hard segment should be controlied so that the softening point does not exceed 1 000C. In this invention, therefore, it is preferable for the thermoplastic polyurethane elastomer to be composed mainly of the soft segment, and the hard segment may, if necessary, be contained in a very small amount.

As the polymer diol constituting the soft segment of the thermoplastic polyurethane elastomer, there may be used polyester diol, polyether diol, polyolefin diol, polyactone diol and the like, and the average molecular weight of these polymer diols are preferably 500 to 10,000.

As the polyester diol, there may be used esterification products of dicarboxylic acids, such as glutaric acid, adipic acid, succinic acid, suberic acid, sebacic acid, oxalic acid, methyladipic acid, pimelic acid, azelaic acid, phthalic acid, terephthalEc acid, isophthalic acid, maleic acid, fumaric acid, and the like, with diols such as ethylene glycol, 1 ,4-butane diol, 1 ,6-hexane diol, propylene glycol, diethyiene glycol, neopentyl glycol and the like.

As the polyether diols, there may be used polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like.

As the polyolefin diols, there may be used polybutadiene diol, and the like, and as the polylactone diol, there may be used poly--caprolactone diol and the like.

In this invention, it is preferable to use a thermoplastic polyurethane elastomer comprising the polyester diol, and particularly preferable to use an adipic acid type polyester because the properties of the soft thermoplastic resin obtained are excellent.

As the glycol and diamine constituting the hard segment, there may be used the diols mentioned above as the ingredients of the polyester diols; aliphatic and aromatic diamines such as ethylene diamine, propylene diamine, xylene diamine and the like.

The diisocyanate used for the soft segment and the hard segment, may be selected from 4,4'diphenylmethane diisocyanate, 4,4'-diphenyl isocyante, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylene diisocyanate, tetramethylene diisocyanate.

pentamethylene diisocyanate, hexamethylene diisocyanate and the like and mixtures of two or more of them.

The thermoplastic polyurethane elastomer used in this invention is preferably of non-yellowing type as mentioned above, and therefore, as the diisocyanate, there may be preferably used aliphatic diisocyanates, such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate and the like.

The thermoplastic polyurethane elastomer used in this invention has the above-mentioned constituents and it is essentially necessary for the elastomer to be dissolved in MVC in order to obtain the objective soft thermoplstic resin of the invention. The thermoplastic polyurethane elastomer soluble in MVC has a weight average molecular weight of about 1 80,000 or less as measured by GPC, and the viscosity of a 20% methyl ethyl ketone solution (referred to hereinafter as 20% MEK viscosity) of the resin is about 2,000 cps or less as measured by means of a Vismetron type rotation viscometer (No. 3 rotor, 60 r.p.m., 60 sec). The term "20 v6 MEK viscosity" is used herein in this sense.

In this invention, a thermoplastic polyurethane elastomer having a high viscosity requires a long time to dissolve in MVC, and one having a low viscosity brings about a soft thermoplastic resin inferior in properties. Therefore, the viscosity is preferably 301,000 cps, more preferably 50-400 cps, most preferably 100--300 cps.

The non-yellowing type TPU is good in ultra-violet stability, while other type TPU's have a tendency to be coloured after the polymerization. As MVC-soluble TPU's effective in this invention, there may be used, for instance, Pandex T-5265 (a polyurethane composed mainly of an adipate and an aliphatic diisocyanate and having softening point: 530C; 20% MEK viscosity: 800 cps; molecular weight: 119,782), PandexT-5265L (a polyurethane composed mainly of an adipate and an aliphatic diisocyanate having a softening point of 400C, a 20% MEK viscosity of 260 cps, and a molecular weight of 96,126), Pandex T-5265LL (a polyurethane composed mainly of an adipate and an aliphatic diisocyanate having a softening point of 450C, a 20% MEK viscosity of 100 cps and a molecular weight of 79,240), and PandexT-525 (softening point:470C) (these are trade names of Dainippon Ink And Chemicals, Inc.).

In this invention, the polymerization is initiated in the presence of the MVC-soluble TPU in a quantity of 10 to 200 parts by weight, preferably 2Q to 1 50 parts by weight, per 100 parts by weight of the MVC type monomer.

When the MVC-soluble TPU is used in a quantity of less than 10 parts by weight per 100 parts by weight of the MVC type monomer, the polymer obtained has no satisfactory softness. When the TPU is added in a quantity of more than 200 parts by weight, the rate of polymerization is low, which is not desirable In the present invention, the content of the MVC-soluble TPU in the polymer produced is preferably 10 to 80% by weight, more preferably 1 7 to 65% by weight. When it is less than 10% by weight, it is difficult to obtain a satisfactory softness. When the content is more than 80% by weight, the heat resistance tends to be inferior and the manufacturing cost of the polymer rises. Therefore, said amount is not desirable in economization.

In this invention, as the monomers which are copolymerizable with MVC and give homopolymers having glass transition temperatures of less than 300 C, there may be used olefins such as ethylene, propylene and the like, vinylidene halides such as vinylidene chloride, and the like; vinyl esters of saturated carboxylic acids such as vinyl acetate, and the like; alkyl vinyl ethers such as n-butyl vinyl ether and the like; alkyl acrylates such as butyl acrylate, 2-ethylhexyl acrylate and the like; alkyl methacrylates such as 2-ethylhexyl methacrylate, and the like. These monomers may be used alone or in admixture of two or more.

The content of these monomers in the MVC type monomer is preferably 50% by weight or less, more preferably 30% by weight or less. When it exceeds 50% by weight, the polymer obtained is inferior in moldability, heat resistance, oil resistance, transparency, etc.

As the suspending agent used in this invention, any known suspending agents may be used. For instance, there may be used partially saponified polyvinyl alcohols, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, polyacrylic acids, vinyl ether/maleic anhydride copolymers, gelatin and calcium phosphate. These may be used alone or in combination.

These suspending agents are used in about 0.01 to 2% by weight based on the weight of the water medium.

The oil-soluble polymerization initiator used in this invention may be any known polymerization initiator. For instance, there may be used azo compounds such as azo-bisisobutylvaleronitrile and the like; and organic peroxides such as lauryl peroxide, di-2-ethylhexylperoxy dicarbonate, t-butylperoxy pivalate and the like. The oil-soluble polymerization initiator is used in a quantity of about 0.01 to 2% by weight based on the weight of the MVC type monomer charged.

In this invention, the ratio of the water medium to the MVC-soluble TPU plus the MVC type monomer is preferably from 1/1 to 3/1. When the ratio is less than 1/1 , the polymerization tends to become unstable. The ratio of more than 3/1 is economically disadvantageous.

The polymerization temperature is 300 to 700C, preferably 400 to 600C. When the temperature is less than 300 C, the rate of polymerization tends to be low, which is not advantageous from the industrial standpoint. When the temperature exceeds 700C, the polymer obtained is inferior in heat resistance, which is not desirable.

In this invention, there may be further added a known chain transfer agent such as trichloroethylene, mercaptoethyl alcohol, or the like.

To the soft thermoplastic resin of this invention, there may be added additives conventionally used in the field of PVC processing such as, stabilizers; fillers, for example, calcium carbonate, basic magnesium carbonate, magnesium hydroxide, hydrotalcite, magnesium oxide, sodium hydrogencarbonate, and aluminum hydroxide; flame retardants, for example, antimony trioxide, molybdenum oxide, zirconium oxide, and ferrocene; and pigments. In order to produce a flame-resistant resin, it is preferably to use 1 to 50 parts by weight of the flame retardant and 5 to 100 parts by weight of the filler per 1 00 parts by weight of the soft thermoplastic resin.

In the present invention, when stabilizers are added to the soft thermoplastic resin to improve its heat-aging characteristics and the resin is intended to be used in medical appliances, toxic stabilizers such as lead- or cadmium-based stabilizers must not be added. Stabilizers which may be added for this purpose are calcium stearate and zinc stearate. Besides, a small quantity of epoxidized soybean oil may also be added.

The soft thermoplastic resin of this invention may also be blended with a diene type polymer and polymerizable unsaturated compound having at least two double bonds in the molecule, such as poly(meth)acrylates, for example, ethylene glycol di(meth)acrylate or the like; polyester poly(meth)acrylates; epoxy poly(meth)acrylates; and polyurethane poly(methyl)acrylates, to prepare a thermoplastic resin having a rubbery elasticity.

According to the process of this invention, a soft thermoplastic resin can easiiy be obtained which possesses a flexibility in the unplasticized state is superior in moldability, heat resistance, lowtemperature resistance, water resistance, oil resistance, chemical resistance, weather resistance, transparency, etc., and furthermore is non-toxic.

By utiiizing its properties, the soft thermoplastic resin obtained from the process of this invention can be used in a variety of application fields. It can be suitably used particularly in the production of medical appliances such as, for instance, blood transfusion set, infusion set, circuit for artificial kidney, rectal catheter and gastrotube; surface protection coatings of optical fiber cables; coatings of electrical wires; laminates; wrapping films; and flexible hoses.

From their application requirements, medical appliances, which are representatives of the applications need to be flexible and transparent, possess heat resistance sufficient to withstand sterilization by high pressure steam and be easily molded by heat bonding or other means. Conventional DOP-containing soft polyvinyl chloride resins have been used for the above appliances as a material satisfying the above requirements. However, these resins have a problem of DOP elution and hardening.

DOP has been used in many countries as a non-toxic compound. Recently, however, it has been pointed out that DOP is e!uted from blood appliances such as blood bag by the action of blood, and the influence of eluted DOP on humans when circulated in a human body is now an issue to be clarified. However, the soft thermoplastic resin according to this invention satisfies the requirements of flexibility, transparency, heat resistance sufficient to withstand sterilization by high pressure steam, heat bonding and so forth, and is completely free from problems associated with DOP.

The novel, soft thermoplastic resin according to this invention has a flexibility in the unplasticized state, and is superior in moldability, transparency, heat resistance and heat bonding. Accordingly, this soft thermoplastic resin is molded into medical appliances such as catheter, blood transfusion set and infusion transfusion set. These appliances can be safely put in direct contact with the human body or the liquids to be tranfused into the interior of the body such as infusion, and are extremely useful from the practical purpose.

As highly flame-retarding, inexpensive and flexible coating materials for surface protection of optical fiber cables, the substitution of soft polyvinyl chloride resins containing plasticizers for nylon and polyethylene is now under research by those skilled in the art. If these soft polyvinyl chloride resins are used for the above purpose, namely as surface protection coating materials, plasticizers will migrate into the undercoating and further even into the optical fiber per se, whereby the optical transmission loss will be increased.

Having flexibility in the unplasticized state and being superior in flame retardancy, heat resistance, low-temperature resistance and weather resistance, the novel, soft thermoplastic resin according to this invention is suitable as a coating material for surface protection of optical fiber cables requiring particularly flame retardancy.

The soft thermoplastic resin of this invention can also be used for coating electrical wires by the use of processing methods being used in the field of PVC processing such as an extrusion coating method and an injection method.

Hitherto, polyvinyl chloride resin containing a large amount of a plasticizer has been used in said field because polyvinyl chloride resin is characterized by containing chlorine and hence having a low flammability, and further having excellent mechanical properties. However, the plasticizer-containing polyvinyl chloride has various problems due to the plasticizer contained. These problems have been solved by using the soft thermoplastic resin of this invention.

The novel, soft thermoplastic resin of this invention is suitable as a material for flexible hoses.

Flexible hoses produced by processing this resin is very useful industrially. For instance, in hoses for brewage produced from conventional soft PVC's, namely plasticizer-containing PVC's, plasticizers are extracted by the alcohol in beverages, which is undesirable from the sanitary standpoint. Also, the use of these hoses over along period of time is impossible due to stiffening of hoses and deterioration of mechanical properties, etc. Such problems can be solved by the use of the soft thermoplastic resin of this invention.

When the soft thermoplastic resin of this invention is used for manufacture of hoses for washing machines, these hoses can withstand use for a long period of time because there is no extraction of plasticizer by aqueous soap solution.

The soft thermoplastic resin of this invention can be used as one layer of laminates. As a sheetshaped substrate which is the other element, there are used paper, knitted fabric, woven fabric, nonwoven fabric, etc. Generally, a fabric backing such a woven fabric or knitted fabric is used. There are various kinds of fabric backings such as plain weave fabrics (shirting, havy shirting, canvas, duck, victoria lawn, etc.), twill fabrics (jeans, drill, three-leaf twill, gaberdine, etc.), fancy fabrics (satin, crepe weave, etc.), knitted fabrics (interlock fabric, millanese fabric, tricot fabric, etc.) and nonwoven fabrics.

These fabric backings can be selected depending upon their applications and characteristics.

As fibers for fabric backings, there may be used cotton; staple fiber, viscose rayon or their mixed fiber; synthetic fibers such as nylon, vinylon and polyester; mineral fibers such as asbestos and glass fiber; and so forth.

The thickness of the fabric backing or sheet-shaped substrate is preferably 0.1 to 2 mm.

The thickness of the above described soft thermoplastic resin formed on the fabric backing or sheet-shaped substrate as mentioned above is preferably 0.05 to 1 mm. The ratio of thicknesses of respective layers is desirably 1/10 to 10/1.

The structure of the laminate may be such that layers of the soft thermoplastic resin are formed on both sides of the fabric backing or sheet-shaped substrate, or such that a layer of the soft thermoplastic resin is formed only on one side of the fabric backing or sheet-shaped substrate.

Lamination is carried out by calendering processing or by heating under pressure. For instance, it can be conducted by pressing the assembly with a press having a heating mechanism or by pressing the heated assembly with a pressing having no heating mechanism. Besides, a press roll, a pressure belt or other appropriate means can be used.

Characteristics of the novel, soft thermoplastic resin of this invention, having a flexibility in the unplasticized state and being superior in moldability, weather resistance, non-migration, transparency, low-temperature resistance, heat resistance and heat bonding are sufficiently exhibited also in the laminate.

Accordingly, the laminate containing the layer of the soft thermoplastic resin of this invention is superior in low-temperature resistance, heat resistance, weather resistance, oil resistance, etc., and can be utilized in chemical industry, food industry and so forth, for instance, as tarpauline, leathers, etc.

By processing the soft thermoplastic resin of this invention into thin films, there can be produced wrapping films (that is, a food wrapping film for home use, a film for covering dishes to be delivered and a film for stretch wrapping). These wrapping films do not contaminate foods. Furthermore, the films have adequate tackiness, whereby their workability in wrapping is superior.

Referring to Examples and Comparative Examples, this invention will be explained more specifically. However, this invention should not be interpreted to be restricted to the Examples.

Evaluations of physical properties in the Examples and Comparative Examples were conducted in accordance with the following manner, and in the Examples and Comparative Examples, all parts are by weight unless otherwise specified.

One hundred parts of the polymer obtained was mixed with 3 parts of epoxidized soybean oil, 1 part of barioum stearate and 1 part of zinc stearate, and the mixture was kneaded for 5 min with a hot roll maintained at 1 700C and then pressed for 5 min with a hot press maintained at 1 800C. Thus, a sheet having a thickness of about 1 mm was produced. Using this sheet, physical properties were measured.

(1) Evaluation of processability on roll

Result of observation Evaluation A good sheet was obtained Good A sheet was obtained but it was scorched Slightly good A sheet was not obtainable Bad (2) Evaluation of transparency (on a pressed sheet)

Result of visual observation Evaluation It had good transparency Good It was slightly cloudy Slightly good It was translucent Bad (3) Tensile test Tensile strengths at 200C and 600C were measured in accordance with JIS K 6723.

(4) Hardness Hardness was measured at 200C by means of a JIS (A) hardness tester in accordance with JIS K 6301.

(5) Oil resistance Tensile strength retention and elongation retention were measured in accordance with JIS K 6723.

EXAMPLES 1 TO 8 AND COMPARATIVE EXAMPLES 1 TO 2 Polymerization was carried out with the formulations shown in Table 1. That is, into a 10-liter, stainless steel autoclave were charged the starting materials shown in Table 1 other than MVC. After replacing the air in the autoclave with nitrogen, MVC was fed thereto. The resulting mixture was subjected to reaction for 1 5 hr at 580C and, after removing unreacted monomers, the reaction product was dehydrated and dried to obtain a polymer powder. The physical properties measured on the polymers obtained are shown in Table 1.

In Comparative Example 1 , the production process of this invention was not employed, and 44 parts of a MVC-soluble TPU (Pandex T-5265) was blended with 56 parts of a straight PVC (Aron PVC, TS-1 1 00 manufactured by Toa Gosei Chemical Industry Co., Ltd.) The resulting blend was subjected to the same roll treatment as above. However, a sheet could not be obtained. Therefore, the massive material after rolling was subjected to hot pressing to obtain a sheet. Physical properties of this sheet were measured and the result thereof is shown in Table 1.

In Comparative Example 2, the MVC-soluble TPU used in Examples 1 to 4 was not used and instead there was used a copolymer obtained by grafting vinyl chloride on a trunk ethylene/vinyl acetate copolymer (Evaflex-45X manufactured by Mitsui Polychemical Co., Ltd.), and polymerization was conducted in the same procedure as above. Physical properties of the graft copolymer obtained were measured and the result thereof is shown in Table 1.

COMPARATIVE EXAMPLE 3 The same procedure as in Example 2 was repeated, except that Desmolac 4200 (softening point: 1 980C; insoluble in methyl ethyl ketone) (trade name of Bayer AG) was substituted for the Pandex T-5265. Because Desmolac 4200 was insoluble in vinyl chloride, the pellets of the former remained as they were, and therefore, no uniform, soft, thermoplastic resin was obtained.

COMPARATIVE EXAMPLE 4 The same procedure as in Example 2 was repeated, except that Pandex T-5000 (softening point: 1 730C; insoluble in methyl ethyl ketone) (trade name of Dainippon Ink And Chemicals, Inc.) was substituted for the Pandex T-5265. Because Pandex T-5000 was insoluble in vinyl chloride, the pellets of the former remained as they were, and therefore, no uniform, soft, thermoplastic resin was obtained.

TABLE 1

Example Comparative Example 1 2 3 4 5 6 7 8 1 2 MVC-soluble TPU (Pandex T-5265) 20 40 20 20 (Pandex T-5265L) 40 30 Polymer EVA 40 (Pandex T-5265LL) 30 40 blend Vinyl chloride 80 60 60 60 60 70 70 60 Pandex 60 T-5265 Composition Butyl acrylate 20 10 TS-1100 at the end of Vinylidene chloride 10 =44/56 feeding (Part) (Part) Pure Water 200 200 200 200 200 200 200 200 200 Partially saponified polyvinyl alcohol 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 (Gohsenol KH-17) Di-2-ethylhexyl peroxy dicarbonate 0.05 0.08 0.05 0.08 0.05 0.05 0.05 0.05 0.08 Polymerization temperature ( C) 58 58 58 58 58 58 58 58 - 58 Polymerization time (hr) 15 15 15 15 15 15 15 15 - 15 Conversion (%) 90 90 90 90 90 90 90 90 - 90 TPU content in copolymer (% by weight) 22 44 22 22 44 33 33 44 - Processability on roll Good Good Good Good Good Good Good Good Bad Good Slightly Slightly Slightly Transparency Good Good Good Good Good Good Bad good good good Tensile strength 20 C (kg/cm) 160 120 100 100 110 140 135 110 140 150 60 C (kg/cm) 80 55 40 40 45 60 55 40 70 10 TABLE 1 - Continued

Example Comparative Example 1 2 3 4 5 6 7 8 1 2 Hardness JIS (A) 90 75 65 70 72 85 83 70 90 85 Oil resistance Tensile strength retention (%) 97 98 90 92 96 98 96 95 95 40 Elongation retention (%) 96 95 115 110 97 98 95 95 96 200 As is obvious from Table 1, the polymers of this invention are sufficiently soft in the unplasticized state, and have good processability, good transparency, high tensile strengths at 600C and good oil resistance. On the other hand, the TPU/PVC blend is difficult to process on roll, and the graft copolymer manufactured using EVA is low in tensile strength at 600C and inferior in oil resistance and has no transparency.

EXAMPLE 9 Into a 10-liter stainless steel autoclave were charged 30 parts of a MVC-soluble TPU (Pandex T-5265), 200 parts of pure water, 0.8 part of a partially saponified polyvinyl alcohol (Gohsenol KH-1 7 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 0.05 part of di-2ethylhexylperoxy dicarbonate. After replacing the air in the autoclave with nitrogen, 70 parts of MVC was fed thereto and the mixture was subjected to suspension polymerization for 15 hr at 580C. After removing unreacted monomers, the residue was dehydrated and dried to obtain 90 parts of a polymer powder.

With 1 00 parts of the polymer obtained were compounded 0.5 part of calcium stearate and 0.1 part of zinc stearate. The compound obtained was pelletized at 1400 to 1 600C by means of a PVC extruder and the resulting pellets were then processed into a sheet at 1 50" to 180"C by means of a PVC extruder. This sheet was transparent and flexible and it was confirmed that it could be heat-bonded by means of a high frequency welder. Hence, infusion bags were formed from the sheet with the welder. These bags could withstand sterilization by high pressure steam.Also, when tested against all the test items specified for PVC containers in General Test Methods 42 "Test Methods for Plastic Containers for Infusion" in Pharmacopoeia of Japan (the 1 0th revision), the bags passed the standards of all the test items.

Naturally, the bags safely satisfied the standards of particularly important test items, namely, fine particles test, eluted materials test (zinc, ultraviolet absorption spectrum), acute toxicity test, intracutaneous reaction test, pyrogenous substances test and hemolysis test. In this Example, no DOP was used and accordingly there is no problem at all resulting from the use of DOP.

EXAMPLE 10 With 1 00 parts of the same polymer as obtained in Example 9 were compounded 1.5 parts of barium stearate and 0.5 parts of zinc stearate. The resulting compound was processed into a sheet having a thickness of 3.0 mm at 140 to 170"C by means of a PVC extruder. This sheet was flexible.

Also, with this sheet, oxygen index was measured in accordance with JIS K 7201 (Method for Testing Flammability of Polymeric Materials by Oxygen Index Method) to find that it was 25%. The soft thermoplastic resin obtained in this Example does not have any problems due to the migration of plasticizers because no plasticizer was used. Moreover, as compared with polyethylene (oxygen index: 17.5%), the resin is more flame-resistance and is suitable as a resin for surface protection of optical fibers.

EXAMPLE 11 With 100 parts of the same polymer as obtained in Example 9 were compounded 1.5 parts of barium stearate and 0.5 part of zinc stearate. The resulting compound was processed into a hose having an inside diameter of 25.0 mm and at thickness of 3.0 mm at 1 700C by means of a PVC extruder.

Results of elution test for this hose are shown in Table 2. Also, results of tests for physical properties of the hose are shown in Table 3.

COMPARATIVE EXAMPLE 5 One hundred parts of polyvinyl chloride FP= 1050) was compounded with 50 parts of dioctyl phthalate, 1.5 parts of barium stearate and 0.5 part of zinc stearate. The compound obtained was processed into a hose in the same procedure as in Example 11. Results of elution test for this hose are shown in Table 2, and results of tests for physical properties of the hose are shown in Table 3.

TABLE 2 (Unit: ppm)

Time (days) Temp. 1 3 5 7 30 50C ND* ND ND ND ND Example 11 23 C ND ND ND ND ND Comparative 5 C ND 0.08 0.14 0.14 0.17 Example 5 230C 0.10 0.18 0.23 0.26 Note: * ND = less than 0.05 ppm In Table 2, the elution test for hose was conducted as follows: A test sheet made from the above compound was dipped in 20% aqueous ethanol solution for a specified period of time, and the eluate was extracted with chloroform, and the extract was directly poured into a gas chromatography to determine the quantity of the eluted material.From this test, the eluted material was identified to be dioctyl phthalate.

TABLE 3

Tensile test Aging test *1 Dipping test Oil resistance *2 Low- 10% Hydraulic Tensile Elonga- tempera- 10% 30% 40% 40% Aqueous Tensile Elonga- pressure strength tion ture Distilled Sodium Sulfuric Nitric Sodium soap Soybean Engine strength tion test retention retention resistance water chloride acid acid hydroxide solution oil oil kg/cm % % % C % % % % % % % % Example 11 190 530 Pass 97 100 -45 0.08 +0.08 +0.10 -0.08 +0.01 +0.16 -0.50 +0.06 Comparative Example 5 180 350 Pass 277 3 -26 0.24 +0.17 +0.15 +0.32 -0.14 -0.88 -4.7 -4.4 Note: *1 120 C x 7 days in a gear oven *2 70 C x 24 hr In Table 3, the tensile test, the hydraulic pressure test, the aging test and the dipping test for hoses were conducted in accordance with JIS K 6771, and the low-temperature resistance and the oil resistance were tested in accordance with JIS K 6301.

EXAMPLE 12 One hundred parts of the same polymer as obtained in Example 9 was compounded with 1 part of calcium stearate and 0.5 part of zinc stearate. The resulting compound was processed into a film having a thickness of 20 u measured by the T die method at a die temperature of 1 700C by the use of a PVC extruder. Physical properties of this film are shown in Table 4 and results of its elution test are shown in Table 5.

This film was used to try to hand-wrap various containers. The film tightly adhered to these containers without causing excessive tackiness.

COMPARATIVE EXAMPLE 6 One hundred parts of polyvinyl chloride (P = 1050) was compounded with 50 parts of dioctyl phthalate, 1 part of calcium stearate and 0.5 part of zinc stearate. The resulting compound was processed into a film in the same procedure as in Example 12. Physical properties of this film are shown in Table 4.

This film was used to try to hand-wrap containers. However, excessive tackiness of the film prevented smooth hand-wrapping.

TABLE 4

Tensile Elonga- Tear Light Brittle strength tion strength transmit- temp.

Hardness (kg/cm2) (%) (kg/cm) tance (%) (DC) Example 12 89 190 420 55 92 -40 Comparative Example 6 89 1 80 320 50 92 -28 In Table 4, the hardness, tear strength and brittle temperature were measured in accordance with JIS K 6301, the tensile strength and elongation in accordance with JIS K 6723, and the light transmittance in accordance with JIS K 6714.

COMPARATIVE EXAMPLE 7 One hundred parts of polyvinyl chloride FP = 1050) was compounded with 40 parts of dioctyl adipate, 1 part of calcium stearate and 0.5 part of zinc stearate. The resulting compound was processed into a film in the same procedure as in Example 12.

Results of elution test for this film are shown in Table 5.

In Table 5, the elution test for films were conducted as follows: Each film was dipped in 20% aqueous ethanol solution or lard at the specified temperature for the specified period of time, and the eluate was extracted with chloroform, and the extract was directly poured onto a gas chromatograph to determine the quantity of the eluted material.

In Comparative Example 7, the eluted materials were identified by a gas chromatography to be dioctyl adipate.

TABLE 5 (Unit: ppm)

Time (days) Solvent Temp. 1 3 5 7 30 20% aqueous 5 C ND ND ND ND ND ethanol solution 23 C ND ND ND ND ND Example 12 -25 C ND ND ND ND ND 5 C ND ND ND ND ND Lard 23 C ND ND ND ND ND 70 C ND ND ND* ND* ND* 20% aqueous 5 C ND 0.08 0.14 0.14 0.17 ethanol solution 23 C 0.10 0.18 0.23 0.26 Comparative -25 C 0.16 0.25 0.35 0.38 0.41 Example 7 5 C 0.23 0.33 0.41 0.45 0.53 Lard 23 C 0.30 0.45 0.64 0.74 0.84 70 C 0.50 0.50 0.52* 0.66* 0.80* Note: ND = less than 0.05 ppm * Data at 70 C in Example 12 and Comparative Example 7 were obtained after 1,3,7,24 and 48 hours respectively.

EXAMPLE 13 With 100 parts of the same polymer as obtained in Example 9 were compounded 1.5 parts of barium stearate and 0.5 part of zinc stearate, and the resulting compound was formed into a sheet having a thickness of 1.0 mm by means of a PVC extruder at 1 700C according to the T-die method.

Physical properties of this sheet were as shown in Table 6.

EXAMPLE 14 With 100 parts of the same polymer as obtained in Example 9 were compounded 1.5 parts of barium stearate, 0.5 part of zinc stearate and 5 parts of antimony trioxide, and the resulting mixture was formed into a sheet in the same manner as in Example 1 3. Physical properties of this sheet were as shown in Table 6.

COMPARATIVE EXAMPLE 8 With 100 parts of polyvinyl chloride (P = 1050) were compounded 50 parts of dioctyl phthalate, 1.5 parts of barium stearate, and 0.5 part of zinc stearate, and the resulting compound was formed into a sheet in the same manner as in Example 1 3. Physical properties of this sheet were as shown in Table 6.

COMPARATIVE EXAMPLE 9 The same procedure as in Comparative Example 8 was repeated, except that 5 parts of antimony trioxide was further compounded, to form a sheet. Physical properties of this sheet were as shown in Table 6.

TABLE 6

Tensile test1) Tensile test1) after heating Oil resistance1) Migration4) Tensile Elonga- Volume1) Tensile Elonga- Low-2) Tensile Elonga- strength tion resis- strength tion temperature Oxygen3) strength tion reten- reten- tivity reten- reten- resistance index To styrene (kg/cm) (%) tion (%) tion (%) (#.cm) tion (%) tion (%) ( C) (%) resin To ABS Example 13 190 530 97 97 3 x 1014 99 99 -45 23 None None Example 14 180 500 97 100 3 x 1014 102 103 -44 30 None None Comp.Ex.8 180 350 110 78 6 x 1013 106 90 -26 24 Remarkable Remarkable Comp.Ex.9 180 340 104 75 6 x 1013 110 88 -26 30 Remarkable Remarkable Note: 1) Measured according to JIS K 6723.

2) Measured according to JIS K 6301.

3) Measured according to JIS K 7201.

4) A pressed sheet having a thickness of 0.5 mm was placed between the resin plates to be tested, a load of 1 kg/cm was applied to the resulting assembly, and the assembly was allowed to stand in a gear oven at 70 C for 3 days under said load, after which the degree of contamination of the resin plates was observed visually to determine the migration.

EXAMPLE 1 5 The same procedure as in Example 9 was repeated, except that 40 parts of Pandex T-5265 was substituted for the 30 parts of Pandex T-5265 and 60 parts of MVC was substituted for the 70 parts of MVC, to obtain 90 parts of a polymer powder.

With 100 parts of the polymer thus obtained were compounded 1.5 parts of barium stearate and 0.5 part of zinc stearate, and the resulting compound was kneaded on a 16-inch mixing roll at 1 700C, and then subjected to a 8-inch calender roll at 1 7O0C together with a Tetron plain-woven substrate having a thickness of 0.2 mm, to form a laminate having a thickness of 0.6 mm. The laminate (leather) thus obtained had a good texture and was free from pinholes. Physical properties of this laminate were measured according to JIS K 6772 to obtain the results shown in Table 7.

TABLE 7

Tensile Elonga- Tear Peeling Low load tion load load temperature (kgf) (%) (kgf} (kgf) resistance Longitudinal 30 10 1.2 2.0 Passed Transverse 25 15 1.2 2.0

Claims (29)

1. A process for producing a soft thermoplastic resin, that comprises polymerizing monomeric vinyl chloride or a monomer mixture consisting of monomeric vinyl chloride and a monomer copolymerizable with monomer vinyl chloride and that gives a homopolymer having a glass transition temperature of less than 300C, in the presence of an aqueous medium, a suspending agent and an oilsoluble polymerization initiator, and in the presence of 10 to 200 parts by weight of a thermoplastic polyurethane elastomer soluble in monomeric vinyl chloride and having a softening point of 200C to 100 C, per 100 parts by weight of the said monomer or monomer mixture.

2. A process according to Claim 1, in which the thermoplastic polyurethane elastomer has a softening point of 300C to 600C.

3. A process according to Claim 1 or 2 in which the th2rmoplastic polyurethane elastomer is composed mainly of a polyesterdiol and an aliphatic diisocyanate.

4. A process according to Claim 3, in which the polyester diol is adipic ester diol.

5. A process according to Claim 3 or 4, in which the aliphatic diisocyanate is tetramethylene diisocyanate, pentamethylene diisocyanate, or hexamethylene diisocyanate.

6. A process according to any one of Claims 1 to 5, in which the thermoplastic polyurethane elastomer has a 20% methyl ethyl ketone viscosity of 30 to 1 ,000 cps.

7. A process according to Claim 6, in which the said viscosity is 50 to 400 cps.

8. A process according to Claim 7, in which the said viscosity is 100 to 300 cps,

9. A process according to any one of Claims 1 to 8, in which the thermoplastic polyurethane elastomer is present in a proportion of 2G to 1 50 parts by weight per 100 parts by weight of the monomer or monomer mixture.

10. A process according to any one of Claims 1 to 9, in which the monomeric vinyl chloride is polymerized alone.

11. A process according to any one of Claims 1 to 9, in which a monomer mixture consisting of vinyl chloride and a monomer that is copolymerizable with vinyl chloride and that gives a homopolymer having a glass transition temperature of less than 300C is polymerized.

1 2. A process according to Claim 11, in which the copolymerizable monomer is at least one olefin, vinylidene haiide, vinyl ester of saturated carboxylic acid, alkyl vinyl ether, alkyl acrylate and/or alkyl methacrylate.

13.A process according to Claim 11 or 12, in which the quantity of the copolymerizable monomer is 50% by weight or less based on the weight of the monomer mixture.

14. A process according to Claim 13, in which the said quantity is 30% by weight or less.

1 5. A process according to any one of Claims 1 to 14, in which the suspending agent is at least one member of the following: partially saponified polyvinyl alcohols, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, polyacrylic acids, vinyl ether/maleic anhydride copolymers, gelatin and calcium phosphate.

1 6. A process according to any one of Claims 1 to 1 5, in which the quantity of the suspending agent is 0.01 to 2% by weight based on the weight of the aqueous medium.

1 7. A process according to any one of Claims 1 to 1 6, in which the oil-soluble polymerization initiator is azobisisobutyl-valeronitrile, lauryl peroxide, di-2-ethylhexylperoxy dicarbonate or tbuty!peroxy pivalate.

1 8. A process according to any one of Claims 1 to 1 7, in which the quantity of the oil-soluble polymerization initiator is 0.01 to 2% by weight based on the weight of the monomer or monomer mixture.

1 9. A process according to any one of Claims 1 to 1 8, in which the weight ratio of the aqueous medium to the monomer or monomer mixture plus the thermoplastic polyurethane elastomer is in the range 1:1 to 3:1.

20. A process according to any one of Claims 1 to 17, in which the polymerization is carried out at a temperature in the range 300C to 700 C.

21. A process according to Claim 20, in which the temperature range is 4O0C to 6O0C.

22. A process according to Claim 1 , carried out substantially as hereinbefore described in any one of the foregoing Examples.

23. A soft thermoplastic resin produced by a process according to any one of Claims 1 to 22.

24. A medical appliance formed from a soft thermoplastic resin according to Claim 23.

25. An optical fiber cable, the surface of which is coated with a soft thermoplastic resin according to Claim 23.

26. An electrical wire coated with a soft thermoplastic resin according to Claim 23.

27. A laminate in which a soft thermoplastic resin according to Claim 23 is laminated to a sheetshaped substrate.

28. A wrapping film made from a soft thermoplastic resin according to Claim 23.

29. A hose made from a soft thermoplastic resin according to Claim 23.