JPH07188493A - Cold-resistant material - Google Patents

Abstract

PURPOSE:To obtain a material reduced in permanent compression set and having excellent strengths, good cold resistance and good heat resistance. CONSTITUTION:This material is made by molding a polyvinyl chloride resin composition comprising 100 pts.wt. polyvinyl chloride resin 20-200 pts.wt. core/ shell latex rubber composed of a core material comprising a crosslinked polybutyl acrylate and a shell material comprising a resin excellent in compatibility with the polyvinyl chloride and having a shell thickness of 5-50nm and having a mean article diameter of 0.05-5mum and 20-200 pts.wt. 100 pts.wt. total weight of the polyvinyl chloride resin and the core/shell latex rubber, at least one plasticizer having a solidification temperature of -30 deg.C or below and selected from the group consisting of phthalate, adipate-, sebacate-, azelate, trimellitate- and phosphateplasticizers.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention comprises a PVC composition containing a polyvinyl chloride resin (hereinafter referred to as PVC), a core-shell type latex rubber and a plasticizer, and is excellent in compression set and material strength, and is resistant to cold. The present invention relates to a cold-resistant rubber molded material having good heat resistance and heat resistance.

[0002]

2. Description of the Related Art A rubber-like molded article having excellent flexibility and elasticity can be obtained by blending PVC with an appropriate amount of a plasticizer represented by DOP (di-2-ethylhexyl phthalate). Widely used for sealing materials, pads, boots, etc. However, this composition cannot be said to have sufficient rubber elastic properties such as compression set, and when it is used for a rubber molding material for automobiles, the elastic modulus change is small at the operating temperature and the heat resistance and cold resistance are improved. Molded rubber products are required.

It is generally known that when a crosslinked or partially crosslinked NBR (acrylonitrile-butadiene rubber) having a good compatibility with PVC is blended with PVC, the compression set is improved. At present, the strain is not sufficient, and further improvement in cold resistance is desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rubber molded article material which is excellent in compression set and material strength and has good cold resistance and heat resistance.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present inventors have made extensive studies as to a resin composition obtained by blending a core-shell type latex rubber in a mixed system of PVC and a plasticizer. The present invention has been completed. That is, the present invention uses a specific core based on 100 parts by weight of PVC.
20 to 200 parts by weight of a shell type latex rubber, and 20 to 200 parts by weight of a specific plasticizer based on 100 parts by weight of PVC and the core-shell type latex rubber are molded into a PVC composition. It is a cold-resistant material. The details of the present invention will be described below.

The PVC used in the present invention is a vinyl chloride homopolymer resin, a chlorinated vinyl chloride resin, one or more of all monomers copolymerizable with a vinyl chloride monomer, and a random copolymer or block. It is a vinyl chloride copolymer resin obtained by copolymerization, and as the copolymerizable monomer, ethylene, vinyl acetate, vinylidene chloride, methyl methacrylate, methacrylic acid esters such as ethyl methacrylate, methyl acrylate, acrylic acid Examples thereof include acrylic acid esters such as ethyl, alkylmaleimides such as methylmaleimide and ethylmaleimide, maleimide monomers such as phenylmaleimide, styrene-based monomers such as styrene and α-methylstyrene, and acrylonitrile. It is also possible to use a single product of the above resins or a mixture of two or more kinds.

The structure of the core-shell type latex rubber used in the present invention is mainly composed of butyl acrylate as a main component, but having two or more double bonds having the same reactivity, for example, aromatic divinyl such as divinylbenzene. The core material crosslinked with a monomer or a compound such as butylene glycol diacrylate, and the surface portion of the core material is P
A core-shell latex comprising a shell material composed of a resin having excellent compatibility with VC. If the core material is crosslinked regardless of the degree of crosslinking, the object of the present invention is achieved. The embrittlement temperature, which is a measure of cold resistance, is the minimum glass transition temperature (T
g) PVC used in the present invention, determined by the component
In the composition, the glass transition temperature of the core material portion corresponds to that.

The core-shell type latex rubber used in the present invention can be prepared to have a uniform average particle diameter of the core material and an average thickness of the shell material by carrying out multistage emulsification and seed polymerization. In the present invention, the core material portion having an average particle diameter of 0.05 to 5 μm is used, and further preferably 0.15 to 1 μm. If the average particle size is smaller than 0.05 μm, it is difficult to develop sufficient rubber elasticity, that is, compression set, and if it is larger than 5 μm, the material strength may be impaired. Further, those having a large average particle diameter are effective in improving the compression set when the same amount is added.

The amount of the core-shell type latex rubber added to the PVC composition used in the present invention is PVC1.
The amount is 20 to 200 parts by weight, more preferably 40 to 150 parts by weight, relative to 00 parts by weight. If this amount is less than 20 parts by weight, not only the rubber elasticity of the obtained material, that is, the compression set is not improved, but also sufficient heat resistance and cold resistance cannot be obtained. Although the strain is improved, other physical property balances such as material strength are impaired.

The chemical composition of the shell material resin of the core-shell type latex rubber used in the present invention is such that it contains at least one monomer having excellent compatibility with PVC. The term "compatibility" as used herein means that two types of polymers are prepared by an appropriate mixing method (melt blending, solution blending),
For example, it refers to a mixed state in which the glass transition temperature (Tg) in differential scanning calorimetry (DSC) or dynamic viscoelasticity measurement is single. Such resins for shell materials having excellent compatibility with PVC include not only PVC but also polyesters such as polymethacrylic acid esters such as polymethylmethacrylate and polyethylmethacrylate, polycaprolactone, polyester-based polyurethane, And ethylene-vinyl acetate copolymer, styrene-acrylonitrile copolymer, etc.
Examples thereof include copolymers composed of monomers that are components or more.
This compatibility is reflected in the material strength through the interfacial adhesion between the two phases (layers), and the interfacial adhesion between PVC and the core-shell type latex rubber can be determined by the peel strength of the laminate. . That is, a 2 mm thick sheet of PVC (di-2-ethylhexyl phthalate (DO
P) is included in 100 parts by weight with respect to 100 parts by weight of PVC)
A laminate of a 2 mm thick sheet of core-shell type latex rubber and a core-shell type latex rubber was subjected to a peeling test at a pulling speed of 50 mm / min to perform PV test.
When C and the shell material are compatible, the peel strength is preferably 15
It is 0 g / cm or more, more preferably 700 g / cm or more. Incidentally, when the shell material is a styrene-acrylonitrile copolymer, it is 900 g / cm, and when it is polymethyl methacrylate, it is 800 g / cm.

The thickness of the shell material of the core-shell type latex rubber used in the present invention is 5 to 50 nm, more preferably 10 to 30 nm. That is, when the shell thickness is less than 5 nm, the resulting composition has excellent flexibility as a rubber, but the resin constituting the PVC and the shell material, or the entanglement between the shell materials is not sufficient, and the material strength is impaired. On the other hand, by increasing the thickness of the shell material, the material strength and compression set are improved, but if it is thicker than necessary, the material strength will be excellent, but the hardness of the composition will be extremely high and the molded product will be resin-like and thermoplastic. The flexibility as an elastomer is impaired. It should be noted that the shell thickness and the entanglement referred to here have a close relationship, and when the shell thickness is the same, the smaller the inter-entanglement molecular weight is, the more easily they are entangled. In the present invention, the inter-entanglement molecular weight is preferably 20000 or less. , And more preferably 15,000 or less.

The plasticizer used in the present invention has a freezing point of −30 ° C. or lower in order to exhibit cold resistance, and more preferably a plasticizer having a good compatibility with the polybutyl acrylate used as the core material. To be Such plasticizer is selected from adipic acid plasticizer, sebacic acid plasticizer, phthalic acid plasticizer, azelaic acid plasticizer, trimellitic acid plasticizer and phosphoric acid plasticizer,
One or more of these plasticizers are used. The molecular weight of the plasticizer is not particularly limited as long as it does not affect the freezing point.

The amount of the plasticizer used is 20 per 100 parts by weight of the total weight of PVC and core-shell type latex rubber.
To 200 parts by weight, preferably 30 to 100 parts by weight, and more preferably 40 to 70 parts by weight. That is, if the amount is less than 20 parts by weight, the obtained material lacks flexibility,
On the other hand, when the amount exceeds 200 parts by weight, the material has flexibility, low viscosity,
Although excellent in compression set, the material strength is remarkably impaired, and the problem of bleeding of the plasticizer such as stickiness on the surface occurs.

The PVC composition used in the present invention is a thermoplastic resin excellent in compatibility with PVC to the extent that the performance thereof is not extremely deteriorated, and calcium carbonate, talc, clay, carbon black, metal usually added to PVC. Inorganic fillers represented by oxides, flame retardants represented by antimony trioxide and zinc borate, heat stabilizers such as barium stearate and zinc stearate, antioxidants, and various additives such as UV absorbers. Can be added as required.

The cold-resistant material of the present invention is obtained by molding the above-mentioned PVC composition. The kneading and molding method for this molding is not particularly limited, and a general kneading and molding method can be used. That is, a PVC composition prepared by blending PVC, a plasticizer, and a core-shell type latex rubber is heated and melt-mixed under a shearing force by a roll kneader, a Banbury type kneader, a uniaxial or biaxial extruder, or the like. The PVC composition can be easily kneaded by heating, and the kneaded product of the PVC composition can be easily heat-melt-molded by using an ordinary molding method such as a press molding machine, an extrusion molding machine, or an injection molding machine.

The above-mentioned material of the present invention becomes a material for a rubber molded article which is excellent in rubber elastic properties such as compression set and cold resistance and heat resistance, and is molded by using the above-mentioned appropriate molding method. It can be widely used as a cold-resistant material member such as a hose / tube, packing / sealing material, pad, boot, grommet, and gasket.

[0017]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 100 parts by weight of ethylene-vinyl chloride copolymer (Leuron E-2800, manufactured by Tosoh Corporation) as PVC, 2 parts by weight of barium stearate as stabilizer, 1 part by weight of zinc stearate, plasticizer As di-2-ethylhexyl phthalate (DOP (freezing point −55 ° C., “Plasticizer, Theory and Application” by Murai Shokobo, all numerical values of freezing point of plasticizer are quoted from the same literature)) and dioctyl adipate (DOA , Freezing point -70 ° C or less) (5 by weight ratio)
/ 5) to 100 parts by weight with respect to PVC, core-shell latex (Tafideroid 141 manufactured by Takeda Pharmaceutical Co., Ltd.)
3, average particle diameter 0.6 μm, shell composition acrylonitrile (AN) -styrene copolymer (AN content = 25 wt
%, Molecular weight between entanglement points 11500), shell thickness 10
˜15 nm) was blended in an amount of 70 parts by weight and melt-kneaded using an 8-inch roll at 150 ° C. for 15 minutes. The obtained mixed sample was press-molded and subjected to each material test. The test results are shown in Table 1.

Example 2 Other core-shell latex (Stafloyd 1414 manufactured by Takeda Pharmaceutical Co., Ltd., average particle diameter 0.6 μm, shell composition polymethyl methacrylate (molecular weight between entanglement points: 92)
00) and a shell thickness of 25 to 30 nm), and a sample was obtained and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Other core-shell latex (Stuffyroid 1415 manufactured by Takeda Pharmaceutical Co., Ltd., average particle size 0.6 μm, shell composition methyl methacrylate / 2-ethylhexyl acrylate copolymer, shell thickness 25-30 nm) Samples were obtained and evaluated in the same manner as in Example 1 except that (1) was used. The results are shown in Table 1.

Example 4 As plasticizers, DOP and DOS (dioctyl sebacate,
A sample was obtained and evaluated in the same manner as in Example 1 except that a mixture (freezing point −55 ° C.) (mixing weight ratio 5/5) was used. The results are shown in Table 1.

Comparative Example 1 100 parts by weight of ethylene-vinyl chloride copolymer (Leuron E-2800, manufactured by Tosoh Corporation) as PVC, 2 parts by weight of barium stearate, 1 part by weight of zinc stearate and a plasticizer as stabilizers. As dioctyl phthalate (D
OP) and dioctyl adipate (DOA) mixture (5/5 by weight) to 100 parts by weight of PVC, partially crosslinked NBR (PNC-38 manufactured by Nippon Synthetic Rubber Co., Ltd., acrylonitrile content 40%, particle size 0). .05-0.1 μm)
The same molding and material test as in Example 1 was carried out except that the composition obtained by blending 70 parts by weight was used. The results are shown in Table 1.
Shown in.

Comparative Example 2 A mixture of DOP and DOS as a plasticizer (mixing weight ratio 5
Molding and material tests were performed in the same manner as in Comparative Example 1 except that / 5) was used. The results are shown in Table 1.

The method of material test will be described below.

(Evaluation of compression set) JIS K6301
A compression set test was conducted in accordance with (70 ° C, 22 hours).

(Evaluation of material strength) Measurement was carried out in accordance with JIS K6723.

(Evaluation of cold resistance) Nondestructive temperature and embrittlement temperature were evaluated according to JIS K6301.

(Evaluation of heat resistance) The heat distortion rate was evaluated according to JIS K6723.

[0029]

[Table 1]

[0030]

As described above, according to the material of the present invention, it is possible to obtain a rubber molded article which is excellent in compression set and material strength, and is also excellent in cold resistance and heat resistance.

Claims (1)

[Claims] 1. A core-shell latex rubber as described in (mark 1) is 20 to 200 parts by weight, and a plasticizer as described in (mark 2) is polyvinyl chloride based on 100 parts by weight of a polyvinyl chloride resin. A cold-resistant material obtained by molding a polyvinyl chloride resin composition in an amount of 20 to 200 parts by weight based on 100 parts by weight of the total weight of the resin and the core-shell type latex rubber. (Item 1) The average particle diameter is 0.05 to 5 μm, the core material is a polybutyl acrylate crosslinked body, the shell material is made of a resin having excellent compatibility with a polyvinyl chloride resin, and the thickness is 5 to 50 nm. A core-shell type latex rubber. (Item 2) At least one selected from phthalic acid plasticizers, adipic acid plasticizers, sebacic acid plasticizers, azelaic acid plasticizers, trimellitic acid plasticizers and phosphoric acid plasticizers. And a plasticizer having a freezing point of −30 ° C. or lower.