JPH056502B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention heat-treats a molded product obtained by molding a vinyl chloride resin composition by injection molding or extrusion, thereby reducing permanent deformation such as compression set and permanent elongation. The present invention relates to a method of manufacturing a molded product for a vehicle that is smaller in size. More specifically, the method for manufacturing soft vinyl chloride molded products with low permanent deformation that are used for vehicles that require high elasticity, such as gaskets, tubes, gaskets, glass launch channels, weather strips, etc. Regarding. [Prior Art] Generally, when a plasticizer is added to a vinyl chloride resin, a flexible molded product having appropriate elasticity can be obtained and is used in various fields. [Problems to be solved by the invention] However, molded products made from general soft vinyl chloride resin compositions have large compression set and poor restoring force after stress is applied. Small compression set is required for injection molded products such as gaskets and grommets, automotive products such as weather strips, door glass runs, and gaskets obtained by extrusion molding. Its use is restricted to certain applications. As a means to solve this technical problem, a method using vinyl chloride resin with a high average degree of polymerization was proposed,
As disclosed in JP-A-54-80354, JP-A-56-79141, etc., a method using a partially cross-linked vinyl chloride resin having a gel content that is insoluble in tetrahydrofuran, or a method using JP-A-56-79141. −
As disclosed in JP-A No. 115342, JP-A-59-51933, etc., a composition in which a partially crosslinked acrylonitrile-butadiene copolymer having a gel content that is insoluble in methyl ethyl ketone is blended with a vinyl chloride resin. Depending on the method of using things, etc.
It is generally known that compression set can be improved to some extent, but
The compression set is large compared to EPDM, NBR, chloroprene rubber, etc., and its applications are actually limited. The present invention is applicable to molded products such as packing and grommets obtained by injection molding general soft vinyl chloride resin compositions, weather strips obtained by extrusion molding, automobile parts such as door glass runs, gaskets, etc. Problems such as the large compression set of molded products, which limits their applications, and the use of highly polymerized vinyl chloride resins or partially crosslinked vinyl chloride resins with a gel content that is insoluble in tetrahydrofuran, or the use of these vinyl chloride resins. By using a soft vinyl chloride resin composition that is a blend of a partially crosslinked acrylonitrile-butadiene copolymer with a gel content that is insoluble in methyl ethyl ketone, the compression set of the resulting molded product is equal to that of a normal vinyl chloride resin composition. Although it is improved compared to molded products obtained from materials, its physical properties such as compression set are inferior compared to EPDM, NBR, and chloroprene rubber vulcanized with sulfur or organic peroxides, and its applications are limited. It was done to solve a problem. [Means for Solving the Problems] The present invention provides 100 parts of vinyl chloride resin (parts by weight,
For vehicles, the molded product obtained by molding a vinyl chloride resin composition comprising (the same applies hereinafter) and 20 to 200 parts of a plasticizer is heat-treated at a temperature of 50 to 120°C for 20 minutes to 24 hours. The present invention relates to a method for manufacturing an injection molded product or an extrusion molded product. [Example] The vinyl chloride resin used in the present invention is a vinyl chloride resin obtained by homopolymerizing a vinyl chloride monomer, or a vinyl chloride resin whose main component is vinyl chloride, i.e.
A vinyl chloride copolymer resin containing 85% (by weight, the same shall apply hereinafter) or more, and specific examples of the latter include vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-ethylene copolymer resin, and vinyl chloride-propylene copolymer resin. Polymer resin, copolymer resin of vinyl chloride and acrylic acid or its ester, copolymer resin of vinyl chloride and methacrylic acid or its ester,
Examples include, but are not limited to, copolymer resins of vinyl chloride and alkyl vinyl ether. These vinyl chloride copolymer resins may be blended in a subordinate amount (up to 30%) to the vinyl chloride resin. As the vinyl chloride resin used in the present invention, JP-A-56-81325 other than the above vinyl chloride resin
Publication No. 1981-81328, Japanese Patent Application Laid-Open No. 1987-81328
A partially crosslinked vinyl chloride resin having a gel content that is insoluble in tetrahydrofuran as disclosed in Japanese Patent No. 195711 may also be used. The plasticizer used in the present invention is added to soften the resin composition used in the present invention,
The amount added is 20 to 200 per vinyl chloride resin.
parts, preferably 30 to 160 parts. The amount added is
If the amount is less than 20 parts, the molded product will not be sufficiently softened, and the effect of reducing permanent deformation due to heat treatment, that is, the development of rubber-like properties, will not occur. On the other hand, if the amount exceeds 200 parts, it becomes difficult to dry up, and the molded product becomes sticky after injection molding or extrusion molding, which is undesirable since there are problems in terms of processing and practical use. Examples of the plasticizers include phthalic acid plasticizers such as dioctyl phthalate, dinonyl phthalate, and diisodecyl phthalate, fatty acid plasticizers such as dioctyl adipate and dioctyl azelaate, trimellitic acid plasticizers such as trioctyl trimellitate, and polyesters. These include plasticizers commonly used in soft vinyl chloride resin compositions, such as epoxidized products such as epoxidized soybean oil, phosphoric acid plasticizers such as tricresyl phosphate, and chlorinated paraffin. It may be used or two or more types may be used in combination, and they can be used without particular limitation. In the present invention, a vinyl chloride resin composition is prepared from a vinyl chloride resin and a plasticizer.
Rubber substances may also be added. Examples of such rubber materials include acrylonitrile-butadiene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide terpolymer, chlorinated polyethylene, thermoplastic polyurethane, thermoplastic polyester, Examples include chloroprene rubber and acrylic rubber.
Among these rubber substances, JP-A-59-51933
As disclosed in the publication, the solubility in methyl ethyl ketone is 90% or less, and during its production, a polyfunctional monomer such as divinylbenzene is added to the polymerization system to create a crosslinked structure in the molecule. Acrylonitrile-butadiene copolymer is particularly preferred since it has the effect of reducing compression set. The rubber substances may be used alone or in combination of two or more, and the amount used is preferably 150 parts or less per 100 parts of the vinyl chloride resin. If the amount exceeds 150 parts, processability tends to deteriorate and the unique properties of vinyl chloride resins, such as good heat aging resistance, ozone resistance, and mechanical properties, tend to be lost. This is not desirable because it does things like this. In addition, heat stabilizers, fillers, lubricants,
Ultraviolet absorbers, pigments, blowing agents such as azodicarbonamide, processing aids such as copolymers of methyl methacrylate and butyl acrylate, and the like may be blended and used. The types and amounts of subcomponents used as necessary may be appropriately selected and used within a range that satisfies the above ratios depending on the purpose. The resin composition used in the present invention is mixed, kneaded, and granulated in the same steps as conventional soft vinyl chloride resin compositions, and can be molded by injection molding, extrusion molding, or the like. That is, they can be mixed together with a stabilizer, if necessary, using a mixer such as a super mixer or a ribbon blender, and the mixture is kneaded and granulated using a Banbury mixer, mixing roll, extruder, or the like. The granulated pellets are molded by a method such as press molding, injection molding, or extrusion molding, and the resulting molded product is heated at a temperature of 50 to 120°C, preferably 50 to 110°C for 20 minutes or more, preferably 1 hour or more. Heat treatment significantly reduces the permanent set of the molded product, especially the compression set. For heat treatment of the molded article, it is sufficient to simply leave it in a heating furnace such as a hot air dryer. The heat treatment temperature is 50℃
If it is less than 120°C, the permanent set, especially the compression set, will not be improved, and if it exceeds 120°C, the molded product will deform and become unable to hold its shape, which is not preferable. Moreover, if the heat treatment time is less than 20 minutes, it becomes impossible to reduce the compression set. The method of the present invention will be explained below based on Examples, but the present invention is not limited thereto. In addition, each physical property in an Example was measured by the following method. (Gel content insoluble in tetrahydrofuran) Extracted with hot tetrahydrofuran for 22 hours using a Soxhlet extractor, and measured the extracted residue separated with a 350 mesh filter. (Solubility of NBR in methyl ethyl ketone (hereinafter referred to as MEK)) 1 g of block-like NBR was added to 100 ml of MEK at 25°C.
Soak for an hour and measure the percentage of solution and particles that pass through a 100-mesh filter. (Compression set of molded product) Test pieces for measuring compression set were made using the following three processing methods, and the compression set of the molded product was measured. (1) How to make press-formed products and measurement methods Dry blends of each formulation shown in Table 1 were rolled at a temperature of 160℃ (175℃ for formulations 2 and 3).
Knead for 7 minutes to make a masticated sheet with a thickness of about 3 mm, overlap the resulting sheets and make a 170 mm
℃ (180℃ for formulations 2 and 3) for 4 minutes, then 170℃ (180℃ for formulations 2 and 3)
For 3 minutes, apply a load of 150Kg/cm ² to a thickness of 12.7
A press plate of 29.0 mm in diameter was made, hollowed out into a right cylinder shape with a diameter of 29.0 mm, and heat treated under the conditions shown in Table 2.
Compliant with 6301, compression rate 25%, compression condition 70℃
Measurement of compression set after 22 hours. (2) How to make and measure injection molded products A masticated sheet with a thickness of about 3 mm was prepared using each compounding system shown in Table 1 in the same manner and under the same conditions as above, and the resulting sheet was divided into approximately 3 mm squares. Cut into pellets, use the pellets to apply mold clamping pressure of 150 tons,
With an injection molding machine with an injection capacity of 173 cm ³ /shot,
Using a mold with a thickness of 12 mm, length of 50 mm, and width of 100 mm, the cylinder temperature was 165°C (180°C for composition 3).
Nozzle temperature 160℃ (175℃ for formulation 3),
Injection molding was performed at an injection pressure of 50 Kg/cm ² . A right cylindrical object with a diameter of 29.0 mm was cut out from the obtained molded plate, and heat treated under the conditions shown in Table 3 to obtain JIS K.
Compliant with 6301, compression ratio 25%, compression condition 22 at 70℃
Measure the compression set after time. (3) How to make and measure extrusion molded products The same method as above was used for the formulation 3 shown in Table 1.
A masticated sheet with a thickness of approximately 3 mm was prepared under the following conditions.
The obtained sheet was cut into approximately 3 mm squares to make pellets, and the pellets were used with a full flight screw with L/D = 22 and compression ratio of 3.0.
Extrude the profile extrusion molded product (sealing member for automobiles) (1) shown in Figure 1 using a 50 mm single screw extruder, and
Heat treated under the conditions shown in the table, and the molded product was JIS K certified using the apparatus 2 having the spacer 3 shown in Fig. 2.
It was measured using the same method as the compression set measurement method for 6301. The compression rate was 53%, the compression conditions were 70℃ for 22 hours, and the extrusion molding conditions were cylinder temperatures from the hopper side: C ₁ 150℃, C ₂ 160℃, C ₃ 170℃,
The C ₄ temperature was set at 175°C, the die temperature was set at 175°C, and the screw rotation speed was 30 rpm. (Appearance after heat treatment) The press molded, injection molded, and extrusion molded products described above were placed in a hot air dryer and heat treated under the heat treatment conditions shown in Tables 2, 3, and 4. The change in gloss was observed and evaluated based on the following criteria. ○: No change △: Small change ×: Large change Examples 1 to 6 and Comparative Examples 1 to 2 The formulations shown in Table 1 were roll kneaded, a press molded product was produced from the resulting masticated sheet, and the The molded product was placed in a hot air dryer under the heat treatment conditions shown in Table 2, and the appearance after heat treatment was observed.
Compression set was measured in accordance with K 6301. The results are shown in Table 2. Note that S 1003 and S3000 in Table 1 are Kanevinyl S1003 (=
1300) and Kanevinyl S3000 (3200), partially crosslinked vinyl chloride resin has THF insoluble content of 19%, acrinitrile-butadiene copolymer has acrinitrile content of 33%, MEK solubility 21%, Moony Acrynitrile-butadiene copolymer with a viscosity of 50, DOP is dioctyl phthalate.

【table】

[Table] From the results in Table 2, the heat treatment temperature for formulation 1 is 23
The compression set in 24 hours at ℃ is 60%, but as the heat treatment temperature increases and the heat treatment time increases, the compression set improves to 57, 54, and 43%, and the heat treatment temperature increases.
Compression set at 130°C for 1 hour was not improved, and the appearance of the molded product changed. It can also be seen that formulations 2 and 3 show the same tendency. In particular, it can be seen that when Blend 3 is heat treated at a heat treatment temperature of 50°C and 70°C for 24 hours, the compression set is significantly improved to 29% and 25%, respectively. Examples 7 to 10 and Comparative Examples 3 to 4 Pellets were prepared using the formulations 1 and 3 in Table 1, and the molded products injection molded under the above injection conditions were hot-air dried under the heat treatment conditions in Table 3. After processing in a machine, the appearance was observed and the compression set was measured in accordance with JIS K 6301. The results are shown in Table 3.

[Table] From the results in Table 3, the compression set of formulation 1 after 24 hours at a heat treatment temperature of 23°C is 59%;
It can be seen that when heat treated at 50°C for 24 hours, the improvement was 49%, and at 70°C, the improvement was 52% after 1 hour of heat treatment and 46% after 24 hours. However, when heated at 130°C for 1 hour, the compression set was as large as 62%, and the appearance of the molded product also changed. On the other hand, the injection molded product made using the formulation 3 was heat treated at 23℃ for 24 hours.
Compression set at 130℃ for 1 hour is 47% and 48%, respectively.
However, it can be seen that when heat treated at 70°C for 1 hour and 24 hours, the compression set was significantly improved to 35% and 27%, respectively. Examples 11 to 14 and Comparative Examples 5 to 6 Pellets were prepared using the formulation 3 in Table 1, and extruded under the extrusion conditions into the shape of the automotive sealing member shown in Figure 1. were heat treated in a hot air dryer under the heat treatment conditions shown in Table 4, and the compression set was measured using the apparatus shown in FIG. The results are shown in Table 4.

【table】

[Table] From the results in Table 4, the compression set under heat treatment conditions of 23℃ for 24 hours and 130℃ for 1 hour is 58%,
59%, but the heat treatment conditions are 50℃ for 24 hours and 70℃
When heat treated for 24 hours, the compression set was 43% and 40%, respectively.
It can be seen that there is a significant improvement of %. [Effect of the invention] When the resin composition used in the present invention is molded by a method such as press molding, injection molding, or extrusion molding, and the molded product is heat-treated by the method of the present invention, the compression set of the molded product can be significantly reduced. can be improved,
EPDM vulcanized with sulfur or organic peroxide,
Molded products with permanent deformation equivalent to NBR, chloroprene rubber, etc. can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional explanatory diagram of an extrusion molded product of a sealing member for automobile parts for evaluating the compression set of a vinyl chloride type resin molded product, and Figure 2 is a cross-sectional diagram of an extrusion molded product of a sealing member for automobile parts for evaluating the compression set of a vinyl chloride type resin molded product. FIG. 2 is an explanatory diagram showing a state in which . (Main symbols in the drawing), 1: Profile extrusion molded product.

Claims (1)

[Claims] 1 100 parts by weight of vinyl chloride resin and 20 parts by weight of plasticizer
An injection molded product for a vehicle, characterized in that a molded product obtained by molding a vinyl chloride resin composition comprising ~200 parts by weight is heat-treated at a temperature of 50 to 120°C for 20 minutes to 24 hours. Method for manufacturing extruded products.