JPS61111337A - Preparation of vinyl chloride resin composition for sinter foaming - Google Patents

Abstract

PURPOSE:To prepare the titled compsn. producing uniform, fine expanded cells, by incorporating a powdered vinyl chloride resin with a dispersion of a thermally decomposable blowing agent in a plasticizer. CONSTITUTION:A thermally decomposable blowing agent with an average particle size of 30mu or below (e.g., azodicarbonamide) (A) and a plasticizer (e.g., dioctyl phthalate) (B) are blended by a ribbon blender, butterfly mixer, etc. and then mixed in an ink mill to disperse the component A into the component B forcibly, thus forming a dispersion. 100pts.wt. powdered vinyl chloride resin having a particle size of 40-300mesh, a mean degree of polymn. of 500-150, and the content of vinyl chloride of 50wt% or more is incorporated with the resulting dispersion so that the component A of 1-10pts.wt. and the component B of 30-130pts.wt. are attained to yield a vinyl chloride resin compsn. for sinter foaming. Then, the compsn. is applied onto a plain belt, and sintered and foamed by heating at 150-300 deg.C for several sec - 30min.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing a powdered vinyl chloride resin composition for sintering and foaming, and more specifically, to a method for producing a pyrolytic foaming agent as a plasticizer dispersion. The present invention relates to a method for producing a PVC composition for sintering and foaming, which is characterized in that it is added to a vinyl chloride resin (hereinafter sometimes referred to as PVC) powder, and which forms homogeneous and fine foam cells.

(Prior art) In addition to extrusion molding, injection molding, etc., conventional methods for producing foamed PVCG shaped products include so-called powder molding methods such as fluidized dipping, electrostatic coating, powder coating, rotary molding, and slush molding. There is. This molding method is a molding method in which a powder composition is attached to the surface of a molding die or a painted surface, and sintered by heating and melting to produce a molded product or a coating film, and the molding equipment is relatively simple. The shape of the resulting molded product can be made into any shape depending on the purpose, such as paint films, sheets, three-dimensional products (day objects), etc., so it can be used for automobile interior parts, leather, toys, sports goods, etc. It is widely used in the production of However, the resulting powder molded product is generally in the form of a thin film, so in order to obtain a thin foam molded product with a skin layer, the powder molding method is usually used to make the thin-walled molded product t-i, and then the molded product is The process is complicated, as it involves a two-step molding process in which the product is lined with polyurethane foam resin, etc. Moreover, since the molded skin is generally a thin sheet with a thickness of around 1sII,
When attaching the skin to the foam mold, there is a drawback that wrinkles and folding marks remain on the curved parts.

Therefore, in order to simplify the process, a method of manufacturing a foam layer in a powder molding process was proposed, for example, in Japanese Patent Application Laid-Open No.
No. 75669 has been proposed. In this method, a thermoplastic synthetic resin powder composition and a thermoplastic synthetic resin foamable powder composition are electrostatically applied to a mold VC, and then sintered and foamed to form a film to form a skin portion having a porous layer. Then, the foamable composition is injected and solidified to form a foam part. However, in this method, in order to produce a powdered composition, it is necessary to add various additives such as a blowing agent to the resin.
The temperature is adjusted to a temperature higher than the melting pour point of the resin and lower than the decomposition temperature of the blowing agent, and after thorough kneading, it is cooled at room temperature or with liquid nitrogen, etc. to a temperature of 220μ or less. It is necessary to grind until the Therefore, although this method can streamline the molding process, it complicates the manufacturing process of the material, so it is not necessarily preferable. Similarly, the manufacturing process for materials is still complex.

(Problems to be Solved and Attempted by the Invention) Therefore, an object of the present invention is to provide a powdered PVC composition that is easy to manufacture and that provides homogeneous and fine foam cells when sintered and foamed. be.

(Means for Solving the Problems) This object of the present invention is to use a pyrolytic foaming agent when producing a powder composition for sintering and foaming containing PVC powder, a plasticizer, and a pyrolytic foaming agent. This is achieved by adding it to the PVA powder as a plasticizer dispersion.

The PVC powder used as a component of the composition for sintering and foaming in the present invention is a homopolymer of vinyl chloride or a monomer copolymerizable with vinyl chloride of 50% or more by weight, such as vinyl acetate, ethylene, etc. It is a powder of a copolymer with a weight of less than 100 ml.

A mixture of these PVC and other synthetic resins,
Powdered resin mixtures having a VC portion of 50% by weight or more can be similarly used. The degree of polymerization of PVO is not particularly limited, and may be selected depending on the sintering conditions or usage conditions of the composition of the present invention, but usually the average degree of polymerization is 500 to 150.
0, preferably about 700 to 1000, is easy to use. Further, the particle size and particle size distribution of the powder are not limited either, and those having a mesh size of usually 40 to 300 mesh, preferably 80 to 200 mesh are easy to use.

As the plasticizer in the present invention, a general plasticizer for PVC is used. Specific examples include phthalate esters such as dioctyl phthalate and dibutyl phthalate;
Adipic acid esters such as dioctyl adipate and dibutyl adipate, naric acid esters such as tricresyl phosphate, oleic acid, trimellitic acid,
Examples include higher alcohol esters of organic acids such as cepatic acid. The amount of plasticizer added is usually 30 to 150 PER per 100 parts by weight of Pv0 (PHR). 3
If the PER is less than 0, it is necessary to increase the sintering temperature, which is not preferable due to problems with the thermal stability of the resin.
If R is exceeded, problems such as aggregation or blocking of the composition will occur when the ingredients are mixed and stirred.

The pyrolytic foaming agent used in the present invention is not subject to any restrictions as long as it decomposes at the sintering temperature and releases foaming gas (e.g. Nido-cl-based foaming agents (e.g. H, N'-dinitrosohentamethylenetetramine,
N,N'-dimethyl-N.

N'-dinitrosoterephthalamide, etc.), azo compounds (e.g. azodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate, etc.), sulfonyl hydrazides, benzenesulfonyl hydrazide*p+i''-oxybis(benzenesulfonyl hydrazides, )1) Luenesulfonyl hydrazide, other compounds (e.g. p-toluenesulfonyl 7-mycarbazide,
(trihydrazinotriazine, sodium bicarbonate), etc., and composite blowing agents that are a combination of two or more of these.

The type of plasticizer used as the dispersion medium of the pyrolytic foaming agent is not limited, but from the viewpoint of uniform dispersibility, kt, Pvc@
It is preferable to use the same plasticizer as the plasticizer used in the composition, and specific examples thereof are as described above.

The concentration of the pyrolytic blowing agent in the plasticizer dispersion is generally 5 to 9.
0 weight is considered to be regrettable. If it exceeds 90% by weight, the viscosity increases and homogeneous dispersion into the plasticizer becomes incomplete, and since the viscosity of the dispersion liquid is low in the case of 5wt. It aggregates, resulting in poor dispersion and a decrease in homogeneous foamability.

The method of preparing a dispersion of a heat-based blowing agent in a plasticizer in the present invention is not particularly limited. example! For example, the pyrolytic foaming agent and the plasticizer are mixed in advance using a ribbon blender, butterfly mixer, etc., and the mixture is forcibly dispersed using an ink mill. A method such as mixing with a plasticizer in a suitable mixer and forcibly dispersing it with an ink mill can be adopted. The pyrolytic foaming agent is preferably a plasticizer dispersion having an average particle size of 30 μm or less. Its average particle size is 60μ
Even if it is added to PVC as a dispersion liquid in a state exceeding 100%, uniform dispersion is insufficient and it is difficult to obtain homogeneous foam cells and a skin layer.

The resulting pyrolytic blowing agent dispersion is usually added to the PVC before adding the plasticizer. The number of parts added is usually PV
1 to 1 as the amount of thermal m-type blowing agent per 0100 PHR
0 PHR, preferably 15-5 PHR.

When adding a plasticizer after the pyrolytic blowing agent dispersion is uniformly dispersed in PVC, the temperature is preferably set to 80C or higher so that no aggregation or blocking of the composition occurs, generally 80C or higher. Below this temperature, the pyrolytic blowing agent is difficult to absorb into the PVC together with the plasticizer, resulting in a homogeneous foam cell T-
There are few effects to be gained.

Further, the addition and mixing of the pyrolytic blowing agent dispersion and the plasticizer to the pvC is carried out using a conventional mixer such as a Henschel mixer or a ribbon blender. The mixing time varies depending on the rotation speed, temperature, and mechanical conditions, but is usually 5 to 60 minutes.

In addition to PVC, plasticizers, and pyrolyzable blowing agent dispersions, heat stabilizers are usually used. Heat stabilizers that are solid at room temperature, such as barium stearate, zinc stearate, and stearic acid Metal soaps such as lead, inorganic acid salts such as dibasic lead phosphite, dibutyl fried malate, octyl tin malate, dibutyl tin mercaptide, polymerized organotin compounds; and composite stabilizers made by combining two or more types are used. In this case, it is preferable that these stabilizers also be made into a plasticizer dispersion. The method for preparing the dispersion is the same as the method for preparing the dispersion of a pyrolytic blowing agent in a plasticizer in the present invention.

In addition to the above-mentioned components, it is of course possible to use ordinary fillers, flame retardants, anti-aging agents, ultraviolet absorbers, stabilizing agents, pigments, dusting agents, etc., if desired.

The method of sintering and foaming the composition obtained according to the present invention in this manner is not particularly limited, and includes (rl) forming a foamed film by a fluidized dipping method, (2) applying the present composition on a smooth belt-shaped steel; (3) various molding methods such as powder foaming slush molding or powder foaming rotary molding by directly spraying the composition into a heating mold; is possible.

Molding conditions vary depending on the meltability of the composition, the decomposition temperature of the blowing agent, the shape of the molded product, etc., but are usually 15 (1 to 5007
: It takes about several seconds to about 50 minutes. If molded at a temperature exceeding 300C, abnormal foaming may occur or the thermal stability of pvcO may decrease.

The foamed sintered molded product obtained in this way has skin layers on the front and back surfaces of the molded product, and has uniformly fine foam cells, and generally has a thickness of several to several tens of meters. However, if you want to make the skin layer even thicker, you can first apply the required amount of non-foaming sintered composition to a heated mold, etc., and then apply the foamable sintered composition. A sintering method may be used, and a foamed molded product having a skin layer of a desired thickness can be obtained by this method. Moreover, if it is desired to further add a foam layer, it is of course possible to further line with foamable polyurethane or the like.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

Example A blowing agent (azodicarbonamide) was charged into a Hobart mixer, and then the blowing agent concentration was 251 (I), sos
(2) Dioctyl phthalate was added to give a concentration of 75% (2), and the mixture was sufficiently stirred to make a uniform dispersion.

Further, in the same manner, a dioctyl phthalate dispersion of a barium stearate/zinc stearate (70730) composite stabilizer having a concentration of 50% (particle size of 15 μm or less) was obtained.

Next, using the dispersion liquid, of the ingredients shown in the table (the number of parts added is parts by weight), except for the plasticizer (dioctyl phthalate) and the dusting agent (pvC> ?Put it into a Henschel mixer, mix once, and when the temperature rises to 100r, gradually add the plasticizer,
After heating up to 120C and cooling to 50C, a dusting agent was added and stirred, the mixture was taken out from the Henschel mixer to obtain powdered compositions (Experiment Nos. 1 to 9).

For comparison, a powdered composition was obtained in the same manner as above except that the blowing agent was directly put into the Henschel mixer (Experiment No. 10.11).

These compositions were spread on a 3 m thick flat mold with a skin pattern on the surface, heated at 270C for 7 minutes in an open gear, and left for 20 seconds. After that, the excess powder composition that did not adhere to the flat mold was removed, and the gear was opened again.
After heating and foaming for 30 seconds, the product was taken out from the gear open and cooled by immersing it in water. The foaming ratio, the state of the foamed cells, and the homogeneity of the foamed cells of the foamed molded product thus obtained were evaluated. The results are shown in the table.

In Experiment Nos. 1 to 9, which are examples of the present invention, foamed molded products having homogeneous and fine foam cells and a skin layer with a high expansion ratio were obtained, but Experiment No. 10.1, which is a comparative example.
In No. 1, the foamed cells were torn in various places and were non-uniform, and the skin layer was also partly torn in some parts, making it unsuitable for practical use.

Claims (1)

[Claims] When producing a powder composition for sintering and foaming containing vinyl chloride resin powder, a plasticizer, and a pyrolytic foaming agent, the pyrolytic foaming agent is added to the vinyl chloride resin powder as a plasticizer dispersion. A method for producing a vinyl chloride resin composition for sintering and foaming, characterized by: