JPS62285938A - Automobile side molding - Google Patents

Abstract

PURPOSE:To obtain an automobile matted side molding free from the formation of fish eyes, irregularities, etc., on the surface, by adding a plasticizer and a stabilizer each in a specified amount to a polymer component comprising partially crosslinked PVC and uncrosslinked PVC. CONSTITUTION:20-90pts.wt. partially crosslinked polyvinyl chloride having an average degree of polymerization of 400-1,500 and containing 1-50wt% crosslinked part insoluble in tetrahydrofuran is mixed with 80-10pts.wt. uncrosslinked polyvinyl chloride of an average degree of polymerization of 400-1,500. To 100pts.wt. obtained polymer component, 20-80phr of a plasticizer (e.g., dibutyl phthalate) and 1-8phr of a plasticizer (e.g., dimethyltin mercaptide) are added. The obtained flexible polyvinyl chloride composition is injection- molded to obtain the purpose automobile side molding. Component A can be obtained, for example, by copolymerizing a vinyl chloride monomer with an acrylate of a polyalcohol.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an automobile side molding made of a soft PVC composition by injection molding. In this specification, the units of quantity relating to formulations are by weight unless otherwise specified.

<Prior Art> Automobile side moldings serve as decoration as well as protection of the automobile body, and therefore have strict requirements regarding their appearance quality. In particular, when injection molding is performed using a soft PVC composition, it is difficult to obtain a completely smooth surface on the molded product due to variations in the amount of shrinkage in each part of the product, deformation during mold release, etc.
If it is glossy), minute irregularities will be noticeable and the appearance will be poor.

For this reason, a large amount of heavy calcium carbonate (20 to 40 phr) is blended into the soft PvC composition to make it semi-glossy or matte so that unevenness does not appear.

<Problem to be solved by the invention> However, when a large amount of heavy calcium carbonate is blended into a soft PVC composition, "fish eyes" caused by aggregates of heavy calcium carbonate occur on the surface of the molded product. It also tends to cause a significant decrease in physical properties such as tensile strength, oil resistance, and brittleness.

Means for Solving the Problems〉 Therefore, the present inventors have developed a method to create a matte side molding without incorporating double-weight calcium carbonate in such a large amount that it causes fish eyes or a significant decrease in physical properties. As a result of intensive development efforts to achieve this through injection molding, we came up with an automotive side molding with the following configuration.

In an automobile side molding made of a soft PVC composition by injection molding, TH is used as the polymer component of the soft PVC.
Contains 1 to 50 wt% of F-insoluble crosslinked portions t6F400 to
1500t7) 20 to 90 parts of partially crosslinked PVC, p4oo
~1500(7) Characterized by the use of a polymer blend consisting of a balance of non-crosslinked PVC.

Description of each component: The above-mentioned flexible PVC composition has (a) a polymer content of (
b) Plasticizer 20-80 phr, (c) Stabilizer 1-
8 phr, and further contains inorganic fillers such as calcium carbonate, talc, and clay, processing aids such as polyacrylate and polyester, pigments, etc., as necessary. In particular, it is desirable to incorporate a small amount (3 to 8 phr) of heavy calcium carbonate from the viewpoint of prevention of mold shrinkage and mixability of the composition.

(a) Partially crosslinked PVC, which is one of the polymer components, is:
For example, (1) those obtained by copolymerizing vinyl chloride monomer and one or more types of 7-acrylate ester e methacrylate ester/dimethacrylate ester of polyhydric alcohol (see JP-A-56-5843); Products obtained by copolymerizing a vinyl chloride monomer with one or more of diallyl adipate, diallyl fumarate, diallyl ether, triallyl cyanurate, triallyl isocyanurate, and triallyl trimellitate (Japanese Patent Application Laid-Open No. 1983-1973) (See Publication No. 80354).

Further, as the non-crosslinked PVC, a normal straight polymer or vinyl acetate copolymer is used, but a straight polymer is preferable from the viewpoint of heat deformation resistance and the like.

If the THF-insoluble crosslinked portion of the partially crosslinked PVC is less than 1 IIt%, the surface of the side molding cannot be made matte, and if it exceeds 50wt%, fluidity deteriorates and problems tend to occur in injection moldability. The content of the THF-insoluble crosslinked portion is preferably 10 to 40 wt%. In addition, when P of partially cross-linked PVC and non-cross-linked PvC is less than 400,
Difficulty in obtaining sufficient physical properties such as strength and thermal properties<,1
When it exceeds 500, fluidity deteriorates and problems tend to occur in injection moldability. Furthermore, if the blending ratio of partially crosslinked PVC in the entire polymer is less than 20 parts or more than 90 parts, uneven luster is likely to occur on the surface of the side molding.

(b) Plasticizers include phthalate esters such as di(2-ethylhexyl) phthalate (hereinafter abbreviated as "DOP"), dibutyl phthalate, and diisodecyl phthalate;
Linear dibasic acid esters such as dioctyl adipate and dioctyl sebacate.

In addition to phosphate esters such as tricresyl phosphate and triphenyl phosphate, one or a mixture of two or more of epoxy compounds such as trimellitate esters and polyesters are used.

Here, if the amount of plasticizer blended is less than 20 phr, soft PV
It does not fall within the range of composition C, and if it exceeds 80 phr, it becomes too soft and the shape retention ability required for the molding cannot be obtained.

(C) Barium and calcium as stabilizers.

Metal soaps such as 211X-based stearates such as zinc, organotin compounds such as dialkyltin mercaptides, dialkyltin malates, and dialkyltin laurates, lead salts, and their combination with niboxy compounds and sulfite esters. Used in combination with polyol, hindered phenol, etc. Here, if the amount of the stabilizer blended is less than 1 phr, the blending effect (mainly thermal stability) cannot be obtained, and even if it exceeds 8 phr, the blending effect will not increase much and it is economically wasteful.

The above-mentioned soft PVC composition is stirred and mixed, and then kneaded and granulated using a twin-screw kneading extruder or the like to obtain an injection material.

<Actions and Effects of the Invention> The automobile side molding of the present invention has a polymer content of TH
7400~ containing 1~10wt% of F-insoluble crosslinked parts
20-90 parts of 1500 partially cross-linked PVC and P400-1
By injection molding a soft PVC composition, which is a polymer blend consisting of 500% non-crosslinked @PVC9, as will be demonstrated in the examples below, a matte surface with no visible surface irregularities can be obtained. Moreover, it has a good appearance quality without causing fish eyes and without significant deterioration of physical properties.

The reason for this is not necessarily clear, but it is presumed that the matte surface of the product causes light to be diffusely reflected, making it difficult to notice that the surface is uneven.

<Example> Hereinafter, the present invention will be explained in detail based on examples.

Using the material obtained by mixing, mixing, and granulating the soft PVC compositions with the formulations shown in Table 1, the shape shown in Fig. 1 (440 m
injection molding (conditions: nozzle temperature 180°C,
Injection pressure: 45 kgf/crn', mold temperature: 50°C)
did.

Then, each molded product was visually evaluated for (1) degree of unevenness, (2) gloss, and (2) frequency of fish-eye occurrence.

From the results shown in Table 1, each example has a matte appearance with no visible surface irregularities and no fish eyes, while the comparative example in which the polymer is only non-crosslinked PvC has a matte appearance. Surface irregularities can be confirmed in the case of the presence (Comparative Examples 1 and 4), and when the amount of heavy calcium carbonate is increased,
It can be seen that fish eyes are likely to occur when the color is semi-glossy or matte (Comparative Examples 2-3-5 and 6).

Patent applicant 1j knee=’1

Claims (1)

[Scope of Claims] Soft polyvinyl chloride (hereinafter referred to as "PVC") having the following requirements:
A side molding for an automobile, characterized by being injection molded with a composition (abbreviated as ""). (a) The flexible PVC composition contains 20 to 80 phr of a plasticizer and 1 to 8 phr of a stabilizer based on the polymer content. (b) The polymer component is tetrahydrofuran (hereinafter "
Average degree of polymerization (hereinafter abbreviated as "@P@") containing 1 to 50 wt% of insoluble crosslinked moieties (abbreviated as "THF") 400 to 15
00 partially crosslinked PVC 20-90 parts by weight @P@400
Polymer blend consisting of ~1500% non-crosslinked PVC balance.