JPH01215845A - Vinyl chloride resin composition - Google Patents

Abstract

PURPOSE:To provide a resin composition for powder molding, free of mold staining, easily releasable from a mold and excellent in fogging resistance, by mixing a vinyl chloride resin with a plasticizer, a salt of a specified acid and a polyacrylic acid compound in a specified mixing ratio. CONSTITUTION:A powdery vinyl chloride resin composition is produced by mixing 100pts.wt. vinyl chloride resin (A) with 0.1-5pts.wt. zinc or barium salt (B) of an acid selected from among a 5-8C fatty acid, an aromatic organic acid and naphthenic acid (e.g., zinc caprylate or barium benzoate), 0.1-10pts.wt. polyacrylic acid compound (C) (e.g., tin-containing polyethyl acrylate) and necessary additives (D) such as a plasticizer (e.g., tri-n-octyl trimellitate) and a stabilizer. This resin composition can be suitably used for, for example, powder flash molding and powder rotation molding for molding a facing of, e.g., an automobile interior furnishing.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is mainly concerned with powder slush molding or powder rotation molding for molding skin materials such as crash pads, console boxes, headrests, meter covers, etc. as automobile interior materials. The present invention relates to a vinyl chloride resin composition for use.

(Conventional technology) In recent years, surface materials for automobile interiors such as crash pads, console boxes, headrests, and meter covers have been required to be lighter, more complex in design, and have a more luxurious feel, such as leather tie patterns and stisochi patterns. It is becoming more and more common.

Conventionally, these skin materials have been made of vinyl chloride resin (hereinafter referred to as PVC).
They were vacuum-formed soft sheets made of a blend material of ABS resin or NBR, and slush-molded or rotary-molded products of PVC paste sol. In recent years, slush molding or rotary molding using PVC powder has also come to be applied to the molding of automobile interior materials, and has been attracting attention.

However, although it is possible to reduce the weight of vacuum-formed products to a certain extent, they not only cause squeezing during the molding process and cannot be provided with a Stisochi pattern, but also cannot be provided with complex shapes such as deep undercuts. In addition, generally only molded products with a hard feel can be obtained, and molded products with a soft and high-quality feel cannot be obtained.

On the other hand, a sol-molded article made of PVC paste can impart a soft feel, and can also be formed with a squeeze pattern, stain pattern, undercut shape, etc., and can provide a molded article with a high-class feel. However, sol molding tends to cause flow marks and stringing phenomena, and problems remain in that the smoothness of the back surface is poor and uneven thickness tends to occur, and the molded sheet inevitably becomes thick.

In order to solve these problems, powder molding methods have recently begun to be used for molding skin materials for automobile interior materials.

Powder molding is a general term for molding methods that produce molded products by sintering raw resin powder, and typical molding methods include fluidized immersion, injection, electrostatic coating, and rotational molding. The powder molding methods suitable for molding the skin of automobile interior materials are the rotary molding method and the slush molding method.

Such powder rotary molding method or powder slush molding method generally involves supplying a large amount of powdered resin to a mold heated to 200°C or higher, welding the powdered resin to the inner surface of the mold, and then removing the excess powdered resin. This method completely melts the resin that has been collected and welded to the mold surface.

As can be seen from the characteristics of the powder molding method, the powder composition used in such powder molding methods must have excellent powder fluidity and moldability, and must maintain physical properties appropriate to the intended use. .

PVC powder compositions to be subjected to powder compaction are generally PVC
Mixing ingredients such as resins, plasticizers, stabilizers, and pigments are blended using a high-speed stirring blender equipped with a heating jacket.
It is produced by dry blending up to ~150°C and then adding fine particle size fillers and fine particle size PVC powder to improve powder flowability. Therefore, due to this manufacturing method, compounding agents such as stabilizers inevitably adhere to the outside of PVC particles with a particle size of about 100 microns, which can be easily inferred from the characteristics of the powder molding method. However, there is an increased chance that the compounding agent etc. will come into direct contact with the mold. As a result, as the number of molding cycles increases, compounding agents and the like accumulate on the mold, and the mold gradually becomes contaminated.

As such mold contamination progresses, the apertures engraved on the mold surface gradually become filled in, causing gloss to appear on the surface of the molded skin material. The occurrence of such cracks is extremely undesirable from a safety point of view, especially when used as an interior material for an automobile, as it obstructs the driver's view due to the reflection of incident light.

To solve this problem, during molding, after a certain number of molding cycles, the mold is periodically cleaned with an alkaline cleaning solution, acid cleaning solution, or organic solvent, and if the mold is heavily contaminated,
Since these cleaning solutions cannot completely remove the contaminants, a mechanical method such as sandblasting must be applied.

Although these methods are certainly effective in removing mold contaminants, they may reduce productivity due to cleaning, and if mechanical methods are frequently used, mold wear may occur. This will shorten its lifespan.

In addition, the main cause of mold contamination is PVC for powder molding.
Since the stabilizer in the composition is a compounding agent such as barium stearate, zinc stearate, calcium stearate, etc., there is also a method of using a stabilizer with high compatibility with Pvc as a compounding agent. For example, when using a fatty acid metal soap stabilizer, the alkyl group of the fatty acid has a short carbon number of about 5 to 8 (JKAI 62-2706.45).

However, with this method of increasing the compatibility of compounding agents with PVC, when demolding the molded product from the mold, the releasability between the mold and the molded product deteriorates, and a large amount of force is required during demolding. Because it is necessary,
This may cause deformation or, in extreme cases, damage to the molded product. Therefore, when using highly compatible compounding agents, an extra step is required in which the mold must be coated with a release agent such as silicone or fluorine, which reduces productivity. become.

In addition, in order to improve demoldability, we add mold release improvers (lubricants) with low boiling points, such as liquid paraffins that do not cause mold contamination, and lower alcohol esters of fatty acids such as butyl stearate, to the compound. There is a way to do that. However, when such low boiling point substances are included in the composition, these volatile components tend to gradually volatilize from the resulting molded product, causing a so-called fogging phenomenon in which the window glass of an automobile becomes foggy.

(Problems to be Solved by the Invention) Therefore, as a result of repeated studies in order to solve the problems of the prior art, the present inventors have developed a specific formulation system using PVC.
The present inventors have discovered that mold contamination and demolding properties can be significantly improved by adding the compound to the composition of the present invention.

(Means for Solving the Problems) According to the present invention, in a powder composition formed by dry blending a vinyl chloride resin, a plasticizer, etc., the number of carbon atoms in an alkyl group is 5-8
0.1 to 5 parts by weight of a zinc salt or barium salt of an acid selected from fatty acids, aromatic organic acids, and naphthenic acids, and 0.1 to 10 parts by weight of a polyacrylic acid compound. A vinyl chloride resin composition is provided.

It becomes a raw material component of the first component metal salt (hereinafter sometimes referred to as metal soap) used in the present invention.

As fatty acids having an alkyl group having 5 to 8 carbon atoms,
Examples include hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, etc., and aromatic organic acids include phenol, benzoic acid, salicylic acid, phthalic acid, etc.

These metal soap stabilizers generally have a low molecular weight,
It has good compatibility with PVC, and has high thermal stability due to the high metal content.However, although the compatibility is good, the lubricity is low, so the heat resistance is not necessarily practical due to the generation of frictional heat during processing. It has not been used much in the past because it does not have any sexual characteristics.

However, the present inventor focused on the fact that no shearing force is applied during processing in powder molding, and therefore no frictional heat is generated, and developed these phase stabilizers as a metal soap-based stabilizer for PVC that does not cause mold contamination. It has been found that it is sufficient to use a highly soluble zinc salt or barium salt of a fatty acid, an aromatic organic acid, or a naphthenic acid having an alkyl group having 5 to 8 carbon atoms.

The metals used in these metal soaps used in the present invention are zinc and barium. In addition to the above-mentioned organic acids, the acid radicals of metallic soaps may of course be derivatives of these, but from the viewpoint of industrial availability and economic efficiency, especially fatty acids such as 2-ethyl are preferred. Among the xoic acid and aromatic organic acids, benzoic acid and naphthenic acid are preferred.

In addition, fatty acids having an alkyl group having 9 or more carbon atoms, such as stearic acid, valmitic acid, lauric acid,
Metallic soap stabilizers such as oleic acid and lysyllic acid are
It has good thermal stability against VC, and is often used in extrusion molding, calendar molding, etc. because it can add lubricity.
In powder molding, since there is no compatibility, demoldability is good, but plate-out onto the mold surface contaminates the surface.

The amount of zinc-based stabilizer and barium-based stabilizer used in the present invention is such that the metal weight ratio of zinc and barium is 5:1, including the amount of zinc and barium of other optional stabilizers.
Or 1 to 5. If the ratio of zinc increases beyond this range, the thermal stability will be extremely poor, and if the ratio of barium increases, there will be a disadvantage that the composition will be initially colored and the composition will have a strong yellowish or reddish tinge.・The amount added is 0.1 parts by weight per 100 parts by weight of PVC.
~10 parts by weight. If it is less than 0.1 parts by weight, the thermal stability effect will be low, and if it exceeds 10 parts by weight, there is a risk that it will ooze out over time into the obtained molded product (skin material) even if no problems occur during molding.

Further, in the present invention, it is necessary to add a polyacrylic acid compound.

The polyacrylic acid compound referred to herein is a polymer of acrylic ester and methacrylic acid alkyl ester, and is represented by the following formula, (R is an alkyl group such as methyl, ethyl, butyl, or 2-ethylhexyl, n is 50
It is preferably 3 to 30 below. ) and contains one or more of the following groups in the molecule.

R'R'OR' 1 1 II 1-COoII
, -COO5nOR, -COO5nOCR, -CO
O5nSR"R'R'R'
CR',R'': Preferably long-chain hydrocarbon residues) Such polyacrylic acid compounds have a portion in the molecule that is compatible with PVC and a portion that is incompatible with PVC. It functions as a mold release agent in the mold without contaminating the mold.

That is, the metal soaps used in the present invention described above have high compatibility with PVC and therefore cannot function as effective mold release agents.

Therefore, it is necessary to separately add a substance that has a mold release effect, but substances that have the function of a mold release agent usually cause mold contamination. However, since the polyacrylic acid compound having this structure contains a main chain portion that is highly compatible with PVC and a group that is incompatible with it, it functions extremely effectively as a mold release agent with almost no mold contamination. Furthermore, since this compound is a polymer, no fogging phenomenon occurs.

The amount of the polyacrylic acid compound added is 0.1 to 10 parts by weight per 100 parts by weight of PVC. If it is less than 0.1 parts by weight, there is almost no mold release effect, and if it exceeds 10 parts by weight, it is undesirable in terms of mold contamination.

The PVC used in the present invention is a homopolymer of vinyl chloride made by suspension polymerization, bulk polymerization, and emulsion polymerization, or a copolymer of vinyl chloride and common comonomers such as ethylene, propylene, vinyl acetate, etc. It is a combination. A mixture of two or more of these polymers may also be used.

Plasticizers used in the present invention are not particularly limited, but include phthalic acid esters such as diisodecyl phthalate, dialkyl tucrate whose alkyl group has 9 to 11 carbon atoms, tri-n-octyl trimellitate, Tory 2
-Trimellitic acid esters such as ethylhexyl trimellitate, tridecyl trimellitate, and trialkyl trimellitate whose alkyl group has 7 to 11 carbon atoms are used. Further, epoxy plasticizers, polyester plasticizers, etc. can also be used, and it is of course possible to use these plasticizers in combination, and the plasticizers are not limited to those listed here.

Furthermore, the PVC composition of the present invention may contain an antioxidant, an ultraviolet absorber, a filler, a pigment, etc., as necessary, in addition to a plasticizer and a stabilizer.

(Effects of the Invention) According to the present invention, a PvC composition for powder molding that does not cause mold contamination, is easily demolded, and has excellent fogging resistance can be obtained.

(Example) The present invention will be described in more detail with reference to Examples below. Note that parts and percentages in Examples and Comparative Examples are based on weight unless otherwise specified.

The average molecular weight is 80 using a Henschel mixer with a capacity of 20β.
0 pvc <Nippon Zeon, Zeon 103EP-8)
After heating and stirring, when the resin temperature reached 80"C, a plasticizer and a specified stabilizer, pigment, etc. dispersed in the plasticizer were added, and the resin was heated in a dryer until the resin temperature reached 125"C. I knobbed. Thereafter, heating was stopped, and when the resin temperature reached 50° C., fine particles of PVc (Zeon 131C, manufactured by Nippon Zeon) were added, uniformly dispersed, and then taken out.

All of the powders obtained were smooth and had good fluidity. Table 1 shows the formulations of the invention examples and comparative examples.

The powder composition thus obtained was subjected to the following tests. The results are shown in Table 2.

■ Mold contamination 10100 x 200 Ni electroformed flat mold at 250℃
5. Sprinkle the above powder composition excessively, and
After seconds have elapsed, excess powder is removed from the mold, and the mold is placed in gear open at 350°C for 30 seconds. After that, it is taken out and immersed in water to cool down, and then the sintered sheet attached to the mold is peeled off. This operation is repeated 50 times, and the degree of surface contamination of the Ni electroforming drawing die is observed according to the following criteria.

◎　No stains are observed.

○ Almost no dirt.

△　Slightly dirty.

× There is dirt.

XX　Significant dirt.

■ Demovability The ease with which the sintered sheet can be removed from the mold during the above operations is judged as follows.

○ Almost no force is required to release from the mold.

△ Slight force is required to release from the mold.

× Quite strong force is required to release the mold.

Claims (1)

[Claims] In a powder composition formed by dry blending a vinyl chloride resin, a plasticizer, etc., based on 100 parts by weight of the vinyl chloride resin, from fatty acids whose alkyl groups have 5 to 8 carbon atoms, aromatic organic acids, and naphthenic acids. A vinyl chloride resin composition comprising 0.1 to 5 parts by weight of a zinc salt or barium salt of a selected acid and 0.1 to 10 parts by weight of a polyacrylic acid compound.