JPS6198750A - Plastisol for foam molding - Google Patents

Abstract

PURPOSE:Plastisol for foam molding having improved releasability, mechanical foaming properties, etc., obtained by dispersing PVC paste resin of mixture for isocyanate crosslinking and not for crosslinking in a specific ratio into a liquid plasticizer and adding a compounding agent such as polyisocyanate, etc., to the mixture. CONSTITUTION:100 pts. wt. paste resin consisting of mixture of paste resin for isocyanate crosslinking and one not for crosslinking in a weight ratio of 30/70-70/30 is dispersed into 50-110 pts. wt. liquid plasticizer [e.g., di(2- ethylhexyl) phathalate, etc.], and the dispersion is blended with approximately chemical equivalent polyisocyanate, 1-5 pts. wt. foam stabilizer, 1-5 pts. wt. stabilizer, and other compounding agents.

Description

Detailed Description of the Invention <Industrial Application Field> This invention is a foam molding process in which a paste resin of vinyl chloride resin (hereinafter referred to as rPVcJ) is dispersed in a liquid plasticizer, and contains a stabilizer and other compounding agents. Regarding plastisol for use.

<Prior art> Conventionally, when foam molding of the above type of plastisol is carried out using a mold, plastisol 1 is supplied to a mixer 3 with a pump (snake type) 2, as shown in the model diagram of Fig. 1. , mechanically foam by stirring while supplying air, inject into the cavity 6 of the mold 5 through the injection gun 4, and heat the mold (160 to 220' (1!XIO to 60 minutes) to form the paste resin. This process was carried out by completely dissolving plastisol in a burnable agent and then cooling it to solidify the plastisol.Recently, molded products obtained in this way have been developed with the aim of improving mechanical strength such as abrasion resistance and heat resistance. The use of isocyanate crosslinking paste resins that have excellent heat resistance, weather resistance, etc. is being considered.

<Problems to be Solved by the Invention> However, when the above-mentioned foam molding is performed using this crosslinking paste resin, there are the following problems, and it has not been put to practical use yet.

(a) Crosslinking paste The crosslinking agent (polyisocyanate) added to crosslink the resin acts as an adhesive between the metal and PVC, and when the mold is heated, the molded product is transferred to the cavity surface of the mold. This will make it difficult to release the mold.

(b) Since the paste resin for crosslinking contains polar groups such as water-unfriendly groups, the viscosity increases due to association, and the ability to insert into a mold and mechanical foamability decreases.

<Means for Solving the Problems> The foaming plastisol of the present invention is made by dispersing a PvC paste resin, which is a mixture of incyanate crosslinking and non-crosslinking (normal) resin in a certain composition range, in a liquid plasticizer. The above-mentioned problems are solved by containing approximately chemical equivalents of polyisonate, foam stabilizer, and other additives.

Each configuration of the writing means will be explained in detail. Hereinafter, "1 part" in the compounding amount refers to "1 part by weight" (1) Paste resin...for isocyanate crosslinking: for non-crosslinking = 30
It is a mixture having a composition (blend ratio) of /70 to 70/30 (weight ratio).

Here, the paste resin is obtained by emulsion polymerization or emulsion suspension polymerization of vinyl chloride alone or vinyl chloride and other vinyl monomers (vinyl acetate, etc.) and has a particle size of 10-5 to 10.
- Isocyanate which is a polymer or copolymer in the form of fine particles of 7 cm, which is only slightly soluble (only the surface layer of the particles) in a liquid plasticizer at room temperature and capable of forming an organosol (i.e. plastisol). For crosslinking, for non-crosslinking, that is, normal paste resin, O is added at the polymer end.
It has an H group introduced.

In the composition of this paste resin mixture, if the amount of isocyanate crosslinking is in excess of the above range, the molded article and the mold tend to adhere to each other when the mold is heated, and the viscosity of the plastisol increases, which is undesirable. On the other hand, if the amount of isocyanate for crosslinking is too small, it will not be possible to improve the mechanical strength such as abrasion resistance of the molded product.

(2) Monoplasticizer: di(2-ethylhexyl) phthalate, dibutyl phthalate, dinonyl phthalate,
Ethralate phthalates such as diisodecyl phthalate and diisodecyl phthalate, resin group dibasic acid esters such as dioctyl adipate, diisodecyl adipate, and dioctyl sebacate, trioctylphosphny 1, triphenyl phosphate? A phosphoric acid ester type, an epoxy type such as epoxidized soybean oil, a polyester type such as polypropylene adipate, and an aromatic carboxylic acid type such as trioctyl trimellitate may be used alone or in combination of two or more types. Among these, from the viewpoint of low-fogging properties and fluidity of plastisol, heptatarate-based alcohols having 9 or more carbon atoms are preferred, as they have low volatility and excellent viscosity stability.

Incidentally, the blending amount is usually 50 to 110 parts per 100 parts of the paste resin mixture. The paste resin is dispersed in the plasticizer using conventional mixing means, such as a Hobart type mixer or a large oak continuous mixer.

(3) Polyisocyanate: The polyisonates listed in (■) below can be used, but since the NCO group has high reactivity, they are usually combined with phenol, acetoacetate, cyclohexanone oxime, thiophenol,
Blocked German cyanate whose NCO group is protected with an aliphatic alcohol or the like is used. Furthermore, it is desirable that it is non-volatile and non-yellowing.

■Hexamethylene diisonanate, xylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, sulfonyl diisocyanate, dicyclohexylisopropylidene-4,4' -Diisocyanate (non-yellowing), tolylene diisocyanate (TD Engineering), diphenylmethane-4,4'-diisocyanate, TDI trikeitai, trimethylpropane-1-
Methyl-2-isocya/'-4-carbamate, polymethyleneborifninyl isocyanate, 3,dimethoxy-4,4'-diphenyl diisocyanate.

If this polyisocyanate greatly exceeds the chemical equivalent, the excess polyisocyanate will act to bond the molded product and the mold, and conversely, if the polyisocyanate is insufficient, sufficient crosslinking will not occur and the molded product will have poor wear resistance, etc. No improvement in mechanical strength can be expected.

(4) Foam stabilizer: Organic surfactants such as sodium alkylbenzenesulfonate and potassium alkylbenzenesulfonate, or silicone oils such as polydimethylsiloxane and polymethylphenylsiloxane are used. The blending amount is usually 1 to 5 parts per 100 parts of the paste resin mixture.

(5) Stabilizers: Metal soaps such as lead stearate, notrium stearate, cadmium stearate, zinc stearate, tin-based soaps such as dibutyltin dilaurate, dibutyltin maleate, organotin mercaptide, organotin sulfonamide, etc. , tribasic lead sulfate, dibasic lead phosphite, and tribasic maleic lead are used. The blending amount is usually 1-y5 parts per 100 parts of the paste resin mixture.

(6) Other additives: Although not essential, there are fillers such as calcium carbonate and clay, lubricants such as higher fatty acid derivatives, and pigments for coloring.

(7) Mechanical foam molding with plastisol: The platisol of the present invention is molded in the same manner as conventional molding, but when the mold is heated, the paste resin mixture is completely dissolved in the plasticizer and simultaneously crosslinked.

(8) Fields of application of plastisol...The plastisol of this invention can be applied not only to mechanical foaming but also to chemical foam molding containing a foaming agent, and the applicable products include heat resistance, weather resistance, and abrasion resistance. There are automotive interior parts such as steering wheels, safety pads, lids, console boxes, and assist grips that require

<Examples> Hereinafter, the present invention will be described in more detail based on Examples.

Plastisols of Examples (comparative examples) were prepared by stirring the mixtures shown in Table 1 using a Hobart mixer (however, in the case of the peel test, no silicone oil was added).

(1) Viscosity The viscosity of each plastisol at room temperature was measured using a BM viscometer (manufactured by Tokyo Keiki Co., Ltd.). In addition, Comparative Example 3.4
When "P-510" or "P-470" was set at 100 parts and polyisocyanate was set at 0 parts, the viscosities were 2900 cP and 1400 cP, respectively.

(2) Peeling test: Apply each plastisol on a 3cm x 14cm rectangular iron plate (coating amount: 0.1 g10w'), 180℃XlS
After heating in an oven for 24 hours at 23° C. and cooling for 24 hours, a 90' peel test was conducted to determine the adhesion of PVC to metal.

(3) Tensile test Using each plastisol obtained above, a sheet-like molded product was obtained by the method described above (heating condition: 180°C x 15 minutes, cooling condition: 23°C x 24 hours), and from this molded product, a dumbbell-shaped ( J.I.
S3) was punched out and JISK-6 in a 130℃ atmosphere.
It was carried out in accordance with 301. The results of each of the above tests are shown in Table 1 and Figures 2 to 4. Comparative examples in which the ratio of crosslinked and non-crosslinked paste resins is not within the range of the present invention have poor viscosity, peel strength, or mechanical properties. If any of the strength (tensile test) items are unsuitable, if you look at it comprehensively, it will fail if strength is required for the molded product, if vacuum forming is performed as secondary molding, etc. .

*l), *2), *3) Product name Manufactured by Monsando Co., Ltd. *2) 75-1500. *3) p=3700 rating 20・
...Pass,
By using a mixture of PVC paste resin for isocyanate crosslinking and for specific crosslinking with a constant composition, the following effects are achieved.

(a) Even if polyisocyanate is added as a crosslinking agent, the metal and the molded product do not adhere to each other when the mold is heated, and the mold releasability is good, although the reason is unknown.

(b) By mixing a predetermined amount or more of a non-crosslinking paste resin for crosslinking, the viscosity is almost the same as that of the non-crosslinking paste resin (in some cases, it becomes smaller), and the injectability into molds and mechanical foaming are improved. The quality does not decrease.

[Brief explanation of drawings]

Figure 1 is a schematic illustration of mechanical foam molding using PVC plastisol, and Figures 2 to 4 show the viscosity, ! ! It is a graph diagram showing test results of peeling strength and tensile (elongation). 1... Plastisol, 2... Pump, 3... Mixer, 4... Injection gun, 5... Mold. Nail 2WI For Song Dynasty → For non-cross-linking Figure 8 Figure 4 For cross-linking 4-S For non-cross-linking

Claims (1)

[Scope of Claims] A plastisol for foam molding comprising a paste resin of vinyl chloride resin dispersed in a liquid plasticizer and containing a foam stabilizer, a stabilizer, and other compounding agents, wherein the paste resin is used for isocyanate crosslinking. : For non-crosslinking = 30/70 to 70/3
1. A plastisol for foam molding, which is a mixture with a weight ratio of 0 (weight ratio), and further contains approximately a chemical equivalent of polyisocyanate as a crosslinking agent.