JPH0657760B2 - Pellet-shaped flexible vinyl chloride resin composition used for extrusion molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has dense and uniform independent foam cells by an extrusion foam molding method, has a foaming ratio of 1.3 to 3.5 times, and has good surface smoothness. The present invention relates to a pellet-shaped soft vinyl chloride resin composition for foaming, which gives a soft vinyl chloride foamed molded article with good reproducibility. More specifically, automotive parts such as glass run channels, weather strips, interior cushioning materials, side moldings, building material parts such as anti-slip and edging of furniture, sheet-shaped and tube-shaped, and various irregular sound insulation,
Soft vinyl chloride resin such as anti-vibration or heat insulating material, sealing material, cushion material, polyurethane, EPDM
A flexible vinyl chloride-based extrusion foam-molded product that has a dense and uniform independent foaming cell, a foaming ratio of 1.3 to 3.5 times, and good flatness smoothness that can be suitably used in the field where The present invention relates to a pellet-shaped soft vinyl chloride resin composition for foaming, which gives good reproducibility.

[Prior Art] As a method for producing a vinyl chloride foam by extrusion foaming, there are a method using an evaporative foaming agent and a method using a decomposable foaming agent.

The method of using a decomposing type foaming agent is often used for the production of low-foamed products because it has the advantage that it can be used by simply modifying the extruder that has been used in the past and that the process is simple. .

However, adding a plasticizer to the vinyl chloride resin,
Even if a decomposition type foaming agent is added to a so-called soft vinyl chloride resin composition to produce a product by extrusion foam molding, a foam molded product having dense and uniform independent foam cells and good surface smoothness is obtained. Only foaming ratio less than 1.2 times can be obtained.

In addition, if a normal kneading temperature is applied during the production of the pelletized compound to be subjected to extrusion foam molding, the amount of the foaming agent in the compound cannot be strictly controlled because the foaming agent decomposes, and therefore the expansion ratio is stable. It was not possible to obtain a compound with good reproducibility
If the kneading temperature is lowered in order to suppress the decomposition of the foaming agent, there is a problem in that the compounding becomes difficult due to insufficient kneading.

As a method for solving the problems at the time of extrusion foam molding and the problems at the time of compound production, it is well known that a method of adding a processability improving agent is effective to some extent. For example, JP-A-51-5371 and JP-A-58-52327
As disclosed in each of the publications, the effect is recognized in the two-stage method in which a sheet is first molded and then foamed in a foaming furnace.

However, in the so-called extrusion foam molding method in which foaming is performed at the die outlet during extrusion molding, even if a commonly used copolymer containing methyl methacrylate as a main component and a specific viscosity of 1 to 2 is added, In addition, it is not possible to obtain a foamed molded article having excellent uniformity and independence of foam cells, a foaming ratio of 1.3 times or more, and extremely good surface smoothness with good reproducibility, and a problem during compound production cannot be solved.

The market demand for a soft vinyl chloride compound for extrusion foaming emphasizes not only the expansion ratio but also the stability of the expansion ratio, and it is desired to solve the above problems.

[Problems to be Solved by the Invention] The present invention provides a pellet-shaped soft vinyl chloride resin composition for foaming used in extrusion molding according to the prior art (1) Pellets at a kneading temperature at which decomposition of a decomposable foaming agent can be suppressed. When it is attempted to produce a solid compound, the kneading becomes insufficient and the production becomes difficult, so it is unavoidable to knead at a certain high temperature, and the amount of the foaming agent in the compound cannot be strictly controlled, resulting in As the expansion ratio,
Stable and reproducible foam molded products cannot be manufactured. (2) Extruded foam molding method has dense and uniform independent foam cells, good surface smoothness, and expansion ratio of 1.3 times. It is intended to solve the above-mentioned problem that a soft foam molded article cannot be obtained.

[Means for Solving Problems] The present invention is based on 100 parts of vinyl chloride resin (parts by weight, the same applies hereinafter) and 100 ml of a benzene solution containing 0.4 g of a copolymer containing methyl methacrylate as a main component. The specific viscosity measured at 30 ° C of 2.5 or more and the glass transition temperature of 85 ° C or less are compounded with 1 to 30 parts of a methyl methacrylate copolymer, 20 to 200 parts of a plasticizer, and 0.5 to 10 parts of a decomposable foaming agent. With regard to the pellet-shaped foamable soft vinyl chloride resin composition used for extrusion molding, the use of such a composition makes it possible to increase the expansion ratio of the soft vinyl chloride-based extrusion foam-molded product to 1.3 times or more. In addition, the independence and uniformity of the foam cells can be improved, and a foam-molded article with good surface smoothness can be obtained.

[Example] The vinyl chloride-based resin used in the present invention is not only a vinyl chloride resin obtained by homopolymerizing a vinyl chloride monomer, but also a vinyl chloride-based copolymer containing 85% or more (by weight%, the same below) of vinyl chloride It is a concept including a resin and a partially crosslinked vinyl chloride resin containing 85% or more of vinyl chloride and having a gel content of 5 to 90% insoluble in tetrahydrofuran.

Specific examples of the vinyl chloride-based copolymer resin include vinyl chloride-alkyl vinyl ester copolymer resins such as vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-ethylene copolymer resins and vinyl chloride-propylene copolymer resins. Vinyl chloride-olefin copolymer resin, vinyl chloride-butyl acrylate, ethyl acrylate and other acrylic acid alkyl ester copolymer resins, vinyl chloride and methyl methacrylate, ethyl methacrylate and other methacrylate alkyl ester copolymers Examples thereof include polymer resins and copolymer resins of vinyl chloride and alkyl vinyl ether.

Specific examples of the partially crosslinked vinyl chloride resin include, for example, a diallyl compound such as diallyl phthalate as a crosslinking agent during the production of the vinyl chloride resin or vinyl chloride copolymer resin, and a diglycol such as polyethylene glycol di (meth) acrylate. Examples thereof include partially crosslinked butyl chloride resins obtained by using (meth) acrylate compounds and the like.

Furthermore, these resins may be used alone or in combination of two or more kinds.

The vinyl chloride resin preferably has an average degree of polymerization of 600 to 4500, more preferably 1000 to 3200. If the average degree of polymerization is less than 600, it tends to be difficult to mix and dry up the plasticizer, and if the average degree of polymerization exceeds 4,500, it tends to be difficult to sufficiently knead.

The methyl methacrylate-based copolymer used in the present invention is a copolymer containing methyl methacrylate as a main component, that is, 50 to 95%, and 100 ml of a benzene solution containing 0.4 g of the copolymer at 30 ° C. It has a specific viscosity of 2.5 or more, preferably 2.5 to 6.0, and a glass transition temperature of 85 ° C. or less. When the specific viscosity is less than 2.5, the uniformity, independence and surface smoothness of the cells of the foamed molded product produced from the obtained composition are not sufficiently improved, and the effect of improving the expansion ratio is not sufficiently obtained. Moreover, the kneading property at the time of producing the pelletized compound is not sufficiently improved. The glass transition temperature must be 85 ° C. or lower in order to further improve the kneading property during the production of the pelletized compound.

Examples of the components other than methyl methacrylate of the methyl methacrylate-based copolymer include ethyl acrylate, butyl acrylate, propyl acrylate, and acrylic acid-2.
-Acrylic acid esters such as ethylhexyl, and methacrylic acid esters such as ethyl methacrylate, butyl methacrylate, propyl methacrylate, and 2-ethylhexyl methacrylate (excluding methyl methacrylate). These components may be simply copolymerized or graft polymerized, and a small amount of the above-mentioned crosslinking agent may be copolymerized during the polymerization.

The methyl methacrylate copolymer used in the present invention is 1 to 30 parts, preferably 3 to 2 parts per 100 parts of vinyl chloride resin.
5 parts, particularly preferably 5 to 20 parts are used. The amount is 1
If it is less than 10 parts, the expansion ratio will not be sufficiently improved, and if it exceeds 30 parts, the foamed molded product will be hard and the cost will be high, such being undesirable. The methyl methacrylate-based copolymer may be used alone or in combination of two or more kinds.

The plasticizer used in the present invention is a component added to give a molded article flexibility, rubber feel, etc., and is used in an amount of 20 to 200 parts, preferably 30 to 160 parts, per 100 parts of the vinyl chloride resin. It If the amount exceeds 200 parts, it will not dry up,
In addition, the heat distortion resistance of the molded product and the independence of the cells decrease, and the molded product becomes sticky, which causes many practical problems in processing, which is not preferable. If the amount used is less than 20 parts, it is not preferable because the molded product cannot be sufficiently imparted with flexibility and rubber feel.

Specific examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, alkyl esters of aromatic polybasic acids such as trioctyl trimellitate, dioctyl adipate, alkyl esters of aliphatic polybasic acids such as dioctyl azelate, tris. Examples include phosphoric acid alkyl esters such as cresyl phosphate, and commonly used plasticizers such as polyester plasticizers and epoxy plasticizers. These may be used alone or in combination of two or more kinds. .

Specific examples of the decomposing type foaming agent used in the present invention include barium azodicarboxylate, azodicarbonamide, 4,4'-oxybisbenzenesulfonyl semicarbazide, N, N'-dimethyl-N, N'-dinitroso. Terephthalamide, N, N'-dinitrosopentamethylenetetramine, hydrazodicarbonamide, p-toluenesulfonylhydrazide, benzene-1,3-disulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, p-toluene One or more of these, such as sulfonyl semicarbazide, may be appropriately selected and used.

The foaming agent is 0.5 to 10 parts with respect to 100 parts of vinyl chloride resin,
Preferably 1.5 to 5 parts are used. If the amount is less than 0.5 parts, the amount of gas generated is small and the expansion ratio does not rise sufficiently. On the contrary, if it exceeds 10 times, it causes excessive foaming and cell destruction /
It is not preferable because communication is likely to occur.

If necessary, a foaming aid such as a kicker agent, a decomposition inhibitor, and a cell regulator may be added to the composition of the present invention. Also,
If desired, stabilizers, lubricants, fillers, ultraviolet absorbers, pigments, other thermoplastic resins, etc. may be blended and used.
The kind and addition amount of these may be appropriately selected according to the purpose.

The pelletized soft vinyl chloride resin composition for foaming used in the extrusion molding of the present invention may be subjected to foam molding by the same method as that for general soft vinyl chloride resin.

In the production of the pelletized compound, for example, the composition is mixed using a super mixer, a ribbon blender or the like, and the mixture is kneaded with a Banbury mixer, a kneader, a mixing roll, various extruders or the like at a temperature substantially lower than the temperature at which the foaming agent is decomposed. Granulate.

The soft vinyl chloride resin composition for foaming in the form of pellets used for extrusion molding of the present invention thus produced is a soft foam molded article by an extrusion molding method, particularly an extrusion foam molding method using a single-screw or twin-screw extruder. Can be

In addition, it can be molded by a method such as injection molding, calender molding, and press molding.

Hereinafter, the composition of the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

Examples 1 to 9 and Comparative Examples 1 to 4 Vinyl chloride resin 100 having an average degree of polymerization shown in Table 1.
In the parts, a methyl methacrylate copolymer having a specific viscosity and a glass transition temperature shown in Table 1 is shown in Table 1, dioctyl phthalate (hereinafter referred to as DOP) is shown in Table 1, Ba-Zn. 3 parts of a system stabilizer, 20 parts of calcium carbonate and a foaming agent were added in amounts shown in Table 1 and dried up using a super mixer. The obtained powdery compound was roll-kneaded at 140 ° C. for 10 minutes to prepare a masticated sheet having a thickness of about 3 mm, and the sheet was cut into about 3 mm squares to form a pellet, which was subjected to extrusion foam molding.

The extrusion foam molding experiment was carried out by mounting a round bar die having a die diameter of 4.5 mm on a 32 mm single screw extruder using a full flight screw with L / D = 24 and a compression ratio = 3.0.

The extrusion foaming conditions are as follows: Cylinder temperature from the hopper side is C ₁ = 155 ° C, C ₂ = 170 ° C, C ₃ = 170 ° C, adapter = 15.
The temperature was set at 0 ° C. and the die was 140 ° C., the screw rotation speed was 40 rpm, and after extrusion, air-cooling was performed to allow free foaming to obtain a foam-molded article.

The specific gravity, foaming ratio, surface smoothness and cell state of the obtained molded product were evaluated by the following methods. The results are shown in Table 1.

The roll kneadability was also evaluated by the following method. The results are shown in Table 1.

(Evaluation of roll kneading property) The powdery compound was put into a roll and evaluated by the ease of winding when winding and the tenacity of the sheet when taking out the sheet.

○: Wrapping is fast and the sheet has tenacity △: Wrapping is slow, but the sheet has tenacity ×: Wrapping is slow and the sheet is easily torn (molded product characteristics) The specific gravity of the molded product is JIS The measurement was carried out by the underwater displacement method of K 7112, and the specific gravity of the non-foamed molded product was divided by the specific gravity of the foamed molded product to obtain the expansion ratio.

The surface smoothness of the molded product was visually observed and evaluated according to the following criteria.

◯: Smooth Δ: Concavo-convex is conspicuous ×: Concavo-convex is remarkable. The cell state of the molded product is obtained by cutting the molded product with a cutter knife.
The cut surface was observed and evaluated according to the following criteria.

◯: Uniform independent cells Δ: Partially cell communication ×: Cell communication is significant and there are cavities.

From the results shown in Table 1, when a methyl methacrylate-based copolymer having a specific viscosity of 1.4 to 2.1 is used, roll kneading properties during the production of pelletized compounds are poor, and the appearance of foamed molded products and the state of foamed cells are also poor. However, when a methyl methacrylate-based copolymer having a specific viscosity of 2.9 or more is used, the kneading property at the time of producing the pelletized compound is improved, the cell state and appearance of the foam-molded product become very good, and the expansion ratio is also increased. It can be seen that it is higher than in the comparative example.

Even if the specific viscosity of the methyl methacrylate-based copolymer is as high as 5.1, if the glass transition temperature is as high as 110 ° C.,
It can be seen that the kneading property during the production of the pelletized compound is slightly lowered. If the kneading temperature is raised for this improvement, the foaming agent is decomposed and a pelletized compound having a stable expansion ratio cannot be obtained.

[Effects of the Invention] When an extrusion foam-molded article is produced using the resin composition of the present invention, a soft vinyl chloride-based resin excellent in surface smoothness, cell uniformity, and independence of the molded article at a foaming ratio of 1.3 times or more. A foamed molded product can be obtained.

Further, since the resin composition can easily produce a pelletized compound at a kneading temperature which is substantially lower than the temperature at which the foaming agent decomposes, the foaming agent is prevented from escaping and the amount of the foaming agent in the compound is kept constant. Easy to manage.

Claims (1)

[Claims] 1. A polymer containing 0.4 g of a copolymer containing methyl methacrylate as a main component per 100 parts by weight of a vinyl chloride resin.
1 to 30 parts by weight of methyl methacrylate-based copolymer having a specific viscosity of 2.5 ml or more of 00 ml of benzene solution measured at 30 ° C. and a glass transition temperature of 85 ° C. or less, a plasticizer 20 to 200 parts by weight and a decomposing type foaming agent. A soft vinyl chloride resin composition for foaming, which is pelletized and is used for extrusion molding by mixing 0.5 to 10 parts by weight.