JPS63139928A - Flexible vinyl chloride resin foam and its production - Google Patents

Abstract

PURPOSE:To obtain the title foam having uniform and dense closed cells and an excellent surface smoothness, by pelletizing a specified expandable flexible vinyl chloride resin composition and extrusion-foaming the pellets. CONSTITUTION:An expandable flexible vinyl chloride resin composition is obtained by mixing 100pts.wt. vinyl chloride resin of an average degree of polymerization of 600-4,500 with 5-150pts.wt. acrylonitrile/butadiene rubber of a solubility of 5-95wt% in methyl ethyl ketone at 25 deg.C, 1-60pts.wt. methyl methacrylate copolymer having a glass transition temperature <=85 deg.C and a specific viscosity >=2.5 (as measured in a solution of 0.4g of said copolymer in 100ml of benzene at 30 deg.C), 20-200pts.wt. plasticizer (e.g., dibutyl phthalate) and 0.5-10pts.wt. blowing agent (e.g., barium azodicarboxylate). This composition is kneaded at 100-190 deg.C to form pellets, and the pellets are extrusion- foamed at 100-200 deg.C to obtain a flexible vinyl chloride resin foam of an expansion ratio of 1.3-2.5.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a foam molded product obtained by an extrusion foam molding method, etc., which has a foaming ratio of 1.3 to 2.5 times, and has dense and uniform closed foam. The present invention relates to a soft vinyl chloride resin foam molded product that allows cells to grow and has extremely good surface smoothness, and a method for producing the same.

[Conventional technology]

Methods for producing vinyl chloride resin foams by extrusion foam molding include methods that use an evaporative foaming agent and methods that use a decomposable foaming agent.

The method of using a decomposable foaming agent has the advantage that it can be used by simply modifying a conventional extruder, and the process is simple, so it is often used in the production of low to medium foaming molded products. It is used.

However, when a plasticizer is added to vinyl chloride resin,
Even if a product is manufactured by extrusion foam molding by adding a decomposable blowing agent to a so-called soft vinyl chloride resin composition, soft vinyl chloride has dense and uniform closed cells and has extremely good surface smoothness. Resin foam molded products can only be obtained with a foaming ratio of less than about 1.2 times.

Furthermore, if normal kneading temperatures are used to produce pelletized compounds for extrusion foam molding, the blowing agent decomposes, making it impossible to strictly control the amount of blowing agent in the compound. It is not possible to create a compound with good reproducibility, or even a foam molded product with a stable expansion ratio and shape. On the other hand, if the mixing wire temperature is lowered to suppress the decomposition of the blowing agent, kneading becomes insufficient. A problem arises in that it becomes difficult to manufacture the compound, and as a result, it becomes impossible to strictly control the expansion ratio, shape, etc. of the foam molded product.

Furthermore, as shown in JP-A No. 61-68732, a decomposable blowing agent is added to a soft vinyl chloride resin composition prepared by adding acrylonitrile-butadiene rubber for the purpose of reducing permanent deformation. When products are manufactured by extrusion foam molding, the above problems become more pronounced.

A common method for solving such problems during extrusion foam molding is the addition of a processability improver, and it is well known that this method is effective to some extent. For example, as shown in JP-A-51-5371 and JP-A-58-52827, the so-called two-stage foaming method, in which a sheet is first formed and then foamed in a foaming furnace, has no effect. It recognized.

However, in the so-called extrusion foam molding method in which foaming is performed at the exit of a die during extrusion molding, a processability improver that is a commonly used copolymer mainly composed of methyl methacrylate and has a specific viscosity of 1 to 2 is added. However, the soft vinyl chloride resin foam molded product, which has dense and uniform closed foam cells, has a foaming ratio of 1.3 times or more, and has extremely good surface smoothness, cannot be mixed, making it difficult to manufacture compounds. The problems of time remain unresolved.

[Problem that the invention seeks to solve]

The present invention has the following advantages: (1) When producing a pellet-like compound for extrusion foam molding, it is difficult to knead the soft extrusion foam molded product of vinyl chloride resin at a temperature that suppresses the decomposition of the blowing agent. Therefore, it is not possible to adequately control the amount of blowing agent in the pelletized compound, and as a result, it is not possible to produce foam molded products with stable expansion ratio, shape, etc. and good reproducibility. This was done in order to solve the problem that foam molded products having a foaming ratio of 1.3 times or more and extremely good surface smoothness are not being replaced.

[Means for solving problems]

The present invention uses acrylonitrile-butadiene rubber (hereinafter referred to as NBR) which is dissolved in methyl ethyl ketone (hereinafter referred to as MEK) in an amount of 5 to 95% (by weight, hereinafter the same) based on 100 parts (by weight, the same hereinafter) of a vinyl chloride resin. )5
Methyl methacrylate-based copolymer 1 having a specific viscosity determined by Δ-J at 30°C of 2.5 or more in 100 ml of a benzene solution containing ~150 parts and 0.4 g of a copolymer mainly composed of methyl methacrylate A foaming ratio of 1.2 to 2 consisting of a soft vinyl chloride resin composition containing 60 parts and 20 to 200 parts of a plasticizer.
．． 5 to 95% of MEK for 5 times soft vinyl chloride resin foam molded product and 100 parts of vinyl chloride resin
Methyl methacrylate-based copolymer 1 having a specific viscosity of 2.5 or more when measured at 30°C in 100 ml of a benzene solution containing 5 to 150 parts of dissolved NBR and 0.4 g of a copolymer mainly composed of methyl methacrylate. ~60 parts, plasticizer 20-2
A soft vinyl chloride resin composition for foaming containing 0.00 parts and 0.5 to IO parts of a blowing agent is kneaded at 100 to 190°C to form pellets, and then the pellets are extruded and foam-molded at a molding temperature of 100 to 200°C. Foaming ratio: 1.3 to 2.5
This invention relates to a method for producing a soft vinyl chloride resin foam molded product.

[Example] The vinyl chloride 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 copolymer resin containing 85% or more of vinyl chloride, or a vinyl chloride copolymer resin containing 85% or more of vinyl chloride. % or more, and includes partially crosslinked vinyl chloride resins containing 5 to 90% gel content that is insoluble in tetrahydrofuran, and any conventionally known vinyl chloride resins may be used as long as they meet the above regulations. It can be used even if there is.

Specific examples of vinyl chloride copolymer resins containing 85% or more of vinyl chloride include copolymer resins with vinyl esters such as vinyl acetate and vinyl stearate, and copolymer resins with olefins such as ethylene and propylene. ,
Butyl (meth)acrylate, (meth)acrylic acid-2-
Copolymer resins with (meth)acrylates such as ethylhexyl, copolymer resins with maleate esters such as butyl maleate and octyl maleate, and copolymer resins with fumarate esters such as butyl fumarate and octyl fumarate. Examples include copolymer resins and copolymer resins with these acids, but are not limited thereto.

Specific examples of the partially crosslinked vinyl chloride resin include diallyl phthalate, diallyl maleate, polyethylene glycol di(meth)acrylate, Examples include, but are not limited to, resins obtained by copolymerization using polyfunctional compounds such as 2-polybutadienes.

Furthermore, these vinyl chloride resins may be used alone or in combination of two or more, and when used in combination, the mixing ratio may be freely selected depending on the purpose.

The average degree of polymerization of the vinyl chloride resin is preferably from 600 to 4,500, more preferably from 1,000 to 3,200. If the average degree of polymerization is less than 600, it is likely to be difficult to mix a plasticizer and dry up, and permanent deformation tends to be large, and the average degree of polymerization is less than 450.
If it exceeds 0, it becomes difficult to sufficiently knead, which is not preferable.

NBR used in the present invention is 5 to 95% of MEK at 25°C.
%, preferably 10 to 60%, and the compression set of a foam molded product using this partially crosslinked NBR can be reduced, and the restoring force after stress can be improved. First, since the temperature dependence of the melt viscosity of the compound during extrusion foam molding can be reduced, the molding temperature range during extrusion foam molding can be widened.

If the NBR dissolves in MEK by more than 95%, the effect of reducing the compression set and the effect of reducing the temperature dependence of melt viscosity during extrusion foam molding will not be sufficient, which is preferable. do not have. MEK 1 on the contrary
．． : If less than 5% is dissolved, extrusion moldability will deteriorate, which is not preferable.

In the present invention, dissolving in MEK means 25°C.
This means extracting with MEK at a temperature of 48 hours and passing through a 100 mesh filter.

The acrylonitrile content of the NBR is preferably 25 to 50% in terms of compatibility with the vinyl chloride resin,
Particularly preferably, it is 30 to 45%.

The NBR is 5 to 100 parts of vinyl chloride resin.
150 parts are used, preferably 10-120 parts. If the amount used is less than 5 parts, the effect of reducing compression set and the effect of reducing the temperature dependence of melt viscosity during extrusion foam molding will not be sufficient, which is not preferable. On the other hand, if it exceeds 150 parts, crosstalk during pellet production, moldability during extrusion foam molding, etc. will decrease, and the properties of vinyl chloride resins such as heat aging resistance, ozone resistance, and weather resistance will be lost. This is not desirable as it may cause damage.

The methyl methacrylate copolymer used in the present invention is a copolymer containing methyl methacrylate as a main component, that is, 50 to 95%, and contains 0.4 g of the copolymer.
The specific viscosity of 0ml of benzene solution measured at 30°C is 2.
It has a high molecular weight of 5 or more, preferably 2.5 to 6.0, and preferably has a glass transition temperature of 85°C or less. If the specific viscosity is less than 2.5, the cell uniformity, independence, surface smoothness, etc. of the resulting foamed product will not be sufficiently improved, the expansion ratio will not be improved, and the production of pellet-like compounds will not be possible. The kneading properties at temperatures below the temperature at which the blowing agent substantially decomposes are also not sufficiently improved. Note that in order to further improve cross-talk during the production of pellet-like compounds, it is preferable to use a material with a glass transition temperature of 85° C. or lower.

Components other than methyl methacrylate in the methyl methacrylate copolymer include, for example, ethyl acrylate, propyl acrylate, butyl acrylate, and -2 acrylate.
- Acrylic esters such as ethylhexyl, methacrylic esters (excluding methyl methacrylate) such as ethyl methacrylate, propyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. These components may be simply copolymerized or graft polymerized, and furthermore, a small amount of the above-mentioned crosslinking agent may be copolymerized during these polymerizations.

The methyl methacrylate copolymer is used in an amount of 1 to 60 parts, preferably 5 to 40 parts, per 100 parts of the vinyl chloride resin. If the amount used is less than 1 part, the expansion ratio will not be sufficiently improved, and if it exceeds 60 parts, the foamed molded product will become hard, have poor flexibility, and increase cost, which is undesirable. The methyl methacrylate copolymers may be used alone or in combination of two or more.

The plasticizer used in the present invention is a component added to give the molded product flexibility, rubber feel, etc., and is 20 to 200 parts, preferably 3 parts to 100 parts of the vinyl chloride resin.
0 to 160 parts are used. If the amount used exceeds 200 parts, the heat deformation resistance and cell independence of the molded product will deteriorate, which is undesirable. If the amount is less than 20 parts, the molded product will have flexibility and
It is not preferable because it cannot provide a sufficient rubber feel.

Specific examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, diisononyl phthalate, diisodecyl phthalate,
Alkyl esters of aromatic polybasic acids such as trioctyl trimellitate and triisooctyl trimellitate; aliphatic polybasic acids such as dibutyl adipate, dioctyl adipate, diisononyl adipate, dibutyl azelate, dioctyl azelate, and diisononyl azelate; alkyl esters, phosphoric acid alkyl esters such as tricresyl phosphate, and even polyester plasticizers,
Commonly used plasticizers include epoxy plasticizers and chlorinated paraffin. These may be used alone or in combination of two or more.

Foaming agents are used in the production of the foam molded products of the present invention, and specific examples thereof include barium azodicarboxylate, hydrazodicarbonamide, azodicarbonamide, 4.4°-oxybisbenzenesulfonyl semicarbazide, etc. , N,N'-dimethyl-N,N'-dinitrosoterephthalamide, N,N'-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, benzene-1,3-disulfonylhydrazide, diphenylsulfone-3, Examples include 3°-disulfonyl hydrazide and p-toluenesulfonyl semicarbazide, and one or more of these may be appropriately selected and used.

The blowing agent is used in an amount of 0.5 to 100 parts of vinyl chloride resin.
10 parts are used, preferably 1.5 to 5 parts.

If the amount used is less than 0.5 parts, the foaming ratio will not increase sufficiently because the amount of gas generated is small; on the other hand, if it exceeds 10 parts,
This is undesirable because excessive foaming occurs, causing cell destruction and Q-connection, which tends to reduce the uniformity and independence of the cells.

When producing the extruded foam molded product of the present invention, stabilizers, lubricants, fillers, ultraviolet absorbers, pigments, rubbers, and thermoplastic resins such as polyurethane resins and polyester resins may be used as necessary. Foaming aids such as foaming agents, decomposition inhibitors, cell regulators, etc. may also be used, and the type and amount thereof may be appropriately selected depending on the purpose.

In order to manufacture the soft vinyl chloride resin foam molded product of the present invention, for example, the essential components are blended and formed into pellets using the process of manufacturing general vinyl chloride soft resin compositions, and then the pellets are extruded and foamed. Obtained by molding.

In other words, when blending, use a Henschel mixer,
Using a conventionally known blender such as a super mixer or a ribbon blender, add all or part of the essential ingredients such as vinyl chloride resin other than the plasticizer, then add the plasticizer all at once, intermittently or continuously. The temperature is raised to 60 to 150°C to dry up the plasticizer, and a powdery compound of soft vinyl chloride resin is produced.

At this time, the essential components other than the vinyl chloride resin may be added at the same time as the vinyl chloride resin, after drying up, or during drying up.

Next, the mixture is supplied to a pressure kneader, co-kneader, mixing roll, various extruders, etc., and kneaded at a temperature substantially below the decomposition temperature of the blowing agent to produce a pellet-like compound of a soft vinyl chloride resin composition. do it. The temperature of this crosstalk varies depending on the composition of the compound, but
Usually about 100-190℃, preferably 120-1(
It is about 0°C.

Subsequently, a flexible foam molded product is produced from the pellet-shaped compound by extrusion molding using various single-screw or twin-screw extruders equipped with dies having various shapes depending on the purpose of the molded product.

During extrusion molding, it may be co-extruded with metal products, soft PvC or its products, hard PVC or its products, etc.

The molding temperature is preferably in the range of 100 to 200°C, and it is particularly desirable to set the die temperature lower than the cylinder tip temperature and to perform molding while maintaining this temperature difference at 5°C or more.

There is no particular limitation on the screw shape of the extruder, and conventionally known screws such as the Dalmage type and full flight type may be used. The L/D of the screw is preferably 15 to 40, particularly preferably 15 to 30. Further, the compression ratio of the screw is preferably 1.0 to 5.0, particularly 1
．． It is preferably between 5 and 3.5.

The foam molded product obtained in this way has a foaming ratio of 1.3 to
2.5 times the size, it has dense and uniform closed foam cells, and has excellent sealing properties, cushioning properties, sound insulation properties, and heat insulation properties, and the surface smoothness of the molded product is also extremely good, and the appearance is It can also be used in product fields that require good quality.

Such foam molded products are used, for example, in automotive parts such as moldings, glass channels, weather strips, trims, various cushion members, and various seal members, anti-slip products, furniture edging, and seals. Vinyl chloride-based soft resin, polyurethane, EPDM as sheet-like, tube-like, or various shaped articles for architectural parts such as sound insulation, vibration isolation, heat insulation, protection, sealing, cushioning, etc. It is suitable for use in fields where extrusion molded products such as

EXAMPLES Below, the soft vinyl chloride resin foam molded product of the present invention and its manufacturing method will be explained in more detail based on Examples, but the present invention is not limited thereto.

Examples 1 to 10 and Comparative Examples 1 to 3 Vinyl chloride resin 10 having an average degree of polymerization of a shown in Table 1
0 parts, partially crosslinked NBR (acrylonitrile 33% by weight) having the solubility in MIEK shown in Table 1 was added to the first part.
The amount shown in Table 1, the amount of methyl methacrylate copolymer having the specific viscosity and glass transition temperature shown in Table 1 shown in Table 1, the amount of dioctyl phthalate (hereinafter referred to as DOP) shown in Table 1, Ba -3 parts of Zn-based stabilizer, 20 parts of calcium carbonate, and a blowing agent were added in the amounts shown in Table 1, and the mixture was dried up using a super mixer.

The obtained powder compound was roll-kneaded at 140° C. for 10 minutes to produce a masticated sheet with a thickness of about 3 am. No decomposition of the blowing agent was observed at 140°C. This sheet was cut into approximately 31 square pieces, formed into pellets, and subjected to extrusion foam molding.

Extrusion foam molding is carried out using a 5-hour single-screw extruder using a full-flight screw with L/D-22 and a compression ratio of -3.0. A die (1) for a sealing member) was installed, and an automobile sealing member (2) was extruded.

The extrusion foam molding conditions are: cylinder temperature from the hopper side: CI -155℃, C2-170℃, C3-170℃
The extrusion was carried out at a temperature of 150° C. for the adapter and 140° C. for the die, and a screw rotation speed of 40 rpm. After extrusion, the extrusion was air-cooled to allow free foaming to obtain a foamed molded product.

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

(Evaluation of Roll Kneadability) A powdery compound was placed on a roll and evaluated based on the ease with which it was wound and the tenacity of the sheet when it was taken out.

○: Wrapping is fast, and the sheet is tenacious. Δ: Wrapping is slow, but the sheet is tenacious. ×: Wrapping is slow, and the sheet is easy to tear (molded product characteristics). The foaming ratio was determined by dividing the specific gravity of the non-foamed molded product by the specific gravity of the foamed molded product.

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

O: Smooth Δ: Noticeable unevenness ×: The cell condition of a molded product with significant unevenness can be determined by cutting the molded product with a cutter knife.
The cut surface was visually observed and evaluated according to the following criteria.

O: Uniform independent cells △: Partial cell communication ×: Cell communication is significant and the compression set of a molded product with cavities is due to the spacer (3) shown in Figure 2. Using the device (4), JIS K630
11 was determined in the same manner as the measurement of compression set in 1. The compression ratio was 53%, and the compression conditions were 70'C for 22 hours.

[Margin below]

From the results in Table 1, it is clear that when a methyl methacrylate copolymer with a specific viscosity of 1.4 to 2.1 is used, the roll kneading properties at temperatures below the decomposition temperature of the blowing agent during the production of pellet-like powder pounds are also poor. Although the appearance of the foam molded product and the condition of the foam cells are poor, the specific viscosity of the methyl methacrylate copolymer is 2.9.
It can be seen that when the above materials are used, the roll kneading properties during the production of pellet-shaped compounds are improved, the cell condition and appearance of the foamed molded products are very good, and the expansion ratio is also higher than that of the comparative example.

〔Effect of the invention〕

The vinyl chloride resin soft extrusion foam molded product of the present invention has 1.
While maintaining a foaming ratio of 3 times or more, the surface of the molded product is smooth, and the cell state is uniform and has excellent independence. Therefore, it is possible to use vinyl chloride resin flexible foam molded products that have excellent sound insulation, vibration isolation, heat insulation, protection, sealing, and cushioning properties, whereas conventionally only EPDM and polyurethane rubber foams could be used. It can also be used satisfactorily in other fields.

Furthermore, the foamed molded product of the present invention can be produced by the method of the present invention.
It has good reproducibility in terms of expansion ratio, shape, etc., and can be easily manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the cross-sectional shape of the tip of a die for a profile extrusion molded product (sealing member for automobiles) used for extrusion foam molding of a soft vinyl chloride resin foam molded product, and FIG. FIG. 3 is an explanatory diagram showing a method of measuring compression set using a test piece manufactured using the mold shown in FIG.

Claims (1)

[Scope of Claims] 1. 100 parts by weight of vinyl chloride resin, 5 to 150 parts by weight of acrylonitrile-butadiene rubber dissolved in 5 to 95% by weight in methyl ethyl ketone, and 0.0 parts by weight of a copolymer mainly composed of methyl methacrylate. A soft vinyl chloride resin composition containing 1 to 60 parts by weight of a methyl methacrylate copolymer having a specific viscosity of 2.5 or more when measured at 30°C in 100 ml of a benzene solution containing 4 g, and 20 to 200 parts by weight of a plasticizer. A soft vinyl chloride resin foam molded product with a foaming ratio of 1.3 to 2.5 times. 2. 100 ml of benzene containing 5 to 150 parts by weight of acrylonitrile-butadiene rubber dissolved in 5 to 95% by weight in methyl ethyl ketone and 0.4 g of a copolymer mainly composed of methyl methacrylate, per 100 parts by weight of vinyl chloride resin. A foaming soft material containing 1 to 60 parts by weight of a methyl methacrylate copolymer having a specific viscosity of 2.5 or more when measured at 30° C., 20 to 200 parts by weight of a plasticizer, and 0.5 to 10 parts by weight of a blowing agent. The vinyl chloride resin composition is 100 to 1
Knead at a temperature of 90°C to pelletize the pellets.
A method for producing a soft vinyl chloride resin foam molded product with an expansion ratio of 1.3 to 2.5 times by extrusion foam molding at a molding temperature of 00 to 200°C.