JPH07107106B2 - Flexible vinyl chloride foamed molded product with small permanent set - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a foaming ratio of a molded product.
The present invention relates to a foam-molded article made of a specific soft vinyl chloride resin composition having a ratio of 1.2 to 2.5 times and a small permanent set.

[0002]

2. Description of the Related Art Conventionally, a so-called soft vinyl chloride resin composition obtained by adding a plasticizer to a vinyl chloride resin for the purpose of reducing the weight of a soft vinyl chloride product and improving its sound insulation, heat insulation and sealing properties. Although a foamed molded product from is manufactured and used, it is possible to obtain a soft vinyl chloride foamed molded product that has dense and uniform independent foam cells, expansion ratio of 1.2 times or more, and small permanent set. Not used, and used only to a limited extent.

As a method for producing a vinyl chloride foamed molded article, there are an extrusion foaming molding method, an injection molding method, a calender molding method, and the like, and a method of manufacturing using an evaporative foaming agent and a decomposition type foaming agent. There is a manufacturing method using.

The production method using a decomposition type foaming agent by the extrusion foam molding method has the advantages that it can be diverted by slightly modifying the conventionally used extruder and that the process is simple. It is widely used in the production of low-foam to medium-foam molded products. In particular, in the field of extrusion foam molded products, in addition to permanent set, expansion ratio, and uniformity of foam cells, a molded product having a stable extrusion shape, a smooth surface, and a good appearance is demanded. , Such foam-molded products have not been obtained.

The addition of a processability improver is a generally adopted method for solving the problems such as the expansion ratio of foamed molded products, the uniformity of foam cells, and the moldability in extrusion molding. It is well known that the method is effective to some extent. For example, as disclosed in JP-A-51-5371 and JP-A-58-52327, in the so-called two-stage foaming method in which a sheet is first molded and then foamed in a foaming furnace, Its effect has been recognized in terms of improving the expansion ratio of a molded product, the uniformity of foam cells, and the like. However, the effect is not recognized in general extrusion foam molding.

That is, in a general extrusion foam molding method, even if a commonly used copolymer containing methyl methacrylate as a main component and having a specific viscosity of 1 to 2 is added, it is dense and uniform. It has an independent foam cell and a foaming ratio of 1.2.
It is not possible to obtain a foamed molded product having a surface smoothness of more than double. Further, even in the injection molding method or the like, the addition of the processability improver having the specific viscosity of 1 to 2 causes the expansion ratio to be increased.
No foamed molded product with a density of 1.2 or more and dense and uniform closed cells has been obtained.

On the other hand, as disclosed in JP-A-61-66732, a decomposable foaming agent is added to a soft vinyl chloride resin composition containing a partially crosslinked acrylonitrile-butadiene rubber for the purpose of reducing permanent set. When extrusion foaming is carried out by adding, the permanent strain is reduced, but the problem that the expansion ratio is difficult to increase and uniform foam cells cannot be obtained becomes more prominent. Therefore, it is extremely difficult to obtain a foamed molded product having a compression set of 50% or less and a dense and uniform foam cell with a foaming ratio of 1.2 or more, only by adding the partially crosslinked acrylonitrile-butadiene rubber. .

[0008]

DISCLOSURE OF THE INVENTION The present invention, when trying to obtain a soft vinyl chloride resin composition foam-molded article by various foam-molding methods, according to the conventional technique, the foamed state of the foam-molded article is dense and uniform. The state of independent foam cells and the expansion ratio
This is done to solve the problem that a foamed molded product having a ratio of 1.2 times or more and a reduced permanent set cannot be obtained, and that it is used only in a limited range.

[0009]

According to the present invention, 100 parts (parts by weight, hereinafter the same) of vinyl chloride resin dissolves in methyl ethyl ketone (hereinafter, referred to as MEK) by 5 to 90% (% by weight, the same below). 100 including acrylonitrile-butadiene rubber (hereinafter referred to as NBR) 5 to 150 parts and a copolymer containing methyl methacrylate as a main component 0.4 g
2.5 ml specific viscosity of benzene solution measured at 30 ° C is 2.5
Permanent set 15-40 at a foaming ratio of 1.2-2.5, which is made of a soft vinyl chloride resin composition containing 1 to 60 parts of the above methyl methacrylate copolymer and 20 to 200 parts of a plasticizer.
% Soft vinyl chloride foam molded article.

[0010]

[Functions and Examples] The vinyl chloride resin used in the present invention is a vinyl chloride resin obtained by homopolymerizing a vinyl chloride monomer or a vinyl chloride copolymer containing 85% or more vinyl chloride. It may be a partially cross-linked vinyl chloride resin containing a component, and any conventionally known vinyl chloride resin may be used as long as it complies with the above regulations.

Examples of the copolymer component other than vinyl chloride in the vinyl chloride copolymer containing 85% or more vinyl chloride include vinyl esters such as vinyl acetate and vinyl stearate, olefins such as ethylene and propylene, and the like.
Butyl (meth) acrylate, (meth) acrylic acid-2-ethylhexyl and other (meth) acrylic acid esters, butyl maleate, octyl maleate and other maleic esters, butyl fumarate, fumaric octyl and other fumarates Examples thereof include acid esters and these acids, but are not limited thereto. Two or more of these components other than vinyl chloride may be used in combination.

As the partially crosslinked vinyl chloride resin containing a gel component, for example, polyfunctional compounds such as diallyl phthalate, diallyl maleate, polyethylene glycol di (meth) acrylate and 1,2-polybutadiene as a crosslinking agent are used. Examples thereof include resins obtained by copolymerization using, but are not limited to these.

Two or more kinds of these vinyl chloride resins may be used in combination, and the ratio of the combination may be freely selected according to the purpose.

The vinyl chloride resin has an average degree of polymerization of 600 to 45.
It is preferably 00, particularly preferably 1000 to 3200. If the average degree of polymerization is less than 600, it is difficult to dry up the plasticizer when it is mixed, and the permanent set of the molded product becomes large, which is not preferable. On the other hand, when the average degree of polymerization exceeds 4,500, it tends to be difficult to sufficiently gelate.

The NBR used in the present invention is 5 in MEK.
It is a partially crosslinked NBR that dissolves at 90% (25 ° C), preferably at 10-60%. Use of partially crosslinked NBR that dissolves in MEK at 5 to 90% (25 ° C) not only reduces the compression set of foamed molded products and improves the restoring force after stress is applied, but also foamed molding. At this time, the temperature dependence of the melt viscosity can be reduced, so that the temperature range during foam molding can be widened.

If the NBR is dissolved in MEK in an amount of more than 90%, the effect of reducing the compression set and the effect of reducing the temperature dependency during foam molding are insufficient, which is not preferable. On the other hand, if less than 5% is dissolved in MEK, the moldability is lowered, which is not preferable.

Dissolving in MEK means extracting with MEK at a temperature of 25 ° C. for 48 hours and passing through a 100-mesh filter.

The NBR used in the present invention is used in an amount of 5 to 150 parts, preferably 10 to 120 parts, per 100 parts of the vinyl chloride resin. If the amount used is less than 5 parts, the effect of reducing the compression set is not sufficiently obtained, which is not preferable. vice versa,
If it exceeds 150 parts, the kneading property at the time of pellet production, the moldability at the time of foam molding become poor, and further the heat aging resistance, ozone resistance, weather resistance and the like become poor, which is not preferable.

The methyl methacrylate-based copolymer used in the present invention contains methyl methacrylate as a main component, that is, contains 50 to 95% of methyl methacrylate, and an acrylic acid ester and / or a methacrylic acid ester (methyl methacrylate). And (or) a small amount of a cross-linking agent or a graft copolymer.

The molecular weight of the methyl methacrylate copolymer is 30 times that of 100 ml of a benzene solution containing 0.4 g of the copolymer.
Specific viscosity measured at ℃ is 2.5 or more, preferably 2.5 to 6.0
And a glass transition temperature of 85 ° C. or lower. The specific viscosity is
When it is less than 2.5, the uniformity and independence of the cells of the foamed molded product, the surface smoothness of the extrusion molded product, and the like are not improved, and the expansion ratio is not increased, which is not preferable. Further, in order to improve the kneading property at the time of producing the pellet compound, the glass transition temperature is preferably 85 ° C. or lower.

The methyl methacrylate copolymer used in the present invention is used in an amount of 1 to 60 parts per 100 parts of vinyl chloride resin. If the amount used is less than 1 part, a sufficient effect of improving the expansion ratio does not occur. On the contrary, if it exceeds 60 parts, the molded product becomes hard and inflexible, and the cost increases, which is not preferable. Two or more methyl methacrylate copolymers may be used in combination.

The plasticizer used in the present invention is added in order to give the molded product flexibility and rubber feel, and specific examples thereof include dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, and the like.
Alkyl esters of aromatic polybasic acids such as diisononyl phthalate, diundecyl phthalate, trioctyl trimellitate, triisooctyl trimellitate, dibutyl adipate, dioctyl adipate, diisononyl adipate, dibutyl azelate, dioctyl azelate, diisononyl azelate Alkyl esters of aliphatic polybasic acids such as, phosphoric acid alkyl esters such as tricresyl phosphate, and further polyester plasticizers,
Examples of the commonly used plasticizers include epoxy plasticizers and chlorinated paraffins. These may be used alone or in combination of two or more.

The plasticizer is based on 100 parts of vinyl chloride resin
20 to 200 parts, preferably 30 to 160 parts are used. If the amount used exceeds 200 parts, the heat distortion resistance of the molded product and the independence of the cells are deteriorated, which is not preferable. , Not preferable.

Examples of the foaming agent used in the present invention include barium azodicarboxylate, hydrazodicarbonamide, azodicarbonamide, 4,4'-oxybisbenzenesulfonyl semicarbazide, N, N'-dimethyl-N,
N'-dinitrosoterephthalamide, N, N'-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, benzene-1,3-disulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, p-toluene Examples thereof include sulfonyl semicarbazide. These may be used alone or in combination of two or more kinds as appropriate.

The blowing agent is based on 100 parts of vinyl chloride resin
0.5-10 parts, preferably 1.5-5 parts are used. If the amount used is less than 0.5 part, the amount of gas generated is small, and the expansion ratio does not increase, which is not preferable. On the other hand, if the amount used exceeds 10 parts, it is not preferable because over-foaming results in cell breakage and communication, and the uniformity and independence of the cells deteriorate.

When producing the foamed molded article of the present invention, if necessary, stabilizers, lubricants, fillers, ultraviolet absorbers, pigments, rubbers (excluding partially crosslinked NBR), polyurethane resins, polyester resins, etc. Resin, ethylene-vinyl acetate copolymer, thermoplastic resin such as chlorinated polyethylene may be blended and used, and further, a kicking agent, a decomposition inhibitor, a foaming aid such as a cell regulator may be used. Well, the kind and the addition amount may be appropriately selected according to the purpose.

In producing the soft vinyl chloride foamed molded article of the present invention, the components are blended and pelletized by using, for example, a step of producing a general soft vinyl chloride resin composition, and then the pellets are foamed. It may be molded, and then the molded product may be heat-treated.

That is, at the time of blending, a conventionally known blender such as a Henschel mixer, a super mixer or a ribbon blender is used, and after adding components such as a vinyl chloride resin, the plasticizer is added all at once, intermittently or continuously. The temperature is raised to 80-150 ° C to dry up the plasticizer to produce a soft vinyl chloride resin powder compound. At this time, the components other than the vinyl chloride resin may be added after the dry-up, or may be added during the dry-up.

Then, the mixture is fed to a pressure kneader, a cokneader, a mixing roll, various extruders, etc.
Kneading is performed at a temperature of 00 to 200 ° C to produce a pellet compound of a soft vinyl chloride resin composition.

As the foam molding method, a molding method which has been generally used in the past, such as an extrusion molding method, an injection molding method or a calender molding method can be used.

In the case of molding by the extrusion foam molding method, extrusion molding using various single-screw or twin-screw extruders equipped with dies having various shapes according to the purpose of the molded product of the pellet compound. A soft vinyl chloride foamed molded product is manufactured by the molding method. During extrusion foam molding, it may be coextruded with metal, soft PVC, hard PVC, or the like.

The molding temperature in the extrusion foam molding method is usually
It is carried out in the range of 100 to 200 ° C., preferably the temperature of the die is set lower than the temperature at the tip of the cylinder, and it is preferable to carry out molding while maintaining the temperature difference at 5 ° C. or more.

The screw shape is not particularly limited, and a conventionally known screw such as a dullage type or full flight type screw can be used. The L / D of the screw is preferably from 15 to 40, more preferably from 15 to 30. The screw compression ratio is preferably 1.0 to 5.0, and particularly 1.5 to 5.0.
3.5 is preferable.

In this way, at a foaming ratio of 1.2 to 2.5 obtained by extrusion molding, injection molding, calender molding, etc.,
In addition, 40 foam molded products with dense and uniform independent foam cells
Heat treatment at 120 ° C for 20 minutes or more significantly improves the permanent set. Up to now, there is no known method for significantly reducing the permanent set by heat treatment.

The heat treatment of the foamed molded product is carried out at 40 to 120 ° C. for 20 hours.
As long as it is heat-treated for more than 1 minute, it may be treated continuously,
It may be processed intermittently, and there is no particular limitation on the device, and it may be left standing in a heating furnace such as a hot air dryer,
The treatment may be carried out while slowly moving in the heating furnace, but it is preferable to carry out the treatment at 60 to 100 ° C. for 1 to 24 hours. If the treatment temperature is lower than 40 ° C, there is almost no effect of reducing the permanent set, which is not preferable, and if it exceeds 120 ° C, there is almost no effect of reducing the permanent set, and the molded product is deformed or the appearance is deteriorated. There is a possibility of doing so, which is not preferable. Further, if the treatment time is less than 20 minutes, there is almost no effect of reducing the permanent set, which is not preferable.

The foamed molded product thus obtained has a foaming ratio of 1.2 to 2.5 and a compression set of 15 to 40 % .
It has dense and uniform independent foam cells, and has elasticity for rubber,
It has excellent sealing properties, cushioning properties, sound insulation properties, and heat insulation properties. Further, a molded product obtained by extrusion foam molding and obtained by heat treatment has particularly excellent surface smoothness and is particularly suitable for a product field requiring a good appearance.

The compression set referred to in the present invention is measured according to JIS K 63 using the device 4 having the spacer 3 shown in FIG.
The value was measured by the same method as the method for measuring the compression set of 01 at a compression rate of 53% and a compression condition of 70 ° C for 22 hours.

The measured value of the compression set may vary considerably depending on the shape of the molded product, and the value of 15 to 40% may be, for example, 10 to 45% depending on the shape.

The foamed molded product of the soft vinyl chloride resin composition having a small permanent strain thus obtained is, for example, moldings, glass run channels, weather strips, trims, various cushion members, various sealing members, etc. Automotive parts, non-slip, furniture edging,
Soft vinyl chloride resin as a sheet-shaped, tube-shaped or various shaped article for the purpose of building materials such as seals, sound insulation, vibration isolation, heat insulation, protection, sealing, cushioning, etc. It can be preferably used in fields where molded articles such as polyurethane and EPDM are used.

The foamed molded product of the soft vinyl chloride resin composition having a reduced permanent set according to the present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 10 and Comparative Examples 1 to 3 To 100 parts of vinyl chloride resin having an average degree of polymerization shown in Table 1, partially crosslinked NBR having solubility for MEK shown in Table 1 (33% of acrylonitrile component) was added. The amount shown in Table 1,
The amount of the methyl methacrylate copolymer having the specific viscosity and the 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,
A Zn-based stabilizer (3 parts), calcium carbonate (20 parts) and a foaming agent were added in the amounts shown in Table 1 and dried up using a super mixer. The obtained powder compound at 140 ℃
After kneading for 10 minutes to prepare a masticated sheet having a thickness of about 3 mm, the masticated sheet was cut into about 3 mm square and pelletized, and extrusion foam molding was performed.

In extrusion foam molding, L / D = 22, compression ratio = 3.0
Cylinder temperature from the hopper side to C ₁ = 155 ° C, C
₂ = 170 ° C, C ₃ = 170 ° C, adapter = 150 ° C, die = 140 ° C, screw rotation speed 40 rpm,
An automobile seal member 2 was extruded using a profile extrusion mold 1 having the shape shown in FIG. The molded product was subjected to free foaming by air cooling and then subjected to a heat treatment under the conditions shown in Table 1, subjected to specific gravity measurement and appearance evaluation by the following methods, and then the molded product was subjected to an apparatus 4 having a spacer 3 shown in FIG. Then, the permanent set was measured by the same method as the method for measuring the compression set of JIS K6301 (in the apparatus 4 shown in FIG. 2 preheated at 70 ° C., the thickness (between the upper and lower compression plates in FIG. 2) was measured. The molded product 2 which has been measured is pressed to the spacer 3 with the upper compression plate so that the compression rate becomes 53%, and the compression plate is fixed with bolts.After setting the molded product, immediately put it in a constant temperature bath at 70 ° C. After 22 hours, the molded product 2 is taken out of the apparatus and allowed to cool at room temperature, and after 30 minutes, the thickness is measured, and the compression set is determined by the following formula.

[0043]

[Equation 1]

(Where t ₀ is the original thickness of the molded product 2 (m
m), t ₁ is the thickness (mm) after the molded product 2 taken out from the apparatus 4 is allowed to cool for 30 minutes, and t ₂ is the length of the spacer 3 (m
m))). The results are shown in Table 1.

(Specific gravity and expansion ratio of molded product) JIS
The specific gravity was measured by the underwater substitution 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.

(Appearance of molded product) Visual observation was carried out to evaluate surface smoothness and cell condition based on the following criteria. For the cell state, the molded product was cut with a cutter knife and the cut surface was observed.

Surface smoothness ○: Smoothness Δ: Conspicuous irregularities ×: Conspicuous irregularities in cell state ○: Uniform independent cells Δ: Partial cell communication ×: Cell communication is significant, voids

[0048]

[Table 1]

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, the appearance before heat treatment is poor, but the methyl methacrylate-based copolymer has a specific viscosity of 2.9. It can be seen that when the above-mentioned materials are used, the appearance of the molded product before the heat treatment is very good and the expansion ratio is higher than that of the comparative example. Further, the compression set before the heat treatment is as large as 37 to 62% even in the example, but by performing the heat treatment at 70 ° C for 24 hours, it is lowered to 18 to 40%, which is a value equivalent to that of EPDM. I understand that it is possible.

Examples 11 to 17 and Comparative Examples 4 to 6 The compositions shown in Table 2 were used and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0051]

[Table 2]

From the results shown in Table 2, when the heat treatment temperature is low,
If the compression set cannot be reduced and conversely it is too high at 130 ℃,
It can be seen that not only the compression set cannot be reduced, but also the appearance of the molded product deteriorates. Furthermore, heat treatment time
It can be seen that the compression set cannot be reduced if it is too short, 0.2 hours. On the other hand, when the heat treatment time is 0.5 hours or more and the heat treatment temperature is 70 to 100 ° C, the compression set can be significantly reduced.

[0053]

EFFECTS OF THE INVENTION The soft vinyl chloride foamed molded product of the present invention is characterized in that it has a uniform expansion of cells and excellent independence while having a foaming ratio of 1.2 times or more, and has a small permanent set. .

Therefore, it is possible to obtain a soft vinyl chloride foamed molded product which is excellent in sound insulation properties, vibration isolation properties, heat insulation properties, protection properties, sealing properties and cushioning properties. Furthermore, the extrusion molding method makes it possible to inexpensively and easily produce a molded product having an excellent appearance, and can be sufficiently used even in the fields where only foams of EPDM and polyurethane rubber have been conventionally used. it can.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a tip cross-sectional shape of a die for extrusion molding of a seal member for automobile parts for evaluating compression set of a soft vinyl chloride resin composition foam molded article.

FIG. 2 is an explanatory diagram showing a method of measuring compression set using a test piece manufactured using the mold shown in FIG.

Claims (1)

[Claims] 1. 100 ml of benzene containing 100 parts by weight of vinyl chloride resin, 5 to 150 parts by weight of acrylonitrile-butadiene rubber dissolved in methyl ethyl ketone in an amount of 5 to 90% by weight, and 100 ml of benzene containing 0.4 g of a copolymer containing methyl methacrylate as a main component. Expansion ratio molded from 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 measured at 30 ° C. and a plasticizer of 20 to 200 parts by weight. Flexible vinyl chloride foamed molded product with 1.2 to 2.5 times and permanent strain of 15 to 40 % .