JPS6236434A - Crosslinked polyvinyl chloride resin foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a cross-linked chlorinated resin that has excellent vacuum formability, heat resistance, thermal adhesion, especially high frequency sealing properties and compression recovery properties, and has no plasticizer bleed-out. The present invention relates to a vinyl resin foamable composition.

[Conventional technology]

Conventionally, crosslinked vinyl chloride resins have been widely used in the production of flame-retardant foams in many fields such as furniture, automobile interior materials, and air conditioners due to their excellent flame retardancy and mechanical properties.

However, in order to produce a flexible vinyl chloride resin foam (hereinafter referred to as PVC foam) with a high expansion ratio, there are technically difficult problems such as crosslinking and plasticization of the PVC foam.

In other words, when producing PVC foam using a decomposable blowing agent, crosslinking is necessary because it is necessary to increase the melt viscosity of the polymer to a viscosity suitable for generating bubbles. The reason why the expansion ratio of thermally crosslinked PVC foam is extremely low, 2 to 3 times, is because the melt viscosity of the polymer rapidly decreases during the foaming process, making it impossible to maintain the original shape of the sheet, and the decomposition gas of the blowing agent is released. This is said to be due to the fact that the foam escapes from the sheet surface, making it impossible to increase the foaming ratio.

Special Publication No. 42-18828 and Special Publication No. 1387-1973
Each publication No. 4 describes that a foaming agent is mixed with PVC, the mixture is formed into a sheet, and the resulting sheet is heated and foamed while sliding it on a support plate with a smooth surface to form a foam. Although a manufacturing method has been proposed, since this foam is non-crosslinked, it cannot be used as an interior material for automobiles by heat processing.

Also, Special Publication No. 39-223370 and Special Publication No. 41-
No. 12632 discloses that PVC, polyisocyanate, a blowing agent, an unsaturated acid anhydride, a polymerizable monomer, and a halogenated saturated hydrocarbon are kneaded, this mixture is filled into a pressure-resistant mold, and the mixture is pressed under a high-pressure press. The polymer is heated and pressurized to gel the polymer and the blowing agent is decomposed, and then heated again with hot water or steam to produce a foam. Although a method has been proposed,
Since the foam obtained by such a method is limited to a batch method, productivity is low, resulting in high product cost and poor efficiency. In this method, when crosslinking and foaming are performed under normal pressure, the blowing agent decomposes before crosslinking progresses, so the decomposed gas is no longer contained in the molten polymer as bubbles and escapes to the outside, causing foaming. It ceases to form a body. Therefore, crosslinking is carried out under heating and pressure, and foaming is limited to heating under normal pressure.

On the other hand, as a continuous method for producing crosslinked PVC foam, electron beams are used, as proposed in various publications such as Japanese Patent Publication No. 46-18620, Japanese Patent Publication No. 4B-4863, and Japanese Unexamined Patent Publication No. 1729-1982. A cross-linking method is usually employed. However, this crosslinking method using an electron beam has a problem in that dehydrochlorination occurs during decomposition that competes with the crosslinking reaction, resulting in coloring of the foam. The coloring of this foam becomes stronger as the electron beam irradiation energy increases, from brown to black. properties), thermal adhesion, especially high-frequency sealing properties, compression recovery properties, heat resistance, processability, etc., did not satisfy practical performance.

Furthermore, blends of low-molecular plasticizers have the problem that the low-molecular plasticizers tend to bleed out from the foam. Attempts to solve this problem have been proposed, but the ethylene/vinyl acetate/carbon oxide copolymer used in this invention is expensive and difficult to knead and disperse with PVC resins. Difficult or
It has the disadvantage of causing various collocations due to deacetic acid removal.

[Problem that the invention seeks to solve]

The object of the present invention is to provide Pv containing the above-mentioned vinyl chloride as an essential component.
The object of the present invention is to improve the vacuum formability, heat resistance, high-frequency sealability, and compression recovery properties that have been considered to be shortcomings of C foams, and to provide a crosslinked PVC foam without plasticizer bleed-out.

[Means for solving problems]

The purpose of the present invention is to use vinyl chloride resin ■, ethylene,
Alkyl acrylate copolymer or ethylene/acrylic acid copolymer (B) and propylene copolymer (
This can be achieved by a crosslinked vinyl chloride resin foam consisting of C).

The foam of the present invention is a blend polymer containing a vinyl chloride resin (A), an ethylene/alkyl acrylate copolymer or an ethylene/acrylic acid copolymer (B), and a propylene copolymer (Q as an essential component). It consists of

these essential ingredients.

■ and 0 are 10 to 30 parts by weight, 5 to 50 parts by weight, and 10 to 50 parts by weight, respectively, based on the total amount of the polymer blend constituting the foam.
It is desirable that the amount is within the range of 70 parts by weight.

The vinyl chloride-based resin particles constituting the foam of the present invention include polyvinyl chloride, various known copolymers containing vinyl chloride as a main component, ethylene-vinyl acetate copolymers, and acrylic rubber grafted with vinyl chloride. Examples include polymerized polymers. This prisoner component is an essential component as a vinyl chloride resin foam, and its blending ratio is 10 to 401i! It is necessary to contain i parts, preferably in an amount ranging from 20 to 30 parts. In other words, if the content of the binder component is less than 10 parts, it is undesirable because the high-frequency sealing properties peculiar to PVC foam will be inferior, and if it is more than 40 parts, the proportion of PVC resin in the whole will increase, making it less compatible. .

This is not preferable because it worsens dispersion.

The ethylene/alkyl acrylate copolymer and ethylene/acrylic acid copolymer of component (1) constituting the foam of the present invention have an alkyl acrylate copolymerization amount of 2.
~30% by weight, a melt flow rate (MFM) of 1 to 50 g/10 min, and a copolymerized amount of acrylic acid and ethylene furkyl acrylate copolymer of 5 to 30% by weight, and an MFI of 1 to 50% by weight. There is an ethylene-acrylic acid copolymer that has a speed of 50/10 minutes. The mixing ratio of component (1) is 5 to 50 parts by weight, preferably 20 to 40 parts by weight. If the amount of component (2) is less than 5 parts, the compatibility between PVC resin and polypropylene resin will deteriorate It is not preferable, and if it exceeds 50 parts, heat resistance decreases, which is not preferable.

In addition, the foam of the present invention is composed of a propylene/ethylene copolymer (Q is a propylene/ethylene copolymer, especially a copolymerized amount of ethylene of 2
~8% by weight, MFI of 0.5~10g/10min, infrared absorbance ratio (hereinafter referred to as IR absorbance ratio) CLr5
o/l1140) ratio or (I726/1846
) ratio of 0.02 to 0.3, specifically propylene/α-olefin copolymers and propylene/ethylene/α-olefin terpolymers. The blending ratio of this component 0 is preferably 10 to 70 parts by weight, preferably 30 to 50 parts by weight. If the blending amount of component 0 is less than 10 parts, heat resistance decreases, which is not preferable, and 70 parts by weight. Exceeding this is not preferable because the high frequency sealing properties of the PvC foam deteriorate.

In the foam of the present invention consisting of the three components (A), (B) and 0, the degree of crosslinking is preferably in the range of 10 to 60%, preferably 20 to 40%, and the expansion ratio is The range is 5 to 50 times, preferably 10 to 40 times.

If the degree of crosslinking is lower than 10%, it is undesirable because the decomposed gas of the blowing agent escapes to the outside, resulting in disadvantages such as not being able to achieve a significantly high expansion ratio. This is not preferable because it becomes impossible to confine the decomposed gas of the agent in the small-diameter cells, resulting in the formation of coarse bubbles. If the foaming ratio is lower than 5 times, the cushioning properties of the foam will not be satisfactory, and if it exceeds 50 times, the cell membrane will become very achy and the foam will not be able to maintain its strength, which is not preferable.

Hereinafter, one embodiment of the method for producing a crosslinked vinyl chloride resin foam according to the present invention will be described.

A vinyl chloride resin having the above copolymer composition and an ethylene/alkyl acrylate copolymer or an ethylene/alkyl acrylate copolymer
To 100 parts by weight of a blend polymer consisting of an acrylic acid copolymer (B) and a propylene copolymer (C), a polyfunctional monomer preferably having at least two vinyl groups as a crosslinking agent, For example, 1 to 10 parts by weight, preferably 2 to 6 parts by weight, of divinylbenzene, triacryl formal, trimethylpropane triacrylate, triallylmeritate, etc., and known thermally decomposable blowing agents such as azodicarbonamide, dinitrosopentamethylene, etc. Tetramine or the like is mixed in an amount ranging from 5 to 20 parts by weight, preferably from 5 to 15 parts by weight, and the mixture is molded, for example, into a sheet, while being maintained at a temperature at which the crosslinking agent and blowing agent described above do not decompose. This formed sheet material is subjected to any known method such as an ionizing radiation crosslinking method or a chemical crosslinking method to obtain a crosslinking degree of 15 to 60%, preferably 20 to 4.
Crosslink to 0%.

More specifically, in the case of the ionizing radiation crosslinking method, α, β, γ, X-rays, electron beams, neutron beams, etc. are used as high-energy rays, and a high-energy electron beam irradiation machine is usually used. The sheet is crosslinked by irradiating the sheet with an electron beam at a dose of ~50 Mrad. Instead of this radiation irradiation, it is also possible to add an ultraviolet sensitizer such as benzophenone and crosslink by irradiating ultraviolet rays.

In addition, in the case of chemical crosslinking method, dicumyl peroxide,
Cross-linking methods using organic peroxides such as tertiary butyl peroxide, and silane cross-linking methods in which graft cross-linking is performed by kneading vinyl silane such as vinyltrimethoxysilane with these cross-linking agents, and then cross-linking by siloxane condensation reaction. It can be applied as appropriate.

The thus obtained crosslinked molded product is heated in a hot air atmosphere or on a chemical bath to rapidly decompose the foaming agent contained within the molded product, thereby converting it into a foam having an expansion ratio within the above range.

In addition, various polymers such as polyethylene, ethylene-vinyl acetate copolymer, polybutylene, chlorinated polyethylene, etc. may be added to the vinyl chloride resin composition used for producing the foam of the present invention, within a range that does not impair the purpose of the present invention. A small amount of up to 10% by weight can be added and mixed, and if necessary, lubricants, antioxidants, ultraviolet absorbers, colorants, antistatic agents, antistatic agents, etc. Fuel agents, various inorganic substances that impart other properties, etc. can be added for desired purposes.

Furthermore, the crosslinked PVC resin foam of the present invention can be laminated with an adhesive applied to at least one surface thereof by corona discharge treatment, coating, etc., in order to improve its processability. Various processing techniques can be used, such as laminating foam sheets, other foam sheets, or metal foils, or imparting a composite structure by extrusion lamination.

〔Effect of the invention〕

The crosslinked vinyl chloride resin foams of the present invention thus obtained are various foams with expansion ratios ranging from 5 to 50 times, and a drawing ratio (depth L)/diameter (D) of 0. 5
Vacuum formability as above, heat resistance with shrinkage rate of 3% or less when heated at 110°C for 1 hour, excellent thermal adhesion to polyethylene sheets, polypropylene sheets, other vinyl chloride sheets and foams, especially excellent It has excellent high-frequency sealing properties and compression set properties, as well as excellent cushioning and heat insulation properties, and there is no bleed-out of additives, especially plasticizers, so it is suitable for various packing materials, adhesive tape bases, mat substrates, and automobiles. Its excellent performance can be utilized in many applications such as interior parts, other clothing, and building materials.

Therefore, the PVC foam obtained by the present invention:
It has excellent flexibility, high strength, and is resistant to creases, and can be used in many applications that require a soft feel, including automotive interior materials. In particular, since the PVC resin foam of the present invention can be given any pattern by high-frequency welding, its usefulness is greatly increased in fields such as automobile interior parts that require plasticity.

Furthermore, since the foam of the present invention has lower rebound resilience than polyolefin foam, it is suitable for underlaying artificial turf for sports where it is desired that the ball rebounds close to the ground. It is extremely useful as an underlay or backing material for carpets due to its cushioning properties, resistance to slipping on floors, and hygiene. Other uneven parts,
Because it has good performance such as good ability to follow curved surfaces and melting resistance, it can be used as an adhesive tape for joints in building materials and as a level difference absorbing material.

The effects of the present invention will be explained in more detail below based on Examples.

In the present invention, vacuum formability, gel fraction, heat shrinkability, heat sealability, high frequency sealability, compression set, apparent expansion ratio, etc. are values measured by the following method.

(1) Vacuum formability When the foam sample is heated under the optimum heating conditions and straight-molded using a vacuum forming machine equipped with a vertical cup-shaped die with diameter and depth L, the foam may break. Vacuum formability was examined using the L/D limit at which the material could be stretched into a cup shape.

Vacuum formability L/D...0.5 or more: ○L/D
...0.5 or less: × (2) Collect approximately 0.2 g of shredded gel fraction foam and weigh it accurately (
This value is designated as W work). After immersing this foam in tetralin at 135°C for 3 hours, the insoluble portion was taken out and washed with methanol, air-dried and vacuum-dried, and then immersed in 20ml of dimethylformamide at 110°C for 2 hours.
The remaining insoluble portion is taken out, washed with methanol, air-dried and vacuum-dried, and then precisely weighed (this value is designated as W2).

The gel fraction is calculated from the values of W and W2 using the following formula.

Gel fraction (%) = 100·W 2 / W 1 Judgment was made from this gel fraction value according to the following criteria.

20 with a gel fraction of 15-60% Gel fraction outside the above range: × And so.

(3) Heat shrinkage The heat shrinkage rates in the vertical, horizontal, and thickness directions due to heat treatment are shown in accordance with the measurement method specified in JIS-6767. Specifically, a measurement sample (foam) is marked with square marks of 10 cm both vertically and horizontally to measure its thickness, and then heat treated in a hot air oven at 90° C. for 22 hours. After cooling to room temperature, the vertical, horizontal and thickness dimensions were measured, and the following judgment was made based on the magnitude of dimensional change (thermal shrinkage rate) due to this heat treatment.

Heat shrinkage rate: Within ±3.0 - 〇〇[Pass] Heat shrinkage rate
Exceeding ±5.0: × The measurement of the dimensional change due to the heat treatment was performed 5 to 10 times and determined.

(4) Compression set (S) Measured according to the measurement method specified in JIS-6767-1976.

A 5cI11 x 5cIl square sample with a thickness of approximately 25++
They were stacked so as to have a thickness of n, and left for 22 hours under a compressive strain of 25% of the total thickness (to). Thereafter, the thickness (t) after releasing the compressive strain and leaving it at room temperature for 24 hours was measured, and the compression set (S) was calculated according to the following formula.

S (%) = 100X (to -t+) / t.

Compression set (S) within 5%: O 5%
Those above: rated as ×.

(5) Apparent expansion ratio This value is expressed as the reciprocal of the apparent density of the foam. Cut the foam into a 10 cm x 10 aa square, measure the weight and thickness, and divide this weight by the volume to obtain the value per unit volume. Weight (
g/cd).

Items with an apparent foaming ratio of 5 to 50 times20 〃　Other than the above: × And so.

(6) Overall Judgment Those that satisfied all of the criteria in (1) to (4): ○; those that were unsatisfactory in at least one item: ×.

Example 1 25 parts by weight of vinyl chloride resin, 25 parts by weight of ethylene-ethyl acrylate copolymer with MFR of 6 g/10 minutes containing 18% ethyl acrylate (manufactured by Nippon Uni-Riki Co., Ltd.) and 4% ethylene content. , MFR is 1.2 g/
10 minutes, I *xo / I 114 (C) is 0.14
50 parts by weight of ethylene propylene copolymer (manufactured by Mitsui Toatsu Chemical Co., Ltd.), 2 parts by weight of trimethylpropane triacrylate (manufactured by Osaka Organic Co., Ltd.), 12 parts by weight of azodicarbonamide as a foaming material, and 1 part by weight of basic lead sulfate. .5 parts by weight and 1.5 parts by weight of Ca/Zn composite stabilizer were mixed and dispersed.
It was extruded using a 401 m extruder heated to 70 degrees and formed into a sheet with a thickness of 1.6 va and a width of 250 m.

The obtained sheet was irradiated with an electron beam of 3 Mrad to cause crosslinking, and then heated on a silicone bath heated to 220°C.
It was foamed to obtain a foam having the properties shown in Table 1.

Example 2 In Example 1, a vinyl chloride-acrylic acid copolymer resin with a copolymerized amount of acrylic acid of 8% was used instead of the vinyl chloride resin, but the foam was compounded in the same manner as in Example 1. A composition was prepared and foamed to obtain a foam having the properties shown in Table 1.

Example 3 In Example 2, 1.5 parts by weight of dicumyl peroxide was blended with the blended polymer and kneaded for 5 minutes using two rolls at 160°C. The resulting compound was formed into a sheet with a thickness of 1.9 fi using a pressure press heated to 160°C, and this sheet was heated at 165°C for 10 minutes to crosslink, and then placed in a silicone bath heated to 220°C. Foamed on top. The properties of the obtained foam are shown in Table 1.

Comparative Example 1 A blend polymer consisting of 10 parts by weight of vinyl chloride/acrylic acid copolymer, 40 parts by weight of ethylene/ethyl acrylate, and 50 parts by weight of ethylene propylene copolymer, 12 parts by weight of azodicarbonamide, and 2 parts by weight of basicity Lead sulfite was mixed and dispersed, introduced into a 40 m extruder heated to 170°C, and extruded to produce a sheet with a thickness of 1.6 days and a width of 250 fi.

After irradiating this sheet with an electron beam of 5 Mrad, 220
Foaming was carried out on a silicone bath heated to °C.

The physical properties of the obtained foam are shown in Table 1.

Comparative Example 2 A blend polymer consisting of 30 parts by weight of vinyl chloride/acrylic acid copolymer and 70 parts by weight of ethylene/propylene copolymer was added with 12 parts by weight of azodicarbonamide, 2 parts by weight of basic lead sulfite, and 6 parts by weight. Divinylbenzene was mixed and dispersed, and introduced into a 40 Tsuru extruder heated to 170°C.
A sheet with a thickness of 1.6 fins and a width of 250 ta was produced by extrusion.

After irradiating this sheet with an electron beam of 6 Mrad, 220
Foaming was carried out on a silicone bath heated to °C.

The physical properties of the obtained foam are shown in Table 1.

(Margins below this page) Table 1 (Note): Thermal adhesiveness A indicates the adhesiveness to polyethylene/polypropylene sheet foam, and the thermal adhesiveness B indicates the adhesiveness to vinyl chloride resin sheet foam. , the case where the foam of the present invention was torn was indicated by a Q mark, and the case where it was peeled from the adhesive interface was indicated by an x mark.

High-frequency sealability indicates the high-frequency sealability for the vinyl chloride resin sheet foam, and similarly to thermal adhesiveness, the case where the foam of the present invention is torn is indicated by an ○ mark, and the case where it is peeled from the adhesive interface is indicated by an X mark. It was displayed in

Claims (2)

[Claims] (1) Crosslinked vinyl chloride resin foam consisting of vinyl chloride resin (A), ethylene/alkyl acrylate copolymer or ethylene/acrylic acid copolymer (B), and propylene copolymer (C) . (2) In claim 1, the vinyl chloride resin (A) is 10 to 40 parts by weight, and the ethylene/alkyl acrylate copolymer or ethylene/acrylic acid copolymer (B) is 5 to 50 parts by weight. A crosslinked vinyl chloride resin foam containing 10 to 70 parts by weight of the polymer portion and propylene copolymer (C).