JPS6086130A - Manufacture of foamed vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain the titled foamed article having excellent dimensional stability, etc., by mixing a specific amount of a base resin such as vinyl chloride resin homogeneously with a mixed foaming agent which is a mixture of aliphatic hydrocarbons, etc. having boiling point of lower than a specific level and having a molar-average molecular weight, etc. within specific ranges, and carrying out the extrusion foaming of the composition. CONSTITUTION:(A) A base resin obtained by mixing 85-30(wt)% vinyl chloride resin with 15-70% styrene resin and/or acrylic resin (e.g. methyl methacrylate resin) is mixed homogeneously with (B) a mixed foaming agent composed of a mixture of one or more aliphatic hydrocarbon and halogenated aliphatic hydrocarbon each having a boiling point of <=60 deg.C, having a molar-average molecular weight of <=120 and molar solubility coefficient of >=7.6, containing <=40mol% foaming agent component having higher rate of permeation of the vapor to the base resin than air, and containing <=40mol% foaming agent component having a boiling point of >=40 deg.C, and the mixture is subjected to the extrusion foaming to obtain the objective foamed article. EFFECT:It has uniform closed cell structure, and has excellent dimensional stability, compression strength, steam permeability, and self-extinguishing property.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vinyl chloride resin foam, particularly a vinyl chloride resin foam with a uniform and independent cell structure and a high expansion ratio, which has improved dimensional stability, compressive strength, and water vapor permeability. Rate, 9
The object of the present invention is to provide a method for manufacturing a foam having a large cross-sectional area and extremely excellent flame-extinguishing properties.

Conventionally, a method for producing a hard vinyl chloride resin foam with a high expansion ratio by extrusion foaming is disclosed in Belgian Patent No. 647.34.
5, Japanese Patent Publication No. 5s-s, 1Ili32, Japanese Patent Publication No. 58-87
135 mag is known. However, according to the inventor's additional tests, the foam obtained by the manufacturing method shown in Belgian patent 647.345 is a foam with a low closed cell ratio, or even when the closed cell ratio is high. The dimensions change over a long period of time.

Foams whose dimensions change over a long period of time need to be stored for a long period of time until the product dimensions stabilize, and foams with a low closed cell ratio have poor compressive strength, water vapor permeability, etc., and are therefore not preferred. do not have.

Also, JP-A-58-84832, JP-A-58-8713
The method shown in 5 involves adding an aromatic, ether, ketone, or ester organic solvent in addition to a normal blowing agent to inject the organic blowing agent into the resin in the extruder. The purpose of this is to reduce and stabilize the injection pressure of the organic blowing agent and to improve the dispersion efficiency of the organic blowing agent. That is, by plasticizing and swelling the vinyl chloride resin with an aromatic or other organic solvent, the blowing agent can be easily dispersed and dissolved in the resin.

However, the foam obtained in this way has problems such as a decrease in compressive strength and heat resistance, and also emits an unpleasant odor of organic solvent, so it is not preferable.

The inventor has a uniform, independent cell structure, dimensional stability,
As a result of intensive research into whether it is possible to produce a polyvinyl chloride resin foam with a high expansion ratio and excellent compressive strength and water vapor permeability, we found that it is possible to produce a polyvinyl chloride resin foam that is a mixture of styrene resin and/or acrylic resin. By skillfully selecting and combining the blowing agents used, the above problems were solved and the present invention was achieved.

In other words, the present invention combines a vinyl chloride resin, a styrene resin, and/or an acrylic resin with two or more components selected from aliphatic hydrocarbons and aliphatic halogenated hydrocarbons having a boiling point of 60°C or less. (1) The base resin contains 85 to 30% by weight of vinyl chloride resin, styrene resin and (
or) consisting of 15 to 70% by weight of acrylic resin, (
2) The mixed blowing agent has (a) a molar average molecular weight of the mixed blowing agent of 120 or less, (b) a molar average solubility coefficient (sp value) of the mixed blowing agent of 7.6 or more, and f-'3 The amount of a blowing agent component whose gas permeation rate through the resin is higher than that of air is 40 molar or less in the mixed blowing agent, and (2) the blowing agent component with a boiling point of 40°C or higher in the mixed blowing agent is 40 molar or less. This is a method for producing a vinyl chloride resin foam.

According to the method of the present invention, the required amount of the mixed organic blowing agent can be easily and uniformly dispersed and dissolved in the heated resin composition in the extruder without using an organic solvent. It is possible to produce a vinyl chloride resin foam having a uniform and independent cell structure and having a high expansion ratio and excellent dimensional change rate, compressive strength, water vapor permeability, etc. Furthermore, the resulting foam has a large cross-sectional area, which is extremely advantageous when producing a foam with a large cross-sectional area.

The present invention will be explained in detail below.

The vinyl chloride resin used in the present invention is preferably a homovinyl chloride resin, which has excellent thermal stability, tensile strength, heat resistance, and low cost. Brene (9) containing small amounts of vinyl chloride copolymers, graft copolymers, and resins that are compatible with vinyl chloride resins, such as vinylidene chloride, ethylene-vinyl acetate copolymers, and chlorinated polyethylene.
Polymer is also acceptable. Additionally, mixtures of these are also useful.

Styrenic resins are mainly composed of styrene, and copolymerizable with acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, and their esters, as well as comonomers such as maleic acid, fumaric esters, and maleic anhydride. It is a copolymer with one or more components selected from the group, and also includes a copolymer containing a rubber component.

Mixtures of these are also useful. The acrylic resin is a resin whose main R content is a methacrylic ester such as methyl methacrylate or ethyl methacrylate, or an acrylic ester such as methyl acrylate or ethyl acrylate. These styrene resins and acrylic resins may be used in combination.

It uniformly promotes the gelation of vinyl chloride resin and facilitates the flow of the gel in the extruder, but it does not have the effect of helping bubble growth and stabilization during foaming, and the closed cell ratio of the resulting foam is low. Moreover, even if it is used in excess of 70% by weight, no special effect can be obtained by adding a large amount, but rather the characteristics of the resulting foam as vinyl chloride, for example, This is because the extinguishability is lost.

The reason why the amount of styrene resin and/or acrylic resin used in the present invention is 15 to 70% by weight is as follows.
Less than 15% by weight, styrenic resin and/or
The flow modification effect of acrylic resin on vinyl chloride resin, that is, stabilizers, lubricants, plasticizers, flame retardants, foam regulators, ultraviolet absorbers, antioxidants, antistatic agents, You may use pigments etc. as appropriate.

The blowing agent used in the present invention is selected from aliphatic hydrocarbons with a boiling point of 60°C or less and aliphatic halogenated hydrocarbons with a boiling point of 60°C or less. For example, aliphatic hydrocarbons include propane (s, p value = 6.4) butane (6, s
), isobutane (6,s), 1-butene (6,7),
2-butene, cis(7,2), 1,3-butadiene(7
,1), pentane (7,0), isopentane (6,7)
, neopentane (63), 1-pentene (7,1),
2-pentene, cis(7,a), 2-pentene, trans(7,3), halogenated hydrocarbons include methyl chloride (9,7), ethyl chloride (9,2), propyl chloride (
8,s), isopropyl chloride (s,i), methylene chloride (9,7), ethylidene chloride (8,9), vinyl chloride (7,8), trichlorofur:to)ethane (7,
6), dichlorodifluoromethane (S, S), dichlorofluoromethane (aa), chlorodifluoromethane (c
t, s), fluorotrifluoromethane (4,8), trichlorotrifluoroethane (7,3), dichlorotetrafluoroethane (6,2), chlorodifluoroethane (
6,8), difluoroethane (7,0), dibromotetrafluoroethane (7,0), and the like.

The solubility coefficient (sp(Ij) written in parentheses is Polym
erHand Book 8econd Bditio
n, J, 13RANDRUP and BJLIMM
The values listed in the book written by EROUT (published in 1974) are entered, and if they are not listed in the above document,
Other literature values were used, or the value at 25°C calculated by the formula below was used.

△H: Evaporation latent number ca//imo/ R=Gas constant cal/mo!・The molar average solubility coefficient (sp value) referred to in the present invention is 0, absolute temperature °, and the sp value of each component of the mixed blowing agent multiplied by its malt, and the sum of the products is calculated to the second decimal place. If you divide 4 to 5 people, say the value you got.

The molar average molecular weight in the present invention refers to the value obtained by multiplying the molecular weight of each component of the mixed blowing agent by its molar ratio, summing the products, and rounding the numbers to the nearest decimal place.

The blowing agent used in the present invention is a mixture of one or more components each selected from aliphatic hydrocarbons with a boiling point of 60°C or less and aliphatic halogenated hydrocarbons, and has a boiling point of 60°C or less.
If a blowing agent with a temperature higher than 0.degree.

In the present invention, the essential conditions for combining these blowing agents are as follows: (a) The molar average molecular weight of the blowing agent is 120 or less, and (b) The molar average solubility/ξ rameter (8P value) of the blowing agent is 7.
6 or more and r-t The amount of the blowing agent that has a faster gas permeation rate than air is 40 molti or less, and) the amount of the blowing agent with a boiling point of 40° C. or higher is 40 molti or less.

If the molar average molecular weight of the blowing agent exceeds 120, it will be necessary to inject a large amount of the blowing agent to obtain a low-density foam. Holes that reach the center are generated, making it difficult to obtain a good foam.

Therefore, the molar average molecular weight of the blowing agent used in the present invention needs to be 120 or less.

Next, the reason why the molar average sp value of the blowing agent must be 7.6 or more is that if a mixed blowing agent with a molar average sp value of less than 7.6 is used, the resulting foam will have a cell diameter of 0.
This is because the closed cell ratio decreases and the skin becomes rough due to the extremely fine but unrestricted distribution of the foam, which is less than 1 m in diameter. This is because the area of the cut surface (hereinafter abbreviated as cross-sectional area) is less than half the cross-sectional area of the foam when a mixed foaming agent with a molar average sp value of 7.6 or more is used.

This means that when manufacturing a foam with a large cross-sectional area,
This means that it can be produced satisfactorily with a small extruder, which means that it is very advantageous in terms of equipment.

The reason why the above phenomenon occurs when a mixed blowing agent with a molar average SP value of less than 7.6 is used is not clear, but vinyl chloride resin is a highly polar resin, and the molar average SP value is 7.6.
Even if a mixed foaming agent of less than It is thought that there is.

The reason why the amount of the blowing agent that has a higher gas permeation rate than air through the resin must be 40 molt or less is that if a blowing agent that has a higher gas permeation rate than air is used in an amount exceeding 40 molt, the dimensional change of the foam may occur. This is because the ratio is large, and also because it takes a long time until the dimensions become stable. (See Figure 1) More preferably, the amount of the blowing agent that permeates faster than air is 30 molt or less. In this case, the dimensional change rate is even smaller and the dimensions are stable in a short time. do.

Examples of blowing agents having a higher gas permeation rate than air are aliphatic chlorinated hydrocarbons such as methyl chloride, ethyl chloride, and methylene chloride.

The reason why the amount of the blowing agent component with a boiling point of 40°C or higher must be 40 mol or less is that if it is used in excess of 40 mol, the foam extruded from the die will cause abnormal shrinkage immediately after extrusion. It is from.

The amount of the mixed organic blowing agent to be used is determined as appropriate, taking into consideration the molar average molecular weight of the blowing agent and the density of the foam to be obtained.

To illustrate the composition of a more practical mixed organic blowing agent that satisfies the constituent requirements of the present invention, the first component is an aliphatic chlorinated hydrocarbon, such as methyl chloride, ethyl chloride, methylene chloride, etc.; The amount used is 10-40 mol. It is preferable to use trichlorofluoromethane as the second component, and the amount y (molti) of this second component to be used is according to the following formula according to research by the present inventors.

(Yanagi-20)≦y≦(too −x)
The third component is the remainder after reducing the amount of mole used in the second component. Difluoromethane and chlorodifluoromethane.

The method of the present invention is preferably an extrusion foaming method, in which a vinyl chloride resin and a styrene and/or acrylic resin are fed into an extruder, and then the resin is heated and gelled in the extruder. The organic mixed foaming agent is press-fitted and kneaded to uniformly disperse and dissolve the organic mixed foaming agent in the resin, and then the resin is uniformly cooled to a temperature suitable for foaming. It is extruded through a shaped die into the atmosphere or under reduced pressure.

In the method of the present invention, that is, the method of using vinyl chloride resin, styrene resin, and (still) acrylic resin in combination with an organic mixed blowing agent, the injection pressure of the blowing agent is low and there is little pressure fluctuation. Furthermore, it also has the effect of easily dissolving the blowing agent into the resin.

The reason for this is probably that in addition to the improved fluidity of the styrene resin or acrylic resin, the solubility of the blowing agent itself in the resin is significantly improved by skillfully selecting and combining blowing agents. I don't think it's because I am.

The present invention will be specifically explained below using Examples and Comparative Examples, but before that, the method and criteria used for evaluating foams in the present invention will be explained below.

1. Foam density Measured according to JI8 A9511.

2 Closed cell ratio Measured by the air vicinometer method described in ASTM D2856.

3. Cross-sectional area of foam Color the cross-section of the foam cut perpendicularly to the extrusion direction with ink, press it onto graph paper with 5-blend intervals, copy the cross-sectional shape onto the graph paper, and count the squares colored with ink. The cross-sectional area of the foam was calculated. However, the area of a fully colored square is 0.25c++7 The area of a partially colored square is 0.
．． Calculated as 125J.

4. Compressive strength Measured according to JIS A9514.

5. Water vapor transmission rate Measured according to ASTM E-96E method.

64 Flammability (self-extinguishing flame retardant) Measurement and evaluation were performed according to JI8 A9511.

7. Dimensions of the foam: Length 1200m+, width 100+m from the foam immediately after extrusion
n, thickness 25. Cut out the test pieces and place them at equal intervals in the width direction.
The length of 1000+w+ was measured and marked at several points.

The foam was left in a constant temperature room at 20° C., its length was measured, and the average value of the measurements at three locations was taken as the length of the foam.

8 Cell Shape Others A: Uniform bubble shape of 1.0-tpan or less, and smooth skin.

B: Although the bubbles are 1.0 mm or less, there are large holes here and there that penetrate to the epidermis.

0: Very fine bubbles of 0.1 mm or less are formed, but the bubbles are unevenly distributed, and the epidermis is rough.

Examples 1 to 5, Comparative Example 6.7 The first extruder was equipped with a screw with a diameter of 50 mm and L/D = 28, consisting of four sections: a feeding section, a compression section, a metering section, and a mixing section. A blowing agent injection hole is provided at a position between the measuring section and the mixing section of the cylinder. In addition, this extrusion mode can be carried out using another 6
It is connected to a 5φ extruder, and a die having a rectangular opening of: 2+g+X50wn is provided at the outlet of the second extruder.

Table 1 shows the resins (A-F) used in the experiment. Further, Table 2 shows the blowing agents (1 to 10) used and their molecular weights, boiling points, sp values, and comparisons with air in gas permeation rates.

First, to 100 parts by weight of the vinyl chloride resin listed in Table 1, 2nZf parts of soot stabilizer, 0.5 parts by weight of calcium stearate, and 05 parts by weight of paraffin wax were added and mixed in a Henschel mixer.

Next, a styrene or acrylic resin listed in Table 1 was added to the above vinyl chloride resin.
Add 0.2 parts by weight of talc to the parts by weight and mix in a Henschel mixer, then put into a conch/ξ-yoshi extruder, and while extruding, foam a mixed blowing agent with the following composition selected from Table 2. After injecting the agent through the injection port and mixing thoroughly,
It was cooled uniformly, extruded from a gooey, and foamed. The extrusion conditions are described below.

(Blowing agent) Mole average molecule i#95 Mole average sp value 8.1 (Extrusion conditions) Supply section 140-150°C Compression section 160-180°C Measuring section 170-190°C Mixing section 160-180°C Gui 115-125 °C Resin temperature at die part 116-120 °C Extrusion rate 35 to 9/hr Extrusion foaming under the above conditions, and the density, closed cell ratio, compressive strength, water vapor permeability, and combustibility of the obtained foam were measured. The results are shown in Table 3.

From a comparison of Example 1.4 and Comparative Example 6.8, it was found that when the amount of styrene resin or acrylic resin used was less than 15% by weight, the closed cell ratio, compressive strength, and water vapor permeability of the resulting foam were poor. Furthermore, from a comparison between Example 3 and Comparative Example 7, it was found that when the amount of vinyl chloride resin used in the lid was less than 300 parts by weight, the combustibility of the resulting foam deteriorated.

Examples 9 to 15, Comparative Examples 16 to 23 The extruder used, extrusion conditions, etc. are the same as those described above.

The resins used are the following selected from Table 1. The resin was mixed with the same additives in the manner described above.

The foaming agents used were those listed in Table 2 in appropriate combinations.

Density of the foam obtained by extrusion foaming under the above conditions,
The closed cell ratio, cross-sectional area, compressive strength, water vapor permeability, and dimensional change were measured and the results are summarized in Table 4.

Comparative Example 16 shows that when a blowing agent with a boiling point exceeding 60° C. is used, the foam undergoes abnormal shrinkage (buckling) immediately after extrusion foaming.

A comparison between Example 9 and Comparative Examples 22 and 23 shows that when the molar average molecular weight of the blowing agent used exceeds 120, the closed cell ratio, compressive strength, water vapor permeability, etc. of the resulting foam decrease.

Extracting the necessary parts from Table 4, from a comparison of Example 14 and Comparative Example 20.21, the closed cell ratio, water vapor permeability, etc. of the foam obtained when the molar average sP value of the blowing agent used is less than 7.6. It is observed that the cross-sectional area decreases and the cross-sectional area decreases.

Extracting the necessary parts from Table 4, a comparison between Example 12.14.15 and Comparative Example 18.19 shows that the amount of blowing agent (methyl chloride in this case) used, whose gas permeation rate through the resin is faster than that of air. It is clear from FIG. 1 that the dimensional change rate of the resulting foam is small and the number of days required for the dimensions to become stable is short when the molarity is 40 molti or less, more preferably 30 molti or less.

Extracting the mantle from Table 4, a comparison of Example 13 and Comparative Example 17 shows that if a blowing agent with a boiling point of 40°C or more is used in excess of 40 molt, the foam will experience abnormal shrinkage (buckling) immediately after extrusion. Occur.

As is clear from the above Examples and Comparative Examples, the method of the present invention has little foam shrinkage after foaming, makes it easy to obtain a foam with a large cross-sectional area, and the obtained foam is highly foamed. It has a high closed cell ratio and is excellent in all properties such as compressive strength, water vapor permeability, and flame retardancy, making it an all-inclusive method with high industrial value.

Below margin

[Brief explanation of the drawing]

FIG. 1 shows the rate of dimensional change over time of the foam obtained by the method of the invention. Patent applicant Asahi Kasei Kogyo Co., Ltd. Procedural amendment (voluntary) January 7, 1980 Patent Office Commissioner Motoki Sugi Kazuo 1 Indication of the case 1981 Patent Application No. 194372 2 Name of the invention Vinyl chloride resin Process for producing foam a Relationship with the case of the person making the amendment Patent applicant 1-2-6-4 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture, “Claims” of the specification to be amended and [5. Contents of amendment (1) The scope of claims in the specification is corrected as shown in the attached sheet. (2) Page 2, line 6 “H647.645” is 1H64
7. Correct it as 345 J. (3) ``Patent 647.645'' in the second negative line 8 of the same is corrected to [Patent 647,345 j. (4) In the first line of page 4, ``and aliphatic'' is corrected to ``1 and aliphatic with a boiling point of 60°C or less''. (5) Delete the following line from page 6, lines 8 to 16: ``The delification of vinyl chloride resin---for example, the self-extinguishing property is lost.'' (6) Insert the following sentence after "that is," in the first line of page 7. ``The effect of uniformly promoting the delification of vinyl chloride resin and facilitating the flow of the del in the extruder, but also supporting the growth and stabilization of cells during foaming, was not achieved, and the closed cell ratio of the resulting foam was low. Moreover, even if it is used in excess of 70% by weight, no special effect can be obtained by adding a large amount, and rather, the characteristics of the resulting foam as vinyl chloride, such as self-extinguishing (Force) Correct the ``absolute temperature'' in the 4th line from the bottom of the 8th negative to ``T: Absolute temperature''. (9) Change "parameter" to "coefficient" on page 9, line 15 of the same page.
I am corrected. Q [Correct "reduced" to "reduced" in line 5 of page 16. (11) On page 17, line 17, "methyl salt" is corrected to "methyl chloride." az Page 20, line 4, "16" is corrected to "9". u'5 Same page 20, line 4 r 2.8 J to r2.7J
I am corrected. I, page 21, line 11, column 412, (%) [0,
Correct 7J to I' 0.6 J. (1) Column No. 5 of Table 2 on page 24, boiling point term r8.9
Correct J to [-29,8j] αQ Correct the molar average molecular weight term "95" in column 16 of Table 4, page 26, to [100J. Claims A base resin consisting of 85 to 60% by weight of a vinyl chloride resin, 15 to 70% by weight of a styrene resin and/or an acrylic resin, an aliphatic hydrocarbon with a boiling point of 60°C or less, and an aliphatic hydrocarbon with a boiling point of 60°C or less It is a mixture of more than one component selected from aliphatic) and 9-carbonated hydrocarbons, and has a molar average molecular weight of 120 or less and a molar average solubility coefficient (SP value) of 7.6.
In the above steps, the foaming agent component having a gas permeation rate higher than that of air through the base resin is 40 molt or less, and the blowing agent component having a boiling point of 40° C. or higher is 40 molt or less is uniformly mixed and extruded into foam. A method for producing a closed-cell vinyl chloride resin foam.

Claims (1)

[Claims] A base resin consisting of 85 to 30% by weight of vinyl chloride resin and 15 to 70% by weight of styrene resin and/or acrylic resin; It is a mixture of one or more components selected from logenated hydrocarbons, has a molar average molecular weight of 120 or less, a molar solubility coefficient (8P value) of 7.6 or more, and has a gas permeation rate through the base resin of air. A vinyl chloride resin closed cell foam characterized by homogeneously mixing and extruding a foaming agent having a faster blowing agent component of 40 molti or less and a blowing agent component having a boiling point of 40° C. or higher of 40 molti or less. Production method.