DE2147321A1 - Thermoplastic, heat-sealable, composite material, thus made from armored fiber material and processes for their production - Google Patents

Description

DR.-ING. RICHARD GLAWE ■ DIPL-ING. KLAUS DELFS DIPL-PHYS. DR. WALTER MOLL

MÖNCHEN HAMBURG MUNICH

8 MDNCHEN 26 POST BOX 37 LIEBHERRSTR. 20th TEL (0811) 22 6548

2 HAMBURG 52 WALTZSTR. 12 TEL (0411) 89 22 55

YOUR SIGN

REGARDS:

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MONKS

A 61

THE DEXTEE 0 ORPORATΙ0ΪΓ Windsor Locks, Connecticut / USA

Thermoplastic, heat-sealable, composite material, as well as pas- ter fabric equipped with it Process for their manufacture

The invention relates to a thermoplastic, heat-sealable material for producing heat-sealing properties in a paper-like produced in water (waterlaid), in particular unsized, web-shaped fiber material. One such Fiber material is used below for the sake of simplicity referred to as paper or paper material, which is not

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is to be understood as paper in the narrower sense. The invention further relates to a heat-sealable web material suitable for infusion purposes, in particular paper material, which contains the thermoplastic, heat-sealable material of the invention, and methods for making the thermoplastic material and the pulp equipped with it .

It is known that fibrous paper material is suitable for use as a packaging material for infusion purposes in the manufacture of tea infusion bags and the like. For many years, a number of attempts have been made to impart heat-sealable properties to paper material of the type described above, which enables the infusion bag to be heat-sealed at its edges, while at the same time preventing the infusion properties of the paper from being affected or impaired. When used for tea bags or the like, it is necessary to achieve an effective seal which is stable for a considerably longer period of time when immersed in hot or boiling water. Originally this was achieved by spreading a granulated or powdered, thermoplastic, heat-sealable mass on a surface of a previously formed, porous paper material and partially melting the granulated material, whereby it adhered to the paper without destroying its porous structure. The commonly used thermoplastic resin consisted of a vinyl chloride

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Vinyl acetate copolymers which are easily accessible in powdered form is. Unfortunately, the resin was not available as a fine powder and did not result in just one powder for the paper exceptionally rough surface texture, rather also to unaesthetic looking, translucent stains distributed on the paper. At the

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initial heating of the copolymer to achieve a "Better adhesion of the resin to the fibrous paper structure also shrunk the resin, making it undesirable agglomerated or clumped ("balling). Furthermore tended the molten resin to the liquid infusion rate by belittling the paper. Finally, problems arose in that the resin adhered to the The sealing machine's welding jaws. Although the copolymer is also made by discontinuous application of rollers "or similar measures that could be applied to the preformed paper were materials treated in this way never particularly successful commercially.

In US Pat. No. 2,414,833, a highly porous paper material made in water is described, which the heat-sealing vinyl resin in fiber form is added. The thermoplastic fibers are at least about 1.6 mm long and are mechanically entangled with the cellulose fibers during papermaking. This allows an extent of the controlled amount of terms in the tissue that cannot be achieved with the powder used up to now. The heat-sealing fibers can be distributed in the fabric, however, are preferably arranged mainly on one surface of the paper material.

Although the oopolyaeran used in the paper materials Vinyl resins according to the corresponding FDA guidelines

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were approved, tea testers could always find small traces of material in the tea used to prepare the leeward hot or boiling water is given off by the resin. As a result of this recognizable and taste-impairing Properties one looked for improved sealing methods and also for other thermoplastic materials for use as a heat sealable component in such paper materials.

In this context, some improvements compared to copolymer powder-coated paper have been achieved by the copolymer has been replaced by polyethylene and similar thermoplastic polyolefin powders, which have the undesirable taste-impairing properties Properties no longer exhibited. Some of the polyethylene has a specific density less than 1, it is generally applied to preformed paper in powder form or as a uniform thin layer or foil, which is subsequently destroyed by heat shrinkage. Unfortunately, paper treated with polyethylene powder in this way exhibits many of the same disadvantages as they do previously occurred on powder-coated materials. For example, the powder does not stay on one side of the paper be liable. In addition, it is difficult to melt the powdered polyethylene in a suitable V / iron on the paper without At the same time, degradation phenomena occur in the paper material due to the action of heat.

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With the help of both methods described so far, i.e. with powder or films that are subsequently destroyed, it is not possible to anchor polyethylene in the paper itself in the advantageous manner as described in US Pat. No. 2,414 known wet paper production is possible. Try polyethylene powder to the wet end of a paper machine, so in a similar way to v / ie in the aforementioned US patent described, encountered numerous difficulties, most notably the flotation of the material due to its low speci- ' fishing density.

The aim of the invention is to provide a porous, heat-sealable, suitable for infusion purposes, in particular paper-like fibrous web material without the Uaehteile described above, but with the advantages of the fibrous and powdery heat-sealable materials are retained. At the same time, an improved seal strength with a lower Demand for heat-sealable material can be achieved.

The heat sealable fibrous infusion paper material of the invention is suitable for use in tea infusion bags and the like. suitable. The sheet material shows improved heat seal strength, if it is in a wet paper production process from fibers for paper production and fiberless, water-dispersible, composite, heat-sealable particles will. The particles are heterogeneous and can themselves

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do not form a self-supporting web separated from water. The particles contain at least about 25 $> or more of a granulated polyolefin very delicate in one, fibrillins network of a carrier resin, for example of a thermoplastic vinyl copolymer, is finely dispersed and embedded. The composite particles are attenuated as they are formed by dynamic flow precipitation of the carrier resin from its solution in which the granulated polyolefin is dispersed and are given an irregular shape.

The heat-sealable infusion paper material is particularly advantageous in that it contains heat-sealable particles which have the beneficial properties of powdered heat-sealable Have materials that can be incorporated into the paper and retained in it. Bas paper material according to the invention exhibits a uniform, heat-sealable surface, in particular no longer a has disadvantageous roughness or translucent stains, which is a disadvantage of powdery vinyl copolymers containing Paper material is.

Another advantage of the heat-sealable paper web material according to the invention is an improved heat-seal strength, greater resistance to delamination in hot or boiling water as well

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"Better chopping properties, with smaller ones Quantities of heat-sealable particles and no deterioration in the dry-seal properties occurs.

To achieve the object described above, the invention also provides heterogeneous, composite, heat-sealable Particles of attenuated, non-granular structure are proposed for use in fibrous infusion paper materials are suitable. A particularly advantageous property of the particles is that they are with the Pasern des Paper material can be anchored and thereby form a firm, mechanical bond with them, while at the same time the benefits of granulated, heat-sealable materials remain.

The invention thus creates in an advantageous manner in water-dispersible, composite, heat-sealable particles with very fine, thin, refined (attenuated), irregular, knotty, chain-like appearance, which are particularly good for use as a heat-sealable component of unsized, fibrous Infusion paper material are suitable. With particular advantage a composite particle is used for this purpose, which consists of a pesticide dispersion of thermoplastic granules, which in an irregular, network-like arrangement of stretched, fine, fiber-free, but fibrillin-shaped strands of another, preferably immiscible or inert (inooapatible ),

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.Thermoplastic carrier material finely divided and embedded

A heterogeneous, composite one is also particularly advantageous Particles according to the invention, consisting of physically unchanged, granulated, heat-sealable Material that can be incorporated into a fibrous paper material in the front end of a paper machine. The paper material thereby obtains heat-sealable properties and an improved sealing strength, whereby granulated material of enclosed in a fine grid of thermoplastic carrier strands and is held.

According to the invention, a composite, heat-sealable component containing a granular component is particularly advantageous Particle that can be introduced into a wet process for making paper. The particles according to the invention show no auto-adhesive properties at room temperature or below temperatures such as those for heat sealing required are. The particles still show no contraction or shrinkage properties when heated, whereby agglomeration is avoided and the paper material, in which the particles are embedded, at the same time receives a smooth surface.

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A method according to the invention for producing paper for incorporation is also particularly advantageous of powdered thermoplastic Grantilen lower Dense into a fibrous paper on the wet end of a paper machine. The method according to the invention enables uniform distribution and mixing of the powder in the

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fibrous paper and extremely good adhesion Entanglement or mechanical entanglement. Furthermore, a wet process for the production of paper is provided, whereby a thermoplastic powder with a specific gravity of less than 1.0 in the aqueous phase at the same time Compensation for the tendency of the powder to float on the surface can be distributed in the aqueous phase.

Another advantageous feature of the invention is from a process for the production of heterogeneous, compound diseases, consisting of intertwined in one or granules entrapped on fibrous carriers. The process further comprises optimal and controlled process conditions and parameters for the production of in one Hate processes for making paper useful particles are most suitable.

Another advantageous feature of the invention consists in the provision of a method for making composite thermoplastic particles of the foregoing described type and its subsequent incorporation in an unsized, fibrous paper in the wet end of a Paper machine, although one component of the composite particles retains individual granular properties. to this feature of the invention also includes the creation a process whereby resinous, heat-sealing parts

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produced by which the accumulation of resin occurs Heat-sealing baking is minimized or significantly reduced if one containing the lamps Paper is used for the production of infusion packs, e.g. tea infusion bags or the like.

It is also particularly advantageous to achieve the advantages described above in a simple and economical manner Way preferably using materials that are approved under the appropriate FDA guidelines. These advantages in particular are that the heat sealable infusion paper materials of the invention have improved taste properties and have a more favorable appearance and excellent heat seal strengths, approximating to a third of the previously required heat sealing material is saved.

Further advantages of the invention emerge from the context or are described below.

The invention is illustrated below with the aid of the figures described in more detail with reference to some preferred embodiments.

The enclosed figures show:

Pig. 1 is a flow sheet of an advantageous process for making the composite heat sealable particles

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/ 3

and the infusion paper material according to the invention;

Pig. Figure 2 is an enlargement (38 times) of the composite heat sealable particles of the invention;

. 3 another enlargement (60 times) from after Heat sealable particles made by the method of the invention. The granulated component embedded in the carrier component is clearly recognizable in the Pigur.

In Pig. 1, a process for the production of the composite, heat-sealable particles and the infusion paper material is shown schematically in the form of a plow pattern. As can be seen from the flow chart, the elongated, attenuated, composite, heat-sealable particles are made from two different thermoplastic materials by a technique that involves simultaneous precipitation and stretching. The composite particles are formed in the form of fluffy precipitates and are characterized by the presence of elongated, non-granulated strands which can be anchored to conventional papermaking fibers during the formation of the paper web, thereby producing the desired heat-sealable infusion paper. The composite particles are no web forming parsers are and can not itself a stable, ungeleimtee paper, which consists of 100 i "from the particles which form. Correspondingly, the particles have to be made of different types of paper for papermaking

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can be combined to give the desired stable, fibrous paper structure.

As can also be seen from the flow diagram, the carrier resin is dissolved in a solvent suitable for this component and the insoluble, granulated resin component is then dispersed in the carrier resin solution. A precipitant for the carrier resin is subjected to suitable flow properties to produce the desired attenuation, for example by rapid agitation, stirring or other seer conditions or, simply, by rapid flow through a tubular precipitation chamber. The resin dispersion is added to the precipitating agent under these conditions. When the carrier resin precipitates out of solution, it picks up the in Pig. 2 shown elongated, fibrillin-shaped structure, which carries the undissolved, thermoplastic, granulated component anchored in it. The granulated resin component is embedded and enclosed in the carrier resin and held in the matrix from the stretched, fibrous precipitate. According to a feature of the invention, the granules are not physically changed during the entire process of precipitation , but are firmly anchored in the carrier resin. The actual appearance of the heat sealing particles can best be seen from Tig. 3. As can be seen, discrete granules of undissolved resin are arranged everywhere in the carrier resin matrix at random distances from one another. As you continue to see from Tig. 3 results,

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if the carrier resin is not in the form of strands of the same shape and size. On the contrary, the support matrix varies widely in terms of its torrn and size and appears to consist of a multiplicity of fibrillin-like strands which arbitrarily extend into and out of the main structure. Due to the random dispersion of the granulated component, some of the carrier resin strands embed the granulated thermoplastic resin, while others are completely free of any granulated particles. This to a large extent the laws of chance subjected fibrillins structure has the result that the heat-sealing particles are extremely retained well during the manufacture of paper, although more than 20 i "of the particles have a maximum diameter of less than 0.4 mm and even not in are capable of forming a stable, unsized paper in the absence of other papermaking fibers. The particles can easily be dispersed in water and fed to the end of a paper machine in much the same way as conventional papermaking fibers. Preferably, however, the particles are delivered so that a two-layer, heat-sealable infusion paper material is formed. It can be assumed that the particles are filtered from their aqueous dispersion medium by the initial deposition of papermaking fibers before the complete paper material has formed or the paper is completely dewatered. The particles are preferably arranged at the level of a surface of the paper and

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thus give it the desired heat-sealing properties. It is of "particular advantage that the after Invention produced heat-sealing particles have particularly favorable properties. They show for example largely no shrinkage when heated in the conventional paper drying system, little or no tendency to Agglomeration or auto-adhesion as well as resistance to adverse penetration of the paper material in the case of heat-sealing ones Temperatures. The granulated. Resin component makes about a quarter and more, preferably about half the total weight of the particles. The properties of the granulated, thermoplastic materials are thus made clearly noticeable in the finished paper material during heat sealing.

The normally solid, synthetic, thermoplastic resins used as the starting material are not only different in terms of their composition, but. also generally show some degree of intolerance. In particular, the thermoplastic material used as the granular component of the composite particles must be in be insoluble in a solution of the carrier resin. In other words, the solvent must be able to dissolve the carrier resin, however, the granulated resin remains relatively unaffected, i.e., undissolved. The carrier resin component must also can easily be precipitated from the solvent under the required conditions, so that the desired process

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attenuation of the particles is obtained.

The flow sheet contains examples of granulate and carrier components, with which excellent results are achieved. However, the specified materials are only for Explanation and do not represent a restriction within the meaning of the invention. The vinyl copolymer preferably used The carrier resin consists of a copolymer of vinyl acetate and vinyl chloride. The thermoplastic vinyl copolymer is in. Acetone is readily soluble and can be extracted from its solution by adding it to a suitable precipitating agent, e.g. water or water-acetone, easily precipitated. The individual.1 used Polymers are according to the appropriate FDA guidelines approved. In particular, polymers are used which are suitable in terms of their heat-sealing properties. In general, solid, fully synthetic, fiber-forming, thermoplastic resins are used insofar as they form pairs or groups that result in the formation of the desired allow composite, granular-fibrous structure of the heat-sealing particles obtained. ! Therefore also can other resins depending on their further use such as polyamides or various nylon resins, polyvinyl compositions and copolymers, polyolefin compositions including polyethylene, polypropylene as well as copolymers and polyesters.

In order to explain the invention in more detail, the following is described

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based on the vinyl copolymers approved according to the relevant IFDA guidelines for use in tea infusion bags or the like. Accordingly, a preferred granulated resin component is comprised of a polyolefin composition of the polyethylene type and the carrier resin is comprised of a copolymer comprised of about 86 # vinyl chloride and 14 $ vinyl acetate. It should be emphasized that a particular form of the carrier resin used as the starting material is irrelevant because the carrier resin is dissolved during the process according to P of the invention.

It should also be emphasized that the solvents and precipitating agents used in each case depend on can change the resins used. In the preferred embodiment of the invention, that is used Solvent from acetone, not only because of its solubility properties, but also as a result of its adaptability to the precipitation process, whereby the carrier resin simply by adding to water or a water-acetone

Mixture can be precipitated.

The granulated resin component remains during particle formation Precipitation process unchanged. Size, design and properties of the granulated resin component can eomit according to the further use of the end product. products to be selected. It preferably consists of one fine powder of a thermoplastic synthetic resin,

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wherein a major portion of the granules are of particle size

has which is substantially less than 75 yx. At least 40 liters of the material should pass through a 325 mesh screen. The size distribution of the particles varies between approximately 10 μ and approximately 100 μ, the material preferably used being in the lower half of this range. One material of the type described above which has been used with good results is a polyolefin powder manufactured as "Super Dylan 7120 (J-1)" by the Koppere Chemical Company of Pittsburgh, Pennsylvania, which is believed to be an ethylene butylene copolymer. The material shows a specific density of 0.96 at 23 ⁰ C (ASTM D-1505-63T), a melt index of 12.0 (ASTM D-1238-62T) and a softening temperature of 126.7 ° C (ASTM D- 1525-56T). The shape of the material is relatively uniformly spherical to spheroidal. The material shows a non-linear or arbitrary molecular chain orientation. I at least 85 "of the powder through a 100 mesh screen, more ale j £ 80 through a 200-mesh sieve and more than 40 # through a 325-mesh screen. The ratio of granulated component to carrier resin component can vary considerably, although a ratio is generally preferred, the amount of the granulated component being greater than 20% by weight of the composite heat-sealing particles obtained, particularly when the particles are used for the manufacture of heat-sealable infusion paper materials Use of tea infusion bags and the like are to be used. In Table I is the effect on the .

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to

Heat sealing properties of the obtained infusaon paper shown as a function of various ratios of granulated component to carrier resin component.

Table I.

Properties of an infusion paper * with different particle compositions

Test ratio polyethylene 8 vinyl copolymer

10x70 20:80 25:75 55:45

Cushioning (sec.) 65 210 600+ 600+ Dryrock delamination 260 305 260 (g / in)

* Two-ply paper. All paper stocks contain about 30 weight percent heat sealable particles.

As can be seen from Table I, there is a marked increase in the heat sealing properties of the infusion paper as the concentration of the granulated component increases from 20 % to 25 % and above. These improved properties are obtained without adversely affecting other properties of the paper material.

Certain upper limits on the proportion of granulated

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Resin components in the composite heat-sealing particles can also be drawn. In wet papermaking processes, heat seal particles having a specific gravity less than 1.0 are undesirable. Similarly, when a polyethylene powder having a density of 0.96 is used as the granular component of the particles and the vinyl copolymer carrier resin has a density of about 1.36, the upper limit for the granular component is about $ 85. Above this percentage, the composite heat-sealing particles have a specific gravity that is close to or less than 1.0. The parts then tend to swim on the surface accordingly. In reality, a maximum proportion of approximately 70 - 75 i »is used in practice. The maximum level is also preferable because the physical uniformity of the heat-sealing particles between 70-75 ° and 85 ° is very poor and can be broken very easily even with the low degree of agitation that occurs during papermaking. The destruction of the heat-sealing particles leads to the breakout of essentially free polyethylene granules, which results in flotation and foam stabilization problems in the paper machine. In addition, the high percentage of granulated component during drying leads to poor adhesion to the conventional paeern of the infusion paper, resulting in an infusion paper material that has a low dry seal

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having strength.

At the same time it must be pointed out that the economy of the precipitation process speaks in favor of a large proportion of granular components, because it increases them Sealing particle to solvent ratios in the primary dispersion and higher output rates can be achieved. In addition, larger proportions of the granulated component result in smaller amounts of self-adhesion during removal of the precipitation of sealing particles and advantageously to a smaller particle size of the obtained heat sealing particles.

On the other hand, small proportions of the granular component have advantages in papermaking. Namely, heat-sealing particles with greater stability during papermaking, which are easily dispersible, so that little or no difficulties arise due to floating material, are obtained. However, as can be seen from the results summarized in Table I values results in a deterioration of the heat-sealing strength of the heat-sealing particle, when the amount of granular component is less than 25 $>. The binder obtained also tends to self-adhesion below this limit and has a coarser or larger fiber structure, whereby the limits of the desired particle size described below are

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size are significantly exceeded. After another Feature of the present invention is the optimal ratio of granulated to carrier resin component between T: 3 to 3: 1. Within this relationship there will be a A system that incorporates the advantageous features of both the process for making the heat-sealing particles and the wet process for papermaking. It goes without saying that the exact proportions of the components can change, depending on the situation of the raw materials used in each case, the economic viability of the precipitation process used in each case, the papermaking system using the heat-sealing particles and the requirements that are placed on the infusion paper to be produced. The above However, conditions were found to produce infusion type paper materials for tea infusion bags and the like. as best suited.

The composite heat sealable particles of the invention are made by adding the thermoplastic dispersion to one _percent precipitant for the carrier resin under suitable agitation conditions. In the precipitation process, the dissolved, synthetic, polymeric material is subjected to strong seer conditions at the same time as the precipitation. The process causes the precipitation to tear apart and stretch and leads to attenuated, heterogeneously composed precipitation particles. The one in the

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Carrier solution, which remains physically unchanged, dispersed, granulated component is refined during the (attenuated) Precipitation firmly embedded or planted in the carrier resin, whereby its granular properties are retained. Although the simultaneous shear precipitation technique is similar to that used in the cellulose acetate industry and used in the manufacture of fiber-like materials (fibrids), the composite, heat-sealable Particles according to the invention do not have any particular essential properties of a fiber-like material (fibrids). In particular, the particles according to the invention neither form a paper structure that is stable to moisture (wet strength integrity), nor are they actually fibrous in shape. You are not able to create a stable, unsized one on your own Form paper. More precisely, paper webs that consist only of these particles cannot be made by one paper web-forming screen are removed and after drying in the air show little or no stability.

It goes without saying that the type and intensity of the movement during the precipitation of the heat-sealable particles can be varied, because the formation of a fiber-like structure (fibrid formation) is not required. However, the attenuating forces must be great enough to give the precipitating resin an elongated, fibrillin- like shape or property, thereby making it used in a process for making paper and in the paper making process.

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■ material can be anchored by conventional paper fibers can. It is believed that the absence of shrinkage of the composite particles upon heating in is due to the unoriented character of the carrier resin, which forms during the precipitation process.

The concentration of the carrier resin in its solution before precipitation can be varied within certain limits. However, it is generally kept below 35 wt. - <$> . The actual working range is about 10-30% by weight, with the preferred range for the vinyl copolymer in acetone being about 17-20% by weight.

According to the invention, certain temperature and concentration conditions of the precipitation solution are necessary to achieve optimal results. In the illustrative preferred embodiment in which the carrier resin is dissolved in an acetone solution, a precipitating agent containing a mixture of acetone and water can be used provided that the precipitating solution is less than about 50 % acetone and has a temperature which is below room temperature, ie below about 25 ⁰ O is. If either or both of these interrelated conditions are varied, the resulting composite particle will be affected. An acetone concentration in the precipitation solution of less than about $ 25> leads, for example, to economically poor results in the insulation

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system. The preferred working concentration for the precipitation liquid is therefore between 25 and 50 µL acetone, with a typical concentration being about 38 µL.

As already stated, temperatures of more than 25 ^° C. are undesirable. When operating for example at a temperature of 3O ⁰ C, the particles obtained adhesive properties tend to agglomerate and form particles of undesirable size, in particular when working on granular components at low concentrations. The temperature of the precipitating agent is preferably in the range between 0 and 5 C. These temperatures cause good dispersion of the precipitate and facilitate the filtration of the resulting composite particles. The precipitating agent preferably used is, accordingly, to about 38 # of acetone and is kept ⁰ C at a temperature of about O. Under these conditions, the composite heat-sealable particles remain dispersed and show no undesirable self-adhesion.

As mentioned above, the size of the composite, heat-sealing particles depend on numerous factors. The particle size should generally be appropriate for the papermaking process and for the ability of the paper machines to work with dispersions of the particles. In general, large particles provide poor dispersions in the papermaking system and have poor entanglement

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and adhesive properties to the paper fibers during the conventional Paper drying process. Big, coarse! additionally result in a relatively rough surface, tend to flatten out (coining effect) during processing and lead to detrimental, translucent stains in the sealant s area of the infusion paper. Small particles result naturally good dispersions during the papermaking process and have excellent felting and adhesive properties compared to the paper during the drying process. The particle size increases with increasing shear forces during the precipitation. The shear force can of course vary with the speed of movement of the precipitant and its Change viscosity. The period in which the precipitate is highly plastic and deformable influences the Size of the resulting heat-sealing particles. By extending the precipitation time, for example when using a precipitant that contains large amounts of the polymer solvent contains, the shear forces have more opportunities to break the structure, creating a heat-sealing particle with a smaller size. Very small particles, for example on the order of polyethylene powder, are undesirable, because they run counter to the purpose of the invention.

The particles are expediently according to the Bauer-McNett scale classified. The separation is carried out on an aqueous particle dispersion and is given in percent by weight, which is obtained with sieves of different sizes. in the

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In general, particles retained on an H-mesh screen are undesirable for use "in the manufacture of heat sealable infusion paper materials for the reasons described above", but about 1% of the particles are acceptable. Particles retained by a 35 mesh screen are also disadvantageous, but to a lesser extent; up to $ 10-15 is affordable. The precipitation conditions must accordingly be chosen so that essentially no particles are formed which are retained by a 14-mesh sieve and that at most about 10 i » 35-mesh particles are formed. For the remaining 90 # particles, a normal size distribution is preferred, with the mean size distribution roughly corresponding to that of a 150 Meeh sieve. A pair of examples of heat-sealing particle size distributions which give excellent results are given in Table II.

Table II

Size distribution * of the composite particles

Sieve
Ue sh Sieve size
(mm) held back
Particle (¥>) B. A. 0.3 14th 1.17 0.2 10.7 35 0.42 1.3 56.2 150 0.10 35.S. 35.8 Pan 62.7 * Bauer-McNett scale
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It goes without saying that the particle size obtained in the shear precipitation when used in the paper industry conventional grinding devices is reduced, for example by the pulp separator according to Jordan. Indeed the strong, hydraulic shear forces, as they occur in a machine of this type, prove to be advantageous versus metal-to-metal contact, as in others common grinding devices, for example in Dutch occurs. Table III gives in this context the influence of particle size on the properties of the heat sealable made from these materials Infusion paper again.

Table III

Influence of the size of the sealing particles on the properties of the infusion paper *

Particle size

retained by 35 mesh sieve

passed through 35 mesh sieve and retained from 150 MeBh sieve

Vapor resistance
(sec.) 400 600+ Dry delamination
(G) 210 210 Seal penetration
(in.g / in2) 195 2

The sealing particles are made of polyethylene-vinyl copolymer in the (Judgment ratio of 55 »45 · Classification according to the Bauer-MoNett scale. It became two-ply papers using a paper with a cream weight of

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nominally 4.54 kg, of which about 1.36 kg sealing Particles passed, produced.

As can be seen from Table III, the particles retained by a 35 mesh screen are not as good Heat sealing properties such as particles that are small enough are large enough to go through a 35-MeSh-SiOl) to be retained by a 150 mesh screen. The results for seal penetration are particularly important. In these experiments, large values mean that the thermoplastic, sealing resin penetrates the fibrous paper structure to a large extent. A penetration of this kind causes resin to build up on the heat seal jaws a sealing machine. Saraus follows that one large percentage of particles retained on a 35 mesh screen is undesirable. This effect makes is even more noticeable on material retained by a 14-mesh screen.

Although the lower limit of the particle size can be varied, it should nevertheless be ensured that the particles are large enough must be so that they are retained by the fibrous base during the manufacture of the infusion paper can be. The particle sizes given above relate to the manufacture of infusion paper for use bti coffee and tea products. Ea, however, are other areas of application where the presence of larger particles Bioh does not have a negative effect.

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To better assess the shape of the heterogeneously composed Particle is shown on Fig. 2 and Pig. 3, in which typical particles according to the invention are depicted are. In Pig. 2 the attenuated, fibrillin-shaped property of the flaky precipitate can be clearly seen. Pig. 5, on the other hand, shows the chain-like, knotty strands that are characteristic of the composite particles are. The shapes of individual particles change considerably and randomly; their elongated, non-granulated character is also clearly visible. The composite, heat-sealable particles become ordinary after precipitation filtered and washed thoroughly before being reused for further use in the wet end of a paper machine Water can be dispersed.

As stated earlier, the heat sealable infusion paper material is prepared according to the invention by a dilute dispersion of heat-sealable fibers from a Vinyl copolymer and with a length of at least 1.59 mm is given to an entry of non-thermoplastic fibers for papermaking when the fibers are on the papermaking Sieve to be deposited. The vinyl copolymer fibers are preferably placed in the feed hopper Given paper machine. They are then placed on the paper forming screen at a central point along the course of the. Separated sieves for fiber collection.

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The paper machine is operated in essentially a conventional manner arranged. The liquor ratio of the composite particle dispersion according to the invention corresponds approximately to the previously used liquor ratios. The dispersion is added to the paper fiber input in such a way that mixing the particles and fibers as well as their deposition on the paper-forming wire in the paper machine takes place. As already stated, the non-thermoplastic fibers for papermaking are generally initially on the paper-forming sieve deposited, namely at a point which is in the direction of feed before that point at which the heat-sealable Particles are abandoned. In this way will a first phase or first fiber layer on the paper forming end The machine's sieve is formed so that one surface of the resulting infusion paper material is made entirely of non-thermoplastic Paper-making fibers. The first layer of paper material thus acts as a base for picking up and anchoring the composite particles. The fibers then continue to separate together with the particles if that paper-forming sieve is moved through the feed container, which supports the separation and retention of the particles will. Although some papermaking fibers may be present on the top surface of the resulting paper, there is it consists mainly of the composite, heat-sealable particles. It follows that the concentration of the compound Particle decreases in the depth of the paper sheet. The first deposit of fibers acts as both

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Filter bed for the particles and as a base for receiving more laser. It should be noted, however, that even the first deposited fiber layer is extremely thinned and also later participates in the dynamics of the system, whereby it easily becomes matted with later deposited fibers. Although between If there is no sharp dividing line between the two layers of paper material, the lower surface of the paper material is essentially free of thermoplastic particles. This is particularly advantageous when the paper material to be used in heat sealing packaging machines. Such machines usually have heated, under Pressure working jaws on. It is important that the thermoplastic material does not come into contact with the hot jaws prevents resin build-up on the jaws and damage to the seal.

According to a further advantageous feature of the invention, considerably less thermoplastic material is required to achieve the same and even improved heat sealing properties. The heat-sealing properties that were previously achievable with a certain amount of material can now also be achieved if only two thirds of the previously required heat-sealing composition are used. For example, if an infusion paper is made with a content of about 3.175 kg per ream (480 sheets, 60.96 χ 91.44 cm) of non-thermoplastic fibers, only about 0.91 kg per egg of composite, heat-sealed

5 2098U / U92

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Sealing glow is required to have sealing properties to achieve, for which 1.36 kg of vinyl copolymer fibers per egg were previously required.

In view of the fact that the composition of heat-sealing particles in the absence of fibers for papermaking cannot form stable, unsized paper, the use of the two-layer structure is in general preferable. However, it is also possible to completely mix the particles with the paper-making fibers and the Then use the mixture, provided that the particles are sufficiently retained in the paper structure and not out of it washed out during papermaking. When the composition is made up of heat-sealing particles and fibers for When papermaking is thoroughly mixed, it is desirable to have the thermoplastic particle composition firmly in the paper to bind finely ground cellulose fibers. Other conventional binders can also be used successfully.

The infusion paper material obtained in papermaking has a thin, porous and light structure, but is of sufficient stability to be used during manufacture Not to be destroyed by tea infusion bags and the like. Paper materials of the type described above generally have a base weight of about 408 to 7126 kg per ream and are easy to process in the heat-sealing packaging machines

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we

In the following the invention is based on exemplary embodiments explained. The quantities used relate to weight.

Example I.

A carrier resin solution is prepared by dissolving 45 parts by weight of a vinyl copolymer resin (14 # vinyl acetate and 86 $ vinyl chloride) sold under the designation ¹¹ VYHH "by Union Carbide Corporation in acetone parts by weight of polyethylene powder (Super Dylan 7120 (J-1) polyethylene powder) was added with a specific gravity of 0.96. the resulting dispersion was mixed to prepare a dispersion of the polyethylene powder to obtain the carrier resin solution. the solution was stirred at a temperature of about 29 ⁰ C held.

A precipitation solution was prepared from about 38% acetone and 62 % water and cooled to ^{0 ° C.}

In a Uiederschlagsrohr constant flow are composed of the above-described solutions, heißversiegelnde particles, consisting of approximately 55 i »polyethylene and 45 i> vinyl copolymer. The precipitation solution is passed through a central, tubular part at a rate of about 5 »5 g / min and the resin

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suspension is made at a rate of 0.4 g / min to the precipitating solution flowing through a hole that is at the. Side of the tube is given. The composite fibrous particles thus obtained are filtered with Washed with water and redispersed for further use in the papermaking process.

The dispersion of heat-sealing parts is made by a pulp separator passed to Jordan and brought into the feed container of a paper machine, with the feed speed is sufficient to give a finished paper having a 20% by weight heat-sealing particles. The resulting infusion paper material is excellent in appearance, has good heat and hate seal strength on, is tasteless and in all other properties with conventional, heat-sealable infusion paper materials comparable. The paper obtained is used for further processing into tea infusion bags on the usual Pormund Sealing machines used. The tea infusion bags so produced have excellent heat and wet sealing properties on.

Example II

The procedure according to Example I is repeated, a polypropylene powder being used in place of the polyethylene powder. The obtained he ISS sealed particles are used to produce a two-layer, heat-sealable Germany

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2Ϊ47321

fusion paper with a total concentration of thermoplastics Light of about $ 30 of the total paper weight is used. The resulting paper, like the paper material in Example I, has excellent properties.

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Claims (19)

Claims 1. Thermoplastic, heat-sealable material for the heat-sealable finishing of web-like fiber material produced in water (waterlaid), thereby gekening. It is suggested that the heat-sealable material which can be incorporated into the paper material in the wet end of a paper machine consists of composite, heterogeneous lamps which in turn contain at least about 25 wt. another, opposite the first inert (incompatible) or immiscible thermoplastic resin in finely divided form and is firmly embedded, wherein the heterogeneous particles not capable of forming water-self-supporting from V / ater remote web and its size distribution is such that at least 90 i "of Pass particles through a 35-mesh sieve. 2. A thermoplastic, heat-sealable material according to claim 1, characterized in that the granular component is a polyolefin, from which the particles bie consist of approximately 75 i ", wherein the powder to form a chain-like, nodular arrangement of the particles combined with the carrier matrix. 2098U / U92 - 36 - 3. Thermoplastic, heat-sealable material according to claim 1, characterized in that the Carrier matrix essentially made of a vinyl chloride-vinyl acetate copolymer consists. 4. Thermoplastic, heat-sealable material according to claim 1, characterized in that the granular component forms $ 25 to $ 75> of the composite particles and contains a polyolefin powder which has a specific density of less than 1.0, a melt index of about 12, 0 and has a substantially uniform, spherical structure, and a particle size distribution in which more than 80 # of the particles pass through a 200-mesh sieve and more than 40 microns through a 325-mesh sieve. 5. Thermoplastic, heat-sealable material according to claim 1, characterized in that the composite particles have an average size of about 100 μ and about 55 wt. JG thermoplastic polyolefin granules made of polyethylene or polypropylene polymers or copolymers with a specific density of less as 1.0 and about 45 wt. Jt of stretched vinyl copolymer in a refined (attenuated), fibrillin-shaped arrangement, the vinyl copolymer connecting and holding the polyolefin granules in a chain-like manner. 209814/1492 ΫΟ 2Η7321 6. Thermoplastic, heat-sealable material according to claim 1 to 5, characterized in that it is dispersible in "water and the resin granules have a specific gravity less than 1.0, the Ratio of granulated resin component to carrier matrix is chosen so that the composite particles one have a specific gravity greater than 1.0. 7. Thermoplastic, heat-sealable material according to claim 1 to 6, characterized in that i without t the granulated resin component is made of a polyolefin and the carrier resin component is made of a vinyl resin. 8. In V / water deposited, heat-sealable web material made of papermaking fibers suitable for infusion purposes, characterized in that it contains composite, thermoplastic, heat-sealable particles according to claims 1 to 7 and in that the composite particles are mixed with the fibers and anchored in the web material, the particles themselves being unable to form a self-supporting, Y / water separated web and having a particle size distribution in which about 90 % of the particles pass through a 35-mesh sieve, and the particles consist of individual, granulated components which are refined in a refined form (attenuated) carrier resin matrix are finely distributed and embedded. 2098U / 1492 - 38 - 2H7321 9. Web material according to claim 8, characterized in that the heat-sealable particles to are concentrated on a surface of the paper material, their concentration decreases toward the inside of the paper, and the opposite surface of the paper consists essentially of papermaking fibers. 10. sheet material according to Atis claim 8, characterized in that the granulated component of the composite Particle has a specific gravity less than 1.0 and during paper formation with the paper is anchored. 11. Web material according to claim 8, characterized in that the granulated component is a thermoplastic Contains polyolefin powder and the carrier matrix consists of a thermoplastic, compared to the granulated component inert (incompatible) resin, with the heat-sealable particles mainly near a surface of the paper are arranged. 12. Web material according to claim 8, characterized in that the granulated component makes up 25 to 75 Grev /.- ji of the composite particles and the carrier matrix consists of a thermoplastic resin which consists mainly of a vinyl acetate-vinyl chloride copolymer . 2098U / U92 - 39 - 2H7321 13. Water-immersed, infusion-suitable sheet material made of fibers for the manufacture of paper and composite, water-dispersible, heat-sealable particles, thereby denoted that the composite Light are mixed with the fibers and anchored in the paper material, with the composite particles have a specific density greater than 1.0 and cannot form a self-supporting web separated from water, and that the particles are individual, granulated components ", with the granulated components being a smaller one have a specific density of 1.0 and are heterogeneously dispersed and embedded in a refined (attenuated) carrier resin matrix are. 14. Web material according to claim 13 »characterized in that the granulated resin component a polyolefin and the carrier resin component consists of a yinyl resin. 15. A process for the manufacture of a heat-sealable paper material for infusion purposes for use in tea infusion bags and the like, characterized in that dispersions of fibers for papermaking and heat-sealable Material are produced and a paper material is formed therefrom, wherein the dispersion of the heat-sealable Material by dispersing an insoluble, granulated resin component in a solution of a carrier resin 2098U / U92. - 40 - 2U7321 component produced and the carrier resin component under Shear is precipitated in the presence of the granulated component, resulting in composite, heterogeneous particles, which, due to their size and properties, do not form a self-supporting paper made of Yfasser which is self-supporting in water enables bind, and the particles consist of a fibrillin-shaped matrix of the carrier resin component in which the granulated Component is fully dispersed and embedded. 16. The method according to claim 15, characterized in that the carrier ^{component is precipitated by adding the dispersion to a precipitating agent, the precipitating agent having a temperature of less than 25 0} O and shear flow conditions for refining (attenuation) of the precipitate are simultaneously with its formation « 17. The method according to claim 15, characterized in that the composite, heterogeneous particles Polyolefin granules with a lower specific density than 1.0 in an amount insufficient to cause flotation of the particulate composition. 18. The method according to claim 15, characterized in that g e k e η η ze It is believed that the granulated component has a specific gravity less than 1.0 and in a solution the carrier component is dispersed in an amount that 2098U / 1A92 - 41 - 2U7321 is about 25 "to 75 percent by weight of the composite particles" . 19. The method according to claim 15, characterized in that fibers from the Paser dispersion first is deposited as an initial, thinned, fibrous base paper material "before the heat seal is able to do so Particles are deposited to form a two-layer paper material for infusion purposes. 2098K / 1492 Hs Blank page